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Wu P, Xu L, Wang Q, Ma X, Wang X, Wang H, He S, Ru H, Zhao Y, Xiao Y, Zhang J, Wang X, An S, Hacker M, Li X, Zhang X, Wang Y, Yang M, Wu Z, Li S. Left Ventricular Remodelling Associated with the Transient Elevated [ 68Ga]Ga-Pentixafor Activity in the Remote Myocardium Following Acute Myocardial Infarction. Mol Imaging Biol 2024; 26:693-703. [PMID: 38641708 DOI: 10.1007/s11307-024-01912-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 02/17/2024] [Accepted: 03/14/2024] [Indexed: 04/21/2024]
Abstract
BACKGROUND Previous studies have initially reported accompanying elevated 2-deoxy-2[18F]fluoro-D-glucose ([18F]F-FDG) inflammatory activity in the remote area and its prognostic value after acute myocardial infarction (AMI). Non-invasive characterization of the accompanying inflammation in the remote myocardium may be of potency in guiding future targeted theranostics. [68Ga]Ga-Pentixafor targeting chemokine receptor 4 (CXCR4) on the surface of inflammatory cells is currently one of the promising inflammatory imaging agents. In this study, we sought to focus on the longitudinal evolution of [68Ga]Ga-Pentixafor activities in the remote myocardium following AMI and its association with cardiac function. METHODS Twelve AMI rats and six Sham rats serially underwent [68Ga]Ga-Pentixafor imaging at pre-operation, and 5, 7, 14 days post-operation. Maximum and mean standard uptake value (SUV) and target-to-background ratio (TBR) were assessed to indicate the uptake intensity. Gated [18F]F-FDG imaging and immunofluorescent staining were performed to obtain cardiac function and responses of pro-inflammatory and reparative macrophages, respectively. RESULTS The uptake of [68Ga]Ga-Pentixafor in the infarcted myocardium peaked at day 5 (all P = 0.003), retained at day 7 (all P = 0.011), and recovered at day 14 after AMI (P > 0.05), paralleling with the rise-fall pro-inflammatory M1 macrophages (P < 0.05). Correlated with the peak activity in the infarct territory, [68Ga]Ga-Pentixafor uptake in the remote myocardium on day 5 early after AMI significantly increased (AMI vs. Sham: SUVmean, SUVmax, and TBRmean: all P < 0.05), and strongly correlated with contemporaneous EDV and/or ESV (SUVmean and TBRmean: both P < 0.05). The transitory remote activity recovered as of day 7 post-AMI (AMI vs. Sham: P > 0.05). CONCLUSIONS Corresponding with the peaked [68Ga]Ga-Pentixafor activity in the infarcted myocardium, the activity in the remote region elevated accordingly and led to contemporaneous left ventricular remodelling early after AMI. Further studies are warranted to clarify its clinical application potential.
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Affiliation(s)
- Ping Wu
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Shanxi Medical University, Taiyuan, China
| | - Li Xu
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Shanxi Medical University, Taiyuan, China
| | - Qi Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Shanxi Medical University, Taiyuan, China
| | - Xiaofang Ma
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China
| | - Xinzhu Wang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Shanxi Medical University, Taiyuan, China
| | - Hongliang Wang
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Shanxi Medical University, Taiyuan, China
| | - Sheng He
- Department of Radiology, First Hospital of Shanxi Medical University, Taiyuan, China
| | - Huibin Ru
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Shanxi Medical University, Taiyuan, China
| | - Yuting Zhao
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China
| | - Yuxin Xiao
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China
| | - Jingying Zhang
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China
| | - Xinchao Wang
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Shanxi Medical University, Taiyuan, China
| | - Shaohui An
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Shanxi Medical University, Taiyuan, China
- Shanghai United Imaging Healthcare Co., Ltd., Shanghai, China
| | - Marcus Hacker
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Xiang Li
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
| | - Xiaoli Zhang
- Laboratory for Molecular Imaging, Department of Nuclear Medicine, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Yuetao Wang
- Department of Nuclear Medicine, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu, China
| | - Minfu Yang
- Department of Nuclear Medicine, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Zhifang Wu
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Shanxi Medical University, Taiyuan, China
| | - Sijin Li
- Department of Nuclear Medicine, First Hospital of Shanxi Medical University, No. 85 Jiefang South Road, Taiyuan, 030001, Shanxi, China.
- Collaborative Innovation Center for Molecular Imaging of Precision Medicine, Shanxi Medical University, Taiyuan, China.
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Zatcepin A, Kopczak A, Holzgreve A, Hein S, Schindler A, Duering M, Kaiser L, Lindner S, Schidlowski M, Bartenstein P, Albert N, Brendel M, Ziegler SI. Machine learning-based approach reveals essential features for simplified TSPO PET quantification in ischemic stroke patients. Z Med Phys 2024; 34:218-230. [PMID: 36682921 PMCID: PMC11156782 DOI: 10.1016/j.zemedi.2022.11.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 11/18/2022] [Accepted: 11/19/2022] [Indexed: 01/21/2023]
Abstract
INTRODUCTION Neuroinflammation evaluation after acute ischemic stroke is a promising option for selecting an appropriate post-stroke treatment strategy. To assess neuroinflammation in vivo, translocator protein PET (TSPO PET) can be used. However, the gold standard TSPO PET quantification method includes a 90 min scan and continuous arterial blood sampling, which is challenging to perform on a routine basis. In this work, we determine what information is required for a simplified quantification approach using a machine learning algorithm. MATERIALS AND METHODS We analyzed data from 18 patients with ischemic stroke who received 0-90 min [18F]GE-180 PET as well as T1-weigted (T1w), FLAIR, and arterial spin labeling (ASL) MRI scans. During PET scans, five manual venous blood samples at 5, 15, 30, 60, and 85 min post injection (p.i.) were drawn, and plasma activity concentration was measured. Total distribution volume (VT) was calculated using Logan plot with the full dynamic PET and an image-derived input function (IDIF) from the carotid arteries. IDIF was scaled by a calibration factor derived from all the measured plasma activity concentrations. The calculated VT values were used for training a random forest regressor. As input features for the model, we used three late PET frames (60-70, 70-80, and 80-90 min p.i.), the ASL image reflecting perfusion, the voxel coordinates, the lesion mask, and the five plasma activity concentrations. The algorithm was validated with the leave-one-out approach. To estimate the impact of the individual features on the algorithm's performance, we used Shapley Additive Explanations (SHAP). Having determined that the three late PET frames and the plasma activity concentrations were the most important features, we tested a simplified quantification approach consisting of dividing a late PET frame by a plasma activity concentration. All the combinations of frames/samples were compared by means of concordance correlation coefficient and Bland-Altman plots. RESULTS When using all the input features, the algorithm predicted VT values with high accuracy (87.8 ± 8.3%) for both lesion and non-lesion voxels. The SHAP values demonstrated high impact of the late PET frames (60-70, 70-80, and 80-90 min p.i.) and plasma activity concentrations on the VT prediction, while the influence of the ASL-derived perfusion, voxel coordinates, and the lesion mask was low. Among all the combinations of the late PET frames and plasma activity concentrations, the 70-80 min p.i. frame divided by the 30 min p.i. plasma sample produced the closest VT estimate in the ischemic lesion. CONCLUSION Reliable TSPO PET quantification is achievable by using a single late PET frame divided by a late blood sample activity concentration.
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Affiliation(s)
- Artem Zatcepin
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.
| | - Anna Kopczak
- Institute for Stroke and Dementia Research (ISD), University Hospital, LMU Munich, Munich, Germany
| | - Adrien Holzgreve
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Sandra Hein
- Institute for Stroke and Dementia Research (ISD), University Hospital, LMU Munich, Munich, Germany
| | - Andreas Schindler
- Department of Neuroradiology, University Hospital, LMU Munich, Munich, Germany
| | - Marco Duering
- Institute for Stroke and Dementia Research (ISD), University Hospital, LMU Munich, Munich, Germany; Medical Image Analysis Center (MIAC) & Department of Biomedical Engineering, University of Basel, Basel, Switzerland
| | - Lena Kaiser
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Simon Lindner
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Martin Schidlowski
- Department of Epileptology, University Hospital Bonn, Bonn, Germany; German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Peter Bartenstein
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Nathalie Albert
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - Matthias Brendel
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Munich, Germany; Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Sibylle I Ziegler
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
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Lee K, Niku S, Koo SJ, Belezzuoli E, Guma M. Molecular imaging for evaluation of synovitis associated with osteoarthritis: a narrative review. Arthritis Res Ther 2024; 26:25. [PMID: 38229205 PMCID: PMC10790518 DOI: 10.1186/s13075-023-03258-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 12/28/2023] [Indexed: 01/18/2024] Open
Abstract
Recent evidence highlights the role of low-grade synovial inflammation in the progression of osteoarthritis (OA). Inflamed synovium of OA joints detected by imaging modalities are associated with subsequent progression of OA. In this sense, detecting and quantifying synovitis of OA by imaging modalities may be valuable in predicting OA progressors as well as in improving our understanding of OA progression. Of the several imaging modalities, molecular imaging such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) has an advantage of visualizing the cellular or subcellular events of the tissues. Depending on the radiotracers used, molecular imaging method can potentially detect and visualize various aspects of synovial inflammation. This narrative review summarizes the recent progresses of imaging modalities in assessing inflammation and OA synovitis and focuses on novel radiotracers. Recent studies about imaging modalities including ultrasonography (US), magnetic resonance imaging (MRI), and molecular imaging that were used to detect and quantify inflammation and OA synovitis are summarized. Novel radiotracers specifically targeting the components of inflammation have been developed. These tracers may show promise in detecting inflamed synovium of OA and help in expanding our understanding of OA progression.
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Affiliation(s)
- Kwanghoon Lee
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
- Department of Medicine, Dongguk University Ilsan Hospital, Goyang, Korea
| | - Soheil Niku
- Nuclear Medicine Service, Jennifer Moreno VA San Diego Healthcare System, San Diego, CA, USA
| | - Sonya J Koo
- Department of Radiology, West Los Angeles VA Medical Center, Los Angeles, CA, USA
| | - Ernest Belezzuoli
- Nuclear Medicine Service, Jennifer Moreno VA San Diego Healthcare System, San Diego, CA, USA
- Department of Radiology, University of California San Diego, La Jolla, CA, USA
| | - Monica Guma
- Department of Medicine, University of California San Diego, La Jolla, CA, USA.
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Cools R, Kerkhofs K, Leitao RCF, Bormans G. Preclinical Evaluation of Novel PET Probes for Dementia. Semin Nucl Med 2023; 53:599-629. [PMID: 37149435 DOI: 10.1053/j.semnuclmed.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 03/24/2023] [Indexed: 05/08/2023]
Abstract
The development of novel PET imaging agents that selectively bind specific dementia-related targets can contribute significantly to accurate, differential and early diagnosis of dementia causing diseases and support the development of therapeutic agents. Consequently, in recent years there has been a growing body of literature describing the development and evaluation of potential new promising PET tracers for dementia. This review article provides a comprehensive overview of novel dementia PET probes under development, classified by their target, and pinpoints their preclinical evaluation pathway, typically involving in silico, in vitro and ex/in vivo evaluation. Specific target-associated challenges and pitfalls, requiring extensive and well-designed preclinical experimental evaluation assays to enable successful clinical translation and avoid shortcomings observed for previously developed 'well-established' dementia PET tracers are highlighted in this review.
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Affiliation(s)
- Romy Cools
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Kobe Kerkhofs
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium; NURA, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Renan C F Leitao
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Guy Bormans
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
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Chaney AM, Cropper HC, Jain P, Wilson E, Simonetta F, Johnson EM, Alam IS, Patterson ITJ, Swarovski M, Stevens MY, Wang Q, Azevedo C, Nagy SC, Ramos Benitez J, Deal EM, Vogel H, Andreasson KI, James ML. PET imaging of TREM1 identifies CNS-infiltrating myeloid cells in a mouse model of multiple sclerosis. Sci Transl Med 2023; 15:eabm6267. [PMID: 37379371 DOI: 10.1126/scitranslmed.abm6267] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Accepted: 06/02/2023] [Indexed: 06/30/2023]
Abstract
Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system (CNS) that causes substantial morbidity and diminished quality of life. Evidence highlights the central role of myeloid lineage cells in the initiation and progression of MS. However, existing imaging strategies for detecting myeloid cells in the CNS cannot distinguish between beneficial and harmful immune responses. Thus, imaging strategies that specifically identify myeloid cells and their activation states are critical for MS disease staging and monitoring of therapeutic responses. We hypothesized that positron emission tomography (PET) imaging of triggering receptor expressed on myeloid cells 1 (TREM1) could be used to monitor deleterious innate immune responses and disease progression in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. We first validated TREM1 as a specific marker of proinflammatory, CNS-infiltrating, peripheral myeloid cells in mice with EAE. We show that the 64Cu-radiolabeled TREM1 antibody-based PET tracer monitored active disease with 14- to 17-fold higher sensitivity than translocator protein 18 kDa (TSPO)-PET imaging, the established approach for detecting neuroinflammation in vivo. We illustrate the therapeutic potential of attenuating TREM1 signaling both genetically and pharmacologically in the EAE mice and show that TREM1-PET imaging detected responses to an FDA-approved MS therapy with siponimod (BAF312) in these animals. Last, we observed TREM1+ cells in clinical brain biopsy samples from two treatment-naïve patients with MS but not in healthy control brain tissue. Thus, TREM1-PET imaging has potential for aiding in the diagnosis of MS and monitoring of therapeutic responses to drug treatment.
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Affiliation(s)
- Aisling M Chaney
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
- Department of Radiology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Haley C Cropper
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Poorva Jain
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Edward Wilson
- Department of Neurology and Neurological Science, Stanford University, Stanford, CA 94305, USA
| | - Federico Simonetta
- Division of Hematology, Department of Oncology, Geneva University Hospitals, Geneva 1205, Switzerland
- Translational Research Centre in Onco-Haematology, Faculty of Medicine, University of Geneva, Geneva 1205, Switzerland
| | - Emily M Johnson
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Israt S Alam
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Ian T J Patterson
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Michelle Swarovski
- Department of Neurology and Neurological Science, Stanford University, Stanford, CA 94305, USA
| | - Marc Y Stevens
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Qian Wang
- Department of Neurology and Neurological Science, Stanford University, Stanford, CA 94305, USA
| | - Carmen Azevedo
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Sydney C Nagy
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Javier Ramos Benitez
- Department of Neurology and Neurological Science, Stanford University, Stanford, CA 94305, USA
| | - Emily M Deal
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
| | - Hannes Vogel
- Department of Pathology, Stanford University, Stanford, CA 94305, USA
| | - Katrin I Andreasson
- Department of Neurology and Neurological Science, Stanford University, Stanford, CA 94305, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Michelle L James
- Department of Radiology, Stanford University, Stanford, CA 94305, USA
- Department of Neurology and Neurological Science, Stanford University, Stanford, CA 94305, USA
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Leńska-Mieciek M, Madetko-Alster N, Alster P, Królicki L, Fiszer U, Koziorowski D. Inflammation in multiple system atrophy. Front Immunol 2023; 14:1214677. [PMID: 37426656 PMCID: PMC10327640 DOI: 10.3389/fimmu.2023.1214677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/06/2023] [Indexed: 07/11/2023] Open
Abstract
Misfolding protein aggregation inside or outside cells is the major pathological hallmark of several neurodegenerative diseases. Among proteinopathies are neurodegenerative diseases with atypical Parkinsonism and an accumulation of insoluble fibrillary alpha-synuclein (synucleinopathies) or hyperphosphorylated tau protein fragments (tauopathies). As there are no therapies available to slow or halt the progression of these disea ses, targeting the inflammatory process is a promising approach. The inflammatory biomarkers could also help in the differential diagnosis of Parkinsonian syndromes. Here, we review inflammation's role in multiple systems atrophy pathogenesis, diagnosis, and treatment.
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Affiliation(s)
- Marta Leńska-Mieciek
- Department of Neurology and Epileptology, Centre of Postgraduate Medical Education, Warsaw, Poland
| | | | - Piotr Alster
- Department of Neurology, Medical University of Warsaw, Warsaw, Poland
| | - Leszek Królicki
- Department of Nuclear Medicine, Medical University of Warsaw, Warsaw, Poland
| | - Urszula Fiszer
- Department of Neurology and Epileptology, Centre of Postgraduate Medical Education, Warsaw, Poland
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Wang Y, Tian A, Zhang F, Yu J, Ling J. Inflammatory Immune Process and Depression-like Behavior in Hypothyroid Rats: A [ 18F] DPA-714 Micro Positron Emission Tomography Study. Pharmaceuticals (Basel) 2023; 16:279. [PMID: 37259424 PMCID: PMC9964991 DOI: 10.3390/ph16020279] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 02/04/2023] [Accepted: 02/08/2023] [Indexed: 10/24/2023] Open
Abstract
Hypothyroidism is closely related to mental disorders, mainly depression, through an as-yet-unknown mechanism. The cerebral inflammatory immune process has been implied to play a pivotal role in the onset of affective symptoms in several conditions. In order to gain insight into the mechanism underlying the depressive behaviors in hypothyroid rats, brain microglial activation was evaluated using micro positron emission tomography imaging with a translocator protein (TSPO) radioligand. Hypothyroidism was induced in adult male Wistar rats by administration of 0.05% propylthiouracil in drinking water for five weeks. Open field, forced swimming and tail suspension tests were employed to evaluate the depressive behavior in hypothyroid rats, and the relationship between the behavioral changes and brain microglial activation was evaluated using [18F] DPA-714 micro positron emission tomography imaging. The open field test revealed significantly reduced first-minute activity and rearing behavior in the hypothyroid group, as well as significantly increased immobility in the forced swimming test and the tail suspension test. Hypothyroidism induced significantly increased microglial activation in the hippocampus. The radioligand uptake in the hippocampus correlated negatively with first-minute activity in the open field test (p < 0.05), and the radioligand uptake in the hippocampus correlated positively with changes in the immobility time in the forced swimming test and the tail suspension test (p < 0.05). Immunohistochemistry also confirmed the activation of microglia and inflammatory bodies in hypothyroid rats. The results indicate that hypothyroidism can induce depressive behavior in adult Wistar rats, microglial activation in the hippocampus plays an important role in the depressive behavior in hypothyroid rats and the inflammatory immune mechanism may underlie the behavioral abnormalities in thyroid dysfunction. Furthermore, the findings in the present study suggest there might be a common mechanism underlying depressive behavior in adult-onset hypothyroidism and depression.
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Affiliation(s)
- Yizhen Wang
- Second Affiliated Hospital, Dalian Medical University, Dalian 116027, China
| | - Aijuan Tian
- Second Affiliated Hospital, Dalian Medical University, Dalian 116027, China
| | - Fang Zhang
- Second Affiliated Hospital, Dalian Medical University, Dalian 116027, China
- Nuclear Medicine Division, Shengli Oilfield Central Hospital, Dongying 257000, China
| | - Jing Yu
- Second Affiliated Hospital, Dalian Medical University, Dalian 116027, China
| | - Jianer Ling
- Second Affiliated Hospital, Dalian Medical University, Dalian 116027, China
- Hwa Mei Hospital, University of Chinese Academy of Sciences, Ningbo 315010, China
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8
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Yang Z, Banks SJ, Ritter AR, Cummings JL, Sreenivasan K, Kinney JW, Caldwell JK, Wong CG, Miller JB, Cordes D. Microglial Imaging in Alzheimer's Disease and Its Relationship to Brain Amyloid: A Human 18F-GE180 PET Study. J Alzheimers Dis 2023; 96:1505-1514. [PMID: 37980664 PMCID: PMC10894577 DOI: 10.3233/jad-230631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2023] [Indexed: 11/21/2023]
Abstract
BACKGROUND Emerging evidence suggests a potential causal role of neuroinflammation in Alzheimer's disease (AD). Using positron emission tomography (PET) to image overexpressed 18 kDA translocator protein (TSPO) by activated microglia has gained increasing interest. The uptake of 18F-GE180 TSPO PET was observed to co-localize with inflammatory markers and have a two-stage association with amyloid PET in mice. Very few studies evaluated the diagnostic power of 18F-GE180 PET in AD population and its interpretation in human remains controversial about whether it is a marker of microglial activation or merely reflects disrupted blood-brain barrier integrity in humans. OBJECTIVE The goal of this study was to study human GE180 from the perspective of the previous animal observations. METHODS With data from twenty-four participants having 18F-GE180 and 18F-AV45 PET scans, we evaluated the group differences of 18F-GE180 uptake between participants with and without cognitive impairment. An association analysis of 18F-GE180 and 18F-AV45 was then conducted to test if the relationship in humans is consistent with the two-stage association in AD mouse model. RESULTS Elevated 18F-GE180 was observed in participants with cognitive impairment compared to those with normal cognition. No regions showed reduced 18F-GE180 uptake. Consistent with mouse model, a two-stage association between 18F-GE180 and 18F-AV45 was observed. CONCLUSIONS 18F-GE180 PET imaging showed promising utility in detecting pathological alterations in a symptomatic AD population. Consistent two-stage association between 18F-GE180 and amyloid PET in human and mouse suggested that 18F-GE180 uptake in human might be considerably influenced by microglial activation.
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Affiliation(s)
- Zhengshi Yang
- Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA
- Department of Brain Health, University of Nevada Las Vegas, Las Vegas, NV, USA
| | | | - Aaron R. Ritter
- Hoag’s Pickup Family Neurosciences Institute, Newport Beach, CA, USA
| | - Jeffrey L. Cummings
- Department of Brain Health, University of Nevada Las Vegas, Las Vegas, NV, USA
- Chambers-Grundy Center for Transformative Neuroscience, Pam Quirk Brain Health and Biomarker Laboratory, Department of Brain Health, School of Integrated Health Sciences, University of Nevada Las Vegas (UNLV), Las Vegas, NV, USA
| | - Karthik Sreenivasan
- Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA
- Department of Brain Health, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Jefferson W. Kinney
- Department of Brain Health, University of Nevada Las Vegas, Las Vegas, NV, USA
- Chambers-Grundy Center for Transformative Neuroscience, Pam Quirk Brain Health and Biomarker Laboratory, Department of Brain Health, School of Integrated Health Sciences, University of Nevada Las Vegas (UNLV), Las Vegas, NV, USA
| | | | - Christina G. Wong
- Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA
| | - Justin B. Miller
- Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA
| | - Dietmar Cordes
- Cleveland Clinic Lou Ruvo Center for Brain Health, Las Vegas, NV, USA
- Department of Brain Health, University of Nevada Las Vegas, Las Vegas, NV, USA
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO, USA
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18F-Radiolabeled Translocator Protein (TSPO) PET Tracers: Recent Development of TSPO Radioligands and Their Application to PET Study. Pharmaceutics 2022; 14:pharmaceutics14112545. [PMID: 36432736 PMCID: PMC9697781 DOI: 10.3390/pharmaceutics14112545] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
Abstract
Translocator protein 18 kDa (TSPO) is a transmembrane protein in the mitochondrial membrane, which has been identified as a peripheral benzodiazepine receptor. TSPO is generally present at high concentrations in steroid-producing cells and plays an important role in steroid synthesis, apoptosis, and cell proliferation. In the central nervous system, TSPO expression is relatively modest under normal physiological circumstances. However, some pathological disorders can lead to changes in TSPO expression. Overexpression of TSPO is associated with several diseases, such as neurodegenerative diseases, neuroinflammation, brain injury, and cancers. TSPO has therefore become an effective biomarker of related diseases. Positron emission tomography (PET), a non-invasive molecular imaging technique used for the clinical diagnosis of numerous diseases, can detect diseases related to TSPO expression. Several radiolabeled TSPO ligands have been developed for PET. In this review, we describe recent advances in the development of TSPO ligands, and 18F-radiolabeled TSPO in particular, as PET tracers. This review covers pharmacokinetic studies, preclinical and clinical trials of 18F-labeled TSPO PET ligands, and the synthesis of TSPO ligands.
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10
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Ni R, Müller Herde A, Haider A, Keller C, Louloudis G, Vaas M, Schibli R, Ametamey SM, Klohs J, Mu L. In vivo Imaging of Cannabinoid Type 2 Receptors: Functional and Structural Alterations in Mouse Model of Cerebral Ischemia by PET and MRI. Mol Imaging Biol 2022; 24:700-709. [PMID: 34642898 PMCID: PMC9581861 DOI: 10.1007/s11307-021-01655-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 02/07/2023]
Abstract
PURPOSE Stroke is one of the most prevalent vascular diseases. Non-invasive molecular imaging methods have the potential to provide critical insights into the temporal dynamics and follow alterations of receptor expression and metabolism in ischemic stroke. The aim of this study was to assess the cannabinoid type 2 receptor (CB2R) levels in transient middle cerebral artery occlusion (tMCAO) mouse models at subacute stage using positron emission tomography (PET) with our novel tracer [18F]RoSMA-18-d6 and structural imaging by magnetic resonance imaging (MRI). PROCEDURES Our recently developed CB2R PET tracer [18F]RoSMA-18-d6 was used for imaging neuroinflammation at 24 h after reperfusion in tMCAO mice. The RNA expression levels of CB2R and other inflammatory markers were analyzed by quantitative real-time polymerase chain reaction using brain tissues from tMCAO (1 h occlusion) and sham-operated mice. [18F]fluorodeoxyglucose (FDG) was included for evaluation of the cerebral metabolic rate of glucose (CMRglc). In addition, diffusion-weighted imaging and T2-weighted imaging were performed for anatomical reference and delineating the lesion in tMCAO mice. RESULTS mRNA expressions of inflammatory markers TNF-α, Iba1, MMP9 and GFAP, CNR2 were increased to 1.3-2.5 fold at 24 h after reperfusion in the ipsilateral compared to contralateral hemisphere of tMCAO mice, while mRNA expression of the neuronal marker MAP-2 was markedly reduced to ca. 50 %. Reduced [18F]FDG uptake was observed in the ischemic striatum of tMCAO mouse brain at 24 h after reperfusion. Although higher activity of [18F]RoSMA-18-d6 in ex vivo biodistribution studies and higher standard uptake value ratio (SUVR) were detected in the ischemic ipsilateral compared to contralateral striatum in tMCAO mice, the in vivo specificity of [18F]RoSMA-18-d6 was confirmed only in the CB2R-rich spleen. CONCLUSIONS This study revealed an increased [18F]RoSMA-18-d6 measure of CB2R and a reduced [18F]FDG measure of CMRglc in the ischemic striatum of tMCAO mice at subacute stage. [18F]RoSMA-18-d6 might be a promising PET tracer for detecting CB2R alterations in animal models of neuroinflammation without neuronal loss.
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Affiliation(s)
- Ruiqing Ni
- Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland
- Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
| | - Adrienne Müller Herde
- Department of Chemistry and Applied Biosciences, ETH Zurich, HCI H427 Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
| | - Ahmed Haider
- Department of Chemistry and Applied Biosciences, ETH Zurich, HCI H427 Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
| | - Claudia Keller
- Department of Chemistry and Applied Biosciences, ETH Zurich, HCI H427 Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
| | - Georgios Louloudis
- Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland
| | - Markus Vaas
- Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland
| | - Roger Schibli
- Department of Chemistry and Applied Biosciences, ETH Zurich, HCI H427 Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
| | - Simon M Ametamey
- Department of Chemistry and Applied Biosciences, ETH Zurich, HCI H427 Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland
| | - Jan Klohs
- Institute for Biomedical Engineering, University of Zurich & ETH Zurich, Zurich, Switzerland
| | - Linjing Mu
- Department of Chemistry and Applied Biosciences, ETH Zurich, HCI H427 Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland.
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.
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11
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Viviano M, Barresi E, Siméon FG, Costa B, Taliani S, Da Settimo F, Pike VW, Castellano S. Essential Principles and Recent Progress in the Development of TSPO PET Ligands for Neuroinflammation Imaging. Curr Med Chem 2022; 29:4862-4890. [PMID: 35352645 PMCID: PMC10080361 DOI: 10.2174/0929867329666220329204054] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 12/21/2021] [Accepted: 01/25/2022] [Indexed: 11/22/2022]
Abstract
The translocator protein 18kDa (TSPO) is expressed in the outer mitochondrial membrane and is implicated in several functions, including cholesterol transport and steroidogenesis. Under normal physiological conditions, TSPO is present in very low concentrations in the human brain but is markedly upregulated in response to brain injury and inflammation. This upregulation is strongly associated with activated microglia. Therefore, TSPO is particularly suited for assessing active gliosis associated with brain lesions following injury or disease. For over three decades, TSPO has been studied as a biomarker. Numerous radioligands for positron emission tomography (PET) that target TSPO have been developed for imaging inflammatory progression in the brain. Although [11C]PK11195, the prototypical first-generation PET radioligand, is still widely used for in vivo studies, mainly now as its single more potent R-enantiomer, it has severe limitations, including low sensitivity and poor amenability to quantification. Second-generation radioligands are characterized by higher TSPO specific signals but suffer from other drawbacks, such as sensitivity to the TSPO single nucleotide polymorphism (SNP) rs6971. Therefore, their applications in human studies have the burden of needing to genotype subjects. Consequently, recent efforts are focused on developing improved radioligands that combine the optimal features of the second generation with the ability to overcome the differences in binding affinities across the population. This review presents essential principles in the design and development of TSPO PET ligands and discusses prominent examples among the main chemotypes.
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Affiliation(s)
- Monica Viviano
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy
| | | | - Fabrice G. Siméon
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Barbara Costa
- Department of Pharmacy, University of Pisa, 56126, Pisa, Italy
| | - Sabrina Taliani
- Department of Pharmacy, University of Pisa, 56126, Pisa, Italy
| | | | - Victor W. Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sabrina Castellano
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy
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12
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Singh P, Adhikari A, Singh D, Gond C, Tiwari AK. The 18-kDa Translocator Protein PET Tracers as a Diagnostic Marker for Neuroinflammation: Development and Current Standing. ACS OMEGA 2022; 7:14412-14429. [PMID: 35557664 PMCID: PMC9089361 DOI: 10.1021/acsomega.2c00588] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/05/2022] [Indexed: 05/13/2023]
Abstract
Translocator protein (TSPO, 18 kDa) is an evolutionary, well-preserved, and tryptophan-rich 169-amino-acid protein which localizes on the contact sites between the outer and inner mitochondrial membranes of steroid-synthesizing cells. This mitochondrial protein is implicated in an extensive range of cellular activities, including steroid synthesis, cholesterol transport, apoptosis, mitochondrial respiration, and cell proliferation. The upregulation of TSPO is well documented in diverse disease conditions including neuroinflammation, cancer, brain injury, and inflammation in peripheral organs. On the basis of these outcomes, TSPO has been assumed to be a fascinating subcellular target for early stage imaging of the diseased state and for therapeutic purposes. The main outline of this Review is to give an update on dealing with the advances made in TSPO PET tracers for neuroinflammation, synchronously emphasizing the approaches applied for the design and advancement of new tracers with reference to their structure-activity relationship (SAR).
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Affiliation(s)
- Priya Singh
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
| | - Anupriya Adhikari
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
| | - Deepika Singh
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
| | - Chandraprakash Gond
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
| | - Anjani Kumar Tiwari
- Department
of Chemistry, Babasaheb Bhimrao Ambedkar
University (A Central University), Lucknow, 226025, Uttar Pradesh, India
- Address:
Department of Chemistry,
Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh. Tel.: +91-7503381343. Fax: +91-522-2440821. E-mail:
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13
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Crișan G, Moldovean-Cioroianu NS, Timaru DG, Andrieș G, Căinap C, Chiș V. Radiopharmaceuticals for PET and SPECT Imaging: A Literature Review over the Last Decade. Int J Mol Sci 2022; 23:ijms23095023. [PMID: 35563414 PMCID: PMC9103893 DOI: 10.3390/ijms23095023] [Citation(s) in RCA: 61] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 04/23/2022] [Accepted: 04/28/2022] [Indexed: 02/04/2023] Open
Abstract
Positron emission tomography (PET) uses radioactive tracers and enables the functional imaging of several metabolic processes, blood flow measurements, regional chemical composition, and/or chemical absorption. Depending on the targeted processes within the living organism, different tracers are used for various medical conditions, such as cancer, particular brain pathologies, cardiac events, and bone lesions, where the most commonly used tracers are radiolabeled with 18F (e.g., [18F]-FDG and NA [18F]). Oxygen-15 isotope is mostly involved in blood flow measurements, whereas a wide array of 11C-based compounds have also been developed for neuronal disorders according to the affected neuroreceptors, prostate cancer, and lung carcinomas. In contrast, the single-photon emission computed tomography (SPECT) technique uses gamma-emitting radioisotopes and can be used to diagnose strokes, seizures, bone illnesses, and infections by gauging the blood flow and radio distribution within tissues and organs. The radioisotopes typically used in SPECT imaging are iodine-123, technetium-99m, xenon-133, thallium-201, and indium-111. This systematic review article aims to clarify and disseminate the available scientific literature focused on PET/SPECT radiotracers and to provide an overview of the conducted research within the past decade, with an additional focus on the novel radiopharmaceuticals developed for medical imaging.
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Affiliation(s)
- George Crișan
- Faculty of Physics, Babeş-Bolyai University, Str. M. Kogălniceanu 1, 400084 Cluj-Napoca, Romania; (G.C.); (N.S.M.-C.); (D.-G.T.)
- Department of Nuclear Medicine, County Clinical Hospital, Clinicilor 3-5, 400006 Cluj-Napoca, Romania;
| | | | - Diana-Gabriela Timaru
- Faculty of Physics, Babeş-Bolyai University, Str. M. Kogălniceanu 1, 400084 Cluj-Napoca, Romania; (G.C.); (N.S.M.-C.); (D.-G.T.)
| | - Gabriel Andrieș
- Department of Nuclear Medicine, County Clinical Hospital, Clinicilor 3-5, 400006 Cluj-Napoca, Romania;
| | - Călin Căinap
- The Oncology Institute “Prof. Dr. Ion Chiricuţă”, Republicii 34-36, 400015 Cluj-Napoca, Romania;
| | - Vasile Chiș
- Faculty of Physics, Babeş-Bolyai University, Str. M. Kogălniceanu 1, 400084 Cluj-Napoca, Romania; (G.C.); (N.S.M.-C.); (D.-G.T.)
- Institute for Research, Development and Innovation in Applied Natural Sciences, Babeș-Bolyai University, Str. Fântânele 30, 400327 Cluj-Napoca, Romania
- Correspondence:
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14
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Zatcepin A, Heindl S, Schillinger U, Kaiser L, Lindner S, Bartenstein P, Kopczak A, Liesz A, Brendel M, Ziegler SI. Reduced Acquisition Time [18F]GE-180 PET Scanning Protocol Replaces Gold-Standard Dynamic Acquisition in a Mouse Ischemic Stroke Model. Front Med (Lausanne) 2022; 9:830020. [PMID: 35223925 PMCID: PMC8866959 DOI: 10.3389/fmed.2022.830020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 01/17/2022] [Indexed: 02/04/2023] Open
Abstract
AimUnderstanding neuroinflammation after acute ischemic stroke is a crucial step on the way to an individualized post-stroke treatment. Microglia activation, an essential part of neuroinflammation, can be assessed using [18F]GE-180 18 kDa translocator protein positron emission tomography (TSPO-PET). However, the commonly used 60–90 min post-injection (p.i.) time window was not yet proven to be suitable for post-stroke neuroinflammation assessment. In this study, we compare semi-quantitative estimates derived from late time frames to quantitative estimates calculated using a full 0–90 min dynamic scan in a mouse photothrombotic stroke (PT) model.Materials and MethodsSix mice after PT and six sham mice were included in the study. For a half of the mice, we acquired four serial 0–90 min scans per mouse (analysis cohort) and calculated standardized uptake value ratios (SUVRs; cerebellar reference) for the PT volume of interest (VOI) in five late 10 min time frames as well as distribution volume ratios (DVRs) for the same VOI. We compared late static 10 min SUVRs and the 60–90 min time frame of the analysis cohort to the corresponding DVRs by linear fitting. The other half of the animals received a static 60–90 min scan and was used as a validation cohort. We extrapolated DVRs by using the static 60–90 min p.i. time window, which were compared to the DVRs of the analysis cohort.ResultsWe found high linear correlations between SUVRs and DVRs in the analysis cohort for all studied 10 min time frames, while the fits of the 60–70, 70–80, and 80–90 min p.i. time frames were the ones closest to the line of identity. For the 60–90 min time window, we observed an excellent linear correlation between SUVR and DVR regardless of the phenotype (PT vs. sham). The extrapolated DVRs of the validation cohort were not significantly different from the DVRs of the analysis group.ConclusionSimplified quantification by a reference tissue ratio of the late 60–90 min p.i. [18F]GE-180 PET image can replace full quantification of a dynamic scan for assessment of microglial activation in the mouse PT model.
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Affiliation(s)
- Artem Zatcepin
- Department of Nuclear Medicine, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Munich, Germany
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
- *Correspondence: Artem Zatcepin
| | - Steffanie Heindl
- Institute for Stroke and Dementia Research, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Institute for Stroke and Dementia Research, Munich, Germany
| | - Ulrike Schillinger
- Institute for Stroke and Dementia Research, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Institute for Stroke and Dementia Research, Munich, Germany
| | - Lena Kaiser
- Department of Nuclear Medicine, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Munich, Germany
| | - Simon Lindner
- Department of Nuclear Medicine, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Munich, Germany
| | - Peter Bartenstein
- Department of Nuclear Medicine, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Anna Kopczak
- Institute for Stroke and Dementia Research, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Institute for Stroke and Dementia Research, Munich, Germany
| | - Arthur Liesz
- Institute for Stroke and Dementia Research, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Institute for Stroke and Dementia Research, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Matthias Brendel
- Department of Nuclear Medicine, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Munich, Germany
- German Center for Neurodegenerative Diseases (DZNE) Munich, Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
| | - Sibylle I. Ziegler
- Department of Nuclear Medicine, University Hospital of Ludwig-Maximilians-Universität (LMU) Munich, Munich, Germany
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15
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Harada R, Furumoto S, Kudo Y, Yanai K, Villemagne VL, Okamura N. Imaging of Reactive Astrogliosis by Positron Emission Tomography. Front Neurosci 2022; 16:807435. [PMID: 35210989 PMCID: PMC8862631 DOI: 10.3389/fnins.2022.807435] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/14/2022] [Indexed: 11/13/2022] Open
Abstract
Many neurodegenerative diseases are neuropathologically characterized by neuronal loss, gliosis, and the deposition of misfolded proteins such as β-amyloid (Aβ) plaques and tau tangles in Alzheimer’s disease (AD). In postmortem AD brains, reactive astrocytes and activated microglia are observed surrounding Aβ plaques and tau tangles. These activated glial cells secrete pro-inflammatory cytokines and reactive oxygen species, which may contribute to neurodegeneration. Therefore, in vivo imaging of glial response by positron emission tomography (PET) combined with Aβ and tau PET would provide new insights to better understand the disease process, as well as aid in the differential diagnosis, and monitoring glial response disease-specific therapeutics. There are two promising targets proposed for imaging reactive astrogliosis: monoamine oxidase-B (MAO-B) and imidazoline2 binding site (I2BS), which are predominantly expressed in the mitochondrial membranes of astrocytes and are upregulated in various neurodegenerative conditions. PET tracers targeting these two MAO-B and I2BS have been evaluated in humans. [18F]THK-5351, which was originally designed to target tau aggregates in AD, showed high affinity for MAO-B and clearly visualized reactive astrocytes in progressive supranuclear palsy (PSP). However, the lack of selectivity of [18F]THK-5351 binding to both MAO-B and tau, severely limits its clinical utility as a biomarker. Recently, [18F]SMBT-1 was developed as a selective and reversible MAO-B PET tracer via compound optimization of [18F]THK-5351. In this review, we summarize the strategy underlying molecular imaging of reactive astrogliosis and clinical studies using MAO-B and I2BS PET tracers.
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Affiliation(s)
- Ryuichi Harada
- Department of Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Japan
- *Correspondence: Ryuichi Harada,
| | - Shozo Furumoto
- Cyclotron and Radioisotope Center, Tohoku University, Sendai, Japan
| | - Yukitsuka Kudo
- Department of New Therapeutics Innovation for Alzheimer’s and Dementia, Institute of Development and Aging, Tohoku University, Sendai, Japan
| | - Kazuhiko Yanai
- Department of Pharmacology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Victor L. Villemagne
- Department of Molecular Imaging and Therapy, Austin Health, Melbourne, VIC, Australia
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, United States
| | - Nobuyuki Okamura
- Division of Pharmacology, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, Sendai, Japan
- Nobuyuki Okamura,
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16
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Vainio SK, Dickens AM, Matilainen M, López-Picón FR, Aarnio R, Eskola O, Solin O, Anthony DC, Rinne JO, Airas L, Haaparanta-Solin M. Dimethyl fumarate decreases short-term but not long-term inflammation in a focal EAE model of neuroinflammation. EJNMMI Res 2022; 12:6. [PMID: 35107664 PMCID: PMC8811048 DOI: 10.1186/s13550-022-00878-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 12/27/2021] [Indexed: 12/16/2022] Open
Abstract
Background Dimethyl fumarate (DMF) is an oral immunomodulatory drug used in the treatment of autoimmune diseases. Here, we sought to study whether the effect of DMF can be detected using positron emission tomography (PET) targeting the 18-kDa translocator protein (TSPO) in the focal delayed-type hypersensitivity rat model of multiple sclerosis (fDTH-EAE). The rats were treated orally twice daily from lesion activation (day 0) with either vehicle (tap water with 0.08% Methocel, 200 µL; control group n = 4 (3 after week four)) or 15 mg/kg DMF (n = 4) in 0.08% aqueous Methocel (200 µL) for 8 weeks. The animals were imaged by PET using the TSPO tracer [18F]GE-180 in weeks 0, 1, 2, 4, 8, and 18 following lesion activation, and the non-displaceable binding potential (BPND) was calculated. Immunohistochemical staining for Iba1, CD4, and CD8 was performed in week 18, and in separate cohorts of animals, following 2 or 4 weeks of treatment. Results Using the fDTH-EAE model, DMF reduced the [18F]GE-180 BPND in the DMF-treated animals compared to control animals after 1 week of treatment (two-tailed unpaired t test, p = 0.031), but not in weeks 2, 4, 8, or 18 when imaged in vivo by PET. Immunostaining for Iba1 showed that DMF had no effect on the perilesional volume or the core lesion volume after 2 or 4 weeks of treatment, or at 18 weeks. However, the optical density (OD) measurements of CD4+ staining showed reduced OD in the lesions of the treated rats. Conclusions DMF reduced the microglial activation in the fDTH-EAE model after 1 week of treatment, as detected by PET imaging of the TSPO ligand [18F]GE-180. However, over an extended time course, reduced microglial activation was not observed using [18F]GE-180 or by immunohistochemistry for Iba1+ microglia/macrophages. Additionally, DMF did affect the infiltration of CD4+ and CD8+ T-lymphocytes at the fDTH-EAE lesion. Supplementary Information The online version contains supplementary material available at 10.1186/s13550-022-00878-y. In a focal rat DTH-EAE model of neuroinflammation, dimethyl fumarate decreases the uptake of TSPO PET tracer [18F]GE-180 in the short term. Long-term [18F]GE-180 follow-up did not indicate a treatment effect. Decreased neuroinflammation, CD4+ T cell infiltration, and CD8+ T cell infiltration were detected using immunohistochemistry.
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Affiliation(s)
- S K Vainio
- Turku PET Centre, Preclinical PET Imaging, Preclinical Imaging Laboratory, University of Turku, Tykistökatu 6 A, 20520, Turku, Finland. .,MediCity Research Laboratory, University of Turku, Turku, Finland.
| | - A M Dickens
- Department of Chemistry, University of Turku, Turku, Finland.,Turku Bioscience, Turku, Finland
| | - M Matilainen
- Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland.,Turku PET Centre, University of Turku, Turku, Finland
| | - F R López-Picón
- Turku PET Centre, Preclinical PET Imaging, Preclinical Imaging Laboratory, University of Turku, Tykistökatu 6 A, 20520, Turku, Finland.,MediCity Research Laboratory, University of Turku, Turku, Finland
| | - R Aarnio
- MediCity Research Laboratory, University of Turku, Turku, Finland.,Turku PET Centre, University of Turku, Turku, Finland
| | - O Eskola
- Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, University of Turku, Turku, Finland
| | - O Solin
- Accelerator Laboratory, Åbo Akademi University, Turku, Finland.,Turku PET Centre, Radiopharmaceutical Chemistry Laboratory, University of Turku, Turku, Finland
| | - D C Anthony
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - J O Rinne
- Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland.,Turku PET Centre, University of Turku, Turku, Finland
| | - L Airas
- Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland.,Department of Clinical Medicine, University of Turku, Turku, Finland
| | - M Haaparanta-Solin
- Turku PET Centre, Preclinical PET Imaging, Preclinical Imaging Laboratory, University of Turku, Tykistökatu 6 A, 20520, Turku, Finland.,MediCity Research Laboratory, University of Turku, Turku, Finland
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17
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Jia H, Xie T. Tracers progress for positron emission tomography imaging of glial-related disease. J Biomed Res 2022; 36:321-335. [PMID: 36131689 PMCID: PMC9548440 DOI: 10.7555/jbr.36.20220017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Glial cells play an essential part in the neuron system. They can not only serve as structural blocks in the human brain but also participate in many biological processes. Extensive studies have shown that astrocytes and microglia play an important role in neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, as well as glioma, epilepsy, ischemic stroke, and infections. Positron emission tomography is a functional imaging technique providing molecular-level information before anatomic changes are visible and has been widely used in many above-mentioned diseases. In this review, we focus on the positron emission tomography tracers used in pathologies related to glial cells, such as glioma, Alzheimer's disease, and neuroinflammation.
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Affiliation(s)
- Haoran Jia
- Institute of Radiation Medicine, Fudan University, Shanghai 200032, China
| | - Tianwu Xie
- Institute of Radiation Medicine, Fudan University, Shanghai 200032, China
- Tianwu Xie, Institute of Radiation Medicine, Fudan University, 2094 Xietu Road, Shanghai 200032, China. Tel: +86-21-64048363, E-mail:
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18
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Kaiser L, Holzgreve A, Quach S, Ingrisch M, Unterrainer M, Dekorsy FJ, Lindner S, Ruf V, Brosch-Lenz J, Delker A, Böning G, Suchorska B, Niyazi M, Wetzel CH, Riemenschneider MJ, Stöcklein S, Brendel M, Rupprecht R, Thon N, von Baumgarten L, Tonn JC, Bartenstein P, Ziegler S, Albert NL. Differential Spatial Distribution of TSPO or Amino Acid PET Signal and MRI Contrast Enhancement in Gliomas. Cancers (Basel) 2021; 14:cancers14010053. [PMID: 35008218 PMCID: PMC8750092 DOI: 10.3390/cancers14010053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 12/10/2021] [Accepted: 12/14/2021] [Indexed: 01/14/2023] Open
Abstract
Simple Summary Radiotracers targeting the translocator protein (TSPO) have recently gained substantial interest, since TSPO is overexpressed in malignant gliomas, where it correlates inversely with patient’s survival. The high-affinity TSPO PET ligand [18F]GE180 was found to depict tumor areas with a remarkably high contrast and has been shown to provide non-invasive information on histological tumor grades. Yet, its significance was questioned with the argument, that the high contrast may solely arise from nonspecific accumulation in tissue supplied by leaky vessels. This study aimed to address this question by providing a detailed evaluation of spatial associations between TSPO and amino acid PET with relative contrast enhancement in T1-weighted MRI. The results show that [18F]GE180 contrast does not reflect a disrupted blood–brain barrier (BBB) only and that multi-modal imaging generates complementary information, which may better depict spatial heterogeneity of tumor biology and may be used to individualize the therapy for each patient. Abstract In this study, dual PET and contrast enhanced MRI were combined to investigate their correlation per voxel in patients at initial diagnosis with suspected glioblastoma. Correlation with contrast enhancement (CE) as an indicator of BBB leakage was further used to evaluate whether PET signal is likely caused by BBB disruption alone, or rather attributable to specific binding after BBB passage. PET images with [18F]GE180 and the amino acid [18F]FET were acquired and normalized to healthy background (tumor-to-background ratio, TBR). Contrast enhanced images were normalized voxel by voxel with the pre-contrast T1-weighted MRI to generate relative CE values (rCE). Voxel-wise analysis revealed a high PET signal even within the sub-volumes without detectable CE. No to moderate correlation of rCE with TBR voxel-values and a small overlap as well as a larger distance of the hotspots delineated in rCE and TBR-PET images were detected. In contrast, voxel-wise correlation between both PET modalities was strong for most patients and hotspots showed a moderate overlap and distance. The high PET signal in tumor sub-volumes without CE observed in voxel-wise analysis as well as the discordant hotspots emphasize the specificity of the PET signals and the relevance of combined differential information from dual PET and MRI images.
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Affiliation(s)
- Lena Kaiser
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
- Correspondence:
| | - Adrien Holzgreve
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
| | - Stefanie Quach
- Department of Neurosurgery, University Hospital, LMU Munich, 81377 Munich, Germany; (S.Q.); (N.T.); (L.v.B.); (J.-C.T.)
| | - Michael Ingrisch
- Department of Radiology, University Hospital, LMU Munich, 81377 Munich, Germany; (M.I.); (S.S.)
| | - Marcus Unterrainer
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
- Department of Radiology, University Hospital, LMU Munich, 81377 Munich, Germany; (M.I.); (S.S.)
| | - Franziska J. Dekorsy
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
| | - Simon Lindner
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
| | - Viktoria Ruf
- Center for Neuropathology and Prion Research, LMU Munich, 81377 Munich, Germany; (V.R.); (R.R.)
| | - Julia Brosch-Lenz
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
| | - Astrid Delker
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
| | - Guido Böning
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
| | | | - Maximilian Niyazi
- Department of Radiation Oncology, University Hospital, LMU Munich, 81377 Munich, Germany;
- German Cancer Consortium (DKTK), Partner Site Munich, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Christian H. Wetzel
- Department of Psychiatry and Psychotherapy, University of Regensburg, 93053 Regensburg, Germany;
| | | | - Sophia Stöcklein
- Department of Radiology, University Hospital, LMU Munich, 81377 Munich, Germany; (M.I.); (S.S.)
| | - Matthias Brendel
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
| | - Rainer Rupprecht
- Department of Psychiatry and Psychotherapy, University of Regensburg, 93053 Regensburg, Germany;
| | - Niklas Thon
- Department of Neurosurgery, University Hospital, LMU Munich, 81377 Munich, Germany; (S.Q.); (N.T.); (L.v.B.); (J.-C.T.)
| | - Louisa von Baumgarten
- Department of Neurosurgery, University Hospital, LMU Munich, 81377 Munich, Germany; (S.Q.); (N.T.); (L.v.B.); (J.-C.T.)
| | - Jörg-Christian Tonn
- Department of Neurosurgery, University Hospital, LMU Munich, 81377 Munich, Germany; (S.Q.); (N.T.); (L.v.B.); (J.-C.T.)
- German Cancer Consortium (DKTK), Partner Site Munich, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Peter Bartenstein
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
- German Cancer Consortium (DKTK), Partner Site Munich, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Sibylle Ziegler
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
| | - Nathalie L. Albert
- Department of Nuclear Medicine, University Hospital, LMU Munich, 81377 Munich, Germany; (A.H.); (M.U.); (F.J.D.); (S.L.); (J.B.-L.); (A.D.); (G.B.); (M.B.); (P.B.); (S.Z.); (N.L.A.)
- German Cancer Consortium (DKTK), Partner Site Munich, German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
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Van Camp N, Lavisse S, Roost P, Gubinelli F, Hillmer A, Boutin H. TSPO imaging in animal models of brain diseases. Eur J Nucl Med Mol Imaging 2021; 49:77-109. [PMID: 34245328 PMCID: PMC8712305 DOI: 10.1007/s00259-021-05379-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/25/2021] [Indexed: 12/19/2022]
Abstract
Over the last 30 years, the 18-kDa TSPO protein has been considered as the PET imaging biomarker of reference to measure increased neuroinflammation. Generally assumed to image activated microglia, TSPO has also been detected in endothelial cells and activated astrocytes. Here, we provide an exhaustive overview of the recent literature on the TSPO-PET imaging (i) in the search and development of new TSPO tracers and (ii) in the understanding of acute and chronic neuroinflammation in animal models of neurological disorders. Generally, studies testing new TSPO radiotracers against the prototypic [11C]-R-PK11195 or more recent competitors use models of acute focal neuroinflammation (e.g. stroke or lipopolysaccharide injection). These studies have led to the development of over 60 new tracers during the last 15 years. These studies highlighted that interpretation of TSPO-PET is easier in acute models of focal lesions, whereas in chronic models with lower or diffuse microglial activation, such as models of Alzheimer's disease or Parkinson's disease, TSPO quantification for detection of neuroinflammation is more challenging, mirroring what is observed in clinic. Moreover, technical limitations of preclinical scanners provide a drawback when studying modest neuroinflammation in small brains (e.g. in mice). Overall, this review underlines the value of TSPO imaging to study the time course or response to treatment of neuroinflammation in acute or chronic models of diseases. As such, TSPO remains the gold standard biomarker reference for neuroinflammation, waiting for new radioligands for other, more specific targets for neuroinflammatory processes and/or immune cells to emerge.
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Affiliation(s)
- Nadja Van Camp
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Sonia Lavisse
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Pauline Roost
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Francesco Gubinelli
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Ansel Hillmer
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
- Department of Biomedical Engineering, Yale School of Engineering & Applied Science, New Haven, CT, USA
| | - Hervé Boutin
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Brain and Mental Health, University of Manchester, M13 9PL, Manchester, UK.
- Wolfson Molecular Imaging Centre, University of Manchester, 27 Palatine Road, M20 3LJ, Manchester, UK.
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance & University of Manchester, Manchester, UK.
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Chauveau F, Becker G, Boutin H. Have (R)-[ 11C]PK11195 challengers fulfilled the promise? A scoping review of clinical TSPO PET studies. Eur J Nucl Med Mol Imaging 2021; 49:201-220. [PMID: 34387719 PMCID: PMC8712292 DOI: 10.1007/s00259-021-05425-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 05/19/2021] [Indexed: 12/19/2022]
Abstract
PURPOSE The prototypical TSPO radiotracer (R)-[11C]PK11195 has been used in humans for more than thirty years to visualize neuroinflammation in several pathologies. Alternative radiotracers have been developed to improve signal-to-noise ratio and started to be tested clinically in 2008. Here we examined the scientific value of these "(R)-[11C]PK11195 challengers" in clinical research to determine if they could supersede (R)-[11C]PK11195. METHODS A systematic MEDLINE (PubMed) search was performed (up to end of year 2020) to extract publications reporting TSPO PET in patients with identified pathologies, excluding studies in healthy subjects and methodological studies. RESULTS Of the 288 publications selected, 152 used 13 challengers, and 142 used (R)-[11C]PK11195. Over the last 20 years, the number of (R)-[11C]PK11195 studies remained stable (6 ± 3 per year), but was surpassed by the total number of challenger studies for the last 6 years. In total, 3914 patients underwent a TSPO PET scan, and 47% (1851 patients) received (R)-[11C]PK11195. The 2 main challengers were [11C]PBR28 (24%-938 patients) and [18F]FEPPA (11%-429 patients). Only one-in-ten patients (11%-447) underwent 2 TSPO scans, among whom 40 (1%) were scanned with 2 different TSPO radiotracers. CONCLUSIONS Generally, challengers confirmed disease-specific initial (R)-[11C]PK11195 findings. However, while their better signal-to-noise ratio seems particularly useful in diseases with moderate and widespread neuroinflammation, most challengers present an allelic-dependent (Ala147Thr polymorphism) TSPO binding and genetic stratification is hindering their clinical implementation. As new challengers, insensitive to TSPO human polymorphism, are about to enter clinical evaluation, we propose this systematic review to be regularly updated (living review).
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Affiliation(s)
- Fabien Chauveau
- University of Lyon, Lyon Neuroscience Research Center (CRNL), CNRS UMR5292, INSERM U1028, University Lyon 1, Lyon, France.
| | - Guillaume Becker
- GIGA - CRC In Vivo Imaging, University Liege, Liege, Belgium
- University of Lyon, CarMeN Laboratory, INSERM U1060, University Lyon 1, Hospices Civils Lyon, Lyon, France
| | - Hervé Boutin
- Faculty of Biology Medicine and Health, Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK.
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK.
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance & University of Manchester, Manchester, UK.
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21
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Lee SH, Denora N, Laquintana V, Mangiatordi GF, Lopedota A, Lopalco A, Cutrignelli A, Franco M, Delre P, Song IH, Kim HW, Kim SB, Park HS, Kim K, Lee SY, Youn H, Lee BC, Kim SE. Radiosynthesis and characterization of [ 18F]BS224: a next-generation TSPO PET ligand insensitive to the rs6971 polymorphism. Eur J Nucl Med Mol Imaging 2021; 49:110-124. [PMID: 34783879 PMCID: PMC8712300 DOI: 10.1007/s00259-021-05617-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 11/03/2021] [Indexed: 01/03/2023]
Abstract
PURPOSE Translocator protein 18-kDa (TSPO) positron emission tomography (PET) is a valuable tool to detect neuroinflammed areas in a broad spectrum of neurodegenerative diseases. However, the clinical application of second-generation TSPO ligands as biomarkers is limited because of the presence of human rs6971 polymorphism that affects their binding. Here, we describe the ability of a new TSPO ligand, [18F]BS224, to identify abnormal TSPO expression in neuroinflammation independent of the rs6971 polymorphism. METHODS An in vitro competitive inhibition assay of BS224 was conducted with [3H]PK 11195 using membrane proteins isolated from 293FT cells expressing TSPO-wild type (WT) or TSPO-mutant A147T (Mut), corresponding to a high-affinity binder (HAB) and low-affinity binder (LAB), respectively. Molecular docking was performed to investigate the interaction of BS224 with the binding sites of rat TSPO-WT and TSPO-Mut. We synthesized a new 18F-labeled imidazopyridine acetamide ([18F]BS224) using boronic acid pinacol ester 6 or iodotoluene tosylate precursor 7, respectively, via aromatic 18F-fluorination. Dynamic PET scanning was performed up to 90 min after the injection of [18F]BS224 to healthy mice, and PET imaging data were obtained to estimate its absorbed doses in organs. To evaluate in vivo TSPO-specific uptake of [18F]BS224, lipopolysaccharide (LPS)-induced inflammatory and ischemic stroke rat models were used. RESULTS BS224 exhibited a high affinity (Ki = 0.51 nM) and selectivity for TSPO. The ratio of IC50 values of BS224 for LAB to that for HAB indicated that the TSPO binding affinity of BS224 has low binding sensitivity to the rs6971 polymorphism and it was comparable to that of PK 11195, which is not sensitive to the polymorphism. Docking simulations showed that the binding mode of BS224 is not affected by the A147T mutation and consequently supported the observed in vitro selectivity of [18F]BS224 regardless of polymorphisms. With optimal radiochemical yield (39 ± 6.8%, decay-corrected) and purity (> 99%), [18F]BS224 provided a clear visible image of the inflammatory lesion with a high signal-to-background ratio in both animal models (BPND = 1.43 ± 0.17 and 1.57 ± 0.37 in the LPS-induced inflammatory and ischemic stroke rat models, respectively) without skull uptake. CONCLUSION Our results suggest that [18F]BS224 may be a promising TSPO ligand to gauge neuroinflammatory disease-related areas in a broad range of patients irrespective of the common rs6971 polymorphism.
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Affiliation(s)
- Sang Hee Lee
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826 Republic of Korea
| | - Nunzio Denora
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Valentino Laquintana
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | | | - Angela Lopedota
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Antonio Lopalco
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Annalisa Cutrignelli
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Massimo Franco
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Pietro Delre
- Institute of Crystallography, National Research Council, Via G. Amendola 122/O, 70126 Bari, Italy
- Department of Chemistry, University of Bari “A. Moro”, Via E. Orabona, 4, 70125 Bari, Italy
| | - In Ho Song
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
| | - Hye Won Kim
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826 Republic of Korea
| | - Su Bin Kim
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826 Republic of Korea
| | - Hyun Soo Park
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
| | - Kyungmin Kim
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul, 03080 Republic of Korea
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, 03080 Republic of Korea
- Laboratory of Molecular Imaging and Therapy, Cancer Research Institute, Seoul National University College of Medicine, Seoul, 03080 Republic of Korea
| | - Seok-Yong Lee
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul, 03080 Republic of Korea
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, 03080 Republic of Korea
- Laboratory of Molecular Imaging and Therapy, Cancer Research Institute, Seoul National University College of Medicine, Seoul, 03080 Republic of Korea
| | - Hyewon Youn
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul, 03080 Republic of Korea
- Laboratory of Molecular Imaging and Therapy, Cancer Research Institute, Seoul National University College of Medicine, Seoul, 03080 Republic of Korea
| | - Byung Chul Lee
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Center for Nanomolecular Imaging and Innovative Drug Development, Advanced Institutes of Convergence Technology, Suwon, 16229 Republic of Korea
| | - Sang Eun Kim
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Center for Nanomolecular Imaging and Innovative Drug Development, Advanced Institutes of Convergence Technology, Suwon, 16229 Republic of Korea
- Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826 Republic of Korea
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Li J, Shao D, Jiang D, Huang Q, Guan Y, Lai B, Zhao J, Hua F, Xie F. Alteration of neuroinflammation detected by 18F-GE180 PET imaging in place-conditioned rats with morphine withdrawal. EJNMMI Res 2021; 11:103. [PMID: 34637020 PMCID: PMC8511235 DOI: 10.1186/s13550-021-00849-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 09/28/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Accumulating evidence indicates that neuroinflammation (NI) significantly contributes to drug addiction, but the conversion of NI after drug withdrawal is not clear. Here, we conducted 18F-flutriciclamide (GE180) positron emission tomography (PET) imaging to investigate the conversion of NI during drug withdrawal and conditioning-induced aversion by measuring the change in microglial activation with 18F-GE180. METHODS Twelve male adult Sprague-Dawley rats were subjected to morphine withdrawal by the administration of naloxone, and six of them were used to model conditioned place aversion (CPA). 18F-GE180 PET imaging was performed for 11 rats on the last day of the morphine treatment phase and for 10 rats on the response assessment phase of the behavior conditioning procedure. A 18F-GE180 template was established for spatial normalization of each individual image, and the differential 18F-GE180 uptakes between the drug withdrawal (DW) group and the drug addiction (DA) group, the CPA group and the DA group, and the CPA group and the DW group were compared by a voxel-wise two-sample t test using SPM8. RESULTS Both the DW group and the CPA group spent less time in the conditioning cage during the post-test phase compared with the pretest phase, but only the difference in the CPA group was significant (63.2 ± 34.6 vs. - 159.53 ± 22.02, P < 0.005). Compared with the DA group, the uptake of 18F-GE180 increased mainly in the hippocampus, visual cortex, thalamus and midbrain regions and decreased mainly in the sensory-related cortices after the administration of naloxone in both the DW and CPA groups. Increased 18F-GE180 uptake was only observed in the mesolimbic regions after conditioned aversion compared with the DW group. CONCLUSION In morphine-dependent rats, Neuroinflammation (NI) became more severe in the addiction-involved brain regions but remitted in the sensory-related brain regions after the administration of naloxone, and this NI induced by withdrawal was further aggravated after conditioned aversion formation thus may help to consolidate the withdrawal memory.
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Affiliation(s)
- Junpeng Li
- PET Center, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - Da Shao
- Collaborative Innovation Center for Brain Science, School of Basic Medical Sciences and Institutes of Brain Science, Fudan University, Shanghai, 200032, China.,Research Center of Translation Medicine, Shanghai Children's Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Donglang Jiang
- PET Center, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - Qi Huang
- PET Center, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - Yihui Guan
- PET Center, Huashan Hospital, Fudan University, Shanghai, 200040, China
| | - Bin Lai
- Collaborative Innovation Center for Brain Science, School of Basic Medical Sciences and Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Jun Zhao
- Department of Nuclear Medicine, Dongfang Hospital, Tongji University, Shanghai, 200120, China.
| | - Fengchun Hua
- Department of Nuclear Medicine, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, 200032, China.
| | - Fang Xie
- PET Center, Huashan Hospital, Fudan University, Shanghai, 200040, China.
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Direct Comparison of [ 18F]F-DPA with [ 18F]DPA-714 and [ 11C]PBR28 for Neuroinflammation Imaging in the same Alzheimer's Disease Model Mice and Healthy Controls. Mol Imaging Biol 2021; 24:157-166. [PMID: 34542805 PMCID: PMC8760190 DOI: 10.1007/s11307-021-01646-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 07/22/2021] [Accepted: 08/23/2021] [Indexed: 11/02/2022]
Abstract
PURPOSE In this study we compared the recently developed TSPO tracer [18F]F-DPA, with [18F]DPA-714 and [11C]PBR28 by performing in vivo PET imaging on the same Alzheimer's disease mouse model APP/PS1-21 (TG) and wild-type (WT) mice with all three radiotracers. PROCEDURES To compare the radiotracer uptake, percentage of injected dose/mL (%ID/mL), standardized uptake value ratios to cerebellum (SUVRCB), and voxel-wise analyses were performed. RESULTS The peak uptake of [18F]F-DPA was higher than 4.3% ID/mL, while [18F]DPA-714 reached just over 3% ID/mL, and [11C]PBR28 was over 4% ID/mL in only one brain region in the WT mice. The peak/60-min uptake ratios of [18F]F-DPA were significantly higher (p < 0.001) than those of [18F]DPA-714 and [11C]PBR28. The differences in [18F]F-DPA SUVRCB between WT and TG mice were highly significant (p < 0.001) in the three studied time periods after injection. [18F]DPA-714 uptake was significantly higher in TG mice starting in the 20-40-min timeframe and increased thereafter, whereas [11C]PBR28 uptake became significant at 10-20 min (p < 0.05). The voxel-wise analysis confirmed the differences between the radiotracers. CONCLUSIONS [18F]F-DPA displays higher brain uptake, higher TG-to-WT SUVRCB ratios, and faster clearance than [18F]DPA-714 and [11C]PBR28, and could prove useful for detecting low levels of inflammation and allow for shorter dynamic PET scans.
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Zhou R, Ji B, Kong Y, Qin L, Ren W, Guan Y, Ni R. PET Imaging of Neuroinflammation in Alzheimer's Disease. Front Immunol 2021; 12:739130. [PMID: 34603323 PMCID: PMC8481830 DOI: 10.3389/fimmu.2021.739130] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 08/27/2021] [Indexed: 12/15/2022] Open
Abstract
Neuroinflammation play an important role in Alzheimer's disease pathogenesis. Advances in molecular imaging using positron emission tomography have provided insights into the time course of neuroinflammation and its relation with Alzheimer's disease central pathologies in patients and in animal disease models. Recent single-cell sequencing and transcriptomics indicate dynamic disease-associated microglia and astrocyte profiles in Alzheimer's disease. Mitochondrial 18-kDa translocator protein is the most widely investigated target for neuroinflammation imaging. New generation of translocator protein tracers with improved performance have been developed and evaluated along with tau and amyloid imaging for assessing the disease progression in Alzheimer's disease continuum. Given that translocator protein is not exclusively expressed in glia, alternative targets are under rapid development, such as monoamine oxidase B, matrix metalloproteinases, colony-stimulating factor 1 receptor, imidazoline-2 binding sites, cyclooxygenase, cannabinoid-2 receptor, purinergic P2X7 receptor, P2Y12 receptor, the fractalkine receptor, triggering receptor expressed on myeloid cells 2, and receptor for advanced glycation end products. Promising targets should demonstrate a higher specificity for cellular locations with exclusive expression in microglia or astrocyte and activation status (pro- or anti-inflammatory) with highly specific ligand to enable in vivo brain imaging. In this review, we summarised recent advances in the development of neuroinflammation imaging tracers and provided an outlook for promising targets in the future.
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Affiliation(s)
- Rong Zhou
- Department of Nephrology, Yangpu Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Bin Ji
- Department of Radiopharmacy and Molecular Imaging, School of Pharmacy, Fudan University, Shanghai, China
| | - Yanyan Kong
- Positron Emission Tomography (PET) Center, Huashan Hospital, Fudan University, Shanghai, China
| | - Limei Qin
- Inner Mongolia Baicaotang Qin Chinese Mongolia Hospital, Hohhot, China
| | - Wuwei Ren
- School of Information Science and Technology, Shanghaitech University, Shanghai, China
| | - Yihui Guan
- Positron Emission Tomography (PET) Center, Huashan Hospital, Fudan University, Shanghai, China
| | - Ruiqing Ni
- Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
- Institute for Biomedical Engineering, University of Zurich & Eidgenössische Technische Hochschule Zürich (ETH Zurich), Zurich, Switzerland
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25
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Feasibility of TSPO-Specific Positron Emission Tomography Radiotracer for Evaluating Paracetamol-Induced Liver Injury. Diagnostics (Basel) 2021; 11:diagnostics11091661. [PMID: 34574002 PMCID: PMC8467059 DOI: 10.3390/diagnostics11091661] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/06/2021] [Accepted: 09/09/2021] [Indexed: 01/16/2023] Open
Abstract
Macrophages are activated during the early phase of paracetamol-induced liver injury (PLI). [18F]GE180 is a radiolabeled ligand that recognizes the macrophage translocator protein (TSPO). In this study, we evaluated the feasibility of a TSPO-specific radiotracer in a rat model of PLI. A rat model of liver injury was induced by intraperitoneal administration of paracetamol. [18F]GE180 positron emission tomography (PET) images were obtained after 24 h. The maximal and mean standardized uptake values (SUVmax and SUVav) of the liver and serum biomarker levels were examined. The TSPO expression level was examined using real-time polymerase chain reaction and Western blot analysis. [18F]GE180 hepatic uptake in the PLI group was significantly higher than that in the control group (SUVmax p = 0.001; SUVav p = 0.005). Both mRNA and protein TSPO expression levels were higher in the PLI group. The mRNA expression level of TSPO was significantly correlated with [18F]GE180 hepatic uptake in both groups (SUVmax p = 0.019; SUVav p = 0.007). [18F]GE180 hepatic uptake in the PLI group showed a significant positive correlation with ALT24 and ALT48 (ALT24 p = 0.016; ALT48p = 0.002). [18F]GE180 enabled visualization of PLI through TSPO overexpression. Our results support the potential utility of hepatic uptake by TSPO-PET as a non-invasive imaging biomarker for the early phase of PLI.
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Abstract
PURPOSE OF REVIEW Current therapeutic strategies to mitigate heart failure progression after myocardial infarction involve support of endogenous repair through molecular targets. The capacity for repair varies greatly between individuals. In this review, we will assess how cardiac PET/CT enables precise characterization of early pathogenetic processes which govern ventricle remodeling and progression to heart failure. RECENT FINDINGS Inflammation in the first days after myocardial infarction predicts subsequent functional decline and can influence therapy decisions. The expansion of anti-inflammatory approaches to improve outcomes after myocardial infarction may benefit from noninvasive characterization using imaging. Novel probes also allow visualization of fibroblast transdifferentiation and activation, as a precursor to ventricle remodeling. The expanding arsenal of molecular imaging agents in parallel with new treatment options provides opportunity to harmonize diagnostic imaging with precision therapy.
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Affiliation(s)
- James T Thackeray
- Department of Nuclear Medicine, Hannover Medical School, Neuberg-Str. 1, D-30625, Hannover, Germany.
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27
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Sriranjan RS, Tarkin JM, Evans NR, Le EPV, Chowdhury MM, Rudd JHF. Atherosclerosis imaging using PET: Insights and applications. Br J Pharmacol 2021; 178:2186-2203. [PMID: 31517992 DOI: 10.1111/bph.14868] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 08/02/2019] [Accepted: 08/16/2019] [Indexed: 12/17/2022] Open
Abstract
PET imaging is able to harness biological processes to characterise high-risk features of atherosclerotic plaque prone to rupture. Current radiotracers are able to track inflammation, microcalcification, hypoxia, and neoangiogenesis within vulnerable plaque. 18 F-fluorodeoxyglucose (18 F-FDG) is the most commonly used radiotracer in vascular studies and is employed as a surrogate marker of plaque inflammation. Increasingly, 18 F-FDG and other PET tracers are also being used to provide imaging endpoints in cardiovascular interventional trials. The evolution of novel PET radiotracers, imaging protocols, and hybrid scanners are likely to enable more efficient and accurate characterisation of high-risk plaque. This review explores the role of PET imaging in atherosclerosis with a focus on PET tracers utilised in clinical research and the applications of PET imaging to cardiovascular drug development.
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Affiliation(s)
| | - Jason M Tarkin
- Division of Cardiovascular Medicine, University of Cambridge, Cambridge, UK
| | - Nicholas R Evans
- Division of Cardiovascular Medicine, University of Cambridge, Cambridge, UK
| | - Elizabeth P V Le
- Division of Cardiovascular Medicine, University of Cambridge, Cambridge, UK
| | | | - James H F Rudd
- Division of Cardiovascular Medicine, University of Cambridge, Cambridge, UK
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28
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Song YS, Lee SH, Jung JH, Song IH, Park HS, Moon BS, Kim SE, Lee BC. TSPO Expression Modulatory Effect of Acetylcholinesterase Inhibitor in the Ischemic Stroke Rat Model. Cells 2021; 10:cells10061350. [PMID: 34072449 PMCID: PMC8227181 DOI: 10.3390/cells10061350] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 05/24/2021] [Accepted: 05/26/2021] [Indexed: 12/21/2022] Open
Abstract
We performed in vivo PET imaging with 3-[18F]F-CP118,954 (1) for acetylcholinesterase (AChE) and [18F]fluoromethyl-PBR28-d2 (2) for translocator protein 18-kDa (TSPO) to investigate the inflammatory brain response after stroke. Imaging studies were performed in the middle cerebral artery occlusion (MCAO) Sprague-Dawley rat model for a period of three weeks. The percentage injected dose per tissue weight (%ID/g) of striatum of 1, and cortex of 2 were obtained, respectively. To trace the sequential inflammatory responses, AChE imaging of 1 was done on post-MCAO day 2, after giving cold PK-11195 for 1 day, and TSPO imaging of 2 was carried out on post-MCAO day 11, after giving donepezil for 10 days. AChE activity in the MCAO-lesioned side were significantly higher than that of the contralateral side on day one, and TSPO activity was highest on day 11. TSPO inhibitor, PK-11195 did not affect AChE activity on day two, while AChE inhibitor, donepezil significantly lowered TSPO binding on day 12. Our study demonstrates that AChE level is elevated in the early course of brain ischemia as a trigger for the inflammatory response, and TSPO level is elevated persistently throughout the post-ischemic injury in the brain. Also, the AChE inhibitor may be able to inhibit or delay neurotoxic inflammatory responses and serve as a beneficial treatment option.
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Affiliation(s)
- Yoo Sung Song
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Korea; (Y.S.S.); (S.H.L.); (J.H.J.); (I.H.S.); (H.S.P.)
| | - Sang Hee Lee
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Korea; (Y.S.S.); (S.H.L.); (J.H.J.); (I.H.S.); (H.S.P.)
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 08826, Korea
| | - Jae Ho Jung
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Korea; (Y.S.S.); (S.H.L.); (J.H.J.); (I.H.S.); (H.S.P.)
| | - In Ho Song
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Korea; (Y.S.S.); (S.H.L.); (J.H.J.); (I.H.S.); (H.S.P.)
| | - Hyun Soo Park
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Korea; (Y.S.S.); (S.H.L.); (J.H.J.); (I.H.S.); (H.S.P.)
| | - Byung Seok Moon
- Department of Nuclear Medicine, Ewha Womans University Seoul Hospital, Ewha Womans University College of Medicine, Seoul 07804, Korea;
| | - Sang Eun Kim
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Korea; (Y.S.S.); (S.H.L.); (J.H.J.); (I.H.S.); (H.S.P.)
- Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 08826, Korea
- Center for Nanomolecular Imaging and Innovative Drug Development, Advanced Institutes of Convergence Technology, Suwon 16229, Korea
- Correspondence: (S.E.K.); (B.C.L.); Tel.: +82-31-787-7671 (S.E.K.); +82-31-787-2956 (B.C.L.)
| | - Byung Chul Lee
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam 13620, Korea; (Y.S.S.); (S.H.L.); (J.H.J.); (I.H.S.); (H.S.P.)
- Center for Nanomolecular Imaging and Innovative Drug Development, Advanced Institutes of Convergence Technology, Suwon 16229, Korea
- Correspondence: (S.E.K.); (B.C.L.); Tel.: +82-31-787-7671 (S.E.K.); +82-31-787-2956 (B.C.L.)
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29
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Nikam RM, Yue X, Kandula VV, Paudyal B, Langhans SA, Averill LW, Choudhary AK. Unravelling neuroinflammation in abusive head trauma with radiotracer imaging. Pediatr Radiol 2021; 51:966-970. [PMID: 33999238 DOI: 10.1007/s00247-021-04995-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 12/07/2020] [Accepted: 01/27/2021] [Indexed: 01/07/2023]
Abstract
Abusive head trauma (AHT) is a leading cause of mortality and morbidity in child abuse, with a mortality rate of approximately 25%. In survivors, the prognosis remains dismal, with high prevalence of cerebral palsy, epilepsy and neuropsychiatric disorders. Early and accurate diagnosis of AHT is challenging, both clinically and radiologically, with up to one-third of cases missed on initial examination. Moreover, most of the management in AHT is supportive, reflective of the lack of clear understanding of specific pathogenic mechanisms underlying secondary insult, with approaches targeted toward decreasing intracranial hypertension and reducing cerebral metabolism, cell death and excitotoxicity. Multiple studies have elucidated the role of pro- and anti-inflammatory cytokines and chemokines with upregulation/recruitment of microglia/macrophages, oligodendrocytes and astrocytes in severe traumatic brain injury (TBI). In addition, recent studies in animal models of AHT have demonstrated significant upregulation of microglia, with a potential role of inflammatory cascade contributing to secondary insult. Despite the histological and biochemical evidence, there is a significant dearth of specific imaging approaches to identify this neuroinflammation in AHT. The primary motivation for development of such imaging approaches stems from the need to therapeutically target neuroinflammation and establish its utility in monitoring and prognostication. In the present paper, we discuss the available data suggesting the potential role of neuroinflammation in AHT and role of radiotracer imaging in aiding diagnosis and patient management.
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Affiliation(s)
- Rahul M Nikam
- Department of Medical Imaging, Nemours Alfred I. duPont Hospital for Children, 1600 Rockland Road, Wilmington, DE, 19803, USA. .,Katzin Diagnostic & Research PET/MR Center, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA.
| | - Xuyi Yue
- Katzin Diagnostic & Research PET/MR Center, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Vinay V Kandula
- Department of Medical Imaging, Nemours Alfred I. duPont Hospital for Children, 1600 Rockland Road, Wilmington, DE, 19803, USA
| | - Bishnuhari Paudyal
- Katzin Diagnostic & Research PET/MR Center, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Sigrid A Langhans
- Katzin Diagnostic & Research PET/MR Center, Nemours Alfred I. duPont Hospital for Children, Wilmington, DE, USA
| | - Lauren W Averill
- Department of Medical Imaging, Nemours Alfred I. duPont Hospital for Children, 1600 Rockland Road, Wilmington, DE, 19803, USA
| | - Arabinda K Choudhary
- Department of Radiology, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, USA
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30
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Mahler C, Schumacher AM, Unterrainer M, Kaiser L, Höllbacher T, Lindner S, Havla J, Ertl-Wagner B, Patzig M, Seelos K, Neitzel J, Mäurer M, Krumbholz M, Metz I, Brück W, Stadelmann C, Merkler D, Gass A, Milenkovic V, Bartenstein P, Albert NL, Kümpfel T, Kerschensteiner M. TSPO PET imaging of natalizumab-associated progressive multifocal leukoencephalopathy. Brain 2021; 144:2683-2695. [PMID: 33757118 DOI: 10.1093/brain/awab127] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 02/10/2021] [Accepted: 03/01/2021] [Indexed: 01/31/2023] Open
Abstract
Progressive multifocal leukoencephalopathy (PML) is a severe infection of the central nervous system caused by the polyomavirus JC (JCV) that can occur in multiple sclerosis (MS) patients treated with natalizumab. Clinical management of patients with natalizumab-associated PML is challenging not the least because current imaging tools for the early detection, longitudinal monitoring and differential diagnosis of PML lesions are limited. Here we evaluate whether TSPO positron emission tomography (PET) imaging can be applied to monitor the inflammatory activity of PML lesions over time and differentiate them from MS lesions. For this monocenter pilot study we followed 8 patients with natalizumab-associated PML with PET imaging using the TSPO radioligand [18F]GE-180 combined with frequent 3 T MRI imaging. In addition we compared TSPO PET signals in PML lesions with the signal pattern of MS lesions from 17 independent MS patients. We evaluated the standardized uptake value ratio (SUVR) as well as the morphometry of the TSPO uptake for putative PML and MS lesions areas compared to a radiologically unaffected pseudo-reference region in the cerebrum. Furthermore TSPO expression in situ was immunohistochemically verified by determining the density and cellular identity of TSPO-expressing cells in brain sections from four patients with early natalizumab-associated PML as well as five patients with other forms of PML and six patients with inflammatory demyelinating CNS lesions (clinically isolated syndrome/MS). Histological analysis revealed a reticular accumulation of TSPO expressing phagocytes in PML lesions, while such phagocytes showed a more homogenous distribution in putative MS lesions. TSPO PET imaging showed an enhanced tracer uptake in natalizumab-associated PML lesions that was present from the early to the chronic stages (up to 52 months after PML diagnosis). While gadolinium enhancement on MRI rapidly declined to baseline levels, TSPO tracer uptake followed a slow one phase decay curve. A TSPO-based 3-dimensional diagnostic matrix taking into account the uptake levels as well as the shape and texture of the TSPO signal differentiated more than 96% of PML and MS lesions. Indeed, treatment with rituximab after natalizumab-associated PML in three patients did not affect tracer uptake in the assigned PML lesions but reverted tracer uptake to baseline in the assigned active MS lesions. Taken together our study suggests that TSPO PET imaging can reveal CNS inflammation in natalizumab-associated PML. TSPO PET may facilitate longitudinal monitoring of disease activity and help to distinguish recurrent MS activity from PML progression.
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Affiliation(s)
- Christoph Mahler
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany.,Biomedical Center (BMC), Medical Faculty, Ludwig-Maximilians-Universität Munich, Martinsried, Germany
| | - Adrian-Minh Schumacher
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany.,Biomedical Center (BMC), Medical Faculty, Ludwig-Maximilians-Universität Munich, Martinsried, Germany
| | - Marcus Unterrainer
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Lena Kaiser
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Thomas Höllbacher
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Simon Lindner
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Joachim Havla
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany.,Biomedical Center (BMC), Medical Faculty, Ludwig-Maximilians-Universität Munich, Martinsried, Germany
| | - Birgit Ertl-Wagner
- Institute of Clinical Radiology, University Hospital Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Maximilian Patzig
- Institute of Neuroradiology, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Klaus Seelos
- Institute of Neuroradiology, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Julia Neitzel
- Institute for Stroke and Dementia Research, Ludwig-Maximilians-Universität Munich, Munich, Germany
| | | | - Markus Krumbholz
- Department of Neurology & Stroke and Hertie-Institute for Clinical Brain Research, Eberhard Karl University of Tübingen, Tübingen, Germany
| | - Imke Metz
- Institute of Neuropathology, University Medical Center Göttingen, Göttingen, Germany
| | - Wolfgang Brück
- Institute of Neuropathology, University Medical Center Göttingen, Göttingen, Germany
| | - Christine Stadelmann
- Institute of Neuropathology, University Medical Center Göttingen, Göttingen, Germany
| | - Doron Merkler
- Division of Clinical Pathology, Geneva University Hospital, Geneva, Switzerland.,Department of Pathology and Immunology, University of Geneva, Geneva, Switzerland
| | - Achim Gass
- Department of Neurology, University Hospital Mannheim, Mannheim, Germany
| | - Vladimir Milenkovic
- Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany
| | - Peter Bartenstein
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany.,Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
| | - Nathalie L Albert
- Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany
| | - Tania Kümpfel
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany.,Biomedical Center (BMC), Medical Faculty, Ludwig-Maximilians-Universität Munich, Martinsried, Germany
| | - Martin Kerschensteiner
- Institute of Clinical Neuroimmunology, University Hospital, Ludwig-Maximilians-Universität Munich, Munich, Germany.,Biomedical Center (BMC), Medical Faculty, Ludwig-Maximilians-Universität Munich, Martinsried, Germany.,Munich Cluster of Systems Neurology (SyNergy), Munich, Germany
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31
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Rivière G, Jaipuria G, Andreas LB, Leonov A, Giller K, Becker S, Zweckstetter M. Membrane-embedded TSPO: an NMR view. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:173-180. [PMID: 33354729 PMCID: PMC8071791 DOI: 10.1007/s00249-020-01487-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 10/19/2020] [Accepted: 11/26/2020] [Indexed: 12/21/2022]
Abstract
Translocator Protein (18 kDa) (TSPO) is a mitochondrial transmembrane protein commonly used as a biomarker for neuroinflammation and is also a potential therapeutic target in neurodegenerative diseases. Despite intensive research efforts, the function of TSPO is still largely enigmatic. Deciphering TSPO structure in the native lipid environment is essential to gain insight into its cellular activities and to design improved diagnostic and therapeutic ligands. Here, we discuss the influence of lipid composition on the structure of mammalian TSPO embedded into lipid bilayers on the basis of solid-state NMR experiments. We further highlight that cholesterol can influence both the tertiary and quaternary TSPO structure and also influence TSPO localization in mitochondria-associated endoplasmic reticulum membranes.
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Affiliation(s)
- Gwladys Rivière
- Senior Research Group of Translational Structural Biology in Dementia, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Von-Siebold-Str. 3a, 37075, Göttingen, Germany
- Department of Neurology, University Medical Center Göttingen, University of Göttingen, Waldweg 33, 37073, Göttingen, Germany
| | - Garima Jaipuria
- Senior Research Group of Translational Structural Biology in Dementia, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Von-Siebold-Str. 3a, 37075, Göttingen, Germany
- Department of Neurology, University Medical Center Göttingen, University of Göttingen, Waldweg 33, 37073, Göttingen, Germany
| | - Loren B Andreas
- Department of NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Andrei Leonov
- Department of NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Karin Giller
- Department of NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Stefan Becker
- Department of NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Markus Zweckstetter
- Senior Research Group of Translational Structural Biology in Dementia, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Von-Siebold-Str. 3a, 37075, Göttingen, Germany.
- Department of Neurology, University Medical Center Göttingen, University of Göttingen, Waldweg 33, 37073, Göttingen, Germany.
- Department of NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.
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32
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Imaging Inflammation with Positron Emission Tomography. Biomedicines 2021; 9:biomedicines9020212. [PMID: 33669804 PMCID: PMC7922638 DOI: 10.3390/biomedicines9020212] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 01/28/2021] [Accepted: 02/12/2021] [Indexed: 12/19/2022] Open
Abstract
The impact of inflammation on the outcome of many medical conditions such as cardiovascular diseases, neurological disorders, infections, cancer, and autoimmune diseases has been widely acknowledged. However, in contrast to neurological, oncologic, and cardiovascular disorders, imaging plays a minor role in research and management of inflammation. Imaging can provide insights into individual and temporospatial biology and grade of inflammation which can be of diagnostic, therapeutic, and prognostic value. There is therefore an urgent need to evaluate and understand current approaches and potential applications for imaging of inflammation. This review discusses radiotracers for positron emission tomography (PET) that have been used to image inflammation in cardiovascular diseases and other inflammatory conditions with a special emphasis on radiotracers that have already been successfully applied in clinical settings.
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Jones MA, MacCuaig WM, Frickenstein AN, Camalan S, Gurcan MN, Holter-Chakrabarty J, Morris KT, McNally MW, Booth KK, Carter S, Grizzle WE, McNally LR. Molecular Imaging of Inflammatory Disease. Biomedicines 2021; 9:152. [PMID: 33557374 PMCID: PMC7914540 DOI: 10.3390/biomedicines9020152] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/25/2021] [Accepted: 01/31/2021] [Indexed: 02/06/2023] Open
Abstract
Inflammatory diseases include a wide variety of highly prevalent conditions with high mortality rates in severe cases ranging from cardiovascular disease, to rheumatoid arthritis, to chronic obstructive pulmonary disease, to graft vs. host disease, to a number of gastrointestinal disorders. Many diseases that are not considered inflammatory per se are associated with varying levels of inflammation. Imaging of the immune system and inflammatory response is of interest as it can give insight into disease progression and severity. Clinical imaging technologies such as computed tomography (CT) and magnetic resonance imaging (MRI) are traditionally limited to the visualization of anatomical information; then, the presence or absence of an inflammatory state must be inferred from the structural abnormalities. Improvement in available contrast agents has made it possible to obtain functional information as well as anatomical. In vivo imaging of inflammation ultimately facilitates an improved accuracy of diagnostics and monitoring of patients to allow for better patient care. Highly specific molecular imaging of inflammatory biomarkers allows for earlier diagnosis to prevent irreversible damage. Advancements in imaging instruments, targeted tracers, and contrast agents represent a rapidly growing area of preclinical research with the hopes of quick translation to the clinic.
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Affiliation(s)
- Meredith A. Jones
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK 73019, USA; (M.A.J.); (W.M.M.); (A.N.F.)
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA; (J.H.-C.); (K.T.M.); (M.W.M.); (K.K.B.); (S.C.)
| | - William M. MacCuaig
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK 73019, USA; (M.A.J.); (W.M.M.); (A.N.F.)
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA; (J.H.-C.); (K.T.M.); (M.W.M.); (K.K.B.); (S.C.)
| | - Alex N. Frickenstein
- Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK 73019, USA; (M.A.J.); (W.M.M.); (A.N.F.)
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA; (J.H.-C.); (K.T.M.); (M.W.M.); (K.K.B.); (S.C.)
| | - Seda Camalan
- Department of Internal Medicine, Wake Forest Baptist Health, Winston-Salem, NC 27157, USA; (S.C.); (M.N.G.)
| | - Metin N. Gurcan
- Department of Internal Medicine, Wake Forest Baptist Health, Winston-Salem, NC 27157, USA; (S.C.); (M.N.G.)
| | - Jennifer Holter-Chakrabarty
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA; (J.H.-C.); (K.T.M.); (M.W.M.); (K.K.B.); (S.C.)
- Department of Medicine, University of Oklahoma, Oklahoma City, OK 73104, USA
| | - Katherine T. Morris
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA; (J.H.-C.); (K.T.M.); (M.W.M.); (K.K.B.); (S.C.)
- Department of Surgery, University of Oklahoma, Oklahoma City, OK 73104, USA
| | - Molly W. McNally
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA; (J.H.-C.); (K.T.M.); (M.W.M.); (K.K.B.); (S.C.)
| | - Kristina K. Booth
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA; (J.H.-C.); (K.T.M.); (M.W.M.); (K.K.B.); (S.C.)
- Department of Surgery, University of Oklahoma, Oklahoma City, OK 73104, USA
| | - Steven Carter
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA; (J.H.-C.); (K.T.M.); (M.W.M.); (K.K.B.); (S.C.)
- Department of Surgery, University of Oklahoma, Oklahoma City, OK 73104, USA
| | - William E. Grizzle
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294, USA;
| | - Lacey R. McNally
- Stephenson Cancer Center, University of Oklahoma, Oklahoma City, OK 73104, USA; (J.H.-C.); (K.T.M.); (M.W.M.); (K.K.B.); (S.C.)
- Department of Surgery, University of Oklahoma, Oklahoma City, OK 73104, USA
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Zhang L, Hu K, Shao T, Hou L, Zhang S, Ye W, Josephson L, Meyer JH, Zhang MR, Vasdev N, Wang J, Xu H, Wang L, Liang SH. Recent developments on PET radiotracers for TSPO and their applications in neuroimaging. Acta Pharm Sin B 2021; 11:373-393. [PMID: 33643818 PMCID: PMC7893127 DOI: 10.1016/j.apsb.2020.08.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/15/2020] [Accepted: 07/29/2020] [Indexed: 12/12/2022] Open
Abstract
The 18 kDa translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor, is predominately localized to the outer mitochondrial membrane in steroidogenic cells. Brain TSPO expression is relatively low under physiological conditions, but is upregulated in response to glial cell activation. As the primary index of neuroinflammation, TSPO is implicated in the pathogenesis and progression of numerous neuropsychiatric disorders and neurodegenerative diseases, including Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), multiple sclerosis (MS), major depressive disorder (MDD) and obsessive compulsive disorder (OCD). In this context, numerous TSPO-targeted positron emission tomography (PET) tracers have been developed. Among them, several radioligands have advanced to clinical research studies. In this review, we will overview the recent development of TSPO PET tracers, focusing on the radioligand design, radioisotope labeling, pharmacokinetics, and PET imaging evaluation. Additionally, we will consider current limitations, as well as translational potential for future application of TSPO radiopharmaceuticals. This review aims to not only present the challenges in current TSPO PET imaging, but to also provide a new perspective on TSPO targeted PET tracer discovery efforts. Addressing these challenges will facilitate the translation of TSPO in clinical studies of neuroinflammation associated with central nervous system diseases.
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Key Words
- AD, Alzheimer's disease
- ALS, amyotrophic lateral sclerosis
- AMPA, α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid
- ANT, adenine nucleotide transporter
- Am, molar activities
- BBB, blood‒brain barrier
- BMSC, bone marrow stromal cells
- BP, binding potential
- BPND, non-displaceable binding potential
- BcTSPO, Bacillus cereus TSPO
- CBD, corticobasal degeneration
- CNS disorders
- CNS, central nervous system
- CRAC, cholesterol recognition amino acid consensus sequence
- DLB, Lewy body dementias
- EP, epilepsy
- FTD, frontotemporal dementia
- HAB, high-affinity binding
- HD, Huntington's disease
- HSE, herpes simplex encephalitis
- IMM, inner mitochondrial membrane
- KA, kainic acid
- LAB, low-affinity binding
- LPS, lipopolysaccharide
- MAB, mixed-affinity binding
- MAO-B, monoamine oxidase B
- MCI, mild cognitive impairment
- MDD, major depressive disorder
- MMSE, mini-mental state examination
- MRI, magnetic resonance imaging
- MS, multiple sclerosis
- MSA, multiple system atrophy
- Microglial activation
- NAA/Cr, N-acetylaspartate/creatine
- Neuroinflammation
- OCD, obsessive compulsive disorder
- OMM, outer mitochondrial membrane
- P2X7R, purinergic receptor P2X7
- PAP7, RIa-associated protein
- PBR, peripheral benzodiazepine receptor
- PCA, posterior cortical atrophy
- PD, Parkinson's disease
- PDD, PD dementia
- PET, positron emission tomography
- PKA, protein kinase A
- PRAX-1, PBR-associated protein 1
- PSP, progressive supranuclear palsy
- Positron emission tomography (PET)
- PpIX, protoporphyrin IX
- QA, quinolinic acid
- RCYs, radiochemical yields
- ROS, reactive oxygen species
- RRMS, relapsing remitting multiple sclerosis
- SA, specific activity
- SAH, subarachnoid hemorrhage
- SAR, structure–activity relationship
- SCIDY, spirocyclic iodonium ylide
- SNL, selective neuronal loss
- SNR, signal to noise ratio
- SUV, standard uptake volume
- SUVR, standard uptake volume ratio
- TBAH, tetrabutyl ammonium hydroxide
- TBI, traumatic brain injury
- TLE, temporal lobe epilepsy
- TSPO
- TSPO, translocator protein
- VDAC, voltage-dependent anion channel
- VT, distribution volume
- d.c. RCYs, decay-corrected radiochemical yields
- dMCAO, distal middle cerebral artery occlusion
- fP, plasma free fraction
- n.d.c. RCYs, non-decay-corrected radiochemical yields
- p.i., post-injection
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Cipollina G, Davari Serej A, Di Nolfi G, Gazzano A, Marsala A, Spatafora MG, Peviani M. Heterogeneity of Neuroinflammatory Responses in Amyotrophic Lateral Sclerosis: A Challenge or an Opportunity? Int J Mol Sci 2020; 21:E7923. [PMID: 33113845 PMCID: PMC7662281 DOI: 10.3390/ijms21217923] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/21/2020] [Accepted: 10/22/2020] [Indexed: 02/06/2023] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a complex pathology: (i) the neurodegeneration is chronic and progressive; it starts focally in specific central nervous system (CNS) areas and spreads to different districts; (ii) multiple cell types further than motor neurons (i.e., glial/immune system cells) are actively involved in the disease; (iii) both neurosupportive and neurotoxic neuroinflammatory responses were identified. Microglia cells (a key player of neuroinflammation in the CNS) attracted great interest as potential target cell population that could be modulated to counteract disease progression, at least in preclinical ALS models. However, the heterogeneous/multifaceted microglia cell responses occurring in different CNS districts during the disease represent a hurdle for clinical translation of single-drug therapies. To address this issue, over the past ten years, several studies attempted to dissect the complexity of microglia responses in ALS. In this review, we shall summarize these results highlighting how the heterogeneous signature displayed by ALS microglia reflects not only the extent of neuronal demise in different regions of the CNS, but also variable engagement in the attempts to cope with the neuronal damage. We shall discuss novel avenues opened by the advent of single-cell and spatial transcriptomics technologies, underlining the potential for discovery of novel therapeutic targets, as well as more specific diagnostic/prognostic not-invasive markers of neuroinflammation.
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Affiliation(s)
| | | | | | | | | | | | - Marco Peviani
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, via Ferrata 9, 27100 Pavia, Italy; (G.C.); (A.D.S.); (G.D.N.); (A.G.); (A.M.); (M.G.S.)
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Longitudinal translocator protein-18 kDa-positron emission tomography imaging of peripheral and central myeloid cells in a mouse model of complex regional pain syndrome. Pain 2020; 160:2136-2148. [PMID: 31095093 PMCID: PMC6527343 DOI: 10.1097/j.pain.0000000000001607] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Supplemental Digital Content is Available in the Text. Longitudinal positron emission tomography of translocator protein-18 kDa revealed early central, and persistent peripheral, myeloid activation in a mouse tibial fracture model of complex regional pain syndrome. Complex regional pain syndrome (CRPS) is a severely disabling disease characterized by pain, temperature changes, motor dysfunction, and edema that most often occurs as an atypical response to a minor surgery or fracture. Inflammation involving activation and recruitment of innate immune cells, including both peripheral and central myeloid cells (ie, macrophages and microglia, respectively), is a key feature of CRPS. However, the exact role and time course of these cellular processes relative to the known acute and chronic phases of the disease are not fully understood. Positron emission tomography (PET) of translocator protein-18 kDa (TSPO) is a method for noninvasively tracking these activated innate immune cells. Here, we reveal the temporal dynamics of peripheral and central inflammatory responses over 20 weeks in a tibial fracture/casting mouse model of CRPS through longitudinal TSPO-PET using [18F]GE-180. Positron emission tomography tracer uptake quantification in the tibia revealed increased peripheral inflammation as early as 2 days after fracture and lasting 7 weeks. Centralized inflammation was detected in the spinal cord and brain of fractured mice at 7 and 21 days after injury. Spinal cord tissue immunofluorescent staining revealed TSPO expression in microglia (CD11b+) at 7 days but was restricted mainly to endothelial cells (PECAM1+) at baseline and 7 weeks. Our data suggest early and persistent peripheral myeloid cell activation and transient central microglial activation are limited to the acute phase of CRPS. Moreover, we show that TSPO-PET can be used to noninvasively monitor the spatiotemporal dynamics of myeloid cell activation in CRPS progression with potential to inform disease phase–specific therapeutics.
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Lepelletier FX, Vandesquille M, Asselin MC, Prenant C, Robinson AC, Mann DMA, Green M, Barnett E, Banister SD, Mottinelli M, Mesangeau C, McCurdy CR, Fricke IB, Jacobs AH, Kassiou M, Boutin H. Evaluation of 18F-IAM6067 as a sigma-1 receptor PET tracer for neurodegeneration in vivo in rodents and in human tissue. Theranostics 2020; 10:7938-7955. [PMID: 32724451 PMCID: PMC7381740 DOI: 10.7150/thno.47585] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 06/06/2020] [Indexed: 01/30/2023] Open
Abstract
The sigma 1 receptor (S1R) is widely expressed in the CNS and is mainly located on the endoplasmic reticulum. The S1R is involved in the regulation of many neurotransmission systems and, indirectly, in neurodegenerative diseases. The S1R may therefore represent an interesting neuronal biomarker in neurodegenerative diseases such as Parkinson's (PD) or Alzheimer's diseases (AD). Here we present the characterisation of the S1R-specific 18F-labelled tracer 18F-IAM6067 in two animal models and in human brain tissue. Methods: Wistar rats were used for PET-CT imaging (60 min dynamic acquisition) and metabolite analysis (1, 2, 5, 10, 20, 60 min post-injection). To verify in vivo selectivity, haloperidol, BD1047 (S1R ligand), CM398 (S2R ligand) and SB206553 (5HT2B/C antagonist) were administrated for pre-saturation studies. Excitotoxic lesions induced by intra-striatal injection of AMPA were also imaged by 18F-IAM6067 PET-CT to test the sensitivity of the methods in a well-established model of neuronal loss. Tracer brain uptake was also verified by autoradiography in rats and in a mouse model of PD (intrastriatal 6-hydroxydopamine (6-OHDA) unilateral lesion). Finally, human cortical binding was investigated by autoradiography in three groups of subjects (control subjects with Braak ≤2, and AD patients, Braak >2 & ≤4 and Braak >4 stages). Results: We demonstrate that despite rapid peripheral metabolism of 18F-IAM6067, radiolabelled metabolites were hardly detected in brain samples. Brain uptake of 18F-IAM6067 showed differences in S1R anatomical distribution, namely from high to low uptake: pons-raphe, thalamus medio-dorsal, substantia nigra, hypothalamus, cerebellum, cortical areas and striatum. Pre-saturation studies showed 79-90% blockade of the binding in all areas of the brain indicated above except with the 5HT2B/C antagonist SB206553 and S2R ligand CM398 which induced no significant blockade, indicating good specificity of 18F-IAM6067 for S1Rs. No difference between ipsi- and contralateral sides of the brain in the mouse model of PD was detected. AMPA lesion induced a significant 69% decrease in 18F-IAM6067 uptake in the globus pallidus matching the neuronal loss as measured by NeuN, but only a trend to decrease (-16%) in the caudate putamen despite a significant 91% decrease in neuronal count. Moreover, no difference in the human cortical binding was shown between AD groups and controls. Conclusion: This work shows that 18F-IAM6067 is a specific and selective S1R radiotracer. The absence or small changes in S1R detected here in animal models and human tissue warrants further investigations and suggests that S1R might not be the anticipated ideal biomarker for neuronal loss in neurodegenerative diseases such as AD and PD.
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Affiliation(s)
- François-Xavier Lepelletier
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
| | - Matthias Vandesquille
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
| | - Marie-Claude Asselin
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
- Faculty of Biology, Medicine and Health, School of Health Sciences, Division of Informatics, Imaging and Data Sciences, University of Manchester, Manchester, United Kingdom
| | - Christian Prenant
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
| | - Andrew C Robinson
- Salford Royal NHS Foundation Trust, Department of Clinical & Cognitive Neurosciences, Clinical Sciences Building, Salford, United Kingdom
| | - David M A Mann
- Salford Royal NHS Foundation Trust, Department of Clinical & Cognitive Neurosciences, Clinical Sciences Building, Salford, United Kingdom
| | - Michael Green
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
- Faculty of Biology, Medicine and Health, School of Health Sciences, Division of Informatics, Imaging and Data Sciences, University of Manchester, Manchester, United Kingdom
| | - Elizabeth Barnett
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
- Faculty of Biology, Medicine and Health, School of Health Sciences, Division of Informatics, Imaging and Data Sciences, University of Manchester, Manchester, United Kingdom
| | | | - Marco Mottinelli
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610, USA
| | - Christophe Mesangeau
- Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677, USA
| | - Christopher R McCurdy
- Department of Medicinal Chemistry, College of Pharmacy, University of Florida, Gainesville, FL 32610, USA
- UF Translational Drug Development Core, University of Florida, Gainesville, FL 32610, USA
| | - Inga B Fricke
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms-Universität (WWU), Münster, Germany
| | - Andreas H. Jacobs
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms-Universität (WWU), Münster, Germany
- Department of Geriatrics and Neurology, Johanniter Hospital, Bonn, Germany
| | - Michael Kassiou
- School of Chemistry, The University of Sydney, Sydney, Australia
| | - Hervé Boutin
- Faculty of Biology, Medicine and Health, School of Biological Sciences, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, United Kingdom
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Sridharan S, Raffel J, Nandoskar A, Record C, Brooks DJ, Owen D, Sharp D, Muraro PA, Gunn R, Nicholas R. Confirmation of Specific Binding of the 18-kDa Translocator Protein (TSPO) Radioligand [ 18F]GE-180: a Blocking Study Using XBD173 in Multiple Sclerosis Normal Appearing White and Grey Matter. Mol Imaging Biol 2020; 21:935-944. [PMID: 30796709 DOI: 10.1007/s11307-019-01323-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
PURPOSE Measurements of non-displaceable binding (VND) of positron emission tomography (PET) ligands are not often made in vivo in humans because they require ligands to displace binding to target receptors and there are few readily available, safe ones to use. A technique to measure VND for ligands for the 18-kDa translocator protein (TSPO) has recently been developed which compares the total volume of distribution (VT) before and after administration of the TSPO ligand XBD173. Here, we used XBD173 with an occupancy plot to quantify VND for two TSPO radiotracers, [18F]GE-180 and [11C]PBR28, in cohorts of people with multiple sclerosis (MS). Additionally, we compared plots of subjects carrying high (HAB) or mixed binding (MAB) affinity polymorphisms of TSPO to estimate VND without receptor blockade. PROCEDURES Twelve people with MS underwent baseline MRI and 90-min dynamic [18F]GE-180 PET or [11C]PBR28 PET (n = 6; three HAB, three MAB each). Arterial blood sampling was used to generate plasma input functions for the two-tissue compartment model. VND was calculated using two independent methods: the occupancy plot (by modelling the differences in signal post XBD173) and the polymorphism plot (by modelling the differences in signal across presence and absence of rs6971 genotypes). RESULTS Whole brain VT (mean ± standard deviation) was 0.29 ± 0.17 ml/cm3 for [18F]GE-180 and 5.01 ± 1.88 ml/cm3 for [11C]PBR28. Using the occupancy and polymorphism plots respectively, VND for [18F]GE-180 was 0.11 ml/cm3 (95 % CI = 0.02, 0.16) and 0.20 ml/cm3 (0.16, 0.34), accounting for, on average, 55 % of VT in the whole brain. For [11C]PBR28, these values were 3.81 ml/cm3 (3.02, 4.21) and 3.49 ml/cm3 (1.38, 4.27), accounting for 67 % of average whole brain VT. CONCLUSIONS Although VT for [18F]GE-180 is low, indicating low brain penetration, half the signal shown by MS subjects reflected specific TSPO binding. VT for [11C]PBR28 was higher and two thirds of the binding was non-specific. No brain ROIs were devoid of specific signal, further confirming that true reference tissue approaches are potentially problematic for estimating TSPO levels.
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Affiliation(s)
- Sujata Sridharan
- Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Burlington Danes Building, Du Cane Road, London, W12 0NN, UK.
| | - Joel Raffel
- Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Burlington Danes Building, Du Cane Road, London, W12 0NN, UK
| | - Ashwini Nandoskar
- Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Burlington Danes Building, Du Cane Road, London, W12 0NN, UK
| | - Chris Record
- Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Burlington Danes Building, Du Cane Road, London, W12 0NN, UK
| | - David J Brooks
- Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Burlington Danes Building, Du Cane Road, London, W12 0NN, UK.,Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Institute of Neuroscience, Newcastle upon Tyne University, Newcastle upon Tyne, UK
| | - David Owen
- Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Burlington Danes Building, Du Cane Road, London, W12 0NN, UK
| | - David Sharp
- Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Burlington Danes Building, Du Cane Road, London, W12 0NN, UK
| | - Paolo A Muraro
- Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Burlington Danes Building, Du Cane Road, London, W12 0NN, UK
| | | | - Richard Nicholas
- Division of Brain Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital Campus, Burlington Danes Building, Du Cane Road, London, W12 0NN, UK
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Letter to the Editor re: Confirmation of Specific Binding of the 18-kDa Translocator Protein (TSPO) Radioligand [ 18F]GE-180: a Blocking Study Using XBD173 in Multiple Sclerosis Normal Appearing White and Grey Matter. Mol Imaging Biol 2020; 22:10-12. [PMID: 31641965 DOI: 10.1007/s11307-019-01433-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Reliable quantification of 18F-GE-180 PET neuroinflammation studies using an individually scaled population-based input function or late tissue-to-blood ratio. Eur J Nucl Med Mol Imaging 2020; 47:2887-2900. [PMID: 32322915 PMCID: PMC7651670 DOI: 10.1007/s00259-020-04810-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 04/02/2020] [Indexed: 01/23/2023]
Abstract
Purpose Tracer kinetic modeling of tissue time activity curves and the individual input function based on arterial blood sampling and metabolite correction is the gold standard for quantitative characterization of microglia activation by PET with the translocator protein (TSPO) ligand 18F-GE-180. This study tested simplified methods for quantification of 18F-GE-180 PET. Methods Dynamic 18F-GE-180 PET with arterial blood sampling and metabolite correction was performed in five healthy volunteers and 20 liver-transplanted patients. Population-based input function templates were generated by averaging individual input functions normalized to the total area under the input function using a leave-one-out approach. Individual population-based input functions were obtained by scaling the input function template with the individual parent activity concentration of 18F-GE-180 in arterial plasma in a blood sample drawn at 27.5 min or by the individual administered tracer activity, respectively. The total 18F-GE-180 distribution volume (VT) was estimated in 12 regions-of-interest (ROIs) by the invasive Logan plot using the measured or the population-based input functions. Late ROI-to-whole-blood and ROI-to-cerebellum ratio were also computed. Results Correlation with the reference VT (with individually measured input function) was very high for VT with the population-based input function scaled with the blood sample and for the ROI-to-whole-blood ratio (Pearson correlation coefficient = 0.989 ± 0.006 and 0.970 ± 0.005). The correlation was only moderate for VT with the population-based input function scaled with tracer activity dose and for the ROI-to-cerebellum ratio (0.653 ± 0.074 and 0.384 ± 0.177). Reference VT, population-based VT with scaling by the blood sample, and ROI-to-whole-blood ratio were sensitive to the TSPO gene polymorphism. Population-based VT with scaling to the administered tracer activity and the ROI-to-cerebellum ratio failed to detect a polymorphism effect. Conclusion These results support the use of a population-based input function scaled with a single blood sample or the ROI-to-whole-blood ratio at a late time point for simplified quantitative analysis of 18F-GE-180 PET. Electronic supplementary material The online version of this article (10.1007/s00259-020-04810-1) contains supplementary material, which is available to authorized users.
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Dimitrova-Shumkovska J, Krstanoski L, Veenman L. Diagnostic and Therapeutic Potential of TSPO Studies Regarding Neurodegenerative Diseases, Psychiatric Disorders, Alcohol Use Disorders, Traumatic Brain Injury, and Stroke: An Update. Cells 2020; 9:cells9040870. [PMID: 32252470 PMCID: PMC7226777 DOI: 10.3390/cells9040870] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 03/29/2020] [Accepted: 03/30/2020] [Indexed: 02/08/2023] Open
Abstract
Neuroinflammation and cell death are among the common symptoms of many central nervous system diseases and injuries. Neuroinflammation and programmed cell death of the various cell types in the brain appear to be part of these disorders, and characteristic for each cell type, including neurons and glia cells. Concerning the effects of 18-kDa translocator protein (TSPO) on glial activation, as well as being associated with neuronal cell death, as a response mechanism to oxidative stress, the changes of its expression assayed with the aid of TSPO-specific positron emission tomography (PET) tracers' uptake could also offer evidence for following the pathogenesis of these disorders. This could potentially increase the number of diagnostic tests to accurately establish the stadium and development of the disease in question. Nonetheless, the differences in results regarding TSPO PET signals of first and second generations of tracers measured in patients with neurological disorders versus healthy controls indicate that we still have to understand more regarding TSPO characteristics. Expanding on investigations regarding the neuroprotective and healing effects of TSPO ligands could also contribute to a better understanding of the therapeutic potential of TSPO activity for brain damage due to brain injury and disease. Studies so far have directed attention to the effects on neurons and glia, and processes, such as death, inflammation, and regeneration. It is definitely worthwhile to drive such studies forward. From recent research it also appears that TSPO ligands, such as PK11195, Etifoxine, Emapunil, and 2-Cl-MGV-1, demonstrate the potential of targeting TSPO for treatments of brain diseases and disorders.
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Affiliation(s)
- Jasmina Dimitrova-Shumkovska
- Department of Experimental Biochemistry, Institute of Biology, Faculty of Natural Sciences and Mathematics, University Ss Cyril and Methodius, Arhimedova 3, P.O. Box 162, 1000 Skopje, Republic of North Macedonia;
- Correspondence: (J.D.-S.); (L.V.)
| | - Ljupcho Krstanoski
- Department of Experimental Biochemistry, Institute of Biology, Faculty of Natural Sciences and Mathematics, University Ss Cyril and Methodius, Arhimedova 3, P.O. Box 162, 1000 Skopje, Republic of North Macedonia;
| | - Leo Veenman
- Technion-Israel Institute of Technology, Faculty of Medicine, Rappaport Institute of Medical Research, 1 Efron Street, P.O. Box 9697, Haifa 31096, Israel
- Correspondence: (J.D.-S.); (L.V.)
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Rawlinson C, Jenkins S, Thei L, Dallas ML, Chen R. Post-Ischaemic Immunological Response in the Brain: Targeting Microglia in Ischaemic Stroke Therapy. Brain Sci 2020; 10:brainsci10030159. [PMID: 32168831 PMCID: PMC7139954 DOI: 10.3390/brainsci10030159] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/27/2020] [Accepted: 03/07/2020] [Indexed: 12/21/2022] Open
Abstract
Microglia, the major endogenous immune cells of the central nervous system, mediate critical degenerative and regenerative responses in ischaemic stroke. Microglia become "activated", proliferating, and undergoing changes in morphology, gene and protein expression over days and weeks post-ischaemia, with deleterious and beneficial effects. Pro-inflammatory microglia (commonly referred to as M1) exacerbate secondary neuronal injury through the release of reactive oxygen species, cytokines and proteases. In contrast, microglia may facilitate neuronal recovery via tissue and vascular remodelling, through the secretion of anti-inflammatory cytokines and growth factors (a profile often termed M2). This M1/M2 nomenclature does not fully account for the microglial heterogeneity in the ischaemic brain, with some simultaneous expression of both M1 and M2 markers at the single-cell level. Understanding and regulating microglial activation status, reducing detrimental and promoting repair behaviours, present the potential for therapeutic intervention, and open a longer window of opportunity than offered by acute neuroprotective strategies. Pharmacological modulation of microglial activation status to promote anti-inflammatory gene expression can increase neurogenesis and improve functional recovery post-stroke, based on promising preclinical data. Cell-based therapies, using preconditioned microglia, are of interest as a method of therapeutic modulation of the post-ischaemic inflammatory response. Currently, there are no clinically-approved pharmacological options targeting post-ischaemic inflammation. A major developmental challenge for clinical translation will be the selective suppression of the deleterious effects of microglial activity after stroke whilst retaining (or enhancing) the neurovascular repair and remodelling responses of microglia.
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Affiliation(s)
- Charlotte Rawlinson
- School of Pharmacy and Bioengineering, Keele University, Staffordshire ST5 5BG, UK;
| | - Stuart Jenkins
- School of Medicine, Keele University, Staffordshire ST5 5BG, UK;
| | - Laura Thei
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (L.T.); (M.L.D.)
| | - Mark L. Dallas
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (L.T.); (M.L.D.)
| | - Ruoli Chen
- School of Pharmacy and Bioengineering, Keele University, Staffordshire ST5 5BG, UK;
- Correspondence: ; Tel.: +44-1782-733849; Fax: 44-1782-733326
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Zanotti-Fregonara P, Pascual B, Rostomily RC, Rizzo G, Veronese M, Masdeu JC, Turkheimer F. Anatomy of 18F-GE180, a failed radioligand for the TSPO protein. Eur J Nucl Med Mol Imaging 2020; 47:2233-2236. [DOI: 10.1007/s00259-020-04732-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 02/17/2020] [Indexed: 12/21/2022]
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Iking J, Klose J, Staniszewska M, Fendler WP, Herrmann K, Rischpler C. Imaging inflammation after myocardial infarction: implications for prognosis and therapeutic guidance. THE QUARTERLY JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING : OFFICIAL PUBLICATION OF THE ITALIAN ASSOCIATION OF NUCLEAR MEDICINE (AIMN) [AND] THE INTERNATIONAL ASSOCIATION OF RADIOPHARMACOLOGY (IAR), [AND] SECTION OF THE SOCIETY OF RADIOPHARMACEUTICAL CHEMISTRY AND BIOLOGY 2020; 64:35-50. [PMID: 32077669 DOI: 10.23736/s1824-4785.20.03232-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Inflammation after myocardial infarction (MI) has been in the focus of cardiovascular research for several years as it influences the remodeling process of the ischemic heart and thereby critically determines the clinical outcome of the patient. Today, it is well appreciated that inflammation is a crucial necessity for the initiation of the natural wound healing process; however, excessive inflammation can have detrimental effects and might result in adverse ventricular remodeling which is associated with an increased risk of heart failure. Newly emerged imaging techniques facilitate the non-invasive assessment of immune cell infiltration into the ischemic myocardium and can provide greater insight into the underlying complex and dynamic repair mechanisms. Molecular imaging of inflammation in the context of MI may help with stratification of patients at high risk of adverse ventricular remodeling post-MI which may be of diagnostic, therapeutic, and prognostic value. Novel radiopharmaceuticals may additionally provide a way to combine patient monitoring and therapy. In spite of great advances in recent years in the field of imaging sciences, clinicians still need to overcome some obstacles to a wider implementation of inflammation imaging post-MI. This review focuses on inflammation as a molecular imaging target and its potential implication in prognosis and therapeutic guidance.
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Affiliation(s)
- Janette Iking
- Department of Nuclear Medicine, University Hospital Essen, Essen, Germany.,Department of Cardiology I for Coronary and Peripheral Vascular Disease, and Heart Failure, University Hospital Münster, Münster, Germany
| | - Jasmin Klose
- Department of Nuclear Medicine, University Hospital Essen, Essen, Germany
| | | | - Wolfgang P Fendler
- Department of Nuclear Medicine, University Hospital Essen, Essen, Germany
| | - Ken Herrmann
- Department of Nuclear Medicine, University Hospital Essen, Essen, Germany
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de Groot M, Patel N, Manavaki R, Janiczek RL, Bergstrom M, Östör A, Gerlag D, Roberts A, Graves MJ, Karkera Y, Fernando D, Mistry P, Walker A, Wisniacki N, Fryer TD, Jimenez-Royo P. Quantifying disease activity in rheumatoid arthritis with the TSPO PET ligand 18F-GE-180 and comparison with 18F-FDG and DCE-MRI. EJNMMI Res 2019; 9:113. [PMID: 31858293 PMCID: PMC6923307 DOI: 10.1186/s13550-019-0576-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 11/15/2019] [Indexed: 02/14/2023] Open
Abstract
Purpose While the aetiology of rheumatoid arthritis (RA) remains unclear, many of the inflammatory components are well characterised. For diagnosis and therapy evaluation, in vivo insight into these processes would be valuable. Various imaging probes have shown value including dynamic contrast-enhanced (DCE) MRI and PET/CT using 18F-fluorodeoxyglucose (18F-FDG) or tracers targeting the translocator protein (TSPO). To evaluate 18F-GE-180, a novel TSPO PET tracer, for detecting and quantifying disease activity in RA, we compared 18F-GE-180 uptake with that of 18F-FDG and DCE-MRI measures of inflammation. Methods Eight RA patients with moderate-to-high, stable disease activity and active disease in at least one wrist were included in this study (NCT02350426). Participants underwent PET/CT examinations with 18F-GE-180 and 18F-FDG on separate visits, covering the shoulders and from the pelvis to the feet, including hands and wrists. DCE-MRI was performed on one affected hand. Uptake was compared visually between tracers as judged by an experienced radiologist and quantitatively using the maximum standardised uptake value (SUVmax). Uptake for both tracers was correlated with DCE-MRI parameters of inflammation, including the volume transfer coefficient Ktrans using Pearson correlation (r). Results PET/CT imaging with 18F-GE-180 in RA patients showed marked extra-synovial uptake around the affected joints. Overall sensitivity for detecting clinically affected joints was low (14%). 18F-GE-180 uptake did not or only weakly correlate with DCE-MRI parameters in the wrist (r = 0.09–0.31). 18F-FDG showed higher sensitivity for detecting symptomatic joints (34%), as well as strong positive correlation with DCE-MRI parameters (SUVmax vs. Ktrans: r = 0.92 for wrist; r = 0.68 for metacarpophalangeal joints). Conclusions The correlations between DCE-MRI parameters and 18F-FDG uptake support use of this PET tracer for quantification of inflammatory burden in RA. The TSPO tracer 18F-GE-180, however, has shown limited use for the investigation of RA due to its poor sensitivity and ability to quantify disease activity in RA.
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Affiliation(s)
- Marius de Groot
- Clinical Pharmacology and Experimental Medicine, GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, UK.,Department of Radiology, University of Cambridge, Cambridge, UK
| | - Neel Patel
- Clinical Pharmacology and Experimental Medicine, GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, UK
| | - Roido Manavaki
- Department of Radiology, University of Cambridge, Cambridge, UK
| | - Robert L Janiczek
- Clinical Pharmacology and Experimental Medicine, GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, UK
| | - Mats Bergstrom
- Clinical Pharmacology and Experimental Medicine, GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, UK
| | - Andrew Östör
- Monash University, Cabrini Medical Centre, Melbourne, Australia
| | | | - Alexandra Roberts
- Clinical Pharmacology and Experimental Medicine, GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, UK
| | - Martin J Graves
- Department of Radiology, University of Cambridge, Cambridge, UK
| | | | - Disala Fernando
- Clinical Unit Cambridge (CUC), GlaxoSmithKline R&D, Addenbrooke's Hospital, Cambridge, UK
| | | | - Adam Walker
- Clinical Unit Cambridge (CUC), GlaxoSmithKline R&D, Addenbrooke's Hospital, Cambridge, UK
| | - Nicolas Wisniacki
- Clinical Pharmacology and Experimental Medicine, GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, UK
| | - Tim D Fryer
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Pilar Jimenez-Royo
- Clinical Pharmacology and Experimental Medicine, GlaxoSmithKline R&D, Gunnels Wood Road, Stevenage, UK.
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Schidlitzki A, Bascuñana P, Srivastava PK, Welzel L, Twele F, Töllner K, Käufer C, Gericke B, Feleke R, Meier M, Polyak A, Ross TL, Gerhauser I, Bankstahl JP, Johnson MR, Bankstahl M, Löscher W. Proof-of-concept that network pharmacology is effective to modify development of acquired temporal lobe epilepsy. Neurobiol Dis 2019; 134:104664. [PMID: 31678583 DOI: 10.1016/j.nbd.2019.104664] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 10/08/2019] [Accepted: 10/30/2019] [Indexed: 10/25/2022] Open
Abstract
Epilepsy is a complex network phenomenon that, as yet, cannot be prevented or cured. We recently proposed network-based approaches to prevent epileptogenesis. For proof of concept we combined two drugs (levetiracetam and topiramate) for which in silico analysis of drug-protein interaction networks indicated a synergistic effect on a large functional network of epilepsy-relevant proteins. Using the intrahippocampal kainate mouse model of temporal lobe epilepsy, the drug combination was administered during the latent period before onset of spontaneous recurrent seizures (SRS). When SRS were periodically recorded by video-EEG monitoring after termination of treatment, a significant decrease in incidence and frequency of SRS was determined, indicating antiepileptogenic efficacy. Such efficacy was not observed following single drug treatment. Furthermore, a combination of levetiracetam and phenobarbital, for which in silico analysis of drug-protein interaction networks did not indicate any significant drug-drug interaction, was not effective to modify development of epilepsy. Surprisingly, the promising antiepileptogenic effect of the levetiracetam/topiramate combination was obtained in the absence of any significant neuroprotective or anti-inflammatory effects as indicated by multimodal brain imaging and histopathology. High throughput RNA-sequencing (RNA-seq) of the ipsilateral hippocampus of mice treated with the levetiracetam/topiramate combination showed that several genes that have been linked previously to epileptogenesis, were significantly differentially expressed, providing interesting entry points for future mechanistic studies. Overall, we have discovered a novel combination treatment with promise for prevention of epilepsy.
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Affiliation(s)
- Alina Schidlitzki
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany; Center for Systems Neuroscience, 30559 Hannover, Germany
| | - Pablo Bascuñana
- Department of Nuclear Medicine, Hannover Medical School, Germany
| | | | - Lisa Welzel
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany; Center for Systems Neuroscience, 30559 Hannover, Germany
| | - Friederike Twele
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Kathrin Töllner
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Christopher Käufer
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Birthe Gericke
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany; Center for Systems Neuroscience, 30559 Hannover, Germany
| | - Rahel Feleke
- Division of Brain Sciences, Imperial College London, London, UK
| | - Martin Meier
- Central Animal Facility & Institute for Laboratory Animal Science, Hannover Medical School, Hannover, Germany
| | - Andras Polyak
- Department of Nuclear Medicine, Hannover Medical School, Germany
| | - Tobias L Ross
- Department of Nuclear Medicine, Hannover Medical School, Germany
| | - Ingo Gerhauser
- Department of Pathology, University of Veterinary Medicine Hannover, Germany
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Germany
| | | | - Marion Bankstahl
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany; Center for Systems Neuroscience, 30559 Hannover, Germany; Central Animal Facility & Institute for Laboratory Animal Science, Hannover Medical School, Hannover, Germany
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, 30559 Hannover, Germany; Center for Systems Neuroscience, 30559 Hannover, Germany.
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48
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Unterrainer M, Fleischmann DF, Vettermann F, Ruf V, Kaiser L, Nelwan D, Lindner S, Brendel M, Wenter V, Stöcklein S, Herms J, Milenkovic VM, Rupprecht R, Tonn JC, Belka C, Bartenstein P, Niyazi M, Albert NL. TSPO PET, tumour grading and molecular genetics in histologically verified glioma: a correlative 18F-GE-180 PET study. Eur J Nucl Med Mol Imaging 2019; 47:1368-1380. [PMID: 31486876 DOI: 10.1007/s00259-019-04491-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 08/19/2019] [Indexed: 12/16/2022]
Abstract
BACKGROUND The 18-kDa translocator protein (TSPO) is overexpressed in brain tumours and represents an interesting target for glioma imaging. 18F-GE-180, a novel TSPO ligand, has shown improved binding affinity and a high target-to-background contrast in patients with glioblastoma. However, the association of uptake characteristics on TSPO PET using 18F-GE-180 with the histological WHO grade and molecular genetic features so far remains unknown and was evaluated in the current study. METHODS Fifty-eight patients with histologically validated glioma at initial diagnosis or recurrence were included. All patients underwent 18F-GE-180 PET, and the maximal and mean tumour-to-background ratios (TBRmax, TBRmean) as well as the PET volume were assessed. On MRI, presence/absence of contrast enhancement was evaluated. Imaging characteristics were correlated with neuropathological parameters (i.e. WHO grade, isocitrate dehydrogenase (IDH) mutation, O-6-methylguanine-DNA methyltransferase (MGMT) promoter methylation and telomerase reverse transcriptase (TERT) promoter mutation). RESULTS Six of 58 patients presented with WHO grade II, 16/58 grade III and 36/58 grade IV gliomas. An (IDH) mutation was found in 19/58 cases, and 39/58 were classified as IDH-wild type. High 18F-GE-180-uptake was observed in all but 4 cases (being WHO grade II glioma, IDH-mutant). A high association of 18F-GE-180-uptake and WHO grades was seen: WHO grade IV gliomas showed the highest uptake intensity compared with grades III and II gliomas (median TBRmax 5.15 (2.59-8.95) vs. 3.63 (1.85-7.64) vs. 1.63 (1.50-3.43), p < 0.001); this association with WHO grades persisted within the IDH-wild-type and IDH-mutant subgroup analyses (p < 0.05). Uptake intensity was also associated with the IDH mutational status with a trend towards higher 18F-GE-180-uptake in IDH-wild-type gliomas in the overall group (median TBRmax 4.67 (1.56-8.95) vs. 3.60 (1.50-7.64), p = 0.083); however, within each WHO grade, no differences were found (e.g. median TBRmax in WHO grade III glioma 4.05 (1.85-5.39) vs. 3.36 (2.32-7.64), p = 1.000). No association was found between uptake intensity and MGMT or TERT (p > 0.05 each). CONCLUSION Uptake characteristics on 18F-GE-180 PET are highly associated with the histological WHO grades, with the highest 18F-GE-180 uptake in WHO grade IV glioblastomas and a PET-positive rate of 100% among the investigated high-grade gliomas. Conversely, all TSPO-negative cases were WHO grade II gliomas. The observed association of 18F-GE-180 uptake and the IDH mutational status seems to be related to the high inter-correlation of the IDH mutational status and the WHO grades.
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Affiliation(s)
- M Unterrainer
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
- German Cancer Consortium (DKTK), Partner Site Munich, and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - D F Fleischmann
- German Cancer Consortium (DKTK), Partner Site Munich, and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
| | - F Vettermann
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - V Ruf
- Department of Neuropathology, LMU Munich, Munich, Germany
| | - L Kaiser
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - D Nelwan
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - S Lindner
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - M Brendel
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - V Wenter
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
| | - S Stöcklein
- Department of Radiology, University Hospital, LMU Munich, Munich, Germany
| | - J Herms
- Department of Neuropathology, LMU Munich, Munich, Germany
| | - V M Milenkovic
- Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany
| | - R Rupprecht
- Department of Psychiatry and Psychotherapy, University of Regensburg, Regensburg, Germany
| | - J C Tonn
- German Cancer Consortium (DKTK), Partner Site Munich, and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Neurosurgery, University Hospital, LMU Munich, Munich, Germany
| | - C Belka
- German Cancer Consortium (DKTK), Partner Site Munich, and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
| | - P Bartenstein
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany
- German Cancer Consortium (DKTK), Partner Site Munich, and German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - M Niyazi
- German Cancer Consortium (DKTK), Partner Site Munich, and German Cancer Research Center (DKFZ), Heidelberg, Germany
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
| | - N L Albert
- Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany.
- German Cancer Consortium (DKTK), Partner Site Munich, and German Cancer Research Center (DKFZ), Heidelberg, Germany.
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Myocardial Inflammation Predicts Remodeling and Neuroinflammation After Myocardial Infarction. J Am Coll Cardiol 2019; 71:263-275. [PMID: 29348018 DOI: 10.1016/j.jacc.2017.11.024] [Citation(s) in RCA: 184] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/01/2017] [Accepted: 11/06/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND The local inflammatory tissue response after acute myocardial infarction (MI) determines subsequent healing. Systemic interaction may induce neuroinflammation as a precursor to neurodegeneration. OBJECTIVES This study sought to assess the influence of MI on cardiac and brain inflammation using noninvasive positron emission tomography (PET) of the heart-brain axis. METHODS After coronary artery ligation or sham surgery, mice (n = 49) underwent serial whole-body PET imaging of the mitochondrial translocator protein (TSPO) as a marker of activated macrophages and microglia. Patients after acute MI (n = 3) were also compared to healthy controls (n = 9). RESULTS Infarct mice exhibited elevated myocardial TSPO signal at 1 week versus sham (percent injected dose per gram: 8.0 ± 1.6 vs. 4.8 ± 0.9; p < 0.001), localized to activated CD68+ inflammatory cells in the infarct. Early TSPO signal predicted subsequent left ventricular remodeling at 8 weeks (rpartial = -0.687; p = 0.001). In parallel, brain TSPO signal was elevated at 1 week (1.7 ± 0.2 vs. 1.4 ± 0.2 for sham; p = 0.017), localized to activated microglia. After interval decline at 4 weeks, progressive heart failure precipitated a second wave of neuroinflammation (1.8 ± 0.2; p = 0.005). TSPO was concurrently up-regulated in remote cardiomyocytes at 8 weeks (8.8 ± 1.7, p < 0.001) without inflammatory cell infiltration, suggesting mitochondrial impairment. Angiotensin-converting enzyme inhibitor treatment lowered acute inflammation in the heart (p = 0.003) and brain (p = 0.06) and improved late cardiac function (p = 0.05). Patients also demonstrated elevation of cardiac TSPO signal in the infarct territory, paralleled by neuroinflammation versus controls. CONCLUSIONS The brain is susceptible to acute MI and chronic heart failure. Immune activation may interconnect heart and brain dysfunction, a finding that provides a foundation for strategies to improve heart and brain outcomes.
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Recent Developments in TSPO PET Imaging as A Biomarker of Neuroinflammation in Neurodegenerative Disorders. Int J Mol Sci 2019; 20:ijms20133161. [PMID: 31261683 PMCID: PMC6650818 DOI: 10.3390/ijms20133161] [Citation(s) in RCA: 144] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 05/20/2019] [Accepted: 05/20/2019] [Indexed: 12/12/2022] Open
Abstract
Neuroinflammation is an inflammatory response in the brain and spinal cord, which can involve the activation of microglia and astrocytes. It is a common feature of many central nervous system disorders, including a range of neurodegenerative disorders. An overlap between activated microglia, pro-inflammatory cytokines and translocator protein (TSPO) ligand binding was shown in early animal studies of neurodegeneration. These findings have been translated in clinical studies, where increases in TSPO positron emission tomography (PET) signal occur in disease-relevant areas across a broad spectrum of neurodegenerative diseases. While this supports the use of TSPO PET as a biomarker to monitor response in clinical trials of novel neurodegenerative therapeutics, the clinical utility of current TSPO PET radioligands has been hampered by the lack of high affinity binding to a prevalent form of polymorphic TSPO (A147T) compared to wild type TSPO. This review details recent developments in exploration of ligand-sensitivity to A147T TSPO that have yielded ligands with improved clinical utility. In addition to developing a non-discriminating TSPO ligand, the final frontier of TSPO biomarker research requires developing an understanding of the cellular and functional interpretation of the TSPO PET signal. Recent insights resulting from single cell analysis of microglial phenotypes are reviewed.
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