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Chauveau F, Winkeler A, Chalon S, Boutin H, Becker G. PET imaging of neuroinflammation: any credible alternatives to TSPO yet? Mol Psychiatry 2024:10.1038/s41380-024-02656-9. [PMID: 38997465 DOI: 10.1038/s41380-024-02656-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 06/26/2024] [Accepted: 07/01/2024] [Indexed: 07/14/2024]
Abstract
Over the last decades, the role of neuroinflammation in neuropsychiatric conditions has attracted an exponentially growing interest. A key driver for this trend was the ability to image brain inflammation in vivo using PET radioligands targeting the Translocator Protein 18 kDa (TSPO), which is known to be expressed in activated microglia and astrocytes upon inflammatory events as well as constitutively in endothelial cells. TSPO is a mitochondrial protein that is expressed mostly by microglial cells upon activation but is also expressed by astrocytes in some conditions and constitutively by endothelial cells. Therefore, our current understanding of neuroinflammation dynamics is hampered by the lack of alternative targets available for PET imaging. We performed a systematic search and review on radiotracers developed for neuroinflammation PET imaging apart from TSPO. The following targets of interest were identified through literature screening (including previous narrative reviews): P2Y12R, P2X7R, CSF1R, COX (microglial targets), MAO-B, I2BS (astrocytic targets), CB2R & S1PRs (not specific of a single cell type). We determined the level of development and provided a scoping review for each target. Strikingly, astrocytic biomarker MAO-B has progressed in clinical investigations the furthest, while few radiotracers (notably targeting S1P1Rs, CSF1R) are being implemented in clinical investigations. Other targets such as CB2R and P2X7R have proven disappointing in clinical studies (e.g. poor signal, lack of changes in disease conditions, etc.). While astrocytic targets are promising, development of new biomarkers and tracers specific for microglial activation has proven challenging.
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Affiliation(s)
- Fabien Chauveau
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
| | - Alexandra Winkeler
- Université Paris-Saclay, Inserm, CNRS, CEA, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401, Orsay, France
| | - Sylvie Chalon
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France
| | - Hervé Boutin
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France.
| | - Guillaume Becker
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
- Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail, 14 rue Pierre et Marie Curie, 94701, Maisons-Alfort, Cedex, France
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2
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Lee N, Choi JY, Ryu YH. The development status of PET radiotracers for evaluating neuroinflammation. Nucl Med Mol Imaging 2024; 58:160-176. [PMID: 38932754 PMCID: PMC11196502 DOI: 10.1007/s13139-023-00831-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/16/2023] [Accepted: 12/05/2023] [Indexed: 06/28/2024] Open
Abstract
Neuroinflammation is associated with the pathophysiologies of neurodegenerative and psychiatric disorders. Evaluating neuroinflammation using positron emission tomography (PET) plays an important role in the early diagnosis and determination of proper treatment of brain diseases. To quantify neuroinflammatory responses in vivo, many PET tracers have been developed using translocator proteins, imidazole-2 binding site, cyclooxygenase, monoamine oxidase-B, adenosine, cannabinoid, purinergic P2X7, and CSF-1 receptors as biomarkers. In this review, we introduce the latest developments in PET tracers that can image neuroinflammation, focusing on clinical trials, and further consider their current implications.
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Affiliation(s)
- Namhun Lee
- Division of Applied RI, Korea Institute of Radiological & Medical Sciences, 75 Nowon-ro, Nowon-gu, Seoul, 01812 Korea
| | - Jae Yong Choi
- Division of Applied RI, Korea Institute of Radiological & Medical Sciences, 75 Nowon-ro, Nowon-gu, Seoul, 01812 Korea
- Radiological and Medico-Oncological Sciences, University of Science and Technology (UST), Seoul, Korea
| | - Young Hoon Ryu
- Department of Nuclear Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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3
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Emvalomenos GM, Kang JWM, Jupp B, Mychasiuk R, Keay KA, Henderson LA. Recent developments and challenges in positron emission tomography imaging of gliosis in chronic neuropathic pain. Pain 2024:00006396-990000000-00597. [PMID: 38713812 DOI: 10.1097/j.pain.0000000000003247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 03/05/2024] [Indexed: 05/09/2024]
Abstract
ABSTRACT Understanding the mechanisms that underpin the transition from acute to chronic pain is critical for the development of more effective and targeted treatments. There is growing interest in the contribution of glial cells to this process, with cross-sectional preclinical studies demonstrating specific changes in these cell types capturing targeted timepoints from the acute phase and the chronic phase. In vivo longitudinal assessment of the development and evolution of these changes in experimental animals and humans has presented a significant challenge. Recent technological advances in preclinical and clinical positron emission tomography, including the development of specific radiotracers for gliosis, offer great promise for the field. These advances now permit tracking of glial changes over time and provide the ability to relate these changes to pain-relevant symptomology, comorbid psychiatric conditions, and treatment outcomes at both a group and an individual level. In this article, we summarize evidence for gliosis in the transition from acute to chronic pain and provide an overview of the specific radiotracers available to measure this process, highlighting their potential, particularly when combined with ex vivo/in vitro techniques, to understand the pathophysiology of chronic neuropathic pain. These complementary investigations can be used to bridge the existing gap in the field concerning the contribution of gliosis to neuropathic pain and identify potential targets for interventions.
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Affiliation(s)
- Gaelle M Emvalomenos
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | - James W M Kang
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | - Bianca Jupp
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Australia
| | - Kevin A Keay
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
| | - Luke A Henderson
- School of Medical Sciences [Neuroscience], and the Brain and Mind Centre, The University of Sydney, Sydney, Australia
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4
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Martynov A, Farber B, Bomko T, Beckles DL, Kleyn I. Molecular Modeling, Synthesis, and Antihyperglycemic Activity of the New Benzimidazole Derivatives - Imidazoline Receptor Agonists. Drug Des Devel Ther 2024; 18:1035-1052. [PMID: 38585255 PMCID: PMC10999201 DOI: 10.2147/dddt.s447289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 02/28/2024] [Indexed: 04/09/2024] Open
Abstract
Introduction The paper presents the results of a study on the first synthesized benzimidazole derivatives obtained from labile nature carboxylic acids. The synthesis conditions of these substances were studied, their structure was proved, and some components were found to have sugar-reducing activity on the model of alloxan diabetes in rats. Methods The study used molecular modeling methods such as docking based on the evolutionary model (igemdock), RP_HPLC method to monitor the synthesis reaction, and 1H NMR and 13C NMR, and other methods of organic chemistry to confirm the structures of synthesized substances. Results & Discussion The docking showed that the ursodeoxycholic acid benzimidazole derivatives have high tropics to all imidazoline receptor carriers (PDB ID: 2XCG, 2bk3, 3p0c, 1QH4). The ursodeoxycholic acid benzimidazole derivative and arginine and histidine benzimidazole derivatives showed the highest sugar-lowering activity in the experiment on alloxan-diabetic rats. For these derivatives, the difference in glucose levels of treated rats was significant against untreated control. Therefore, the new derivatives of benzimidazole and labile natural organic acids can be used to create new classes of imidazoline receptor inhibitors for the treatment of diabetes mellitus and hypertension.
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Affiliation(s)
- Artur Martynov
- Laboratory and Clinical department of Molecular Immunopharmacology, SI “ I. Mechnikov Institute of Microbiology and Immunology of National Academy of Medical Sciences of Ukraine, Kharkiv, Ukraine
| | | | - Tatyana Bomko
- Laboratory and Clinical department of Molecular Immunopharmacology, SI “ I. Mechnikov Institute of Microbiology and Immunology of National Academy of Medical Sciences of Ukraine, Kharkiv, Ukraine
| | | | - Ilya Kleyn
- SUNY Downstate Medical Center / University Hospital of Brooklyn, New York, NY, USA
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5
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Parker CA, Nutt DJ, Tyacke RJ. Imidazoline-I2 PET Tracers in Neuroimaging. Int J Mol Sci 2023; 24:9787. [PMID: 37372936 DOI: 10.3390/ijms24129787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/24/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023] Open
Abstract
Targeting neuroinflammation, and in particular, microglial activation and astrocytosis, is a current area of the focus of new treatment interventions for a number of neurodegenerative disorders. Probing the roles of microglia and astrocytes in human disease requires the development of useful tools, such as PET imaging tools that are specific for the cell type(s) of interest. This review concentrates on the recent advances in the development of Imidazoline2 binding site (I2BS) PET tracers, which are purported to target astrocytes, and hence could represent key clinical imaging tools for targeting astrocytes in neurodegenerative disease. Five PET tracers for the I2BS are described in this review, with only one (11C-BU99008) being currently validated to GMP for clinical use, and data reported from healthy volunteers, Alzheimer's disease patients, and Parkinson's disease patients. The clinical data utilising 11C-BU99008 have revealed the potential early involvement of astrogliosis in neurodegeneration that might precede the activation of microglia, which, if confirmed, could provide a vital new means for potentially targeting neurodegeneration earlier in the disease course.
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Affiliation(s)
- Christine A Parker
- Neuropsychopharmacology Unit, Division of Psychiatry, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
- GlaxoSmithKline, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - David J Nutt
- Neuropsychopharmacology Unit, Division of Psychiatry, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
| | - Robin J Tyacke
- Neuropsychopharmacology Unit, Division of Psychiatry, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
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Singh P, Singh D, Srivastava P, Mishra G, Tiwari AK. Evaluation of advanced, pathophysiologic new targets for imaging of CNS. Drug Dev Res 2023; 84:484-513. [PMID: 36779375 DOI: 10.1002/ddr.22040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 12/12/2022] [Accepted: 12/31/2022] [Indexed: 02/14/2023]
Abstract
The inadequate information about the in vivo pathological, physiological, and neurological impairments, as well as the absence of in vivo tools for assessing brain penetrance and the efficiency of newly designed drugs, has hampered the development of new techniques for the treatment for variety of new central nervous system (CNS) diseases. The searching sites such as Science Direct and PubMed were used to find out the numerous distinct tracers across 16 CNS targets including tau, synaptic vesicle glycoprotein, the adenosine 2A receptor, the phosphodiesterase enzyme PDE10A, and the purinoceptor, among others. Among the most encouraging are [18 F]FIMX for mGluR imaging, [11 C]Martinostat for Histone deacetylase, [18 F]MNI-444 for adenosine 2A imaging, [11 C]ER176 for translocator protein, and [18 F]MK-6240 for tau imaging. We also reviewed the findings for each tracer's features and potential for application in CNS pathophysiology and therapeutic evaluation investigations, including target specificity, binding efficacy, and pharmacokinetic factors. This review aims to present a current evaluation of modern positron emission tomography tracers for CNS targets, with a focus on recent advances for targets that have newly emerged for imaging in humans.
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Affiliation(s)
- Priya Singh
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Deepika Singh
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Pooja Srivastava
- Division of Cyclotron and Radiopharmaceuticals Sciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Gauri Mishra
- Department of Zoology, Swami Shraddhananad College, University of Delhi, Alipur, Delhi, India
| | - Anjani K Tiwari
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
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7
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Kumar A, Fontana IC, Nordberg A. Reactive astrogliosis: A friend or foe in the pathogenesis of Alzheimer's disease. J Neurochem 2023; 164:309-324. [PMID: 34931315 DOI: 10.1111/jnc.15565] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 11/28/2022]
Abstract
Astrocytes are highly efficient homeostatic glial cells playing a crucial role in optimal brain functioning and homeostasis. Astrocytes respond to changes in brain homoeostasis following central nervous system (CNS) injury/diseased state by a specific defence mechanism called reactive astrogliosis. Recent studies have implicated and placed reactive astrogliosis in the centre of pathophysiology of Alzheimer's disease (AD) and other neurodegenerative disorders. The AD biomarker field is evolving rapidly with new findings providing strong evidence which supports the notion that a reactive astrogliosis is an early event in the time course of AD progression which may precede other pathological hallmarks of AD. Clinical/translational in vivo PET and in vitro postmortem brain imaging studies demonstrated 'a first and second wave' of reactive astrogliosis in AD with distinct close-loop relationships with other pathological biomarkers at different stages of the disease. At the end stages, reactive astrocytes are found to be associated, or in proximity, with amyloid plaque and tau pathological deposits in postmortem AD brains. Several new PET-tracers, which are being in pipeline and validated at a very fast pace for mapping and visualising reactive astrogliosis in the brain, will provide further invaluable mechanistic insights into AD and other non-AD dementia pathologies. The complementary roles of microglia and astrocyte activation in AD progression, along with the clinical value of new fluid astrocytes biomarkers in the context of existing biomarkers, are the latest avenue that needs further exploration.
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Affiliation(s)
- Amit Kumar
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Igor C Fontana
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Agneta Nordberg
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.,Theme Aging, Karolinska University Hospital, Stockholm, Sweden
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8
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Huang J. Novel brain PET imaging agents: Strategies for imaging neuroinflammation in Alzheimer’s disease and mild cognitive impairment. Front Immunol 2022; 13:1010946. [PMID: 36211392 PMCID: PMC9537554 DOI: 10.3389/fimmu.2022.1010946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 09/06/2022] [Indexed: 11/25/2022] Open
Abstract
Alzheimer’s disease (AD) is a devastating neurodegenerative disease with a concealed onset and continuous deterioration. Mild cognitive impairment (MCI) is the prodromal stage of AD. Molecule-based imaging with positron emission tomography (PET) is critical in tracking pathophysiological changes among AD and MCI patients. PET with novel targets is a promising approach for diagnostic imaging, particularly in AD patients. Our present review overviews the current status and applications of in vivo molecular imaging toward neuroinflammation. Although radiotracers can remarkably diagnose AD and MCI patients, a variety of limitations prevent the recommendation of a single technique. Recent studies examining neuroinflammation PET imaging suggest an alternative approach to evaluate disease progression. This review concludes that PET imaging towards neuroinflammation is considered a promising approach to deciphering the enigma of the pathophysiological process of AD and MCI.
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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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10
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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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Relationship between astrocyte reactivity, using novel 11C-BU99008 PET, and glucose metabolism, grey matter volume and amyloid load in cognitively impaired individuals. Mol Psychiatry 2022; 27:2019-2029. [PMID: 35125495 PMCID: PMC9126819 DOI: 10.1038/s41380-021-01429-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 12/10/2021] [Accepted: 12/23/2021] [Indexed: 12/01/2022]
Abstract
Post mortem neuropathology suggests that astrocyte reactivity may play a significant role in neurodegeneration in Alzheimer's disease. We explored this in vivo using multimodal PET and MRI imaging. Twenty subjects (11 older, cognitively impaired patients and 9 age-matched healthy controls) underwent brain scanning using the novel reactive astrocyte PET tracer 11C-BU99008, 18F-FDG and 18F-florbetaben PET, and T1-weighted MRI. Differences between cognitively impaired patients and healthy controls in regional and voxel-wise levels of astrocyte reactivity, glucose metabolism, grey matter volume and amyloid load were explored, and their relationship to each other was assessed using Biological Parametric Mapping (BPM). Amyloid beta (Aβ)-positive patients showed greater 11C-BU99008 uptake compared to controls, except in the temporal lobe, whilst further increased 11C-BU99008 uptake was observed in Mild Cognitive Impairment subjects compared to those with Alzheimer's disease in the frontal, temporal and cingulate cortices. BPM correlations revealed that regions which showed reduced 11C-BU99008 uptake in Aβ-positive patients compared to controls, such as the temporal lobe, also showed reduced 18F-FDG uptake and grey matter volume, although the correlations with 18F-FDG uptake were not replicated in the ROI analysis. BPM analysis also revealed a regionally-dynamic relationship between astrocyte reactivity and amyloid uptake: increased amyloid load in cortical association areas of the temporal lobe and cingulate cortices was associated with reduced 11C-BU99008 uptake, whilst increased amyloid uptake in primary motor and sensory areas (in which amyloid deposition occurs later) was associated with increased 11C-BU99008 uptake. These novel observations add to the hypothesis that while astrocyte reactivity may be triggered by early Aβ-deposition, sustained pro-inflammatory astrocyte reactivity with greater amyloid deposition may lead to astrocyte dystrophy and amyloid-associated neuropathology such as grey matter atrophy and glucose hypometabolism, although the evidence for glucose hypometabolism here is less strong.
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12
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Brumberg J, Varrone A. New PET radiopharmaceuticals for imaging CNS diseases. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00002-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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13
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Liu Y, Jiang H, Qin X, Tian M, Zhang H. PET imaging of reactive astrocytes in neurological disorders. Eur J Nucl Med Mol Imaging 2021; 49:1275-1287. [PMID: 34873637 PMCID: PMC8921128 DOI: 10.1007/s00259-021-05640-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 11/24/2021] [Indexed: 12/17/2022]
Abstract
The reactive astrocytes manifest molecular, structural, and functional remodeling in injury, infection, or diseases of the CNS, which play a critical role in the pathological mechanism of neurological diseases. A growing need exists for dependable approach to better characterize the activation of astrocyte in vivo. As an advanced molecular imaging technology, positron emission tomography (PET) has the potential for visualizing biological activities at the cellular levels. In the review, we summarized the PET visualization strategies for reactive astrocytes and discussed the applications of astrocyte PET imaging in neurological diseases. Future studies are needed to pay more attention to the development of specific imaging agents for astrocytes and further improve our exploration of reactive astrocytes in various diseases.
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Affiliation(s)
- Yu Liu
- Department of Nuclear Medicine and PET Center, The Second Affiliated Hospital of Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, Zhejiang, China.,Institute of Nuclear Medicine and Molecular Imaging of Zhejiang University, Hangzhou, China.,Key Laboratory of Medical Molecular Imaging of Zhejiang Province, Hangzhou, China
| | - Han Jiang
- PET-CT Center, Fujian Medical University Union Hospital, Fuzhou, 350001, China
| | - Xiyi Qin
- Department of Nuclear Medicine and PET Center, The Second Affiliated Hospital of Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, Zhejiang, China.,Institute of Nuclear Medicine and Molecular Imaging of Zhejiang University, Hangzhou, China.,Key Laboratory of Medical Molecular Imaging of Zhejiang Province, Hangzhou, China
| | - Mei Tian
- Department of Nuclear Medicine and PET Center, The Second Affiliated Hospital of Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, Zhejiang, China. .,Institute of Nuclear Medicine and Molecular Imaging of Zhejiang University, Hangzhou, China. .,Key Laboratory of Medical Molecular Imaging of Zhejiang Province, Hangzhou, China.
| | - Hong Zhang
- Department of Nuclear Medicine and PET Center, The Second Affiliated Hospital of Zhejiang University School of Medicine, 88 Jiefang Road, Hangzhou, 310009, Zhejiang, China. .,Institute of Nuclear Medicine and Molecular Imaging of Zhejiang University, Hangzhou, China. .,Key Laboratory of Medical Molecular Imaging of Zhejiang Province, Hangzhou, China. .,College of Biomedical Engineering & Instrument Science, Zhejiang University, Hangzhou, China. .,Key Laboratory for Biomedical Engineering of Ministry of Education, Zhejiang University, Hangzhou, China.
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14
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Calsolaro V, Matthews PM, Donat CK, Livingston NR, Femminella GD, Guedes SS, Myers J, Fan Z, Tyacke RJ, Venkataraman AV, Perneczky R, Gunn R, Rabiner EA, Gentleman S, Parker CA, Murphy PS, Wren PB, Hinz R, Sastre M, Nutt DJ, Edison P. Astrocyte reactivity with late-onset cognitive impairment assessed in vivo using 11C-BU99008 PET and its relationship with amyloid load. Mol Psychiatry 2021; 26:5848-5855. [PMID: 34267329 PMCID: PMC8758500 DOI: 10.1038/s41380-021-01193-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 05/16/2021] [Accepted: 06/08/2021] [Indexed: 02/06/2023]
Abstract
11C-BU99008 is a novel positron emission tomography (PET) tracer that enables selective imaging of astrocyte reactivity in vivo. To explore astrocyte reactivity associated with Alzheimer's disease, 11 older, cognitively impaired (CI) subjects and 9 age-matched healthy controls (HC) underwent 3T magnetic resonance imaging (MRI), 18F-florbetaben and 11C-BU99008 PET. The 8 amyloid (Aβ)-positive CI subjects had higher 11C-BU99008 uptake relative to HC across the whole brain, but particularly in frontal, temporal, medial temporal and occipital lobes. Biological parametric mapping demonstrated a positive voxel-wise neuroanatomical correlation between 11C-BU99008 and 18F-florbetaben. Autoradiography using 3H-BU99008 with post-mortem Alzheimer's brains confirmed through visual assessment that increased 3H-BU99008 binding localised with the astrocyte protein glial fibrillary acid protein and was not displaced by PiB or florbetaben. This proof-of-concept study provides direct evidence that 11C-BU99008 can measure in vivo astrocyte reactivity in people with late-life cognitive impairment and Alzheimer's disease. Our results confirm that increased astrocyte reactivity is found particularly in cortical regions with high Aβ load. Future studies now can explore how clinical expression of disease varies with astrocyte reactivity.
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Affiliation(s)
| | - Paul M Matthews
- Department of Brain Sciences, Imperial College London, London, UK
- UK Dementia Research Institute, Imperial College London, London, UK
| | - Cornelius K Donat
- Department of Brain Sciences, Imperial College London, London, UK
- Centre for Blast Injury Studies, Imperial College London, London, UK
| | | | | | | | - Jim Myers
- Department of Brain Sciences, Imperial College London, London, UK
| | - Zhen Fan
- Department of Brain Sciences, Imperial College London, London, UK
| | - Robin J Tyacke
- Department of Brain Sciences, Imperial College London, London, UK
| | | | - Robert Perneczky
- Department of Psychiatry and Psychotherapy, University Hospital, LMU Munich, Munich, Germany
- German Centre for Neurodegenerative Disorders (DZNE), Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), Munich, Germany
- Ageing Epidemiology Research Unit (AGE), School of Public Health, Imperial College London, London, UK
| | - Roger Gunn
- Department of Brain Sciences, Imperial College London, London, UK
- Invicro, London, UK
| | | | - Steve Gentleman
- Department of Brain Sciences, Imperial College London, London, UK
| | - Christine A Parker
- Department of Brain Sciences, Imperial College London, London, UK
- GlaxoSmithKline, Stevenage, UK
| | | | | | - Rainer Hinz
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester, UK
| | - Magdalena Sastre
- Department of Brain Sciences, Imperial College London, London, UK
| | - David J Nutt
- Department of Brain Sciences, Imperial College London, London, UK
| | - Paul Edison
- Department of Brain Sciences, Imperial College London, London, UK.
- Cardiff University, Cardiff, Wales, United Kingdom.
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15
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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: 46] [Impact Index Per Article: 15.3] [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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16
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Goud NS, Bhattacharya A, Joshi RK, Nagaraj C, Bharath RD, Kumar P. Carbon-11: Radiochemistry and Target-Based PET Molecular Imaging Applications in Oncology, Cardiology, and Neurology. J Med Chem 2021; 64:1223-1259. [PMID: 33499603 DOI: 10.1021/acs.jmedchem.0c01053] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The positron emission tomography (PET) molecular imaging technique has gained its universal value as a remarkable tool for medical diagnosis and biomedical research. Carbon-11 is one of the promising radiotracers that can report target-specific information related to its pharmacology and physiology to understand the disease status. Currently, many of the available carbon-11 (t1/2 = 20.4 min) PET radiotracers are heterocyclic derivatives that have been synthesized using carbon-11 inserted different functional groups obtained from primary and secondary carbon-11 precursors. A spectrum of carbon-11 PET radiotracers has been developed against many of the upregulated and emerging targets for the diagnosis, prognosis, prediction, and therapy in the fields of oncology, cardiology, and neurology. This review focuses on the carbon-11 radiochemistry and various target-specific PET molecular imaging agents used in tumor, heart, brain, and neuroinflammatory disease imaging along with its associated pathology.
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Affiliation(s)
- Nerella Sridhar Goud
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Ahana Bhattacharya
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Raman Kumar Joshi
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Chandana Nagaraj
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Rose Dawn Bharath
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
| | - Pardeep Kumar
- Department of Neuroimaging and Interventional Radiology (NIIR), National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru 560 029, India
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17
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Astroglial tracer BU99008 detects multiple binding sites in Alzheimer's disease brain. Mol Psychiatry 2021; 26:5833-5847. [PMID: 33888872 PMCID: PMC8758481 DOI: 10.1038/s41380-021-01101-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/17/2021] [Accepted: 04/01/2021] [Indexed: 12/15/2022]
Abstract
With reactive astrogliosis being established as one of the hallmarks of Alzheimer's disease (AD), there is high interest in developing novel positron emission tomography (PET) tracers to detect early astrocyte reactivity. BU99008, a novel astrocytic PET ligand targeting imidazoline-2 binding sites (I2BS) on astrocytes, might be a suitable candidate. Here we demonstrate for the first time that BU99008 could visualise reactive astrogliosis in postmortem AD brains and propose a multiple binding site [Super-high-affinity (SH), High-affinity (HA) and Low-affinity (LA)] model for BU99008, I2BS specific ligands (2-BFI and BU224) and deprenyl in AD and control (CN) brains. The proportion (%) and affinities of these sites varied significantly between the BU99008, 2-BFI, BU224 and deprenyl in AD and CN brains. Regional binding studies demonstrated significantly higher 3H-BU99008 binding in AD brain regions compared to CN. Comparative autoradiography studies reinforced these findings, showing higher specific binding for 3H-BU99008 than 3H-Deprenyl in sporadic AD brain compared to CN, implying that they might have different targets. The data clearly shows that BU99008 could detect I2BS expressing reactive astrocytes with good selectivity and specificity and hence be a potential attractive clinical astrocytic PET tracer for gaining further insight into the role of reactive astrogliosis in AD.
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18
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Bousquet P, Hudson A, García-Sevilla JA, Li JX. Imidazoline Receptor System: The Past, the Present, and the Future. Pharmacol Rev 2020; 72:50-79. [PMID: 31819014 DOI: 10.1124/pr.118.016311] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Imidazoline receptors historically referred to a family of nonadrenergic binding sites that recognize compounds with an imidazoline moiety, although this has proven to be an oversimplification. For example, none of the proposed endogenous ligands for imidazoline receptors contain an imidazoline moiety but they are diverse in their chemical structure. Three receptor subtypes (I1, I2, and I3) have been proposed and the understanding of each has seen differing progress over the decades. I1 receptors partially mediate the central hypotensive effects of clonidine-like drugs. Moxonidine and rilmenidine have better therapeutic profiles (fewer side effects) than clonidine as antihypertensive drugs, thought to be due to their higher I1/α 2-adrenoceptor selectivity. Newer I1 receptor agonists such as LNP599 [3-chloro-2-methyl-phenyl)-(4-methyl-4,5-dihydro-3H-pyrrol-2-yl)-amine hydrochloride] have little to no activity on α 2-adrenoceptors and demonstrate promising therapeutic potential for hypertension and metabolic syndrome. I2 receptors associate with several distinct proteins, but the identities of these proteins remain elusive. I2 receptor agonists have demonstrated various centrally mediated effects including antinociception and neuroprotection. A new I2 receptor agonist, CR4056 [2-phenyl-6-(1H-imidazol-1yl) quinazoline], demonstrated clear analgesic activity in a recently completed phase II clinical trial and holds great promise as a novel I2 receptor-based first-in-class nonopioid analgesic. The understanding of I3 receptors is relatively limited. Existing data suggest that I3 receptors may represent a binding site at the Kir6.2-subtype ATP-sensitive potassium channels in pancreatic β-cells and may be involved in insulin secretion. Despite the elusive nature of their molecular identities, recent progress on drug discovery targeting imidazoline receptors (I1 and I2) demonstrates the exciting potential of these compounds to elicit neuroprotection and to treat various disorders such as hypertension, metabolic syndrome, and chronic pain.
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Affiliation(s)
- Pascal Bousquet
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
| | - Alan Hudson
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
| | - Jesús A García-Sevilla
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
| | - Jun-Xu Li
- Faculty of Medicine, University of Strasbourg, Strasbourg, France (P.B.); Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada (A.H.); Laboratory of Neuropharmacology, University Research Institute on Health Sciences, University of the Balearic Islands, Palma de Malllorca, Spain (J.A.G.-S.); and Department of Pharmacology and Toxicology, University at Buffalo, Buffalo, New York (J.-X.L.)
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19
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McCluskey SP, Plisson C, Rabiner EA, Howes O. Advances in CNS PET: the state-of-the-art for new imaging targets for pathophysiology and drug development. Eur J Nucl Med Mol Imaging 2020; 47:451-489. [PMID: 31541283 PMCID: PMC6974496 DOI: 10.1007/s00259-019-04488-0] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Accepted: 08/15/2019] [Indexed: 02/07/2023]
Abstract
PURPOSE A limit on developing new treatments for a number of central nervous system (CNS) disorders has been the inadequate understanding of the in vivo pathophysiology underlying neurological and psychiatric disorders and the lack of in vivo tools to determine brain penetrance, target engagement, and relevant molecular activity of novel drugs. Molecular neuroimaging provides the tools to address this. This article aims to provide a state-of-the-art review of new PET tracers for CNS targets, focusing on developments in the last 5 years for targets recently available for in-human imaging. METHODS We provide an overview of the criteria used to evaluate PET tracers. We then used the National Institute of Mental Health Research Priorities list to identify the key CNS targets. We conducted a PubMed search (search period 1st of January 2013 to 31st of December 2018), which yielded 40 new PET tracers across 16 CNS targets which met our selectivity criteria. For each tracer, we summarised the evidence of its properties and potential for use in studies of CNS pathophysiology and drug evaluation, including its target selectivity and affinity, inter and intra-subject variability, and pharmacokinetic parameters. We also consider its potential limitations and missing characterisation data, but not specific applications in drug development. Where multiple tracers were present for a target, we provide a comparison of their properties. RESULTS AND CONCLUSIONS Our review shows that multiple new tracers have been developed for proteinopathy targets, particularly tau, as well as the purinoceptor P2X7, phosphodiesterase enzyme PDE10A, and synaptic vesicle glycoprotein 2A (SV2A), amongst others. Some of the most promising of these include 18F-MK-6240 for tau imaging, 11C-UCB-J for imaging SV2A, 11C-CURB and 11C-MK-3168 for characterisation of fatty acid amide hydrolase, 18F-FIMX for metabotropic glutamate receptor 1, and 18F-MNI-444 for imaging adenosine 2A. Our review also identifies recurrent issues within the field. Many of the tracers discussed lack in vivo blocking data, reducing confidence in selectivity. Additionally, late-stage identification of substantial off-target sites for multiple tracers highlights incomplete pre-clinical characterisation prior to translation, as well as human disease state studies carried out without confirmation of test-retest reproducibility.
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Affiliation(s)
- Stuart P McCluskey
- Invicro LLC, A Konica Minolta Company, Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK.
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital, London, UK.
| | - Christophe Plisson
- Invicro LLC, A Konica Minolta Company, Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Eugenii A Rabiner
- Invicro LLC, A Konica Minolta Company, Burlington Danes Building, Imperial College London, Hammersmith Hospital, Du Cane Road, London, W12 0NN, UK
| | - Oliver Howes
- Psychiatric Imaging Group, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital, London, UK
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20
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Wilson H, Dervenoulas G, Pagano G, Tyacke RJ, Polychronis S, Myers J, Gunn RN, Rabiner EA, Nutt D, Politis M. Imidazoline 2 binding sites reflecting astroglia pathology in Parkinson's disease: an in vivo11C-BU99008 PET study. Brain 2019; 142:3116-3128. [PMID: 31504212 DOI: 10.1093/brain/awz260] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 06/06/2019] [Accepted: 07/04/2019] [Indexed: 12/11/2022] Open
Abstract
Astroglia are multifunctional cells that regulate neuroinflammation and maintain homeostasis within the brain. Astroglial α-synuclein-positive cytoplasmic accumulations have been shown post-mortem in patients with Parkinson's disease and therefore astroglia may play an important role in the initiation and progression of Parkinson's disease. Imidazoline 2 binding sites are expressed on activated astroglia in the cortex, hippocampus, basal ganglia and brainstem; therefore, by measuring imidazoline 2 binding site levels we can indirectly evaluate astrogliosis in patients with Parkinson's disease. Here, we aimed to evaluate the role of astroglia activation in vivo in patients with Parkinson's disease using 11C-BU99008 PET, a novel radioligand with high specificity and selectivity for imidazoline 2 binding sites. Twenty-two patients with Parkinson's disease and 14 healthy control subjects underwent 3 T MRI and a 120-min 11C-BU99008 PET scan with volume of distribution (VT) estimated using a two-tissue compartmental model with a metabolite corrected arterial plasma input function. Parkinson's disease patients were stratified into early (n = 8) and moderate/advanced (n = 14) groups according to disease stage. In early Parkinson's disease, increased 11C-BU99008 VT uptake was observed in frontal (P = 0.022), temporal (P = 0.02), parietal (P = 0.026) and occipital (P = 0.047) cortical regions compared with healthy controls. The greatest 11C-BU99008 VT increase in patients with early Parkinson's disease was observed in the brainstem (52%; P = 0.018). In patients with moderate/advanced Parkinson's disease, loss of 11C-BU99008 VT was observed across frontal (P = 0.002), temporal (P < 0.001), parietal (P = 0.039), occipital (P = 0.024), and insula (P < 0.001) cortices; and in the subcortical regions of caudate (P < 0.001), putamen (P < 0.001) and thalamus (P < 0.001); and in the brainstem (P = 0.018) compared with healthy controls. In patients with Parkinson's disease, loss of 11C-BU99008 VT in cortical regions, striatum, thalamus and brainstem correlated with longer disease duration (P < 0.05) and higher disease burden scores, measured with Movement Disorder Society Unified Parkinson's Disease Rating Scale (P < 0.05). In the subgroup of patients with moderate/advanced Parkinson's disease, loss of 11C-BU99008 VT in the frontal (r = 0.79; P = 0.001), temporal (r = 0.74; P = 0.002) and parietal (r = 0.89; P < 0.001) cortex correlated with global cognitive impairment. This study demonstrates in vivo the role of astroglia in the initiation and progression of Parkinson's disease. Reactive astroglia observed early in Parkinson's disease could reflect a neuroprotective compensatory mechanisms and pro-inflammatory upregulation in response to α-synuclein accumulation. However, as the disease progresses and significant neurodegeneration occurs, astroglia lose their reactive function and such loss in the cortex has clinical relevance in the development of cognitive impairment.
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Affiliation(s)
- Heather Wilson
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - George Dervenoulas
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Gennaro Pagano
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Robin J Tyacke
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, UK
| | - Sotirios Polychronis
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Jim Myers
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, UK
| | - Roger N Gunn
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
- Invicro LLC, Centre for Imaging Sciences, Hammersmith Hospital, London, UK
| | - Eugenii A Rabiner
- Invicro LLC, Centre for Imaging Sciences, Hammersmith Hospital, London, UK
- Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - David Nutt
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, UK
| | - Marios Politis
- Neurodegeneration Imaging Group, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
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21
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Prospects and challenges of imaging neuroinflammation beyond TSPO in Alzheimer's disease. Eur J Nucl Med Mol Imaging 2019; 46:2831-2847. [PMID: 31396666 PMCID: PMC6879435 DOI: 10.1007/s00259-019-04462-w] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 07/24/2019] [Indexed: 02/06/2023]
Abstract
Neuroinflammation, as defined by the activation of microglia and astrocytes, has emerged in the last years as a key element of the pathogenesis of neurodegenerative diseases based on genetic findings and preclinical and human studies. This has raised the need for new methodologies to assess and follow glial activation in patients, prompting the development of PET ligands for molecular imaging of glial cells and novel structural MRI and DTI tools leading to a multimodal approach. The present review describes the recent advancements in microglia and astrocyte biology in the context of health, ageing, and Alzheimer's disease, the most common dementia worldwide. The review further delves in molecular imaging discussing the challenges associated with past and present targets, including conflicting findings, and finally, presenting novel methodologies currently explored to improve our in vivo knowledge of the neuroinflammatory patterns in Alzheimer's disease. With glial cell activation as a potential therapeutic target in neurodegenerative diseases, the translational research between cell biologists, chemists, physicists, radiologists, and neurologists should be strengthened.
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22
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Perani D, Iaccarino L, Lammertsma AA, Windhorst AD, Edison P, Boellaard R, Hansson O, Nordberg A, Jacobs AH. A new perspective for advanced positron emission tomography-based molecular imaging in neurodegenerative proteinopathies. Alzheimers Dement 2019; 15:1081-1103. [PMID: 31230910 DOI: 10.1016/j.jalz.2019.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/21/2019] [Accepted: 02/20/2019] [Indexed: 12/12/2022]
Abstract
Recent studies in neurodegenerative conditions have increasingly highlighted that the same neuropathology can trigger different clinical phenotypes or, vice-versa, that similar phenotypes can be triggered by different neuropathologies. This evidence has called for the adoption of a pathology spectrum-based approach to study neurodegenerative proteinopathies. These conditions share brain deposition of abnormal protein aggregates, leading to aberrant biochemical, metabolic, functional, and structural changes. Positron emission tomography (PET) is a well-recognized and unique tool for the in vivo assessment of brain neuropathology, and novel PET techniques are emerging for the study of specific protein species. Today, key applications of PET range from early research and clinical diagnostic tools to their use in clinical trials for both participants screening and outcome evaluation. This position article critically reviews the role of distinct PET molecular tracers for different neurodegenerative proteinopathies, highlighting their strengths, weaknesses, and opportunities, with special emphasis on methodological challenges and future applications.
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Affiliation(s)
- Daniela Perani
- Vita-Salute San Raffaele University, Nuclear Medicine Unit San Raffaele Hospital, Division of Neuroscience San Raffaele Scientific Institute, Milan, Italy
| | - Leonardo Iaccarino
- Vita-Salute San Raffaele University, Nuclear Medicine Unit San Raffaele Hospital, Division of Neuroscience San Raffaele Scientific Institute, Milan, Italy
| | - Adriaan A Lammertsma
- Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands
| | - Albert D Windhorst
- Department of Radiology and Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands
| | - Paul Edison
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK; Neurology Imaging Unit, Imperial College London, London, UK
| | - Ronald Boellaard
- Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centres, Amsterdam, The Netherlands
| | - Oskar Hansson
- Clinical Memory Research Unit, Department of Clinical Sciences, Lund University, Lund, Sweden; Memory Clinic, Skåne University Hospital, Malmö, Sweden
| | - Agneta Nordberg
- Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Center for Alzheimer Research, Stockholm, Sweden
| | - Andreas H Jacobs
- European Institute for Molecular Imaging, University of Münster, Münster, Germany; Evangelische Kliniken Bonn gGmbH, Johanniter Krankenhaus, Bonn, Germany.
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23
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Wilson H, Pagano G, Politis M. Dementia spectrum disorders: lessons learnt from decades with PET research. J Neural Transm (Vienna) 2019; 126:233-251. [PMID: 30762136 PMCID: PMC6449308 DOI: 10.1007/s00702-019-01975-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 01/21/2019] [Indexed: 02/07/2023]
Abstract
The dementia spectrum encompasses a range of disorders with complex diagnosis, pathophysiology and limited treatment options. Positron emission tomography (PET) imaging provides insights into specific neurodegenerative processes underlying dementia disorders in vivo. Here we focus on some of the most common dementias: Alzheimer’s disease, Parkinsonism dementias including Parkinson’s disease with dementia, dementia with Lewy bodies, progressive supranuclear palsy and corticobasal syndrome, and frontotemporal lobe degeneration. PET tracers have been developed to target specific proteinopathies (amyloid, tau and α-synuclein), glucose metabolism, cholinergic system and neuroinflammation. Studies have shown distinct imaging abnormalities can be detected early, in some cases prior to symptom onset, allowing disease progression to be monitored and providing the potential to predict symptom onset. Furthermore, advances in PET imaging have identified potential therapeutic targets and novel methods to accurately discriminate between different types of dementias in vivo. There are promising imaging markers with a clinical application on the horizon, however, further studies are required before they can be implantation into clinical practice.
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Affiliation(s)
- Heather Wilson
- Neurodegeneration Imaging Group, Maurice Wohl Clinical Neuroscience Institute, 125 Coldharbour Lane, Camberwell, London, SE5 9NU, UK
| | - Gennaro Pagano
- Neurodegeneration Imaging Group, Maurice Wohl Clinical Neuroscience Institute, 125 Coldharbour Lane, Camberwell, London, SE5 9NU, UK
| | - Marios Politis
- Neurodegeneration Imaging Group, Maurice Wohl Clinical Neuroscience Institute, 125 Coldharbour Lane, Camberwell, London, SE5 9NU, UK.
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Carter SF, Herholz K, Rosa-Neto P, Pellerin L, Nordberg A, Zimmer ER. Astrocyte Biomarkers in Alzheimer's Disease. Trends Mol Med 2019; 25:77-95. [PMID: 30611668 DOI: 10.1016/j.molmed.2018.11.006] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/30/2018] [Accepted: 11/30/2018] [Indexed: 01/01/2023]
Abstract
Astrocytic contributions to Alzheimer's disease (AD) progression were, until recently, largely overlooked. Astrocytes are integral to normal brain function and astrocyte reactivity is an early feature of AD, potentially providing a promising target for preclinical diagnosis and treatment. Several in vivo AD biomarkers already exist, but presently there is a paucity of specific and sensitive in vivo astrocyte biomarkers that can accurately measure preclinical AD. Measuring monoamine oxidase-B with neuroimaging and glial fibrillary acidic protein from bodily fluids are biomarkers that are currently available. Developing novel, more specific, and sensitive astrocyte biomarkers will make it possible to pharmaceutically target chemical pathways that preserve beneficial astrocytic functions in response to AD pathology. This review discusses astrocyte biomarkers in the context of AD.
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Affiliation(s)
- Stephen F Carter
- Wolfson Molecular Imaging Centre, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
| | - Karl Herholz
- Wolfson Molecular Imaging Centre, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
| | - Pedro Rosa-Neto
- Translational Neuroimaging Laboratory, McGill Centre for Studies in Aging, McGill University, Montreal, Canada; Douglas Hospital Research Centre, Montreal, Canada; Montreal Neurological Institute, Montreal, Canada
| | - Luc Pellerin
- Département de Physiologie, Université de Lausanne, Lausanne, Switzerland; Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536 CNRS, LabEx TRAIL-IBIO, Université de Bordeaux, Bordeaux Cedex 33760, France
| | - Agneta Nordberg
- Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, Stockholm, Sweden; Theme Aging, Karolinska University Hospital, Huddinge, Sweden
| | - Eduardo R Zimmer
- Department of Pharmacology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Graduate Program in Biological Sciences: Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Graduate Program in Biological Sciences: Pharmacology and Therapeutics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Brain Institute (BraIns) of Rio Grande do Sul, Porto Alegre, Brazil; Website: www.zimmer-lab.org.
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25
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Molecular Imaging in Huntington's Disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2018; 142:289-333. [PMID: 30409256 DOI: 10.1016/bs.irn.2018.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Huntington's disease (HD) is a rare monogenic neurodegenerative disorder caused by a trinucleotide CAG repeat expansion in the huntingtin gene resulting in the formation of intranuclear inclusions of mutated huntingtin. The accumulation of mutated huntingtin leads to loss of GABAergic medium spiny neurons (MSNs); subsequently resulting in the development of chorea, cognitive dysfunction and psychiatric symptoms. Premanifest HD gene expansion carriers, provide a unique cohort to examine very early molecular changes, occurring before the development of overt symptoms, to elucidate disease pathophysiology and identify reliable biomarkers of HD progression. Positron emission tomography (PET) is a non-invasive molecular imaging technique allowing the evaluation of specific molecular targets in vivo. Selective PET radioligands provide invaluable tools to investigate the role of the dopaminergic system, brain metabolism, microglial activation, phosphodiesterase 10A, and cannabinoid, GABA, adenosine and opioid receptors in HD. PET has been employed to monitor disease progression aiming to identify a reliable biomarker to predict phenoconversion from premanifest to manifest HD.
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Tyacke RJ, Myers JFM, Venkataraman A, Mick I, Turton S, Passchier J, Husbands SM, Rabiner EA, Gunn RN, Murphy PS, Parker CA, Nutt DJ. Evaluation of 11C-BU99008, a PET Ligand for the Imidazoline 2 Binding Site in Human Brain. J Nucl Med 2018; 59:1597-1602. [PMID: 29523627 DOI: 10.2967/jnumed.118.208009] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 02/21/2018] [Indexed: 11/16/2022] Open
Abstract
The imidazoline2 binding site (I2BS) is thought to be expressed in glia and implicated in the regulation of glial fibrillary acidic protein. A PET ligand for this target would be important for the investigation of neurodegenerative and neuroinflammatory diseases. 11C-BU99008 has previously been identified as a putative PET radioligand. Here, we present the first in vivo characterization of this PET radioligand in humans and assess its test-retest reproducibility. Methods: Fourteen healthy male volunteers underwent dynamic PET imaging with 11C-BU99008 and arterial sampling. Six subjects were used in a test-retest assessment, and 8 were used in a pharmacologic evaluation, undergoing a second or third heterologous competition scan with the mixed I2BS/α2-adrenoceptor drug idazoxan (n = 8; 20, 40, 60, and 80 mg) and the mixed irreversible monoamine oxidase type A/B inhibitor isocarboxazid (n = 4; 50 mg). Regional time-activity data were generated from arterial plasma input functions corrected for metabolites using the most appropriate model to derive the outcome measure VT (regional distribution volume). All image processing and kinetic analyses were performed in MIAKAT. Results: Brain uptake of 11C-BU99008 was good, with reversible kinetics and a heterogeneous distribution consistent with known I2BS expression. Model selection criteria indicated that the 2-tissue-compartment model was preferred. VT estimates were high in the striatum (105 ± 21 mL⋅cm-3), medium in the cingulate cortex (62 ± 10 mL⋅cm-3), and low in the cerebellum (41 ± 7 mL⋅cm-3). Test-retest reliability was reasonable. The uptake was dose-dependently reduced throughout the brain by pretreatment with idazoxan, with an average block across all regions of about 60% (VT, ∼30 mL⋅cm-3) at the highest dose (80 mg). The median effective dose for idazoxan was 28 mg. Uptake was not blocked by pretreatment with the monoamine oxidase inhibitor isocarboxazid. Conclusion:11C-BU99008 in human PET studies demonstrates good brain delivery, reversible kinetics, heterogeneous distribution, specific binding signal consistent with I2BS distribution, and good test-retest reliability.
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Affiliation(s)
- Robin J Tyacke
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, London, United Kingdom
| | - Jim F M Myers
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, London, United Kingdom
| | - Ashwin Venkataraman
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, London, United Kingdom
| | - Inge Mick
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, London, United Kingdom
| | - Samuel Turton
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, London, United Kingdom
| | - Jan Passchier
- Imanova Limited, Imperial College London, London, United Kingdom
| | - Stephen M Husbands
- Department of Pharmacy and Pharmacology, University of Bath, Bath, United Kingdom
| | | | - Roger N Gunn
- Imanova Limited, Imperial College London, London, United Kingdom
- Restorative Neurosciences, Imperial College London, London, United Kingdom; and
| | - Philip S Murphy
- Experimental Medicine Imaging, GlaxoSmithKline Research and Development Limited, Stevenage, United Kingdom
| | - Christine A Parker
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, London, United Kingdom
- Experimental Medicine Imaging, GlaxoSmithKline Research and Development Limited, Stevenage, United Kingdom
| | - David J Nutt
- Neuropsychopharmacology Unit, Centre for Academic Psychiatry, Division of Brain Sciences, Imperial College London, London, United Kingdom
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Current Clinical Practice Patterns of Self-Identified Nuclear Medicine Specialists. AJR Am J Roentgenol 2018; 211:978-985. [PMID: 30085843 DOI: 10.2214/ajr.18.20005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE The objective of our study was to study patterns of services rendered by U.S. physicians who self-identify as nuclear medicine (NM) specialists. MATERIALS AND METHODS Recent Medicare physician claims and demographic files were obtained and linked. NM specialists were defined as physicians self-identifying NM as their primary specialty on claims or as any of their specialties during enrollment. Using other self-identified specialties, we classified physicians as nuclear radiologists, nuclear cardiologists, exclusively NM physicians, or Others. Our primary outcome measure was the percentage of NM effort (in work relative value units [WRVUs]) per physician per specialty group. Secondary outcome measures included physician sociodemographic parameters and most common uniquely rendered services. RESULTS Nationally, 1583 physicians self-identified as NM specialists during the calendar years 2012 through 2015. The distribution of WRVUs attributed to NM varied widely by specialty group; most nuclear radiologists and nuclear cardiologists devoted 10% or less of their effort to NM services whereas most NM physicians devoted 90% or more of their effort to NM services. NM specialists were most commonly nuclear radiologists (52.2%) and men (80.3%) and practiced in urban (98.4%) and nonacademic settings (62.9%). NM physicians interpreted more general NM studies, nuclear radiologists interpreted more cross-sectional imaging studies, and nuclear cardiologists interpreted mostly nuclear cardiology studies, with a majority of their overall work attributed to clinical evaluation and management (E/M). E/M services accounted for less than 2% of WRVUs for both nuclear radiologists and NM physicians. CONCLUSION The work patterns of U.S. NM specialists is highly variable. Most NM physicians practice 90% or more NM, whereas most nuclear radiologists and nuclear cardiologists practice 10% or less NM. Commonly performed services vary considerably by specialty group.
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Edison P, Donat CK, Sastre M. In vivo Imaging of Glial Activation in Alzheimer's Disease. Front Neurol 2018; 9:625. [PMID: 30131755 PMCID: PMC6090997 DOI: 10.3389/fneur.2018.00625] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/10/2018] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by memory loss and decline of cognitive function, associated with progressive neurodegeneration. While neuropathological processes like amyloid plaques and tau neurofibrillary tangles have been linked to neuronal death in AD, the precise role of glial activation on disease progression is still debated. It was suggested that neuroinflammation could occur well ahead of amyloid deposition and may be responsible for clearing amyloid, having a neuroprotective effect; however, later in the disease, glial activation could become deleterious, contributing to neuronal toxicity. Recent genetic and preclinical studies suggest that the different activation states of microglia and astrocytes are complex, not as polarized as previously thought, and that the heterogeneity in their phenotype can switch during disease progression. In the last few years, novel imaging techniques e.g., new radiotracers for assessing glia activation using positron emission tomography and advanced magnetic resonance imaging technologies have emerged, allowing the correlation of neuro-inflammatory markers with cognitive decline, brain function and brain pathology in vivo. Here we review all new imaging technology in AD patients and animal models that has the potential to serve for early diagnosis of the disease, to monitor disease progression and to test the efficacy and the most effective time window for potential anti-inflammatory treatments.
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Affiliation(s)
- Paul Edison
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
| | - Cornelius K Donat
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
| | - Magdalena Sastre
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
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Venkataraman AV, Keat N, Myers JF, Turton S, Mick I, Gunn RN, Rabiner EA, Passchier J, Parker CA, Tyacke RJ, Nutt DJ. First evaluation of PET-based human biodistribution and radiation dosimetry of 11C-BU99008, a tracer for imaging the imidazoline 2 binding site. EJNMMI Res 2018; 8:71. [PMID: 30062395 PMCID: PMC6066589 DOI: 10.1186/s13550-018-0429-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 07/18/2018] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND We measured whole body distribution of 11C-BU99008, a new PET biomarker for non-invasive identification of the imidazoline2 binding site. The purpose of this phase I study was to evaluate the biodistribution and radiation dosimetry of 11C-BU99008 in healthy human subjects. METHODS A single bolus injection of 11C-BU99008 (296 ± 10.5 MBq) was administered to four healthy subjects who underwent whole-body PET/CT over 120 min from the cranial vertex to the mid-thigh. Volumes of interest were drawn around visually identifiable source organs to generate time-activity curves (TAC). Residence times were determined from time-activity curves. Absorbed doses to individual organs and the whole body effective dose were calculated using OLINDA/EXM 1.1 for each subject. RESULTS The highest measured activity concentration was in the kidney and spleen. The longest residence time was in the muscle at 0.100 ± 0.023 h, followed by the liver at 0.067 ± 0.015 h and lungs at 0.052 ± 0.010 h. The highest mean organ absorbed dose was within the heart wall (0.028 ± 0.002 mGy/MBq), followed by the kidneys (0.026 ± 0.005 mGy/MBq). The critical organ was the heart wall. The total mean effective dose averaged over subjects was estimated to be 0.0056 ± 0.0004 mSv/MBq for an injection of 11C-BU99008. CONCLUSIONS The biodistribution of 11C-BU99008 has been shown here for the first time in humans. Our dosimetry data showed the total mean effective dose over all subjects was 0.0056 ± 0.0004 mSv/MBq, which would result in a total effective dose of 1.96 mSv for a typical injection of 350 MBq of 11C-BU99008. The effective dose is not appreciably different from those obtained with other 11C tracers.
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Affiliation(s)
- Ashwin V. Venkataraman
- Neuropsychopharmacology Unit, Centre for Psychiatry, Division of Brain Sciences, Imperial College London, 5th Floor Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, W12 0NN UK
- Restorative Neurosciences, Imperial College London, Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, W12 0NN UK
| | - Nicholas Keat
- Imanova Limited, Imperial College London, Hammersmith Hospital, Burlington Danes Building, Du Cane Road, London, W12 0NN UK
| | - James F. Myers
- Neuropsychopharmacology Unit, Centre for Psychiatry, Division of Brain Sciences, Imperial College London, 5th Floor Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, W12 0NN UK
| | - Samuel Turton
- Neuropsychopharmacology Unit, Centre for Psychiatry, Division of Brain Sciences, Imperial College London, 5th Floor Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, W12 0NN UK
| | - Inge Mick
- Neuropsychopharmacology Unit, Centre for Psychiatry, Division of Brain Sciences, Imperial College London, 5th Floor Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, W12 0NN UK
| | - Roger N. Gunn
- Imanova Limited, Imperial College London, Hammersmith Hospital, Burlington Danes Building, Du Cane Road, London, W12 0NN UK
- Restorative Neurosciences, Imperial College London, Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, W12 0NN UK
| | - Eugenii A. Rabiner
- Imanova Limited, Imperial College London, Hammersmith Hospital, Burlington Danes Building, Du Cane Road, London, W12 0NN UK
| | - Jan Passchier
- Imanova Limited, Imperial College London, Hammersmith Hospital, Burlington Danes Building, Du Cane Road, London, W12 0NN UK
| | - Christine A. Parker
- Neuropsychopharmacology Unit, Centre for Psychiatry, Division of Brain Sciences, Imperial College London, 5th Floor Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, W12 0NN UK
- Experimental Medicine Imaging, GlaxoSmithKline Research & Development Limited, Gunnels Wood Road, Stevenage, SG1 2NY UK
| | - Robin J. Tyacke
- Neuropsychopharmacology Unit, Centre for Psychiatry, Division of Brain Sciences, Imperial College London, 5th Floor Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, W12 0NN UK
| | - David J. Nutt
- Neuropsychopharmacology Unit, Centre for Psychiatry, Division of Brain Sciences, Imperial College London, 5th Floor Burlington Danes Building, Hammersmith Hospital campus, 160 Du Cane Road, London, W12 0NN UK
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Change in the Binding of [ 11C]BU99008 to Imidazoline I 2 Receptor Using Brain PET in Zucker Rats. Mol Imaging Biol 2018; 21:105-112. [PMID: 29736564 DOI: 10.1007/s11307-018-1206-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
PURPOSE The imdazoline I2 receptor (I2R) has been found in the feeding centers of the brain, such as the hypothalamus, and certain I2R ligands have been reported to stimulate food intake. Thus, it has been proposed that I2R may play a role in feeding control. [11C]BU99008 was developed as a positron emission tomography (PET) tracer for imaging of I2R. [11C]BU99008 displayed relatively high brain penetration and specific binding by brain PET studies in preclinical studies. Here, we evaluated a pathological condition caused by obesity related to I2R function by quantitative PET study using [11C]BU99008. PROCEDURES PET scans were acquired in the Zucker (ZUC) lean and fatty rats, radioactivity and metabolites of plasma were measured, and the kinetic parameters were estimated. RESULTS Radioactivity levels after the injection of [11C]BU99008 in the hypothalamus of both ZUC lean and fatty rats were highly accumulated, and then gradually decreased until 60 min after the injection. The accumulated radioactivity from 30 to 60 min after the injection in the hypothalamus of the ZUC fatty rats was 1.3 times greater than that of lean rats. The volume of distribution (VT) estimated by Logan graphical analysis in the hypothalamus of the ZUC fatty rats was 1.8 times greater than that in the ZUC lean rats. In metabolite analysis, the percentages of the unchanged form in the plasma of the ZUC fatty rats at 60 min after the injection (5.0 %) was significantly lower than that of lean rats (9.1 %). CONCLUSIONS By PET imaging using [11C]BU99008, we demonstrated that the accumulated radioactivity and estimated VT value in the feeding center of ZUC lean rats was lower than that in fatty rats. PET studies using [11C]BU99008 may contribute to elucidate a pathological condition caused by obesity related to I2R function.
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Benítez J, García D, Romero N, González A, Martínez-Oyanedel J, Figueroa M, Salas M, López V, García-Robles M, Dodd PR, Schenk G, Carvajal N, Uribe E. Metabolic strategies for the degradation of the neuromodulator agmatine in mammals. Metabolism 2018; 81:35-44. [PMID: 29162499 DOI: 10.1016/j.metabol.2017.11.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 10/23/2017] [Accepted: 11/08/2017] [Indexed: 01/08/2023]
Abstract
Agmatine (1-amino-4-guanidinobutane), a precursor for polyamine biosynthesis, has been identified as an important neuromodulator with anticonvulsant, antineurotoxic and antidepressant actions in the brain. In this context it has emerged as an important mediator of addiction/satiety pathways associated with alcohol misuse. Consequently, the regulation of the activity of key enzymes in agmatine metabolism is an attractive strategy to combat alcoholism and related addiction disorders. Agmatine results from the decarboxylation of L-arginine in a reaction catalyzed by arginine decarboxylase (ADC), and can be converted to either guanidine butyraldehyde by diamine oxidase (DAO) or putrescine and urea by the enzyme agmatinase (AGM) or the more recently identified AGM-like protein (ALP). In rat brain, agmatine, AGM and ALP are predominantly localised in areas associated with roles in appetitive and craving (drug-reinstatement) behaviors. Thus, inhibitors of AGM or ALP are promising agents for the treatment of addictions. In this review, the properties of DAO, AGM and ALP are discussed with a view to their role in the agmatine metabolism in mammals.
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Affiliation(s)
- José Benítez
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - David García
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Nicol Romero
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Arlette González
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - José Martínez-Oyanedel
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Maximiliano Figueroa
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Mónica Salas
- Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, Chile
| | - Vasthi López
- Departamento de Ciencias Biomédicas, Universidad Católica del Norte, Coquimbo, Chile
| | - María García-Robles
- Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Peter R Dodd
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Gerhard Schenk
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nelson Carvajal
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile
| | - Elena Uribe
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile.
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Rodriguez-Vieitez E, Nordberg A. Imaging Neuroinflammation: Quantification of Astrocytosis in a Multitracer PET Approach. Methods Mol Biol 2018; 1750:231-251. [PMID: 29512077 DOI: 10.1007/978-1-4939-7704-8_16] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The recent progress in the development of in vivo biomarkers is rapidly changing how neurodegenerative diseases are conceptualized and diagnosed, and how clinical trials are designed today. Alzheimer's disease (AD)-the most common neurodegenerative disorder-is characterized by a complex neuropathology involving the deposition of extracellular amyloid-β (Aβ) plaques and intracellular neurofibrillary tangles (NFT) of hyperphosphorylated tau proteins, accompanied by the activation of glial cells-astrocytes and microglia-and neuroinflammatory responses, leading to neurodegeneration and cognitive dysfunction. An increasing diversity of positron emission tomography (PET) imaging radiotracers are available to selectively target the different pathophysiological processes of AD. Along with the success of Aβ PET and the more recent tau PET imaging, there is also a great interest to develop PET tracers to image glial activation and neuroinflammation. While most research to date has focused on imaging microgliosis, recent studies using 11C-deuterium-L-deprenyl (11C-DED) PET imaging suggest that astrocytosis may be present from very early stages of disease development in AD. This chapter provides a detailed description of the practical approach used for the analysis of 11C-DED PET imaging data in a multitracer PET paradigm including 11C-Pittsburgh compound B (11C-PiB) and 18F-fluorodeoxyglucose (18F-FDG). The multitracer PET approach allows investigating the comparative regional and temporal patterns of in vivo brain astrocytosis, fibrillar Aβ deposition, and glucose metabolism in patients at different stages of disease progression. This chapter attempts to stimulate further research in the field, including the development of novel PET tracers that may allow visualizing different aspects of the complex astrocytic and microglial responses in neurodegenerative diseases. Progress in the field will contribute to the incorporation of PET imaging of glial activation and neuroinflammation as biomarkers with clinical application, and motivate further investigation on glial cells as therapeutic targets in AD and other neurodegenerative diseases.
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Affiliation(s)
- Elena Rodriguez-Vieitez
- Division of Translational Alzheimer Neurobiology, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden.
| | - Agneta Nordberg
- Division of Translational Alzheimer Neurobiology, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
- Department of Geriatric Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden
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Das TK, Dey A, Sabesan P, Javadzadeh A, Théberge J, Radua J, Palaniyappan L. Putative Astroglial Dysfunction in Schizophrenia: A Meta-Analysis of 1H-MRS Studies of Medial Prefrontal Myo-Inositol. Front Psychiatry 2018; 9:438. [PMID: 30298023 PMCID: PMC6160540 DOI: 10.3389/fpsyt.2018.00438] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 08/24/2018] [Indexed: 11/22/2022] Open
Abstract
Background: Several lines of evidence support a role for astroglial pathology in schizophrenia. Myo-inositol is particularly abundant in astroglia. Many small sized studies have reported on myo-inositol concentration in schizophrenia, but to date these have not been pooled to estimate a collective effect size. Methods: We reviewed all proton magnetic resonance spectroscopy (1H-MRS) studies reporting myo-inositol values for patients satisfying DSM or ICD based criteria for schizophrenia in comparison to a healthy controls group in the medial prefrontal cortex published until February 2018. A random-effects model was used to calculate the pooled effect size using metafor package. A meta-regression analysis of moderator variables was also undertaken. Results: The literature search identified 19 studies published with a total sample size of 585 controls, 561 patients with schizophrenia. Patients with schizophrenia had significantly reduced medial prefrontal myo-inositol compared to controls (RFX standardized mean difference = 0.19, 95% CI [0.05-0.32], z = 2.72, p = 0.0067; heterogeneity p = 0.09). Studies with more female patients reported more notable schizophrenia-related reduction in myo-inositol (z = 2.53, p = 0.011). Discussion: We report a small, but significant reduction in myo-inositol concentration in the medial prefrontal cortex in schizophrenia. The size of the reported effect indicates that the biological pathways affecting the astroglia are likely to operate only in a subset of patients with schizophrenia. MRS myo-inositol could be a useful tool to stratify and investigate such patients.
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Affiliation(s)
- Tushar Kanti Das
- Department of Psychiatry, University of Western Ontario, London, ON, Canada.,Robarts Research Institute, London, ON, Canada.,Lawson Health Research Institute, London, ON, Canada
| | - Avyarthana Dey
- Department of Psychiatry, University of Western Ontario, London, ON, Canada.,Robarts Research Institute, London, ON, Canada
| | | | - Alborz Javadzadeh
- Department of Psychiatry, University of Western Ontario, London, ON, Canada
| | - Jean Théberge
- Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, University of Western Ontario, London, ON, Canada
| | - Joaquim Radua
- FIDMAG Germanes Hospitalàries, CIBERSAM, Sant Boi de Llobregat & Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Lena Palaniyappan
- Department of Psychiatry, University of Western Ontario, London, ON, Canada.,Robarts Research Institute, London, ON, Canada.,Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, University of Western Ontario, London, ON, Canada
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Molecular Imaging of Neuroinflammation in Idiopathic Parkinson's Disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2018; 141:347-363. [DOI: 10.1016/bs.irn.2018.08.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Narayanaswami V, Dahl K, Bernard-Gauthier V, Josephson L, Cumming P, Vasdev N. Emerging PET Radiotracers and Targets for Imaging of Neuroinflammation in Neurodegenerative Diseases: Outlook Beyond TSPO. Mol Imaging 2018; 17:1536012118792317. [PMID: 30203712 PMCID: PMC6134492 DOI: 10.1177/1536012118792317] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 05/31/2018] [Accepted: 07/09/2018] [Indexed: 11/16/2022] Open
Abstract
The dynamic and multicellular processes of neuroinflammation are mediated by the nonneuronal cells of the central nervous system, which include astrocytes and the brain's resident macrophages, microglia. Although initiation of an inflammatory response may be beneficial in response to injury of the nervous system, chronic or maladaptive neuroinflammation can have harmful outcomes in many neurological diseases. An acute neuroinflammatory response is protective when activated neuroglia facilitate tissue repair by releasing anti-inflammatory cytokines and neurotrophic factors. On the other hand, chronic neuroglial activation is a major pathological mechanism in neurodegenerative diseases, likely contributing to neuronal dysfunction, injury, and disease progression. Therefore, the development of specific and sensitive probes for positron emission tomography (PET) studies of neuroinflammation is attracting immense scientific and clinical interest. An early phase of this research emphasized PET studies of the prototypical imaging biomarker of glial activation, translocator protein-18 kDa (TSPO), which presents difficulties for quantitation and lacks absolute cellular specificity. Many alternate molecular targets present themselves for PET imaging of neuroinflammation in vivo, including enzymes, intracellular signaling molecules as well as ionotropic, G-protein coupled, and immunoglobulin receptors. We now review the lead structures in radiotracer development for PET studies of neuroinflammation targets for neurodegenerative diseases extending beyond TSPO, including glycogen synthase kinase 3, monoamine oxidase-B, reactive oxygen species, imidazoline-2 binding sites, cyclooxygenase, the phospholipase A2/arachidonic acid pathway, sphingosine-1-phosphate receptor-1, cannabinoid-2 receptor, the chemokine receptor CX3CR1, purinergic receptors: P2X7 and P2Y12, the receptor for advanced glycation end products, Mer tyrosine kinase, and triggering receptor expressed on myeloid cells-1. We provide a brief overview of the cellular expression and function of these targets, noting their selectivity for astrocytes and/or microglia, and highlight the classes of PET radiotracers that have been investigated in early-stage preclinical or clinical research studies of neuroinflammation.
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Affiliation(s)
- Vidya Narayanaswami
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health & Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Kenneth Dahl
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health & Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Vadim Bernard-Gauthier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Paul Cumming
- School of Psychology and Counselling and IHBI, Queensland University of Technology, Brisbane, Queensland, Australia
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health & Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Department of Radiology, Harvard Medical School, Boston, MA, USA
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Datta G, Violante IR, Scott G, Zimmerman K, Santos-Ribeiro A, Rabiner EA, Gunn RN, Malik O, Ciccarelli O, Nicholas R, Matthews PM. Translocator positron-emission tomography and magnetic resonance spectroscopic imaging of brain glial cell activation in multiple sclerosis. Mult Scler 2016; 23:1469-1478. [PMID: 27903933 DOI: 10.1177/1352458516681504] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND Multiple sclerosis (MS) is characterised by a diffuse inflammatory response mediated by microglia and astrocytes. Brain translocator protein (TSPO) positron-emission tomography (PET) and [myo-inositol] magnetic resonance spectroscopy (MRS) were used together to assess this. OBJECTIVE To explore the in vivo relationships between MRS and PET [11C]PBR28 in MS over a range of brain inflammatory burden. METHODS A total of 23 patients were studied. TSPO PET imaging with [11C]PBR28, single voxel MRS and conventional magnetic resonance imaging (MRI) sequences were undertaken. Disability was assessed by Expanded Disability Status Scale (EDSS) and Multiple Sclerosis Functional Composite (MSFC). RESULTS [11C]PBR28 uptake and [ myo-inositol] were not associated. When the whole cohort was stratified by higher [11C]PBR28 inflammatory burden, [ myo-inositol] was positively correlated to [11C]PBR28 uptake (Spearman's ρ = 0.685, p = 0.014). Moderate correlations were found between [11C]PBR28 uptake and both MRS creatine normalised N-acetyl aspartate (NAA) concentration and grey matter volume. MSFC was correlated with grey matter volume (ρ = 0.535, p = 0.009). There were no associations between other imaging or clinical measures. CONCLUSION MRS [ myo-inositol] and PET [11C]PBR28 measure independent inflammatory processes which may be more commonly found together with more severe inflammatory disease. Microglial activation measured by [11C]PBR28 uptake was associated with loss of neuronal integrity and grey matter atrophy.
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Affiliation(s)
- Gourab Datta
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - Ines R Violante
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - Gregory Scott
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - Karl Zimmerman
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - Andre Santos-Ribeiro
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - Eugenii A Rabiner
- Imanova Ltd, Imperial College London, London, UK/Centre for Neuroimaging Sciences, King's College London, London, UK
| | - Roger N Gunn
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK/manova Ltd, Imperial College London, London, UK
| | - Omar Malik
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - Olga Ciccarelli
- Queen Square Multiple Sclerosis Centre, Institute of Neurology, University College London, London, UK
| | - Richard Nicholas
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
| | - Paul M Matthews
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK
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Kawamura K, Shimoda Y, Yui J, Zhang Y, Yamasaki T, Wakizaka H, Hatori A, Xie L, Kumata K, Fujinaga M, Ogawa M, Kurihara Y, Nengaki N, Zhang MR. A useful PET probe [ 11C]BU99008 with ultra-high specific radioactivity for small animal PET imaging of I 2-imidazoline receptors in the hypothalamus. Nucl Med Biol 2016; 45:1-7. [PMID: 27835825 DOI: 10.1016/j.nucmedbio.2016.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 10/14/2016] [Accepted: 10/24/2016] [Indexed: 01/23/2023]
Abstract
INTRODUCTION A positron emission tomography (PET) probe with ultra-high specific radioactivity (SA) enables measuring high receptor specific binding in brain regions by avoiding mass effect of the PET probe itself. It has been reported that PET probe with ultra-high SA can detect small change caused by endogenous or exogenous ligand. Recently, Kealey et al. developed [11C]BU99008, a more potent PET probe for I2-imidazoline receptors (I2Rs) imaging, with a conventional SA (mean 76GBq/μmol) showed higher specific binding in the brain. Here, to detect small change of specific binding for I2Rs caused by endogenous or exogenous ligand in an extremely small region, such as hypothalamus in the brain, we synthesized and evaluated [11C]BU99008 with ultra-high SA as a useful PET probe for small-animal PET imaging of I2Rs. METHODS [11C]BU99008 was prepared by [11C]methylation of N-desmethyl precursor with [11C]methyl iodide. Biodistribution, metabolite analysis, and brain PET studies were conducted in rats. RESULTS [11C]BU99008 with ultra-high SA in the range of 5400-16,600GBq/μmol were successfully synthesized (n=7), and had appropriate radioactivity for in vivo study. In the biodistribution study, the mean radioactivity levels in all investigated tissues except for the kidney did not show significant difference between [11C]BU99008 with ultra-high SA and that with conventional SA. In the metabolite analysis, the percentage of unchanged [11C]BU99008 at 30min after the injection of probes with ultra-high and conventional SA was similar in rat brain and plasma. In the PET study of rats' brain, radioactivity level (AUC30-60 min) in the hypothalamus of rats injected with [11C]BU99008 with ultra-high SA (64 [SUV ∙ min]) was significantly higher than that observed for that with conventional SA (50 [SUV ∙ min]). The specific binding of [11C]BU99008 with ultra-high SA (86% of total binding) for I2R was higher than that of conventional SA (76% of total binding). CONCLUSION A PET study using [11C]BU99008 with ultra-high SA would thus contribute to the detection of small changes in or small regions with I2R expression and hence may be useful in elucidating new functions of I2R.
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Affiliation(s)
- Kazunori Kawamura
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan.
| | - Yoko Shimoda
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Joji Yui
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Yiding Zhang
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Tomoteru Yamasaki
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Hidekatsu Wakizaka
- Department of Medical Physics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Akiko Hatori
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Lin Xie
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Katsushi Kumata
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Masayuki Fujinaga
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Masanao Ogawa
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan; SHI Accelerator Service Ltd., Tokyo 141-0032, Japan
| | - Yusuke Kurihara
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan; SHI Accelerator Service Ltd., Tokyo 141-0032, Japan
| | - Nobuki Nengaki
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan; SHI Accelerator Service Ltd., Tokyo 141-0032, Japan
| | - Ming-Rong Zhang
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
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Matthews PM, Datta G. Positron-emission tomography molecular imaging of glia and myelin in drug discovery for multiple sclerosis. Expert Opin Drug Discov 2015; 10:557-70. [PMID: 25843125 DOI: 10.1517/17460441.2015.1032240] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Therapies acting on glial cells are being explored for new drug development for multiple sclerosis. Molecular imaging using positron-emission tomography (PET) could address relevant questions in early phase clinical trials. AREAS COVERED In this article, the authors critically review human PET methods that can be applied in specialised centres for imaging activated microglia and astrocytes and myelin. EXPERT OPINION Strengths of PET lie in the molecular selectivity, sensitivity and potential for absolute quantitation. Even now, translocator protein PET radioligands could be used in exploratory studies for interventions targeting brain microglial activation. The clinical and neuropathological meaningfulness of signal from PET radioligands reporting on astrocyte activation through cellular expression of either monoamine oxidase B or the I2-imidazoline receptor or metabolism of [(11)C]acetate can now explored. [(11)C] N-methyl-4,4'-diaminostilbene, a PET marker for myelin, could soon enter first human trials. However, use of any of these PET glial markers demands a well-focused hypothesis and a commitment to validation in the context of use. Enhanced access to these radioligands, standardisation of analyses and lowering the costs of using them are needed if their full promise is to be realised.
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Affiliation(s)
- Paul M Matthews
- Imperial College London, Division of Brain Sciences, Department of Medicine , E515, Burlington Danes Building, Du Cane Road, W12 0NN London , UK +44 02075942612 ; +44 02075946548 ;
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In vivo evaluation of a new 18F-labeled PET ligand, [18F]FEBU, for the imaging of I2-imidazoline receptors. Nucl Med Biol 2015; 42:406-12. [DOI: 10.1016/j.nucmedbio.2014.12.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 12/01/2014] [Accepted: 12/19/2014] [Indexed: 11/20/2022]
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