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Bavarsad MS, Grinberg LT. SV2A PET imaging in human neurodegenerative diseases. Front Aging Neurosci 2024; 16:1380561. [PMID: 38699560 PMCID: PMC11064927 DOI: 10.3389/fnagi.2024.1380561] [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: 02/01/2024] [Accepted: 03/20/2024] [Indexed: 05/05/2024] Open
Abstract
This manuscript presents a thorough review of synaptic vesicle glycoprotein 2A (SV2A) as a biomarker for synaptic integrity using Positron Emission Tomography (PET) in neurodegenerative diseases. Synaptic pathology, characterized by synaptic loss, has been linked to various brain diseases. Therefore, there is a need for a minimally invasive approach to measuring synaptic density in living human patients. Several radiotracers targeting synaptic vesicle protein 2A (SV2A) have been created and effectively adapted for use in human subjects through PET scans. SV2A is an integral glycoprotein found in the membranes of synaptic vesicles in all synaptic terminals and is widely distributed throughout the brain. The review delves into the development of SV2A-specific PET radiotracers, highlighting their advancements and limitations in neurodegenerative diseases. Among these tracers, 11C-UCB-J is the most used so far. We summarize and discuss an increasing body of research that compares measurements of synaptic density using SV2A PET with other established indicators of neurodegenerative diseases, including cognitive performance and radiological findings, thus providing a comprehensive analysis of SV2A's effectiveness and reliability as a diagnostic tool in contrast to traditional markers. Although the literature overall suggests the promise of SV2A as a diagnostic and therapeutic monitoring tool, uncertainties persist regarding the superiority of SV2A as a biomarker compared to other available markers. The review also underscores the paucity of studies characterizing SV2A distribution and loss in human brain tissue from patients with neurodegenerative diseases, emphasizing the need to generate quantitative neuropathological maps of SV2A density in cases with neurodegenerative diseases to fully harness the potential of SV2A PET imaging in clinical settings. We conclude by outlining future research directions, stressing the importance of integrating SV2A PET imaging with other biomarkers and clinical assessments and the need for longitudinal studies to track SV2A changes throughout neurodegenerative disease progression, which could lead to breakthroughs in early diagnosis and the evaluation of new treatments.
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Affiliation(s)
| | - Lea T. Grinberg
- Memory and Aging Center, Weill Institute for Neurosciences, University of California, San Francisco (UCSF), San Francisco, CA, United States
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2
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Wang X, Zhang X, Liu J, Zhang J, Liu C, Cui Y, Song Q, Hou Y, Wang Y, Zhang Q, Zhang Y, Fan Y, Jia J, Wang P. Synaptic vesicle glycoprotein 2 A in serum is an ideal biomarker for early diagnosis of Alzheimer's disease. Alzheimers Res Ther 2024; 16:82. [PMID: 38615037 PMCID: PMC11015666 DOI: 10.1186/s13195-024-01440-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 03/26/2024] [Indexed: 04/15/2024]
Abstract
BACKGROUND Previous studies have demonstrated that early intervention was the best plan to inhibit the progression of Alzheimer's disease (AD), which relied on the discovery of early diagnostic biomarkers. In this study, synaptic vesicle glycoprotein 2 A (SV2A) was examined to improve the early diagnostic efficiency in AD. METHODS In this study, biomarker testing was performed through the single-molecule array (Simoa). A total of 121 subjects including cognitively unimpaired controls, amnestic mild cognitive impairment (aMCI), AD and other types of dementia underwent cerebrospinal fluid (CSF) SV2A testing; 430 subjects including health controls, aMCI, AD and other types of dementia underwent serum SV2A, glial fibrillary acidic protein (GFAP), neurofilament light chain (NfL) and p-tau217 testing; 92 subjects including aMCI and AD underwent both CSF SV2A and serum SV2A testing; 115 cognitively unimpaired subjects including APOE ε4 carriers and APOE ε4 non-carriers were tested for serum SV2A, GFAP, NfL and p-tau217. Then, the efficacy of SV2A for the early diagnosis of AD and its ability to identify those at high risk of AD from a cognitively unimpaired population were further analyzed. RESULTS Both CSF and serum SV2A significantly and positively correlated with cognitive performance in patients with AD, and their levels gradually decreased with the progression of AD. Serum SV2A demonstrated excellent diagnostic efficacy for aMCI, with a sensitivity of 97.8%, which was significantly higher than those of NfL, GFAP, and p-tau217. The SV2A-positive rates ranged from 92.86 to 100% in aMCI cases that were negative for the above three biomarkers. Importantly, of all the biomarkers tested, serum SV2A had the highest positivity rate (81.82%) in individuals at risk for AD. CONCLUSIONS Serum SV2A was demonstrated to be a novel and ideal biomarker for the early diagnosis of AD, which can effectively distinguish those at high risk of AD in cognitively unimpaired populations.
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Affiliation(s)
- Xiaoling Wang
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Xiaomin Zhang
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Jing Liu
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Jingjing Zhang
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Congcong Liu
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Yuting Cui
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Qiao Song
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Yuli Hou
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Yaqi Wang
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Qian Zhang
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Yingzhen Zhang
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Yujian Fan
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China
| | - Jianping Jia
- National Clinical Research Center for Geriatric Disorders, 45 Changchun Street, Beijing, 100053, China.
- Innovation Center for Neurological Disorders, Department of Neurology, Xuanwu Hospital, Capital Medical University, 45 Changchun Street, Beijing, 100053, China.
- Beijing Key Laboratory of Geriatric Cognitive Disorders, 45 Changchun Street, Beijing, 100053, China.
- Clinical Center for Neurodegenerative Disease and Memory Impairment, Capital Medical University, 45 Changchun Street, Beijing, 100053, China.
- Center of Alzheimer's Disease, Beijing Institute for Brain Disorders, 45 Changchun Street, Beijing, 100053, China.
- Key Laboratory of Neurodegenerative Diseases, Ministry of Education, 45 Changchun Street, Beijing, 100053, China.
| | - Peichang Wang
- Department of Clinical Laboratory, Xuanwu Hospital, National Clinical Research Center for Geriatric Diseases, Capital Medical University, 45 Changchun Street, Beijing, 100053, China.
- National Clinical Research Center for Geriatric Disorders, 45 Changchun Street, Beijing, 100053, China.
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3
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Martin SL, Uribe C, Strafella AP. PET imaging of synaptic density in Parkinsonian disorders. J Neurosci Res 2024; 102:e25253. [PMID: 37814917 DOI: 10.1002/jnr.25253] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 08/31/2023] [Accepted: 09/21/2023] [Indexed: 10/11/2023]
Abstract
Synaptic dysfunction and altered synaptic pruning are present in people with Parkinsonian disorders. Dopamine loss and alpha-synuclein accumulation, two hallmarks of Parkinson's disease (PD) pathology, contribute to synaptic dysfunction and reduced synaptic density in PD. Atypical Parkinsonian disorders are likely to have unique spatiotemporal patterns of synaptic density, differentiating them from PD. Therefore, quantification of synaptic density has the potential to support diagnoses, monitor disease progression, and treatment efficacy. Novel radiotracers for positron emission tomography which target the presynaptic vesicle protein SV2A have been developed to quantify presynaptic density. The radiotracers have successfully investigated synaptic density in preclinical models of PD and people with Parkinsonian disorders. Therefore, this review will summarize the preclinical and clinical utilization of SV2A radiotracers in people with Parkinsonian disorders. We will evaluate how SV2A abundance is associated with other imaging modalities and the considerations for interpreting SV2A in Parkinsonian pathology.
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Affiliation(s)
- Sarah L Martin
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Carme Uribe
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Unitat de Psicologia Medica, Departament de Medicina, Institute of Neuroscience, Universitat de Barcelona, Barcelona, Spain
| | - Antonio P Strafella
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Edmond J. Safra Parkinson Disease Program, Neurology Division, Toronto Western Hospital & Krembil Brain Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
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4
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Holmes SE, Honhar P, Tinaz S, Naganawa M, Hilmer AT, Gallezot JD, Dias M, Yang Y, Toyonaga T, Esterlis I, Mecca A, Van Dyck C, Henry S, Ropchan J, Nabulsi N, Louis ED, Comley R, Finnema SJ, Carson RE, Matuskey D. Synaptic loss and its association with symptom severity in Parkinson's disease. NPJ Parkinsons Dis 2024; 10:42. [PMID: 38402233 PMCID: PMC10894197 DOI: 10.1038/s41531-024-00655-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 02/06/2024] [Indexed: 02/26/2024] Open
Abstract
Parkinson's disease (PD) is the fastest growing neurodegenerative disease, but at present there is no cure, nor any disease-modifying treatments. Synaptic biomarkers from in vivo imaging have shown promise in imaging loss of synapses in PD and other neurodegenerative disorders. Here, we provide new clinical insights from a cross-sectional, high-resolution positron emission tomography (PET) study of 30 PD individuals and 30 age- and sex-matched healthy controls (HC) with the radiotracer [11C]UCB-J, which binds to synaptic vesicle glycoprotein 2A (SV2A), and is therefore, a biomarker of synaptic density in the living brain. We also examined a measure of relative brain perfusion from the early part of the same PET scan. Our results provide evidence for synaptic density loss in the substantia nigra that had been previously reported, but also extend this to other early-Braak stage regions known to be affected in PD (brainstem, caudate, olfactory cortex). Importantly, we also found a direct association between synaptic density loss in the nigra and severity of symptoms in patients. A greater extent and wider distribution of synaptic density loss in PD patients with longer illness duration suggests that [11C]UCB-J PET can be used to measure synapse loss with disease progression. We also demonstrate lower brain perfusion in PD vs. HC groups, with a greater extent of abnormalities in those with longer duration of illness, suggesting that [11C]UCB-J PET can simultaneously provide information on changes in brain perfusion. These results implicate synaptic imaging as a useful PD biomarker for future disease-modifying interventions.
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Affiliation(s)
- Sophie E Holmes
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Praveen Honhar
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
- Department of Biomedical Engineering, Yale School of Engineering and Applied Sciences, Yale University, New Haven, CT, USA
| | - Sule Tinaz
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | - Mika Naganawa
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
| | - Ansel T Hilmer
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
- Department of Biomedical Engineering, Yale School of Engineering and Applied Sciences, Yale University, New Haven, CT, USA
| | | | - Mark Dias
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
| | - Yanghong Yang
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
| | - Takuya Toyonaga
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
| | - Irina Esterlis
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
| | - Adam Mecca
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
| | | | - Shannan Henry
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
| | - Jim Ropchan
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
| | - Nabeel Nabulsi
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
| | - Elan D Louis
- Department of Neurology, University of Texas Southwestern Medical Center, New Haven, CT, USA
| | | | | | - Richard E Carson
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
- Department of Biomedical Engineering, Yale School of Engineering and Applied Sciences, Yale University, New Haven, CT, USA
| | - David Matuskey
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA.
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
- Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA.
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5
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Drake LR, Wu Y, Naganawa M, Asch R, Zheng C, Najafzadeh S, Pracitto R, Lindemann M, Li S, Ropchan J, Labaree D, Emery PR, Dias M, Henry S, Nabulsi N, Matuskey D, Hillmer AT, Gallezot JD, Carson RE, Cai Z, Huang Y. First-in-Human Study of 18F-SynVesT-2: An SV2A PET Imaging Probe with Fast Brain Kinetics and High Specific Binding. J Nucl Med 2024; 65:jnumed.123.266470. [PMID: 38360052 PMCID: PMC10924160 DOI: 10.2967/jnumed.123.266470] [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: 07/31/2023] [Revised: 12/19/2023] [Accepted: 12/19/2023] [Indexed: 02/17/2024] Open
Abstract
PET imaging of synaptic vesicle glycoprotein 2A allows for noninvasive quantification of synapses. This first-in-human study aimed to evaluate the kinetics, test-retest reproducibility, and extent of specific binding of a recently developed synaptic vesicle glycoprotein 2A PET ligand, (R)-4-(3-(18F-fluoro)phenyl)-1-((3-methylpyridin-4-yl)methyl)pyrrolidine-2-one (18F-SynVesT-2), with fast brain kinetics. Methods: Nine healthy volunteers participated in this study and were scanned on a High Resolution Research Tomograph scanner with 18F-SynVesT-2. Five volunteers were scanned twice on 2 different days. Five volunteers were rescanned with preinjected levetiracetam (20 mg/kg, intravenously). Arterial blood was collected to calculate the plasma free fraction and generate the arterial input function. Individual MR images were coregistered to a brain atlas to define regions of interest for generating time-activity curves, which were fitted with 1- and 2-tissue-compartment (1TC and 2TC) models to derive the regional distribution volume (V T). The regional nondisplaceable binding potential (BP ND) was calculated from 1TC V T, using the centrum semiovale (CS) as the reference region. Results: 18F-SynVesT-2 was synthesized with high molar activity (187 ± 69 MBq/nmol, n = 19). The parent fraction of 18F-SynVesT-2 in plasma was 28% ± 8% at 30 min after injection, and the plasma free fraction was high (0.29 ± 0.04). 18F-SynVesT-2 entered the brain quickly, with an SUVpeak of 8 within 10 min after injection. Regional time-activity curves fitted well with both the 1TC and the 2TC models; however, V T was estimated more reliably using the 1TC model. The 1TC V T ranged from 1.9 ± 0.2 mL/cm3 in CS to 7.6 ± 0.8 mL/cm3 in the putamen, with low absolute test-retest variability (6.0% ± 3.6%). Regional BP ND ranged from 1.76 ± 0.21 in the hippocampus to 3.06 ± 0.29 in the putamen. A 20-min scan was sufficient to provide reliable V T and BP ND Conclusion: 18F-SynVesT-2 has fast kinetics, high specific uptake, and low nonspecific uptake in the brain. Consistent with the nonhuman primate results, the kinetics of 18F-SynVesT-2 is faster than the kinetics of 11C-UCB-J and 18F-SynVesT-1 in the human brain and enables a shorter dynamic scan to derive physiologic information on cerebral blood flow and synapse density.
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Affiliation(s)
| | - Yanjun Wu
- Yale PET Center, New Haven, Connecticut
| | | | - Ruth Asch
- Yale PET Center, New Haven, Connecticut
| | | | | | | | | | - Songye Li
- Yale PET Center, New Haven, Connecticut
| | | | | | | | - Mark Dias
- Yale PET Center, New Haven, Connecticut
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6
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Visser M, O'Brien JT, Mak E. In vivo imaging of synaptic density in neurodegenerative disorders with positron emission tomography: A systematic review. Ageing Res Rev 2024; 94:102197. [PMID: 38266660 DOI: 10.1016/j.arr.2024.102197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 01/09/2024] [Accepted: 01/12/2024] [Indexed: 01/26/2024]
Abstract
Positron emission tomography (PET) with radiotracers that bind to synaptic vesicle glycoprotein 2 A (SV2A) enables quantification of synaptic density in the living human brain. Assessing the regional distribution and severity of synaptic density loss will contribute to our understanding of the pathological processes that precede atrophy in neurodegeneration. In this systematic review, we provide a discussion of in vivo SV2A PET imaging research for quantitative assessment of synaptic density in various dementia conditions: amnestic Mild Cognitive Impairment and Alzheimer's disease, Frontotemporal dementia, Progressive supranuclear palsy and Corticobasal degeneration, Parkinson's disease and Dementia with Lewy bodies, Huntington's disease, and Spinocerebellar Ataxia. We discuss the main findings concerning group differences and clinical-cognitive correlations, and explore relations between SV2A PET and other markers of pathology. Additionally, we touch upon synaptic density in healthy ageing and outcomes of radiotracer validation studies. Studies were identified on PubMed and Embase between 2018 and 2023; last searched on the 3rd of July 2023. A total of 36 studies were included, comprising 5 on normal ageing, 21 clinical studies, and 10 validation studies. Extracted study characteristics were participant details, methodological aspects, and critical findings. In summary, the small but growing literature on in vivo SV2A PET has revealed different spatial patterns of synaptic density loss among various neurodegenerative disorders that correlate with cognitive functioning, supporting the potential role of SV2A PET imaging for differential diagnosis. SV2A PET imaging shows tremendous capability to provide novel insights into the aetiology of neurodegenerative disorders and great promise as a biomarker for synaptic density reduction. Novel directions for future synaptic density research are proposed, including (a) longitudinal imaging in larger patient cohorts of preclinical dementias, (b) multi-modal mapping of synaptic density loss onto other pathological processes, and (c) monitoring therapeutic responses and assessing drug efficacy in clinical trials.
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Affiliation(s)
- Malouke Visser
- Department of Psychiatry, School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, United Kingdom; Neuropsychology and Rehabilitation Psychology, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, the Netherlands
| | - John T O'Brien
- Department of Psychiatry, School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, United Kingdom
| | - Elijah Mak
- Department of Psychiatry, School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, United Kingdom.
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7
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Frigerio I, Bouwman MMA, Noordermeer RTGMM, Podobnik E, Popovic M, Timmermans E, Rozemuller AJM, van de Berg WDJ, Jonkman LE. Regional differences in synaptic degeneration are linked to alpha-synuclein burden and axonal damage in Parkinson's disease and dementia with Lewy bodies. Acta Neuropathol Commun 2024; 12:4. [PMID: 38173031 PMCID: PMC10765668 DOI: 10.1186/s40478-023-01711-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 12/11/2023] [Indexed: 01/05/2024] Open
Abstract
Regional differences in synaptic degeneration may underlie differences in clinical presentation and neuropathological disease progression in Parkinson's Disease (PD) and Dementia with Lewy bodies (DLB). Here, we mapped and quantified synaptic degeneration in cortical brain regions in PD, PD with dementia (PDD) and DLB, and assessed whether regional differences in synaptic loss are linked to axonal degeneration and neuropathological burden. We included a total of 47 brain donors, 9 PD, 12 PDD, 6 DLB and 20 non-neurological controls. Synaptophysin+ and SV2A+ puncta were quantified in eight cortical regions using a high throughput microscopy approach. Neurofilament light chain (NfL) immunoreactivity, Lewy body (LB) density, phosphorylated-tau and amyloid-β load were also quantified. Group differences in synaptic density, and associations with neuropathological markers and Clinical Dementia Rating (CDR) scores, were investigated using linear mixed models. We found significantly decreased synaptophysin and SV2A densities in the cortex of PD, PDD and DLB cases compared to controls. Specifically, synaptic density was decreased in cortical regions affected at Braak α-synuclein stage 5 in PD (middle temporal gyrus, anterior cingulate and insula), and was additionally decreased in cortical regions affected at Braak α-synuclein stage 4 in PDD and DLB compared to controls (entorhinal cortex, parahippocampal gyrus and fusiform gyrus). Synaptic loss associated with higher NfL immunoreactivity and LB density. Global synaptophysin loss associated with longer disease duration and higher CDR scores. Synaptic neurodegeneration occurred in temporal, cingulate and insular cortices in PD, as well as in parahippocampal regions in PDD and DLB. In addition, synaptic loss was linked to axonal damage and severe α-synuclein burden. These results, together with the association between synaptic loss and disease progression and cognitive impairment, indicate that regional synaptic loss may underlie clinical differences between PD and PDD/DLB. Our results might provide useful information for the interpretation of synaptic biomarkers in vivo.
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Affiliation(s)
- Irene Frigerio
- Department of Anatomy and Neurosciences, Section Clinical Neuroanatomy and Biobanking, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1118, Amsterdam, 1081 HV, The Netherlands.
- Amsterdam Neuroscience, Neurodegeneration, Amsterdam, The Netherlands.
- Amsterdam Neuroscience, Brain imaging, Amsterdam, The Netherlands.
| | - Maud M A Bouwman
- Department of Anatomy and Neurosciences, Section Clinical Neuroanatomy and Biobanking, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1118, Amsterdam, 1081 HV, The Netherlands
- Amsterdam Neuroscience, Neurodegeneration, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Brain imaging, Amsterdam, The Netherlands
| | - Ruby T G M M Noordermeer
- Department of Anatomy and Neurosciences, Section Clinical Neuroanatomy and Biobanking, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1118, Amsterdam, 1081 HV, The Netherlands
| | - Ema Podobnik
- Department of Anatomy and Neurosciences, Section Clinical Neuroanatomy and Biobanking, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1118, Amsterdam, 1081 HV, The Netherlands
| | - Marko Popovic
- Department Molecular cell biology & Immunology, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, Netherlands
| | - Evelien Timmermans
- Department of Anatomy and Neurosciences, Section Clinical Neuroanatomy and Biobanking, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1118, Amsterdam, 1081 HV, The Netherlands
| | - Annemieke J M Rozemuller
- Department of Pathology, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1117, Amsterdam, Netherlands
| | - Wilma D J van de Berg
- Department of Anatomy and Neurosciences, Section Clinical Neuroanatomy and Biobanking, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1118, Amsterdam, 1081 HV, The Netherlands
- Amsterdam Neuroscience, Neurodegeneration, Amsterdam, The Netherlands
| | - Laura E Jonkman
- Department of Anatomy and Neurosciences, Section Clinical Neuroanatomy and Biobanking, Amsterdam UMC location Vrije Universiteit Amsterdam, De Boelelaan 1118, Amsterdam, 1081 HV, The Netherlands
- Amsterdam Neuroscience, Neurodegeneration, Amsterdam, The Netherlands
- Amsterdam Neuroscience, Brain imaging, Amsterdam, The Netherlands
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8
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Mohammed OA, Elballal MS, El-Husseiny AA, Khidr EG, El Tabaa MM, Elazazy O, Abd-Elmawla MA, Elesawy AE, Ibrahim HM, Abulsoud AI, El-Dakroury WA, Abdel Mageed SS, Elrebehy MA, Nomier Y, Abdel-Reheim MA, El-Husseiny HM, Mahmoud AMA, Saber S, Doghish AS. Unraveling the role of miRNAs in the diagnosis, progression, and therapeutic intervention of Parkinson's disease. Pathol Res Pract 2024; 253:155023. [PMID: 38081104 DOI: 10.1016/j.prp.2023.155023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Revised: 11/29/2023] [Accepted: 12/06/2023] [Indexed: 01/24/2024]
Abstract
Parkinson's disease (PD) is a debilitating neurological disorder characterized by the impairment of the motor system, resulting in symptoms such as resting tremor, cogwheel rigidity, bradykinesia, difficulty with gait, and postural instability. The occurrence of striatal dopamine insufficiency can be attributed to a notable decline in dopaminergic neurons inside the substantia nigra pars compacta. Additionally, the development of Lewy bodies serves as a pathological hallmark of PD. While current therapy approaches for PD aim to preserve dopaminergic neurons or replenish dopamine levels in the brain, it is important to acknowledge that achieving complete remission of the condition remains elusive. MicroRNAs (miRNAs, miR) are a class of small, non-coding ribonucleic acids involved in regulating gene expression at the post-transcriptional level. The miRNAs play a crucial part in the underlying pathogenic mechanisms of several neurodegenerative illnesses, including PD. The aim of this review is to explore the role of miRNAs in regulating genes associated with the onset and progression of PD, investigate the potential of miRNAs as a diagnostic tool, assess the effectiveness of targeting specific miRNAs as an alternative therapeutic strategy to impede disease advancement, and discuss the utilization of newly developed nanoparticles for delivering miRNAs as neurodegenerative therapies.
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Affiliation(s)
- Osama A Mohammed
- Department of Pharmacology, College of Medicine, University of Bisha, Bisha 61922, Saudi Arabia
| | - Mohammed S Elballal
- Department of Biochemistry, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt
| | - Ahmed A El-Husseiny
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Boys), Al-Azhar University, Nasr City, 11231 Cairo, Egypt; Department of Biochemistry, Faculty of Pharmacy, Egyptian Russian University, Badr City, 11829 Cairo, Egypt
| | - Emad Gamil Khidr
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Boys), Al-Azhar University, Nasr City, 11231 Cairo, Egypt
| | - Manar Mohammed El Tabaa
- Pharmacology & Environmental Toxicology, Environmental Studies & Research Institute (ESRI), University of Sadat City, Sadat City, 32897 Menoufia, Egypt
| | - Ola Elazazy
- Department of Biochemistry, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt
| | - Mai A Abd-Elmawla
- Biochemistry, Department of Biochemistry, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Ahmed E Elesawy
- Department of Biochemistry, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt
| | - Henwa M Ibrahim
- Department of Biochemistry, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt
| | - Ahmed I Abulsoud
- Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Boys), Al-Azhar University, Nasr City, 11231 Cairo, Egypt; Biochemistry Department, Faculty of Pharmacy, Heliopolis University, Cairo 11785, Egypt.
| | - Walaa A El-Dakroury
- Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt
| | - Sherif S Abdel Mageed
- Pharmacology and Toxicology Department, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt
| | - Mahmoud A Elrebehy
- Department of Biochemistry, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt
| | - Yousra Nomier
- Department of Pharmacology and Clinical Pharmacy, College of Medicine and Health Sciences, Sultan Qaboos University, Oman
| | - Mustafa Ahmed Abdel-Reheim
- Department of Pharmaceutical Sciences, College of Pharmacy, Shaqra University, Shaqra 11961, Saudi Arabia; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Beni-Suef University, Beni Suef 62521, Egypt.
| | - Hussein M El-Husseiny
- Laboratory of Veterinary Surgery, Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai Cho, Fuchu-shi, Tokyo 183-8509, Japan; Department of Surgery, Anesthesiology, and Radiology, Faculty of Veterinary Medicine, Benha University, Moshtohor, Toukh, Elqaliobiya 13736, Egypt
| | - Abdulla M A Mahmoud
- Pharmacology and Toxicology Department, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt
| | - Sameh Saber
- Department of Pharmacology, Faculty of Pharmacy, Delta University for Science and Technology, Gamasa 11152, Egypt
| | - Ahmed S Doghish
- Department of Biochemistry, Faculty of Pharmacy, Badr University in Cairo (BUC), Badr City, Cairo 11829, Egypt; Biochemistry and Molecular Biology Department, Faculty of Pharmacy (Boys), Al-Azhar University, Nasr City, 11231 Cairo, Egypt.
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9
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Li A, Yang B, Naganawa M, Fontaine K, Toyonaga T, Carson RE, Tang J. Dose reduction in dynamic synaptic vesicle glycoprotein 2A PET imaging using artificial neural networks. Phys Med Biol 2023; 68:245006. [PMID: 37857316 PMCID: PMC10739622 DOI: 10.1088/1361-6560/ad0535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 10/02/2023] [Accepted: 10/19/2023] [Indexed: 10/21/2023]
Abstract
Objective. Reducing dose in positron emission tomography (PET) imaging increases noise in reconstructed dynamic frames, which inevitably results in higher noise and possible bias in subsequently estimated images of kinetic parameters than those estimated in the standard dose case. We report the development of a spatiotemporal denoising technique for reduced-count dynamic frames through integrating a cascade artificial neural network (ANN) with the highly constrained back-projection (HYPR) scheme to improve low-dose parametric imaging.Approach. We implemented and assessed the proposed method using imaging data acquired with11C-UCB-J, a PET radioligand bound to synaptic vesicle glycoprotein 2A (SV2A) in the human brain. The patch-based ANN was trained with a reduced-count frame and its full-count correspondence of a subject and was used in cascade to process dynamic frames of other subjects to further take advantage of its denoising capability. The HYPR strategy was then applied to the spatial ANN processed image frames to make use of the temporal information from the entire dynamic scan.Main results. In all the testing subjects including healthy volunteers and Parkinson's disease patients, the proposed method reduced more noise while introducing minimal bias in dynamic frames and the resulting parametric images, as compared with conventional denoising methods.Significance. Achieving 80% noise reduction with a bias of -2% in dynamic frames, which translates into 75% and 70% of noise reduction in the tracer uptake (bias, -2%) and distribution volume (bias, -5%) images, the proposed ANN+HYPR technique demonstrates the denoising capability equivalent to a 11-fold dose increase for dynamic SV2A PET imaging with11C-UCB-J.
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Affiliation(s)
- Andi Li
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, United States of America
| | - Bao Yang
- School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, People’s Republic of China
| | - Mika Naganawa
- Positron Emission Tomography Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States of America
| | - Kathryn Fontaine
- Positron Emission Tomography Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States of America
| | - Takuya Toyonaga
- Positron Emission Tomography Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States of America
| | - Richard E Carson
- Positron Emission Tomography Center, Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States of America
| | - Jing Tang
- Department of Biomedical Engineering, University of Cincinnati, Cincinnati, OH, United States of America
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10
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Vijiaratnam N, Foltynie T. How should we be using biomarkers in trials of disease modification in Parkinson's disease? Brain 2023; 146:4845-4869. [PMID: 37536279 PMCID: PMC10690028 DOI: 10.1093/brain/awad265] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/18/2023] [Accepted: 07/22/2023] [Indexed: 08/05/2023] Open
Abstract
The recent validation of the α-synuclein seed amplification assay as a biomarker with high sensitivity and specificity for the diagnosis of Parkinson's disease has formed the backbone for a proposed staging system for incorporation in Parkinson's disease clinical studies and trials. The routine use of this biomarker should greatly aid in the accuracy of diagnosis during recruitment of Parkinson's disease patients into trials (as distinct from patients with non-Parkinson's disease parkinsonism or non-Parkinson's disease tremors). There remain, however, further challenges in the pursuit of biomarkers for clinical trials of disease modifying agents in Parkinson's disease, namely: optimizing the distinction between different α-synucleinopathies; the selection of subgroups most likely to benefit from a candidate disease modifying agent; a sensitive means of confirming target engagement; and the early prediction of longer-term clinical benefit. For example, levels of CSF proteins such as the lysosomal enzyme β-glucocerebrosidase may assist in prognostication or allow enrichment of appropriate patients into disease modifying trials of agents with this enzyme as the target; the presence of coexisting Alzheimer's disease-like pathology (detectable through CSF levels of amyloid-β42 and tau) can predict subsequent cognitive decline; imaging techniques such as free-water or neuromelanin MRI may objectively track decline in Parkinson's disease even in its later stages. The exploitation of additional biomarkers to the α-synuclein seed amplification assay will, therefore, greatly add to our ability to plan trials and assess the disease modifying properties of interventions. The choice of which biomarker(s) to use in the context of disease modifying clinical trials will depend on the intervention, the stage (at risk, premotor, motor, complex) of the population recruited and the aims of the trial. The progress already made lends hope that panels of fluid biomarkers in tandem with structural or functional imaging may provide sensitive and objective methods of confirming that an intervention is modifying a key pathophysiological process of Parkinson's disease. However, correlation with clinical progression does not necessarily equate to causation, and the ongoing validation of quantitative biomarkers will depend on insightful clinical-genetic-pathophysiological comparisons incorporating longitudinal biomarker changes from those at genetic risk with evidence of onset of the pathophysiology and those at each stage of manifest clinical Parkinson's disease.
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Affiliation(s)
- Nirosen Vijiaratnam
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Thomas Foltynie
- Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
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11
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Van Cauwenberge MGA, Delva A, Vande Casteele T, Laroy M, Radwan A, Vansteelandt K, Van den Stock J, Bouckaert F, Van Laere K, Emsell L, Vandenberghe W, Vandenbulcke M. Mild Motor Signs in Healthy Aging Are Associated with Lower Synaptic Density in the Brain. Mov Disord 2023; 38:1786-1794. [PMID: 37574924 DOI: 10.1002/mds.29570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/17/2023] [Accepted: 07/17/2023] [Indexed: 08/15/2023] Open
Abstract
OBJECTIVE To investigate whether mild motor signs (MMS) in old age correlate with synaptic density in the brain. BACKGROUND Normal aging is associated with a decline in movement quality and quantity, commonly termed "mild parkinsonian signs" or more recently MMS. Whether MMS stem from global brain aging or pathology within motor circuits remains unresolved. The synaptic vesicle glycoprotein 2A positron emission tomography (PET) ligand 11 C-UCB-J allows the investigation of brain-motor associations at the synaptic level in vivo. METHOD Fifty-eight healthy older adults (≥50 years) were included from two monocentric control cohorts. Brain magnetic resonance imaging and 11 C-UCB-J PET data were available in 54 participants. 11 C-UCB-J PET binding was quantified by standardized uptake value ratio (SUVR) values in grey matter (GM) volumes of interest (VOIs): caudate, putamen, globus pallidus, substantia nigra, thalamus, cerebellum, and the frontal, parietal, temporal, and occipital cortex. Multiple linear regression analyses were performed with Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III score measuring MMS as the dependent variable and mean SUVR values in each VOI as the independent variable with age, Fazekas score (white matter lesion [WML] load), VOI and cohort as covariates. RESULTS Participants (68 ± 7.5 years; 52% female) had an average MDS-UPDRS part III score of 3.3 ± 2.8. The MDS-UPDRS part III score was inversely associated with synaptic density, independently of WML load or GM volume, in the caudate, substantia nigra, thalamus, cerebellum, and parietal, occipital, temporal cortex. Cohen's f2 showed moderate effect sizes for subcortical (range, 0.30-0.35), cortical (0.28-0.35) and cerebellar VOIs (0.31). CONCLUSION MMS in healthy aging are associated with lower synaptic density throughout the brain. © 2023 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Margot G A Van Cauwenberge
- Department of Neurosciences, Neuropsychiatry, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Department of Neurology, University Hospitals Leuven, Leuven, Belgium
| | - Aline Delva
- Department of Neurology, University Hospitals Leuven, Leuven, Belgium
- Department of Neurosciences, Laboratory for Parkinson Research, Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Thomas Vande Casteele
- Department of Neurosciences, Neuropsychiatry, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Geriatric Psychiatry, University Psychiatric Center KU Leuven, Leuven, Belgium
| | - Maarten Laroy
- Department of Neurosciences, Neuropsychiatry, Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Ahmed Radwan
- Department of Imaging and Pathology, Translational MRI, KU Leuven, Leuven, Belgium
- Department of Radiology, University Hospitals Leuven, Leuven, Belgium
| | - Kristof Vansteelandt
- Department of Neurosciences, Neuropsychiatry, Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Jan Van den Stock
- Department of Neurosciences, Neuropsychiatry, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Geriatric Psychiatry, University Psychiatric Center KU Leuven, Leuven, Belgium
| | - Filip Bouckaert
- Department of Neurosciences, Neuropsychiatry, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Geriatric Psychiatry, University Psychiatric Center KU Leuven, Leuven, Belgium
| | - Koen Van Laere
- Division of Nuclear Medicine, University Hospitals Leuven, Leuven, Belgium
- Department of Imaging and Pathology, Nuclear Medicine and Molecular Imaging, KU Leuven, Leuven, Belgium
| | - Louise Emsell
- Department of Neurosciences, Neuropsychiatry, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Geriatric Psychiatry, University Psychiatric Center KU Leuven, Leuven, Belgium
- Department of Imaging and Pathology, Translational MRI, KU Leuven, Leuven, Belgium
| | - Wim Vandenberghe
- Department of Neurology, University Hospitals Leuven, Leuven, Belgium
- Department of Neurosciences, Laboratory for Parkinson Research, Leuven Brain Institute, KU Leuven, Leuven, Belgium
| | - Mathieu Vandenbulcke
- Department of Neurosciences, Neuropsychiatry, Leuven Brain Institute, KU Leuven, Leuven, Belgium
- Geriatric Psychiatry, University Psychiatric Center KU Leuven, Leuven, Belgium
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12
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Smart K, Uribe C, Desmond KL, Martin SL, Vasdev N, Strafella AP. Preliminary Assessment of Reference Region Quantification and Reduced Scanning Times for [ 18F]SynVesT-1 PET in Parkinson's Disease. Mol Imaging 2023; 2023:1855985. [PMID: 37622164 PMCID: PMC10445483 DOI: 10.1155/2023/1855985] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/02/2023] [Accepted: 07/26/2023] [Indexed: 08/26/2023] Open
Abstract
Synaptic density in the central nervous system can be measured in vivo using PET with [18F]SynVesT-1. While [18F]SynVesT-1 has been proven to be a powerful radiopharmaceutical for PET imaging of neurodegenerative disorders such as Parkinson's disease (PD), its currently validated acquisition and quantification protocols are invasive and technically challenging in these populations due to the arterial sampling and relatively long scanning times. The objectives of this work were to evaluate a noninvasive (reference tissue) quantification method for [18F]SynVesT-1 in PD patients and to determine the minimum scan time necessary for accurate quantification. [18F]SynVesT-1 PET scans were acquired in 5 patients with PD and 3 healthy control subjects for 120 min with arterial blood sampling. Quantification was performed using the one-tissue compartment model (1TCM) with arterial input function, as well as with the simplified reference tissue model (SRTM) to estimate binding potential (BPND) using centrum semiovale (CS) as a reference region. The SRTM2 method was used with k2' fixed to either a sample average value (0.037 min-1) or a value estimated first through coupled fitting across regions for each participant. Direct SRTM estimation and the Logan reference region graphical method were also evaluated. There were no significant group differences in CS volume, radiotracer uptake, or efflux (ps > 0.47). Each fitting method produced BPND estimates in close agreement with those derived from the 1TCM (subject R2s > 0.98, bias < 10%), with no difference in bias between the control and PD groups. With SRTM2, BPND estimates from truncated scan data as short as 80 min produced values in excellent agreement with the data from the full 120 min scans (bias < 6%). While these are preliminary results from a small sample of patients with PD (n = 5), this work suggests that accurate synaptic density quantification may be performed without blood sampling and with scan time under 90 minutes. If further validated, these simplified procedures for [18F]SynVesT-1 PET quantification can facilitate its application as a clinical research imaging technology and allow for larger study samples and include a broader scope of patients including those with neurodegenerative diseases.
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Affiliation(s)
- Kelly Smart
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON, Canada M5T 1R8
- Department of Psychiatry, University of Toronto, 250 College St., Toronto, ON, Canada M5T 1R8
| | - Carme Uribe
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON, Canada M5T 1R8
- Unitat de Psicologia Medica, Departament de Medicina, Institute of Neuroscience, Universitat de Barcelona, Barcelona, Spain
| | - Kimberly L. Desmond
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON, Canada M5T 1R8
- Department of Psychiatry, University of Toronto, 250 College St., Toronto, ON, Canada M5T 1R8
| | - Sarah L. Martin
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON, Canada M5T 1R8
| | - Neil Vasdev
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON, Canada M5T 1R8
- Department of Psychiatry, University of Toronto, 250 College St., Toronto, ON, Canada M5T 1R8
| | - Antonio P. Strafella
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON, Canada M5T 1R8
- Edmond J. Safra Parkinson Disease Program, Neurology Division, Toronto Western Hospital & Krembil Brain Institute, University Health Network, University of Toronto, 399 Bathurst Street, Toronto, ON, Canada M5T 2S8
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13
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Wang T, Jia H. The Sigma Receptors in Alzheimer's Disease: New Potential Targets for Diagnosis and Therapy. Int J Mol Sci 2023; 24:12025. [PMID: 37569401 PMCID: PMC10418732 DOI: 10.3390/ijms241512025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/14/2023] [Accepted: 07/16/2023] [Indexed: 08/13/2023] Open
Abstract
Sigma (σ) receptors are a class of unique proteins with two subtypes: the sigma-1 (σ1) receptor which is situated at the mitochondria-associated endoplasmic reticulum (ER) membrane (MAM), and the sigma-2 (σ2) receptor, located in the ER-resident membrane. Increasing evidence indicates the involvement of both σ1 and σ2 receptors in the pathogenesis of Alzheimer's disease (AD), and thus these receptors represent two potentially effective biomarkers for emerging AD therapies. The availability of optimal radioligands for positron emission tomography (PET) neuroimaging of the σ1 and σ2 receptors in humans will provide tools to monitor AD progression and treatment outcomes. In this review, we first summarize the significance of both receptors in the pathophysiology of AD and highlight AD therapeutic strategies related to the σ1 and σ2 receptors. We then survey the potential PET radioligands, with an emphasis on the requirements of optimal radioligands for imaging the σ1 or σ2 receptors in humans. Finally, we discuss current challenges in the development of PET radioligands for the σ1 or σ2 receptors, and the opportunities for neuroimaging to elucidate the σ1 and σ2 receptors as novel biomarkers for early AD diagnosis, and for monitoring of disease progression and AD drug efficacy.
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Affiliation(s)
- Tao Wang
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China;
- Department of Nuclear Medicine, Xinqiao Hospital, Army Medical University, Chongqing 400037, China
| | - Hongmei Jia
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China;
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14
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Pizarro-Galleguillos BM, Kunert L, Brüggemann N, Prasuhn J. Neuroinflammation and Mitochondrial Dysfunction in Parkinson's Disease: Connecting Neuroimaging with Pathophysiology. Antioxidants (Basel) 2023; 12:1411. [PMID: 37507950 PMCID: PMC10375976 DOI: 10.3390/antiox12071411] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/07/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
There is a pressing need for disease-modifying therapies in patients suffering from neurodegenerative diseases, including Parkinson's disease (PD). However, these disorders face unique challenges in clinical trial designs to assess the neuroprotective properties of potential drug candidates. One of these challenges relates to the often unknown individual disease mechanisms that would, however, be relevant for targeted treatment strategies. Neuroinflammation and mitochondrial dysfunction are two proposed pathophysiological hallmarks and are considered to be highly interconnected in PD. Innovative neuroimaging methods can potentially help to gain deeper insights into one's predominant disease mechanisms, can facilitate patient stratification in clinical trials, and could potentially map treatment responses. This review aims to highlight the role of neuroinflammation and mitochondrial dysfunction in patients with PD (PwPD). We will specifically introduce different neuroimaging modalities, their respective technical hurdles and challenges, and their implementation into clinical practice. We will gather preliminary evidence for their potential use in PD research and discuss opportunities for future clinical trials.
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Affiliation(s)
- Benjamin Matís Pizarro-Galleguillos
- Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile
- Department of Neurology, University Medical Center Schleswig-Holstein, Campus Lübeck, 23562 Lübeck, Germany
- Institute of Neurogenetics, University of Lübeck, 23562 Lübeck, Germany
- Center for Brain, Behavior, and Metabolism, University of Lübeck, 23562 Lübeck, Germany
| | - Liesa Kunert
- Department of Neurology, University Medical Center Schleswig-Holstein, Campus Lübeck, 23562 Lübeck, Germany
- Institute of Neurogenetics, University of Lübeck, 23562 Lübeck, Germany
- Center for Brain, Behavior, and Metabolism, University of Lübeck, 23562 Lübeck, Germany
| | - Norbert Brüggemann
- Department of Neurology, University Medical Center Schleswig-Holstein, Campus Lübeck, 23562 Lübeck, Germany
- Center for Brain, Behavior, and Metabolism, University of Lübeck, 23562 Lübeck, Germany
| | - Jannik Prasuhn
- Department of Neurology, University Medical Center Schleswig-Holstein, Campus Lübeck, 23562 Lübeck, Germany
- Institute of Neurogenetics, University of Lübeck, 23562 Lübeck, Germany
- Center for Brain, Behavior, and Metabolism, University of Lübeck, 23562 Lübeck, Germany
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD 21287, USA
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15
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Lopresti BJ, Royse SK, Mathis CA, Tollefson SA, Narendran R. Beyond monoamines: I. Novel targets and radiotracers for Positron emission tomography imaging in psychiatric disorders. J Neurochem 2023; 164:364-400. [PMID: 35536762 DOI: 10.1111/jnc.15615] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 10/18/2022]
Abstract
With the emergence of positron emission tomography (PET) in the late 1970s, psychiatry had access to a tool capable of non-invasive assessment of human brain function. Early applications in psychiatry focused on identifying characteristic brain blood flow and metabolic derangements using radiotracers such as [15 O]H2 O and [18 F]FDG. Despite the success of these techniques, it became apparent that more specific probes were needed to understand the neurochemical bases of psychiatric disorders. The first neurochemical PET imaging probes targeted sites of action of neuroleptic (dopamine D2 receptors) and psychoactive (serotonin receptors) drugs. Based on the centrality of monoamine dysfunction in psychiatric disorders and the measured success of monoamine-enhancing drugs in treating them, the next 30 years witnessed the development of an armamentarium of PET radiopharmaceuticals and imaging methodologies for studying monoamines. Continued development of monoamine-enhancing drugs over this time however was less successful, realizing only modest gains in efficacy and tolerability. As patent protection for many widely prescribed and profitable psychiatric drugs lapsed, drug development pipelines shifted away from monoamines in search of novel targets with the promises of improved efficacy, or abandoned altogether. Over this period, PET radiopharmaceutical development activities closely paralleled drug development priorities resulting in the development of new PET imaging agents for non-monoamine targets. Part one of this review will briefly survey novel PET imaging targets with relevance to the field of psychiatry, which include the metabotropic glutamate receptor type 5 (mGluR5), purinergic P2 X7 receptor, type 1 cannabinoid receptor (CB1 ), phosphodiesterase 10A (PDE10A), and describe radiotracers developed for these and other targets that have matured to human subject investigations. Current limitations of the targets and techniques will also be discussed.
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Affiliation(s)
- Brian J Lopresti
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Sarah K Royse
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Chester A Mathis
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Savannah A Tollefson
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Rajesh Narendran
- Departments of Radiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA.,Departments of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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16
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Chaperone-Dependent Mechanisms as a Pharmacological Target for Neuroprotection. Int J Mol Sci 2023; 24:ijms24010823. [PMID: 36614266 PMCID: PMC9820882 DOI: 10.3390/ijms24010823] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/26/2022] [Accepted: 12/27/2022] [Indexed: 01/05/2023] Open
Abstract
Modern pharmacotherapy of neurodegenerative diseases is predominantly symptomatic and does not allow vicious circles causing disease development to break. Protein misfolding is considered the most important pathogenetic factor of neurodegenerative diseases. Physiological mechanisms related to the function of chaperones, which contribute to the restoration of native conformation of functionally important proteins, evolved evolutionarily. These mechanisms can be considered promising for pharmacological regulation. Therefore, the aim of this review was to analyze the mechanisms of endoplasmic reticulum stress (ER stress) and unfolded protein response (UPR) in the pathogenesis of neurodegenerative diseases. Data on BiP and Sigma1R chaperones in clinical and experimental studies of Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Huntington's disease are presented. The possibility of neuroprotective effect dependent on Sigma1R ligand activation in these diseases is also demonstrated. The interaction between Sigma1R and BiP-associated signaling in the neuroprotection is discussed. The performed analysis suggests the feasibility of pharmacological regulation of chaperone function, possibility of ligand activation of Sigma1R in order to achieve a neuroprotective effect, and the need for further studies of the conjugation of cellular mechanisms controlled by Sigma1R and BiP chaperones.
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17
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Real CC, Binda KH, Thomsen MB, Lillethorup TP, Brooks DJ, Landau AM. Selecting the Best Animal Model of Parkinson's Disease for Your Research Purpose: Insight from in vivo PET Imaging Studies. Curr Neuropharmacol 2023; 21:1241-1272. [PMID: 36797611 PMCID: PMC10286593 DOI: 10.2174/1570159x21666230216101659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/08/2022] [Accepted: 09/08/2022] [Indexed: 02/18/2023] Open
Abstract
Parkinson's disease (PD) is a debilitating neurodegenerative multisystem disorder leading to motor and non-motor symptoms in millions of individuals. Despite intense research, there is still no cure, and early disease biomarkers are lacking. Animal models of PD have been inspired by basic elements of its pathogenesis, such as dopamine dysfunction, alpha-synuclein accumulation, neuroinflammation and disruption of protein degradation, and these have been crucial for a deeper understanding of the mechanisms of pathology, the identification of biomarkers, and evaluation of novel therapies. Imaging biomarkers are non-invasive tools to assess disease progression and response to therapies; their discovery and validation have been an active field of translational research. Here, we highlight different considerations of animal models of PD that can be applied to future research, in terms of their suitability to answer different research questions. We provide the reader with important considerations of the best choice of model to use based on the disease features of each model, including issues related to different species. In addition, positron emission tomography studies conducted in PD animal models in the last 5 years are presented. With a variety of different species, interventions and genetic information, the choice of the most appropriate model to answer research questions can be daunting, especially since no single model recapitulates all aspects of this complex disorder. Appropriate animal models in conjunction with in vivo molecular imaging tools, if selected properly, can be a powerful combination for the assessment of novel therapies and developing tools for early diagnosis.
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Affiliation(s)
- Caroline Cristiano Real
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Karina Henrique Binda
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Majken Borup Thomsen
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Thea Pinholt Lillethorup
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - David James Brooks
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
- Institute of Translational and Clinical Research, University of Newcastle, Upon Tyne, UK
| | - Anne Marlene Landau
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
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18
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Prange S, Theis H, Banwinkler M, van Eimeren T. Molecular Imaging in Parkinsonian Disorders—What’s New and Hot? Brain Sci 2022; 12:brainsci12091146. [PMID: 36138882 PMCID: PMC9496752 DOI: 10.3390/brainsci12091146] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/23/2022] [Accepted: 08/24/2022] [Indexed: 12/02/2022] Open
Abstract
Highlights Abstract Neurodegenerative parkinsonian disorders are characterized by a great diversity of clinical symptoms and underlying neuropathology, yet differential diagnosis during lifetime remains probabilistic. Molecular imaging is a powerful method to detect pathological changes in vivo on a cellular and molecular level with high specificity. Thereby, molecular imaging enables to investigate functional changes and pathological hallmarks in neurodegenerative disorders, thus allowing to better differentiate between different forms of degenerative parkinsonism, improve the accuracy of the clinical diagnosis and disentangle the pathophysiology of disease-related symptoms. The past decade led to significant progress in the field of molecular imaging, including the development of multiple new and promising radioactive tracers for single photon emission computed tomography (SPECT) and positron emission tomography (PET) as well as novel analytical methods. Here, we review the most recent advances in molecular imaging for the diagnosis, prognosis, and mechanistic understanding of parkinsonian disorders. First, advances in imaging of neurotransmission abnormalities, metabolism, synaptic density, inflammation, and pathological protein aggregation are reviewed, highlighting our renewed understanding regarding the multiplicity of neurodegenerative processes involved in parkinsonian disorders. Consequently, we review the role of molecular imaging in the context of disease-modifying interventions to follow neurodegeneration, ensure stratification, and target engagement in clinical trials.
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Affiliation(s)
- Stéphane Prange
- Multimodal Neuroimaging Group, Department of Nuclear Medicine, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
- Institut des Sciences Cognitives Marc Jeannerod, CNRS, UMR 5229, Université de Lyon, 69675 Bron, France
- Correspondence: (S.P.); (T.v.E.); Tel.: +49-221-47882843 (T.v.E.)
| | - Hendrik Theis
- Multimodal Neuroimaging Group, Department of Nuclear Medicine, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
- Department of Neurology, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
| | - Magdalena Banwinkler
- Multimodal Neuroimaging Group, Department of Nuclear Medicine, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
| | - Thilo van Eimeren
- Multimodal Neuroimaging Group, Department of Nuclear Medicine, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
- Department of Neurology, Faculty of Medicine, University Hospital of Cologne, University of Cologne, 50937 Cologne, Germany
- Correspondence: (S.P.); (T.v.E.); Tel.: +49-221-47882843 (T.v.E.)
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19
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Delva A, Van Laere K, Vandenberghe W. Longitudinal Positron Emission Tomography Imaging of Presynaptic Terminals in Early Parkinson's Disease. Mov Disord 2022; 37:1883-1892. [PMID: 35819412 DOI: 10.1002/mds.29148] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/31/2022] [Accepted: 06/16/2022] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Imaging tools that allow quantification of Parkinson's disease (PD) progression could facilitate the development of disease-modifying therapies. Cross-sectional studies have shown presynaptic terminal damage in PD patients, but longitudinal data are limited. OBJECTIVES The aim of this study was to longitudinally assess loss of presynaptic terminals in general and dopaminergic presynaptic terminals in particular as measures of disease progression in early PD. METHODS A total of 27 patients with early PD and 18 age- and sex-matched healthy controls underwent positron emission tomography (PET) with 11 C-UCB-J, a ligand for the brain-wide presynaptic terminal marker SV2A, and with 18 F-FE-PE2I, a highly selective dopamine transporter ligand, in combination with a comprehensive motor and non-motor clinical assessment at baseline (BL) and after 26.5 ± 2.1 months (Y2). SUVR-1 images were calculated and volumes of interest were delineated based on individual 3D T1 magnetic resonance imaging (MRI). RESULTS PD patients showed significant 2-year worsening of Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale Part III (MDS-UPDRS-III) (off medication) scores, but not of non-motor scores. Motor and non-motor scores in controls did not change significantly over 2 years. 18 F-FE-PE2I binding in caudate and putamen showed significant 2-year decline in the PD group and remained unchanged in controls. Longitudinal decline of striatal 18 F-FE-PE2I binding in PD did not correlate with longitudinal changes in MDS-UPDRS-III scores. 11 C-UCB-J PET did not show any region with significant 2-year change in PD or controls. CONCLUSIONS 18 F-FE-PE2I PET showed robust 2-year decline in early PD, but 11 C-UCB-J PET did not. Longitudinal changes in 18 F-FE-PE2I binding did not correlate with clinical motor progression. © 2022 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Aline Delva
- Department of Neurosciences, KU Leuven, Leuven, Belgium.,Department of Neurology, University Hospitals Leuven, Leuven, Belgium
| | - Koen Van Laere
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium.,Division of Nuclear Medicine, University Hospitals Leuven, Leuven, Belgium
| | - Wim Vandenberghe
- Department of Neurosciences, KU Leuven, Leuven, Belgium.,Department of Neurology, University Hospitals Leuven, Leuven, Belgium
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20
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Prasuhn J, Kunert L, Brüggemann N. Neuroimaging Methods to Map In Vivo Changes of OXPHOS and Oxidative Stress in Neurodegenerative Disorders. Int J Mol Sci 2022; 23:ijms23137263. [PMID: 35806267 PMCID: PMC9266616 DOI: 10.3390/ijms23137263] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 06/24/2022] [Accepted: 06/25/2022] [Indexed: 12/11/2022] Open
Abstract
Mitochondrial dysfunction is a pathophysiological hallmark of most neurodegenerative diseases. Several clinical trials targeting mitochondrial dysfunction have been performed with conflicting results. Reliable biomarkers of mitochondrial dysfunction in vivo are thus needed to optimize future clinical trial designs. This narrative review highlights various neuroimaging methods to probe mitochondrial dysfunction. We provide a general overview of the current biological understanding of mitochondrial dysfunction in degenerative brain disorders and how distinct neuroimaging methods can be employed to map disease-related changes. The reviewed methodological spectrum includes positron emission tomography, magnetic resonance, magnetic resonance spectroscopy, and near-infrared spectroscopy imaging, and how these methods can be applied to study alterations in oxidative phosphorylation and oxidative stress. We highlight the advantages and shortcomings of the different neuroimaging methods and discuss the necessary steps to use these for future research. This review stresses the importance of neuroimaging methods to gain deepened insights into mitochondrial dysfunction in vivo, its role as a critical disease mechanism in neurodegenerative diseases, the applicability for patient stratification in interventional trials, and the quantification of individual treatment responses. The in vivo assessment of mitochondrial dysfunction is a crucial prerequisite for providing individualized treatments for neurodegenerative disorders.
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Affiliation(s)
- Jannik Prasuhn
- Institute of Neurogenetics, University of Lübeck, 23538 Lübeck, Germany; (J.P.); (L.K.)
- Department of Neurology, University Medical Center Schleswig Holstein, Campus Lübeck, 23538 Lübeck, Germany
- Center for Brain, Behavior and Metabolism, University of Lübeck, 23562 Lübeck, Germany
| | - Liesa Kunert
- Institute of Neurogenetics, University of Lübeck, 23538 Lübeck, Germany; (J.P.); (L.K.)
- Department of Neurology, University Medical Center Schleswig Holstein, Campus Lübeck, 23538 Lübeck, Germany
- Center for Brain, Behavior and Metabolism, University of Lübeck, 23562 Lübeck, Germany
| | - Norbert Brüggemann
- Institute of Neurogenetics, University of Lübeck, 23538 Lübeck, Germany; (J.P.); (L.K.)
- Department of Neurology, University Medical Center Schleswig Holstein, Campus Lübeck, 23538 Lübeck, Germany
- Center for Brain, Behavior and Metabolism, University of Lübeck, 23562 Lübeck, Germany
- Correspondence: ; Tel.: +49-451-500-43420; Fax: +49-451-500-43424
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21
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Wilson H, de Natale ER, Politis M. Concise Review: Recent advances in neuroimaging techniques to assist clinical trials on cell-based therapies in neurodegenerative diseases. Stem Cells 2022; 40:724-735. [PMID: 35671344 DOI: 10.1093/stmcls/sxac039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 05/17/2022] [Indexed: 11/14/2022]
Abstract
Neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), are progressive disorders for which a curative therapy is still lacking. Cell-based therapy aims at replacing dysfunctional cellular populations by repairing damaged tissue and by enriching the microenvironment of selective brain areas, and thus constitutes a promising disease-modifying treatment of neurodegenerative diseases. Scientific research has engineered a wide range of human-derived cellular populations to help overcome some of the logistical, safety, and ethical issues associated with this approach. Open-label studies and clinical trials in human participants have employed neuroimaging techniques, such as positron emission tomography (PET) and magnetic resonance imaging (MRI), to assess the success of the transplantation, to evaluate the functional integration of the implanted tissue into the host environment and to understand the pathophysiological changes associated with the therapy. Neuroimaging has constituted an outcome measure of large, randomized clinical trials, and has given answers to clarify the pathophysiology underlying some of the complications linked with this therapy. Novel PET radiotracers and MRI sequences for the staging of neurodegenerative diseases and to study alterations at molecular level significantly expands the translational potential of neuroimaging to assist pre-clinical and clinical research on cell-based therapy in these disorders. This concise review summarizes the current use of neuroimaging in human studies of cell-based replacement therapy and focuses on future application of PET and MRI techniques to evaluate the pathophysiology and treatment efficacy, as well as to aid patient selection and as an outcome measure to improve treatment success.
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Affiliation(s)
- Heather Wilson
- Neurodegeneration Imaging Group, University of Exeter Medical School, London, UK
| | | | - Marios Politis
- Neurodegeneration Imaging Group, University of Exeter Medical School, London, UK
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22
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Barthel H, Villemagne VL, Drzezga A. Future Directions in Molecular Imaging of Neurodegenerative Disorders. J Nucl Med 2022; 63:68S-74S. [PMID: 35649650 DOI: 10.2967/jnumed.121.263202] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/19/2022] [Indexed: 12/12/2022] Open
Abstract
The improvement of existing techniques and the development of new molecular imaging methods are an exciting and rapidly developing field in clinical care and research of neurodegenerative disorders. In the clinic, molecular imaging has the potential to improve early and differential diagnosis and to stratify and monitor therapy in these disorders. Meanwhile, in research, these techniques improve our understanding of the underlying pathophysiology and pathobiochemistry of these disorders and allow for drug testing. This article is an overview on our perspective on future developments in neurodegeneration tracers and the associated imaging technologies. For example, we predict that the current portfolio of β-amyloid and tau aggregate tracers will be improved and supplemented by tracers allowing imaging of other protein aggregation pathologies, such as α-synuclein and transactive response DNA binding protein 43 kDa. Future developments will likely also be observed in imaging neurotransmitter systems. This refers to both offering imaging to a broader population in cases involving the dopaminergic, cholinergic, and serotonergic systems and making possible the imaging of systems not yet explored, such as the glutamate and opioid systems. Tracers will be complemented by improved tracers of neuroinflammation and synaptic density. Technologywise, the use of hybrid PET/MRI, dedicated brain PET, and total-body PET scanners, as well as advanced image acquisition and processing protocols, will open doors toward broader and more efficient clinical use and novel research applications. Molecular imaging has the potential of becoming a standard and essential clinical and research tool to diagnose and study neurodegenerative disorders and to guide treatments. On that road, we will need to redefine the role of molecular imaging in relation to that of emerging blood-based biomarkers. Taken together, the unique features of molecular imaging-that is, the potential to provide direct noninvasive information on the presence, extent, localization, and quantity of molecular pathologic processes in the living body-together with the predicted novel tracer and imaging technology developments, provide optimism about a bright future for this approach to improved care and research on neurodegenerative disorders.
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Affiliation(s)
- Henryk Barthel
- Department of Nuclear Medicine, University Medical Center, University of Leipzig, Leipzig, Germany;
| | - Victor L Villemagne
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Alexander Drzezga
- Department of Nuclear Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, German Center for Neurodegenerative Diseases, Bonn, Germany, and Institute of Neuroscience and Medicine, Molecular Organization of the Brain, Forschungszentrum Jülich, Jülich, Germany
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23
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Carson RE, Naganawa M, Toyonaga T, Koohsari S, Yang Y, Chen MK, Matuskey D, Finnema SJ. Imaging of Synaptic Density in Neurodegenerative Disorders. J Nucl Med 2022; 63:60S-67S. [PMID: 35649655 DOI: 10.2967/jnumed.121.263201] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/10/2022] [Indexed: 02/07/2023] Open
Abstract
PET technology has produced many radiopharmaceuticals that target specific brain proteins and other measures of brain function. Recently, a new approach has emerged to image synaptic density by targeting the synaptic vesicle protein 2A (SV2A), an integral glycoprotein in the membrane of synaptic vesicles and widely distributed throughout the brain. Multiple SV2A ligands have been developed and translated to human use. The most successful of these to date is 11C-UCB-J, because of its high uptake, moderate metabolism, and effective quantification with a 1-tissue-compartment model. Further, since SV2A is the target of the antiepileptic drug levetiracetam, human blocking studies have characterized specific binding and potential reference regions. Regional brain SV2A levels were shown to correlate with those of synaptophysin, another commonly used marker of synaptic density, providing the basis for SV2A PET imaging to have broad utility across neuropathologic diseases. In this review, we highlight the development of SV2A tracers and the evaluation of quantification methods, including compartment modeling and simple tissue ratios. Mouse and rat models of neurodegenerative diseases have been studied with small-animal PET, providing validation by comparison to direct tissue measures. Next, we review human PET imaging results in multiple neurodegenerative disorders. Studies on Parkinson disease and Alzheimer disease have progressed most rapidly at multiple centers, with generally consistent results of patterns of SV2A or synaptic loss. In Alzheimer disease, the synaptic loss patterns differ from those of amyloid, tau, and 18F-FDG, although intertracer and interregional correlations have been found. Smaller studies have been reported in other disorders, including Lewy body dementia, frontotemporal dementia, Huntington disease, progressive supranuclear palsy, and corticobasal degeneration. In conclusion, PET imaging of SV2A has rapidly developed, and qualified radioligands are available. PET studies on humans indicate that SV2A loss might be specific to disease-associated brain regions and consistent with synaptic density loss. The recent availability of new 18F tracers, 18F-SynVesT-1 and 18F-SynVesT-2, will substantially broaden the application of SV2A PET. Future studies are needed in larger patient cohorts to establish the clinical value of SV2A PET and its potential for diagnosis and progression monitoring of neurodegenerative diseases, as well as efficacy assessment of disease-modifying therapies.
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Affiliation(s)
- Richard E Carson
- Department of Radiology and Biomedical Imaging, Yale Positron Emission Tomography Center, Yale University, New Haven, Connecticut;
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut
| | - Mika Naganawa
- Department of Radiology and Biomedical Imaging, Yale Positron Emission Tomography Center, Yale University, New Haven, Connecticut
| | - Takuya Toyonaga
- Department of Radiology and Biomedical Imaging, Yale Positron Emission Tomography Center, Yale University, New Haven, Connecticut
| | - Sheida Koohsari
- Department of Radiology and Biomedical Imaging, Yale Positron Emission Tomography Center, Yale University, New Haven, Connecticut
| | - Yanghong Yang
- Department of Radiology and Biomedical Imaging, Yale Positron Emission Tomography Center, Yale University, New Haven, Connecticut
| | - Ming-Kai Chen
- Department of Radiology and Biomedical Imaging, Yale Positron Emission Tomography Center, Yale University, New Haven, Connecticut
| | - David Matuskey
- Department of Radiology and Biomedical Imaging, Yale Positron Emission Tomography Center, Yale University, New Haven, Connecticut
- Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut; and
| | - Sjoerd J Finnema
- Neuroscience Discovery Research, Translational Imaging, AbbVie, North Chicago, Illinois
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24
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Rossi R, Arjmand S, Bærentzen SL, Gjedde A, Landau AM. Synaptic Vesicle Glycoprotein 2A: Features and Functions. Front Neurosci 2022; 16:864514. [PMID: 35573314 PMCID: PMC9096842 DOI: 10.3389/fnins.2022.864514] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/05/2022] [Indexed: 01/05/2023] Open
Abstract
In recent years, the field of neuroimaging dramatically moved forward by means of the expeditious development of specific radioligands of novel targets. Among these targets, the synaptic vesicle glycoprotein 2A (SV2A) is a transmembrane protein of synaptic vesicles, present in all synaptic terminals, irrespective of neurotransmitter content. It is involved in key functions of neurons, focused on the regulation of neurotransmitter release. The ubiquitous expression in gray matter regions of the brain is the basis of its candidacy as a marker of synaptic density. Following the development of molecules derived from the structure of the anti-epileptic drug levetiracetam, which selectively binds to SV2A, several radiolabeled markers have been synthetized to allow the study of SV2A distribution with positron emission tomography (PET). These radioligands permit the evaluation of in vivo changes of SV2A distribution held to be a potential measure of synaptic density in physiological and pathological conditions. The use of SV2A as a biomarker of synaptic density raises important questions. Despite numerous studies over the last decades, the biological function and the expressional properties of SV2A remain poorly understood. Some functions of SV2A were claimed, but have not been fully elucidated. While the expression of SV2A is ubiquitous, stronger associations between SV2A and Υ amino butyric acid (GABA)-ergic rather than glutamatergic synapses were observed in some brain structures. A further issue is the unclear interaction between SV2A and its tracers, which reflects a need to clarify what really is detected with neuroimaging tools. Here, we summarize the current knowledge of the SV2A protein and we discuss uncertain aspects of SV2A biology and physiology. As SV2A expression is ubiquitous, but likely more strongly related to a certain type of neurotransmission in particular circumstances, a more extensive knowledge of the protein would greatly facilitate the analysis and interpretation of neuroimaging results by allowing the evaluation not only of an increase or decrease of the protein level, but also of the type of neurotransmission involved.
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Affiliation(s)
- Rachele Rossi
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Shokouh Arjmand
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Simone Larsen Bærentzen
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
| | - Albert Gjedde
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.,Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
| | - Anne M Landau
- Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Nuclear Medicine and PET Center, Aarhus University Hospital, Aarhus, Denmark
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25
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Kaczor AA, Wojtunik-Kulesza K, Wróbel TM, Matosiuk D, Pitucha M. 5-Methoxy-1-methyl-2-{[4-(2-hydroxyphenyl)piperazin-1-yl]methyl}-1Hindole (KAD22) with Antioxidant Activity. LETT ORG CHEM 2022. [DOI: 10.2174/1570178618666210119121438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
:
Compound KAD22 (5-methoxy-1-methyl-2-[4-(2-hydroxyphenyl)piperazin-1-yl]methyl-1H-indole) was designed as a potential dopamine D2 receptor agonist with antioxidant activity for possible treatment of Parkinson’s disease.
The compound was obtained from 5-methoxy-1-methyl-1H-indole-2-carbaldehyde and 2-(piperazin-1-yl)phenol. KAD22
showed no affinity to dopamine D2 receptor but it is a potent antioxidant. Experimental and computational structural studies
(conformational analysis, HOMO and LUMO orbitals, electrostatic potential map, non-covalent interaction plot, spectral
properties, ligand-receptor interactions) of KAD22 were performed to address its biological activity.
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Affiliation(s)
- Agnieszka A. Kaczor
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances, Faculty of Pharmacy, Medical
University of Lublin, 4A Chodzki St., PL-20093 Lublin, Poland
| | - Karolina Wojtunik-Kulesza
- Department of Inorganic Chemistry, Faculty of
Pharmacy, Medical University of Lublin, 4A Chodzki St., PL-20093 Lublin, Poland
| | - Tomasz M. Wróbel
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances, Faculty of Pharmacy, Medical
University of Lublin, 4A Chodzki St., PL-20093 Lublin, Poland
| | - Dariusz Matosiuk
- Department of Synthesis and Chemical Technology of Pharmaceutical Substances, Faculty of Pharmacy, Medical
University of Lublin, 4A Chodzki St., PL-20093 Lublin, Poland
| | - Monika Pitucha
- Independent Radiopharmacy Unit,
Department of Organic Chemistry, Faculty of Pharmacy, Medical University of Lublin, 4A Chodzki St., PL-20093
Lublin, Poland
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26
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Flønes IH, Tzoulis C. Mitochondrial Respiratory Chain Dysfunction—A Hallmark Pathology of Idiopathic Parkinson’s Disease? Front Cell Dev Biol 2022; 10:874596. [PMID: 35433702 PMCID: PMC9010539 DOI: 10.3389/fcell.2022.874596] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 03/10/2022] [Indexed: 12/21/2022] Open
Abstract
Parkinson’s disease (PD) is the most common age-dependent neurodegenerative synucleinopathy. Loss of dopaminergic neurons of the substantia nigra pars compacta, together with region- and cell-specific aggregations of α-synuclein are considered main pathological hallmarks of PD, but its etiopathogenesis remains largely unknown. Mitochondrial dysfunction, in particular quantitative and/or functional deficiencies of the mitochondrial respiratory chain (MRC), has been associated with the disease. However, after decades of research in this field, the pervasiveness and anatomical extent of MRC dysfunction in PD remain largely unknown. Moreover, it is not known whether the observed MRC defects are pathogenic, compensatory responses, or secondary epiphenomena. In this perspective, we give an overview of current evidence for MRC dysfunction in PD, highlight pertinent knowledge gaps, and propose potential strategies for future research.
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Affiliation(s)
- Irene H. Flønes
- Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
- K.G Jebsen Center for Translational Research in Parkinson’s Disease, University of Bergen, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Charalampos Tzoulis
- Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
- K.G Jebsen Center for Translational Research in Parkinson’s Disease, University of Bergen, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
- *Correspondence: Charalampos Tzoulis,
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27
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Tönges L, Kwon EH, Klebe S. Monogenetic Forms of Parkinson’s Disease – Bridging the Gap Between Genetics and Biomarkers. Front Aging Neurosci 2022; 14:822949. [PMID: 35317530 PMCID: PMC8934414 DOI: 10.3389/fnagi.2022.822949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/08/2022] [Indexed: 11/13/2022] Open
Abstract
The therapy of neurodegenerative diseases such as Parkinson’s disease (PD) is still limited to the treatment of symptoms and primarily aimed at compensating for dopaminergic hypofunction. Numerous disease-modifying therapies currently in the pipeline attempt to modify the underlying pathomechanisms. In recent decades, the results of molecular genetics and biomarker research have raised hopes of earlier diagnosis and new neuroprotective therapeutic approaches. As the disease-causing processes in monogenetic forms of PD are better understood than in sporadic PD, these disease subsets are likely to benefit first from disease-modifying therapies. Recent studies have suggested that disease-relevant changes found in genetically linked forms of PD (i.e., PARK-LRRK2, PARK-GBA) can also be reproduced in patients in whom no genetic cause can be found, i.e., those with sporadic PD. It can, therefore, be assumed that as soon as the first causal therapy for genetic forms of PD is approved, more patients with PD will undergo genetic testing and counseling. Regarding future neuroprotective trials in neurodegenerative diseases and objective parameters such as biomarkers with high sensitivity and specificity for the diagnosis and course of the disease are needed. These biomarkers will also serve to monitor treatment success in clinical trials. Promising examples in PD, such as alpha-synuclein species, lysosomal enzymes, markers of amyloid and tau pathology, and neurofilament light chain, are under investigation in blood and CSF. This paper provides an overview of the opportunities and current limitations of monogenetic diagnostic and biomarker research in PD and aims to build a bridge between current knowledge and association with PD genetics and biomarkers.
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Affiliation(s)
- Lars Tönges
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany
- Center for Protein Diagnostics (ProDi), Ruhr University Bochum, Bochum, Germany
| | - Eun Hae Kwon
- Department of Neurology, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany
| | - Stephan Klebe
- Department of Neurology, University Hospital Essen, Essen, Germany
- *Correspondence: Stephan Klebe,
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28
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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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29
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α-Synuclein Overexpression Increases Dopamine D2/3 Receptor Binding and Immune Activation in a Model of Early Parkinson’s Disease. Biomedicines 2021; 9:biomedicines9121876. [PMID: 34944691 PMCID: PMC8698691 DOI: 10.3390/biomedicines9121876] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/01/2021] [Accepted: 12/07/2021] [Indexed: 12/14/2022] Open
Abstract
Progressive degeneration of dopaminergic neurons, immune activation, and α-synuclein pathology characterize Parkinson’s disease (PD). We previously reported that unilateral intranigral injection of recombinant adeno-associated viral (rAAV) vectors encoding wild-type human α-synuclein produced a rat model of early PD with dopamine terminal dysfunction. Here we tested the hypothesis that decreases in dopamine result in increased postsynaptic dopamine D2/D3 receptor expression, neuroinflammation, and reduced synaptic vesicle glycoprotein 2A (SV2A) density. Rats were injected with rAAV encoding α-synuclein or green fluorescent protein and subjected to non-pharmacological motor tests, before euthanization at 12 weeks post-injection. We performed: (1) in situ hybridization of nigral tyrosine hydroxylase mRNA, (2) HPLC of striatal dopamine content, and (3) autoradiography with [3H]raclopride, [3H]DTBZ, [3H]GBR12935, [3H]PK11195, and [3H]UCB-J to measure binding at D2/3 receptors, vesicular monoamine transporter 2, dopamine transporters, mitochondrial translocator protein, and SV2A, respectively. rAAV-α-synuclein induced motor asymmetry and reduced tyrosine hydroxylase mRNA and dopamine content in ipsilateral brain regions. This was paralleled by elevated ipsilateral postsynaptic dopamine D2/3 receptor expression and immune activation, with no changes to synaptic SV2A density. In conclusion, α-synuclein overexpression results in dopaminergic degeneration that induced compensatory increases in D2/3 binding and immune activation, recapitulating many of the pathological characteristics of PD.
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Raval NR, Gudmundsen F, Juhl M, Andersen IV, Speth N, Videbæk A, Petersen IN, Mikkelsen JD, Fisher PM, Herth MM, Plavén-Sigray P, Knudsen GM, Palner M. Synaptic Density and Neuronal Metabolic Function Measured by Positron Emission Tomography in the Unilateral 6-OHDA Rat Model of Parkinson's Disease. Front Synaptic Neurosci 2021; 13:715811. [PMID: 34867258 PMCID: PMC8636601 DOI: 10.3389/fnsyn.2021.715811] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 10/06/2021] [Indexed: 11/30/2022] Open
Abstract
Parkinson’s disease (PD) is caused by progressive neurodegeneration and characterised by motor dysfunction. Neurodegeneration of dopaminergic neurons also causes aberrations within the cortico-striato-thalamo-cortical (CSTC) circuit, which has been hypothesised to lead to non-motor symptoms such as depression. Individuals with PD have both lower synaptic density and changes in neuronal metabolic function in the basal ganglia, as measured using [11C]UCB-J and [18F]FDG positron emission tomography (PET), respectively. However, the two radioligands have not been directly compared in the same PD subject or in neurodegeneration animal models. Here, we investigate [11C]UCB-J binding and [18F]FDG uptake in the CSTC circuit following a unilateral dopaminergic lesion in rats and compare it to sham lesioned rats. Rats received either a unilateral injection of 6-hydroxydopamine (6-OHDA) or saline in the medial forebrain bundle and rostral substantia nigra (n = 4/group). After 3 weeks, all rats underwent two PET scans using [18F]FDG, followed by [11C]UCB-J on a separate day. [18F]FDG uptake and [11C]UCB-J binding were both lower in the ipsilateral striatal regions compared to the contralateral regions. Using [11C]UCB-J, we could detect an 8.7% decrease in the ipsilateral ventral midbrain, compared to a 2.9% decrease in ventral midbrain using [18F]FDG. Differential changes between hemispheres for [11C]UCB-J and [18F]FDG outcomes were also evident in the CSTC circuit’s cortical regions, especially in the orbitofrontal cortex and medial prefrontal cortex where higher synaptic density yet lower neuronal metabolic function was observed, following lesioning. In conclusion, [11C]UCB-J and [18F]FDG PET can detect divergent changes following a dopaminergic lesion in rats, especially in cortical regions that are not directly affected by the neurotoxin. These results suggest that combined [11C]UCB-J and [18F]FDG scans could yield a better picture of the heterogeneous cerebral changes in neurodegenerative disorders.
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Affiliation(s)
- Nakul Ravi Raval
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Frederik Gudmundsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Morten Juhl
- Cardiology Stem Cell Centre, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Ida Vang Andersen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nikolaj Speth
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Annesofie Videbæk
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Ida Nymann Petersen
- Department of Clinical Physiology, Nuclear Medicine & PET, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Jens D Mikkelsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark
| | | | - Matthias Manfred Herth
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Clinical Physiology, Nuclear Medicine & PET, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Pontus Plavén-Sigray
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Gitte Moos Knudsen
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mikael Palner
- Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Clinical Physiology and Nuclear Medicine, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Department of Nuclear Medicine, Odense University Hospital, Odense, Denmark
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31
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Binda KH, Lillethorup TP, Real CC, Bærentzen SL, Nielsen MN, Orlowski D, Brooks DJ, Chacur M, Landau AM. Exercise protects synaptic density in a rat model of Parkinson's disease. Exp Neurol 2021; 342:113741. [PMID: 33965411 DOI: 10.1016/j.expneurol.2021.113741] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/04/2021] [Indexed: 01/09/2023]
Abstract
BACKGROUND Parkinson's disease (PD) is characterized by Lewy body and neurite pathology associated with dopamine terminal dysfunction. Clinically, it is associated with motor slowing, rigidity, and tremor. Postural instability and pain are also features. Physical exercise benefits PD patients - possibly by promoting neuroplasticity including synaptic regeneration. OBJECTIVES In a parkinsonian rat model, we test the hypotheses that exercise: (a) increases synaptic density and reduces neuroinflammation and (b) lowers the nociceptive threshold by increasing μ-opioid receptor expression. METHODS Brain autoradiography was performed on rats unilaterally injected with either 6-hydroxydopamine (6-OHDA) or saline and subjected to treadmill exercise over 5 weeks. [3H]UCB-J was used to measure synaptic vesicle glycoprotein 2A (SV2A) density. Dopamine D2/3 receptor and μ-opioid receptor availability were assessed with [3H]Raclopride and [3H]DAMGO, respectively, while neuroinflammation was detected with the 18kDA translocator protein (TSPO) marker [3H]PK11195. The nociceptive threshold was determined prior to and throughout the exercise protocol. RESULTS We confirmed a dopaminegic deficit with increased striatal [3H]Raclopride D2/3 receptor availability and reduced nigral tyrosine hydroxylase immunoreactivity in the ipsilateral hemisphere of all 6-OHDA-injected rats. Sedentary rats lesioned with 6-OHDA showed significant reduction of ipsilateral striatal and substantia nigra [3H]UCB-J binding while [3H]PK11195 showed increased ipsilateral striatal neuroinflammation. Lesioned rats who exercised had higher levels of ipsilateral striatal [3H]UCB-J binding and lower levels of neuroinflammation compared to sedentary lesioned rats. Striatal 6-OHDA injections reduced thalamic μ-opioid receptor availability but subsequent exercise restored binding. Exercise also raised thalamic and hippocampal SV2A synaptic density in 6-OHDA lesioned rats, accompanied by a rise in nociceptive threshold. CONCLUSION These data suggest that treadmill exercise protects nigral and striatal synaptic integrity in a rat lesion model of PD - possibly by promoting compensatory mechanisms. Exercise was also associated with reduced neuroinflammation post lesioning and altered opioid transmission resulting in an increased nociceptive threshold.
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Affiliation(s)
- K H Binda
- Translational Neuropsychiatry Unit, Aarhus University, Universitetsbyen 13, Building 2b, Aarhus C 8000, Denmark; Department of Nuclear Medicine and PET, Aarhus University and Hospital, Palle Juul-Jensens Boulevard 165, J109, Aarhus N 8200, Denmark; Laboratory of Functional Neuroanatomy of Pain, Departamento de Anatomia, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
| | - T P Lillethorup
- Department of Nuclear Medicine and PET, Aarhus University and Hospital, Palle Juul-Jensens Boulevard 165, J109, Aarhus N 8200, Denmark.
| | - C C Real
- Translational Neuropsychiatry Unit, Aarhus University, Universitetsbyen 13, Building 2b, Aarhus C 8000, Denmark; Department of Nuclear Medicine and PET, Aarhus University and Hospital, Palle Juul-Jensens Boulevard 165, J109, Aarhus N 8200, Denmark; Laboratory of Nuclear Medicine (LIM 43), Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
| | - S L Bærentzen
- Translational Neuropsychiatry Unit, Aarhus University, Universitetsbyen 13, Building 2b, Aarhus C 8000, Denmark; Department of Nuclear Medicine and PET, Aarhus University and Hospital, Palle Juul-Jensens Boulevard 165, J109, Aarhus N 8200, Denmark.
| | - M N Nielsen
- Translational Neuropsychiatry Unit, Aarhus University, Universitetsbyen 13, Building 2b, Aarhus C 8000, Denmark.
| | - D Orlowski
- Center for Experimental Neuroscience (CENSE), Department of Clinical Medicine, Aarhus University and Department of Neurosurgery, Aarhus University Hospital, Aarhus N, 8200, Denmark.
| | - D J Brooks
- Department of Nuclear Medicine and PET, Aarhus University and Hospital, Palle Juul-Jensens Boulevard 165, J109, Aarhus N 8200, Denmark; Institute for Translational and Clinical Research, Newcastle University, Newcastle upon Tyne NE4 5PL, UK.
| | - M Chacur
- Laboratory of Functional Neuroanatomy of Pain, Departamento de Anatomia, Universidade de Sao Paulo, Sao Paulo, SP, Brazil.
| | - A M Landau
- Translational Neuropsychiatry Unit, Aarhus University, Universitetsbyen 13, Building 2b, Aarhus C 8000, Denmark; Department of Nuclear Medicine and PET, Aarhus University and Hospital, Palle Juul-Jensens Boulevard 165, J109, Aarhus N 8200, Denmark.
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Halff EF, Cotel MC, Natesan S, McQuade R, Ottley CJ, Srivastava DP, Howes OD, Vernon AC. Effects of chronic exposure to haloperidol, olanzapine or lithium on SV2A and NLGN synaptic puncta in the rat frontal cortex. Behav Brain Res 2021; 405:113203. [PMID: 33636238 DOI: 10.1016/j.bbr.2021.113203] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/16/2021] [Accepted: 02/17/2021] [Indexed: 01/03/2023]
Abstract
Positron emission tomography studies using the synaptic vesicle glycoprotein 2A (SV2A) radioligand [11C]-UCB-J provide in vivo evidence for synaptic dysfunction and/or loss in the cingulate and frontal cortex of patients with schizophrenia. In exploring potential confounding effects of antipsychotic medication, we previously demonstrated that chronic (28-day) exposure to clinically relevant doses of haloperidol does not affect [3H]-UCB-J radioligand binding in the cingulate and frontal cortex of male rats. Furthermore, neither chronic haloperidol nor olanzapine exposure had any effect on SV2A protein levels in these brain regions. These data do not exclude the possibility, however, that more subtle changes in SV2A may occur at pre-synaptic terminals, or the post-synaptic density, following chronic antipsychotic drug exposure. Moreover, relatively little is known about the potential effects of psychotropic drugs other than antipsychotics on SV2A. To address these questions directly, we herein used immunostaining and confocal microscopy to explore the effect of chronic (28-day) exposure to clinically relevant doses of haloperidol, olanzapine or the mood stabilizer lithium on presynaptic SV2A, postsynaptic Neuroligin (NLGN) puncta and their overlap as a measure of total synaptic density in the rat prefrontal and anterior cingulate cortex. We found that, under the conditions tested here, exposure to antipsychotics had no effect on SV2A, NLGN, or overall synaptic puncta count. In contrast, chronic lithium exposure significantly increased NLGN puncta density relative to vehicle, with no effect on either SV2A or total synaptic puncta. Future studies are required to understand the functional consequences of these changes.
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Affiliation(s)
- Els F Halff
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK; Psychiatric Imaging group, MRC London Institute of Medical Sciences, Du Cane Road, London W12 0NN, UK
| | - Marie-Caroline Cotel
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, 5 Cutcombe Road, London SE5 9RT, UK
| | - Sridhar Natesan
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK; Psychiatric Imaging group, MRC London Institute of Medical Sciences, Du Cane Road, London W12 0NN, UK; Psychiatric Imaging group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital, 72 Du Cane Road, London W12 0HS, UK
| | - Richard McQuade
- Psychobiology Research Group, School of Neurology, Neurobiology and Psychiatry, Newcastle University, NE2 4HH, Newcastle upon Tyne, UK
| | - Chris J Ottley
- Department of Earth Sciences, Durham University, Durham, DH1 3LE, UK
| | - Deepak P Srivastava
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, 5 Cutcombe Road, London SE5 9RT, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK
| | - Oliver D Howes
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London, SE5 8AF, UK; Psychiatric Imaging group, MRC London Institute of Medical Sciences, Du Cane Road, London W12 0NN, UK; Psychiatric Imaging group, Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, Hammersmith Hospital, 72 Du Cane Road, London W12 0HS, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK; South London and Maudsley NHS Foundation Trust, Camberwell, London, UK
| | - Anthony C Vernon
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, 5 Cutcombe Road, London SE5 9RT, UK; MRC Centre for Neurodevelopmental Disorders, King's College London, London SE1 1UL, UK.
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Andersen KB, Hansen AK, Damholdt MF, Horsager J, Skjaerbaek C, Gottrup H, Klit H, Schacht AC, Danielsen EH, Brooks DJ, Borghammer P. Reduced Synaptic Density in Patients with Lewy Body Dementia: An [ 11 C]UCB-J PET Imaging Study. Mov Disord 2021; 36:2057-2065. [PMID: 33899255 DOI: 10.1002/mds.28617] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/23/2021] [Accepted: 03/24/2021] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Patients with Parkinson's disease (PD) often develop dementia, but the underlying substrate is incompletely understood. Generalized synaptic degeneration may contribute to dysfunction and cognitive decline in Lewy body dementias, but in vivo evidence is lacking. OBJECTIVE The objective of this study was to assess the density of synapses in non-demented PD (nPD) subjects (N = 21), patients with PD-dementia or Dementia with Lewy bodies (DLB) (N = 13), and age-matched healthy controls (N = 15). METHOD Using in vivo PET imaging and the novel synaptic-vesicle-glycoprotein 2A (SV2A) radioligand [11C]UCB-J, SUVR-1 values were obtained for 12 pre-defined regions. Volumes-of-interest were defined on MRI T1 scans. Voxel-level between-group comparisons of [11C]UCB-J SUVR-1 were performed. All subjects underwent neuropsychological assessment. Correlations between [11C]UCB- J PET and domain-specific cognitive functioning were examined. RESULTS nPD patients only demonstrated significantly reduced SUVR-1 values in the substantia nigra (SN) compared to HC. DLB/PDD patients demonstrated reduced SUVR-1 values in SN and all cortical VOIs except for the hippocampus and amygdala. The voxel-based analysis supported the VOI results. Significant correlation was seen between middle frontal gyrus [11C]UCB-J SUVR-1 and performance on tests of executive function. CONCLUSION Widespread cortical reduction of synaptic density was documented in a cohort of DLB/PDD subjects using in vivo [11C]UCB-J PET. Our study confirms previously reported synaptic loss in SN of nPD patients. [11C]UCB-J binding in selected cortical VOIs of the DLB/PDD patients correlated with their levels of cognitive function across relevant neuropsychological domains. These findings suggest that the loss of synaptic density contributes to cognitive impairment in nPD and DLB/PDD. © 2021 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Katrine B Andersen
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark
| | - Allan K Hansen
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark
| | - Malene F Damholdt
- Department of Psychology and Behavioural Science, Aarhus University, Aarhus, Denmark
| | - Jacob Horsager
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark
| | - Casper Skjaerbaek
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark
| | - Hanne Gottrup
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | - Henriette Klit
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Erik H Danielsen
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | - David J Brooks
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark.,Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, UK.,Department of Brain Sciences, Imperial College London, London, UK
| | - Per Borghammer
- Department of Nuclear Medicine and PET, Aarhus University Hospital, Aarhus, Denmark
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Prasuhn J, Brüggemann N. Genotype-driven therapeutic developments in Parkinson's disease. Mol Med 2021; 27:42. [PMID: 33874883 PMCID: PMC8056568 DOI: 10.1186/s10020-021-00281-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 02/12/2021] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Remarkable advances have been reached in the understanding of the genetic basis of Parkinson's disease (PD), with the identification of monogenic causes (mPD) and a plethora of gene loci leading to an increased risk for idiopathic PD. The expanding knowledge and subsequent identification of genetic contributions fosters the understanding of molecular mechanisms leading to disease development and progression. Distinct pathways involved in mitochondrial dysfunction, oxidative stress, and lysosomal function have been identified and open a unique window of opportunity for individualized treatment approaches. These genetic findings have led to an imminent progress towards pathophysiology-targeted clinical trials and potentially disease-modifying treatments in the future. MAIN BODY OF THE MANUSCRIPT In this review article we will summarize known genetic contributors to the pathophysiology of Parkinson's disease, the molecular mechanisms leading to disease development, and discuss challenges and opportunities in clinical trial designs. CONCLUSIONS The future success of clinical trials in PD is mainly dependent on reliable biomarker development and extensive genetic testing to identify genetic cases. Whether genotype-dependent stratification of study participants will extend the potential application of new drugs will be one major challenge in conceptualizing clinical trials. However, the latest developments in genotype-driven treatments will pave the road to individualized pathophysiology-based therapies in the future.
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Affiliation(s)
- Jannik Prasuhn
- Department of Neurology, University Medical Center Schleswig-Holstein, Campus Lübeck, Lübeck, Germany
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
- Center of Brain, Behavior and Metabolism, University of Lübeck, Lübeck, Germany
| | - Norbert Brüggemann
- Department of Neurology, University Medical Center Schleswig-Holstein, Campus Lübeck, Lübeck, Germany.
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany.
- Center of Brain, Behavior and Metabolism, University of Lübeck, Lübeck, Germany.
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Prasuhn J, Davis RL, Kumar KR. Targeting Mitochondrial Impairment in Parkinson's Disease: Challenges and Opportunities. Front Cell Dev Biol 2021; 8:615461. [PMID: 33469539 PMCID: PMC7813753 DOI: 10.3389/fcell.2020.615461] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 12/07/2020] [Indexed: 12/12/2022] Open
Abstract
The underlying pathophysiology of Parkinson's disease is complex, but mitochondrial dysfunction has an established and prominent role. This is supported by an already large and rapidly growing body of evidence showing that the role of mitochondrial (dys)function is central and multifaceted. However, there are clear gaps in knowledge, including the dilemma of explaining why inherited mitochondriopathies do not usually present with parkinsonian symptoms. Many aspects of mitochondrial function are potential therapeutic targets, including reactive oxygen species production, mitophagy, mitochondrial biogenesis, mitochondrial dynamics and trafficking, mitochondrial metal ion homeostasis, sirtuins, and endoplasmic reticulum links with mitochondria. Potential therapeutic strategies may also incorporate exercise, microRNAs, mitochondrial transplantation, stem cell therapies, and photobiomodulation. Despite multiple studies adopting numerous treatment strategies, clinical trials to date have generally failed to show benefit. To overcome this hurdle, more accurate biomarkers of mitochondrial dysfunction are required to detect subtle beneficial effects. Furthermore, selecting study participants early in the disease course, studying them for suitable durations, and stratifying them according to genetic and neuroimaging findings may increase the likelihood of successful clinical trials. Moreover, treatments involving combined approaches will likely better address the complexity of mitochondrial dysfunction in Parkinson's disease. Therefore, selecting the right patients, at the right time, and using targeted combination treatments, may offer the best chance for development of an effective novel therapy targeting mitochondrial dysfunction in Parkinson's disease.
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Affiliation(s)
- Jannik Prasuhn
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany.,Department of Neurology, University Medical Center Schleswig-Holstein, Lübeck, Germany.,Center for Brain, Behavior, and Metabolism, University of Lübeck, Lübeck, Germany
| | - Ryan L Davis
- Department of Neurogenetics, Kolling Institute, University of Sydney and Northern Sydney Local Health District, Sydney, NSW, Australia.,Department of Neurogenetics, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Kishore R Kumar
- Molecular Medicine Laboratory and Department of Neurology, Concord Repatriation General Hospital, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia.,Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Darlinghurst, NSW, Australia
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36
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Clark EH, Vázquez de la Torre A, Hoshikawa T, Briston T. Targeting mitophagy in Parkinson's disease. J Biol Chem 2021; 296:100209. [PMID: 33372898 PMCID: PMC7948953 DOI: 10.1074/jbc.rev120.014294] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 12/18/2020] [Accepted: 12/18/2020] [Indexed: 12/22/2022] Open
Abstract
The genetics and pathophysiology of Parkinson's disease (PD) strongly implicate mitochondria in disease aetiology. Elegant studies over the last two decades have elucidated complex molecular signaling governing the identification and removal of dysfunctional mitochondria from the cell, a process of mitochondrial quality control known as mitophagy. Mitochondrial deficits and specifically reduced mitophagy are evident in both sporadic and familial PD. Mendelian genetics attributes loss-of-function mutations in key mitophagy regulators PINK1 and Parkin to early-onset PD. Pharmacologically enhancing mitophagy and accelerating the removal of damaged mitochondria are of interest for developing a disease-modifying PD therapeutic. However, despite significant understanding of both PINK1-Parkin-dependent and -independent mitochondrial quality control pathways, the therapeutic potential of targeting mitophagy remains to be fully explored. Here, we provide a summary of the genetic evidence supporting the role for mitophagy failure as a pathogenic mechanism in PD. We assess the tractability of mitophagy pathways and prospects for drug discovery and consider intervention points for mitophagy enhancement. We explore the numerous hit molecules beginning to emerge from high-content/high-throughput screening as well as the biochemical and phenotypic assays that enabled these screens. The chemical and biological properties of these reference compounds suggest many could be used to interrogate and perturb mitochondrial biology to validate promising drug targets. Finally, we address key considerations and challenges in achieving preclinical proof-of-concept, including in vivo mitophagy reporter methodologies and disease models, as well as patient stratification and biomarker development for mitochondrial forms of the disease.
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Affiliation(s)
- Emily H Clark
- Hatfield Research Laboratories, Neurology Innovation Centre, Eisai Ltd, Hatfield, United Kingdom
| | | | - Tamaki Hoshikawa
- Hatfield Research Laboratories, Neurology Innovation Centre, Eisai Ltd, Hatfield, United Kingdom
| | - Thomas Briston
- Hatfield Research Laboratories, Neurology Innovation Centre, Eisai Ltd, Hatfield, United Kingdom.
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Thomsen MB, Ferreira SA, Schacht AC, Jacobsen J, Simonsen M, Betzer C, Jensen PH, Brooks DJ, Landau AM, Romero-Ramos M. PET imaging reveals early and progressive dopaminergic deficits after intra-striatal injection of preformed alpha-synuclein fibrils in rats. Neurobiol Dis 2020; 149:105229. [PMID: 33352233 DOI: 10.1016/j.nbd.2020.105229] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 12/16/2020] [Accepted: 12/17/2020] [Indexed: 12/24/2022] Open
Abstract
Alpha-synuclein (a-syn) can aggregate and form toxic oligomers and insoluble fibrils which are the main component of Lewy bodies. Intra-neuronal Lewy bodies are a major pathological characteristic of Parkinson's disease (PD). These fibrillar structures can act as seeds and accelerate the aggregation of monomeric a-syn. Indeed, recent studies show that injection of preformed a-syn fibrils (PFF) into the rodent brain can induce aggregation of the endogenous monomeric a-syn resulting in neuronal dysfunction and eventual cell death. We injected 8 μg of murine a-syn PFF, or soluble monomeric a-syn into the right striatum of rats. The animals were monitored behaviourally using the cylinder test, which measures paw asymmetry, and the corridor task that measures lateralized sensorimotor response to sugar treats. In vivo PET imaging was performed after 6, 13 and 22 weeks using [11C]DTBZ, a marker of the vesicular monoamine 2 transporter (VMAT2), and after 15 and 22 weeks using [11C]UCB-J, a marker of synaptic SV2A protein in nerve terminals. Histology was performed at the three time points using antibodies against dopaminergic markers, aggregated a-syn, and MHCII to evaluate the immune response. While the a-syn PFF injection caused only mild behavioural changes, [11C]DTBZ PET showed a significant and progressive decrease of VMAT2 binding in the ipsilateral striatum. This was accompanied by a small progressive decrease in [11C]UCB-J binding in the same area. In addition, our histological analysis revealed a gradual spread of misfolded a-syn pathology in areas anatomically connected to striatum that became bilateral with time. The striatal a-syn PFF injection resulted in a progressive unilateral degeneration of dopamine terminals, and an early and sustained presence of MHCII positive ramified microglia in the ipsilateral striatum and substantia nigra. Our study shows that striatal injections of a-syn fibrils induce progressive pathological synaptic dysfunction prior to cell death that can be detected in vivo with PET. We confirm that intrastriatal injection of a-syn PFFs provides a model of progressive a-syn pathology with loss of dopaminergic and synaptic function accompanied by neuroinflammation, as found in human PD.
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Affiliation(s)
- Majken B Thomsen
- Department of Nuclear Medicine and PET Center, Institute of Clinical Medicine, Aarhus University and Hospital, Aarhus, Denmark; Department of Biomedicine, Aarhus University, Aarhus, Denmark; Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus, Denmark
| | - Sara A Ferreira
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus, Denmark
| | - Anna C Schacht
- Department of Nuclear Medicine and PET Center, Institute of Clinical Medicine, Aarhus University and Hospital, Aarhus, Denmark
| | - Jan Jacobsen
- Department of Nuclear Medicine and PET Center, Institute of Clinical Medicine, Aarhus University and Hospital, Aarhus, Denmark
| | - Mette Simonsen
- Department of Nuclear Medicine and PET Center, Institute of Clinical Medicine, Aarhus University and Hospital, Aarhus, Denmark
| | - Cristine Betzer
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus, Denmark
| | - Poul H Jensen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus, Denmark
| | - David J Brooks
- Department of Nuclear Medicine and PET Center, Institute of Clinical Medicine, Aarhus University and Hospital, Aarhus, Denmark; Newcastle University Translational and Clinical Research Institute, Newcastle upon Tyne, UK
| | - Anne M Landau
- Department of Nuclear Medicine and PET Center, Institute of Clinical Medicine, Aarhus University and Hospital, Aarhus, Denmark; Translational Neuropsychiatry Unit, Institute of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Marina Romero-Ramos
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Danish Research Institute of Translational Neuroscience - DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, Aarhus University, Aarhus, Denmark.
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Novel PET Biomarkers to Disentangle Molecular Pathways across Age-Related Neurodegenerative Diseases. Cells 2020; 9:cells9122581. [PMID: 33276490 PMCID: PMC7761606 DOI: 10.3390/cells9122581] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/25/2020] [Accepted: 11/28/2020] [Indexed: 12/11/2022] Open
Abstract
There is a need to disentangle the etiological puzzle of age-related neurodegenerative diseases, whose clinical phenotypes arise from known, and as yet unknown, pathways that can act distinctly or in concert. Enhanced sub-phenotyping and the identification of in vivo biomarker-driven signature profiles could improve the stratification of patients into clinical trials and, potentially, help to drive the treatment landscape towards the precision medicine paradigm. The rapidly growing field of neuroimaging offers valuable tools to investigate disease pathophysiology and molecular pathways in humans, with the potential to capture the whole disease course starting from preclinical stages. Positron emission tomography (PET) combines the advantages of a versatile imaging technique with the ability to quantify, to nanomolar sensitivity, molecular targets in vivo. This review will discuss current research and available imaging biomarkers evaluating dysregulation of the main molecular pathways across age-related neurodegenerative diseases. The molecular pathways focused on in this review involve mitochondrial dysfunction and energy dysregulation; neuroinflammation; protein misfolding; aggregation and the concepts of pathobiology, synaptic dysfunction, neurotransmitter dysregulation and dysfunction of the glymphatic system. The use of PET imaging to dissect these molecular pathways and the potential to aid sub-phenotyping will be discussed, with a focus on novel PET biomarkers.
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Shirokova OM, Pchelin PV, Mukhina IV. MERCs. The Novel Assistant to Neurotransmission? Front Neurosci 2020; 14:589319. [PMID: 33240039 PMCID: PMC7680918 DOI: 10.3389/fnins.2020.589319] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 10/19/2020] [Indexed: 12/11/2022] Open
Abstract
In neuroscience, much attention is paid to intercellular interactions, in particular, to synapses. However, many researchers do not pay due attention to the contribution of intracellular contacts to the work of intercellular interactions. Nevertheless, along with synapses, intracellular contacts also have complex organization and a tremendous number of regulatory elements. Mitochondria-endoplasmic reticulum contacts (MERCs) are a specific site of interaction between the two organelles; they provide a basis for a large number of cellular functions, such as calcium homeostasis, lipid metabolism, autophagy, and apoptosis. Despite the presence of these contacts in various parts of neurons and glial cells, it is yet not known whether they fulfill the same functions. There are still many unsolved questions about the work of these intracellular contacts, and one of the most important among them is if MERCs, with their broad implication into synaptic events, can be considered the assistant to neurotransmission?
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Affiliation(s)
- Olesya M Shirokova
- Central Scientific Research Laboratory, Institute of Fundamental Medicine, Privolzhsky Research Medical University, Nizhny Novgorod, Russia
| | - Pavel V Pchelin
- Central Scientific Research Laboratory, Institute of Fundamental Medicine, Privolzhsky Research Medical University, Nizhny Novgorod, Russia.,Department of Neurotechnology, Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - Irina V Mukhina
- Central Scientific Research Laboratory, Institute of Fundamental Medicine, Privolzhsky Research Medical University, Nizhny Novgorod, Russia.,Department of Neurotechnology, Institute of Biology and Biomedicine, Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
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