1
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Chauveau F, Winkeler A, Chalon S, Boutin H, Becker G. PET imaging of neuroinflammation: any credible alternatives to TSPO yet? Mol Psychiatry 2024:10.1038/s41380-024-02656-9. [PMID: 38997465 DOI: 10.1038/s41380-024-02656-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 06/26/2024] [Accepted: 07/01/2024] [Indexed: 07/14/2024]
Abstract
Over the last decades, the role of neuroinflammation in neuropsychiatric conditions has attracted an exponentially growing interest. A key driver for this trend was the ability to image brain inflammation in vivo using PET radioligands targeting the Translocator Protein 18 kDa (TSPO), which is known to be expressed in activated microglia and astrocytes upon inflammatory events as well as constitutively in endothelial cells. TSPO is a mitochondrial protein that is expressed mostly by microglial cells upon activation but is also expressed by astrocytes in some conditions and constitutively by endothelial cells. Therefore, our current understanding of neuroinflammation dynamics is hampered by the lack of alternative targets available for PET imaging. We performed a systematic search and review on radiotracers developed for neuroinflammation PET imaging apart from TSPO. The following targets of interest were identified through literature screening (including previous narrative reviews): P2Y12R, P2X7R, CSF1R, COX (microglial targets), MAO-B, I2BS (astrocytic targets), CB2R & S1PRs (not specific of a single cell type). We determined the level of development and provided a scoping review for each target. Strikingly, astrocytic biomarker MAO-B has progressed in clinical investigations the furthest, while few radiotracers (notably targeting S1P1Rs, CSF1R) are being implemented in clinical investigations. Other targets such as CB2R and P2X7R have proven disappointing in clinical studies (e.g. poor signal, lack of changes in disease conditions, etc.). While astrocytic targets are promising, development of new biomarkers and tracers specific for microglial activation has proven challenging.
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Affiliation(s)
- Fabien Chauveau
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
| | - Alexandra Winkeler
- Université Paris-Saclay, Inserm, CNRS, CEA, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401, Orsay, France
| | - Sylvie Chalon
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France
| | - Hervé Boutin
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France.
| | - Guillaume Becker
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
- Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail, 14 rue Pierre et Marie Curie, 94701, Maisons-Alfort, Cedex, France
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2
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Fontana IC, Kumar A, Okamura N, Nordberg A. Multitracer Approach to Understanding the Complexity of Reactive Astrogliosis in Alzheimer's Brains. ACS Chem Neurosci 2024; 15:328-336. [PMID: 38133820 PMCID: PMC10797624 DOI: 10.1021/acschemneuro.3c00646] [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: 10/07/2023] [Revised: 11/28/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023] Open
Abstract
A monoamine oxidase B (MAO-B) selective positron emission tomography (PET) tracer [11C]-deuterium-l-deprenyl holds promise for imaging reactive astrogliosis in neurodegenerative diseases, such as Alzheimer's disease (AD). Two novel PET tracers ([11C]-BU99008 and [18F]-SMBT-1) have recently been developed to assess the complexity of reactive astrogliosis in the AD continuum. We have investigated the binding properties of SMBT-1, l-deprenyl, and BU99008 in AD and cognitively normal control (CN) brains. Competition binding assays with [3H]-l-deprenyl and [3H]-BU99008 versus unlabeled SMBT-1 in postmortem AD and CN temporal and frontal cortex brains demonstrated that SMBT-1 interacted with [3H]-deprenyl at a single binding site (nM range) and with [3H]-BU99008 at multiple binding sites (from nM to μM). Autoradiography studies on large frozen postmortem AD and CN hemisphere brain sections demonstrated that 1 μM SMBT-1 almost completely displaced the [3H]-l-deprenyl binding (>90%), while SMBT-1 only partly displaced the [3H]-BU99008 binding (50-60% displacement) in cortical regions. In conclusion, SMBT-1, l-deprenyl, and BU99008 interact at the same MAO-B binding site, while BU99008 shows an additional independent binding site in AD and CN brains. The high translational power of our studies in human AD and CN brains suggests that the multitracer approach with SMBT-1, l-deprenyl, and BU99008 could be useful for imaging reactive astrogliosis.
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Affiliation(s)
- Igor C. Fontana
- Division
of Clinical Geriatrics, Center for Alzheimer Research, Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, S-141 83 Stockholm, Sweden
| | - Amit Kumar
- Division
of Clinical Geriatrics, Center for Alzheimer Research, Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, S-141 83 Stockholm, Sweden
| | - Nobuyuki Okamura
- Department
of Pharmacology, Tohoku Medical and Pharmaceutical
University, Sendai 983-8536, Japan
| | - Agneta Nordberg
- Division
of Clinical Geriatrics, Center for Alzheimer Research, Department
of Neurobiology, Care Sciences and Society, Karolinska Institutet, S-141 83 Stockholm, Sweden
- Theme
Inflammation and Aging, Karolinska University
Hospital, S-141 57 Stockholm, Sweden
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3
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Fontana IC, Scarpa M, Malarte ML, Rocha FM, Ausellé-Bosch S, Bluma M, Bucci M, Chiotis K, Kumar A, Nordberg A. Astrocyte Signature in Alzheimer's Disease Continuum through a Multi-PET Tracer Imaging Perspective. Cells 2023; 12:1469. [PMID: 37296589 PMCID: PMC10253101 DOI: 10.3390/cells12111469] [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: 02/01/2023] [Revised: 05/02/2023] [Accepted: 05/19/2023] [Indexed: 06/12/2023] Open
Abstract
Reactive astrogliosis is an early event in the continuum of Alzheimer's disease (AD). Current advances in positron emission tomography (PET) imaging provide ways of assessing reactive astrogliosis in the living brain. In this review, we revisit clinical PET imaging and in vitro findings using the multi-tracer approach, and point out that reactive astrogliosis precedes the deposition of Aβ plaques, tau pathology, and neurodegeneration in AD. Furthermore, considering the current view of reactive astrogliosis heterogeneity-more than one subtype of astrocyte involved-in AD, we discuss how astrocytic body fluid biomarkers might fit into trajectories different from that of astrocytic PET imaging. Future research focusing on the development of innovative astrocytic PET radiotracers and fluid biomarkers may provide further insights into the heterogeneity of reactive astrogliosis and improve the detection of AD in its early stages.
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Affiliation(s)
- Igor C. Fontana
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Miriam Scarpa
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Mona-Lisa Malarte
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Filipa M. Rocha
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
- Instituto de Ciência Biomédicas Abel Salazar da Universidade do Porto, 4050-313 Porto, Portugal
- Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto, Portugal
| | - Sira Ausellé-Bosch
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
- Faculty of Health and Life Sciences, Pompeu Fabra University, 08003 Barcelona, Spain
| | - Marina Bluma
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Marco Bucci
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Konstantinos Chiotis
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Amit Kumar
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
| | - Agneta Nordberg
- Division of Clinical Geriatrics, Center for Alzheimer Research, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 141 52 Stockholm, Sweden
- Theme Inflammation and Aging, Karolinska University Hospital, 141 57 Stockholm, Sweden
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4
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Raval NR, Wetherill RR, Wiers CE, Dubroff JG, Hillmer AT. Positron Emission Tomography of Neuroimmune Responses in Humans: Insights and Intricacies. Semin Nucl Med 2023; 53:213-229. [PMID: 36270830 PMCID: PMC11261531 DOI: 10.1053/j.semnuclmed.2022.08.008] [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: 08/15/2022] [Accepted: 08/30/2022] [Indexed: 11/06/2022]
Abstract
The brain's immune system plays a critical role in responding to immune challenges and maintaining homeostasis. However, dysregulated neuroimmune function contributes to neurodegenerative disease and neuropsychiatric conditions. In vivo positron emission tomography (PET) imaging of the neuroimmune system has facilitated a greater understanding of its physiology and the pathology of some neuropsychiatric conditions. This review presents an in-depth look at PET findings from human neuroimmune function studies, highlighting their importance in current neuropsychiatric research. Although the majority of human PET studies feature radiotracers targeting the translocator protein 18 kDa (TSPO), this review also considers studies with other neuroimmune targets, including monoamine oxidase B, cyclooxygenase-1 and cyclooxygenase-2, nitric oxide synthase, and the purinergic P2X7 receptor. Promising new targets, such as colony-stimulating factor 1, Sphingosine-1-phosphate receptor 1, and the purinergic P2Y12 receptor, are also discussed. The significance of validating neuroimmune targets and understanding their function and expression is emphasized in this review to better identify and interpret PET results.
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Affiliation(s)
- Nakul R Raval
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; Yale PET Center, Yale University, New Haven, CT
| | - Reagan R Wetherill
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Corinde E Wiers
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA; Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Jacob G Dubroff
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Ansel T Hillmer
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT; Yale PET Center, Yale University, New Haven, CT; Department of Psychiatry, Yale University, New Haven, CT.
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5
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Vezzani A, Ravizza T, Bedner P, Aronica E, Steinhäuser C, Boison D. Astrocytes in the initiation and progression of epilepsy. Nat Rev Neurol 2022; 18:707-722. [PMID: 36280704 PMCID: PMC10368155 DOI: 10.1038/s41582-022-00727-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2022] [Indexed: 11/09/2022]
Abstract
Epilepsy affects ~65 million people worldwide. First-line treatment options include >20 antiseizure medications, but seizure control is not achieved in approximately one-third of patients. Antiseizure medications act primarily on neurons and can provide symptomatic control of seizures, but do not alter the onset and progression of epilepsy and can cause serious adverse effects. Therefore, medications with new cellular and molecular targets and mechanisms of action are needed. Accumulating evidence indicates that astrocytes are crucial to the pathophysiological mechanisms of epilepsy, raising the possibility that these cells could be novel therapeutic targets. In this Review, we discuss how dysregulation of key astrocyte functions - gliotransmission, cell metabolism and immune function - contribute to the development and progression of hyperexcitability in epilepsy. We consider strategies to mitigate astrocyte dysfunction in each of these areas, and provide an overview of how astrocyte activation states can be monitored in vivo not only to assess their contribution to disease but also to identify markers of disease processes and treatment effects. Improved understanding of the roles of astrocytes in epilepsy has the potential to lead to novel therapies to prevent the initiation and progression of epilepsy.
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Affiliation(s)
- Annamaria Vezzani
- Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy.
| | - Teresa Ravizza
- Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy
| | - Peter Bedner
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Eleonora Aronica
- Amsterdam UMC, University of Amsterdam, Department of (Neuro)Pathology, Amsterdam Neuroscience, Amsterdam, Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, Netherlands
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Detlev Boison
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, USA
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6
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Zhao J, Wang C, Sun W, Li C. Tailoring Materials for Epilepsy Imaging: From Biomarkers to Imaging Probes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2203667. [PMID: 35735191 DOI: 10.1002/adma.202203667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Revised: 06/11/2022] [Indexed: 06/15/2023]
Abstract
Excising epileptic foci (EF) is the most efficient approach for treating drug-resistant epilepsy (DRE). However, owing to the vast heterogeneity of epilepsies, EF in one-third of patients cannot be accurately located, even after exhausting all current diagnostic strategies. Therefore, identifying biomarkers that truly represent the status of epilepsy and fabricating probes with high targeting specificity are prerequisites for identifying the "concealed" EF. However, no systematic summary of this topic has been published. Herein, the potential biomarkers of EF are first summarized and classified into three categories: functional, molecular, and structural aberrances during epileptogenesis, a procedure of nonepileptic brain biasing toward epileptic tissue. The materials used to fabricate these imaging probes and their performance in defining the EF in preclinical and clinical studies are highlighted. Finally, perspectives for developing the next generation of probes and their challenges in clinical translation are discussed. In general, this review can be helpful in guiding the development of imaging probes defining EF with improved accuracy and holds promise for increasing the number of DRE patients who are eligible for surgical intervention.
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Affiliation(s)
- Jing Zhao
- Key Laboratory of Smart Drug Delivery, Ministry of Education, School of Pharmacy, Fudan University, Zhangheng Road 826, Shanghai, 201203, China
| | - Cong Wang
- Key Laboratory of Smart Drug Delivery, Ministry of Education, School of Pharmacy, Fudan University, Zhangheng Road 826, Shanghai, 201203, China
- Academy for Engineering and Technology, Fudan University, 20 Handan Road, Yangpu District, Shanghai, 200433, China
- Shanghai Center for Brain Science and Brain-Inspired Technology, Shanghai, 200031, China
| | - Wanbing Sun
- Department of Neurology and Research Center of Neurology in Second Affiliated Hospital and Key Laboratory of Medical Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Cong Li
- Key Laboratory of Smart Drug Delivery, Ministry of Education, School of Pharmacy, Fudan University, Zhangheng Road 826, Shanghai, 201203, China
- State Key Laboratory of Medical Neurobiology, School of Pharmacy, Fudan University, Shanghai, 201203, China
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7
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Mohamed MA, Zeng Z, Gennaro M, Lao-Kaim NP, Myers JFM, Calsolaro V, Femminella GD, Tyacke RJ, Martin-Bastida A, Gunn RN, Nutt DJ, Edison P, Piccini P, Roussakis AA. Astrogliosis in aging and Parkinson’s disease dementia: a new clinical study with 11C-BU99008 PET. Brain Commun 2022; 4:fcac199. [PMID: 36072646 PMCID: PMC9445175 DOI: 10.1093/braincomms/fcac199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 05/20/2022] [Accepted: 08/16/2022] [Indexed: 11/14/2022] Open
Abstract
The role of astrogliosis in the pathology of brain aging and neurodegenerative diseases has recently drawn great attention. Imidazoline-2 binding sites represent a possible target to map the distribution of reactive astrocytes. In this study, we use 11C-BU99008, an imidazoline-2 binding sites-specific PET radioligand, to image reactive astrocytes in vivo in healthy controls and patients with established Parkinson’s disease dementia. Eighteen healthy controls (age: 45–78 years) and six patients with Parkinson’s disease dementia (age: 64–77 years) had one 11C-BU99008 PET-CT scan with arterial input function. All subjects underwent one 3 T MRI brain scan to facilitate the analysis of the PET data and to capture individual cerebral atrophy. Regional 11C-BU99008 volumes of distribution were calculated for each subject by the two-tissue compartmental modelling. Positive correlations between 11C-BU99008 volumes of distribution values and age were found for all tested regions across the brain within healthy controls (P < 0.05); furthermore, multiple regression indicated that aging affects 11C-BU99008 volumes of distribution values in a region-specific manner. Independent samples t-test indicated that there was no significant group difference in 11C-BU99008 volumes of distribution values between Parkinson’s disease dementia (n = 6; mean age = 71.97 ± 4.66 years) and older healthy controls (n = 9; mean age = 71.90 ± 5.51 years). Our data set shows that astrogliosis is common with aging in a region-specific manner. However, in this set-up, 11C-BU99008 PET cannot differentiate patients with Parkinson’s disease dementia from healthy controls of similar age.
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Affiliation(s)
- Mohamed A Mohamed
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
| | - Zhou Zeng
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
- Xiangya Hospital of Central South University , Changsha, Hunan , P.R. China
| | - Marta Gennaro
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
| | - Nicholas P Lao-Kaim
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
| | - Jim F M Myers
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
| | - Valeria Calsolaro
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
| | - Grazia Daniela Femminella
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
- Department of Translational Medical Sciences, University of Naples Federico II , Naples , Italy
| | - Robin J Tyacke
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
| | - Antonio Martin-Bastida
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
- Department of Neurology and Neurosciences, Clinica Universidad de Navarra , Pamplona-Madrid , Spain
| | - Roger N Gunn
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
| | - David J Nutt
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
| | - Paul Edison
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
| | - Paola Piccini
- Department of Brain Sciences, Imperial College London, Hammersmith Hospital , London , UK
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8
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Kumar A, Shandal V, Juhász C, Chugani HT. PET imaging in epilepsy. Nucl Med Mol Imaging 2022. [DOI: 10.1016/b978-0-12-822960-6.00049-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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9
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Chen Z, Haider A, Chen J, Xiao Z, Gobbi L, Honer M, Grether U, Arnold SE, Josephson L, Liang SH. The Repertoire of Small-Molecule PET Probes for Neuroinflammation Imaging: Challenges and Opportunities beyond TSPO. J Med Chem 2021; 64:17656-17689. [PMID: 34905377 PMCID: PMC9094091 DOI: 10.1021/acs.jmedchem.1c01571] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Neuroinflammation is an adaptive response of the central nervous system to diverse potentially injurious stimuli, which is closely associated with neurodegeneration and typically characterized by activation of microglia and astrocytes. As a noninvasive and translational molecular imaging tool, positron emission tomography (PET) could provide a better understanding of neuroinflammation and its role in neurodegenerative diseases. Ligands to translator protein (TSPO), a putative marker of neuroinflammation, have been the most commonly studied in this context, but they suffer from serious limitations. Herein we present a repertoire of different structural chemotypes and novel PET ligand design for classical and emerging neuroinflammatory targets beyond TSPO. We believe that this Perspective will support multidisciplinary collaborations in academic and industrial institutions working on neuroinflammation and facilitate the progress of neuroinflammation PET probe development for clinical use.
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Affiliation(s)
- Zhen Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Ahmed Haider
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Jiahui Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Zhiwei Xiao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Luca Gobbi
- Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Michael Honer
- Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Uwe Grether
- Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Steven E. Arnold
- Department of Neurology and the Massachusetts Alzheimer’s Disease Research Center, Massachusetts General Hospital, Harvard Medical School, 114 16th Street, Charlestown, Massachusetts 02129, USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
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10
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Klenner MA, Pascali G, Fraser BH, Darwish TA. Kinetic isotope effects and synthetic strategies for deuterated carbon-11 and fluorine-18 labelled PET radiopharmaceuticals. Nucl Med Biol 2021; 96-97:112-147. [PMID: 33892374 DOI: 10.1016/j.nucmedbio.2021.03.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 03/19/2021] [Accepted: 03/30/2021] [Indexed: 11/22/2022]
Abstract
The deuterium labelling of pharmaceuticals is a useful strategy for altering pharmacokinetic properties, particularly for improving metabolic resistance. The pharmacological effects of such metabolites are often assumed to be negligible during standard drug discovery and are factored in later at the clinical phases of development, where the risks and benefits of the treatment and side-effects can be wholly assessed. This paradigm does not translate to the discovery of radiopharmaceuticals, however, as the confounding effects of radiometabolites can inevitably show in preliminary positron emission tomography (PET) scans and thus complicate interpretation. Consequently, the formation of radiometabolites is crucial to take into consideration, compared to non-radioactive metabolites, and the application of deuterium labelling is a particularly attractive approach to minimise radiometabolite formation. Herein, we provide a comprehensive overview of the deuterated carbon-11 and fluorine-18 radiopharmaceuticals employed in PET imaging experiments. Specifically, we explore six categories of deuterated radiopharmaceuticals used to investigate the activities of monoamine oxygenase (MAO), choline, translocator protein (TSPO), vesicular monoamine transporter 2 (VMAT2), neurotransmission and the diagnosis of Alzheimer's disease; from which we derive four prominent deuteration strategies giving rise to a kinetic isotope effect (KIE) for reducing the rate of metabolism. Synthetic approaches for over thirty of these deuterated radiopharmaceuticals are discussed from the perspective of deuterium and radioisotope incorporation, alongside an evaluation of the deuterium labelling and radiolabelling efficacies across these independent studies. Clinical and manufacturing implications are also discussed to provide a more comprehensive overview of how deuterated radiopharmaceuticals may be introduced to routine practice.
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Affiliation(s)
- Mitchell A Klenner
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia; Department of Nuclear Medicine and PET, Liverpool Hospital, Liverpool, NSW 2170, Australia.
| | - Giancarlo Pascali
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia; Department of Nuclear Medicine and PET, Prince of Wales Hospital, Randwick, NSW 2031, Australia; School of Chemistry, University of New South Wales (UNSW), Kensington, NSW 2052, Australia
| | - Benjamin H Fraser
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Tamim A Darwish
- National Deuteration Facility (NDF) & Human Health, Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
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11
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Narayanaswami V, Tong J, Schifani C, Bloomfield PM, Dahl K, Vasdev N. Preclinical Evaluation of TSPO and MAO-B PET Radiotracers in an LPS Model of Neuroinflammation. PET Clin 2021; 16:233-247. [PMID: 33648665 DOI: 10.1016/j.cpet.2020.12.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Discovery of novel PET radiotracers targeting neuroinflammation (microglia and astrocytes) is actively pursued. Employing a lipopolysaccharide (LPS) rat model, this longitudinal study evaluated the translocator protein 18-kDa radiotracer [18F]FEPPA (primarily microglia) and monoamine oxidase B radiotracers [11C]L-deprenyl and [11C]SL25.1188 (astrocytes preferred). Increased [18F]FEPPA binding peaked at 1 week in LPS-injected striatum whereas increased lazabemide-sensitive [11C]L-deprenyl binding developed later. No increase in radiotracer uptake was observed for [11C]SL25.1188. The unilateral intrastriatal LPS rat model may serve as a useful tool for benchmarking PET tracers targeted toward distinct phases of neuroinflammatory reactions involving both microglia and astrocytes.
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Affiliation(s)
- Vidya Narayanaswami
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room 270, Toronto, Ontario M5T 1R8, Canada
| | - Junchao Tong
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room 339, Toronto, Ontario M5T 1R8, Canada
| | - Christin Schifani
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room 270, Toronto, Ontario M5T 1R8, Canada
| | - Peter M Bloomfield
- Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room B26A, Toronto, Ontario M5T 1R8, Canada
| | - Kenneth Dahl
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College Street, Room B02, Toronto, Ontario M5T 1R8, Canada
| | - Neil Vasdev
- Department of Psychiatry, Brain Health Imaging Centre, Azrieli Centre for Neuro-Radiochemistry, Centre for Addiction and Mental Health, University of Toronto, 250 College Street, Room PET G2, Toronto, Ontario M5T 1R8, Canada.
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12
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Sarkar S, Biswas SC. Astrocyte subtype-specific approach to Alzheimer's disease treatment. Neurochem Int 2021; 145:104956. [PMID: 33503465 DOI: 10.1016/j.neuint.2021.104956] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 01/01/2021] [Accepted: 01/05/2021] [Indexed: 01/08/2023]
Abstract
Astrocytes respond to any pathological condition in the central nervous system (CNS) including Alzheimer's disease (AD), and this response is called astrocyte reactivity. Astrocyte reaction to a CNS insult is a highly heterogeneous phenomenon in which the astrocytes undergo a set of morphological, molecular and functional changes with a characteristic secretome profile. Such astrocytes are termed as 'reactive astrocytes'. Controversies regarding the reactive astrocytes abound. Recently, a continuum of reactive astrocyte profiles with distinct transcriptional states has been identified. Among them, disease-associated astrocytes (DAA) were uniquely present in AD mice and expressed a signature set of genes implicated in complement cascade, endocytosis and aging. Earlier, two stimulus-specific reactive astrocyte subtypes with their unique transcriptomic signatures were identified using mouse models of neuroinflammation and ischemia and termed as A1 astrocytes (detrimental) and A2 astrocytes (beneficial) respectively. Interestingly, although most of the A1 signature genes were also detected in DAA, as opposed to A2 astrocyte signatures, some of the A1 specific genes were expressed in other astrocyte subtypes, indicating that these nomenclature-based signatures are not very specific. In this review, we elaborate the disparate functions and cytokine profiles of reactive astrocyte subtypes in AD and tried to distinguish them by designating neurotoxic astrocytes as A1-like and neuroprotective ones as A2-like without directly referring to the A1/A2 original nomenclature. We have also focused on the dual nature from a functional perspective of some cytokines depending on AD-stage, highlighting a number of them as major candidates in AD therapy. Therefore, we suggest that promoting subtype-specific beneficial roles, inhibiting subtype-specific detrimental roles or targeting subtype-specific cytokines constitute a novel therapeutic approach to AD treatment.
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Affiliation(s)
- Sukanya Sarkar
- Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata, 700 032, India
| | - Subhas C Biswas
- Cell Biology and Physiology Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata, 700 032, India.
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13
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Villemagne VL, Barkhof F, Garibotto V, Landau SM, Nordberg A, van Berckel BNM. Molecular Imaging Approaches in Dementia. Radiology 2021; 298:517-530. [PMID: 33464184 DOI: 10.1148/radiol.2020200028] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The increasing prevalence of dementia worldwide places a high demand on healthcare providers to perform a diagnostic work-up in relatively early stages of the disease, given that the pathologic process usually begins decades before symptoms are evident. Structural imaging is recommended to rule out other disorders and can only provide diagnosis in a late stage with limited specificity. Where PET imaging previously focused on the spatial pattern of hypometabolism, the past decade has seen the development of novel tracers to demonstrate characteristic protein abnormalities. Molecular imaging using PET/SPECT is able to show amyloid and tau deposition in Alzheimer disease and dopamine depletion in parkinsonian disorders starting decades before symptom onset. Novel tracers for neuroinflammation and synaptic density are being developed to further unravel the molecular pathologic characteristics of dementia disorders. In this article, the authors review the current status of established and emerging PET tracers in a diagnostic setting and also their value as prognostic markers in research studies and outcome measures for clinical trials in Alzheimer disease.
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Affiliation(s)
- Victor L Villemagne
- From the Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pa (V.L.V.); Department of Medicine, the University of Melbourne, Melbourne, Australia (V.L.V.); Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, VU University Medical Center, Amsterdam, the Netherlands (F.B., B.N.M.v.B.); UCL institutes of Neurology and Healthcare Engineering, London, England (F.B.); Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospitals and Laboratory of Neuroimaging and Innovative Molecular Tracers, Geneva University, Geneva, Switzerland (V.G.); Helen Wills Neuroscience Institute, University of California, Berkeley, Calif (S.M.L.); Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, Calif (S.M.L.); Department of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden (A.N.); and Theme Aging, Karolinska University Hospital, Stockholm, Sweden (A.N.)
| | - Frederik Barkhof
- From the Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pa (V.L.V.); Department of Medicine, the University of Melbourne, Melbourne, Australia (V.L.V.); Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, VU University Medical Center, Amsterdam, the Netherlands (F.B., B.N.M.v.B.); UCL institutes of Neurology and Healthcare Engineering, London, England (F.B.); Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospitals and Laboratory of Neuroimaging and Innovative Molecular Tracers, Geneva University, Geneva, Switzerland (V.G.); Helen Wills Neuroscience Institute, University of California, Berkeley, Calif (S.M.L.); Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, Calif (S.M.L.); Department of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden (A.N.); and Theme Aging, Karolinska University Hospital, Stockholm, Sweden (A.N.)
| | - Valentina Garibotto
- From the Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pa (V.L.V.); Department of Medicine, the University of Melbourne, Melbourne, Australia (V.L.V.); Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, VU University Medical Center, Amsterdam, the Netherlands (F.B., B.N.M.v.B.); UCL institutes of Neurology and Healthcare Engineering, London, England (F.B.); Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospitals and Laboratory of Neuroimaging and Innovative Molecular Tracers, Geneva University, Geneva, Switzerland (V.G.); Helen Wills Neuroscience Institute, University of California, Berkeley, Calif (S.M.L.); Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, Calif (S.M.L.); Department of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden (A.N.); and Theme Aging, Karolinska University Hospital, Stockholm, Sweden (A.N.)
| | - Susan M Landau
- From the Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pa (V.L.V.); Department of Medicine, the University of Melbourne, Melbourne, Australia (V.L.V.); Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, VU University Medical Center, Amsterdam, the Netherlands (F.B., B.N.M.v.B.); UCL institutes of Neurology and Healthcare Engineering, London, England (F.B.); Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospitals and Laboratory of Neuroimaging and Innovative Molecular Tracers, Geneva University, Geneva, Switzerland (V.G.); Helen Wills Neuroscience Institute, University of California, Berkeley, Calif (S.M.L.); Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, Calif (S.M.L.); Department of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden (A.N.); and Theme Aging, Karolinska University Hospital, Stockholm, Sweden (A.N.)
| | - Agneta Nordberg
- From the Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pa (V.L.V.); Department of Medicine, the University of Melbourne, Melbourne, Australia (V.L.V.); Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, VU University Medical Center, Amsterdam, the Netherlands (F.B., B.N.M.v.B.); UCL institutes of Neurology and Healthcare Engineering, London, England (F.B.); Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospitals and Laboratory of Neuroimaging and Innovative Molecular Tracers, Geneva University, Geneva, Switzerland (V.G.); Helen Wills Neuroscience Institute, University of California, Berkeley, Calif (S.M.L.); Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, Calif (S.M.L.); Department of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden (A.N.); and Theme Aging, Karolinska University Hospital, Stockholm, Sweden (A.N.)
| | - Bart N M van Berckel
- From the Department of Psychiatry, University of Pittsburgh, Pittsburgh, Pa (V.L.V.); Department of Medicine, the University of Melbourne, Melbourne, Australia (V.L.V.); Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, VU University Medical Center, Amsterdam, the Netherlands (F.B., B.N.M.v.B.); UCL institutes of Neurology and Healthcare Engineering, London, England (F.B.); Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospitals and Laboratory of Neuroimaging and Innovative Molecular Tracers, Geneva University, Geneva, Switzerland (V.G.); Helen Wills Neuroscience Institute, University of California, Berkeley, Calif (S.M.L.); Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, Calif (S.M.L.); Department of Neurobiology, Care Sciences and Society, Center for Alzheimer Research, Karolinska Institutet, Stockholm, Sweden (A.N.); and Theme Aging, Karolinska University Hospital, Stockholm, Sweden (A.N.)
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14
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Astroglial tracer BU99008 detects multiple binding sites in Alzheimer's disease brain. Mol Psychiatry 2021; 26:5833-5847. [PMID: 33888872 PMCID: PMC8758481 DOI: 10.1038/s41380-021-01101-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/17/2021] [Accepted: 04/01/2021] [Indexed: 12/15/2022]
Abstract
With reactive astrogliosis being established as one of the hallmarks of Alzheimer's disease (AD), there is high interest in developing novel positron emission tomography (PET) tracers to detect early astrocyte reactivity. BU99008, a novel astrocytic PET ligand targeting imidazoline-2 binding sites (I2BS) on astrocytes, might be a suitable candidate. Here we demonstrate for the first time that BU99008 could visualise reactive astrogliosis in postmortem AD brains and propose a multiple binding site [Super-high-affinity (SH), High-affinity (HA) and Low-affinity (LA)] model for BU99008, I2BS specific ligands (2-BFI and BU224) and deprenyl in AD and control (CN) brains. The proportion (%) and affinities of these sites varied significantly between the BU99008, 2-BFI, BU224 and deprenyl in AD and CN brains. Regional binding studies demonstrated significantly higher 3H-BU99008 binding in AD brain regions compared to CN. Comparative autoradiography studies reinforced these findings, showing higher specific binding for 3H-BU99008 than 3H-Deprenyl in sporadic AD brain compared to CN, implying that they might have different targets. The data clearly shows that BU99008 could detect I2BS expressing reactive astrocytes with good selectivity and specificity and hence be a potential attractive clinical astrocytic PET tracer for gaining further insight into the role of reactive astrogliosis in AD.
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15
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Hoffman CE, Parker WE, Rapoport BI, Zhao M, Ma H, Schwartz TH. Innovations in the Neurosurgical Management of Epilepsy. World Neurosurg 2020; 139:775-788. [PMID: 32689698 DOI: 10.1016/j.wneu.2020.03.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 03/02/2020] [Indexed: 10/23/2022]
Abstract
Technical limitations and clinical challenges have historically limited the diagnostic tools and treatment methods available for surgical approaches to the management of epilepsy. By contrast, recent technological innovations in several areas hold significant promise in improving outcomes and decreasing morbidity. We review innovations in the neurosurgical management of epilepsy in several areas, including wireless recording and stimulation systems (particularly responsive neurostimulation [NeuroPace]), conformal electrodes for high-resolution electrocorticography, robot-assisted stereotactic surgery, optogenetics and optical imaging methods, novel positron emission tomography ligands, and new applications of focused ultrasonography. Investigation into genetic causes of and susceptibilities to epilepsy has introduced a new era of precision medicine, enabling the understanding of cell signaling mechanisms underlying epileptic activity as well as patient-specific molecularly targeted treatment options. We discuss the emerging path to individualized treatment plans, predicted outcomes, and improved selection of effective interventions, on the basis of these developments.
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Affiliation(s)
- Caitlin E Hoffman
- Department of Neurological Surgery, Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York, USA.
| | - Whitney E Parker
- Department of Neurological Surgery, Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York, USA
| | - Benjamin I Rapoport
- Department of Neurological Surgery, Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York, USA
| | - Mingrui Zhao
- Department of Neurological Surgery, Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York, USA
| | - Hongtao Ma
- Department of Neurological Surgery, Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York, USA
| | - Theodore H Schwartz
- Department of Neurological Surgery, Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York, USA
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16
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Bascuñana P, Gendron T, Sander K, Jahreis I, Polyak A, Ross TL, Bankstahl M, Arstad E, Bankstahl JP. Ex vivo characterization of neuroinflammatory and neuroreceptor changes during epileptogenesis using candidate positron emission tomography biomarkers. Epilepsia 2019; 60:2325-2333. [PMID: 31571210 DOI: 10.1111/epi.16353] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 09/04/2019] [Accepted: 09/04/2019] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Identification of patients at risk of developing epilepsy before the first spontaneous seizure may promote the development of preventive treatment providing opportunity to stop or slow down the disease. METHODS As development of novel radiotracers and on-site setup of existing radiotracers is highly time-consuming and expensive, we used dual-centre in vitro autoradiography as an approach to characterize the potential of innovative radiotracers in the context of epilepsy development. Using brain slices from the same group of rats, we aimed to characterise the evolution of neuroinflammation and expression of inhibitory and excitatory neuroreceptors during epileptogenesis using translational positron emission tomography (PET) tracers; 18 F-flumazenil (18 F-FMZ; GABAA receptor), 18 F-FPEB (metabotropic glutamate receptor 5; mGluR5), 18 F-flutriciclamide (translocator protein; TSPO, microglia activation) and 18 F-deprenyl (monoamine oxidase B, astroglia activation). Autoradiography images from selected time points after pilocarpine-induced status epilepticus (SE; baseline, 24 and 48 hours, 5, 10 and 15 days and 6 and 12-14 weeks after SE) were normalized to a calibration curve, co-registered to an MRI-based 2D region-of-interest atlas, and activity concentration (Bq/mm2 ) was calculated. RESULTS In epileptogenesis-associated brain regions, 18 F-FMZ and 18 F-FPEB showed an early decrease after SE. 18 F-FMZ decrease was maintained in the latent phase and further reduced in the chronic epileptic animals, while 18 F-FPEB signal recovered from day 10, reaching baseline levels in chronic epilepsy. 18 F-flutriciclamide showed an increase of activated microglia at 24 hours after SE, peaking at 5-15 days and decreasing during the chronic phase. On the other hand, 18 F-deprenyl autoradiography showed late astrogliosis, peaking in the chronic phase. SIGNIFICANCE Autoradiography revealed different evolution of the selected targets during epileptogenesis. Our results suggest an advantage of combined imaging of inter-related targets like glutamate and GABAA receptors, or microglia and astrocyte activation, in order to identify important interactions, especially when using PET imaging for the evaluation of novel treatments.
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Affiliation(s)
- Pablo Bascuñana
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Thibault Gendron
- Institute of Nuclear Medicine, University College London, London, UK.,Department of Chemistry, University College London, London, UK
| | - Kerstin Sander
- Institute of Nuclear Medicine, University College London, London, UK.,Department of Chemistry, University College London, London, UK
| | - Ina Jahreis
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany.,Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine, Hannover, Germany
| | - Andras Polyak
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Tobias L Ross
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | - Marion Bankstahl
- Department of Pharmacology, Toxicology and Pharmacy, University of Veterinary Medicine, Hannover, Germany.,Institute for Laboratory Animal Science, Hannover Medical School, Hannover, Germany
| | - Erik Arstad
- Institute of Nuclear Medicine, University College London, London, UK.,Department of Chemistry, University College London, London, UK
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
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17
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Carter SF, Herholz K, Rosa-Neto P, Pellerin L, Nordberg A, Zimmer ER. Astrocyte Biomarkers in Alzheimer's Disease. Trends Mol Med 2019; 25:77-95. [PMID: 30611668 DOI: 10.1016/j.molmed.2018.11.006] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 11/30/2018] [Accepted: 11/30/2018] [Indexed: 01/01/2023]
Abstract
Astrocytic contributions to Alzheimer's disease (AD) progression were, until recently, largely overlooked. Astrocytes are integral to normal brain function and astrocyte reactivity is an early feature of AD, potentially providing a promising target for preclinical diagnosis and treatment. Several in vivo AD biomarkers already exist, but presently there is a paucity of specific and sensitive in vivo astrocyte biomarkers that can accurately measure preclinical AD. Measuring monoamine oxidase-B with neuroimaging and glial fibrillary acidic protein from bodily fluids are biomarkers that are currently available. Developing novel, more specific, and sensitive astrocyte biomarkers will make it possible to pharmaceutically target chemical pathways that preserve beneficial astrocytic functions in response to AD pathology. This review discusses astrocyte biomarkers in the context of AD.
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Affiliation(s)
- Stephen F Carter
- Wolfson Molecular Imaging Centre, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
| | - Karl Herholz
- Wolfson Molecular Imaging Centre, Division of Neuroscience and Experimental Psychology, University of Manchester, Manchester, United Kingdom
| | - Pedro Rosa-Neto
- Translational Neuroimaging Laboratory, McGill Centre for Studies in Aging, McGill University, Montreal, Canada; Douglas Hospital Research Centre, Montreal, Canada; Montreal Neurological Institute, Montreal, Canada
| | - Luc Pellerin
- Département de Physiologie, Université de Lausanne, Lausanne, Switzerland; Centre de Résonance Magnétique des Systèmes Biologiques, UMR5536 CNRS, LabEx TRAIL-IBIO, Université de Bordeaux, Bordeaux Cedex 33760, France
| | - Agneta Nordberg
- Division of Clinical Geriatrics, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet, Stockholm, Sweden; Theme Aging, Karolinska University Hospital, Huddinge, Sweden
| | - Eduardo R Zimmer
- Department of Pharmacology, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Graduate Program in Biological Sciences: Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Graduate Program in Biological Sciences: Pharmacology and Therapeutics, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Brain Institute (BraIns) of Rio Grande do Sul, Porto Alegre, Brazil; Website: www.zimmer-lab.org.
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18
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Ravizza T, Vezzani A. Pharmacological targeting of brain inflammation in epilepsy: Therapeutic perspectives from experimental and clinical studies. Epilepsia Open 2018; 3:133-142. [PMID: 30564772 PMCID: PMC6293065 DOI: 10.1002/epi4.12242] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2018] [Indexed: 12/16/2022] Open
Abstract
Increasing evidence supports a pathogenic role of unabated neuroinflammation in various central nervous system (CNS) diseases, including epilepsy. Neuroinflammation is not a bystander phenomenon of the diseased brain tissue, but it may contribute to neuronal hyperexcitability underlying seizure generation, cell loss, and neurologic comorbidities. Several molecules, which constitute the inflammatory milieu in the epileptogenic area, activate signaling pathways in neurons and glia resulting in pathologic modifications of cell function, which ultimately lead to alterations in synaptic transmission and plasticity. Herein we report the up-to-date experimental and clinical evidence that supports the neuromodulatory role of inflammatory mediators, their related signaling pathways, and involvement in epilepsy. We discuss how these mechanisms can be harnessed to discover and validate targets for novel therapeutics, which may prevent or control pharmacoresistant epilepsies.
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Affiliation(s)
- Teresa Ravizza
- Department of NeuroscienceIRCCS – Mario Negri Institute for Pharmacological ResearchMilanoItaly
| | - Annamaria Vezzani
- Department of NeuroscienceIRCCS – Mario Negri Institute for Pharmacological ResearchMilanoItaly
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19
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Tong J, Rathitharan G, Meyer JH, Furukawa Y, Ang LC, Boileau I, Guttman M, Hornykiewicz O, Kish SJ. Brain monoamine oxidase B and A in human parkinsonian dopamine deficiency disorders. Brain 2017; 140:2460-2474. [PMID: 29050386 DOI: 10.1093/brain/awx172] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 05/30/2017] [Indexed: 11/13/2022] Open
Abstract
See Jellinger (doi:10.1093/awx190) for a scientific commentary on this article. The enzyme monoamine oxidases (B and A subtypes, encoded by MAOB and MAOA, respectively) are drug targets in the treatment of Parkinson's disease. Inhibitors of MAOB are used clinically in Parkinson's disease for symptomatic purposes whereas the potential disease-modifying effect of monoamine oxidase inhibitors is debated. As astroglial cells express high levels of MAOB, the enzyme has been proposed as a brain imaging marker of astrogliosis, a cellular process possibly involved in Parkinson's disease pathogenesis as elevation of MAOB in astrocytes might be harmful. Since brain monoamine oxidase status in Parkinson's disease is uncertain, our objective was to measure, by quantitative immunoblotting in autopsied brain homogenates, protein levels of both monoamine oxidases in three different degenerative parkinsonian disorders: Parkinson's disease (n = 11), multiple system atrophy (n = 11), and progressive supranuclear palsy (n = 16) and in matched controls (n = 16). We hypothesized that if MAOB is 'substantially' localized to astroglial cells, MAOB levels should be generally associated with standard astroglial protein measures (e.g. glial fibrillary acidic protein). MAOB levels were increased in degenerating putamen (+83%) and substantia nigra (+10%, non-significant) in multiple system atrophy; in caudate (+26%), putamen (+27%), frontal cortex (+31%) and substantia nigra (+23%) of progressive supranuclear palsy; and in frontal cortex (+33%), but not in substantia nigra of Parkinson's disease, a region we previously reported no increase in astrocyte protein markers. Although the magnitude of MAOB increase was less than those of standard astrocytic markers, significant positive correlations were observed amongst the astrocyte proteins and MAOB. Despite suggestions that MAOA (versus MAOB) is primarily responsible for metabolism of dopamine in dopamine neurons, there was no loss of the enzyme in the parkinsonian substantia nigra; instead, increased nigral levels of a MAOA fragment and 'turnover' of the enzyme were observed in the conditions. Our findings provide support that MAOB might serve as a biochemical imaging marker, albeit not entirely specific, for astrocyte activation in human brain. The observation that MAOB protein concentration is generally increased in degenerating brain areas in multiple system atrophy (especially putamen) and in progressive supranuclear palsy, but not in the nigra in Parkinson's disease, also distinguishes astrocyte behaviour in Parkinson's disease from that in the two 'Parkinson-plus' conditions. The question remains whether suppression of either MAOB in astrocytes or MAOA in dopamine neurons might influence progression of the parkinsonian disorders.
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Affiliation(s)
- Junchao Tong
- Preclinical Imaging Unit, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.,Human Brain Laboratory, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Gausiha Rathitharan
- Human Brain Laboratory, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Jeffrey H Meyer
- Research Imaging Centre and Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Yoshiaki Furukawa
- Department of Neurology, Juntendo Tokyo Koto Geriatric Medical Center, and Faculty of Medicine, University and Post Graduate University of Juntendo, Tokyo, Japan
| | - Lee-Cyn Ang
- Division of Neuropathology, London Health Science Centre, University of Western Ontario, London, Ontario, Canada
| | - Isabelle Boileau
- Addiction Imaging Research Group, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Mark Guttman
- Centre for Movement Disorders, Markham, Ontario, Canada
| | - Oleh Hornykiewicz
- Centre for Brain Research, Medical University of Vienna, Spitalgasse 4, A-1090 Vienna, Austria
| | - Stephen J Kish
- Human Brain Laboratory, Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
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20
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Koepp MJ, Årstad E, Bankstahl JP, Dedeurwaerdere S, Friedman A, Potschka H, Ravizza T, Theodore WH, Baram TZ. Neuroinflammation imaging markers for epileptogenesis. Epilepsia 2017; 58 Suppl 3:11-19. [PMID: 28675560 DOI: 10.1111/epi.13778] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2017] [Indexed: 12/23/2022]
Abstract
Epilepsy can be a devastating disorder. In addition to debilitating seizures, epilepsy can cause cognitive and emotional problems with reduced quality of life. Therefore, the major aim is to prevent the disorder in the first place: identify, detect, and reverse the processes responsible for its onset, and monitor and treat its progression. Epilepsy often occurs following a latent period of months to years (epileptogenesis) as a consequence of a brain insult, such as head trauma, stroke, or status epilepticus. Although this latent period clearly represents a therapeutic window, we are not able to stratify patients at risk for long-term epilepsy, which is prerequisite for preventative clinical trials. Moreover, because of the length of the latent period, an early biomarker for treatment response would be of high value. Finally, mechanistic biomarkers of epileptogenesis may provide more profound insight in the process of disease development.
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Affiliation(s)
- Matthias J Koepp
- Institute of Neurology, University College London, London, United Kingdom
| | - Eric Årstad
- Department of Chemistry and Institute of Nuclear Medicine, University College London, London, United Kingdom
| | - Jens P Bankstahl
- Department of Nuclear Medicine, Hannover Medical School, Hannover, Germany
| | | | - Alon Friedman
- Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Dalhousie University, Halifax, Nova Scotia, Canada
| | - Heidrun Potschka
- Institute of Pharmacology, Toxicology, and Pharmacy, Ludwig-Maximilians-University, Munich, Germany
| | - Teresa Ravizza
- Department of Neuroscience, IRCCS-Institute for Pharmacological Research Mario Negri, Milan, Italy
| | | | - Tallie Z Baram
- Departments of Pediatrics, Anatomy/Neurobiology, Neurology, University of California-Irvine, Irvine, California, U.S.A
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21
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Arakawa R, Stenkrona P, Takano A, Nag S, Maior RS, Halldin C. Test-retest reproducibility of [ 11C]-L-deprenyl-D 2 binding to MAO-B in the human brain. EJNMMI Res 2017. [PMID: 28634836 PMCID: PMC5478550 DOI: 10.1186/s13550-017-0301-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Background [11C]-l-deprenyl-D2 is a positron emission tomography (PET) radioligand for measurement of the monoamine oxidase B (MAO-B) activity in vivo brain. The estimation of the test-retest reproducibility is important for accurate interpretation of PET studies. Results We performed two [11C]-l-deprenyl-D2 scans for six healthy subjects and evaluated the test-retest variability of this radioligand. MAO-B binding was quantified by two tissue compartment model (2TCM) with three rate constants (K1, k2, k3) using metabolite-corrected plasma radioactivity. The λk3 defined as (K1/k2) × k3 was also calculated. The correlation between MAO-B binding and age, and the effect of partial volume effect correction (PVEc) for the reproducibility were also estimated. %difference of k3 was 2.6% (medial frontal cortex) to 10.3% (hippocampus), and that of λk3 was 5.0% (thalamus) to 9.2% (cerebellum). Mean %difference of all regions were 5.3 and 7.0% in k3 and λk3, respectively. All regions showed below 10% variabilities except the hippocampus in k3 (10.3%). Intraclass correlation coefficient (ICC) of k3 was 0.78 (hippocampus) to 0.98 (medial frontal cortex), and that of λk3 was 0.78 (hippocampus) to 0.95 (thalamus). Mean ICC were 0.94 and 0.89 in k3 and λk3, respectively. The highest positive correlation with age was observed in the hippocampus, as r = 0.75 in k3 and 0.76 in λk3. After PVEc, mean %difference were 5.6 and 7.2% in k3 and λk3, respectively. Mean ICC were 0.92 and 0.90 for k3 and λk3, respectively. These values were almost the same as those before PVEc. Conclusions The present results indicate that k3 and λk3 of [11C]-l-deprenyl-D2 are reliable parameters for test-retest reproducibility with healthy subjects both before and after PVEc. The studies with patients of larger sample size are required for further clinical applications.
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Affiliation(s)
- Ryosuke Arakawa
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.
| | - Per Stenkrona
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Akihiro Takano
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Sangram Nag
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
| | - Rafael S Maior
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden.,Primate Center and Laboratory of Neurosciences and Behavior, Department of Physiological Sciences, Institute of Biology, University of Brasilia, Brasilia, Brazil
| | - Christer Halldin
- Department of Clinical Neuroscience, Center for Psychiatry Research, Karolinska Institutet and Stockholm County Council, Stockholm, Sweden
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Cerami C, Iaccarino L, Perani D. Molecular Imaging of Neuroinflammation in Neurodegenerative Dementias: The Role of In Vivo PET Imaging. Int J Mol Sci 2017; 18:ijms18050993. [PMID: 28475165 PMCID: PMC5454906 DOI: 10.3390/ijms18050993] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 04/14/2017] [Accepted: 04/18/2017] [Indexed: 11/16/2022] Open
Abstract
Neurodegeneration elicits neuroinflammatory responses to kill pathogens, clear debris and support tissue repair. Neuroinflammation is a dynamic biological response characterized by the recruitment of innate and adaptive immune system cells in the site of tissue damage. Resident microglia and infiltrating immune cells partake in the restoration of central nervous system homeostasis. Nevertheless, their activation may shift to chronic and aggressive responses, which jeopardize neuron survival and may contribute to the disease process itself. Positron Emission Tomography (PET) molecular imaging represents a unique tool contributing to in vivo investigating of neuroinflammatory processes in patients. In the present review, we first provide an overview on the molecular basis of neuroinflammation in neurodegenerative diseases with emphasis on microglia activation, astrocytosis and the molecular targets for PET imaging. Then, we review the state-of-the-art of in vivo PET imaging for neuroinflammation in dementia conditions associated with different proteinopathies, such as Alzheimer’s disease, frontotemporal lobar degeneration and Parkinsonian spectrum.
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Affiliation(s)
- Chiara Cerami
- Clinical Neuroscience Department, San Raffaele Turro Hospital, Milan 20121-20162, Italy.
- Division of Neuroscience, San Raffaele Scientific Institute, Milan 20121-20162, Italy.
| | - Leonardo Iaccarino
- Division of Neuroscience, San Raffaele Scientific Institute, Milan 20121-20162, Italy.
- Faculty of Psychology and Molecular Medicine Doctoral Course, Vita-Salute San Raffaele University, Milan 20121-20162, Italy.
| | - Daniela Perani
- Division of Neuroscience, San Raffaele Scientific Institute, Milan 20121-20162, Italy.
- Faculty of Psychology and Molecular Medicine Doctoral Course, Vita-Salute San Raffaele University, Milan 20121-20162, Italy.
- Nuclear Medicine Unit, San Raffaele Hospital, Milan 20121-20162, Italy.
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Vezzani A, Pascente R, Ravizza T. Biomarkers of Epileptogenesis: The Focus on Glia and Cognitive Dysfunctions. Neurochem Res 2017; 42:2089-2098. [PMID: 28434163 DOI: 10.1007/s11064-017-2271-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 04/12/2017] [Accepted: 04/17/2017] [Indexed: 12/31/2022]
Abstract
The need to find measures that reliably predict the onset of epilepsy after injurious events or how the patient will respond to anti-seizure drugs led to intensive pre-clinical and clinical research to discover non-invasive biomarkers that could increase the sensitivity of existing clinical indicators. The use of experimental models of epileptogenesis and of drug-resistance is instrumental to select the most promising approaches to explore such biomarkers in the pre-clinical setting for further clinical validation. The approaches most frequently used to find clinically useful biomarkers of epileptogenesis include molecular brain imaging, EEG signal analysis and the measure of soluble molecules in biofluids which may reflect brain intrinsic events involved in epilepsy development. Among those, we focused our attention on proton magnetic resonance imaging (1H-MRS)-based analysis of astrocytic activation, and related blood biomarkers, since this cell population appears to be pivotally involved in various epileptogenesis processes triggered by differing insults. Moreover, we also investigated behavioral biomarkers by focusing on cognitive dysfunctions since this deficit represents a typical co-morbidity in epilepsy which may manifest even before the onset of spontaneous seizures. In this review article, we will report our recently published evidence supporting the utility of measuring astrocyte activation, the soluble molecules they release, and the associated cognitive deficits during epileptogenesis for early stratification of animals developing epilepsy. We will discuss the potential clinical translation of our findings for enriching the patient population in preventive clinical trials designed to study anti-epileptogenic treatments.
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Affiliation(s)
- Annamaria Vezzani
- Department of Neuroscience, IRCCS-Istituto Di Ricerche Farmacologiche Mario Negri, Via G. La Masa, 19, 20156, Milan, Italy.
| | - Rosaria Pascente
- Department of Neuroscience, IRCCS-Istituto Di Ricerche Farmacologiche Mario Negri, Via G. La Masa, 19, 20156, Milan, Italy
| | - Teresa Ravizza
- Department of Neuroscience, IRCCS-Istituto Di Ricerche Farmacologiche Mario Negri, Via G. La Masa, 19, 20156, Milan, Italy
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Kumar A, Chugani HT. The Role of Radionuclide Imaging in Epilepsy, Part 1: Sporadic Temporal and Extratemporal Lobe Epilepsy. J Nucl Med Technol 2017; 45:14-21. [PMID: 28258205 DOI: 10.2967/jnumed.112.114397] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 08/06/2013] [Indexed: 11/16/2022] Open
Abstract
Epilepsy is one of the most common yet diverse neurologic disorders, affecting almost 1%-2% of the population. Presently, radionuclide imaging such as PET and SPECT is not used in the primary diagnosis or evaluation of recent-onset epilepsy. However, it can play a unique and important role in certain specific situations, such as in noninvasive presurgical localization of epileptogenic brain regions in intractable-seizure patients being considered for epilepsy surgery. Radionuclide imaging can be particularly useful if MR imaging is either negative for lesions or shows several lesions of which only 1 or 2 are suspected to be epileptogenic and if electroencephalogram changes are equivocal or discordant with the structural imaging. Similarly, PET and SPECT can also be useful for evaluating the functional integrity of the rest of the brain and may provide useful information on the possible pathogenesis of the neurocognitive and behavioral abnormalities frequently observed in these patients.
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Affiliation(s)
- Ajay Kumar
- PET Center, Department of Pediatrics, Neurology, and Radiology, Children's Hospital of Michigan, Detroit Medical Center, Wayne State University School of Medicine, Detroit, Michigan
| | - Harry T Chugani
- PET Center, Department of Pediatrics, Neurology, and Radiology, Children's Hospital of Michigan, Detroit Medical Center, Wayne State University School of Medicine, Detroit, Michigan
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Svob Strac D, Pivac N, Smolders IJ, Fogel WA, De Deurwaerdere P, Di Giovanni G. Monoaminergic Mechanisms in Epilepsy May Offer Innovative Therapeutic Opportunity for Monoaminergic Multi-Target Drugs. Front Neurosci 2016; 10:492. [PMID: 27891070 PMCID: PMC5102907 DOI: 10.3389/fnins.2016.00492] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 10/13/2016] [Indexed: 12/22/2022] Open
Abstract
A large body of experimental and clinical evidence has strongly suggested that monoamines play an important role in regulating epileptogenesis, seizure susceptibility, convulsions, and comorbid psychiatric disorders commonly seen in people with epilepsy (PWE). However, neither the relative significance of individual monoamines nor their interaction has yet been fully clarified due to the complexity of these neurotransmitter systems. In addition, epilepsy is diverse, with many different seizure types and epilepsy syndromes, and the role played by monoamines may vary from one condition to another. In this review, we will focus on the role of serotonin, dopamine, noradrenaline, histamine, and melatonin in epilepsy. Recent experimental, clinical, and genetic evidence will be reviewed in consideration of the mutual relationship of monoamines with the other putative neurotransmitters. The complexity of epileptic pathogenesis may explain why the currently available drugs, developed according to the classic drug discovery paradigm of "one-molecule-one-target," have turned out to be effective only in a percentage of PWE. Although, no antiepileptic drugs currently target specifically monoaminergic systems, multi-target directed ligands acting on different monoaminergic proteins, present on both neurons and glia cells, may represent a new approach in the management of seizures, and their generation as well as comorbid neuropsychiatric disorders.
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Affiliation(s)
| | - Nela Pivac
- Division of Molecular Medicine, Rudjer Boskovic InstituteZagreb, Croatia
| | - Ilse J. Smolders
- Department of Pharmaceutical Chemistry and Drug Analysis, Vrije Universiteit BrusselBrussels, Belgium
| | - Wieslawa A. Fogel
- Department of Hormone Biochemistry, Medical University of LodzLodz, Poland
| | | | - Giuseppe Di Giovanni
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, University of MaltaMsida, Malta
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Lesniak A, Aarnio M, Jonsson A, Norberg T, Nyberg F, Gordh T. High-throughput screening and radioligand binding studies reveal monoamine oxidase-B as the primary binding target for d-deprenyl. Life Sci 2016; 152:231-7. [PMID: 27058977 DOI: 10.1016/j.lfs.2016.03.058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 03/30/2016] [Accepted: 03/31/2016] [Indexed: 12/24/2022]
Abstract
AIMS d-deprenyl is a useful positron emission tomography tracer for visualization of inflammatory processes. Studies with [(11)C]-d-deprenyl showed robust uptake in peripheral painful sites of patients with rheumatoid arthritis or chronic whiplash injury. The mechanism of preferential d-deprenyl uptake is not yet known, but the existence of a specific binding site was proposed. Thus, in the present study, we sought to identify the binding site for d-deprenyl and verify the hypothesis about the possibility of monoamine oxidase enzymes as major targets for this molecule. MAIN METHODS A high-throughput analysis of d-deprenyl activity towards 165G-protein coupled receptors and 84 enzyme targets was performed. Additionally, binding studies were used to verify the competition of [(3)H]d-deprenyl with ligands specific for targets identified in the high-throughput screen. KEY FINDINGS Our high-throughput investigation identified monoamine oxidase-B, monoamine oxidase-A and angiotensin converting enzyme as potential targets for d-deprenyl. Further competitive [(3)H]d-deprenyl binding studies with specific inhibitors identified monoamine oxidase-B as the major binding site. No evident high-affinity hits were identified among G-protein coupled receptors. SIGNIFICANCE Our study was the first to utilize a high-throughput screening approach to identify putative d-deprenyl targets. It verified 249 candidate proteins and confirmed the role of monoamine oxidase - B in d-deprenyl binding. Our results add knowledge about the possible mechanism of d-deprenyl binding, which might aid in explaining the increased uptake of this compound in peripheral inflammation. Monoamine oxidase-B will be further investigated in future studies utilizing human inflamed synovium.
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Affiliation(s)
- Anna Lesniak
- Uppsala University, Department of Pharmaceutical Biosciences, SE 751 24 Uppsala, Sweden.
| | - Mikko Aarnio
- Uppsala University Hospital, Department of Surgical Sciences, Anaesthesiology and Intensive Care, SE 751 85 Uppsala, Sweden
| | - Anna Jonsson
- Uppsala University, Department of Pharmaceutical Biosciences, SE 751 24 Uppsala, Sweden
| | - Thomas Norberg
- Uppsala University, Department of Chemistry, SE 751 23 Uppsala, Sweden
| | - Fred Nyberg
- Uppsala University, Department of Pharmaceutical Biosciences, SE 751 24 Uppsala, Sweden
| | - Torsten Gordh
- Uppsala University Hospital, Department of Surgical Sciences, Anaesthesiology and Intensive Care, SE 751 85 Uppsala, Sweden
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Abstract
Imaging is pivotal in the evaluation and management of patients with seizure disorders. Elegant structural neuroimaging with magnetic resonance imaging (MRI) may assist in determining the etiology of focal epilepsy and demonstrating the anatomical changes associated with seizure activity. The high diagnostic yield of MRI to identify the common pathological findings in individuals with focal seizures including mesial temporal sclerosis, vascular anomalies, low-grade glial neoplasms and malformations of cortical development has been demonstrated. Positron emission tomography (PET) is the most commonly performed interictal functional neuroimaging technique that may reveal a focal hypometabolic region concordant with seizure onset. Single photon emission computed tomography (SPECT) studies may assist performance of ictal neuroimaging in patients with pharmacoresistant focal epilepsy being considered for neurosurgical treatment. This chapter highlights neuroimaging developments and innovations, and provides a comprehensive overview of the imaging strategies used to improve the care and management of people with epilepsy.
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Matthews PM, Datta G. Positron-emission tomography molecular imaging of glia and myelin in drug discovery for multiple sclerosis. Expert Opin Drug Discov 2015; 10:557-70. [PMID: 25843125 DOI: 10.1517/17460441.2015.1032240] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Therapies acting on glial cells are being explored for new drug development for multiple sclerosis. Molecular imaging using positron-emission tomography (PET) could address relevant questions in early phase clinical trials. AREAS COVERED In this article, the authors critically review human PET methods that can be applied in specialised centres for imaging activated microglia and astrocytes and myelin. EXPERT OPINION Strengths of PET lie in the molecular selectivity, sensitivity and potential for absolute quantitation. Even now, translocator protein PET radioligands could be used in exploratory studies for interventions targeting brain microglial activation. The clinical and neuropathological meaningfulness of signal from PET radioligands reporting on astrocyte activation through cellular expression of either monoamine oxidase B or the I2-imidazoline receptor or metabolism of [(11)C]acetate can now explored. [(11)C] N-methyl-4,4'-diaminostilbene, a PET marker for myelin, could soon enter first human trials. However, use of any of these PET glial markers demands a well-focused hypothesis and a commitment to validation in the context of use. Enhanced access to these radioligands, standardisation of analyses and lowering the costs of using them are needed if their full promise is to be realised.
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Affiliation(s)
- Paul M Matthews
- Imperial College London, Division of Brain Sciences, Department of Medicine , E515, Burlington Danes Building, Du Cane Road, W12 0NN London , UK +44 02075942612 ; +44 02075946548 ;
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Fowler JS, Logan J, Shumay E, Alia-Klein N, Wang GJ, Volkow ND. Monoamine oxidase: radiotracer chemistry and human studies. J Labelled Comp Radiopharm 2015; 58:51-64. [PMID: 25678277 DOI: 10.1002/jlcr.3247] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 10/31/2014] [Indexed: 11/09/2022]
Abstract
Monoamine oxidase (MAO) oxidizes amines from both endogenous and exogenous sources thereby regulating the concentration of neurotransmitter amines such as serotonin, norepinephrine, and dopamine as well as many xenobiotics. MAO inhibitor drugs are used in the treatment of Parkinson's disease and in depression stimulating the development of radiotracer tools to probe the role of MAO in normal human biology and in disease. Over the past 30 years since the first radiotracers were developed and the first positron emission tomography (PET) images of MAO in humans were carried out, PET studies of brain MAO in healthy volunteers and in patients have identified different variables that have contributed to different MAO levels in brain and in peripheral organs. MAO radiotracers and PET have also been used to study the current and developing MAO inhibitor drugs including the selection of doses for clinical trials. In this article, we describe the following: (1) the development of MAO radiotracers; (2) human studies including the relationship of brain MAO levels to genotype, personality, neurological, and psychiatric disorders; and (3) examples of the use of MAO radiotracers in drug research and development. We will conclude with outstanding needs to improve the radiotracers that are currently used and possible new applications.
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Affiliation(s)
- Joanna S Fowler
- Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY, USA
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Hicks JW, Sadovski O, Parkes J, Houle S, Hay BA, Carter RL, Wilson AA, Vasdev N. Radiosynthesis and ex vivo evaluation of [18F]-(S)-3-(6-(3-fluoropropoxy)benzo[d]isoxazol-3-yl)-5-(methoxymethyl)oxazolidin-2-one for imaging MAO-B with PET. Bioorg Med Chem Lett 2015; 25:288-91. [DOI: 10.1016/j.bmcl.2014.11.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 11/14/2014] [Accepted: 11/17/2014] [Indexed: 11/17/2022]
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Amhaoul H, Staelens S, Dedeurwaerdere S. Imaging brain inflammation in epilepsy. Neuroscience 2014; 279:238-52. [DOI: 10.1016/j.neuroscience.2014.08.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/27/2014] [Accepted: 08/27/2014] [Indexed: 01/15/2023]
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Verkhratsky A, Marutle A, Rodríguez-Arellano JJ, Nordberg A. Glial Asthenia and Functional Paralysis: A New Perspective on Neurodegeneration and Alzheimer's Disease. Neuroscientist 2014; 21:552-568. [PMID: 25125026 DOI: 10.1177/1073858414547132] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Neuroglia are represented by several population of cells heterogeneous in structure and function that provide for the homeostasis of the brain and the spinal cord. Neuroglial cells are also central for neuroprotection and defence of the central nervous system against exo- and endogenous insults. At the early stages of neurodegenerative diseases including Alzheimer's disease neuroglial cells become asthenic and lose some of their homeostatic, neuroprotective, and defensive capabilities. Astroglial reactivity, for example, correlates with preservation of cognitive function in patients with mild cognitive impairment and prodromal Alzheimer's disease. Here, we overview the experimental data indicating glial paralysis in neurodegeneration and argue that loss of glial function is fundamental for defining the progression of neurodegenerative diseases.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, UK Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain Department of Neurosciences, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain University of Nizhny Novgorod, Nizhny Novgorod, Russia
| | - Amelia Marutle
- Karolinska Institutet, Dept NVS, Center for Alzheimer Research, Translational Alzheimer Neurobiology, Novum, Huddinge, Sweden
| | - J J Rodríguez-Arellano
- Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain Department of Neurosciences, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain
| | - Agneta Nordberg
- Karolinska Institutet, Dept NVS, Center for Alzheimer Research, Translational Alzheimer Neurobiology, Novum, Huddinge, Sweden Department of Geriatric Medicine, Karolinska University Hospital Huddinge, Stockholm, Sweden
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Tegler G, Estrada S, Hall H, Wanhainen A, Björck M, Sörensen J, Antoni G. Autoradiography screening of potential positron emission tomography tracers for asymptomatic abdominal aortic aneurysms. Ups J Med Sci 2014; 119:229-35. [PMID: 24555564 PMCID: PMC4116762 DOI: 10.3109/03009734.2014.894157] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
OBJECTIVE The aetiology and early pathophysiological mechanisms of aortic aneurysm formation are still unknown and challenging to study in vivo. Positron emission tomography (PET) is a potentially valuable instrument for non-invasive in vivo pathophysiological studies. No specific tracer to identify the pathophysiological process of aneurysmal dilatation is yet available, however. The aim of this study was to explore if different PET tracers could be useful to image aneurysmal disease. METHODS AND RESULTS Human aneurysmal aortic tissue, collected during elective resection of abdominal aortic aneurysm (AAA) of asymptomatic patients, was investigated in vitro by means of autoradiography with [(68)Ga]CRP-binder targeting C-reactive protein, [(11)C]DAA1106 targeting translocator protein (18 kDa), [(11)C]D-deprenyl with unknown target receptor, [(11)C]deuterium-L-deprenyl targeting astrocytes, [(18)F]fluciclatide targeting integrin αVβ3, [(68)Ga]IMP461 and bi-specific antibody TF2 052107 targeting carcinoembryonic antigen, [(18)F]F-metomidate targeting mitochondrial cytochrome P-450 species in the adrenal cortex, and [(18)F]vorozole targeting aromatase. Of the investigated tracers, only [(18)F]fluciclatide exhibited specific binding, whereas the other PET tracers failed to show specific uptake in the investigated tissue and are probably not useful for the intended purpose. CONCLUSION It seems likely that αVβ3 integrin expression in AAA can be visualized with PET and that the αVβ3 selective tracer, [(18)F]fluciclatide, may be suitable for in vivo molecular imaging of asymptomatic AAA. Additional evaluation of [(18)F]fluciclatide and αVβ3 integrin expression in AAA will be performed in vitro as well as in vivo.
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Affiliation(s)
- Gustaf Tegler
- Department of Surgical Sciences, Section of Vascular Surgery, Uppsala University, Uppsala, Sweden
| | - Sergio Estrada
- Platform for Preclinical PET, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Håkan Hall
- Platform for Preclinical PET, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Anders Wanhainen
- Department of Surgical Sciences, Section of Vascular Surgery, Uppsala University, Uppsala, Sweden
| | - Martin Björck
- Department of Surgical Sciences, Section of Vascular Surgery, Uppsala University, Uppsala, Sweden
| | - Jens Sörensen
- Nuclear Medicine and PET, Department of Radiology and Oncology and Radiation Sciences, Uppsala University, Uppsala, Sweden
- PET Centre, Uppsala University, Uppsala, Sweden
| | - Gunnar Antoni
- Platform for Preclinical PET, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
- PET Centre, Uppsala University, Uppsala, Sweden
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Linnman C, Borsook D. Completing the Pain Circuit: Recent Advances in Imaging Pain and Inflammation beyond the Central Nervous System. Rambam Maimonides Med J 2013; 4:e0026. [PMID: 24228169 PMCID: PMC3820299 DOI: 10.5041/rmmj.10133] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
This review describes some of the recent developments in imaging aspects of pain in the periphery. It is now possible to image nerves in the cornea non-invasively, to image receptor level expression and inflammatory processes in injured tissue, to image nerves and alterations in nerve properties, to image astrocyte and glial roles in neuroinflammatory processes, and to image pain conduction functionally in the trigeminal ganglion. These advances will ultimately allow us to describe the pain pathway, from injury site to behavioral consequence, in a quantitative manner. Such a development could lead to diagnostics determining the source of pain (peripheral or central), objective monitoring of treatment progression, and, hopefully, objective biomarkers of pain.
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Affiliation(s)
- Clas Linnman
- Department of Anesthesiology, Perioperative and Pain Medicine, Boston Children's Hospital, Boston, Massachusetts, United States of America
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Abstract
Among various neuroimaging techniques used for the evaluation of children with intractable epilepsy, positron emission tomography (PET) employing various PET tracers plays a very important role, especially in localizing areas of focal cortical dysplasia. This is particularly important in infants, where incomplete myelination may limit the structural information provided by MRI. In children with tuberous sclerosis, PET can differentiate between epileptogenic and nonepileptogenic tubers, previously not thought to be possible with neuroimaging. PET may reveal cortical or subcortical abnormalities in various epilepsy syndromes, such as infantile spasms and Landau-Kleffner syndrome. Various other applications of PET have included the investigation of epileptic networks, secondary epileptic foci, dual pathology, and neuroinflammation. Finally, PET can also be used to evaluate various cognitive processes and their underlying neurological substrates and can help in addressing the issue of brain plasticity and reorganization, related to epilepsy.
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Affiliation(s)
- Ajay Kumar
- Departments of Pediatrics and Neurology, School of Medicine, Wayne State University, and PET Center, Children's Hospital of Michigan, Detroit, MI, USA
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Carter SF, Schöll M, Almkvist O, Wall A, Engler H, Långström B, Nordberg A. Evidence for astrocytosis in prodromal Alzheimer disease provided by 11C-deuterium-L-deprenyl: a multitracer PET paradigm combining 11C-Pittsburgh compound B and 18F-FDG. J Nucl Med 2012; 53:37-46. [PMID: 22213821 DOI: 10.2967/jnumed.110.087031] [Citation(s) in RCA: 290] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
UNLABELLED Astrocytes colocalize with fibrillar amyloid-β (Aβ) plaques in postmortem Alzheimer disease (AD) brain tissue. It is therefore of great interest to develop a PET tracer for visualizing astrocytes in vivo, enabling the study of the regional distribution of both astrocytes and fibrillar Aβ. A multitracer PET investigation was conducted for patients with mild cognitive impairment (MCI), patients with mild AD, and healthy controls using (11)C-deuterium-L-deprenyl ((11)C-DED) to measure monoamine oxidase B located in astrocytes. Along with (11)C-DED PET, (11)C-Pittsburgh compound B ((11)C-PIB; fibrillar Aβ deposition), (18)F-FDG (glucose metabolism), T1 MRI, cerebrospinal fluid, and neuropsychologic data were acquired from the patients. METHODS (11)C-DED PET was performed in MCI patients (n = 8; mean age ± SD, 62.6 ± 7.5 y; mean Mini Mental State Examination, 27.5 ± 2.1), AD patients (n = 7; mean age, 65.1 ± 6.3 y; mean Mini Mental State Examination, 24.4 ± 5.7), and healthy age-matched controls (n = 14; mean age, 64.7 ± 3.6 y). A modified reference Patlak model, with cerebellar gray matter as a reference, was chosen for kinetic analysis of the (11)C-DED data. (11)C-DED data from 20 to 60 min were analyzed using a digital brain atlas. Mean regional (18)F-FDG uptake and (11)C-PIB retention were calculated for each patient, with cerebellar gray matter as a reference. RESULTS ANOVA analysis of the regional (11)C-DED binding data revealed a significant group effect in the bilateral frontal and bilateral parietal cortices related to increased binding in the MCI patients. All patients, except 3 with MCI, showed high (11)C-PIB retention. Increased (11)C-DED binding in most cortical and subcortical regions was observed in MCI (11)C-PIB+ patients relative to controls, MCI (11)C-PIB (negative) patients, and AD patients. No regional correlations were found between the 3 PET tracers. CONCLUSION Increased (11)C-DED binding throughout the brain of the MCI (11)C-PIB+ patients potentially suggests that astrocytosis is an early phenomenon in AD development.
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Affiliation(s)
- Stephen F Carter
- Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
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Kumar A, Semah F, Chugani HT, Theodore WH. Epilepsy diagnosis: positron emission tomography. HANDBOOK OF CLINICAL NEUROLOGY 2012; 107:409-24. [PMID: 22938986 DOI: 10.1016/b978-0-444-52898-8.00026-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Ajay Kumar
- Department of Pediatrics & Neurology, Children's Hospital of Michigan, Detroit, MI, USA
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40
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The Assay of Enzyme Activity by Positron Emission Tomography. MOLECULAR IMAGING IN THE CLINICAL NEUROSCIENCES 2012. [DOI: 10.1007/7657_2012_53] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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41
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Abstract
Studies using positron emission tomography (PET) have advanced our pathophysiological and biochemical understanding of focal and generalized epilepsies. H(2) (15)O PET allows quantification of cerebral blood flow and (18)F-fluorodeoxyglucose-PET quantification of cerebral glucose metabolism. Neurotransmitters are directly responsible for modulating synaptic activity and newer PET tracers can provide information about synaptic activity and specific ligand-receptor relationships, which are important for epileptogenesis and the spread of epileptic activity.
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Affiliation(s)
- Matthias J Koepp
- National Hospital for Neurology and Neurosurgery, Queen Square, London, UK.
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Razifar P, Axelsson J, Schneider H, Långström B, Bengtsson E, Bergström M. A new application of pre-normalized principal component analysis for improvement of image quality and clinical diagnosis in human brain PET studies—Clinical brain studies using [11C]-GR205171, [11C]-l-deuterium-deprenyl, [11C]-5-Hydroxy-l-Tryptophan, [11C]-l-DOPA and Pittsburgh Compound-B. Neuroimage 2006; 33:588-98. [PMID: 16934493 DOI: 10.1016/j.neuroimage.2006.05.060] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2005] [Revised: 05/11/2006] [Accepted: 05/23/2006] [Indexed: 10/24/2022] Open
Abstract
Principal component analysis (PCA) is one of the most applied multivariate image analysis tool on dynamic Positron Emission Tomography (PET). Independent of used reconstruction methodologies, PET images contain correlation in-between pixels, correlations in-between frame and errors caused by the reconstruction algorithm including different corrections, which can affect the performance of the PCA. In this study, we have investigated a new approach of application of PCA on pre-normalized, dynamic human PET images. A range of different tracers have been used for this purpose to explore the performance of the new method as a way to improve detection and visualization of significant changes in tracer kinetics and to enhance the discrimination between pathological and healthy regions in the brain. We compare the new results with the results obtained using other methods. Images generated using the new approach contain more detailed anatomical information with higher quality, precision and visualization, compared with images generated using other methods.
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Affiliation(s)
- Pasha Razifar
- Uppsala University, Centre for Image Analysis, Lägerhyddsv. 3, SE-752 37 Uppsala, Sweden
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43
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Abstract
Over the past decade there have been many advances in data acquisition and analysis for structural and functional neuroimaging of people with epilepsy. New imaging sequences and analysis techniques have increased the resolution of images such that underlying structural pathology can be seen in many patients with "cryptogenic" epilepsy. When an epileptogenic lesion is present, antiepileptic drugs alone rarely prevent seizures. However, the success of surgical treatment is improved when a structural lesion has been identified. Lesions might not overlap with the area of the cortex generating seizures and may continue into areas sustaining normal functions. To prevent postsurgical morbidity, the spatial relation between functionally important areas and the epileptogenic lesion must be assessed before surgery. In this review we describe the potential of different neuroimaging techniques to show lesions, assess neuronal function, and assist with the prognosis of postsurgical outcome in patients with refractory focal epilepsy.
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Van Paesschen W. Qualitative and quantitative imaging of the hippocampus in mesial temporal lobe epilepsy with hippocampal sclerosis. Neuroimaging Clin N Am 2004; 14:373-400, vii. [PMID: 15324854 DOI: 10.1016/j.nic.2004.04.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
MR imaging allows the in vivo detection of hippocampal sclerosis (HS) and has been instrumental in the delineation of the syndrome of mesial temporal lobe epilepsy with HS (mTLE-HS). MR features of HS include hippocampal atrophy with an increased T2 signal. Quantitative MR imaging accurately reflects the degree of hippocampal damage.Ictal single photon emission computed tomography (SPECT) in mTLE-HS shows typical perfusion patterns of ipsilateral temporal lobe hyperperfusion, and ipsilateral frontoparietal and contralateral cerebellar hypoperfusion. Interictal 18fluoro-2-deoxyglucose positron emission tomography (PET) shows multiregional hypometabolism, involving predominantly the ipsilateral temporal lobe. 11C-flumazenil PET shows hippocampal decreases in central benzodiazepine receptor density. Future strategies to study the etiology and pathogenesis of HS should include longitudinal MR imaging studies,MR studies in families with epilepsy and febrile seizures, stratification for genetic background, coregistration with SPECT and PET, partial volume correction and statistical parametric mapping analysis of SPECT and PET images.
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Affiliation(s)
- Wim Van Paesschen
- Department of Neurology, University Hospital Gasthuisberg, Katholieke Universiteit Leuven, 49 Herestraat, 3000 Leuven, Belgium.
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45
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Hammers A. Flumazenil positron emission tomography and other ligands for functional imaging. Neuroimaging Clin N Am 2004; 14:537-51. [PMID: 15324863 DOI: 10.1016/j.nic.2004.04.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Most PET receptor studies in idiopathic generalized epilepsy conducted to date include only small numbers of patients and should be interpreted with caution. Differences between earlier and later studies can largely be explained by different inclusion criteria and improving methodology. The finding of some increase of GABAA receptor binding in IGE has a potential pathologic basis in microdysgenesis. Future studies aiming to elucidate the pathophysiology of IGEs may benefit from the use of subtype-specific opioid ligands, available now, and GABAB ligands, if and when they become available.
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Affiliation(s)
- Alexander Hammers
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, 33 Queen Square, London WC1N 3BG, UK.
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46
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Fowler JS, Volkow ND, Wang GJ, Ding YS. 2-deoxy-2-[18F]fluoro-d-glucose and alternative radiotracers for positron emission tomography imaging using the human brain as a model. Semin Nucl Med 2004; 34:112-21. [PMID: 15031811 DOI: 10.1053/j.semnuclmed.2004.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
2-deoxy-2-[18F]fluoro-D-glucose (18FDG) is now routinely available in many hospitals and other institutions either via on-site production or from one of the dozens of regional radiopharmacies worldwide. Its reliable production has opened the possibility for use in both basic and clinical investigations and also in pairing it with other more biologically specific positron emission tomography tracers to provide an important functional perspective to the measurement. In this article, we highlight examples in which 18FDG is paired with another carbon-11- or fluorine-18-labeled radiotracer in the same subject to correlate neurotransmitter-specific effects with regional metabolic effects using the human brain as a model. We describe studies that fall into three major areas: normal aging, neuropsychiatric disorders, and drug action.
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Affiliation(s)
- Joanna S Fowler
- Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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Trampal C, Engler H. [PET in neurology and psychiatry. II]. REVISTA ESPANOLA DE MEDICINA NUCLEAR 2002; 21:439-55; quiz 456-60. [PMID: 12425894 DOI: 10.1016/s0212-6982(02)72123-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- C Trampal
- Uppsala University PET Centre. Uppsala. Sweden.
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48
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Abstract
Positron emission tomography can be used for localization of epileptic foci, and preoperative functional mapping. Rapid improvements in magnetic resonance imaging, however, have restricted the need for positron emission tomography to a minority of patients who have unrevealing magnetic resonance imaging scans. Positron emission tomography will continue to be of value in investigations of the pathophysiology of seizure disorders.
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Affiliation(s)
- William H Theodore
- Clinical Epilepsy Section, National Institutes of Health, Bethesda, Maryland 20892, USA.
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