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Nisha Aji K, Cisbani G, Weidenauer A, Koppel A, Hafizi S, Da Silva T, Kiang M, Rusjan PM, Bazinet RP, Mizrahi R. Neurofilament light-chain (NfL) and 18 kDa translocator protein in early psychosis and its putative high-risk. Brain Behav Immun Health 2024; 37:100742. [PMID: 38495956 PMCID: PMC10940889 DOI: 10.1016/j.bbih.2024.100742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 12/27/2023] [Accepted: 02/15/2024] [Indexed: 03/19/2024] Open
Abstract
Evidence of elevated peripheral Neurofilament light-chain (NfL) as a biomarker of neuronal injury can be utilized to reveal nonspecific axonal damage, which could reflect altered neuroimmune function. To date, only a few studies have investigated NfL as a fluid biomarker in schizophrenia primarily, though none in its putative prodrome (Clinical High-Risk, CHR) or in untreated first-episode psychosis (FEP). Further, it is unknown whether peripheral NfL is associated with 18 kDa translocator protein (TSPO), a validated neuroimmune marker. In this secondary study, we investigated for the first time (1) serum NfL in early stages of psychosis including CHR and FEP as compared to healthy controls, and (2) examined its association with brain TSPO, using [18F]FEPPA positron emission tomography (PET). Further, in the exploratory analyses, we aimed to assess associations between serum NfL and symptom severity in patient group and cognitive impairment in the combined cohort. A large cohort of 84 participants including 27 FEP (24 antipsychotic-naive), 41 CHR (34 antipsychotic-naive) and 16 healthy controls underwent structural brain MRI and [18F]FEPPA PET scan and their blood samples were obtained and assessed for serum NfL concentrations. We found no significant differences in serum NfL levels across clinical groups, controlling for age. We also found no significant association between NfL levels and brain TSPO in the entire cohort. We observed a negative association between serum NfL and negative symptom severity in CHR. Our findings suggest that neither active neuroaxonal deterioration as measured with NfL nor associated neuroimmune activation (TSPO) is clearly identifiable in an early mostly untreated psychosis sample including its putative high-risk.
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Affiliation(s)
- Kankana Nisha Aji
- Department of Pharmacology & Toxicology, University of Toronto, Toronto, Ontario, Canada
- Douglas Research Centre, Clinical and Translational Sciences Lab, Montreal, Quebec, Canada
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Giulia Cisbani
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Ana Weidenauer
- Division of General Psychiatry, Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Vienna, Austria
| | - Alex Koppel
- Department of Pharmacology & Toxicology, University of Toronto, Toronto, Ontario, Canada
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Sina Hafizi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Tania Da Silva
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Michael Kiang
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Pablo M. Rusjan
- Douglas Research Centre, Clinical and Translational Sciences Lab, Montreal, Quebec, Canada
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | - Richard P. Bazinet
- Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Romina Mizrahi
- Douglas Research Centre, Clinical and Translational Sciences Lab, Montreal, Quebec, Canada
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec, Canada
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Ayilara GO, Owoyele BV. Neuroinflammation and microglial expression in brains of social-isolation rearing model of schizophrenia. IBRO Neurosci Rep 2023; 15:31-41. [PMID: 37359498 PMCID: PMC10285239 DOI: 10.1016/j.ibneur.2023.05.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 05/18/2023] [Accepted: 05/30/2023] [Indexed: 06/28/2023] Open
Abstract
Schizophrenia is a psychiatric disorder with a global prevalence of approximately 0.45%. It is considered a mental illness, with negative symptoms, positive symptoms, and cognitive dysfunction. The outcomes of studies on the role of microglia and neuroinflammation have been conflicting. In addition, there is a poor understanding of the sex differences in microglial expression and neuroinflammation markers in the prefrontal cortex, hippocampus, and nucleus accumbens. Understanding the exact roles of neuroinflammation may guide the development of efficient therapeutic drugs that can address the negative, positive, and cognitive symptoms of the disease. We examined the effect of social isolation rearing on schizophrenia-related behaviours in male and female BALB/c mice. The social-isolation rearing protocol started on post-natal day (PND) 21, lasting for 35 days. Animals were assigned to four cohorts, consisting of five animals per group. On PND 56, animals were assessed for behavioural changes. We used enzyme-linked immunosorbent assays to investigate the expression of nuclear factor kappa B (NF-κB), tumour necrosis factor-α (TNF-α), and Interleukin-1β (IL-1β) in the hippocampus, nucleus accumbens, and prefrontal cortex. Immunohistochemistry was used to assess the expression of microglia in the three brain regions. Our study showed that isolation rearing led to increasing locomotion, heightened anxiety, depression, and a reduced percentage of prepulse inhibition. There was a significant increase (p < 0.05) in anxiety in the female isolation mice compared to male isolation mice. Furthermore, isolation rearing significantly increased microglia count (p < 0.05) in the hippocampus, nucleus accumbens, and prefrontal cortex, only in the male group. There was microglial hyper-activation as evident in the downregulation of CX3CR1 in both male and female social-isolation groups. Male social-isolation mice showed a significant increase (p < 0.05) in neuroinflammation markers only in the nucleus accumbens while the female social-isolation mice showed a significant increase (p < 0.05) in neuroinflammation markers in both the nucleus accumbens and hippocampus. The study showed that therapeutic interventions aimed at modulating CX3CR1 activity and reducing inflammation may be beneficial for patients with schizophrenia.
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Nisha Aji K, Hafizi S, Da Silva T, Kiang M, Rusjan PM, Weickert CS, Mizrahi R. Interaction between peripheral and central immune markers in clinical high risk for psychosis. Brain Behav Immun Health 2023; 30:100636. [PMID: 37293440 PMCID: PMC10244662 DOI: 10.1016/j.bbih.2023.100636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 05/07/2023] [Indexed: 06/10/2023] Open
Abstract
Neuroinflammatory events prior to the diagnosis of schizophrenia may play a role in transition to illness. To date only one in-vivo study has investigated this association between peripheral proinflammatory cytokines and brain markers of inflammation (e.g., mitochondrial 18 kDa translocator protein, TSPO) in schizophrenia, but none in its putative prodrome. In this study, we primarily aimed to (Barron et al., 2017) test study group (clinical high-risk (CHR) and healthy controls) differences in peripheral inflammatory markers and test for any associations with symptom measures, (Hafizi et al., 2017a) investigate the interaction between brain TSPO levels (dorsolateral prefrontal cortex (DLPFC) and hippocampus) and peripheral inflammatory clusters (entire cohort and (CHR) group independently) within a relatively large group of individuals at CHR for psychosis (N = 38) and healthy controls (N = 20). Participants underwent structural brain magnetic resonance imaging (MRI) and TSPO [18F]FEPPA positron emission tomography (PET) scans. Serum samples were assessed for peripheral inflammatory markers (i.e., CRP and interleukins). For exploratory analysis, we aimed to examine cluster differences for symptom measures and identify independent peripheral predictors of brain TSPO expression. Here, we report increased IL-8 levels that are positively correlated with prodromal general symptom severity and showed trend-level association with apathy in CHR. We identified distinct inflammatory clusters characterized by inflammatory markers (IL-1 β, IL-2, IFN-γ) that were comparable between entire cohort and CHR. TSPO levels did not differ between inflammatory clusters (entire cohort or CHR). Finally, we show that CRP, IL-1 β, TNF-α, and IFN-γ levels were the independent peripheral predictors of brain TSPO expression. Thus, alterations in brain TSPO expression in response to inflammatory processes are not evident in CHR. Taken together, clustering by inflammatory status is a promising strategy to characterize the interaction between brain TSPO and peripheral markers of inflammation.
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Affiliation(s)
- Kankana Nisha Aji
- Department of Pharmacology & Toxicology, University of Toronto, Toronto, Ontario, Canada
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Douglas Research Centre, Clinical and Translational Sciences Lab, Montreal, Quebec, Canada
| | - Sina Hafizi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Psychiatry, Rady Faculty of Health Sciences, Max Rady College of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Tania Da Silva
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Michael Kiang
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Pablo M. Rusjan
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Douglas Research Centre, Clinical and Translational Sciences Lab, Montreal, Quebec, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | | | - Romina Mizrahi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
- Douglas Research Centre, Clinical and Translational Sciences Lab, Montreal, Quebec, Canada
- Department of Psychiatry, McGill University, Montreal, Quebec, Canada
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Mamah D. A Review of Potential Neuroimaging Biomarkers of Schizophrenia-Risk. JOURNAL OF PSYCHIATRY AND BRAIN SCIENCE 2023; 8:e230005. [PMID: 37427077 PMCID: PMC10327607 DOI: 10.20900/jpbs.20230005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
The risk for developing schizophrenia is increased among first-degree relatives of those with psychotic disorders, but the risk is even higher in those meeting established criteria for clinical high risk (CHR), a clinical construct most often comprising of attenuated psychotic experiences. Conversion to psychosis among CHR youth has been reported to be about 15-35% over three years. Accurately identifying individuals whose psychotic symptoms will worsen would facilitate earlier intervention, but this has been difficult to do using behavior measures alone. Brain-based risk markers have the potential to improve the accuracy of predicting outcomes in CHR youth. This narrative review provides an overview of neuroimaging studies used to investigate psychosis risk, including studies involving structural, functional, and diffusion imaging, functional connectivity, positron emission tomography, arterial spin labeling, magnetic resonance spectroscopy, and multi-modality approaches. We present findings separately in those observed in the CHR state and those associated with psychosis progression or resilience. Finally, we discuss future research directions that could improve clinical care for those at high risk for developing psychotic disorders.
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Affiliation(s)
- Daniel Mamah
- Department of Psychiatry, Washington University Medical School, St. Louis, MO, 63110, USA
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Mawson ER, Morris BJ. A consideration of the increased risk of schizophrenia due to prenatal maternal stress, and the possible role of microglia. Prog Neuropsychopharmacol Biol Psychiatry 2023; 125:110773. [PMID: 37116354 DOI: 10.1016/j.pnpbp.2023.110773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 04/07/2023] [Accepted: 04/18/2023] [Indexed: 04/30/2023]
Abstract
Schizophrenia is caused by interaction of a combination of genetic and environmental factors. Of the latter, prenatal exposure to maternal stress is reportedly associated with elevated disease risk. The main orchestrators of inflammatory processes within the brain are microglia, and aberrant microglial activation/function has been proposed to contribute to the aetiology of schizophrenia. Here, we evaluate the epidemiological and preclinical evidence connecting prenatal stress to schizophrenia risk, and consider the possible mediating role of microglia in the prenatal stress-schizophrenia relationship. Epidemiological findings are rather consistent in supporting the association, albeit they are mitigated by effects of sex and gestational timing, while the evidence for microglial activation is more variable. Rodent models of prenatal stress generally report lasting effects on offspring neurobiology. However, many uncertainties remain as to the mechanisms underlying the influence of maternal stress on the developing foetal brain. Future studies should aim to characterise the exact processes mediating this aspect of schizophrenia risk, as well as focussing on how prenatal stress may interact with other risk factors.
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Affiliation(s)
- Eleanor R Mawson
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Brian J Morris
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
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Minocycline Ameliorates Chronic Unpredictable Mild Stress-Induced Neuroinflammation and Abnormal mPFC-HIPP Oscillations in Mice. Mol Neurobiol 2022; 59:6874-6895. [PMID: 36048340 DOI: 10.1007/s12035-022-03018-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/24/2022] [Indexed: 10/14/2022]
Abstract
Stress-induced neuroinflammation is a hallmark of modern society and has been linked to various emotional disorders, including anxiety. However, how microglia-associated neuroinflammation under chronic unpredictable mild stress (CUMS) alters mitochondrial function and subsequent medial prefrontal cortex-hippocampus (mPFC-HIPP) connectivity remains obscure. We speculated that CUMS might induce neuroinflammation, which involves altered mitochondrial protein levels, blockade of neuroinflammation by a microglial modulator, minocycline, protects against CUMS-induced alterations. Mice were exposed to CUMS for 3 weeks and received minocycline (50 mg/kg) intraperitoneally for 7 consecutive days during the 3rd week of CUMS. Novelty-suppressed feeding test and contextual anxiety test assessed anxiety-like behavior. Western blotting and immunofluorescent staining were employed to evaluate levels of proteins involved in neuroinflammation and mitochondrial function. In vivo dual-site extracellular recordings of local field potential (LFP) were conducted to evaluate the oscillatory activity and brain connectivity in mPFC-HIPP circuitry. We show that CUMS results in excessive microglial activation accompanied by aberrant levels of mitochondrial proteins, such as ATP-5A and the fission protein, Drp-1, increased oxidative stress indicated by elevated levels of nitrotyrosine, and decreased Nrf-2 levels. Furthermore, CUMS causes downregulation of α1 subunit of GABAAR, vesicular GABA transporter (Vgat), and glutamine synthetase (GS), leading to impaired LFP and connectivity of the mPFC-HIPP circuitry. Strikingly, blockage of microglial activation by minocycline ameliorates CUMS-induced aberrant levels of mitochondrial and GABAergic signaling proteins and prevents CUMS-induced anxiety-like behavior in mice. To the end, the study revealed that microglia is critically involved in stress-induced neuroinflammation, which may underlie the molecular mechanism of CUMS-induced anxiety behavior.
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In vivo imaging translocator protein (TSPO) in autism spectrum disorder. Neuropsychopharmacology 2022; 47:1421-1427. [PMID: 35383319 PMCID: PMC9117200 DOI: 10.1038/s41386-022-01306-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 03/01/2022] [Accepted: 03/07/2022] [Indexed: 12/23/2022]
Abstract
Converging evidence points to the significant involvement of the immune system in autism spectrum disorders (ASD). Positron emission tomography (PET) can quantify translocator protein 18 kDa (TSPO), a marker with increased expression mainly in microglia and, to some extent astroglia during neuropsychiatric diseases with inflammation. This preliminary analysis explored, for the first time, whether TSPO binding was altered in male and female participants with ASD in vivo using full kinetic quantification. Thirteen individuals with ASD (IQ > 70 [n = 12], IQ = 62 [n = 1]), 5 F, 25 ± 5 years) were scanned with [18F]FEPPA PET. Data from 13 typically developing control participants with matching age and TSPO rs6971 polymorphism (9 F, age 24 ± 5 years) were chosen from previous studies for comparison. The two tissue compartment model (2TCM) was used to determine the total volume of distribution ([18F]FEPPA VT) in four previously identified regions of interest (ROI): prefrontal, temporal, cerebellar, and anterior cingulate cortices. We observe no significant difference in [18F]FEPPA VT relative to controls (F(1,26)= 1.74, p = 0.20). However, 2 ASD participants with higher VT had concurrent major depressive episodes (MDE), which has been consistently reported during MDE. After excluding those 2 ASD participants, in a post-hoc analysis, our results show lower [18F]FEPPA VT in ASD participants compared to controls (F(1,24)= 6.62, p = 0.02). This preliminary analysis provides evidence suggesting an atypical neuroimmune state in ASD.
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De Picker LJ, Haarman BCM. Applicability, potential and limitations of TSPO PET imaging as a clinical immunopsychiatry biomarker. Eur J Nucl Med Mol Imaging 2021; 49:164-173. [PMID: 33735406 DOI: 10.1007/s00259-021-05308-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 03/08/2021] [Indexed: 02/08/2023]
Abstract
PURPOSE TSPO PET imaging may hold promise as a single-step diagnostic work-up for clinical immunopsychiatry. This review paper on the clinical applicability of TSPO PET for primary psychiatric disorders discusses if and why TSPO PET imaging might become the first clinical immunopsychiatry biomarker and the investment prerequisites and scientific advancements needed to accommodate this transition from bench to bedside. METHODS We conducted a systematic search of the literature to identify clinical studies of TSPO PET imaging in patients with primary psychiatric disorders. We included both original case-control studies as well as longitudinal cohort studies of patients with a primary psychiatric diagnosis. RESULTS Thirty-one original studies met our inclusion criteria. In the field of immunopsychiatry, TSPO PET has until now mostly been studied in schizophrenia and related psychotic disorders, and to a lesser extent in mood disorders and neurodevelopmental disorders. Quantitative TSPO PET appears most promising as a predictive biomarker for the transdiagnostic identification of subgroups or disease stages that could benefit from immunological treatments, or as a prognostic biomarker forecasting patients' illness course. Current scanning protocols are still too unreliable, impractical and invasive for clinical use in symptomatic psychiatric patients. CONCLUSION TSPO PET imaging in its present form does not yet offer a sufficiently attractive cost-benefit ratio to become a clinical immunopsychiatry biomarker. Its translation to psychiatric clinical practice will depend on the prioritising of longitudinal research and the establishment of a uniform protocol rendering clinically meaningful TSPO uptake quantification at the shortest possible scan duration without arterial cannulation.
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Affiliation(s)
- Livia J De Picker
- University Psychiatric Hospital Campus Duffel, Stationsstraat 22C, 2570, Duffel, Belgium.
- Collaborative Antwerp Psychiatric Research Institute, University of Antwerp, Wilrijkstraat 1, 2650, Edegem, Belgium.
| | - Benno C M Haarman
- Department of Psychiatry, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9700RA, Groningen, The Netherlands
- Rob Giel Research Center (RGOc), University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9700RA, Groningen, The Netherlands
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Da Silva T, Guma E, Hafizi S, Koppel A, Rusjan P, Kennedy JL, Chakravarty MM, Mizrahi R. Genetically Predicted Brain C4A Expression Is Associated With TSPO and Hippocampal Morphology. Biol Psychiatry 2021; 90:652-660. [PMID: 34456009 DOI: 10.1016/j.biopsych.2021.06.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 06/27/2021] [Accepted: 06/28/2021] [Indexed: 01/18/2023]
Abstract
BACKGROUND Alterations in the immune system, particularly C4A, have been implicated in the pathophysiology of schizophrenia. C4A promotes synapse elimination by microglia in preclinical models; however, it is unknown whether this process is also present in living humans and how it affects brain morphology. METHODS Participants (N = 111; 33 patients with psychosis, 37 individuals at clinical high risk, and 41 healthy control subjects) underwent a TSPO [18F]FEPPA positron emission tomography scan and a magnetic resonance imaging scan. Brain C4A expression was genetically predicted as a function of the dosage of each of 4 structural elements (C4AL, C4BL, C4AS, C4BS). RESULTS Higher genetically predicted brain C4A expression was associated with higher brain microglial marker (TSPO) and altered hippocampal morphology, including reduced surface area and medial displacement in the CA1 area. This study is the first to quantify genetically predicted brain C4A expression in individuals at clinical high risk, showing significantly lower C4A in individuals at clinical high risk compared with healthy control subjects. We also showed a robust effect of sex on genetically predicted brain C4A expression and effects of both sex and cannabis use on brain TSPO. CONCLUSIONS This study shows for the first time complement system (C4A) coupling with a microglial marker (TSPO) and hippocampal morphology in living human brain. These findings pave the way for future research on the interaction between C4A and glial cell function, which has the potential to inform the disease mechanism underlying psychosis and schizophrenia.
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Affiliation(s)
- Tania Da Silva
- Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Elisa Guma
- Computational Brain Anatomy Laboratory, Montreal, Quebec, Canada; Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada
| | - Sina Hafizi
- Department of Psychiatry, Rady Faculty of Health Sciences, Max Rady College of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Alex Koppel
- Department of Pharmacology & Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Pablo Rusjan
- Cerebral Imaging Center, Douglas Mental Health University Institute, Montreal, Quebec, Canada; Department of Psychiatry, McGill University, Montreal, Quebec, Canada
| | - James L Kennedy
- Tanenbaum Centre for Pharmacogenetics, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Mallar M Chakravarty
- Cerebral Imaging Center, Douglas Mental Health University Institute, Montreal, Quebec, Canada; Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada; Department of Psychiatry, McGill University, Montreal, Quebec, Canada; Department of Biological and Biomedical Engineering, McGill University, Montreal, Quebec, Canada
| | - Romina Mizrahi
- Cerebral Imaging Center, Douglas Mental Health University Institute, Montreal, Quebec, Canada; Integrated Program in Neuroscience, McGill University, Montreal, Quebec, Canada; Department of Psychiatry, McGill University, Montreal, Quebec, Canada.
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Rigney G, Ayubcha C, Werner TJ, Alavi A, Revheim ME. The utility of PET imaging in the diagnosis and management of psychosis: a brief review. Clin Transl Imaging 2021. [DOI: 10.1007/s40336-021-00466-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Abstract
Purpose
Advances in the pathophysiological characterization of psychosis has led to a newfound role of biomarkers in diagnostic and prognostic contexts. Further, advances in the accuracy and sensitivity of nuclear medicine imaging techniques, and specifically positron emission tomography (PET), have improved the ability to diagnose and manage individuals experiencing first-episode psychosis or those at greater risk for developing psychosis.
Methods
Literature searches were performed in PubMed, Google Scholar, and Web of Science to identify papers related to the use of PET imaging in the diagnosis or management of psychosis. Search terms used included “positron emission tomography”, “PET imaging”, “psychosis”, “disorders of psychosis”, “schizophrenia”, “biomarkers”, “diagnostic biomarkers”, “prognostic biomarker”, “monitoring biomarker”, “outcome biomarker”, and “predictive biomarker.”
Results
Studies included fell into three categories: those examining microglia, those studying dopamine synthesis capacity, and those examining acetylcholine receptor activity. Microglial imaging has been shown to be ineffective in all patients with psychosis, but some believe it shows promise in a subset of patients with psychosis, although no defining characteristics of said subset have been postulated. Studies of dopamine synthesis capacity suggest that presynaptic dopamine is reliably elevated in patients with psychosis, but levels of dopamine active transporter are not. Further, positron emission tomography (PET) with [18F]fluoro-l-dihydroxyphenylalanine ([18F]FDOPA)-PET has been recently used successfully as a predictive biomarker of dopaminergic treatment response, although more work is needed to validate such findings. Finally, existing studies have also documented lower levels of binding to the α7 nicotinic cholinergic receptor (α7-nAChR) via [18F]-ASEM PET in patients with psychosis, however there is a dearth of prospective, randomized studies evaluating the efficacy of [18F]-ASEM as a diagnostic or monitoring biomarker of any kind.
Conclusion
Molecular imaging has become a useful tool in the diagnosis and management of psychosis. Further work must be done to improve the comparative prognostic value and diagnostic accuracy of different radiotracers.
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De Picker LJ, Victoriano GM, Richards R, Gorvett AJ, Lyons S, Buckland GR, Tofani T, Norman JL, Chatelet DS, Nicoll JAR, Boche D. Immune environment of the brain in schizophrenia and during the psychotic episode: A human post-mortem study. Brain Behav Immun 2021; 97:319-327. [PMID: 34339805 PMCID: PMC8475749 DOI: 10.1016/j.bbi.2021.07.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 07/22/2021] [Accepted: 07/24/2021] [Indexed: 02/05/2023] Open
Abstract
A causal relationship between immune dysregulation and schizophrenia has been supported by genome-wide association studies and epidemiological evidence. It remains unclear to what extent the brain immune environment is implicated in this hypothesis. We investigated the immunophenotype of microglia and the presence of perivascular macrophages and T lymphocytes in post-mortem brain tissue. Dorsal prefrontal cortex of 40 controls (22F:18M) and 37 (10F:27M) schizophrenia cases, of whom 16 had active psychotic symptoms at the time of death, was immunostained for seven markers of microglia (CD16, CD32a, CD64, CD68, HLA-DR, Iba1 and P2RY12), two markers for perivascular macrophages (CD163 and CD206) and T-lymphocytes (CD3). Automated quantification was blinded to the case designation and performed separately on the grey and white matter. 3D reconstruction of Iba1-positive microglia was performed in selected cases. An increased cortical expression of microglial Fcγ receptors (CD64 F = 7.92, p = 0.007; CD64/HLA-DR ratio F = 5.02, p = 0.029) highlights the importance of communication between the central and peripheral immune systems in schizophrenia. Patients in whom psychotic symptoms were present at death demonstrated an age-dependent increase of Iba1 and increased CD64/HLA-DR ratios relative to patients without psychotic symptoms. Microglia in schizophrenia demonstrated a primed/reactive morphology. A potential role for T-lymphocytes was observed, but we did not confirm the presence of recruited macrophages in the brains of schizophrenia patients. Taking in account the limitations of a post-mortem study, our findings support the hypothesis of an alteration of the brain immune environment in schizophrenia, with symptomatic state- and age-dependent effects.
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Affiliation(s)
- Livia J De Picker
- Collaborative Antwerp Psychiatric Research Institute, University of Antwerp, Antwerp, Belgium; University Psychiatric Department Campus Duffel, Duffel, Belgium
| | - Gerardo Mendez Victoriano
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Rhys Richards
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Alexander J Gorvett
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Simeon Lyons
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - George R Buckland
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK
| | - Tommaso Tofani
- Psychiatry Unit, Health Science Department, University of Florence, Florence, Italy
| | - Jeanette L Norman
- Histochemistry Research Unit, Clinical and Experimental Sciences, Faculty of Medicine University of Southampton, Southampton, UK
| | - David S Chatelet
- Biomedical Imaging Unit, Southampton General Hospital, University of Southampton, Southampton, UK
| | - James A R Nicoll
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK; Department of Cellular Pathology, University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | - Delphine Boche
- Clinical Neurosciences, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK.
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Rahimian R, Wakid M, O'Leary LA, Mechawar N. The emerging tale of microglia in psychiatric disorders. Neurosci Biobehav Rev 2021; 131:1-29. [PMID: 34536460 DOI: 10.1016/j.neubiorev.2021.09.023] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 08/18/2021] [Accepted: 09/08/2021] [Indexed: 12/24/2022]
Abstract
As the professional phagocytes of the brain, microglia orchestrate the immunological response and play an increasingly important role in maintaining homeostatic brain functions. Microglia are activated by pathological events or slight alterations in brain homeostasis. This activation is dependent on the context and type of stressor or pathology. Through secretion of cytokines, chemokines and growth factors, microglia can strongly influence the response to a stressor and can, therefore, determine the pathological outcome. Psychopathologies have repeatedly been associated with long-lasting priming and sensitization of cerebral microglia. This review focuses on the diversity of microglial phenotype and function in health and psychiatric disease. We first discuss the diverse homeostatic functions performed by microglia and then elaborate on context-specific spatial and temporal microglial heterogeneity. Subsequently, we summarize microglia involvement in psychopathologies, namely major depressive disorder, schizophrenia and bipolar disorder, with a particular focus on post-mortem studies. Finally, we postulate microglia as a promising novel therapeutic target in psychiatry through antidepressant and antipsychotic treatment.
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Affiliation(s)
- Reza Rahimian
- McGill Group for Suicide Studies, Douglas Mental Health University Institute, Verdun, QC, Canada
| | - Marina Wakid
- McGill Group for Suicide Studies, Douglas Mental Health University Institute, Verdun, QC, Canada; Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Liam Anuj O'Leary
- McGill Group for Suicide Studies, Douglas Mental Health University Institute, Verdun, QC, Canada; Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada
| | - Naguib Mechawar
- McGill Group for Suicide Studies, Douglas Mental Health University Institute, Verdun, QC, Canada; Integrated Program in Neuroscience, McGill University, Montreal, QC, Canada; Department of Psychiatry, McGill University, Montreal, QC, Canada.
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13
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Rathitharan G, Truong J, Tong J, McCluskey T, Meyer JH, Mizrahi R, Warsh J, Rusjan P, Kennedy JL, Houle S, Kish SJ, Boileau I. Microglia imaging in methamphetamine use disorder: a positron emission tomography study with the 18 kDa translocator protein radioligand [F-18]FEPPA. Addict Biol 2021; 26:e12876. [PMID: 32017280 DOI: 10.1111/adb.12876] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/08/2020] [Accepted: 01/12/2020] [Indexed: 01/19/2023]
Abstract
Activation of brain microglial cells, microgliosis, has been linked to methamphetamine (MA)-seeking behavior, suggesting that microglia could be a new therapeutic target for MA use disorder. Animal data show marked brain microglial activation following acute high-dose MA, but microglial status in human MA users is uncertain, with one positron emission tomography (PET) investigation reporting massively and globally increased translocator protein 18 kDa (TSPO; [C-11](R)-PK11195) binding, a biomarker for microgliosis, in MA users. Our aim was to measure binding of a second-generation TSPO radioligand, [F-18]FEPPA, in brain of human chronic MA users. Regional total volume of distribution (VT ) of [F-18]FEPPA was estimated with a two-tissue compartment model with arterial plasma input function for 10 regions of interest in 11 actively using MA users and 26 controls. A RM-ANOVA corrected for TSPO rs6971 polymorphism was employed to test significance. There was no main effect of group on [F-18]FEPPA VT (P = .81). No significant correlations between [F-18]FEPPA VT and MA use duration, weekly dosage, blood MA concentrations, regional brain volumes, and self-reported craving were observed. Our preliminary findings, consistent with our earlier postmortem data, do not suggest substantial brain microgliosis in MA use disorder but do not rule out microglia as a therapeutic target in MA addiction. Absence of increased [F-18]FEPPA TSPO binding might be related to insufficient MA dose or blunting of microglial response following repeated MA exposure, as suggested by some animal data.
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Affiliation(s)
- Gausiha Rathitharan
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Institute of Medical Sciences University of Toronto Toronto Ontario Canada
| | - Jennifer Truong
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Institute of Medical Sciences University of Toronto Toronto Ontario Canada
| | - Junchao Tong
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
| | - Tina McCluskey
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
| | - Jeffrey H. Meyer
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
- Department of Pharmacology and Toxicology University of Toronto Toronto Ontario Canada
- Institute of Medical Sciences University of Toronto Toronto Ontario Canada
| | - Romina Mizrahi
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
- Department of Pharmacology and Toxicology University of Toronto Toronto Ontario Canada
- Institute of Medical Sciences University of Toronto Toronto Ontario Canada
| | - Jerry Warsh
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
- Department of Pharmacology and Toxicology University of Toronto Toronto Ontario Canada
- Institute of Medical Sciences University of Toronto Toronto Ontario Canada
| | - Pablo Rusjan
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Pharmacology and Toxicology University of Toronto Toronto Ontario Canada
- Institute of Medical Sciences University of Toronto Toronto Ontario Canada
| | - James L. Kennedy
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
- Institute of Medical Sciences University of Toronto Toronto Ontario Canada
| | - Sylvain Houle
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
| | - Stephen J. Kish
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
- Department of Pharmacology and Toxicology University of Toronto Toronto Ontario Canada
- Institute of Medical Sciences University of Toronto Toronto Ontario Canada
| | - Isabelle Boileau
- Research Imaging Centre Centre for Addiction and Mental Health Toronto Ontario Canada
- Campbell Mental Health Research Institute Centre for Addiction and Mental Health Toronto Ontario Canada
- Department of Psychiatry University of Toronto Toronto Ontario Canada
- Institute of Medical Sciences University of Toronto Toronto Ontario Canada
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14
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Personality traits in psychosis and psychosis risk linked to TSPO expression: a neuroimmune marker. PERSONALITY NEUROSCIENCE 2020; 3:e14. [PMID: 33354652 PMCID: PMC7737185 DOI: 10.1017/pen.2020.14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 08/19/2020] [Accepted: 08/25/2020] [Indexed: 12/23/2022]
Abstract
Personality has been correlated with differences in cytokine expression, an indicator of peripheral inflammation; however, the associations between personality and central markers of inflammation have never been investigated in vivo in humans. Microglia are the resident macrophages of the central nervous system, and the first responders to tissue damage and brain insult. Microglial activation is associated with elevated expression of translocator protein 18kDa (TSPO), which can be imaged with positron emission tomography (PET) to quantify immune activation in the human brain. This study aimed to investigate the association between personality and TSPO expression across the psychosis spectrum. A total of 61 high-resolution [18F]FEPPA PET scans were conducted in 28 individuals at clinical high risk (CHR) for psychosis, 19 First-Episode Psychosis (FEP), and 14 healthy volunteers (HVs), and analyzed using a two-tissue compartment model and plasma input function to obtain a total volume of distribution (VT) as an index of brain TSPO expression (controlling for the rs6971 TSPO polymorphism). Personality was assessed using the Revised NEO Personality Inventory (NEO-PI-R). We found TSPO expression to be specifically associated with neuroticism. A positive association between TSPO expression and neuroticism was found in HVs, in contrast to a nonsignificant, negative association in CHR and significant negative association in FEP. The TSPO-associated neuroticism trait indicates an unexplored connection between neuroimmune activation and personality that varies across the psychosis spectrum.
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15
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Dinesh AA, Islam J, Khan J, Turkheimer F, Vernon AC. Effects of Antipsychotic Drugs: Cross Talk Between the Nervous and Innate Immune System. CNS Drugs 2020; 34:1229-1251. [PMID: 32975758 DOI: 10.1007/s40263-020-00765-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/29/2020] [Indexed: 12/11/2022]
Abstract
Converging lines of evidence suggest that activation of microglia (innate immune cells in the central nervous system [CNS]) is present in a subset of patients with schizophrenia. The extent to which antipsychotic drug treatment contributes to or combats this effect remains unclear. To address this question, we reviewed the literature for evidence that antipsychotic exposure influences brain microglia as indexed by in vivo neuroimaging and post-mortem studies in patients with schizophrenia and experimental animal models. We found no clear evidence from clinical studies for an effect of antipsychotics on either translocator protein (TSPO) radioligand binding (an in vivo neuroimaging measure of putative gliosis) or markers of brain microglia in post-mortem studies. In experimental animals, where drug and illness effects may be differentiated, we also found no clear evidence for consistent effects of antipsychotic drugs on TSPO radioligand binding. By contrast, we found evidence that chronic antipsychotic exposure may influence central microglia density and morphology. However, these effects were dependent on the dose and duration of drug exposure and whether an immune stimulus was present or not. In the latter case, antipsychotics were generally reported to suppress expression of inflammatory cytokines and inducible inflammatory enzymes such as cyclooxygenase and microglia activation. No clear conclusions could be drawn with regard to any effect of antipsychotics on brain microglia from current clinical data. There is evidence to suggest that antipsychotic drugs influence brain microglia in experimental animals, including possible anti-inflammatory actions. However, we lack detailed information on how these drugs influence brain microglia function at the molecular level. The clinical relevance of the animal data with regard to beneficial treatment effects and detrimental side effects of antipsychotic drugs also remains unknown, and further studies are warranted.
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Affiliation(s)
- Ayushi Anna Dinesh
- School of Medicine, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Juned Islam
- School of Medicine, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Javad Khan
- School of Medicine, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Federico Turkheimer
- Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Centre for Neuroimaging Sciences, De Crespigny Park, London, SE5 8AF, United Kingdom
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, SE1 1UL, United Kingdom
| | - Anthony C Vernon
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, SE1 1UL, United Kingdom.
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, 5 Cutcombe Road, London, SE5 9RT, United Kingdom.
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16
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Rooney S, Sah A, Unger MS, Kharitonova M, Sartori SB, Schwarzer C, Aigner L, Kettenmann H, Wolf SA, Singewald N. Neuroinflammatory alterations in trait anxiety: modulatory effects of minocycline. Transl Psychiatry 2020; 10:256. [PMID: 32732969 PMCID: PMC7393101 DOI: 10.1038/s41398-020-00942-y] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 07/07/2020] [Accepted: 07/15/2020] [Indexed: 02/04/2023] Open
Abstract
High trait anxiety is a substantial risk factor for developing anxiety disorders and depression. While neuroinflammation has been identified to contribute to stress-induced anxiety, little is known about potential dysregulation in the neuroinflammatory system of genetically determined pathological anxiety or high trait anxiety individuals. We report microglial alterations in various brain regions in a mouse model of high trait anxiety (HAB). In particular, the dentate gyrus (DG) of the hippocampus of HABs exhibited enhanced density and average cell area of Iba1+, and density of phagocytic (CD68+/Iba1+) microglia compared to normal anxiety (NAB) controls. Minocycline was used to assess the capacity of a putative microglia 'inhibitor' in modulating hyperanxiety behavior of HABs. Chronic oral minocycline indeed reduced HAB hyperanxiety, which was associated with significant decreases in Iba1+ and CD68+Iba1+ cell densities in the DG. Addressing causality, it was demonstrated that longer (10 days), but not shorter (5 days), periods of minocycline microinfusions locally into the DG of HAB reduced Iba-1+ cell density and attenuated hyperanxiety-related behavior, indicating that neuroinflammation in the DG is at least partially involved in the maintenance of pathological anxiety. The present data reveal evidence of disturbances in the microglial system of individuals with high trait anxiety. Minocycline attenuated HAB hyperanxiety, likely by modulation of microglial activity within the DG. Thus, the present data suggest that drugs with microglia-targeted anti-inflammatory properties could be promising as novel alternative or complimentary anxiolytic therapeutic approaches in specific subgroups of individuals genetically predisposed to hyperanxiety.
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Affiliation(s)
- Sinead Rooney
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck, Austria
| | - Anupam Sah
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck, Austria
| | - Michael S Unger
- Institute of Molecular Regenerative Medicine, Paracelsus Medical University, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center Salzburg (SCI-TReCS), Paracelsus Medical University, Salzburg, Austria
| | - Maria Kharitonova
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck, Austria
| | - Simone B Sartori
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck, Austria
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Ludwig Aigner
- Institute of Molecular Regenerative Medicine, Paracelsus Medical University, Salzburg, Austria
- Spinal Cord Injury and Tissue Regeneration Center Salzburg (SCI-TReCS), Paracelsus Medical University, Salzburg, Austria
| | - Helmut Kettenmann
- Department of Cellular Neurosciences, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Susanne A Wolf
- Department of Cellular Neurosciences, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Ophthalmology, Charité Universitätsmedizin, Berlin, Germany
| | - Nicolas Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Innsbruck, Austria.
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17
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Berdyyeva T, Xia C, Taylor N, He Y, Chen G, Huang C, Zhang W, Kolb H, Letavic M, Bhattacharya A, Szardenings AK. PET Imaging of the P2X7 Ion Channel with a Novel Tracer [ 18F]JNJ-64413739 in a Rat Model of Neuroinflammation. Mol Imaging Biol 2020; 21:871-878. [PMID: 30632003 DOI: 10.1007/s11307-018-01313-2] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE The P2X7 receptor, an adenosine triphosphate (ATP)-gated purinoreceptor, has emerged as one of the key players in neuroinflammatory processes. Therefore, developing a positron emission tomography (PET) tracer for imaging of P2X7 receptors in vivo presents a promising approach to diagnose, monitor, and study neuroinflammation in a variety of brain disorders. To fulfill the goal of developing a P2X7 PET ligand as a biomarker of neuroinflammation, [18F]JNJ-64413739 has been recently disclosed. PROCEDURES We evaluated [18F]JNJ-64413739 in a rat model of neuroinflammation induced by an intracerebral injection of lipopolysaccharide (LPS). In vivo brain uptake was determined by PET imaging. Upregulation of neuroinflammatory biomarkers was determined by quantitative polymerase chain reaction (qPCR). Distribution of the tracer in the brain was determined by ex vivo autoradiography (ARG). The specificity of [18F]JNJ-64413739 was confirmed by performing blocking experiments with the P2X7 antagonist JNJ-54175446. RESULTS Brain regions of rats injected with LPS had a significantly increased uptake (34 % ± 3 % s.e.m., p = 0.036, t test, standardized uptake value measured over the entire scanning period) of [18F]JNJ-64413739 relative to the corresponding brain regions of control animals injected with phosphate-buffered saline (PBS). The uptake in the contralateral regions and cerebellum was not significantly different between the groups of animals. The increase in uptake of [18F]JNJ-64413739 at the LPS-injected site observed by PET imaging was concordant with ex vivo ARG, upregulation of neuroinflammatory biomarkers, and elevated P2X7 expression levels. CONCLUSIONS While further work is needed to study [18F]JNJ-64413739 in other types of neuroinflammation, the current results favorably characterize [18F]JNJ-64413739 as a potential PET tracer of central neuroinflammation.
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Affiliation(s)
- Tamara Berdyyeva
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA.
| | - Chunfang Xia
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Natalie Taylor
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Yingbo He
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Gang Chen
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Chaofeng Huang
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Wei Zhang
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Hartmuth Kolb
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Michael Letavic
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA
| | - Anindya Bhattacharya
- Janssen Research & Development LLC, 3210 Merryfield Row, San Diego, CA, 92121, USA
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Abstract
PURPOSE OF REVIEW To give an update on recent imaging studies probing positron emission tomography (PET) as a tool for improving biomarker-guided diagnosis of neuropsychiatric disorders. RECENT FINDINGS Several studies confirmed the value of imaging of regional neuronal activity and imaging of dopaminergic, serotonergic, and other neuroreceptor function in the diagnostic process of neuropsychiatric disorders, particularly schizophrenia, depression/bipolar disorder, substance use disorders, obsessive compulsive disorders (OCD), and attention-deficit/hyperactivity disorder. Additionally, imaging brain microglial activation using translocator protein 18 kDa (TSPO) radiotracer allows for unique in-vivo insights into pathophysiological neuroinflammatory changes underlying schizophrenia, affective disorders, and OCD. SUMMARY The role of PET imaging in the biomarker-guided diagnostic process of neuropsychiatric disorders has been increasingly acknowledged in recent years. Future prospective studies are needed to define the value of PET imaging for diagnosis, treatment decisions, and prognosis in neuropsychiatric disorders.
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19
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Cavaliere C, Tramontano L, Fiorenza D, Alfano V, Aiello M, Salvatore M. Gliosis and Neurodegenerative Diseases: The Role of PET and MR Imaging. Front Cell Neurosci 2020; 14:75. [PMID: 32327973 PMCID: PMC7161920 DOI: 10.3389/fncel.2020.00075] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 03/13/2020] [Indexed: 12/16/2022] Open
Abstract
Glial activation characterizes most neurodegenerative and psychiatric diseases, often anticipating clinical manifestations and macroscopical brain alterations. Although imaging techniques have improved diagnostic accuracy in many neurological conditions, often supporting diagnosis, prognosis prediction and treatment outcome, very few molecular imaging probes, specifically focused on microglial and astrocytic activation, have been translated to a clinical setting. In this context, hybrid positron emission tomography (PET)/magnetic resonance (MR) scanners represent the most advanced tool for molecular imaging, combining the functional specificity of PET radiotracers (e.g., targeting metabolism, hypoxia, and inflammation) to both high-resolution and multiparametric information derived by MR in a single imaging acquisition session. This simultaneity of findings achievable by PET/MR, if useful for reciprocal technical adjustments regarding temporal and spatial cross-modal alignment/synchronization, opens still debated issues about its clinical value in neurological patients, possibly incompliant and highly variable from a clinical point of view. While several preclinical and clinical studies have investigated the sensitivity of PET tracers to track microglial (mainly TSPO ligands) and astrocytic (mainly MAOB ligands) activation, less studies have focused on MR specificity to this topic (e.g., through the assessment of diffusion properties and T2 relaxometry), and only few exploiting the integration of simultaneous hybrid acquisition. This review aims at summarizing and critically review the current state about PET and MR imaging for glial targets, as well as the potential added value of hybrid scanners for characterizing microglial and astrocytic activation.
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20
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De Picker L, Morrens M. Perspective: Solving the Heterogeneity Conundrum of TSPO PET Imaging in Psychosis. Front Psychiatry 2020; 11:362. [PMID: 32425835 PMCID: PMC7206714 DOI: 10.3389/fpsyt.2020.00362] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 04/09/2020] [Indexed: 12/11/2022] Open
Abstract
Positron emission tomography using ligands targeting translocator protein 18 kDa (TSPO PET) is an innovative method to visualize and quantify glial inflammatory responses in the central nervous system in vivo. Compared to some other neuropsychiatric disorders, findings of TSPO PET in schizophrenia and related psychotic disorders have been considerably more heterogeneous. Two conflicting meta-analyses have been published on the topic within the last year: one asserting evidence for decreased TSPO uptake, while the other observed increased TSPO uptake in a selection of studies. In this paper, we review and discuss five hypotheses which may explain the observed variability of TSPO PET findings in psychotic illness, namely that (1) an inflammatory phenotype is only present in a subgroup of psychosis patients; (2) heterogeneity is caused by interference of antipsychotic medication; (3) interference of other clinical confounders in the study populations (such as age, sex, BMI, smoking, and substance use); or (4) methodological variability between studies (such as choice of tracer and kinetic model, genotyping, study power, and diurnal effects); and (5) the glial responses underlying changes in TSPO expression are themselves heterogeneous and dynamic. Finally, we propose four key recommendations for future research proposals to mitigate these different causes of heterogeneity.
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Affiliation(s)
- Livia De Picker
- Collaborative Antwerp Psychiatric Research Institute, University of Antwerp, Antwerp, Belgium.,SINAPS, University Psychiatric Hospital Campus Duffel, Duffel, Belgium
| | - Manuel Morrens
- Collaborative Antwerp Psychiatric Research Institute, University of Antwerp, Antwerp, Belgium.,SINAPS, University Psychiatric Hospital Campus Duffel, Duffel, Belgium
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21
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Ellis JK, Walker EF, Goldsmith DR. Selective Review of Neuroimaging Findings in Youth at Clinical High Risk for Psychosis: On the Path to Biomarkers for Conversion. Front Psychiatry 2020; 11:567534. [PMID: 33173516 PMCID: PMC7538833 DOI: 10.3389/fpsyt.2020.567534] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 08/31/2020] [Indexed: 12/19/2022] Open
Abstract
First episode psychosis (FEP), and subsequent diagnosis of schizophrenia or schizoaffective disorder, predominantly occurs during late adolescence, is accompanied by a significant decline in function and represents a traumatic experience for patients and families alike. Prior to first episode psychosis, most patients experience a prodromal period of 1-2 years, during which symptoms first appear and then progress. During that time period, subjects are referred to as being at Clinical High Risk (CHR), as a prodromal period can only be designated in hindsight in those who convert. The clinical high-risk period represents a critical window during which interventions may be targeted to slow or prevent conversion to psychosis. However, only one third of subjects at clinical high risk will convert to psychosis and receive a formal diagnosis of a primary psychotic disorder. Therefore, in order for targeted interventions to be developed and applied, predicting who among this population will convert is of critical importance. To date, a variety of neuroimaging modalities have identified numerous differences between CHR subjects and healthy controls. However, complicating attempts at predicting conversion are increasingly recognized co-morbidities, such as major depressive disorder, in a significant number of CHR subjects. The result of this is that phenotypes discovered between CHR subjects and healthy controls are likely non-specific to psychosis and generalized for major mental illness. In this paper, we selectively review evidence for neuroimaging phenotypes in CHR subjects who later converted to psychosis. We then evaluate the recent landscape of machine learning as it relates to neuroimaging phenotypes in predicting conversion to psychosis.
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Affiliation(s)
- Justin K Ellis
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, United States
| | - Elaine F Walker
- Department of Psychology, Emory University, Atlanta, GA, United States
| | - David R Goldsmith
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, United States
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22
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Schifani C, Hafizi S, Tseng HH, Gerritsen C, Kenk M, Wilson AA, Houle S, Rusjan PM, Mizrahi R. Preliminary data indicating a connection between stress-induced prefrontal dopamine release and hippocampal TSPO expression in the psychosis spectrum. Schizophr Res 2019; 213:80-86. [PMID: 30409695 PMCID: PMC6500775 DOI: 10.1016/j.schres.2018.10.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 10/12/2018] [Accepted: 10/16/2018] [Indexed: 12/31/2022]
Abstract
Prolonged stress can cause neuronal loss in the hippocampus resulting in disinhibition of glutamatergic neurons proposed to enhance dopaminergic firing in subcortical regions including striatal areas. Supporting this, imaging studies show increased striatal dopamine release in response to psychosocial stress in healthy individuals with low childhood maternal care, individuals at clinical high risk for psychosis (CHR) and patients with schizophrenia. The prefrontal cortex (PFC) is connected to the hippocampus and a key region to control neurochemical responses to stressful stimuli. We recently reported a disrupted PFC dopamine-stress regulation in schizophrenia, which was intact in CHR. Given the available evidence on the link between psychosocial stress, PFC dopamine release and hippocampal immune activation in psychosis, we explored, for the first time in vivo, whether stress-induced PFC dopamine release is associated with hippocampal TSPO expression (a neuroimmune marker) in the psychosis spectrum. We used an overlapping sample of antipsychotic-naïve subjects with CHR (n = 6) and antipsychotic-free schizophrenia patients (n = 9) from our previously published studies, measuring PFC dopamine release induced by a psychosocial stress task with [11C]FLB457 positron emission tomography (PET) and TSPO expression with [18F]FEPPA PET. We observed that participants on the psychosis spectrum with lower stress-induced dopamine release in PFC had significantly higher TSPO expression in hippocampus (β = -2.39, SE = 0.96, F(1,11) = 6.17, p = 0.030). Additionally, we report a positive association between stress-induced PFC dopamine release, controlled for hippocampal TSPO expression, and Global Assessment of Functioning. This is the first exploration of the relationship between PFC dopamine release and hippocampal TSPO expression in vivo in humans.
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Affiliation(s)
- Christin Schifani
- Research Imaging Centre, Centre for Addiction and Mental
Health, Toronto, Ontario, Canada
| | - Sina Hafizi
- Research Imaging Centre, Centre for Addiction and Mental
Health, Toronto, Ontario, Canada
| | - Huai-Hsuan Tseng
- Research Imaging Centre, Centre for Addiction and Mental
Health, Toronto, Ontario, Canada
| | - Cory Gerritsen
- Research Imaging Centre, Centre for Addiction and Mental
Health, Toronto, Ontario, Canada
| | - Miran Kenk
- Research Imaging Centre, Centre for Addiction and Mental
Health, Toronto, Ontario, Canada
| | - Alan A. Wilson
- Research Imaging Centre, Centre for Addiction and Mental
Health, Toronto, Ontario, Canada
| | - Sylvain Houle
- Research Imaging Centre, Centre for Addiction and Mental
Health, Toronto, Ontario, Canada
| | - Pablo M. Rusjan
- Research Imaging Centre, Centre for Addiction and Mental
Health, Toronto, Ontario, Canada,institute of Medical Science, University of Toronto,
Toronto, Ontario, Canada
| | - Romina Mizrahi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
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23
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Marques TR, Ashok AH, Pillinger T, Veronese M, Turkheimer FE, Dazzan P, Sommer IE, Howes OD. Neuroinflammation in schizophrenia: meta-analysis of in vivo microglial imaging studies. Psychol Med 2019; 49:2186-2196. [PMID: 30355368 PMCID: PMC6366560 DOI: 10.1017/s0033291718003057] [Citation(s) in RCA: 134] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 09/24/2018] [Accepted: 09/25/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND Converging lines of evidence implicate an important role for the immune system in schizophrenia. Microglia are the resident immune cells of the central nervous system and have many functions including neuroinflammation, axonal guidance and neurotrophic support. We aimed to provide a quantitative review of in vivo PET imaging studies of microglia activation in patients with schizophrenia compared with healthy controls. METHODS Demographic, clinical and imaging measures were extracted from each study and meta-analysis was conducted using a random-effects model (Hedge's g). The difference in 18-kDa translocator protein (TSPO) binding between patients with schizophrenia and healthy controls, as quantified by either binding potential (BP) or volume of distribution (VT), was used as the main outcome. Sub-analysis and sensitivity analysis were carried out to investigate the effects of genotype, ligand and illness stage. RESULTS In total, 12 studies comprising 190 patients with schizophrenia and 200 healthy controls met inclusion criteria. There was a significant elevation in tracer binding in schizophrenia patients relative to controls when BP was used as an outcome measure, (Hedge's g = 0.31; p = 0.03) but no significant differences when VT was used (Hedge's g = -0.22; p = 0.29). CONCLUSIONS In conclusion, there is evidence for moderate elevations in TSPO tracer binding in grey matter relative to other brain tissue in schizophrenia when using BP as an outcome measure, but no difference when VT is the outcome measure. We discuss the relevance of these findings as well as the methodological issues that may underlie the contrasting difference between these outcomes.
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Affiliation(s)
- Tiago Reis Marques
- Psychiatric Imaging Group, MRC Clinical Sciences Centre, Du Cane Road, London W12 0NN, UK
- Psychiatric Imaging Group, London Institute of Medical Sciences (LMS), Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
| | - Abhishekh H Ashok
- Psychiatric Imaging Group, MRC Clinical Sciences Centre, Du Cane Road, London W12 0NN, UK
- Psychiatric Imaging Group, London Institute of Medical Sciences (LMS), Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, Kings College London, London, UK
| | - Toby Pillinger
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, Kings College London, London, UK
| | - Mattia Veronese
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, Kings College London, London, UK
| | - Federico E. Turkheimer
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, Kings College London, London, UK
| | - Paola Dazzan
- Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, Kings College London, London, UK
| | - Iris E.C. Sommer
- Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Oliver D Howes
- Psychiatric Imaging Group, MRC Clinical Sciences Centre, Du Cane Road, London W12 0NN, UK
- Psychiatric Imaging Group, London Institute of Medical Sciences (LMS), Faculty of Medicine, Imperial College London, Du Cane Road, London W12 0NN, UK
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, Kings College London, London, UK
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24
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Hashimoto K. Recent Advances in the Early Intervention in Schizophrenia: Future Direction from Preclinical Findings. Curr Psychiatry Rep 2019; 21:75. [PMID: 31278495 DOI: 10.1007/s11920-019-1063-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE OF REVIEW In the past decade, there has been increasing interest in the potential benefit of early intervention in schizophrenia. Patients with schizophrenia show cognitive impairment for several years preceding the onset of psychosis. The author discusses the recent topics on prevention of schizophrenia. RECENT FINDINGS Preclinical findings suggest that maternal immune activation (MIA) produces cognitive deficits as a prodromal symptom in juvenile offspring in rodents. Treatment with anti-inflammatory compounds, such as D-serine, 7,8-dihydroxyflavone (a TrkB agonist), sulforaphane (or its precursor glucoraphanin), and TPPU (1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea: a soluble epoxide hydrolase inhibitor), during adolescence might prevent the onset of behavioral abnormalities and parvalbumin immunoreactivity in the medial prefrontal cortex of adult offspring after MIA. Based on the role of inflammation and cognitive impairment in the prodromal state, early intervention using anti-inflammatory compounds (i.e., D-serine, sodium benzoate, TrkB agonist, Nrf2 agonist, soluble epoxide hydrolase inhibitor) may reduce the risk of subsequent transition to schizophrenia.
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Affiliation(s)
- Kenji Hashimoto
- Division of Clinical Neuroscience, Chiba University Center for Forensic Mental Health, 1-8-1 Inohana, Chiba, 260-8670, Japan.
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25
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Da Silva T, Hafizi S, Rusjan PM, Houle S, Wilson AA, Prce I, Sailasuta N, Mizrahi R. GABA levels and TSPO expression in people at clinical high risk for psychosis and healthy volunteers: a PET-MRS study. J Psychiatry Neurosci 2019; 44:111-119. [PMID: 30255837 PMCID: PMC6397035 DOI: 10.1503/jpn.170201] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND γ-Aminobutyric acidergic (GABAergic) dysfunction and immune activation have been implicated in the pathophysiology of schizophrenia. Preclinical evidence suggests that inflammation-related abnormalities may contribute to GABAergic alterations in the brain, but this has never been investigated in vivo in humans. In this multimodal imaging study, we quantified cerebral GABA plus macromolecule (GABA+) levels in antipsychotic-naive people at clinical high risk for psychosis and in healthy volunteers. We investigated for the first time the association between GABA+ levels and expression of translocator protein 18 kDa (TSPO; a marker of microglial activation) using positron emission tomography (PET). METHODS Thirty-five people at clinical high risk for psychosis and 18 healthy volunteers underwent 3 T proton magnetic resonance spectroscopy to obtain GABA+ levels in the medial prefrontal cortex (mPFC). A subset (29 people at clinical high risk for psychosis and 15 healthy volunteers) also underwent a high-resolution [18F]FEPPA PET scan to quantify TSPO expression. Each participant was genotyped for the TSPO rs6971 polymorphism. RESULTS We found that GABA+ levels were significantly associated with TSPO expression in the mPFC (F1,40 = 10.45, p = 0.002). We found no significant differences in GABA+ levels in the mPFC (F1,51 = 0.00, p > 0.99) between people at clinical high risk for psychosis and healthy volunteers. We found no significant correlations between GABA+ levels or residuals of the association with TSPO expression and the severity of prodromal symptoms or cognition. LIMITATIONS Given the cross-sectional nature of this study, we could determine no cause-and-effect relationships for GABA alterations and TSPO expression. CONCLUSION Our findings suggest that TSPO expression is negatively associated with GABA+ levels in the prefrontal cortex, independent of disease status.
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Affiliation(s)
- Tania Da Silva
- From the Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Silva, Hafizi, Rusjan, Houle, Wilson, Prce, Sailasuta, Mizrahi); the Institute of Medical Science, University of Toronto, Toronto, Ont., Canada (Silva, Rusjan, Mizrahi); the Department of Psychiatry, University of Toronto, Toronto, Ont., Canada (Rusjan, Houle, Wilson, Mizrahi); and the Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Rusjan, Houle, Sailasuta, Mizrahi)
| | - Sina Hafizi
- From the Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Silva, Hafizi, Rusjan, Houle, Wilson, Prce, Sailasuta, Mizrahi); the Institute of Medical Science, University of Toronto, Toronto, Ont., Canada (Silva, Rusjan, Mizrahi); the Department of Psychiatry, University of Toronto, Toronto, Ont., Canada (Rusjan, Houle, Wilson, Mizrahi); and the Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Rusjan, Houle, Sailasuta, Mizrahi)
| | - Pablo M Rusjan
- From the Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Silva, Hafizi, Rusjan, Houle, Wilson, Prce, Sailasuta, Mizrahi); the Institute of Medical Science, University of Toronto, Toronto, Ont., Canada (Silva, Rusjan, Mizrahi); the Department of Psychiatry, University of Toronto, Toronto, Ont., Canada (Rusjan, Houle, Wilson, Mizrahi); and the Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Rusjan, Houle, Sailasuta, Mizrahi)
| | - Sylvain Houle
- From the Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Silva, Hafizi, Rusjan, Houle, Wilson, Prce, Sailasuta, Mizrahi); the Institute of Medical Science, University of Toronto, Toronto, Ont., Canada (Silva, Rusjan, Mizrahi); the Department of Psychiatry, University of Toronto, Toronto, Ont., Canada (Rusjan, Houle, Wilson, Mizrahi); and the Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Rusjan, Houle, Sailasuta, Mizrahi)
| | - Alan A Wilson
- From the Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Silva, Hafizi, Rusjan, Houle, Wilson, Prce, Sailasuta, Mizrahi); the Institute of Medical Science, University of Toronto, Toronto, Ont., Canada (Silva, Rusjan, Mizrahi); the Department of Psychiatry, University of Toronto, Toronto, Ont., Canada (Rusjan, Houle, Wilson, Mizrahi); and the Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Rusjan, Houle, Sailasuta, Mizrahi)
| | - Ivana Prce
- From the Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Silva, Hafizi, Rusjan, Houle, Wilson, Prce, Sailasuta, Mizrahi); the Institute of Medical Science, University of Toronto, Toronto, Ont., Canada (Silva, Rusjan, Mizrahi); the Department of Psychiatry, University of Toronto, Toronto, Ont., Canada (Rusjan, Houle, Wilson, Mizrahi); and the Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Rusjan, Houle, Sailasuta, Mizrahi)
| | - Napapon Sailasuta
- From the Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Silva, Hafizi, Rusjan, Houle, Wilson, Prce, Sailasuta, Mizrahi); the Institute of Medical Science, University of Toronto, Toronto, Ont., Canada (Silva, Rusjan, Mizrahi); the Department of Psychiatry, University of Toronto, Toronto, Ont., Canada (Rusjan, Houle, Wilson, Mizrahi); and the Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Rusjan, Houle, Sailasuta, Mizrahi)
| | - Romina Mizrahi
- From the Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Silva, Hafizi, Rusjan, Houle, Wilson, Prce, Sailasuta, Mizrahi); the Institute of Medical Science, University of Toronto, Toronto, Ont., Canada (Silva, Rusjan, Mizrahi); the Department of Psychiatry, University of Toronto, Toronto, Ont., Canada (Rusjan, Houle, Wilson, Mizrahi); and the Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ont., Canada (Rusjan, Houle, Sailasuta, Mizrahi)
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26
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López-González I, Pinacho R, Vila È, Escanilla A, Ferrer I, Ramos B. Neuroinflammation in the dorsolateral prefrontal cortex in elderly chronic schizophrenia. Eur Neuropsychopharmacol 2019; 29:384-396. [PMID: 30630651 DOI: 10.1016/j.euroneuro.2018.12.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 11/07/2018] [Accepted: 12/16/2018] [Indexed: 01/11/2023]
Abstract
Cognitive deterioration and symptom progression occur in schizophrenia over the course of the disorder. A dysfunction of the immune system/neuroinflammatory pathways has been linked to schizophrenia (SZ). These altered processes in the dorsolateral prefrontal cortex (DLPFC) could contribute to the worsening of the deficits. However, limited studies are available in this brain region in elderly population with long-term treatments. In this study, we explore the possible deregulation of 21 key genes involved in immune homeostasis, including pro- and anti-inflammatory cytokines, cytokine modulators (toll-like receptors, colony-stimulating factors, and members of the complement system) and microglial and astroglial markers in the DLPFC in elderly chronic schizophrenia. We used quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR) on extracts from postmortem DLPFC of elderly subjects with chronic SZ (n = 14) compared to healthy control individuals (n = 14). We report that CSF1R, TLR4, IL6, TNFα, TNFRSF1A, IL10, IL10RA, IL10RB, and CD68 were down-regulated in elderly SZ subjects. Moreover, we found that the expression levels of all the altered inflammatory genes in SZ correlated with the microglial marker CD68. However, no associations were found with the astroglial marker GFAP. This study reveals a decrease in the gene expression of cytokines and immune response/inflammation mediators in the DLPFC of elderly subjects with chronic schizophrenia, supporting the idea of a dysfunction of these processes in aged patients and its possible relationship with active microglia abundance. These findings include elements that might contribute to the cognitive decline and symptom progression linked to DLPFC functioning at advanced stages of the disease.
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Affiliation(s)
- Irene López-González
- Neuropathology, Bellvitge University Hospital, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Raquel Pinacho
- Psiquiatria Molecular, Institut de Recerca Sant Joan de Déu, Santa Rosa 39-57, 08950 Esplugues de Llobregat, Spain
| | - Èlia Vila
- Psiquiatria Molecular, Institut de Recerca Sant Joan de Déu, Santa Rosa 39-57, 08950 Esplugues de Llobregat, Spain; Parc Sanitari Sant Joan de Déu, Dr. Antoni Pujadas, 42, 08830 Sant Boi de Llobregat, Spain
| | - Ana Escanilla
- Parc Sanitari Sant Joan de Déu, Dr. Antoni Pujadas, 42, 08830 Sant Boi de Llobregat, Spain; Banc de Teixits Neurologics, Parc Sanitari Sant Joan de Déu, 08830 Sant Boi de Llobregat, Spain
| | - Isidre Ferrer
- Neuropathology, Bellvitge University Hospital, IDIBELL, L'Hospitalet de Llobregat, Barcelona, Spain; Departament de Patologia i Terapeutica Experimental, University of Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain; CIBERNED (Biomedical Network Research Center of Neurodegenerative Diseases), Ministry of Economy, Industry and Competitiveness Institute of Health Carlos III, Madrid, Spain.
| | - Belén Ramos
- Psiquiatria Molecular, Institut de Recerca Sant Joan de Déu, Santa Rosa 39-57, 08950 Esplugues de Llobregat, Spain; Parc Sanitari Sant Joan de Déu, Dr. Antoni Pujadas, 42, 08830 Sant Boi de Llobregat, Spain; Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAM (Biomedical Network Research Center of Mental Health), Ministry of Economy, Industry and Competitiveness Institute of Health Carlos III, Madrid, Spain; Dept. de Bioquímica i Biologia Molecular, Facultat de Medicina, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain.
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27
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Hafizi S, Guma E, Koppel A, Da Silva T, Kiang M, Houle S, Wilson AA, Rusjan PM, Chakravarty MM, Mizrahi R. TSPO expression and brain structure in the psychosis spectrum. Brain Behav Immun 2018; 74:79-85. [PMID: 29906515 PMCID: PMC6289857 DOI: 10.1016/j.bbi.2018.06.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 06/06/2018] [Accepted: 06/09/2018] [Indexed: 01/18/2023] Open
Abstract
Psychosis is associated with abnormal structural changes in the brain including decreased regional brain volumes and abnormal brain morphology. However, the underlying causes of these structural abnormalities are less understood. The immune system, including microglial activation, has been implicated in the pathophysiology of psychosis. Although previous studies have suggested a connection between peripheral proinflammatory cytokines and structural brain abnormalities in schizophrenia, no in-vivo studies have investigated whether microglial activation is also linked to brain structure alterations previously observed in schizophrenia and its putative prodrome. In this study, we investigated the link between mitochondrial 18 kDa translocator protein (TSPO) and structural brain characteristics (i.e. regional brain volume, cortical thickness, and hippocampal shape) in key brain regions such as dorsolateral prefrontal cortex and hippocampus of a large group of participants (N = 90) including individuals at clinical high risk (CHR) for psychosis, first-episode psychosis (mostly antipsychotic-naïve) patients, and healthy volunteers. The participants underwent structural brain MRI scan and [18F]FEPPA positron emission tomography (PET) targeting TSPO. A significant [18F]FEPPA binding-by-group interaction was observed in morphological measures across the left hippocampus. In first-episode psychosis, we observed associations between [18F]FEPPA VT (total volume of distribution) and outward and inward morphological alterations, respectively, in the dorsal and ventro-medial portions of the left hippocampus. These associations were not significant in CHR or healthy volunteers. There was no association between [18F]FEPPA VT and other structural brain characteristics. Our findings suggest a link between TSPO expression and alterations in hippocampal morphology in first-episode psychosis.
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Affiliation(s)
- Sina Hafizi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Elisa Guma
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada
| | - Alex Koppel
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Tania Da Silva
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Michael Kiang
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada,Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - Sylvain Houle
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada,Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Alan A. Wilson
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Pablo M. Rusjan
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada,Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada,Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada,Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | - M. Mallar Chakravarty
- Douglas Mental Health University Institute, McGill University, Montreal, QC, Canada,Departments of Psychiatry and Biological and Biomedical Engineering, McGill University, Montreal, QC, Canada
| | - Romina Mizrahi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
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28
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Shakory S, Watts JJ, Hafizi S, Da Silva T, Khan S, Kiang M, Bagby RM, Chavez S, Mizrahi R. Hippocampal glutamate metabolites and glial activation in clinical high risk and first episode psychosis. Neuropsychopharmacology 2018; 43:2249-2255. [PMID: 30087434 PMCID: PMC6135774 DOI: 10.1038/s41386-018-0163-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 07/17/2018] [Accepted: 07/19/2018] [Indexed: 02/06/2023]
Abstract
Alterations in glutamate neurotransmission have been implicated in the pathophysiology of schizophrenia, as well as in symptom severity and cognitive deficits. The hippocampus, in particular, is a site of key functional and structural abnormalities in schizophrenia. Yet few studies have investigated hippocampal glutamate in antipsychotic-naïve first episode psychosis patients or in individuals at clinical high risk (CHR) of developing psychosis. Using proton magnetic resonance spectroscopy (1H-MRS), we investigated glutamate metabolite levels in the left hippocampus of 25 CHR (19 antipsychotic-naïve), 16 patients with first-episode psychosis (13 antipsychotic-naïve) and 31 healthy volunteers. We also explored associations between hippocampal glutamate metabolites and glial activation, as indexed by [18F]FEPPA positron emission tomography (PET); symptom severity; and cognitive function. Groups differed significantly in glutamate plus glutamine (Glx) levels (F(2, 69) = 6.39, p = 0.003). Post-hoc analysis revealed that CHR had significantly lower Glx levels than both healthy volunteers (p = 0.003) and first-episode psychosis patients (p = 0.050). No associations were found between glutamate metabolites and glial activation. Our findings suggest that glutamate metabolites are altered in CHR.
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Affiliation(s)
- Shima Shakory
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Jeremy J Watts
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - Sina Hafizi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Tania Da Silva
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Saad Khan
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Michael Kiang
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - R Michael Bagby
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Sofia Chavez
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Romina Mizrahi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada.
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada.
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.
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29
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Plavén-Sigray P, Matheson GJ, Collste K, Ashok AH, Coughlin JM, Howes OD, Mizrahi R, Pomper MG, Rusjan P, Veronese M, Wang Y, Cervenka S. Positron Emission Tomography Studies of the Glial Cell Marker Translocator Protein in Patients With Psychosis: A Meta-analysis Using Individual Participant Data. Biol Psychiatry 2018; 84:433-442. [PMID: 29653835 PMCID: PMC7893597 DOI: 10.1016/j.biopsych.2018.02.1171] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 02/13/2018] [Accepted: 02/20/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Accumulating evidence suggests that the immune system may be an important target for new treatment approaches in schizophrenia. Positron emission tomography and radioligands binding to the translocator protein (TSPO), which is expressed in glial cells in the brain including immune cells, represents a potential method for patient stratification and treatment monitoring. This study examined whether patients with first-episode psychosis and schizophrenia had altered TSPO levels compared with healthy control subjects. METHODS PubMed was searched for studies comparing patients with psychosis with healthy control subjects using second-generation TSPO radioligands. The outcome measure was total distribution volume (VT), an index of TSPO levels, in frontal cortex, temporal cortex, and hippocampus. Bayes factors (BFs) were applied to examine the relative support for higher, lower, or no difference in patients' TSPO levels compared with healthy control subjects. RESULTS Five studies, with 75 participants with first-episode psychosis or schizophrenia and 77 healthy control subjects, were included. BFs showed strong support for lower VT in patients relative to no difference (all BFs > 32), or relative to higher VT (all BFs > 422), in all brain regions. From the posterior distributions, mean patient-control differences in standardized VT values were -0.48 for frontal cortex (95% credible interval [CredInt] = -0.88 to 0.09), -0.47 for temporal cortex (CredInt = -0.87 to -0.07), and -0.63 for hippocampus (CredInt = -1.00 to -0.25). CONCLUSIONS The lower levels of TSPO observed in patients may correspond to altered function or lower density of brain immune cells. Future studies should focus on investigating the underlying biological mechanisms and their relevance for treatment.
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Affiliation(s)
- Pontus Plavén-Sigray
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet and Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden.
| | - Granville J Matheson
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet and Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
| | - Karin Collste
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet and Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
| | - Abhishekh H Ashok
- Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, United Kingdom; Medical Research Council London Institute of Medical Sciences, Hammersmith Hospital, London, United Kingdom; Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Jennifer M Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Oliver D Howes
- Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, United Kingdom; Medical Research Council London Institute of Medical Sciences, Hammersmith Hospital, London, United Kingdom; Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Romina Mizrahi
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Martin G Pomper
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, Maryland; Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Pablo Rusjan
- Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Mattia Veronese
- Department of Neuroimaging, Institute of Psychiatry, Psychology, & Neuroscience, King's College London, London, United Kingdom
| | - Yuchuan Wang
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, Maryland
| | - Simon Cervenka
- Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet and Stockholm Health Care Services, Stockholm County Council, Stockholm, Sweden
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30
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Khoury R, Nasrallah HA. Inflammatory biomarkers in individuals at clinical high risk for psychosis (CHR-P): State or trait? Schizophr Res 2018; 199:31-38. [PMID: 29703661 DOI: 10.1016/j.schres.2018.04.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Revised: 04/04/2018] [Accepted: 04/10/2018] [Indexed: 12/18/2022]
Abstract
BACKGROUND Studies linking neuro-inflammation to psychotic episodes has been rapidly expanding. Assessments of changes in inflammatory biomarkers in prodromal patients who subsequently convert to psychosis may help in predicting those likely to transition to psychosis. METHODS We reviewed the literature for original studies that measured inflammatory biomarkers in individuals at clinical high risk for psychosis (CHR-P), and compared pro-inflammatory biomarker data between converters and non-converters to psychosis as well as in healthy controls. RESULTS Our search yielded 15 studies. Our findings suggest a possible role of plasma levels of Interleukins-1β, 7, 8, matrix metalloproteinase (MMP)-8, cortisol, albumin and salivary cortisol, measured at baseline, as predictors of psychotic transition. Both baseline C-reactive protein (CRP) and Interleukin-6 levels were not shown to discriminate between converters and non-converters to psychosis. The dearth of longitudinal biomarker measures, before and after treating the psychotic episodes, was a limitation for assessing inflammatory biomarkers as trait vs state marker properties of biomarkers. DISCUSSION Gaps of data in published studies prevent confirming whether inflammatory biomarkers are state or trait indicators of transition to psychosis in the CHR-P populations. Future investigations should be designed to longitudinally measure inflammatory biomarkers in order to navigate the extensive heterogeneity of the schizophrenia syndrome and its prodrome.
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Affiliation(s)
- Rita Khoury
- Department of Psychiatry and Behavioral Neuroscience, Saint Louis University School of Medicine, United States.
| | - Henry A Nasrallah
- Department of Psychiatry and Behavioral Neuroscience, Saint Louis University School of Medicine, United States
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Hafizi S, Da Silva T, Meyer JH, Kiang M, Houle S, Remington G, Prce I, Wilson AA, Rusjan PM, Sailasuta N, Mizrahi R. Interaction between TSPO-a neuroimmune marker-and redox status in clinical high risk for psychosis: a PET-MRS study. Neuropsychopharmacology 2018; 43:1700-1705. [PMID: 29748630 PMCID: PMC6006145 DOI: 10.1038/s41386-018-0061-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 03/14/2018] [Accepted: 03/19/2018] [Indexed: 12/25/2022]
Abstract
Altered neuroimmune response and oxidative stress have both been implicated in the pathophysiology of schizophrenia. While preclinical studies have proposed several pathways regarding potential interactions between oxidative stress and neuroimmune imbalance in the development of psychosis, the molecular mechanisms underlying this interaction are not yet understood. To date, no study has investigated this link in vivo in the human brain. We conducted the first in vivo study linking translocator protein 18 kDa (TSPO) expression and glutathione (a major brain antioxidant and a marker for redox status) in the medial prefrontal cortex (mPFC) of a relatively large sample of participants (N = 48) including 27 antipsychotic-naïve individuals at clinical high risk for psychosis and 21 matched healthy volunteers using high-resolution PET with TSPO radioligand, [18F]FEPPA, and 3T proton magnetic resonance spectroscopy (1H MRS). The omnibus model (including TSPO genotype as covariate) was significant (F(4, 43) = 10.01, p < 0.001), with a significant group interaction (t = -2.10, p = 0.04), suggesting a different relation between [18F]FEPPA VT and glutathione in each clinical group. In healthy volunteers, but not in individuals at clinical high risk for psychosis, we found a significant negative association between glutathione levels and [18F]FEPPA VT (r = -0.60, p = 0.006). We observed no significant group differences with respect to [18F]FEPPA VT or glutathione levels. These findings suggest an abnormal interaction between TSPO expression and redox status in the clinical high risk states for psychosis.
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Affiliation(s)
- Sina Hafizi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Tania Da Silva
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Jeffrey H Meyer
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Michael Kiang
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Sylvain Houle
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Gary Remington
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Ivana Prce
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Alan A Wilson
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Pablo M Rusjan
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada
| | - Napapon Sailasuta
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Romina Mizrahi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada.
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada.
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.
- Department of Psychiatry, University of Toronto, Toronto, ON, Canada.
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32
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Vignal N, Cisternino S, Rizzo-Padoin N, San C, Hontonnou F, Gelé T, Declèves X, Sarda-Mantel L, Hosten B. [ 18F]FEPPA a TSPO Radioligand: Optimized Radiosynthesis and Evaluation as a PET Radiotracer for Brain Inflammation in a Peripheral LPS-Injected Mouse Model. Molecules 2018; 23:molecules23061375. [PMID: 29875332 PMCID: PMC6099542 DOI: 10.3390/molecules23061375] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 05/25/2018] [Accepted: 06/04/2018] [Indexed: 01/17/2023] Open
Abstract
[18F]FEPPA is a specific ligand for the translocator protein of 18 kDa (TSPO) used as a positron emission tomography (PET) biomarker for glial activation and neuroinflammation. [18F]FEPPA radiosynthesis was optimized to assess in a mouse model the cerebral inflammation induced by an intraperitoneal injection of Salmonella enterica serovar Typhimurium lipopolysaccharides (LPS; 5 mg/kg) 24 h before PET imaging. [18F]FEPPA was synthesized by nucleophilic substitution (90 °C, 10 min) with tosylated precursor, followed by improved semi-preparative HPLC purification (retention time 14 min). [18F]FEPPA radiosynthesis were carried out in 55 min (from EOB). The non-decay corrected radiochemical yield were 34 ± 2% (n = 17), and the radiochemical purity greater than 99%, with a molar activity of 198 ± 125 GBq/µmol at the end of synthesis. Western blot analysis demonstrated a 2.2-fold increase in TSPO brain expression in the LPS treated mice compared to controls. This was consistent with the significant increase of [18F]FEPPA brain total volume of distribution (VT) estimated with pharmacokinetic modelling. In conclusion, [18F]FEPPA radiosynthesis was implemented with high yields. The new purification/formulation with only class 3 solvents is more suitable for in vivo studies.
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Affiliation(s)
- Nicolas Vignal
- Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Louis, Unité Claude Kellershohn, 75010 Paris, France.
- Inserm UMR-S 1144, Faculté de Pharmacie de Paris, Université Paris Descartes, 75006 Paris, France.
| | - Salvatore Cisternino
- Inserm UMR-S 1144, Faculté de Pharmacie de Paris, Université Paris Descartes, 75006 Paris, France.
- Assistance Publique-Hôpitaux de Paris, Hôpital Universitaire Necker-Enfants Malades, 75015 Paris, France.
| | - Nathalie Rizzo-Padoin
- Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Louis, Unité Claude Kellershohn, 75010 Paris, France.
- Inserm UMR-S 1144, Faculté de Pharmacie de Paris, Université Paris Descartes, 75006 Paris, France.
| | - Carine San
- Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Louis, Unité Claude Kellershohn, 75010 Paris, France.
| | - Fortune Hontonnou
- Institut Universitaire d'Hématologie, Université Paris Diderot, 75013 Paris, France.
| | - Thibaut Gelé
- Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Louis, Unité Claude Kellershohn, 75010 Paris, France.
| | - Xavier Declèves
- Inserm UMR-S 1144, Faculté de Pharmacie de Paris, Université Paris Descartes, 75006 Paris, France.
- Assistance Publique-Hôpitaux de Paris, Hôpital Cochin, 75014 Paris, France.
| | - Laure Sarda-Mantel
- Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Louis, Unité Claude Kellershohn, 75010 Paris, France.
- Assistance Publique-Hôpitaux de Paris, Hôpital Lariboisière, Médecine Nucléaire, 75010 Paris, France.
- Inserm UMR-S 942, Université Paris Diderot, 75013 Paris, France.
| | - Benoît Hosten
- Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Louis, Unité Claude Kellershohn, 75010 Paris, France.
- Inserm UMR-S 1144, Faculté de Pharmacie de Paris, Université Paris Descartes, 75006 Paris, France.
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33
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Girgis RR, Ciarleglio A, Choo T, Haynes G, Bathon JM, Cremers S, Kantrowitz JT, Lieberman JA, Brown AS. A Randomized, Double-Blind, Placebo-Controlled Clinical Trial of Tocilizumab, An Interleukin-6 Receptor Antibody, For Residual Symptoms in Schizophrenia. Neuropsychopharmacology 2018; 43:1317-1323. [PMID: 29090685 PMCID: PMC5916349 DOI: 10.1038/npp.2017.258] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 10/01/2017] [Accepted: 10/24/2017] [Indexed: 01/16/2023]
Abstract
Evidence from preclinical, epidemiological, and human studies indicates that inflammation, and in particular elevated interleukin-6 (IL-6) activity, may be related to clinical manifestations and pathophysiology of schizophrenia. Furthermore, studies in preclinical models suggest that decreasing IL-6 activity may mitigate or reverse some of these deficits. The purpose of this trial was to test whether an IL-6 receptor antibody, tocilizumab, would improve residual positive and negative symptoms and cognitive deficits in schizophrenia. We randomized 36 clinically stable, moderately symptomatic (i.e., Positive and Negative Syndrome Scale (PANSS) >60) individuals with schizophrenia to 3 monthly infusions of 8 mg/kg tocilizumab or placebo (normal saline). The primary outcome was effect at week 12 on the PANSS Total Score. Effects on the MATRICS, other PANSS subscales, Clinical Global Impression, and Global Assessment of Functioning were secondary outcomes. There were no observed treatment effects on any behavioral outcome measure. Baseline C-reactive protein (CRP) or cytokine levels did not predict treatment outcome, nor were there correlations between changes in these inflammatory markers and the measured outcomes. As expected, IL-6 and IL-8 increased, while CRP decreased, in the tocilizumab group compared with the placebo group. This study did not reveal any evidence that an IL-6 receptor antibody affects behavioral outcomes in schizophrenia. One potential explanation is the lack of capacity of this agent to penetrate the central nervous system. Additional trials of medications aimed at targeting cytokine overactivity that act directly on brain function and/or treatment in early-stage psychosis populations are needed.
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Affiliation(s)
- Ragy R Girgis
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA,New York State Psychiatric Institute, New York, NY, USA,Department of Psychiatry, Columbia University College of Physicians and Surgeons, 1051 Riverside Drive, Unit 31, New York 10032, NY, USA. Tel: +1 646 774 5553; Fax: +1 646 774 5237; E-mail:
| | - Adam Ciarleglio
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA,New York State Psychiatric Institute, New York, NY, USA
| | - Tse Choo
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA,New York State Psychiatric Institute, New York, NY, USA
| | - Gregory Haynes
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA,New York State Psychiatric Institute, New York, NY, USA
| | - Joan M Bathon
- Department of Medicine, Columbia University, New York, NY, USA
| | - Serge Cremers
- Department of Pathology, Columbia University, New York, NY, USA
| | - Joshua T Kantrowitz
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA,New York State Psychiatric Institute, New York, NY, USA,Schizophrenia Research Center, Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA
| | - Jeffrey A Lieberman
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA,New York State Psychiatric Institute, New York, NY, USA
| | - Alan S Brown
- Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, NY, USA,New York State Psychiatric Institute, New York, NY, USA
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Mitochondrial function in individuals at clinical high risk for psychosis. Sci Rep 2018; 8:6216. [PMID: 29670128 PMCID: PMC5906614 DOI: 10.1038/s41598-018-24355-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 03/26/2018] [Indexed: 12/19/2022] Open
Abstract
Alterations in mitochondrial function have been implicated in the etiology of schizophrenia. Most studies have investigated alterations in mitochondrial function in patients in which the disorder is already established; however, whether mitochondrial dysfunction predates the onset of psychosis remains unknown. We measured peripheral mitochondrial complex (I–V) function and lactate/pyruvate levels in 27 antipsychotic-naïve individuals at clinical high risk for psychosis (CHR) and 16 healthy controls. We also explored the association between mitochondrial function and brain microglial activation and glutathione levels using a translocator protein 18 kDa [18F]FEPPA PET scan and 1H-MRS scan, respectively. There were no significant differences in mitochondrial complex function and lactate/pyruvate levels between CHR and healthy controls. In the CHR group, mitochondrial complex III function (r = −0.51, p = 0.008) and lactate levels (r = 0.61, p = 0.004) were associated with prodromal negative symptoms. As previously reported, there were no significant differences in microglial activation and glutathione levels between groups, however, mitochondrial complex IV function was inversely related to microglial activation in the hippocampus in CHR (r = −0.42, p = 0.04), but not in healthy controls. In conclusion, alterations in mitochondrial function are not yet evident in CHR, but may relate to the severity of prodromal symptoms, particularly negative symptoms.
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35
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Schifani C, Hafizi S, Da Silva T, Watts JJ, Khan MS, Mizrahi R. Using molecular imaging to understand early schizophrenia-related psychosis neurochemistry: a review of human studies. Int Rev Psychiatry 2017; 29:555-566. [PMID: 29219634 PMCID: PMC8011813 DOI: 10.1080/09540261.2017.1396205] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Schizophrenia is a chronic psychiatric disorder generally preceded by a so-called prodromal phase, which is characterized by attenuated psychotic symptoms. Advances in clinical research have enabled prospective identification of those individuals who are at clinical high risk (CHR) for psychosis, with the power to predict psychosis onset within the near future. Changes in several brain neurochemical systems and molecular mechanisms are implicated in the pathophysiology of schizophrenia and the psychosis spectrum, including the dopaminergic, γ-aminobutyric acid (GABA)-ergic, glutamatergic, endocannabinoid, and immunologic (i.e. glial activation) system and other promising future directions such as synaptic density, which are possible to quantify in vivo using positron emission tomography (PET). This paper aims to review in vivo PET studies in the mentioned systems in the early course of psychosis (i.e. CHR and first-episode psychosis (FEP)). The results of reviewed studies are promising; however, the current understanding of the underlying pathology of psychosis is still limited. Importantly, promising efforts involve the development of novel PET radiotracers targeting systems with growing interest in schizophrenia, like the nociceptive system and synaptic density.
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Affiliation(s)
- Christin Schifani
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Sina Hafizi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Tania Da Silva
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Jeremy Joseph Watts
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - M. Saad Khan
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Romina Mizrahi
- Research Imaging Centre, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
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36
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O'Donnell P. Microglia Activation in Subjects at Risk for Psychosis: Fact or Fiction? Neuropsychopharmacology 2017; 42:2472-2473. [PMID: 28820181 PMCID: PMC5686491 DOI: 10.1038/npp.2017.179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/03/2017] [Accepted: 08/04/2017] [Indexed: 01/14/2023]
Affiliation(s)
- Patricio O'Donnell
- Translational Research and Early Clinical, Takeda Pharmaceuticals, Cambridge, MA, USA,Takeda Pharmaceuticals, 350 Massachusetts Avenue, Cambridge, MA 02139, USA, Tel: +1 617 761 6829, E-mail:
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Pulagam KR, Colás L, Padro D, Plaza-García S, Gómez-Vallejo V, Higuchi M, Llop J, Martín A. Evaluation of the novel TSPO radiotracer [ 18F] VUIIS1008 in a preclinical model of cerebral ischemia in rats. EJNMMI Res 2017; 7:93. [PMID: 29177913 PMCID: PMC5701906 DOI: 10.1186/s13550-017-0343-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 11/12/2017] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND In vivo positron-emission tomography (PET) imaging of transporter protein (TSPO) expression is an attractive and indispensable tool for the diagnosis and therapy evaluation of neuroinflammation after cerebral ischemia. Despite several radiotracers have shown an excellent capacity to image neuroinflammation, novel radiotracers such as [18F] VUIIS1008 have shown promising properties to visualize and quantify the in vivo expression of TSPO. METHODS Longitudinal in vivo magnetic resonance (MRI) and PET imaging studies with the novel TSPO radiotracer 2-(5,7-diethyl-2-(4-(2-[18F] fluoroethoxy) phenyl) pyrazolo [1,5-a] pyrimidin-3-yl)-N, N-diethylacetamide ([18F] VUIIS1008), and (N, N-diethyl-2-(2-[4-(2-fluoroethoxy)-phenyl]-5,7-dimethyl-pyrazolo [1,5-a] yrimidin-3-yl)-acetamide ([18F] DPA-714) were carried out before and at days 1, 3, 7, 14, 21, and 28 following the transient middle cerebral artery occlusion (MCAO) in rats. RESULTS MRI images showed the extension and evolution of the brain infarction after ischemic stroke in rats. PET imaging with [18F] VUIIS1008 and [18F] DPA714 showed a progressive increase in the ischemic brain hemisphere during the first week, peaking at day 7 and followed by a decline from days 14 to 28 after cerebral ischemia. [18F] DPA714 uptake showed a mild uptake increase compared to [18F] VUIIS1008 in TSPO-rich ischemic brain regions. In vivo [18F] VUIIS1008 binding displacement with VUIIS1008 was more efficient than DPA714. Finally, immunohistochemistry confirmed a high expression of TSPO in microglial cells at day 7 after the MCAO in rats. CONCLUSIONS Altogether, these results suggest that [18F] VUIIS1008 could become a valuable tool for the diagnosis and treatment evaluation of neuroinflammation following ischemic stroke.
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Affiliation(s)
- Krishna R Pulagam
- Radiochemistry and Nuclear Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Lorena Colás
- Experimental Molecular Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Daniel Padro
- Magnetic Resonance Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Sandra Plaza-García
- Magnetic Resonance Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Vanessa Gómez-Vallejo
- Radiochemistry and Nuclear Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Makoto Higuchi
- National Institutes for Quantum and Radiological Science and Technology, National Institute of Radiological Sciences, Chiba, Japan
| | - Jordi Llop
- Radiochemistry and Nuclear Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Abraham Martín
- Experimental Molecular Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain.
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De Picker LJ, Morrens M, Chance SA, Boche D. Microglia and Brain Plasticity in Acute Psychosis and Schizophrenia Illness Course: A Meta-Review. Front Psychiatry 2017; 8:238. [PMID: 29201010 PMCID: PMC5696326 DOI: 10.3389/fpsyt.2017.00238] [Citation(s) in RCA: 95] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 11/01/2017] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVE Schizophrenia poses a tremendous health, social, and economic burden upon patients and society, indicating current treatment options remain inadequate. Recent findings from several lines of evidence have pointed to the importance of immune system involvement in not only premorbid neurodevelopmental but also subsequent symptom generation and aging processes of brain change in schizophrenia. In this meta-review, we use the summarized evidence from recent quantitative systematic reviews (SRs) and meta-analyses of several subspecialties to critically evaluate the hypothesis that immune-related processes shape the symptomatic presentation and illness course of schizophrenia, both directly and indirectly through altered neuroplasticity. METHODS We performed a data search in PubMed for English language SRs and meta-analyses from 2010 to 2017. The methodological quality of the SRs was assessed with the AMSTAR instrument. In addition, we review in this paper 11 original publications on translocator protein (TSPO) positron emission tomography (PET) imaging in schizophrenia. RESULTS We reviewed 26 SRs and meta-analyses. Evidence from clinical observational studies of inflammatory or immunological markers and randomized controlled drug trials of immunomodulatory compounds as add-on in the treatment of schizophrenia suggests psychotic exacerbations are accompanied by immunological changes different from those seen in non-acute states, and that the symptoms of schizophrenia can be modified by compounds such as non-steroidal anti-inflammatory drug and minocycline. Information derived from post-mortem brain tissue analysis and PET neuroimaging studies to evaluate microglial activation have added new perspectives to the available evidence, yet these results are very heterogeneous. Each research domain comes with unique opportunities as well as inherent limitations. A better understanding of the (patho-)physiology of microglial cells and their role in neuroplasticity is key to interpreting the immune-related findings in the context of schizophrenia illness exacerbations and progression. CONCLUSION Evidence from clinical studies analyzing patients' blood and cerebrospinal fluid samples, neuroimaging and post-mortem brain tissue suggests that aberrant immune responses may define schizophrenia illness' course through altered neuroplasticity representing abnormal aging processes. Most findings are however prone to bias and confounding, and often non-specific to schizophrenia, and a multidisciplinary translational approach is needed to consolidate these findings and link them to other schizophrenia hypotheses.
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Affiliation(s)
- Livia J De Picker
- Collaborative Antwerp Psychiatric Research Institute, University of Antwerp, Antwerp, Belgium.,University Psychiatric Center St. Norbertus, Duffel, Belgium
| | - Manuel Morrens
- Collaborative Antwerp Psychiatric Research Institute, University of Antwerp, Antwerp, Belgium.,University Psychiatric Center St. Norbertus, Duffel, Belgium
| | - Steven A Chance
- Nuffield Department of Clinical Neurosciences, West Wing, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Delphine Boche
- Clinical Neurosciences, Clinical and Experimental Sciences Academic Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
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