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Severance EG, Prandovszky E, Yang S, Leister F, Lea A, Wu CL, Tamouza R, Leboyer M, Dickerson F, Yolken RH. Prospects and Pitfalls of Plasma Complement C4 in Schizophrenia: Building a Better Biomarker. Dev Neurosci 2023; 45:349-360. [PMID: 37734326 DOI: 10.1159/000534185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 09/15/2023] [Indexed: 09/23/2023] Open
Abstract
Complex brain disorders like schizophrenia may have multifactorial origins related to mis-timed heritable and environmental factors interacting during neurodevelopment. Infections, inflammation, and autoimmune diseases are over-represented in schizophrenia leading to immune system-centered hypotheses. Complement component C4 is genetically and neurobiologically associated with schizophrenia, and its dual activity peripherally and in the brain makes it an exceptional target for biomarker development. Studies to evaluate the biomarker potential of plasma or serum C4 in schizophrenia do so to understand how peripheral C4 might reflect central nervous system-derived neuroinflammation, synapse pruning, and other mechanisms. This effort, however, has produced mostly conflicting results, with peripheral C4 sometimes elevated, reduced, or unchanged between comparison groups. We undertook a pilot biomarker development study to systematically identify sociodemographic, genetic, and immune-related variables (autoimmune, infection-related, gastrointestinal, inflammatory), which may be associated with plasma C4 levels in schizophrenia (SCH; n = 335) and/or in nonpsychiatric comparison subjects (NCs; n = 233). As with previously inconclusive studies, we detected no differences in plasma C4 levels between SCH and NCs. In contrast, levels of general inflammation, C-reactive protein (CRP), were significantly elevated in SCH compared to NCs (ANOVA, F = 20.74, p < 0.0001), suggestive that plasma C4 and CRP may reflect different sources or causes of inflammation. In multivariate regressions of C4 gene copy number variants, plasma C4 levels were correlated only for C4A (not C4B, C4L, C4S) and only in NCs (R Coeff = 0.39, CI = 0.01-0.77, R2 = 0.18, p < 0.01; not SCH). Other variables associated with plasma C4 levels only in NCs included sex, double-stranded DNA IgG, tissue-transglutaminase (TTG) IgG, and cytomegalovirus IgG. Toxoplasma gondii IgG was the only variable significantly correlated with plasma C4 in SCH but not in NCs. Many variables were associated with plasma C4 in both groups (body mass index, race, CRP, N-methyl-D-aspartate receptor (NMDAR) NR2 subunit IgG, TTG IgA, lipopolysaccharide-binding protein (LBP), and soluble CD14 (sCD14). While the direction of most C4 associations was positive, autoimmune markers tended to be inverse, and associated with reduced plasma C4 levels. When NMDAR-NR2 autoantibody-positive individuals were removed, plasma C4 was elevated in SCH versus NCs (ANOVA, F = 5.16, p < 0.02). Our study was exploratory and confirmation of the many variables associated with peripheral C4 requires replication. Our preliminary results point toward autoimmune factors and exposure to the pathogen, T. gondii, as possibly significant contributors to variability of total C4 protein levels in plasma of individuals with schizophrenia.
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Affiliation(s)
- Emily G Severance
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Emese Prandovszky
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Shuojia Yang
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Flora Leister
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Ashley Lea
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Ching-Lien Wu
- Université Paris-Est Créteil (UPEC), INSERM, IMRB, Translational Neuropsychiatry, AP-HP, Hôpital Universitaire Henri Mondor, Fédération Hospitalo-Universitaire de Médecine de Précision en Psychiatrie, Fondation FondaMental, Créteil, France
| | - Ryad Tamouza
- Université Paris-Est Créteil (UPEC), INSERM, IMRB, Translational Neuropsychiatry, AP-HP, Hôpital Universitaire Henri Mondor, Fédération Hospitalo-Universitaire de Médecine de Précision en Psychiatrie, Fondation FondaMental, Créteil, France
| | - Marion Leboyer
- Université Paris-Est Créteil (UPEC), INSERM, IMRB, Translational Neuropsychiatry, AP-HP, Hôpital Universitaire Henri Mondor, Fédération Hospitalo-Universitaire de Médecine de Précision en Psychiatrie, Fondation FondaMental, Créteil, France
| | - Faith Dickerson
- Stanley Research Program, Sheppard Pratt, Baltimore, Maryland, USA
| | - Robert H Yolken
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Howes OD, Onwordi EC. The synaptic hypothesis of schizophrenia version III: a master mechanism. Mol Psychiatry 2023; 28:1843-1856. [PMID: 37041418 PMCID: PMC10575788 DOI: 10.1038/s41380-023-02043-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 03/16/2023] [Accepted: 03/20/2023] [Indexed: 04/13/2023]
Abstract
The synaptic hypothesis of schizophrenia has been highly influential. However, new approaches mean there has been a step-change in the evidence available, and some tenets of earlier versions are not supported by recent findings. Here, we review normal synaptic development and evidence from structural and functional imaging and post-mortem studies that this is abnormal in people at risk and with schizophrenia. We then consider the mechanism that could underlie synaptic changes and update the hypothesis. Genome-wide association studies have identified a number of schizophrenia risk variants converging on pathways regulating synaptic elimination, formation and plasticity, including complement factors and microglial-mediated synaptic pruning. Induced pluripotent stem cell studies have demonstrated that patient-derived neurons show pre- and post-synaptic deficits, synaptic signalling alterations, and elevated, complement-dependent elimination of synaptic structures compared to control-derived lines. Preclinical data show that environmental risk factors linked to schizophrenia, such as stress and immune activation, can lead to synapse loss. Longitudinal MRI studies in patients, including in the prodrome, show divergent trajectories in grey matter volume and cortical thickness compared to controls, and PET imaging shows in vivo evidence for lower synaptic density in patients with schizophrenia. Based on this evidence, we propose version III of the synaptic hypothesis. This is a multi-hit model, whereby genetic and/or environmental risk factors render synapses vulnerable to excessive glia-mediated elimination triggered by stress during later neurodevelopment. We propose the loss of synapses disrupts pyramidal neuron function in the cortex to contribute to negative and cognitive symptoms and disinhibits projections to mesostriatal regions to contribute to dopamine overactivity and psychosis. It accounts for the typical onset of schizophrenia in adolescence/early adulthood, its major risk factors, and symptoms, and identifies potential synaptic, microglial and immune targets for treatment.
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Affiliation(s)
- Oliver D Howes
- Faculty of Medicine, Institute of Clinical Sciences (ICS), Imperial College London, London, W12 0NN, UK.
- Psychiatric Imaging Group, Medical Research Council, London Institute of Medical Sciences, Hammersmith Hospital, London, W12 0NN, UK.
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE5 8AF, UK.
| | - Ellis Chika Onwordi
- Faculty of Medicine, Institute of Clinical Sciences (ICS), Imperial College London, London, W12 0NN, UK.
- Psychiatric Imaging Group, Medical Research Council, London Institute of Medical Sciences, Hammersmith Hospital, London, W12 0NN, UK.
- Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, SE5 8AF, UK.
- Centre for Psychiatry and Mental Health, Wolfson Institute of Population Health, Queen Mary University of London, London, E1 2AB, UK.
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3
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Sun P, Wu Z, Lin L, Hu G, Zhang X, Wang J. MR-Nucleomics: The study of pathological cellular processes with multinuclear magnetic resonance spectroscopy and imaging in vivo. NMR IN BIOMEDICINE 2023; 36:e4845. [PMID: 36259659 DOI: 10.1002/nbm.4845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 09/28/2022] [Accepted: 10/08/2022] [Indexed: 06/16/2023]
Abstract
Clinical medicine has experienced a rapid development in recent decades, during which therapies targeting specific cellular signaling pathways, or specific cell surface receptors, have been increasingly adopted. While these developments in clinical medicine call for improved precision in diagnosis and treatment monitoring, modern medical imaging methods are restricted mainly to anatomical imaging, lagging behind the requirements of precision medicine. Although positron emission tomography and single photon emission computed tomography have been used clinically for studies of metabolism, their applications have been limited by the exposure risk to ionizing radiation, the subsequent limitation in repeated and longitudinal studies, and the incapability in assessing downstream metabolism. Magnetic resonance spectroscopy (MRS) or spectroscopic imaging (MRSI) are, in theory, capable of assessing molecular activities in vivo, although they are often limited by sensitivity. Here, we review some recent developments in MRS and MRSI of multiple nuclei that have potential as molecular imaging tools in the clinic.
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Affiliation(s)
- Peng Sun
- Clinical & Technical Support, Philips Healthcare, China
| | - Zhigang Wu
- Clinical & Technical Support, Philips Healthcare, China
| | - Liangjie Lin
- Clinical & Technical Support, Philips Healthcare, China
| | - Geli Hu
- Clinical & Technical Support, Philips Healthcare, China
| | | | - Jiazheng Wang
- Clinical & Technical Support, Philips Healthcare, China
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McGuigan BN, Santini T, Keshavan MS, Prasad KM. Gene Expressions Preferentially Influence Cortical Thickness of Human Connectome Project Atlas Parcellated Regions in First-Episode Antipsychotic-Naïve Psychoses. SCHIZOPHRENIA BULLETIN OPEN 2023; 4:sgad019. [PMID: 37621304 PMCID: PMC10445951 DOI: 10.1093/schizbullopen/sgad019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Altered gene expressions may mechanistically link genetic factors with brain morphometric alterations. Existing gene expression studies have examined selected morphometric features using low-resolution atlases in medicated schizophrenia. We examined the relationship of gene expression with cortical thickness (CT), surface area (SA), and gray matter volume (GMV) of first-episode antipsychotic-naïve psychosis patients (FEAP = 85) and 81 controls, hypothesizing that gene expressions often associated with psychosis will differentially associate with different morphometric features. We explored such associations among schizophrenia and non-schizophrenia subgroups within FEAP group compared to controls. We mapped 360 Human Connectome Project atlas-based parcellations on brain MRI on to the publicly available brain gene expression data from the Allen Brain Institute collection. Significantly correlated genes were investigated using ingenuity pathway analysis to elucidate molecular pathways. CT but not SA or GMV correlated with expression of 1137 out of 15 633 genes examined controlling for age, sex, and average CT. Among these ≈19%, ≈39%, and 8% of genes were unique to FEAP, schizophrenia, and non-schizophrenia, respectively. Variants of 10 among these 1137 correlated genes previously showed genome-wide-association with schizophrenia. Molecular pathways associated with CT were axonal guidance and sphingosine pathways (common to FEAP and controls), selected inflammation pathways (unique to FEAP), synaptic modulation (unique to schizophrenia), and telomere extension (common to NSZ and healthy controls). We demonstrate that different sets of genes and molecular pathways may preferentially influence CT in different diagnostic groups. Genes with altered expressions correlating with CT and associated pathways may be targets for pathophysiological investigations and novel treatment designs.
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Affiliation(s)
- Bridget N McGuigan
- University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tales Santini
- University of Pittsburgh Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Matcheri S Keshavan
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Konasale M Prasad
- University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- University of Pittsburgh Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Psychiatry, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA, USA
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5
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Mohd Asyraf AJ, Nour El Huda AR, Hanisah MN, Noorul Amilin H, Norlelawati AT. DNA methylation and copy number variation of the complement C4A gene in schizophrenia. GENE REPORTS 2022. [DOI: 10.1016/j.genrep.2022.101702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Sierra DP, Tripathi A, Pillai A. Dysregulation of complement system in neuropsychiatric disorders: A mini review. Biomark Neuropsychiatry 2022; 7. [PMID: 37123465 PMCID: PMC10136364 DOI: 10.1016/j.bionps.2022.100056] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Complement system is one of the most important defense mechanisms of the innate immune system. In addition to their roles in immune regulation, complement proteins are also involved in neurodevelopment and adult brain plasticity. Complement dysregulation has been shown in neurodevelopmental disorders including schizophrenia and autism spectrum disorder as well as in mood disorders. A number of clinical as well as genetic studies suggest the role of complement proteins in the cortical thinning and excessive synaptic pruning frequently associated with schizophrenia. The changes in complement proteins are also associated with the pathophysiology of autism spectrum disorder, major depressive disorder and bipolar disorder, but warrant further research. In addition, rodent models suggest a strong case for complement system in anxiety-like behavior. In this article, we review the recent findings on the role of complement system in neuropsychiatric disorders. The possible uses for future complement targeted therapies are also discussed.
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Affiliation(s)
- Danny Perez Sierra
- Pathophysiology of Neuropsychiatric Disorders Program, Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), Houston, TX, USA
| | - Ashutosh Tripathi
- Pathophysiology of Neuropsychiatric Disorders Program, Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), Houston, TX, USA
| | - Anilkumar Pillai
- Pathophysiology of Neuropsychiatric Disorders Program, Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), Houston, TX, USA
- Research and Development, Charlie Norwood VA Medical Center, Augusta, GA, USA
- Department of Psychiatry and Health Behavior, Medical College of Georgia, Augusta University, Augusta, GA, USA
- Correspondence to: Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, USA. (A. Pillai)
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Evidence that complement and coagulation proteins are mediating the clinical response to omega-3 fatty acids: A mass spectrometry-based investigation in subjects at clinical high-risk for psychosis. Transl Psychiatry 2022; 12:454. [PMID: 36307392 PMCID: PMC9616837 DOI: 10.1038/s41398-022-02217-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 09/21/2022] [Accepted: 10/04/2022] [Indexed: 11/08/2022] Open
Abstract
Preliminary evidence indicates beneficial effects of omega-3 polyunsaturated fatty acids (PUFAs) in early psychosis. The present study investigates the molecular mechanism of omega-3 PUFA-associated therapeutic effects in clinical high-risk (CHR) participants. Plasma samples of 126 CHR psychosis participants at baseline and 6-months follow-up were included. Plasma protein levels were quantified using mass spectrometry and erythrocyte omega-3 PUFA levels were quantified using gas chromatography. We examined the relationship between change in polyunsaturated PUFAs (between baseline and 6-month follow-up) and follow-up plasma proteins. Using mediation analysis, we investigated whether plasma proteins mediated the relationship between change in omega-3 PUFAs and clinical outcomes. A 6-months change in omega-3 PUFAs was associated with 24 plasma proteins at follow-up. Pathway analysis revealed the complement and coagulation pathway as the main biological pathway to be associated with change in omega-3 PUFAs. Moreover, complement and coagulation pathway proteins significantly mediated the relationship between change in omega-3 PUFAs and clinical outcome at follow-up. The inflammatory protein complement C5 and protein S100A9 negatively mediated the relationship between change in omega-3 PUFAs and positive symptom severity, while C5 positively mediated the relationship between change in omega-3 and functional outcome. The relationship between change in omega-3 PUFAs and cognition was positively mediated through coagulation factor V and complement protein C1QB. Our findings provide evidence for a longitudinal association of omega-3 PUFAs with complement and coagulation protein changes in the blood. Further, the results suggest that an increase in omega-3 PUFAs decreases symptom severity and improves cognition in the CHR state through modulating effects of complement and coagulation proteins.
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Dienel SJ, Schoonover KE, Lewis DA. Cognitive Dysfunction and Prefrontal Cortical Circuit Alterations in Schizophrenia: Developmental Trajectories. Biol Psychiatry 2022; 92:450-459. [PMID: 35568522 PMCID: PMC9420748 DOI: 10.1016/j.biopsych.2022.03.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/28/2022] [Accepted: 03/04/2022] [Indexed: 01/01/2023]
Abstract
Individuals with schizophrenia (SZ) exhibit cognitive performance below expected levels based on familial cognitive aptitude. One such cognitive process, working memory (WM), is robustly impaired in SZ. These WM impairments, which emerge over development during the premorbid and prodromal stages of SZ, appear to reflect alterations in the neural circuitry of the dorsolateral prefrontal cortex. Within the dorsolateral prefrontal cortex, a microcircuit formed by reciprocal connections between excitatory layer 3 pyramidal neurons and inhibitory parvalbumin basket cells (PVBCs) appears to be a key neural substrate for WM. Postmortem human studies indicate that both layer 3 pyramidal neurons and PVBCs are altered in SZ, suggesting that levels of excitation and inhibition are lower in the microcircuit. Studies in monkeys indicate that features of both cell types exhibit distinctive postnatal developmental trajectories. Together, the results of these studies suggest a model in which 1) genetic and/or early environmental insults to excitatory signaling in layer 3 pyramidal neurons give rise to cognitive impairments during the prodromal phase of SZ and evoke compensatory changes in inhibition that alter the developmental trajectories of PVBCs, and 2) synaptic pruning during adolescence further lowers excitatory activity to a level that exceeds the compensatory capacity of PVBC inhibition, leading to a failure of the normal maturational improvements in WM during the prodromal and early clinical stages of SZ. Findings that support as well as challenge this model are discussed.
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Affiliation(s)
- Samuel J Dienel
- Translational Neuroscience Program, Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; Medical Scientist Training Program, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania; Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Kirsten E Schoonover
- Translational Neuroscience Program, Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - David A Lewis
- Translational Neuroscience Program, Department of Psychiatry, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania; Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, Pennsylvania.
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Arnsten AFT, Woo E, Yang S, Wang M, Datta D. Unusual Molecular Regulation of Dorsolateral Prefrontal Cortex Layer III Synapses Increases Vulnerability to Genetic and Environmental Insults in Schizophrenia. Biol Psychiatry 2022; 92:480-490. [PMID: 35305820 PMCID: PMC9372235 DOI: 10.1016/j.biopsych.2022.02.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 02/03/2022] [Accepted: 02/06/2022] [Indexed: 02/06/2023]
Abstract
Schizophrenia is associated with reduced numbers of spines and dendrites from layer III of the dorsolateral prefrontal cortex (dlPFC), the layer that houses the recurrent excitatory microcircuits that subserve working memory and abstract thought. Why are these synapses so vulnerable, while synapses in deeper or more superficial layers are little affected? This review describes the special molecular properties that govern layer III neurotransmission and neuromodulation in the primate dlPFC and how they may render these circuits particularly vulnerable to genetic and environmental insults. These properties include a reliance on NMDA receptor rather than AMPA receptor neurotransmission; cAMP (cyclic adenosine monophosphate) magnification of calcium signaling near the glutamatergic synapse of dendritic spines; and potassium channels opened by cAMP/PKA (protein kinase A) signaling that dynamically alter network strength, with built-in mechanisms to take dlPFC "offline" during stress. A variety of genetic and/or environmental insults can lead to the same phenotype of weakened layer III connectivity, in which mechanisms that normally strengthen connectivity are impaired and those that normally weaken connectivity are intensified. Inflammatory mechanisms, such as increased kynurenic acid and glutamate carboxypeptidase II expression, are especially detrimental to layer III dlPFC neurotransmission and modulation, mimicking genetic insults. The combination of genetic and inflammatory insults may cross the threshold into pathology.
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Affiliation(s)
- Amy F T Arnsten
- Department of Neuroscience, Yale Medical School, New Haven, Connecticut.
| | - Elizabeth Woo
- Department of Neuroscience, Yale Medical School, New Haven, Connecticut
| | - Shengtao Yang
- Department of Neuroscience, Yale Medical School, New Haven, Connecticut
| | - Min Wang
- Department of Neuroscience, Yale Medical School, New Haven, Connecticut
| | - Dibyadeep Datta
- Department of Neuroscience, Yale Medical School, New Haven, Connecticut
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Laukka JJ, Kain KM, Rathnam AS, Sohi J, Khatib D, Kamholz J, Stanley JA. Altered high-energy phosphate and membrane metabolism in Pelizaeus–Merzbacher disease using phosphorus magnetic resonance spectroscopy. Brain Commun 2022; 4:fcac202. [PMID: 36003325 PMCID: PMC9396944 DOI: 10.1093/braincomms/fcac202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 06/06/2022] [Accepted: 08/04/2022] [Indexed: 11/14/2022] Open
Abstract
Pelizaeus–Merzbacher disease is an X-linked recessive leucodystrophy of the central nervous system caused by mutations affecting the major myelin protein, proteolipid protein 1. The extent of the altered in vivo neurochemistry of protein, proteolipid protein 1 duplications, the most common form of Pelizaeus–Merzbacher disease, is, however, poorly understood. Phosphorus magnetic resonance spectroscopy is the only in vivo technique that can assess the biochemistry associated with high-energy phosphate and membrane phospholipid metabolism across different cortical, subcortical and white matter areas. In this cross-sectional study, whole-brain, multi-voxel phosphorus magnetic resonance spectroscopy was acquired at 3 T on 14 patients with Pelizaeus–Merzbacher disease with protein, proteolipid protein 1 duplications and 23 healthy controls (all males). Anabolic and catabolic levels of membrane phospholipids (phosphocholine and phosphoethanolamine, and glycerophosphoethanolamine and glycerophosphocholine, respectively), as well as phosphocreatine, inorganic orthophosphate and adenosine triphosphate levels relative to the total phosphorus magnetic resonance spectroscopy signal from 12 different cortical and subcortical areas were compared between the two groups. Independent of brain area, phosphocholine, glycerophosphoethanolamine and inorganic orthophosphate levels were significantly lower (P = 0.0025, P < 0.0001 and P = 0.0002) and phosphocreatine levels were significantly higher (P < 0.0001) in Pelizaeus–Merzbacher disease patients compared with controls. Additionally, there was a significant group-by-brain area interaction for phosphocreatine with post-hoc analyses demonstrating significantly higher phosphocreatine levels in patients with Pelizaeus–Merzbacher disease compared with controls across multiple brain areas (anterior and posterior white matter, superior parietal lobe, posterior cingulate cortex, hippocampus, occipital cortex, striatum and thalamus; all P ≤ 0.0042). Phosphoethanolamine, glycerophosphoethanolamine and adenosine triphosphate levels were not significantly different between groups. For the first-time, widespread alterations in phosphorus magnetic resonance spectroscopy metabolite levels of Pelizaeus–Merzbacher disease patients are being reported. Specifically, increased high-energy phosphate storage levels of phosphocreatine concomitant with decreased inorganic orthophosphate across multiple areas suggest a widespread reduction in the high-energy phosphate utilization in Pelizaeus–Merzbacher disease, and the membrane phospholipid metabolite deficits suggest a widespread degradation in the neuropil content/maintenance of patients with Pelizaeus–Merzbacher disease which includes axons, dendrites and astrocytes within cortex and the myelin microstructure and oligodendrocytes within white matter. These results provide greater insight into the neuropathology of Pelizaeus–Merzbacher disease both in terms of energy expenditure and membrane phospholipid metabolites. Future longitudinal studies are warranted to investigate the utility of phosphorus magnetic resonance spectroscopy as surrogate biomarkers in monitoring treatment intervention for Pelizaeus–Merzbacher disease.
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Affiliation(s)
- Jeremy J Laukka
- Department of Medical Education, University of Toledo College of Medicine and Life Sciences , Toledo, OH , USA
- Department of Neurology, University of Toledo College of Medicine and Life Sciences , Toledo, OH , USA
| | - Kevin M Kain
- College of Osteopathic Medicine, Kansas City University , Kansas City, MO , USA
| | | | - Jasloveleen Sohi
- Department of Neurology, Center for Molecular Medicine and Genetics, Wayne State University School of Medicine , MI , USA
| | - Dalal Khatib
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine , Detroit, MI , USA
| | - John Kamholz
- Department of Neurology, Center for Molecular Medicine and Genetics, Wayne State University School of Medicine , MI , USA
- Department of Neurology, University of Iowa Carver College of Medicine , Iowa City, IA , USA
| | - Jeffrey A Stanley
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine , Detroit, MI , USA
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Li J, Yoshikawa A, Alliey-Rodriguez N, Meltzer HY. Schizophrenia risk loci from xMHC region were associated with antipsychotic response in chronic schizophrenic patients with persistent positive symptom. Transl Psychiatry 2022; 12:92. [PMID: 35250027 PMCID: PMC8898944 DOI: 10.1038/s41398-022-01854-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/17/2021] [Accepted: 02/03/2022] [Indexed: 11/09/2022] Open
Abstract
We examined whether common variants from the extended major histocompatibility complex (xMHC) region contribute to the response to antipsychotic drugs (APDs) in patients with schizophrenia with persistent psychosis. Subjects participated in a prospective longitudinal study of the effect of APDs on psychopathology were temporally split into discovery (n = 88) and replication (n = 42) cohorts. The primary endpoint was a change in Brief Psychiatric Rating Scale at 6-week or 6-month after treatment. rs204991 (β = 3.917, p = 3.72 × 10-6), the strongest signal associated with response at 6-week was located near C4A/C4B after a linear regression adjusted for covariates. xMHC SNP imputation disclosed much stronger signals (rs9268469, β = 5.140, p = 1.57 × 10-7) and other weaker signals (p < 1 × 10-5) spanning the entire xMHC region. All the variants were previously identified schizophrenia risk loci. Conditional fine-mapping revealed three subgroups of SNPs which were the eQTLs (p < 1 × 10-7) for C4A, HLA-C, and BTN3A2 in disease-relevant tissue. Epistasis between HLA-C and C4A was observed (p = 0.019). Minor allele (G) carriers of rs204991, eQTL for C4A, having decreased risk for schizophrenia and lower imputed expression of C4A, had a better response to APDs. Some imputed HLA alleles associated with a decreased risk for schizophrenia had a positive association with improvement in psychotic symptoms. An independent cohort validated the association of change in psychosis with C4A. We provide evidence that genetic risk factors for schizophrenia from the xMHC region are associated with response to APDs and those variants significantly alter the imputed expression of C4A, HLA-C, and BTN3A2. The minor alleles predicting higher C4A level are associated with diminished improvement in psychotic symptoms after APD treatment.
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Affiliation(s)
- Jiang Li
- grid.16753.360000 0001 2299 3507Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL USA ,grid.415341.60000 0004 0433 4040Department of Molecular and Functional Genomics, Weis Center for Research, Geisinger Health System, Danville, PA USA
| | - Akane Yoshikawa
- grid.16753.360000 0001 2299 3507Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL USA ,grid.258269.20000 0004 1762 2738Department of Psychiatry and Behavioral Sciences, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Ney Alliey-Rodriguez
- grid.16753.360000 0001 2299 3507Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL USA
| | - Herbert Y. Meltzer
- grid.16753.360000 0001 2299 3507Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL USA
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12
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Smucny J, Dienel SJ, Lewis DA, Carter CS. Mechanisms underlying dorsolateral prefrontal cortex contributions to cognitive dysfunction in schizophrenia. Neuropsychopharmacology 2022; 47:292-308. [PMID: 34285373 PMCID: PMC8617156 DOI: 10.1038/s41386-021-01089-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 06/25/2021] [Accepted: 06/28/2021] [Indexed: 02/07/2023]
Abstract
Kraepelin, in his early descriptions of schizophrenia (SZ), characterized the illness as having "an orchestra without a conductor." Kraepelin further speculated that this "conductor" was situated in the frontal lobes. Findings from multiple studies over the following decades have clearly implicated pathology of the dorsolateral prefrontal cortex (DLPFC) as playing a central role in the pathophysiology of SZ, particularly with regard to key cognitive features such as deficits in working memory and cognitive control. Following an overview of the cognitive mechanisms associated with DLPFC function and how they are altered in SZ, we review evidence from an array of neuroscientific approaches addressing how these cognitive impairments may reflect the underlying pathophysiology of the illness. Specifically, we present evidence suggesting that alterations of the DLPFC in SZ are evident across a range of spatial and temporal resolutions: from its cellular and molecular architecture, to its gross structural and functional integrity, and from millisecond to longer timescales. We then present an integrative model based upon how microscale changes in neuronal signaling in the DLPFC can influence synchronized patterns of neural activity to produce macrocircuit-level alterations in DLPFC activation that ultimately influence cognition and behavior. We conclude with a discussion of initial efforts aimed at targeting DLPFC function in SZ, the clinical implications of those efforts, and potential avenues for future development.
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Affiliation(s)
- Jason Smucny
- Department of Psychiatry and Behavioral Sciences, University of California Davis Medical Center, Sacramento, CA, USA
- Center for Neuroscience, University of California Davis, Davis, CA, USA
| | - Samuel J Dienel
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - David A Lewis
- Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA.
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Cameron S Carter
- Department of Psychiatry and Behavioral Sciences, University of California Davis Medical Center, Sacramento, CA, USA.
- Center for Neuroscience, University of California Davis, Davis, CA, USA.
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13
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Dysbiosis, gut-blood barrier rupture and autoimmune response in rheumatoid arthritis and schizophrenia. Reumatologia 2021; 59:180-187. [PMID: 34538945 PMCID: PMC8436801 DOI: 10.5114/reum.2021.107588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/17/2021] [Indexed: 12/14/2022] Open
Abstract
The primary cause of chronic autoimmune diseases is elusive both in somatic medicine and psychiatry. Examples of such conditions are rheumatoid arthritis and schizophrenic disorders. Immune disturbances occur in both diseases, but it is difficult to combine them into a meaningful pathogenetic model. The immunological hypothesis of schizophrenia is based on non-specific changes in the cytokine system and exponents of chronic inflammation in some patients. In rheumatoid arthritis the cytokine network is much better known than in schizophrenia, and interleukin-6, tumor necrosis factor or Janus kinases became a target of treatment. Microbiome dysbiosis and disturbances of the blood–gut barrier may be a new hypothesis of the pathogenesis of somatic and psychiatric diseases. The purpose of this narrative review was to show, using the example of two chronic diseases – rheumatoid arthritis and schizophrenic disorders – that disturbances in the blood barrier of the intestine can be a common mechanism of somatic and mental disorders. The paper presents the current state of knowledge on the hypothetical relationship between microbiome dysbiosis and the pathogenesis of schizophrenia and rheumatoid arthritis. In conclusion, in the light of discoveries regarding the microbiome–gut–brain axis the immunological model of rheumatoid arthritis and schizophrenia formation may gain importance and contribute to the creation of new strategies for causal treatment of these still incurable diseases.
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14
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Severance EG, Leister F, Lea A, Yang S, Dickerson F, Yolken RH. Complement C4 associations with altered microbial biomarkers exemplify gene-by-environment interactions in schizophrenia. Schizophr Res 2021; 234:87-93. [PMID: 33632634 PMCID: PMC8373622 DOI: 10.1016/j.schres.2021.02.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 02/04/2021] [Accepted: 02/08/2021] [Indexed: 12/18/2022]
Abstract
Schizophrenia is a complex brain disorder with genetic and environmental factors contributing to its etiology. Complement C4 genes are schizophrenia susceptibility loci and are activated in response to infections and gut microbiome imbalances. We hypothesize that C4 genetic susceptibility predisposes individuals to neuropathological effects from pathogen exposures or a microbiome in dysbiosis. In 214 individuals with schizophrenia and 123 non-psychiatric controls, we examined C4 gene copy number and haplotype groups for associations with schizophrenia and microbial plasma biomarkers. C4A copy number and haplotypes containing HERV-K insertions (C4A-long; C4AL-C4AL) conferred elevated odds ratios for schizophrenia diagnoses (OR 1.58-2.56, p < 0.0001), while C4B-short (C4BS) haplogroups conferred decreased odds (OR 0.43, p < 0.0001). Haplogroup-microbe combinations showed extensive associations with schizophrenia including C4AL with Candida albicans IgG (OR 2.16, p < 0.0005), C4AL-C4BL with cytomegalovirus (CMV) IgG (OR 1.79, p < 0.008), C4BS with lipopolysaccharide-binding protein (LBP) (OR 1.18, p < 0.0001), and C4AL-C4AL with Toxoplasma gondii IgG (OR = 17.67, p < 0.0001). In controls, only one haplogroup-microbe combination was significant: C4BS with CMV IgG (OR 0.52, p < 0.02). In schizophrenia only, LBP and CMV IgG levels were inversely correlated with C4A and C4S copy numbers, respectively (R2 = 0.13-0.16, p < 0.0001). C4 haplogroups were associated with altered scores of cognitive functioning in both cases and controls and with psychiatric symptom scores in schizophrenia. Our findings link complement C4 genes with a susceptibility to infections and a dysbiotic microbiome in schizophrenia. These results support immune system mechanisms by which gene-environmental interactions may be operative in schizophrenia.
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Affiliation(s)
- Emily G Severance
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| | - Flora Leister
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ashley Lea
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Shuojia Yang
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | | | - Robert H Yolken
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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15
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Prasad KM. Infectious agents as risk factors for psychosis - A time to reconsider and reinvigorate investigations. Schizophr Res 2021; 233:111-113. [PMID: 34325962 DOI: 10.1016/j.schres.2021.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Accepted: 07/10/2021] [Indexed: 11/18/2022]
Affiliation(s)
- Konasale M Prasad
- Department of Psychiatry and Bioengineering, University of Pittsburgh School of Medicine and Swanson School of Engineering, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA 15213, USA.
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16
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Elevated expression of complement C4 in the mouse prefrontal cortex causes schizophrenia-associated phenotypes. Mol Psychiatry 2021; 26:3489-3501. [PMID: 33837272 DOI: 10.1038/s41380-021-01081-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 03/05/2021] [Accepted: 03/26/2021] [Indexed: 12/18/2022]
Abstract
Accumulating evidence supports immune involvement in the pathogenesis of schizophrenia, a severe psychiatric disorder. In particular, high expression variants of C4, a gene of the innate immune complement system, were shown to confer susceptibility to schizophrenia. However, how elevated C4 expression may impact brain circuits remains largely unknown. We used in utero electroporation to overexpress C4 in the mouse prefrontal cortex. We found reduced glutamatergic input to pyramidal cells of juvenile and adult, but not of newborn C4-overexpressing (C4-OE) mice, together with decreased spine density, which mirrors spine loss observed in the schizophrenic cortex. Using time-lapse two-photon imaging in vivo, we observed that these deficits were associated with decreased dendritic spine gain and elimination in juvenile C4-OE mice, which may reflect poor formation and/or stabilization of immature spines. In juvenile and adult C4-OE mice, we found evidence for NMDA receptor hypofunction, another schizophrenia-associated phenotype, and synaptic accumulation of calcium-permeable AMPA receptors. Alterations in cortical GABAergic networks have been repeatedly associated with schizophrenia. We found that functional GABAergic transmission was reduced in C4-OE mice, in line with diminished GABA release probability from parvalbumin interneurons, lower GAD67 expression, and decreased intrinsic excitability in parvalbumin interneurons. These cellular abnormalities were associated with working memory impairment. Our results substantiate the causal relationship between an immunogenetic risk factor and several distinct cortical endophenotypes of schizophrenia and shed light on the underlying cellular mechanisms.
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17
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Ziabska K, Ziemka-Nalecz M, Pawelec P, Sypecka J, Zalewska T. Aberrant Complement System Activation in Neurological Disorders. Int J Mol Sci 2021; 22:4675. [PMID: 33925147 PMCID: PMC8125564 DOI: 10.3390/ijms22094675] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/22/2021] [Accepted: 04/26/2021] [Indexed: 12/13/2022] Open
Abstract
The complement system is an assembly of proteins that collectively participate in the functions of the healthy and diseased brain. The complement system plays an important role in the maintenance of uninjured (healthy) brain homeostasis, contributing to the clearance of invading pathogens and apoptotic cells, and limiting the inflammatory immune response. However, overactivation or underregulation of the entire complement cascade within the brain may lead to neuronal damage and disturbances in brain function. During the last decade, there has been a growing interest in the role that this cascading pathway plays in the neuropathology of a diverse array of brain disorders (e.g., acute neurotraumatic insult, chronic neurodegenerative diseases, and psychiatric disturbances) in which interruption of neuronal homeostasis triggers complement activation. Dysfunction of the complement promotes a disease-specific response that may have either beneficial or detrimental effects. Despite recent advances, the explicit link between complement component regulation and brain disorders remains unclear. Therefore, a comprehensible understanding of such relationships at different stages of diseases could provide new insight into potential therapeutic targets to ameliorate or slow progression of currently intractable disorders in the nervous system. Hence, the aim of this review is to provide a summary of the literature on the emerging role of the complement system in certain brain disorders.
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Affiliation(s)
| | | | | | | | - Teresa Zalewska
- Mossakowski Medical Research Centre, NeuroRepair Department, Polish Academy of Sciences, 5 Pawinskiego Street, 02-106 Warsaw, Poland; (K.Z.); (M.Z.-N.); (P.P.); (J.S.)
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18
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Bergersen KV, Barnes A, Worth D, David C, Wilson EH. Targeted Transcriptomic Analysis of C57BL/6 and BALB/c Mice During Progressive Chronic Toxoplasma gondii Infection Reveals Changes in Host and Parasite Gene Expression Relating to Neuropathology and Resolution. Front Cell Infect Microbiol 2021; 11:645778. [PMID: 33816350 PMCID: PMC8012756 DOI: 10.3389/fcimb.2021.645778] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 02/23/2021] [Indexed: 02/06/2023] Open
Abstract
Toxoplasma gondii is a resilient parasite that infects a multitude of warm-blooded hosts and results in a lifelong chronic infection requiring continuous responses by the host. Chronic infection is characterized by a balanced immune response and neuropathology that are driven by changes in gene expression. Previous research pertaining to these processes has been conducted in various mouse models, and much knowledge of infection-induced gene expression changes has been acquired through the use of high throughput sequencing techniques in different mouse strains and post-mortem human studies. However, lack of infection time course data poses a prominent missing link in the understanding of chronic infection, and there is still much that is unknown regarding changes in genes specifically relating to neuropathology and resulting repair mechanisms as infection progresses throughout the different stages of chronicity. In this paper, we present a targeted approach to gene expression analysis during T. gondii infection through the use of NanoString nCounter gene expression assays. Wild type C57BL/6 and BALB/c background mice were infected, and transcriptional changes in the brain were evaluated at 14, 28, and 56 days post infection. Results demonstrate a dramatic shift in both previously demonstrated and novel gene expression relating to neuropathology and resolution in C57BL/6 mice. In addition, comparison between BALB/c and C57BL/6 mice demonstrate initial differences in gene expression that evolve over the course of infection and indicate decreased neuropathology and enhanced repair in BALB/c mice. In conclusion, these studies provide a targeted approach to gene expression analysis in the brain during infection and provide elaboration on previously identified transcriptional changes and also offer insights into further understanding the complexities of chronic T. gondii infection.
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Affiliation(s)
- Kristina V Bergersen
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Ashli Barnes
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Danielle Worth
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Clement David
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States.,NanoString Technologies, Seattle, WA, United States
| | - Emma H Wilson
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
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19
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Schizophrenia: Complement Cleaning or Killing. Genes (Basel) 2021; 12:genes12020259. [PMID: 33670154 PMCID: PMC7916832 DOI: 10.3390/genes12020259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 12/12/2022] Open
Abstract
Schizophrenia is a psychiatric disorder with a typical onset occurring during adolescence or young adulthood. The heterogeneity of the disorder complicates our understanding of the pathophysiology. Reduced cortical synaptic densities are commonly observed in schizophrenia and suggest a role for excessive synaptic elimination. A major pathway hypothesised to eliminate synapses during postnatal development is the complement system. This review provides an overview of genetic and functional evidence found for the individual players of the classical complement pathway. In addition, the consequences of the absence of complement proteins, in the form of complement protein deficiencies in humans, are taken into consideration. The collective data provide strong evidence for excessive pruning by the classical complement pathway, contributing to cognitive impairment in schizophrenia. In future studies, it will be important to assess the magnitude of the contribution of complement overactivity to the occurrence and prevalence of phenotypic features in schizophrenia. In addition, more insight is required for the exact mechanisms by which the complement system causes excessive pruning, such as the suggested involvement of microglial engulfment and degradation of synapses. Ultimately, this knowledge is a prerequisite for the development of therapeutic interventions for selective groups of schizophrenia patients.
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20
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Rey R, Suaud-Chagny MF, Bohec AL, Dorey JM, d'Amato T, Tamouza R, Leboyer M. Overexpression of complement component C4 in the dorsolateral prefrontal cortex, parietal cortex, superior temporal gyrus and associative striatum of patients with schizophrenia. Brain Behav Immun 2020; 90:216-225. [PMID: 32827700 DOI: 10.1016/j.bbi.2020.08.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 08/10/2020] [Accepted: 08/17/2020] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND In schizophrenia, abnormal synaptic pruning during adolescence may be due to altered expression of the Complement component 4 (C4). Overexpression of C4 genes has been identified in the total cerebral cortex and in 6 different brain regions of schizophrenic patients compared to controls. These alterations should be replicated and extended to other brain regions relevant to schizophrenia. Moreover, it remains unknown whether cerebral and peripheral C4 expression levels are related. METHODS We explored C4 genes expression both at the cerebral and peripheral levels. Using shinyGEO application we analyzed C4 expression from eight Gene Expression Omnibus datasets obtained from 196 schizophrenic patients and 182 control subjects. First, we compared C4 expression between schizophrenic patients and controls in postmortem cerebral samples from 7 different brain regions. Then, we compared C4 expression between schizophrenic patients and controls in 4 peripheral tissues. RESULTS At the cerebral level, we provide further evidence of C4 overexpression in schizophrenic patients. Consistently with a previous report, we found C4 overexpression in the dorsolateral prefrontal cortex and in the parietal cortex of schizophrenic patients. The observation of C4 overexpression was further extended to the superior temporal cortex and the associative striatum of schizophrenic patients. Conversely, no significant alteration of C4 expression was observed in peripheral tissues. CONCLUSIONS Our results support the hypothesis of an excessive Complement activity in various brain regions of schizophrenic patients which may disrupt the synaptic pruning process occurring during adolescence. C4 overexpression may be specific to the cerebral tissue while other alterations of the Complement system may be detected at the systemic level.
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Affiliation(s)
- Romain Rey
- INSERM, U1028, CNRS, UMR5292, Lyon Neuroscience Research Center, Psychiatric Disorders: from Resistance to Response Team, Lyon F-69000, France; University Lyon 1, Villeurbanne F-69000, France; Schizophrenia Expert Centre, Le Vinatier Hospital, Bron, France; Fondation FondaMental, Créteil, France.
| | - Marie-Françoise Suaud-Chagny
- INSERM, U1028, CNRS, UMR5292, Lyon Neuroscience Research Center, Psychiatric Disorders: from Resistance to Response Team, Lyon F-69000, France; University Lyon 1, Villeurbanne F-69000, France
| | - Anne-Lise Bohec
- INSERM, U1028, CNRS, UMR5292, Lyon Neuroscience Research Center, Psychiatric Disorders: from Resistance to Response Team, Lyon F-69000, France; University Lyon 1, Villeurbanne F-69000, France; Schizophrenia Expert Centre, Le Vinatier Hospital, Bron, France; Fondation FondaMental, Créteil, France
| | - Jean-Michel Dorey
- University Lyon 1, Villeurbanne F-69000, France; Department of Old Age Psychiatry, Le Vinatier Hospital, Bron, France
| | - Thierry d'Amato
- INSERM, U1028, CNRS, UMR5292, Lyon Neuroscience Research Center, Psychiatric Disorders: from Resistance to Response Team, Lyon F-69000, France; University Lyon 1, Villeurbanne F-69000, France; Schizophrenia Expert Centre, Le Vinatier Hospital, Bron, France; Fondation FondaMental, Créteil, France
| | - Ryad Tamouza
- Fondation FondaMental, Créteil, France; Department of Psychiatry and Addictology, Mondor University Hospital, AP-HP, DMU IMPACT, France; University Paris-Est-Créteil, UPEC, Créteil, France; Inserm U955, Mondor Institute for Biomedical Research, IMRB, Translational Neuropsychiatry Team, Créteil, France
| | - Marion Leboyer
- Fondation FondaMental, Créteil, France; Department of Psychiatry and Addictology, Mondor University Hospital, AP-HP, DMU IMPACT, France; University Paris-Est-Créteil, UPEC, Créteil, France; Inserm U955, Mondor Institute for Biomedical Research, IMRB, Translational Neuropsychiatry Team, Créteil, France
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21
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Abstract
Purpose of Review A better understanding of the key molecules/pathways underlying the pathophysiology of depression and schizophrenia may contribute to novel therapeutic strategies. In this review, we have discussed the recent developments on the role of inflammatory pathways in the pathogenesis of depression and schizophrenia. Recent Findings Inflammation is an innate immune response that can be triggered by various factors, including pathogens, stress and injury. Under normal conditions, the inflammatory responses quiet after pathogen clearance and tissue repair. However, abnormal long-term or chronic inflammation can lead to damaging effects. Accumulating evidence suggest that dysregulated inflammation is linked to the pathogenesis of neuropsychiatric disorders. In this review, we have discussed the roles of complement system, infiltration of peripheral immune cells into the central nervous system (CNS), the gut-brain axis, and the kynurenine pathway in depression and schizophrenia. Summary There is a large body of compelling evidence on the role of inflammatory pathways in depression and schizophrenia. Although most of these findings show their roles in the pathophysiology of the above disorders, additional studies are warranted to investigate the therapeutic potential of various immune signaling targets discussed in this article.
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22
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Cardozo PL, de Lima IBQ, Maciel EMA, Silva NC, Dobransky T, Ribeiro FM. Synaptic Elimination in Neurological Disorders. Curr Neuropharmacol 2020; 17:1071-1095. [PMID: 31161981 PMCID: PMC7052824 DOI: 10.2174/1570159x17666190603170511] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/23/2019] [Accepted: 05/31/2019] [Indexed: 12/12/2022] Open
Abstract
Synapses are well known as the main structures responsible for transmitting information through the release and recognition of neurotransmitters by pre- and post-synaptic neurons. These structures are widely formed and eliminated throughout the whole lifespan via processes termed synaptogenesis and synaptic pruning, respectively. Whilst the first pro-cess is needed for ensuring proper connectivity between brain regions and also with the periphery, the second phenomenon is important for their refinement by eliminating weaker and unnecessary synapses and, at the same time, maintaining and fa-voring the stronger ones, thus ensuring proper synaptic transmission. It is well-known that synaptic elimination is modulated by neuronal activity. However, only recently the role of the classical complement cascade in promoting this phenomenon has been demonstrated. Specifically, microglial cells recognize activated complement component 3 (C3) bound to synapses tar-geted for elimination, triggering their engulfment. As this is a highly relevant process for adequate neuronal functioning, dis-ruptions or exacerbations in synaptic pruning could lead to severe circuitry alterations that could underlie neuropathological alterations typical of neurological and neuropsychiatric disorders. In this review, we focus on discussing the possible in-volvement of excessive synaptic elimination in Alzheimer’s disease, as it has already been reported dendritic spine loss in post-synaptic neurons, increased association of complement proteins with its synapses and, hence, augmented microglia-mediated pruning in animal models of this disorder. In addition, we briefly discuss how this phenomenon could be related to other neurological disorders, including multiple sclerosis and schizophrenia.
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Affiliation(s)
- Pablo L Cardozo
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Izabella B Q de Lima
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Esther M A Maciel
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Nathália C Silva
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | | | - Fabíola M Ribeiro
- Laboratório de Neurobioquímica, Departamento de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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23
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Magdalon J, Mansur F, Teles E Silva AL, de Goes VA, Reiner O, Sertié AL. Complement System in Brain Architecture and Neurodevelopmental Disorders. Front Neurosci 2020; 14:23. [PMID: 32116493 PMCID: PMC7015047 DOI: 10.3389/fnins.2020.00023] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/10/2020] [Indexed: 01/18/2023] Open
Abstract
Current evidence indicates that certain immune molecules such as components of the complement system are directly involved in neurobiological processes related to brain development, including neurogenesis, neuronal migration, synaptic remodeling, and response to prenatal or early postnatal brain insults. Consequently, complement system dysfunction has been increasingly implicated in disorders of neurodevelopmental origin, such as schizophrenia, autism spectrum disorder (ASD) and Rett syndrome. However, the mechanistic evidence for a causal relationship between impaired complement regulation and these disorders varies depending on the disease involved. Also, it is still unclear to what extent altered complement expression plays a role in these disorders through inflammation-independent or -dependent mechanisms. Furthermore, pathogenic mutations in specific complement components have been implicated in the etiology of 3MC syndrome, a rare autosomal recessive developmental disorder. The aims of this review are to discuss the current knowledge on the roles of the complement system in sculpting brain architecture and function during normal development as well as after specific inflammatory insults, such as maternal immune activation (MIA) during pregnancy, and to evaluate the existing evidence associating aberrant complement with developmental brain disorders.
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Affiliation(s)
- Juliana Magdalon
- Center for Experimental Research, Hospital Israelita Albert Einstein, São Paulo, Brazil.,School of Medicine, Faculdade Israelita de Ciências da Saúde Albert Einstein, São Paulo, Brazil
| | - Fernanda Mansur
- Center for Experimental Research, Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - André Luiz Teles E Silva
- Center for Experimental Research, Hospital Israelita Albert Einstein, São Paulo, Brazil.,Department of Genetics and Evolutionary Biology, University of São Paulo, São Paulo, Brazil
| | - Vitor Abreu de Goes
- Center for Experimental Research, Hospital Israelita Albert Einstein, São Paulo, Brazil.,School of Medicine, Faculdade Israelita de Ciências da Saúde Albert Einstein, São Paulo, Brazil
| | - Orly Reiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Andréa Laurato Sertié
- Center for Experimental Research, Hospital Israelita Albert Einstein, São Paulo, Brazil
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24
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Keshavan M, Lizano P, Prasad K. The synaptic pruning hypothesis of schizophrenia: promises and challenges. World Psychiatry 2020; 19:110-111. [PMID: 31922664 PMCID: PMC6953570 DOI: 10.1002/wps.20725] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Matcheri Keshavan
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Paulo Lizano
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Konasale Prasad
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA,Department of Bioengineering, Swanson School of Engineering, Pittsburgh, PA, USA,Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA, USA
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25
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Pape K, Tamouza R, Leboyer M, Zipp F. Immunoneuropsychiatry - novel perspectives on brain disorders. Nat Rev Neurol 2020; 15:317-328. [PMID: 30988501 DOI: 10.1038/s41582-019-0174-4] [Citation(s) in RCA: 259] [Impact Index Per Article: 64.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Immune processes have a vital role in CNS homeostasis, resilience and brain reserve. Our cognitive and social abilities rely on a highly sensitive and fine-tuned equilibrium of immune responses that involve both innate and adaptive immunity. Autoimmunity, chronic inflammation, infection and psychosocial stress can tip the scales towards disruption of higher-order networks. However, not only classical neuroinflammatory diseases, such as multiple sclerosis and autoimmune encephalitis, are caused by immune dysregulation that affects CNS function. Recent insight indicates that similar processes are involved in psychiatric diseases such as schizophrenia, autism spectrum disorder, bipolar disorder and depression. Pathways that are common to these disorders include microglial activation, pro-inflammatory cytokines, molecular mimicry, anti-neuronal autoantibodies, self-reactive T cells and disturbance of the blood-brain barrier. These discoveries challenge our traditional classification of neurological and psychiatric diseases. New clinical paths are required to identify subgroups of neuropsychiatric disorders that are phenotypically distinct but pathogenically related and to pave the way for mechanism-based immune treatments. Combined expertise from neurologists and psychiatrists will foster translation of these paths into clinical practice. The aim of this Review is to highlight outstanding findings that have transformed our understanding of neuropsychiatric diseases and to suggest new diagnostic and therapeutic criteria for the emerging field of immunoneuropsychiatry.
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Affiliation(s)
- Katrin Pape
- Department of Neurology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
| | - Ryad Tamouza
- Inserm, U955, Institut Mondor de la Recherche Biomédicale, Créteil, France.,Fondation FondaMental, Créteil, France.,AP-HP, Department of Psychiatry of Mondor University Hospital, DHU PePsy, University of Paris-Est-Créteil, Créteil, France
| | - Marion Leboyer
- Inserm, U955, Institut Mondor de la Recherche Biomédicale, Créteil, France.,Fondation FondaMental, Créteil, France.,AP-HP, Department of Psychiatry of Mondor University Hospital, DHU PePsy, University of Paris-Est-Créteil, Créteil, France
| | - Frauke Zipp
- Department of Neurology, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany.
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26
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Haszto CS, Stanley JA, Iyengar S, Prasad KM. Regionally Distinct Alterations in Membrane Phospholipid Metabolism in Schizophrenia: A Meta-analysis of Phosphorus Magnetic Resonance Spectroscopy Studies. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2019; 5:264-280. [PMID: 31748123 DOI: 10.1016/j.bpsc.2019.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 09/12/2019] [Accepted: 09/13/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND Existing data on altered membrane phospholipid metabolism in schizophrenia are diverse. We conducted a meta-analysis of studies of phosphorus magnetic resonance spectroscopy, a noninvasive imaging approach that can assess molecular biochemistry of cortex by measuring phosphomonoester (PME) and phosphodiester (PDE) levels, which can provide evidence of altered biochemical processes involved in neuropil membrane expansion and contraction in schizophrenia. METHODS We analyzed PME and PDE data in the frontal and temporal lobes in subjects with schizophrenia from 24 peer-reviewed publications using the MAVIS package in R by building random- and fixed-effects models. Heterogeneity of effect sizes, effects of publication bias, and file drawer analysis were also assessed. RESULTS Subjects with schizophrenia showed lower PME levels in the frontal regions (p = .008) and elevated PDE levels in the temporal regions (p < .001) with significant heterogeneity. We noted significant publication bias and file drawer effect for frontal PME and PDE and temporal PDE levels, but not for temporal PME levels. Fail-safe analysis estimated that a high number of negative studies were required to provide nonsignificant results. CONCLUSIONS Despite methodological differences, these phosphorus magnetic resonance spectroscopy studies demonstrate regionally specific imbalance in membrane phospholipid metabolism related to neuropil in subjects with schizophrenia compared with control subjects reflecting neuropil contraction. Specifically, decreased PME levels in the frontal regions and elevated PDE levels in the temporal regions provide evidence of decreased synthesis and increased degradation of neuropil membrane, respectively. Notwithstanding significant heterogeneity and publication bias, a large number of negative studies are required to render the results of this meta-analysis nonsignificant. These findings warrant further postmortem and animal studies.
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Affiliation(s)
- Connor S Haszto
- Kenneth Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jeffrey A Stanley
- Department of Psychiatry and Behavioral Neuroscience, Wayne State University School of Medicine, Detroit, Michigan
| | - Satish Iyengar
- Department of Statistics, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Konasale M Prasad
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; Veterans Affairs Pittsburgh Health System, Pittsburgh, Pennsylvania.
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27
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Lizano P, Prasad KM, Keshavan MS. Commentary: Do Complement factors "connect the dots" in schizophrenia? Schizophr Res 2019; 204:4-6. [PMID: 30658868 PMCID: PMC6585448 DOI: 10.1016/j.schres.2018.12.042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Paulo Lizano
- Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave KS253, Boston, MA 02215, United States of America.
| | - Konasale M. Prasad
- Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213,For correspondence: Ste 279, 3811 O’Hara St, Pittsburgh, PA 15213,
| | - Matcheri S. Keshavan
- Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Ave KS253, Boston, MA 02215, 617 667 4074
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28
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Abstract
The notion of immunological pathways playing a role in the etiology of a subset of psychotic disorders has received increased interest in the last decades. One of the findings that has spiked interest herein, is an apparent link between autoimmune diseases and psychotic disorders. This is supported by genetic findings associating immune-related genetic markers with schizophrenia and clinical studies finding increased levels of inflammatory markers in patients with psychosis. Several large-scale epidemiologic studies have found positive associations between autoimmune diseases and psychosis. Particularly, autoimmune diseases as multiple sclerosis and lupus are known to have higher frequencies of neuropsychiatric symptoms, including psychosis, compared to healthy controls. Cross sectional studies have found higher prevalence of psychiatric diagnoses among those with autoimmune diseases, and longitudinal studies have shown bidirectional associations between several autoimmune diseases and increased risks associated with schizophrenia. Moreover, a family history of autoimmune diseases has been shown to be associated with an increased risk of psychotic disorders and vice versa. In this review we will summarize the epidemiologic evidence on associations between autoimmune diseases and psychosis. Possible mechanisms accountable for the association will be discussed, amongst others the probable role of shared genetic risk factors, the impact of infections on both autoimmunity and the development of psychotic disorders, and the potential role of the microbiome. We discuss the findings on and influence of autoantibodies and dysregulation of T- and B-cells in both disease categories, and why further research hereon is needed. In addition to the potential importance of autoimmunity in etiological mechanisms of psychotic disorders, the association also brings important attention to somatic comorbidity in patients with psychotic disorders.
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Affiliation(s)
- Rose Jeppesen
- Mental Health Centre Copenhagen, Gentofte Hospital, Copenhagen University Hospital, Hellerup, Denmark
| | - Michael Eriksen Benros
- Mental Health Centre Copenhagen, Gentofte Hospital, Copenhagen University Hospital, Hellerup, Denmark
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29
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Druart M, Le Magueresse C. Emerging Roles of Complement in Psychiatric Disorders. Front Psychiatry 2019; 10:573. [PMID: 31496960 PMCID: PMC6712161 DOI: 10.3389/fpsyt.2019.00573] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 07/22/2019] [Indexed: 12/12/2022] Open
Abstract
The complement system consists of more than 30 proteins that have long been known to participate to the immune defence against pathogens and to the removal of damaged cells. Their role, however, extends beyond immunity and clearance of altered "self" components in the periphery. In particular, complement proteins can be induced by all cell types in the brain. Recent discoveries highlight the role of complement in normal and pathological brain development. Specifically, the complement system mediates synaptic pruning, a developmental process whereby supernumerary synapses are eliminated in the immature brain. The complement system has been implicated in pathological synapse elimination in schizophrenia, West Nile virus infection, and lupus, all of which are associated with psychiatric manifestations. Complement also contributes to synapse loss in neurodegenerative conditions. This review provides a brief overview of the well-studied role of complement molecules in immunity. The contribution of complement to embryonic and adult neurogenesis, neuronal migration, and developmental synaptic elimination in the normal brain is reviewed. We discuss the role of complement in synapse loss in psychiatric and neurological diseases and evaluate the therapeutic potential of complement-targeting drugs for brain disorders.
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Affiliation(s)
- Mélanie Druart
- INSERM UMR-S 1270, Paris, France.,Science and Engineering Faculty, Sorbonne Université, Paris, France.,Institut du Fer à Moulin, Paris, France
| | - Corentin Le Magueresse
- INSERM UMR-S 1270, Paris, France.,Science and Engineering Faculty, Sorbonne Université, Paris, France.,Institut du Fer à Moulin, Paris, France
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30
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Severance EG, Yolken RH. Deciphering microbiome and neuroactive immune gene interactions in schizophrenia. Neurobiol Dis 2018; 135:104331. [PMID: 30471416 DOI: 10.1016/j.nbd.2018.11.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 10/29/2018] [Accepted: 11/19/2018] [Indexed: 02/07/2023] Open
Abstract
The body's microbiome represents an actively regulated network of novel mechanisms that potentially underlie the etiology and pathophysiology of a wide range of diseases. For complex brain disorders such as schizophrenia, understanding the cellular and molecular pathways that intersect the bidirectional gut-brain axis is anticipated to lead to new methods of treatment. The means by which the microbiome might differ across neuropsychiatric and neurological disorders are not known. Brain disorders as diverse as schizophrenia, major depression, Parkinson's disease and multiple sclerosis appear to share a common pathology of an imbalanced community of commensal microbiota, often measured in terms of a leaky gut phenotype accompanied by low level systemic inflammation. While environmental factors associated with these disease states might contribute to intestinal pathologies, products from a perturbed microbiome may also directly promote specific signs, symptoms and etiologies of individual disorders. We hypothesize that in schizophrenia, it is the putatively unique susceptibility related to genes that modulate the immune system and the gut-brain pleiotropy of these genes which leads to a particularly neuropathological response when challenged by a microbiome in dysbiosis. Consequences from exposure to this dysbiosis may occur during pre- or post-natal time periods and thus may interfere with normal neurodevelopment in those who are genetically predisposed. Here, we review the evidence from the literature which supports the idea that the intersection of the microbiome and immune gene susceptibility in schizophrenia is relevant etiologically and for disease progression. Figuring prominently at both ends of the gut-brain axis and at points in between are proteins encoded by genes found in the major histocompatibility complex (MHC), including select MHC as well as non-MHC complement pathway genes.
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Affiliation(s)
- Emily G Severance
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
| | - Robert H Yolken
- Stanley Division of Developmental Neurovirology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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