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Reale M, Costantini E, Greig NH. Cytokine Imbalance in Schizophrenia. From Research to Clinic: Potential Implications for Treatment. Front Psychiatry 2021; 12:536257. [PMID: 33746786 PMCID: PMC7973221 DOI: 10.3389/fpsyt.2021.536257] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 01/18/2021] [Indexed: 12/13/2022] Open
Abstract
Cytokines are one of the most important components of the immune system. They orchestrate the brain's response to infectious and other exogenous insults and are crucial mediators of the cross-talk between the nervous and immune systems. Epidemiological studies have demonstrated that severe infections and autoimmune disorders, in addition to genetic predisposition, are risk factors for schizophrenia. Furthermore, maternal infection during pregnancy appears to increase the risk of schizophrenia, and proinflammatory cytokines may be negatively involved in the neurodevelopmental process. A cytokine imbalance has been described in the blood and cerebrospinal fluid of schizophrenia patients, particularly in the T helper type 1 [Th1] and type 2 [Th2] cytokines, albeit the results of such studies appear to be contradictory. Chronic stress, likewise, appears to contribute to a lasting proinflammatory state and likely also promotes the disorder. The aim of this mini-review is to investigate the roles of different cytokines in the pathophysiology of schizophrenia and define how cytokines may represent key molecular targets to regulate for the prevention and treatment of schizophrenia. How current antipsychotic drugs impact cytokine networks is also evaluated. In this context, we propose to change the focus of schizophrenia from a traditionally defined brain disorder, to one that is substantially impacted by the periphery and immune system.
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Affiliation(s)
- Marcella Reale
- Department of Medical, Oral and Biotechnological Sciences, University "G. d'Annunzio" Chieti-Pescara, Chieti, Italy
| | - Erica Costantini
- Department of Medical, Oral and Biotechnological Sciences, University "G. d'Annunzio" Chieti-Pescara, Chieti, Italy
| | - Nigel H Greig
- Drug Design and Development Section, Translational Gerontology Branch, Intramural Research Program, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
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Dahan S, Bragazzi NL, Yogev A, Bar-Gad M, Barak V, Amital H, Amital D. The relationship between serum cytokine levels and degree of psychosis in patients with schizophrenia. Psychiatry Res 2018; 268:467-472. [PMID: 30138859 DOI: 10.1016/j.psychres.2018.07.041] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 06/02/2018] [Accepted: 07/29/2018] [Indexed: 10/28/2022]
Abstract
Several observations indicate that cytokine concentrations might also relate to the severity of the psychosis. In this study we assessed whether inflammatory and anti-inflammatory cytokine concentrations are associated with the degree of the psychotic manifestations. A group of 41 patients with schizophrenia suffering from an acute psychosis leading to hospitalization in a psychiatric ward were assessed for the intensity of their psychotic manifestations by the PANSS score. Serum IL-2R, IL-6, IL-8, IL-10 were analyzed by commercial ELISA kits. These patients were compared to controls without schizophrenia. At the univariate analysis, statistically significant elevated levels of the cytokines IL-6, IL-2R and IL-8 were detected in the sera of the patients with schizophrenia compared to controls. At the multivariate analysis, statistically significance held only for IL-2R concentration. Furthermore, positive correlation was found between symptom severity as measured by the PANSS and IL-6 levels as well as IL-2R levels. In Conclusion, our data indicate that elevated serum concentrations of IL-6, IL-8 and IL-2R are associated with severe clinical symptoms measured by the total, general, negative and positive scores of the PANSS scale.
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Affiliation(s)
- Shani Dahan
- Department of Medicine 'B' and Zabludowicz Center for Autoimmune Diseases, Sheba Medical Center, Tel-Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Israel
| | - Nicola Luigi Bragazzi
- Postgraduate School of Public Health, Department of Health Sciences (DISSAL), University of Genoa, Genoa, Italy
| | - Ayala Yogev
- Beer-Yaacov- Ness Ziona, Mental Health Center, Israel
| | - Mayan Bar-Gad
- Postgraduate School of Public Health, Department of Health Sciences (DISSAL), University of Genoa, Genoa, Italy
| | - Vivian Barak
- Immunology Laboratory for Tumor Diagnosis, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Howard Amital
- Department of Medicine 'B' and Zabludowicz Center for Autoimmune Diseases, Sheba Medical Center, Tel-Hashomer, Sackler Faculty of Medicine, Tel Aviv University, Israel.
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The Role of Infections and Autoimmune Diseases for Schizophrenia and Depression: Findings from Large-Scale Epidemiological Studies. CURRENT TOPICS IN NEUROTOXICITY 2015. [PMCID: PMC7122152 DOI: 10.1007/978-3-319-13602-8_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
An immunologic component to schizophrenia and depression has been increasingly recognized, which has led to extensive research into the associations with infections and autoimmune diseases. Large-scale nationwide epidemiological studies have displayed an increased prevalence of both autoimmune diseases and infections among persons with schizophrenia and depression. Autoimmune diseases, and especially the number of infections requiring hospitalization, increase the risk of schizophrenia and depression in a dose–response relationship. Infections are a common exposure and a broad spectrum of infections are associated with schizophrenia and depression. Particularly the autoimmune diseases with a potential presence of brain-reactive antibodies were associated with psychiatric disorders. However, the associations seem to be bidirectional, since the risk of autoimmune diseases and infections is also increased after diagnosis with schizophrenia and depression. The risk of autoimmune diseases was particularly increased in individuals with prior hospital contacts for infections. It has been suggested that inflammation and autoimmunity could be involved in the etiology and pathogenesis of some patients with symptoms of schizophrenia and depression. The psychiatric symptoms can be directly triggered by immune components, such as brain-reactive antibodies and cytokines, or infections reaching the central nervous system (CNS), or be secondary to systemic inflammation indirectly affecting the brain. However, the associations could also be caused by shared genetic factors, other environmental factors, or common etiological components. Nonetheless, autoimmune diseases and infections should be considered by clinicians in the treatment of individuals with psychiatric symptoms, since treatment would probably improve the psychiatric symptoms, quality of life, and the survival of the individuals.
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Liu W, Hao Q, Zhan S, Li D, Pan S, Li Y, Lin G, Pan G, Mahyoub R, Sun B. Long-Term Follow-Up of MRI-Guided Bilateral Anterior Capsulotomy in Patients with Refractory Schizophrenia. Stereotact Funct Neurosurg 2014; 92:145-52. [DOI: 10.1159/000360861] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 02/25/2014] [Indexed: 11/19/2022]
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Benros ME, Eaton WW, Mortensen PB. The epidemiologic evidence linking autoimmune diseases and psychosis. Biol Psychiatry 2014; 75:300-6. [PMID: 24199668 PMCID: PMC8797267 DOI: 10.1016/j.biopsych.2013.09.023] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 09/12/2013] [Accepted: 09/20/2013] [Indexed: 12/15/2022]
Abstract
This review summarizes the epidemiologic evidence linking autoimmune diseases and psychosis. The associations between autoimmune diseases and psychosis have been studied for more than a half century, but research has intensified within the last decades, since psychosis has been associated with genetic markers of the immune system and with excess autoreactivity and other immune alterations. A range of psychiatric disorders, including psychosis, have been observed to occur more frequently in some autoimmune diseases, such as systemic lupus erythematosus and multiple sclerosis. Many autoimmune diseases involve multiple organs and general dysfunction of the immune system, which could affect the brain and induce psychiatric symptoms. Most studies have been cross-sectional, observing an increased prevalence of a broad number of autoimmune diseases in people with psychotic disorders. Furthermore, there is some evidence of associations of psychosis with a family history of autoimmune disorders and vice versa. Additionally, several autoimmune diseases, individually and in aggregate, have been identified as raising the risk for psychotic disorders in longitudinal studies. The associations have been suspected to be caused by inflammation or brain-reactive antibodies associated with the autoimmune diseases. However, the associations could also be caused by shared genetic factors or common etiologic components such as infections. Infections can induce the development of autoimmune diseases and autoantibodies, possibly affecting the brain. Autoimmune diseases and brain-reactive antibodies should be considered by clinicians in the treatment of individuals with psychotic symptoms, and even if the association is not causal, treatment would probably still improve quality of life and survival.
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Affiliation(s)
- Michael E Benros
- National Centre for Register-Based Research, Aarhus University, Aarhus; Mental Health Centre Copenhagen, University of Copenhagen, Faculty of Health Sciences, Copenhagen; The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus, Denmark.
| | - William W Eaton
- Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Preben B Mortensen
- National Centre for Register-Based Research, Aarhus University, Aarhus; The Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH, Aarhus, Denmark
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Anti-brain autoantibodies in the serum of schizophrenic patients: a case-control study. Psychiatry Res 2013; 210:800-5. [PMID: 24103908 DOI: 10.1016/j.psychres.2013.09.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2013] [Revised: 06/04/2013] [Accepted: 09/08/2013] [Indexed: 11/23/2022]
Abstract
Schizophrenia is considered a neurodevelopmental disorder with a multifactorial pathogenesis where autoimmune factors may play a significant role. The aim of this study was to verify the presence of anti-brain autoantibodies in the serum of schizophrenic patients compared to healthy controls. Autoantibodies against brain were detected by the immunofluorescence method, utilizing sections of rat hippocampus and hypothalamus and of monkey cerebellum. Three different fluorescence patterns were observed, staining the nucleus-cytoplasm of neurons, the neuroendothelial of blood vessel and the neurofilaments. Search for other organ-specific and non organ-specific autoantibodies was performed in all sera by indirect immunofluorescence method, enzyme linked immunosorbent assay and chemiluminescence immunoassay. Results showed a significant association between schizophrenia and anti-brain autoantibodies against the neuroendothelium of blood vessel in hypothalamus, hippocampus and cerebellum; a significant nuclear and cytoplasmic staining of neurons was assessed only for the hippocampus. No other significant association was found, except between schizophrenia and anti-nuclear autoantibodies on HEp-2 cells. In conclusion, these results support the hypothesis of a significant association between schizophrenia and circulating anti-brain autoantibodies, suggesting a diffuse reactivity against the neuroendothelium of blood vessel and highlighting a nuclear and cytoplasmic staining of the neurons of hippocampus.
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Richard MD, Brahm NC. Schizophrenia and the immune system: pathophysiology, prevention, and treatment. Am J Health Syst Pharm 2012; 69:757-66. [PMID: 22517021 DOI: 10.2146/ajhp110271] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
PURPOSE Published evidence on established and theoretical connections between immune system dysfunction and schizophrenia is reviewed, with a discussion of developments in the search for immunologically-targeted treatments. SUMMARY A growing body of evidence indicates that immunologic influences may play an important role in the etiology and course of schizophrenia. A literature search identified more than 100 articles pertaining to suspected immunologic influences on schizophrenia published over the past 15 years. Schizophrenia researchers have explored a wide range of potential immune system-related causal or contributory factors, including neurobiological and neuroanatomical disorders, genetic abnormalities, and environmental influences such as maternal perinatal infection. Efforts to establish an immunologic basis for schizophrenia and identify reliable immune markers continue to be hindered by sampling challenges and methodological problems. In aggregate, the available evidence indicates that at least some cases of schizophrenia have an immunologic component, suggesting that immune-focused prevention strategies (e.g., counseling of pregnant women to avoid immune stressors) and close monitoring of at-risk children are appropriate. While antipsychotics remain the standard treatments for schizophrenia, a variety of drugs with immunologic effects have been investigated as adjunctive therapies, with variable and sometimes conflicting results; these include the cyclooxygenase-2 inhibitor celecoxib, immune-modulating agents (e.g., azathioprine and various anticytokine agents such as atlizumab, anakinra, and tumor necrosis factor-α blockers), and an investigational anti-interferon-γ agent. CONCLUSION The published evidence indicates that immune system dysfunction related to genetic, environmental, and neurobiological influences may play a role in the etiology of schizophrenia in a subset of patients.
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Arakelyan A, Zakharyan R, Khoyetsyan A, Poghosyan D, Aroutiounian R, Mrazek F, Petrek M, Boyajyan A. Functional characterization of the complement receptor type 1 and its circulating ligands in patients with schizophrenia. BMC Clin Pathol 2011; 11:10. [PMID: 21867543 PMCID: PMC3176470 DOI: 10.1186/1472-6890-11-10] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 08/25/2011] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Whereas the complement system alterations contribute to schizophrenia, complement receptors and regulators are little studied. We investigated complement receptor type 1 (CR1) expression on blood cells, the levels of circulating immune complexes (CIC) containing ligands of CR1, C1q complement protein and fragments of C3 complement protein (C1q-CIC, C3d-CIC), and CR1 C5507G functional polymorphism in schizophrenia patients and controls. RESULTS We found an increased C1q-CIC level and CR1 expression on blood cells, elevated number of CR1 positive erythrocytes and reduced number of CR1 positive lymphocytes and monocytes in patients compared to controls. No difference in the levels of C3d-CIC between groups was observed. Higher CR1 expression on erythrocytes in CC genotype versus CG+GG for both groups was detected, whereas no difference was observed for other cell populations. Our results indicated that schizophrenia is associated with the increased CR1 expression and C1q-CIC level. CONCLUSIONS Our study for the first time indicated that schizophrenia is associated with the increased CR1 expression and C1q-CIC level. Further studies in other ethnic groups are needed to replicate these findings.
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Affiliation(s)
- Arsen Arakelyan
- Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia, 7 Hasratyan St., 0014, Yerevan, Armenia
| | - Roksana Zakharyan
- Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia, 7 Hasratyan St., 0014, Yerevan, Armenia
- Faculty of Medicine and Dentistry, Palacky University, 6 I. P. Pavlova St., 775 20, Olomouc, Czech Republic
| | - Aren Khoyetsyan
- Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia, 7 Hasratyan St., 0014, Yerevan, Armenia
| | - David Poghosyan
- Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia, 7 Hasratyan St., 0014, Yerevan, Armenia
| | - Rouben Aroutiounian
- Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia, 7 Hasratyan St., 0014, Yerevan, Armenia
- Biological Faculty of Yerevan State University, 1 Al. Manoogian St., 0025, Yerevan, Armenia
| | - Frantisek Mrazek
- Faculty of Medicine and Dentistry, Palacky University, 6 I. P. Pavlova St., 775 20, Olomouc, Czech Republic
| | - Martin Petrek
- Faculty of Medicine and Dentistry, Palacky University, 6 I. P. Pavlova St., 775 20, Olomouc, Czech Republic
| | - Anna Boyajyan
- Institute of Molecular Biology, National Academy of Sciences of the Republic of Armenia, 7 Hasratyan St., 0014, Yerevan, Armenia
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Brain CB₂ Receptors: Implications for Neuropsychiatric Disorders. Pharmaceuticals (Basel) 2010; 3:2517-2553. [PMID: 27713365 PMCID: PMC4033937 DOI: 10.3390/ph3082517] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 08/04/2010] [Accepted: 08/09/2010] [Indexed: 12/26/2022] Open
Abstract
Although previously thought of as the peripheral cannabinoid receptor, it is now accepted that the CB2 receptor is expressed in the central nervous system on microglia, astrocytes and subpopulations of neurons. Expression of the CB2 receptor in the brain is significantly lower than that of the CB1 receptor. Conflicting findings have been reported on the neurological effects of pharmacological agents targeting the CB2 receptor under normal conditions. Under inflammatory conditions, CB2 receptor expression in the brain is enhanced and CB2 receptor agonists exhibit potent anti-inflammatory effects. These findings have prompted research into the CB2 receptor as a possible target for the treatment of neuroinflammatory and neurodegenerative disorders. Neuroinflammatory alterations are also associated with neuropsychiatric disorders and polymorphisms in the CB2 gene have been reported in depression, eating disorders and schizophrenia. This review will examine the evidence to date for a role of brain CB2 receptors in neuropsychiatric disorders.
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