Insights into myelin dysfunction in schizophrenia and bipolar disorder

Background: Hypothalamic-pituitary-adrenal axis gene variants and childhood trauma (CT) are considered risk factors for suicide attempt (SA). The aim of the present study was analyzed gene x environment (GxE) interaction of NR3C1, NR3C2, and CT, and NR3C1 and NR3C2 gene expression in the development of SA with CT. Participants and Methods: A total of 516 psychiatric Mexican patients from Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz. Among them, 274 had SA at least once and 242 had not SA. Genetic variants of NR3C1 and NR3C2 were genotyped in all the patients, of which were obtained the CT information from medical records. Additionally, the gene expression of NR3C1 and NR3C2 was also analyzed for a subsample of 96 patients, obtaining the TC information from Childhood Trauma Questionnaire (CTQ). Results: The analysis showed a GxE interaction of NR3C1, NR3C2, and CT (OR=2.8, 95% CI [1.9– 3.9], p< 0.0001). Interactions were also observed with neglect (OR=2.1, 95% CI [1.4– 3.1], p< 0.0001), emotional abuse (OR=2.1, 95% CI [1.5– 3], p< 0.0001), and sexual abuse (OR=2.4, 95% CI [1.4– 2.9], p< 0.0001) in the prediction of SA. The analysis of gene expression identified an overexpression of NR3C1 in SA patients with high scores for physical and sexual abuse (p< 0.0001; p< 0.0006, respectively) and emotional neglect (p=0.014). An underexpression was observed of NR3C2, associated with high scores of trauma subtypes (p< 0.0001) except physical neglect. Additionally, we observed an overexpression of NR3C1 gene in patients with SA carriers of A allele of rs6191 (p=0.0015). Also, overexpression of NR3C1 gene in carriers of G allele of rs6198 and underexpression of NR3C2 gene in carriers of G allele of rs5522 (p< 0.0001). Conclusion: Our findings suggest that genetic variants of NR3C1 and NR3C2 differentially affect expression levels, increasing the susceptibility to SA in psychiatric patients with a history of CT.

Introduction: Schizophrenia is a complex psychiatric disorder with an important genetic contribution. Immunological abnormalities have been reported in schizophrenia. Toll-like receptor (TLR) genes play an important role in the activation of the innate immune response, which may help to explain the presence of inflammation in people with this disorder. The aim of this study was to analyze the association of TLR1, TLR2, and TLR6 gene polymorphisms in the etiology of schizophrenia. Methods: We included 582 patients with schizophrenia and 525 healthy controls. Genetic analysis was performed using allelic discrimination with TaqMan probes. Results: We observed significant differences between patients and controls in the genotype and allele frequencies of TLR1/rs4833093 (χ 2 = 17.3, p = 0.0002; χ 2 = 15.9, p = 0.0001, respectively) and TLR2/rs5743709 (χ 2 = 29.5, p = 0.00001; χ 2 = 7.785, p = 0.0053, respectively), and in the allele frequencies of TLR6/rs3775073 (χ 2 = 31.1, p = 0.00001). Finally, we found an interaction between the TLR1/rs4833093 and TLR2/rs5743709 genes, which increased the risk of developing schizophrenia (OR = 2.29, 95% CI [1.75, 3.01]). Discussion: Our findings add to the evidence suggesting that the activation of innate immune response might play an important role in the development of schizophrenia.

Schizophrenia (SZ) is a chronic disabling mental disorder with high heritability, and several immune-regulating genes have been implicated in its pathophysiology In this study, we investigated the expression of Toll-like receptors (TLRs) 1, 2, and 6 in peripheral blood monocytes from SZ patients and healthy control subjects (HCSs) in the Mexican population, focusing on specific SZ-associated gene variants. Gene expressions were assessed by qPCR, and protein expression was measured using flow cytometry. The secretory profiles of MALP2-stimulated monocytes were evaluated through immunoproteomic arrays. Our results indicate that patients with SZ carrying the rs4833093/TLR1 GG genotype exhibited significantly lower TLR1 gene expression compared to TT carriers. Notably, HCSs with the TT genotype showed markedly higher TLR1 protein expression, while all patients with SZ exhibited significantly reduced protein levels regardless of genotype. Furthermore, monocytes from patients with SZ displayed altered secretion profiles upon TLR stimulation, with significant elevations in IL-18, uPAR, angiopoietin-2, and serpin E1, alongside reductions in MCP-1, IL-17A, IL-24, MIF, and myeloperoxidase compared to HCSs. These findings suggest a dysfunctional TLR-mediated innate immune response in SZ.