Tumor necrosis factor-α and -β genetic polymorphisms as a risk factor in Saudi patients with schizophrenia

Mendelian randomization analysis of causal and druggable circulating inflammatory proteins in schizophrenia

Background

Schizophrenia (SZ) is a severe mental disorder with complex origins. Observational studies suggested that inflammatory factors may play a role in the pathophysiology of SZ and we aim to investigate the potential genetic connection between them by examining the causal impact of circulating inflammatory proteins on SZ.

Methods

We utilized Mendelian randomization (MR) analysis to assess the causal relationship between circulating inflammatory proteins and SZ and the GWAS summary datasets were sourced from public databases. The SZ dataset comprised 74,776 cases and 101,023 controls, while the summary results for 91 plasma proteins in 14,824 participants were obtained through the Olink Target platform. Moreover, to identify and evaluate potential drug targets, we searched the Drug-Gene Interaction Database (DGIdb).

Results

The results of the MR study confirmed that nine inflammatory proteins had a causal effect on SZ. Among these proteins, IL1A (OR: 0.93), TNFB (OR: 0.94), TNFSF14 (OR: 0.96), and CD40 (OR: 0.95) exhibited protective effects against SZ. Conversely, CCL23 (OR: 1.04), CCL19 (OR: 1.04), 4EBP1 (OR: 1.06), TWEAK (OR: 1.08), and DNER (OR: 1.10) were associated with an increased risk of SZ. The MR-Egger and weighted median methods also supported the direction of these effects. According to the Gene-Drug analysis, LTA, IL1A, CD40, and 4EBP1 can serve as drug targets.

Conclusions

Our study established causal relationships between circulating inflammatory proteins and SZ. It may be beneficial to personalize the treatment of SZ by incorporating inflammation management into the treatment regimen.

Microglia and cognitive impairment in schizophrenia: translating scientific progress into novel therapeutic interventions

Cognitive impairment is a core clinical feature of schizophrenia, exerting profound adverse effects on social functioning and quality of life in a large proportion of patients with schizophrenia. However, the mechanisms underlying the pathogenesis of schizophrenia-related cognitive impairment are not well understood. Microglia, the primary resident macrophages in the brain, have been shown to play important roles in psychiatric disorders, including schizophrenia. Increasing evidence has revealed excessive microglial activation in cognitive deficits related to a broad range of diseases and medical conditions. Relative to that about age-related cognitive deficits, current knowledge about the roles of microglia in cognitive impairment in neuropsychiatric disorders, such as schizophrenia, is limited, and such research is in its infancy. Thus, we conducted this review of the scientific literature with a focus on the role of microglia in schizophrenia-associated cognitive impairment, aiming to gain insight into the roles of microglial activation in the onset and progression of such impairment and to consider how scientific advances could be translated to preventive and therapeutic interventions. Research has demonstrated that microglia, especially those in the gray matter of the brain, are activated in schizophrenia. Upon activation, microglia release key proinflammatory cytokines and free radicals, which are well-recognized neurotoxic factors contributing to cognitive decline. Thus, we propose that the inhibition of microglial activation holds potential for the prevention and treatment of cognitive deficits in patients with schizophrenia. This review identifies potential targets for the development of new treatment strategies and eventually the improvement of care for these patients. It might also help psychologists and clinical investigators in planning future research.

Role of TNF-α -308G/A Polymorphism in Bipolar Disorder and its Relationship with Clinical and Demographic Variables

Objective

Gene-environment interactions might play a significant role in the development of bipolar disorder (BD). The objective of the current study was to investigate the association between tumor necrosis factor (TNF)-α -308 G/A polymorphism and BD and conduct a bioinformatics analysis of the protein-protein network of TNF-α. Gene-environment interactions and the relationship between stressful life events (SLEs) and substance abuse with TNF genotypes and other characteristics were analyzed.

Methods

The genomic deoxyribonucleic acid (DNA) of 400 patients with BD and 200 control subjects were extracted and genotyped for TNF-α -308 G/A polymorphism. SLEs and substance abuse were evaluated using the Life Event and Difficulty Schedule (LEDS) and a self-designed substance abuse questionnaire for the events six months prior to the onset of the disease, respectively. Gene-environment interactions were assessed by multiple statistical tools. Bioinformatics analysis of the TNF-α network and its interacting proteins was carried out using STRING and Cytoscape softwares.

Results

Genotyping analysis revealed a significant association between TNF-α -308 G/A polymorphism and BD (p<0.009). Furthermore, analysis of gene-environment interaction revealed a significant association between TNF-α -308 G/A and SLEs (p=0.001) and TNF-α -308 G/A and substance abuse (p=0.001). Three distinct proteins, RELA, RIPK1, and BIRC3, were identified through hub analysis of the protein network.

Conclusion

TNF-α -308 G/A polymorphism is positively associated with BD. SLEs and substance abuse might trigger the early onset of BD. Proteins identified through bioinformatics analysis might contribute to the TNF-α mediated pathophysiology of BD and can be the potential therapeutic targets.

Association between Tumor Necrosis factor-Alpha(TNF-a) polymorphisms and Schizophrenia: an updated meta-analysis

BACKGROUND

Previous studies have explored associations between Tumour Necrosis factor-Alpha (TNF-a) polymorphisms and Schizophrenia. Their results were controversial. We conducted a meta-analysis to clarify the association between TNF-a - 308 G/A(rs1800629), -1031T/C(rs1799964), -863C/A(rs1800630) and -857 C/T (rs1799724) polymorphisms and Schizophrenia.

METHODS

All the studies that investigated the association between TNF-a polymorphisms and Schizophrenia published before 15 October 2020 were included in. The literature were comprehensively searched and identified in 2 English databases and 2 Chinese databases. The odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

For -1031 T/C polymorphism, at the overall analysis, significantly decreased Schizophrenia risk was found in T allele in the allele model (p = 0.006, OR = 0.88) and increased Schizophrenia risk was found in TC + CC genotype in the dominant model (p = 0.005, OR = 1.17). Similarly, the same results were obtained when pooled analyses were included in high-quality studies (allele model: p = 0.005, OR = 0.86; dominant model: p = 0.007, OR = 1.20). In addition, when stratified by ethnicity, the results showed that in allele model, the T allele decreased Schizophrenia risk in East Asian (p = 0.031, OR = 0.90).

CONCLUSION

The association may most likely result from less-credible, rather than from true associations or biological factors on the TNF-a - 1031 T/C polymorphism with Schizophrenia risk.KeypointsFor -1031T/C polymorphism, at the overall analysis, significantly decreased schizophrenia risk was found in T allele in the allele model, and increased schizophrenia risk was found in TC + CC genotype in the dominant model.In allele model, the T allele decreased schizophrenia risk in East Asian when stratified by ethnicity, and in the dominant model, TC + CC genotype increased schizophrenia risk in East Asian.

Linking Inflammation, Aberrant Glutamate-Dopamine Interaction, and Post-synaptic Changes: Translational Relevance for Schizophrenia and Antipsychotic Treatment: a Systematic Review

Evidence from clinical, preclinical, and post-mortem studies supports the inflammatory/immune hypothesis of schizophrenia pathogenesis. Less evident is the link between the inflammatory background and two well-recognized functional and structural findings of schizophrenia pathophysiology: the dopamine-glutamate aberrant interaction and the alteration of dendritic spines architecture, both believed to be the “quantal” elements of cortical-subcortical dysfunctional network. In this systematic review, we tried to capture the major findings linking inflammation, aberrant glutamate-dopamine interaction, and post-synaptic changes under a direct and inverse translational perspective, a paramount picture that at present is lacking. The inflammatory effects on dopaminergic function appear to be bidirectional: the inflammation influences dopamine release, and dopamine acts as a regulator of discrete inflammatory processes involved in schizophrenia such as dysregulated interleukin and kynurenine pathways. Furthermore, the link between inflammation and glutamate is strongly supported by clinical studies aimed at exploring overactive microglia in schizophrenia patients and maternal immune activation models, indicating impaired glutamate regulation and reduced N-methyl-D-aspartate receptor (NMDAR) function. In addition, an inflammatory/immune-induced alteration of post-synaptic density scaffold proteins, crucial for downstream NMDAR signaling and synaptic efficacy, has been demonstrated. According to these findings, a significant increase in plasma inflammatory markers has been found in schizophrenia patients compared to healthy controls, associated with reduced cortical integrity and functional connectivity, relevant to the cognitive deficit of schizophrenia. Finally, the link between altered inflammatory/immune responses raises relevant questions regarding potential new therapeutic strategies specifically for those forms of schizophrenia that are resistant to canonical antipsychotics or unresponsive to clozapine.

Glial changes in schizophrenia: Genetic and epigenetic approach

BACKGROUND

Schizophrenia (SCZ) is a severe mental illness that affects one percent of the population, affecting how people think, feel, and behave. Evidence suggests glial cell alteration and some researchers have found genetic risk loci and epigenetic marks that may regulate glia-related genes implicated in SCZ.

AIM

The aim of this study is to identify genetic and epigenetic changes that have been reported in glial cells or glial-associated genes in SCZ.

MATERIALS AND METHODS

We searched the articles from PubMed, PubMed Central, Medline, Medscape, and Embase databases up to December 2020 to identify relevant peer-reviewed articles in English. The titles and abstracts were screened to eliminate irrelevant citations.

RESULTS

Twenty-four original articles were included in the review. Studies were categorized into the following four thematic via: (1) oligodendrocytes, (2) microglia, (3) astrocytes, and (4) perspectives.

CONCLUSION

This study is the first of its kind to review research on genetic variants and epigenetic modifications associated with glia-related genes implicated in SCZ. Epigenetic evidence is considerably less than genetic evidence in this field. Understanding the pathways of some risk genes and their genetic and epigenetic regulation allows us to understand and find potential targets for future interventions in this mental illness.

Association between TNF-alpha polymorphism and the age of first suicide attempt in chronic patients with schizophrenia

Patients with schizophrenia (SCZ) exhibit higher suicide rates than the general population. However, the molecular mechanism remains poorly understood. Tumor necrosis factor (TNF)-alpha polymorphisms have been repeatedly indicated to play a pathogenetic role in various mental disorders, but none of these studies focused on the susceptibility to suicidal behavior in SCZ. We recruited 1087 chronic inpatients with SCZ and 576 controls to assess the psychopathological symptoms of SCZ using the Positive and Negative Syndrome Scale scales. We selected 2 polymorphisms (-308G>A and -1031C>T) in the TNF-alpha gene and analyzed their associations with SCZ and suicide. Our results showed that TNF-alpha -308G>A and -1031C>T were not related to SCZ and suicide. However, we found that suicide attempters with the C allele carriers exhibited suicidal behaviors significantly later than those with TT genotype in the SCZ patients. The haplotype containing the T allele of the -1031 was significantly associated with the age of suicide initiation. Further logistic regression analysis showed that -1031C>T interacted with psychopathological symptoms and drinking, age of smoking, and related to the initiation age of suicide attempts. Our study demonstrated that the TNF-alpha variants may affect the age at which suicide attempts started among SCZ suicide attempters.

Haplotypes of TNFα/β Genes Associated with Sex-Specific Paranoid Schizophrenic Risk in Tunisian Population

Several medical research findings have announced a strong association between the biology of cytokines and various brain activities. Since growing evidences suggest the crucial and complex role of the tumor necrosis factor in the CNS, we have hypothesized that functional genetic variants of the LTA and TNFA genes (LTA +252A/G (rs909253) and TNFA -857C/T (rs1799724) and TNFA -238G/A (rs361525)) may be involved in the predisposition to schizophrenia. This research is based on a case-control study. The RFLP-PCR genotyping was conducted on a Tunisian population composed of 208 patients and 208 controls. We found a strong significant overrepresentation of the minor alleles (G, T, and A, respectively) in all patients compared with controls (p = 0.003, OR = 1.55; p = 0.005, OR = 1.78; and p = 0.0001, OR = 1.74, respectively). This correlation was confirmed for male but not for female patients. Interestingly, the frequencies of the minor alleles were significantly more common among patients with paranoid schizophrenia when compared with controls (p = 0.003, OR = 1.75; p = 5 · 10^-6, OR = 3.04; and p = 4 · 10^-6, OR = 2.35, respectively). This potential association was confirmed by a logistic binary regression analysis only for the development of the paranoid form of schizophrenia (p = 0.001/OR = 2.6; p = 0.0002/OR = 3.2; and p = 0.0004/OR = 3.1, respectively) and remained not significant for the other subtypes. Moreover, our study showed an important association between GCA haplotype and the development of this pathological form (p = 10^-4, OR = 3.71). In conclusion, our results proved a significant association between the three polymorphisms and paranoid schizophrenia, at least in the Tunisian population, suggesting a substantially increased risk for paranoid schizophrenia with dominant inheritance of these three minor alleles.

Inflammatory Markers in Anorexia Nervosa: An Exploratory Study

Inflammation has been suggested to play a pathophysiological role in anorexia nervosa (AN). In this exploratory cross-sectional study, we measured serum concentrations of 40 inflammatory markers (including cytokines, chemokines, and adhesion molecules) and brain-derived neurotrophic factor (BDNF) in people with AN (n = 27) and healthy controls (HCs) (n = 13). Many of these inflammatory markers had not been previously quantified in people with AN. Eating disorder (ED) and general psychopathology symptoms were assessed. Body mass index (BMI) and body composition data were obtained. Interleukin (IL)-6, IL-15, and vascular cell adhesion molecule (VCAM)-1 concentrations were significantly elevated and concentrations of BDNF, tumor necrosis factor (TNF)-β, and vascular endothelial growth factor (VEGF)-A were significantly lower in AN participants compared to HCs. Age, BMI, and percentage body fat mass were identified as potential confounding variables for several of these inflammatory markers. Of particular interest is that most of the quantified markers were unchanged in people with AN, despite them being severely underweight with evident body fat loss, and having clinically significant ED symptoms and severe depression and anxiety symptoms. Future research should examine the replicability of our findings and consider the effect of additional potential confounding variables, such as smoking and physical activity, on the relationship between AN and inflammation.

Tumor necrosis factor-alpha -1031T/C polymorphism is associated with cognitive deficits in chronic schizophrenia patients versus healthy controls

Recent compelling research has demonstrated a pathophysiologic role for proinflammatory cytokines of microglial origin in decreasing neurocognitive function. Psychiatric diseases are already known to have reduced cognitive function and are also associated with increased inflammation. To elaborate on these data, our study aims to investigate how a particular polymorphism of the tumor necrosis factor gene, TNF-α -1031T/C, affects neurocognitive performance in patients with schizophrenia. We recruited 905 patients with schizophrenia and 571 healthy control subjects. We employed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to test for neurocognitive function and the positive and negative syndrome scale to evaluate schizophrenia severity. The -1031T/C polymorphism was genotyped in both healthy controls and schizophrenic patients. Our results demonstrate that patients with the C allele (either T/C or C/C) possessed increased immediate memory index, visuospatial/constructional index, and RBANS total scores as compared to patients without it (p < .05). In healthy controls, there was no significant difference across genotypes (p > .05). Our findings demonstrate that the TNF-α -1031T/C polymorphism may not play a role in the susceptibility of schizophrenia itself, but may be involved in the cognitive deficits of schizophrenia. This suggests an important role for cytokine signaling in mediating the severity of cognitive dysfunction in schizophrenia.

Associations of TNF-α -238 A/G and IL-10 -1082 G/A Genetic Polymorphisms With the Risk of NONFH in the Chinese Population

The study aims to explore the roles of common polymorphisms of Tumor Necrosis Factor-α (TNF-α) (-238 A/G and -308 A/G) and IL-10 (-819 T/C and -1082 G/A) genes in the risk of non-traumatic osteonecrosis of the femoral head (NONFH). One hundred and forty-seven NONFH patients and 135 healthy individuals were selected as the case and control groups. qRT-PCR and Western blotting techniques detected mRNA as well as protein expressions of TNF-α and IL-10 of each genotype in both the case and control groups. The GA genotype and the A allele of TNF-α -238 A/G were higher in the case group than in the control group. Compared with the control group, AA, GA, and AG + AA genotypes as well as the A allele of IL-10-1082 G/A were all lower in the case group. In the case groups increased levels of TNF-α as well as decreased levels of IL-10 expression when compared with the control group. TNF-α expression of TNF-α-238 GA genotype was significantly higher than that in patients with GG genotype, while the IL-10 expression of GA and AA genotypes of IL-10-1082 was significantly lower than in that of patients with the GG genotype. TNF-α protein expression in the GA genotype was significantly higher than in the GG genotype. In relation to TNF-α -238, TNF-α protein expression of GA and AA genotypes had significantly reduced more so than the GG genotype in IL-10-1082. TNF-α-238 A/G and IL-10-1082 G/A may be involved as risk factors of NONFH. J. Cell. Biochem. 118: 4872-4880, 2017. © 2017 Wiley Periodicals, Inc.