Interaction of tumor necrosis alpha - G308A and epidermal growth factor gene polymorphisms in early-onset schizophrenia

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.

Association between TNF-α gene polymorphisms and susceptibility of myelodysplastic syndromes: a meta-analysis

OBJECTIVE

Myelodysplastic syndromes (MDS) constitute a heterogeneous group of clonal hematological diseases. Previous investigations reported that tumor necrosis factor-alpha (TNF-α) gene polymorphisms were associated with MDS susceptibility, but the results remained controversial. Thus, we conducted a meta-analysis to higher elucidate the correlation between TNF-α gene polymorphisms and MDS susceptibility.

METHODS

The PubMed, Cochrane Library, Embase, Chinese National Knowledge Infrastructure (CNKI), and Wan Fang databases were searched for eligible literatures published up to July 2021. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were applied to evaluate the strength of association.

RESULTS

Eight studies involving 1180 MDS patients and 1387 controls were included in this meta-analysis. For the TNF-α G308A polymorphism, we confirmed that the G allele (G versus A: P = 0.001), GG genotypes (GG versus GA: P = 0.005; GG versus GA + AA: P = 0.002), and GG + AA genotypes (GG + AA versus GA: P = 0.008) was significantly associated with decreased MDS susceptibility according to different genetic models. Furthermore, the G308A polymorphism was significantly correlated with decreased occurrence risk of MDS in the Caucasian population as compared with Asians in the above four genetic models (P < 0.05). However, no significant association was observed between the TNF-α G238A polymorphism and MDS risk.

CONCLUSION

This research showed that TNF-α G308A polymorphism might be a potential biomarker in early clinical screening of MDS, which would contribute to improving the individualized prevention of MDS patients in clinic.

The associations of TNF-α gene polymorphisms with bone mineral density and risk of osteoporosis: A meta-analysis

OBJECTIVE

Fracture is a common consequence of osteoporosis and is associated with high morbidity and mortality. Recently, increasing evidence has suggested that polymorphisms in tumor necrosis factor-α (TNF-α) gene were associated with osteoporosis risk and bone mineral density (BMD), but results remain conflicting. We herein performed a meta-analysis based on evidence currently available from the literature to make a more precise estimation of these relationships.

METHODS

The PubMed, EMBASE, Cochrane Library, CNKI (China National Knowledge Infrastructure) and Wan Fang databases were searched for eligible studies. Articles meeting the inclusion criteria were comprehensively reviewed and all available data were accumulated. The pooled odds ratios (ORs) or mean differences (MDs) and corresponding 95% confidence intervals (CIs) were applied to assess the strength of the relationships.

RESULTS

A total of 15 studies involving 5273 subjects were included in our meta-analysis. The GG genotype of TNF-α G308A was associated with an increased risk of osteoporosis under a mutant model (GG vs GA+AA: OR = 0.63, 95% CI: 0.51-0.77, P < 0.0001, I²  = 31%). Additionally, we also observed a significant association between G308A polymorphism and BMD of lumbar spine (AA vs GG: P = 0.01, I²  = 53%). However, TNF-α T1031C, C857T and C863A polymorphisms had no obvious impacts on osteoporosis risk.

CONCLUSIONS

The present meta-analysis demonstrated that TNF-α G308A polymorphism may act as a potential candidate biomarker for screening, diagnosis, and treatment of osteoporosis, which will help improve individualized therapy of osteoporosis patients in clinics.

Molecular mechanisms involved in epidermal growth factor receptor-mediated inhibition of dopamine D3 receptor signaling

The phenomenon wherein the signaling by a given receptor is regulated by a different class of receptors is termed transactivation or crosstalk. Crosstalk between receptor tyrosine kinases (RTKs) and G protein-coupled receptors (GPCRs) is highly diverse and has unique functional implications because of the distinct structural features of the receptors and the signaling pathways involved. The present study used the epidermal growth factor receptor (EGFR) and dopamine D₃ receptor (D₃R), which are both associated with schizophrenia, as the model system to study crosstalk between RTKs and GPCRs. Loss-of-function approaches were used to identify the cellular components involved in the tyrosine phosphorylation of G protein-coupled receptor kinase 2 (GRK2), which is responsible for EGFR-induced regulation of the functions of D₃R. SRC proto-oncogene (Src, non-receptor tyrosine kinase), heterotrimeric G protein Gβγ subunit, and endocytosis of EGFR were involved in the tyrosine phosphorylation of GRK2. In response to EGF treatment, Src interacted with EGFR in a Gβγ-dependent manner, resulting in the endocytosis of EGFR. Internalized EGFR in the cytosol mediated Src/Gβγ-dependent tyrosine phosphorylation of GRK2. The binding of tyrosine-phosphorylated GRK2 to the T142 residue of D₃R resulted in uncoupling from G proteins, endocytosis, and lysosomal downregulation. This study identified the molecular mechanisms involved in the EGFR-mediated regulation of the functions of D₃R, which can be extended to the crosstalk between other RTKs and GPCRs.

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

BACKGROUND

Schizophrenia is one of the most common devastating psychiatric disorders that negatively affects the quality of life and psychosocial functions. Its etiology involves the interplay of complex polygenic influences and environmental risk factors. Inflammatory markers are well-known etiological factors for psychiatric disorders, including schizophrenia.

OBJECTIVE

The aim of this study was to investigate the association of proinflammatory cytokine genes, tumor necrosis factor (TNF)-α (-308G/A) and TNF-β (+252A/G) polymorphisms with schizophrenia susceptibility.

SUBJECTS AND METHODS

TNF-α and TNF-β genes were amplified using amplification refractory mutation system primers in 180 schizophrenia patients and 200 healthy matched controls recruited from the Psychiatry Clinic of Prince Sultan Military Medical City, Riyadh. The frequencies of alleles and genotypes of TNF-α (-308G/A) and TNF-β (+252A/G) polymorphisms in patients were compared with those in controls.

RESULTS

The frequencies of TNF-α (-308) allele A and genotype GA were significantly higher, while those of allele G and genotype GG were lower in schizophrenia patients as compared to controls, indicating that genotype GA and allele A of TNF-α (-308G/A) may increase susceptibility to schizophrenia, while genotype GG and allele G may reduce it. On the other hand, the distribution of alleles and genotypes of TNF-β (+252A/G) polymorphism does not differ significantly in patients from controls; however, the frequency of genotype GG of TNF-β (+252A/G) was significantly higher in male patients than in female patients. The distribution of TNF-α (-308G/A) and TNF-β (+252A/G) polymorphisms was almost similar in schizophrenia patients with negative or positive symptoms.

CONCLUSION

TNF-α (-308G/A) and TNF-β (+252G/A) polymorphisms may increase the susceptibility to schizophrenia in Saudi patients and could be a potential risk factor for its etiopathogenesis. However, further studies are warranted involving a larger sample size to strengthen our findings.

Inflammatory cytokine network in schizophrenia

OBJECTIVES

The purpose of this review is to analyse, sum up and discuss the available literature on the role of inflammation and inflammatory cytokines in the pathogenesis of schizophrenia.

METHODS

An electronic literature search of peer-reviewed English language articles using Pubmed was undertaken. These articles together with those published by us provided the background for the present review.

RESULTS

An overview of the available literature on this issue clearly demonstrated the alterations in mRNA and protein expression levels of several proinflammatory and chemotactic cytokines in patients with schizophrenia. Importantly, some of these changes are genetically determined. It was noteworthy that, depending on the study population, some variations of the data obtained are detected.

CONCLUSIONS

Altered inflammatory cytokine production, both genetically and environmentally determined, is implicated in schizophrenia and contributes to disease-associated low-grade systemic inflammation. Proinflammatory and chemotactic cytokines and their receptors may represent additional therapeutic targets for treatment of schizophrenia.

Lack of association between TNFα rs1800629 polymorphism and schizophrenia risk: a meta-analysis

Evidence has suggested that tumour necrosis factor α (TNFα) may be involved in the aetiology of schizophrenia, but the underlying association between TNFα-308G/A polymorphism (rs1800629) and schizophrenia risk is still ambiguous. This meta-analysis was performed to quantitatively summarise the evidence for such a relationship. Eligible studies were identified by searching PubMed, EMBASE, CNKI (China National Knowledge Infrastructure), CBM (Chinese Biomedical Literature Database) and WANFANG databases within a range of published years from 1990 to July 2012. The odds ratio (OR) corresponding to the 95% confidence interval (CI) was used to assess the different associations. Twenty-one studies with 4340 cases and 5745 controls were included in this meta-analysis. The pooled examination displayed that there was no significant association between TNFα-308G/A polymorphism and susceptibility to schizophrenia overall (OR=1.047, 95% CI=0.876-1.253, P=0.614 for A vs. G), and no difference in Caucasian subgroup (OR=1.041, 95% CI=0.815-1.331, P=0.747) and Asian subgroup (OR=1.057, 95% CI=0.807-1.386, P=0.686). Lack of association was also found in males (OR=0.862, 95% CI=0.413-1.797, P=0.692) and females (OR=0.797, 95% CI=0.579-1.097, P=0.163) with a dominant model. Taken together, this meta-analysis suggests that TNFα-308G/A polymorphism may not be associated with schizophrenia susceptibility.

Prenatal inflammation and neurodevelopment in schizophrenia: a review of human studies

A confluence of evidence supports an association between prenatal inflammation and risk of schizophrenia. Outside of studies of prenatal infections and risk of schizophrenia, other relevant human studies of prenatal inflammation and neurodevelopment in schizophrenia have not been reviewed. In this paper, we review human studies of 1) prenatal inflammation and risk of schizophrenia, 2) inflammation as a potential common mediator of several prenatal risk factors for schizophrenia other than prenatal infections, 3) prenatal inflammation and immune function, neurocognition, brain morphology, and gene expression in adult offspring with schizophrenia, and 4) gene by environment and gene by gene interactions relevant to these associations. We suggest future areas for human studies research based on existing findings.

BDNF gene is a genetic risk factor for schizophrenia and is related to the chlorpromazine-induced extrapyramidal syndrome in the Chinese population

BACKGROUND

Brain-derived neurotrophic factor (BDNF) belongs to a family of the neurotrophin, which plays important roles in the neurodevelopment of dopaminergic-related systems and interacts with meso-limbic dopaminergic systems involved in the therapeutic response to antipsychotics. Functional experiments have suggested that BDNF may be involved in the etiology of schizophrenia.

METHODS AND RESULTS

In this study, we genotyped two important functional polymorphisms in the BDNF gene using a sample of Han Chinese patients consisting of 340 schizophrenic patients and 343 healthy controls. We found a statistical difference in the 232-bp allele distribution of the BDNF gene (GT)n dinucleotide repeat polymorphism between the schizophrenic patients and controls. In early onset patients, the 234-bp allele had a risk role. For the chlorpromazine-induced extrapyramidal syndrome, the 230-bp allele and the 234-bp allele acted in opposite directions, that is, patients with the 230-bp allele of the (GT)n polymorphism exhibited a lower degree of induced extrapyramidal syndrome. Haplotype-based analysis also revealed a very important risk haplotype (P=0.0000226546).

CONCLUSION

These findings suggest that BDNF plays an important role in the susceptibility to schizophrenia and that the (GT)n repeat polymorphism of the BDNF gene may be an independent contributor to the chlorpromazine treatment-sensitive form of schizophrenia.

No association between the tumor necrosis factor-alpha gene promoter polymorphisms and schizophrenia in a Japanese population

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotrophic cytokine and exerts neuroprotective and neurodegenerative effects in brain. Several studies have indicated that TNF-alpha is likely related to the pathogenesis of schizophrenia. Recent genetic investigations have revealed that a TNF-alpha gene promoter polymorphism (-G308A) is associated with schizophrenia, although negative findings have also been reported. To assess whether the TNF-alpha gene promoter variants including -G308A could be implicated in vulnerability to schizophrenia, we conducted a case-control association analysis (265 cases and 424 controls) and the transmission disequilibrium test (TDT) analysis (83 trios) for four polymorphisms (-G238A, -G308A, -C857T and -T1031C) in Japanese subjects. In a case-control analysis, there was no significant association between the promoter polymorphisms or haplotypes in the TNF-alpha gene and schizophrenia. In the TDT analysis, we also did not observe transmission distortion. Our results suggest that the above four polymorphisms in the promoter region of the TNF-alpha gene appear not to confer increased susceptibility for schizophrenia in a Japanese population.

-G308A tumor necrosis factor alpha functional polymorphism and schizophrenia risk: meta-analysis plus association study

Research on -G308A functional polymorphism in the tumor necrosis factor alpha (TNFalpha) gene as a susceptibility factor for schizophrenia has provided contrasting results in different populations. Therefore we conducted a meta-analysis of the published case-control association studies and a replication study in a large sample. Meta-analyses (total sample: 2512 cases versus 3223 controls) showed that the AA genotype was weakly associated with schizophrenia susceptibility in Caucasoids (Odd Ratio OR=1.65, 95% CI=1.00-2.71 Z=1.98 p=0.05). The replication case-control association study (323 DSM-IV-TR schizophrenia patients and 346 controls) showed that the A allele conferred an increased susceptibility for schizophrenia only in males (OR=1.73, 95% CI=1.07-2.79, p=0.025), and the association became more specific when only patients of the paranoid subtype were compared to the controls (relative risk ratio=3.09, 95% CI=1.28-7.47, p=0.012). The presence of the A allele was also associated with a later age at onset of schizophrenia in the whole sample (F(1,291)=7.094, p=0.008). Our results confirm that TNFalpha A allele could have an effect on vulnerability to schizophrenia but further studies revaluating the role of gender and diagnostic subtypes are necessary to confirm these findings.

Schizophrenia susceptibility genes converge on interlinked pathways related to glutamatergic transmission and long-term potentiation, oxidative stress and oligodendrocyte viability

Over 130 genes have been associated with schizophrenia in genetic studies. None of these has reached a sufficient level of confidence to be accepted as a universal susceptibility gene and problems of replicability suggest that many may be false positives. Nevertheless, these genes can be grouped into distinct families related to glutamate transmission (in particular related to NMDA receptor function), the control of synaptic plasticity, dopaminergic transmission, oxidative stress, glutathione and quinone metabolism and oligodendrocyte viability. These families mirror the processes disrupted in the schizophrenic brain and certain gene families can be linked together to form a clearly defined signalling cascade involved in the phenomenon of NMDA receptor-dependent long-term potentiation and synaptic plasticity, that may be interconnected with oligodendrocyte and oxidative stress-related pathways. Many of the protein products of these genes interact with each other, forming complex integrated networks. Certain high-interest genes (for example DISC1, NRG1, COMT) may exert multiple effects on different areas of these pathways, while others exert more specific effects on certain branches. The convergence of a large number of genes on a definable signaling network raises the possibility of numerous interactions between gene candidates, and suggests that a targeted multigenic pathway approach would be useful in gene association studies.

One year outcome in first episode schizophrenia. Predictors of relapse

The aim of this study was to identify the predictors of outcome at one year follow-up after the first psychotic episode of schizophrenia. Seventy-nine first-episode schizophrenia patients were assessed monthly with the Brief Psychiatric Rating Scale (BPRS), Scale for Assessment of Positive Symptoms (SAPS), and Scale for Assessment of Negative Symptoms (SANS) after discharge from their first hospitalization. Outcome measures were presence of relapse and rehospitalization, level of global functioning, employment status and severity of symptoms at one year. A total of 33% of the patients had a relapse, and 12.1% were rehospitalized during one year follow-up. Premorbid childhood functionality was worse in patients who had relapse, but there was no correlation between premorbid adjustment scores and BPRS, SANS and SAPS scores at one year. There was no difference in duration of untreated psychosis (DUP) between patients who had relapse and not; however, the patients who had double relapse, had longer DUP than those without relapse. The time period between discharge and rehospitalization was shorter in patients with longer DUP. Functionality in childhood and noncompliance to the treatment independently contributed to the relapse rate. Functionality in late adolescence independently contributed to the Global Assessment of Functioning (GAF) scale score at one year and the GAF score at discharge appeared as a predictor of employment. The results of the present study suggest that treatment compliance and early premorbid adjustment level seem to be important predictors of relapse rate in first episode schizophrenia.