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Background: Several lines of evidence have implicated the pro-inflammatory cytokine interleukin-1beta (IL-1 beta) in the etiology of schizophrenia. Although a number of genetic association studies have been reported, very few have systematically examined gene-wide tagging polymorphisms. Methods: A total of 533 patients with schizophrenia (302 males: mean age +/- standard deviation 43.4 +/- 13.0 years; 233 females; mean age 44.8 +/- 15.3 years) and 1136 healthy controls (388 males: mean age 44.6 +/- 17.3 years; 748 females; 46.3 +/- 15.6 years) were recruited for this study. All subjects were biologically unrelated Japanese individuals. Five tagging polymorphisms of IL-1 beta gene (rs2853550, rs1143634, rs1143633, rs1143630, rs16944) were examined for association with schizophrenia. Results: Significant difference in allele distribution was found between patients with schizophrenia and controls for rs1143633 (P = 0.0089). When the analysis was performed separately in each gender, significant difference between patients and controls in allele distribution of rs1143633 was observed in females (P = 0.0073). A trend towards association was also found between rs16944 and female patients with schizophrenia (P = 0.032). Conclusions: The present study shows the first evidence that the IL-1 beta gene polymorphism rs1143633 is associated with schizophrenia susceptibility in a Japanese population. The results suggest the possibility that the influence of IL-1 beta gene variations on susceptibility to schizophrenia may be greater in females than in males. Findings of the present study provide further support for the role of IL-1 beta in the etiology of schizophrenia., Article, BEHAVIORAL AND BRAIN FUNCTIONS. 7:35 (2011)

Background: Recently, hypothalamus-pituitary-adrenal (HPA) axis function assessed with the combined dexamethasone (DEX)/corticotropin releasing hormone (CRH) test has been shown to be associated with response to antidepressant treatment. A polymorphism (rs16944) in the interleukin-1beta (IL-1 beta) gene has also been reported to be associated with the medication response in depression. These findings prompted us to examine the possible association between IL-1 beta gene polymorphisms and HPA axis function assessed with the DEX/CRH test. Methods: DEX/CRH test was performed in 179 healthy volunteers (45 males: mean age 40.5 +/- 15.8 years; 134 females: mean age 47.1 +/- 13.2 years). Five tagging single nucleotide polymorphisms (SNPs) of IL-1 beta gene (rs2853550, rs1143634, rs1143633, rs1143630, rs16944) were selected at an r(2) threshold of 0.80 with a minor allele frequency > 0.1. Genotyping was performed by the TaqMan allelic discrimination assay. A two-way factorial analysis of variance (ANOVA) was performed with the DEX/CRH test results as the dependent variable and genotype and gender as independent variables. To account for multiple testing, P values < 0.01 were considered statistically significant for associations between the genotypes and the cortisol levels. Results: The cortisol levels after DEX administration (DST-Cortisol) showed significant associations with the genotypes of rs16944 (P = 0.00049) and rs1143633 (P = 0.0060), with no significant gender effect or genotype x gender interaction. On the other hand, cortisol levels after CRH administration (DEX/CRH-Cortisol) were affected by gender but were not significantly influenced by the genotype of the examined SNPs, with no significant genotype x gender interaction. Conclusions: Our results suggest that genetic variations in the IL-1 beta gene contribute to the HPA axis alteration assessed by DST-Cortisol in healthy subjects. On the other hand, no significant associations of the IL-1 beta gene polymorphisms with the DEX/CRH-Cortisol were observed. Confirmation of our findings in futures studies may add new insight into the communication between the immune system and the HPA axis., Article, BEHAVIORAL AND BRAIN FUNCTIONS. 7:23 (2011)