Interleukin-10 promoter polymorphisms influence susceptibility to ulcerative colitis in a gender-specific manner

Objective. Pathological evidence supports a potential role of the pro- and anti-inflammatory cytokine network in the pathogenesis of inflammatory bowel disease (IBD). Moreover, associated studies suggest a possible involvement of cytokine-related genes in IBD susceptibility. In this study, we evaluated the effect of the anti-inflammatory interleukin-10 (IL10) gene on ulcerative colitis (UC). Material and methods. Two functional single nucleotide polymorphisms (-1082 G/A, -819 T/C) in the IL10 promoter in 203 Italian sporadic UC patients and 391 controls were determined using high-resolution melting analysis. Results. The frequency of the -1082A allele was significantly higher in the UC patients than in controls (p=0.00003); -1082 genotype frequencies were also significantly different between UC patients and controls (p=0.0001). Allele and genotype frequencies of -819 T/C were not significantly associated with UC. Furthermore, the frequencies of haplotypes -1082A/-819C and -1082A/-819T, which have been reported to have a lower promoter activity, were significantly higher in UC patients than in controls (p=0.0004). After gender stratification, we found a significant difference in the -1082A allele (p=0.00004) and genotype (p=0.0002) frequencies only between female UC patients and controls; the same result was obtained for the -1082A/-819C and -1082A/-819T haplotypes (p=0.0006). Conclusions. A gender effect is observed, with women of AG/AA IL10 genotypes and AC/AT haplotypes having a higher risk of developing UC at a younger age. This finding could be related to the previously documented lower IL10 production associated with the -1082A allele and to the IL10 down-regulating effect of estrogens.