Aberrant methylation of the IL-12B promotor region contributes to the risk of developing ovarian endometriosis.

Studies have shown that aberrant expression of IL-12p40, which is encoded by the interleukin-12B (IL-12B) gene, may be involved in the development of endometriosis. In this study, we investigated the role of aberrant methylation of the IL-12B promoter region and its associated expression in the development of ovarian endometriosis. By using pyrosequencing, we analyzed the methylation level of the IL-12B promoter region in eutopic and ectopic endometrium of patients with ovarian endometriosis and normal endometrium of control women. The expression of IL-12B mRNA was detected by quantitative real-time PCR. The results showed that the methylation level of the IL-12B promoter region in ectopic and eutopic endometrium of patients with ovarian endometriosis was significantly lower than that in endometrium of women without endometriosis ( p < 0.001 and p = 0.041, respectively). In contrast, mRNA levels were significantly increased in ectopic and eutopic endometrium of patients with ovarian endometriosis compared to those in endometrium of women without endometriosis ( p < 0.001 and p = 0.042, respectively). Correlation analysis showed that the methylation level of the IL-12B promoter region was negatively correlated with mRNA levels of IL-12B ( p < 0.001). Our data suggested that aberrant methylation of the IL-12B promoter region may be responsible for aberrant IL-12B mRNA expression in endometrium tissue of women, which may be associated with the development of ovarian endometriosis in northern Chinese women.