Association Between IL-10 Gene Promoter Polymorphisms And Endometriosis

BACKGROUNDEndometriosis is a common benign disease whose etiology is still unknown. However, there is increasing evidence that genetic susceptibility is a risk factor for the development of the disease. It is generally accepted that endometriosis is inherited as a complex genetic trait, in which multiple gene loci interact with each other and the environment to produce the disease phenotype.The failure of the immune system to eliminate implanted endometrial cells has been suggested to contribute to the development and progression of endometriosis. Cytokine, the active factor in immunologic regulation, may play a central role in endometriosis.Many studies have shown that patients with endometriosis have increased IL-10 levels in the peritoneal fluid, inferring that IL-10 maybe important in the pathogenesis of endometriosis. The capacity for IL-10 production in individuals has a major genetic component. There are striking differences between individuals in their ability to produce IL-10 following lipopolysaccharide stimulation of whole-blood cultures in vitro. This is the result of differing rates of IL-10 mRNA synthesis, which has been ascribed to the polymorphisms in the IL-10 gene promoter.Three biallelic polymorphisms at positions -1082, -819, and —592 from the transcription start site have been described, which induce different transcription activity and IL-10 production. Among the three sites, the polymorphism in -1082 site may have more influence in the production of IL-10 protein than the other two sites. It is believed that GCC/GCC haplotype is associated with high IL-10 level; GCC/ACC and GCC/ATA haplotypes with intermediate IL-10 production and ACC/ACC, ACC/ATA, and ATA/ATA hapotypes with the lowest level of IL-10 protein, respectively. Furthermore, the distribution of polymorphisms in IL-10 promoter may be varied in different ethnic populations and areas.In the present study, we have explored the relationship between the polymorphisms of IL-10 promoter and IL-10 levels in serum and peritoneal fluid. The aim of this study is to investigate whether IL-10 gene promoter polymorphisms may be one of the reasons for the susceptibility to endometriosis in Chinese population, and for the IL-10 protein levels in vivo.MATERIALS AND METHODS1. Clinical specimen and DNA isolationGenomic DNA was extracted from blood lymphocytes of 119 Chinese women undergoing laproscopy and laprorectomy for endometriosis in Women's hospital, School of Medicine, Zhejiang University. The control group consisted of 84 women who underwent reananstomosis (60) or teratoma (24) without pelvic endometriosis and adenomyosis evidenced by laproscopy or laprorectomy.2. GenotypingARMS-PCR (Amplification Refractory Mutation System Polymerase chain reactions) and DNA sequencing were performed to detect polymorphism of-1082 site; PCR-RFLP was used to determine the genotypes in -819 and -592 sites.3.Determination the serum and peritoneal fluid IL-10 levels by ELISAThe serum and peritoneal fluid IL-10 levels were determined in 96 EMs patients and 80 controls by ELISA.4.Statistical analysisKruskal-Wallis H, chi-square, T-test, Mann-Whitney U, Wilcoxon and Spearman rank correlation analysis were used for statistical analysis, two-tailed test with p<0.05 were considered significant. All data were managed with SPSS 12.0 for windows.RESULTS1. There were no significant differences in the polymorphism of-1082 site between all groups (P>0.05). The frequencies of-819C, -592C alleles and -819 CC+TC, -592 CC+AC genotypes were significantly increased in EMs patients compared with controls (P<0.05). The frequencies of-819C, -592C alleles and -819CC+TC, -592 CC+AC genotypes were significantly increased in III-IV EMs patients compared with I - II EMs and controls(p<0.01).2. Three kinds of haplotypes (GCC, ACC and ATA) were found. ATA/ATA, ATA/ACC and ACC/ACC were the most popular haplotypes; GCC/ACC and GCC/ATA were less and GCC/GCC was the least.3. The median concentrations of IL-10 in peritoneal fluid were significantly higher in EMs group than controls (P<0.