The Pattern of Methylation and Polymorphism in Interleukin-6 Promoter Gene Are Related to the Development of Rheumatoid Arthritis?

Rheumatoid Arthritis (RA) is a complex disease with higher level of IL-6. In order to elucidate the alterations related to IL-6 gene in RA, we evaluated the -174 G/C IL-6 gene polymorphism and methylation pattern of its promoter. A total of 120 RA patients and 120 healthy controls were recruited for polymorphism analysis, and 30 individuals of both groups were randomly selected for methylation analysis. The IL-6 gene polymorphism was analyzed by PCR-RFLP and methylation pattern was analyzed by MSP-PCR. Regarding IL-6 gene polymorphism, no significant difference was found between RA patients and controls (P 0.05). For DNA, two CpG regions of IL-6 promoter gene was analyzed. The first region (−1069, −1061, −1057 and −1001 CpG) did not show significant differences, whereas the second region (−628, −610, −574 and −491 CpG) showed a significant hypermethylated status (P=0.0004) in RA patients as compared with controls.These results, suggest a possible relationship between methylation pattern and the susceptibility to RA in our studied population.