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.