Effects of estrogen on interleukin-6 production in rheumatoid fibroblast-like synoviocytes.

Objective In view of the importance of estrogen and IL-6 in the pathogenesis of rheumatoid arthritis (RA), the effects of 17 β-estradiol (E2) on interleukin (IL)-6 production in cultured rheumatoid fibroblast-like synoviocytes were investigated. Methods Cultured fibroblast-like synoviocytes obtained from RA joints were treated with the vehicle (control), as well as 10 -8 and 10 -6 M of E2, with or without IL-1β stimulation. After 72 hours of culture, the levels of IL-6 in supernatants were measured by ELISA. Results Treatment with 10 -8 and 10 -6 M of E2 had no effect on the constitutive production of IL-6 in cultured fibroblast-like synoviocytes. However, E2 increased IL-1β-induced IL-6 production in a dose-dependent manner, with a mean 12.5% increase with 10 -8 M of E2 (p = 0.048) and 33.4% with 10 -6 M (p < 0.0001) versus the control. Conclusion Estrogen up-regulates IL-1β-induced IL-6 production in cultured fibroblast-like synoviocytes, possibly contributing to the enhancement of rheumatoid inflammation in synovial tissues.