In view of the importance of estrogen and IL-6 in the pathogenesis of rheumatoid arthritis (RA), the effects of 17 beta-estradiol (E2) on interleukin (IL)-6 production in cultured rheumatoid fibroblast-like synoviocytes were investigated.
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-1 beta stimulation. After 72 hours of culture, the levels of IL-6 in supernatants were measured by ELISA.
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-1 beta-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.
Estrogen up-regulates IL-1 beta-induced IL-6 production in cultured fibroblast-like synoviocytes, possibly contributing to the enhancement of rheumatoid inflammation in synovial tissues.