Modulation by Progesterone of Interleukin-6 Production by Gingival Fibroblasts

The gingivitis associated with pregnancy has been attributed to increased concentrations of circulating estrogen and/or progesterone. However, the mechanism by which these steroids increase gingival inflammation is not known. Interleukin-6 (IL-6), a pleiotropic cytokine produced by many cell types including human gingival fibroblasts (hGF), is secreted in response to inflammatory challenges such as bacterial lipopolysaccharide and interleukin-1 (IL-1). This study tested the hypothesis that progesterone could modulate the local production of IL-6 by hGF. The effects of progesterone on IL-6 production were measured in vitro in serum-free, phenol red-free medium to eliminate possible effects of such medium additives. The concentration of IL-6 secreted into supernatant medium after a 24 hour challenge with IL-1β was estimated by radioimmunoassay. Total RNA from steroid-treated hGF was probed for IL-6 mRNA. In serum-free medium, progesterone dose-dependently and significantly (P <0.05) inhibited IL-6 productio...