Interferon gamma antagonizes interleukin-1beta-induced cyclooxygenase-2 expression and prostaglandin E(2) production...

To evaluate the effect of interferon gamma (IFNgamma) on interleukin-1beta (IL-1) and tumor necrosis factor-alpha (TNFalpha)-promoted prostaglandin E(2) (PGE(2)) production and to investigate the interaction of IFNgamma and IL-1 on cyclooxygenase-2 (COX-2) expression, as well as nuclear factor-kappaB (NF-kappaB) activation in human myometrial cells.

An immortalized human myometrial cell line was cultured in Dulbecco modified Eagle medium (DMEM) fortified with 10% (v/v) fetal calf serum (FCS) in multiwell plates until near confluency. Twenty-four hours before the start of the experiments, the medium was replaced with FCS-free medium containing 0.5% bovine serum albumin. Prostaglandin E(2) was determined in the medium with a specific radioimmunoassay having a sensitivity of 10 pg. The COX-2 and NF-kappaB inhibitory protein (IkappaB) protein levels were measured in cell extracts by Western blot.

Cell cultures primed with IFNgamma produced significantly less (P <.05-.01) PGE(2) in response to cytokines than cells exposed to IL-1, TNF-alpha, or the combination of the two. This result corresponded to a similar inhibition of IkappaB degradation (a prerequisite of NF-kappaB activation) as well as COX-2 protein steady state levels.

Interferon gamma acts as a partial antagonist of IL-1 signaling in this cell model at a site upstream from the activation of the NF-kappaB pathway, causing a partial inhibition of COX-2 expression and PGE(2) production.