Interferon Gamma Antagonizes Interleukin-1β-Induced Cyclooxygenase-2 Expression and Prostaglandin E2 Production in Human Myomaterial Cells

Abstract

Objective: To evaluate the effect of interferon γ (IFNγ) on interleukin-1β (IL-1) and tumor necrosis factor-α (TNFα)-promoted prostaglandin E₂ (PGE₂) production and to investigate the interaction of IFNγ and IL-1 on cyclooxygenase-2 (COX-2) expression, as well as nuclear factor-κB (NF-κB) activation in human myometrical cells.

Methods: 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 E₂ was determined in the medium with a specific radioimmunoassay having a sensitivity of 10 pg. The COX-2 and NF-κB inhibitory protein (IκB) protein levels were measured in cell extracts by Western blot.

Results: Cell cultures primed with IFNγ produced significantly less (P < .05-.01) PGE₂ in response to cytokines than cells exposed to IL-1, TNF-α, or the combination of the two. This result corresponded to a similar inhibition of IκB degradation (a prerequisite of NF-κB activation) as well as COX-2 protein steady state levels.

Conclusion: Interferon γ acts as a partial antagonist of IL-1 signaling in this cell model at a site upstream from the activation of the NF-κB pathway, causing a partial inhibition of COX-2 expression and PGE₂ production.