Interleukin 1β Decreases the GSH Content and Catalase Activity in the Human Peritoneal Mesothelial Cells in Vitro

The object of this study was to assess the effects of the inflammatory cytokine interleukin 1β (IL-1β) (0.01–1.0 ng/ml) on the activity of catalase (CAT), superoxide dismutase (SOD) and the level o f glutathione (GSH), all being antioxidant mechanisms, in human peritoneal mesothelial cells (HPMC) in in vitro c ulture. HPMC were obtained from the omenta of nonuremic donors. The activity of the antioxidant mechanisms was studied on monolayers of HPMC, which were deprived of serum 48 h prior to experiment. The effec t of the c ytokine was tested in a medium with low serum concentration (0.1%) or in a medium with 10% fe tal calf serum (FCS). Activity of the antioxidant mechanisms was determined by spectrophotometry. The GSH level was d ecreased in mesothelial cells (MC) after 24 h of exposition to IL-1. However, after 72 h of incubation with IL-1 t he GSH level increased in MC in the presence of 10% FCS, p<0.05. The activity of CAT was inhibited after 72 h e xposure to IL-1. Interleukin 1 did not affect SOD activity in MC. However, when supplemente d with 10% FCS, I L-1 decreased the activity of SOD after 24 and 72 h of incubation. We conclude that the acti vity of antioxidant mechanisms in MC is decreased by IL-1β in ways that might increase their vulnerability to the cytotoxic effect o f free radicals. K ey words: dialysis; inflammation; interleukin 1; antioxidants; catalase; superoxide.