TAURINE CHLORAMINE INHIBITS PROSTAGLANDIN E(2) PRODUCTION IN ACTIVATED RAW-264.7 CELLS BY POSTTRANSCRIPTIONAL EFFECTS ON INDUCIBLE CYCLOOXYGENASE EXPRESSION

Taurine chloramine (Tau-Cl) was recently demonstrated to inhibit produ ction of nitric oxide and tumor necrosis factor-alpha (TNF-alpha) by a ctivated macrophages. Since increased production of prostaglandin E(2) (PGE(2)), a reaction catalyzed by induction of cyclooxygenase-2 (COX- 2), is also associated with the inflammatory response, we determined t he effects of Tau-Cl on PGE(2) production and on expression of COX-2 p rotein and COX-2 mRNA in activated RAW 264.7 cells, a murine macrophag e-like cell line. Tau-Cl inhibited production of PGE(2) in a concentra tion dependent manner with an IC50 of 0.4 mM. The decrease in PGE(2) p roduction was largely accounted for by decreased expression of COX-2 p rotein. Although the kinetics of COX-2 mRNA expression was altered in Tau-Cl treated cells, mRNA expression appeared to be quantitatively un impaired. These results suggest that Tau-Cl affects the post-transcrip tional regulation of COX-2 expression and support the idea that Tau-Cl may function as an inhibitory modulator of the inflammatory response.