REGULATION OF MACROPHAGE EICOSANOID GENERATION IS DEPENDENT ON NUCLEAR FACTOR KAPPA-B

Background: Prostaglandin E-2 (PGE(2)) is a major contributor to the p roduction and maintenance of immunosuppression after overwhelming inju ry, leading to increased infectious morbidity and mortality in trauma patients, Elucidation of the cellular pathways involved in PGE(2) prod uction could lead to potential therapeutic interventions. The purpose of this study was to determine the role of cyclooxygenase II (COX-2) i n PGE(2) production by MO and to investigate the cellular mechanism of COX-2 gene activation. Methods: Mouse macrophages (MO), RAW 264.7, we re exposed to Escherichia coli lipopolysaccharide (LPS) in the presenc e of cyclooxygenase inhibitors (ibuprofen or NS398), COX-1 and COX-2 m RNA expression and PGE(2) production were measured by Northern blot as say and enzyme-linked immunosorbent assay, respectively. Nuclear facto r K kappa (NF kappa B) activity was measured by electrophoretic mobili ty shift assay. To elucidate the role of NF kappa B in LPS-induced COX -2 gene activation, MO were exposed to LPS in the presence of an NF ka ppa B inhibitor, TPCK. Results: LPS increased MO COX-2 mRNA expression but had no effect on COX-I mRNA expression. Both ibuprofen and NS398 inhibited COX-2 mRNA as well as PGE(2) production by LPS-stimulated MO . In addition, LPS-induced NF kappa B activity was attenuated by these agents. Inhibition of NF kappa B with TPCK reduced COX-2 but not COX- 1 gene expression and decreased PGE(2) production by LPS-stimulated MO . Conclusion: Our data indicate that COX-2 gene expression by LPS-stim ulated MO is dependent on NF kappa B, Cyclooxygenase inhibitors reduce d PGE(2) production by inhibiting both COX-2 mRNA expression and preve nting NF kappa B activation.