human monocytic cells

Abstract: The fungal metabolite trichodimerol (BMS-182123) has demonstrated inhibition of lipopolysaceharide (LPS)-stimulated tumor necrosis factor-a (TNF-a) secretion in various in vitro macro-phage models (human and murine) including primary and tumor cell lines. When challenged with LPS, differentiated THP- 1 monocytic cells secrete ele-vated levels of the cyclooxygenase products pro-staglandin E2 (PGE2), thromboxane B2, and prostaglandin F2ct (PGF2a). Studies directed at elu-cidating the mechanism ofaction ofBMS-182123 as a TNF-ct inhibitor revealed that the compound has a profound inhibitory effect on prostanoid secretion in response to LPS challenge. The key enzymes in prostaglandin synthesis are the constitutive cy-clooxygenase, prostaglandin H synthase-1 (PGHS-1), and the mitogen-induced cyclooxygenase (PGHS-2), which is induced upon LPS stimulation in THP-1 cells. BMS-182123 did not inhibit the cy-clooxygenase activity of PGHS- 1 in an in vitro assay, suggesting that inhibition is due to a blockade in synthesis of cyclooxygenase enzyme. Western blot analysis of microsomal pellets from THP- 1 cells stimulated with LPS (with or without BMS-182123 pretreatment) provided convincing evidence that the inhibition of prostaglandin synthesis is a result of suppressed synthesis of PGHS-2 enzyme. Northern blot analysis of THP- 1 RNA demonstrated that BMS-182 1 23 inhibits the induction of PGHS-2 at the level of transcription. J. Leukoc. Biol. 60: 271-277