Abstract

These studies examined the signal transduction mechanisms by which prostaglandin (PG) E₂ production can occur in human amnionic WISH cells in response to the stimuli okadaic acid, interleukin (IL)-1β, tumor necrosis factor (TNF)-α, phorbol-12-myristate-13-acetate (PMA) or combinations of PMA with IL-1β or TNF-α. We also investigated whether WISH cells are capable of producing TNF-α or IL-1β in response to stimulation, because these cytokines can be produced in an autocrine fashion to perpetuate an inflammatory response. Our data indicate that the magnitude of PGE₂ production induced by a given stimulus correlated temporally with the level of PGH synthase-2 (PGHS-2) protein. PMA or IL-1β induced PGE₂ production 2 to 4 hr after treatment, whereas the combination of these agents produced the most rapid induction 2 hr after treatment. Only okadaic acid induced the production of both PGE₂ and TNF-α, after a lag of 12 to 18 hr. PGE₂ production by all stimuli was inhibited by dexamethasone, the IL-1 receptor antagonist (IL-1ra), the specific PGHS-2 inhibitor NS-398 and the protein kinase inhibitor staurosporin. In contrast, TNF-α production in response to okadaic acid was inhibited by the TNF-converting enzyme inhibitor GI 129471 and staurosporin but was unaffected by either IL-1ra, dexamethasone or NS-398. We conclude that WISH cells are capable of producing bioactive proinflammatory mediators such as TNF-α and PGE₂ through separable intracellular signal transduction mechanisms. The ability of IL-1ra to reduce PGE₂ production caused by all stimuli used suggests an autocrine role for IL-1 in PGHS-2 induction in these cells.