Agonist-Induced Expression of Tissue Inhibitor of Metalloproteinases and Metalloproteinases by Human Macrophages Is Regulated by Endogenous Prostaglandin E2 Synthesis

Abstract

The regulatory effect of endogenously synthesized eicosanoid metabolites on the expression of tissue inhibitor of metalloproteinases (TIMP), interstitial collagenase, and 92-kDa gelatinase by human macrophages was examined. TIMP and metalloproteinase production were stimulated with three agonists that produce distinct patterns of eicosanoid synthesis: lipopolysaccharide (10 micrograms/ml), denatured collagen (10 micrograms/ml), or zymosan (1 mg/ml). Indomethacin (3 micrograms/ml) or MK886 (3 microM), a specific inhibitor of 5-lipoxygenase, was used to examine the role of endogenous metabolites of arachidonic acid. Regardless of the agonist used, TIMP production by macrophages was inhibited 65% by indomethacin, synthesis of interstitial collagenase was reduced 70%, and expression of 92-kDa gelatinase was decreased 40%. In contrast, inhibition of leukotriene synthesis had no effect on metalloproteinase or TIMP production. The agonist-stimulated increase in TIMP and collagenase production was directly correlated to the cumulative prostaglandin E2 level induced by the agonist used. However, if response to an agonist was poor, the exogenous addition of prostaglandin E2 could not increase TIMP or collagenase production more than twofold, indicating an important permissive effect of the agonist on the regulation of each protein's expression. The mechanism of indomethacin inhibition of TIMP and collagenase production was studied by labeling the cells with [35S]-methionine and performing immunoprecipitation using specific antiserum. Indomethacin markedly inhibited the lipopolysaccharide-induced biosynthesis of both TIMP and collagenase. Northern analysis revealed parallel suppression of TIMP and collagenase steady-state mRNA levels by indomethacin, indicating pretranslational control. The regulation of inflammatory-cell TIMP and interstitial collagenase expression by prostaglandin E2 suggests that therapy inhibiting the cellular response to prostaglandins may be useful in cutaneous and systemic disease states involving macrophage-mediated connective-tissue destruction.