Involvement of Prostaglandin E and Adenosine 3′ 5′‐Monophosphate in Lipopolysaccharide‐Stimulated Collagenase Release by Rat Kupffer Cells

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Abstract
Rat Kupffer cells exposed to bacterial [Salmonella] lipopolysaccharide in vitro synthesized collagenase and released the major portion of it into the extracellular space while the intracellular level of enzyme was not altered significantly. Cycloheximide prevented the appearance of collagenase in the medium indicating de novo synthesis. Indomethacin, an inhibitor of cyclooxygenase, also blocked collagenase synthesis. In line with this observation, Kupffer cells were found to synthesize substantial amounts of prostaglandin E2 when exposed to lipopolysaccharide and cellular cAMP levels were increased. Indomethacin abolished the stimulated cAMP formation. Addition to the culture medium of cAMP or dibutyryl-cAMP as well as of prostaglandin E2 or, to a lesser extent, prostaglandin E1 allowed indomethacin-inhibited cells to resume the production of collagenase. Evidently, in rat Kupffer cells lipopolysaccharide-elicited collagenase synthesis and excretion is mediated sequentially by stimulated production of prostaglandin E2, enhanced adenylate cyclase activity and increased intracellular cAMP levels.