Prostaglandin H-Synthase-2 Is the Main Enzyme Involved in the Biosynthesis of Octadecanoids from Linoleic Acid in Human Dermal Fibroblasts Stimulated with Interleukin-1β

This study was focused on the characterization of the metabolism of linoleic acid by human dermal fibroblasts and the effect of interleukin-1 on the biosynthesis of octadecanoids. Dermal fibroblasts untreated and treated with recombinant IL-1β were incubated with exogenous labeled linoleic acid. A combination of high–performance liquid chromatography and gas chromatograph–mass spectrometry was used as the analytic techniques. We found that dermal fibroblasts convert linoleic acid mainly into 13-hydroxy-9-cis,11-trans-octadecadienoic acid (13-HODE) and 9-hydroxy-10-trans,12-cis-octadecadienoic acid (9-HODE), 13(S)-RODE and 9(R)-HODE being the predominant enantiomers. IL-1β increased the formation of both 13-HODE and 9-HODE in a concentration-dependent manner with similar EC50 values as for prostanoid formation. This effect of IL-1β on HODEs formation was concomitant with the expression of prostaglandin H-synthase-2. Formation of octadecanoids was inhibited in a concentration-dependent manner by acetylsalicylic acid and indomethacin. Dexamethasone, actinomycin, and cycloheximide abolished the effect of IL-1β on HODEs biosynthesis. Octadecanoid biosynthetic activity was associated with the microsomal fraction. Dermal fibroblasts incorporated [14C]-9-HODE and [14C]-13-HODE into phospholipids, mainly into phosphatidylcholine. IL-1β increased significantly the esterification of 13-HODE in all glycerophospholipids, the major increase being observed in phosphatidylinositol. These results indicate that prostaglandin H-synthase-2 is the enzyme responsible for the increase in the ability to from HODEs of dermal fibroblasts stimulated with IL-1β.