Prostaglandin H-synthase-2 is the main enzyme involved in the biosynthesis of octadecanoids from linoleic acid in human dermal fibroblasts stimulated with interleukin-1 beta

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-1 beta were incubated with exogenous labeled linoleic acid. A combination of high performance liquid chromatography and gas chromatography-mass spectrometry was used as the analytic technique. 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)-HODE and 9(R)-HODE being the predominant enantiomers. IL-1 beta increased the formation of both 13-HODE and 9-HODE in a concentration-dependent manner with similar EC(50) values as for prostanoid formation, This effect of IL-1 beta 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 D, and cycloheximide abolished the effect of IL-1 beta on HODEs biosynthesis, Octadecanoid biosynthetic activity was associated with the microsomal fraction. Dermal fibroblasts incorporated [C-14]-9-HODE and [C-14]-13-HODE into phospholipids, mainly into phosphatidylcholine. IL-1 beta 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 form HODEs of dermal fibroblasts stimulated with IL-1 beta.