8(S)-hydroxyeicosatetraenoic acid is the lipoxygenase metabolite of arachidonic acid that regulates epithelial cell migration in the rat cornea.
BACKGROUND: We previously found that the inhibition of lipoxygenases resulted in delayed epithelial wound closure in organ-cultured rat corneas. The present study was undertaken to determine the lipoxygenase enzyme and metabolite(s) responsible for regulating reepithelialization and their mechanism of action. METHODS: The effects of esculetin--an established lipoxygenase inhibitor--on endogenous hydroxyeicosatetraenoic acids (HETEs) production, epithelial wound closure, filamentous-actin (F-actin) cytoskeleton, and mitotic rate were investigated using a cell-culture assay and an organ-culture assay of rat corneal epithelium. RESULTS: Lipoxygenase inhibition by esculetin, which resulted in the disruption of F-actin organization and a decrease in the mitotic rate, delayed wound closure in both cell- and organ-culture assays. Normal corneoscleral rims metabolized [3H]arachidonic acid to 12-HETE (major metabolite), 8-HETE, and 9-HETE. HETE synthesis was inhibited by esculetin in a dose-dependent fashion. Chiral-phase analysis revealed that they contained only (S)-enantiomers, which indicated that they were lipoxygenase metabolites. The inhibitory effects of esculetin on F-actin organization and epithelial wound closure in an organ-culture assay were totally reversed by exogenously added 8(S)-HETE, whereas 12- and 9-HETE had no effect. However, none of the HETEs reversed the decreased mitotic rate or achieved complete wound closure in the cell-culture assay. CONCLUSIONS: These results suggest that 8(S)-HETE is the key metabolite of arachidonic acid that regulates corneal epithelial cell migration during wound healing. The metabolite responsible for cell proliferation remains to be determined.
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