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 result ed in delayed epithelial wound closure in organ-cultured rat corneas. The p resent study was undertaken to determine the lipoxygenase enzyme and metabo lite(s) responsible for regulating reepithelialization and their mechanism of action. Methods. The effects of esculetin-an established lipoxygenase in hibitor-on endogenous hydroxyeicosatetraenoic acids (HETEs) production, epi thelial wound closure, filamentous-actin (F-actin) cytoskeleton, and mitoti c rate were investigated using a cell-culture assay and an organ-culture as say of rat corneal epithelium. Results. Lipoxygenase inhibition by esculeti n, which resulted in the disruption of F-actin organization and a decrease in the mitotic rare, delayed wound closure in both cell- and organ-culture assays. Normal corneoscleral rims metabolized [H-3]arachidonic acid to 12-H ETE (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 lipoxy genase metabolites. The inhibitory effects of esculetin on F-actin organiza tion and epithelial wound closure in an organ-culture assay were totally re versed 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 achieve d complete wound closure in the cell-culture assay. Conclusions. These resu lts suggest that 8(S)-HETE is the key metabolite of arachidonic acid that r egulates corneal epithelial cell migration during wound healing. The metabo lite responsible for cell proliferation remains to be determined.