Lipoxygenases in corneal epithelia of man and cynomolgus monkey

Human and monkey corneal epithelia were investigated for lipoxygenases. The low-speed supernatant of human corneal epithelium converted arachidonic acid to one prominent metabolite, which was identified as 15-hydroxyeicosatetraenoic acid by gas chromarography mass spectrometry and by ultra violet analyses. Eicosatetraynoic acid, a lipoxygenase inhibitor, reduced the formation of 15-hydroxyeicosatetraenoic acid, by 90% at 30 microM, while esculetin (30 microM) and diclofenac (100 microM) did not inhibit the biosynthesis. Immunohistochemical analysis of human cornea using a polyclonal antibody against recombinant human reticulocyte 15-lipoxygenase showed staining of the epithelium, but not the stroma. The cytosolic fraction of epithelial cells of the monkey, Macaca fascicularis, converted [1-14C]arachidonic acid to two major metabolites, which were identified as 15S-hydroxyeicosatetraenoic and 12S-hydroxyeicosatetraenoic acids by cochromatography with these compounds on reverse-phase, straight-phase and chiral high-performance liquid chromatography. Lipoxygenase activity could not be detected in the microsomal fraction. The results provide biochemical, pharmacological and immunohistological evidence of a 15-lipoxygenase in human corneal epithelium and suggest that monkey corneal epithelium contains cytosolic 12- and 15-lipoxygenases.