Biosynthesis of eoxin C4 by porcine leukocytes

Human 15-lipoxygenase-1 (LO) possesses mainly 15-lipoxygenase activity whereas the animal ortholog 12/15-LO possesses mainly 12-lipoxygenase activity. These findings have raised the question if studies on animals can predict the function of 15-LO-1 in human. In this study we have characterized the arachidonic acid metabolites formed by porcine 12/15-LO. Mini pigs were infected with a parasite to increase the number of blood eosinophils, which highly express 12/15-LO. Isolated porcine polymorphonuclear leukocytes (PMNL) were incubated with arachidonic acid and the produced metabolites were analysed with HPLC and mass spectrometry (MS). The cells were found to produce 15-hydroxyeicosatetraenoic acid (HETE) and 12-HETE at a ratio of 1:5. Furthermore 8,15-dihydroxyeicosatetraenoic acids (DiHETEs) and 14,15-DiHETE were formed. Based on HPLC, UV-spectroscopy and MS analysis it was found that porcine PMNL also produced eoxin (EX) C4. These results demonstrate that although porcine 12/15-LO possesses primarily 12-lipoxygenase activity, the enzyme can catalyse the formation of EXC4.