title: Activation of a 15-lipoxygenase/leukotriene pathway in human polymorphonuclear leukocytes by the anti-inflammatory agent ibuprofen.
abstract: Human peripheral blood polymorphonuclear leukocytes (PMNs) metabolized [14C]arachidonic acid predominantly by lipoxygenase pathways. The major products were 5-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE) and 15-HETE. These and other lipoxygenase products, including their derived leukotrienes, have been implicated as mediators of inflammatory and allergic reactions. In human platelets, the nonsteroidal anti-inflammatory drug ibuprofen inhibited production of the cyclooxygenase product thromboxane B2 (I50 = 65 microM), whereas the lipoxygenase product 12-HETE was not appreciably affected even at 5 mM ibuprofen. The 5-lipoxygenase of human PMNs (measured by 5-HETE formation) was inhibited by ibuprofen but was about six times less sensitive (I50 = 420 microM) than the platelet cyclooxygenase. The unexpected observation was made that the human PMN 15-lipoxygenase/leukotriene pathway was selectively activated by 1-5 mM ibuprofen. Metabolites were identified by ultraviolet spectroscopy, by radioimmunoassay, or by retention times on high pressure liquid chromatography in comparison with authentic standards. The major product was 15-HETE; and in all of 19 donors tested, 15-HETE formation was stimulated up to 20-fold by 5 mM ibuprofen. Other identified products included 12-HETE and 15- and 12-hydroperoxyeicosatetraenoic acid. Activation of the 15-lipoxygenase by ibuprofen occurred within 1 min and was readily reversible. The effects of aspirin, indomethacin, and ibuprofen on the PMN 15-lipoxygenase were compared in six donors. Ibuprofen produced an average 9-fold stimulation of the enzyme, whereas aspirin and indomethacin resulted in an average 1.5- and 2-fold enhancement, respectively.
mesh_terms: D001091:Arachidonate Lipoxygenases; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood; D004789:Enzyme Activation; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids; D007052:Ibuprofen / Q000494:pharmacology*; D008084:Lipoxygenase / Q000097:blood*; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000097:blood; D013189:SRS-A / Q000097:blood*
chemical_list: D001095:Arachidonic Acids; D006893:Hydroxyeicosatetraenoic Acids; D013189:SRS-A; D016718:Arachidonic Acid; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D001091:Arachidonate Lipoxygenases; D008084:Lipoxygenase; D011451:Prostaglandin-Endoperoxide Synthases; D007052:Ibuprofen