title: A lipid peroxidation-derived inflammatory mediator: identification of 4-hydroxy-2-nonenal as a potential inducer of cyclooxygenase-2 in macrophages.
abstract: Cyclooxygenases (COXs) catalyze the conversion of arachidonic acid to eicosanoids, which mediate a variety of biological actions involved in vascular pathophysiology. In the present study, we investigated the role of lipid peroxidation products in the up-regulation of COX-2, an inducible isoform responsible for high levels of prostaglandin production during inflammation and immune responses. COX-2 was found to colocalize with 4-hydroxy-2-nonenal (HNE), a major lipid peroxidation-derived aldehyde, in foamy macrophages within human atheromatous lesions, suggesting that COX-2 expression may be associated with the accumulation of lipid peroxidation products within macrophages. To test the hypothesis that lipid peroxidation products might be involved in the regulation of prostanoid biosynthesis, we conducted a screen of oxidized fatty acid metabolites and found that, among the compounds tested, only HNE showed inducibility of the COX-2 protein in RAW264.7 macrophages. In addition, intraperitoneal administration of HNE resulted in an increase in cell numbers in the peritoneal cavity that was associated with significant increases in the peritoneal and tissue levels of COX-2 in mice. To understand the possible signaling mechanism underlying the inducing effect of HNE on COX-2 up-regulation, we examined the phosphorylation events that may lead to COX-2 induction and found that HNE did not stimulate the induction of nitric oxide synthase and activation of NF-kappaB but significantly activated p38 mitogen-activated protein kinase and its upstream kinase in RAW264.7 macrophages. Tyrosine kinases, such as the epidermal growth factor-like and Src family tyrosine kinases, appeared to mediate the stabilization of COX-2 mRNA via the p38 mitogen-activated protein kinase pathway. These findings suggest that HNE accumulated in macrophages/foam cells may represent an inflammatory mediator that plays a role in stimulation of the inflammatory response and contributes to the progression of atherogenesis.
authors.affiliation: Graduate School of Bioagricultural Sciences and Institute for Advanced Research, Nagoya University, Nagoya, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kumagai
authors.forename: Nao
authors.initials: N
authors.lastname: Matsukawa
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Kaneko
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kusumi
authors.forename: Masako
authors.initials: M
authors.lastname: Mitsumata
authors.forename: Koji
authors.initials: K
authors.lastname: Uchida
mesh_terms: D000447:Aldehydes / Q000276:immunology / Q000494:pharmacology*; D000818:Animals; D001161:Arteriosclerosis / Q000378:metabolism / Q000473:pathology; D002460:Cell Line; D003331:Coronary Vessels / Q000378:metabolism / Q000473:pathology; D051546:Cyclooxygenase 2; D004789:Enzyme Activation; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000276:immunology / Q000494:pharmacology*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D015227:Lipid Peroxidation; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000201:enzymology*; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D020871:RNA Stability; D015398:Signal Transduction / Q000502:physiology; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D000447:Aldehydes; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D016328:NF-kappa B; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019061:src-Family Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C027576:4-hydroxy-2-nonenal