title: The role of 12/15-lipoxygenase in the expression of interleukin-6 and tumor necrosis factor-alpha in macrophages.
abstract: 12/15-lipoxygenase (12/15-LO) enzyme and products have been associated with inflammation and atherosclerosis. However, the mechanism of effects of the 12/15-LO products has not been fully clarified. To study the role of 12/15-LO in cytokine expression, experiments with direct additions of the12/15-LO products, 12(S)-hydroxyeicosa tetraenoic acid or 12(S)-hydroperoxyeicosa-5Z, 8Z, 10E, or 14Z-tetraenoic acid to macrophages were first carried out, and results showed that the 12/15-LO products stimulated mRNA and protein expression of IL-6 and TNF-alpha in a dose-dependent manner. In contrast, an inactive analogue of 12(S)-hydroxyeicosa tetraenoic acid had no effect. To further explore the role of endogenous 12/15-LO in cytokine expression, we used an in vitro and in vivo model to test the effect of 12/15-LO overexpression. The models included Plox-86 cells, a J774A.1 cell line that stably overexpresses leukocyte-type 12/15-LO and primary mouse peritoneal macrophages (MPMs) from 12/15-LO transgenic mice. The results showed a clear increase in IL-6 and TNF-alpha expression in Plox-86 cells and MPMs from 12/15-LO transgenic mice, compared with mock-transfected J774A.1 cells and MPMs from control C57BL6 mice. IL-1beta, IL-12, and monocyte chemoattractant protein (MCP)-1 mRNA were also increased in Plox-86 cells. These data clearly suggest a clear role of 12/15-LO pathway in cytokine production. We also demonstrated that signaling pathways including protein kinase C, p38 MAPK (p38), c-jun NH(2)-terminal kinase as well as nicotinamide adenine dinucleotide phosphate oxidase are important for 12-(S)-hydroxyeicosatetraenoic acid-induced increases in IL-6 and TNF-alpha gene expression. These results suggest a potentially important mechanism linking 12/15-LO activation to chronic inflammation and atherosclerosis.
authors.affiliation: Diabetes and Hormone Center, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Yeshao
authors.initials: Y
authors.lastname: Wen
authors.forename: Jiali
authors.initials: J
authors.lastname: Gu
authors.forename: Swarup K
authors.initials: SK
authors.lastname: Chakrabarti
authors.forename: Kevin
authors.initials: K
authors.lastname: Aylor
authors.forename: John
authors.initials: J
authors.lastname: Marshall
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Tanihiro
authors.initials: T
authors.lastname: Yoshimoto
authors.forename: Jerry L
authors.initials: JL
authors.lastname: Nadler
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000494:pharmacology; D000818:Animals; D001092:Arachidonate 12-Lipoxygenase / Q000235:genetics / Q000502:physiology*; D001093:Arachidonate 15-Lipoxygenase / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D015850:Interleukin-6 / Q000378:metabolism*; D048670:MAP Kinase Kinase 4 / Q000502:physiology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008954:Models, Biological; D019255:NADPH Oxidases / Q000378:metabolism; D011493:Protein Kinase C / Q000502:physiology; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
chemical_list: C475064:12-15-lipoxygenase; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D001092:Arachidonate 12-Lipoxygenase; D001093:Arachidonate 15-Lipoxygenase; D019255:NADPH Oxidases; D011493:Protein Kinase C; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4