The Role of 12/15-Lipoxygenase in the Expression of Interleukin-6 and Tumor Necrosis Factor-α in Macrophages

• Published in: Endocrinology (Philadelphia) 2007-03, Vol.148 (3), p.1313-1322
• Main Authors: Wen, Yeshao, Gu, Jiali, Chakrabarti, Swarup K, Aylor, Kevin, Marshall, John, Takahashi, Yoshitaka, Yoshimoto, Tanihiro, Nadler, Jerry L
• Format: Article
• Language: English
• Subjects: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid - pharmacology; Acids; Adenine; Animals; Arachidonate 12-lipoxygenase; Arachidonate 12-Lipoxygenase - genetics; Arachidonate 12-Lipoxygenase - physiology; Arachidonate 15-Lipoxygenase - genetics; Arachidonate 15-Lipoxygenase - physiology; Arteriosclerosis; Atherosclerosis; Cell culture; Cells, Cultured; Cytokines; Gene expression; In vitro methods and tests; In vivo methods and tests; Inflammation; Interleukin 6; Interleukin-6 - metabolism; Kinases; Lipoxygenase; Macrophages; Macrophages - drug effects; Macrophages - metabolism; Male; MAP kinase; MAP Kinase Kinase 4 - physiology; Mice; Mice, Inbred C57BL; Mice, Transgenic; Models, Biological; Monocyte chemoattractant protein; Monocytes; NAD(P)H oxidase; NADPH Oxidases - metabolism; NADPH-diaphorase; Nicotinamide; Nicotinamide adenine dinucleotide; p38 Mitogen-Activated Protein Kinases - physiology; Protein kinase C; Protein Kinase C - physiology; Proteins; Transcription factors; Transfection; Transgenic animals; Transgenic mice; Tumor Necrosis Factor-alpha - metabolism; Tumor necrosis factor-TNF; Tumor necrosis factor-α
• ISSN: 0013-7227; 1945-7170
• DOI: 10.1210/en.2006-0665

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-α 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-α 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-1β, 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 NH2-terminal kinase as well as nicotinamide adenine dinucleotide phosphate oxidase are important for 12-(S)-hydroxyeicosatetraenoic acid-induced increases in IL-6 and TNF-α gene expression. These results suggest a potentially important mechanism linking 12/15-LO activation to chronic inflammation and atherosclerosis.