Regulation of 15-lipoxygenase expression and mucus secretion by IL-4 in human bronchial epithelial cells.
Our laboratory has recently shown that mucus differentiation of cultured normal human tracheobronchial epithelial (NHTBE) cells is accompanied by the increased expression of 15-lipoxygenase (15-LO). We used differentiated NHTBE cells to investigate the regulation of 15-LO expression and mucus secretion by inflammatory cytokines. Interleukin (IL)-4 and IL-13 dramatically enhanced the expression of 15-LO, whereas tumor necrosis factor-alpha, IL-1beta, and interferon (IFN)-gamma had no effect. These cytokines did not increase the expression of cyclooxygenase-2, with the exception of a modest induction by IL-1beta. The IL-4-induced 15-LO expression was concentration dependent, and mRNA and protein expression increased within 3 and 6 h, respectively, after IL-4 treatment. In metabolism studies with intact cells, 15-hydroxyeicosatetraenoic acid (15-HETE) and 13-hydroxyoctadecadienoic acid (13-HODE) were the major metabolites formed from exogenous arachidonic acid and linoleic acid. No prostaglandins were detected. IL-4 treatment dramatically increased the formation of 13-HODE and 15-HETE compared with that in untreated NHTBE cells, and several additional 15-LO metabolites were observed. Pretreatment of NHTBE cells with IFN-gamma or dexamethasone did not inhibit the IL-4-induced expression of 15-LO except at high concentrations (100 ng/ml of IFN-gamma and 10 microM dexamethasone). IL-4 treatment inhibited mucus secretion and attenuated the expression of the mucin genes MUC5AC and MUC5B at 12-24 h after treatment. Addition of 15-HETE precursor and 13-HODE precursor to the cultures did not alter mucin secretion or mucin gene expression. On the basis of the data presented, we conclude that the increase in 15-LO expression by IL-4 and attenuation of mucus secretion may be independent biological events.
Jayawickreme
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SP
Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
Gray
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Nettesheim
P
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Eling
T
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D001093:Arachidonate 15-Lipoxygenase / Q000096:biosynthesis / Q000235:genetics*; D016718:Arachidonic Acid / Q000378:metabolism; D001980:Bronchi / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D002460:Cell Line; D051546:Cyclooxygenase 2; D004790:Enzyme Induction; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D018793:Interleukin-13 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology*; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D019787:Linoleic Acid / Q000378:metabolism; D008565:Membrane Proteins; D009093:Mucus / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D007375:Interleukin-1; D018793:Interleukin-13; D007527:Isoenzymes; D008565:Membrane Proteins; D014409:Tumor Necrosis Factor-alpha; D015847:Interleukin-4; D016718:Arachidonic Acid; D007371:Interferon-gamma; D019787:Linoleic Acid; D001093:Arachidonate 15-Lipoxygenase; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases