title: Hydrogen peroxide enhances shedding of type I soluble tumor necrosis factor receptor from pulmonary epithelial cells.
abstract: Reactive oxygen intermediates (ROIs) are among the important mediators in the pathogenesis of lung diseases in which tumor necrosis factor (TNF) plays a pivotal role. However, the effects of ROIs on the TNF- TNF receptor system remain unclear. Effects of hydrogen peroxide on the shedding of soluble tumor necrosis factor receptor (sTNF-R) were investigated in a pulmonary epithelial cell line (A549) using enzyme-linked immunoassay. A549 cells spontaneously released type I sTNF-R (sTNF-RI) into the culture medium. Hydrogen peroxide accelerated the release of sTNF-RI from the A549 cells time- and dose- dependently. Stimulated release of sTNF-RI by hydrogen peroxide or phorbol myristate acetate (PMA) was inhibited by pretreatment with the intracellular hydroxyl radical scavengers dimethyl sulfoxide and dimethyl thiourea. A synthetic metalloproteinase inhibitor (KB-R8301) inhibited not only spontaneous release of sTNF-RI but also shedding enhanced by hydrogen peroxide and PMA. Preincubation with a protein kinase C inhibitor, calphostin C, downregulated the hydrogen peroxide- or PMA-induced shedding of sTNF-RI. Neither genistein, a tyrosine kinase inhibitor, nor H-89, a protein kinase A inhibitor, inhibited shedding of sTNF-RI by hydrogen peroxide and PMA. Although the surface expression of TNF-R assessed by 125I-TNF specific binding was decreased in the presence of hydrogen peroxide or PMA, TNF-RI mRNA transcript levels remained unchanged. These results show that hydrogen peroxide is involved in the activation of metalloproteinase and protein kinase C responsible for the shedding of sTNF-RI. Accordingly, ROIs may alter TNF action by enhanced shedding of sTNF-RI and reducing its surface receptor expression.
authors.affiliation: The First Department of Internal Medicine, Yamagata University School of Medicine, Yamagata, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hino
authors.forename: H
authors.initials: H
authors.lastname: Nakamura
authors.forename: S
authors.initials: S
authors.lastname: Abe
authors.forename: H
authors.initials: H
authors.lastname: Saito
authors.forename: M
authors.initials: M
authors.lastname: Inage
authors.forename: K
authors.initials: K
authors.lastname: Terashita
authors.forename: S
authors.initials: S
authors.lastname: Kato
authors.forename: H
authors.initials: H
authors.lastname: Tomoike
mesh_terms: D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology; D015870:Gene Expression; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D006877:Hydroxamic Acids / Q000494:pharmacology; D017665:Hydroxyl Radical / Q000378:metabolism; D008168:Lung / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors; D009281:Naphthalenes / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D012995:Solubility; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D006877:Hydroxamic Acids; C423012:KB R8301; D009281:Naphthalenes; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D011494:Protein Kinases; D011493:Protein Kinase C; D008666:Metalloendopeptidases; C058819:calphostin C; D013755:Tetradecanoylphorbol Acetate