title: Antioxidant properties of cystic fibrosis sputum.
abstract: Oxidative stress is a likely contributor to the pathogenesis of cystic fibrosis (CF) lung disease. However, hydrogen peroxide (H(2)O(2)), a physiological oxidant, is not elevated in CF exhalates. H(2)O(2) may be neutralized by antioxidants in CF airway secretions. The H(2)O(2)-detoxifying capacity of CF airway secretions, obtained via sputum induction, was studied in an in vitro H(2)O(2) cytotoxicity model. 16HBE14o- cells were exposed to H(2)O(2) in culture medium containing either 0 or 10% fetal bovine serum (FBS) or 10% CF sputum supernatant (extracted without use of dithiothreitol). The efficiency of H(2)O(2) neutralization was estimated by measuring intracellular oxidant levels (dihydrorhodamine 123) after 2 h and cell viability (propidium iodide) after 24 h of H(2)O(2) exposure. Furthermore, the presence of reduced thiols (DTNB assay) and reduced glutathione (recycling assay) in CF sputum samples was evaluated. CF sputum extracts completely prevented intracellular oxidant accumulation seen in cells incubated with H(2)O(2) in both control media (i.e., 0 or 10% FBS). Furthermore, CF sputum abolished cell death in 16HBE14o- cells exposed to up to 1 mM H(2)O(2). In contrast, there was 100% cytotoxicity in cells exposed to 600 microM H(2)O(2) in both control media. The H(2)O(2)-detoxifying potential of CF sputum was sustained after catalase and heme peroxidases were inactivated by sodium azide, which does not affect glutathione peroxidase. In addition, reduced protein thiols were found in abundance in CF sputum. In conclusion, CF sputum is capable to neutralize H(2)O(2) and abundant reduced thiols and/or glutathione peroxidase are fully sufficient to detoxify H(2)O(2).
authors.affiliation: Divisiohn of Pulmonary Medicine, Hospital of Johann Wolfgang Goethe University, Frankfurt/Main, Germany.
authors.forename: Nurlan
authors.initials: N
authors.lastname: Dauletbaev
authors.forename: Jens
authors.initials: J
authors.lastname: Rickmann
authors.forename: Klaus
authors.initials: K
authors.lastname: Viel
authors.forename: Holger
authors.initials: H
authors.lastname: Diegel
authors.forename: Christian
authors.initials: C
authors.lastname: von Mallinckrodt
authors.forename: Jürgen
authors.initials: J
authors.lastname: Stein
authors.forename: Thomas O F
authors.initials: TO
authors.lastname: Wagner
authors.forename: Joachim
authors.initials: J
authors.lastname: Bargon
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000037:antagonists & inhibitors / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D003550:Cystic Fibrosis / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology; D010544:Peroxidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020545:Respiratory Mucosa / Q000166:cytology / Q000378:metabolism; D019810:Sodium Azide / Q000494:pharmacology; D013183:Sputum / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D016877:Oxidants; D019810:Sodium Azide; D006861:Hydrogen Peroxide; D010544:Peroxidases; D002374:Catalase