Background: Oxidative stress is involved in the pathogenesis of allergic inflammatory diseases, such as rhinitis and asthma. Glutathione is a vital intracellular and extracellular protective pulmonary antioxidant. It plays a key role in regulating oxidant-induced lung epithelial cell function and also in the control of proinflammatory processes.
Objective: To quantify oxidative stress in sputum of asthmatic patients compared with healthy subjects.
Methods: We quantified induced sputum supernatant concentrations of total and oxidized glutathione in 20 patients with mild asthma without inhaled corticosteroid treatment, 19 patients with moderate-persistent asthma treated with inhaled corticosteroids (median dose, 900 microg/d of beclomethasone equivalent), and 15 healthy, nonatopic, nonsmoking subjects.
Results: Total glutathione levels were significantly increased in mild and persistent asthma compared with healthy subjects [geometric mean (95% confidence interval), 9.2 microM (7.1-12 microM) and 8.7 microM (5.9-12.5 microM) vs 4 microM (2.7-6 microM); P = .039 and .042, respectively]. In contrast, there were no differences in total and oxidized glutathione levels between steroid-naïve and steroid-treated asthmatic patients (P > .20 for all comparisons). Persistent, steroid-treated asthmatic patients had higher sputum counts of neutrophils than steroid-naïve asthmatic patients [geometric mean (95% confidence interval), 35.6% (28.2%-42.7%) vs 17.7% (11.7%-27.1%), P = .04]. There was a positive correlation of total glutathione with sputum total cells (rho = 0.32, P = .02).
Conclusions: Total glutathione is increased in induced sputum of patients with mild and moderate asthma. These data underline the contribution of oxidative stress to the pathogenesis of allergic asthmatic inflammation.