Increased concentrations of glutathione in induced sputum of patients with mild or moderate allergic asthma

Abstract

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. To quantify oxidative stress in sputum of asthmatic patients compared with healthy subjects. 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. 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). 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.