Activities of Antioxidant Enzymes in Relation to Oxidative and Nitrosative Challenges in Childhood Asthma

Background. This study aimed to investigate the relationship between antioxidant enzyme activities, extent of airway inflammation, and systemic oxidative stress in children suffering from atopic asthma. Methods. A total of 35 asthmatic (AG) and 21 healthy children (CG) participated in this study. The volume of fractionated exhaled NO (FENO) was measured with the NIOX test system. The activities of the erythrocyte antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), and the total antioxidant capacity (TAC) were determined photometrically. Plasma interleukin (IL)-6 was measured using ELISA; malondialdehyde (MDA) levels were analyzed using HPLC. Results. Compared to healthy controls, asthmatic children exhaled a significantly (p < .001) higher mean volume of FENO, had significantly reduced plasma concentrations of TAC (p = .006), and significantly enhanced levels of MDA (p < .001) and IL-6 (p = .012). SOD (p = .027), CAT (p < .001), and GSH-Px (p = .005) were significantly less active in the asthma group and significantly negatively associated with FENO (SOD/FENO : p = .017; CAT/FENO : p = .008; GSH-Px/FENO : p = .001); the oxidative stress marker MDA showed such correlations in both investigated groups (SOD/MDA: AG: p = .001, CG: p = .381; CAT/MDA: AG: p = .003, CG: p = .020; GSH-Px/MDA: AG:p = .006, CG: p = .011). Furthermore, there was a significant (p < .01) positive correlation between MDA/FENO and MDA/IL-6 observed in both groups. Conclusions. These results indicate that inflammation of the bronchial tree, reflected by increased NO formation in the airways and enhanced systemic oxidative stress, is related to an alteration of antioxidant enzyme activities in childhood asthma. Modulating the activity of antioxidant enzymes may therefore have beneficial effects on pulmonary and systemic antioxidant defense mechanisms and could reduce airway inflammation and oxidative stress in asthmatics.