Oxidative stress and antioxidant enzyme activity in South Indian male smokers with chronic obstructive pulmonary disease

Abstract

Oxidative stress resulting from tobacco smoking has been suggested to play a role in the pathogenesis of chronic obstructive pulmonary disease (COPD). The aim of the present study was to evaluate the oxidant and antioxidant levels in smokers with and without COPD. Two hundred thirty-six patients with COPD and 150 smokers with no respiratory problems were selected. COPD diagnosis and staging was done based on the Global Initiative for Chronic Obstructive Lung Disease criteria. Plasma malondialdehyde (MDA) and erythrocyte glutathione (GSH) concentrations and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione-s-transferase (GST) activities were assessed. COPD patients had higher levels of MDA and lower levels of antioxidants when compared with controls (P < 0.01). Analysis of variance revealed increase in MDA (P < 0.05) and decrease in CAT activity (P < 0.01) and GSH (P < 0.05) level with the progression of the disease. In patients, lung function positively correlated with CAT and SOD activities and negatively correlated with MDA levels (P < 0.01). Smoking history showed negative relation with forced expiratory volume in 1 s (FEV1 )/forced vital capacity (P < 0.05) and positive correlation with CAT activity (P < 0.01). MDA levels negatively correlated with SOD (r = -0.239; P < 0.01). In controls, MDA levels showed significant positive correlation with FEV1 and GPx (P < 0.05) and negative correlation with GSH (P < 0.01). Logistic regression showed association of higher MDA levels with increased risk and higher levels of CAT and GSH with decreased risk of progressing in the disease (odds ratio = 2.938, 2.538, 7.860). Our study demonstrates that there is an oxidant antioxidant imbalance in COPD patients and suggests the importance of GPx in maintaining lung function.