The effect of cigarette smoking on the oxidant-antioxidant imbalance in patients with chronic obstructive pulmonary disease

Background Predisposing factors for chronic obstructive pulmonary disease (COPD) comprise endogenous genetic factors and exogenous factors such as positive and negative smoking, air pollution, inhalation of dust, and work-related chemicals. Because only a small percentage of smokers develop COPD, it is thought to arise as an outcome of environmental harm and a host's response system, which boosts the tendency of the disease to arise. Objective To clarify the effect of smoking on the level of oxidant-antioxidant in patients with COPD. Patients and methods Thirty patients with COPD (20 smokers and 10 nonsmokers) and 40 healthy individuals (18 smokers and 22 nonsmokers) participated in this study. The investigations included measurement of malondialdehyde (MDA), superoxide dismutase (SOD) activity, catalase (CAT) activity, glutathione peroxidase (GPx), glutathione reductase (GR), vitamin C, and glutathione (GSH) content. Results SOD, CAT, GPx, GSH, GR, and vitamin C were significant lower (P<0.0001) among patients with COPD (smokers and nonsmokers) than in the control group, whereas the MDA levels were elevated (P<0.0001) in patients with COPD (smokers and nonsmokers) when compared with the control group. Moreover, the values of SOD, GSH, and GPx were significantly lower (P<0.001) in smokers with COPD as compared with nonsmokers with COPD. Finally, there was no significant difference in the level of MDA between patients with COPD (smokers and nonsmokers). Conclusion There is a significant reduction in the level of some antioxidants (SOD, GSH, and GPx) in smokers with COPD compared with nonsmokers with COPD, but other antioxidants (CAT, GR, and vitamin C) did not change significantly, whereas the oxidant levels (i.e., MDA) were relatively convergent in patients with COPD (smokers and nonsmokers). This, in turn, points to the modest role of smoking in the causation of oxidant-antioxidant imbalance in this disease.