DNA damage and repair capacity in lymphocyte of chronic obstructive pulmonary diseases patients during physical exercise with oxygen supplementation

Background: We hypothesized that the use of oxygen supplementation during aerobic exercise induces less DNA damage than exercise alone. The aim of this study is to assess the level of DNA damage induced by physical exercise with and without oxygen supplementation in chronic obstructive pulmonary diseases (COPD) patients. Methods: Peripheral blood was collected before and after aerobic exercise in two conditions: (I) aerobic exercise without oxygen supplementation (AE group) and (II) with oxygen supplementation (AE-O2 group). Lymphocytes were collected to perform the alkaline version of the Comet Assay. To assess the susceptibility to exogenous DNA damage, the lymphocytes were treated with methyl methanesulphonate (MMS) for 1-h or 3-h. After 3-h treatment, the percentage of residual damage was calculated assuming the value of 1-h MMS treatment as 100%. Results: AE group showed lower induced damage (1 h of MMS treatment) and consequently less DNA repair compared to AE-O2 group. AE-O2 group showed an increase in the induced DNA damage (1 h of MMS treatment) and an increased DNA repair capacity. Within the AE-O2 group, in the post-exercise situation the induced DNA damage after 1 h of MMS treatment was higher (p = 0.01) than in the pre-exercise. Conclusion: COPD patients who performed physical exercise associated with oxygen supplementation had a better response to DNA damage induced by MMS and a better DNA repair when compared to the condition of physical exercise without oxygen supplementation.Trial registration: UNISC N374.298. Registered 04 JUN 2013 (retrospectively registered).