Oxidative status in the lungs associated with tobacco smoke exposure

Abstract

BACKGROUND: Oxidative stress has a critical role in inflammatory responce against tobacco smoke (TS). Testing exhaled breath condensate (EBC) samples is one of the methods used for assessment of airway inflammation caused by TS. We aimed to investigate oxidative stress in the lungs associated with TS and to evaluate the effect of this stress with pulmonary function tests (PFTs). METHODS: We included 69 subjects as three groups into the study (Group I; 26 smokers, Group II; 21 passive smokers, Group III; 22 non-smokers without TS exposure). Levels of malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), nitrite/nitrate [index of nitric oxide (NO) production], vitamin C, superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were measured in EBC samples collected using a condenser and PFTs were performed. RESULTS: The levels of MDA, 8-OHdG, SOD and GSH-Px were higher in smokers. NO levels gradually increased from Group I to Group III. MDA levels were lower in Group III than Group II. The levels of vitamin C were similar in all groups. We determined negative correlation between 8-OHdG levels and forced expiratory volume in one second (FEV₁), and maximum mean expiratory flow (MMEF), and a positive correlation between SOD levels and FEV₁. CONCLUSIONS: TS exposure affected the balance between oxidative stress and antioxidant capacity of lungs. Preventing environmental TS exposure might decrease oxidative damage. Increased levels of 8-OHdG and SOD levels could be assessed as an early sign of airway damage.