DNA and fatty acids oxidative stress in respiratory diseases: Preliminary results from the GEIRD study

Among the determinants of respiratory diseases, emphasis has recently been placed on oxidative stress, but its role on the occurrence of the respiratory diseases is only partially known. The aim of this study is to investigate the oxidative stress levels in people with respiratory diseases and controls. 8-OHdG, a DNA oxidation product, and 8-isoprostane, a lipid oxidation product, were measured in spot-urine samples collected in the frame of Genes Environment Interactions in Respiratory Diseases (GEIRD) study, a nested multi-case control survey. Controls and cases of COPD, current asthma, past asthma, non-allergic rhinitis, allergic rhinitis and other respiratory conditions (n= 239, 19, 122, 70, 58, 45 and 76 respectively) were analysed to test differences in levels of urinary creatinine-corrected 8-OHdG and 8-isoprostane, using quantile regression models adjusting for age, gender, smoking habits, BMI and other potential confounders. Adjusted 8-OHdG median concentrations were significantly higher in allergic rhinitis (4.7ng/mg, 95%CI 3.8;5.6), current asthma (4.3ng/mg, 95%CI 3.7;4.9) and COPD cases (5.4ng/mg, 95%CI 3.8;7.1) than in controls (3.3ng/mg, 95%CI 2.8;3.8). 8-isoprostane median levels were higher, even if not significantly different, in subjects with respiratory diseases (range 0.57-0.69ng/mg) than in controls (0.51ng/mg). While 8-isoprostane seems to be implied to a minor extent in respiratory illnesses, 8-OHdG has a significant association in COPD, asthma and allergic rhinitis.