Ozone exposure, antioxidant genes, and lung function in an elderly cohort: VA normative aging study

Background: Ozone (O-3) exposure is known to cause oxidative stress. This study investigated the acute effects of O-3 on lung function in the elderly, a suspected risk group. It then investigated whether genetic polymorphisms of antioxidant genes (heme oxygenase-1 (HMOX1) and glutathione S-transferase pi (GSTP1)) modified these associations. Methods: 1100 elderly men from the Normative Aging Study were examined whose lung function (forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1)) was measured every 3 years from 1995 to 2005. The study genotyped the GSTP1 Ile105Val and Ala114Val polymorphisms and the (GT) n repeat polymorphism in the HMOX1 promoter, classifying repeats as short (n<25) or long (n >= 25). Ambient O-3 was measured continuously at locations in the Greater Boston area. Mixed linear models were used, adjusting for known confounders. Results: A 15 ppb increase in O-3 during the previous 48 h was associated with a 1.25% decrease in FEV1 (95% CI: -1.96% to -0.54%). This estimated effect was worsened with either the presence of a long (GT) n repeat in HMOX1 (-1.38%, 95% CI: -2.11% to -0.65%) or the presence of an allele coding for Val105 in GSTP1 (-1.69%, 95% CI: -2.63% to -0.75%). A stronger estimated effect of O-3 on FEV1 was found in subjects carrying both the GSTP1 105Val variant and the HMOX1 long (GT) n repeat (-1.94%, 95% CI: -2.89% to -0.98%). Similar associations were also found between FVC and O-3 exposure. Conclusions: Our results suggest that O-3 has an acute effect on lung function in the elderly, and the effects may be modified by the presence of specific polymorphisms in antioxidant genes.