GSTM1 and GSTP1 and respiratory health in asthmatic children exposed to ozone

Acute exposure to ozone has been related to a wide spectrum of health effects in susceptible individuals. Genetic factors may influence interindividual variation in ozone response. The current authors investigated the relationships between common polymorphisms in two genes involved in response to oxidative stress, i.e. glutathione S-transferases M1 (GSTM1) and P1 (GSTP1), and both respiratory symptoms and lung function in response to ozone among childhood asthmatics. A total of 151 asthmatic children, who were participants in a randomised controlled trial of antioxidant vitamin supplementation in Mexico City, were studied. Children were genotyped using PCR methods and followed from October 1998-April 2000. Increases in reported breathing difficulty were associated with ozone exposure in children with GSTM1 null (8%, 95% confidence interval (CI) 1-15%, per 20-ppb increase in 1-h maximum daily average over 7 days) or GSTP1 Valine/Valine (Val/Val) genotypes (14%, 95% CI 5-25%). In children with both GSTM1 null and GSTP1 Val/Val genotypes, the increase in breathing difficulty associated with a 20-ppb increase in ozone exposure was even greater (21%, 95% CI 5-39%). GSTP1 genotypes were not significantly associated with ozone-related lung function changes. In conclusion, asthmatic children with glutathione S-transferase M1 null and glutathione S-transferase P1 Valine/Valine genotypes appear more susceptible to developing respiratory symptoms related to ozone exposure.

Antioxidant supplementation and nasal inflammatory responses among young asthmatics exposed to high levels of ozone

The inflammatory response to ozone in atopic asthma suggests that soluble mediators of inflammation are released in response to oxidant stress. Antioxidants may alleviate additional oxidative stress associated with photochemical oxidant pollution. This study investigates the impact of antioxidant supplementation on the nasal inflammatory response to ozone exposure in atopic asthmatic children. We conducted a randomized trial using a double-blinded design. Children with asthma (n = 117), residents of Mexico City, were given randomly a daily supplement of vitamins (50 mg/day of vitamin E and 250 mg/day of vitamin C) or placebo. Nasal lavages were performed three times during the 4-month follow-up and analysed for content of interleukin-6 (IL-6), IL-8, uric acid and glutathione (GSx). IL-6 levels in the nasal lavage were increased significantly in the placebo group after ozone exposure while no increase was observed in the supplement group. The difference in response to ozone exposure between the two groups was significant (P = 0.02). Results were similar for IL-8, but with no significant difference between the groups (P = 0.12). GSx decreased significantly in both groups. Uric acid decreased slightly in the placebo group. Our data suggest that vitamin C and E supplementation above the minimum dietary requirement in asthmatic children with a low intake of vitamin E might provide some protection against the nasal acute inflammatory response to ozone.