Effects of Disease Status on Variability in Oxidative Stress Responses to Traffic Exhaust Exposure: Oxford Street Ⅱ Study

摘要

Subjects with different susceptibilities show a considerable amount of variability in responses to pollutant exposure, but few studies have attempted to assess the sources of inter-personal variability. As part of an ongoing study of cardio-respiratory effects of diesel-traffic exposure in persons with chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD), or free of these diseases (40 subject per group), we compared biomarker levels of oxidative stress in response to real-life diesel traffic exposure by disease status. To date, we have completed analysis on 24 healthy volunteers, 22 COPD and 9 IHD patients. We are examining intra-subject differences in response to a two-hour walk on a city street with high diesel-traffic density compared to a walk in a nearby traffic-free park. Urine samples were collected from each participant 2 hours before and 24 hours after the walk. Two biomarkers, i.e. malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), were analyzed using HPLC-fluorescence/ECD. After the walk on the diesel-traffic street, concentrations of 8-OHdG (mean ± standard deviation) increased by 29±74%, 99+155%, and 121±275% for healthy, COPD, and IHD subjects, and concentrations of MDA increased by 37±94%, 109±245%, and 97±265% for the three groups of subjects. In contrast, after the walk in the traffic-free park, concentrations of 8-OHdG increased by 28±112%, 68+115%, and 41 ±117% for healthy, COPD, and IHD subjects, and concentrations of MDA increased by 31 ±151%, 54±121%, and 35+98% for the three groups. Subjects with COPD and IHD show higher biomarker responses to diesel-traffic exposure than to traffic-free exposure, while healthy subjects showed comparable biomarker responses. Preliminary results indicate that individuals with COPD and IHD had higher magnitudes of changes in oxidative stress following traffic exposure. The findings will help to improve risk assessment by considering the effect of disease susceptibility factors.