Study on the Effect of Air Pollutant Exposure on Synthesis of IGE in Asthmatic Children

This dissertation, "Study on the Effect of Air Pollutant Exposure on Synthesis of IgE in Asthmatic Children" by Xia, Lin, 林夏, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Objective Large quantities of epidemiological studies manifest that indoor and outdoor air pollutants may trigger and aggravate asthma symptoms, whose mechanism, however, has not been completely made clear yet. As shown by the result of the experiment in which in-vitro cells and animals are exposed to high-density air pollution, the triggering effect of air pollution on asthma is associated with inflammatory reaction, IgE expression and regulation pathways. However, there is a lack of evidence from population studies to support that association. This study plans to conduct continuous monitoring over indoor and outdoor air pollutants facing the asthmatic children from Beijing with a view to carry out an overall assessment of their exposure to air pollutants. Meanwhile, biomarkers which are directly reflecting airway inflammation as well as the signal molecules which are related to IgE expression and regulation are monitored. The next step is to establish an exposure-effect relationship to explore the trigger effect of air pollutants on childhood asthma. Methods 1. Questionnaires were used to collect general information (including age, drug use, indoor home decoration, passive smoking, diet during the study, indoor mildew, allergic history, history of diseases and family heredity history) in 60 asthmatic children (males, Han nationality, aged 5 to 14 years)from Beijing who were recruited into this study. 2. A comprehensive evaluation was conducted on their exposure levels of air pollutants by continuous monitoring of indoor PM2.5, black carbon, benzene, toluene, xylene and formaldehyde in their houses and collecting monitoring data with respect to PM2.5, PM10, NO2and SO2at air quality monitoring sites near their houses. Benzene, toluene and xylene were measured by two-stage thermal desorption-gas chromatography (GC), formaldehyde by AHMT spectrophotometry, mass concentration of PM2.5by gravimetric method, black carbon in PM2.5by multi-wavelength absorption spectroscopy. The concentration data of ambient outdoor air pollutants were available from the real-time air quality publishing platform of Beijing Municipal Environmental Monitoring Center. 3. Exhaled FeNO of asthmatic children were taken as biomarkers reflecting their airway inflammation. FeNO was measured by electrochemical method (off-line monitoring). 4. Trigger effect of air pollution on IgE signaling pathway of asthmatic children was investigated by determining signal molecules of two signaling pathways related to IgE expression and regulation in peripheral serum. Signal molecules were determined by ELISA. 5. Confounding factors were controlled by stratification analysis and multiple linear regression model, and a comprehensive analysis was conducted of the triggering effect of air pollution on children asthma. Results 1. During the research, as for subjects, concentrations of indoor PM2.5, BC, formaldehyde, benzene, toluene, m-, p-and o-xylenes were 55.329.9 μg/m3, 3.81.4 μg/m3,62.242.7 μg/m3, 13.115.9 μg/m3, 18.716.7 μg/m3, 7.97.9 μg/m3and 3.15.0 μg/m3, respectively. The7-day weighted average concentrations of outdoor PM2.5, PM10, SO2and NO2were 101.387.6μg/m3, 152.888.4μg/m3, 48.639.8 μg/m3and 63.127.7μg/m3, respectively. There was a significant correlation between 7-day weighted average concentrations of indoor and outdoor PM2.5 simultaneo