Effect And Mechanism Of Air Pollution Particulate Matter PM2.5on Apoptosis In Human Bronchial Epithelial Cells

Objective In recent years, with the rapid development of economy and society in China, industrialization and urbanization speeds up unceasingly, the emission of pollutants increase continuously, thus the air pollution become more and more serious. Now there are four serious haze pollution areas: Huanghuaihai area, Changjiang valley, Sichuan basin and Pearl river Delta. And Guangzhou as the economic and cultural center of Pearl river Delta which with the most rapid development, it’s air pollution problem is more critical, because a large number of Internal Immigrants move in, the number of traffic implement and construction of energy supply facilities have grown rapidly. According to the statistical results provided by the weather department, both of the haze weather duration dates and the total number of haze weather influenced days across the whole year were increased year by year in Guangzhou. Of late years many epidemiological investigations about the particle-induced health effects could be found in domestic and foreign academic magazines. The results have shown that air pollution matters are associated with the increase of respiratory mortality and morbidity. Air pollution matters pose a dangerous health hazard. But now most study of air pollution matters on health are component analysis and epidemiological investigations, In vitro experimental study on mechanism is few at home and abroad. So in order to explore the effect of air pollution particulate matters PM2.5on respiratory system and it’s possible mechanism, we collect Guangzhou haze particulate matters PM2.5, study the effect and mechanism on apoptosis in human bronchial epithelial cells.Materials and Methods Guangzhou city was chosen as the representative sampling site which was influenced by the haze weather in the Pearl River Delta. The sampling time was from July2008(summer) to December(winter). According to the weather reports, the environmental high-volume samplers were used to collect the PM2.5fraction of the right days that satisfy haze definition (visibility in atmosphere below10kilometers and air moisture less than90%). Haze sample filter membranes were deal by ultrasonic processing and the wet scratch method. Then particulate matters were gotten after the vacuum freeze-drying. The human bronchial epithelial cells (16-HBE) were exposed to8,16,32,64,128μg/ml haze particulate matter PM2.5from Guangzhou. After24,48and72h of incubation, the cell survival rate, apoptosis ratio, DNA damage and oxidative damage were respectively determined by MTT, Annexin V/PI apoptosis assay, SCGE and8-OHdG(human) ELlSA kit.Results1、With the increase in the concentration and the time prolongation of PM2.5, the cell survival rate was decreased. After24,48and72h treated, compared with the negative control, the cell survival rates of64,128μg/mL groups decreased significantly (P<0.05), Compared with the24h group, the cell survival rates of all treated groups in72h decreased significantly (P<0.05). 2、The cell total apoptotic rate increased with the increase in the concentration and the time prolongation of PM2.5. After24h treated, compared with the negative control, the cell total apoptotic rates of64,128μg/mL groups increased significantly (P<0.05), After48and72h treated, compared with the negative control, the cell total apoptotic rates of32,64,128μg/mL groups increased significantly (P<0.05). Compared with the24h group, the cell total apoptotic rates of72h increased significantly except8μg/mL group (P<0.05).3、DNA damage increased with the increase in the concentration and the time prolongation of PM2.5. After24,48and72h treated, compared with the negative control, the DNA Olive tail moment of all groups increased significantly (P<0.05). Compared with the24h group, the DNA Olive tail moment of all groups in48and72h increased significantly (P<0.05).4、Oxidative damage increased when the concentration and time of PM2.5exposed increased. After24,48and72h treated, compared with the negative control, the concentration of8-Hydroxy-2’-deoxyguanosine of64,128μg/mL groups increased significantly (P<0.05). Compared with the24h group, the concentration of8-Hydroxy-2’-deoxyguanosine of128μg/mL group in72h increased significantly (P<0.05).5、Not only there was positive correlation between cell total apoptotic rate and DNA damage (r24h=0.960, r48h=0.973, r72h=0.981, P<0.05), but also there was positive correlation between cell total apoptotic rate and the concentration of8-Hydroxy-2’-deoxyguanosine (r24h=0.936, r48h=0.957, r72h=0.885, P<0.05), and DNA damage was significantly correlated with the concentration of8-Hydroxy-2’-deoxyguanosine (r24h=0.969, r48h=0.893, r72h=0.940, P<0.05).Conclusion1、Air pollution particulate matter PM2.5have cytotoxic effect on human bronchial epithelial cells (16-HBE), it can induce16-HBE cell apoptosis.2、Air pollution particulate matter PM2.5have genotoxic effect on human bronchial epithelial cells (16-HBE), it can induce human bronchial epithelial cells (16-HBE) DNA damage.3、Air pollution particulate matter PM2.5can induce16-HBE cell oxidative damage.4、It can be concluded from above results that Air pollution particulate matter PM2.5can produce reactive oxygen species, leads to the imbalance between the ability of oxidation and the ability of antioxidation, finally bring into DNA oxidative damage, and then DNA strand breaks, induce cell apoptosis. Oxidative damage is one of the mechanisms of Air pollution particulate matter PM2.5induce respiratory tract injury.