Relationship Between Maternal PAHs Exposure On DNA Methylation And BPDE-DNA Adducts In Cord Blood

Objective:To investigate the body burdens of polycyclic aromatic hydrocarbons (PAHs) of pregnant women and to explore the influencing factors related to PAHs exposures. To discuss the relationship between BaP levels and BPDE-DNA adducts in cord blood. To explore the effect on the global DNA methylation and specific gene methylation in cord blood caused by prenatal exposure. To research the relationship between prenatal PAHs exposure on BPDE-DNA adducts and DNA methylation in cord blood.Methods:1. Questionnaire investigation on random selected and voluntarily participating pregnant women was conducted and maternal blood and cord blood was collected.2.216pregnant women from one hospital were investigated and questionnaire survey was conducted to obtain individual behavior and life style during the period of July to December2012. PAHs levels in205pregnant women serum samples was detected by high-performance liquid chromatography(HPLC).3. Capillary electrophoresis-laser induced nuorescence immunoassay method was used to determine the concentrations of BPDE-DNA adducts.4. The globle DNA methylation was scanning by LC-MS/MS. And simple univariate statistics analysis and multivariate linear stepwise regression was also conducted to select the important factors of the change on globle DNA methylation.5. The gene-specific methylation level was quantified by pyrosequencing in cord blood. And T-test and multivariate linear stepwise regression was also carried to select the important factors of the change on gene-specific methylation.6. Relationship between prenatal PAHs exposure on BPDE-DNA adducts and DNA methylation in cord blood was analyzed by T-test and multivariate linear stepwise regression.Results:1. The detection rate of Pyr in205pregnant women serum samples was still the highest which was98.9%and95.2%. and the detection rate of BaP in205pregnant women serum samples was47.3%, and the mean BaP concentration was0.035ng/ml (P25:0.02,P75:0.07) ng/ml. The concentration of AnT、Pyr、BaA、BkF、BaP and BghiP in cord serum is statistically higher than those in paired maternal (p=0.002)2. There was much higher BaP concentration in pregnant women who lived nearby the traffic artery.3. The detection rate of BPDE-DNA adducts in cord blood was86.1%. But the level of PAH-DNA adducts detected were not significantly associated with BaP either in cord or maternal serum.4. According to the results of LC-MS/MS analysis and T-test, various kinds and levels of PAHs has individual effect on global DNA methylation. Statistics of multivariate linear stepwise regression reveals that the concentration of BaP and BkF in cord blood serum was an important factor on the global methylation.5. According to the results of pyrosequencing in cord blood analysis and statistics of T-test, both the gender of newborns and folic acid supplement during pregnancy can affect the global methylation changes. The concentration of BaP could negatively influence the gene-specific methylation of CpG site, but BbF and BkF has the opposite result. Multivariate linear stepwise regression reveals that several PAHs can be fitted the model, that is, PAHs exposure in gestion period is the most important factor for the gene-specific site methylation of P16and P53.6. T-test shows that the levels of DNA methylation are associated with the presence of detectable BPDE-DNA adducts. Both the positive association relationship between global DNA methylation and the presence of BPDE-DNA adducts and the negative association between site-specific methylation and adducts are revealed after multivariate linear stepwise regression.7. The level of DNA methylation was more easily detected than BPDE-DNA adducts for PAHs exposure.Conclusions:1. Several kinds of PAHs can be detected in general pregnant woman of the study. Living nearby the traffic artery is the main factor among all of the surveying factors and outdoor air pollution maybe play an important role in prenatal PAHs exposure.2. PAHs can be detected in maternal and umbilical serum, and body levels of PAHs in maternal serum are related with those in body of fetus. BaP can be regarded as the representative of the total PAHs in evaluating the level of PAHs exposure.3. DNA damage in the developing through the transplacental exposure to PAHs from maternal fetus was also confirmed.4. Prenatal exposure to PAHs can change the global DNA methylation and different kinds of PAHs have different effects on global DNA methylation which means they may have their individual mechanisms of adverse effects.5. Prenatal exposure to PAHs can also ater the site-specific methylation of P53and P16, which maybe result in other gene damage and increase the risk of future diseases for the baby.6. Global DNA methylation and site-specific methylation of P16are related with the presenceof detectable BPDE-DNA adducts and there maybe interactions either inhibiting or accelerating between them.