Epidemiological Analysis On Respiratory System Injury And DNA Methylation Induced By Coke Oven Emissions

Coke oven emissions(COE)are the main pollutants in the coking production,which contains a large number of Particulate matter(PM)and Polycyclic aromatic hydrocarbons(PAHs).Epidemiological studies showed that exposure to high concentrations of particulate or PAHs is one of the major causes of the respiratory diseases,and cancer caused by COE is classified as a clear occupational tumor.Fine particulate matter(PM2 5)has aerodynamic diameter less than 2.5?m and is easy to enrich toxic and harmful substances on the surfaces,and the adverse effect of PM2.5 on respiratory system is more clearly.PAHs is the main target pollutant in the studies of adverse effect induced by COE exposure,but there is still lack of the analysis of exposure-response relationship between PM2.5 exposure and adverse effect.Occupational COE exposure leads to lung cancer,but there are few studies on the changes of important biological molecules and the early health effect biomarkers in this process.Pulmonary proteins are involved in maintaining the homeostasis of respiratory system including Clara cell protein(CC16),surfactant protein A(SP-A),and surfactant protein D(SP-D).Researchers have been conducting a number of studies on the association of lung injury proteins and pulmonary disease in clinical research.However,there are few studies on the changes of lung injury proteins induced by COE.Exposure to PM and PAHs can lead to an increased risk of multiple diseases,and epigenetic changes may play an important role in the process of carcinogenesis.Genetic damage was hard to reverse,but epigenetic inheritance does not involve changes in DNA sequences which was reversible.DNA methylation is the most widely studied epigenetic modification so far.Researches and our previous studies found that PAHs exposure can cause the aberrant methylation of DNA repair genes and tumor suppressor genes.There are lack of studies on the global DNA methylation induced by PM2.5 and PAHs and studies on the association of global DNA methylation and DNA methyltransferase(DNMTs).We conducted a molecular epidemiological study.Exposure assessment of PM2.5 and PAHs were carried out in several workplaces.We enrolled 558 coke plant workers and 210 control workers in oxygen plant and cold-rolling mill in China.We measured serum high-sensitive C-reactive protein in all subjects.Pulmonary injury was measured by lung function and serum Club cell protein(CC16),surfactant protein A(SP-A),and surfactant protein D(SP-D).Epigenetic modification effects were detected by global DNA methylation level and DNMTs in human white blood cells.1.Respiratory system injury marker with coke oven emissions exposureThe concentrations of PM2.5 were analyzed by weighing method.Ultra-high performance liquid chromatography(UPLC)was used to determine the concentration of 16 PAHs.An ultra-high performance liquid chromatography-mass spectrometry(UPLC-MS/MS)method was used to measure the urinary 1-OHP.Serum high-sensitivity C-reactive protein(hs-CRP)was measured by an automatic biochemistry analyzer.Serum CC16,SP-A and SP-D were measured by sandwich ELISA.The lung function tests were conducted by a pulmonologist using a fixed electronic spirometer.Serum CC16 levels reduced with the increasing occupational exposure history of COE.An IQR(121.98 ?g/m3)increased of PM2.5 was associated with 5.24%decrease(P=0.004)in serum CC16.An IQR(3.81 ?g/m3)increased of ?PAHs was associated with 5.69%decrease(P=0.027)in serum CC16.Serum CC16 was also identified with each IQR increase in urinary 1-OHP concentration(1.06 ?mol/mol creatinine)associated with 4.67%decrease in serum CC16(P=0.041).Furthermore an IQR decrease in serum CC16(3.95 ng/mL)was associated with 0.87%decrease in FEV1/FVC in the male participants(P = 0.045).2.DNA methylation induced by coke oven emissions exposureGlobal DNA methylation(5-mC%)was measured by methylated DNA quantification kit.Quantitative analysis of DNMTs was measured by real-time quantitative PCR(RT-qPCR)method.Serum folic acid and vitamin B12 levels were also examined.Global DNA methylation(5-mC%)reduced with the increasing occupational exposure history of COE.An IQR(121.98 ?g/m3)increased of PM2.5 was associated with 5.78%decrease(P<0.001)in Global DNA methylation(5-mC%).An IQR(3.81 ?g/m3)increased of ?PAHs was associated with 6.09%decrease(P=0.007)in Global DNA methylation(5-mC%).Urinary 1-OHP was negatively correlated with Global DNA methylation(5-mC%)(?=-0.025,P<0.001).The association of ambient environmental PM2.5 with DNMT1 and DNMT3A were not found.An IQR(3.81 ?g/m3)increased of ?PAHs was associated with 13.25%decrease(P=0.027)in DNMT3A.No significant correlation was found between urinary 1-OHP with DNMT1 and DNMT3A.Regression analysis showed that global DNA methylation(5-mC%)was positively correlated with DNMT1 and DNMT3A.Mediation model analyzed 5.95%of the effects of PAHs exposure on global DNA methylation mediated through changes in DNMT3 A.3.Association of lung injury and DNA methylation markers induced by coke oven exposureThe correlation between lung injury markers(serum CC16,SP-A,SP-D),lung function and DNA methylation(5-mC%,DNMT1,DNMT3A)was analyzed by correlation analysis and multiple linear regression analysis.Serum CC16 concentration was found to be positively correlated with DNMT1(r = 0.075,P = 0.040).After layered by age,there was a significant positive correlation between serum CC16 and DNMT1 and DNMT3A in patients younger than 45 years.Mediation of DNA methylation in lung injury induced by COE was not found.Conclusions1.Reduced serum Club cell protein as an early pulmonary injury marker for COE exposure.2.COE exposure can cause the reduction of DNA methylation.And the reduction of DNMT3 A is an important factor in the decrease of global DNA methylation.DNMT3 A is not the key factor mediating lung injury caused by COE.