| Coke oven emissions(COEs) can cause occupational lung cancer. In China, the biological exposure limit of COEs hasn’t been established. In recent years, studies about telomere DNA damage have been widely used in the field of occupational health, and it is necessary to further explore the value of it as a marker of effect, and explore the role of genes related to telomere damage.Objective1. To explore the values of accumulative exposed dose of COEs, concentrations of urinary metabolites and the biomarkers of telomere damage. The dose-response relationship and benchmark dose(BMD) were explored to provide the basis to revision of occupational standard.2. To explore the effect of related susceptible biomarkers and factors on telomere damage, by determining polymorphisms of telomere pathway genes, cell cycle-regulation genes and metabolic enzyme genes, and the expression of related genes.Methods1. Subject544 workers in coke plant were recruited in exposure group, and their working years are more than 1 year. 238 non-occupational exousure and healthy people were enrolled in the control group. The questionnaire survey included: name, gender, date of birth, smoke, alcohol and occupational history.2. Methods2.1 Exposure detection: the concentrations of COEs in workshop were detected and accumulated exposure doses were estimated. The concentrations of1-hydroxypyrene(1-OHPYR), 3-hydroxyphenanthrene(3-OHPHE) and2-hydroxynathalene(2-OHNAP) in urine of shift end were detected using high performance liquid chromatography(HPLC).2.2 Detection of effective biomarkers: venous blood was extracted in all subjects;quantitative polymerase chain reaction(q PCR) method was used to detect the telomere length of DNA in the whole white blood cell. Malondialdehyde(MDA),hydrogen peroxide(H2O2), catalase(CAT) and total antioxidant capacity(T-AOC) in serum were detected by agent kits.2.3 Gene detection: Polymerase chain reaction(PCR) and restriction fragment length polymorphisms(RFLP) method were used to detect the genotypes of telomere pathway genes, cell cycle-regulation genes and metabolic enzyme genes. q PCR method was used to detect the m RNA expressions of related genes.3. Statistical analysisSPSS21.0 software was used for data analysis. Non-normal distribution data were described in median(P25, P75), rank sum test was used to compare the differences among the groups; chi-square test was used to compare the differences of classification variables. Quartile regression of Stata 13.0 software was used to analyze the influence factors of telomere length. Inspection standard α=0.05.BMDS 2.6.0.1 from EPA was used to analyze benchmark dose.Results1. Investigation of coke oven workers’ occupational exposureCoal car drivers, pushing coke drivers, oven door labors in coke side, riser labors and oven repair labors who exposed the time weighted average concentration(TWA)of COEs exceeded the occupational exposure limits. The accumulated exposure dose of workers in exposure group is 1.12(0.34, 2.14) mg/m3 per year. The concentrations of urine 1-OHPYR and 3-OHPHE respectively are 83.80(40.29, 163.55) pg/μg creatinine and 18.20(9.99, 35.63) pg/μg creatinine, and the major influencing factors are gender, age, smoke and working years. The concentrations of 2-OHNAP is84.97(46.49, 174.45) pg/μg creatinine, and the major influencing factors are gender,age and smoke.2. Discussion on coke oven workers’ telomere length of DNA in peripheral blood, oxcidant damage effectThe telomere length of exposure group and control group respectively are0.75(0.51, 1.08) and 1.05(0.76, 1.44), and the differences between the two groups arestatistically significant(Z=7.692, P<0.001). The T-AOC of the two groups are 11.96(8.88, 14.68) and 14.55(10.51, 19.24) respectively, and the differences between the two groups are statistically significant(Z=6.614, P<0.001). There is no obvious correlation between the indexes about oxcidant damage and telomere length.BMD research showed: the BMDL of COEs is 1.839 mg/m3 per year. The BMDL of 1-OHPYR is 43.254 pg/μg creatinine, and 3-OHPHE is 11.369 pg/μg creatinine.3. The relationship of coke oven workers’ telomere length and gene polymorphisms and expressions of m RNAIn exposure group, the telomere length of CC genotype on rs3813867 site of CYP2E1 is 0.97(0.70, 1.20), and the length is greater than GG genotype’s 0.73(0.50,1.09). The differences are statistically significant(Z=2.536, P=0.011).The m RNA expressions of P21, TPP1, TRF1 and TRF2 in exposure group are all inferior to the control group(P<0.05). The m RNA expressions of P53 and POT1 are higher than control group(P<0.05). The m RNA expressions of P53, POT1, TIN2 and TRF2 are all negatively correlated with telomere damage(P<0.05). The m RNA expressions of TRF1 are positively correlated with telomere damage(P=0.015).The POT1 m RNA expressions of AA genotype on rs10250202 site of POT1 gene in exposure group are lower than that in control group(P=0.041). The P21 m RNA expressions of all genotypes on rs1801270 and rs1059234 of P21 gene in exposure group are lower than that in control group(P<0.05). The P53 m RNA expressions of all genotypes on rs1042522,rs1625895 site and SS genotype on rs17878362 site of P53 gene in exposure group are all higher than those in control group(P<0.05). The TRF1 m RNA expressions of all genotypes on rs3863242 site of TRF1 gene in exposure group are all lower than that in control group(P<0.001).4. Multivariate analysis of the influences on coke oven workers’ telomere lengthThe exposure group(independent variable) has the negative correlation with telomere length(dependent variable) in the 15th-75 th quantile. The gender variable has the positive correlation with telomere length in the 75 th quantile. The age variable has the negative correlation with telomere length in the 50 thquantile.The concentration ofexposure variable has the negative correlation with telomere length in the5th- 25 th quantile. Gene polymorphism of rs2736098 site on TERT gene has the positive correlation with telomere length in the 75 th quantile. Gene polymorphism of rs17878362 site on P53 gene has the positive correlation with telomere length in the75th- 95 th quantile. Gene polymorphism of rs3813867 site on CYP2E1 gene has the positive correlation with telomere length in the 25 th quantile.The m RNA expression of TPP1 gene has the positive correlation with telomere length in the 75th-85 th quantile. The m RNA expression of TRF1 gene has the negative correlation with telomere length in the 75 th quantile. The m RNA expression of P53 gene has the negative correlation with telomere length in the 75 thquantile. The m RNA expression of RAP gene has the negative correlation with telomere length in the 15 th quantile. The m RNA expression of TIN2 gene has the negative correlation with telomere length in the 85 thquantile.Conclusions1.Telomere length of DNA in peripheral white blood cells and 1-OHPYR in urine could be the biomarker of effect and exposure biomarker. The BMDL of COEs and 1-OHPYR through BMD method could provide the evidence to occupational exposure limit and biological exposure limit.2. Single factor analysis: Gene polymorphism of rs3813867 site on CYP2E1 gene can affect telomere length, and it could be a biomarker of susceptibility on telomere length. The shortening of telomere could have a connection with the increasing m RNA expression of P53, POT1, TIN2, TRF2 and the decreasing m RNA expression of TRF1.3. Quantile regression method was used to explore the influences on telomere length: exposure concentration, the m RNA expressions of P53, RAP, TIN2 and TRF1 may be the risk factors to telomere length. The m RNA expression of TPP1, AA genotype of rs2736098 on TERT gene, SL genotype of rs17878362 on P53 gene and CC genotype of rs3813867 on CYP2E1 gene maybe the risk factors to telomere length.Key words:... |
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