Study Of The Relationships Between The Methylation Of CYP1A1/GSTP1 Gene Promoter CpG Island And Antituberculosis Drug-induced Hepatic Injury

Objectives CYP1A1 and GSTP1 are important members of cytochrome P450(CYP)and glutathione S-transferase(GST) families, in the present study, we investigated the effects of CYP1A1 and GSTP1 changes in promoter Cp G island methylation on the development of anti-tuberculosis(anti-TB) drug-induced hepatic injury(ADIH) in patients with TB.Methods 1 Subjects: We used a one-to-one matched case-control design, the study participants included 127 patients with TB and ADIH(case group) and 127 patients with TB but without liver injury(control group) during six months follow up while on antituberculosis treatment. 2 Epidemiological investigation: The general condition of patients and other basic information were obtained through an epidemiological survey during this period of time, including sex, age, height, weight, marital status, education,profession, smoking, drinking, past medical history, therapeutic regimen, and liver function examination results. After an informed consent was obtained, venous blood was collected from each subject and then stored at-80℃. 3 Laboratory tests: The salting-out method was used to extract genomic DNA and polymerase chain reaction-restriction fragment length polymorphism analysis(PCR-RFLP) was performed to detect the genotypes of CYP1A1(MspⅠ) and GSTP1(Ile105Val) genes; The genomic DNA isolated from plasma was modified with sodium bisulfite using an EZ DNA methylationgold kit and the methylation-specific PCR(MSP) method was used to detect the methylation levels of GSTP1 and CYP1A1 in plasma-free DNA. 4 Statistical analysis:Univariate analysis and multivariate analysis of risk factors were all done by conditional logistic regression to compare ADIH patients with their matched controls for the general factors, including marital status, education, profession, body mass index(BMI), smoking,drinking, and CYP1A1 and GSTP1 genotypes, methylation status. Statistical analyses were performed using SPSS for windows, version 17.0. P<0.05 was considered statistically significant.Results 1 Univariate analysis:We analyzed the distribution of risk factors in the two groups by the conditional logistic regression method, including marital status, education,profession, body mass index, smoking, drinking, and polymorphisms of CYP1A1 andGSTP1, we found that drinking was significantly different between the two groups; 2Relationships of CYP1A1 and GSTP1 methylation on ADIH risk: We found that ADIH patients had significantly higher CYP1A1 and GSTP1 promoter methylation rates than those of control subjects(OR=2.000 and 2.467, respectively). To eliminate the effects of gene polymorphisms, we analyzed the relationships between methylation status and polymorphisms of CYP1A1/GSTP1 genes, the results showed that there were no relationships between CYP1A1 and GSTP1 polymorphisms and methylation. Eventually,after having adjusted for drinking, polymorphisms of CYP1A1 and GSTP1, which was significantly different between the groups based on previous studies, we found that CYP1A1 and GSTP1 promoter hypermethylation were associated with ADIH(OR=1.962 and 2.660, respectively). 3 Interactions analysis of CYP1A1 and GSTP1 gene methylation status: the results showed that there was an synergistic effect between the two genes methylation status, the risk to ADIH with combination of CYP1A1 gene methylation and GSTP1 gene methylation was higher than both unmethylation patients(OR=17.885).Conclusions 1 Hypermethylation of Cp G islands of CYP1A1 and GSTP1 promoters may play important roles in the development of ADIH, and provide evidence of being used as novel markers for ADIH risk prediction. 2 There is an synergistic effect between two genes methylation, the patients with combination of CYP1A1 and GSTP1 gene methylation have a higher risk of ADIH.