| Background and ObjectiveHepatitis B virus (HBV) infection is a global public health problem across the world. DNA methyltransferase (DNMT) is a major regulating factor of DNA methylation. Our study was to determine the relationship between DNMT expression and HBV-infection; and clarify whether its expression pattern is associated with the degree of hepatitis; in addition, to research whether its expression is associated with methylation of certain genes, such as glutathione peptide sulfhydryl transferase P1 (GSTP1) and glutathione S-transferase M3 (GSTM3) and so on.Patients and MethodsIn our study,153 patients with CHB and 40 healthy controls were enrolled in Qilu Hospital of Shandong University from June 2012 to July 2014. DNA and mRNA of patients with CHB and normal controls were respectively extracted from peripheral blood mononuclear cells (PBMCs). DNMT1, DNMT3a and DNMT3b mRNA were detected by real-time reverse-transcription polymerase chain reaction (RT-PCR). Levels of plasma soluble TNFaand oxidative stress parameter, malondialdehyde (MDA) was detected by enzyme linked immunosorbent assay (ELISA). The methylation status of GSTP1 and GSTM3 were detected by methylation-specific PCR (MSP) analysis.ResultsIn patients with chronic hepatitis B, GSTM3 and DNMT1 mRNA levels [1.3×10-3 (0.6×10-3,6.8×10-3); 1.9×10-3 (0.8×10-3,5.8×10-3)] were significantly higher than the control group [0.5×10-3 (0.1×10-3,4.2 ×10-3); 0.5×10-3 (0.2×10-3,4.2×10-3)], the difference is statistically significant (P=0.001). GSTP1, GSTM3 promoter methylation have a significant positive correlation with DNMT1, DNMT3a, TNF, MDA and HBeAg. DNMT1 and DNMT3a have a significant positive correlation with MDA (rs=0.405, P<0.001; rs=0.391, P<0.001) and TNF (rs= 0.281, P<0.001; rs=0.370, P<0.001), however, there was no associations of DNMT3b with MDA (rs=0.110, P=0.177) and TNF(rs=0.015,0.857). Moreover, none of the three DNMTs (DNMT1 rs=0.077, P=0.343; DNMT3a,rs=0.099, P=0.225; DNMT3b, rs=0.113, P =0.163) had correlations with HBV DNA load. In HBeAg-positive group the GSTP1 promoter methylation was higher than HBeAg-negative group. The DNMT1 and DNMT3a mRNA level in patients with HBeAg positive [1.7×10-3 (0.9×10-3,29×10-3); 4×10-3 (1.2×10-3,17.5×10-3)] was higher than that in patients with HBeAg negative [0.9×10-3 (0.5× 10-3,2.3×10-3); 1.4×10-3 (0.6×10-3,4.3×10-3)]. The DNMT1 and DNMT3a mRNA level in patients with GSTP1 promoter methylation [9.2 ×10-3 (1.3×10-3,13.0×10-3); 10.9×10-3 (3.5×10-3,49.4×10-3)] was higher than that in patients with unmethylation groups[1.2×10-3 (0.6× 10-3,5.1×10-3); 1.8×10-3 (0.7×10-3,5.1×10-3)].ConclusionsIn CHB patients, the presence of positively correlation between DNMT and indicators of oxidative damage, suggesting that DNMT’ expression may be involved in the pathogenesis of CHB; in addition, DNMT is one of the causes of certain gene’ methylation in CHB patients, suggesting that DNMT can serve as a diagnostic candidate and therapeutic targets,which we can deeply explored in future studies. HBeAg-positive CHB patients have higher DNMT expression than negative patients, suggesting that DNMT level could be used as an early marker of HBeAg seroconversion. |
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