Methylation of forkhead box protein 3 gene promoter in CD4+ T cells in patients with chronic hepatitis B

Abstract

Objective To investigate the methylation status and expression of FOXP3 in CD4+ T cells of patients with chronic hepatitis B (CHB). Methods Peripheral blood mononuclear cells (PBMCs) from 59 CHB patients and 22 healthy controls (HC) were collected. The percentage of CD4+ CD25+ Foxp3+ Tregs in CD4+ T cells was estimated by flow cytometry. FOXP3 expression was measured by quantitative real time-polymerase chain reaction (RT-qPCR) and Western blotting. The methylation status of FOXP3 was determined by methylation-specific polymerase chain reaction. Results The percentage of CD4+ CD25+ pFoxp3+ Tregs in CD4+ T cells, FOXP3 mRNA and protein expression levels were significantly higher in patients with CHB than HCs (P<0.05). Meanwhile, the methylation frequency of FOXP3 was significantly lower in CHB patients than HCs (P<0.05). FOXP3 mRNA levels and the percentage of CD4+ CD25+ Foxp3+ Tregs were significantly lower (P<0.05) in patients with gene methylation than those without. Conclusions Aberrant demethylation of FOXP3 gene existed in CD4+ T cells of CHB, which contributed to an elevation in FOXP3 expression and percentage of CD4+ CD25+ Foxp3+ Tregs. It might provide a new target for prevention and treatment of CHB. Key words: Forkhead box protein 3; methylation; chronic hepatitis B; CD4+ 25+ Foxp3+ regulatory T cells