Background
The negative signal provided by some co‐inhibitory factors such as programmed cell death‐1 (PD‐1) has been associated with chronic hepatitis B (CHB) infection induced‐T cell exhaustion, although the correlation of CpG methylation of the Pdcd1 gene with PD‐1 expression and medical laboratory indicators in CHB infection has not yet been elucidated.
Methods
Blood samples from 20 CHB infection patients and 20 spontaneous clearance (SC) patients were collected. Percentages of PD‐1‐positive CD8+ T cells were analyzed by flow cytometry. The percentage of CpG methylation at the Pdcd1 locus was analyzed by bisulfite sequencing. Student's t test, Pearson and Spearman's correlation, and Mann–Whitney tests were used in the statistical analysis.
Results
Percentages of PD‐1‐positive CD8+ T cells in peripheral blood T cells were significantly higher in CHB patients than in the SC group (p < 0.001). The methylation level of Pdcd1 was significantly lower in CHB patients (p < 0.001) and the methylation level of Pdcd1 was negatively correlated with PD‐1 expression level in CD8+ T cells (p < 0.001) and hepatitis‐B surface antigen (HBsAg) (p < 0.001).
Conclusions
The results of the present study suggest that Pdcd1 methylation is correlated with PD‐1 expression on CD8+ T cells and correlated with HBsAg and alanine aminotransferase. The results may provide new ideas regarding anti‐PD‐1 inhibitors, and epigenetic regulators such as demethylation inhibitors could represent more successful therapeutic strategies in hepatitis B infection patients.