Objective: To study PD-1 and PD-L1 expressions during 24 weeks telbivudine antiviral treatment in patients with chronic hepatitis B (CHB) and to explore the relationship between PD-1 expression and HBeAg/HBeAb seroconversion.
Methods: Ten CHB cases with HLA-A2 and HBeAg positive were treated with telbivudine 600 mg/d orally for 24 weeks. Fresh blood samples were collected at week 0, 12 and 24 after treatment. HBV-specific CD8+ T cells were expanded in vitro. Cell culture medium were collected for interferon gamma (IFNgamma) detection. Flow cytometry was used to detect the HLA-A type, PD-1, PD-L1 and HBV specific CD8+ T cells. The expressions of PD-1 and PD-L1, the counts of HBV-specific CD8+ T cells in circulating CD8+ lymphocytes, and IFNgamma concentration in culture medium were evaluated during antiviral treatment.
Results: At week 0, 12 and 24 after telbivudine treatment, 7 of 10 patients were HBV DNA undetectable, 2 were HBeAg seroconversion and 2 were HBeAg lose but anti-HBe negative. The frequency of PD-1-positive PBMCs were 52.1%+/-17.0%, 39.1%+/-18.2% and 23.4%+/-16.3% (week 24 vs week 0, P < 0.01) respectively; PD-L1 positive PBMCs were 45.6%+/-15.4%, 34.6%+/-16.2% and 20.9%+/-9.5% respectively(week 24 vs week 0, P < 0.01; week 24 vs week 12, P < 0.05). The frequency of PD-1-positive CD8+ T cells were 76.2%+/-10.4%, 66.5%+/-15.4% and 49.5%+/-25.3% respectively (week 24 vs week 0, P < 0.01; week 12 vs week 0, P < 0.05; week 24 vs week 12, P < 0.05); HBV-specific CD8 cells were 1.3%+/-0.5%, 1.5%+/-1.0% and 2.2%+/-1.5%; IFNgamma levels in cell culture medium were (91.7+/-82.1) pg/ml, (99.4+/-93.5) pg/ml and (109.5+/-86.6) pg/ml. A remarkable decrease of PD-1 and PD-L1 expressions and increase of HBV-specific CD8+ T cells were observed in patients who had HBeAg/HBeAb seroconversion at week 24.
Conclusions: Direct suppression of HBV replication by telbivudine in CHB patients can decrease PD-1 and PD-L1 expressions and restore HBV-specific CD8+T cells. The relationship between the changes of PD-1 expression and HBeAg/HBeAb seroconversion during antiviral therapy in HBeAg-positive patients need to confirm by future study.