OBJECTIVETo investigate the dynamic changes in expression of programmed death (PD)-1, Toll-like receptor (TLR)3, and TLR4 on the surface of peripheral blood mononuclear cells (PBMCs) in patients with chronic hepatitis C (CHC) that occur in response to pegylated-interferon alpha-2a (peg-IFNalpha-2a) plus ribavirin (RBV) combination therapy, and to analyze the relation to achievement of sustained virological response (SVR). METHODS Twenty-three CHC patients and 10 healthy controls were enrolled in the study. All CHC patients underwent 48 weeks of combination therapy with peg-IFNalpha-2a (180 microg, subcutaneous injection, once weekly) plus RBV (15 microg/kg, oral, once daily). Total PBMCs were isolated from both groups (CHC patients at treatment week 0, 12, 24, and 48 and post-treatment week 24; controls at enrollment) and subjected to flow cytometric analysis of PD-1, TLR3, and TLR4 surface expression. In addition, serum levels of alanine aminotransferase (ALT) and hepatitis C virus (HCV) RNA levels were analyzed by enzymatic assay and the AmpliPrep/COBAS (Roche) nucleic acid amplification test, respectively. SVR was defined as undetectable levels of HCV RNA at post-treatment week 24. Intergroup differences were assessed by one-way ANOVA.

RESULTSThe expression ratios of PD-1, TLR4 and PD-1: TLR4 on PBMCs were significantly higher in CHC patients before therapy than in the healthy controls (45.20 +/- 7.12% vs. 16.82 +/- 4.13%, 58.45 +/- 15.13% vs. 21.09 +/- 2.89%, and 35.54 +/- 7.69% vs. 14.12 +/- 2.89%; all P < 0.05). In contrast, the expression ratios of TLR3 and PD-1:TLR3 were slightly, but not significantly, higher in CHC patients before therapy than in the healthy controls (P > 0.05). During the course of peg-IFNalpha-2a plus RBV combination therapy, the expression ratios of PD-1 and TLR4 on PBMCs showed a decreasing trend, while TLR3 expression showed an increasing trend. Furthermore, CHB patients who achieved SVR at post-treatment week 24 had a significantly different expression ratio of PD-1 and TLR3 than those who did not achieve SVR (P < 0.05).

CONCLUSIONSurface expression of PD-1, TLR4, and PD-1:TLR4 is up-regulated in the total PBMCs of CHC patients. Peg-IFNalpha-2a plus RBV treatment-induced suppression of HCV replication results in a significant reduction in PD-1 and TLR4 expression on the surface of PBMCs, but a remarkably elevated level of TLR3 expression. The dynamic change in PD-1 and TLR3 expression on PBMCs that occurs during antiviral therapy may be related to achievement of SVR.