Aberrant expression and dysfunction of TLR2 and its soluble form in chronic HBV infection and its regulation by antiviral therapy

Abstract Toll-like receptor 2 (TLR2) plays an important role in the immunopathogenesis of hepatitis B virus (HBV) infection. The relationship between TLR2 expression and clinical outcome of chronic HBV infection is not yet elucidated in details so far. Here, we employed clinical cohorts to investigate TLR2 expression and function in different phases of HBV infection and dynamic changes of TLR2 expression in HBeAg-positive chronic hepatitis B (CHB) patients during antiviral therapy. TLR2 was mainly expressed in monocytes and its ligand stimulation resulted in TNF-α, IL-6 and IL-10 production. Serum soluble TLR2 (sTLR2) levels were negatively correlated with TLR2 mRNA in PBMCs. As compared with immunotolerant carriers and inactive carriers, CHB patients showed an elevated TLR2 expression and TNF-α, IL-6 induction in PBMC, but had a decreased level of sTLR2 in serum. However, TLR2 expression and TNF-α induction in monocytes of CHB patients remained lower than healthy controls. Furthermore, higher TLR2 expression in PBMCs and lower level of sTLR2 in serum at baseline were predictive of a complete response to 52 weeks of telbivudine (LdT) therapy. Temporal dynamic analysis showed that TLR2 expression was restored with viral suppression and ALT normalization from week 12 to 24. However, peg-IFN-α-2a therapy induced a slightly decline in TLR2 expression. In conclusion, TLR2 expression and function in monocytes were impaired by chronic HBV infection. Higher TLR2 expression in PBMC and lower level of sTLR2 in serum at baseline were associated with a complete response to LdT therapy, and dynamic TLR2 expression was differently regulated by LdT and peg-IFN-α-2a therapy.