Multifaceted Defects in Monocytes in Different Phases of Chronic HBV Infection: Persistence After Antiviral Therapy

Background: Monocytes play an important role in the control of microbial infection but monocyte biology during chronic HBV infection (CHI) remains inadequately studied. We investigated the frequency/phenotype/functions of monocytes in different phases of CHI namely, Immune-tolerant (IT), HBeAg-positive/HBeAg-negative (EP/EN) chronic hepatitis B (CHB) and Inactive carriers (IC), identified factors responsible for their functional alterations and determined the impact of antiviral-therapy on these cells. Methods Multicolor flow cytometry/cell-sorting/co-culture experiments/confocal microscopy were performed. Results HLA-DR + CD14 ++ CD16 − classical-monocytes were found to be significantly reduced while HLA-DR + CD14 ++ CD16 + intermediate- and HLA-DR + CD14 + CD16 ++ non-classical-monocyte-subsets were expanded in IT and EP-/EN-CHB than IC and healthy controls (HC). In comparison to IC/HC, monocytes (including all subsets) in IT/CHB exhibited diminished expression of TLR-2/TLR-4/TLR-9 and cytokines IL-12/TNF-α/IL-6 but produced higher levels of IL-10/TGF-β. Further, monocytes in CHB/IT showed impaired phagocytosis and oxidative response relative to IC/HC. In vitro assays indicated that high titres of hepatitis B surface antigen (HBsAg) present in IT/CHB and IL-4 in CHB triggered the functional defects in monocytes via induction of β-catenin. Additionally, monocyte-derived M1-macrophages of CHB/IT produced less pro-inflammatory and more anti-inflammatory cytokines than those of IC/HC whereas, monocytes in CHB/IT skewed the differentiation of CD4 + -T-cells towards regulatory T-cell and Th2-dominated phenotype. Moreover, in CHB/IT, monocytes overexpressed chemokine-receptor CCR2, which coincided with increased intrahepatic accumulation of β-catenin + CD14 + -cells. One-year of Tenofovir-therapy failed to normalize monocyte functions or reduce serum HBsAg/IL-4 levels. Conclusions Monocytes are functionally perturbed mostly in IT and EP-/EN-CHB phases. Targeting intramonocytic β - catenin or reducing HBsAg/IL-4 levels might restore monocyte function and facilitate viral clearance.