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.