Direct antiviral properties of TLR ligands against HBV replication in immune-competent hepatocytes

Abstract

Current therapies for chronic hepatitis B virus (HBV) infections are effective at decreasing the viral load in serum, but do not lead to viral eradication. Recent studies highlighted the therapeutic or “adjuvant” potential of immune-modulators. Our aim was to explore the direct anti-HBV effect of Toll-Like-Receptors (TLR) agonists in hepatocytes. HBV-infected primary human hepatocytes (PHH) or differentiated HepaRG cells (dHepaRG) were treated with various TLR agonists. Amongst all TLR ligands tested, Pam3CSK4 (TLR1/2-ligand) and poly(I:C)-(HMW) (TLR3/MDA5-ligand) were the best at reducing all HBV parameters. No or little viral rebound was observed after treatment arrest, implying a long-lasting effect on cccDNA. We also tested Riboxxol that features improved TLR3 specificity compared to poly(I:C)-(HMW). This agonist demonstrated a potent antiviral effect in HBV-infected PHH. Whereas, poly(I:C)-(HMW) and Pam3CSK4 mainly induced the expression of classical genes from the interferon or NF-κB pathway respectively, Riboxxol had a mixed phenotype. Moreover, TLR2 and TLR3 ligands can activate hepatocytes and immune cells, as demonstrated by antiviral cytokines produced by stimulated hepatocytes and peripheral blood mononuclear cells. In conclusion, our data highlight the potential of innate immunity activation in the direct control of HBV replication in hepatocytes, and support the development of TLR-based antiviral strategies.

Novel Potent Capsid Assembly Modulators Regulate Multiple Steps of the Hepatitis B Virus Life Cycle

“…Primary human hepatocytes (PHHs) were isolated from surgical liver resections, after informed consent of patients (kindly provided by M. Rivoire [CLB, Lyon]; agreements DC-2008-99 and DC-2008-101) as previously described (62) and cultured in complete William's medium supplemented with 1.8% of DMSO. Differentiated HepaRG (dHepaRG) cells and PHHs were infected as previously described (63), with HBV genotype D inoculum prepared either from HepG2.2.15 or HepAD38 cells. The multiplicities of infection (expressed as virus genome equivalent/ cell) are indicated in the figure legends.…”

Liver macrophages: Friend or foe during hepatitis B infection?

“…Some preliminary data have shown promising results for the use of TLR7 or TLR8, which are not expressed by hepatocytes, but are both present at the surface of liver macrophages. TLR2 agonist have been recently shown to induce a strong anti‐viral effect directly in hepatocytes, but also through the induction of liver immune cells and anti‐viral cytokines secretion . Additionally, specific inflammasome stimulations may induce a boost of IL‐1β secretion and ultimately an antiviral phenotype .…”

Polymorphisms in the Toll-like receptor 3 (TLR3) gene are associated with the natural course of hepatitis B virus infection in Caucasian population

“…Furthermore, TLR agonists also activate cytotoxic T lymphocyte responses and inhibit HBV propagation 7 – 9 , 37 . Triggering of TLR-mediated pathways will become critical in approaching host factor-targeted treatment strategies to cure HBV infection 35 , 38 . Thus, polymorphism in genes of key components of the TLR-signalling pathways might also affect individual therapy outcome.…”