Distinct antiviral signaling pathways in primary human hepatocytes and their differential disruption by HCV NS3...

Area of Science:

• Hepatology
• Virology
• Immunology

Background:

• Hepatitis C Virus (HCV) can evade host innate immunity.
• The HCV NS3/4A protease is implicated in blocking antiviral signaling pathways.
• Previous studies had not investigated this mechanism in primary human hepatocytes.

Purpose of the Study:

• To investigate the role of HCV NS3/4A protease in modulating the innate immune response in human primary hepatocytes.
• To determine the effect of HCV NS3/4A on cellular sensing of viral nucleic acids.
• To assess the efficacy of a specific NS3/4A protease inhibitor in restoring antiviral responses.

Main Methods:

• Human primary hepatocytes were transduced with a lentiviral vector expressing HCV NS3/4A.
• Cells were stimulated with extracellular and intracellular double-stranded RNA (dsRNA).
• Innate immune gene expression was quantified using quantitative PCR and microarrays.

Main Results:

• Hepatocyte sensing receptors were activated by both extracellular and intracellular dsRNA, inducing significant immune gene upregulation.
• Ectopic expression of HCV NS3/4A severely compromised the intracellular dsRNA-activated innate immune response.
• Treatment with the NS3/4A protease inhibitor BILN2061 completely restored the compromised innate immune response.

Conclusions:

• HCV NS3/4A protease has a significant protease-dependent inhibitory effect on intracellular Pathogen Recognition Receptor (PRR)-mediated immunity.
• Cytosolic dsRNA receptors play a crucial role in HCV recognition by primary human hepatocytes.
• Targeting NS3/4A protease is a potential therapeutic strategy to restore antiviral immunity against HCV.