Distinct antiviral signaling pathways in primary human hepatocytes and their differential disruption by HCV NS3 protease.
Laboratoire d'immunologie virale, Centre de Recherche du CHUM (CRCHUM), Hôpital Saint-Luc, 264 René Levesque-Est, PEA 312, Québec, Canada.
BACKGROUND & AIMS: Molecular sensors recognize viral nucleic acids and initiate events that subsequently enable cells to control and clear infection. Hepatitis C Virus (HCV) can interfere with the innate host response and the NS3/4A protease was reported to specifically block antiviral signaling pathways, a finding that had yet to be studied in human primary hepatocytes. METHODS: Freshly isolated human primary hepatocytes, transduced with a lentiviral vector expressing HCV NS3/4A were stimulated with extracellular and intracellular double-stranded RNA (dsRNA) and the innate immune antiviral genes were quantified by quantitative PCR and microarrays analysis. RESULTS: We demonstrate that sensing receptors of human hepatocytes in primary cultures are stimulated following recognition of either mode of dsRNA delivery, inducing transcriptional up-regulation (over 100-fold) of multiple immune genes, either selectively or independently of recognition pathways. We also report that the intracellular dsRNA-activated innate response is severely compromised upon ectopic expression of the HCV NS3/4A protease gene in normal human primary hepatocytes, and completely restored by treatment with the NS3/4A protease specific inhibitor BILN2061. CONCLUSIONS: The present study indicates that NS3/4A has a wider protease-dependent effect on the intracellular Pathogen Recognition Receptor (PRR)-mediated immune response than on its extracellular counterpart, which underlies the major role of cytosolic dsRNA receptors in HCV recognition by primary human hepatocytes.
J. Hepatol. 2010;52(2):167-75.
Pubmed ID: 20006398