title: Independent, parallel pathways to CXCL10 induction in HCV-infected hepatocytes.
abstract: OBJECTIVE
  The pro-inflammatory chemokine CXCL10 is induced by HCV infection in vitro and in vivo, and is associated with outcome of IFN (interferon)-based therapy. We studied how hepatocyte sensing of early HCV infection via TLR3 (Toll-like receptor 3) and RIG-I (retinoic acid inducible gene I) led to expression of CXCL10.
  
  
  METHODS
  CXCL10, type I IFN, and type III IFN mRNAs and proteins were measured in PHH (primary human hepatocytes) and hepatocyte lines harboring functional or non-functional TLR3 and RIG-I pathways following HCV infection or exposure to receptor-specific stimuli.
  
  
  RESULTS
  HuH7 human hepatoma cells expressing both TLR3 and RIG-I produced maximal CXCL10 during early HCV infection. Neutralization of type I and type III IFNs had no impact on virus-induced CXCL10 expression in TLR3+/RIG-I+ HuH7 cells, but reduced CXCL10 expression in PHH. PHH cultures were positive for monocyte, macrophage, and dendritic cell mRNAs. Immunodepletion of non-parenchymal cells (NPCs) eliminated marker expression in PHH cultures, which then showed no IFN requirement for CXCL10 induction during HCV infection. Immunofluorescence studies also revealed a positive correlation between intracellular HCV Core and CXCL10 protein expression (r(2) = 0.88, p ≤ 0.001).
  
  
  CONCLUSIONS
  While CXCL10 induction in hepatocytes during the initial phase of HCV infection is independent of hepatocyte-derived type I and type III IFNs, NPC-derived IFNs contribute to CXCL10 induction during HCV infection in PHH cultures.
authors.affiliation: Department of Global Health, Pathobiology Program, University of Washington, Seattle, WA, United States.
authors.forename: Jessica
authors.initials: J
authors.lastname: Brownell
authors.forename: Jessica
authors.initials: J
authors.lastname: Wagoner
authors.forename: Erica S
authors.initials: ES
authors.lastname: Lovelace
authors.forename: Derek
authors.initials: D
authors.lastname: Thirstrup
authors.forename: Isaac
authors.initials: I
authors.lastname: Mohar
authors.forename: Wesley
authors.initials: W
authors.lastname: Smith
authors.forename: Silvia
authors.initials: S
authors.lastname: Giugliano
authors.forename: Kui
authors.initials: K
authors.lastname: Li
authors.forename: I Nicholas
authors.initials: IN
authors.lastname: Crispe
authors.forename: Hugo R
authors.initials: HR
authors.lastname: Rosen
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Polyak
mesh_terms: D002460:Cell Line; D054357:Chemokine CXCL10 / Q000096:biosynthesis* / Q000235:genetics; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000378:metabolism; D016174:Hepacivirus / Q000276:immunology* / Q000472:pathogenicity*; D019698:Hepatitis C, Chronic / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D022781:Hepatocytes / Q000276:immunology* / Q000378:metabolism / Q000821:virology*; D006801:Humans; D007372:Interferons / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D009500:Neutralization Tests; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011971:Receptors, Immunologic; D051196:Toll-Like Receptor 3 / Q000378:metabolism
chemical_list: C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; D012333:RNA, Messenger; D011971:Receptors, Immunologic; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; D007372:Interferons; C452820:RIGI protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases
keywords: AP-1; HCV; IFIT1; IFN; IFN-induced protein with tetratricopeptide repeats 1; IRF; ISG; ISRE; KCs; Kupffer cells; LSECs; MAVS; MOI; NF-κB; NK; NPCs; Non-parenchymal cells; PAMP; PHH; PRR; RIG-I; STAT; TIR-domain-containing adapter-inducing IFN-β; TLR3; TNF-α; TRIF; Toll-like receptor 3; Type I interferon; Type III interferon; activator protein-1; hepatitis C virus; interferon; interferon regulatory factor; interferon stimulated gene; interferon stimulated response element; liver sinusoidal endothelial cells; mitochondrial antiviral-signaling protein; multiplicity of infection; natural killer; non-parenchymal cells; nuclear factor-κB; pathogen associated molecular pattern; pattern recognition receptor; primary human hepatocytes; retinoic acid inducible gene I; signal transducer and activator of transcription; tumor necrosis factor α