title: miR146a impairs the IFN-induced anti-HBV immune response by downregulating STAT1 in hepatocytes.
abstract: OBJECTIVE
  Previous studies have shown that hepatitis B virus (HBV) interferes with host antiviral immunity via multiple pathways. In clinical practice, interferon resistance is a serious issue for treatment of HBV infection. Now, miRNAs have been reported to be widely involved in antiviral immunity and have become a novel tool to study virus-host interaction. We question whether miRNAs play a role in HBV-induced interferon resistance in hepatocytes.
  
  
  METHODS
  MiRNAs levels in HepG2 and HepG2.2.15 cells were compared by qRT-PCR. The effects of miR146a on HBV infection were characterized by interference miR146a level, followed by the quantification of HBV mRNA, DNA and antigens. We employed qRT-PCR and western blot to study the effects of miR146a on the IFN-α signalling pathway. The miR146a promoter activity was validated by a luciferase reporter assay.
  
  
  RESULTS
  HBV infection impaired IFN-α signalling pathway in hepatocytes. MiR146a was upregulated in HBV+ HepG2.2.15 cells, and the transcriptional activity of miR146a in HepG2.2.15 cells was increased compared with HepG2 cells. HBV infection, especially the introduction of HBx, induced miR146a expression in vitro. Moreover, miR146a attenuated the production of type I interferon-induced antiviral factors. Low STAT1 levels were noticed in HBV+ HCC cells, and the luciferase reporter assay showed that STAT1 was post-transcriptionally downregulated by miR146a. Furthermore, the silencing of miR146a by antisense inhibitors enhanced IFN-α-mediated anti-HBV efficiency.
  
  
  CONCLUSIONS
  Our findings demonstrate that HBV infection promotes miR146a transcription, which represses STAT1 and results in interferon resistance. These observations reveal a novel role for miR146a in HBV immunopathogenesis, and provide a potential target for the therapeutic recovery of IFN-α-induced anti-HBV effects.
authors.affiliation: Institute of Immunopharmacology & Immunotherapy, School of Pharmaceutical Sciences, Shandong University, Jinan, China.
authors.forename: Zhao H
authors.initials: ZH
authors.lastname: Hou
authors.forename: Qiu J
authors.initials: QJ
authors.lastname: Han
authors.forename: Cai
authors.initials: C
authors.lastname: Zhang
authors.forename: Zhi G
authors.initials: ZG
authors.lastname: Tian
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
mesh_terms: D001665:Binding Sites; D015536:Down-Regulation; D024882:Drug Resistance, Viral / Q000235:genetics; D056945:Hep G2 Cells; D006515:Hepatitis B virus / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D022781:Hepatocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism / Q000821:virology; D054884:Host-Pathogen Interactions; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000494:pharmacology*; D035683:MicroRNAs / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D011994:Recombinant Proteins / Q000494:pharmacology; D050794:STAT1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D000077190:Interferon alpha-2; D016898:Interferon-alpha; C542542:MIRN146 microRNA, human; D035683:MicroRNAs; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human
keywords: HBV; STAT1; innate immunity; miR146a; type I interferon