title: Reversal of hepatitis B virus-induced immune tolerance by an immunostimulatory 3p-HBx-siRNAs in a retinoic acid inducible gene I-dependent manner.
abstract: It is extensively accepted that hepatitis B virus (HBV) escapes from innate immunity by inhibiting type I interferon (IFN) production, but efficient intervention to reverse the immune tolerance is still not achieved. Here, we report that 5'-end triphosphate hepatitis B virus X gene (HBx)-RNAs (3p-HBx-short interfering [si]RNAs) exerted significantly stronger inhibitory effects on HBV replication than regular HBx-siRNAs in stably HBV-expressing hepatoplastoma HepG2.2.15 cells through extremely higher expression of type I IFNs, IFN-induced genes and proinflammatory cytokines, and retinoic acid inducible gene I (RIG-I) activation. Also, 3p-HBx-siRNA were more efficient to stimulate type I IFN response than HBx sequence-unrelated 3p-scramble-siRNA in HepG2.2.15 cells, indicating that a stronger immune-stimulating effect may partly result from the reversal of immune tolerance through decreasing HBV load. In RIG-I-overexpressed HepG2.2.15 cells, 3p-HBx-siRNAs exerted stronger inhibitory effects on HBV replication with greater production of type I IFNs; on the contrary, in RIG-I-silenced HepG2.2.15 cells or after blockade of IFN receptor by monoclonal antibody, inhibitory effect of 3p-HBx-siRNAs on HBV replication was largely attenuated, indicating that immunostimulatory function of 3p-HBx-siRNAs was RIG-I and type I IFN dependent. Moreover, in HBV-carrier mice, 3p-HBx-siRNA more strongly inhibited HBV replication and promoted IFN production than HBx-siRNA in primary HBV(+) hepatocytes and, therefore, significantly decreased serum hepatitis B surface antigen and increased serum IFN-β.
  
  
  CONCLUSIONS
  3p-HBx-siRNAs may not only directly inhibit HBV replication, but also stimulate innate immunity against HBV, which are both beneficial for the inversion of HBV-induced immune tolerance.
authors: Institute of Immunopharmacology & Immunotherapy, School of Pharmaceutical Sciences, Shandong University, Jinan, China.
authors: Qiuju
authors: Q
authors: Han
authors: Cai
authors: C
authors: Zhang
authors: Jian
authors: J
authors: Zhang
authors: Zhigang
authors: Z
authors: Tian
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004261:DNA Replication / Q000235:genetics / Q000276:immunology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D056945:Hep G2 Cells / Q000276:immunology / Q000502:physiology; D006515:Hepatitis B virus / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance / Q000235:genetics / Q000276:immunology; D007113:Immunity, Innate; D007114:Immunization; D051379:Mice; D008810:Mice, Inbred C57BL; D034741:RNA, Small Interfering / Q000235:genetics* / Q000276:immunology; D011863:Radioimmunoassay; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism*; D012680:Sensitivity and Specificity; D014162:Transfection
chemical_list: D034741:RNA, Small Interfering; D018168:Receptors, Retinoic Acid; C082927:retinoic acid binding protein I, cellular