Activation of chemokine and inflammatory cytokine response in hepatitis C virus–infected hepatocytes depends on toll-like receptor 3 sensing of hepatitis C virus double-stranded RNA intermediates

Abstract

Chemokines and inflammatory cytokines are key regulators of immunity and inflammation during viral infections. Hepatitis C virus (HCV) is a hepatotropic RNA virus frequently associated with chronic liver inflammation and hepatocellular carcinoma. Intrahepatic levels of chemokines and cytokines are elevated in chronic HCV infections, but the underlying mechanisms remain unclear. We find that Toll like receptor-3 (TLR3) senses HCV infection in cultured hepatoma cells, leading to NF-κB activation and the production of numerous chemokines and inflammatory cytokines, such as RANTES, MIP-1α, MIP-1β, IP-10 and IL-6. The chemokine/cytokine induction occurred late in HCV infection and was abrogated when HCV was UV-inactivated prior to infection, indicating a dependence on cellular recognition of HCV replication products. Gel shift and chromatin immunoprecipitation assays revealed that NF-κB plays a pivotal role in HCV-induced chemokine/cytokine transcription. Mutations specifically disrupting the dsRNA binding activity of TLR3 ablated the chemokine/cytokine response to HCV infection, indicating that HCV dsRNA was the pathogen associated molecular pattern triggering TLR3 signaling. In vitro synthesized HCV dsRNAs with a minimal length of ~80-100 bp activated TLR3-dependent chemokine expression, regardless of the genome position from which they derive. In contrast, HCV ssRNAs, including those derived from the structured 3′NTR highly potent for RIG-I activation, failed to do so. Moreover, robust production of chemokines and inflammatory cytokines was also observed in primary human hepatocytes following stimulation with extracellular poly-I:C, a TLR3 ligand. Conclusion Our data suggest that TLR3-mediated chemokine and inflammatory cytokine responses may play an important role in host immune responses to HCV and the pathogenesis of HCV-associated liver diseases.

Laboratory Markers of Liver Damage in Chronic Hepatitis C

“…The data, to a certain extent, are consistent with the results obtained by other authors, who confirmed the compliance of increased HA and TNF-α levels in blood with fibrosis extent in hepatic tissue [7][8][9][13][14][15]. According to Yushchuk et al [7], the diagnostic efficiency of HA to stratify FIII stage in chronic hepatitis from FIV in hepatic cirrhosis has 100% sensitivity and 84.6% specificity.…”

Direct, Interferon-Independent Activation of the CXCL10 Promoter by NF-κB and Interferon Regulatory Factor 3 during Hepatitis C Virus Infection

“…Recently, Li et al showed that HCV infection of TLR3-expressing hepatoma cells can induce NF-B binding to the CXCL10 promoter (4). While this study indicates that NF-B is a critical regulator of CXCL10 induction during early HCV infection, the other proinflammatory transcription factor binding sites annotated in the CXCL10 promoter (noted above) could provide additional levels of transcriptional regulation.…”

“…ecognition of viral components by pattern recognition receptors (PRRs) during hepatitis C virus (HCV) infection leads to the induction of various proinflammatory and antiviral genes, including interferons (IFNs), cytokines, and chemokines (1)(2)(3)(4)(5). The profile of induced genes depends upon the transcription factors that are active within the nucleus (1,(6)(7)(8).…”

Asunaprevir Evokes Hepatocytes Innate Immunity to Restrict the Replication of Hepatitis C and Dengue Virus

“…The two key cellular sensors are Toll-like receptor 3 (TLR3), which senses doublestranded RNA (dsRNA) within endosomes, and the RNA helicase retinoic acid-inducible gene I (RIG-I), which senses intracellular double-stranded RNA or single-stranded viral RNA (Wang et al, 2009;Green et al, 2012Green et al, , 2014Li et al, 2012;Horner and Gale, 2013). Signaling initiated by TLR3 and RIG-I is transmitted through the adaptor proteins Toll/IL-1 receptor domain-containing adaptor inducing IFN-beta (TRIF) and mitochondrial antiviral-signaling protein (MAVS) respectively, to interact with TNF receptor-associated factor 3 (TRAF3) and converge on the transcription factors, interferon regulatory factor 3 (IRF3) and NF-κB.…”