BACKGROUND: The non-structural (NS) 3/4A protease/helicase of the hepatitis C virus is known to modulate signalling pathways in the infected hepatocyte by cleaving CARD adaptor inducing IFNβ (Cardif), T-cell protein tyrosine phosphatase (TC-PTP) and TIR domain-containing adaptor inducing IFNβ (TRIF), but the effects of NS3/4A in vivo still remain unclear. AIM: To investigate the influence of NS3/4A on intracellular and intercellular signalling in vivo by analysing the intrahepatic inflammatory response of naïve, lipopolysaccharide (LPS)/D-galactosamine (D-galN) or tumour necrosis factor-α (TNFα)/D-galN-treated NS3/4A-transgenic (Tg) mice. METHODS: The intrahepatic immunity of naïve and LPS/D-galN- or TNFα/D-galN-treated NS3/4A-Tg mice was determined using western blot, ELISA, real-time PCR, flow cytometry and survival monitoring. The injection of cytokines or antibodies against signalling components was performed to analyse the relevance of the respective pathways for the investigated issues. A Tg mouse lineage expressing an inactivated NS3/4A protease (NS3/4A(Ile1073Ala)-Tgs) was generated to examine if protective effects were NS3/4A protease dependent. RESULTS: The activation of hepatic signal transducer and activator of transcription 1 and 2 was impaired in NS3/4A-Tg mice after treatment with LPS/D-galN or TNFα/D-galN. This was paralleled by a reduction in hepatic interferon-γ (IFNγ). Reconstitution of IFNγ reverted the resistance to LPS/TNFα in NS3/4A-Tg mice. Subsequently, blocking IFNγ in vivo rendered wild-type mice resistant against treatment with LPS/TNFα. A new Tg mouse expressing an inactivated NS3/4A protease had the same phenotype as wild-type mice with respect to hepatic IFNγ levels and sensitivity to LPS/d-galN. Finally, the chemokine profile was altered in the NS3/4A-Tg mice towards an anti-inflammatory state, which helps to explain the altered immune cell subsets and reduction in hepatic IFNγ production. CONCLUSIONS: Our data demonstrate that the NS3/4A protease reduces the intrahepatic production of IFNγ and alters TNFα-mediated effects, thereby impairing the hepatic inflammatory response. This may contribute to viral persistence.
BACKGROUND: The non-structural (NS) 3/4A protease/helicase of the hepatitis C virus is known to modulate signalling pathways in the infected hepatocyte by cleaving CARD adaptor inducing IFNβ (Cardif), T-cell protein tyrosine phosphatase (TC-PTP) and TIR domain-containing adaptor inducing IFNβ (TRIF), but the effects of NS3/4A in vivo still remain unclear. AIM: To investigate the influence of NS3/4A on intracellular and intercellular signalling in vivo by analysing the intrahepatic inflammatory response of naïve, lipopolysaccharide (LPS)/D-galactosamine (D-galN) or tumour necrosis factor-α (TNFα)/D-galN-treated NS3/4A-transgenic (Tg) mice. METHODS: The intrahepatic immunity of naïve and LPS/D-galN- or TNFα/D-galN-treated NS3/4A-Tg mice was determined using western blot, ELISA, real-time PCR, flow cytometry and survival monitoring. The injection of cytokines or antibodies against signalling components was performed to analyse the relevance of the respective pathways for the investigated issues. A Tg mouse lineage expressing an inactivated NS3/4A protease (NS3/4A(Ile1073Ala)-Tgs) was generated to examine if protective effects were NS3/4A protease dependent. RESULTS: The activation of hepatic signal transducer and activator of transcription 1 and 2 was impaired in NS3/4A-Tg mice after treatment with LPS/D-galN or TNFα/D-galN. This was paralleled by a reduction in hepatic interferon-γ (IFNγ). Reconstitution of IFNγ reverted the resistance to LPS/TNFα in NS3/4A-Tg mice. Subsequently, blocking IFNγ in vivo rendered wild-type mice resistant against treatment with LPS/TNFα. A new Tg mouse expressing an inactivated NS3/4A protease had the same phenotype as wild-type mice with respect to hepatic IFNγ levels and sensitivity to LPS/d-galN. Finally, the chemokine profile was altered in the NS3/4A-Tg mice towards an anti-inflammatory state, which helps to explain the altered immune cell subsets and reduction in hepatic IFNγ production. CONCLUSIONS: Our data demonstrate that the NS3/4A protease reduces the intrahepatic production of IFNγ and alters TNFα-mediated effects, thereby impairing the hepatic inflammatory response. This may contribute to viral persistence.
Authors: Ravi Rajagopalan; Lin Pan; Caralee Schaefer; John Nicholas; Sharlene Lim; Shawn Misialek; Sarah Stevens; Lisa Hooi; Natalia Aleskovski; Donald Ruhrmund; Karl Kossen; Lea Huang; Sophia Yap; Leonid Beigelman; Vladimir Serebryany; Jyanwei Liu; Srikonda Sastry; Scott Seiwert; Brad Buckman Journal: Antimicrob Agents Chemother Date: 2016-12-27 Impact factor: 5.191
Authors: Ola Weiland; Gustaf Ahlén; Helmut Diepolder; Maria-Christina Jung; Sepideh Levander; Michael Fons; Iacob Mathiesen; Niranjan Y Sardesai; Anders Vahlne; Lars Frelin; Matti Sällberg Journal: Mol Ther Date: 2013-06-11 Impact factor: 11.454
Authors: Fredrik Holmström; Margaret Chen; Anangi Balasiddaiah; Matti Sällberg; Gustaf Ahlén; Lars Frelin Journal: Sci Rep Date: 2016-05-04 Impact factor: 4.379