Functional innate immunity restricts Hepatitis C Virus infection in induced pluripotent stem cell–derived hepatocytes

Abstract

Knowledge of activation and interplay between the hepatitis C virus (HCV) and the hosts’ innate immunity is essential to understanding the establishment of chronic HCV infection. Human hepatoma cell lines, widely used as HCV cell culture system, display numerous metabolic alterations and a defective innate immunity, hindering the detailed study of virus-host interactions. Here, we analysed the suitability of induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (iHLCs) as a physiologically relevant model to study HCV replication in vitro. Density gradients and triglyceride analysis revealed that iHLCs secreted very-low density lipoprotein (VLDL)-like lipoproteins, providing a putative platform for bona fide lipoviroparticles. iHLCs supported the full HCV life cycle, but in contrast to Huh7 and Huh7.5 cells, replication and viral RNA levels decreased continuously. Following HCV infection, interferon-stimulated gene (ISG)-expression significantly increased in iHLCs, whereas induction was almost absent in Huh7/7.5 cells. However, IFNα-stimulation equally induced ISGs in iHLCs and hepatoma cells. JAK-STAT pathway inhibition increased HCV replication in mature iHLCs, but not in Huh7 cells. Additionally, HCV replication levels where higher in STAT2-, but not STAT1-knockdown iHLCs. Our findings support iHLCs as a suitable model for HCV-host interaction regarding a functional innate immunity and lipoprotein synthesis.

Stem cell-derived polarized hepatocytes

“…3b). In agreement with a recent study 18 , this suggests that HLCs in general, unlike hepatoma cells, have a functional VLDL biosynthesis pathway. Importantly, pol-HLCs secreted higher levels of lipoproteins than nonpol-HLCs, and these lipoproteins were selectively secreted into the basolateral compartment ( Fig.…”

“…2). We and others have previously shown that even nonpol-HLCs can synthesize and release ALB, ApoB100 and ApoE 17,18 . Here, we found that pol-HLCs released the majority of these cargos directionally from their basolateral membrane ( Supplementary Figs.…”

Efficient acute and chronic infection of stem cell-derived hepatocytes by hepatitis C virus

“…Modulation of the JAK/STAT pathway has been discussed previously as a way to improve viral replication in HLCs 16–18. Here, we monitored in detail the induction of innate immunity and its influence, on the complete replication cycle over extended periods.…”

“…Upon inoculation with cell culture-derived HCV (HCVcc) containing the JFH1 (Gt2a) replication machinery,15 HLCs yield detectable intracellular HCV RNA replication, but only limited and transient production of infectious progeny viruses. It is generally assumed that active innate immunity is responsible for this acute HCV infection 16–18…”

“…Among previously described IRGs with anti-HCV action are the PRRs MDA5 and RIG-I,26 ISG 1527 and MXA 28. Modulation of the JAK/STAT signalling pathway in HLCs has been previously described in order to improve HEV14 and HCV16–18 infection, but with conflicting results reported 17. Another approach to improve viral replication is to use HCVcc virus populations, selected for higher viral replication in Huh7-derived cell lines.…”