IOT-022

The liver, and more precisely hepatocytes, can be infected by several hepatotropic viruses, including HBV, HDV, HCV and HEV, with chronic infection leading to end-stage liver diseases. Since no in vitro model allowing multi-infections with the four viruses is reported, limited data are available on their interplay as well as on the potential cross-reactivity of antivirals in multi-infection cases. The aim of our study was to set up such a model.

HuH7.5-NTCP cells were cultured with 2% DMSO (dimethyl sulfoxide) for 1 week to allow partial differentiation into hepatocytes (dHuH7.5-NTCP) before infection with the different viruses and treatment with known antiviral molecules.

We observed increased expression of liver specific transcripts and production of ApoB containing VLDL in dHuH7.5-NTCP cells and replication of HBV, HDV, HCV and HEV for at least 4 weeks after mono or multiple infections. We recapitulated the known antiviral effect of sofosbuvir on HCV and HEV (>90% reduction in the levels of intracellular viral RNAs, p <0.0005) and of IFN-α on HCV, HEV and HDV (80% reduction in the levels of intracellular viral RNAs, p <0.0005). Besides its already described antiviral effect on HBV and HDV, we observed that GW4064, a farnesoid X receptor (FXR) agonist, also strongly inhibited HEV replication (85 to 95% reduction in the levels of intracellular HEV RNAs, p <0.0005). Using HEV-infected HuHep mice, we confirmed the antiviral effect of vonafexor, an FXR agonist, that is currently being tested clinically against HBV/HDV.

We set-up the first in vitro model allowing multi-infections with hepatitis viruses that can be used for broad drug screening and highlighted FXR ligands as potential broad-acting antivirals.

Hepatitis virus infections caused by HBV, HCV, HDV, and HEV represent a global health threat. Treatment options remain limited, notably due to the lack of knowledge about molecular virus-host interactions. Moreover, the interplay between these four viruses in the context of co-infections remains unknown. In this study, we report the first in vitro system that allows for mono and multi-infections with these four viruses and characterize the broad antiviral activity of farnesoid X receptor agonists, paving the way for the development of new strategies for viral cure.

Patients with low phospholipid-associated cholelithiasis may suffer from recurrent biliary symptoms and complications despite cholecystectomy and ursodeoxycholic acid therapy. Recently, beneficial clinical effects of treatment with the potent Farnesoid X receptor (i.e. bile salt receptor) agonist obeticholic acid in combination with ursodeoxycholic acid were reported in this patient group. In contrast, other studies reported more gallstone-related events and increased cholesterol saturation indices in gallbladder biles during obeticholic acid monotherapy. We here provide an in-depth review on solubilization and crystallization of cholesterol in bile, including all relevant physico-chemical aspects of cholesterol gallstone pathogenesis. We offer an explanation that reconciles seemingly contradictory data in previous publications. We propose that, due to the well-known inhibition of intra-hepatic bile salt synthesis from cholesterol by Farnesoid X receptor stimulation, biliary bile salt concentrations decrease during obeticholic acid therapy. As a result, biliary cholesterol solubilization shifts from mixed micelles into cholesterol-phospholipid vesicles, with inhibited cholesterol crystallization despite increased cholesterol saturation index (the latter takes only micellar cholesterol solubilization into account). We suggest that obeticholic acid has a lithoprotective effect, provided that increased bile salt hydrophobicity from obeticholic acid (a quite hydrophobic bile salt that is secreted into bile) is prevented by concomitant ursodeoxycholic acid therapy. We also suggest future directions for research into the role of obeticholic acid and other Farnesoid X receptor agonists to improve the prospects of low phospholipid-associated cholelithiasis patients and other gallstone patients with persisting biliary problems after cholecystectomy. In conclusion, obeticholic acid may enhance lithoprotective effects of ursodeoxycholic acid.