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BACKGROUND & AIMS: HDV superinfection of chronically HBV-infected patients is the most aggressive form of chronic viral hepatitis, with an accelerated progression towards fibrosis/cirrhosis and increased risk of liver failure, hepatocellular carcinoma, and death. While HDV infection is not susceptible to available direct anti-HBV drugs, suboptimal responses are obtained with interferon-α-based therapies, and the number of investigational drugs remains limited. We therefore analyzed the effect of several innate immune stimulators on HDV replication in infected hepatocytes. METHODS: We used in vitro models of HDV and HBV infection based on primary human hepatocytes (PHHs) and the non-transformed HepaRG cell line that are relevant to explore new innate immune therapies. RESULTS: We describe here, for the first time, anti-HDV effects of Pam3CSK4 and BS1, agonists of Toll-like receptor (TLR)-1/2, and the lymphotoxin-ß receptor (LTßR), respectively. Both types of agonists induced dose-dependent reductions of total intracellular HDV genome and antigenome RNA and of HDV protein levels, without toxicity in cells monoinfected with HDV or co/superinfected with HBV. Moreover, both molecules negatively affected HDV progeny release and strongly decreased their specific infectivity. The latter effect is particularly important since HDV is thought to persist in humans through constant propagation. CONCLUSIONS: Immune-modulators inducing NF-κB pathways in hepatocytes can inhibit HDV replication and should be further evaluated as a possible therapeutic approach in chronically HBV/HDV-infected patients. LAY SUMMARY: Hepatitis delta virus causes the most severe form of viral hepatitis. Despite positive recent developments, effective treatments remain a major clinical need. Herein, we show that immune-modulators that trigger the NF-κB pathways could be effective for the treatment of hepatitis delta infections.
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Background & Aims: Non-absorbable inhibitors of the apical sodium-dependent bile acid transporter (ASBT; also called ileal bile acid transporter [IBAT]) are recently approved or in clinical development for multiple cholestatic liver disorders and lead to a reduction in pruritus and (markers for) liver injury. Unfortunately, non-absorbable ASBT inhibitors (ASBTi) can induce diarrhoea or may be ineffective if cholestasis is extensive and largely precludes intestinal excretion of bile acids. Systemically acting ASBTi that divert bile salts towards renal excretion may alleviate these issues. Methods: Bile duct ligation (BDL) was performed in ASBT-deficient (ASBT knockout [KO]) mice as a model for chronic systemic ASBT inhibition in obstructive cholestasis. Co-infusion of radiolabelled taurocholate and inulin was used to quantify renal bile salt excretion after BDL. In a second (wild-type) mouse model, a combination of obeticholic acid (OCA) and intestine-restricted ASBT inhibition was used to lower the bile salt pool size before BDL. Results: After BDL, ASBT KO mice had reduced plasma bilirubin and alkaline phosphatase compared with wild-type mice with BDL and showed a marked reduction in liver necrotic areas at histopathological analysis, suggesting decreased BDL-induced liver damage. Furthermore, ASBT KO mice had reduced bile salt pool size, lower plasma taurine-conjugated polyhydroxylated bile salt, and increased urinary bile salt excretion. Pretreatment with OCA + ASBTi in wild-type mice reduced the pool size and greatly improved liver injury markers and liver histology. Conclusions: A reduced bile salt pool at the onset of cholestasis effectively lowers cholestatic liver injury in mice. Systemic ASBT inhibition may be valuable as treatment for cholestatic liver disease by lowering the pool size and increasing renal bile salt output even under conditions of minimal faecal bile salt secretion. Lay summary: Novel treatment approaches against cholestatic liver disease (resulting in reduced or blocked flow of bile) involve non-absorbable inhibitors of the bile acid transport protein ASBT, but these are not always effective and/or can cause unwanted side effects. In this study, we demonstrate that systemic inhibition/inactivation of ASBT protects mice against developing severe cholestatic liver injury after bile duct ligation, by reducing bile salt pool size and increasing renal bile salt excretion.
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BACKGROUND: Primary human hepatocytes offer the best human in vitro model for studies on human liver cell metabolism. Investigators use a variety of different media supplements and matrix biocoatings and the type of culture system used may influence the outcome. OBJECTIVES: To optimize in vitro conditions for primary human hepatocytes with regard to bile acid synthesis. METHODS: Human hepatocytes were isolated and cultured on collagen type I or EHS matrigel in cell media with or without dexamethasone. The glucocorticoid receptor (GR) antagonist RU486 was used to elucidate the involvement of GR. RESULTS: Hepatocytes cultured on EHS matrigel produced more bile acids and expressed higher levels of cholesterol 7α-hydroxylase (CYP7A1) than cells cultured on rat tail collagen. Supplementation with dexamethasone increased the formation of cholic acid (CA) and decreased chenodeoxycholic acid formation. In line with these results, the mRNA expression of sterol 12α-hydroxylase (CYP8B1) increased following dexamethasone treatment. Surprisingly, the mRNA expression of CYP7A1 and CYP27A1 was not increased to the same extent. By using the GR antagonist RU486, we concluded that CYP8B1 induction is mediated via a GR-independent pathway. An altered expression of retinoid-related orphan receptor (ROR) α and ROR α target gene Glucose-6-phosphatase (G6Pase) suggests that ROR α signaling may regulate CYP8B1 expression. CONCLUSION: Primary human hepatocytes have an increased bile acid synthesis rate when cultured on matrigel as compared to collagen. Exposure to glucocorticoid hormones stimulates the expression of CYP8B1, leading to an increased formation of CA and alteration of the bile acid composition. The effect is most likely mediated through a GR-independent pathway, possibly through ROR α.