Usefulness of combined measurement of serum bile acids and ferritin as additional prognostic markers to predict failure to reach sustained response to antiviral treatment in chronic hepatitis C

The Roles and Pathogenesis Mechanisms of a Number of Micronutrients in the Prevention and/or Treatment of Chronic Hepatitis, COVID-19 and Type-2 Diabetes Mellitus

A trace element is a chemical element with a concentration (or other measures of an amount) that is very low. The essential TEs, such as copper (Cu), selenium (Se), zinc (Zn), iron (Fe) and the electrolyte magnesium (Mg) are among the most commonly studied micronutrients. Each element has been shown to play a distinctive role in human health, and TEs, such as iron (Fe), zinc (Zn) and copper (Cu), are among the essential elements required for the organisms' well-being as they play crucial roles in several metabolic pathways where they act as enzyme co-factors, anti-inflammatory and antioxidant agents. Epidemics of infectious diseases are becoming more frequent and spread at a faster pace around the world, which has resulted in major impacts on the economy and health systems. Different trace elements have been reported to have substantial roles in the pathogenesis of viral infections. Micronutrients have been proposed in various studies as determinants of liver disorders, COVID-19 and T2DM risks. This review article sheds light on the roles and mechanisms of micronutrients in the pathogenesis and prevention of chronic hepatitis B, C and E, as well as Coronavirus-19 infection and type-2 diabetes mellitus. An update on the status of the aforementioned micronutrients in pre-clinical and clinical settings is also briefly summarized.

Changes of Gut-Microbiota-Liver Axis in Hepatitis C Virus Infection

Simple Summary

Gut microbiota alteration is linked to many health disorders including hepatitis C virus (HCV) infection. This dysbiosis in turn impacts the coordination between the gut and the liver that is known as the gut–liver-axis. Here, we discuss the latest findings regarding the changes in gut microbiota structure and functionality post HCV infection and its treatment regimens. In addition, we underline the contribution of the microbiota alterations to HCV associated liver complications.

Abstract

The gut–liver-axis is a bidirectional coordination between the gut, including microbial residents, the gut microbiota, from one side and the liver on the other side. Any disturbance in this crosstalk may lead to a disease status that impacts the functionality of both the gut and the liver. A major cause of liver disorders is hepatitis C virus (HCV) infection that has been illustrated to be associated with gut microbiota dysbiosis at different stages of the disease progression. This dysbiosis may start a cycle of inflammation and metabolic disturbance that impacts the gut and liver health and contributes to the disease progression. This review discusses the latest literature addressing this interplay between the gut microbiota and the liver in HCV infection from both directions. Additionally, we highlight the contribution of gut microbiota to the metabolism of antivirals used in HCV treatment regimens and the impact of these medications on the microbiota composition. This review sheds light on the potential of the gut microbiota manipulation as an alternative therapeutic approach to control the liver complications post HCV infection.

Analysis of bile acids in human biological samples by microcolumn separation techniques: A review

Bile acids are a group of compounds essential for lipid digestion and absorption with a steroid skeleton and a carboxylate side chain usually conjugated to glycine or taurine. Bile acids are regulatory molecules for a number of metabolic processes and can be used as biomarkers of various disorders. Since the middle of the twentieth century, the detection of bile acids has evolved from simple qualitative analysis to accurate quantification in complicated mixtures. Advanced methods are required to characterize and quantify individual bile acids in these mixtures. This article overviews the literature from the last two decades (2000-2020) and focuses on bile acid analysis in various human biological samples. The methods for sample preparation, including the sample treatment of conventional (blood plasma, blood serum, and urine) and unconventional samples (bile, saliva, duodenal/gastric juice, feces, etc.) are shortly discussed. Eventually, the focus is on novel analytical approaches and methods for each particular biological sample, providing an overview of the microcolumn separation techniques, such as high-performance liquid chromatography, gas chromatography, and capillary electrophoresis, used in their analysis. This is followed by a discussion on selected clinical applications.

Prediagnostic concentrations of circulating bile acids and hepatocellular carcinoma risk: REVEAL-HBV and HCV studies

Hepatocellular carcinoma (HCC) is the dominant histologic type of liver cancer, accounting for 75% of cases. Growing evidence suggests that the cross-talk between the gut microbiome and metabolome (ie, gut-liver axis) are related to the development of hepatic inflammation, and ultimately, HCC. Bile acids are metabolites, derived from cholesterol and synthesized in the liver, which may have a critical role in regulation of the gut-liver axis. We investigated whether prediagnostic circulating bile acids were associated with HCC risk, using the Risk Evaluation of Viral Load Elevation and Associated Liver Disease/Cancer (REVEAL)-Hepatitis B Virus (HBV) and REVEAL-Hepatitis C Virus (HCV) cohorts from Taiwan. Fifteen bile acids were quantitated using liquid chromatography, from 185 cases and 161 matched controls in REVEAL-HBV and 96 cases and 96 matched controls in REVEAL-HCV. Odds ratios (ORs) and 95% confidence intervals (CIs) for associations between bile acid levels and HCC were calculated using multivariable-adjusted logistic regression. Higher levels of glycine and taurine conjugated primary bile acids were associated with a 2- to 8-fold increased risk of HBV- (eg, glycocholic acid OR_Q4vsQ1 = 3.38, 95% CI: 1.48-7.71, P_trend < .003) and HCV-related HCC (eg, OR = 8.16, 95% CI: 2.21-30.18, P_trend < .001). However, higher levels of the secondary bile acid deoxycholic acid were inversely associated with HBV-related HCC risk (OR = 0.41, 95% CI: 0.19-0.88, P_trend = .02). Our study provides evidence that higher concentrations of bile acids-specifically, conjugated primary bile acids-are associated with increased HCC risk. However, our study does not support the hypothesis that higher levels of secondary bile acids increase liver cancer risk; indeed, deoxycholic acid may be associated with a decreased HCC risk.

The Role of the Sodium-taurocholate Co-transporting Polypeptide (NTCP) and Bile Salt Export Pump (BSEP) in Related Liver Disease

BACKGROUND

Sodium Taurocholate Co-transporting Polypeptide (NTCP) and Bile Salt Export Pump (BSEP) play significant roles as membrane transporters because of their presence in the enterohepatic circulation of bile salts. They have emerged as promising drug targets in related liver disease.

METHODS

We reviewed the literature published over the last 20 years with a focus on NTCP and BSEP.

RESULTS

This review summarizes the current perception about structure, function, genetic variation, and regulation of NTCP and BSEP, highlights the effects of their defects in some hepatic disorders, and discusses the application prospect of new transcriptional activators in liver diseases.

CONCLUSION

NTCP and BSEP are important proteins for transportation and homeostasis maintenance of bile acids. Further research is needed to develop new models for determining the structure-function relationship of bile acid transporters and screening for substrates and inhibitors, as well as to gain more information about the regulatory genetic mechanisms involved in the processes of liver injury.

The Role of Micronutrients in the Infection and Subsequent Response to Hepatitis C Virus

Micronutrient deficiencies develop for a variety of reasons, whether geographic, socioeconomic, nutritional, or as a result of disease pathologies such as chronic viral infection. As micronutrients are essential for a strong immune response, deficiencies can significantly dampen both the innate and the adaptive arms of antiviral immunity. The innate immune response in particular is crucial to protect against hepatitis C virus (HCV), a hepatotropic virus that maintains chronic infection in up to 80% of individuals if left untreated. While many micronutrients are required for HCV replication, an overlapping group of micronutrients are also necessary to enact a potent immune response. As the liver is responsible for the storage and metabolism of many micronutrients, HCV persistence can influence the micronutrients' steady state to benefit viral persistence both directly and by weakening the antiviral response. This review will focus on common micronutrients such as zinc, iron, copper, selenium, vitamin A, vitamin B12, vitamin D and vitamin E. We will explore their role in the pathogenesis of HCV infection and in the response to antiviral therapy. While chronic hepatitis C virus infection drives deficiencies in micronutrients such as zinc, selenium, vitamin A and B12, it also stimulates copper and iron excess; these micronutrients influence antioxidant, inflammatory and immune responses to HCV.

Serum IP-10 levels and increased DPPIV activity are linked to circulating CXCR3+ T cells in cholestatic HCV patients

BACKGROUND & AIMS

Serum interferon-gamma-inducible protein-10 (IP-10) is elevated in cholestatic liver diseases and predicts response to antiviral therapy in patients with chronic hepatitis C virus (HCV) infection. Dipeptidylpeptidase 4 (DPPIV) cleaves active IP-10 into an inactive form, which inhibits recruitment of CXCR3+ T cells to the liver. In this study the link between IP-10 levels, DPPIV activity in serum and CXCR3+ T cells is analysed in cholestatic and non-cholestatic liver patients.

METHODS

In serum DPPIV activity (by enzymatic assay), IP-10 (by ELISA) and bile acids (BA) (by enzymatic assay) were analysed in 229 naive HCV genotype (GT) 1 patients and in 16 patients with cholestatic liver disease. In a prospective follow-up (FU) cohort of 27 HCV GT 1 patients peripheral CD3+CXCR3+, CD4+CXCR3+ and CD8+CXCR3+ cells were measured by FACS.

RESULTS

In 229 HCV patients serum IP-10 levels correlated positively to DPPIV serum activity. Higher IP-10 levels and DPPIV activity were detected in cholestatic and in cirrhotic HCV patients. Increased IP-10 serum levels were associated with therapeutic non-response to antiviral treatment with pegylated-interferon and ribavirin. In the HCV FU cohort elevated IP-10 serum levels and increased BA were associated with higher frequencies of peripheral CD3+CXCR3+, CD4+CXCR3+ and CD8+CXCR3+ T cells. Positive correlation between serum IP-10 levels and DPPIV activity was likewise validated in patients with cholestatic liver diseases.

CONCLUSIONS

A strong correlation between elevated serum levels of IP-10 and DPPIV activity was seen in different cholestatic patient groups. Furthermore, in cholestatic HCV patients a functional link to increased numbers of peripheral CXCR3+ immune cells could be observed. The source of DPPIV release in cholestatic patients remains open.

Triplex High-Resolution Melting Assay for the Simultaneous Assessment of IFNL3 rs12979860, ABCB11 rs2287622, and RNF7 rs16851720 Genotypes in Chronic Hepatitis C Patients

Chronic hepatitis C (CHC) is a leading cause of liver disease. Despite the improved efficacy of new antivirals, their high costs preclude their adoption in resource-limited settings, where CHC prevalence is highest. We developed a triplex high-resolution melting assay for the simultaneous assessment of three genetic polymorphisms related to the response to treatment and development of advanced fibrosis in CHC: IFNL3 rs12979860, ABCB11 rs2287622, and RNF7 rs16851720. We validated the assay in clinical samples from 130 CHC patients treated with classic therapy. The assay showed excellent reproducibility and 100% accuracy, sensitivity, and specificity against the gold standard Sanger sequencing. When added to routine examination data, genotype information significantly improved their performance for prediction of advanced liver fibrosis and sustained virological response (P = 0.041 and P = 0.011, respectively). Correspondingly, the full models had area under the receiver operating characteristic curve values of 0.842 (95% CI, 0.773-0.911) and 0.921 (95% CI, 0.870-0.972) and integrated discrimination improvements of 7.5% (95% CI, 2.5%-12.5%; P = 0.003) and 11.5% (95% CI, 5.8%-17.2%; P < 0.001), respectively. This is the first report on a diagnostic test for simultaneous genotyping of IFNL3, ABCB11, and RNF7 in CHC patients. Reliable and inexpensive, the assay should provide useful information for the clinical management of CHC, like identification of patients at risk of rapid disease progression or with high chances of response to classic therapy.

Demographic profile, host, disease & viral predictive factors of response in patients with chronic hepatitis C virus infection at a tertiary care hospital in north India

Background & objectives:

Standard of care for chronic hepatitis C (CHC) in India is peginterferon and ribavirin (RBV). The response to treatment in real life stetting is unclear. The objectives of this study were to evaluate the demographic profile and assess the virological response and predictors of response in CHC patients.

Methods:

Consecutive patients with CHC were included in this study. Detailed clinical history, risk factors, and predictive factors of response were noted. Patients were treated with peginterferon α2b (1.5 µg/kg/wk) and RBV (12 mg/kg/day) for 6 to 18 months based on response.

Results:

A total of 211 patients were included in the analysis, mean age 40.6±12.3 yr, 144 (68%) were males and 71 (34%) had compensated cirrhosis. Commonest risk factor for acquiring CHC was previous transfusion and surgery (51%). Genotype 3 (72%) was most common followed by genotype 1 (23%). Overall sustained virologic response (SVR) was 64 per cent [95% CI 57.1%-70.4%]. The SVR was 66.5 per cent [95% CI 58.34-73.89%] for genotype 3 and 61.2 per cent [95% CI 46.23 to 74.80%] for genotype 1. Non-cirrhotics had better SVR rates compared to cirrhotics (76 vs 41%, P<0.001). On multivariate analysis, BMI ≥23 kg/m², HOMA-IR ≥2, compliance (≤80%), and fibrosis >2 were predictors of low SVR.

Interpretation & conclusions:

Genotype 3 was the commonest HCV genotype. The commonest source of infection was previous transfusion and surgery. SVR rates for genotypes 3 were better than genotype 1 patients. Predictors of non-response were high BMI, insulin resistance, significant fibrosis and inadequate compliance.

Hepatitis C virus-associated pruritus: Etiopathogenesis and therapeutic strategies

In addition to its contributing role in the development of chronic liver diseases, chronic hepatitis C virus (HCV) infection is associated with extrahepatic manifestations, particularly, cutaneous-based disorders including those with pruritus as a symptom. Pruritus is frequently associated with the development of chronic liver diseases such as cholestasis and chronic viral infection, and the accumulation of bile acids in patients’ sera and tissues as a consequence of liver damage is considered the main cause of pruritus. In addition to their role in dietary lipid absorption, bile acids can trigger the activation of specific receptors, such as the G protein-coupled bile acid receptor (GPBA/ TGR5). These types of receptors are known to play a crucial role in the modulation of the systemic actions of bile acids. TGR5 expression in primary sensory neurons triggers the activation of the transient receptor potential vanilloid 1 (TRPV1) leading to the induction of pruritus by an unknown mechanism. Although the pathologic phenomenon of pruritus is common, there is no uniformly effective therapy available. Understanding the mechanisms regulating the occurrence of pruritus together with the conduction of large-scale clinical and evidence-based studies, may help to create a standard treatment protocol. This review focuses on the etiopathogenesis and treatment strategies of pruritus associated with chronic HCV infection.

Design of β-CD-surfactant complex-coated liquid crystal droplets for the detection of cholic acid via competitive host-guest recognition

β-CD-C14TAB complex-coated 5CB droplets are designed by the adsorption of β-CD-C14TAB complexes at the 5CB/aqueous interface. We show that the 5CB droplets can be used as an optical probe for the selective detection of cholic acid in aqueous solution containing uric acid and urea via competitive host-guest recognition.

Sorting out cirrhosis: mechanisms of non-response to hepatitis C therapy

Although cirrhosis has long been recognized as an important negative predictor of treatment response for hepatitis C virus (HCV) therapy, the mechanisms underlying this association remain relatively poorly understood. Treatment has progressed rapidly with the introduction of highly effective all-oral therapies, with promising outcomes even in patients with advanced cirrhosis. However, even with the new therapies, it is clear that patients with cirrhosis require special attention. Efficacy continues to be somewhat reduced compared to non-cirrhotic patients and safety is an important concern. In this review, we explore the reasons for treatment non-response in patients with cirrhosis. We focus on how cirrhosis impacts on four important areas including drug delivery, drug uptake and metabolism, immune responses and drug toxicity with examples from the clinical and basic literature. Fortunately, as treatment continues to progress, many of the challenges of treating patients with cirrhosis will become less and less problematic.

Tailoring the surface of liquid crystal droplets with chitosan/surfactant complexes for the selective detection of bile acids in biological fluids

The surface of 5CB droplets dispersed in aqueous solution is tailored by the adsorption of CHI/SC₁₄S complexes at the 5CB/aqueous interface. The CHI/SC₁₄S complex-coated 5CB droplets can be used as an optical probe to detect CA in biological fluids without dilution.

Intrahepatic cholestasis in common chronic liver diseases

BACKGROUND AND OBJECTIVE

Cholestasis represents the consequence of impaired bile formation and decrease in bile flow, generally classified as extra- and intrahepatic. Cholestasis is the pivotal hallmark of the so-called primary cholestatic liver diseases but may also emerge in other forms of chronic liver injury. The aim now was to summarise the current state of knowledge on intrahepatic cholestasis related to chronic liver diseases.

METHODS

For this overview on intrahepatic cholestasis in chronic liver disorders other than the 'classic' cholestatic liver diseases, selected references were retrieved by literature search in MEDLINE and textbooks were reviewed. All articles were selected that discussed pathophysiological and clinical aspects of intrahepatic cholestasis in the context of alcoholic liver disease, nonalcoholic fatty liver disease, chronic hepatitis B and C virus infections as well as drug-induced and granulomatous liver diseases. Titles referring to primary biliary cirrhosis and sclerosing cholangitis were excluded.

RESULTS AND CONCLUSIONS

Dependent on the aetiology, intrahepatic cholestasis is present at variable frequencies and in different disease stages in chronic liver diseases. Cholestasis secondary to chronic liver injury may denote a severe disease course and development of end-stage liver disease or specific disease variants. These findings indicate that 'secondary intrahepatic cholestasis' (SIC) can occur in the natural course of chronic liver diseases other than the primary cholestatic diseases, in particular in the setting of advanced disease progression.

Bile acids: Metabolism, physiology and clinical significance

Enterohepatic circulation of bile acids can promote lipid digestion and absorption, prevent gallstone formation, and increase the secretion of bile. Measurement of serum bile acids can be used to predict the progression from acute hepatitis to chronic hepatitis and evaluate the degree of inflammation and fibrosis in patients with chronic hepatitis and the degree of portal hypertension and severe hepatitis. Serum bile acids are also an early and sensitive predictor of the relief of biliary obstruction in patients with obstructive jaundice. In addition, serum bile acids can be used for the diagnosis of inflammatory bowel disease, intrahepatic cholestasis during pregnancy, congenital biliary tract disease, and liver transplantation.

Farnesoid X receptor targeting for hepatitis C: study protocol for a proof-of-concept trial

OBJECTIVE

To test the modulation of farnesoid X receptor activity on the replication of hepatitis C virus in chronically infected patients.

METHODS

This is a proof-of-concept trial that was approved by the ex-French Agency for the Safety of Health Products (ex-Afssaps [currently ANSM]) and an ethics committee. It has started in January 2010. This one-arm, open-label study examines the safety and efficacy of the oral administration of guggulsterone. The main outcome measure will be the assessment of blood viral loads.

RESULTS

We planned to enrol 15 genotype 1-infected patients that failed a first-line therapy.

CONCLUSION

We think guggulsterone might be an effective therapeutic option for HCV genotype 1 patients who do not respond well to first-line therapy.

Host genetic variants in the pathogenesis of hepatitis C

Direct-acting antiviral drugs (DAAs) are currently replacing antiviral therapy for Hepatitis C infection. Treatment related side effects are even worse and the emergence of resistant viruses must be avoided because of the direct-antiviral action. Altogether it remains a challenge to take treatment decisions in a clinical setting with cost restrictions. Genetic host factors are hereby essential to implement an individualized treatment concept. In recent years results on different genetic variants have been published with a strong association with therapy response, fibrosis and treatment-related side effects. Polymorphisms of the IL28B gene were identified as accurate predictors for therapy response and spontaneous clearance of HCV infection and are already used for diagnostic decisions. For RBV-induced side effects, such as hemolytic anemia, associations to genetic variants of inosine triphosphatase (ITPA) were described and different SLC28 transporters for RBV-uptake have been successfully analyzed. Fibrosis progression has been associated with variants of Vitamin D receptor (VDR) and ABCB11 (bile salt export pump). Cirrhotic patients especially have a high treatment risk and low therapy response, so that personalized antiviral treatment is mandatory. This review focuses on different host genetic variants in the pathogenesis of Hepatitis C at the beginning of a new area of treatment.

Bile acids specifically increase hepatitis C virus RNA-replication

Background

Hepatitis C virus (HCV) patients with high serum levels of bile acids (BAs) respond poorly to IFN therapy. BAs have been shown to increase RNA-replication of genotype 1 but not genotype 2a replicons. Since BAs modulate lipid metabolism including lipoprotein secretion and as HCV depends on lipids and lipoproteins during RNA-replication, virus production and cell entry, BAs may affect multiple steps of the HCV life cycle. Therefore, we analyzed the influence of BAs on individual steps of virus replication.

Methods

We measured replication of subgenomic genotype (GT) 1b and 2a RNAs as well as full-length GT2a genomes in the presence of BAs using quantitative RT-PCR and luciferase assays. Cell entry was determined using HCV pseudoparticles (HCVpp). Virus assembly and release were quantified using a core-specific ELISA. Replicon chimeras were employed to characterize genotype-specific modulation of HCV by BAs. Lunet CD81/GFP-NLS-MAVS cells were used to determine infection of Con1 particles.

Results

BAs increased RNA-replication of GT1b replicons up to 10-fold but had no effect on subgenomic GT2a replicons both in Huh-7 and HuH6 cells. They did not increase viral RNA translation, virus assembly and release or cell entry. Lowering replication efficiency of GT2a replicons rendered them susceptible to stimulation by BAs. Moreover, replication of full length GT1b with or without replication enhancing mutations and GT2a genomes were also stimulated by BAs.

Conclusions

Bile acids specifically enhance RNA-replication. This is not limited to GT1, but also holds true for GT2a full length genomes and subgenomic replicons with low replication capacity. The increase of HCV replication by BAs may influence the efficacy of antiviral treatment in vivo and may improve replication of primary HCV genomes in cell culture.

The role of bile acid retention and a common polymorphism in the ABCB11 gene as host factors affecting antiviral treatment response in chronic hepatitis C

The outcome of hepatitis C virus (HCV) infection and the likelihood of a sustained virological response (SVR) to antiviral therapy depends on both viral and host characteristics. In vitro studies demonstrated that bile acids (BA) interfere with antiviral interferon effects. We investigate the influence of plasma BA concentrations and an ABCB11 polymorphism associated with lower transporter expression on viral load and SVR. Four hundred and fifty-one Caucasian HCV-patients treated with PEG-interferon and ribavirin were included in the study. ABCB11 1331T>C was genotyped, and plasma BA levels were determined. The 1331C allele was slightly overrepresented in HCV-patients compared to controls. In HCV-patients, a significant difference between patients achieving SVR vs non-SVR was observed for HCV-2/3 (5 vs 9 μm; P=0.0001), while median BA levels in HCV-1 were marginally elevated. Normal BA levels <8 μm were significantly associated with SVR (58.3%vs 36.3%; OR 2.48; P=0.0001). This difference was significant for HCV-2/3 (90.7%vs 67.6%; P=0.002) but marginal in HCV-1 (38.7%vs 27.8%; P=0.058). SVR rates were equivalent between ABCB11 genotypes for HCV-1, but increased for HCV-2/3 (TT 100%vs CC 78%; OR 2.01; P=0.043). IL28B genotype had no influence on these associations. No correlation between BA levels and HCV RNA was detected for any HCV genotype. The higher allelic frequency of ABCB11 1331C in HCV-patients compared to controls may indirectly link increased BA to HCV chronicity. Our data support a role for BA as host factor affecting therapy response in HCV-2/3 patients, whereas a weaker association was found for HCV-1.

Nuclear receptors as new perspective for the management of liver diseases

Nuclear receptors (NRs) are ligand-activated transcription factors that act as sensors for a broad range of natural and synthetic ligands and regulate several key hepatic functions including bile acid homeostasis, bile secretion, lipid and glucose metabolism, as well as drug deposition. Moreover, NRs control hepatic inflammation, regeneration, fibrosis, and tumor formation. Therefore, NRs are key for understanding the pathogenesis and pathophysiology of a wide range of hepatic disorders. Finally, targeting NRs and their alterations offers exciting new perspectives for the treatment of liver diseases.

Genetic variations of bile salt transporters as predisposing factors for drug-induced cholestasis, intrahepatic cholestasis of pregnancy and therapeutic response of viral hepatitis

INTRODUCTION

Drug-induced cholestasis, intrahepatic cholestasis of pregnancy and viral hepatitis are acquired forms of liver disease. Cholestasis is a pathophysiologic state with impaired bile formation and subsequent accumulation of bile salts in hepatocytes. The bile salt export pump (BSEP) (ABCB11) is the key export system for bile salts from hepatocytes.

AREAS COVERED

This article provides an introduction into the physiology of bile formation followed by a summary of the current knowledge on the key bile salt transporters, namely, the sodium-taurocholate co-transporting polypeptide NTCP, the organic anion transporting polypeptides (OATPs), BSEP and the multi-drug resistance protein 3. The pathophysiologic consequences of altered functions of these transporters, with an emphasis on molecular and genetic aspects, are then discussed.

EXPERT OPINION

Knowledge of the role of hepatocellullar transporters, especially BSEP, in acquired cholestasis is continuously increasing. A common variant of BSEP (p.V444A) is now a well-established susceptibility factor for acquired cholestasis and recent evidence suggests that the same variant also influences the therapeutic response and disease progression of viral hepatitis C. Studies in large independent cohorts are now needed to confirm the relevance of p.V444A. Genome-wide association studies should lead to the identification of additional genetic factors underlying cholestatic liver disease.

Determination of total bile acid levels using a thick-film screen-printed Ir/C sensor for the detection of liver disease

An electrochemical sensor, based on thick-film screen-printed Ir/C working and counter electrodes, was developed for the detection of total bile acid concentration in a physiological fluid for potential patient management in patients with liver disease. Current electrochemical methods of detecting total bile acid levels involve the use of potentials greater than +0.45 V, versus an Ag/AgCl reference electrode, and require a selectively permeable membrane. The proposed detection method did not require any membrane and used a potential of +0.27 V versus Ag/AgCl. This biosensor used 3-alpha-hydroxysteroid dehydrogenase (3alpha-HSD) (EC 1.1.1.50) immobilized on the thick-film screen-printed working electrode to detect the enzymatically generated NADH. The production of the NADH resulted from the reaction of the enzyme with bile acids such as sodium cholate, taurocholic and taurochenodeoxycholic acid, which could then be used to quantify the total bile acid. Constant potential measurements showed that this biosensor had good linear performance over a 0-200 microM concentration range in the phosphate buffer and the bovine serum. The sensor performance was also examined at different temperatures and pH conditions. This sensor prototype could be used for single use, disposable detection of total bile acids, extending its applicability for simple and early detection of liver disease.

Treatment predictors of a sustained virologic response in hepatitis B and C

Treatment predictors are important tools for the management of therapy in patients with chronic hepatitis B and C virus (HBV, HCV) infection. In chronic hepatitis B, several pretreatment parameters have been identified for prediction of virologic response to interferon alfa-based antiviral therapies or treatment with polymerase inhibitors. In interferon alfa and pegylated interferon alfa-treated patients, low baseline HBV DNA concentrations, HBV genotype A (B), and high baseline ALT levels are significantly associated with treatment response. In patients treated with nucleos(t)ide analogues, low baseline HBV DNA but not viral genotype is positively associated with virologic response. During treatment the best predictor of response is HBV DNA kinetics. Early viral suppression is associated with favourable virologic response and reduced risk for subsequent resistance mutations. For the current standard treatment with pegylated interferon alfa and ribavirin in patients with chronic hepatitis C, infection with HCV genotypes 2 and 3, baseline viral load below 400,000-800,000 IU/ml, Asian and Caucasian ethnicity, younger age, low GGT levels, absence of advanced fibrosis/cirrhosis, and absence of steatosis in the liver have been identified as independent pretreatment predictors of a sustained virologic response. After initiation of treatment, initial viral decline with undetectable HCV-RNA at week 4 of therapy (RVR) is the best predictor of sustained virologic response independent of HCV genotype.

Enhancement of genotype 1 hepatitis C virus replication by bile acids through FXR

BACKGROUND/AIMS

Hepatitis C virus (HCV) infected patients with high serum levels of bile acids (BAs) usually fail to respond to antiviral therapy. Besides, BAs are essential factors for replication of the porcine enteric calicivirus by inhibiting interferon signaling. The role of BAs on HCV RNA replication was thus assessed.

METHODS

BAs and other compounds were tested using an HCV-replication model containing a luciferase reporter gene.

RESULTS

BAs, especially chenodeoxycholate and deoxycholate, up-regulated genotype 1 HCV RNA replication by more than tenfold. Only free but not conjugated BAs were active, suggesting that their effect was mediated by a nuclear receptor. Only farnesoid X receptor (FXR) ligands stimulated HCV replication while FXR silencing and FXR antagonism by guggulsterone blocked the up-regulation induced by BAs. Furthermore, guggulsterone alone inhibited basal level of HCV replication by tenfold. Modulation of HCV replication by FXR ligands occurred in the same proportion in presence or absence of type I interferon, suggesting a mechanism of action independent of this control of viral replication. However, BAs or guggulsterone did not affect replication of genotype 2a-JFH1.

CONCLUSIONS

Exposure to routinely measured concentrations of BAs increases HCV replication by a novel mechanism involving activation of the nuclear receptor FXR.

ME3738 protects against lithocholic acid-induced hepatotoxicity, which is associated with enhancement of biliary bile acid and cholesterol output

ME3738 (22beta-methoxyolean-12-ene-3beta, 24(4beta)-diol), a derivative of soyasapogenol, attenuates liver disease in several models of chronic liver inflammation. In the present study, we have investigated a protective effect of ME3738 in a typical bile acid-induced cholestatic liver model, lithocholate (LCA) feeding mouse. Co-administration of ME3738 resulted in decreases in plasma alanine aminotransferase (ALT) and alkaline phosphatase (ALP) activities and hepatic bile acid level, and increases in biliary outputs of bile acid and cholesterol, as compared with the results in mice treated with LCA alone. LCA sulfation by hydroxysteroid sulfotransferase 2a and hydroxylation have been reported to be involved in protection against LCA-induced hepatotoxicity. ME3738-treatment, however, had no clear influence on the hydroxysteroid sulfotransferase 2a protein level and LCA 6alpha-, 6beta- and 7alpha-hydroxylase activities, but increased biliary cholesterol output. Cholate (CA)-treatment has been shown to induce hepatotoxicity in farnesoid X receptor-null mice, which is scarcely dependent on bile acid sulfation and hydroxylation but associated with decreased biliary bile acid output. Co-administration of ME3738 decreased the ALT and ALP activities and hepatic bile acid level, and increased biliary outputs of bile acid and cholesterol in farnesoid X receptor-null mice, as compared with the results in the mice treated with CA. Moreover, a clear correlation between biliary outputs of cholesterol and bile acid was observed in these two bile acid-induced hepatotoxicity mouse models. These results suggest that ME3738 protects against bile acid-induced hepatotoxicity through increased biliary bile acid output that is not related to bile acid metabolism but associated with cholesterol output.