Hepatitis C virus selectively perturbs the distal cholesterol synthesis pathway in a genotype-specific manner

The CH24H metabolite, 24HC, blocks viral entry by disrupting intracellular cholesterol homeostasis

Cholesterol-24-hydroxylase (CH24H or Cyp46a1) is a reticulum-associated membrane protein that plays an irreplaceable role in cholesterol metabolism in the brain and has been well-studied in several neuro-associated diseases in recent years. In the present study, we found that CH24H expression can be induced by several neuroinvasive viruses, including vesicular stomatitis virus (VSV), rabies virus (RABV), Semliki Forest virus (SFV) and murine hepatitis virus (MHV). The CH24H metabolite, 24-hydroxycholesterol (24HC), also shows competence in inhibiting the replication of multiple viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). 24HC can increase the cholesterol concentration in multivesicular body (MVB)/late endosome (LE) by disrupting the interaction between OSBP and VAPA, resulting in viral particles being trapped in MVB/LE, ultimately compromising VSV and RABV entry into host cells. These findings provide the first evidence that brain cholesterol oxidation products may play a critical role in viral infection.

Infection with the hepatitis C virus causes viral genotype-specific differences in cholesterol metabolism and hepatic steatosis

Lipids play essential roles in the hepatitis C virus (HCV) life cycle and patients with chronic HCV infection display disordered lipid metabolism which resolves following successful anti-viral therapy. It has been proposed that HCV genotype 3 (HCV-G3) infection is an independent risk factor for hepatocellular carcinoma and evidence suggests lipogenic proteins are involved in hepatocarcinogenesis. We aimed to characterise variation in host lipid metabolism between participants chronically infected with HCV genotype 1 (HCV-G1) and HCV-G3 to identify likely genotype-specific differences in lipid metabolism. We combined several lipidomic approaches: analysis was performed between participants infected with HCV-G1 and HCV-G3, both in the fasting and non-fasting states, and after sustained virological response (SVR) to treatment. Sera were obtained from 112 fasting patients (25% with cirrhosis). Serum lipids were measured using standard enzymatic methods. Lathosterol and desmosterol were measured by gas-chromatography mass spectrometry (MS). For further metabolic insight on lipid metabolism, ultra-performance liquid chromatography MS was performed on all samples. A subgroup of 13 participants had whole body fat distribution determined using in vivo magnetic resonance imaging and spectroscopy. A second cohort of (non-fasting) sera were obtained from HCV Research UK for comparative analyses: 150 treatment naïve patients and 100 non-viraemic patients post-SVR. HCV-G3 patients had significantly decreased serum apoB, non-HDL cholesterol concentrations, and more hepatic steatosis than those with HCV-G1. HCV-G3 patients also had significantly decreased serum levels of lathosterol, without significant reductions in desmosterol. Lipidomic analysis showed lipid species associated with reverse cholesterol transport pathway in HCV-G3. We demonstrated that compared to HCV-G1, HCV-G3 infection is characterised by low LDL cholesterol levels, with preferential suppression of cholesterol synthesis via lathosterol, associated with increasing hepatic steatosis. The genotype-specific lipid disturbances may shed light on genotypic variations in liver disease progression and promotion of hepatocellular cancer in HCV-G3.

The Role of Metabolic Dysfunction in T-Cell Exhaustion During Chronic Viral Infection

T cells are important components of adaptive immunity that protect the host against invading pathogens during infection. Upon recognizing the activation signals, naïve and/or memory T cells will initiate clonal expansion, trigger differentiation into effector populations and traffic to the inflamed sites to eliminate pathogens. However, in chronic viral infections, such as those caused by human immunodeficiency virus (HIV), hepatitis B and C (HBV and HCV), T cells exhibit impaired function and become difficult to clear pathogens in a state known as T-cell exhaustion. The activation and function persistence of T cells demand for dynamic changes in cellular metabolism to meet their bioenergetic and biosynthetic demands, especially the augmentation of aerobic glycolysis, which not only provide efficient energy generation, but also fuel multiple biochemical intermediates that are essential for nucleotide, amino acid, fatty acid synthesis and mitochondria function. Changes in cellular metabolism also affect the function of effectors T cells through modifying epigenetic signatures. It is widely accepted that the dysfunction of T cell metabolism contributes greatly to T-cell exhaustion. Here, we reviewed recent findings on T cells metabolism under chronic viral infection, seeking to reveal the role of metabolic dysfunction played in T-cell exhaustion.

LDL particle size and antioxidant HDL function improve after sustained virological response in patients with chronic HCV

HCV infection is associated with an increased incidence of cardiovascular (CV) events. Mechanisms underlying this association remain unknown. In our study, twenty HCV patients (median age 60.5 years, 65% male and 80% with cirrhosis) were evaluated prior, during and after direct-acting antiviral treatment. Ninety percent of patients achieved sustained virological response (SVR). Significant changes were observed in LDL particle size index, measured by LDL-C/apoB ratio, which increased after treatment (p = 0.023). In addition, HDL antioxidant capacity improved gradually from 34.4% at baseline to 42.4% at 4 weeks (p = 0.011), 65.9% at end of treatment EOT (p = 0.002) and remained elevated at 12-week (p = 0.001) after EOT compared to baseline values. Our findings suggest that a shift to a less atherogenic lipid profile may be a possible mechanism associated with CV risk reduction in patients with HCV infection achieving SVR.

Cholesterol-25-Hydroxylase Suppresses Seneca Valley Virus Infection via Producing 25-Hydroxycholesterol to Block Adsorption Procedure

Cholesterol-25-hydroxylase (CH25H) is a membrane protein associated with endoplasmic reticulum, and it is an interferon-stimulated factor regulated by interferon. CH25H catalyzes cholesterol to produce 25-hydroxycholesterol (25HC) by adding a second hydroxyl to the 25th carbon atom of cholesterol. Recent studies have shown that both CH25H and 25HC could inhibit the replication of many viruses. In this study, we found that ectopic expression of CH25H in HEK-293T and BHK-21 cell lines could inhibit the replication of Seneca Valley virus (SVV) and that there was no species difference. On the other hand, the knockdown of CH25H could enhance the replication of SVV in HEK-293T and BHK-21 cells, indicating the importance of CH25H. To some extent, the CH25H mutant without hydroxylase activity also lost its ability to inhibit SVV amplification. Further studies demonstrated that 25HC was involved in the entire life cycle of SVV, especially in repressing its adsorption process. This study reveals that CH25H exerts the advantage of innate immunity mainly by producing 25HC to block virion adsorption.

Metabolic and cardiovascular complications after virological cure in hepatitis C: What awaits beyond

The association between chronic hepatitis C (CHC) infection and extrahepatic manifestations (EHMs), particularly cardiometabolic diseases, has been extensively examined. However, there has still been insufficient evaluation for these EHMs after virological cure. Several multidirectional mechanisms have been proposed explaining the ability of hepatitis C virus (HCV) developing EHMs, cardiometabolic ones, as well as the effect of antiviral therapy to resolve these EHMs. Data on these manifestations after achieving sustained virologic response (SVR) are still conflicting. However, current evidence suggests that reversal of hepatic steatosis and its coexistent hypocholesterolemia after successful viral eradication led to unfavorable lipid profile, which increases cardiovascular disease (CVD) risk. Additionally, most observations showed that metabolic alterations, such as insulin resistance and diabetes mellitus (DM), undergo some degree of reduction after viral clearance. These changes seem HCV-genotype dependent. Interferon-based antiviral therapy and direct acting antiviral drugs were shown to minimize incidence of DM. Large epidemiological studies that investigated the effect of SVR on CVD showed great discrepancies in terms of results, with predominant findings indicating that CVD events decreased in patients with SVR compared to non-responders or untreated ones. In this review, we present a summary of the current knowledge regarding extrahepatic sequelae of CHC following SVR, which may have an impact on healthcare providers’ clinical practice.

Multifaceted Functions of CH25H and 25HC to Modulate the Lipid Metabolism, Immune Responses, and Broadly Antiviral Activities

With the frequent outbreaks of emerging infectious diseases in recent years, an effective broad-spectrum antiviral drug is becoming an urgent need for global public health. Cholesterol-25-hydroxylase (CH25H) and its enzymatic products 25-hydroxycholesterol (25HC), a well-known oxysterol that regulates lipid metabolism, have been reported to play multiple functions in modulating cholesterol homeostasis, inflammation, and immune responses. CH25H and 25HC were recently identified as exerting broadly antiviral activities, including upon a variety of highly pathogenic viruses such as human immunodeficiency virus (HIV), Ebola virus (EBOV), Nipah virus (NiV), Rift Valley fever virus (RVFV), and Zika virus (ZIKV). The underlying mechanisms for its antiviral activities are being extensively investigated but have not yet been fully clarified. In this study, we summarized the current findings on how CH25H and 25HC play multiple roles to modulate cholesterol metabolism, inflammation, immunity, and antiviral infections. Overall, 25HC should be further studied as a potential therapeutic agent to control emerging infectious diseases in the future.

Cholesterol 25-hydroxylase inhibits encephalomyocarditis virus replication through enzyme activity-dependent and independent mechanisms

Cholesterol-25-hydroxylase (CH25 H) is a reticulum-associated membrane protein induced by an important interferon-stimulating gene (ISG) and can significantly inhibit some virus replication. But the effect of CH25H on encephalomyocarditis virus (EMCV) is still not clear. In this study, we found that EMCV infection increases significantly the endogenous CH25H expression in BHK-21 and N2a cells. CH25H and cholesterol catalytic oxidation product 25-hydroxycholesterol (25HC) obviously inhibits EMCV infection by inhibiting the viral penetration. But the CH25H mutant lacking hydroxylase activity repairs the ability to inhibit the viral replication. Meanwhile, β-cyclodextrin crystalline as a cholesterol inhibitor significantly decreases the viral replication. In addition, CH25H can selectively interact and degrade the viral RNA-Dependent RNA Polymerase-3D protein by independent on the association of proteasome, lysosome and caspase manner. It provides new insights into the interplay mechanisms between CH25H and non-enveloped single-stranded positive RNA viruses.

Fatty Acids Regulate Porcine Reproductive and Respiratory Syndrome Virus Infection via the AMPK-ACC1 Signaling Pathway

Lipids play a crucial role in the replication of porcine reproductive and respiratory syndrome virus (PRRSV), a porcine virus that is endemic throughout the world. However, little is known about the effect of fatty acids (FAs), a type of vital lipid, on PRRSV infection. In this study, we found that treatment with a FA biosynthetic inhibitor significantly inhibited PRRSV propagation, indicating the necessity of FAs for optimal replication of PRRSV. Further study revealed that 5′-adenosine monophosphate (AMP)-activated protein kinase (AMPK), a key kinase antagonizing FA biosynthesis, was strongly activated by PRRSV and the pharmacological activator of AMPK exhibited anti-PRRSV activity. Additionally, we found that acetyl-CoA carboxylase 1 (ACC1), the first rate-limiting enzyme in the FA biosynthesis pathway, was phosphorylated (inactive form) by PRRSV-activated AMPK, and active ACC1 was required for PRRSV proliferation, suggesting that the PRRSV infection induced the activation of the AMPK–ACC1 pathway, which was not conducive to PRRSV replication. This work provides new evidence about the mechanisms involved in host lipid metabolism during PRRSV infection and identifies novel potential antiviral targets for PRRSV.

T cell metabolism in chronic viral infection

T cells are a fundamental component of the adaptive immune response in the context of both acute and chronic viral infection. Tight control over the metabolic processes within T cells provides an additional level of immune regulation that is interlinked with nutrient sensing and the continued balancing of co-stimulatory and co-inhibitory signals. Underpinning T cell responsiveness for viral control are a number of phenotypic and functional adaptations ensuring adequate nutrient uptake and their utilization. T cells responding to persistent viral infections often exhibit a profile associated with immune cell exhaustion and a dysregulated metabolic profile, driven by a combination of chronic antigenic stimulation and signals from the local microenvironment. Understanding alterations in these metabolic processes provides an important basis for immunotherapeutic strategies to treat persistent infections.

Virus Genotype-Dependent Transcriptional Alterations in Lipid Metabolism and Inflammation Pathways in the Hepatitis C Virus-infected Liver

Despite advances in antiviral therapy, molecular drivers of Hepatitis C Virus (HCV)-related liver disease remain poorly characterised. Chronic infection with HCV genotypes (1 and 3) differ in presentation of liver steatosis and virological response to therapies, both to interferon and direct acting antivirals. To understand what drives these clinically important differences, liver expression profiles of patients with HCV Genotype 1 or 3 infection (n = 26 and 33), alcoholic liver disease (n = 8), and no liver disease (n = 10) were analysed using transcriptome-wide microarrays. In progressive liver disease, HCV genotype was the major contributor to altered liver gene expression with 2151 genes differentially expressed >1.5-fold between HCV Genotype 1 and 3. In contrast, only 6 genes were altered between the HCV genotypes in advanced liver disease. Induction of lipogenic, lipolytic, and interferon stimulated gene pathways were enriched in Genotype 1 injury whilst a broad range of immune-associated pathways were associated with Genotype 3 injury. The results are consistent with greater lipid turnover in HCV Genotype 1 patients. Moreover, the lower activity in inflammatory pathways associated with HCV genotype 1 is consistent with relative resistance to interferon-based therapy. This data provides a molecular framework to explain the clinical manifestations of HCV-associated liver disease.

Metabolic programming of macrophage functions and pathogens control

Macrophages (Mφ) are central players in mediating proinflammatory and immunomodulatory functions. Unchecked Mφ activities contribute to pathology across many diseases, including those caused by infectious pathogens and metabolic disorders. A fine balance of Mφ responses is crucial, which may be achieved by enforcing appropriate bioenergetics pathways. Metabolism serves as the provider of energy, substrates, and byproducts that support differential Mφ characteristics. The metabolic properties that control the polarization and response of Mφ remain to be fully uncovered for use in managing infectious diseases. Here, we review the various metabolic states in Mφ and how they influence the cell function.

Hepatitis C virus genotype 3: clinical features, current and emerging viral inhibitors, future challenges

Hepatitis C virus (HCV) represents a global burden on healthcare that affects over 150 million people worldwide. In the past, HCV genotype 3 was considered difficult to treat relative to other genotypes. Genotype 3 has been associated with a higher rate of complications, including fatty liver disease, fibrosis, hepatocellular carcinoma and mortality. However, with the advent of first- and second-generation direct-acting antivirals, genotype 3 can be treated effectively. Additionally, these new drugs are well tolerated by patients and have significantly fewer side effects compared to ribavirin and interferon-based regimens. However, while great strides have been made in overcoming biological barriers, our next challenge lies in overcoming economic and financial obstacles if we are to eradicate HCV genotype 3. Herein, we review the clinical features associated with HCV genotype 3, current and emerging treatment regimens, and challenges associated with treatment.

Vitamin D deficiency in hepatitis C virus infection: what is old? what is new?

In the past few years, a growing body of clinical evidence has highlighted the risk of vitamin D deficiency in patients with chronic hepatitis C and that vitamin D levels are associated with the course of hepatitis C virus (HCV) infection, adverse effects, and treatment response to peginterferon/ribavirin. Recently, studies have found that vitamin D status is related to drug resistance and increased risk of infection in patients with liver cirrhosis. Vitamin D-related gene polymorphisms have been found to explain the interactions between vitamin D deficiency and HCV infection, offering a new perspective toward understanding the current problems such as the development of insulin resistance and racial differences in sustained virological response. Studies have been conducted to determine whether vitamin D supplementation as an adjuvant yields a better result compared with traditional HCV treatment. Here, we provide a brief review of the past and present knowledge of vitamin D in HCV infection.

Vitamin D and the Liver-Correlation or Cause?

Vitamin D is becoming increasingly accepted as an important physiological regulator outside of its classical role in skeletal homeostasis. A growing body of evidence connects vitamin D with hepatic disease. This review summarises the role of vitamin D in liver homeostasis and disease and discusses the therapeutic potential of vitamin D-based treatments to protect against hepatic disease progression and to improve response to treatment. While pre-clinical experimental data is promising, clinical trials around liver diseases have mostly been under-powered, and further studies will be required to clarify whether vitamin D or vitamin D analogues have beneficial effects on liver disease.

Recovery of lipid metabolic alterations in hepatitis C patients after viral clearance: Incomplete restoration with accelerated ω-oxidation

BACKGROUND

How hepatitis C virus (HCV)-associated lipid metabolic alterations recover after sustained virological response (SVR) remains elusive.

OBJECTIVE

The aforementioned recovery pattern was investigated.

METHODS

In a prospective cohort study of 438 chronic hepatitis C (CHC) patients with SVR after anti-HCV therapy, 164 sex- and age-matched genotype I (G1) and G2 patients underwent paired-serum liquid chromatography-tandem mass spectrometry analyses before and 24 weeks after therapy. Subjects without CHC served as controls (n = 100).

RESULTS

CHC patients had lower baseline lipid levels than controls. Among CHC patients, pre-therapy total cholesterol levels were positively associated with HCV RNA levels; G1 patients had higher pre-therapy HCV RNA levels than G2 patients. Repeated measures analysis of variance of CHC patients showed that lathosterol, lanosterol, total hydroxysphingomyelin, and total phosphatidylcholines levels, and total dicarboxyacylcarnitine/total acylcarnitine (indicators of ω-oxidation) and pre-β-lipoprotein ratios elevated 24 weeks after therapy compared with the levels before therapy. Levels of total lysophosphatidylcholines and α- and β-lipoprotein ratios decreased. Subgroup analyses showed elevated 7-dehydrocholesterol and lanosterol levels, particularly in G2 and male patients, who had broader spectra of altered phosphatidylcholines and acylcarnitines than G1 and female patients, respectively. Compared with controls, CHC patients had higher post-therapy levels of total lysophosphatidylcholines and hydroxysphingomyelins and ratios of total dicarboxyacylcarnitines/total acylcarnitines but lower cholesterol levels.

CONCLUSIONS

At 24 weeks after therapy, accelerated cholesterol biosynthesis, hepatic lipid export, ω-oxidation, and decreased systemic inflammation were noted in CHC patients with SVR, with greater efficiency in G2 and male patients. Regardless, HCV-associated lipid metabolic alterations required >24 weeks for restoration or were incompletely reversible after SVR.

Avasimibe: A novel hepatitis C virus inhibitor that targets the assembly of infectious viral particles

Direct-acting antivirals (DAAs), which target hepatitis C virus (HCV) proteins, have exhibited impressive efficacy in the management of chronic hepatitis C. However, the concerns regarding high costs, drug resistance mutations and subsequent unexpected side effects still call for the development of host-targeting agents (HTAs) that target host factors involved in the viral life cycle and exhibit pan-genotypic antiviral activity. Given the close relationship between lipid metabolism and the HCV life cycle, we investigated the anti-HCV activity of a series of lipid-lowering drugs that have been approved by government administrations or proven safety in clinical trials. Our results showed that avasimibe, an inhibitor of acyl coenzyme A:cholesterol acyltransferase (ACAT), exhibited marked pan-genotypic inhibitory activity and superior inhibition against HCV when combined with DAAs. Moreover, avasimibe significantly impaired the assembly of infectious HCV virions. Mechanistic studies demonstrated that avasimibe induced downregulation of microsomal triglyceride transfer protein expression, resulting in reduced apolipoprotein E and apolipoprotein B secretion. Therefore, the pan-genotypic antiviral activity and clinically proven safety endow avasimibe exceptional potential as a candidate for combination therapy with DAAs. In addition, the discovery of the antiviral properties of ACAT inhibitors also suggests that inhibiting the synthesis of cholesteryl esters might be an additional target for the therapeutic intervention for chronic HCV infection.

Cholesterol 25-hydroxylase is an interferon-inducible factor that protects against porcine reproductive and respiratory syndrome virus infection

Porcine reproductive and respiratory syndrome virus (PRRSV), a single-stranded, positive-sense RNA virus of the Arteriviridae family, has become a global health threat for swine. Cholesterol 25-hydroxylase (CH25H) is an enzyme that catalyzes oxidation of cholesterol to 25-hydroxycholesterol (25HC). The purpose of this study was to explore the antiviral activity of CH25H against PRRSV infection. We found that CH25H was induced by interferon-α and PRRSV in Marc-145 monkey kidney cells. In addition, CH25H and 25HC significantly inhibited PRRSV infection by preventing virus entry. A CH25H mutant that exhibited decreased catalytic activity had an antiviral effect against PRRSV. Treatment with 25HC pre-infection or post-infection significantly inhibited PRRSV infection in primary porcine alveolar macrophages. Our results reveal that CH25H is an interferon-stimulated gene and its production of 25HC can be used as a natural antiviral agent to combat PRRSV infection.

Cholesterol 25-Hydroxylase Inhibits Porcine Reproductive and Respiratory Syndrome Virus Replication through Enzyme Activity-Dependent and -Independent Mechanisms

Cholesterol 25-hydroxylase (CH25H) has recently been identified as a host restriction factor that exerts antiviral effects by catalyzing the production of 25-hydroxycholesterol (25HC). CH25H can be rapidly induced upon infection with some viruses. Porcine reproductive and respiratory syndrome virus (PRRSV), an arterivirus, has ranked among the most important swine pathogens since it was discovered in the late 1980s. In this study, we found that PRRSV infection significantly downregulated the expression of CH25H in cells by a so-far unknown mechanism, suggesting that CH25H exerts antiviral activity against PRRSV. Indeed, overexpression of CH25H inhibited PRRSV replication, whereas knockdown of CH25H by short interfering RNA (siRNA) promoted PRRSV infection. The anti-PRRSV effect of 25HC operates via inhibition of viral penetration. Interestingly, a CH25H mutant (CH25H-M) lacking hydroxylase activity still inhibited PRRSV infection. Screening using a yeast two-hybrid system followed by coimmunoprecipitation and immunofluorescence colocalization analyses confirmed that both CH25H and CH25H-M interact with the nonstructural protein 1 alpha (nsp1α) of PRRSV. Unexpectedly, the expression of nsp1α decreased following coexpression with CH25H or CH25H-M. Detailed analyses demonstrated that CH25H/CH25H-M could degrade nsp1α through the ubiquitin-proteasome pathway and that site K169 in the nsp1α protein is the key site of ubiquitination. Taken together, our findings demonstrate that CH25H restricts PRRSV replication by targeting viral penetration as well as degrading nsp1α, revealing a novel antiviral mechanism used by CH25H.IMPORTANCE PRRSV has been a continuous threat to the global swine industry, and current vaccines are insufficient to provide sustainable control. CH25H has been found to exert a broad antiviral effect; thus, it is an attractive target for the development of anti-PRRSV drugs. Here, we demonstrate that CH25H is an interferon-stimulated gene that is highly expressed in porcine alveolar macrophages. CH25H exerts its anti-PRRSV effect not only via the production of 25HC to inhibit viral penetration but also by degrading viral protein through the ubiquitin-proteasome pathway, suggesting that CH25H is a candidate for the development of antiviral therapeutics. However, PRRSV infection appears to actively decrease CH25H expression to promote viral replication, highlighting the complex game between PRRSV and its host.

Interferon-independent antiviral activity of 25-hydroxycholesterol in a teleost fish

Oxysterols are a family of cholesterol oxygenated derivatives with diverse roles in many biological activities and have recently been linked with the induction of a cellular antiviral state. The antiviral effects of 25-hydroxycholesterol (25HC) extend to several mammalian enveloped and non-enveloped viruses. It has been reported that the expression of the gene encoding cholesterol 25-hydroxylase (CH25H) is induced by interferons (IFNs). In this work, five ch25h genes were identified in the zebrafish (Danio rerio) genome. The ch25h genes showed different tissue expression patterns and differed in their expression after immune stimulation with lipopolysaccharide (LPS), polyinosinic:polycytidylic acid (PolyI:C) and Spring Viremia Carp Virus (SVCV). Only one of the 5 genes, ch25hb, was overexpressed after the administration of the treatments. Synteny and phylogenetic analyses revealed that ch25hb is the putative homolog of mammalian Ch25h in zebrafish, while the remaining zebrafish ch25h genes are products of duplications within the teleost lineage. Interestingly, its modulation was not mediated by type I IFNs, contrasting previous reports on mammalian orthologs. Nevertheless, in vivo overexpression of ch25hb in zebrafish larvae significantly reduced mortality after SVCV challenge. Viral replication was also negatively affected by 25HC administration to the zebrafish cell line ZF4. In conclusion, the interferon-independent antiviral role of 25HC was extended to a non-mammalian species for the first time, and dual activity that both protects the cells and interacts with the virus cannot be discarded.

Metabolic Manifestations of Hepatitis C Virus: Diabetes Mellitus, Dyslipidemia

Metabolic disorders are common in patients with chronic hepatitis C virus (HCV) infection. Epidemiologic and clinical data indicate an overprevalence of lipids abnormalite, steatosis, insuline resistance (IR) and diabetes mellitus in HCV patients, suggesting that HCV itself may interact with glucido-lipidic metabolism. HCV interacts with the host lipid metabolism by several mechanisms leading to hepatic steatosis and hypolipidemia which are reversible after viral eradication. Liver and peripheral IR are HCV genotype/viral load dependent and improved after viral eradication. This article examines examine the relationship between HCV, lipid abnormalities, steatosis, IR, and diabetes and the pathogenic mechanisms accounting for these events in HCV-infected patients.

A Comparative Analysis of Serum Lipids in Patients with Chronic Hepatitis C, Nonalcoholic Fatty Liver Disease and Healthy Controls

Serum lipids abnormalities are widespread among patients with chronic hepatitis C (CHC), but the impact of concomitant hepatic steatosis [steatosis, nonalcoholic steatosis (NAS)], as well as distinctions between it and nonalcoholic fatty liver disease (NAFLD) are not well established yet. The aim of the study was to assess and compare the serum lipids in patients with genotype 1 CHC with and without steatosis, those with NAFLD, and healthy controls (HC). A total of 1010 subjects were included in this study: 366 CHC genotype 1 patients with steatosis (n = 227) and without steatosis (n = 139), 403 NAFLD patients, and 241 HC without fatty liver or other disease, matched for age and gender. Serum lipids, body mass index (BMI), components of metabolic syndrome (MS), and serum insulin levels were evaluated. In addition serum lipoprotein (a) [Lp(a)] levels were studied in 112 CHC and 80 NAFLD patients. The mean levels of total cholesterol, LDL-cholesterol and triglycerides (Tg) were higher and the mean levels of HDL-cholesterol were lower in all patients with steatosis (CHC and NAFLD) than in CHC cases without steatosis (p < 0.05 and p = 0.001, resp.). Higher prevalence and severity of lipid abnormalities, including Lp(a), were observed in patients with NAFLD than in those with CHC (p < 0.001). No difference was found between CHC patients without steatosis and HC. Higher prevalence and grade of glucose metabolic abnormalities were also observed in patients with NAFLD and CHC with steatosis than in cases without steatosis (p < 0.05 and p = 0.001, resp.). Lipid and glucose metabolic abnormalities in patients with CHC were dependent on steatosis. CHC with steatosis and NAFLD were associated with insulin resistant type dyslipidemia, with total cholesterol and LDL-cholesterol being generally lower in CHC.

Hepatitis C Virus-Genotype 3: Update on Current and Emergent Therapeutic Interventions

PURPOSE OF REVIEW

Direct-acting antiviral agents (DAAs) have markedly improved the prognosis of hepatitis C virus (HCV)-genotype 3 (GT3), a highly prevalent infection worldwide. However, in patients with hepatic fibrosis, cirrhosis, or hepatocellular carcinoma (HCC), GT3 infection presents a treatment challenge compared with other genotypes. The dependence of the HCV life cycle on host lipid metabolism suggests the possible utility of targeting host cellular factors for combination anti-HCV therapy. We discuss current and emergent DAA regimens for HCV-GT3 treatment. We then summarize recent research findings on the reliance of HCV entry, replication, and virion assembly on host lipid metabolism.

RECENT FINDINGS

Current HCV treatment guidelines recommend the use of daclatasvir plus sofosbuvir (DCV/SOF) or sofosbuvir plus velpatasvir (SOF/VEL) for the management of GT3 based upon clinical efficacy [≥88% overall sustained virological response (SVR)] and tolerability. Potential future DAA options, such as SOF/VEL co-formulated with GS-9857, also look promising in treating cirrhotic GT3 patients. However, HCV resistance to DAAs will likely continue to impact the therapeutic efficacy of interferon-free treatment regimens. Disruption of HCV entry by targeting required host cellular receptors shows potential in minimizing HCV resistance and broadening therapeutic options for certain subpopulations of GT3 patients. The use of cholesterol biosynthesis and transport inhibitors may also improve health outcomes for GT3 patients when used synergistically with DAAs. Due to the morbidity and mortality associated with HCV-GT3 infection compared to other genotypes, efforts should be made to address current limitations in the therapeutic prevention and management of HCV-GT3 infection.

Is there an association between vitamin D and liver fibrosis in patients with chronic hepatitis C?

BACKGROUND

- Vitamin D is known for its immunomodulatory, anti-inflammatory and antifibrotic properties, which are quite relevant in the pathogenesis and treatment of many causes of chronic liver disease.

OBJECTIVE

- This study aimed to evaluate the association between serum vitamin D levels and the histopathological findings in patients with chronic hepatitis C virus infection.

METHODS

- Cross-sectional study composed of patients with chronic hepatitis C. All patients underwent vitamin D 25 dosage and anthropometric data analysis. Liver biopsy was performed in a maximum 36-month period before inclusion in the study.

RESULTS

- Of the 74 patients included in the study, 45 (60.8%) were women, mean age was 57.03±9.24 years, and 63 (85.1%) were white. No association was observed between the serum levels of vitamin D and inflammatory activity (P=0.699) nor with the degree of liver fibrosis (P=0.269).

CONCLUSION

- In this study, no association was observed between vitamin D and inflammatory activity, as well as the degree of liver fibrosis, in patients with chronic hepatitis C.

Genotype 3 Infection: The Last Stand of Hepatitis C Virus

Hepatitis C virus (HCV) represents a significant global disease burden, with an estimated 130-150 million people worldwide living with chronic HCV infection. Within the six major clinical HCV genotypes, genotype 3 represents 22-30% of all infection and is described as a unique entity with higher rates of steatosis, faster progression to cirrhosis, and higher rates of hepatocellular carcinoma. Hepatic steatosis in the setting of hepatitis C genotype 3 (HCV-3) is driven by viral influence on three major pathways: microsomal triglyceride transfer protein, sterol regulatory element-binding protein-1c, and peroxisome proliferator-associated receptor-α. Historically with direct-acting antivirals, the rates of cure for HCV-3 therapies lagged behind the other genotypes. As current therapies for HCV-3 continue to close this gap, it is important to be cognizant of common drug interactions such as acid-suppressing medication and amiodarone. In this review, we discuss the rates of steatosis in HCV-3, the mechanisms behind HCV-3-specific steatosis, and current and future therapies.

Oral Combination Therapies for Hepatitis C Virus Infection: Successes, Challenges, and Unmet Needs

The current standard of care for the treatment of hepatitis C virus (HCV) consists of interferon-free direct-acting antiviral (DAA) regimens, including combinations of DAAs and fixed-dose combination pills. DAAs for HCV are likely to be heralded as one of medicine's greatest advancements. Viral eradication rates are pushing 100% for many HCV-infected populations, including patients with HIV/HCV coinfection, decompensated cirrhosis, liver and kidney transplants, and end-stage liver disease. We highlight the greatest successes of combination DAA therapies, discuss the ongoing challenges, and identify the remaining patient subgroups with unmet medical needs.

Roles of the Mevalonate Pathway and Cholesterol Trafficking in Pulmonary Host Defense

The mevalonic acid synthesis pathway, cholesterol, and lipoproteins play fundamental roles in lung physiology and the innate immune response. Recent literature investigating roles for cholesterol synthesis and trafficking in host defense against respiratory infection was critically reviewed. The innate immune response and the cholesterol biosynthesis/trafficking network regulate one another, with important implications for pathogen invasion and host defense in the lung. The activation of pathogen recognition receptors and downstream cellular host defense functions are critically sensitive to cellular cholesterol. Conversely, microorganisms can co-opt the sterol/lipoprotein network in order to facilitate replication and evade immunity. Emerging literature suggests the potential for harnessing these insights towards therapeutic development. Given that >50% of adults in the U.S. have serum cholesterol abnormalities and pneumonia remains a leading cause of death, the potential impact of cholesterol on pulmonary host defense is of tremendous public health significance and warrants further mechanistic and translational investigation.

Genotype specific peripheral lipid profile changes with hepatitis C therapy

AIM

To evaluate magnitude/direction of changes in peripheral lipid profiles in patients undergoing direct acting therapy for hepatitis C by genotype.

METHODS

Mono-infected patients with hepatitis C were treated with guideline-based DAAs at a university-based liver clinic. Patient characteristics and laboratory values were collected before and after the treatment period. Baseline demographics included age, ethnicity, hypertension, diabetes, hyperlipidemia, treatment regimen, and fibrosis stage. Total cholesterol (TCHOL), high density lipoprotein (HDL), low density lipoprotein (LDL), triglycerides (TG), and liver function tests were measured prior to treatment and ETR. Changes in lipid and liver function were evaluated by subgroups with respect to genotype. Mean differences were calculated for each lipid profile and liver function component (direction/magnitude). The mean differences in lipid profiles were then compared between genotypes for differences in direction/magnitude. Lipid profile and liver function changes were evaluated with Levene’s test and student’s t test. Mean differences in lipid profiles were compared between genotypes using ANOVA, post hoc analysis via the Bonferroni correction or Dunnett T3.

RESULTS

Three hundred and seventy five patients enrolled with 321 (85.6%) achieving sustained-viral response at 12 wk. 72.3% were genotype 1 (GT1), 18.1% genotype 2 (GT2), 9.7% genotype 3 (GT3). Baseline demographics were similar. Significant change in lipid profiles were seen with GT1 and GT3 (ΔGT1, p and ΔGT3, p), with TCHOL increasing (+5.3, P = 0.005 and +16.1, P < 0.001), HDL increasing (+12.5, P < 0.001 and +7.9, P = 0.038), LDL increasing (+7.4, P = 0.058 and +12.5, P < 0.001), and TG decreasing (-5.9, P = 0.044 and -9.80 P = 0.067). Among genotypes (ΔGT1 v. ΔGT2 v. ΔGT3, ANOVA), significant mean differences were seen with TCHOL (+5.3 v. +0.1 v. +16.1, P = 0.017) and HDL (+12.3 v. +2 v. +7.9, P = 0.040). Post-hoc, GT3 was associated with a greater increase in TCHOL than GT1 and GT2 (P = 0.028 and P = 0.019).

CONCLUSION

Successful DAA therapy results in increases in TCHOL, LDL, and HDL and decrease in TG, particularly in GT1/GT3. Changes are most pronounced in GT3.

Recovery of pan-genotypic and genotype-specific amino acid alterations in chronic hepatitis C after viral clearance: transition at the crossroad of metabolism and immunity

Recovery of amino acid (AA) metabolism and the associated clinical implications in chronic hepatitis C (CHC) patients with sustained virological response (SVR) following anti-hepatitis C virus (HCV) therapy remains elusive. A prospective cohort study was conducted on 222 CHC patients with SVR. Eighty-two age-matched male genotype 1 (G1) and G2 patients underwent paired serum metabolomics analyses with liquid chromatography-tandem mass spectrometry to examine AAs before and 24 weeks after anti-HCV therapy. Before anti-HCV therapy, G1 patients had a higher HCV RNA level than G2 patients. Twenty-four weeks post-therapy versus pre-therapy, repeated-measures ANOVA showed that the levels of alanine aminotransferase and most AAs decreased while those of lipids, glutamine and putrescine increased in CHC patients. The methionine sulfoxide/methionine ratio decreased, while the asymmetric dimethylarginine/arginine, glutamine/glutamate, citrulline/arginine, ornithine/arginine, kynurenine/tryptophan, tyrosine/phenylalanine and Fisher's ratios increased. Genotype-specific subgroup analyses showed that valine and serotonin/tyrosine increased in G1 and that kynurenine and tyrosine/phenylalanine increased and sarcosine decreased in G2 patients. Viral clearance in CHC patients pan-genotypically restored fuel utilization by decelerating the tricarboxylic acid cycle. Following improvement in liver function, the urea, nitric oxide, methionine, and polyamine cycles were accelerated. The cardiometabolic risk attenuated, but the augmented kynurenine pathway activity could increase the oncogenesis risk. The trends in neurotransmitter formation differed between G1 and G2 patients after SVR. Moreover, the HCV-suppressing effect of valine was evident in G1 patients; with the exception of prostate cancer, the oncogenesis risk increased, particularly in G2 patients, at least within 24 weeks post-anti-HCV therapy.

Second generation direct-acting antivirals - Do we expect major improvements?

The rapid progress in the development of direct-acting antiviral agents for hepatitis C has allowed the vast majority of patients to receive all oral therapy that will eliminate their virus. The success of the new regimens has led many to question the need for further developments in this field. Major improvements in drugs for hepatitis C are unlikely but we predict incremental improvements in the next few years. We hope that the next generation of drugs will address the unresolved issues for patients with genotype 3 infection where current treatments are still not entirely satisfactory and we anticipate improvements in the management of patients with renal failure. Shorter duration treatments, perhaps with novel modes of action, may allow simplified 'one-dose' treatments that will greatly expand our ability to treat patients who have difficulty accessing current services and we anticipate that the clinical community will better define the patients with advanced disease who will benefit from therapy prior to liver transplantation.

Effect of antiviral therapy for HCV on lipid levels

BACKGROUND

HCV has complex interactions with human lipid metabolism leading to down regulation of cholesterol levels. Interferon (IFN) therapy has been shown to decrease cholesterol even further. With the availability of second-generation direct-acting antiviral agents (DAA) the effect of suppressing and eliminating HCV on lipid metabolism warrants reevaluation.

METHODS

Prospective German multicentre cohort on HCV- and HIV-HCV-infected patients treated with direct-antiviral agents (GECCO). Lipids were assessed at baseline, during and after therapy. Wilcoxon test corrected for multiple testing was used.

RESULTS

For the analysis, 520 patients with chronic hepatitis C were available. Patients with chronic hepatitis C were treated as follows: sofosbuvir (SOF)/pegylated IFN (PEG-IFN)/ribavirin (RBV; HCV=34, HIV-HCV=36), SOF/RBV (HCV=47, HIV-HCV=16), SOF/simeprevir (HCV=9, HCV-HIV=2), SOF/daclatasvir +/- RBV (HCV=27, HIV-HCV=47), SOF/ledipasvir +/- RBV (HCV=147, HCV-HIV=100) and ombitasvir/paritaprevir/ritonavir +/- dasabuvir +/- RBV (2D, HCV=2, HCV-HIV=6; 3D, HCV=39, HCV-HIV=8). On treatment there was a statistically significant increase in total cholesterol for any IFN-free DAA regimen, which was maintained after end of therapy. Changes of total cholesterol were driven by changes in low-density lipoprotein cholesterol, whereas high-density lipoprotein cholesterol remained unchanged. In contrast, total cholesterol decreased on SOF/PEG-IFN/RBV and increased after end of therapy above baseline levels. Triglycerides increased during treatment with SOF/PEG-IFN/RBV, but not on DAA-only regimens.

CONCLUSIONS

Suppressing and eliminating HCV with IFN-free DAA regimens increased cholesterol levels, but had no effect on triglycerides. In contrast IFN-based therapy decreased cholesterol and increased triglycerides during treatment and led to increases in cholesterol after achieving sustained virological response.

Correlation between vitamin D levels and apoptosis in geriatric patients infected with hepatitis C virus genotype 4

Background

Vitamin D levels play a pivotal role in most biological processes and differ according to age. A deficiency of vitamin D in chronic hepatitis C (CHC) patients has been shown to be linked with the severity of liver fibrosis, but little is known about the mechanism of this association.

Objective

In this study, we evaluate the potential interrelation between vitamin D levels, oxidative stress, and apoptosis, based on liver fibrosis in geriatric patients infected with hepatitis C virus (HCV) genotype 4.

Subjects and methods

A total of 120 adult individuals aged 30–68 years were recruited in this study. Of these, 20 healthy subjects (15 men and five women) with a mean age of 48.3±6.1 years were selected as controls, and 100 patients with a mean age of 47.8±4.9 years with chronic HCV (CHC) who had undergone liver biopsy (80 men and 20 women) were included in this study. Based on liver radiographic (computed tomography, magnetic resonance imaging) and histological Metavir system analyses, the CHC patients were classified into three groups: asymptomatic CHC carriers (n=30), fibrosis (n=25), and cirrhosis (n=45). HCV RNA, HCV genotypes, inflammatory cytokines AFP and TNFα, 25-hydroxyvitamin D (25[OH]D) levels, apoptotic markers single-stranded DNA (ssDNA) and soluble Fas (sFas), and oxidative stress markers nitric oxide (NO) and total antioxidant capacity (TAC) were estimated by using molecular, immunoassay, and colorimetric techniques.

Results

Approximately 30% of the study population (n=30) were diagnosed as asymptomatic CHC carriers, and 70% of the study population (n=70) had severe fibrosis; these were classified into fibrosis and cirrhosis. There was a significant reduction in 25(OH)D levels and TAC activity, along with an increase in levels of NO, AFP, TNFα, ssDNA, and sFas in fibrosis and cirrhosis subjects compared with those of asymptomatic CHC carriers and health controls. The deficiency in 25(OH)D levels correlated positively with sFas, ssDNA, AFP, TNFα, NO, and TAC, and negatively with age, sex, liver function, body mass index, homeostatic model assessment – insulin resistance, HCV RNA, and viral load. Significant intercorrelation was reported between serum 25(OH)D concentrations and apoptotic and oxidative markers, which suggested progression of liver pathogenesis and fibrogenesis via oxidative and apoptotic mechanisms.

Conclusion

The data showed that vitamin D status was significantly correlated with pathogenesis and fibrogenesis of the liver in geriatric patients infected with HCV genotype 4. The deficiency in 25(OH)D levels was shown to have a pivotal role in the pathogenesis of liver via apoptotic, oxidative stress, and inflammatory mechanistic pathways. The data point to adequate vitamin D levels being recommended for a good response to treatment strategies, especially in older CHC patients.

Metabolic alterations and hepatitis C: From bench to bedside

In addition to causing cirrhosis and hepatocellular carcinoma, hepatitis C virus (HCV) is thought to cause hypolipidemia, hepatic steatosis, insulin resistance, metabolic syndrome, and diabetes. The viral life cycle of HCV depends on cholesterol metabolism in host cells. HCV core protein and nonstructural protein 5A perturb crucial lipid and glucose pathways, such as the sterol regulatory element-binding protein pathway and the protein kinase B/mammalian target of rapamycin/S6 kinase 1 pathway. Although several lines of transgenic mice expressing core or full HCV proteins exhibit hepatic steatosis and/or dyslipidemia, whether they completely reflect the metabolic alterations in humans with HCV infection remains unknown. Many cross-sectional studies have demonstrated increased prevalences of metabolic alterations and cardiovascular events in patients with chronic hepatitis C (CHC); however, conflicting results exist, primarily due to unavoidable individual variations. Utilizing anti-HCV therapy, most longitudinal cohort studies of CHC patients have demonstrated the favorable effects of viral clearance in attenuating metabolic alterations and cardiovascular risks. To determine the risks of HCV-associated metabolic alterations and associated complications in patients with CHC, it is necessary to adjust for crucial confounders, such as HCV genotype and host baseline glucose metabolism, for a long follow-up period after anti-HCV treatment. Adipose tissue is an important endocrine organ due to its release of adipocytokines, which regulate lipid and glucose metabolism. However, most data on HCV infection and adipocytokine alteration are inconclusive. A comprehensive overview of HCV-associated metabolic and adipocytokine alterations, from bench to bedside, is presented in this topic highlight.

Dysregulation of distal cholesterol biosynthesis in association with relapse and advanced disease in CHC genotype 2 and 3 treated with sofosbuvir and ribavirin

BACKGROUND & AIMS

Hepatitis C virus (HCV) modulates host lipid metabolism for its replication and lifecycle. Our aims were to assess changes in the serum lipid and distal (post-squalene) cholesterol biosynthesis metabolite profile of HCV genotypes (GT) 2 and 3 patients treated with sofosbuvir+ribavirin.

METHODS

Serum samples [baseline, treatment week 12, 4weeks post-treatment] were analyzed for apolipoproteins B and E (apoB/E), total cholesterol, HDL, LDL, and 11 post-squalene sterol metabolites using a GC/MS platform.

RESULTS

We selected 127 patients (GT2 n=50, GT3 n=77), 50% cirrhotic patients, and 42% who experienced a virological relapse. At baseline, GT3 patients had lower level of serum lipids, apoB/E, 7-dehydrocholesterol, desmosterol, lathosterol, compared to GT2 (p<0.006). Baseline lathosterol was lower in relapsers with cirrhosis compared to cirrhotic patients with SVR (p=0.003). From baseline to treatment week 12, serum lipids, apoB/E, and key sterol pathway metabolites (7-dehydrocholesterol, desmosterol, lathosterol, lanosterol) increased in GT3. In contrast, in GT2 patients, apoB/E and dihydrolanosterol decreased with viral suppression (p<0.025). At follow-up week 4, cirrhotic SVR patients showed substantially greater increases in apoB and total sterols compared to cirrhotic relapsers regardless of HCV genotype. After adjustment for genotype and gender, baseline lathosterol was independently associated with virologic response (p=0.04).

CONCLUSION

HCV GT3 is associated with reduced circulation of lipids involved in the distal cholesterol biosynthesis pathway, resulting in relative hypocholesterolemia. HCV suppression during sofosbuvir+ribavirin restores distal sterol metabolites indicating viral interference with de novo lipogenesis or selective retention by hepatocytes.

Hepatitis C Virus NS4B Can Suppress STING Accumulation To Evade Innate Immune Responses

The cyclic dinucleotide 2',3'-cGAMP can bind the adaptor protein STING (stimulator of interferon [IFN] genes) to activate the production of type I IFNs and proinflammatory cytokines. We found that cGAMP added to the culture medium could suppress the replication of the hepatitis C virus (HCV) genotype 1b strain Con1 subgenomic replicon in human hepatoma cells. Knockdown of STING expression diminished the inhibitory effect on replicon replication, while overexpression of STING enhanced the inhibitory effects of cGAMP. The addition of cGAMP into 1b/Con1 replicon cells significantly increased the expression of type I IFNs and antiviral interferon-stimulated genes. Unexpectedly, replication of the genotype 2a JFH1 replicon and infectious JFH1 virus was less sensitive to the inhibitory effect of cGAMP than was that of 1b/Con1 replicon. Using chimeric replicons, 2a NS4B was identified to confer resistance to cGAMP. Transient expression of 2a NS4B resulted in a pronounced inhibitory effect on STING-mediated beta IFN (IFN-β) reporter activation compared to that of 1b NS4B. 2a NS4B was found to suppress STING accumulation in a dose-dependent manner. The predicted transmembrane domain of 2a NS4B was required to inhibit STING accumulation. These results demonstrate a novel genotype-specific inhibition of the STING-mediated host antiviral immune response.

IMPORTANCE

The cyclic dinucleotide cGAMP was found to potently inhibit the replication of HCV genotype 1b Con1 replicon but was less effective for the 2a/JFH1 replicon and infectious JFH1 virus. The predicted transmembrane domain in 2a NS4B was shown to be responsible for the decreased sensitivity to cGAMP. The N terminus of NS4B has been reported to suppress STING-mediated signaling by disrupting the interaction of STING and TBK1 and/or MAVS. We show that 2a/JFH1 NS4B has an additional mechanism to evade STING signaling through suppressing STING accumulation.

Viral genotype correlates with distinct liver gene transcription signatures in chronic hepatitis C virus infection

BACKGROUND

Chronic hepatitis C virus (HCV) infection of the liver with either genotype 1 or genotype 3 gives rise to distinct pathologies, and the two viral genotypes respond differently to antiviral therapy.

METHODS

To understand these clinical differences, we compared gene transcription profiles in liver biopsies from patients infected with either gt1 or gt3, and uninfected controls.

RESULTS

Gt1-infected biopsies displayed elevated levels of transcripts regulated by type I and type III interferons (IFN), including genes that predict response to IFN-α therapy. In contrast, genes controlled by IFN-γ were induced in gt3-infected biopsies. Moreover, IFN-γ levels were higher in gt3-infected biopsies. Analysis of hepatocyte-derived cell lines confirmed that the genes upregulated in gt3 infection were preferentially induced by IFN-γ. The transcriptional profile of gt3 infection was unaffected by IFNL4 polymorphisms, providing a rationale for the reduced predictive power of IFNL genotyping in gt3-infected patients.

CONCLUSIONS

The interactions between HCV genotypes 1 and 3 and hepatocytes are distinct. These unique interactions provide avenues to explore the biological mechanisms that drive viral genotype-specific differences in disease progression and treatment response. A greater understanding of the distinct host-pathogen interactions of the different HCV genotypes is required to facilitate optimal management of HCV infection.

Lipid dysregulation in hepatitis C virus, and impact of statin therapy upon clinical outcomes

The hepatitis C virus (HCV) is one of the most common causes of chronic liver disease and the leading indication for liver transplantation worldwide. Every aspect of the HCV life cycle is closely tied to human lipid metabolism. The virus circulates as a lipid-rich particle, utilizing lipoprotein cell receptors to gain entry into the hepatocyte. It has also been shown to upregulate lipid biosynthesis and impair lipid degradation, resulting in significant intracellular lipid accumulation and circulating hypocholesterolemia. Patients with chronic hepatitis C (CHC) are at increased risk of hepatic steatosis, fibrosis, and cardiovascular disease including accelerated atherosclerosis. HMG CoA Reductase inhibitors, or statins, have been shown to play an important role in the modulation of hepatic steatosis and fibrosis, and recent attention has focused upon their potential therapeutic role in CHC. This article reviews the hepatitis C viral life cycle as it impacts host lipoproteins and lipid metabolism. It then describes the pathogenesis of HCV-related hepatic steatosis, hypocholesterolemia and atherosclerosis, and finally describes the promising anti-viral and anti-fibrotic effects of statins, for the treatment of CHC.

Secondary hypertriglyceridemia in children and adolescents

Secondary dyslipidemia with predominant hypertriglyceridemia may occur as a consequence of both common and rare causes. After accounting for obesity and associated insulin resistance, clinicians should carefully consider other contributing factors and conditions. Genetic background and causative factors prevail during gestation, infancy, and childhood and continue in adults. Elevations in triglyceride (TG) are associated with transfer of TG to high-density lipoprotein (HDL) and low-density lipoprotein (LDL) resulting in lipolysis, HDL degradation, and formation of atherogenic LDL particles. Defining and treating the underlying cause is the first step toward restoring the lipids and lipoproteins to normal, especially in cases with severe hypertriglyceridemia, who are at risk for acute pancreatitis. Disorders involving the liver, kidney, endocrine, and immune systems and medications need to be considered. Rare diseases such as lipodystrophy and glycogen storage disease are particularly challenging, and there have been promising new developments. Treatment depends on the severity; prevention of acute pancreatitis being a priority in severe cases and lifestyle modification being a foundation for general management followed by targeting TG and predictors of coronary artery disease such as LDL cholesterol and non-HDL cholesterol, when they exceed cutpoints.

Elevated interferon-stimulated gene transcription in peripheral blood mononuclear cells occurs in patients infected with genotype 1 but not genotype 3 hepatitis C virus

Hepatitis C virus (HCV) can be classified into seven distinct genotypes that are associated with differing pathologies and respond differently to antiviral therapy. In the UK, genotype 1 and 3 are present in approximately equal proportions. Chronic infection with HCV genotype 3 is associated with increased liver steatosis and reduced peripheral total cholesterol levels, which potentially influences peripheral immune responses. To understand these differences, we investigated host gene transcription in peripheral blood mononuclear cells by microarray and quantitative PCR in patients with genotype 1 (n = 22) or genotype 3 infection (n = 22) and matched healthy controls (n = 15). Enrichment of genes involved in immune response and inflammatory pathways were present in patients infected with HCV genotype 1; however, no differences in genes involved in lipid or cholesterol metabolism were detected. This genotype-specific induction of genes is unrelated to IL28B genotype or previous treatment failure. Our data support the hypothesis that genotype 1 infection drives a skewed Type I interferon response and provides a foundation for future investigations into the host-pathogen interactions that underlie the genotype-specific clinical outcomes of chronic HCV infection.

Vitamin D deficiency in chronic liver disease

Vitamin D is an important secosteroid hormone with known effect on calcium homeostasis, but recently there is increasing recognition that vitamin D also is involved in cell proliferation and differentiation, has immunomodulatory and anti-inflammatory properties. Vitamin D deficiency has been frequently reported in many causes of chronic liver disease and has been associated with the development and evolution of non-alcoholic fatty liver disease (NAFLD) and chronic hepatitis C (CHC) virus infection. The role of vitamin D in the pathogenesis of NAFLD and CHC is not completely known, but it seems that the involvement of vitamin D in the activation and regulation of both innate and adaptive immune systems and its antiproliferative effect may explain its importance in these liver diseases. Published studies provide evidence for routine screening for hypovitaminosis D in patients with liver disease. Further prospectives studies demonstrating the impact of vitamin D replacement in NAFLD and CHC are required.

New insight of vitamin D in chronic liver diseases

BACKGROUND

Vitamin D is a fat-soluble sterol derivative that is predominantly synthesized in the liver and has multiple functions. The accumulative data showed that the clinical manifestations and prognosis of chronic liver diseases are associated with serum vitamin D levels.

DATA SOURCES

A PubMed and Google Scholar search using terms: "vitamin D", "25(OH)D", "liver disease", "viral hepatitis", "non-alcoholic fatty liver disease", "liver fibrosis", "cirrhosis", "hepatocellular carcinoma" and "autoimmune liver disease" was performed, and relevant articles published in English between January 2000 and March 2014 were reviewed. Full-text publications relevant to the field were selected and relevant articles from reference lists were also included.

RESULTS

The insufficiency or deficiency of vitamin D is common in various kinds of chronic liver diseases including viral hepatitis B and C. Serum 25-hydroxyvitamin D and vitamin D receptors are possibly interrelated with the incidence, treatment and prognosis of diseases. Though the evidence of vitamin D supplementation in viral hepatitis and associated liver diseases is still limited, there is great potential to apply this adjuvant therapy to improve the treatments.

CONCLUSIONS

Although the exact role and mechanisms of vitamin D have not been fully elucidated in chronic liver diseases, it is potentially beneficial in the treatment of chronic liver diseases. Further mechanistic studies are needed to validate its clinical application.

PCSK9 and its modulation

Proprotein convertase subtilisin/kexin type 9 (PCSK9), a newly-recognized protein, plays a key role in regulating cholesterol homeostasis. PCSK9 reduces hepatic low-density lipoprotein receptors (LDLRs) thereby increasing LDL-cholesterol (LDL-C). Recently, biologic and genetic research proposed several approaches to inhibit or reduce PCSK9 to improve lipid profile and cardiovascular performance in patients with dyslipidemia, particularly hypercholesterolemia. Of note, PCSK9 is a secreted protein under tight control by multiple modulators. Therefore, elucidating the factors that influence PCSK9 would enhance our understanding of PCSK9 and potentially day-to-day management of these patients at high cardiovascular risk. This review will focus on genetic variants, physiologic processes, pharmacologic agents and pathologic conditions related to PCSK9 in order to assess current and future therapeutic strategies targeting this molecule.

Predictive factors for sustained virological response after treatment with pegylated interferon α-2a and ribavirin in patients infected with HCV genotypes 2 and 3

Background

Previous trials have often defined genotype 2 and 3 patients as an “easy to treat” group and guidelines recommend similar management.

Aims

The present study looks for differences between the two genotypes and analyzes predictive factors for SVR.

Methods

Prospective, community-based cohort study involving 421 physicians throughout Germany. The analysis includes 2,347 patients with untreated chronic HCV genotype 2 (n = 391) and 3 (n = 1,956) infection treated with PEG-IFN α-2a plus ribavirin between August 2007 and July 2012.

Results

When compared with genotype 2 patients, those with genotype 3 were younger, had a shorter duration of infection, lower values of total cholesterol, LDL cholesterol and BMI, a higher frequency of drug use as infection mode and male gender (p<0.0001, respectively), and a higher APRI score (p<0.005). SVR was higher in genotype 2 when compared with genotype 3 (64.7% vs. 56.9%, p = 0.004). By multivariate analysis of genotype 2 patients, low baseline γ -GT and RVR predicted SVR. In genotype 3 age ≤45 years, cholesterol>130 mg/dl, a low APRI score, and a γ-GT ≥3-times ULN, RVR, and RBV starting dose were associated with SVR by multivariate analysis.

Conclusions

The present study corroborates that liver fibrosis is more pronounced in genotype 3 vs. 2. SVR is higher in genotype 2 versus genotype 3 partly because of follow-up problems in genotype 3 patients, in particular in those infected by drug use. Thus, subgroups of genotype 3 patients have adherence problems and need special attention also because they often have significant liver fibrosis.

Trial Registration

Verband Forschender Arzneimittelhersteller e.V., Berlin, Germany ML21645 ClinicalTrials.gov NCT02106156

Hepatitis C virus infection mediates cholesteryl ester synthesis to facilitate infectious particle production

Cholesterol is a critical component of the hepatitis C virus (HCV) life cycle, as demonstrated by its accumulation within infected hepatocytes and lipoviral particles. To cope with excess cholesterol, hepatic enzymes ACAT1 and ACAT2 produce cholesteryl esters (CEs), which are destined for storage in lipid droplets or for secretion as apolipoproteins. Here we demonstrate in vitro that cholesterol accumulation following HCV infection induces upregulation of the ACAT genes and increases CE synthesis. Analysis of human liver biopsy tissue showed increased ACAT2 mRNA expression in liver infected with HCV genotype 3, compared with genotype 1. Inhibiting cholesterol esterification using the potent ACAT inhibitor TMP-153 significantly reduced production of infectious virus, but did not inhibit virus RNA replication. Density gradient analysis showed that TMP-153 treatment caused a significant increase in lipoviral particle density, suggesting reduced lipidation. These data suggest that cholesterol accumulation following HCV infection stimulates the production of CE, a major component of lipoviral particles. Inhibition of CE synthesis reduces HCV particle density and infectivity, suggesting that CEs are required for optimal infection of hepatocytes.

[Impact of antiviral therapy on the natural history of hepatitis C virus]

Chronic hepatitis C virus infection affects around 150 million persons, and 350,000 persons worldwide die of this disease each year. Although the data on its natural history are incomplete, after the acute infection, most patients develop chronic forms of hepatitis C with variable stages of fibrosis. In these patients, continual inflammatory activity can cause significant fibrosis, cirrhosis, decompensation of the liver disease, or hepatocarcinoma. In the next few years, it is expected that hepatitis C virus infection and its complications will significantly increase, as will the incidence of hepatocarcinoma in Spain. This review presents the data on the natural history of hepatitis C virus infection and discusses the potential impact of antiviral therapy on the distinct stages of the disease.

Pathogenesis and significance of hepatitis C virus steatosis: An update on survival strategy of a successful pathogen

Hepatitis C virus (HCV) is a successful pathogen on the grounds that it exploits its host’s metabolism to build up viral particles; moreover it favours its own survival by inducing chronic disease and the development of specific anatomic changes in the infected organ. Steatosis, therefore, is associated with HCV infection by necessity rather than by chance alone. Approximately 6% of HCV patients have steatohepatitis. Interestingly, HCV steatosis occurs in the setting of multiple metabolic abnormalities (hyperuricemia, reversible hypocholesterolemia, insulin resistance, arterial hypertension and expansion of visceral adipose tissue) collectively referred to as “hepatitis C-associated dysmetabolic syndrome” (HCADS). General, nonalcoholic fatty liver disease (NAFLD)-like, mechanisms of steatogenesis (including increased availability of lipogenic substrates and de novo lipogenesis; decreased oxidation of fatty substrates and export of fatty substrates) are shared by all HCV genotypes. However, genotype 3 seemingly amplifies such steatogenic molecular mechanisms reported to occur in NAFLD via more profound changes in microsomal triglyceride transfer protein; peroxisome proliferator-activated receptor alpha; sterol regulatory element-binding proteins and phosphatase and tensin homologue. HCV steatosis has a remarkable clinical impact in as much as it is an acknowledged risk factor for accelerated fibrogenesis; for impaired treatment response to interferon and ribavirin; and development of hepatocellular carcinoma. Recent data, moreover, suggest that HCV-steatosis contributes to premature atherogenesis via both direct and indirect mechanisms. In conclusion, HCV steatosis fulfills all expected requirements necessary to perpetuate the HCV life cycle. A better understanding of the physiology of HCADS will likely result in a more successful handling of disease with improved antiviral success rates.