HCV and the hepatic lipid pathway as a potential treatment target

HCV NS3/4A protease relocalizes CCTα to viral replication sites, enhancing phosphatidylcholine synthesis and viral replication

Positive-sense single-stranded RNA [(+)RNA] viruses constitute more than one-third of all virus genera, including numerous pathogens of clinical significance. All (+)RNA viruses reorganize cellular membranes from organelles to establish replication compartments (RCs). These RCs are thought to form a platform for membrane-associated replicases, in addition to protecting the viral RNAs from cytosolic innate immune signaling and RNA-degradation machinery. Previous work demonstrated that three families of (+)RNA viruses, namely Bromoviridae, Picornaviridae, and Flaviviridae, commonly induce the accumulation of phosphatidylcholine (PC) at their RCs. This phenomenon suggests a potential avenue for a broad-spectrum antiviral strategy targeting PC metabolism. Our study elucidates three key observations: i) hepatitis C virus (HCV) infection prompts the relocalization of CCTα, the rate-limiting enzyme in PC synthesis, to the RCs; ii) the enhancement of PC synthesis is contingent upon the protease activity of the NS3/4A protein; and iii) utilizing click chemistry, we demonstrate that HCV infection stimulates de novo PC synthesis at the viral replication site through the Kennedy pathway. These findings provide significant insights into the manipulation of lipid metabolism by HCV during RC formation, a mechanism likely conserved across various (+)RNA virus families.

Golgi protein 73: the driver of inflammation in the immune and tumor microenvironment

Golgi Protein 73 (GP73) is a Golgi-resident protein that is highly expressed in primary tumor tissues. Initially identified as an oncoprotein, GP73 has been shown to promote tumor development, particularly by mediating the transport of proteins related to epithelial-mesenchymal transition (EMT), thus facilitating tumor cell EMT. Though our previous review has summarized the functional roles of GP73 in intracellular signal transduction and its various mechanisms in promoting EMT, recent studies have revealed that GP73 plays a crucial role in regulating the tumor and immune microenvironment. GP73 can modulate intracellular signaling pathways to influence cytokine and chemokine networks, resulting in inflammation caused by viral and bacterial infection or immune diseases, and leading tumor microenvironment deteriorated. Additionally, extracellular GP73 can also regulate signaling pathways of target cells by binding to their cell-surface receptors or entering the acceptor cells, thereby facilitating inflammation or promoting tumor development. In this review, we aim to summarize the findings, providing insights for future investigations on GP73 and its potential as a therapeutic target in ameliorating chronic inflammation in the immune and tumor microenvironment.

Unveiling the Multifaceted Role of CIDEB: From Apoptosis to Lipid Metabolism and Liver Health

Cell-death-inducing DNA fragmentation factor-alpha (DFFA)-like effector b (CIDEB) was first identified as an apoptosis-inducing protein. Further research revealed a pivotal role in lipid metabolism, regulating very-low-density lipoprotein (VLDL), lipid droplets (LD), sterol response element-binding protein (SREBP), and chylomicrons. Recent studies have uncovered that rare germline variants in CIDEB protect against liver diseases, including MAFLD, cirrhosis, and viral hepatitis. Furthermore, CIDEB influences steps of the hepatitis C virus (HCV) replication cycle. This review summarizes the current knowledge about CIDEB’s roles in apoptosis, lipid metabolism, and viral hepatitis, and highlights its critical role in liver diseases.

Role of triglycerides as a predictor of autoimmune hepatitis with cirrhosis

Background

Metabolism-related indicators have been suggested as possible prognostic indicators of liver disease in recent relevant studies, but their value in predicting autoimmune hepatitis (AIH) cirrhosis is unclear. This study evaluated the role of lipid levels in determining the prognosis of AIH-related cirrhosis.

Methods

We retrospectively included 345 patients with AIH who were initially diagnosed at Beijing Ditan Hospital from 2010-2019, and ultimately screened 196 patients who met the criteria. A logistic regression analysis was performed to screen factors associated with cirrhosis. Kaplan–Meier (KM) curves were constructed to analyze the effects of different triglyceride (TG) levels on the survival of patients with cirrhosis. A restricted cubic spline fitted Cox regression model was used to analyze the nonlinear relationship between serum TG levels and patient prognosis.

Results

Patients with AIH cirrhosis have lower TG levels than those without cirrhosis. Lower serum TG levels correlated with the severity of cirrhosis. The survival analysis showed that TG levels were associated with the overall survival of patients with AIH, as a lower 5-year survival rate (log-rank P<0.05) was observed for patients in the TG≤0.95 mmol/L group (hazard ratio (HR)=3.79, 95% CI: 1.528-9.423). In addition, lower TG levels were associated with a higher incidence of death in patients with AIH cirrhosis. The risk of death gradually increased for the interval of TG levels of 0.5-0.8 mmol/L (P for nonlinearity<0.001), and the hazard ratio per standard deviation increase in the TG level was 0.97 (95% CI: 0.94-0.99). The plot showed a U-shaped relationship between TG levels and the survival of patients with decompensated cirrhosis. The risk ratio progressively decreased with lower TG levels (P for nonlinearity=0.002). Below 0.6 mmol/L, the probability of TG risk per standard deviation prediction was 1.49 (95% CI: 1.00-2.24).

Conclusion

Serum TG levels are closely related to the disease severity and overall survival of patients with AIH cirrhosis and may be used as a new indicator of advanced liver disease and long-term prognosis.

A Simple and Effective Method to Concentrate Hepatitis C Virus: Aqueous Two-Phase System Allows Highly Efficient Enrichment of Enveloped Viruses

To investigate the proliferation cycle of a virus, virus-host interaction, and pathogenesis of a virus, virion particles must be concentrated from the media of virus cell culture or the sera of virus-infected patients. Ultracentrifugation of the culture media is a standard method for concentrating virion particles. However, this method is time-consuming and requires special equipment (ultracentrifuge). Moreover, a large number of infectious viruses are lost during enrichment. We developed a new method of hepatitis C virus (HCV) concentration to overcome the issues associated with traditional methods of virus concentration. We used an aqueous two-phase system (ATPS) to concentrate the virus. HCV, which causes various liver diseases, such as liver fibrosis, cirrhosis, and hepatocellular carcinoma, was used as a model virus to test the efficacy and reliability of the ATPS. The efficiency of HCV concentration by the ATPS was approximately three times higher than that by ultracentrifugation. Moreover, the infectivity of the concentrated HCV, which is a labile virus, remained the same after concentration of the virus by the ATPS. Considering the simplicity and effectiveness of the ATPS, it is the method of choice for concentrating viruses.

MicroRNA-206 inhibits HCV proliferation through depressing ACC1 lipid synthesis signalling pathway

MicroRNAs are considered to play important roles in cell biological and pathological progress. microRNA-206 (miR-206) was reported to participate in lipogenesis, and lipid droplets were necessary for the life cycle of HCV proliferation. Whether miR-206 was associated with HCV proliferation and the potential mechanism are not clear. In this study, we firstly identified that miR-206 could inhibit HCV proliferation at the RNA and protein level. Bioinformatical prediction of target genes binding to miR-206 was performed to investigate whether inhibiting function was due to a lipogenesis pathway. Then, the acetyl-CoA carboxylase 1 (ACC1) gene was selected as target gene of miR-206. The dual-luciferase reporter assay results showed that luciferase significantly decreased in cells transfected with 3'-UTR of the ACC1 gene and miR-206. The RNA and protein levels of the ACC1 gene and its pathway genes were significantly lower in cells transfected with miR-206 than in controls. Furthermore, the lipid droplet numbers also significantly decreased in cells transfected with miR-206. In conclusion, miR-206 could inhibit HCV proliferation through depressing ACC1 lipogenesis pathway and decreasing the lipid droplet numbers. miR-206 might be used as anti-HCV biochemical drug in the future.

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.

Association of lipid profile with decompensation, liver dysfunction, and mortality in patients with liver cirrhosis

BACKGROUND AND AIMS

Lipid metabolism is often disrupted in liver cirrhosis. The present study aimed to evaluate the impact of lipid profile on decompensation events, severity of liver dysfunction, and death in patients with liver cirrhosis.

METHODS

In a cross-sectional study, 778 patients with lipid profile data were enrolled, and then were divided into 240 and 538 patients with and without liver cirrhosis, respectively. In a cohort study, 314 cirrhotic patients with lipid profile data, who were prospectively followed, were enrolled. Lipid profile included total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-c), low-density lipoprotein-cholesterol (LDL-c), triglycerides (TG), and lipoprotein(a).

RESULTS

In the cross-sectional study, cirrhotic patients with decompensation events had significantly lower levels of TC and lipoprotein(a) than those without; and cirrhotic patients with Child-Pugh class B and C had significantly lower levels of TC, HDL-c, LDL-c, and lipoprotein(a) than those with Child-Pugh class A. In the cohort study, there was an inverse association of survival with TC, HDL-c, and lipoprotein(a) levels; after adjusting for MELD score, TC (Hazard Ratio [HR] = 1.703, P = 0.034) and HDL-c (HR = 2.036, P = 0.005), but not lipoprotein(a) (HR = 1.377, P = 0.191), remained a significant predictor of death; when TC, HDL-c, lipoprotein(a), and MELD score were included in the multivariate Cox regression analysis, HDL-c (HR = 1.844, P = 0.024) was the only independent predictor of death.

CONCLUSIONS

Decreased levels in specific components of lipid profile indicate more decompensation events, worse liver function, and reduced survival in liver cirrhosis. MELD score combined with HDL-c should be promising for the assessment of outcomes of cirrhotic patients.

Dysregulation in Plasma ω3 Fatty Acids Concentration and Serum Zinc in Heavy Alcohol-Drinking HCV Patients

Alcohol use disorder (AUD) patients comorbid with hepatitis C virus (HCV) infection (HCV + AUD) could have progressively severe clinical sequels of liver injury and inflammation. Serum zinc and several polyunsaturated fatty acids (PUFAs) get dysregulated in AUD as well as HCV. However, the extent of dysregulation of PUFAs and zinc deficiency and their interaction in HCV + AUD as a comorbid pathology has not been studied. We examined the role of dysregulation of FAs and low zinc in HCV + AUD patients. 138 male and female participants aged 21-67 years were grouped as HCV-only (Gr. 1; n = 13), HCV + AUD (Gr. 2; n = 25), AUD without liver injury (Gr. 3; n = 37), AUD with liver injury (Gr. 4; n = 51), and healthy volunteers (Gr. 5 or HV; n = 12). Drinking history, individual demographic measures, fasting fatty acids, liver function, and zinc were measured and analyzed. HCV + AUD patients showed the highest ALT level compared to the rest of the groups. Serum zinc concentrations were the lowest, and the proinflammatory shift was the highest (characterized by ω6 : ω3 ratio) in the HCV + AUD patients. Total ω3, eicosapentaenoic acid (EPA), and docosapentaenoic acid (DPA5,3) were the lowest in HCV + AUD patients. Total ω3, α-linoleic acid (α-LA) along with covariable number of drinking days past 90 days (NDD90), eicosapentaenoic acid (EPA), and docosapentaenoic acid (DPA5,3) independently showed significant association with low zinc in the HCV + AUD patients. Heavy drinking pattern showed that NDD90 has a significant mediating role in the representation of the relationship between candidate ω3 PUFAs and zinc uniquely in the HCV + AUD patients. Low serum zinc showed a distinctively stronger association with total and candidate ω3s in the HCV + AUD patients compared to the patients with HCV or AUD alone, supporting dual mechanism involved in the exacerbation of the proinflammatory response in this comorbid cohort. This trial is registered with NCT#00001673.

The Impact of Mevastatin on HCV Replication and Autophagy of Non-Transformed HCV Replicon Hepatocytes Is Influenced by the Extracellular Lipid Uptake

Statins efficiently inhibit cholesterol synthesis by blocking 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase in the mevalonate pathway. However, the effect of statins on intracellular cholesterol is partially counterbalanced by a consequent increased uptake of extracellular lipid sources. Hepatitis C virus (HCV) infection induces intracellular accumulation of cholesterol by promoting both new synthesis and uptake of circulating lipoproteins, which is required for HCV replication and release. Hepatocytes respond to the increase in intracellular cholesterol levels by inducing lipophagy, a selective type of autophagy mediating the degradation of lipid deposits within lysosomes. In a cellular system of HCV replication based on HuH7 hepatoma cells, statin treatment was shown to be sufficient to decrease intracellular cholesterol, which is accompanied by reduced HCV replication and decreased lipophagy, and has no apparent impact on endocytosis-mediated cholesterol uptake. To understand whether these results were influenced by an altered response of cholesterol influx in hepatoma cells, we analyzed the effect of statins in non-transformed murine hepatocytes (MMHD3) harboring subgenomic HCV replicons. Notably, we found that total amount of cholesterol is increased in MMHD3 cells upon mevastatin treatment, which is associated with increased HCV replication and lipophagy. Conversely, mevastatin is able to reduce cholesterol amounts only when cells are grown in the presence of delipidated serum to prevent extracellular lipid uptake. Under this condition, HCV replication is reduced and autophagy flux is severely impaired. Altogether, these results indicate that both de novo synthesis and extracellular uptake have to be targeted in non-transformed hepatocytes in order to decrease intracellular cholesterol levels and consequently limit HCV replication.

Rapid Changes in Serum Lipid Profiles during Combination Therapy with Daclatasvir and Asunaprevir in Patients Infected with Hepatitis C Virus Genotype 1b

Background/Aims

Changes in lipid profiles in patients infected with hepatitis C virus (HCV) during direct-acting antiviral therapy have been reported in recent years. However, the clinical aspects of disturbed lipid metabolism in chronic HCV infection have not been fully elucidated.

Methods

Dynamic changes in serum total, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol and apolipoprotein levels in patients infected with HCV genotype 1b were examined during combination therapy with daclatasvir (DCV) and asunaprevir (ASV).

Results

Total, LDL−, and HDL-cholesterol levels increased rapidly and persistently after week 4. Apolipoprotein (apo) A-I, apo B, apo C-II, and apo C-III levels were significantly higher at week 4 than at week 0. In contrast, apo A-II and apo E levels were significantly lower. The differences in LDL− and HDL-cholesterol levels were positively correlated with those of apo B and apo A-I, respectively. Interestingly, in patients with non-sustained virological response, these cholesterol levels decreased rapidly after viral breakthrough or viral relapse. Furthermore, similar changes were observed for apo A-I, apo B and apo C-III levels.

Conclusions

Clearance of HCV using combination therapy with DCV and ASV results in rapid changes in serum lipid profiles, suggesting an influence of HCV infection on disturbed lipid metabolism.

Abnormalities of Lipoprotein Levels in Liver Cirrhosis: Clinical Relevance

Progressive lipoprotein impairment occurs in liver cirrhosis and is associated with increased morbidity and mortality. The present review aims to summarize the current evidence regarding the prognostic value of lipoprotein abnormalities in liver cirrhosis and to address the need of a better prognostic stratification of patients, including lipoprotein profile assessment. Low levels of lipoproteins are usual in cirrhosis. Much evidence supports the prognostic role of hypolipidemia in cirrhotic patients. In particular, hypocholesterolemia represents an independent predictor of survival in cirrhosis. In cirrhotic patients, lipoprotein impairment is associated with several complications: infections, malnutrition, adrenal function, and spur cell anemia. Alterations of liver function are associated with modifications of circulating lipids. Decreased levels of lipoproteins significantly impact the survival of cirrhotic patients and play an important role in the pathogenesis of some cirrhosis-related complications.

Lysophosphatidylcholine acyltransferase 1 is downregulated by hepatitis C virus: impact on production of lipo-viro-particles

OBJECTIVE

HCV is intimately linked with the liver lipid metabolism, devoted to the efflux of triacylglycerols stored in lipid droplets (LDs) in the form of triacylglycerol-rich very-low-density lipoproteins (VLDLs): (i) the most infectious HCV particles are those of lowest density due to association with triacylglycerol-rich lipoproteins and (ii) HCV-infected patients frequently develop hepatic steatosis (increased triacylglycerol storage). The recent identification of lysophosphatidylcholine acyltransferase 1 (LPCAT1) as an LD phospholipid-remodelling enzyme prompted us to investigate its role in liver lipid metabolism and HCV infectious cycle.

DESIGN

Huh-7.5.1 cells and primary human hepatocytes (PHHs) were infected with JFH1-HCV. LPCAT1 depletion was achieved by RNA interference. Cells were monitored for LPCAT1 expression, lipid metabolism and HCV production and infectivity. The density of viral particles was assessed by isopycnic ultracentrifugation.

RESULTS

Upon HCV infection, both Huh-7.5.1 cells and PHH had decreased levels of LPCAT1 transcript and protein, consistent with transcriptional downregulation. LPCAT1 depletion in either naive or infected Huh-7.5.1 cells resulted in altered lipid metabolism characterised by LD remodelling, increased triacylglycerol storage and increased secretion of VLDL. In infected Huh-7.5.1 cells or PHH, LPCAT1 depletion increased production of the viral particles of lowest density and highest infectivity.

CONCLUSIONS

We have identified LPCAT1 as a modulator of liver lipid metabolism downregulated by HCV, which appears as a viral strategy to increase the triacylglycerol content and hence infectivity of viral particles. Targeting this metabolic pathway may represent an attractive therapeutic approach to reduce both the viral titre and hepatic steatosis.

Exploration of potential mechanisms of hepatitis C virus resistance in exposed uninfected intravenous drug users

A rare outcome following exposure to hepatitis C virus (HCV) is a lack of observable infection as clinically measured by HCV RNA- or HCV-recognizing antibodies. The population who exhibit this trait is termed exposed uninfected (EU). Increasing evidence has refined characterization of these individuals, distinct from those who become infected but spontaneously clear HCV. Study of the EU population is highly pertinent for the discovery of antiviral mechanisms of resistance that can reveal antiviral therapeutic strategies. This review provides an overview of similarities and differences of the EU population relative to spontaneous resolvers and the majority whom develop chronic HCV infection, and focusses on possible mechanisms of resistance including innate and adaptive immunity, genetics and lipid interactions.

Impact of Apo E gene polymorphism on HCV therapy related outcome in a cohort of HCV Egyptian patients

The functional apolipoprotein E (Apo E) gene polymorphism could be used as a determinant of outcome of HCV infection. This study aimed to demonstrate the impact of Apo E genotype on the response to HCV combined therapy.

MATERIAL AND METHODS

The study has been implemented on 125 individuals with persistent HCV infection and 120 cases with sustained virologic response (SVR). All participants were genotyped for ApoE gene polymorphism by a real-time quantitative PCR (qPCR).

RESULTS

Statistically significant differences were demonstrated regarding the Apo E genotypes between the two groups (P-value < .001) where the frequency of E3E3 was significantly higher among the chronic HCV-patients while E3E4 and E4E4 genotypes frequencies were higher among the SVR-subjects group and E3E3 genotype was associated with increased risk of chronicity (OR 4.7; 95% CI 1.9-12.1, P-value < .001). Moreover, There were statically significant differences regarding E3 and E4 alleles frequencies, where E3 allele display a higher frequency among the chronic HCV-patient group while the SVR-subjects group showed higher frequency of E4 allele and the carriers of E3 allele have 1.4 times more risk to develop chronicity than those with E4 allele (OR 1.4; 95% CI 1.0-2.0, P-value < .05). Meanwhile the protective E2 allele was absent in all infected participants.

CONCLUSION

This study supports the hypothesis of the protective impact of Apo E4 allele that favors viral clearance of HCV infection and its recovery after combined therapy, while the Apo E3 allele is considered as a particular risk factor for the chronicity in HCV patients and resistance to therapy. Whereas the Apo E2 allele confers a resistance to HCV infection at a time of exposure.

The effect of the TM6SF2 E167K variant on liver steatosis and fibrosis in patients with chronic hepatitis C: a meta-analysis

The impact of Transmembrane 6 superfamily member 2 (TM6SF2) E167K variant, which causes hepatocellular fat retention by altering lipoprotein secretion, on liver damage and metabolic traits in chronic hepatitis C patients is still debated. We performed a systematic review and meta-analysis to clarify this relationship. Four studies with a total of 4325 patients were included. The risk of histologically-determined advanced steatosis, fibrosis, and cirrhosis (but not of severe inflammation) were increased in carriers of the TM6SF2 variant (P < 0.05). Unlike the inconsistent association with steatosis severity, due to the confounding effect of infection by the genotype-3 hepatitis C virus, the TM6SF2 variant was robustly associated with advanced fibrosis (OR = 1.07; 95% confidence interval [CI] = 1.01–1.14) and in particular with cirrhosis (OR = 2.05; 95% CI = 1.39–3.02). Regarding metabolic features, individuals positive for the TM6SF2 variant exhibited 5.8–12.0% lower levels of circulating triglycerides and non-HDL cholesterol (P < 0.05). Carriers of the variant were leaner, but there was high heterogeneity across studies (I² = 97.2%). No significant association was observed between the TM6SF2 variant and insulin resistance or hepatitis C viral load (both P > 0.05). In conclusion, the TM6SF2 E167K variant promotes the development of steatosis, fibrosis and cirrhosis in patients with chronic hepatitis C. Conversely, this variant reduces circulating atherogenic lipid fractions.

The Plasma and Serum Metabotyping of Hepatocellular Carcinoma in a Nigerian and Egyptian Cohort using Proton Nuclear Magnetic Resonance Spectroscopy

BACKGROUND/AIMS

Previous studies have observed disturbances in the ¹H nuclear magnetic resonance (NMR) blood spectral profiles in malignancy. No study has metabotyped serum or plasma of hepatocellular carcinoma (HCC) patients from two diverse populations. We aimed to delineate the HCC patient metabotype from Nigeria (mostly hepatitis B virus infected) and Egypt (mostly hepatitis C virus infected) to explore lipid and energy metabolite alterations that may be independent of disease aetiology, diet and environment.

METHODS

Patients with HCC (53) and cirrhosis (26) and healthy volunteers (19) were recruited from Nigeria and Egypt. Participants provided serum or plasma samples, which were analysed using 600 MHz ¹H NMR spectroscopy with nuclear Overhauser enhancement spectroscopy pulse sequences. Median group spectra comparison and multivariate analysis were performed to identify regions of difference.

RESULTS

Significant differences between HCC patients and healthy volunteers were detected in levels of low density lipoprotein (P = 0.002), very low density lipoprotein (P < 0.001) and lactate (P = 0.03). N-acetylglycoproteins levels in HCC patients were significantly different from both healthy controls and cirrhosis patients (P < 0.001 and 0.001).

CONCLUSION

Metabotype differences were present, pointing to disturbed lipid metabolism and a switch from glycolysis to alternative energy metabolites with malignancy, which supports the Warburg hypothesis of tumour metabolism.

Hepatitis C virus G1b infection decreases the number of small low-density lipoprotein particles

AIM

To investigate how hepatitis C virus (HCV) G1b infection influences the particle number of lipoproteins.

METHODS

The numbers of lipoprotein particles in fasting sera from 173 Japanese subjects, 82 with active HCV G1b infection (active HCV group) and 91 with cleared HCV infection (SVR group), were examined. Serum lipoprotein was fractionated by high-performance liquid chromatography into twenty fractions. The cholesterol and triglyceride concentrations in each fraction were measured using LipoSEARCH. The number of lipoprotein particles in each fraction was calculated using a newly developed algorithm, and the relationship between chronic HCV G1b infection and the lipoprotein particle number was determined by multiple linear regression analysis.

RESULTS

The median number of low-density lipoprotein (LDL) particles was significantly lower in the active HCV group [1182 nmol/L, interquartile range (IQR): 444 nmol/L] than in the SVR group (1363 nmol/L, IQR: 472 nmol/L, P < 0.001), as was that of high-density lipoprotein (HDL) particles (14168 nmol/L vs 15054 nmol/L, IQR: 4114 nmol/L vs 3385 nmol/L, P = 0.042). The number of very low-density lipoprotein (VLDL) particles was similar between the two groups. Among the four LDL sub-fractions, the number of large LDL particles was similar between the two groups. However, the numbers of medium (median: 533.0 nmol/L, IQR: 214.7 nmol/L vs median: 633.5 nmol/L, IQR: 229.6 nmol/L, P < 0.001), small (median: 190.9 nmol/L, IQR: 152.4 nmol/L vs median: 263.2 nmol/L, IQR: 159.9 nmol/L; P < 0.001), and very small LDL particles (median: 103.5 nmol/L, IQR: 66.8 nmol/L vs median: 139.3 nmol/L, IQR: 67.3 nmol/L, P < 0.001) were significantly lower in the active HCV group than in the SVR group, respectively. Multiple linear regression analysis indicated an association between HCV G1b infection and the decreased numbers of medium, small, and very small LDL particles. However, active HCV infection did not affect the number of large LDL particles or any sub-fractions of VLDL and HDL particles.

CONCLUSION

HCV G1b infection decreases the numbers of medium, small, and very small LDL particles.

Roles of Lipoproteins and Apolipoproteins in Particle Formation of Hepatitis C Virus

More than 160 million people worldwide are infected with hepatitis C virus (HCV), and cirrhosis and hepatocellular carcinoma induced by HCV infection are life-threatening diseases. HCV takes advantage of many aspects of lipid metabolism for an efficient propagation in hepatocytes. Due to the morphological and physiological similarities of HCV particles to lipoproteins, lipid-associated HCV particles are named lipoviroparticles. Recent analyses have revealed that exchangeable apolipoproteins directly interact with the viral membrane to generate infectious HCV particles. In this review, we summarize the roles of lipid metabolism in the life cycle of HCV.

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.

Nonalcoholic fatty liver disease and hepatic cirrhosis: Comparison with viral hepatitis-associated steatosis

Nonalcoholic fatty liver disease (NAFLD) including nonalcoholic steatohepatitis (NASH) is globally increasing and has become a world-wide health problem. Chronic infection with hepatitis B virus or hepatitis C virus (HCV) is associated with hepatic steatosis. Viral hepatitis-associated hepatic steatosis is often caused by metabolic syndrome including obesity, type 2 diabetes mellitus and/or dyslipidemia. It has been reported that HCV genotype 3 exerts direct metabolic effects that lead to hepatic steatosis. In this review, the differences between NAFLD/NASH and viral hepatitis-associated steatosis are discussed.

Ledipasvir/sofosbuvir treatment of hepatitis C virus is associated with reduction in serum apolipoprotein levels

The interaction of lipoproteins with hepatitis C virus (HCV) has pathogenic and therapeutic implications. Our aim was to evaluate changes in the apolipoprotein profile of patients with chronic hepatitis C during and after successful cure with ledipasvir and sofosbuvir (LDV/SOF) with and without ribavirin (RBV). One hundred HCV genotype 1 patients who had achieved SVR-12 after treatment with 12 weeks of LDV/SOF ± RBV were selected from the ION-1 clinical trial. Frozen serum samples from baseline, end of treatment and week 4 of follow-up were used to assay apolipoproteins (apoAI, apoAII, apoB, apoCII, apoCIII, apoE) using the Multiplex platform to assess for changes in the apolipoprotein levels. At the end of treatment compared to baseline, a significant reduction in apoAII levels (-14.97 ± 63.44 μg/mL, P = 0.0067) and apoE levels (-4.38 ± 12.19 μg/mL, P < 0.001) was noted. These declines from baseline in apoAII (-16.59 ±66.15 μg/mL, P = 0.0075) and apoE (-2.66 ± 12.64 μg/mL, P = 0.015) persisted at 4 weeks of post-treatment follow-up. In multivariate analysis, treatment with LDV/SOF + RBV was independently associated with reduction in apoE (beta = 5.31 μg/mL, P = 0.002) (compared to RBV-free LDV/SOF) (P < 0.05). In contrast, apoCII levels overall increased from baseline to end of treatment (+2.74 ±11.76 μg/mL, P = 0.03) and persisted at 4 weeks of follow-up (+4.46 ± 12.81 μg/mL from baseline, P = 0.0005). Subgroup analysis revealed an increase in apoCII during treatment only in patients receiving LDV/SOF without RBV (+5.52 ± 11.92 μg/mL, P = 0.0007) but not in patients receiving LDV/SOF + RBV (P = 0.638). Treatment with LDV/SOF ± RBV is associated with a persistent reduction in the apolipoprotein AII and E after achieving cure. These data suggest that treatment with LDV/SOF ± RBV may be associated with alterations in serum apolipoproteins which could potentially impact viral eradication.

Increased circulating adiponectin in males with chronic HCV hepatitis

BACKGROUND

Increased levels of adiponectin, a major adipokine with insulin sensitizing properties showing a strong sexual dimorphism, have been reported in individuals with chronic HCV infection (CHC), but data are limited by small samples and lack of control for the genetic background and hepatic fibrosis. The aim of this study was to compare adiponectin levels between CHC patients and accurately matched controls.

METHODS

We considered 184 CHC patients, matched (1:1) for age, gender, body mass index, and Adiponectin genotype (ADIPOQ) with healthy individuals. To control for the severity of liver disease, a second control group consisting of 95 patients with histological nonalcoholic fatty liver disease (NAFLD) further matched (1:1) for severe fibrosis was exploited. ADIPOQ genotype was evaluated by Taqman assays, serum adiponectin measured by ELISA.

RESULTS

Serum adiponectin was higher in CHC patients than in healthy individuals (9.0±5.0 μg/ml vs. 7.3±4.0 μg/ml; p=0.001; adjusted estimate +1.8, 1.7-2.9; p=0.001), and than in NAFLD patients (8.3±4.5 μg/ml vs. 6.0±4.2 μg/ml; p<0.001; adjusted estimate +0.8, 0.2-1.4, p=0.006). After stratification for sex, serum adiponectin was higher in males with CHC than in healthy individuals and NAFLD patients (p<0.005 for both), whereas the difference was not significant in females.

CONCLUSIONS

CHC is associated with increased serum adiponectin independently of age, body mass, diabetes, ADIPOQ genotype, and of severe liver fibrosis, particularly in men.

Chronic hepatitis C virus infection and lipoprotein metabolism

Hepatitis C virus (HCV) is a hepatotrophic virus and a major cause of chronic liver disease, including hepatocellular carcinoma, worldwide. The life cycle of HCV is closely associated with the metabolism of lipids and lipoproteins. The main function of lipoproteins is transporting lipids throughout the body. Triglycerides, free cholesterol, cholesteryl esters, and phospholipids are the major components of the transported lipids. The pathway of HCV assembly and secretion is closely linked to lipoprotein production and secretion, and the infectivity of HCV particles largely depends on the interaction of lipoproteins. Moreover, HCV entry into hepatocytes is strongly influenced by lipoproteins. The key lipoprotein molecules mediating these interactions are apolipoproteins. Apolipoproteins are amphipathic proteins on the surface of a lipoprotein particle, which help stabilize lipoprotein structure. They perform a key role in lipoprotein metabolism by serving as receptor ligands, enzyme co-factors, and lipid transport carriers. Understanding the association between the life cycle of HCV and lipoprotein metabolism is important because each step of the life cycle of HCV that is associated with lipoprotein metabolism is a potential target for anti-HCV therapy. In this article, we first concisely review the nature of lipoprotein and its metabolism to better understand the complicated interaction of HCV with lipoprotein. Then, we review the outline of the processes of HCV assembly, secretion, and entry into hepatocytes, focusing on the association with lipoproteins. Finally, we discuss the clinical aspects of disturbed lipid/lipoprotein metabolism and the significance of dyslipoproteinemia in chronic HCV infection with regard to abnormal apolipoproteins.

Transmembrane 6 superfamily member 2 gene E167K variant impacts on steatosis and liver damage in chronic hepatitis C patients

Steatosis and inherited host factors influence liver damage progression in chronic hepatitis C (CHC). The transmembrane 6 superfamily member 2 (TM6SF2) gene E167K variant increases liver fat and risk of progressive steatohepatitis by interfering with lipoprotein secretion. Our aim was to determine whether the E167K variant affects histological severity of steatosis, necroinflammation, and fibrosis in a cross-sectional cohort of 815 Italian therapy-naïve CHC patients. The association with clinically significant fibrosis was replicated in 645 Swiss/German patients. The TM6SF2 E167K variant was genotyped by TaqMan assays, steatosis graded according to the nonalcoholic fatty liver disease activity score, and necroinflammation and fibrosis graded and staged according to Ishak in Italian, and to Metavir in Swiss/German patients. The E167K variant was detected in 69 (9%) Italian patients and was associated with more severe steatosis, independently of confounders (P = 0.038). The association between E167K and steatosis severity was present in patients not infected by genotype 3 (G3) HCV (P = 0.031), but not in those infected by G3 HCV (P = 0.58). Furthermore, the E167K variant was associated with more severe necroinflammation (Ishak grade; adjusted P = 0.037) and nearly associated with more severe fibrosis (Ishak stage; adjusted P = 0.058). At multivariate logistic regression analysis, the E167K variant was independently associated with histologically probable or definite cirrhosis (Ishak stage S6; odds ratio [OR]: 2.19; 95% confidence interval [CI]: 1.18-3.93; P = 0.010). After further conditioning for steatosis and necroinflammation, the E167K variant remained associated with cirrhosis (OR, 3.15; 95% CI: 1.60-5.99; P < 0.001). In Swiss/German patients, the E167K variant was independently associated with clinically significant fibrosis Metavir stage F2-F4 (OR, 1.81; 95% CI: 1.12-3.02; P = 0.016).

CONCLUSION

TM6SF2 E167K variant impacts on steatosis severity and is associated with liver damage and fibrosis in patients with CHC.

MicroRNA-122 associates with serum apolipoprotein B but not liver fibrosis markers in CHC genotype 1 infection

miR-122 is the predominant liver miRNA that regulates hepatic lipid metabolism and inflammation. Hepatitis C virus (HCV) modulates host intracellular lipid metabolism. HCV stability and propagation also depend on an interaction between virus and miR-122. Our aims were to examine the associations between miR-122, apolipoproteins, and serum makers of fibrosis in chronic hepatitis C (CHC) patients. We evaluated baseline sera from 36 CHC genotype 1 patients who completed the Phase IIa study of miravirsen (LNA oligonucleotide targeting miR-122). Samples were assessed for liver transaminases, IL 28B genotype, IP-10, and lipid profiles. The noninvasive markers of liver fibrosis, APRI, and FIB-4, were calculated using standard formulae. miR-122 levels were measured using RT-PCR and expressed as fold-change compared to normal healthy controls. CHC patients were mostly male (61%) with mean age 47.5 ± 11.6 years. Patients with higher ApoB (ApoB/ULN ≥ 0.5) has significantly lower miR-122 levels in compared to patients with lower ApoB (ApoB/ULN < 0.5). (8.28 ± 6.23 vs. 16.28 ± 13.71; P = 0.02). There were no similar associations between miR-122 and ApoA-1 or between HCV RNA and lipoproteins. There were no differences in miR-122 levels between patients with different stages of fibrosis determined by APRI or FIB-4. Patients with lower ApoB had higher serum miR-122 levels. However, we cannot identify significant association between miR-122, ApoA-1, or fibrosis markers in this small cohort of CHC genotype 1 patients. The mechanism of HCV dyslipidemia is complex and could partly relate to the effect of miR-122 on lipid metabolism which requires further evaluation in a larger study.

The missing pieces of the HCV entry puzzle

The past decade has witnessed steady and rapid progress in HCV research, which has led to the recent breakthrough in therapies against this significant human pathogen. Yet a deeper understanding of the life cycle of the virus is required to develop more affordable treatments and to advance vaccine design. HCV entry presents both a challenge for scientific research and an opportunity for alternative intervention approaches, owning to its highly complex nature and the myriad of players involved. More than half a dozen cellular proteins are implicated in HCV entry; and a more definitive picture regarding the structures of the glycoproteins is emerging. A role of apolipoproteins in HCV entry has also been established. Still, major questions remain, and the answers to these, which we summarize in this review, will hopefully close the gaps in our understanding and complete the puzzle that is HCV entry.

PCSK9, apolipoprotein E and lipoviral particles in chronic hepatitis C genotype 3: evidence for genotype-specific regulation of lipoprotein metabolism

BACKGROUND & AIMS

Hepatitis C virus (HCV) associates with lipoproteins to form "lipoviral particles" (LVPs) that can facilitate viral entry into hepatocytes. Initial attachment occurs via heparan sulphate proteoglycans and low-density lipoprotein receptor (LDLR); CD81 then mediates a post-attachment event. Proprotein convertase subtilisin kexin type 9 (PCSK9) enhances the degradation of the LDLR and modulates liver CD81 levels. We measured LVP and PCSK9 in patients chronically infected with HCV genotype (G)3. PCSK9 concentrations were also measured in HCV-G1 to indirectly examine the role of LDLR in LVP clearance.

METHODS

HCV RNA, LVP (d<1.07g/ml) and non-LVP (d>1.07g/ml) fractions, were quantified in patients with HCV-G3 (n=39) by real time RT-PCR and LVP ratios (LVPr; LVP/(LVP+non-LVP)) were calculated. Insulin resistance (IR) was assessed using the homeostasis model assessment of IR (HOMA-IR). Plasma PCSK9 concentrations were measured by ELISA in HCV-G3 and HCV-G1 (n=51).

RESULTS

In HCV-G3 LVP load correlated inversely with HDL-C (r=-0.421; p=0.008), and apoE (r=-0.428; p=0.013). The LVPr varied more than 35-fold (median 0.286; range 0.027 to 0.969); PCSK9 was the strongest negative predictor of LVPr (R(2)=16.2%; p=0.012). HOMA-IR was not associated with LVP load or LVPr. PCSK9 concentrations were significantly lower in HCV-G3 compared to HCV-G1 (p<0.001). PCSK9 did not correlate with LDL-C in HCV-G3 or G1.

CONCLUSIONS

The inverse correlation of LVP with apoE in HCV-G3, compared to the reverse in HCV-G1 suggests HCV genotype-specific differences in apoE mediated viral entry. Lower PCSK9 and LDL concentrations imply upregulated LDLR activity in HCV-G3.

Association of PNPLA3 I148M Variant With Chronic Viral Hepatitis, Autoimmune Liver Diseases and Outcomes of Liver Transplantation

CONTEXT

The PNPLA3 I148M variant has been recognized as a genetic determinant of liver fat content and a genetic risk factor of liver damage progression associated with steatohepatitis. The I148M variant is associated with many chronic liver diseases. However, its potential association with inflammatory and autoimmune liver diseases has not been established.

EVIDENCE ACQUISITION

We systemically reviewed the potential associations of I148M variant with chronic viral hepatitis, autoimmune liver diseases and the outcome of liver transplantation, explored the underlying molecular mechanisms and tried to translate them into more individualized decision-making and personalized medicine.

RESULTS

There were associations between I148M variant and chronic viral hepatitis and autoimmune liver diseases and differential associations of I148M variant in donors and recipients with post-liver transplant outcomes. I148M variant may activate the development of steatosis caused by host metabolic disorders in chronic viral hepatitis, but few researches were found to illustrate the mechanisms in autoimmune liver diseases. The peripherally mediated mechanism (via extrahepatic adipose tissue) may play a principal role in triglyceride accumulation regardless of adiponutrin activity in the graft liver.

CONCLUSIONS

Evidences have shown the associations between I148M variant and mentioned diseases. I148M variant induced steatosis may be involved in the mechanism of chronic viral hepatitis and genetic considered personalized therapies, especially for PSC male patients. It is also crucial to pay attention to this parameter in donor selection and prognosis estimation in liver transplantation.

[Roles of lipoprotein and apolipoprotein in HCV infection]

Although chronic infection of hepatitis C virus (HCV) induces disorders of lipid metabolism, HCV is known to utilize lipid metabolism for efficient propagation in the liver. Due to the morphological and physiological similarities of HCV particles to lipoproteins, lipid-associated HCV particles are named lipoviroparticles. Previous reports have shown that lipoprotein receptors or cholesterol transporter participate in the entry of lipoviroparticles. In addition, recent analyses revealed that exchangeable apolipoproteins directly interact with the viral membrane to generate infectious HCV particles. In this review, we would like to discuss about involvement of lipoprotein and apolipoprotein in HCV lifecycle.

Depressive symptoms in chronic hepatitis C are associated with plasma apolipoprotein E deficiency

Neuro-psychiatric and cognitive disorders are frequent in patients with chronic hepatitis C (CHC) virus (HCV) infection which adversely impact quality of life, antiviral treatment adherence and outcome. HCV has neurotrophic properties and affects lipid metabolism, essential for cognitive function. We evaluated the relationship of lipid profiles with depression and anxiety symptoms and the effects of 12-weeks of therapy with fluvastatin and omega-3 ethyl esters (n-3 PUFA) in a randomised pilot study of CHC prior non-responders. Participants (n = 60) had fasting lipid profiles and assessment of depression and anxiety symptoms using the Hospital Anxiety and Depression Scale (HADS) questionnaire at each study visit. At screening 26/60 (43 %) had HADS-A score ≥8 and 13/60 (22 %) had HADS-D scores ≥8. Depressed patients had significantly lower apolipoprotein-E concentrations (30 mg/l vs 39 mg/l, P = 0.029) than those without depression and a tendency toward lower total cholesterol (3.8 vs 4.4 mmol/l, P = 0.053). 3 patients discontinued lipid-modifying treatment because of worsening depression. However, there was a small but significant improvement in anxiety symptoms after 12-weeks of high-dose (2-4 g daily) n-3 PUFA. In conclusion, depression in CHC is associated with plasma apoE deficiency. We postulate that apoE deficiency disrupts blood brain barrier integrity to promote HCV infection of the CNS. High-dose n-PUFAs may alleviate anxiety in some CHC patients but the use of lipid lowering therapy must be balanced against risks of worsening depression.

Interaction between PNPLA3 I148M variant and age at infection in determining fibrosis progression in chronic hepatitis C

Background and Aims

The PNPLA3 I148M sequence variant favors hepatic lipid accumulation and confers susceptibility to hepatic fibrosis and hepatocellular carcinoma. The aim of this study was to estimate the effect size of homozygosity for the PNPLA3 I148M variant (148M/M) on the fibrosis progression rate (FPR) and the interaction with age at infection in chronic hepatitis C (CHC).

Methods

FPR was estimated in a prospective cohort of 247 CHC patients without alcohol intake and diabetes, with careful estimation of age at infection and determination of fibrosis stage by Ishak score.

Results

Older age at infection was the strongest determinant of FPR (p<0.0001). PNPLA3 148M/M was associated with faster FPR in individuals infected at older age (above the median, 21 years; −0.64±0.2, n = 8 vs. −0.95±0.3, n = 166 log₁₀ FPR respectively; p = 0.001; confirmed for lower age thresholds, p<0.05), but not in those infected at younger age (p = ns). The negative impact of PNPLA3 148M/M on fibrosis progression was more marked in subjects at risk of altered hepatic lipid metabolism (those with grade 2–3 steatosis, genotype 3, and overweight; p<0.05). At multivariate analysis, PNPLA3 148M/M was associated with FPR (incremental effect 0.08±0.03 log₁₀ fibrosis unit per year; p = 0.022), independently of several confounders, and there was a significant interaction between 148M/M and older age at infection (p = 0.025). The association between 148M/M and FPR remained significant even after adjustment for steatosis severity (p = 0.032).

Conclusions

We observed an interaction between homozygosity for the PNPLA3 I148M variant and age at infection in determining fibrosis progression in CHC patients.

Investigating the antiviral role of cell death-inducing DFF45-like effector B in HCV replication

Cell-death-inducing DFF45-like effector B (CIDEB) is an apoptotic host factor, which was recently found to also regulate hepatic lipid homeostasis. Herein we delineate the relevance of these dual roles of CIDEB in apoptosis and lipid metabolism in the context of hepatitis C virus (HCV) replication. We demonstrate that HCV upregulates CIDEB expression in human serum differentiated hepatoma cells. CIDEB overexpression inhibits HCV replication in HCV replicon expressing Huh7.5 cells, while small interfering RNA knockdown of CIDEB expression in human serum differentiated hepatoma cells promotes HCV replication and secretion of viral proteins. Furthermore, we characterize a CIDEB mutant, KRRA, which is deficient in lipid droplet clustering and fusion and demonstrate that CIDEB-mediated inhibition of HCV is independent of the protein's lipid droplet fusogenic role. Our results suggest that higher levels of CIDEB expression, which favour an apoptotic role for the host factor, inhibit HCV. Collectively, our data demonstrate that CIDEB can act as an anti-HCV host factor and contribute to altered triglyceride homeostasis.

Omega-3 fatty acids and/or fluvastatin in hepatitis C prior non-responders to combination antiviral therapy - a pilot randomised clinical trial

BACKGROUND & AIMS

Hepatitis C virus (HCV) utilises cholesterol and lipoprotein metabolism for replication and infectivity. Statins and omega-3 (n-3) polyunsaturated fatty acids (PUFA) have been shown to have antiviral properties in vitro. This open label pilot study evaluated the efficacy of fluvastatin (Lescol(®) 40-80 mg) and n-3 PUFA (Omacor(®) 1 g and 2-4 g) on HCV-RNA and lipoviral particles (LVP) in difficult to treat prior non-responders.

METHODS

Patients (n = 60) were randomly allocated in a factorial design to: no active drug; low-dose n-3 PUFA; high-dose n-3 PUFA; fluvastatin; low-dose n-3 PUFA + fluvastatin; or high-dose n-3 PUFA + fluvastatin. 50/60 completed study drugs for 12 weeks and followed up to week 24. Comparison was made between fluvastatin (n = 24) vs no fluvastatin (n = 26) and n-3 PUFA high-dose (n = 17) vs low-dose (n = 17) vs none (n = 16). The primary outcomes were change in total HCV-RNA, LVP and ALT at week 12 compared with baseline. Secondary outcome was change in interferon-gamma-inducible protein-10 (IP10) as a measure of interferon activation.

RESULTS

35% had compensated cirrhosis and 45% were prior null responders. There was no significant change in total HCV RNA, LVP, non-LVP or LVP ratio in patients receiving fluvastatin or n-3 PUFAs. ALT was not significantly different in those treated with fluvastatin or n-3 PUFAs. 12 weeks of low-dose n-3 PUFA decreased median IP10 concentration by -39 pg/ml (-111, 7.0 pg/ml Q1-Q3).

CONCLUSIONS

Fluvastatin and n-3 PUFAs have no effect on plasma HCV-RNA or LVP. The effect of low-dose n-3 PUFA on IP10 warrants further prospective evaluation as a supplemental therapy to enhance interferon sensitivity.

New pyrazolobenzothiazine derivatives as hepatitis C virus NS5B polymerase palm site I inhibitors

We have previously identified the pyrazolobenzothiazine scaffold as a promising chemotype against hepatitis C virus (HCV) NS5B polymerase, a validated and promising anti-HCV target. Herein we describe the design, synthesis, enzymatic, and cellular characterization of new pyrazolobenzothiazines as anti-HCV inhibitors. The binding site for a representative derivative was mapped to NS5B palm site I employing a mutant counterscreen assay, thus validating our previous in silico predictions. Derivative 2b proved to be the best selective anti-HCV derivative within the new series, exhibiting a IC50 of 7.9 μM against NS5B polymerase and antiviral effect (EC50 = 8.1 μM; EC90 = 23.3 μM) coupled with the absence of any antimetabolic effect (CC50 > 224 μM; SI > 28) in a cell based HCV replicon system assay. Significantly, microscopic analysis showed that, unlike the parent compounds, derivative 2b did not show any significant cell morphological alterations. Furthermore, since most of the pyrazolobenzothiazines tested altered cell morphology, this undesired aspect was further investigated by exploring possible perturbation of lipid metabolism during compound treatment.

Up-regulation of the ATP-binding cassette transporter A1 inhibits hepatitis C virus infection

Hepatitis C virus (HCV) establishes infection using host lipid metabolism pathways that are thus considered potential targets for indirect anti-HCV strategies. HCV enters the cell via clathrin-dependent endocytosis, interacting with several receptors, and virus-cell fusion, which depends on acidic pH and the integrity of cholesterol-rich domains of the hepatocyte membrane. The ATP-binding Cassette Transporter A1 (ABCA1) mediates cholesterol efflux from hepatocytes to extracellular Apolipoprotein A1 and moves cholesterol within cell membranes. Furthermore, it generates high-density lipoprotein (HDL) particles. HDL protects against arteriosclerosis and cardiovascular disease. We show that the up-regulation of ABCA1 gene expression and its cholesterol efflux function in Huh7.5 hepatoma cells, using the liver X receptor (LXR) agonist GW3965, impairs HCV infection and decreases levels of virus produced. ABCA1-stimulation inhibited HCV cell entry, acting on virus-host cell fusion, but had no impact on virus attachment, replication, or assembly/secretion. It did not affect infectivity or properties of virus particles produced. Silencing of the ABCA1 gene and reduction of the specific cholesterol efflux function counteracted the inhibitory effect of the GW3965 on HCV infection, providing evidence for a key role of ABCA1 in this process. Impaired virus-cell entry correlated with the reorganisation of cholesterol-rich membrane microdomains (lipid rafts). The inhibitory effect could be reversed by an exogenous cholesterol supply, indicating that restriction of HCV infection was induced by changes of cholesterol content/distribution in membrane regions essential for virus-cell fusion. Stimulation of ABCA1 expression by GW3965 inhibited HCV infection of both human primary hepatocytes and isolated human liver slices. This study reveals that pharmacological stimulation of the ABCA1-dependent cholesterol efflux pathway disrupts membrane cholesterol homeostasis, leading to the inhibition of virus–cell fusion and thus HCV cell entry. Therefore besides other beneficial roles, ABCA1 might represent a potential target for HCV therapy.

Lipidomic profiling of plasma in patients with chronic hepatitis C infection

Chronic hepatitis C virus (HCV) infection is a global health issue. Although its progression is reported to be closely associated with lipids, the way in which the plasma lipidome changes during the development of chronic HCV infection in humans is currently unknown. Using an improved quantitative high-throughput lipidomic platform, we profiled 284 lipids in human plasma samples obtained from healthy controls (n = 11) and patients with chronic HCV infection (n = 113). The intrahepatic inflammation grade (IG) of liver tissue was determined by biopsy. Two types of mass spectrometers were integrated into a single lipidomic platform with a wide dynamic range. Compared with previous methods, the performance of this method was significantly improved in terms of both the number of target sphingolipids identified and the specificity of the high-resolution mass spectrometer. As a result, 44 sphingolipids, one diacylglycerol, 43 triglycerides, 24 glycerophosphocholines, and 5 glycerophospho-ethanolamines were successfully identified and quantified. The lipid profiles of individuals with chronic HCV infection were significantly different from those of healthy individuals. Several lipids showed significant differences between mild and severe intrahepatic inflammation grades, indicating that they could be utilized as novel noninvasive indicators of intrahepatic IG. Using multivariate analysis, healthy controls could be discriminated from HCV patients based on their plasma lipidome; however, patients with different IGs were not well discriminated. Based on these results, we speculate that variations in lipid composition arise as a result of HCV infection, and are caused by HCV-related digestive system disorders rather than progression of the disease.

Hepatitis C and lipid metabolism, hepatic steatosis, and NAFLD: still important in the era of direct acting antiviral therapy?

Chronic hepatitis C (CHC) and nonalcoholic fatty liver disease (NAFLD) have an individual prevalence of 1.8-3% and at least 30%, respectively, in the United States. It is therefore not surprising that there is overlap between these two common chronic liver diseases, although the relationship appears to go beyond isolated co-existence. Hepatic steatosis is a common feature of CHC infection and can be related to both metabolic and viral specific factors. Steatosis in the setting of nongenotype 3 CHC has been predictive of response to therapy prior to the advent of the direct acting antiviral medications (DAAs). Similarly, lipid metabolism appears important in response to CHC treatment. The pathways for both lipid homeostasis and NAFLD as it pertains to CHC infection as well as the utilization of statin therapy in CHC infection will be reviewed with a focus on the relevance of these topics in the era of DAA therapy.

PNPLA3 I148M polymorphism and progressive liver disease

The 148 Isoleucine to Methionine protein variant (I148M) of patatin-like phospholipase domain-containing 3 (PNPLA3), a protein is expressed in the liver and is involved in lipid metabolism, has recently been identified as a major determinant of liver fat content. Several studies confirmed that the I148M variant predisposes towards the full spectrum of liver damage associated with fatty liver: from simple steatosis to steatohepatitis and progressive fibrosis. Furthermore, the I148M variant represents a major determinant of progression of alcohol related steatohepatitis to cirrhosis, and to influence fibrogenesis and related clinical outcomes in chronic hepatitis C virus hepatitis, and possibly chronic hepatitis B virus hepatitis, hereditary hemochromatosis and primary sclerosing cholangitis. All in all, studies suggest that the I148M polymorphism may represent a general modifier of fibrogenesis in liver diseases. Remarkably, the effect of the I148M variant on fibrosis was independent of that on hepatic steatosis and inflammation, suggesting that it may affect both the quantity and quality of hepatic lipids and the biology of non-parenchymal liver cells besides hepatocytes, directly promoting fibrogenesis. Therefore, PNPLA3 is a key player in liver disease progression. Assessment of the I148M polymorphism will possibly inform clinical practice in the future, whereas the determination of the effect of the 148M variant will reveal mechanisms involved in hepatic fibrogenesis.

Modulation of fatty acid synthase enzyme activity and expression during hepatitis C virus replication

The hepatitis C virus (HCV) induces alterations of host cells to facilitate its life cycle. Fatty acid synthase (FASN) is a multidomain enzyme that plays a key role in the biosynthesis of fatty acids and is upregulated during HCV infection. Herein, we applied activity-based protein profiling (ABPP) that allows for the identification of differentially active enzymes in complex proteomic samples, to study the changes in activity of FASN during HCV replication. For this purpose, we used an activity-based probe based on the FASN inhibitor Orlistat, and observed an increase in the activity of FASN in the presence of a subgenomic and a genomic HCV replicon as well as in chimeric SCID/Alb-uPA mice infected with HCV genotype 1a. To study the molecular basis for this increase in FASN activity, we overexpressed individual HCV proteins in Huh7 cells and observed increased expression and activity of FASN in the presence of core and NS4B, as measured by western blots and ABPP, respectively. Triglyceride levels were also elevated in accordance with FASN expression and activity. Lastly, immunofluorescence and ABPP imaging analyses demonstrated that while the abundance and activity of FASN increases significantly in the presence of HCV, its localization does not change. Together these data suggest that the HCV-induced production of fatty acids and neutral lipids is provided by an increase in FASN abundance and activity that is sufficient to allow HCV propagation without transporting FASN to the replication complexes.

Understanding the hepatitis C virus life cycle paves the way for highly effective therapies

More than two decades of intense research has provided a detailed understanding of hepatitis C virus (HCV), which chronically infects 2% of the world's population. This effort has paved the way for the development of antiviral compounds to spare patients from life-threatening liver disease. An exciting new era in HCV therapy dawned with the recent approval of two viral protease inhibitors, used in combination with pegylated interferon-α and ribavirin; however, this is just the beginning. Multiple classes of antivirals with distinct targets promise highly efficient combinations, and interferon-free regimens with short treatment duration and fewer side effects are the future of HCV therapy. Ongoing and future trials will determine the best antiviral combinations and whether the current seemingly rich pipeline is sufficient for successful treatment of all patients in the face of major challenges, such as HCV diversity, viral resistance, the influence of host genetics, advanced liver disease and other co-morbidities.

Hepatitis C virus and lipids in the era of direct acting antivirals (DAAs)

The six different HCV-genotypes have marked differences in response to therapy with pegylated interferon-α and ribavirin. The introduction of the direct acting antiviral (DAA) protease inhibitors, telaprevir and boceprevir in combination with pegylated interferon-α and ribavirin has become the new standard of care for genotype 1 infection. Several host factors associated with response to pegylated interferon-α and ribavirin are not as important in predicting response to triple therapy, and yet low-density lipoprotein cholesterol (LDLC) and statin use remain important associations of outcome with DAAs. This review focuses on the clinical associations between lipids and treatment response to interferon based antiviral treatments. We consider how understanding the interactions of HCV and host lipid metabolism remains relevant in the era of DAAs for genotype 1 infection and for treatment of non-genotype 1 chronic hepatitis C.

Lipoprotein receptors and lipid enzymes in hepatitis C virus entry and early steps of infection

Viruses are obligate intracellular agents that depend on host cells for successful propagation, hijacking cellular machineries to their own profit. The molecular interplay between host factors and invading viruses is a continuous coevolutionary process that determines viral host range and pathogenesis. The hepatitis C virus (HCV) is a strictly human pathogen, causing chronic liver injuries accompanied by lipid disorders. Upon infection, in addition to protein-protein and protein-RNA interactions usual for such a positive-strand RNA virus, HCV relies on protein-lipid interactions at multiple steps of its life cycle to establish persistent infection, making use of hepatic lipid pathways. This paper focuses on lipoproteins in HCV entry and on receptors and enzymes involved in lipid metabolism that HCV exploits to enter hepatocytes.