Ethanol facilitates hepatitis C virus replication via up-regulation of GW182 and heat shock protein 90 in human hepatoma cells

The Mechanisms of miRNAs on Target Regulation and their Recent Advances in Atherosclerosis

miRNAs are crucial regulators in a variety of physiological and pathological processes, while their regulation mechanisms were usually described as negatively regulating gene expression by targeting the 3'-untranslated region(3'-UTR) of target gene miRNAs through seed sequence in tremendous studies. However, recent evidence indicated the existence of non-canonical mechanisms mediated by binding other molecules besides mRNAs. Additionally, accumulating evidence showed that functions of intracellular and intercellular miRNAs exhibited spatiotemporal patterns. Considering that detailed knowledge of the miRNA regulating mechanism is essential for understanding the roles and further clinical applications associated with their dysfunction and dysregulation, which is complicated and not fully clarified. Based on that, we summarized the recently reported regulation mechanisms of miRNAs, including recognitions, patterns of actions, and chemical modifications. And we also highlight the novel findings of miRNAs in atherosclerosis progression researches to provide new insights for non-coding RNA-based therapy in intractable diseases.

Celastrol attenuates hepatitis C virus translation and inflammatory response in mice by suppressing heat shock protein 90β

Hepatitis C virus (HCV) infection is one of the major factors to trigger a sustained hepatic inflammatory response and hence hepatocellular carcinoma (HCC), but direct-acting-antiviral (DAAs) was not efficient to suppress HCC development. Heat shock protein 90 kDa (HSP90) is highly abundant in different types of cancers, and especially controls protein translation, endoplasmic reticulum stress, and viral replication. In this study we investigated the correlation between the expression levels of HSP90 isoforms and inflammatory response marker NLRP3 in different types of HCC patients as well as the effect of a natural product celastrol in suppression of HCV translation and associated inflammatory response in vivo. We identified that the expression level of HSP90β isoform was correlated with that of NLRP3 in the liver tissues of HCV positive HCC patients (R2 = 0.3867, P < 0.0101), but not in hepatitis B virus-associated HCC or cirrhosis patients. We demonstrated that celastrol (3, 10, 30 μM) dose-dependently suppressed the ATPase activity of both HSP90α and HSP90β, while its anti-HCV activity was dependent on the Ala47 residue in the ATPase pocket of HSP90β. Celastrol (200 nM) halted HCV internal ribosomal entry site (IRES)-mediated translation at the initial step by disrupting the association between HSP90β and 4EBP1. The inhibitory activity of celastrol on HCV RNA-dependent RNA polymerase (RdRp)-triggered inflammatory response also depended on the Ala47 residue of HSP90β. Intravenous injection of adenovirus expressing HCV NS5B (pAde-NS5B) in mice induced severe hepatic inflammatory response characterized by significantly increased infiltration of immune cells and hepatic expression level of Nlrp3, which was dose-dependently ameliorated by pretreatment with celastrol (0.2, 0.5 mg/kg, i.p.). This study reveals a fundamental role of HSP90β in governing HCV IRES-mediated translation as well as hepatic inflammation, and celastrol as a novel inhibitor of HCV translation and associated inflammation by specifically targeting HSP90β, which could be developed as a lead for the treatment of HSP90β positive HCV-associated HCC.

Shedding Lights on the Extracellular Vesicles as Functional Mediator and Therapeutic Decoy for COVID-19

COVID-19 is an infectious disease caused by the novel coronavirus (SARS-CoV-2) that first appeared in late 2019 and has since spread across the world. It is characterized by symptoms such as fever, cough, and shortness of breath and can lead to death in severe cases. To help contain the virus, measures such as social distancing, handwashing, and other public health measures have been implemented. Vaccine and drug candidates, such as those developed by Pfizer/BioNTech, AstraZeneca, Moderna, Novavax, and Johnson & Johnson, have been developed and are being distributed worldwide. Clinical trials for drug treatments such as remdesivir, dexamethasone, and monoclonal antibodies are underway and have shown promising results. Recently, exosomes have gained attention as a possible mediator of the COVID-19 infection. Exosomes, small vesicles with a size of around 30-200 nm, released from cells, contain viral particles and other molecules that can activate the immune system and/or facilitate viral entry into target cells. Apparently, the role of exosomes in eliciting various immune responses and causing tissue injury in COVID-19 pathogenesis has been discussed. In addition, the potential of exosomes as theranostic and therapeutic agents for the treatment of COVID-19 has been elaborated.

Biomimetic material degradation for synergistic enhanced therapy by regulating endogenous energy metabolism imaging under hypothermia

Inefficient tumour treatment approaches often cause fatal tumour metastases. Here, we report a biomimetic multifunctional nanoplatform explicitly engineered with a Co-based metal organic framework polydopamine heterostructure (MOF-PDA), anethole trithione (ADT), and a macrophage membrane. Co-MOF degradation in the tumour microenvironment releases Co²⁺, which results in the downregulation of HSP90 expression and the inhibition of cellular heat resistance, thereby improving the photothermal therapy effect of PDA. H₂S secretion after the enzymatic hydrolysis of ADT leads to high-concentration gas therapy. Moreover, ADT changes the balance between nicotinamide adenine dinucleotide/flavin adenine dinucleotide (NADH/FAD) during tumour glycolysis. ATP synthesis is limited by NADH consumption, which triggers a certain degree of tumour growth inhibition and results in starvation therapy. Potentiated 2D/3D autofluorescence imaging of NADH/FAD is also achieved in liquid nitrogen and employed to efficiently monitor tumour therapy. The developed biomimetic nanoplatform provides an approach to treat orthotopic tumours and inhibit metastasis.

Metal organic frameworks (MOF) coated with mammalian cell membranes have good biocompatibility. Here, the authors develop a cobalt based hydrogen sulphide producing MOF cloaked with a macrophage membrane and show that the subsequent system can reduce tumour growth in mice.

Alcohol Promotes Exosome Biogenesis and Release via Modulating Rabs and miR-192 Expression in Human Hepatocytes

Exosomes are membrane vesicles released by various cell types into the extracellular space under different conditions including alcohol exposure. Exosomes are involved in intercellular communication and as mediators of various diseases. Alcohol use causes oxidative stress that promotes exosome secretion. Here, we elucidated the effects of alcohol on exosome biogenesis and secretion using human hepatocytes. We found that alcohol treatment induces the expression of genes involved in various steps of exosome formation. Expression of Rab proteins such as Rab1a, Rab5c, Rab6, Rab10, Rab11, Rab27a and Rab35 were increased at the mRNA level in primary human hepatocytes after alcohol treatment. Rab5, Rab6 and Rab11 showed significant induction in the livers of patients with alcohol-associated liver disease. Further, alcohol treatment also led to the induction of syntenin, vesicle-associated membrane proteins (VAMPs), and syntaxin that all play various roles in exosome biogenesis and secretion. VAMP3, VAMP5, VAPb, and syntaxin16 mRNA transcripts were increased in alcohol treated cells and in the livers of alcohol-associated liver disease (ALD) patients. Induction in these genes was associated with increases in exosome secretion in alcohol treated hepatocytes. We found that hepatocyte enriched miR-192 and miR-122 levels were significantly decreased in alcohol treated hepatocytes whereas their levels were increased in the cell-free supernatant. The primary transcripts of miR-192 and miR-122 were reduced in alcohol treated hepatocytes, suggesting alcohol partially affects these miRNAs at the transcriptional level. We found that miR-192 has putative binding sites for genes involved in exosome secretion. Inhibition of miR-192 in human hepatoma cells caused a significant increase in Rab27a, Rab35, syntaxin7 and syntaxin16 and a concurrent increase in exosome secretion, suggesting miR-192 regulates exosomes release in hepatocytes. Collectively, our results reveal that alcohol modulates Rabs, VAMPs and syntaxins directly and partly via miR-192 to induce exosome machinery and release.

Diverse Effects of Exosomes on COVID-19: A Perspective of Progress From Transmission to Therapeutic Developments

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new strain of coronavirus and the causative agent of the current global pandemic of coronavirus disease 2019 (COVID-19). There are currently no FDA-approved antiviral drugs for COVID-19 and there is an urgent need to develop treatment strategies that can effectively suppress SARS-CoV-2 infection. Numerous approaches have been researched so far, with one of them being the emerging exosome-based therapies. Exosomes are nano-sized, lipid bilayer-enclosed structures, share structural similarities with viruses secreted from all types of cells, including those lining the respiratory tract. Importantly, the interplay between exosomes and viruses could be potentially exploited for antiviral drug and vaccine development. Exosomes are produced by virus-infected cells and play crucial roles in mediating communication between infected and uninfected cells. SARS-CoV-2 modulates the production and composition of exosomes, and can exploit exosome formation, secretion, and release pathways to promote infection, transmission, and intercellular spread. Exosomes have been exploited for therapeutic benefits in patients afflicted with various diseases including COVID-19. Furthermore, the administration of exosomes loaded with immunomodulatory cargo in combination with antiviral drugs represents a novel intervention for the treatment of diseases such as COVID-19. In particular, exosomes derived from mesenchymal stem cells (MSCs) are used as cell-free therapeutic agents. Mesenchymal stem cell derived exosomes reduces the cytokine storm and reverse the inhibition of host anti-viral defenses associated with COVID-19 and also enhances mitochondrial function repair lung injuries. We discuss the role of exosomes in relation to transmission, infection, diagnosis, treatment, therapeutics, drug delivery, and vaccines, and present some future perspectives regarding their use for combating COVID-19.

Reticulon-3 modulates the incorporation of replication competent hepatitis C virus molecules for release inside infectious exosomes

Background

Cell released microvesicles specifically, exosomes, play an important role in mediating immunologic escape, treatment resistance, and disease persistence of Hepatitis C virus (HCV) infection. Reports on the molecular compositions of exosomes released by cells under diverse conditions, especially during viral infections, suggest that their cargo contents are not randomly loaded. However, the precise molecular mechanisms directing the selective cargo sorting and loading inside infectious viral exosomes remains elusive.

Aim

To decipher the role of Reticulon 3 (RTN3) in the selective molecular cargo sorting and loading inside infectious viral exosomes during HCV infection.

Methods

We used Huh7 cells–JFH1 HCV infection and HCV Full-Length (FL) replicon systems. Additionally, we analyzed human liver and serum exosome samples from healthy and treatment naïve HCV infected individuals. Our experiments made use of molecular biology and immunology techniques.

Results

HCV infection (JFH1-Huh7 or HCV-FL replicon cells) was associated with increased RTN3L&S isoforms expression in cells and cell released exosomes. Accordingly, increased expression of RTN3L&S was observed in liver and serum exosome samples of HCV infected individuals compared to healthy controls. RNA-ChIP analysis revealed that RTN3L&S interacted with dsHCV RNA. Lentiviral CRISPR/Cas9 mediated knockdown (KD) of RTN3 and plasmid overexpression (OE) of wild type, C- and N-terminal deletion mutants of RTN3L&S in HCV- infected Huh7 cells differentially impacted the cellular release of infectious viral exosomes. RTN3L&S KD significantly decreased, while RTN3S OE significantly increased the number of Huh7 cell-released infectious exosomes. The C-terminal domain of RTN3 interacted with and modulated the loading of dsHCV RNA inside infectious exosomes. Antiviral treatment of HCV infected Huh7 cells reduced virus-induced RTN3L&S expression and attenuated the release of infectious exosomes.

Conclusion

RTN3 constitutes a novel regulator and a potential therapeutic target that mediates the specific loading of infectious viral exosomes.

Cloaked Viruses and Viral Factors in Cutting Edge Exosome-Based Therapies

Extracellular vesicles (EVs) constitute a heterogeneous group of vesicles released by all types of cells that play a major role in intercellular communication. The field of EVs started gaining attention since it was realized that these vesicles are not waste bags, but they carry specific cargo and they communicate specific messages to recipient cells. EVs can deliver different types of RNAs, proteins, and lipids from donor to recipient cells and they can influence recipient cell functions, despite their limited capacity for cargo. EVs have been compared to viruses because of their size, cell entry pathways, and biogenesis and to viral vectors because they can be loaded with desired cargo, modified, and re-targeted. These properties along with the fact that EVs are stable in body fluids, they can be produced and purified in large quantities, they can cross the blood-brain barrier, and autologous EVs do not appear to cause major adverse effects, have rendered them attractive for therapeutic use. Here, we discuss the potential for therapeutic use of EVs derived from virus infected cells or EVs carrying viral factors. We have focused on six major concepts: (i) the role of EVs in virus-based oncolytic therapy or virus-based gene delivery approaches; (ii) the potential use of EVs for developing viral vaccines or optimizing already existing vaccines; (iii) the role of EVs in delivering RNAs and proteins in the context of viral infections and modulating the microenvironment of infection; (iv) how to take advantage of viral features to design effective means of EV targeting, uptake, and cargo packaging; (v) the potential of EVs in antiviral drug delivery; and (vi) identification of novel antiviral targets based on EV biogenesis factors hijacked by viruses for assembly and egress. It has been less than a decade since more attention was given to EV research and some interesting concepts have already been developed. In the coming years, additional information on EV biogenesis, how they are hijacked and utilized by pathogens, and their impact on the microenvironment of infection is expected to indicate avenues to optimize existing therapeutic tools and develop novel approaches.

Cross talk between alcohol-induced oxidative stress and HCV replication

Alcohol consumption exacerbates the pathogenesis of hepatitis C virus (HCV) infection and aggravates disease consequences in alcohol-abusing patients. Although the exact reasons by which alcohol consumption affects several cellular pathways in liver cells are not clear, they might be partially attributed to the ability of alcohol to further suppress the innate immunity, modulation of autophagy and also its relationship with reactive oxygen species (ROS) generation. To evaluate these issues, Huh7 cells harboring HCV replicon and Cytochrome p450 (CYP2E1) plasmid were exposed to ethanol and mRNA expression of Beclin-1, interferon-stimulated gene15 (ISG15) genes and HCV NS5B for two different times were relatively quantitated. ROS was determined by flow cytometry. The results showed that alcohol treatment in a short time caused an increase in HCV NS5B and Beclin-1 mRNA and decreased ISG 15 mRNA. Long-lasting alcohol treatment increased ROS production in Huh-7 cells and HCV replication was reduced. In conclusion, acute alcohol treatment might contribute to increase HCV replication by interference in innate immunity and induction of autophagy. Chronic alcohol treatment caused oxidative stress, which disrupts autophagy and thereby increased the rate of Huh7 cell injury.

Impact of hepatitis C virus and alcohol, alone and combined, on the unfolded protein response in primary human hepatocytes

Hepatitis C virus (HCV) infection and alcohol abuse are leading causes of chronic liver disease and frequently coexist in patients. The unfolded protein response (UPR), a cellular stress response ranging along a spectrum from cytoprotection to apoptosis commitment, has emerged as a major contributor to human diseases including liver injuries. However, the literature contains conflicting reports as to whether HCV and ethanol activate the UPR and which UPR genes are involved. Here we have used primary human hepatocytes (PHH) to reassess this issue and address combined impacts. In this physiologically relevant model, either stressor activated a chronic complete UPR. However, the levels of UPR gene induction were only modest in the case of HCV infection. Moreover, when combined to the strong stressor thapsigargin, ethanol exacerbated the activation of pro-apoptotic genes whereas HCV tended to limit the induction of key UPR genes. The UPR resulting from HCV plus ethanol was comparable to that induced by ethanol alone with the notable exception of three pro-survival genes the expressions of which were selectively enhanced by HCV. Interestingly, HCV genome replication was maintained at similar levels in PHH exposed to ethanol. In conclusion, while both HCV and alcohol activate the hepatocellular UPR, only HCV manipulates UPR signalling in the direction of a cytoprotective response, which appears as a viral strategy to spare its own replication.

TNRC6 proteins modulate hepatitis C virus replication by spatially regulating the binding of miR-122/Ago2 complexes to viral RNA

The liver-specific microRNA, miR-122, is an essential host factor for replication of the hepatitis C virus (HCV). miR-122 stabilizes the positive-strand HCV RNA genome and promotes its synthesis by binding two sites (S1 and S2) near its 5' end in association with Ago2. Ago2 is essential for both host factor activities, but whether other host proteins are involved is unknown. Using an unbiased quantitative proteomics screen, we identified the TNRC6 protein paralogs, TNRC6B and TNRC6C, as functionally important but redundant components of the miR-122/Ago2 host factor complex. Doubly depleting TNRC6B and TNRC6C proteins reduced HCV replication in human hepatoma cells, dampening miR-122 stimulation of viral RNA synthesis without reducing the stability or translational activity of the viral RNA. TNRC6B/C were required for optimal miR-122 host factor activity only when S1 was able to bind miR-122, and restricted replication when S1 was mutated and only S2 bound by miR-122. TNRC6B/C preferentially associated with S1, and TNRC6B/C depletion enhanced Ago2 association at S2. Collectively, these data suggest a model in which TNRC6B/C regulate the assembly of miR-122/Ago complexes on HCV RNA, preferentially directing miR-122/Ago2 to S1 while restricting its association with S2, thereby fine-tuning the spatial organization of miR-122/Ago2 complexes on the viral genome.

Effect of ethanol on lipid metabolism

Hepatic lipid metabolism is a series of complex processes that control influx and efflux of not only hepatic lipid pools, but also organismal pools. Lipid homeostasis is usually tightly controlled by expression, substrate supply, oxidation and secretion that keep hepatic lipid pools relatively constant. However, perturbations of any of these processes can lead to lipid accumulation in the liver. Although it is thought that these responses are hepatic arms of the 'thrifty genome', they are maladaptive in the context of chronic fatty liver diseases. Ethanol is likely unique among toxins, in that it perturbs almost all aspects of hepatic lipid metabolism. This complex response is due in part to the large metabolic demand placed on the organ by alcohol metabolism, but also appears to involve more nuanced changes in expression and substrate supply. The net effect is that steatosis is a rapid response to alcohol abuse. Although transient steatosis is largely an inert pathology, the chronicity of alcohol-related liver disease seems to require steatosis. Better and more specific understanding of the mechanisms by which alcohol causes steatosis may therefore translate into targeted therapies to treat alcohol-related liver disease and/or prevent its progression.

miRNA Signature in NAFLD: A Turning Point for a Non-Invasive Diagnosis

Nonalcoholic fatty liver disease (NAFLD) defines a wide pathological spectrum ranging from simple steatosis to nonalcoholic steatohepatitis (NASH) which may predispose to liver cirrhosis and hepatocellular carcinoma. It represents the leading cause of hepatic damage worldwide. Diagnosis of NASH still requires liver biopsy but due to the high prevalence of NAFLD, this procedure, which is invasive, is not practicable for mass screening. Thus, it is crucial to non-invasively identify NAFLD patients at higher risk of progression to NASH and fibrosis. It has been demonstrated that hepatic fat content and progressive liver damage have a strong heritable component. Therefore, genetic variants associated with NAFLD have been proposed as non-invasive markers to be used in clinical practice. However, genetic variability is not completely explained by these common variants and it is possible that many of the phenotypic differences result from gene-environment interactions. Indeed, NAFLD development and progression is also modulated by epigenetic factors, in particular microRNAs (miRNAs), which control at post-transcriptional level many complementary target mRNAs and whose dysregulation has been shown to have high prognostic and predictive value in NAFLD. The premise of the current review is to discuss the role of miRNAs as pathogenic factors, risk predictors and therapeutic targets in NAFLD.

Alcoholic liver fibrosis: detection and treatment

Alcohol consumption is one of the main risks to public health. Alcohol use disorders (AUDs) cause 80% of hepatotoxic deaths, and approximately 50% of cirrhosis is alcohol-related. The acceptable daily intake (ADI) for ethanol is 2.6 g/day, deduced from morbidity and mortality rates due to liver fibrosis. The relative risk of cirrhosis increases significantly for doses above 60 g/day for men and 20 g/day for women over a period of around 10 years. Twenty to 40% of steatosis cases will evolve into steatohepatitis/steatofibrosis, and 8 to 20% will evolve directly into liver cirrhosis. About 20 to 40% of steatohepatitis cases will evolve into cirrhosis, and 4 to 5% into hepatocellular carcinoma. This cascade of events evolves in 5 to 40 years, with the temporal variability caused by the subjects' genetic patterns and associated risk/comorbidity factors. Steatohepatitis should be considered "the rate limiting step:" usually, it can be resolved through abstinence, although for some patients, once this situation develops, it is not substantially modified by abstention and there is a risk of fibrotic evolution. Early detection of fibrosis, obtained by hepatic elastography, is a crucial step in patients with AUDs. Such strategy allows patients to be included in a detoxification program in order to achieve abstention. Drugs such as silybin, metadoxine, and adenosylmethionine can be used. Other drugs, with promising antifibrotic effects, are currently under study. In this review, we discuss clinical and pathogenetic aspects of alcohol-related liver fibrosis and present and future strategies to prevent cirrhosis.

Alcoholic liver disease: A current molecular and clinical perspective

Heavy alcohol use is the cause of alcoholic liver disease (ALD). The ALD spectrum ranges from alcoholic steatosis to steatohepatitis, fibrosis, and cirrhosis. In Western countries, approximately 50% of cirrhosis-related deaths are due to alcohol use. While alcoholic cirrhosis is no longer considered a completely irreversible condition, no effective anti-fibrotic therapies are currently available. Another significant clinical aspect of ALD is alcoholic hepatitis (AH). AH is an acute inflammatory condition that is often comorbid with cirrhosis, and severe AH has a high mortality rate. Therapeutic options for ALD are limited. The established treatment for AH is corticosteroids, which improve short-term survival but do not affect long-term survival. Liver transplantation is a curative treatment option for alcoholic cirrhosis and AH, but patients must abstain from alcohol use for 6 months to qualify. Additional effective therapies are needed. The molecular mechanisms underlying ALD are complex and have not been fully elucidated. Various molecules, signaling pathways, and crosstalk between multiple hepatic and extrahepatic cells contribute to ALD progression. This review highlights established and emerging concepts in ALD clinicopathology, their underlying molecular mechanisms, and current and future ALD treatment options.

Hepatitis C infection substantially reduces survival of alcohol-dependent patients

Background

Heavy alcohol use is associated with life-threatening complications including progressive liver disease. We aimed to analyze the impact of hepatitis C virus (HCV) infection on survival and liver-related death in alcohol-dependent patients.

Patients and methods

This is a longitudinal study in patients seeking treatment of alcohol abuse between 2000 and 2010. Information on alcohol use characteristics, alcoholic liver disease, and HCV infection were obtained at entry. Cumulated mortality and causes of death were ascertained through clinical records and death registry.

Results

A total of 819 patients (81.6% men) underwent ethanol detoxification; age was 44 (inter-quartile range [IQR] 38-51) years; the duration of heavy alcohol use was 14 (IQR 6-24) years; and the alcohol consumption was 190 (IQR 120-250) g/day. The prevalence of HCV infection was 15.8%. There were 129 (16.9%) deaths during 5,117 persons-year (p-y) of follow-up (median follow-up 6.4 [IQR 4.3-9.2] years); 31 (24.6%) deaths were observed among the HCV-positive patients, and 98 (15.4%) deaths were observed among the HCV-negative patients. The mortality rate was significantly (P=0.03) higher among the HCV-positive patients (3.84×100 p-y; 95% confidence interval [CI]: 2.70, 5.46) than among the HCV-negative patients (2.27×100 p-y; 95% CI: 1.86, 2.77). Survival times for the HCV infected patients were 34% shorter (time ratio relative to HCV negative: 0.66; 95% CI: 0.51, 0.86). The main causes of death in the HCV-positive and -negative patients were liver-related mortality (48.4%) and neoplasia (22.4%), respectively. The liver-related mortality was significantly higher among the HCV-positive patients (adjusted sub-distribution hazard ratio [asHR] 3.65; 95% CI: 1.72, 7.78; P=0.001).

Conclusion

HCV infection compromises the survival of patients with alcohol abuse/dependence. The new direct antiviral agents for the treatment of HCV infection may result in better clinical outcomes.

Role of GW182 protein in the cell

GW182 proteins interact directly with the argonaute proteins and constitute key components of miRNA repressor complexes (miRISC) in metazoans. As argonautes are insufficient for silencing they recruit the GW182 s that act as scaffold proteins inducing downstream translational repression, target mRNA deadenylation and exonucleolytic mRNA degradation. Besides their role as part of repressor complexes inside the cell, they function in wide variety of cellular processes as highlighted in this review. The present review summarises and discusses in detail our current knowledge of the GW182 s and their role inside the cell.

Could targeting the heat shock protein 90 revolutionize antiviral therapy?

Traditional antiviral strategies that target viral components are frequently associated with the generation of drug-resistant viruses. Thus, the development of novel antiviral drugs is critical. Hsp90 is a promising broad-spectrum antiviral drug target; however, whether targeting Hsp90 will revolutionize antiviral therapy remains ambiguous. Here, we summarize how Hsp90 functions in relation to its interactors, and listed the specific Hsp90 isoforms that participated in the virus life cycle. We also discuss the advantages and challenges of targeting Hsp90, taking into account antiviral activity, toxicity and the likelihood of emergence of drug-resistant viruses. Overall, we highlight that targeting Hsp90 might represent a novel and effective antiviral strategy. However, further studies are required before Hsp90 inhibitors can be used in antiviral therapy.

HSP90: a promising broad-spectrum antiviral drug target

The emergence of antiviral drug-resistant mutants is the most important issue in current antiviral therapy. As obligate parasites, viruses require host factors for efficient replication. An ideal therapeutic target to prevent drug-resistance development is represented by host factors that are crucial for the viral life cycle. Recent studies have indicated that heat shock protein 90 (HSP90) is a crucial host factor that is required by many viruses for multiple phases of their life cycle including viral entry, nuclear import, transcription, and replication. In this review, we summarize the most recent advances regarding HSP90 function, mechanisms of action, and molecular pathways that are associated with viral infection, and provide a comprehensive understanding of the role of HSP90 in the immune response and exosome-mediated viral transmission. In addition, several HSP90 inhibitors have entered clinical trials for specific cancers that are associated with viral infection, which further implies a crucial role for HSP90 in the malignant transformation of virus-infected cells; as such, HSP90 inhibitors exhibit excellent therapeutic potential. Finally, we describe the challenge of developing HSP90 inhibitors as anti-viral drugs.

The effects of alcohol on spontaneous clearance of acute hepatitis C virus infection in females versus males

BACKGROUND

Approximately one quarter of persons exposed to hepatitis C virus (HCV) will spontaneously clear infection. We undertook this study to investigate the impact of alcohol on likelihood of HCV spontaneous viral clearance stratified by sex groups.

METHODS

Pooled data from an international collaboration of prospective observational studies of incident HIV and HCV infection in high-risk cohorts (the InC3 Study) was restricted to 411 persons (or 560.7 person-years of observation) with documented acute HCV infection and data regarding alcohol use. The predictor of interest was self-reported alcohol use at or after estimated date of incident HCV infection and the outcome was HCV spontaneous clearance. Sex stratified Cox proportional hazards models were used to evaluate the association between alcohol and spontaneous clearance, adjusting for age, race/ethnicity, and IFNL4 genotype.

RESULTS

The median age was 28.5 years, 30.4% were women, 87.2% were white, and 71.8% reported alcohol use at or after incident infection. There were 89 (21.6%) cases of spontaneous clearance observed, 39 (31.2%) among women and 50 (17.5%) in men (p<0.01). Overall, spontaneous clearance occurred less frequently among participants who drank alcohol compared to those who did not drink (18.9% v. 28.5%, p=0.03). After adjustment for other covariates, alcohol was significantly and independently associated with lower relative hazards for spontaneous clearance of HCV in women (AHR=0.35; 95% CI: 0.19-0.66; p=0.001) but not in men (AHR=0.63; 95% CI: 0.36-1.09; p=0.10).

CONCLUSION

Results indicate that abstaining from drinking alcohol may increase the likelihood of spontaneous clearance among women.

The Effects of Alcohol on Other Chronic Liver Diseases

Alcohol consumption is often a comorbid condition in other chronic liver diseases. It has been shown to act in synergy to increase liver injury in viral hepatitis, hereditary hemochromatosis, and nonalcoholic fatty liver disease (NAFLD), leading to an increased risk of cirrhosis, hepatocellular carcinoma, and liver-related mortality. Data suggest that modest alcohol consumption may be inversely related to the risk of developing NAFLD and lower rates of progression of NAFLD to nonalcoholic steatohepatitis (NASH). This article reviews data on the relationship between alcohol consumption and other chronic liver diseases.

Versican: a novel modulator of hepatic fibrosis

Little is known about the deposition and turnover of proteoglycans in liver fibrosis, despite their abundance in the extracellular matrix. Versican plays diverse roles in modulating cell behavior in other fibroproliferative diseases, but remains poorly described in the liver. Hepatic fibrosis was induced by carbon tetrachloride treatment of C57BL/6 mice over 4 weeks followed by recovery over a 28-day period. Primary mouse hepatic stellate cells (HSCs) were activated in culture and versican was transiently knocked down in human (LX2) and mouse HSCs. Expression of versican, A Disintegrin-like and Metalloproteinase with Thrombospondin-1 motifs (ADAMTS)-1, -4, -5, -8, -9, -15, and -20, and markers of fibrogenesis were studied using immunohistochemistry, real-time quantitative PCR, and western blotting. Immunohistochemistry showed increased expression of versican in cirrhotic human livers and the mouse model of fibrosis. Carbon tetrachloride treatment led to significant increases in versican expression and the proteoglycanases ADAMTS-5, -9, -15, and -20, alongside TNF-α, α-smooth muscle actin (α-SMA), collagen-1, and TGF-β expression. During recovery, expression of many of these genes returned to control levels. However, expression of ADAMTS-5, -8, -9, and -15 showed delayed increases in expression at 28 days of recovery, which corresponded with decreases in versican V0 and V1 cleavage products (G1-DPEAAE(1401) and G1-DPEAAE(441)). Activation of primary HSCs in vitro significantly increased versican, α-SMA, and collagen-1 expression. Transient knockdown of versican in HSCs led to decreases in markers of fibrogenesis and reduced cell proliferation, without inducing apoptosis. Versican expression increases during HSC activation and liver fibrosis, and proteolytic processing occurs during the resolution of fibrosis. Knockdown studies in vitro suggest a possible role of versican in modulating hepatic fibrogenesis.

Alcoholic liver disease and hepatitis C virus infection

Alcohol consumption and hepatitis C virus (HCV) infection have a synergic hepatotoxic effect, and the coexistence of these factors increases the risk of advanced liver disease. The main mechanisms of this effect are increased viral replication and altered immune response, although genetic predisposition may also play an important role. Traditionally, HCV prevalence has been considered to be higher (up to 50%) in alcoholic patients than in the general population. However, the presence of advanced alcoholic liver disease (ALD) or intravenous drug use (IDU) may have confounded the results of previous studies, and the real prevalence of HCV infection in alcoholic patients without ALD or prior IDU has been shown to be lower. Due to the toxic combined effect of HCV and alcohol, patients with HCV infection should be screened for excessive ethanol intake. Patients starting treatment for HCV infection should be specifically advised to stop or reduce alcohol consumption because of its potential impact on treatment efficacy and adherence and may benefit from additional support during antiviral therapy. This recommendation might be extended to all currently recommended drugs for HCV treatment. Patients with alcohol dependence and HCV infection, can be treated with acamprosate, nalmefene, topiramate, and disulfiram, although baclofen is the only drug specifically tested for this purpose in patients with ALD and/or HCV infection.

Alcoholic liver disease and hepatitis C virus infection

Alcohol consumption and hepatitis C virus (HCV) infection have a synergic hepatotoxic effect, and the coexistence of these factors increases the risk of advanced liver disease. The main mechanisms of this effect are increased viral replication and altered immune response, although genetic predisposition may also play an important role. Traditionally, HCV prevalence has been considered to be higher (up to 50%) in alcoholic patients than in the general population. However, the presence of advanced alcoholic liver disease (ALD) or intravenous drug use (IDU) may have confounded the results of previous studies, and the real prevalence of HCV infection in alcoholic patients without ALD or prior IDU has been shown to be lower. Due to the toxic combined effect of HCV and alcohol, patients with HCV infection should be screened for excessive ethanol intake. Patients starting treatment for HCV infection should be specifically advised to stop or reduce alcohol consumption because of its potential impact on treatment efficacy and adherence and may benefit from additional support during antiviral therapy. This recommendation might be extended to all currently recommended drugs for HCV treatment. Patients with alcohol dependence and HCV infection, can be treated with acamprosate, nalmefene, topiramate, and disulfiram, although baclofen is the only drug specifically tested for this purpose in patients with ALD and/or HCV infection.

Chaperones in hepatitis C virus infection

The hepatitis C virus (HCV) infects approximately 3% of the world population or more than 185 million people worldwide. Each year, an estimated 350000-500000 deaths occur worldwide due to HCV-associated diseases including cirrhosis and hepatocellular carcinoma. HCV is the most common indication for liver transplantation in patients with cirrhosis worldwide. HCV is an enveloped RNA virus classified in the genus Hepacivirus in the Flaviviridae family. The HCV viral life cycle in a cell can be divided into six phases: (1) binding and internalization; (2) cytoplasmic release and uncoating; (3) viral polyprotein translation and processing; (4) RNA genome replication; (5) encapsidation (packaging) and assembly; and (6) virus morphogenesis (maturation) and secretion. Many host factors are involved in the HCV life cycle. Chaperones are an important group of host cytoprotective molecules that coordinate numerous cellular processes including protein folding, multimeric protein assembly, protein trafficking, and protein degradation. All phases of the viral life cycle require chaperone activity and the interaction of viral proteins with chaperones. This review will present our current knowledge and understanding of the role of chaperones in the HCV life cycle. Analysis of chaperones in HCV infection will provide further insights into viral/host interactions and potential therapeutic targets for both HCV and other viruses.

Alcoholic hepatitis and HCV interactions in the modulation of liver disease

Most HCV-infected patients regularly consume alcohol. Alcoholic liver disease (ALD) and chronic hepatitis C virus (HCV) infection together are the most common causes of liver disease worldwide. Although both factors independently cause liver disease, they synergistically promote rapid liver disease progression with devastating outcomes for patients. This review focuses on the prevalence, clinical characteristics and molecular pathophysiologic mechanisms of HCV infection associated with alcohol abuse. Recent findings have centred on the synergistic effect of alcohol and HCV on viral replication, hepatocyte apoptosis, oxidative stress, alcohol-induced 'leaky gut', miR-122 and immune dysregulation. Clinical and basic research findings presented here summarize key scientific findings with the aim of highlighting potential areas for new therapies and identifying ways of optimizing current treatments for alcoholics with HCV infection.

MicroRNAs: Role in Hepatitis C Virus pathogenesis

Hepatitis C virus (HCV) is a global health burden with an estimated 170-200 million peoples chronically infected worldwide. HCV infection remains as an independent risk factor for chronic hepatitis, liver cirrhosis, hepatocellular carcinoma, and a major reason for liver transplantation. Discovery of direct acting antiviral (DAA) drugs have shown promising results with more than 90% success rate in clearing the HCV RNA in patients, although long-term consequences remain to be evaluated. microRNAs (miRNAs) are important players in establishment of HCV infection and target crucial host cellular factors needed for productive HCV replication and augmented cell growth. Altered expression of miRNAs is involved in the pathogenesis associated with HCV infection by controlling signaling pathways such as immune response, proliferation and apoptosis. miRNA is emerging as a means of communication between various cell types inside the liver. There is likely possibility of developing circulating miRNAs as biomarkers of disease progression and can also serve as diagnostic tool with potential of early therapeutic intervention in HCV associated end stage liver disease. This review focuses on recent studies highlighting the contribution of miRNAs in HCV life cycle and their coordinated regulation in HCV mediated liver disease progression.

Hepatitis C, innate immunity and alcohol: friends or foes?

Hepatitis C and alcohol are the most widespread causes of liver disease worldwide. Approximately 80% of patients with a history of hepatitis C and alcohol abuse develop chronic liver injury. Alcohol consumption in hepatitis C virus (HCV)-infected patients exacerbates liver disease leading to rapid progression of fibrosis, cirrhosis and even hepatocellular carcinoma. Hepatocytes are the main sites of HCV-infection and ethanol metabolism, both of which generate oxidative stress. Oxidative stress levels affect HCV replication and innate immunity, resulting in a greater susceptibility for HCV-infection and virus spread in the alcoholic patients. In this review paper, we analyze the effects of ethanol metabolism and other factors on HCV replication. In addition, we illustrate the mechanisms of how HCV hijacks innate immunity and how ethanol exposure regulates this process. We also clarify the effects of HCV and ethanol metabolism on interferon signaling-a crucial point for activation of anti-viral genes to protect cells from virus-and the role that HCV- and ethanol-induced impairments play in adaptive immunity which is necessary for recognition of virally-infected hepatocytes. In conclusion, ethanol exposure potentiates the suppressive effects of HCV on innate immunity, which activates viral spread in the liver and finally, leads to impairments in adaptive immunity. The dysregulation of immune response results in impaired elimination of HCV-infected cells, viral persistence, progressive liver damage and establishment of chronic infection that worsens the outcomes of chronic hepatitis C in alcoholic patients.

MicroRNAs in alcoholic liver disease

Alcoholic liver disease (ALD) is characterized by hepatocyte damage, inflammatory cell activation and increased intestinal permeability leading to the clinical manifestations of alcoholic hepatitis. Selected members of the family of microRNAs are affected by alcohol, resulting in an abnormal miRNA profile in the liver and circulation in ALD. Increasing evidence suggests that mRNAs that regulate inflammation, lipid metabolism and promote cancer are affected by excessive alcohol administration in mouse models of ALD. This communication highlights recent findings in miRNA expression and functions as they relate to the pathogenesis of ALD. The cell-specific distribution of miRNAs, as well as the significance of circulating extracellular miRNAs, is discussed as potential biomarkers. Finally, the prospects of miRNA-based therapies are evaluated in ALD.

miR-122--a key factor and therapeutic target in liver disease

Being the largest internal organ of the human body with the unique ability of self-regeneration, the liver is involved in a wide variety of vital functions that require highly orchestrated and controlled biochemical processes. Increasing evidence suggests that microRNAs (miRNAs) are essential for the regulation of liver development, regeneration and metabolic functions. Hence, alterations in intrahepatic miRNA networks have been associated with liver disease including hepatitis, steatosis, cirrhosis and hepatocellular carcinoma (HCC). miR-122 is the most frequent miRNA in the adult liver, and a central player in liver biology and disease. Furthermore, miR-122 has been shown to be an essential host factor for hepatitis C virus (HCV) infection and an antiviral target, complementary to the standard of care using direct-acting antivirals or interferon-based treatment. This review summarizes our current understanding of the key role of miR-122 in liver physiology and disease, highlighting its role in HCC and viral hepatitis. We also discuss the perspectives of miRNA-based therapeutic approaches for viral hepatitis and liver disease.

MicroRNAs in alcoholic liver disease

Alcoholic liver disease (ALD) is characterized by hepatocyte damage, inflammatory cell activation and increased intestinal permeability leading to the clinical manifestations of alcoholic hepatitis. Selected members of the family of microRNAs are affected by alcohol, resulting in an abnormal miRNA profile in the liver and circulation in ALD. Increasing evidence suggests that mRNAs that regulate inflammation, lipid metabolism and promote cancer are affected by excessive alcohol administration in mouse models of ALD. This communication highlights recent findings in miRNA expression and functions as they relate to the pathogenesis of ALD. The cell-specific distribution of miRNAs, as well as the significance of circulating extracellular miRNAs, is discussed as potential biomarkers. Finally, the prospects of miRNA-based therapies are evaluated in ALD.

Alcohol and HCV: implications for liver cancer

Liver cancers are one of the deadliest known malignancies which are increasingly becoming a major public health problem in both developed and developing countries. Overwhelming evidence suggests a strong role of infection with hepatitis B and C virus (HBV and HCV), alcohol abuse, as well as metabolic diseases such as obesity and diabetes either individually or synergistically to cause or exacerbate the development of liver cancers. Although numerous etiologic mechanisms for liver cancer development have been advanced and well characterized, the lack of definite curative treatments means that gaps in knowledge still exist in identifying key molecular mechanisms and pathways in the pathophysiology of liver cancers. Given the limited success with current therapies and preventive strategies against liver cancer, there is an urgent need to identify new therapeutic options for patients. Targeting HCV and or alcohol-induced signal transduction, or virus-host protein interactions may offer novel therapies for liver cancer. This review summarizes current knowledge on the mechanistic development of liver cancer associated with HCV infection and alcohol abuse as well as highlights potential novel therapeutic strategies.

Apolipoprotein J, a glucose-upregulated molecular chaperone, stabilizes core and NS5A to promote infectious hepatitis C virus virion production

BACKGROUND & AIMS

Hepatitis C virus (HCV) infection leads to glucose abnormality. HCV depends on lipid droplets (LDs) and very-low density lipoproteins for assembly/releasing; however, the components and locations for this process remain unidentified. Apolipoprotein J (ApoJ), upregulated by glucose, functions as Golgi chaperone of secreted proteins and resides abundantly in very-low density lipoproteins. This study investigates the interplay between glucose, ApoJ and HCV virion production.

METHODS

The effects of high glucose on ApoJ expression and HCV production were evaluated with cultivated HuH7.5, primary human hepatocytes, and in treatment naive chronic hepatitis C patients. How ApoJ affects HCV lifecycle was assessed using siRNA knockdown strategy in JFH1 infected and subgenomic replicon cells. The interactions and locations of ApoJ with viral and host components were examined by immunoprecipitation, immunofluorescence and subcellular fractionation experiments.

RESULTS

HCV infection increased ApoJ expression, which in parallel with HCV infectivity was additionally elevated with high glucose treatment. Serum ApoJ correlated positively with fasting blood glucose concentration and HCV-RNA titre in patients. ApoJ silencing reduced intracellular and extracellular HCV infectivity and extracellular HCV-RNA, but accumulated intracellular HCV-RNA in HCV-infected cells. ApoJ interacted with HCV core and NS5A and stabilized the dual protein complex. HCV infection dispersed cytoplasmic ApoJ from the compact zones of the Golgi to encircle LDs, where co-localization of the core, NS5A, HCV-RNA, subcellular markers for LDs, endoplasmic reticulum (ER), Golgi, and membrane contact sites occurred.

CONCLUSIONS

ApoJ facilitates infectious HCV particle production via stabilization of core/NS5A, which might surround LDs at the ER-Golgi membrane contact site.

Exosomes from hepatitis C infected patients transmit HCV infection and contain replication competent viral RNA in complex with Ago2-miR122-HSP90

Antibodies targeting receptor-mediated entry of HCV into hepatocytes confer limited therapeutic benefits. Evidence suggests that exosomes can transfer genetic materials between cells; however, their role in HCV infection remains obscure. Here, we show that exosomes isolated from sera of chronic HCV infected patients or supernatants of J6/JFH1-HCV-infected Huh7.5 cells contained HCV RNA. These exosomes could mediate viral receptor-independent transmission of HCV to hepatocytes. Negative sense HCV RNA, indicative of replication competent viral RNA, was present in exosomes of all HCV infected treatment non-responders and some treatment-naïve individuals. Remarkably, HCV RNA was associated with Ago2, HSP90 and miR-122 in exosomes isolated from HCV-infected individuals or HCV-infected Huh7.5 cell supernatants. Exosome-loading with a miR-122 inhibitor, or inhibition of HSP90, vacuolar H+-ATPases, and proton pumps, significantly suppressed exosome-mediated HCV transmission to naïve cells. Our findings provide mechanistic evidence for HCV transmission by blood-derived exosomes and highlight potential therapeutic strategies.

Inhibition of heat shock protein 90 alleviates steatosis and macrophage activation in murine alcoholic liver injury

BACKGROUND & AIMS

Heat shock protein 90 (hsp90) is an emerging therapeutic target in chronic liver diseases. Hsp90 plays an important role in liver immune cell activation; however its role in alcoholic liver disease (ALD) remains elusive. Here we hypothesize that hsp90 is crucial in alcohol induced steatosis and pro-inflammatory cytokine production. To test this hypothesis, we employed a pharmacological inhibitor of hsp90, 17-DMAG (17-Dimethylamino-ethylamino-17-demethoxygeldanamycin) in an in vivo mouse model of acute and chronic alcoholic liver injury.

METHODS

C57BL/6 mice were given either a single dose of ethanol via oral gavage (acute) or chronically fed alcohol for 2 weeks followed by oral gavage (chronic-binge). 17-DMAG was administered during or at the end of feeding. Liver injury parameters, inflammatory cytokines and lipid metabolism genes were analysed.

RESULTS

Our results reveal increased expression of hsp90 in human and mouse alcoholic livers. In vivo inhibition of hsp90, using 17-DMAG, not only prevented but also alleviated alcoholic liver injury, determined by lower serum ALT, AST and reduced hepatic triglycerides. Mechanistic analysis showed that 17-DMAG decreased alcohol mediated oxidative stress, reduced serum endotoxin, decreased inflammatory cells, and diminished sensitization of liver macrophages to LPS, resulting in downregulation of CD14, NFκB inhibition, and decreased pro-inflammatory cytokine production. Hsp90 inhibition decreased fatty acid synthesis genes via reduced nuclear SREBP-1 and favoured fatty acid oxidation genes via PPARα.

CONCLUSIONS

Inhibition of hsp90 decreased alcohol induced steatosis and pro-inflammatory cytokines and inhibited alcoholic liver injury. Hsp90 is therefore relevant in human alcoholic cirrhosis and a promising therapeutic target in ALD.

A Novel Human Radixin Peptide Inhibits Hepatitis C Virus Infection at the Level of Cell Entry

Hepatitis C virus infection of hepatocytes is a multistep process involving the interaction between viral and host cell molecules. Recently, we identified ezrin-moesin-radixin proteins and spleen tyrosine kinase (SYK) as important host therapeutic targets for HCV treatment development. Previously, an ezrin hinge region peptide (Hep1) has been shown to exert anti-HCV properties in vivo, though its mechanism of action remains limited. In search of potential novel inhibitors of HCV infection and their functional mechanism we analyzed the anti-HCV properties of different human derived radixin peptides. Sixteen different radixin peptides were derived, synthesized and tested. Real-time quantitative PCR, cell toxicity assay, immuno-precipitation/western blot analysis and computational resource for drug discovery software were used for experimental analysis. We found that a human radixin hinge region peptide (Peptide1) can specifically block HCV J6/JFH-1 infection of Huh7.5 cells. Peptide 1 had no cell toxicity or intracellular uptake into Huh7.5 cells. Mechanistically, the anti-HCV activity of Peptide 1 extended to disruption of HCV engagement of CD81 thereby blocking downstream SYK activation, which we have recently demonstrated to be important for effective HCV infection of target hepatocytes. Our findings highlight a novel functional class of anti-HCV agents that can inhibit HCV infection, most likely by disrupting vital viral-host signaling interactions at the level of virus entry.

Human ezrin-moesin-radixin proteins modulate hepatitis C virus infection

Host cytoskeletal proteins of the ezrin-moesin-radixin (EMR) family have been shown to modulate single-stranded RNA virus infection through regulating stable microtubule formation. Antibody engagement of CD81, a key receptor for hepatitis C virus (HCV) entry, induces ezrin phosphorylation. Here we tested the role of EMR proteins in regulating HCV infection and explored potential therapeutic targets. We show that HCV E2 protein induces rapid ezrin phosphorylation and its cellular redistribution with F-actin by way of spleen tyrosine kinase (SYK). Therapeutically blocking the functional roles of SYK or F-actin reorganization significantly reduced Huh7.5 cell susceptibility to HCV J6/JFH-1 infection. Using gene regulation, real-time quantitative polymerase chain reaction, western blot, and fluorescent microscopy analysis, we found that proteins of the EMR family differentially regulate HCV infection in the J6/JFH-1/Huh7.5 cell system. Moesin and radixin, but not ezrin, expression were significantly decreased in chronic HCV J6/JFH-1-infected Huh7.5 cells and HCV-infected patient liver biopsies compared to controls. The decreases in moesin and radixin in HCV J6/JFH-1-infected Huh7.5 cells were associated with a significant increase in stable microtubules. Ezrin knockdown inhibited immediate postentry events in HCV infection. Overexpression of moesin or radixin significantly reduced HCV protein expression. In contrast, transient knockdown of moesin or radixin augmented HCV infection. Making use of the Con1 HCV replicon system, we tested the effect of EMR proteins on HCV replication. We found that transient knockdown of moesin increased HCV RNA expression while overexpression of EMR showed no significant effect on HCV replication.

CONCLUSION

Our findings demonstrate the important role of EMR proteins during HCV infection at the postentry level and highlight possible novel targets for HCV treatment.

MicroRNAs in liver disease

Small, noncoding microRNAs (miRNAs) regulate diverse biological functions in the liver and increasing evidence suggests that they have a role in liver pathology. This Review summarizes advances in the field of miRNAs in liver diseases, inflammation and cirrhosis. MicroRNA-122, the most abundant miRNA in hepatocytes, has well-defined roles in HCV replication, and data indicate that it also serves as a viable therapeutic target. The role of miR-122 is also emerging in other liver diseases. Ample evidence exists for the important regulatory potential of other miRNAs in conditions associated with liver inflammation related to alcohol use, the metabolic syndrome or autoimmune processes. In addition, a broad array of miRNAs have been associated with the development of liver fibrosis both in animal models and human studies. The significance of the function and cellular distribution of miRNAs in the liver and the potential of miRNAs as a means of communication between cells and organs is discussed as well as the emerging utility of circulating miRNAs as biomarkers of different forms of liver damage and as early markers of disease and progression in hepatocellular carcinoma. Importantly, miRNA modulation in the liver represents a new therapeutic approach in the treatment armamentarium of hepatologists in the future.

Mechanisms of HCV-induced liver cancer: what did we learn from in vitro and animal studies?

Hepatitis C virus (HCV) is a cause of liver diseases that range from steatohepatitis, to fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). The challenge of understanding the pathogenesis of HCV-associated liver cancer is difficult as most standard animal models used in biomedical research are not permissive to HCV infection. Herein, we provide an overview of a number of creative in vivo, mostly in the mouse, and in vitro models that have been developed to advance our understanding of the molecular and cellular effects of HCV on the liver, specifically with their relevance to HCC.