Promotion of hepatocellular carcinoma by hepatitis C virus

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.

Induction of broadly neutralizing antibodies using a secreted form of the hepatitis C virus E1E2 heterodimer as a vaccine candidate

SignificanceHepatitis C virus chronically infects approximately 1% of the world's population, making an effective vaccine for hepatitis C virus a major unmet public health need. The membrane-associated E1E2 envelope glycoprotein has been used in clinical studies as a vaccine candidate. However, limited neutralization breadth and difficulty in producing large amounts of homogeneous membrane-associated E1E2 have hampered efforts to develop an E1E2-based vaccine. Our previous work described the design and biochemical validation of a native-like soluble secreted form of E1E2 (sE1E2). Here, we describe the immunogenic characterization of the sE1E2 complex. sE1E2 elicited broadly neutralizing antibodies in immunized mice, with increased neutralization breadth relative to the membrane-associated E1E2, thereby validating this platform as a promising model system for vaccine development.

The Bank Vole (Clethrionomys glareolus)—Small Animal Model for Hepacivirus Infection

Many people worldwide suffer from hepatitis C virus (HCV) infection, which is frequently persistent. The lack of efficient vaccines against HCV and the unavailability of or limited compliance with existing antiviral therapies is problematic for health care systems worldwide. Improved small animal models would support further hepacivirus research, including development of vaccines and novel antivirals. The recent discovery of several mammalian hepaciviruses may facilitate such research. In this study, we demonstrated that bank voles (Clethrionomys glareolus) were susceptible to bank vole-associated Hepacivirus F and Hepacivirus J strains, based on the detection of hepaciviral RNA in 52 of 55 experimentally inoculated voles. In contrast, interferon α/β receptor deficient C57/Bl6 mice were resistant to infection with both bank vole hepaciviruses (BvHVs). The highest viral genome loads in infected voles were detected in the liver, and viral RNA was visualized by in situ hybridization in hepatocytes, confirming a marked hepatotropism. Furthermore, liver lesions in infected voles resembled those of HCV infection in humans. In conclusion, infection with both BvHVs in their natural hosts shares striking similarities to HCV infection in humans and may represent promising small animal models for this important human disease.

From Structural Studies to HCV Vaccine Design

Hepatitis C virus (HCV) is a serious and growing public health problem despite recent developments of antiviral therapeutics. To achieve global elimination of HCV, an effective cross-genotype vaccine is needed. The failure of previous vaccination trials to elicit an effective cross-reactive immune response demands better vaccine antigens to induce a potent cross-neutralizing response to improve vaccine efficacy. HCV E1 and E2 envelope (Env) glycoproteins are the main targets for neutralizing antibodies (nAbs), which aid in HCV clearance and protection. Therefore, a molecular-level understanding of the nAb responses against HCV is imperative for the rational design of cross-genotype vaccine antigens. Here we summarize the recent advances in structural studies of HCV Env and Env-nAb complexes and how they improve our understanding of immune recognition of HCV. We review the structural data defining HCV neutralization epitopes and conformational plasticity of the Env proteins, and the knowledge applicable to rational vaccine design.

Design of a native-like secreted form of the hepatitis C virus E1E2 heterodimer

Hepatitis C virus (HCV) is a major worldwide health burden, and a preventive vaccine is needed for global control or eradication of this virus. A substantial hurdle to an effective HCV vaccine is the high variability of the virus, leading to immune escape. The E1E2 glycoprotein complex contains conserved epitopes and elicits neutralizing antibody responses, making it a primary target for HCV vaccine development. However, the E1E2 transmembrane domains that are critical for native assembly make it challenging to produce this complex in a homogenous soluble form that is reflective of its state on the viral envelope. To enable rational design of an E1E2 vaccine, as well as structural characterization efforts, we have designed a soluble, secreted form of E1E2 (sE1E2). As with soluble glycoprotein designs for other viruses, it incorporates a scaffold to enforce assembly in the absence of the transmembrane domains, along with a furin cleavage site to permit native-like heterodimerization. This sE1E2 was found to assemble into a form closer to its expected size than full-length E1E2. Preservation of native structural elements was confirmed by high-affinity binding to a panel of conformationally specific monoclonal antibodies, including two neutralizing antibodies specific to native E1E2 and to its primary receptor, CD81. Finally, sE1E2 was found to elicit robust neutralizing antibodies in vivo. This designed sE1E2 can both provide insights into the determinants of native E1E2 assembly and serve as a platform for production of E1E2 for future structural and vaccine studies, enabling rational optimization of an E1E2-based antigen.

Utilization of animal models to investigate nonalcoholic steatohepatitis-associated hepatocellular carcinoma

Nonalcoholic fatty liver disease (NAFLD) comprises a spectrum of liver disorders with fat accumulation from simple fatty liver, nonalcoholic steatohepatitis (NASH), fibrosis/cirrhosis and NAFLD/NASH-associated hepatocellular carcinoma (HCC). NASH is a progressive form of NAFLD and requires medical attention. One of 5-10 NASH patients may progress to end-state liver disease (ESLD or cirrhosis) in 5-10 years; meanwhile, life-threatening complications of ESLD and HCC account for major mortality. An increasing burden of NAFLD in clinics, elucidation of its pathogenesis and progression, and assessment of the efficacy of potential therapeutics demand reliable animal models. Most NASH-associated HCC occurs in cirrhotic subjects; however, HCC does appear in NASH patients without cirrhosis. Lipotoxicity, oxidant stress, insulin resistance, endoplasmic reticulum stress, altered adipokine and lymphokine profiles and gut microbiome changes affect NAFLD progression and constitute key pathobiologic interplays. How these factors promote malignant transformation in a microenvironment of steatotic inflammation and fibrosis/cirrhosis, and lead to development of neoplasms is one of critical questions faced in the hepatology field. The present review summarizes the characteristics of emerging rodent NASH-HCC models, and discusses the challenges in utilizing these models to unveil the mysteries of NASH-associated HCC development.

Hepatitis C Virus Indirectly Disrupts DNA Damage-Induced p53 Responses by Activating Protein Kinase R

Many DNA tumor viruses promote cellular transformation by inactivating the critically important tumor suppressor protein p53. In contrast, it is not known whether p53 function is disrupted by hepatitis C virus (HCV), a unique, oncogenic RNA virus that is the leading infectious cause of liver cancer in many regions of the world. Here we show that HCV-permissive, liver-derived HepG2 cells engineered to constitutively express microRNA-122 (HepG2/miR-122 cells) have normal p53-mediated responses to DNA damage and that HCV replication in these cells potently suppresses p53 responses to etoposide, an inducer of DNA damage, or nutlin-3, an inhibitor of p53 degradation pathways. Upregulation of p53-dependent targets is consequently repressed within HCV-infected cells, with potential consequences for cell survival. Despite this, p53 function is not disrupted by overexpression of the complete HCV polyprotein, suggesting that altered p53 function may result from the host response to viral RNA replication intermediates. Clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-mediated ablation of double-stranded RNA (dsRNA)-activated protein kinase R (PKR) restored p53 responses while boosting HCV replication, showing that p53 inhibition results directly from viral activation of PKR. The hepatocellular abundance of phosphorylated PKR is elevated in HCV-infected chimpanzees, suggesting that PKR activation and consequent p53 inhibition accompany HCV infection in vivo. These findings reveal a feature of the host response to HCV infection that may contribute to hepatocellular carcinogenesis.

Chronic infection with hepatitis C virus (HCV) is the leading cause of liver cancer in most developed nations. However, the mechanisms whereby HCV infection promotes carcinogenesis remain unclear. Here, we demonstrate that HCV infection inhibits the activation of p53 following DNA damage. Contrary to previous reports, HCV protein expression is insufficient to inhibit p53. Rather, p53 inhibition is mediated by cellular protein kinase R (PKR), which is activated by HCV RNA replication and subsequently suppresses global protein synthesis. These results redefine our understanding of how HCV infection influences p53 function. We speculate that persistent disruption of p53-mediated DNA damage responses may contribute to hepatocellular carcinogenesis in chronically infected individuals.

HCV core protein inhibits polarization and activity of both M1 and M2 macrophages through the TLR2 signaling pathway

Hepatitis C virus (HCV) establishes persistent infection in most infected patients, and eventually causes chronic hepatitis, cirrhosis, and hepatocellular carcinoma in some patients. Monocytes and macrophages provide the first line of defense against pathogens, but their roles in HCV infection remains unclear. We have reported that HCV core protein (HCVc) manipulates human blood-derived dendritic cell development. In the present study, we tested whether HCVc affects human blood-derived monocyte differentiating into macrophages. Results showed that HCVc inhibits monocyte differentiation to either M1 or M2 macrophages through TLR2, associated with impaired STATs signaling pathway. Moreover, HCVc inhibits phagocytosis activity of M1 and M2 macrophages, M1 macrophage-induced autologous and allogeneic CD4+ T cell activation, but promotes M2 macrophage-induced autologous and allogeneic CD4+ T cell activation. In conclusion, HCVc inhibits monocyte-derived macrophage polarization via TLR2 signaling, leading to dysfunctions of both M1 and M2 macrophages in chronic HCV infected patients. This may contribute to the mechanism of HCV persistent infection, and suggest that blockade of HCVc might be a novel therapeutic approach to treating HCV infection.

Hepatitis viruses exploitation of host DNA methyltransferases functions

Hepatitis B virus (HBV), hepatitis C virus (HCV) and Delta (HDV) infections are a global health burden. With different routes of infection and biology, HBV, HCV and HDV are capable to induce liver cirrhosis and cancer by impinging on epigenetic mechanisms altering host cell's pathways. In the present manuscript, we reviewed the published studies taking into account the relationship between the hepatitis viruses and the DNA methyltransferases proteins.

Role of the exogenous HCV core protein in the interaction of human hepatocyte proliferation and macrophage sub-populations

BACKGROUND

The core protein of hepatitis C virus (HCV) is found in the cytoplasm and nuclei of infected cells, including hepatocytes and other cells in the liver. The core protein could be secreted as well. Resident liver macrophages are dependent on the tissue micro-environment and external stimuli to differentiate M1 and M2 hypotypes with distinct functions, and increased expression of the nuclear transcription factor STAT3 was seen in M2-polarized macrophages. In contrast to proinflammatory M1 macrophages, M2 macrophages serve beneficial roles in chronic inflammation, immunosuppression, and tumorigenesis.

METHODS

Monocyte-derived human macrophage line (mTHP-1) was treated with the exogenous HCV core protein. Next, the mTHP-1 culture supernatant or cell pellets were added to culture media of normal human liver cell line (L02).

RESULTS

Only the culture supernatant stimulated L02 cells proliferation, which was associated with phosphorylated ERK expression. Core protein activated mTHP-1 cells showed enhanced pro- and anti-inflammatory cytokines secretion, which was accompanied by high expression of phosphorylated NF-κB105 and NF-κB65. However, phosphorylated STAT1, and STAT3, which are normally associated with M1 and M2 macrophage polarization, and cell surface expression of CD206, CD14, CD16, and CD86, were unaltered. A transwell co-culture system showed that only in mTHP-1 co-cultured with L02 in the presence of exogenous core protein, were higher levels of phosphorylated STAT3 and CD206 seen.

CONCLUSIONS

We showed L02 cells proliferation was accelerated by the culture supernatant of mTHP-1 cells treated with the exogenous HCV core protein. The exogenous core protein mediated the interaction between macrophages and hepatocytes in co-culture, which enhanced the expression of phosphorylated STAT3 and CD206 in macrophages.

Andrographolide exerts anti-hepatitis C virus activity by up-regulating haeme oxygenase-1 via the p38 MAPK/Nrf2 pathway in human hepatoma cells

BACKGROUND AND PURPOSE

This study aimed to evaluate the anti-hepatitis C virus (HCV) activity of andrographolide, a diterpenoid lactone extracted from Andrographis paniculata, and to identify the signalling pathway involved in its antiviral action.

EXPERIMENTAL APPROACH

Using HCV replicon and HCVcc infectious systems, we identified anti-HCV activity of andrographolide by measuring protein and RNA levels. A reporter activity assay was used to determine transcriptional regulation of anti-HCV agents. A specific inhibitor and short hairpin RNAs were used to investigate the mechanism responsible for the effect of andrographolide on HCV replication.

KEY RESULTS

In HCV replicon and HCVcc infectious systems, andrographolide time- and dose-dependently suppressed HCV replication. When combined with IFN-α, an inhibitor targeting HCV NS3/4A protease (telaprevir), or NS5B polymerase (PSI-7977), andrographolide exhibited a significant synergistic effect. Andrographolide up-regulated the expression of haeme oxygenase-1 (HO-1), leading to increased amounts of its metabolite biliverdin, which was found to suppress HCV replication by promoting the antiviral IFN responses and inhibiting NS3/4A protease activity. Significantly, these antiviral effects were attenuated by an HO-1-specific inhibitor or HO-1 gene knockdown, indicating that HO-1 contributed to the anti-HCV activity of andrographolide. Andrographolide activated p38 MAPK phosphorylation, which stimulated nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated HO-1 expression, and this was found to be associated with its anti-HCV activity.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that andrographolide has the potential to control HCV replication and suggest that targeting the Nrf2-HO-1 signalling pathway might be a promising strategy for drug development.

Oxidative stress and hepatic Nox proteins in chronic hepatitis C and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common liver cancer and a leading cause of cancer-related mortality in the world. Hepatitis C virus (HCV) is a major etiologic agent of HCC. A majority of HCV infections lead to chronic infection that can progress to cirrhosis and, eventually, HCC and liver failure. A common pathogenic feature present in HCV infection, and other conditions leading to HCC, is oxidative stress. HCV directly increases superoxide and H2O2 formation in hepatocytes by elevating Nox protein expression and sensitizing mitochondria to reactive oxygen species generation while decreasing glutathione. Nitric oxide synthesis and hepatic iron are also elevated. Furthermore, activation of phagocytic NADPH oxidase (Nox) 2 of host immune cells is likely to exacerbate oxidative stress in HCV-infected patients. Key mechanisms of HCC include genome instability, epigenetic regulation, inflammation with chronic tissue injury and sustained cell proliferation, and modulation of cell growth and death. Oxidative stress, or Nox proteins, plays various roles in these mechanisms. Nox proteins also function in hepatic fibrosis, which commonly precedes HCC, and Nox4 elevation by HCV is mediated by transforming growth factor β. This review summarizes mechanisms of oncogenesis by HCV, highlighting the roles of oxidative stress and hepatic Nox enzymes in HCC.

HCV core-mediated activation of latent TGF-β via thrombospondin drives the crosstalk between hepatocytes and stromal environment

BACKGROUND & AIMS

The mechanisms by which fibrosis, cirrhosis, and hepatocellular carcinoma (HCC) develop during chronic hepatitis C virus (HCV) infection are not fully understood. We previously observed that HCV core protein induced a TGF-β-dependent epithelial mesenchymal transition, a process contributing to the promotion of cell invasion and metastasis by impacting TGF-β1 signalling. Here we investigated HCV core capacity to drive increased expression of the active form of TGF-β1n transgenic mice and hepatoma cell lines.

METHODS

We used an in vivo model of HCV core expressing transgenic mice.

RESULTS

We observed that about 50% of genes deregulated by core protein expression were TGF-β1 target genes. Active TGF-β levels were increased in HCV core transgenic mouse livers. Overexpression of core protein in hepatoma cells increased active TGF-β levels in culture supernatants and induced Smad2/3 phosphorylation, thus reflecting activation of the TGF-β signaling pathway. Moreover, our data showed the implication of thrombospondin-1 in core-dependent TGF-β activation. Finally, hepatoma cells expressing HCV core could activate stellate cells in co-culture and this activation was TGF-β dependent.

CONCLUSIONS

Collectively, these data delineate a novel paradigm where HCV may be related to liver pathogenesis through its ability to induce a local, intrahepatic TGF-β activation. They argue for a dual impact of HCV core on liver fibrosis and liver carcinogenesis: HCV core could act both as autocrine and paracrine factor modulating TGF-β responses within hepatocytes and in stromal environment through TGF-β activation.

Increased international normalized ratio level in hepatocellular carcinoma patients with diabetes mellitus

AIM: To determine the association of diabetes mellitus (DM) and international normalized ratio (INR) level in hepatocellular carcinoma (HCC) patients.

METHODS: Our present study included 375 HCC patients who were treated at the China-Japan Friendship Hospital, Ministry of Health (Beijing, China), in the period from January 2003 to April 2012, and with a hospital discharge diagnosis of HCC. The demographic, clinical, laboratory, metabolic and instrumental features were analyzed. χ² test, Student’s t test and Mann-Whitney U test were used to compare the differences between HCC patients with and without DM. Unconditional multivariable logistic regression analysis was used to determine the association of DM and INR level in HCC patients. A sub-group analysis was performed to assess the effect of liver cirrhosis or hepatitis B virus (HBV) infection on the results. The Pearson correlation test was used to determine the relationship between INR level and fasting glucose. In addition, association between diabetes duration, and diabetes treatment and INR level was determined considering the potentially different effects.

RESULTS: Of the total, 63 (16.8%) patients were diabetic (diabetic group) and 312 (83.2%) patients were diagnosed without diabetes (non-diabetic group). Their mean age was 56.4 ± 11.0 years and 312 (83.2%) patients were male. Compared with patients without DM, the HCC patients with diabetes were older (59.5 ± 10.3 vs 55.8 ± 11.1, P = 0.015), had a lower incidence of HBV infection (79.4% vs 89.1%, P = 0.033), had increased levels of systolic blood pressure (SBP) (133 ± 17 vs 129 ± 16 mmHg, P = 0.048) and INR (1.31 ± 0.44 vs 1.18 ± 0.21, P = 0.001), had lower values of hemoglobin (124.4 ± 23.9 vs 134.2 ± 23.4, P = 0.003) and had a platelet count (median/interquartile-range: 113/64-157 vs 139/89-192, P = 0.020). There was no statistically significant difference in the percentages of males, overweight or obesity, drinking, smoking, cirrhosis and Child classification. After controlling for the confounding effects of age, systolic blood pressure, hemoglobin, platelet count and HBV infection by logistic analyses, INR was shown as an independent variable [odds ratio (OR) = 3.650; 95%CI: 1.372-9.714, P = 0.010]. Considering the effect of liver cirrhosis on results, a sub-group analysis was performed and the study population was restricted to those patients with cirrhosis. Univariate analysis showed that diabetic patients had a higher INR than non-diabetic patients (1.43 ± 0.51 vs 1.25 ± 0.23, P = 0.041). After controlling for confounding effect of age, SBP, hemoglobin, platelet count and HBV infection by logistic analyses, INR level remained as the sole independent variable (OR = 5.161; 95%CI: 1.618-16.455, P = 0.006). No significant difference in the relationship between INR level and fasting glucose was shown by Pearson test (r = 0.070, P = 0.184). Among the 63 diabetic patients, 35 (55.6%) patients had been diagnosed with DM for more than 5 years, 23 (36.5%) received oral anti-diabetic regimens, 11 (17.5%) received insulin, and 30 (47.6%) reported relying on diet alone to control serum glucose levels. No significant differences were found for the association between DM duration/treatment and INR level, except for the age at diabetes diagnosis.

CONCLUSION: The INR level was increased in HCC patients with DM and these patients should be monitored for the coagulation function in clinical practice.

DExD/H-box RNA helicases as mediators of anti-viral innate immunity and essential host factors for viral replication

Traditional functions of DExD/H-box helicases are concerned with RNA metabolism; they have been shown to play a part in nearly every cellular process that involves RNA. On the other hand, it is accepted that DexD/H-box helicases also engage in activities that do not require helicase activity. A number of DExD/H-box helicases have been shown to be involved in anti-viral immunity. The RIG-like helicases, RIG-I, mda5 and lgp2, act as important cytosolic pattern recognition receptors for viral RNA. Detection of viral nucleic acids by the RIG-like helicases or other anti-viral pattern recognition receptors leads to the induction of type I interferons and pro-inflammatory cytokines. More recently, additional DExD/H-box helicases have also been implicated to act as cytosolic sensors of viral nucleic acids, including DDX3, DDX41, DHX9, DDX60, DDX1 and DHX36. However, there is evidence that at least some of these helicases might have more downstream functions in pattern recognition receptor signalling pathways, as signalling adaptors or transcriptional regulators. In an interesting twist, a lot of DExD/H-box helicases have also been identified as essential host factors for the replication of different viruses, suggesting that viruses 'hijack' their RNA helicase activities for their benefit. Interestingly, DDX3, DDX1 and DHX9 are among the helicases that are required for the replication of a diverse range of viruses. This might suggest that these helicases are highly contested targets in the ongoing 'arms race' between viruses and the host immune system. This article is part of a Special Issue entitled: The Biology of RNA helicases - Modulation for life.

Predictors of Developing Hepatocellular Carcinoma in Treated HCV-Carriers in Morocco according to University Hospital Experience

Introduction. Hepatitis C is the first major cause for HCC in Morocco. Antiviral treatment reduces the risk of developing HCC but few cases of HCC in HCV-treated patients were reported. We aimed to define this population's features and to identify predictive factors of developing HCC. Patients and Methods. We included all HCV carriers who developed HCC after antiviral treatment from January 2002 to April 2010. We compare HCV-treated patients with no developed HCC to HCC population using khi-2 and Fisher Exact analysis. Results. 369 HVC-treated patients were considered, and 20 HCC were reported. The risk of HCC was not significant according to gender and genotypes (resp., P = 0.63 and P = 0.87). Advanced age and severe fibrosis were significant risk factors (resp., P = 0.003 and P = 0.0001). HCC was reported in 2.6% of sustained virological responders versus 12.5% of nonresponders (P = 0.004). Conclusion. In our series, 5% of previously treated patients developed an HCC. Advanced age and severe fibrosis at HCV diagnosis are predictive factors of HCC occurrence. Sustained virological response reduces considerably the risk of HCC occurrence but screening is indicated even after SVR.