Hepatitis C virus core protein binds to the cytoplasmic domain of tumor necrosis factor (TNF) receptor 1 and enhances TNF-induced apoptosis

Hepatitis C Core Protein Induces a Genotype-Specific Susceptibility of Hepatocytes to TNF-Induced Death In Vitro and In Vivo

Hepatitis C virus (HCV) core protein is a multifunctional protein that is involved in the proliferation, inflammation, and apoptosis mechanism of hepatocytes. HCV core protein genetic variability has been implicated in various outcomes of HCV pathology and treatment. In the present study, we aimed to analyze the role of the HCV core protein in tumor necrosis factor α (TNFα)-induced death under the viewpoint of HCV genetic variability. Immortalized hepatocytes (IHH), and not the Huh 7.5 hepatoma cell line, stably expressing HCV subtype 4a and HCV subtype 4f core proteins showed that only the HCV 4a core protein could increase sensitivity to TNFα-induced death. Development of two transgenic mice expressing the two different core proteins under the liver-specific promoter of transthyretin (TTR) allowed for the in vivo assessment of the role of the core in TNFα-induced death. Using the TNFα-dependent model of lipopolysaccharide/D-galactosamine (LPS/Dgal), we were able to recapitulate the in vitro results in IHH cells in vivo. Transgenic mice expressing the HCV 4a core protein were more susceptible to the LPS/Dgal model, while mice expressing the HCV 4f core protein had the same susceptibility as their littermate controls. Transcriptome analysis in liver biopsies from these transgenic mice gave insights into HCV core molecular pathogenesis while linking HCV core protein genetic variability to differential pathology in vivo.

Effects of alcohol consumption on viral hepatitis B and C

The liver is the main target organ for hepatitis viruses and the vital organ for alcohol metabolism. These two factors of viral hepatitis and alcohol abuse in combination can exert dual harmful actions, leading to enhanced damage to the liver. Epidemiological studies have revealed a higher prevalence of hepatitis C virus (HCV) infection among alcoholics than the general population. The interaction of alcohol with viral hepatitis [e.g., hepatitis B virus (HBV), HCV] and the underlying mechanisms are not fully understood. The effects of alcohol on viral hepatitis include promoted viral replication, weakened immune response, and increased oxidative stress. Clinically, alcohol abuse is correlated with an increased risk of developing end-stage liver cirrhosis and hepatocellular carcinoma in patients with chronic hepatitis B and C, suggesting that the combination of alcohol and HBV/HCV lead to more severe liver damage. The influence of mild to moderate alcohol drinking on the HBV-induced liver fibrosis, cirrhosis, and hepatocellular carcinoma among patients infected with HBV remains unclear. Unlike HBV infected patients, no safe level of alcohol intake has been established for patients with HCV. Even light to moderate alcohol use can exert a synergistic effect with viral hepatitis, leading to the rapid progression of liver disease. Furthermore, interferon-based therapy is less effective in alcohol drinkers than in control patients, even after abstinence from alcohol for a period of time. Therefore, abstaining from alcohol is highly recommended to protect the liver, especially in individuals with HBV/HCV infection, to improve the clinical efficacy of antiviral treatment and prevent the rapid progression of chronic viral hepatitis.

Molecular pathways in viral hepatitis-associated liver carcinogenesis: An update

Hepatocellular carcinoma (HCC) is the most common type of cancer among primary malignant tumors of the liver and is a consequential cause of cancer-related deaths worldwide. In recent years, uncovering the molecular mechanisms involved in the development and behavior of this tumor has led to the identification of multiple potential treatment targets. Despite the vast amount of data on this topic, HCC remains a challenging tumor to treat due to its aggressive behavior and complex molecular profile. Therefore, the number of studies aiming to elucidate the mechanisms involved in both carcinogenesis and tumor progression in HCC continues to increase. In this context, the close association of HCC with viral hepatitis has led to numerous studies focusing on the direct or indirect involvement of viruses in the mechanisms contributing to tumor development and behavior. In line with these efforts, this review was undertaken to highlight the current understanding of the molecular mechanisms by which hepatitis B virus (HBV) and hepatitis C virus (HCV) participate in oncogenesis and tumor progression in HCC and summarize new findings. Cumulative evidence indicates that HBV DNA integration promotes genomic instability, resulting in the overexpression of genes related to cancer development, metastasis, and angiogenesis or inactivation of tumor suppressor genes. In addition, genetic variations in HBV itself, especially preS2 deletions, may play a role in malignant transformation. Epigenetic dysregulation caused by both viruses might also contribute to tumor formation and metastasis by modifying the methylation of DNA and histones or altering the expression of microRNAs. Similarly, viral proteins of both HBV and HCV can affect pathways that are important anticancer targets. The effects of these two viruses on the Hippo-Yap-Taz pathway in HCC development and behavior need to be investigated. Additional, comprehensive studies are also needed to determine these viruses' interaction with integrins, farnesoid X, and the apelin system in malignant transformation and tumor progression. Although the relationship of persistent inflammation caused by HBV and HCV hepatitis with carcinogenesis is well defined, further studies are warranted to decipher the relationship among inflammasomes and viruses in carcinogenesis and elucidate the role of virus-microbiota interactions in HCC development and progression.

Cellular Mechanisms of Liver Fibrosis

The liver is a central organ in the human body, coordinating several key metabolic roles. The structure of the liver which consists of the distinctive arrangement of hepatocytes, hepatic sinusoids, the hepatic artery, portal vein and the central vein, is critical for its function. Due to its unique position in the human body, the liver interacts with components of circulation targeted for the rest of the body and in the process, it is exposed to a vast array of external agents such as dietary metabolites and compounds absorbed through the intestine, including alcohol and drugs, as well as pathogens. Some of these agents may result in injury to the cellular components of liver leading to the activation of the natural wound healing response of the body or fibrogenesis. Long-term injury to liver cells and consistent activation of the fibrogenic response can lead to liver fibrosis such as that seen in chronic alcoholics or clinically obese individuals. Unidentified fibrosis can evolve into more severe consequences over a period of time such as cirrhosis and hepatocellular carcinoma. It is well recognized now that in addition to external agents, genetic predisposition also plays a role in the development of liver fibrosis. An improved understanding of the cellular pathways of fibrosis can illuminate our understanding of this process, and uncover potential therapeutic targets. Here we summarized recent aspects in the understanding of relevant pathways, cellular and molecular drivers of hepatic fibrosis and discuss how this knowledge impact the therapy of respective disease.

Long Noncoding RNA EGOT Responds to Stress Signals to Regulate Cell Inflammation and Growth

The cell has several mechanisms to sense and neutralize stress. Stress-related stimuli activate pathways that counteract danger, support cell survival, and activate the inflammatory response. We use human cells to show that these processes are modulated by EGOT, a long noncoding RNA highly induced by viral infection, whose inhibition results in increased levels of antiviral IFN-stimulated genes (ISGs) and decreased viral replication. We now show that EGOT is induced in response to cell stress, viral replication, or the presence of pathogen-associated molecular patterns via the PI3K/AKT, MAPKs, and NF-κB pathways, which lead to cell survival and inflammation. Transcriptome analysis and validation experiments show that EGOT modulates PI3K/AKT and NF-κB responses. On the one hand, EGOT inhibition decreases expression of PI3K/AKT-induced cellular receptors and cell proliferation. In fact, EGOT levels are increased in several tumors. On the other hand, EGOT inhibition results in decreased levels of key NF-κB target genes, including those required for inflammation and ISGs in those cells that build an antiviral response. Mechanistically, EGOT depletion decreases the levels of the key coactivator TBLR1, essential for transcription by NF-κB. In summary, EGOT is induced in response to stress and may function as a switch that represses ISG transcription until a proper antiviral or stress response is initiated. EGOT then helps PI3K/AKT, MAPKs, and NF-κB pathways to activate the antiviral response, cell inflammation, and growth. We believe that modulation of EGOT levels could be used as a therapy for the treatment of certain viral infections, immune diseases, and cancer.

Coxsackievirus A6 Induces Necroptosis for Viral Production

Hand, foot, and mouth disease (HFMD) is a febrile exanthematous disease with typical or atypical symptoms. Typical HFMD is usually caused by enterovirus 71 (EV71) or coxsackievirus A16, while atypical HFMD is usually caused by coxsackievirus A6 (CA6). In recent years, worldwide outbreaks of CA6-associated HFMD have dramatically increased, although the pathogenic mechanism of CA6 is still unclear. EV71 has been established to induce caspase-dependent apoptosis, but in this study, we demonstrate that CA6 infection promotes a distinct pathway of cell death that involves loss of cell membrane integrity. Necrostatin-1, an inhibitor of necroptosis, blocks the cell death induced by CA6 infection, but Z-DEVD-FMK, an inhibitor of caspase-3, has no effect on CA6-induced cell death. Furthermore, CA6 infection up-regulates the expression of the necroptosis signaling molecule RIPK3. Importantly, necrostatin-1 inhibits CA6 viral production, as assessed by its ability to inhibit levels of VP1 protein and genomic RNA and infectious particles. CA6-induced necroptosis is not dependent on the generation of reactive oxygen species; however, viral 3D protein can directly bind RIPK3, which is suggestive of a direct mechanism of necroptosis induction. Therefore, these results indicate that CA6 induces a mechanism of RIPK3-dependent necroptosis for viral production that is distinct from the mechanism of apoptosis induced by typical HFMD viruses.

Complexity on modulation of NF-κB pathways by hepatitis B and C: A double-edged sword in hepatocarcinogenesis

Nuclear factor-κB (NF-κB), a family of master regulated dimeric transcription factors, signaling transduction pathways are active players in the cell signaling that control vital cellular processes, including cell growth, proliferation, differentiation, apoptosis, morphogenesis, angiogenesis, and immune responses. Nevertheless, aberrant regulation of the NF-κB signaling pathways has been associated with a significant number of human cancers. In fact, NF-κB acts as a double-edged sword in the vital cellular processes and carcinogenesis. This review provides an overview on the modulation of the NF-κB signaling pathways by proteins of hepatitis B and C viruses. One of the major NF-κB events that are modulated by these viruses is the induction of hepatocellular carcinoma. Given the central function of NF-κB in carcinogenesis, it has turned out to be a considerable therapeutic target for cancer therapy.

NF-κB signaling and crosstalk during carcinogenesis

Transcription factors (TFs) are proteins that control the transcription of genetic information from DNA to mRNA by binding to specific DNA sequences either on their own or with other proteins as a complex. TFs thus support or suppress the recruitment of the corresponding RNA polymerase. In general, TFs are classified by structure or function. The TF, Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), is expressed in all cell types and tissues. NF-κB signaling and crosstalk are involved in several steps of carcinogenesis including in sequences involving pathogenic stimulus, chronic inflammation, fibrosis, establishment of its remodeling to the precancerous niche (PCN) and transition of a normal cell to a cancer cell. Triggered by various inflammatory cytokines, NF-κB is activated along with other TFs with subsequent stimulation of cell proliferation and inhibition of apoptosis. The involvement of NF-κB in carcinogenesis provides an opportunity to develop anti-NF-κB therapies. The complexity of these interactions requires that we elucidate those aspects of NF-κB interactions that play a role in carcinogenesis, the sequence of events leading to cancer.

Heterogeneity and coexistence of oncogenic mechanisms involved in HCV-associated B-cell lymphomas

The association of HCV-infection with B-lymphomas is supported by the regression of most indolent/low-grade lymphomas following anti-viral therapy. Studies on direct and indirect oncogenic mechanisms have elucidated the pathogenesis of HCV-associated B-lymphoma subtypes. These include B-lymphocyte proliferation and sustained clonal expansion by HCV-envelope protein stimulation of B-cell receptors, and prolonged HCV-infected B-cell growth by overexpression of an anti-apoptotic BCL-2 oncogene caused by the increased frequency of t(14;18) chromosomal translocations in follicular lymphomas. HCV has been implicated in lymphomagenesis by a "hit-and-run" mechanism, inducing enhanced mutation rate in immunoglobulins and anti-oncogenes favoring immune escape, due to permanent genetic damage by double-strand DNA-breaks. More direct oncogenic mechanisms have been identified in cytokines and chemokines in relation to NS3 and Core expression, particularly in diffuse large B-cell lymphoma. By reviewing genetic alterations and disrupted signaling pathways, we intend to highlight how mutually non-contrasting mechanisms cooperate with environmental factors toward progression of HCV-lymphoma.

Retrospective Study of Patients on Etanercept Therapy for Rheumatic Diseases in Patients With Chronic Hepatitis C Virus

OBJECTIVE

Treatment of rheumatic diseases with concurrent hepatitis C virus (HCV) infection is a therapeutic challenge. Etanercept has no known hepatotoxicity; however there is a concern for worsening of HCV infection-related liver disease due to immunosuppressive action of the drug. Here, we retrospectively assessed the safety of etanercept in rheumatologic disease in patients with chronic HCV.

METHODS

A retrospective review was conducted in patients with chronic HCV infection who received etanercept for diagnosis of rheumatoid arthritis and psoriatic arthritis. The primary end point was a serum transaminase level of at least 3 times the upper limit of normal during etanercept therapy. We also recorded HCV RNA load.

RESULTS

Fourteen patients met the inclusion criteria. Mean age was 52 (SD, 8) years. The median follow-up period after initiation of etanercept was 105 months (range, 13-132 months). During follow-up, 7 of 14 patients had elevation of aspartate aminotransferase and/or alanine aminotransferase 3 times the upper limit of normal. Two of 7 patients had concomitant elevation in transaminases and increase in HCV viral load during etanercept exposure, which could not be attributed to other hepatotoxic disease-modifying antirheumatic drugs. In both patients, transaminase levels normalized upon etanercept discontinuation.

CONCLUSIONS

In contrast to the majority of previous shorter-duration studies, 2 of 14 patients in our series had possible HCV-related worsening of liver disease while on etanercept therapy. Although no firm conclusion can be drawn, it appears that HCV infection can worsen while on etanercept therapy, and therefore, we propose these patients should be monitored serially.

Virus Infection and Death Receptor-Mediated Apoptosis

Virus infection can trigger extrinsic apoptosis. Cell-surface death receptors of the tumor necrosis factor family mediate this process. They either assist persistent viral infection or elicit the elimination of infected cells by the host. Death receptor-mediated apoptosis plays an important role in viral pathogenesis and the host antiviral response. Many viruses have acquired the capability to subvert death receptor-mediated apoptosis and evade the host immune response, mainly by virally encoded gene products that suppress death receptor-mediated apoptosis. In this review, we summarize the current information on virus infection and death receptor-mediated apoptosis, particularly focusing on the viral proteins that modulate death receptor-mediated apoptosis.

Association between Hepatitis C Virus Infection, p53 Phenotypes, and Gene Variants of Adenomatous Polyposis Coli in Hepatocellular Carcinomas

OBJECTIVE

To investigate the clinical value of p53 codon 72 single nucleotide polymorphisms (SNPs) and variants of adenomatous polyposis coli (APC) in hepatocellular carcinomas (HCCs).

METHODS

DNA and RNA from 51 HCCs and their matching, uninvolved liver tissues were analyzed for p53 mutations, and the methylation and expression of APC variants were determined. Proliferation of each HCC was assessed by Ki67 immunohistochemistry. The results were correlated with the demographic and clinicopathologic features and patient survival.

RESULTS

Of 51 HCCs, 12% exhibited missense p53 mutations. SNP analysis of p53 codon 72 demonstrated the highest prevalence of the Arg/Arg (56%) phenotype, followed by Arg/Pro (33%) and Pro/Pro (11%). Four of five cases with the Pro/Pro phenotype were African Americans (AAs). All five cases with the Pro/Pro phenotype had hepatitis C virus (HCV) infections, a high Ki67 index, and lower median survival (15.5 months) compared to those with Arg/Arg or Arg/Pro phenotypes (32 months). The overall frequency of APC methylation was 31%, which was found predominantly in Caucasians. There was lower mRNA expression of APC variants-2 and -3 in both HCCs and corresponding adjacent, uninvolved liver tissues as compared to APC variant-1. The expression of APC variant-3, but not variants-1 and -2, was lower in HCCs relative to uninvolved tissues. Expression of all APC variants was lower in HCCs with APC methylation relative to HCCs without APC methylation, and low expression of APC variant-2 was associated with the Pro/Pro phenotype.

CONCLUSIONS

These findings suggest that, for AA patients with HCCs, the p53 Pro/Pro phenotype and low expression of APC variant-2 are associated with aggressive tumor behavior, HCV infection, and poor clinical outcome.

Cardioprotective effects of monocyte locomotion inhibitory factor on myocardial ischemic injury by targeting vimentin

Monocyte locomotion inhibitory factor (MLIF), a heat-stable pentapeptide produced by Entamoeba histolytica, has anti-inflammatory function and protective effect on ischemic stroke. In this study, we evaluated the effect of MLIF on myocardial ischemia. Mice were subjected to ischemia/reperfusion by occlusion of the left anterior descending artery (LAD). After sacrifice, the serum concentrations of cardiac troponin I (cTnI), creatine kinase (CK), lactate dehydrogenase (LDH) as well as the heart infarct size were measured. HE and TUNEL staining were used to observe the pathological damage and the apoptotic cells. For in vitro study, the oxygen-glucose deprivation(OGD) model was established in H9c2 cells. MTT assay and flow cytometry assay were performed to evaluate cell viability and apoptosis. The expression of JNK and caspase 3 was assessed by western blot analysis. Pull-down assay was used to detect the specific binding protein of MLIF in myocardial cells. MLIF significantly reduced the infarct size, and the cTnI, CK and LDH levels, amelioratived pathological damage and reduced the apopotosis compared with the myocardial I/R model group. MLIF improved cell survival and inhibited apoptosis and necrosis by inhibiting the p-JNK and cleaved caspase3 expression. Furthermore, the binding protein of MLIF in myocardial cells was vimentin. Inhibition of vimentin expression by withaferin A or vimentin siRNA repressed the protective effects of MLIF in OGD-provoked H9c2 cells. Taken together, our results demonstrate that the cardioprotective effects of MLIF on myocardial ischemia injury are related to reductions in the inflammatory response and apoptosis by targeting vimentin.

Hepatitis C Virus Infection Is Associated With an Increased Risk of Active Tuberculosis Disease: A Nationwide Population-Based Study

Tuberculosis (TB) and hepatitis C virus (HCV) infection contribute to major disease mortality and morbidity worldwide. However, the causal link between HCV infection and TB risk remains unclear. We conducted a population-based cohort study to elucidate the association between HCV infection and TB disease by analyzing Taiwan National Health Insurance Database. We enrolled 5454 persons with HCV infection and 54,274 age- and sex-matched non-HCV-infected persons between January 1998 and December 2007. Time-dependent Cox proportional hazards regression analysis was used to measure the association between HCV infection and active TB disease. Incidence rate of active TB disease was higher among HCV infection than in control (134.1 vs 89.1 per 100,000 person-years; incidence rate ratio 1.51; P = 0.014). HCV infection was significantly associated with active TB disease in multivariate Cox regression (adjusted hazard ratio [HR] 3.20; 95% confidence interval [CI], 1.85-5.53; P < 0.001) and competing death risk event analysis (adjusted HR 2.11; 95% CI, 1.39-3.20; P < 0.001). Multivariate stratified analysis further revealed that HCV infection was a risk of active TB disease in most strata. This nationwide cohort study suggests that HCV infection is associated with a higher risk of developing active TB disease.

The role of IL-28, IFN-γ, and TNF-α in predicting response to pegylated interferon/ribavirin in chronic HCV patients

The primary goal of HCV therapy is to achieve a sustained virological response (SVR). Many host and viral factors influence the treatment response. Cytokines play an important role in the defense against viral infections, where successful treatment of hepatitis C depends on a complex balance between pro- and anti-inflammatory responses. In the present study, we investigated the relationship between the presence and percentage of some cytokines (IL-28, IFN-γ, and TNF-α) regarding different clinicopathological parameters including response to therapy in chronic HCV patients using immunohistochemical technique. This study was carried out on 64 chronic HCV patients (34 responders and 30 non-responders). Of cases, 54% showed IL-28 expression, which was associated with low AST (p = 0.002) and low HAI score (p = 0.006). Of cases, 67 and 45% showed IFN-γ and TNF-α expression, respectively, where the median percentage of TNF-α expression was higher in grade II spotty necrosis compared to grade I. Some inflammatory cytokines expressed by intrahepatic inflammatory cells in chronic HCV patients promote inflammation and injury (pro-inflammatory) such as TNF-α. Other cytokines aid in resolving inflammation and injury (anti-inflammatory) such as IL-28. The balance between these cytokines will determine the degree of inflammatory state. None of the investigated cytokines proved its clear cut role in affecting response to therapy, however, their levels varied between responders and non-responders for further investigations to clarify.

Crimean-Congo haemorrhagic fever replication interplays with regulation mechanisms of apoptosis

Pathogenesis of viral haemorrhagic fevers is associated with alteration of vascular barrier function and haemorrhage. To date, the specific mechanism behind this is unknown. Programmed cell death and regulation of apoptosis in response to viral infection is an important factor for host or virus survival but this has not been well-studied in the case of Crimean-Congo hemorrhagic fever virus (CCHFV). In this study, we demonstrated that CCHFV infection suppresses cleavage of poly(ADP-ribose) polymerase (PARP), triggered by staurosporine early post-infection. We also demonstrated that CCHFV infection suppresses activation of caspase-3 and caspase-9. Most interestingly, we found that CCHFV N can suppress induction of apoptosis by Bax and inhibit the release of cytochrome c from the inner membrane of mitochondria to cytosol. However, CCHFV infection induces activation of Bid late post-infection, suggesting activation of extrinsic apoptotic signalling. Consistently, supernatant from cells stimulated late post-infection was found to induce PARP cleavage, most probably through the TNF-α death receptor pathway. In summary, we found that CCHFV has strategies to interplay with apoptosis pathways and thereby regulate caspase cascades. We suggest that CCHFV suppresses caspase activation at early stages of the CCHFV replication cycle, which perhaps benefits the establishment of infection. Furthermore, we suggest that the host cellular response at late stages post-infection induces host cellular pro-apoptotic molecules through the death receptor pathway.

Hepatitis C virus infection increases risk of developing end-stage renal disease using competing risk analysis

Background

Chronic kidney disease (CKD) and hepatitis C virus (HCV) infection are closely linked and both increase patient mortality. The association of HCV and risk of developing end-stage renal disease (ESRD) has not been analyzed with competing risk model.

Method

We enrolled a prospective cohort of 4,185 patients (mean age, 62 years; 41% female) registered in the CKD integrated care program at two affiliated hospitals of Kaohsiung Medical University in Taiwan between November 11, 2002 and May 31, 2009. With competing risk model, we analyzed the association of HCV infection, defined by seropositive of anti-HCV antibody, and hepatitis B virus (HBV) infection, defined by seropositive of HBV surface antigen, with the risk of entering ESRD.

Results

The prevalence of HCV infection was 7.6% and it increased with the CKD stages (trend test, P<0.001), while the prevalence of HBV infection was 7.4% and no specific trend among CKD stages (tend test, P = 0.1). During the 9,101 person-year follow-up period, there were 446 death and 1,205 patients entering ESRD. After adjusting death as the competing risk, the estimated 5-year cumulative incidence rate of ESRD among patients with and without HCV infection were 52.6% and 38.4%, respectively (modified log-rank, P<0.001). Multivariable analysis showed that HCV infection, but not HBV infection, had higher risk of developing ESRD compared with cases without infection (HCV, HR: 1.32, 95% CI: 1.07–1.62; HBV, HR: 1.10, 95% CI: 0.89–1.35). Subgroup analyses showed consistent results.

Conclusions

With death-adjusted competing risk analysis, HCV infection is associated with an increased risk of developing ESRD in CKD cohort.

Regulation and dysregulation of tumor necrosis factor receptor-1

TNF is an essential regulator of the immune system. Dysregulation of TNF plays a role in the pathology of many auto-immune diseases. TNF-blocking agents have proven successful in the treatment of such diseases. Development of novel, safer or more effective drugs requires a deeper understanding of the regulation of the pro-inflammatory activities of TNF and its receptors. The ubiquitously expressed TNFR1 is responsible for most TNF effects, while TNFR2 has a limited expression pattern and performs immune-regulatory functions. Despite extensive knowledge of TNFR1 signaling, the regulation of TNFR1 expression, its modifications, localization and processing are less clear and the data are scattered. Here we review the current knowledge of TNFR1 regulation and discuss the impact this has on the host.

Alternate reading frame protein (F protein) of hepatitis C virus: paradoxical effects of activation and apoptosis on human dendritic cells lead to stimulation of T cells

Hepatitis C virus (HCV) leads to chronic infection in the majority of infected individuals due to lack, failure, or inefficiency of generated adaptive immune responses. In a minority of patients, acute infection is followed by viral clearance. The immune correlates of viral clearance are not clear yet but have been extensively investigated, suggesting that multispecific and multifunctional cellular immunity is involved. The generation of cellular immunity is highly dependent upon how antigen presenting cells (APCs) process and present various viral antigens. Various structural and non-structural HCV proteins derived from the open reading frame (ORF) have been implicated in modulation of dendritic cells (DCs) and APCs. Besides the major ORF proteins, the HCV core region also encodes an alternate reading frame protein (ARFP or F), whose function in viral pathogenesis is not clear. In the current studies, we sought to determine the role of HCV-derived ARFP in modulating dendritic cells and stimulation of T cell responses. Recombinant adenovirus vectors containing F or core protein derived from HCV (genotype 1a) were prepared and used to endogenously express these proteins in dendritic cells. We made an intriguing observation that endogenous expression of F protein in human DCs leads to contrasting effects on activation and apoptosis of DCs, allowing activated DCs to efficiently internalize apoptotic DCs. These in turn result in efficient ability of DCs to process and present antigen and to prime and stimulate F protein derived peptide-specific T cells from HCV-naive individuals. Taken together, our findings suggest important aspects of F protein in modulating DC function and stimulating T cell responses in humans.

Myocardial performance in children with autoimmune hepatitis: Doppler tissue imaging study

Autoimmune hepatitis (AIH) is a member of autoimmune diseases family which can increase risk of cardiovascular morbidity and mortality. This study aimed to assess subclinical impact of AIH on global myocardial performance in affected children using Doppler tissue imaging (DTI) and to correlate it with total serum immunoglobulin-G (IgG). Thirty children with AIH (mean age = 12.67 ± 2.9 years) was included as the study group and 20 age- and sex-matched healthy children (mean age = 11.93 ± 2.66 years) as the control group. Conventional two-dimensional echocardiography was performed to both groups and DTI were used to determine right ventricular (RV) and left ventricular (LV) Tei indexes. Total serum IgG levels at initial diagnosis of AIH were correlated to the cardiac functions of AIH patients. RV and LV Tei indexes were significantly higher in AIH group (mean ± SD: 0.46 ± 0.088 vs. 0.26 ± 0.01, P < 0.0001 and 0.45 ± 0.086 vs. 0.31 ± 0.02, P < 0.0001, respectively). Also, total IgG concentrations were correlated positively with the LV Tei index (r = 0.69, P < 0.0001) and with the RV Tei index (r = 0.61, P < 0.0003) and correlated negatively with the mitral systolic (Sm) velocity (r = -0.76, P < 0.0001) and with tricuspid systolic (Sm) velocity (r = -0.66, P < 0.0001). On the other hand, fractional shortening did not correlate with serum IgG concentrations (r = -0.04, P = 0.821). In conclusion, the DTI technique appears to be more sensitive than conventional echocardiography in the early detection of myocardial dysfunction in AIH children.

Tumour necrosis factor in infectious disease

TNF signals through two distinct receptors, designated TNFR1 and TNFR2, which initiate diverse cellular effects that include cell survival, activation, differentiation, and proliferation and cell death. These cellular responses can promote immunological and inflammatory responses that eradicate infectious agents, but can also lead to local tissue injury at sites of infection and harmful systemic effects. Defining the molecular mechanisms involved in TNF responses, the effects of natural and experimental genetic diversity in TNF signalling and the effects of therapeutic blockade of TNF has increased our understanding of the key role that TNF plays in infectious disease.

RNA virus capsid proteins: more than just a shell

Capsid proteins are obligatory components of infectious virions. Their primary structural function is to protect viral genomes during entry and exit from host cells. Evidence suggests that these proteins can also modulate the activity and specificity of viral replication complexes. More recently, it has become apparent that they play critical roles at the virus–host interface. Here, we discuss how capsid proteins of RNA viruses interact with key host cell proteins and pathways to modulate cell physiology in order to benefit virus replication. Capsid–host cell interactions may also have implications for viral disease. Understanding how capsids regulate virus–host interactions may lead to the development of novel antiviral therapies based on targeting the activities of cellular proteins.

Tumor-initiating stem-like cells and drug resistance: carcinogenesis through Toll-like receptors, environmental factors, and virus

Neoplasms contain distinct subpopulations of cells known as tumor-initiating stem-like cells (TICs) that have been identified as key drivers of tumor growth and malignant progression with drug resistance. Stem cells normally proliferate through self-renewing divisions in which the two daughter cells differ markedly in their proliferative potential, with one displaying the differentiation phenotypes and another retaining self-renewing activity. Therefore, understanding the molecular mechanisms of hepatocarcinogenesis will be required for the eventual development of improved therapeutic modalities for treating hepatocellular carcinoma (HCC). Hepatitis C virus (HCV) and hepatitis B virus is a major cause of HCC. Compelling epidemiologic evidence identifies obesity and alcohol as co-morbidity factors that can increase the risk of HCV patients for HCC, especially in alcoholics or obese patients. The mechanisms underlying liver oncogenesis, and how environmental factors contribute to this process, are not yet understood. The HCV-Toll-like receptor 4 (TLR4)-Nanog signaling network is established since alcohol/obesity-associated endotoxemia then activates TLR4 signaling, resulting in the induction of the stem cell marker Nanog expression and liver tumors. Liver TICs are highly sensitized to leptin and exposure of TICs to leptin increases the expression and activity of an intrinsic pluripotency-associated transcriptional network comprised of signal transducer and activator of transcription 3, SOX2, OCT4, and Nanog. Stimulation of the pluripotency network may have significant implications for hepatocellular oncogenesis via genesis and maintenance of TICs. It is important to understand how HCV induces liver cancer through genesis of TICs so that better prevention and treatment can be found. This article reviews the oncogenic pathways to generate TICs.

Hepatitis C virus and hepatocellular carcinoma

Hepatitis C virus (HCV), a hepatotropic virus, is a single stranded-positive RNA virus of ~9,600 nt. length belonging to the Flaviviridae family. HCV infection causes acute hepatitis, chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC). It has been reported that HCV-coding proteins interact with host-cell factors that are involved in cell cycle regulation, transcriptional regulation, cell proliferation and apoptosis. Severe inflammation and advanced liver fibrosis in the liver background are also associated with the incidence of HCV-related HCC. In this review, we discuss the mechanism of hepatocarcinogenesis in HCV-related liver diseases.

HCV enters the twenty-first century

Almost one-third of Americans infected with human immunodeficiency virus (HIV) and 7 million worldwide are coinfected with hepatitis C virus (HCV). The principal route of HCV spread in the US is injection drug use but there are recent reports of outbreaks of acute HCV infection among HIV-infected men who have sex with men. With increased survival as a result of highly active antiretroviral therapy, HCV-associated liver disease has become a leading cause of death in HIV-infected individuals. Currently, telaprevir and boceprevir, both NS3/NS4A inhibitors that significantly improve sustained response when added to pegylated interferon and ribavirin, are approved only for HCV monoinfection. The optimal combination of agents, therapy durations and the timing of treatment remain major challenges in coinfected patients.

Neuromuscular diseases associated with chronic hepatitis C virus infection

Hepatitis C virus (HCV) infection is a growing international health problem, and more than 170 million people are chronic carriers. Up to 50% of HCV-positive patients develop at least one extrahepatic manifestation during the course of disease. To varying degrees of certainty, there is evidence of an association between chronic HCV infection and a variety of neuromuscular diseases. The pathogenesis of most extrahepatic diseases remains unclear but possibly includes HCV lymphotropism and/or HCV-induced autoantibodies. The therapeutic approach to HCV-associated autoimmune disorders entails eradication of HCV with one of the recombinant interferon-alpha preparations with or without additional immunosuppressive drugs.

Viral hepatitis induces hepatocellular cancer: what can we learn from epidemiology comparing iran and worldwide findings?

CONTEXT

Several risk factors play the role in the development of hepatocellular carcinoma (HCC) from which chronic hepatitis B and C infections are the most important ones. DNA integration of hepatitis viruses alters the function of critical genes promoting malignant transformation of virus-infected liver cells.

EVIDENCE ACQUISITION

There are remarkable geographic differences in prevalence of chronic viral hepatitis and incidence of HCC. Middle Eastern countries are characterized by a moderate to high prevalence rate of chronic viral hepatitis in the population. This review discusses about epidemiologic findings of hepatitis B and C infections, and HCC, as well as focuses on Middle East countries, particularly Iran. We provide an overview about risk factors, prevention and treatment, and bring up the role of HCC induced by chronic viral hepatitis.

RESULTS

Vaccination against hepatitis B virus (HBV) in the early childhood is highly effective to lower infection rates, substantially. For hepatitis C, adequate hygiene when dealing with human blood and screening programs for blood donors can mainly reduce infection rates. As HCC is strongly associated with chronic viral hepatitis, prevention against the infection is crucial for preventing against HCC too.

CONCLUSIONS

Although prevention and treatment of chronic hepatitis B and C have improved within the last decades even in high-risk countries, effective and sustainable reduction of these infections still needs more actions.

Hepatitis C virus and cellular stress response: implications to molecular pathogenesis of liver diseases

Infection with hepatitis C virus (HCV) is a leading risk factor for chronic liver disease progression, including steatosis, cirrhosis, and hepatocellular carcinoma. With approximately 3% of the human population infected worldwide, HCV infection remains a global public health challenge. The efficacy of current therapy is still limited in many patients infected with HCV, thus a greater understanding of pathogenesis in HCV infection is desperately needed. Emerging lines of evidence indicate that HCV triggers a wide range of cellular stress responses, including cell cycle arrest, apoptosis, endoplasmic reticulum (ER) stress/unfolded protein response (UPR), and autophagy. Also, recent studies suggest that these HCV-induced cellular responses may contribute to chronic liver diseases by modulating cell proliferation, altering lipid metabolism, and potentiating oncogenic pathways. However, the molecular mechanism underlying HCV infection in the pathogenesis of chronic liver diseases still remains to be determined. Here, we review the known stress response activation in HCV infection in vitro and in vivo, and also explore the possible relationship of a variety of cellular responses with the pathogenicity of HCV-associated diseases. Comprehensive knowledge of HCV-mediated disease progression shall shed new insights into the discovery of novel therapeutic targets and the development of new intervention strategy.

The suppression effects of desacetyluvaricin on hepatocellular carcinoma and its possible mechanism

OBJECTIVE

To investigate the anticancer effects of desacetyluvaricin (DES) on hepatocellular carcinoma (HCC) in vitro, and to study its mechanism.

MATERIALS AND METHODS

Using DES and cisplatin (DDP) to intervene the cell lines of hepatocarcinoma G2.2.15 (HepG2.2.15) and HepG2, by detecting the expression of HBxAg by immunofluorescence method, the cell cycle and apoptosis by flow cytometry method (FCM), and expression of NF-κB protein by ELISA.

RESULTS

DES and DDP showed to suppress proliferation of HepG2.2.15 and HepG2; they increase the S-phase cells and decrease G2/M phase cells. DES and DDP both could promote the apoptosis and reduce the expression of NF-κB on the cell line. DES and DDP both can suppress the expression of HbxAg in HepG2.2.15. There were no statistical differences of the above results between these two drugs (P > 0.05).

CONCLUSIONS

DES possesses anticancer effect on hepatocarcinoma. The possible mechanism might be due to promotion the apoptosis of the cancer cells, and downregulate the expression of HBx andNF-κB protein. DES is a kind of natural products, Because of the lighter clinical side effects; our observations suggest that DES has the potential to be explored as an effective anticancer agent for HCC.

Hepatitis C virus infection enhances TNFα-induced cell death via suppression of NF-κB

Hepatitis C virus (HCV) infection results in liver injury and long-term complications, such as liver cirrhosis and hepatocellular carcinoma. Liver injury in HCV infection is believed to be caused by host immune responses, not by viral cytopathic effects. Tumor necrosis factor-alpha (TNF-α) plays a pivotal role in the inflammatory processes of hepatitis C. TNF-α induces cell death that can be ameliorated by nuclear factor kappaB (NF-κB) activation. We investigated the regulation of TNF-α signal transduction in HCV-infected cells and identified HCV proteins responsible for sensitization to TNF-α-induced cell death. We studied the effect of HCV infection on TNF-α signal transduction using an in vitro HCV infection model (JFH-1, genotype 2a) with Huh-7 and Huh-7.5 cells. We found that TNF-α-induced cell death significantly increased in HCV-infected cells. HCV infection diminished TNF-α-induced phosphorylation of IκB kinase (IKK) and inhibitor of NF-κB (IκB), which are upstream regulators of NF-κB activation. HCV infection also inhibited nuclear translocation of NF-κB and expression of NF-κB-dependent anti-apoptotic proteins, such as B-cell lymphoma--extra large (Bcl-xL), X-linked inhibitor of apoptosis protein (XIAP), and the long form of cellular-FLICE inhibitory protein (c-FLIP). Decreased levels of Bcl-xL, XIAP, and c-FLIP messenger RNA and protein were also observed in livers with chronic hepatitis C. Transfection with plasmids encoding each HCV protein revealed that core, nonstructural protein (NS)4B, and NS5B attenuated TNF-α-induced NF-κB activation and enhanced TNF-α-induced cell death.

CONCLUSION

HCV infection enhances TNF-α-induced cell death by suppressing NF-κB activation through the action of core, NS4B, and NS5B. This mechanism may contribute to immune-mediated liver injury in HCV infection.

Liver X receptor α-mediated regulation of lipogenesis by core and NS5A proteins contributes to HCV-induced liver steatosis and HCV replication

Molecular mechanisms contributing to hepatitis C virus (HCV)-associated steatosis are not well established, although HCV gene expression has been shown to alter host cell cholesterol/lipid metabolism. As liver X receptors (LXRs) play a role as key modulators of metabolism signaling in the development of steatosis, we aimed to investigate in an HCV in vitro model the effect of HCV NS5A protein, core protein, and viral replication on the intracellular lipid accumulation and the LXRα-regulated expression of lipogenic genes. The effects of LXRα siRNA or agonist GW3965 treatment on lipogenesis and HCV replication capacity in our HCV replicon system were also examined. NS5A- and core-expressing cells and replicon-containing cells exhibited an increase of lipid accumulation by inducing the gene expression and the transcriptional activity of LXRα, and leading to an increased expression of its lipogenic target genes sterol regulatory element binding protein-1c, peroxisome proliferator-activated receptor-γ, and fatty acid synthase. Transcriptional induction by NS5A protein, core protein, and viral replication occurred via LXR response element activation in the lipogenic gene promoter. No physical association between HCV proteins and LXRα was observed, whereas NS5A and core proteins indirectly upregulated LXRα through the phosphatidylinositol 3-kinase pathway. Finally, it was found that LXRα knockdown or agonist-mediated LXRα induction directly regulated HCV-induced lipogenesis and HCV replication efficiency in replicon-containing cells. Combined, our data suggest that LXRα-mediated regulation of lipogenesis by core and NS5A proteins may contribute to HCV-induced liver steatosis and to the efficient replication of HCV.

HCV-related nervous system disorders

Chronic infection with hepatitis C virus (HCV) is associated with a wide spectrum of extrahepatic manifestations, affecting different organ systems. Neurological complications occur in a large number of patients and range from peripheral neuropathy to cognitive impairment. Pathogenetic mechanisms responsible for nervous system dysfunction are mainly related to the upregulation of the host immune response with production of autoantibodies, immune complexes, and cryoglobulins. Alternative mechanisms include possible extrahepatic replication of HCV in neural tissues and the effects of circulating inflammatory cytokines and chemokines.

Microbes-induced EMT at the crossroad of inflammation and cancer

It is noteworthy that bacterial or viral infections, and the resulting chronic inflammation, have been shown to predispose individuals to certain types of cancer. Remarkably, these microbes upregulated some transcription factors involved in the regulation of the epithelial to mesenchymal transition, referred herein as EMT. EMT is a cellular process that consists in the conversion of epithelial cell phenotype to a mesenchymal phenotype. Under physiological conditions EMT is clearly important for embryogenesis, organ development, wound repair and tissue remodeling. However, EMT may also be activated under pathologic conditions, more particularly in carcinogenesis and metastatic progression. In this review, we make a parallel between microbes- and growth factors- induced transcription factors. A unifying EMT model then emerges that may help in understanding the development of microbial pathogenesis and in defining new potential future therapeutic strategy in treating diseases linked to infections.

HCV NS4B induces apoptosis through the mitochondrial death pathway

The hepatitis C virus (HCV) NS4B protein is known to induce the formation of a membranous web that is thought to be the site of viral RNA replication. However, the exact functions of NS4B remain poorly characterized. In this study, we found that NS4B induced apoptosis in 293T cells and Huh7 cells, as confirmed by Hoechst staining, DNA fragmentation, and annexin V/PI assays. Furthermore, protein immunoblot analysis demonstrated that NS4B triggered the cleavage of caspase 3, caspase 7, and poly(ADP-ribose) polymerase (PARP). Further studies revealed that NS4B induced the activation of caspase 9, the reduction of mitochondrial membrane potential and the release of cytochrome c from the mitochondria. However, NS4B expression did not trigger XBP1 mRNA splicing and increase the expression of binding immunoglobulin protein (BiP, or GRP78) and C/EBP homologous protein (CHOP), which serves as the indicators of ER stress. Taken together, our results suggest that HCV NS4B induces apoptosis through the mitochondrial death pathway.

Enhancement of canonical Wnt/β-catenin signaling activity by HCV core protein promotes cell growth of hepatocellular carcinoma cells

BACKGROUND

The Hepatitis C virus (HCV) core protein has been implicated as a potential oncogene or a cofactor in HCV-related hepatocellular carcinoma (HCC), but the underlying mechanisms are unknown. Overactivation of the Wnt/β-catenin signaling is a major factor in oncogenesis of HCC. However, the pathogenesis of HCV core-associated Wnt/β-catenin activation remains to be further characterized. Therefore, we attempted to determine whether HCV core protein plays an important role in regulating Wnt/β-catenin signaling in HCC cells.

METHODOLOGY

Wnt/β-catenin signaling activity was investigated in core-expressing hepatoma cells. Protein and gene expression were examined by Western blot, immunofluorescence staining, RT-qPCR, and reporter assay.

PRINCIPAL FINDINGS

HCV core protein significantly enhances Tcf-dependent transcriptional activity induced by Wnt3A in HCC cell lines. Additionally, core protein increases and stabilizes β-catenin levels in hepatoma cell line Huh7 through inactivation of GSK-3β, which contributes to the up-regulation of downstream target genes, such as c-Myc, cyclin D1, WISP2 and CTGF. Also, core protein increases cell proliferation rate and promotes Wnt3A-induced tumor growth in the xenograft tumor model of human HCC.

CONCLUSIONS/SIGNIFICANCE

HCV core protein enhances Wnt/β-catenin signaling activity, hence playing an important role in HCV-associated carcinogenesis.

Chronic hepatitis C

The goal of antiviral therapy for patients with chronic hepatitis C virus (HCV) infection is to attain a sustained virologic response (SVR), which is defined as undetectable serum HCV-RNA levels at 6 months after the cessation of treatment. Major improvements in antiviral therapy for chronic hepatitis C have occurred in the past decade. The addition of ribavirin to interferon-alfa therapy and the introduction of pegylated interferon (PEG-IFN) have substantially improved SVR rates in patients with chronic hepatitis C. The optimization of HCV therapy with PEG-IFN and ribavirin continues to evolve. Studies are ongoing that use viral kinetics to tailor therapy to an individual's antiviral response and determine the ideal length of treatment to maximize the chance of SVR. Improved SVR can be achieved with new specific inhibitors that target the HCV NS3/4A protease and the NS5B polymerase. Several long-term follow-up studies have shown that SVR, when achieved, is associated with a very low risk of virologic relapse. Furthermore, antiviral therapy can reduce the morbidity and mortality rates associated with chronic hepatitis C by reducing fibrosis progression, the incidence of cirrhosis, and hepatocellular carcinoma.

Coevolution of the hepatitis C virus polyprotein sites in patients on combined pegylated interferon and ribavirin therapy

Genotype-specific sensitivity of the hepatitis C virus (HCV) to interferon-ribavirin (IFN-RBV) combination therapy and reduced HCV response to IFN-RBV as infection progresses from acute to chronic infection suggest that HCV genetic factors and intrahost HCV evolution play important roles in therapy outcomes. HCV polyprotein sequences (n = 40) from 10 patients with unsustainable response (UR) (breakthrough and relapse) and 10 patients with no response (NR) following therapy were identified through the Virahep-C study. Bayesian networks (BNs) were constructed to relate interrelationships among HCV polymorphic sites to UR/NR outcomes. All models showed an extensive interdependence of HCV sites and strong connections (P ≤ 0.003) to therapy response. Although all HCV proteins contributed to the networks, the topological properties of sites differed among proteins. E2 and NS5A together contributed ∼40% of all sites and ∼62% of all links to the polyprotein BN. The NS5A BN and E2 BN predicted UR/NR outcomes with 85% and 97.5% accuracy, respectively, in 10-fold cross-validation experiments. The NS5A model constructed using physicochemical properties of only five sites was shown to predict the UR/NR outcomes with 83.3% accuracy for 6 UR and 12 NR cases of the HALT-C study. Thus, HCV adaptation to IFN-RBV is a complex trait encoded in the interrelationships among many sites along the entire HCV polyprotein. E2 and NS5A generate broad epistatic connectivity across the HCV polyprotein and essentially shape intrahost HCV evolution toward the IFN-RBV resistance. Both proteins can be used to accurately predict the outcomes of IFN-RBV therapy.

TLRs, Alcohol, HCV, and Tumorigenesis

Chronic liver damage caused by viral infection, alcohol, or obesity can result in increased risk for hepatocellular carcinoma (HCC). Ample epidemiological evidence suggests that there is a strong synergism between hepatitis C virus (HCV) and alcoholic liver diseases (ALD). The Toll-like receptor (TLR) signaling pathway is upregulated in chronic liver diseases. Alcoholism is associated with endotoxemia that stimulates expression of proinflammatory cytokine expression and inflammation in the liver and fat tissues. Recent studies of HCC have centered on cancer-initiating stem cell (CSC), including detection of CSC in cancer, identification of CSC markers, and isolation of CSC from human HCC cell lines. Synergism between alcohol and HCV may lead to liver tumorigenesis through TLR signaling.

Virus-specific mechanisms of carcinogenesis in hepatitis C virus associated liver cancer

The development of hepatocellular carcinoma (HCC) in persons who are persistently infected with hepatitis C virus (HCV) is a growing problem worldwide. Current antiviral therapies are not effective in many patients with chronic hepatitis C, and a greater understanding of the factors leading to progression of HCC will be necessary to design novel approaches to prevention of HCV-associated HCC. The lack of a small animal model of chronic HCV infection has hampered understanding of these factors. As HCV is an RNA virus with little potential for integration of its genetic material into the host genome, the mechanisms underlying HCV promotion of cancer are likely to differ from other models of viral carcinogenesis. In patients persistently infected with HCV, chronic inflammation resulting from immune responses against infected hepatocytes is associated with progressive fibrosis and cirrhosis. Cirrhosis is an important risk factor for HCC independent of HCV infection, and a majority of HCV-associated HCC arises in the setting of cirrhosis. However, a significant minority arises in the absence of cirrhosis, indicating that cirrhosis is not a prerequisite for cancer. Other lines of evidence suggest that direct, virus-specific mechanisms may be involved. Transgenic mice expressing HCV proteins develop cancer in the absence of inflammation or immune recognition of the transgene. In vitro studies have revealed multiple interactions of HCV-encoded proteins with cell cycle regulators and tumor suppressor proteins, raising the possibility that HCV can disrupt control of cellular proliferation, or impair the cell's response to DNA damage. A combination of virus-specific, host genetic, environmental and immune-related factors are likely to determine the progression to HCC in patients who are chronically infected with HCV. Here, we summarize current knowledge of the virus-specific mechanisms that may contribute to HCV-associated HCC.

Hepatic insulin resistance is associated with increased apoptosis and fibrogenesis in nonalcoholic steatohepatitis and chronic hepatitis C

BACKGROUND & AIMS

We aimed to elucidate whether hepatic insulin resistance may contribute to hepatocyte apoptosis and fibrogenesis in nonalcoholic fatty liver disease (NAFLD) and in chronic hepatitis C virus (HCV) infection.

METHODS

Twenty-seven nonalcoholic steatosis (NAST), 24 nonalcoholic steatohepatitis (NASH), 71 HCV, and 29 patients with histological normal liver (NL) were studied. Real-time PCR, the TUNEL assay, and Western blots were used to assess insulin-signaling molecules, hepatocyte apoptosis, antiapoptotic mediators, active caspase 3, and type I collagen in liver biopsies. HCV core-transfected human hepatocytes were used as an in vitro model.

RESULTS

In NAFLD patients, hepatic levels of insulin receptor substrate (IRS) 1, IRS2 2, the p85α subunit of phosphatidylinositol 3-kinase (p85α), phosphorylated protein kinase B (pAkt), phosphorylated forkhead box-containing protein O subfamily-1 (FoxO), and phosphorylated 5' adenosine monophosphate-activated protein kinase (pAMPK) as well as the antiapoptotic mediators B-cell lymphoma 2 protein (Bcl-2) and myeloid cell leukemia protein-1 (Mcl-1) were significantly lower in NASH than in NAST and NL. Furthermore, hepatocyte apoptosis and increased active caspase 3 were only present in NASH. In HCV patients, hepatic insulin signaling was markedly impaired, regardless of viral genotype and the presence of steatosis paralleled with enhanced apoptosis. In cultured human hepatocytes, HCV core protein decreased pAkt and increased phosphorylation of c-Jun N-terminal kinase (JNK). This effect was more pronounced in lipid-loaded hepatocytes.

CONCLUSIONS

Hepatic insulin signaling is impaired in NASH and HCV patients, and downregulation of insulin-sensitive targets is associated with increased apoptosis and fibrogenesis in both conditions. JNK might be a target for HCV-induced insulin resistance.

Tumour necrosis factor alpha (TNF-alpha) stimulation of cells with established dengue virus type 2 infection induces cell death that is accompanied by a reduced ability of TNF-alpha to activate nuclear factor kappaB and reduced sphingosine kinase-1 activity

Tumor necrosis factor alpha (TNF-α) has an antiviral role in some infections but in dengue virus (DENV) infection it is linked to severe pathology. We have previously shown that TNF-α stimulation cannot activate nuclear factor κB (NF-κB) to the fullest extent in DENV-2-infected cells. Here, we investigate further responses of DENV-2-infected cells to TNF-α, focussing particularly on cell death and pro-survival signals. TNF-α stimulation of productively DENV-2-infected monocyte-derived macrophages or HEK-293 cells induced caspase-3-mediated cell death. While TNF-α induced comparable degradation of the inhibitor of NF-κB alpha (IκB-α) and NF-κB activation in mock-infected and DENV-2-infected cells early in infection, later in infection and coinciding with TNF-α-induced cell death, TNF-α-stimulated IκB-α degradation and NF-κB activation was reduced. This was associated with reduced levels of sphingosine kinase-1 (SphK1) activity in DENV-2-infected cells; SphK1 being a known mediator of TNF-α-stimulated survival signals. Transfection experiments demonstrated inhibition of TNF-α-stimulated NF-κB activation by expression of DENV-2 capsid (CA) but enhancement by DENV-2 NS5 protein. DENV-2 CA alone, however, did not induce TNF-α-stimulated cell death or inhibit SphK1 activity. Thus, productively DENV-2-infected cells have compromised TNF-α-stimulated survival pathways and show enhanced susceptibility to TNF-α-stimulated cell death, suggesting a role for TNF-α in the killing of healthy productively DENV-2-infected cells. Additionally, the altered ability of TNF-α to activate NF-κB as infection progresses is reflected by the opposing actions of DENV-2 CA and NS5 proteins on TNF-α-stimulated NF-κB activation and could have important consequences for NF-κB-driven release of inflammatory cytokines.

Tumor necrosis factor receptor 1 expression is upregulated in dendritic cells in patients with chronic HCV who respond to therapy

The present studies assessed the level of tumor necrosis factor receptor (TNFR) expression in peripheral blood mononuclear cells (PBMCs) subsets from patients with chronic HCV undergoing interferon α/ribavirin-based therapy (Ifn/R). Methods. TNFR family member mRNA expression was determined using quantitative real-time PCR assays (RTPCRs) in PBMC from 39 HCV+ patients and 21 control HCV− patients. Further subset analysis of HCV + patients (untreated (U), sustained virological responders (SVR), and nonresponders (NR)/relapsers (Rel)) PBMC was performed via staining with anti-CD123, anti-CD33, anti-TNFR1 or via RTPCR for TNFR1 mRNA. Results. A similar level of TNFR1 mRNA in PBMC from untreated HCV+ genotype 1 patients and controls was noted. TNFR1 and TNFR2 mRNA levels in PBMC from HCV+ patients with SVR were statistically different than levels in HCV(−) patients. A significant difference was noted between the peak values of TNFR1 of the CD123+ PBMC isolated from SVR and the NR/Rel. Conclusion. Upregulation of TNFR1 expression, occurring in a specific subset of CD123+ dendritic cells, appeared in HCV+ patients with SVR.

Functional characterization of core genes from patients with acute hepatitis C virus infection

BACKGROUND

The hepatitis C virus (HCV) core protein is implicated in diverse aspects of HCV-induced pathogenesis. There is a paucity of information on core in acute hepatitis C infection.

METHODS

We analyzed core gene sequences and protein functions from 13 patients acutely infected with HCV genotype 1.

RESULTS

Although core isolates differed slightly between patients, core quasispecies were relatively homogeneous within each patient. In 2 of 4 patients studied temporally, core quasispecies did not change over time. Comparison with more than 2700 published core isolates indicated that amino acid changes from a prototype reference strain found in acute core isolates were present in chronically infected persons at low frequency (6.4%; range, 0%-32%). Core isolates associated with lipid droplets to similar degrees in Huh7 cells. Core diffusion in cells was not affected by nonconservative changes F130L and G161S in the lipid targeting domain of core. Core isolates inhibited interferon-stimulated response element- and nuclear factor kappaB-dependent transcription and tumor necrosis factor alpha-induced nuclear translocation of nuclear factor kappaB and were also secreted from Huh7 cells.

CONCLUSIONS

The data suggest that upon transmission, core quasispecies undergo genetic homogenization associated with amino acid changes that are rarely found in chronic infection and that, despite genetic variation, acute core isolates retain similar functions in vitro.

Role of nuclear factor kappaB in liver health and disease

NF-kappaB (nuclear factor kappaB) is a heterodimeric transcription factor that is constitutively expressed in all cell types and has a central role as a transcriptional regulator in response to cellular stress. In the present review, we discuss the role of NF-kappaB signalling in the maintenance of liver homoeostasis as well as in the pathogenesis of a wide variety of conditions affecting the liver, including viral hepatitis, steatohepatitis, cirrhosis and hepatocellular carcinoma. Much of the current knowledge of NF-kappaB signalling in the liver relates to the canonical pathway, the IKK [IkappaB (inhibitor of kappaB) kinase] complex and the RelA subunit. We explore the weaknesses of the experimental approaches to date and suggest that further work is needed to investigate in detail the discreet functions of each of the Rel subunits in liver physiology and disease.

Impact of amino acid substitutions in the core region of HCV on multistep hepatocarcinogenesis

AIM

The core protein of hepatitis C virus (HCV) has multiple functions for not only viral replication but also hepatocellular carcinogenesis. A significant association of the substitutions in the core region with hepatocarcinogenesis has recently been reported. In this report, we evaluated the association of the substitutions in the core region with multistep hepatocarcinogenesis.

METHODS

Sixty-nine non-cancerous and cancerous liver tissues were obtained from the patients with primary developed hepatocellular carcinoma (HCC) due to HCV and 17 cirrhotic liver tissues were obtained from the patients without HCC. A sequence analysis of the core protein of HCV was performed and the association between the substitution rates in the core gene and the degree of fibrosis or steatosis during the primary development of HCC and tumor differentiation was analyzed.

RESULTS

The substitution rates of amino acid 70, 75, 91 and 147 exceeded 25% (amino acid 70, 51%; 75, 45%; 91, 36%; 147, 30%). All substitution rates were comparable among cancerous and non-cancerous region of patients with HCC and non-cancerous region without HCC. The substitution rates of these four amino acids were not associated with the degree of fibrosis, steatosis or tumor differentiation during the primary development of HCC. In addition, the substitution rates were comparable between the patients with or without HCC. The cumulative substitution numbers in the core region were also not associated with the degree of fibrosis and steatosis.

CONCLUSIONS

It is possible that the substitutions in the core region are not associated with HCV-related multistep hepatocarcinogenesis.