glycoprotein-e2--hepatitis-c-virus and Liver-Cirrhosis

The E2 envelope glycoprotein of the hepatitis C virus (HCV) is a major target of broadly neutralizing antibodies that are closely related to a spontaneous cure of HCV infection. There is still no data about the diversity of E2-specific antibodies (Abs) glycosylation. The aim of this study was to analyze the level and sialylation of E2 IgG Abs, the relation of the respective changes to hepatic fibrosis (F) progression and their possible association with the efficacy of interferon-

Topics: Adult; Antibodies, Viral; Antiviral Agents; Genotype; Glycosylation; Hepacivirus; Hepatitis C; Humans; Immunoglobulin G; Interferon alpha-2; Liver Cirrhosis; Middle Aged; Ribavirin; Treatment Outcome; Viral Envelope Proteins; Viral Load; Young Adult

Hepatitis C virus (HCV) is one of the leading causes of chronic liver inflammatory disease (hepatitis), which often leads to more severe diseases, such as liver fibrosis, cirrhosis, and hepatocellular carcinoma. Liver fibrosis, in particular, is a major pathogenic consequence of HCV infection, and transforming growth factor β1 (TGF-β1) plays a key role in its pathogenesis. Several HCV proteins have been suggested to either augment or suppress the expression of TGF-β1 by HCV-infected cells. Here, we report that TGF-β1 levels are elevated in HCV-infected hepatocytes cultured in vitro and in liver tissue of HCV patients. Notably, the level of TGF-β1 in media from in vitro-cultured HCV-infected hepatocytes was high enough to activate primary hepatic stellate cells isolated from rats. This indicates that TGF-β1 secreted by HCV-infected hepatocytes is likely to play a key role in the liver fibrosis observed in HCV patients. Moreover, we showed that HCV E2 protein triggers the production of TGF-β1 by HCV-infected cells through overproduction of glucose-regulated protein 94 (GRP94).. Hepatic fibrosis is a critical step in liver cirrhosis caused by hepatitis C virus infection. It is already known that immune cells, including Kupffer cells, mediate liver fibrosis. Recently, several papers have suggested that HCV-infected hepatocytes also significantly produce TGF-β1. Here, we provide the first examination of TGF-β1 levels in the hepatocytes of HCV patients. Using an HCV culture system, we showed that HCV infection increases TGF-β1 production in hepatocytes. Furthermore, we confirmed that the amount of TGF-β1 secreted by HCV-infected hepatocytes was sufficient to activate primary hepatic stellate cells. To understand the molecular basis of TGF-β1 production in HCV-infected hepatocytes, we used HCV replicons and various stable cell lines. Finally, we elucidated that HCV E2 triggered TGF-β1 secretion via GRP94 mediated NF-κB activation. This study contributes to the understanding of liver fibrosis by HCV and suggests a new potential target (GRP94) for blocking liver cirrhosis in HCV patients.

Topics: Animals; Cells, Cultured; Culture Media, Conditioned; Hepacivirus; Hepatic Stellate Cells; Hepatitis C; Hepatocytes; Host-Pathogen Interactions; Humans; Liver Cirrhosis; Membrane Glycoproteins; Rats, Sprague-Dawley; Transforming Growth Factor beta1; Viral Envelope Proteins

Hypervariable region 1 (HVR1) of hepatitis C virus (HCV) comprises the first 27 N-terminal amino acid residues of E2. It is classically seen as the most heterogeneous region of the HCV genome. In this study, we assessed HVR1 evolution by using ultradeep pyrosequencing for a cohort of treatment-naive, chronically infected patients over a short, 16-week period. Organization of the sequence set into connected components that represented single nucleotide substitution events revealed a network dominated by highly connected, centrally positioned master sequences. HVR1 phenotypes were observed to be under strong purifying (stationary) and strong positive (antigenic drift) selection pressures, which were coincident with advancing patient age and cirrhosis of the liver. It followed that stationary viromes were dominated by a single HVR1 variant surrounded by minor variants comprised from conservative single amino acid substitution events. We present evidence to suggest that neutralization antibody efficacy was diminished for stationary-virome HVR1 variants. Our results identify the HVR1 network structure during chronic infection as the preferential dominance of a single variant within a narrow sequence space.. HCV infection is often asymptomatic, and chronic infection is generally well established in advance of initial diagnosis and subsequent treatment. HVR1 can undergo rapid sequence evolution during acute infection, and the variant pool is typically seen to diverge away from ancestral sequences as infection progresses from the acute to the chronic phase. In this report, we describe HVR1 viromes in chronically infected patients that are defined by a dominant epitope located centrally within a narrow variant pool. Our findings suggest that weakened humoral immune activity, as a consequence of persistent chronic infection, allows for the acquisition and maintenance of host-specific adaptive mutations at HVR1 that reflect virus fitness.

Topics: Adult; Aged; Aging; Amino Acid Sequence; Amino Acid Substitution; Antibodies, Neutralizing; Base Sequence; Female; Hepacivirus; Hepatitis C Antibodies; Hepatitis C, Chronic; Humans; Immunity, Humoral; Immunoglobulin G; Liver Cirrhosis; Male; Middle Aged; Molecular Sequence Data; Sequence Analysis, RNA; Viral Envelope Proteins; Viral Proteins; Young Adult

Hepatitis C virus (HCV) causes chronic hepatitis leading to liver fibrosis and autoimmune diseases. AIMP1/p43 is a multifunctional protein initially known as a cofactor of aminoacyl tRNA synthetase complex. Its function includes negative regulation of TGF-β signaling and suppression of Lupus-like autoimmune disease by inhibition of surface expression of gp96. HCV E2 was shown to directly interact with AIMP1/p43 by GST pulldown assay and coimmunoprecipitation. Their subcellular colocalization was observed in an immunofluorescence confocal microscopy. We showed that HCV E2 led to degradation of AIMP1/p43 in two ways. First, in the presence of HCV E2, endogenous AIMP1/p43 was shown to be degraded in an ubiquitin-dependent proteasome pathway. Second, grp78, an ER chaperone, was shown to interact with and stabilize AIMP1/p43. And HCV E2 inhibited this interaction leading to reduction of cellular AIMP1/p43. The degradation of AIMP1/p43 by HCV E2 resulted in increase of TGF-β signaling and cell surface expression of gp96. Thus we suggest that these are novel mechanisms responsible for liver fibrosis and autoimmune diseases caused by HCV.

Topics: Autoimmune Diseases; Blotting, Western; Cell Line, Tumor; Cell Membrane; Cytokines; Endoplasmic Reticulum Chaperone BiP; Heat-Shock Proteins; HEK293 Cells; Humans; Liver Cirrhosis; Membrane Glycoproteins; Microscopy, Fluorescence; Neoplasm Proteins; Proteasome Endopeptidase Complex; Protein Binding; Proteolysis; RNA Interference; RNA-Binding Proteins; Signal Transduction; Transforming Growth Factor beta; Up-Regulation; Viral Envelope Proteins

Hepatitis C virus (HCV) is a major health problem in developing countries including Pakistan. Chronic HCV infection results in progressive liver disease including fibrosis, cirrhosis, insulin resistance and eventually hepatocellular carcinoma (HCC). Ionotrophic purinergic (P2X) receptors are identified to involve in a spectrum of physiological and pathophysiological processes. However, the role of P2X receptors in HCV liver associated diseases still remains to be investigated. The current study was designed to identify the presence of P2X receptors in human liver cells. Furthermore, it investigates the response of P2X receptors towards HCV structural proteins (E1E2). To determine that how many isoforms of P2X receptors are expressed in human liver cells, human hepatoma cell line (Huh-7) was used. Transcripts (mRNA) of five different isoforms of P2X receptors were identified in Huh-7 cells. To examine the gene expression of identified isoforms of P2X receptors in presence of HCV structural proteins E1E2, Huh-7/E1E2 cell line (stably expressing HCV structural proteins E1E2) was used. The results showed significant increase (6.2 fold) in gene expression of P2X4 receptors in Huh-7/E1E2 cells as compared to control Huh-7 cells. The findings of present study confirmed the presence of transcripts of five different isoforms of P2X receptors in human liver cells and suggest that P2X4 receptors could be represented an important component of the purinergic signaling complex in HCV induced liver pathogenesis.

Topics: Carcinoma, Hepatocellular; Cell Line, Tumor; Gene Expression; Genotype; Hepacivirus; Hepatitis C; Humans; Liver; Liver Cirrhosis; Liver Neoplasms; Plasmids; Protein Isoforms; Real-Time Polymerase Chain Reaction; Receptors, Purinergic P2X4; RNA, Messenger; Signal Transduction; Transfection; Viral Envelope Proteins

We evaluated the expression of hepatitis C virus (HCV) antigen on liver grafts by immunohistochemical staining (IHS) using IG222 monoclonal antibody (mAb) against HCV-envelope 2 (E2).. The study material was 84 liver biopsy specimens obtained from 28 patients who underwent living donor liver transplantation (LDLT) for HCV infection. The biopsy samples were examined histopathologically, and by IHS using IG222 mAb against HCV-E2. Serum HCV-RNA level was measured in all patients. The IHS grades were compared among the three groups classified according to the time elapsed from LDLT (at 1-30, 31-179 and > or =180 days post-LDLT) and among four post-transplant conditions, including acute cellular rejection (ACR).. Immunoreactivity to IG222 was detected in 78.6% of the specimens obtained during the first month after LDLT, and there were no significant differences on the IHS grades between the three groups classified according to the time elapsed from LDLT. The IHS grades were significantly stronger in definite recurrent HCV (n = 12) and probable recurrent HCV (n = 7) than in definite ACR (n = 7) and other complications (n = 8). There were no significant differences in serum HCV-RNA levels among the four post-transplant conditions. There was no significant correlation between the IHS grades using IG222 mAb and serum HCV-RNA levels when data of 84 liver biopsy specimens were analyzed.. Constant HCV-E2 expression was observed in liver biopsy specimens obtained 1 month or longer. The strong HCV-E2 expression on liver grafts were associated with recurrent hepatitis C after LDLT, but the serum HCV-RNA levels were not.

Topics: Antibodies, Monoclonal; Biopsy; Female; Hepacivirus; Hepatitis C; Humans; Immunohistochemistry; Liver; Liver Cirrhosis; Liver Transplantation; Living Donors; Male; Middle Aged; Recurrence; RNA, Viral; Severity of Illness Index; Time Factors; Viral Envelope Proteins

Hepatitis C virus (HCV) causes acute and chronic liver diseases in humans. Its two envelope glycoproteins, E1 and E2, provide a target for host immune recognition. HCV genotypes are classified into six genetic groups. To study the role of anti-HCV E1 and E2 (anti-E1E2) in HCV disease, the correlation between antibody level and viral load, genotype, disease severity and response to treatment was investigated. The levels of antibodies to HCV glycoproteins E1 and E2 antibodies were evaluated in 230 sera of patients with chronic hepatitis C by enzyme-linked immunosorbent assay. The antigens used were recombinant HCV glycoproteins derived from genotype 1 (H77c) and genotype 3 (UKN3A1.28). Seroreactivity was greater when sera were tested against antigen derived from their homologous genotype than against heterologous antigen. Reactivity against UKN3A1.28 in sera from patients infected with genotype 3 was significantly higher than corresponding reactivity between patients infected with genotype 1 and H77c. The seroreactivity was inversely proportional to the viral load and to the degree of liver fibrosis. The pre-treatment level of anti-E1E2 was higher in sustained responders to combination therapy. These results demonstrate that seroreactivity against E1E2 depends upon the genotypic origin of the E1E2 antigens and the infecting genotype, and suggest a possible protective effect of anti-E1E2 against disease progression.

Topics: Antibodies, Viral; Antiviral Agents; Enzyme-Linked Immunosorbent Assay; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Liver Cirrhosis; Severity of Illness Index; Statistics as Topic; Treatment Outcome; Viral Envelope Proteins; Viral Load

Detection and localization of Hepatitis C Virus (HCV) in liver tissue is useful for diagnostic purposes as well as to elucidate the mechanisms by which the virus participates in hepatocarcinogenesis. However, so far, a sensitive method for HCV detection at the cellular level is lacking. We describe here the application of a novel antibody, D4.12.9, developed against serum-derived HCV RNA-positive particles, for the detection of E2 proteins by immunohistochemistry in fixed, archived specimens including liver biopsies of HCV-infected patients and surgical specimens of hepatocellular carcinoma. We demonstrate that D4.12.9 is a powerful tool for sensitive and specific detection of HCV, independently of viral genotype. This approach has applications to diagnosis as well as exploratory pathological studies.

Topics: Antibodies, Monoclonal; Antibody Specificity; Hepacivirus; Hepatitis C; Hepatitis C Antigens; Humans; Immunohistochemistry; Liver; Liver Cirrhosis; Liver Neoplasms; Reproducibility of Results; Sensitivity and Specificity; Viral Envelope Proteins

End-stage liver disease as a result of chronic hepatitis C virus (HCV) infection is the main indication for liver transplant (LT), but allografts are systematically infected with HCV soon after transplant. Viral quasispecies are poorly described during the early posttransplant period.. For 17 patients who received an LT for HCV disease, plasma viral quasispecies evolution was determined by sequence analysis of hypervariable region 1 of the E2 envelope gene before transplant (BT), after 7 days (D7), and after 1 month (M1). T helper (Th)1/Th2 cytokine levels were determined concomitantly.. HCV quasispecies showed a significant decrease in amino acid diversity at D7 and M1, compared with BT (P<.05). A correlation was observed between low plasma tumor necrosis factor-alpha levels at D7 and decreased quasispecies amino acid complexity at the same date. Nucleic acid diversity was lower for genotype 1 than for genotype 3 infection (P<.05). The complexity and diversity of amino acids were lower in patients with hepatocellular carcinoma (HCC) BT than in those without HCC (P<.05). Conserved amino acid residues within quasispecies were shared by the whole cohort before and after LT.. Viral structural and/or host immunological features could favor the emergence of fitter HCV strains after LT.

Topics: Adult; Amino Acid Sequence; Carcinoma, Hepatocellular; Cytokines; Evolution, Molecular; Female; Genetic Variation; Genome, Viral; Hepacivirus; Hepatitis C, Chronic; Humans; Liver Cirrhosis; Liver Transplantation; Male; Middle Aged; Molecular Sequence Data; Viral Envelope Proteins; Viral Load

The hepatitis C virus (HCV) envelope E2 glycoprotein is a key molecule regulating the interaction of HCV with cell surface proteins. E2 binds the major extracellular loop of human CD81, a tetraspanin expressed on various cell types including hepatocytes and B lymphocytes. Regardless, information on the biological functions originating from this interaction are largely unknown. Since human hepatic stellate cells (HSC) express high levels of CD81 at the cell surface, we investigated the E2/CD81 interaction in human HSC and the possible effects arising from this interaction. Matrix metalloproteinase-2 (MMP-2; gelatinase A), a major enzyme involved in the degradation of normal hepatic extracellular matrix, was up-regulated following the interaction between E2 and CD81. In particular, by employing zymography and Western blot, we observed that E2 binding to CD81 induces a time-dependent increase in the synthesis and activity of MMP-2. This effect was abolished by preincubating HSC with an anti-CD81 neutralizing antibody. Similar effects were detected in NIH3T3 mouse fibroblasts transfected with human CD81 with identical time course features. In addition, E2/CD81 interaction in human HSC induced the up-regulation of MMP-2 by increasing activator protein-2/DNA binding activity via ERK/MAPK phosphorylation. Finally, suppression of CD81 by RNA interference in human HSC abolished the described effects of E2 on these cells, indicating that CD81 is essential for the activation of the signaling pathway leading to the up-regulation of MMP-2. These results suggest that HSC may represent a potential target for HCV. The interaction of HCV envelope with CD81 on the surface of human HSC induces an increased expression of MMP-2. Increased degradation of the normal hepatic extracellular matrix in areas where HCV is concentrated may favor inflammatory infiltration and further parenchymal damage.

Topics: Animals; Antigens, CD; Cells, Cultured; DNA; DNA-Binding Proteins; Hepatitis C, Chronic; Humans; Liver; Liver Cirrhosis; Matrix Metalloproteinase 2; Mice; NIH 3T3 Cells; Phosphorylation; Signal Transduction; Tetraspanin 28; Transcription Factor AP-2; Transcription Factors; Up-Regulation; Viral Envelope Proteins

CD81 is a surface-associated protein expressed in the membranes of mammalian cells. It has been suggested that CD81 interacts with hepatitis C virus E2 protein, and thus might facilitate the entry of HCV into hepatocytes. The envelope-binding site appears to involve amino acids (aa) 480-493 and 544-551 within the E2 glycoprotein. Little is known about the quasispecies genetic diversity of these two regions. We studied four patients who underwent transplantation for HCV-related cirrhosis and who developed recurrent hepatitis C. We evaluated HCV quasispecies diversity in serum samples obtained at the time of transplantation and at several time points thereafter. Quasispecies diversity was assessed by cloning and sequencing of viral isolates, with computer analysis of evolution models. The genetic distance in the region that spans aa 480 to 493 was 0.019 +/- 0.004 before the transplant, and 0.039 +/- 0.014 after the transplant (p=0.324). In the aa 544 to 551 region, the pre-transplant genetic distance was 0.012 +/- 0.008 and the post-transplant distance, 0.010 +/- 0.007 (p=0.890). There was also no significant difference between the number of nonsynonymous substitutions per nonsynonymous site before and after transplantation. In conclusion, the HCV genetic sequences of putative CD81 binding regions aa 480-493 and aa 544-551 did not diversify significantly after liver transplantation. This may favor HCV re-infection of the allograft after liver transplantation.

Topics: Amino Acid Sequence; Antigens, CD; Binding Sites; Genetic Variation; Hepacivirus; Hepatocytes; Humans; Liver Cirrhosis; Liver Transplantation; Molecular Sequence Data; Protein Binding; Reoperation; Reverse Transcriptase Polymerase Chain Reaction; RNA, Viral; Tetraspanin 28; Time Factors; Viral Envelope Proteins

The association of the severity of liver disease and the molecular evolution of hepatitis C virus (HCV) during chronic infection remains unclear and controversial. To address this we have studied the interpatient variability in the nucleotide sequence of two regions of the HCV genome, E1/E2, which contain the hypervariable region 1 and the nonstructural NS5b region, in a cohort of Irish female patients who were all recipients of a single source of HCV genotype 1b-contaminated anti-D immunoglobulin in 1977 and 1978 and who over the subsequent 20 years developed a spectrum of liver disease. In addition, quasispecies analysis was used to evaluate intrapatient variability in the E1/E2 region in four patients with mild and four with severe disease. Phylogenetic and evolutionary rate analyses of the nucleotide sequences demonstrated that there was no significant difference between those who developed mild disease and those who had progressed to severe disease or cirrhosis. These findings suggest that other factors, either additional viral or host, may be important in the pathogenesis and clinical outcome of chronic hepatitis C virus infection.

Topics: Amino Acid Sequence; Cohort Studies; Evolution, Molecular; Female; Genetic Variation; Hepacivirus; Hepatitis C, Chronic; Humans; Liver Cirrhosis; Molecular Sequence Data; Nucleotides; Phylogeny; Viral Envelope Proteins; Viral Nonstructural Proteins

The aim of this study was to determine whether expression of hepatitis C virus proteins alters hepatic morphology or function in the absence of inflammation.. Transgenic C57BL/6 mice with liver-specific expression of RNA encoding the complete viral polyprotein (FL-N transgene) or viral structural proteins (S-N transgene) were compared with nontransgenic littermates for altered liver morphology and function.. FL-N transcripts were detectable only by reverse-transcription polymerase chain reaction, and S-N transcripts were identified in Northern blots. The abundance of viral proteins was sufficient for detection only in S-N transgenic animals. There was no inflammation in transgenic livers, but mice expressing either transgene developed age-related hepatic steatosis that was more severe in males. Apoptotic or proliferating hepatocytes were not significantly increased. Hepatocellular adenoma or carcinoma developed in older male animals expressing either transgene, but their incidence reached statistical significance only in FL-N animals. Neither was ever observed in age-matched nontransgenic mice.. Constitutive expression of viral proteins leads to common pathologic features of hepatitis C in the absence of specific anti-viral immune responses. Expression of the structural proteins enhances a low background of steatosis in C57BL/6 mice, while additional low level expression of nonstructural proteins increases the risk of cancer.

Topics: Animals; Apoptosis; Cell Division; Fatty Liver; Female; Gene Expression Regulation, Viral; Hepacivirus; Hepatitis C, Chronic; Liver Cirrhosis; Liver Neoplasms, Experimental; Male; Mice; Mice, Inbred C3H; Mice, Inbred C57BL; Mice, Transgenic; Phenotype; RNA, Messenger; Transgenes; Viral Core Proteins; Viral Envelope Proteins; Viral Nonstructural Proteins; Viral Structural Proteins