Characterization of chronic HCV infection-induced apoptosis

Virological surveillance, molecular phylogeny, and evolutionary dynamics of hepatitis C virus subtypes 1a and 4a isolates in patients from Saudi Arabia

Hepatitis C virus (HCV) subtypes are pre-requisite to predict endemicity, epidemiology, clinical pathogenesis, diagnosis, and treatment of chronic hepatitis C infection. HCV genotypes 4 and 1 are the most prevalent in Saudi Arabia, however; less consensus data exist on circulating HCV subtypes in infected individuals. This study was aimed to demonstrate the virological surveillance, phylogenetic analysis, and evolutionary relationship of HCV genotypes 4 and 1 subtypes in the Saudi population with the rest of the world. Fifty-five clinical specimens from different parts of the country were analyzed based on 5′ untranslated region (5′ UTR) amplification, direct sequencing, and for molecular evolutionary genetic analysis. Pair-wise comparison and multiple sequence alignment were performed to determine the nucleotide conservation, nucleotide variation, and positional mutations within the sequenced isolates. The evolutionary relationship of sequenced HCV isolates with referenced HCV strains from the rest of the world was established by computing pairwise genetic distances and generating phylogenetic trees. Twelve new sequences were submitted to GenBank, NCBI database. The results revealed that HCV subtype 4a is more prevalent preceded by 1a in the Saudi population. Molecular phylogeny predicts the descendants’ relationship of subtype 4a isolates very close to Egyptian prototype HCV strains, while 1a isolates were homogeneous and clustering to the European and North American genetic lineages. The implications of this study highlight the importance of HCV subtyping as an indispensable tool to monitor the distribution of viral strains, to determine the risk factors of infection prevalence, and to investigate clinical differences of treatment outcomes among intergenotypic and intragenotypic isolates in the treated population.

Consensus small interfering RNA targeted to stem-loops II and III of IRES structure of 5' UTR effectively inhibits virus replication and translation of HCV sub-genotype 4a isolates from Saudi Arabia

Being the most conserved region of all hepatitis C virus (HCV) genotypes and sub-genotypes, the 5′ untranslated region (5′ UTR) of HCV genome signifies it’s importance as a potential target for anti-mRNA based treatment strategies like RNA interference. The advent and approval of first small interference RNA (siRNA) -based treatment of hereditary transthyretin-mediated amyloidosis for clinical use has raised the hopes to test this approach against highly susceptible viruses like HCV. We investigated the antiviral potential of consensus siRNAs targeted to stem-loops (SLs) II and III nucleotide motifs of internal ribosome entry site (IRES) structure within 5′ UTR of HCV sub-genotype 4a isolates from the Saudi population. siRNA inhibitory effects on viral replication and translation of full-length HCV genome were determined in a competent, persistent, and reproducible Huh-7 cell culture system maintained for one month. Maximal inhibition of RNA transcript levels of HCV-IRES clones and silencing of viral replication and translation of full-length virus genome was demonstrated by siRNAs targeted to SL-III nucleotide motifs of IRES in Huh-7 cells. siRNA Usi-169 decreased 5′ UTR RNA transcript levels of HCV-IRES clones up to 75% (P < 0.001) at 24 h post-transfection and 80% (P < 0.001) at 48 h treatment in Huh-7 cells. 5′ UTR-tagged GFP protein expression was significantly decreased from 70 to 80% in Huh-7 cells co-transfected with constructed vectors (i.e. pCR3.1/GFP/5′ UTR) and siRNA Usi-169 at 24 h and 48 h time-span. Viral replication was inhibited by more than 90% (P < 0.001) and HCV core (C) and hypervariable envelope glycoproteins (E1 and E2) expression was also significantly degraded by intracytoplasmic siRNA Usi-169 activity in persistent Huh-7 cell culture system. The findings unveil that siRNAs targeted to 5′ UTR-IRES of HCV sub-genotype 4a Saudi isolates show potent silencing of HCV replication and blocking of viral translation in a persistent in-vitro Huh-7 tissue culture system. Furthermore, we also elucidated that siRNA silencing of viral mRNA not only inhibits viral replication but also blocks viral translation. The results suggest that siRNA potent antiviral activity should be considered as an effective anti-mRNA based treatment strategies for further in-vivo investigations against less studied and harder-to-treat HCV sub-genotype 4a isolates in Saudi Arabia.

Antiviral Activity of Chitosan Nanoparticles Encapsulating Curcumin Against Hepatitis C Virus Genotype 4a in Human Hepatoma Cell Lines

Purpose

Current direct-acting antiviral agents for treatment of hepatitis C virus genotype 4a (HCV-4a) have been reported to cause adverse effects, and therefore less toxic antivirals are needed. This study investigated the role of curcumin chitosan (CuCs) nanocomposite as a potential anti-HCV-4a agent in human hepatoma cells Huh7.

Methods

Docking of curcumin and CuCs nanocomposite and binding energy calculations were carried out. Chitosan nanoparticles (CsNPs) and CuCs nanocomposite were prepared with an ionic gelation method and characterized with TEM, zeta size and potential, and HPLC to calculate encapsulation efficiency. Cytotoxicity studies were performed on Huh7 cells using MTT assay and confirmed with cellular and molecular assays. Anti-HCV-4a activity was determined using real-time PCR and Western blot.

Results

The strength of binding interactions between protein ligand complexes gave scores with NS3 protease, NS5A polymerase, and NS5B polymerase of -124.91, -159.02, and -129.16, for curcumin respectively, and -68.51, -54.52, and -157.63 for CuCs nanocomposite, respectively. CuCs nanocomposite was prepared at sizes 29-39.5 nm and charges of 33 mV. HPLC detected 4% of curcumin encapsulated into CsNPs. IC50 was 8 µg/mL for curcumin and 25 µg/mL for the nanocomposite on Huh7 but was 25.8 µg/mL and 34 µg/mL on WISH cells. CsNPs had no cytotoxic effect on tested cell lines. Apoptotic genes' expression revealed the caspase-dependent pathway mechanism. CsNPs and CuCs nanocomposite demonstrated 100% inhibition of viral entry and replication, which was confirmed with HCV core protein expression.

Conclusion

CuCs nanocomposite inhibited HCV-4a entry and replication compared to curcumin alone, suggesting its potential role as an effective therapeutic agent.

Schmallenberg virus induces apoptosis in Vero cell line via extrinsic and intrinsic pathways in a time and dose dependent manner

Schmallenberg virus (SBV), discovered in 2011 in Germany, is associated with clinical manifestations of fever, diarrhea, reduced milk yield, abortions and congenital malformations in ruminants. Despite many studies performed for SBV, there is no detailed research on in vitro apoptotic effect of SBV. This study is aimed to determine apoptosis pathways and role of pro-apoptotic and anti-apoptotic molecules in Vero cells infected with SBV. The study results showed that SBV induced apoptosis via both extrinsic and intrinsic pathways by activating both caspase-8 and caspase-9, respectively. Expression analyses of pro-apoptotic (Bax, Bak and Puma) and anti-apoptotic (Bcl-2 and Bcl-XL) genes revealed that SBV-induced apoptosis causes upregulation of pro-apoptotic genes, dominantly via Puma gene, whereas Bcl-2 and Bcl-XL genes were downregulated. In conclusion, this is the first detailed report about SBV induced apoptosis in the Vero cells via both extrinsic and intrinsic cascades and apoptosis induction is seem to be regulated by Puma.

Autophagy, apoptosis, vitamin D, and vitamin D receptor in hepatocellular carcinoma associated with hepatitis C virus

The aims of this study were to investigate the interplay between autophagy and apoptosis and to investigate the association between both of autophagy and apoptosis and vitamin D and its receptor in hepatitis C virus (HCV) viral infection and its implication in the progression into hepatocellular carcinoma (HCC).A cross-sectional study where serum levels of microtubule-associated protein 1A/1B-light chain 3 (LC3); marker of autophagy, caspase-3; marker of apoptosis, vitamin D3 and vitamin D receptor (VDR) were measured in healthy subjects as well as HCV and HCV-HCC patients using enzyme-linked immunosorbent assay technique.Collectively, the liver profile revealed hepatic dysfunctions in HCV patients with or without HCC. A significant reduction in the serum concentration levels LC3 and caspase-3 were observed referring to the down regulation of autophagy and host-mediated apoptosis in HCV patients with or without HCC. Deficiency of vitamin D and decreased levels of its receptor were observed in HCV and HCV-HCC patients.The perturbation in vitamin D/VDR axis, which modulates both of autophagy and apoptosis in HCV infection, may point out to its involvement and implication in the pathogenesis of HCV infection and the development of HCV-related HCC. Therefore, supplementation with vitamin D may not be the only solution to restore the vital biological functions of vitamin D but VDR-targeted therapy may be of great importance in this respect.

Molecular mechanisms of hepatitis C virus-induced hepatocellular carcinoma

Hepatitis C virus (HCV) is a major leading cause of hepatocellular carcinoma (HCC). HCV-induced hepatocarcinogenesis is a multistep process resulting from a combination of pathway alterations that are either caused directly by viral factors or immune mediated as a consequence of a chronic state of inflammation. Host genetic variation is now emerging as an additional element that contribute to increase the risk of developing HCC. The advent of direct-acting antiviral agents foresees a rapid decline of HCC rate in HCV patients. However, a full understanding of the HCV-mediated tumourigenic process is required to elucidate if pro-oncogenic signatures may persist after virus clearance, and to identify novel tools for HCC prevention and therapy. In this review, we summarize the current knowledge of the molecular mechanisms responsible for HCV-induced hepatocarcinogenesis.

HCV-Mediated Apoptosis of Hepatocytes in Culture and Viral Pathogenesis

Chronic Hepatitis C Virus (HCV) infection is associated with progressive liver injury and subsequent development of fibrosis and cirrhosis. The death of hepatocytes results in the release of cytokines that induce inflammatory and fibrotic responses. The mechanism of liver damage is still under investigation but both apoptosis and immune-mediated processes may play roles. By observing the changes in gene expression patterns in HCV-infected cells, both markers and the causes of HCV-associated liver injury may be elucidated. HCV genotype 1b virus from persistently infected VeroE6 cells induced a strong cytopathic effect when used to infect Huh7.5 hepatoma cells. To determine if this cytopathic effect was a result of apoptosis, ultrastructural changes were observed by electron microscopy and markers of programmed cell death were surveyed. Screening of a human PCR array demonstrated a gene expression profile that contained upregulated markers of apoptosis, including tumor necrosis factor, caspases and caspase activators, Fas, Bcl2-interacting killer (BIK) and tumor suppressor protein, p53, as a result of HCV genotype 1b infection. The genes identified in this study should provide new insights into understanding viral pathogenesis in liver cells and may possibly help to identify novel antiviral and antifibrotic targets.

Intrahepatic mRNA Expression of FAS, FASL, and FOXP3 Genes Is Associated with the Pathophysiology of Chronic HCV Infection

This study aimed to evaluate the relative mRNA expression of Fas receptor (FAS), Fas ligand (FASL), and forkhead box protein 3 (FOXP3) in liver biopsy specimens obtained from patients with viral and non-viral chronic hepatitis and correlate their expression with the fibrosis stage. A total of 51 liver biopsy specimens obtained from HBV (n = 6), HCV (n = 28), and non-viral hepatic disease (NVHD) (n = 9) patients and from individuals with normal liver histology (n = 8) (control—CT) were analyzed. Quantifications of the target genes were assessed using qPCR, and liver biopsies according to the METAVIR classification. The mRNA expression levels of FAS and FASL were lower in the CT group compared to the groups of patients. The increase in the mRNA expression of FAS and FASL was correlated with higher levels of inflammation and disease progression, followed by a decline in tissues with cirrhosis, and it was also associated with increased levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Higher mRNA expression of FOXP3 was observed in the HCV and NVHD groups, with the peak observed among patients with cirrhosis. The increased FOXP3 mRNA expression was positively correlated with increased FAS and FASL mRNA expression and the AST and ALT levels in all patients. Conclusions: These results suggest that regardless of the cause, the course of chronic liver disease may be modulated by the analyzed genes and correlated with an increase in regulatory T cells during the liver damage followed by hepatocyte destruction by Fas/FasL system and subsequent non specific lymphocytic infiltrate accumulation.

The core of hepatitis C virus pathogenesis

Capsid proteins form protective shells around viral genomes and mediate viral entry. However, many capsid proteins have additional and important roles for virus infection and in modulating cellular response to infection, with important consequences on pathogenesis. Infection by the Hepatitis C virus (HCV) can lead to liver steatosis, cirrhosis, and hepatocellular carcinoma. Herein, we focus on the role in pathogenesis of Core, the capsid protein of the HCV.

Hepatitis B and C virus-induced hepatitis: Apoptosis, autophagy, and unfolded protein response

AIM

To investigate the co-incidence of apoptosis, autophagy, and unfolded protein response (UPR) in hepatitis B (HBV) and C (HCV) infected hepatocytes.

METHODS

We performed immunofluorescence confocal microscopy on 10 liver biopsies from HBV and HCV patients and tissue microarrays of HBV positive liver samples. We used specific antibodies for LC3β, cleaved caspase-3, BIP (GRP78), and XBP1 to detect autophagy, apoptosis and UPR, respectively. Anti-HCV NS3 and anti-HBs antibodies were also used to confirm infection. We performed triple blind counting of events to determine the co-incidence of autophagy (LC3β punctuate), apoptosis (cleaved caspase-3), and unfolded protein response (GRP78) with HBV and HCV infection in hepatocytes. All statistical analyses were performed using SPSS software for Windows (Version 16 SPSS Inc, Chicago, IL, United States). P-values < 0.05 were considered statistically significant. Statistical analyses were performed with Mann-Whitney test to compare incidence rates for autophagy, apoptosis, and UPR in HBV- and HCV-infected cells and adjacent non-infected cells.

RESULTS

Our results showed that infection of hepatocytes with either HBV and HCV induces significant increase (P < 0.001) in apoptosis (cleavage of caspase-3), autophagy (LC3β punctate), and UPR (increase in GRP78 expression) in the HCV- and HBV-infected cells, as compared to non-infected cells of the same biopsy sections. Our tissue microarray immunohistochemical expression analysis of LC3β in HBV(Neg) and HBV(Pos) revealed that majority of HBV-infected hepatocytes display strong positive staining for LC3β. Interestingly, although XBP splicing in HBV-infected cells was significantly higher (P < 0.05), our analyses show a slight increase of XBP splicing was in HCV-infected cells (P > 0.05). Furthermore, our evaluation of patients with HBV and HCV infection based on stage and grade of the liver diseases revealed no correlation between these pathological findings and induction of apoptosis, autophagy, and UPR.

CONCLUSION

The results of this study indicate that HCV and HBV infection activates apoptosis, autophagy and UPR, but slightly differently by each virus. Further studies are warranted to elucidate the interconnections between these pathways in relation to pathology of HCV and HBV in the liver tissue.

Hepatic apoptotic markers are not predictors for the virological response to interferon-based therapy in chronic hepatitis C patients

INTRODUCTION

Chronic hepatitis C virus (HCV) infection is a major health problem worldwide. The majority of cases involving HCV infection develop into chronic hepatitis because of a failure to develop an effective immune response. Apoptosis of the hepatocytes plays a significant role in the pathogenesis of HCV infection: the interaction between the Fas antigen on hepatocytes and the Fas ligand on T cells corresponds to the main mechanism for hepatocyte damage. Interferon (IFN)-α has antiviral, immunoregulatory, and antiproliferative properties, and apoptosis seems to be a critical event in the action mechanisms of both IFNs. In this study, we aimed to detect any relationship between apoptotic markers in the liver and the response to the treatment.

MATERIALS AND METHODS

The study included 180 chronic HCV patients treated with IFN and ribavirin in four centers. Apoptotic markers (Fas, Fas ligand, Fas-associated death domain, caspases 3, 8, and 9, and in-situ apoptosis) were studied in the liver. The age, sex of the patients, response to therapy, ALT level, viral load, and genotype were recorded.

RESULTS

The results of the study showed that the histological activity index and fibrosis correlated with CD95 staining density, caspase-8 intensiveness, and portal and parenchymal Fas ligand scores. The apoptotic parameters of the responsive cases were not significantly different from those of the unresponsive cases.

CONCLUSION

The apoptotic parameters studied in liver tissue are associated with inflammation and fibrosis; however, these parameters may not predict response to treatment.

Disruption of Bcl-2 and Bcl-xL by viral proteins as a possible cause of cancer

The Bcl proteins play a critical role in apoptosis, as mutations in family members interfere with normal programmed cell death. Such events can cause cell transformation, potentially leading to cancer. Recent discoveries indicate that some viral proteins interfere with Bcl proteins either directly or indirectly; however, these data have not been systematically described. Some viruses encode proteins that reprogramme host cellular signalling pathways controlling cell differentiation, proliferation, genomic integrity, cell death, and immune system recognition. This review analyses and summarises the existing data and discusses how viral proteins interfere with normal pro- and anti-apoptotic functions of Bcl-2 and Bcl-xL. Particularly, this article focuses on how viral proteins, such as Herpesviruses, HTLV-1, HPV and HCV, block apoptosis and how accumulation of such interference predisposes cancer development. Finally, we discuss possible ways to prevent and treat cancers using a combination of traditional therapies and antiviral preparations that are effective against these viruses.

Serum apoptosis markers related to liver damage in chronic hepatitis C: sFas as a marker of advanced fibrosis in children and adults while M30 of severe steatosis only in children

Background

Liver biopsy represents the gold standard for evaluating damage and progression in patients with chronic hepatitis C (CHC); however, developing noninvasive tests that can predict liver injury represents a growing medical need. Considering that hepatocyte apoptosis plays a role in CHC pathogenesis; the aim of our study was to evaluate the presence of different apoptosis markers that correlate with liver injury in a cohort of pediatric and adult patients with CHC.

Methods

Liver biopsies and concomitant serum samples from 22 pediatric and 22 adult patients with CHC were analyzed. Histological parameters were evaluated. In serum samples soluble Fas (sFas), caspase activity and caspase-generated neoepitope of the CK-18 proteolytic fragment (M30) were measured.

Results

sFas was associated with fibrosis severity in pediatric (significant fibrosis p = 0.03, advanced fibrosis p = 0.01) and adult patients (advanced fibrosis p = 0.02). M30 levels were elevated in pediatric patients with severe steatosis (p = 0.01) while in adults no relation with any histological variable was observed. Caspase activity levels were higher in pediatric samples with significant fibrosis (p = 0.03) and they were associated with hepatitis severity (p = 0.04) in adult patients. The diagnostic accuracy evaluation demonstrated only a good performance for sFas to evaluate advanced fibrosis both in children (AUROC: 0.812) and adults (AUROC: 0.800) as well as for M30 to determine steatosis severity in children (AUROC: 0.833).

Conclusions

Serum sFas could be considered a possible marker of advanced fibrosis both in pediatric and adult patient with CHC as well as M30 might be a good predictor of steatosis severity in children.

p53 controls hepatitis C virus non-structural protein 5A-mediated downregulation of GADD45α expression via the NF-κB and PI3K-Akt pathways

Growth arrest and DNA-damage-inducible gene 45-α (GADD45α) protein has been shown to be a tumour suppressor and is implicated in cell-cycle arrest and suppression of cell growth. The hepatitis C virus (HCV) non-structural 5A (NS5A) protein plays an important role in cell survival and is linked to the development of hepatocellular carcinoma (HCC). However, the role of HCV NS5A in the development of HCC remains to be clarified. This study sought to determine whether GADD45α mediates HCV NS5A-induced cellular survival and to elucidate the molecular mechanism of GADD45α expression regulated by HCV NS5A. It was found that HCV NS5A downregulated GADD45α expression at the transcriptional level by decreasing promoter activity, mRNA transcription and protein levels. Knockdown of p53 resulted in a similar decrease in GADD45α expression to that caused by HCV NS5A, whilst overexpression of p53 reversed the HCV NS5A-mediated downregulation of GADD45α. HCV NS5A repressed p53 expression, which was followed by a subsequent decrease in GADD45α expression. Further evidence was provided showing that HCV NS5A led to increases of phosphorylated nuclear factor-κB and Akt levels. Inhibition of these pathways using pharmacological inhibitors or specific small interfering RNAs rescued HCV NS5A-mediated downregulation of p53 and GADD45α. It was also found that HCV NS5A protein and depletion of GADD45α increased cell growth, whereas ectopic expression of GADD45α eliminated HCV NS5A-induced cell proliferation. These results indicated that HCV NS5A downregulates GADD45α expression and subsequently triggers cellular proliferation. These findings provide new insights suggesting that HCV NS5A could contribute to the occurrence of HCV-related HCC.

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.