Interaction Of Hepatitis Research Articles

Hepatitis B virus suppresses complement C9 synthesis by limiting the availability of transcription factor USF-1 and inhibits formation of membrane attack complex: implications in disease pathogenesis

BackgroundThe complement system functions primarily as a first-line host defense against invading microbes, including viruses. However, the interaction of Hepatitis B virus (HBV) with the complement-components during chronic HBV infection remains largely unknown. We investigated the mechanism by which HBV inhibits the formation of cytolytic complement membrane-attack complex (MAC) and studied its impact on MAC-mediated microbicidal activity and disease pathogenesis.MethodsBlood/liver tissues were collected from chronically HBV-infected patients and controls. HepG2hNTCP cells were infected with HBV particles and Huh7 cells were transfected with full-length linear HBV-monomer or plasmids containing different HBV-ORFs and expression of complement components or other host genes were evaluated. Additionally, ELISA, Real-time PCR, Western blot, bioinformatics analysis, gene overexpression/knock-down, mutagenesis, chromatin immunoprecipitation, epigenetic studies, immunofluorescence, and quantification of serum HBV-DNA, bacterial-DNA and endotoxin were performed.ResultsAmong the MAC components (C5b-C9), significant reduction was noted in the expression of C9, the major constituent of MAC, in HBV-infected HepG2hNTCP cells and in Huh7 cells transfected with full-length HBV as well as HBX. C9 level was also marked low in sera/liver of chronic hepatitis B (CHB) and Immune-tolerant (IT) patients than inactive carriers and healthy controls. HBX strongly repressed C9-promoter activity in Huh7 cells but CpG-island was not detected in C9-promoter. We identified USF-1 as the key transcription factor that drives C9 expression and demonstrated that HBX-induced hypermethylation of USF-1-promoter is the leading cause of USF-1 downregulation that in turn diminished C9 transcription. Reduced MAC formation and impaired lysis of HBV-transfected Huh7 and bacterial cells were observed following incubation of these cells with C9-deficient CHB sera but was reversed upon C9 supplementation. Significant inverse correlation was noted between C9 concentration and HBV-DNA, bacterial-DNA and endotoxin content in HBV-infected patients. One-year Tenofovir therapy resulted in improvement in C9 level and decline in viral/bacterial/endotoxin load in CHB patients.ConclusionCollectively, HBX suppressed C9 transcription by restricting the availability of USF-1 through hypermethylation of USF-1-promoter and consequently hinder the formation and lytic functions of MAC. Early therapy is needed for both CHB and IT to normalize the aberrant complement profile and contain viral and bacterial infection and limit disease progression.

FRI393 - Polypharmacy and prevalence of multi drug-drug interactions in hepatitis C patients treated with pangenotypic direct acting antivirals: an analysis from three European countries

FRI393 - Polypharmacy and prevalence of multi drug-drug interactions in hepatitis C patients treated with pangenotypic direct acting antivirals: an analysis from three European countries

Interaction of Hepatitis B Virus X Protein with the Pregnane X Receptor Enhances the Synergistic Effects of Aflatoxin B1 and Hepatitis B Virus on Promoting Hepatocarcinogenesis

Background and AimsHepatitis B virus (HBV) infection has been found to increase hepatocellular sensitivity to carcinogenic xenobiotics, by unknown mechanisms, in the generation of hepatocellular carcinoma. The pregnane X receptor (PXR) is a key regulator of the body’s defense against xenobiotics, including xenobiotic carcinogens and clinical drugs. In this study, we aimed to investigate the molecular mechanisms of HBV X protein (HBx)-PXR signaling in the synergistic effects of chemical carcinogens in HBV-associated hepatocarcinogenesis.MethodsThe expression profile of PXR-cytochrome p450 3A4 (CYP3A4) signaling was determined by PCR, western blotting, and tissue microarray. Cell viability and aflatoxin B1 (AFB1) cytotoxicity were measured using the cell counting kit-8 assay. Target gene expression was evaluated using transient transfection and real time-PCR. The genotoxicity of AFB1 was assessed in newborn mice with a single dose of AFB1.ResultsHBx enhanced the hepatotoxicity of AFB1 by activating CYP3A4 and reducing glutathione S-transferase Mu 1 (GSTM1) in cell lines. Activation of PXR by pregnenolone 16α-carbonitrile increased AFB1-induced liver tumor incidence by up-regulating oncogenic KRAS to enhance interleukin (IL)-11:IL-11 receptor subunit alpha-1 (IL11RA-1)-mediated inflammation in an HBx transgenic model.ConclusionsOur finding regarding AFB1 toxicity enhancement by an HBx-PXR-CYP3A4/ GSTM1-KRAS-IL11:IL11RA signaling axis provides a rational explanation for the synergistic effects of chemical carcinogens in HBV infection-associated hepatocarcinogenesis.

Hepatitis B virus exploits C-type lectin receptors to hijack cDC1s, cDC2s and pDCs.

ObjectivesC‐type lectin receptors (CLRs) are key receptors used by DCs to orchestrate responses to pathogens. During infections, the glycan–lectin interactions shape the virus–host interplay and viruses can subvert the function of CLRs to escape antiviral immunity. Recognition of virus/viral components and uptake by CLRs together with subsequent signalling cascades are crucial in initiating and shaping antiviral immunity, and decisive in the outcome of infection. Yet, the interaction of hepatitis B virus (HBV) with CLRs remains largely unknown. As HBV hijacks DC subsets and viral antigens harbour glycan motifs, we hypothesised that HBV may subvert DCs through CLR binding.MethodsWe investigated here the pattern of CLR expression on BDCA1+ cDC2s, BDCA2+ pDCs and BDCA3+ cDC1s from both blood and liver of HBV‐infected patients and explored the ability of HBsAg to bind DC subsets through specific CLRs.ResultsWe highlighted for the first time that the CLR repertoire of circulating and intrahepatic cDC2s, cDC1s and pDCs was perturbed in patients with chronic HBV infection and that some CLR expression levels correlated with plasma HBsAg and HBV DNA levels. We also identified candidate CLR responsible for HBsAg binding to cDCs (CD367/DCIR/CLEC4A, CD32/FcɣRIIA) and pDCs (CD369/DECTIN1/CLEC7A, CD336/NKp44) and demonstrated that HBsAg inhibited DC functions in a CLR‐ and glycosylation‐dependent manner.ConclusionHBV may exploit CLR pathways to hijack DC subsets and escape from immune control. Such advances bring insights into the mechanisms by which HBV subverts immunity and pave the way for developing innovative therapeutic strategies to restore an efficient immune control of the infection by manipulating the viral glycan–lectin axis.

Chronic hepatitis delta: A state-of-the-art review and new therapies.

Chronic delta hepatitis is the most severe form of viral hepatitis affecting nearly 65 million people worldwide. Individuals with this devastating illness are at higher risk for developing cirrhosis and hepatocellular carcinoma. Delta virus is a defective RNA virus that requires hepatitis B surface antigen for propagation in humans. Infection can occur in the form of a co-infection with hepatitis B, which can be self-limiting, vs superinfection in a patient with established hepatitis B infection, which often leads to chronicity in majority of cases. Current noninvasive tools to assess for advanced liver disease have limited utility in delta hepatitis. Guidelines recommend treatment with pegylated interferon, but this is limited to patients with compensated disease and is efficacious in about 30% of those treated. Due to limited treatment options, novel agents are being investigated and include entry, assembly and export inhibitors of viral particles in addition to stimulators of the host immune response. Future clinical trials should take into consideration the interaction of hepatitis B and hepatitis D as suppression of one virus can lead to the activation of the other. Also, surrogate markers of treatment efficacy have been proposed.

Interaction of hepatitis C virus with the immune system in pregnant women with chronic hepatitis C

Interaction of hepatitis C virus with the immune system in pregnant women with chronic hepatitis C

A Coiled‐Coil Domain Containing 50 Splice Variant Is Modulated by Serine/Arginine‐Rich Splicing Factor 3 and Promotes Hepatocellular Carcinoma in Mice by the Ras Signaling Pathway

Deregulation of alternative splicing contributes to the malignant progression of cancer. Little is known about the significant alternative splicing events in hepatocellular carcinoma (HCC). High-throughput sequencing revealed that coiled-coil domain containing 50 (CCDC50) pre-mRNA is aberrantly spliced in 50% of our HCC cases. A BaseScope assay was performed to examine the expression of CCDC50S (a truncated oncogenic splice variant) in HCC tissues. Compared with benign liver tumors and several other types of solid tumors, CCDC50S mRNA was up-regulated in HCC, with a diagnostic potential (sensitivity, 0.711; specificity, 0.793). High expression of CCDC50S mRNA in HCC was significantly correlated with poor tumor differentiation, advanced tumor node metastasis (TNM) stage, and unfavorable prognosis. Overexpression of CCDC50S exerted tumorigenic activities that promoted HCC growth and metastasis by activation of Ras/forkhead box protein O4 (Foxo4) signaling. Either suppression of mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) phosphorylation or overexpression of Foxo4 markedly attenuated CCDC50S-mediated phenotypes. Furthermore, serine- and arginine-rich splicing factor 3 (SRSF3) directly bound to CCDC50S mRNA to maintain its stability in the cytoplasm. The cytosolic retention of SRSF3 was mediated by the interaction of hepatitis B virus-encoded X protein (HBx) and 14-3-3β. Ectopic HBx expression induced expression of cytosolic SRSF3 and CCDC50S. Conclusion: Our study provided compelling evidence that up-regulation of CCDC50S was modulated by HBx/SRSF3/14-3-3β complex and enhanced oncogenic progression of HCC through the Ras/Foxo4 signaling pathway. These data suggest that CCDC50S may serve as a diagnostic and prognostic biomarker and probably a promising therapeutic target in HCC.

Identification of Protein-protein Interaction of Hepatitis B Virus X Protein and Tab1 in Vivo and in Vitro

Identification of Protein-protein Interaction of Hepatitis B Virus X Protein and Tab1 in Vivo and in Vitro

Drug-drug interactions in hepatitis C virus treatment: Do they really matter?

Drug-drug interactions in hepatitis C virus treatment: Do they really matter?

T Cells Infiltrating Diseased Liver Express Ligands for the NKG2D Stress Surveillance System.

NK cells, which are highly enriched in the liver, are potent regulators of antiviral T cells and immunopathology in persistent viral infection. We investigated the role of the NKG2D axis in T cell/NK cell interactions in hepatitis B. Activated and hepatitis B virus (HBV)–specific T cells, particularly the CD4 fraction, expressed NKG2D ligands (NKG2DL), which were not found on T cells from healthy controls (p < 0.001). NKG2DL-expressing T cells were strikingly enriched within HBV-infected livers compared with the periphery or to healthy livers (p < 0.001). NKG2D+NK cells were also increased and preferentially activated in the HBV-infected liver (p < 0.001), in direct proportion to the percentage of MICA/B-expressing CD4 T cells colocated within freshly isolated liver tissue (p < 0.001). This suggests that NKG2DL induced on T cells within a diseased organ can calibrate NKG2D-dependent activation of local NK cells; furthermore, NKG2D blockade could rescue HBV-specific and MICA/B-expressing T cells from HBV-infected livers. To our knowledge, this is the first ex vivo demonstration that non-virally infected human T cells can express NKG2DL, with implications for stress surveillance by the large number of NKG2D-expressing NK cells sequestered in the liver.

Corrigendum: Conserved RNA secondary structures and long-range interactions in hepatitis C viruses.

In the Discussion section (first paragraph, third sentence) on page 105 of the above-noted article, the sentence “The RNA architectures identified in our study were not predicted by in silico approaches (Pervouchine 2014), nor were they detected using recent high-throughput RNA structure sequencing techniques (Daines et al. 2011; Li et al. 2012)” was not clear and should instead read as follows: “The RNA bidirectional structural architectures identified in our study were not detected using recent high-throughput RNA structure sequencing techniques (Daines et al. 2011; Li et al. 2012), nor were they discovered by in silico approaches, although stem II of the Drosophila srp pre-mRNA was predicted (Raker et al. 2009; Pervouchine 2014).” Accordingly, the following reference should be included in the References section: Raker VA, Mironov AA, Gelfand MS, Pervouchine DD. 2009. Modulation of alternative splicing by long-range RNA structures in Drosophila. Nucleic Acids Res 37: 4533–4544. The authors apologize for any confusion this may have caused. This article has been corrected in both the PDF and full-text HTML files online.

Phosphorylation-Mediated Interaction of Hepatitis C Virus NS5A and the Cellular YB-1 Controls HCV Propagation and the Early Stage of Viral RNA Replication

About 130-150 million individuals worldwide are chronically infected by hepatitis C virus (HCV); HCV infection has become a leading cause of liver cirrhosis and hepatocellular carcinoma. The HCV life cycle relies on the cooperation of specific viral proteins and various cellular factors. The cellular protein Y-box binding protein 1 (YB-1) has recently been identified as a HCV host cofactor; however, its mechanism has not been fully characterized. The HCV nonstructural protein NS5A plays critical roles in almost every stage of HCV propagation, and has been proposed to control the switch between the defined stages of the HCV life cycle. Moreover, NS5A has recently emerged as a target for the development of novel anti-HCV drugs. Our studies have found that YB-1 not only interacts with NS5A, but also protects NS5A from degradation. Furthermore, both the NS5A/YB-1 interaction and the NS5A-stabilizing activity of YB-1 are dependent on the phosphorylation of YB-1 at serine 102 (S102). Interestingly, the YB-1 S102 site has previously been reported to be phosphorylated by Akt, which is in turn activated by HCV infection. Our study also reveals that DDX3, an YB-1-interacting partner, is another NS5A-binding protein, which plays a different role than YB-1 in HCV RNA replication and infectious virus production. Taken together, the elucidation of YB-1 participation in the HCV life cycle has led to a proposed mechanism of efficient virus propagation via coordination of the different stages of the viral life cycle through controlling stage-wise switches in the viral life cycle. Our finding also provides a novel niche for designing strategies for the development of new anti-HCV drugs by blocking specific virus-host interactions.

Interaction of hepatitis B virus X protein with PARP1 results in inhibition of DNA repair in hepatocellular carcinoma.

Hepatitis B virus X protein (HBx) contributes to the development of hepatocellular carcinoma (HCC), probably by regulating activities of many host or viral proteins through protein-protein interactions. In this study, we identified poly(ADP-ribose) polymerase (PARP1), a crucial factor in DNA repair, as an HBx-interacting protein using a proteomics approach. Coimmunoprecipitation and proximity ligation assays confirmed the binding and colocalization of HBx and PARP1 in the nucleus. The carboxyl-terminus of HBx protein bound to the catalytic domain of PARP1, and this binding reduced the enzymatic activity of PARP1 in both in vitro and in vivo assays. HBx interrupted the binding of PARP1 to Sirt6, which catalyzes the mono-ADP-ribosylation required for DNA repair. Consistently, overexpression of HBx inhibited the clearance of γH2AX DNA repair foci generated under oxidative stress in Chang liver cells. Recruitment of the DNA repair complex to the site-specific double-strand breaks was inhibited in the presence of HBx, when measured by laser microirradiation assay and damage-specific chromatin immunoprecipitation assays. Consequently, HBx increased signs of DNA damage such as accumulation of 8-hydroxy-2'-deoxyguanosine and comet formation, which were reversed by overexpression of PARP1 and/or Sirt6. Finally, the interaction between PARP1 and Sirt6 was markedly lower in the livers of HBx-transgenic mice and specimens obtained from HCC patients to compare with the corresponding control. Our data suggest that the physical interaction of HBx and PARP1 accelerates DNA damage by inhibiting recruitment of the DNA repair complex to the damaged DNA sites, which may lead to the onset of hepatocarcinogenesis.

Host-virus interactions in hepatitis B and hepatitis C infection.

Hepatitis B virus (HBV) and hepatitis C virus (HCV) are among the most endemic pathogens worldwide, with more than 500 million people globally currently infected with these viruses. These pathogens can cause acute and chronic hepatitis that progress to liver cirrhosis or hepatocellular carcinoma. Both viruses utilize multifaceted strategies to evade the host surveillance system and fall below the immunological radar. HBV has developed specific strategies to evade recognition by the innate immune system and is acknowledged to be a stealth virus. However, extensive research has revealed that HBV is recognized by dendritic cells (DCs) and natural killer (NK) cells. Indoleamine-2, 3-dioxygenase is an enforcer of sequential immune reactions in acute hepatitis B, and this molecule has been shown to be induced by the interaction of HBV-infected hepatocytes, DCs, and NK cells. The interleukin-28B genotype has been reported to influence HCV eradication either therapeutically or spontaneously, but the biological function of its gene product, a type-III interferon (IFN-λ3), remains to be elucidated. Human BDCA3(+)DCs have also been shown to be a potent producer of IFN-λ3 in HCV infection, suggesting the possibility that BDCA3(+)DCs could play a key role in developing therapeutic HCV vaccine. Here we review the current state of research on immune responses against HBV and HCV infection, with a specific focus on innate immunity. A comprehensive study based on clinical samples is urgently needed to improve our understanding of the immune mechanisms associated with viral control and thus to develop novel immune modulatory therapies to cure chronic HBV and HCV infection.

A THEORETICAL ASSESSMENT OF THE EFFECTS OF DISTRIBUTED DELAY ON THE TRANSMISSION DYNAMICS OF HEPATITIS B

In this paper, we investigate the global dynamics of a system of delay differential equations which describes the interaction of hepatitis B virus (HBV) with both liver and blood cells. The model has two distributed time delays describing the time needed for infection of cell and virus replication. We also include the efficiency of drug therapy in inhibiting viral production and the efficiency of drug therapy in blocking new infection. We compute the basic reproduction number and find that increasing delays will decrease the value of the basic reproduction number. We study the sensitivity analysis on the key parameters that drive the disease dynamics in order to determine their relative importance to disease transmission and prevalence. Our analysis reveals that the model exhibits the phenomenon of backward bifurcation (where a stable disease-free equilibrium (DFE) co-exists with a stable endemic equilibrium when the basic reproduction number is less than unity). Numerical simulations are presented to evaluate the impact of time-delays on the prevalence of the disease.

Molecular modeling and multispectroscopic studies of the interaction of hepatitis B drug, adefovir dipivoxil with human serum albumin

The interaction of hepatitis B drug, adefovir dipivoxil with human serum albumin (HSA) was studied by using UV–vis, fluorometric, circular dichroism (CD) and molecular docking techniques. The results indicated that the binding of the drug to HSA caused fluorescence quenching through static quenching mechanism with binding constant of 1.3×103M−1. The thermodynamic parameters indicated that the hydrophobic force contacts are the major forces in the stability of protein-drug complex (ΔH>0 and ΔS>0). The displacement experiments using the site probes viz., warfarin and ibuprofen showed that adefovir dipivoxil could bind to the site III of HSA. The results of CD and UV–vis spectroscopy indicated that the binding of the drug induced some conformational changes in HSA. Furthermore, the study of molecular docking also confirmed binding of adefovir dipivoxil to the site III of HSA by hydrophobic interaction.

Interactions of Hepatitis B Virus Infection with Nonalcoholic Fatty Liver Disease: Possible Mechanisms and Clinical Impact.

Hepatitis B virus (HBV) infection is a major etiology of chronic liver disease worldwide. In the past decade, nonalcoholic fatty liver disease (NAFLD) has emerged as a common liver disorder in general population. Accordingly, the patient number of chronic hepatitis B (CHB) concomitant with NAFLD grows rapidly. The present article reviewed the recent studies aiming to explore the relationship between CHB and NAFLD from different aspects, including the relevant pathogenesis of CHB and NAFLD, the intracellular molecular mechanisms overlaying HBV infection and hepatic steatosis, and the observational studies with animal models and clinical cohorts for analyzing the coincidence of the two diseases. It is concluded that although numerous cross-links have been suggested between the molecular pathways in HBV infection and NAFLD pathogenesis, regarding whether HBV infection can substantially interfere with the occurrence of NAFLD or vice versa in the patients, there is still far from a conclusive agreement.

Conserved RNA secondary structures and long-range interactions in hepatitis C viruses.

Hepatitis C virus (HCV) is a hepatotropic virus with a plus-strand RNA genome of ∼9.600 nt. Due to error-prone replication by its RNA-dependent RNA polymerase (RdRp) residing in nonstructural protein 5B (NS5B), HCV isolates are grouped into seven genotypes with several subtypes. By using whole-genome sequences of 106 HCV isolates and secondary structure alignments of the plus-strand genome and its minus-strand replication intermediate, we established refined secondary structures of the 5′ untranslated region (UTR), the cis-acting replication element (CRE) in NS5B, and the 3′ UTR. We propose an alternative structure in the 5′ UTR, conserved secondary structures of 5B stem–loop (SL)1 and 5BSL2, and four possible structures of the X-tail at the very 3′ end of the HCV genome. We predict several previously unknown long-range interactions, most importantly a possible circularization interaction between distinct elements in the 5′ and 3′ UTR, reminiscent of the cyclization elements of the related flaviviruses. Based on analogy to these viruses, we propose that the 5′–3′ UTR base-pairing in the HCV genome might play an important role in viral RNA replication. These results may have important implications for our understanding of the nature of the cis-acting RNA elements in the HCV genome and their possible role in regulating the mutually exclusive processes of viral RNA translation and replication.

Kupffer cells interact with hepatitis B surface antigen in vivo and in vitro, leading to proinflammatory cytokine production and natural killer cell function.

Based on their localization, Kupffer cells (KCs) likely interact with hepatitis B virus (HBV). However, the role of KCs in inducing immunity toward HBV is poorly understood. Therefore, the interaction of hepatitis B surface antigen (HBsAg) and KCs, and possible functional consequences, were assessed. KCs in liver tissue from patients with chronic HBV were analyzed for presence of HBsAg and their phenotype, and compared with KCs in control liver tissue. Liver graft perfusate-derived KCs and in vitro-generated monocyte-derived macrophages were investigated for functional interaction with patient-derived HBsAg. Intrahepatic KCs were HBsAg positive and more activated than those from control livers. KCs internalized HBsAg in vitro, which did not change their phenotype, but strongly induced proinflammatory cytokine production. Additionally, monocyte-derived macrophages also interacted with HBsAg, leading to activation and cytokine production. Furthermore, HBsAg-exposed macrophages and KC activated natural killer (NK) cells, resulting in increased CD69 expression and interferon-γ production. KCs directly interact with HBsAg in vivo and in vitro. HBsAg-induced cytokine production by KCs and monocyte-derived macrophages and subsequent NK cell activation may be an early event in viral containment and may support induction of HBV-specific immunity upon HBV infection, but may also contribute to liver pathology.

Interaction of Hepatitis C Viral Proteins with Cellular Oncoproteins in the Induction of Liver Cancer

Hepatitis C virus infection is a major health problem all over the world. A large proportion of patients infected by HCV develop liver cirrhosis or cancer. However, the mechanism(s) remain to be elucidated. Since HCV does not carry any known oncogene, it is thought that interaction between virally encoded proteins and host proteins is responsible for carcinogenesis. Many crucial interactions between HCV-encoded proteins and host proteins have been reported. In this review we focus on the interaction of viral proteins with important regulators of cell cycle—oncoproteins YB-1, p53, and cyclin D1—which play a major role in cell proliferation, apoptosis, DNA repair, and genomic stability. Genetic variants of HCV accumulate in patients and alter these interactions of host cell proteins. It is a battle between the virus and host and the final outcome depends on the winner; if the host succeeds in clearing the virus the patient may not develop serious liver diseases. On the other hand, if the virus dominates by evolving quasispecies which code for altered proteins that interact differently with host proteins, or induce mutations in host protooncogenes, then the patient may develop liver cirrhosis and/or liver cancer.