Tumor necrosis factor activates a conserved innate antiviral response to hepatitis B virus that destabilizes nucleocapsids and reduces nuclear viral DNA

Tripartite motif-containing protein 21 is involved in IFN-γ-induced suppression of hepatitis B virus by regulating hepatocyte nuclear factors

The antiviral role of the tripartite motif-containing (TRIM) protein family , a member of the E3-ubiquitin ligase family, has recently been actively studied. Hepatitis B virus (HBV) infection is a major contributor to liver diseases; however, the host factors regulated by cytokine-inducible TRIM21 to suppress HBV remain unclear. In this study, we showed the antiviral efficacy of TRIM21 against HBV in hepatoma cell lines, primary human hepatocytes isolated from patient liver tissues, and mouse model. Using TRIM21 knock-out cells, we confirmed that the antiviral effects of interferon-gamma, which suppress HBV replication, are diminished when TRIM21 is deficient. Northern blot analysis confirmed a reduction of HBV RNA levels by TRIM21. Using Luciferase reporter assay, we also discovered that TRIM21 decreases the activity of HBV enhancers, which play a crucial role in covalently closed circular DNA transcription. The participation of the RING domain and PRY-SPRY domain in the anti-HBV effect of TRIM21 was demonstrated through experiments using deletion mutants. We identified a novel interaction between TRIM21 and hepatocyte nuclear factor 4α (HNF4α) through co-immunoprecipitation assay. More specifically, ubiquitination assay revealed that TRIM21 promotes ubiquitin-mediated proteasomal degradation of HNF4α. HNF1α transcription is down-regulated as a result of the degradation of HNF4α, an activator for the HNF1α promoter. Therefore, the reduction of key HBV enhancer activators, HNF4α and HNF1α, by TRIM21 resulted in a decline in HBV transcription, ultimately leading to the inhibition of HBV replication.IMPORTANCEDespite extensive research efforts, a definitive cure for chronic hepatitis B remains elusive, emphasizing the persistent importance of this viral infection as a substantial public health concern. Although the risks associated with hepatitis B virus (HBV) infection are well known, host factors capable of suppressing HBV are largely uncharacterized. This study elucidates that tripartite motif-containing protein 21 (TRIM21) suppresses HBV transcription and consequently inhibits HBV replication by downregulating the hepatocyte nuclear factors, which are host factors associated with the HBV enhancers. Our findings demonstrate a novel anti-HBV mechanism of TRIM21 in interferon-gamma-induced anti-HBV activity. These findings may contribute to new strategies to block HBV.

Traditional Chinese medicine invigorating the spleen and kidney promotes HBsAg seroclearance in the mouse model

Traditional Chinese medicine (TCM) is often used as an adjuvant or alternative therapy for abnormal liver biochemistry or liver fibrosis associated with chronic hepatitis B (CHB). However, the role of TCM in HBsAg seroclearance remains unclear. We aimed at exploring the role and possible mechanisms of TCM in HBsAg seroclearance. Fifteen widely used TCM granules invigorating the spleen and kidneys were screened. C57BL/6J mice were administered daily with TCM granules by gavage for 1 week. The effect of TCM on the M1 polarization of macrophages was measured using a CD86 assay. According to the principles of formulating prescriptions, three single TCM with the most noticeable effect on M1 polarization, accompanied by two other TCM granules, were used to develop a TCM formula. The hepatitis B virus-expressing mouse model was constructed by hydrodynamic injection of the pAAV/HBV1.2 plasmid. Hepatitis B virus-expressing mice were gavaged daily with phosphate-buffered saline (PBS), TCM formula, or Codonopsis Radix, for 1 week. HBsAg, HBeAg, and hepatitis B virus DNA levels were measured. In addition, gut microbiota was profiled using 16S rDNA sequencing. Several TCM granules showed significant effects on M1 polarization. The TCM formula accelerated HBsAg seroclearance compared with the Codonopsis Radix and PBS groups. Intrahepatic M1 polarization, as indicated by flow cytometry and immunohistochemistry, was induced in the TCM formula and Codonopsis Radix groups. The abundance of Alloprevotella significantly increased in the TCM formula and Codonopsis Radix groups. These results demonstrate that the TCM formula for invigorating the spleen and kidney can accelerate HBsAg seroclearance. This effect can be attributed, at least in part, to M1 polarization of intrahepatic macrophages.

Alpha-kinase 1 (ALPK1) agonist DF-006 demonstrates potent efficacy in mouse and primary human hepatocyte (PHH) models of hepatitis B

BACKGROUND AND AIMS

In the treatment of chronic hepatitis B (CHB) infection, stimulation of innate immunity may lead to hepatitis B virus (HBV) cure. Alpha-kinase 1 (ALPK1) is a pattern recognition receptor (PRR) that activates the NF-κB pathway and stimulates innate immunity. Here we characterized the preclinical anti-HBV efficacy of DF-006, an orally active agonist of ALPK1 currently in clinical development for CHB.

APPROACH AND RESULTS

In adeno-associated virus (AAV)-HBV mouse models and primary human hepatocytes (PHHs) infected with HBV, we evaluated the antiviral efficacy of DF-006. In the mouse models, DF-006 rapidly reduced serum HBV DNA, hepatitis B surface antigen, and hepatitis B e antigen levels using doses as low as 0.08 μg/kg, 1 μg/kg, and 5 μg/kg, respectively. DF-006 in combination with the HBV nucleoside reverse transcriptase inhibitor, entecavir, further reduced HBV DNA. Antiviral efficacy in mice was associated with an increase in immune cell infiltration and decrease of hepatitis B core antigen, encapsidated pregenomic RNA, and covalently closed circular DNA in liver. At subnanomolar concentrations, DF-006 also showed anti-HBV efficacy in PHH with significant reductions of HBV DNA. Following dosing with DF-006, there was upregulation of NF-κB-targeted genes that are involved in innate immunity.

CONCLUSION

DF-006 was efficacious in mouse and PHH models of HBV without any indications of overt toxicity. In mice, DF-006 localized primarily to the liver where it potently activated innate immunity. The transcriptional response in mouse liver provides insights into mechanisms that mediate anti-HBV efficacy by DF-006.

Network-based pharmacology and molecular docking exploring the "Bupleuri Radix-Scutellariae Radix" mechanism of action in the viral hepatitis B treatment

Viral hepatitis B is caused by the hepatitis B virus, which is characterized by liver lesions. Bupleuri Radix and Scutellariae Radix are the main traditional medicine pairs with remarkable efficacy in hepatitis B. However, their molecular mechanisms are incompletely understood. The main active components of Bupleuri Radix and Scutellariae Radix, as well as therapeutic targets for the treatment of hepatitis B, were identified through network pharmacology techniques. We identified viral hepatitis B targets using the GeneCards, online mendelian inheritance in man, and therapeutic target databases. We discovered the active components of Bupleuri Radix and Scutellariae Radix as well as therapeutic targets using the encyclopedia of traditional Chinese medicine, HERB, traditional Chinese medicine systems pharmacology database, and a bioinformatics analysis tool for molecular mechanism of traditional Chinese medicine databases. VENNY obtained the intersections. Cytoscape and STRING were used to create the "active ingredient-potential target" network and protein interaction network. The DAVID database was used to enrich GO and KEGG pathways. The results were confirmed using the molecular docking method. There were 1827 viral hepatitis B targets, and 37 active ingredients for Bupleuri and Scutellariae Radix, with the main components being quercetin, wogonin, baicalein, and kaempferol. Tumor necrosis factor (TNF), mitogen-activated protein kinase 3 (MAPK3), interleukin-6 (IL-6), vascular endothelial growth factor A, cysteinyl aspartate specific proteinase 3, transcription factor AP-1 (JUN), RAC-alpha serine/threonine-protein kinase, and cellular tumor antigen p53 are among the 78 common targets of Bupleuri Radix and Scutellariae Radix intervention in viral hepatitis B. KEGG enrichment resulted in 107 pathways, including cancer, hepatitis B, and TNF signaling pathways. According to the molecular docking technique, quercetin, wogonin, baicalein, and kaempferol had strong binding activities with TNF, MAPK3, and IL-6. In this study, we initially identified various molecular targets and multiple pathways involved in hepatitis B treatment with Bupleuri Radix and Scutellariae Radix.

TNF in the liver: targeting a central player in inflammation

Tumour necrosis factor-α (TNF) is a multifunctional cytokine. First recognized as an endogenous soluble factor that induces necrosis of solid tumours, TNF became increasingly important as pro-inflammatory cytokine being involved in the immunopathogenesis of several autoimmune diseases. In the liver, TNF induces numerous biological responses such as hepatocyte apoptosis and necroptosis, liver inflammation and regeneration, and autoimmunity, but also progression to hepatocellular carcinoma. Considering these multiple functions of TNF in the liver, we propose anti-TNF therapies that specifically target TNF signalling at the level of its specific receptors.

A pilot study on some critical immune elements in HBV infection: evidence of Alpha-1 Antitrypsin as an immunological biomarker

Aim

This study is an attempt to screen the key immune elements that participate during HBV infection and the related pathways that are modulated.

Background

The pathogenesis of Hepatitis B virus and the corresponding clinical manifestations in the host are primarily immune-mediated.

Methods

This study utilizes a PCR array to screen immune-related genes that are differentially expressed in the presence of the virus in HBV replicating HepG2.2.15 cells as compared to control HepG2 cells. The significantly up-regulated genes were subjected to bioinformatic analysis utilizing GSEA and STRING. Additionally, ELISA was used to corroborate the levels of Alpha 1 antitrypsin (AAT) from patients' sera.

Results

The expressions of 31% of the studied genes were significantly up-regulated (> 2-fold, p<0.05) in HepG2.2.15 cells compared to controls, and this included the SERPINA1, FN1, IL1R2, LBP, LY96, LYZ and PROC genes. When they were clustered based on biological processes, signaling pathways, and disease progression, the genes related to biotic stimulus, complement-coagulation cascades, and fibrosis, respectively, showed the highest (p<0.05) enrichment. Analysis of patients' sera by ELISA revealed that the serum AAT (SERPINA1) levels were significantly higher in asymptomatic carriers and in patients with chronic liver disease than in controls (p<0.05). Moreover, SERPINA1 levels were also positively correlated with the levels of serum ALT (r=0.4495, p<0.05) among HBV infected patients.

Conclusion

The current study highlights the key immune elements and pathways that are modulated during HBV infection and proposes the possible use of AAT as a non-invasive immunological biomarker to follow the progression of liver disease.

Prevalence of Hepatitis B Virus Markers in Patients with Autoimmune Inflammatory Rheumatic Diseases in Italy

Chronic hepatitis B virus (HBV) infection may be reactivated by immunosuppressive drugs in patients with autoimmune inflammatory rheumatic diseases. This study evaluates HBV serum markers' prevalence in rheumatic outpatients belonging to Spondyloarthritis, Chronic Arthritis and Connective Tissue Disease diagnostic groups in Italy. The study enrolled 302 subjects, sex ratio (M/F) 0.6, mean age ± standard deviation 57 ± 15 years, 167 (55%) of whom were candidates for immunosuppressive therapy. The Spondyloarthritis group included 146 subjects, Chronic Arthritis 75 and Connective Tissue Disease 83 (two patients had two rheumatic diseases; thus, the sum is 304 instead of 302). Ten subjects (3%) reported previous anti-HBV vaccination and tested positive for anti-HBs alone with a titer still protective (>10 IU/mL). Among the remaining 292 subjects, the prevalence of positivity for HBsAg, isolated anti-HBc, anti-HBc/anti-HBs, and any HBV marker was 2%, 4%, 18%, and 24%, respectively. A total of 26/302 (9%) patients with γ-globulin levels ≤0.7 g/dL were more frequently (p = 0.03455) prescribed immunosuppressive therapy, suggesting a more severe rheumatic disease. A not negligible percentage of rheumatic patients in Italy are at potential risk of HBV reactivation related to immunosuppressive therapy. Before starting treatment, subjects should be tested for HBV markers. Those resulting positive should receive treatment or prophylaxis with Nucleos (t) ides analogue (NUCs) at high barrier of resistance, or pre-emptive therapy, according to the pattern of positive markers. HB vaccination is recommended for those who were never exposed to the virus.

Effects of tumor necrosis factor on viral replication and pulmonary inflammation during acute mouse adenovirus type 1 respiratory infection

CD8 T cells contribute to effective clearance of mouse adenovirus type 1 (MAV-1) and to virus-induced pulmonary inflammation. We characterized effects of a CD8 T cell effector, TNF, on MAV-1 pathogenesis. TNF inhibited MAV-1 replication in vitro. TNF deficiency or immunoneutralization had no effect on lung viral loads or viral gene expression in mice infected intranasally with MAV-1. Absence of TNF delayed virus-induced weight loss and reduced histological evidence of pulmonary inflammation, although concentrations of proinflammatory cytokines and chemokines in bronchoalveolar lavage fluid (BALF) were not significantly affected. BALF concentrations of IL-10 were greater in TNF-deficient mice compared to controls. Our data indicate that TNF is not essential for control of viral replication in vivo, but virus-induced TNF contributes to some aspects of immunopathology and disease. Redundant CD8 T cell effectors and other aspects of immune function are sufficient for antiviral and pro-inflammatory responses to acute MAV-1 respiratory infection.

Therapeutic strategies for hepatitis B virus infection: towards a cure

Chronic hepatitis B virus (HBV) infection is a common cause of liver disease globally, with a disproportionately high burden in South-East Asia. Vaccines and nucleoside or nucleotide drugs are available and reduce both new infection rates and the development of liver disease in HBV-positive persons who adhere to long-term suppressive treatment. Although there is still considerable value in optimizing access to virus-suppressing regimens, the scientific and medical communities have embarked on a concerted journey to identify new antiviral drugs and immune interventions aimed at curing infection. The mechanisms and drug targets being explored are diverse; however, the field universally recognizes the importance of addressing the persistence of episomal covalently closed circular DNA, the existence of integrated HBV DNA in the host genome and the large antigen load, particularly of hepatitis B surface antigen. Another major challenge is to reinvigorate the exhausted immune response within the liver microenvironment. Ultimately, combinations of new drugs will be required to cure infection. Here we critically review the recent literature that describes the rationale for curative therapies and the resulting compounds that are being tested in clinical trials for hepatitis B.

TNF-α polymorphisms affect persistence and progression of HBV infection

Background

Hepatitis B virus (HBV) infections are a major threat worldwide. Disease progression and outcome is diverse and depends on host genetic background. Recently, a high rate of HBV reactivation in individuals receiving tumor necrosis factor‐α (TNF‐α) antagonists showed the importance of this cytokine in HBV infection control. Here, we investigated the influence of TNF‐α promoter polymorphisms on susceptibility to chronic HBV infection (CHB), liver injury progression and outcomes.

Methods

A total of 231 patients with CHB constituted the study group and 100 healthy volunteers—the local control group. TNF‐α −1031T/C, −863C/A, −857C/T, −308G/A, and −238G/A were genotyped using MALDI‐TOF mass spectrometry.

Results

TNF‐α −1031C and −863A alleles were observed more frequently in CHB group than in healthy controls. Carriers of TNF‐α −1031C and −863A variant alleles had lower baseline levels of serum HBV DNA and lower liver necroinflammatory activity than dominant homozygotes. A −857CT genotype predisposed to higher necroinflammatory activity. No associations between TNF‐α variants and liver fibrosis were found.

Conclusion

This study indicates that TNF‐α −863A and −1031C alleles are associated with increased susceptibility to CHB in individuals from northern Poland. The same variants determine the course of CHB, lowering viremia and reducing necroinflammatory activity of the liver.

Immunotherapy for Chronic Hepatitis B Virus Infection

While new therapies for chronic hepatitis C virus infection have delivered remarkable cure rates, curative therapies for chronic hepatitis B virus (HBV) infection remain a distant goal. Although current direct antiviral therapies are very efficient in controlling viral replication and limiting the progression to cirrhosis, these treatments require lifelong administration due to the frequent viral rebound upon treatment cessation, and immune modulation with interferon is only effective in a subgroup of patients. Specific immunotherapies can offer the possibility of eliminating or at least stably maintaining low levels of HBV replication under the control of a functional host antiviral response. Here, we review the development of immune cell therapy for HBV, highlighting the potential antiviral efficiency and potential toxicities in different groups of chronically infected HBV patients. We also discuss the chronic hepatitis B patient populations that best benefit from therapeutic immune interventions.

B-Cell Lymphoma 6 (BCL6) Is a Host Restriction Factor That Can Suppress HBV Gene Expression and Modulate Immune Responses

Hepatitis B virus (HBV) infection causes acute and chronic liver inflammation. Recent studies have demonstrated that some viral antigens can suppress host innate and adaptive immunity, and thus lead to HBV liver persistency. However, the cellular factors that can help host cells to clear HBV during acute infection remain largely unknown. Here, we used HBV-cleared and HBV-persistent mouse models to seek for cellular factors that might participate in HBV clearance. HBV replicon DNA was delivered into the mouse liver by hydrodynamic injection. RNA-Seq analysis was conducted to identify immune-related genes that were differentially expressed in HBV-persistent and HBV-cleared mouse models. A cellular factor, B cell lymphoma 6 (BCL6), was found to be significantly upregulated in the liver of HBV-cleared mice upon HBV clearance. Co-expression of BCL6 and a persistent HBV clone rendered the clone largely cleared, implicating an important role of BCL6 in controlling HBV clearance. Mechanistic studies demonstrated that BCL6 functioned as a repressor, binding to and suppressing the activities of the four HBV promoters. Correspondingly, BCL6 expression significantly reduced the levels of HBV viral RNA, DNA, and proteins. BCL6 expression could be stimulated by inflammatory cytokines such as TNF-α; the BCL6 in turn synergized TNF-α signaling to produce large amounts of CXCL9 and CXCL10, leading to increased infiltrating immune cells and elevated cytokine levels in the liver. Thus, positive feedback loops on BCL6 expression and immune responses could be produced. Together, our results demonstrate that BCL6 is a novel host restriction factor that exerts both anti-HBV and immunomodulatory activities. Induction of BCL6 in the liver may ultimately assist host immune responses to clear HBV.

Clinical Implications of Hepatitis B Virus RNA and Covalently Closed Circular DNA in Monitoring Patients with Chronic Hepatitis B Today with a Gaze into the Future: The Field Is Unprepared for a Sterilizing Cure

. Chronic hepatitis B virus (HBV) infection has long remained a critical global health issue. Covalently closed circular DNA (cccDNA) is a persistent form of the HBV genome that maintains HBV chronicity. Decades of extensive research resulted in the two therapeutic options currently available: nucleot(s)ide analogs and interferon (IFN) therapy. A plethora of reliable markers to monitor HBV patients has been established, including the recently discovered encapsidated pregenomic RNA in serum, which can be used to determine treatment end-points and to predict the susceptibility of patients to IFN. Additionally, HBV RNA splice variants and cccDNA and its epigenetic modifications are associated with the clinical course and risks of hepatocellular carcinoma (HCC) and liver fibrosis. However, new antivirals, including CRISPR/Cas9, APOBEC-mediated degradation of cccDNA, and T-cell therapies aim at completely eliminating HBV, and it is clear that the diagnostic arsenal for defining the long-awaited sterilizing cure is missing. In this review, we discuss the currently available tools for detecting and measuring HBV RNAs and cccDNA, as well as the state-of-the-art in clinical implications of these markers, and debate needs and goals within the context of the sterilizing cure that is soon to come.

Intracellular interleukin-32γ mediates antiviral activity of cytokines against hepatitis B virus

Cytokines are involved in early host defense against pathogen infections. In particular, tumor necrosis factor (TNF) and interferon-gamma (IFN-γ) have critical functions in non-cytopathic elimination of hepatitis B virus (HBV) in hepatocytes. However, the molecular mechanisms and mediator molecules are largely unknown. Here we show that interleukin-32 (IL-32) is induced by TNF and IFN-γ in hepatocytes, and inhibits the replication of HBV by acting intracellularly to suppress HBV transcription and replication. The gamma isoform of IL-32 (IL-32γ) inhibits viral enhancer activities by downregulating liver-enriched transcription factors. Our data are validated in both an in vivo HBV mouse model and primary human hepatocytes. This study thus suggests that IL-32γ functions as intracellular effector in hepatocytes for suppressing HBV replication to implicate a possible mechanism of non-cytopathic viral clearance.

Cytokines such as TNF and IFN-γ are important for immunity against hepatitis B virus (HBV). Here the authors show that interleukin-32 gamma (IL-32γ) acts downstream of TNF and IFN-γ as an intracellular effector, and that IL-32γ negatively regulates host factors contributing to HBV transcription to promote HBV clearance.

Bushen recipe and its disassembled prescriptions inhibit inflammation of liver injury associated with Concanavalin A through Toll‑like receptor 3/9 signaling pathway

The aim of the present study was to explore the effect of Bushen recipe and its disassembled prescriptions on liver injury and chronic hepatitis B. Liver injury was induced in normal and hepatitis B virus (HBV)‑transgenic mice through injection of Concanavalin A, followed by treatment with Bushen recipe and its disassembled prescriptions including the Bushen‑yang, the Bushen‑yin and the QingHua groups as well as the GanYanLing group (positive control). Subsequently, their liver function indexes were investigated by a microplate method and liver sections were blindly evaluated using an optical microscope by a pathologist. Subsequently, the activation state of Toll‑like receptor (TLR)3/9 signaling pathway in liver tissues was analyzed by western blotting. Additionally, the inflammatory factors produced following liver injury in peripheral blood were detected via ELISA. Following intervention with the Bushen recipe and its disassembled prescriptions, the liver function indexe alanine aminotransferase had declined, whereas cholinesterase increased. The pathological alterations of liver tissue in HBV transgenic mice were reversed by Bushen recipe and its disassembled prescriptions. In addition, the TLR3/9 signaling pathway in liver tissues of HBV transgenic mice was inhibited and inflammatory factors such as interleukin (IL)‑6, IL‑1, tumor necrosis factor‑α and interferon‑γ were reduced significantly. In conclusion, the present study demonstrated that Bushen recipe and its disassembled prescriptions repaired liver injury induced by Concanavalin A through inhibition of TLR3/9 signaling pathway.

Hepatocyte nuclear factor 1α downregulates HBV gene expression and replication by activating the NF-κB signaling pathway

The role of hepatocyte nuclear factor 1α (HNF1α) in the regulation of gene expression and replication of hepatitis B virus (HBV) is not fully understood. Previous reports have documented the induction of the expression of viral large surface protein (LHBs) by HNF1α through activating viral Sp1 promoter. Large amount of LHBs can block the secretion of hepatitis B surface antigen (HBsAg). Here we found that HNF1α overexpression inhibited HBV gene expression and replication in Huh7 cells, resulting in marked decreases in HBsAg, hepatitis B e antigen (HBeAg) and virion productions. In contrast, knockdown of endogenous HNF1α expression enhanced viral gene expression and replication. This HNF1α-mediated inhibition did not depend on LHBs. Instead, HNF1α promoted the expression of NF-κB p65 and slowed p65 protein degradation, leading to nuclear accumulation of p65 and activation of the NF-κB signaling, which in turn inhibited HBV gene expression and replication. The inhibitor of the NF-κB signaling, IκBα-SR, could abrogate this HNF1α-mediated inhibition. While the dimerization domain of HNF1α was dispensable for the induction of LHBs expression, all the domains of HNF1α was required for the inhibition of HBV gene expression. Our findings identify a novel role of HNF1α in the regulation of HBV gene expression and replication.

Targeting selenium nanoparticles combined with baicalin to treat HBV-infected liver cancer

Herein, we demonstrate baicalin-loaded selenium nanoparticles with a liver-targeting folic acid moiety to treat HBV-infected liver cancer.

The role of tumour necrosis factor in hepatitis B infection: Jekyll and Hyde

Chronic hepatitis B (CHB) is a major health problem worldwide and is associated with significant long-term morbidity and mortality. The hepatitis B virus (HBV) is a hepatotropic virus that is capable of integrating in the host nucleus permanently resulting in lifelong infection. To date, there is no definitive cure for HBV, as our current treatments cannot eradicate the viral reservoir that has integrated in the liver. Elucidating the immunopathogenesis is key to finding a therapeutic target for HBV as the virus is not in itself cytopathic but the immune response to the virus causes the majority of the cellular injury. In most cases, the virus reaches a state of equilibrium with low viral replication constrained by host immunity. Multiple cytokines have been implicated in the pathogenesis of CHB. Tumor necrosis factor (TNF) has emerged as a key player; on one hand it can facilitate immune-mediated virological control but on the other hand it can cause collateral hepatocyte damage, cirrhosis and possibly promote hepatocellular carcinoma. In this review, we discuss the current understanding of the immunopathogenesis of HBV, focusing on TNF and whether it can be harnessed in therapeutic strategies to cure HBV infection.

Association of TNF-α Gene Polymorphisms with Production of Protein and Susceptibility to Chronic Hepatitis B Infection in the South East Iranian Population

BACKGROUND

The host genetic background regulates the natural history of chronic hepatitis B virus (HBV) infection.

OBJECTIVES

The aim of this study was to investigate the association between TNF-α gene polymorphism in the promoter region and susceptibility to chronic hepatitis B virus infection.

METHODS

Four polymorphisms of TNF-α gene including -238 A/G, -308 A/G, -857 C/T, and -863 A/C were analyzed by PCR-RFLP in 100 chronic HBV infected patients (HBV group), 40 spontaneously recovered HBV subjects (SR group), and 100 healthy controls (C group). Also, serum levels of protein were monitored.

RESULTS

The study showed that the existence of -308 G, -857 C, and -863 A alleles significantly increased susceptibility to chronic HBV infection. In addition, GGCA haplotype had a higher frequency in HBV patients than C and SR groups that might be related to the natural history of the infection. Chronic HBV patients with -308 GG, -857 CC, and -863 AA genotypes had lower serum levels of TNF-α compared to those with other genotypes.

CONCLUSIONS

The results indicated that there was a positive association between susceptibility to chronic HBV infection and TNF-α polymorphism. In addition, HBV patients carrying -308 GG, -857 CC, and -863 AA genotypes with lower serum levels of TNF-α had an increased risk of infection.

Role of Some Predominant Host Immunomodulators' Single Nucleotide Polymorphisms in Severity of Hepatitis B Virus and Hepatitis C Virus Infection

Hepatitis B and C infections can be either acute or chronic. The chronic infection can culminate in liver cirrhosis and hepatocellular carcinoma. Influence of the host genetic makeup on conversion of acute to chronic infection, development of cirrhosis, and hepatocellular carcinoma is an interesting area of research. Variability in different immune system genes may account for such differences in the outcome of infection. This article discusses single nucleotide polymorphisms in different host immunomodulator genes that have been frequently reported to influence the outcome of infection and severity of disease. The genetic variability could be utilized for the prediction of disease outcome and treatment responses.

Quantitative intrahepatic HBV cccDNA correlates with histological liver inflammation in chronic hepatitis B virus infection

BACKGROUND

The aim of this study was to determine the role of baseline hepatitis B virus (HBV) forming covalently closed circular DNA (HBV cccDNA) in liver inflammation in patients infected with HBV with serum alanine aminotransferase (ALT) levels under two times the upper limit of normal (2×ULN).

METHODS

After liver biopsy and serum virological and biochemical marker screening, patients diagnosed with chronic HBV infection with serum ALT levels under 2×ULN and histological liver inflammation of less than grade G2 were prospectively recruited into this study. Recruitment took place between March 2009 and November 2010 at the Center of Infectious Disease, Sichuan University. Patient virological and biochemical markers, as well as markers of liver inflammation, were monitored.

RESULTS

A total of 102 patients were recruited and 68 met the inclusion criteria; the median follow-up was 4.1 years (range 3.9-5.2 years). During follow-up, 41 patients (60.3%) exhibited signs of inflammation. Baseline HBV cccDNA >1 copy/cell (odds ratio 9.43, p=0.049) and liver inflammation grade ≥G1 (odds ratio 5.77, p=0.046) were both independent predictors of liver inflammation.

CONCLUSIONS

A higher baseline intrahepatic HBV cccDNA level may increase the risk of liver inflammation. Further investigations will be required to validate HBV cccDNA as an intrahepatic virological marker of patients who require extended outpatient management.

Importin β Can Bind Hepatitis B Virus Core Protein and Empty Core-Like Particles and Induce Structural Changes

Hepatitis B virus (HBV) capsids are found in many forms: immature single-stranded RNA-filled cores, single-stranded DNA-filled replication intermediates, mature cores with relaxed circular double-stranded DNA, and empty capsids. A capsid, the protein shell of the core, is a complex of 240 copies of core protein. Mature cores are transported to the nucleus by a complex that includes both importin α and importin β (Impα and Impβ), which bind to the core protein's C-terminal domains (CTDs). Here we have investigated the interactions of HBV core protein with importins in vitro. Strikingly, empty capsids and free core protein can bind Impβ without Impα. Cryo-EM image reconstructions show that the CTDs, which are located inside the capsid, can extrude through the capsid to be bound by Impβ. Impβ density localized on the capsid exterior near the quasi-sixfold vertices, suggested a maximum of 30 Impβ per capsid. However, examination of complexes using single molecule charge-detection mass spectrometry indicate that some complexes include over 90 Impβ molecules. Cryo-EM of capsids incubated with excess Impβ shows a population of damaged particles and a population of "dark" particles with internal density, suggesting that Impβ is effectively swallowed by the capsids, which implies that the capsids transiently open and close and can be destabilized by Impβ. Though the in vitro complexes with great excess of Impβ are not biological, these results have implications for trafficking of empty capsids and free core protein; activities that affect the basis of chronic HBV infection.

Hepatitis B virus genome replication triggers toll-like receptor 3-dependent interferon responses in the absence of hepatitis B surface antigen

The hepatitis B virus (HBV) has been described as stealth virus subverting immune responses initially upon infection. Impaired toll-like receptor signaling by the HBV surface antigen (HBsAg) attenuates immune responses to facilitate chronic infection. This implies that HBV replication may trigger host innate immune responses in the absence of HBsAg. Here we tested this hypothesis, using highly replicative transgenic mouse models. An HBV replication-dependent expression of antiviral genes was exclusively induced in HBsAg-deficient mice. These interferon responses attributed to toll-like receptor 3 (TLR3)-activated Kupffer and liver sinusoidal endothelial cells and further controlled the HBV genome replication. However, activation of TLR3 with exogenous ligands indicated additional HBs-independent immune evasion events. Our data demonstrate that in the absence of HBsAg, hepatic HBV replication leads to Tlr3-dependent interferon responses in non-parenchymal liver cells. We hypothesize that HBsAg is a major HBV-mediated evasion mechanism controlling endogenous antiviral responses in the liver. Eradication of HBsAg as a therapeutic goal might facilitate the induction of endogenous antiviral immune responses in patients chronically infected with HBV.

Cleaved c-FLIP mediates the antiviral effect of TNF-α against hepatitis B virus by dysregulating hepatocyte nuclear factors

BACKGROUND & AIMS

Cytokines are key molecules implicated in the defense against virus infection. Tumor necrosis factor-alpha (TNF-α) is well known to block the replication of hepatitis B virus (HBV). However, the molecular mechanism and the downstream effector molecules remain largely unknown.

METHODS

In this study, we investigated the antiviral effect and mechanism of p22-FLIP (FLICE-inhibitory protein) by ectopic expression in vitro and in vivo. In addition, to provide the biological relevance of our study, we examined that the p22-FLIP is involved in TNF-α-mediated suppression of HBV in primary human hepatocytes.

RESULTS

We found that p22-FLIP, a newly discovered c-FLIP cleavage product, inhibited HBV replication at the transcriptional level in both hepatoma cells and primary human hepatocytes, and that c-FLIP conversion to p22-FLIP was stimulated by the TNF-α/NF-κB pathway. p22-FLIP inhibited HBV replication through the upregulation of HNF3β but downregulation of HNF4α, thus inhibiting both HBV enhancer elements. Finally, p22-FLIP potently inhibited HBV DNA replication in a mouse model of HBV replication.

CONCLUSIONS

Taken together, these findings suggest that the anti-apoptotic p22-FLIP serves a novel function of inhibiting HBV transcription, and mediates the antiviral effect of TNF-α against HBV replication.

Prospects and progress of DNA vaccines for treating hepatitis B

The hepatitis B virus (HBV) is a global cause of liver disease. The preventive HBV vaccine has effectively reduced the disease burden. However, an estimated 340 million chronic HBV cases are in need of treatment. Current standard therapy for chronic HBV blocks reverse transcription. As this therapy blocks viral maturation and not viral protein expression, any immune inhibition exerted by these proteins will remain throughout therapy. This may help to explain why these drugs rarely induce off-therapy responses. Albeit some restoration of immune function occurs during therapy, this is clearly insufficient to control replication. Central questions when considering therapeutic DNA vaccination as an addition to blocking virus production are as follows: what does one hope to achieve? What do we think is wrong and how can the vaccination correct this? We here discuss different scenarios with respect to the lack of success of tested DNA vaccines, and suggest strategies for improvement.

New paradigms in hepatitis B management: only diamonds are forever

INTRODUCTION

The hepatitis B virus (HBV) causes chronic hepatitis B (CHB) in ∼350 million people worldwide who have an increased risk of end-stage liver disease and/or hepatocellular carcinoma.

SOURCES OF DATA

Several peer-reviewed papers featuring new approaches to anti-HBV management. Additionally, we also reviewed recent abstract presentations at international congresses.

AREAS OF AGREEMENT

There has been great progress in CHB therapy with the development of standard and pegylated interferon (i.e. PEG-IFN) as well as nucleos/tide analogs (NAs). IFN has both antiviral and immunomodulatory effects and through immune-mediated destruction of infected hepatocytes offers the possibility of finite therapy. However, this 'killing for a cure' antiviral strategy may not be tolerated in many, especially in cirrhotic patients. NAs inhibit viral reverse transcriptase, have few side effects and prevent liver disease progression, but cannot offer a cure as they have little effect on the resilient HBV covalently closed circular DNA (cccDNA) intermediate. Moreover, NAs such as tenofovir and entecavir offer a high genetic barrier to resistance, but are expensive and not readily available in many global regions.

GROWING POINTS

Despite significant treatment advances, there is increased recognition of the need for improved anti-HBV treatments, and new virologic tests for monitoring treatment response.

AREAS OF CONTROVERSY

The role of quantitative hepatitis B surface antigen, intrahepatic cccDNA levels and viral genotype in selecting treatment candidates and refining NA stopping rules.

AREAS TIMELY FOR DEVELOPING NEW RESEARCH

Potential new therapies include viral entry inhibitors, RNA interference technologies (i.e. RNAi) and small molecules that modulate cccDNA transcription, as well as novel immunomodulatory therapies to boost HBV-specific T cell responses. The ultimate goal of new tests and anti-HBV therapies is to reduce the burden and expense of life-long CHB treatment, as 'only diamonds are forever'.

Hepatitis B: future curative strategies

PURPOSE OF REVIEW

Hepatitis B virus (HBV) causes a large proportion of chronic liver disease worldwide. The limited efficiency of current treatments based on the use of nucleotide/nucleoside analogues or interferon-alpha requires the development of new therapeutic tools for the treatment of chronic HBV. We summarize the most recent therapeutic strategies designed to directly target HBV-infected hepatocytes or to restore antiviral immunity during chronic HBV infection.

RECENT FINDINGS

Novel therapies directly target HBV-infected hepatocytes by inducing covalently closed circular DNA degradation or by inhibiting HBV entry or the expression of viral proteins. In addition, immunotherapeutic approaches may boost HBV-specific T-cell responses or stimulate the intrahepatic innate response.

SUMMARY

These new therapeutic approaches have mainly been tested in animal models. In humans, therapeutic strategies could be tailored to different chronic HBV patients in relation to their clinical and virological disease profile.

The inhibitory effect of the hepatitis B virus singly-spliced RNA-encoded p21.5 protein on HBV nucleocapsid formation

Hepatitis B virus (HBV) is the smallest DNA virus and the major cause of acute and chronic hepatitis. The 3.2 kb HBV viral genome generates four major species of unspliced viral transcript as well as several alternatively spliced RNAs. A 2.2 kb singly-spliced RNA is the most abundant spliced RNA and is widely expressed among all HBV genotypes. The expression of the singly-spliced RNA, as well as that of its encoded protein HBSP, is strongly associated with hepatopathology during HBV infection. Here, we report a novel inhibitory role of a p21.5 protein, which is encoded by a 2.2 kb singly-spliced RNA, in the modulation of HBV replication. We show that overexpression of the singly-spliced RNA is able to efficiently inhibit HBV replication. Furthermore, a mutation in the ATG start codon of the precore region completely abolishes the inhibitory effect of the singly-spliced RNA, indicating that a viral protein (p21.5) derived from the singly-spliced RNA is the mediator of the inhibition. Furthermore, p21.5 is able to form a homodimer that interacts with core dimers forming hybrid viral assembly components. Sucrose gradient fractionation revealed that co-expression of p21.5 resulted in a spread distribution pattern of core proteins ranging from low to high sucrose densities. When compared with p22, p21.5 is almost ten times more efficient at destabilizing HBV nucleocapsid assembly in Huh7 cells overexpressing either p21.5 or p22 protein. Moreover, in vivo expression of p21.5 protein by tail vein injection was found to decrease the amount of nucleocapsid in the livers of HBV-expressing BALB/c mice. In conclusion, our study reveals that the HBV 2.2 kb singly-spliced RNA encodes a 21.5 kDa viral protein that significantly interferes with the assembly of nucleocapsids during HBV nucleocapsid formation. These findings provide a possible strategy for elimination of HBV particles inside cells.

Treatment of rheumatic diseases and hepatitis B virus coinfection

We often encounter rheumatological patients coinfected with hepatitis B in daily practice. In this paper, we will discuss the basic characteristics of the virus of hepatitis B, course of infection, the safety of rituximab, tocilizumab, abatacept treatment and therapeutic recommendations in management of patients with rheumatic diseases.

Hepatitis B virus core protein sensitizes hepatocytes to tumor necrosis factor-induced apoptosis by suppression of the phosphorylation of mitogen-activated protein kinase kinase 7

Hepatitis B, which caused by hepatitis B virus (HBV) infection, remains a major health threat worldwide. Hepatic injury and regeneration from chronic inflammation are the main driving factors of liver fibrosis and cirrhosis in chronic hepatitis B. Proinflammatory tumor necrosis factor alpha (TNF-α) has been implicated as a major inducer of liver cell death during viral hepatitis. Here, we report that in hepatoma cell lines and in primary mouse and human hepatocytes, expression of hepatitis B virus core (HBc) protein made cells susceptible to TNF-α-induced apoptosis. We found by tandem affinity purification and mass spectrometry that receptor of activated protein kinase C 1 (RACK1) interacted with HBc. RACK1 was recently reported as a scaffold protein that facilitates the phosphorylation of mitogen-activated protein kinase kinase 7 (MKK7) by its upstream activators. Our study showed that HBc abrogated the interaction between MKK7 and RACK1 by competitively binding to RACK1, thereby downregulating TNF-α-induced phosphorylation of MKK7 and the activation of c-Jun N-terminal kinase (JNK). In line with this finding, specific knockdown of MKK7 increased the sensitivity of hepatocytes to TNF-α-induced apoptosis, while overexpression of RACK1 counteracted the proapoptotic activity of HBc. Capsid particle formation was not obligatory for HBc proapoptotic activity, as analyzed using an assembly-defective HBc mutant. In conclusion, the expression of HBc sensitized hepatocytes to TNF-α-induced apoptosis by disrupting the interaction between MKK7 and RACK1. Our study is thus the first indication of the pathogenic effects of HBc in liver injury during hepatitis B.

IMPORTANCE

Our study revealed a previously unappreciated role of HBc in TNF-α-mediated apoptosis. The proapoptotic activity of HBc is important for understanding hepatitis B pathogenesis. In particular, HBV variants associated with severe hepatitis may upregulate apoptosis of hepatocytes through enhanced HBc expression. Our study also found that MKK7 is centrally involved in TNF-α-induced hepatocyte apoptosis and revealed a multifaceted role for JNK signaling in this process.

Age-Dependent Immune Events during HBV Infection from Birth to Adulthood: An Alternative Interpretation

Immune responses change during the life of an individual. While this concept has been well accepted for adaptive immunity, only recently it is becoming clear that the innate immune responses also acquire distinct features in different phases of life. We believe that this concept can offer a different interpretation of the pathological manifestations that can be observed in HBV-infected subjects during the patient’s life. Here, we will review the age-related immunopathological features of HBV infection and discuss how the different virological and clinical manifestations might be linked to the developmental pathway of the immune system from newborns to adults. We will discuss how the age of patients can affect the degree of inflammatory responses, but not the levels of antiviral specific immunity. We then propose that the different clinical manifestations occurring during the natural history of HBV infection are related to the host ability to trigger an inflammatory immune response.

The immune tolerant phase of chronic HBV infection: new perspectives on an old concept

Chronic hepatitis B virus (HBV) infection progresses through distinct disease phases that are strongly associated with patient age. The so-called immune tolerant (IT) phase represents the classical early phase of infection; it is associated with high levels of HBV replication and lack of clinical signs of liver Inflammation. Whether this phase of HBV infection is also associated with immunological features of "tolerance' has recently been challenged. Here, we review the data that dispute this concept of immune tolerance and then propose an alternative interpretation of the immunopathological events that take place during this early phase of CHB infection.

Functions of invariant NK T cells are modulated by TLR ligands and IFN-α

Invariant NK T (iNKT) cells perform numerous immunoregulatory functions. In mice, they express a unique and invariant Vα14-Jα18 rearrangement of α chain in their TCR recognizing glycolipid Ags presented by CD1d. This recognition results in the rapid release of both Th1- and Th2-type cytokines, making them early mediators of the immune response. Owing to their rapid activation and genetic rigidity of their TCR, iNKT cells share characteristics with innate lymphocytes. Therefore, we investigated whether iNKT cells could be induced to express TLRs, a class of pathogen recognition receptor. Mouse iNKT cells were stimulated with anti-CD3 monoclonal Ab and IFN-α, resulting in an increase in the transcription of TLRs 3, 5, 7 and 9, and increased surface expression of TLR3. These cells were subsequently stimulated with TLR ligands, resulting in an increase in the production of IFN-γ, IL-4 and TNF-α. Supernatants from these cells also increased macrophage production of IL-6 and prostaglandin E2, and increased their phagocytic activity and CD80 expression. These supernatants also reduced vesicular stomatitis virus-GFP replication in fibroblasts. This study demonstrates the role of IFN-α in iNKT cell activation, as well as the direct modulatory effects of TLR ligands on iNKT cell function, including antiviral activity.

Adenoviral delivery of recombinant hepatitis B virus expressing foreign antigenic epitopes for immunotherapy of persistent viral infection

We previously reported a proof-of-concept study for curing chronic hepatitis B virus (HBV) infection using a foreign-antigen recombinant HBV (rHBV) as a gene therapy vector. Targeted elimination of wild-type HBV (wtHBV)-infected cells could be achieved by functionally activating an in situ T-cell response against the foreign antigen. However, as chronic HBV infection spreads to all hepatocytes, specific targeting of virus-infected cells is thought to be less critical. It is also feared that rHBV may not induce active immunization in a setting resembling natural infection. For this immunotherapeutic approach to be practically viable, in the present study, we used a recombinant adenovirus (rAd) vector for rHBV delivery. The rAd vector allowed efficient transduction of wtHBV-producing HepG2 cells, with transferred rHBV undergoing dominant viral replication. Progeny rHBV virions proved to be infectious, as demonstrated in primary tupaia hepatocytes. These results greatly expanded the antiviral capacity of the replication-defective rAd/rHBV in wtHBV-infected liver tissue. With prior priming in the periphery, transduction with rAd/rHBV attracted a substantial influx of the foreign-antigen-specific T-effector cells into the liver. Despite the fully activated T-cell response, active expression of rHBV was observed for a prolonged time, which is essential for rHBV to achieve sustained expansion. In a mouse model of HBV persistence established by infection with a recombinant adeno-associated virus carrying the wtHBV genome, rAd/rHBV-based immunotherapy elicited a foreign-antigen-specific T-cell response that triggered effective viral clearance and subsequent seroconversion to HBV. It therefore represents an efficient strategy to overcome immune tolerance, thereby eliminating chronic HBV infection.

IMPORTANCE

Adenovirus-delivered rHBV activated a foreign-antigen-specific T-cell response that abrogated HBV persistence in a mouse model. Our study provides further evidence of the potential of foreign-antigen-based immunotherapy for the treatment of chronic HBV infection.

Circulating cytokines and histological liver damage in chronic hepatitis B infection

Each phase of hepatitis B infection stimulates distinct viral kinetics and host immune responses resulting in liver damage and hepatic fibrosis. Our objective has been to correlate host inflammatory immune response including circulating Th1 and Th2 cytokines in patients with chronic hepatitis B infection with liver histopathology. Sixty-four patients with chronic hepatitis B without previous treatment were recruited. The liver histology and histological activity index were assessed for various degrees of necroinflammation and hepatic fibrosis. We determined circulating levels of the Th1 and Th2 cytokines. Forty-six males and 18 females at a median age of 34.5 years were studied. HBeAg was present in 28/64 (43.75%) of the patients. In patients negative for HBeAg, IL-10 and IFN-gamma were significantly correlated with degrees of necroinflammation (r = 0.34, r = 0.38, resp.; P < 0.05). Moreover, TNF-alpha was significantly correlated with degrees of fibrosis (r = 0.35; P < 0.05), and IL-10 and TNF-alpha were significantly correlated with significant fibrosis (r = 0.39, r = 0.35, resp.; P < 0.05). These correlations were found in the HBeAg negative group as opposed to the HBeAg positive group. In HBeAg negative patients, circulating cytokines IL-10 and IFN-gamma were correlated with degrees of necroinflammation, whereas IL-10 and TNF-alpha were correlated with significant fibrosis.

Inhibition of hepatitis B virus replication by the host zinc finger antiviral protein

The zinc finger antiviral protein (ZAP) is a mammalian host restriction factor that inhibits the replication of a variety of RNA viruses, including retroviruses, alphaviruses and filoviruses, through interaction with the ZAP-responsive elements (ZRE) in viral RNA, and recruiting the exosome to degrade RNA substrate. Hepatitis B virus (HBV) is a pararetrovirus that replicates its genomic DNA via reverse transcription of a viral pregenomic (pg) RNA precursor. Here, we demonstrate that the two isoforms of human ZAP (hZAP-L and -S) inhibit HBV replication in human hepatocyte-derived cells through posttranscriptional down-regulation of viral pgRNA. Mechanistically, the zinc finger motif-containing N-terminus of hZAP is responsible for the reduction of HBV RNA, and the integrity of the four zinc finger motifs is essential for ZAP to bind to HBV RNA and fulfill its antiviral function. The ZRE sequences conferring the susceptibility of viral RNA to ZAP-mediated RNA decay were mapped to the terminal redundant region (nt 1820–1918) of HBV pgRNA. In agreement with its role as a host restriction factor and as an innate immune mediator for HBV infection, ZAP was upregulated in cultured primary human hepatocytes and hepatocyte-derived cells upon IFN-α treatment or IPS-1 activation, and in the livers of hepatitis B patients during immune active phase. Knock down of ZAP expression increased the level of HBV RNA and partially attenuated the antiviral effect elicited by IPS-1 in cell cultures. In summary, we demonstrated that ZAP is an intrinsic host antiviral factor with activity against HBV through down-regulation of viral RNA, and that ZAP plays a role in the innate control of HBV replication. Our findings thus shed light on virus-host interaction, viral pathogenesis, and antiviral approaches.

The dynamics of virus and host interaction greatly influence viral pathogenesis, and host cells have evolved multiple mechanisms to inhibit viral replication. Since it was first discovered as a cellular restriction factor for retroviruses, the host-encoded zinc finger antiviral protein (ZAP) has been shown to antagonize a variety of viral species, possibly through a common mechanism by which ZAP targets viral RNA for degradation. Here we report that hepatitis B virus (HBV) is also vulnerable to ZAP-mediated viral RNA reduction. ZAP is able to interact with HBV RNA through its zinc finger motifs, and the ZAP-responsive element which determines ZAP's antiviral specificity and activity is located within the 100-nucleotide-long terminal redundant region in the viral RNA genome. While the replication of HBV is constitutively restricted under the basal expression of intrahepatic ZAP, activation of host innate defenses, and potentially the acquired immune responses as well, could further elevate ZAP expression to suppress HBV replication. Therefore, our study not only expands the antiviral spectrum of ZAP, but also provides cumulative and novel information for a better understanding of ZAP biology and antiviral mechanisms. We also envision that the endogenous or engineered ZAP could be utilized in the future for development of therapeutic means to treat chronic hepatitis B, which currently affects more than 5% of the world's population.

Accumulation of the mutations in basal core promoter of hepatitis B virus subgenotype C1 increase the risk of hepatocellular carcinoma in Southern China

Hepatitis B virus (HBV) genotype C is associated with the development of hepatocellular carcinoma (HCC). In addition, HBV subgenotype C1 is the major subgenotype in Southern China. The aim of this study was to investigate whether there was the specific mutation patterns in HBV/C1 associated with Southern Chinese patients with HCC.

METHODS

Mutations in HBV basal core promoter (BCP) and their association with HCC were assessed in a matched cross-sectional control study of 102 HCC and 105 chronic hepatitis (CH) patients (from Guangdong, China) infected with HBV/C1. Functional analysis of HBx mutants was performed by the colony formation assay and the luciferase assays.

RESULTS

T1762/A1764 double mutations was frequently found in patients infected with HBV/C1, regardless of clinical status (64.7% in HCC and 51.4% in CH, P>0.05). Unexpectedly, the adjacent V1753 or A1768 mutation significantly increased the risk of HCC (P<0.05). Moreover, the prevalence of triple or quadruple mutations in BCP was significantly higher in patients with HCC than those with CH, particularly for HBeAg-positive-carriers (P<0.05). Functional analysis revealed that T1762/A1764 mutation alone did not alter the transcriptional activity and the inhibitory effects on cell proliferation of HBx, but triple or quadruple mutations largely abrogated this effect.

CONCLUSIONS

Accumulation of mutations involving V1753 or/and A1768 in addition to T1762/A1764 in BCP region were closely related to HCC among the patients infected with HBV/C1, particularly for HBeAg-positive-carriers. The increased risk of HCC caused by BCP variants may be attributable partially to modifying the biological functions of HBx.

The TNF-α -308 Promoter Gene Polymorphism and Chronic HBV Infection

Background and Aims. TNF-α -308 allele promoter polymorphism has been known to be a potential prognostic factor in patients with chronic HBV infection. We tried to determine how TNF-α -308 allele promoter polymorphism would affect the prognosis in patients with chronic HBV infection. Methods. We searched MEDLINE, EMBASE, and reference lists of relevant review articles related to the association between “TNF-α G-308A promoter polymorphism” with “chronic HBV infection”. We only focused on searching -308 locus in published studies. We reviewed 21 original articles about TNF-α -308 allele polymorphism and its effect on prognosis in patients with chronic HBV infection and discussed the results. Results. conflicting results were observed. The results were divided into 3 groups including neutral, negative, and positive associations between TNF-α -308 allele polymorphism and prognosis in patients with chronic HBV infection. We summarized the primary data as a table. Conclusions. Authors concluded that although there is an upward trend in evidence to claim that there is a positive relation between TNF-α G-308A promoter polymorphisms and resolution of chronic HBV infection, due to many biases and limitations observed in reviewed studies, an organized well-designed study is needed for clarifying the real association.

Effect of interferon-γ and tumor necrosis factor-α on hepatitis B virus following lamivudine treatment

AIM

To evaluate anti-hepatitis B virus (HBV) activity and cytotoxicity of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) following lamivudine treatment of HepG2.2.15 cells.

METHODS

HepG2.2.15 cells were treated with 2 μmol/L lamivudine for 16 d (lamivudine group), cultured for 10 d, followed by 5 ng/mL TNF-α and 1000 U/mL IFN-γ for 6 d (cytokine group), or treated with 2 μmol/L lamivudine for 10 d followed by 5 ng/mL TNF-α and 1000 U/mL IFN-γ for 6 d (sequential group), or cultured without additions for 16 d (control group). Intracellular DNA was extracted from 3 × 10(5) HepG2.2.15 cells from each group. The extracted DNA was further purified with mung bean nuclease to remove HBV relaxed circular DNA that may have remained. Both HBV covalently closed circular DNA (cccDNA) and HBV DNA were examined with real-time polymerase chain reaction. The titers of hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) were quantified with enzyme-linked immunosorbent assay. Cell viability was measured with the cell counting kit-8 assay.

RESULTS

Compared to lamivudine alone (22.63% ± 0.12%), both sequential (51.50% ± 0.17%, P = 0.034) and cytokine treatment (49.66% ± 0.06%, P = 0.041) showed a stronger inhibition of HBV cccDNA; the difference between the sequential and cytokine groups was not statistically significant (51.50% ± 0.17% vs 49.66% ± 0.06%, P = 0.88). The sequential group showed less inhibition of HBV DNA replication than the lamivudine group (67.47% ± 0.02% vs 82.48% ± 0.05%, P = 0.014); the difference between the sequential and cytokine groups was not statistically significant (67.47% ± 0.02% vs 57.45% ± 0.07%, P = 0.071). The levels of HBsAg and HBeAg were significantly decreased in the sequential treatment group compared to the other groups [HBsAg: 3.48 ± 0.04 (control), 3.09 ± 0.08 (lamivudine), 2.55 ± 0.13 (cytokine), 2.32 ± 0.08 (sequential), P = 0.042 for each between-group comparison; HBeAg: 3.48 ± 0.01 (control), 3.08 ± 0.08 (lamivudine), 2.57 ± 0.15 (cytokine), 2.34 ± 0.12 (sequential), P = 0.048 for each between-group comparison]. Cell viability in the cytokine group was reduced to 58.03% ± 8.03% compared with control cells (58.03% ± 8.03% vs 100%, P = 0.000). Lamivudine pretreatment significantly reduced IFN-γ + TNF-α-mediated toxicity of HepG2.2.15 cells [85.82% ± 5.43% (sequential) vs 58.03% ± 8.03% (cytokine), P = 0.002].

CONCLUSION

Sequential treatment overcame the lower ability of lamivudine alone to inhibit cccDNA and precluded the aggressive cytotoxicity involving IFN-γ and TNF-α by decreasing the viral load.

Inhibition of hepatitis B virus replication by cIAP2 involves accelerating the ubiquitin-proteasome-mediated destruction of polymerase

Cellular inhibitor of apoptosis protein 2 (cIAP2) is a potent suppressor of apoptotic cell death. We have shown previously that cIAP2 is involved in the tumor necrosis factor alpha (TNF-α)-induced anti-hepatitis B virus (HBV) response; however, the mechanism for this antiviral effect remains unclear. In the present study, we demonstrate that cIAP2 can significantly reduce the levels of HBV DNA replication intermediates but not the total viral RNA or core protein levels. Domain-mapping analysis revealed that the carboxy-terminal domains of cIAP2 were indispensable for this anti-HBV ability and that an E3 ligase-deficient mutant of cIAP2 (termed cIAP2*) completely lost its antiviral activity. We further identified HBV polymerase as the target of cIAP2. Overexpression of cIAP2 but not cIAP2* reduced polymerase protein levels, while cIAP2 knockdown increased polymerase expression. In addition, we observed that cIAP2 promoted the degradation of the viral polymerase through a proteasome-dependent pathway. Further experiments demonstrated that cIAP2 can bind to polymerase and promote its polyubiquitylation. Finally, we found that cIAP2 downregulated the encapsidation of HBV pregenomic RNA. Taken together, these data reveal a novel mechanism for the inhibition of HBV replication by cIAP2 via acceleration of the ubiquitin-proteasome-mediated decay of polymerase and reduction of the encapsidation of HBV pregenomic RNA, making this mechanism a novel strategy for HBV therapy.

Relationship between TNF-<alpha> gene promoter polymorphisms and outcomes of hepatitis B virus infections: a meta-analysis

Background

The clearance of hepatitis B virus (HBV) is a complex process which may be influenced by many factors including polymorphisms in the tumor necrosis factor <alpha> (TNF-<alpha>) gene promoter. However, previous reports regarding the relationship between polymorphisms in the TNF-<alpha> promoter and HBV clearance have been inconsistent. Therefore, we performed a meta-analysis on a large population to address this inconsistency.

Methods

A meta-analysis was performed to examine the association between TNF-<alpha> promoter polymorphisms (-1031T/C, -863C/A, -857C/T, -308G/A and-238G/A) and chronic hepatitis B infection. Odds ratio (OR) and its 95 % confidence interval (CI) were used.

Results

Twelve studies were chosen in our meta-analysis, involving 2,754 chronic HBV infection cases and 1,630 HBV clearance cases. The data showed that TNF-<alpha>-863 CC genotype was significantly associated with HBV clearance (-863 CC vs. AA: OR, 0.64; 95% CI, [0.42, 0.97]; p = 0.04) while patients carrying -308 GG genotype had a significantly increased risk of HBV persistence compared with those with GA or AA genotype (GG vs. GA+AA: OR, 1.35; 95% CI, [1.08, 1.70]; p = 0.01). For the other polymorphisms, no association with HBV infection outcome was found.

Conclusions

The data showed that polymorphisms -863 A and -308 G in the TNF-<alpha> gene promoter region might be risk factors for HBV persistence. Furthermore, ethnicity might play an important role in HBV infection outcome, leading to conflicting results. More studies on individuals from various ethnic groups will be necessary to determine the role of TNF-<alpha> promoter polymorphisms in the outcome of HBV infection.

The C-terminal region of the hepatitis B virus X protein is essential for its stability and function

More than 350 million people worldwide are chronically infected with the human hepatitis B virus (HBV). Chronic HBV infections are associated with the development of hepatocellular carcinoma. While the mechanism of HBV-associated carcinoma remains undefined, it is thought to involve a combination of a continuous inflammatory response to HBV-infected hepatocytes and activities of HBV proteins such as the HBV X protein (HBx). HBx stimulates HBV replication; however, the mechanism by which HBx stimulates HBV replication remains incompletely understood. Studies performed with the woodchuck hepatitis virus (WHV) in woodchucks demonstrated that a C-terminally truncated mutant of the WHV X protein could not stimulate WHV replication. However, whether the C-terminus of HBx is important for HBx-stimulation of HBV replication is unclear. We have constructed C-terminal truncation mutants of HBx and have demonstrated that the C-terminus of HBx impacts HBx stability, HBx activation of transcription, and HBx stimulation of HBV replication. These observations highlight the impact of the HBx C-terminus on HBx activities and the importance of directly analyzing HBx expression and functions in HBV-associated tumors that contain chromosomal integrants of HBV with truncations of the HBx gene.

Enhancing the antihepatitis B virus immune response by adefovir dipivoxil and entecavir therapies

Chronicity of hepatitis B (CHB) infection is characterized by a weak immune response to the virus. Entecavir (ETV) and adefovir dipivoxil (ADV) are effective in suppressing hepatitis B virus (HBV) replication. However, the underlying immune mechanism in the antiviral response of patients treated with nucleoside or nucleotide analogs is not clearly understood. In this study, regulatory T cells (Tregs) and intracellular cytokines, including IL-2, interferon (IFN)-γ, tumor-necrosis factor (TNF)-α and IL-4, were measured prior to and at 12, 24, 36 and 48 weeks after treatment with ETV or ADV. The cytokines were increased from 24 to 48 weeks after treatment. Higher levels of Th1 cytokines were observed with ETV (n=29) versus ADV (n=28) treatment. By contrast, the numbers of Tregs in both groups were decreased. The altered cytokine profile and cellular component was accompanied by a decrease in HBV DNA levels in both groups, which may contribute to their therapeutic effect in CHB infection. Our findings suggest that the antiviral effect of the drugs may be attributed not only to their direct effect on virus suppression but also to their immunoregulatory capabilities.

Can engineered "designer" T cells outsmart chronic hepatitis B?

More than 350 million people worldwide are persistently infected with human heptatitis B virus (HBV) and at risk to develop liver cirrhosis and hepatocellular carcinoma making long-term treatment necessary. While a vaccine is available and new antiviral drugs are being developed, elimination of persistently infected cells is still a major issue. Recent efforts in adoptive cell therapy are experimentally exploring immunotherapeutic elimination of HBV-infected cells by means of a biological attack with genetically engineered "designer" T cells.