Hepatitis B virus infection and the immune response: The big questions

New window into hepatitis B in Africa: Liver sampling combined with single cell omics enables deep and longitudinal assessment of intrahepatic immunity in Zambia

In Lusaka, Zambia, we introduced liver fine needle aspiration (FNA) into a research cohort of adults with treatment-naïve chronic hepatitis B virus (HBV) infection, with and without HIV coinfection, as well as with acute HBV infection. Over 117 enrollment and 47 longitudinal FNAs (at 1 year follow-up), we established participant acceptability and safety. We also demonstrated the quality of the material through single cell RNA sequencing of selected enrollment FNAs, which revealed a range of immune cells. This approach can drive new insights into HBV immunology, informing cure strategies, and can improve our understanding of HBV natural history in Africa.

Chronic Hepatitis B Infection: New Approaches towards Cure

Chronic hepatitis B virus (HBV) infection leads to the development of cirrhosis and hepatocellular carcinoma. Lifelong treatment with nucleotides/nucleoside antiviral agents is effective at suppressing HBV replication, however, adherence to daily therapy can be challenging. This review discusses recent advances in the development of long-acting formulations for HBV treatment and prevention, which could potentially improve adherence. Promising new compounds that target distinct steps of the virus life cycle are summarized. In addition to treatments that suppress viral replication, curative strategies are focused on the elimination of covalently closed circular DNA and the inactivation of the integrated viral DNA from infected hepatocytes. We highlight promising long-acting antivirals and genome editing strategies for the elimination or deactivation of persistent viral DNA products in development.

Recent Insights into the Role of B Cells in Chronic Hepatitis B and C Infections

Chronic viral hepatitis infections, caused by the hepatitis B or C virus, are a major global health problem causing an estimated one million deaths each year. Immunological studies have classically focused on T cells, while B cells have largely been neglected. Emerging evidence, however, highlights a role for B cells in the immunopathogenesis of chronic hepatitis B and C infections. B cell responses appear to be altered across different clinical phases of chronic HBV infection and across stages of disease in chronic HCV infection. These B cell responses show signs of a more activated state with a simultaneous enrichment of phenotypically exhausted atypical memory B cells. Despite the fact that studies show an activating B cell signature in chronic viral hepatitis infection, antibody responses to HBsAg remain impaired in chronic HBV infection, and glycoprotein E2-specific neutralizing antibody responses remain delayed in the acute phase of HCV infection. At the same time, studies have reported that a subset of HBV- and HCV-specific B cells exhibit an exhausted phenotype. This may, at least in part, explain why antibody responses in chronic HBV and HCV patients are suboptimal. Here, we summarize recent findings and discuss upcoming research questions while looking forward to how new single-cell technologies could provide novel insights into the role of B cells in chronic viral hepatitis infections.

Clinical Utility of Quantitative HBV Core Antibodies for Solving Diagnostic Dilemmas

The present-day management of hepatitis B virus (HBV) infection relies on constant and appropriate monitoring of viral activity, disease progression and treatment response. Traditional HBV infection biomarkers have many limitations in predicting clinical outcomes or therapy success. Quantitation of HBV core antibodies (qAnti-HBc) is a new non-invasive biomarker that can be used in solving multiple diagnostic problems. It was shown to correlate well with infection phases, level of hepatic inflammation and fibrosis, exacerbations during chronic infection and presence of occult infection. Further, the level of qAnti-HBc was recognised as predictive of spontaneous or therapy-induced HBeAg and HBsAg seroclearance, relapse after therapy discontinuation, re-infection after liver transplantation and viral reactivation upon immunosuppression. However, qAnti-HBc cannot be relied upon as a single diagnostic test to solve all dilemmas, and its diagnostic and prognostic power can be much improved when combined with other diagnostic biomarkers (HBV DNA, HBeAg, qHBsAg and anti-HBs antibodies). The availability of commercial qAnti-HBc diagnostic kits still needs to be improved. The comparison of results from different studies and definitions of universal cut-off values continue to be hindered because many methods are only semi-quantitative. The clinical utility of qAnti-HBc and the methods used for its measurement are the focus of this review.

A systemic review of T-cell epitopes defined from the proteome of SARS-CoV-2

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection remains in a global pandemic, and no eradicative therapy is currently available. Host T cells have been shown to play a crucial role in the antiviral immune protection and pathology in Coronavirus disease 2019 (COVID-19) patients; thus, identifying sufficient T-cell epitopes from the SARS-CoV-2 proteome can contribute greatly to the development of T-cell epitope vaccines and the precise evaluation of host SARS-CoV-2-specific cellular immunity. This review presents a comprehensive map of T-cell epitopes functionally validated from SARS-CoV-2 antigens, the human leukocyte antigen (HLA) supertypes to present these epitopes, and the strategies to screen and identify T-cell epitopes. To the best of our knowledge, a total of 1349 CD8+ T-cell epitopes and 790 CD4+ T-cell epitopes have been defined by functional experiments thus far, but most are presented by approximately twenty common HLA supertypes, such as HLA-A0201, A2402, B0702, DR15, DR7 and DR11 molecules, and 74-80% of the T-cell epitopes are derived from S protein and nonstructural protein. These data provide useful insight into the development of vaccines and specific T-cell detection systems. However, the currently defined T-cell epitope repertoire cannot cover the HLA polymorphism of major populations in an indicated geographic region. More research is needed to depict an overall landscape of T-cell epitopes, which covers the overall SARS-CoV-2 proteome and global patients.

The scientific basis of combination therapy for chronic hepatitis B functional cure

Functional cure of chronic hepatitis B (CHB) - or hepatitis B surface antigen (HBsAg) loss after 24 weeks off therapy - is now the goal of treatment, but is rarely achieved with current therapy. Understanding the hepatitis B virus (HBV) life cycle and immunological defects that lead to persistence can identify targets for novel therapy. Broadly, treatments fall into three categories: those that reduce viral replication, those that reduce antigen load and immunotherapies. Profound viral suppression alone does not achieve quantitative (q)HBsAg reduction or HBsAg loss. Combining nucleos(t)ide analogues and immunotherapy reduces qHBsAg levels and induces HBsAg loss in some patients, particularly those with low baseline qHBsAg levels. Even agents that are specifically designed to reduce viral antigen load might not be able to achieve sustained HBsAg loss when used alone. Thus, rationale exists for the use of combinations of all three therapy types. Monitoring during therapy is important not just to predict HBsAg loss but also to understand mechanisms of HBsAg loss using viral and immunological biomarkers, and in selected cases intrahepatic sampling. We consider various paths to functional cure of CHB and the need to individualize treatment of this heterogeneous infection until a therapeutic avenue for all patients with CHB is available.

Multi-parametric analysis of human livers reveals variation in intrahepatic inflammation across phases of chronic hepatitis B infection

BACKGROUND & AIMS

Chronic HBV is clinically categorized into 4 phases by a combination of serum HBV DNA levels, HBeAg status and alanine aminotransferase (ALT): immunotolerant (IT), immune-active (IA), inactive carrier (IC) and HBeAg-negative hepatitis (ENEG). Immune and virological measurements in the blood have proven useful but are insufficient to explain the interrelation between the immune system and the virus since immune dynamics differ in the blood and liver. Furthermore, the inflammatory response in the liver and parenchymal cells cannot be fully captured in blood.

METHODS

Immunological composition and transcriptional profiles of core needle liver-biopsies in chronic HBV phases were compared to those of healthy controls by multiplex immunofluorescence and RNA-sequencing (n = 37 and 78, respectively) analyses.

RESULTS

Irrespective of the phase-specific serological profiles, increased immune-gene expression and frequency was observed in chronic HBV compared to healthy livers. Greater transcriptomic deregulation was seen in IA and ENEG (172 vs. 243 DEGs) than in IT and IC (13 vs. 35 DEGs) livers. Interferon-stimulated genes, immune-activation and exhaustion genes (ICOS, CTLA4, PDCD1) together with chemokine genes (CXCL10, CXCL9) were significantly induced in IA and ENEG livers. Moreover, distinct immune profiles associated with ALT elevation and a more accentuated immune-exhaustion profile (CTLA4, TOX, SLAMF6, FOXP3) were observed in ENEG, which set it apart from the IA phase (LGALS9, PDCD1). Interestingly, all HBV phases showed downregulation of metabolic pathways vs. healthy livers (fatty and bile acid metabolism). Finally, increased leukocyte infiltrate correlated with serum ALT, but not with HBV DNA or viral proteins.

CONCLUSION

Our comprehensive multi-parametric analysis of human livers revealed distinct inflammatory profiles and pronounced differences in intrahepatic gene profiles across all chronic HBV phases in comparison to healthy liver.

LAY SUMMARY

Immunological studies on chronic HBV remain largely restricted to assessment of peripheral responses due to the limited access to the site of infection, the liver. In this study, we comprehensively analyzed livers from a well-defined cohort of patients with chronic HBV and uninfected controls with state-of-the-art techniques, and evaluated the differences in gene expression profiles and inflammation characteristics across distinct disease phases in patients with chronic HBV.

Viral hepatitis: A narrative review of hepatitis A–E

Viral hepatitis continues to be a major health concern leading to hepatic decompensation ranging from acute hepatitis to cirrhosis and hepatocellular carcinoma. The hepatic and extrahepatic manifestations are not only debilitating but also associated with a significant economic burden. Over the last two decades, the field of virology has made significant breakthroughs leading to a better understanding of the pathophysiology of viral hepatitis, which in turn has led to new therapeutic options. The advent of direct-acting antiviral agents changed the landscape of hepatitis C virus (HCV) therapy, and new drugs are in the pipeline for chronic hepatitis B virus (HBV) treatment. There has also been a significant emphasis on screening and surveillance programs, widespread availability of vaccines, and linkage of care. Despite these efforts, significant gaps persist in care, and there is a pressing need for increased collaboration and teamwork across the globe to achieve a reduction of disease burden and elimination of HBV and HCV.

Early Treatment Consideration in Patients with Hepatitis B 'e' Antigen-Positive Chronic Infection: Is It Time for a Paradigm Shift?

Chronic hepatitis B (CHB) is associated with significant morbidity and mortality, due to the adverse sequelae of cirrhosis and hepatocellular carcinoma (HCC). To date, antiviral therapy has been reserved for patients with ostensibly active liver disease, fibrosis or cirrhosis, and/or increased risk of HCC. Historically, patients with hepatitis B 'e' antigen (HBeAg)-positive chronic infection, were not offered antiviral therapy. Nevertheless, there has been compelling evidence emerging in recent years, demonstrating that this disease phase is in fact not characterized by immunological tolerance. HBV integration into the human genome is a frequent event found in these patients. Additionally, it may well be associated with active inflammation and fibrosis, even in the presence of persistently normal liver enzymes. Likewise, it appears that the mechanisms of hepatocarcinogenesis are already present during this early stage of the disease. This was reflected in the European Association for the Study of the Liver (EASL) guidelines, where treating patients above the age of 30 years with HBeAg-positive chronic infection was proposed. Lowering the treatment threshold to broaden treatment eligibility is likely to slow disease progression and reduce the risk of developing HCC. The current review discusses the reasons to consider early antiviral therapy in HBeAg-positive chronic infection.

[Mitochondrial dysfunction as a new therapeutic target to restore exhausted immune responses against HBV]

Dans le cadre d’un partenariat avec médecine/sciences, et pour la quatrième année consécutive, des étudiants du module d’enseignement « d’immunologie virologie et cancer » du Master de cancérologie de Lyon présentent une analyse d’articles scientifiques récents faisant état d’observations innovantes et importantes. Ce travail a été encadré par des chercheurs confirmés du Centre de Recherche en Cancérologie de Lyon (CRCL). Le Master de cancérologie (université Claude Bernard Lyon1 - VetAgroSup) accueille chaque année 40 étudiants en M1 et environ 80 en M2. Ce master dit « d’excellence » (master international labellisé Université de Lyon) assure aux étudiants de M1 une formation à la cancérologie reposant sur un socle de base commun (biologie cellulaire, moléculaire, immunologie, bio-statistique, épidémiologie, recherche translationnelle, etc.). Les étudiants de M2 peuvent choisir l’un des parcours suivants : 1) Biologie du Cancer ; 2) Innovations thérapeutiques en Cancérologie ; 3) Médecine de précision en Cancérologie ; 4) Cancer Bio-engineering.

Le Master de cancérologie de Lyon repose sur une forte implication des chercheurs et enseignants-chercheurs du laboratoire d'excellence en développement et cancérologie (LabEx DEVweCAN), ainsi que sur un partenariat solide avec plusieurs instituts à travers le monde dont le MIT (Massachusetts Institute of Technology, Cambridge, États-Unis), l'université d'Harvard (Boston, États-Unis), l'université de San Diego (États-Unis), University of City of London (UCL), le Beatson Institute de Glasgow (Royaume-Uni), les universités de Shanghai Jiao Tong (République populaire de Chine, RPC), de Tokyo et de Tohoku (Japon), de Melbourne (Australie) et d'Auckland (Nouvelle-Zélande).

A Systematic Review of T Cell Epitopes Defined from the Proteome of Hepatitis B Virus

Hepatitis B virus (HBV) infection remains a worldwide health problem and no eradicative therapy is currently available. Host T cell immune responses have crucial influences on the outcome of HBV infection, however the development of therapeutic vaccines, T cell therapies and the clinical evaluation of HBV-specific T cell responses are hampered markedly by the lack of validated T cell epitopes. This review presented a map of T cell epitopes functionally validated from HBV antigens during the past 33 years; the human leukocyte antigen (HLA) supertypes to present these epitopes, and the methods to screen and identify T cell epitopes. To the best of our knowledge, a total of 205 CD8⁺ T cell epitopes and 79 CD4⁺ T cell epitopes have been defined from HBV antigens by cellular functional experiments thus far, but most are restricted to several common HLA supertypes, such as HLA-A0201, A2402, B0702, DR04, and DR12 molecules. Therefore, the currently defined T cell epitope repertoire cannot cover the major populations with HLA diversity in an indicated geographic region. More researches are needed to dissect a more comprehensive map of T cell epitopes, which covers overall HBV proteome and global patients.

T follicular helper cells improve the response of patients with chronic hepatitis B to interferon by promoting HBsAb production

BACKGROUND AND AIMS

Hepatitis B surface antigen (HBsAg) seroconversion is considered the optimal outcome of the treatment of chronic hepatitis B virus (HBV) infection. In this study, we aimed to determine the cellular and molecular mechanisms by which pegylated interferon alpha (PEG-IFN-α) improves the seroconversion rate in patients with chronic hepatitis B (CHB).

METHODS

Flow cytometry was performed using circulating T follicular helper (TFH) cells from 15 healthy individuals and 45 patients with CHB presenting different treatment responses [complete response group (CRG), incomplete response group (ICRG), and nonresponse group (NRG)] to the standard 48-week regimen of PEG-IFN-α monotherapy to examine the significance of circulating TFH cells in the therapeutic response of patients with CHB to PEG-IFN-α. In addition, the capacities of different TFH subsets to activate B cells and stimulate IgG production were assessed by performing coculture experiments.

RESULTS

Longitudinal analysis revealed specific and significant increases in the numbers of CD40L⁺CD4⁺CXCR5⁺ TFH cells in the CRG compared with the NRG and ICRG. According to the results of in vitro coculture experiments, blocking CD40-CD40L signaling, but not ICOS-ICOSL signaling, specifically inhibits B-cell activation and IgG production. HBV may impair TFH cell function by enhancing inhibitory regulatory T-cell activity. Transcriptome analysis further revealed the upregulation of CD40L, but not of ICOS, in TFH cells isolated from the CRG.

CONCLUSIONS

TFH cells, particularly those with CD40L expression, stimulate B-cell differentiation and improve the HBsAg seroconversion rate in patients with CHB treated with PEG-IFN-α monotherapy.

A quantitative systems pharmacology model for acute viral hepatitis B

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Mechanistic model characterizing acute immune response and HBV system interactions.

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Key role of the cellular and regulatory response triggering hepatitis B chronicity.

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Modelling framework to easily incorporate and explore additional biological mechanisms.

Hepatitis B liver infection is caused by hepatitis B virus (HBV) and represents a major global disease problem when it becomes chronic, as is the case for 80–90% of vertical or early life infections. However, in the vast majority (>95%) of adult exposures, the infected individuals are capable of mounting an effective immune response leading to infection resolution. A good understanding of HBV dynamics and the interaction between the virus and immune system during acute infection represents an essential step to characterize and understand the key biological processes involved in disease resolution, which may help to identify potential interventions to prevent chronic hepatitis B.

In this work, a quantitative systems pharmacology model for acute hepatitis B characterizing viral dynamics and the main components of the innate, adaptive, and tolerant immune response has been successfully developed. To do so, information from multiple sources and across different organization levels has been integrated in a common mechanistic framework. The final model adequately describes the chronology and plausibility of an HBV-triggered immune response, as well as clinical data from acute patients reported in the literature. Given the holistic nature of the framework, the model can be used to illustrate the relevance of the different immune pathways and biological processes to ultimate response, observing the negligible contribution of the innate response and the key contribution of the cellular response on viral clearance. More specifically, moderate reductions of the proliferation of activated cytotoxic CD8+ lymphocytes or increased immunoregulatory effects can drive the system towards chronicity.

Current impact of viral hepatitis on liver cancer development: The challenge remains

Chronic infections due to hepatitis B and hepatitis C viruses are responsible for most cases of hepatocellular carcinoma (HCC) worldwide, and this association is likely to remain during the next decade. Moreover, viral hepatitis-related HCC imposes an important burden on public health in terms of disability-adjusted life years. In order to reduce such a burden, some major challenges must be faced. Universal vaccination against hepatitis B virus, especially in the neonatal period, is probably the most relevant primary preventive measure against the development of HCC. Moreover, considering the large adult population already infected with hepatitis B and C viruses, it is also imperative to identify these individuals to ensure their access to treatment. Both hepatitis B and C currently have highly effective therapies, which are able to diminish the risk of development of liver cancer. Finally, it is essential for individuals at high-risk of HCC to be included in surveillance programs, so that tumors are detected at an early stage. Patients with hepatitis B or C and advanced liver fibrosis or cirrhosis benefit from being followed in a surveillance program. As hepatitis B virus is oncogenic and capable of leading to liver cancer even in individuals with early stages of liver fibrosis, other high-risk groups of patients with hepatitis B are also candidates for surveillance. Considerable effort is required concerning these strategies in order to decrease the incidence and the mortality of viral hepatitis-related HCC.

Novel Biomarkers of Hepatitis B Virus and Their Use in Chronic Hepatitis B Patient Management

Even though an approved vaccine for hepatitis B virus (HBV) is available and widely used, over 257 million individuals worldwide are living with chronic hepatitis B (CHB) who require monitoring of treatment response, viral activity, and disease progression to reduce their risk of HBV-related liver disease. There is currently a lack of predictive markers to guide clinical management and to allow treatment cessation with reduced risk of viral reactivation. Novel HBV biomarkers are in development in an effort to improve the management of people living with CHB, to predict disease outcomes of CHB, and further understand the natural history of HBV. This review focuses on novel HBV biomarkers and their use in the clinical setting, including the description of and methodology for quantification of serum HBV RNA, hepatitis B core-related antigen (HBcrAg), quantitative hepatitis B surface antigen (qHBsAg), including ultrasensitive HBsAg detection, quantitative anti-hepatitis B core antigen (qAHBc), and detection of HBV nucleic acid-related antigen (HBV-NRAg). The utility of these biomarkers in treatment-naïve and treated CHB patients in several clinical situations is further discussed. Novel HBV biomarkers have been observed to provide critical clinical information and show promise for improving patient management and our understanding of the natural history of HBV.

Entecavir add-on Peg-interferon therapy plays a positive role in reversing hepatic fibrosis in treatment-naïve chronic hepatitis B patients: a prospective and randomized controlled trial

BACKGROUND

The efficacy of entecavir (ETV) add-on peg-interferon therapy compared with ETV monotherapy in treatment-naïve hepatitis B virus (HBV) patients remains controversial. We investigated whether adding peg-interferon to ongoing ETV treatment leads to a better curative effect or not.

METHODS

All patients have been recruited between August 2013 and January 2015 from the Shanghai Public Health Clinical Center and Zhongshan Hospital (China). Eligible HBV patients (n = 144) were randomly divided (1:1) to receive either ETV monotherapy (n = 70) or peg-interferon add-on therapy from week 26 to 52 (n = 74). Patients were followed-up for at least 2 years. Indexes including hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) seroconversion rate, sustained virologic response, transient elastography value, and histological scores were evaluated every 3 months until the end of the study. The rate of patients with HBsAg loss was defined as the primary endpoint criteria.

RESULTS

At week 26, no patient achieved HBsAg seroconversion in either group. At week 52, one patient in the monotherapy group was HBsAg-negative but there was none in the combination therapy group. The monotherapy group showed significantly better liver function recovery results than the combination therapy group. At week 78, one patient in the combination group had HBsAg seroconverted. At week 104, only three patients in the combination therapy group were HBsAg-negative compared with one patient in monotherapy. The mean alanine aminotransferase and aspartate aminotransferase levels and transient elastography values decreased significantly compared with baseline. Both groups showed a favorable decrease in alpha-fetoprotein (monotherapy: 4.5 [2.8, 7.1] vs. 2.2 [1.8, 3.1] ng/mL, P < 0.001; combination therapy: 5.7 [3.0, 18.8] vs. 3.2 [2.0, 4.3] ng/mL, P < 0.001) and an improved result of liver biopsy examination scores. The combination group showed a better improvement in histology compared with the monotherapy group (mean transient elastography value 6.6 [4.9, 9.8] vs. 7.8 [5.4, 11.1] kPa, P = 0.028). But there was no significant difference in HBsAg conversion rate (1.8% [1/56] vs. 4.1% [3/73], P = 0.809) and HBeAg conversion rate (12.5% [7/56] vs. 11.0% [8/73], P = 0.787), as well as HBV-DNA, sustained virologic response (93.2% vs. 98.5%, P = 0.150) between the two groups.

CONCLUSIONS

Both therapies supported liver function recovery and histology improvement. Combination therapy did not show better anti-viral efficacy in HBsAg or HBeAg seroconversion compared with monotherapy. However, combination therapy played a more positive role in reversing hepatic fibrosis compared with monotherapy.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02849132; https://clinicaltrials.gov/ct2/show/NCT02849132.

CD4+ T Cells in Chronic Hepatitis B and T Cell-Directed Immunotherapy

The impaired T cell responses observed in chronic hepatitis B (HBV) patients are considered to contribute to the chronicity of the infection. Research on this impairment has been focused on CD8⁺ T cells because of their cytotoxic effector function; however, CD4⁺ T cells are crucial in the proper development of these long-lasting effector CD8⁺ T cells. In this review, we summarize what is known about CD4⁺ T cells in chronic HBV infection and discuss the importance and opportunities of including CD4⁺ T cells in T cell-directed immunotherapeutic strategies to cure chronic HBV.

A short note on HBV infection

HBV-related liver sickness or hepatocellular carcinoma is common worldwide. Therefore, it is of interest to document the current trends in hepatitis prevention, diagnosis, treatment and care.

Genome-wide Association Study Identifies Genetic Variants Associated With Early and Sustained Response to (Pegylated) Interferon in Chronic Hepatitis B Patients: The GIANT-B Study

Background

(Pegylated) Interferon ([Peg]IFN) therapy leads to response in a minority of chronic hepatitis B (CHB) patients. Host genetic determinants of response are therefore in demand.

Methods

In this genome-wide association study (GWAS), CHB patients, treated with (Peg)IFN for at least 12 weeks ± nucleos(t)ide analogues within randomized trials or as standard of care, were recruited at 21 centers from Europe, Asia, and North America. Response at 24 weeks after (Peg)IFN treatment was defined as combined hepatitis B e antigen (HBeAg) loss with hepatitis B virus (HBV) DNA <2000 IU/mL, or an HBV DNA <2000 IU/mL for HBeAg-negative patients.

Results

Of 1144 patients, 1058 (92%) patients were included in the GWAS analysis. In total, 282 (31%) patients achieved the response and 4% hepatitis B surface antigen (HBsAg) loss. GWAS analysis stratified by HBeAg status, adjusted for age, sex, and the 4 ancestry components identified PRELID2 rs371991 (B= −0.74, standard error [SE] = 0.16, P = 3.44 ×10^–6) for HBeAg-positive patients. Importantly, PRELID2 was cross-validated for long-term response in HBeAg-negative patients. G3BP2 rs3821977 (B = 1.13, SE = 0.24, P = 2.46 × 10^–6) was associated with response in HBeAg-negative patients. G3BP2 has a role in the interferon pathway and was further examined in peripheral blood mononuclear cells of healthy controls stimulated with IFNα and TLR8. After stimulation, less production of IP-10 and interleukin (IL)-10 proteins and more production of IL-8 were observed with the G3BP2 G-allele.

Conclusions

Although no genome-wide significant hits were found, the current GWAS identified genetic variants associated with (Peg)IFN response in CHB. The current findings could pave the way for gene polymorphism-guided clinical counseling, both in the setting of (Peg)IFN and the natural history, and possibly for new immune-modulating therapies.

Clinical Trials Registation

NCT01401400.

Transcriptome alterations in HepG2 cells induced by shRNA knockdown and overexpression of TMEM2 gene

Transmembrane 2 (TMEM2) gene inhibits chronic hepatitis-B virus (HBV) infection, while the underlying molecular mechanisms remain unknown. Transcriptome alterations in HepG2 cells following TMEM2 overexpression or silencing by shRNA were analyzed by next-generation sequencing. Both overexpression and knockdown of the TMEM2 gene caused wide-spread changes in gene expression in HepG2 cells. Differentially expressed genes caused by altered TMEM2 gene expression were associated with multiple biological processes linked with viral infection and various signaling pathways. KEGG analysis revealed that many of the differentially expressed genes were enriched in the PI3K/AKT signaling pathway. Moreover, we show that genes related to the PI3K/AKT signaling pathway, such as SYK, FLT4, AKT3, FLT1, and IL6, are biological targets regulated by TMEM2 in HepG2 cells. This is the first transcriptome-wide study in which TMEM2-regulated genes in HepG2 cells have been screened. Our findings elucidate the molecular events associated with TMEM2-mediated hepatocyte pathogenesis in chronic HBV infection.

Reasons to consider early treatment in chronic hepatitis B patients

In spite of a decrease in the prevalence and incidence seen in recent years, chronic hepatitis B (CHB) still remains a major healthcare challenge, prevalent mostly in developing but also in developed regions. CHB is associated with significant morbidity and mortality, secondary to the complications of disease progression; cirrhosis and hepatocellular carcinoma (HCC). Historically, antiviral treatment has been restricted to patients with active hepatitis, established liver disease, fibrosis or cirrhosis and/or the risk of HCC development. As a result, patients with hepatitis B 'e' antigen (HBeAg) -positive chronic infection, formerly referred to as the 'immune tolerant' disease phase, have been excluded from treatment, since immune tolerant CHB had been considered 'benign' with no ostensible progressive liver disease. However, recent advances in 'decoding' the immunopathogenesis of CHB challenged the accuracy of this classical perception: it is now well-recognised that HBeAg-positive chronic infection is not characterized by immunological tolerance and that events associated with tumourigenesis are already present during this early disease phase. These findings have led to a paradigm shift: in 2017, the European Association for the Study of the Liver (EASL) recommended a change in the nomenclature and clinical categorisation of CHB and proposed lowering the threshold for antiviral treatment to include patients with HBeAg-positive chronic infection. It is anticipated that this could delay or even prevent disease progression and the development of HCC, alongside the potential to achieve functional cure (hepatitis B 'surface' antigen loss with or without development of hepatitis B 'surface' antibody). The current article reviews relevant literature and discusses the reasons for considering early treatment in CHB.

Conservative Evolution of Hepatitis B Virus Precore and Core Gene During Immune Tolerant Phase in Intrafamilial Transmission

Hepatitis B virus (HBV) is characterized with high mutations, which is attributed to the lack of proof-reading of the viral reverse transcriptase and host immune pressure. In this study, 31 HBV chronic carriers from 14 families were enrolled to investigate the evolution of the same original HBV sources in different hosts. Sequences of pre-C and C (pre-C/C) genes were analyzed in eight pairs of HBV-infected mothers with longitudinal sera (at an interval of 6.0-7.2 years) and their children (5.5-6.7 years old), and in 15 adults (21-78 years old) from six families with known intrafamilial HBV infection. The pre-C/C sequences had almost no change in eight mothers during 6.0-7.2 years and their children who were in immune tolerant phase. The pre-C/C sequences from the 15 adults of six families, mostly in the immune-clearance phase or the low replicative phase, showed various diversified mutations between individuals from each family. Compared to a reference stain (GQ205441) isolated nearby, the pre-C/C in individuals in immune tolerant phase showed 98.56%-99.52% homology at nucleotide level and 99.5%-100% homology at amino acid level. In contrast, multiple mutations were developed in the immune-clearance phase or the low replicative phase, affecting immune epitopes in core gene and G1896 in pre-C gene. The results indicate that the evolution of new HBV variants is not mainly resulted from the spontaneous error rate of viral reverse transcription, but from the host immune pressure.

Review article: clinical pharmacology of current and investigational hepatitis B virus therapies

BACKGROUND

Treatment of hepatitis B virus (HBV) infection with current therapy suppresses HBV DNA, but loss of hepatitis B surface antigen (HBsAg; functional cure), is rare. Multiple compounds are under investigation.

AIMS

To describe the pharmacology, including drug interactions, efficacy, safety and mechanisms of action of investigational compounds for HBV infection.

METHODS

Descriptive review using PubMed and Google to identify literature/conference papers on investigational compounds (≥Phase 2) with data on efficacy and safety in HBV-infected patients.

RESULTS

Bulevirtide, JNJ-56136379, ABI-H0731, REP-2139, and inarigivir decrease HBV DNA/RNA, with greater potency than current nucleos(t)ide analogues. REP-2139 (25%-75% of patients, 20-48 weeks treatment) and inarigivir (26% of patients, 12-24 weeks treatment) induce HBsAg loss. ARO-HBV reduced (>1.5 log₁₀ UI/mL) HBsAg in 85% of patients (12 weeks treatment). There are some safety concerns with investigational agents (e.g., increased bile acids with bulevirtide, and liver enzyme flares with REP-2139) which will require a risk benefit assessment compared with current therapies. Single and multidose pharmacokinetic data are available for bulevirtide, JNJ-56136379, ABI-H0731; no such data are available for REP-2139, ARO-HBV, inarigivir. Initial drug interaction assessments have been performed with bulevirtide and inarigivir (only in vitro).

CONCLUSIONS

There are promising investigational therapies for HBV infection. Increasing the potential for HBsAg loss may result in more patients achieving functional cure. However, many knowledge gaps remain such as pharmacokinetics in those with HBV, cirrhosis and renal impairment but also the interaction potential between investigational therapies, risk-benefit profiles, and potential for drug interactions with medications used to treat comorbidities associated with aging.

Identification of key genes and pathways associated with different immune statuses of hepatitis B virus infection

We aimed to identify key genes and pathways associated with different immune statuses of hepatitis B virus (HBV) infection. The gene expression and DNA methylation profiles were analysed in different immune statuses of HBV infection. Differentially expressed genes (DEGs) and differentially methylated genes (DMGs) were identified, followed by their functional and integrative analyses. The differential expression of IgG Fc receptors (FcγRs) in chronic HBV-infected patients and immune cells during different stages of HBV infection was investigated. Toll-like receptor (TLR) signalling pathway (including TLR6) and leucocyte transendothelial migration pathway (including integrin subunit beta 1) were enriched during acute infection. Key DEGs, such as FcγR Ib and FcγR Ia, and interferon-alpha inducible protein 27 showed correlation with alanine aminotransferase levels, and they were differentially expressed between acute and immune-tolerant phases and between immune-tolerant and immune-clearance phases. The integrative analysis of DNA methylation profile showed that lowly methylated and highly expressed genes, including cytotoxic T lymphocyte-associated protein 4 and mitogen-activated protein kinase 3 were enriched in T cell receptor signalling pathway during acute infection. Highly methylated and lowly expressed genes, such as Ras association domain family member 1 and cyclin-dependent kinase inhibitor 2A were identified in chronic infection. Furthermore, differentially expressed FcγR Ia, FcγR IIa and FcγR IIb, CD3^- CD56⁺ CD16⁺ natural killer cells and CD14^high CD16⁺ monocytes were identified between immune-tolerant and immune-clearance phases by experimental validation. The above genes and pathways may be used to distinguish different immune statuses of HBV infection.

Immune-Escape Hepatitis B Virus Mutations Associated with Viral Reactivation upon Immunosuppression

Hepatitis B virus (HBV) reactivation occurs as a major complication of immunosuppressive therapy among persons who have recovered from acute hepatitis and those who have controlled chronic infection. Recent literature data emphasize the presence of a high degree of S gene variability in HBV isolates from patients who developed reactivation. In reactivated HBV, the most frequently detected mutations belong to the second loop of “a” determinant in HBsAg. These mutations were identified to be immune escape and responsible for vaccine- and diagnostic-escape phenomena. Their emergence clearly provides survival in the presence of a developed humoral immune response and is often associated with impaired serological diagnosis of HBV reactivation. The knowledge of their existence and roles can elucidate the process of reactivation and strongly highlights the importance of HBV DNA detection in monitoring all patients with a history of HBV infection who are undergoing immunosuppression. This review discusses the possible influence of the most frequently found immune-escape mutations on HBV reactivation.

Immune network for viral hepatitis B: Topological representation

The liver is a well-known immunotolerogenic environment, which provides the adequate setting for liver infectious pathogens persistence such as the hepatitis B virus (HBV). Consequently, HBV infection can derive in the development of chronic disease in a proportion of the patients. If this situation persists in time, chronic hepatitis B (CHB) would end in cirrhosis, hepatocellular carcinoma and eventually, the death of the patient. It is thought that this immunotolerogenic environment is the result of complex interactions between different elements of the immune system and the viral biology. Therefore, the purpose of this work is to unravel the mechanisms implied in the development of CHB and to design a tool able to help in the study of adequate therapies. Firstly, a conceptual framework with the main components of the immune system and viral dynamics was constructed providing an overall insight on the pathways and interactions implied in this disease. Secondly, a review of the literature was performed in a modular fashion: (i) viral dynamics, (ii) innate immune response, (iii) humoral and (iv) cellular adaptive immune responses and (v) tolerogenic aspects. Finally, the information collected was integrated into a single topological representation that could serve as the plan for the systems pharmacology model architecture. This representation can be considered as the previous unavoidable step to the construction of a quantitative model that could assist in biomarker and target identification, drug design and development, dosing optimization and disease progression analysis.

Human Hepatitis B Virus Core Protein Inhibits IFNα-Induced IFITM1 Expression by Interacting with BAF200

Human hepatitis B virus core protein (HBc) is a structural protein of the hepatitis B virus (HBV) and contributes to HBV regulation of host-cell transcription. However, the mechanisms of transcriptional regulation remain poorly characterized. To dissect the function of HBc, a yeast two-hybrid was performed to identify HBc-binding proteins, and the C-terminal of BRG1/hBRM-associated factors 200 (BAF200C) was identified. Then, the existence of HBc interactions with BAF200C and full-length BAF200 was confirmed via co-immunoprecipitation assays in 293T, HepG2 and HepG2-NTCP cells. Furthermore, we show that the binding between HBc and BAF200 was of vital importance to HBc mediated downregulation of interferon-induced transmembrane protein 1 (IFITM1) expression, and the mechanisms for the downregulation were disclosed as follows. Basal level of IFITM1 expression depends on BAF200, rather than the JAK–STAT1 pathway. The interaction of HBc with BAF200 disturbs the stability of the polybromo-associated BAF (PBAF) complex and results in the suppression of IFTM1 transcription. Finally, the antiviral effects of IFITM1 on cell proliferation and HBV replication were found to be partially restored when HBc was co-transfected with BAF200. Collectively, our findings indicate that HBc plays a role in HBV resistance against the antiviral activities of IFNα, providing details about HBV evasion of host innate immunity.

Correlation between serum Hcy level and severity of chronic HBV hepatitis

Objective The aim of this work was to investigate the serum homocysteine (Hcy) level and severity of hepatitis B virus (HBV).

Methods 72 patients with chronic HBV and 28 healthy controls were included in this work. Of the included 72 chronic HBV hepatitis patients, 20 patients had mild disease, 31 had moderate disease and 21 had severe disease. The serum homocysteine (Hcy), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBIL) were examined in both HBV hepatitis and control patients.

Results Significant statistical difference was observed for serum Hcy, ALT, AST and TBIL in different groups (p<0.05). The serum Hcy, ALT, AST and TBIL in the severe group were significantly higher than those of other groups with statistical difference (p<0.05); significant correlation was observed between serum Hcy and AST in the moderate (r=0.43, p<0.05) and severe disease groups (r=0.63, p<0.05). However, the correlation between Hcy and ALT, and Hcy andTBIL were not statistically significant in any group (p>0.05).

Conclusion The serum Hcy level in patients with hepatitis B reflects the damage to the of liver. The continuous increase of serum Hcy level can be regarded as a risk factor for the progression of hepatitis, and it can be used as serological marker for clinical diagnosis, treatment and prognosis.

Elevated interleukin-35 suppresses liver inflammation by regulation of T helper 17 cells in acute hepatitis B virus infection

Interleukin (IL)-35 is a responsive anti-inflammatory cytokine implicated in different diseases processes. It has been reported that elevated IL-35 contributed to immunosuppression in chronic hepatitis by modulation of T helper 17 (Th17) and regulatory T cells. However, the role of IL-35 in acute hepatitis B (AHB) was still not completely elucidated. Thus, in the present study, we analyzed the expression and regulatory activity of IL-35 to Th17 cells and inflammatory response during acute hepatitis B virus (HBV) infection in both peripheral blood cells isolated from AHB patients and in hydrodynamic induced HBV-infected mouse model. Plasma IL-35 level and circulating HBV peptides-induced Th17 frequency was significantly elevated in AHB patients, and IL-35 expression negatively correlated with liver inflammation. In vitro IL-35 stimulation to CD4+ T cells purified from AHB patients down-regulated HBV peptides-induced Th17-phenotype, which presented as reduced IL-17 and IL-22 production. In vivo IL-35 administration dampened liver inflammation in HBV plasmid injected mice, however, did not affect HBV antigens production. This process was accompanied by suppression of natural killer cells and down-regulation of HBV peptides-induced Th17 cells in the liver, but did not affect total intrahepatic lymphocytes and other cell subsets numbers or chemokines expression in the liver. In conclusion, the current data indicated that IL-35 might be a novel mediator associated with hepatocytes damage and liver inflammation by regulating HBV peptides-induced Th17 cells during acute HBV infection. The potential anti-inflammatory property of IL-35 might be pivotal for developing new therapeutic approaches for hepatitis B.

Persistent Replication of HIV, Hepatitis C Virus (HCV), and HBV Results in Distinct Gene Expression Profiles by Human NK Cells

Natural killer (NK) cells during chronic viral infection have been well studied in the past. We performed an unbiased next-generation RNA-sequencing approach to identify commonalities or differences of the effect of HIV, HCV, and HBV viremia on NK cell transcriptomes. Using cell sorting, we obtained CD3^- CD56⁺ NK cells from blood of 6 HIV-, 8 HCV-, and 32 HBV-infected patients without treatment. After library preparation and sequencing, we used an in-house analytic pipeline to compare expression levels with matched healthy controls. In NK cells from HIV-, HCV-, and HBV-infected patients, transcriptome analysis identified 272, 53, and 56 differentially expressed genes, respectively (fold change, >1.5; q-value, 0.2). Interferon-stimulated genes were induced in NK cells from HIV/HCV patients, but not during HBV infection. HIV viremia downregulated ribosome assembly genes in NK cells. In HBV-infected patients, viral load and alanine aminotransferase (ALT) variation had little effect on genes related to NK effector function. In conclusion, we compare, for the first time, NK cell transcripts of viremic HIV, HCV, and HBV patients. We clearly demonstrate distinctive NK cell gene signatures in three different populations, suggestive for a different degree of functional alterations of the NK cell compartment compared to healthy individuals.IMPORTANCE Three viruses exist that can result in persistently high viral loads in immunocompetent humans: human immunodeficiency virus (HIV), hepatitis C virus, and hepatitis B virus. In the last decades, by using flow cytometry and in vitro assays on NK cells from patients with these types of infections, several impairments have been established, particularly during and possibly contributing to HIV viremia. However, the background of NK cell impairments in viremic patients is not well understood. In this study, we describe the NK cell transcriptomes of patients with high viral loads of different etiologies. We clearly demonstrate distinctive NK cell gene signatures with regard to interferon-stimulated gene induction and the expression of genes coding for activation markers or proteins involved in cytotoxic action, as well immunological genes. This study provides important details necessary to uncover the origin of functional and phenotypical differences between viremic patients and healthy subjects and provides many leads that can be confirmed using future in vitro manipulation experiments.

A global scientific strategy to cure hepatitis B

Chronic hepatitis B virus (HBV) infection is a global public health challenge on the same scale as tuberculosis, HIV, and malaria. The International Coalition to Eliminate HBV (ICE-HBV) is a coalition of experts dedicated to accelerating the discovery of a cure for chronic hepatitis B. Following extensive consultation with more than 50 scientists from across the globe, as well as key stakeholders including people affected by HBV, we have identified gaps in our current knowledge and new strategies and tools that are required to achieve HBV cure. We believe that research must focus on the discovery of interventional strategies that will permanently reduce the number of productively infected cells or permanently silence the covalently closed circular DNA in those cells, and that will stimulate HBV-specific host immune responses which mimic spontaneous resolution of HBV infection. There is also a pressing need for the establishment of repositories of standardised HBV reagents and protocols that can be accessed by all HBV researchers throughout the world. The HBV cure research agenda outlined in this position paper will contribute markedly to the goal of eliminating HBV infection worldwide.

Gene expression profiling of human tissue-resident immune cells: Comparing blood and liver

In this study, we describe a method to reliably characterize intrahepatic leukocyte populations using flow cytometry and next‐generation RNA sequencing on fresh human liver biopsies. Over the last decades, immune responses of viral hepatitis patients, and of other liver diseases, have been incompletely characterized. Most studies include peripheral blood samples only, foregoing the possibility to investigate the site of inflammation directly. Here, we show that with an optimized protocol that combines cell sorting and RNA sequencing, we can perform a side by side comparison of both intrahepatic and peripheral immune cells. Using core liver biopsies from chronic hepatitis B virus patients, we show that the expression levels of IFN‐stimulated genes and leukocyte‐specific genes are markedly different in the liver compartment as compared to the peripheral blood. These observations emphasize the need to sample the liver directly. The variation of gene expression profiles in these chronic hepatitis B patients was considerable, despite the uniform treatment with nucleotide analogs and absence of liver inflammation in these patients. Finally, we show that this method can provide a detailed characterization of previously undetected liver‐specific effects of novel candidate therapeutic compounds.

Chronic hepatitis B virus infection

Chronic hepatitis B virus infection is a global public health threat that causes considerable liver-related morbidity and mortality. It is acquired at birth or later via person-to-person transmission. Vaccination effectively prevents infection and chronic hepatitis B virus carriage. In chronically infected patients, an elevated serum hepatitis B virus DNA concentration is the main risk factor for disease progression, although there are other clinical and viral parameters that influence disease outcomes. In addition to liver biochemistry, virological markers, and abdominal ultrasonography, non-invasive assessment of liver fibrosis is emerging as an important assessment modality. Long-term nucleos(t)ide-analogue therapy is safe and well tolerated, achieves potent viral suppression, and reduces the incidence of liver-related complications. However, a need to optimise management remains. Promising novel therapies are at the developmental stage. With current vaccines, therapies, and an emphasis on improving linkage to care, WHO's goal of eliminating hepatitis B virus as a global health threat by 2030 is achievable.

A STAT4 variant increases liver fibrosis risk in Caucasian patients with chronic hepatitis B

BACKGROUND

Host genetic modifiers of the natural history of chronic hepatitis B (CHB) remain poorly understood. Recently, a genome-wide association study (GWAS)-identified polymorphism in the STAT4 gene that contributes to the risk for hepatocellular carcinoma (HCC) was shown to be associated with the full spectrum of hepatitis B virus (HBV) outcomes in Asian patients. However, the functional mechanisms for this effect are unknown and the role of the variant in modulating HBV disease in Caucasians has not been investigated.

AIMS

To determine whether STAT4 genetic variation is associated with liver injury in Caucasian patients with CHB and to investigate potential mechanisms mediating this effect.

METHODS

STAT4 rs7574865 was genotyped in 1085 subjects (830 with CHB and 255 healthy controls). STAT4 expression in liver, PBMCs and NK cells, STAT4 phosphorylation and secretion of interferon-gamma (IFN-γ) according to STAT4 genetic variation was examined.

RESULTS

STAT4 rs7574865 genotype was independently associated with hepatic inflammation (OR: 1.42, 95% CI: 1.07-2.06, P = 0.02) and advanced fibrosis (OR: 1.83, 95% CI: 1.19-2.83, P = 0.006). The minor allele frequency of rs7574865 was significantly lower than that in healthy controls. rs7574865 GG risk carriers expressed lower levels of STAT4 in liver, PBMCs and in NK cells, while NK cells from patients with the risk genotype had impaired STAT4 phosphorylation following stimulation with IL-12/IL-18 and a reduction in secretion of IFN-γ.

CONCLUSION

Genetic susceptibility to HBV persistence, hepatic inflammation and fibrosis in Caucasians associates with STAT4 rs7574865 variant. Downstream effects on NK cell function through STAT4 phosphorylation-dependent IFN-γ production likely contribute to these effects.

Antiviral effect of hepatitis B virus S gene-specific anti-gene locked nucleic acid in hepatitis B virus transgenic mice

AIM

To investigate the antiviral effect of hepatitis B virus (HBV) S gene-specific anti-gene locked nucleic acid (LNA) in transgenic mice.

METHODS

Thirty HBV transgenic mice were randomly divided into 5 groups (n = 6 each): blank control group, negative control group (unrelated sequence), lamivudine group, antisense-LNA treatment group, and anti-gene LNA treatment group. LNA was injected into transgenic mice via the tail vein, and lamivudine was given by gavage. Serum HBV DNA was tested by real-time PCR; serum hepatitis B surface antigen (HBsAg) was determined by ELISA; the mRNA level of HBV S gene was detected by RT-PCR; and the positive rate of HBsAg in liver cells was detected by immunohistochemistry.

RESULTS

On 3, 5, and 7 d after anti-gene LNA treatment, HBV DNA was reduced by 37.18%, 50.27%, and 61.46%, respectively, and HBsAg was reduced by 30.17%, 44%, and 57.76%, respectively; there was a significant difference in HBV DNA and HBsAg compared with those before administration (P < 0.05) or compared with control groups (blank control, negative control, lamivudine, and antisense-LNA) (P < 0.05). The mRNA level of HBV S gene (0.33) and the HBsAg positive rate of liver cells (31%) were significantly reduced compared with control groups (P < 0.05). The function of liver and kidney tests and tissue HE staining showed no abnormal changes.

CONCLUSION

Anti-gene LNA targeting the S gene has a strong inhibitory effect on HBV replication and expression in HBV transgenic mice, and this provides experimental basis for gene therapy of HBV.