Hepatitis B Virus Adaptation to the CD8+ T Cell Response: Consequences for Host and Pathogen

Joint host-pathogen genomic analysis identifies hepatitis B virus mutations associated with human NTCP and HLA class I variation

Evolutionary changes in the hepatitis B virus (HBV) genome could reflect its adaptation to host-induced selective pressure. Leveraging paired human exome and ultra-deep HBV genome-sequencing data from 567 affected individuals with chronic hepatitis B, we comprehensively searched for the signatures of this evolutionary process by conducting "genome-to-genome" association tests between all human genetic variants and viral mutations. We identified significant associations between an East Asian-specific missense variant in the gene encoding the HBV entry receptor NTCP (rs2296651, NTCP S267F) and mutations within the receptor-binding region of HBV preS1. Through in silico modeling and in vitro preS1-NTCP binding assays, we observed that the associated HBV mutations are in proximity to the NTCP variant when bound and together partially increase binding affinity to NTCP S267F. Furthermore, we identified significant associations between HLA-A variation and viral mutations in HLA-A-restricted T cell epitopes. We used in silico binding prediction tools to evaluate the impact of the associated HBV mutations on HLA presentation and observed that mutations that result in weaker binding affinities to their cognate HLA alleles were enriched. Overall, our results suggest the emergence of HBV escape mutations that might alter the interaction between HBV PreS1 and its cellular receptor NTCP during viral entry into hepatocytes and confirm the role of HLA class I restriction in inducing HBV epitope variations.

Recent advances in understanding T cell activation and exhaustion during HBV infection

Chronic hepatitis B virus (HBV) infection remains a major public health concern globally, and T cell responses are widely believed to play a pivotal role in mediating HBV clearance. Accordingly, research on the characteristics of HBV-specific T cell responses, from activation to exhaustion, has advanced rapidly. Here, we summarize recent developments in characterizing T cell immunity in HBV infection by reviewing basic and clinical research published in the last five years. We provide a comprehensive summary of the mechanisms that induce effective anti-HBV T cell immunity, as well as the latest developments in understanding T cell dysfunction in chronic HBV infection. Furthermore, we briefly discuss current novel treatment strategies aimed at restoring anti-HBV T cell responses.

Japanese Encephalitis Vaccine Generates Cross-Reactive Memory T Cell Responses to Zika Virus in Humans

Objective. Zika virus (ZIKV) and Japanese encephalitis virus (JEV) are mosquito-borne flaviviruses with sequence homology. ZIKV circulates in some regions where JEV also circulates, or where JE vaccination is used. Cross-immunity between flaviviruses exists, but the precise mechanisms remain unclear. We previously demonstrated that T cell immunity induced by the live-attenuated Japanese encephalitis (JE) SA14-14-2 vaccine conferred protective immunity against ZIKV infection in mice, which could even bypass antibody-dependent enhancement. However, the role of T cell immune, especially memory T cell subsets, in cross-reactive immune responses between JE vaccine and ZIKV in humans has not been reported. Methods. We examined central and effector memory CD4+ and CD8+ T cell (TCM and TEM) responses (including degranulation, cytokines, and chemokines) in the presence of JEV and ZIKV, respectively, by using qualified peripheral blood mononuclear cell samples from 18 children who had recently received a two-dose course of JE vaccine SA14-14-2 as well as seven children without JE vaccination. Results. Cross-reactive CD8+ TCM in response to ZIKV was characterized by secretion of IFN-γ, whereas CD8+ TEM did not show significant upregulation of functional factors. In the presence of ZIKV, IFN-γ and TNF-α expression was upregulated by CD4+ TEM, and the expression signature of CD4+ TCM is more cytotoxic potential. Conclusions. We profiled the cross-reactive memory T cell responses to ZIKV in JE vaccine recipients. These data will provide evidence for the mechanism of cross-reactive memory T cell immune responses between JEV and ZIKV and a more refined view of bivalent vaccine design strategy.

Hepatitis B functional cure and immune response

Hepatitis B virus (HBV) is a hepatotropic virus, which damage to hepatocytes is not direct, but through the immune system. HBV specific CD4⁺ T cells can induce HBV specific B cells and CD8⁺ T cells. HBV specific B cells produce antibodies to control HBV infection, while HBV specific CD8⁺ T cells destroy infected hepatocytes. One of the reasons for the chronicity of HBV infection is that it cannot effectively activate adoptive immunity and the function of virus specific immune cells is exhausted. Among them, virus antigens (including HBV surface antigen, e antigen, core antigen, etc.) can inhibit the function of immune cells and induce immune tolerance. Long term nucleos(t)ide analogues (NAs) treatment and inactive HBsAg carriers with low HBsAg level may "wake up" immune cells with abnormal function due to the decrease of viral antigen level in blood and liver, and the specific immune function of HBV will recover to a certain extent, thus becoming the "dominant population" for functional cure. In turn, the functional cure will further promote the recovery of HBV specific immune function, which is also the theoretical basis for complete cure of hepatitis B. In the future, the complete cure of chronic HBV infection must be the combination of three drugs: inhibiting virus replication, reducing surface antigen levels and specific immune regulation, among which specific immunotherapy is indispensable. Here we review the relationship, mechanism and clinical significance between the cure of hepatitis B and immune system.

Heterogeneity of immune control in chronic hepatitis B virus infection: Clinical implications on immunity with interferon-α treatment and retreatment

Hepatitis B virus (HBV) infection is a global public health issue. Interferon-α (IFN-α) treatment has been used to treat hepatitis B for over 20 years, but fewer than 5% of Asians receiving IFN-α treatment achieve functional cure. Thus, IFN-α retreatment has been introduced to enhance antiviral function. In recent years, immune-related studies have found that the complex interactions between immune cells and cytokines could modulate immune response networks, in-cluding both innate and adaptive immunity, triggering immune responses that control HBV replication. However, heterogeneity of the immune system to control HBV infection, particularly HBV-specific CD8⁺ T cell heterogeneity, has consequ-ential effects on T cell-based immunotherapy for treating HBV infection. Altogether, the host’s genetic variants, negative-feedback regulators and HBV components affecting the immune system's ability to control HBV. In this study, we reviewed the literature on potential immune mechanisms affecting the immune control of HBV and the clinical effects of IFN-α treatment and retreatment.

Spacer Domain in Hepatitis B Virus Polymerase: Plugging a Hole or Performing a Role?

Hepatitis B virus (HBV) polymerase is divided into terminal protein, spacer, reverse transcriptase, and RNase domains. Spacer has previously been considered dispensable, merely acting as a tether between other domains or providing plasticity to accommodate deletions and mutations. We explore evidence for the role of spacer sequence, structure, and function in HBV evolution and lineage, consider its associations with escape from drugs, vaccines, and immune responses, and review its potential impacts on disease outcomes.

HAMdetector: A Bayesian regression model that integrates information to detect HLA-associated mutations

MOTIVATION

A key process in anti-viral adaptive immunity is that the Human Leukocyte Antigen system (HLA) presents epitopes as Major Histocompatibility Complex I (MHC I) protein-peptide complexes on cell surfaces and in this way alerts CD8+ cytotoxic T-Lymphocytes (CTLs). This pathway exerts strong selection pressure on viruses, favoring viral mutants that escape recognition by the HLA/CTL system. Naturally, such immune escape mutations often emerge in highly variable viruses, e.g. HIV or HBV, as HLA-associated mutations (HAMs), specific to the hosts MHC I proteins. The reliable identification of HAMs is not only important for understanding viral genomes and their evolution, but it also impacts the development of broadly effective anti-viral treatments and vaccines against variable viruses. By their very nature, HAMs are amenable to detection by statistical methods in paired sequence/HLA data. However, HLA alleles are very polymorphic in the human host population which makes the available data relatively sparse and noisy. Under these circumstances, one way to optimize HAM detection is to integrate all relevant information in a coherent model. Bayesian inference offers a principled approach to achieve this.

RESULTS

We present a new Bayesian regression model for the detection of HAMs that integrates a sparsity-inducing prior, epitope predictions, and phylogenetic bias assessment, and that yields easily interpretable quantitative information on HAM candidates. The model predicts experimentally confirmed HAMs as having high posterior probabilities, and it performs well in comparison to state-of-the-art models for several data sets from individuals infected with HBV, HDV, and HIV.

AVAILABILITY

The source code of this software is available at https://github.com/HAMdetector/Escape.jl under a permissive MIT license.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

HBV S antigen evolution in the backdrop of HDV infection affects epitope processing and presentation

INTRODUCTION

HBV can evolve under selection pressure exerted by drugs and/or host immunity, resulting in accumulation of escape mutations that can affect the drug or the immune activity. Hepatitis delta virus (HDV) coinfection is also known to exert selection pressure on HBV, which leads to selective amplification of certain mutations, especially in genes that are required for HDV pathogenesis, such as HBsAg. However, little is known about the function of these mutations on HBV or HDV life cycle. The purpose of this study is to determine mutations selectively amplified in the backdrop of HDV, and how these mutations affect processing of CD4- and CD8-T cell epitopes.

METHODS

HBsAg was successfully amplified from 49/50 HBV mono- and 36/50 coinfected samples. The sequences were used to identify mutations specific to each study group, followed by an in silico analysis to determine the effect of these mutations on (1) proteasomal degradation, (2) MHC-I and MHC-II biding, and (3) processing of T-cell epitopes.

RESULTS

HBV-HDV coinfected sequences exhibited certain unique mutations in HBsAg genes. Some of these mutations affected the generation of proteasomal sites, binding of HBsAg epitopes to MHC-I and -II ligands, and subsequent generation of T- cell epitopes.

CONCLUSION

These observations suggest that HBV selectively amplifies certain mutations in the backdrop of HDV coinfection. Selective amplification of these mutations at certain strategic locations might not only enable HBV to counteract the inhibitory effects of HDV on HBV replication but also facilitate its survival by escaping the immune response.

Natural variability in surface antigen and reverse transcriptase domain of hepatitis B virus in treatment-naïve chronic HBV-infected Egyptian patients

Hepatitis B virus (HBV) infection is a serious health problem not only in Egypt, but also worldwide. We collected 57 serum samples from treatment-naïve chronic HBV-infected Egyptians. The DNA segment encoding HBV surface antigen (HBsAg) and reverse transcriptase (RT) domain was partially sequenced. Our data revealed that all viral isolates belonged to genotype D with ayw2 as the predominant serotype (89 %). Regarding HBsAg, 45 substitutions were detected in the collected isolates. Eleven substitutions were found in the major hydrophilic region, including two novel ones (M103T and G130E) that were not correlated before with genotype D. Additionally, 11 occult samples (19 %) were detected, in which the predominant mutations of HBsAg were S143L (7 samples) followed by D144A and T125M (4 samples each). Concerning the RT domain, 26 isolates (45 %) harbored 19 natural mutations that were reported to be associated with antiviral resistance. Eleven different mutations were not correlated previously with genotype D. The most predominant mutation was Y124H (47 samples, 82 %). Interestingly, such mutation was detected in 91 % of the previous reported sequences of HBV isolates collected in Egypt (157 sequences). Furthermore, our study illustrated the presence of viral quasispecies in the HBsAg (10 samples, 17.5 %) and RT domain (9 samples, 15.7 %). In conclusion, we elucidated the presence of natural substitutions in HBsAg and RT domain of HBV isolates obtained from treatment-naïve chronic HBV-infected Egyptian patients. Additionally, we detected viral quasispecies and revealed Y124H as a characteristic substitution in the RT domain for HBV isolates in Egypt. Moreover, novel substitutions in HBsAg and RT domain were reported with genotype D.

IL-35: A Novel Immunomodulator in Hepatitis B Virus-Related Liver Diseases

Chronic hepatitis B virus (HBV) infection is a risk factor for liver cirrhosis (LC) and hepatocellular carcinoma (HCC), however, little is known about the mechanisms involved in the progression of HBV-related diseases. It has been well acknowledged that host immune response was closely related to the clinical outcomes of patients with HBV infection. As the factors closely related to the immunomodulatory process, cytokines are crucial in the cell-cell communication and the host responses to HBV infection. Recently, a newly discovered cytokine, designated as interleukin-35 (IL-35), has been proved to be essential for the progression of chronic HBV infection, the development of cirrhosis, the transformation of cirrhosis to HCC, and the metastasis of HCC. Specifically, it showed various biological activities such as inhibiting the HBV-specific cytotoxic T lymphocyte (CTL) proliferation and cytotoxicity, deactivating the immature effector T-cells (Teffs), as well as delaying the proliferation of dendritic cells. It regulated the immune responses by acting as a “brake” on the activation of Teffs, which subsequently played important roles in the pathogenesis of various inflammatory diseases and malignancies. In this review, we focused on the most recent data on the relationship between IL-35 and chronic HBV infection, LC and HCC.

3D human liver organoids: An in vitro platform to investigate HBV infection, replication and liver tumorigenesis

Hepatitis B Virus (HBV) infection is a leading cause of chronic liver cirrhosis and hepatocellular carcinoma (HCC) with an estimated 400 million people infected worldwide. The precise molecular mechanisms underlying HBV replication and tumorigenesis have remained largely uncharacterized due to the lack of a primary cell model to study HBV, a virus that exhibits stringent host species and cell-type specificity. Organoid technology has recently emerged as a powerful tool to investigate human diseases in a primary 3D cell-culture system that maintains the organisation and functionality of the tissue of origin. In this review, we describe the utilisation of human liver organoid platforms to study HBV. We first present the different categories of liver organoids and their demonstrated ability to support the complete HBV replication cycle. We then discuss the potential applications of liver organoids in investigating HBV infection and replication, related tumorigenesis and novel HBV-directed therapies. Liver organoids can be genetically modified, patient-derived, expanded and biobanked, thereby serving as a clinically-relevant, human, primary cell-derived platform to investigate HBV. Finally, we provide insights into the future applications of this powerful technology in the context of HBV-infection and HCC.

Vaccine-Induced CD8+ T Cell Responses in Children: A Review of Age-Specific Molecular Determinants Contributing to Antigen Cross-Presentation

Infections are most common and most severe at the extremes of age, the young and the elderly. Vaccination can be a key approach to enhance immunogenicity and protection against pathogens in these vulnerable populations, who have a functionally distinct immune system compared to other age groups. More than 50% of the vaccine market is for pediatric use, yet to date vaccine development is often empiric and not tailored to molecular distinctions in innate and adaptive immune activation in early life. With modern vaccine development shifting from whole-cell based vaccines to subunit vaccines also comes the need for formulations that can elicit a CD8⁺ T cell response when needed, for example, by promoting antigen cross-presentation. While our group and others have identified many cellular and molecular determinants of successful activation of antigen-presenting cells, B cells and CD4⁺ T cells in early life, much less is known about the ontogeny of CD8⁺ T cell induction. In this review, we summarize the literature pertaining to the frequency and phenotype of newborn and infant CD8⁺ T cells, and any evidence of induction of CD8⁺ T cells by currently licensed pediatric vaccine formulations. In addition, we review the molecular determinants of antigen cross-presentation on MHC I and successful CD8⁺ T cell induction and discuss potential distinctions that can be made in children. Finally, we discuss recent advances in development of novel adjuvants and provide future directions for basic and translational research in this area.

Hepatocellular carcinoma (HCC): Epidemiology, etiology and molecular classification

Hepatocellular carcinoma (HCC), the primary malignancy of hepatocytes, is a diagnosis with bleak outcome. According to National Cancer Institute's SEER database, the average five-year survival rate of HCC patients in the US is 19.6% but can be as low as 2.5% for advanced, metastatic disease. When diagnosed at early stages, it is treatable with locoregional treatments including surgical resection, Radio-Frequency Ablation, Trans-Arterial Chemoembolization or liver transplantation. However, HCC is usually diagnosed at advanced stages when the tumor is unresectable, making these treatments ineffective. In such instances, systemic therapy with tyrosine kinase inhibitors (TKIs) becomes the only viable option, even though it benefits only 30% of patients, provides only a modest (~3months) increase in overall survival and causes drug resistance within 6months. HCC, like many other cancers, is highly heterogeneous making a one-size fits all option problematic. The selection of liver transplantation, locoregional treatment, TKIs or immune checkpoint inhibitors as a treatment strategy depends on the disease stage and underlying condition(s). Additionally, patients with similar disease phenotype can have different molecular etiology making treatment responses different. Stratification of patients at the molecular level would facilitate development of the most effective treatment option. With the increase in efficiency and affordability of "omics"-level analysis, considerable effort has been expended in classifying HCC at the molecular, metabolic and immunologic levels. This review examines the results of these efforts and the ways they can be leveraged to develop targeted treatment options for HCC.

Plasma Level of ADAMTS13 or IL-12 as an Indicator of HBeAg Seroconversion in Chronic Hepatitis B Patients Undergoing m-ETV Treatment

The ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin motif repeats 13) is a key factor involved in coagulation process and plays a vital role in the progression and prognosis of chronic hepatitis B (CHB) patients with antiviral treatment. However, there are few reports about the profile of plasma ADAMTS13 in CHB patients during entecavir maleate (m-ETV) treatment. One hundred two HBV e antigen (HBeAg)-positive CHB patients on continuous m-ETV naive for at least 96 weeks were recruited. Patients with liver cirrhosis were excluded using liver biopsies and real-time elastography. Plasma ADAMTS13 and interleukin 12 (IL-12) levels were evaluated at baseline and12, 24, 48, 72, and 96 weeks, respectively. The change of ADAMTS13 (ΔADAMTS13) and IL-12 (ΔIL-12) possesses a significant relationship in CHB patients with HBeAg seroconversion (SC) at 48-week m-ETV treatment (p < 0.001), but no significance in patients without SC. Furthermore, Cox multivariate analysis demonstrated that the change of ADAMTS13 (IL-12) is an independent predictor for HBeAg SC at week 96, and the area under the receiver operating characteristic curve for the ΔADAMTS13 (ΔIL-12) in CHB patients with 48-week m- ETV treatment is 0.8204 (0.8354) (p < 0.001, both) to predict HBeAg SC at week 96. The results suggested that higher increased ADAMTS13 and IL-12 after 48-week m-ETV treatment contributed to an enhanced probability of HBeAg SC, although the mechanism is undetermined. Quantification of ADAMTS13 (IL-12) during m-ETV treatment may help to predict long-term HBeAg SC in CHB patients.

Optimized ex vivo stimulation identifies multi-functional HBV-specific T cells in a majority of chronic hepatitis B patients

High antigen burden during chronic hepatitis B (CHB) results in a low frequency HBV-specific T cell response with restricted functionality. However, this observation is based on limited data because low T cell frequencies have hindered effective ex vivo analysis. We adapted the ELISpot assay to overcome this obstacle to measure ex vivo T cell responses in CHB patients. We modified the key variables of cell number and the peptide pulsing method to improve ex vivo detection of HBV-specific T cells. We detected IFN-γ responses in 10/15 vaccinated controls and 20/30 CHB patients, averaging 195 and 84 SFUs/2 × 10⁶ PBMCs respectively. Multi-analyte FluoroSpots improved functional characterization of T cells. We detected IFN-γ responses in all tested vaccinated controls (n = 10) and CHB patients (n = 13). IL-2 responses were detectable in 9/10 controls and 10/13 patients. TNF-α displayed less sensitivity, detectable in only 7/10 controls and 7/13 patients. Antigen-specific analysis demonstrated that IFN-γ responses were dominated by polymerase and core, with weak responses to envelope and X. IL-2 responses were found in 3/5 patients and equally directed towards polymerase and core. While their ex vivo frequency is extremely low, a fraction of HBV-specific T cells are detectable and display multi-functionality ex vivo.

Molecular, Evolutionary, and Structural Analysis of the Terminal Protein Domain of Hepatitis B Virus Polymerase, a Potential Drug Target

Approximately 250 million people are living with chronic hepatitis B virus (HBV) infections, which claim nearly a million lives annually. The target of all current HBV drug therapies (except interferon) is the viral polymerase; specifically, the reverse transcriptase domain. Although no high-resolution structure exists for the HBV polymerase, several recent advances have helped to map its functions to specific domains. The terminal protein (TP) domain, unique to hepadnaviruses such as HBV, has been implicated in the binding and packaging of the viral RNA, as well as the initial priming of and downstream synthesis of viral DNA—all of which make the TP domain an attractive novel drug target. This review encompasses three types of analysis: sequence conservation analysis, secondary structure prediction, and the results from mutational studies. It is concluded that the TP domain of HBV polymerase is comprised of seven subdomains (three unstructured loops and four helical regions) and that all three loop subdomains and Helix 5 are the major determinants of HBV function within the TP domain. Further studies, such as modeling inhibitors of these critical TP subdomains, will advance the TP domain of HBV polymerase as a therapeutic drug target in the progression towards a cure.

Checkpoint Inhibitors and Therapeutic Vaccines for the Treatment of Chronic HBV Infection

Treatment of chronic hepatitis B virus (HBV) infection is highly effective in suppressing viral replication, but complete cure is rarely achieved. In recent years, substantial progress has been made in the development of immunotherapy to treat cancer. Applying these therapies to improve the management of chronic HBV infection is now being attempted, and has become an area of active research. Immunotherapy with vaccines and checkpoint inhibitors can boost T cell functions in vitro, and therefore may be used to reinvigorate the impaired HBV-specific T cell response. However, whether these approaches will suffice and restore antiviral T cell immunity to induce long-term HBV control remains an open question. Recent efforts have begun to describe the phenotype and function of HBV-specific T cells on the single epitope level. An improved understanding of differing T cell specificities and their contribution to HBV control will be instrumental for advancement of the field. In this review, we outline correlates of successful versus inadequate T cell responses to HBV, and discuss the rationale behind therapeutic vaccines and checkpoint inhibitors for the treatment of chronic HBV infection.

The modulation of HBsAg level by sI126T is affected by additional amino acid substitutions in the S region of HBV

The hepatitis B surface antigen (HBsAg) is a vital serum marker for hepatitis B virus (HBV) infection. Amino acid (AA) substitutions in small hepatitis B surface protein (SHBs) are known to affect HBsAg level. However, how the genetic backbones of SHBs sequences would affect the roles of a specific AA substitution on HBsAg level remains unclear. In this study, we found that sI126 had a very high substitution detection rate of 17.54% (40/228) in untreated chronic hepatitis B cohort with subgenotype C2 HBV infection. Among different substitution types at sI126, the sI126T (N = 28) was found to be associated with significantly lower serum HBsAg level. Clone sequencing revealed that sI126T-harboring SHBs sequences had varied genetic backbones with zero to nine additional AA substitutions. Thus, we constructed 24 HBsAg expression plasmids harboring sI126T without (plasmid 1, P1) or with (P2-P24) additional AA substitution(s) and studied them in the HepG2 cells. The HBsAg levels were determined by both ELISA and Western blot. In vitro experiments showed that P1 significantly reduced HBsAg level and its secretion (p < .05), however, P2-P24 showed various extracellular and intracellular HBsAg levels. No significant differences were detected among the HBsAg mRNA levels of nine representative mutant plasmids. Our findings suggest that the modulation of HBsAg level by sI126T is affected by additional AA substitution(s) in the S region of HBV. The effects of AA combination substitutions in SHBs sequences on HBsAg levels are worthwhile for more attentions in terms of HBV biology and its clinical application.

Characterization and Clinical Significance of Natural Variability in Hepatitis B Virus Reverse Transcriptase in Treatment-Naive Chinese Patients by Sanger Sequencing and Next-Generation Sequencing

Mutations in hepatitis B virus (HBV) reverse transcriptase (RT) are associated with nucleos(t)ide analogue (NA) resistance during long-term antiviral treatment. However, the characterization of mutations in HBV RT in untreated patients has not yet been well illustrated. The objective of this study was to investigate the characterization and clinical significance of natural variability in HBV RT in treatment-naive patients. HBV RT sequences were analyzed in 427 patients by Sanger sequencing and in 66 patients by next-generation sequencing. Primary or secondary NA resistance (NA^r) mutations were not found, except A181T in RT (rtA181T) by Sanger sequencing, but they were detected by next-generation sequencing. Mutations were found in 56 RT amino acid (aa) sites by Sanger sequencing, 36 of which had mutations that could lead to changes in B or T cell epitopes in the RT or S protein. The distribution of mutations was diverse in different sections within the RT region. Multiple mutations showed significant association with HBV DNA, HBsAg, HBeAg, age, and severity of liver fibrosis. Mutations at rt251, rt266, rt274, rt280, rt283, rt284, and rt286 were found most in the advanced liver disease (ALD) group by next-generation sequencing. The present study demonstrates that next-generation sequencing (NGS) was more suitable than Sanger sequencing to monitor NA^r mutations at a low rate in the treatment-naive patients, and that mutations in the RT region might be involved in the progression to ALD.

Electronic Health Informatics Data To Describe Clearance Dynamics of Hepatitis B Surface Antigen (HBsAg) and e Antigen (HBeAg) in Chronic Hepatitis B Virus Infection

Advances in the diagnosis, monitoring, and treatment of hepatitis B virus (HBV) infection are urgently required if we are to meet international targets for elimination by the year 2030. Here we demonstrate how routine clinical data can be harnessed through an unbiased electronic pipeline, showcasing the significant potential for amassing large clinical data sets that can help to inform advances in patient care and provide insights that may help to inform new cure strategies. Our cohort from a large UK hospital includes adults from diverse ethnic groups that have previously been underrepresented in the literature. By tracking two protein biomarkers that are used to monitor chronic HBV infection, we provide new insights into the timelines of HBV clearance, both on and off treatment. These results contribute to improvements in individualized clinical care and may provide important clues into the immune events that underpin disease control.

HBsAg and HBeAg have gained traction as biomarkers of control and clearance during chronic hepatitis B virus infection (CHB). Improved understanding of the clearance correlates of these proteins could help inform improvements in patient-stratified care and advance insights into the underlying mechanisms of disease control, thus underpinning new cure strategies. We collected electronic clinical data via an electronic pipeline supported by the National Institute for Health Research Health Informatics Collaborative (NIHR HIC), adopting an unbiased approach to the generation of a robust longitudinal data set for adults testing HBsAg positive from a large UK teaching hospital over a 6-year period (2011 to 2016 inclusive). Of 553 individuals with CHB, longitudinal data were available for 319, representing >107,000 weeks of clinical follow-up. Among these 319 individuals, 13 (4%) cleared HBsAg completely. Among these 13, the HBsAg clearance rate in individuals on nucleos(t)ide analogue (NA) therapy (n = 4 [31%]; median clearance time,150 weeks) was similar to that in individuals not on NA therapy (n = 9 [69%]; median clearance time, 157 weeks). Those who cleared HBsAg were significantly older and less likely to be on NA therapy than nonclearers (P = 0.003 and P = 0.001, respectively). Chinese ethnicity was associated with HBeAg positivity (P = 0.025). HBeAg clearance occurred in individuals both on NA therapy (n = 24; median time, 49 weeks) and off NA therapy (n = 19; median time, 52 weeks). Improved insights into the dynamics of these biomarkers can underpin better prognostication and patient-stratified care. Our systematized approach to data collection paves the way for scaling up efforts to harness clinical data to address research questions and support improvements in clinical care.

Toward Curative Immunomodulation Strategies for Chronic Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection remains a major cause of morbidity and mortality worldwide. HBV surface antigen loss is considered a functional cure and is an ideal goal for antiviral therapy. However, current treatment regimens, including nucleos(t)ide analogues or interferons monotherapy and combination therapy, rarely achieve this goal in chronic hepatitis B patients. Nucleos(t)ide analogues (NAs), as well as many direct antiviral drugs in ongoing development, are able to inhibit HBV replication and gene expression, but it is hard to achieve immune control and prevent recurrence after therapy cessation. Host immunity, especially HBV-specific T cell response, is proven to play a critical role in control or clearance of HBV infection. Considering HBV chronically infected patients display varying degrees of dysfunction regarding their immune system, novel approaches to enhancing antiviral immune responses are necessary in order to combine with current antiviral agents. In this Review, we focus on the role of innate and adaptive immune responses in HBV immunopathogenesis and discuss attractive strategies or drugs that aim to activate or rebuild antiviral immunity to achieve the goal of an HBV functional cure.

Diverse Effects of the NTCP p.Ser267Phe Variant on Disease Progression During Chronic HBV Infection and on HBV preS1 Variability

The sodium taurocholate co-transporting polypeptide (NTCP) acts as a cellular receptor for the hepatitis B virus (HBV) infection on host hepatocytes. We aim to investigate how the NTCP p.Ser267Phe variant affects HBV-related disease progression and analyze viral genomic variability under a host genetic background carrying the p.Ser267Phe variant. A total of 3187 chronic hepatitis B (CHB) patients were enrolled and genotyped for the p.Ser267Phe variant. The variant's association with disease progression was evaluated by logistic regression analysis. We also enrolled 83 treatment-naive CHB patients to analyze the variability of the HBV preS1 region. The frequency of the NTCP p.Ser267Phe variant was significantly lower in patients diagnosed with acute-on-chronic liver failure [OR (95% CI) = 0.33 (0.18-0.58), P = 1.34 × 10^-4], cirrhosis [OR (95% CI) = 0.47 (0.31-0.72), P = 4.04 × 10^-4], and hepatocellular carcinoma [OR (95% CI) = 0.54 (0.34-0.86), P = 9.83 × 10^-3] as compared with CHB controls under the additive model after adjustment. Furthermore, the percentage of amino acid mutations in HBV preS1 region was significantly higher in the NTCP p.Ser267Phe heterozygote group than in the NTCP wild type homozygote group (P < 0.05). We herein demonstrate that the NTCP p.Ser267Phe variant is a protective factor reducing CHB patient risk for liver failure, cirrhosis, and hepatocellular carcinoma. A host genetic background carrying NTCP p.Ser267Phe exerts selective pressure on the virus, leading to more variability.

Immunomodulatory properties of cimetidine: Its therapeutic potentials for treatment of immune-related diseases

Histamine exerts potent modulatory impacts on the cells of innate- [including neutrophils, monocytes, macrophages, dendritic cells (DCs), natural killer (NK) cells and NKT cells] and adaptive immunity (such as Th1-, Th2-, Th17-, regulatory T-, CD8⁺ cytotoxic T cells, and B cells) through binding to histamine receptor 2 (H2R). Cimetidine, as an H2R antagonist, reverses the histamine-mediated immunosuppression, as it has powerful stimulatory effects on the effector functions of neutrophils, monocytes, macrophages, DCs, NK cells, NKT cells, Th1-, Th2-, Th17-, and CD8⁺ cytotoxic T cells. However, cimetidine reduces the regulatory/suppressor T cell-mediated immunosuppression. Experimentally, cimetidine potentiate some immunologic activities in vitro and in vivo. The therapeutic potentials of cimetidine as an immunomodulatory agent were also investigated in a number of human diseases (such as cancers, viral warts, allergic disorders, burn, and bone resorption) and vaccination. This review aimed to provide a concise summary regarding the impacts of cimetidine on the immune system and highlight the cellular mechanisms of action and the immunomodulatory effects of this drug in various diseases to give novel insights regarding the therapeutic potentials of this drug for treatment of immune-related disorders. The review encourages more investigations to consider the immunomodulatory characteristic of cimetidine for managing of immune-related disorders.