The Multiple Functions of B Cells in Chronic HBV Infection

Variation in innate immune responses to porcine epidemic diarrhea virus infection in piglets at different ages

Porcine epidemic diarrhea virus (PEDV) poses a significant threat to pigs, with piglets under seven days old facing a mortality rate of up to 100%. This study aimed to explore the maturation of the immune system in piglets across different age groups and their corresponding immune responses to PEDV infection. Real-time quantitative PCR was employed to assess the relative mRNA expression of inflammation-related factors in infected pigs compared to non-infected counterparts at varying ages. Additionally, flow cytometry was utilized to analyze the relative counts of CD4+ and CD8+ T cells, as well as CD21+ B cells, in peripheral blood, spleen, mesenteric lymph nodes, and Peyer's patches of piglets at different developmental stages. Our findings revealed a notable increase in IFN-α and IFN-γ, a decrease in TNF-α, and elevated expression of IL-1β, IL-6, IL-10, and IL-17 following PEDV infection. Furthermore, the numbers of CD4+ and CD8+ T cells, along with CD21+ B cells, exhibited a gradual rise with the advancement of piglets' age. Overall, our study underscores the progressive enhancement of piglets' resistance to PEDV infection as their immune system matures over time.

B cells enhance EphA2 chimeric antigen receptor T cells cytotoxicity against glioblastoma via improving persistence

Chimeric antigen receptor (CAR) T cell therapy is a powerful adoptive immunotherapy against blood cancers, but the therapeutic effect was not efficient enough on solid tumors. B cells have been reported to play a critical role in regulating memory T differentiation and cytotoxic T development. However, as of yet the influence of such B cells on CAR T cells has not been discussed. In this study, using ephrin type-A receptor 2 (EphA2) specific CAR T cells, we cultured B cells successfully to stimulate CAR T cells in vitro, and investigated the cell differentiation and anti-tumor efficiency. We observed that EphA2-CAR T cells stimulated by B cells performed increased interferon γ (IFN γ) production and upregulated OX40 expression, as well as the enhanced anti-tumor activity and reduced PD-1 expression. The persistence of CAR T cells was enhanced after B cells stimulation for more than 7 days with the increased subset of central memory T cells (TCM). In addition, next generation sequencing was performed to explore the underlying mechanisms. The up-regulated genes clustered in, immune response activation, chemokine signaling pathway, calcium signaling pathway, cGMP-PKG signaling pathway and et al. which contributed to the upregulated anti-glioblastoma (GBM) activity of CAR T cells stimulated by B cell. Furthermore, MEF2C, CD40, SYK and TNFRSF13B were upregulated in CAR T cells after co-culturing with B cells. These genes functionally enriched in promoting lymphocytes proliferation and may contribute to the enhanced persistence of CAR T cells. In conclusion, these results indicated the critical role of B cells in prolonging CAR T cells longevity and enhancing anti-tumor activity, which paves the way for the therapeutic exploitation of EphA2-CAR T cells against GBM in the future.

Elimination of the hepatitis B virus: A goal, a challenge

The hepatitis B elimination is a goal proposed by the WHO to be achieved by 2030 through the adoption of synergistic measures for the prevention and chronic HBV infection treatment. Complete cure is characterized by the HBV elimination from the body and is the goal of the chronic hepatitis B treatment, which once achieved, will enable the hepatitis B elimination. This, today, has been a scientific challenge. The difficulty in achieving a complete cure is due to the indefinite maintenance of a covalently closed episomal circular DNA (cccDNA) reservoir and the maintenance and persistence of an insufficient and dysfunctional immune response in chronically infected patients. Among the measures adopted to eliminate hepatitis B, two have the potential to directly interfere with the virus cycle, but with limited effect on HBV control. These are conventional vaccines-blocking transmission and antiviral therapy-inhibiting replication. Vaccines, despite their effectiveness in protecting against horizontal transmission and preventing mother-to-child vertical transmission, have no effect on chronic infection or potential to eliminate the virus. Treatment with antivirals suppresses viral replication, but has no curative effect, as it has no action against cccDNA. Therapeutic vaccines comprise an additional approach in the chronic infection treatment, however, they have only a modest effect on the immune system, enhancing it temporarily. This manuscript aims to address (1) the cccDNA persistence in the hepatocyte nucleus and the immune response dysfunction in chronically infected individuals as two primary factors that have hampered the treatment and HBV elimination from the human body; (2) the limitations of antiviral therapy and therapeutic vaccines, as strategies to control hepatitis B; and (3) the possibly promising therapeutic approaches for the complete cure and elimination of hepatitis B.

Using exploratory pharmacokinetic and pharmacodynamic analyses to predict the probability of flu-like symptoms in healthy volunteers and patients with chronic hepatitis B treated with the toll-like receptor 7 agonist ruzotolimod

Ruzotolimod (Toll-like receptor 7 (TLR7) agonist, RG7854) is an oral, small molecule immuno-modulator activating the TLR 7 and is being evaluated in patients with CHB. As with other TLR7 agonists, the study drug-related adverse events of flu-like symptoms have been reported in some participants during phase I studies with ruzotolimod. An exploratory analysis of the relationship between pharmacokinetic (PK)/pharmacodynamic (PD) and flu-like symptoms was performed in participants from two phase I studies including both healthy volunteers and NUC-suppressed CHB patients who received either single or multiple ascending doses of orally administered ruzotolimod. Linear and logistic regression were used to explore potential relationships between dose, flu-like symptoms, PK, and PD. Generalized linear regression was performed to predict the probability of flu-like symptoms of all intensities at different RO7011785 (the active metabolite of the double prodrug ruzotolimod) PK exposure. This analysis showed that single or multiple doses of ruzotolimod at ⩾100 mg, the immune PD (IFN-α, neopterin, IP-10, and the transcriptional expression of ISG15, OAS-1, MX1, and TLR7) responses increase with the RO7011785 PK exposure, which increases linearly with the doses from 3 mg to 170 mg of ruzotolimod. The analysis also showed that the probability of flu-like symptoms occurrence increases with PD responses (IFN-α and IP-10). Dose reduction of ruzotolimod can be an effective way to reduce the magnitude of PD response, thus reducing the probability of study drug-related flu-like symptoms occurrence at all intensity in the participants who are highly sensitive to PD activation and intolerant to flu-like symptoms.

A Comprehensive Review of Hepatitis B Vaccine Nonresponse and Associated Risk Factors

Hepatitis B virus (HBV) infection remains a significant global health concern worldwide, contributing to high rates of mortality and morbidity, including chronic hepatitis B, cirrhosis, and hepatocellular carcinoma (HCC). Universal vaccination programs have significantly reduced the rate of HBV transmission; however, a subset of individuals fail to develop a protective immune response following vaccination and are termed nonresponders. A comprehensive search strategy using the PubMed, Google Scholar, and Web of Science databases was employed to search for relevant studies using keywords including "hepatitis B vaccine", "vaccine nonresponse", "immunogenicity", "immune response to the hepatitis B vaccine", and "associated risk factors". Factors influencing the vaccine's response include demographic factors, such as age and sex, with increased nonresponse rates being observed in older adults and males. Obesity, smoking, and alcohol consumption are lifestyle factors that decrease the vaccine response. Medical conditions, including diabetes, chronic kidney and liver diseases, HIV, celiac disease, and inflammatory bowel disease, affect the vaccine response. Major histocompatibility complex (MHC) haplotypes and genetic polymorphisms linked to immune regulation are genetic factors that further influence the vaccine's effectiveness. To reduce the global burden of hepatitis B infection, it is essential to understand these factors to improve vaccine effectiveness and develop individualized vaccination strategies.

Effects of porcine epidemic diarrhea virus infection on CD21+ B cells activation

Porcine epidemic diarrhea virus (PEDV) is a devastating pathogen of acute- gastrointestinal infectious diseases, which can cause vomiting, diarrhea, dehydration and high morbidity and mortality among neonatal piglets. Humoral immunity plays a vital role in the host anti-PEDV infection process, but the mechanism of PEDV-induced B-cell immune response remains unknown. In this study, the effects of PEDV infection on CD21+ B cell activation were systematically analyzed through animal experiments. Enzyme-linked immunosorbent assays (ELISA) revealed that low levels of serum-specific IgA, IgM, or IgG were detected in piglets after PEDV infection, respectively. Serum interleukin (IL)-6 levels increased significantly at 4 d after infection, and the levels of IL-4, B-cell activating factor (BAFF), interferon (IFN)-γ, transforming growth factor (TGF)-β and IL-10 decreased at 7 d after infection. Fluorescence-activated cell sorting (FACS) showed that expression levels of CD21, MHC Ⅱ, CD40, and CD38 on B cell surfaces were significantly higher. In contrast, the proportions of CD21+IgM+ B cells were decreased in peripheral blood mononuclear cells (PBMCs) from the infected piglets. No differences were found in the percentage of CD21+CD80+ and CD21+CD27+ B cells in PBMCs from the infected piglets. In addition, the number of CD21+B cells in PBMCs stimulated with PEDV in vitro was significantly lower. No significant change in the mRNA expression of BCR molecules was found while the expression levels of paired immunoglobulin-like receptor B (PIR-B), B cell adaptor molecule of 32 kDa (Bam32) and BAFF were decreased. In conclusion, our research demonstrates that virulent strains of PEDV profoundly impact B cell activation, leading to alterations in phenotypic expression and BCR signaling molecules. Furthermore, this dysregulation results in compromised specific antibody secretion and perturbed cytokine production, highlighting the intricate immunological dysfunctions induced by PEDV infection.

Comparison of B cells' immune response induced by PEDV virulent and attenuated strains

Porcine epidemic diarrhea virus (PEDV) is an acute, highly contagious enterovirus that infects pigs of all ages. The B cells are important for antigen presentation, antibody production, and cytokine secretion to resist infection. However, the role of B cells in PEDV infection remains unclear. In this study, the effects of PEDV virulent (QY2016) and attenuated strains (CV777) on B cells sorted from neonatal piglets, nursery piglets, and gilts were investigated. The results showed that PEDV-QY2016 and PEDV-CV777 could significantly increase the expression of CD54 and CD27 in B cells from neonatal piglets. The percentages of CD80, MHC II, and IgM expressed on neonatal piglet B cells infected with PEDV-QY2016 were significantly lower than those expressed on the B cells infected with PEDV-CV777. Both PEDV-QY2016 and PEDV-CV777 could stimulate IFN-α and GM-CSF secretions in neonatal piglet B cells; IL-1, IFN-α, and IL-4 secretion in nursery piglet B cells; and IL-1, TGF-β secretion, and GM-CSF in gilt B cells. Furthermore, both PEDV-QY2016 and PEDV-CV777 could induce the secretion of IgA, IgM, and IgG in nursery piglet B cells but could not induce the secretion of IgA, IgM, and IgG in neonatal piglet B cells. The secretion of IgA, IgM, and IgG was significantly higher by the PEDV-CV777 strains infected B cells than those by the PEDV-QY2016 strains infected gilt B cells. In conclusion, the surface molecule expression, cytokine secretion, and antibody production of B cells induced by PEDV are closely related to the ages of pigs and the virulence of the PEDV strain.

Clinical characteristics and immunogenicity after Omicron breakthrough infection in patients with chronic hepatitis B infection: A longitudinal observational study

The clinical and immunological features after breakthrough infection (BTI) during Omicron wave in patients with chronic hepatitis B virus infection (CHB) are still unclear. A total of 101 patients with CHB from our previous coronavirus disease 2019 (COVID-19) vaccination cohort (NCT05007665), were continued to be followed up at the Second Affiliated Hospital of Chongqing Medical University after BTI, while an additional 39 healthcare workers after BTI were recruited as healthy controls (HCs). Clinical data were collected using questionnaire survey and electronic medical record. Blood samples were used to determine the antibody responses, as well as B and T cell responses. After BTI, the clinical symptoms of COVID-19 were mild to moderate in patients with CHB, with a median duration of 5 days. Compared with HCs, patients with CHB were more susceptible to develop moderate COVID-19. The liver function was not significantly damaged, and HBV-DNA was not activated in patients with CHB after BTI. Patients with CHB could elicit robust antibody responses after BTI (NAbs 13.0-fold, BA.5 IgG: 24.2-fold, respectively), which was also significantly higher than that in every period after vaccination (all p < 0.001), and compared to that in HCs after BTI. The CD4+, cTfh, and CD8+ T cell responses were also augmented in patients with CHB after BTI, while exhibiting comparability to those observed in HCs. In patients with CHB after BTI, the immune imprint was observed in B cell responses, rather than in T cell responses. In conclusion, Omicron breakthrough infection induced mild to moderate COVID-19 symptoms in patients with CHB, without exacerbating the progress of liver diseases. Meanwhile, BTI demonstrated the ability to induce robust antibody and T cell responses in patients with CHB, which was comparable to those observed in HCs.

Participation of B cell in immunotherapy of cancer

Even though their effector roles extend beyond conventional humoral immunity, B and plasma cells may exhibit antitumor effects through antibody-dependent cell cytotoxicity (ADCC) and activation of the complement cascade. Depending on whether they are positioned in immature or mature compartments termed tertiary lymphoid structures (TLS), which include T cells, B cells are believed to play numerous functions in modulating the immune system's capacity to destroy cancer cells. These formations represent a process of lymphoid neogenesis that takes place in peripheral tissues in response to prolonged exposure to inflammatory signals. Activated in the germinal centres of tertiary lymphoid structures, B cells may directly present tumor-associated antigens to T cells, make antibodies that enhance antigen presentation to T cells, or kill tumour cells, resulting in a favourable therapeutic effect. Immune complexes may also enhance inflammation, angiogenesis, and immunosuppression via the activation of macrophages and complement, resulting in detrimental effects. The functional variety of B-cell subsets includes professional antigen-presenting cells, regulatory cells, memory populations, and plasma cells that produce antibodies. Importantly, antibodies may independently generate innate immune responses and the cancer immunity cycle. B cells and B-cell-mediated antibody responses constitute the largely underestimated second arm of the adaptive immune system and unquestionably need more consideration in cancer. This article reviews the known roles of B lymphocytes in the tumour microenvironment, their contribution to anticancer activity of immunotherapies, and their significance in overall survival of cancer patients. In addition to producing antibodies, B cells regulate the immune system and serve as effective antigen-presenting cells.

Safety, pharmacodynamics, and antiviral activity of selgantolimod in viremic patients with chronic hepatitis B virus infection

Background & Aims

Novel finite therapies for chronic hepatitis B (CHB) are needed, since lifelong treatment is usually required with current available oral antivirals. This phase II study (NCT03615066) evaluated the safety, pharmacodynamics, and antiviral activity of selgantolimod (a Toll-like receptor 8 agonist [TLR8]) with tenofovir alafenamide (TAF).

Methods

Viremic patients with CHB not receiving treatment were stratified by HBeAg status and randomized 2:2:1 to TAF 25 mg/day with selgantolimod 3 mg orally once weekly (QW), selgantolimod 1.5 mg QW, or placebo. Combination therapy continued until week (W)24, followed by TAF monotherapy until W48; patients then discontinued TAF and were followed until W96 (treatment-free follow-up [TFFU] period). The primary efficacy endpoint was the proportion with ≥1 log10 IU/ml HBsAg decline at W24.

Results

Sixty-seven patients received study drug; 27 were followed during TFFU. Nausea, headache, vomiting, fatigue, and dizziness were the most common adverse events. Most adverse events were grade 1. Alanine aminotransferase flares were not observed up to W48. Four patients experienced alanine aminotransferase and hepatitis flares during TFFU; all had HBV DNA increases. Selgantolimod increased serum cytokines and chemokines and redistributed several circulating immune cell subsets. No patients achieved the primary efficacy endpoint. Mean HBsAg changes were -0.12, -0.16, and -0.12 log10 IU/ml in the selgantolimod 3 mg, selgantolimod 1.5 mg, and placebo groups, respectively, at W48; HBV DNA declined in all groups by ≥2 log10 IU/ml as early as W2, with all groups rebounding to baseline during TFFU. No HBsAg or HBeAg loss or seroconversion was observed throughout TFFU.

Conclusions

Selgantolimod up to 3 mg was safe and well tolerated. Pharmacodynamics and antiviral activity in viremic patients support continued study of selgantolimod in combination CHB therapies.

Impact and implications

Novel therapeutics for chronic HBV infection are needed to achieve a functional cure. In this study, we confirmed the safety and tolerability of selgantolimod (formerly GS-9688, a TLR8) when administered with tenofovir alafenamide over 24 weeks in viremic patients with chronic HBV infection. Overall, declines in HBsAg levels with selgantolimod treatment were modest; subgroup analysis indicated that patients with alanine aminotransferase levels greater than the upper limit of normal had significantly greater declines compared to those with normal alanine aminotransferase levels (-0.20 vs. -0.03 log10 IU/ml; p <0.001). These findings suggest a potential differential response to selgantolimod based on patients' baseline HBV-specific immune response, which should be considered in future investigations characterizing the underlying mechanisms of selgantolimod treatment and in HBV cure studies using similar immunomodulatory pathways.

Clinical trial number

NCT03615066 be found at https://www.gileadclinicaltrials.com/transparency-policy/.

The novel mechanism facilitating chronic hepatitis B infection: immunometabolism and epigenetic modification reprogramming

Hepatitis B Virus (HBV) infections pose a global public health challenge. Despite extensive research on this disease, the intricate mechanisms underlying persistent HBV infection require further in-depth elucidation. Recent studies have revealed the pivotal roles of immunometabolism and epigenetic reprogramming in chronic HBV infection. Immunometabolism have identified as the process, which link cell metabolic status with innate immunity functions in response to HBV infection, ultimately contributing to the immune system's inability to resolve Chronic Hepatitis B (CHB). Within hepatocytes, HBV replication leads to a stable viral covalently closed circular DNA (cccDNA) minichromosome located in the nucleus, and epigenetic modifications in cccDNA enable persistence of infection. Additionally, the accumulation or depletion of metabolites not only directly affects the function and homeostasis of immune cells but also serves as a substrate for regulating epigenetic modifications, subsequently influencing the expression of antiviral immune genes and facilitating the occurrence of sustained HBV infection. The interaction between immunometabolism and epigenetic modifications has led to a new research field, known as metabolic epigenomics, which may form a mutually reinforcing relationship with CHB. Herein, we review the recent studies on immunometabolism and epigenetic reprogramming in CHB infection and discuss the potential mechanisms of persistent HBV infection. A deeper understanding of these mechanisms will offer novel insights and targets for intervention strategies against chronic HBV infection, thereby providing new hope for the treatment of related diseases.

AAV Immunotoxicity: Implications in Anti-HBV Gene Therapy

Hepatitis B virus (HBV) has afflicted humankind for decades and there is still no treatment that can clear the infection. The development of recombinant adeno-associated virus (rAAV)-based gene therapy for HBV infection has become important in recent years and research has made exciting leaps. Initial studies, mainly using mouse models, showed that rAAVs are non-toxic and induce minimal immune responses. However, several later studies demonstrated rAAV toxicity, which is inextricably associated with immunogenicity. This is a major setback for the progression of rAAV-based therapies toward clinical application. Research aimed at understanding the mechanisms behind rAAV immunity and toxicity has contributed significantly to the inception of approaches to overcoming these challenges. The target tissue, the features of the vector, and the vector dose are some of the determinants of AAV toxicity, with the latter being associated with the most severe adverse events. This review discusses our current understanding of rAAV immunogenicity, toxicity, and approaches to overcoming these hurdles. How this information and current knowledge about HBV biology and immunity can be harnessed in the efforts to design safe and effective anti-HBV rAAVs is discussed.

Sustained Liver HBsAg Loss and Clonal T- and B-Cell Expansion upon Therapeutic DNA Vaccination Require Low HBsAg Levels

BACKGROUND

Suppression of HBV DNA, inhibition of HBV surface (HBsAg) production and therapeutic vaccination to reverse HBV-specific T-cell exhaustion in chronic HBV patients are likely required to achieve a functional cure. In the AAV-HBV mouse model, therapeutic vaccination can be effective in clearing HBV when HBsAg levels are low. Using a single-cell approach, we investigated the liver immune environment with different levels of HBsAg and sustained HBsAg loss through treatment with a GalNAc-HBV-siRNA followed by therapeutic vaccination.

METHODS

AAV-HBV-transduced C57BL/6 mice were treated with GalNAc-HBV-siRNA to lower HBsAg levels and then vaccinated using a DNA vaccine. We used single-cell RNA and V(D)J sequencing to understand liver immune microenvironment changes.

RESULTS

GalNAc-HBV-siRNA, followed by therapeutic vaccination, achieved sustained HBsAg loss in all mice. This was accompanied by CD4 follicular helper T-cell induction, polyclonal activation of CD8 T cells and clonal expansion of plasma cells that were responsible for antibody production.

CONCLUSIONS

This study provides novel insights into liver immune changes at the single-cell level, highlighting the correlation between induced reduction of HBsAg levels and clonal expansion of CD4, CD8 T cells and plasma cells in the liver upon HBV siRNA and subsequent therapeutic vaccination.

Immune response and treatment targets of chronic hepatitis B virus infection: innate and adaptive immunity

Chronic hepatitis B virus (HBV) infection is a major global public health risk that threatens human life and health, although the number of vaccinated people has increased. The clinical outcome of HBV infection depends on the complex interplay between viral replication and the host immune response. Innate immunity plays an important role in the early stages of the disease but retains no long-term immune memory. However, HBV evades detection by the host innate immune system through stealth. Therefore, adaptive immunity involving T and B cells is crucial for controlling and clearing HBV infections that lead to liver inflammation and damage. The persistence of HBV leads to immune tolerance owing to immune cell dysfunction, T cell exhaustion, and an increase in suppressor cells and cytokines. Although significant progress has been made in HBV treatment in recent years, the balance between immune tolerance, immune activation, inflammation, and fibrosis in chronic hepatitis B remains unknown, making a functional cure difficult to achieve. Therefore, this review focuses on the important cells involved in the innate and adaptive immunity of chronic hepatitis B that target the host immune system and identifies treatment strategies.

A Meta-Analysis of the Association Between Genetic Polymorphisms in IL-12, IL-17, and IL-21 and Risk of Hepatitis B Virus Infection

Cytokine imbalance is an important feature in the occurrence and outcome of hepatitis B virus (HBV). Single nucleotide polymorphisms (SNPs) within cytokine genes may affect the protein expression and eventually contribute to the susceptibility of HBV infection. The association between interleukin (IL)-12, IL-17, or IL-21 and the risk of HBV infection has been extensively studied, but yielding equivocal results. The aim of this meta-analysis was to determine the impact of SNPs in IL-12, IL-17, and IL-21 on the risk of HBV infection. We retrieved studies evaluating whether SNPs in IL-12, IL-17, and IL-21 influenced HBV infection from electronic databases, including PUBMED, Web of Science, EBOCO, OVID, and Embase. Summarized odds ratios (ORs) and confidence intervals (CIs) were calculated using STATA software. Under a homozygous comparison, the IL-12A rs568408 was associated with an increased risk of HBV infection in both overall analysis (OR = 1.68, 95% CI, 1.12-2.53) and Caucasians (OR = 1.80, 95% CI, 1.14-2.84). Under a dominant genetic model, the similarly higher risk was also observed in overall analysis (OR = 3.62, 95% CI, 3.08-4.24), Caucasians (OR = 3.29, 95% CI, 2.67-4.05), high-quality studies (OR = 3.29, 95% CI, 2.61-4.14), and low-quality studies (OR = 3.95, 95% CI, 3.17-4.93). Although no significant association was observed between IL-17A rs2275913 and the risk of HBV infection in overall comparison, subgroup analysis revealed that the IL-17A rs2275913 AA genotype was associated with a reduced risk in Asians (OR = 0.72, 95% CI, 0.57-0.91) and high-quality studies (OR = 0.71, 95% CI, 0.55-0.92). However, no significant association of IL12B rs3212227, IL-17A rs2275913, IL-21 rs2221903, and rs907715 with HBV infection was observed. In conclusion, we provide evidence that IL-12A rs568408 was associated with an increased risk of HBV infection and IL-17A rs2275913 AA genotype was a protective factor against HBV infection in Asians.

The Multiple Facets and Disorders of B Cell Functions in Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection continues to be a global public health burden. B cells play a pivotal role in mediating HBV clearance and can participate in the development of anti-HBV adaptive immune responses through multiple mechanisms, such as antibody production, antigen presentation, and immune regulation. However, B cell phenotypic and functional disorders are frequently observed during chronic HBV infection, suggesting the necessity of targeting the disordered anti-HBV B cell responses to design and test new immune therapeutic strategies for the treatment of chronic HBV infection. In this review, we provide a comprehensive summary of the multiple roles of B cells in mediating HBV clearance and pathogenesis as well as the latest developments in understanding the immune dysfunction of B cells in chronic HBV infection. Additionally, we discuss novel immune therapeutic strategies that aim to enhance anti-HBV B cell responses for curing chronic HBV infection.

Prospects for NK-based immunotherapy of chronic HBV infection

Effective and long-term treatment is required for controlling chronic Hepatitis B Virus (HBV) infection. Natural killer (NK) cells are antiviral innate lymphocytes and represent an essential arm of current immunotherapy. In chronic HBV (CHB), NK cells display altered changes in phenotypes and functions, but preserve antiviral activity, especially for cytolytic activity. On the other hand, NK cells might also cause liver injury in the disease. NK -based immunotherapy, including adoptive NK cell therapy and NK -based checkpoint inhibition, could potentially exploit the antiviral aspect of NK cells for controlling CHB infection while preventing liver tissue damage. Here, we review recent progress in NK cell biology under the context of CHB infection, and discuss potential NK -based immunotherapy strategies for the disease.

Enhanced Delivery of TLR7/8 Agonists by Metal-Organic Frameworks for Hepatitis B Virus Cure

Hepatitis B virus (HBV) infection remains a major challenge to global health due to unsatisfactory treatment efficacy, side effects of current therapies, and immune tolerance. Toll-like receptors 7/8 (TLR7/8) agonists have shown great potential in chronic hepatitis B (CHB) cure, but systemic administration often induces severe side effects due to rapid dispersion into the microvasculature. Herein, we encapsulate an imidazoquinoline-based TLR7/8 agonist (IMDQ) into zeolitic imidazolate framework 8 nanoparticles (IMDQ@ZIF-8 NPs) for HBV immunotherapy. Compared with free IMDQ, IMDQ@ZIF-8 NPs efficiently accumulate in the liver and are selectively taken up by antigen-presenting cells (APCs), leading to enhanced APC activation and efficient viral elimination in HBV-infected models. Strikingly, MDQ@ZIF-8 NP treatment results in the obvious production of anti-HBs antibody and seroconversion in HBV-infected mice. Overall, this study on the convergence of a facile assembly approach and efficient therapeutic effects represents a promising strategy for HBV treatment.

Interferon α facilitates anti-HBV cellular immune response in a B cell-dependent manner

OBJECTIVES

Dissecting the underlying mechanism of T cells remodeling mediated by interferon α (IFN-α) is indispensable for achieving an optimum therapeutic response in chronic hepatitis B (CHB) patients. However, little is known about B cells in this process. This study aims to elucidate the roles of B cells in IFN-α-mediated anti-hepatitis B virus (HBV) cellular immunity.

METHOD

The effects of B cells on IFN-α-mediated T cell response were investigated in B cell-deficient mouse model with HBV and IFN-α plasmid hydrodynamic injection. Single-cell RNA sequencing was performed to dissect the crosstalk among B cell and T cell subsets and the underlying molecule and pathway signatures on longitudinal blood samples from IFN-α-treated CHB patients.

RESULTS

B cell depletion impaired the functional T cell subsets, including HBV-specific CD8⁺ T cells, and engendered a delayed HBV clearance. IFN-α treatment boosted the response of HBV-specific CD8⁺ T cells, whereas such effects disappeared in B cell-deficient mice. The underlying mechanisms were associated with IFN-α-reinforced connections of B cells toward T cells as mediated by the antigen presentation and costimulatory functions in B cells.

CONCLUSION

IFN-α orchestrates protective HBV-specific cellular immunity in a B cell-dependent manner.

Hepatitis B and circadian rhythm of the liver

The circadian rhythm in humans is determined by the central clock located in the hypothalamus’s suprachiasmatic nucleus, and it synchronizes the peripheral clocks in other tissues. Circadian clock genes and clock-controlled genes exist in almost all cell types. They have an essential role in many physiological processes, including lipid metabolism in the liver, regulation of the immune system, and the severity of infections. In addition, circadian rhythm genes can stimulate the immune response of host cells to virus infection. Hepatitis B virus (HBV) infection is the leading cause of liver disease and liver cancer globally. HBV infection depends on the host cell, and hepatocyte circadian rhythm genes are associated with HBV replication, survival, and spread. The core circadian rhythm proteins, REV-ERB and brain and muscle ARNTL-like protein 1, have a crucial role in HBV replication in hepatocytes. In addition to influencing the virus’s life cycle, the circadian rhythm also affects the pharmacokinetics and efficacy of antiviral vaccines. Therefore, it is vital to apply antiviral therapy at the appropriate time of day to reduce toxicity and improve the effectiveness of antiviral treatment. For these reasons, understanding the role of the circadian rhythm in the regulation of HBV infection and host responses to the virus provides us with a new perspective of the interplay of the circadian rhythm and anti-HBV therapy. Therefore, this review emphasizes the importance of the circadian rhythm in HBV infection and the optimization of antiviral treatment based on the circadian rhythm-dependent immune response.

Innate and Adaptive Immunopathogeneses in Viral Hepatitis; Crucial Determinants of Hepatocellular Carcinoma

Viral hepatitis B (HBV) and hepatitis C (HCV) infections remain the most common risk factors for the development of hepatocellular carcinoma (HCC), and their heterogeneous distribution influences the global prevalence of this common type of liver cancer. Typical hepatitis infection elicits various immune responses within the liver microenvironment, and viral persistence induces chronic liver inflammation and carcinogenesis. HBV is directly mutagenic but can also cause low-grade liver inflammation characterized by episodes of intermittent high-grade liver inflammation, liver fibrosis, and cirrhosis, which can progress to decompensated liver disease and HCC. Equally, the absence of key innate and adaptive immune responses in chronic HCV infection dampens viral eradication and induces an exhausted and immunosuppressive liver niche that favors HCC development and progression. The objectives of this review are to (i) discuss the epidemiological pattern of HBV and HCV infections, (ii) understand the host immune response to acute and chronic viral hepatitis, and (iii) explore the link between this diseased immune environment and the development and progression of HCC in preclinical models and HCC patients.

Hepatitis B Flare in Hepatitis B e Antigen-Negative Patients: A Complicated Cascade of Innate and Adaptive Immune Responses

Chronic hepatitis B virus (HBV) infection is a dynamic process involving interactions among HBV, hepatocytes, and the host immune system. The natural course of chronic hepatitis B (CHB) is divided into four chronological phases, including the hepatitis B e antigen (HBeAg)-positive and HBeAg-negative phases. During HBV flare, alanine aminotransferase (ALT) levels abruptly rise to >5× the upper limit of normal; this is thought to occur due to the immune response against an upsurge in serum HBV DNA and antigen levels. Hepatitis flares may occur spontaneously, during or after antiviral therapy, or upon immunosuppression or chemotherapy in both HBeAg-positive and HBeAg-negative patients. The clinical spectrum of HBV flares varies from asymptomatic to hepatic decompensation or failure. HBeAg seroconversion with ≥ 1 year of consolidation therapy is accepted as an endpoint of oral antiviral therapy in HBeAg-positive patients, but recommendations for treating HBeAg-negative patients differ. Thus, the management of HBeAg-negative patients has attracted increasing interest. In the current review, we summarize various types of HBV flares and the associated complex cascade of innate and adaptive immune responses, with a focus on HBeAg-negative CHB patients. Hopefully, this review will provide insight into immunopathogenesis to improve the management of HBV flares in HBeAg-negative CHB patients.

Crosstalk between hepatic stellate cells and surrounding cells in hepatic fibrosis

Hepatic fibrosis represents as a dynamic pathological process characterized by the net accumulation of extracellular matrix in the progression of various chronic liver diseases, including viral hepatitis, alcoholic liver disease, and metabolic associated fatty liver disease (MAFLD). Activation of hepatic stellate cells (HSCs) is well-defined to play a central role in the initiation and progression of hepatic fibrosis. However, the activation of HSCs is affected by the complicated microenvironments in liver, which largely attributes to the communication between hepatocytes and multiple tissue-resident cells, including sinusoidal endothelial cells, bile duct epithelial cells, platelets, T cells, B cells, macrophages, natural killer cells, neutrophils, dendritic cells, in the direct or indirect mechanisms. Cellular crosstalk between HSCs and surrounding cells contributes to the activation of HSCs and the progression of hepatic fibrosis. Currently, accumulating evidence have proven the complexity and plasticity of HSCs activation, and further clarification of cellular communication between HSCs and surrounding cells will provide sufficient clue to the development of novel diagnostic methods and therapeutic strategies for hepatic fibrosis.

Role of Immune Cells in Patients with Hepatitis B Virus-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) develops almost entirely in the presence of chronic inflammation. Chronic hepatitis B virus (HBV) infection with recurrent immune-mediated liver damage ultimately leads to cirrhosis and HCC. It is widely accepted that HBV infection induces the dysfunction of the innate and adaptive immune responses that engage various immune cells. Natural killer (NK) cells are associated with early antiviral and antitumor properties. On the other hand, inflammatory cells release various cytokines and chemokines that may promote HCC tumorigenesis. Moreover, immunosuppressive cells such as regulatory T cells (Treg) and myeloid-derived suppressive cells play a critical role in hepatocarcinogenesis. HBV-specific CD8+ T cells have been identified as pivotal players in antiviral responses, whilst extremely activated CD8+ T cells induce enormous inflammatory responses, and chronic inflammation can facilitate hepatocarcinogenesis. Controlling and maintaining the balance in the immune system is an important aspect in the management of HBV-related HCC. We conducted a review of the current knowledge on the immunopathogenesis of HBV-induced inflammation and the role of such immune activation in the tumorigenesis of HCC based on the recent studies on innate and adaptive immune cell dysfunction in HBV-related HCC.

Immunopathology of Chronic Hepatitis B Infection: Role of Innate and Adaptive Immune Response in Disease Progression

More than 250 million people are living with chronic hepatitis B despite the availability of highly effective vaccines and oral antivirals. Although innate and adaptive immune cells play crucial roles in controlling hepatitis B virus (HBV) infection, they are also accountable for inflammation and subsequently cause liver pathologies. During the initial phase of HBV infection, innate immunity is triggered leading to antiviral cytokines production, followed by activation and intrahepatic recruitment of the adaptive immune system resulting in successful virus elimination. In chronic HBV infection, significant alterations in both innate and adaptive immunity including expansion of regulatory cells, overexpression of co-inhibitory receptors, presence of abundant inflammatory mediators, and modifications in immune cell derived exosome release and function occurs, which overpower antiviral response leading to persistent viral infection and subsequent immune pathologies associated with disease progression towards fibrosis, cirrhosis, and hepatocellular carcinoma. In this review, we discuss the current knowledge of innate and adaptive immune cells transformations that are associated with immunopathogenesis and disease outcome in CHB patients.

Transaminase Elevations during Treatment of Chronic Hepatitis B Infection: Safety Considerations and Role in Achieving Functional Cure

While current therapies for chronic HBV infection work well to control viremia and stop the progression of liver disease, the preferred outcome of therapy is the restoration of immune control of HBV infection, allowing therapy to be removed while maintaining effective suppression of infection and reversal of liver damage. This “functional cure” of chronic HBV infection is characterized by the absence of detectable viremia (HBV DNA) and antigenemia (HBsAg) and normal liver function and is the goal of new therapies in development. Functional cure requires removal of the ability of infected cells in the liver to produce the hepatitis B surface antigen. The increased observation of transaminase elevations with new therapies makes understanding the safety and therapeutic impact of these flares an increasingly important issue. This review examines the factors driving the appearance of transaminase elevations during therapy of chronic HBV infection and the interplay of these factors in assessing the safety and beneficial nature of these flares.