The third signal cytokine IL-12 rescues the anti-viral function of exhausted HBV-specific CD8 T cells

Integrating IL-12 mRNA nanotechnology with SBRT eliminates T cell exhaustion in preclinical models of pancreatic cancer

Pronounced T cell exhaustion characterizes immunosuppressive tumors, with the tumor microenvironment (TME) employing multiple mechanisms to elicit this suppression. Traditional immunotherapies, such as immune checkpoint blockade, often fail due to their focus primarily on T cells. To overcome this, we utilized a proinflammatory cytokine, interleukin (IL)-12, that re-wires the immunosuppressive TME by inducing T cell effector function while also repolarizing immunosuppressive myeloid cells. Due to toxicities observed with systemic administration of this cytokine, we utilized lipid nanoparticles encapsulating mRNA encoding IL-12 for intratumoral injection. This strategy has been proven safe and tolerable in early clinical trials for solid malignancies. We report an unprecedented loss of exhausted T cells and the emergence of an activated phenotype in murine pancreatic ductal adenocarcinoma (PDAC) treated with stereotactic body radiation therapy (SBRT) and IL-12mRNA. Our mechanistic findings reveal that each treatment modality contributes to the T cell response differently, with SBRT expanding the T cell receptor repertoire and IL-12mRNA promoting robust T cell proliferation and effector status. This distinctive T cell signature mediated marked growth reductions and long-term survival in local and metastatic PDAC models. This is the first study of its kind combining SBRT with IL-12mRNA and provides a promising new approach for treating this aggressive malignancy.

Dysfunction and regulatory interplay of T and B cells in chronic hepatitis B: immunotherapy and emerging antiviral strategies

In the context of chronic hepatitis B virus (HBV) infection, the continuous replication of HBV within host hepatocytes is a characteristic feature. Rather than directly causing hepatocyte destruction, this replication leads to immune dysfunction and establishes a state of T-B immune tolerance. Successful clearance of the HBV virus is dependent on the close collaboration between humoral and cellular immunity. Humoral immunity, mediated by B-cell subpopulations, and cellular immunity, dominated by T-cell subpopulations show varying degrees of dysfunction during chronic hepatitis B (CHB). Notably, not all T- and B-cells produce positive immune responses. This review examine the most recent developments in the mutual regulation of T-B cells during chronic HBV infection. Our focus is on the prevailing immunotherapeutic strategies, such as T cell engineering, HBV-related vaccines, PD-1 inhibitors, and Toll-like receptor agonists. While nucleos(t)ide analogues (NUCs) and interferons have notable limitations, including inadequate viral suppression, drug resistance, and adverse reactions, several HBV entry inhibitors have shown promising clinical efficacy. To overcome the challenges posed by NUCs or monotherapy, the combination of immunotherapy and novel antiviral agents presents a promising avenue for future CHB treatment and potential cure.

Hepatic Flare Following Effective Antiretroviral Therapy Is Associated With HBsAg Seroclearance in HBV/HIV-1 Co-Infection

Little is known about the clinical significance of hepatic flare following effective antiretroviral therapy (ART) on HBsAg seroclearance and prognosis in HBV/HIV co-infection. This observational cohort study recruited HBV/HIV-1 co-infected patients from the China National Free Antiretroviral Treatment Program. We obtained longitudinal information on demographic characteristics, clinical indicators, and treatment outcomes. Hepatic flare was defined as an elevation of ALT of more than five times the upper limit of the normal range without an upsurge of HBV DNA or HBsAg at any time point between ART initiation and 12 months. Among the 1354 enrolled patients, 98.7% received two anti-HBV drugs containing ART and 95.1% achieved good viral control. Hepatic flare was observed in 88 (6.5%) patients and was more frequent in those with lower baseline immune function but subsequently enhanced immune reconstitution. Over a median follow-up of 4.7 years, we observed 99 HBsAg seroclearance, 9 hepatic events, 6 HIV-associated malignancy, 3 non-HIV-associated malignancy, and 3 all-cause mortality. The 3-, 5-, and 10-year cumulative incidence of HBsAg seroclearance was 6.4%, 8.9%, and 12.9%, respectively. Compared to patients without hepatic flare, patients with hepatic flare had significantly higher rates of HBsAg seroclearance (13.6% vs. 6.9%, p = 0.018) but had no recorded adverse outcome. Multivariate analysis with different models indicated that hepatic flare was independently associated with HBsAg seroclearance especially in patients with low immune function, normal ALT, and high levels of HBV DNA and HBsAg at baseline. In HBV/HIV-1 co-infection, hepatic flare following effective ART is associated with HBsAg seroclearance. HBV-specific T cells immune reconstitution may represent a potential mechanism which deserves further investigation.

Old concepts, new tricks: How peptide vaccines are reshaping cancer immunotherapy?

Over the past few decades, research on cancer immunotherapy has firmly established immune cells as key players in effective cancer treatment. Peptide vaccines directly targeting immune cells have demonstrated immense potential due to their specificity and applicability. However, developing peptide vaccines to generate tumor-reactive T cells remains challenging, primarily due to suboptimal immunogenicity and overcoming the immunosuppressive tumor microenvironment (TME). In this review, we discuss various elements of effective peptide vaccines, including antigen selection, peptide epitope optimization, vaccine adjuvants, and the combination of multiple immunotherapies, in addition to recent advances in tumor neoantigens as well as epitopes bound by non-classical human leukocyte antigen (HLA) molecules, to increase the understanding of cancer peptide vaccines and provide multiple references for the design of subsequent T cell-based peptide vaccines.

HBV Biomarkers and Their Role in Guiding Treatment Decisions

Over 300 million individuals worldwide are chronically infected with hepatitis B virus and at risk for progressive liver disease. Due to the lack of a therapy that reliably achieves viral elimination and the variability of liver disease progression, treatment decisions are guided by the degree of liver disease and viral biomarkers as the viral life-cycle is well characterized and largely conserved between individuals. In contrast, the immunological landscape is much more heterogeneous and diverse and the measurement of its components is less well standardized. Due to the lack of a universal and easily measurable set of biomarkers, clinical practice guidelines remain controversial, aiming for a balance between simplifying treatment decisions by reducing biomarker requirements and using all available biomarkers to avoid overtreatment of patients with low risk for disease progression. While approved therapies such as nucleos(t)ide analogs improve patient outcomes, the inability to achieve a complete cure highlights the need for novel therapies. Since no treatment candidate has demonstrated universal efficacy, biomarkers will remain important for treatment stratification. Here, we summarize the current knowledge on virological and immunological biomarkers with a specific focus on how they might be beneficial in guiding treatment decisions in chronic hepatitis B.

Application of novel CAR technologies to improve treatment of autoimmune disease

Chimeric antigen receptor (CAR) T cell therapy has become an important treatment for hematological cancers, and its success has spurred research into CAR T cell therapies for other diseases, including solid tumor cancers and autoimmune diseases. Notably, the development of CAR-based treatments for autoimmune diseases has shown great progress recently. Clinical trials for anti-CD19 and anti-BCMA CAR T cells in treating severe B cell-mediated autoimmune diseases, like systemic lupus erythematosus (SLE), have shown lasting remission thus far. CAR T cells targeting autoreactive T cells are beginning clinical trials for treating T cell mediated autoimmune diseases. Chimeric autoantigen receptor (CAAR) T cells specifically target and eliminate only autoreactive B cells, and they have shown promise in treating mucosal pemphigus vulgaris and MuSK myasthenia gravis. Regulatory CAR T cells have also been developed, which show potential in altering autoimmune affected areas by creating a protective barrier as well as helping decrease inflammation. These new treatments are only the beginning of potential CAR T cell applications in treating autoimmune disease. Novel CAR technologies have been developed that increase the safety, potency, specificity, and efficacy of CAR T cell therapy. Applying these novel modifications to autoimmune CARs has the potential to enhance the efficacy and applicability of CAR therapies to autoimmune disease. This review will detail several recently developed CAR technologies and discuss how their application to autoimmune disease will improve this emerging field. These include logic-gated CARs, soluble protein-secreting CARs, and modular CARs that enable CAR T cell therapies to be more specific, reach a wider span of target cells, be safer for patients, and give a more potent cytotoxic response. Applying these novel CAR technologies to the treatment of autoimmune diseases has the potential to revolutionize this growing application of CAR T cell therapies.

Harnessing CD8+ T cell dynamics in hepatitis B virus-associated liver diseases: Insights, therapies and future directions

Hepatitis B virus (HBV) infection playsa significant role in the etiology and progression of liver-relatedpathologies, encompassing chronic hepatitis, fibrosis, cirrhosis, and eventual hepatocellularcarcinoma (HCC). Notably, HBV infection stands as the primary etiologicalfactor driving the development of HCC. Given the significant contribution ofHBV infection to liver diseases, a comprehensive understanding of immunedynamics in the liver microenvironment, spanning chronic HBV infection,fibrosis, cirrhosis, and HCC, is essential. In this review, we focused on thefunctional alterations of CD8+ T cells within the pathogenic livermicroenvironment from HBV infection to HCC. We thoroughly reviewed the roles ofhypoxia, acidic pH, metabolic reprogramming, amino acid deficiency, inhibitory checkpointmolecules, immunosuppressive cytokines, and the gut-liver communication in shapingthe dysfunction of CD8+ T cells in the liver microenvironment. Thesefactors significantly impact the clinical prognosis. Furthermore, we comprehensivelyreviewed CD8+ T cell-based therapy strategies for liver diseases,encompassing HBV infection, fibrosis, cirrhosis, and HCC. Strategies includeimmune checkpoint blockades, metabolic T-cell targeting therapy, therapeuticT-cell vaccination, and adoptive transfer of genetically engineered CD8+ T cells, along with the combined usage of programmed cell death protein-1/programmeddeath ligand-1 (PD-1/PD-L1) inhibitors with mitochondria-targeted antioxidants.Given that targeting CD8+ T cells at various stages of hepatitis Bvirus-induced hepatocellular carcinoma (HBV + HCC) shows promise, we reviewedthe ongoing need for research to elucidate the complex interplay between CD8+ T cells and the liver microenvironment in the progression of HBV infection toHCC. We also discussed personalized treatment regimens, combining therapeuticstrategies and harnessing gut microbiota modulation, which holds potential forenhanced clinical benefits. In conclusion, this review delves into the immunedynamics of CD8+ T cells, microenvironment changes, and therapeuticstrategies within the liver during chronic HBV infection, HCC progression, andrelated liver diseases.

PD-1 regulation in immune homeostasis and immunotherapy

Harnessing the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis is pivotal in autoimmunity and cancer immunotherapy. PD-1 receptors on immune cells engage with one of its ligands, PD-L1 or PD-L2, expressed on antigen-presenting cells or tumor cells, driving T-cell dysfunction and tumor immune escape. Thus, targeting PD-1/PD-L1 revitalizes cytotoxic T cells for cancer elimination. However, a majority of cancer patients don't respond to PD-1/PD-L1 blockade, and the underlying mechanisms remain partially understood. Recent studies have revealed that PD-1 expression levels or modifications impact the effectiveness of anti-PD-1/PD-L1 treatments. Therefore, understanding the molecular mechanisms governing PD-1 expression and modifications is crucial for innovating therapeutic strategies to enhance the efficacy of PD-1/PD-L1 inhibition. This article presents a comprehensive overview of advancements in PD-1 regulation and highlights their potential in modulating immune homeostasis and cancer immunotherapy, aiming to refine clinical outcomes.

Correlation Analysis of IL-17, IL-21, IL-23 with Non-Alcoholic Liver Fibrosis and Cirrhosis

Objective

This research aimed to explore the involvement of interleukins (IL) - IL-6, IL-17, IL-21, and IL-23 - in the evolution and diagnosis of non-alcoholic liver fibrosis and cirrhosis.

Methods

The study subjects were selected from the patients who visited the Department of Hepatology of X Hospital in Y City from August 2021 to April 2023. Peripheral blood samples were collected. All participants were divided into liver fibrosis, cirrhosis, hepatitis, and healthy subjects four groups. IL-21, IL-17, IL23, IL-6 were detected by double antibody sandwich.

Results

The results showed that there was a significant difference in the levels of IL-17, IL-21, and IL-23 among the 4 groups (P<0.0001). ROC curve analysis showed that the AUC values of IL-17, IL-21 and liver fiber 4 items were >0.70, suggesting that the diagnostic efficacy of IL-17, IL-21 was similar to that of liver fiber 4 items. Spearman correlation analysis showed that IL-17 had a positive correlation with collagen type III N-peptide, type IV collagen, and Laminin (P < 0.05), and no correlation with Hyaluronic acid (P > 0.05).

Conclusion

IL-17, IL-21, and IL-23 play a pivotal role in the inflammatory pathways associated with liver injuries, establishing themselves as potent auxiliary diagnostic markers in identifying liver fibrosis and cirrhosis.

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.

The Role of Interleukins in HBV Infection: A Narrative Review

Hepatitis B virus (HBV) infection is a worldwide medical issue with significant morbidity and mortality, as it is the main cause of chronic liver disease and hepatocellular carcinoma (HCC). Both innate and adaptive immune responses play a key role in HBV replication and suppression. Recently, the pathophysiological function of interleukins (IL) in the natural course of HBV has gained much attention as a result of the broad use of anti-interleukin agents for a variety of autoimmune diseases and the accompanying risk of HBV reactivation. We present a narrative review regarding the role of IL in HBV infection. Collectively, the pro-inflammatory ILs, namely IL-1, IL-5, IL-6, IL-12 and IL-21, seem to play a critical role in the suppression of HBV replication. In contrast, the anti-inflammatory cytokines IL-10, IL-23 and IL-35 probably act as HBV replication enhancers, while IL-17 has been correlated with HBV-related liver injury. Interestingly enough, IL-2, IL-4 and IL-12 have been tried as therapeutic options against HBV infection with contradictory results. Lastly, the role of IL-22 remains largely ill defined, although preliminary data suggest that it may play a significant role in HBV replication, proliferation and subsequent liver damage.

Local Delivery of SBRT and IL12 by mRNA Technology Overcomes Immunosuppressive Barriers to Eliminate Pancreatic Cancer

The immunosuppressive milieu in pancreatic cancer (PC) is a significant hurdle to treatments, resulting in survival statistics that have barely changed in 5 decades. Here we present a combination treatment consisting of stereotactic body radiation therapy (SBRT) and IL-12 mRNA lipid nanoparticles delivered directly to pancreatic murine tumors. This treatment was effective against primary and metastatic models, achieving cures in both settings. IL-12 protein concentrations were transient and localized primarily to the tumor. Depleting CD4 and CD8 T cells abrogated treatment efficacy, confirming they were essential to treatment response. Single cell RNA sequencing from SBRT/IL-12 mRNA treated tumors demonstrated not only a complete loss of T cell exhaustion, but also an abundance of highly proliferative and effector T cell subtypes. SBRT elicited T cell receptor clonal expansion, whereas IL-12 licensed these cells with effector function. This is the first report demonstrating the utility of SBRT and IL-12 mRNA in PC.

Statement of significance

This study demonstrates the use of a novel combination treatment consisting of radiation and immunotherapy in murine pancreatic tumors. This treatment could effectively treat local and metastatic disease, suggesting it may have the potential to treat a cancer that has not seen a meaningful increase in survival in 5 decades.

Impact of IL-12B Genetic Variants on Antiviral Treatment Response among Hepatitis B Patients in Pakistan

HBV is a continuous major global health concern. Genetic factors of hosts are known to play a role in HBV infection outcomes. This study aimed to reveal the association of IL-12b 3′ UTR variant rs3212227 in HBV patients. Genotyping was performed using ARMS-PCR to detect IL-12b rs3212227 polymorphism. The patients were categorized into groups based on their response to the antiviral therapy. Group I: non-sustained virological response (NSR); Group II: sustained virological responders (SVR); and Group III: HBV-positive fresh cases. ALT levels were measured to evaluate liver function, and viral load was determined to evaluate viral infectivity among the study groups. The variant genotype CC was found to be significantly associated with the non-sustained virological response to the antiviral therapy (with a p-value of 0.0117; OR = 2.914; RR = 1.556). It was also determined that the genotype CC was the most prevalent genotype among both genders in the NSR group. Viral load was found to be 6-fold higher in Group III compared to Group I and Group II. The results suggest that genotype CC is the most prevalent genotype in the NSR groups, and it is associated with a poor response to antiviral therapy in Pakistani patients with HBV infection.

Utility of novel viral and immune markers in predicting HBV treatment endpoints: A systematic review of treatment discontinuation studies

Background & Aims

Antivirals represent the mainstay of chronic hepatitis B treatment given their efficacy and tolerability, but rates of functional cure remain low during long-term therapy. Treatment discontinuation has emerged as a strategy to maintain partial cure and achieve functional cure in select patient groups. We aimed to evaluate how data from treatment discontinuation studies exploring novel viral and/or immune markers could be applied to the functional cure program.

Methods

Treatment discontinuation studies evaluating novel viral and/or immune markers were identified by a systematic search of the PubMed database through to October 30, 2022. Data extraction focused on information regarding novel markers, including identified cut-off levels, timing of measurement, and associated effect on study outcomes of virological relapse, clinical relapse, and HBsAg seroclearance.

Results

From a search of 4,492 citations, 33 studies comprising a minimum of 2,986 unique patients met the inclusion criteria. Novel viral markers, HBcrAg and HBV RNA, were demonstrated across most studies to be helpful in predicting off-therapy partial cure, with emerging evidence to support a link with functional cure. From novel immune marker studies, we observed that treatment discontinuation has the potential to trigger immune restoration, which may be associated with a transient virological relapse. To this end, these studies support the combination of virus-directing agents with immunomodulator therapies to induce two key steps underlying functional cure: viral antigen load reduction and restoration of the host immune response.

Conclusions

Patients with a favourable profile of novel viral and immune markers stand to benefit from a trial of antiviral treatment discontinuation alongside novel virus-directing agents with the aim of achieving functional cure without excessive risk of severe clinical relapse.

Impact and implications

Select patients with chronic hepatitis B undergoing nucleoside analogue therapy may benefit from a trial of treatment discontinuation, aiming to maintain partial cure and/or achieve functional cure. We propose a profile of novel viral and immune markers to identify patients who are likely to achieve these goals without excessive risk of hepatic decompensation. Furthermore, treatment discontinuation may also be considered as a therapeutic strategy to trigger immune restoration, which may increase the chance of functional cure when used in conjunction with novel virus-directing agents.

Antigen Recognition and Immune Response to Acute and Chronic Hepatitis B Virus Infection

The antigen recognition and immune response to acute and chronic hepatitis B virus (HBV) infections are the result of both the innate and adaptive immune response. The innate immune response comprises Dendritic Cells (DCs), which served as professional antigen-presenting cells and a bridge between innate and adaptive immunity, Kupffer cells and inflammatory monocytes for the continuous inflammation of hepatocyte, neutrophils for hepatic tissue damage due to acute inflammation, type I interferons (IFN), which induce an antiviral state on infected cells, directs natural killer (NK) cells to kill virally infected cells, reduces the population of infected cells, and promotes the effective maturation and site recruitment of adaptive immunity through the production of pro-inflammatory cytokines and chemokines. Through stimulating B cells, T-helper, and cytotoxic T cells, the adaptive immune system also protects against hepatitis B infection. During HBV infection, a network of cell types that can either play protective or harmful functions creates the anti-viral adaptive immune response. These many elements, such as ‎Cluster of differentiation four (CD4) T cells (traditionally known as helper T cells), are potent cytokine producers and necessary for the effective maturation of effector cytotoxic cluster of differentiation eight (CD8) T cells and B cell antibody production. By cytolytic and non-cytolytic processes, CD8 T cells are able to eliminate HBV-infected hepatocytes and directly detect virus-infected cells, and circulating CD4+ CD25+ regulatory T cells for the modulation of immune system. In order to avoid reinfection, B cells can produce antibodies that destroy free viral particles. Moreover, by presenting HBV antigens to helper T cells, B cells may also influence how well these cells operate.

Individual Epitope-Specific CD8+ T Cell Immune Responses Are Shaped Differently during Chronic Viral Infection

A hallmark in chronic viral infections are exhausted antigen-specific CD8⁺ T cell responses and the inability of the immune system to eliminate the virus. Currently, there is limited information on the variability of epitope-specific T cell exhaustion within one immune response and the relevance to the T cell receptor (TCR) repertoire. The aim of this study was a comprehensive analysis and comparison of three lymphocytic choriomeningitis virus (LCMV) epitope-specific CD8⁺ T cell responses (NP396, GP33 and NP205) in a chronic setting with immune intervention, e.g., immune checkpoint inhibitor (ICI) therapy, in regard to the TCR repertoire. These responses, though measured within the same mice, were individual and independent from each other. The massively exhausted NP396-specific CD8⁺ T cells revealed a significantly reduced TCR repertoire diversity, whereas less-exhausted GP33-specific CD8⁺ T cell responses were rather unaffected by chronicity in regard to their TCR repertoire diversity. NP205-specific CD8⁺ T cell responses showed a very special TCR repertoire with a prominent public motif of TCR clonotypes that was present in all NP205-specific responses, which separated this from NP396- and GP33-specific responses. Additionally, we showed that TCR repertoire shifts induced by ICI therapy are heterogeneous on the epitope level, by revealing profound effects in NP396-, less severe and opposed effects in NP205-, and minor effects in GP33-specific responses. Overall, our data revealed individual epitope-specific responses within one viral response that are differently affected by exhaustion and ICI therapy. These individual shapings of epitope-specific T cell responses and their TCR repertoires in an LCMV mouse model indicates important implications for focusing on epitope-specific responses in future evaluations for therapeutic approaches, e.g., for chronic hepatitis virus infections in humans.

Developments in pharmacotherapeutic agents for hepatitis B - how close are we to a functional cure?

INTRODUCTION

Hepatitis B virus (HBV) remains a public health concern given its global prevalence and potential complications including hepatocellular carcinoma (HCC). Current therapies, including nucleos(t)ide analogs (NA) and interferons (IFN), are effective in chronic treatment of HBV but rarely provide a functional cure due to inadequate host response and the presence of viral DNA. Therefore, novel therapies that enhance the innate immune response while suppressing DNA transcription may provide definitive treatment of HBV.

AREAS COVERED

In this review, the authors provide a brief overview of commonly used agents and their efficacy in treatment of HBV. Newer therapies with direct antiviral agents such as bepirovirsen (antisense oligonucleotide (ASO)) and entry inhibitors such as bulevirtide have shown efficacy in reducing viral load but demonstrate further reductions in conjunction with immune modulators such as therapeutic vaccines.

EXPERT OPINION

Combination therapy is far superior to monotherapy alone, necessitating the need for both immunomodulators and direct antiviral agents in chronic treatment of HBV. Therapies that target covalently closed circular (cccDNA) with immunomodulators like therapeutic vaccines have shown promising results and may ultimately achieve functional cure. However, therapies need to be evaluated in the context of the patient, considering both financial and socioeconomic factors.

A nanoadjuvant that dynamically coordinates innate immune stimuli activation enhances cancer immunotherapy and reduces immune cell exhaustion

Although conventional innate immune stimuli contribute to immune activation, they induce exhausted immune cells, resulting in suboptimal cancer immunotherapy. Here we suggest a kinetically activating nanoadjuvant (K-nanoadjuvant) that can dynamically integrate two waves of innate immune stimuli, resulting in effective antitumour immunity without immune cell exhaustion. The combinatorial code of K-nanoadjuvant is optimized in terms of the order, duration and time window between spatiotemporally activating Toll-like receptor 7/8 agonist and other Toll-like receptor agonists. K-nanoadjuvant induces effector/non-exhausted dendritic cells that programme the magnitude and persistence of interleukin-12 secretion, generate effector/non-exhausted CD8⁺ T cells, and activate natural killer cells. Treatment with K-nanoadjuvant as a monotherapy or in combination therapy with anti-PD-L1 or liposomes (doxorubicin) results in strong antitumour immunity in murine models, with minimal systemic toxicity, providing a strategy for synchronous and dynamic tailoring of innate immunity for enhanced cancer immunotherapy.

Abnormally primed CD8 T cells: The Achilles' heel of CHB

Chronic hepatitis B virus (HBV) infection continues to be a significant public health challenge, and more than 250 million people around world are infected with HBV. The clearance of HBV with virus-specific CD8 T cells is critical for a functional cure. However, naïve HBV-specific CD8 T cells are heavily hindered during the priming process, and this phenomenon is closely related to abnormal cell and signal interactions in the complex immune microenvironment. Here, we briefly summarize the recent progress in understanding the abnormal priming of HBV-specific CD8 T cells and some corresponding immunotherapies to facilitate their functional recovery, which provides a novel perspective for the design and development of immunotherapy for chronic HBV infection (CHB). Finally, we also highlight the balance between viral clearance and pathological liver injury induced by CD8 T-cell activation that should be carefully considered during drug development.

Identification of antibodies cross-reactive with woodchuck immune cells and activation of virus-specific and global cytotoxic T cell responses by anti-PD-1 and anti-PD-L1 in experimental chronic hepatitis B and persistent occult hepadnaviral infection

Woodchuck (Marmota monax) infected with woodchuck hepatitis virus (WHV) is the most pathogenically compatible naturally occurring model of human hepatitis B virus (HBV) infection, chronic hepatitis B, and HBV-induced hepatocellular carcinoma. This system plays a crucial role in discovery and preclinical evaluation of anti-HBV therapies. Its utilization remains tempered by the relatively narrow range of validated immunologic and molecular tools. We evaluated commercial antibodies against immune cell phenotypic markers and T cell molecules for cross-reactivity with woodchuck antigenic equivalents. The confirmed antibodies against programed cell death protein-1 (PD-1) and its ligand (PD-L1) were examined for ex vivo ability to activate WHV-specific, global and bystander cytotoxic T cells (CTLs) in chronic hepatitis and asymptomatic infection persisting after self-resolved acute hepatitis. Examination of 65 antibodies led to identification or confirmation of 23 recognizing woodchuck T, regulatory T, B and natural killer cells, T cell-associated PD-1, PD-L1, CTLA-4 and TIM-3 molecules, CD25 and CD69 markers of T cell activation, and interferon gamma (IFNγ). Antibodies against woodchuck PD-1 and PD-L1 triggered in vitro highly individualized WHV-specific and global activation of CTLs in both chronic hepatitis and persistent occult infection. WHV-specific CTLs were more robustly augmented by anti-PD-1 than by anti-PD-L1 in chronic hepatitis, while global IFNγ-positive CTL response was significantly suppressed in chronic hepatitis compared to persistent occult infection. Anti-PD-1 and anti-PD-L1 also occasionally activated CTLs to specificities other than those tested suggesting their potency to trigger side effects. This was particularly apparent when T cells from chronic hepatitis were treated with anti-PD-L1. The current findings indicate that inhibition of the PD-1/PD-L1 pathway could reactivate virus-specific and global T cell responses in both chronic hepatitis and asymptomatic persistent infection. They suggest a mechanism of potential reactivation of clinically silent infection during anti-PD-1/PD-L1 treatment and indicate that this therapy may also subdue occult HBV infection.

CTLs: Killers of intracellular bacteria

Many microbial pathogens have evolved a range of capabilities to evade host immune defense mechanisms and to survive and multiply in host cells. The presence of host intracellular bacteria makes it difficult for specific antibodies to function. After the intracellular bacteria escape the attack of the innate immune system, such as phagocytes, they survive in cells, and then adaptive immunity comes into play. Cytotoxic T lymphocytes (CTLs) play an important role in eliminating intracellular bacteria. The regulation of key transcription factors could promote CD4+/CD8+ T cells to acquire cytolytic ability. The TCR-CD3 complex transduces activation signals generated by TCR recognition of antigen and promotes CTLs to generate multiple pathways to kill intracellular bacteria. In this review, the mechanism of CD4/CD8 CTLs differentiation and how CD4/CD8 CTLs kill intracellular bacteria are introduced. In addition, their application and prospects in the treatment of bacterial infections are discussed.

Targeting mitochondrial quality control of T cells: Regulating the immune response in HCC

Most of the primary hepatocellular carcinoma (HCC) develops from Viral Hepatitis including Hepatitis B virus, Hepatitis C Virus, and Nonalcoholic Steatohepatitis. Herein, T cells play crucial roles combined with chronic inflammation and chronic viral infection. However, T cells are gradually exhausted under chronic antigenic stimulation, which leads to T cell exhaustion in the tumor microenvironment, and the exhaustion is associated with mitochondrial dysfunction in T cells. Meanwhile, mitochondria play a crucial role in altering T cells’ metabolism modes to achieve desirable immunological responses, wherein mitochondria maintain quality control (MQC) and promote metabolism regulation in the microenvironment. Although immune checkpoint inhibitors have been widely used in clinical practice, there are some limitations in the therapeutic effect, thus combining immune checkpoint inhibitors with targeting mitochondrial biogenesis may enhance cellular metabolic adaptation and reverse the exhausted state. At present, several studies on mitochondrial quality control in HCC have been reported, however, there are gaps in the regulation of immune cell function by mitochondrial metabolism, particularly the modulating of T cell immune function. Hence, this review summarizes and discusses existing studies on the effects of MQC on T cell populations in liver diseases induced by HCC, it would be clued by mitochondrial quality control events.

Serum Interleukins as Potential Prognostic Biomarkers in HBV-Related Acute-on-Chronic Liver Failure

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is relatively common in China and has complex pathogenesis, difficult clinical treatment, and poor prognosis. Immune status is an important factor affecting ACLF prognosis. Interleukins are a family of secreted lymphocyte factors that interact with a host of cell types including immune cells. These signaling molecules play important roles in transmitting information; regulating immune cells; mediating the activation, proliferation, and differentiation of T and B cells; and modulating inflammatory responses. Many studies have investigated the correlation between interleukin expression and the prognosis of HBV-ACLF. This review focuses on the potential use of interleukins as prognostic biomarkers in HBV-ACLF. References were mainly identified through PubMed and CNKI search, including relevant studies published until December 2021. We have summarized reports of several promising diagnostic interleukin biomarkers that predict susceptibility to HBV-ACLF. The use of biomarkers to understand early prognosis can help devise different therapeutic measures and improve patient survival. Ongoing research on prognostic biomarkers of HBV-ACLF is promising, and future preclinical and clinical studies are warranted.

Future anti-HDV treatment strategies, including those aimed at HBV functional cure

HDV is a defective virus that uses the HBV surface antigen to enter hepatocytes. It is associated with an accelerated course of liver fibrosis progression and an increased risk of hepatocellular carcinoma. Negative HDV RNA 24 weeks after the end of therapy has been proposed as an endpoint but late relapses make this endpoint suboptimal, hence HBsAg loss appears to be more appropriate. Current HBV antiviral agents have poor activity against HDV hence the search for improved therapy. Drugs only active against HDV, such as lonafarnib, have shown efficacy in combination with nucleoside analogues and peginterferon, but do not lead to HBsAg loss. HBsAg loss sustained 24 weeks after the end of therapy with negative HBV DNA is termed functional cure. Agents that are being investigated for functional cure include those that inhibit replication such as entry inhibitors, polymerase inhibitors and capsid assembly modulators but seldom lead to functional cure. Agents that reduce HBV antigen load such as RNA interference and inhibitors of HBsAg secretion are promising. Immunomodulators on their own seldom achieve functional cure, hence these agents in combination to assess the optimal combination are being investigated. Consequently, agents leading to functional cure of HBV are ideal for both HBV and HDV.

Toll-like receptor-mediated innate immunity orchestrates adaptive immune responses in HBV infection

Chronic hepatitis B virus (HBV) infection remains to be a substantial global burden, especially for end-stage liver diseases. It is well accepted that HBV-specific T and B cells are essential for controlling HBV infection. Toll-like receptors (TLRs) represent one of the major first-line antiviral defenses through intracellular signaling pathways that induce antiviral inflammatory cytokines and interferons, thereby shaping adaptive immunity. However, HBV has evolved strategies to counter TLR responses by suppressing the expression of TLRs and blocking the downstream signaling pathways, thus limiting HBV-specific adaptive immunity and facilitating viral persistence. Recent studies have stated that stimulation of the TLR signaling pathway by different TLR agonists strengthens host innate immune responses and results in suppression of HBV replication. In this review, we will discuss how TLR-mediated responses shape HBV-specific adaptive immunity as demonstrated in different experimental models. This information may provide important insight for HBV functional cure based on TLR agonists as immunomodulators.

Getting to HBV cure: The promising paths forward

Chronic HBV infection is a global public health burden estimated to impact nearly 300 million persons worldwide. Despite the advent of potent antiviral agents that effectively suppress viral replication, HBV cure remains difficult to achieve because of the persistence of covalently closed circular DNA (cccDNA), HBV-DNA integration into the host genome, and impaired immune response. Indefinite treatment is necessary for most patients to maintain level of viral suppression. The success of direct-acting antivirals (DAAs) for hepatitis C treatment has rejuvenated the search for a cure for chronic hepatitis B (CHB), though an HBV cure likely requires an additional layer: immunomodulators for restoration of robust immune responses. DAAs such as entry inhibitors, capsid assembly modulators, inhibitors of subviral particle release, cccDNA silencers, and RNA interference molecules have reached clinical development. Immunomodulators, namely innate immunomodulators (Toll-like receptor agonists), therapeutic vaccines, checkpoint inhibitors, and monoclonal antibodies, are also progressing toward clinical development. The future of the HBV cure possibly lies in triple combination therapies with concerted action on replication inhibition, antigen reduction, and immune stimulation. Many obstacles remain, such as overcoming translational failures, choosing the right endpoint using the right biomarkers, and leveraging current treatments in combination regimens to enhance response rates. This review gives an overview of the current therapies for CHB, HBV biomarkers used to evaluate treatment response, and development of DAAs and immune-targeting drugs and discusses the limitations and unanswered questions on the journey to an HBV cure.

Immunomodulation and RNA interference alter hepatitis B virus-specific CD8 T-cell recognition of infected HepG2-NTCP

BACKGROUND AND AIMS

CD8 T cells are essential in controlling HBV infection. Viral control is dependent on efficient recognition of HBV-infected hepatocytes by CD8 T cells, which can induce direct lysis of infected hepatocytes. In addition, CD8 T cells produce interferon (IFN)-γ, which mediates noncytopathic viral clearance. Innate immunomodulators and HBV-targeted RNA interference (RNAi) are being developed to treat chronic hepatitis B (CHB), but may modify HBV antigen presentation and impact CD8 T-cell recognition, in addition to their primary mechanisms of action.

APPROACH AND RESULTS

HBV-infected HepG2-NTCP cells were treated with tenofovir disoproxil fumarate (TDF), Toll-like receptor (TLR) 7/8 agonists, TLR7/8 conditioned media (CM) collected from immune cells, or RNAi using short interfering RNAs. The effect of these treatments on antigen presentation was measured through coculture with CD8 T cells recognizing human leukocyte antigen-A0201 restricted epitopes, HBc18-27 or HBs183-191. Cytokine profiles of TLR7/8 CM were measured using a cytometric bead array. TDF reduced viral replication, but not CD8 T-cell recognition, of infected cells. Direct exposure of infected HepG2-NTCP to TLR7/8 agonists had no impact on T-cell recognition. Exposure of infected HepG2-NTCP to TLR7/8 CM enhanced HBV-specific CD8 T-cell recognition through type 1 interferon (IFN) and IFN-γ-dependent mechanisms. RNAi rapidly suppressed HBV-DNA, HBcAg, and HBsAg expression, impairing recognition by HBV-specific CD8 T cells.

CONCLUSIONS

Immunomodulation and RNAi, but not nucleos(t)ide analogues, alter the recognition of infected HepG2-NTCP by HBV-specific CD8 T cells. Understanding these changes will inform combination treatments for CHB.

Significance of T-Cell Subsets for Clinical Response to Peginterferon Alfa-2a Therapy in HBeAg-Positive Chronic Hepatitis B Patients

Introduction

The adaptive immune response may reflect the immunomodulatory efficacy during peginterferon alfa-2a (PEG-IFN α-2a) treatment in chronic hepatitis B (CHB) patients. We evaluated the predictive efficiency of T-cell subsets on patient's response to PEG-IFN α-2a treatment.

Methods

The proportions of CD8+PD-1+, CD8+Tim-3+ and CD4+CD25high T-cells were measured at baseline and week 52 in CHB patients who underwent PEG-IFN α-2a treatment. The proportions of T-cell subsets were compared among different responders and non-responders (determined by biochemical, serological, and virological responses).

Results

The baseline proportions of the three T-cell subsets were significantly higher in CHB patients (65 cases) than in healthy controls (28 cases), while the proportions declined significantly after 52 weeks of PEG-IFN treatment. Responders (ALT < 40 IU/L, 89.2% [58/65]; HBV DNA < 2.7 log10 IU/ml, 66.2% [43/65]; and HBeAg seroconversion [SR], 53.9% [35/65]) experienced more pronounced declines in the proportion of T-cell subsets compared to non-responders. In particular, the baseline proportions of CD4+CD25high T-cells displayed significant difference between SR and non-SR groups. The stepwise logistic regression analysis identified that CD4+CD25high T-cells combined with baseline HBV DNA and ALT can predict SR and CR (ALT < 40 IU/L, HBV DNA < 2.7 log10 IU/mL and HBeAg seroconversion) after 52 weeks of PEG-IFN treatment with high accuracy.

Conclusion

PEG-IFN therapy induces significant declines in the proportion of some key T-cell subsets in HBeAg-positive patients. The model constructed with CD4+CD25high T-cells combined with ATL and HBV DNA may help to predict the efficacy of PEG-IFN α-2a therapy.

Risk of hepatitis B reactivation: From biologic therapies for psoriasis to immunosuppressive therapies for COVID‑19 (Review)

The cytokine storm from the evolution of severe cases of COVID-19, requiring strong immunosuppressive therapies, has raised the issue of reactivation of hepatitis B virus (HBV) infections in these patients. An analysis of the first observational studies in patients with COVID-19 and immunosuppressive therapy and HBV infection along with special clinical cases was presented, as well as personal experience on a series of cases (a group of 958 patients with COVID-19), compared with the analysis of studies performed on patients with HBV infection that underwent biological therapies for psoriasis and personal experience (a group of 81 psoriasis patients treated with biological therapies). Clinical studies have revealed that HBV reactivation in patients undergoing biological therapies for psoriasis, can be prevented with monitoring and treatment protocols and thus, these therapies have been demonstrated to be safe and effective. In COVID-19, immunosuppressive therapies are short-lived but in high doses, and the conclusions of clinical trials are contradictory, but there are published cases of HBV reactivation, which requires a unitary attitude in the prevention of HBV reactivation in these patients. An algorithm was presented for monitoring and treatment of HBV infection for patients with psoriasis treated with biological therapy and the conditions when this protocol can be used for patients with COVID-19 and immunosuppressive therapy.

Innate and adaptive immune escape mechanisms of hepatitis B virus

Chronic hepatitis B virus (HBV) infection is an international health problem with extremely high mortality and morbidity rates. Although current clinical chronic hepatitis B (CHB) treatment strategies can partly inhibit and eliminate HBV, viral breakthrough may result due to non-adherence to treatment, the emergence of viral resistance, and a long treatment cycle. Persistent CHB infection arises as a consequence of complex interactions between the virus and the host innate and adaptive immune systems. Therefore, understanding the immune escape mechanisms involved in persistent HBV infection is important for designing novel CHB treatment strategies to clear HBV and achieve long-lasting immune control. This review details the immunological and biological characteristics and escape mechanisms of HBV and the novel immune-based therapies that are currently used for treating HBV.

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.

Knowns and Unknowns about CAR-T Cell Dysfunction

Immunotherapy using chimeric antigen receptor (CAR) T cells is a promising option for cancer treatment. However, T cells and CAR-T cells frequently become dysfunctional in cancer, where numerous evasion mechanisms impair antitumor immunity. Cancer frequently exploits intrinsic T cell dysfunction mechanisms that evolved for the purpose of defending against autoimmunity. T cell exhaustion is the most studied type of T cell dysfunction. It is characterized by impaired proliferation and cytokine secretion and is often misdefined solely by the expression of the inhibitory receptors. Another type of dysfunction is T cell senescence, which occurs when T cells permanently arrest their cell cycle and proliferation while retaining cytotoxic capability. The first section of this review provides a broad overview of T cell dysfunctional states, including exhaustion and senescence; the second section is focused on the impact of T cell dysfunction on the CAR-T therapeutic potential. Finally, we discuss the recent efforts to mitigate CAR-T cell exhaustion, with an emphasis on epigenetic and transcriptional modulation.

IL-6-induced FOXO1 activity determines the dynamics of metabolism in CD8 T cells cross-primed by liver sinusoidal endothelial cells

Liver sinusoidal endothelial cells (LSECs) are liver-resident antigen (cross)-presenting cells that generate memory CD8 T cells, but metabolic properties of LSECs and LSEC-primed CD8 T cells remain understudied. Here, we report that high-level mitochondrial respiration and constitutive low-level glycolysis support LSEC scavenger and sentinel functions. LSECs fail to increase glycolysis and co-stimulation after TLR4 activation, indicating absence of metabolic and functional maturation compared with immunogenic dendritic cells. LSEC-primed CD8 T cells show a transient burst of oxidative phosphorylation and glycolysis. Mechanistically, co-stimulatory IL-6 signaling ensures high FOXO1 expression in LSEC-primed CD8 T cells, curtails metabolic activity associated with T cell activation, and is indispensable for T cell functionality after re-activation. Thus, distinct immunometabolic features characterize non-immunogenic LSECs compared with immunogenic dendritic cells and LSEC-primed CD8 T cells with memory features compared with effector CD8 T cells. This reveals local features of metabolism and function of T cells in the liver.

Combination Immune Checkpoint Blockade Enhances IL-2 and CD107a Production from HIV-Specific T Cells Ex Vivo in People Living with HIV on Antiretroviral Therapy

In people with HIV (PWH) on antiretroviral therapy (ART), immune dysfunction persists, including elevated expression of immune checkpoint (IC) proteins on total and HIV-specific T cells. Reversing immune exhaustion is one strategy to enhance the elimination of HIV-infected cells that persist in PWH on ART. We aimed to evaluate whether blocking CTL-associated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), T cell Ig domain and mucin domain 3 (TIM-3), T cell Ig and ITIM domain (TIGIT) and lymphocyte activation gene-3 (LAG-3) alone or in combination would enhance HIV-specific CD4⁺ and CD8⁺ T cell function ex vivo. Intracellular cytokine staining was performed using human PBMCs from PWH on ART (n = 11) and expression of CD107a, IFN-γ, TNF-α, and IL-2 was quantified with HIV peptides and Abs to IC. We found the following: 1) IC blockade enhanced the induction of CD107a and IL-2 but not IFN-γ and TNF-α in response to Gag and Nef peptides; 2) the induction of CD107a and IL-2 was greatest with multiple combinations of two Abs; and 3) Abs to LAG-3, CTLA-4, and TIGIT in combinations showed synergistic induction of IL-2 in HIV-specific CD8⁺ and CD107a and IL-2 production in HIV-specific CD4⁺ and CD8⁺ T cells. These results demonstrate that the combination of Abs to LAG-3, CTLA-4, or TIGIT can increase the frequency of cells expressing CD107a and IL-2 that associated with cytotoxicity and survival of HIV-specific CD4⁺ and CD8⁺ T cells in PWH on ART. These combinations should be further explored for an HIV cure.

Interleukin-18 Plays a Positive Feedback Activity to Natural Killer-Like B Cells in Hepatitis B Virus-Associated Acute-on-Chronic Liver Failure

Natural killer-like B (NKB) cells are a newly identified immune subset, which are separated from NK cells and B cells. NKB cells demonstrated immunoregulatory functions in elimination of microbial infection and inflammation through secretion of interleukin (IL)-12 and IL-18. However, the role of NKB cells in hepatitis B virus (HBV)-related diseases has not been reported. In this study, peripheral T cells, B cells, NK cells, and NKB cells in HBV-associated acute-on-chronic liver failure (ACLF), chronic hepatitis B (CHB), asymptomatic HBV carriers (AsC), and controls were investigated by flow cytometry. Plasma IL-12 and IL-18 levels were measured by enzyme-linked immunosorbent assay. Peripheral blood mononuclear cells from HBV-ACLF patients were stimulated with recombinant IL-12 or IL-18. Changes of immune cell percentage and nuclear factor-kappa B (NF-κB) phosphorylation were assessed. There were no statistical differences of T cell percentage, B cell percentage, or NK cell percentage among groups. NKB cell percentage within lymphocytes, and plasma IL-12 and IL-18 levels in HBV-ACLF patients were significantly elevated compared with in CHB, AsC, and controls. NKB cell percentage and IL-18, but not IL-12, had a better prognosis function for the 28-day survival status in HBV-ACLF patients. Recombinant IL-12 enhanced T cell and NK cell percentage, while only high concentrations (10 ng/mL) of IL-18 promoted NKB cell percentage in HBV-ACLF patients. High concentrations (10 ng/mL) of IL-18 induced NF-κB phosphorylation in NKB cells probably through suppression of IL-18 binding protein in HBV-ACLF patients. The current data indicated that elevated NKB cells and IL-18 might be important indicators for poor prognosis of HBV-ACLF patients. Increased IL-18 might play a positive feedback activity to NKB cells in HBV-ACLF patients.

Myeloid antigen-presenting cell niches sustain antitumor T cells and license PD-1 blockade via CD28 costimulation

The mechanisms regulating exhaustion of tumor-infiltrating lymphocytes (TIL) and responsiveness to PD-1 blockade remain partly unknown. In human ovarian cancer, we show that tumor-specific CD8+ TIL accumulate in tumor islets, where they engage antigen and upregulate PD-1, which restrains their functions. Intraepithelial PD-1+CD8+ TIL can be, however, polyfunctional. PD-1+ TIL indeed exhibit a continuum of exhaustion states, with variable levels of CD28 costimulation, which is provided by antigen-presenting cells (APC) in intraepithelial tumor myeloid niches. CD28 costimulation is associated with improved effector fitness of exhausted CD8+ TIL and is required for their activation upon PD-1 blockade, which also requires tumor myeloid APC. Exhausted TIL lacking proper CD28 costimulation in situ fail to respond to PD-1 blockade, and their response may be rescued by local CTLA-4 blockade and tumor APC stimulation via CD40L.

Induction of Unique STAT Heterodimers by IL-21 Provokes IL-1RI Expression on CD8+ T Cells, Resulting in Enhanced IL-1β Dependent Effector Function

IL-1β plays critical roles in the priming and effector phases of immune responses such as the differentiation, commitment, and memory formation of T cells. In this context, several reports have suggested that the IL-1β signal is crucial for CTL-mediated immune responses to viral infections and tumors. However, little is known regarding whether IL-1β acts directly on CD8⁺ T cells and what the molecular mechanisms underlying expression of IL-1 receptors (IL-1Rs) on CD8⁺ T cells and features of IL-1R⁺CD8⁺ T cells are. Here, we provide evidence that the expression of IL-1R type I (IL-1RI), the functional receptor of IL-1β, is preferentially induced by IL-21 on TCR-stimulated CD8⁺ T cells. Further, IL-1β enhances the effector function of CD8⁺ T cells expressing IL-21-induced IL-1RI by increasing cytokine production and release of cytotoxic granules containing granzyme B. The IL-21-IL-1RI-IL-1β axis is involved in an augmented effector function through regulation of transcription factors BATF, Blimp-1, and IRF4. Moreover, this axis confers a unique effector function to CD8⁺ T cells compared to conventional type 1 cytotoxic T cells differentiated with IL-12. Chemical inhibitor and immunoprecipitation assay demonstrated that IL-21 induces a unique pattern of STAT activation with the formation of both STAT1:STAT3 and STAT3:STAT5 heterodimers, which are critical for the induction of IL-1RI on TCR-stimulated CD8⁺ T cells. Taken together, we propose that induction of a novel subset of IL-1RI-expressing CD8⁺ T cells by IL-21 may be beneficial to the protective immune response against viral infections and is therefore important to consider for vaccine design.

JNJ-64794964 (AL-034/TQ-A3334), a TLR7 agonist, induces sustained anti-HBV activity in AAV/HBV mice via non-cytolytic mechanisms

JNJ-64794964 (JNJ-4964/AL-034/TQ-A3334), an oral toll-like receptor 7 agonist, is being investigated for the treatment of chronic hepatitis B (CHB), a condition with a high unmet medical need. The anti-hepatitis B (HBV) activity of JNJ-4964 was assessed preclinically in an adeno-associated virus vector expressing HBV (AAV/HBV) mouse model. Mice were treated orally with 2, 6 or 20 mg/kg of JNJ-4964 once-per-week for 12 weeks and then followed up for 4 weeks. At 6 mg/kg, a partial decrease in plasma HBV-DNA and plasma hepatitis B surface antigen (HBsAg) was observed, and anti-HBs antibodies and HBsAg-specific T cells were observed in 1/8 animals. At 20 mg/kg, plasma HBV-DNA and HBsAg levels were undetectable for all animals 3 weeks after start of treatment, with no rebound observed 4 weeks after JNJ-4964 treatment was stopped. High anti-HBs antibody levels were observed until 4 weeks after JNJ-4964 treatment was stopped. In parallel, HBsAg-specific immunoglobulin G-producing B cells and interferon-γ-producing CD4⁺ T cells were detected in the spleen. In 2/4 animals, liver HBV-DNA and HBV-RNA levels and liver hepatitis B core antigen expression dropped 4 weeks after JNJ-4964 treatment-stop. In these animals, HBsAg-specific CD8⁺ T cells were detectable. Throughout the study, normal levels of alanine aminotransferase were observed, with no hepatocyte cell death (end of treatment and 4 weeks later) and minimal infiltrations of B and T cells into the liver, suggesting induction of cytokine-mediated, non-cytolytic mechanisms.

Application of a newly-developed cynomolgus macaque BiTE-mediated cytotoxic T-lymphocyte activity assay to various immunomodulatory agents in vitro

The immunotoxic potential of drug candidates is assessed through the examination of results from a variety of in vitro and in vivo immunophenotyping and functional study endpoints in pre-clinical studies. CD8⁺ cytotoxic T-lymphocyte (CTL) activity impairment by immunosuppressive agents is recognized to be a potentiating factor for decreased antiviral defense and increased cancer risk. A bi-specific T-cell engager (BiTE^®)-mediated CTL activity assay that applies to ex vivo experimentation in non-human primates in the context of toxicology studies was successfully developed and applied in cynomolgus monkey regulatory studies. While an ex vivo analysis conducted in the context of repeat-dose toxicology studies focuses on the long-term impact on CTL function, an in vitro assay with the same experimental design captures acute effects in the presence of the test article. Here, the in vitro assay was applied to a list of drugs with known clinical immunomodulatory impact to understand the applicability of the assay. The results showed this assay was sensitive to a wide range of immunosuppressants directly targeting cell-intrinsic signaling pathways in activated CTL. However, agents executing immuno-modulation through inhibiting cytokines/cytokine receptors, co-stimulatory molecules, and cell adhesion and migration pathways did not impair the CTL activity in this short-term in vitro culture. In addition, anti-PD-1/PD-L1 immune checkpoint blockers enhanced the CTL activity. Taken together, the results here demonstrate that in concordance with their mechanism of action, the in vitro BiTE^®-mediated CTL assay is applicable and sensitive to immunomodulatory agents acting via a variety of mechanisms.

Functional Exhaustion of HBV-Specific CD8 T Cells Impedes PD-L1 Blockade Efficacy in Chronic HBV Infection

Background

A functional cure for chronic HBV could be achieved by boosting HBV-specific immunity. In vitro studies show that immunotherapy could be an effective strategy. However, these studies include strategies to enrich HBV-specific CD8 T cells, which could alter the expression of the anti-PD-1/anti-PD-L1 antibody targets. Our aim was to determine the efficacy of PD-L1 blockade ex vivo.

Methods

HBV-specific CD8 T cells were characterized ex vivo by flow cytometry for the simultaneous analysis of six immune populations and 14 activating and inhibitory receptors. Ex vivo functionality was quantified by ELISpot and by combining peptide pool stimulation, dextramers and intracellular flow cytometry staining.

Results

The functionality of HBV-specific CD8 T cells is associated with a higher frequency of cells with low exhaustion phenotype (LAG3^-TIM3^-PD-1⁺), independently of the clinical parameters. The accumulation of HBV-specific CD8 T cells with a functionally exhausted phenotype (LAG3⁺TIM3⁺PD-1⁺) is associated with lack of ex vivo functionality. PD-L1 blockade enhanced the HBV-specific CD8 T cell response only in patients with lower exhaustion levels, while response to PD-L1 blockade was abrogated in patients with higher frequencies of exhausted HBV-specific CD8 T cells.

Conclusion

Higher levels of functionally exhausted HBV-specific CD8 T cells are associated with a lack of response that cannot be restored by blocking the PD-1:PD-L1 axis. This suggests that the clinical effectiveness of blocking the PD-1:PD-L1 axis as a monotherapy may be restricted. Combination strategies, potentially including the combination of anti-LAG-3 with other anti-iR antibodies, will likely be required to elicit a functional cure for patients with high levels of functionally exhausted HBV-specific CD8 T cells.

Prospects for the Global Elimination of Hepatitis B

Chronic hepatitis B virus (HBV) infection is the leading cause of liver cirrhosis and hepatocellular carcinoma, estimated to be globally responsible for ∼800,000 deaths annually. Although effective vaccines are available to prevent new HBV infection, treatment of existing chronic hepatitis B (CHB) is limited, as the current standard-of-care antiviral drugs can only suppress viral replication without achieving cure. In 2016, the World Health Organization called for the elimination of viral hepatitis as a global public health threat by 2030. The United States and other nations are working to meet this ambitious goal by developing strategies to cure CHB, as well as prevent HBV transmission. This review considers recent research progress in understanding HBV pathobiology and development of therapeutics for the cure of CHB, which is necessary for elimination of hepatitis B by 2030.

Unraveling the Multifaceted Nature of CD8 T Cell Exhaustion Provides the Molecular Basis for Therapeutic T Cell Reconstitution in Chronic Hepatitis B and C

In chronic hepatitis B and C virus infections persistently elevated antigen levels drive CD8+ T cells toward a peculiar differentiation state known as T cell exhaustion, which poses crucial constraints to antiviral immunity. Available evidence indicates that T cell exhaustion is associated with a series of metabolic and signaling deregulations and with a very peculiar epigenetic status which all together lead to reduced effector functions. A clear mechanistic network explaining how intracellular metabolic derangements, transcriptional and signaling alterations so far described are interconnected in a comprehensive and unified view of the T cell exhaustion differentiation profile is still lacking. Addressing this issue is of key importance for the development of innovative strategies to boost host immunity in order to achieve viral clearance. This review will discuss the current knowledge in HBV and HCV infections, addressing how innate immunity, metabolic derangements, extensive stress responses and altered epigenetic programs may be targeted to restore functionality and responsiveness of virus-specific CD8 T cells in the context of chronic virus infections.

Follicular Helper T (TFH) Cell Targeting by TLR8 Signaling For Improving HBsAg-Specific B Cell Response In Chronic Hepatitis B Patients

Identifying signaling pathways that induce B cell response can aid functional cure strategies for chronic hepatitis B infection (CHB). TLR8 activation with ssRNA was shown to enhance follicular helper T cell (T_FH) function leading to improved B cell responses in vitro. We investigated whether this mechanism can rescue an exhausted immune response in CHB infection. Effect of TLR8 agonism on supporting cytokines and T_FH and B cells were evaluated using ex vivo and in vitro assays. The ability of an oral TLR8 agonist to promote T_FH and B cell response was tested in samples from phase 1b clinical trial. TLR8 agonism induced T_FH polarizing cytokine IL-12 in monocytes. Treatment of peripheral blood mononuclear cells (PBMCs) from CHB patients with TLR8 agonists induced cytokine IL-21 by T_FH cells with enhanced IL-21⁺BCL-6⁺ and ICOS⁺BCL-6⁺ co-expression. Mechanistically, incubation of isolated naïve CD4⁺ T cells with TLR8 triggered monocytes resulted in their differentiation into IL-21⁺ICOS⁺BCL-6⁺ T_FH in an IL-12 dependent manner. Furthermore, co-culture of these IL-21 producing T_FH with autologous naïve B cells led to enhanced memory (CD19⁺CD27⁺) and plasma B cell generation (CD19⁺CD27⁺⁺CD38⁺) and IgG production. Importantly, in T_FH from CHB patients treated with an oral TLR8 agonist, HBsAg-specific BCL-6, ICOS, IL-21 and CD40L expression and rescue of defective activation induced marker (AIM) response along with partial restoration of HBsAg-specific B cell ELISPOT response was evident. TLR8 agonism can thus enhance HBV-specific B cell responses in CHB patients by improving monocyte-mediated T_FH function and may play a role in achieving HBV functional cure.

Association Between Serum IL-6, IL-10, IL-12, and IL-23 Levels and Severity of Liver Cirrhosis

Background

Liver cirrhosis contributes to high liver-related mortality globally. Systemic inflammation mediated by immune cells contributes to the progression of liver cirrhosis. Growing evidence shows that several pro- and anti-inflammatory cytokines might have an important role in liver cirrhosis.

Objective

To evaluate the association between serum IL-6, IL-10, IL-12, and IL-23 levels and severity of liver cirrhosis.

Methods

This observational study was carried out at the Department of Internal Medicine, Universitas Sumatera Utara, Indonesia from March 2018 to August 2019. The severity of liver cirrhosis was assessed by using the Child-Pugh score. IL-6, IL-10, IL-12, and IL-23 levels, hepatitis and renal function were measured in all study subjects. Independent t-test and Mann-Whitney tests were conducted to observe differences between groups.

Results

A total of 78 liver cirrhosis patients were enrolled, mean age was 50.6±11.4. Median serum IL-6, IL-10, IL-12, and IL-23 levels were 24.5(2.6-46.4)pg/ml, 2.1(0.4-9.3)pg/ml, 3.5(1.4-20.8)pg/ml and 20.3(9.2-218)pg/ml, respectively. A higher IL-6 level was associated with more severe liver cirrhosis (p=0.001) and the presence of hepatic encephalopathy (p=0.018). Higher IL-23 level was found in patients with no hepatic encephalopathy (p=0.049). There was no association between serum cytokines levels and hepatitis viral infection status.

Conclusion

IL-6 is associated with the severity of liver cirrhosis.

Shared immunotherapeutic approaches in HIV and hepatitis B virus: combine and conquer

PURPOSE OF REVIEW

The aim of this study was to identify similarities, differences and lessons to be shared from recent progress in HIV and hepatitis B virus (HBV) immunotherapeutic approaches.

RECENT FINDINGS

Immune dysregulation is a hallmark of both HIV and HBV infection, which have shared routes of transmission, with approximately 10% of HIV-positive patients worldwide being coinfected with HBV. Immune modulation therapies to orchestrate effective innate and adaptive immune responses are currently being sought as potential strategies towards a functional cure in both HIV and HBV infection. These are based on activating immunological mechanisms that would allow durable control by triggering innate immunity, reviving exhausted endogenous responses and/or generating new immune responses. Recent technological advances and increased appreciation of humoral responses in the control of HIV have generated renewed enthusiasm in the cure field.

SUMMARY

For both HIV and HBV infection, a primary consideration with immunomodulatory therapies continues to be a balance between generating highly effective immune responses and mitigating any significant toxicity. A large arsenal of new approaches and ongoing research offer the opportunity to define the pathways that underpin chronic infection and move closer to a functional cure.

Chitosan Nanovaccines as Efficient Carrier Adjuvant System for IL-12 with Enhanced Protection Against HBV

Purpose

Alum adjuvant in HBV prophylactic vaccines is poor in inducing cellular immunity with the inhibition of IL-12 secretion, and approximately 5–10% of immunised individuals fail to clear HBV upon infection. IL-12 plasmids (pIL-12) as adjuvants enhance significant humoral and cellular immune response in vaccines. However, finding a novel delivery system to protect pIL-12 from enzymatic degradation and achieve efficient delivery remains a major challenge.

Methods

We prepared the chitosan nanovaccine-loaded IL-12 expression plasmid (termed as “Ng(-)pIL-12”) and analysed the physicochemical properties, encapsulation efficiency and safety. Then, we evaluated the efficiency of Ng(-)pIL-12 for prophylactic HBV vaccine. Serum samples were collected and analysed for IL-12, HBsAg, anti-HBs IgG, IgG1 and IgG2b. Liver tissues were collected and analysed for HBV DNA and RNA. BMDCs and lymphocytes were collected and analysed for HBV-specific immune responses. To further confirm the long-term protective immune response against HBV, these immunised mice were challenged with hydrodynamic injection of pAAV/HBV 1.2 plasmid on day 56 after the initiation of immunisation.

Results

Chitosan nanovaccine prepared with CS and γ-PGA could load pIL-12 effectively and safely, and IL-12 was efficiently produced in vivo. Interestingly, Ng(-)pIL-12 adjuvant combined with HBsAg induced higher levels of anti-HBs IgG, IgG1 and IgG2b, promoted maturation and presentation capacity of DCs, especially CD8α⁺/CD103⁺ DCs. Meanwhile, Ng(-)pIL-12 adjuvant generated robust HBV-specific CD8⁺ T and CD4⁺ T cell responses. More importantly, Ng(-)pIL-12 adjuvant triggered terminally differentiated effector memory responses with strong anti-HBV effects.

Conclusion

Chitosan nanovaccines as an efficient carrier adjuvant system for pIL-12 combined with HBsAg induced protective anti-HBs IgG and enhanced HBV-specific CD8⁺ T and CD4⁺ T cell responses, and achieved long-term memory response against HBV, making it a promising candidate for prophylactic HBV vaccines.

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Therapeutic Potential of TLR8 Agonist GS-9688 (Selgantolimod) in Chronic Hepatitis B: Remodeling of Antiviral and Regulatory Mediators

BACKGROUND AND AIMS

GS-9688 (selgantolimod) is a toll-like receptor 8 agonist in clinical development for the treatment of chronic hepatitis B (CHB). Antiviral activity of GS-9688 has previously been evaluated in vitro in HBV-infected hepatocytes and in vivo in the woodchuck model of CHB. Here we evaluated the potential of GS-9688 to boost responses contributing to viral control and to modulate regulatory mediators.

APPROACH AND RESULTS

We characterized the effect of GS-9688 on immune cell subsets in vitro in peripheral blood mononuclear cells of healthy controls and patients with CHB. GS-9688 activated dendritic cells and mononuclear phagocytes to produce IL-12 and other immunomodulatory mediators, inducing a comparable cytokine profile in healthy controls and patients with CHB. GS-9688 increased the frequency of activated natural killer (NK) cells, mucosal-associated invariant T cells, CD4+ follicular helper T cells, and, in about 50% of patients, HBV-specific CD8+ T cells expressing interferon-γ. Moreover, in vitro stimulation with GS-9688 induced NK-cell expression of interferon-γ and TNF-α, and promoted hepatocyte lysis. We also assessed whether GS-9688 inhibited immunosuppressive cell subsets that might enhance antiviral efficacy. Stimulation with GS-9688 reduced the frequency of CD4+ regulatory T cells and monocytic myeloid-derived suppressor cells (MDSCs). Residual MDSCs expressed higher levels of negative immune regulators, galectin-9 and programmed death-ligand 1. Conversely, GS-9688 induced an expansion of immunoregulatory TNF-related apoptosis-inducing ligand+ NK cells and degranulation of arginase-I+ polymorphonuclear MDSCs.

CONCLUSIONS

GS-9688 induces cytokines in human peripheral blood mononuclear cells that are able to activate antiviral effector function by multiple immune mediators (HBV-specific CD8+ T cells, CD4+ follicular helper T cells, NK cells, and mucosal-associated invariant T cells). Although reducing the frequency of some immunoregulatory subsets, it enhances the immunosuppressive potential of others, highlighting potential biomarkers and immunotherapeutic targets to optimize the antiviral efficacy of GS-9688.

Natural Killer Cells and T Cells in Hepatocellular Carcinoma and Viral Hepatitis: Current Status and Perspectives for Future Immunotherapeutic Approaches

Natural killer (NK) cells account for 25–50% of the total number of hepatic lymphocytes, which implicates that NK cells play an important role in liver immunity. The frequencies of both circulating and tumor infiltrating NK cells are positively correlated with survival benefit in hepatocellular cancer (HCC) and have prognostic implications, which suggests that functional impairment in NK cells and HCC progression are strongly associated. In HCC, T cell exhaustion is accompanied by the interaction between immune checkpoint ligands and their receptors on tumor cells and antigen presenting cells (APC). Immune checkpoint inhibitors (ICIs) have been shown to interfere with this interaction and have altered the therapeutic landscape of multiple cancer types including HCC. Immunotherapy with check-point inhibitors, aimed at rescuing T-cells from exhaustion, has been applied as first-line therapy for HCC. NK cells are the first line effectors in viral hepatitis and play an important role by directly eliminating virus infected cells or by activating antigen specific T cells through IFN-γ production. Furthermore, chimeric antigen receptor (CAR)-engineered NK cells and T cells offer unique opportunities to create CAR-NK with multiple specificities learning from the experience gained with CAR-T cells with potentially less adverse effects. This review focus on the abnormalities of NK cells, T cells, and their functional impairment in patients with chronic viral hepatitis, which contributes to progression to hepatic malignancy. Furthermore, we discuss and summarize recent advances in the NK cell and T cell based immunotherapeutic approaches in 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.

IFN-α Suppresses Myeloid Cytokine Production, Impairing IL-12 Production and the Ability to Support T-Cell Proliferation

BACKGROUND

Interferon-α (IFN-α) can suppress production of T-cell polarizing cytokines or induce inhibitory antigen-presenting cells that suppress T-cell activation. Previous studies showed that IFN-α therapy fails to boost virus-specific T-cell immunity in patients with chronic hepatitis B virus infection. Our aim was to determine whether IFN-α exposure alters human antigen-presenting cell function in vivo.

METHODS

We investigated the immunomodulatory effects using peripheral blood mononuclear cells from healthy donors exposed to IFN-α and chronic hepatitis B (CHB) patients starting IFN-α therapy.

RESULTS

IFN-α increased HLA-DR, CD80, CD86, and PD-L1 expression on healthy donor monocytes. In contrast to the activated phenotype, IFN-α inhibited Toll-like receptor-induced cytokine production and monocyte-induced T-cell proliferation. In CHB patients, peg-IFN treatment induced an interferon-stimulated gene signature in monocytes and increased HLA-DR, CD80, CD86, and PD-L1 expression. As early as 3 days after CHB patients started treatment, IFN-α inhibited monocyte cytokine production and T-cell stimulation ex vivo. IFN-α-mediated inhibition of IL-12 production, rather than inhibitory receptor expression, was responsible for inhibition of T-cell proliferation. Addition of IL-12 restored T-cell proliferation to baseline levels.

CONCLUSIONS

Understanding how professional antigen-presenting cells respond to immunomodulation is important for both new innate and adaptive-targeted immunotherapies.

CLINICAL TRIALS REGISTRATION

NCT00962871.