Hepatic immune regulation and its involvement in viral hepatitis infection

Hepatitis B Virus DNA integration: Implications for diagnostics, therapy, and outcome

HBV DNA integration originally recognized as a non-functional byproduct of the HBV life cycle has now been accepted as a significant contributor to HBV pathogenesis and HDV persistence. Integrated HBV DNA is derived from linear genomic DNA present in virus particles or produced from aberrantly processed relaxed circular genomic DNA following an infection, and can drive expression of HBsAg and HBx. DNA integration events accumulate over the course of viral infection ranging from a few percent during early phases to nearly 100 percent of infected cells after prolonged chronic infection. HBV DNA integration events have primarily been investigated in the context of HCC development where they can activate known oncogenes and other growth promoting genes, cause chromosomal instability and presumably epigenetic alterations promoting tumor growth. More recent evidence suggests that HBsAg expression from integrated DNA might contribute to HBV pathogenesis by attenuating the immune response. Integrated DNA provides a source for envelope proteins required for HDV replication and hence represents a means for HDV persistence. Because integrated DNA is responsible for persistence of HBsAg in the absence of viral replication it impacts established criteria for the resolution of HBV infection which relies on HBsAg as a diagnostic marker. Integrated HBV DNA has been useful in assessing the turnover of infected hepatocytes which occurs during all phases of chronic hepatitis B including the initial phase of infection historically termed immune tolerant. HBV DNA integration was also shown to impact the development of novel therapies targeting viral RNAs.

Liver metastases across cancer types sharing tumor environment immunotolerance can impede immune response therapy and immune monitoring

BACKGROUND

Hepatic immune tolerance might contribute to the development of therapeutic resistance to immunotherapy. However, addressing this issue is challenging since the efficacy of immunotherapy in the context of liver metastasis (LM) remains poorly studied. Here, we aimed to establish an LM common immune feature (LMCIF) score to quantify the characteristics of LM immunotolerance across cancer types for assisting clinical disease management.

METHODS

Large-scale clinical data were collected to identify the prognosis of LM. Multi-omics datasets of metastatic cancers with LM special immune-related pathways (LMSIPs) from the Molecular Signatures Database (MSigDB)were used to obtain an LMCIF cluster. Based on differential expression genes (DEGs), a novel LMCIF score for the LMCIF cluster was constructed. In addition, multi-omics, and immunohistochemistry (IHC) data from the public and in-house cohorts were used to explore the features of LM, and LMCIF score.

RESULTS

Patients with LM had a worse prognosis and significantly lower infiltration of immune cells than patients with metastasis to other organs when analyzed with combined clinical and RNA sequencing data. After extracting the LMCIF cluster from 373 samples by utilizing 29 LMSIPs and validating them in a microarray cohort, an LMCIF score was established to confirm the role of the immunosuppressive environment as a contributor to the poor prognosis of LM across cancer types. Moreover, this LMCIF score could be used to predict the immune response of cancer patients undergoing immunotherapy. Finally, we identified that the majority of the 31 LMCIF genes exhibited a negative correlation with TME cells in LM patients, one of them, KRT19, which possessed the strongest positive correlation with LMCIF score, was confirmed to have an immunosuppressive effect through IHC analysis.

CONCLUSIONS

Our results suggest that LM across cancer types share similar immunological profiles that induce immunotolerance and escape from immune monitoring. The novel LMCIF score represents a common liver metastasis immune cluster for predicting immunotherapy response, the results of which might benefit clinical disease management.

Impact of baseline hepatitis B virus viral load on the long-term prognosis of advanced hepatocellular carcinoma treated with immunotherapy

BACKGROUND

Although the combination of lenvatinib and PD-1 inhibitors has become the standard regimen for the treatment of advanced hepatocellular carcinoma (HCC), real data on the impact of baseline hepatitis B virus (HBV)-DNA levels on the clinical efficacy of this regimen is still limited.

AIM

To evaluate the effectiveness of camrelizumab combined with lenvatinib in patients with HCC at varying levels of HBV-DNA.

METHODS

One hundred and twenty patients with HCC who received camrelizumab and lenvatinib treatment were categorized into two cohorts: HBV-DNA ≤ 2000 (n = 66) and HBV-DNA > 2000 (n = 54). The main outcomes measured were overall survival (OS) and progression-free survival (PFS), while additional outcomes included the rate of objective response rate (ORR), disease control rate (DCR), and any negative events. Cox proportional hazards regression analysis revealed independent predictors of OS, leading to the creation of a nomogram incorporating these variables.

RESULTS

The median PFS was 8.32 months for the HBV-DNA ≤ 2000 group, which was similar to the 7.80 months observed for the HBV DNA > 2000 group (P = 0.88). Likewise, there was no notable variation in the median OS between the two groups, with durations of 13.30 and 14.20 months respectively (P = 0.14). The ORR and DCR were compared between the two groups, showing ORR of 19.70% vs 33.33% (P = 0.09) and DCR of 72.73% vs 74.07% (P = 0.87). The nomogram emphasized the importance of antiviral treatment as the main predictor of patient results, with portal vein tumor thrombus and Barcelona Clinic Liver Cancer staging following closely behind.

CONCLUSION

The clinical outcomes of patients with HBV-associated HCC treated with camrelizumab in combination with lenvatinib are not significantly affected by HBV viral load.

Impact of baseline hepatitis B virus viral load on the long-term prognosis of advanced hepatocellular carcinoma treated with immunotherapy

BACKGROUND

Although the combination of lenvatinib and PD-1 inhibitors has become the standard regimen for the treatment of advanced hepatocellular carcinoma (HCC), real data on the impact of baseline hepatitis B virus (HBV)-DNA levels on the clinical efficacy of this regimen is still limited.

AIM

To evaluate the effectiveness of camrelizumab combined with lenvatinib in patients with HCC at varying levels of HBV-DNA.

METHODS

One hundred and twenty patients with HCC who received camrelizumab and lenvatinib treatment were categorized into two cohorts: HBV-DNA ≤ 2000 (n = 66) and HBV-DNA > 2000 (n = 54). The main outcomes measured were overall survival (OS) and progression-free survival (PFS), while additional outcomes included the rate of objective response rate (ORR), disease control rate (DCR), and any negative events. Cox proportional hazards regression analysis revealed independent predictors of OS, leading to the creation of a nomogram incorporating these variables.

RESULTS

The median PFS was 8.32 months for the HBV-DNA ≤ 2000 group, which was similar to the 7.80 months observed for the HBV DNA > 2000 group (P = 0.88). Likewise, there was no notable variation in the median OS between the two groups, with durations of 13.30 and 14.20 months respectively (P = 0.14). The ORR and DCR were compared between the two groups, showing ORR of 19.70% vs 33.33% (P = 0.09) and DCR of 72.73% vs 74.07% (P = 0.87). The nomogram emphasized the importance of antiviral treatment as the main predictor of patient results, with portal vein tumor thrombus and Barcelona Clinic Liver Cancer staging following closely behind.

CONCLUSION

The clinical outcomes of patients with HBV-associated HCC treated with camrelizumab in combination with lenvatinib are not significantly affected by HBV viral load.

The lack of HBsAg secretion does neither facilitate induction of antiviral T cell responses nor Hepatitis B Virus clearance in mice

Immune tolerance to the hepatitis B virus (HBV) is crucial for developing chronic hepatitis B, and the HBV surface antigen (HBsAg) produced and secreted in high amounts is regarded as a key contributor. HBsAg is expressed in HBV-infected hepatocytes and those carrying an HBV integration. Whether either HBsAg secretion or the high antigen amount expressed in the liver determines its immunomodulatory properties, however, remains unclear. We, therefore, developed a novel HBV animal model that allowed us to study the role of secreted HBsAg. We introduced a previously described HBs mutation, C65S, abolishing HBsAg secretion into a replication-competent 1.3-overlength HBV genome and used adeno-associated virus vectors to deliver it to the mouse liver. The AAV-HBV established a carrier state of wildtype and C65S mutant HBV, respectively. We investigated antiviral B- and T-cell immunity in the HBV-carrier mice after therapeutic vaccination. Moreover, we compared the effect of a lacking HBsAg secretion with that of an antiviral siRNA. While missing HBsAg secretion allowed for higher levels of detectable anti-HBs antibodies after therapeutic vaccination, it did neither affect antiviral T-cell responses nor intrahepatic HBV gene expression, irrespective of the starting level. A treatment with HBV siRNA restricting viral antigen expression within hepatocytes, however, improved the antiviral efficacy of therapeutic vaccination, irrespective of the ability of HBV to secrete HBsAg. Our data indicate that clearing HBsAg from blood cannot significantly impact HBV persistence or T-cell immunity. This indicates that a restriction of hepatic viral antigen expression will be required to break HBV immunotolerance.

Immune Checkpoint Inhibitors in Hepatocellular Carcinoma and Their Hepatic-Related Side Effects: A Review

Primary liver cancer is one of the leading causes of cancer mortality worldwide, with hepatocellular carcinoma (HCC) being the most prevalent type of liver cancer. The prognosis of patients with advanced, unresectable HCC has historically been poor. However, with the emergence of immunotherapy, specifically immune checkpoint inhibitors (ICIs), there is reason for optimism. Nevertheless, ICIs do not come without risk, especially when administered in patients with HCC, given their potential underlying poor hepatic reserve. Given their novelty in the management of HCC, there are few studies to date specifically investigating ICI-related side effects on the liver in patients with underlying HCC. This review will serve as a guide for clinicians on ICIs' role in the management of HCC and their potential side effect profile. There will be a discussion on ICI-related hepatotoxicity, the potential for hepatitis B and C reactivation with ICI use, the potential for the development of autoimmune hepatitis with ICI use, and the risk of gastrointestinal bleeding with ICI use. As ICIs become more commonplace as a treatment option in patients with advanced HCC, it is imperative that clinicians not only understand the mechanism of action of such agents but also understand and are able to identify hepatic-related side effects.

Hepatitis B virus reactivation in hepatocellular carcinoma patients after hepatic arterial infusion chemotherapy combined with and without immunotherapy

BACKGROUND

Hepatitis B virus (HBV) reactivation (HBVr) is a major concern for hepatocellular carcinoma (HCC) patients undergoing hepatic arterial infusion chemotherapy (HAIC) using mFOLFOX6 regimen. There is insufficient evidence to support the routine use of HAIC combined with immunotherapy in HCC patients with HBVr. The aim of this study was to examine the adverse events (AEs) related to HBVr in HCC patients after HAIC, with or without immunotherapy, and to assess the effectiveness of antiviral prophylaxis for HBVr.

METHODS

Medical records of HCC patients receiving HAIC combined with and without immunotherapy between January 2021 and June 2023 were reviewed. The patients were divided into two groups based on whether they received immunotherapy or not.

RESULTS

Out of the 106 patients, 32 (30.2%) developed HBVr. Among these, 23 eligible patients with HBVr were included, with 14 patients (61%) receiving immunotherapy and nine patients (39%) not receiving immunotherapy. Prior to HAIC treatment, four patients in each group had detectable HBV DNA with median titre of 3.66 × 102 IU/ml (patients with immunotherapy) and 1.98 × 102 IU/ml (patients without immunotherapy), respectively. Fifteen patients did not show detectable HBV DNA. At HBVr occurrence, the median HBV DNA level was 6.95 × 102 IU/ml for all patients, 4.82 × 102 IU/ml in patients receiving immunotherapy and 1.3 × 103 IU/ml in patients not receiving immunotherapy. Grade 3 hepatitis developed in 12 cases of all patients (12/23, 48%), including five patients with immunotherapy (56%) and seven patients without immunotherapy (78%). At the 3-month follow-up, HBV DNA was detected in 10 patients, with a median HBV DNA level of 2.05 × 102 IU/ml (range, 1.5 × 102- 3.55 × 102 IU/ml) in patients (7/10) with immunotherapy and 4.28 × 102 IU/ml (range, 1.15 × 102- 5.88 × 102 IU/ml) in patients (3/10) without immunotherapy. Intensified antiviral treatment was administered to all patients. No HBVr-related fatal events occurred.

CONCLUSION

HBVr can occur after HAIC combined with or without immunotherapy. The degree of liver damage did not differ significantly in patients treated with or without immunotherapy. Intensified antiviral treatment was found to be crucial for HCC patients with HBVr.

Longterm Outcome of Therapeutic Vaccination with a Third Generation Pre-S/S HBV Vaccine (PreHevbrioR) of Chronically HBV Infected Patients

Several antiviral treatment regimens for chronic hepatitis B (CHB) virus infection have been shown to be effective in suppressing viral load and reducing the risk of hepatocellular injury and its complications. It has been hypothesized that high levels of circulating HBV surface antigen(s) may lead to immune tolerance against HBV and contribute to chronic carriership. Conversely, low-level HBsAg may create a window for the reconstitution of an HBV-specific immune response through vaccination and control of infection. Previous studies in non-responders to yeast-derived HBV vaccines, using a third-generation pre-S/S vaccine, have led to up to 95% anti-HBs seroconversion. This report evaluates the long-term outcome after experimental vaccination with a pre-S/S HBV vaccine intended as a therapeutic intervention in chronic HBV carriers. Four low-level HBsAg carriers (<500 IU/mL) were vaccinated three to seven times with 20 μg PreHevbrioR. Three out of four carriers eliminated HBsAg completely and seroconverted to anti-HBs. One patient seroconverted to anti-HBs but remained with a borderline HBsAg titer (10 IU/mL). Serum anti-HBs levels following repeated vaccination varied between 27 and >1000 IU/L, respectively. Long-term observation (>6 years) showed that after discontinuing NUC treatment for at least two years, HBsAg and HBV DNA remained negative with anti-HBs positive titers ranging between 80 and >1000 IU/L. Based on our preliminary observations, there is a rationale to further evaluate the role of this vaccine as a therapeutic agent.

The occurrence of immune-related adverse events is an independent risk factor both for serum HBsAg increase and HBV reactivation in HBsAg-positive cancer patients receiving PD-1 inhibitor combinational therapy

Background

Previous studies have suggested the potential of PD-1/PD-L1 inhibitors in the treatment of chronic HBV infection. However, since phase III clinical trials have not yet been announced, additional clinical insights may be obtained by observing changes in serum hepatitis B surface antigen (HBsAg) and HBV-DNA levels in cancer patients undergoing PD-1 inhibitor therapy.

Objective

To explore the effects of PD-1 inhibitor combinational therapy on serum HBsAg and HBV-DNA levels, investigate the incidence of HBsAg loss, HBV reactivation (HBVr), and immune-related adverse events (irAEs), and identify the risk factors associated with significant HBsAg fluctuations and HBVr.

Methods

A retrospective study including 1195 HBsAg-positive cancer patients who received PD-1 inhibitors between July 2019 and June 2023 was conducted, and 180 patients were enrolled in this study. Serum HBsAg levels before and after PD-1 inhibitor administration were compared across different subgroups. The Pearson χ2 or Fisher exact test was performed to investigate the relationships between categorical variables. Univariable and multivariable analysis were performed to identify the risk factors associated with significant HBsAg fluctuations and HBVr.

Results

With the concurrent use of antiviral agents, serum HBsAg levels decreased (Z=-3.966, P < 0.0001) in 129 patients and increased (t=-2.047, P=0.043) in 51 patients. Additionally, 7 patients (3.89%) achieved serum HBsAg loss. Virus replication was suppressed in most of the enrolled patients. When divided patients into different subgroups, significant HBsAg decreases after PD-1 inhibitor administration were discovered in lower baseline HBsAg group (Z=-2.277, P=0.023), HBeAg-seronegative group (Z=-2.200, P=0.028), non-irAEs occurrence group (Z=-2.007, P=0.045) and liver cancer group (Z=-1.987, P=0.047). Of note, 11 patients and 36 patients experienced HBVr (6.11%) and irAEs (20%), respectively, which could lead to discontinuation or delayed use of PD-1 inhibitors. After multivariable analysis, HBeAg-seropositive (OR, 7.236 [95% CI, 1.757-29.793], P=0.01) and the occurrence of irAEs (OR, 4.077 [95% CI, 1.252-13.273], P=0.02) were identified as the independent risk factors for significant HBsAg increase, the occurrence of irAEs (OR, 5.560 [95% CI, 1.252-13.273], P=0.01) was identified as the only independent risk factor for HBVr.

Conclusion

PD-1 inhibitors combined with nucleos(t)ide analogues (NAs) may exert therapeutic potential for chronic HBV infection in cancer patients. However, attention also should be paid to the risk of significant elevation in HBsAg levels, HBVr, and irAEs associated with PD-1 inhibitor combinational therapy.

A gene expression profile-based approach to screen the occurrence and predisposed host characteristics of drug-induced liver injury: a case study of Psoralea corylifolia Linn

Drug-induced liver injury (DILI) is one of the most common causes of a drug being withdrawn, and identifying the culprit drugs and the host factors at risk of causing DILI has become a current challenge. Recent studies have found that immune status plays a considerable role in the development of DILI. In this study, DILI-related differentially expressed genes mediated by immunoinflammatory cytokines were obtained from the Gene Expression Omnibus (GEO) database to predict the occurrence of DILI (named the DILI predictive gene set, DILI_PGS), and the predictability of the DILI_PGS was verified using the Connectivity Map (CMap) and LiverTox platforms. The results obtained DILI_PGS from the GEO database could predict 81.25% of liver injury drugs. In addition, the Coexpedia platform was used to predict the DILI_PGS-related characteristics of common host diseases and found that the DILI_PGS mainly involved immune-related diseases and tumor-related diseases. Then, animal models of immune stress (IS) and immunosuppressive (IP) were selected to simulate the immune status of the above diseases. Meanwhile, psoralen, a main component derived from Psoralea corylifolia Linn. with definite hepatotoxicity, was selected as an experimental drug with highly similar molecular fingerprints to three idiosyncratic hepatotoxic drugs (nefazodone, trovafloxacin, and nimesulide) from the same DILI_PGS dataset. The animal experiment results found a single administration of psoralen could significantly induce liver injury in IS mice, while there was no obvious liver function change in IP mice by repeatedly administering the same dose of psoralen, and the potential mechanism of psoralen-induced liver injury in IS mice may be related to regulating the expression of the TNF-related pathway. In conclusion, this study constructed the DILI_PGS with high accuracy to predict the occurrence of DILI and preliminarily identified the characteristics of host factors inducing DILI.

Liver in infections: a single-cell and spatial transcriptomics perspective

The liver is an immune organ that plays a vital role in the detection, capture, and clearance of pathogens and foreign antigens that invade the human body. During acute and chronic infections, the liver transforms from a tolerant to an active immune state. The defence mechanism of the liver mainly depends on a complicated network of intrahepatic and translocated immune cells and non-immune cells. Therefore, a comprehensive liver cell atlas in both healthy and diseased states is needed for new therapeutic target development and disease intervention improvement. With the development of high-throughput single-cell technology, we can now decipher heterogeneity, differentiation, and intercellular communication at the single-cell level in sophisticated organs and complicated diseases. In this concise review, we aimed to summarise the advancement of emerging high-throughput single-cell technologies and re-define our understanding of liver function towards infections, including hepatitis B virus, hepatitis C virus, Plasmodium, schistosomiasis, endotoxemia, and corona virus disease 2019 (COVID-19). We also unravel previously unknown pathogenic pathways and disease mechanisms for the development of new therapeutic targets. As high-throughput single-cell technologies mature, their integration into spatial transcriptomics, multiomics, and clinical data analysis will aid in patient stratification and in developing effective treatment plans for patients with or without liver injury due to infectious diseases.

The safety concerns regarding immune checkpoint inhibitors in liver cancer patients rising mainly from CHB

Aim: To analyze the safety of immune checkpoint inhibitors in primary liver cancer patients and to identify the risk factors for immune-related adverse events (irAEs). Methods: The study enrolled 106 patients with primary liver cancer, including 81 with hepatocellular carcinoma and 25 with intrahepatic cholangiocarcinoma. We analyzed the differences between groups in irAE occurrence, including those with and without targeted drugs and those who received interventional therapy. Results: The incidence of irAEs was 39%, with thyroid function, liver function, and skin events being the most common. There was no correlation among irAE incidence and the liver cancer type, stage, or severity; grade of Child-Pugh score; and Barcelona Clinical Liver Cancer classification. However, being overweight was a significant risk factor for irAEs, correlating with high body mass index. The combination of targeted drugs and/or transcatheter arterial chemoembolization therapy did not increase the incidence of irAEs. Conclusion: Being overweight is a potential risk factor for irAEs in primary liver cancer patients. However, there is no correlation between irAE incidence and the liver cancer type, stage, or severity or a combination of targeted drugs or transarterial chemoembolization therapy.

Direct-acting Antiviral-induced Transient Recovery of NK Cells in Early-stage Treatment of Chronic Hepatitis C Patients

BACKGROUND AND AIMS

The rapid clearance of hepatitis C virus induced by direct-acting antivirals (DAAs) affects natural killer (NK) cells, but the reported results are not consistent, and the relative mechanism was unclear. This study focused on the dynamic changes of NK cells during and after DAA treatment and analyzed the reasons.

METHODS

Peripheral blood from 35 chronic hepatitis C patients who were treated with DAAs were collected at baseline and weeks 1, 2, 4, 12, and post-treatment week-12. The frequency, subset, and phenotype of NK cells were assayed by flow cytometry. Lactate dehydrogenase assays were used to evaluate the cytotoxicity of NK cells. Cytokine concentrations were measured with Luminex kits.

RESULTS

All patients achieved a sustained viral response (SVR), and the NK cell frequencies were not changed significantly during DAA therapy. However, the cytotoxicity of NK cells recovered significantly early in week 1, and then continuously decreased below normal levels. The changes of genotypes including NKp30⁺, NKp46⁺, and NKG2A⁺ NK cells were parallel to NK function. The subset of CD56^dim NK cells continuously increased and did not return to normal even at 12 weeks after treatment. Interleukin (IL)-2, IL10, IL15, interferon-gamma, and tumor necrosis factor-alpha all increased after week 4, peaked at the end of therapy, and then exhibited varying degrees of reduction with time.

CONCLUSIONS

DAA treatment led to transient functional recovery of NK cells in the early stage of treatment, and then continuously decreased to below normal levels. Alterations of NK subsets, phenotypes, and the microenvironment may be involved in the changes.

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.

A case report of pulmonary nocardiosis during pembrolizumab: the emerging challenge of the infections on immunotherapy

The increasing occurrence of infectious complications during immune checkpoint inhibitor (ICI) therapy is an emerging challenge for oncologists. ICIs can reverse T-cell exhaustion, and this may lead to hyperinflammatory dysregulated immunity with subsequent potentially fatal infections. Nocardia spp. are opportunistic pathogens belonging to aerobic Actinomycetes. The authors report a case of Nocardia pneumonia in a 62-year-old male with oral squamous cell carcinoma and lung cancer while taking pembrolizumab. The patient did not take corticosteroids or other immunosuppressant medications. Since ICIs are able to stimulate the immune response, the authors hypothesize that immune reconstitution inflammatory syndrome due to pembrolizumab might cause this opportunistic infection.

Natural-Product-Mediated Autophagy in the Treatment of Various Liver Diseases

Autophagy is essential for the maintenance of hepatic homeostasis, and autophagic malfunction has been linked to the pathogenesis of substantial liver diseases. As a popular source of drug discovery, natural products have been used for centuries to effectively prevent the progression of various liver diseases. Emerging evidence has suggested that autophagy regulation is a critical mechanism underlying the therapeutic effects of these natural products. In this review, relevant studies are retrieved from scientific databases published between 2011 and 2022, and a novel scoring system was established to critically evaluate the completeness and scientific significance of the reviewed literature. We observed that numerous natural products were suggested to regulate autophagic flux. Depending on the therapeutic or pathogenic role autophagy plays in different liver diseases, autophagy-regulative natural products exhibit different therapeutic effects. According to our novel scoring system, in a considerable amount of the involved studies, convincing and reasonable evidence to elucidate the regulatory effects and underlying mechanisms of natural-product-mediated autophagy regulation was missing and needed further illustration. We highlight that autophagy-regulative natural products are valuable drug candidates with promising prospects for the treatment of liver diseases and deserve more attention in the future.

Studying Hepatitis Virus-Host Interactions in Patient Liver Biopsies

Infectious diseases are a major contributor to human suffering and the associated socioeconomic burden worldwide. A better understanding of human pathogen-host interactions is a prerequisite for the development of treatment strategies aimed at combatting human pathogen-induced diseases. Model systems that faithfully recapitulate the pathogen-host interactions in humans are critical to gain meaningful insight. Unfortunately, such model systems are not yet available for a number of pathogens. The strict tropism of the hepatitis B (HBV) and C (HCV) viruses for the human liver has made it difficult to study their virus-host interactions during the natural history of these infections. In this case, surplus liver biopsy tissue donated by patients provides an opportunity to obtain a snapshot of the phenomenological and molecular aspects of the human liver of chronically HCV or HBV-infected patients. In this review, we will briefly summarize our own efforts over the years to advance our knowledge of the virus-host interactions during the natural history of chronic HCV and HBV infection.

Programmed Cell Death Protein 1 Axis Inhibition in Viral Infections: Clinical Data and Therapeutic Opportunities

A vital function of the immune system is the modulation of an evolving immune response. It is responsible for guarding against a wide variety of pathogens as well as the establishment of memory responses to some future hostile encounters. Simultaneously, it maintains self-tolerance and minimizes collateral tissue damage at sites of inflammation. In recent years, the regulation of T-cell responses to foreign or self-protein antigens and maintenance of balance between T-cell subsets have been linked to a distinct class of cell surface and extracellular components, the immune checkpoint molecules. The fact that both cancer and viral infections exploit similar, if not the same, immune checkpoint molecules to escape the host immune response highlights the need to study the impact of immune checkpoint blockade on viral infections. More importantly, the process through which immune checkpoint blockade completely changed the way we approach cancer could be the key to decipher the potential role of immunotherapy in the therapeutic algorithm of viral infections. This review focuses on the effect of programmed cell death protein 1/programmed death-ligand 1 blockade on the outcome of viral infections in cancer patients as well as the potential benefit from the incorporation of immune checkpoint inhibitors (ICIs) in treatment of viral infections.

Host Factors in the Natural History of Chronic Hepatitis B: Role of Genetic Determinants

BACKGROUND

The host immune system plays an important role in hepatitis B virus (HBV) infection manifestation. Genetic polymorphisms of several inflammatory cytokines, including TNF-α and IL-10, have been associated with chronic hepatitis B (CHB) progression, although with contradicting results. CHB progression can be categorized into four phases, immune tolerance (IT), immune clearance (IC), low/no replicative (LR), and e-negative hepatitis (ENH), with HBeAg seroconversion as an important milestone. Here, we determined the association of TNF-α (rs1800629) and IL-10 (rs1800896 and rs1800872) SNPs in the context of CHB natural history progression, particularly to HBeAg seroconversion, in Indonesian CHB patients.

METHODS

A total of 287 subjects were recruited and categorized into distinct CHB phases based on HBeAg, viral load, and ALT levels. TNF-α and IL-10 SNPs were determined using PCR-RFLP and confirmed with direct sequencing. The association between SNP genotypes with CHB dynamics was determined using logistic regression presented as odds ratio (OR) with 95% CI.

RESULTS

No significant association was found between IL-10 -592A/C polymorphism and progression of IT and IC to LR, IT and IC to ENH, and LR to ENH phases in all the gene models. IL-10 rs1800896 and TNF-α rs1800629 could not be analyzed using logistic regression. Subjects' age (≥40 years old) was significantly associated with IT and IC to LR (OR: 2.191, 95% CI 1.067-4.578, P = 0.034), IT and IC to ENH (OR: 7.460, 95% CI 3.316-18.310, P < 0.001), and LR to ENH (OR: 5.252, 95% CI 2.010-14.858, P = 0.001). Male gender was associated with LR to ENH (OR: 4.077, 95% CI 1.605-11.023, P = 0.004).

CONCLUSIONS

Age and male gender were associated with CHB phase progression instead of the TNF-α and IL-10 polymorphisms. It would be beneficial to study not only the effect of host determinants but also the viral factor to understand the mechanisms of CHB phase progression.

Hepatitis B virus reactivation in patients undergoing immune checkpoint inhibition: systematic review with meta-analysis

PURPOSE

Immune checkpoint inhibitors (ICIs) have been explored as first-line treatment in various types of previously untreatable malignancies, while limited evidence is available on the management of hepatitis B virus (HBV) in patients undergoing immunotherapy. We systematically reviewed data concerning challenges of hepatic adverse events including HBV reactivation and hepatitis in patients with chronic HBV infection undergoing immunotherapy.

METHODS

A systematic search was conducted in Medline, web of science, Embase and Cochrane library up to May 31, 2022. Studies reporting the safety profile of ICIs in patients with HBV infection were eligible. Meta-analyses were conducted to generate odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

A total of 13 studies including 2561 patients were included for meta-analysis. The overall incidence rates of HBV reactivation in patients with chronic HBV infection and past HBV infection were 1.0% (95% CI 0-3%) and 0% (95% CI 0-0%), respectively. Among patients with chronic HBV infection, the incidence rates of HBV reactivation were 1.0% (95% CI 0-2%) and 10.0% (95% CI 4-18%) for patients with and without antiviral prophylaxis, respectively. Patients with chronic HBV infection were at a higher risk of HBV reactivation compared with those with past HBV infection [OR = 8.69, 95% CI (2.16-34.99)]. Antiviral prophylaxis significantly reduced the risk of HBV reactivation [OR = 0.12, 95% CI (0.02-0.67)] and HBV-associated hepatitis [OR = 0.05, 95% CI (0.01-0.28)] in patients with chronic HBV infection.

CONCLUSIONS

Prophylactic antiviral therapy should be administered to patients with chronic HBV infection undergoing anticancer immunotherapy. Patients with past HBV infection are at lower risk of HBV reactivation compared with those with chronic HBV infection, they could be initiated with antiviral prophylaxis or monitored with the intent of on-demand antiviral therapy.

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

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

The Human Male Liver Is Predisposed to Inflammation Via Enhanced Myeloid Responses to Inflammatory Triggers

Background & Aim

Men have a higher prevalence of liver disease. Liver myeloid cells can regulate tissue inflammation, which drives progression of liver disease. We hypothesized that sex alters the responsiveness of liver myeloid cells, predisposing men to severe liver inflammation.

Methods

Luminex was done on plasma from Hepatitis B Virus infected patients undergoing nucleoside analogue cessation in 45 male and female patients. We collected immune cells from the sinusoids of uninfected livers of 53 male and female donors. Multiparametric flow cytometry was used to phenotype and characterize immune composition. Isolated monocytes were stimulated with TLR ligands to measure the inflammatory potential and the expression of regulators of TLR signaling.

Results

We confirmed that men experienced more frequent and severe liver damage upon Hepatitis B Virus reactivation, which was associated with inflammatory markers of myeloid activation. No differences were observed in the frequency or phenotype of sinusoidal myeloid cells between male and female livers. However, monocytes from male livers produced more inflammatory cytokines and chemokines in response to TLR stimulation than female monocytes. We investigated negative regulators of TLR signaling and found that TOLLIP was elevated in female liver-derived monocytes

Conclusions

Our data show that enhanced responsiveness of myeloid cells from the male liver predisposes men to inflammation, which was associated with altered expression of negative regulators of TLR signaling.

Transarterial Embolization Modulates the Immune Response within Target and Nontarget Hepatocellular Carcinomas in a Rat Model

Background Transarterial embolization (TAE) is the most common treatment for hepatocellular carcinoma (HCC); however, there remain limited data describing the influence of TAE on the tumor immune microenvironment. Purpose To characterize TAE-induced modulation of the tumor immune microenvironment in a rat model of HCC and identify factors that modulate this response. Materials and Methods TAE was performed on autochthonous HCCs induced in rats with use of diethylnitrosamine. CD3, CD4, CD8, and FOXP3 lymphocytes, as well as programmed cell death protein ligand-1 (PD-L1) expression, were examined in three cohorts: tumors from rats that did not undergo embolization (control), embolized tumors (target), and nonembolized tumors from rats that had a different target tumor embolized (nontarget). Differences in immune cell recruitment associated with embolic agent type (tris-acryl gelatin microspheres [TAGM] vs hydrogel embolics) and vascular location were examined in rat and human tissues. A generalized estimating equation model and t, Mann-Whitney U, and χ2 tests were used to compare groups. Results Cirrhosis-induced alterations in CD8, CD4, and CD25/CD4 lymphocytes were partially normalized following TAE (CD8: 38.4%, CD4: 57.6%, and CD25/CD4: 21.1% in embolized liver vs 47.7% [P = .02], 47.0% [P = .01], and 34.9% [P = .03], respectively, in cirrhotic liver [36.1%, 59.6%, and 4.6% in normal liver]). Embolized tumors had a greater number of CD3, CD4, and CD8 tumor-infiltrating lymphocytes relative to controls (191.4 cells/mm2 vs 106.7 cells/mm2 [P = .03]; 127.8 cells/mm2 vs 53.8 cells/mm2 [P < .001]; and 131.4 cells/mm2 vs 78.3 cells/mm2 [P = .01]) as well as a higher PD-L1 expression score (4.1 au vs 1.9 au [P < .001]). A greater number of CD3, CD4, and CD8 lymphocytes were found near TAGM versus hydrogel embolics (4.1 vs 2.0 [P = .003]; 3.7 vs 2.0 [P = .01]; and 2.2 vs 1.1 [P = .03], respectively). The number of lymphocytes adjacent to embolics differed based on vascular location (17.9 extravascular CD68+ peri-TAGM cells vs 7.0 intravascular [P < .001]; 6.4 extravascular CD68+ peri-hydrogel embolic cells vs 3.4 intravascular [P < .001]). Conclusion Transarterial embolization-induced dynamic alterations of the tumor immune microenvironment are influenced by underlying liver disease, embolic agent type, and vascular location. © RSNA, 2022 Online supplemental material is available for this article. See also the editorials by Kennedy et al and by White in this issue.

Risk of Hepatitis B Virus Reactivation in Patients Treated With Immunotherapy for Anti-cancer Treatment

BACKGROUND & AIMS

Hepatitis B virus (HBV) reactivation is a well-known complication in patients with chronic hepatitis B treated with cytotoxic chemotherapy. However, the risk of HBV reactivation through use of immune checkpoint inhibitors (ICIs) is not well understood. Therefore, we aimed to evaluate the risk of HBV reactivation and hepatic adverse events in patients with cancer receiving ICIs according to cancer type and virologic serology.

METHODS

This historical cohort study included 3465 patients with cancer treated with ICIs between January 2015 and September 2020. The primary outcome was the occurrence of HBV reactivation, and the secondary outcome was presence of hepatic adverse events during ICI treatment.

RESULTS

The mean patient age was 62.2 years, and 68.8% of patients were men. Of the 3465 eligible patients, 511 (14.7%) showed hepatitis B surface antigen (HBsAg) positivity. The incidence rates of HBV reactivation of the total patients, HBsAg-positive patients, and HBsAg-negative patients were 0.14% (5/3465), 1.0% (5/511), and 0.0% (0/2954), respectively. Among HBsAg-positive patients, HBV reactivation occurred at a rate of 0.5% (2/409) and 2.9% (3/102) in patients with and without hepatocellular carcinoma, respectively. The HBV reactivation rates were 0.4% (2/464) and 6.4% (3/47) in patients with and without antiviral prophylaxis, respectively. Grade 3-4 hepatitis occurred in 23 (4.5%) HBsAg-positive, and 218 (7.4%) HBsAg-negative patients. No HBV-related fatality occurred. Only 2 patients (0.4%) experienced HBsAg seroclearance after ICI treatment among HBsAg-positive patients.

CONCLUSIONS

In general, HBV reactivation was rarely observed in patients with antiviral prophylaxis while undergoing ICI treatment. However, HBV reactivation may occur in HBsAg-positive patients without antiviral prophylaxis or noncompliant with antiviral prophylaxis.

Improving Therapeutic Vaccination against Hepatitis B-Insights from Preclinical Models of Immune Therapy against Persistent Hepatitis B Virus Infection

Chronic hepatitis B affects more than 250 million individuals worldwide, putting them at risk of developing liver cirrhosis and liver cancer. While antiviral immune responses are key to eliminating hepatitis B virus (HBV) infections, insufficient antiviral immunity characterized by failure to eliminate HBV-infected hepatocytes is associated with chronic hepatitis B. Prophylactic vaccination against hepatitis B successfully established protective immunity against infection with the hepatitis B virus and has been instrumental in controlling hepatitis B. However, prophylactic vaccination schemes have not been successful in mounting protective immunity to eliminate HBV infections in patients with chronic hepatitis B. Here, we discuss the current knowledge on the development and efficacy of therapeutic vaccination strategies against chronic hepatitis B with particular emphasis on the pathogenetic understanding of dysfunctional anti-viral immunity. We explore the development of additional immune stimulation measures within tissues, in particular activation of immunogenic myeloid cell populations, and their use for combination with therapeutic vaccination strategies to improve the efficacy of therapeutic vaccination against chronic hepatitis B.

In Vivo Bioluminescence Imaging of HBV Replicating Hepatocytes Allows for the Monitoring of Anti-Viral Immunity

Immunity against hepatitis B virus (HBV) infection is complex and not entirely understood so far, including the decisive factors leading to the development of chronic hepatitis B. This lack of a mechanistic understanding of HBV-specific immunity is also caused by a limited number of suitable animal models. Here, we describe the generation of a recombinant adenovirus expressing an HBV 1.3-overlength genome linked to luciferase (Ad-HBV-Luc) allowing for precise analysis of the quantity of infected hepatocytes. This enables sensitive and close-meshed monitoring of HBV-specific CD8 T cells and the onset of anti-viral immunity in mice. A high dose of Ad-HBV-Luc developed into chronic hepatitis B accompanied by dysfunctional CD8 T cells characterized by high expression of PD1 and TOX and low expression of KLRG1 and GzmB. In contrast, a low dose of Ad-HBV-Luc infection resulted in acute hepatitis with CD8 T cell-mediated elimination of HBV-replicating hepatocytes associated with elevated sALT levels and increased numbers of cytotoxic HBV-specific CD8 T cells. Thus, the infectious dose was a critical factor to induce either acute self-limited or chronic HBV infection in mice. Taken together, the new Ad-HBV-Luc vector will allow for highly sensitive and time-resolved analysis of HBV-specific immune responses during acute and chronic infection.

Virological breakthrough after immune checkpoint inhibitor and nucleos(t)ide analog treatment in patients with hepatitis B surface antigen positive hepatocellular carcinoma: a real-world study

Background

Immune checkpoint inhibitors (ICIs) have been shown to be a promising and effective treatment for hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). However, there is a lack of evidence-based data demonstrating the impact of ICIs on HBV DNA level in HBV-HCC patients undergoing nucleos(t)ide analog (NA) therapy and of HBV DNA variation on patient survival. In this study, we aimed to investigate this issue in the real world.

Methods

In this single-center retrospective study, we reviewed 182 baseline hepatitis B surface antigen (HBsAg)-positive HBV-HCC patients who were treated with ICIs and pre-emptive NAs. The demographic characteristics, tumor status, treatments, HBV DNA, HBsAg, liver function, antitumor response, and patient survival were investigated. The primary endpoints were the virological breakthrough (VB) rate, HBV reactivation (HBVr) rate, and long-term HBV DNA control; the secondary endpoints were the overall survival (OS) and progression-free survival (PFS).

Results

(1) VB and HBVr occurred in 18.1% (33/182) and 4.4% (8/182) of patients with a median occurrence time of 3.9 months (range, 0.7–16.0) and 8.0 months (range, 3.0–16.0), respectively. The HBV DNA negative rates were 26.1% and 0 at 24 and 48 weeks in the VB group and 12.5% and 0 in the HBVr group, respectively. A baseline HBsAg level ≥200 IU/mL was the only risk factor for VB (OR 9.9, 95% CI 2.2 to 45.2, p=0.003); (2) patients with VB had much shorter median OS and median PFS than those without (12.3 months vs 18.1 months, p=0.035; 4.5 months vs 7.5 months, p=0.011).

Conclusions

There was a high risk of VB and a moderate risk of HBVr in HBsAg-positive HBV-HCC patients (with poor long-term HBV DNA control) undergoing ICI and pre-emptive NA therapies. The only risk factor for VB was the pretreatment HBsAg level. Further, VB might be considered as a clinical biomarker predicting inferior OS and PFS in the patients.

Infections due to dysregulated immunity: an emerging complication of cancer immunotherapy

Immune checkpoint inhibitors (ICIs) have revolutionised cancer treatment. However, immune-related adverse events (irAEs) are a common side effect which can mimic infection. Additionally, treatment of irAEs with corticosteroids and other immunosuppressant agents can lead to opportunistic infection, which we have classed as immunotherapy infections due to immunosuppression. However, emerging reports demonstrate that some infections can be precipitated by ICIs in the absence of immunosuppressive treatment, in contrast to the majority of reported cases. These infections are characterised by a dysregulated inflammatory immune response, and so we propose they are described as immunotherapy infections due to dysregulated immunity. This review summarises the rapidly emerging evidence of these phenomena and proposes a new framework for considering infection in the context of cancer immunotherapy.

Delivery of toll-like receptor 3 ligand poly(I:C) to the liver by calcium phosphate nanoparticles conjugated with an F4/80 antibody exerts an anti-hepatitis B virus effect in a mouse model

Hepatitis B virus (HBV) is a global health issue, but currently available anti-HBV drugs have limited success. Previously, introduction of the Toll-like receptor (TLR)-3 ligand poly(I:C) to the liver via hydrodynamic injection (HI) was shown to effectively suppress HBV replication in a chronic HBV replication mouse model. However, this method cannot be applied in human beings. To improve the liver targeting of poly(I:C) via intravenous injection, calcium phosphate nanoparticles (CPNs) carrying poly(I:C) with or without antibodies were constructed, and their anti-HBV effects were investigated. We found that significantly more anti-F4/80-conjugated and IgG2α-conjugated nanoparticles were taken up in liver cells both in vivo and in vitro. In addition, these nanoparticles produced pronounced immunostimulatory effects in vitro in primary liver cells. Importantly, treatment with nanoparticles carrying poly(I:C) increased the production of intrahepatic cytokines and chemokines and enhanced T cell responses, significantly reducing HBsAg, HBeAg and HBV DNA levels in the mice. Compared to nonconjugated and isotype-antibody-conjugated nanoparticles, the anti-F4/80-conjugated nanoparticles demonstrated the strongest anti-HBV effects. In summary, nanoparticles carrying poly(I:C) conjugated with an F4/80 antibody promoted liver targeting, and they may represent a suitable alternative to HI for future anti-HBV treatment. STATEMENT OF SIGNIFICANCE: HBV chronically infects approximately 250 million individuals worldwide but current anti-HBV drugs have limited success. Introduction of toll-like receptor 3 ligand poly(I:C) into liver by hydrodynamic injection has been proven to promote HBV clearance in mouse model. However, this technique is not clinically suitable for human patients. We have constructed calcium phosphate nanoparticles carrying poly(I:C) with specific antibody targeting liver nonparenchymal cells. The uptake into relevant liver cells and the anti-HBV effects were studied. After intravenous injection into mice, the uptake rate of anti-F4/80-conjugated nanoparticels was enhanced in liver, and these nanoparticles exert effective anti-HBV effects in vivo. This may provide important insight into future HBV immunotherapy based on nanoparticle-mediated drug delivery.

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.

Interferon and Hepatitis B: Current and Future Perspectives

Chronic hepatitis B virus (HBV) infection remains a major health burden worldwide for which there is still no effective curative treatment. Interferon (IFN) consists of a group of cytokines with antiviral activity and immunoregulatory and antitumor effects, that play crucial roles in both innate and adaptive immune responses. IFN-α and its pegylated form have been used for over thirty years to treat chronic hepatitis B (CHB) with advantages of finite treatment duration and sustained virologic response, however, the efficacy is limited and side effects are common. Here, we summarize the status and unique advantages of IFN therapy against CHB, review the mechanisms of IFN-α action and factors affecting IFN response, and discuss the possible improvement of IFN-based therapy and the rationale of combinations with other antiviral agents in seeking an HBV cure.

The immunological and metabolic landscape in primary and metastatic liver cancer

The liver is the sixth most common site of primary cancer in humans, and generally arises in a background of cirrhosis and inflammation. Moreover, the liver is frequently colonized by metastases from cancers of other organs (particularly the colon) because of its anatomical location and organization, as well as its unique metabolic and immunosuppressive environment. In this Review, we discuss how the hepatic microenvironment adapts to pathologies characterized by chronic inflammation and metabolic alterations. We illustrate how these immunological or metabolic changes alter immunosurveillance and thus hinder or promote the development of primary liver cancer. In addition, we describe how inflammatory and metabolic niches affect the spreading of cancer metastases into or within the liver. Finally, we review the current therapeutic options in this context and the resulting challenges that must be surmounted.

HBV-Specific CD8+ T-Cell Tolerance in the Liver

Hepatitis B virus (HBV) remains a leading cause of liver-related morbidity and mortality through chronic hepatitis that may progress to liver cirrhosis and cancer. The central role played by HBV-specific CD8+ T cells in the clearance of acute HBV infection, and HBV-related liver injury is now well established. Vigorous, multifunctional CD8+ T cell responses are usually induced in most adult-onset HBV infections, while chronic hepatitis B (CHB) is characterized by quantitatively and qualitatively weak HBV-specific CD8+ T cell responses. The molecular basis of this dichotomy is poorly understood. Genomic analysis of dysfunctional HBV-specific CD8+ T cells in CHB patients and various mouse models suggest that multifaceted mechanisms including negative signaling and metabolic abnormalities cooperatively establish CD8+ T cell dysfunction. Immunoregulatory cell populations in the liver, including liver resident dendritic cells (DCs), hepatic stellate cells (HSCs), myeloid-derived suppressor cells (MDSCs), may contribute to intrahepatic CD8+ T cell dysfunction through the production of soluble mediators, such as arginase, indoleamine 2,3-dioxygenase (IDO) and suppressive cytokines and the expression of co-inhibitory molecules. A series of recent studies with mouse models of HBV infection suggest that genetic and epigenetic changes in dysfunctional CD8+ T cells are the manifestation of prolonged antigenic stimulation, as well as the absence of co-stimulatory or cytokine signaling. These new findings may provide potential new targets for immunotherapy aiming at invigorating HBV-specific CD8+ T cells, which hopefully cures CHB.

Advances in treatment and prevention of hepatitis B

Chronic hepatitis B (CHB) continues to contribute to worldwide morbidity and mortality significantly. Scientists, clinicians, pharmaceutical companies, and health organizations have dedicated substantial Intellectual and monetary resources to finding a cure, increasing immunization rates, and reducing the global burden of CHB. National and international health-related organizations including the center for disease control, the national institute of health, the American Association for the study of liver disease (AASLD), The European association for the study of the Liver (EASL), The Asia Pacific association for the study of the Liver (APASL) and the world health organization release periodic recommendations for disease prevention and treatment. Our review of the most recent guidelines by EASL, AASLD, APASL, and Taiwan Association for the Study of the Liver revealed that an overwhelming majority of cited studies were published before 2018. We reviewed Hepatitis B-related literature published 2018 onwards to identify recent developments and current barriers that will likely direct future efforts towards eradicating hepatitis B. The breakthrough in our understanding of the hepatitis B virus life cycle and resulting drug development is encouraging with significant room for further progress. Data from high-risk populations, most vulnerable to the devastating effects of hepatitis B infection and reactivation remain sparse. Utilization of systems approach, optimization of experimental models, identification and validation of next-generation biomarkers, and precise modulation of the human immune response will be critical for future innovation. Within the foreseeable future, new treatments will likely complement conventional therapies rather than replace them. Most Importantly, pragmatic management of CHB related population health challenges must be prioritized to produce real-world results.

Integrative microphysiological tissue systems of cancer metastasis to the liver

The liver is the most commonly involved organ in metastases from a wide variety of solid tumors. The use of biologically and cellularly complex liver tissue systems have shown that tumor cell behavior and therapeutic responses are modulated within the liver microenvironment and in ways distinct from the behaviors in the primary locations. These microphysiological systems have provided unexpected and powerful insights into the tumor cell biology of metastasis. However, neither the tumor nor the liver exist in an isolated tissue situation, having to function within a complete body and respond to systemic events as well as those in other organs. To examine the influence of one organ on the function of other tissues, microphysiological systems are being linked. Herein, we discuss extending this concept to tumor metastases by integrating complex models of the primary tumor with the liver metastatic environment. In addition, inflammatory organs and the immune system can be incorporated into these multi-organ systems to probe the effects on tumor behavior and cancer treatments.

T cell receptor repertoires within liver allografts are different to those in the peripheral blood

BACKGROUND & AIMS

T cells are the main mediators of allogeneic immune responses. Specific T cell clones can be tracked by their unique T cell receptor (TCR), but specificity and function remain elusive and have not been investigated in human liver biopsies thus far.

METHODS

TCR repertoire analysis of CD4⁺, CD8⁺, and regulatory T cells of the peripheral blood and liver graft was performed in 7 liver transplant recipients with either stable course (non-rejector, NR), subclinical cellular rejection (SCR), or acute cellular rejection (ACR) during an observation period from pre-transplant to 6 years post-transplant. Furthermore, donor-reactive T cells, identified by their expression of CD154 and glycoprotein A repetitions predominant (GARP) after allogeneic activation, were tracked longitudinally in peripheral blood and within the liver allograft.

RESULTS

Although overall clonality of the TCR repertoire did not increase in peripheral blood after liver transplantation, clonality of donor-reactive CD4⁺ and regulatory T cells increased and these clones accumulated within the liver graft. Surprisingly, the TCR repertoires between the liver graft and the periphery were distinct and showed only limited overlap. Notably, during ACR, TCR repertoires aligned suggesting either graft-specific homing or release of activated T cells from the graft.

CONCLUSIONS

This is the first study comparing TCR repertoires between liver grafts and blood in patients with NR, SCR, and ACR. Moreover, we attribute specificity and function to a subgroup of intragraft T cell populations. Given the limited overlap between peripheral blood and intragraft repertoires, future studies investigating function and specificities of T cells after liver transplantation should focus on the intragraft immune response.

LAY SUMMARY

In solid organ transplantation, T cells are key mediators of the recipient's immune response directed at the transplanted organ. In our study, we characterised the T cell repertoire in a cohort of 7 liver transplant recipients. We demonstrate that donor-specific T cells expand clonally and accumulate in the transplanted liver. Moreover, we show that the composition of T cells in peripheral blood differs from the T cells in the liver allograft, only aligning in the context of acute cellular rejection but not in normal graft or subclinical cellular rejection. This indicates that the intragraft immune response is not mirrored in the peripheral blood. Our findings clarify the importance of protocol liver biopsies in identifying intragraft immune responses for future investigations of allo-directed immune responses.

Combination Immunotherapy for Hepatocellular Carcinoma: Where Are We Currently?

The past decade has seen a rise in the availability of breakthrough therapeutic strategies for treatment of hepatocellular carcinoma (HCC). A tumor microenvironment in HCC is regulated by various immunotolerance mechanisms; therefore, therapeutic strategies aiming at disrupting tumor immune tolerance are becoming attractive curative options in HCC. Immune checkpoint inhibitors have demonstrated impressive effectiveness in HCC, including in sorafenib-unresponsive patients. Synergistic approaches with checkpoint inhibitors (anti-PD-1/PD-L1 and CTLA-4) and antiangiogenic drugs are burgeoning as first-line treatment therapeutic modalities in HCC.

Recent Advances and Future Prospects in Immune Checkpoint (ICI)-Based Combination Therapy for Advanced HCC

Advanced, unresectable hepatocellular carcinoma has a dismal outcome. Multiple immune checkpoint inhibitors (ICIs) targeting the programmed-cell death 1 pathway (PD-1/L1) have been approved for the treatment of advanced HCC. However, outcomes remain undesirable and unpredictable on a patient-to-patient basis. The combination of anti-PD-1/L1 with alternative agents, chiefly cytotoxic T-lymphocyte antigen-4 (CTLA-4) ICIs or agents targeting other oncogenic pathways such as the vascular endothelial growth factor (VEGF) pathway and the c-MET pathway, has, in addition to the benefit of directly targeting alterative oncogenic pathways, in vitro evidence of synergism through altering the genomic and function signatures of T cells and expression of immune checkpoints. Several trials have been completed or are underway evaluating such combinations. Finally, studies utilizing transcriptomics and organoids are underway to establish biomarkers to predict ICI response. This review aims to discuss the biological rationale and clinical advances in ICI-based combinations in HCCs, as well as the progress and prospects of the search for the aforementioned biomarkers in ICI treatment of HCC.

Comparison of HBV reactivation between patients with high HBV-DNA and low HBV-DNA loads undergoing PD-1 inhibitor and concurrent antiviral prophylaxis

BACKGROUND

Programmed cell death protein-1 (PD-1) inhibitor is recommended to treat advanced hepatocellular carcinoma (HCC). However, the safety of PD-1 inhibitor in patients with high HBV-DNA load is unknown because of the potential risk of hepatitis B virus (HBV) reactivation. This study was to compare the HBV reactivation between patients with low HBV-DNA loads and high HBV-DNA loads undergoing antiviral prophylaxis and PD-1 inhibitor.

METHODS

This was a retrospective study including consecutive hepatitis B surface antigen-positive HCC patients who received PD-1 inhibitor and concurrent antiviral prophylaxis for prevention of clinical hepatitis. Patients were divided into low HBV-DNA group (low group, ≤ 500 IU/ml) and high HBV-DNA group (high group, > 500 IU/ml) according to the baseline HBV-DNA level. The incidences of HBV reactivation, HBV-associated hepatitis, and PD-1 inhibitor disruption were compared between the two groups.

RESULTS

Two hundred two eligible patients were included: 94 in the low group and 108 in the high group. Seven patients (5 in the low group and 2 in the high group) developed HBV reactivation, and all recovered from HBV reactivation and HBV-associated hepatitis. The incidence of HBV reactivation in the two groups was low (5.3% vs 1.9%, P = 0.34). There was also no difference in the incidence of HBV-associated hepatitis (P = 0.56), or PD-1 inhibitor disruption (P = 0.82). The multivariable analysis showed PD-1 inhibitor with hepatic arterial infusion chemotherapy was the only significant risk factor for HBV reactivation (P = 0.04) and hepatitis (P = 0.002).

CONCLUSION

With concurrent antiviral prophylaxis, HBV-DNA load higher than 500 IU/ml should not be a contraindication for PD-1 inhibitor.

HBV-Integration Studies in the Clinic: Role in the Natural History of Infection

Hepatitis B virus (HBV) infection is a major global health problem causing acute and chronic liver disease that can lead to liver cirrhosis and hepatocellular carcinoma (HCC). HBV covalently closed circular DNA (cccDNA) is essential for viral replication and the establishment of a persistent infection. Integrated HBV DNA represents another stable form of viral DNA regularly observed in the livers of infected patients. HBV DNA integration into the host genome occurs early after HBV infection. It is a common occurrence during the HBV life cycle, and it has been detected in all the phases of chronic infection. HBV DNA integration has long been considered to be the main contributor to liver tumorigenesis. The recent development of highly sensitive detection methods and research models has led to the clarification of some molecular and pathogenic aspects of HBV integration. Though HBV integration does not lead to replication-competent transcripts, it can act as a stable source of viral RNA and proteins, which may contribute in determining HBV-specific T-cell exhaustion and favoring virus persistence. The relationship between HBV DNA integration and the immune response in the liver microenvironment might be closely related to the development and progression of HBV-related diseases. While many new antiviral agents aimed at cccDNA elimination or silencing have been developed, integrated HBV DNA remains a difficult therapeutic challenge.

Translation of IRF-1 Restricts Hepatic Interleukin-7 Production to Types I and II Interferons: Implications for Hepatic Immunity

Interleukin-7 (IL-7) is an important cytokine with pivotal pro-survival functions in the adaptive immune system. However, the role of IL-7 in innate immunity is not fully understood. In the present study, the impact of hepatic IL-7 on innate immune cells was assessed by functional experiments as well as in patients with different stages of liver cirrhosis or acute-on-chronic liver failure (ACLF). Human hepatocytes and liver sinusoidal endothelial cells secreted IL-7 in response to stimulation with interferons (IFNs) of type I and II, yet not type III. De novo translation of interferon-response factor-1 (IRF-1) restricted IL-7 production to stimulation with type I and II IFNs. LPS-primed human macrophages were identified as innate immune target cells responding to IL-7 signaling by inactivation of Glycogen synthase kinase-3 (GSK3). IL-7-mediated GSK3 inactivation augmented LPS-induced secretion of pro-inflammatory cytokines and blunted LPS tolerance of macrophages. The IFN-IRF-1-IL-7 axis was present in liver cirrhosis patients. However, liver cirrhosis patients with or without ACLF had significantly lower concentrations of IL-7 in serum compared to healthy controls, which might contribute to LPS-tolerance in these patients. In conclusion, we propose the presence of an inflammatory cascade where IFNs of type I/II induce hepatocellular IL-7 in an IRF-1-restriced way. Beyond its role in adaptive immune responses, IL-7 appears to augment the response of macrophages to LPS and to ameliorate LPS tolerance, which may improve innate immune responses against invading pathogens.

T cell immunity to hepatitis C virus: Lessons for a prophylactic vaccine

There is consensus that HCV-specific T cells play a central role in the outcome (clearance vs. persistence) of acute infection and that they contribute to protection against the establishment of persistence after reinfection. However, these T cells often fail and the virus can persist, largely as a result of T cell exhaustion and the emergence of viral escape mutations. Importantly, HCV cure by direct-acting antivirals does not lead to a complete reversion of T cell exhaustion and thus HCV reinfections can occur. The current lack of detailed knowledge about the immunological determinants of viral clearance, persistence and protective immunity is a major roadblock to the development of a prophylactic T cell vaccine. This minireview highlights the basic concepts of successful T cell immunity, major mechanisms of T cell failure and how our understanding of these concepts can be translated into a prophylactic vaccine.

PD-1 silencing improves anti-tumor activities of human mesothelin-targeted CAR T cells

Chimeric antigen receptor T (CAR T) cell therapy is a new pillar in cancer therapeutics, and has been successfully used for the treatment of cancers, including acute lymphoblastic leukemia and solid cancers. Following immune attack, many tumors upregulate inhibitory ligands which bind to inhibitory receptors on T cells. For example, the interaction between programmed cell death protein 1 (PD-1) on activated T cells and its ligands (widely known as PD-L1) on a target tumor limits the efficacy of CAR T cells therapy against poorly responding tumors. Here, we use mesothelin (MSLN)-expressing human ovarian cancer cells (SKOV3) and human colon cancer cells (HCT116) to investigate whether PD-1-mediated T cell exhaustion affects the anti-tumor activity of MSLN-targeted CAR T cells. We utilized cell-intrinsic PD-1-targeting shRNA overexpression strategy, resulting in a significant PD-1 silencing in CAR T cells. The reduction of PD-1 expression on T cell surface strongly augmented CAR T cell cytokine production and cytotoxicity towards PD-L1-expressing cancer cells in vitro. This study indicates the enhanced anti-tumor efficacy of PD-1-silencing MSLN-targeted CAR T cells against several cancers and suggests the potential of other specific gene silencing on the immune checkpoints to enhance the CAR T cell therapies against human tumors.

Reduced mitochondrial resilience enables non-canonical induction of apoptosis after TNF receptor signaling in virus-infected hepatocytes

BACKGROUND & AIMS

Selective elimination of virus-infected hepatocytes occurs through virus-specific CD8 T cells recognizing peptide-loaded MHC molecules. Herein, we report that virus-infected hepatocytes are also selectively eliminated through a cell-autonomous mechanism.

METHODS

We generated recombinant adenoviruses and genetically modified mouse models to identify the molecular mechanisms determining TNF-induced hepatocyte apoptosis in vivo and used in vivo bioluminescence imaging, immunohistochemistry, immunoblot analysis, RNAseq/proteome/phosphoproteome analyses, bioinformatic analyses, mitochondrial function tests.

RESULTS

We found that TNF precisely eliminated only virus-infected hepatocytes independently of local inflammation and activation of immune sensory receptors. TNF receptor I was equally relevant for NF-kB activation in healthy and infected hepatocytes, but selectively mediated apoptosis in infected hepatocytes. Caspase 8 activation downstream of TNF receptor signaling was dispensable for apoptosis in virus-infected hepatocytes, indicating an unknown non-canonical cell-intrinsic pathway promoting apoptosis in hepatocytes. We identified a unique state of mitochondrial vulnerability in virus-infected hepatocytes as the cause for this non-canonical induction of apoptosis through TNF. Mitochondria from virus-infected hepatocytes showed normal biophysical and bioenergetic functions but were characterized by reduced resilience to calcium challenge. In the presence of unchanged TNF-induced signaling, reactive oxygen species-mediated calcium release from the endoplasmic reticulum caused mitochondrial permeability transition and apoptosis, which identified a link between extrinsic death receptor signaling and cell-intrinsic mitochondrial-mediated caspase activation.

CONCLUSION

Our findings reveal a novel concept in immune surveillance by identifying a cell-autonomous defense mechanism that selectively eliminates virus-infected hepatocytes through mitochondrial permeability transition.

LAY SUMMARY

The liver is known for its unique immune functions. Herein, we identify a novel mechanism by which virus-infected hepatocytes can selectively eliminate themselves through reduced mitochondrial resilience to calcium challenge.

Investigational drugs with dual activity against HBV and HIV (Review)

Chronic hepatitis B (CHB) and acquired immunodeficiency syndrome (AIDS) are global public health problems that pose a significant health burden. Human immunodeficiency virus (HIV) and hepatitis B virus (HBV) coinfection is common, as these viruses have similar transmission routes, such as blood transmission, sexual transmission and mother-to-child transmission. Coinfection frequently leads to accelerated disease progression. For individuals coinfected with HIV/HBV, combination antiretroviral therapy containing dual anti-HBV drugs is recommended. Certain studies have also indicated the benefits of antiretroviral drugs with anti-HBV activity in patients with coinfection. A total of four Food and Drug Administration-approved HIV drugs also have anti-HBV activity; namely, emtricitabine, lamivudine, tenofovir disoproxil fumarate and tenofovir alafenamide, which are all nucleoside reverse transcriptase inhibitors. However, various issues, including drug resistance and side effects, limit their application. Therefore, it is necessary to develop more drugs with dual activity against HBV and HIV. The present review outlines the mechanisms, safety and efficacy of certain drugs that have been investigated for this purpose.

Modulation of the liver immune microenvironment by the adeno-associated virus serotype 8 gene therapy vector

Adeno-associated viruses (AAVs) are emerging as one of the vehicles of choice for gene therapy. However, the potential immunogenicity of these vectors is a major limitation of their use, leading to the necessity of a better understanding of how viral vectors engage the innate immune system. In this study, we demonstrate the immune response mediated by an AAV vector in a mouse model. Mice were infected intravenously with 4 × 10¹² copies (cp)/kg of AAV8, and the ensuing immune response was analyzed using intravital microscopy during a period of weeks. Administration of AAV8 resulted in the infection of hepatocytes, and this infection led to a moderate, but significant, activation of the immune system in the liver. This host immune response involved platelet aggregation, neutrophil extracellular trap (NET) formation, and the recruitment of monocytes, B cells, and T cells. The resident liver macrophage population, Kupffer cells, was necessary to initiate this immune response, as its depletion abrogated platelet aggregation and NET formation and delayed the recruitment of immune cells. Moreover, the death of liver cells produced by this AAV was moderate and failed to result in a robust, sustained inflammatory response. Altogether, these data suggest that AAV8 is a suitable vector for gene therapy approaches.

Characterizing Hepatitis C Virus-Specific CD4+ T Cells Following Viral-Vectored Vaccination, Directly Acting Antivirals, and Spontaneous Viral Cure

BACKGROUND AND AIMS

Induction of functional helper CD4⁺ T cells is the hallmark of a protective immune response against hepatitis C virus (HCV), associated with spontaneous viral clearance. Heterologous prime/boost viral vectored vaccination has demonstrated induction of broad and polyfunctional HCV-specific CD8⁺ T cells in healthy volunteers; however, much less is known about CD4⁺ T-cell subsets following vaccination.

APPROACH AND RESULTS

We analyzed HCV-specific CD4⁺ T-cell populations using major histocompatibility complex class II tetramers in volunteers undergoing HCV vaccination with recombinant HCV adenoviral/modified vaccinia Ankara viral vectors. Peptide-specific T-cell responses were tracked over time, and functional (proliferation and cytokine secretion) and phenotypic (cell surface and intranuclear) markers were assessed using flow cytometry. These were compared to CD4⁺ responses in 10 human leukocyte antigen-matched persons with HCV spontaneous resolution and 21 chronically infected patients treated with directly acting antiviral (DAA) therapy. Vaccination induced tetramer-positive CD4⁺ T cells that were highest 1-4 weeks after boosting (mean, 0.06%). Similar frequencies were obtained for those tracked following spontaneous resolution of disease (mean, 0.04%). In addition, the cell-surface phenotype (CD28, CD127) memory subset markers and intranuclear transcription factors, as well as functional capacity of peptide-specific CD4⁺ T-cell responses characterized after vaccination, are comparable to those following spontaneous viral resolution. In contrast, helper responses in chronic infection were infrequently detected and poorly functional and did not consistently recover following HCV cure.

CONCLUSIONS

Helper CD4⁺ T-cell phenotype and function following HCV viral vectored vaccination resembles "protective memory" that is observed following spontaneous clearance of HCV. DAA cure does not promote resurrection of exhausted CD4⁺ T-cell memory in chronic infection.