Pathogenesis of chronic viral hepatitis: differential roles of T cells and NK cells

Molecular epidemiology of hepatitis B virus (HBV) in Ethiopia: A review article

Hepatitis B virus (HBV) belongs to the family Hepadnaviridae and is the smallest human DNA virus, with a genome that is only 3200 nucleotides long. The absence of proofreading function in HBV reverse transcriptase provides a wide range of genetic variants for targeted outgrowth at different stages of infection. A number of sub genotypes and ten HBV genotypes (A through J) have been identified through analyses of the divergence of HBV genomic sequences. Numerous clinical outcomes, including the emergence of chronicity, the course of the disease, the effectiveness of treatment, and the response to vaccination, have been related to differences in genotype between HBV isolates. There are just seven studies that have been done in Ethiopia that examine the molecular epidemiology of HBV. Moreover, these studies haven't been compiled and reviewed yet. In this review, we looked at the genetic diversity and molecular epidemiology of HBV, the relationship between HBV genotypes and clinical outcomes, the immunopathogenesis of HBV, and finally the molecular epidemiology of HBV in Ethiopia. PubMed, Embase, and Google Scholar search engines were used to find relevant articles for the review. By using HBV genotyping, clinicians can better tailor vaccination decisions and antiviral therapy for patients with chronic hepatitis B who are more likely to experience the disease's progression.

Differential methylation patterns in paternally imprinted gene promoter regions in sperm from hepatitis B virus infected individuals

BACKGROUND

Hepatitis B virus (HBV) infection poses a substantial threat to human health, impacting not only infected individuals but also potentially exerting adverse effects on the health of their offspring. The underlying mechanisms driving this phenomenon remain elusive. This study aims to shed light on this issue by examining alterations in paternally imprinted genes within sperm.

METHODS

A cohort of 35 individuals with normal semen analysis, comprising 17 hepatitis B surface antigen (HBsAg)-positive and 18 negative individuals, was recruited. Based on the previous research and the Online Mendelian Inheritance in Man database (OMIM, https://www.omim.org/ ), targeted promoter methylation sequencing was employed to investigate 28 paternally imprinted genes associated with various diseases.

RESULTS

Bioinformatic analyses revealed 42 differentially methylated sites across 29 CpG islands within 19 genes and four differentially methylated CpG islands within four genes. At the gene level, an increase in methylation of DNMT1 and a decrease in methylation of CUL7, PRKAG2, and TP53 were observed. DNA methylation haplotype analysis identified 51 differentially methylated haplotypes within 36 CpG islands across 22 genes.

CONCLUSIONS

This is the first study to explore the effects of HBV infection on sperm DNA methylation and the potential underlying mechanisms of intergenerational influence of paternal HBV infection.

Risk of hepatic decompensation from hepatitis B virus reactivation in hematological malignancy treatments

In this editorial, we discussed the apparent discrepancy between the findings described by Colapietro et al, in their case report and data found in the literature. Colapietro et al reported a case of hepatitis B virus (HBV)-related hepatic decompensation in a patient with chronic myeloid leukemia and a previously resolved HBV infection who was receiving Bruton's tyrosine kinase (BTK) inhibitor therapy. First of all, we recapitulated the main aspects of the immune system involved in the response to HBV infection in order to underline the role of the innate and adaptive response, focusing our attention on the protective role of anti-HBs. We then carefully analyzed literature data on the risk of HBV reactivation (HBVr) in patients with previous HBV infection who were treated with either tyrosine kinase inhibitors or BTK inhibitors for their hematologic malignancies. Based on literature data, we suggested that several factors may contribute to the different risks of HBVr: The type of hematologic malignancy; the type of therapy (BTK inhibitors, especially second-generation, seem to be at a higher risk of HBVr than those with tyrosine kinase inhibitors); previous exposure to an anti-CD20 as first-line therapy; and ethnicity and HBV genotype. Therefore, the warning regarding HBVr in the specific setting of patients with hematologic malignancies requires further investigation.

Imprinted immune abnormalities in liver transplant patients cured of hepatitis C with antiviral drugs

Chronic HCV infection induces interferon and dysregulates immune responses through inflammation and chronic antigenic stimulation. Antiviral drugs can cure HCV, providing a unique opportunity to examine the immunological restoration that does and does not occur when a chronic viral infection is eradicated. We quantified blood cytokines levels and used mass cytometry to immunophenotype peripheral blood mononuclear cells before and after HCV cure in 2 groups of patients and controls. At baseline, serum interferon α and soluble CD163 (a macrophage product) were elevated in both liver transplant and nonliver transplant patients compared to controls; the frequencies of several peripheral blood mononuclear cell populations differed from controls; and programmed death protein 1-positivity was increased in nearly all T cell subsets. Many abnormalities persisted after HCV cure, including elevated programmed death protein 1 expression on CD4 naïve and central memory T cells, elevated soluble CD163, and expansion of the plasmablast/plasma cell compartment. Several myeloid-lineage subsets, including Ag-presenting dendritic cells, remained dysregulated. In mechanistic studies, interferon α treatment increased programmed death protein 1 on human T cells and increased T cell receptor signaling. The data identify immunological abnormalities that persist after curative HCV treatment. Before cure, high levels of interferon α may stimulate programmed death protein 1 expression on human T cells, causing persistent functional changes.

Impending HCC diagnosis in patients with cirrhosis after HCV cure features a natural killer cell signature

BACKGROUND AND AIMS

The risk of developing HCC in chronically infected patients with AQ2 HCV with liver cirrhosis is significantly elevated. This risk remains high even after a sustained virological response with direct-acting antivirals. To date, disease-associated signatures of NK cells indicating HCC development are unclear.

APPROACH AND RESULTS

This study investigated NK cell signatures and functions in 8 cohorts covering the time span of HCC development, diagnosis, and onset. In-depth analysis of NK cell profiles from patients with cirrhosis who developed HCC (HCV-HCC) after sustained virological response compared with those who remained tumor-free (HCV-noHCC) revealed increasingly dissimilar NK cell signatures over time. We identified expression patterns with persistently high frequencies of TIM-3 and CD38 on NK cells that were largely absent in healthy controls and were associated with a high probability of HCC development. Functional assays revealed that the NK cells had potent cytotoxic features. In contrast to HCV-HCC, the signature of HCV-noHCC converged with the signature found in healthy controls over time. Regarding tissue distribution, single-cell sequencing showed high frequencies of these cells in liver tissue and the invasive margin but markedly lower frequencies in tumors.

CONCLUSIONS

We show that HCV-related HCC development has profound effects on the imprint of NK cells. Persistent co-expression of TIM-3hi and CD38 + on NK cells is an early indicator for HCV-related HCC development. We propose that the profiling of NK cells may be a rapid and valuable tool to assess the risk of HCC development in a timely manner in patients with cirrhosis after HCV cure.

Epigenetic scars in regulatory T cells are retained after successful treatment of chronic hepatitis C with direct-acting antivirals

BACKGROUND & AIMS

Chronic HCV infection results in abnormal immunological alterations, which are not fully normalized after viral elimination by direct-acting antiviral (DAA) treatment. Herein, we longitudinally examined phenotypic, transcriptomic, and epigenetic alterations in peripheral blood regulatory T (Treg) cells from patients with chronic HCV infection before, during, and after DAA treatment.

METHODS

Patients with chronic genotype 1b HCV infection who achieved sustained virologic response by DAA treatment and age-matched healthy donors were recruited. Phenotypic characteristics of Treg cells were investigated through flow cytometry analysis. Moreover, the transcriptomic and epigenetic landscapes of Treg cells were analyzed using RNA sequencing and ATAC-seq (assay for transposase-accessible chromatin with sequencing) analysis.

RESULTS

The Treg cell population - especially the activated Treg cell subpopulation - was expanded in peripheral blood during chronic HCV infection, and this expansion was sustained even after viral clearance. RNA sequencing analysis revealed that viral clearance did not abrogate the inflammatory features of these Treg cells, such as Treg activation and TNF signaling. Moreover, ATAC-seq analysis showed inflammatory imprinting in the epigenetic landscape of Treg cells from patients, which remained after treatment. These findings were further confirmed by intracellular cytokine staining, demonstrating that Treg cells exhibited inflammatory features and TNF production in chronic HCV infection that were maintained after viral clearance.

CONCLUSIONS

Overall, our results showed that during chronic HCV infection, the expanded Treg cell population acquired inflammatory features at phenotypic, transcriptomic, and epigenetic levels, which were maintained even after successful viral elimination by DAA treatment. Further studies are warranted to examine the clinical significance of sustained inflammatory features in the Treg cell population after recovery from chronic HCV infection.

IMPACT AND IMPLICATIONS

During chronic HCV infection, several immune components are altered both quantitatively and qualitatively. The recent introduction of direct-acting antivirals has led to high cure rates. Nevertheless, we have demonstrated that inflammatory features of Treg cells are maintained at phenotypic, transcriptomic, and epigenetic levels even after successful DAA treatment. Further in-depth studies are required to investigate the long-term clinical outcomes of patients who have recovered from chronic HCV infection.

Lower NKG2D expression in hepatic natural killer cells predicts poorer prognosis for chronic hepatitis B patients with cirrhosis

OBJECTIVE

Natural killer cells (NK) acts a central player of the immune system in liver cirrhosis. The aim of this study was to examine the expression of activating intra-hepatic NK cell group 2D (NKG2D) in patients with chronic hepatitis B (CHB) and analyzed the correlation between NKG2D expression and prognosis of liver cirrhosis in these patients.

METHODS

This was a cross-section study. Subjects with liver biopsy or sponge hemangioma surgery were included. The primary outcome was the NKG2D expression on intra-hepatic NK cells and their subtype cells in patients with CHB-related liver cirrhosis. Subsequently, the correlation of expression of NKG2D and clinical characteristic indicators were assayed RESULTS: Among 38 subjects, 11 (28.95%) normal liver sections adjacent the sponge hemangioma (healthy group) were collected during surgery, and 27 (71.05%) CHB-cirrhosis tissues (Cirrhosis group) were preserved after liver biopsy. Compared with healthy group, sections from cirrhosis group revealed more severe inflammation and collagen deposition and lower NKG2D expression in hepatic NK cells. The proportion of hepatic NK cells and the mean fluorescence intensity (MFI) of NKG2D on hepatic NK cells showed a positive correlation with serum albumin (Alb) level, platelet (Plt) count. Moreover, they had a significantly negative correlation with patient prothrombin time (PT), international standardized ratio (INR), the sirius red positive stained area and fibrosis stages.

CONCLUSIONS

Lower NKG2D expression in intra-hepatic NK cells may be predictive of poorer prognosis of CHB patients with cirrhosis.

CARs derived from broadly neutralizing, human monoclonal antibodies identified by single B cell sorting target hepatitis B virus-positive cells

To design new CARs targeting hepatitis B virus (HBV), we isolated human monoclonal antibodies recognizing the HBV envelope proteins from single B cells of a patient with a resolved infection. HBV-specific memory B cells were isolated by incubating peripheral blood mononuclear cells with biotinylated hepatitis B surface antigen (HBsAg), followed by single-cell flow cytometry-based sorting of live, CD19+ IgG+ HBsAg+ cells. Amplification and sequencing of immunoglobulin genes from single memory B cells identified variable heavy and light chain sequences. Corresponding immunoglobulin chains were cloned into IgG1 expression vectors and expressed in mammalian cells. Two antibodies named 4D06 and 4D08 were found to be highly specific for HBsAg, recognized a conformational and a linear epitope, respectively, and showed broad reactivity and neutralization capacity against all major HBV genotypes. 4D06 and 4D08 variable chain fragments were cloned into a 2nd generation CAR format with CD28 and CD3zeta intracellular signaling domains. The new CAR constructs displayed a high functional avidity when expressed on primary human T cells. CAR-grafted T cells proved to be polyfunctional regarding cytokine secretion and killed HBV-positive target cells. Interestingly, background activation of the 4D08-CAR recognizing a linear instead of a conformational epitope was consistently low. In a preclinical model of chronic HBV infection, murine T cells grafted with the 4D06 and the 4D08 CAR showed on target activity indicated by a transient increase in serum transaminases, and a lower number of HBV-positive hepatocytes in the mice treated. This study demonstrates an efficient and fast approach to identifying pathogen-specific monoclonal human antibodies from small donor cell numbers for the subsequent generation of new CARs.

Stat3 activation-triggered transcriptional networks govern the early stage of HBV-induced hepatic inflammation

The chronic carrier state of the hepatitis B virus (HBV) often leads to the development of liver inflammation as carriers age. However, the exact mechanisms that trigger this hepatic inflammation remain poorly defined. We analyzed the sequential processes during the onset of liver inflammation based on time-course transcriptome and transcriptional regulatory networks in an HBV transgenic (HBV-Tg) mice model and chronic HBV-infected (CHB) patients (data from GSE83148). The key transcriptional factor (TF) responsible for hepatic inflammation occurrence was identified and then validated both in HBV-Tg mice and liver specimens from young CHB patients. By time-course analysis, an early stage of hepatic inflammation was demonstrated in 3-month-old HBV-Tg mice: a marked upregulation of genes related to inflammation (Saa1/2, S100a8/9/11, or Il1β), innate immunity (Tlr2, Tlr7, or Tlr8), and cells chemotaxis (Ccr2, Cxcl1, Cxcl13, or Cxcl14). Within CHB samples, a unique early stage of inflammation activation was discriminated from immune tolerance and immune activation groups based on distinct gene expression patterns. Enhanced activation of TF Stat3 was strongly associated with increased inflammatory gene expression in this early stage of inflammation. Expression of phosphorylated Stat3 was higher in liver specimens from young CHB patients with relatively higher alanine aminotransferase levels. Specific inhibition of Stat3 activation significantly attenuated the degree of liver inflammation, the expression of inflammation-related genes, and the inflammatory monocytes and macrophages in 3-month-old HBV-Tg mice. Stat3 activation is essential for hepatic inflammation occurrence and is a novel indicator of early-stage immune activation in chronic HBV carriers.

IMPORTANCE

Until now, it remains a mystery that chronic hepatitis B virus (HBV)-infected patients in the "immune tolerance phase" will transition to the "immune activation phase" as they age. In this study, we reveal that Stat3 activation-triggered hepatic transcriptional alterations are distinctive characteristics of the early stage of immune/inflammation activation in chronic HBV infection. For the first time, we discover a mechanism that might trigger the transition from immune tolerance to immune activation in chronic HBV carriers.

Antimicrobial Treatment Challenges in the Management of Infective Spondylodiscitis Associated with Hemodialysis: A Comprehensive Review of Literature and Case Series Analysis

Infective spondylodiscitis (ISD), the infection of vertebral bodies and surrounding tissues, is a rare complication with major impact on the long-term survival of hemodialysis (HD) patients. Although the most frequent etiology is staphylococcal, identifying these pathogens in blood cultures and biopsy cultures is often difficult. This paper aims to present suitable antibiotic combinations for the treatment of these patients, which is usually challenging in the case of an unidentified pathogen. We presented the therapies applied for 13 HD patients and 19 patients without chronic kidney disease (CKD), diagnosed with ISD between 2013 and 2023 in Bihor County. The percentage of positive blood cultures was low in both groups (30.78% HD vs. 15.78% non-HD). The average length of antibiotic therapy was 5.15 weeks in HD patients and 6.29 weeks in non-HD patients. The use of Carbapenem alone (e.g., Meropenem) for an average of 19.6 days for patients in HD when the pathogen was not identified has proven to be efficient in most cases, similarly to using Vancomycin and Fluoroquinolone/Cephalosporines in combination. Regarding the non-CKD patients, the use of Clindamycin in various combinations for an average of 30.3 days has proven to be efficient in more than 90% of cases of ISD with a nonidentified pathogen. Within 2 years after ISD was diagnosed, 12 of the 13 HD patients passed away, mainly due to cardiovascular causes. Unfortunately, there are no guidelines in the literature concerning the empiric treatment of ISD in the particular case of HD patients. Upon checking the literature on PubMed and Google Scholar, only 10 studies provided relevant data regarding ISD treatment for HD patients. More data about the treatment and evolution of these patients is needed in order to elaborate a truly relevant metanalysis.

Hepatitis B virus-mediated sodium influx contributes to hepatic inflammation via synergism with intrahepatic danger signals

The NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome has been involved in the pathogenesis of various chronic liver diseases. However, its role in hepatitis B virus (HBV)-associated hepatitis remains unknown. Here we demonstrate the synergistic effect of HBV with potential intrahepatic danger signals on NLRP3 inflammasome activation. HBV exposure at the appropriate temporal points enhances potassium efflux-dependent NLRP3 inflammasome activation in macrophages and also increases NLRP3 inflammasome-mediated inflammation in HBV-transgenic mouse model. HBV-mediated synergism with intrahepatic signals represented by ATP molecules on NLRP3 activation was observed via relevance analysis, confocal microscopy, and co-immunoprecipitation, and its effector cytokines exhibit positive associations with hepatic inflammation in patients with severe hepatitis B. Furthermore, the synergism of HBV on NLRP3 inflammasome activation owes to increased sodium influx into macrophages. Our data demonstrate that HBV contributes to hepatic inflammation via sodium influx-dependent synergistic activation of NLRP3 inflammasome, which provides a deeper understanding of immune pathogenesis in HBV-associated hepatitis.

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

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

Hepatitis B Virus Reactivation with Immunosuppression: A Hidden Threat?

Hepatitis B virus (HBV) reactivation in the setting of immunosuppressive therapy is an increasingly recognized and preventable cause of elevated liver enzymes and clinical hepatitis in treated patients. However, not all immunosuppressive therapies confer the same risk. The purpose of this article was to review the literature on risks of HBV reactivation associated with immunosuppressive agents and propose a management algorithm. We searched Google Scholar, PubMed, and MEDLINE for studies related to hepatitis B reactivation and various immunosuppressive agents. The risk of HBV reactivation was found to differ by agent and depending on whether a patient had chronic HBV (HBsAg+) or past HBV (HBsAg-, anti-HBc+). The highest risk of reactivation (>10%) was associated with anti-CD20 agents and hematopoietic stem cell transplants. Multiple societies recommend HBV-specific anti-viral prophylaxis for patients with positive HBsAg prior to the initiation of immunosuppressive therapy, while the guidance for HBsAg- patients is more variable. Clinicians should check HBV status prior to beginning an immune-suppressive therapy. Patients with positive HBsAg should be initiated on antiviral prophylaxis in the majority of cases, whereas HBsAg- individuals should be evaluated on a case-by-case basis. Further research is required to determine the optimum duration of therapy.

Therapeutic potential of stem cells in regeneration of liver in chronic liver diseases: Current perspectives and future challenges

The deposition of extracellular matrix and hyperplasia of connective tissue characterizes chronic liver disease called hepatic fibrosis. Progression of hepatic fibrosis may lead to hepatocellular carcinoma. At this stage, only liver transplantation is a viable option. However, the number of possible liver donors is less than the number of patients needing transplantation. Consequently, alternative cell therapies based on non-stem cells (e.g., fibroblasts, chondrocytes, keratinocytes, and hepatocytes) therapy may be able to postpone hepatic disease, but they are often ineffective. Thus, novel stem cell-based therapeutics might be potentially important cutting-edge approaches for treating liver diseases and reducing patient' suffering. Several signaling pathways provide targets for stem cell interventions. These include pathways such as TGF-β, STAT3/BCL-2, NADPH oxidase, Raf/MEK/ERK, Notch, and Wnt/β-catenin. Moreover, mesenchymal stem cells (MSCs) stimulate interleukin (IL)-10, which inhibits T-cells and converts M1 macrophages into M2 macrophages, producing an anti-inflammatory environment. Furthermore, it inhibits the action of CD4+ and CD8+ T cells and reduces the activity of TNF-α and interferon cytokines by enhancing IL-4 synthesis. Consequently, the immunomodulatory and anti-inflammatory capabilities of MSCs make them an attractive therapeutic approach. Importantly, MSCs can inhibit the activation of hepatic stellate cells, causing their apoptosis and subsequent promotion of hepatocyte proliferation, thereby replacing dead hepatocytes and reducing liver fibrosis. This review discusses the multidimensional therapeutic role of stem cells as cell-based therapeutics in liver fibrosis.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Occult Hepatitis B Virus Infection and Liver Fibrosis in Chinese Patients

BACKGROUND

The impact of hepatitis B surface antigen (HBsAg)-negative/hepatitis B virus (HBV) DNA-positive occult HBV infection (OBI) on the severity of liver fibrosis remains unclear.

METHODS

A total of 1772 patients negative for HBsAg but positive for antibody to hepatitis B core antigen (HBcAg), stratified by the presence or absence of OBI, were selected for long-term carriage leading to elevation of ≥2 of 4 liver fibrosis indexes-hyaluronic acid (HA), laminin, type III procollagen peptide (PCIII), and type IV collagen (CIV)-at testing in a Chinese hospital. Patients were tested for serum viral load, HBV markers, and histopathological changes in liver biopsy specimens.

RESULTS

OBI was identified in 148 patients with liver fibrosis (8.4%), who had significantly higher levels of HA, laminin, PCIII, and CIV than 1624 fibrotic patients without OBI (P < .05). In 36 patients with OBI who underwent liver biopsy, significant correlations were observed between OBI viral load and serum HA levels (P = .01), PCIII levels (P = .01), and pathological histological activity index (HAI) scores (P < .001), respectively; HAI scores and PCIII levels (P = .04); HBcAg immunohistochemical scores and HA levels (P < .001); and HBcAg immunohistochemical scores and PCIII levels (P = .03). Positive fluorescent in situ hybridization results were significantly more frequent in patients with OBIs (80.6% vs 37.5% in those without OBIs). Among patients with OBIs, HBcAg was detected in the liver tissue in 52.8% and HBsAg in 5.6%.

CONCLUSIONS

OBI status appears to be associated with liver fibrosis severity.

HBV suppresses macrophage immune responses by impairing the TCA cycle through the induction of CS/PDHC hyperacetylation

BACKGROUND

It is now understood that HBV can induce innate and adaptive immune response disorders by affecting immunosuppressive macrophages, resulting in chronic HBV infection. However, the underlying mechanism is not fully understood. Dysregulated protein acetylation can reportedly influence the differentiation and functions of innate immune cells by coordinating metabolic signaling. This study aims to assess whether HBV suppresses macrophage-mediated innate immune responses by affecting protein acetylation and to elucidate the underlying mechanisms of HBV immune escape.

METHODS

We investigated the effect of HBV on the acetylation levels of human THP-1 macrophages and identified potential targets of acetylation that play a role in glucose metabolism. Metabolic and immune phenotypes of macrophages were analyzed using metabolomic and flow cytometry techniques. Western blot, immunoprecipitation, and immunofluorescence were performed to measure the interactions between deacetylase and acetylated targets. Chronic HBV persistent infected mice were established to evaluate the role of activating the tricarboxylic acid (TCA) cycle in macrophages for HBV clearance.

RESULTS

Citrate synthase/pyruvate dehydrogenase complex hyperacetylation in macrophages after HBV stimulation inhibited their enzymatic activities and was associated with impaired TCA cycle and M2-like polarization. HBV downregulated Sirtuin 3 (SIRT3) expression in macrophages by means of the toll-like receptor 2 (TLR2)-NF-κB- peroxisome proliferatoractivated receptor γ coactivator 1α (PGC-1α) axis, resulting in citrate synthase/pyruvate dehydrogenase complex hyperacetylation. In vivo administration of the TCA cycle agonist dichloroacetate inhibited macrophage M2-like polarization and effectively reduced the number of serum HBV DNA copies.

CONCLUSIONS

HBV-induced citrate synthase/pyruvate dehydrogenase complex hyperacetylation negatively modulates the innate immune response by impairing the TCA cycle of macrophages. This mechanism represents a potential therapeutic target for controlling HBV infection.

Hepatitis B Virus Epsilon (ε) RNA Element: Dynamic Regulator of Viral Replication and Attractive Therapeutic Target

Hepatitis B virus (HBV) chronically infects millions of people worldwide, which underscores the importance of discovering and designing novel anti-HBV therapeutics to complement current treatment strategies. An underexploited but attractive therapeutic target is ε, a cis-acting regulatory stem-loop RNA situated within the HBV pregenomic RNA (pgRNA). The binding of ε to the viral polymerase protein (P) is pivotal, as it triggers the packaging of pgRNA and P, as well as the reverse transcription of the viral genome. Consequently, small molecules capable of disrupting this interaction hold the potential to inhibit the early stages of HBV replication. The rational design of such ligands necessitates high-resolution structural information for the ε-P complex or its individual components. While these data are currently unavailable for P, our recent structural elucidation of ε through solution nuclear magnetic resonance spectroscopy marks a significant advancement in this area. In this review, we provide a brief overview of HBV replication and some of the therapeutic strategies to combat chronic HBV infection. These descriptions are intended to contextualize our recent experimental efforts to characterize ε and identify ε-targeting ligands, with the ultimate goal of developing novel anti-HBV therapeutics.

Increased liver stiffness promotes hepatitis B progression by impairing innate immunity in CCl4-induced fibrotic HBV+ transgenic mice

Background

Hepatitis B virus (HBV) infection develops as an acute or chronic liver disease, which progresses from steatosis, hepatitis, and fibrosis to end-stage liver diseases such as cirrhosis and hepatocellular carcinoma (HCC). An increased stromal stiffness accompanies fibrosis in chronic liver diseases and is considered a strong predictor for disease progression. The goal of this study was to establish the mechanisms by which enhanced liver stiffness regulates HBV infectivity in the fibrotic liver tissue.

Methods

For in vitro studies, HBV-transfected HepG2.2.15 cells were cultured on polydimethylsiloxane gels coated by polyelectrolyte multilayer films of 2 kPa (soft) or 24 kPa (stiff) rigidity mimicking the stiffness of the healthy or fibrotic liver. For in vivo studies, hepatic fibrosis was induced in C57Bl/6 parental and HBV+ transgenic (HBVTg) mice by injecting CCl4 twice a week for 6 weeks.

Results

We found higher levels of HBV markers in stiff gel-attached hepatocytes accompanied by up-regulated OPN content in cell supernatants as well as suppression of anti-viral interferon-stimulated genes (ISGs). This indicates that pre-requisite "fibrotic" stiffness increases osteopontin (OPN) content and releases and suppresses anti-viral innate immunity, causing a subsequent rise in HBV markers expression in hepatocytes. In vitro results were corroborated by data from HBVTg mice administered CCl4 (HBVTg CCl4). These mice showed higher HBV RNA, DNA, HBV core antigen (HBcAg), and HBV surface antigen (HBsAg) levels after liver fibrosis induction as judged by a rise in Col1a1, SMA, MMPs, and TIMPs mRNAs and by increased liver stiffness. Importantly, CCl4-induced the pro-fibrotic activation of liver cells, and liver stiffness was higher in HBVTg mice compared with control mice. Elevation of HBV markers and OPN levels corresponded to decreased ISG activation in HBVTg CCl4 mice vs HBVTg control mice.

Conclusion

Based on our data, we conclude that liver stiffness enhances OPN levels to limit anti-viral ISG activation in hepatocytes and promote an increase in HBV infectivity, thereby contributing to end-stage liver disease progression.

Plasma Pattern of Extracellular Vesicles Isolated from Hepatitis C Virus Patients and Their Effects on Human Vascular Endothelial Cells

Hepatitis C virus (HCV) patients are at increased risk of cardiovascular disease (CVD). In this study, we aimed to evaluate the role of extracellular vesicles (EVs) as pathogenic factors for the onset of HCV-related endothelial dysfunction. Sixty-five patients with various stages of HCV-related chronic liver disease were enrolled in this case series. Plasma EVs were characterized and used to stimulate human vascular endothelial cells (HUVEC), which were examined for cell viability, mitochondrial membrane potential, and reactive oxygen species (ROS) release. The results showed that EVs from HCV patients were mainly of endothelial and lymphocyte origin. Moreover, EVs were able to reduce cell viability and mitochondrial membrane potential of HUVEC, while increasing ROS release. Those harmful effects were reduced by the pretreatment of HUVEC with the NLR family pyrin domain containing 3 (NLRP3)/AMP-activated protein kinase and protein kinase B blockers. In conclusion, in HCV patients, we could highlight a circulating pattern of EVs capable of inducing damage to the endothelium. These data represent a novel possible pathogenic mechanism underlying the reported increase of CVD occurrence in HCV infection and could be of clinical relevance also in relation to the widespread use of antiviral drugs.

Immunological scars after cure of hepatitis C virus infection: Long-HepC?

Hepatitis C virus (HCV) infection provides a unique opportunity to study the effects of spontaneous or treatment-induced viral elimination on the human immune system. Twenty to 50% of patients with acute HCV infection spontaneously clear the virus, which is related to the quality of the individual's immune response, while the chronic infection is associated with an altered and impaired immune response. Direct-acting antiviral agents are now available that provide sustained viral elimination in more than 95% of patients with chronic HCV infection. Viral elimination leads to a decrease in disease sequelae such as cirrhosis and hepatocellular carcinoma, and extrahepatic manifestations also improve. However, some patients may still experience long-term complications, and viral elimination does not protect against HCV reinfection. This review addresses the question of whether the altered and impaired immune response caused by HCV normalizes after viral elimination and if this may affect the long-term clinical course after HCV cure.

Immune predictors of hepatitis B surface antigen seroconversion in patients with hepatitis B reactivation

BACKGROUND

Hepatitis B surface antigen (HBsAg) seroconversion is sometimes observed in hepatitis B reactivation (rHBV), probably due to immune resetting and differentiation.

AIMS

To investigate sequential immune differentiation and abrogation of tolerance in patients with rHBV who achieved HBsAg seroconversion.

METHODS

We included 19 patients with chronic hepatitis B (CHBV; HBV DNA log10^3-8 ), 67 with rHBV (raised ALT [>5XULN], HBV DNAlog10^4-8 ) and 10 healthy controls. Immune differentiation, tolerance and functional status of CD4, CD8, T regulatory cells (Tregs), B cells and follicular T helper (Tfh) cells were assessed at baseline and 24 weeks.

RESULTS

At 24 weeks, 81% rHBV (n = 67) lost HBV DNA and HBeAg (41%), and 12 (19%) lost HBsAg and made anti-HBs titers >10 IU/ml. rHBV patients had higher Th1/17, T_EM , Tfh, Tfh1/17, plasma and ATM B cells, and lower Tregs, Th2, Th17 and TEMRA expression. rHBV showed lower PD1, TIM3, LAG3, SLAM and TOX compared to CHBV. There was a significant increase in CD8, CD8EM, Tfh, Tfh1/17 and plasma B cells in seroconverters than non-seroconverters. At 24 weeks, we also observed increased plasma B cell frequency in seroconverters. While non-seroconverters showed higher expression of PD1, TIM3, LAG3, SLAM and TOX on CD4/CD8 T cells, blockade of PD1, TIM3, LAG3 and CTLA4 significantly enhanced IFN-γ, TNF-α, IL-4 and IL-21 expression on CD4/CD8 and Tfh cells in non-seroconverters.

CONCLUSIONS

Non-seroconverters have increased inhibitory markers on CD4/CD8 T cells. There is a critical play of CD8, Tfh and B cells and subsets in seroclearance, along with checkpoint molecules as a potential therapy for non-seroconverters in HBV infection.

T Cell Response to SARS-CoV-2 Coinfection and Comorbidities

For the past three years, COVID-19 has become an increasing global health issue. Adaptive immune cells, especially T cells, have been extensively investigated in regard to SARS-CoV-2 infection. However, human health and T cell responses are also impacted by many other pathogens and chronic diseases. We have summarized T cell performance during SARS-CoV-2 coinfection with other viruses, bacteria, and parasites. Furthermore, we distinguished if those altered T cell statuses under coinfection would affect their clinical outcomes, such as symptom severity and hospitalization demand. T cell alteration in diabetes, asthma, and hypertension patients with SARS-CoV-2 infection was also investigated in our study. We have summarized whether changes in T cell response influence the clinical outcome during comorbidities.

Reactivation of occult hepatitis B virus infection in a renal transplant recipient

We report a case of hepatitis B virus (HBV) reactivation in a renal transplant recipient. Reactivation manifested as an occult infection with detectable HBV-DNA and negativity for hepatitis B surface antigen (HBsAg). The anti-HBs antibody titre was above the protective threshold and continued to rise, to 951.36 mIU/ml, after HBV reactivation. Sequencing revealed multiple vaccine- and diagnostic-escape mutations in the major hydrophilic region of HBsAg. This case demonstrates both reactivation of an HBV escape mutant in a vaccinated patient and host immunity after virus mutation.

Correlation between COVID-19 and hepatitis B: A systematic review

BACKGROUND

There is growing evidence that patients with coronavirus disease 2019 (COVID-19) frequently present with liver impairment. Hepatitis B virus (HBV) remains a major public health threat in current society. Both severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and HBV can cause liver damage, and current findings on whether HBV infection increases disease severity in COVID-19 patients are inconsistent, and whether SARS-CoV-2 infection accelerates hepatitis B progression or leads to a worse prognosis in hepatitis B patients has not been adequately elucidated.

AIM

To explore the complex relationship between COVID-19 and hepatitis B in order to inform the research and management of patients co-infected with SARS-CoV-2 and HBV.

METHODS

An experienced information specialist searched the literature in the following online databases: PubMed, China National Knowledge Infrastructure, Google Scholar, Scopus, Wiley, Web of Science, Cochrane, and ScienceDirect. The literature published from December 2019 to September 1, 2022 was included in the search. We also searched medRxiv and bioRxiv for gray literature and manually scanned references of included articles. Articles reporting studies conducted in humans discussing hepatitis B and COVID-19 were included. We excluded duplicate publications. News reports, reports, and other gray literature were included if they contained quantifiable evidence (case reports, findings, and qualitative analysis). Some topics that included HBV or COVID-19 samples but did not have quantitative evidence were excluded from the review.

RESULTS

A total of 57 studies were eligible and included in this review. They were from 11 countries, of which 33 (57.9%) were from China. Forty-two of the 57 studies reported abnormalities in liver enzymes, three mainly reported abnormalities in blood parameters, four indicated no significant liver function alterations, and another eight studies did not provide data on changes in liver function. Fifty-seven studies were retrospective and the total number of co-infections was 1932, the largest sample size was 7723, and the largest number of co-infections was 353. Most of the studies suggested an interaction between hepatitis B and COVID-19, while 12 studies clearly indicated no interaction between hepatitis B and COVID-19. Six of the 57 studies clearly reported HBV activation. Six studies were related to liver transplant patients.

CONCLUSION

There is some association between COVID-19 and hepatitis B. Future high-quality randomized trials are needed to further elucidate the interaction between COVID-19 and hepatitis B.

Hepatitis B virus pathogenesis relevant immunosignals uncovering amino acids utilization related risk factors guide artificial intelligence-based precision medicine

Background: Although immune microenvironment-related chemokines, extracellular matrix (ECM), and intrahepatic immune cells are reported to be highly involved in hepatitis B virus (HBV)-related diseases, their roles in diagnosis, prognosis, and drug sensitivity evaluation remain unclear. Here, we aimed to study their clinical use to provide a basis for precision medicine in hepatocellular carcinoma (HCC) via the amalgamation of artificial intelligence. Methods: High-throughput liver transcriptomes from Gene Expression Omnibus (GEO), NODE (https://www.bio.sino.org/node), the Cancer Genome Atlas (TCGA), and our in-house hepatocellular carcinoma patients were collected in this study. Core immunosignals that participated in the entire diseases course of hepatitis B were explored using the "Gene set variation analysis" R package. Using ROC curve analysis, the impact of core immunosignals and amino acid utilization related gene on hepatocellular carcinoma patient's clinical outcome were calculated. The utility of core immunosignals as a classifier for hepatocellular carcinoma tumor tissue was evaluated using explainable machine-learning methods. A novel deep residual neural network model based on immunosignals was constructed for the long-term overall survival (LS) analysis. In vivo drug sensitivity was calculated by the "oncoPredict" R package. Results: We identified nine genes comprising chemokines and ECM related to hepatitis B virus-induced inflammation and fibrosis as CLST signals. Moreover, CLST was co-enriched with activated CD4+ T cells bearing harmful factors (aCD4) during all stages of hepatitis B virus pathogenesis, which was also verified by our hepatocellular carcinoma data. Unexpectedly, we found that hepatitis B virus-hepatocellular carcinoma patients in the CLST^highaCD4^high subgroup had the shortest overall survival (OS) and were characterized by a risk gene signature associated with amino acids utilization. Importantly, characteristic genes specific to CLST/aCD4 showed promising clinical relevance in identifying patients with early-stage hepatocellular carcinoma via explainable machine learning. In addition, the 5-year long-term overall survival of hepatocellular carcinoma patients can be effectively classified by CLST/aCD4 based GeneSet-ResNet model. Subgroups defined by CLST and aCD4 were significantly involved in the sensitivity of hepatitis B virus-hepatocellular carcinoma patients to chemotherapy treatments. Conclusion: CLST and aCD4 are hepatitis B virus pathogenesis-relevant immunosignals that are highly involved in hepatitis B virus-induced inflammation, fibrosis, and hepatocellular carcinoma. Gene set variation analysis derived immunogenomic signatures enabled efficient diagnostic and prognostic model construction. The clinical application of CLST and aCD4 as indicators would be beneficial for the precision management of hepatocellular carcinoma.

Resident macrophages of the lung and liver: The guardians of our tissues

Resident macrophages play a unique role in the maintenance of tissue function. As phagocytes, they are an essential first line defenders against pathogens and much of the initial characterization of these cells was focused on their interaction with viral and bacterial pathogens. However, these cells are increasingly recognized as contributing to more than just host defense. Through cytokine production, receptor engagement and gap junction communication resident macrophages tune tissue inflammatory tone, influence adaptive immune cell phenotype and regulate tissue structure and function. This review highlights resident macrophages in the liver and lung as they hold unique roles in the maintenance of the interface between the circulatory system and the external environment. As such, we detail the developmental origin of these cells, their contribution to host defense and the array of tools these cells use to regulate tissue homeostasis.

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.

MCPIP-1-Mediated Immunosuppression of Neutrophils Exacerbates Acute Bacterial Peritonitis and Liver Injury

Monocyte chemotactic protein-1-induced protein-1 (MCPIP-1) is highly expressed in activated immune cells and negatively regulates immune responses, while the mechanisms underlying the immunoregulation of neutrophils in acute bacterial infection and liver injury remain elusive. Here, we examined the role of MCPIP-1 in regulating neutrophil functions during acute bacterial peritonitis and liver injury. Mice with myeloid cell-specific overexpression (McpipMye-tg) or knockout (McpipΔMye) of MCPIP-1 were generated. We found that reactive oxygen species and myeloperoxidase production, formation of neutrophil extracellular traps, and migratory capacity were deficient in McpipMye-tg neutrophils but enhanced in McpipΔMye neutrophils. The recruitment of neutrophils and pathogen clearance were markedly suppressed in McpipMye-tg mice following intraperitoneal infection with Salmonella typhimurium while intensified in McpipΔMye mice. Severe acute S. typhimurium-infected peritonitis and liver injury occurred in McpipMye-tg mice but were alleviated in McpipΔMye mice. RNA sequencing, RNA-binding protein immunoprecipitation and qPCR analysis revealed that MCPIP-1 downregulated the protective functions of neutrophils via degrading the mRNA of cold inducible RNA-binding protein. Consistently, MCPIP-1 was highly expressed in neutrophils of patients with acute infectious diseases, especially in those with liver injury. Collectively, we uncover that MCPIP-1 negatively regulates the antibacterial capacities of neutrophils, leading to exacerbating severe acute bacterial peritonitis and liver injury. It may serve as a candidate target for maintaining neutrophil homeostasis to control acute infectious diseases.

[Natural history and disease progression of chronic hepatitis B virus infection]

OBJECTIVE

To better understand and revise the natural history and disease progression of chronic hepatitis B virus (HBV) infection through analysis of a single-center large-scale cohort of indivi-duals with chronic HBV infection.

METHODS

Patients with chronic HBV infection who had undergone liver biopsy in the Fifth Medical Center of Chinese People's Liberation Army (PLA) General Hospital from January 2014 to October 2020 were retrospectively recruited. Based on patient's hepatitis B e antigen (HBeAg) states and pathologic diagnosis, they were categorized into four disease progression statuses (or phases according to the old-terminology in the updated guidelines of chronic hepatitis B (CHB), such as European Association for the Study of the Liver (EASL) 2017, Clinical Practice Guidelines on the Management of Hepatitis B Virus Infection: HBeAg-positive chronic HBV infection (immune tolerance), HBeAg-positive CHB (immune active HBeAg positive), HBeAg-negative chronic HBV infection (inactive carrier), and HBeAg-negative CHB (immune reactive HBeAg negative). Then the demographic, laboratory tests and liver histological results of the patients in different disease progression stages were compared. Age differences between the two groups were evaluated using Mann-Whitney U test.

RESULTS

A total of 760 eligible patients with a median age of 29 (interquartile range: 16-39) years were enrolled. Among them, 197 were underage individuals (age < 18 years) and 563 were adults; and 456 were males and 304 females. According to the pathological diagnosis, the patients were classified, and in each of the above four natural disease phases there were 173, 329, 95, and 163 individuals, respectively. Further comparison of the ages of the patients of the four disease progression statuses revealed that patients of HBeAg-negative CHB had a median age at 37 years, which was reasonably higher than those with HBeAg-positive CHB in immune active phase (37 vs. 24 years, P < 0.001), but was relatively younger than those with HBeAg-negative chronic HBV infection (37 vs. 39 years, P= 0.240).

CONCLUSION

According to this study, it could be speculated that HBeAg-negative CHB patients probably not all reactivate from individuals of HBeAg-negative chronic HBV infection. Instead, certain HBeAg-negative CHB patients may also come from HBeAg-positive CHB patients who have undergone HBeAg clearance or seroconversion and still remain in the immune active state.

HCV and tumor-initiating stem-like cells

Neoplasms contain tumor-initiating stem-like cells (TICs) that are characterized by increased drug resistance. The incidence of many cancer types have trended downward except for few cancer types, including hepatocellular carcinoma (HCC). Therefore mechanism of HCC development and therapy resistance needs to be understood. These multiple hits by hepatitis C virus (HCV) eventually promotes transformation and TIC genesis, leading to HCC development. This review article describes links between HCV-associated HCC and TICs. This review discusses 1) how HCV promotes genesis of TICs and HCC development; 2) how this process avails itself as a novel therapeutic target for HCC treatment; and 3) ten hall marks of TIC oncogenesis and HCC development as targets for novel therapeutic modalities.

Current treatment of chronic hepatitis B: Clinical aspects and future directions

Hepatitis B virus (HBV) infection is a public health threat worldwide, and there is no direct treatment yet available. In the event of infection, patients may present liver cirrhosis and cancer, which threaten the patients’ health globally, especially in the Asia-Pacific region and China. In 2019, Chinese hepatopathologists updated the 2015 Guidelines for the Prevention and Treatment of Chronic Hepatitis B as the clinical reference. The other versions formulated by the American Association for the Study of Liver Diseases (2018 AASLD guidelines) (AASLD, 2018), European Association for the Study of the Liver (2017 EASL guidelines) (EASL, 2017), and Asian-Pacific Association for the Study of the Liver (2015 APASL guidelines) (APASL, 2015) also provide clinical guidance. However, there are still some issues that need to be addressed. In the present study, the following aspects will be introduced successively: (1) Who should be treated in the general population according to the guidelines; (2) Treatment of specific populations infected with HBV; (3) Controversial issues in clinical practice; (4) Perspective.

The evolving role of tissue-resident memory T cells in infections and cancer

Resident memory T cells (TRM) form a distinct type of T memory cells that stably resides in tissues. TRM form an integral part of the immune sensing network and have the ability to control local immune homeostasis and participate in immune responses mediated by pathogens, cancer, and possibly autoantigens during autoimmunity. TRM express residence gene signatures, functional properties of both memory and effector cells, and remarkable plasticity. TRM have a well-established role in pathogen immunity, whereas their role in antitumor immune responses and immunotherapy is currently evolving. As TRM form the most abundant T memory cell population in nonlymphoid tissues, they are attractive targets for therapeutic exploitation. Here, we provide a concise review of the development and physiological role of CD8+ TRM, their involvement in diseases, and their potential therapeutic exploitation.

Single MHC-I Expression Promotes Virus-Induced Liver Immunopathology

Major histocompatibility complex I (MHC-I) molecules present epitopes on the cellular surface of antigen-presenting cells to prime cytotoxic clusters of differentiation 8 (CD8)⁺ T cells (CTLs), which then identify and eliminate other cells such as virus-infected cells bearing the antigen. Human hepatitis virus cohort studies have previously identified MHC-I molecules as promising predictors of viral clearance. However, the underlying functional significance of these predictions is not fully understood. Here, we show that expression of single MHC-I isomers promotes virus-induced liver immunopathology. Specifically, using the lymphocytic choriomeningitis virus (LCMV) model system, we found MHC-I proteins to be highly up-regulated during infection. Deletion of one of the two MHC-I isomers histocompatibility antigen 2 (H2)-Db or H2-Kb in C57Bl/6 mice resulted in CTL activation recognizing the remaining MHC-I with LCMV epitopes in increased paucity. This increased CTL response resulted in hepatocyte death, increased caspase activation, and severe metabolic changes in liver tissue following infection with LCMV. Moreover, depletion of CTLs abolished LCMV-induced pathology in these mice with resulting viral persistence. In turn, natural killer (NK) cell depletion further increased antiviral CTL immunity and clearance of LCMV even in the presence of a single MHC-I isomer. Conclusion: Our results suggest that uniform MHC-I molecule expression promotes enhanced CTL immunity during viral infection and contributes to increased CTL-mediated liver cell damage that was alleviated by CD8 or NK cell depletion.

Transcriptional Pattern Analysis of Virus-Specific CD8+ T Cells in Hepatitis C Infection: Increased Expression of TOX and Eomesodermin During and After Persistent Antigen Recognition

Thymocyte selection-associated high mobility group box (TOX) has been described to be a key regulator in the formation of CD8+ T cell exhaustion. Hepatitis C virus (HCV) infection with different lengths of antigen exposure in acute, chronic, and after resolution of HCV infection is the ideal immunological model to study the expression of TOX in HCV-specific CD8+ T cells with different exposure to antigen. HCV-specific CD8+ T cells from 35 HLA-A*01:01, HLA-A*02:01, and HLA-A*24:02 positive patients were analyzed with a 16-color FACS-panel evaluating the surface expression of lineage markers (CD3, CD8), ectoenzymes (CD39, CD73), markers of differentiation (CD45RO, CCR7, CD127), and markers of exhaustion and activation (TIGIT, PD-1, KLRG1, CD226) and transcription factors (TOX, Eomesodermin, T-bet). Here, we defined on-target T cells as T cells against epitopes without escape mutations and off-target T cells as those against a "historical" antigen mutated in the autologous sequence. TOX+HCV-specific CD8+ T cells from patients with chronic HCV and on-target T cells displayed co-expression of Eomesodermin and were associated with the formation of terminally exhausted CD127-PD1hi, CD39hi, CD73low CD8+ T cells. In contrast, TOX+HCV-specific CD8+ T cells in patients with off-target T cells represented a progenitor memory Tex phenotype characterized by CD127hi expression and a CD39low and CD73hi phenotype. TOX+HCV-specified CD8+ T cells in patients with a sustained virologic response were characterized by a memory phenotype (CD127+, CD73hi) and co-expression of immune checkpoints and Eomesodermin, indicating a key structure in priming of HCV-specific CD8+ T cells in the chronic stage, which persisted as a residual after therapy. Overall, the occurrence of TOX+HCV-specific CD8+ T cells was revealed at each disease stage, which impacted the development of progenitor Tex, intermediate Tex, and terminally exhausted T cell through an individual molecular footprint. In sum, TOX is induced early during acute infection but is modulated by changes in viral sequence and antigen recognition. In the case of antigen persistence, the interaction with Eomesodermin leads to the formation of terminally exhausted virus-specific CD8+ T cells, and there was a direct correlation of the co-expression of TOX and Eomes and terminally exhausted phenotype of virus-specific CD8+ T cells.

Role of the chemokine system in liver fibrosis: a narrative review

BACKGROUND AND OBJECTIVE

Liver fibrosis is a disease with characteristics of an aberrant wound healing response. Fibrosis is commonly the end-stage for chronic liver diseases like alcohol-associated liver disease (ALD), metabolic-associated liver disease, viral hepatitis, and hepatic autoimmune disease. Innate immunity contributes to the progression of many diseases through multiple mechanisms including production of pro-inflammatory mediators, leukocyte infiltration and tissue injury. Chemokines and their receptors orchestrate accumulation and activation of immune cells in tissues and are associated with multiple liver diseases; however, much less is known about their potential roles in liver fibrosis. This is a narrative review of current knowledge of the relationship of chemokine biology to liver fibrosis with insights into potential future therapeutic opportunities that can be explored in the future.

METHODS

A comprehensive literature review was performed searching PubMed for relevant English studies and texts regarding chemokine biology, chronic liver disease and liver fibrosis published between 1993 and 2021. The review was written and constructed to detail the intriguing chemokine biology, the relation of chemokines to tissue injury and resolution, and identify areas of discovery for fibrosis treatment.

KEY CONTENT AND FINDINGS

Chemokines are implicated in many chronic liver diseases, regardless of etiology. Most of these diseases will progress to fibrosis without appropriate treatment. The contributions of chemokines to liver disease and fibrosis are diverse and include canonical roles of modulating hepatic inflammation as well as directly contributing to fibrosis via activation of hepatic stellate cells (HSCs). Limited clinical evidence suggests that targeting chemokines in certain liver diseases might provide a therapeutic benefit to patients with hepatic fibrosis.

CONCLUSIONS

The chemokine system of ligands and receptors is a complex network of inflammatory signals in nearly all diseases. The specific sources of chemokines and cellular targets lend unique pathophysiological consequences to chronic liver diseases and established fibrosis. Although most chemokines are pro-inflammatory and contribute to tissue injury, others likely aid in the resolution of established fibrosis. To date, very few targeted therapies exist for the chemokine system and liver disease and/or fibrosis, and further study could identify viable treatment options to improve outcomes in patients with end-stage liver disease.

MAIT cells in liver inflammation and fibrosis

Mucosal-associated invariant T cells or MAIT cells are an abundant cell type in humans and especially so in the liver. MAIT cells are a subset of T lymphocytes that sit at a bridge between innate and adaptive immunity, so-called innate-like or "unconventional" T cells. The specificity of their antigen receptor (T cell receptor or TCR) is for the conserved major histocompatibility complex (MHC)-related molecule MR1, which presents a modified bacterial metabolite from the vitamin B2 biosynthesis pathway - this allows them to respond in the presence of many bacteria or yeast. MAIT cells also possess an array of cytokine receptors, which allows triggering independently of the TCR. The combination of such signals drives their functionality - this means they can respond to a range of stimuli and likely play a role not only in infection or inflammation, but also under homeostatic conditions.In this review, we will look at the question of what MAIT cells are doing in the normal liver and how they behave in the setting of disease. These questions are of relevance because MAIT cells are such a distinctive cell type enriched in the liver under normal conditions, and their modulation could be of therapeutic benefit. The recent discovery that they appear to be involved in liver fibrosis is particularly of interest in this context.

The Dynamic Role of NK Cells in Liver Cancers: Role in HCC and HBV Associated HCC and Its Therapeutic Implications

Hepatocellular carcinoma (HCC) remains an important complication of chronic liver disease, especially when cirrhosis occurs. Existing treatment strategies include surgery, loco-regional techniques, and chemotherapy. Natural killer cells are distinctive cytotoxic lymphocytes that play a vital role in fighting tumors and infections. As an important constituent of the innate immune system against cancer, phenotypic and functional deviations of NK cells have been demonstrated in HCC patients who also exhibit perturbation of the NK-activating receptor/ligand axis. The rate of recurrence of tumor-infiltrating and circulating NK cells are positively associated with survival benefits in HCC and have prognostic significance, suggesting that NK cell dysfunction is closely related to HCC progression. NK cells are the first-line effector cells of viral hepatitis and play a significant role by directly clearing virus-infected cells or by activating antigen-specific T cells by producing IFN-γ. In addition, chimeric antigen receptor (CAR) engineered NK cells suggest an exclusive opportunity to produce CAR-NKs with several specificities with fewer side effects. In the present review, we comprehensively discuss the innate immune landscape of the liver, particularly NK cells, and the impact of tumor immune microenvironment (TIME) on the function of NK cells and the biological function of HCC. Furthermore, the role of NK cells in HCC and HBV-induced HCC has also been comprehensively elaborated. We also elaborate on available NK cell-based immunotherapeutic approaches in HCC treatment and summarize current advancements in the treatment of HCC. This review will facilitate researchers to understand the importance of the innate immune landscape of NK cells and lead to devising innovative immunotherapeutic strategies for the systematic treatment of HCC.

Association Between Depression or Anxiety and the Risk of Hepatitis B Flares: A Nationwide Population-Based Cohort Study

Purpose

Depression and anxiety have been reported to increase the risk of infectious diseases and reactivation of latent infection. We conducted a nationwide population-based retrospective cohort study to determine the relationship between hepatitis B flares and depression or anxiety, utilizing outpatient and inpatient data from the Taiwan National Health Insurance Research database collected from 2000 to 2015.

Patients and Methods

A total of 12,992 patients with chronic hepatitis B and newly diagnosed anxiety/depression, without advanced liver disease, were propensity score-matched for age, sex, and comorbidities in a 1:4 ratio to 51,968 controls with chronic hepatitis B without depression/anxiety or advanced liver disease. Both groups were followed-up until December 31, 2015. Cox proportional hazards regression was used to determine the risk factors for hepatitis B flares. The Log rank test and Kaplan-Meier analysis were performed to assess differences in the cumulative incidence of hepatitis B flares according to anxiety/depression status.

Results

The incidence of hepatitis B flares was higher in the depression/anxiety cohort than in the control cohort (log-rank; p < 0.001). Patients with depression/anxiety had a significantly higher incidence rate of hepatitis B flares than those without depression/anxiety (3017 per 105 person-years versus 2042 per 105 person-years, p = 0.003). After adjusting for age and comorbidities, anxiety/depression was independently associated with an increased risk of hepatitis B flares (hazard ratio, 1.173; 95% confidence interval, 1.033-1.277; p = 0.003).

Conclusion

This analysis suggests that in patients with chronic hepatitis B without advanced liver disease, those with concomitant depression or anxiety may be at higher risk of hepatitis B flares.

Mouse Models of Liver Parenchyma Injuries and Regeneration

Mice have genetic and physiological similarities with humans and a well-characterized genetic background that is easy to manipulate. Murine models have become the most favored, robust mammalian systems for experimental analyses of biological processes and disease conditions due to their low cost, rapid reproduction, a wealth of mouse strains with defined genetic conditions (both native ones as well as ones established experimentally), and high reproducibility with respect to that which can be done in experimental studies. In this review, we focus on murine models for liver, an organ with renown regenerative capacity and the organ most central to systemic, complex metabolic and physiological functions for mammalian hosts. Establishment of murine models has been achieved for all aspects of studies of normal liver, liver diseases, liver injuries, and regenerative repair mechanisms. We summarize key information on current mouse systems that partially model facets of clinical scenarios, particularly those associated with drug-induced acute or chronic liver injuries, dietary related, non-alcoholic liver disease (NAFLD), hepatitis virus infectious chronic liver diseases, and autoimmune hepatitis (AIH). In addition, we also include mouse models that are suitable for studying liver cancers (e.g., hepatocellular carcinomas), the aging process (senescence, apoptosis), and various types of liver injuries and regenerative processes associated with them.

Proteomic characterization of the natural history of chronic HBV infection revealed by tandem mass tag-based quantitative proteomics approach

Currently, determining when to start antiviral therapy in patients with chronic HBV infection is a controversial issue. One crucial reason is that biomarkers for distinguishing the natural history of chronic HBV infection are unmet needs. In this study, we aimed to explore novel biomarkers and therapeutic targets for the diagnosis and treatment of chronic HBV infection by using tandem mass tag (TMT)-based quantitative proteomics approach. Here, we firstly revealed the serum proteomic characterization of the natural history of chronic HBV infection using multiplex TMT labeling coupled with liquid chromatography-mass spectrometry. Then, we verified the levels of differentially expressed proteins (DEPs) across a large number of clinical samples by enzyme-linked immunosorbent assay (ELISA). We found that DEPs over the different phases of chronic HBV infection were primarily involved in the biological process of leukocyte-mediated immunity. Patients with chronic hepatitis were characterized as having an up-regulated proteasome pathway, including upregulation of proteasome activator subunit 1 (PSME1) and proteasome subunit alpha type 7 (PSMA7) levels. In addition, immune tolerant phase patients were characterized by having the lowest ephrin-B2 (EFNB2) levels and highest heat responsive protein 12 (HRSP12) levels. Moreover, inactive HBV carrier state patients were characterized by having a down-regulated glycolysis/gluconeogenesis pathway, with especially low expression of related enzymes alpha-enolase (ENO1) and fructose-1,6-bisphosphatase 1 (FBP1). What's more, HBeAg-negative chronic hepatitis patients were characterized as having the highest interleukin 18 binding protein (IL-18BP) levels. Thus, our results provide several potential diagnostic biomarkers for distinguishing the natural history of chronic HBV infection, such as PSME1, PSMA7, EFNB2, ENO1, and IL-18BP, and also present potential therapeutic interventions for chronic hepatitis B patients, such as targeting the proteasome or glycolysis/gluconeogenesis pathways. Our findings shed new light on the development of novel diagnostic biomarkers and therapeutic targets for the diagnosis and treatment of chronic HBV infection.

TIGIT Signaling Pathway Regulates Natural Killer Cell Function in Chronic Hepatitis B Virus Infection

Background and Objective

Persistent infection of hepatitis B virus (HBV) and liver damage in immune active chronic hepatitis B (CHB) could be partly due to the overreaction of natural killer (NK) cells, including pro-inflammatory cytokine secretion and cytotoxicity. An immunosuppressive receptor, T-cell immunoglobulin and immunoreceptor tyrosine–based inhibitory motif (ITIM) domain (TIGIT) is specifically expressed in NK cells. This study aims to investigate the role of the TIGIT signaling pathway in regulating NK cell functions in patients with CHB.

Method

We comparatively assessed the expression of TIGIT in NK cells of patients with immune active CHB (CHB-IA), carriers of immune control chronic HBV (CHB-IC), and healthy controls (HCs), and then explored mechanisms of the TIGIT signaling pathway in regulating NK cell-mediated liver injury by different molecular assessments.

Result

The expression of TIGIT in NK cells was enhanced in CHB-IC but was reduced in CHB-IA compared with the HC group. In patients with CHB-IA, the expression of TIGIT was inversely correlated with intensity of the liver damage. Moreover, TIGIT-NK cells show higher IFN-γ secretion capability, degranulation activity, and cytotoxicity but lower apoptosis than TIGIT+ NK cells. Blockade of the TIGIT pathway with anti-TIGIT antibody increased NK cell function, while activation of the TIGIT pathway with TIGIT Fc and CD155 Fc chimera protein down-regulated NK cell function.

Conclusion

Our data showed that the TIGIT signaling pathway participates in NK cell impairment, which could be used as a new therapeutic target to protect patients with chronic HBV infection from severe liver injury.

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.

Long-Term Hepatitis B Virus Infection Induces Cytopathic Effects in Primary Human Hepatocytes, and Can Be Partially Reversed by Antiviral Therapy

Chronic infection of hepatitis B virus (HBV) remains a major health burden worldwide. While the immune response has been recognized to play crucial roles in HBV pathogenesis, the direct cytopathic effects of HBV infection and replication on host hepatocytes and the HBV-host interactions are only partially defined due to limited culture systems. Here, based on our recently developed 5 chemical-cultured primary human hepatocytes (5C-PHHs) model that supports long-term HBV infection, we performed multiplexed quantitative analysis of temporal changes of host proteome and transcriptome on PHHs infected by HBV for up to 4 weeks. We showed that metabolic-, complement-, cytoskeleton-, mitochondrial-, and oxidation-related pathways were modulated at transcriptional or posttranscriptional levels during long-term HBV infection, which led to cytopathic effects and could be partially rescued by early, rather than late, nucleot(s)ide analog (NA) administration and could be significantly relieved by blocking viral antigens with RNA interference (RNAi). Overexpression screening of the dysregulated proteins identified a series of host factors that may contribute to pro- or anti-HBV responses of the infected hepatocytes. In conclusion, our results suggest that long-term HBV infection in primary human hepatocytes leads to cytopathic effects through remodeling the proteome and transcriptome and early antiviral treatment may reduce the extent of such effects, indicating a role of virological factors in HBV pathogenesis and a potential benefit of early administration of antiviral treatment. IMPORTANCE Global temporal quantitative proteomic and transcriptomic analysis using long-term hepatitis B virus (HBV)-infected primary human hepatocytes uncovered extensive remodeling of the host proteome and transcriptome and revealed cytopathic effects of long-term viral replication. Metabolic-, complement-, cytoskeleton-, mitochondrial-, and oxidation-related pathways were modulated at transcriptional or posttranscriptional levels, which could be partially rescued by early, rather than late, NA therapy and could be relieved by blocking viral antigens with RNAi. Overexpression screening identified a series of pro- or anti-HBV host factors. These data have deepened the understanding of the mechanisms of viral pathogenesis and HBV-host interactions in hepatocytes, with implications for therapeutic intervention.

Role of HLA-G in Viral Infections

The human leukocyte antigen (HLA)-G is a non-classical HLA class I molecule, which has distinct features to classical HLA-A, -B, -C antigens, such as a low polymorphism, different splice variants, highly restricted, tightly regulated expression and immune modulatory properties. HLA-G expression in tumor cells and virus-infected cells, as well as the release of soluble HLA-G leads to escape from host immune surveillance. Increased knowledge of the link between HLA-G expression, viral infection and disease progression is urgently required, which highlights the possible use of HLA-G as novel diagnostic and prognostic biomarker for viral infections, but also as therapeutic target. Therefore, this review aims to summarize the expression, regulation, function and impact of HLA-G in the context of different viral infections including virus-associated cancers. The characterization of HLA-G-driven immune escape mechanisms involved in the interactions between host cells and viruses might result in the design of novel immunotherapeutic strategies targeting HLA-G and/or its interaction with its receptors on immune effector cells.