Immune responses and immunopathology in acute and chronic viral hepatitis. Nat Rev Immunol. 2016;16:509-523. [PMID: 27374637 DOI: 10.1038/nri.2016.69]

Many Ways to Communicate-Crosstalk between the HBV-Infected Cell and Its Environment

Chronic infection with the hepatitis B virus (HBV) affects an estimated 257 million people worldwide and can lead to liver diseases such as cirrhosis and liver cancer. Viral replication is generally considered not to be cytopathic, and although some HBV proteins may have direct carcinogenic effects, the majority of HBV infection-related disease is related to chronic inflammation resulting from disrupted antiviral responses and aberrant innate immune reactions. Like all cells, healthy and HBV-infected cells communicate with each other, as well as with other cell types, such as innate and adaptive immune cells. They do so by both interacting directly and by secreting factors into their environment. Such factors may be small molecules, such as metabolites, single viral proteins or host proteins, but can also be more complex, such as virions, protein complexes, and extracellular vesicles. The latter are small, membrane-enclosed vesicles that are exchanged between cells, and have recently gained a lot of attention for their potential to mediate complex communication and their potential for therapeutic repurposing. Here, we review how HBV infection affects the communication between HBV-infected cells and cells in their environment. We discuss the impact of these interactions on viral persistence in chronic infection, as well as their relation to HBV infection-related pathology.

Multifaceted Defects in Monocytes in Different Phases of Chronic Hepatitis B Virus Infection: Lack of Restoration after Antiviral Therapy

Monocytes play an important role in the control of microbial infection, but monocyte biology during chronic hepatitis B virus (HBV) infection (CHI) remains inadequately studied. We investigated the frequency, phenotype, and functions of monocyte subsets in different phases of CHI, namely, immune tolerance (IT), hepatitis B early antigen (HBeAg)-positive/HBeAg-negative chronic hepatitis B (EP-/EN-CHB, respectively), and inactive carrier (IC), identified factors responsible for their functional alterations, and determined the impact of antiviral therapy on these cells. Flow cytometric analysis indicated that HLA-DR⁺ CD14⁺⁺ CD16^- classical monocytes were significantly reduced while HLA-DR⁺ CD14⁺⁺ CD16⁺ intermediate and HLA-DR⁺ CD14⁺ CD16⁺⁺ nonclassical monocytes were expanded in IT and EP-/EN-CHB compared with those in IC and healthy controls (HC). In comparison to IC/HC, monocytes in IT and CHB exhibited diminished expression of Toll-like receptor 2 (TLR-2)/TLR-4/TLR-9 and cytokines interleukin-12 (IL-12)/tumor necrosis factor alpha (TNF-α)/IL-6 but produced higher levels of IL-10/transforming growth factor β (TGF-β). Further, monocytes in CHB/IT showed impaired phagocytosis and oxidative response relative to those in IC/HC. In vitro assays indicated that high titers of hepatitis B surface antigen (HBsAg) present in IT/CHB and of IL-4 in CHB triggered the functional defects in monocytes via induction of β-catenin. Additionally, monocyte-derived M1 macrophages of CHB/IT produced fewer proinflammatory and more anti-inflammatory cytokines than those of IC/HC, while in CHB/IT, the monocytes skewed the differentiation of CD4⁺ T cells more toward regulatory T cells and a Th2 phenotype. Moreover, monocytes in CHB and IT overexpressed chemokine receptor CCR2, which coincided with increased intrahepatic accumulation of β-catenin⁺ CD14⁺ cells. One year of tenofovir therapy failed to normalize monocyte functions or reduce serum HBsAg/IL-4 levels. Taken together, monocytes are functionally perturbed mostly in IT and EP-/EN-CHB phases. Targeting intramonocytic β-catenin or reducing HBsAg/IL-4 levels might restore monocyte function and facilitate viral clearance. IMPORTANCE Chronic HBV infection (CHI) is a major cause of end-stage liver disease for which pharmacological treatments currently available are inadequate. Chronically HBV-infected patients fail to mount an efficient immune response to the virus, impeding viral clearance and recovery from hepatitis. Monocytes represent a central part of innate immunity, but a comprehensive understanding on monocyte involvement in CHI is still lacking. We here report a multitude of defects in monocytes in chronically HBV-infected patients that include alteration in subset distribution, Toll-like receptor expression, cytokine production, phagocytic activity, oxidative response, migratory ability, polarization of monocyte-derived macrophages, and monocyte-T-cell interaction. We demonstrated that high levels of hepatitis B virus surface antigen and IL-4 potentiate these defects in monocytes via β-catenin induction while therapy with the nucleotide analog tenofovir fails to restore monocyte function. Our findings add to the continuing effort to devise new immunotherapeutic strategies that could reverse the immune defects in CHI.

Hepatitis B and C viral coinfections and their association with HIV viral load suppression among HIV-1 infected patients on ART at Mekelle hospital, northern Ethiopia

BACKGROUND

Although Ethiopia is endemic to viral hepatitis and HIV, data that could guide population-specific interventions are limited. In this study, we determined the seroprevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) and assessed their associations with HIV-1 viral load suppression among HIV-1 infected patients on antiretroviral therapy (ART) at Mekelle hospital in northern Ethiopia.

METHODS

Between February and April 2020, blood samples were collected from 439 participants. Samples were screened for HBsAg and anti-HCV on the immunochromatographic test and confirmed using the Enzyme-Linked Immuno-sorbent assay (Beijing Wantai Co. China). HIV-1 viral load was quantified using reverse transcription-polymerase chain reaction (RT-PCR) on the Abbott platform. Binary and multivariable logistic regression was performed to identify potential predictors.

RESULTS

Overall, 10% (44/439) and 3.6% (16/439) of the participants were coinfected with HBV and HCV, respectively. In a multivariate analysis, being illiterate (AOR = 6.57; 95% CI 1.04-41.6), and having a history of sexually transmitted infections (AOR = 4.44; 95% CI 1.31-15.0) and multiple sexual partners (AOR = 29.9; 95% CI 7.82-114.8) were associated with HBV infection. On the other hand, participants with a history of chronic non-communicable diseases (AOR = 10.6, 95% CI 1.61-70.1), and those reporting a history of sexually transmitted infections (AOR = 5.21, 95% CI 1.39-19.5) were more likely to be infected with HCV. In further analysis, HCV infection status was significantly associated with decreased viral load suppression rate (AOR = 7.14; 95% CI 2.18-23.3) whereas no significant association was observed with the HBV infection.

CONCLUSIONS

The HBV coinfection rate in our study is high and, as per WHO's standard, corresponds to a hyperendemic level. The HCV coinfection rate is also substantially high and urges attention given its influence on the viral load suppression of HIV patients on ART at our study site. Our findings suggest the need to adopt universal screening and vaccination of people with HIV against HBV and screening for HCV at our study site and in Ethiopia at large, which contributes to Ethiopia's progress towards the 2030 global target of reducing the HBV infection.

Mesenchymal stem cells-based therapy in liver diseases

Multiple immune cells and their products in the liver together form a complex and unique immune microenvironment, and preclinical models have demonstrated the importance of imbalances in the hepatic immune microenvironment in liver inflammatory diseases and immunocompromised liver diseases. Various immunotherapies have been attempted to modulate the hepatic immune microenvironment for the purpose of treating liver diseases. Mesenchymal stem cells (MSCs) have a comprehensive and plastic immunomodulatory capacity. On the one hand, they have been tried for the treatment of inflammatory liver diseases because of their excellent immunosuppressive capacity; On the other hand, MSCs have immune-enhancing properties in immunocompromised settings and can be modified into cellular carriers for targeted transport of immune enhancers by genetic modification, physical and chemical loading, and thus they are also used in the treatment of immunocompromised liver diseases such as chronic viral infections and hepatocellular carcinoma. In this review, we discuss the immunological basis and recent strategies of MSCs for the treatment of the aforementioned liver diseases. Specifically, we update the immune microenvironment of the liver and summarize the distinct mechanisms of immune microenvironment imbalance in inflammatory diseases and immunocompromised liver diseases, and how MSCs can fully exploit their immunotherapeutic role in liver diseases with both immune imbalance patterns.

Identification of a distinct NK-like hepatic T-cell population activated by NKG2C in a TCR-independent manner

BACKGROUND & AIMS

The liver provides a unique niche of lymphocytes enriched with a large proportion of innate-like T cells. However, the heterogeneity and functional characteristics of the hepatic T-cell population remain to be fully elucidated.

METHODS

We obtained liver sinusoidal mononuclear cells from the liver perfusate of healthy donors and recipients with HBV-associated chronic liver disease (CLD) during liver transplantation. We performed a CITE-seq analysis of liver sinusoidal CD45⁺ cells in combination with T cell receptor (TCR)-seq and flow cytometry to examine the phenotypes and functions of liver sinusoidal CD8⁺ T cells.

RESULTS

We identified a distinct CD56^hiCD161^-CD8⁺ T-cell population characterized by natural killer (NK)-related gene expression and a uniquely restricted TCR repertoire. The frequency of these cells among the liver sinusoidal CD8⁺ T-cell population was significantly increased in patients with HBV-associated CLD. Although CD56^hiCD161^-CD8⁺ T cells exhibit weak responsiveness to TCR stimulation, CD56^hiCD161^-CD8⁺ T cells highly expressed various NK receptors, including CD94, killer immunoglobulin-like receptors, and NKG2C, and exerted NKG2C-mediated NK-like effector functions even in the absence of TCR stimulation. In addition, CD56^hiCD161^-CD8⁺ T cells highly respond to innate cytokines, such as IL-12/18 and IL-15, in the absence of TCR stimulation. We validated the results from liver sinusoidal CD8⁺ T cells using intrahepatic CD8⁺ T cells obtained from liver tissues.

CONCLUSIONS

In summary, the current study found a distinct CD56^hiCD161^-CD8⁺ T-cell population characterized by NK-like activation via TCR-independent NKG2C ligation. Further studies are required to elucidate the roles of liver sinusoidal CD56^hiCD161^-CD8⁺ T cells in immune responses to microbial pathogens or liver immunopathology.

LAY SUMMARY

The role of different immune cell populations in the liver is becoming an area of increasing interest. Herein, we identified a distinct T-cell population that had features similar to those of natural killer (NK) cells - a type of innate immune cell. This distinct population was expanded in the livers of patients with chronic liver disease and could thus have pathogenic relevance.

Hepatitis Viruses Control Host Immune Responses by Modifying the Exosomal Biogenesis Pathway and Cargo

The development of smart immune evasion mechanisms is crucial for the establishment of acute and chronic viral hepatitis. Hepatitis is a major health problem worldwide arising from different causes, such as pathogens, metabolic disorders, and xenotoxins, with the five hepatitis viruses A, B, C, D, and E (HAV, HBV, HCV, HDV, and HEV) representing the majority of the cases. Most of the hepatitis viruses are considered enveloped. Recently, it was reported that the non-enveloped HAV and HEV are, in reality, quasi-enveloped viruses exploiting exosomal-like biogenesis mechanisms for budding. Regardless, all hepatitis viruses use exosomes to egress, regulate, and eventually escape from the host immune system, revealing another key function of exosomes apart from their recognised role in intercellular communication. This review will discuss how the hepatitis viruses exploit exosome biogenesis and transport capacity to establish successful infection and spread. Then, we will outline the contribution of exosomes in viral persistence and liver disease progression.

Lack of Association of Polymorphisms in IL22 and IL22RA1 Genes with Fibrosis Severity in Patients with Chronic Hepatitis C

The IL-22 pathway has been shown to play an important role in the pathogenesis of liver fibrosis. However, little is known about the role of single-nucleotide polymorphisms (SNPs) in IL-22-related genes in relation to the severity of liver fibrosis. This study aimed to investigate the association of polymorphisms in IL22 and IL22RA1 genes with the severity of liver fibrosis in patients with chronic hepatitis C. A total of 326 patients (165 with mild fibrosis and 161 with severe fibrosis) were included. Four SNPs in IL22 (rs1179251, rs2227473, rs1012356, and rs2227485) and two in IL22RA1 (rs4648936 and rs3795299) were evaluated by real-time PCR. No significant association was observed between the polymorphisms studied and the severity of liver fibrosis. The SNPs rs1179251, rs2227473, rs1012356, and rs2227485 in IL22 and rs4648936 and rs3795299 in IL22RA1 may not be involved in the pathogenesis of liver fibrosis in patients with chronic hepatitis C.

DNA Damage Repair Classifier Defines Distinct Groups in Hepatocellular Carcinoma

Simple Summary

DNA repair pathways have been implicated in hepatocellular carcinoma outcomes. We found that hepatocellular carcinomas (HCC) could be separated into two groups (high and low) based on the overall expression of genes involved in DNA repair. Among the low repair group, there were three subgroups, one of which shared features of the high repair group. Given the important role of liver in metabolism and detoxification and its regenerative capacity, proliferation and DNA damage responses are critical in subdividing major biological categories of liver tumors. High repair samples showed more proliferative and regenerative signatures and had poorer outcomes versus the low repair that were more associated with the genes involved in normal liver biology. These biological groups suggest that dysregulation in endogenous liver processes promotes a pro-tumorigenic microenvironment that may facilitate tumor progression or identify tumors that require more substantial clinical intervention.

Abstract

DNA repair pathways have been associated with variability in hepatocellular carcinoma (HCC) clinical outcomes, but the mechanism through which DNA repair varies as a function of liver regeneration and other HCC characteristics is poorly understood. We curated a panel of 199 genes representing 15 DNA repair pathways to identify DNA repair expression classes and evaluate their associations with liver features and clinicopathologic variables in The Cancer Genome Atlas (TCGA) HCC study. We identified two groups in HCC, defined by low or high expression across all DNA repair pathways. The low-repair group had lower grade and retained the expression of classical liver markers, whereas the high-repair group had more clinically aggressive features, increased p53 mutant-like gene expression, and high liver regenerative gene expression. These pronounced features overshadowed the variation in the low-repair subset, but when considered separately, the low-repair samples included three subgroups: L1, L2, and L3. L3 had high DNA repair expression with worse progression-free (HR 1.24, 95% CI 0.81–1.91) and overall (HR 1.63, 95% CI 0.98–2.71) survival. High-repair outcomes were also significantly worse compared with the L1 and L2 groups. HCCs vary in DNA repair expression, and a subset of tumors with high regeneration profoundly disrupts liver biology and poor prognosis.

Echovirus 11 infection induces pyroptotic cell death by facilitating NLRP3 inflammasome activation

Echovirus 11 (ECHO 11) is a positive-strand RNA virus belonging to the genus Enterovirus of the family Picornaviridae. ECHO 11 infections can cause severe inflammatory illnesses in neonates, including severe acute hepatitis with coagulopathy. The activation of NLRP3 inflammasome is important for host defense against invading viruses, which also contributes to viral pathogenicity. However, whether and how ECHO 11 induces NLRP3 inflammasome activation remains unclear. In this study, we isolated a clinical strain of ECHO 11 from stools of an ECHO 11-infected newborn patient with necrotizing hepatitis. This virus shared 99.95% sequence identity with the previously published ECHO 11 sequence. The clinically isolated ECHO 11 can efficiently infect liver cells and strongly induces inflammation. Moreover, we showed that ECHO 11 induced IL-1β secretion and pyroptosis in cells and mouse bone marrow-derived macrophages (BMDMs). Furthermore, ECHO 11 infection triggered NLRP3 inflammasome activation, as evidenced by cleavages of GSDMD, pro-IL-1β and pro-caspase-1, and the release of LDH. ECHO 11 2B protein was required for NLRP3 inflammasome activation via interacting with NLRP3 to facilitate the inflammasome complex assembly. In vivo, expression of ECHO 11 2B also activated NLRP3 inflammasome in the murine liver. Besides, 2Bs of multiple EVs can also interact with NLRP3 and induce NLRP3 inflammasome activation. Together, our findings demonstrate a mechanism by which ECHO 11 induces inflammatory responses by activating NLRP3 inflammasome, providing novel insights into the pathogenesis of ECHO 11 infection.

NLRP3 inflammasome is important for host defense against invading viruses, and contributes to viral pathogenicity. Human echovirus 11 (ECHO 11) belongs to the Enterovirus genus from the family Picornavirida, and it can cause severe acute hepatitis in newborns with high morbidity and mortality. However, the knowledge about the pathogenesis of ECHO 11 infection is limited. Whether and how ECHO 11 induces NLRP3 inflammasome activation remains unclear. This work provides the first demonstration that ECHO 11 can induce inflammatory responses via activating NLRP3 inflammasome and pyroptosis. More importantly, ECHO 11-encoded 2B protein was found to activate NLRP3 inflammasome in cells and in vivo, and the interaction between 2B and NLRP3 was required for inflammasome complex assembly. Furthermore, we uncovered that 2Bs of other enteroviruses, including enterovirus 71, coxsackievirus A16 (CVA16) and CVB3 could induce NLRP3 inflammasome and interact with NLRP3. Our findings uncover a mechanism by which ECHO 11 induces inflammatory responses and demonstrate a novel function of ECHO 11 2B.

Connexin-Based Channels in the Liver

Connexin proteins oligomerize in hexameric structures called connexin hemichannels, which then dock to form gap junctions. Gap junctions direct cell-cell communication by allowing the exchange of small molecules and ions between neighboring cells. In this way, hepatic gap junctions support liver homeostasis. Besides serving as building blocks for gap junctions, connexin hemichannels provide a pathway between the intracellular and the extracellular environment. The activation of connexin hemichannels is associated with acute and chronic liver pathologies. This article discusses the role of gap junctions and connexin hemichannels in the liver. © 2022 American Physiological Society. Compr Physiol 12:1-17, 2022.

Analyzing the gene regulatory network in hepatitis B patients by single-cell ATAC sequencing

OBJECTIVE

This study aims to provide a new perspective of determining the pathophysiology of chronic hepatitis B (CHB) development by analyzing the gene regulatory network in CHB patients using single-cell ATAC sequencing.

BACKGROUND

Hepatitis B virus (HBV)-related liver disease induces liver damage by hepatic immune and inflammatory responses. The exact mechanism is unknown. As such, there is an urgent need to address this problem and study the relationship between aberrant peripheral blood mononuclear cell (PBMC) immune response and progression of liver disease.

METHOD

The sequencing of the chromatin accessibility of 8016 cells from the whole venous blood of normal control (NC) individuals and CHB patients was performed through assay for transposase-accessible chromatin in single-cell sequencing (ScATAC-seq). Unsupervised clustering and annotation analyses were performed by Signac (version 1.7.0) and Seurat clustering to identify different cell types. Then, TF motif enrichment analysis and differentially expressed peak analysis were performed to identify cell-type-specific candidate open chromatins related to CHB.

RESULT

We identified 12 leukocytic clusters corresponding to five cell types. The specific cell types associated with CHB were found to be located in B-0 and T-3. We have drawn the regulatory network of the hepatitis B signal pathway composed of genes linked to the differentially expressed peaks of these two CHB disease-specific cell types. Further, we profoundly explored the potential mechanisms of B-0-associated TF motif IRF2 and T-3-associated TF motif FOXC2 in the occurrence of CHB.

CONCLUSION

We have drawn a systematic and distinguishing gene regulatory network of CHB-related PBMCs. Key Points • Peripheral blood mononuclear cells were robustly clustered based on their types without using antibodies. • We draw a systematic and distinctive gene regulatory network of CHB-related PBMC through ScATAC-seq.

Arthrospira Enhances Seroclearance in Patients with Chronic Hepatitis B Receiving Nucleos(t)ide Analogue through Modulation of TNF-α/IFN-γ Profile

Chronic hepatitis B (CHB) virus infection, causing immune dysfunction and chronic hepatitis, is one of the leading risk factors for hepatocellular cancer. We investigated how Arthrospira affected hepatitis B surface antigen (HBsAg) reduction in CHB patients under continued nucleos(t)ide analogues (NA). Sixty CHB patients who had been receiving NA for at least one year with undetectable HBV DNA were randomized into three groups: control and oral Arthrospira at 3 or 6 g daily add-on therapy groups. Patients were followed up for 6 months. Oral Arthrospira-diet mice were established to investigate the possible immunological mechanism of Arthrospira against HBV. Within 6 months, mean quantitative HBsAg (qHBsAg) decreased in the oral Arthrospira add-on therapy group. Interestingly, interferon gamma (IFN-γ) increased but TNF-α, interleukin 6 (IL-6), hepatic fibrosis, and steatosis decreased in the add-on groups. In mice, Arthrospira enhanced both innate and adaptive immune system, especially natural killer (NK) cell cytotoxicity, B cell activation, and the interleukin 2 (IL-2), IFN-γ immune response. Arthrospira may modulate IL-2- and TNF-α/IFN-γ-mediated B and T cell activation to reduce HBsAg. Also, Arthrospira has the potential to restore immune tolerance and enhance HBsAg seroclearance in CHB patients through promoting T, B, and NK cell activation.

Occult hepatitis B — the result of the host immune response interaction with different genomic expressions of the virus

With over 40 years of history, occult hepatitis B infection (OBI) continues to remain an important and challenging public health problem. Defined as the presence of replication-competent hepatitis B virus (HBV) DNA (i.e., episomal HBV covalently closed circular DNA) in the liver and/or HBV DNA in the blood of people who test negative for hepatitis B surface antigen (HBsAg) in currently available assays, OBI is currently diagnosed using polymerase chain reaction (PCR) and real-time PCR assays. However, all efforts should be made to exclude a false negative HBsAg in order to completely follow the definition of OBI. In recent years, significant advances have been made in understanding the HBV lifecycle and the molecular mechanisms that lead to the persistence of the virus in the occult form. These factors are mainly related to the host immune system and, to a smaller proportion, to the virus. Both innate and adaptive immune responses are important in HBV infection management, and epigenetic changes driven by host mechanisms (acetylation, methylation, and microRNA implication) are added to such actions. Although greater genetic variability in the S gene of HBV isolated from OBIs was found compared with overt infection, the mechanisms of OBI are not mainly viral mutations.

Negative impact of HIV infection on broad-spectrum anti-HCV neutralizing antibody titers in HCV-infected patients with advanced HCV-related cirrhosis

OBJECTIVES

The current study aimed to assess the impact of HIV on the production of anti-HCV antibodies in HCV-infected individuals with advanced HCV-related cirrhosis before and 36 weeks after the sustained virological response (SVR) induced by direct-acting antivirals (DAAs) therapy.

METHODS

Prospective study on 62 patients (50 HIV/HCV-coinfected and 12 HCV-monoinfected). Plasma anti-E2 and HCV-nAbs were determined respectively by ELISA and microneutralization assays.

RESULTS

At baseline, the HCV-group had higher anti-E2 levels against Gt1a (p = 0.012), Gt1b (p = 0.023), and Gt4a (p = 0.005) than the HIV/HCV-group. After SVR, anti-E2 titers against Gt1a (p < 0.001), Gt1b (p = 0.001), and Gt4a (p = 0.042) were also higher in the HCV-group than HIV/HCV-group. At 36 weeks post-SVR, plasma anti-E2 titers decreased between 1.3 and 1.9-fold in the HIV/HCV-group (p < 0.001) and between 1.5 and 1.8-fold in the HCV-group (p ≤ 0.001). At baseline, the HCV-group had higher titers of HCV-nAbs against Gt1a (p = 0.022), Gt1b (p = 0.002), Gt2a (p < 0.001), and Gt4a (p < 0.001) than the HIV/HCV-group. After SVR, HCV-nAbs titers against Gt1a (p = 0.014), Gt1b (p < 0.001), Gt2a (p = 0.002), and Gt4a (p = 0.004) were also higher in the HCV-group. At 36 weeks post-SVR, HCV-nAbs decreased between 2.6 and 4.1-fold in the HIV/HCV-group (p < 0.001) and between 1.9 and 4.0-fold in the HCV-group (p ≤ 0.001).

CONCLUSIONS

HIV/HCV-coinfected patients produced lower levels of broad-spectrum anti-HCV antibodies than HCV-monoinfected patients.

Production and immunogenicity of different prophylactic vaccines for hepatitis C virus (Review)

Hepatitis C virus (HCV) infection is a global health challenge, and prophylactic vaccines are the most effective way to eliminate the infection. To date, numerous forms of preventive vaccines have entered the clinical trial stage, including the virus-like particle (VLP) vaccine, recombinant subunit vaccine, peptide vaccine and nucleic acid vaccine. The rational design makes it easier to obtain specific vaccine structures with a broad spectrum and strong immunogenicity. Different vaccine antigens can evoke different immune responses, including humoral and T-cell immune responses, and can be produced using different expression systems, such as bacteria, yeast, mammals, plants, insects or parasites. Intracellular and insoluble production and a narrow immune spectrum are two difficulties that limit the application of vaccines. The present study summarizes the immunogenicity of different preventive vaccines, evaluates the characteristics of different expression systems used for vaccine production, and analyzes the strategies to enhance the secretion and immune spectrum of vaccine proteins.

Comparison of Immune Responses Elicited by SARS-CoV-2 mRNA and Recombinant Protein Vaccine Candidates

After the outbreak of COVID-19, billions of vaccines with different types have been administrated, including recombinant protein vaccines and mRNA vaccines. Although both types of SARS-CoV-2 vaccine can protect people from viral infection, their differences in humoral and cellular immune responses are still not clearly understood. In this study, we made a head-to-head comparison between an mRNA vaccine candidate and a recombinant protein vaccine we developed previously. Results demonstrated that both vaccine candidates could elicit high specific binding and neutralizing antibody titers in BALB/c mice, but with bias towards different IgG subtypes. Besides, the mRNA vaccine candidate induces higher cellular immune responses than the recombinant protein vaccine. To date, this is the first reported study to directly compare the immune responses of both arms between SARS-CoV-2 mRNA and recombinant vaccines.

Experimental cross-species infection of donkeys with equine hepacivirus and analysis of host immune signatures

BACKGROUND

The Equine Hepacivirus (EqHV) is an equine-specific and liver-tropic virus belonging to the diverse genus of Hepaciviruses. It was recently found in a large donkey (Equus asinus) cohort with a similar seroprevalence (30%), but lower rate of RNA-positive animals (0.3%) compared to horses. These rare infection events indicate either a lack of adaptation to the new host or a predominantly acute course of infection.

METHODS

In order to analyze the susceptibility and the course of EqHV infection in donkeys, we inoculated two adult female donkeys and one control horse intravenously with purified EqHV from a naturally infected horse. Liver biopsies were taken before and after inoculation to study changes in the transcriptome.

RESULTS

Infection kinetics were similar between the equids. All animals were EqHV PCR-positive from day three. EqHV RNA-levels declined when the animals seroconverted and both donkeys cleared the virus from the blood by week 12. Infection did not have an impact on the clinical findings and no significant histopathological differences were seen. Blood biochemistry revealed a mild increase in GLDH at the time of seroconversion in horses, which was less pronounced in donkeys. Transcriptomic analysis revealed a distinct set of differentially expressed genes, including viral host factors and immune genes.

CONCLUSION

To summarize, our findings indicate that donkeys are a natural host of EqHV, due to the almost identical infection kinetics. The different immune responses do however suggest different mechanisms in reacting to hepaciviral infections.

Liver Immunology, Immunotherapy, and Liver Cancers: Time for a Rethink?

The complex immune system of the liver has a major role in tumor surveillance, but also partly explains why current immune therapies are poorly effective against liver cancers. Known primarily for its tolerogenic capacity, the hepatic immune repertoire also comprises diverse populations of armored immune cells with tumor surveillant roles. In healthy people, these work together to successfully identify malignant cells and prevent their proliferation, thus halting tumor formation. When frontline hepatic immune surveillance systems fail, compromised hepatic immunity, driven by obesity, infection, or other pathological factors, allows primary or secondary liver cancers to develop. Tumor growth promotes the normal tolerogenic immunological milieu of the liver, perhaps explaining why current immunotherapies fail to work. This review explores the complex local liver immune system with the hope of identifying potential therapeutic targets needed to best overcome immunological barriers in the liver to create an environment no longer hostile to immunotherapy for the treatment of liver cancer.

Genetic associations in chronic hepatitis B infection: toward developing polygenic risk scores

Chronic hepatitis B (CHB) infection results in multiple clinical phenotypes of varying severity. One of the critical gaps in CHB management is the lack of a genetic-based tool to aid existing hepatocellular carcinoma and cirrhosis risk stratification models for patients with active CHB. Such individual predictive models for CHB are plagued by an inherent limitation of discriminatory power that clearly indicates the need for their improvement. In this article, we highlight genetic association studies in CHB that identified HLA and cytokine genetic susceptibility loci to CHB. We advance the position that translating CHB genetic susceptibility loci into polygenic risk scores will be a welcome addendum to the current arsenal of CHB outcome predictive models. We conclude with comments on hurdles that future research efforts should address within the research enclave of CHB and advocate for increased genetic data representation from sub-Saharan Africa.

Periodontitis, chronic liver diseases, and the emerging oral-gut-liver axis

The liver carries out a wide range of functions ranging from the control of metabolites, nutrient storage, and detoxification to immunosurveillance. While inflammation is essential for the tissue remodeling and maintenance of homeostasis and normal liver physiology, constant exposure to dietary and microbial products creates a niche for potentially prolonged immune activation and unresolved inflammation in susceptible host. Failure to restrain inflammation can lead to development of chronic liver diseases characterized by fibrosis, cirrhosis and eventually liver failure. The liver maintains close interactions with numerous organs which can influence its metabolism and physiology. It is also known that oral cavity microenvironment can influence the physiological conditions of other organs and emerging evidence implicates that this could be true for the liver as well. Presence of chronic inflammation and dysbiotic microbiota is a common feature leading to clinical pathology both in periodontitis and chronic liver diseases (CLDs). In fact, known CLDs appear to have some relationship with periodontitis, which impacts the onset or progression of these conditions in a bidirectional crosstalk. In this review, we explore the emerging association between oral‐gut‐liver axis focusing on periodontitis and common CLDs including nonalcoholic fatty liver disease, chronic viral hepatitis, liver cirrhosis, and hepatocellular cancer. We highlight the immune pathways and oral microbiome interactions which can link oral cavity and liver health and offer perspectives for future research.

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.

Types of Interferons and Their Expression in Plant Systems

Interferons (IFNs) are divided into 3 types (type I, type II, and type III) on the basis of sequence homology and functional properties. Recombinant IFNs have been approved by regulatory agencies in many countries for clinical treatment of hepatitis B, hepatitis C, and other diseases; these IFNs are mainly produced in microorganisms and mammalian cell systems. However, there are serious obstacles to the production of recombinant IFNs in microorganism systems; for example, the recombinant IFN may have different glycosylation patterns from the native protein, be present in insoluble inclusion bodies, be contaminated with impurities such as endotoxins and nucleic acids, have a short half-life in human blood, and incur high production costs. Some medicinal proteins have been successfully expressed in plants and used in clinical applications, suggesting that plants may also be a good system for IFN expression. However, there are still many technical problems that need to be addressed before the clinical application of plant-expressed IFNs, such as increasing the amount of recombinant protein expression and ensuring that the IFN is modified with the correct type of glycosylation. In this article, we review the classification of IFNs, their roles in antiviral signal transduction pathways, their clinical applications, and their expression in plant systems.

[Safety of blood and blood products: test methods for the detection of hepatitis B, C, and E virus]

Infections with hepatitis B, C, and E virus (HBV, HCV, and HEV) can be transmitted via blood and cause severe acute or chronic liver infections. To ensure the safety of blood donations and protect recipients from virus transmissions, blood donations in Germany are tested for viral genomes using nucleic acid amplification techniques (NATs) as well as for viral antigens and antibodies by serological testing. This article describes the relevant regulations on the safety of blood and blood products in Germany and the various screening methods. The safety of blood products is assessed.Currently used NAT methods for detection of hepatitis viruses are based either on polymerase chain reaction (PCR) or isothermal methods such as transcription-mediated amplification (TMA), which enable a highly sensitive detection of viral infections and thereby contribute to the reduction of the diagnostic window. Antigen tests for the detection of viral surface protein of hepatitis B virus in blood donations were introduced in the 1970s in order to prevent potential transmissions. Since the introduction of mandatory testing for HCV-specific antibodies in 1992, HCV NAT testing in 1999, anti-HBc antibody testing in 2006, and the non-mandatory HBV NAT, which is voluntarily performed by most of the blood establishments, blood safety has increased tremendously. Only a few isolated cases of transfusion-transmitted infections in the early window period have been reported since. The success of the recent introduction of mandatory HEV NAT testing in 2020 will have to be assessed in the upcoming years. Besides blood donor screening, the system for blood safety in Germany is supplemented by additional measures for donor selection and pathogen inactivation.

Intrahepatic immune infiltrate in chronic hepatitis B and chronic hepatitis C: Similar but not the same

In chronic hepatitis B (CHB) and C (CHC) infections, the composition of the immune cell microenvironment at the site of infection is poorly understood. Thus, our aim was to characterize and compare liver infiltrates to identify shared and exclusive hepatic immune components. Immunohistochemistry was performed on 26 CHB and 42 CHC liver biopsies to determine Th (CD4+), Th1 (T-bet+), Th17 (IL-17A+), Treg (Foxp3+) and CTL (CD8+) cells frequency in portal/periportal and intralobular areas and relate them to liver damage. CHB and CHC cases shared a portal/periportal CD4+ lymphocyte predominance and a lobular CD8+ lymphocyte majority. However, CHC exhibited a concomitant lobular T-bet+ cell dominance while in CHB FoxP3+ cells prevail. CHC disclosed higher frequencies of P/P FoxP3+, IL-17A+ and T-bet+ cells and intralobular CD4+, IL-17A+ and T-bet+ lymphocytes. HBeAg+ chronic hepatitis and CHC cell frequencies were similar except for lobular T-bet+ that remained higher among CHC cases. Comparison among cases with less severe liver disease revealed lower lymphocyte frequencies in CHB samples, while no differences were observed between patients with more severe stages. Interestingly, in CHB portal/periportal CD4+ and lobular CD4+, CD8+ and IL-17A+ cells were associated with severe hepatitis. Even when all studied populations were identified in both infections preferential lymphocyte frequencies and prevalence at different areas along with their association with liver damage highlighted that CHB and CHC immune responses are not the same.

Risk of hepatocellular carcinoma after hepatitis C virus cure

Hepatitis C virus (HCV) is a significant cause of hepatocellular carcinoma (HCC). The direct-acting antivirals marked a new era of HCV therapy and are associated with greater than 95% cure rate. Successful treatment of chronic hepatitis C greatly reduces the risk of HCC. A proportion of patients, especially those with pre-existing cirrhosis, remain at risk for HCC despite sustained virologic response (SVR). Diabetes mellitus, hepatic steatosis, alcohol consumption and lack of fibrosis regression are associated with risks of HCC after HCV cure. Noninvasive modalities such as aspartate aminotransferase to platelet ratio index and fibrosis-4 index and transient elastography have been used to monitor hepatic fibrosis. More recently, various fibrosis scores have been combined with clinical parameters and other novel biomarkers to predict risks of HCC for patients who achieved SVR. These models still need to be validated and standardized prior to applying to routine clinical care.

Significance of bystander T cell activation in microbial infection

During microbial infection, pre-existing memory CD8⁺ T cells that are not specific for the infecting pathogens can be activated by cytokines without cognate antigens, termed bystander activation. Studies in mouse models and human patients demonstrate bystander activation of memory CD8⁺ T cells, which exerts either protective or detrimental effects on the host, depending on the infection model or disease. Research has elucidated mechanisms underlying the bystander activation of CD8⁺ T cells in terms of the responsible cytokines and the effector mechanisms of bystander-activated CD8⁺ T cells. In this Review, we describe the history of research on bystander CD8⁺ T cell activation as well as evidence of bystander activation. We also discuss the mechanisms and immunopathological roles of bystander activation in various microbial infections.

Macrophage Polarization and Its Role in Liver Disease

Macrophages are important immune cells in innate immunity, and have remarkable heterogeneity and polarization. Under pathological conditions, in addition to the resident macrophages, other macrophages are also recruited to the diseased tissues, and polarize to various phenotypes (mainly M1 and M2) under the stimulation of various factors in the microenvironment, thus playing different roles and functions. Liver diseases are hepatic pathological changes caused by a variety of pathogenic factors (viruses, alcohol, drugs, etc.), including acute liver injury, viral hepatitis, alcoholic liver disease, metabolic-associated fatty liver disease, liver fibrosis, and hepatocellular carcinoma. Recent studies have shown that macrophage polarization plays an important role in the initiation and development of liver diseases. However, because both macrophage polarization and the pathogenesis of liver diseases are complex, the role and mechanism of macrophage polarization in liver diseases need to be further clarified. Therefore, the origin of hepatic macrophages, and the phenotypes and mechanisms of macrophage polarization are reviewed first in this paper. It is found that macrophage polarization involves several molecular mechanisms, mainly including TLR4/NF-κB, JAK/STATs, TGF-β/Smads, PPARγ, Notch, and miRNA signaling pathways. In addition, this paper also expounds the role and mechanism of macrophage polarization in various liver diseases, which aims to provide references for further research of macrophage polarization in liver diseases, contributing to the therapeutic strategy of ameliorating liver diseases by modulating macrophage polarization.

Hepatitis C Virus Core Protein Down-Regulates Expression of Src-Homology 2 Domain Containing Protein Tyrosine Phosphatase by Modulating Promoter DNA Methylation

Hepatitis C virus (HCV) is the major causative pathogen associated with liver cirrhosis and hepatocellular carcinoma. The main virion component, the core (C) protein, has been implicated in several aspects of HCV pathology including oncogenesis and immune subversion. Here we show that expression of the C protein induced specific tyrosine phosphorylation of the TCR-related signaling proteins ZAP-70, LAT and PLC-γ in the T cells. Stable expression of the C protein specifically reduced Src homology domain 2-containing protein tyrosine phosphatase 1 (SHP-1) mRNA and protein accumulation. Quantitative CpG methylation analysis revealed a distinct CpG methylation pattern at the SHP-1 gene promoter in the C protein expressing cells that included specific hypermethylation of the binding site for Sp1 transcription factor. Collectively, our results suggest that HCV may suppress immune responses and facilitate its own persistence by deregulating phosphotyrosine signaling via repressive epigenetic CpG modification at the SHP-1 promoter in the T cells.

Blood Levels of Glutamine and Nitrotyrosine in Patients with Chronic Viral Hepatitis

Purpose

Oxidative stress is involved in pathogenesis of chronic viral hepatitis. Glutamine is an antioxidant, but there is a controversy about its risk-benefits. Nitrotyrosine is an oxidative stress marker. This observational cross-sectional study was designed to compare blood levels of glutamine and nitrotyrosine in treated versus untreated chronic viral hepatitis patients.

Patients and Methods

Five groups (n = 250) were included: hepatitis B untreated (HBV), hepatitis C untreated (HCV), HBV treated (HBVT), and HCV treated (HCVT) groups plus a normal control group. Liver function tests and blood levels of glutamine, nitrotyrosine, viral loads, and HBsAg were measured.

Results

Blood levels of glutamine and nitrotyrosine in all patient groups significantly increased compared with normal controls with non-significant differences in-between. Both tests showed significant large correlations with HBV-DNA or HCV-RNA test positivity, high accuracies, and cutoff scores with high sensitivities and specificities. The viral loads and HBsAg levels were significantly lower in treated versus untreated groups. However, they poorly correlated with levels of glutamine and nitrotyrosine in all patient groups.

Conclusion

Blood levels of glutamine and nitrotyrosine significantly increased in treated and untreated chronic viral hepatitis B and C patients compared with normal controls. Both tests showed high accuracies and cutoff scores with high sensitivities and specificities. However, they did not differ significantly in treated versus untreated patients. To our knowledge, this is the first data showing elevation of glutamine and nitrotyrosine in treated and untreated chronic viral hepatitis. A prospective longitudinal study with repeated measurements of glutamine and nitrotyrosine is recommended to verify if they can predict response to treatment. Study of other oxidative stress markers is also advised to clarify if the elevated nitrotyrosine could be an oxidative stress marker in these patients, and whether the increased glutamine could act as an antioxidant or as a predictive agent for deleterious consequences.

T cells protect against hepatitis A virus infection and limit infection-induced liver injury

BACKGROUND & AIMS

Hepatitis A virus (HAV) is a common cause of enterically transmitted viral hepatitis. In non-immune individuals, infection results in typically transient but occasionally fulminant and fatal inflammatory liver injury. Virus-specific T cell frequencies peak when liver damage is at its zenith, leading to the prevalent notion that T cells exacerbate liver disease, as suspected for other hepatotropic virus infections. However, the overall contribution of T cells to the control of HAV and the pathogenesis of hepatitis A is unclear and has been impeded by a historic lack of small animal models.

METHODS

Ifnar1^-/- mice are highly permissive for HAV and develop pathogenesis that recapitulates many features of hepatitis A. Using this model, we identified HAV-specific CD8+ and CD4+ T cells by epitope mapping, and then used tetramers and functional assays to quantify T cells in the liver at multiple times after infection. We assessed the relationships between HAV-specific T cell frequency, viral RNA amounts, and liver pathogenesis.

RESULTS

A large population of virus-specific T cells accumulated within the livers of Ifnar1^-/- mice during the first 1-2 weeks of infection and persisted over time. HAV replication was enhanced and liver disease exacerbated when mice were depleted of T cells. Conversely, immunization with a peptide vaccine increased virus-specific CD8+ T cell frequencies in the liver, reduced viral RNA abundance, and lessened liver injury.

CONCLUSION

These data show that T cells protect against HAV-mediated liver injury and can be targeted to improve liver health.

LAY SUMMARY

Hepatitis A virus is a leading cause of acute viral hepatitis worldwide. T cells were thought to contribute to liver injury during acute infection. We now show that virus-specific T cells protect against infection and limit liver injury.

COVID-19, what could sepsis, severe acute pancreatitis, gender differences, and aging teach us?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a potentially life-threatening disease, defined as Coronavirus Disease 19 (COVID-19). The most common signs and symptoms of this pathological condition include cough, fever, shortness of breath, and sudden onset of anosmia, ageusia, or dysgeusia. The course of COVID-19 is mild or moderate in more than 80% of cases, but it is severe or critical in about 14% and 5% of infected subjects respectively, with a significant risk of mortality. SARS-CoV-2 related infection is characterized by some pathogenetic events, resembling those detectable in other pathological conditions, such as sepsis and severe acute pancreatitis. All these syndromes are characterized by some similar features, including the coexistence of an exuberant inflammatory- as well as an anti-inflammatory-response with immune depression. Based on current knowledge concerning the onset and the development of acute pancreatitis and sepsis, we have considered these syndromes as a very interesting paradigm for improving our understanding of pathogenetic events detectable in patients with COVID-19. The aim of our review is: 1)to examine the pathogenetic mechanisms acting during the emergence of inflammatory and anti-inflammatory processes in human pathology; 2)to examine inflammatory and anti-inflammatory events in sepsis, acute pancreatitis, and SARS-CoV-2 infection and clinical manifestations detectable in patients suffering from these syndromes also according to the age and gender of these individuals; as well as to analyze the possible common and different features among these pathological conditions; 3)to obtain insights into our knowledge concerning COVID-19 pathogenesis. This approach may improve the management of patients suffering from this disease and it may suggest more effective diagnostic approaches and schedules of therapy, depending on the different phases and/or on the severity of SARS-CoV-2 infection.

The Genetic Profile and Serum Level of IL-8 Are Associated with Chronic Hepatitis B and C Virus Infection

The present study evaluated the IL8-251 A/T polymorphism in samples from 74 patients with chronic hepatitis B (HBV), 100 patients with chronic hepatitis C (HCV), and 300 healthy donors (CG). The correlations of this polymorphism with plasma IL-8 and disease stage were calculated. Polymorphisms were identified by real-time PCR. IL-8 was measured by enzyme-linked immunosorbent assay. The IL8-251 A/T genotype was not associated with susceptibility to infection by HBV or HCV. The wild-type allele (A) was associated with higher levels of inflammation (p = 0.0464) and fibrosis scores (p = 0.0016) in the HBV group, representing an increased risk for increased inflammatory activity (OR = 1.84; p = 0.0464) and for high fibrosis scores (OR = 2.63; p = 0.0016). Viral load was higher in HBV patients with polymorphic genotypes (TA and TT) at the IL8-251 A/T polymorphism than in those with the wild-type genotype (p = 0.0272 and p = 0.0464, respectively). Plasma IL-8 was higher among patients infected with HBV or HCV than in the control group (p = 0.0445 and p = 0.0001, respectively). The polymorphic genotype was associated with lower IL-8 than the wild-type genotype in the HBV group (p = 0.0239) and the HCV group (p = 0.0372). The wild-type genotype for IL8-251 A/T and high IL-8 were associated with a worse prognosis for infections; therefore, they may contribute to viral persistence and the development of more severe forms of chronic viral liver diseases.

Baseline parameters and the prediction of treatment failure in patients with intravenous drug use-associated spinal epidural abscesses

OBJECTIVE

Despite the increasing incidence of spinal epidural abscess (SEA), the baseline parameters potentially predictive of treatment failure remain poorly characterized. In this study, the authors identify the relevant baseline parameters that predict multimodal treatment failure in patients with either intravenous drug use (IVDU)-associated SEA or non-IVDU-associated SEA.

METHODS

The authors reviewed the electronic medical records of a large institutional series of consecutive patients with diagnosed SEA between January 2011 and December 2017 to characterize epidemiological trends as well as the complement of baseline measures that are predictive of failure after multimodal treatment in patients with and without concomitant IVDU. The independent impact of clinical and imaging factors in detecting treatment failure was assessed by performing stepwise binary logistic regression analysis.

RESULTS

A total of 324 consecutive patients with diagnosed SEA were identified. Overall, 226 patients (69.8%) had SEA related to other causes and 98 (30.2%) had a history of recent IVDU. While non-IVDU SEA admission rates remained constant, year-over-year admissions of patients with IVDU SEA nearly tripled. At baseline, patients with IVDU SEA were distinct in many respects including younger age, greater unemployment and disability, less frequent diabetes mellitus (DM), and more frequent methicillin-resistant Staphylococcus aureus infection. However, differences in length of stay, loss to follow-up, and treatment failure did not reach statistical significance between the groups. The authors constructed independent multivariate logistic regression models for treatment failure based on identified parameters in the two cohorts. For the non-IVDU cohort, the authors identified four variables as independent factors: DM, hepatitis B/C, osteomyelitis, and compression deformity severity. In contrast, for patients with IVDU, the authors identified three variables: albumin, endocarditis, and endplate destruction. Receiver operating characteristic and area under the curve (AUC) analyses were undertaken for the multivariate models predicting the likelihood of treatment failure in the two cohorts (AUC = 0.88 and 0.89, respectively), demonstrating that the derived models could adequately predict the risk of multimodal treatment failure. Treatment failure risk factor point scales were derived for the identified variables separately for both cohorts.

CONCLUSIONS

Patients with IVDU SEA represent a unique population with a distinct set of baseline parameters that predict treatment failure. Identification of relevant prognosticating factors will allow for the design of tailored treatment and follow-up regimens.

Critical Updates on Chronic Hepatitis B Virus Infection in 2021

Chronic hepatitis B virus (HBV) infection is a global healthcare burden in the form of chronic liver disease, cirrhosis, liver failure and liver cancer. There is no definite cure for the virus and even though extensive vaccination programs have reduced the burden of liver disease in the future population, treatment options to eradicate the virus from the host are still lacking. In this review, we discuss in detail current updates on the structure and applied biology of the virus in the host, examine updates to current treatment and explore novel and state-of-the-art therapeutics in the pipeline for management of chronic HBV. Furthermore, we also specifically review clinical updates on HBV-related acute on chronic liver failure (ACLF). Current treatments for chronic HBV infection have seen important updates in the form of considerations for treating patients in the immune tolerant phase and some clarity on end points for treatment and decisions on finite therapy with nucleos(t)ide inhibitors. Ongoing cutting-edge research on HBV biology has helped us identify novel target areas in the life cycle of the virus for application of new therapeutics. Due to improvements in the area of genomics, the hope for therapeutic vaccines, vector-based treatments and focused management aimed at targeting host integration of the virus and thereby a total cure could become a reality in the near future. Newer clinical prognostic tools have improved our understanding of timing of specific treatment options for the catastrophic syndrome of ACLF secondary to reactivation of HBV. In this review, we discuss in detail pertinent updates regarding virus biology and novel therapeutic targets with special focus on the appraisal of prognostic scores and treatment options in HBV-related ACLF.

TNFA -308G>A and IL10 -1082A>G polymorphisms seem to be predictive biomarkers of chronic HCV infection

Background

Genetic changes may induce dysregulated cytokine production and affect the progression of the chronic disease caused by the hepacivirus C (HCV) because the balance of pro- and anti-inflammatory cytokines determines the outcome of infection. This study evaluated the TNFA -308G>A and IL10 -1082A>G polymorphisms in the susceptibility and progress of chronic hepatitis C.

Method

The study included 101 samples from patients with chronic hepatitis C and 300 samples from healthy donors. Polymorphisms were typed by real-time PCR and were analyzed for associations with histopathological parameters (according to METAVIR classification) and HCV viral load.

Results

The polymorphic genotype for the TNFA -308G>A variant was not present in the group of patients with chronic hepatitis C and its absence could be associated with protection against HCV infection (p = 0.0477). Patients with the polymorphic genotype of the IL10 -1082A>G polymorphism had higher HCV viral load than wild-type patients (p = 0.0428). Neither polymorphism was associated with different levels of necroinflammatory activity or fibrosis scores.

Conclusion

Our results suggest the polymorphic genotype at TNFA -308G>A as protective against chronic HCV infection, and the polymorphic genotype at the IL10 -1082A>G variant associated with higher HCV viral load. Further studies must be performed in order to confirm these associations.

Identification and Mapping of HBsAg Loss-Related B-Cell Linear Epitopes in Chronic HBV Patients by Peptide Array

Identification of immunogenic targets against hepatitis B virus (HBV)-encoded proteins will provide crucial advances in developing potential antibody therapies. In this study, 63 treatment-naïve patients with chronic HBV infection and 46 patients who achieved hepatitis B surface antigen loss (sAg loss) following antiviral treatment were recruited. Moreover, six patients who transitioned from the hepatitis B e antigen-positive chronic infection phase (eAg⁺CInf) to the hepatitis phase (eAg⁺CHep) were enrolled from real-life clinical practice. Additionally, telbivudine-treated eAg⁺CHep patients and relapsers or responders from an off-treatment cohort were longitudinally studied. The frequencies and function of B cells were assessed by flow cytometry. We devised a peptide array composed of 15-mer overlapping peptides of HBV-encoded surface (S), core (C), and polymerase (P) proteins and performed a screening on B-cell linear epitopes with sera. Naïve B cells and plasmablasts were increased, whereas total memory, activated memory (AM), and atypical memory (AtM) B cells were reduced in sAg^- patients compared with sAg⁺ patients. Importantly, longitudinal observations found that AtM B cells were associated with successful treatment withdrawal. Interestingly, we identified six S-specific dominant epitopes (S33, S34, S45, S76, S78, and S89) and one C-specific dominant epitope (C37) that reacted with the majority of sera from sAg^- patients. Of note, more B-cell linear epitopes were detected in CHep patients with alanine aminotransferase (ALT) flares than in nonflare CInf patients, and five B-cell linear epitopes (S4, S5, S10, S11, and S68) were overwhelmingly recognized by ALT flare patients. The recognition rates of epitopes on C and P proteins were significantly increased in CHep patients relative to CInf patients. Strikingly, a statistically significant elevation in the number of positive epitopes was observed when ALT nonflare patients shifted into the flare phase. Moreover, S76 identified at baseline was confirmed to be associated with a complete response after 48 weeks of telbivudine therapy. Taken together, we identified several functional cure-related B-cell linear epitopes of chronic HBV infection, and these epitopes may serve as vaccine candidates to elicit neutralizing antibodies to treat HBV infection.

Genomic characterization of rare molecular subclasses of hepatocellular carcinoma

Primary liver cancer, consisting of both cholangiocarcinoma (CCA) and hepatocellular carcinoma (HCC), is the second leading cause of cancer deaths worldwide. Our goal is to genomically characterize rare HCC subclasses to provide insight into disease biology. Leveraging The Cancer Genome Atlas (TCGA) to perform a combined analysis of CCA (n = 36) and HCC (n = 275), we integrated multiple genomic platforms, to assess transcriptional profiles, mutational signatures, and copy number patterns to uncover underlying etiology and linage specific patterns. We identified two molecular classes distinct from prototypical HCC tumors. The first, CCA-Like, although histologically indistinguishable from HCC, had enrichment of CCA mutations (IDH1, BAP1), mutational signatures, and transcriptional patterns (SOX9, KRT19). CCA-Like, however, retained a copy number landscape similar to HCC, suggesting a hepatocellular linage. The second, Blast-Like, is enriched in TP53 mutations, HBV infection, exposure related mutational signatures and transcriptionally similar to hepatoblasts. Although these subclasses are molecularly distinct, they both have a worse progression-free survival compared to classical HCC tumors, yet are clinically treated the same. The identification of and characterization of CCA-Like and Blast-Like subclasses advance our knowledge of HCC as well as represents an urgent need for the identification of class specific biomarkers and targeted therapy.

Jeffrey Damrauer, Markia Smith et al. used existing datasets from cholangiocarcinoma (CCA) and hepatocellular carcinoma (HCC) to characterize two subsets of HCC distinct from prototypical HCC tumors, based on comprehensive analysis of molecular data. The two classes differed from HCC by their copy number, gene expression and mutational signature and exhibited worse progression free survival, highlighting the need to identify class-specific biomarkers and develop targeted therapies for these forms of cancer.

Towards a Systems Immunology Approach to Understanding Correlates of Protective Immunity against HCV

Over the past decade, tremendous progress has been made in systems biology-based approaches to studying immunity to viral infections and responses to vaccines. These approaches that integrate multiple facets of the immune response, including transcriptomics, serology and immune functions, are now being applied to understand correlates of protective immunity against hepatitis C virus (HCV) infection and to inform vaccine development. This review focuses on recent progress in understanding immunity to HCV using systems biology, specifically transcriptomic and epigenetic studies. It also examines proposed strategies moving forward towards an integrated systems immunology approach for predicting and evaluating the efficacy of the next generation of HCV vaccines.

HCV Cure With Direct-Acting Antivirals Improves Liver and Immunological Markers in HIV/HCV-Coinfected Patients

Hepatitis C virus (HCV) cure after all-oral direct-acting antiviral (DAA) therapy greatly improves the liver and immune system. We aimed to assess the impact of this HCV clearance on immune system-related markers in plasma and the gene expression profile in human immunodeficiency virus (HIV)/HCV-coinfected patients with advanced cirrhosis. We performed a prospective study on 33 HIV/HCV-coinfected patients at baseline and 36 weeks after the sustained virological response. Gene expression was evaluated by RNA-seq analysis on peripheral blood mononuclear cells (PBMCs) and plasma biomarkers by multiplex immunoassays. We found a decrease in plasma biomarkers (PD1, PDL1, CXCL10, CXCL8, IL12p70, IL10, and TGFβ) and liver disease markers (stiffness measurement (LSM), hepatic venous pressure gradient (HVPG), and transaminases, among others). Furthermore, decreased plasma levels of CXCL8, CXCL10, IL10, and PD1 were associated with reduced LSM values. We also found two upregulated (HAS1 and IRG1) and 15 downregulated (CXCL11, CCL8, CCL7, CCL2, ADARB2, RRAD, MX1, SIGLEC1, IFI44L, IFI44, IFI27, IFI6, IFIT3, IFIT1B, and IFIT1) genes at the end of follow-up, all interferon-stimulated genes (ISGs) grouped into four pathways (“cytokine-cytokine receptor interaction”, “viral protein interaction with cytokine and cytokine receptor”, “chemokine signaling pathway”, and “hepatitis C”). Additionally, the decrease in most of these ISGs was significantly related to reduced LSM and HVPG values. In conclusion, HIV/HCV-coinfected patients with advanced-HCV-related cirrhosis who eradicated HCV following DAA therapy exhibited an improvement in liver disease markers and a significant decrease in plasma biomarkers and gene expression related to antiviral/inflammatory response, particularly in levels of several chemokines and ISGs.

Hepatitis E Virus Infection-Immune Responses to an Underestimated Global Threat

Infection with the hepatitis E virus (HEV) is one of the main ubiquitous causes for developing an acute hepatitis. Moreover, chronification plays a predominant role in immunocompromised patients such as transplant recipients with more frequent severe courses. Unfortunately, besides reduction of immunosuppression and off-label use of ribavirin or pegylated interferon alfa, there is currently no specific anti-viral treatment to prevent disease progression. So far, research on involved immune mechanisms induced by HEV is limited. It is very difficult to collect clinical samples especially from the early phase of infection since this is often asymptomatic. Nevertheless, it is certain that the outcome of HEV-infected patients correlates with the strength of the proceeding immune response. Several lymphoid cells have been identified in contributing either to disease progression or achieving sustained virologic response. In particular, a sufficient immune control by both CD4⁺ and CD8⁺ T cells is necessary to prevent chronic viral replication. Especially the mechanisms underlying fulminant courses are poorly understood. However, liver biopsies indicate the involvement of cytotoxic T cells in liver damage. In this review, we aimed to highlight different parts of the lymphoid immune response against HEV and point out questions that remain unanswered regarding this underestimated global threat.

A Tale of Two Viruses: Immunological Insights Into HCV/HIV Coinfection

Nearly 2.3 million individuals worldwide are coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV). Odds of HCV infection are six times higher in people living with HIV (PLWH) compared to their HIV-negative counterparts, with the highest prevalence among people who inject drugs (PWID) and men who have sex with men (MSM). HIV coinfection has a detrimental impact on the natural history of HCV, including higher rates of HCV persistence following acute infection, higher viral loads, and accelerated progression of liver fibrosis and development of end-stage liver disease compared to HCV monoinfection. Similarly, it has been reported that HCV coinfection impacts HIV disease progression in PLWH receiving anti-retroviral therapies (ART) where HCV coinfection negatively affects the homeostasis of CD4⁺ T cell counts and facilitates HIV replication and viral reservoir persistence. While ART does not cure HIV, direct acting antivirals (DAA) can now achieve HCV cure in nearly 95% of coinfected individuals. However, little is known about how HCV cure and the subsequent resolution of liver inflammation influence systemic immune activation, immune reconstitution and the latent HIV reservoir. In this review, we will summarize the current knowledge regarding the pathogenesis of HIV/HCV coinfection, the effects of HCV coinfection on HIV disease progression in the context of ART, the impact of HIV on HCV-associated liver morbidity, and the consequences of DAA-mediated HCV cure on immune reconstitution and HIV reservoir persistence in coinfected patients.

High-dimensional immune phenotyping of blood cells by mass cytometry in patients infected with hepatitis C virus

OBJECTIVES

Chronic hepatitis C virus (HCV) infection affects the immune system. Whether elimination of HCV with direct-acting antivirals (DAA) restores immunity is unclear. We used mass cytometry to get a broad and in-depth assessment of blood cell populations of patients with chronic HCV before and after DAA therapy.

METHODS

Before and 12 weeks after sustained virological response (SVR12) to DAA therapy, 22 cell populations were analysed by mass cytometry in blood collected from ten healthy control individuals and 20 HCV-infected patients with (ten patients) or without (ten patients) human immunodeficiency virus (HIV) infection.

RESULTS

HCV infection altered the frequency of 14/22 (64%) blood cell populations. At baseline, the frequencies (median, interquartile range (IQR); control, HCV, HCV/HIV) of intermediate monocytes (1.2, IQR 0.47-1.46; 1.76, IQR 0.83-2.66; 0.78, IQR 0.28-1.77), non-classical monocytes (1.11, IQR 0.49-1.26; 0.9, IQR 0.18-0.99; 0.54, IQR 0.28-1.77), conventional dendritic cells type 2 (0.55, IQR 0.35-0.59; 0.31, IQR 0.16-0.38; 0.19, IQR 0.11-0.36) and CD56^dim natural killer cells (8.08, IQR 5.34-9.79; 4.72, IQR 2.59-6.05) 3.61, IQR 2.98-5.07) were reduced by 35% to 65%, particularly in HCV/HIV co-infected patients. In contrast, activated double-negative T cells (0.07, IQR 0.06-0.10; 0.10, IQR 0.09-0.19; 0.19, IQR 0.12-0.25), activated CD4 T cells (0.28, IQR 0.21-0.36; 0.56, IQR 0.33-0.77; 0.40, IQR 0.22-0.53) and activated CD8 T cells (0.23, IQR 0.14-0.42; 0.74, IQR 0.30-1.65; 0.80, IQR 0.58-1.16) were increased 1.4 to 3.5 times. Upon stimulation with Toll-like receptor ligands, the expression of cytokines was up-regulated in 7/9 (78%) and 17/19 (89%) of the conditions in HCV- and HCV/HIV-infected patients, respectively. Most alterations persisted at SVR12.

CONCLUSIONS

Chronic HCV and HCV/HIV infections induce profound and durable perturbations of innate and adaptive immune homeostasis.

Characteristics of Peripheral Lymphocyte Subsets in Patients With Acute-On-Chronic Liver Failure Associated With Hepatitis B

Background and Aims: Acute-on-chronic liver failure (ACLF) is a rare, but dramatic clinical syndrome. There is substantial evidence suggesting that immunity-mediated inflammation plays an important role in HBV-ACLF. Our aim was to characterize the proportion and cell counts of peripheral blood lymphocyte subsets in acute-on-chronic liver failure patients caused by HBV infection.

Methods: One hundred and seventeen patients were enrolled in this study, including those with HBV-related ACLF (HBV-ACLF; n = 70), and HBV related non-ACLF patients (HBV non-ACLF; n = 47). Demographics, clinical and laboratory data at hospital admission were retrospectively analyzed. The percentage and cell count of peripheral lymphocyte subsets were evaluated by flow cytometry. Comparison analysis was performed by t-test or non-parametric Mann–Whitney U-test. Actuarial probabilities of death were calculated by the Kaplan-Meier method.

Results: Both circulating lymphocyte count and lymphocyte percentage were significantly reduced in patients with HBV-ACLF (P < 0.001). The CD8⁺ T cell, CD4⁺ T cell, and CD16⁺CD56⁺ NK cell counts were significantly decreased in HBV-ACLF. Consistently, flow cytometric analysis showed that CD8⁺ T cell counts were significantly decreased in non-survivors, while no significant differences were found in CD4⁺ T cell, CD19⁺ B cell, or CD56⁺CD16⁺ NK cell counts. Furthermore, the group with the lower CD8⁺ T cell count displayed a significantly higher mortality rate compared with the group with the higher CD8⁺ T cell count.

Conclusions: The abnormal prevalence of lymphocyte subsets may be important in the pathogenesis of HBV-ACLF. The decrease in CD8⁺ T cell counts may be related to poor survival in HBV-ACLF patients.

Effect of intestinal microbiota imbalance associated with chronic hepatitis B virus infection on the expression of microRNA‑192 and GLP‑1

It has been reported that hepatitis B virus (HBV) infection has an impact on intestinal microbiota imbalance to induce diabetes mellitus (DM), but the underlying mechanisms still remain to be explored. The present study aimed to investigate the regulatory role of microRNA‑192 (miR‑192‑5p) and glucagon‑like peptide‑1 (GLP‑1) in intestinal microbiota imbalance by recruiting patients with DM infected with HBV. In the present study, patients with HBV infection and different levels of alanine transaminase (ALT) were recruited and divided into three groups. Intestinal microbiota analysis was performed to evaluate the fecal bacterial composition of patients in various groups. Quantitative PCR was performed to explore the differential expression of miR‑192‑5p and GLP‑1 in the feces, peripheral blood and intestinal mucosal tissue samples of each patient. Immunohistochemistry was used to assess the expression of GLP‑1 protein in the intestinal mucosal tissue samples. Luciferase assays were performed by cell transfection of miR‑192‑5p mimics/precursors/inhibitors to study the inhibitory effect of miR‑192‑5p on GLP‑1 expression. Intestinal microbiota imbalance was observed in hepatitis B surface antigen (HBsAg)‑positive patients with high ALT. The expression of miR‑192‑5p was significantly elevated in the feces, peripheral blood and intestinal mucosal tissue samples of HBsAg‑positive patients with high ALT along with decreased GLP‑1 mRNA and protein expression. Luciferase activity of GLP‑1 vector was inhibited by miR‑192‑5p mimics and promoted by miR‑192‑5p inhibitors. Transfection of miR‑192‑5p precursors resulted in upregulation of miR‑192‑5p and downregulation of GLP‑1, while miR‑192‑5p inhibitors remarkably suppressed the expression of miR‑192‑5p and notably induced the expression of GLP‑1. These results showed a regulatory network involving HBV infection, intestinal microbiota imbalance, and miR‑192‑5p and GLP‑1 expression.

A Continuous Model of Three Scenarios of the Infection Process with Delayed Immune Response Factors

The course of an infection was modeled as a controlled nonlinear process. Understanding the substantial differences observed in the trajectory of the disease caused by the new coronavirus SARS-CoV-2 is of critical importance at the moment. Numerous factors have been considered to explain the fact that symptoms vary highly among different people and the infection transmission rate varies among local populations. Virus replication within the host cell and the development of an immune response to virus antigens in the body are two interdependent processes, which have aftereffects and depend on the preexisting states of the cell and virus populations. Different scenarios with the same input parameters are necessary to consider for modeling the properties of the states. The efficiency of the immune response is the most important factor, including the time it takes to develop defense responses from three levels of the immune system, which is a complex system of the body. A computational description of infection scenarios was proposed on the basis of a delay differential equation with two values of the time lag. In the new model, transitions between phases of infectious disease depend on the initial virus dose and the delayed immune response to infection. A variation in the dose of the virus and response time can lead to a transition from an acute phase of the disease with overt symptoms to a chronic phase or fatal outcome. Asymptomatic transmission of viral infection was calculated and described in the model as a situation where the virus is rapidly and efficiently suppressed after a short replication phase, while still persisting in the body in minor amounts. An analysis of the model behavior is consistent with the theory that the initial number of virions can affect the quality of the immune response. The reasons that high individual differences are observed in the trajectory of COVID-19 disease and the formation of types of the immune response to coronavirus are still poorly understood. Known trajectories of hepatitis C virus (HCV) infection were used as a basis for model scenarios.

Acute Infection of Viral Pathogens and Their Innate Immune Escape

Viral infections can cause rampant disease in human beings, ranging from mild to acute, that can often be fatal unless resolved. An acute viral infection is characterized by sudden or rapid onset of disease, which can be resolved quickly by robust innate immune responses exerted by the host or, instead, may kill the host. Immediately after viral infection, elements of innate immunity, such as physical barriers, various phagocytic cells, group of cytokines, interferons (IFNs), and IFN-stimulated genes, provide the first line of defense for viral clearance. Innate immunity not only plays a critical role in rapid viral clearance but can also lead to disease progression through immune-mediated host tissue injury. Although elements of antiviral innate immunity are armed to counter the viral invasion, viruses have evolved various strategies to escape host immune surveillance to establish successful infections. Understanding complex mechanisms underlying the interaction between viruses and host’s innate immune system would help develop rational treatment strategies for acute viral infectious diseases. In this review, we discuss the pathogenesis of acute infections caused by viral pathogens and highlight broad immune escape strategies exhibited by viruses.

Molecular Mechanisms during Hepatitis B Infection and the Effects of the Virus Variability

The immunopathogenesis and molecular mechanisms involved during a hepatitis B virus (HBV) infection have made the approaches for research complex, especially concerning the patients’ responses in the course of the early acute stage. The study of molecular bases involved in the viral clearance or persistence of the infection is complicated due to the difficulty to detect patients at the most adequate points of the disease, especially in the time lapse between the onset of the infection and the viral emergence. Despite this, there is valuable data obtained from animal and in vitro models, which have helped to clarify some aspects of the early immune response against HBV infection. The diversity of the HBV (genotypes and variants) has been proven to be associated not only with the development and outcome of the disease but also with the response to treatments. That is why factors involved in the virus evolution need to be considered while studying hepatitis B infection. This review brings together some of the published data to try to explain the immunological and molecular mechanisms involved in the different stages of the infection, clinical outcomes, viral persistence, and the impact of the variants of HBV in these processes.

Treg cells in the course of chronic hepatitis C virus infection partially normalize in longitudinal observation after successful DAA treatment regardless of hepatic fibrosis stage

AIM OF THE STUDY

Elevated circulating CD4+ CD25+ Foxp3+ regulatory T cells in patients with chronic hepatitis C (CHC) play an unspecified role in liver fibrosis development. This study aimed to determine whether Treg cells diminish after successful treatment with directacting antivirals (DAA) in patients at different liver fibrosis stages.

MATERIAL AND METHODS

We examined 44 patients with CHC (including 29 with liver cirrhosis) seven days before DAA treatment (T0), six months later (T1) and then 22 of them were examined one year (T2) after the first dose. Subsequently, these were compared with 28 volunteers without hepatitis C virus (HCV) (15 with excessive alcohol intake). We assessed the degree of liver fibrosis with FibroScan, aspartate transaminase (AST) to platelet ratio index (APRI), FibroIndex, the Forns index and Fib-4. Circulating Treg cells were measured using flow cytometry.

RESULTS

All patients achieved a sustained virological response (SVR). After the treatment, all liver fibrosis indicators decreased significantly. The number of circulating Tregs was lower in healthy controls than in patients with CHC (0.0066 × 103 cells/µl and 0.0084 × 103 cells/µl, respectively, p = 0.048). After the treatment we observed an insignificant change to 0.0047 × 103 cells/µl for T1 (p > 0.05) and a significant fall to 0.0041 × 103 cells/µl for T2 (p = 0.03). There was no correlation between the degree of hepatic fibrosis and number of Tregs or post-treatment dynamics.

CONCLUSIONS

Our study shows that Treg cells normalize gradually over a prolonged period of time after a successful DAA treatment. Their number and dynamics remain independent of liver fibrosis degree. The correlation of this revelation with metabolic disorders, increased susceptibility to infections or persistent risk of HCC remains unclear.

Ultrasmall Copper (I) Sulfide Nanoparticles Prevent Hepatitis B Virus Infection

Hepatitis B virus (HBV) poses a severe threat to public health and social development. Here, we synthesized 4±0.5 nm copper (I) sulfide (Cu₂ S) nanoparticles (NPs) with 46 mdeg chiroptical property at 530 nm to selectively cleavage HBV core antigen (HBcAg) and effectively blocked HBV assembly and prevented HBV infection both in vitro and in vivo under light at 808 nm. Experimental analysis showed that the chiral Cu₂ S NPs specific bound with the functional domain from phenylalanine₂₃ (F₂₃ ) to leucine₃₀ (L₃₀ ) from HBcAg primary sequence and the cutting site was between amino acid residues F₂₄ and proline₂₅ (P₂₅ ). Under excitation at 808 nm, the intracellular HBcAg concentration was reduced by 95 %, and in HBV transgenic mice, the levels of HBV surface antigen (HBsAg) and HBV DNA were decreased by 93 % and 86 %, respectively. Together, these results reveal the potential nanomedicine for HBV control and provide fresh tools for viral infection.