Hepatitis B virus infection and immunopathogenesis in a humanized mouse model: induction of human-specific liver fibrosis and M2-like macrophages

JAK3-deficient mini-pigs exhibit impaired lymphoid organogenesis, intestinal structure, and leukocyte/cytokine production

INTRODUCTION

Severe combined immunodeficiency (SCID) mini-pigs are a highly versatile model for human disease research and regenerative medicine.

OBJECTIVES

This study aims to generate a novel JAK3-deficient mini-pig model with a human-like immune system and to elucidate how JAK3 plays an important role in immune system.

METHODS

JAK3 and RAG2 knockout (KO) mini-pigs were generated using CRISPR/Cas9 and somatic cell nuclear transfer. These mini-pigs were transferred to a sterilized isolator within a specific pathogen-free facility. Phenotypic characteristics and clinical manifestations were analyzed through histological and hematological analysis of SCID mini-pigs to explore the unique role of JAK3 in immune functions.

RESULTS

JAK3 KO was characterized by defects in T and NK cells, very low levels of B cells, and a complete absence of thymus and lymph nodes. Notably, JAK3 KO mini-pigs had significantly reduced numbers of monocytes in peripheral blood, macrophages in tissue, and inflammatory cytokines, suggesting that JAK3 KO can induce a broad immunodeficiency that extends to the myeloid system as well as the lymphoid. Moreover, JAK3 KO mini-pigs had intestinal abnormalities similar to those of patients.

CONCLUSION

These results suggest that JAK3 KO mini-pigs can be used as an effective model for the development of therapies for SCID patients, as well as for regenerative medicine applications such as the development of patient-specific artificial organs.

Engineering Mice to Study Human Immunity

Humanized mice, which carry a human hematopoietic and immune system, have greatly advanced our understanding of human immune responses and immunological diseases. These mice are created via the transplantation of human hematopoietic stem and progenitor cells into immunocompromised murine hosts further engineered to support human hematopoiesis and immune cell growth. This article explores genetic modifications in mice that enhance xeno-tolerance, promote human hematopoiesis and immunity, and enable xenotransplantation of human tissues with resident immune cells. We also discuss genetic editing of the human immune system, provide examples of how humanized mice with humanized organs model diseases for mechanistic studies, and highlight the roles of these models in advancing knowledge of organ biology, immune responses to pathogens, and preclinical drugs tested for cancer treatment. The integration of multi-omics and state-of-the art approaches with humanized mouse models is crucial for bridging existing human data with causality and promises to significantly advance mechanistic studies.

Potential role of liver-resident CD3+ macrophages in HBV clearance in a mouse hepatitis B model

Background & Aims

Chronic HBV infection usually causes cirrhosis and hepatocellular carcinoma. Comparative investigations of acute and chronic HBV cases would help determine the immune responses crucial for viral clearance.

Methods

A fast-cleared HBV mouse model was established in Alb-Cre mice via hydrodynamic injection of HBV plasmid, while persistent HBV model mice were generated via recombinant covalently closed circular DNA-adeno-associated virus 8 infection. The single-cell transcriptomes of CD45+ intrahepatic non-parenchymal cells from these mice were conducted. Multiplexed immunohistochemistry and flow cytometry were used to confirm the findings from single-cell transcriptomes. Transwell, coculture, and adoptive transfer experiments were performed to study the generation and functions of macrophages.

Results

Twenty-four clusters of immune cells were identified. Myeloid cells, including granulocytes, monocytes, and dendritic cells, are activated early in HBV fast-cleared mice. Significantly, a cluster of CD3+ macrophages was found in the viral clearance phase, which was confirmed in liver tissue from five acute patients with HBV. These cells highly expressed CXCL1, tumor necrosis factor alpha, and HBsAg-specific T cell receptors. The transwell assay revealed that CD3+ macrophages originate from macrophages (n = 6). T cells and anti-HBsAg antibodies are indispensable for their differentiation, which was further confirmed in T- and/or B-cell-deficient mice. Interestingly, these CD3+ macrophages capable of killing peptide-loaded hepatocytes and engulfing IgG-coated beads were persistently detectable in the mouse liver for 10 weeks after HBV clearance. The expression levels of CD5L and Bcl2, two classical antiapoptotic proteins, increased (p <0.001), suggesting that the CD3+ macrophages are long-term resident populations. Finally, adoptive transfer of CD3+ macrophages accelerated HBV clearance in mice (n = 5, p <0.01).

Conclusions

We identified long-term polyfunctional CD3+ macrophages residing in HBV fast-cleared livers that could help elucidate the immune responses involved in eliminating HBV.

Impact and implications

The liver is a special organ with unique immune characteristics and tolerance to foodborne antigens. Chronic infections can develop in newborns after exposure to HBV; however, acute infections usually occur in adults, indicating that immune cells in the liver tissue microenvironment can also effectively fight against the virus. Nevertheless, the mechanisms involved in acute HBV infection have rarely been studied. In this study, we identified a macrophage population with both T cell and macrophage characteristics in the livers of acute HBV model mice and revealed that these macrophages play important roles in HBV clearance. Moreover, we confirmed that this population is derived from macrophages in the presence of virus-specific T cells and antibodies. This finding highlights the complexity of antiviral immune responses in liver microenvironments.

Can Humanized Immune System Mouse and Rat Models Accelerate the Development of Cytomegalovirus-Based Vaccines Against Infectious Diseases and Cancers?

Over the past three decades, immunodeficient mouse models carrying human immune cells, with or without human lymphoid tissues, termed humanized immune system (HIS) rodent models, have been developed to recapitulate the human immune system and associated immune responses. HIS mouse models have successfully modeled many human-restricted viral infections, including those caused by human cytomegalovirus (HCMV) and human immunodeficiency virus (HIV). HIS mouse models have also been used to model human cancer immunobiology, which exhibits differences from murine cancers in traditional mouse models. Variants of HIS mouse models that carry human liver cells, lung tissue, skin tissue, or human patient-derived tumor xenografts and human hematopoietic stem cells-derived-human immune cells with or without lymphoid tissue xenografts have been developed to probe human immune responses to infections and human tumors. HCMV-based vaccines are human-restricted, which poses limitations for mechanistic and efficacy studies using traditional animal models. The HCMV-based vaccine approach is a promising vaccine strategy as it induces robust effector memory T cell responses that may be critical in preventing and rapidly controlling persistent viral infections and cancers. Here, we review novel HIS mouse models with robust human immune cell development and primary and secondary lymphoid tissues that could address many of the limitations of HIS mice in their use as animal models for HCMV-based vaccine research. We also reviewed novel HIS rat models, which could allow long-term (greater than one year) vaccinology studies and better recapitulate human pathophysiology. Translating laboratory research findings to clinical application is a significant bottleneck in vaccine development; HIS rodents and related variants that more accurately model human immunology and diseases could increase the translatability of research findings.

CD163 impairs HBV clearance in mice by regulating intrahepatic T cell immune response via an IL-10-dependent mechanism

BACKGROUND & AIMS

Chronic hepatitis B (CHB) arises from a persistent hepatitis B virus (HBV) infection, complicating efforts for a functional cure. Kupffer cells (KCs), liver-resident macrophages, are pivotal in mediating immune tolerance to HBV. Although CD163 marks M2-polarized KCs, its precise role in HBV infection remains unclear and warrants further investigation.

METHODS

CD163 expression in liver tissues of patients with CHB was analyzed using the Gene Expression Omnibus (GEO) database. Cd163 knockout mice were utilized to establish HBV-persistent mouse model, and CD163 deficiency effect on HBV viral markers and T cell immune responses were examined in vivo and in vitro.

RESULTS

CD163 expression was elevated and correlated with ALT levels in the liver of patients with CHB. In HBV-persistent mouse model, CD163 deficiency facilitated the clearance of HBsAg, HBeAg, HBV DNA, and HBcAg. Additionally, CD163 deficiency promoted the differentiation of naïve T cells into HBV-specific effector T cells. Further, we found that CD163 deficiency reduces KCs-derived IL-10 secretion, and blocking IL-10 further strengthens the enhanced HBV-specific T cell response due to CD163 deficiency.

CONCLUSIONS

Our findings indicate that CD163 deficiency enhances the HBV-specific T cell response, thereby facilitating HBV clearance through reducing KCs-derived IL-10 secretion. This suggests that CD163 may serve as a potential target for the restoration of exhausted T cell function.

Developing T Cell Epitope-Based Vaccines Against Infection: Challenging but Worthwhile

T cell epitope-based vaccines are designed to elicit long-lived pathogen-specific memory T cells that can quickly activate protective effector functions in response to subsequent infections. These vaccines have the potential to provide sustained protection against mutated variants, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which are increasingly capable of evading neutralizing antibodies. Recent advancements in epitope discovery, T cell receptor analysis, and bioinformatics have enabled the precise selection of epitopes and the sophisticated design of epitope-based vaccines. This review outlines the development process for T cell epitope-based vaccines. We summarize the current progress in T cell epitope discovery technologies, highlighting the advantages and disadvantages of each method. We also examine advancements in the design and optimization of epitope-based vaccines, particularly through bioinformatics tools. Additionally, we discuss the challenges of validating the accurate processing and presentation of individual epitopes and establishing suitable rodent models to evaluate vaccine immunogenicity and protective efficacy.

Current Treatment Regimens and Promising Molecular Therapies for Chronic Hepatobiliary Diseases

Chronic hepatobiliary damage progressively leads to fibrosis, which may evolve into cirrhosis and/or hepatocellular carcinoma. The fight against the increasing incidence of liver-related morbidity and mortality is challenged by a lack of clinically validated early-stage biomarkers and the limited availability of effective anti-fibrotic therapies. Current research is focused on uncovering the pathogenetic mechanisms that drive liver fibrosis. Drugs targeting molecular pathways involved in chronic hepatobiliary diseases, such as inflammation, hepatic stellate cell activation and proliferation, and extracellular matrix production, are being developed. Etiology-specific treatments, such as those for hepatitis B and C viruses, are already in clinical use, and efforts to develop new, targeted therapies for other chronic hepatobiliary diseases are ongoing. In this review, we highlight the major molecular changes occurring in patients affected by metabolic dysfunction-associated steatotic liver disease, viral hepatitis (Delta virus), and autoimmune chronic liver diseases (autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis). Further, we describe how this knowledge is linked to current molecular therapies as well as ongoing preclinical and clinical research on novel targeting strategies, including nucleic acid-, mesenchymal stromal/stem cell-, and extracellular vesicle-based options. Much clinical development is obviously still missing, but the plethora of promising potential treatment strategies in chronic hepatobiliary diseases holds promise for a future reversal of the current increase in morbidity and mortality in this group of patients.

Mice Engrafted with Human Liver Cells

Rodents are commonly employed to model human liver conditions, although species differences can restrict their translational relevance. To overcome some of these limitations, researchers have long pursued human hepatocyte transplantation into rodents. More than 20 years ago, the first primary human hepatocyte transplantations into immunodeficient mice with liver injury were able to support hepatitis B and C virus infections, as these viruses cannot replicate in murine hepatocytes. Since then, hepatocyte chimeric mouse models have transitioned into mainstream preclinical research and are now employed in a diverse array of liver conditions beyond viral hepatitis, including malaria, drug metabolism, liver-targeting gene therapy, metabolic dysfunction-associated steatotic liver disease, lipoprotein and bile acid biology, and others. Concurrently, endeavors to cotransplant other cell types and humanize immune and other nonparenchymal compartments have seen growing success. Looking ahead, several challenges remain. These include enhancing immune functionality in mice doubly humanized with hepatocytes and immune systems, efficiently creating mice with genetically altered grafts and reliably humanizing chimeric mice with renewable cell sources such as patient-specific induced pluripotent stem cells. In conclusion, hepatocyte chimeric mice have evolved into vital preclinical models that address many limitations of traditional rodent models. Continued improvements may further expand their applications.

YAP mediates HIV-related liver fibrosis

Background & Aims

HIV accelerates liver fibrosis attributable to multiple etiologies, including HCV, HBV, and steatotic liver disease. Evidence also suggests that HIV infection itself is associated with liver fibrogenesis. Recent studies have implicated Yes-associated protein 1 (YAP1) and the upstream lysophosphatidic acid (LPA)/PI3K/AKT pathway as critical regulators of hepatic fibrogenesis, and suggest a connection to HIV-related liver fibrosis. However, the relationship between YAP/PI3K/AKT pathway activation and HIV-related liver fibrosis remains uncertain.

Methods

qPCR, western blot, immunofluorescence, and ELISA (replicates n ≥3) were performed in an unbiased humanized mouse model (NRG-hu HSC mice, n = 6), the precision cut liver slice ex vivo model, and both traditional in vitro models as well as a 3D spheroid system.

Results

YAP target gene mRNA and protein levels (ANKRD, CTGF, CYR61) were upregulated across all models exposed to HIV. Humanized mice infected with HIV had significant increases in the percentage of YAP-positive nuclei (2.2-fold) and the percentage area of Sirius Red collagen staining (3.3-fold) compared to control mice. Serum concentrations of LPA were increased 5.8-fold in people living with HIV compared to healthy controls. Modulation of LPAR1, PI3K, and AKT by either inhibitors or small-interfering RNAs abrogated the fibrotic effects of HIV exposure and downregulated YAP target genes within cultured liver cells.

Conclusions

The LPAR/PI3K/AKT axis is vital for the activation of YAP and hepatic fibrogenesis due to HIV infection. This novel mechanistic insight suggests new pharmacologic targets for treatment of liver fibrosis in people living with HIV.

Impact and implications

There are currently no FDA-approved treatments for cirrhosis, while liver disease is the second leading cause of mortality among people living with HIV after AIDS. Increased lysophosphatidic acid concentrations and AKT activation after HIV infection found in recent work suggest that the Hippo pathway may be a key regulator of HIV-related fibrogenesis. By linking lysophosphatidic acid signaling, YAP activation, and HIV-related fibrogenesis, this mechanism presents a target for future research into therapeutic interventions for not only HIV but also other liver diseases, e.g. metabolic dysfunction- or alcohol-associated liver disease.

Monocyte and Macrophage Functions in Oncogenic Viral Infections

Monocytes and macrophages are part of innate immunity and constitute the first line of defense against pathogens. Bone marrow-derived monocytes circulate in the bloodstream for one to three days and then typically migrate into tissues, where they differentiate into macrophages. Circulatory monocytes represent 5% of the nucleated cells in normal adult blood. Following differentiation, macrophages are distributed into various tissues and organs to take residence and maintain body homeostasis. Emerging evidence has highlighted the critical role of monocytes/macrophages in oncogenic viral infections, mainly their crucial functions in viral persistence and disease progression. These findings open opportunities to target innate immunity in the context of oncogenic viruses and to explore their potential as immunotherapies.

Macrophage fate: to kill or not to kill?

Macrophages are dynamic innate immune cells that either reside in tissue, serving as sentinels, or recruited as monocytes from bone marrow into inflamed and infected tissue. In response to cues in the tissue microenvironment (TME), macrophages polarize on a continuum toward M1 or M2 with diverse roles in progression and resolution of disease. M1-like macrophages exhibit proinflammatory functions with antimicrobial and anti-tumorigenic activities, while M2-like macrophages have anti-inflammatory functions that generally resolve inflammatory responses and orchestrate a tissue healing process. Given these opposite phenotypes, proper spatiotemporal coordination of macrophage polarization in response to cues within the TME is critical to effectively resolve infectious disease and regulate wound healing. However, if this spatiotemporal coordination becomes disrupted due to persistent infection or dysregulated coagulation, macrophages' inappropriate response to these cues will result in the development of diseases with clinically unfavorable outcomes. Since plasticity and heterogeneity are hallmarks of macrophages, they are attractive targets for therapies to reprogram toward specific phenotypes that could resolve disease and favor clinical prognosis. In this review, we discuss how basic science studies have elucidated macrophage polarization mechanisms in TMEs during infections and inflammation, particularly coagulation. Therefore, understanding the dynamics of macrophage polarization within TMEs in diseases is important in further development of targeted therapies.

Engineered Regenerative and Adhesive Hydrogel for Concurrent Sealing and Healing of Enterocutaneous Fistulas

In addressing the intricate challenges of enterocutaneous fistula (ECF) treatment, such as internal bleeding, effluent leakage, inflammation, and infection, our research is dedicated to introducing a regenerative adhesive hydrogel that can seal and expedite the healing process. A double syringe setup was utilized, with dopagelatin and platelet-rich plasma (PRP) in one syringe and Laponite and sodium periodate in another. The hydrogel begins to cross-link immediately after passing through a mixing tip and exhibits tissue adhesive properties. Results demonstrated that PRP deposits within the pores of the cross-linked hydrogel and releases sustainably, enhancing its regenerative capabilities. The addition of PRP further improved the mechanical properties and slowed down the degradation of the hydrogel. Furthermore, the hydrogel demonstrated cytocompatibility, hemostatic properties, and time-dependent macrophage M1 to M2 phase transition, suggesting the anti-inflammatory response of the material. In an in vitro bench test simulating high-pressure fistula conditions, the hydrogel effectively occluded pressures up to 300 mmHg. In conclusion, this innovative hydrogel holds promise for ECF treatment and diverse fistula cases, marking a significant advancement in its therapeutic approaches.

Understanding lactate in the development of Hepatitis B virus-related hepatocellular carcinoma

Hepatitis B Virus (HBV) is a hepatotropic virus that can establish a persistent and chronic infection in humans. Chronic hepatitis B (CHB) infection is associated with an increased risk of hepatic decompensation, cirrhosis, and hepatocellular carcinoma (HCC). Lactate level, as the end product of glycolysis, plays a substantial role in metabolism beyond energy production. Emerging studies indicate that lactate is linked to patient mortality rates, and HBV increases overall glucose consumption and lactate production in hepatocytes. Excessive lactate plays a role in regulating the tumor microenvironment (TME), immune cell function, autophagy, and epigenetic reprogramming. The purpose of this review is to gather and summarize the existing knowledge of the lactate's functions in the dysregulation of the immune system, which can play a crucial role in the development of HBV-related HCC. Therefore, it is reasonable to hypothesize that lactate with intriguing functions can be considered an immunomodulatory metabolite in immunotherapy.

Therapeutic potential of Angelica sinensis in addressing organ fibrosis: A comprehensive review

Fibrosis-related diseases (FRD) include conditions like myocardial fibrosis, pulmonary fibrosis, hepatic fibrosis, renal fibrosis, and others. The impact of fibrosis can be severe, causing organ dysfunction, reduced functionality, and even organ failure, leading to significant health issues. Currently, there is a lack of effective modern anti-fibrosis drugs in clinical practice. However, Chinese medicine has a certain beneficial effect on the treatment of such diseases. Angelica sinensis, with its considerable medicinal value, has garnered attention for its anti-fibrosis properties in recent investigations. In the past few years, there has been a growing number of experimental inquiries into the impact of angelica polysaccharide (ASP), angelica water extract, angelica injection, and angelica compound preparation on fibrosis-associated ailments, piquing the interest of researchers. This paper aims to consolidate recent advances in the study of Angelica sinensis for the treatment of fibrosis-related disorders, offering insights for prospective investigations. Literature retrieval included core electronic databases, including Baidu Literature, CNKI, Google-Scholar, PubMed, and Web of Science. The applied search utilized specified keywords to extract relevant information on the pharmacological and phytochemical attributes of plants. The investigation revealed that Angelica sinensis has the potential to impede the advancement of fibrotic diseases by modulating inflammation, oxidative stress, immune responses, and metabolism. ASP, Angelica sinensis extract, Angelica sinensis injection, and Angelica sinensis compound preparation were extensively examined and discussed. These constituents demonstrated significant anti-fibrosis activity. In essence, this review seeks to gain a profound understanding of the role of Angelica sinensis in treating fiber-related diseases. Organ fibrosis manifests in nearly all tissues and organs, posing a critical challenge to global public health due to its widespread occurrence, challenging early diagnosis, and unfavorable prognosis. Despite its prevalence, therapeutic options are limited, and their efficacy is constrained. Over the past few years, numerous studies have explored the protective effects of traditional Chinese medicine on organ fibrosis, with Angelica sinensis standing out as a multifunctional natural remedy. This paper provides a review of organ fibrosis pathogenesis and summarizes the recent two decades' progress in treating fibrosis in various organs such as the liver, lung, kidney, and heart. The review highlights the modulation of relevant signaling pathways through multiple targets and channels by the effective components of Angelica sinensis, whether used as a single medicine or in compound prescriptions.

Efficacy of immunotherapy in hepatocellular carcinoma: Does liver disease etiology have a role?

The systemic treatment of hepatocellular carcinoma (HCC) is changing rapidly. After a decade of tyrosine kinase inhibitors (TKIs), as the only therapeutic option for the treatment of advanced HCC, in the last few years several phase III trials demonstrated the efficacy of immune checkpoint inhibitors (ICIs). The combination of the anti-PD-L1 atezolizumab and the anti-vascular endothelial growth factor (VEGF) bevacizumab demonstrated the superiority over sorafenib and currently represents the standard of care treatment for advanced HCC. In addition, the combination of durvalumab (an anti-PD-L1) and tremelimumab (an anti-CTLA4) proved to be superior to sorafenib, and in the same trial durvalumab monotherapy showed non-inferiority compared to sorafenib. However, early reports suggest an influence of HCC etiology in modulating the response to these drugs. In particular, a lower effectiveness of ICIs has been suggested in patients with non-viral HCC (in particular non-alcoholic fatty liver disease). Nevertheless, randomized controlled trials available to date have not been stratified for etiology and data suggesting a possible impact of etiology in the outcome of patients managed with ICIs derive from subgroup not pre-specified analyses. In this review, we aim to examine the potential impact of HCC etiology on the response to immunotherapy regimens for HCC.

Effect of ozone gas on viral kinetics and liver histopathology in hepatitis C patients

OBJECTIVES

We examine how well ozone/oxygen gas therapy treats chronic hepatitis C patients with varying degrees of liver fibrosis. Also to study the effect of giving multiple anti-oxidants with the ozone/oxygen gas mixture, to see if this addition would have any additive or synergistic effect.

METHODS

Two hundred and twenty three patients with chronic hepatitis C. Liver biopsies were carried out at after 12 weeks of administering an ozone/oxygen gas mixture.

RESULTS

The mean stage of fibrosis decreased from 1.98 to 1.41 and the mean grade of inflammation decreased from 10.08 to 7.94, both with a p value less than 0.001. After 12 weeks of treatment, mean PCR values increased. No single significant complication was recorded in a total of >9,000 settings of ozone therapy.

CONCLUSIONS

Ozone oxygen gas mixture is safe and effective in treatment of hepatic fibrosis due to chronic viral hepatitis C.

Hepatitis B virus e antigen induces atypical metabolism and differentially regulates programmed cell deaths of macrophages

Macrophages can undergo M1-like proinflammatory polarization with low oxidative phosphorylation (OXPHOS) and high glycolytic activities or M2-like anti-inflammatory polarization with the opposite metabolic activities. Here we show that M1-like macrophages induced by hepatitis B virus (HBV) display high OXPHOS and low glycolytic activities. This atypical metabolism induced by HBV attenuates the antiviral response of M1-like macrophages and is mediated by HBV e antigen (HBeAg), which induces death receptor 5 (DR5) via toll-like receptor 4 (TLR4) to induce death-associated protein 3 (DAP3). DAP3 then induces the expression of mitochondrial genes to promote OXPHOS. HBeAg also enhances the expression of glutaminases and increases the level of glutamate, which is converted to α-ketoglutarate, an important metabolic intermediate of the tricarboxylic acid cycle, to promote OXPHOS. The induction of DR5 by HBeAg leads to apoptosis of M1-like and M2-like macrophages, although HBeAg also induces pyroptosis of the former. These findings reveal novel activities of HBeAg, which can reprogram mitochondrial metabolism and trigger different programmed cell death responses of macrophages depending on their phenotypes to promote HBV persistence.

Development of animal models for emerging infectious diseases by breaking the barrier of species susceptibility to human pathogens

Outbreaks of emerging infectious diseases pose a serious threat to public health security, human health and economic development. After an outbreak, an animal model for an emerging infectious disease is urgently needed for studying the etiology, host immune mechanisms and pathology of the disease, evaluating the efficiency of vaccines or drugs against infection, and minimizing the time available for animal model development, which is usually hindered by the nonsusceptibility of common laboratory animals to human pathogens. Thus, we summarize the technologies and methods that induce animal susceptibility to human pathogens, which include viral receptor humanization, pathogen-targeted tissue humanization, immunodeficiency induction and screening for naturally susceptible animal species. Furthermore, the advantages and deficiencies of animal models developed using each method were analyzed, and these will guide the selection of susceptible animals and potentially reduce the time needed to develop animal models during epidemics.

Qijia rougan formula ameliorates ECM deposition in hepatic fibrosis by regulating the JAK1/STAT6-microRNA-23a feedback loop in macrophage M2 polarization

Hepatic fibrosis is the critical pathological stage in the progression of chronic liver disease to cirrhosis and hepatocellular carcinoma (HCC). However, no approved anti-hepatic fibrosis drugs are available currently. Qijia Rougan Formula (QRF) is a traditional Chinese medicine (TCM) with significant clinical efficacy on hepatic fibrosis. It was derived from Sanjiasan, a famous decoction documented in the Book of Treatise on the Pestilence in the Ming Dynasty of China. However, the underlying regulatory mechanisms remain elusive. This study further confirmed the therapeutic effects of QRF on hepatic fibrosis and dissected its underlying molecular mechanisms from the perspective of macrophage M2 polarization, one of the critical events in hepatic fibrosis. Experimentally, QRF significantly improved extracellular matrix (ECM) deposition and fibrosis in the liver of model rats. QRF diminished the proportion of M2 macrophages, decreased the levels of TGF-β, PDGFB and IL-10, and regulated the expression of p-JAK1, p-STAT6, JAK1 and microRNA-23a both in vitro and in vivo. Collectively, it was confirmed that QRF effectively improves liver function and hepatocyte damage, and reduces ECM deposition. QRF ameliorates hepatic fibrosis by regulating JAK1/STAT6-microRNA-23a negative feedback loop to inhibit macrophage M2 polarization and thus reduce ECM deposition. Our study illustrates the potential of QRF for hepatic fibrosis therapy, suggesting that QRF is a promising anti-hepatic fibrosis drug candidate.

Regulation of Mitochondrial Metabolism by Hepatitis B Virus

Mitochondria play important roles in the synthesis of ATP, the production of reactive oxygen species, and the regulation of innate immune response and apoptosis. Many viruses perturb mitochondrial activities to promote their replication and cause cell damage. Hepatitis B virus (HBV) is a hepatotropic virus that can cause severe liver diseases, including cirrhosis and hepatocellular carcinoma (HCC). This virus can also alter mitochondrial functions and metabolism to promote its replication and persistence. In this report, we summarize recent research progress on the interaction between HBV and mitochondrial metabolism, as well as the effect this interaction has on HBV replication and persistence.

Single-cell RNA sequencing of liver fine-needle aspirates captures immune diversity in the blood and liver in chronic hepatitis B patients

BACKGROUND AND AIMS

HBV infection is restricted to the liver, where it drives exhaustion of virus-specific T and B cells and pathogenesis through dysregulation of intrahepatic immunity. Our understanding of liver-specific events related to viral control and liver damage has relied almost solely on animal models, and we lack useable peripheral biomarkers to quantify intrahepatic immune activation beyond cytokine measurement. Our objective was to overcome the practical obstacles of liver sampling using fine-needle aspiration and develop an optimized workflow to comprehensively compare the blood and liver compartments within patients with chronic hepatitis B using single-cell RNA sequencing.

APPROACH AND RESULTS

We developed a workflow that enabled multi-site international studies and centralized single-cell RNA sequencing. Blood and liver fine-needle aspirations were collected, and cellular and molecular captures were compared between the Seq-Well S 3 picowell-based and the 10× Chromium reverse-emulsion droplet-based single-cell RNA sequencing technologies. Both technologies captured the cellular diversity of the liver, but Seq-Well S 3 effectively captured neutrophils, which were absent in the 10× dataset. CD8 T cells and neutrophils displayed distinct transcriptional profiles between blood and liver. In addition, liver fine-needle aspirations captured a heterogeneous liver macrophage population. Comparison between untreated patients with chronic hepatitis B and patients treated with nucleoside analogs showed that myeloid cells were highly sensitive to environmental changes while lymphocytes displayed minimal differences.

CONCLUSIONS

The ability to electively sample and intensively profile the immune landscape of the liver, and generate high-resolution data, will enable multi-site clinical studies to identify biomarkers for intrahepatic immune activity in HBV and beyond.

Crimean-Congo Hemorrhagic Fever Virus: Progress in Vaccine Development

Crimean-Congo hemorrhagic fever virus (CCHFV), a member of the Nairoviridae family and Bunyavirales order, is transmitted to humans via tick bites or contact with the blood of infected animals. It can cause severe symptoms, including hemorrhagic fever, with a mortality rate between 5 to 30%. CCHFV is classified as a high-priority pathogen by the World Health Organization (WHO) due to its high fatality rate and the absence of effective medical countermeasures. CCHFV is endemic in several regions across the world, including Africa, Europe, the Middle East, and Asia, and has the potential for global spread. The emergence of the disease in new areas, as well as the presence of the tick vector in countries without reported cases, emphasizes the need for preventive measures to be taken. In the past, the lack of a suitable animal model susceptible to CCHFV infection has been a major obstacle in the development of vaccines and treatments. However, recent advances in biotechnology and the availability of suitable animal models have significantly expedited the development of vaccines against CCHF. These advancements have not only contributed to an enhanced understanding of the pathogenesis of CCHF but have also facilitated the evaluation of potential vaccine candidates. This review outlines the immune response to CCHFV and animal models utilized for the study of CCHFV and highlights the progress made in CCHFV vaccine studies. Despite remarkable advancements in vaccine development for CCHFV, it remains crucial to prioritize continued research, collaboration, and investment in this field.

M1/M2 macrophages and their overlaps - myth or reality?

Macrophages represent heterogeneous cell population with important roles in defence mechanisms and in homoeostasis. Tissue macrophages from diverse anatomical locations adopt distinct activation states. M1 and M2 macrophages are two polarized forms of mononuclear phagocyte in vitro differentiation with distinct phenotypic patterns and functional properties, but in vivo, there is a wide range of different macrophage phenotypes in between depending on the microenvironment and natural signals they receive. In human infections, pathogens use different strategies to combat macrophages and these strategies include shaping the macrophage polarization towards one or another phenotype. Macrophages infiltrating the tumours can affect the patient's prognosis. M2 macrophages have been shown to promote tumour growth, while M1 macrophages provide both tumour-promoting and anti-tumour properties. In autoimmune diseases, both prolonged M1 activation, as well as altered M2 function can contribute to their onset and activity. In human atherosclerotic lesions, macrophages expressing both M1 and M2 profiles have been detected as one of the potential factors affecting occurrence of cardiovascular diseases. In allergic inflammation, T2 cytokines drive macrophage polarization towards M2 profiles, which promote airway inflammation and remodelling. M1 macrophages in transplantations seem to contribute to acute rejection, while M2 macrophages promote the fibrosis of the graft. The view of pro-inflammatory M1 macrophages and M2 macrophages suppressing inflammation seems to be an oversimplification because these cells exploit very high level of plasticity and represent a large scale of different immunophenotypes with overlapping properties. In this respect, it would be more precise to describe macrophages as M1-like and M2-like.

Traditional Chinese medicine invigorating the spleen and kidney promotes HBsAg seroclearance in the mouse model

Traditional Chinese medicine (TCM) is often used as an adjuvant or alternative therapy for abnormal liver biochemistry or liver fibrosis associated with chronic hepatitis B (CHB). However, the role of TCM in HBsAg seroclearance remains unclear. We aimed at exploring the role and possible mechanisms of TCM in HBsAg seroclearance. Fifteen widely used TCM granules invigorating the spleen and kidneys were screened. C57BL/6J mice were administered daily with TCM granules by gavage for 1 week. The effect of TCM on the M1 polarization of macrophages was measured using a CD86 assay. According to the principles of formulating prescriptions, three single TCM with the most noticeable effect on M1 polarization, accompanied by two other TCM granules, were used to develop a TCM formula. The hepatitis B virus-expressing mouse model was constructed by hydrodynamic injection of the pAAV/HBV1.2 plasmid. Hepatitis B virus-expressing mice were gavaged daily with phosphate-buffered saline (PBS), TCM formula, or Codonopsis Radix, for 1 week. HBsAg, HBeAg, and hepatitis B virus DNA levels were measured. In addition, gut microbiota was profiled using 16S rDNA sequencing. Several TCM granules showed significant effects on M1 polarization. The TCM formula accelerated HBsAg seroclearance compared with the Codonopsis Radix and PBS groups. Intrahepatic M1 polarization, as indicated by flow cytometry and immunohistochemistry, was induced in the TCM formula and Codonopsis Radix groups. The abundance of Alloprevotella significantly increased in the TCM formula and Codonopsis Radix groups. These results demonstrate that the TCM formula for invigorating the spleen and kidney can accelerate HBsAg seroclearance. This effect can be attributed, at least in part, to M1 polarization of intrahepatic macrophages.

Immunometabolism changes in fibrosis: from mechanisms to therapeutic strategies

Immune cells are essential for initiating and developing the fibrotic process by releasing cytokines and growth factors that activate fibroblasts and promote extracellular matrix deposition. Immunometabolism describes how metabolic alterations affect the function of immune cells and how inflammation and immune responses regulate systemic metabolism. The disturbed immune cell function and their interactions with other cells in the tissue microenvironment lead to the origin and advancement of fibrosis. Understanding the dysregulated metabolic alterations and interactions between fibroblasts and the immune cells is critical for providing new therapeutic targets for fibrosis. This review provides an overview of recent advances in the pathophysiology of fibrosis from the immunometabolism aspect, highlighting the altered metabolic pathways in critical immune cell populations and the impact of inflammation on fibroblast metabolism during the development of fibrosis. We also discuss how this knowledge could be leveraged to develop novel therapeutic strategies for treating fibrotic diseases.

Immune microenvironment changes of liver cirrhosis: emerging role of mesenchymal stromal cells

Cirrhosis is a progressive and diffuse liver disease characterized by liver tissue fibrosis and impaired liver function. This condition is brought about by several factors, including chronic hepatitis, hepatic steatosis, alcohol abuse, and other immunological injuries. The pathogenesis of liver cirrhosis is a complex process that involves the interaction of various immune cells and cytokines, which work together to create the hepatic homeostasis imbalance in the liver. Some studies have indicated that alterations in the immune microenvironment of liver cirrhosis are closely linked to the development and prognosis of the disease. The noteworthy function of mesenchymal stem cells and their paracrine secretion lies in their ability to promote the production of cytokines, which in turn enhance the self-repairing capabilities of tissues. The objective of this review is to provide a summary of the alterations in liver homeostasis and to discuss intercellular communication within the organ. Recent research on MSCs is yielding a blueprint for cell typing and biomarker immunoregulation. Hopefully, as MSCs researches continue to progress, novel therapeutic approaches will emerge to address cirrhosis.

Persistent hepatitis B virus and HIV coinfections in dually humanized mice engrafted with human liver and immune system

Chronic hepatitis B (CHB), caused by hepatitis B virus (HBV), remains a major medical problem. HBV has a high propensity for progressing to chronicity and can result in severe liver disease, including fibrosis, cirrhosis, and hepatocellular carcinoma. CHB patients frequently present with viral coinfection, including human immunodeficiency virus type (HIV) and hepatitis delta virus. About 10% of chronic HIV carriers are also persistently infected with HBV, which can result in more exacerbated liver disease. Mechanistic studies of HBV-induced immune responses and pathogenesis, which could be significantly influenced by HIV infection, have been hampered by the scarcity of immunocompetent animal models. Here, we demonstrate that humanized mice dually engrafted with components of a human immune system and a human liver supported HBV infection, which was partially controlled by human immune cells, as evidenced by lower levels of serum viremia and HBV replication intermediates in the liver. HBV infection resulted in priming and expansion of human HLA-restricted CD8+ T cells, which acquired an activated phenotype. Notably, our dually humanized mice support persistent coinfections with HBV and HIV, which opens opportunities for analyzing immune dysregulation during HBV and HIV coinfection, and preclinical testing of novel immunotherapeutics.

Targeted viral adaptation generates a simian-tropic hepatitis B virus that infects marmoset cells

Hepatitis B virus (HBV) only infects humans and chimpanzees, posing major challenges for modeling HBV infection and chronic viral hepatitis. The major barrier in establishing HBV infection in non-human primates lies at incompatibilities between HBV and simian orthologues of the HBV receptor, sodium taurocholate co-transporting polypeptide (NTCP). Through mutagenesis analysis and screening among NTCP orthologues from Old World monkeys, New World monkeys and prosimians, we determined key residues responsible for viral binding and internalization, respectively and identified marmosets as a suitable candidate for HBV infection. Primary marmoset hepatocytes and induced pluripotent stem cell-derived hepatocyte-like cells support HBV and more efficient woolly monkey HBV (WMHBV) infection. Adapted chimeric HBV genome harboring residues 1-48 of WMHBV preS1 generated here led to a more efficient infection than wild-type HBV in primary and stem cell derived marmoset hepatocytes. Collectively, our data demonstrate that minimal targeted simianization of HBV can break the species barrier in small NHPs, paving the path for an HBV primate model.

A Comparison of Lymphoid and Myeloid Cells Derived from Human Hematopoietic Stem Cells Xenografted into NOD-Derived Mouse Strains

Humanized mice are an invaluable tool for investigating human diseases such as cancer, infectious diseases, and graft-versus-host disease (GvHD). However, it is crucial to understand the strengths and limitations of humanized mice and select the most appropriate model. In this study, we describe the development of the human lymphoid and myeloid lineages using a flow cytometric analysis in four humanized mouse models derived from NOD mice xenotransplanted with CD34⁺ fetal cord blood from a single donor. Our results showed that all murine strains sustained human immune cells within a proinflammatory environment induced by GvHD. However, the Hu-SGM3 model consistently generated higher numbers of human T cells, monocytes, dendritic cells, mast cells, and megakaryocytes, and a low number of circulating platelets showing an activated profile when compared with the other murine strains. The hu-NOG-EXL model had a similar cell development profile but a higher number of circulating platelets with an inactivated state, and the hu-NSG and hu-NCG developed low frequencies of immune cells compared with the other models. Interestingly, only the hu-SGM3 and hu-EXL models developed mast cells. In conclusion, our findings highlight the importance of selecting the appropriate humanized mouse model for specific research questions, considering the strengths and limitations of each model and the immune cell populations of interest.

A spatiotemporally controlled recombinant cccDNA mouse model for studying HBV and developing drugs against the virus

Covalently closed circular (ccc) DNA is the template for hepatitis B virus (HBV) replication. The lack of small animal models for characterizing chronic HBV infection has hampered research progress in HBV pathogenesis and drug development. Here, we generated a spatiotemporally controlled recombinant cccDNA (rcccDNA) mouse model by combining Cre/loxP-mediated DNA recombination with the liver-specific "Tet-on/Cre" system. The mouse model harbors three transgenes: a single copy of the HBV genome (integrated at the Rosa26 locus, RHBV), H11-albumin-rtTA (spatiotemporal conditional module), and (tetO)₇-Cre (tetracycline response element), and is named as RHTC mouse. By supplying the RHTC mice with doxycycline (DOX)-containing drinking water for two days, the animals generate rcccDNA in hepatocytes, and the rcccDNA supports active HBV gene expression and can maintain HBV viremia persistence for over 60 weeks. Persistent HBV gene expression induces intrahepatic inflammation, fibrosis, and dysplastic pathology, which closely mirrors the disease progression in clinical patients. Bepirovirsen, an antisense oligonucleotide (ASO) targeting all HBV RNA species, showed dose-dependent antiviral effects in the RHTC mouse model. The spatiotemporally controlled rcccDNA mouse is convenient and reliable, providing versatile small animal model for studying cccDNA-centric HBV biology as well as evaluating antiviral therapeutics.

Insights into the impact of hepatitis B virus on hepatic stellate cell activation

During chronic hepatitis B virus (HBV) infection, hepatic fibrosis is a serious pathological condition caused by virus-induced liver damage. The activation of hepatic stellate cells (HSCs) is a central event in the occurrence and progression of liver fibrosis. Although accumulating evidence has shown that HBV directly stimulates HSC activation, whether the virus infects and replicates in HSCs remains controversial. Inflammation is one of the obvious characteristics of chronic HBV infection, and it has been demonstrated that persistent inflammation has a predominant role in triggering and maintaining liver fibrosis. In particular, the regulation of HSC activation by HBV-related hepatocytes via various inflammatory modulators, including TGF-β and CTGF, in a paracrine manner has been reported. In addition to these inflammation-related molecules, several inflammatory cells are essential for the progression of HBV-associated liver fibrosis. Monocytes, macrophages, Th17 cells, NK cells, as well as NKT cells, participate in the modulation of HBV-related liver fibrosis by interacting with HSCs. This review summarizes current findings on the effects of HBV and the relevant molecular mechanisms involved in HSC activation. Because HSC activation is essential for liver fibrosis, targeting HSCs is an attractive therapeutic strategy to prevent and reverse hepatic fibrosis induced by HBV infection. Video abstract.

A novel cDNA-uPA/SCID/Rag2-/- /Jak3-/- mouse model for hepatitis virus infection and reconstruction of human immune system

Although human hepatocyte-transplanted immunodeficient mice support infection with hepatitis viruses, these mice fail to develop viral hepatitis due to the lack of an adaptive immune system. In this study, we generated new immunodeficiency cDNA-urokinase-type plasminogen activator (uPA)/SCID/Rag2-/- /Jak3-/- mice and established a mouse model with both a humanized liver and immune system. Transplantation of human hepatocytes with human leukocyte antigen (HLA)-A24 resulted in establishment of a highly replaced liver in cDNA-uPA/SCID/Rag2-/- /Jak3-/- mice. These mice were successfully infected with hepatitis B virus (HBV) and hepatitis C virus (HCV) for a prolonged period and facilitate analysis of the effect of anti-HCV drugs. Administration of peripheral blood mononuclear cells (PBMCs) obtained from an HLA-A24 donor resulted in establishment of 22.6%-81.3% human CD45-positive mononuclear cell chimerism in liver-infiltrating cells without causing graft-versus-host disease in cDNA-uPA/SCID/Rag2-/- /Jak3-/- mice without human hepatocyte transplantation. When mice were transplanted with human hepatocytes and then administered HLA-A24-positive human PBMCs, an alloimmune response between transplanted human hepatocytes and PBMCs occurred, with production of transplanted hepatocyte-specific anti-HLA antibody. In conclusion, we succeeded in establishing a humanized liver/immune system characterized by an allo-reaction between transplanted human immune cells and human liver using a novel cDNA-uPA/SCID/Rag2-/- /Jak3-/- mouse. This mouse model can be used to generate a chronic hepatitis mouse model with a human immune system with application not only to hepatitis virus virology but also to investigation of the pathology of post-transplantation liver rejection.

Transcriptomics confirm the establishment of a liver-immune dual-humanized mouse model after transplantation of a single type of human bone marrow mesenchymal stem cell

BACKGROUND AND AIMS

Human bone marrow mesenchymal stem cells (hBMSCs) are important for developing a dual-humanized mouse model to clarify disease pathogenesis. We aimed to elucidate the characteristics of hBMSC transdifferentiation into liver and immune cells.

METHODS

A single type of hBMSCs was transplanted into immunodeficient Fah-/- Rag2-/- IL-2Rγc-/- SCID (FRGS) mice with fulminant hepatic failure (FHF). Liver transcriptional data from the hBMSC-transplanted mice were analysed to identify transdifferentiation with traces of liver and immune chimerism.

RESULTS

Mice with FHF were rescued by implanted hBMSCs. Human albumin/leukocyte antigen (HLA) and CD45/HLA double-positive hepatocytes and immune cells were observed in the rescued mice during the initial 3 days. The transcriptomics analysis of liver tissues from dual-humanized mice identified two transdifferentiation phases (cellular proliferation at 1-5 days and cellular differentiation/maturation at 5-14 days) and ten cell lineages transdifferentiated from hBMSCs: human hepatocytes, cholangiocytes, stellate cells, myofibroblasts, endothelial cells and immune cells (T/B/NK/NKT/Kupffer cells). Two biological processes, hepatic metabolism and liver regeneration, were characterized in the first phase, and two additional biological processes, immune cell growth and extracellular matrix (ECM) regulation, were observed in the second phase. Immunohistochemistry verified that the ten hBMSC-derived liver and immune cells were present in the livers of dual-humanized mice.

CONCLUSIONS

A syngeneic liver-immune dual-humanized mouse model was developed by transplanting a single type of hBMSC. Four biological processes linked to the transdifferentiation and biological functions of ten human liver and immune cell lineages were identified, which may help to elucidate the molecular basis of this dual-humanized mouse model for further clarifying disease pathogenesis.

RGS7-ATF3-Tip60 Complex Promotes Hepatic Steatosis and Fibrosis by Directly Inducing TNFα

Aims: The pathophysiological mechanism(s) underlying non-alcoholic fatty liver disease (NAFLD) have yet to be fully delineated and only a single drug, peroxisome proliferator-activated receptor (PPAR) α/γ agonist saroglitazar, has been approved. Here, we sought to investigate the role of Regulator of G Protein Signaling 7 (RGS7) in hyperlipidemia-dependent hepatic dysfunction. Results: RGS7 is elevated in the livers of NAFLD patients, particularly those with severe hepatic damage, pronounced insulin resistance, and high inflammation. In the liver, RGS7 forms a unique complex with transcription factor ATF3 and histone acetyltransferase Tip60, which is implicated in NAFLD. The removal of domains is necessary for ATF3/Tip60 binding compromises RGS7-dependent reactive oxygen species generation and cell death. Hepatic RGS7 knockdown (KD) prevented ATF3/Tip60 induction, and it provided protection against fibrotic remodeling and inflammation in high-fat diet-fed mice translating to improvements in liver function. Hyperlipidemia-dependent oxidative stress and metabolic dysfunction were largely reversed in RGS7 KD mice. Interestingly, saroglitazar failed to prevent RGS7/ATF3 upregulation but it did partially restore Tip60 levels. RGS7 drives the release of particularly tumor necrosis factor α (TNFα) from isolated hepatocytes, stellate cells and its depletion reverses steatosis, oxidative stress by direct TNFα exposure. Conversely, RGS7 overexpression in the liver is sufficient to trigger oxidative stress in hepatocytes that can be mitigated via TNFα inhibition. Innovation: We discovered a novel non-canonical function for an R7RGS protein, which usually functions to regulate G protein coupled receptor (GPCR) signaling. This is the first demonstration for a functional role of RGS7 outside the retina and central nervous system. Conclusion: RGS7 represents a potential novel target for the amelioration of NAFLD. Antioxid. Redox Signal. 38, 137-159.

NAFLD and HBV interplay - related mechanisms underlying liver disease progression

Non-alcoholic fatty liver disease (NAFLD) and Hepatitis B virus infection (HBV) constitute common chronic liver diseases with worldwide distribution. NAFLD burden is expected to grow in the coming decade, especially in western countries, considering the increased incidence of diabetes and obesity. Despite the organized HBV vaccinations and use of anti-viral therapies globally, HBV infection remains endemic and challenging public health issue. As both NAFLD and HBV have been associated with the development of progressive fibrosis, cirrhosis and hepatocellular carcinoma (HCC), the co-occurrence of both diseases has gained great research and clinical interest. The causative relationship between NAFLD and HBV infection has not been elucidated so far. Dysregulated fatty acid metabolism and lipotoxicity in NAFLD disease seems to initiate activation of signaling pathways that enhance pro-inflammatory responses and disrupt hepatocyte cell homeostasis, promoting progression of NAFLD disease to NASH, fibrosis and HCC and can affect HBV replication and immune encountering of HBV virus, which may further have impact on liver disease progression. Chronic HBV infection is suggested to have an influence on metabolic changes, which could lead to NAFLD development and the HBV-induced inflammatory responses and molecular pathways may constitute an aggravating factor in hepatic steatosis development. The observed altered immune homeostasis in both HBV infection and NAFLD could be associated with progression to HCC development. Elucidation of the possible mechanisms beyond HBV chronic infection and NAFLD diseases, which could lead to advanced liver disease or increase the risk for severe complications, in the case of HBV-NAFLD co-existence is of high clinical significance in the context of designing effective therapeutic targets.

Tumor-promoting myeloid cells in the pathogenesis of human oncoviruses: potential targets for immunotherapy

Oncoviruses, known as cancer-causing viruses, are typically involved in cancer progression by inhibiting tumor suppressor pathways and uncontrolled cell division. Myeloid cells are the most frequent populations recruited to the tumor microenvironment (TME) and play a critical role in cancer development and metastasis of malignant tumors. Tumor-infiltrating myeloid cells, including tumor-associated macrophages (TAMs), myeloid-derived suppressor cells (MDSCs), tumor-associated dendritic cells (TADCs), and tumor-associated neutrophils (TANs) exert different states from anti-tumorigenic to pro-tumorigenic phenotypes in TME. Although their role in the anti-tumorigenic state is well introduced, their opposing roles, pro-tumorigenic activities, such as anti-inflammatory cytokine and reactive oxygen species (ROS) production, should not be ignored since they result in inflammation, tumor progression, angiogenesis, and evasion. Since the blockade of these cells had promising results against cancer progression, their inhibition might be helpful in various cancer immunotherapies. This review highlights the promoting role of tumor-associated myeloid cells (TAMCs) in the pathophysiology of human virus tumorigenesis.

Can next-generation humanized mice that reconstituted with both functional human immune system and hepatocytes model the progression of viral hepatitis to hepatocarcinogenesis?

Hepatitis B virus (HBV) and Hepatitis C virus (HCV) chronic infections cause liver immunopathological diseases such as hepatitis, fibrosis, cirrhosis, and hepatocellular carcinomas, which are difficult to treat and continue to be major health problems globally. Due to the species-specific hepato-tropism of HBV and HCV, conventional rodent models are limited in their utility for studying the infection and associated liver immunopathogenesis. Humanized mice reconstituted with both functional human immune system and hepatocytes (HIS-HuHEP mice) have been extremely instrumental for in vivo studies of HBV or HCV infection and human-specific aspects of the progression of liver immunopathogenesis. However, none of the current HIS-HuHEP mice can model the progression of viral hepatitis to hepatocarcinogenesis which may be a notorious result of HBV or HCV chronic infection in patients, suggesting that they were functionally compromised and that there is still significant space to improve and establish next-generation of HIS-HuHEP mice with more sophisticated functions. In this review, we first summarize the principal requirements to establish HIS-HuHEP mice. We then discuss the respective protocols for current HIS-HuHEP mice and their applications, as well as their advantages and disadvantages. We also raise perspectives for further improving and establishing next-generation HIS-HuHEP mice.

Hepatitis B Virus Infection Promotes M2 Polarization of Macrophages by Upregulating the Expression of B7x In Vivo and In Vitro

Several studies have reported that hepatitis B virus (HBV) infection is mediated by macrophages and that the B7x (B7-H4, VTCN-1) protein plays an important role in immune regulation in HBV-associated hepatocellular carcinoma (HBV-HCC). However, the relationship among HBV, macrophages, and B7x has not been studied. In this study, HBV-infected mouse model and coculture of HBV cell lines and macrophages were used to observe the changes in macrophages and the role of B7x after HBV infection. The expression of HBV markers (HBeAg, HBsAg), negative regulator of immunity (B7x), T-helper 17 (Th17)/T-regulatory (Treg)-related cytokines, and macrophage markers, as well as changes in the apoptosis and cell cycle of macrophages were analyzed through reverse transcription quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, western blot, and flow cytometry. The expression of HBsAg, HBeAg, and B7x increased and the levels of macrophage surface marker and Treg cells secrete related cytokines (IL-10 and TGF-β) were altered after HBV infection both in vivo and in vitro. Apoptosis of macrophages increased, and cell cycle arrest occurred in vitro. These effects, except those in the cell cycle, were reversed when B7x was knocked down. Thus, HBV infection can promote the expression of B7x, which in turn regulates the Th17/Treg balance and affects the expression of HBsAg and HBeAg. The mechanism used by B7x likely involves the promotion of macrophage polarization and apoptosis. These results suggest that B7x is a novel target for HBV immunotherapy.

Conversion of hepatitis B virus relaxed circular to covalently closed circular DNA is supported in murine cells

Background & Aims

HBV has a narrow host restriction, with humans and chimpanzees representing the only known natural hosts. The molecular correlates of resistance in species that are commonly used in biomedical research, such as mice, are currently incompletely understood. Expression of human NTCP (hNTCP) in mouse hepatocytes enables HBV entry, but subsequently covalently closed circular (cccDNA) does not form in most murine cells. It is unknown if this blockade in cccDNA formation is due to deficiency in repair of relaxed circular DNA (rcDNA) to cccDNA.

Methods

Here, we deployed both in vivo and in vitro virological and biochemical approaches to investigate if murine cells contain a complete set of repair factors capable of converting HBV rcDNA to cccDNA.

Results

We demonstrate that HBV cccDNA does form in murine cell culture or in mice when recombinant rcDNA without a protein adduct is directly introduced into cells. We further show that the murine orthologues of core components in DNA lagging strand synthesis, required for the repair of rcDNA to cccDNA in human cells, can support this crucial step in the HBV life cycle. It is worth noting that recombinant HBV rcDNA substrates, either without a protein adduct or containing neutravidin to mimic HBV polymerase, were used in our study; it remains unclear if the HBV polymerase removal processes are the same in mouse and human cells.

Conclusions

Collectively, our data suggest that the HBV life cycle is blocked post entry and likely before the repair stage in mouse cells, which yields critical insights that will aid in the construction of a mouse model with inbred susceptibility to HBV infection.

Lay summary

Hepatitis B virus (HBV) is only known to infect humans and chimpanzees in nature. Mouse models are often used in modeling disease pathogenesis and preclinical research to assess the efficacy and safety of interventions before they are then tested in human participants. However, because mice are not susceptible to HBV infection it is difficult to accurately model human infection (and test potential treatments) in mouse models. Herein, we have shown that mice are able to perform a key step in the HBV life cycle, tightening the net around the possible reason why HBV can not efficiently infect and replicate in mice.

Intrahepatic transcriptomics reveals gene signatures in chronic hepatitis B patients responded to interferon therapy

Chronic hepatitis B virus (HBV) infection remains a substantial public health burden worldwide. Alpha-interferon (IFNα) is one of the two currently approved therapies for chronic hepatitis B (CHB), to explore the mechanisms underlying IFNα treatment response, we investigated baseline and 24-week on-treatment intrahepatic gene expression profiles in 21 CHB patients by mRNA-seq. The data analyses demonstrated that PegIFNα treatment significantly induced antiviral responses. Responders who achieved HBV DNA loss and HBeAg or HBsAg seroconversion displayed higher fold change and larger number of up-regulated interferon-stimulated genes (ISGs). Interestingly, lower expression levels of certain ISGs were observed in responders in their baseline biopsy samples. In HBeAg+ patients, non-responders had relative higher baseline HBeAg levels than responders. More importantly, HBeAg− patients showed higher HBsAg loss rate than HBeAg+ patients. Although a greater fold change of ISGs was observed in HBeAg− patients than HBeAg+ patients, upregulation of ISGs in HBeAg+ responders exceeded HBeAg− responders. Notably, PegIFNα treatment increased monocyte and mast cell infiltration, but decreased CD8 T cell and M1 macrophage infiltration in both responders and non-responders, while B cell infiltration was increased only in responders. Moreover, co-expression analysis identified ribosomal proteins as critical players in antiviral response. The data also indicate that IFNα may influence the production of viral antigens associated with endoplasmic reticulum. Collectively, the intrahepatic transcriptome analyses in this study enriched our understanding of IFN-mediated antiviral effects in CHB patients and provided novel insights into the development of potential strategies to improve IFNα therapy.

Type I interferons and TGF-β cooperate to induce liver fibrosis during HIV-1 infection under antiretroviral therapy

Liver diseases have become a major comorbidity health concern for people living with HIV-1 (PLWH) treated with combination antiretroviral therapy (cART). To investigate if HIV-1 infection and cART interact to lead to liver diseases, humanized mice reconstituted with progenitor cells from human fetal livers were infected with HIV-1 and treated with cART. We report here that chronic HIV-1 infection with cART induced hepatitis and liver fibrosis in humanized mice, associated with accumulation of M2-like macrophages (M2LMs), elevated TGF-β, and IFN signaling in the liver. Interestingly, IFN-I and TGF-β cooperatively activated human hepatic stellate cells (HepSCs) in vitro. Mechanistically, IFN-I enhanced TGF-β-induced SMAD2/3 activation in HepSCs. Finally, blockade of IFN-I signaling reversed HIV/cART-induced liver diseases in humanized mice. Consistent with the findings in humanized mice with HIV-1 and cART, we detected elevated markers of liver injury, M2LMs, and of IFN signaling in blood specimens from PLWH compared with those of healthy individuals. These findings identify the IFN-I/M2LM/HepSC axis in HIV/cART-induced liver diseases and suggest that inhibiting IFN-I signaling or M2LM may provide a novel therapeutic strategy for treating HIV/cART-associated liver diseases in PLWH treated with antiretroviral therapy.

LncRNA MAPKAPK5_AS1 facilitates cell proliferation in hepatitis B virus -related hepatocellular carcinoma

We explored the biological role of long non-coding RNA (lncRNA) MAPKAPK5_AS1 (MAAS) and the mechanism of its differential expression in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). Differentially expressed lncRNAs in HBV-related HCC were determined using bioinformatics analysis. Gain-of-function experiments were conducted to evaluate the effect of MAAS on cell proliferation. A xenograft model was established for in vivo experiments. Dual-luciferase reporter assays, chromatin immunoprecipitation, co-immunoprecipitation, and methylated RNA immunoprecipitation were performed to elucidate the underlying molecular mechanisms. MAAS was upregulated in HBV-related HCC cancerous tissues and its high expression was closely related to the poor survival probability of patients. Functional assays revealed that MAAS overexpression facilitated the proliferation of HBV⁺HCC cells in vitro and in vivo. Mechanistically, MAAS promoted the MYC proto-oncogene (c-Myc)-induced transcriptional activation of cyclin-dependent kinase 4 (CDK4), CDK6, and S-phase kinase associated protein 2 via stabilizing c-Myc protein, thereby facilitating G1/S transition. The latter contributed to the paradoxical proliferation of HBV⁺HCC cells. Although MAAS was upregulated in HBV-related HCC cancerous tissues, it was highly expressed in M2 macrophages, a major phenotype of tumor-associated macrophages in HBV-related HCC, instead of in HBV⁺HCC cells. HBeAg, an HBV-associated antigen, further elevated the MAAS level in M2 macrophages by enhancing the methyltransferase-like 3-mediated N6-methyladenosine modification of MAAS. The increased MAAS in the M2 macrophages was then transferred to HBV⁺HCC cells through the M2 macrophage-derived exosomes, promoting cell proliferation. Our findings show that HBV⁺HCC cell-secreted HBeAg upregulates MAAS expression in M2 macrophages by affecting its m⁶A modification. The upregulated MAAS is then transferred to HBV⁺HCC cells via exosomes, facilitating the proliferation of HBV⁺HCC cells by targeting c-Myc.

Deacetylation of Notch1 by SIRT1 contributes to HBsAg- and HBeAg-mediated M2 macrophage polarization

Hepatic macrophages are involved in both pathogen clearance and immunopathogenesis. Emerging evidence demonstrates that macrophage polarization plays a critical role in hepatitis B virus (HBV)-induced immune impairment and liver pathology. However, it remains largely unknown as to how HBV infection facilitates M2 macrophage polarization. Here, a mouse HBV infection model was established by hydrodynamic injection with a vector containing 1.3-fold overlength HBV genome via the tail vein. Coculture experiments with HBV-producing HepG2.2.15 cells and macrophages were established in vitro. We found that HBV-inhibited M1 while enhancing M2 markers, which was accompanied by decreased proinflammatory tumor necrosis factor-α (TNF-α) and augmented anti-inflammatory IL-10 expression. Furthermore, both hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) secretion contributed to HBV-triggered macrophage polarization from M1 toward M2 phenotype. Mechanistically, HBsAg and HBeAg could upregulate the sirtuins 1 (SIRT1) deacetylase expression, which in turn promote deacetylation of the Notch1 intracellular domain (NICD), leading to increased Akt phosphorylation and decreased NF-κB nuclear translocation in macrophages. Our findings suggest that NICD deacetylation by SIRT1 contributes to HBsAg- and HBeAg-mediated M2 macrophage polarization, raising the possibility of targeting SIRT1/Notch1 pathway in macrophages to treat HBV immune evasion and chronic HBV infection.NEW & NOTEWORTHY This study identified a previously unrecognized molecular mechanism of HBV-mediated suppression of innate immune responses. We demonstrate that deacetylation of NICD by SIRT1 contributes to HBsAg- and HBeAg-mediated M2 macrophage polarization, which may aid in the development of new macrophage-based immunotherapy for chronic HBV infection and related diseases.

Protocol for chronic hepatitis B virus infection mouse model development by patient-derived orthotopic xenografts

Background

According to the World Health Organization, more than 250 million people worldwide are chronically infected with the hepatitis B virus, and almost 800.000 patients die annually of mediated liver disorders. Therefore, adequate biological test systems are needed that could fully simulate the course of chronic hepatitis B virus infection, including in patients with hepatocellular carcinoma.

Methods

In this study, we will assess the effectiveness of existing protocols for isolation and cultivation of primary cells derived from patients with hepatocellular carcinoma in terms of the yield of viable cells and their ability to replicate the hepatitis B virus using isolation and cultivation methods for adhesive primary cells, flow cytometry and quantitative polymerase chain reaction. Another part of our study will be devoted to evaluating the effectiveness of hepatocellular carcinoma grafting methods to obtain patient-derived heterotopic and orthotopic xenograft mouse avatars using animal X-ray irradiation and surgery procedures and in vivo fluorescent signals visualization and measurements. Our study will be completed by histological methods.

Discussion

This will be the first extensive comparative study of the main modern methods and protocols for isolation and cultivation primary hepatocellular carcinoma cells and tumor engraftment to the mice. All protocols will be optimized and characterized using the: (1) efficiency of the method for isolation cells from removed hepatocellular carcinoma in terms of their quantity and viability; (2) efficiency of the primary cell cultivation protocol in terms of the rate of monolayer formation and hepatitis B virus replication; (3) efficiency of the grafting method in terms of the growth rate and the possibility of hepatitis B virus persistence and replication in mice. The most effective methods will be recommended for use in translational biomedical research.

Modulation of Macrophage Polarization by Viruses: Turning Off/On Host Antiviral Responses

Macrophages are professional antigen-presenting cells and serve as the first line of defense against invading pathogens. Macrophages are polarized toward the proinflammatory classical (M1) or anti-inflammatory alternative (M2) phenotype upon viral infections. M1-polarized macrophages exert critical roles in antiviral responses via different mechanisms. Within the long competitive history between viruses and hosts, viruses have evolved various immune evasion strategies, inhibiting macrophage acquisition of an antiviral phenotype, impairing the antiviral responses of activated macrophages, and/or exploiting macrophage phenotypes for efficient replication. This review focuses on the sophisticated regulation of macrophage polarization utilized by viruses and is expected to provide systematic insights into the regulatory mechanisms of macrophage polarization by viruses and further facilitate the design of therapeutic targets for antivirals.

Pathogenicity and virulence of Hepatitis B virus

Hepatitis B virus (HBV) is a hepatotropic virus and an important human pathogen. There are an estimated 296 million people in the world that are chronically infected by this virus, and many of them will develop severe liver diseases including hepatitis, cirrhosis and hepatocellular carcinoma (HCC). HBV is a small DNA virus that replicates via the reverse transcription pathway. In this review, we summarize the molecular pathways that govern the replication of HBV and its interactions with host cells. We also discuss viral and non-viral factors that are associated with HBV-induced carcinogenesis and pathogenesis, as well as the role of host immune responses in HBV persistence and liver pathogenesis.

Macrophages activated by hepatitis B virus have distinct metabolic profiles and suppress the virus via IL-1β to downregulate PPARα and FOXO3

Macrophages display phenotypic plasticity and can be induced by hepatitis B virus (HBV) to undergo either M1-like pro-inflammatory or M2-like anti-inflammatory polarization. Here, we report that M1-like macrophages stimulated by HBV exhibit a strong HBV-suppressive effect, which is diminished in M2-like macrophages. Transcriptomic analysis reveals that HBV induces the expression of interleukin-1β (IL-1β) in M1-like macrophages, which display a high oxidative phosphorylation (OXPHOS) activity distinct from that of conventional M1-like macrophages. Further analysis indicates that OXPHOS attenuates the expression of IL-1β, which suppresses the expression of peroxisome proliferator-activated receptor α (PPARα) and forkhead box O3 (FOXO3) in hepatocytes to suppress HBV gene expression and replication. Moreover, multiple HBV proteins can induce the expression of IL-1β in macrophages. Our results thus indicate that macrophages can respond to HBV by producing IL-1β to suppress HBV replication. However, HBV can also metabolically reprogram macrophages to enhance OXPHOS to minimize this host antiviral response.

Liver-humanized mice: A translational strategy to study metabolic disorders

The liver is the metabolic core of the whole body. Tools commonly used to study the human liver metabolism include hepatocyte cell lines, primary human hepatocytes, and pluripotent stem cells-derived hepatocytes in vitro, and liver genetically humanized mouse model in vivo. However, none of these systems can mimic the human liver in physiological and pathological states satisfactorily. Liver-humanized mice, which are established by reconstituting mouse liver with human hepatocytes, have emerged as an attractive animal model to study drug metabolism and evaluate the therapeutic effect in "human liver" in vivo because the humanized livers greatly replicate enzymatic features of human hepatocytes. The application of liver-humanized mice in studying metabolic disorders is relatively less common due to the largely uncertain replication of metabolic profiles compared to humans. Here, we summarize the metabolic characteristics and current application of liver-humanized mouse models in metabolic disorders that have been reported in the literature, trying to evaluate the pros and cons of using liver-humanized mice as novel mouse models to study metabolic disorders.

In Vivo Mouse Models for Hepatitis B Virus Infection and Their Application

Despite the availability of effective vaccination, hepatitis B virus (HBV) infection continues to be a major challenge worldwide. Research efforts are ongoing to find an effective cure for the estimated 250 million people chronically infected by HBV in recent years. The exceptionally limited host spectrum of HBV has limited the research progress. Thus, different HBV mouse models have been developed and used for studies on infection, immune responses, pathogenesis, and antiviral therapies. However, these mouse models have great limitations as no spread of HBV infection occurs in the mouse liver and no or only very mild hepatitis is present. Thus, the suitability of these mouse models for a given issue and the interpretation of the results need to be critically assessed. This review summarizes the currently available mouse models for HBV research, including hydrodynamic injection, viral vector-mediated transfection, recombinant covalently closed circular DNA (rc-cccDNA), transgenic, and liver humanized mouse models. We systematically discuss the characteristics of each model, with the main focus on hydrodynamic injection mouse model. The usefulness and limitations of each mouse model are discussed based on the published studies. This review summarizes the facts for considerations of the use and suitability of mouse model in future HBV studies.

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

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