Interferon-inducible MX2 is a host restriction factor of hepatitis B virus replication

Single-cell and spatial transcriptomics reveals an anti-tumor neutrophil subgroup in microwave thermochemotherapy-treated lip cancer

Microwave thermochemotherapy (MTC) has been applied to treat lip squamous cell carcinoma (LSCC), but a deeper understanding of its therapeutic mechanisms and molecular biology is needed. To address this, we used single-cell transcriptomics (scRNA-seq) and spatial transcriptomics (ST) to highlight the pivotal role of tumor-associated neutrophils (TANs) among tumor-infiltrating immune cells and their therapeutic response to MTC. MNDA+ TANs with anti-tumor activity (N1-phenotype) are found to be abundantly infiltrated by MTC with benefit of increased blood perfusion, and these TANs are characterized by enhanced cytotoxicity, ameliorated hypoxia, and upregulated IL1B, activating T&NK cells and fibroblasts via IL1B-IL1R. In this highly anti-tumor immunogenic and hypoxia-reversed microenvironment under MTC, fibroblasts accumulated in the tumor front (TF) can recruit N1-TANs via CXCL2-CXCR2 and clear N2-TANs (pro-tumor phenotype) via CXCL12-CXCR4, which results in the aggregation of N1-TANs and extracellular matrix (ECM) deposition. In addition, we construct an N1-TANs marker, MX2, which positively correlates with better prognosis in LSCC patients, and employ deep learning techniques to predict expression of MX2 from hematoxylin-eosin (H&E)-stained images so as to conveniently guide decision making in clinical practice. Collectively, our findings demonstrate that the N1-TANs/fibroblasts defense wall formed in response to MTC effectively combat LSCC.

Sodium propionate protects against bronchopulmonary dysplasia by inhibiting IL-17-mediated apoptosis of alveolar epithelial cells

Sodium propionate (SP) has been shown to enhance alveolar growth retardation in Bronchopulmonary Dysplasia (BPD), but the mechanism remains unclear. The aim of this study is to explore the potential mechanism of SP in the treatment of BPD by utilizing animal and cell models along with bioinformation analysis. Neonatal mice were exposed to either air (21% O2) or hyperoxia (85% O2) from the first day after birth to establish the BPD model. The neonatal mice were intraperitoneally injected with normal saline (control group) or SP (500 mg/kg, SP group) from day 8 to day 14. SP significantly reduced the inflammatory condition of alveolar septal thickening, and decreased the alveolar fusion and mitigated weight loss in BPD mice. ELISA results demonstrated that SP significantly inhibited the secretion of IL-17, IL-6 and TNFα. Transcriptome analysis confirmed that IL-17 signaling pathway is closely related to the therapeutic effects of SP on BPD. In addition, MX2, MMP10, IL-11, ZMAT4 and SEC1 genes were identified as key and potential targets involved in the mechanism of SP treating BPD. Meanwhile, in mouse alveolar epithelial cells, apoptosis was induced by hyperoxia, but it was reduced following SP intervention. The expression of IL-17 pathway related genes: IL-17A, IL-6, TNFα and cox2 was decreased in hyperoxia treated cells after SP intervention. In conclusion, through transcriptome analysis, animal and cell experiments, we explored the role of sodium propionate in attenuating apoptosis in a BPD model through IL-17 pathway.

Chasing Virus Replication and Infection: PAMP-PRR Interaction Drives Type I Interferon Production, Which in Turn Activates ISG Expression and ISGylation

The innate immune response, particularly the interferon-mediated pathway, serves as the first line of defense against viral infections. During virus infection, viral pathogen-associated molecular patterns (PAMPs) are recognized by host pattern recognition receptors (PRRs), triggering downstream signaling pathways. This leads to the activation of transcription factors like IRF3, IRF7, and NF-κB, which translocate to the nucleus and induce the production of type I interferons (IFN-α and IFN-β). Once secreted, type I interferons bind to their receptors (IFNARs) on the surfaces of infected and neighboring cells, activating the JAK-STAT pathway. This results in the formation of the ISGF3 complex (composed of STAT1, STAT2, and IRF9), which translocates to the nucleus and drives the expression of interferon-stimulated genes (ISGs). Some ISGs exert antiviral effects by directly or indirectly blocking infection and replication. Among these ISGs, ISG15 plays a crucial role in the ISGylation process, a ubiquitin-like modification that tags viral and host proteins, regulating immune responses and inhibiting viral replication. However, viruses have evolved counteractive strategies to evade ISG15-mediated immunity and ISGylation. This review first outlines the PAMP-PRR-induced pathways leading to the production of cytokines and ISGs, followed by a summary of ISGylation's role in antiviral defense and viral evasion mechanisms targeting ISG15 and ISGYlation.

Altered LY6E and TRIM6 expression in PBMCs correlated with HBsAg clearance and response to Peg-IFN-α treatment in HBeAg-negative chronic hepatitis B patients

BACKGROUND

Pegylated interferon alpha (Peg-IFN-α) has the potential to eradicate hepatitis B surface antigen (HBsAg). This study aimed to investigate whether the expression levels of lymphocyte antigen 6 family member E (LY6E) and tripartite motif-containing protein 6 (TRIM6) mRNAs in peripheral blood mononuclear cells (PBMCs) of hepatitis B e antigen (HBeAg)-negative chronic hepatitis B virus (HBV) patients is associated with the response to Peg-IFN-α treatment and HBsAg clearance.

METHODS

In this prospective study, HBeAg-negative chronic HBV patients treated with Peg-IFN-α were followed for 48 weeks. The participants were classified into two groups, the virological response (VR) group and nonvirological response (NVR) group, according to the changes in HBV DNA and HBsAg levels observed at week 48 of treatment. Furthermore, these patients were divided into a serological response (SR) group and a nonserological response (NSR) group, depending on whether they exhibited a loss of serum HBsAg or evidence of seroconversion. The expression levels of LY6E and TRIM6 mRNAs in PBMCs were evaluated using real-time quantitative PCR with fluorescence detection. The diagnostic performance of LY6E and TRIM6 was assessed by analyzing the receiver operating characteristic (ROC) curve and calculating the area under the ROC curve (AUC).

RESULTS

After the treatment period, the observed VR and SR rates were 44.64% and 28.57%, respectively. Dynamic changes in LY6E and TRIM6 mRNA levels were significantly different between the VR and NVR groups and between the SR and NSR groups. Multivariate analysis revealed that TRIM6 was independently associated with VR at weeks 12 and 24 of Peg-IFN-α therapy and with SR at week 12; in addition, LY6E was independently associated with VR at week 12 and SR at week 24. At week 24, the area under the curve (AUC) for LY6E in the prediction of VR was 0.6942, and the AUC for the prediction of SR was 0.7766; at week 12, TRIM6 had AUCs of 0.7600 for the prediction of VR and 0.8469 for the prediction of SR.

CONCLUSIONS

LY6E and TRIM6 are important biomarkers for early therapeutic responses to Peg-IFN-α and HBsAg clearance.

TRIAL REGISTRATION

Registration number: 2023 - 311. Date of registration: 1 October 2023.

Chronic Hepatitis B Virus Persistence: Mechanisms and Insights

Chronic hepatitis B (CHB) virus infection can lead to severe liver diseases, including cirrhosis and hepatocellular carcinoma. The chronicity of the hepatitis B virus (HBV) occurs because of the persistence of viral covalently closed circular DNA (cccDNA) within hepatocytes. The cccDNA serves as the template for viral replication and is central to HBV, maintaining a viral reservoir within the host. Despite therapeutic advancements, eliminating cccDNA remains elusive due to its evasion of immune surveillance. This review explores the formation and maintenance of cccDNA, highlighting host factors influencing cccDNA stability and viral replication. It also discusses current treatment strategies, including interferon-based therapies and nucleoside/nucleotide analogs, which aim to suppress viral replication. Emerging therapies such as gene editing and molecular interventions hold promise for targeting cccDNA directly. Currently, research is focused on making medications that target host factors of interest to disrupt or clear the viral reservoir. However, future research should focus on innovative approaches that directly target the cccDNA minichromosome, aiming for sustained viral suppression and potentially a cure for the HBV infection.

Achieving chronic hepatitis B functional cure: Factors and potential mechanisms

Chronic hepatitis B (CHB) is a significant global health issue affecting approximately 254 million individuals worldwide. Achieving the loss of hepatitis B surface antigen (HBsAg), either with or without seroconversion to hepatitis B surface antibody (HBsAb), is regarded as a functional cure and the optimal goal for addressing CHB, and can be achieved through various approaches, including induction with nucleos(t)ide analogues (NAs), induction with pegylated interferon alpha (PegIFNα), and spontaneous clearance of HBsAg. Spontaneous clearance of HBsAg is rare, while NAs can directly inhibit HBV DNA, they are unable to act on covalently closed circular DNA (cccDNA), hence inhibiting HBsAg production or clearing HBsAg is extremely challenging. On the other hand, functional cure based on PegIFNα shows good long-term durability, but over 10 % of patients still experience relapse, mostly within 48 weeks after functional cure. Factors related to CHB functional cure with antiviral therapy are complex, including host factors, viral factors, environmental factors, etc. The integration of HBV DNA into liver cells, persistence of HBV cccDNA, insufficient B cell responses and compromised T cell function pose significant barriers to HBV clearance. Therefore, this study systematically reviewed the relevant factors and potential mechanisms influencing functional cure CHB, which can provide a basis for personalized treatment, help predict treatment outcomes and assess prognosis, and provide theoretical support for the advancement of novel treatment strategies and medications.

Recent updates of interferon-derived myxovirus resistance protein A as a biomarker for acute viral infection

BACKGROUND

Antibiotic resistance (AMR) remains a global public health threat with a high burden in sub-Saharan countries. The overuse of antimicrobials in the clinical setting is the main factor for the spread of antibiotic resistance. Diagnostic uncertainty in differentiating between bacterial and viral infections is the major contributor to antimicrobial overuse. The available biomarkers lack specificity in guiding clinicians to make antibiotic decisions and only estimate bacterial infection.

MAIN BODY

Myxovirus resistance (Mx) proteins are a type of interferon (IFN)-inducible protein that belongs to the dynamin superfamily of large guanine triphosphates (GTPases) involved in broad antiviral responses. Myxovirus resistance protein A (MxA) is a host-derived biomarker with antiviral properties against various viruses. It is induced by IFN I and IFN III as part of the innate immune response. Its basal level is < 15 ng/ml and elevated levels are detectable 1-2 h after IFN induction and remain detectable in serum up to 10 days after viral infection. Increased levels in the blood are associated with viral infection and remain low during bacterial infections. This biomarker showed promising performance in diagnosing undifferentiated febrile patients with respiratory tract infections. In this review, we discuss the role of Mx proteins, specifically MxA, in diagnosing acute viral infections, including how they are induced and their potential as diagnostic tools.

METHODS

A comprehensive electronic search was conducted in Scopus and Medline (using the PubMed interface) regarding myxovirus resistance protein A as a biomarker for acute viral infection. In the search strategy, English language was used without date restriction. Manual search was also performed when appropriate.

CONCLUSIONS

Elevated MxA combined with other biomarkers, such as CRP and PCT, is a promising tool for identifying patients with viral infections. Therefore, incorporating MxA in the existing point of care formats help to improve the antibiotic stewardship programs and future randomized controlled trials are recommended to evaluate its utility in medical practice.

Mechanisms underlying the compromised clinical efficacy of interferon in clearing HBV

Hepatitis B virus (HBV) is a hepatotropic DNA virus that can cause acute or chronic hepatitis, representing a significant global health concern. By 2019, approximately 296 million individuals were chronically infected with HBV, with 1.5 million new cases annually and 820,000 deaths due to HBV-related cirrhosis and liver cancer. Current treatments for chronic hepatitis B include nucleotide analogs (NAs) and interferons (IFNs), particularly IFN-α. NAs, such as entecavir and tenofovir, inhibit viral reverse transcription, while IFN-α exerts antiviral effects by directly suppressing viral replication, modulating viral genome epigenetics, degrading cccDNA, and activating immune responses. Despite its potential, IFN-α shows limited clinical efficacy, partly due to HBV's interference with the IFN signaling pathway. HBV encodes proteins like HBc, Pol, HBsAg, and HBx that disrupt IFN-α function. For example, HBV Pol inhibits STAT1 phosphorylation, HBsAg suppresses STAT3 phosphorylation, and HBx interferes with IFN-α efficacy through multiple mechanisms. Additionally, HBV downregulates key genes in the IFN signaling pathway, further diminishing IFN-α's antiviral effects. Understanding these interactions is crucial for improving IFN-α-based therapies. Future research may focus on overcoming HBV resistance by targeting viral proteins or optimizing IFN-α delivery. In summary, HBV's ability to resist IFN-α limits its therapeutic effectiveness, highlighting the need for new strategies to enhance treatment outcomes.

MX2 forms nucleoporin-comprising cytoplasmic biomolecular condensates that lure viral capsids

Human myxovirus resistance 2 (MX2) can restrict HIV-1 and herpesviruses at a post-entry step through a process requiring an interaction between MX2 and the viral capsids. The involvement of other host cell factors, however, remains poorly understood. Here, we mapped the proximity interactome of MX2, revealing strong enrichment of phenylalanine-glycine (FG)-rich proteins related to the nuclear pore complex as well as proteins that are part of cytoplasmic ribonucleoprotein granules. MX2 interacted with these proteins to form multiprotein cytoplasmic biomolecular condensates that were essential for its anti-HIV-1 and anti-herpes simplex virus 1 (HSV-1) activity. MX2 condensate formation required the disordered N-terminal region and MX2 dimerization. Incoming HIV-1 and HSV-1 capsids associated with MX2 at these dynamic cytoplasmic biomolecular condensates, preventing nuclear entry of their viral genomes. Thus, MX2 forms cytoplasmic condensates that likely act as nuclear pore decoys, trapping capsids and inducing premature viral genome release to interfere with nuclear targeting of HIV-1 and HSV-1.

RNF144B negatively regulates antiviral immunity by targeting MDA5 for autophagic degradation

As a RIG-I-like receptor, MDA5 plays a critical role in antiviral innate immunity by acting as a cytoplasmic double-stranded RNA sensor capable of initiating type I interferon pathways. Here, we show that RNF144B specifically interacts with MDA5 and promotes K27/K33-linked polyubiquitination of MDA5 at lysine 23 and lysine 43, which promotes autophagic degradation of MDA5 by p62. Rnf144b deficiency greatly promotes IFN production and inhibits EMCV replication in vivo. Importantly, Rnf144b-/- mice has a significantly higher overall survival rate than wild-type mice upon EMCV infection. Collectively, our results identify RNF144B as a negative regulator of innate antiviral response by targeting CARDs of MDA5 and mediating autophagic degradation of MDA5.

Restriction factors regulating human herpesvirus infections

Herpesviruses are DNA viruses and the cause of diseases ranging from mild skin conditions to severe brain diseases. Mammalian antiviral host defense comprises an array of mechanisms, including restriction factors (RFs), which block specific steps in viral replication cycles. In recent years, knowledge of RFs that contribute to controlling herpesvirus infections has expanded significantly, along with a new understanding of viral evasion mechanisms and disease pathogenesis. By integrating findings from human genetics, murine models, and cellular studies, this review provides a current view of RF control of herpesvirus infections. We also explore the regulation of RF expression, discuss the roles of RFs in diseases, and point towards their growing potential as candidate therapeutic targets.

Elimination of the hepatitis B virus: A goal, a challenge

The hepatitis B elimination is a goal proposed by the WHO to be achieved by 2030 through the adoption of synergistic measures for the prevention and chronic HBV infection treatment. Complete cure is characterized by the HBV elimination from the body and is the goal of the chronic hepatitis B treatment, which once achieved, will enable the hepatitis B elimination. This, today, has been a scientific challenge. The difficulty in achieving a complete cure is due to the indefinite maintenance of a covalently closed episomal circular DNA (cccDNA) reservoir and the maintenance and persistence of an insufficient and dysfunctional immune response in chronically infected patients. Among the measures adopted to eliminate hepatitis B, two have the potential to directly interfere with the virus cycle, but with limited effect on HBV control. These are conventional vaccines-blocking transmission and antiviral therapy-inhibiting replication. Vaccines, despite their effectiveness in protecting against horizontal transmission and preventing mother-to-child vertical transmission, have no effect on chronic infection or potential to eliminate the virus. Treatment with antivirals suppresses viral replication, but has no curative effect, as it has no action against cccDNA. Therapeutic vaccines comprise an additional approach in the chronic infection treatment, however, they have only a modest effect on the immune system, enhancing it temporarily. This manuscript aims to address (1) the cccDNA persistence in the hepatocyte nucleus and the immune response dysfunction in chronically infected individuals as two primary factors that have hampered the treatment and HBV elimination from the human body; (2) the limitations of antiviral therapy and therapeutic vaccines, as strategies to control hepatitis B; and (3) the possibly promising therapeutic approaches for the complete cure and elimination of hepatitis B.

The SAMHD1-MX2 axis restricts HIV-1 infection at postviral DNA synthesis

HIV-1 replication is tightly regulated in host cells, and various restriction factors have important roles in inhibiting viral replication. SAMHD1, a well-known restriction factor, suppresses HIV-1 replication by hydrolyzing intracellular dNTPs, thereby limiting the synthesis of viral cDNA in quiescent cells. In this study, we revealed an additional and distinct mechanism of SAMHD1 inhibition during the postviral cDNA synthesis stage. Using immunoprecipitation and mass spectrometry analysis, we demonstrated the interaction between SAMHD1 and MX2/MxB, an interferon-induced antiviral factor that inhibits HIV-1 cDNA nuclear import. The disruption of endogenous MX2 expression significantly weakened the ability of SAMHD1 to inhibit HIV-1. The crucial region within SAMHD1 that binds to MX2 has been identified. Notably, we found that SAMHD1 can act as a sensor that recognizes and binds to the incoming HIV-1 core, subsequently delivering it to the molecular trap formed by MX2, thereby blocking the nuclear entry of the HIV-1 core structure. SAMHD1 mutants unable to recognize the HIV-1 core showed a substantial decrease in antiviral activity. Certain mutations in HIV-1 capsids confer resistance to MX2 inhibition while maintaining susceptibility to suppression by the SAMHD1-MX2 axis. Overall, our study identifies an intriguing antiviral pattern wherein two distinct restriction factors, SAMHD1 and MX2, collaborate to establish an alternative mechanism deviating from their actions. These findings provide valuable insight into the complex immune defense networks against exogenous viral infections and have implications for the development of targeted anti-HIV therapeutics.

IMPORTANCE

In contrast to most restriction factors that directly bind to viral components to exert their antiviral effects, SAMHD1, the only known deoxynucleotide triphosphate (dNTP) hydrolase in eukaryotes, indirectly inhibits viral replication in quiescent cells by reducing the pool of dNTP substrates available for viral cDNA synthesis. Our study provides a novel perspective on the antiviral functions of SAMHD1. In addition to its role in dNTP hydrolysis, SAMHD1 cooperates with MX2 to inhibit HIV-1 nuclear import. In this process, SAMHD1 acts as a sensor for incoming HIV-1 cores, detecting and binding to them, before subsequently delivering the complex to the molecular trap formed by MX2, thereby immobilizing the virus. This study not only reveals a new antiviral pathway for SAMHD1 but also identifies a unique collaboration and interaction between two distinct restriction factors, establishing a novel line of defense against HIV-1 infection, which challenges the traditional view of restriction factors acting independently. Overall, our findings further indicate the intricate complexity of the host immune defense network and provide potential targets for promoting host antiviral immune defense.

Hepatitis B cure: Current situation and prospects

Achievement of a 'clinical cure' in chronic hepatitis B (CHB) implies sustained virological suppression and immunological control over the infection, which is the ideal treatment goal according to domestic and international CHB management guidelines. Clinical practice has shown encouraging results for specific patient cohorts using tailored treatment regimens. These regimens incorporate either nucleos(t)ide analogs, immunomodulatory agents such as pegylated interferon α, or a strategic combination of both, sequentially or concurrently administered. Despite these advancements in the clinical handling of hepatitis B, achieving a clinical cure remains elusive for a considerable subset of patients due to the number of challenges that preclude the realization of optimal treatment outcomes. These include, but are not limited to, the emergence of antiviral resistance, incomplete immune recovery, and the persistence of covalently closed circular DNA. Moreover, the variance in response to interferon therapy and the lack of definitive biomarkers for treatment cessation also contribute to the complexity of achieving a clinical cure. This article briefly overviews the current research progress and existing issues in pursuing a clinical cure for hepatitis B.

Interferon-induced MXB protein restricts vimentin-dependent viral infection

Type I interferon (IFN) inhibits a wide spectrum of viruses through stimulating the expression of antiviral proteins. As an IFN-induced protein, myxovirus resistance B (MXB) protein was reported to inhibit multiple highly pathogenic human viruses. It remains to be determined whether MXB employs a common mechanism to restrict different viruses. Here, we find that IFN alters the subcellular localization of hundreds of host proteins, and this IFN effect is partially lost upon MXB depletion. The results of our mechanistic study reveal that MXB recognizes vimentin (VIM) and recruits protein kinase B (AKT) to phosphorylate VIM at amino acid S38, which leads to reorganization of the VIM network and impairment of intracellular trafficking of virus protein complexes, hence causing a restriction of virus infection. These results highlight a new function of MXB in modulating VIM-mediated trafficking, which may lead towards a novel broad-spectrum antiviral strategy to control a large group of viruses that depend on VIM for successful replication.

Intracellular Host Restriction of Hepatitis B Virus Replication

The hepatitis B virus (HBV) infects hepatocytes and hijacks host cellular mechanisms for its replication. Host proteins can be frontline effectors of the cell's defense and restrict viral replication by impeding multiple steps during its intracellular lifecycle. This review summarizes many of the well-described restriction factors, their mechanisms of restriction, and counteractive measures of HBV, with a special focus on viral transcription. We discuss some of the limitations and knowledge gaps about the restriction factors, highlighting how these factors may be harnessed to facilitate therapeutic strategies against HBV.

Identification of Age-Related Characteristic Genes Involved in Severe COVID-19 Infection Among Elderly Patients Using Machine Learning and Immune Cell Infiltration Analysis

Elderly patients infected with severe acute respiratory syndrome coronavirus 2 are at higher risk of severe clinical manifestation, extended hospitalization, and increased mortality. Those patients are more likely to experience persistent symptoms and exacerbate the condition of basic diseases with long COVID-19 syndrome. However, the molecular mechanisms underlying severe COVID-19 in the elderly patients remain unclear. Our study aims to investigate the function of the interaction between disease-characteristic genes and immune cell infiltration in patients with severe COVID-19 infection. COVID-19 datasets (GSE164805 and GSE180594) and aging dataset (GSE69832) were obtained from the Gene Expression Omnibus database. The combined different expression genes (DEGs) were subjected to Gene Ontology (GO) functional enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Diseases Ontology functional enrichment analysis, Gene Set Enrichment Analysis, machine learning, and immune cell infiltration analysis. GO and KEGG enrichment analyses revealed that the eight DEGs (IL23A, PTGER4, PLCB1, IL1B, CXCR1, C1QB, MX2, ALOX12) were mainly involved in inflammatory mediator regulation of TRP channels, coronavirus disease-COVID-19, and cytokine activity signaling pathways. Three-degree algorithm (LASSO, SVM-RFE, KNN) and correlation analysis showed that the five DEGs up-regulated the immune cells of macrophages M0/M1, memory B cells, gamma delta T cell, dendritic cell resting, and master cell resisting. Our study identified five hallmark genes that can serve as disease-characteristic genes and target immune cells infiltrated in severe COVID-19 patients among the elderly population, which may contribute to the study of pathogenesis and the evaluation of diagnosis and prognosis in aging patients infected with severe COVID-19.

ISG12a promotes immunotherapy of HBV-associated hepatocellular carcinoma through blocking TRIM21/AKT/β-catenin/PD-L1 axis

Hepatitis B virus (HBV) infection generally elicits weak type-I interferon (IFN) immune response in hepatocytes, covering the regulatory effect of IFN-stimulated genes. In this study, low level of IFN-stimulated gene 12a (ISG12a) predicted malignant transformation and poor prognosis of HBV-associated hepatocellular carcinoma (HCC), whereas high level of ISG12a indicated active NK cell phenotypes. ISG12a interacts with TRIM21 to inhibit the phosphorylation activation of protein kinase B (PKB, also known as AKT) and β-catenin, suppressing PD-L1 expression to block PD-1/PD-L1 signaling, thereby enhancing the anticancer effect of NK cells. The suppression of PD-1-deficient NK-92 cells on HBV-associated tumors was independent of ISG12a expression, whereas the anticancer effect of PD-1-expressed NK-92 cells on HBV-associated tumors was enhanced by ISG12a and treatments of atezolizumab and nivolumab. Thus, tumor intrinsic ISG12a promotes the anticancer effect of NK cells by regulating PD-1/PD-L1 signaling, presenting the significant role of innate immunity in defending against HBV-associated HCC.

Epigenetic orchestration of the DNA damage response: Insights into the regulatory mechanisms

The DNA damage response (DDR) is a critical cellular mechanism that safeguards genome integrity and prevents the accumulation of harmful DNA lesions. Increasing evidence highlights the intersection between DDR signaling and epigenetic regulation, offering profound insights into various aspects of cellular function including oncogenesis. This comprehensive review explores the intricate relationship between the epigenetic modifications and DDR activation, with a specific focus on the impact of viral infections. Oncogenic viruses, such as human papillomavirus, hepatitis virus (HBV or HCV), and Epstein-Barr virus have been shown to activate the DDR. Consequently, these DNA damage events trigger a cascade of epigenetic alterations, including changes in DNA methylation patterns, histone modifications and the expression of noncoding RNAs. These epigenetic changes exert profound effects on chromatin structure, gene expression, and maintenance of genome stability. Importantly, elucidation of the viral-induced epigenetic alterations in the context of DDR holds significant implications for comprehending the complexity of cancer and provides potential targets for therapeutic interventions.

miR-3188 inhibits hepatitis B virus transcription by targeting Bcl-2

Transcription of the covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) is subject to dual regulation by host factors and viral proteins. MicroRNAs (miRNAs) can regulate the expression of target genes at the post-transcriptional level. Systematic investigation of miRNA expression in HBV infection and the interaction between HBV and miRNAs may deepen our understanding of the transcription mechanisms of HBV cccDNA, thereby providing opportunities for intervention. miRNA sequencing and real-time quantitative PCR (qRT-PCR) were used to analyze miRNA expression after HBV infection of cultured cells. Clinical samples were analyzed for miRNAs and HBV transcription-related indicators, using qRT-PCR, enzyme-linked immunoassay (ELISA), and Western blot. miRNA mimics or inhibitors were used to study their effects on the HBV life cycle. The target genes of miR-3188 and their roles in HBV cccDNA transcription were also identified. The expression of 10 miRNAs, including miR-3188, which was significantly decreased after HBV infection, was measured in clinical samples from patients with chronic HBV infection. Overexpression of miR-3188 inhibited HBV transcription, whereas inhibition of miR-3188 expression promoted HBV transcription. Further investigation confirmed that miR-3188 inhibited HBV transcription by targeting Bcl-2. miR-3188 is a key miRNA that regulates HBV transcription by targeting the host protein Bcl-2. This observation provides insights into the regulation of cccDNA transcription and suggests new targets for anti-HBV treatment.

African swine fever virus pH240R enhances viral replication via inhibition of the type I IFN signaling pathway

African swine fever (ASF) is an acute, hemorrhagic, and severe infectious disease caused by ASF virus (ASFV) infection. At present, there are still no safe and effective drugs and vaccines to prevent ASF. Mining the important proteins encoded by ASFV that affect the virulence and replication of ASFV is the key to developing effective vaccines and drugs. In this study, ASFV pH240R, a capsid protein of ASFV, was found to inhibit the type I interferon (IFN) signaling pathway. Mechanistically, pH240R interacted with IFNAR1 and IFNAR2 to disrupt the interaction of IFNAR1-TYK2 and IFNAR2-JAK1. Additionally, pH240R inhibited the phosphorylation of IFNAR1, TYK2, and JAK1 induced by IFN-α, resulting in the suppression of the nuclear import of STAT1 and STAT2 and the expression of IFN-stimulated genes (ISGs). Consistent with these results, H240R-deficient ASFV (ASFV-∆H240R) infection induced more ISGs in porcine alveolar macrophages compared with its parental ASFV HLJ/18. We also found that pH240R enhanced viral replication via inhibition of ISGs expression. Taken together, our results clarify that pH240R enhances ASFV replication by inhibiting the JAK-STAT signaling pathway, which highlights the possibility of pH240R as a potential drug target.IMPORTANCEThe innate immune response is the host's first line of defense against pathogen infection, which has been reported to affect the replication and virulence of African swine fever virus (ASFV) isolates. Identification of ASFV-encoded proteins that affect the virulence and replication of ASFV is the key step in developing more effective vaccines and drugs. In this study, we found that pH240R interacted with IFNAR1 and IFNAR2 by disrupting the interaction of IFNAR1-TYK2 and IFNAR2-JAK1, resulting in the suppression of the expression of interferon (IFN)-stimulated genes (ISGs). Consistent with these results, H240R-deficient ASFV (ASFV-∆H240R) infection induces more ISGs' expression compared with its parental ASFV HLJ/18. We also found that pH240R enhanced viral replication via inhibition of ISGs' expression. Taken together, our findings showed that pH240R enhances ASFV replication by inhibiting the IFN-JAK-STAT axis, which highlights the possibility of pH240R as a potential drug target.

Mechanism of action and treatment of type I interferon in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) caused by HBV, HCV infection, and other factors is one of the most common malignancies in the world. Although, percutaneous treatments such as surgery, ethanol injection, radiofrequency ablation, and transcatheter treatments such as arterial chemoembolization are useful for local tumor control, they are not sufficient to improve the prognosis of patients with HCC. External interferon agents that induce interferon-related genes or type I interferon in combination with other drugs can reduce the recurrence rate and improve survival in HCC patients after surgery. Therefore, in this review, we focus on recent advances in the mechanism of action of type I interferons, emerging therapies, and potential therapeutic strategies for the treatment of HCC using IFNs.

Mechanism of interferon alpha therapy for chronic hepatitis B and potential approaches to improve its therapeutic efficacy

Hepatitis B virus (HBV) chronically infects 296 million people worldwide and causes more than 820,000 deaths annually due to cirrhosis and hepatocellular carcinoma. Current standard-of-care medications for chronic hepatitis B (CHB) include nucleos(t)ide analogue (NA) viral DNA polymerase inhibitors and pegylated interferon alpha (PEG-IFN-α). NAs can efficiently suppress viral replication and improve liver pathology, but not eliminate or inactivate HBV covalently closed circular DNA (cccDNA). CCC DNA is the most stable HBV replication intermediate that exists as a minichromosome in the nucleus of infected hepatocyte to transcribe viral RNA and support viral protein translation and genome replication. Consequentially, a finite duration of NA therapy rarely achieves a sustained off-treatment suppression of viral replication and life-long NA treatment is most likely required. On the contrary, PEG-IFN-α has the benefit of finite treatment duration and achieves HBsAg seroclearance, the indication of durable immune control of HBV replication and functional cure of CHB, in approximately 5% of treated patients. However, the low antiviral efficacy and poor tolerability limit its use. Understanding how IFN-α suppresses HBV replication and regulates antiviral immune responses will help rational optimization of IFN therapy and development of novel immune modulators to improve the rate of functional cure. This review article highlights mechanistic insight on IFN control of HBV infection and recent progress in development of novel IFN regimens, small molecule IFN mimetics and combination therapy of PEG-IFN-α with new direct-acting antivirals and therapeutic vaccines to facilitate the functional cure of CHB.

Hepatitis D infection induces IFN-β-mediated NK cell activation and TRAIL-dependent cytotoxicity

Background and aims

The co-infection of hepatitis B (HBV) patients with the hepatitis D virus (HDV) causes the most severe form of viral hepatitis and thus drastically worsens the course of the disease. Therapy options for HBV/HDV patients are still limited. Here, we investigated the potential of natural killer (NK) cells that are crucial drivers of the innate immune response against viruses to target HDV-infected hepatocytes.

Methods

We established in vitro co-culture models using HDV-infected hepatoma cell lines and human peripheral blood NK cells. We determined NK cell activation by flow cytometry, transcriptome analysis, bead-based cytokine immunoassays, and NK cell-mediated effects on T cells by flow cytometry. We validated the mechanisms using CRISPR/Cas9-mediated gene deletions. Moreover, we assessed the frequencies and phenotype of NK cells in peripheral blood of HBV and HDV superinfected patients.

Results

Upon co-culture with HDV-infected hepatic cell lines, NK cells upregulated activation markers, interferon-stimulated genes (ISGs) including the death receptor ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), produced interferon (IFN)-γ and eliminated HDV-infected cells via the TRAIL-TRAIL-R2 axis. We identified IFN-β released by HDV-infected cells as an important enhancer of NK cell activity. In line with our in vitro data, we observed activation of peripheral blood NK cells from HBV/HDV co-infected, but not HBV mono-infected patients.

Conclusion

Our data demonstrate NK cell activation in HDV infection and their potential to eliminate HDV-infected hepatoma cells via the TRAIL/TRAIL-R2 axis which implies a high relevance of NK cells for the design of novel anti-viral therapies.

Current Status and Challenges in Anti-Hepatitis B Virus Agents Based on Inactivation/Inhibition or Elimination of Hepatitis B Virus Covalently Closed Circular DNA

There has been over half a century since the discovery of hepatitis B virus (HBV) to now, but approximately 300 million patients with chronic hepatitis B (CHB) still live in the world, resulting in about one million deaths every year. Although currently approved antivirals (e.g., nucleoside analogues) are effective at reducing HBV replication, they have almost no impact on the existing HBV covalently closed circular DNA (cccDNA) reservoir. HBV cccDNA is a critical obstacle to the complete elimination of the virus via antiviral therapy. The true cure of HBV infection requires the eradication of viral cccDNA from HBV-infected cells; thus, the development of new agents directly or indirectly targeting HBV cccDNA is urgently needed due to the limitations of current available drugs against HBV infection. In this regard, it is the major focus of current anti-HBV research worldwide via different mechanisms to either inactivate/inhibit (functional cure) or eliminate (complete cure) HBV cccDNA. Therefore, this review discussed and summarized recent advances and challenges in efforts to inactivate/silence or eliminate viral cccDNA using anti-HBV agents from different sources, such as small molecules (including epigenetic drugs) and polypeptides/proteins, and siRNA or gene-editing approaches targeting/attenuating HBV cccDNA via different mechanisms, as well as future directions that may be considered in efforts to truly cure chronic HBV infection. In conclusion, no breakthrough has been made yet in attenuating HBV cccDNA, although a number of candidates have advanced into the phase of clinical trials. Furthermore, the overwhelming majority of the candidates function to indirectly target HBV cccDNA. No outstanding candidate directly targets HBV cccDNA. Relatively speaking, CCC_R08 and nitazoxanide may be some of the most promising agents to clear HBV infection in small molecule compounds. Additionally, CRISPR-Cas9 systems can directly target HBV cccDNA for decay and demonstrate significant anti-HBV activity. Consequently, gene-editing approaches targeting HBV cccDNA may be one of the most promising means to achieve the core goal of anti-HBV therapeutic strategies. In short, more basic studies on HBV infection need to be carried out to overcome these challenges.

IL-6 gene polymorphism predicts PEGylated IFN-α treatment response in hepatitis B surface antigen-positive chronic hepatitis B patients

Background: Genetic polymorphism can affect the response to antiviral therapy of chronic hepatitis B (CHB) patients. Objective: The study examined the genetic association of the IL-6 rs1800796 polymorphism with PEGylated IFN-α (PegIFN-α) treatment response in hepatitis B surface antigen (HBsAg)-positive CHB patients. Methods: Direct sequencing was done for the genotyping of the rs1800796 polymorphism in the serum of CHB patients. Results: More patients with combined response (n = 95) carried IL-6 rs1800796 GC genotypes, while CC genotype carriers possessed reduced HBeAg seroconversion rate and high values of hepatitis B virus DNA. Baseline HBsAg and HBeAg and IL-6 rs1800796 CC genotype were independently related to PegIFN-α treatment response. Conclusion: Detection of the IL-6 rs1800796 genotype in CHB patients may have potential guiding significance for PegIFN-α response.

Engineered anti-PDL1 with IFNα targets both immunoinhibitory and activating signals in the liver to break HBV immune tolerance

OBJECTIVE

The purpose of this study is to develop an anti-PDL1-based interferon (IFN) fusion protein to overcome the chronic hepatitis B virus (HBV)-induced immune tolerance, and combine this immunotherapy with a HBV vaccine to achieve the functional cure of chronic hepatitis B (CHB) infection.

DESIGN

We designed an anti-PDL1-IFNα heterodimeric fusion protein, in which one arm was derived from anti-PDL1 antibody and the other arm was IFNα, to allow targeted delivery of IFNα into the liver by anti-PDL1 antibody. The effect of the anti-PDL1-IFNα heterodimer on overcoming hepatitis B surface antigen (HBsAg) vaccine resistance was evaluated in chronic HBV carrier mice.

RESULTS

The anti-PDL1-IFNα heterodimer preferentially targeted the liver and resulted in viral suppression, the PD1/PDL1 immune checkpoint blockade and dendritic cell activation/antigen presentation to activate HBsAg-specific T cells, thus breaking immune tolerance in chronic HBV carrier mice. When an HBsAg vaccine was administered soon after anti-PDL1-IFNα heterodimer treatment, we observed strong anti-HBsAg antibody and HBsAg-specific T cell responses for efficient HBsAg clearance in chronic HBV carrier mice that received the combination treatment but not in those that received either single treatment.

CONCLUSIONS

Targeting the liver with an engineered anti-PDL1-IFNα heterodimer can break HBV-induced immune tolerance to an HBsAg vaccine, offering a promising translatable therapeutic strategy for the functional cure of CHB.

Circ_ATAD3B inhibits cell proliferation of breast cancer via mediating the miR-570-3p/MX2 axis

It has been discovered that some circular RNAs can serve as excellent therapeutic targets for breast cancer (BC). However, the biological role that circ ATAD3B plays in BC is not yet completely understood. As a result, the purpose of this work was to evaluate the function of circ_ATAD3B in the development of BC. Three different GEO datasets were used to compile the expression profiles of circRNAs related to BC (GSE101124, GSE165884, and GSE182471). CCK-8 and the production of clones, in addition to RT-PCR and western blot assays, were utilized in this study to evaluate the regulation of these three biological molecules in the process of BC carcinogenesis.circ_ATAD3B was the only potential BC-related circRNA that was significantly reduced in BC tumor tissues, and it functioned as a miR-570-3p sponge to suppress cell survival and proliferation, as stated by the aforementioned two algorithms. The expression of MX2 was boosted when circ_ATAD3B was used to sponge miR-570-3p. The inhibitory effect that circ_ATAD3B has on the malignant phenotype of BC cells was overcome by the expression of miR-570-3p through up-regulation and MX2 through down-regulation. The tumor suppressor circ_ATAD3B prevents cancer progression by regulating the miR-570-3p/MX2 pathway. Circ_ATAD3B may be a candidate for targeted therapy of breast cancer.

Tannic Acid Suppresses HBV Replication via the Regulation of NF-κB, MAPKs, and Autophagy in HepG2.2.15 Cells

Hepatitis B virus (HBV) infection is a serious global health problem that threatens the health of human. Tannic acid (TA), a natural polyphenol in foods, fruits, and plants, exhibits a variety of bioactive functions. In our research, we decide to explore the pharmacological mechanism of TA against HBV replication. Our results showed that TA effectively reduced the content of HBV DNA and viral antigens (HBsAg and HBeAg) in HepG2.2.15 cells. Meanwhile, TA significantly decreased the mRNA expression of HBV RNA, which include total HBV RNA, HBV pregenomic RNA, and HBV precore mRNA. Besides, TA evidently downregulated the activity of HBV promoters in HepG2.2.15 cells. Furthermore, we found that TA upregulated the expression of IL-8, TNF-α, IFN-α, and IFN-α-mediated antiviral effectors in HepG2.2.15 cells. On the contrary, TA downregulated the expression of IL-10 and hepatic nuclear factor 4 (HNF4α). In addition, TA activated the NF-κB and MAPK pathways that contributed to the inhibition of HBV replication. Finally, TA treatment led to the occurrence of autophagy, which accelerated the elimination of HBV components in HepG2.2.15 cells. Taken together, our results elucidated the suppressive effect of TA on HBV replication and provided inspiration for its clinical application in HBV treatment.

Transcriptome wide functional analysis of HBx expressing human hepatocytes stimulated with endothelial cell cross-talk

Identification of genes dysregulated during the hepatitis B virus (HBV)-host cell interaction adds to the understanding of underlying molecular mechanisms and aids in discovering effective therapies to improve prognosis in hepatitis B virus (HBV)-infected individuals. Through bioinformatics analyses of transcriptomics data, this study aimed to identify potential genes involved in the cross-talk of human hepatocytes expressing the HBV viral protein HBx with endothelial cells. Transient transfection of HBV viral gene X (HBx) was performed in THLE2 cells using pcDNA3 constructs. Through mRNA Sequencing (RNA Seq) analysis, differentially expressed genes (DEGs) were identified. THLE2 cells transfected with HBx (THLE2x) were further treated with conditioned medium from cultured human umbilical vein derived endothelial cells (HUVEC-CM). Gene Ontology (GO) enrichment analysis revealed that interferon and cytokine signaling pathways were primarily enriched for the downregulated DEGs in THLE2x cells treated with HUVEC-CM. One significant module was selected following protein-protein interaction (PPI) network generation, and thirteen hub genes were identified from the module. The prognostic values of the hub genes were evaluated using Kaplan-Meier (KM) plotter, and three genes (IRF7, IFIT1, and IFITM1) correlated with poor disease specific survival (DSS) in HCC patients with chronic hepatitis. A comparison of the DEGs identified in HUVEC-stimulated THLE2x cells with four publicly available HBV-related HCC microarray datasets revealed that PLAC8 was consistently downregulated in all four HCC datasets as well as in HUVEC-CM treated THLE2x cells. KM plots revealed that PLAC8 correlated with worse relapse free survival and progression free survival in HCC patients with hepatitis B virus infection. This study provided molecular insights which may help develop a deeper understanding of HBV-host stromal cell interaction and open avenues for future research.

Association of genetic polymorphisms in the C19orf66 gene and biochemical indices of HBV infected individuals in Yunnan

INTRODUCTION

Hepatitis B virus (HBV) infection causes serious liver diseases and is a healthy problem worldwide. Although vaccines are administered to infants after birth, there is no effective medicine for HBV infection. The interferon-stimulated genes (ISGs) are important factors in the host that can aid in restraining the virus, and the C19orf66 gene has a wide-antiviral spectrum.

METHODS

In this study, three SNPs in the C19orf66 gene were sequenced and genotyped, and their potential function were predicted and further verified by dual-luciferase reporter assay.

RESULTS

Although no significant difference of genotype and allele frequency was observed between HBV patients and the controls, the genotype and allele frequency showed significant difference between HBV patients with HBsAg-positive and HBV patients with HBsAg-negative or controls. Genotype AA (P= 0.009) and AT (P= 0.019) of rs77076061 showed higher and lower frequency in HBV patients with HBsAg-positive than in patients with HBsAg-negative, respectively. Genotype AG of rs1979262 played a risk role in HBV patients with HBsAg-positive (13.22%) than in patients with HBsAg-negative (7.53%, P= 0.036) or controls (8.48%, P= 0.033). The frequency of allele A of rs1979262 was higher in patients with HBsAg-positive (6.61%) than in patients with HBsAg-negative (3.77%, P= 0.042), while it was the opposite for the allele G. Moreover, the associations between genotypes of SNPs in the C19orf66 gene and the ALT, AST, and DBIL level were also identified. The functional assay suggested that the SNPs might influence the C19orf66 expression by changing the connection of transcriptional factors.

CONCLUSION

In summary, the association between genetic polymorphisms in the C19orf66 gene and HBV infection/biochemical indices of patients was firstly identified in Yunnan Province.

The expression of interleukin-1β in patients with chronic hepatitis B treated with pegylated-interferon-alpha combined with tenofovir disoproxil fumarate and monotherapy

BACKGROUND

Anti-hepatitis B virus (HBV) treatment uses tenofovir disoproxil fumarate (TDF) along with Pegylated-interferon-alpha (Peg-IFN-α), which is more effective than TDF/Peg-IFN-α monotherapy. We have previously shown that interleukin-1beta (IL-1β) is related to the effectiveness of IFN-α treatment in chronic hepatitis B (CHB) patients. The aim was to investigate the expression of IL-1β in CHB patients treated with Peg-IFN-α combination with TDF and TDF/Peg-IFN-α monotherapy.

METHODS

Huh7 cells infected with HBV were stimulated by Peg-IFN-α and/or Tenofovir (TFV) for 24h. A single-center cohort study of prospective recruitment of CHB patients: untreated CHB (Group A), TDF combined with Peg-IFN-α therapy (Group B), Peg-IFN-α monotherapy (Group C), TDF monotherapy (Group D). Normal donors served as controls. The clinical datas and blood of patients were collected at 0, 12, and 24 weeks. According to the early response criteria, Group B and C were divided into two subgroups: the early response group (ERG) and the non-early response group (NERG). Stimulation of HBV-infected hepatoma cells with IL-1β to validate the antiviral activity of IL-1β. To test the blood sample, cell culture supernatant, and cell lysates and to assess the expression of IL-1β and HBV replication levels in various treatment protocols, Enzyme-Linked Immunosorbent Assay (ELISA) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were used. SPSS 26.0 and GraphPad Prism 8.0.2 software were used for statistical analysis. P values < 0.05 was considered to be statistically significant.

RESULTS

In vitro experiments, Peg-IFN-α plus TFV treatment group expressed higher IL-1β and inhibited HBV more effectively than monotherapy. Finally, 162 cases were enrolled for observation (Group A (n = 45), Group B (n = 46), Group C (n = 39), and Group D (n = 32)), and normal donors (n = 20) were enrolled for control. The early virological response rates of Group B, C, and D were 58.7%, 51.3%, and 31.2%. At 24 weeks, IL-1β in Group B(P = 0.007) and C(P = 0.034) showed higher than at 0 week. In Group B, the IL-1β showed an upward trend at 12w and 24w in the ERG. IL-1β significantly reduced HBV replication levels in hepatoma cells.

CONCLUSION

The increased expression of IL-1β may enhance the efficacy of TDF combined with Peg-IFN-α therapy in achieving an early response for CHB patients.

Evolving cognition of the JAK-STAT signaling pathway: autoimmune disorders and cancer

The Janus kinase (JAK) signal transducer and activator of transcription (JAK-STAT) pathway is an evolutionarily conserved mechanism of transmembrane signal transduction that enables cells to communicate with the exterior environment. Various cytokines, interferons, growth factors, and other specific molecules activate JAK-STAT signaling to drive a series of physiological and pathological processes, including proliferation, metabolism, immune response, inflammation, and malignancy. Dysregulated JAK-STAT signaling and related genetic mutations are strongly associated with immune activation and cancer progression. Insights into the structures and functions of the JAK-STAT pathway have led to the development and approval of diverse drugs for the clinical treatment of diseases. Currently, drugs have been developed to mainly target the JAK-STAT pathway and are commonly divided into three subtypes: cytokine or receptor antibodies, JAK inhibitors, and STAT inhibitors. And novel agents also continue to be developed and tested in preclinical and clinical studies. The effectiveness and safety of each kind of drug also warrant further scientific trials before put into being clinical applications. Here, we review the current understanding of the fundamental composition and function of the JAK-STAT signaling pathway. We also discuss advancements in the understanding of JAK-STAT-related pathogenic mechanisms; targeted JAK-STAT therapies for various diseases, especially immune disorders, and cancers; newly developed JAK inhibitors; and current challenges and directions in the field.

Advancing beyond reverse transcriptase inhibitors: The new era of hepatitis B polymerase inhibitors

Hepatitis B virus (HBV) is a genetically diverse blood-borne virus responsible for chronic hepatitis B. The HBV polymerase plays a key role in viral genome replication within the human body and has been identified as a potential drug target for chronic hepatitis B therapeutics. However, available nucleotide reverse transcriptase inhibitors only target the reverse transcriptase domain of the HBV polymerase; they also pose resistance issues and require lifelong treatment that can burden patients financially. In this study, various chemical classes are reviewed that have been developed to target different domains of the HBV polymerase: Terminal protein, which plays a vital role in the formation of the viral DNA; Reverse transcriptase, which is responsible for the synthesis of the viral DNA from RNA, and; Ribonuclease H, which is responsible for degrading the RNA strand in the RNA-DNA duplex formed during the reverse transcription process. Host factors that interact with the HBV polymerase to achieve HBV replication are also reviewed; these host factors can be targeted by inhibitors to indirectly inhibit polymerase functionality. A detailed analysis of the scope and limitations of these inhibitors from a medicinal chemistry perspective is provided. The structure-activity relationship of these inhibitors and the factors that may affect their potency and selectivity are also examined. This analysis will be useful in supporting the further development of these inhibitors and in designing new inhibitors that can inhibit HBV replication more efficiently.

You Shall Not Pass: MX2 Proteins Are Versatile Viral Inhibitors

Myxovirus resistance (MX) proteins are pivotal players in the innate immune response to viral infections. Less than 10 years ago, three independent groups simultaneously showed that human MX2 is an interferon (IFN)-stimulated gene (ISG) with potent anti-human immunodeficiency virus 1 (HIV-1) activity. Thenceforth, multiple research works have been published highlighting the ability of MX2 to inhibit RNA and DNA viruses. These growing bodies of evidence have identified some of the key determinants regulating its antiviral activity. Therefore, the importance of the protein amino-terminal domain, the oligomerization state, or the ability to interact with viral components is now well recognized. Nonetheless, there are still several unknown aspects of MX2 antiviral activity asking for further research, such as the role of cellular localization or the effect of post-translational modifications. This work aims to provide a comprehensive review of our current knowledge on the molecular determinants governing the antiviral activity of this versatile ISG, using human MX2 and HIV-1 inhibition as a reference, but drawing parallelisms and noting divergent mechanisms with other proteins and viruses when necessary.

Dihydromyricetin inhibits Hepatitis B virus replication by activating NF-κB, MAPKs, and autophagy in HepG2.2.15 cells

BACKGROUND

Hepatitis B virus (HBV) infection is a severe global health problem, and there has been no effective method to eliminate HBV. This study was designed to explore the pharmacological mechanism of Dihydromyricetin (DHM) treatment on HBV replication in vitro.

METHODS AND RESULTS

DHM is a flavonoid compound from Ampelopsis grossedentata. Using HepG2.2.15 cells, which can stably express HBV in vitro, we demonstrated that DHM treatment dramatically reduced HBV replication and secretions of HBsAg and HBeAg. Meanwhile, DHM inhibited mRNA expression of HBV RNAs in HepG2.2.15 cells, including Total HBV RNA, HBV pregenomic RNA (pgRNA), and HBV precore mRNA (pcRNA). Also, DHM elevated the mRNA expressions of inflammatory cytokines and antiviral effectors. In contrast, DHM decreased the mRNA level of HNF4α, which positively correlated with HBV replication. Further studies show that the activation of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathway played a critical role in DHM-initiated inhibition of HBV replication in HepG2.2.15 cells. Besides, activated autophagy was another contributor that may accelerate the clearance of HBV components.

CONCLUSION

In summary, DHM could suppress HBV replication by activating NF-κB, MAPKs, and autophagy in HepG2.2.15 cells. Our studies shed light on the future application of DHM for the clinical treatment of HBV infection.

IFIT3 Is Increased in Serum from Patients with Chronic Hepatitis B Virus (HBV) Infection and Promotes the Anti-HBV Effect of Interferon Alpha via JAK-STAT2 In Vitro

Increasing evidence indicates that interferon alpha (IFN-α) therapy is an effective treatment option for a subgroup of patients with chronic hepatitis B virus (HBV) infection. It has been confirmed that interferon-induced protein with tetratricopeptide repeats 3 (IFIT3), a member of the interferon-stimulated genes (ISGs), could inhibit the replication of various viruses. However, its effect on HBV replication is unclear. The present study sought to explore the role and mechanism of IFIT3 in IFN-α antiviral activities against HBV. IFIT3 mRNA levels in the peripheral blood of 108 treatment-naive patients and 70 healthy controls were analyzed first. The effect of IFIT3 on the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway under the dual intervention of IFN-α and HBV was also explored in vitro. Treatment-naive individuals exhibited elevated levels of IFIT3 mRNA compared to the controls (P < 0.0001). Mechanistically, the knockdown of IFIT3 inhibited the phosphorylation of signal transducer and activator of transcription 2 (STAT2), whereas the overexpression of IFIT3 produced the opposite effect in vitro. Meanwhile, the overexpression of IFIT3 enhanced the expression of IFN-α-triggered ISGs, including myxovirus resistance A (MxA), 2'-5'-oligoadenylate synthetase 1 (OAS1), and double-stranded RNA-activated protein kinase (PKR), while a weaker induction of IFN-α-triggered ISGs was observed in ruxolitinib-treated cells. After decreasing IFIT3 expression by validated small hairpin RNAs (shRNAs), the levels of hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and HBV DNA secreted by HepG2 cells transiently transfected with the pHBV1.2 plasmid were increased. Our findings suggest that IFIT3 works in a STAT2-dependent manner to promote the antiviral effect of IFN-α through the JAK-STAT pathway in HBV infection in both human hepatocytes and hepatocarcinoma cells. IMPORTANCE Our study contributes new insights into the understanding of the functions and roles of interferon-induced protein with tetratricopeptide repeats 3 (IFIT3), which is one of the interferon-stimulated genes induced by hepatitis B virus infection in human hepatocytes and hepatocarcinoma cells, and may help to identify targeted genes promoting the efficacy of interferon alpha.

Interferon and interferon-stimulated genes in HBV treatment

Human hepatitis B virus (HBV) is a small enveloped DNA virus with a complex life cycle. It is the causative agent of acute and chronic hepatitis. HBV can resist immune system responses and often causes persistent chronic infections. HBV is the leading cause of liver cancer and cirrhosis. Interferons (IFNs) are cytokines with antiviral, immunomodulatory, and antitumor properties. IFNs are glycoproteins with a strong antiviral activity that plays an important role in adaptive and innate immune responses. They are classified into three categories (type I, II, and III) based on the structure of their cell-surface receptors. As an effective drug for controlling chronic viral infections, Type I IFNs are approved to be clinically used for the treatment of HBV infection. The therapeutic effect of interferon will be enhanced when combined with other drugs. IFNs play a biological function by inducing the expression of hundreds of IFN-stimulated genes (ISGs) in the host cells, which are responsible for the inhibiting of HBV replication, transcription, and other important processes. Animal models of HBV, such as chimpanzees, are also important tools for studying IFN treatment and ISG regulation. In the present review, we summarized the recent progress in IFN-HBV treatment and focused on its mechanism through the interaction between HBV and ISGs.

HSP90AA1 interacts with CSFV NS5A protein and regulates CSFV replication via the JAK/STAT and NF-κB signaling pathway

Classical swine fever (CSF), caused by the classical swine fever virus (CSFV), is a highly contagious and fatal viral disease, posing a significant threat to the swine industry. Heat shock protein 90 kDa alpha class A member 1 (HSP90AA1) is a very conservative chaperone protein that plays an important role in signal transduction and viral proliferation. However, the role of HSP90AA1 in CSFV infection is unknown. In this study, we found that expression of HSP90AA1 could be promoted in PK-15 and 3D4/2 cells infected by CSFV. Over-expression of HSP90AA1 could inhibit CSFV replication and functional silencing of HSP90AA1 gene promotes CSFV replication. Further exploration revealed that HSP90AA1 interacted with CSFV NS5A protein and reduced the protein levels of NS5A. Since NS5A has an important role in CSFV replication and is closely related to type I IFN and NF-κB response, we further analyzed whether HSP90AA1 affects CSFV replication by regulating type I IFN and NF-κB pathway responses. Our research found HSP90AA1 positively regulated type I IFN response by promoting STAT1 phosphorylation and nuclear translocation processes and promoted the nuclear translocation processes of p-P65. However, CSFV infection antagonizes the activation of HSP90AA1 on JAK/STAT and NF-κB pathway. In conclusion, our study found that HSP90AA1 overexpression significantly inhibited CSFV replication and may inhibit CSFV replication by interacting with NS5A and activating JAK/STAT and NF-κB signaling pathways. These results provide new insights into the mechanism of action of HSP90AA1 in CSFV infection, which abundant the candidate library of anti-CSFV.

Role of epigenetic modification in interferon treatment of hepatitis B virus infection

Human hepatitis B virus (HBV) is a small, enveloped DNA virus that causes acute and chronic hepatitis. Chronic hepatitis B (CHB) is associated with hepatocellular carcinoma pathogenesis. Interferons (IFNs) have been used for the treatment of CHB for a long time, with advantages including less treatment duration and sustained virological response. Presently, various evidence suggests that epigenetic modification of the viral covalently closed circular DNA (cccDNA) and the host genome is crucial for the regulation of viral activity. This modification includes histone acetylation, DNA methylation, N6-methyladenosine, and non-coding RNA modification. IFN treatment for CHB can stimulate multiple IFN-stimulated genes for inhibiting virus replication. IFNs can also affect the HBV life cycle through epigenetic modulation. In this review, we summarized the different mechanisms through which IFN-α inhibits HBV replication, including epigenetic regulation. Moreover, the mechanisms underlying IFN activity are discussed, which indicated its potential as a novel treatment for CHB. It is proposed that epigenetic changes such as histone acetylation, DNA methylation, m6A methylation could be the targets of IFN, which may offer a novel approach to HBV treatment.

Oncogenic viruses, cancer biology, and innate immunity

Malignancies that arise as a result of viral infection account for roughly 15% of cancer cases worldwide. The innate immune system is the body's first line of defense against oncogenic viral infection and is also involved in the response against viral-driven tumors. In this review, we discuss research advances made over the last five years elucidating how the innate immune system recognizes and responds to oncogenic viruses, how these viruses have evolved to escape this immune pressure, and ways that innate immunity can inform the development of novel therapeutics against oncogenic viral infection and their associated cancers.

Characterisation of key biomarkers in diabetic ulcers via systems bioinformatics

Diabetic ulcers (DUs) are characterised by a high incidence and disability rate. However, its pathogenesis remains elusive. Thus, a deep understanding of the underlying mechanisms for the pathogenesis of DUs has vital implications. The weighted gene co-expression network analysis was performed on the main data from the Gene Expression Omnibus database. Gene Ontology (GO) terms, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were adopted to analyse the potential biological function of the most relevant module. Furthermore, we utilised CytoHubba and protein-protein interaction network to identify the hub genes. Finally, the hub genes were validated by animal experiments in diabetic ulcer mice models. The expression of genes from the turquoise module was found to be strongly related to DUs. GO terms, KEGG analysis showed that biological functions are closely related to immune response. The hub genes included IFI35, IFIT2, MX2, OASL, RSAD2, and XAF1, which were higher in wounds of DUs mice than that in normal lesions. Additionally, we also demonstrated that the expression of hub genes was correlated with the immune response using immune checkpoint, immune cell infiltration, and immune scores. These data suggests that IFI35, IFIT2, MX2, OASL, RSAD2, and XAF1 are crucial for DUs.

Four Mx Genes Identified in Andrias davidianus and Characterization of Their Response to Chinese Giant Salamander Iridovirus Infection

Amphibians, including Andrias davidianus, are declining worldwide partly due to infectious diseases. The Myxovirus resistance (Mx) gene is a typical interferon (IFN)-stimulated gene (ISG) involved in the antiviral immunity. Therefore, knowledge regarding the antiviral immunity of A. davidianus can be used for improved reproduction in captivity and protection in the wild. In this study, we amplified and characterized four different A. davidianus Mx genes (adMx) and generated temporal mRNA expression profiles in healthy and Chinese giant salamander iridovirus (GSIV) infected A. davidianus by qualitative real-time PCR (qPCR). The four adMx genes ranged in length from 2008 to 2840 bp. The sequences revealed conserved protein domains including the dynamin superfamily signature motif and the tripartite guanosine-5-triphosphate (GTP)-binding motif. Gene and deduced amino acid sequence alignment revealed relatively high sequence identity with the Mx genes and proteins of other vertebrates. In phylogenetic analysis, the adMx genes clustered together, but also clustered closely with those of fish species. The four adMx genes were broadly expressed in healthy A. davidianus, but were differentially expressed in the spleen during the GSIV infection. Our results show that the adMx genes share major structural features with their homologs, suggesting similar functions to those in other species.

MX2: Identification and systematic mechanistic analysis of a novel immune-related biomarker for systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE) is an autoimmune disease that involves multiple organs. However, the current SLE-related biomarkers still lack sufficient sensitivity, specificity and predictive power for clinical application. Thus, it is significant to explore new immune-related biomarkers for SLE diagnosis and development.

Methods

We obtained seven SLE gene expression profile microarrays (GSE121239/11907/81622/65391/100163/45291/49454) from the GEO database. First, differentially expressed genes (DEGs) were screened using GEO2R, and SLE biomarkers were screened by performing WGCNA, Random Forest, SVM-REF, correlation with SLEDAI and differential gene analysis. Receiver operating characteristic curves (ROCs) and AUC values were used to determine the clinical value. The expression level of the biomarker was verified by RT‒qPCR. Subsequently, functional enrichment analysis was utilized to identify biomarker-associated pathways. ssGSEA, CIBERSORT, xCell and ImmuCellAI algorithms were applied to calculate the sample immune cell infiltration abundance. Single-cell data were analyzed for gene expression specificity in immune cells. Finally, the transcriptional regulatory network of the biomarker was constructed, and the corresponding therapeutic drugs were predicted.

Results

Multiple algorithms were screened together for a unique marker gene, MX2, and expression analysis of multiple datasets revealed that MX2 was highly expressed in SLE compared to the normal group (all P < 0.05), with the same trend validated by RT‒qPCR (P = 0.026). Functional enrichment analysis identified the main pathway of MX2 promotion in SLE as the NOD-like receptor signaling pathway (NES=2.492, P < 0.001, etc.). Immuno-infiltration analysis showed that MX2 was closely associated with neutrophils, and single-cell and transcriptomic data revealed that MX2 was specifically expressed in neutrophils. The NOD-like receptor signaling pathway was also remarkably correlated with neutrophils (r >0.3, P < 0.001, etc.). Most of the MX2-related interacting proteins were associated with SLE, and potential transcription factors of MX2 and its related genes were also significantly associated with the immune response.

Conclusion

Our study found that MX2 can serve as an immune-related biomarker for predicting the diagnosis and disease activity of SLE. It activates the NOD-like receptor signaling pathway and promotes neutrophil infiltration to aggravate SLE.

CK1α upregulates the IFNAR1 expression to prompt the anti-HBV effect of type I IFN in hepatoma carcinoma cells

Casein kinase 1α (CK1α) mediates the phosphorylation and degradation of interferon-α/β receptor 1 (IFNAR1) in response to viral infection. However, how CK1α regulates hepatitis B virus (HBV) replication and the anti-HBV effects of IFN-α are less reported. Here we show that CK1α can interact with IFNAR1 in hepatoma carcinoma cells and increased the abundance of IFNAR1 by reducing the ubiquitination levels in the presence of HBV. Furthermore, CK1α promotes the IFN-α triggered JAK-STAT signaling pathway and consequently enhances the antiviral effects of IFN-α against HBV replication. Our results collectively provide evidence that CK1α positively regulates the anti-HBV activity of IFN-α in hepatoma carcinoma cells, which would be a promising therapeutic target to improve the effectiveness of IFN-α therapy to cure CHB.

A 33-residue peptide tag increases solubility and stability of Escherichia coli produced single-chain antibody fragments

Single-chain variable fragments (scFvs), composed of variable domains of heavy and light chains of an antibody joined by a linker, share antigen binding capacity with their parental antibody. Due to intrinsically low solubility and stability, only two Escherichia coli-produced scFvs have been approved for therapy. Here we report that a 33-residue peptide, termed P17 tag, increases the solubility of multiple scFvs produced in Escherichia coli SHuffle strain by up to 11.6 fold. Hydrophilic sequence, especially charged residues, but not the predicted α-helical secondary structure of P17 tag, contribute to the solubility enhancement. Notably, the P17 tag elevates the thermostability of scFv as efficiently as intra-domain disulfide bonds. Moreover, a P17-tagged scFv targeting hepatitis B virus surface proteins shows over two-fold higher antigen-binding affinity and virus-neutralizing activity than the untagged version. These data strongly suggest a type I intramolecular chaperone-like activity of the P17 tag. Hence, the P17 tag could benefit the research, production, and application of scFv.

Low solubility and stability of Escherichia coli produced single chain variable fragments (scFvs) restrict their applications. Here the authors report a 33-residue peptide tag which simultaneously increases the solubility and thermostability of multiple scFvs produced in Escherichia coli SHuffle strain.

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.

MX2 Viral Substrate Breadth and Inhibitory Activity Are Regulated by Protein Phosphorylation

Human immunodeficiency virus type-1 (HIV-1) infection is potently inhibited by human myxovirus resistance 2 (MX2/MxB), which binds to the viral capsid and blocks the nuclear import of viral DNA. We have recently shown that phosphorylation is a key regulator of MX2 antiviral activity, with phosphorylation of serine residues at positions 14, 17, and 18 repressing MX2 function. Here, we extend the study of MX2 posttranslational modifications and identify serine and threonine phosphorylation in all domains of MX2. By substituting these residues with aspartic acid or alanine, hence mimicking the presence or absence of a phosphate group, respectively, we identified key positions that control MX2 antiviral activity. Aspartic acid substitutions of residues Ser306 or Thr334 and alanine substitutions of Thr343 yielded proteins with substantially reduced antiviral activity, whereas the presence of aspartic acid at positions Ser28, Thr151, or Thr343 resulted in enhanced activity: referred to as hypermorphic mutants. In some cases, these hypermorphic mutations, particularly when paired with other MX2 mutations (e.g., S28D/T151D or T151D/T343A) acquired the capacity to inhibit HIV-1 capsid mutants known to be insensitive to wild-type MX2, such as P90A or T210K, as well as MX2-resistant retroviruses such as equine infectious anemia virus (EIAV) and murine leukemia virus (MLV). This work highlights the complexity and importance of MX2 phosphorylation in the regulation of antiviral activity and in the selection of susceptible viral substrates.

Genetic polymorphisms in the IFNL4, MxA, and MxB genes were associated with biochemical index of chronic HBV patients from Yunnan, China

Hepatitis B virus (HBV) infection causes Hepatitis B, which is one of the most common causes of hepatocellular carcinoma (HCC). The single nucleotide polymorphisms (SNPs) of the host immune genes could impact HBV infection, viral clearance, and treatment effect. However, the contradictory roles of several studies suggest further analysis of various populations. The whole blood and biochemical indexes of 448 HBV patients and matched controls were collected from the Yunnan population to investigate the genetic roles of IFNL4 and the downstream genes (MxA and MxB). The genotypes, alleles, and haplotypes frequencies of the seven SNPs (rs11322783, rs117648444, rs2071430, rs17000900, rs9982944, rs408825, and rs2838029) from the HBV patients and controls were analyzed. However, no association was identified between the SNPs and HBV infection. Then, biochemical index levels were evaluated among the HBV patients with different genotypes of the seven SNPs. The results indicated that the liver function index levels (including alanine transaminase (ALT), aspartate transaminase (AST), total bilirubin (TBIL), direct bilirubin (DBIL), indirect bilirubin (IBIL), and albumin (ALB)) were influenced by the genotypes of the SNPs in HBV patients. Moreover, when the HBV patients were divided into HBsAg-positive and -negative groups, the association between the SNP genotypes and the biochemical indexes still existed. In addition, although the genetic polymorphisms in the IFNL4, MxA, and MxB genes were not significantly associated with HBV infection in the Yunnan population, these genes could indirectly influence disease progression by associating with the biochemical index levels of Yunnan HBV patients.