Antiviral activity of interferon-stimulated gene 20, as a putative repressor binding to hepatitis B virus enhancer II and core promoter

Predictive model for HBsAg clearance rate in chronic hepatitis B patients treated with pegylated interferon α-2b for 48 weeks

BACKGROUND AND AIMS

Chronic hepatitis B (CHB) is a major global health concern. This study aims to investigate the factors influencing hepatitis B surface antigen (HBsAg) clearance in CHB patients treated with pegylated interferon α-2b (Peg-IFNα-2b) for 48 weeks and to establish a predictive model.

METHODS

This analysis is based on the "OASIS" project, a prospective real-world multicenter study in China. We included CHB patients who completed 48 weeks of Peg-IFNα-2b treatment. Patients were randomly assigned to a training set and a validation set in a ratio of approximately 4:1 by spss 26.0, and were divided into clearance and non-clearance groups based on HBsAg status at 48 weeks. Clinical data were analyzed using SPSS 26.0, employing chi-square tests for categorical data and Mann-Whitney U tests for continuous variables. Significant factors (p < 0.05) were incorporated into a binary logistic regression model to identify independent predictors of HBsAg clearance. The predictive model's performance was evaluated using ROC curve analysis.

RESULTS

We included 868 subjects, divided into the clearance group (187 cases) and the non-clearance group (681 cases). They were randomly assigned to a training set (702 cases) and a validation set (166 cases). Key predictors included female gender (OR = 1.879), lower baseline HBsAg levels (OR = 0.371), and cirrhosis (OR = 0.438). The final predictive model was: Logit(P) = 0.92 + Gender (Female) * 0.66 - HBsAg (log) * 0.96 - Cirrhosis * 0.88. ROC analysis showed an AUC of 0.80 for the training set and 0.82 for the validation set, indicating good predictive performance.

CONCLUSION

Gender, baseline HBsAg levels, and cirrhosis are significant predictors of HBsAg clearance in CHB patients after 48 weeks of Peg-IFNα-2b therapy. The developed predictive model demonstrates high accuracy and potential clinical utility.

UBR7 E3 Ligase Suppresses Interferon-β Mediated Immune Signaling by Targeting Sp110 in Hepatitis B Virus-Induced Hepatocellular Carcinoma

A newly discovered E3 ubiquitin ligase, UBR7, plays a crucial role in histone H2BK120 monoubiquitination. Here, we report a novel function of UBR7 in promoting hepatitis B virus (HBV) pathogenesis, which further leads to HBV-induced hepatocellular carcinoma (HCC). Transcriptomics analysis from HCC patients revealed the deregulation of UBR7 in cancer. Remarkably, targeting UBR7, particularly its catalytic function, led to a significant decrease in viral copy numbers. We also identified the speckled family protein Sp110 as an important substrate of UBR7. Notably, Sp110 has been previously shown to be a resident of promyelocytic leukemia nuclear bodies (PML-NBs), where it remains SUMOylated, and during HBV infection, it undergoes deSUMOylation and exits the PML body. We observed that UBR7 ubiquitinates Sp110 at critical residues within its SAND domain. Sp110 ubiquitination downregulates genes in the type I interferon response pathway. Comparative analysis of RNA-Seq from the UBR7/Sp110 knockdown data set confirmed that the IFN-β signaling pathway gets deregulated in HCC cells in the presence of HBV. Single-cell RNA-Seq analysis of patient samples further confirmed the inverse correlation between the expression of Sp110/UBR7 and the inflammation score. Notably, silencing of UBR7 induces IRF7 phosphorylation, thereby augmenting interferon (IFN)-β and the downstream interferon-stimulated genes (ISGs). Further, wild-type but not the ubiquitination-defective mutant of Sp110 could be recruited to the type I interferon response pathway genes. Our study establishes a new function of UBR7 in non-histone protein ubiquitination, promoting viral persistence, and has important implications for the development of therapeutic strategies targeting HBV-induced HCC.

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.

IFN-γ: A Crucial Player in the Fight Against HBV Infection?

About 0.8 million people die because of hepatitis B virus (HBV) infection each year. In around 5% of infected adults, the immune system is ineffective in countering HBV infection, leading to chronic hepatitis B (CHB). CHB is associated with hepatocellular carcinoma, which can lead to patient death. Unfortunately, although current treatments against CHB allow control of HBV infection, they are unable to achieve complete eradication of the virus. Cytokines of the IFN family represent part of the innate immune system and are key players in virus elimination. IFN secretion induces the expression of interferon stimulated genes, producing proteins that have antiviral properties and that are essential to cell-autonomous immunity. IFN-α is commonly used as a therapeutic approach for CHB. In addition, IFN-γ has been identified as the main IFN family member responsible for HBV eradication during acute infection. In this review, we summarize the key evidence gained from cellular or animal models of HBV replication or infection concerning the potential anti-HBV roles of IFN-γ with a particular focus on some IFN-γ-inducible genes.

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.

Emerging Therapies for Chronic Hepatitis B and the Potential for a Functional Cure

Worldwide, an estimated 296 million people are living with chronic hepatitis B virus (HBV) infection, with a significant risk of morbidity and mortality. Current therapy with pegylated interferon (Peg-IFN) and indefinite or finite therapy with nucleoside/nucleotide analogues (Nucs) are effective in HBV suppression, hepatitis resolution, and prevention of disease progression. However, few achieve hepatitis B surface antigen (HBsAg) loss (functional cure), and relapse often occurs after the end of therapy (EOT) because these agents have no direct effect on durable template: covalently closed circular DNA (cccDNA) and integrated HBV DNA. Hepatitis B surface antigen loss rate increases slightly by adding or switching to Peg-IFN in Nuc-treated patients and this loss rate greatly increases up to 39% in 5 years with finite Nuc therapy with currently available Nuc(s). For this, great effort has been made to develop novel direct-acting antivirals (DAAs) and immunomodulators. Among the DAAs, entry inhibitors and capsid assembly modulators have little effect on reducing HBsAg levels; small interfering RNA, antisense oligonucleotides, and nucleic acid polymers in combination with Peg-IFN and Nuc may reduce HBsAg levels significantly, even a rate of HBsAg loss sustained for > 24 weeks after EOT up to 40%. Novel immunomodulators, including T-cell receptor agonists, check-point inhibitors, therapeutic vaccines, and monoclonal antibodies may restore HBV-specific T-cell response but not sustained HBsAg loss. The safety issues and the durability of HBsAg loss warrant further investigation. Combining agents of different classes has the potential to enhance HBsAg loss. Compounds directly targeting cccDNA would be more effective but are still in the early stage of development. More effort is required to achieve this goal.

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.

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.

Interaction between the Hepatitis B Virus and Cellular FLIP Variants in Viral Replication and the Innate Immune System

During viral evolution and adaptation, many viruses have utilized host cellular factors and machinery as their partners. HBx, as a multifunctional viral protein encoded by the hepatitis B virus (HBV), promotes HBV replication and greatly contributes to the development of HBV-associated hepatocellular carcinoma (HCC). HBx interacts with several host factors in order to regulate HBV replication and evolve carcinogenesis. The cellular FADD-like IL-1β-converting enzyme (FLICE)-like inhibitory protein (c-FLIP) is a major factor that functions in a variety of cellular pathways and specifically in apoptosis. It has been shown that the interaction between HBx and c-FLIP determines HBV fate. In this review, we provide a comprehensive and detailed overview of the interplay between c-FLIP and HBV in various environmental circumstances. We describe strategies adapted by HBV to establish its chronic infection. We also summarize the conventional roles of c-FLIP and highlight the functional outcome of the interaction between c-FLIP and HBV or other viruses in viral replication and the innate immune system.

Hepatocyte Growth Factor-Dependent Antiviral Activity of Activated cdc42-Associated Kinase 1 Against Hepatitis B Virus

Activated cdc42-associated kinase 1 (ACK1) is a well-known non-receptor tyrosine kinase that regulates cell proliferation and growth through activation of cellular signaling pathways, including mitogen-activated protein kinase (MAPK). However, the anti-HBV activity of ACK1 has not been elucidated. This study aimed to investigate the role of ACK1 in the HBV life cycle and the mechanism underlying the anti-HBV activity of ACK1. To examine the antiviral activity of ACK1, we established HepG2-ACK1 cells stably overexpressing ACK1. The HBV life cycle, including HBeAg/HBsAg secretion, HBV DNA/transcription, and enhancer activity, was analyzed in HepG2 and HepG2-ACK1 cells with HBV replication-competent HBV 1.2mer (HBV 1.2). Finally, the anti-HBV activity of ACK1 was examined in an HBV infection system. ACK1 suppressed HBV gene expression and transcription in HepG2 and HepG2-ACK1 cells. Furthermore, ACK1 inhibited HBV replication by decreasing viral enhancer activity. ACK1 exhibited its anti-HBV activity via activation of Erk1/2, which consequently downregulated the expression of HNF4α binding to HBV enhancers. Furthermore, hepatocyte growth factor (HGF) induced ACK1 expression at an early stage. Finally, ACK1 mediated the antiviral effect of HGF in the HBV infection system. These results indicated that ACK1 induced by HGF inhibited HBV replication at the transcriptional level by activating the MAPK-HNF signaling pathway. Our findings suggest that ACK1 is a potentially novel upstream molecule of MAPK-mediated anti-HBV activity.

Identification and validation of a novel glycolysis-related gene signature for predicting the prognosis in ovarian cancer

Background

Ovarian cancer (OC) is the most lethal gynaecological tumor. Changes in glycolysis have been proven to play an important role in OC progression. We aimed to identify a novel glycolysis-related gene signature to better predict the prognosis of patients with OC.

Methods

mRNA and clinical data were obtained from The Cancer Genome Atlas (TCGA), International Cancer Genome Consortium (ICGC) and Genotype Tissue Expression (GTEx) database. The “limma” R package was used to identify glycolysis-related differentially expressed genes (DEGs). Then, a multivariate Cox proportional regression model and survival analysis were used to develop a glycolysis-related gene signature. Furthermore, the TCGA training set was divided into two internal test sets for validation, while the ICGC dataset was used as an external test set. A nomogram was constructed in the training set, and the relative proportions of 22 types of tumor-infiltrating immune cells were evaluated using the “CIBERSORT” R package. The enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were determined by single-sample gene set enrichment analysis (ssGSEA) with the “GSVA” R package. Finally, the expression and function of the unreported signature genes ISG20 and SEH1L were explored using immunohistochemistry, western blotting, qRT-PCR, proliferation, migration, invasion and xenograft tumor assays.

Results

A five-gene signature comprising ANGPTL4, PYGB, ISG20, SEH1L and IRS2 was constructed. This signature could predict prognosis independent of clinical factors. A nomogram incorporating the signature and three clinical features was constructed, and the calibration plot suggested that the nomogram could accurately predict the survival rate. According to ssGSEA, the signature was associated with KEGG pathways related to axon guidance, mTOR signalling, tight junctions, etc. The proportions of tumor-infiltrating immune cells differed significantly between the high-risk group and the low-risk group. The expression levels of ISG20 and SEH1L were lower in tumor tissues than in normal tissues. Overexpression of ISG20 or SEH1L suppressed the proliferation, migration and invasion of Caov3 cells in vitro and the growth of xenograft tumors in vivo.

Conclusion

Five glycolysis-related genes were identified and incorporated into a novel risk signature that can effectively assess the prognosis and guide the treatment of OC patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02045-0.

Intracellular interferon signalling pathways as potential regulators of covalently closed circular DNA in the treatment of chronic hepatitis B

Infection with the hepatitis B virus (HBV) is still a major global health threat as 250 million people worldwide continue to be chronically infected with the virus. While patients may be treated with nucleoside/nucleotide analogues, this only suppresses HBV titre to sub-detection levels without eliminating the persistent HBV covalently closed circular DNA (cccDNA) genome. As a result, HBV infection cannot be cured, and the virus reactivates when conditions are favorable. Interferons (IFNs) are cytokines known to induce powerful antiviral mechanisms that clear viruses from infected cells. They have been shown to induce cccDNA clearance, but their use in the treatment of HBV infection is limited as HBV-targeting immune cells are exhausted and HBV has evolved multiple mechanisms to evade and suppress IFN signalling. Thus, to fully utilize IFN-mediated intracellular mechanisms to effectively eliminate HBV, instead of direct IFN administration, novel strategies to sustain IFN-mediated anti-cccDNA and antiviral mechanisms need to be developed. This review will consolidate what is known about how IFNs act to achieve its intracellular antiviral effects and highlight the critical interferon-stimulated gene targets and effector mechanisms with potent anti-cccDNA functions. These include cccDNA degradation by APOBECs and cccDNA silencing and transcription repression by epigenetic modifications. In addition, the mechanisms that HBV employs to disrupt IFN signalling will be discussed. Drugs that have been developed or are in the pipeline for components of the IFN signalling pathway and HBV targets that detract IFN signalling mechanisms will also be identified and discussed for utility in the treatment of HBV infections. Together, these will provide useful insights into design strategies that specifically target cccDNA for the eradication of HBV.

The Functional and Antiviral Activity of Interferon Alpha-Inducible IFI6 Against Hepatitis B Virus Replication and Gene Expression

Hepatitis B virus is an enveloped DNA virus, that infects more than three hundred and sixty million people worldwide and leads to severe chronic liver diseases. Interferon-alpha inducible protein 6 (IFI6) is an IFN-stimulated gene (ISG) whose expression is highly regulated by the stimulation of type I IFN-alpha that restricts various kinds of virus infections by targeting different stages of the viral life cycle. This study aims to investigate the antiviral activity of IFI6 against HBV replication and gene expression. The IFI6 was highly induced by the stimulation of IFN-α in hepatoma cells. The overexpression of IFI6 inhibited while knockdown of IFI6 elevated replication and gene expression of HBV in HepG2 cells. Further study determined that IFI6 inhibited HBV replication by reducing EnhII/Cp of the HBV without affecting liver enriched transcription factors that have significant importance in regulating HBV enhancer activity. Furthermore, deletion mutation of EnhII/Cp and CHIP analysis revealed 100 bps (1715-1815 nt) putative sites involved in IFI6 mediated inhibition of HBV. Detailed analysis with EMSA demonstrated that 1715-1770 nt of EnhII/Cp was specifically involved in binding with IFI6 and restricted EnhII/Cp promoter activity. Moreover, IFI6 was localized mainly inside the nucleus to involve in the anti-HBV activity of IFI6. In vivo analysis based on the hydrodynamic injection of IFI6 expression plasmid along with HBV revealed significant inhibition of HBV DNA replication and gene expression. Overall, our results suggested a novel mechanism of IFI6 mediated HBV regulation that could develop potential therapeutics for efficient HBV infection treatment.

Antiviral Activity of Interferon Alpha-Inducible Protein 27 Against Hepatitis B Virus Gene Expression and Replication

Despite the availability of effective vaccines, hepatitis B virus (HBV) is still a major health issue, and approximately 350 million people have been chronically infected with HBV throughout the world. Interferons (IFNs) are the key molecules in the innate immune response that restrict several kinds of viral infections via the induction of hundreds of IFN-stimulated genes (ISGs). The objective of this study was to confirm if interferon alpha-inducible protein 27 (IFI27) as an ISG could inhibit HBV gene expression and DNA replication both in cell culture and in a mouse model. In human hepatoma cells, IFI27 was highly induced by the stimulation of IFN-alpha (IFN-α), and it potentiated the anti-HBV activity. The overexpression of IFI27 inhibited, while its silencing enhanced the HBV replication in HepG2 cell. However, the knocking out of IFI27 in HepG2 cells robustly increases the formation of viral DNA, RNA, and proteins. Detailed mechanistic analysis of the HBV genome showed that a sequence [nucleotide (nt) 1715-1815] of the EnhII/Cp promoter was solely responsible for viral inhibition. Similarly, the hydrodynamic injection of IFI27 expression constructs along with the HBV genome into mice resulted in a significant reduction in viral gene expression and DNA replication. In summary, our studies suggested that IFI27 contributed a vital role in HBV gene expression and replication and IFI27 may be a potential antiviral agent for the treatment of HBV.