Altered expression of interferon-stimulated genes is strongly associated with therapeutic outcomes in hepatitis B virus infection

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.

Hepatic exosomes with declined MiR-27b-3p trigger RIG-I/TBK1 signal pathway in macrophages

BACKGROUND AND AIMS

Evidence suggests that interferon alpha (IFNα) plays an essential role in decreasing the HBsAg quantification and elevating the rate of clinical cure in chronic hepatitis B (CHB). However, the mechanisms underlying the effects of the exosomes on the expression of host genes in IFNα treatment remain unclear.

METHODS

CHB patients with IFNα treatment were divided into responders and non-responders according to the degree of HBsAg decline. Through microRNA sequencing and a series of molecular biology methods, the key microRNAs in serum exosomes associated with clinical antiviral response of Peg-IFNα treatment in nucleotide analogue-treated CHB patients were investigated. The roles of exosomal miRNAs on the IFNα signal pathway were explored in macrophages.

RESULTS

MicroRNA sequencing and RT-qPCR assays confirmed six distinctly declined miRNAs in serum exosomes of responders at week 12 compared with levels at baseline. Exosomes with declined miR27b-3p in the serum of Peg-IFNα-treated responders activated phosphorylation of interferon regulatory factor 3/7 (IRF3/7) in IFNα synthesis pathway in macrophages. However, miR27b-3p overexpression in HepAD38 cells suppressed IFNα synthesis in macrophages, resulting in insufficient ability to eliminate HBV, whereas the inhibitory effect could be blocked by inhibitors of exosomes release. Luciferase assay showed miR-27b-3p directly suppressed retinoic acid-inducible gene I (RIG-I) and TANK-binding kinase 1 (TBK1) expressions, and these effects could be abrogated in mutation experiments.

CONCLUSIONS

In IFNα treatment, exosomes with declined miR-27b-3p triggered activation of RIG-I/TBK1 signalling in macrophages against HBV. Serum exosomal miR-27-3p might represent a potential biomarker for patients with CHB.

Interleukin-17A pretreatment attenuates the anti-hepatitis B virus efficacy of interferon-alpha by reducing activation of the interferon-stimulated gene factor 3 transcriptional complex in hepatitis B virus-expressing HepG2 cells

Background

Some cytokine signaling pathways can interact with interferon (IFN)-α pathway and thus regulate cell responses to IFN-α. Levels of the pro-inflammatory cytokine interleukin-17A (IL-17A) were found to be elevated in both the peripheral blood and liver in chronic hepatitis B (CHB) patients. However, how IL-17A affects the anti-HBV activity of IFN-α remains unclear.

Methods

The effects of IL-17A on anti-HBV activity of IFN-α were evaluated in HBV-expressing HepG2 cells (HepG2-HBV1.3) with IL-17A pretreatment and IFN-α stimulation. Culture supernatant levels of HBsAg, HBeAg, and HBV DNA, or intracellular expression of HBsAg and HBcAg were detected by ELISA, real-time quantitative PCR (RT-qPCR), or western blotting (WB). The expression of canonical IFN-α signaling pathway components, including the interferon-α/β receptor (IFNAR), Janus Kinase 1 (JAK1), Tyrosine Kinase 2 (TYK2), the Interferon Stimulated Gene Factor 3 complex (ISGF3) and IFN-stimulated genes (ISGs), was also examined by RT-qPCR, Immunofluorescence or WB. The effects of IL-17A were further investigated by the suppression of the IL-17A pathway with a TRAF6 inhibitor.

Results

Compared to IFN-α stimulation alone, IL-17A pretreatment followed by IFN-α stimulation increased the levels of HBsAg, HBeAg, and HBV DNA, and decreased the levels of ISGF3 complex (phosphorylated (p)-signal transducer and activator of transcription (STAT1)/p-STAT2/IRF9) and antiviral-related ISGs (ISG15, ISG20 and Mx1). Interestingly, IL-17A pretreatment increased the expression of suppressor of cytokine signaling (SOCS) 1, SOCS3 and USP18, which were also the ISGs negatively regulating activity of ISGF3. Moreover, IFNAR1 protein expression declined more sharply in the group with IL-17A pretreatment than in the group with IFN-α stimulation alone. Blocking the IL-17A pathway reversed the effects of IL-17A on the IFN-α-induced activation of ISGF3 and anti-HBV efficacy.

Conclusions

Our results demonstrate that IL-17A pretreatment could attenuate IFN-α-induced anti-HBV activity by upregulating negative regulators of the critical transcriptional ISGF3 complex. Thus, this might be a potential target for improving response to IFN-α therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01753-x.

Exosomal lncRNA HOTTIP Mediates Antiviral Effect of Tenofovir Alafenamide (TAF) on HBV Infection

INTRODUCTION

Chronic hepatitis B (CHB) virus (HBV) infection has emerged as a global health burden affecting nearly 292 million people. Tenofovir alafenamide (TAF) is an effective treatment for CHB patients. However, the detailed mechanism underlying the antiviral activity of TAF remains unclear.

METHODS

In this study, we investigated the antiviral effect of exosomes derived from the serum of CHB patients treated with TAF (Exo-serum) and TAF-treated macrophages (MP) (Exo-MP(TAF)).

RESULTS

RNAseq analysis was also performed to determine the associated long non-coding RNAs (lncRNAs). The results demonstrated that both Exo-serum and Exo-MP(TAF) could be taken up by HepAD38 cells and exhibited potent antiviral activities, as manifested by significantly downregulating the levels of hepatitis B surface antigen, hepatitis B e antigen, HBV DNA, and covalently closed circular DNA. The antiviral effect of Exo-serum was more potent than those of TAF treatment alone. RNAseq analysis revealed that lncRNA HOTTIP was upregulated significantly in Exo-serum. Further, lncRNA HOTTIP knockdown reversed the antiviral effect of Exo-MP(TAF) on HepAD38 cells, whereas lncRNA HOTTIP knockdown exerted the opposite roles.

DISCUSSION

Taken together, these results suggest that exosomal lncRNA HOTTIP is essential for the antiviral activity of TAF and provide a novel understanding of the exosome-mediated mechanism underlying HBV infection.

APASL guidance on stopping nucleos(t)ide analogues in chronic hepatitis B patients

Chronic hepatitis B virus (HBV) infection is currently incurable. Long-term treatment with potent and safe nucleos(t)ide analogs (NAs) can reduce hepatocellular carcinoma (HCC) and cirrhosis-related complications through profound viral suppression. However, indefinite therapy raises several crucial issues with pros and cons. Because seroclearance of hepatitis B surface (HBsAg) as functional cure is not easily achievable, a finite therapy including sequential 48-week pegylated interferon therapy may provide an opportunity to facilitate HBsAg seroclearance by the rejuvenation of exhausted immune cells. However, the cost of stopping NA is the high incidence of virological relapse and surge of alanine aminotransferase (ALT) levels, which may increase the risk of adverse outcomes (e.g., decompensation, fibrosis progression, HCC, or liver-related mortality). So far, the APASL criteria to stop NA treatment is undetectable HBV DNA levels with normalization of ALT; however, this criterion for cessation of treatment is associated with various incidence rates of virological/clinical relapse and more than 40% of NA-stoppers eventually receive retreatment. A very intensive follow-up strategy and identification of low-risk patients for virological/clinical relapse by different biomarkers are the keys to stop the NA treatment safely. Recent studies suggested that decreasing HBsAg level at the end-of-treatment to < 100-200 IU/mL seems to be a useful marker for deciding when to discontinue NAs therapy. In addition, several viral and host factors have been reviewed for their potential roles in predicting clinical relapse. Finally, the APASL guidance has proposed rules to stop NA and the subsequent follow-up strategy to achieve a better prognosis after stopping NA. In general, for both HBeAg-positive and HBeAg-negative patients who have stopped treatment, these measurements should be done every 1-3 months at the minimum until 12 months.

Peg IFN-ɑ Treatment Enhanced the Inhibitory Effect of NK Cells on the Differentiation and Proliferation of CD4 +CD25 + Tregs via IFN-γ in Chronic Hepatitis B

The immunomodulatory role of natural killer (NK) cells has been recognized recently, but its effects on CD4 +CD25 + regulatory T cells (Tregs) during chronic hepatitis B (CHB) infection and treatment remain unclear. A total of 116 nucleos(t)ide analogue (NA)-treated CHB patients were included. An inverse correlation between the peripheral frequencies of NK cells and Tregs was found in NA suppressed patients following Peg IFN-ɑ-based treatment. Further, NK cells suppressed the proliferation and differentiation of Tregs through secreting IFN-γ was evidenced in the circulation of NA-treated CHB patients as well as in the liver of HBV-carrier mouse model. Additionally, the inhibition could be enhanced by Peg IFN-ɑ treatment, which was correlated to more vigorous HBV-specific T cell responses and marked reduction in HBsAg. Our study reveals a novel immunomodulatory mechanism of NK cells and provides a theoretical basis for Peg IFN-ɑ as an immunotherapy agent in treating patients with CHB.

Suppressor of cytokine signaling proteins 1 and 3 and hepatitis B virus infection

Suppressor of cytokine signaling proteins (SOCS) are cytokine pathway inhibitors that play an important role in regulating the antiviral effect of interferon (IFN). Current studies have shown that SOCS1 and SOCS3 are closely related to hepatitis B virus (HBV) infection. Inhibition or stimulation of SOCS1 and SOCS3 expression may affect the antiviral effect by regulating the production of IFN, and may also affect the pathogenicity of HBV together with other cytokines or transcription regulators. This paper mainly discusses the possible mechanisms of SOCS1 and SOCS3 in HBV infection.

Interferon-Induced Macrophage-Derived Exosomes Mediate Antiviral Activity Against Hepatitis B Virus Through miR-574-5p

BACKGROUND

Interferon alfa (IFN-α) has been proved effective in treating chronic hepatitis B (CHB), owing to its ability to suppress hepatitis B surface antigen and hepatitis B virus (HBV) covalently closed circular DNA. However, the underlying mechanisms are unclear.

METHODS

We investigated the antiviral activities of exosomes from responders and nonresponders to pegylated IFN-α (PegIFN-α) as well as the supernatants of IFN-α-treated macrophages derived from THP-1 (the human leukemia monocyte cell line). Then the expression profiles of exosomal microRNAs (miRNAs) were analyzed using miRNA sequencing. The luciferase reporter assay was used to locate the binding position of HBV genomic sequence targeted by the identified miRNA.

RESULTS

Exosomes from PegIFN-α-treated patients, particularly responders, as well as the supernatants of IFN-α-treated macrophages exhibited anti-HBV activities, as manifested by the suppression of hepatitis B surface antigen, hepatitis B e antigen, HBV DNA, and covalently closed circular DNA levels in HBV-related cell lines. PegIFN-α treatment up-regulated exosomal hsa-miR-193a-5p, hsa-miR-25-5p, and hsa-miR-574-5p, which could partially inhibit HBV replication and transcription, and hsa-miR-574-5p reduced pregenomic RNA and polymerase messenger RNA levels by binding to the 2750-2757 position of the HBV genomic sequence.

CONCLUSIONS

Exosomes can transfer IFN-α-related miRNAs from macrophages to HBV-infected hepatocytes, and they exhibit antiviral activities against HBV replication and expression.

Roadmap to functional cure of chronic hepatitis B: An expert consensus

Hepatitis B virus (HBV) infection continues to be a major public health issue worldwide. HBsAg loss is associated with functional remission and improved long-term outcome, and is considered to be a 'functional cure' (also referred to as clinical or immunologic cure) for chronic hepatitis B. This ideal goal of therapy can be achieved using optimized combination regimens with direct-acting antivirals [eg nucleos(t)ide analogues (NAs)] and immunomodulators [eg pegylated interferon alpha2a (Peg-IFN)] in selected patients with chronic hepatitis B. Among different combination therapies currently available, those with NA lead-in followed by Peg-IFN in virally suppressed patients has been demonstrated to be effective. This review provides an updated overview of the evidence supporting the use of combination therapies and summarizes expert consensus on the roadmap to attain functional cure for chronic hepatitis B patients.