Correlation between the suppressor of cytokine signaling-1 and 3 and hepatitis B virus: possible roles in the resistance to interferon treatment

Genes, inflammatory response, tolerance, and resistance to virus infections in migratory birds, bats, and rodents

Normally, the host immunological response to viral infection is coordinated to restore homeostasis and protect the individual from possible tissue damage. The two major approaches are adopted by the host to deal with the pathogen: resistance or tolerance. The nature of the responses often differs between species and between individuals of the same species. Resistance includes innate and adaptive immune responses to control virus replication. Disease tolerance relies on the immune response allowing the coexistence of infections in the host with minimal or no clinical signs, while maintaining sufficient viral replication for transmission. Here, we compared the virome of bats, rodents and migratory birds and the molecular mechanisms underlying symptomatic and asymptomatic disease progression. We also explore the influence of the host physiology and environmental influences on RNA virus expression and how it impacts on the whole brain transcriptome of seemingly healthy semipalmated sandpiper (Calidris pusilla) and spotted sandpiper (Actitis macularius). Three time points throughout the year were selected to understand the importance of longitudinal surveys in the characterization of the virome. We finally revisited evidence that upstream and downstream regulation of the inflammatory response is, respectively, associated with resistance and tolerance to viral infections.

Individual and Synergistic Anti-Coronavirus Activities of SOCS1/3 Antagonist and Interferon α1 Peptides

Suppressors of Cytokine Signaling (SOCS) are intracellular proteins that negatively regulate the induction of cytokines. Amongst these, SOCS1 and SOCS3 are particularly involved in inhibition of various interferons. Several viruses have hijacked this regulatory pathway: by inducing SOCS1and 3 early in infection, they suppress the host immune response. Within the cell, SOCS1/3 binds and inhibits tyrosine kinases, such as JAK2 and TYK2. We have developed a cell penetrating peptide from the activation loop of the tyrosine kinase, JAK2 (residues 1001-1013), denoted as pJAK2 that acts as a decoy and suppresses SOCS1 and 3 activity. This peptide thereby protects against several viruses in cell culture and mouse models. Herein, we show that treatment with pJAK2 inhibited the replication and release of the beta coronavirus HuCoV-OC43 and reduced production of the viral RNA, as measured by RT-qPCR, Western blot and by immunohistochemistry. We confirmed induction of SOCS1 and 3 in rhabdomyosarcoma (RD) cells, and this induction was suppressed by pJAK2 peptide. A peptide derived from the C-terminus of IFNα (IFNα-C) also inhibited replication of OC43. Furthermore, IFNα-C plus pJAK2 provided more potent inhibition than either peptide alone. To extend this study to a pandemic beta-coronavirus, we determined that treatment of cells with pJAK2 inhibited replication and release of SARS-CoV-2 in Calu-3 cells. We propose that these peptides offer a new approach to therapy against the rapidly evolving strains of beta-coronaviruses.

CpG Island Methylation of Suppressor of Cytokine Signaling-1 Gene Induced by HCV Is Associated With HCV-Related Hepatocellular Carcinoma

Suppressor of cytokine signaling 1 (SOCS-1) is implicated in both virus infection and carcinogenesis. This study investigated the role of HCV infection on SOCS-1 in normal and HCV-infected tissues and revealed a possible mechanism underlying HCV-induced hepatocellular carcinoma (HCC) genesis. In total, 10 HCV-HCC tissues, seven adjacent tissues, seven distal tissues, and 16 normal liver tissues were collected. SOCS-1 expression in tissue sections was detected by immunohistochemistry. After viral load was quantified, the correlation between SOCS-1 expression and viral load was analyzed in different tissues. Then, HCV replicon model was used to detect a relationship between HCV and SOCS-1. Subsequently, methylation-specific PCR (MSP) was applied to show the methylation status of SOCS-1 genes in normal tissues and HCV-replicating cell lines. A correlation between gene methylation, SOCS-1 expression, and HCV was analyzed. The lowest expression of SOCS-1 was observed in HCV-HCC tissues. Tissues with a higher HCV viral load showed lower SOCS-1 expression (p = 0.0282). Consistently, SOCS-1 mRNA and protein were lower in HCV-replicating cell lines than in uninfected ones. Furthermore, gene methylation was found in all examined tissues but higher in HCC tissues, and it is positively correlated with HCV viral load (r2 = 0.7309, p < 0.0001). HCV infection would upregulate methylation of the SOCS-1 gene in HCV-replicating cell lines. The downregulation of SOCS-1 in normal and HCV-replicating cell lines may result from HCV infection through epigenetic regulation, in which gene methylation in the CpG island of SOCS-1 promoters upon HCV infection suppresses its expression.

Suppression of Interferon-α Treatment Response by Host Negative Factors in Hepatitis B Virus Infection

Chronic hepatitis B virus (CHB) infection remains a major global public health issue for which there is still lacking effective curative treatment. Interferon-α (IFN-α) and its pegylated form have been approved as an anti-HBV drug with the advantage of antiviral activity and host immunity against HBV infection enhancement, however, IFN-α treatment failure in CHB patients is a challenging obstacle with 70% of CHB patients respond poorly to exogenous IFN-α treatment. The IFN-α treatment response is negatively regulated by both viral and host factors, and the role of viral factors has been extensively illustrated, while much less attention has been paid to host negative factors. Here, we summarized evidence of host negative regulators and parameters involved in IFN-α therapy failure, review the mechanisms responsible for these effects, and discuss the possible improvement of IFN-based therapy and the rationale of combining the inhibitors of negative regulators in achieving an HBV cure.

The role of SOCS proteins in the development of virus- induced hepatocellular carcinoma

Background

Liver cancer has become one of the most common cancers and has a high mortality rate. Hepatocellular carcinoma is one of the most common liver cancers, and its occurrence and development process are associated with chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections.

Main body

The serious consequences of chronic hepatitis virus infections are related to the viral invasion strategy. Furthermore, the viral escape mechanism has evolved during long-term struggles with the host. Studies have increasingly shown that suppressor of cytokine signaling (SOCS) proteins participate in the viral escape process. SOCS proteins play an important role in regulating cytokine signaling, particularly the Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway. Cytokines stimulate the expression of SOCS proteins, in turn, SOCS proteins inhibit cytokine signaling by blocking the JAK-STAT signaling pathway, thereby achieving homeostasis. By utilizing SOCS proteins, chronic hepatitis virus infection may destroy the host’s antiviral responses to achieve persistent infection.

Conclusions

This review provides recent knowledge regarding the role of SOCS proteins during chronic hepatitis virus infection and provides some new ideas for the future treatment of chronic hepatitis.

EGF receptor inhibitors comprehensively suppress hepatitis B virus by downregulation of STAT3 phosphorylation

Current antiviral therapy can not cure chronic hepatitis B virus (HBV) infection or eliminate the risk of hepatocellular carcinoma. The licensed epidermal growth factor receptor (EGFR) inhibitors have found to inhibit hepatitis C virus replication via downregulation of signal transducers and activators of transcription 3 (STAT3) phosphorylation. Since STAT3 is also involved in HBV replication, we further studied the anti-HBV efficacy of the EGFR inhibitors in this study. HBV-transfected HepG2.2.15 cells and HBV-infected HepG2-NTCP cells were used as cell models, and HBV replication, the syntheses of viral antigens and the magnitude of the covalently closed circular DNA (cccDNA) reservoir were used as indictors to test the anti-HBV effects of EGFR inhibitors erlotinib and gefitinib. Erlotinib inhibited HBV replication with a half-maximal inhibitory concentration of 1.05 μM. It also reduced the syntheses of viral antigens at concentrations of 2.5 μM or higher. The underlying mechanism was possibly correlated with its inhibition on STAT3 phosphorylation via up-regulation of suppressor of cytokine signaling 3. Gefitinib also inhibited HBV replication and antigen syntheses. Compared with the commonest antiviral drug entecavir, these EGFR inhibitors additionally reduced hepatitis B e antigen and erlotinib also marginally affected the cccDNA reservoir in HBV-infected HepG2-NTCP cells. Interestingly, these promising anti-HBV effects were significantly enhanced by extension of treatment duration. In conclusion, EGFR inhibitors demonstrated a comprehensive anti-HBV potential, highlighting a new strategy to cure HBV infection and suggesting animal model-related studies or clinical try in the future.

Suppressors of Cytokine Signaling and Protein Inhibitors of Activated Signal Transducer and Activator of Transcriptions As Therapeutic Targets in Flavivirus Infections

Flaviviruses cause significant human diseases putting more than 400 million people at risk annually worldwide. Because of migration and improved transportation, these viruses can be found on all continents (except Antarctica). Although a majority of the viruses are endemic in the tropics, a few [West Nile virus (WNV) and tick-borne encephalitis virus (TBEV)] have shown endemicity in Europe and North America. Currently, there are vaccines for the Yellow fever virus, Japanese encephalitis virus, and TBEV, but there is no effective vaccine and/or therapy against all other flaviviruses. Although there are intensive efforts to develop vaccines for Zika viruses, dengue viruses, and WNVs, there is the need for alternative or parallel antiviral therapeutic approaches. Suppressors of cytokine signaling (SOCS) and protein inhibitors of activated signal transducer and activator of transcription (STATs; PIAS), both regulatory proteins of the Janus kinase/STAT signaling pathway, have been explored as therapeutic targets in herpes simplex and vaccinia viruses, as well as in cancer therapy. In this review, we briefly describe the function of SOCS and PIAS and their therapeutic potential in flaviviral infections. [Figure: see text].

Exosomal Interferon-Induced Transmembrane Protein 2 Transmitted to Dendritic Cells Inhibits Interferon Alpha Pathway Activation and Blocks Anti-Hepatitis B Virus Efficacy of Exogenous Interferon Alpha

The negative regulators in the interferon (IFN) signaling pathway inhibit intrahepatic immune response, resulting in suboptimal therapeutic response to IFNα treatment in chronic hepatitis B (CHB) patients. Identifying the key negative factors and elucidating the regulating mechanism are essential for improving anti-HBV (hepatitis B virus) efficacy of IFNα. From the Gene Expression Omnibus (GEO) database, we downloaded and analyzed gene expression profiles of CHB patients with different responses to IFNα (GSE54747), and found that innate immune status was associated with the IFNα-based therapeutic response in CHB patients. Through PCR array, we found higher baseline level of IFN-induced transmembrane protein 2 (IFITM2) mRNA and lower baseline level of IFNα mRNA in peripheral blood mononuclear cells (PBMCs) of CHB patients with suboptimal response to IFNα treatment. Increased IFITM2 protein was also found in the serum of IFNα nonresponsive patients. With further experiments, we found that overexpressing IFITM2 in Huh7 cells suppressed endogenous IFNα synthesis by inhibiting phosphorylation of extracellular signal-regulated kinase (ERK), TANK-binding kinase 1 (TBK1), and interferon regulatory factor 3 (IRF3); knocking out IFITM2 enhanced activation of the endogenous IFNα synthesis pathway, exhibiting better inhibition on HBV replication. We also found that IFITM2 protein was shuttled by exosomes to dendritic cells (DCs), the main source of endogenous IFNα. Exosome-mediated transport of IFITM2 inhibited synthesis of endogenous IFNα in DCs whereas the inhibitory effect was abolished when IFITM2 was knocked out. Furthermore, we demonstrated that both palmitoylation inhibitor and mutation on 70/71 sites of IFITM2 protein influenced its incorporation into exosomes. Mutated IFITM2 protein increased the effect of IFNα against HBV. Conclusion: Exosome-mediated transport of IFITM2 to DCs inhibits IFNα pathway activation and blocks anti-HBV efficacy of exogenous IFNα. The findings provide an explanation to the suboptimal response of CHB patients to IFNα treatment.

SOCS3 genetic variants and promoter hypermethylation in patients with chronic hepatitis B

The clinical manifestations of hepatitis B viral infection (HBV) include chronic hepatitis B (CHB), liver cirrhosis (LC) and hepatocellular carcinoma (HCC). The contribution of negative regulator suppressor of cytokine signaling-3 (SOCS3) promoter variants in HBV disease and SOCS3 hypermethylation in tumor tissues were investigated The SOCS3 promoter region was screened for polymorphisms in 878 HBV patients and in 272 healthy individuals. SOCS3 promoter methylation was examined by bisulfite sequencing. SOCS3 mRNA expression was quantified in 37 tumor and adjacent non-tumor liver tissue specimens. The minor allele rs12953258A was associated with increased susceptibility to HBV infection (OR=1.3, 95%CI=1.1-1.6, adjusted P=0.03). The minor allele rs111033850C and rs12953258A were observed in increased frequencies in HCC and LC patients compared to CHB patients (HCC: OR=1.7, 95%CI=1.1-2.9, adjusted P=0.046; LC: OR=1.4, 95%CI=1.1-1.9, adjusted P=0.017, respectively). HBV patients with rs111033850CC major genotype had decreased viral load (P=0.034), whereas the rs12953258AA major genotype contributed towards increased viral load (P=0.029). Tumor tissues revealed increased hypermethylation compared to adjacent non-tumor tissues (OR=5.4; 95%CI= 1.9-17.1; P=0.001). Increased SOCS3 expression was observed in HBV infested tumor tissues than non-HBV related tumor tissues (P=0.0048). SOCS3 promoter hypermethylation was associated with relatively low mRNA expression in tumor tissues (P=0.0023). In conclusion, SOCS3 promoter variants are associated with HBV susceptibility and SOCS3 hypermethylation stimulates HCC development.

The development of hepatocarcinoma after long-term antivirus treatment of Chinese patients with chronic hepatitis B virus infection: Incidence, long-term outcomes and predictive factors

BACKGROUND

Patients with chronic hepatitis B virus (HBV) infection are at high risk for progressing to decompensated cirrhosis and hepatocellular carcinoma (HCC). Although long-term treatment with nucleos(t)ide analogues (NAs) benefits patients with chronic hepatitis B (CHB), many develop HCC. Therefore, the clinical outcomes of patients CHB who undergo long-term treatment with NAs remain to be identified. The aim of this study therefore was to evaluate the risk and predictors of patients with CHB who develop hepatitis B-induced HCC.

METHODS

We investigated 1200 patients with CHB who were treated with NAs for at least four years and evaluated the association of the variables ALT, HBsAg, HBV DNA, age and platelet count with the occurrence of HCC. We used multivariable analysis to identify independent risk factors for the development of HCC.

RESULTS

HCC developed in 153 NA-treated patients. Serum HBV DNA levels of 18.17% (218/1200) patients were>2000IU/mL. The median level of liver stiffness measurement (LSM) of all patients was 8.3±6.7kPa vs. 19.8±10.1kPa in patients with HCC. Advanced age, lower platelet counts, positive HBV DNA load, lower ALB concentration and relatively advanced liver disease were associated with an increased risk of developing HCC. Further, TGF-β and IFN-γ levels were higher and lower in patients with HCC or CHB, respectively.

CONCLUSIONS

Hepato-carcinogenesis occurred more frequently in patients with a positive HBV DNA load and relatively advanced liver disease. Therefore, it is important to administer antiviral therapy to patients with CHB before they develop HBV-related cirrhosis.

Peg-Interferon Lambda Treatment Induces Robust Innate and Adaptive Immunity in Chronic Hepatitis B Patients

IFN-lambda (IFNλ) is a member of the type III IFN family and is reported to possess anti-pathogen, anti-cancer, and immunomodulatory properties; however, there are limited data regarding its impact on host immune responses in vivo. We performed longitudinal and comprehensive immunosurveillance to assess the ability of pegylated (peg)-IFNλ to augment antiviral host immunity as part of a clinical trial assessing the efficacy of peg-IFNλ in chronic hepatitis B (CHB) patients. These patients were pretreated with directly acting antiviral therapy (entecavir) for 12 weeks with subsequent addition of peg-IFNλ for up to 32 weeks. In a subgroup of patients, the addition of peg-IFNλ provoked high serum levels of antiviral cytokine IL-18. We also observed the enhancement of natural killer cell polyfunctionality and the recovery of a pan-genotypic HBV-specific CD4⁺ T cells producing IFN-γ with maintenance of HBV-specific CD8⁺ T cell antiviral and cytotoxic activities. It was only in these patients that we observed strong virological control with reductions in both viral replication and HBV antigen levels. Here, we show for the first time that in vivo peg-IFNλ displays significant immunostimulatory properties with improvements in the main effectors mediating anti-HBV immunity. Interestingly, the maintenance in HBV-specific CD8⁺ T cells in the presence of peg-IFNλ is in contrast to previous studies showing that peg-IFNα treatment for CHB results in a detrimental effect on the functionality of this important antiviral T cell compartment.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT01204762.

Hepatitis B Virus e Antigen Activates the Suppressor of Cytokine Signaling 2 to Repress Interferon Action

Hepatitis B virus (HBV) infection causes acute hepatitis B (AHB), chronic hepatitis B (CHB), liver cirrhosis (LC), and eventually hepatocellular carcinoma (HCC). The presence of hepatitis B e antigen (HBeAg) in the serum generally indicates ongoing viral replication and disease progression. However, the mechanism by which HBeAg regulates HBV infection remains unclear. Interferons (IFNs) are pleiotropic cytokines that participate in host innate immunity. After binding to receptors, IFNs activate the JAK/STAT pathway to stimulate expression of IFN-stimulated genes (ISGs), leading to induction of antiviral responses. Here, we revealed that HBeAg represses IFN/JAK/STAT signaling to facilitate HBV replication. Initially, HBeAg stimulates the expression of suppressor of cytokine signaling 2 (SOCS2). Subsequently, SOCS2 impairs IFN/JAK/STAT signaling through reducing the stability of tyrosine kinase 2 (TYK2), downregulating the expression of type I and III IFN receptors, attenuating the phosphorylation and nucleus translocation of STAT1. Finally, SOCS2 inhibits the expression of ISGs, which leads to the repression of IFN action and facilitation of viral replication. These results demonstrate an important role of HBeAg in the regulation of IFN action, and provide a possible molecular mechanism by which HBV resists the IFN therapy and maintains persistent infection.

Suppressor of cytokine signaling 3 plays an important role in porcine circovirus type 2 subclinical infection by downregulating proinflammatory responses

Porcine circovirus type 2 (PCV2) causes porcine circovirus-associated diseases and usually evokes a subclinical infection, without any obvious symptoms, in pigs. It remains unclear how PCV2 leads to a subclinical infection. In this study, we found that peripheral blood mononuclear cells (PBMCs) from PCV2-challenged piglets with no significant clinical symptoms exhibited increased expression of suppressor of cytokine signaling (SOCS) 3, but no significant changes in the expression of the proinflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF)-α; this differed from piglets that displayed significant clinical symptoms. IL-6- and TNF-α-mediated signalings were inhibited in PBMCs from subclinical piglets. Elevated SOCS3 levels inhibited IL-6- and TNF-α-mediated NF-kappa-B inhibitor alpha degradation in PBMCs and PK-15 cells. SOCS3 production was also increased in PCV2-infected PK-15 porcine kidney cells, and IL-6 and TNF-α production that was induced by PCV2 in PK-15 cells was significantly increased when SOCS3 was silenced by a small interfering RNA. SOCS3 interacted with signal transducer and activator of transcription 3 and TNF-associated receptor-associated factor 2, suggesting mechanisms by which SOCS3 inhibits IL-6 and TNF-α signaling. We conclude that SOCS3 plays an important role in PCV2 subclinical infection by suppressing inflammatory responses in primary immune cells.