IFN-CSP inhibiting hepatitis B virus in HepG2.2.15 cells involves JAK-STAT signal pathway

The Spliceosome Factor EFTUD2 Promotes IFN Anti-HBV Effect through mRNA Splicing

Methods

Using a CRISPR/Cas9 gene-editing system, EFTUD2 single allele knockout HepG2.2.15 cells were constructed. Subsequently, the HBV biomarkers in EFTUD2^+/- HepG2.2.15 cells and wild-type (WT) cells with or without IFN-α treatment were detected. And the EFTUD2-regulated genes were then identified using mRNA sequence. Selected gene mRNA variants and their proteins were examined by qRT-PCR and Western blotting. To confirm the effects of EFTUD2 on HBV replication and IFN-stimulated gene (ISG) expression, a rescue experiment in EFTUD2^+/- HepG2.2.15 cells was performed by EFTUD2 overexpression.

Results

IFN-induced anti-HBV activity was found to be restricted in EFTUD2^+/- HepG2.2.15 cells. The mRNA sequence showed that EFTUD2 could regulate classical IFN and virus response genes. Mechanistically, EFTUD2 single allele knockout decreased the expression of ISG-encoded proteins, comprising Mx1, OAS1, and PKR (EIF2AK2), through mediated gene splicing. However, EFTUD2 did not affect the expression of Jak-STAT pathway genes. Furthermore, EFTUD2 overexpression could restore the attenuation of IFN anti-HBV activity and the reduction of ISG resulting from EFTUD2 single allele knockout.

Conclusion

EFTUD2, the spliceosome factor, is not IFN-inducible but is an IFN effector gene. EFTUD2 mediates IFN anti-HBV effect through regulation of gene splicing for certain ISGs, including Mx1, OAS1, and PKR. EFTUD2 does not affect IFN receptors or canonical signal transduction components. Therefore, it can be concluded that EFTUD2 regulates ISGs using a novel, nonclassical mechanism.

Lower frequency of MDSCs was significantly related to functional cure in CHB patients treated with peginterferon

BACKGROUND AND AIMS

Myeloid-derived suppressor cells (MDSCs) and CD4⁺ regulatory T cells (Tregs) expand during chronic hepatitis B virus (HBV) infection and inhibit antiviral immunity. However, the relationship between antiviral effect and the frequencies of those immune suppressive cells after pegylated interferon α-2a (PegIFNα-2a) therapy is not clearly understood. This study aimed to investigate the contribution of monocytic MDSCs (mMDSCs) and CD4⁺ Tregs to functional cure (HBsAg seroclearance) after PegIFNα-2a therapy and evaluate the effect of PegIFNα-2a therapy on these cells.

METHODS

Flow cytometry analysis was performed along with longitudinal immune monitoring of 97 hepatitis B e antigen (HBeAg) negative chronic hepatitis B (CHB) patients receiving PegIFNα-2a weekly for 48 weeks.

RESULTS

The frequencies of mMDSCs and CD4⁺ Tregs increased in all HBV patients, and they were higher in the HBsAg persistence group than in the HBsAg seroclearance group. A significant decline in the frequency of mMDSCs was found in patients who realized functional cure after PegIFNα-2a treatment. In contrast, the frequency of CD4⁺ Tregs in both the HBsAg seroclearance and persistence groups significantly increased. Multivariate analyses indicated that the baseline serum HBsAg levels (p < .001) and mMDSCs frequency (p = .027) were independently associated with the HBsAg clearance, and the combined marker (HBsAg plus mMDSCs) displayed the highest specificity (93.1%) than any other markers in predicting HBsAg seroclearance.

CONCLUSIONS

These results suggest that a poor response to PegIFNα-2a treatment in CHB patients may be related to the frequencies of immune suppressive cells, while the therapeutic targeting of these cells might be effective in boosting anti-HBV immunity.

Novel Molecular Therapeutics Targeting Signaling Pathway to Control Hepatitis B Viral Infection

Numerous canonical cellular signaling pathways modulate hepatitis B virus (HBV) replication. HBV genome products are known to play a significant role in regulating these cellular pathways for the liver’s viral-related pathology and physiology and have been identified as the main factor in hepatocarcinogenesis. Signaling changes during viral replication ultimately affect cellular persistence, multiplication, migration, genome instability, and genome damage, leading to proliferation, evasion of apoptosis, block of differentiation, and immortality. Recent studies have documented that numerous signaling pathway agonists or inhibitors play an important role in reducing HBV replication in vitro and in vivo, and some have been used in phase I or phase II clinical trials. These optional agents as molecular therapeutics target cellular pathways that could limit the replication and transcription of HBV or inhibit the secretion of the small surface antigen of HBV in a signaling-independent manner. As principle-based available information, a combined strategy including antiviral therapy and immunomodulation will be needed to control HBV infection effectively. In this review, we summarize recent findings on interventions of molecular regulators in viral replication and the interactions of HBV proteins with the components of the various targeting cellular pathways, which may assist in designing novel agents to modulate signaling pathways to prevent HBV replication or carcinogenesis.

Anti-hepatitis B virus activity and hepatoprotective effect of des(rhamnosyl) verbascoside from Lindernia ruellioides in vitro

Although clinically approved hepatitis B virus (HBV) polymerase inhibitors (lamivudine-3TC, entecavir, etc.) serve as effective therapeutics, the virus can easily generate resistance to them. Therefore, the treatment of HBV infection remains a public health problem. Numerous studies have shown that natural products have prospective anti-HBV activity. The purpose of this study was to isolate and extract des(rhamnosyl) verbascoside from Lindernia ruellioides (Colsm.) Pennell and explore its anti-HBV and hepatoprotective effects. Anti-HBV activity was evaluated in HepG2.2.15 cells, a human hepatocellular carcinoma cell line with HBV-stable infection, and its protective effect was evaluated in HL-7702 cells, a normal human liver cell line. HepG2.2.15 cells maintained normal growth morphology within the selected concentration range of des(rhamnosyl) verbascoside. It also inhibited the expression of HBV antigens and HBV DNA in a dose- and time-dependent manner in vitro. Further, western blot experiments showed that it could downregulate HBV X protein (HBx) expression in a dose-dependent manner. In the H₂ O₂ -induced hepatocyte injury model, the cell-survival rate of the HL-7702 cells with the highest drug dose reached 85.25%, which was significantly improved compared with that of the model group. Most of the cells returned to normal morphology, showing polygonal or fusiform structures. Thus, it may be stated that des(rhamnosyl) verbascoside exhibits anti-HBV activity and hepatoprotective effects in vitro and may exert an anti-HBV effect via antigen inhibition, HBV DNA secretion, and HBx protein expression.

The USP18 cysteine protease promotes HBV production independent of its protease activity

Background

Hepatitis B virus (HBV) infection remains as one of the major public health problems in the world. Type I interferon (IFN) plays an essential role in antiviral defense by induced expression of a few hundred interferon stimulated genes (ISGs), including ubiquitin-specific protease 18 (USP18). The expression level of USP18 was elevated in the pretreatment liver tissues of chronic hepatitis B(CHB) patients who did not respond to IFN treatment. Thus, this study was designed to investigate the effects of USP18 on HBV replication/production.

Methods

The levels of wild type USP18(WT-USP18) and USP18 catalytically inactive form C64S were up-regulated by plasmids transfection in HepAD38 cells, respectively. Real-time PCR and ELISA were used to quantify HBV replication. Type I IFN signaling pathway was monitored at three levels: p-STAT1 (western Blot), interferon stimulated response element (ISRE) activity (dual luciferase assay) and ISGs expression (real time PCR).

Results

Our data demonstrated that overexpression of either WT-USP18 or USP18-C64S inactive mutant increased the intracellular viral pgRNA, total DNA, cccDNA, as well as HBV DNA levels in the culture supernatant, while silencing USP18 led to opposite effect on HBV production. In addition, upregulated WT-USP18 or USP18-C64S suppressed ISRE activity and the expression levels of p-STAT1 and ISGs.

Conclusion

USP18 promoted HBV replication via inhibiting type I IFN signaling pathway, which was independent of its protease activity.

High yield expression, characterization, and biological activity of IFNα2-Tα1 fusion protein

The use of interferon α-2 in combination with thymosin α-1 shows higher anti-cancer effect in comparison when both are used individually because of their synergistic effects. In this study we produced an important human interferon α-2-thymosin α-1 (IFNα2-Tα1) fusion protein with probable pharmaceutical properties coupled to its high-level expression, characterization, and study of its biological activity. The IFNα2-Tα1 fusion gene was constructed by over-lap extension PCR and expressed in Escherichia coli expression system. The expression of IFNα2-Tα1 fusion protein was optimized to higher level and its maximum expression was obtained in modified terrific broth medium when lactose was used as inducer. The fusion protein was refolded into its native biologically active form with maximum yield of 83.14% followed by purification with ∼98% purity and 69% final yield. A band of purified IFNα2-Tα1 fusion protein equal to ∼23 kDa was observed on 12 % SDS-PAGE gel. The integrity of IFNα2-Tα1 fusion protein was confirmed by western blot analysis and secondary structure was assessed by CD spectroscopy. When IFNα2-Tα1 fusion protein was subjected to its biological activity analysis it was observed that it exhibits both IFNα2 & Tα1 activities as well as significantly higher anticancer activity as compared to IFNα-2 alone.

Comprehensive Proteomics Identification of IFN-λ3-regulated Antiviral Proteins in HBV-transfected Cells

Interferon lambda (IFN-λ) is a relatively unexplored, yet promising antiviral agent. IFN-λ has recently been tested in clinical trials of chronic hepatitis B virus infection (CHB), with the advantage that side effects may be limited compared with IFN-α, as IFN-λ receptors are found only in epithelial cells. To date, IFN-λ's downstream signaling pathway remains largely unelucidated, particularly via proteomics methods. Here, we report that IFN-λ3 inhibits HBV replication in HepG2.2.15 cells, reducing levels of both HBV transcripts and intracellular HBV DNA. Quantitative proteomic analysis of HBV-transfected cells was performed following 24-hour IFN-λ3 treatment, with parallel IFN-α2a and PBS treatments for comparison using a dimethyl labeling method. The depth of the study allowed us to map the induction of antiviral proteins to multiple points of the viral life cycle, as well as facilitating the identification of antiviral proteins not previously known to be elicited upon HBV infection (e.g. IFITM3, XRN2, and NT5C3A). This study also shows up-regulation of many effectors involved in antigen processing/presentation indicating that this cytokine exerted immunomodulatory effects through several essential molecules for these processes. Interestingly, the 2 subunits of the immunoproteasome cap (PSME1 and PSME2) were up-regulated whereas cap components of the constitutive proteasome were down-regulated upon both IFN treatments, suggesting coordinated modulation toward the antigen processing/presentation mode. Furthermore, in addition to confirming canonical activation of interferon-stimulated gene (ISG) transcription through the JAK-STAT pathway, we reveal that IFN-λ3 restored levels of RIG-I and RIG-G, proteins known to be suppressed by HBV. Enrichment analysis demonstrated that several biological processes including RNA metabolism, translation, and ER-targeting were differentially regulated upon treatment with IFN-λ3 versus IFN-α2a. Our proteomic data suggests that IFN-λ3 regulates an array of cellular processes to control HBV replication.

Interleukin-35 Level Is Elevated in Patients with Chronic Hepatitis B Virus Infection

Backgrounds: As one of the major public health problems, the hepatitis B virus (HBV) infection would activate the immune system. The outcome of HBV infection was affect significantly by the interactions between HBV and host immune response. Interleukins play important role in anti-viral immunity. Here we investigated the role of interleukin-35 (IL-35) in chronic HBV infection patients. Methods/Results: Serum IL-35 in 72 chronic hepatitis B virus infection patients and 41 healthy control subjects were analyzed by ELISA assay. The mRNA level of IL-35 in PBMCs was determined by RT-qPCR. In this study, we found that both protein and mRNA levels of IL-35 were significantly decreased in chronic HBV patients compared to the healthy controls. Furthermore, the statistical analysis found that serum IL-35 was significantly associated with HBV DNA (P =0.0158), ALT (P =0.0003), AST (P =0.0216), TB (P =0.0270) and AFP (P =0.0369). Importantly, correlation analysis also found that serum IL-35 level was negatively correlated with HBV DNA copies, ALT, AST, TB and AFP. Meanwhile, IL-35 treatment inhibited the level of HBV DNA, HBsAg and HBeAg in HepAD38 cells. Conclusion: Our study identified that IL-35 may be a novel marker associated with HBV infection and hepatocytes injury. These data suggested the potential use of IL-35 in the HBV treatment.

A functional variant in the OAS1 gene is associated with Sjögren's syndrome complicated with HBV infection

Hepatitis B virus (HBV) has been suspected to contribute to several autoimmune diseases, including Sjögren's syndrome (SS), although the exact mechanism is unknown. The 2'-5' oligoadenylate synthetase (OAS1) is one of the most important components of the immune system and has significant antiviral functions. We studied a polymorphism rs10774671 of OAS1 gene in Han Chinese descent. The minor allele G was significantly associated with a decreased risk for SS, anti-SSA-positive SS, and anti-SSA-positive SS complicated with HBV infection, which have not been seen in anti-SSA-negative SS and HBcAb-negative SS patients. Gene expression analysis showed that the risk-conferring A allele was correlated with lower expression of p46 and increased expression of p42, p48, and p44. A functional study of enzymatic activities revealed that the p42, p44, and p48 isoforms display a reduced capacity to inhibit HBV replication in HepG2 cells compared to the normal p46 isoform. Our data demonstrated that the functional variant, rs10774671, is associated with HBV infection and anti-SSA antibody-positive SS. The SAS variant switches the primary p46 isoform to three alternatives with decreased capacities to inhibit HBV replication. These data indicated that individuals harboring the risk allele might be susceptible to hepatitis B infection and SS development.

Production of bioactive liver-targeting interferon Mu-IFN-CSP by soluble prokaryotic expression

A novel liver-targeting interferon (IFN-CSP) was successfully over-expressed in our previous work. The in vitro and in vivo investigation revealed that IFN-CSP has significant anti-hepatitis B virus (HBV) effect and liver-targeting capacity. However, due to the IFN-CSP tends to form inclusion bodies in recombinant Escherichia coli (E. coli), efficient production of the soluble liver-targeting interferon is a challenge. In view of biomedical application, novel strategies for efficiently expressing liver-targeting interferon and overcoming its poor solubility are necessary and important. In the present study, a modified mu-IFN-CSP was designed base on the amino acid mutant of the native IFN-CSP. Meanwhile, the coding sequence of mu-IFN-CSP was optimized for E. coli preferred codon and the induction conditions for expression were optimized by an orthogonal test. After amino acid mutant, codon optimization and induction conditions optimization, the solubility of Mu-IFN-CSP in E. coli was up to 98.4%. The structural comparison and molecular dynamic simulation showed that the Mu-IFN-CSP formed three structure changes and were more stable than the native IFN-CSP. Tissue sections binding assays revealed that Mu-IFN-CSP was also able to specific binding to liver. In vitro anti-HBV activity assays showed that the soluble Mu-IFN-CSP has improved anti-HBV effect in HepG2.2.15 cells compared to the native IFN-CSP. The present study reports for the first time that liver-targeting interferon Mu-IFN-CSP can be expressed as soluble form, and also contributes to further support its application as liver-targeting anti-HBV medicine.

Combination antiretroviral therapy (cART) restores HIV-1 infection-mediated impairment of JAK-STAT signaling pathway

JAK-STAT signaling pathway has a crucial role in host innate immunity against viral infections, including HIV-1. We therefore examined the impact of HIV-1 infection and combination antiretroviral therapy (cART) on JAK-STAT signaling pathway. Compared to age-matched healthy donors (n = 18), HIV-1-infected subjects (n = 18) prior to cART had significantly lower expression of toll-like receptors (TLR-1/4/6/7/8/9), the IFN regulatory factors (IRF-3/7/9), and the antiviral factors (OAS-1, MxA, A3G, PKR, and Tetherin). Three months’ cART partially restores the impaired functions of JAK-STAT-mediated antiviral immunity. We also found most factors had significantly positive correlations (p < 0.05) between each two factors in JAK-STAT pathway in healthy donors (98.25%, 168/171), but such significant positive associations were only found in small part of HIV-1-infected subjects (43.86%, 75/171), and stably increased during the cART (57.31%, 98/171 after 6 months’ cART). With regard to the restoration of some HIV-1 restriction factors, HIV-1-infected subjects who had CD4+ T cell counts > 350//μl responded better to cART than those with the counts < 350/μl. These findings indicate that the impairment of JAK-STAT pathway may play a role in the immunopathogenesis of HIV-1 disease.

Interferon-Stimulated Gene 15 Conjugation Stimulates Hepatitis B Virus Production Independent of Type I Interferon Signaling Pathway In Vitro

Hepatitis B virus (HBV) is an important account of infectious hepatitis and interferon (IFN) remains one of the best treatment options. Activation of type I IFN signaling pathway leads to expressions of IFN-stimulated genes (ISGs) which play important roles in antiviral and immunomodulatory responses to HBV or hepatitis C virus (HCV) infection. Our previous studies indicated that ISG15 and its conjugation (ISGylation) were exploited by HCV to benefit its replication and persistent infection. This study was designed to assess the role of ISG15 and ISGylation in HBV infection in vitro. The levels of ISG15 and ISGylation were upregulated by ISG15 plasmid transfection into HepG2.2.15 cells. Decreased ISGylation was achieved by siRNA targeting UBE1L, the only E1 activating enzyme for ISGylation. Overexpression of ISG15 and subsequent ISGylation significantly increased the levels of HBV DNA in the culture supernatants although the intracellular viral replication remained unaffected. Silencing UBE1L, with decreased ISGylation achieved, abrogated this ISGylation-mediated promoting effect. Our data indicated that overexpression of ISG15 stimulated HBV production in an ISGylation-dependent manner. Identification of ISG15-conjugated proteins (either HBV viral or host proteins) may reveal promising candidates for further antiviral drug development.

Role of Baicalin in Anti-Influenza Virus A as a Potent Inducer of IFN-Gamma

Baicalin (BA) is a flavonoid compound purified from Scutellaria baicalensis Georgi and has been shown to possess a potent inhibitory activity against viruses. However, the role of BA in anti-influenza virus has not been extensively studied, and the immunological mechanism of BA in antiviral activity remains unknown. Here, we observed that BA could protect mice from infection by influenza virus A/PR/8/34 (H₁N₁), associated with increasing IFN-γ production, but presented no effects in IFN-γ or IFN-γ receptor deficient mice. Further study indicated that BA could inhibit A/PR/8/34 replication through IFN-γ in human PBMC. Moreover, BA can directly induce IFN-γ production in human CD4⁺ and CD8⁺ T cells and NK cells, and activate JAK/STAT-1 signaling pathway. Collectively, BA exhibited anti-influenza virus A (H₁N₁) activity in vitro and in vivo as a potent inducer of IFN-γ in major IFN-γ producing cells.

High-level expression of a novel liver-targeting fusion interferon with preferred Escherichia coli codon preference and its anti-hepatitis B virus activity in vivo

Background

In our previous study, a novel liver-targeting fusion interferon (IFN-CSP) combining IFN α2b with plasmodium region I peptide was successfully constructed. IFN-CSP has significant inhibition effects on HBV-DNA replication in HepG2.2.15 cells. The aim of the present investigation was focused on how to produce high levels of recombinant IFN-CSP and its in vivo anti-hepatitis B virus (HBV) activity.

Methods

A modified DNA fragment encoding IFN-CSP was synthesized according to Escherichia coli (E. coli) preferred codon usage and transformed into E. coli BL21 (DE3) for protein expression. The induction conditions were systematically examined by combining one-factor experiments with an orthogonal test (L(9)(3)(4)). The antigenicity of the purified protein was characterized by western blot analysis. The in vivo tissue distribution were assayed and compared with native IFN α2b. HBV-transgenic mice were used as in vivo model to evaluate the anti-HBV effect of the recombinant IFN-CSP.

Results

The results showed that the E. coli expression system was very efficient to produce target protein.

Conclusion

Our current research demonstrates for the first time that IFN-CSP gene can be expressed at high levels in E. coli through codon and expression conditions optimization. The purified recombinant IFN-CSP showed liver-targeting potentiality and anti-HBV activity in vivo. The present study further supported the application of IFN-CSP in liver-targeting anti-HBV medicines.