Search Results (294)

The innate immune response is an important defense against invading pathogens. Stimulator of interferon gene (STING) plays an important role in the cyclic GMP-AMP synthase (cGAS)-mediated activation of type I IFN responses. However, some viruses have evolved the ability to inhibit the function of STING and evade the host antiviral defenses. Understanding both the mechanism of action and the viruses targets of STING effector is important because of their importance to evade the host antiviral defenses. In this study, the STING (IpSTING) of Ictalurus punctatus was first identified and characterized. Subsequently, the yeast two-hybrid system (Y2HS) was used to screen for proteins from channel catfish virus (CCV, Ictalurid herpesvirus 1) that interact with IpSTING. The ORFs of the CCV were cloned into the pGBKT7 vector and expressed in the AH109 yeast strain. The bait protein expression was validated by autoactivation, and toxicity investigation compared with control (AH109 yeast strain transformed with empty pGBKT7 and pGADT7 vector). Two positive candidate proteins, ORF41 and ORF65, were identified through Y2HS screening as interacting with IpSTING. Their interactions were further validated using co-immunoprecipitation (Co-IP). This represented the first identification of interactions between IpSTING and the CCV proteins ORF41 and ORF65. The data advanced our understanding of the functions of ORF41 and ORF65 and suggested that they might contribute to the evasion of host antiviral defenses. However, the interaction mechanism between IpSTING, and CCV proteins ORF41 and ORF65 still needs to be further explored. Full article

Interferon (IFN) signaling plays vital roles in host defense against viral infection. However, a variety of observations have been reported in the literature regarding the roles of IFN signaling in COVID-19. Thus, it would be important to reach a clearer picture regarding the activation or suppression of IFN signaling in COVID-19. In this work, regulation of marker genes for IFN signaling was examined in natural infection, viral challenge, and vaccination based on 13 public transcriptome datasets. Three subsets of interferon-stimulated genes (ISGs) were selected for detailed examination, including one set of marker genes for type I IFN signaling (ISGa) and two sets of marker genes for type II IFN signaling (IFN-γ signaling, GBPs for the GBP gene cluster, and HLAd for the HLA-D gene cluster). In natural infection, activation of ISGa and GBPs was accompanied by the suppression of HLAd in hospitalized patients. Suppression of GBPs was also observed in certain critical conditions. The scale of regulation was much greater for ISGa than that of GBPs and HLAd. In addition, the suppression of HLAd was correlated with disease severity, and it took much longer for HLAd to return to the level of healthy controls than that for ISGa and GBPs. Upon viral challenge, the activation of ISGa and GBPs was similar to that of natural infection, while the suppression of HLAd was not observed. Moreover, GBPs’ return to the pre-infection level was at a faster pace than that of ISGa. Upon COVID-19 vaccination, activation was observed for all of these three gene sets, and the scale of activation was comparable for ISGa and GBPs. Notably, it took a much shorter time for GBPs and ISGa to return to the level of healthy controls than that in COVID-19 infection. In addition, the baseline values and transient activation of these gene sets were also associated with subsequent vaccination response. The intricate balance of IFN signaling was demonstrated in mild breakthrough infection, where attenuated response was observed in people with prior vaccination compared to that in vaccine-naïve subjects. Overall, distinctive temporal profiles of IFN signaling were observed in natural infection, viral challenge, and vaccination. The features observed in this work may provide novel insights into the disease management and vaccine development. Full article

Myxoma virus (MYXV), a rabbit-specific poxvirus and non-pathogenic in humans and mice, is an excellent candidate oncolytic virus for cancer therapy. MYXV also has immunotherapeutic benefits. In ovarian cancer (OC), immunosuppressive tumor-associated macrophages (TAMs) are key to inhibiting antitumor immunity while hindering therapeutic benefit by chemotherapy and dendritic cell (DC) vaccine. Because MYXV favors binding/entry of macrophages/monocytes, we examined the therapeutic potential of MYXV against TAMs. We found previously that a replication-defective MYXV with targeted deletion of an essential gene, M062R, designated ΔM062R MYXV, activated both the host DNA sensing pathway and the SAMD9 pathway. Treatment with ΔM062R confers therapeutic benefit comparable to that of wild-type replicating MYXV in preclinical models. Here we found that ΔM062R MYXV, when integrated with cisplatin and DC immunotherapy, further improved treatment benefit, likely through promoting tumor antigen-specific T cell function. Moreover, we also tested ΔM062R MYXV in targeting human immunosuppressive TAMs from OC patient ascites in a co-culture system. We found that ΔM062R treatment subverted the immunosuppressive properties of TAMs and elevated the avidity of cytokine production in tumor antigen-specific CD4⁺ T cells. Overall, ΔM062R presents a promising immunotherapeutic platform as a beneficial adjuvant to chemotherapy and DC vaccine. Full article

The B-cell adapter for PI3K (BCAP) is a protein that connects membrane receptor signaling to the PI3K pathway. In fibroblasts or dendritic cells, priming the cGAS nucleic-acid-sensing pathway increases BCAP expression and enhances type I interferon (IFN-I) production upon lipopolysaccharide (LPS) stimulation. These findings corroborate the idea that BCAP may bias cytokine production toward IFN during inflammation, indicating its potential involvement in IFN-driven diseases like systemic lupus erythematosus (SLE). We investigate the role of BCAP in regulating the inflammatory response in SLE and its relationship with IFN-mediated inflammation. BCAP gene expression and IFN signature were analyzed in 36 subjects with SLE and 20 healthy controls. Two cellular models were used to assess BCAP’s role in LPS response and IFN signaling after cGAS stimulation. We found a correlation between BCAP and interferon-stimulated gene (ISG) expression in SLE. In a cellular model, tofacitinib and anifrolumab, acting as IFN signaling “inhibitors”, blocked BCAP overexpression triggered by cGAS, confirming BCAP as an ISG. Additional studies in BCAP^−/− cells revealed that, in the absence of BCAP, these cells exhibited diminished IFN production upon LPS stimulation following prior exposure to cGAMP. Overall, BCAP is an ISG that acts as a positive regulator of Toll-like receptor 4-mediated IFN production. We speculate that its increased expression in SLE may contribute to a positive feedback loop, enhancing IFN production during bacterial infections. Full article

Early embryonic loss is a major cause of reproductive inefficiency in cattle, primarily due to premature luteolysis. Interferon tau (IFN-τ), secreted by the trophoblast, plays a critical role in maternal recognition of pregnancy by maintaining corpus luteum function. However, its practical application has been limited by its rapid degradation and short half-life in vivo. Here, we developed a novel formulation of recombinant bovine IFN-τ, combining chitosan-based microencapsulation with starch–chitosan hydrogel delivery, enabling sustained intrauterine release. This dual-delivery strategy offers a significant improvement over conventional IFN-τ administration methods that rely on repeated intrauterine infusions of soluble protein. The rbIFN-τ was expressed in Pichia pastoris, purified to 90.1% homogeneity, and structurally validated via homology modeling and molecular docking, confirming its interaction with type I interferon receptors. The encapsulated formulation retained antiviral activity, stimulated transcription of interferon-stimulated genes (PKR, OAS1, OAS2), and showed sustained release in vitro for up to 26 days. In vivo evaluation demonstrated safety and biological efficacy, with treated cattle showing inhibited luteolysis, sustained serum progesterone levels, and preserved corpus luteum integrity. This formulation represents a promising biotechnological approach to improve reproductive efficiency through a long-acting, species-specific IFN-τ delivery system. Full article

Background: Vaccines represent one of the most affordable and efficient tools for controlling infectious diseases; however, the development of efficacious vaccines against complex pathogens remains a major challenge. Adjuvants play a relevant role in enhancing vaccine-induced immune responses. One such molecule is interferon-stimulated gene 15 (ISG15), a key modulator of antiviral immunity that acts both through ISGylation-dependent mechanisms and as a cytokine-like molecule. Methods: In this study, we assessed the immunostimulatory potential of ISG15 as an adjuvant in Modified Vaccinia virus Ankara (MVA)-based vaccine candidates targeting Zika virus (ZIKV) and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Early innate responses and immune cell infiltration were analyzed in immunized mice by flow cytometry and cytokine profiling. To elucidate the underlying mechanism of action of ISG15, in vitro co-infection studies were performed in macrophages. Finally, we evaluated the magnitude and functional quality of the elicited antigen-specific cellular immune responses in vivo. Results: Analysis of early innate responses revealed both platform- and variant-specific effects. ISG15AA preferentially promoted natural killer (NK) cell recruitment at the injection site, whereas ISG15GG enhanced myeloid cell infiltration in draining lymph nodes (DLNs), particularly when delivered via MVA. Moreover, in vitro co-infection of macrophages with MVA-based vaccine vectors and the ISG15AA mutant led to a marked increase in proinflammatory cytokine production, highlighting a dominant role for the extracellular, ISGylation-independent functions of ISG15 in shaping vaccine-induced immunity. Notably, co-infection of ISG15 with MVA-ZIKV and MVA-SARS-CoV-2 vaccine candidates enhanced the magnitude of antigen-specific immune responses in both vaccine models. Conclusions: ISG15, particularly in its ISGylation-deficient form, acts as a promising immunomodulatory adjuvant for viral vaccines, enhancing both innate and adaptive immune responses. Consistent with previous findings in the context of Human Immunodeficiency virus type 1 (HIV-1) vaccines, this study further supports the potential of ISG15 as an effective adjuvant for vaccines targeting viral infections such as ZIKV and SARS-CoV-2. Full article

Background: The STING (Stimulator of Interferon Genes) pathway plays a vital role in the body’s innate immune defense system, primarily involved in DNA sensing and type I interferon production. While STING is well-established in various immune cells, its role in natural killer (NK) cells, particularly within the context of liver fibrosis, remains inadequately explored. Aim: The current study investigates the relationship between STING expression, NK cell activity, and insulin receptor (IR) signaling in patients with metabolic dysfunction-associated steatohepatitis (MASH). Methods: Peripheral NK cells were isolated from healthy controls and MASH patients with varying stages of liver fibrosis (early: F1/F2; advanced: F3/F4). The expressions of STING, IR, NK cell activation markers (CD107a, NKp46), and NK cell inhibitory markers (LAIR-1, Siglec-7) were assessed using flow cytometry. NK cell cytotoxicity against primary hepatic stellate cells (pHSCs) was evaluated through apoptosis assays. STING agonists (2′3′-cGAMP and DMXAA) were used to stimulate NK cells, and their effects on STING expression, NK cell activation, and cytotoxicity were measured. Additionally, the impact of insulin signaling on STING expression and NK cell function was examined. Results: Our results demonstrate that STING expression in NK cells correlates with disease severity in liver fibrosis. NK cells from MASH patients with advanced fibrosis (F3/F4) showed inhibited STING protein levels that were statistically comparable to healthy NK cells and accompanied by impaired cytotoxicity and decreased IFN-γ production. In contrast, NK cells from early fibrosis (F1/F2) exhibited higher STING expression and better functional activity. STING agonist treatment (2′3′-cGAMP) restored STING expression and enhanced NK cell activity across all fibrosis stages. Furthermore, insulin treatment and combined insulin and 2′3′-cGAMP treatment synergistically upregulated both IR and STING expressions, leading to improved NK cell function and increased cytotoxicity, particularly in advanced fibrosis. Conclusion: Our results highlight the potential of targeting STING and insulin signaling pathways as a therapeutic approach in restoring NK cell function and enhance immune surveillance in liver fibrosis. Full article

The DNA-damage response (DDR) network and the immune system are significant mechanisms linked to the normal functioning of living organisms. Extensive observations suggest that agents that damage the DNA can boost immunity in various ways, some of which may be useful for immunotherapeutic applications. Indeed, the immune system can be activated by the DDR network through a number of different mechanisms, such as via (a) an increase in the tumor neoantigen burden, (b) the induction of the stimulator of interferon genes pathway, (c) the triggering of immunogenic cell death, (d) an increase in antigen presentation as a result of the augmented expression of the major histocompatibility complex type I molecule, (e) modification of the cytokine milieu in the tumor microenvironment, and (f) altered expression of the programmed cell death ligand-1. Together, the DDR network may improve the effect of immunostimulatory anticancer agents and provide a basis for devising more efficient treatment strategies, such as combinatorial therapies of DDR targeting drugs and immunomodulators. Here, the molecular mechanisms underlying the immune system’s activation by DDR are summarized, along with some of their possible uses in cancer treatment. Full article

The immediate-early protein IE180 of pseudorabies virus (PRV) is a multifunctional regulator of viral and host gene expression. However, its role in modulating antiviral immune responses remains poorly understood. Here, we demonstrate that IE180 overexpression significantly inhibits PRV and H1N1 influenza virus replication in Hep2 and A549 cells, respectively. Mechanistically, IE180 activates the type I interferon (IFN-I) pathway by enhancing IFN-β promoter activity and IFN transcription, leading to upregulated expression of interferon-stimulated genes (ISGs). Notably, IE180 failed to suppress PRV or H1N1 replication in Vero cells, which lack functional IFN-I signaling, confirming the dependence of its antiviral function on the IFN-I pathway. Domain mapping revealed that the ICP4-Like2 domain of IE180 is critical for IFN-β activation and antiviral activity. These findings establish IE180 as a novel viral immunomodulator that activates host innate immunity to restrict viral replication, providing insights into PRV-host interactions and potential therapeutic strategies. Full article

Interferon (IFN)-induced proteins with tetratricopeptide repeats (IFITs) are key interferon-stimulated genes (ISGs), and in humans include IFIT1, IFIT2, IFIT3 and IFIT5. These proteins are primarily known for their role in the innate immune response to pathogens. However, growing evidence suggests that IFITs participate in a range of other cellular processes, including cancer development and progression. Notably, IFITs may behave in either a pro-oncogenic or tumor suppressive fashion depending on cancer types and emphasizing their potential dual function in tumorigenesis. Importantly, IFITs have shown potential to be utilized as clinical biomarkers in oncology. Their aberrant expression has been correlated with survival and other clinical outcomes, including resistance to radiotherapy, chemotherapy, targeted treatments and immunotherapy in various cancers. Additionally, they have also been reported to be a part of various clinical predictive models in cancers. This review provides an overview of the current understanding of IFIT proteins’ involvement in cancers, with an emphasis on their emerging roles as clinically relevant biomarkers. Full article

The pandemic of Coronavirus Disease 2019 has triggered a worldwide public health emergency. Its pathogen, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has developed multiple strategies for effectively evading the host immune defenses, including inhibition of interferon (IFN) signaling. Several viral proteins of SARS-CoV-2 are believed to interfere with IFN signaling. In this study, we found that the SARS-CoV-2 accessory protein ORF7a considerably impaired IFN-activated Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling via suppression of the nuclear translocation of IFN-stimulated gene factor 3 (ISGF3) and the activation of STAT2. ORF7a dampened STAT2 activation without altering the expression and phosphorylation of Janus kinases (JAKs). A co-immunoprecipitation (co-IP) assay was performed to gather ORF7a protein, but it failed to precipitate STAT2. Interestingly, mass spectrometry and immunoblotting analyses of the ORF7a co-IP product revealed that ORF7a interacted with an RNA-binding protein, heterogeneous nuclear ribonucleoprotein A2B1 (HNRNPA2B1), and HNRNPA2B1 was related to the inhibitory effect of ORF7a on STAT2 phosphorylation. Moreover, examination of ORF7a deletion constructs revealed that the C-terminal region of ORF7a (amino acids 96 to 122) is crucial for suppressing IFN-induced JAK/STAT signaling activation. In conclusion, we discovered that SARS-CoV-2 ORF7a antagonizes type I IFN-activated JAK/STAT signaling by interacting with HNRNPA2B1, and the C-terminal region of ORF7a is responsible for its inhibitory effect. Full article

Type I interferons (IFN-Is) play a dual role in the immune response to HIV-1, providing early antiviral defense while driving immune dysfunction in the chronic phase. During acute infection, robust IFN signaling is critical in controlling viral replication, activating innate immunity, and limiting reservoir establishment. However, sustained IFN-I activation during chronic infection fuels systemic inflammation, immune exhaustion, and fibrosis, particularly in lymphoid tissues such as gut-associated lymphoid tissue (GALT). Prolonged IFN-I exposure upregulates inhibitory receptors on T cells, impairs metabolic fitness, and fosters an immunosuppressive cytokine milieu that weakens overall immune responses. In contrast to natural SIV (Simian immunodeficiency virus) hosts, IFN-I responses are tightly regulated to prevent chronic immune activation and tissue damage. However, humans and non-natural hosts experience persistent Interferon Stimulated Gene (ISG) expression and IFN-I driven inflammation. Emerging therapeutic strategies seek to harness the antiviral benefits of IFN-I while mitigating its pathogenic effects. Approaches such as the IFNAR blockade, autophagy induction, JAK-STAT inhibition, and combined immune inhibitory blockade therapy show promise in restoring immune balance and enhancing T cell function. This review examines the mechanisms of IFN-I dysregulation in chronic HIV-1 infection and highlights novel interventions aimed at finetuning IFN-I signaling for therapeutic benefit. Full article

Human type I interferons are crucial regulators of immune responses, essential for controlling infections and activating immune cells. Among them, Interferon Beta (IFNB1) plays a key role in inflammation, and its dysregulation is linked to various diseases, driving efforts to understand the molecular events governing its expression. Here, we identified Mitogen-Activated Protein Kinase 15 (MAPK15) as a novel regulator of IFNB1. Using luciferase reporter assays, gene expression analysis and Enzyme-Linked Immunosorbent Assay (ELISA), we found that MAPK15 downregulation enhanced IFNB1 and Interferon-Stimulated Genes expression and increased IFNB1 secretion. To unveil the underlying mechanisms, we investigated the transcription factors acting on the IFNB1 promoter, revealing that MAPK15 downregulation induced JUN activation. Importantly, pharmacological inhibition of c-Jun N-terminal Kinases (JNKs) supported a key role for this enzyme in JUN activation and consequent IFNB1 expression. Ultimately, by using the antioxidant N-acetylcysteine ethyl ester (NACET), we demonstrated that oxidative stress, induced by MAPK15 downregulation, was responsible for JUN activation and IFNB1 expression. Overall, our findings unveil a novel mechanism by which MAPK15 modulates IFNB1 expression, positioning this kinase as a pivotal regulator of this gene. This insight opens promising avenues for therapeutic intervention, as targeting MAPK15 activity could offer a strategy to rebalance cytokine expression in chronic inflammatory diseases characterized by immune dysregulation. Full article

Mesenchymal stromal cells (MSCs) represent a promising therapeutic approach in viral infection management. However, their interaction with viruses remains poorly understood. MSCs can support antiviral immune responses and act as viral reservoirs, potentially compromising their therapeutic potential. Innate immune system recognition of viral pathogens involves pattern recognition receptors (PRRs), including RIG-I-like receptors (RLRs), which activate mitochondrial antiviral signaling protein (MAVS). MAVS triggers antiviral pathways like IRF3 and NF-κB, leading to interferon (IFN) production and pro-inflammatory responses. This study explores the antiviral response in umbilical cord-derived MSCs (UC-MSCs) through targeted stimulation with influenza A virus-derived 5′triphosphate-RNA (3p-hpRNA), a RIG-I agonist. By investigating MAVS activation, we provide mechanistic insights into the immune response at the molecular level. Our findings reveal that 3p-hpRNA stimulation triggers immune activation of the IRF3 and NF-κB pathways through MAVS. Subsequently, this leads to the induction of type I and III IFNs, IFN-stimulated genes (ISGs), and pro-inflammatory cytokines. Critically, this immune activation occurs without compromising mitochondrial integrity. UC-MSCs retain their capacity for mitochondrial transfer to recipient cells. These results highlight the adaptability of UC-MSCs, offering a nuanced understanding of immune responses balancing activation with metabolic integrity. Finally, our research provides mechanistic evidence for MSC-based interventions against viral infections. Full article

The Janus kinase 2 (JAK2) protein fulfills an important role in hematopoiesis via the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway, as it provides the genetic driver of BCR::ABL1-negative myeloproliferative neoplasms (MPNs), which are clinically manifested as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The most common cause of MPNs is the mutation of JAK2 V617F in the JAK2 gene, which results in increased cell proliferation. However, both the pathogenesis and treatment regimen of BCR::ABL1-negative MPNs remain poorly understood. The aim of the present study was to establish K562 cell lines with a point mutation in exon 14 (JAK2p.V617F) using CRISPR/Cas9 technology. The modified JAK2 V617F cell lines were examined for the gene mutation using droplet digital PCR (DDPCR), and the presence of the mutation was confirmed by DNA sequencing. Modified cells were characterized by measuring JAK2 gene expression and the extent of cell proliferation. Interferon α2a (IFN-α2a) and arsenic trioxide were also administered to the cells to explore their potential effects. The JAK2 V617F-mutated cells were found to exhibit a higher level of JAK2 gene expression compared with the wild type. Interestingly, a significant increase in the proliferation rate was observed with the modified cells compared with the wild type cells (p < 0.001), as assessed from the JAK2 gene expression levels. Furthermore, the treatments with IFN-α2a and arsenic trioxide led to the preferential suppression of the cell proliferation rate of the K562 expressing mutant JAK2 cells compared with the wild type cells, and this suppression occurred in a dose-dependent manner(p < 0.01). Moreover, the modified cells were able to differentiate into megakaryocyte-like cells following stimulation with phorbol 12 myristate 13 acetate (PMA). Taken together, the results of the present study have shown that the CRISPR/Cas9-modified JAK2 V617F model may be used as a disease model in the search of novel therapies for MPNs. Full article