A virus-induced conformational switch of STAT1-STAT2 dimers boosts antiviral defenses

Alizarin attenuates oxidative stress-induced mitochondrial damage in vascular dementia rats by promoting TRPM2 ubiquitination and proteasomal degradation via Smurf2

BACKGROUND

Alizarin (AZ) is a natural anthraquinone with anti-inflammatory and moderate antioxidant properties.

PURPOSE

In this study, we characterized the role of AZ in a rat model of vascular dementia (VaD) and explored its underlying mechanisms.

METHODS

VaD was induced by bilateral common carotid artery occlusion.

RESULTS

We found that AZ attenuated oxidative stress and improved mitochondrial structure and function in VaD rats, which led to the improvement of their learning and memory function. Mechanistically, AZ reduced transient receptor potential melastatin 2 (TRPM2) expression and activation of the Janus-kinase and signal transducer activator of transcription (JAK-STAT) pathway in VaD rats. In particular, the reduction in the expression of TRPM2 channels was the key to the attenuation of the oxidative stress-induced mitochondrial damage, which may be achieved by increasing the expression of the E3 ubiquitin ligase, Smad-ubiquitination regulatory factor 2 (Smurf2); thereby increasing the ubiquitination and degradation levels of TRPM2.

CONCLUSION

Our results suggest that AZ is an effective candidate drug for ameliorating VaD and provide new insights into the current clinical treatment of VaD.

Transcriptional control of interferon-stimulated genes

Interferon-induced genes are among the best-studied groups of coregulated genes. Nevertheless, intense research into their regulation, supported by new technologies, is continuing to provide insights into their many layers of transcriptional regulation and to reveal how cellular transcriptomes change with pathogen-induced innate and adaptive immunity. This article gives an overview of recent findings on interferon-induced gene regulation, paying attention to contributions beyond the canonical JAK-STAT pathways.

Neuromodulatory co-expression in cardiac vagal motor neurons of the dorsal motor nucleus of the vagus

Vagal innervation is well known to be crucial to the maintenance of cardiac health, and to protect and recover the heart from injury. Only recently has this role been shown to depend on the activity of the underappreciated dorsal motor nucleus of the vagus (DMV). By combining neural tracing, transcriptomics, and anatomical mapping in male and female Sprague-Dawley rats, we characterize cardiac-specific neuronal phenotypes in the DMV. We find that the DMV cardiac-projecting neurons differentially express pituitary adenylate cyclase-activating polypeptide (PACAP), cocaine- and amphetamine-regulated transcript (CART), and synucleins, as well as evidence that they participate in neuromodulatory co-expression involving catecholamines. The significance of these findings is enhanced by previous knowledge of the role of PACAP at the heart and of the other neuromodulators in peripheral vagal targets.

African swine fever virus pB475L evades host antiviral innate immunity via targeting STAT2 to inhibit IFN-I signaling

African swine fever virus (ASFV) causes severe disease in domestic pigs and wild boars, seriously threatening the development of the global pig industry. Type I interferon (IFN-I) is an important component of innate immunity, inducing the transcription and expression of antiviral cytokines by activating Janus-activated kinase-signal transducer and activator of transcription (STAT). However, the underlying molecular mechanisms by which ASFV antagonizes IFN-I signaling have not been fully elucidated. Therefore, using coimmunoprecipitation, confocal microscopy, and dual luciferase reporter assay methods, we investigated these mechanisms and identified a novel ASFV immunosuppressive protein, pB475L, which interacts with the C-terminal domain of STAT2. Consequently, pB475L inhibited IFN-I signaling by inhibiting STAT1 and STAT2 heterodimerization and nuclear translocation. Furthermore, we constructed an ASFV-B475L7PM mutant strain by homologous recombination, finding that ASFV-B475L7PM attenuated the inhibitory effects on IFN-I signaling compared to ASFV-WT. In summary, this study reveals a new mechanism by which ASFV impairs host innate immunity.

Mechanisms and therapeutic prospect of the JAK-STAT signaling pathway in liver cancer

Liver cancer (LC) poses a significant global health challenge due to its high incidence and poor prognosis. Current systemic treatment options, such as surgery, chemotherapy, radiofrequency ablation, and immunotherapy, have shown limited effectiveness for advanced LC patients. Moreover, owing to the heterogeneous nature of LC, it is crucial to uncover more in-depth pathogenic mechanisms and develop effective treatments to address the limitations of the existing therapeutic modalities. Increasing evidence has revealed the crucial role of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway in the pathogenesis of LC. The specific mechanisms driving the JAK-STAT pathway activation in LC, participate in a variety of malignant biological processes, including cell differentiation, evasion, anti-apoptosis, immune escape, and treatment resistance. Both preclinical and clinical investigations on the JAK-STAT pathway inhibitors have exhibited potential in LC treatment, thereby opening up avenues for the development of more targeted therapeutic strategies for LC. In this study, we provide an overview of the JAK-STAT pathway, delving into the composition, activation, and dynamic interplay within the pathway. Additionally, we focus on the molecular mechanisms driving the aberrant activation of the JAK-STAT pathway in LC. Furthermore, we summarize the latest advancements in targeting the JAK-STAT pathway for LC treatment. The insights presented in this review aim to underscore the necessity of research into the JAK-STAT signaling pathway as a promising avenue for LC therapy.

Exploring Novel Frontiers: Leveraging STAT3 Signaling for Advanced Cancer Therapeutics

Signal Transducer and Activator of Transcription 3 (STAT3) plays a significant role in diverse physiologic processes, including cell proliferation, differentiation, angiogenesis, and survival. STAT3 activation via phosphorylation of tyrosine and serine residues is a complex and tightly regulated process initiated by upstream signaling pathways with ligand binding to receptor and non-receptor-linked kinases. Through downstream deregulation of target genes, aberrations in STAT3 activation are implicated in tumorigenesis, metastasis, and recurrence in multiple cancers. While there have been extensive efforts to develop direct and indirect STAT3 inhibitors using novel drugs as a therapeutic strategy, direct clinical application remains in evolution. In this review, we outline the mechanisms of STAT3 activation, the resulting downstream effects in physiologic and malignant settings, and therapeutic strategies for targeting STAT3. We also summarize the pre-clinical and clinical evidence of novel drug therapies targeting STAT3 and discuss the challenges of establishing their therapeutic efficacy in the current clinical landscape.

Transcription factors in the development and treatment of immune disorders

Immune function is highly controlled at the transcriptional level by the binding of transcription factors (TFs) to promoter and enhancer elements. Several TF families play major roles in immune gene expression, including NF-κB, STAT, IRF, AP-1, NRs, and NFAT, which trigger anti-pathogen responses, promote cell differentiation, and maintain immune system homeostasis. Aberrant expression, activation, or sequence of isoforms and variants of these TFs can result in autoimmune and inflammatory diseases as well as hematological and solid tumor cancers. For this reason, TFs have become attractive drug targets, even though most were previously deemed "undruggable" due to their lack of small molecule binding pockets and the presence of intrinsically disordered regions. However, several aspects of TF structure and function can be targeted for therapeutic intervention, such as ligand-binding domains, protein-protein interactions between TFs and with cofactors, TF-DNA binding, TF stability, upstream signaling pathways, and TF expression. In this review, we provide an overview of each of the important TF families, how they function in immunity, and some related diseases they are involved in. Additionally, we discuss the ways of targeting TFs with drugs along with recent research developments in these areas and their clinical applications, followed by the advantages and disadvantages of targeting TFs for the treatment of immune disorders.

Generation of porcine PK-15 cells lacking the Ifnar1 or Stat2 gene to optimize the efficiency of viral isolation

Because pigs are intermediate or amplifying hosts for several zoonotic viruses, the pig-derived PK-15 cell line is an indispensable tool for studying viral pathogenicity and developing treatments, vaccines, and preventive measures to mitigate the risk of disease outbreaks. However, we must consider the possibility of contamination by type I interferons (IFNs), such as IFNα and IFNβ, or IFN-inducing substances, such as virus-derived double-stranded RNA or bacterial lipopolysaccharides, in clinical samples, leading to lower rates of viral isolation. In this study, we aimed to generate a PK-15 cell line that can be used to isolate viruses from clinical samples carrying a risk of contamination by IFN-inducing substances. To this end, we depleted the IFN alpha and beta receptor subunit 1 (Ifnar1) gene or signal transducer and activator of transcription 2 (Stat2) gene in PK-15 cells using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 method. Treatment of PK-15 cells lacking Ifnar1 or Stat2 with IFNβ or poly (I:C) resulted in no inhibitory effects on viral infection by a lentiviral vector, influenza virus, and Akabane virus. These results demonstrate that PK-15 cells lacking Ifnar1 or Stat2 could represent a valuable and promising tool for viral isolation, vaccine production, and virological investigations.

Structural comparison and expression function analysis of BF/C2 in Ctenopharyngodon idella and Squaliobarbus curriculus

Ctenopharyngodon idella and Squaliobarbus curriculus, members of the Cyprinidae family and Yaroideae subfamily, have shown different levels of resistance to grass carp reo virus (GCRV), with S. curriculus exhibiting higher resilience. In the pursuit to explore the distinctions in the structural and expression traits of BF/C2 (A,B) between the two species, we conducted an analysis involving the cloning and examination of various coding sequences (CDS). We successfully cloned the CDS of ci-BF/C2A and ci-BF/C2B from C. idella, which spanned 2259 bp and 2514 bp respectively, encoding 752 and 837 amino acids. Similarly, the CDS of sc-BF/C2A and sc-BF/C2B from S. curriculus were cloned, featuring lengths of 1353 bp and 2517 bp and encoding 450 and 838 amino acids, respectively. A chromosome collinearity assessment revealed that ci-BF/C2A demonstrated collinearity with sc-BF/C2A, a finding not replicated with ci-BF/C2B and sc-BF/C2B. Delving into gene structure, we discerned that ci-BF/C2A harbored a greater number of Tryp_SPc domains compared to sc-BF/C2A. Following this, we engineered and purified six prokaryotic recombinant proteins: CI-BF/C2A, CI-BF/C2A1 (a variant resulting from the deletion of the Tryp_SPc domain of CI-BF/C2A), CI-BF/C2A2 (representing the Tryp_SPc domain of CI-BF/C2A), CI-BF/C2B, SC-BF/C2A, and SC-BF/C2B. Through serum co-incubation tests with these recombinant proteins, we established the activation of the complement marker C3 in each case. Utilizing fluorescence quantitative expression analysis, we observed ubiquitous expression of ci-BF/C2A and ci-BF/C2B across all grass carp tissues, predominantly in the liver. This pattern mirrored in S. curriculus, where sc-BF/C2A was highly expressed in the gills, and sc-BF/C2B manifested notably in the liver. Kidney cell infection experiments on both species revealed enhanced resistance to GCRV post-incubation with the recombinant proteins. Notably, cells treated with SC-BF/C2 (A, B) exhibited pronounced resilience compared to those treated with CI-BF/C2 (A, B, A1, A2). However, cells incubated with CI-BF/C2A1 and CI-BF/C2A2 showed strengthen resistance relative to cells treated with CI-BF/C2A and CI-BF/C2B. In GCRV infection trials on grass carp, ci-BF/C2A and ci-BF/C2B expressions reached a zenith on the seventh day post-infection, highlighting a distinctive functional mode in immune defense against GCRV infection orchestrated by BF/C2. The empirical data underscores the pivotal role of the Tryp_SPc domain in immune responses to GCRV infection, pinpointing its influence on ci-BF/C2A expression. Conclusively, this investigation provides a foundational understanding of the unique immune function characteristics of BF/C2 in grass carp, paving the way for further scholarly exploration in this realm.

Modulation of JAK-STAT Signaling by LNK: A Forgotten Oncogenic Pathway in Hormone Receptor-Positive Breast Cancer

Breast cancer remains the most frequently diagnosed cancer in women worldwide. Tumors that express hormone receptors account for 75% of all cases. Understanding alternative signaling cascades is important for finding new therapeutic targets for hormone receptor-positive breast cancer patients. JAK-STAT signaling is commonly activated in hormone receptor-positive breast tumors, inducing inflammation, proliferation, migration, and treatment resistance in cancer cells. In hormone receptor-positive breast cancer, the JAK-STAT cascade is stimulated by hormones and cytokines, such as prolactin and IL-6. In normal cells, JAK-STAT is inhibited by the action of the adaptor protein, LNK. However, the role of LNK in breast tumors is not fully understood. This review compiles published reports on the expression and activation of the JAK-STAT pathway by IL-6 and prolactin and potential inhibition of the cascade by LNK in hormone receptor-positive breast cancer. Additionally, it includes analyses of available datasets to determine the level of expression of LNK and various members of the JAK-STAT family for the purpose of establishing associations between expression and clinical outcomes. Together, experimental evidence and in silico studies provide a better understanding of the potential implications of the JAK-STAT-LNK loop in hormone receptor-positive breast cancer progression.

African swine fever virus MGF-360-10L is a novel and crucial virulence factor that mediates ubiquitination and degradation of JAK1 by recruiting the E3 ubiquitin ligase HERC5

African swine fever virus (ASFV) causes acute hemorrhagic infectious disease in pigs. The ASFV genome encodes various proteins that enable the virus to escape innate immunity; however, the underlying mechanisms are poorly understood. The present study found that ASFV MGF-360-10L significantly inhibits interferon (IFN)-β-triggered STAT1/2 promoter activation and the production of downstream IFN-stimulated genes (ISGs). ASFV MGF-360-10L deletion (ASFV-Δ10L) replication was impaired compared with the parental ASFV CN/GS/2018 strain, and more ISGs were induced by the ASFV-Δ10L in porcine alveolar macrophages in vitro. We found that MGF-360-10L mainly targets JAK1 and mediates its degradation in a dose-dependent manner. Meanwhile, MGF-360-10L also mediates the K48-linked ubiquitination of JAK1 at lysine residues 245 and 269 by recruiting the E3 ubiquitin ligase HERC5 (HECT and RLD domain-containing E3 ubiquitin protein ligase 5). The virulence of ASFV-Δ10L was significantly lower than that of the parental strain in vivo, which indicates that MGF-360-10L is a novel virulence factor of ASFV. Our findings elaborate the novel mechanism of MGF-360-10L on the STAT1/2 signaling pathway, expanding our understanding of the inhibition of host innate immunity by ASFV-encoded proteins and providing novel insights that could contribute to the development of African swine fever vaccines. IMPORTANCE African swine fever outbreaks remain a concern in some areas. There is no effective drug or commercial vaccine to prevent African swine fever virus (ASFV) infection. In the present study, we found that overexpression of MGF-360-10L strongly inhibited the interferon (IFN)-β-induced STAT1/2 signaling pathway and the production of IFN-stimulated genes (ISGs). Furthermore, we demonstrated that MGF-360-10L mediates the degradation and K48-linked ubiquitination of JAK1 by recruiting the E3 ubiquitin ligase HERC5. The virulence of ASFV with MGF-360-10L deletion was significantly less than parental ASFV CN/GS/2018. Our study identified a new virulence factor and revealed a novel mechanism by which MGF-360-10L inhibits the immune response, thus providing new insights into the vaccination strategies against ASFV.

New Possible Ways to Use Exosomes in Diagnostics and Therapy via JAK/STAT Pathways

Exosomes have the potential to be the future of personalized diagnostics and therapy. They are nano-sized particles between 30 and 100 nm flowing in the extracellular milieu, where they mediate cell-cell communication and participate in immune system regulation. Tumor-derived exosomes (TDEs) secreted from different types of cancer cells are the key regulators of the tumor microenvironment. With their immune suppressive cargo, TDEs prevent the antitumor immune response, leading to reduced effectiveness of cancer treatment by promoting a pro-tumorigenic microenvironment. Involved signaling pathways take part in the regulation of tumor proliferation, differentiation, apoptosis, and angiogenesis. Signal transducers and activators of transcription factors (STATs) and Janus kinase (JAK) signaling pathways are crucial in malignancies and autoimmune diseases alike, and their potential to be manipulated is currently the focus of interest. In this review, we aim to discuss exosomes, TDEs, and the JAK/STAT pathways, along with mediators like interleukins, tripartite motif proteins, and interferons.

JAK/STAT Signaling and Cervical Cancer: From the Cell Surface to the Nucleus

The Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathway constitutes a rapid signaling module from the cell surface to the nucleus, and activates different cellular responses, such as proliferation, survival, migration, invasion, and inflammation. When the JAK/STAT pathway is altered, it contributes to cancer progression and metastasis. STAT proteins play a central role in developing cervical cancer, and inhibiting the JAK/STAT signaling may be necessary to induce tumor cell death. Several cancers show continuous activation of different STATs, including cervical cancer. The constitutive activation of STAT proteins is associated with a poor prognosis and overall survival. The human papillomavirus (HPV) oncoproteins E6 and E7 play an essential role in cervical cancer progression, and they activate the JAK/STAT pathway and other signals that induce proliferation, survival, and migration of cancer cells. Moreover, there is a crosstalk between the JAK/STAT signaling cascade with other signaling pathways, where a plethora of different proteins activate to induce gene transcription and cell responses that contribute to tumor growth. Therefore, inhibition of the JAK/STAT pathway shows promise as a new target in cancer treatment. In this review, we discuss the role of the JAK/STAT pathway components and the role of the HPV oncoproteins associated with cellular malignancy through the JAK/STAT proteins and other signaling pathways to induce tumor growth.

A family-wide assessment of latent STAT transcription factor interactions reveals divergent dimer repertoires

The conversion of STAT proteins from latent to active transcription factors is central to cytokine signalling. Triggered by their signal-induced tyrosine phosphorylation, it is the assembly of a range of cytokine-specific STAT homo- and heterodimers that marks a key step in the transition of hitherto latent proteins to transcription activators. In contrast, the constitutive self-assembly of latent STATs and how it relates to the functioning of activated STATs, is understood less well. To provide a more complete picture, we developed a co-localization-based assay and tested all 28 possible combinations of the seven unphosphorylated STAT (U-STAT) proteins in living cells. We identified five U-STAT homodimers -STAT1, STAT3, STAT4, STAT5A and STAT5B- and two heterodimers -STAT1:STAT2 and STAT5A:STAT5B- and performed semi-quantitative assessments of the forces and characterizations of binding interfaces that support them. One STAT protein -STAT6- was found to be monomeric. This comprehensive analysis of latent STAT self-assembly lays bare considerable structural and functional diversity in the ways that link STAT dimerization before and after activation.

African Swine Fever Virus MGF505-7R Interacts with Interferon Regulatory Factor 9 to Evade the Type I Interferon Signaling Pathway and Promote Viral Replication

African swine fever (ASF) is an acute and severe infectious disease caused by the ASF virus (ASFV). The mortality rate of ASF in pigs can reach 100%, causing huge economic losses to the pig industry. Here, we found that ASFV protein MGF505-7R inhibited the beta interferon (IFN-β)-mediated Janus-activated kinase-signal transducer and activation of transcription (JAK-STAT) signaling. Our results demonstrate that MGF505-7R inhibited interferon-stimulated gene factor 3 (ISGF3)-mediated IFN-stimulated response element (ISRE) promoter activity. Importantly, we observed that MGF505-7R inhibits ISGF3 heterotrimer formation by interacting with interferon regulatory factor 9 (IRF9) and inhibits the nuclear translocation of ISGF3. Moreover, to demonstrate the role of MGF505-7R in IFN-I signal transduction during ASFV infection, we constructed and evaluated ASFV-ΔMGF505-7R recombinant viruses. ASFV-ΔMGF505-7R restored STAT2 and STAT1 phosphorylation, alleviated the inhibition of ISGF3 nuclear translocation, and showed increased susceptibility to IFN-β, unlike the parental GZ201801 strain. In conclusion, our study shows that ASFV protein MGF505-7R plays a key role in evading IFN-I-mediated innate immunity, revealing a new mode of evasion for ASFV. IMPORTANCE ASF, caused by ASFV, is currently prevalent in Eurasia, with mortality rates reaching 100% in pigs. At present, there are no safe or effective vaccines against ASFV. In this study, we found that the ASFV protein MGF505-7R hinders IFN-β signaling by interacting with IRF9 and inhibiting the formation of ISGF3 heterotrimers. Of note, we demonstrated that MGF505-7R plays a role in the immune evasion of ASFV in infected hosts and that recombinant viruses alleviated the effect on type I IFN (IFN-I) signaling and exhibited increased susceptibility to IFN-β. This study provides a theoretical basis for developing vaccines against ASFV using strains with MGF505-7R gene deletions.

Design and syntheses of a bimolecular STING agonist based on the covalent STING antagonist

Cyclic GMP-AMP synthase and stimulator of interferon genes (cGAS-STING) signaling stimulators, an essential innate immunity component, monitor invading pathogen DNA and damaged self-DNA, making them an appealing target for drug development. The natural STING agonist, 2'3'-cGAMP, mounts and stabilizes the STING homodimer to trigger an antiviral or antitumor immune responses. However, cyclic-dinucleotide-based STING agonists show limited clinical effects owing to their short half-lives. To explore whether STING-dimer stabilizers could trigger STING signaling instead of cyclic dinucleotide-based molecules, we analyzed the structural characteristics of STING to design and synthesize a series of compounds based on the covalent STING inhibitor C-170, three of which were 23, 26, and 27, exhibited STING-dependent immune activation, both in vitro and in vivo. Compound 23 could act synergistically with cGAMP and other STING agonists as a promising moderate STING agonist. This indicates that promoting STING dimerization is a promising strategy for designing next-generation STING agonists.

IFN-Inducible SerpinA5 Triggers Antiviral Immunity by Regulating STAT1 Phosphorylation and Nuclear Translocation

Deeply understanding virus-host interactions is a prerequisite for developing effective strategies to control frequently emerging infectious diseases, which have become a serious challenge for global public health. The type I interferon (IFN)-mediated JAK/STAT pathway is well known for playing an essential role in host antiviral immunity, but the exact regulatory mechanisms of various IFN-stimulated genes (ISGs) are not yet fully understood. We herein reported that SerpinA5, as a novel ISG, played a previously unrecognized role in antiviral activity. Mechanistically, SerpinA5 can upregulate the phosphorylation of STAT1 and promote its nuclear translocation, thus effectively activating the transcription of IFN-related signaling pathways to impair viral infections. Our data provide insights into SerpinA5-mediated innate immune signaling during virus-host interactions.

Pellino3 ligase negatively regulates influenza B dependent RIG-I signalling through downregulation of TRAF3-mediated induction of the transcription factor IRF3 and IFNβ production

Viral infection activates the innate immune system, which recognizes viral components by a variety of pattern recognition receptors and initiates signalling cascades leading to the production of pro-inflammatory cytokines. To date, signalling cascades triggered after virus recognition are not fully characterized and are investigated by many research groups. The critical role of the E3 ubiquitin ligase Pellino3 in antibacterial and antiviral response is now widely accepted, but the precise mechanism remains elusive. In this study, we sought to explore Pellino3 role in the retinoic acid-inducible gene I (RIG-I)-dependent signalling pathway. In this work, the molecular mechanisms of the innate immune response, regulated by Pellino3, were investigated in lung epithelial cells during influenza B virus infection. We used wild-type and Pellino3-deficient A549 cells as model cell lines to examine the role of Pellino3 ligase in the type I interferon (IFN) signalling pathway. Our results indicate that Pellino3 is involved in direct ubiquitination and degradation of the TRAF3, suppressing interferon regulatory factor 3 (IRF3) activation and interferon beta (IFNβ) production.

Therapeutic modulation of JAK-STAT, mTOR, and PPAR-γ signaling in neurological dysfunctions

The cytokine-activated Janus kinase (JAK)-signal transducer and activator of transcription (STAT) cascade is a pleiotropic pathway that involves receptor subunit multimerization. The mammalian target of rapamycin (mTOR) is a ubiquitously expressed serine-threonine kinase that perceives and integrates a variety of intracellular and environmental stimuli to regulate essential activities such as cell development and metabolism. Peroxisome proliferator-activated receptor-gamma (PPARγ) is a prototypical metabolic nuclear receptor involved in neural differentiation and axon polarity. The JAK-STAT, mTOR, and PPARγ signaling pathways serve as a highly conserved signaling hub that coordinates neuronal activity and brain development. Additionally, overactivation of JAK/STAT, mTOR, and inhibition of PPARγ signaling have been linked to various neurocomplications, including neuroinflammation, apoptosis, and oxidative stress. Emerging research suggests that even minor disruptions in these cellular and molecular processes can have significant consequences manifested as neurological and neuropsychiatric diseases. Of interest, target modulators have been proven to alleviate neuronal complications associated with acute and chronic neurological deficits. This research-based review explores the therapeutic role of JAK-STAT, mTOR, and PPARγ signaling modulators in preventing neuronal dysfunctions in preclinical and clinical investigations.

Type I interferon signaling facilitates resolution of acute liver injury by priming macrophage polarization

Due to their broad functional plasticity, myeloid cells contribute to both liver injury and recovery during acetaminophen overdose-induced acute liver injury (APAP-ALI). A comprehensive understanding of cellular diversity and intercellular crosstalk is essential to elucidate the mechanisms and to develop therapeutic strategies for APAP-ALI treatment. Here, we identified the function of IFN-I in the myeloid compartment during APAP-ALI. Utilizing single-cell RNA sequencing, we characterized the cellular atlas and dynamic progression of liver CD11b+ cells post APAP-ALI in WT and STAT2 T403A mice, which was further validated by immunofluorescence staining, bulk RNA-seq, and functional experiments in vitro and in vivo. We identified IFN-I-dependent transcriptional programs in a three-way communication pathway that involved IFN-I synthesis in intermediate restorative macrophages, leading to CSF-1 production in aging neutrophils that ultimately enabled Trem2+ restorative macrophage maturation, contributing to efficient liver repair. Overall, we uncovered the heterogeneity of hepatic myeloid cells in APAP-ALI at single-cell resolution and the therapeutic potential of IFN-I in the treatment of APAP-ALI.

Low COVID-19 vaccine coverage and guardian acceptance among pediatric transplant recipients

To investigate COVID-19 vaccine coverage in immunosuppressed children, assess guardians' intention to vaccinate children, and determine reasons and associated factors. In addition, we attempted to capture the characteristics of them with Omicron. We obtained the vaccination coverage and guardian vaccine acceptance among pediatric transplant recipients through a web-based questionnaire conducted from April 12 to 28, 2022, and performed the statistical analysis. Seven organ transplant recipient children with Omicron were also clinically analyzed. The three-dose vaccine coverage for liver transplant (n = 563) and hematopoietic stem cell transplantation (n = 122) recipient children was 0.9% and 4.9%, and guardian vaccine acceptance was 63.8%. Independent risk factors for vaccine acceptance were the child's age, geographic location, type of transplant, guardian's vaccination status, guardian's level of distress about epidemic events, guardian's risk perception ability, anxiety, and knowledge of epidemic control. The main reasons for vaccine hesitancy were fear of vaccine-induced adverse events and doubts about efficacy. Ultimately, most children infected with Omicron have mild or no symptoms and are infected by intra-family. Since vaccine coverage and guardian acceptance are lowest among liver transplant children, and the infected are mainly intra-family, we should devise more targeted education and vaccination instructions for their guardians.

How cancer cells make and respond to interferon-I

Acute exposure of cancer cells to high concentrations of type I interferon (IFN-I) drives growth arrest and apoptosis, whereas chronic exposure to low concentrations provides important prosurvival advantages. Tyrosine-phosphorylated IFN-stimulated gene (ISG) factor 3 (ISGF3) drives acute deleterious responses to IFN-I, whereas unphosphorylated (U-)ISGF3, lacking tyrosine phosphorylation, drives essential constitutive prosurvival mechanisms. Surprisingly, programmed cell death-ligand 1 (PD-L1), often expressed on the surfaces of tumor cells and well recognized for its importance in inactivating cytotoxic T cells, also has important cell-intrinsic protumor activities, including dampening acute responses to cytotoxic high levels of IFN-I and sustaining the expression of the low levels that benefit tumors. More thorough understanding of the newly recognized complex roles of IFN-I in cancer may lead to the identification of novel therapeutic strategies.

Molecular cloning, expression and functional analysis of STAT2 in orange-spotted grouper, Epinephelus coioides

Signal transducer and activator of transcription 2 (STAT2) is an important molecule involved in the type I interferon signaling pathway. To better understand the functions of STAT2 in fish immune response, a STAT2 gene from orange-spotted grouper (Epinephelus coioides) (EcSTAT2) was cloned and characterized in this study. EcSTAT2 encoded a 802-amino acid peptide which shared 99.5% and 91.5% identity with giant grouper (Epinephelus lanceolatus) and leopard coral grouper (Plectropomus leopardus), respectively. Amino acid alignment analysis showed that EcSTAT2 contained five conserved domains, including N-terminal protein interaction domain, coiled coil domain (CCD), DNA binding domain (DBD), Src-homology 2 (SH2) domain, and C-terminal transactivation domain (TAD). Phylogenetic analysis indicated that EcSTAT2 clustered into fish STAT2 group and showed the nearest relationship to giant grouper STAT2. In healthy grouper, EcSTAT2 was distributed in all tissues tested, and the expression of EcSTAT2 was predominantly detected in spleen, kidney and gill. In vitro, EcSTAT2 expression was significantly increased in response to polyinosinic:polycytidylic acid [poly (I:C)] stimulation and red-spotted grouper nervous necrosis virus (RGNNV) infection. Subcellular localization showed that EcSTAT2 was located in the cytoplasm in a punctate manner. EcSTAT2 overexpression significantly inhibited RGNNV replication, as evidenced by the decreased severity of cytopathic effect (CPE) and the reduced expression levels of viral genes and protein. Consistently, knockdown of EcSTAT2 using small interfering RNA (siRNA) promoted RGNNV replication. Furthermore, EcSTAT2 overexpression increased both interferon (IFN) and interferon stimulated genes (ISGs) expression. In addition, EcSTAT2 knockdown decreased the transcription levels of IFN and ISGs. Together, our data demonstrated that EcSTAT2 exerted antiviral activity against RGNNV through up-regulation of host interferon response.

The JAK-STAT pathway at 30: Much learned, much more to do

The discovery of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway arose from investigations of how cells respond to interferons (IFNs), revealing a paradigm in cell signaling conserved from slime molds to mammals. These discoveries revealed mechanisms underlying rapid gene expression mediated by a wide variety of extracellular polypeptides including cytokines, interleukins, and related factors. This knowledge has provided numerous insights into human disease, from immune deficiencies to cancer, and was rapidly translated to new drugs for autoimmune, allergic, and infectious diseases, including COVID-19. Despite these advances, major challenges and opportunities remain.

IFI44 is an immune evasion biomarker for SARS-CoV-2 and Staphylococcus aureus infection in patients with RA

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic of severe coronavirus disease 2019 (COVID-19). Staphylococcus aureus is one of the most common pathogenic bacteria in humans, rheumatoid arthritis (RA) is among the most prevalent autoimmune conditions. RA is a significant risk factor for SARS-CoV-2 and S. aureus infections, although the mechanism of RA and SARS-CoV-2 infection in conjunction with S. aureus infection has not been elucidated. The purpose of this study is to investigate the biomarkers and disease targets between RA and SARS-CoV-2 and S. aureus infections using bioinformatics analysis, to search for the molecular mechanisms of SARS-CoV-2 and S. aureus immune escape and potential drug targets in the RA population, and to provide new directions for further analysis and targeted development of clinical treatments.

Methods

The RA dataset (GSE93272) and the S. aureus bacteremia (SAB) dataset (GSE33341) were used to obtain differentially expressed gene sets, respectively, and the common differentially expressed genes (DEGs) were determined through the intersection. Functional enrichment analysis utilizing GO, KEGG, and ClueGO methods. The PPI network was created utilizing the STRING database, and the top 10 hub genes were identified and further examined for functional enrichment using Metascape and GeneMANIA. The top 10 hub genes were intersected with the SARS-CoV-2 gene pool to identify five hub genes shared by RA, COVID-19, and SAB, and functional enrichment analysis was conducted using Metascape and GeneMANIA. Using the NetworkAnalyst platform, TF-hub gene and miRNA-hub gene networks were built for these five hub genes. The hub gene was verified utilizing GSE17755, GSE55235, and GSE13670, and its effectiveness was assessed utilizing ROC curves. CIBERSORT was applied to examine immune cell infiltration and the link between the hub gene and immune cells.

Results

A total of 199 DEGs were extracted from the GSE93272 and GSE33341 datasets. KEGG analysis of enrichment pathways were NLR signaling pathway, cell membrane DNA sensing pathway, oxidative phosphorylation, and viral infection. Positive/negative regulation of the immune system, regulation of the interferon-I (IFN-I; IFN-α/β) pathway, and associated pathways of the immunological response to viruses were enriched in GO and ClueGO analyses. PPI network and Cytoscape platform identified the top 10 hub genes: RSAD2, IFIT3, GBP1, RTP4, IFI44, OAS1, IFI44L, ISG15, HERC5, and IFIT5. The pathways are mainly enriched in response to viral and bacterial infection, IFN signaling, and 1,25-dihydroxy vitamin D3. IFI44, OAS1, IFI44L, ISG15, and HERC5 are the five hub genes shared by RA, COVID-19, and SAB. The pathways are primarily enriched for response to viral and bacterial infections. The TF-hub gene network and miRNA-hub gene network identified YY1 as a key TF and hsa-mir-1-3p and hsa-mir-146a-5p as two important miRNAs related to IFI44. IFI44 was identified as a hub gene by validating GSE17755, GSE55235, and GSE13670. Immune cell infiltration analysis showed a strong positive correlation between activated dendritic cells and IFI44 expression.

Conclusions

IFI144 was discovered as a shared biomarker and disease target for RA, COVID-19, and SAB by this study. IFI44 negatively regulates the IFN signaling pathway to promote viral replication and bacterial proliferation and is an important molecular target for SARS-CoV-2 and S. aureus immune escape in RA. Dendritic cells play an important role in this process. 1,25-Dihydroxy vitamin D3 may be an important therapeutic agent in treating RA with SARS-CoV-2 and S. aureus infections.

Exposing the Two Contrasting Faces of STAT2 in Inflammation

Inflammation is a natural immune defense mechanism of the body's response to injury, infection, and other damaging triggers. Uncontrolled inflammation may become chronic and contribute to a range of chronic inflammatory diseases. Signal transducer and activator of transcription 2 (STAT2) is an essential transcription factor exclusive to type I and type III interferon (IFN) signaling pathways. Both pathways are involved in multiple biological processes, including powering the immune system as a means of controlling infection that must be tightly regulated to offset the development of persistent inflammation. While studies depict STAT2 as protective in promoting host defense, new evidence is accumulating that exposes the deleterious side of STAT2 when inappropriately regulated, thus prompting its reevaluation as a signaling molecule with detrimental effects in human disease. This review aims to provide a comprehensive summary of the findings based on literature regarding the inflammatory behavior of STAT2 in microbial infections, cancer, autoimmune, and inflammatory diseases. In conveying the extent of our knowledge of STAT2 as a proinflammatory mediator, the aim of this review is to stimulate further investigations into the role of STAT2 in diseases characterized by deregulated inflammation and the mechanisms responsible for triggering severe responses.

Interferon‐mediated repression of miR ‐324‐5p potentiates necroptosis to facilitate antiviral defense

Mixed lineage kinase domain‐like protein (MLKL) is the terminal effector of necroptosis, a form of regulated necrosis. Optimal activation of necroptosis, which eliminates infected cells, is critical for antiviral host defense. MicroRNAs (miRNAs) regulate the expression of genes involved in various biological and pathological processes. However, the roles of miRNAs in necroptosis‐associated host defense remain largely unknown. We screened a library of miRNAs and identified miR‐324‐5p as the most effective suppressor of necroptosis. MiR‐324‐5p downregulates human MLKL expression by specifically targeting the 3′UTR in a seed region‐independent manner. In response to interferons (IFNs), miR‐324‐5p is downregulated via the JAK/STAT signaling pathway, which removes the posttranscriptional suppression of MLKL mRNA and facilitates the activation of necroptosis. In influenza A virus (IAV)‐infected human primary macrophages, IFNs are induced, leading to the downregulation of miR‐324‐5p. MiR‐324‐5p overexpression attenuates IAV‐associated necroptosis and enhances viral replication, whereas deletion of miR‐324‐5p potentiates necroptosis and suppresses viral replication. Hence, miR‐324‐5p negatively regulates necroptosis by manipulating MLKL expression, and its downregulation by IFNs orchestrates optimal activation of necroptosis in host antiviral defense.

Human Platelet Lysate Induces Antiviral Responses against Parechovirus A3

Human platelet lysate (hPL) contains abundant growth factors for inducing human cell proliferation and may be a suitable alternative to fetal bovine serum (FBS) as a culture medium supplement. However, the application of hPL in virological research remains blank. Parechovirus type-A3 (PeV-A3) belongs to Picornaviridae, which causes meningoencephalitis in infants and young children. To understand the suitability of hPL-cultured cells for PeV-A3 infection, the infection of PeV-A3 in both FBS- and hPL-cultured glioblastoma (GBM) cells were compared. Results showed reduced PeV-A3 infection in hPL-cultured cells compared with FBS-maintained cells. Mechanistic analysis revealed hPL stimulating type I interferon (IFN) antiviral pathway, through which phospho-signal transducer and activator of transcription 1 (STAT1), STAT2, interferon regulatory factor 3 (IRF3) were activated and antiviral genes, such as IFN-α, IFN-β, and Myxovirus resistance protein 1 (MxA), were also detected. In addition, an enhanced PeV-A3 replication was detected in the hPL-cultured GBM cells treated with STAT-1 inhibitor (fludarabine) and STAT1 shRNA. These results in vitro suggested an unexpected effect of hPL-activated type I IFN pathway response to restrict virus replication and that hPL may be a potential antiviral bioreagent.

Current Strategies in Treating Cytokine Release Syndrome Triggered by Coronavirus SARS-CoV-2

Since the beginning of the SARS-CoV-2 pandemic, the treatments and management of the deadly COVID-19 disease have made great progress. The strategies for developing novel treatments against COVID-19 include antiviral small molecule drugs, cell and gene therapies, immunomodulators, neutralizing antibodies, and combination therapies. Among them, immunomodulators are the most studied treatments. The small molecule antiviral drugs and immunoregulators are expected to be effective against viral variants of SARS-CoV-2 as these drugs target either conservative parts of the virus or common pathways of inflammation. Although the immunoregulators have shown benefits in reducing mortality of cytokine release syndrome (CRS) triggered by SARS-CoV-2 infections, extensive investigations on this class of treatment to launch novel therapies that substantially improve efficacy and reduce side effects are still warranted. Moreover, great challenges have emerged as the SARS-CoV-2 virus quickly, frequently, and continuously evolved. This review provides an update and summarizes the recent advances in the treatment of COVID-19 and in particular emphasized the strategies in managing CRS triggered by SARS-CoV-2. A brief perspective in the battle against the deadly disease was also provided.

Inhibition of Histone H3 Lysine-27 Demethylase Activity Relieves Rheumatoid Arthritis Symptoms via Repression of IL6 Transcription in Macrophages

Rheumatoid arthritis (RA) occurs in about 5 per 1,000 people and can lead to severe joint damage and disability. However, the knowledge of pathogenesis and treatment for RA remains limited. Here, we found that histone demethylase inhibitor GSK-J4 relieved collagen induced arthritis (CIA) symptom in experimental mice model, and the underlying mechanism is related to epigenetic transcriptional regulation in macrophages. The role of epigenetic regulation has been introduced in the process of macrophage polarization and the pathogenesis of inflammatory diseases. As a repressive epigenetic marker, tri-methylation of lysine 27 on histone H3 (H3K27me3) was shown to be important for transcriptional gene expression regulation. Here, we comprehensively analyzed H3K27me3 binding promoter and corresponding genes function by RNA sequencing in two differentially polarized macrophage populations. The results revealed that H3K27me3 binds on the promoter regions of multiple critical cytokine genes and suppressed their transcription, such as IL6, specifically in M-CSF derived macrophages but not GM-CSF derived counterparts. Our results may provide a new approach for the treatment of inflammatory and autoimmune disorders.

Repurposing Multiple-Molecule Drugs for COVID-19-Associated Acute Respiratory Distress Syndrome and Non-Viral Acute Respiratory Distress Syndrome via a Systems Biology Approach and a DNN-DTI Model Based on Five Drug Design Specifications

The coronavirus disease 2019 (COVID-19) epidemic is currently raging around the world at a rapid speed. Among COVID-19 patients, SARS-CoV-2-associated acute respiratory distress syndrome (ARDS) is the main contribution to the high ratio of morbidity and mortality. However, clinical manifestations between SARS-CoV-2-associated ARDS and non-SARS-CoV-2-associated ARDS are quite common, and their therapeutic treatments are limited because the intricated pathophysiology having been not fully understood. In this study, to investigate the pathogenic mechanism of SARS-CoV-2-associated ARDS and non-SARS-CoV-2-associated ARDS, first, we constructed a candidate host-pathogen interspecies genome-wide genetic and epigenetic network (HPI-GWGEN) via database mining. With the help of host-pathogen RNA sequencing (RNA-Seq) data, real HPI-GWGEN of COVID-19-associated ARDS and non-viral ARDS were obtained by system modeling, system identification, and Akaike information criterion (AIC) model order selection method to delete the false positives in candidate HPI-GWGEN. For the convenience of mitigation, the principal network projection (PNP) approach is utilized to extract core HPI-GWGEN, and then the corresponding core signaling pathways of COVID-19-associated ARDS and non-viral ARDS are annotated via their core HPI-GWGEN by KEGG pathways. In order to design multiple-molecule drugs of COVID-19-associated ARDS and non-viral ARDS, we identified essential biomarkers as drug targets of pathogenesis by comparing the core signal pathways between COVID-19-associated ARDS and non-viral ARDS. The deep neural network of the drug–target interaction (DNN-DTI) model could be trained by drug–target interaction databases in advance to predict candidate drugs for the identified biomarkers. We further narrowed down these predicted drug candidates to repurpose potential multiple-molecule drugs by the filters of drug design specifications, including regulation ability, sensitivity, excretion, toxicity, and drug-likeness. Taken together, we not only enlighten the etiologic mechanisms under COVID-19-associated ARDS and non-viral ARDS but also provide novel therapeutic options for COVID-19-associated ARDS and non-viral ARDS.

Poxviruses and paramyxoviruses use a conserved mechanism of STAT1 antagonism to inhibit interferon signaling

The induction of interferon (IFN)-stimulated genes by STATs is a critical host defense mechanism against virus infection. Here, we report that a highly expressed poxvirus protein, 018, inhibits IFN-induced signaling by binding to the SH2 domain of STAT1, thereby preventing the association of STAT1 with an activated IFN receptor. Despite encoding other inhibitors of IFN-induced signaling, a poxvirus mutant lacking 018 was attenuated in mice. The 2.0 Å crystal structure of the 018:STAT1 complex reveals a phosphotyrosine-independent mode of 018 binding to the SH2 domain of STAT1. Moreover, the STAT1-binding motif of 018 shows similarity to the STAT1-binding proteins from Nipah virus, which, similar to 018, block the association of STAT1 with an IFN receptor. Overall, these results uncover a conserved mechanism of STAT1 antagonism that is employed independently by distinct virus families.

The JAK/STAT signaling pathway: from bench to clinic

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway was discovered more than a quarter-century ago. As a fulcrum of many vital cellular processes, the JAK/STAT pathway constitutes a rapid membrane-to-nucleus signaling module and induces the expression of various critical mediators of cancer and inflammation. Growing evidence suggests that dysregulation of the JAK/STAT pathway is associated with various cancers and autoimmune diseases. In this review, we discuss the current knowledge about the composition, activation, and regulation of the JAK/STAT pathway. Moreover, we highlight the role of the JAK/STAT pathway and its inhibitors in various diseases.

The JAK/STAT signaling pathway: from bench to clinic

The Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway was discovered more than a quarter-century ago. As a fulcrum of many vital cellular processes, the JAK/STAT pathway constitutes a rapid membrane-to-nucleus signaling module and induces the expression of various critical mediators of cancer and inflammation. Growing evidence suggests that dysregulation of the JAK/STAT pathway is associated with various cancers and autoimmune diseases. In this review, we discuss the current knowledge about the composition, activation, and regulation of the JAK/STAT pathway. Moreover, we highlight the role of the JAK/STAT pathway and its inhibitors in various diseases.

Human Disease Phenotypes Associated with Loss and Gain of Function Mutations in STAT2: Viral Susceptibility and Type I Interferonopathy

STAT2 is distinguished from other STAT family members by its exclusive involvement in type I and III interferon (IFN-I/III) signaling pathways, and its unique behavior as both positive and negative regulator of IFN-I signaling. The clinical relevance of these opposing STAT2 functions is exemplified by monogenic diseases of STAT2. Autosomal recessive STAT2 deficiency results in heightened susceptibility to severe and/or recurrent viral disease, whereas homozygous missense substitution of the STAT2-R148 residue is associated with severe type I interferonopathy due to loss of STAT2 negative regulation. Here we review the clinical presentation, pathogenesis, and management of these disorders of STAT2.