IFNAR1 and IFNAR2 play distinct roles in initiating type I interferon-induced JAK-STAT signaling and activating STATs

Identification of a type I IFN- and IRF-inducible enhancer in the 5'-UTR intron of MAVS in large yellow croaker Larimichthys crocea

The mitochondrial antiviral signaling protein (MAVS) relays signals from RIG-I-like receptors (RLRs) to induce type I interferon (IFN) production. In teleost fish, MAVS expression is significantly upregulated in response to viral infections or synthetic double-stranded RNA (dsRNA), whereas mammalian MAVS does not exhibit a similar response. However, the mechanisms regulating MAVS expression in teleosts remain unclear. In this study, we demonstrate that the viral mimic poly(I:C)-induced upregulation of Larimichthys crocea (Lc) MAVS occurs via the type I IFN signaling pathway. Inhibition of the JAK-STAT pathway significantly suppressed both poly(I:C)- and LcIFNi-induced LcMAVS expression. Further analysis revealed that an enhancer in the 5'- untranslated region (UTR) intron of LcMAVS contains two functional interferon-stimulated response elements (ISREs), which are crucial for its activation. The enhancer activity of LcMAVS is regulated by interferon regulatory factors (IRFs), including IRF1, IRF3, IRF7, IRF9, and IRF11. These IRFs form several heterodimeric complexes, such as IRF1/3, IRF1/7, IRF3/7, and IRF3/11, to mediate LcMAVS enhancer activation. Structural analysis indicates that the ISRE motifs in the intronic enhancer can accommodate two or three DNA-binding domains (DBDs) from IRFs. These findings provide a potential explanation for the differential regulation of MAVS in response to stimuli in teleosts and mammals. Furthermore, our study demonstrates that MAVS is an interferon-stimulated gene (ISG) in a marine fish, providing insights into the evolutionary divergence of the vertebrate RLR signaling pathway.

Human papillomavirus E1 proteins inhibit RIG-I/MDA5-MAVS, TLR3-TRIF, cGAS-STING, and JAK-STAT signaling pathways to evade innate antiviral immunity

Human papillomavirus (HPV) is a major etiological agent of both malignant and benign lesions, with high-risk types, such as HPV16 and HPV18, being strongly linked to cervical cancer, while low-risk types like HPV11 are associated with benign conditions. While viral proteins such as E6 and E7 are well-established regulators of immune evasion, the role of E1 in modulating the host antiviral responses remains insufficiently characterized. This study investigates the immunomodulatory functions of HPV16 and HPV11 E1 in suppressing innate antiviral immune signaling pathways. Through a combination of RT-qPCR and luciferase reporter assays, we demonstrate that E1 suppresses the production of interferons and interferon-stimulated genes triggered by viral infections and the activation of RIG-I/MDA5-MAVS, TLR3-TRIF, cGAS-STING, and JAK-STAT pathways. Co-immunoprecipitation assays reveal that E1 interacts directly with key signaling molecules within these pathways. E1 also impairs TBK1 and IRF3 phosphorylation and obstructs the nuclear translocation of IRF3, thereby broadly suppressing IFN responses. Additionally, E1 disrupts the JAK-STAT pathway by binding STAT1, which prevents the assembly and nuclear localization of the ISGF3 complex containing STAT1, STAT2, and IRF9, thereby further diminishing antiviral response. These findings establish E1 as a pivotal regulator of immune evasion and suggest its potential as a novel therapeutic target to enhance antiviral immunity in HPV-associated diseases.

Alternative splicing landscape in mouse skeletal muscle and adipose tissue: Effects of intermittent fasting and exercise

Alternative splicing contributes to diversify the cellular protein landscape, but aberrant splicing is implicated in many diseases. To which extent mis-splicing contributes to insulin resistance as the causal defect of type 2 diabetes and whether this can be reversed by lifestyle interventions is largely unknown. Therefore, RNA sequencing data from skeletal muscle and adipose tissue of diabetes-susceptible NZO mice treated with or without intermittent fasting and of healthy C57BL/6J mice subjected to exercise were analyzed for alternative splicing differences using Whippet and rMATS. Diet and exercise interventions triggered comparable levels of splicing changes, although the splicing profile of skeletal muscle appeared to be more flexible than that of adipose tissue, with 72-114 differential splicing events in muscle and less than 25 in adipose tissue. Splicing changes induced by time-restricted feeding, alternate-day fasting and exercise were generally mild, with a maximal percent spliced in (PSI) difference of 67%, indicating that alternative splicing plays a rather minor role in lifestyle-induced adaptations of muscle and adipose tissue in mice. However, intron retention contributed to the regulation of gene expression, influencing genes whose expression was directly linked to phenotypic parameters (e.g. Eno2 and Pan2). Alternate-day fasting promoted skipping of exon 7 in Mlxipl (coding for ChREBP), thereby affecting the glucose sensing module of this carbohydrate-responsive transcription factor. Both intermittent fasting and exercise training led to alternative splicing of known diabetes-related GWAS genes (e.g. Abcc8, Ifnar2, Smarcad1), highlighting the potential metabolic relevance of these changes.

The antiviral activity of myricetin against pseudorabies virus through regulation of the type I interferon signaling pathway

The type I interferon signaling pathway constitutes a pivotal component of the innate immune response, encompassing the cGAS/STING and JAK/STAT pathways. Drugs that affect the body's innate immune response could potentially be used as broad-spectrum antivirals. In this study, the antiviral activities of 25 flavonoids against pseudorabies virus (PRV) were tested in PK-15 cells. Eight active flavonoids were identified, with IC50 values ranging from 23.24 to 323.09 µM. Subsequently, the regulatory effects of these flavonoids on the cGAS/STING pathway in PRV-infected cells were investigated. It was found that Myricetin significantly increased the transcriptional levels of cGAS, STING, IRF3, and IFN-β, which had been reduced by PRV infection. The regulation of the type I interferon signaling pathways by myricetin following PRV infection was further investigated through the production of cGAMP and the assessment of transcriptional and protein levels of pivotal genes and proteins. To confirm the activation of the innate immune response, a dual luciferase gene reporter study found that the expression of the IFN-β promoter in the myricetin-treated group was significantly elevated in a cellular model of type I interferon signaling pathway, and the contents of IFN-β were also significantly higher than those observed in the infected-untreated group in a PRV-infected mice model. Moreover, the transcriptional and protein levels of key genes and proteins in cell and mouse models exhibited analogous outcomes to those observed in PRV-infected cells. These findings suggest that myricetin can effectively activate the type I interferon signaling pathway, thereby enhancing the innate immune response during PRV infection.

IMPORTANCE

PRV, belonging to the Herpesviridae family, is an easily overlooked zoonotic pathogen that can threaten human health. The immunoprotective efficacy of conventional vaccines is significantly reduced due to the continuous mutation of the PRV genome, which constantly generates new viral strains. Therefore, there is a need to develop potent therapeutic drugs. PRV is capable of evading the host's natural immunity by suppressing the host's type I interferon signaling pathway, and the search for drugs that activate natural immunity can induce the body to produce type I IFN interferon and exert antiviral effects. Accordingly, the present study sought to identify active compounds from flavonoids that modulate the type I IFN interferon signaling pathway and thus inhibit the proliferation of PRV, which provides a new idea for the development of anti-PRV drugs from flavonoids that modulate the type I IFN interferon signaling pathway to enhance the body's antiviral immunity.

Classical Swine Fever Virus Envelope Glycoproteins Erns, E1, and E2 Activate IL-10-STAT1-MX1/OAS1 Antiviral Pathway via Replacing Classical IFNα/β

Classical swine fever (CSF) is an acute and often fatal disease caused by CSF virus (CSFV) infection. In the present study, we investigated the transcriptional profiles of peripheral blood mononuclear cells (PBMCs) in pigs infected with CSFV. The results revealed that CSFV inhibits IFNα/β production, but up-regulates the expression of signal transducer and activator of transcription 1 (STAT1); this result was verified in vitro. Interestingly, STAT1 is typically a downstream target of IFNα/β, raising the question of how CSFV can inhibit IFNα/β expression, yet up-regulate STAT1 expression. To explore this further, we observed that UV-treated CSFV induced STAT1 expression. Our results demonstrated that CSFV Erns, E1, and E2 could up-regulate STAT1 expression within the host cell cytoplasm and facilitate its translocation into the nucleus. The Erns, E1, and E2 proteins also separately induced the up-regulation of interleukin (IL)-10; IL-10 acts as the communicator connecting Erns, E1, and E2 proteins to STAT1, leading to the subsequent up-regulation, phosphorylation, and nuclear translocation of STAT1. Silencing of IL-10 down-regulated STAT1 expression. Finally, MX1 and OAS1 were identified as downstream targets of the IL-10-STAT1 pathway. In summary, a novel IL-10-STAT1 pathway independent of IFNα/β induced by CSFV Erns, E1, and E2 was identified in this study.

Tp53 determines the spatial dynamics of M1/M2 tumor-associated macrophages and M1-driven tumoricidal effects

The spatial role of M1 and M2 tumor-associated macrophages (M1/M2 TAMs) in precision medicine remains unclear. EGFR and TP53 are among the most frequently mutated genes in lung adenocarcinoma. We characterized the mutation status and density of M1/M2 TAMs within tumor islets and stroma in 117 lung adenocarcinomas using next-generation sequencing and immunohistochemistry, respectively. Stromal M1 TAMs were positively correlated with disease progression and smoking history. In contrast, islet M1/M2 TAMs were predominantly found in tumors with wild-type TP53 (wtp53) but not associated with EGFR status. The presence of wtp53 was associated with the spatial distribution of M1/M2 TAMs in tumor islets and stroma. Additionally, dominance of islet M1 TAMs and M1-signature were significantly associated with improved survival in patients with wtp53 lung adenocarcinoma, unlike in those with mutant TP53. Conditioned medium from M1 macrophages (M1 CM) induced apoptosis in wtp53 cells through increased p53 accumulation. We found that interferons in M1 CM activate JAK1/TYK2 via IFNARs, leading to enhanced STAT1 expression and Y701 phosphorylation. This activation facilitates p53-STAT1 interactions, reduces the interaction between p53 and MDM2, and subsequently decreases p53 ubiquitination. M1 CM inhibited tumorigenesis, and silencing p53 reduced the anti-tumor efficacy of polyinosinic:polycytidylic acid (poly I:C) in vivo. Furthermore, higher M1-signature was significantly associated with better responses and survival following anti-PD1 treatment in wtp53 melanomas. IFNs/STAT1/p53 signaling was critical for the anti-tumor activity of M1 macrophages. These findings suggest that p53 modulates the spatial balance of M1/M2 TAMs, and the tumoricidal effects of M1 TAMs depend on p53 status. Thus, p53 companion diagnostics could facilitate the development of M1-oriented therapies, which may be particularly beneficial for wtp53 patients when combined with immunotherapy.

Regulation of human interferon signaling by transposon exonization

Innate immune signaling is essential for clearing pathogens and damaged cells and must be tightly regulated to avoid excessive inflammation or autoimmunity. Here, we found that the alternative splicing of exons derived from transposable elements is a key mechanism controlling immune signaling in human cells. By analyzing long-read transcriptome datasets, we identified numerous transposon exonization events predicted to generate functional protein variants of immune genes, including the type I interferon receptor IFNAR2. We demonstrated that the transposon-derived isoform of IFNAR2 is more highly expressed than the canonical isoform in almost all tissues and functions as a decoy receptor that potently inhibits interferon signaling, including in cells infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our findings uncover a primate-specific axis controlling interferon signaling and show how a transposon exonization event can be co-opted for immune regulation.

Widespread gene-environment interactions shape the immune response to SARS-CoV-2 infection in hospitalized COVID-19 patients

Genome-wide association studies performed in patients with coronavirus disease 2019 (COVID-19) have uncovered various loci significantly associated with susceptibility to SARS-CoV-2 infection and COVID-19 disease severity. However, the underlying cis-regulatory genetic factors that contribute to heterogeneity in the response to SARS-CoV-2 infection and their impact on clinical phenotypes remain enigmatic. Here, we used single-cell RNA-sequencing to quantify genetic contributions to cis-regulatory variation in 361,119 peripheral blood mononuclear cells across 63 COVID-19 patients during acute infection, 39 samples collected in the convalescent phase, and 106 healthy controls. Expression quantitative trait loci (eQTL) mapping across cell types within each disease state group revealed thousands of cis-associated variants, of which hundreds were detected exclusively in immune cells derived from acute COVID-19 patients. Patient-specific genetic effects dissipated as infection resolved, suggesting that distinct gene regulatory networks are at play in the active infection state. Further, 17.2% of tested loci demonstrated significant cell state interactions with genotype, with pathways related to interferon responses and oxidative phosphorylation showing pronounced cell state-dependent variation, predominantly in CD14+ monocytes. Overall, we estimate that 25.6% of tested genes exhibit gene-environment interaction effects, highlighting the importance of environmental modifiers in the transcriptional regulation of the immune response to SARS-CoV-2. Our findings underscore the importance of expanding the study of regulatory variation to relevant cell types and disease contexts and argue for the existence of extensive gene-environment effects among patients responding to an infection.

Promiscuous Janus kinase binding to cytokine receptors modulates signaling efficiencies and contributes to cytokine pleiotropy

Janus kinases (JAKs) bind to class I and II cytokine receptors, activating signaling and regulating gene transcription through signal transducer and activator of transcription (STAT) proteins. Type I interferons (IFNs) require the JAK members TYK2 and JAK1, which bind to the receptor subunits IFNAR1 and IFNAR2, respectively. We investigated the role of JAKs in regulating IFNAR signaling activity. Synthetic IFNARs in which the extracellular domains of IFNAR1 and IFNAR2 are replaced with nanobodies had near-native type I IFN signaling, whereas the homomeric variant of IFNAR2 initiated much weaker signaling, despite harboring docking sites for JAKs and STATs. Cells with JAK1 and TYK2 knockout (KO) showed residual signaling, suggesting partial complementation by the remaining JAKs, particularly when they were overexpressed. Live-cell micropatterning experiments confirmed the promiscuous binding of JAK1, JAK2, and TYK2 to IFNAR1 and IFNAR2, and their recruitment correlated with their relative cellular abundances. However, each JAK had a different efficacy in inducing cross-phosphorylation and downstream signaling. JAK binding was also promiscuous for other cytokine receptors, including IFN-L1, IL-10Rβ, TPOR, and GHR, but not for EPOR, which activated different downstream signaling pathways. These findings suggest that competitive binding of JAKs to cytokine receptors together with the varying absolute and relative abundances of the JAKs in different cell types can account for the cell type-dependent signaling pleiotropy of cytokine receptors.

IFN Receptor 2 Regulates TNF-α-Mediated Damaging Inflammation during Aspergillus Pulmonary Infection

The increased incidence of invasive pulmonary aspergillosis, caused by Aspergillus fumigatus, occurring in patients infected with severe influenza or SARS-CoV-2, suggests that antiviral immune responses create an environment permissive to fungal infection. Our recent evidence suggests that absence of the type I IFN receptor 2 subunit (IFNAR2) of the heterodimeric IFNAR1/2 receptor is allowing for this permissive immune environment of the lung through regulation of damage responses. Because damage is associated with poor outcome to invasive pulmonary aspergillosis, this suggested that IFNAR2 may be involved in A. fumigatus susceptibility. In this study, we determined that absence of IFNAR2 resulted in increased inflammation, morbidity, and damage in the lungs in response to A. fumigatus challenge, whereas absence of IFNAR1 did not. Although the Ifnar2-/- mice had increased morbidity, we found that the Ifnar2-/- mice cleared more conidia compared with both wild-type and Ifnar1-/- mice. However, this early clearance did not prevent invasive disease from developing in the Ifnar2-/- mice as infection progressed. Importantly, by altering the inflamed environment of the Ifnar2-/- mice early during A. fumigatus infection, by neutralizing TNF-α, we were able to reduce the morbidity and fungal clearance in these mice back to wild-type levels. Together, our results establish a distinct role for IFNAR2 in regulating host damage responses to A. fumigatus and contributing to an A. fumigatus-permissive environment through regulation of inflammation. Specifically, our data reveal a role for IFNAR2 in regulating TNF-α-mediated damage and morbidity during A. fumigatus infection.

pK205R targets the proximal element of IFN-I signaling pathway to assist African swine fever virus to escape host innate immunity at the early stage of infection

African swine fever virus (ASFV) is a nuclear cytoplasmic large DNA virus (NCLDV) that causes devastating hemorrhagic diseases in domestic pigs and wild boars, seriously threatening the development of the global pig industry. IFN-I plays an important role in the body's antiviral response. Similar to other DNA viruses, ASFV has evolved a variety of immune escape strategies to antagonize IFN-I signaling and maintain its proliferation. In this study, we showed that the ASFV early protein pK205R strongly inhibited interferon-stimulated genes (ISGs) as well as the promoter activity of IFN-stimulated regulatory elements (ISREs). Mechanistically, pK205R interacted with the intracellular domains of IFNAR1 and IFNAR2, thereby inhibiting the interaction of IFNAR1/2 with JAK1 and TYK2 and hindering the phosphorylation and nuclear translocation of STATs. Subsequently, we generated a recombinant strain of the ASFV-pK205R point mutation, ASFV-pK205R7PM. Notably, we detected higher levels of ISGs in porcine alveolar macrophages (PAMs) than in the parental strain during the early stages of ASFV-pK205R7PM infection. Moreover, ASFV-pK205R7PM attenuated the inhibitory effect on IFN-I signaling. In conclusion, we identified a new ASFV immunosuppressive protein that increases our understanding of ASFV immune escape mechanisms.

M2 Macrophage Exosomes Reverse Cardiac Functional Decline in Mice with Diet-Induced Myocardial Infarction by Suppressing Type 1 Interferon Signaling in Myeloid Cells

Effective treatment strategies to alleviate heart failure that develops as a consequence of myocardial infarction (MI) remain an unmet need in cardiovascular medicine. In this study, we uncovered that exosomes produced by human THP-1 macrophages cultured with the cytokine IL-4 (THP1-IL4-exo), reverse cardiac functional decline in mice that develop MI as a consequence of diet-induced occlusive coronary atherosclerosis. Therapeutic benefits of THP1-IL4-exo stem from their ability to reprogram circulating Ly-6Chi monocytes into an M2-like phenotype and suppress Type 1 Interferon signaling in myeloid cells within the bone marrow, the circulation, and cardiac tissue. Collectively, these benefits suppress myelopoiesis, myeloid cell recruitment to cardiac tissue, and preserve populations of resident cardiac macrophages that together mitigate cardiac inflammation, adverse ventricular remodeling, and heart failure. Our findings introduce THP1-IL4-exo, one form of M2-macrophage exosomes, as novel therapeutics to preserve cardiac function subsequent to MI.

Research progress on interferon and cellular senescence

Since the 12 major signs of aging were revealed in 2023, people's interpretation of aging will go further, which is of great significance for understanding the occurrence, development, and intervention in the aging process. As one of the 12 major signs of aging, cellular senescence refers to the process in which the proliferation and differentiation ability of cells decrease under stress stimulation or over time, often manifested as changes in cell morphology, cell cycle arrest, and decreased metabolic function. Interferon (IFN), as a secreted ligand for specific cell surface receptors, can trigger the transcription of interferon-stimulated genes (ISGs) and play an important role in cellular senescence. In addition, IFN serves as an important component of SASP, and the activation of the IFN signaling pathway has been shown to contribute to cell apoptosis and senescence. It is expected to delay cellular senescence by linking IFN with cellular senescence and studying the effects of IFN on cellular senescence and its mechanism. This article provides a review of the research on the relationship between IFN and cellular senescence by consulting relevant literature.

Development of a highly sensitive platform for protein-protein interaction detection and regulation of T cell function

We developed a highly sensitive assay for detecting protein-protein interaction using chimeric receptors comprising two molecules of interest in the extracellular domain and interferon alpha and beta receptor subunit 1 or 2 (IFNAR1/2) in the intracellular domain. This intracellular IFNAR1/2 reconstitution system (IFNARRS) proved markedly more sensitive than the NanoBiT system, currently considered one of the best detection systems for protein interaction. Employing chimeric receptors with extracellular domains from the IFNγ or IL-2 receptor and the intracellular domains of IFNAR1/2, the IFNARRS system effectively identifies low IFNγ or IL-2 levels. Cells stably expressing these chimeric receptors responded to IFNγ secreted by activated T cells following various stimuli, including a specific peptide-antigen. The activation signals were further enhanced by the expression of relevant genes, such as costimulators, via IFN-stimulated response elements in the promoters. Besides IFNγ or IL-2, the IFNARRS system demonstrated the capability to detect other cytokines by using the corresponding extracellular domains from these target cytokine receptors.

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.

Interferons and interferon-related pathways in heart disease

Interferons (IFNs) and IFN-related pathways play key roles in the defence against microbial infection. However, these processes may also be activated during the pathogenesis of non-infectious diseases, where they may contribute to organ injury, or function in a compensatory manner. In this review, we explore the roles of IFNs and IFN-related pathways in heart disease. We consider the cardiac effects of type I IFNs and IFN-stimulated genes (ISGs); the emerging role of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway; the seemingly paradoxical effects of the type II IFN, IFN-γ; and the varied actions of the interferon regulatory factor (IRF) family of transcription factors. Recombinant IFNs and small molecule inhibitors of mediators of IFN receptor signaling are already employed in the clinic for the treatment of some autoimmune diseases, infections, and cancers. There has also been renewed interest in IFNs and IFN-related pathways because of their involvement in SARS-CoV-2 infection, and because of the relatively recent emergence of cGAS-STING as a pattern recognition receptor-activated pathway. Whether these advances will ultimately result in improvements in the care of those experiencing heart disease remains to be determined.

Type I IFN in Glomerular Disease: Scarring beyond the STING

The field of nephrology has recently directed a considerable amount of attention towards the stimulator of interferon genes (STING) molecule since it appears to be a potent driver of chronic kidney disease (CKD). STING and its activator, the cyclic GMP-AMP synthase (cGAS), along with intracellular RIG-like receptors (RLRs) and toll-like receptors (TLRs), are potent inducers of type I interferon (IFN-I) expression. These cytokines have been long recognized as part of the mechanism used by the innate immune system to battle viral infections; however, their involvement in sterile inflammation remains unclear. Mounting evidence pointing to the involvement of the IFN-I pathway in sterile kidney inflammation provides potential insights into the complex interplay between the innate immune system and damage to the most sensitive segment of the nephron, the glomerulus. The STING pathway is often cited as one cause of renal disease not attributed to viral infections. Instead, this pathway can recognize and signal in response to host-derived nucleic acids, which are also recognized by RLRs and TLRs. It is still unclear, however, whether the development of renal diseases depends on subsequent IFN-I induction or other processes involved. This review aims to explore the main endogenous inducers of IFN-I in glomerular cells, to discuss what effects autocrine and paracrine signaling have on IFN-I induction, and to identify the pathways that are implicated in the development of glomerular damage.

LINE-1: an emerging initiator of cGAS-STING signalling and inflammation that is dysregulated in disease

The cGAS-STING (cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING)) axis integrates DNA damage and cellular stress with type I interferon (IFN) signalling to facilitate transcriptional changes underlying inflammatory stress responses. The cGAS-STING pathway responds to cytosolic DNA in the form of double-stranded DNA, micronuclei, and long interspersed nuclear element 1 (L1) retroelements. L1 retroelements are a class of self-propagating non-long terminal repeat transposons that have remained highly active in mammalian genomes. L1 retroelements are emerging as important inducers of cGAS-STING and IFN signalling, which are often dysregulated in several diseases, including cancer. A key repressor of cGAS-STING and L1 activity is the exonuclease three prime repair exonuclease 1 (TREX1), and loss of TREX1 promotes the accumulation of L1. In addition, L1 dysregulation is a common theme among diseases with chronic induction of type I IFN signalling through cGAS-STING, such as Aicardi-Goutières syndrome, Fanconi anemia, and dermatomyositis. Although TREX1 is highly conserved in tetrapod species, other suppressor proteins exist that inhibit L1 retrotransposition. These suppressor genes when mutated are often associated with diseases characterized by unchecked inflammation that is associated with high cGAS-STING activity and elevated levels of L1 expression. In this review, we discuss these interconnected pathways of L1 suppression and their role in the regulation of cGAS-STING and inflammation in disease.

Structure-function of type I and III interferons

Type I and type III interferons (IFNs) are major components in activating the innate immune response. Common to both are two distinct receptor chains (IFNAR1/IFNAR2 and IFNLR1/IL10R2), which form ternary complexes upon binding their respective ligands. This results in close proximity of the intracellularly associated kinases JAK1 and TYK2, which cross phosphorylate each other, the associated receptor chains, and signal transducer and activator of transcriptions, with the latter activating IFN-stimulated genes. While there are clear similarities in the biological responses toward type I and type III IFNs, differences have been found in their tropism, tuning of activity, and induction of the immune response. Here, we focus on how these differences are embedded in the structure/function relations of these two systems in light of the recent progress that provides in-depth information on the structural assembly of these receptors and their functional implications and how these differ between the mouse and human systems.

GSTM2 alleviates heart failure by inhibiting DNA damage in cardiomyocytes

BACKGROUND

Heart failure (HF) seriously threatens human health worldwide. However, the pathological mechanisms underlying HF are still not fully clear.

RESULTS

In this study, we performed proteomics and transcriptomics analyses on samples from human HF patients and healthy donors to obtain an overview of the detailed changes in protein and mRNA expression that occur during HF. We found substantial differences in protein expression changes between the atria and ventricles of myocardial tissues from patients with HF. Interestingly, the metabolic state of ventricular tissues was altered in HF samples, and inflammatory pathways were activated in atrial tissues. Through analysis of differentially expressed genes in HF samples, we found that several glutathione S-transferase (GST) family members, especially glutathione S-transferase M2-2 (GSTM2), were decreased in all the ventricular samples. Furthermore, GSTM2 overexpression effectively relieved the progression of cardiac hypertrophy in a transverse aortic constriction (TAC) surgery-induced HF mouse model. Moreover, we found that GSTM2 attenuated DNA damage and extrachromosomal circular DNA (eccDNA) production in cardiomyocytes, thereby ameliorating interferon-I-stimulated macrophage inflammation in heart tissues.

CONCLUSIONS

Our study establishes a proteomic and transcriptomic map of human HF tissues, highlights the functional importance of GSTM2 in HF progression, and provides a novel therapeutic target for HF.

Membrane-proximal motifs encode differences in signaling strength between type I and III interferon receptors

Interferons (IFNs) play crucial roles in antiviral defenses. Despite using the same Janus-activated kinase (JAK)-signal transducer and activator of transcription (STAT) signaling cascade, type I and III IFN receptors differ in the magnitude and dynamics of their signaling in terms of STAT phosphorylation, gene transcription, and antiviral responses. These differences are not due to ligand-binding affinity and receptor abundance. Here, we investigated the ability of the intracellular domains (ICDs) of IFN receptors to differentiate between type I and III IFN signaling. We engineered synthetic, heterodimeric type I and III IFN receptors that were stably expressed at similar amounts in human cells and responded to a common ligand. We found that our synthetic type I IFN receptors stimulated STAT phosphorylation and gene expression to greater extents than did the corresponding type III IFN receptors. Furthermore, we identified short "box motifs" within ICDs that bind to JAK1 that were sufficient to encode differences between the type I and III IFN receptors. Together, our results indicate that specific regions within the ICDs of IFN receptor subunits encode different downstream signaling strengths that enable type I and III IFN receptors to produce distinct signaling outcomes.

Regulation of human interferon signaling by transposon exonization

Innate immune signaling is essential for clearing pathogens and damaged cells, and must be tightly regulated to avoid excessive inflammation or autoimmunity. Here, we found that the alternative splicing of exons derived from transposable elements is a key mechanism controlling immune signaling in human cells. By analyzing long-read transcriptome datasets, we identified numerous transposon exonization events predicted to generate functional protein variants of immune genes, including the type I interferon receptor IFNAR2. We demonstrated that the transposon-derived isoform of IFNAR2 is more highly expressed than the canonical isoform in almost all tissues, and functions as a decoy receptor that potently inhibits interferon signaling including in cells infected with SARS-CoV-2. Our findings uncover a primate-specific axis controlling interferon signaling and show how a transposon exonization event can be co-opted for immune regulation.

Interferon alpha and beta receptor 1 knockout in human embryonic kidney 293 cells enhances the production efficiency of proteins or adenoviral vectors related to type I interferons

Human embryonic kidney (HEK) 293 cells are widely used in protein and viral vector production owing to their high transfection efficiency, rapid growth, and suspension growth capability. Given their antiviral, anticancer, and immune-enhancing effects, type I interferons (IFNs) have been used to prevent and treat human and animal diseases. However, the binding of type I IFNs to the IFN-α and-β receptor (IFNAR) stimulates the expression of IFN-stimulated genes (ISGs). This phenomenon induces an antiviral state and promotes apoptosis in cells, thereby impeding protein or viral vector production. In this study, we generated an IFNAR subtype 1 knockout (KO) HEK 293 suspension (IFNAR-KO) cell line by using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 nuclease (Cas9) technology. Upon treatment with human IFN-α, the IFNAR-KO cells showed a constant expression of ISGs, including 2'-5'-oligoadenylate synthetase 1 (OAS1), myxovirus resistance 1 (Mx1), protein kinase RNA-activated (PKR), and IFN-induced transmembrane protein 1 (IFITM1), when compared with the wild-type HEK 293 (WT) cells, wherein the ISGs were significantly upregulated. As a result, the titer of recombinant adenovirus expressing porcine IFN-α was significantly higher in the IFNAR-KO cells than in the WT cells. Furthermore, the IFNAR-KO cells continuously produced higher amounts of IFN-α protein than the WT cells. Thus, the CRISPR-Cas9-mediated IFNAR1 KO cell line can improve the production efficiency of proteins or viral vectors related to IFNs. The novel cell line may be used for producing vaccines and elucidating the type I IFN signaling pathway in cells.

Type I Interferonopathy due to a Homozygous Loss-of-Inhibitory Function Mutation in STAT2

PURPOSE

STAT2 is both an effector and negative regulator of type I interferon (IFN-I) signalling. We describe the characterization of a novel homozygous missense STAT2 substitution in a patient with a type I interferonopathy.

METHODS

Whole-genome sequencing (WGS) was used to identify the genetic basis of disease in a patient with features of enhanced IFN-I signalling. After stable lentiviral reconstitution of STAT2-null human fibrosarcoma U6A cells with STAT2 wild type or p.(A219V), we performed quantitative polymerase chain reaction, western blotting, immunofluorescence, and co-immunoprecipitation to functionally characterize the p.(A219V) variant.

RESULTS

WGS identified a rare homozygous single nucleotide transition in STAT2 (c.656C > T), resulting in a p.(A219V) substitution, in a patient displaying developmental delay, intracranial calcification, and up-regulation of interferon-stimulated gene (ISG) expression in blood. In vitro studies revealed that the STAT2 p.(A219V) variant retained the ability to transduce an IFN-I stimulus. Notably, STAT2 p.(A219V) failed to support receptor desensitization, resulting in sustained STAT2 phosphorylation and ISG up-regulation. Mechanistically, STAT2 p.(A219V) showed defective binding to ubiquitin specific protease 18 (USP18), providing a possible explanation for the chronic IFN-I pathway activation seen in the patient.

CONCLUSION

Our data indicate an impaired negative regulatory role of STAT2 p.(A219V) in IFN-I signalling and that mutations in STAT2 resulting in a type I interferonopathy state are not limited to the previously reported R148 residue. Indeed, structural modelling highlights at least 3 further residues critical to mediating a STAT2-USP18 interaction, in which mutations might be expected to result in defective negative feedback regulation of IFN-I signalling.

Natural Killer Cell Derived Microvesicles Affect the Function of Trophoblast Cells

The interaction of natural killer (NK) and trophoblast cells underlies the formation of immune tolerance in the mother-fetus system and the maintenance of the physiological course of pregnancy. In addition, NK cells affect the function of trophoblast cells, interacting with them via the receptor apparatus and through the production of cytokines. Microvesicles (MVs) derived from NK cells are able to change the function of target cells. However, in the overall pattern of interactions between NK cells and trophoblasts, the possibility that both can transmit signals to each other via MVs has not been taken into account. Therefore, the aim of this study was to assess the effect of NK cell-derived MVs on the phenotype, proliferation, and migration of trophoblast cells and their expression of intracellular messengers. We carried out assays for the detection of content transferred from MV to trophoblasts. We found that NK cell-derived MVs did not affect the expression of CD54, CD105, CD126, CD130, CD181, CD119, and CD120a receptors in trophoblast cells or lead to the appearance of CD45 and CD56 receptors in the trophoblast membrane. Further, the MVs reduced the proliferation but increased the migration of trophoblasts with no changes to their viability. Incubation of trophoblast cells in the presence of MVs resulted in the activation of STAT3 via pSTAT3(Ser727) but not via pSTAT3(Tyr705). The treatment of trophoblasts with MVs did not result in the phosphorylation of STAT1 and ERK1/2. The obtained data indicate that NK cell-derived MVs influence the function of trophoblast cells, which is accompanied by the activation of STAT3 signaling.

MicroRNAs and Drug Resistance in Non-Small Cell Lung Cancer: Where Are We Now and Where Are We Going

Lung cancer is the leading cause of cancer-related mortality in the world. The development of drug resistance represents a major challenge for the clinical management of patients. In the last years, microRNAs have emerged as critical modulators of anticancer therapy response. Here, we make a critical appraisal of the literature available on the role of miRNAs in the regulation of drug resistance in non-small cell lung cancer (NSCLC). We performed a comprehensive annotation of miRNAs expression profiles in chemoresistant versus sensitive NSCLC, of the drug resistance mechanisms tuned up by miRNAs, and of the relative experimental evidence in support of these. Furthermore, we described the pros and cons of experimental approaches used to investigate miRNAs in the context of therapeutic resistance, to highlight potential limitations which should be overcome to translate experimental evidence into practice ultimately improving NSCLC therapy.

Functional molecular expression of nature killer cells correlated to HBsAg clearance in HBeAg-positive chronic hepatitis B patients during PEG-IFN α-2a therapy

OBJECTIVE

To explore whether the frequencies and functional molecules expression of Natural Killer cells (NK cells) are related to hepatitis B surface antigen (HBsAg) disappearance in hepatitis B e envelope antigen (HBeAg)-positive patients with chronic hepatitis B (CHB) throughout peginterferon alpha-2a (PEG-IFN α-2a) treatment.

METHODS

In this prospective research, HBeAg-positive patients with CHB received PEG-IFN α-2a treatment, completing 4-year follow-up. After PEG-IFN α-2a treatment, undetectable HBV DNA, HBsAg loss, and HBeAg disappearance were defined as functional cure. Proportions of NK, CD56dim, CD56bright, NKp46+, NKp46dim, NKp46high, and interferon alpha receptor 2 (IFNAR2)+ NK cells, and the mean fluorescence intensity (MFI) of NK cell surface receptors IFNAR2 and NKp46 were detected.

RESULTS

66 patients were enrolled into the study in which 17 patients obtained functional cure. At baseline, hepatitis B virus desoxyribose nucleic acid (HBV DNA) titer in patients with functional cure was remarkably lower than that in Non-functional cure group. Compared with baseline, HBV DNA levels, HBsAg levels, and HBeAg levels significantly declined at week 12 and 24 of therapy in patients with functional cure. At baseline, the negative correlation between CD56bright NK% and HBV DNA and the negative correlation between CD56dim NK% and HBV DNA was showed; CD56bright NK% and IFNAR2 MFI in patients with functional cure were remarkably higher than those in patients without functional cure. After therapy, CD56bright NK% and NKp46high NK% in patients with functional cure were higher than those in patients without functional cure. In Functional cure group, after 24 weeks of treatment NK%, CD56bright NK%, IFNAR2 MFI weakly increased, and NKp46high NK% and NKp46 MFI significantly increased, meanwhile, CD56dim NK% and NKp46dim NK% decreased. Only NKp46 MFI increased after therapy in patients without functional cure.

CONCLUSION

The lower HBV DNA load and the higher CD56bright NK% before therapy, and the higher the post-treatment CD56bright NK%, IFNAR2 MFI, NKp46high NK%, the easier to achieve functional cure.

Defining the Role of Monocytes in Sjögren's Syndrome

Sjögren's syndrome is one of the most prevalent autoimmune diseases after rheumatoid arthritis, with a preference for middle age, and is characterised by exocrine glandular involvement leading to xerostomia and xerophthalmia. It can have systemic implications with vascular, neurological, renal, and pulmonary involvement, and in some cases, it may evolve to non-Hodgkin's lymphoma. For a long time, B- and T-lymphocytes have been the focus of research and have been considered key players in Sjögren's syndrome pathogenesis and evolution. With the development of new technologies, including omics, more insights have been found on the different signalling pathways that lead to inflammation and activation of the immune system. New evidence indicates that a third actor linking innate and adaptive immunity plays a leading role in the Sjögren's syndrome play: the monocyte. This review summarises the recent insights from transcriptomic, proteomic, and epigenetic studies that help us to understand more about the Sjögren's syndrome pathophysiology and redefine the involvement of monocytes in this disease.

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.

Asynchronous excitatory neuron development in an isogenic cortical spheroid model of Down syndrome

The intellectual disability (ID) in Down syndrome (DS) is thought to result from a variety of developmental deficits such as alterations in neural progenitor division, neurogenesis, gliogenesis, cortical architecture, and reduced cortical volume. However, the molecular processes underlying these neurodevelopmental changes are still elusive, preventing an understanding of the mechanistic basis of ID in DS. In this study, we used a pair of isogenic (trisomic and euploid) induced pluripotent stem cell (iPSC) lines to generate cortical spheroids (CS) that model the impact of trisomy 21 on brain development. Cortical spheroids contain neurons, astrocytes, and oligodendrocytes and they are widely used to approximate early neurodevelopment. Using single cell RNA sequencing (scRNA-seq), we uncovered cell type-specific transcriptomic changes in the trisomic CS. In particular, we found that excitatory neuron populations were most affected and that a specific population of cells with a transcriptomic profile resembling layer IV cortical neurons displayed the most profound divergence in developmental trajectory between trisomic and euploid genotypes. We also identified candidate genes potentially driving the developmental asynchrony between trisomic and euploid excitatory neurons. Direct comparison between the current isogenic CS scRNA-seq data and previously published datasets revealed several recurring differentially expressed genes between DS and control samples. Altogether, our study highlights the power and importance of cell type-specific analyses within a defined genetic background, coupled with broader examination of mixed samples, to comprehensively evaluate cellular phenotypes in the context of DS.

Initial activation of STAT2 induced by IAV infection is critical for innate antiviral immunity

STAT2 is an important transcription factor activated by interferons (IFNs) upon viral infection and plays a key role in antiviral responses. Interestingly, here we found that phosphorylation of STAT2 could be induced by several viruses at early infection stage, including influenza A virus (IAV), and such initial activation of STAT2 was independent of type I IFNs and JAK kinases. Furthermore, it was observed that the early activation of STAT2 during viral infection was mainly regulated by the RIG-I/MAVS-dependent pathway. Disruption of STAT2 phosphorylation at Tyr690 restrained antiviral response, as silencing STAT2 or blocking STAT2 Y690 phosphorylation suppressed the expression of several interferon-stimulated genes (ISGs), thereby facilitating viral replication. In vitro experiments using overexpression system or kinase inhibitors showed that several kinases including MAPK12 and Syk were involved in regulation of the early phosphorylation of STAT2 triggered by IAV infection. Moreover, when MAPK12 kinase was inhibited, expression of several ISGs was clearly decreased in cells infected with IAV at the early infection stage. Accordingly, inhibition of MAPK12 accelerated the replication of influenza virus in host. These results provide a better understanding of how initial activation of STAT2 and the early antiviral responses are induced by the viral infection.

Synthetic mimetics assigned a major role to IFNAR2 in type I interferon signaling

Type I interferons (IFNs) are potent inhibitors of viral replication. Here, we reformatted the natural murine and human type I interferon-α/β receptors IFNAR1 and IFNAR2 into fully synthetic biological switches. The transmembrane and intracellular domains of natural IFNAR1 and IFNAR2 were conserved, whereas the extracellular domains were exchanged by nanobodies directed against the fluorescent proteins Green fluorescent protein (GFP) and mCherry. Using this approach, multimeric single-binding GFP-mCherry ligands induced synthetic IFNAR1/IFNAR2 receptor complexes and initiated STAT1/2 mediated signal transduction via Jak1 and Tyk2. Homodimeric GFP and mCherry ligands showed that IFNAR2 but not IFNAR1 homodimers were sufficient to induce STAT1/2 signaling. Transcriptome analysis revealed that synthetic murine type I IFN signaling was highly comparable to IFNα4 signaling. Moreover, replication of vesicular stomatitis virus (VSV) in a cell culture-based viral infection model using MC57 cells was significantly inhibited after stimulation with synthetic ligands. Using intracellular deletion variants and point mutations, Y510 and Y335 in murine IFNAR2 were verified as unique phosphorylation sites for STAT1/2 activation, whereas the other tyrosine residues in IFNAR1 and IFNAR2 were not involved in STAT1/2 phosphorylation. Comparative analysis of synthetic human IFNARs supports this finding. In summary, our data showed that synthetic type I IFN signal transduction is originating from IFNAR2 rather than IFNAR1.

DDX5/METTL3-METTL14/YTHDF2 Axis Regulates Replication of Influenza A Virus

DEAD-box helicase 5 (DDX5), a member of the DEAD/H-box helicases, is known to participate in all aspects of RNA metabolism. However, its regulatory effect in antiviral innate immunity during replication of influenza virus remains unclear. Herein, we found that human DDX5 promotes replication of influenza virus in A549 cells. Moreover, our results further revealed that DDX5 relies on its N terminus to interact with the nucleoprotein (NP) of influenza virus, which is independent of RNA. Of course, we also observed colocalization of DDX5 with NP in the context of transfection or infection. However, influenza virus infection had no significant effect on the protein expression and nucleocytoplasmic distribution of DDX5. Importantly, we found that DDX5 suppresses antiviral innate immunity induced by influenza virus infection. Mechanistically, DDX5 downregulated the mRNA levels of interferon beta (IFN-β), interleukin 6 (IL-6), and DHX58 via the METTL3-METTL14/YTHDF2 axis. We revealed that DDX5 bound antiviral transcripts and regulated immune responses through YTHDF2-dependent mRNA decay. Taken together, our data demonstrate that the DDX5/METTL3-METTL14/YTHDF2 axis regulates the replication of influenza A virus. IMPORTANCE The replication and transcription of influenza virus depends on the participation of many host factors in cells. Exploring the relationship between viruses and host factors will help us fully understand the characteristics and pathogenic mechanisms of influenza viruses. In this study, we showed that DDX5 interacted with the NP of influenza virus. We demonstrated that DDX5 downregulated the expression of IFN-β and IL-6 and the transcription of antiviral genes downstream from IFN-β in influenza virus-infected A549 cells. Additionally, DDX5 downregulated the mRNA levels of antiviral transcripts via the METTL3-METTL14/YTHDF2 axis. Our findings provide a novel perspective to understand the mechanism by which DDX5 regulates antiviral immunity.

Gelatin Stabilizes Nebulized Proteins in Pulmonary Drug Delivery against COVID-19

Delivering medication to the lungs via nebulization of pharmaceuticals is a noninvasive and efficient therapy route, particularly for respiratory diseases. The recent worldwide severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) pandemic urges the development of such therapies as an effective alternative to vaccines. The main difficulties in using inhalation therapy are the development of effective medicine and methods to stabilize the biological molecules and transfer them to the lungs efficiently following nebulization. We have developed a high-affinity angiotensin-converting enzyme 2 (ACE2) receptor-binding domain (RBD-62) that can be used as a medication to inhibit infection with SARS-CoV-2 and its variants. In this study, we established a nebulization protocol for drug delivery by inhalation using two commercial vibrating mesh (VM) nebulizers (Aerogen Solo and PARI eFlow) that generate similar mist size distribution in a size range that allows efficient deposition in the small respiratory airway. In a series of experiments, we show the high activity of RBD-62, interferon-α2 (IFN-α2), and other proteins following nebulization. The addition of gelatin significantly stabilizes the proteins and enhances the fractions of active proteins after nebulization, minimizing the medication dosage. Furthermore, hamster inhalation experiments verified the feasibility of the protocol in pulmonary drug delivery. In short, the gelatin-modified RBD-62 formulation in coordination with VM nebulizer can be used as a therapy to cure SARS-CoV-2.

A Tug of War: Pseudorabies Virus and Host Antiviral Innate Immunity

The non-specific innate immunity can initiate host antiviral innate immune responses within minutes to hours after the invasion of pathogenic microorganisms. Therefore, the natural immune response is the first line of defense for the host to resist the invaders, including viruses, bacteria, fungi. Host pattern recognition receptors (PRRs) in the infected cells or bystander cells recognize pathogen-associated molecular patterns (PAMPs) of invading pathogens and initiate a series of signal cascades, resulting in the expression of type I interferons (IFN-I) and inflammatory cytokines to antagonize the infection of microorganisms. In contrast, the invading pathogens take a variety of mechanisms to inhibit the induction of IFN-I production from avoiding being cleared. Pseudorabies virus (PRV) belongs to the family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus. PRV is the causative agent of Aujeszky’s disease (AD, pseudorabies). Although the natural host of PRV is swine, it can infect a wide variety of mammals, such as cattle, sheep, cats, and dogs. The disease is usually fatal to these hosts. PRV mainly infects the peripheral nervous system (PNS) in swine. For other species, PRV mainly invades the PNS first and then progresses to the central nervous system (CNS), which leads to acute death of the host with serious clinical and neurological symptoms. In recent years, new PRV variant strains have appeared in some areas, and sporadic cases of PRV infection in humans have also been reported, suggesting that PRV is still an important emerging and re-emerging infectious disease. This review summarizes the strategies of PRV evading host innate immunity and new targets for inhibition of PRV replication, which will provide more information for the development of effective inactivated vaccines and drugs for PRV.

A Simplified and Robust Activation Procedure of Glass Surfaces for Printing Proteins and Subcellular Micropatterning Experiments

Depositing biomolecule micropatterns on solid substrates via microcontact printing (µCP) usually requires complex chemical substrate modifications to initially create reactive surface groups. Here, we present a simplified activation procedure for untreated solid substrates based on a commercial polymer metal ion coating (AnteoBindTM Biosensor reagent) that allows for direct µCP and the strong attachment of proteins via avidity binding. In proof-of-concept experiments, we identified the optimum working concentrations of the surface coating, characterized the specificity of protein binding and demonstrated the suitability of this approach by subcellular micropatterning experiments in living cells. Altogether, this method represents a significant enhancement and simplification of existing µCP procedures and further increases the accessibility of protein micropatterning for cell biological research questions.

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.