IFNs Signaling Research Articles

Gene Signature of Regulatory T Cells Isolated from Children with Selective IgA Deficiency and Common Variable Immunodeficiency.

Selective IgA deficiency (SIgAD) is the most common form and common variable immunodeficiency (CVID) is the most symptomatic form of predominant antibody deficiency. Despite differences in the clinical picture, a similar genetic background is suggested. A common feature of both disorders is the occurrence of autoimmune conditions. Regulatory T cells (Tregs) are the major immune cell type that maintains autoimmune tolerance. As the different types of abnormalities of Treg cells have been associated with autoimmune disorders in primary immunodeficiency (PID) patients, in our study we aimed to analyze the gene expression profiles of Treg cells in CVID and SIgAD patients compared to age-matched healthy controls. The transcriptome-wide gene profiling was performed by microarray technology. As a result, we analyzed and visualized gene expression patterns of isolated population of Treg cells. We showed the differences at the gene level between patients with and without autoimmunizations. Our findings suggest that the gene signatures of Treg cells isolated from SIgAD and CVID patients differ from age-matched healthy controls and from each other, presenting transcriptional profiles enriched in innate immune or Th response, respectively. The occurrence of autoimmunity in both types of PID is associated with down-regulation of class I IFNs signaling pathways. In summary, our findings improve our understanding of Treg dysfunctions in patients with common PIDs and associated autoimmunity.

Mice with type I interferon signaling deficiency are prone to epilepsy upon HSV-1 infection

Viral encephalitis continues to be a significant public health concern. In our previous study, we discovered a lower expression of antiviral factors, such as IFN-β, STING and IFI16, in the brain tissues of patients with Rasmussen's encephalitis (RE), a rare chronic neurological disorder often occurred in children, characterized by unihemispheric brain atrophy. Furthermore, a higher cumulative viral score of human herpes viruses (HHVs) was also found to have a significant positive correlation with the unihemispheric atrophy in RE. Type I IFNs (IFN-I) signaling is essential for innate anti-infection response by binding to IFN-α/β receptor (IFNAR). In this study, we infected WT mice and IFNAR-deficient A6 mice with herpes simplex virus 1 (HSV-1) via periocular injection to investigate the relationship between IFN-I signaling and HHVs-induced brain lesions. While all mice exhibited typical viral encephalitis lesions in their brains, HSV-induced epilepsy was only observed in A6 mice. The gene expression matrix, functional enrichment analysis and protein-protein interaction network revealed four gene models that were positively related with HSV-induced epilepsy. Additionally, ten key genes with the highest scores were identified. Taken together, these findings indicate that intact IFN-I signaling can effectively limit HHVs induced neural symptoms and brain lesions, thereby confirming the positive correlation between IFN-I signaling repression and brain atrophy in RE and other HHVs encephalitis.

An Oil-Based Adjuvant Improves Immune Responses Induced by Canine Adenovirus-Vectored Vaccine in Mice.

There is a significant need for highly effective vaccines against emerging and common veterinary infectious diseases. Canine adenovirus type 2 (CAV2) vectors allow rapid development of multiple vaccines and have demonstrated their potential in animal models. In this study, we compared the immunogenicity of a non-replicating CAV2 vector encoding the rabies virus glycoprotein with and without MontanideTM ISA 201 VG, an oil-based adjuvant. All vaccinated mice rapidly achieved rabies seroconversion, which was associated with complete vaccine protection. The adjuvant increased rabies antibody titers without any significant effect on the anti-CAV2 serological responses. An RT2 Profiler™ PCR array was conducted to identify host antiviral genes modulated in the blood samples 24 h after vaccination. Functional analysis of differentially expressed genes revealed the up-regulation of the RIG-I, TLRs, NLRs, and IFNs signaling pathways. These results demonstrate that a water-in-oil-in-water adjuvant can shape the immune responses to an antigen encoded by an adenovirus, thereby enhancing the protection conferred by live recombinant vaccines. The characterization of early vaccine responses provides a better understanding of the mechanisms underlying the efficacy of CAV2-vectored vaccines.

Molecular insight, expression profile and subcellular localization of two STAT family members, STAT1a and STAT2, from Japanese eel, Anguilla japonica.

Signal transducer and activator of transcription 1 (STAT1) and STAT2 are critical components of type I and type II IFNs signaling. To date, seven STAT family proteins have been identified from mammals. However, the information on STAT genes in teleost fish is still limited. In the present study, two STAT family genes (STAT1a and STAT2) were identified from Japanese eel, Anguilla japonica and designated as AjSTAT1a and AjSTAT2. The open reading frames of AjSTAT1a and AjSTAT2 are 2244bp and 2421bp, encoding for polypeptides of 747 aa and 806 aa, respectively. Both AjSTAT1a and AjSTAT2 contain the conserved domains of STAT proteins. Phylogenetic analysis was performed based on the STATs protein sequences, and showed that AjSTAT1a and AjSTAT2 shared the closest relationship with Oncorhynchus mykiss. Quantitative real-time PCR analysis revealed that AjSTAT1a and AjSTAT2 were expressed in most examined tissues, with the highest expression both in blood. Significantly up-regulated transcripts of AjSTAT1a and AjSTAT2 were detected in response to poly I:C stimulation, and Edwardsiella tarda induced increase in the expression of AjSTAT1a and AjSTAT2 genes. Subcellular localization analysis showed that in both IFNγ-stimulated and unstimulated EPC cells AjSTAT1a and AjSTAT2 were mainly distributed in the cytoplasm, but few AjSTAT1a was distributed in the nucleus. All these results suggested that AjSTAT1a and AjSTAT2 may be critical for regulating the host innate immune defense against pathogens invasion.

Ubiquitin specific protease 5 negatively regulates the IFNs-mediated antiviral activity via targeting SMURF1

Type I interferons are broadly used for antiviral therapy in clinical. However, the IFNs-mediated antiviral efficacy is commonly restricted by negative regulators. Here, we show that the ubiquitin-specific protease 5 (USP5) inhibits the IFNs-induced p-STAT1 activation (phosphorylation at tyrosine site of STAT1) and its downstream antiviral genes expression. We clarify that USP5 physically interacts with SMURF1 (Smad ubiquitination regulating factor 1) and IFNs signaling regulates the interaction and turnover of both proteins. USP5 enhances the stability and turnover of SMURF1 via decreasing its polyubiquitin expression level, which caused STAT1 to decrease. Importantly, USP5 is also involved in the SMURF1-mediated antiviral response, and its small-molecule inhibitor PYR41 remarkably enhances the IFNs antiviral efficacy. These findings reveal a previously unrecognized function of the USP5 and USP5-SMURF1 axis in regulating the IFNs-mediated antiviral activity.

Type1 Interferons Potential Initiating Factors Linking Skin Wounds With Psoriasis Pathogenesis.

Psoriasis is a chronic autoimmune skin disease that can often be triggered upon skin injury, known as Koebner phenomenon. Type 1 interferons (IFNα and IFNβ), key cytokines that activate autoimmunity during viral infection, have been suggested to play an indispensable role in initiating psoriasis during skin injury. Type 1 IFN-inducible gene signature has been identified as one of the major upregulated gene signatures in psoriatic skin. Type 1 IFNs treatments often directly induce or exacerbate psoriasis, whereas blocking type 1 IFNs signaling pathway in animal models effectively inhibits the development of T cell-mediated skin inflammation and psoriasis-like inflammatory diseases. Epidermal keratinocytes (KCs) occupy the outermost position in the skin and are the first responder to skin injury. Skin injury rapidly induces IFNβ from KCs and IFNα from dermal plasmacytoid dendritic cells (pDCs) through distinct mechanisms. Host antimicrobial peptide LL37 potentiates double-stranded RNA (dsRNA) immune pathways in keratinocytes and single-stranded RNA or DNA pathways in pDCs, leading to production of distinct type 1 IFN genes. IFNβ from KC promotes dendritic cell maturation and the subsequent T cell proliferation, contributing to autoimmune activation during skin injury and psoriasis pathogenesis. Accumulating evidences have indicated an important role of this dsRNA immune pathway in psoriasis pathogenesis. Together, this review describes how skin injury induces type 1 IFNs from skin cells and how this may initiate autoimmune cascades that trigger psoriasis. Targeting keratinocytes or type 1 IFNs in combination with T cell therapy may result in more sustainable effect to treat auto-inflammatory skin diseases such as psoriasis.

Teleost-specific TLR25 identified from Schizothorax prenanti may recognize bacterial/viral components and activate NF-κB and type I IFNs signaling pathways

TLR25 is a new member of TLR1 family that is only identified in teleosts, but its function in immune response is still unclear. In current study, the coding sequence (CDS) of TLR25 was cloned from Schizothorax prenanti (named spTLR25), and spTLR25 is 2454 bp in length and coding a protein of 817 aa. The spTLR25 contains a signal peptide, twenty leucine-rich repeat (LRR) domains, a LRR C-terminal (LRRCT) motif, a transmembrane region and a Toll/IL-1 receptor (TIR) domain. Phylogenetic analysis indicates that spTLR25 has the closest relationship with Cyprinus carpio (C. carpio) TLR25-2. The 3D structure of spTLR25 exhibits 5 α-helices and 3 β-sheets in the TIR domain, and 8 α-helices and 6 β-sheets in the LRR domains. The spTLR25 is mainly expressed in immune-related tissues and peripheral blood leukocytes (PBL). Furthermore, the expression levels of spTLR25 were upregulated in spleen, head kidney and liver while S. prenanti was challenged with LPS or Aeromonas hydrophila (Ah), and the upregulation was also detected in head kidney leukocytes (HKL) after LPS and Poly (I:C) stimulation. The luciferase reporter assay demonstrated that NF-κB and type I IFNs signaling pathways can be activated by spTLR25, and this process may involve in the cascade amplification of TLR25-MyD88 signaling. In addition, the co-localization analysis showed that spTLR25 localizes to intracellular region. Taken together, our results reveal that teleost-specific TLR25 may be a multifunctional receptor for recognizing both LPS and Poly (I:C) and may activate NF-κB and type I IFNs signaling pathways.

Antibody-dependent enhancement of dengue virus infection inhibits RLR-mediated Type-I IFN-independent signalling through upregulation of cellular autophagy.

Antibody dependent enhancement (ADE) of dengue virus (DENV) infection is identified as the main risk factor of severe Dengue diseases. Through opsonization by subneutralizing or non-neutralizing antibodies, DENV infection suppresses innate cell immunity to facilitate viral replication. However, it is largely unknown whether suppression of type-I IFN is necessary for a successful ADE infection. Here, we report that both DENV and DENV-ADE infection induce an early ISG (NOS2) expression through RLR-MAVS signalling axis independent of the IFNs signaling. Besides, DENV-ADE suppress this early antiviral response through increased autophagy formation rather than induction of IL-10 secretion. The early induced autophagic proteins ATG5-ATG12 participate in suppression of MAVS mediated ISGs induction. Our findings suggest a mechanism for DENV to evade the early antiviral response before IFN signalling activation. Altogether, these results add knowledge about the complexity of ADE infection and contribute further to research on therapeutic strategies.

Identification of amino-acid residues in the V protein of peste des petits ruminants essential for interference and suppression of STAT-mediated interferon signaling

Peste des petits ruminants virus (PPRV) causes a fatal disease in small ruminants. V protein of PPRV plays a pivotal role in interfering with host innate immunity by blocking IFNs signaling through interacting with STAT1 and STAT2. In the present study, the results demonstrated that PPRV V protein blocks IFN actions in a dose dependent manner and restrains the translocation of STAT1/2 proteins. We speculate that the translocation inhibition might be caused by the interfering of the downstream of STAT protein. Mutagenesis defines that Cys cluster and Trp motif of PPRV V protein are essential for STAT-mediated IFN signaling. These findings give a new sight for the further studies to understand the delicate mechanism of PPRV to escape the IFN signaling.

Functional limitations of plasmacytoid dendritic cells limit type I interferon, T cell responses and virus control in early life.

Infant mortality from viral infection remains a major global health concern: viruses causing acute infections in immunologically mature hosts often follow a more severe course in early life, with prolonged or persistent viral replication. Similarly, the WE strain of lymphocytic choriomeningitis virus (LCMV-WE) causes acute self-limiting infection in adult mice but follows a protracted course in infant animals, in which LCMV-specific CD8+ T cells fail to expand and control infection. By disrupting type I IFNs signaling in adult mice or providing IFN-α supplementation to infant mice, we show here that the impaired early life T cell responses and viral control result from limited early type I IFN responses. We postulated that plasmacytoid dendritic cells (pDC), which have been identified as one major source of immediate-early IFN-I, may not exert adult-like function in vivo in the early life microenvironment. We tested this hypothesis by studying pDC functions in vivo during LCMV infection and identified a coordinated downregulation of infant pDC maturation, activation and function: despite an adult-like in vitro activation capacity of infant pDCs, the expression of the E2-2 pDC master regulator (and of critical downstream antiviral genes such as MyD88, TLR7/TLR9, NF-κB, IRF7 and IRF8) is downregulated in vivo at baseline and during LCMV infection. A similar pattern was observed in response to ssRNA polyU, a model ligand of the TLR7 viral sensor. This suggests that the limited T cell-mediated defense against early life viral infections is largely attributable to / regulated by infant pDC responses and provides incentives for novel strategies to supplement or stimulate immediate-early IFN-α responses.

Type I IFNs signaling and apoptosis resistance in glioblastoma cells

Deletion of type I IFN genes and resistance to apoptosis induced by type I IFNs are common in glioblastoma. Here we have investigated the importance of the constitutive weak IFN-signaling in the apoptotic response to IFN-α in glioblastoma cells. U87MG cells hold a deletion of type I IFN genes, whereas in T98G cells the spontaneous IFN signaling is intact. In response to IFN-α U87MG cells produce much less TRAIL, while other IFN-inducible genes were efficiently up-regulated. Alterations in TRAIL promoter sequence and activity were not observed. DNA methylation can influence TRAIL transcription but without overt differences between the two cell lines. We also discovered that TRAIL mRNA stability is influenced by IFN-α, but again no differences can be appreciated between the two cell lines. By silencing IFNAR1 we provide evidences that the spontaneous IFN signaling loop is required to sustain elevated levels of TRAIL expression, possibly through the regulation of IRF-1. Despite the presence/absence of the constitutive IFN signaling, both cell lines were resistant to IFN-α induced apoptosis. Targeting the deisgylase USP18 can overcome resistance to IFN-induced apoptosis only in T98G cells. Alterations in elements of the extrinsic apoptotic pathway, such as Bid and c-FLIP contribute to apoptotic resistance of U87MG cells. Down-regulation of USP18 expression together with the induction of ER-stress efficiently restored apoptosis in U87MG cells. Finally, we demonstrated that the BH3-only protein Noxa provides an important contribution in the apoptotic response to ER-stress in USP18 silenced cells.