Project description:Phospholipid scramblase 2 (PLSCR2) plays an negative role in type I IFN responses. PLSCR2 constitutively interacts with STAT3, and PLSCR2 deficiency enhances IFN-I-induced gene expression and antiviral activity in an STAT3-dependent manner. We used microarrays to compare the overall difference of intrinsic and IFN-induced gene expression between wild-type and PLSCR2 deficient cells
Project description:Type-I (e.g. IFN-alpha, IFN-beta) and type-II IFNs (IFN-gamma) have antiviral, antiproliferative, and immunomodulatory properties. Both types of IFN signal through the Jak/STAT pathway to elicit antiviral activity, yet IFN-gamma is thought to do so only through STAT1 homodimers while type-I IFNs activate both STAT1- and STAT2-containing complexes such as ISGF3. Here we show that ISGF3II - composed of phosphorylated STAT1, unphosphorylated STAT2, and IRF9 - also plays a role in IFN-gamma-mediated antiviral activity in humans. Using phosphorylated STAT1 as a marker for IFN signaling, western blot analysis of IFN-alpha2a treated human A549 cells revealed that pSTAT1 (Y701) levels peaked at 1h, decreased by 6h, and remained at low levels for up to 48h. Cells treated with IFN-gamma showed a biphasic pSTAT1 response with an early peak at 1-2h and a second peak at 15-24h. Gene expression microarray following IFN-gamma treatment for 24h indicated an induction of antiviral genes that are induced by ISGF3 and associated with a type-1 IFN response. Induction of these genes by autocrine type-I and type-III IFN signaling was ruled out using neutralizing antibodies to these IFNs in biological assays and by qRT-PCR. Despite the absence of autocrine IFNs, IFN-gamma treatment induced formation of ISGF3II. This novel transcription factor complex binds to ISRE promoter sequences, as shown by ChIP analysis of the PKR promoter. STAT2 and IRF9 knockdown in A549 cells reversed IFN-gamma-mediated ISRE induction and antiviral activity - implicating ISGF3II formation as a significant component of the cellular response and biological activity of IFN-gamma. Two treatments using three biological replicates each were performed using three million A549 cells. Each was seeded overnight in 10mL complete RPMI and treated. Three were treated with alpha-IFN and three treated with gamma-IFN for 24h. Control samples were left untreated.
Project description:Type-I (e.g. IFN-alpha, IFN-beta) and type-II IFNs (IFN-gamma) have antiviral, antiproliferative, and immunomodulatory properties. Both types of IFN signal through the Jak/STAT pathway to elicit antiviral activity, yet IFN-gamma is thought to do so only through STAT1 homodimers while type-I IFNs activate both STAT1- and STAT2-containing complexes such as ISGF3. Here we show that ISGF3II - composed of phosphorylated STAT1, unphosphorylated STAT2, and IRF9 - also plays a role in IFN-gamma-mediated antiviral activity in humans. Using phosphorylated STAT1 as a marker for IFN signaling, western blot analysis of IFN-alpha2a treated human A549 cells revealed that pSTAT1 (Y701) levels peaked at 1h, decreased by 6h, and remained at low levels for up to 48h. Cells treated with IFN-gamma showed a biphasic pSTAT1 response with an early peak at 1-2h and a second peak at 15-24h. Gene expression microarray following IFN-gamma treatment for 24h indicated an induction of antiviral genes that are induced by ISGF3 and associated with a type-1 IFN response. Induction of these genes by autocrine type-I and type-III IFN signaling was ruled out using neutralizing antibodies to these IFNs in biological assays and by qRT-PCR. Despite the absence of autocrine IFNs, IFN-gamma treatment induced formation of ISGF3II. This novel transcription factor complex binds to ISRE promoter sequences, as shown by ChIP analysis of the PKR promoter. STAT2 and IRF9 knockdown in A549 cells reversed IFN-gamma-mediated ISRE induction and antiviral activity - implicating ISGF3II formation as a significant component of the cellular response and biological activity of IFN-gamma.
Project description:This SuperSeries is composed of the following subset Series: GSE36241: Identification of a FOXO3/IRF7 circuit that limits inflammatory sequelae of antiviral responses (ChIP-Seq) GSE37051: Identification of a FOXO3/IRF7 circuit that limits inflammatory sequelae of antiviral responses (expression) Refer to individual Series
Project description:Viruses target mitochondria, critical for antiviral defense and metabolism, to evade immunity. While mitochondrial antiviral-signaling protein (MAVS) is known for its regulation of type I interferon (IFN) signaling, we discover that its overarching primary role is safeguarding mitochondrial integrity against virus- and toxin-induced mitophagy. This function is critical in enacting a potent, IFN/NF-κB-independent antiviral response. Using SARS-CoV-2 (CoV-2) infection model, where disruption of MAVS aggregation and induction of mitophagy were observed, we demonstrate that functional MAVS prevents CoV-2-induced mitophagy and restricts viral replication without engaging type I or III interferon (IFN), and NF-κB pathways. Employing MAVS-knockout and MAVS:IFNAR1 double-knockout cells, and inhibition studies, our results further establish MAVS as a critical protector against virus- and chemical mitotoxin-induced mitophagy. Loss of MAVS results in increased mitochondrial membrane depolarization, reduced oxidative potential, and increased PINK1-dependent mitophagy leading to elevated viral replication-all reversed by MAVS supplementation. The IFN-independent antiviral immunity generated by MAVS-driven mitochondrial safeguarding conferred robust protection against mitophagy-inducing viruses, such as CoV-2 and JEV, but not DENV, which does not trigger mitophagy. By facilitating the mitochondrial integrity, MAVS governs the overall innate antiviral immunity- integrating IFN-dependent and IFN-independent mechanisms- and energy metabolism in the host cells. Thus, the regulation of these central functions makes MAVS a prime target for subverting host defenses and cellular energy homeostasis. These insights underscoring MAVS’s wider role in sustaining mitochondrial homeostasis positions it as a promising target for antiviral strategies.
Project description:Introduction: Thymic Stromal Lymphopoietin (TSLP) is a primarily epithelial-derived cytokine that drives type 2 allergic immune responses. Early life viral respiratory infections elicit high TSLP production, which leads to the development of type 2 inflammation and airway hyperreactivity. The goal of this study was to examine in vivo and in vitro the human airway epithelial responses leading to high TSLP production during viral respiratory infections in early infancy. Methods: A total of 129 infants (<1m – 24m, median age 10m) with severe viral respiratory infections were enrolled for in vivo (n=113), and in vitro studies (n=16). Infants were classified as “high TSLP” or “low TSLP” for values above or below the 50th percentile. High vs. low TSLP groups were compared in terms of type I-III IFN responses and production of chemokines promoting antiviral (CXCL10), neutrophilic (CXCL1, CXCL5, CXCL8), and type 2 responses (CCL11, CCL17, CCL22). Human infant airway epithelial cell (AEC) cultures were used to define the transcriptomic (RNAseq) profile leading to high vs. low TSLP responses in vitro. Results: Infants in the high TSLP group had greater in vivo type III IFN airway production (median type III IFN in high TSLP 183.2 pg/ml vs. 63.4 pg/ml in low TSLP group, p= 0.007) and increased in vitro type I-III IFN AEC responses after stimulation with a viral mimic (poly I:C). Our RNAseq data showed that infants in the high TSLP group had significant baseline upregulation of IFN signature genes (e.g., IFIT2, IFI6, MX1) and pro-inflammatory chemokine genes prior to viral mimic stimulation. Infants in the high TSLP group also showed a baseline AEC pro-inflammatory state characterized by increased production of all the chemokines assayed (e.g., CXCL10, CXCL8) in the absence of viral stimuli. Conclusion: High TSLP responses in the human infant airways are associated with pre-activated airway epithelial IFN antiviral immunity and increased baseline AEC production of pro-inflammatory chemokines. These findings present a new paradigm underlying the high production of TSLP in the human infant airway epithelium and shed light on the pathogenesis of viral respiratory illnesses during early infancy and beyond childhood.
Project description:In acute HIV infection immune activation may provide target cells and drive virus replication, which innate immunity may limit. Thus, the net effects of inflammatory mediators, including type I interferon (IFN-I), are unclear. Here, we block IFN-I signaling during pathogenic acute SIV infection with an IFN-I receptor antagonist. Delayed antiviral gene expression, increased SIV reservoir, increased CD4 T cell depletion and accelerated progression to AIDS and death ensue despite decreased T cell activation. In contrast, IFNα2a treatment initially upregulates antiviral genes and prevents systemic SIV infection after rectal challenge. Antiviral gene expression normalizes, and infection ensues with fewer transmitted/founder variants. Continued IFNα2a treatment causes delayed antiviral gene expression, increased SIV reservoir and increased CCR5+ CD4 T cell loss. Thus, the precise timing of antiviral gene expression has a profound impact on disease course. The benefits of early antiviral activity outweigh the harms of increased immune activation in acute SIV infection. SRA Study accession: SRP034563, BioProject ID:PRJNA231884