Project description:To determine the role of Sting pathway involving in the pathogenesis of SLE in a lupus mouse model of Fcgr2b-deficient mice. To identify mechanisms of the Sting signaling that contributes to SLE development
Project description:Inflammatory diseases such as Aicardi-Goutieres Syndrome (AGS) and severe systemic lupus erythematosus (SLE) are generally lethal disorders that have been traced to defects in the exonuclease Trex1 (DNAseIII). Mice lacking Trex1 similarly die at an early age through comparable symptoms, including inflammatory myocarditis, through chronic activation of the STING (stimulator of interferon genes) pathway. Here we demonstrate that phagocytes rather than myocytes are predominantly responsible for causing inflammation, an outcome that could be alleviated following adoptive transfer of normal bone marrow into Trex1-/- mice. Trex1-/- macrophages did not exhibit significant augmented ability to produce pro-inflammatory cytokines compared to normal macrophages following exposure to STING-dependent activators, but rather appeared chronically stimulated by genomic DNA. These results shed molecular insight into inflammation and provide concepts for the design of new therapies. Total RNA obtained from wild type (WT), Trex1 deficient (TKO), STING deficient (SKO), or Trex1 and STING double deficient (STKO) mouse Heart
Project description:Chronic stimulation of innate immune pathways by microbial agents or damaged tissue is known to promote inflammation-driven tumorigenesis by unclarified mechanisms1-3. Here we demonstrate that mutagenic 7,12-dimethylbenz(a)anthracene (DMBA), etoposide or cisplatin induces nuclear DNA leakage into the cytosol to intrinsically activate STING (Stimulator of Interferon Genes) dependent cytokine production. Inflammatory cytokine levels were subsequently augmented in a STING-dependent extrinsic manner by infiltrating phagocytes purging dying cells. Consequently, STING-/- mice, or wild type mice adoptively transferred with STING-/- bone marrow, were almost completely resistant to DMBA-induced skin carcinogenesis compared to their wild type counterparts. Our data emphasizes, for the first time, a role for STING in the induction of cancer, sheds significant insight into the causes of inflammation-driven carcinogenesis, and may provide therapeutic strategies to help prevent malignant disease Total RNA obtained from wild type murine embryonic fibroblasts (WT MEFs), STING deficient MEFs (SKO), Trex1 deficient MEFs (TKO), and both STING and Trex1 deficient MEFs (STKO) treated with DMBA and examined cytokine production by these cells.
Project description:Inflammatory diseases such as Aicardi-Goutieres Syndrome (AGS) and severe systemic lupus erythematosus (SLE) are generally lethal disorders that have been traced to defects in the exonuclease Trex1 (DNAseIII). Mice lacking Trex1 similarly die at an early age through comparable symptoms, including inflammatory myocarditis, through chronic activation of the STING (stimulator of interferon genes) pathway. Here we demonstrate that phagocytes rather than myocytes are predominantly responsible for causing inflammation, an outcome that could be alleviated following adoptive transfer of normal bone marrow into Trex1-/- mice. Trex1-/- macrophages did not exhibit significant augmented ability to produce pro-inflammatory cytokines compared to normal macrophages following exposure to STING-dependent activators, but rather appeared chronically stimulated by genomic DNA. These results shed molecular insight into inflammation and provide concepts for the design of new therapies. Total RNA obtained from wild type murine embryonic fibroblasts (WT MEFs), Trex1 deficient MEFs (TKO) or STING and Trex1 double deficient MEFs (STKO) transfected with or without double strand DNA 90 (ISD) and examined cytokine production by these cells.
Project description:Chronic stimulation of innate immune pathways by microbial agents or damaged tissue is known to promote inflammation-driven tumorigenesis by unclarified mechanisms1-3. Here we demonstrate that mutagenic 7,12-dimethylbenz(a)anthracene (DMBA), etoposide or cisplatin induces nuclear DNA leakage into the cytosol to intrinsically activate STING (Stimulator of Interferon Genes) dependent cytokine production. Inflammatory cytokine levels were subsequently augmented in a STING-dependent extrinsic manner by infiltrating phagocytes purging dying cells. Consequently, STING-/- mice, or wild type mice adoptively transferred with STING-/- bone marrow, were almost completely resistant to DMBA-induced skin carcinogenesis compared to their wild type counterparts. Our data emphasizes, for the first time, a role for STING in the induction of cancer, sheds significant insight into the causes of inflammation-driven carcinogenesis, and may provide therapeutic strategies to help prevent malignant disease Total RNA obtained from DMBA or acetone treated wild type (WT) or STING deficient (SKO) mouse skin or skin tumor was examined for gene expression.
Project description:STING gain-of-function (GOF) mutations lead to T cell lymphopenia, in the context of severe combined immunodeficiency (SCID) for STING GOF V154M mice. This T cell lymphopenia, which is of central origin, has been described as type I IFN independent and associated with dysfunctions of the rare mature T cells found in the periphery. To better describe the biological mechanisms of these dysfunctions, we performed a transcriptomic analysis by RNA-seq on sorted splenic CD4+ and CD8+ mature T cells from STING GOF mice. We highlighted an unexpected T cell exhaustion phenotype that could partly explain their dysfunctions. Acquired very early in life, but only once the peripheral environment is reached, the phenotype appeared to depend neither on type I IFNs, nor on the intrinsic activation of STING in T or stromal cells. Mechanistically, the few mature T cells reaching the periphery seem to be rapidly impacted by the lymphopenic environment through increased antigenic and IL-7 stimulations that could lead to their exhaustion. By using STING GOF long term-hematopoietic stem cells (LT-HSC) transplantations with supportive wild-type bone marrow (BM) cells, we prevented the T cell exhaustion of STING GOF T cells in the resulting non lymphopenic context. With the support of lymphopenic RAG1 hypomorphic mice developing the phenotype, our data uncover a lymphopenia-mediated T cell exhaustion mechanism in STING GOF mice, for which a synergistic effect of the mutation is also envisaged.
Project description:The innate immune system is equipped with multiple receptors to detect microbial nucleic acids and induce type I interferon (IFN) to restrict viral replication. When dysregulated these receptor pathways induce inflammation in response to host nucleic acids and promote development and persistence of autoimmune diseases like Systemic Lupus Erythematosus (SLE). IFN production is regulated by the Interferon Regulatory Factor (IRF) transcription factor family of proteins that function downstream of several innate immune receptors such as Toll-like receptors (TLRs) and Stimulator of Interferon Genes (STING). Although both TLRs and STING activate the same downstream molecules, the pathway by which TLRs and STING activate IFN response are thought to be independent. Here we show that STING plays a previously undescribed role in human TLR8 signaling. Stimulation with the TLR8 ligands induced IFN secretion in primary human monocytes, and inhibition of STING reduced IFN secretion from primary monocytes from 8 healthy donors. We demonstrate that TLR8-induced IRF activity was reduced by STING inhibitors. Moreover, TLR8-induced IRF activity was blocked by inhibition or loss of IKKε, but not TBK1. Bulk RNA transcriptomic analysis supported a model where TLR8 induces transcriptional responses associated with SLE that can be downregulated by inhibition of STING. These data demonstrate that STING is required for full TLR8-to-IRF signaling and provide evidence for a new framework of crosstalk between cytosolic and endosomal innate immune receptors, which could be leveraged to treat IFN driven autoimmune diseases.
Project description:Stimulator of Interferon Genes (STING) is a key mediator of type-I interferon (IFN-I) signaling in response to a variety of stimuli, but the contribution of STING to homeostatic processes is not fully characterized. Previous studies showed ligand activation of STING limits osteoclast differentiation in vitro through the induction of IFN and IFN-I Interferon Stimulated Genes (ISGs). In a disease model (SAVI) driven by the V154M gain-of-function mutation in STING, fewer osteoclasts form from SAVI precursors in response to RANKL in an IFN-I-dependent manner. Due to the described role of STING-mediated regulation of osteoclastogenesis in activation settings, we sought to determine whether basal STING signaling contributes to bone homeostasis, an unexplored area. Using whole-body and myeloid-specific deficiency, we show that STING signaling prevents trabecular bone loss in mice over time and that myeloid-restricted STING activity is sufficient for this effect. STING-deficient osteoclast precursors differentiate with greater efficiency than wildtypes. RNA sequencing of wildtype and STING-deficient osteoclast precursor cells and differentiating osteoclasts reveals novel clusters of ISGs including a previously undescribed ISG set expressed in RANKL naïve precursors (tonic expression) and downregulated during differentiation. We identify a 50 gene tonic ISG signature that is STING-dependent and shapes osteoclast differentiation. From this list, we identify Interferon Stimulated Gene 15 (ISG15) as a tonic STING-regulated ISG that limits osteoclast formation. Thus, STING is an important upstream regulator of tonic IFN-I signatures shaping the commitment to osteoclast fates, providing evidence for a nuanced and novel role for this pathway in bone homeostasis.
Project description:Chymotrypsin-like elastase 1 (CELA1) is a serine protease that is neutralized by alpha-1 antitrypsin (AAT) and prevents emphysema in a murine antisense oligonucleotide model of AAT-deficient emphysema. We tested the role of CELA1 in emphysema development in this genetic model of AAT-deficiency following tracheal lipopolysaccharide (LPS), 10 months of cigarette smoke (CS) exposure, aging, and a low-dose tracheal porcine pancreatic elastase (LD-PPE) model we developed. In this last model, we performed proteomic analysis to understand differences in lung protein composition. We were unable to show that AAT-deficient mice developed more emphysema than wild type with escalating doses of LPS.