Project description:Gain-of-function mutations in STING cause STING-associated vasculopathy with onset in infancy (SAVI) characterized by early-onset systemic inflammation, skin vasculopathy, and interstitial lung disease. Here, we report and characterize a novel STING variant (F269S) identified in a SAVI patient. single-cell transcriptomics of patient bone marrow revealed spontaneous activation of interferon (IFN) and inflammatory pathways across cell types and a striking prevalence of circulating naïve T cells was observed. Inducible STING F269S expression conferred enhanced signaling through ligand-independent translocation of the protein to the Golgi, protecting cells from viral infections but preventing their efficient immune priming. Additionally, endothelial cell activation was promoted and further exacerbated by cytokine secretion by SAVI immune cells, resulting in inflammation and endothelial damage. Our findings identify STING F269S mutation as a novel pathogenic variant causing SAVI, highlight the importance of the crosstalk between endothelial and immune cells in the context of lung disease and contribute to a better understanding of how aberrant STING activation can cause pathology.
Project description:Gain-of-function mutations in STING cause STING-associated vasculopathy with onset in infancy (SAVI) characterized by early-onset systemic inflammation, skin vasculopathy, and interstitial lung disease. Here, we report and characterize a novel STING variant (F269S) identified in a SAVI patient. Single-cell transcriptomics of patient bone marrow revealed spontaneous activation of interferon (IFN) and inflammatory pathways across cell types and a striking prevalence of circulating naïve T cells was observed. Inducible STING F269S expression conferred enhanced signaling through ligand-independent translocation of the protein to the Golgi, protecting cells from viral infections but preventing their efficient immune priming. Additionally, endothelial cell activation was promoted and further exacerbated by cytokine secretion by SAVI immune cells, resulting in inflammation and endothelial damage. Our findings identify STING F269S mutation as a novel pathogenic variant causing SAVI, highlight the importance of the crosstalk between endothelial and immune cells in the context of lung disease, and contribute to a better understanding of how aberrant STING activation can cause pathology.
Project description:Constitutive activation of STING by gain-of-function mutations triggers manifestation of the systemic autoinflammatory disease STING-associated vasculopathy with onset in infancy (SAVI) in humans and in mice. Murine SAVI is characterized by T cell lymphopenia, severe inflammatory interstitial lung disease, neuroinflammation and neurodegeneration with only limited contribution of type I interferon signaling. Here, we show that pharmacologic inhibition of TNF signaling in SAVI mice improved T cell lymphopenia, but had no effect on interstitial lung disease. However, complete blocking of TNF receptor signaling by knocking out TNFR1 and TNFR2 in SAVI mice rescued both, loss of thymocytes as well as interstitial lung disease. Furthermore, chronic STING signaling in lung endothelial cells of diseased mice enhanced transcription of cytokines, chemokines and adhesions proteins resulting in increased transendothelial migration of neutrophils across the endothelial barrier that could be reverted by genetic inactivation of TNFR1 and 2. Thus, our results demonstrate a pivotal role of TNFR-signaling in the development of SAVI-associated lung disease and suggest this pathway as promising target to ameliorate human SAVI
Project description:Gain-of-function mutations in STING1, that codes for the Stimulator of Interferon Gene (STING), result in a severe autoinflammatory disease termed STING-associated vasculopathy with onset in infancy (SAVI). Although elevated type I interferon (IFN) production is thought to be the leading cause of the symptoms observed in patients, STING can induce a set of pathways, and their role in the onset and severity of SAVI remains to be elucidated. To address this point, we compared a single-cell RNA sequencing (scRNA-seq) dataset of peripheral blood mononuclear cells (PBMCs) from SAVI patients to a dataset of healthy PBMCs treated with recombinant IFN-β. We revealed a loss of mucosal associated invariant T cells and CD56bright natural killer cells in SAVI patients, not replicated in IFN-β-treated PBMC. Patient T cells are in an activated state associated with senescence and apoptosis, dependent on type I IFNs. Inferring cell to cell communication, from scRNA-seq predicted monocytes as potential drivers of this T cell phenotype and was supported by plasma cytokines measurement, with high CCL3, CCL4 and IL-6. Furthermore, scRNA-seq clustering identified a patient-specific subset of monocytes, highly inflammatory and expressing a strong integrated stress response (ISR). It also pinpointed to a patient with lower ISR, allowing us to identify a secondary mutation in PERK, that was recently shown to be activated by STING to trigger the ISR. Finally, based on the identification of this patient-specific subset of monocytes and the exploration of IFN-β stimulated PBMCs from healthy donors, we developed a strategy to propose a transcriptomic signature specific of STING activation and independent of type I IFN. Altogether, these results provide a deeper understanding of SAVI at the cellular and molecular levels.
Project description:Gain-of-function mutations in STING1, that codes for the Stimulator of Interferon Gene (STING), result in a severe autoinflammatory disease termed STING-associated vasculopathy with onset in infancy (SAVI). Although elevated type I interferon (IFN) production is thought to be the leading cause of the symptoms observed in patients, STING can induce a set of pathways, and their role in the onset and severity of SAVI remains to be elucidated. To address this point, we compared a single-cell RNA sequencing (scRNA-seq) dataset of peripheral blood mononuclear cells (PBMCs) from SAVI patients to a dataset of healthy PBMCs treated with recombinant IFN-β. We revealed a loss of mucosal associated invariant T cells and CD56bright natural killer cells in SAVI patients, not replicated in IFN-β-treated PBMC. Patient T cells are in an activated state associated with senescence and apoptosis, dependent on type I IFNs. Inferring cell to cell communication, from scRNA-seq predicted monocytes as potential drivers of this T cell phenotype and was supported by plasma cytokines measurement, with high CCL3, CCL4 and IL-6. Furthermore, scRNA-seq clustering identified a patient-specific subset of monocytes, highly inflammatory and expressing a strong integrated stress response (ISR). It also pinpointed to a patient with lower ISR, allowing us to identify a secondary mutation in PERK, that was recently shown to be activated by STING to trigger the ISR. Finally, based on the identification of this patient-specific subset of monocytes and the exploration of IFN-β stimulated PBMCs from healthy donors, we developed a strategy to propose a transcriptomic signature specific of STING activation and independent of type I IFN. Altogether, these results provide a deeper understanding of SAVI at the cellular and molecular levels.
Project description:Pediatric patients with constitutively active mutations in the cytosolic dsDNA sensing adaptor STING develop an autoinflammatory syndrome known as STING Associated Vasculopathy with onset in Infancy (SAVI). SAVI patients have elevated interferon stimulated gene expression and suffer from interstitial lung disease (ILD) with lymphocyte predominate bronchus associated lymphoid tissue (BALT). Mice harboring SAVI mutations (STING V154M or VM) that recapitulate human disease also develop lymphocyte rich BALT formation. Ablation of either T or B lymphocytes prolongs survival of SAVI mice, but lung immune aggregates persist, indicating that T cells and B cells can independently be recruited as BALT. VM T cells produced IFNγ and IFNγR deficiency prolonged the survival of SAVI mice; however, T cell dependent recruitment of infiltrating myeloid cells to the lung was independent of IFNγ. Lethally irradiated VM recipients fully reconstituted with WT BM-derived cells still developed ILD, pointing to a critical role for VM-expressing radioresistant parenchymal and/or stromal cells in the recruitment and activation of pathogenic lymphocytes. We identified lung endothelial cells as radioresistant cells which express STING. Transcriptional analysis of VM endothelial cells revealed upregulation of chemokines, pro-inflammatory cytokines, and genes associated with antigen presentation. Together, our data show that VM-expressing radioresistant cells play a key role in the initiation of lung disease in VM mice and provide new insights for the treatment of SAVI patients, with implications for ILD associated with other connective tissue disorders.
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: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.