Project description:Successful host defense against pathogens requires innate immune recognition of the correct pathogen associated molecular patterns (PAMPs) by pathogen recognition receptors (PRRs) to trigger the appropriate gene program tailored to the pathogen. While many PRR pathways have been shown to contribute to the innate immune response to specific pathogens, the relative importance of each pathway for the complete transcriptional program elicited has not been examined in detail. Herein, we used RNA-sequencing with wildtype and mutant macrophages to delineate the innate immune pathways responsible for the early transcriptional response to Staphylococcus aureus, a ubiquitous microorganism that can activate a wide variety of PRRs. Unexpectedly, only two PRR pathways – the Toll-like receptor (TLR) and Stimulator of Interferon Gene (STING) pathways - were identified as dominant regulators of approximately 95% of the genes that were potently induced within the first four hours of macrophage infection with live S. aureus. TLR signaling predominantly activated an inflammatory program, STING signaling activated an antiviral/type I interferon response, and both pathways contributed to a program linking innate and adaptive immunity. Only a small number of genes were induced in the absence of TLR or STING signaling, and these genes possessed a strong hypoxia signature. STING pathway activation required live S. aureus and was largely dependent on the DNA sensor cyclic guanosine-adenosine synthase (cGAS) recognition of S. aureus DNA. Interestingly, using a cutaneous infection model, we found that the TLR and STING pathways played opposite roles in host defense to S. aureus, with TLR signaling being required for protective interleukin (IL)-1 and neutrophil recruitment and STING signaling having an opposite effect. These results provide novel insights into the complex interplay of innate immune signaling pathways triggered byS. aureus and uncover opposing roles of TLR and STING in cutaneous host defense to S. aureus.
Project description:STING plays a key role in detecting cytosolic DNA and induces type I interferon responses for host defense against pathogens. Although T cells highly express STING, its physiological role remains unknown. In this study, we show that costimulation of T cells via TCR and STING ligand induce type I IFN responses like innate immune cells.
Project description:Gene expression analysis of dsDNA90 stimulated human telomerase fibroblasts (hTERT-BJ1) after STING siRNA treatment. Genes whose expression that are affected by cytosolic DNA in a STING dependent manner will be identified and signaling pathways regulated by STING will be elucidated. hTERT-BJ1 cells were transfected with non-specific or STING siRNA for 72 hours followed by dsDNA90 stimulation for 3 hours. Total RNA was extracted for array analysis.
Project description:Innate immune PRRs sense nucleic acids from microbes and orchestrate cytokine production to resolve infection. Inappropriate recognition of host nucleic acids also results in autoimmune disease. Here we utilize a model of inflammation resulting from accrual of self DNA (DNase II-/- Ifnar-/-) to understand the role of PRR sensing pathways in arthritis and autoantibody production. Using mice deficient in DNase II/Ifnar together with deficiency in either STING or AIM2 (TKO), we reveal central roles for the STING and AIM2 pathway in arthritis. AIM2 TKO mice show limited inflammasome activation and, like STING TKO mice, have reduced inflammation in joints. Surprisingly, autoantibody production is maintained in AIM2 and STING TKO mice, while DNase II-/- Ifnar-/- mice also deficient in Unc93b, a chaperone required for TLR7/9 endosomal localization, fail to produce autoantibodies to nucleic acids. Collectively, these data support distinct roles for cytosolic and endosomal nucleic acid sensing pathways in disease manifestations.
Project description:Gene expression analysis of wild type, STING knock-out and STAT1 knock-out Mouse Embryonic Fibroblasts (MEFs) stimulated with 90-mer dsDNA or 90-mer ssDNA. Genes whose expression that are affected by cytosolic DNA in a STING dependent manner will be identified and signaling pathways regulated by STING will be elucidated. Primary MEFs were mock treated or transfected with dsDNA90 or ssDNA90 for 3 hours. Total RNA was then extracted for array analysis.
Project description:The transcription factor Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is activated by the metabolite itaconate during metabolic reprogramming. Activated Nrf2 then dampens the release of pro-inflammatory cytokines and type I IFNs in response to toll-like receptor stimulation. If and how Nrf2 affects cytosolic antiviral sensing and whether this occurs during metabolic reprogramming is currently not known. Here, we show that Nrf2 is a negative regulator of the adaptor molecule STimulator of INterferon Genes (STING), which signals downstream of the cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS). The regulation of STING by Nrf2 was inducible by the metabolite itaconate, specific to human cells, and sufficient to decrease the responsiveness to STING agonists and to increase the susceptibility to infection with DNA viruses. Mechanistically, Nrf2 regulated STING expression post-transcriptionally by increasing STING mRNA stability. Lastly, treatment with itaconate or with the chemical Nrf2 inducer sulforaphane repressed STING expression and the release of type I IFNs in cells from patients with the STING dependent interferonopathy SAVI. With this report we identify Nrf2 as an important regulator of cGAS-STING signaling pathway and link metabolic reprogramming to control of cytosolic DNA sensing.
Project description:Gene expression analysis of dsDNA90 stimulated human telomerase fibroblasts (hTERT-BJ1) after STING siRNA treatment. Genes whose expression that are affected by cytosolic DNA in a STING dependent manner will be identified and signaling pathways regulated by STING will be elucidated.
Project description:STING molecule has been reported to be important adaptor molecule for cytosolic DNA sensing. We investigated gene expression by cytosolic DNA stimulation using bone marrow derived dendritic cells. We comparared gene expression profile between WT and STING knock out BMDCs after cytosolic DNA stimulation. We generated BMDCs by culturing in the presence of GM-CSF. BMDCs were stimulated by purified tumor-cell derived DNA using lipofectamine. After 7 hrs incubation, total RNA was isolated using Rneasy kit (Qiagen) and microarray was performed at genomic core facility in university of Chicago
Project description:Gene expression analysis of wild type, STING knock-out and STAT1 knock-out Mouse Embryonic Fibroblasts (MEFs) stimulated with 90-mer dsDNA or 90-mer ssDNA. Genes whose expression that are affected by cytosolic DNA in a STING dependent manner will be identified and signaling pathways regulated by STING will be elucidated.
Project description:We perform RNA-seq in CH12F3 and Lig4-/- CH12F3 cells. The results show the deficiency of Lig4 triggers RIG-I-like receptor, NOD-like receptor, IL-17 signaling, Cytosolic DNA-sensing pathway, and Toll-like receptor signaling pathways. As these pathways play impotant roles in immune resposne, the RNA-seq results suggest Lig4 may regulate the immune repsonse in CH12F3 cells.