Determining the mechanism of IFIH1 disease-associated variants on beta-cell and immune responses in Type 1 diabetes

项目摘要/摘要 1型糖尿病(T1D)是一种多因素自身免疫性疾病，需要遗传易感性 以及引发疾病的环境因素，如病毒感染。一例病毒感染 与T1D高度相关的是柯萨奇B组病毒(CVB)血清型。CVB的感知是 由黑色素瘤分化相关蛋白5(MDA5)介导，MDA5是dsRNA的胞质传感器， 这是由IFIH1基因编码的。刺激MDA5信号通路激活 转录因子irf3和nf-κB p65，它们诱导I型IFN的合成，通过 自分泌信号启动抗病毒转录程序。单核苷酸多态 (SNPs)的IFIH1基因，如rs1990760，这导致了一个非同义突变， 将946位丙氨酸改变为苏氨酸，与T1D风险增加高度相关。 对人外周血单核细胞和小鼠的研究表明，A946T SNP导致A946T单核苷酸多态性增加。 对病毒配体的敏感性，以及随后更强的下游干扰素反应。巨噬细胞有 以前被证明在T1D启动中起着重要作用，然而，β-细胞对 病毒感染也很重要。我们的中心假设是与T1D相关的SNPs导致 加重胰岛滞留巨噬细胞免疫反应和β细胞炎症反应 CVB3感染有助于启动自身免疫。这将用单核细胞进行测试- 衍生的巨噬细胞和树突状细胞以及诱导的多能干细胞 来自健康供者和T1D患者的具有IFIH1基因分型的人胰腺β-细胞 导致T1D易感性和耐药性的SNPs。

Project Summary/Abstract Type 1 diabetes (T1D) is a multifactorial autoimmune disease that requires genetic susceptibility as well as environmental triggers such as viral infections in triggering disease onset. One viral infection that is highly correlated with T1D is the Coxsackievirus B (CVB) serotype. Sensing of CVB is mediated by the melanoma differentiation-associated protein 5 (MDA5), a cytosolic sensor of dsRNA, which is encoded by the IFIH1 gene. Stimulation of the MDA5 signaling pathway activates the transcription factors IRF3 and NF-κB p65, which induce Type I IFNs synthesis, which through autocrine signaling initiate an antiviral transcriptional program. Single nucleotide polymorphisms (SNPs) in the IFIH1 gene such as rs1990760, which results in a non-synonymous mutation that changes alanine at position 946 to a threonine, is highly associated with increased risk for T1D. Studies in human PBMCs and mice have demonstrated that the A946T SNP results in an increased sensitivity to viral ligands and subsequently a stronger downstream IFN response. Macrophages have been shown previously to play an important role in T1D initiation, however, the response of β-cells to viral infection is also important. Our central hypothesis is that T1D-associated SNPs result in an exacerbated islet-resident macrophage immune response and β-cell inflammatory response following CVB3 infection which contributes to the initiation of autoimmunity. This will be tested using monocyte- derived macrophages and dendritic cells and induced pluripotent stem cells engineered to become human pancreatic β-cells from healthy donors and patients with T1D that are genotyped for IFIH1 SNPs that contribute to T1D susceptibility and resistance.