Role of MDA5 responses on islet-resident macrophages in Type 1 diabetes

项目摘要 1型糖尿病（T1 D）是一种自身免疫性疾病，导致胰腺β细胞 由于T细胞产生的促炎细胞因子/趋化因子的产生而引起的破坏 细胞、巨噬细胞和其他免疫细胞。最近的证据表明，柯萨奇病毒 B组（CVB）感染和先天性病毒感受器黑色素瘤分化的增加- 相关蛋白5（MDA 5）应答与人类中的T1 D发展相关。在小鼠中， CVB感染加速T1 D发展，部分原因是MDA 5上调。研究 为了研究MDA 5在T1 D中的作用，我们建立了一种新的NOD小鼠模型，称为NOD.Ifih1Δ Hel 1。 NOD.Ifih1Δ Hel 1小鼠在Ifih 1的解旋酶1结构域中含有突变，该基因编码 MDA5。表达Ifih 1 Δ Hel 1突变的小鼠表现出T1 D发展的延迟，这是由于 减少胰腺内的促炎性巨噬细胞和T细胞反应。但 目前尚不清楚MDA 5生化功能如何改变先天性和适应性免疫细胞， 调节T1 D发作。我将确定MDA 5生化功能如何影响胰岛居民 巨噬细胞（IRMs）的反应，以促进或抑制T1 D的发展。我会决定 如果IRM上的Ifih 1 Δ Hel 1突变影响先天性病原体感知和抗原呈递， 延迟T1 D。为了加深对MDA 5如何调节自身免疫的理解，我将 检测WT和Ifih 1 Δ Hel 1 MDA 5 ATPase活性和dsRNA结合功能。我 假设降低的MDA 5 ATP酶活性可以抑制 胰岛，从而减少炎症、自身反应性T细胞的激活，随后， 延迟T1 D发作。为了检验这一假设，将确定以下独立目标： 确定Ifih 1 Δ Hel 1突变是否损害巨噬细胞病毒感知和抗原呈递。 (ii)确定Ifih 1 Δ Hel 1突变是否导致ATP酶活性和dsRNA结合降低， MDA5。从这些研究中获得的见解将增加我们对 IRM上的MDA 5驱动自身免疫性T1 D和胰腺β细胞破坏。

Project Summary Type 1 diabetes (T1D) is an autoimmune disease resulting in pancreatic β-cell destruction due to the generation of proinflammatory cytokines/chemokines generated by T cells, macrophages, and other immune cells. Recent evidence has revealed that coxsackievirus group B (CVB) infection and an increase in innate viral sensor melanoma differentiation- associated protein 5 (MDA5) responses are correlated to T1D development in humans. In mice, CVB infection accelerates T1D development in part due to MDA5 upregulation. To study the role of MDA5 in T1D, we have generated a novel NOD mouse model called NOD.Ifih1ΔHel1. NOD.Ifih1ΔHel1 mice contain a mutation in the helicase 1 domain of Ifih1, the gene encoding for MDA5. Mice expressing the Ifih1ΔHel1 mutation exhibit a delay in T1D development, due to reduced proinflammatory macrophage and T cell responses within the pancreata. However, it remains unclear how MDA5 biochemical function alters innate and adaptive immune cells to regulate T1D onset. I will determine how MDA5 biochemical function affects islet-resident macrophages (IRMs) responses to either promote or dampen T1D development. I will determine if the Ifih1ΔHel1 mutation on IRMs affects innate pathogen sensing and antigen presentation to delay T1D. To enhance the understanding of how MDA5 can regulate autoimmunity, I will examine the function of WT and Ifih1ΔHel1 MDA5 ATPase activity and dsRNA binding. I hypothesize that reduced MDA5 ATPase activity can dampen IRM responsiveness within the islets, thereby reducing inflammation, activation of autoreactive T cells, and subsequently, delaying T1D onset. To test this hypothesis, the following independent aims will be defined: (i) Determine if the Ifih1ΔHel1 mutation impairs macrophage viral sensing and antigen presentation. (ii) Determine if the Ifih1ΔHel1 mutation results in reduced ATPase activity and dsRNA binding of MDA5. The insights gained from these studies will increase our understanding of the role of MDA5 on IRMs to drive autoimmune T1D and pancreatic β-cells destruction.