Genetic analysis of islet-infiltrating IL-21-expressing CD4 T cells in type 1 diabetes

项目总结 1型糖尿病(T1D)是由产生胰岛素的胰岛β细胞的自身免疫破坏引起的。 非肥胖糖尿病(NOD)小鼠发展为自发性T1D，并已被广泛用于研究 这种自身免疫性疾病的遗传和致病机制。最近，白介素有促糖尿病作用 (IL)-21已经出现，与NOD小鼠相比，NOD小鼠表达了更高水平的这种细胞因子 对T1D抗性菌株。IL-21是由CD4T细胞产生的，其对T1D的贡献部分是通过其 支持直接杀死胰岛β细胞的糖尿病原性CD8 T细胞的生存和功能的能力。 NOD小鼠胰岛IL-21CD4T细胞随年龄增长而积聚。重要的是，NOD老鼠 基因上呈现的IL-21缺陷是完全抵抗胰腺炎和糖尿病的发展的。 有趣的是，NOD胰岛IL-21CD4T细胞具有不同于典型Th17和Tfh的独特表型 CD4T细胞效应器亚群被称为IL-21的主要产生者。与IL-1的促糖尿病作用一致- 21在NOD小鼠中，现有证据也支持它在人类T1D中的作用。显著更高的 β细胞自身免疫受试者外周血中IL-21CD4T细胞和IL-21蛋白的表达 健康对照组。IL-21 CD4T细胞在T1D进展过程中在两个结节中的产生和积聚 老鼠和人类在很大程度上仍不为人所知，因此值得进一步研究。超过50个基因座 通过全基因组关联研究(GWAS)发现与人类T1D相关。最大的风险之一 基因是PTPN22。人类PTPN22风险等位基因调节T细胞功能并促进T1D 被引入NOD小鼠体内。值得注意的是，非自身免疫倾向的C57BL/6小鼠品系的PTPN22缺乏 背景一直与较高的Tfh CD4T细胞频率和它们增强的 IL-21。PTPN22是否通过调节分化调控糖尿病的发生 NOD小鼠胰岛IL-21CD4T细胞的状态将为更好地了解T1D的基因调控提供依据。 我们的假设是，β细胞自身反应的CD4T细胞产生IL-21的能力代表着一种独特的 受PTPN22变异体调控的分化状态。我们提出以下目标来测试这一点 假设。目的1.确定表达IL-21的胰岛CD4T细胞的分化状态 用单细胞RNA测序鉴定它们的转录网络。目标2.确定以下因素的影响 PTPN22变异体对表达IL-21的胰岛CD4T细胞分化的影响

PROJECT SUMMARY Type 1 diabetes (T1D) is caused by autoimmune destruction of insulin-producing pancreatic beta-cells. Nonobese diabetic (NOD) mice develop spontaneous T1D and have been used extensively to study the genetic and pathogenic mechanisms of this autoimmune disease. Recently, a diabetogenic role of interleukin (IL)-21 has emerged, and higher levels of this cytokine were shown to be expressed by NOD mice compared to the T1D resistant strains. IL-21 is produced by CD4 T cells and its contribution to T1D is in part through its ability to support the survival and function of diabetogenic CD8 T cells that directly kill pancreatic beta-cells. NOD mice have an age dependent accumulation of IL-21+ CD4 T cells in islets. Importantly, NOD mice genetically rendered IL-21-deficient are completely resistant to the development of insulitis and diabetes. Interestingly, NOD islet IL-21+ CD4 T cells have a unique phenotype distinct from that of typical Th17 and Tfh CD4 T cell effector subsets known as the main IL-21 producers. Consistent with a diabetogenic function of IL- 21 in NOD mice, available evidence also supports its role in human T1D. Significantly higher levels of circulating IL-21+ CD4 T cells and IL-21 protein were found in subjects with beta-cell autoimmunity than in healthy controls. How IL-21+ CD4 T cells emerge and accumulate during the progression of T1D in both NOD mice and humans remains largely unknown and therefore deserves further investigation. More than 50 loci have been associated with human T1D by genome wide association studies (GWAS). One of the top risk genes is PTPN22. The human PTPN22 risk allele modulates T cell functions and promotes T1D when introduced into NOD mice. Notably, PTPN22 deficiency on the non-autoimmune prone C57BL/6 mouse strain background has been associated with a higher frequency of Tfh CD4 T cells and their enhanced production of IL-21. Addressing whether PTPN22 regulates diabetes development through modulating the differentiation states of islet IL-21+ CD4 T cells in NOD mice will provide a better understanding of the genetic control of T1D. Our hypothesis is that the ability of beta-cell autoreactive CD4 T cells to produce IL-21 represents a unique differentiation state that is modulated by Ptpn22 variants. We propose the following aims to test this hypothesis. Aim 1. To define the differentiation state of islet-infiltrating IL-21-expressing CD4 T cells by identifying their transcriptional networks using single-cell RNA sequencing. Aim 2. To determine the effects of Ptpn22 variants on the differentiation of islet-infiltrating IL-21-expressing CD4 T cells.