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

项目摘要 1型糖尿病（T1 D）是由产生胰岛素的胰腺β细胞的自身免疫性破坏引起的。 非肥胖型糖尿病（NOD）小鼠发生自发性T1 D，并已被广泛用于研究糖尿病性T1 D。 这种自身免疫性疾病的遗传和致病机制。最近，白细胞介素的致糖尿病作用 （IL）-21已经出现，并且与正常小鼠相比，NOD小鼠表达更高水平的这种细胞因子。 对T1 D耐药菌株。IL-21由CD 4 T细胞产生，其对T1 D的贡献部分是通过 支持直接杀死胰腺β细胞的致糖尿病CD 8 T细胞的存活和功能的能力。 NOD小鼠在胰岛中具有IL-21+ CD 4 T细胞的年龄依赖性积累。重要的是，NOD小鼠 遗传上导致的IL-21缺陷完全抵抗胰岛炎和糖尿病的发展。 有趣的是，NOD胰岛IL-21+ CD 4 T细胞具有不同于典型Th 17和Tfh的独特表型， CD 4 T细胞效应子亚群被称为IL-21的主要生产者。与IL-10的致糖尿病功能一致， 21在NOD小鼠中，现有证据也支持其在人类T1 D中的作用。显著更高水平的 在β细胞自身免疫受试者中发现循环IL-21+ CD 4 T细胞和IL-21蛋白， 健康对照IL-21+ CD 4 T细胞如何在NOD和T1 D进展期间出现和积累 小鼠和人类在很大程度上仍然未知，因此值得进一步研究。50多个位点 已通过全基因组关联研究（GWAS）与人类T1 D相关。最大的风险之一 基因是PTPN 22。人PTPN 22风险等位基因调节T细胞功能并促进T1 D， 引入NOD小鼠。值得注意的是，非自身免疫易感性C57 BL/6小鼠品系上的PTPN 22缺陷 背景已经与较高频率的Tfh CD 4 T细胞及其增强的Tfh CD 4 T细胞产生相关。 IL-21。解决PTPN 22是否通过调节分化调节糖尿病发展 NOD小鼠中胰岛IL-21+ CD 4 T细胞的状态将提供对T1 D遗传控制的更好理解。 我们的假设是，β细胞自身反应性CD 4 T细胞产生IL-21的能力代表了一种独特的免疫调节机制。 这种分化状态由Ptpn 22变体调节。我们提出以下目标来检验这一点 假说.目标1。通过以下方法确定表达IL-21的胰岛浸润性CD 4 T细胞的分化状态： 使用单细胞RNA测序鉴定它们的转录网络。目标二。以确定影响 Ptpn 22变体对胰岛浸润性IL-21表达性CD 4 T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.