Reporting IL-17 in Type 1 Diabetes

描述（由申请人提供）：1型糖尿病（T1D）目前是一种无法治愈的疾病，因为自身免疫反应破坏产生胰岛素的b岛细胞无法控制。自身反应性CD4细胞是T1D的关键协调者。它们不断升级的反应最终逃脱了监管，导致胰腺的急性炎症和糖尿病的发作。虽然产生IFN-g的Th1细胞对疾病发病至关重要，但产生il -17的Th17细胞是否或何时参与T1D尚不清楚。分泌IL-17A和IL-17F的Th17细胞与几种自身免疫性疾病有关。我们的研究表明，IL-17A和IFN-g分泌CD4 T细胞在NOD小鼠的胰岛素期和T1D发病时胰腺浸润中是不同的亚群，而IL-17F未被检测到。此外，血清IL-17A和IFN-g水平升高预示着高血糖的发生。我们现在发现IL-17A+ CD4 T细胞极大地加速了正常（WT） NOD小鼠的糖尿病。根据我们的发现以及在T1D患者中IL-17A+细胞的检测，我们假设Th17细胞是T1D发病的重要贡献者。然而，如果没有额外的工具，就不可能直接解决调节这些细胞反应的机制或它们的效应功能，这些效应功能可能是控制自身免疫反应的目标。我们的目标是在NOD背景下开发一种新的IL-17A报告小鼠，通过谱系追踪来原位分析Th17细胞在T1D进展过程中的发育和反应，在未来的R01资助中，我们计划继续研究Th17细胞在T1D中的调节作用。我们建议使用基于细菌人工染色体（BAC）的基因报告和基因敲入策略来创建小鼠，使其能够识别和分离获得Il17a基因表达的CD4细胞，正如在Il17a位点插入的GFP-Cre融合蛋白的表达所报道的那样。我们将使用双报告策略，将这些动物与Rosa26-YFP NOD小鼠杂交，以不可磨灭地标记具有IL-17A产生历史的细胞。这些小鼠将为明确研究Th17细胞对T1D的贡献以及Th1和Th17细胞之间导致糖尿病发病的潜在功能相互关系提供新的工具。识别Th17细胞发育及其功能变化的能力将有助于设计适当的策略来控制自身侵袭性CD4细胞，并为Th17细胞的生物学提供新的见解。

DESCRIPTION (provided by applicant): Type 1 diabetes (T1D) is currently an incurable disease because the autoimmune response that destroys insulin-producing b islet cells cannot be controlled. Autoreactive CD4 cells are key orchestrators of T1D. Their escalating responses ultimately escape regulation, leading to acute inflammation in the pancreas and diabetes onset. While it is clear that IFN-g producing Th1 cells are essential to disease pathogenesis, whether or when IL-17-producing Th17 cells contribute to T1D is unknown. Th17 cells that secrete IL-17A and to a lesser extent IL-17F have been implicated in several autoimmune diseases. Our studies show that IL-17A- and IFN-g- secreting CD4 T cells are distinct subsets in pancreatic infiltrates during the insulitis phase and at T1D onset in NOD mice, whereas IL-17F is not detected. In addition, elevated serum levels of IL-17A and IFN-g herald the onset of hyperglycemia. We now find that IL-17A+ CD4 T cells greatly accelerate diabetes in normal (WT) NOD mice. On the basis of our findings and the detection of IL-17A+ cells in T1D patients, we hypothesize that Th17 cells are important contributors to the pathogenesis of T1D. However, without additional tools, it will not be possible to directly address mechanisms that regulate the responses of these cells or their effector functions that could be targeted to control the autoimmune response. Our goal is to develop a novel IL-17A reporter mouse on the NOD background that will enable analysis of the development and responses of Th17 cells in situ by lineage tracing during progression to T1D and, in a future R01 grant we plan to pursue studies of the regulation of Th17 cells in T1D. We propose to use bacterial artificial chromosome (BAC)-based gene reporter and gene knockin strategies to create mice that will enable identification and isolation of CD4 cells that acquire Il17a gene expression, as reported by expression of a GFP-Cre fusion protein inserted in the Il17a locus. We will use a double reporter strategy by breeding these animals to Rosa26-YFP NOD mice to indelibly mark cells with a history of IL-17A production. These mice will provide a novel tool to unequivocally study the contributions of Th17 cells to T1D and the potential functional interrelationships between Th1 and Th17 cells that lead to diabetes onset. The ability to identify changes in the development of Th17 cells and their functions will facilitate the design of appropriate strategies to control autoaggressive CD4 cells and provide new insights into the biology of Th17 cells. PUBLIC HEALTH RELEVANCE: It will be crucial to control the autoimmune response to cure T1D; however, tools to identify changes that occur in the CD4 T cells that orchestrate the disease are lacking. We propose to generate a novel reporter mouse using the NOD mouse model of T1D that will permit tracking of a subset known as Th17 cells, whose functions are controversial but implicated in other diseases. This essential tool will greatly improve our understanding of T1D and the potential for targeting the CD4 cell population.