Defining mechanisms of CD8 T cell exhaustion in T1D

项目总结/摘要 治疗1型糖尿病（T1 D）的关键障碍，1型糖尿病是一种自身免疫性疾病，其中胰岛β细胞是 被免疫细胞破坏的过程，就是理解疾病的异质性。免疫源之一 最近在新近发病的T1 D受试者中发现的异质性是部分耗尽的CD 8+细胞的存在， 对抗CD 3疗法具有有益应答的受试者中的T细胞（Long，et.al Science Immunology）。同样地， 疾病进展较慢的受试者具有较高的胰岛特异性CD 8 T细胞频率， 耗尽的特征。然而，T1 D中的潜在衰竭机制尚未得到很好的理解。通过 相反，在慢性病毒环境中，已经确定IL-2/IL-15轴参与分化， 持久性和CD 8耗竭：IL-2可用性增加可阻止分化，而对IL-2/IL-8的应答 持久性需要15。在T1 D中，我们沿着发表了一些开创性的研究， IL-2/IL-15轴与T1 D的关系。在这里，我们发现T1 D受试者的CD 8 T细胞耗竭频率较低， 在CD 8耗竭的细胞中具有较高水平的CD 4 IL-2产生和较低水平的IL-15应答。因此，IL- 与T1 D相关的IL-2/IL-15缺陷为阐明IL-2在CD 8 + T细胞上的作用提供了独特的机会。 疲惫不堪我们假设T1 D患者IL-2/IL-15轴的改变导致了T1 D患者外周血中IL-2/IL-15水平的降低。 分化成胰岛特异性耗尽的CD 8 T细胞和降低的持久性。我们将测试这个 假设在两个重点目标中使用来自已确定的T1 D的精心策划的人类队列的样本， 临床T1 D和健康对照（HC）受试者，以及多维单细胞方法，包括质量 流式细胞术（CyTOF）、RNA-seq和ATAC-seq结合创新的系统免疫学方法。在 目的1，我们建议阐明增加CD 4 IL 2的产生，导致减少耗竭的机制 在疾病的不同阶段。在目标2中，我们将阐明在糖尿病患者中IL-12/IL-15应答降低的机制。 耗尽的CD 8 T细胞导致有限的持久性耗尽。圆满完成这些目标 将1）促进我们对CD 8 T细胞耗竭作为T1 D耐受性未充分研究形式的理解，2） 提高我们对导致T1 D疾病进展的免疫因素的理解，以及3）提供 基金会的发展，旨在促进疲惫的疗法。

PROJECT SUMMARY/ABSTRACT A critical barrier to treating Type 1 Diabetes (T1D), an autoimmune disease in which the islet beta cells are destroyed by immune cells, is understanding the heterogeneity of disease. One source of immune heterogeneity recently identified across recent onset T1D subjects is the presence of partially exhausted CD8 T cells in subjects with beneficial response to anti-CD3 therapy (Long, et.al Science Immunology). Likewise, subjects with slower disease progression have great frequencies of islet-specific CD8 T cells with more features of exhaustion. Yet, the mechanisms underlying exhaustion in T1D are not well understood. By contrast, in chronic viral settings it is well established that the IL-2/IL-15 axis is involved in differentiation and persistence and CD8 exhaustion: increased IL-2 availability prevents differentiation, while response to IL-2/IL- 15 is required for persistence. In T1D, we published seminal studies along with others that link alterations in the IL-2/IL-15 axis with T1D. Here, we find that T1D subjects with lower frequencies of exhausted CD8 T cells have higher levels of CD4 IL-2 production and lower levels of IL-15 response in CD8 exhausted cells. Thus, IL- 2/IL-15 defects associated with T1D present a unique opportunity to elucidate the role of IL-2 on CD8 exhaustion. We hypothesize that alterations in the IL-2/IL-15 axis in T1D lead to decreased differentiation into islet-specific exhausted CD8 T cells and reduced persistence. We will test this hypothesis in two focused aims using samples from well curated human cohorts of established T1D, pre- clinical T1D and healthy control (HC) subjects, and multi-dimensional single cell approaches including mass cytometry (CyTOF), RNA-seq and ATAC-seq combined with innovative systems immunology approaches. In Aim 1, we propose to elucidate mechanisms of increased CD4 IL2 production that lead to reduced exhaustion at different stages of disease. In Aim 2, we will elucidate mechanisms of reduced IL-12/IL-15 response in exhausted CD8 T cells that results in limited persistence of exhaustion. Successful completion of these aims will 1) advance our understanding of CD8 T cell exhaustion as an understudied form of tolerance in T1D, 2) improve our understanding of immune factors contributing to T1D disease progression, and 3) provide the foundation for the development of therapies designed to promote exhaustion.