Beta-cell self-antigen recognition by diabetogenic CD8 T cells

项目总结 1型糖尿病(T1D)是T细胞介导的胰腺中产生胰岛素的β细胞破坏的结果 小岛。这种“错误”的免疫反应需要自身反应性CD8T细胞，但它们是如何驱动疾病的 定义不明确。在自身反应性T细胞的生命过程中，有两个与疾病密切相关的关键时间点， 也就是说，它们在胸腺中产生，在外周激活。前者未能消除潜在的 致病T细胞，而后者允许它们移动到目标组织并停留在目标组织中以调节损伤。 这两种情况都严格依赖于对β细胞自身抗原的识别。然而，人们对此知之甚少。 导致糖尿病的CD8 T细胞识别β细胞抗原。我们多年来一直在研究T细胞抗原 使用新的超灵敏二维(2D)力方法进行识别，显示出2D TCR亲和力和 与肽的结合寿命：MHC是决定胸腺细胞选择结果的两个主要动力学参数 T细胞效应器功能。目前的项目旨在使用这些2D方法来定义β-β结合动力学。 外周胸腺发育过程中糖尿病CD8 T细胞对细胞抗原的识别 效应器功能与T1D发病机制。我们的初步数据显示，CD8 T细胞与 胸腺细胞选择过程中的β细胞抗原，但在激活时增加结合强度。这种自我的改变-- 反应性由辅受体CD8介导。相反，对于外来抗原，相同的参数没有改变。 承认。这些数据支持我们的核心假设，即在自身免疫性糖尿病中，CD8从根本上改变 通过调节TCR结合动力学来识别自身抗原，从而赋予CD8T细胞 高度的自我反应性，克服自我耐受性来调节β细胞的破坏。我们建议两个 具体目的是检验这一假说。在Aim1中，我们将定义β细胞抗原的2D亲和力和结合寿命 CD8T细胞的识别。我们假设，即使在单个克隆水平上，导致糖尿病的CD8 T细胞也是 在抗原识别方面高度适应，因此它们使用弱结合动力学来存活于中枢和外周 耐受性强，但极大地提高了自我反应性，从而引发疾病。我们将使用一组克隆的 基于NOD小鼠模型T1D的糖尿病TCR细胞克隆的系统研究 糖尿病CD8 T细胞选择和外周血细胞活化过程中的抗原识别 研究β细胞抗原识别的可塑性与自身免疫性糖尿病之间的因果关系。 在AIM2中，我们将阐明β细胞抗原识别的潜在机制。我们假设 糖尿病CD8T细胞识别β细胞抗原的可塑性是由于CD8与MHC的结合动力学所致。 我们将首先确定CD8在整个β细胞抗原识别中的作用。然后我们将测试一种潜艇- CD8糖基化独特模式决定T细胞CD8结合动力学适应性的假说 糖链图谱、表型和单细胞转录分析。

Project summary Type 1 diabetes (T1D) is a result of T-cell mediated destruction of insulin-producing beta-cells in the pancreatic islets. Autoreactive CD8 T cells are required in this “mistaken” immune response but how they drive disease is ill-defined. There are two key time points during the life of autoreactive T cells closely related to disease, namely, their creation in the thymus and activation in the periphery. The former fails to eliminate the potentially pathogenic T cells whereas the latter allows them to travel to and stay in the target tissue to mediate damage. Both events are strictly dependent on recognition of beta-cell self-antigens. However, little is known about how diabetogenic CD8 T cells recognize beta-cell antigens. We have over the years studied T cell antigen recognition using novel ultrasensitive two-dimensional (2D) force-based methods, showing 2D TCR affinity and bond lifetime with peptide:MHC as two main kinetics parameters that dictate thymocyte selection outcome and T cell effector functions. The current project aims to use these 2D methods to define binding kinetics of beta- cell antigen recognition by diabetogenic CD8 T cells in the context of their thymic development, peripheral effector function, and T1D pathogenesis. Our preliminary data show that CD8 T cells form weak bonds with beta-cell antigens during thymocyte selection but increase bond strength upon activation. Such change of self- reactivity is mediated by coreceptor CD8. In contrast, the same parameters did not change for foreign antigen recognition. These data support our central hypothesis that, in autoimmune diabetes, CD8 fundamentally alters self-antigen recognition through modulation of TCR binding kinetics, thereby endowing CD8 T cells with heightened self-reactivity that overcomes self-tolerance to mediate beta-cell destruction. We propose two specific aims to test this hypothesis. In Aim1, we will define 2D affinity and bond lifetime of beta-cell antigen recognition by CD8 T cells. We hypothesize that diabetogenic CD8 T cells, even at a single clonal level, are highly adaptive in antigen recognition such that they use weak binding kinetics to survive central and peripheral tolerance but greatly increase self-reactivity to precipitate disease. We will use a panel of monoclonal diabetogenic TCR cell clones based on the NOD mouse model of T1D to systemically characterize beta-cell antigen recognition during diabetogenic CD8 T cell thymocyte selection and peripheral activation and investigate a causal relationship between plasticity of beta-cell antigen recognition and autoimmune diabetes. In Aim2, we will elucidate the underlying mechanisms of beta-cell antigen recognition. We hypothesize that plasticity of beta-cell antigen recognition by diabetogenic CD8 T cells is due to CD8 binding kinetics with MHC. We will first define the role of CD8 in the overall beta-cell antigen recognition. We will then test a sub- hypothesis that unique patterns of CD8 glycosylation determine adaptability of CD8 binding kinetics by T cell glycan profiling, phenotyping, and single cell transcriptomic analysis.