MerTK Mediated T Cell Suppression in the Pancreatic Islets During Type 1 Diabetes

项目总结： 当1型糖尿病(T1D)患者出现疾病时，他们的免疫系统已经破坏了大部分 它们胰岛中的β细胞。剩余的产生胰岛素的胰岛可能已经渗透到 白细胞，但剩余的β细胞团有助于维持血糖控制，导致较少 糖尿病相关并发症。因此，控制胰岛的免疫反应，特别是T细胞，是 对于保存剩余的胰岛素产生和防止T1D进展至关重要。我们的 研究表明，胰岛的免疫反应是暂时调节的。致病性T细胞刺激 胰岛内出现在胰岛浸润期的早期。然而，随着胰岛浸润的进展，T细胞在胰岛中的重新刺激 胰岛至少通过一种未定义的机制暂时被抑制。我们的初步数据正在耗尽 CD11c细胞表明，CD11c细胞负责抑制胰岛中T细胞的再刺激。 随着胰岛浸润的进展，胰岛CD11c细胞对T细胞的作用不同，提示胰岛CD11c 随着时间的推移，种群数量可能会有所不同。然而，关于特定的CD11c细胞的知识存在差距。 在胰岛渗透过程中存在于胰岛中的亚群，每个CD11c亚群在 调节胰岛T细胞的致病性及CD11c细胞介导的T细胞抑制机制 在小岛上。我们发现了一个表达MerTK的胰岛浸润性CD11c群体。MerTK是一种受体 介导细胞凋亡摄取的酪氨酸激酶，此前已被认为与T细胞耐受有关 NOD小鼠T1D。值得注意的是，我们的初步数据显示，MerTK抑制导致了T1D的快速发作 无症状的晚期胰岛浸润性NOD小鼠。基于这些发现，我们假设 胰岛CD11c细胞亚群通过一种途径抑制胰岛T细胞的再刺激和效应功能 MerTK依赖机制。为了验证这一假设，我们将使用各种方法来实现以下目标 技术包括活体双光子显微镜、单细胞rna-seq、流式细胞术和疾病分析。 进步。目的1：确定CD11c细胞和MerTK在抑制T细胞功能中的作用 胰岛内的细胞致病性。目的2：鉴定胰岛CD11c亚群并确定其作用机制 哪些CD11c MerTK细胞在T1D期间促进了胰岛的耐受。目的3：鉴定单个核细胞 T_1D进展过程中人胰岛吞噬细胞群和MerTK的表达及意义 T1D时MerTK的表达或功能是否发生改变。了解T细胞抑制的机制 通过解决这些目标，我们可以在治疗上加强这些途径，以保护贝塔病毒 自身抗体阳性糖尿病前期或新发患者的细胞质量、胰岛素产生和血糖控制 糖尿病患者。

PROJECT SUMMARY: When type 1 diabetes (T1D) patients present with disease, their immune system has already destroyed most of the beta cells in their pancreatic islets. Remaining insulin-producing islets may already be infiltrated with leukocytes, but remaining beta cell mass is instrumental for maintaining blood glucose control, leading to fewer diabetes-related complications. Therefore, controlling the immune response in the islets, particularly T cells, is of paramount importance for preserving remaining insulin production and preventing T1D progression. Our work has shown that the immune response in the islets is temporally regulated. Pathogenic T cell stimulation within the islets occurs early in islet infiltration. However, as islet infiltration advances, T cell restimulation in the islets is at least transiently suppressed, through an undefined mechanism. Our preliminary data depleting CD11c+ cells indicate that CD11c+ cells are responsible for this suppression of T cell restimulation in the islets. Islet CD11c+ cells have differing effects on T cells as islet infiltration progresses, suggesting that islet CD11c+ populations might differ over time. However, there is a gap in knowledge about the specific CD11c+ cell subsets that are present in the islets over the course of islet infiltration, the role of each CD11c+ subset in modulating T cell pathogenicity in the islets, and the mechanisms of CD11c+ cell-mediated T cell suppression in the islets. We found an islet-infiltrating CD11c+ population that expresses MerTK. MerTK is a receptor tyrosine kinase that mediates apoptotic cell uptake and that has previously been implicated in tolerizing T cells during T1D in NOD mice. Strikingly, our preliminary data show that MerTK inhibition induced rapid T1D onset in asymptomatic NOD mice with advanced islet infiltration. Based on these findings, we hypothesize that a subset of islet-infiltrating CD11c+ cells suppress T cell restimulation and effector function in the islets via a MerTK dependent mechanism. To test this hypothesis, we will address the following aims using a variety of techniques including in vivo 2-photon microscopy, single cell RNA-seq, flow cytometry, and analysis of disease progression. Aim 1: To determine the function of islet-infiltrating CD11c+ cells and of MerTK in suppressing T cell pathogenicity within the islets. Aim 2: To identify islet CD11c+ subsets and determine mechanisms by which CD11c+MerTK+ cells promote tolerance in the islets during T1D. Aim 3: To identify the mononuclear phagocyte populations and MerTK expression in human islets during T1D progression and to determine whether MerTK expression or function is altered in T1D. Understanding the mechanisms of T cell suppression in the islets by addressing these aims could allow us to therapeutically reinforce these pathways to protect beta cells mass, insulin production, and blood glucose control in autoantibody-positive pre-diabetic or new-onset diabetic patients.