Thymic selection abnormalities in Type 1 Diabetes

1 型糖尿病的胸腺选择异常

• 批准号: 10717714
• 负责人: Megan Sykes
• 金额: $ 76.37万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-26 至 2028-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10717714
• 关键词: Affinity; Amino Acids; Antigens; Apoptosis; Apoptotic; Autoantigens; Autoimmune; Autoimmune Diabetes; Autoimmune Diseases; Autoimmunity; Autologous; Automobile Driving; Beta Cell; Binding; Cells; Clonal Deletion; Clone Cells; Data; Defect; Dependence; Development; Disease; Distal; Education; Event; Gene Transfer Techniques; Genes; Genetic; Genetic Polymorphism; Goals; Hematopoietic stem cells; Human; Hydrophobicity; Immune; Immune system; Impairment; Inbred NOD Mice; Insulin; Insulin deficiency; Insulin-Dependent Diabetes Mellitus; Islets of Langerhans; Knowledge; MHC Interaction; MHC antigen; Mediating; Mitogen-Activated Protein Kinases; Mus; Nature; Organ; Pathogenicity; Pathway interactions; Patients; Peptides; Peripheral; Population; Predisposition; Process; Receptor Signaling; Regulatory T-Lymphocyte; Relative Risks; Replacement Therapy; Role; SH2B gene; Signal Pathway; Signal Transduction; Single Nucleotide Polymorphism; Structure of beta Cell of islet; Structure of thymic cortex; T Cell Receptor Signaling Pathway; T-Cell Development; T-Cell Receptor; T-Lymphocyte; T-cell receptor repertoire; Thymocyte Selection; Thymus Gland; Tissues; Transgenes; Transgenic Organisms; Type I Insulin; autoreactive T cell; autoreactivity; central tolerance; complementarity-determining region 3; diabetes risk; genetic risk factor; genetic variant; induced pluripotent stem cell; insight; islet; islet autoimmunity; migration; mouse model; novel; risk variant; single-cell RNA sequencing; thymocyte; virtual

Project Summary Type 1 Diabetes (T1D) is an autoimmune disease in which T cells target insulin-producing β cells. At least 60 non-HLA genetic variants each confer small increases in T1D risk. While abnormal negative selection has been implicated in NOD mice, the possible role of aberrant thymic selection in driving human T1D is unknown. Human immune system (HIS) mice in which a patient’s immune system is generated de novo from their hematopoietic stem cells (HSCs), known as the personalized immune mouse (PIM) model, provide a unique opportunity to evaluate thymic selection events that contribute to T1D, permitting assessment of immune repertoire development and experimental manipulations such as T cell receptor (TCR) transgenesis. Our preliminary data suggest that non-HLA genetic variants associated with human T1D susceptibility confer both impaired negative selection and impaired Treg diversion of autoreactive thymocytes. By comparing T1D- and healthy control (HC)-derived PI mice, we have identified abnormalities in the thymic selection of two structural varieties of TCR in T1D immune systems. One (Type I) is characterized by longer than average CDR3βs with more hydrophobic amino acids and higher self-affinity and is normally most abundant in the Treg subset. Inserting a high affinity Type I insulin-reactive TCR (Clone 5) into HC HSCs resulted in clonal deletion or Treg diversion of thymocytes with this TCR. However, both processes are defective in T1D immune systems, resulting in entry of the islet autoreactive T cells into the peripheral repertoire only in T1D-derived immune systems. The second (Type II) is characterized by shorter CDR3β regions with few hydrophobic amino acids and shows greater islet autoreactive clonal survival in T1D compared to HC immune systems. Single cell RNAseq identified a major thymocyte population undergoing negative selection that highly expresses TCR signaling and pro-apoptotic genes. This cluster was virtually absent among T1D thymocytes, indicating a profound defect in the distal signaling pathways regulating thymic deletion. This impairment was associated with T1D susceptibility single nucleotide polymorphisms in SH2B3 and Erk/MAP kinase pathway genes. The overall goal of this proposal is to better understand the genetic control and abnormalities in thymic selection involved in the development of the autoimmune repertoires that mediate T1D. We propose to: 1): Further characterize defective thymocyte selection and identify the HSC-intrinsic, non-HLA genetically- determined TCR signaling defects in T1D that result in impaired negative selection and impaired Treg differentiation. We will also define pathogenic roles of Type I and Type II TCRs in T1D immune systems with autologous iPSC-derived β-cell grafts; 2) Utilize transgenic autoreactive TCRs and specific antigen-MHC tetramers to directly assess the extent of aberrant negative selection and Treg redirection in T1D-derived immune systems. Collectively, these studies will lead to novel insights into the mechanisms by which HLA and non-HLA risk alleles predispose to thymic selection of a T cell repertoire that causes islet autoimmunity.

项目摘要 1型糖尿病（T1 D）是一种自身免疫性疾病，其中T细胞靶向产生胰岛素的β细胞。至少60 非HLA遗传变异各自赋予T1 D风险的小幅增加。而反常的负选择 尽管在NOD小鼠中涉及胸腺选择，但异常胸腺选择在驱动人T1 D中的可能作用尚不清楚。 人免疫系统（HIS）小鼠，其中患者的免疫系统从其免疫系统从头产生。 造血干细胞（HSC），被称为个性化免疫小鼠（PIM）模型，提供了独特的 有机会评价导致T1 D的胸腺选择事件，允许评估免疫功能 库开发和实验操作，如T细胞受体（TCR）转基因。我们 初步数据表明，与人类T1 D易感性相关的非HLA遗传变异赋予了 自身反应性胸腺细胞的阴性选择受损和Treg转向受损。通过比较T1 D和 健康对照（HC）衍生的PI小鼠，我们已经确定了两个胸腺选择异常 T1 D免疫系统中TCR的结构多样性。一种（I型）的特点是长于平均值 CDR 3 β具有更多的疏水氨基酸和更高的自身亲和力，通常在Treg中最丰富 子集将高亲和力I型胰岛素反应性TCR（克隆5）插入HC HSC导致克隆缺失 或者用这种TCR使胸腺细胞的Treg转向。然而，这两个过程在T1 D免疫中都是有缺陷的。 系统，导致胰岛自身反应性T细胞仅在T1 D来源的 免疫系统第二种（II型）的特征是具有很少疏水性的较短CDR 3 β区 与HC免疫系统相比，T1 D中的胰岛自身反应性克隆存活率更高。 单细胞RNAseq鉴定了经历负选择的主要胸腺细胞群体， 表达TCR信号传导和促凋亡基因。该簇在T1 D胸腺细胞中几乎不存在， 表明调节胸腺缺失的远端信号通路存在严重缺陷。这种损害是 与SH 2B 3和Erk/MAP激酶通路中T1 D易感性单核苷酸多态性相关 基因.这项建议的总体目标是更好地了解胸腺的遗传控制和异常， 选择参与了介导T1 D的自身免疫谱系的发展。我们建议：1）： 进一步表征缺陷胸腺细胞选择并鉴定HSC-内在的，非HLA遗传- T1 D中确定的TCR信号传导缺陷导致阴性选择受损和Treg受损 分化我们还将定义I型和II型TCR在T1 D免疫系统中的致病作用， 自体iPSC衍生的β细胞移植物; 2）利用转基因自身反应性TCR和特异性抗原-MHC 四聚体直接评估T1 D衍生的细胞中异常阴性选择和Treg重定向的程度。 免疫系统总的来说，这些研究将导致新的见解的机制，HLA和 非HLA风险等位基因易受胸腺选择T细胞库的影响，导致胰岛自身免疫。