Insulin Specific T and B cells in Type 1 Diabetes

项目摘要 对胰岛抗原，特别是胰岛素原的适应性免疫应答在1型糖尿病中起着核心作用 (T1D)发育和病理学，T和B细胞都有助于疾病。众多大型 预防试验，主要使用胰岛素制剂（皮下、口服和鼻内）诱导耐受 并延迟临床症状的发作，一直不成功。有必要（1）研究 人T1 D靶器官内的自身免疫发病机制和（2）翻译免疫表型 从胰岛到高危受试者的血液。我们最近发现了胰岛素原反应性T细胞， 具有对胰岛素B链氨基酸9- 10应答的特异性T细胞受体（TCR）的T1 D器官供体的胰岛 图23示出了当转染到TCR无效细胞系中时由HLA-DQ 8呈递的图。这种T细胞也对分散的 整个人胰岛，从而将胰岛素B：9-23 T细胞反应性与人疾病发病机制联系起来。胰岛素B：9-23 特异性CD 4 T细胞存在于新发T1 D受试者的外周血中。高亲和力胰岛素- 在健康受试者的外周血中发现反应性B细胞，并且这些细胞局限于 无反应性B细胞区室（BND），因此是抗原无反应的。重要的是，在新发T1 D患者中， 以及一些携带高危HLA等位基因的一级亲属（FDR），这些B细胞失去无反应性。这些 这些发现使我们假设胰岛素特异性T细胞和B细胞在胰岛素分泌之前经历同源相互作用。 发展明显的疾病，并集中在胰岛和淋巴结，在那里他们传播 疾病这一假设将在两个具体目标中得到检验。利用胰腺器官捐赠者网络 （nPOD），目标1集中于定义胰岛反应性免疫细胞的抗原特异性、表型和功能 来自近期发病的T1 D的器官捐赠者的脾脏和胰岛。目标2是一项针对高危受试者的纵向研究 有≥2个胰岛自身抗体和HLA-DQ-DR匹配的自身抗体阴性一级亲属， TrialNet Pathway to Prevention（PTP）Living Biobank（以前称为自然史研究） 测量功能性胰岛素特异性T细胞应答，计数胰岛素结合B细胞，并表征 胰岛素自身抗体的抗原亲和力和亚型。拟议的研究将推进我们的长期目标 弥合靶器官和血液之间关于疾病进展生物标志物的知识的差距 并最终通过增强对疾病发病机制的理解来预防T1 D。

Project Summary The adaptive immune response to islet antigens, especially proinsulin, plays a central role in type 1 diabetes (T1D) development and pathology, with both T and B cells contributing to disease. Numerous large-scale prevention trials, mainly using preparations of insulin (subcutaneous, oral, and intranasal) to induce tolerance and delay the onset of clinical symptoms, have been unsuccessful. There exists the need to (1) study the autoimmune pathogenesis within the target organ of human T1D and (2) translate immunologic phenotypes from the islets to the blood of at risk subjects. We have recently identified proinsulin-reactive T cells from the islets of a T1D organ donor with a specific T cell receptor (TCR) responding to insulin B chain amino acids 9- 23 presented by HLA-DQ8 when transfected into a TCR null cell line. This T cell also responds to dispersed whole human islets, thus linking insulin B:9-23 T cell reactivity to human disease pathogenesis. Insulin B:9-23 specific CD4 T cells are present in the peripheral blood of new-onset T1D subjects. High affinity insulin- reactive B cells are found in the peripheral blood of healthy subjects, and these cells are restricted to the anergic B cell compartment (BND) and thus are antigen unresponsive. Importantly, in new-onset T1D patients and some first-degree relatives (FDRs) carrying high-risk HLA alleles, these B cells lose anergy. These findings lead us to hypothesize that insulin specific T and B cells undergo cognate interactions prior to the development of overt disease and concentrate in the pancreatic islets and lymph nodes where they propagate disease. This hypothesis will be tested in two specific aims. Utilizing the network for pancreatic organ donors (nPOD), Aim 1 focuses on defining antigen specificity, phenotypes and function of islet reactive immune cells from spleen and islets of organ donors with recent onset T1D. Aim 2 is a longitudinal study of at risk subjects with ≥2 islet autoantibodies and HLA-DQ-DR matched autoantibody negative first degree relatives from the TrialNet Pathway to Prevention (PTP) Living Biobank (previously referred to as the Natural History Study) measuring functional insulin specific T cell responses, enumerating insulin binding B cells, and characterizing insulin autoantibodies for antigen affinity and subtypes. The proposed studies will advance our long-term goal of bridging the gap of knowledge between the target organ and blood for biomarkers of disease progression and ultimately T1D prevention with enhanced understanding of disease pathogenesis.