B Cells and Type 1 Diabetes

描述（由申请人提供）：自身免疫影响近一千万美国人，并且由于未知原因，频率正在增加。现有证据表明，自身免疫性疾病的发生是由于遗传决定的易感性和先天免疫刺激的组合，其合谋刺激对自身的适应性免疫。自身免疫的基础是T细胞和/或B细胞区室中对自身的免疫耐受的破坏。虽然我们对维持B细胞耐受性的机制了解很多，但我们对导致其在自身免疫中失败的机制知之甚少。在本申请中，我们提出研究在鼠和人1型糖尿病中B细胞对胰岛素耐受性丧失中起作用的机制，1型糖尿病是一种已知需要B细胞的疾病，该疾病被认为通过抗原呈递给CD 4 T细胞而起作用。我们的方法将建立在我们以前的工作，定义信号转导通路在维持抗原无反应性B细胞。我们将通过流式细胞术分析胰岛素特异性B细胞状态的变化，这些细胞是使用基于磁珠的新方法从正常、糖尿病前期和糖尿病小鼠和患者中分离的。在某些情况下，免疫球蛋白重链转基因将用于产生尽管如此在胰岛素特异性细胞中富集的多样化抗原受体库。目的1将探讨正常小鼠外周血胰岛素特异性B细胞是如何沉默的，以及这种沉默在糖尿病小鼠中是否被打破。在目的2中，我们将研究抗原受体对胰岛素的亲和力在决定沉默模式、命运和糖尿病发生潜力中的作用。这将涉及一种逆转录转基因方法，以产生具有确定的抗原受体对胰岛素亲和力的库。在目标3中，我们将研究扩展到人类，比较糖尿病前期和糖尿病个体与非糖尿病一级亲属中的胰岛素特异性B细胞。最后，在目标4中，我们将评估新型B细胞脱敏疗法在T1 D中的治疗功效，将该疗法与消耗B细胞的抗CD 20进行比较。这些实验将解决以下总体假设：在1型糖尿病中，高亲和力胰岛素特异性B细胞的沉默被打破，这些细胞通过将自身抗原呈递给CD 4 T细胞来促进疾病。

DESCRIPTION (provided by applicant): Autoimmunity affects nearly ten million Americans and, for unknown reasons, is increasing in frequency. Available evidence indicates that autoimmune diseases arise due to a combination of genetically determined susceptibility and innate immune stimulation, which conspire to stimulate adaptive immunity to self. Underpinning autoimmunity is the breakdown of immune tolerance to self in T cell and/or B cell compartments. While a great deal is known about the mechanisms that maintain B cell tolerance, we understand little about the mechanisms that cause it to fail in autoimmunity. In this application we propose to study mechanisms operative in loss of B cell tolerance to insulin in murine and human Type 1 Diabetes, a disease known to require B cells that are thought to function by antigen presentation to CD4 T cells. Our approach will build upon our previous work defining signaling pathways operative in maintaining antigen unresponsiveness of anergic B cells. We will analyze by flow cytometry changes in the status of insulin-specific B cells isolated using a novel magnetic bead-based approach from normal, prediabetic and diabetic mice and patients. In some cases immunoglobulin heavy chain transgenesis will be used to generate a diverse antigen receptor repertoire that is nonetheless enriched in insulin-specific cells. Aim 1 will explore how peripheral insulin-specific B cells are silenced in normal mice and whether this silencing is breached in diabetic mice. In Aim 2 we will study the role of antigen receptor affinit for insulin in determining mode of silencing, fate and diabetogenic potential. This will involve a retrotransgenic approach to generate a repertoire with defined antigen receptor affinity for insulin. In Aim 3 we will extend studies to the human, comparing insulin-specific B cells in prediabetic and diabetic individuals to non-diabetic first- degree relatives. Finally, in Aim 4 we will assess the therapeutic efficacy in T1D of a novel B cell desensitizing therapy, comparing this therapy to anti-CD20, which depletes B cells. The experiments will address the overarching hypothesis that in Type 1 Diabetes the silence of high affinity insulin-specific B cells is broken and these cells promote disease by presentation of autoantigen to CD4 T cells.