Perturbation of B cell anergy in T1D

 描述(申请人提供)：1型糖尿病(T1D)是一种自身免疫性疾病，其特征是免疫系统攻击和胰腺中产生胰岛素的胰岛β细胞被破坏。据估计，这种疾病影响了300万美国人和全球3000万人，而且频率还在继续增加。鉴于这种疾病对世界健康的影响，而且没有治愈的方法，迫切需要进行研究，以了解其病因和病理生理学。尽管人们普遍认为T细胞是β细胞的执行者，但目前尚不清楚在疾病中是什么事件先于并加速了T细胞的活动。这里提出的研究将扩展我们最近发表的关于胰岛素反应性B细胞在T1D发育中的作用的发现。在非肥胖糖尿病(NOD)小鼠模型中的研究表明，胰岛抗原反应性B细胞是T1D发生所必需的，并进一步表明这些B细胞是胰腺中糖尿病T细胞激活和增殖所必需的。B细胞在人类疾病中的作用还不是很清楚。然而，这些细胞的作用得到了B细胞耗竭治疗(利妥昔单抗)在T1D中的成功支持。我们最近发现，在健康受试者中，携带高亲和力胰岛素结合抗原受体的B细胞存在于无能的所谓的BND室，但在所有新发糖尿病和糖尿病前期患者中，可能最重要的是，在他们健康但有风险的一级亲属(FDR)中，B细胞离开了这个室。这些发现表明，在与1型糖尿病患者具有相似环境暴露和基因型的健康个体中，B细胞无能可能丢失，因此可能是由这些因素驱动的T1D的易感或启动事件。我们进一步证明，BND B细胞表达的胰岛素反应性抗原受体与染色质和脂多糖发生交叉反应。因此，在疾病发展的背景下，BNDS可能是通过携带共刺激TLR配体的染色质聚集体而不是胰岛素来激活的。在这个R21应用中，我们建议将这些发现扩展到三个目标。在目标1中，我们将确定BNDS的逃逸是否只发生在携带有自身免疫风险的特定遗传等位基因的FDR中。某些风险等位基因是否会损害B细胞无能？在目标2中，我们将分析新发糖尿病患者胰岛来源的B细胞，确定它们是否被激活并表达与BND来源一致的高胰岛素亲和力、多反应抗原受体。这些细胞可能是停留在胰岛中的BNDS激活的吗？在目标3中，我们将评估BND细胞的早期逃逸是否是T1D所特有的，或者也发生在其他自身免疫性疾病中，例如狼疮或自身免疫性甲状腺疾病。这是自身免疫中的普遍事件吗？

 DESCRIPTION (provided by applicant): Type 1 Diabetes (T1D) is an autoimmune disease characterized by immune system attack and destruction of insulin-producing islet beta cells in the pancreas. The disease affects an estimated three million Americans and 30 million people worldwide, and continues to increase in frequency. Given the impact of this disease on world health and the absence of a cure, there is critical need for studies directed at understanding its etiology and pathophysiology. Although it is well accepted that T cells function as the beta cell executioners, it is unclear what events precede and precipitate their activity in disease. The studies proposed here will extend our recently published findings suggesting a role for insulin-reactive B cells in T1D development. Studies in the Non-Obese Diabetic (NOD) mouse model demonstrate that islet antigen-reactive B cells are required for development of T1D, and further indicate that these B cells are necessary for activation and proliferation of diabetogenic T cells in the pancreas. The function of B cells in human disease is less well understood. However, a role for these cells is supported by the success of B cell depleting therapy (Rituximab) in T1D. We have recently shown that in healthy subjects B cells bearing high affinity insulin-binding antigen receptors reside in the anergic, so-called BND, compartment, but leave this compartment in all new onset diabetic and prediabetic patients, and, perhaps most importantly, in a proportion of their healthy but "at risk" first degree relatives (FDRs). These findings suggest that B cell anergy can be lost in healthy individuals with similar environmental exposure and genotype as type 1 diabetics, and thus may be a predisposing or initiating event in T1D driven by these factors. We have further shown that insulin-reactive antigen receptors expressed by BND B cells are crossreactive with chromatin and lipopolysaccharide. Thus, in the context of disease development, BNDs may be activated by chromatin aggregates carrying co-stimulatory TLR ligands, rather than insulin. In this R21 application we propose to extend these findings in three aims. In Aim 1 we will determine whether escape of BNDs occurs only in FDRs carrying particular genetic alleles that confer risk of autoimmunity. Might certain risk alleles compromise B cell anergy? In Aim 2 we will analyze B cells derived from pancreatic islets of new-onset diabetic patients, determining whether they are activated and express high insulin affinity, polyreactive antigen receptors, consistent with BND origin. Could these cells be activated BNDs that have lodged in islets? In Aim 3 we will assess whether early escape of BND cells is peculiar to T1D, or also occurs in other autoimmune diseases, i.e. lupus or autoimmune thyroid disease. Is this a generalized event in autoimmunity?