Dendritic Cells in the Breaking of Peripheral Tolerance in Type 1 Diabetes

描述（由申请人提供）：1型糖尿病（T1 D）是最常见的儿童自身免疫性疾病，由T淋巴细胞介导的对产生胰岛素的胰腺β细胞的破坏引起。T1 D的显著免疫学特征在非肥胖糖尿病（NOD）小鼠中得到了很好的建模，其与人类T1 D患者一样表现出由CD 4+和CD 8 + T细胞介导的自发性自身免疫性糖尿病。虽然这些致糖尿病或致病的T细胞是不可或缺的细胞参与者，但它们的活化和功能成熟由先天性抗原呈递细胞（APC）控制，所述先天性抗原呈递细胞以打破正常外周T细胞耐受的方式获得、加工和呈递胰腺β细胞抗原。负责打破T细胞耐受性的APC和所涉及的分子机制尚未完全了解。众所周知，树突状细胞（DC）对于在炎症期间将外源抗原呈递给T细胞至关重要。然而，DC对凋亡自身细胞的清除通常被认为是非炎症性的，甚至是致耐受性的;事实上，许多研究表明，从凋亡细胞捕获抗原的DC迁移到局部淋巴结，在那里它们诱导T细胞耐受、无反应性或缺失。然而，在某些情况下，DC对凋亡细胞的吞噬可以是促炎性的，并导致自身反应性T细胞的引发;这被认为是T1 D易感个体或动物中凋亡胰腺β细胞的呈递的情况。最近，我们发现，一个子集的常规DC（cDC）是必要的启动致糖尿病的CD 4 + T细胞在体内。有趣的是，在该cDC群体中，我们的同事和双PI申请人Edith Janssen博士描述了一种新的DC亚群（CD 11 c + CD 11blo/-CD 4-CD 81-PDCA-1-），与其他cDC亚群相比，该亚群有效地（交叉）引发CD 4+和CD 8 + T细胞从凋亡细胞中产生自身抗原。这些细胞被称为部分细胞DC（mcDC），因为它们将凋亡细胞的颗粒储存在其细胞质中的离散的点状囊泡中，部分（<5A？C，particle，in Greek）.例如，遇到暴露于凋亡抗原的mcDC的CD 8 + T细胞不被赋予耐受性，而是显示增强的初级克隆扩增、细胞因子产生和效应子功能。此外，mcDC通过产生大量的1型干扰素来增强对凋亡自身的炎症免疫。基本原理：我们最近的研究发现，与其他品系相比，NOD小鼠中的mcDC不仅数量更多，而且生物活性更高。负载胰岛抗原的mcDC（i）从外周无反应性和缺失中拯救CD 8 + T细胞，（ii）刺激胰岛反应性CD 4 + T细胞，和（iii）将糖尿病转移至年轻NOD受体。此外，当从明显糖尿病NOD小鼠的胰腺淋巴结中纯化时，mcDC可以在体内打破外周T细胞对β细胞抗原的耐受，并在年轻NOD小鼠中诱导快速发作的T细胞介导的T1 D。因此，mcDC亚群似乎代表了长期寻求的关键抗原呈递细胞，其负责打破体内对β细胞抗原的外周耐受性。假设：总之，这些结果使我们假设mcDC是（i）负责致糖尿病性T细胞的引发并引起对胰岛抗原的免疫耐受的功能性破坏的关键CD 11 c + DC亚群，以及（ii）驱动NOD小鼠中T1 D所需的1型干扰素的主要储库。为了提供对这些假设的直接检验，我们提出了以下具体目标：目标1：确定胰岛抗原喂养的mcDC打破NOD小鼠中CD 4+和CD 8 + T细胞耐受的方法。初步数据显示，从凋亡β细胞获得和呈递自身抗原破坏了体内外周CD 4+和CD 8 + T细胞耐受。目的2：明确mcDC产生1型干扰素在NOD小鼠T1 D发生中的分子作用。 公共卫生相关性：1型糖尿病（T1 D）是最常见的儿童自身免疫性疾病，由T淋巴细胞介导的对产生胰岛素的胰腺β细胞的破坏引起。T1 D的显著免疫学特征在非肥胖糖尿病（NOD）小鼠中得到了很好的建模，其与人类T1 D患者一样表现出由CD 4+和CD 8 + T细胞介导的自发性自身免疫性糖尿病。虽然这些致糖尿病或致病的T细胞是不可或缺的细胞参与者，但它们的活化和功能成熟由先天性抗原呈递细胞（APC）控制，所述先天性抗原呈递细胞以打破正常外周T细胞耐受的方式获得、加工和呈递胰腺β细胞抗原。负责打破T细胞耐受性的APC和所涉及的分子机制尚未完全了解。最近，我们发现，一个子集的常规DC（cDC）是必要的启动致糖尿病的CD 4 + T细胞在体内。有趣的是，在这个cDC群体中，我们的同事和双PI申请人Edith Janssen博士描述了一种称为分细胞DC（mcDC）的新型DC亚群，其将凋亡细胞的颗粒储存在其细胞质中的离散点状囊泡中。此外，mcDC通过产生大量的1型干扰素来增强对自身组织的炎症免疫。我们最近的研究发现，与其他品系相比，NOD小鼠中的mcDC不仅数量更多，而且生物活性更高。我们假设mcDC是（i）负责致糖尿病性T细胞的启动并引起对胰岛抗原的免疫耐受的功能性破坏的关键CD 11 c + DC亚群，以及（ii）驱动NOD小鼠中T1 D所需的1型干扰素的主要储库。

DESCRIPTION (provided by applicant): Type 1 diabetes (T1D), the most common childhood autoimmune disease, is caused by the T lymphocyte-mediated destruction of insulin-producing pancreatic beta cells. The salient immunological features of T1D are well-modeled in the non-obese diabetic (NOD) mouse, which like human T1D patients exhibit spontaneous autoimmune diabetes mediated by both CD4+ and CD8+ T cells. While these diabetogenic, or disease-causing, T cells are indispensable cellular participants, their activation and functional maturation are controlled by the innate antigen presenting cells (APC) which acquire, process and present pancreatic beta cell antigen in a manner that breaks normal peripheral T cell tolerance. The APC responsible for breaking T cell tolerance and the molecular mechanism involved is not well understood. It is well appreciated that dendritic cells (DC) are crucial for presenting foreign antigen to T cells during times of inflammation. Yet, the clearance of apoptotic self cells by DC is generally considered to be non-inflammatory, even tolerogenic; in fact, numerous studies have shown that DC that capture antigen from apoptotic cells migrate to local lymph nodes, where they induce T cell tolerance, anergy or deletion. Yet, under certain situations phagocytosis of apoptotic cells by DC can be pro-inflammatory and lead to the priming of self-reactive T cells; this is thought to be the case for the presentation of apoptotic pancreatic beta cells in T1D-prone individuals or animals. Recently, we found that a subset of conventional DC (cDC) are necessary for priming diabetogenic CD4+ T cells in vivo. Interestingly, within this cDC population, our colleague and dual-PI applicant, Dr. Edith Janssen, described a novel DC subset (CD11c+CD11blo/-CD4-CD81-PDCA-1-) that in contrast to other cDC subsets potently (cross-)primes both CD4+ and CD8+ T cells to self-antigen from apoptotic cells. These cells are termed merocytic DC (mcDC) since they stored particles of apoptotic cells in discrete, punctate vesicles in their cytoplasm, meros (<5A?C, particle, in Greek). For example, CD8+ T cells that encounter mcDC exposed to apoptotic antigen are not rendered tolerant, but rather display enhanced primary clonal expansion, cytokine production and effector function. Moreover, mcDC enhance inflammatory immunity to apoptotic self in part by producing copious levels of type 1 interferons. Rationale: Our recent studies have found that mcDC are not only more numerous but also more biologically active in NOD mice compared to other strains. Islet antigen-loaded mcDC (i) rescue CD8+ T cells from peripheral anergy and deletion, (ii) stimulate islet-reactive CD4+ T cells, and (iii) transfer diabetes to young NOD recipients. Moreover, when purified from the pancreatic lymph nodes of overtly diabetic NOD mice, mcDC can break peripheral T cell tolerance to beta cell antigens in vivo and induce rapid onset T cell-mediated T1D in young NOD mouse. Thus, the mcDC subset appears to represent the long-sought critical antigen presenting cell responsible for breaking peripheral tolerance to beta cell antigen in vivo. Hypothesis: Together, these results lead us to hypothesize that mcDC are (i) the critical CD11c+ DC subset responsible for the priming of diabetogenic T cells and cause the functional break in immune tolerance to islet antigen, and (ii) a major reservoir of type 1 interferon needed to drive T1D in NOD mice. To provide a direct test of these hypotheses, we propose the following specific aims: Aim 1: To identify the means by which islet-antigen-fed mcDC break CD4+ and CD8+ T cell tolerance in the NOD mouse. Preliminary data shows that the acquisition and presentation of self-antigen from apoptotic beta cells breaks peripheral CD4+ and CD8+ T cell tolerance in vivo. Aim 2: To define the molecular role of type 1 interferon production by mcDC in the development of T1D in the NOD mouse. PUBLIC HEALTH RELEVANCE: This application focuses on Type 1 diabetes (T1D), the most common childhood autoimmune disease, is caused by the T lymphocyte-mediated destruction of insulin-producing pancreatic beta cells. The salient immunological features of T1D are well-modeled in the non-obese diabetic (NOD) mouse, which like human T1D patients exhibit spontaneous autoimmune diabetes mediated by both CD4+ and CD8+ T cells. While these diabetogenic, or disease-causing, T cells are indispensable cellular participants, their activation and functional maturation are controlled by the innate antigen presenting cells (APC) which acquire, process and present pancreatic beta cell antigen in a manner that breaks normal peripheral T cell tolerance. The APC responsible for breaking T cell tolerance and the molecular mechanism involved is not well understood. Recently, we found that a subset of conventional DC (cDC) are necessary for priming diabetogenic CD4+ T cells in vivo. Interestingly, within this cDC population, our colleague and dual-PI applicant, Dr. Edith Janssen, described a novel DC subset termed merocytic DC (mcDC) which store particles of apoptotic cells in discrete, punctate vesicles in their cytoplasm. Additionally, mcDC enhance inflammatory immunity to self tissue in part by producing copious levels of type 1 interferons. Our recent studies have found that mcDC are not only more numerous but also more biologically active in NOD mice compared to other strains. We hypothesize that mcDC are (i) the critical CD11c+ DC subset responsible for the priming of diabetogenic T cells and cause the functional break in immune tolerance to islet antigen, and (ii) a major reservoir of type 1 interferon needed to drive T1D in NOD mice.