T Cell Tolerance by DEC-205-mediated Islet Antigen Delivery to Dendritic Cells

描述（由申请人提供）：1型糖尿病（T1 D）是一种自身免疫性疾病，其特征在于T细胞介导的胰岛β细胞破坏。我们对NOD小鼠模型和T1 D患者中T细胞靶向的至少一些β细胞抗原的了解现在可以实际用于开发基于抗原的策略，以干扰致病性T细胞群并增强天然耐受诱导途径。我们假设T1 D的有效免疫策略是消除对重要β细胞抗原特异性的致病性CD 8+和CD 4 + T细胞，同时促进能够控制靶向各种β细胞抗原的剩余致病性T细胞的调节性T细胞（Treg）的扩增。我们将开发这样一种方法，利用我们的经验，在靶向抗原的树突状细胞（DC）使用抗原连接的抗体DC内吞受体DEC- 205。当在不存在佐剂的情况下以这种方式递送抗原时，DC以致耐受性方式呈递抗原，并导致幼稚T细胞被删除、变得无应答或被赋予调节特征。使用我们最近生产的试剂，我们建议将β细胞抗原胰岛素原递送至DC，并确定这种治疗对致病性CD 8+和CD 4 + T细胞以及对Treg诱导的影响。这些研究将采用我们开发的基于NOD的小鼠模型（命名为NOD.22mnull.HHD.Ins2+/-），其转基因表达T1 D相关的人HLA-A*0201，并且对于Ins 2敲除等位基因也是杂合的，这导致胸腺胰岛素表达减少，因此模拟了大多数T1 D患者的情况。还将采用并入人细胞的最先进的小鼠模型。最后，我们的实验系统将是理想的，以确定抗原靶向DC可以导致诱导T细胞耐受的途径。本研究提出了三个具体目的：（1）通过DEC-205将胰岛素原靶向DC，并监测其对NOD.22mnull.HHD.Ins2+/-小鼠中T细胞和T1 D发展的影响;（2）确定人胰岛反应性T细胞是否可以响应DEC-205介导的β细胞抗原向DC的递送而耐受;（3）确定在响应DEC-205介导的β细胞抗原向DC的递送中观察到的T细胞耐受的重要途径。我们提出的研究将对T1 D抗原特异性治疗的发展产生重要影响，并将提供有助于指导这种疾病免疫调节治疗未来发展的信息。

DESCRIPTION (provided by applicant): Type 1 diabetes (T1D) is an autoimmune disease characterized by T cell-mediated destruction of the pancreatic islet beta cells. Our knowledge of at least some of the beta cell antigens targeted by T cells in both the NOD mouse model and T1D patients can now be used practically to develop antigen-based strategies to interfere with pathogenic T cell populations and augment natural tolerance induction pathways. We hypothesize that an effective immunotherapeutic strategy for T1D would be one that eliminates pathogenic CD8+ and CD4+ T cells specific for an important beta cell antigen, while at the same time fostering the expansion of regulatory T cells (Treg) capable of controlling the remaining pathogenic T cells that target a variety of beta cell antigens. We will develop such an approach by taking advantage of our experience in the targeting of antigens to dendritic cells (DC) using antigen-linked antibodies to the DC endocytic receptor DEC- 205. When antigens are delivered in this way in the absence of an adjuvant, DC present them in a tolerogenic manner and cause naive T cells to be deleted, rendered unresponsive, or endowed with regulatory characteristics. Using a reagent that we have recently produced, we propose to deliver the beta cell antigen proinsulin to DC and determine the effect of this treatment on pathogenic CD8+ and CD4+ T cells and on the induction of Treg. These studies will employ an NOD-based mouse model that we have developed (designated NOD.22mnull.HHD.Ins2+/-) that transgenically expresses T1D-associated human HLA-A*0201 and is also heterozygous for an Ins2 knockout allele which leads to diminished thymic insulin expression, hence mimicking the situation in the majority of T1D patients. State-of-the-art mouse models incorporating human cells will also be employed. Finally, our experimental systems will be ideal to determine the pathways by which targeting of antigens to DC can lead to induction of T cell tolerance. Three Specific Aims are proposed: (1) To target proinsulin to DC via DEC-205 and monitor its effects on T cells and the development of T1D in NOD.22mnull.HHD.Ins2+/- mice; (2) To determine whether human islet-reactive T cells can be tolerized in response to DEC-205-mediated delivery of beta cell antigens to DC; (3) To determine the pathways important for the T cell tolerance observed in response to DEC-205-mediated delivery of beta cell antigens to DC. Our proposed studies will have important implications for the development of antigen-specific therapeutics for T1D and will provide information that will help to guide the future development of immunomodulatory therapies for this disease.