T cell-tissue interaction models

 描述（由申请人提供）：本 R21 提案是对题为“用于研究的动物模型和相关生物材料的开发”的 PA-13-145 的直接回应。该提案的目标是开发两种新的动物模型，以满足免疫学、病毒学和干细胞医学等广泛领域中未满足的主要需求。所有有核细胞的表面都覆盖有 MHC I 类分子，这些分子呈现源自细胞内蛋白质的肽。 T 细胞扫描细胞表面，只与那些其自身的细胞接触 T 细胞受体对特定的 MHC 肽复合物具有亲和力。一旦 T 细胞参与，结果高度依赖于呈递抗原的细胞和局部环境。不同的细胞类型会导致不同的 T 细胞反应；例如，一些细胞可能会引导 CD4 T 细胞分化为效应细胞，而其他细胞的呈递可能会引导它们成为调节细胞。 T 细胞如何与特定细胞类型相互作用是免疫学中最重要的问题之一。这个答案可以告诉我们为什么某些细胞类型更容易发生自身免疫反应，以及为什么其他细胞类型（例如癌细胞）可能不太容易被 T 细胞杀死。虽然我们知道 T 细胞如何与某些细胞类型发生反应，但仍有许多细胞类型与 T 细胞的相互作用从未被研究过。例如，我们不知道 T 细胞如何与多种类型的干细胞相互作用。我们假设，如果绿色荧光蛋白 (GFP) 可以用作模型抗原，那么可以研究 T 细胞与多种细胞类型的相互作用，这些细胞类型（包括许多类型的干细胞）以前未曾研究过。目标 1 的目标是培育 T 细胞识别 I 类或 II 类 MHC 中存在的 GFP 表位的小鼠。目标 1 的结果将建立一个针对常用、易于监控的荧光报告基因的抗原特异性 T 细胞模型。由于 GFP 特异性 CD8 T 细胞可以杀死表达 GFP 的细胞，因此我们假设，如果感兴趣的细胞类型表达 GFP，则 GFP 特异性 CD8 T 细胞可用于选择性消除小鼠中几乎任何细胞群。我们已经获得了初步数据，表明我们可以使用 GFP 特异性 T 细胞来杀死脾脏、胰腺、肠道和心脏中表达 GFP 的细胞。目标 2 的目的是将 T 细胞介导的细胞消融与白喉毒素 (DT) 介导的细胞消除进行比较，并确定我们如何有效地使用 GFP 特异性 T 细胞来杀死大脑中的细胞。这些研究的结果将建立一种新的细胞耗竭方法，可用于数百只现有的细胞类型特异性 GFP 表达小鼠，并且它可能比 DT 介导的耗竭具有更少的炎症。丰富的基于 GFP 的试剂和动物模型使得 GFP 特异性 T 细胞小鼠与众多进行各种研究的实验室相关，包括但不限于：(i) 了解特定细胞类型的抗原呈递能力，(ii) 模拟自身免疫破坏，(iii) 病原体与 T 细胞相互作用的表征，以及 (iv) 识别特定细胞的功能 体内的细胞。

 DESCRIPTION (provided by applicant): This R21 proposal is in direct response to PA-13-145, entitled "Development of Animal Models and Related Biological Materials for Research". The goal of this proposal is to develop two new animal models to fill major unmet needs in a broad array of fields, including immunology, virology, and stem cell medicine. The surface of all nucleated cells are covered in MHC class I molecules that present peptides derived from proteins made in the cell. T cells scan the surface of a cell, and engage only cells in which their T cell receptor has affinity for a specific MHC-peptide complex. Once the T cell engages, the outcome is highly dependent on the cell presenting the antigen and the local context. Different cell types can result in different T cell responses; for example some cells may direct CD4+ T cell to differentiate into an effector, whereas presentation by other cells may direct them to become regulatory. How a T cell interacts with a particular cell type is one of the most important questions in immunology. The answer can tell us why some cell types are more prone to autoimmune responses, and why other cell types, such as cancer cells, may be less prone to T cell killing. While we know how T cells react with some cell types, there are many cell types whose interaction with T cells has never been studied. For example, we do not know how T cells interact with many types of stem cells. We hypothesize that if green florescent protein (GFP) can be utilized as a model antigen, than T cell interactions with numerous cell types, which were not previously studied including many types of stem cells, can be investigated. The objective of Aim 1 is to generate mice in which the T cells recognize an epitope of GFP presented in MHC class I or II. The outcome of Aim 1 would establish an antigen-specific T cell model that targets a commonly used, easily monitored, florescent reporter. Since GFP-specific CD8+ T cells can kill GFP-expressing cells, we hypothesize that GFP-specific CD8+ T cells can be used to selectively deplete almost any cell population in a mouse, if the cell type of interest s expressing GFP. We have already obtained preliminary data showing that we can use GFP-specific T cells to kill GFP expressing cells in the spleen, pancreas, gut, and heart. The objective of Aim 2 is to compare T cell mediated cell ablation to diphtheria toxin (DT)-mediated depletion, and to determine how effectively we can use the GFP-specific T cells to kill cells in the brain. The outcome of these studies will establish a new method of cell depletion that can be used with the 100s of cell type-specific GFP expressing mice that already exist, and it is potentially less inflammatory than DT-mediated depletion. The abundance of GFP-based reagents and animal models makes the GFP-specific T cell mice relevant for numerous labs doing a wide variety of research including, but not limited to: (i) understanding the antigen presenting capacity of specific cell types, (ii) modeling autoimmune destruction, (iii) characterization of pathogen-T cell interactions, and for (iv) identifying the function of specific cells in vivo.