Regulation of T Cell Responses in Atherosclerosis

描述(申请人提供)：慢性炎症是动脉粥样硬化的基本组成部分，由病变内针对抗原的T细胞促进。申请人实验室的工作已经确定了Th1细胞分化和B7家族共刺激分子对促动脉粥样硬化T细胞反应的重要性。尽管最近在T细胞调节领域有了重要的进展，但这方面的知识在动脉粥样硬化方面的应用还很少。我们的初步数据表明，在高胆固醇血症的背景下，调节性T细胞(Treg)存在系统性变化，T细胞共刺激分子ICOS与Treg活性之间存在潜在的重要联系。这项建议的目的是为了更好地了解限制促动脉粥样硬化T细胞反应的调控途径。提出了三个具体目标。在目标1中，我们将确定调节性T细胞(Treg)是否以及如何影响促动脉粥样硬化效应T细胞的反应和病变的发展。我们假设高胆固醇血症导致效应性CD4+T细胞反应和代偿性全身性Treg反应的增强。Treg将在LDLR KO小鼠的淋巴组织和病变中计数，包括FoxP3-GFP/LDLR报告小鼠。将对从LDLR KO小鼠分离的Treg进行功能分析，并将通过体内过继转移和耗竭研究来检验Treg对动脉粥样硬化的影响和CD4+T细胞对动脉粥样硬化抗原的反应。在目标2中，我们将描述T细胞上ICOS调节动脉粥样硬化病变发展和成熟的机制。我们假设ICOS通过增强Treg介导的对斑块抗原特异性效应T细胞的抑制和/或通过扭曲斑块抗原特异性效应T细胞的效应表型来发挥动脉粥样硬化保护作用。我们将分析ICOS和ICOS配体缺乏的LDLR KO小鼠的病变范围和表型，以及对动脉粥样硬化抗原的效应和Treg反应。将使用骨髓嵌合体和双KO小鼠。在目标3中，我们将确定PD-L1/PD-L2L-PD-1 T细胞调节通路是否影响动脉粥样硬化的发展和相关的T细胞反应。我们推测，表达在骨髓源性抗原提呈细胞或内皮细胞上的PD-L1和/或PD-L2与T细胞上的PD-1结合，从而限制T细胞对动脉粥样硬化抗原的反应。我们将使用缺乏PD-L1和PD-L2或PD-1的LDLR KO小鼠，使用骨髓嵌合体，以及复合KO小鼠。 动脉粥样硬化仍然是全世界发病率和死亡率的主要原因。成功完成这项提案中的目标将有助于更好地理解如何通过治疗控制加重动脉粥样硬化性疾病的免疫反应。

DESCRIPTION (provided by applicant): Chronic inflammation is a fundamental component of atherosclerosis, and is promoted by T-cells specific for antigens within lesions. Work in the applicant's laboratory has established the importance Th1 cell differentiation and B7-family costimulators to pro-atherogenic T cell responses. Although there have been important recent advances in the field of T cell regulation, there has been little application of this knowledge to atherosclerosis. Our preliminary data indicate that there are systemic changes in regulatory T cells (Treg) in the setting of hypercholesterolemia, and there is a potentially important connection between the T cell costimulatory molecule ICOS and Treg activity. The objective of this proposal is to achieve a better understand of the regulatory pathways that can limit pro-atherogenic T cell responses. Three specific Aims are proposed. In Aim 1, we will determine if and how regulatory T cells (Treg) influence pro-atherogenic effector T cells responses and lesion development. We hypothesize that hypercholesterolemia leads to enhancement of both effector CD4+ T cell responses and compensatory systemic Treg responses. Treg will be enumerated in lymphoid tissue and lesions in LDLR KO mice, including FoxP3-GFP/LDLR reporter mice. Functional assays will be performed on Treg isolated from LDLR KO mice, and Treg effects on atherosclerosis and CD4+ T cell responses to atheroantigens will be examined by in vivo adoptive transfer and depletion studies. In Aim 2, we will characterize the mechanisms by which the ICOS on T cells regulates atherosclerotic lesion development and maturation. We hypothesize that ICOS exerts an atheroprotective role by enhancing Treg-mediated suppression of plaque-antigen specific effector T cells and/or by skewing the effector phenotype of plaque-antigen specific effector T cells. We will analyze extent and phenotype of lesions, as well as effector and Treg responses to atheroantigens, in ICOS and ICOS ligand deficient LDLR KO mice. Bone marrow chimeras, and double KO mice will be employed. In Aim 3, we will determine if the PD-L1/PD-L2L-PD-1 T cell regulatory pathway influences the development of atherosclerosis and associated T cell responses. We hypothesize that PD-L1 and/or PD-L2, expressed on bone marrow derived antigen presenting cells or on endothelial cells bind to PD-1 on T cells and function to limit T cell responses to atheroantigens. We will employ LDLR KO mice deficient in PD-L1 and PD-L2 or PD-1, using bone marrow chimeras, and compound KO mice. Atherosclerosis remains a major cause of morbidity and mortality throughout the world. Successful completion of the Aims in this proposal will lead to a better understanding of how immune responses that aggravate atherosclerotic disease may be therapeutically controlled.