Protection of the Heart by PD-1 and PD-L1

描述（由申请人提供）：心肌炎症是对缺血性损伤、感染和自身反应性或同种异体反应性淋巴细胞活化的反应。心肌功能受到炎症介质的损害，炎症导致慢性心肌损伤、纤维化和心力衰竭。先天性和适应性免疫反应在心脏中受到严格调节，这有助于防止适应不良的炎症。尽管如此，这些机制知之甚少，当它们失败时，炎症反应是心肌疾病发病机制的核心。更好地理解抑制心肌炎症的正常机制是设计治疗策略以限制几种心脏疾病中的炎症损伤的关键。广泛的初步工作已经证明，分子PD-1及其配体PD-L1是对微生物、同种异体反应性和自身抗原的适应性免疫应答的重要调节剂。特别是，PD 1/PD L1通路似乎是控制心脏免疫应答的中心负调控检查点。然而，由于PD-1和PD-L1的细胞表达的复杂性，目前还不清楚该途径实际上是如何参与抑制心肌炎症的。 该项目的广泛目标是发现心脏炎症如何受到内皮细胞，肌细胞和树突状细胞PD-L1以及髓样PD-1的调节。这项工作将利用新开发的具有PD-L1和PD-1谱系特异性缺陷的小鼠品系，这些小鼠品系将用于先天性和适应性免疫介导的心肌炎症模型的背景下。这些方法将被组织成以下三个具体目标：目标1。确定哪些细胞类型介导PD-L1依赖性保护作用，以对抗心脏中的T细胞，保护机制以及在治疗上参与这些机制的可行性。目标二。检验PD-1-PD-L1通路直接调节心脏中髓样细胞炎症反应的假设。目标3：开发PD-1：PD-L1依赖性方法，以治疗诱导T细胞对心肌抗原的耐受性完成这些目标生成的数据将首次定义内皮细胞、心肌细胞和DC PD-L1对心脏炎症的调节，以及骨髓PD-1。这些发现对于开发治疗心肌炎症的治疗方法以及了解阻断PD-1和PD-L1的治疗方法的风险非常重要，这些方法正在癌症和慢性病毒感染中积极开发。

DESCRIPTION (provided by applicant): Myocardial inflammation occurs in in response to ischemic injury, infections, and activation of autoreactive or alloreactive lymphocytes. Myocardial function is impaired by inflammatory mediators, and inflammation contributes to chronic myocardial injury, fibrosis, and heart failure. Innate and adaptive immune responses are tightly regulated in the heart, which serves to prevent maladaptive inflammation. Nonetheless, these mechanisms are poorly understood, and when they fail, inflammatory responses are central to the pathogenesis of myocardial disease. A better understanding of the normal mechanisms that suppress myocardial inflammation is key to the design of therapeutic strategies to limit inflammatory damage in the setting of several cardiac diseases. Extensive preliminary work has demonstrated that the molecules PD-1 and its ligand PD-L1 are important regulators of adaptive immune responses to microbial, alloreactive and self- antigens. In particular, the PD 1/PD L1 pathway appears to be a central negative regulatory checkpoint in controlling immune responses in the heart. However, because of the complexities of the cellular expression of PD-1 and PD-L1, it is still unclear how the pathway is actually engaged to suppress myocardial inflammation. The broad objectives of this project are to discover how cardiac inflammation is regulated by endothelial, myocyte, and dendritic cell PD-L1, and by myeloid PD-1. The work will take advantage of newly developed mouse lines with lineage specific deficiencies of PD-L1 and PD-1, which will be used in the context of models of innate and adaptive immune mediated myocardial inflammation. These approaches will be organized into the following three Specific Aims: Aim 1. Determine which cell types mediate PD-L1-dependent protection against T cells in the heart, the mechanisms of protection, and the feasibility of therapeutically engaging these mechanisms. Aim 2. Test the hypothesis that the PD-1-PD-L1 pathway directly regulates myeloid cell inflammatory responses in the heart. Aim 3. Develop PD-1:PD-L1 dependent methods to therapeutically induced T cell tolerance to myocardial antigens The data generated by the completion of these Aims will define for the first time the regulation of cardiac inflammation by endothelial, myocyte, and DC PD-L1, and by myeloid PD-1. The findings will be important for development of therapeutic modalities to treat myocardial inflammation and for an understanding of the risks of therapeutic approaches to block PD-1 and PD-L1, which are actively being developed in cancer and chronic viral infection.