EHD1-mediated Inflammation and Resolution in Atherosclerosis

项目总结/摘要 动脉粥样硬化性心血管疾病（CVD）是一种慢性脂蛋白驱动的炎症性疾病， 全球范围内的死因。传统的降脂治疗只能适度降低心血管风险， 由于“剩余风险”，人们认为这是由过度炎症引起的。新出现的证据显示 炎症消退的中断，一个活跃的组织修复过程，是一个关键机制， 有助于动脉粥样硬化斑块的进展。因此，鉴定介导这两种作用的新靶点， 炎症和消退对于开发心血管治疗策略至关重要， 解决和预防炎症。由于内吞运输是调节细胞内蛋白质水平的重要细胞过程， 巨噬细胞功能，我们集中在C-末端Eps 15同源结构域（EHD）的作用， 家族蛋白，巨噬细胞免疫应答中内吞运输的关键导体。可公开 人和鼠巨噬细胞群体的可用单细胞RNA测序（scRNA-seq）数据 动脉粥样硬化斑块显示EHD 1选择性表达于炎症病变巨噬细胞， 与其他EHD蛋白质相比，我们的新研究表明，EHD 1水平在病变中增加， 随着动脉粥样硬化的进展，人和鼠斑块中的巨噬细胞。这些数据支持一个 EHD 1的整体促动脉粥样硬化作用，并强调其与人类疾病的相关性。的总体目标 本研究旨在研究EHD 1在炎症反应中的作用及其机制， 动脉粥样硬化的背景。我们的数据表明，EHD 1通过诱导炎症反应， MerTK的胞外域裂解，MerTK是一种及时解决炎症所需的红细胞增多症受体， 通过促进巨噬细胞向促炎表型极化来抑制炎症。而且我们 建立了EHD 1和分拣蛋白之间的新联系，分拣蛋白是CVD的人类遗传风险因子，通过显示EHD 1 沉默降低分拣蛋白蛋白水平。MerTK的胞外域被金属蛋白酶切割 我们的初步数据显示，EHD 1增强细胞表面的ADAM 17， 会发生因此，我们将测试我们的假设，即EHD 1促进ADAM 17再循环到细胞表面， 导致MerTK裂解、缺陷性红细胞增多、炎症消退受损和斑块坏死（目的 1）。众所周知，自噬抑制促炎巨噬细胞的极化，我们发现， EHD 1抑制自噬，我们假设EHD 1促进促炎性巨噬细胞极化 通过抑制自噬，导致炎性斑块进展（Aim 2）。最后，我们将调查 EHD 1是否通过促进逆行转运稳定分拣蛋白并诱导炎性细胞因子分泌 （Aim 3）。通过探索EHD 1在动脉粥样硬化中的作用，我们希望将一个重要的 关于EHD 1介导的斑块进展中的细胞内运输的新概念，可以提供 新的治疗策略，以防止心血管疾病的基础。

Project Summary/Abstract Atherosclerotic cardiovascular disease (CVD), a chronic lipoprotein-driven inflammatory disorder, is the leading cause of death worldwide. Conventional lipid-lowering therapies only modestly lower cardiovascular risk in the population due to “residual risk,” thought to be caused by excessive inflammation. Emerging evidence shows that the interruption of inflammation resolution, an active tissue repair process, is a key mechanism that contributes to atherosclerotic plaque progression. Therefore, identifying novel targets that mediate both inflammation and resolution is crucial for developing cardiovascular therapeutic strategies that can both boost resolution and prevent inflammation. As endocytic trafficking is an essential cellular process that regulates macrophage function, we have focused on the role of C-terminal Eps15 homology domain-containing (EHD) family proteins, the key conductors of endocytic trafficking in the immune response of macrophages. The publicly available single-cell RNA sequencing (scRNA-seq) data of macrophage populations in both human and murine atherosclerotic plaques reveal that EHD1 is selectively expressed in inflammatory lesional macrophages compared with other EHD proteins, and our new study shows that EHD1 levels are increased in lesional macrophages from both human and murine plaques as atherosclerosis progresses. These data support an overall proatherogenic role for EHD1 and underscore its relevance to human disease. The overall objective of this proposal is to study the role and the underlying mechanisms of EHD1 in inflammation and resolution in the context of atherosclerosis. Our data suggest that EHD1 impairs inflammation resolution by inducing the ectodomain cleavage of MerTK, an efferocytosis receptor required for timely resolution of inflammation, and aids inflammation by promoting macrophage polarization toward a proinflammatory phenotype. Moreover, we have established a novel link between EHD1 and sortilin, a human genetic risk factor for CVD, by showing that EHD1 silencing decreases sortilin protein levels. The ectodomain of MerTK is cleaved by the metalloproteinase ADAM17, and our preliminary data show that EHD1 enhances ADAM17 on the cell surface, where shedding takes place. Hence, we will test our hypothesis that EHD1 promotes ADAM17 recycling to the cell surface, which leads to MerTK cleavage, defective efferocytosis, impaired inflammation resolution, and plaque necrosis (Aim 1). As autophagy is well known to suppress polarization of proinflammatory macrophages and we found that EHD1 suppresses autophagy, we hypothesize that EHD1 promotes proinflammatory macrophage polarization by suppressing autophagy, leading to inflammatory plaque progression (Aim 2). Finally, we will investigate whether EHD1 stabilizes sortilin and induces inflammatory cytokine secretion by facilitating retrograde transport of sortilin (Aim 3). By exploring the role of EHD1 in atherosclerosis, we hope to bring to the forefront an important new concept regarding EHD1-mediated intracellular trafficking in plaque progression, one that could provide the basis for novel therapeutic strategies to prevent CVD.