EHD1-mediated Inflammation and Resolution in Atherosclerosis

项目摘要/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，是 全球范围内的死因。传统的降脂疗法仅略微降低了老年人的心血管风险 人群由于“残留风险”，被认为是过度炎症所致。新出现的证据表明 炎症分解的中断是一种活跃的组织修复过程，是 有助于动脉粥样硬化斑块的发展。因此，确定新的目标既能调解 炎症和消退是开发心血管治疗策略的关键，这种治疗策略既可以促进 消解和预防炎症。因为胞内转运是调节 巨噬细胞的功能，我们已经集中在C-末端Eps15同源结构域包含(EHD)的作用 家族蛋白，巨噬细胞免疫反应中胞内运输的关键导体。公开的 人和小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EHD1在炎性病变巨噬细胞中选择性表达 与其他EHD蛋白相比，我们的新研究表明，EHD1水平在皮损中升高 随着动脉粥样硬化的进展，来自人类和小鼠斑块的巨噬细胞。这些数据支持 EHD1的总体致动脉粥样硬化作用，并强调其与人类疾病的相关性。总的目标是 本研究旨在研究EHD1在炎症反应和消退中的作用及其机制。 动脉粥样硬化的背景。我们的数据表明，EHD1通过诱导 MerTK的胞外结构域裂解，MerTK是一种及时消退炎症所需的胞吐受体，以及艾滋病 通过促进巨噬细胞极化向致炎表型转变而引起的炎症。此外，我们有 在EHD1和山梨素之间建立了一种新的联系，山梨素是一种人类患心血管疾病的遗传风险因素，通过证明EHD1 沉默会降低山梨素的蛋白质水平。MerTK的胞外结构域被金属蛋白酶切割 ADAM17，我们的初步数据显示，EHD1增强了细胞表面的ADAM17，在那里脱落 发生了。因此，我们将检验我们的假设，即EHD1促进ADAM17循环到细胞表面，这 导致MerTK裂解、有缺陷的气泡吞噬、炎症分解受损和斑块坏死(AIM 1)。众所周知，自噬可以抑制促炎巨噬细胞的极化，我们发现 EHD1抑制自噬，我们假设EHD1促进促炎巨噬细胞极化 通过抑制自噬，导致炎症斑块进展(目标2)。最后，我们将调查 EHD1是否通过促进逆行转运稳定山梨素和诱导炎性细胞因子分泌 山梨素(目标3)。通过探索EHD1在动脉粥样硬化中的作用，我们希望将一个重要的 关于EHD1介导的斑块进展中的细胞内运输的新概念，一个可能提供 为预防心血管疾病的新治疗策略奠定了基础。

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.