Impact of dyslipidemia on endothelial biomechanics

摘要： 内皮生物力学在多种内皮功能中发挥着重要作用。我们 研究集中在氧化脂质对内皮生物力学的调节，我们发现氧化脂质诱导内皮细胞的生长， 显著的内皮硬化。我们的长期目标是阐明 血脂异常诱导的内皮生物力学变化，并确定这些变化的贡献， 内皮功能障碍的机制。在本次资助期间，我们提供了 对血脂异常诱导的主动脉内皮细胞（EC）硬化的重要机制见解显示 它主要依赖于CD 36清道夫受体和RhoA/ROCK级联的激活。我们也 发现oxLDL/血脂异常和促动脉粥样硬化的血流紊乱（DF）环境具有协同作用， 在体外和体内诱导EC硬化的作用。在目前的建议中，我们将这些研究扩展到 提出了三个新的目标：在目标1中，我们致力于进一步阐明oxLDL诱导EC的机制 硬化首先（目的1A），我们将确定CD 36在EC硬化中的作用是否是提供途径， 氧化低密度脂蛋白的内在化，随后氧化脂质进入膜，或者 需要CD 36来诱导导致EC硬化的信号级联。我们还将确定 已知与CD 36结合的脂肪酸对EC硬度的影响。在目标的第二部分（1B）中，我们将 研究CD 36介导的oxLDL摄取和RhoA激活之间的机制联系 级联，这是基于我们的初步数据，我们建议通过RhoA从 抑制调节剂GDI-1。在目标2中，我们关注oxLDL/DF诱导的EC硬化在 破坏内皮屏障和内皮-单核细胞粘附（目的2B）。第一（目标2A），我们 建议深入研究oxLDL和DF对激活 RhoA/ROCK级联反应，并区分RhoA依赖性EC硬化与 细胞凋亡在EC屏障的破坏。在目标的第二部分（2B）中，我们研究了 oxLDL诱导的EC硬化在单核细胞粘附中通过区分EC硬化的影响 vs. oxLDL诱导的炎症性NF κ B级联反应的激活和 内皮粘附分子。在目标3中，这些研究被扩展到研究 血脂异常诱导的体内内皮硬化及其在动脉粥样硬化形成中的作用 病变这一目标将使用两种内皮特异性CD 36缺陷小鼠模型实现，一种是Ti 2 e- 驱动的模型，其是出生时CD 36缺陷型和Vecad驱动的诱导型模型。两款车型都将 在两种主要的小鼠血脂异常模型ApoE-/-和LDLR-/-的背景下进行测试。综合起来看， 这些新的研究有望为我们对内皮细胞的理解提供重要的新见解， 血脂异常条件下的生物力学特性，特别是在促动脉粥样硬化血流动力学中 环境

Abstract: Endothelial biomechanics is increasingly recognized to play a key role in multiple endothelial functions. Our studies focus on regulation of endothelial biomechanics by oxidized lipids, which we showed to induce significant endothelial stiffening. Our long term goal is to elucidate the mechanisms responsible for dyslipidemia-induced changes in endothelial biomechanics and to determine the contribution of these mechanisms to endothelial dysfunction. During the current funding period of this grant, we provided significant mechanistic insights into dyslipidemia-induced stiffening of aortic endothelial cells (EC) showing that it critically depends on CD36 scavenger receptor and activation of RhoA/ROCK cascade. We also discovered that oxLDL/dyslipidemia and pro-atherogenic disturbed flow (DF) environment have a synergistic effect in inducing EC stiffening in vitro and in vivo. In the current proposal, we extend these studies to address three new goals: In Aim 1, we focus on elucidating further the mechanism of oxLDL-induced EC stiffening. First (aim 1A), we will determine whether the role of CD36 in EC stiffening is to provide the route for oxLDL internalization with subsequent incorporation of oxidized lipids into the membrane or whether CD36 is required to induce a signaling cascade that leads to EC stiffening. We will also determine the impact of fatty acids known to bind to CD36 on EC stiffness. In the second part of the aim (1B), we will investigate the mechanistic link between CD36 mediated oxLDL uptake and activation of the RhoA cascade, which based on our preliminary data, we propose to be mediated by the dissociation of RhoA from the inhibitory regulator GDI-1. In Aim 2, we focus on the role of oxLDL/DF-induced EC stiffening in the disruption of the endothelial barrier and endothelial-monocyte adhesion (aim 2B). First (aim 2A), we are proposing to investigate in depth the synergistic impact of oxLDL and DF on the activation of the RhoA/ROCK cascade and to discriminate between the contributions of RhoA-dependent EC stiffening vs. apoptosis in the disruption of the EC barrier. In the second part of the aim (2B), we investigate the role of oxLDL-induced EC stiffening in monocyte adhesion by discriminating between the impacts of EC stiffening vs. oxLDL-induced activation of the inflammatory NFkB cascade and increase in the expression of endothelial adhesion molecules. In Aim 3, these studies are extended to investigate the mechanism of dyslipidemia-induced endothelial stiffening in vivo and its contribution to the formation of atherosclerotic lesions. This goal will be achieved using two models of endothelial-specific CD36-deficient mice, a Ti2e- driven model, which is CD36-deficient from birth and VEcad-driven inducible model. Both models will be tested on the backgrounds of two major models of mouse dyslipidemia, ApoE-/- and LDLR-/-. Taken together, these new studies are expected to provide significant new insights into our understanding of endothelial biomechanical properties under dyslipidemic conditions particularly in pro-atherogenic hemodynamic environment.