Red blood cell released ATP in disturbed blood flow-initiated site specific vascular inflammation and atherosclerosis

血管炎症和动脉粥样硬化与许多心血管疾病有关。而 全身性危险因素如高脂血症在病理条件下暴露于整个脉管系统， 动脉粥样硬化斑块通常优先在血流紊乱的部位发展，表明 血液动力学在动脉粥样硬化形成中的作用。几十年来，内皮细胞（EC）对 壁面切应力（WSS）的变化一直是流动动力学研究的主要（如果不是唯一的）焦点 研究，基本上认为循环血液是无细胞的液体，完全忽略了 机械力激活的血细胞对血管壁的影响。我们最近的研究在完整的 微静脉表明，血流的变化通过WSS和SS诱导的 红细胞释放ATP，红细胞通过泛连接蛋白1（Panx 1）通道释放ATP， 改变EC屏障完整性的作用。这一新的观察使我们假设，RBC释放 血流变化期间的ATP在部位特异性血管脆弱性中起重要作用， 协同促进血管炎症的发生和发展， 动脉粥样硬化沿着局部WSS和全身危险因素。这一假设将得到检验 实验在体内和计算在三个特定的目标下，使用两个新建立的 血细胞特异性缺失Panx 1的高胆固醇血症小鼠模型（ApoE-/-Panx 1-/-和AAV- PCSK 9DYPanx 1-/-用高脂肪饮食喂养）。目的1探讨红细胞释放ATP在红细胞凋亡中的作用。 特异性内皮细胞对炎症的脆弱性;目的2是研究释放的RBC的贡献 ATP对高胆固醇血症诱导的位点特异性斑块形成和动脉粥样硬化进展 大动脉我们的初步数据显示，在1000 - 2000 ℃时， 红细胞Panx 1缺失小鼠的分支区域，表明红细胞释放ATP在 血流紊乱引发的血管发病机制。红细胞释放ATP在血液中的潜在作用 还将研究免疫细胞改变、血浆微粒和细胞因子水平。目标3是 利用高保真度，三维，多尺度计算模型来预测SS在 红细胞膜，应激诱导的ATP释放，以及ATP在血管壁的分布。 作为对目标1和2中提出的体内研究的补充，提出的计算研究将 提供，第一次，RBC应力和WSS在微观和宏观两方面的作用之间的区别， 在不同的流动条件下循环，因此，血液动力学的见解RBC介导的血管 发病机制这项研究对该领域的传统观点提出了挑战， 局部血流动力学和全身环境因素的综合表征 血管发病机制，并有助于开发新的治疗方法。

Vascular inflammation and atherosclerosis are implicated in many cardiovascular diseases. While the systemic risk factors such as hyperlipidemia are exposed to entire vasculature under pathological conditions, the atherosclerotic plaques often preferentially develop at sites with disturbed flow, indicating a role of hemodynamic forces in atherogenesis. For decades, endothelial cell (EC) responses to the changes in wall shear stress (WSS) have been the main, if not sole, focus of the flow dynamics related studies, which basically consider the circulating blood as a cell-free fluid and completely overlooked the impact of mechanical force-activated blood cells on the vascular walls. Our recent study conducted in intact venules showed that changes in blood flow alter EC function through both WSS and the SS-induced release of ATP from RBCs, and the RBC released ATP through a pannexin 1 (Panx1) channel plays a key role in altering EC barrier integrity. This novel observation led us to hypothesize that the RBC-released ATP during blood flow changes plays a significant role in site-specific vascular vulnerability and synergistically contributes to the initiation and progression of vascular inflammation and atherosclerosis along with local WSS and systemic risk factors. This hypothesis will be tested experimentally in vivo and computationally in silico under three specific aims using two newly established hypercholesterolemia mouse models with blood cell specific deletion of Panx1 (ApoE-/-Panx1-/- and AAV- PCSK9DYPanx1-/- fed with high fat diet). Aim 1 is to investigate the role of RBC-released ATP in the site- specific endothelium vulnerability to inflammation; Aim 2 is to investigate the contribution of RBC released ATP to hypercholesterolemia-induced site-specific plaque formation and atherosclerosis progression in major arteries. Our preliminary data showed about 40-60% reduction of aorta atherosclerotic plaque at branch regions in mouse with RBC Panx1 deletion, suggesting an important role of RBC released ATP in disturbed blood flow-initiated vascular pathogenesis. The potential roles of RBC released ATP in blood immune cell alterations, plasma microparticles and cytokine levels will also be investigated. Aim 3 is to utilize a high-fidelity, three-dimensional, multiscale computational model to predict the distribution of SS on the RBC membrane, the stress-induced ATP release, and the distribution of ATP at the vascular walls. Complementing the in vivo studies proposed in Aims 1 and 2, the proposed computational studies will provide, for the first time, a distinction between the roles of RBC stress and WSS in both micro and macro- circulation under diverse flow conditions, and hence, hemodynamic insights into RBC-mediated vascular pathogenesis. The proposed study challenges the conventional views in the field and will provide a more comprehensive characterization of local hemodynamic and systemic environmental factors responsible for vascular pathogenesis and aid the development of novel therapeutics.