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。而当 全身性危险因素，如高脂血症，在病理下暴露于整个血管系统 在这种情况下，动脉粥样硬化斑块通常优先出现在血流受扰的部位，表明 血流动力在动脉粥样硬化形成中的作用。几十年来，内皮细胞(EC)对 壁面剪应力的变化即使不是唯一的，也是与流动动力学有关的主要焦点。 研究基本上认为循环中的血液是一种无细胞的液体，完全忽视了 机械力激活的血细胞对血管壁的影响。我们最近的研究原封不动地进行 微静脉显示血流的变化通过WSS和SS诱导的EC功能改变 红细胞释放三磷酸腺苷，红细胞通过膜联蛋白1(Panx1)通道释放三磷酸腺苷起关键作用 在改变欧盟壁垒完整性方面的作用。这一新奇的观察使我们假设RBC释放 血流变化过程中的三磷酸腺苷在部位特异性血管脆弱性和 协同作用促进血管炎症的发生和发展 动脉粥样硬化与局部WSS和全身危险因素。这一假设将得到检验。 在三个特定目标下的体内实验和计算，使用两个新建立的 血细胞特异性缺失Panx1(ApoE-/-Panx1-/-和AAV-)的高胆固醇血症小鼠模型 PCSK9DYPanx1-/-喂高脂饲料)。目的1是研究RBC释放的ATP在该部位的作用- 特异性内皮细胞对炎症的易感性；目标2是研究RBC释放的贡献 三磷酸腺苷对高胆固醇血症诱导的斑块形成和动脉粥样硬化进展的影响 大动脉。我们的初步数据显示，大约40-60%的动脉粥样硬化斑块在 RBC Panx1缺失的小鼠分支区，提示RBC释放的ATP在 血流紊乱引发血管发病机制。红细胞释放血中三磷酸腺苷的潜在作用 还将调查免疫细胞变化、血浆微粒和细胞因子水平。目标3是 利用高保真、三维、多尺度计算模型来预测悬浮物的分布 红细胞膜、应激诱导的三磷酸腺苷释放以及三磷酸腺苷在血管壁上的分布。 作为对AIMS 1和2中提出的活体研究的补充，拟议的计算研究将 首次区分了RBC应激和WSS在微观和宏观环境中的作用 不同血流条件下的循环，因此，对红细胞介导的血管的血流动力学的洞察 发病机制。拟议的研究对该领域的传统观点提出了挑战，并将提供更多 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，并帮助开发新的治疗方法。

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.