Endothelial exocytosis and the vascular dysfunction of aging

描述（由申请人提供）：老化内皮的特征是内皮扩张剂NO活性降低，ROS和氧化应激的产生增加，炎症和血栓活性增加。内皮储存颗粒，包括韦贝尔-帕拉体（WPBs）含有多种介质，在调节血管舒缩、血栓形成和炎症过程中发挥重要作用，并可通过刺激的胞吐作用迅速释放。这些内皮颗粒的胞吐和释放可能在与衰老相关的血管病理中起重要作用。然而，之前没有研究直接评估衰老对这一基本机制的影响。在新的初步结果中，我们证明老化血管的天然内皮在刺激胞吐过程中产生和释放病理生理介质（包括内皮素-1）的能力增加。我们的总体假设是，受刺激的胞吐增加内皮介质的释放和生成有助于衰老过程中的血管功能障碍。我们希望通过增加我们对衰老如何影响这一基本机制的理解，它可能为治疗与衰老相关的疾病提供新的方法。我们将使用Fischer大鼠衰老临床前模型来测试我们关于年轻和衰老血管的天然内皮的假设。本文提出了三个具体目标：目标1：确定衰老对内皮细胞内皮素-1生成和分泌的影响。这些实验将集中在评估老化内皮细胞在胞吐过程中产生内皮素-1 （ET-1）的能力增加。实验将探讨ET-1在年轻和衰老血管内皮的表达、加工和胞外释放。目的2：确定一氧化氮在调节老化血管内皮细胞外吐中的作用。本实验将探讨NO信号对衰老内皮细胞胞吐调节的抑制作用明显减弱。实验将集中于NO调控胞吐的机制。目的3：探讨内皮细胞外吐在衰老微循环中的病理作用。这些实验将评估内皮细胞胞吐失调在衰老中的潜在病理生理作用。这将通过研究胞吐在幼龄和老龄动物对肠系膜循环缺血再灌注微血管反应中的作用来实现。

DESCRIPTION (provided by applicant): The aging endothelium is characterized by reduced activity of the endothelial dilator NO, increased production of ROS and oxidant stress, and increased inflammatory and thrombotic activity. Endothelial storage granules, including Weibel-Palade Bodies (WPBs) contain numerous mediators that play important roles in regulating vasomotor, thrombotic and inflammatory processes, and can be rapidly released by stimulated exocytosis. It is likely that exocytosis and release of these endothelial granules play an important role in the vascular pathology associated with aging. However, no previous studies have directly assessed the effects of aging on this fundamental mechanism. In novel preliminary results, we demonstrate that native endothelium of aging blood vessels have increased ability to generate and release pathophysiological mediators (including endothelin-1) during stimulated exocytosis. Our overall hypothesis is that increased release and generation of endothelial mediators by stimulated exocytosis contributes to vascular dysfunction in aging. We hope that by increasing our understanding of how aging affects this fundamental mechanism, it may provide novel approaches to treat diseases associated with aging. We will test our hypotheses on native endothelium of young and aging blood vessels, using the Fischer rat preclinical model of aging. Three specific aims are proposed to: AIM 1: DETERMINE THE INFLUENCE OF AGING ON THE GENERATION AND EXOCYTOSIS OF ENDOTHELIN-1 FROM ENDOTHELIUM. These experiments will focus on evaluating the increased ability of aging endothelium to generate endothelin-1 (ET-1) during exocytosis. Experiments will investigate the expression, processing and exocytotic release of ET-1 from the endothelium of young and aging blood vessels. AIM 2: DETERMINE THE ROLE OF NITRIC OXIDE IN REGULATING ENDOTHELIAL WPB EXOCYTOSIS IN AGING BLOOD VESSELS. These experiments will investigate the apparent decreased inhibitory effect of NO signaling in regulating exocytosis in aging endothelium. Experiments will focus on the mechanisms underlying NO regulation of exocytosis. AIM 3: EVALUATE THE PATHOLOGICAL ROLE OF ENDOTHELIAL EXOCYTOSIS IN THE AGING MICROCIRCULATION. These experiments will evaluate the potential pathophysiological role of dysregulated endothelial exocytosis in aging. This will be achieved by investigating the role of exocytosis in the microvascular responses of young and aging animals to ischemia- reperfusion of the mesenteric circulation. PUBLIC HEALTH RELEVANCE: The Johns Hopkins physician and icon of modern medicine, Sir William Osler (1849-1919) commented that we are only as old as our arteries. We now know that we may only be as old as our endothelium. This project proposes to analyze the influence of aging on a fundamental mechanism of endothelial function (stimulated exocytosis), and to evaluate its role in stress- induced microvascular dysfunction associated with aging organs.