Mechanisms for intracranial aneurysm rupture

项目摘要 中性粒细胞和血小板在颅内动脉瘤病理生理学中的潜在作用已经很久了 临床观察提示。然而，中性粒细胞和血小板发挥作用的确切机制， 促进颅内动脉瘤破裂的机制尚不清楚。活化的中性粒细胞可以释放 用中性粒细胞酶如中性粒细胞弹性蛋白酶和髓过氧化物酶修饰的去致密DNA， 导致中性粒细胞胞外陷阱（NETs）的形成和中性粒细胞的死亡（NETosis）。 NET最初被描述为可以捕获和溶解病原体的结构。但最近的研究 提示NET在涉及血管炎症（包括动脉粥样硬化）的不育性疾病中的作用， 血管炎和静脉血栓形成。NET和血小板之间的相互作用可能导致恶性循环， NET形成和血小板活化，导致过度的血管壁损伤和血管扩张。 破裂我们的初步研究表明，NET存在于人类颅内动脉瘤和实验性颅内动脉瘤中。 小鼠动脉瘤此外，缺乏蛋白质精氨酸脱亚胺酶-4（PAD 4）的小鼠，PAD 4是一种蛋白质精氨酸脱亚胺酶所需的酶。 NET形成，破裂率降低。 我们假设NETs，中性粒细胞胞外陷阱，可以促进颅内肿瘤的发展， 动脉瘤破裂通过中性粒细胞和血小板活化的恶性循环。在目标1中，我们将检测中性粒细胞 与对照小鼠相比，PAD 4缺陷小鼠具有较低的破裂率并减少NET形成。在 目的2，我们将测试PAD 4抑制剂（Cl-脒）是否能在药理学上预防NET的形成 和GSK 484）或通过脱氧核糖核酸酶分解NET减少了溶酶体破裂。在目标3中，我们 测试血小板和嗜血小板-血小板相互作用是否有助于动脉瘤破裂。我们将测试 血小板减少的小鼠是否具有减少的NET形成和较低的破裂率。我们亦会研究 P-选择素或CD 11b/CD 18介导的嗜血小板-血小板相互作用对血小板聚集的作用 子宫破裂。 拟议的研究将为NET的作用及其与血小板的相互作用提供新的见解， 破裂的发展。这些结果将为未来开发新疗法的研究奠定基础， 靶向NET和血小板-中性粒细胞相互作用以预防囊性破裂。

Project Summary Potential roles of neutrophils and platelets in the pathophysiology of intracranial aneurysms have been long suggested by clinical observations. However, the exact mechanism by which neutrophils and platelets work to promote the rupture of intracranial aneurysms is not well understood. Activated neutrophils can release decondensed DNA decorated with neutrophil enzymes such as neutrophil elastase and myeloperoxidase, resulting in the formation of Neutrophil Extracellular Traps (NETs) and the death of neutrophils (NETosis). NETs were originally described as a structure that can trap and dissolve pathogens. However, recent studies suggest roles of NETs in sterile diseases that involve vascular inflammation including atherosclerosis, vasculitis, and venous thrombosis. Interactions between NETs and platelets may result in a vicious cycle of NET formation and platelet activation that leads to the excessive vascular wall damages and aneurysmal rupture. Our preliminary studies show that NETs exist in both human intracranial aneurysms and experimental mouse aneurysms. In addition, mice lacking protein arginine deiminases-4 (PAD4), an enzyme required for the NET formation, had a reduced rupture rate. We hypothesize that NETs, neutrophil extracellular traps, can promote the development of intracranial aneurysm rupture through the vicious cycle of neutrophil and platelet activation. In Aim 1, we will test neutrophil PAD4-deficient mice have a lower rupture rate and reduce NET formations compared to the control mice. In Aim 2, we will test whether the pharmacological prevention of NET formation by PAD4 inhibitors (Cl-amidine and GSK484) or the resolution of NETs by deoxyribonuclease reduces aneurysmal rupture. In Aim 3, we will test whether platelets and neutrophil-platelet interactions contribute to aneurysmal rupture. We will test whether thrombocytopenic mice have reduced NET formations and lower rupture rates. We will also study the contribution of P-selectin or CD11b/CD18-mediated neutrophil-platelet interactions to the development of aneurysmal rupture. The proposed studies will provide new insights into the roles of NETs and their interactions with platelets in the development of aneurysmal rupture. The results will be a basis for future studies to develop new therapies that target NETs and platelet-neutrophil interactions for the prevention of aneurysmal rupture.