Targeting the Inflammasome to Prevent Thoracic Aortic Aneurysms and Dissections

 描述（由申请人提供）：胸主动脉瘤和夹层（TAAD）是相关的心血管疾病，死亡率高。目前的药物治疗TAAD的方法是无效的，特别是在散发性疾病的患者不归因于遗传条件，如马凡氏综合征。尽管迫切需要开发新的治疗策略，但实现这一目标的主要障碍是对触发并促进散发性TAAD主动脉变性的分子机制的理解不足。因此，研究者的长期目标是提高对主动脉壁变性病理生物学的理解，以期开发新的药理学策略来预防TAAD的形成和进展。本申请的总体目标是确定NLRP 3炎性体级联反应（一种参与放大细胞内应激反应的多蛋白平台）在促进主动脉破坏中的作用，以及NLRP 3炎性体级联反应的程度。 该级联反应代表了抗TAAD的治疗靶点。中心假设是NLRP 3-ASC-半胱天冬酶-1级联通过刺激蛋白酶介导的细胞外基质（ECM）破坏和促进平滑肌细胞（SMC）收缩功能障碍来促进主动脉变性，并且该级联的药理学抑制将预防TAAD。这些假设将通过三个特定目的进行检验：（1）确定炎性体级联对胸主动脉壁结构和功能的影响，（2）确定级联如何促进蛋白酶活化和SMC收缩功能障碍，以及（3）确定级联的药理学抑制预防TAAD的程度。在第一个目标下，将进行使用敲除小鼠的实验以确定NLRP 3炎性体级联是否促进主动脉壁ECM破坏、收缩功能障碍和生物力学失效。在第二个目标下，将对主动脉SMC进行研究以确定级联是否通过直接切割两个特异性结构域来激活MMP-9。此外，将进行SMC的蛋白质相互作用、切割和收缩研究，以确定级联是否通过切割和降解肌球蛋白重链和原肌球蛋白促进SMC收缩功能障碍。在第三个目标下，将使用两种已建立的小鼠TAAD模型进行实验，以确定炎性小体激活的药理学抑制剂（例如格列本脲）是否会阻止TAAD的发展。这项研究意义重大，因为它将确定炎性小体级联反应如何促进TAAD的发展，以及炎性小体抑制剂可以预防TAAD的程度。这项研究是创新的，因为它代表了一个新的和实质性的偏离现状，即目前的药理学方法，以防止零星的TAAD进展。开发一种新的有效治疗方法将通过延迟或避免早期TAAD患者的侵入性手术、抑制不适合手术治疗的患者的疾病进展以及改善开放手术和血管内主动脉修复术的耐久性而产生重要的积极影响。

 DESCRIPTION (provided by applicant): Thoracic aortic aneurysms and dissections (TAAD) are interrelated cardiovascular diseases that carry high mortality. Current approaches to pharmacologic treatment of TAAD are ineffective, particularly in patients with sporadic disease not attributed to a genetic condition, such as Marfan syndrome. Although there is a critical need to develop new treatment strategies, a major barrier to this goal is a poor understanding of the molecular mechanisms that trigger and then promote aortic degeneration in sporadic TAAD. Therefore, the long-term goal of the investigators is to improve the understanding of the pathobiology of aortic wall degeneration in hope of developing new pharmacological strategies to prevent TAAD formation and progression. The overall objectives of this application are to determine the role of the NLRP3 inflammasome cascade, a multiprotein platform involved in amplifying intracellular stress responses, in promoting aortic destruction, and the extent to which this cascade represents a therapeutic target against TAAD. The central hypotheses are that the NLRP3-ASC- caspase-1 cascade promotes aortic degeneration by inciting protease-mediated extracellular matrix (ECM) destruction and promoting smooth muscle cell (SMC) contractile dysfunction, and that pharmacological inhibition of this cascade will prevent TAAD. These hypotheses will be tested through three specific aims: (1) Determine the effect of the inflammasome cascade on thoracic aortic wall structure and function, (2) Determine how the cascade promotes protease activation and SMC contractile dysfunction, and (3) Determine the extent to which pharmacological inhibition of the cascade prevents TAAD. Under the first aim, experiments using knockout mice will be conducted to determine whether the NLRP3 inflammasome cascade promotes aortic wall ECM destruction, contractile dysfunction and biomechanical failure. Under the second aim, studies with aortic SMCs will be performed to determine whether the cascade activates MMP-9 by directly cleaving two specific domains. In addition, protein interaction, cleavage, and contraction studies with SMCs will be conducted to determine whether the cascade promotes SMC contractile dysfunction by cleaving and degrading myosin heavy chain and tropomyosin. Under the third aim, experiments with two established mouse TAAD models will be conducted to determine whether pharmacological inhibitors of inflammasome activation (e.g. glyburide) will prevent TAAD development. The proposed research is significant because it will determine how the inflammasome cascade promotes TAAD development and the extent to which an inflammasome inhibitor can prevent TAAD. This research is innovative because it represents a new and substantive departure from the status quo, namely the current pharmacologic approaches to preventing sporadic TAAD progression. The development of a new, effective treatment would have an important positive impact by delaying or obviating invasive procedures in patients presenting with early-stage TAAD, suppressing disease progression in patients who are poor candidates for surgical treatment, and improving the durability of both open surgical and endovascular aortic repairs.