Delineating the mechanisms underlying heart valve endothelial repair

项目摘要 主动脉瓣狭窄（VAS）约占所有先天性心脏病的3-6%，1如果左心室和右心室均存在瓣膜狭窄， 未经治疗可导致新生儿和幼儿的充血性心力衰竭。非侵入性，经皮 球囊瓣膜成形术（BVP）是儿科治疗的首选第一步，目的是推迟 决定性手术结果显示，虽然BVP显著降低了主动脉瓣（AoV）的峰值压差， 大多数患者在最初24小时内，经2-3年随访一半以上再狭窄而需 手术干预以修复或置换畸形和失效瓣膜。2，3因此，尽管BVP是有利的， 在一些患者中，其他患者被诊断为临床结果不佳，原因尚不清楚。 研究报告称，BVP可损伤甚至破裂AoV，4，5，家兔研究表明， 球囊膨胀特别损伤内皮。6，7此外，我们在小鼠中的工作强烈表明， 瓣膜内皮的直接损伤或靶向功能障碍导致结构退化和功能障碍， AoV受损，与人类组织学研究报告的内皮完整性差一致， 8 -11总的来说，这些研究表明，内皮损伤是一个显著的 瓣膜病理学的贡献者，这可能是BVP后VAS患者中观察到的不良结局的基础。 这就提出了一个问题：恢复内皮功能是否是治疗结构性心脏病的有效治疗策略？ 和易感个体的AoV功能恶化？为了探索这一点，我们开发了一种外科手术， AoV内皮损伤导致结构和功能恶化的小鼠模型。利用这个模型，我们 表明在对损伤的反应中，年轻健康的小鼠激活了有益的内在修复反应， 而这种反应在已知内皮功能障碍的衰老小鼠中受损。 此外，我们提出了一个机制，这些不同的反应。这一提议将检验 假设：受损瓣膜内皮细胞的有益内在修复反应需要TGF β 1-β 2。 Cthrc 1在瓣膜内皮细胞和下面的瓣膜间质细胞之间的信号传导，以促进增殖和 邻近未受损细胞的迁移，导致内皮修复。 为了验证这一点，我们提出了三个具体的目标：1）确定细胞和分子机制 参与AoV内皮损伤后的有益内在反应; 2）确定 内皮-TGF β 1用于受损AoV内皮的有益内在修复反应;和3）鉴定 AoV损伤后的有益内在修复反应的关键因子--补体Cthrc 1 内皮细胞成功完成将把内在修复性反应的创新机制界定为一个 AoV内皮损伤的结果，可应用于基于机械的化合物的治疗设计 促进内皮细胞的恢复，防止结构和功能的退化，特别是在易感的 个体

PROJECT ABSTRACT Valvular aortic stenosis (VAS) accounts for approximately 3-6% of all congenital heart defects,1 and if left untreated can lead to congestive heart failure in neonates and young infants. Non-invasive, percutaneous balloon valvuloplasty (BVP) is the preferred first step of treatment in pediatrics with the intent to postpone definitive surgery. Outcomes show that while BVP significantly reduces aortic valve (AoV) peak gradient within the first 24 hours in the majority of patients, by the 2-3 year follow up more than half re-stenose and require surgical intervention to repair or replace the dysmorphic and failing valve.2, 3 Therefore, while BVP is favorable in some patients, others are diagnosed with poor clinical outcomes and it is not clear why. Studies report that BVP can injure or even rupture the AoV,4, 5 and studies in rabbits have shown that balloon inflation specifically injures the endothelium.6, 7 Furthermore, our work in mice strongly suggests that direct injury to, or targeted dysfunction of the valve endothelium causes structural deterioration and functional impairment of the AoV, consistent with histological studies in humans reporting poor endothelial integrity in diseased valve tissue.8-11 Taken together, these studies suggest that endothelial damage is a significant contributor of valve pathology, and this may underlie poor outcomes observed in VAS patients following BVP. This raises the question: Can restoring endothelial function be an effective therapeutic strategy to treat structural and functional deterioration of the AoV in susceptible individuals? To explore this, we developed a surgical mouse model of AoV endothelial injury that causes structural and functional deterioration. Using this model, we show that in response to injury, young healthy mice activate a beneficial intrinsic reparative response that leads to endothelial restoration, while this response is impaired in aging mice with known endothelial dysfunction.12 In addition, we propose a mechanism underlying these diverse responses. This proposal will test the overall hypothesis that: The beneficial intrinsic reparative response of the injured valve endothelium requires Tgf1- Cthrc1 signaling between valve endothelial, and underlying valve interstitial cells to promote proliferation and migration of neighboring uninjured cells, leading to endothelial restoration. To test this, we propose three specific aims: 1) Determine the cellular and molecular mechanisms involved in the beneficial intrinsic response following AoV endothelial injury; 2) Determine the requirement of endothelial-Tgf1 for the beneficial intrinsic reparative response of the injured AoV endothelium; and 3) Identify interstitial-Cthrc1 as a critical factor for the beneficial intrinsic reparative response of the injured AoV endothelium. Successful completion will define innovative mechanisms of the intrinsic reparative response as a result of AoV endothelial injury that can be applied to the therapeutic design of mechanistic-based compounds to promote endothelial restoration and prevent structural and functional deterioration, particularly in susceptible individuals.