Molecular regulation of vein graft adaptation

描述（由申请人提供）：几种常见的人类疾病治疗方法的基石是手术使用静脉作为动脉导管。自体静脉旁路移植通常用于晚期心血管和外周血管疾病；同样，外科医生也会进行动静脉瘘（AVF），这是血液透析的首选途径。静脉移植物和AVF的不通畅，需要额外的重复手术和手术，反映了我们对静脉重塑的生物学理解的不完善，静脉重塑导致静脉成功适应动脉环境。这一知识缺口创造了一个未满足的医学需求，需要新的方法来增强静脉适应、成熟和静脉导管的成功长期使用。酪氨酸激酶受体eff - b4是胚胎静脉的决定因素。epf - b4表达的降低与人类和小鼠的静脉移植物适应有关，而epf - b4活性的降低对成年小鼠静脉移植物的静脉适应至关重要。我们提出了令人兴奋的新数据：1)我们的创新小鼠AVF模型忠实地再现了人类AVF的成熟，包括一个未成熟的子集；2)人和小鼠在AVF适应动脉环境过程中，epf - b4表达增加，而在静脉移植适应过程中，epf - b4表达降低；3) epf - b4功能对AVF的适应至关重要；4) Eph-B4酪氨酸-774是Eph-B4磷酸化和下游信号传导的关键位点。我们假设，静脉移植物适应导致血管身份的丧失，而AVF成熟导致动静脉身份的合并。我们的数据还提示了一种机制，例如，Eph-B4是一种以前未被认识但至关重要的血管血流动力学负荷内皮换能器。我们假设，静脉移植物和AVF血流动力学环境的差异对Eph-B4酪氨酸-774磷酸化和/或Eph-B4表达的调节存在差异。我们将结合体外和体内模型，使用生物反应器单独控制大小血管和内皮单层的血流动力学负荷，以及静脉移植物和AVF的体内模型，以验证我们的假设，具体目的如下：目的一：确定血流动力学负荷如何在全血管中差异调节Eph-B4磷酸化和功能，包括分析成功和失败的AVF。目的二：确定不同大小的剪切应力如何调节内皮细胞中epf - b4的磷酸化和功能。目的III：确定Eph-B4酪氨酸-774磷酸化如何调节静脉内皮细胞功能。这一工作建议将确立我们的创新性

DESCRIPTION (provided by applicant): A cornerstone of several common therapies for human diseases is the surgical use of a vein as an arterial conduit. Autologous vein bypass grafts are commonly performed for advanced cardiovascular and peripheral vascular disease; similarly, surgeons also perform arteriovenous fistulae (AVF), the preferred access for hemodialysis. The poor patency of both vein grafts and AVF, requiring additional re-do procedures and surgery, reflects our imperfect understanding of the biology of venous remodeling that leads to successful venous adaptation to the arterial environment. This knowledge gap creates an unmet medical need for novel approaches to enhance venous adaptation, maturation, and successful long-term use of venous conduits. The tyrosine kinase receptor Eph-B4 is an embryonic determinant of veins. Diminished Eph-B4 expression is associated with vein graft adaptation in humans and mice, and reduced Eph-B4 activity is essential for venous adaptation in adult mouse vein grafts. We present exciting new data that: 1) our innovative mouse model of AVF faithfully recapitulates human AVF maturation, including a subset that fail to mature; 2) in both humans and mice, Eph-B4 expression increases during AVF adaptation to the arterial environment, unlike the decreased Eph-B4 expression during vein graft adaptation; 3) Eph-B4 function is essential for AVF adaptation; and 4) Eph-B4 tyrosine-774 is a critical site of Eph-B4 phosphorylation and downstream signaling. We hypothesize that vein graft adaptation leads to loss of vessel identity and AVF maturation leads to merged arterial-venous identity. Our data also suggest a mechanism, e.g. that Eph-B4 is a previously unrecognized but critical endothelial transducer of hemodynamic loads to veins. We hypothesize that differences in the hemodynamic environments of vein grafts and AVF differentially regulate Eph-B4 tyrosine-774 phosphorylation and/or Eph-B4 expression. We will use a combination of in vitro and in vivo models, using a bioreactor that can individually control separate hemodynamic loads on both large and small vessels and endothelial monolayers, as well as using in vivo models of vein grafts and AVF, to test our hypothesis with the following specific aims: Aim I: Determine how hemodynamic loads differentially regulate Eph-B4 phosphorylation and function in whole vessels, including analysis of successful and failed AVF. Aim II: Determine how different magnitudes of shear stress regulate Eph-B4 phosphorylation and function in endothelial cells. Aim III: Determine how Eph-B4 tyrosine-774 phosphorylation regulates venous endothelial cell function. The work in this proposal will establish our innovative and paradigm-changing hypothesis that Eph-B4 is a novel and critical transducer of mechanical loads to the blood vessel and that Eph-B4 is differentially responsive to different types of loads, even in the absence of Ephrin-B2. Eph-B4 activity or lack thereof, defines the phenotype of the blood vessel and its function. Abnormal regulation of vessel identity during vein graft adaptation and AVF maturation can be manipulated to improve human clinical therapies.