Molecular regulation of fistula adaptation for dialysis access

透析通路瘘管适应的分子调控

• 批准号: 8634237
• 负责人: Alan Dardik
• 金额: --
• 依托单位: VA CONNECTICUT HEALTHCARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8634237
• 关键词: Adult; American; Animal Model; Arteries; Arteriovenous fistula; Biology; Blood Circulation; Blood Vessels; Caliber; Caring; Catheters; Cell Proliferation; Cell physiology; Cells; Characteristics; Clinical; Clinical Trials; Data; Development; Dialysis procedure; Embryo; End stage renal failure; Endothelial Cells; Environment; Ephrin-B2; Ephrins; Excess Mortality; Exhibits; Fistula; Genes; Government; Healthcare Systems; Hemodialysis; Human; In Vitro; Incidence; Lead; Legal patent; Length; Ligands; Ligation; Mediating; Mediator of activation protein; Medical; Modeling; Molecular; Molecular Models; Morbidity - disease rate; Mus; Mutate; Operative Surgical Procedures; Pathway interactions; Patients; Phosphorylation; Play; Procedures; Regulation; Renal Replacement Therapy; Resistance; Rest; Role; Second Look Surgery; Signal Transduction; Smooth Muscle Myocytes; Specific qualifier value; Specimen; Surgeon; System; Testing; Therapeutic Intervention; Thick; Time; Tyrosine; United States; Veins; Venous; Veterans; base; cell motility; cost; improved; inhibitor/antagonist; innovation; member; molecular modeling; mortality; neointima formation; novel strategies; prevent; public health relevance; receptor; shear stress

End-stage renal disease (ESRD) upsets the lives of over half a million people in the United States, with an incidence of over 100,000 new cases per year and a mortality rate of approximately 88,000 people each year. The Veteran's Affairs cares for approximately 30,000 veterans with ESRD. The costs to treat ESRD, approximately $39 billion in 2008, continue to grow. The most common option chosen for renal replacement therapy is hemodialysis; access for hemodialysis is performed by either arteriovenous fistula (AVF), arteriovenous graft (AVG), or temporary catheter placement. Although fistulae take time to "mature," e.g. dilate, thicken and increase flow, prior to beginning dialysis, AVF continue to be the preferred mode of access, with superior long term results compared to AVG and catheter access. Despite the superiority of AVF access compared to its alternatives, AVF are still far from perfect. AVF fail to mature in approximately 20-50% of cases, with many of these AVF requiring some therapeutic intervention to mature successfully. In fact, these poor clinical results demonstrate that AVF defy all the rules of vascular surgery; despite their desirable characteristics of short length, large diameter, high flow, and low resistance runoff, AVF exhibit the worst patency of any procedure performed by vascular surgeons. The poor patency of AVF clearly reflects our imperfect understanding of the biology of venous remodeling leading to AVF maturation and the unmet medical need for novel approaches to enhance AVF maturation and subsequent fistula usage. Several members of the Ephrin-Eph pathway have recently been described as developmentally specified critical determinants of vessel identity, with Ephrin-B2 ligand an embryonic determinant of arteries and Eph-B4 receptor an embryonic determinant of veins. However, it is currently not established whether Eph- B4 is functional in adult veins, and whether the Ephrin-Eph pathway plays a mechanistic role during AVF adaptation to the arterial environment. We hypothesize that increased Eph-B4 expression and/or activation (as assessed by phosphorylation) mediates increased AVF wall diameter and thickening during normal AVF maturation. This is a different mechanism than by which Eph-B4 mediates vein graft adaptation. We will test our hypothesis with these aims: Aim I: To determine whether Eph-B4 mediates diameter expansion and/or wall thickening during normal AVF maturation. Our hypothesis, based on our preliminary data, is that increased expression and/or activation of the venous specification gene Eph-B4 leads to normal AVF diameter expansion and wall thickening and fistula maturation. We will examine surgical specimens derived from patent human AVF undergoing surgical revision or ligation to determine how AVF diameter and/or wall thickness correlate with Eph-B4 expression and activation. We will test this hypothesis by directly increasing and decreasing Eph-B4 signaling in our mouse AVF model and correlating vessel identity with AVF diameter and wall thickness. Aim II: To determine how shear stress regulates Eph-B4 phosphorylation and expression. Our hypothesis is that shear stress promotes AVF maturation by stimulating Eph-B4 signaling and expression in endothelial cells; in this way, changes in shear stress lead to AVF dilation and wall thickening. We will test this hypothesis by altering shear stress in our in vitro flow models, using both whole vein and endothelial cell flow models, and show that arterial magnitudes of shear stress stimulate Eph-B4 phosphorylation and expression. Aim III: To determine how Eph-B4 signaling regulates vascular cell function. Our hypothesis is that Eph- B4 phosphorylation on tyrosine-774 is a critical regulator of Eph-B4 downstream function in vascular cells. We will test this hypothesis by examining the differential effects of wild type and mutated Eph-B4 on endothelial and smooth muscle cell signal transduction as well as cell proliferation and migration.

末期肾脏疾病（ESRD）使美国超过50万人的生命感到不安 每年超过100,000例新病例的发病率，死亡率约为88,000人 年。这位退伍军人的事务照顾大约30,000名退伍军人。治疗ESRD的费用， 2008年约有390亿美元，继续增长。选择用于肾脏替代的最常见选择 治疗是血液透析；血液透析的访问是通过静脉瘘（AVF）进行的 动脉移植（AVG）或临时导管放置。尽管瘘管需要时间才能“成熟”，例如 在开始透析之前，扩张，增厚和增加流量，AVF继续是首选的访问方式， 与AVG和导管接入相比，长期结果优越。尽管AVF访问很高 与替代方案相比，AVF仍然远非完美。 AVF在大约20-50％中无法成熟 案例，其中许多AVF需要一些治疗性干预才能成功成熟。实际上，这些 不良的临床结果表明，AVF违背了所有血管手术规则。尽管他们是理想的 短长度，大直径，高流量和低电阻径流的特征，AVF表现出最差的 血管外科医生执行的任何手术的通畅性。 AVF的糟糕通畅显然反映了我们的 对静脉重塑的生物学的理解不完善，导致AVF成熟和未经完成的医学 需要新颖的方法来增强AVF成熟和随后的瘘管使用情况。 埃弗林 - 途径的几个成员最近被描述为发展 血管身份的特定临界决定因素，ephrin-b2配体是动脉的胚胎决定因素 EPH-B4受体是静脉的胚胎决定因素。但是，目前尚未确定EPH- B4在成年静脉中起作用，以及在AVF期间ephrin-eph途径是否起机械作用 适应动脉环境。 我们假设增加EPH-B4表达和/或激活（通过磷酸化评估） 在正常的AVF成熟过程中介导AVF壁直径增加并增厚。这是不同的 机制比EPH-B4介导静脉移植的适应性。我们将以这些目的检验我们的假设： 目的I：确定EPH-B4是否介导直径膨胀和/或壁增厚 正常的AVF成熟。我们的假设基于我们的初步数据，是增加表达和/或 静脉规范基因EPH-B4的激活导致正常的AVF直径膨胀和壁 增厚和瘘管成熟。我们将检查来自专利人AVF的手术标本 进行手术修订或结扎，以确定AVF直径和/或壁厚的厚度与 EPH-B4表达和激活。我们将通过直接增加和减少EPH-B4来检验这一假设 我们的小鼠AVF模型中的信号传导，并将血管身份与AVF直径和壁厚相关。 AIM II：确定剪切应力如何调节EPH-B4磷酸化和表达。我们的 假设是剪切应力通过刺激EPH-B4信号传导和表达来促进AVF的成熟 内皮细胞；这样，剪切应力的变化会导致AVF扩张和壁增厚。我们将测试这个 通过使用整个静脉和内皮细胞流量，通过改变体外流量模型中的剪切应力来假设 模型，并表明剪切应力的动脉大小刺激EPH-B4磷酸化和表达。 AIM III：确定EPH-B4信号如何调节血管细胞功能。我们的假设是 酪氨酸-774上的B4磷酸化是血管细胞中EPH-B4下游功能的关键调节剂。我们 将通过检查野生型和突变的EPH-B4对内皮的差异作用来检验这一假设 和平滑肌细胞信号转导以及细胞增殖和迁移。