Hemodynamics, Uremia & Vascular Biology: Interactive Pathways for AVF Maturation

虽然动静脉内瘘（AVF）被广泛认为是最好的透析血管通路形式， 他们目前有非常严重的问题与成熟失败，这是一个无法实现充分的 静脉扩张和流动以支持透析。在放射学水平，AVF成熟失败的特征是： 吻合口周围静脉段狭窄，而在组织学和发病水平上， 新生内膜增生和缺乏外向重塑的组合。在机械层面上， 我们在当前资助期内进行的研究清楚地表明， 导致非常不同的临床（流量和直径）和组织学终点。因此我们认为 血流动力学损伤是关键的上游事件，然后导致下游级联事件（ 血管生物学对损伤的反应）。然而，一个重要的未知因素仍然是尿毒症的潜在影响 在这个级联中，特别是在能够调节下游生物反应的背景下， 上游血流动力学损伤。尿毒症的病因是什么？尿毒症是什么？ 氧化应激、炎症和内皮功能障碍显著增加，所有这些都是关键因素 在下游的生物反应血流动力学损伤。此外，我们和其他人已经能够 证明透析时采集的静脉组织样本中存在新生内膜增生 血管通路的建立（甚至在暴露于血流动力学变化之前）表明尿毒症本身（ 它与炎症、氧化应激和内皮功能障碍的联系），可能是一个重要的独立 静脉狭窄/重塑的风险因素。 因此，当前建议的中心假设是AVF成熟是相互作用的最终结果 在两种主要的机械途径（上游血流动力学损伤和尿毒症）之间存在广泛的差异， 影响下游血管生物学）。换句话说，我们想探索的是， 尿毒症调节对血液动力学损伤的生物反应。我们计划解决这个中心假设 三个具体目标。 在具体目标1中，我们将扩展以下假设： 与直AVF相比）启动一系列差异生物学（基因表达和细胞表型） 这导致不同的形态测量（壁厚）和临床（流量和直径）终点。 该特定目标还将为特定目标2中的研究提供历史同期比较。 在具体目标2中，我们将讨论尿毒症本身可以影响/调节生物学特性的假设。 反应的血流动力学损伤，通过详细比较的生物学，形态学和临床 与对照动物相比，在尿毒症猪模型背景下的具体目标1中描述的终点 (from具体目标1）。 最后，在具体目标3中，我们将联合收割机结合下一代测序技术（RNA Seq. 分析）与我们独特的尿毒症动物模型，以展望未来，关于鉴定 新的基因、途径和机制。然后，这些信息可以用于识别新的预测 AVF成熟的标志物，或者作为未来生物学发展的知识基础， 预防或治疗AVF成熟失败的相关疗法。 总之，我们认为这一建议是重要的，因为它侧重于一个重要的临床问题， 目前还没有有效的治疗方法;它的独特之处在于它解决了以下复杂问题： 尿毒症本身作为AVF成熟的调节剂，最后，它是创新的，因为它将先进的测序 技术和生物信息学应用于临床相关尿毒症模型。

Although arteriovenous fistulae (AVFs) are widely considered to be the best form of dialysis vascular access they currently have very significant problems with maturation failure, which is an inability to achieve adequate venous dilatation and flow to support dialysis. At a radiological level AVF maturation failure is characterized by a perianastomotic venous segment stenosis, while at a histological and pathogenetic level it is due to a combination of neointimal hyperplasia and an absence of outward remodeling. At a mechanistic level, work performed by us during the current grant period has clearly demonstrated that differing hemodynamic profiles result in very different clinical (flow and diameter) and histological end points. We therefore believe that hemodynamic injury is the critical upstream event, which then results in a downstream cascade of events (the vascular biology response to injury). An important unknown, however, remains the potential impact of uremia within this cascade, especially in the context of being able to modulate the downstream biological response to upstream hemodynamic injury. The reason that uremia is likely to be important is that it is characterized by significant increases in oxidative stress, inflammation and endothelial dysfunction, all of which are key players in the downstream biological response to hemodynamic injury. In addition we, and others have been able to demonstrate the presence of neointimal hyperplasia within venous tissue samples taken at the time of dialysis vascular access creation (even before exposure to hemodynamic changes) suggesting that uremia per se (with its linkages to inflammation, oxidative stress and endothelial dysfunction), could be an important independent risk factor for venous stenosis/remodeling. The central hypothesis of the current proposal therefore is that AVF maturation is the end result of interactions between a wide spectrum of two prominent mechanistic pathways (upstream hemodynamic injury and uremia influenced downstream vascular biology). Put another way we want to explore how the presence or absence of uremia modulates the biological response to hemodynamic injury. We plan to address this central hypothesis through three Specific Aims. In Specific Aim 1, we will expand on the hypothesis that differential hemodynamic shear stress profiles (curved versus straight AVFs) initiate a sequence of differential biological (gene expression and cellular phenotyping) profiles, which then result in different morphometric (wall thickness) and clinical (flow and diameter) end points. This Specific Aim will also provide a historically concurrent comparator for the studies in Specific Aim 2. In Specific Aim 2, we will address the hypothesis that uremia per se can influence/modulate the biological response to hemodynamic injury, through a detailed comparison of the biological, morphometric and clinical end points described in Specific Aim 1 in the setting of a uremic pig model as compared to control animals (from Specific Aim 1). Finally in Specific Aim 3, we will combine the power of next generation sequencing technology (RNA Seq. analyses) with our unique animal model of uremia in order to look to the future, with regard to the identification of novel genes, pathways and mechanisms. This information could then be used to identify novel predictive markers for AVF maturation, or alternatively, as a knowledge base for the development of future biologically relevant therapies to prevent or treat AVF maturation failure. In summary, we believe that this proposal is significant because it focuses on an important clinical problem for which there are currently no effective therapies; it is unique in that it addresses head on the complex issue of uremia per se as a modulator of AVF maturation, and finally it is innovative in that it links advanced sequencing technology and bioinformatics to a clinically relevant uremic model.