The Murine Dialysis Fistula Model Exhibits a Senescence Phenotype: Pathobiologic Mechanisms and Therapeutic Potential

血管通路功能障碍是终末期肾病及其医疗费用的主要发病率和死亡率的基础。 动静脉瘘(AVF)是首选的途径，因为它感染和血栓形成的风险较低， 以及它更强大的功能。然而，AVF的结果是严峻的，因为50%或更多的人可能永远不会成熟和 功能，而且越来越多的曾经起作用的AVF此后可能停止这样做。推广AVF 因此，成熟度和功能性是CKD和ESRD中一个主要的未得到满足的需求。在超过15年的时间里， Pi的实验室研究了AVF啮齿动物模型，并描述了血管病变和血管保护性物种 在AVF中。在过去的两年里，这个实验室寻找了适应不良反应范围的基础，并 观察到AVF表现出衰老表型，由多个生物标志物和驱动因素评估 衰老。这些发现，加上这个实验室公布的数据表明PAI-1显著上调， MCP-1、IL-6、MMPs等多种细胞因子的研究表明，AVF的衰老是提前诱导的。vbl.使用 本实验室引进的小鼠AVF-CKD模型，提出了三个目的：目的一：明确AvF-CKD的作用 启动AVF衰老和损害AVF结局的特定应激源。假设：AVF 施加血流动力学和其他从没有设计过的压力；这种压力会导致动静脉瘘 衰老。方法：这个目的是检查病理性剪应力和相对不平衡。 血管病变(例如，核因子-kB)超过血管保护性转录因子(如KLF2、KLF4和NRF2)；氧化应激； 尿毒症；以及与年龄相关的压力。目的II：明确p16INK4a和p21cip1表达细胞在动静脉瘘中的作用 衰老和动静脉动静脉瘘预后受损。假设：表达p16INK4a和p21cip1的细胞 促进衰老，删除衰老细胞(SCs)可改善AVF。方法：p16INK4a-表达 将使用INK-ATTAC小鼠删除AVF中的细胞，从而能够删除p16表达 SCS而不是非SCs；有条件的内皮特异性INK-ATTAC小鼠提供了一种额外的方法。这个 P21+/+和p21-/-小鼠以及p21-ER-CRE小鼠将检测表达p21cip1的干细胞的作用。 允许删除表达p21的干细胞。目标三：确定增龄剂、抗衰老药物的功效 衰老相关分泌表型(SASP)及其特异性SASP因子抑制物 改善AVF结果。假设：延缓衰老可以改善动静脉曲张的成熟和功能。 方法：干细胞存活是因为上调的抗细胞凋亡途径。诱导SC凋亡(感觉神经降解剂) 提供了一种新的治疗方法，SASP抑制药也是如此。这一目的是为了检验 衰老物质、SASP抑制剂和特定SASP因子的抑制剂(MCP-1和IL-6)在人类中上调 和啮齿动物Avf。总之，这个新的R01应用程序检查了AVF故障的一种新机制，即， 衰老；可能导致衰老的压力源；可能导致衰老的机制；以及 感觉剂治疗前沿的兴趣的一部分，后者现在进入临床试验。

Vascular access dysfunction underlies much of the morbidity and mortality in ESRD and its healthcare costs. The arteriovenous fistula (AVF) is the favored access because of its lower risk for infection and thrombosis, and its greater functionality. AVF outcomes, however, are grim as 50% or more may never mature and function, and increasing numbers of once functional AVFs may, thereafter, cease to do so. Promoting AVF maturation and functionality is thus a dominant unmet need in CKD and ESRD. For more than 15 years, the PI's laboratory has investigated AVF rodent models and delineated vasculopathic and vasoprotective species in the AVF. For the past 2 years, this laboratory sought the basis for the range of maladaptive responses and observed that the AVF exhibits a senescence phenotype as assessed by multiple biomarkers and drivers of senescence. These findings, along with this lab's published data demonstrating marked upregulation of PAI-1, MCP-1, IL-6, MMPs, and other mediators, indicate that senescence is prematurely induced in the AVF. Using the murine AVF-CKD model introduced by this laboratory, three aims are proposed: Aim I: Define the role of specific stressors in initiating AVF senescence and impairing AVF outcomes. Hypothesis: The AVF imposes hemodynamic and other stress which veins were never designed to bear; such stress causes AVF senescence. Approach: This aim examines pathologic shear stress and the relative imbalance of vasculopathic (eg, NF-kB) over vasoprotective (eg, Klf2, Klf4, and Nrf2) transcription factors; oxidative stress; uremia; and age-related stress. Aim II: Define the roles of p16Ink4a and p21cip1 expressing cells in AVF senescence and impairing AVF outcomes. Hypothesis: p16Ink4a-expressing and p21cip1-expressing cells drive senescence, and deletion of senescent cells (SCs) improves the AVF. Approach: p16Ink4a-expressing cells will be deleted in the AVF using the INK-ATTAC mouse which enables the removal of p16-expressing SCs but not non-SCs; a conditional endothelial-specific INK-ATTAC mouse provides an added approach. The role of p21cip1-expressing SCs will be examined using p21+/+ and p21-/- mice and p21-ER-Cre mice which enable deletion of p21-expressing SCs. Aim III: Define the efficacy of senolytics, inhibitors of senescence-associated secretory phenotype (SASP), and inhibitors of specific SASP factors in improving AVF outcomes. Hypothesis: Interrupting senescence improves AVF maturation and function. Approach: SCs survive because of upregulated anti-apoptotic pathways. Inducing SC apoptosis (senolytics) provides a novel therapeutic approach, as do SASP-inhibitory agents. This aim examines the efficacy of senolytics, SASP inhibitors, and inhibitors of specific SASP factors (MCP-1 and IL-6) upregulated in human and rodent AVFs. In sum, this new R01 application examines a novel mechanism of AVF failure, namely, senescence; stressors that may cause it; mechanisms that may drive it; and therapeutic approaches that are part of the groundswell of interest in the therapeutic frontier of senolytics, the latter now entering clinical trials.