The Role of Endothelin-1 in Tubular Injury in Sickle Cell Disease

1.项目摘要/摘要 指导阶段：镰状细胞病(SCD)是美国最常见的血红蛋白病，与 3终末期肾功能衰竭的高发年龄在中位年龄23岁。由于缺乏肾脏靶向 4治疗后中位生存期<3年。SCD环境诱导ET-1及ET-1升高 5、SCD患者血清白蛋白水平与微量白蛋白尿相关。我最近证明了两种ET受体A(ETA) 6-羟色胺和双重ET受体A和B(ETAB)拮抗剂可阻止肾小球对白蛋白通透性的增加 7在SCD小鼠模型中，但只有ETA受体拮抗剂能阻止蛋白尿。这些发现让我 8支持ET-1通过激活ETA受体参与SCD小鼠肾损伤的假说，而ETB通过ETA受体激活促进SCD小鼠肾损伤 9受体提供肾小管保护作用。因此，指导阶段的中心假设是在SCD中 10小时环境、ET-1升高和ETA受体活性增加介导肾小管功能障碍导致 11在SCD小鼠肾小管损伤，这与ETB活性相反。被辅导者的具体目标1 12时相将确定ET-1和ETA受体活性增加是否通过减少介导肾小管损伤 13探讨SCD小鼠肾小管白蛋白摄取机制及ETB受体拮抗剂是否加重ET-1对肾小管白蛋白摄取的影响 14.管状白蛋白处理。随着体内成像技术的新培训的使用，我将跟踪荧光- 15个标记白蛋白评估治疗SCD和治疗的载体或ET受体拮抗剂的管状白蛋白重吸收 16只基因对照小鼠。我们还将确定ET-1和ET受体对近端小管的直接作用 17个白蛋白转运体在体外和体内设置。独立阶段：此阶段将侧重于 18在先前培训的基础上，探索肾铁处理机制的独立调查路线。 19.有证据表明，SCD中铁沉积增加与蛋白尿有关，这两者都可能是 20被ETA受体阻断剂减弱。尽管ET-1参与了SCD的肾小球病变，但其相关性 21铁诱导的毒性和由此导致的肾小管损伤尚不清楚。因此，总体假设是， 22其独立阶段是ET-1升高导致肾小管铁处理功能障碍，铁超载，以及 23例肾小管损伤为SCD。这将通过培养的近端小管细胞和 24次在SCD小鼠体内注射。具体目标2将确定SCD中管状铁处理受损是否会导致铁 25年ET-1超负荷导致近端小管铁摄取增加和/或近端小管铁摄取减少 26.拆除。具体目标3将确定导致SCD肾小管损伤的铁毒机制。这 将通过确定肾脏铁超载是否通过氧化应激和/或导致肾小管损伤来进行测试 28例SCD肾病患者线粒体功能障碍。拟议研究的目标无疑将阐明 29关于参与肾小管损伤的发生和发展的新的机制途径，一个关键的 30是慢性肾脏疾病的贡献者。

1  Project Summary/Abstract 2  Mentored Phase: Sickle cell disease (SCD), the most common hemoglobinopathy in US, is associated with 3  high prevalence of end-stage kidney failure at the median 23 years of age. Due to the lack of kidney-targeted 4  treatment the mean survival is less than 3 years. SCD milieu induces endothelin-1 (ET-1) and elevated ET-1 5  levels in SCD patients correlate with microalbuminuria. I recently demonstrated that both ET receptor A (ETA) 6  and dual ET receptor A and B (ETA+B) antagonists prevented the increase in glomerular permeability to albumin 7  in a mouse model of SCD, but only the ETA receptor antagonist prevented albuminuria. These findings led me 8  to the hypothesis that ET-1 via ETA receptor activation contributes to renal injury in SCD mice, while the ETB 9  receptor provides tubular protection. Thus, the central hypothesis of the mentored phase is that in the SCD 10  milieu, elevated ET-1 and increased ETA receptor activity mediate tubular dysfunction leading to the 11  tubular injury in SCD mice, which is opposed by the ETB activity. The specific aim 1 of the mentored 12  phase will determine if increased ET-1 and the ETA receptor activity mediate tubular injury by decreased 13  tubular albumin uptake mechanism in SCD mice and if ETB receptor antagonism exacerbates ET-1 effects on 14  tubular albumin handling. With the use of new training in in vivo imaging techniques, I will track fluorescent- 15  labeled albumin to assess tubular albumin reabsorption in vehicle- or ET receptor antagonists treated SCD and 16  genetic control mice. We will also determine the direct effect of ET-1 and ET receptors on proximal tubule 17  albumin transporters in ex vivo and in vivo settings. Independent Phase: This phase will focus on an 18  independent line of investigation exploring mechanisms of renal iron handling that builds on previous training. 19  Evidence suggests that increased iron deposition in SCD is associated with albuminuria, both of which can be 20  attenuated by ETA receptor blockade. Although, ET-1 contributes to glomerulopathy in SCD, the relevance of 21  iron-induced toxicity and resultant tubular injury is unclear. Therefore, the overall hypothesis of the 22  independent phase is that elevated ET-1 leads to dysfunctional tubular iron handling, iron overload, and 23  tubular injury in SCD. This will be tested through in vitro experiments on cultured proximal tubules cells and 24  in vivo in SCD mice. The specific aim 2 will determine if impaired tubular iron handling in SCD leads to iron 25  overload via ET-1 induced increase in proximal tubule iron uptake and/or decrease in proximal tubule iron 26  removal. The specific aim 3 will determine mechanisms of iron toxicity that lead to tubular injury in SCD. This 27  will be tested by determining if renal iron-overload leads to tubular injury via oxidative stress and/or 28  mitochondrial dysfunction in SCD nephropathy. The goals of the proposed studies will undoubtedly shed light 29  on novel mechanistic pathways involved in the development and progression of tubular injury, a crucial 30  contributor in chronic kidney disease.