Novel Short ACE2 variant for Delayed Graft Function

项目摘要 移植肾功能延迟恢复（DGF）是急性肾损伤的一种形式，临床上定义为一个月内需要透析。 肾移植周它影响了多达50%的死亡供体肾移植受者。因为 器官短缺危机，边缘或扩大标准供体肾脏越来越多地被考虑， 这些肾脏发生DGF的风险更高。DGF患者发生同种异体移植排斥反应的风险较高， 死亡DGF主要由缺血引起的急性近端肾小管损伤引起。 迄今为止，还没有FDA批准的治疗方法。治疗或预防移植物功能延迟， 因此提出了未满足的临床需求，并且迫切需要预防和减轻DGF的新方法。 在这个建议中，我们想检查给予较短的血管紧张素转换酶抑制剂的预防价值。 酶2（ACE 2）变体。我们有初步的数据表明，一种短的小鼠ACE 2变体可以保护急性 缺血再灌注损伤（IRI）引起的肾损伤（阿基）。由于缺血再灌注损伤是 我们提出一种新的短的人类ACE 2变异体可以预防和减弱DGF。ACE 2是一个 肾脏中大量存在的一种组织酶，能裂解氨基酸苯丙氨酸形成血管紧张素（Ang）（1- 7)从Ang II（Ang（1-8））。在ACE 2缺乏的遗传模型中，缺血-再灌注诱导的阿基是 在阿基中已经报道了肾ACE 2活性的恶化和降低， 从Ang II形成Ang 1-7。因此，对阿基肾脏给予ACE 2是合理的 并通过扩展来预防/减弱DGF。 我们建议检查一种新的人类ACE 2变体的潜在预防/治疗作用， 比天然可溶性ACE 2短，因此可穿过肾小球滤过屏障， 可被肾脏近端小管吸收，促进血管紧张素Ⅱ的降解和血管紧张素Ⅱ的形成。 Ang 1-7.通过这种方法，血管紧张素II的形成继续，使得体循环和肾循环可以 通过这种关键肽维持，而不会引起低血压或损害肾小球血流动力学。 我们将我们较短的人ACE 2变体与白蛋白结合结构域（ABD）融合，作为延伸 作用持续时间从数小时到数天。我们计划在同系肾移植的小鼠中检测， 将这种新的ACE 2变体施用给接受了经受4小时寒冷的移植物的受体 缺血将改善延迟的移植物功能并增加肾脏ACE 2活性。此外，还将审查 如果在肾移植前用这种ACE 2变体离体灌注肾移植物可以防止 移植物功能延迟。

Project summary Delayed graft function (DGF) is a form of acute kidney injury clinically defined as the need for dialysis within one week of kidney transplantation. It affects up to 50% of deceased-donor kidney transplant recipients. Because of the organ shortage crisis, marginal or expanded criteria donor kidneys are increasingly considered even though these kidneys are at higher risk to develop DGF. Patients with DGF have a higher risk of allograft rejection and death. DGF is largely caused by acute proximal tubular injury induced by ischemia. There are no FDA-approved treatments available to date. Treatment or prevention of delayed graft function, therefore, poses an unmet clinical need and new approaches to prevent and attenuate DGF are urgently needed. In this proposal, we want to examine the preventative value of administering a shorter angiotensin converting enzyme 2 (ACE2) variant . We have preliminary data that a short mouse ACE2 variant protects against acute kidney injury (AKI) caused by ischemia reperfusion injury (IRI). As ischemia reperfusion injury is the driving force of DGF, we propose that a novel short human ACE2 variant can prevent and attenuate DGF. ACE2 is a tissue enzyme abundant in the kidneys that cleaves the amino acid phenylalanine to form Angiotensin (Ang) (1- 7) from Ang II (Ang (1-8)). In a genetic model of ACE2 deficiency, AKI induced by ischemia-reperfusion is aggravated and moreover a decrease in kidney ACE2 activity has been reported in AKI which leads to less formation of Ang 1-7 from Ang II. Therefore, there is a rationale for administering ACE2 to the kidney with AKI and by extension to prevent / attenuate DGF. We propose to examine the potential preventative / therapeutic effect of a novel human ACE2 variant which is shorter than the native soluble ACE2 and therefore filterable across the glomerular filtration barrier such that it can be taken up by the kidney proximal tubule where it fosters the degradation of Ang II and the formation of Ang 1-7. With this approach, the formation of Ang II continues, such that the systemic and renal circulation can be sustained by this critical peptide without causing hypotension or compromising glomerular hemodynamics. We have fused our shorter human ACE2 variant with an Albumin binding domain (ABD), as a strategy to extend the duration of action from hours to days. We plan to examine if in mice with syngeneic kidney transplantation administration of this novel ACE2 variant to the recipient that has received a graft subjected to 4 hours of cold ischemia will improve delayed graft function and increase kidney ACE2 activity. Additionally, it will be examined if perfusion of the kidney graft ex vivo with this ACE2 variant prior to kidney transplantation protects against delayed graft function.