Division of Nephrology and Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
The Feinberg Cardiovascular and Renal Research Institute, Chicago, Illinois.
J Am Soc Nephrol. 2023 Jun 1;34(6):969-987. doi: 10.1681/ASN.0000000000000098. Epub 2023 Feb 14.
Ischemia-reperfusion AKI (IR-AKI) is common and causes significant morbidity. Effective treatments are lacking. However, preclinical studies suggest that inhibition of angiopoietin-Tie2 vascular signaling promotes injury, whereas activation of Tie2 is protective. We show that kidney ischemia leads to increased levels of the endothelial-specific phosphatase vascular endothelial protein tyrosine phosphatase (VE-PTP; PTPRB), which inactivates Tie2. Activation of Tie2 through VE-PTP deletion, or delivery of a novel angiopoietin mimetic (Hepta-ANG1), abrogated IR-AKI in mice. Single-cell RNAseq analysis showed Tie2 activation promotes increased Entpd1 expression, downregulation of FOXO1 target genes in the kidney vasculature, and emergence of a new subpopulation of glomerular endothelial cells. Our data provide a molecular basis and identify a candidate therapeutic to improve endothelial integrity and kidney function after IR-AKI.
Ischemia-reperfusion AKI (IR-AKI) is estimated to affect 2%-7% of all hospitalized patients. The significant morbidity and mortality associated with AKI indicates urgent need for effective treatments. Previous studies have shown activation of the vascular angiopoietin-Tie2 tyrosine kinase signaling pathway abrogates ischemia-reperfusion injury (IRI). We extended previous studies to (1) determine the molecular mechanism(s) underlying kidney injury and protection related to decreased or increased activation of Tie2, respectively, and (2) to test the hypothesis that deletion of the Tie2 inhibitory phosphatase vascular endothelial protein tyrosine phosphatase (VE-PTP) or injection of a new angiopoietin mimetic protects the kidney from IRI by common molecular mechanism(s).
Bilateral IR-AKI was performed in VE-PTP wild-type or knockout mice and in C57BL/6J mice treated with Hepta-ANG1 or vehicle. Histologic, immunostaining, and single-cell RNA sequencing analyses were performed.
The phosphatase VE-PTP, which negatively regulates the angiopoietin-Tie2 pathway, was upregulated in kidney endothelial cells after IRI, and genetic deletion of VE-PTP in mice protected the kidney from IR-AKI. Injection of Hepta-ANG1 potently activated Tie2 and protected the mouse kidney from IRI. Single-cell RNAseq analysis of kidneys from Hepta-ANG1-treated and vehicle-treated mice identified endothelial-specific gene signatures and emergence of a new glomerular endothelial subpopulation associated with improved kidney function. Overlap was found between endothelial-specific genes upregulated by Hepta-ANG1 treatment and those downregulated in HUVECs with constitutive FOXO1 activation, including Entpd1 / ENTPD1 that modulates purinergic receptor signaling.
Our data support a key role of the endothelium in the development of IR-AKI, introduce Hepta-ANG1 as a putative new therapeutic biologic, and report a model to explain how IRI reduces Tie2 signaling and how Tie2 activation protects the kidney.
This article contains a podcast at https://dts.podtrac.com/redirect.mp3/www.asn-online.org/media/podcast/JASN/2023_05_23_JSN_Ang_EP23_052323.mp3.
缺血再灌注急性肾损伤（IR-AKI）很常见，会导致严重的发病率。目前缺乏有效的治疗方法。然而，临床前研究表明，血管生成素-Tie2 血管信号的抑制会促进损伤，而 Tie2 的激活则具有保护作用。我们发现，肾脏缺血会导致内皮特异性磷酸酶血管内皮蛋白酪氨酸磷酸酶（VE-PTP；PTPRB）水平升高，从而使 Tie2 失活。通过 VE-PTP 缺失或递送新型血管生成素模拟物（Hepta-ANG1）激活 Tie2，可消除小鼠的 IR-AKI。单细胞 RNAseq 分析表明，Tie2 的激活可促进 Entpd1 的表达增加，下调肾脏血管中 FOXO1 靶基因的表达，并出现新的肾小球内皮细胞亚群。我们的数据提供了一个分子基础，并确定了一种候选治疗方法，可改善 IR-AKI 后的内皮完整性和肾功能。
据估计，缺血再灌注急性肾损伤（IR-AKI）影响所有住院患者的 2%-7%。AKI 相关的显著发病率和死亡率表明急需有效的治疗方法。先前的研究表明，血管生成素-Tie2 酪氨酸激酶信号通路的激活可消除缺血再灌注损伤（IRI）。我们扩展了之前的研究，以确定（1）分别与 Tie2 活性降低或升高相关的肾脏损伤和保护的分子机制，以及（2）假设 VE-PTP（一种 Tie2 抑制性磷酸酶）缺失或注射新型血管生成素模拟物是否通过共同的分子机制保护肾脏免受 IRI。
在 VE-PTP 野生型或敲除小鼠以及接受 Hepta-ANG1 或载体治疗的 C57BL/6J 小鼠中进行双侧 IR-AKI。进行组织学、免疫染色和单细胞 RNA 测序分析。
IRI 后，肾脏内皮细胞中负调控血管生成素-Tie2 通路的磷酸酶 VE-PTP 上调，而 VE-PTP 在小鼠中的基因缺失可保护肾脏免受 IR-AKI。Hepta-ANG1 的注射可强烈激活 Tie2，并保护小鼠的肾脏免受 IRI。对 Hepta-ANG1 治疗和载体治疗的小鼠肾脏进行单细胞 RNAseq 分析，确定了与改善肾功能相关的内皮特异性基因特征和新的肾小球内皮亚群的出现。Hepta-ANG1 处理上调的内皮特异性基因与 HUVECs 中组成型 FOXO1 激活下调的基因之间存在重叠，包括调节嘌呤能受体信号的 Entpd1/ENTPD1。
我们的数据支持内皮在 IR-AKI 发展中的关键作用，引入 Hepta-ANG1 作为一种潜在的新型治疗生物，并报告了一种解释 IRI 如何降低 Tie2 信号以及 Tie2 激活如何保护肾脏的模型。
