Vascular ANGII/Jak2 in progression of renal disease

描述(申请人提供)：众所周知，不适当的血管紧张素II(AngII)激活在慢性肾脏疾病(CKD)的进展中起主要致病作用，无论启动原因如何。血管紧张素转换酶(Angii)的来源(血管、肾上皮细胞等)以及参与这一过程的信号通路尚不清楚。这项应用的目的是确定血管紧张素II(AngII)信号和Janus Kinase 2(JAK2)之间的偶联在CKD进展中的重要性。这一试点项目涉及一种新的条件性基因敲除小鼠的表型鉴定，该小鼠在VSMC中缺乏JAK2表达，并对慢性Angii诱导的高血压的发展具有抵抗力，暗示血管平滑肌JAK2信号通路的主要作用。我们的初步研究表明，VSMC JAK2基因缺失的小鼠对慢性血管紧张素Ⅱ诱导的CKD也具有高度的抵抗力，并且这种有益效果不依赖于压力。因此，我们假设是JAK2介导的血管紧张素转换酶II的肾脏活动是与大剂量慢性血管紧张素转换酶输注相关的高血压和慢性肾脏病的主要原因。第一个具体目标是扩展我们对慢性血管内皮细胞注射CKD模型的观察，并特别研究血管平滑肌细胞来源的JAK2在血管紧张素Ⅱ诱导的慢性肾功能不全过程中对肾功能和功能障碍的作用。第二个特定目的是使用肾交叉移植模型和肾内输注选择性JAK2抑制剂，以确定肾脏中VSMC来源的JAK2是否与Angii介导的高血压和CKD有关。在第三个特定目标中，我们将确定VSMC来源的JAK2的有害行为是否涉及抑制一氧化氮(NO)和增加活性氧自由基(ROS)。所有实验都将在FVB背景下进行。这些小鼠易患血管紧张素转换酶诱导性高血压和慢性肾脏病。VSMC JAK2缺失型为SM22？Cre(+)；Jak2fl/fl，对照为SM22？Cre(-)；Jak2fl/fl。所有被研究的动物都将被长期用于遥测血压测量，将进行代谢笼式研究以跟踪蛋白尿和总NO产生的发展，并将采集组织/血液以评估肾脏病理、24小时肌酐清除(Ccr)、NO和ROS产生的决定因素、血浆和肾组织Angii以及肾内肾素血管紧张素系统的转录、蛋白质和活动水平。总之，我们拟议的研究将(I)为我们的假设提供证据(Ii)提供更好的机制理解VSMC来源的JAK2如何介导慢性Angii反应CKD，以及(Iii)使我们能够将我们的研究转化为JAK2抑制剂治疗高血压和CKD的临床研究。 公共卫生相关性：血管紧张素II在许多形式的肾脏疾病的进展中起关键作用，该应用使用独特的转基因小鼠和新药来研究血管(血管平滑肌)中的血管紧张素II信号如何参与这一损伤过程。

DESCRIPTION (provided by applicant): It is well known that inappropriate angiotensin II (ANGII) activation plays a primary pathogenic role in the progression of chronic kidney disease (CKD), irrespective of the initiating cause. The source of the ANGII (vascular, renal epithelial, etc) and the signaling pathways that are involved in this process are poorly understood. The goal of this application is to establish the importance of the coupling between angiotensin II (ANGII) signaling and Janus kinase 2 (Jak2) in vascular smooth muscle cells (VSMC) in the progression of CKD. This pilot project involves the phenotyping of a novel conditional knockout mouse that lacks Jak2 expression within VSMC and is resistant to the development of chronic ANGII-induced hypertension, implicating a primary role of the vascular smooth muscle Jak2 signaling pathway. Our preliminary studies have demonstrated that the VSMC Jak2 null mouse is also highly resistant to chronic ANGII-induced CKD and this beneficial effect is pressure independent. Thus, we hypothesize that it is the renal actions of ANGII, mediated by Jak2, that are largely responsible for the hypertension and CKD associated with high dose chronic ANGII infusion. The first specific aim extends our observations on the chronic ANGII-infusion model of CKD and specifically investigates the role of VSMC-derived Jak2 on renal function and dysfunction during ANGII- induced CKD. The second specific aim uses a kidney cross transplant model and an intrarenal infusion of a selective Jak2 inhibitor to determine whether VSMC-derived Jak2 in the kidney is responsible for ANGII- mediated hypertension and CKD. In the third specific aim, we will determine if the deleterious actions of VSMC-derived Jak2, in response to chronic ANGII infusion, involve inhibition of nitric oxide (NO) and increases in reactive oxygen species (ROS). All experiments will be done on an FVB background. These mice are susceptible to ANGII-induced hypertension and CKD. The VSMC Jak2 null genotype is SM22¿Cre(+);Jak2fl/fl while the control genotype is SM22¿Cre(-);Jak2fl/fl. All animals studied will be chronically instrumented for blood pressure measurement by telemetry, will have metabolic cage studies to follow the development of proteinuria and total NO production and tissues/blood will be harvested for assessment of renal pathology, 24 hour creatinine clearance (Ccr), determinants of NO and ROS production, plasma and renal tissue ANGII and levels of components of the intrarenal renin angiotensin system at the transcript, protein and activity level. Collectively, our proposed studies will (i) provide evidence for our hypothesis (ii) provid a better mechanistic understanding for how VSMC-derived Jak2 mediates CKD in response to chronic ANGII and (iii) position us to translate our investigation into a clinical study for the us of Jak2 inhibitors for the treatment of hypertension and CKD. PUBLIC HEALTH RELEVANCE: Angiotensin II plays a key role in the progression of many forms of kidney disease and this application uses a unique transgenic mouse and novel drug to investigate how angiotensin II signaling in the blood vessel (vascular smooth muscle) contributes to this injury process.