Vascular ANGII/Jak2 in progression of renal disease

描述（由申请方提供）：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）进展中起主要致病作用，无论起始原因如何。ANGII的来源（血管、肾上皮等）和参与该过程的信号通路知之甚少。本申请的目的是确定血管平滑肌细胞（VSMC）中血管紧张素II（ANGII）信号传导和Janus激酶2（Jak 2）之间的偶联在CKD进展中的重要性。该试点项目涉及一种新型条件性基因敲除小鼠的表型，该小鼠在VSMC内缺乏Jak 2表达，并且对慢性ANGII诱导的高血压的发展具有抗性，这暗示了血管平滑肌Jak 2信号通路的主要作用。我们的初步研究表明，VSMC Jak 2敲除小鼠对慢性ANGII诱导的CKD也具有高度抗性，并且这种有益作用与压力无关。因此，我们假设是由Jak 2介导的ANGII的肾脏作用，其在很大程度上负责与高剂量慢性ANGII输注相关的高血压和CKD。 第一个具体目的扩展了我们对慢性ANGII输注CKD模型的观察，并具体研究了VSMC衍生的Jak 2对ANGII诱导的CKD期间肾功能和功能障碍的作用。第二个具体目标使用肾交叉移植模型和选择性Jak 2抑制剂的肾内输注来确定肾脏中VSMC衍生的Jak 2是否是ANGII介导的高血压和CKD的原因。在第三个具体目标中，我们将确定VSMC衍生的Jak 2响应于慢性ANGII输注的有害作用是否涉及抑制一氧化氮（NO）和增加活性氧（ROS）。所有实验都将在FVB背景下进行。这些小鼠易患ANGII诱导的高血压和CKD。VSMC Jak 2基因缺失型为SM 22 <$Cre（+）; Jak 2fl/fl，对照基因型为SM 22 <$Cre（-）;所有研究的动物将长期装备仪器以通过遥测进行血压测量，将进行代谢笼研究以跟踪蛋白尿和总NO产生的发展，并将收获组织/血液以评估肾脏病理学、24小时肌酐清除率（Ccr），NO和ROS产生的决定因素，血浆和肾组织ANGII和肾内肾素血管紧张素系统的组分在转录物、蛋白质和活性水平上的水平。 总的来说，我们提出的研究将（i）为我们的假设提供证据（ii）为VSMC衍生的Jak 2如何介导CKD以响应慢性ANGII提供更好的机制理解和（iii）使我们能够将我们的研究转化为Jak 2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着关键作用，本申请使用独特的转基因小鼠和新型药物来研究血管（血管平滑肌）中的血管紧张素II信号传导如何促成这种损伤过程。

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.