Intercellular Signaling in Obstructive Nephropathy

虽然尿路梗阻是老年肾功能不全的主要原因，但尿路梗阻的长期肾脏后果在发育中的肾脏中比成熟的肾脏更严重。 单侧输尿管梗阻（UUO）后，肾内肾素-血管紧张素系统明显激活，单个肾单位间滤过不均一。 慢性单侧输尿管梗阻（UUO）的长期肾脏后果取决于两种肾单位群体之间的平衡：进行性萎缩的肾单位群体和保持结构完整性和功能的肾单位群体。 肾小管上皮（RTE）细胞发生凋亡或坏死，导致肾小管萎缩。 这与进行性间质纤维化和肾小球硬化有关。 本项目的目的是确定肾单位对UUO反应的细胞间信号机制。 以下假设将被测试：1。局部血管对UUO的反应是通过从肾小管上皮细胞（RTE）细胞到血管平滑肌和内皮细胞的信号传递来调节的; 2. RTE细胞响应UUO的细胞凋亡受到来自RTE细胞和毛细血管内皮细胞的信号吸引到扩张小管的间质巨噬细胞的调节; 3.间质纤维化是由细胞因子信号传导至成纤维细胞和巨噬细胞介导的。 将通过检查新生和成年大鼠和小鼠对UUO的肾细胞反应以及RTE细胞、巨噬细胞和成纤维细胞的细胞培养来检验这些假设。 将使用具有由肾素启动子表达的GFP的突变小鼠和大鼠的显微切割来追踪由UUO引起的改变的肾微血管肾素表达。将在UUO大鼠中研究血管内皮生长因子（VEGF）及其受体的作用。 将在β 2整联蛋白缺陷小鼠中检查整联蛋白在对UUO的肾反应中的作用。 将在通过RTE细胞的轴向拉伸模拟的肾小管扩张的体外模型中检查负责RTE细胞和巨噬细胞之间以及RTE细胞和间质成纤维细胞之间的通信的细胞因子。 将从UUO大鼠的肾脏中采集肾间质液，以鉴定UUO增加的化合物及其间质浓度。 然后将使用体外细胞系统测试这些化合物（生理浓度）的作用。 在拟定的研究中，将在UUO大鼠的间质液中鉴别和定量信号分子。 然后使用肾小管细胞、巨噬细胞和成纤维细胞的共培养物来测试单个分子的作用。 更好地理解不同肾细胞类型之间的串扰可能会导致新的方法来保护肾单位免受发育中的肾中肾小管阻塞引起的细胞死亡。 这将有助于改善成年后的结果。

While urinary tract obstruction is a major cause of renal insufficiency at ages, the long-term renal consequences of urinary tract obstruction are more severe in the developing kidney than in the mature kidney. Following unilateral ureteral obstruction (UUO), there is marked activation of the intrarenal renin-angiotensin system, and heterogeneity in filtration among individual nephrons. The long-term renal consequences of chronic unilateral ureteral obstruction (UUO) are dependent on the balance between two nephron populations: those undergoing progressive atrophy, and those that maintain structural integrity and function. Renal tubular epithelial (RTE) cells undergo apoptosis or necrosis, leading to tubular atrophy. This is associated with progressive interstitial fibrosis and glomerular sclerosis. The aim of this project is to identify the intercellular signaling mechanisms underlying the nephron response to UUO. The following hypotheses will be tested: 1. the regional vascular response to UUO is modulated by the transmission of signals from the renal tubular epithelial cells (RTE) cells to vascular smooth muscle and endothelial cells; 2. apoptosis of RTE cells in response to UUO is modulated by interstitial macrophages attracted to dilated tubules by signals from RTE cells and capillary endothelial cells; 3. Interstitial fibrosis is mediated by cytokine signaling to fibroblasts and macrophages. These hypotheses will be tested by examining the renal cellular responses to UUO in neonatal and adult rats and mice, as well as cell culture of RTE cells, macrophages, and fibroblasts. Mutant mice with GFP expressed by the renin promoter and microdissection of rats will be used to track altered renal microvascular renin expression resulting from UUO. The role of vascular endothelial growth factor (VEGF) and its receptors will be studied in rats with UUO. The role of integrins in the renal response to UUO will be examined in beta2 integrin deficient mice. The cytokines responsible for communication between RTE cells and macrophages and between RTE cells and interstitial fibroblasts will be examined in an in vitro model of tubular dilatation simulated by axial stretch of RTE cells. Renal interstitial fluid will be collected from kidneys from rats with UUO to identify the compounds increased by UUO, as well as their interstitial concentration. The effects of these compounds (in physiologic concentrations) will then be tested using in vitro cell systems. In the proposed studies, the signaling molecules will be identified and quantitated in interstitial fluid from rats subjected to UUO. The role of individual molecules will then be tested using cocultures of renal tubular cells, macrophages, and fibroblasts. It is likely that a better understanding of the crosstalk between different renal cell types will lead to new approaches to protect nephrons from cell death resulting from tubular obstruction in the developing kidney. This will lead to improved outcomes in adulthood.