Intercellular Signaling in Obstructive Nephropathy

虽然尿路梗阻是老年肾功能不全的主要原因，但尿路梗阻对肾脏的长期影响在发育中的肾脏中比在成熟肾脏中更为严重。单侧输尿管梗阻（UUO）后，肾内肾素-血管紧张素系统明显激活，单个肾单位的滤过不均匀。慢性单侧输尿管梗阻（UUO）的长期肾脏后果依赖于两种肾细胞群之间的平衡：那些经历进行性萎缩的肾细胞和那些保持结构完整性和功能的肾细胞。肾小管上皮（RTE）细胞凋亡或坏死，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细胞对UUO反应的细胞间信号传导机制。以下假设将被检验：1。局部血管对UUO的反应是通过肾小管上皮细胞（RTE）细胞向血管平滑肌和内皮细胞传递信号来调节的；2. 间质巨噬细胞通过RTE细胞和毛细血管内皮细胞的信号被吸引到扩张的小管中，从而调节RTE细胞对UUO的凋亡；3. 间质纤维化是由细胞因子信号传导到成纤维细胞和巨噬细胞。这些假设将通过检查新生儿和成年大鼠和小鼠的肾细胞对UUO的反应，以及RTE细胞、巨噬细胞和成纤维细胞的细胞培养来验证。通过肾素启动子表达GFP的突变小鼠和对大鼠的显微解剖将用于追踪UUO引起的肾微血管肾素表达的改变。血管内皮生长因子（VEGF）及其受体在UUO大鼠中的作用将被研究。我们将在β 2整合素缺乏的小鼠中研究整合素在UUO肾反应中的作用。在RTE细胞轴向拉伸模拟小管扩张的体外模型中，将研究负责RTE细胞与巨噬细胞之间以及RTE细胞与间质成纤维细胞之间交流的细胞因子。将从患有UUO的大鼠肾脏中收集肾间质液，以鉴定UUO增加的化合物及其间质浓度。这些化合物（生理浓度）的作用将在体外细胞系统中进行测试。在拟议的研究中，将在遭受UUO的大鼠的组织液中识别和定量信号分子。然后将使用肾小管细胞、巨噬细胞和成纤维细胞共培养来测试单个分子的作用。更好地了解不同肾细胞类型之间的串扰可能会带来新的方法来保护肾单位免受肾小管阻塞导致的细胞死亡。这将改善成年后的结果。

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.