Cellular Mechanisms of Renal Interstitial Fibrosis

描述(申请人提供)：肾脏疾病的进展会导致常见的后果，包括间质纤维化、肾小球硬化、血管狭窄和肾功能衰竭，最终需要透析或肾移植。肾脏肌成纤维细胞是肾脏纤维化过程中基质堆积的最主要细胞类型。虽然有大量的数据表明间质肌成纤维细胞基质合成的机制在肾纤维化的晚期，但关于肌成纤维细胞在基质堆积之前侵入血管周围和间质间隙的最早细胞事件的信息很少。在一种加速的肾纤维化模型中，肌成纤维细胞首先起源于血管周围和肾小球周围区域，实验被用来研究肌成纤维细胞侵占(迁移和增殖)的机制。我们的中心假设是：在肾纤维化早期，PDGFR-2和转化生长因子-β受体的激活通过Rho/ROCK调节ROS的产生和PI3-Kinase/Akt，MAPK(ERK1/2)信号转导通路，诱导成纤维细胞向肾小管周围间质迁移和增殖。目的1.NAD(P)H氧化酶来源的ROS参与肾间质纤维化早期的肌成纤维细胞侵袭；目的2.ROS诱导的间质肌成纤维细胞迁移、增殖和基质合成是PDGFR-2和转化生长因子-β受体激活的结果；目的3.通过PDGFR-2和转化生长因子-2受体产生ROS调节Smad2/3、Rho/ROCK、ERK1/2和Akt信号通路，启动间质肌成纤维细胞迁移、增殖和基质合成。PDGF BB和TGF2-1在血管疾病中启动ROS的产生。实验旨在关键地检测NAP(P)H氧化酶及其相关的Phox亚单位在体内和体外ROS生成、PDGFR-2和TGF-2受体激活以及在肌成纤维细胞迁移、增殖和基质合成中的信号通路中的作用。具体地说，NAD(P)H氧化酶途径(NOX2、NOX4和PHOX亚基)在Smads、Rho/ROCK、PI3K和ERK1/2调节肾脏肌成纤维细胞激活的PDGFR-2和TGF-2受体转导中的作用将被研究。这些研究将对肾纤维化早期肌成纤维细胞激活的机制提供亟需的见解。 公共卫生相关性：到目前为止，大多数关于肾间质纤维化的研究都集中在与基质堆积相关的晚期变化上，很少关注肌成纤维细胞侵入间质的早期事件(迁移和增殖)。在纤维化发生前了解肌成纤维细胞侵袭的机制可能会为慢性肾脏疾病的早期治疗提供新的治疗方法。这项应用侧重于在纤维化的早期阶段，活性氧物种(ROS)在肾肌成纤维细胞侵袭中的作用。

DESCRIPTION (provided by applicant): Progression of renal disease leads to common consequences including interstitial fibrosis, glomerulosclerosis, vascular narrowing, and renal failure, ultimately requiring dialysis or renal transplantation. The kidney myofibroblast is the cell type most responsible for matrix accumulation during renal fibrosis. Although there is a large amount of data on mechanisms of interstitial myofibroblast matrix synthesis late in the course of renal fibrosis, information on the earliest cellular events involving myofibroblast encroachment into the perivascular and interstitial spaces prior to matrix accumulation is lacking. Experiments are proposed to examine mechanisms of myofibroblast encroachment (migration and proliferation) in a model of accelerated renal fibrosis in which myofibroblasts first originate from perivascular and periglomerular regions. Our central hypothesis is: Activation of PDGFR-2 and TGF-beta receptor induces fibroblast migration and proliferation into the peritubular interstitium via Rho/ROCK modulated ROS generation and transduction of PI3-kinase/Akt, MAPK (ERK1/2) signaling pathways early during the progression of renal fibrosis. The following aims are set: Aim 1. NAD(P)H oxidase-derived ROS are involved in myofibroblast interstitial encroachment early during the course of kidney fibrosis; Aim 2. ROS-induced interstitial myofibroblast migration, proliferation and matrix synthesis is a consequence of PDGFR-2 and TGF- beta receptor activation; Aim 3. ROS generation through PDGFR-2 and TGF-2 receptor regulate SMAD2/3, Rho/ROCK, ERK1/2 and Akt signaling cascades, initiating interstitial myofibroblast migration, proliferation, and matrix synthesis. PDGF BB and TGF2-1 initiate ROS generation in vascular disease. Experiments are designed to critically examine a role for NAP(P)H oxidase and associated phox subunits in ROS generation, PDGFR-2 and TGF-2 receptor activation and signaling pathways on myofibroblast migration, proliferation and matrix synthesis in vitro and in vivo. Specifically, a role for the NAD(P)H oxidase pathway (Nox2 and Nox4 and phox subunits) will be examined in PDGFR-2 and TGF-2 receptor transduction of SMADs, Rho/ROCK, PI3K, and ERK1/2 regulation of activation of kidney myofibroblast. These studies will provide much needed insight on mechanisms of myofibroblast activation during the early stages of renal fibrosis. PUBLIC HEALTH RELEVANCE: To date, the majority of research on renal interstitial fibrosis has focused on late changes associated with matrix accumulation, with little attention on early events of myofibroblast encroachment (migration and proliferation) into the interstitium. Understanding the mechanisms of myofibroblast encroachment before fibrosis occurs could lead to new therapies in the early treatment of chronic renal disease. This application focuses on a role for reactive oxygen species (ROS) in renal myofibroblast encroachment early during the initial stages of fibrosis.