The role of Macrophage Delivered WNT Signaling in kidney injury and repair

描述(申请人提供)：慢性肾脏疾病是一种影响数百万人的公共卫生流行病。它对医疗保健、我们的社区和个人造成的损失是深远的。慢性肾脏疾病，以慢性炎症、实质细胞丢失和纤维化为特征。然而，当肾脏受伤时，它有巨大的恢复能力。了解正常恢复的机制以及它们与肾脏进行性炎症的不同将导致新的治疗方法。我们一直在研究巨噬细胞的作用，巨噬细胞是免疫系统招募到肾脏的细胞，在调节肾脏的正常修复过程和指导纤维化的发展方面发挥作用，纤维化是肾衰竭的先兆。我们发现，经典的WNT细胞间信号通路，调节细胞的生存、分化、迁移、增殖和凋亡，曾被认为仅限于胚胎发育和癌症的旁分泌细胞通讯，在肾脏修复和肾脏纤维化期间都是活跃的。我们的中心假设得到了大量初步数据的支持，即肾脏中的炎性巨噬细胞释放可溶性配体(WNT)，通过旁分泌细胞上的WNT受体传递信号，该信号在介导肾脏修复中发挥重要作用。然而，当损伤持续时，炎性巨噬细胞发出的WNT信号支持间质成纤维细胞的增加，并指导瘢痕组织的生成。在目标1中，我们将重点介绍损伤后正常的肾脏修复。我们将研究炎性巨噬细胞的确切作用，并剖析上皮细胞在向肾脏邻近细胞传递WNT信号方面的支持作用。我们将在小鼠中使用遗传学方法来研究：体内巨噬细胞有条件地消融对WNT信号的影响；WNT受体Frizzled4、LRP-5和LRP-6在肾脏修复中的重要性；以及体内巨噬细胞Wnt-7b或Wnt配体释放蛋白Wnless在修复中的作用。我们将使用WNT信号的可溶性调节剂来影响肾脏的修复。在AIM 2中，我们将把巨噬细胞传递的WNT信号集中在肾脏纤维化的进展上。利用小鼠的遗传学方法，我们将研究成纤维细胞WNT受体Frizzled7、巨噬细胞Wnt配体释放蛋白Wnless和成纤维细胞中转录调节因子-连环蛋白在体内纤维化进展中的作用。我们将测试包括Dickkopf-1和-2在内的可溶性WNT调节剂对纤维化进展的影响。相关性：这些研究的总体目的是确定来自巨噬细胞的典型WNT信号，特别是在正常肾脏修复中对上皮细胞的作用，以及对成纤维细胞在纤维化发展中的作用。通过了解巨噬细胞调节肾脏损伤和修复的机制，我们将开发新的治疗范例，支持正常修复，并对抗人类的纤维化。公共卫生相关性：慢性肾脏疾病是一种影响数百万人的公共卫生流行病，但肾脏具有巨大的康复能力。我们一直在研究免疫系统中一种名为巨噬细胞的细胞，它被招募到受损的肾脏，在肾衰竭的发展过程中发挥作用，但也在正常修复中发挥作用。我们发现，一种称为WNT信号的细胞-细胞通讯信号通路在受损的肾脏中活跃，并被肾脏中的巨噬细胞用来指导肾脏细胞的修复。WNT信号在癌症进展和正常胚胎发育中起关键作用。我们将研究这一复杂的细胞-细胞信号通路的分子组成，以发现可能导致肾脏疾病患者新疗法的新靶点。

DESCRIPTION (provided by applicant): Chronic kidney disease is a public health epidemic affecting millions. The toll to health care, our communities and to individuals is profound. Chronic kidney disease and is characterized by chronic inflammation, parenchymal cell loss and fibrosis. However the kidney when injured has enormous capacity for recovery. Understanding the mechanisms of normal recovery and how they differ from progressive inflammation in the kidney will lead to new therapies. We have been studying the role of macrophages, cells of the immune system recruited to the kidney, in regulating the normal repair process in the kidney and in directing the development of fibrosis, which is a harbinger of kidney failure. We have discovered that the Canonical WNT cell-to-cell signaling pathway, that regulates cell survival, differentiation, migration, proliferation and apoptosis, once thought to be restricted to paracrine cell communications of embryonic development and cancer, is active during kidney repair and also during kidney fibrosis. Our central hypothesis supported by extensive preliminary data is that inflammatory macrophages in the kidney release soluble ligands (WNTs) that signal via WNT receptors on paracrine cells and that this signaling plays an important role in mediating kidney repair. However when injury is persistent, WNT signaling from inflammatory macrophages supports the increase in interstitial fibroblasts and directs generation of scar tissue. In AIM 1 we will focus on normal kidney repair following injury. We will examine the precise role of inflammatory macrophages and dissect a supporting role from epithelial cells in delivering WNT signals to neighboring cells of the kidney. We will use genetic approaches in the mouse to study: the effect of conditional ablation of macrophages in vivo on WNT signaling; the importance of WNT receptors Frizzled-4, Lrp-5 and Lrp-6 in kidney repair; and the role of macrophage Wnt-7b or the Wnt ligand release protein Wntless in vivo, in repair. We will administer soluble modulators of WNT signaling to affect repair of the kidney. In AIM 2 we will focus Macrophage delivered WNT signaling on the progression of fibrosis in the kidney. Using genetic approaches in the mouse we will study the role of fibroblast WNT receptor Frizzled-7; the macrophage Wnt ligand release protein Wntless; and the transcriptional regulator ¿-catenin in fibroblasts, on fibrosis progression in vivo. We will test the impact of soluble WNT modulators including Dickkopf-1 and -2 on fibrosis progression. Relevance: The overall purpose of these studies is to determine the roles of Canonical WNT signaling from macrophages, particularly to epithelial cells in normal kidney repair, but also to fibroblasts in the development of fibrosis. By understanding the mechanisms by which macrophages regulate injury and repair in the kidney we will develop new therapeutic paradigms that support normal repair, and counteract fibrosis in humans. PUBLIC HEALTH RELEVANCE: Chronic kidney disease is a public health epidemic that affects millions yet the kidney has an enormous capacity for recovery. We have been studying a cell of the immune system called the macrophage that is recruited to the injured kidney and plays roles in both progression to kidney failure but also plays a role in normal repair. We have discovered that a cell-cell communication signaling pathway called WNT signaling, previously demonstrated to be pivotal in cancer progression and in normal embryonic development is active in the injured kidney and is used by macrophages in the kidney to direct repair of the cells of the kidney. We will study the molecular components of this complex cell-cell signaling pathway to discover new targets that may lead to new therapies for patients with kidney disease.