Role of toll like receptors (TLRs)in Gd contrast agent induced skin fibrosis

描述（由申请人提供）：肾源性系统性纤维化（NSF）是一种罕见疾病，发生于暴露于钆基造影剂（GdBCA）后的一小部分肾功能不全患者中。这种疾病的特征是严重的皮肤和全身纤维化，在受影响的组织中存在大量活化的巨噬细胞、纤维细胞和成纤维细胞。几项已发表的研究报告了注射高剂量GdBCA的次全肾切除啮齿动物中皮肤病变的发展，然而，这些病变并未表现出人类NSF病变的许多组织病理学特征。为了克服这一缺陷，我们建议开发一个更现实的和翔实的动物模型NSF利用小鼠腺嘌呤诱导的肾功能衰竭，无论是静脉注射高剂量GdBCA或已暴露于GdBCA通过皮下植入渗透泵或intraperitheal滴注。考虑到人们对这一角色的浓厚兴趣， 为了研究巨噬细胞，特别是Toll样受体（TLR）途径在纤维化发展中的作用，我们将进行广泛的机制研究，以检查巨噬细胞和TLR在这种新模型中GdBCA诱导的纤维化发展中的作用。 待检验的假设将为：1）GdBCA暴露诱导NSF样纤维化病变，2）需要活化的巨噬细胞来诱导这些病变;和3）诱导需要TLR 4和/或TLR 7的参与。为了检验这些假设，提出了以下具体目的：具体目的1：在具有腺嘌呤诱导的肾衰竭的C57 BL/6 J小鼠中通过GdBCA施用诱导纤维化。具体目的2：研究巨噬细胞和TLR 4和TLR 7在腺嘌呤诱导的肾病小鼠纤维化发展中的作用。本文提出的研究将提供关于将外源性或环境致病因素与炎症和纤维化偶联的初始分子事件的有价值的信息，重点关注炎症和纤维化的参与。 先天免疫系统和TLR反应在这些过程中。此外，这些研究将提供有关特发性系统性纤维化疾病（如SSc）发病机制的重要线索，并可能为这些疾病确定新的潜在治疗靶点。

DESCRIPTION (provided by applicant): Nephrogenic Systemic Fibrosis (NSF) is a rare condition occurring in a small subset of patients with renal insufficiency following exposure to Gadolinium based contrast agents (GdBCA). This disorder is characterized by severe dermal and systemic fibrosis with the presence of large numbers of activated macrophages, fibrocytes and fibroblasts in affected tissues. Several published studies have reported the development of skin lesions in sub-total nephrectomized rodents injected with high doses of GdBCA, however, these lesions do not demonstrate many of the histopathological characteristics of human NSF lesions. To overcome this flaw, we propose to develop a more realistic and informative animal model of NSF by utilizing mice with adenine-induced renal failure that have either been injected intravenously with high dose GdBCA or that have been exposed to GdBCA via subdermally implanted osmotic pumps or by intratracheal instillation. Given the intense interest in the role of macrophages and, in particular, of the Toll-like receptor (TLR) pathway in the development of fibrosis, we will perform extensive mechanistic studies to examine the role of macrophages and TLRs in the development of GdBCA induced fibrosis in this new model. The hypotheses to be tested will be: 1) GdBCA exposure induces NSF-like fibrotic lesions, 2) activated macrophages are required to induce these lesions; and 3) the induction requires engagement of TLR4 and/or TLR7. To test these hypotheses, the following specific aims are proposed: SPECIFIC AIM 1: Induce fibrosis by GdBCA administration in C57BL/6J mice with adenine induced renal failure. SPECIFIC AIM 2: Investigate the role of macrophages and of TLR4 and TLR7 in the development of fibrosis in mice with adenine induced renal disease. The studies proposed here will provide valuable information regarding the initial molecular events that couple exogenous or environmental etiologic factors with inflammation and fibrosis focusing on the participation of the innate immunity system and TLR responses in these processes. Furthermore, these studies will provide important clues regarding the pathogenesis of idiopathic systemic fibrotic disorders such as SSc and may allow the identification of novel potential therapeutic targets for these diseases.