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)是一种罕见的疾病，发生在接触基于GdBCA的造影剂(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激活的巨噬细胞、成纤维细胞和成纤维细胞。一些已发表的研究报道了注射大剂量GdBCA的大鼠肾次全切除后皮肤损害的发生，然而，这些损害并不表现出许多人类NSF损害的组织病理学特征。为了克服这一缺陷，我们建议开发一种更现实和更有信息的NSF动物模型，方法是使用腺嘌呤诱导的肾功能衰竭小鼠，这些小鼠要么静脉注射大剂量GdBCA，要么通过皮下植入渗透泵或气管内滴注GdBCA。鉴于人们对……角色的浓厚兴趣 为了探讨巨噬细胞，尤其是Toll样受体(TLR)通路在纤维化形成中的作用，我们将在这个新的模型中进行广泛的机制研究，以考察巨噬细胞和TLR在GdBCA诱导的纤维化发展中的作用。需要检验的假设是：1)GdBCA暴露诱导NSF样纤维化损害，2)激活的巨噬细胞诱导这些损害；3)诱导需要TLR4和/或TLR7的参与。为了验证这些假说，提出了以下具体目标：特异性目标1：以腺嘌呤所致肾功能衰竭的C57BL/6J小鼠为模型，给予GdBCA诱导纤维化。特异性目的2：探讨巨噬细胞及TLR4、TLR7在腺嘌呤肾病小鼠肾脏纤维化形成中的作用。这里提出的研究将提供关于将外源性或环境病因因素与炎症和纤维化相结合的初始分子事件的有价值的信息，重点是 先天免疫系统和TLR在这些过程中的反应。此外，这些研究将为特发性系统性纤维化疾病(如SSc)的发病机制提供重要线索，并可能确定这些疾病的新的潜在治疗靶点。

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.