Hyaluronan in Pulmonary Fibrosis and Asthma

说明)： 控制组织重塑的分子机制仍不完全清楚。本节目 侧重于阐明细胞外基质在调节肺部炎症和纤维化中的作用。一个 在慢性肺部疾病的病理生物学中尚未回答的关键问题是什么是决定因素 疾病进展和不可逆转的功能丧失。持续性肺部炎症和纤维化是导致 主要发病率和死亡率，无论是发生在主要途径，如慢性哮喘，还是发生在间质，如 特发性间质性肺炎，如特发性肺纤维化(IPF)。我们已经产生了一具 已确定糖胺聚糖透明质酸(HA)及其同源受体具有 在非感染性肺损伤背景下调节肺部炎症和纤维化的重要作用。HA是 一种不寻常的大分子，因为它是在细胞膜上合成的，并被挤出到细胞外 并在发炎时变得支离破碎。在过去的17年里，我们实验室的工作 根据其细胞环境确定HA在非感染性肺损伤中的不同功能 表达以及它呈现给相互作用的细胞的形式。HA在肺的上下文中被修饰 炎症和分解产物会积累起来，从而促进炎症。我们还发现， 表达于肺上皮细胞表面的透明质酸对非感染性肺损伤具有保护作用 侮辱。相反，当肌肉成纤维细胞被定向过表达透明质酸合成酶2(HAS2)时， 结果是一种严重的、进行性的损伤后纤维破坏性肺部疾病，导致显著的死亡。 肺间质纤维化的病理特征之一是肺泡内皮细胞基底膜的破坏。 界面，我们开始研究成纤维细胞对基质的侵袭是否可能是 无休止的纤维化。我们已经做了令人兴奋的观察，从转基因小鼠中分离出成纤维细胞 在D-平滑肌肌动蛋白启动子的指导下过表达HAS2具有侵袭性 转基因阴性对照成纤维细胞的表型。我们还开发了第一个型号的 靶向缺失间充质细胞中的HAS2发现肺纤维化的发展 受伤是受损的。此外，我们发现透明质酸在肺裂中显著堆积，使用一种新的 小鼠慢性哮喘模型，可导致呼吸道纤维化。总体而言，该系统提供了独特的 在两个不同的模型系统中剖析控制持续性纤维化的机制的方法。 此外，我们还发现，从患有严重特发性疾病的患者中分离出的成纤维细胞 肺纤维化和慢性哮喘表现为侵袭性表型。 基于这些来自新的小鼠模型以及人类疾病的数据，我们产生了 假设持续性炎症和持续性纤维化都是由积聚引起的 与需要透明质酸的侵袭性成纤维细胞表型的发展 合酶2和透明质酸结合蛋白，如CD44。我们将在以下目标中检验这一假设： 具体目的1.确定透明质酸合成酶2(HAS2)过表达的机制 CD44调节严重的肺纤维化和侵袭性成纤维细胞表型的发展。 特定目的2.确定透明质酸合成酶2(HAS2)和CD44在调节血管内皮细胞生长中的作用 慢性哮喘小鼠模型的哮喘表型和进行性气道重塑 HAS2在肌成纤维细胞中的靶向性过表达及肺上皮和肺上皮细胞中HAS2的缺失 间充质细胞。 特定目的3.确定HAS2和CD44在调节侵袭性成纤维细胞表型中的作用 IPF患者。 相关性(请参阅说明)： 本项目(项目1)是该项目研究内源激素的作用的全球目标的组成部分 基质成分通过与同源受体相互作用推动持续的肺部炎症和炎症 导致侵袭性成纤维细胞表型的发展。项目1将与项目2紧密对接 (Wright博士)，因为这些概念将在表面活性剂缺乏的背景下进行研究。项目1还将 与项目3(克拉夫特博士)密切合作，以确定透明质酸及其受体在 小鼠和人哮喘的病理生物学。

instrucfions): The molecular mechanisms that control tissue remodeling remain incompletely understood. This program has focused on elucidafing the role of extracellular matrix in regulafing lung inflammafion and fibrosis. A crifical unanswered question in the pathobiology of chronic lung diseases is what are the determinants of disease progression and irreversible loss of funcfion. Persistent lung inflammation and fibrosis is a cause of major morbidity and mortality whether it occurs in the ainways as in chronic asthma or in the interstifium as in idiopathic interstitial pneumonias such an idiopathic pulmonary fibrosis (IPF). We have generated a body of work that has identified the glycosaminoglycan hyaluronan (HA) and its cognate receptors as having important roles in regulating lung inflammation and fibrosis in the context of noninfectious lung injury. HA is an unusual macromolecule in that it is synthesized at the cell membrane and extruded into the extracellular milieu and becomes fragmented during inflammafion. Work from our laboratory over the last 17 years has identified distinct functions for HA in noninfectious lung injury depending on both the cellular context of its expression and the form in which it is presented to interacting cells. HA is modified in the context of lung inflammation and breakdown products accumulate that promote inflammation. We have also discovered that HA expressed on the cell surface of lung epithelial cells serves a protective function against noninfectious insults. In contrast, when myofibroblasts are directed to over-express hyaluronan synthase 2 (HAS2),.the result is a severe and progressive fibrodestructive lung disease after injury that causes significant mortality. One of the pathologic hallmarks of IPF is the destruction of basement membrane at the alveolar-endothelial interface and we began to investigate whether fibroblast invasion of matrix could be an important feature of unremitting fibrosis. We have made the exciting observation that fibroblasts isolated from transgenic mice that over-express HAS2 under the direction of the D-smooth muscle actin promoter have an invasive phenotype relative to transgene negative control fibroblasts. We have also developed the first model of targeted deletion of HAS2 in mesenchymal cells and found that the development of fibrosis following lung injury is impaired. In addifion, we have found a marked accumulation of HA in lung fissue using a novel chronic model of asthma in mice that causes ainway fibrosis. Collectively, this system offers unique approaches to dissect the mechanisms that control persistent fibrosis in two distinct model systems. Furthermore, we have also found that fibroblasts isolated from patients that have severe idiopathic pulmonary fibrosis and chronic asthma demonstrate an invasive phenotype. Based on these data from novel mouse models as well as human diseases we have generated the hypothesis that persistent inflammation and unremitting fibrosis is driven by both the accumulation of HA fragments and the development of an invasive fibroblast phenotype that requires hyaluronan synthase 2 and HA binding proteins such as CD44. We will test this hypothesis in the following Aims: Specific Aim 1. Determine the mechanisms by which over-expression of hyaluronan synthase 2 (HAS2) and CD44 regulate severe lung fibrosis and the development of an invasive fibroblast phenotype. Specific Aim 2. Determine the roles of hyaluronan synthase 2 (HAS2) and CD44 in regulafing the asthma phenotype and progressive ainway remodeling in a chronic model of mouse asthma using mice with targeted over-expression of HAS2 in myofibroblasts and deletion of HAS2 in lung epithelial and mesenchymal cells. Specific Aim 3. Determine the role of HAS2 and CD44 in regulating the invasive fibroblast phenotype in patients with IPF. RELEVANCE (See instructions): This project (Project 1) is an integral part of the global goal of this program to study the role of endogenous matrix components in driving unremitting lung inflammation and fitirosis by interacting with cognate receptors leading to the development of an invasive fibroblast phenotype. Project 1 will interface closely with Project 2 (Dr. Wright), as these concepts will be investigated in the context of surfactant deficiency. Project 1 will also interface closely with Project 3 (Dr. Kraft) to determine the roles of hyaluronan and its receptors in the pathobiology of asthma in mouse and man.