Control of fibroblast function by prostaglandin E2 and plasminogen activation

描述（由申请人提供）：成纤维细胞是通过其增强存活、增殖、胶原沉积和肌成纤维细胞分化的能力介导特发性肺纤维化（IPF）中组织重塑的主要效应细胞。尽管肺纤维化发病机制的研究主要是研究成纤维细胞活化信号，但有证据表明，这种疾病的特征还在于反调节抗纤维化信号的相对缺乏。两种这样的抗纤维化信号是前列腺素类前列腺素E2（PGE 2）和纤溶酶原激活物（PA）活性。在IPF患者中，上述每一种蛋白质均被证明缺乏，并且在肺纤维化动物模型中，每一种蛋白质的缺乏均被证实具有重要的病理学意义。PGE 2是一种脂质介质，来源于脂肪酸花生四烯酸的环氧合酶代谢，通过细胞表面G蛋白偶联的E前列腺素受体发挥作用。PA系统是一种蛋白水解级联反应，包括蛋白酶尿激酶型PA（uPA）及其相关抑制剂（纤溶酶原激活物抑制剂-1）。尽管PGE 2通过细胞内环AMP（cAMP）信号传导抑制肺成纤维细胞中所有相关促纤维化细胞表型的活化，但其这样做的下游机制尚不完全清楚。PA系统被认为是协调纤维蛋白溶解和调节细胞粘附和细胞信号传导，但很少有人知道它对成纤维细胞或其相关表型的直接影响。最后，没有关于任何种类的肺细胞（包括成纤维细胞）中PGE 2和PA系统之间的串扰的信息。该项目旨在了解两种介质调节成纤维细胞功能的机制，以表征它们之间的串扰，并确定纤维化肺损伤如何影响成纤维细胞对它们中每一种的反应。一般的假设是PGE 2和PA系统相互上调并相互作用，以有利于肺修复而不是纤维化的方式影响肺成纤维细胞表型。将在成纤维细胞系和从正常和纤维化鼠和人肺分离的原代细胞中检验该假设。目的1研究cAMP激活的cAMP效应物蛋白激酶A和鸟苷酸交换蛋白以及磷酸酶PTEN在介导PGE 2对成纤维细胞表型的影响中的作用。目标2将确定PGE 2和PA活性相互影响表达的机制，而目标3将探讨每一个在介导另一个作用中的作用。目的4将比较PGE 2和PA活性对来源于正常与损伤的小鼠肺以及来源于组织学正常与IPF人肺的成纤维细胞表型的影响。拟议的研究将为这两种介质调节成纤维细胞活化提供新的见解，并将为未来治疗靶向这些分子的努力提供信息。公共卫生相关性：一种称为肺瘢痕形成（肺纤维化）的严重疾病的发展受到身体产生的两种物质前列腺素E2和尿激酶纤溶酶原激活剂的抑制。该提案将研究这两种物质如何作用和相互作用，以抑制被称为成纤维细胞的关键肺细胞类型的疤痕反应。这些研究将增强我们对疤痕反应如何调节的理解，并可能提供关于这些物质是否可以给予患者以治疗这种破坏性疾病的见解。

DESCRIPTION (provided by applicant): Fibroblasts are the principal effector cells that mediate tissue remodeling in idiopathic pulmonary fibrosis (IPF) via their capacities for enhanced survival, proliferation, collagen deposition, and myofibroblast differentiation. Although research in the pathogenesis of pulmonary fibrosis has been dominated by studies investigating fibroblast activation signals, evidence indicates that this disorder is also characterized by a relative deficiency in counter-regulatory anti-fibrotic signals. Two such anti-fibrotic signals are the prostanoid prostaglandin E2 (PGE2) and plasminogen activator (PA) activity. Each of these has been shown to be deficient in patients with IPF, and deficiency of each has been established to be pathogenically important in animal models of pulmonary fibrosis. PGE2 is a lipid mediator derived from cyclooxygenase metabolism of the fatty acid arachidonic acid that acts via cell surface G protein-coupled E prostanoid receptors. The PA system is a proteolytic cascade that includes the protease urokinase-type PA (uPA) and its associated inhibitor (plasminogen activator inhibitor-1). Although PGE2 inhibits the activation of all relevant pro-fibrotic cellular phenotypes in lung fibroblasts via intracellular cyclic AMP (cAMP) signaling, the downstream mechanisms by which it does so are incompletely understood. The PA system is recognized to orchestrate fibrinolysis and to modulate cellular adhesion and cellular signaling, but little is known about its direct effects on fibroblasts or their relevant phenotypes. Finally, there is no information about cross-talk between PGE2 and the PA system in lung cells of any kind, including fibroblasts. This project seeks to understand the mechanisms by which both mediators modulate fibroblast function, to characterize the cross-talk between them, and to determine how fibrotic lung injury influences the responses of fibroblasts to each of them. The general hypothesis is that the PGE2 and PA systems up-regulate each other and interact to influence pulmonary fibroblast phenotypes in a manner which favors lung repair over fibrosis. This hypothesis will be tested in fibroblast cell lines and in primary cells isolated from normal and fibrotic murine and human lungs. Aim 1 will examine the roles of cAMP effectors protein kinase A and guanylate exchange protein activated by cAMP as well as the phosphatase PTEN in mediating PGE2 effects on fibroblast phenotypes. Aim 2 will determine the mechanisms by which PGE2 and PA activity influence the expression of each other, while the role of each in mediating the actions of the other will be explored in Aim 3. Aim 4 will compare the effects of PGE2 and PA activity on phenotypes of fibroblasts derived from normal vs. injured mouse lungs and from histologically normal vs. IPF human lungs. The proposed studies will provide novel insights into the regulation of fibroblast activation by these two mediators, and will inform future efforts to target these molecules therapeutically. PUBLIC HEALTH RELEVANCE: The development of a serious condition known as lung scarring (pulmonary fibrosis) is opposed by two substances produced by the body, prostaglandin E2 and urokinase plasminogen activator. This proposal will examine how these two substances act and interact to suppress scarring responses of the key lung cell type known as the fibroblast. These studies will enhance our understanding of how scarring responses are regulated, and may provide insight as to whether these substances could be administered to patients to treat this devastating condition.