Function of epithelial-mesenchymal transition during pulmonary fibrosis

描述（由申请人提供）：本申请的目的是确定不同细胞类型，特别是肺上皮细胞在肺纤维化发展中的作用。进行性纤维化是许多慢性疾病的共同特征，导致显著的发病率和死亡率。在诸如特发性肺纤维化（IPF）等疾病中，纤维化也可以在没有任何已知原因的情况下发生。指规炎是一种毁灭性疾病，影响全世界500多万人。中位生存期为3-5年，目前的药物治疗在很大程度上是无效的。尽管进行了深入的研究，但我们对调节纤维化的机制仍然知之甚少，甚至一些基本问题，如哪些细胞产生富含胶原的疤痕，仍然没有答案。先前的工作主要集中在成纤维细胞的功能上。然而，一种新的模式正在出现，其中上皮细胞的功能在决定纤维形成的进展中起着关键作用。这种可能性是令人兴奋的，因为上皮细胞的作用尚不明确，对上皮细胞行为调节机制的更清晰理解有可能为更好的治疗干预提供新的靶点。在过去的几年中，我们已经开发了几种技术来确定肺上皮细胞在纤维化过程中的功能和调控。通过动物模型，我们和其他人发现，在纤维形成过程中，上皮细胞能够在上皮-间质转化（EMT）过程中转化为成纤维细胞样细胞。在EMT过程中，肺上皮细胞可能获得产生I型胶原蛋白的能力，这是纤维化疤痕的主要成分。肺上皮细胞或任何其他细胞类型对富含胶原的纤维化的贡献程度仍然未知，我们已经产生了一种小鼠，我们可以在不同细胞类型中删除I型胶原基因。因此，我们将能够明确地确定哪种细胞类型在纤维形成过程中直接参与胶原合成。肺上皮细胞EMT对于募集其他胶原生成细胞也很重要。我们已经开发了一个系统来研究培养的肺上皮细胞，并确定它们是否释放信号分子，这些信号分子可以吸引和激活其他可能参与纤维形成的细胞类型。通过这种方式，肺上皮细胞可能在协调纤维化过程中起关键作用。最后，我们将研究一个转录因子家族，Helix- Loop-Helix （HLH）家族，它与EMT的调节有关。通过结合动物模型和细胞培养方法，我们将能够确定这些HLH因子是否调节上皮细胞产生胶原蛋白的能力，向其他细胞类型发出信号并调节纤维化。这些研究将有助于确定以前未探索的调节纤维化的机制，并有可能设计出新的更好的治疗方法。

DESCRIPTION (provided by applicant): The goal of this application is to define the role of different cell types, particularly lung epithelial cells, in the development pulmonary fibrosis. Progressive fibrosis is a common feature of many chronic diseases leading to significant morbidity and death. Fibrosis can also occur without any known cause in diseases such as Idiopathic Pulmonary Fibrosis (IPF). IPF is a devastating disease that affects greater than 5 million people world-wide. The median survival is 3-5 years from time of diagnosis and current medical therapy is largely ineffective. Despite intense investigation, we still have a poor understanding into the mechanisms that regulate fibrosis and even fundamental questions such as which cells produce the collagen-rich scar remain unanswered. Prior work has focused mainly on the function of fibroblasts. However, a new paradigm is emerging in which the function of epithelial cells plays a critical role in determining the progression of fibrogenesis. This possibility is exciting because the role of epithelial cells is undefined and a clearer understanding of the mechanisms that regulate epithelial cell behavior has the potential of offering new targets for better therapeutic intervention. We have developed several techniques in the last few years to define the function and regulation of lung epithelial cells during fibrogenesis. Using animal models, we and others have found that during fibrogenesis, epithelial cells are capable of transitioning into fibroblast-like cells in a process of epithelial-mesenchyma transition (EMT). During EMT, lung epithelial cells may acquire the ability to produce type I collagen which is the major component of the fibrotic scar. The extent to which lung epithelial cells or any other cell type contributes to the collagen-rich fibrosis remains unknown and we have generated a mouse in which we can delete the type I collagen gene in different cell types. Thus, we will be able to definitively determine which cell type(s) contribute directly to collagen synthesis during fibrogenesis. Lung epithelial cell EMT may also be important for recruiting other collagen-producing cells. We have developed a system to study lung epithelial cells in culture and determine if they release signaling molecules that can attract and activate other cells types potentially involved in fibrogenesis. In this way, lung epithelial cells may be critica in orchestrating the fibrotic process. Finally, we will study a family of transcription factors, the Helix- Loop-Helix (HLH) family that has been implicated in regulating EMT. Using combined animal model and cell culture approach we will be able to determine if these HLH factors regulate the ability of epithelial cells to produce collagen, signal to other cell types and regulae fibrosis. These studies will help define previously unexplored mechanisms that may regulate fibrosis with the potential of designing new and better therapies.