Targeting early events in MUC5B-driven lung injury and fibrosis

项目总结 项目3的总体目标是了解MUC5B在远端呼吸道中的错误表达增加是如何导致 蜂窝囊肿的形成、成纤维细胞的聚集、促纤维化的程序化和最终的纤维化反应 至远端呼吸道和肺泡上皮损伤。通过在小鼠模型和在体内进行的研究相结合 对人类肺上皮细胞和成纤维细胞的体外研究，项目3试图通过测试来填补这一知识空白 远端呼吸道上皮细胞MUC5B错误表达和持续内质网应激的假说 肺泡上皮细胞和远端呼吸道上皮细胞对凋亡的易感性导致 纤维化和蜂窝囊形成。我们将解决以下机械性问题：(I)如何 远端呼吸道上皮细胞MUC5B错误表达易导致细胞凋亡诱导 成纤维细胞堆积、促纤维化编程、纤维化和蜂窝囊形成，(Ii)相对作用(S) 肺泡和远端呼吸道上皮细胞凋亡在纤维化和蜂窝囊肿发展中的作用 (Iii)从补救的角度来看，如果预防上皮细胞凋亡可以缓解肺间质纤维化的发展 纤维化和蜂窝囊形成。虽然对肺泡上皮细胞的作用已经了解很多， 细胞凋亡在纤维化的发展中，这些研究大多是在发现之前增加的 MUC5B错误表达导致的IPF易感性。项目3试图解决这一知识鸿沟。目标1 将检验这一假设，即在远端气道MUC5B增加的情况下，肺泡上皮细胞凋亡 表达错误，会导致小鼠肝纤维化，但不会形成蜂窝囊。这一假设将通过以下方式进行检验 在远端呼吸道上皮细胞中MUC5B错误表达的背景下的肺泡上皮细胞消融策略 目的：明确肺泡上皮细胞凋亡在纤维化发生发展中的重要性。目标2将测试 在远端气道MUC5B增加的背景下诱导远端气道上皮细胞凋亡的假说 错误表达会促进小鼠蜂窝囊的形成。这一假设将通过使用远端呼吸道进行检验。 上皮细胞消融策略。AIM 2还将提供对远端呼吸道上皮细胞 MUC5B错误表达背景下的细胞凋亡和蜂窝囊形成间接导致肺泡 更替和纤维化。最后，目标3将检验预防肺泡和远端呼吸道的假设 即使在远端气道MUC5B错误表达增加的情况下，上皮细胞的凋亡也将阻止 持续性纤维化和蜂窝囊肿形成。虽然MUC5B在远端呼吸道的表达增加是一种风险 特发性肺间质纤维化和蜂窝囊肿发生的因素，目前对其基本情况知之甚少。 连接这些事件的机制。虽然与项目1和2广泛整合并充分利用 在核心资源方面，拟议研究的完成将改变对这些未研究的理解 问题，并对MUC5B如何促进发展这一悬而未决的问题提供了新的见解 在脆弱的肺中有间质纤维化和蜂窝状囊肿。

PROJECT SUMMARY The overall goal of Project 3 is to understand how increased misexpression of MUC5B in distal airways leads to honeycomb cyst formation, fibroblast accumulation, pro-fibrotic programming and ultimately fibrosis in response to distal airway and alveolar epithelial injury. Through a combination of in vivo studies in mouse models and in vitro studies with human lung epithelial cells and fibroblasts, Project 3 seeks to fill this knowledge gap by testing the hypothesis that MUC5B misexpression and persistent ER stress in distal airway epithelial cells creates susceptibility to apoptosis in both alveolar epithelial cells and distal airway epithelial cells leading to fibrosis and honeycomb cyst formation, respectively. We will address mechanistic questions about: (i) how MUC5B misexpression by distal airway epithelial cells creates vulnerability to apoptosis induction leading to fibroblast accumulation, pro-fibrotic programming, fibrosis and honeycomb cyst formation, (ii) the relative role(s) of alveolar and distal airway epithelial cell apoptosis in the development of fibrosis and honeycomb cysts, and (iii) from a remedial perspective, if prevention of epithelial cell apoptosis mitigates the development of pulmonary fibrosis and honeycomb cyst formation. While much has been learned about the role of alveolar epithelial cell apoptosis in the development of fibrosis, most of these studies were conducted prior to the discovery of increased IPF susceptibility conferred by MUC5B misexpression. Project 3 seeks to address this knowledge gap. Aim 1 will test the hypothesis that alveolar epithelial cell apoptosis, in the context of increased distal airway Muc5b misexpression, leads to fibrosis, but not honeycomb cyst formation in mice. This hypothesis will be tested using an alveolar epithelial cell ablation strategy in the context of Muc5b misexpression in distal airway epithelial cells to define the importance of alveolar epithelial cell apoptosis in the development of fibrosis. Aim 2 will test the hypothesis that induction of distal airway epithelial cell apoptosis in the context of increased distal airway Muc5b misexpression promotes honeycomb cyst formation in mice. This hypothesis with be tested using a distal airway epithelial cell ablation strategy. Aim 2 will also provide insight into the question of whether distal airway epithelial cell apoptosis and honeycomb cyst formation in the context of Muc5b misexpression indirectly leads to alveolar replacement and fibrosis. Lastly, Aim 3 will test the hypothesis that prevention of alveolar and distal airway epithelial cell apoptosis even in the context of increased distal airway Muc5b misexpression will prevent persistent fibrosis and honeycomb cyst formation. While increased MUC5B expression in distal airways is a risk factor for the development of fibrosis and honeycomb cysts in IPF patients, little is known about the fundamental mechanisms that connect these events. Though extensive integration with Projects 1 and 2 and full utilization of the Core resources, completion of the proposed studies will innovate understanding of these understudied questions and provide novel insights into the unresolved question of how MUC5B contributes to the development of interstitial fibrosis and honeycomb cysts in the vulnerable lung.