Endoplasmic reticulum stress in MUC5B-driven lung fibrosis

MUC5B驱动的肺纤维化中的内质网应激

• 批准号: 10627599
• 负责人: David Albert Schwartz
• 金额: $ 64.06万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2028-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10627599
• 关键词: Affect; Aging; Apoptosis; Autophagocytosis; Biopsy; Bleomycin; Bronchioles; Caliber; Cell Aging; Cell Mobility; Cell Proliferation; Cells; Development; Differentiation Antigens; Distal; Epithelial Cells; Epithelium; Etiology; Event; Experimental Models; Exposure to; Fibroblasts; Fibrosis; Functional disorder; Genetic; Genetic Transcription; Goals; Heterogeneity; Immunofluorescence Immunologic; In Situ Hybridization; In Vitro; Individual; Inflammation; Injury; Link; Lung; Lung diseases; MUC5B gene; Maps; Modeling; Mucins; Mus; Operative Surgical Procedures; Pathogenesis; Pathogenicity; Pathologic; Pathway interactions; Patients; Pattern; Phenotype; Polymers; Population; Predisposition; Production; Proteins; Pulmonary Fibrosis; Research; Research Personnel; Risk; Risk Factors; Role; Structure of parenchyma of lung; Testing; Tobacco smoke; Transgenic Mice; Variant; XBP1 gene; airway epithelium; alveolar epithelium; arm; biological adaptation to stress; biophysical properties; cell injury; endoplasmic reticulum stress; epithelial injury; gain of function; in vivo; injury and repair; innovation; lung development; lung injury; novel strategies; overexpression; pharmacologic; prevent; promoter; proteostasis; recruit; response; response to injury; tissue repair; transcriptome sequencing; transcriptomics; wound healing

ABSTRACT The overall goal of the proposed research is to understand how enhanced expression of MUC5B contributes to epithelial cell injury and lung fibrosis. Over the past decade, we have found that: 1) a gain- of-function MUC5B promoter variant rs35705950 is the dominant risk factor for the development of IPF which has been validated by multiple independent investigators; 2) among patients with IPF, MUC5B is misexpressed in bronchioles and alveolar epithelial type 2 (AEC2) cells; 3) IPF epithelia from distal airways (<2 mm airway caliber) have a unique migratory, pro-fibrotic phenotype in vitro that is replicated ex vivo in mice exposed to bleomycin; and 4) MUC5B appears to be involved in the pathogenesis of IPF, and the concentration of Muc5b is directly related to bleomycin-induced lung fibrosis in mice. Despite these findings, we don’t fully understand how excess MUC5B in the distal lung is mechanistically linked to the development of pulmonary fibrosis. Our preliminary findings combined with the established association between endoplasmic reticulum (ER) stress and both IPF and experimental models of lung fibrosis, and the recent observation that XBP1(S) appears to be necessary and sufficient for MUC5B expression induced by the MUC5B promoter variant, suggest that while overexpression of MUC5B places individuals at risk of developing IPF by causing persistent homeostatic ER stress of bronchiolar epithelia, fibroblast recruitment and pro-fibrotic programming requires second hits (such as aging, tobacco smoke, and/or inflammation) resulting in detrimental ER stress of bronchiolar epithelia and recruitment and activation of fibroblasts. Accordingly, we hypothesize that MUC5B overexpression in bronchiolar epithelia causes homeostatic ER stress that primes responses to subsequent injury, thereby leading to persistent activation of detrimental ER stress responses that cause epithelial dysfunction during injury/repair and lead to fibroblast activation. In Aim 1, we will characterize the airway epithelial cell populations most susceptible to variant-induced MUC5B overexpression and ER stress and map these expression changes to the heterogeneity of lung fibrosis in IPF and the MUC5B promoter variant, examining the relationship between ER stress, UPR, autophagy, cell senescence, and apoptosis. In Aim 2, we will use in vitro experimental models to test the role of MUC5B and ER stress on the biophysical properties of airway epithelia and epithelial-driven activation of fibroblasts. In Aim 3, we will use Muc5b and Xbp1(S) overexpression models, and pharmacologic and genetic IRE1 pathway inhibition approaches at baseline (first hit) and in response to aging and/or bleomycin (second hits) to investigate the relationship between Muc5b, ER stress, and lung fibrosis. This research will address a crucial question about the pathobiology of IPF: How does enhanced expression of MUC5B promote epithelial injury and lung fibrosis?

抽象的 拟议研究的总体目标是了解MUC5B表达的增强 导致上皮细胞损伤和肺纤维化。在过去的十年中，我们发现：1）收益 - 功能MUC5B启动子变体RS35705950是IPF发展的主要风险因素 已由多个独立研究人员验证； 2）在IPF患者中，MUC5B是MISEXPESSSPESS的 在细胞支气管和肺泡上皮2型（AEC2）细胞中； 3）远端气道的IPF上皮（<2 mm气道 口径）在体外具有独特的迁移性，纤维化表型，在暴露于小鼠的小鼠中被复制 博来霉素； 4）MUC5B似乎参与IPF的发病机理，MUC5B的浓度 与博来霉素诱导的小鼠肺纤维化直接相关。尽管有这些发现，我们不完全了解 远端肺中的MUC5B如何与肺纤维化的发展有关。我们的 初步发现，结合了内质网（ER）应力与 肺纤维化的IPF和实验模型，以及最近的观察结果，即XBP1似乎是 MUC5B启动子变体诱导的MUC5B表达所必需的，足以表明 MUC5B的过表达使个人通过导致持续的稳态ER有可能发展IPF的风险 支气管上皮，成纤维细胞募集和促纤维化编程的压力需要第二次命中（例如 衰老，烟草烟雾和/或炎症），导致支气管上皮的有害ER应力和 成纤维细胞的募集和激活。根据，我们假设MUC5B过表达 支气管上皮引起的稳态ER压力，素质会对随后的损伤产生反应 导致持续激活有害的ER应力反应，引起上皮功能障碍 在受伤/修复过程中并导致成纤维细胞激活。在AIM 1中，我们将表征气道上皮细胞 种群最容易受到变体诱导的MUC5B过表达和ER应力，并将其绘制 IPF和MUC5B启动子变体中肺纤维化异质性的表达变化，检查了 ER应力，UPR，自噬，细胞感应和凋亡之间的关系。在AIM 2中，我们将在体外使用 测试MUC5B和ER应力对气道上皮生物物理特性的作用的实验模型 和上皮驱动的成纤维细胞激活。在AIM 3中，我们将使用MUC5B和XBP1（S）过表达模型， 以及在基线时（首次命中）的药理学和遗传IRE1途径抑制方法，并响应于 衰老和/或博来霉素（第二次命中），以研究MUC5B，ER应激和肺纤维化之间的关系。 这项研究将解决有关IPF病理生物学的关键问题：如何增强表达 MUC5B促进上皮损伤和肺纤维化？