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?

摘要 这项研究的总体目标是了解MUC 5 B的表达增强是如何影响MUC 5 B的表达的。 导致上皮细胞损伤和肺纤维化。在过去的十年里，我们发现：1）收益- MUC 5 B启动子功能缺失变体rs35705950是IPF发展的主要风险因素， 已被多个独立研究者验证; 2）在IPF患者中，MUC 5 B错误表达 在细支气管和肺泡上皮2型（AEC 2）细胞中; 3）来自远端气道（<2 mm气道）的IPF上皮 caliber）在体外具有独特的迁移性、促纤维化表型，其在暴露于 博来霉素;和4）MUC 5 B似乎参与IPF的发病机制，并且MUC 5 b的浓度 与博莱霉素诱导的小鼠肺纤维化直接相关。尽管有这些发现，我们并不完全理解 远端肺中过量的MUC 5 B是如何与肺纤维化的发展机制相关的。我们 初步研究结果结合内质网（ER）应激与 IPF和肺纤维化的实验模型，以及最近观察到的XBP 1（S）似乎是 对于MUC 5 B启动子变体诱导的MUC 5 B表达是必要的和足够的，表明虽然 MUC 5 B过表达通过引起持续的稳态ER使个体处于发展IPF的风险中 细支气管上皮细胞的应激、成纤维细胞募集和促纤维化程序需要二次打击（例如 老化、烟草烟雾和/或炎症）导致细支气管上皮细胞的有害ER应激， 成纤维细胞的募集和活化。因此，我们假设MUC 5 B过表达可能与MUC 5 B的表达有关。 细支气管上皮引起稳态ER应激，引发对随后损伤的反应，从而 导致有害的内质网应激反应的持续激活， 在损伤/修复过程中并导致成纤维细胞活化。在目标1中，我们将表征气道上皮细胞 最易受突变体诱导的MUC 5 B过表达和ER应激影响的人群，并绘制这些 表达变化对IPF肺纤维化异质性和MUC 5 B启动子变异的影响， ER应激、UPR、自噬、细胞衰老和凋亡之间的关系。在目标2中，我们将使用体外 测试MUC 5 B和ER应激对气道上皮细胞生物物理特性的作用的实验模型 和上皮细胞驱动的成纤维细胞活化。在目标3中，我们将使用Muc 5 b和Xbp 1（S）过表达模型， 以及在基线（首次命中）和响应于 老化和/或博来霉素（第二次命中）以研究Muc 5 b、ER应激和肺纤维化之间的关系。 这项研究将解决一个关于IPF病理生物学的关键问题： MUC 5 B促进上皮损伤和肺纤维化？