Surfactant Protein C Mouse Models: A Fit For Purpose Preclinical Platform For Advancing Discovery In And Treatment Of Idiopathic Pulmonary Fibrosis

摘要 特发性肺纤维化(IPF)是一种以老年人为特征的破坏性间质性肺疾病(ILD) 通过破坏远端肺结构，最终导致疤痕形成，异常气体交换，以及 呼吸衰竭。开发IPF更好的治疗结果的一个关键障碍是缺乏 翻译相关的临床前模型。基于最近的范式转变，其中重复的概念 对功能失调、脆弱的肺泡上皮的损伤伴随着异常的伤口愈合反应 被认为是疾病“驱动力”的IPF正在出现新的治疗发现机会。基因突变 肺泡2型细胞(AT2)限制性表面活性蛋白C[SP-C]基因[SFTPC]已在 散发性和家族性IPF的发生，为了解IPF发病机制提供了重要线索。要解决这个问题 对于IPF患者未得到满足的需求，此建议建立在我们先前工作的坚实基础上，该工作描述了 SP-C生物合成的细胞生物学，最终产生两种新的敲入小鼠模型 自发性肺纤维化已经存在，在AT2细胞中表达临床SP-C突变的等位基因和 诱人的时尚。我们公布的数据表明，临床上IPF与SFTPC突变相关 产生异常的SP-C前蛋白亚型，在功能上分离为两个AT2表型：内质网应激 由细胞内SP-C错误折叠(Brichos)或自噬/有丝分裂吞噬功能受损所致 对非天然细胞器的错误处理(非Brichos)。在活体肺上皮细胞中表达时，两者 非Brichos突变体(SftpcI73T)和Brichos突变体(SftpcC121G)对肺和 每种都足以引起一种时间依赖的、生理上受限的外周纤维性肺表型， 阐述了在人类IPF中报告的翻译相关生物标志物。这项提议将利用这些独特的 旨在映射单元的发现、目标ID/验证和概念验证研究的模型 亚群和发现导致肺纤维化的新途径，同时提供引人注目的翻译 与该U01联盟中的其他临床前/转换平台对接的平台，以加速IPF 治疗方面的发展。在三个具体目标中，我们建议利用Sftpc突变小鼠来定位细胞群体， 自发性纤维化肺演变过程中的转录谱和细胞-细胞串扰谱 表型[具体目标1]，确定新的疾病相关生物标志物候选对象 异常损伤-修复过程[具体目标2]，并评估 哪些年龄和性别影响IPF表型[具体目标3]。重要的是，中定义的许多端点 Sftpc模型将使用来自表型良好的肺组织和血清进行交叉验证和背景分析。 人类IPF生物储存库。完成后，该项目产生的有影响力的交付成果将包括 新的平台，更好地了解IPF从发病到疾病发展的发病机制，并作为 为更广泛的研究界提供资源，以确定和测试治疗这种疾病的新疗法。

ABSTRACT Idiopathic Pulmonary fibrosis (IPF) is a devastating interstitial lung disease (ILD) of older adults characterized by disruption of distal lung architecture that ultimately leads to scar formation, abnormal gas exchange, and respiratory failure. A key barrier to developing better therapeutic outcomes for IPF has been a dearth of translationally relevant preclinical models. Based on a recent paradigm shift wherein the concepts of repetitive injury to a dysfunctional, vulnerable, alveolar epithelium coupled with an abnormal wound healing response are postulated as disease “drivers”, new opportunities are emerging for therapeutic discovery in IPF. Mutations in the alveolar type 2 cell (AT2) restricted, Surfactant Protein C [SP-C] gene [SFTPC], have been found in sporadic and familial IPF and provide important clues for understanding IPF pathogenesis. To address the unmet need for IPF patients, this proposal builds upon on a strong foundation of our prior work characterizing the cell biology of SP-C biosynthesis that culminated in generation of two novel knock-in mouse models of spontaneous lung fibrosis already in hand which express clinical SP-C mutants in AT2 cells in an allelic and inducible fashion. Our Published Data has demonstrated that clinical IPF associated SFTPC mutations produce aberrant SP-C proprotein isoforms that functionally segregate into 2 AT2 phenotypes: ER stress induced by intracellular SP-C misfolding (BRICHOS) or autophagy/mitophagy impaired from proSP-C mistrafficking to non-native organelles (Non-BRICHOS). When expressed in the lung epithelium in vivo, both the non-BRICHOS mutant (SftpcI73T) and the BRICHOS mutant (SftpcC121G) are extremely toxic to the lung and each is sufficient to evoke a time-dependent, physiologically restrictive peripheral fibrotic lung phenotype that elaborates translationally relevant biomarkers reported in human IPF. This proposal will leverage these unique models for Discovery, Target ID/ Validation, and Proof of Concept studies aimed at mapping cell subpopulations and uncovering novel pathways driving lung fibrosis whilst providing a compelling translational platform to interface with other preclinical/translational platforms in this U01 consortium to accelerate IPF therapeutic development. In 3 specific aims, we propose to utilize Sftpc mutant mice to map cell populations, transcriptomic profiles, and cell-cell crosstalk repertoires arising during evolution of spontaneous fibrotic lung phenotypes [Specific Aim 1], identify novel disease relevant biomarker candidates elaborated during the aberrant injury-repair process [Specific Aim 2], and assess the important contributions of and mechanisms by which aging and sex impact IPF phenotypes [Specific Aim 3]. Importantly, many of the endpoints defined in Sftpc models will be cross-validated and contextualized using lung tissue and serum from a well-phenotyped human IPF biorepository. When completed, the impactful deliverables produced from this project will include a new platform to better understand IPF pathogenesis from its onset through disease progression and serve as a resource for the broader research community to identify and test novel therapies to treat this disease.