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）是老年人的一种破坏性间质性肺病（ILD）， 通过破坏远端肺结构，最终导致瘢痕形成、异常气体交换，以及 呼吸衰竭开发更好的IPF治疗结局的一个关键障碍是缺乏 临床前相关模型。基于最近的范式转变，其中重复的概念 对功能障碍、脆弱的肺泡上皮的损伤以及异常的伤口愈合反应， 作为疾病“驱动因素”，IPF治疗发现的新机会正在出现。突变 肺泡2型细胞（AT 2）限制性表面活性蛋白C（SP-C）基因（SFTPC）已在 为了解IPF发病机制提供了重要线索。解决 由于IPF患者的需求未得到满足，因此该提案建立在我们先前工作的坚实基础之上， SP-C生物合成的细胞生物学，最终产生了两种新的基因敲入小鼠模型， 自发性肺纤维化已经在进行中，其在AT 2细胞中以等位基因表达临床SP-C突变， 诱导方式我们已发表的数据表明，临床IPF相关SFTPC突变 产生异常的SP-C前蛋白同种型，在功能上分离为2种AT 2表型：ER应激 由细胞内SP-C错误折叠（BRICHOS）或proSP-C受损的自噬/线粒体自噬诱导 非天然细胞器（Non-BRICHOS）。当在体内肺上皮中表达时， 非BRICHOS突变体（SftpcI 73 T）和BRICHOS突变体（SftpcC 121 G）对肺具有极强的毒性， 每一种都足以引起时间依赖性的、生理限制性的外周纤维化肺表型， 阐述了人类IPF中报告的预防相关生物标志物。该提案将利用这些独特的 用于探索、目标识别/验证和概念验证研究的模型，旨在绘制细胞 亚群和发现新的途径驱动肺纤维化，同时提供一个引人注目的翻译 与该U 01联盟中的其他临床前/转化平台对接的平台，以加速IPF 治疗发展在3个具体目标中，我们提出利用Sftpc突变小鼠来绘制细胞群， 自发性肺纤维化演变过程中出现的转录组学特征和细胞间串扰谱 表型[具体目标1]，鉴定在研究期间阐述的新的疾病相关生物标志物候选物。 异常损伤修复过程[具体目标2]，并评估的重要贡献和机制， 年龄和性别影响IPF表型[具体目标3]。重要的是， Sftpc模型将使用来自良好表型的肺组织和血清进行交叉验证和情境化。 人IPF生物库。完成后，该项目产生的有影响力的可交付成果将包括 一个新的平台，可以更好地了解IPF从发病到疾病进展的发病机制，并作为一个 为更广泛的研究社区提供资源，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.