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.
Idiopathic Pulmonary fibrosis (IPF), a devastating form of interstitial lung disease in adults, is marked by progressive scarring of lung tissue, respiratory failure, and death for which there is a significant unmet need for effective medical therapies. To overcome one of the current barriers in IPF research (a dearth of preclinical models) and to facilitate a better understanding of the fibrotic processes for the identification of new therapeutic targets, we developed two novel mouse models expressing mutations in the Surfactant Protein C (SP-C) gene that are associated with an IPF like syndrome in humans. These highly relevant preclinical models used in conjunction with human IPF lung and serum samples will serve as a comprehensive preclinical platform to identify cell populations, signaling pathways, biomarkers, and the contributions of age and sex on IPF development towards the goal of accelerating the discovery of new IPF treatments.
