Modeling cell-cell interactions to advance drug discovery in Idiopathic Pulmonary Fibrosis
BackgroundIdiopathic Pulmonary Fibrosis (IPF) is characterized by scarring and remodeling of lung tissue, leading to progressive pulmonary dysfunction. Currently, very little is known about the steps involved in disease initiation and progression because models of IPF poorly replicate these processes. However, understanding the pathogenesis of IPF is essential for developing effective therapies. To address this, we have developed a scaffold-based co-culture IPF organoid that uses healthy and diseased human primary and iPSC-derived alveolar epithelial cells and fibroblasts to recapitulate the cellular communication and cell fate during progressive fibrosis. MethodsWe generated microbead scaffolds that mimic alveolar air-sacs and coated them in a rotating bioreactor with primary lung fibroblasts and induced pluripotent stem cell-derived type 2 alveolar cells (iAT2s). iAT2s with the surfactant protein C (SFTPC) I73T variant and the syngeneic corrected control iAT2s were cultured with primary healthy and IPF fibroblasts in different combinations. The epithelial-mesenchymal interactions during fibrosis initiation and progression were evaluated by single-cell RNA sequencing. ResultsWe found that the interaction between epithelial cells and fibroblasts plays a key role in inducing fibrotic responses in this model, with the secretion of chemokines, cytokines, TGF{beta}, and matrix metalloproteinases that mirror those observed in the serum of patients with pulmonary fibrosis. Single-cell RNA sequencing revealed the emergence of many cell subtypes observed in progressive lung fibrosis, along with key cellular interactions that correlated with the initial upregulation of fibrosis pathways, extracellular matrix (ECM) remodeling, inflammation, and changes in lipid metabolism. The anti-fibrotic compounds, Nintedanib and the TGF{beta} inhibitor, SB431542, demonstrated dose-dependent efficacy in the model, with IC50 values comparable to those observed in the clinic, and significantly reduced secretion of fibrosis-related factors. ConclusionOverall, this study shows that the three-dimensional, reductionist, cell co-culture organoid effectively models several components of progressive lung fibrosis, facilitating the investigation of epithelial-mesenchymal interactions and serving as a patient-relevant model to better predict the efficacy of therapeutics in the clinic.