Molecular characterization of a precision-cut rat lung slice model for the evaluation of antifibrotic drugs.

The translation of novel pulmonary fibrosis therapies from preclinical models into the clinic represents a major challenge demonstrated by the high attrition rate of compounds that showed efficacy in preclinical models but demonstrated no significant beneficial effects in clinical trials. A precision-cut lung tissue slice (PCLS) contains all major cell types of the lung and preserves the original cell-cell and cell-matrix contacts. It represents a promising ex vivo model to study pulmonary fibrosis. In this study, using RNA sequencing, we demonstrated that transforming growth factor-β1 (TGFβ1) induced robust fibrotic responses in the rat PCLS model, as it changed the expression of genes functionally related to extracellular matrix remodeling, cell adhesion, epithelial-to-mesenchymal transition, and various immune responses. Nintedanib, pirfenidone, and sorafenib each reversed a subset of genes modulated by TGFβ1, and of those genes we identified 229 whose expression was reversed by all three drugs. These genes define a molecular signature characterizing many aspects of pulmonary fibrosis pathology and its attenuation in the rat PCLS fibrosis model. A panel of 12 genes and three secreted biomarkers, including procollagen I, hyaluronic acid, and WNT1-inducible signaling pathway protein 1 were validated as efficacy end points for the evaluation of antifibrotic activity of experimental compounds. Finally, we showed that blockade of α _V -integrins suppressed TGFβ1-induced fibrotic responses in the rat PCLS fibrosis model. Overall, our results suggest that the TGFβ1-induced rat PCLS fibrosis model may represent a valuable system for target validation and to determine the efficacy of experimental compounds.