The matrix-fibroblast interplay contributes to HIF-1 alpha pathway activation: a possible therapeutic target in idiopathic pulmonary fibrosis (IPF)

Background and Objective: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with poor prognosis. Activated fibroblasts are key effector cells in fibrosis. Like in cancer, the microenvironment plays an important role in IPF progression. Whether the ECM conditioned by IPF fibroblasts determines the phenotype of naive fibroblasts is difficult to explore. Methods: IPF-derived primary human lung fibroblasts (HLFs) were cultured on Matrigel and then cleared using NH4OH, thus creating the IPF-conditioned matrix (IPF-CM). Normal HLF-CM served as control. HLFs were then cultured on these CMs. Cell count, viability, distribution, Matrix Metallo-Proteinases (MMP) activity and RNA-seq for gene expression were tested. The effects of the anti-fibrotic drugs (nintedanib and pirfenidone) at physiologically relevant concentrations were analyzed. Results: Normal fibroblasts cultured on IPF-CM arranged in large aggregates as a result of increased proliferation, migration and differentiation (e.g. elevated Collagen1a and alpha-SMA). Both drugs effectively blocked the large aggregate formation induced by the IPF-CM (p Conclusion: IPF fibroblasts alter the extracellular matrix, thus creating a matrix that further propagates an IPF-like phenotype in normal HLFs. This assay demonstrated differences in drug activities for approved IPF drugs at clinically relevant concentrations. Thus, the matrix–fibroblast interplay might serve as a relevant assay to explore drug candidates for IPF treatment.