Conclusions
Increased EVs function as carriers for signaling mediators, such as WNT5A, in IPF and thus contribute to disease pathogenesis. Characterization of EV secretion and composition may lead to novel approaches to diagnose and develop treatments for pulmonary fibrosis.
Methods
We isolated EVs from BAL fluid (BALF) from experimental lung fibrosis as well as samples from IPF, non-IPF interstitial lung disease (ILD), non-ILD, and healthy volunteers from two independent cohorts. EVs were characterized by transmission electron microscopy, nanoparticle tracking analysis, and Western blotting. Primary human lung fibroblasts (phLFs) were used for EV isolation and analyzed by metabolic activity assays, cell counting, quantitative PCR, and Western blotting upon WNT gain- and loss-of-function studies.Measurements and Main
Results
We found increased EVs, particularly exosomes, in BALF from experimental lung fibrosis as well as from patients with IPF. WNT5A was secreted on EVs in lung fibrosis and induced by transforming growth factor-β in primary human lung fibroblasts. The phLF-derived EVs induced phLF proliferation, which was attenuated by WNT5A silencing and antibody-mediated inhibition and required intact EV structure. Similarly, EVs from IPF BALF induced phLF proliferation, which was mediated by WNT5A.Conclusions: Increased EVs function as carriers for signaling mediators, such as WNT5A, in IPF and thus contribute to disease pathogenesis. Characterization of EV secretion and composition may lead to novel approaches to diagnose and develop treatments for pulmonary fibrosis.