Lsc Abstract - Non-Canonical Wnt Signaling Is Mediated By Extracellular Vesicles In Pulmonary Fibrosis

Objective: Idiopathic pulmonary fibrosis (IPF) is a lethal lung disease of unknown etiology characterized by epithelial injury, myofibroblast activation, and extracellular matrix deposition. Reactivation of WNT/β-catenin pathway has been linked to the disease; however, the role of non-canonical WNT signaling has not been explored in detail. Recently, it has been shown that WNT ligands can be secreted on extracellular vesicles (EVs), which are known to regulate intercellular communication. We hypothesize that WNTs contribute via EVs to impaired cellular crosstalk in pulmonary fibrosis (PF). Methods and results: First, we performed a comprehensive profiling of EVs in experimental and human PF. EVs were isolated by ultracentrifugation from bronchoalveolar lavage (BAL) and characterized by electron microscopy, Western Blot and nanoparticle tracking analysis. Notably, we found increased EV secretion in BAL from murine and human PF. Additionally, the non-canonical WNT ligand WNT5A was upregulated in lung homogenates of PF and strongly enriched in fibrotic EVs. Moreover, CD81-derived EVs were increased in human PF BALF, suggesting fibroblasts as a potential source. Indeed, WNT5A was increased in EVs from TGFβ-treated primary human lung fibroblasts. WNT5A potentiated profibrotic TGFβ-signaling in lung epithelial A549 cells via induction of collagen1a1 and monocyte chemotactic protein, both of which have been linked to PF. Conclusions: EVs are increased in experimental and human PF and contain disease-specific proteins. EVs contribute to impaired cell-cell communication by profibrotic TGFβ-driven non-canonical WNT5A signaling and thus represent potential targets for new therapies in IPF. This abstract has been presented previously at the European Respiratory Society9s Lung Science Conference in March 2016 .