Fibronectin on the Surface of Extracellular Vesicles Mediates Fibroblast Invasion

Abstract

Extracellular vesicles (EVs) are endosome and plasma membrane-derived nano-sized vesicles that participate in intercellular signaling. Although EV cargo may signal via multiple mechanisms, how signaling components on the surface of EVs mediate cellular signaling is less well understood. In this study, we show that fibroblast-derived EVs carry fibronectin on the vesicular surface, as evidenced by mass spectrometry-based proteomics (Sequential Window Acquisition of all Theoretical Mass Spectra) and flow-cytometric analyses. Fibroblasts undergoing replicative senescence or transforming growth factor b1-induced senescence and fibroblasts isolated from human subjects with an agerelated lung disorder, idiopathic pulmonary fibrosis, secreted higher numbers of EVs than their respective controls. Fibroblast-derived EVs induced an invasive phenotype in recipient fibroblasts. This invasive fibroblast phenotype was dependent on EV surface localization of fibronectin, interaction with the fibronectin receptor a5b1 integrin, and activation of invasion-associated signaling pathways involving focal adhesion kinase and Src family kinases. EVs in the cellular supernatant, unbound to the extracellular matrix, were capable of mediating invasion signaling on recipient fibroblasts, supporting a direct interaction of EV surface fibronectin with the plasma membrane of recipient cells. Together, these studies uncover a novel mechanism of EV signaling of fibroblast invasion that may be relevant in the pathogenesis of fibrotic diseases and cancer.

Syndecan-1 promotes lung fibrosis by regulating epithelial reprogramming through extracellular vesicles

“…EVs isolated from fibrotic lungs promote lung fibrosis. Recent studies have found that EVs carry profibrotic mediators that have fibrogenic consequences in vitro (34)(35)(36)(37). However, no studies to date to our knowledge have determined the in vivo effects of EVs in lung fibrosis.…”

“…To this end, several studies reported EVs having a functional role in pulmonary diseases, such as acute lung injury, chronic obstructive pulmonary disease, and lung cancer (25)(26)(27)(28)(29)(30)(31). Only recently have studies begun unraveling the role that EVs play in mediating fibroproliferation (32)(33)(34)(35)(36)(37).…”

Transforming growth factor beta induces fibroblasts to express and release the immunomodulatory protein PD‐L1 into extracellular vesicles

“…Extracellular vessicles act as major channels in cell‐cell communication and PD‐L1 on EVs has been shown to mediate immune evasion and inhibit T cell functions . Moreover, recent studies have demonstrated (i) that in IPF there is an increased number of EVs which contribute to pulmonary fibrosis pathogenesis; and (ii) fibroblast‐derived EVs induce an invasive phenotype in recipient fibroblasts . Since TGFβ induced expression of the checkpoint inhibitor PD‐L1 which acted in a cell‐dependent/autocrine manner (Figures ), we investigated whether the expressed PD‐L1 was secreted into EVs; and if so, could such PD‐L1 act as a paracrine mediator of immune suppression and/or fibroblast migration.…”

“…Moreover, recent studies have demonstrated (i) that in IPF there is an increased number of EVs which contribute to pulmonary fibrosis pathogenesis 25 ; and (ii) fibroblast-derived EVs induce an invasive phenotype in recipient fibroblasts. 53 Since TGFβ induced expression of the checkpoint inhibitor PD-L1 which acted in a cell-dependent/autocrine manner (Figures 1-5), we investigated whether the expressed PD-L1 was secreted into EVs; and if so, could such PD-L1 act as a paracrine mediator of immune suppression and/or fibroblast migration. To address these questions, we isolated EVs from TGFβ stimulated MRC5 cells and determined that PD-L1 was expressed on EVs of comparable size and concentration ( Figure 6A,B).…”

Unique Protein Profiles of Extracellular Vesicles as Diagnostic Biomarkers for Early and Advanced Non‐Small Cell Lung Cancer

“…Chanda et al. examined the action of EVs in fibroblast invasion, and discovered the FAK and Src family kinase stimulated by fibronectin are responsible for EVs‐mediated fibroblast invasion . Our bioinformatics analysis also indicated that proteins associated with the fibronectin‐integrin pathway were elevated.…”