Exosomal miR-221-3p derived from bone marrow mesenchymal stem cells alleviates asthma progression by targeting FGF2 and inhibiting the ERK1/2 signaling pathway

Abstract Exosomes derived from human bone marrow mesenchymal stem cells (BMSCs) play potential protective roles in asthma. However, the underlying mechanisms remain not fully elucidated. Herein, exosomes were isolated from BMSCs, and their morphology, particle size and exosome marker proteins were identified by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) and Western blot, respectively. Then airway smooth muscle cells (ASMCs) were treated with transforming growth factor-β1 (TGF-β1) to construct proliferation model, and then incubated with BMSCs-derived exosomes. We found that exosome incubation increased miR-221-3p expression, and inhibited proliferation, migration, and the levels of extracellular matrix (ECM) proteins including fibronectin and collagen III. Moreover, FGF2 was identified as a target gene of miR-221-3p. FGF2 overexpression reversed the inhibitory effects of exosomal miR-221-3p on ASMC progression. Besides, the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2) is inhibited by exosomal miR-221-3p, which was reversed by FGF2 overexpression. And ERK1/2 signaling activator reversed the effects of exosomal miR-221-3p on ASMC progression. Additionally, an ovalbumin (OVA)-induced asthmatic mice model was established, and exosomes treatment alleviated airway hyper-responsiveness (AHR), histopathological damage and ECM deposition in asthmatic mice. Taken together, our findings indicated that exosomal miR-221-3p derived from BMSCs inhibited FGF2 expression and the ERK1/2 signaling, thus attenuating proliferation, migration and ECM deposition in ASMCs and alleviating asthma progression in OVA-induced asthmatic mice. Our findings may provide a novel therapeutic strategy for asthma.