Dendritic cells and M2 macrophage play an important role in suppression of Th2-mediated inflammation by adipose stem cells-derived extracellular vesicles

Although stem cell-derived extracellular vesicles (EVs) have been shown to facilitate regeneration of injured tissue, there is no report that evaluates the immune-modulating effect of stem cell-derived EVs on Th2-mediated inflammation. In this study, we evaluated the immunomodulatory effects of adipose stem cells (ASCs)-derived EVs on Th2-mediated inflammation induced by Aspergillus protease antigen in lung epithelial cells. The EVs were isolated from supernatant of ASCs and the diameters of EVs were measured by using dynamic light scattering. The mice primary lung epithelial cells and mouse lung epithelial cell line (MLE12) were pre-treated with 200 ng/ml of Aspergillus protease and then treated with 1 μg/ml of ASC-derived EVs. Real time PCR was performed to determine the expression levels of eotaxin, IL-25, TGF-β, and IL-10 mRNAs after EV treatment. To evaluate the role of EVs in macrophage polarization and dendritic cells (DCs) differentiation, in vitro bone marrow-derived macrophage and DCs stimulation assay was performed. EV treatment significantly decreased the expression of eotaxin and IL-25 and increased TGF-β and IL-10 in both lung epithelial cells. EV treatment significantly increased the expression of co-stimulatory molecules such as CD40, CD80, and CD 86 in immature DCs. Furthermore, EV treatment significantly enhanced the gene expression of M2 macrophage marker such as Arg1, CCL22, IL-10, and TGF-β. In conclusion, EVs of ASCs ameliorated Th2-mediated inflammation induced by Aspergillus protease antigen through the activation of dendritic cells and M2 macrophage, accompanied by down-regulation of eotaxin and IL-25, and up-regulation of TGF-β and IL-10 in mouse lung epithelial cells. Keywords: Mesenchymal stromal cells, Extracellular vesicles, Immunosuppression, Macrophages, Dendritic cells, Transforming growth factor beta, Interleukin-10