RESUMO
Objective To investigate the protective role and underlying mechanism of human dental pulp stem cells (DPSCs)-derived exosomes against lipopolysaccharide ( LPS) induced acute lung injury ( ALI) in pulmonary alveolar macrophage(PAM) cells of rats.Methods DPSCs were cultured in the complete culture medium , and their supernatants at passage 6 were collected after serum-free medium treatment for 24 hours.Exosomes were extracted and purified with ultracentrifugation .Rat PAM NR8383 was cultured in 12-well plate and treated with LPS of 1μg/ml alone or together with exosomes.The supernatants were then collected at 0, 6, 12 and 24 h respectively after treatment .Inflammatory cytokine levels of tumor necrosis factor-α(TNF-α)and interleukins (IL-1βand IL-6) in the supernatant were measured by ELISA assay and the expression and phosphorylation level of MAPK (p44/42), NF-κB and IκBαin cell lysates were detected with Western-blotting.Results Compared with control group , the content of TNF-α,IL-1βand IL-6 increased significantly in LPS group (P<0.05), which indicated that the inflammatory cell model was induced successfully .The levels of TNF-αand IL-1βwere obviously attenuated after a high doses of exosomes treatment (P<0.05), and the expression of IL-6 was markedly suppressed after low and high doses of exosomes treatment (P<0.05), compared with the group of LPS treatment alone.The phosphorylation of NF-κB, IκBαand p44/42 was significantly inhibited after treatment with the DPSCs-derived exosomes.Conclusion DPSCs-derived exosomes may have a potential protective effect on LPS-induced ALI, and the underlying mechanism is that the activity of MAPK (p44/42) and NF-κB/IκBαpathways are eliminated by DPSCs-derived exosomes.