Therapeutic effect and underlying mechanism of exosomes from human adipose-derived stem cells on smoke-induced inflammation and lung injury in mice

Abstract

Objective To investigate the therapeutic effects of exosomes from human adipose-derived stem cells (hADSCs-Exos) on the inflammation and lung injury in mice with smoke-induced chronic obstructive pulmonary disease (COPD), and explore the underlying mechanism. Methods Exosomes were isolated from culture supernatant of hADSCs. A total of 24 male C57bl/6 mice were randomly divided into 3 groups (n=8 for each group), namely the control, COPD and exosomes-treated group, respectively. The mice of the latter 2 groups were exposed to cigarette smoke for 4 weeks to establish the COPD model. The exosomes-treated group received intratracheal instillation of 30 μL hADSCs-Exos (100 mg/L), while the control and COPD groups were treated with 30 μL PBS. Their body weights were monitored weekly for 4 weeks before being sacrificed. The concentrations of TNF-α, IL-6 and chemokine CXCL1 were detected by ELISA. The levels of pyroptosis-related proteins in the lungs like Caspase-1, ASC and NLRP3 were determined using immunofluorescence assay, and the expression levels of apoptosis-related proteins Bcl-2, Bax, Caspase-3 and Caspase-9 were measured by Western blotting. In addition, pathological abnormalities of the lungs and mucus secretion in the airway were observed after HE and PAS staining. Results Compared with the control group, the mice in the COPD group had lower body weight and higher concentrations of TNF-α, IL-6 and CXCL1, up-regulated expression of Caspase-1, ASC and NLRP3 but down-regulated level of Bcl-2 in the lungs, and those of Bax, Caspase-3 and Caspase-9 were increased (all P < 0.05). In comparison with the COPD group, the exosomes-treated group had higher body weight, lower levels of TNF-α, IL-6 and CXCL1, as well as down-regulated Caspase-1, ASC, NLRP2, Bax, Caspase-3 and Caspase-9, while the expression of Bcl-2 was increased (all P < 0.05). Histologically, lung tissues were severely damaged and pulmonary mucus secretion was obvious in the COPD group, whereas, the injuries were relieved with diminished mucus production in the exosomes-treated group. Conclusion hADSCs-Exos can alleviate smoke-induced inflammation, inhibit pyroptosis and apoptosis, reduce mucus secretion in lung tissues, and then thereby contribute to the repair of lungs in COPD.

Keywords

• exosomes from adipose-derived stem cells
• inflammation
• pyroptosis
• apoptosis
• mucus secretion
• lung injury