HMSCs exosome‐derived miR‐199a‐5p attenuates sulfur mustard‐associated oxidative stress via the CAV1/NRF2 signalling pathway

Sulfur mustard (SM) is a blister‐producing chemical warfare agent which could lead to a cascade of systemic damage, especially severe acute lung injury. Oxidative stress is considered to be vital processes for the SM toxicity mechanism. We previously proved the therapeutic effect of exosomes derived from bone marrow mesenchymal stromal cells in promoting the repair of alveolar epithelial barrier and inhibiting apoptosis. However, the key functional components in exosomes and the underlying mechanisms have not been fully elaborated. This research shed light on the function of the key components of human umbilical cord mesenchymal stem cell‐derived exosomes (HMSCs‐Ex). We noted that HMSCs‐Ex‐derived miR‐199a‐5p played a vital role in reducing pneumonocyte oxidative stress and apoptosis by reducing reactive oxygen species, lipid peroxidation products and increasing the activities of antioxidant enzymes in BEAS‐2B cells and mouse models after exposure to SM for 24 h. Furthermore, we demonstrated that the overexpression of miR‐199a‐5p in HMSCs‐Ex treatment induced a further decrease of Caveolin1 and the activation of the mRNA and protein level of NRF2, HO1 and NQO1, compared with HMSCs‐Ex administration. In summary, miR‐199a‐5p was one of the key molecules in HMSCs‐Ex that attenuated SM‐associated oxidative stress via regulating CAV1/NRF2 signalling pathway.