Bone marrow mesenchymal stem cells-derived exosomes containing miR-539-5p inhibit pyroptosis through NLRP3/caspase-1 signalling to alleviate inflammatory bowel disease

Exosomes derived from bone mesenchymal stem cells (BMSCs) are potential candidates for inflammatory bowel disease (IBD) treatment. The present study investigated the therapeutic effect and potential mechanism of BMSCs-derived exosomes on pyroptosis in IBD.We induced IBD in mice and cell models through dextran sulfate sodium (DSS) and LPS, respectively. The mRNA and protein expression levels were assessed by qRT-PCR, Western blotting, IF and IHC. The concentrations of IL-1β, IL-18 and TNFα were assessed using ELISA. ROS levels were determined using DCFH-DA staining. Cell proliferation of mIECs was analysed using an MTT assay. In addition, a flow cytometry assay was performed to detect pyroptosis. Finally, the binding relationship between miR-539-5p and NLRP3 was verified by a dual luciferase reporter gene assay.Our results revealed that intraperitoneal injection of BMSCs-derived exosomes inhibited DSS-induced pyroptosis as well as IBD symptoms in mice. In addition, BMSCs-derived exosome treatment suppressed pyroptosis, ROS levels and the concentrations of proinflammatory cytokines (IL-1β, IL-18 and TNFα) in LPS-treated mIECs in a miR-539-5p-dependent manner. Further research found that miR-539-5p suppressed NLRP3 expression in mIECs by directly targeting NLRP3. As expected, pyroptosis in LPS-treated mIECs was significantly reduced by NLRP3 knockdown. In addition, NLRP3 silencing restored the inhibitory effect of exosomes derived from BMSCs transfected with miR-539-5p inhibitor on pyroptosis in LPS-treated mIECs.The present study demonstrated that BMSCs-derived exosomal miR-539-5p suppresses pyroptosis through NLRP3/caspase-1 signalling to inhibit IBD progression.