Lipopolysaccharide-induced active telocyte exosomes alleviate lipopolysaccharide-induced vascular barrier disruption and acute lung injury via the activation of the miRNA-146a-5p/caspase-3 signaling pathway in endothelial cells

Background Lipopolysaccharide (LPS)-induced apoptosis of lung microvascular endothelial cells (ECs) is the main reason of lung edema and acute lung injury (ALI) in septic conditions. Telocytes (TCs) are a distinct type of interstitial cells found around the lung microvasculature, which may protect ECs through the release of shed vesicles. However, whether TCs protect against LPS-induced EC apoptosis and ALI has not been determined. Methods The protective effects of TCs on ECs were assessed in vitro using transwell assays and flow cytometry, and in vivo using an LPS-induced mouse ALI model. RNA sequencing was used to identify miRNA-146a-5p as a key component of TC-derived exosomes. The functions of miRNA-146a-5p were further evaluated by western blotting, flow cytometry, and transendothelial electrical resistance measurements. Results We demonstrated that LPS stimulation induced the secretion of active exosomes from TCs, which inhibited LPS-mediated apoptosis of ECs and reduced ALI in mice. Moreover, miRNA-146a-5p was identified as the main bioactive molecule in TC-derived exosomes, capable of inhibiting LPS-induced caspase-3 activation and apoptosis in ECs. Conclusions Our results indicate that TCs effectively prevent LPS-induced EC apoptosis and ALI through the release of exosomes, with subsequent activation of the miRNA-146a-5p/caspase-3 signaling pathway in ECs.