Exosomal miR-218 secreted from endothelial progenitor cells mitigates acute lung injury in sepsis mice by inhibiting HMGA1 in alveolar macrophages.

BACKGROUND AND

OBJECTIVE

Sepsis-related acute lung injury (S-ALI) had become an important public health issue worldwide. However, the mechanism of S-ALI was still not fully understood. This study aims to investigate the possibility of exosomes secreted from endothelial progenitor cells (EPCs) serving as a carrier for microRNA (miR)-218 to alleviate S-ALI and explore the possible mechanism.

METHODS

Exosomes were isolated from EPCs of C57BL/6J mice using differential centrifugation. Exosomes tracking in vivo and their uptake by EPCs in vitro were detected. miR-218 inhibitor and mimic were applied to investigate its function in mice and regulating polarization of alveolar macrophages (AMs). Bioinformatics and dual-luciferase reporter gene assays were used to explore the downstream targets of miR-218. si-HMGA1 and oe-HMGA1 were used to investigate its function in regulating polarization of AMs. Rescue experiments were carried out to uncover the interaction between miR-218 and HMGA1 in AMs.

RESULTS

Exosomes were isolated from EPCs and confirmed their accumulation in the mice lung as well as their uptake by AMs in vitro. In vivo, miR-218 transferred by exosomes secreted from EPCs mitigated ALI. In vitro, miR-218 inhibitor enhanced LPS-induced polarization of M1 macrophages, while miR-218 mimic suppressed these reactions. HMGA1 was confirmed as a target gene of miR-218, and its over-expression offset the protective effects of miR-218.

CONCLUSIONS

miR-218 transferred by exosomes secreted from EPCs mitigated ALI in septic mice by inhibiting HMHA1 which regulates macrophages polarization.