Hypoxia-preconditioned mesenchymal stromal cell-derived exosomes attenuate LPS-induced acute lung injury and early epithelial remodeling in mice: evidence for a miR-486a-5p-Skp2-GATA4 axis.

Abstract

<h4>Background</h4>Acute lung injury (ALI) can initiate early epithelial remodeling that may precede pulmonary fibrosis, with EMT of alveolar epithelial cells implicated in this acute phase. While mesenchymal stromal cell (MSC)-derived exosomes exhibit repair potential, their conventional culture conditions fail to mimic the hypoxic microenvironment of ALI. Here, we explored the therapeutic effects and regulatory mechanisms of hypoxia-preconditioned bone marrow MSC-derived exosomes (HExos) in LPS-induced ALI with early epithelial remodeling.<h4>Methods</h4>BMSCs were characterized via osteogenic/adipogenic differentiation and flow cytometry. Exosomes derived under normoxia (NExos) and hypoxia (HExos) were isolated and validated using nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and Western blot. An LPS-induced ALI mouse model was employed to evaluate exosome efficacy. Through integrated miRNA sequencing, luciferase reporter assays, and gain-/loss-of-function experiments, we examined a working model involving the miR-486a-5p/Skp2/GATA4 axis.<h4>Results</h4>HExos markedly alleviated LPS-induced acute lung injury and early-stage collagen deposition. Mechanistically, HExos were enriched with miR-486a-5p, which directly targeted Skp2, thereby reducing Skp2-mediated ubiquitin-proteasome degradation of GATA4 and attenuating EMT-like changes. Notably, miR-486a-5p mimics reversed EMT-like changes in alveolar epithelial cells, while its knockdown abolished the protective effect.<h4>Conclusions</h4>Hypoxia-preconditioned bone marrow-derived mesenchymal stromal cell (BMSC) exosomes demonstrate significant potential to alleviate LPS-induced acute injury and early epithelial remodeling by engaging a miR-486a-5p/Skp2/GATA4 working model, offering a proof-of-concept therapeutic strategy for ALI.