Lactobacillus rhamnosus GG-Derived Extracellular Vesicles Accumulated Lung Tissue to Attenuate Sepsis-Induced Acute Lung Injury by Suppressing Inflammation and Restoring Barrier Integrity.

BACKGROUND: Sepsis-induced acute lung injury (SALI) is a lethal disorder driven by cytokine storm, immune paralysis, and alveolar barrier collapse. Probiotic-derived extracellular vesicles (EVs), particularly nano-sized vesicles from Lactobacillus rhamnosus GG (LGG-EVs), represent promising nanotherapeutics against inflammatory lung injury. However, the specific effects and underlying mechanisms of LGG-EVs on SALI remain unclear. METHODS: After isolating and analyzing LGG-EVs, we used a CLP-induced sepsis model of mouse and an LPS-injured lung organoid model. We tracked the distribution and uptake of LGG-EVs using in vivo imaging and fluorescence microscopy. By using techniques including HE staining, ELISA, qPCR, WB, and IF, the effects of LGG-EVs on sepsis-induced lung injury were explored from the perspectives of pathology, inflammatory factor secretion, and key molecule expression. RESULTS: Utilizing a murine CLP model alongside LPS-stimulated lung organoids, which replicate the alveolar niche, we demonstrated that orally administered LGG-EVs preferentially accumulate in the lungs. These vesicles were found to mitigate tissue injury, suppress systemic inflammation, and restore barrier integrity. Through transcriptomic analyses and mechanistic investigations, it was demonstrated that LGG-EVs target hypoxia-inducible factor 1-alpha (HIF-1α), thereby restoring barrier function by reorganizing tight junctions. CONCLUSION: Collectively, we identify probiotic-derived EVs as promising pulmonary nanotherapeutics, with oral LGG-EVs emerging as a clinically viable SALI treatment strategy through HIF-1α targeting. This work provides comprehensive preclinical evidence to accelerate the translation of EV-based therapies for critical care applications.