Lung Tissue Extracellular Vesicles-Mediated Delivery of miR-128-3p as a Novel Mechanism of Acute Lung Inflammation.

BACKGROUND: Emerging evidence links macrophage overactivation to sepsis-associated acute lung injury (ALI), yet the role of lung tissue-derived extracellular vesicles (Ti-EVs) in this process remains unclear. This study combines transcriptomic profiling and functional validation to reveal how Lung Ti-EVs mediate macrophage polarization through miRNA-dependent NLRP3 inflammasome activation. METHODS: We established a sepsis mouse model, extracted and characterized lung tissue-derived EVs, performed high-throughput transcriptome sequencing and bioinformatics analysis. Intratracheal administration of these EVs to wild-type C57BL/6 mice revealed their effects on pulmonary inflammation, macrophage polarization, and proliferation. In vitro co-culture experiments with Raw264.7 macrophages further validated these findings and explored underlying mechanisms. RESULTS: We identified extracellular vesicles (EVs) enriched in lung tissues from septic ALI mice, selectively carrying miRNAs including miR-128-3p. In vivo administration of these EVs exacerbated pulmonary inflammation by expanding M1 macrophage populations, while in vitro experiments demonstrated EV-mediated miR-128-3p delivery to macrophages stimulated TNF-α and IL-6 production. Mechanistically, miR-128-3p promoted macrophage proliferation and inflammatory responses by targeting Rab20.