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.