Lung contusion drives lung injury by modifying miRNA cargo in alveolar small extracellular vesicles.

OBJECTIVE: To evaluate the micro-RNA (miRNA) cargo of alveolar small extracellular vesicles (sEVs) after lung contusion (LC), which can contribute to the development of trauma-related acute lung injury (ALI). METHODS: A mouse model of LC was conducted with a controlled cortical impact device. Bronchoalveolar lavage fluid (BAL) was collected 24 h post-injury and sEVs were purified using size exclusion chromatography. sEVs characteristics and miRNA cargo were analyzed with vesicle flow cytometry and sequencing. Macrophages were treated with BAL sEVs in vitro to assess their pro-inflammatory effect. RESULTS: LC increased lung permeability and caused ALI histologically. LC increased the number of sEVs in the BAL and altered their miRNA cargo. BAL sEVs collected after LC increased pro-inflammatory cytokine release from macrophages. CONCLUSION: LC increased the mobilization of sEVs to the alveolar space and modified their miRNA cargo that might contribute to the development of ALI by activating the immune response in macrophages.