EMAP-II from macrophage-derived extracellular vesicles drives neutrophil extracellular traps formation via...

Lung ischemia/reperfusion injury (LIRI) is a significant complication following lung transplantation driven by neutrophil extracellular traps (NETs) associated with mitochondrial oxidative stress. However, the intercellular signaling mechanisms mediating oxidative stress remain unresolved. Here, we elucidated a mitochondrial reactive oxygen species (mtROS) amplification mechanism driven by extracellular vesicles (EVs). In this mechanism, EVs derived from oxygen-glucose deprivation/reperfusion (OGD/R)-activated macrophages transferred endothelial monocyte-activating polypeptide-II (EMAP-II) to neutrophils, suppressed PI3K/AKT signaling, and thereby induced mitochondrial oxidative stress that drove pathological NETs formation. Proteomic profiling identified EMAP-II as a key signaling molecule enriched in EVs secreted by OGD/R-activated macrophages. Pharmacological inhibition of mtROS or AKT activation abolished NETs formation, confirming the PI3K/AKT/mtROS as the central redox-sensitive pathway. Crucially, shRNA-mediated EMAP-II knockdown in macrophages abolished the ability of OGD/R-EVs to induce mtROS and NETs formation, mitigating pulmonary inflammation and tissue injury in mice. This study establishes EMAP-II from macrophage-derived EVs as transcellular drivers of neutrophil mitochondrial oxidative stress. We propose EMAP-II blockade as a therapeutic strategy to disrupt the pathogenic cascade in LIRI, wherein macrophage-derived EVs trigger NETs formation through PI3K/AKT/mtROS.