CD14 positive extracellular vesicles in broncho-alveolar lavage fluid as a new biomarker of acute respiratory distress syndrome

Recent studies have indicated that extracellular vesicles (EV) may play a role in the pathogenesis of Acute Respiratory Distress Syndrome (ARDS). EV have been identified as potential biomarkers of disease severity and prognosis in other pulmonary diseases. We sought to characterize the EV phenotype within ARDS patient broncho-alveolar lavage fluid (BAL), and to determine whether BAL EV could be utilized as a potential biomarker in ARDS. EV from the BAL of sepsis patients with ARDS, sepsis patients without ARDS, and post-operative control patients were characterized with regards to size, number and cell of origin. ARDS patients had significantly higher numbers of CD14⁺/CD81⁺ monocyte-derived BAL EV than sepsis patients without ARDS (p=0.022). CD14⁺/CD81⁺ BAL EV numbers were significantly higher in those ARDS patients who died during the 30 days following ICU admission (p=0.027). Also, across all sepsis patients there was an association between CD66b⁺/CD63⁺ neutrophil-derived BAL EV and increased BAL IL-8 concentration, increased alveolar neutrophil apoptosis and decreased alveolar macrophage efferocytosis. Thus, CD14⁺/CD81⁺ BAL EV are a potential biomarker for disease severity and mortality in ARDS. These findings provide the impetus to further elucidate the contribution of these EV to ARDS pathogenesis.