Background: Apoptosis is thought to play an important role in the development of acute respiratory distress syndrome (ARDS). We evaluated the bronchoalveolar lavage (BAL) fluid from ARDS patients focusing on apoptosis.
Methods: The study enrolled 31 ARDS patients and 20 healthy controls. BAL fluid levels of caspase-cleaved cytokeratin-18 (CK-18) and soluble mediators such as interleukin-8 (IL-8), soluble Fas (sFas), soluble Fas ligand (sFasL), growth-related oncogene-alpha (GRO-alpha), granulocyte colony-stimulating factor (G-CSF), and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) were measured using enzyme-linked immunosorbent assay (ELISA).
Results: The BAL fluid caspase-cleaved CK-18 levels in ARDS patients were higher than those in controls, reflecting increased epithelial apoptosis, and were correlated with lung injury scores (rs=0.49). The BAL fluid levels of all mediators were significantly higher in ARDS patients than in controls. In ARDS patients, the BAL fluid IL-8 level was positively correlated with the levels of sFas (rs=0.57), GRO-alpha (rs=0.47), and TRAIL (rs=0.45). The BAL fluid IL-8 (rs=0.61), sFas (rs=0.57), G-CSF (rs=0.44), and TRAIL (rs=0.33) levels were correlated with the BAL fluid neutrophil count. The G-CSF levels were significantly higher in non-surviving than in surviving ARDS patients [median 183.4 pg/mL (interquartile range 76.7-315.9) vs. 63.8 pg/mL (36.2-137.2); p<0.05]. The sFas levels were positively correlated with the PaO2/FiO2 ratio (rs=0.40), and the TRAIL levels were negatively correlated with the multiple organ dysfunction scores (rs=-0.37).
Conclusions: Among the mediators in BAL fluid from ARDS patients, G-CSF had the most significant prognostic implications, and the sFas and TRAIL levels were correlated with clinical severity.