Prognostic Value of Angiopoietin-Like 4 in Patients with Acute Respiratory Distress Syndrome

BACKGROUND Angiopoietin-like 4 (ANGPTL4) is a secreted glycoprotein that plays an important role in endothelial injury and the inflammatory response. Experimental models have implicated ANGPTL4 in acute respiratory distress syndrome (ARDS), but its impact on the progression of ARDS is unclear. METHODS Paired bronchoalveolar lavage fluid (BALF) and serum samples were obtained from patients with ARDS (n = 56) within 24 h of diagnosis and from control subjects (n = 32). ANGPTL4, angiopoietin-2, interleukin (IL)-6 and tumor necrosis factor (TNF)-α levels were measured by magnetic Luminex assay. BALF albumin (BA) and serum albumin (SA) were evaluated by enzyme-linked immunosorbent assay. RESULTS BALF and serum ANGPTL4 concentrations were higher in patients with ARDS than in controls and were even higher in survivors than in non-survivors. The serum ANGPTL4 level was higher in indirect (extrapulmonary) ARDS than in direct (pulmonary) ARDS. Furthermore, BALF and serum ANGPTL4 levels correlated well with angiopoietin-2, IL-6, and TNF-α levels in BALF and serum. BALF ANGPTL4 was positively correlated with the BA/SA ratio (an indicator of pulmonary vascular permeability), and serum ANGPTL4 was associated with the severity of multiple organ dysfunction syndrome based on SOFA and APACHE II scores. Moreover, serum ANGPTL4 was better able to predict 28-day ARDS-related mortality (AUC 0.746, p < 0.01) than the APACHE II score or PaO2/FiO2 ratio. Serum ANGPTL4 was identified as an independent risk factor for mortality in a univariate Cox regression model (p < 0.001). CONCLUSION ANGPTL4 levels were elevated in patients with ARDS and significantly correlated with disease severity and mortality. ANGPTL4 may be a novel prognostic biomarker in ARDS.