S100A12 and acute respiratory distress syndrome: The alveolar-to-arterial ratio of S100A12 was higher in ARDS patients than in controls at baseline (1 [0.3–1.8] vs. 0.2 [0.2–1], respectively, P = 0.03) and on D6 (1.1 [0.4–1.8] vs. 0.8 [0.02–1.6], P = 0.04), but it was lower in ARDS patients than in controls on D0H4 (1 [0.2–1.5] vs. 3.4 [0.8–8.2], P<0.0001), D3 (0.9 [0.7–2.1] vs. 1.5 [0.9–5.7], P = 0.01).