Fig. 2

The pathological changes in ARDS. Acute respiratory distress syndrome affects not only pulmonary tissue but also extra-pulmonary tissues. Systemic pathological changes, such as immunoinflammation and immunothrombosis, occur throughout the body, and various cells are involved in these pathological changes including macrophage, monocyte, dendritic cell, neutrophil, eosinophil, T cell and endothelial cell. These changes are believed to contribute to cellular abnormalities within the pulmonary tissue, ultimately leading to damage to the alveolar-capillary barrier in ARDS. A variety of pulmonary pathological changes have been observed in the damaged lung tissue, including endothelial barrier dysfunction, the presence of cell-free hemoglobin, reduced resolution of pulmonary edema, cell death, cellular senescence, and cellular dysfunction. *M1: Proinflammatory phenotype of macrophages; NET: neutrophil extracellular trap; CFH: cell-free hemoglobin; AFC: alveolar fluid clearance