S100A9 and chronic obstructive pulmonary disease: S100A8, S100A9, and S100A12 might induce neutrophil and monocyte chemotaxis, adhesion to fibrinogen and diapedesis, and neutrophil migration to inflammatory sites 46, 47, and have been identified as key biomarkers in inflammatory diseases including COPD and neutrophil‐dominated infections 35, 48, 49.