S100A9 and acute kidney injury: Previous studies have reported that the elevated levels of urinary S100A8/A9 could help differentiate intrinsic‐AKI from pre‐renal AKI.[42, 43, 44] Together the data support the potential pathogenic roles of S100A8/S100A9+ macrophages in human AKI and S100A8/A9 may serve as a novel therapeutic target.