Interleukin-24 is a novel diagnostic biomarker for the severity of acute kidney injury

There is a clinical need for sensitive acute kidney injury (AKI) biomarkers that enable early therapeutic interventions and prediction of disease prognosis. In this study, we monitored interleukin (IL)-24 expressed in kidneys with severe AKI that progresses to atrophic kidney in a mouse model of ischemia–reperfusion injury (IRI). Therefore, we evaluated IL-24 as a potential biomarker not only for early diagnosis of AKI, but also for predicting progression to chronic kidney disease (CKD). Serum IL-24 was detected earlier than the elevation of serum creatinine levels and urinary IL-24 was detected as early as neutrophil gelatinase associated lipocalin (NGAL) in severe AKI (60 min of IRI). In addition, serum and urine IL-24 levels tended to increase in relation to ischemia duration. In such kidneys, vascular smooth muscle cells expressed IL-24 in response to the injury in the renal tubular epithelial cell and its target was the renal tubular epithelial cell itself. IL-24 may play a pivotal role in the communication between tubular epithelial cells and vascular smooth muscle cells and, in conclusion, IL-24 can be used as a sensitive biomarker for AKI.