To investigate the contribution of Trem2 macrophages to the AKI–CKD transition, WT and Trem2 knockout (Trem2KO) mice were subjected to renal UIRI (Figure 1A), which has been shown to be a reliable and robust animal model for studying the transition from AKI to CKD.45 The gene discussed is TREM2; the disease is chronic kidney disease.