Metabolic Dysregulation of 27-Hydroxycholesterol Sensitizes Proximal Tubular Epithelial Cells to Ferroptosis in Ischemic Acute Kidney Injury

Cell death plays a pivotal role in ischemic acute kidney injury (AKI), with metabolic dysfunction emerging as a key contributor. However, the mechanism by which how metabolism imbalance initiates renal tubular cell death is poorly understood. We used combining single-cell spatial transcriptomics and metabolomics to characterize the function and metabolites of murine renal proximal cell subpopulations during ischemic AKI to CKD transition. Ferroptosis was identified as the predominant mode of cell death in severely injured proximal straight tubules following acute kidney injury (AKI). Further investigation revealed a critical deficiency in Cyp7b1, an enzyme responsible for metabolizing 27-hydroxycholesterol (27-HC) into 7α,27-dihydroxycholesterol, resulting in substantial 27-HC accumulation in proximal tubular cells during the early phase of ischemic AKI. Mechanistically, 27-HC acts as an endogenous ligand for estrogen receptor α (ERα), inducing downstream Hmox1 activation and thereby potentiating ferroptosis susceptibility in proximal tubular cells. Notably, adeno-associated virus (AAV)-mediated Cyp7b1 overexpression in a murine ischemia-reperfusion injury (IRI) model attenuated ferroptosis by enhancing 27-HC degradation, effectively mitigating ischemic AKI progression. These findings underscore the pivotal role of the Cyp7b1/27-HC axis in this pathological context. Our study delineated a unique mechanism of Cyp7b1/27-HC axis in proximal tubular cell ferroptosis in early AKI.