Abstract
KEY POINTS: Integrated single-cell spatial transcriptomics and metabolomics identified cholesterol reprogramming as a driver of ferroptosis in proximal tubules. Targeting the Cyp7b1/27-hydroxycholesterol axis efficiently alleviated ferroptosis-induced proximal tubule injury during ischemic AKI. BACKGROUND: Cell death plays a pivotal role in ischemic AKI, with metabolic dysfunction emerging as a key contributor. However, the mechanism by which metabolism imbalance initiates renal tubular cell death is poorly understood. METHODS: We combined single-cell spatial transcriptomics and metabolomics to characterize the function and metabolites of murine renal proximal cell subpopulations during ischemic AKI to CKD transition. RESULTS: Ferroptosis was identified as the predominant mode of cell death in severely injured proximal straight tubules after AKI. Additional 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, inducing downstream Hmox1 activation and thereby potentiating ferroptosis susceptibility in proximal tubular cells. Notably, adeno-associated virus–mediated Cyp7b1 overexpression in a murine ischemia-reperfusion injury 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 pathologic context. CONCLUSIONS: Our study delineated a unique mechanism of Cyp7b1/27-HC axis in proximal tubular cell ferroptosis in early AKI.