Region-Specific Metabolic Alterations in the Tryptophan Pathway in Cisplatin-Induced Acute Kidney Injury

Cisplatin (DDP) is widely utilized in the clinical treatment of malignant tumors, but its effectiveness is significantly compromised by the adverse effects of acute kidney injury (AKI). Renal tubular cells are primarily responsible for DDP-induced AKI (DDP-AKI); however, the responses of heterogeneous renal tubular cells to DDP exposure have not been thoroughly explored. In this study, we employed a targeted metabolomics approach to investigate the metabolic responses of renal tubular cells in DDP-AKI rats. Tubular cells were isolated from the renal cortex and outer medulla, and a chemical derivatization-based liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics method was applied. Our findings revealed distinct metabolic profiles in tubular cells from the renal cortex and outer medulla, with outer medullary cells exhibiting greater sensitivity to DDP exposure. Further analyses identified the tryptophan pathway as a critical factor contributing to these regional differences. Additional functional investigations showed that intermediate metabolites of the tryptophan pathway alleviated DDP cytotoxicity in both cortical and outer medullary tubular cells primarily through modulation of the Bcl2/Bax and Caspase-3 pathway. This study enhances our understanding of the metabolic characteristics of tubular cells across heterogeneous renal regions in DDP-AKI and facilitates further exploration of the underlying mechanisms of DDP-induced nephrotoxicity.