Santos, F. M.; Cuevas-Delgado, P.; Marchant, V.; Tejedor-Santamaria, L.; Rodrigues-Diez, R. R.; Ramos, A. M.; Sanz, A. B.; Ortiz, A.; Barbas, C.; Ruiz-Ortega, M.

Acute kidney injury (AKI) secondary to kidney ischemia reperfusion (IRI) is driven by profound metabolic perturbations that shape oxidative stress, inflammation, and cell death responses. Despite growing evidence of lipid dysregulation in AKI, its biological and mechanistic relevance remains unclear. To address this gap, we performed comprehensive untargeted kidney lipidomics using LC QTOF MS to delineate dynamic lipid changes during the acute phase of murine kidney IRI. Integration of lipidomic signatures with kidney gene-expression profiling and curated datamining revealed early activation of lipid pathways associated with injury responses. IRI induced marked lipidomic reprogramming, characterized by a marked accumulation of glycerolipids, including triacylglycerols (TGs) species detected exclusively after injury, together with increased levels of sphingolipids (ceramides, sphingomyelins, and hexosylceramides). Cardiolipins and most glycerophospholipids declined sharply following IRI, whereas specific phosphatidylcholines (PCs) exhibited opposite regulation, consistent with dynamic membrane remodeling. Datamining linked TG accumulation and altered transcriptional regulation of PC metabolism to repair-prone type 1 injured proximal tubular cells, highlighting its role in early tubular injury. Correlation analyses revealed strong associations between glycerolipids/sphingolipids and markers of renal dysfunction and inflammation, identifying TG 54:9 as a candidate for injury biomarker. Conversely, PE 40:6, PI 38:6, together with several lysophosphatidylcholines and ether-linked phospholipids, correlated positively with nephroprotective and antioxidant markers. Together, these patterns delineate two major lipid modules: a damage-associated module and a nephroprotection-associated module. These findings establish lipid remodeling as a central yet underexplored determinant of AKI pathogenesis and underscore lipidomics as a powerful discovery tool for identifying novel biomarkers and mechanistic targets in kidney disease.