title: Early lipid changes in acute kidney injury using SWATH lipidomics coupled with MALDI tissue imaging.
abstract: Acute kidney injury (AKI) is one of the leading causes of in-hospital morbidity and mortality, particularly in critically ill patients. Although our understanding of AKI at the molecular level remains limited due to its complex pathophysiology, recent advances in both quantitative and spatial mass spectrometric approaches offer new opportunities to assess the significance of renal metabolomic changes in AKI models. In this study, we evaluated lipid changes in early ischemia-reperfusion (IR)-related AKI in mice by using sequential window acquisition of all theoretical spectra (SWATH)-mass spectrometry (MS) lipidomics. We found a significant increase in two abundant ether-linked phospholipids following IR at 6 h postinjury, a plasmanyl choline, phosphatidylcholine (PC) O-38:1 (O-18:0, 20:1), and a plasmalogen, phosphatidylethanolamine (PE) O-42:3 (O-20:1, 22:2). Both of these lipids correlated with the severity of AKI as measured by plasma creatinine. In addition to many more renal lipid changes associated with more severe AKI, PC O-38:1 elevations were maintained at 24 h post-IR, while renal PE O-42:3 levels decreased, as were all ether PEs detected by SWATH-MS at this later time point. To further assess the significance of this early increase in PC O-38:1, we used matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS) to determine that it occurred in proximal tubules, a region of the kidney that is most prone to IR injury and also rich in the rate-limiting enzymes involved in ether-linked phospholipid biosynthesis. Use of SWATH-MS lipidomics in conjunction with MALDI-IMS for lipid localization will help in elucidating the role of lipids in the pathobiology of AKI.
authors.affiliation: Division of Pediatric Critical Care, Children's Hospital of Alabama, Birmingham, Alabama;
authors.forename: Sangeetha
authors.initials: S
authors.lastname: Rao
authors.affiliation: Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama; Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama;
authors.forename: Kelly B
authors.initials: KB
authors.lastname: Walters
authors.affiliation: Targeted Metabolomics and Proteomics Laboratory, Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama; and.
authors.forename: Landon
authors.initials: L
authors.lastname: Wilson
authors.affiliation: Division of Nephrology and Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Bo
authors.initials: B
authors.lastname: Chen
authors.affiliation: Division of Nephrology and Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Subhashini
authors.initials: S
authors.lastname: Bolisetty
authors.affiliation: Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama;
authors.forename: David
authors.initials: D
authors.lastname: Graves
authors.affiliation: Targeted Metabolomics and Proteomics Laboratory, Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama; and.
authors.forename: Stephen
authors.initials: S
authors.lastname: Barnes
authors.affiliation: Division of Nephrology and Nephrology Research and Training Center, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Anupam
authors.initials: A
authors.lastname: Agarwal
authors.affiliation: Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama; janusz@uab.edu.
authors.forename: Janusz H
authors.initials: JH
authors.lastname: Kabarowski
mesh_terms: D058186:Acute Kidney Injury / Q000209:etiology / Q000378:metabolism*; D000818:Animals; D050356:Lipid Metabolism; D008297:Male; D055432:Metabolomics / Q000379:methods*; D008810:Mice, Inbred C57BL; D015427:Reperfusion Injury / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
keywords: AKI; IR; MALDI-IMS; SWATH-MS; acute kidney injury; ischemia-reperfusion; lipidomics; matrix-assisted laser desorption ionization imaging mass spectrometry; sequential window acquisition of all theoretical spectra mass spectrometry