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Introduction: The progression of renal pathology in autosomal dominant polycystic kidney disease (ADPKD) involves a complex series of changes including renal cyst formation, interstitial cyst expansion, tubular atrophy, and fibrosis. Changes to in tissue metabolism and cyst fluid metabolite composition have been shown in ADPKD models, however it has been diffcult to discretely localize these compounds to specific regions of the kidney. Further, very little is known about lipid profiles within the kidney during ADPKD. We hypothesized that spatial lipidomic analysis during periods of cyst expansion would reveal new understanding of changes in lipid metabolism during this critical window of pathology. In this study we focused on changes in the mcwPkd1 nl/nl mouse, a hypomorphic ADPKD model that rapidly develops a cystic phenotype. Methods: Kidneys were collected from female cystic mcwPkd1 nl/nl mice at postnatal days 7, 14 and 28, representing periods preceding, during and at maximal cyst expansion, respectively. Control kidneys were collected from female wild-type littermates at postnatal day 7 and 28. Tissues were rapidly cryoembedded for 10 mm sectioning onto Intellislides (BrukerDaltonik). Slides were scanned on a Reflecta MF-5000 scanner and sprayed with 7 mg/mL CHCA in 70% Acetonitrile, 30% water and 0.1% TFA using a TM Sprayer Model M3 (HTX Technologies, LLC). Mass spec imaging data was acquired with a Bruker timsTOF Flex system (BrukerDaltonik) with a Smartbeam 3D laser at 10kHz and 10 μm resolution. Imaging data analysis was performed in SCiLS Lab software (version 2023b, Bruker). Calculations were performed on data normalized to total ion count (TIC). Spatial segmentation analysis of data was performed using an unsupervised bisecting k-means algorithm and resulting clusters were investigated by ROC. Lipid annotation was performed the Lipid Species annotation tool with MSDial VS68 spectral library in Metaboscape (version 2022b, Bruker). Results: There were vast global differences between lipid composition of wild-type and cystic kidneys at postnatal day 28. When comparing cystic to wild-type kidneys phosphoinositol and ceremide lipid species were decreased and other metabolites, such as thiophene-3-carboxylate and benzothiazine-2-carbonitrile, were increased at both PN7 and PN28. Further numerous lipid compounds were identified only within cystic fluid that have not been previously annotated. Conclusions: The results of this study, for the first time, reveals alterations in lipid molecule profiles throughout the cystic kidney in tandem with morphological changes. This is a major step forward in understanding how lipid metabolism changes in response to cyst expansion during the progression of ADPKD, as well as revealing molecular changes that precede cellular pathology. This work has been supported by Children’s Wisconsin Foundation and Children’s Research Institute. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Kriegel et al. (Wed,) studied this question.