Abstract: SA-PO118
Glucose-Pyruvate Metabolism in Sepsis-Associated AKI
Session Information
- AKI: Metabolism and Cell Death
October 26, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Acute Kidney Injury
- 103 AKI: Mechanisms
Author
- Singh, Prabhleen, University of California San Diego, La Jolla, California, United States
Background
Metabolic reprograming from oxidative to glycolytic in proximal tubules (PT) in AKI has been proposed. However, in the cecal ligation and puncture (CLP) model of sepsis-AKI (sAKI), we found dynamic changes with reduced oxidative metabolism (OXPHOS), increased glycolytic enzymes, but decreased functional glycolysis in PTs. Pyruvate, from glucose via glycolysis, can convert to lactate or fuel OXPHOS and is regulated by pyruvate dehydrogenase (PDH) and inhibited by PDH kinase (PDK). We examined the PDH-PDK axis, which is key in the control of OXPHOS and glycolysis, in sAKI.
Methods
Kidneys from sham or CLP mice were harvested at 24 hours. Protein and mRNA expression of key components of glucose and pyruvate metabolism were examined. Seahorse Substrate Oxidation Stress kits were used to interrogate substrates that fuel OXPHOS real-time with specific inhibitors- etomoxir (ETO) for fatty acids (FA) and UK5099 for pyruvate in fresh isolated PTs. RNA sequencing and metabolomics were also performed.
Results
PDH E1, E2, E3 were reduced, phospho-PDH and PDK4 were increased in CLP. PDP, which activates PDH, and PDH enzyme activity were decreased in CLP. Glucose transporters (GLUT2, SGLT1), gluconeogenic enzymes (FBP and G6pc) were decreased, but pentose phosphate pathway enzymes (G6pdx and Pgd) were increased in CLP. PTs from shams showed no change with ETO or UK5099 but in CLP PTs ATP-linked and maximal respiration were lower with UK5099 showing reliance on pyruvate. RNA sequencing showed differential regulation of OXPHOS, TCA, and glucose metabolism in CLP kidneys with gene expression changes consistent with above for pyruvate and glucose metabolism. Targeted metabolomics showed pyruvic acid as among the top 25 metabolites altered in CLP kidneys.
Conclusion
Our results advance the findings of dynamic and complex metabolic changes in CLP kidneys. Inactivation of PDH by increased PDK4 diverts pyruvate away from OXPHOS, which can lead to less ATP and more tubular injury, given the reliance of OXPHOS on pyruvate in CLP PTs. Therapeutics targeted to tubular metabolism via PDH-PDK axis can impact sAKI.
Funding
- NIDDK Support