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Abstract: FR-OR30

Unbiased Human and Mouse Kidney Metabolomics Identifies the Key Role of NAD Metabolism in Kidney Disease Development

Session Information

Category: Glomerular Diseases

  • 1301 Glomerular Diseases: Fibrosis and Extracellular Matrix

Authors

  • Doke, Tomohito, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States
  • Susztak, Katalin, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, United States
Background

The kidney is a highly metabolically active organ and plays a key role in organismal metabolism. Changes in human kidney metabolism have been analyzed in an unbiased manner.

Methods

Here we collected 50 human kidney samples from healthy and chronic kidney disease subjects. We obtained clinical information, and histological analysis, and performed untargeted metabolomics (900 metabolites) and gene expression studies by RNA sequencing. Metabolites data was analyzed using Metaboanalyst. Gene expression analysis and untargeted metabolomic studies have also been performed for the cisplatin-induced mouse kidney injury model. Wild type and RIG-I knock-out mice were injected with cisplatin. We used the primary culture of mouse kidney tubule cells. Human snATAC and in situ hybridization were employed for validation.

Results

Untargeted metabolomics identified 153 metabolites showing differences in human CKD kidneys and 687 in mice. Pathway enrichment analysis indicated NAD metabolism pathway was commonly enriched in both human and mice metabolomics data. Treating mice with NAD precursor NR (Nicotinamide riboside) and NMN (Nicotinamide mononucleotide) ameliorated cisplatin-induced kidney disease severity. Unbiased gene expression analysis showed significant normalization of genes associated with cytosolic RNA sensing, and immune and mitochondrial pathways. In vitro cell culture studies indicated NAD precursor treatment protected from mitochondrial depolarization, ROS release, cell death, and proinflammatory gene expression. Molecular analysis showed that cisplatin treatment led to the cytosolic leakage of mitochondrial RNA and activation of the cytosolic RNA sensor RiG-I. Kidney damage, (BUN level, structural changes) was lower in cisplatin-treated RiG-I KO mice compared to wild-type animals. Increased Rig-I expression in renal tubules was confirmed in human disease kidneys. Kidney NAD levels negatively correlated with Rig-I, Isg15, and Irf7 expression in human kidneys.

Conclusion

Unbiased metabolomics of human kidneys highlighted changes in NAD metabolism. NAD precursor treatment protected from mitochondrial damage and improved kidney function in mice by preventing the activation of the cytosolic nucleotide sensors.

Funding

  • NIDDK Support