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Kidney Week

Abstract: TH-PO1084

Calcineurin Inhibitors Cause Kidney Fibrosis by Inactivating Pyruvate Dehydrogenase and Disrupting Energy Metabolism in Proximal Tubule Cells

Session Information

  • CKD: Mechanisms - 1
    October 24, 2024 | Location: Exhibit Hall, Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

  • 2303 CKD (Non-Dialysis): Mechanisms

Authors

  • Oda, Yasuhiro, The University of Tokyo Graduate School of Medicine, Bunkyo, Tokyo, Japan
  • Nishi, Hiroshi, The University of Tokyo Graduate School of Medicine, Bunkyo, Tokyo, Japan
  • Yoshida, Teruhiko, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, United States
  • Kopp, Jeffrey B., National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland, United States
  • Nangaku, Masaomi, The University of Tokyo Graduate School of Medicine, Bunkyo, Tokyo, Japan
Background

Arteriolopathy is regarded as a hallmark of chronic calcineurin inhibitor (CNI) nephrotoxicity, but whether tubular cells play a causative role in the development of chronic CNI nephrotoxicity is not fully understood. Calcineurin was recently shown to directly dephosphorylate and activate pyruvate dehydrogenase (PDH), a gatekeeper of the TCA cycle. We hypothesized that 1) CNIs disrupt mitochondrial energy metabolism by decreasing the activity of PDH in energy-demanding proximal tubule cells (PTCs) in the kidneys and 2) the dysregulated mitochondrial metabolism causes cellular senescence, thereby contributing to kidney fibrosis.

Methods

Primary human renal proximal tubule epithelial cells (RPTECs) were cultured with cyclosporin A (CsA) or tacrolimus. Chronic CNI nephrotoxicity mouse model was created by feeding low-salt diet and administering 30 mg/kg/day CsA to ICR mice for up to 4 weeks.

Results

Single-nucleus RNA-seq showed that genes associated with oxidative phosphorylation were significantly downregulated in PTCs of chronic CNI mouse model compared to PTCs of its control mouse (FDR < 0.001, gene set enrichment analysis). CsA administration increased the ratio of KIM-1+ PTCs with an upregulated expression of genes associated with cellular senescence and TGF-β signaling. In primary human RPTECs cultured with CsA or tacrolimus, the amount of phosphorylated, inactivated PDH was increased, and PDH activity was decreased. Mitochondrial oxygen consumption was decreased in primary human RPTECs cultured with CsA or tacrolimus, and this decrease was ameliorated by lentiviral overexpression of PDP1, an endogenous phosphatase and activator of PDH. The level of senescence-associated β-galactosidase and senescence-associated gene expression was increased in primary human RPTECs cultured with CsA. Administering dichloroacetic acid, an activator of PDH, to chronic CNI nephrotoxicity mouse model alleviated the increase in both immunohistochemical staining of type I collagen in the kidneys and the upregulated expression of senescence-associated genes caused by CsA administration.

Conclusion

To our knowledge, this is the first study to show that CNIs disrupt energy metabolism by inactivating PDH in PTCs and that activating PDH ameliorates dysregulated energy metabolism as well as kidney fibrosis.

Funding

  • NIDDK Support