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Research Paper|Volume 12, Issue 12|pp 11325—11336

CD38 inhibition by apigenin ameliorates mitochondrial oxidative stress through restoration of the intracellular NAD+/NADH ratio and Sirt3 activity in renal tubular cells in diabetic rats

Yoshio Ogura1, Munehiro Kitada1,2, Jing Xu1,3, Itaru Monno1, Daisuke Koya1,2
  • 1Department of Diabetology and Endocrinology, Kanazawa Medical University, Ishikawa, Japan
  • 2Division of Anticipatory Molecular Food Science and Technology, Medical Research Institute, Kanazawa Medical University, Uchinada, Ishikawa, Japan
  • 3Department of Endocrinology and Metabolism, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, China
Received: March 14, 2020Accepted: May 1, 2020Published: June 7, 2020
https://doi.org/10.18632/aging.103410

Copyright © 2020 Ogura et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abstract

Mitochondrial oxidative stress is a significant contributor to the pathogenesis of diabetic kidney disease (DKD). We previously showed that mitochondrial oxidative stress in the kidneys of Zucker diabetic fatty rats is associated with a decreased intracellular NAD+/NADH ratio and NAD+-dependent deacetylase Sirt3 activity, and increased expression of the NAD+-degrading enzyme CD38. In this study, we used a CD38 inhibitor, apigenin, to investigate the role of CD38 in DKD. Apigenin significantly reduced renal injuries, including tubulointerstitial fibrosis, tubular cell damage, and pro-inflammatory gene expression in diabetic rats. In addition, apigenin down-regulated CD38 expression, and increased the intracellular NAD+/NADH ratio and Sirt3-mediated mitochondrial antioxidative enzyme activity in the kidneys of diabetic rats. In vitro, inhibition of CD38 activity by apigenin or CD38 knockdown increased the NAD+/NADH ratio and Sirt3 activity in renal proximal tubular HK-2 cells cultured under high-glucose conditions. Together, these results demonstrate that by inhibiting the Sirt3 activity and increasing mitochondrial oxidative stress in renal tubular cells, CD38 plays a crucial role in the pathogenesis of DKD.