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©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
Empagliflozin alleviates podocytopathy and enhances glomerular nephrin expression in db/db diabetic mice
Vadim V Klimontov, Anton I Korbut, Iuliia S Taskaeva, Nataliya P Bgatova, Maksim V Dashkin, Nikolai B Orlov, Anna S Khotskina, Evgenii L Zavyalov, Thomas Klein
Vadim V Klimontov, Anton I Korbut, Maksim V Dashkin, Laboratory of Endocrinology, Research Institute of Clinical and Experimental Lymphology – Branch of the Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (RICEL–Branch of IC&G SB RAS), Novosibirsk 630060, Russia
Iuliia S Taskaeva, Nataliya P Bgatova, Laboratory of Ultrastructural Research, Research Institute of Clinical and Experimental Lymphology – Branch of the Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (RICEL–Branch of IC&G SB RAS), Novosibirsk 630060, Russia
Nikolai B Orlov, Laboratory of Clinical Immunogenetics, Research Institute of Clinical and Experimental Lymphology – Branch of the Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (RICEL–Branch of IC&G SB RAS), Novosibirsk 630060, Russia
Anna S Khotskina, Evgenii L Zavyalov, Center for Genetic Resources of Laboratory Animals, Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
Thomas Klein, Department of Cardiometabolic Diseases Research, Boehringer Ingelheim Pharma GmbH, Biberach 88397, Germany
Author contributions: Klimontov VV designed and coordinated the study; Korbut AI, Taskaeva IS, Dashkin MV, Orlov NB and Khotskina AS performed the experiments, acquired and analyzed data; Klimontov VV, Bgatova NP, Zavjalov EL and Klein T interpreted the data; Klimontov VV and Korbut AI wrote the manuscript; all authors approved the final version of the article.
Supported by Ministry of Science and Higher Education of Russia (the budget projects No. 0324-2019-0045/0324-2019-0045-C-02; grant No. RFMEFI62119X0023) and Boehringer Ingelheim Pharma.
Institutional review board statement: The protocol was approved by the Ethics Committee of the Institute of Clinical and Experimental Lymphology (Protocol 1/2; 1 April 2014) and by the Inter-Institutional Animal Ethics Committee based on the Institute of Cytology and Genetics SB RAS (Protocol 21; 1 April 2014).
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of the Center of Genetic Resources of Laboratory Animals based on the SPF Vivarium of Institute of Cytology and Genetics SB RAS (Protocol 24; 8 April 2014).
Conflict-of-interest statement: VVK received honorariafrom Boehringer Ingelheim for the lectures and advising boards. TK is an employee of Boehringer Ingelheim Pharma. Other authors declare they have no competing interest.
Data sharing statement: The datasets used and analyzed during the current study are available from the corresponding author on the request.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
http://creativecommons.org/Licenses/by-nc/4.0/ Corresponding author: Vadim V Klimontov, DSc, MD, PhD, Professor, Laboratory of Endocrinology, Research Institute of Clinical and Experimental Lymphology – Branch of the Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences (RICEL–Branch of IC&G SB RAS), 2 Timakov Street, Novosibirsk 630060, Russia. klimontov@mail.ru
Received: July 14, 2020
Peer-review started: July 14, 2020
First decision: September 21, 2020
Revised: September 28, 2020
Accepted: October 13, 2020
Article in press: November 9, 2020
Published online: December 15, 2020
ARTICLE HIGHLIGHTS
Research background
Sodium-glucose cotransporter-2 (SGLT2) inhibitors have opened up new prospects for the prevention of chronic kidney disease (CKD). Modern guidelines recommend SGLT2 inhibitors as the preferred antihyperglycemic agents for patients with type 2 diabetes (T2D) and CKD. In the empagliflozin (EMPA)-REG OUTCOME trial, the SGLT2 inhibitor EMPA prevented increased albuminuria and progression of renal function decline in T2D patients.
Research motivation
The exact mechanisms of the renal effect of SGLT2 inhibitors are not fully understood. Since diabetic kidney disease is accompanied by podocyte injury and this injury results in albuminuria, it can be speculated that the anti-albuminuric action of SGLT2 inhibitors could be mediated via podocytes. The influence of SGLT2 inhibitors on podocyte structure and function remains to be clarified.
Research objectives
In this study, we estimated the effect of EMPA on glomerular structural changes, with a special focus on podocytes, and glomerular nephrin staining, in db/db mice, a model of T2D. Thereby, we assessed the hypothesis that the anti-albuminuric effect of EMPA is linked with the preservation of podocyte integrity in diabetic kidney disease.
Research methods
We treated 8-wk-old db/db male mice with EMPA (10 mg/kg/d) or vehicle for 8 wk. Heterozygous db/+ mice were included as non-diabetic controls. Body weight and body composition were assessed every 4 wk. The plasma levels of glucose, glycated proteins, lipids, creatinine, leptin, insulin, glucagon, and albuminuria were monitored. Renal structure was studied by light and transmission electron microscopy. Glomerular nephrin and transforming growth factor beta (TGF-β) were assessed by immunohistochemistry. The fractional mesangial and capillary volume, glomerular basement membrane and podocyte foot processes width, numerical density of podocyte foot processes, as well as volumetric density of nephrin-positive and TGF-β-positive areas in glomeruli were quantified.
Research results
Throughout the experiment, diabetic mice showed a dramatic elevation in the body weight and fat mass. The observed increase in serum levels of glucose, glycated proteins, cholesterol, triglycerides, leptin and insulin characterized the metabolic profile of T2D. In db/db mice, EMPA mitigated renal hypertrophy, decreased mesangial fractional volume, the width of glomerular basement membrane, and glomerular TGF-β staining. EMPA-treated db/db mice demonstrated fewer signs of podocyte foot process effacement and restored glomerular staining of nephrin. These effects were correlated with a reduction of albuminuria. The improvement in podocyte integrity was observed even though normoglycemia was not achieved.
Research conclusions
This is the first study to quantitatively describe the effects of EMPA on podocyte structure and glomerular staining of nephrin in a model of T2D. The data indicate that EMPA attenuates podocytopathy in experimental diabetic kidney disease. The anti-albuminuric effect of EMPA could be attributed to mitigation of podocyte injury and enhancement of nephrin expression. The protective effect of EMPA on the kidneys is realized even in condition of suboptimal glycemic control.
Research perspectives
Uncovering the molecular pathways which are important for the effect of SGLT2 inhibitors on podocyte homeostasis is a challenge for further research.
