Basic Study
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 21, 2020; 26(23): 3225-3235
Published online Jun 21, 2020. doi: 10.3748/wjg.v26.i23.3225
Sodium glucose co-transporter 2 inhibition reduces succinate levels in diabetic mice
Lakshini Y Herat, Natalie C Ward, Aaron L Magno, Elizabeth P Rakoczy, Marcio G Kiuchi, Markus P Schlaich, Vance B Matthews
Lakshini Y Herat, Vance B Matthews, School of Biomedical Sciences, Dobney Hypertension Centre, Royal Perth Hospital Unit, University of Western Australia, Perth 6000, Australia
Natalie C Ward, Faculty of Health and Medical Sciences, University of Western Australia, Crawley 6009, Australia
Natalie C Ward, Faculty of Health Sciences, School of Public Health, Curtin University, Bentley 6102, Australia
Aaron L Magno, Research Centre, Royal Perth Hospital, Perth 6000, Australia
Elizabeth P Rakoczy, Department of Molecular Ophthalmology, University of Western Australia, Crawley 6009, Australia
Marcio G Kiuchi, Markus P Schlaich, Dobney Hypertension Centre, School of Medicine, Royal Perth Hospital Unit, University of Western Australia, Perth 6000, Australia
Markus P Schlaich, Department of Cardiology and Department of Nephrology, Royal Perth Hospital, Perth 6000, Australia
Author contributions: Matthews VB and Schlaich MP are equal senior authors and funded the study; Matthews VB designed and coordinated the study; Herat LY, Ward NC and Matthews VB performed the experiments, acquired and analysed data and wrote the manuscript; Magno AL performed the experiments; all authors provided intellectual input; all authors proof read the manuscript and approved the final version of the article.
Supported by the Royal Perth Hospital Medical Research Foundation, No. VMMRF2018.
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 Harry Perkins Institute for Medical Research (AE141/2019).
Conflict-of-interest statement: Prof. Schlaich is supported by a National Health and Medical Research Council Research Fellowship and has received research support from Medtronic, Abbott, Novartis, Servier, Pfizer, and Boehringer Ingelheim. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose. No potential conflicts of interest exist from other authors.
Data sharing statement: No additional data are available.
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: Vance B Matthews, BSc, PhD, Senior Research Fellow, School of Biomedical Sciences, Dobney Hypertension Centre, Royal Perth Hospital Unit, University of Western Australia, Level 3, MRF Building, Rear 50 Murray Street, Perth 6000, Australia. vance.matthews@uwa.edu.au
Received: February 28, 2020
Peer-review started: February 28, 2020
First decision: April 22, 2020
Revised: May 19, 2020
Accepted: June 9, 2020
Article in press: June 9, 2020
Published online: June 21, 2020
Abstract
BACKGROUND

Type 1 diabetes (T1D) is associated with major chronic microvascular complications which contribute significantly to diabetes associated morbidity. The protein primarily responsible for glucose reabsorption in the kidney is sodium glucose co-transporter 2 (SGLT2). Presently, SGLT2 inhibitors are widely used in diabetic patients to improve blood glucose levels and prevent cardiovascular and renal complications. Given the broad therapeutic application of SGLT2 inhibitors, we hypothesised that SGLT2 inhibition may exert its protective effects via alterations of the gut microbiome and tested this in a type 1 diabetic mouse model of diabetic retinopathy.

AIM

To determine whether the treatment with two independent SGLT2 inhibitors affects gut health in a type 1 diabetic mouse model.

METHODS

The SGLT2 inhibitors empagliflozin or dapagliflozin (25 mg/kg/d) or vehicle dimethylsulfoxide (DMSO) were administered to C57BL/6J, Akita, Kimba and Akimba mice at 10 wk of age for 8 wk via their drinking water. Serum samples were collected and the concentration of succinate and the short chain fatty acid (SCFA) butyric acid was measured using gas chromatography-mass spectrometry. Enzyme-linked immunosorbent assay (ELISA) was performed to determine the concentration of insulin and leptin. Furthermore, the norepinephrine content in kidney tissue was determined using ELISA. Pancreatic tissue was collected and stained with haematoxylin and eosin and analysed using brightfield microscopy.

RESULTS

Due to the presence of the Akita allele, both Akita and Akimba mice showed a reduction in insulin production compared to C57BL/6J and Kimba mice. Furthermore, Akita mice also showed the presence of apoptotic bodies within the pancreatic islets. The acinar cells of Akita and Akimba mice showed swelling which is indicative of acute injury or pancreatitis. After 8 wk of SGLT2 inhibition with dapagliflozin, the intermediate metabolite of gut metabolism known as succinate was significantly reduced in Akimba mice when compared to DMSO treated mice. In addition, empagliflozin resulted in suppression of succinate levels in Akimba mice. The beneficial SCFA known as butyric acid was significantly increased in Akita mice after treatment with dapagliflozin when compared to vehicle treated mice. The norepinephrine content in the kidney was significantly reduced with both dapagliflozin and empagliflozin therapy in Akita mice and was significantly reduced in Akimba mice treated with empagliflozin. In non-diabetic C57BL/6J and Kimba mice, serum leptin levels were significantly reduced after dapagliflozin therapy.

CONCLUSION

The inhibition of SGLT2 reduces the intermediate metabolite succinate, increases SCFA butyric acid levels and reduces norepinephrine content in mouse models of T1D. Collectively, these improvements may represent an important mechanism underlying the potential benefits of SGLT2 inhibition in T1D and its complications.

Keywords: Sodium glucose co-transporter inhibitors, Sodium glucose co-transporter 2, Diabetes, Diabetic retinopathy, Mouse, Gut microbiota, Empagliflozin, Dapagliflozin, Succinate, Akimba

Core tip: This novel study has shown in a murine model of type 1 diabetes (T1D), that Sodium glucose co-transporter 2 (SGLT2) inhibition reduces serum succinate levels, increases short-chain fatty acid butyric acid levels and reduces norepinephrine content. These beneficial effects on T1D and its complications may highlight important mechanisms underlying the potential benefits of SGLT2 inhibition.