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Göpel SO, Adingupu D, Wang J, Semenova E, Behrendt M, Jansson-Löfmark R, Ahlström C, Jönsson-Rylander AC, Gopaul VS, Esterline R, Gan LM, Xiao RP. SGLT2 inhibition improves coronary flow velocity reserve and contractility: role of glucagon signaling. Cardiovasc Diabetol 2024; 23:408. [PMID: 39548491 PMCID: PMC11568596 DOI: 10.1186/s12933-024-02491-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2024] [Accepted: 10/24/2024] [Indexed: 11/18/2024] Open
Abstract
BACKGROUND SGLT2 inhibitors, a T2DM medication to lower blood glucose, markedly improve cardiovascular outcomes but the underlying mechanism(s) are not fully understood. SGLT2i's produce a unique metabolic pattern by lowering blood glucose without increasing insulin while increasing ketone body and glucagon levels and reducing body weight. We tested if glucagon signaling contributes to SGLT2i induced improvement in CV function. METHODS Cardiac contractility and coronary flow velocity reserve (CFVR) were monitored in ob/ob mice and rhesus monkeys with metabolic syndrome using echocardiography. Metabolic status was characterized by measuring blood ketone levels, glucose tolerance during glucose challenge and Arg and ADMA levels were measured. Baysian models were developed to analyse the data. RESULTS Dapagliflozin improved CFVR and contractility, co-application of a glucagon receptor inhibitor (GcgRi) blunted the effect on CFVR but not contractility. Dapagliflozin increased the Arg/ADMA ratio and ketone levels and co-treatment with GcgRi blunted only the Dapagliflozin induced increase in Arg/ADMA ratio but not ketone levels. CONCLUSIONS Since GcgRi co-treatment only reduced the Arg/ADMA increase we hypothesize that dapagliflozin via a glucagon-signaling dependent pathway improves vascular function through the NO-signaling pathway leading to improved vascular function. Increase in ketone levels might be a contributing factor in SGLT2i induced contractility increase and does not require glucagon signaling.
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Affiliation(s)
- Sven O Göpel
- Global Patient Safety BioPharmaceuticals, AstraZeneca, Gothenburg, Sweden.
| | - Damilola Adingupu
- Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Jue Wang
- College of Future Technology, Peking University, Beijing, 100871, China
| | - Elizaveta Semenova
- Data Sciences and Quantitative Biology, Discovery Sciences, R&D, AstraZeneca, Cambridge, UK
- Imperial College London, School of Public Health, Department of Epidemiology and Biostatistics, London, United Kingdom
| | - Margareta Behrendt
- Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Rasmus Jansson-Löfmark
- Drug Metabolism and Pharmacokinetics, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Christine Ahlström
- Drug Metabolism and Pharmacokinetics, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Ann-Cathrine Jönsson-Rylander
- Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - V Sashi Gopaul
- Drug Metabolism and Pharmacokinetics, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | | | - Li-Ming Gan
- Ribocure Pharmaceuticals AB, Gothenburg, Sweden & SuZhou Ribo Life Science Co. Ltd., Gothenburg, Sweden
- Department of Cardiology, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Rui-Ping Xiao
- College of Future Technology, Peking University, Beijing, 100871, China
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Sohn M, Nam S, Nauck MA, Lim S. Long-term comparison of renal and metabolic outcomes after sodium-glucose co-transporter 2 inhibitor or glucagon-like peptide-1 receptor agonist therapy in type 2 diabetes. BMC Med 2024; 22:273. [PMID: 38956548 PMCID: PMC11218058 DOI: 10.1186/s12916-024-03483-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 06/13/2024] [Indexed: 07/04/2024] Open
Abstract
BACKGROUND Renal outcomes in patients with type 2 diabetes following treatment with sodium-glucose co-transporter-2 inhibitors (SGLT2is) or glucagon-like peptide-1 receptor agonists (GLP1RAs) have not been directly compared. This study compared the impact of SGLT2i and GLP1RA therapy on renal function and metabolic parameters. METHODS Patients with type 2 diabetes who initiated SGLT2i or GLP1RA therapy in a tertiary hospital between January 2009 and August 2023 were included to assess composite renal outcomes, such as a 40% decline in estimated glomerular filtration rate (eGFR), onset of end-stage renal disease, renal death, or new-onset macroalbuminuria. Alterations in blood pressure, glucose regulation parameters, lipid profile, and anthropometric parameters, including body fat and muscle masses, were examined over 4-years. RESULTS A total of 2,112 patients were enrolled using a one-to-three propensity-score matching approach (528 patients for GLP1RAs, 1,584 patients for SGLT2i). SGLT2i treatment was favoured over GLP1RA treatment, though not significantly, for composite renal outcomes (hazard ratio [HR], 0.63; p = 0.097). SGLT2i therapy preserved renal function effectively than GLP1RAs (decrease in eGFR, ≥ 40%; HR, 0.46; p = 0.023), with improving albuminuria regression (HR, 1.72; p = 0.036). SGLT2i therapy decreased blood pressure and body weight to a greater extent. However, more patients attained HbA1c levels < 7.0% with GLP1RAs than with SGLT2is (40.6% vs 31.4%; p < 0.001). GLP1RA therapy enhanced β-cell function and decreased LDL-cholesterol levels below baseline values. CONCLUSIONS SGLT2is were superior for preserving renal function and reducing body weight, whereas GLP1RAs were better for managing glucose dysregulation and dyslipidaemia.
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Affiliation(s)
- Minji Sohn
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82, Gumi-ro 173 Beon-gil, Bundang-gu, Seongnam-City, 13620, South Korea
| | - Seoungyeon Nam
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82, Gumi-ro 173 Beon-gil, Bundang-gu, Seongnam-City, 13620, South Korea
| | - Michael A Nauck
- Section Diabetes, Endocrinology, Metabolism, Medical Department I Katholisches Klinikum Bochum gGmbH, St. Josef Hospital Ruhr-University Bochum, Bochum, Germany
| | - Soo Lim
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 82, Gumi-ro 173 Beon-gil, Bundang-gu, Seongnam-City, 13620, South Korea.
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Jojima T, Sakurai S, Kishi H, Kato K, Iijima T, Tomaru T, Usui I, Aso Y. Empagliflozin increases plasma levels of citrulline, histidine, and α-aminobutyric acid in patients with type 2 diabetes: effects of a sodium-glucose co-transporter 2 inhibitor on the plasma amino acid profile. Expert Opin Pharmacother 2024; 25:937-944. [PMID: 38809611 DOI: 10.1080/14656566.2024.2362265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 05/28/2024] [Indexed: 05/31/2024]
Abstract
BACKGROUND To investigate effects of empagliflozin on plasma amino acids in people with type 2 diabetes. RESEARCH DESIGN AND METHODS In a randomized, active-controlled, open-label trial, 58 patients with type 2 diabetes were randomized to 10 mg/day empagliflozin (n = 29) or standard treatment without empagliflozin (control group, n = 29) and treated for 12 weeks. We obtained blood samples at baseline and 12 weeks and assessed the plasma amino acid profile by liquid chromatography-mass spectrometry liquid chromatography. We also calculated the Fischer ratio (the ratio of branched-chain to aromatic amino acids). RESULTS In the empagliflozin group but not in the control group, plasma levels of citrulline, histidine, and α-aminobutyric acid (AABA), the Fischer ratio, and serum high-molecular weight (HMW) adiponectin increased significantly (p = 0.0099, 0.0277, 0.0318, 0.0135, and 0.0304, respectively) and plasma plasminogen activator inhibitor-1 (PAI-1) decreased significantly (p = 0.0014). In the empagliflozin group, the change in plasma citrulline was positively correlated with the changes in HMW adiponectin (r = 0.488, p = 0.0084) and the Fischer ratio (r = 0.393, p = 0.0353) but negatively correlated with the change in ferritin (r= -0.533,p = 0.0051); the change in plasma histidine was negatively correlated with the change in PAI-1 (r= -0.398, p = 0.0397) and urinary albumin creatinine ratio (r= -0.478, p = 0.0088). CONCLUSION Empagliflozin significantly increases plasma citrulline, histidine, and AABA in people with type 2 diabetes. CLINICAL TRIAL REGISTRATION www.umin.ac.jp identifier is UMIN000025418.
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Affiliation(s)
- Teruo Jojima
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Japan
| | - Shintaro Sakurai
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Japan
| | - Haruka Kishi
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Japan
| | - Kananko Kato
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Japan
| | - Toshie Iijima
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Japan
| | - Takuya Tomaru
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Japan
| | - Isao Usui
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Japan
| | - Yoshimasa Aso
- Department of Endocrinology and Metabolism, Dokkyo Medical University, Mibu, Japan
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Speedtsberg ES, Tepel M. Narrative review investigating the nephroprotective mechanisms of sodium glucose cotransporter type 2 inhibitors in diabetic and nondiabetic patients with chronic kidney disease. Front Endocrinol (Lausanne) 2023; 14:1281107. [PMID: 38174341 PMCID: PMC10761498 DOI: 10.3389/fendo.2023.1281107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/16/2023] [Indexed: 01/05/2024] Open
Abstract
Background and aims Outcome trials using sodium glucose cotransporter type 2 inhibitors have consistently shown their potential to preserve kidney function in diabetic and nondiabetic patients. Several mechanisms have been introduced which may explain the nephroprotective effect of sodium glucose cotransporter type 2 inhibitors beyond lowering blood glucose. This current narrative review has the objective to describe main underlying mechanisms causing a nephroprotective effect and to show similarities as well as differences between proposed mechanisms which can be observed in patients with diabetic and nondiabetic chronic kidney disease. Methods We performed a narrative review of the literature on Pubmed and Embase. The research string comprised various combinations of items including "chronic kidney disease", "sodium glucose cotransporter 2 inhibitor" and "mechanisms". We searched for original research and review articles published until march, 2022. The databases were searched independently and the agreements by two authors were jointly obtained. Results Sodium glucose cotransporter type 2 inhibitors show systemic, hemodynamic, and metabolic effects. Systemic effects include reduction of blood pressure without compensatory activation of the sympathetic nervous system. Hemodynamic effects include restoration of tubuloglomerular feedback which may improve pathologic hyperfiltration observed in most cases with chronic kidney disease. Current literature indicates that SGLT2i may not improve cortical oxygenation and may reduce medullar oxygenation. Conclusion Sodium glucose cotransporter type 2 inhibitors cause nephroprotective effects by several mechanisms. However, several mediators which are involved in the underlying pathophysiology may be different between diabetic and nondiabetic patients.
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Affiliation(s)
- Emma S Speedtsberg
- Institute of Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
- Institute of Clinical Medicine, University of Southern Denmark, Odense, Denmark
- Department of Nephrology, Odense University Hospital, Odense, Denmark
| | - Martin Tepel
- Institute of Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
- Institute of Clinical Medicine, University of Southern Denmark, Odense, Denmark
- Department of Nephrology, Odense University Hospital, Odense, Denmark
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Banerjee M, Pal R, Maisnam I, Chowdhury S, Mukhopadhyay S. Serum uric acid lowering and effects of sodium-glucose cotransporter-2 inhibitors on gout: A meta-analysis and meta-regression of randomized controlled trials. Diabetes Obes Metab 2023; 25:2697-2703. [PMID: 37334516 DOI: 10.1111/dom.15157] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 05/19/2023] [Accepted: 05/20/2023] [Indexed: 06/20/2023]
Abstract
AIMS To pool the effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors on gout and to investigate the association of these effects with baseline serum uric acid (SUA), SUA lowering, and underlying conditions, such as type 2 diabetes mellitus (T2DM)/heart failure (HF). METHODS PubMed, Embase, Web of Science, Cochrane Library and clinical trial registry websites were searched for randomized controlled trials (RCTs) or post hoc analyses (≥1-year duration; PROSPERO:CRD42023418525). The primary outcome was a composite of gouty arthritis/gout flares and commencement of anti-gout drugs (SUA-lowering drugs/colchicine). Hazard ratios (HRs) with 95% confidence interval (CI) were pooled using a generic inverse-variance method with a random-effects model. Mixed-effects model univariate meta-regression analysis was performed. RESULTS Five RCTs involving 29 776 patients (T2DM, n = 23 780) and 1052 gout-related events were identified. Compared to placebo, SGLT2 inhibitor use was significantly associated with reduced risk of composite gout outcomes (HR 0.55, 95% CI 0.45-0.67; I2 = 61%, P < 0.001). Treatment benefits did not differ between trials being conducted exclusively in baseline HF versus those conducted in patients with T2DM (P-interaction = 0.37), but were greater with dapagliflozin 10 mg and canagliflozin 100/300 mg (P < 0.01 for subgroup differences). Sensitivity analysis excluding trials that evaluated the effects of empagliflozin 10/25 mg (HR 0.68, 95% CI 0.57-0.81; I2 = 0%) accentuated the benefits of SGLT2 inhibitors with no between-trial heterogeneity (HR 0.46, 95% CI 0.39-0.55; I2 = 0%). Univariate meta-regression found no impact of baseline SUA, SUA lowering on follow-up, diuretic use, or other variables on their anti-gout effects. CONCLUSION We found that SGLT2 inhibitors significantly reduced the risk of gout in individuals with T2DM/HF. Lack of an association with SUA-lowering effects suggests that metabolic and anti-inflammatory effects of SGLT2 inhibitors may predominantly mediate their anti-gout benefits.
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Affiliation(s)
- Mainak Banerjee
- Department of Endocrinology, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Rimesh Pal
- Department of Endocrinology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Indira Maisnam
- Department of Endocrinology, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Subhankar Chowdhury
- Department of Endocrinology, Institute of Post Graduate Medical Education and Research, Kolkata, India
| | - Satinath Mukhopadhyay
- Department of Endocrinology, Institute of Post Graduate Medical Education and Research, Kolkata, India
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Ekanayake P, Mudaliar S. Increase in hematocrit with SGLT-2 inhibitors - Hemoconcentration from diuresis or increased erythropoiesis after amelioration of hypoxia? Diabetes Metab Syndr 2023; 17:102702. [PMID: 36657305 DOI: 10.1016/j.dsx.2022.102702] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 12/27/2022] [Accepted: 12/29/2022] [Indexed: 01/01/2023]
Abstract
BACKGROUND AND AIMS The SGLT2-inhibitors significantly reduce heart failure hospitalization and progression to end-stage kidney disease. An increase in hemoglobin/hematocrit is seen with SGLT2i-inhibitor treatment. This increase has been attributed to hemoconcentration resulting from a diuretic effect. In this review, we present evidence suggesting that the hematocrit increase is not due to hemoconcentration, but to an increase in erythropoiesis due to amelioration of hypoxia and more efficient erythropoietin production with SGLT2-inhibitor treatment. METHODS We performed a detailed review of the literature in PubMed for articles describing various mechanisms linking hematocrit increase with SGLT2-inhibitor use to their cardio-renal benefits. RESULTS The best predictor of cardio-renal benefits with SGLT2-inhibitors is an increase in hematocrit and hemoglobin. If this hemoconcentration is a results of diuresis, this would be associated with volume contraction and a deterioration in renal function, as seen with long-term diuretic use. This is the opposite of what is seen with the use of SGLT2-inhibitors, which are associated with long-term preservation of renal function. There is now growing evidence that the increase in hematocrit can be attributed to an increase in erythropoiesis due to amelioration of renal hypoxia and more efficient erythropoietin production with SGLT2-inhibitor treatment. Increased erythropoiesis leads to an increase in RBC count which improves myocardial/renal tissue oxygenation and function. CONCLUSION The increase in hematocrit with SGLT2i treatment is not due to hemoconcentration, but to an increase in erythropoiesis due to amelioration of hypoxia and more efficient erythropoietin production with SGLT2i treatment.
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Affiliation(s)
- Preethika Ekanayake
- Veterans Affairs Medical Center, San Diego, CA, USA; Department of Medicine, University of California, San Diego School of Medicine, USA
| | - Sunder Mudaliar
- Veterans Affairs Medical Center, San Diego, CA, USA; Department of Medicine, University of California, San Diego School of Medicine, USA.
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Klonoff DC, Xu NY, Nguyen KT, Kerr D, Mehta C, Umpierrez GE, Brooks GA. Trimetazidine Blocks Lipid Oxidation-Should it be Repurposed for Prevention and Treatment of Diabetic Ketoacidosis? J Diabetes Sci Technol 2022; 16:1063-1068. [PMID: 35652624 PMCID: PMC9445353 DOI: 10.1177/19322968221100196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- David C. Klonoff
- Diabetes Research Institute, Mills-Peninsula Medical Center, San Mateo, CA, USA
| | - Nicole Y. Xu
- Diabetes Technology Society, Burlingame, CA, USA
| | | | - David Kerr
- Sansum Diabetes Research Institute, Santa Barbara, CA, USA
| | - Chhavi Mehta
- Palo Alto Foundation Medical Group, Burlingame, CA, USA
| | | | - George A. Brooks
- Integrative Biology, University of California, Berkeley, Berkeley, CA, USA
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Lingli X, Wenfang X. Characteristics and molecular mechanisms through which SGLT2 inhibitors improve metabolic diseases: A mechanism review. Life Sci 2022; 300:120543. [PMID: 35421452 DOI: 10.1016/j.lfs.2022.120543] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 11/26/2022]
Abstract
Metabolic diseases, such as diabetes, gout and hyperlipidemia are global health challenges. Among them, diabetes has been extensively investigated. Type 2 diabetes mellitus (T2DM), which is characterized by hyperglycemia, is a complex metabolic disease that is associated with various metabolic disorders. The newly developed oral hypoglycemic agent, sodium-glucose cotransporter 2 (SGLT2) inhibitor, has been associated with glucose-lowering effects and it affects metabolism in various ways. However, the potential mechanisms of SGLT2 inhibitors in metabolic diseases have not fully reviewed. Many of the effects beyond glycemic control must be considered off-target effects. Therefore, we reviewed the effects of SGLT2 inhibition on metabolic diseases such as obesity, hypertension, hyperlipidemia, hyperuricemia, fatty liver disease, insulin resistance, osteoporosis and fractures. Moreover, we elucidated their molecular mechanisms to provide a theoretical basis for metabolic disease treatment.
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Affiliation(s)
- Xie Lingli
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Hubei Provincial Clinical Research Center for Diabetes and Metabolic Disorders, Wuhan, China
| | - Xia Wenfang
- Department of Endocrinology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Hubei Provincial Clinical Research Center for Diabetes and Metabolic Disorders, Wuhan, China.
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Xie J, Zhong F, Guo Z, Li X, Wang J, Gao Z, Chang B, Yang J. Hyperinsulinemia impairs the metabolic switch to ketone body utilization in proximal renal tubular epithelial cells under energy crisis via the inhibition of the SIRT3/SMCT1 pathway. Front Endocrinol (Lausanne) 2022; 13:960835. [PMID: 36237185 PMCID: PMC9551351 DOI: 10.3389/fendo.2022.960835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 08/31/2022] [Indexed: 12/05/2022] Open
Abstract
OBJECTIVE To investigate the effects and mechanism of hyperinsulinemia on the metabolic switch to β-hydroxybutyrate (BHB) absorption and utilization under a starvation or hypoxic environment in proximal tubular epithelial cells. METHODS A high-fat diet-induced hyperinsulinemia model in ZDF rats was used to test the expression of key enzymes/proteins of ketone body metabolism in the kidney. Notably, 12-week-old renal tubule SMCT1 specific knockout mice (SMCT1 flox/floxCre+) and control mice (SMCT1 flox/floxCre-) were used to confirm the roles of SMCT1 in kidney protection under starvation. The changes of key enzymes/proteins of energy metabolism, mitochondrial function, and albumin endocytosis in HK2 cells under low glucose/hypoxic environments with or without 50 ng/mL insulin were studied. Silent information regulation 2 homolog 3 (SIRT3) was overexpressed to evaluate the effect of hyperinsulinemia on the metabolic switch to BHB absorption and utilization through the SIRT3/SMCT1 pathway in HK2 cells. RESULTS In ZDF rats, the expression of HMGCS2 increased, the SMCT1 expression decreased, while SCOT remained unchanged. In renal tubule SMCT1 gene-specific knockout mice, starvation for 48 h induced an increase in the levels of urine retinol-binding protein, N-acetyl-β-glucosaminidase, and transferrin, which reflected tubular damages. In HK2 cells under an environment of starvation and hypoxia, the levels of key enzymes related to fatty acid oxidation and ketone body metabolism were increased, whereas glucose glycolysis did not change. The addition of 2 mmol/l BHB improved ATP production, mitochondrial biosynthesis, and endocytic albumin function, while cell apoptosis was reduced in HK2 cells. The addition of 50 ng/ml insulin resulted in the decreased expression of SMCT1 along with an impaired mitochondrial function, decreased ATP production, and increased apoptosis. The overexpression of SIRT3 or SMCT1 reversed these alterations induced by a high level of insulin both in low-glucose and hypoxic environments. CONCLUSIONS The increased absorption and utilization of BHB is part of the metabolic flexibility of renal tubular epithelial cells under starvation and hypoxic environments, which exhibits a protective effect on renal tubular epithelial cells by improving the mitochondrial function and cell survival. Moreover, hyperinsulinemia inhibits the absorption of BHB through the inhibition of the SIRT3/SMCT1 pathway.
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Affiliation(s)
| | | | | | | | | | | | | | - Juhong Yang
- *Correspondence: Juhong Yang, ; Baocheng Chang,
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