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Duan HY, Barajas-Martinez H, Antzelevitch C, Hu D. The potential anti-arrhythmic effect of SGLT2 inhibitors. Cardiovasc Diabetol 2024; 23:252. [PMID: 39010053 PMCID: PMC11251349 DOI: 10.1186/s12933-024-02312-0] [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: 04/11/2024] [Accepted: 06/16/2024] [Indexed: 07/17/2024] Open
Abstract
Sodium-glucose cotransporter type 2 inhibitors (SGLT2i) were initially recommended as oral anti-diabetic drugs to treat type 2 diabetes (T2D), by inhibiting SGLT2 in proximal tubule and reduce renal reabsorption of sodium and glucose. While many clinical trials demonstrated the tremendous potential of SGLT2i for cardiovascular diseases. 2022 AHA/ACC/HFSA guideline first emphasized that SGLT2i were the only drug class that can cover the entire management of heart failure (HF) from prevention to treatment. Subsequently, the antiarrhythmic properties of SGLT2i have also attracted attention. Although there are currently no prospective studies specifically on the anti-arrhythmic effects of SGLT2i. We provide clues from clinical and fundamental researches to identify its antiarrhythmic effects, reviewing the evidences and mechanism for the SGLT2i antiarrhythmic effects and establishing a novel paradigm involving intracellular sodium, metabolism and autophagy to investigate the potential mechanisms of SGLT2i in mitigating arrhythmias.
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Affiliation(s)
- Hong-Yi Duan
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, 238 Jiefang Road, Wuhan, 430060, Hubei, China
- Hubei Key Laboratory of Cardiology, Wuhan, 430060, Hubei, China
| | - Hector Barajas-Martinez
- Lankenau Institute for Medical Research, Lankenau Heart Institute, Wynnewood, PA, 19096, USA
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, 19107, USA
| | - Charles Antzelevitch
- Lankenau Institute for Medical Research, Lankenau Heart Institute, Wynnewood, PA, 19096, USA
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, 19107, USA
| | - Dan Hu
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, 238 Jiefang Road, Wuhan, 430060, Hubei, China.
- Hubei Key Laboratory of Cardiology, Wuhan, 430060, Hubei, China.
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Darshi M, Kugathasan L, Maity S, Sridhar VS, Fernandez R, Limonte CP, Grajeda BI, Saliba A, Zhang G, Drel VR, Kim JJ, Montellano R, Tumova J, Montemayor D, Wang Z, Liu JJ, Wang J, Perkins BA, Lytvyn Y, Natarajan L, Lim SC, Feldman H, Toto R, Sedor JR, Patel J, Waikar SS, Brown J, Osman Y, He J, Chen J, Reeves WB, de Boer IH, Roy S, Vallon V, Hallan S, Gelfond JA, Cherney DZ, Sharma K. Glycolytic lactate in diabetic kidney disease. JCI Insight 2024; 9:e168825. [PMID: 38855868 DOI: 10.1172/jci.insight.168825] [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: 05/08/2023] [Accepted: 05/01/2024] [Indexed: 06/11/2024] Open
Abstract
Lactate elevation is a well-characterized biomarker of mitochondrial dysfunction, but its role in diabetic kidney disease (DKD) is not well defined. Urine lactate was measured in patients with type 2 diabetes (T2D) in 3 cohorts (HUNT3, SMART2D, CRIC). Urine and plasma lactate were measured during euglycemic and hyperglycemic clamps in participants with type 1 diabetes (T1D). Patients in the HUNT3 cohort with DKD had elevated urine lactate levels compared with age- and sex-matched controls. In patients in the SMART2D and CRIC cohorts, the third tertile of urine lactate/creatinine was associated with more rapid estimated glomerular filtration rate decline, relative to first tertile. Patients with T1D demonstrated a strong association between glucose and lactate in both plasma and urine. Glucose-stimulated lactate likely derives in part from proximal tubular cells, since lactate production was attenuated with sodium-glucose cotransporter-2 (SGLT2) inhibition in kidney sections and in SGLT2-deficient mice. Several glycolytic genes were elevated in human diabetic proximal tubules. Lactate levels above 2.5 mM potently inhibited mitochondrial oxidative phosphorylation in human proximal tubule (HK2) cells. We conclude that increased lactate production under diabetic conditions can contribute to mitochondrial dysfunction and become a feed-forward component to DKD pathogenesis.
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Affiliation(s)
- Manjula Darshi
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Luxcia Kugathasan
- Division of Nephrology, Department of Medicine, University Health Network, Toronto, Canada
| | - Soumya Maity
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Vikas S Sridhar
- Division of Nephrology, Department of Medicine, University Health Network, Toronto, Canada
| | - Roman Fernandez
- Department of Population Health Sciences, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Christine P Limonte
- Schools of Medicine and Public Health, University of Washington, Seattle, Washington, USA
| | - Brian I Grajeda
- Department of Biological Sciences and Border Biomedical Research Center, University of Texas at El Paso, El Paso, Texas, USA
| | - Afaf Saliba
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Guanshi Zhang
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Viktor R Drel
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Jiwan J Kim
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Richard Montellano
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Jana Tumova
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Daniel Montemayor
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Zhu Wang
- Department of Population Health Sciences, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Jian-Jun Liu
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore
| | - Jiexun Wang
- Clinical Research Unit, Khoo Teck Puat Hospital, Singapore
| | - Bruce A Perkins
- Division of Nephrology, Department of Medicine, University Health Network, Toronto, Canada
| | - Yuliya Lytvyn
- Division of Nephrology, Department of Medicine, University Health Network, Toronto, Canada
| | - Loki Natarajan
- Herbert Wertheim School of Public Health, University of California, San Diego, La Jolla, California USA
| | - Su Chi Lim
- Clinical Research Unit & Admiralty Medical Centre, Khoo Teck Puat Hospital, Singapore
- Saw Swee Hock School of Public Heath, National University of Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore
| | - Harold Feldman
- Center for Clinical Epidemiology and Biostatistics and
- Department of Biostatistics, Epidemiology, and Informatics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Robert Toto
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Texas, USA
| | - John R Sedor
- Glickman Urology and Kidney and Lerner Research Institutes, Cleveland Clinic, Cleveland, Ohio, USA
| | - Jiten Patel
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Texas, USA
| | - Sushrut S Waikar
- Section of Nephrology, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts, USA
| | - Julia Brown
- Division of Nephrology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Yahya Osman
- Division of Nephrology, Department of Medicine, Wayne State University, Detroit, Michigan, USA
| | - Jiang He
- School of Public Health, Tulane University Medical Center, New Orleans, Louisiana, USA
| | - Jing Chen
- Division of Nephrology, Department of Medicine, New Orleans, Louisiana, USA
| | - W Brian Reeves
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Ian H de Boer
- Schools of Medicine and Public Health, University of Washington, Seattle, Washington, USA
| | - Sourav Roy
- Department of Biological Sciences and Border Biomedical Research Center, University of Texas at El Paso, El Paso, Texas, USA
| | - Volker Vallon
- Department of Medicine, University of California, San Diego, La Jolla, California, USA
- VA San Diego Healthcare Center, San Diego, California, USA
| | - Stein Hallan
- Department of Clinical and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway
- Department of Nephrology, St. Olav Hospital, Trondheim, Norway
| | - Jonathan Al Gelfond
- Department of Population Health Sciences, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - David Zi Cherney
- Division of Nephrology, Department of Medicine, University Health Network, Toronto, Canada
| | - Kumar Sharma
- Center for Precision Medicine, Division of Nephrology, Department of Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
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Albalawy WN, Youm EB, Shipman KE, Trull KJ, Baty CJ, Long KR, Rbaibi Y, Wang XP, Fagunloye OG, White KA, Jurczak MJ, Kashlan OB, Weisz OA. SGLT2-independent effects of canagliflozin on NHE3 and mitochondrial complex I activity inhibit proximal tubule fluid transport and albumin uptake. Am J Physiol Renal Physiol 2024; 326:F1041-F1053. [PMID: 38660713 DOI: 10.1152/ajprenal.00005.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 04/03/2024] [Accepted: 04/18/2024] [Indexed: 04/26/2024] Open
Abstract
Beyond glycemic control, SGLT2 inhibitors (SGLT2is) have protective effects on cardiorenal function. Renoprotection has been suggested to involve inhibition of NHE3 leading to reduced ATP-dependent tubular workload and mitochondrial oxygen consumption. NHE3 activity is also important for regulation of endosomal pH, but the effects of SGLT2i on endocytosis are unknown. We used a highly differentiated cell culture model of proximal tubule (PT) cells to determine the direct effects of SGLT2i on Na+-dependent fluid transport and endocytic uptake in this nephron segment. Strikingly, canagliflozin but not empagliflozin reduced fluid transport across cell monolayers and dramatically inhibited endocytic uptake of albumin. These effects were independent of glucose and occurred at clinically relevant concentrations of drug. Canagliflozin acutely inhibited surface NHE3 activity, consistent with a direct effect, but did not affect endosomal pH or NHE3 phosphorylation. In addition, canagliflozin rapidly and selectively inhibited mitochondrial complex I activity. Inhibition of mitochondrial complex I by metformin recapitulated the effects of canagliflozin on endocytosis and fluid transport, whereas modulation of downstream effectors AMPK and mTOR did not. Mice given a single dose of canagliflozin excreted twice as much urine over 24 h compared with empagliflozin-treated mice despite similar water intake. We conclude that canagliflozin selectively suppresses Na+-dependent fluid transport and albumin uptake in PT cells via direct inhibition of NHE3 and of mitochondrial function upstream of the AMPK/mTOR axis. These additional targets of canagliflozin contribute significantly to reduced PT Na+-dependent fluid transport in vivo.NEW & NOTEWORTHY Reduced NHE3-mediated Na+ transport has been suggested to underlie the cardiorenal protection provided by SGLT2 inhibitors. We found that canagliflozin, but not empagliflozin, reduced NHE3-dependent fluid transport and endocytic uptake in cultured proximal tubule cells. These effects were independent of SGLT2 activity and resulted from inhibition of mitochondrial complex I and NHE3. Studies in mice are consistent with greater effects of canagliflozin versus empagliflozin on fluid transport. Our data suggest that these selective effects of canagliflozin contribute to reduced Na+-dependent transport in proximal tubule cells.
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Affiliation(s)
- Wafaa N Albalawy
- Department of Human Genetics, Pitt Public Health, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Elynna B Youm
- Department of Human Genetics, Pitt Public Health, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Katherine E Shipman
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Keelan J Trull
- Department of Chemistry and Biochemistry, University of Notre Dame, South Bend, Indiana, United States
| | - Catherine J Baty
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Kimberly R Long
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Youssef Rbaibi
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Xue-Ping Wang
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Olayemi G Fagunloye
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Katharine A White
- Department of Chemistry and Biochemistry, University of Notre Dame, South Bend, Indiana, United States
| | - Michael J Jurczak
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Ossama B Kashlan
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
| | - Ora A Weisz
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States
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Dominguez Rieg JA, Rieg T. New functions and roles of the Na +-H +-exchanger NHE3. Pflugers Arch 2024; 476:505-516. [PMID: 38448727 DOI: 10.1007/s00424-024-02938-9] [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: 02/05/2024] [Revised: 02/22/2024] [Accepted: 02/27/2024] [Indexed: 03/08/2024]
Abstract
The sodium/proton exchanger isoform 3 (NHE3) is expressed in the intestine and the kidney, where it contributes to hydrogen secretion and sodium (re)absorption. The roles of this transporter have been studied by the use of the respective knockout mice and by using pharmacological inhibitors. Whole-body NHE3 knockout mice suffer from a high mortality rate (with only ∼30% of mice surviving into adulthood), and based on the expression of NHE3 in both intestine and kidney, some conclusions that were originally derived were based on this rather complex phenotype. In the last decade, more refined models have been developed that added temporal and spatial control of NHE3 expression. For example, novel mouse models have been developed with a knockout of NHE3 in intestinal epithelial cells, tubule/collecting duct of the kidney, proximal tubule of the kidney, and thick ascending limb of the kidney. These refined models have significantly contributed to our understanding of the role of NHE3 in a tissue/cell type-specific manner. In addition, tenapanor was developed, which is a non-absorbable, intestine-specific NHE3 inhibitor. In rat and human studies, tenapanor lowered intestinal Pi uptake and was effective in lowering plasma Pi levels in patients on hemodialysis. Of note, diarrhea is seen as a side effect of tenapanor (with its indication for the treatment of constipation) and in intestine-specific NHE3 knockout mice; however, effects on plasma Pi were not supported by this mouse model which showed enhanced and not reduced intestinal Pi uptake. Further studies indicated that the gut microbiome in mice lacking intestinal NHE3 resembles an intestinal environment favoring the competitive advantage of inflammophilic over anti-inflammatory species, something similar seen in patients with inflammatory bowel disease. This review will highlight recent developments and summarize newly gained insight from these refined models.
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Affiliation(s)
- Jessica A Dominguez Rieg
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA
- James A. Haley Veterans' Hospital, Tampa, FL, 33612, USA
- Hypertension and Kidney Research Center, University of South Florida, Tampa, FL, 33602, USA
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, FL, 33612, USA.
- James A. Haley Veterans' Hospital, Tampa, FL, 33612, USA.
- Hypertension and Kidney Research Center, University of South Florida, Tampa, FL, 33602, USA.
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Kazory A. Contemporary Decongestive Strategies in Acute Heart Failure. Semin Nephrol 2024; 44:151512. [PMID: 38702211 DOI: 10.1016/j.semnephrol.2024.151512] [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] [Indexed: 05/06/2024]
Abstract
Congestion is the primary driver of hospital admissions in patients with heart failure and the key determinant of their outcome. Although intravenous loop diuretics remain the predominant agents used in the setting of acute heart failure, the therapeutic response is known to be variable, with a significant subset of patients discharged from the hospital with residual hypervolemia. In this context, urinary sodium excretion has gained attention both as a marker of response to loop diuretics and as a marker of prognosis that may be a useful clinical tool to guide therapy. Several decongestive strategies have been explored to improve diuretic responsiveness and removal of excess fluid. Sequential nephron blockade through combination diuretic therapy is one of the most used methods to enhance natriuresis and counter diuretic resistance. In this article, I provide an overview of the contemporary decongestive approaches and discuss the clinical data on the use of add-on diuretic therapy. I also discuss mechanical removal of excess fluid through extracorporeal ultrafiltration with a brief review of the results of landmark studies. Finally, I provide a short overview of the strategies that are currently under investigation and may prove helpful in this setting.
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Affiliation(s)
- Amir Kazory
- Division of Nephrology, Hypertension, and Renal Transplantation, College of Medicine, University of Florida, Gainesville, FL.
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Zeng XC, Tian Y, Liang XM, Wu XB, Yao CM, Chen XM. SGLT2i relieve proteinuria in diabetic nephropathy patients potentially by inhibiting renal oxidative stress rather than through AGEs pathway. Diabetol Metab Syndr 2024; 16:46. [PMID: 38365853 PMCID: PMC10870536 DOI: 10.1186/s13098-024-01280-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Accepted: 01/31/2024] [Indexed: 02/18/2024] Open
Abstract
AIMS To estimate the effects of the sodium-glucose cotransporter 2 inhibitor (SGLT2i) on proteinuria and oxidative stress expression in type 2 diabetes patients. MATERIALS AND METHODS 68 patients with type 2 diabetes mellitus (T2DM) were divided into three groups according urinary albumin-to-creatinine ratio (UACR), including T2DM with non-albuminuria group (UACR < 30 mg/g), T2DM with microalbuminuria group (30 ≤ UACR ≤ 300 mg/g), T2DM with macroalbuminuria group (UACR>300 mg/g). They all received SGLT2 inhibitors (SGLT2i) treatment for 12 weeks. The expression of advanced glycation end products (AGEs) in plasma and 8-hydroxy-2-deoxyguanosine (8-OHdG) in urine were measured as indications of oxidative stress. The 24-hour urine samples were collected to measure the concentration of proteinuria and 8-OHdG before and after 12 weeks SGLT2i treatment. Plasma renin activity (PRA), angiotensin II (Ang II) and Aldosterone (ALD) were measured to evaluate renin angiotensin aldosterone system (RASS) levels. RESULTS After 12 weeks SGLT2 inhibitors treatment, the median values of 24-hour proteinuria decreased in macroalbuminuria compared to baseline (970 vs. 821 mg/d, P = 0.006). The median values of AGEs and 8-OHdG decreased in microalbuminuria and macroalbuminuria groups when compared to baseline, AGEs (777 vs. 136 ug/ml, P = 0.003) and (755 vs. 210 ug/ml, P = 0.001), 8-OHdG (8.00 vs. 1.88 ng/ml, P = 0.001) and (11.18 vs. 1.90 ng/ml, P < 0.001), respectively. Partial correlations showed that 8-OHdG were relevant to the baseline 24-h proteinuria (r = 0.389, p = 0.001), the reduction of OHdG (Δ8-OHdG) were positively correlated with the decrease of 24-h proteinuria (Δ24-h proteinuria) after 12 weeks of SGLT2i treatment (r = 0.283, P = 0.031). There was no significant correlation between 24-h proteinuria and AGEs in baseline (r = -0.059, p = 0.640) as well as between ΔAGEs and Δ24-h proteinuria (r = 0.022, p = 0.872) after12 weeks of SGLT2i treatment in T2DM patients. CONCLUSIONS SGLT2i may reduce proteinuria in diabetic nephropathy patients, potentially by inhibiting renal oxidative stress, but not through the AGEs pathway and does not induce RAAS activation. TRIAL REGISTRATION This clinical trial was registered on 15/10/2019, in ClinicalTrials.gov, and the registry number is NCT04127084.
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Affiliation(s)
- Xiao-Chun Zeng
- Department of Endocrinology and Metabolism, School of Medicine, Zhongshan Hospital of Xiamen University, Xiamen University, 201-209 Hubin South Road, 361004, Xiamen, P.R. China
- The School of Clinical Medicine, Fujian Medical University, 350004, Fuzhou, P.R. China
| | - Yuan Tian
- Department of Endocrinology and Metabolism, School of Medicine, Zhongshan Hospital of Xiamen University, Xiamen University, 201-209 Hubin South Road, 361004, Xiamen, P.R. China
| | - Xian-Ming Liang
- Center of Clinical Laboratory, School of Medicine, Zhongshan Hospital of Xiamen University, Xiamen University, 201-209 Hubin South Road, 361004, Xiamen, P. R. China
| | - Xiao-Bin Wu
- Department of Endocrinology and Metabolism, School of Medicine, Zhongshan Hospital of Xiamen University, Xiamen University, 201-209 Hubin South Road, 361004, Xiamen, P.R. China
| | - Chun-Meng Yao
- Department of Nephrology, School of Medicine, Zhongshan Hospital of Xiamen University, Xiamen University, 201-209 Hubin South Road, 361004, Xiamen, P. R. China
| | - Xiao-Min Chen
- Department of Endocrinology and Metabolism, School of Medicine, Zhongshan Hospital of Xiamen University, Xiamen University, 201-209 Hubin South Road, 361004, Xiamen, P.R. China.
- The School of Clinical Medicine, Fujian Medical University, 350004, Fuzhou, P.R. China.
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Huang Z, Cao M, Fan H, Sun Y, Lan T, Ma J, Li Q. Porcine delta coronavirus inhibits NHE3 activity of porcine intestinal epithelial cells through miR-361-3p/NHE3 regulatory axis. Vet Microbiol 2024; 289:109916. [PMID: 38159369 DOI: 10.1016/j.vetmic.2023.109916] [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: 08/02/2023] [Revised: 11/05/2023] [Accepted: 11/17/2023] [Indexed: 01/03/2024]
Abstract
Porcine deltacoronavirus (PDCoV) infection in piglets can cause small intestinal epithelial necrosis and atrophic enteritis, which leads to severe damages to host cells, and result in diarrhea. In this study, we investigated the relationship between miR-361, SLC9A3(Solute carrier family 9, subfamily A, member 3), and NHE3(sodium-hydrogen exchanger member 3) in in porcine intestinal epithelial cells (IPI-2I) cells after PDCoV infection. Our results showed that the ssc-miR-361-3p expression inhibits the mRNA level of SLC9A3 gene which lead to the descending of NHE3 protein expression, and the NHE3 activity was suppressed. NHE3 activity was suppressed via down-regulation expression of SLC9A3 mRNA by transfection with siRNA. Ssc-miR-361-3p mimics and inhibitors were used to change the expression of ssc-miR-361-3p in IPI-2I cells. Ssc-miR-361-3p overexpression reduced the mRNA level of SLC9A3 gene, the level of NHE3 protein expression and NHE3 activity in IPI-2I cells, while ssc-miR-361-3p inhibits NHE3. Furthermore, luciferase reporter assay showed that SLC9A3 gene was a direct target of ssc-miR-361-3p. Ssc-miR-361-3p inhibition restored NHE3 activity in PDCoV infected IPI-2I cells by up-regulating SLC9A3 mRNA expression and NHE3 protein expression. These results demonstrate that the PDCoV infection can inhibit NHE3 activity through miR-361-3p/SLC9A3 regulatory axis. The relevant research is reported for the first time in PDCoV, which has significance in exploring the pathogenic mechanism of PDCoV and can provide a theoretical basis for its prevention and control. suggesting that NHE3 and ssc-miR-361-3p may be potential therapeutic targets for diarrhea in infected piglets.
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Affiliation(s)
- Zehong Huang
- State Key Laboratory of Swine and Poultry Breeding Industry, Guangzhou 510642, China
| | - Mengjing Cao
- State Key Laboratory of Swine and Poultry Breeding Industry, Guangzhou 510642, China
| | - Haoqian Fan
- State Key Laboratory of Swine and Poultry Breeding Industry, Guangzhou 510642, China
| | - Yuan Sun
- State Key Laboratory of Swine and Poultry Breeding Industry, Guangzhou 510642, China
| | - Tian Lan
- State Key Laboratory of Swine and Poultry Breeding Industry, Guangzhou 510642, China
| | - Jingyun Ma
- State Key Laboratory of Swine and Poultry Breeding Industry, Guangzhou 510642, China.
| | - Qianniu Li
- State Key Laboratory of Swine and Poultry Breeding Industry, Guangzhou 510642, China.
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8
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Kazory A. Combination Diuretic Therapy to Counter Renal Sodium Avidity in Acute Heart Failure: Trials and Tribulations. Clin J Am Soc Nephrol 2023; 18:1372-1381. [PMID: 37102974 PMCID: PMC10578637 DOI: 10.2215/cjn.0000000000000188] [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: 02/17/2023] [Accepted: 04/20/2023] [Indexed: 04/28/2023]
Abstract
In contrast to significant advances in the management of patients with chronic heart failure over the past few years, there has been little change in how patients with acute heart failure are treated. Symptoms and signs of fluid overload are the primary reason for hospitalization of patients who experience acute decompensation of heart failure. Intravenous loop diuretics remain the mainstay of therapy in this patient population, with a significant subset of them showing suboptimal response to these agents leading to incomplete decongestion at the time of discharge. Combination diuretic therapy, that is, using loop diuretics along with an add-on agent, is a widely applied strategy to counter renal sodium avidity through sequential blockade of sodium absorption within renal tubules. The choice of the second diuretic is affected by several factors, including the site of action, the anticipated secondary effects, and the available evidence on their efficacy and safety. While the current guidelines recommend combination diuretic therapy as a viable option to overcome suboptimal response to loop diuretics, it is also acknowledged that this strategy is not supported by strong evidence and remains an area of uncertainty. The recent publication of landmark studies has regenerated the interest in sequential nephron blockade. In this article, we provide an overview of the results of the key studies on combination diuretic therapy in the setting of acute heart failure and discuss their findings primarily with regard to the effect on renal sodium avidity and cardiorenal outcomes.
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Affiliation(s)
- Amir Kazory
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida, Gainesville, Florida
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9
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Packer M. Fetal Reprogramming of Nutrient Surplus Signaling, O-GlcNAcylation, and the Evolution of CKD. J Am Soc Nephrol 2023; 34:1480-1491. [PMID: 37340541 PMCID: PMC10482065 DOI: 10.1681/asn.0000000000000177] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 06/07/2023] [Indexed: 06/22/2023] Open
Abstract
ABSTRACT Fetal kidney development is characterized by increased uptake of glucose, ATP production by glycolysis, and upregulation of mammalian target of rapamycin (mTOR) and hypoxia-inducible factor-1 alpha (HIF-1 α ), which (acting in concert) promote nephrogenesis in a hypoxic low-tubular-workload environment. By contrast, the healthy adult kidney is characterized by upregulation of sirtuin-1 and adenosine monophosphate-activated protein kinase, which enhances ATP production through fatty acid oxidation to fulfill the needs of a normoxic high-tubular-workload environment. During stress or injury, the kidney reverts to a fetal signaling program, which is adaptive in the short term, but is deleterious if sustained for prolonged periods when both oxygen tension and tubular workload are heightened. Prolonged increases in glucose uptake in glomerular and proximal tubular cells lead to enhanced flux through the hexosamine biosynthesis pathway; its end product-uridine diphosphate N -acetylglucosamine-drives the rapid and reversible O-GlcNAcylation of thousands of intracellular proteins, typically those that are not membrane-bound or secreted. Both O-GlcNAcylation and phosphorylation act at serine/threonine residues, but whereas phosphorylation is regulated by hundreds of specific kinases and phosphatases, O-GlcNAcylation is regulated only by O-GlcNAc transferase and O-GlcNAcase, which adds or removes N-acetylglucosamine, respectively, from target proteins. Diabetic and nondiabetic CKD is characterized by fetal reprogramming (with upregulation of mTOR and HIF-1 α ) and increased O-GlcNAcylation, both experimentally and clinically. Augmentation of O-GlcNAcylation in the adult kidney enhances oxidative stress, cell cycle entry, apoptosis, and activation of proinflammatory and profibrotic pathways, and it inhibits megalin-mediated albumin endocytosis in glomerular mesangial and proximal tubular cells-effects that can be aggravated and attenuated by augmentation and muting of O-GlcNAcylation, respectively. In addition, drugs with known nephroprotective effects-angiotensin receptor blockers, mineralocorticoid receptor antagonists, and sodium-glucose cotransporter 2 inhibitors-are accompanied by diminished O-GlcNAcylation in the kidney, although the role of such suppression in mediating their benefits has not been explored. The available evidence supports further work on the role of uridine diphosphate N -acetylglucosamine as a critical nutrient surplus sensor (acting in concert with upregulated mTOR and HIF-1 α signaling) in the development of diabetic and nondiabetic CKD.
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Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute , Dallas , Texas and Imperial College , London , United Kingdom
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10
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Forzano I, Wilson S, Lombardi A, Jankauskas SS, Kansakar U, Mone P, Varzideh F, Santulli G. SGLT2 inhibitors: an evidence-based update on cardiovascular implications. Expert Opin Investig Drugs 2023; 32:839-847. [PMID: 37740906 PMCID: PMC10591907 DOI: 10.1080/13543784.2023.2263354] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 09/22/2023] [Indexed: 09/25/2023]
Abstract
INTRODUCTION Sodium Glucose co-Transporter 2 (SGLT2) inhibitors (also known as 'gliflozins') represent a cornerstone to treat diabetes mellitus. Moreover, recent randomized clinical trials have demonstrated important cardioprotective effects of gliflozins, independent of the presence of diabetes. Herein, we summarize the recent therapeutic progress in the cardiovascular field obtained with SGLT2 inhibitors. AREA COVERED We critically examine the rationale and results of recent clinical studies examining the effects of SGLT2 inhibitors on cardiovascular outcomes, along with a brief overview of the main ongoing trials that have been designed in order to answer the many pending questions in the field of gliflozins and cardiovascular disease. EXPERT OPINION The favorable results of several clinical trials have broadened the therapeutic scenario for SGLT2 inhibitors, opening, at the same time, new challenges. Additionally, recent preclinical findings have evidenced off-target effects of SGLT2 inhibitors.
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Affiliation(s)
| | - Scott Wilson
- Department of Medicine, Albert Einstein College of Medicine, New York City, NY, USA
| | - Angela Lombardi
- Department of Medicine, Albert Einstein College of Medicine, New York City, NY, USA
| | | | - Urna Kansakar
- Department of Medicine, Albert Einstein College of Medicine, New York City, NY, USA
| | - Pasquale Mone
- Department of Medicine, Albert Einstein College of Medicine, New York City, NY, USA
| | - Fahimeh Varzideh
- Department of Medicine, Albert Einstein College of Medicine, New York City, NY, USA
| | - Gaetano Santulli
- University of Naples “Federico II”
- Department of Medicine, Albert Einstein College of Medicine, New York City, NY, USA
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11
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Tang H, Xu C, Zhang P, Luo T, Huang Y, Yang X. A profile of SGLT-2 inhibitors in hyponatremia: The evidence to date. Eur J Pharm Sci 2023; 184:106415. [PMID: 36870579 DOI: 10.1016/j.ejps.2023.106415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 02/14/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023]
Abstract
Hyponatremia is the most common electrolyte disorder in clinical practice, which may lead to life-threatening complications. Several lines of evidence suggest that hyponatremia is associated not only with significant increases in length of stay, cost, and financial burden, but also with increased morbidity and mortality. Hyponatremia is also considered to be a negative prognostic factor in patients with heart failure and cancer. Although multiple therapeutic methods are available for treating hyponatremia, most have some limitations, such as poor compliance, rapid correction of serum Na+, other negative side effects and high cost. Given these limitations, identifying novel therapies for hyponatremia is essential. Recent clinical studies have shown that SGLT-2 inhibitors (SGLT 2i) significantly increased serum Na+ levels and were well tolerated by patients who underwent this treatment. Therefore, oral administration of SGLT 2i appears to be an effective treatment for hyponatremia. This article will briefly review the etiology of hyponatremia and integrated control of sodium within the kidney, current therapies for hyponatremia, potential mechanisms and efficacy of SGLT 2i for hyponatremia, and the benefits in cardiovascular, cancer, and kidney disease by regulating sodium and water balance.
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Affiliation(s)
- Hui Tang
- Department of Pharmacy, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China; School of Pharmacy, Southwest Medical University, Luzhou 646000, China
| | - Changjing Xu
- Department of Pharmacy, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China
| | - Piao Zhang
- Department of Pharmacy, Ya 'an People's Hospital, Ya 'an, Sichuan 646000, China
| | - Taimin Luo
- Department of pharmacy, Chengdu Seventh People's Hospital, Chengdu, Sichuan 610000, China
| | - Yilan Huang
- Department of Pharmacy, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China; School of Pharmacy, Southwest Medical University, Luzhou 646000, China.
| | - Xuping Yang
- Department of Pharmacy, The Affiliated Hospital of Southwest Medical University, Luzhou 646000, China; School of Pharmacy, Southwest Medical University, Luzhou 646000, China.
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12
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Park J, Seo E, Jun HS. Bavachin alleviates diabetic nephropathy in db/db mice by inhibition of oxidative stress and improvement of mitochondria function. Biomed Pharmacother 2023; 161:114479. [PMID: 36921531 DOI: 10.1016/j.biopha.2023.114479] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/01/2023] [Accepted: 03/07/2023] [Indexed: 03/18/2023] Open
Abstract
Diabetic nephropathy (DN) is a major complication of diabetes mellitus. Psoralea corylifolia L. seed (PCS) is a traditional medicine effective against various diseases. In this study, we aimed to investigate the effect of bavachin, the major active component of PCS, on DN in db/db mice. Bavachin (10 mg/kg/day) was administered orally to 12-week-old male db/db mice for 6 wk. For in vitro experiments, SV40 MES13 cells were treated with bavachin in the presence of 25 mM glucose. Food and water intake and urine mass were significantly increased in db/db mice compared to wild-type CON mice, but bavachin administration significantly reduced these increases. Urinary microalbumin, blood urea nitrogen, and creatinine clearance which were significantly increased in db/db mice, were also decreased by bavachin administration. Glomerular area and collagen deposition in the kidney were significantly decreased in db/db mice following bavachin administration. Increased renal levels of fibrotic factors, fibronectin, COL1A1, and α-SMA, were reduced following bavachin administration. Protein expressions of antioxidant enzymes, namely SOD2, catalase, and HO-1, and mitochondrial function-related factors, namely SIRT1, PGC1α, Nrf1, and mtTFA, were reduced in the kidney tissues of db/db mice compared to wild-type CON mice, and bavachin administration upregulated these protein expressions. In vitro studies also showed that bavachin decreases mitochondria ROS production, increases the expression of PGC-1α and SIRT1, and decreases the expression of α-SMA in high glucose-treated SV40 MES13 cells. Based on these results, bavachin improved DN by inhibiting oxidative stress and enhancing mitochondrial function.
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Affiliation(s)
- Jisu Park
- College of Pharmacy and Gachon Institute of Pharmaceutical Science, Gachon University, Incheon 21936, Republic of Korea
| | - Eunhui Seo
- College of Pharmacy and Gachon Institute of Pharmaceutical Science, Gachon University, Incheon 21936, Republic of Korea; Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon 21999, Republic of Korea
| | - Hee-Sook Jun
- College of Pharmacy and Gachon Institute of Pharmaceutical Science, Gachon University, Incheon 21936, Republic of Korea; Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon 21999, Republic of Korea; Gachon Medical Research Institute, Gil Hospital, Incheon 21565, Republic of Korea.
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13
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Noroozbabaee L, Blanco PJ, Safaei S, Nickerson DP. A modular and reusable model of epithelial transport in the proximal convoluted tubule. PLoS One 2022; 17:e0275837. [PMID: 36355848 PMCID: PMC9648790 DOI: 10.1371/journal.pone.0275837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 09/24/2022] [Indexed: 11/12/2022] Open
Abstract
We review a collection of published renal epithelial transport models, from which we build a consistent and reusable mathematical model able to reproduce many observations and predictions from the literature. The flexible modular model we present here can be adapted to specific configurations of epithelial transport, and in this work we focus on transport in the proximal convoluted tubule of the renal nephron. Our mathematical model of the epithelial proximal convoluted tubule describes the cellular and subcellular mechanisms of the transporters, intracellular buffering, solute fluxes, and other processes. We provide free and open access to the Python implementation to ensure our multiscale proximal tubule model is accessible; enabling the reader to explore the model through setting their own simulations, reproducibility tests, and sensitivity analyses.
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Affiliation(s)
- Leyla Noroozbabaee
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Pablo J. Blanco
- National Laboratory for Scientific Computing, Petrópolis, Brazil
| | - Soroush Safaei
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - David P. Nickerson
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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14
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Navarro Garrido A, Kim YC, Oe Y, Zhang H, Crespo-Masip M, Goodluck HA, Kanoo S, Sanders PW, Bröer S, Vallon V. Aristolochic acid-induced nephropathy is attenuated in mice lacking the neutral amino acid transporter B 0AT1 ( Slc6a19). Am J Physiol Renal Physiol 2022; 323:F455-F467. [PMID: 35979966 PMCID: PMC9484999 DOI: 10.1152/ajprenal.00181.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 07/29/2022] [Accepted: 08/10/2022] [Indexed: 01/10/2023] Open
Abstract
B0AT1 (Slc6a19) mediates absorption of neutral amino acids in the small intestine and in the kidneys, where it is primarily expressed in early proximal tubules (S1-S2). To determine the role of B0AT1 in nephropathy induced by aristolochic acid (AA), which targets the proximal tubule, littermate female B0AT1-deficient (Slc6a19-/-), heterozygous (Slc6a19+/-), and wild-type (WT) mice were administered AA (10 mg/kg ip) or vehicle every 3 days for 3 wk, and analyses were performed after the last injection or 3 wk later. Vehicle-treated mice lacking Slc6a19 showed normal body and kidney weight and plasma creatinine versus WT mice. The urinary glucose-to-creatinine ratio (UGCR) and urinary albumin-to-creatinine ratio (UACR) were two to four times higher in vehicle-treated Slc6a19-/- versus WT mice, associated with lesser expression of early proximal transporters Na+-glucose cotransporter 2 and megalin, respectively. AA caused tubular injury independently of B0AT1, including robust increases in cortical mRNA expression of p53, p21, and hepatitis A virus cellular receptor 1 (Havcr1), downregulation of related proximal tubule amino acid transporters B0AT2 (Slc6a15), B0AT3 (Slc6a18), and Slc7a9, and modest histological tubular damage and a rise in plasma creatinine. Absence of B0AT1, however, attenuated AA-induced cortical upregulation of mRNA markers of senescence (p16), inflammation [lipocalin 2 (Lcn2), C-C motif chemokine ligand 2 (Ccl2), and C-C motif chemokine receptor 2 (Ccr2)], and fibrosis [tissue inhibitor of metallopeptidase 1 (Timp1), transforming growth factor-β1 (Tgfb1), and collagen type I-α1 (Col1a1)], associated with lesser fibrosis staining, lesser suppression of proximal tubular organic anion transporter 1, restoration of Na+-glucose cotransporter 2 expression, and prevention of the AA-induced fivefold increase in the urinary albumin-to-creatinine ratio observed in WT mice. The data suggest that proximal tubular B0AT1 is important for the physiology of renal glucose and albumin retention but potentially deleterious for the kidney response following AA-induced kidney injury.NEW & NOTEWORTHY Based on insights from studies manipulating glucose transport, the hypothesis has been proposed that inhibiting intestinal uptake or renal reabsorption of energy substrates has unique therapeutic potential to improve metabolic disease and kidney outcome in response to injury. The present study takes this idea to B0AT1, the major transporter for neutral amino acids in the intestine and kidney, and shows that its absence attenuates aristolochic acid-induced nephropathy.
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Affiliation(s)
- Aleix Navarro Garrido
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Young Chul Kim
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Yuji Oe
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Haiyan Zhang
- Department of Pathology, University of California-San Diego, San Diego, California
| | - Maria Crespo-Masip
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Helen A Goodluck
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Sadhana Kanoo
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Paul W Sanders
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Veterans Affairs Medical Center, Birmingham, Alabama
| | - Stefan Bröer
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Volker Vallon
- Department of Medicine, University of California-San Diego, La Jolla, California
- Veterans Affairs San Diego Healthcare System, San Diego, California
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15
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Abstract
SGLT2 inhibitors can protect the kidneys of patients with and without type 2 diabetes from failing. This includes blood glucose dependent and independent mechanisms. SGLT2 inhibitors lower glomerular pressure and filtration, thereby reducing the physical stress on the filtration barrier and the oxygen demand for tubular reabsorption. This improves cortical oxygenation, which, together with lesser tubular glucotoxicity and improved mitochondrial function and autophagy, can reduce proinflammatory and profibrotic signaling and preserve tubular function and GFR in long term. By shifting transport downstream, SGLT2 inhibitors may mimic systemic hypoxia and stimulate erythropoiesis, which improves oxygen delivery to the kidney and other organs.
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Affiliation(s)
- Volker Vallon
- Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA, USA; Department of Pharmacology, University of California San Diego, La Jolla, CA, USA; VA San Diego Healthcare System, 3350 La Jolla Village Drive (9151), San Diego, CA 92161, USA.
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16
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Li N, Zhou H. Sodium-glucose Cotransporter Type 2 Inhibitors: A New Insight into the Molecular Mechanisms of Diabetic Nephropathy. Curr Pharm Des 2022; 28:2131-2139. [PMID: 35718973 DOI: 10.2174/1381612828666220617153331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 03/15/2022] [Indexed: 11/22/2022]
Abstract
Diabetic nephropathy is one of the chronic microvascular complications of diabetes and is a leading cause of end-stage renal disease. Fortunately, clinical trials have demonstrated that sodium-glucose cotransporter type 2 inhibitors could decrease proteinuria and improve renal endpoints and are promising agents for the treatment of diabetic nephropathy. The renoprotective effects of sodium-glucose cotransporter type 2 inhibitors cannot be simply attributed to their advantages in aspects of metabolic benefits, such as glycemic control, lowering blood pressure, and control of serum uric acid, or improving hemodynamics associated with decreased glomerular filtration pressure. Some preclinical evidence suggests that sodium-glucose cotransporter type 2 inhibitors exert their renoprotective effects by multiple mechanisms, including attenuation of oxidative and endoplasmic reticulum stresses, anti-fibrosis and anti-inflammation, protection of podocytes, suppression of megalin function, improvement of renal hypoxia, restored mitochondrial dysfunction and autophagy, as well as inhibition of sodium-hydrogen exchanger 3. In the present study, the detailed molecular mechanisms of sodium-glucose cotransporter type 2 inhibitors with the actions of diabetic nephropathy were reviewed, with the purpose of providing the basis for drug selection for the treatment of diabetic nephropathy.
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Affiliation(s)
- Na Li
- Department of Endocrinology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
| | - Hong Zhou
- Department of Endocrinology, The Second Hospital of Hebei Medical University, Shijiazhuang, China
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17
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Oe Y, Vallon V. The Pathophysiological Basis of Diabetic Kidney Protection by Inhibition of SGLT2 and SGLT1. KIDNEY AND DIALYSIS 2022; 2:349-368. [PMID: 36380914 PMCID: PMC9648862 DOI: 10.3390/kidneydial2020032] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
SGLT2 inhibitors can protect the kidneys of patients with and without type 2 diabetes mellitus and slow the progression towards end-stage kidney disease. Blocking tubular SGLT2 and spilling glucose into the urine, which triggers a metabolic counter-regulation similar to fasting, provides unique benefits, not only as an anti-hyperglycemic strategy. These include a low hypoglycemia risk and a shift from carbohydrate to lipid utilization and mild ketogenesis, thereby reducing body weight and providing an additional energy source. SGLT2 inhibitors counteract hyperreabsorption in the early proximal tubule, which acutely lowers glomerular pressure and filtration and thereby reduces the physical stress on the filtration barrier, the filtration of tubule-toxic compounds, and the oxygen demand for tubular reabsorption. This improves cortical oxygenation, which, together with lesser tubular gluco-toxicity and improved mitochondrial function and autophagy, can reduce pro-inflammatory, pro-senescence, and pro-fibrotic signaling and preserve tubular function and GFR in the long-term. By shifting transport downstream, SGLT2 inhibitors more equally distribute the transport burden along the nephron and may mimic systemic hypoxia to stimulate erythropoiesis, which improves oxygen delivery to the kidney and other organs. SGLT1 inhibition improves glucose homeostasis by delaying intestinal glucose absorption and by increasing the release of gastrointestinal incretins. Combined SGLT1 and SGLT2 inhibition has additive effects on renal glucose excretion and blood glucose control. SGLT1 in the macula densa senses luminal glucose, which affects glomerular hemodynamics and has implications for blood pressure control. More studies are needed to better define the therapeutic potential of SGLT1 inhibition to protect the kidney, alone or in combination with SGLT2 inhibition.
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Affiliation(s)
- Yuji Oe
- Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA 92161, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Volker Vallon
- Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA 92161, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92161, USA
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18
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An Overview of the Cardiorenal Protective Mechanisms of SGLT2 Inhibitors. Int J Mol Sci 2022; 23:ijms23073651. [PMID: 35409011 PMCID: PMC8998569 DOI: 10.3390/ijms23073651] [Citation(s) in RCA: 66] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/17/2022] [Accepted: 03/24/2022] [Indexed: 02/04/2023] Open
Abstract
Sodium-glucose co-transporter 2 (SGLT2) inhibitors block glucose reabsorption in the renal proximal tubule, an insulin-independent mechanism that plays a critical role in glycemic regulation in diabetes. In addition to their glucose-lowering effects, SGLT2 inhibitors prevent both renal damage and the onset of chronic kidney disease and cardiovascular events, in particular heart failure with both reduced and preserved ejection fraction. These unexpected benefits prompted changes in treatment guidelines and scientific interest in the underlying mechanisms. Aside from the target effects of SGLT2 inhibition, a wide spectrum of beneficial actions is described for the kidney and the heart, even though the cardiac tissue does not express SGLT2 channels. Correction of cardiorenal risk factors, metabolic adjustments ameliorating myocardial substrate utilization, and optimization of ventricular loading conditions through effects on diuresis, natriuresis, and vascular function appear to be the main underlying mechanisms for the observed cardiorenal protection. Additional clinical advantages associated with using SGLT2 inhibitors are antifibrotic effects due to correction of inflammation and oxidative stress, modulation of mitochondrial function, and autophagy. Much research is required to understand the numerous and complex pathways involved in SGLT2 inhibition. This review summarizes the current known mechanisms of SGLT2-mediated cardiorenal protection.
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19
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Haruhara K, Suzuki T, Wakui H, Azushima K, Kurotaki D, Kawase W, Uneda K, Kobayashi R, Ohki K, Kinguchi S, Yamaji T, Kato I, Ohashi K, Yamashita A, Tamura T, Tsuboi N, Yokoo T, Tamura K. Deficiency of the kidney tubular angiotensin II type1 receptor-associated protein ATRAP exacerbates streptozotocin-induced diabetic glomerular injury via reducing protective macrophage polarization. Kidney Int 2022; 101:912-928. [PMID: 35240129 DOI: 10.1016/j.kint.2022.01.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 12/22/2021] [Accepted: 01/11/2022] [Indexed: 12/13/2022]
Abstract
Although activation of the renin-angiotensin system and of its glomerular components is implicated in the pathogenesis of diabetic nephropathy, the functional roles of the tubular renin-angiotensin system with AT1 receptor signaling in diabetic nephropathy are unclear. Tissue hyperactivity of the renin-angiotensin system is inhibited by the angiotensin II type 1 receptor-associated protein ATRAP, which negatively regulates receptor signaling. The highest expression of endogenous ATRAP occurs in the kidney, where it is mainly expressed by tubules but rarely in glomeruli. Here, we found that hyperactivation of angiotensin II type 1 receptor signaling in kidney tubules exacerbated diabetic glomerular injury in a mouse model of streptozotocin-induced diabetic nephropathy. These phenomena were accompanied by decreased expression of CD206, a marker of alternatively activated and tissue-reparative M2 macrophages, in the kidney tubulointerstitium. Additionally, adoptive transfer of M2- polarized macrophages into diabetic ATRAP-knockout mice ameliorated the glomerular injury. As a possible mechanism, the glomerular mRNA levels of tumor necrosis factor-α and oxidative stress components were increased in diabetic knockout mice compared to non-diabetic knockout mice, but these increases were ameliorated by adoptive transfer. Furthermore, proximal tubule-specific ATRAP downregulation reduced tubulointerstitial expression of CD206, the marker of M2 macrophages in diabetic mice. Thus, our findings indicate that tubular ATRAP-mediated functional modulation of angiotensin II type 1 receptor signaling modulates the accumulation of tubulointerstitial M2 macrophages, thus affecting glomerular manifestations of diabetic nephropathy via tubule-glomerular crosstalk.
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Affiliation(s)
- Kotaro Haruhara
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan; Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
| | - Toru Suzuki
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Hiromichi Wakui
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
| | - Kengo Azushima
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
| | - Daisuke Kurotaki
- Department of Immunology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Wataru Kawase
- Department of Immunology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Kazushi Uneda
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Ryu Kobayashi
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Kohji Ohki
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Sho Kinguchi
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Takahiro Yamaji
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan; Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore
| | - Ikuma Kato
- Department of Molecular Pathology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Kenichi Ohashi
- Department of Pathology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Akio Yamashita
- Department of Molecular Biology, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Tomohiko Tamura
- Department of Immunology, Yokohama City University Graduate School of Medicine, Yokohama, Japan; Advanced Medical Research Center, Yokohama City University, Yokohama, Japan
| | - Nobuo Tsuboi
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
| | - Takashi Yokoo
- Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Tokyo, Japan
| | - Kouichi Tamura
- Department of Medical Science and Cardiorenal Medicine, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
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20
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Cappetta D, De Angelis A, Bellocchio G, Telesca M, Cianflone E, Torella D, Rossi F, Urbanek K, Berrino L. Sodium-Glucose Cotransporter 2 Inhibitors and Heart Failure: A Bedside-to-Bench Journey. Front Cardiovasc Med 2022; 8:810791. [PMID: 35004918 PMCID: PMC8733295 DOI: 10.3389/fcvm.2021.810791] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 11/30/2021] [Indexed: 12/19/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) and heart failure (HF) are multifactorial diseases sharing common risk factors, such as obesity, hyperinsulinemia, and inflammation, with underlying mechanisms including endothelial dysfunction, inflammation, oxidative stress, and metabolic alterations. Cardiovascular benefits of sodium-glucose cotransporter 2 (SGLT2) inhibitors observed in diabetic and non-diabetic patients are also related to their cardiac-specific, SGLT-independent mechanisms, in addition to the metabolic and hemodynamic effects. In search of the possible underlying mechanisms, a research campaign has been launched proposing varied mechanisms of action that include intracellular ion homeostasis, autophagy, cell death, and inflammatory processes. Moreover, the research focus was widened toward cellular targets other than cardiomyocytes. At the moment, intracellular sodium level reduction is the most explored mechanism of direct cardiac effects of SGLT2 inhibitors that mediate the benefits in heart failure in addition to glucose excretion and diuresis. The restoration of cardiac Na+ levels with consequent positive effects on Ca2+ handling can directly translate into improved contractility and relaxation of cardiomyocytes and have antiarrhythmic effects. In this review, we summarize clinical trials, studies on human cells, and animal models, that provide a vast array of data in support of repurposing this class of antidiabetic drugs.
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Affiliation(s)
- Donato Cappetta
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Antonella De Angelis
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Gabriella Bellocchio
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Marialucia Telesca
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Eleonora Cianflone
- Department of Medical and Surgical Sciences, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Daniele Torella
- Department of Experimental and Clinical Medicine, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Francesco Rossi
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Konrad Urbanek
- Department of Experimental and Clinical Medicine, University "Magna Graecia" of Catanzaro, Catanzaro, Italy
| | - Liberato Berrino
- Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
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21
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Abstract
PURPOSE OF REVIEW This review offers a critical narrative evaluation of emerging evidence that sodium-glucose co-transporter-2 (SGLT2) inhibitors exert nephroprotective effects in people with type 2 diabetes. RECENT FINDINGS The SGLT2 inhibitor class of glucose-lowering agents has recently shown beneficial effects to reduce the onset and progression of renal complications in people with and without diabetes. Randomised clinical trials and 'real world' observational studies, mostly involving type 2 diabetes patients, have noted that use of an SGLT2 inhibitor can slow the decline in glomerular filtration rate (GFR), reduce the onset of microalbuminuria and slow or reverse the progression of proteinuria. The nephroprotective effects of SGLT2 inhibitors are class effects observed with each of the approved agents in people with a normal or impaired GFR. These effects are also observed in non-diabetic, lean and normotensive individuals suggesting that the mechanisms extend beyond the glucose-lowering, weight-lowering and blood pressure-lowering effects that accompany their glucosuric action in diabetes patients. A key mechanism is tubuloglomerular feedback in which SGLT2 inhibitors cause more sodium to pass along the nephron: the sodium is sensed by macula cells which act via adenosine to constrict afferent glomerular arterioles, thereby protecting glomeruli by reducing intraglomerular pressure. Other effects of SGLT2 inhibitors improve tubular oxygenation and metabolism and reduce renal inflammation and fibrosis. SGLT2 inhibitors have not increased the risk of urinary tract infections or the risk of acute kidney injury. However, introduction of an SGLT2 inhibitor in patients with a very low GFR is not encouraged due to an initial dip in GFR, and it is prudent to discontinue therapy if there is an acute renal event, hypovolaemia or hypotension.
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Affiliation(s)
| | - Caroline Day
- Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
| | - Srikanth Bellary
- Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
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22
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Vallon V, Nakagawa T. Renal Tubular Handling of Glucose and Fructose in Health and Disease. Compr Physiol 2021; 12:2995-3044. [PMID: 34964123 PMCID: PMC9832976 DOI: 10.1002/cphy.c210030] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The proximal tubule of the kidney is programmed to reabsorb all filtered glucose and fructose. Glucose is taken up by apical sodium-glucose cotransporters SGLT2 and SGLT1 whereas SGLT5 and potentially SGLT4 and GLUT5 have been implicated in apical fructose uptake. The glucose taken up by the proximal tubule is typically not metabolized but leaves via the basolateral facilitative glucose transporter GLUT2 and is returned to the systemic circulation or used as an energy source by distal tubular segments after basolateral uptake via GLUT1. The proximal tubule generates new glucose in metabolic acidosis and the postabsorptive phase, and fructose serves as an important substrate. In fact, under physiological conditions and intake, fructose taken up by proximal tubules is primarily utilized for gluconeogenesis. In the diabetic kidney, glucose is retained and gluconeogenesis enhanced, the latter in part driven by fructose. This is maladaptive as it sustains hyperglycemia. Moreover, renal glucose retention is coupled to sodium retention through SGLT2 and SGLT1, which induces secondary deleterious effects. SGLT2 inhibitors are new anti-hyperglycemic drugs that can protect the kidneys and heart from failing independent of kidney function and diabetes. Dietary excess of fructose also induces tubular injury. This can be magnified by kidney formation of fructose under pathological conditions. Fructose metabolism is linked to urate formation, which partially accounts for fructose-induced tubular injury, inflammation, and hemodynamic alterations. Fructose metabolism favors glycolysis over mitochondrial respiration as urate suppresses aconitase in the tricarboxylic acid cycle, and has been linked to potentially detrimental aerobic glycolysis (Warburg effect). © 2022 American Physiological Society. Compr Physiol 12:2995-3044, 2022.
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Affiliation(s)
- Volker Vallon
- Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, La Jolla, California, USA,Department of Pharmacology, University of California San Diego, La Jolla, California, USA,VA San Diego Healthcare System, San Diego, California, USA,Correspondence to and
| | - Takahiko Nakagawa
- Division of Nephrology, Rakuwakai-Otowa Hospital, Kyoto, Japan,Correspondence to and
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23
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Ansermet C, Centeno G, Bignon Y, Ortiz D, Pradervand S, Garcia A, Menin L, Gachon F, Yoshihara HA, Firsov D. Dysfunction of the circadian clock in the kidney tubule leads to enhanced kidney gluconeogenesis and exacerbated hyperglycemia in diabetes. Kidney Int 2021; 101:563-573. [PMID: 34838539 DOI: 10.1016/j.kint.2021.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 11/01/2021] [Accepted: 11/09/2021] [Indexed: 11/16/2022]
Abstract
The circadian clock is a ubiquitous molecular time-keeping mechanism which synchronizes cellular, tissue, and systemic biological functions with 24-hour environmental cycles. Local circadian clocks drive cell type- and tissue-specific rhythms and their dysregulation has been implicated in pathogenesis and/or progression of a broad spectrum of diseases. However, the pathophysiological role of intrinsic circadian clocks in the kidney of diabetics remains unknown. To address this question, we induced type I diabetes with streptozotocin in mice devoid of the circadian transcriptional regulator BMAL1 in podocytes (cKOp mice) or in the kidney tubule (cKOt mice). There was no association between dysfunction of the circadian clock and the development of diabetic nephropathy in cKOp and cKOt mice with diabetes. However, cKOt mice with diabetes exhibited exacerbated hyperglycemia, increased fractional excretion of glucose in the urine, enhanced polyuria, and a more pronounced kidney hypertrophy compared to streptozotocin-treated control mice. mRNA and protein expression analyses revealed substantial enhancement of the gluconeogenic pathway in kidneys of cKOt mice with diabetes as compared to diabetic control mice. Transcriptomic analysis along with functional analysis of cKOt mice with diabetes identified changes in multiple mechanisms directly or indirectly affecting the gluconeogenic pathway. Thus, we demonstrate that dysfunction of the intrinsic kidney tubule circadian clock can aggravate diabetic hyperglycemia via enhancement of gluconeogenesis in the kidney proximal tubule and further highlight the importance of circadian behavior in patients with diabetes.
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Affiliation(s)
- Camille Ansermet
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Gabriel Centeno
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Yohan Bignon
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Daniel Ortiz
- Mass Spectrometry Service, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Sylvain Pradervand
- Genomic Technologies Facility, University of Lausanne, Lausanne, Switzerland
| | - Andy Garcia
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Laure Menin
- Mass Spectrometry Service, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Frédéric Gachon
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland; Institute for Molecular Bioscience, The University of Queensland, Queensland, Australia
| | - Hikari Ai Yoshihara
- Institute of Physics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
| | - Dmitri Firsov
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.
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24
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Miyata KN, Lo CS, Zhao S, Zhao XP, Chenier I, Yamashita M, Filep JG, Ingelfinger JR, Zhang SL, Chan JSD. Deletion of heterogeneous nuclear ribonucleoprotein F in renal tubules downregulates SGLT2 expression and attenuates hyperfiltration and kidney injury in a mouse model of diabetes. Diabetologia 2021; 64:2589-2601. [PMID: 34370045 PMCID: PMC8992778 DOI: 10.1007/s00125-021-05538-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/26/2021] [Indexed: 10/20/2022]
Abstract
AIMS/HYPOTHESIS We previously reported that renal tubule-specific deletion of heterogeneous nuclear ribonucleoprotein F (Hnrnpf) results in upregulation of renal angiotensinogen (Agt) and downregulation of sodium-glucose co-transporter 2 (Sglt2) in HnrnpfRT knockout (KO) mice. Non-diabetic HnrnpfRT KO mice develop hypertension, renal interstitial fibrosis and glycosuria with no renoprotective effect from downregulated Sglt2 expression. Here, we investigated the effect of renal tubular Hnrnpf deletion on hyperfiltration and kidney injury in Akita mice, a model of type 1 diabetes. METHODS Akita HnrnpfRT KO mice were generated through crossbreeding tubule-specific (Pax8)-Cre mice with Akita floxed-Hnrnpf mice on a C57BL/6 background. Male non-diabetic control (Ctrl), Akita, and Akita HnrnpfRT KO mice were studied up to the age of 24 weeks (n = 8/group). RESULTS Akita mice exhibited elevated systolic blood pressure as compared with Ctrl mice, which was significantly higher in Akita HnrnpfRT KO mice than Akita mice. Compared with Akita mice, Akita HnrnpfRT KO mice had lower blood glucose levels with increased urinary glucose excretion. Akita mice developed kidney hypertrophy, glomerular hyperfiltration (increased glomerular filtration rate), glomerulomegaly, mesangial expansion, podocyte foot process effacement, thickened glomerular basement membranes, renal interstitial fibrosis and increased albuminuria. These abnormalities were attenuated in Akita HnrnpfRT KO mice. Treatment of Akita HnrnpfRT KO mice with a selective A1 adenosine receptor inhibitor resulted in an increase in glomerular filtration rate. Renal Agt expression was elevated in Akita mice and further increased in Akita HnrnpfRT KO mice. In contrast, Sglt2 expression was increased in Akita and decreased in Akita HnrnpfRT KO mice. CONCLUSIONS/INTERPRETATION The renoprotective effect of Sglt2 downregulation overcomes the renal injurious effect of Agt when these opposing factors coexist under diabetic conditions, at least partly via the activation of tubuloglomerular feedback.
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Affiliation(s)
- Kana N Miyata
- Département de Médecine, Université de Montréal, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
- Division of Nephrology, Department of Internal Medicine, Saint Louis University, St. Louis, MO, USA
| | - Chao-Sheng Lo
- Département de Médecine, Université de Montréal, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Shuiling Zhao
- Département de Médecine, Université de Montréal, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Xin-Ping Zhao
- Département de Médecine, Université de Montréal, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Isabelle Chenier
- Département de Médecine, Université de Montréal, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Michifumi Yamashita
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Janos G Filep
- Université de Montréal, Centre de recherche de l'Hopital Maisonneuve-Rosemont, Montréal, QC, Canada
| | - Julie R Ingelfinger
- Harvard Medical School, Pediatric Nephrology Unit, Massachusetts General Hospital, Boston, MA, USA
| | - Shao-Ling Zhang
- Département de Médecine, Université de Montréal, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada.
| | - John S D Chan
- Département de Médecine, Université de Montréal, Centre de recherche du Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada.
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25
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Ahmad AA, Draves SO, Rosca M. Mitochondria in Diabetic Kidney Disease. Cells 2021; 10:cells10112945. [PMID: 34831168 PMCID: PMC8616075 DOI: 10.3390/cells10112945] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 10/26/2021] [Accepted: 10/28/2021] [Indexed: 12/11/2022] Open
Abstract
Diabetic kidney disease (DKD) is the leading cause of end stage renal disease (ESRD) in the USA. The pathogenesis of DKD is multifactorial and involves activation of multiple signaling pathways with merging outcomes including thickening of the basement membrane, podocyte loss, mesangial expansion, tubular atrophy, and interstitial inflammation and fibrosis. The glomerulo-tubular balance and tubule-glomerular feedback support an increased glomerular filtration and tubular reabsorption, with the latter relying heavily on ATP and increasing the energy demand. There is evidence that alterations in mitochondrial bioenergetics in kidney cells lead to these pathologic changes and contribute to the progression of DKD towards ESRD. This review will focus on the dialogue between alterations in bioenergetics in glomerular and tubular cells and its role in the development of DKD. Alterations in energy substrate selection, electron transport chain, ATP generation, oxidative stress, redox status, protein posttranslational modifications, mitochondrial dynamics, and quality control will be discussed. Understanding the role of bioenergetics in the progression of diabetic DKD may provide novel therapeutic approaches to delay its progression to ESRD.
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26
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Ravindran S, Munusamy S. Renoprotective mechanisms of sodium-glucose co-transporter 2 (SGLT2) inhibitors against the progression of diabetic kidney disease. J Cell Physiol 2021; 237:1182-1205. [PMID: 34713897 DOI: 10.1002/jcp.30621] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/02/2021] [Accepted: 10/08/2021] [Indexed: 12/19/2022]
Abstract
Sodium-glucose co-transporter 2 inhibitors (SGLT2-Is) have emerged as a promising class of antidiabetic drugs with cardioprotective and renoprotective effects in patients with type 2 diabetes (T2D). The sodium-glucose co-transporters 1 and 2 (SGLT 1 and SGLT2) located in the renal proximal tubules are responsible for glucose reabsorption from the glomerular filtrate back into the systemic circulation. Inhibition of SGLT2, which accounts for about 90% of the glucose reabsorption, leads to a significant reduction in blood glucose levels and a concomitant increase in the urinary excretion of glucose (glycosuria). Multiple mechanisms contribute to the nephroprotective effects of SGLT2-Is in T2D patients. These include: (1) Restoration of the tubuloglomerular feedback by increasing sodium delivery at macula densa, leading to afferent arteriolar constriction and reduced glomerular hyperfiltration, (2) Decreased activation of the intra-renal renin-angiotensin-aldosterone system, which also contributes to reducing glomerular hyperfiltration, (3) Increased production of ketone bodies, which serves as an alternate fuel for adenosine triphosphate production in mitochondria, which helps in attenuating inflammation, and (4) Protection against hypoxia, oxidative stress, and fibrosis. This review elaborates on the key mechanisms that underlie the nephroprotective effects and the adverse effects of SGLT2-Is in T2D patients with progressive diabetic kidney disease.
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Affiliation(s)
| | - Shankar Munusamy
- Department of Pharmaceutical and Administrative Sciences, Drake University College of Pharmacy and Health Sciences, Des Moines, Iowa, USA
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27
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Packer M. Differential Pathophysiological Mechanisms in Heart Failure With a Reduced or Preserved Ejection Fraction in Diabetes. JACC-HEART FAILURE 2021; 9:535-549. [PMID: 34325884 DOI: 10.1016/j.jchf.2021.05.019] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 05/17/2021] [Accepted: 05/27/2021] [Indexed: 12/11/2022]
Abstract
Diabetes promotes the development of both heart failure with a reduced ejection fraction and heart failure with a preserved ejection fraction through diverse mechanisms, which are likely mediated through hyperinsulinemia rather than hyperglycemia. Diabetes promotes nutrient surplus signaling (through Akt and mammalian target of rapamycin complex 1) and inhibits nutrient deprivation signaling (through sirtuin-1 and its downstream effectors); this suppresses autophagy and promotes endoplasmic reticulum and oxidative stress and mitochondrial dysfunction, thereby undermining the health of diabetic cardiomyocytes. The hyperinsulinemia of diabetes may also activate sodium-hydrogen exchangers in cardiomyocytes (leading to injury and loss) and in the proximal renal tubules (leading to sodium retention). Diabetes may cause epicardial adipose tissue expansion, and the resulting secretion of proinflammatory adipocytokines onto the adjoining myocardium can lead to coronary microcirculatory dysfunction and myocardial inflammation and fibrosis. Interestingly, sodium-glucose cotransporter 2 (SGLT2) inhibitors-the only class of antidiabetic medication that reduces serious heart failure events-may act to mitigate each of these mechanisms. SGLT2 inhibitors up-regulate sirtuin-1 and its downstream effectors and autophagic flux, thus explaining the actions of these drugs to reduce oxidative stress, normalize mitochondrial structure and function, and mute proinflammatory pathways in the stressed myocardium. Inhibition of SGLT2 may also lead to a reduction in the activity of sodium-hydrogen exchangers in the kidney (leading to diuresis) and in the heart (attenuating the development of cardiac hypertrophy and systolic dysfunction). Finally, SGLT2 inhibitors reduce the mass and mute the adverse biology of epicardial adipose tissue (and reduce the secretion of leptin), thus explaining the capacity of these drugs to mitigate myocardial inflammation, microcirculatory dysfunction, and fibrosis, and improve ventricular filling dynamics. The pathophysiological mechanisms by which SGLT2 inhibitors may benefit heart failure likely differ depending on ejection fraction, but each represents interference with distinct pathways by which hyperinsulinemia may adversely affect cardiac structure and function.
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Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute, Baylor University Medical Center, Dallas, Texas, USA; Imperial College, London, United Kingdom.
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28
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Liu J, Tian J, Sodhi K, Shapiro JI. The Na/K-ATPase Signaling and SGLT2 Inhibitor-Mediated Cardiorenal Protection: A Crossed Road? J Membr Biol 2021; 254:513-529. [PMID: 34297135 PMCID: PMC8595165 DOI: 10.1007/s00232-021-00192-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/06/2021] [Indexed: 12/17/2022]
Abstract
In different large-scale clinic outcome trials, sodium (Na+)/glucose co-transporter 2 (SGLT2) inhibitors showed profound cardiac- and renal-protective effects, making them revolutionary treatments for heart failure and kidney disease. Different theories are proposed according to the emerging protective effects other than the original purpose of glucose-lowering in diabetic patients. As the ATP-dependent primary ion transporter providing the Na+ gradient to drive other Na+-dependent transporters, the possible role of the sodium–potassium adenosine triphosphatase (Na/K-ATPase) as the primary ion transporter and its signaling function is not explored.
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Affiliation(s)
- Jiang Liu
- Department of Biomedical Sciences, JCE School of Medicine, Marshall University, Huntington, WV, USA.
| | - Jiang Tian
- Department of Biomedical Sciences, JCE School of Medicine, Marshall University, Huntington, WV, USA
| | - Komal Sodhi
- Department of Surgery, JCE School of Medicine, Marshall University, Huntington, WV, USA
| | - Joseph I Shapiro
- Departments of Medicine, JCE School of Medicine, Marshall University, Huntington, WV, USA
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29
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Pathophysiology of diabetic kidney disease: impact of SGLT2 inhibitors. Nat Rev Nephrol 2021; 17:319-334. [PMID: 33547417 DOI: 10.1038/s41581-021-00393-8] [Citation(s) in RCA: 243] [Impact Index Per Article: 81.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2021] [Indexed: 01/30/2023]
Abstract
Diabetic kidney disease is the leading cause of kidney failure worldwide; in the USA, it accounts for over 50% of individuals entering dialysis or transplant programmes. Unlike other complications of diabetes, the prevalence of diabetic kidney disease has failed to decline over the past 30 years. Hyperglycaemia is the primary aetiological factor responsible for the development of diabetic kidney disease. Once hyperglycaemia becomes established, multiple pathophysiological disturbances, including hypertension, altered tubuloglomerular feedback, renal hypoxia, lipotoxicity, podocyte injury, inflammation, mitochondrial dysfunction, impaired autophagy and increased activity of the sodium-hydrogen exchanger, contribute to progressive glomerular sclerosis and the decline in glomerular filtration rate. The quantitative contribution of each of these abnormalities to the progression of diabetic kidney disease, as well as their role in type 1 and type 2 diabetes mellitus, remains to be determined. Sodium-glucose co-transporter 2 (SGLT2) inhibitors have a beneficial impact on many of these pathophysiological abnormalities; however, as several pathophysiological disturbances contribute to the onset and progression of diabetic kidney disease, multiple agents used in combination will likely be required to slow the progression of disease effectively.
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30
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Thomson SC, Vallon V. Effects of SGLT2 inhibitor and dietary NaCl on glomerular hemodynamics assessed by micropuncture in diabetic rats. Am J Physiol Renal Physiol 2021; 320:F761-F771. [PMID: 33645318 PMCID: PMC8174804 DOI: 10.1152/ajprenal.00552.2020] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 02/09/2021] [Accepted: 02/19/2021] [Indexed: 01/10/2023] Open
Abstract
Inhibitors of the main proximal tubular Na-glucose cotransporter (SGLT2) mitigate diabetic glomerular hyperfiltration and have been approved by the United States Food and Drug Administration for slowing the progression of diabetic kidney disease. It has been proposed that SGLT2 inhibitors improve hard renal outcomes by reducing glomerular capillary pressure (PGC) via a tubuloglomerular feedback (TGF) response to a decrease in proximal reabsorption (Jprox). However, the effect of SGLT2 inhibition on PGC has not been measured. Here, we studied the effects of acute SGLT2 blockade (ertugliflozin) on Jprox and glomerular hemodynamics in two-period micropuncture experiments using streptozotocin-induced diabetic rats fed high- or low-NaCl diets. PGC was measured by direct capillary puncture or computed from tubular stop-flow pressure (PSF). TGF is intact while measuring PGC directly but rendered inoperative when measuring PSF. Acute SGLT2 inhibitor reduced Jprox by ∼30%, reduced PGC by 5-8 mmHg, and reduced glomerular filtration rate (GFR) by ∼25% (all P < 0.0001) but had no effect on PSF. The decrease in PGC was larger with the low-NaCl diet (8 vs. 5 mmHg, P = 0.04) where PGC was higher to begin with (54 vs. 50 mmHg, P = 0.003). Greater decreases in PGC corresponded, unexpectedly, to lesser decreases in GFR (P = 0.04). In conclusion, these results confirm expectations that PGC would decline in response to acute SGLT2 inhibition and that a functioning TGF system is required for this. We infer a contribution of postglomerular vasorelaxation to the TGF responses where decreases in PGC were large and decreases in GFR were small.NEW & NOTEWORTHY It has been theorized that Na-glucose cotransporter (SGLT2) blockade slows progression of diabetic kidney disease by reducing physical strain on the glomerulus. This is the first direct measurement of intraglomerular pressure during SGLT2 blockade. Findings confirmed that SGLT2 blockade does reduce glomerular capillary pressure, that this is mediated through tubuloglomerular feedback, and that the tubuloglomerular feedback response to SGLT2 blockade involves preglomerular vasoconstriction and postglomerular vasorelaxation.
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Affiliation(s)
- Scott Culver Thomson
- Division of Nephrology-Hypertension, Department of Medicine, University of California, San Diego, California; and Veterans Affairs San Diego Healthcare System, La Jolla, California
| | - Volker Vallon
- Division of Nephrology-Hypertension, Department of Medicine, University of California, San Diego, California; and Veterans Affairs San Diego Healthcare System, La Jolla, California
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31
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Bletsa E, Filippas-Dekouan S, Kostara C, Dafopoulos P, Dimou A, Pappa E, Chasapi S, Spyroulias G, Koutsovasilis A, Bairaktari E, Ferrannini E, Tsimihodimos V. Effect of Dapagliflozin on Urine Metabolome in Patients with Type 2 Diabetes. J Clin Endocrinol Metab 2021; 106:1269-1283. [PMID: 33592103 PMCID: PMC8063232 DOI: 10.1210/clinem/dgab086] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Indexed: 01/01/2023]
Abstract
CONTEXT Inhibitors of sodium-glucose cotransporters-2 have cardio- and renoprotective properties. However, the underlying mechanisms remain indeterminate. OBJECTIVE To evaluate the effect of dapagliflozin on renal metabolism assessed by urine metabolome analysis in patients with type 2 diabetes. DESIGN Prospective cohort study. SETTING Outpatient diabetes clinic of a tertiary academic center. PATIENTS Eighty patients with hemoglobin A1c > 7% on metformin monotherapy were prospectively enrolled. INTERVENTION Fifty patients were treated with dapagliflozin for 3 months. To exclude that the changes observed in urine metabolome were merely the result of the improvement in glycemia, 30 patients treated with insulin degludec were used for comparison. MAIN OUTCOME MEASURE Changes in urine metabolic profile before and after the administration of dapagliflozin and insulin degludec were assessed by proton-nuclear magnetic resonance spectroscopy. RESULTS In multivariate analysis urine metabolome was significantly altered by dapagliflozin (R2X = 0.819, R2Y = 0.627, Q2Y = 0.362, and coefficient of variation analysis of variance, P < 0.001) but not insulin. After dapagliflozin, the urine concentrations of ketone bodies, lactate, branched chain amino acids (P < 0.001), betaine, myo-inositol (P < 0001), and N-methylhydantoin (P < 0.005) were significantly increased. Additionally, the urine levels of alanine, creatine, sarcosine, and citrate were also increased (P < 0001, P <0.0001, and P <0.0005, respectively) whereas anserine decreased (P < 0005). CONCLUSIONS Dapagliflozin significantly affects urine metabolome in patients with type 2 diabetes in a glucose lowering-independent way. Most of the observed changes can be considered beneficial and may contribute to the renoprotective properties of dapagliflozin.
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Affiliation(s)
- Evdoxia Bletsa
- Third Internal Medicine Department, General Hospital of Nikaia, Athens, Greece
| | | | - Christina Kostara
- Laboratory of Clinical Chemistry, University of Ioannina, Ioannina, Greece
| | | | - Aikaterini Dimou
- Laboratory of Clinical Chemistry, University of Ioannina, Ioannina, Greece
| | - Eleni Pappa
- Department of Internal Medicine, University of Ioannina, Ioannina, Greece
| | | | | | | | - Eleni Bairaktari
- Laboratory of Clinical Chemistry, University of Ioannina, Ioannina, Greece
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Sen T, Heerspink HJL. A kidney perspective on the mechanism of action of sodium glucose co-transporter 2 inhibitors. Cell Metab 2021; 33:732-739. [PMID: 33691091 DOI: 10.1016/j.cmet.2021.02.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/25/2020] [Accepted: 02/17/2021] [Indexed: 02/07/2023]
Abstract
Sodium glucose co-transporter (SGLT) 2 inhibitors reduce the risk of kidney failure in patients with and without type 2 diabetes (T2D). Although the precise underlying mechanisms for these nephroprotective effects are incompletely understood, various hypotheses have been proposed including reductions in intraglomerular pressure through restoration of tubuloglomerular feedback, blood pressure reduction and favorable effects on vascular function, reduction in tubular workload and hypoxia, and metabolic effects resulting in increased autophagy. Here, we review these mechanisms, which may also explain the beneficial effects of SGLT2 inhibitors on kidney function in patients without T2D.
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Affiliation(s)
- Taha Sen
- Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Hiddo J L Heerspink
- Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; The George Institute for Global Health, Sydney, Australia.
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Abstract
SGLT2 inhibitors are antihyperglycemic drugs that protect kidneys and the heart of patients with or without type 2 diabetes and preserved or reduced kidney function from failing. The involved protective mechanisms include blood glucose-dependent and -independent mechanisms: SGLT2 inhibitors prevent both hyper- and hypoglycemia, with expectedly little net effect on HbA1C. Metabolic adaptations to induced urinary glucose loss include reduced fat mass and more ketone bodies as additional fuel. SGLT2 inhibitors lower glomerular capillary hypertension and hyperfiltration, thereby reducing the physical stress on the filtration barrier, albuminuria, and the oxygen demand for tubular reabsorption. This improves cortical oxygenation, which, together with lesser tubular gluco-toxicity, may preserve tubular function and glomerular filtration rate in the long term. SGLT2 inhibitors may mimic systemic hypoxia and stimulate erythropoiesis, which improves organ oxygen delivery. SGLT2 inhibitors are proximal tubule and osmotic diuretics that reduce volume retention and blood pressure and preserve heart function, potentially in part by overcoming the resistance to diuretics and atrial-natriuretic-peptide and inhibiting Na-H exchangers and sympathetic tone.
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Affiliation(s)
- Volker Vallon
- Division of Nephrology and Hypertension, Department of Medicine, University of California, San Diego, La Jolla, California 92093, USA;
- Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, USA
- VA San Diego Healthcare System, San Diego, California 92161, USA
| | - Subodh Verma
- Division of Cardiac Surgery, St. Michael's Hospital, University of Toronto, Toronto, Ontario M5B 1W8, Canada;
- Departments of Surgery and Pharmacology and Toxicology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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Duan S, Lu F, Song D, Zhang C, Zhang B, Xing C, Yuan Y. Current Challenges and Future Perspectives of Renal Tubular Dysfunction in Diabetic Kidney Disease. Front Endocrinol (Lausanne) 2021; 12:661185. [PMID: 34177803 PMCID: PMC8223745 DOI: 10.3389/fendo.2021.661185] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/21/2021] [Indexed: 12/29/2022] Open
Abstract
Over decades, substantial progress has been achieved in understanding the pathogenesis of proteinuria in diabetic kidney disease (DKD), biomarkers for DKD screening, diagnosis, and prognosis, as well as novel hypoglycemia agents in clinical trials, thereby rendering more attention focused on the role of renal tubules in DKD. Previous studies have demonstrated that morphological and functional changes in renal tubules are highly involved in the occurrence and development of DKD. Novel tubular biomarkers have shown some clinical importance. However, there are many challenges to transition into personalized diagnosis and guidance for individual therapy in clinical practice. Large-scale clinical trials suggested the clinical relevance of increased proximal reabsorption and hyperfiltration by sodium-glucose cotransporter-2 (SGLT2) to improve renal outcomes in patients with diabetes, further promoting the emergence of renal tubulocentric research. Therefore, this review summarized the recent progress in the pathophysiology associated with involved mechanisms of renal tubules, potential tubular biomarkers with clinical application, and renal tubular factors in DKD management. The mechanism of kidney protection and impressive results from clinical trials of SGLT2 inhibitors were summarized and discussed, offering a comprehensive update on therapeutic strategies targeting renal tubules.
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Molecular Mechanisms of SGLT2 Inhibitor on Cardiorenal Protection. Int J Mol Sci 2020; 21:ijms21217833. [PMID: 33105763 PMCID: PMC7660105 DOI: 10.3390/ijms21217833] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/20/2020] [Accepted: 10/20/2020] [Indexed: 12/14/2022] Open
Abstract
The development of sodium-glucose transporter 2 inhibitor (SGLT2i) broadens the therapeutic strategies in treating diabetes mellitus. By inhibiting sodium and glucose reabsorption from the proximal tubules, the improvement in insulin resistance and natriuresis improved the cardiovascular mortality in diabetes mellitus (DM) patients. It has been known that SGLT2i also provided renoprotection by lowering the intraglomerular hypertension by modulating the pre- and post- glomerular vascular tone. The application of SGLT2i also provided metabolic and hemodynamic benefits in molecular aspects. The recent DAPA-CKD trial and EMPEROR-Reduced trial provided clinical evidence of renal and cardiac protection, even in non-DM patients. Therefore, the aim of the review is to clarify the hemodynamic and metabolic modulation of SGLT2i from the molecular mechanism.
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Onishi A, Fu Y, Patel R, Darshi M, Crespo-Masip M, Huang W, Song P, Freeman B, Kim YC, Soleimani M, Sharma K, Thomson SC, Vallon V. A role for tubular Na +/H + exchanger NHE3 in the natriuretic effect of the SGLT2 inhibitor empagliflozin. Am J Physiol Renal Physiol 2020; 319:F712-F728. [PMID: 32893663 DOI: 10.1152/ajprenal.00264.2020] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Inhibitors of proximal tubular Na+-glucose cotransporter 2 (SGLT2) are natriuretic, and they lower blood pressure. There are reports that the activities of SGLT2 and Na+-H+ exchanger 3 (NHE3) are coordinated. If so, then part of the natriuretic response to an SGLT2 inhibitor is mediated by suppressing NHE3. To examine this further, we compared the effects of an SGLT2 inhibitor, empagliflozin, on urine composition and systolic blood pressure (SBP) in nondiabetic mice with tubule-specific NHE3 knockdown (NHE3-ko) and wild-type (WT) littermates. A single dose of empagliflozin, titrated to cause minimal glucosuria, increased urinary excretion of Na+ and bicarbonate and raised urine pH in WT mice but not in NHE3-ko mice. Chronic empagliflozin treatment tended to lower SBP despite higher renal renin mRNA expression and lowered the ratio of SBP to renin mRNA, indicating volume loss. This effect of empagliflozin depended on tubular NHE3. In diabetic Akita mice, chronic empagliflozin enhanced phosphorylation of NHE3 (S552/S605), changes previously linked to lesser NHE3-mediated reabsorption. Chronic empagliflozin also increased expression of genes involved with renal gluconeogenesis, bicarbonate regeneration, and ammonium formation. While this could reflect compensatory responses to acidification of proximal tubular cells resulting from reduced NHE3 activity, these effects were at least in part independent of tubular NHE3 and potentially indicated metabolic adaptations to urinary glucose loss. Moreover, empagliflozin increased luminal α-ketoglutarate, which may serve to stimulate compensatory distal NaCl reabsorption, while cogenerated and excreted ammonium balances urine losses of this "potential bicarbonate." The data implicate NHE3 as a determinant of the natriuretic effect of empagliflozin.
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Affiliation(s)
- Akira Onishi
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Yiling Fu
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Rohit Patel
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Manjula Darshi
- Center for Renal Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Maria Crespo-Masip
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California.,Biomedical Research Institute, University of Lleida, Lleida, Spain
| | - Winnie Huang
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Panai Song
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Brent Freeman
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Young Chul Kim
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | | | - Kumar Sharma
- Center for Renal Precision Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Scott Culver Thomson
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Volker Vallon
- Department of Medicine, University of California-San Diego and Veterans Affairs San Diego Healthcare System, San Diego, California
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Gyimesi G, Pujol-Giménez J, Kanai Y, Hediger MA. Sodium-coupled glucose transport, the SLC5 family, and therapeutically relevant inhibitors: from molecular discovery to clinical application. Pflugers Arch 2020; 472:1177-1206. [PMID: 32767111 PMCID: PMC7462921 DOI: 10.1007/s00424-020-02433-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 06/24/2020] [Accepted: 07/02/2020] [Indexed: 02/06/2023]
Abstract
Sodium glucose transporters (SGLTs) belong to the mammalian solute carrier family SLC5. This family includes 12 different members in human that mediate the transport of sugars, vitamins, amino acids, or smaller organic ions such as choline. The SLC5 family belongs to the sodium symporter family (SSS), which encompasses transporters from all kingdoms of life. It furthermore shares similarity to the structural fold of the APC (amino acid-polyamine-organocation) transporter family. Three decades after the first molecular identification of the intestinal Na+-glucose cotransporter SGLT1 by expression cloning, many new discoveries have evolved, from mechanistic analysis to molecular genetics, structural biology, drug discovery, and clinical applications. All of these advances have greatly influenced physiology and medicine. While SGLT1 is essential for fast absorption of glucose and galactose in the intestine, the expression of SGLT2 is largely confined to the early part of the kidney proximal tubules, where it reabsorbs the bulk part of filtered glucose. SGLT2 has been successfully exploited by the pharmaceutical industry to develop effective new drugs for the treatment of diabetic patients. These SGLT2 inhibitors, termed gliflozins, also exhibit favorable nephroprotective effects and likely also cardioprotective effects. In addition, given the recent finding that SGLT2 is also expressed in tumors of pancreas and prostate and in glioblastoma, this opens the door to potential new therapeutic strategies for cancer treatment by specifically targeting SGLT2. Likewise, further discoveries related to the functional association of other SGLTs of the SLC5 family to human pathologies will open the door to potential new therapeutic strategies. We furthermore hope that the herein summarized information about the physiological roles of SGLTs and the therapeutic benefits of the gliflozins will be useful for our readers to better understand the molecular basis of the beneficial effects of these inhibitors, also in the context of the tubuloglomerular feedback (TGF), and the renin-angiotensin system (RAS). The detailed mechanisms underlying the clinical benefits of SGLT2 inhibition by gliflozins still warrant further investigation that may serve as a basis for future drug development.
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Affiliation(s)
- Gergely Gyimesi
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Office D845, Freiburgstrasse 15, CH-3010, Bern, Switzerland
| | - Jonai Pujol-Giménez
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Office D845, Freiburgstrasse 15, CH-3010, Bern, Switzerland
| | - Yoshikatsu Kanai
- Department of Bio-system Pharmacology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Matthias A Hediger
- Membrane Transport Discovery Lab, Department of Nephrology and Hypertension, and Department of Biomedical Research, Inselspital, University of Bern, Kinderklinik, Office D845, Freiburgstrasse 15, CH-3010, Bern, Switzerland.
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Vallon V. Glucose transporters in the kidney in health and disease. Pflugers Arch 2020; 472:1345-1370. [PMID: 32144488 PMCID: PMC7483786 DOI: 10.1007/s00424-020-02361-w] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 02/18/2020] [Accepted: 02/20/2020] [Indexed: 02/06/2023]
Abstract
The kidneys filter large amounts of glucose. To prevent the loss of this valuable fuel, the tubular system of the kidney, particularly the proximal tubule, has been programmed to reabsorb all filtered glucose. The machinery involves the sodium-glucose cotransporters SGLT2 and SGLT1 on the apical membrane and the facilitative glucose transporter GLUT2 on the basolateral membrane. The proximal tubule also generates new glucose, particularly in the post-absorptive phase but also to enhance bicarbonate formation and maintain acid-base balance. The glucose reabsorbed or formed by the proximal tubule is primarily taken up into peritubular capillaries and returned to the systemic circulation or provided as an energy source to further distal tubular segments that take up glucose by basolateral GLUT1. Recent studies provided insights on the coordination of renal glucose reabsorption, formation, and usage. Moreover, a better understanding of renal glucose transport in disease states is emerging. This includes the kidney in diabetes mellitus, when renal glucose retention becomes maladaptive and contributes to hyperglycemia. Furthermore, enhanced glucose reabsorption is coupled to sodium retention through the sodium-glucose cotransporter SGLT2, which induces secondary deleterious effects. As a consequence, SGLT2 inhibitors are new anti-hyperglycemic drugs that can protect the kidneys and heart from failing. Recent studies discovered unique roles for SGLT1 with implications in acute kidney injury and glucose sensing at the macula densa. This review discusses established and emerging concepts of renal glucose transport, and outlines the need for a better understanding of renal glucose handling in health and disease.
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Affiliation(s)
- Volker Vallon
- Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA, USA.
- Department of Pharmacology, University of California San Diego, La Jolla, CA, USA.
- VA San Diego Healthcare System, San Diego, CA, USA.
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An inducible intestinal epithelial cell-specific NHE3 knockout mouse model mimicking congenital sodium diarrhea. Clin Sci (Lond) 2020; 134:941-953. [PMID: 32227118 PMCID: PMC8819665 DOI: 10.1042/cs20200065] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/25/2020] [Accepted: 03/27/2020] [Indexed: 12/13/2022]
Abstract
The sodium–hydrogen exchanger isoform 3 (NHE3, SLC9A3) is abundantly expressed in the gastrointestinal tract and is proposed to play essential roles in Na+ and fluid absorption as well as acid–base homeostasis. Mutations in the SLC9A3 gene can cause congenital sodium diarrhea (CSD). However, understanding the precise role of intestinal NHE3 has been severely hampered due to the lack of a suitable animal model. To navigate this problem and better understand the role of intestinal NHE3, we generated a tamoxifen-inducible intestinal epithelial cell-specific NHE3 knockout mouse model (NHE3IEC-KO). Before tamoxifen administration, the phenotype and blood parameters of NHE3IEC-KO were unremarkable compared with control mice. After tamoxifen administration, NHE3IEC-KO mice have undetectable levels of NHE3 in the intestine. NHE3IEC-KO mice develop watery, alkaline diarrhea in combination with a swollen small intestine, cecum and colon. The persistent diarrhea results in higher fluid intake. After 3 weeks, NHE3IEC-KO mice show a ~25% mortality rate. The contribution of intestinal NHE3 to acid–base and Na+ homeostasis under normal conditions becomes evident in NHE3IEC-KO mice that have metabolic acidosis, lower blood bicarbonate levels, hyponatremia and hyperkalemia associated with drastically elevated plasma aldosterone levels. These results demonstrate that intestinal NHE3 has a significant contribution to acid–base, Na+ and volume homeostasis, and lack of intestinal NHE3 has consequences on intestinal structural integrity. This mouse model mimics and explains the phenotype of individuals with CSD carrying SLC9A3 mutations.
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Abstract
PURPOSE OF REVIEW SGLT2 inhibitors are a new class of antihyperglycemic drugs that protect kidneys and hearts of type 2 diabetic (T2DM) patients with preserved kidney function from failing. Here we discuss new insights on renal protection. RECENT FINDINGS Also in T2DM patients with CKD, SGLT2 inhibition causes an immediate functional reduction in glomerular filtration rate (GFR) and reduces blood pressure and preserves kidney and heart function in the long-term, despite a lesser antihyperglycemic effect. According to modeling studies, the GFR reduction reduces the tubular transport work and metabolic demand, thereby improving renal cortical oxygenation. In humans, the latter is linked to protection from CKD. Urine metabolomics in T2DM patients suggested improved renal mitochondrial function in response to SGLT2 inhibition, and experimental studies indicated improved tubular autophagy. Modeling studies predicted that also in diabetic CKD, SGLT2 inhibition is natriuretic and potentially stimulates erythropoiesis by mimicking systemic hypoxia in the kidney. Meta-analyses indicated that SGLT2 inhibition also reduces risk and severity of acute kidney injury in T2DM patients. Studies in nondiabetic mice implied inhibition of the renal urate transporter URAT1 in the uricosuric effect of SGLT2 inhibition. SUMMARY Renoprotection of SGLT2 inhibition involves blood glucose-dependent and independent effects and extends to CKD.
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Kim YC, Ganguly S, Nespoux J, Freeman B, Zhang H, Brenner D, Dhar D, Vallon V. Western Diet Promotes Renal Injury, Inflammation, and Fibrosis in a Murine Model of Alström Syndrome. Nephron Clin Pract 2020; 144:400-412. [PMID: 32629454 DOI: 10.1159/000508636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 05/12/2020] [Indexed: 12/26/2022] Open
Abstract
INTRODUCTION Alström syndrome is a rare recessive genetic disease caused by mutations in ALMS1, which encodes a protein that is related to cilia function and intracellular endosome trafficking. The syndrome has been linked to impaired glucose metabolism and CKD. Polymorphisms in Alms1 have likewise been linked to CKD, but little is known about the modification of the phenotype by environmental factors. METHODS To gain further insights, the fat aussie (foz) mouse strain, a genetic murine model of Alström syndrome, was exposed to a normal chow (NC) or to a Western diet (WD, 20% fat, 34% sucrose by weight, and 0.2% cholesterol) and renal outcomes were measured. RESULTS Body weight and albuminuria were higher in foz than in wild-type (WT) mice on both diets but WD significantly increased the difference. Measurement of plasma creatinine and cystatin C indicated that glomerular filtration rate was preserved in foz versus WT independent of diet. Renal markers of injury, inflammation, and fibrosis were similar in both genotypes on NC but significantly greater in foz than in WT mice on WD. A glucose tolerance test performed in foz and WT mice on WD revealed similar basal blood glucose levels and subsequent blood glucose profiles. CONCLUSIONS WD sensitizes a murine model of Alström syndrome to kidney injury, inflammation, and fibrosis, an effect that may not be solely due to effects on glucose metabolism. Polymorphisms in Alms1 may induce CKD in part by modulating the deleterious effects of high dietary fat and sucrose on kidney outcome.
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Affiliation(s)
- Young Chul Kim
- Division of Nephrology & Hypertension, Department of Medicine, University of California San Diego & VA San Diego Healthcare System, San Diego, California, USA
| | - Souradipta Ganguly
- Division of Gastroenterology, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Josselin Nespoux
- Division of Nephrology & Hypertension, Department of Medicine, University of California San Diego & VA San Diego Healthcare System, San Diego, California, USA
| | - Brent Freeman
- Division of Nephrology & Hypertension, Department of Medicine, University of California San Diego & VA San Diego Healthcare System, San Diego, California, USA
| | - Haiyan Zhang
- Division of Nephrology & Hypertension, Department of Medicine, University of California San Diego & VA San Diego Healthcare System, San Diego, California, USA
| | - David Brenner
- Division of Gastroenterology, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Debanjan Dhar
- Division of Gastroenterology, Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Volker Vallon
- Division of Nephrology & Hypertension, Department of Medicine, University of California San Diego & VA San Diego Healthcare System, San Diego, California, USA,
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Packer M. Interplay of adenosine monophosphate-activated protein kinase/sirtuin-1 activation and sodium influx inhibition mediates the renal benefits of sodium-glucose co-transporter-2 inhibitors in type 2 diabetes: A novel conceptual framework. Diabetes Obes Metab 2020; 22:734-742. [PMID: 31916329 DOI: 10.1111/dom.13961] [Citation(s) in RCA: 52] [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: 12/01/2019] [Revised: 12/29/2019] [Accepted: 01/04/2020] [Indexed: 12/11/2022]
Abstract
Long-term treatment with sodium-glucose co-transporter-2 (SGLT2) inhibitors slows the deterioration of renal function in patients with diabetes. This benefit cannot be ascribed to an action on blood glucose, ketone utilization, uric acid or systolic blood pressure. SGLT2 inhibitors produce a striking amelioration of glomerular hyperfiltration. Although initially ascribed to an action of these drugs to inhibit proximal tubular glucose reabsorption, SGLT2 inhibitors exert renoprotective effects, even in patients with meaningfully impaired levels of glomerular function that are sufficient to abolish their glycosuric actions. Instead, the reduction in intraglomerular pressures may be related to an action of SGLT2 inhibitors to interfere with the activity of sodium-hydrogen exchanger isoform 3, thereby inhibiting proximal tubular sodium reabsorption and promoting tubuloglomerular feedback. Yet, experimentally, such an effect may not be sufficient to prevent renal injury. It is therefore noteworthy that the diabetic kidney exhibits an important defect in adenosine monophosphate-activated protein kinase (AMPK) and sirtuin-1 (SIRT1) signalling, which may contribute to the development of nephropathy. These transcription factors exert direct effects to mute oxidative stress and inflammation, and they also stimulate autophagy, a lysosomally mediated degradative pathway that maintains cellular homeostasis in the kidney. SGLT2 inhibitors induce both AMPK and SIRT1, and they have been shown to stimulate autophagy, thereby ameliorating cellular stress and glomerular and tubular injury. Enhanced AMPK/SIRT1 signalling may also contribute to the action of SGLT2 inhibitors to interfere with sodium transport mechanisms. The dual effects of SGLT2 inhibitors on AMPK/SIRT1 activation and renal tubular sodium transport may explain the protective effects of these drugs on the kidney in type 2 diabetes.
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Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute, Baylor University Medical Center, Dallas, Texas
- Imperial College, London, UK
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Antihypertensive and Renal Mechanisms of SGLT2 (Sodium-Glucose Linked Transporter 2) Inhibitors. Hypertension 2020; 75:894-901. [DOI: 10.1161/hypertensionaha.119.11684] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Empaglifolzin, canagliflozin, and dapagliflozin are SGLT2 (sodium-glucose linked transporter type 2) inhibitors for treatment of type 2 diabetes mellitus that also reduce blood pressure, mortality, and cardiovascular disease and slow the loss of glomerular filtration rate. SGLT2 inhibitors inhibit the coupled reabsorption of sodium and glucose from the proximal tubules, thereby increasing renal glucose and sodium excretion, but they have more widespread renal effects, including inhibition of the sodium:proton exchanger. They increase the delivery of sodium to the loop of Henle and can thereby activate the tubuloglomerular feedback response to correct glomerular hyperfiltration. There are multiple potential mechanisms whereby these drugs lower blood pressure and preserve kidney function that are the focus of this review.
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Vallon V, Thomson SC. The tubular hypothesis of nephron filtration and diabetic kidney disease. Nat Rev Nephrol 2020; 16:317-336. [PMID: 32152499 DOI: 10.1038/s41581-020-0256-y] [Citation(s) in RCA: 219] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2020] [Indexed: 02/08/2023]
Abstract
Kidney size and glomerular filtration rate (GFR) often increase with the onset of diabetes, and elevated GFR is a risk factor for the development of diabetic kidney disease. Hyperfiltration mainly occurs in response to signals passed from the tubule to the glomerulus: high levels of glucose in the glomerular filtrate drive increased reabsorption of glucose and sodium by the sodium-glucose cotransporters SGLT2 and SGLT1 in the proximal tubule. Passive reabsorption of chloride and water also increases. The overall capacity for proximal reabsorption is augmented by growth of the proximal tubule, which (alongside sodium-glucose cotransport) further limits urinary glucose loss. Hyperreabsorption of sodium and chloride induces tubuloglomerular feedback from the macula densa to increase GFR. In addition, sodium-glucose cotransport by SGLT1 on macula densa cells triggers the production of nitric oxide, which also contributes to glomerular hyperfiltration. Although hyperfiltration restores sodium and chloride excretion it imposes added physical stress on the filtration barrier and increases the oxygen demand to drive reabsorption. Tubular growth is associated with the development of a senescence-like molecular signature that sets the stage for inflammation and fibrosis. SGLT2 inhibitors attenuate the proximal reabsorption of sodium and glucose, normalize tubuloglomerular feedback signals and mitigate hyperfiltration. This tubule-centred model of diabetic kidney physiology predicts the salutary effect of SGLT2 inhibitors on hard renal outcomes, as shown in large-scale clinical trials.
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Affiliation(s)
- Volker Vallon
- Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA, USA. .,Department of Pharmacology, University of California San Diego, La Jolla, CA, USA. .,VA San Diego Healthcare System, San Diego, CA, USA.
| | - Scott C Thomson
- Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA, USA.,VA San Diego Healthcare System, San Diego, CA, USA
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45
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Packer M. Autophagy stimulation and intracellular sodium reduction as mediators of the cardioprotective effect of sodium-glucose cotransporter 2 inhibitors. Eur J Heart Fail 2020; 22:618-628. [PMID: 32037659 DOI: 10.1002/ejhf.1732] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 11/26/2019] [Accepted: 11/28/2019] [Indexed: 12/17/2022] Open
Abstract
In five large-scale trials involving >40 000 patients, sodium-glucose cotransporter 2 (SGLT2) inhibitors decreased the risk of serious heart failure events by 25-40%. This effect cannot be explained by control of hyperglycaemia, since it is not observed with antidiabetic drugs with greater glucose-lowering effects. It cannot be attributed to ketogenesis, since it is not causally linked to ketone body production, and the benefit is not enhanced in patients with diabetes. The effect cannot be ascribed to a natriuretic action, since SGLT2 inhibitors decrease natriuretic peptides only modestly, and they reduce cardiovascular death, a benefit that diuretics do not possess. Although SGLT2 inhibitors increase red blood cell mass, enhanced erythropoiesis does not favourably influence the course of heart failure. By contrast, experimental studies suggest that SGLT2 inhibitors may reduce intracellular sodium, thereby preventing oxidative stress and cardiomyocyte death. Additionally, SGLT2 inhibitors induce a transcriptional paradigm that mimics nutrient and oxygen deprivation, which includes activation of adenosine monophosphate-activated protein kinase, sirtuin-1, and/or hypoxia-inducible factors-1α/2α. The interplay of these mediators stimulates autophagy, a lysosomally-mediated degradative pathway that maintains cellular homeostasis. Autophagy-mediated clearance of damaged organelles reduces inflammasome activation, thus mitigating cardiomyocyte dysfunction and coronary microvascular injury. Interestingly, the action of hypoxia-inducible factors-1α/2α to both stimulate erythropoietin and induce autophagy may explain why erythrocytosis is strongly correlated with the reduction in heart failure events. Therefore, the benefits of SGLT2 inhibitors on heart failure may be mediated by a direct cardioprotective action related to modulation of pathways responsible for cardiomyocyte homeostasis.
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Affiliation(s)
- Milton Packer
- Baylor Heart and Vascular Institute, Baylor University Medical Center, Dallas, TX, USA.,Imperial College, London, UK
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Masuda T, Muto S, Fukuda K, Watanabe M, Ohara K, Koepsell H, Vallon V, Nagata D. Osmotic diuresis by SGLT2 inhibition stimulates vasopressin-induced water reabsorption to maintain body fluid volume. Physiol Rep 2020; 8:e14360. [PMID: 31994353 PMCID: PMC6987478 DOI: 10.14814/phy2.14360] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 01/02/2020] [Accepted: 01/05/2020] [Indexed: 12/25/2022] Open
Abstract
Most of the filtered glucose is reabsorbed in the early proximal tubule by the sodium-glucose cotransporter SGLT2. The glycosuric effect of the SGLT2 inhibitor ipragliflozin is linked to a diuretic and natriuretic effect that activates compensatory increases in fluid and food intake to stabilize body fluid volume (BFV). However, the compensatory mechanisms that are activated on the level of renal tubules remain unclear. Type 2 diabetic Goto-Kakizaki (GK) rats were treated with vehicle or 0.01% (in diet) ipragliflozin with free access to fluid and food. After 8 weeks, GK rats were placed in metabolic cages for 24-hr. Ipragliflozin decreased body weight, serum glucose and systolic blood pressure, and increased fluid and food intake, urinary glucose and Na+ excretion, urine volume, and renal osmolar clearance, as well as urine vasopressin and solute-free water reabsorption (TcH2O). BFV, measured by bioimpedance spectroscopy, and fluid balance were similar among the two groups. Urine vasopressin in ipragliflozin-treated rats was negatively and positively associated with fluid balance and TcH2O, respectively. Ipragliflozin increased the renal membrane protein expression of SGLT2, aquaporin (AQP) 2 phosphorylated at Ser269 and vasopressin V2 receptor. The expression of SGLT1, GLUT2, AQP1, and AQP2 was similar between the groups. In conclusion, the SGLT2 inhibitor ipragliflozin induced a sustained glucosuria, diuresis, and natriuresis, with compensatory increases in fluid intake and vasopressin-induced TcH2O in proportion to the reduced fluid balance to maintain BFV. These results indicate that the osmotic diuresis induced by SGLT2 inhibition stimulates compensatory fluid intake and renal water reabsorption to maintain BFV.
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Affiliation(s)
- Takahiro Masuda
- Division of NephrologyDepartment of Internal MedicineJichi Medical UniversityShimotsukeTochigiJapan
| | - Shigeaki Muto
- Division of NephrologyDepartment of Internal MedicineJichi Medical UniversityShimotsukeTochigiJapan
| | - Keiko Fukuda
- Division of NephrologyDepartment of Internal MedicineJichi Medical UniversityShimotsukeTochigiJapan
| | - Minami Watanabe
- Division of NephrologyDepartment of Internal MedicineJichi Medical UniversityShimotsukeTochigiJapan
| | - Ken Ohara
- Division of NephrologyDepartment of Internal MedicineJichi Medical UniversityShimotsukeTochigiJapan
| | - Hermann Koepsell
- Department of Molecular Plant Physiology and BiophysicsJulius‐von‐Sachs‐Institute of BiosciencesUniversity of WürzburgWürzburgBavariaGermany
| | - Volker Vallon
- Division of Nephrology and HypertensionDepartment of Medicine and PharmacologyUniversity of California San Diego &VA San Diego Healthcare SystemSan DiegoCAUSA
| | - Daisuke Nagata
- Division of NephrologyDepartment of Internal MedicineJichi Medical UniversityShimotsukeTochigiJapan
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Thomson SC, Vallon V. Renal Effects of Sodium-Glucose Co-Transporter Inhibitors. Am J Cardiol 2019; 124 Suppl 1:S28-S35. [PMID: 31741437 DOI: 10.1016/j.amjcard.2019.10.027] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 08/06/2019] [Indexed: 12/28/2022]
Abstract
Sodium-glucose co-transporter 2 (SGLT2) inhibitors immediately reduce the glomerular filtration rate (GFR) in patients with type 2 diabetes mellitus. When given chronically, they confer benefit by markedly slowing the rate at which chronic kidney disease progresses and are the first agents to do so since the advent of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs). Salutary effects on the kidney were first demonstrated in cardiovascular outcomes trials and have now emerged from trials enriched in subjects with type 2 diabetes mellitus and chronic kidney disease. A simple model that unifies the immediate and long-term effects of SGLT2 inhibitors on kidney function is based on the assumption that diabetic hyperfiltration puts the kidney at long-term risk and evidence that hyperfiltration is an immediate response to a reduced signal for tubuloglomerular feedback, which occurs to the extent that SGLT2 activity mediates a primary increase in sodium and fluid reabsorption by the proximal tubule. This model will likely continue to serve as a useful description accounting for the beneficial effect of SGLT2 inhibitors on the diabetic kidney, similar to the hemodynamic explanation for the benefit of ACEIs and ARBs. A more complex model will be required to incorporate positive interactions between SGLT2 and sodium-hydrogen exchanger 3 in the proximal tubule and between sodium-glucose co-transporter 1 (SGLT1) and nitric oxide synthase in the macula densa. The implication of these latter nuances for day-to-day clinical medicine remains to be determined.
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