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Staltner R, Burger K, Baumann A, Bergheim I. Fructose: a modulator of intestinal barrier function and hepatic health? Eur J Nutr 2023; 62:3113-3124. [PMID: 37596353 PMCID: PMC10611622 DOI: 10.1007/s00394-023-03232-7] [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: 05/17/2023] [Accepted: 08/04/2023] [Indexed: 08/20/2023]
Abstract
PURPOSE Consumption of fructose has repeatedly been discussed to be a key factor in the development of health disturbances such as hypertension, diabetes type 2, and non-alcoholic fatty liver disease. Despite intense research efforts, the question if and how high dietary fructose intake interferes with human health has not yet been fully answered. RESULTS Studies suggest that besides its insulin-independent metabolism dietary fructose may also impact intestinal homeostasis and barrier function. Indeed, it has been suggested by the results of human and animal as well as in vitro studies that fructose enriched diets may alter intestinal microbiota composition. Furthermore, studies have also shown that both acute and chronic intake of fructose may lead to an increased formation of nitric oxide and a loss of tight junction proteins in small intestinal tissue. These alterations have been related to an increased translocation of pathogen-associated molecular patterns (PAMPs) like bacterial endotoxin and an induction of dependent signaling cascades in the liver but also other tissues. CONCLUSION In the present narrative review, results of studies assessing the effects of fructose on intestinal barrier function and their impact on the development of health disturbances with a particular focus on the liver are summarized and discussed.
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Affiliation(s)
- Raphaela Staltner
- Department of Nutritional Sciences, Molecular Nutritional Science, University of Vienna, Josef-Holaubek-Platz 2, A-1090, Vienna, Austria
| | - Katharina Burger
- Department of Nutritional Sciences, Molecular Nutritional Science, University of Vienna, Josef-Holaubek-Platz 2, A-1090, Vienna, Austria
| | - Anja Baumann
- Department of Nutritional Sciences, Molecular Nutritional Science, University of Vienna, Josef-Holaubek-Platz 2, A-1090, Vienna, Austria
| | - Ina Bergheim
- Department of Nutritional Sciences, Molecular Nutritional Science, University of Vienna, Josef-Holaubek-Platz 2, A-1090, Vienna, Austria.
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2
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Chen X, Hocher CF, Shen L, Krämer BK, Hocher B. Reno- and cardioprotective molecular mechanisms of SGLT2 inhibitors beyond glycemic control: from bedside to bench. Am J Physiol Cell Physiol 2023; 325:C661-C681. [PMID: 37519230 DOI: 10.1152/ajpcell.00177.2023] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 08/01/2023]
Abstract
Large placebo-controlled clinical trials have shown that sodium-glucose cotransporter-2 inhibitors (SGLT2i) delay the deterioration of renal function and reduce cardiovascular events in a glucose-independent manner, thereby ultimately reducing mortality in patients with chronic kidney disease (CKD) and/or heart failure. These existing clinical data stimulated preclinical studies aiming to understand the observed clinical effects. In animal models, it was shown that the beneficial effect of SGLT2i on the tubuloglomerular feedback (TGF) improves glomerular pressure and reduces tubular workload by improving renal hemodynamics, which appears to be dependent on salt intake. High salt intake might blunt the SGLT2i effects on the TGF. Beyond the salt-dependent effects of SGLT2i on renal hemodynamics, SGLT2i inhibited several key aspects of macrophage-mediated renal inflammation and fibrosis, including inhibiting the differentiation of monocytes to macrophages, promoting the polarization of macrophages from a proinflammatory M1 phenotype to an anti-inflammatory M2 phenotype, and suppressing the activation of inflammasomes and major proinflammatory factors. As macrophages are also important cells mediating atherosclerosis and myocardial remodeling after injury, the inhibitory effects of SGLT2i on macrophage differentiation and inflammatory responses may also play a role in stabilizing atherosclerotic plaques and ameliorating myocardial inflammation and fibrosis. Recent studies suggest that SGLT2i may also act directly on the Na+/H+ exchanger and Late-INa in cardiomyocytes thus reducing Na+ and Ca2+ overload-mediated myocardial damage. In addition, the renal-cardioprotective mechanisms of SGLT2i include systemic effects on the sympathetic nervous system, blood volume, salt excretion, and energy metabolism.
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Affiliation(s)
- Xin Chen
- Department of Nephrology, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology/Pneumology), University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Carl-Friedrich Hocher
- Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology/Pneumology), University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
- Klinik für Innere Medizin, Bundeswehrkrankenhaus Berlin, Berlin, Germany
| | - Linghong Shen
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Bernhard K Krämer
- Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology/Pneumology), University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
| | - Berthold Hocher
- Fifth Department of Medicine (Nephrology/Endocrinology/Rheumatology/Pneumology), University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany
- Reproductive and Genetic Hospital of CITIC-Xiangya, Changsha, China
- Institute of Reproductive and Stem Cell Engineering, NHC Key Laboratory of Human Stem Cell and Reproductive Engineering, School of Basic Medical Science, Central South University, Changsha, China
- IMD Institut für Medizinische Diagnostik Berlin-Potsdam GbR, Berlin, Germany
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3
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Suresh H, Mikhael M, Ho V, Zhou J. A HPLC-ESI-Q-ToF-MS Method for the Analysis of Monomer Constituents in PHGG, Gum Arabic And Psyllium Husk Prebiotic Dietary Fibre Supplements. INTERNATIONAL JOURNAL OF FOOD PROPERTIES 2022. [DOI: 10.1080/10942912.2022.2096064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Harsha Suresh
- School of Medicine, Western Sydney University, Campbelltown, Australia
- Gastrointestinal Motility Disorders Unit, Western Sydney University, Campbelltown, Australia
| | - Meena Mikhael
- School of Medicine, Western Sydney University, Campbelltown, Australia
- Mass Spectrometry Unit Research Services, Western Sydney University, Campbelltown, Australia
| | - Vincent Ho
- School of Medicine, Western Sydney University, Campbelltown, Australia
- Gastrointestinal Motility Disorders Unit, Western Sydney University, Campbelltown, Australia
- University Medical Clinic of Camden & Campbelltown (UMCCC), Campbelltown, Australia
| | - Jerry Zhou
- School of Medicine, Western Sydney University, Campbelltown, Australia
- Gastrointestinal Motility Disorders Unit, Western Sydney University, Campbelltown, Australia
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Tassopoulou VP, Tzara A, Kourounakis AP. Design of Improved Antidiabetic Drugs: A Journey from Single to Multitarget Agents. ChemMedChem 2022; 17:e202200320. [PMID: 36184571 DOI: 10.1002/cmdc.202200320] [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: 06/09/2022] [Revised: 09/27/2022] [Indexed: 01/14/2023]
Abstract
Multifactorial diseases exhibit a complex pathophysiology with several factors contributing to their pathogenesis and development. Examples of such disorders are neurodegenerative (e. g. Alzheimer's, Parkinson's) and cardiovascular diseases (e. g. atherosclerosis, metabolic syndrome, diabetes II). Traditional therapeutic approaches with single-target drugs have been proven, in many cases, unsatisfactory for the treatment of multifactorial diseases such as diabetes II. The well-established by now strategy of multitarget drugs is constantly gaining interest and momentum, as a more effective approach. The development of pharmacomolecules able to simultaneously modulate multiple relevant-to-the-disease targets has already several successful examples in various fields and has, as such, inspired the design of multitarget antidiabetic agents; this review highlights the design aspect and efficacy of this approach for improved antidiabetics by presenting several examples of successful pharmacophore combinations in (multitarget) agents that modulate two or more molecular targets involved in diabetes II, resulting in a superior antihyperglycemic profile.
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Affiliation(s)
- Vassiliki-Panagiota Tassopoulou
- Department of Medicinal Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, 15771, Athens, Greece
| | - Ariadni Tzara
- Department of Medicinal Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, 15771, Athens, Greece
| | - Angeliki P Kourounakis
- Department of Medicinal Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, 15771, Athens, Greece
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Theofilis P, Sagris M, Oikonomou E, Antonopoulos AS, Siasos G, Tsioufis K, Tousoulis D. The Anti-Inflammatory Effect of Novel Antidiabetic Agents. Life (Basel) 2022; 12:1829. [PMID: 36362984 PMCID: PMC9696750 DOI: 10.3390/life12111829] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 09/28/2022] [Accepted: 11/05/2022] [Indexed: 08/10/2023] Open
Abstract
The incidence of type 2 diabetes (T2DM) has been increasing worldwide and remains one of the leading causes of atherosclerotic disease. Several antidiabetic agents have been introduced in trying to regulate glucose control levels with different mechanisms of action. These agents, and sodium-glucose cotransporter-2 inhibitors in particular, have been endorsed by contemporary guidelines in patients with or without T2DM. Their widespread usage during the last three decades has raised awareness in the scientific community concerning their pleiotropic mechanisms of action, including their putative anti-inflammatory effect. In this review, we delve into the anti-inflammatory role and mechanism of the existing antidiabetic agents in the cardiovascular system and their potential use in other chronic sterile inflammatory conditions.
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Affiliation(s)
- Panagiotis Theofilis
- 1st Cardiology Department, “Hippokration” General Hospital, University of Athens Medical School, 11527 Athens, Greece
| | - Marios Sagris
- 3rd Cardiology Department, Thoracic Diseases Hospital “Sotiria”, University of Athens Medical School, 11527 Athens, Greece
| | - Evangelos Oikonomou
- 1st Cardiology Department, “Hippokration” General Hospital, University of Athens Medical School, 11527 Athens, Greece
- 3rd Cardiology Department, Thoracic Diseases Hospital “Sotiria”, University of Athens Medical School, 11527 Athens, Greece
| | - Alexios S. Antonopoulos
- 1st Cardiology Department, “Hippokration” General Hospital, University of Athens Medical School, 11527 Athens, Greece
| | - Gerasimos Siasos
- 1st Cardiology Department, “Hippokration” General Hospital, University of Athens Medical School, 11527 Athens, Greece
- 3rd Cardiology Department, Thoracic Diseases Hospital “Sotiria”, University of Athens Medical School, 11527 Athens, Greece
| | - Kostas Tsioufis
- 1st Cardiology Department, “Hippokration” General Hospital, University of Athens Medical School, 11527 Athens, Greece
| | - Dimitris Tousoulis
- 1st Cardiology Department, “Hippokration” General Hospital, University of Athens Medical School, 11527 Athens, Greece
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Tian L, Syed-Abdul MM, Stahel P, Lewis GF. Enteral glucose, absorbed and metabolized, potently enhances mesenteric lymph flow in chow- and high-fat-fed rats. Am J Physiol Gastrointest Liver Physiol 2022; 323:G331-G340. [PMID: 35916412 DOI: 10.1152/ajpgi.00095.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A portion of absorbed dietary triglycerides (TG) is retained in the intestine after the postprandial period, within intracellular and extracellular compartments. This pool of TG can be mobilized in response to several stimuli, including oral glucose. The objective of this study was to determine whether oral glucose must be absorbed and metabolized to mobilize TG in rats and whether high-fat feeding, a model of insulin resistance, alters the lipid mobilization response to glucose. Lymph flow, TG concentration, TG output, and apolipoprotein B48 (apoB48) concentration and output were assessed after an intraduodenal lipid bolus in rats exposed to the following intraduodenal administrations 5 h later: saline (placebo), glucose, 2-deoxyglucose (2-DG, absorbed but not metabolized), or glucose + phlorizin (intestinal glucose absorption inhibitor). Glucose alone, but not 2-DG or glucose + phlorizin treatments, stimulated lymph flow, TG output, and apoB48 output compared with placebo. The effects of glucose in high-fat-fed rats were similar to those in chow-fed rats. In conclusion, glucose must be both absorbed and metabolized to enhance lymph flow and intestinal lipid mobilization. This effect is qualitatively and quantitatively similar in high-fat- and chow-fed rats. The precise signaling mechanism whereby enteral glucose enhances lymph flow and mobilizes enteral lipid remains to be determined.NEW & NOTEWORTHY Glucose potently enhances mesenteric lymph flow in chow- and high-fat-fed rats. The magnitude of glucose effect on lymph flow is no different in chow- and high-fat-fed rats. Glucose must be absorbed and metabolized to enhance lymph flow and mobilize intestinal lipid.
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Affiliation(s)
- Lili Tian
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Majid Mufaqam Syed-Abdul
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Priska Stahel
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Gary F Lewis
- Division of Endocrinology, Department of Medicine and Banting & Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Holling T, Nampoothiri S, Tarhan B, Schneeberger PE, Vinayan KP, Yesodharan D, Roy AG, Radhakrishnan P, Alawi M, Rhodes L, Girisha KM, Kang PB, Kutsche K. Novel biallelic variants expand the SLC5A6-related phenotypic spectrum. Eur J Hum Genet 2022; 30:439-449. [PMID: 35013551 PMCID: PMC8747999 DOI: 10.1038/s41431-021-01033-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 12/09/2021] [Accepted: 12/17/2021] [Indexed: 11/09/2022] Open
Abstract
The sodium (Na+):multivitamin transporter (SMVT), encoded by SLC5A6, belongs to the sodium:solute symporter family and is required for the Na+-dependent uptake of biotin (vitamin B7), pantothenic acid (vitamin B5), the vitamin-like substance α-lipoic acid, and iodide. Compound heterozygous SLC5A6 variants have been reported in individuals with variable multisystemic disorder, including failure to thrive, developmental delay, seizures, cerebral palsy, brain atrophy, gastrointestinal problems, immunodeficiency, and/or osteopenia. We expand the phenotypic spectrum associated with biallelic SLC5A6 variants affecting function by reporting five individuals from three families with motor neuropathies. We identified the homozygous variant c.1285 A > G [p.(Ser429Gly)] in three affected siblings and a simplex patient and the maternally inherited c.280 C > T [p.(Arg94*)] variant and the paternally inherited c.485 A > G [p.(Tyr162Cys)] variant in the simplex patient of the third family. Both missense variants were predicted to affect function by in silico tools. 3D homology modeling of the human SMVT revealed 13 transmembrane helices (TMs) and Tyr162 and Ser429 to be located at the cytoplasmic facing region of TM4 and within TM11, respectively. The SLC5A6 missense variants p.(Tyr162Cys) and p.(Ser429Gly) did not affect plasma membrane localization of the ectopically expressed multivitamin transporter suggesting reduced but not abolished function, such as lower catalytic activity. Targeted therapeutic intervention yielded clinical improvement in four of the five patients. Early molecular diagnosis by exome sequencing is essential for timely replacement therapy in affected individuals.
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Affiliation(s)
- Tess Holling
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Sheela Nampoothiri
- Department of Pediatric Genetics, Amrita Institute of Medical Sciences & Research Centre, Cochin, 682041, Kerala, India
| | - Bedirhan Tarhan
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, 32610, USA
| | - Pauline E Schneeberger
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
- Amedes MVZ Wagnerstibbe für Laboratoriumsmedizin, Hämostaseologie, Humangenetik und Mikrobiologie Hannover, 30159, Hannover, Germany
| | | | - Dhanya Yesodharan
- Department of Pediatric Genetics, Amrita Institute of Medical Sciences & Research Centre, Cochin, 682041, Kerala, India
| | - Arun Grace Roy
- Department of Neurology, Amrita Institute of Medical Sciences & Research Centre, Cochin, 682041, Kerala, India
| | - Periyasamy Radhakrishnan
- Suma Genomics Pvt. Ltd, Manipal Universal Technology Business Incubator (MUTBI), Manipal, 576104, India
| | - Malik Alawi
- Bioinformatics Core, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | | | - Katta Mohan Girisha
- Department of Medical Genetics, Kasturba Medical College, Manipal, 576104, India
| | - Peter B Kang
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, 32610, USA.
- Paul and Sheila Wellstone Muscular Dystrophy Center, University of Minnesota Medical School, Minneapolis, MN, 55455, USA.
- Department of Neurology, University of Minnesota Medical School, Minneapolis, MN, 55455, USA.
- Institute for Translational Neuroscience, University of Minnesota Medical School, Minneapolis, MN, 55455, USA.
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany.
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8
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Alamoudi LO, Alfaraidi AT, Althagafi SS, Al-Thaqafy MS, Hasosah M. Congenital Glucose-Galactose Malabsorption: A Case With a Novel SLC5A1 Mutation in a Saudi Infant. Cureus 2021; 13:e18440. [PMID: 34737908 PMCID: PMC8559579 DOI: 10.7759/cureus.18440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/02/2021] [Indexed: 11/18/2022] Open
Abstract
While only a few hundred cases have been reported in pediatrics, congenital glucose-galactose malabsorption (GGM) is an extremely rare autosomal-recessive metabolic disorder that is characterized by intractable diarrhea and severe dehydration, which can be life-threatening if not treated appropriately. Due to the rarity of the disease, it is challenging to consider GGM as an initial diagnosis for most clinicians. We report the clinical and diagnostic course of a seven-month-old Saudi infant who presented with severe recurrent episodes of watery diarrhea and failure to thrive in early infancy despite standard treatment. Molecular testing identified that our patient had a compound heterozygous variant in SLC5A1. Fructose-based formulae have been proven to be effective in treating GGM. This case highlights the importance of early diagnosis and timely management to prevent serious complications of undiagnosed GGM.
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Affiliation(s)
- Loujen O Alamoudi
- College of Medicine, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Centre, King Abdulaziz Medical City, Ministry of the National Guard - Health Affairs, Jeddah, SAU
| | - Albaraa T Alfaraidi
- College of Medicine, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Centre, King Abdulaziz Medical City, Ministry of the National Guard - Health Affairs, Jeddah, SAU
| | | | - Majid S Al-Thaqafy
- Infection Prevention and Control, Ministry of the National Guard - Health Affairs, Jeddah, SAU.,College of Medicine, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Centre, King Abdulaziz Medical City, Ministry of the National Guard - Health Affairs, Jeddah, SAU
| | - Mohammed Hasosah
- Pediatric Gastroenterology, Ministry of the National Guard - Health Affairs, Jeddah, SAU.,College of Medicine, King Saud bin Abdulaziz University for Health Sciences, King Abdullah International Medical Research Centre, King Abdulaziz Medical City, Ministry of the National Guard - Health Affairs, Jeddah, SAU
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9
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Murakata M. Synthesis of C-Arylglucosides as SGLT2 Inhibitors. J SYN ORG CHEM JPN 2021. [DOI: 10.5059/yukigoseikyokaishi.79.532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Masatoshi Murakata
- API Process Development Department, Pharmaceutical Technology Division, Chugai Pharmaceutical Co., LTD
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de Laat MA, Sillence MN. A review of recent developments in the pharmacological prevention and treatment of endocrinopathic laminitis. ANIMAL PRODUCTION SCIENCE 2020. [DOI: 10.1071/an19491] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Despite the prevalence of endocrinopathic laminitis, the pharmacologic options for preventing and treating the disease are severely limited. The present review aims to discuss the spectrum of potential therapeutic agents for the condition, ranging from early experimental compounds to agents nearing registration. There are different pharmacologic targets for, and approaches to, managing laminitis. Reducing hyperinsulinaemia is central to diminishing endocrinopathic laminitis risk, and a detailed understanding of the pathophysiology of insulin dysregulation is necessary to identify pathways that can be targeted to minimise post-prandial insulin secretion and action. This area of research is advancing rapidly, with several exciting prospects, such as sodium-dependent glucose co-transporter-2 inhibitors, on the horizon for the treatment of equine metabolic dysfunction. Drugs that directly target the lamellae and aim to reduce the damage inflicted on the lamellae as part of this condition, are not yet available. Although progress in this area of laminitis therapy is slower, improved understanding of the events that lead to lamellar failure has enabled the investigation of novel drugs that aim to prevent laminitis at the site of the lesion. Finally, a brief review is included of the directions being taken in the management of the chronic and acute pain that accompanies laminitis. Medications for relieving the pain associated with laminitis are currently the most-prescribed drugs for the disease, and range from simple, affordable and thoroughly tested options, such as phenylbutazone, to newer, less-understood applications such as paracetamol and gabapentin. In the future, endocrinopathic laminitis management plans will likely take a multi-faceted approach that still hinge on effective dietary management and exercise, but also include drugs that address foot pathology, pain and underlying endocrine disturbances.
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11
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Fructose, galactose and glucose – In health and disease. Clin Nutr ESPEN 2019; 33:18-28. [DOI: 10.1016/j.clnesp.2019.07.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 06/07/2019] [Accepted: 07/08/2019] [Indexed: 01/01/2023]
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Rendell MS. The journey from gene knockout to clinical medicine: telotristat and sotagliflozin. DRUG DESIGN DEVELOPMENT AND THERAPY 2019; 13:817-824. [PMID: 30880915 PMCID: PMC6408923 DOI: 10.2147/dddt.s144556] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Gene knockout has been a powerful technique to evaluate the physiologic role of selected gene products. Lexicon pioneered high-throughput gene knockout technology and went further in designing agents to inhibit products of gene expression. Two agents have entered late-stage development. Telotristat is an inhibitor of tryptophan hydroxylase (TPH), preventing the production of serotonin. Although this agent blocks the two isoforms of TPH, it does not cross the blood–brain barrier, thus avoiding central neurologic manifestations. It inhibits the peripheral production of serotonin, and in particular prevents serotonin action in the intestines, resulting in decreased peristaltic action. Lexicon successfully developed telotristat to treat carcinoid syndrome not responding adequately to somatostatin inhibitors. Sotagliflozin development proceeded from the observation that dual inhibition of SGLT2 in the kidneys and SGLT1 in the intestines resulted in increased renal glucose excretion, reduced early-phase glucose absorption, as well as increased blood levels of GLP-1 and PYY. Initial development efforts focused on type 1 diabetes and have shown reduced postprandial glucose levels, less tendency to hypoglycemia, and lower HbA1c. Several other SGLT2 inhibitors have been associated with increased frequency of diabetic ketoacidosis (DKA). In the type 1 trials, sotagliflozin-treated individuals experienced DKA at a higher rate than placebo-treated patients. The sotagliflozin development program has now been extended to trials on type 2 diabetes. Long-term clinical trials will determine the benefits and risks of the agent in comparison to other currently marketed SGLT2 inhibitors.
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Affiliation(s)
- Marc S Rendell
- Association of Diabetes Investigators, Omaha, NE 68131, USA, .,Rose Salter Medical Research Foundation, Newport Coast, CA 92657, USA,
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13
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Turpin D, Langendijk P, Sharp C, Pluske J. Improving welfare and production in the peri-weaning period: Effects of co-mingling and intermittent suckling on the stress response, performance, behaviour, and gastrointestinal tract carbohydrate absorption in young pigs. Livest Sci 2017. [DOI: 10.1016/j.livsci.2017.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Intermittent Suckling in Combination with an Older Weaning Age Improves Growth, Feed Intake and Aspects of Gastrointestinal Tract Carbohydrate Absorption in Pigs after Weaning. Animals (Basel) 2016; 6:ani6110066. [PMID: 27792138 PMCID: PMC5126768 DOI: 10.3390/ani6110066] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/19/2016] [Accepted: 10/16/2016] [Indexed: 11/17/2022] Open
Abstract
Simple Summary The weaning of piglets involves abrupt changes that often cause reduced production and predisposition to gastrointestinal tract dysfunction. Increasing the weaning age or using gradual weaning are techniques that can improve post-weaning performance. In this study, it is shown that an older weaning age (day 35) in combination with intermittent suckling (daily separation of piglets from the sow for 8 h in the week before weaning) improved growth rate, feed intake and aspects of gastrointestinal tract carbohydrate absorption after weaning. However, intermittent suckling and weaning at 28 days did not seem to improve post-weaning performance in this study. Abstract This study tested the hypothesis that intermittent suckling (IS) with or without an older weaning age would improve post-weaning gastrointestinal tract (GIT) carbohydrate absorptive capacity in pigs while reducing post-weaning stress and aspects of the inflammatory response. Three weaning regimes using primiparous sows were compared: (1) conventional weaning (CW28) (n = 22), where piglets were weaned conventionally at day 28; (2) IS28 (n = 21), where IS started at day 21 until weaning at day 28; and (3) IS35 (n = 21), where IS started at day 28 until weaning at day 35. Sugar absorption tests (10% mannitol or 10% galactose) were used to measure GIT absorptive capacity. All measured parameters were compared in relation to weaning across treatments (i.e., different physiological ages were compared). The IS35 pigs grew fastest in the 12 days after weaning (p < 0.01) and had the highest solid feed intake before and after weaning (p < 0.05). Irrespective of treatment, pre-weaning mannitol levels were higher than post-weaning levels (p < 0.01), whereas post-weaning galactose levels were highest in IS35 pigs (p < 0.01). Cytokine data did not show any treatment effects. In conclusion, these data suggest that IS in combination with an older weaning age (day 35) improved post-weaning adaptation as evidenced by improvements in performance measures and galactose absorption. However, IS28 did not improve post-weaning performance.
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Song P, Onishi A, Koepsell H, Vallon V. Sodium glucose cotransporter SGLT1 as a therapeutic target in diabetes mellitus. Expert Opin Ther Targets 2016; 20:1109-25. [PMID: 26998950 DOI: 10.1517/14728222.2016.1168808] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Glycemic control is important in diabetes mellitus to minimize the progression of the disease and the risk of potentially devastating complications. Inhibition of the sodium-glucose cotransporter SGLT2 induces glucosuria and has been established as a new anti-hyperglycemic strategy. SGLT1 plays a distinct and complementing role to SGLT2 in glucose homeostasis and, therefore, SGLT1 inhibition may also have therapeutic potential. AREAS COVERED This review focuses on the physiology of SGLT1 in the small intestine and kidney and its pathophysiological role in diabetes. The therapeutic potential of SGLT1 inhibition, alone as well as in combination with SGLT2 inhibition, for anti-hyperglycemic therapy are discussed. Additionally, this review considers the effects on other SGLT1-expressing organs like the heart. EXPERT OPINION SGLT1 inhibition improves glucose homeostasis by reducing dietary glucose absorption in the intestine and by increasing the release of gastrointestinal incretins like glucagon-like peptide-1. SGLT1 inhibition has a small glucosuric effect in the normal kidney and this effect is increased in diabetes and during inhibition of SGLT2, which deliver more glucose to SGLT1 in late proximal tubule. In short-term studies, inhibition of SGLT1 and combined SGLT1/SGLT2 inhibition appeared to be safe. More data is needed on long-term safety and cardiovascular consequences of SGLT1 inhibition.
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Affiliation(s)
- Panai Song
- a Division of Nephrology & Hypertension, Department of Medicine , University of California San Diego , La Jolla , CA , USA.,b VA San Diego Healthcare System , San Diego , CA , USA.,c Department of Nephrology, Second Xiangya Hospital , Central South University , Changsha , China
| | - Akira Onishi
- a Division of Nephrology & Hypertension, Department of Medicine , University of California San Diego , La Jolla , CA , USA.,b VA San Diego Healthcare System , San Diego , CA , USA.,d Division of Nephrology, Department of Medicine , Jichi Medical University , Shimotsuke , Japan
| | - Hermann Koepsell
- e Department of Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute , University of Würzburg , Würzburg , Germany
| | - Volker Vallon
- a Division of Nephrology & Hypertension, Department of Medicine , University of California San Diego , La Jolla , CA , USA.,b VA San Diego Healthcare System , San Diego , CA , USA.,f Department of Pharmacology , University of California San Diego , La Jolla , CA , USA
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16
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Naftalin RJ. A computer model simulating human glucose absorption and metabolism in health and metabolic disease states. F1000Res 2016; 5:647. [PMID: 27347379 PMCID: PMC4909112 DOI: 10.12688/f1000research.8299.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/31/2016] [Indexed: 12/16/2022] Open
Abstract
A computer model designed to simulate integrated glucose-dependent changes in splanchnic blood flow with small intestinal glucose absorption, hormonal and incretin circulation and hepatic and systemic metabolism in health and metabolic diseases e.g. non-alcoholic fatty liver disease, (NAFLD), non-alcoholic steatohepatitis, (NASH) and type 2 diabetes mellitus, (T2DM) demonstrates how when glucagon-like peptide-1, (GLP-1) is synchronously released into the splanchnic blood during intestinal glucose absorption, it stimulates superior mesenteric arterial (SMA) blood flow and by increasing passive intestinal glucose absorption, harmonizes absorption with its distribution and metabolism. GLP-1 also synergises insulin-dependent net hepatic glucose uptake (NHGU). When GLP-1 secretion is deficient post-prandial SMA blood flow is not increased and as NHGU is also reduced, hyperglycaemia follows. Portal venous glucose concentration is also raised, thereby retarding the passive component of intestinal glucose absorption. Increased pre-hepatic sinusoidal resistance combined with portal hypertension leading to opening of intrahepatic portosystemic collateral vessels are NASH-related mechanical defects that alter the balance between splanchnic and systemic distributions of glucose, hormones and incretins.The model reveals the latent contribution of portosystemic shunting in development of metabolic disease. This diverts splanchnic blood content away from the hepatic sinuses to the systemic circulation, particularly during the glucose absorptive phase of digestion, resulting in inappropriate increases in insulin-dependent systemic glucose metabolism. This hastens onset of hypoglycaemia and thence hyperglucagonaemia. The model reveals that low rates of GLP-1 secretion, frequently associated with T2DM and NASH, may be also be caused by splanchnic hypoglycaemia, rather than to intrinsic loss of incretin secretory capacity. These findings may have therapeutic implications on GLP-1 agonist or glucagon antagonist usage.
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Affiliation(s)
- Richard J Naftalin
- Departments of Physiology and Vascular Biology, BHF centre of research excellence, King's College London School of Medicine, London, UK
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17
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Diagnosing and Treating Intolerance to Carbohydrates in Children. Nutrients 2016; 8:157. [PMID: 26978392 PMCID: PMC4808885 DOI: 10.3390/nu8030157] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 02/22/2016] [Accepted: 02/25/2016] [Indexed: 12/19/2022] Open
Abstract
Intolerance to carbohydrates is relatively common in childhood, but still poorly recognized and managed. Over recent years it has come to the forefront because of progresses in our knowledge on the mechanisms and treatment of these conditions. Children with intolerance to carbohydrates often present with unexplained signs and symptoms. Here, we examine the most up-to-date research on these intolerances, discuss controversies relating to the diagnostic approach, including the role of molecular analysis, and provide new insights into modern management in the pediatric age, including the most recent evidence for correct dietary treatment.
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18
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Affiliation(s)
- Hiroyuki Kakinuma
- Medicinal Chemistry 2, Chemistry Laboratories, Taisho Pharmaceutical Co., Ltd
| | - Takahiro Oi
- Process Chemistry, Pharmaceutical Science Laboratories, Taisho Pharmaceutical Co., Ltd
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Rosenstock J, Cefalu WT, Lapuerta P, Zambrowicz B, Ogbaa I, Banks P, Sands A. Greater dose-ranging effects on A1C levels than on glucosuria with LX4211, a dual inhibitor of SGLT1 and SGLT2, in patients with type 2 diabetes on metformin monotherapy. Diabetes Care 2015; 38:431-8. [PMID: 25216510 PMCID: PMC5131876 DOI: 10.2337/dc14-0890] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 08/14/2014] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To assess the dose-ranging efficacy and safety of LX4211, a dual inhibitor of sodium-glucose cotransporter (SGLT) 1 and SGLT2, in type 2 diabetes. RESEARCH DESIGN AND METHODS Type 2 diabetic patients inadequately controlled on metformin were randomly assigned to 75 mg once daily, 200 mg once daily, 200 mg twice daily, or 400 mg once daily of LX4211 or placebo. Primary end point was A1C change from baseline to week 12. Secondary end points included changes in blood pressure (BP) and body weight. RESULTS Baseline characteristics in 299 patients randomly assigned to LX4211 or placebo in this 12-week dose-ranging study were similar: mean age 55.9 years, A1C 8.1% (65 mmol/mol), BMI 33.1 kg/m(2), and BP 124/79 mmHg. LX4211 significantly reduced A1C to week 12 in a dose-dependent manner by 0.42% (4.6 mmol/mol), 0.52% (5.7 mmol/mol), 0.80% (8.7 mmol/mol), and 0.92% (10.0 mmol/mol), respectively (P < 0.001 each), compared with 0.09% (1.0 mmol/mol) for placebo. Greater A1C reductions were produced by 400 mg once a day than 200 mg once a day LX4211 without higher urinary glucose excretion, suggesting a contribution of SGLT1 inhibition. Significant reductions were seen in body weight (-1.85 kg; P < 0.001) and systolic BP (-5.7 mmHg; P < 0.001), but diastolic BP was unchanged (-1.6; P = 0.164). Adverse events with LX4211 were mild to moderate and similar to placebo, including urinary tract infections and gastrointestinal-related events; genital infections were limited to LX4211 groups (0-5.0%). No hypoglycemia occurred. CONCLUSIONS Dual inhibition of SGLT1/SGLT2 with LX4211 produced significant dose-ranging improvements in glucose control without dose-increasing glucosuria and was associated with reductions in weight and systolic BP in metformin-treated patients with type 2 diabetes.
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Affiliation(s)
- Julio Rosenstock
- Dallas Diabetes and Endocrine Center at Medical City, Dallas, TX
| | - William T Cefalu
- Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA
| | | | | | - Ike Ogbaa
- Lexicon Pharmaceuticals, Inc., The Woodlands, TX
| | | | - Arthur Sands
- Lexicon Pharmaceuticals, Inc., The Woodlands, TX
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20
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Neundlinger I, Puntheeranurak T, Wildling L, Rankl C, Wang LX, Gruber HJ, Kinne RKH, Hinterdorfer P. Forces and dynamics of glucose and inhibitor binding to sodium glucose co-transporter SGLT1 studied by single molecule force spectroscopy. J Biol Chem 2014; 289:21673-83. [PMID: 24962566 DOI: 10.1074/jbc.m113.529875] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Single molecule force spectroscopy was employed to investigate the dynamics of the sodium glucose co-transporter (SGLT1) upon substrate and inhibitor binding on the single molecule level. CHO cells stably expressing rbSGLT1 were probed by using atomic force microscopy tips carrying either thioglucose, 2'-aminoethyl β-d-glucopyranoside, or aminophlorizin. Poly(ethylene glycol) (PEG) chains of different length and varying end groups were used as tether. Experiments were performed at 10, 25 and 37 °C to address different conformational states of SGLT1. Unbinding forces between ligands and SGLT1 were recorded at different loading rates by changing the retraction velocity, yielding binding probability, width of energy barrier of the binding pocket, and the kinetic off rate constant of the binding reaction. With increasing temperature, width of energy barrier and average life time increased for the interaction of SGLT1 with thioglucose (coupled via acrylamide to a long PEG) but decreased for aminophlorizin binding. The former indicates that in the membrane-bound SGLT1 the pathway to sugar translocation involves several steps with different temperature sensitivity. The latter suggests that also the aglucon binding sites for transport inhibitors have specific, temperature-sensitive conformations.
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Affiliation(s)
- Isabel Neundlinger
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Theeraporn Puntheeranurak
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria, Department of Biology, Faculty of Science, Mahidol University and Nanotec-MU Center of Excellence on Intelligent Materials and Systems, 272 Rama VI, Ratchathewi, Bangkok 10400, Thailand
| | - Linda Wildling
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | | | - Lai-Xi Wang
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, and
| | - Hermann J Gruber
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria
| | - Rolf K H Kinne
- Max Planck Institute of Molecular Physiology, Otto-Hahn Strasse 11, 44227 Dortmund, Germany
| | - Peter Hinterdorfer
- From the Institute for Biophysics, Johannes Kepler University of Linz, Gruberstrasse 40, 4020 Linz, Austria,
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Abstract
Glucose galactose malabsorption (GGM) is a rare autosomal recessive disorder characterized by life-threatening osmotic diarrhea at infancy. When the intake of the offending sugars (namely, glucose, galactose and lactose) is ceased, the diarrhea promptly stops. Mutations in the SLC5A1 gene, encoding the sodium-glucose co-transporter located in the brush border of enterocytes, have been shown to cause the disease. More than 300 subjects of diverse origin have been reported worldwide, most of whom are a result of a consanguineous union. We examined 6 patients from 4 families presenting with complaints consistent with GGM and responsive to the appropriate fructose-based diet. Genomic DNA of the patients was polymerase chain reaction amplified for each of the 15 exons of the SLC5A1 gene and analyzed by nucleotide sequencing. The analysis lead to the identification of 2 novel mutations: a 1915 del C mutation, a frameshift mutation leading to a premature stop at codon 645; and a substitution missense mutation of T to C on nucleotide 947 (exon 9) causing a L316P substitution. In addition, G426R and C255W mutations previously described were identified; in both cases, the patients were shown to be homozygous and their parents heterozygous for the mutation. Of note, additional patients who underwent a similar evaluation at our center for suspected GGM did not show mutations in the SLC5A1 gene. Because the latter did not previously undergo a diagnostic algorithm in full, for instance, one that may consist of a glucose breath hydrogen test and an empiric attempt of a dietary switch to galactomin, we suggest that molecular genotyping of such patients should only follow such appropriate clinical evaluation.
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Tirmenstein M, Dorr TE, Janovitz EB, Hagan D, Abell LM, Onorato JM, Whaley JM, Graziano MJ, Reilly TP. Nonclinical Toxicology Assessments Support the Chronic Safety of Dapagliflozin, a First-in-Class Sodium-Glucose Cotransporter 2 Inhibitor. Int J Toxicol 2013; 32:336-50. [DOI: 10.1177/1091581813505331] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Dapagliflozin, a first-in-class, selective inhibitor of sodium-glucose cotransporter 2 (SGLT2), promotes urinary glucose excretion to reduce hyperglycemia for the treatment of type 2 diabetes. A series of nonclinical studies were undertaken to evaluate dapagliflozin in species where it was shown to have pharmacologic activity comparable with that in humans at doses that resulted in supratherapeutic exposures. In vitro screening (>300 targets; 10 μmol/L) indicated no significant off-target activities for dapagliflozin or its primary human metabolite. Once daily, orally administered dapagliflozin was evaluated in Sprague-Dawley rats (≤6 months) and in beagle dogs (≤1 year) at exposures >5000-fold those observed at the maximum recommended human clinical dose (MRHD; 10 mg). Anticipated, pharmacologically mediated effects of glucosuria, osmotic diuresis, and mild electrolyte loss were observed, but there were no adverse effects at clinically relevant exposures, including in the kidneys or urogenital tract. The SGLT2−/− mice, which show chronic glucosuria, and dapagliflozin-treated, wild-type mice exhibited similar safety profiles. In rats but not dogs, dapagliflozin at >2000-fold MRHD exposures resulted in tissue mineralization and trabecular bone accretion. Investigative studies suggested that the effect was not relevant to human safety, since it was partially related to off-target inhibition of SGLT1, which was observed only at high doses of dapagliflozin and resulted in intestinal glucose malabsorption and increased intestinal calcium absorption. The rigorous assessment of supra- and off-target dapagliflozin pharmacology in nonclinical species allowed for a thorough evaluation of potential toxicity, providing us with confidence in its safety in patients with diabetes.
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Affiliation(s)
- Mark Tirmenstein
- Bristol-Myers Squibb, Drug Safety Evaluation, Research and Development, New Brunswick, NJ, USA
| | - Thomas E. Dorr
- Bristol-Myers Squibb, Drug Safety Evaluation, Research and Development, New Brunswick, NJ, USA
| | - Evan B. Janovitz
- Bristol-Myers Squibb, Discovery Toxicology, Research and Development, Hopewell, NJ, USA
| | - Deborah Hagan
- Bristol-Myers Squibb, Metabolic Disease Discovery Biology, Hopewell, NJ, USA
| | - Lynn M. Abell
- Bristol-Myers Squibb, Lead Evaluation and Mechanistic Biochemistry, Molecular Sciences and Candidate Optimization, Research and Development, Hopewell, NJ, USA
| | - Joelle M. Onorato
- Bristol-Myers Squibb, Bioanalytical and Discovery Analytical Sciences, Research and Development, Hopewell, NJ, USA
| | - Jean M. Whaley
- Bristol-Myers Squibb, Metabolic Disease Discovery Biology, Hopewell, NJ, USA
| | - Michael J. Graziano
- Bristol-Myers Squibb, Drug Safety Evaluation, Research and Development, Princeton, NJ, USA
| | - Timothy P. Reilly
- Bristol-Myers Squibb, Drug Safety Evaluation, Research and Development, Princeton, NJ, USA
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23
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Zambrowicz B, Freiman J, Brown PM, Frazier KS, Turnage A, Bronner J, Ruff D, Shadoan M, Banks P, Mseeh F, Rawlins DB, Goodwin NC, Mabon R, Harrison BA, Wilson A, Sands A, Powell DR. LX4211, a dual SGLT1/SGLT2 inhibitor, improved glycemic control in patients with type 2 diabetes in a randomized, placebo-controlled trial. Clin Pharmacol Ther 2012; 92:158-69. [PMID: 22739142 PMCID: PMC3400893 DOI: 10.1038/clpt.2012.58] [Citation(s) in RCA: 182] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Thirty-six patients with type 2 diabetes mellitus (T2DM) were randomized 1:1:1 to receive a once-daily oral dose of placebo or 150 or 300 mg of the dual SGLT1/SGLT2 inhibitor LX4211 for 28 days. Relative to placebo, LX4211 enhanced urinary glucose excretion by inhibiting SGLT2-mediated renal glucose reabsorption; markedly and significantly improved multiple measures of glycemic control, including fasting plasma glucose, oral glucose tolerance, and HbA(1c); and significantly lowered serum triglycerides. LX4211 also mediated trends for lower weight, lower blood pressure, and higher glucagon-like peptide-1 levels. In a follow-up single-dose study in 12 patients with T2DM, LX4211 (300 mg) significantly increased glucagon-like peptide-1 and peptide YY levels relative to pretreatment values, probably by delaying SGLT1-mediated intestinal glucose absorption. In both studies, LX4211 was well tolerated without evidence of increased gastrointestinal side effects. These data support further study of LX4211-mediated dual SGLT1/SGLT2 inhibition as a novel mechanism of action in the treatment of T2DM.
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Affiliation(s)
- B Zambrowicz
- Lexicon Pharmaceuticals, Inc., The Woodlands, Texas, USA
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24
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Structural Insights into Genetic Variants of Na+/Glucose Cotransporter SGLT1 Causing Glucose–Galactose Malabsorption: vSGLT as a Model Structure. Cell Biochem Biophys 2012; 63:151-8. [DOI: 10.1007/s12013-012-9352-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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25
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Liang Y, Arakawa K, Ueta K, Matsushita Y, Kuriyama C, Martin T, Du F, Liu Y, Xu J, Conway B, Conway J, Polidori D, Ways K, Demarest K. Effect of canagliflozin on renal threshold for glucose, glycemia, and body weight in normal and diabetic animal models. PLoS One 2012; 7:e30555. [PMID: 22355316 PMCID: PMC3280264 DOI: 10.1371/journal.pone.0030555] [Citation(s) in RCA: 180] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 12/19/2011] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Canagliflozin is a sodium glucose co-transporter (SGLT) 2 inhibitor in clinical development for the treatment of type 2 diabetes mellitus (T2DM). METHODS (14)C-alpha-methylglucoside uptake in Chinese hamster ovary-K cells expressing human, rat, or mouse SGLT2 or SGLT1; (3)H-2-deoxy-d-glucose uptake in L6 myoblasts; and 2-electrode voltage clamp recording of oocytes expressing human SGLT3 were analyzed. Graded glucose infusions were performed to determine rate of urinary glucose excretion (UGE) at different blood glucose (BG) concentrations and the renal threshold for glucose excretion (RT(G)) in vehicle or canagliflozin-treated Zucker diabetic fatty (ZDF) rats. This study aimed to characterize the pharmacodynamic effects of canagliflozin in vitro and in preclinical models of T2DM and obesity. RESULTS Treatment with canagliflozin 1 mg/kg lowered RT(G) from 415±12 mg/dl to 94±10 mg/dl in ZDF rats while maintaining a threshold relationship between BG and UGE with virtually no UGE observed when BG was below RT(G). Canagliflozin dose-dependently decreased BG concentrations in db/db mice treated acutely. In ZDF rats treated for 4 weeks, canagliflozin decreased glycated hemoglobin (HbA1c) and improved measures of insulin secretion. In obese animal models, canagliflozin increased UGE and decreased BG, body weight gain, epididymal fat, liver weight, and the respiratory exchange ratio. CONCLUSIONS Canagliflozin lowered RT(G) and increased UGE, improved glycemic control and beta-cell function in rodent models of T2DM, and reduced body weight gain in rodent models of obesity.
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MESH Headings
- Animals
- Blood Glucose/metabolism
- Body Weight/drug effects
- CHO Cells
- Canagliflozin
- Cells, Cultured
- Cricetinae
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/pathology
- Glucose Tolerance Test
- Glucosides/therapeutic use
- Humans
- Hyperglycemia/drug therapy
- Hyperglycemia/metabolism
- Hyperglycemia/pathology
- Kidney/drug effects
- Kidney/physiopathology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Obese
- Muscle, Skeletal/cytology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Rats
- Rats, Zucker
- Sodium-Glucose Transport Proteins/genetics
- Sodium-Glucose Transport Proteins/metabolism
- Sodium-Glucose Transporter 1/genetics
- Sodium-Glucose Transporter 1/metabolism
- Sodium-Glucose Transporter 2/genetics
- Sodium-Glucose Transporter 2/metabolism
- Sodium-Glucose Transporter 2 Inhibitors
- Thiophenes/therapeutic use
- Weight Gain/drug effects
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Affiliation(s)
- Yin Liang
- Johnson & Johnson Pharmaceutical Research & Development, LLC, Spring House, Pennsylvania, United States of America.
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Wei N, Liu R, Ou Y, Li X, Qiang O, Guo W, Tang CW. Effects of octreotide on glucose transporter type 2 expression in obese rat small intestine. World J Gastroenterol 2011; 17:4434-9. [PMID: 22110271 PMCID: PMC3218159 DOI: 10.3748/wjg.v17.i39.4434] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 04/05/2011] [Accepted: 04/12/2011] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effects of the somatostatin analogue, octreotide, on maltose and sucrase activities and expression of glucose transporter type 2 (GLUT2) in obese rat intestinal mucosa.
METHODS: We divided 49 Sprague-Dawley rats into a group of 31 high fat diet-induced obese rats and a group of 18 normal controls. The obese rats were separated into an octreotide treated group of 16 rats and an obese group of 15. The intervention group was injected with octreotide at 40 μg/kg body weight every 12 h for 8 d. Rat body weight was measured weekly to calculate Lee’s index. After euthanization, maltase and sucrase activities in the small intestine were measured by activity assays, and the fasting plasma glucose level was measured. The expression of GLUT2 in small intestinal mucosa was analyzed by immunohistochemistry, reverse transcriptase polymerase chain reaction and Western blotting assays.
RESULTS: Body weight, Lee’s index, fasting plasma glucose level, maltase activity in small intestinal mucosa, mucosa and apical GLUT2, GLUT2 mRNA and protein expression levels were all significantly higher in the obese group than in the normal control group (605.61 ± 141.00 vs 378.54 ± 111.75, 337.61 ± 10.82 vs 318.73 ± 20.10, 8.60 ± 1.38 vs 7.33 ± 0.70, 156.01 ± 58.81 vs 50.43 ± 30.49, 390 744.2 ± 62 469.21 vs 170 546.50 ± 50 646.14, 26 740.18 ± 3809.60 vs 354.98 ± 57.19, 0.26 ± 0.11 vs 0.07 ± 0.02, and 2.08 ± 0.59 vs 1.27 ± 0.38, respectively, all P < 0.01). Sucrase activity did not differ between the two groups. Octreotide intervention significantly decreased the body weight and fasting plasma glucose level of obese rats (508.27 ± 94.39 vs 605.61 ± 141.00, 7.58 ± 1.51 vs 8.60 ±1.38, respectively, all P < 0.05). The intestinal mucosa and apical GLUT2, expression of GLUT2 mRNA and protein were also significantly lower in the octreotide intervention group than in the obese group (269 975.2 ± 53 730.94 vs 390 744.2 ± 62 469.21, 3758.06 ±364.51 vs 26 740.18 ± 3809.60, 0.08 ± 0.02 vs 0.26 ±0.11, and 1.31 ± 0.27 vs 2.08 ± 0.59, respectively, all P < 0.01).
CONCLUSION: High fat diet-induced obesity is associated with elevated intestinal maltase activity, GLUT2 expression, and permanent apical GLUT2 in the small intestinal mucosa of rats. Octreotide can inhibit these effects.
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Sterling KM, Ahearn GA. Glucose and fructose uptake by Limulus polyphemus hepatopancreatic brush border and basolateral membrane vesicles: evidence for Na+-dependent sugar transport activity. J Comp Physiol B 2010; 181:467-75. [PMID: 21184084 DOI: 10.1007/s00360-010-0543-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 11/29/2010] [Accepted: 12/02/2010] [Indexed: 11/28/2022]
Abstract
[(3)H]-fructose and [(3)H]-glucose transport activities were determined in brush border membrane vesicles (BBMV) and basolateral membrane vesicles (BLMV) from Limulus polyphemus (horseshoe crab) hepatopancreas. Glucose transport was equilibrative in the absence of sodium and sodium dependent in the presence of sodium in BBMV, suggesting GLUT-like and SGLT-like transport activity. Glucose transport by BLMV was equilibrative and sodium independent. Fructose uptake by BBMV and BLMV was equilibrative in the absence of sodium and sodium dependent in the presence of sodium. Western blot analysis using a rabbit anti-mouse SGLT-1 polyclonal antibody indicated the presence of a cross-reacting horseshoe crab BBMV protein of similar molecular weight to the mammalian SGLT1. Sequence alignment of the mouse SGLT-4 and SGLT1 with a translated, horseshoe crab-expressed sequence tag also indicated significant identity between species. Fructose and glucose uptake in the absence and presence of sodium by hepatopancreas BBMV and BLMV indicated the presence of sodium-dependent transport activity for each sugar that may result from the presence of transporters similar to those described for other species.
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Affiliation(s)
- Kenneth M Sterling
- Department of Biology, University of North Florida, 1 UNF Drive, Jacksonville, FL 32224, USA
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La Ferla B, Spinosa V, D'Orazio G, Palazzo M, Balsari A, Foppoli AA, Rumio C, Nicotra F. Dansyl C-Glucoside as a Novel Agent Against Endotoxic Shock. ChemMedChem 2010; 5:1677-80. [DOI: 10.1002/cmdc.201000282] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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29
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Longpré JP, Gagnon DG, Coady MJ, Lapointe JY. The actual ionic nature of the leak current through the Na+/glucose cotransporter SGLT1. Biophys J 2010; 98:231-9. [PMID: 20338844 DOI: 10.1016/j.bpj.2009.10.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 10/07/2009] [Accepted: 10/08/2009] [Indexed: 11/28/2022] Open
Abstract
Expression of the Na(+)/glucose cotransporter SGLT1 in Xenopus oocytes is characterized by a phlorizin-sensitive leak current (in the absence of glucose) that was originally called a "Na(+) leak" and represents some 5-10% of the maximal Na(+)/glucose cotransport current. We analyzed the ionic nature of the leak current using a human SGLT1 mutant (C292A) displaying a threefold larger leak current while keeping a reversal potential (V(R)) of approximately -15 mV as observed for wt SGLT1. V(R) showed only a modest negative shift when extracellular Na(+) concentration ([Na(+)](o)) was lowered and it was completely insensitive to changes in extracellular Cl(-). When extracellular pH (pH(o)) was decreased from 7.5 to 6.5 and 5.5, V(R) shifted by +15 and +40 mV, respectively, indicating that protons may be the main charge carrier at low pH(o) but other ions must be involved at pH(o) 7.5. In the presence of 15 mM [Na(+)](o) (pH(o) = 7.5), addition of 75 mM of either Na(+), Li(+), Cs(+), or K(+) generated similar increases in the leak current amplitude. This observation, which was confirmed with wt SGLT1, indicates a separate pathway for the leak current with respect to the cotransport current. This means that, contrary to previous beliefs, the leak current cannot be accounted for by the translocation of the Na-loaded and glucose-free cotransporter. Using chemical modification and different SGLT1 mutants, a relationship was found between the cationic leak current and the passive water permeability suggesting that water and cations may share a common pathway through the cotransporter.
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Affiliation(s)
- Jean-Philippe Longpré
- Groupe d'Etude des Protéines Membranaires, Département de Physique, Université de Montréal, Montréal, Québec, Canada
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Chao EC, Henry RR. SGLT2 inhibition--a novel strategy for diabetes treatment. Nat Rev Drug Discov 2010; 9:551-9. [PMID: 20508640 DOI: 10.1038/nrd3180] [Citation(s) in RCA: 546] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Inhibiting sodium-glucose co-transporters (SGLTs), which have a key role in the reabsorption of glucose in the kidney, has been proposed as a novel therapeutic strategy for diabetes. Genetic mutations in the kidney-specific SGLT2 isoform that result in benign renal glycosuria, as well as preclinical and clinical studies with SGLT2 inhibitors in type 2 diabetes, support the potential of this approach. These investigations indicate that elevating renal glucose excretion by suppressing SGLT2 can reduce plasma glucose levels, as well as decrease weight. Although data from ongoing Phase III trials of these agents are needed to more fully assess safety, results suggest that the beneficial effects of SGLT2 inhibition might be achieved without exerting significant side effects--an advantage over many current diabetes medications. This article discusses the role of SGLT2 in glucose homeostasis and the evidence available so far on the therapeutic potential of blocking these transporters in the treatment of diabetes.
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Affiliation(s)
- Edward C Chao
- Section of Endocrinology, Metabolism and Diabetes, VA San Diego Healthcare System and University of California, San Diego School of Medicine, 3350 La Jolla Village Drive, 111 G San Diego, California 92161, USA.
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Abstract
Considerable data have accumulated over the past 20 years, indicating that the human kidney is involved in the regulation of glucose via gluconeogenesis, taking up glucose from the circulation, and by reabsorbing glucose from the glomerular filtrate. In light of the development of glucose-lowering drugs involving inhibition of renal glucose reabsorption, this review summarizes these data. Medline was searched from 1989 to present using the terms 'renal gluconeogenesis', 'renal glucose utilization', 'diabetes mellitus' and 'glucose transporters'. The human liver and kidneys release approximately equal amounts of glucose via gluconeogenesis in the post-absorptive state. In the postprandial state, although overall endogenous glucose release decreases substantially, renal gluconeogenesis increases by approximately twofold. Glucose utilization by the kidneys after an overnight fast accounts for approximately 10% of glucose utilized by the body. Following a meal, glucose utilization by the kidney increases. Normally each day, approximately 180 g of glucose is filtered by the kidneys; almost all of this is reabsorbed by means of sodium-glucose co-transporter 2 (SGLT2), expressed in the proximal tubules. However, the capacity of SGLT2 to reabsorb glucose from the renal tubules is finite and, when plasma glucose concentrations exceed a threshold, glucose appears in the urine. Handling of glucose by the kidney is altered in Type 2 diabetes mellitus (T2DM): renal gluconeogenesis and renal glucose uptake are increased in both the post-absorptive and postprandial states, and renal glucose reabsorption is increased. Specific SGLT2 inhibitors are being developed as a novel means of controlling hyperglycaemia in T2DM.
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Affiliation(s)
- J E Gerich
- University of Rochester School of Medicine, Rochester, NY 14642, USA.
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Schulzke JD, Tröger H, Amasheh M. Disorders of intestinal secretion and absorption. Best Pract Res Clin Gastroenterol 2009; 23:395-406. [PMID: 19505667 DOI: 10.1016/j.bpg.2009.04.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The gastrointestinal tract possesses a huge epithelial surface area and performs many different tasks. Amongst them are the digestive and absorptive functions. Disorders of intestinal absorption and secretion comprise a variety of different diseases, e.g. coeliac disease, lactase deficiency or Whipple's disease. In principle, impaired small intestinal function can occur with or without morphological alterations of the intestinal mucosa. Therefore, in the work up of a malabsorptive syndrome an early small intestinal biopsy is encouraged in conjunction with breath tests and stool analysis to guide further management. In addition, there is an array of functional tests, the clinical availability of which becomes more and more limited. In any case, early diagnosis of the underlying pathophysiology is most important, in order to initiate proper therapy. In this chapter, diagnostic procedure of malabsorption is discussed with special attention to specific disease like coeliac disease, Whipple's disease, giardiasis and short bowel syndrome. Furthermore, bacterial overgrowth, carbohydrate malabsorption and specific nutrient malabsorption (e.g. for iron or vitamins) and protein-losing enteropathy are presented with obligatory and optional tests as used in the clinical setting.
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Affiliation(s)
- Jörg-Dieter Schulzke
- Department of Gastroenterology, Infectiology, and Rheumatology, Hindenburgdamm 30, 12203 Berlin, Germany.
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Jabbour SA, Goldstein BJ. Sodium glucose co-transporter 2 inhibitors: blocking renal tubular reabsorption of glucose to improve glycaemic control in patients with diabetes. Int J Clin Pract 2008; 62:1279-84. [PMID: 18705823 DOI: 10.1111/j.1742-1241.2008.01829.x] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The kidney plays a central role in the regulation of plasma glucose levels, although until recently this has not been widely appreciated or considered a target for therapeutic intervention. The sodium glucose co-transporter type 2 (SGLT2) located in the plasma membrane of cells lining the proximal tubule mediates the majority of renal glucose reabsorption from the tubular fluid, which normally prevents the loss of glucose in the urine. Competitive inhibitors of SGLT2 that provoke the renal excretion of glucose have been discovered, thereby providing a unique mechanism to potentially lower the elevated blood glucose levels in patients with diabetes. OBJECTIVE To explore the physiology of SGLT2 action and discuss several SGLT2 inhibitors that have entered early clinical development. METHODS All publicly available data were identified by searching the internet for 'SGLT2' and 'SGLT2 inhibitor' through 1 November 2007. Published articles, press releases and abstracts presented at national and international meetings were considered. RESULTS/CONCLUSION Sodium glucose co-transporter type 2 inhibition is a novel treatment option for diabetes, which has been studied in preclinical models and a few potent and selective SGLT2 inhibitors have been reported and are currently in clinical development. These agents appear to be safe and generally well tolerated, and will potentially be a beneficial addition to the growing battery of oral antihyperglycaemic agents.
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Affiliation(s)
- S A Jabbour
- Division of Endocrinology, Diabetes & Metabolic Diseases, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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Abstract
Secondary active glucose transport occurs by at least four members of the SLC5 gene family. This review considers the structure and function of two premier members, SGLT1 and SGLT2, and their role in intestinal glucose absorption and renal glucose reabsorption. Genetics disorders of SGLTs include Glucose-Galactose Malabsorption, and Familial Renal Glucosuria. SGLT1 plays a central role in Oral Rehydration Therapy used so effectively to treat secretory diarrhoea such as cholera. Increasing attention is being focused on SGLTs as drug targets for the therapy of diabetes.
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Affiliation(s)
- E M Wright
- Department of Physiology, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1751, USA.
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Gagnon DG, Bissonnette P, Lapointe JY. Identification of a disulfide bridge linking the fourth and the seventh extracellular loops of the Na+/glucose cotransporter. ACTA ACUST UNITED AC 2006; 127:145-58. [PMID: 16446504 PMCID: PMC2151483 DOI: 10.1085/jgp.200509439] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Na+/glucose cotransporter (SGLT1) is an archetype for the SLC5 family, which is comprised of Na+-coupled transporters for sugars, myo-inositol, choline, and organic anions. Application of the reducing agent dithriothreitol (DTT, 10 mM) to oocytes expressing human SGLT1 affects the protein's presteady-state currents. Integration of these currents at different membrane potentials (Vm) produces a Q-V curve, whose form was shifted by +25 mV due to DTT. The role of the 15 endogenous cysteine residues was investigated by expressing SGLT1 constructs, each bearing a single mutation for an individual cysteine, in Xenopus oocytes, using two-microelectrode voltage-clamp electrophysiology and fluorescent labeling. 12 of the 15 mutants were functional and could be separated into three distinct groups based on the effect of the mutation on the Q-V curve: four mutants did not perturb the transferred charge, six mutants shifted the Q-V curve towards negative potentials, and two mutants (C255A and C511A) produced a shift in the positive direction that was identical to the shift produced by DTT on the wild-type (wt) SGLT1. The double mutant C255,511A confirms that the effects of each single mutant on the Q-V curve were not additive. With respect to wt SGLT1, the apparent affinities for α-methylglucose (αMG) were increased in a similar manner for the single mutants C255A and C511A, the double mutant C255,511A as well as for wt SGLT1 treated with DTT. When exposed to a maleimide-based fluorescent probe, wt SGLT1 was not significantly labeled but mutants C255A and C511A could be clearly labeled, indicating an accessible cysteine residue. These residues are presumed to be C511 and C255, respectively, as the double mutant C255,511A could not be labeled. These results strongly support the hypothesis that C255 and C511 form a disulfide bridge in human SGLT1 and that this disulfide bridge is involved in the conformational change of the free carrier.
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Abstract
Carbohydrates are an important component of the diet. The carbohydrates that we ingest range from simple monosaccharides (glucose, fructose and galactose) to disaccharides (lactose, sucrose) to complex polysaccharides. Most carbohydrates are digested by salivary and pancreatic amylases, and are further broken down into monosaccharides by enzymes in the brush border membrane (BBM) of enterocytes. For example, lactase-phloridzin hydrolase and sucrase-isomaltase are two disaccharidases involved in the hydrolysis of nutritionally important disaccharides. Once monosaccharides are presented to the BBM, mature enterocytes expressing nutrient transporters transport the sugars into the enterocytes. This paper reviews the early studies that contributed to the development of a working model of intestinal sugar transport, and details the recent advances made in understanding the process by which sugars are absorbed in the intestine.
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Affiliation(s)
- Laurie A Drozdowski
- Division of Gastroenterology, Department of Medicine, University of Alberta, 5150 Dentistry Pharmacy Building, Edmonton, Alberta T6G 2N8, Canada.
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Kobayashi M, Saitoh H, Yamaguchi M, Saito T, Fujita H, Suno M, Matsubara K, Aungst BJ. Relationship between loperamide-induced sedative effect and digoxin pharmacokinetics in healthy Japanese subjects. Pharm Res 2005; 22:413-8. [PMID: 15835747 DOI: 10.1007/s11095-004-1879-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
PURPOSE Loperamide-induced suppressive effects on central nervous system closely relate to a lack of or decline in the P-glycoprotein (P-gp) function. The aim of this study was to determine the loperamide-induced sedative effect quantitatively and to investigate possible alterations in the pharmacokinetics of digoxin, a substrate for P-gp, in Japanese subjects. METHODS Loperamide hydrochloride (2 mg) was administered orally to 26 subjects and the critical flicker-fusion frequency threshold (CFF) values were measured every 30 min separately by portable instrument. Further, digoxin (0.25 mg) was administered to 8 subjects, and the plasma concentration was determined. RESULTS In five subjects who complained of drowsiness, the CFF values more remarkably decreased compared with those in the other subjects. The Tmax and mean residence time (MRT) values of digoxin pharmacokinetics in four subjects with drowsiness were significantly lower and Cmax was higher than those in four subjects with marginal effect. Moreover, there were good correlations between the CFF value-time profile and the Cmax, Tmax, and MRT of digoxin. CONCLUSIONS The determination of the CFF value after oral administration of loperamide will be useful for evaluating varied P-gp function and for anticipating individual variations in the disposition of P-gp substrates in humans.
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Affiliation(s)
- Michiya Kobayashi
- Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido, Japan
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Katz JP, Perreault N, Goldstein BG, Chao HH, Ferraris RP, Kaestner KH. Foxl1 null mice have abnormal intestinal epithelia, postnatal growth retardation, and defective intestinal glucose uptake. Am J Physiol Gastrointest Liver Physiol 2004; 287:G856-64. [PMID: 15155178 DOI: 10.1152/ajpgi.00136.2004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mice lacking the mesenchymal winged helix transcription factor Foxl1 exhibit markedly abnormal small intestinal epithelia and postnatal growth retardation. We investigated whether defects in intestinal nutrient uptake and specific transport processes exist in mice homozygous for a Foxl1 null allele (Foxl1-/-). Foxl1-/- mice and controls on a defined genetic background were weighed regularly and killed at 2, 4, and 12 wk of age. Intestinal uptake studies, quantitative real-time PCR, RNase protection assays, and Western blot analyses were performed. Foxl1-/- mice have dysmorphic small intestinal epithelia and postnatal growth retardation. Foxl1-/- mice demonstrate decreased small intestinal uptake of D-glucose in all age groups studied. Intestinal uptake of D-fructose and two amino acids, L-proline and L-leucine, is not altered. Consistent with these findings, Foxl1-/- mice show decreased levels of the intestinal D-glucose transporter SGLT1. Expression of sucrase-isomaltase, lactase, GLUT2, and Na+-K+ ATPase are not changed. Foxl1-/- mice demonstrate markedly abnormal intestinal epithelia, postnatal growth retardation, and decreased intestinal uptake of D-glucose. The specific effect of Foxl1 on intestinal d-glucose uptake is due to decreased production of SGLT1 protein in the small intestine. Thus we identified, for the first time, a link between a mesenchymal factor, Foxl1, and the regulation of a specific epithelial transport process.
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Affiliation(s)
- Jonathan P Katz
- Dept. of Genetics, Univ. of Pennsylvania School of Medicine, 415 Curie Blvd., Philadelphia, PA 19104-6145, USA
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39
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Suketa Y. [Fundamental and applied studies on transport and metabolism of electrolytes and glucose--aim to contact with molecular biology]. YAKUGAKU ZASSHI 2002; 122:507-25. [PMID: 12187767 DOI: 10.1248/yakushi.122.507] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The authors' research focuses on polyuria, natriuresis, glucosuria, glycemia, and renal calcification in occupational lead poisoning and endemic fluorosis. Changes in electrolyte mobilization and in glucose metabolism and transport following the administration of lead compounds or fluoride were examined to elucidate these mechanisms. The results suggest fundamental approaches to the mechanism of aging and life style diseases. Our results show that: 1) Natriuresis and polyuria in lead poisoning and fluorosis are due to a decrease in renal Na/K-ATPase activity; 2) Renal calcification in fluorosis is due to stimulation of parathyroid function and activation of the renal phosphatidylinositol cascade; 3) Glycemia in fluorosis is due to elevation of renal and hepatic glucose-6-phosphatase activities; 4) Glusosuria in fluorosis is due to decreased renal Na/K-ATPase activity (but fluoride administered directly did not damage the renal Na/glucose cotransporter (SGLT); 5) Renal calcification in fluorosis is due to stimulation of parathyroid function; and 6) The decrease in renal Na/K-ATPase and SGLT activities with aging and hypertension is due to a decrease in phosphorylation activity by protein kinase C (PKC) etc. (decrease in PKC productivity with aging and hypertension).
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Affiliation(s)
- Yasunobu Suketa
- University of Shizuoka School of Pharmaceutical Sciences, 52-1 Yada, Shizuoka 422-8526, Japan.
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40
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Abstract
The Na(+)-dependent glucose transporter SGLT1 and the facilitated fructose transporter GLUT5 absorb sugars from the intestinal lumen across the brush-border membrane into the cells. The activity of these transport systems is known to be regulated primarily by diet and development. The cloning of these transporters has led to a surge of studies on cellular mechanisms regulating intestinal sugar transport. However, the small intestine can be a difficult organ to study, because its cells are continuously differentiating along the villus, and because the function of absorptive cells depends on both their state of maturity and their location along the villus axis. In this review, I describe the typical patterns of regulation of transport activity by dietary carbohydrate, Na(+) and fibre, how these patterns are influenced by circadian rhythms, and how they vary in different species and during development. I then describe the molecular mechanisms underlying these regulatory patterns. The expression of these transporters is tightly linked to the villus architecture; hence, I also review the regulatory processes occurring along the crypt-villus axis. Regulation of glucose transport by diet may involve increased transcription of SGLT1 mainly in crypt cells. As cells migrate to the villus, the mRNA is degraded, and transporter proteins are then inserted into the membrane, leading to increases in glucose transport about a day after an increase in carbohydrate levels. In the SGLT1 model, transport activity in villus cells cannot be modulated by diet. In contrast, GLUT5 regulation by the diet seems to involve de novo synthesis of GLUT5 mRNA synthesis and protein in cells lining the villus, leading to increases in fructose transport a few hours after consumption of diets containing fructose. In the GLUT5 model, transport activity can be reprogrammed in mature enterocytes lining the villus column. Innovative experimental approaches are needed to increase our understanding of sugar transport regulation in the small intestine. I close by suggesting specific areas of research that may yield important information about this interesting, but difficult, topic.
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41
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Abstract
The Na(+)-dependent glucose transporter SGLT1 and the facilitated fructose transporter GLUT5 absorb sugars from the intestinal lumen across the brush-border membrane into the cells. The activity of these transport systems is known to be regulated primarily by diet and development. The cloning of these transporters has led to a surge of studies on cellular mechanisms regulating intestinal sugar transport. However, the small intestine can be a difficult organ to study, because its cells are continuously differentiating along the villus, and because the function of absorptive cells depends on both their state of maturity and their location along the villus axis. In this review, I describe the typical patterns of regulation of transport activity by dietary carbohydrate, Na(+) and fibre, how these patterns are influenced by circadian rhythms, and how they vary in different species and during development. I then describe the molecular mechanisms underlying these regulatory patterns. The expression of these transporters is tightly linked to the villus architecture; hence, I also review the regulatory processes occurring along the crypt-villus axis. Regulation of glucose transport by diet may involve increased transcription of SGLT1 mainly in crypt cells. As cells migrate to the villus, the mRNA is degraded, and transporter proteins are then inserted into the membrane, leading to increases in glucose transport about a day after an increase in carbohydrate levels. In the SGLT1 model, transport activity in villus cells cannot be modulated by diet. In contrast, GLUT5 regulation by the diet seems to involve de novo synthesis of GLUT5 mRNA synthesis and protein in cells lining the villus, leading to increases in fructose transport a few hours after consumption of diets containing fructose. In the GLUT5 model, transport activity can be reprogrammed in mature enterocytes lining the villus column. Innovative experimental approaches are needed to increase our understanding of sugar transport regulation in the small intestine. I close by suggesting specific areas of research that may yield important information about this interesting, but difficult, topic.
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Affiliation(s)
- R P Ferraris
- Department of Pharmacology and Physiology, UMDNJ-New Jersey Medical School, 185 S. Orange Avenue, Newark, NJ 07103-2714, USA.
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42
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Abstract
In humans, the kidneys filter approximately 180 g of D-glucose from plasma each day, and this is normally reabsorbed in the proximal tubules. Although the mechanism of reabsorption is well understood, Na(+)-glucose cotransport across the brush-border membrane and facilitated diffusion across the basolateral membrane, questions remain about the identity of the genes responsible for cotransport across the brush border. Genetic studies suggest that two different genes regulate Na(+)-glucose cotransport, and there is evidence from animal studies to suggest that the major bulk of sugar is reabsorbed in the convoluted proximal tubule by a low-affinity, high-capacity transporter and that the remainder is absorbed in the straight proximal tubule by a high-affinity, low-capacity transporter. There are at least three different candidates for these human renal Na(+)-glucose cotransporters. This review will focus on the structure-function relationships of these three transporters, SGLT1, SGLT2, and SGLT3.
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Affiliation(s)
- E M Wright
- Department of Physiology, University of California Los Angeles School of Medicine, Los Angeles, California 90095-1751, USA.
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Affiliation(s)
- L Reuss
- Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77555-0641, USA.
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Halaihel N, Liévin V, Alvarado F, Vasseur M. Rotavirus infection impairs intestinal brush-border membrane Na(+)-solute cotransport activities in young rabbits. Am J Physiol Gastrointest Liver Physiol 2000; 279:G587-96. [PMID: 10960359 DOI: 10.1152/ajpgi.2000.279.3.g587] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The mechanism of rotavirus diarrhea was investigated by infecting young, specific pathogen-free, New Zealand rabbits with a lapine rotavirus, strain La/RR510. With 4-wk-old animals, virus shedding into the intestinal lumen peaked at 72 h postinfection (hpi), and a mild, watery diarrhea appeared at 124 hpi. No intestinal lesions were seen up to 144 hpi, indicating that diarrhea does not follow mucosal damage but can precede it, as if cell dysfunction were the cause, not the consequence, of the histological lesions. Kinetic analyses with brush-border membrane vesicles isolated from infected rabbits revealed strong inhibition of both Na(+)-D-glucose (SGLT1) and Na(+)-L-leucine symport activities. For both symporters, only maximum velocity decreased with time. The density of phlorizin-binding sites and SGLT1 protein antigen in the membrane remained unaffected, indicating that the virus effect on this symporter is direct. Because SGLT1 supports water reabsorption under physiological conditions, the mechanism of rotavirus diarrhea may involve a generalized inhibition of Na(+)-solute symport systems, hence, of water reabsorption. Massive water loss through the intestine may eventually overwhelm the capacity of the organ for water reabsorption, thereby helping the diarrhea to get established.
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Affiliation(s)
- N Halaihel
- Institut National de la Santé et de la Recherche Médicale, Unité 510, Faculté de Pharmacie, Université de Paris XI, 92296 Châtenay-Malabry, France
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