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Poulsen SB, Murali SK, Thomas L, Assmus A, Rosenbæk LL, Nielsen R, Dimke H, Rieg T, Fenton RA. Genetic deletion of the kidney sodium/proton exchanger-3 (NHE3) does not alter calcium and phosphate balance due to compensatory responses. Kidney Int 2024:S0085-2538(24)00533-7. [PMID: 39089578 DOI: 10.1016/j.kint.2024.07.013] [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: 07/05/2022] [Revised: 06/10/2024] [Accepted: 07/02/2024] [Indexed: 08/04/2024]
Abstract
The sodium/proton exchanger-3 (NHE3) plays a major role in acid-base and extracellular volume regulation and is also implicated in calcium homeostasis. As calcium and phosphate balances are closely linked, we hypothesized that there was a functional link between kidney NHE3 activity, calcium, and phosphate balance. Therefore, we examined calcium and phosphate homeostasis in kidney tubule-specific NHE3 knockout mice (NHE3loxloxPax8 mice). Compared to controls, these knockout mice were normocalcemic with no significant difference in urinary calcium excretion or parathyroid hormone levels. Thiazide-induced hypocalciuria was less pronounced in the knockout mice, in line with impaired proximal tubule calcium transport. Knockout mice had greater furosemide-induced calciuresis and distal tubule calcium transport pathways were enhanced. Despite lower levels of the sodium/phosphate cotransporters (NaPi)-2a and -2c, knockout mice had normal plasma phosphate, sodium-dependent 32Phosphate uptake in proximal tubule membrane vesicles and urinary phosphate excretion. Intestinal phosphate uptake was unchanged. Low dietary phosphate reduced parathyroid hormone levels and increased NaPi-2a and -2c abundances in both genotypes, but NaPi-2c levels remained lower in the knockout mice. Gene expression profiling suggested proximal tubule remodeling in the knockout mice. Acutely, indirect NHE3 inhibition using the SGLT2 inhibitor empagliflozin did not affect urinary calcium and phosphate excretion. No differences in femoral bone density or architecture were detectable in the knockout mice. Thus, a role for kidney NHE3 in calcium homeostasis can be unraveled by diuretics, but NHE3 deletion in the kidneys has no major effects on overall calcium and phosphate homeostasis due, at least in part, to compensating mechanisms.
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Affiliation(s)
- Søren B Poulsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Sathish K Murali
- Department of Biomedicine, Aarhus University, Aarhus, Denmark; Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Linto Thomas
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida, USA
| | - Adrienne Assmus
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Lena L Rosenbæk
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Rikke Nielsen
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Henrik Dimke
- Department of Cardiovascular and Renal Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark; Department of Nephrology, Odense University Hospital, Odense, Denmark
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida, USA; James A. Haley Veterans' Hospital, Tampa, Florida, USA.
| | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
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2
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Hill Gallant KM, Sprague SM, Rosenbaum DP, Spiegel DM, Kozuka K, Edelstein S, Chertow GM. Tenapanor: A Phosphate Absorption Inhibitor for the Management of Hyperphosphatemia in Patients With Kidney Failure. J Ren Nutr 2024:S1051-2276(24)00156-0. [PMID: 38992521 DOI: 10.1053/j.jrn.2024.07.003] [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: 04/16/2024] [Accepted: 07/01/2024] [Indexed: 07/13/2024] Open
Abstract
Because of increased risks of cardiovascular disease and death, patients with hyperphosphatemia receiving maintenance dialysis are advised to limit phosphorus consumption and are prescribed phosphate binders in an effort to better control serum phosphate concentrations. Because of large pill size, pill burden, and tolerability issues, phosphate binder adherence is relatively poor. On ingestion, phosphate is absorbed from the intestine via transcellular or paracellular transport. Data show that inhibiting sodium-hydrogen exchanger 3 modulates paracellular phosphate absorption (the predominant pathway in humans). Tenapanor is a first-in-class, minimally absorbed, phosphate absorption inhibitor that selectively inhibits sodium-hydrogen exchanger 3, with a mechanism distinct from, and complementary to, that of phosphate binders. In phase 3 and postregistrational studies, tenapanor conferred statistically significant and clinically meaningful reductions in serum phosphate in patients receiving maintenance dialysis with hyperphosphatemia. Here, we review the available preclinical and clinical data on the effects of tenapanor on controlling intestinal phosphate absorption.
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Affiliation(s)
- Kathleen M Hill Gallant
- Associate Professor, Department of Food Science and Nutrition, University of Minnesota, Saint Paul, Minnesota.
| | - Stuart M Sprague
- Clinical Professor of Medicine, Endeavor Health, University of Chicago, Evanston, Illinois
| | | | - David M Spiegel
- Vice President, Nephrology, Ardelyx, Inc., Waltham, Massachusetts
| | - Kenji Kozuka
- Director, Preclinical Research and Nonclinical Development, Ardelyx, Inc., Fremont, California
| | - Susan Edelstein
- Senior Vice President, Clinical Research, Ardelyx, Inc., Waltham, Massachusetts
| | - Glenn M Chertow
- Professor of Medicine - Nephrology, Departments of Medicine and Epidemiology and Population Health, Stanford University, Palo Alto, California
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3
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Chrysant SG. The Interaction of Kidneys and Gut in Development of Salt-Sensitive Hypertension. Cardiol Rev 2024; 32:356-361. [PMID: 37273192 DOI: 10.1097/crd.0000000000000518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The incidence of salt-sensitive hypertension is quite common and varies between 30-60% in hypertensive patients. Regarding the causal role of high salt intake in the development of salt-sensitive hypertension, recent evidence has demonstrated that the gut through its microbiota plays a significant role in its genesis. Besides the gut, the kidneys also play important role in salt-sensitive hypertension and there is clinical and experimental evidence of an interrelationship between the gut and the kidneys in the development of salt-sensitive hypertension through the so-called "gastro-renal axis." The gut besides being an absorptive organ, it is also a hormonal secretory organ involving the secretion of gastrin, dopamine, norepinephrine, angiotensin, and aldosterone which through their action with the kidneys are involved in the development of salt-sensitive hypertension. In addition, the kidneys exert a protective role against the development of hypertension through the secretion of prostaglandins and their vasodilatory action. To assess the current evidence on the role of high salt intake and the interplay of the gut and kidneys in its development, a Medline search of the English literature was contacted between 2012 and 2022, and 46 pertinent papers were selected. These papers together with collateral literature will be discussed in this review.
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Affiliation(s)
- Steven G Chrysant
- From the University of Oklahoma Health Sciences Center, Oklahoma City, OK
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4
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Power DA, Hemetsberger R, Farhan S, Abdel-Wahab M, Yasumura K, Kini A, Sharma SK. Calcified coronary lesions: Imaging, prognosis, preparation and treatment state of the art review. Prog Cardiovasc Dis 2024:S0033-0620(24)00095-1. [PMID: 38925256 DOI: 10.1016/j.pcad.2024.06.007] [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] [Received: 06/23/2024] [Accepted: 06/23/2024] [Indexed: 06/28/2024]
Abstract
Calcific coronary artery stenosis is a complex disease associated with adverse outcomes and suboptimal percutaneous treatment. Calcium plaque modification has emerged as a key strategy to tackle the issues that accompany calcific stenosis - namely reduced device deliverability, unpredictable lesion characteristics, and difficult dilatation. Atherectomy has traditionally been the treatment modality of choice for heavily calcified coronary stenoses. Contemporary technologies have emerged to aid with planning, preparation, and treatment of calcified coronary stenosis in an attempt to improve procedural success and long-term outcomes. In this State Of The Art Review, we synthesize the body of data surrounding the diagnosis, imaging, and treatment of calcific coronary disease, with a focus on i) intravascular imaging, ii) calcific lesion preparation, iii) treatment modalities including atherectomy, and iv) updated treatment algorithms for the management of calcified coronary stenosis.
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Affiliation(s)
- David A Power
- The Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York City, NY, United States of America
| | - Rayyan Hemetsberger
- Department of Cardiology, Internal Medicine II, Medical University of Vienna, Austria
| | - Serdar Farhan
- The Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York City, NY, United States of America
| | - Mohamed Abdel-Wahab
- Department of Internal Medicine/Cardiology, Heart Center Leipzig at University of Leipzig, Leipzig, Germany
| | - Keisuke Yasumura
- The Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York City, NY, United States of America
| | - Annapoorna Kini
- The Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York City, NY, United States of America
| | - Samin K Sharma
- The Zena and Michael A. Wiener Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York City, NY, United States of America.
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Chrysant SG. The role of gut microbiota in the development of salt-sensitive hypertension and the possible preventive effect of exercise. Expert Rev Cardiovasc Ther 2024; 22:265-271. [PMID: 38823009 DOI: 10.1080/14779072.2024.2364031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 05/31/2024] [Indexed: 06/03/2024]
Abstract
INTRODUCTION The aim of the present study is to analyze the data indicating an association between high salt intake and the gastrointestinal microbiota in the development of salt-sensitive hypertension in animals and men. It is also, to discuss the preventive effects of exercise on gut-induced hypertension by favorably modifying the composition of gut microbiota. AREAS COVERED Salt sensitivity is quite common, accounting for 30%-60% in hypertensive subjects. Recently, a novel cause for salt-sensitive hypertension has been discovered through the action of gut microbiota by the secretion of several hormones and the action of short chain fatty acids (SCFAs). In addition, recent studies indicate that exercise might favorably modify the adverse effects of gut microbiota regarding their effects on BP. To identify the role of gut microbiota on the incidence of hypertension and CVD and the beneficial effect of exercise, a Medline search of the English literature was conducted between 2018 and 2023 and 42 pertinent papers were selected. EXPERT OPINION The analysis of data from the selected papers disclosed that the gut microbiota contribute significantly to the development of salt-sensitive hypertension and that exercise modifies their gut composition and ameliorates their adverse effects on BP.
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Affiliation(s)
- Steven G Chrysant
- Cardiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Ito N, Hidaka N, Kato H. The pathophysiology of hypophosphatemia. Best Pract Res Clin Endocrinol Metab 2024; 38:101851. [PMID: 38087658 DOI: 10.1016/j.beem.2023.101851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
After identification of fibroblast growth factor (FGF) 23 as the pivotal regulator of chronic serum inorganic phosphate (Pi) levels, the etiology of disorders causing hypophosphatemic rickets/osteomalacia has been clarified, and measurement of intact FGF23 serves as a potent tool for differential diagnosis of chronic hypophosphatemia. Additionally, measurement of bone-specific alkaline phosphatase (BAP) is recommended to differentiate acute and subacute hypophosphatemia from chronic hypophosphatemia. This article divides the etiology of chronic hypophosphatemia into 4 groups: A. FGF23 related, B. primary tubular dysfunction, C. disturbance of vitamin D metabolism, and D. parathyroid hormone 1 receptor (PTH1R) mediated. Each group is further divided into its inherited form and acquired form. Topics for each group are described, including "ectopic FGF23 syndrome," "alcohol consumption-induced FGF23-related hypophosphatemia," "anti-mitochondrial antibody associated hypophosphatemia," and "vitamin D-dependent rickets type 3." Finally, a flowchart for differential diagnosis of chronic hypophosphatemia is introduced.
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Affiliation(s)
- Nobuaki Ito
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo, Japan; Osteoporosis Center, The University of Tokyo Hospital, Tokyo, Japan.
| | - Naoko Hidaka
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo, Japan; Osteoporosis Center, The University of Tokyo Hospital, Tokyo, Japan.
| | - Hajime Kato
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo, Japan; Osteoporosis Center, The University of Tokyo Hospital, Tokyo, Japan.
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Nakayama M, Kobayashi S, Kusakabe M, Ohara M, Nakanishi K, Akizawa T, Fukagawa M. Tenapanor for peritoneal dialysis patients with hyperphosphatemia: a phase 3 trial. Clin Exp Nephrol 2024; 28:153-164. [PMID: 37910313 PMCID: PMC10808471 DOI: 10.1007/s10157-023-02406-1] [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: 04/03/2023] [Accepted: 09/10/2023] [Indexed: 11/03/2023]
Abstract
BACKGROUND Tenapanor is a novel selective inhibitor of intestinal sodium/hydrogen exchanger 3 transporter. This is the first trial to assess the efficacy and safety of tenapanor in Japanese patients with hyperphosphatemia who are undergoing peritoneal dialysis. METHODS This phase 3, open-label, multicenter, single-arm clinical trial targeted patients whose serum phosphorus was within 3.5-7.0 mg/dL with phosphate binders at screening. After phosphate binder washout, tenapanor was orally administered twice-daily, stepwise from 5 to 30 mg/dose for 16 weeks. The primary endpoint, mean change in serum phosphorus level, was evaluated at week 8. The 16-week treatment period was completed with tenapanor alone, and only one phosphate binder type was allowed for combined use after the primary endpoint. RESULTS Of the 54 patients enrolled, 34 completed the study. At week 8, the primary endpoint, mean change in serum phosphorus level (last observation carried forward), was - 1.18 mg/dL (95% confidence interval: - 1.54, - 0.81 mg/dL) with tenapanor. From a baseline value of 7.65 mg/dL, serum phosphorus decreased to 6.14 and 5.44 mg/dL at weeks 8 and 16, respectively, and 46.3% and 76.5% of patients achieved serum phosphorus within 3.5-6.0 mg/dL at week 8 and week 16, respectively. The most common adverse event, diarrhea, occurred in 74.1% of patients; the severity of diarrhea was mild or moderate. Thus, the discontinuation percentage due to diarrhea was low at 5.6%. CONCLUSIONS Administration of tenapanor resulted in a sufficient reduction in serum phosphorus level at week 8 and was considered safe and tolerable. TRIAL REGISTRATION NCT04766385.
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Affiliation(s)
- Masaaki Nakayama
- Kidney Center, St. Luke's International Hospital, 9-1 Akashi-cho, Chuo-ku, Tokyo, 104-8560, Japan.
| | | | | | - Meiko Ohara
- R&D Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | | | - Tadao Akizawa
- Division of Nephrology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
| | - Masafumi Fukagawa
- Division of Nephrology, Endocrinology, and Metabolism, Department of Internal Medicine, Tokai University School of Medicine, Kanagawa, Japan
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8
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Wang X, Yu X, Gavardinas K, Dey A, Zhang HY, Porter G, Porras L, Yu L, Guo H, Reidy CA, Haas JV, Xu Y, Kowala MC, Jadhav PK, Wetterau JR. Effect of an NHE3 inhibitor in combination with an NPT2b inhibitor on gastrointestinal phosphate absorption in Rodent models. PLoS One 2024; 19:e0292091. [PMID: 38277356 PMCID: PMC10817170 DOI: 10.1371/journal.pone.0292091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 09/12/2023] [Indexed: 01/28/2024] Open
Abstract
Many of the pathological consequences of chronic kidney disease can be attributed to an elevation in serum phosphate levels. Current therapies focused on decreasing intestinal phosphate absorption to treat hyperphosphatemia are inadequate. The most effective therapeutic strategy may be to target multiple absorptive pathways. In this study, the ability of a novel inhibitor of the intestinal sodium hydrogen exchanger 3 (NHE3), LY3304000, which inhibits paracellular, diffusional uptake of phosphate, to work in combination with an inhibitor of the active transporter, sodium dependent phosphate cotransporter 2b (NPT2b), LY3358966, was explored. LY3304000 modestly inhibited the acute uptake of phosphate into plasma of rats, while surprisingly, it doubled the rate of phosphate uptake in mice, an animal model dominated by NPT2b mediated acute phosphate uptake. In rats, LY3004000 and LY3358966 work in concert to inhibit acute phosphate uptake. On top of LY3358966, LY3304000 further decreased the acute uptake of phosphate into plasma. Studies measuring the recovery of radiolabeled phosphate in the intestine demonstrated LY3304000 and LY3358966 synergistically inhibited the absorption of phosphate in rats. We hypothesize the synergism is because the NHE3 inhibitor, LY3304000, has two opposing effects on intestinal phosphate absorption in rats, first it decreases diffusion mediated paracellular phosphate absorption, while second, it simultaneously increases phosphate absorption through the NPT2b pathway. NHE3 inhibition decreases proton export from enterocytes and raises the cell surface pH. In vitro, NPT2b mediated phosphate transport is increased at higher pHs. The increased NPT2b mediated transport induced by NHE3 inhibition is masked in rats which have relatively low levels of NPT2b mediated phosphate transport, by the more robust inhibition of diffusion mediated phosphate absorption. Thus, the inhibition of NPT2b mediated phosphate transport in rats in the presence of NHE3 inhibition has an effect that exceeds its effect in the absence of NHE3 inhibition, leading to the observed synergism on phosphate absorption between NPT2b and NHE3 inhibition.
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Affiliation(s)
- Xiaojun Wang
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Xiaohong Yu
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Kostas Gavardinas
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Asim Dey
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Hong Y. Zhang
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Gina Porter
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Leah Porras
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Lan Yu
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Haihong Guo
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Charles A. Reidy
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Joseph V. Haas
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Yanping Xu
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Mark C. Kowala
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - Prabhakar K. Jadhav
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
| | - John R. Wetterau
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, United States of America
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9
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Abstract
Inorganic phosphate (Pi) is an essential component of many biologically important molecules such as DNA, RNA, ATP, phospholipids, or apatite. It is required for intracellular phosphorylation signaling events and acts as pH buffer in intra- and extracellular compartments. Intestinal absorption, uptake into cells, and renal reabsorption depend on a set of different phosphate transporters from the SLC20 (PiT transporters) and SLC34 (NaPi transporters) gene families. The physiological relevance of these transporters is evident from rare monogenic disorders in humans affecting SLC20A2 (Fahr's disease, basal ganglia calcification), SLC34A1 (idiopathic infantile hypercalcemia), SLC34A2 (pulmonary alveolar microlithiasis), and SLC34A3 (hereditary hypophosphatemic rickets with hypercalciuria). SLC34 transporters are inhibited by millimolar concentrations of phosphonoformic acid or arsenate while SLC20 are relatively resistant to these compounds. More recently, a series of more specific and potent drugs have been developed to target SLC34A2 to reduce intestinal Pi absorption and to inhibit SLC34A1 and/or SLC34A3 to increase renal Pi excretion in patients with renal disease and incipient hyperphosphatemia. Also, SLC20 inhibitors have been developed with the same intention. Some of these substances are currently undergoing preclinical and clinical testing. Tenapanor, a non-absorbable Na+/H+-exchanger isoform 3 inhibitor, reduces intestinal Pi absorption likely by indirectly acting on the paracellular pathway for Pi and has been tested in several phase III trials for reducing Pi overload in patients with renal insufficiency and dialysis.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.
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10
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Fukagawa M, Urano N, Ikejiri K, Kinoshita J, Nakanishi K, Akizawa T. Tenapanor for the Treatment of Hyperphosphatemia in Japanese Hemodialysis Patients: A Randomized Phase 3 Monotherapy Study With an Up-titration Regimen. Am J Kidney Dis 2023; 82:635-637. [PMID: 37330134 DOI: 10.1053/j.ajkd.2023.03.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 03/28/2023] [Indexed: 06/19/2023]
Affiliation(s)
- Masafumi Fukagawa
- Division of Nephrology, Endocrinology, and Metabolism, Department of Internal Medicine, Tokai University School of Medicine, Kanagawa, Japan.
| | | | | | | | | | - Tadao Akizawa
- Division of Nephrology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
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Nitta K, Itoyama S, Ikejiri K, Kinoshita J, Nakanishi K, Fukagawa M, Akizawa T. Randomized Study of Tenapanor Added to Phosphate Binders for Patients With Refractory Hyperphosphatemia. Kidney Int Rep 2023; 8:2243-2253. [PMID: 38025211 PMCID: PMC10658421 DOI: 10.1016/j.ekir.2023.08.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 07/26/2023] [Accepted: 08/07/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Serum phosphorus management is important for patients with chronic kidney disease on dialysis to reduce the risk of hyperparathyroidism and ectopic vascular calcification. Phosphate binders (PBs) control serum phosphorus levels; however, some patients do not achieve adequate control with existing PBs. The similar mechanisms of action of each PB may limit their ability to lower serum phosphorus levels. Therefore, drugs with novel mechanisms of action that can be added to existing PBs to further lower serum phosphorus levels are desired. Tenapanor, a novel selective inhibitor of intestinal sodium/hydrogen exchanger 3 transporters, decreases passive phosphate absorption in the intestine, thereby decreasing serum phosphorus levels. Methods This study evaluated the efficacy and safety of tenapanor treatment with up-titration when added to PBs among Japanese hemodialysis patients with hyperphosphatemia poorly controlled by PBs alone. In total, 169 patients taking PBs whose serum phosphorus level was ≥6.1 and <10.0 mg/dl initiated the 8-week treatment (placebo + PB, n = 85; tenapanor + PB, n = 84). Results The least squares mean change from baseline to week 8 in serum phosphorus level was -0.24 and -2.00 mg/dl in the placebo and tenapanor groups, respectively, with a statistically significant difference between groups (-1.76 mg/dl; P < 0.0001). Diarrhea as a treatment-emergent adverse event (TEAE) occurred in 14.1% and 63.1% of patients in the placebo and tenapanor groups, respectively. All diarrhea events were mild or moderate. Conclusion Tenapanor added to PBs improved serum phosphorus levels that could not previously be controlled by PBs alone, and no new safety concerns were raised.
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Affiliation(s)
- Kosaku Nitta
- Department of Nephrology, Tokyo Women’s Medical University, Tokyo, Japan
| | - Saki Itoyama
- Research and Development Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Kazuaki Ikejiri
- Research and Development Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Jun Kinoshita
- Research and Development Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Kaoru Nakanishi
- Research and Development Division, Kyowa Kirin Co., Ltd., Tokyo, Japan
| | - Masafumi Fukagawa
- Division of Nephrology, Endocrinology, and Metabolism, Department of Internal Medicine, Tokai University School of Medicine, Kanagawa, Japan
| | - Tadao Akizawa
- Division of Nephrology, Department of Medicine, Showa University School of Medicine, Tokyo, Japan
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12
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Cernaro V, Longhitano E, Calabrese V, Casuscelli C, Di Carlo S, Spinella C, Gembillo G, Santoro D. Progress in pharmacotherapy for the treatment of hyperphosphatemia in renal failure. Expert Opin Pharmacother 2023; 24:1737-1746. [PMID: 37527180 DOI: 10.1080/14656566.2023.2243817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 07/26/2023] [Accepted: 07/31/2023] [Indexed: 08/03/2023]
Abstract
INTRODUCTION Among the clinical and metabolic complications of progressive chronic kidney disease (CKD), CKD-mineral bone disorder (CKD-MBD) significantly contributes to morbidity and mortality. While overt and persistent hyperphosphatemia is typical of advanced CKD and requires treatment, other abnormalities of calcium/phosphate metabolism begin to occur since the early stages of the disease. AREAS COVERED We searched on the PubMed database, without restrictions for language or time range, for randomized clinical trials and meta-analyses investigating phosphate-lowering therapies. The various phosphate binders show different safety profiles and diverse effects on calcium/phosphate metabolism and vascular calcification. The in-depth knowledge of the characteristics of these drugs is crucial to ensure adequate treatment to CKD patients. EXPERT OPINION A proper control of serum phosphate can be achieved using phosphate binders. These medications may induce side effects. Moreover, data on their impact on clinical outcomes are partly controversial or scarce, especially for the new generation drugs. Hyperphosphatemia favors cardiovascular disease and increases the risk for CKD progression. These effects are partially mediated by fibroblast growth factor 23 (FGF23), a phosphaturic hormone that raises to maintain normal serum phosphate. Since there are no data supporting the use of phosphate-lowering agents when phosphataemia is normal, a key role is played by reducing dietary phosphate intake with the aim to control serum phosphate and the compensatory FGF23 and parathyroid hormone (PTH) increase.
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Affiliation(s)
- Valeria Cernaro
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Elisa Longhitano
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Vincenzo Calabrese
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Chiara Casuscelli
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Silvia Di Carlo
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Claudia Spinella
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Guido Gembillo
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Domenico Santoro
- Unit of Nephrology and Dialysis, Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
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13
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Cil O, Anderson MO, de Souza Goncalves L, Tan JA, Haggie PM, Verkman AS. Small molecule inhibitors of intestinal epithelial anion exchanger SLC26A3 (DRA) with a luminal, extracellular site of action. Eur J Med Chem 2023; 249:115149. [PMID: 36724632 PMCID: PMC10124120 DOI: 10.1016/j.ejmech.2023.115149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 01/13/2023] [Accepted: 01/22/2023] [Indexed: 01/30/2023]
Abstract
The anion exchanger protein SLC26A3 (down-regulated in adenoma, DRA) is expressed in the luminal membrane of intestinal epithelial cells in colon, where it facilitates the absorption of Cl- and oxalate. We previously identified a 4,8-dimethylcoumarin class of SLC26A3 inhibitors that act from the SLC26A3 cytoplasmic surface, and demonstrated their efficacy in mouse models of constipation and hyperoxaluria. Here, screening of 50,000 new compounds and 1740 chemical analogs of active compounds from the primary screen produced five novel classes of SLC26A3-selective inhibitors (1,3-dioxoisoindoline-amides; N-(5-sulfamoyl-1,3,4-thiadiazol-2-yl)acetamides; thiazolo-pyrimidin-5-ones; 3-carboxy-2-phenylbenzofurans and benzoxazin-4-ones) with IC50 down to 100 nM. Kinetic washout and onset of action studies revealed an extracellular site of action for the thiazolo-pyrimidin-5-one and 3-carboxy-2-phenylbenzofuran inhibitors. Molecular docking computations revealed putative binding sites for these inhibitors. In a loperamide model of constipation in mice, orally administered 7-(2-chloro-phenoxymethyl)-3-phenyl-thiazolo [3,2-a]pyrimidin-5-one (3a) significantly increased stool weight, pellet number and water content. SLC26A3 inhibitors with an extracellular site of action offer the possibility of creating non-absorbable, luminally acting inhibitors with minimal systemic exposure following oral administration. Our findings also suggest that inhibitors of related SLC26 anion transporters with an extracellular site of action might be identified for pharmacological modulation of selected epithelial ion transport processes.
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Affiliation(s)
- Onur Cil
- Department of Pediatrics, University of California San Francisco, San Francisco, CA, USA.
| | - Marc O Anderson
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA, USA
| | | | - Joseph-Anthony Tan
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, USA
| | - Peter M Haggie
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, USA
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California San Francisco, San Francisco, CA, USA
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14
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Abstract
Phosphate homeostasis is dependent on the interaction and coordination of four main organ systems: thyroid/parathyroids, gastrointestinal tract, bone and kidneys, and three key hormonal regulators, 1,25-hydroxyvitamin D3, parathyroid hormone and FGF23 with its co- factor klotho. Phosphorus is a critical nutritional element for normal cellular function, but in excess can be toxic to tissues, particularly the vasculature. As phosphate, it also has an important interaction and inter-dependence with calcium and calcium homeostasis sharing some of the same controlling hormones, although this is not covered in our article. We have chosen to provide a current overview of phosphate homeostasis only, focusing on the role of two major organ systems, the gastrointestinal tract and kidneys, and their contribution to the control of phosphate balance. We describe in some detail the mechanisms of intestinal and renal phosphate transport, and compare and contrast their regulation. We also consider a significant example of phosphate imbalance, with phosphate retention, which is chronic kidney disease; why consequent hyperphosphatemia is important, and some of the newer means of managing it.
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Affiliation(s)
- Joanne Marks
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
| | - Robert J Unwin
- Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom; Department of Renal Medicine, University College London, London, United Kingdom.
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15
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Gu J, Shi J, Chen X, Mao J, You H, Chen J. High sodium reduced the expression of PTH1R and Klotho by inhibiting 1,25(OH) 2D 3 synthesis in cultured proximal tubule epithelial cells. ANNALS OF TRANSLATIONAL MEDICINE 2022; 10:506. [PMID: 35928745 PMCID: PMC9347055 DOI: 10.21037/atm-21-5910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/10/2022] [Indexed: 11/06/2022]
Abstract
Background The proximal tubule is the sensing site of sodium and phosphate and the main place for the synthesis and metabolism of 1,25(OH)2D3. We aimed to investigate the effects of high sodium on the synthesis and function of active vitamin D and local phosphate regulation in proximal tubular epithelial cells. Methods Human proximal tubule epithelial (HK-2) cells were treated with different concentrations of sodium/phosphate. The expression of 1α-OHase and 24-OHase was determined. Liquid chromatography/mass spectrometry (LC/MS) and enzyme-linked immunosorbent assay (ELISA) were used to detect the levels of 1,25(OH)2D3. RNA sequencing and bioinformatics analysis was used to probe into the possible pathways. Chromatin samples were immunoprecipitated with antibodies against parathyroid receptor 1 (PTH1R) and Klotho. Results We found that high sodium decreased the expression of 1,25(OH)2D3 by reducing 1α-OHase and 24-OHase, reduced the expression of PTH1R and Klotho, and increased the intracellular calcium concentration. These effects were reversed by sodium phosphate transporter inhibitor, sodium hydrogen transporter inhibitor, and a chelator of the extracellular calcium, whereas enhanced by ouabain. Vitamin D receptor (VDR) agonists significantly increased the recruitment of VDR to the vitamin D response element (VDRE) of PTH1R and Klotho promoter, thus increasing the expression of PTH1R and Klotho. Conclusions High sodium can decrease the synthesis of active vitamin D in the proximal tubules, affect the gene regulation of 1,25(OH)2D3/VDR, and significantly reduce the expression of PTH1R and Klotho. It revealed the influence of a high-sodium diet on mineral metabolism and the core role of vitamin D in kidney mineral metabolism.
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Affiliation(s)
- Jie Gu
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Jialin Shi
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Xujiao Chen
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Jianping Mao
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Huaizhou You
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Jing Chen
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
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16
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Xue J, Thomas L, Murali SK, Levi M, Fenton RA, Dominguez Rieg JA, Rieg T. Enhanced phosphate absorption in intestinal epithelial cell-specific NHE3 knockout mice. Acta Physiol (Oxf) 2022; 234:e13756. [PMID: 34978760 PMCID: PMC9286053 DOI: 10.1111/apha.13756] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 11/16/2021] [Accepted: 01/01/2022] [Indexed: 12/11/2022]
Abstract
Aims The kidneys play a major role in maintaining Pi homeostasis. Patients in later stages of CKD develop hyperphosphatemia. One novel treatment option is tenapanor, an intestinal‐specific NHE3 inhibitor. To gain mechanistic insight into the role of intestinal NHE3 in Pi homeostasis, we studied tamoxifen‐inducible intestinal epithelial cell‐specific NHE3 knockout (NHE3IEC‐KO) mice. Methods Mice underwent dietary Pi challenges, and hormones as well as urinary/plasma Pi were determined. Intestinal 33P uptake studies were conducted in vivo to compare the effects of tenapanor and NHE3IEC‐KO. Ex vivo Pi transport was measured in everted gut sacs and brush border membrane vesicles. Intestinal and renal protein expression of Pi transporters were determined. Results On the control diet, NHE3IEC‐KO mice had similar Pi homeostasis, but a ~25% reduction in FGF23 compared with control mice. Everted gut sacs and brush border membrane vesicles showed enhanced Pi uptake associated with increased Npt2b expression in NHE3IEC‐KO mice. Acute oral Pi loading resulted in higher plasma Pi in NHE3IEC‐KO mice. Tenapanor inhibited intestinal 33P uptake acutely but then led to hyper‐absorption at later time points compared to vehicle. In response to high dietary Pi, plasma Pi and FGF23 increased to higher levels in NHE3IEC‐KO mice which was associated with greater Npt2b expression. Reduced renal Npt2c and a trend for reduced Npt2a expression were unable to correct for higher plasma Pi. Conclusion Intestinal NHE3 has a significant contribution to Pi homeostasis. In contrast to effects described for tenapanor on Pi homeostasis, NHE3IEC‐KO mice show enhanced, rather than reduced, intestinal Pi uptake.
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Affiliation(s)
- Jianxiang Xue
- Department of Molecular Pharmacology and Physiology Morsani College of Medicine University of South Florida Tampa Florida USA
| | - Linto Thomas
- Department of Molecular Pharmacology and Physiology Morsani College of Medicine University of South Florida Tampa Florida USA
| | | | - Moshe Levi
- Department of Biochemistry and Molecular & Cellular Biology Georgetown University Washington District of Columbia USA
| | | | - Jessica A. Dominguez Rieg
- Department of Molecular Pharmacology and Physiology Morsani College of Medicine University of South Florida Tampa Florida USA
- James A. Haley Veterans' Hospital Tampa Florida USA
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology Morsani College of Medicine University of South Florida Tampa Florida USA
- James A. Haley Veterans' Hospital Tampa Florida USA
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17
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Leifheit-Nestler M, Vogt I, Haffner D, Richter B. Phosphate Is a Cardiovascular Toxin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1362:107-134. [DOI: 10.1007/978-3-030-91623-7_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Kovesdy CP, Adebiyi A, Rosenbaum D, Jacobs JW, Quarles LD. Novel Treatments from Inhibition of the Intestinal Sodium-Hydrogen Exchanger 3. Int J Nephrol Renovasc Dis 2021; 14:411-420. [PMID: 34880650 PMCID: PMC8646223 DOI: 10.2147/ijnrd.s334024] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/11/2021] [Indexed: 12/31/2022] Open
Abstract
Plasma membrane sodium–hydrogen exchangers (NHE) transport Na+ into cells in exchange for H+. While there are nine isoforms of NHE in humans, this review focuses on the NHE3 isoform, which is abundantly expressed in the gastrointestinal tract, where it plays a key role in acid–base balance and water homeostasis. NHE3 inhibition in the small intestine results in luminal sodium and water retention, leading to a general decrease in paracellular water flux and diffusional driving force, reduced intestinal sodium absorption, and increased stool sodium excretion. The resulting softer and more frequent stools are the rationale for the development of tenapanor as a novel, first-in-class NHE3 inhibitor to treat irritable bowel syndrome with constipation. NHE3 also has additional therapeutic implications in nephrology. Inhibition of intestinal NHE3 also lowers blood pressure by reducing intestinal sodium absorption. Perhaps, the most novel effect is its ability to decrease intestinal phosphate absorption by inhibiting the paracellular phosphate absorption pathway. Therefore, selective pharmacological inhibition of NHE3 could be a potential therapeutic strategy to treat not only heart failure and hypertension but also hyperphosphatemia. This review presents an overview of the molecular and physiological functions of NHE3 and discusses how these functions translate to potential clinical applications in nephrology.
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Affiliation(s)
- Csaba P Kovesdy
- Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Adebowale Adebiyi
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
| | | | | | - L Darryl Quarles
- Division of Nephrology, University of Tennessee Health Science Center, Memphis, TN, USA
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19
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Yee J, Rosenbaum D, Jacobs JW, Sprague SM. Small Intestinal Phosphate Absorption: Novel Therapeutic Implications. Am J Nephrol 2021; 52:522-530. [PMID: 34515051 DOI: 10.1159/000518110] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 06/24/2021] [Indexed: 01/19/2023]
Abstract
BACKGROUND Chronic kidney disease (CKD) affects approximately 15% of adults in the USA. As CKD progresses, urinary phosphate excretion decreases and results in phosphate retention and, eventually, hyperphosphatemia. As hyperphosphatemia is associated with numerous adverse outcomes, including increased cardiovascular mortality, reduction in phosphorus concentrations is a guideline-recommended, established clinical practice. Dietary phosphate restriction, dialysis, and phosphate binders are currently the only options for phosphate management. However, many patients with hyperphosphatemia have phosphorus concentrations >5.5 mg/dL, despite treatment. SUMMARY This review pre-sents recent advances in the understanding of intestinal phosphate absorption and therapeutic implications. Dietary phosphate is absorbed in the intestine through two distinct pathways, paracellular absorption and transcellular transport. Recent evidence indicates that the paracellular route accounts for 65-80% of total phosphate absorbed. Thus, the paracellular pathway is the dominant mechanism of phosphate absorption. Tenapanor is a first-in-class, non-phosphate binder that inhibits the sodium-hydrogen exchanger 3 or solute carrier family 9 member 3 (SLC9A3) encoded by the SLC9A3 gene, and blocks paracellular phosphate absorption. Key Messages: Targeted inhibition of sodium-hydrogen exchanger 3 effectively reduces paracellular permeability of phosphate. Novel therapies that target the paracellular pathway may improve phosphate control in chronic kidney disease.
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Affiliation(s)
- Jerry Yee
- Nephrology and Hypertension, Henry Ford Hospital, Detroit, Michigan, USA
| | | | | | - Stuart M Sprague
- Division of Nephrology and Hypertension, NorthShore University Health System, Evanston, Illinois, USA
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20
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Lanzer P, Hannan FM, Lanzer JD, Janzen J, Raggi P, Furniss D, Schuchardt M, Thakker R, Fok PW, Saez-Rodriguez J, Millan A, Sato Y, Ferraresi R, Virmani R, St Hilaire C. Medial Arterial Calcification: JACC State-of-the-Art Review. J Am Coll Cardiol 2021; 78:1145-1165. [PMID: 34503684 PMCID: PMC8439554 DOI: 10.1016/j.jacc.2021.06.049] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 01/07/2023]
Abstract
Medial arterial calcification (MAC) is a chronic systemic vascular disorder distinct from atherosclerosis that is frequently but not always associated with diabetes mellitus, chronic kidney disease, and aging. MAC is also a part of more complex phenotypes in numerous less common diseases. The hallmarks of MAC include disseminated and progressive precipitation of calcium phosphate within the medial layer, a prolonged and clinically silent course, and compromise of hemodynamics associated with chronic limb-threatening ischemia. MAC increases the risk of complications during vascular interventions and mitigates their outcomes. With the exception of rare monogenetic defects affecting adenosine triphosphate metabolism, MAC pathogenesis remains unknown, and causal therapy is not available. Implementation of genetics and omics-based approaches in research recognizing the critical importance of calcium phosphate thermodynamics holds promise to unravel MAC molecular pathogenesis and to provide guidance for therapy. The current state of knowledge concerning MAC is reviewed, and future perspectives are outlined.
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Affiliation(s)
- Peter Lanzer
- Middle German Heart Center-Bitterfeld, Bitterfeld-Wolfen Health Care Center, Bitterfeld, Germany.
| | - Fadil M Hannan
- Nuffield Department of Women's & Reproductive Health, University of Oxford, Oxford, United Kingdom
| | - Jan D Lanzer
- Institute for Computational Biomedicine, Bioquant, Faculty of Medicine, Heidelberg University, Heidelberg, Germany; Department of Internal Medicine II, Heidelberg University Hospital, Heidelberg, Germany; Faculty of Biosciences, Heidelberg University, Heidelberg, Heidelberg, Germany
| | | | - Paolo Raggi
- Division of Cardiology, Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Dominic Furniss
- Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
| | - Mirjam Schuchardt
- Department of Nephrology and Medical Intensive Care, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität and Humboldt Universität Berlin, Campus Benjamin Franklin, Berlin, Germany
| | - Rajesh Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Pak-Wing Fok
- Department of Mathematical Sciences, University of Delaware, Newark, Delaware, USA
| | - Julio Saez-Rodriguez
- Institute for Computational Biomedicine, Bioquant, Faculty of Medicine, Heidelberg University, Heidelberg, Germany
| | - Angel Millan
- Institute of Materials Science, University of Zaragoza, Zaragoza, Spain
| | - Yu Sato
- CVPath Institute, Gaithersburg, Maryland, USA
| | | | | | - Cynthia St Hilaire
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Pittsburgh Heart, Lung, and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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21
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Vallée M, Weinstein J, Battistella M, Papineau R, Moseley D, Wong G. Multidisciplinary Perspectives of Current Approaches and Clinical Gaps in the Management of Hyperphosphatemia. Int J Nephrol Renovasc Dis 2021; 14:301-311. [PMID: 34393498 PMCID: PMC8354740 DOI: 10.2147/ijnrd.s318593] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/20/2021] [Indexed: 11/23/2022] Open
Abstract
Population-based studies have shown that most patients with advanced chronic kidney disease (CKD) do not have optimal phosphate levels. Meta-analyses suggest that there is a morbidity and mortality benefit associated with the lowering of serum phosphate levels. However, to date there is no conclusive evidence from randomized controlled trials (RCTs) that lowering serum phosphate levels reduces the risk of morbidity and mortality. However, hyperphosphatemia may pose a risk to patients and treatment should be considered. We therefore sought to conduct a multidisciplinary review to help guide clinical decision-making pending results of ongoing RCTs. Restricting dietary phosphate intake is frequently the first step in the management of hyperphosphatemia. Important considerations when proposing dietary restriction include the patient's socioeconomic status, lifestyle, dietary preferences, comorbidities, and nutritional status. While dietary phosphate restriction may be a valid strategy in certain patients, serum phosphate reductions achieved solely by limiting dietary intake are modest and should be considered in conjunction with other interventions. Conventional dialysis is also typically insufficient; however phosphate removal may be augmented by increased frequency or duration of dialysis, or through enhanced methods such as hemodiafiltration. Phosphate binders have been shown to reduce absorption of dietary phosphate and lower serum phosphate levels. There are several phosphate binders available, and while they all lower phosphate levels to variable degrees, they differ with respect to their pill burden, potential to induce or exacerbate vascular calcification or ectopic calcification, tissue accumulation, safety, and tolerability. The widespread treatment of hyperphosphatemia requires convincing data from RCTs to ascertain whether lowering serum phosphate levels improves patient-important outcomes, as well as the optimal method and degree of phosphate control. In the interim, the decision and approach used to treat hyperphosphatemia should be based on the best available data, as well as patient needs and clinical judgment.
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Affiliation(s)
- Michel Vallée
- Université de Montréal - Hôpital Maisonneuve-Rosemont, Montréal, Québec, Canada
| | - Jordan Weinstein
- Division of Nephrology, St Michael’s Hospital, University of Toronto, Toronto, Ontario, Canada
| | - Marisa Battistella
- University Health Network- Toronto General Hospital, Toronto, Ontario, Canada
| | - Roxanne Papineau
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Québec City, Québec, Canada
| | | | - Gordon Wong
- Trillium Health Partners, Credit Valley Nephrology, Mississauga, Ontario, Canada
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22
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Zhang JY, You HZ, Wang MJ, Zhang Q, Dong XY, Liu JF, Chen J. High-phosphorus diet controlled for sodium elevates blood pressure in healthy adults via volume expansion. J Clin Hypertens (Greenwich) 2021; 23:849-859. [PMID: 33486869 PMCID: PMC8678725 DOI: 10.1111/jch.14182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/23/2020] [Accepted: 01/03/2021] [Indexed: 01/26/2023]
Abstract
Whether increasing exposure to dietary phosphorus can lead to adverse clinical outcomes in healthy people is not clear. In this open‐label prospective cross‐over study, we are to explore the impact of various dietary phosphorus intake on mineral, sodium metabolisms and blood pressure in young healthy adults. There were 3 separate study periods of 5 days, each with a 5 days washout period between different diets interventions. Six young healthy male volunteers with normal nutrition status were recruited in Phase I Clinical Research Center and sequentially exposed to the following diets: (a) normal‐phosphorus diet (NPD): 1500 mg/d, (b) low‐phosphorus diet (LPD): 500 mg/d, (c) high‐phosphorus diet (HPD): 2300 mg/d. HPD induced a significant rise in daily average serum phosphate (1.47 ± 0.02 mmol/L [4.56 ± 0.06 mg/dl]) compared to NPD (1.34 ± 0.02 mmol/L [4.15 ± 0.06 mg/dL]) and LPD (1.17 ± 0.02 mmol/L [3.63 ± 0.06 mg/dL]) (p < .05). Daily average levels of serum parathyroid hormone and fibroblast growth factor 23 in HPD were significantly higher, and serum 1,25(OH)2D3 was remarkably lower than those in LPD. HPD induced a significant decrease in daily average serum aldosterone and an increase in daily average atrial natriuretic peptide level compared to LPD. The 24‐hour urine volume in HPD subjects was less than that in LPD subjects. HPD significantly increased daily average systolic blood pressure by 6.02 ± 1.24 mm Hg compared to NPD and by 8.58 ± 1.24mm Hg compared to LPD (p < .05). Our study provides the first evidence that 5‐day high‐phosphorus diet can induce elevation in SBP in young healthy adults, which may due to volume expansion.
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Affiliation(s)
- Jia-Ying Zhang
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China.,Division of Nutrition, Huashan Hospital, Fudan University, Shanghai, China.,National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Huai-Zhou You
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China.,National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Meng-Jing Wang
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China.,National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Qian Zhang
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China.,National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Xin-Yu Dong
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China
| | - Jing-Fang Liu
- Division of Nutrition, Huashan Hospital, Fudan University, Shanghai, China.,National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Jing Chen
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China.,National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
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23
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King AJ, Kohler J, Fung C, Jiang Z, Quach A, Kumaraswamy P, Chertow GM, Rosenbaum DP. Combination treatment with tenapanor and sevelamer synergistically reduces urinary phosphorus excretion in rats. Am J Physiol Renal Physiol 2021; 320:F133-F144. [PMID: 33283643 DOI: 10.1152/ajprenal.00137.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 11/06/2020] [Accepted: 11/16/2020] [Indexed: 12/22/2022] Open
Abstract
The majority of patients with chronic kidney disease (CKD) receiving dialysis do not achieve target serum phosphorus concentrations, despite treatment with phosphate binders. Tenapanor is a nonbinder, sodium/hydrogen exchanger isoform 3 (NHE3) inhibitor that reduces paracellular intestinal phosphate absorption. This preclinical study evaluated the effect of tenapanor and varying doses of sevelamer carbonate on urinary phosphorus excretion, a direct reflection of intestinal phosphate absorption. We measured 24-h urinary phosphorus excretion in male rats assigned to groups dosed orally with vehicle or tenapanor (0.3 mg/kg/day) and provided a diet containing varying amounts of sevelamer [0-3% (wt/wt)]. We also evaluated the effect of the addition of tenapanor or vehicle on 24-h urinary phosphorus excretion to rats on a stable dose of sevelamer [1.5% (wt/wt)]. When administered together, tenapanor and sevelamer decreased urinary phosphorus excretion significantly more than either tenapanor or sevelamer alone across all sevelamer dose levels. The Bliss statistical model of independence indicated that the combination was synergistic. A stable sevelamer dose [1.5% (wt/wt)] reduced mean ± SE urinary phosphorus excretion by 42 ± 3% compared with vehicle; together, tenapanor and sevelamer reduced residual urinary phosphorus excretion by an additional 37 ± 6% (P < 0.05). Although both tenapanor and sevelamer reduce intestinal phosphate absorption individually, administration of tenapanor and sevelamer together results in more pronounced reductions in intestinal phosphate absorption than if either agent is administered alone. Further evaluation of combination tenapanor plus phosphate binder treatment in patients receiving dialysis with hyperphosphatemia is warranted.
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Affiliation(s)
| | | | - Cyra Fung
- Ardelyx, Incorporated, Fremont, California
| | | | | | | | - Glenn M Chertow
- Division of Nephrology, Stanford University School of Medicine, Stanford, California
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24
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Abstract
Phosphorus, a 5A element with atomic weight of 31, comprises just over 0.6% of the composition by weight of plants and animals. Three isotopes are available for studying phosphorus metabolism and kinetics. 31P is stable, whereas the radioactive isotope 33P has a half-life of 25 days and 32P has a half-life of 14 days. Phosphate ester and phosphoanhydride are common chemical linkages and phosphorus is a key element in organic molecules involved in a wide variety of essential cellular functions. These include biochemical energy transfer via adenosine triphosphate (ATP), maintenance of genetic information with nucleotides DNA and RNA, intracellular signaling via cyclic adenosine monophosphate (cAMP), and membrane structural integrity via glycerophospholipids. However, this review focuses on the metabolism of inorganic phosphorus (Pi) acting as a weak acid. Phosphoric acid has all three hydrogens attached to oxygen and is a weak diprotic acid. It has 3 pKa values: pH 2.2, pH 7.2, and pH 12.7. At physiological pH of 7.4, Pi exists as both H2PO4(-) and HPO4(2-) and acts as an extracellular fluid (ECF) buffer. Pi is the form transported across tissue compartments and cells. Measurement of Pi in biological fluids is based on its reaction with ammonium molybdate which does not measure organic phosphorus. In humans, 80% of the body phosphorus is present in the form of calcium phosphate crystals (apatite) that confer hardness to bone and teeth, and function as the major phosphorus reservoir (Fig. 1). The remainder is present in soft tissues and ECF. Dietary phosphorus, comprising both inorganic and organic forms, is digested in the upper gastrointestinal tract. Absorbed Pi is transported to and from bone, skeletal muscle and soft tissues, and kidney at rates determined by ECF Pi concentration, rate of blood flow, and activity of cell Pi transporters (Fig. 2). During growth, there is net accretion of phosphorus, and with aging, net loss of phosphorus occurs. The bone phosphorus reservoir is depleted and repleted by overall phosphorus requirement. Skeletal muscle is rich in phosphorus used in essential biochemical energy transfer. Kidney is the main regulator of ECF Pi concentration by virtue of having a tubular maximum reabsorptive capacity for Pi (TmPi) that is under close endocrine control. It is also the main excretory pathway for Pi surplus which is passed in urine. Transcellular and paracellular Pi transports are performed by a number of transport mechanisms widely distributed in tissues, and particularly important in gut, bone, and kidney. Pi transporters are regulated by a hormonal axis comprising fibroblast growth factor 23 (FGF23), parathyroid hormone (PTH), and 1,25 dihydroxy vitamin D (1,25D). Pi and calcium (Ca) metabolism are intimately interrelated, and clinically neither can be considered in isolation. Diseases of Pi metabolism affect bone as osteomalacia/rickets, soft tissues as ectopic mineralization, skeletal muscle as myopathy, and kidney as nephrocalcinosis and urinary stone formation. Fig. 1 Content of phosphorus in human adult: skeleton, soft tissue, and extracellular fluid (grams, log scale). Corresponding data for calcium are shown for comparison Fig. 2 Phosphate (Pi) transport to and from tissue compartments in mg/24 h. At a dietary phosphorus of 1400 mg, 1120 mg is absorbed in upper intestine to the ECF, 210 mg returned to intestine by endogenous secretion, resulting in 910 mg net Pi absorption and 490 mg fecal excretion. At bone, 180 mg is deposited by bone formation and 180 mg return to the ECF by bone resorption. At kidney, 5040 mg is filtered at the glomerulus and 4130 mg return to the ECF by tubular reabsorption with 910 mg excreted in the urine. In soft tissue, Pi is exchanged between ECF and cells.
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Affiliation(s)
- Munro Peacock
- Division of Endocrinology, Department of Medicine, Indiana University School of Medicine, 1120 W Michigan Street, CL365, Indianapolis, IN, 46202, USA.
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New drug targets for hypertension: A literature review. Biochim Biophys Acta Mol Basis Dis 2020; 1867:166037. [PMID: 33309796 DOI: 10.1016/j.bbadis.2020.166037] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 11/18/2020] [Accepted: 11/20/2020] [Indexed: 02/06/2023]
Abstract
Hypertension is one of the most prevalent cardiovascular diseases worldwide. However, in the population of resistant hypertension, blood pressure is difficult to control effectively. Moreover, antihypertensive drugs may have adverse effect currently. Hence, new therapeutic targets and treatments are needed to uncovered and exploited to control hypertension and its comorbidities. In the past, classical drug targets, such as the aldosterone receptor, aldosterone synthase, and ACE2/angiotensin 1-7/Mas receptor axis, have been investigated. Recently, vaccines and drugs targeting the gastrointestinal microbiome, which represent drug classes, have also been investigated for the management of blood pressure. In this review, we summarized current knowledge on classical and new drug targets and discussed the potential utility of new drugs in the treatment of hypertension.
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Ikee R, Sasaki N, Yasuda T, Fukazawa S. Chronic Kidney Disease, Gut Dysbiosis, and Constipation: A Burdensome Triplet. Microorganisms 2020; 8:microorganisms8121862. [PMID: 33255763 PMCID: PMC7760012 DOI: 10.3390/microorganisms8121862] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 12/12/2022] Open
Abstract
Gut dysbiosis has been implicated in the progression of chronic kidney disease (CKD). Alterations in the gut environment induced by uremic toxins, the dietary restriction of fiber-rich foods, and multiple drugs may be involved in CKD-related gut dysbiosis. CKD-related gut dysbiosis is considered to be characterized by the expansion of bacterial species producing precursors of harmful uremic toxins, such as indoxyl sulfate and p-cresyl sulfate, and the contraction of species generating beneficial short-chain fatty acids, such as butyrate. Gut-derived uremic toxins cause oxidative stress and pro-inflammatory responses, whereas butyrate exerts anti-inflammatory effects and contributes to gut epithelial integrity. Gut dysbiosis is associated with the disruption of the gut epithelial barrier, which leads to the translocation of endotoxins. Research on CKD-related gut dysbiosis has mainly focused on chronic inflammation and consequent cardiovascular and renal damage. The pathogenic relationship between CKD-related gut dysbiosis and constipation has not yet been investigated in detail. Constipation is highly prevalent in CKD and affects the quality of life of these patients. Under the pathophysiological state of gut dysbiosis, altered bacterial fermentation products may play a prominent role in intestinal dysmotility. In this review, we outline the factors contributing to constipation, such as the gut microbiota and bacterial fermentation; introduce recent findings on the pathogenic link between CKD-related gut dysbiosis and constipation; and discuss potential interventions. This pathogenic link needs to be elucidated in more detail and may contribute to the development of novel treatment options not only for constipation, but also cardiovascular disease in CKD.
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Affiliation(s)
- Ryota Ikee
- Sapporo Nephrology Satellite Clinic, 9-2-15, Hassamu 6-jo, Nishi-ku, Sapporo 063-0826, Japan;
- Correspondence:
| | - Naomi Sasaki
- Sapporo Nephrology Clinic, 20-2-12, Nishimachikita, Nishi-ku, Sapporo 063-0061, Japan; (N.S.); (S.F.)
| | - Takuji Yasuda
- Sapporo Nephrology Satellite Clinic, 9-2-15, Hassamu 6-jo, Nishi-ku, Sapporo 063-0826, Japan;
| | - Sawako Fukazawa
- Sapporo Nephrology Clinic, 20-2-12, Nishimachikita, Nishi-ku, Sapporo 063-0061, Japan; (N.S.); (S.F.)
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Linz B, Saljic A, Hohl M, Gawałko M, Jespersen T, Sanders P, Böhm M, Linz D. Inhibition of sodium-proton-exchanger subtype 3-mediated sodium absorption in the gut: A new antihypertensive concept. IJC HEART & VASCULATURE 2020; 29:100591. [PMID: 32760780 PMCID: PMC7390783 DOI: 10.1016/j.ijcha.2020.100591] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/24/2020] [Accepted: 07/07/2020] [Indexed: 12/22/2022]
Abstract
Arterial hypertension is one of the main contributors to cardiovascular diseases, including stroke, heart failure, and coronary heart disease. Salt plays a major role in the regulation of blood pressure and is one of the most critical factors for hypertension and stroke. At the individual level, effective salt reduction is difficult to achieve and available methods for managing sodium balance are lacking for many patients. As part of the ingested food, salt is absorbed in the gastrointestinal tract by the sodium proton exchanger subtype 3 (NHE3 also known as Slc9a3), influencing extracellular fluid volume and blood pressure. In this review, we discuss the beneficial effects of pharmacological inhibition of NHE3-mediated sodium absorption in the gut and focus on the effect on blood pressure and end-organ damage.
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Affiliation(s)
- Benedikt Linz
- Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Arnela Saljic
- Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mathias Hohl
- Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes
| | - Monika Gawałko
- 1st Department of Cardiology, Medical University of Warsaw, Warsaw, Poland
- Department of Cardiology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Thomas Jespersen
- Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
| | - Michael Böhm
- Kardiologie, Angiologie und Internistische Intensivmedizin, Universitätsklinikum des Saarlandes
| | - Dominik Linz
- Department of Cardiology, Maastricht University Medical Centre, Maastricht, the Netherlands
- Centre for Heart Rhythm Disorders, Royal Adelaide Hospital, University of Adelaide, Adelaide, Australia
- University Maastricht, Cardiovascular Research Institute Maastricht (CARIM), the Netherlands
- Corresponding author at: Maastricht UMC+, Maastricht Heart+Vascular Center, 6202 AZ Maastricht, the Netherlands.
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Abstract
Phosphate is an essential nutrient for life and is a critical component of bone formation, a major signaling molecule, and structural component of cell walls. Phosphate is also a component of high-energy compounds (i.e., AMP, ADP, and ATP) and essential for nucleic acid helical structure (i.e., RNA and DNA). Phosphate plays a central role in the process of mineralization, normal serum levels being associated with appropriate bone mineralization, while high and low serum levels are associated with soft tissue calcification. The serum concentration of phosphate and the total body content of phosphate are highly regulated, a process that is accomplished by the coordinated effort of two families of sodium-dependent transporter proteins. The three isoforms of the SLC34 family (SLC34A1-A3) show very restricted tissue expression and regulate intestinal absorption and renal excretion of phosphate. SLC34A2 also regulates the phosphate concentration in multiple lumen fluids including milk, saliva, pancreatic fluid, and surfactant. Both isoforms of the SLC20 family exhibit ubiquitous expression (with some variation as to which one or both are expressed), are regulated by ambient phosphate, and likely serve the phosphate needs of the individual cell. These proteins exhibit similarities to phosphate transporters in nonmammalian organisms. The proteins are nonredundant as mutations in each yield unique clinical presentations. Further research is essential to understand the function, regulation, and coordination of the various phosphate transporters, both the ones described in this review and the phosphate transporters involved in intracellular transport.
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Affiliation(s)
- Nati Hernando
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Kenneth Gagnon
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Eleanor Lederer
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
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29
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Law JP, Price AM, Pickup L, Radhakrishnan A, Weston C, Jones AM, McGettrick HM, Chua W, Steeds RP, Fabritz L, Kirchhof P, Pavlovic D, Townend JN, Ferro CJ. Clinical Potential of Targeting Fibroblast Growth Factor-23 and αKlotho in the Treatment of Uremic Cardiomyopathy. J Am Heart Assoc 2020; 9:e016041. [PMID: 32212912 PMCID: PMC7428638 DOI: 10.1161/jaha.120.016041] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Chronic kidney disease is highly prevalent, affecting 10% to 15% of the adult population worldwide and is associated with increased cardiovascular morbidity and mortality. As chronic kidney disease worsens, a unique cardiovascular phenotype develops characterized by heart muscle disease, increased arterial stiffness, atherosclerosis, and hypertension. Cardiovascular risk is multifaceted, but most cardiovascular deaths in patients with advanced chronic kidney disease are caused by heart failure and sudden cardiac death. While the exact drivers of these deaths are unknown, they are believed to be caused by uremic cardiomyopathy: a specific pattern of myocardial hypertrophy, fibrosis, with both diastolic and systolic dysfunction. Although the pathogenesis of uremic cardiomyopathy is likely to be multifactorial, accumulating evidence suggests increased production of fibroblast growth factor-23 and αKlotho deficiency as potential major drivers of cardiac remodeling in patients with uremic cardiomyopathy. In this article we review the increasing understanding of the physiology and clinical aspects of uremic cardiomyopathy and the rapidly increasing knowledge of the biology of both fibroblast growth factor-23 and αKlotho. Finally, we discuss how dissection of these pathological processes is aiding the development of therapeutic options, including small molecules and antibodies, directly aimed at improving the cardiovascular outcomes of patients with chronic kidney disease and end-stage renal disease.
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Affiliation(s)
- Jonathan P. Law
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of NephrologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Anna M. Price
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of NephrologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Luke Pickup
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
| | - Ashwin Radhakrishnan
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
| | - Chris Weston
- Institute of Immunology and ImmunotherapyUniversity of BirminghamUnited Kingdom
- NIHR Birmingham Biomedical Research CentreUniversity Hospitals Birmingham NHS Foundation Trust and University of BirminghamUnited Kingdom
| | - Alan M. Jones
- School of PharmacyUniversity of BirminghamUnited Kingdom
| | | | - Winnie Chua
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
| | - Richard P. Steeds
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of CardiologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Larissa Fabritz
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of CardiologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Paulus Kirchhof
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
| | - Davor Pavlovic
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
| | - Jonathan N. Townend
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of CardiologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
| | - Charles J. Ferro
- Birmingham Cardio‐Renal GroupUniversity Hospitals BirminghamUniversity of BirminghamUnited Kingdom
- Institute of Cardiovascular SciencesUniversity of BirminghamUnited Kingdom
- Department of NephrologyUniversity Hospitals Birmingham NHS Foundation TrustBirminghamUnited Kingdom
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30
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Cozzolino M, Ketteler M, Wagner CA. An expert update on novel therapeutic targets for hyperphosphatemia in chronic kidney disease: preclinical and clinical innovations. Expert Opin Ther Targets 2020; 24:477-488. [PMID: 32191548 DOI: 10.1080/14728222.2020.1743680] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Introduction: The management of hyperphosphatemia in patients with chronic kidney disease (CKD) is complicated, requiring a multidisciplinary approach that includes dietary phosphate restriction, dialysis, and phosphate binders.Areas covered: We describe key players involved in regulating inorganic phosphate homeostasis and their differential role in healthy people and different stages of CKD. The contribution of paracellular and transcellular intestinal absorptive mechanisms are also examined. Finally, we illuminate recent therapeutic approaches for hyperphosphatemia in CKD. We searched PubMed/Medline (up to November 2019) using the following terms: chronic kidney disease, dialysis, diet, hyperphosphatemia, NaPi2b, nicotinamide, phosphate binder, secondary hyperparathyroidism, tenapanor and vascular calcification.Expert opinion: The precise mechanisms regulating intestinal phosphate absorption in humans is not completely understood. However, it is now established that this process involves two independent pathways: a) active transport (i.e. transcellular route, via specific ion transporters) and inactive transport (i.e. paracellular route across tight junctions). Dietary phosphate restriction and phosphate-binder use can lead to an undesirable maladaptive increase in phosphate uptake and promote active phosphate transport by increased expression of the gastrointestinal sodium-dependent phosphate transporter, NaPi2b. Nicotinamide may overcome these limitations through the inhibition of NaPi2b, by improved efficacy and reduced phosphate binder use and better compliance.
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Affiliation(s)
- Mario Cozzolino
- Renal Division, ASST Santi Paolo E Carlo, Department of Health Sciences, University of Milan, Milan, Italy
| | - Markus Ketteler
- Department of General Internal Medicine and Nephrology, Robert-Bosch-Krankenhaus, Stuttgart, Germany
| | - Carsten Alexander Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.,National Center of Competence in Research, NCCR Kidney. CH, Zurich, Switzerland
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31
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Block GA, Rosenbaum DP, Yan A, Greasley PJ, Chertow GM, Wolf M. The effects of tenapanor on serum fibroblast growth factor 23 in patients receiving hemodialysis with hyperphosphatemia. Nephrol Dial Transplant 2020; 34:339-346. [PMID: 29617976 PMCID: PMC6365767 DOI: 10.1093/ndt/gfy061] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 02/20/2018] [Indexed: 01/12/2023] Open
Abstract
Background Elevated serum fibroblast growth factor 23 (FGF23) is strongly associated with cardiovascular risk and mortality. Tenapanor, an inhibitor of gastrointestinal sodium/hydrogen exchanger isoform 3, decreased serum phosphate in a randomized, double-blind, placebo-controlled Phase 2 trial (ClinicalTrials.gov identifier NCT02081534) of patients receiving hemodialysis with hyperphosphatemia. Here, we report a secondary analysis of effects on serum FGF23 during that study. Methods After 1–3 weeks of washout of phosphate binders, 162 patients were randomized to receive 4 weeks of treatment with placebo or one of six tenapanor regimens (3 or 30 mg once daily, or 1, 3, 10 or 30 mg twice daily). Intact FGF23 concentrations were determined from serum samples collected at screening, post-washout and end of treatment, assayed in duplicate in a single batch at the end of the study. Results After phosphate-binder washout, serum FGF23 concentrations increased in all groups [range of geometric means: 1430–2605 pg/mL before, to 2601–6294 pg/mL after washout (P < 0.001 for all patients analyzed as a single group)]. Serum FGF23 concentrations subsequently decreased in tenapanor-treated patients (2030–3563 pg/mL), whereas they increased further in placebo-treated patients (6930 pg/mL). In an analysis of covariance, FGF23 decreased by 9.1–27.9% in tenapanor-treated patients and increased by 21.9% in placebo-treated patients (P ≤ 0.001–0.04). Conclusions Following a marked increase in serum FGF23 in response to withdrawal of phosphate binders, tenapanor significantly decreased serum FGF23 in patients receiving hemodialysis with hyperphosphatemia. Further studies are required to explore the long-term effects of controlling FGF23 with tenapanor.
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Affiliation(s)
| | | | | | | | | | - Myles Wolf
- Duke University School of Medicine and Duke Clinical Research Institute, Durham, NC, USA
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32
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Abstract
Over the past 25 years, successive cloning of SLC34A1, SLC34A2 and SLC34A3, which encode the sodium-dependent inorganic phosphate (Pi) cotransport proteins 2a-2c, has facilitated the identification of molecular mechanisms that underlie the regulation of renal and intestinal Pi transport. Pi and various hormones, including parathyroid hormone and phosphatonins, such as fibroblast growth factor 23, regulate the activity of these Pi transporters through transcriptional, translational and post-translational mechanisms involving interactions with PDZ domain-containing proteins, lipid microdomains and acute trafficking of the transporters via endocytosis and exocytosis. In humans and rodents, mutations in any of the three transporters lead to dysregulation of epithelial Pi transport with effects on serum Pi levels and can cause cardiovascular and musculoskeletal damage, illustrating the importance of these transporters in the maintenance of local and systemic Pi homeostasis. Functional and structural studies have provided insights into the mechanism by which these proteins transport Pi, whereas in vivo and ex vivo cell culture studies have identified several small molecules that can modify their transport function. These small molecules represent potential new drugs to help maintain Pi homeostasis in patients with chronic kidney disease - a condition that is associated with hyperphosphataemia and severe cardiovascular and skeletal consequences.
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Cao L, Yuan Z, Liu M, Stock C. (Patho-)Physiology of Na +/H + Exchangers (NHEs) in the Digestive System. Front Physiol 2020; 10:1566. [PMID: 32009977 PMCID: PMC6974801 DOI: 10.3389/fphys.2019.01566] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 12/12/2019] [Indexed: 02/06/2023] Open
Abstract
Na+/H+ exchangers (NHEs) are expressed in virtually all human tissues and organs. Two major tasks of those NHE isoforms that are located in plasma membranes are cell volume control by Na+-uptake and cellular pH regulation by H+-extrusion. Several NHEs, particularly NHE 1–4 and 8, are involved in the pathogenesis of diseases of the digestive system such as inflammatory bowel disease (ulcerative colitis, Crohn’s disease) and gastric and colorectal tumorigenesis. In the present review, we describe the physiological purposes, possible malfunctions and pathophysiological effects of the different NHE isoforms along the alimentary canal from esophagus to colon, including pancreas, liver and gallbladder. Particular attention is paid to the functions of NHEs in injury repair and to the role of NHE1 in Barrett’s esophagus. The impact of NHEs on gut microbiota and intestinal mucosal integrity is also dealt with. As the hitherto existing findings are not always consistent, sometimes even controversial, they are compared and critically discussed.
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Affiliation(s)
- Li Cao
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Zhenglin Yuan
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Mei Liu
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Christian Stock
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hanover, Germany
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The relation between serum phosphorus levels and long-term mortality in Chinese patients with ST-segment elevation myocardial infarction. JOURNAL OF GERIATRIC CARDIOLOGY : JGC 2019; 16:775-781. [PMID: 31700517 PMCID: PMC6828604 DOI: 10.11909/j.issn.1671-5411.2019.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Background Elevated serum phosphorus levels may be associated with adverse outcomes in cardiovascular disease. This study aimed to investigate the relation between serum phosphorus levels and risk of all-cause mortality in Chinese patients with ST-segment elevation myocardial infarction (STEMI) who had preserved renal function at baseline. Methods We enrolled patients with STEMI who had preserved renal function at baseline in Xuanwu Hospital from January 2011 to December 2016. Those patients were divided into four groups based on serum phosphorus levels. All-cause mortality rates were compared between groups. Mean duration of follow up was 54.6 months. We used Cox proportional-hazards models to examine the relation between serum phosphorus levels and all-cause mortality after adjustment for potential confounders. Results 1989 patients were involved and 211 patients (10.6%) died during follow-up. Based on serum phosphorus levels, patients were categorized into the following groups: < 2.50 mg/dL (n = 89), 2.51–3.50 mg/dL (n = 1066), 3.51–4.50 mg/dL (n = 672) and > 4.50 mg/dL (n = 162), respectively. The lowest mortality occurred in patients with serum phosphorus levels between 2.51–3.50 mg/dL, with a multivariable-adjusted hazard ratio of 1.19 (95% CI: 0.64–1.54), 1.37 (95% CI: 1.22–1.74), and 1.46 (95% CI: 1.35–1.83) in patients with serum phosphorus levels of < 2.50 mg/dL, 3.51–4.50 mg/dL and > 4.50 mg/dL, respectively. Conclusions Elevated serum phosphorus levels were associated with all-cause mortality in Chinese patients with STEMI who had preserved renal function at baseline.
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35
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King AJ, Siegel M, He Y, Nie B, Wang J, Koo-McCoy S, Minassian NA, Jafri Q, Pan D, Kohler J, Kumaraswamy P, Kozuka K, Lewis JG, Dragoli D, Rosenbaum DP, O'Neill D, Plain A, Greasley PJ, Jönsson-Rylander AC, Karlsson D, Behrendt M, Strömstedt M, Ryden-Bergsten T, Knöpfel T, Pastor Arroyo EM, Hernando N, Marks J, Donowitz M, Wagner CA, Alexander RT, Caldwell JS. Inhibition of sodium/hydrogen exchanger 3 in the gastrointestinal tract by tenapanor reduces paracellular phosphate permeability. Sci Transl Med 2019; 10:10/456/eaam6474. [PMID: 30158152 DOI: 10.1126/scitranslmed.aam6474] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 10/31/2017] [Accepted: 03/06/2018] [Indexed: 12/16/2022]
Abstract
Hyperphosphatemia is common in patients with chronic kidney disease and is increasingly associated with poor clinical outcomes. Current management of hyperphosphatemia with dietary restriction and oral phosphate binders often proves inadequate. Tenapanor, a minimally absorbed, small-molecule inhibitor of the sodium/hydrogen exchanger isoform 3 (NHE3), acts locally in the gastrointestinal tract to inhibit sodium absorption. Because tenapanor also reduces intestinal phosphate absorption, it may have potential as a therapy for hyperphosphatemia. We investigated the mechanism by which tenapanor reduces gastrointestinal phosphate uptake, using in vivo studies in rodents and translational experiments on human small intestinal stem cell-derived enteroid monolayers to model ion transport physiology. We found that tenapanor produces its effect by modulating tight junctions, which increases transepithelial electrical resistance (TEER) and reduces permeability to phosphate, reducing paracellular phosphate absorption. NHE3-deficient monolayers mimicked the phosphate phenotype of tenapanor treatment, and tenapanor did not affect TEER or phosphate flux in the absence of NHE3. Tenapanor also prevents active transcellular phosphate absorption compensation by decreasing the expression of NaPi2b, the major active intestinal phosphate transporter. In healthy human volunteers, tenapanor (15 mg, given twice daily for 4 days) increased stool phosphorus and decreased urinary phosphorus excretion. We determined that tenapanor reduces intestinal phosphate absorption predominantly through reduction of passive paracellular phosphate flux, an effect mediated exclusively via on-target NHE3 inhibition.
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Affiliation(s)
| | | | - Ying He
- Ardelyx Inc., Fremont, CA 94555, USA
| | | | - Ji Wang
- Ardelyx Inc., Fremont, CA 94555, USA
| | | | | | | | - Deng Pan
- Ardelyx Inc., Fremont, CA 94555, USA
| | | | | | | | | | | | | | - Debbie O'Neill
- University of Alberta, Edmonton, Alberta T6G 1C9, Canada
| | - Allein Plain
- University of Alberta, Edmonton, Alberta T6G 1C9, Canada
| | - Peter J Greasley
- Cardiovascular and Metabolic Disease (CVMD) Translational Medicine Unit, Early Clinical Development, Innovative Medicines and Early Development (IMED) Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | | | - Daniel Karlsson
- Bioscience, CVMD, IMED Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | - Margareta Behrendt
- Bioscience, CVMD, IMED Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | - Maria Strömstedt
- Bioscience, CVMD, IMED Biotech Unit, AstraZeneca Gothenburg, 431 50 Mölndal, Sweden
| | | | - Thomas Knöpfel
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
| | - Eva M Pastor Arroyo
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
| | - Nati Hernando
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
| | - Joanne Marks
- Department of Neuroscience, Physiology and Pharmacology, University College London, Royal Free Campus, London NW3 2PF, UK
| | - Mark Donowitz
- Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich and National Center of Competence in Research Kidney Control of Homeostasis, CH-8057 Zurich, Switzerland
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Thomas L, Xue J, Murali SK, Fenton RA, Dominguez Rieg JA, Rieg T. Pharmacological Npt2a Inhibition Causes Phosphaturia and Reduces Plasma Phosphate in Mice with Normal and Reduced Kidney Function. J Am Soc Nephrol 2019; 30:2128-2139. [PMID: 31409727 DOI: 10.1681/asn.2018121250] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 07/14/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The kidneys play an important role in phosphate homeostasis. Patients with CKD develop hyperphosphatemia in the later stages of the disease. Currently, treatment options are limited to dietary phosphate restriction and oral phosphate binders. The sodium-phosphate cotransporter Npt2a, which mediates a large proportion of phosphate reabsorption in the kidney, might be a good therapeutic target for new medications for hyperphosphatemia. METHODS The authors assessed the effects of the first orally bioavailable Npt2a inhibitor (Npt2a-I) PF-06869206 in normal mice and mice that had undergone subtotal nephrectomy (5/6 Nx), a mouse model of CKD. Dose-response relationships of sodium, chloride, potassium, phosphate, and calcium excretion were assessed in response to the Npt2a inhibitor in both groups of mice. Expression and localization of Npt2a/c and levels of plasma phosphate, calcium, parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF-23) were studied up to 24-hours after Npt2a-I treatment. RESULTS In normal mice, Npt2a inhibition caused a dose-dependent increase in urinary phosphate (ED50 approximately 21 mg/kg), calcium, sodium and chloride excretion. In contrast, urinary potassium excretion, flow rate and urinary pH were not affected dose dependently. Plasma phosphate and PTH significantly decreased after 3 hours, with both returning to near baseline levels after 24 hours. Similar effects were observed in the mouse model of CKD but were reduced in magnitude. CONCLUSIONS Npt2a inhibition causes a dose-dependent increase in phosphate, sodium and chloride excretion associated with reductions in plasma phosphate and PTH levels in normal mice and in a CKD mouse model.
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Affiliation(s)
- Linto Thomas
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida; and
| | - Jianxiang Xue
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida; and
| | | | - Robert A Fenton
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Jessica A Dominguez Rieg
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida; and
| | - Timo Rieg
- Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida; and
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Barreto FC, Barreto DV, Massy ZA, Drüeke TB. Strategies for Phosphate Control in Patients With CKD. Kidney Int Rep 2019; 4:1043-1056. [PMID: 31440695 PMCID: PMC6698320 DOI: 10.1016/j.ekir.2019.06.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/27/2019] [Accepted: 06/03/2019] [Indexed: 02/08/2023] Open
Abstract
Hyperphosphatemia is a common complication in patients with chronic kidney disease (CKD), particularly in those requiring renal replacement therapy. The importance of controlling serum phosphate has long been recognized based on observational epidemiological studies that linked increased phosphate levels to adverse outcomes and higher mortality risk. Experimental data further supported the role of phosphate in the development of bone and cardiovascular diseases. Recent advances in our understanding of the mechanisms involved in phosphate homeostasis have made it clear that the serum phosphate concentration depends on a complex interplay among the kidneys, intestinal tract, and bone, and is tightly regulated by a complex endocrine system. Moreover, the source of dietary phosphate and the use of phosphate-based additives in industrialized foods are additional factors that are of particular importance in CKD. Not surprisingly, the management of hyperphosphatemia is difficult, and, despite a multifaceted approach, it remains unsuccessful in many patients. An additional issue is the fact that the supposedly beneficial effect of phosphate lowering on hard clinical outcomes in interventional trials is a matter of ongoing debate. In this review, we discuss currently available treatment approaches for controlling hyperphosphatemia, including dietary phosphate restriction, reduction of intestinal phosphate absorption, phosphate removal by dialysis, and management of renal osteodystrophy, with particular focus on practical challenges and limitations, and on potential benefits and harms.
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Affiliation(s)
- Fellype Carvalho Barreto
- Service of Nephrology, Department of Internal Medicine, Federal University of Paraná, Curitiba, Paraná, Brazil
| | - Daniela Veit Barreto
- Service of Nephrology, Department of Internal Medicine, Federal University of Paraná, Curitiba, Paraná, Brazil
| | - Ziad A. Massy
- Institut National de la Santé et de la Recherche Médicale U-1018, Team 5, Centre de Recherche en Epidémiologie et Santé des Populations, Versailles Saint-Quentin-en-Yvelines University (Paris-Ile-de-France-Ouest University), Paris-Sud University and Paris Saclay University, Villejuif, France
- Division of Nephrology, Ambroise Paré Hospital, Assistance Publique-Hôpitaux de Paris, Boulogne Billancourt/Paris, France
| | - Tilman B. Drüeke
- Institut National de la Santé et de la Recherche Médicale U-1018, Team 5, Centre de Recherche en Epidémiologie et Santé des Populations, Versailles Saint-Quentin-en-Yvelines University (Paris-Ile-de-France-Ouest University), Paris-Sud University and Paris Saclay University, Villejuif, France
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Saurette M, Alexander RT. Intestinal phosphate absorption: The paracellular pathway predominates? Exp Biol Med (Maywood) 2019; 244:646-654. [PMID: 30764666 DOI: 10.1177/1535370219831220] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
IMPACT STATEMENT This review summarizes the work on transcellular intestinal phosphate absorption, arguing why this pathway is not the predominant pathway in humans consuming a "Western" diet. We then highlight the recent evidence which is strongly consistent with paracellular intestinal phosphate absorption mediating the bulk of intestinal phosphate absorption in humans.
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Affiliation(s)
- Matthew Saurette
- 1 Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2R7, Canada.,2 The Women's & Children's Health Research Institute, Edmonton, Alberta T6G 1C9, Canada
| | - R Todd Alexander
- 1 Department of Physiology, University of Alberta, Edmonton, Alberta T6G 2R7, Canada.,2 The Women's & Children's Health Research Institute, Edmonton, Alberta T6G 1C9, Canada.,3 Department of Pediatrics, University of Alberta, Edmonton, Alberta T6G 2R7, Canada
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Abstract
Calcium kidney stones are common worldwide. Most are idiopathic and composed of calcium oxalate. Calcium phosphate is present in around 80% and may initiate stone formation. Stone production is multifactorial with a polygenic genetic contribution. Phosphaturia is found frequently among stone formers but until recently received scant attention. This review examines possible mechanisms for the phosphaturia and its relevance to stone formation from a wide angle. There is a striking lack of clinical data. Phosphaturia is associated, but not correlated, with hypercalciuria, increased 1,25 dihydroxy-vitamin D [1,25 (OH)2D], and sometimes evidence of disturbances in proximal renal tubular function. Phosphate reabsorption in the proximal renal tubules requires tightly regulated interaction of many proteins. Paracellular flow through intercellular tight junctions is the major route of phosphate absorption from the intestine and can be reduced therapeutically in hyperphosphatemic patients. In monogenic defects stones develop when phosphaturia is associated with hypercalciuria, generally explained by increased 1,25 (OH)2D production in response to hypophosphatemia. Calcification does not occur in disorders with increased FGF23 when phosphaturia occurs in isolation and 1,25 (OH)2D is suppressed. Candidate gene studies have identified mutations in the phosphate transporters, but in few individuals. One genome-wide study identified a polymorphism of the phosphate transporter gene SLC34A4 associated with stones. Others did not find mutations obviously linked to phosphate reabsorption. Future genetic studies should have a wide trawl and should focus initially on groups of patients with clearly defined phenotypes. The global data should be pooled.
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Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom.
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40
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Lederer E, Wagner CA. Clinical aspects of the phosphate transporters NaPi-IIa and NaPi-IIb: mutations and disease associations. Pflugers Arch 2018; 471:137-148. [DOI: 10.1007/s00424-018-2246-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 12/05/2018] [Indexed: 12/12/2022]
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Sorribas V, Guillén N, Sosa C. Substrates and inhibitors of phosphate transporters: from experimental tools to pathophysiological relevance. Pflugers Arch 2018; 471:53-65. [DOI: 10.1007/s00424-018-2241-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Revised: 11/21/2018] [Accepted: 11/25/2018] [Indexed: 12/26/2022]
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McHugh DR, Cotton CU, Moss FJ, Vitko M, Valerio DM, Kelley TJ, Hao S, Jafri A, Drumm ML, Boron WF, Stern RC, McBennett K, Hodges CA. Linaclotide improves gastrointestinal transit in cystic fibrosis mice by inhibiting sodium/hydrogen exchanger 3. Am J Physiol Gastrointest Liver Physiol 2018; 315:G868-G878. [PMID: 30118317 PMCID: PMC9925117 DOI: 10.1152/ajpgi.00261.2017] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Gastrointestinal dysfunction in cystic fibrosis (CF) is a prominent source of pain among patients with CF. Linaclotide, a guanylate cyclase C (GCC) receptor agonist, is a US Food and Drug Administration-approved drug prescribed for chronic constipation but has not been widely used in CF, as the cystic fibrosis transmembrane conductance regulator (CFTR) is the main mechanism of action. However, anecdotal clinical evidence suggests that linaclotide may be effective for treating some gastrointestinal symptoms in CF. The goal of this study was to determine the effectiveness and mechanism of linaclotide in treating CF gastrointestinal disorders using CF mouse models. Intestinal transit, chloride secretion, and intestinal lumen fluidity were assessed in wild-type and CF mouse models in response to linaclotide. CFTR and sodium/hydrogen exchanger 3 (NHE3) response to linaclotide was also evaluated. Linaclotide treatment improved intestinal transit in mice carrying either F508del or null Cftr mutations but did not induce detectable Cl- secretion. Linaclotide increased fluid retention and fluidity of CF intestinal contents, suggesting inhibition of fluid absorption. Targeted inhibition of sodium absorption by the NHE3 inhibitor tenapanor produced improvements in gastrointestinal transit similar to those produced by linaclotide treatment, suggesting that inhibition of fluid absorption by linaclotide contributes to improved gastrointestinal transit in CF. Our results demonstrate that linaclotide improves gastrointestinal transit in CF mouse models by increasing luminal fluidity through inhibiting NHE3-mediated sodium absorption. Further studies are necessary to assess whether linaclotide could improve CF intestinal pathologies in patients. GCC signaling and NHE3 inhibition may be therapeutic targets for CF intestinal manifestations. NEW & NOTEWORTHY Linaclotide's primary mechanism of action in alleviating chronic constipation is through cystic fibrosis transmembrane conductance regulator (CFTR), negating its use in patients with cystic fibrosis (CF). For the first time, our findings suggest that in the absence of CFTR, linaclotide can improve fluidity of the intestinal lumen through the inhibition of sodium/hydrogen exchanger 3. These findings suggest that linaclotide could improve CF intestinal pathologies in patients.
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Affiliation(s)
- Daniel R. McHugh
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Calvin U. Cotton
- 2Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio,3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Fraser J. Moss
- 2Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Megan Vitko
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Dana M. Valerio
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Thomas J. Kelley
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio,4Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Shuyu Hao
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Anjum Jafri
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Mitchell L. Drumm
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio,3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Walter F. Boron
- 2Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio,5Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio,6Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Robert C. Stern
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio,7Rainbow Babies and Children’s Hospital, Cleveland, Ohio
| | - Kimberly McBennett
- 3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio,7Rainbow Babies and Children’s Hospital, Cleveland, Ohio
| | - Craig A. Hodges
- 1Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, Ohio,3Department of Pediatrics, Case Western Reserve University School of Medicine, Cleveland, Ohio
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Marks J. The role of SLC34A2 in intestinal phosphate absorption and phosphate homeostasis. Pflugers Arch 2018; 471:165-173. [PMID: 30343332 PMCID: PMC6325986 DOI: 10.1007/s00424-018-2221-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 10/08/2018] [Accepted: 10/10/2018] [Indexed: 12/13/2022]
Abstract
There has recently been significant interest in the concept of directly targeting intestinal phosphate transport to control hyperphosphatemia in patients with chronic kidney disease. However, we do not have a complete understanding of the cellular mechanisms that govern dietary phosphate absorption. Studies in the 1970s documented both active and passive pathways for intestinal phosphate absorption. However, following the cloning of the intestinal SLC34 cotransporter, NaPi-IIb, much of the research focused on the role of this protein in active transcellular phosphate absorption and the factors involved in its regulation. Generation of a conditional NaPi-IIb knockout mouse has demonstrated that this protein is critical for the maintenance of skeletal integrity during periods of phosphate restriction and that under normal physiological conditions, the passive sodium-independent pathway is likely be the more dominant pathway for intestinal phosphate absorption. The review aims to summarise the most recent developments in our understanding of the role of the intestine in phosphate homeostasis, including the acute and chronic renal adaptations that occur in response to dietary phosphate intake. Evidence regarding the overall contribution of the transcellular and paracellular pathways for phosphate absorption will be discussed, together with the clinical benefit of inhibiting these pathways for the treatment of hyperphosphatemia in chronic kidney disease.
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Affiliation(s)
- Joanne Marks
- Department of Neuroscience, Physiology and Pharmacology, Royal Free Campus, University College London, Rowland Hill Street, London, NW3 2PF, UK.
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44
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Abstract
Purpose of Review The purpose of this review is to summarize the most recent data available on advances in development of novel medical treatments for hypertension and related comorbidities. Recent Findings Approximately half of all hypertensive patients have not achieved goal blood pressure with current available antihypertensive medications. Recent landmark studies and new hypertension guidelines have called for stricter blood pressure control, creating a need for better strategies for lowering blood pressure. This has led to a shift in focus, in recent years, to the development of combination pills as a means of achieving improved blood pressure control by increasing adherence to prescribed medications along with further research and development of promising novel drugs based on discovery of new molecular targets such as the counter-regulatory renin-angiotensin system. Summary Fixed-dose combination pills and novel treatments based on recently discovered pathogenic mechanisms of hypertension that have demonstrated promising results as treatments for hypertension and related comorbidities will be discussed in this review.
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Affiliation(s)
- Jared Davis
- Department of Medicine, University of Alabama at Birmingham, BDB 327, 1720 2nd Ave S, Birmingham, AL, 35294, USA.
| | - Suzanne Oparil
- UAB Vascular Biology and Hypertension Program, Division of Cardiovascular Disease, University of Alabama at Birmingham, ZRB 1034, 703 19th St S, Birmingham, AL, 35233, USA
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45
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Rosenbaum DP, Yan A, Jacobs JW. Pharmacodynamics, Safety, and Tolerability of the NHE3 Inhibitor Tenapanor: Two Trials in Healthy Volunteers. Clin Drug Investig 2018; 38:341-351. [PMID: 29363027 PMCID: PMC5856883 DOI: 10.1007/s40261-017-0614-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Background Tenapanor, a small molecule with minimal systemic availability, is a first-in-class sodium/hydrogen exchanger 3 (NHE3) inhibitor that acts in the gut. Here, we evaluate the pharmacodynamics and safety of tenapanor in healthy adults. Methods Two phase I, single-center, randomized, double-blind, placebo-controlled studies were performed. The first study assessed single-ascending oral tenapanor doses of 10, 50, 150, 450, and 900 mg (n = 8 per group; six tenapanor, two placebo) and multiple ascending doses over 7 days of 3, 10, 30, and 100 mg q.d. (n = 10 per group; eight tenapanor, two placebo). In the second study, different tenapanor regimens were evaluated over 7 days (n = 15 per group; 12 tenapanor, three placebo): 15 mg twice daily (b.i.d.), 30 mg once daily (q.d.), 30 mg b.i.d., 30 mg three times daily (t.i.d.), 60 mg b.i.d., escalating b.i.d. dose (daily total 30–90 mg), 30 mg b.i.d. with psyllium. Results Tenapanor produced generally dose-dependent increases in stool sodium excretion and decreases in urinary sodium excretion versus placebo; in addition, twice-daily dosing appeared to have a greater effect on sodium absorption than once-daily dosing with an equivalent daily dose. Tenapanor softened stool consistency and increased stool frequency and weight from baseline versus placebo. Tenapanor concentrations were below the quantification limit (0.5 ng/ml) in 98.5% of 895 plasma samples. Adverse events were mild or moderate in severity, and were typically gastrointestinal in nature. There were no clinically relevant changes in serum electrolytes. Conclusions Tenapanor was well tolerated and resulted in reduced intestinal sodium absorption and softer stool consistency versus placebo. Systemic exposure to tenapanor was minimal. These results support potential use of tenapanor in patients who could benefit from modification of gastrointestinal sodium balance. ClinicalTrials.gov identifiers NCT02819687, NCT02796131. Electronic supplementary material The online version of this article (10.1007/s40261-017-0614-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- David P Rosenbaum
- Ardelyx Inc., 34175 Ardenwood Blvd, Suite 200, Fremont, CA, 94555, USA.
| | - Andrew Yan
- Ardelyx Inc., 34175 Ardenwood Blvd, Suite 200, Fremont, CA, 94555, USA
| | - Jeffrey W Jacobs
- Ardelyx Inc., 34175 Ardenwood Blvd, Suite 200, Fremont, CA, 94555, USA
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Fouque D, Vervloet M, Ketteler M. Targeting Gastrointestinal Transport Proteins to Control Hyperphosphatemia in Chronic Kidney Disease. Drugs 2018; 78:1171-1186. [PMID: 30022383 PMCID: PMC6132443 DOI: 10.1007/s40265-018-0950-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Management of hyperphosphatemia in patients with dialysis-dependent chronic kidney disease remains a major challenge, requiring a multifaceted approach that includes dietary phosphate restriction, dialysis, and phosphate binders. However, these treatments fail to meet serum phosphate targets in many patients, potentially further exacerbating the significant morbidity and mortality burden associated with the disease. Recent advances in our understanding of the mechanisms underlying phosphate homeostasis have shed new light on the issue and suggest that gastrointestinal transport proteins may be promising targets for new hyperphosphatemia treatments. Drugs that inhibit or downregulate these transport proteins, and thus reduce phosphate uptake from the gut, may overcome some of the limitations of existing phosphate-lowering strategies, such as interdialytic rises in serum phosphate levels, poor adherence to dietary and phosphate-binder regimens, and maladaptive responses that can increase gastrointestinal phosphate absorption. Here, we review the latest preclinical and clinical data for two candidates in this novel drug class: tenapanor, a small-molecule inhibitor of the sodium/hydrogen ion-exchanger isoform 3, and nicotinamide, an inhibitor of sodium-phosphate-2b cotransporters. We also discuss how potential synergies in their mechanisms of action suggest that coadministering phosphate binders with sodium-phosphate-2b cotransporter inhibitors may yield additive benefits over traditional phosphate-binder therapy.
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Affiliation(s)
- Denis Fouque
- Department of Nephrology, Centre Hospitalier Lyon-Sud, Université de Lyon, Carmen, 165 Chemin du Grand Revoyet, 69495, Pierre-Bénite, France
| | - Marc Vervloet
- Department of Nephrology and Amsterdam Cardiovascular Sciences (ACS), VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, Netherlands
| | - Markus Ketteler
- Division of Nephrology, Klinikum Coburg GmbH, Ketschendorfer Str. 33, D-96450, Coburg, Germany.
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47
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Hernando N, Wagner CA. Mechanisms and Regulation of Intestinal Phosphate Absorption. Compr Physiol 2018; 8:1065-1090. [PMID: 29978897 DOI: 10.1002/cphy.c170024] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
States of hypo- and hyperphosphatemia have deleterious consequences including rickets/osteomalacia and renal/cardiovascular disease, respectively. Therefore, the maintenance of appropriate plasma levels of phosphate is an essential requirement for health. This control is executed by the collaborative action of intestine and kidney whose capacities to (re)absorb phosphate are regulated by a number of hormonal and metabolic factors, among them parathyroid hormone, fibroblast growth factor 23, 1,25(OH)2 vitamin D3 , and dietary phosphate. The molecular mechanisms responsible for the transepithelial transport of phosphate across enterocytes are only partially understood. Indeed, whereas renal reabsorption entirely relies on well-characterized active transport mechanisms of phosphate across the renal proximal epithelia, intestinal absorption proceeds via active and passive mechanisms, with the molecular identity of the passive component still unknown. The active absorption of phosphate depends mostly on the activity and expression of the sodium-dependent phosphate cotransporter NaPi-IIb (SLC34A2), which is highly regulated by many of the factors, mentioned earlier. Physiologically, the contribution of NaPi-IIb to the maintenance of phosphate balance appears to be mostly relevant during periods of low phosphate availability. Therefore, its role in individuals living in industrialized societies with high phosphate intake is probably less relevant. Importantly, small increases in plasma phosphate, even within normal range, associate with higher risk of cardiovascular disease. Therefore, therapeutic approaches to treat hyperphosphatemia, including dietary phosphate restriction and phosphate binders, aim at reducing intestinal absorption. Here we review the current state of research in the field. © 2017 American Physiological Society. Compr Physiol 8:1065-1090, 2018.
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Affiliation(s)
- Nati Hernando
- National Center for Competence in Research NCCR Kidney.CH, Institute of Physiology, University Zurich-Irchel, Zurich, Switzerland
| | - Carsten A Wagner
- National Center for Competence in Research NCCR Kidney.CH, Institute of Physiology, University Zurich-Irchel, Zurich, Switzerland
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Carfagna F, Del Vecchio L, Pontoriero G, Locatelli F. Current and potential treatment options for hyperphosphatemia. Expert Opin Drug Saf 2018; 17:597-607. [PMID: 29783873 DOI: 10.1080/14740338.2018.1476487] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Hyperphosphatemia is common in late stages of chronic kidney disease and is often associated with elevated parathormone levels, abnormal bone mineralization, extra-osseous calcification, and increased risk of cardiovascular events and death. Several classes of oral phosphate binders are available to help control plasma phosphorus levels. Although effective at lowering serum phosphorus, they all have safety, tolerability, and compliance issues that need to be considered when selecting which one to use. AREAS COVERED This paper reviews the most established treatment options for hyperphosphatemia, in patients with chronic kidney disease, focusing on the new inhibitors of active phosphate absorption. EXPERT OPINION The prevention and the treatment of hyperphosphatemia is today far to be satisfactory. Nonetheless, an extending range of phosphate binders are now available. Aluminum has potentially serious toxic risks. Calcium-based binders are very effective but can lead to hypercalcemia and/or positive calcium balance and progression of cardiovascular calcification. No long-term data are available for the new calcium acetate/magnesium combination product. Lanthanum is an effective phosphate binder, and long-term effects of tissue deposition seem clinically irrelevant. Sevelamer, appear to have profiles that would lead to pleiotropic effects and reduced progression of vascular calcification, and the main adverse events seen with these agents are gastrointestinal. Iron has a powerful capability of binding phosphate, thus numerous preparations are available, both with and without significant systemic absorption of the iron component. The inhibitors of active intestinal phosphate transport, with their very selective mechanism of action and low pill burden seem the most interesting approach; however, do not seem at present to be effective alone, in reducing serum phosphorus levels.
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Affiliation(s)
- Fabio Carfagna
- a Department of Nephrology and Dialysis , A. Manzoni Hospital ASST Lecco , Lecco , Italy
| | - Lucia Del Vecchio
- a Department of Nephrology and Dialysis , A. Manzoni Hospital ASST Lecco , Lecco , Italy
| | - Giuseppe Pontoriero
- a Department of Nephrology and Dialysis , A. Manzoni Hospital ASST Lecco , Lecco , Italy
| | - Francesco Locatelli
- a Department of Nephrology and Dialysis , A. Manzoni Hospital ASST Lecco , Lecco , Italy
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Lenglet A, Liabeuf S, El Esper N, Brisset S, Mansour J, Lemaire-Hurtel AS, Mary A, Brazier M, Kamel S, Mentaverri R, Choukroun G, Fournier A, Massy ZA. Efficacy and safety of nicotinamide in haemodialysis patients: the NICOREN study. Nephrol Dial Transplant 2018; 32:870-879. [PMID: 27190329 DOI: 10.1093/ndt/gfw042] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 02/09/2016] [Indexed: 12/16/2022] Open
Abstract
Background Nicotinamide (NAM) has been proposed as an alternative treatment to phosphate binders for hyperphosphataemia in chronic kidney disease. Methods The NICOREN multicentre, open-label and randomized study was designed to examine non-inferiority and safety of NAM when compared with sevelamer (SEV) in chronic haemodialysis patients. One hundred patients were randomized to either NAM or SEV treatment for 24 weeks. Serum biochemistry and NAM's main metabolite, N -methyl-2-pyridone-5-carboxamide (2PY), were measured to assess compliance, efficacy and safety. Results After 24 weeks, we observed a comparable decrease in serum phosphorus in the NAM and SEV treatment arms, from 2.1 ± 0.4 to 1.8 ± 0.5 and 2.3 ± 0.5 to 1.7 ± 0.5 mM (P = not significant), respectively. The criterion for non-inferiority was, however, not met due to a more limited number of patients being included than planned. Treatment discontinuation due to adverse events was 1.6 times higher in the NAM than in the SEV group with only 55% of study completers in the NAM arm versus 90% in the SEV arm. Thrombocytopenia was observed in four NAM-treated patients. Serum 2PY levels were comparable at baseline, but increased markedly in the NAM group, but not in the SEV group, at 24 weeks (P < 0.0001). Conclusions Thus, both drugs are equally effective in lowering serum phosphorus, but patients' tolerance of NAM was largely inferior to that of SEV. Extremely high 2PY levels may contribute to NAM's side effects.
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Affiliation(s)
- Aurélie Lenglet
- INSERM U1088, Jules Verne University of Picardie, Amiens, France.,Pharmacy, University Hospital, Amiens, France
| | - Sophie Liabeuf
- INSERM U1088, Jules Verne University of Picardie, Amiens, France.,Clinical Research Centre and Division of Clinical Pharmacology, University Hospital, Amiens, France
| | - Najeh El Esper
- Department of Nephrology Internal Medicine, Dialysis, Transplantation and Intensive Care, University Hospital, Amiens, France
| | - Sandrine Brisset
- Clinical Research Centre and Division of Clinical Pharmacology, University Hospital, Amiens, France
| | - Janette Mansour
- Department of Nephrology, Centre Hospitalier de Soissons, Soissons, France
| | | | - Aurelien Mary
- INSERM U1088, Jules Verne University of Picardie, Amiens, France.,Pharmacy, University Hospital, Amiens, France
| | - Michel Brazier
- INSERM U1088, Jules Verne University of Picardie, Amiens, France.,Laboratory of Endocrine and Bone Biology, University Hospital, Amiens, France
| | - Said Kamel
- INSERM U1088, Jules Verne University of Picardie, Amiens, France.,Laboratory of Endocrine and Bone Biology, University Hospital, Amiens, France
| | - Romuald Mentaverri
- INSERM U1088, Jules Verne University of Picardie, Amiens, France.,Laboratory of Endocrine and Bone Biology, University Hospital, Amiens, France
| | - Gabriel Choukroun
- INSERM U1088, Jules Verne University of Picardie, Amiens, France.,Department of Nephrology Internal Medicine, Dialysis, Transplantation and Intensive Care, University Hospital, Amiens, France
| | - Albert Fournier
- Department of Nephrology Internal Medicine, Dialysis, Transplantation and Intensive Care, University Hospital, Amiens, France
| | - Ziad A Massy
- Division of Nephrology, Ambroise Paré Hospital-APHP and Paris Ile de France Ouest University (UVSQ), Boulogne-Billancourt, France.,Inserm U-1018, Centre de recherche en épidémiologie et santé des populations (CESP), Equipe 5, Villejuif, France.,Paris-Sud University (PSU), Orsay, France.,University of Paris Ouest-Versailles-Saint-Quentin-en-Yvelines (UVSQ), Versailles, France
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Visconti L, Cernaro V, Calimeri S, Lacquaniti A, De Gregorio F, Ricciardi CA, Lacava V, Santoro D, Buemi M. The Myth of Water and Salt: From Aquaretics to Tenapanor. J Ren Nutr 2017; 28:73-82. [PMID: 29146141 DOI: 10.1053/j.jrn.2017.06.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 05/13/2017] [Accepted: 06/09/2017] [Indexed: 12/21/2022] Open
Abstract
The impact of water intake has been studied in several renal diseases. For example, increasing water intake is useful to prevent primary and secondary nephrolithiasis. In autosomal dominant polycystic kidney disease, arginine vasopressin (AVP) is involved in the progression of the disease, and water intake could play a therapeutic role by inhibiting the synthesis of AVP, but its efficacy is still controversial. Conversely, the use of aquaretics, which are antagonists of AVP V2 receptors, results in the reduction of the increase rate of total kidney volume with a slower decline of glomerular filtration rate. In chronic kidney disease, AVP contributes to glomerular hyperfiltration, arterial hypertension, and synthesis of renin, resulting in renal sclerosis. Increased water intake could reduce AVP activation determining a potential protective effect on the kidney, but its efficacy has not yet been clearly demonstrated. On the other side, sodium and potassium play an important role in the control of arterial blood pressure and are involved in the development and progression of chronic kidney disease. Reduction of sodium intake and increase of potassium intake determine a decrease of arterial blood pressure with a beneficial effect on the kidney; however, adherence to sodium restriction is very poor. Regarding this, sodium-hydrogen exchanger isoform 3 inhibitors may reduce sodium absorption in the gut. The most recent sodium-hydrogen exchanger isoform 3 inhibitor, known as tenapanor, reduces extracellular fluid volume, left ventricular hypertrophy, albuminuria, and blood pressure in experimental studies and increases fecal loss of sodium in humans.
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Affiliation(s)
- Luca Visconti
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy.
| | - Valeria Cernaro
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Sebastiano Calimeri
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Antonio Lacquaniti
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Francesca De Gregorio
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | | | - Viviana Lacava
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Domenico Santoro
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
| | - Michele Buemi
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy
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