101
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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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102
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Hureaux M, Molin A, Jay N, Saliou AH, Spaggiari E, Salomon R, Benachi A, Vargas-Poussou R, Heidet L. Prenatal hyperechogenic kidneys in three cases of infantile hypercalcemia associated with SLC34A1 mutations. Pediatr Nephrol 2018; 33:1723-1729. [PMID: 29959532 DOI: 10.1007/s00467-018-3998-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/21/2018] [Accepted: 05/25/2018] [Indexed: 01/13/2023]
Abstract
BACKGROUND Prenatal diagnosis of hyperechogenic kidneys is associated with a wide range of etiologies and prognoses. The recent advances in fetal ultrasound associated with the development of next-generation sequencing for molecular analysis have enlarged the spectrum of etiologies, making antenatal diagnosis a very challenging discipline. Of the various known causes of hyperechogenic fetal kidneys, calcium and phosphate metabolism disorders represent a rare cause. An accurate diagnosis is crucial for providing appropriate genetic counseling and medical follow-up after birth. METHODS We report on three cases of fetal hyperechogenic kidneys corresponding to postnatal diagnosis of nephrocalcinosis. In all cases, antenatal ultrasound showed hyperechogenic kidneys of normal to large size from 22 gestational weeks, with a normal amount of amniotic fluid. Postnatal ultrasound follow-up showed nephrocalcinosis associated with hypercalcemia, hypercalciuria, elevated 1,25(OH)2-vitamin D, and suppressed parathyroid hormone levels. RESULTS Molecular genetic analysis by next-generation sequencing performed after birth in the three newborns revealed biallelic pathogenic variants in the SLC34A1 gene, encoding the sodium/phosphate cotransporter type 2 (Npt2a), confirming the diagnosis of infantile hypercalcemia. CONCLUSIONS Nephrocalcinosis due to infantile hypercalcemia can be a cause of fetal hyperechogenic kidneys, which suggests early antenatal anomaly of calcium and phosphate metabolism. This entity should be considered in differential diagnosis. Postnatal follow-up of infants with hyperechogenic kidneys should include evaluation of calcium and phosphate metabolism.
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Affiliation(s)
- Marguerite Hureaux
- Département de Génétique, Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, 20-40 rue Leblanc, 75015, Paris, France.,Paris Descartes-Sorbonne Paris Cité University, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Filière ORKiD, Paris, France
| | - Arnaud Molin
- Service de Génétique, Centre Hospitalier Universitaire de Caen, Caen, France.,Centre de Référence des Maladies rares du Métabolisme du calcium et du phosphate (filière OSCAR), FilièreOSCAR, Paris, France.,Université Caen Normandie, UFR de médecine (Medical School), EA7450 BioTarGen, Caen, France
| | - Nadine Jay
- Centre Hospitalier Universitaire de Brest, Service de Pédiatrie et Génétique Médicale, Brest, France
| | | | - Emmanuel Spaggiari
- Département de Gynécologie-Obstétrique, Assistance Publique Hôpitaux de Paris, Hôpital Necker - Enfants Malades, Paris, France
| | - Rémi Salomon
- Paris Descartes-Sorbonne Paris Cité University, Paris, France.,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Filière ORKiD, Paris, France.,Département de Néphrologie Pédiatrique, Assistance Publique Hôpitaux de Paris, Hôpital Necker - Enfants Malades, Paris, France
| | - Alexandra Benachi
- Département de Gynécologie-Obstétrique, Assistance Publique Hôpitaux de Paris, Hôpital Antoine-Béclère, Université Paris-Sud, Clamart, France
| | - Rosa Vargas-Poussou
- Département de Génétique, Hôpital Européen Georges Pompidou, Assistance Publique Hôpitaux de Paris, 20-40 rue Leblanc, 75015, Paris, France. .,Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Filière ORKiD, Paris, France.
| | - Laurence Heidet
- Centre de Référence des Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Filière ORKiD, Paris, France.,Département de Néphrologie Pédiatrique, Assistance Publique Hôpitaux de Paris, Hôpital Necker - Enfants Malades, Paris, France
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103
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Michigami T, Kawai M, Yamazaki M, Ozono K. Phosphate as a Signaling Molecule and Its Sensing Mechanism. Physiol Rev 2018; 98:2317-2348. [DOI: 10.1152/physrev.00022.2017] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In mammals, phosphate balance is maintained by influx and efflux via the intestines, kidneys, bone, and soft tissue, which involves multiple sodium/phosphate (Na+/Pi) cotransporters, as well as regulation by several hormones. Alterations in the levels of extracellular phosphate exert effects on both skeletal and extra-skeletal tissues, and accumulating evidence has suggested that phosphate itself evokes signal transduction to regulate gene expression and cell behavior. Several in vitro studies have demonstrated that an elevation in extracellular Piactivates fibroblast growth factor receptor, Raf/MEK (mitogen-activated protein kinase/ERK kinase)/ERK (extracellular signal-regulated kinase) pathway and Akt pathway, which might involve the type III Na+/Picotransporter PiT-1. Excessive phosphate loading can lead to various harmful effects by accelerating ectopic calcification, enhancing oxidative stress, and dysregulating signal transduction. The responsiveness of mammalian cells to altered extracellular phosphate levels suggests that they may sense and adapt to phosphate availability, although the precise mechanism for phosphate sensing in mammals remains unclear. Unicellular organisms, such as bacteria and yeast, use some types of Pitransporters and other molecules, such as kinases, to sense the environmental Piavailability. Multicellular animals may need to integrate signals from various organs to sense the phosphate levels as a whole organism, similarly to higher plants. Clarification of the phosphate-sensing mechanism in humans may lead to the development of new therapeutic strategies to prevent and treat diseases caused by phosphate imbalance.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Masanobu Kawai
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Miwa Yamazaki
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
| | - Keiichi Ozono
- Department of Bone and Mineral Research, Research Institute, Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Izumi, Osaka, Japan; and Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Osaka, Japan
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104
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Stremke ER, Hill Gallant KM. Intestinal Phosphorus Absorption in Chronic Kidney Disease. Nutrients 2018; 10:E1364. [PMID: 30249044 PMCID: PMC6213936 DOI: 10.3390/nu10101364] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 09/17/2018] [Accepted: 09/19/2018] [Indexed: 02/06/2023] Open
Abstract
Chronic kidney disease (CKD) affects approximately 10% of adults worldwide. Dysregulation of phosphorus homeostasis which occurs in CKD leads to development of CKD-Mineral Bone Disorder (CKD-MBD) and contributes to increased morbidity and mortality in these patients. Phosphorus is regulated by multiple hormones (parathyroid hormone (PTH), 1,25-dihyxdroxyvitamin D (1,25D), and fibroblast growth factor 23 (FGF23)) and tissues (kidney, intestine, parathyroid glands, and bone) to maintain homeostasis. In health, the kidneys are the major site of regulation for phosphorus homeostasis. However, as kidney function declines, the ability of the kidneys to adequately excrete phosphorus is reduced. The hormonal changes that occur with CKD would suggest that the intestine should compensate for impaired renal phosphorus excretion by reducing fractional intestinal phosphorus absorption. However, limited studies in CKD animal models and patients with CKD suggest that there may be a break in this homeostatic response where the intestine fails to compensate. As many existing therapies for phosphate management in CKD are aimed at reducing absolute intestinal phosphorus absorption, better understanding of the factors that influence fractional and absolute absorption, the mechanism by which intestinal phosphate absorption occurs, and how CKD modifies these is a much-needed area of study.
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Affiliation(s)
- Elizabeth R Stremke
- Department of Nutrition Science, Purdue University, West Lafayette, IN 47907, USA.
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105
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Tatsumi S, Katai K, Kaneko I, Segawa H, Miyamoto KI. NAD metabolism and the SLC34 family: evidence for a liver-kidney axis regulating inorganic phosphate. Pflugers Arch 2018; 471:109-122. [PMID: 30218374 DOI: 10.1007/s00424-018-2204-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 08/29/2018] [Accepted: 09/06/2018] [Indexed: 12/18/2022]
Abstract
The solute carrier 34 (SLC34) family of membrane transporters is a major contributor to Pi homeostasis. Many factors are involved in regulating the SLC34 family. The roles of the bone mineral metabolism factors parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) in Pi homeostasis are well studied. Intracellular Pi is thought to be involved in energy metabolism, such as ATP production. Under certain conditions of altered energy metabolism, plasma Pi concentrations are affected by the regulation of a Pi shift into cells or release from the tissues. We recently investigated the mechanism of hepatectomy-related hypophosphatemia, which is thought to involve an unknown phosphaturic factor. Hepatectomy-related hypophosphatemia is due to impaired nicotinamide adenine dinucleotide (NAD) metabolism through its effects on the SLC34 family in the liver-kidney axis. The oxidized form of NAD, NAD+, is an essential cofactor in various cellular biochemical reactions. Levels of NAD+ and its reduced form NADH vary with the availability of dietary energy and nutrients. Nicotinamide phosphoribosyltransferase (Nampt) generates a key NAD+ intermediate, nicotinamide mononucleotide, from nicotinamide and 5-phosphoribosyl 1-pyrophosphate. The liver, an important organ of NAD metabolism, is thought to release metabolic products such as nicotinamide and may control NAD metabolism in other organs. Moreover, NAD is an important regulator of the circadian rhythm. Liver-specific Nampt-deficient mice and heterozygous Nampt mice have abnormal daily plasma Pi concentration oscillations. These data indicate that NAD metabolism in the intestine, liver, and kidney is closely related to Pi metabolism through the SLC34 family. Here, we review the relationship between the SLC34 family and NAD metabolism based on our recent studies.
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Affiliation(s)
- Sawako Tatsumi
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, 3-18-15 Kuramoto, Tokushima, 770-8503, Japan.,Department of Food Science and Nutrition, School of Human Cultures, The University of Shiga Prefecture, Hikone, Japan
| | - Kanako Katai
- Faculty of Human Life and Science, Department of Food Science and Nutrition, Doshisha Women's College of Liberal Arts, Kyoto, Japan
| | - Ichiro Kaneko
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, 3-18-15 Kuramoto, Tokushima, 770-8503, Japan
| | - Hiroko Segawa
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, 3-18-15 Kuramoto, Tokushima, 770-8503, Japan
| | - Ken-Ichi Miyamoto
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, 3-18-15 Kuramoto, Tokushima, 770-8503, Japan.
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106
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Sasaki S, Segawa H, Hanazaki A, Kirino R, Fujii T, Ikuta K, Noguchi M, Sasaki S, Koike M, Tanifuji K, Shiozaki Y, Kaneko I, Tatsumi S, Shimohata T, Kawai Y, Narisawa S, Millán JL, Miyamoto KI. A Role of Intestinal Alkaline Phosphatase 3 (Akp3) in Inorganic Phosphate Homeostasis. Kidney Blood Press Res 2018; 43:1409-1424. [PMID: 30212831 DOI: 10.1159/000493379] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 08/31/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND/AIMS Hyperphosphatemia is a serious complication of late-stage chronic kidney disease (CKD). Intestinal inorganic phosphate (Pi) handling plays an important role in Pi homeostasis in CKD. We investigated whether intestinal alkaline phosphatase 3 (Akp3), the enzyme that hydrolyzes dietary Pi compounds, is a target for the treatment of hyperphosphatemia in CKD. METHODS We investigated Pi homeostasis in Akp3 knockout mice (Akp3-/-). We also studied the progression of renal failure in an Akp3-/- mouse adenine treated renal failure model. Plasma, fecal, and urinary Pi and Ca concentration were measured with commercially available kit, and plasma fibroblast growth factor 23, parathyroid hormone, and 1,25(OH)2D3 concentration were measured with ELISA. Brush border membrane vesicles were prepared from mouse intestine using the Ca2+ precipitation method and used for Pi transport activity and alkaline phosphatase activity. In vivo intestinal Pi absorption was measured with oral 32P administration. RESULTS Akp3-/- mice exhibited reduced intestinal type II sodium-dependent Pi transporter (Npt2b) protein levels and Na-dependent Pi co-transport activity. In addition, plasma active vitamin D levels were significantly increased in Akp3-/- mice compared with wild-type animals. In the adenine-induced renal failure model, Akp3 gene deletion suppressed hyperphosphatemia. CONCLUSION The present findings indicate that intestinal Akp3 deletion affects Na+-dependent Pi transport in the small intestine. In the adenine-induced renal failure model, Akp3 is predicted to be a factor contributing to suppression of the plasma Pi concentration.
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Affiliation(s)
- Shohei Sasaki
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Hiroko Segawa
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima,
| | - Ai Hanazaki
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Ruri Kirino
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Toru Fujii
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Kayo Ikuta
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Miwa Noguchi
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Sumire Sasaki
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Megumi Koike
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Kazuya Tanifuji
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Yuji Shiozaki
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Ichiro Kaneko
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Sawako Tatsumi
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Takaaki Shimohata
- Department of Preventive Environment and Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Yoshichika Kawai
- Department of Food Science, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
| | - Sonoko Narisawa
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - José Luis Millán
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Ken-Ichi Miyamoto
- Department of Molecular Nutrition, Institute of Biomedical Sciences, University of Tokushima Graduate School, Tokushima, Japan
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107
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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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108
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Boisvert NC, Holterman CE, Gutsol A, Coulombe J, Pan W, Alexander RT, Gray DA, Kennedy CR. Ubiquitin COOH-terminal hydrolase L1 deletion is associated with urinary α-klotho deficiency and perturbed phosphate homeostasis. Am J Physiol Renal Physiol 2018; 315:F353-F363. [DOI: 10.1152/ajprenal.00411.2017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Loss of ubiquitin COOH-terminal hydrolase L1 (UCHL1), a deubiquitinating enzyme required for neuronal function, led to hyperphosphatemia accompanied by phosphaturia in mice, while calcium homeostasis remained intact. We therefore investigated the mechanisms underlying the phosphate imbalance in Uchl1−/− mice. Interestingly, phosphaturia was not a result of lower renal brush border membrane sodium-phosphate cotransporter expression as sodium-phosphate cotransporter 2a and 2c expression levels was similar to wild-type levels. Plasma parathyroid hormone and fibroblast growth factor 23 levels were not different; however, fibroblast growth factor 23 mRNA levels were significantly increased in femur homogenates from Uchl1−/− mice. Full-length and soluble α-klotho levels were comparable in kidneys from wild-type and Uchl1−/− mice; however, soluble α-klotho was reduced in Uchl1−/− mice urine. Consistent with unchanged components of 1,25(OH)2D3 metabolism (i.e., CYP27B1 and CYP24A1), sodium-phosphate cotransporter 2b protein levels were not different in ileum brush borders from Uchl1−/− mice, suggesting that the intestine is not the source of hyperphosphatemia. Nonetheless, when Uchl1−/− mice were fed a low-phosphate diet, plasma phosphate, urinary phosphate, and fractional excretion of phosphate were significantly attenuated and comparable to levels of low-phosphate diet-fed wild-type mice. Our findings demonstrate that Uchl1-deleted mice exhibit perturbed phosphate homeostasis, likely consequent to decreased urinary soluble α-klotho, which can be rescued with a low-phosphate diet. Uchl1−/− mice may provide a useful mouse model to study mild perturbations in phosphate homeostasis.
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Affiliation(s)
- Naomi C. Boisvert
- Kidney Research Centre, The Ottawa Hospital, Ottawa, Ontario, Canada
- Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Chet E. Holterman
- Kidney Research Centre, The Ottawa Hospital, Ottawa, Ontario, Canada
- Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Alexey Gutsol
- Kidney Research Centre, The Ottawa Hospital, Ottawa, Ontario, Canada
- Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Josée Coulombe
- Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
| | - Wanling Pan
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - R. Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
- Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Douglas A. Gray
- Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
- Faculty of Medicine, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Chris R. Kennedy
- Kidney Research Centre, The Ottawa Hospital, Ottawa, Ontario, Canada
- Ottawa Hospital Research Institute, The Ottawa Hospital, Ottawa, Ontario, Canada
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
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109
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Ren ZZ, Bütz DE, Wahhab AN, Piepenburg AJ, Cook ME. Additive effects of fibroblast growth factor 23 neutralization and dietary phytase on chick calcium and phosphorus metabolism. Poult Sci 2018; 96:1167-1173. [PMID: 27665015 DOI: 10.3382/ps/pew339] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 08/11/2016] [Indexed: 01/01/2023] Open
Abstract
Phytase hydrolyzes phytate rendering phosphorus available for intestinal absorption, while systemic neutralization of fibroblast growth factor 23 (FGF-23), using anti-FGF-23 antibody, has been shown to increase phosphate retention. Hence, neutralization of FGF-23 should be additive with phytase in reducing dietary non-phytate phosphorus (nPP) needs in chickens fed plant-based diets rich in phytic acid. This study was designed to test the additive effects of maternally derived anti-FGF-23 antibody and dietary phytase on the performance of chicks fed a low nPP diet from one to 14 d. Single Comb White Leghorn laying hens were vaccinated with either an adjuvant control or a synthetic FGF-23 peptide (GMNPPPYS). Chicks from vaccinated hens with control or anti-FGF-23 maternal antibodies were fed either a diet containing 0.2% nPP and 0.9% calcium with or without 500 unit phytase per kg of diet (2 × 2 factorial with main effects of antibody type and phytase addition, n = 15 pens of chicks/treatment). A significant interaction between dietary phytase and maternally derived anti-FGF-23 antibody on growth and feed efficiency was observed (P ≤ 0.05), in which chicks receiving either phytase or maternally derived anti-FGF-23 antibody had improved body weight gain (21 or 15%, respectively) and feed efficiency (16 or 18%, respectively) as compared to chicks with control antibody and not fed phytase. Both phytase and maternally derived anti-FGF-23 antibody independently increased (P ≤ 0.05) plasma phosphate (11 and 11%, respectively) and percent tibiotarsus ash (13 and 11%, respectively). Significant main effects and the lack of an interaction supported an additive effect of phytase and anti-FGF-23 antibody on plasma phosphate and percent tibiotarsus ash. Feeding phytase to chicks fed 0.2% nPP increased plasma FGF-23 levels by 22% (P ≤ 0.05); however, no effects of anti-FGF-23 antibody on plasma FGF-23 levels were observed. In conclusion, dietary phytase and presence of anti-FGF-23 antibody have an additive effect on plasma phosphate and tibiotarsus ash in chicks fed low nPP diets. Data support that phytase and anti-FGF-23 antibody increase phosphate utilization by different mechanisms.
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Affiliation(s)
- Z Z Ren
- Department of Animal Sciences, 1675 Observatory Drive, University of Wisconsin-Madison 53706.,Institute of Animal Nutrition, 211 Huimin Road, Sichuan Agricultural University, Chengdu, Sichuan 611130, China
| | - D E Bütz
- Department of Animal Sciences, 1675 Observatory Drive, University of Wisconsin-Madison 53706
| | - A N Wahhab
- Department of Animal Sciences, 1675 Observatory Drive, University of Wisconsin-Madison 53706
| | - A J Piepenburg
- Department of Animal Sciences, 1675 Observatory Drive, University of Wisconsin-Madison 53706
| | - M E Cook
- Department of Animal Sciences, 1675 Observatory Drive, University of Wisconsin-Madison 53706
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110
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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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Li P, Wang R, Jiao H, Wang X, Zhao J, Lin H. Effects of Dietary Phosphorus Level on the Expression of Calcium and Phosphorus Transporters in Laying Hens. Front Physiol 2018; 9:627. [PMID: 29910739 PMCID: PMC5992381 DOI: 10.3389/fphys.2018.00627] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 05/09/2018] [Indexed: 12/02/2022] Open
Abstract
The transport of calcium and phosphorus is mainly relied on their corresponding transporters. The aim of this study was to determine the effect of dietary phosphorus level on the expression of the relevant calcium and phosphorus transporters in laying hens, which has a large amount of calcium and phosphorus input from intestine and output from kidney and eggshell gland. Thirty-six 25-week-old Hy-line Brown hens were fed diets with different available phosphorus level (AP, 0.15, 0.41, and 0.82%), respectively. The expression of phosphorus transporters type IIa and type IIb Na/Pi co-transporter (NPt2a, NPt2b), calcium transporter calbindin-D28k (CaBP-D28k), and plasma membrane Ca ATPase 1b (PMCA1b) were measured in small intestine, kidney, and eggshell gland by RT-PCR and western blot. The results showed that serum calcitriol and PTH concentrations were not affected (P > 0.05) by dietary AP levels. Duodenum had the highest mRNA and protein expression level of NPt2b than jejunum and ileum (P < 0.05). The protein expression abundance of CaBP-D28k and PMCA1b were higher in duodenum than that in jejunum and ileum (P < 0.05). 0.15%-AP diet upregulated the ileal mRNA expression level of NPt2b and renal mRNA expression level of NPt2a (P < 0.05), while downregulated the protein abundance of NPt2b and CaBP-D28k mRNA expression in shell gland (P < 0.05). In conclusion, both the Ca and P transporters were highly expressed in duodenum. Low AP diet decreased protein expression abundance of NPt2b in duodenum while upregulated the mRNA expression level of NPt2a in kidney. The result suggests that both the phosphorus absorption in proximal intestine and its reabsorption in kidney are involved in the adaption to low AP diet.
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Affiliation(s)
- Peng Li
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Rongmei Wang
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an, China.,College of Sports Medicine and Rehabilitation, Taishan Medical University, Tai'an, China
| | - Hongchao Jiao
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Xiaojuan Wang
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Jingpeng Zhao
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an, China
| | - Hai Lin
- Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai'an, China
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112
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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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113
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Filipski KJ, Sammons MF, Bhattacharya SK, Panteleev J, Brown JA, Loria PM, Boehm M, Smith AC, Shavnya A, Conn EL, Song K, Weng Y, Facemire C, Jüppner H, Clerin V. Discovery of Orally Bioavailable Selective Inhibitors of the Sodium-Phosphate Cotransporter NaPi2a (SLC34A1). ACS Med Chem Lett 2018; 9:440-445. [PMID: 29795756 DOI: 10.1021/acsmedchemlett.8b00013] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 04/04/2018] [Indexed: 11/30/2022] Open
Abstract
Sodium-phosphate cotransporter 2a, or NaPi2a (SLC34A1), is a solute-carrier (SLC) transporter located in the kidney proximal tubule that reabsorbs glomerular-filtered phosphate. Inhibition of NaPi2a may enhance urinary phosphate excretion and correct maladaptive mineral and hormonal derangements associated with increased cardiovascular risk in chronic kidney disease-mineral and bone disorder (CKD-MBD). To date, only nonselective NaPi inhibitors have been described. Herein, we detail the discovery of the first series of selective NaPi2a inhibitors, resulting from optimization of a high-throughput screening hit. The oral PK profile of inhibitor PF-06869206 (6f) in rodents allows for the exploration of the pharmacology of selective NaPi2a inhibition.
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Affiliation(s)
- Kevin J. Filipski
- Pfizer Worldwide Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Matthew F. Sammons
- Pfizer Worldwide Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Samit K. Bhattacharya
- Pfizer Worldwide Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Jane Panteleev
- Pfizer Worldwide Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Janice A. Brown
- Pfizer Worldwide Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Paula M. Loria
- Pfizer Worldwide Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Markus Boehm
- Pfizer Worldwide Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Aaron C. Smith
- Pfizer Worldwide Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Andre Shavnya
- Pfizer Worldwide Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Edward L. Conn
- Pfizer Worldwide Research & Development, 558 Eastern Point Road, Groton, Connecticut 06340, United States
| | - Kun Song
- Pfizer Worldwide Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Yan Weng
- Pfizer Worldwide Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Carie Facemire
- Pfizer Worldwide Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
| | - Harald Jüppner
- Endocrine Unit and Pediatric Nephrology Unit, Thier 10, Massachusetts General Hospital and Harvard Medical School, 50 Blossom Street, Boston, Massachusetts 02114, United States
| | - Valerie Clerin
- Pfizer Worldwide Research & Development, 1 Portland Street, Cambridge, Massachusetts 02139, United States
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114
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Miyagawa A, Tatsumi S, Takahama W, Fujii O, Nagamoto K, Kinoshita E, Nomura K, Ikuta K, Fujii T, Hanazaki A, Kaneko I, Segawa H, Miyamoto KI. The sodium phosphate cotransporter family and nicotinamide phosphoribosyltransferase contribute to the daily oscillation of plasma inorganic phosphate concentration. Kidney Int 2018; 93:1073-1085. [PMID: 29398136 DOI: 10.1016/j.kint.2017.11.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 11/07/2017] [Accepted: 11/16/2017] [Indexed: 12/31/2022]
Abstract
Circulating inorganic phosphate exhibits a remarkable daily oscillation based on food intake. In humans and rodents, the daily oscillation in response to food intake may be coordinated to control the intestinal absorption, renal excretion, cellular shifts, and extracellular concentration of inorganic phosphate. However, mechanisms regulating the resulting oscillation are unknown. Here we investigated the roles of the sodium phosphate cotransporter SLC34 (Npt2) family and nicotinamide phosphoribosyltransferase (Nampt) in the daily oscillation of plasma inorganic phosphate levels. First, it is roughly linked to urinary inorganic phosphate excretion. Second, expression of renal Npt2a and Npt2c, and intestinal Npt2b proteins also exhibit a dynamic daily oscillation. Analyses of Npt2a, Npt2b, and Npt2c knockout mice revealed the importance of renal inorganic phosphate reabsorption and cellular inorganic phosphate shifts in the daily oscillation. Third, experiments in which nicotinamide and a specific Nampt inhibitor (FK866) were administered in the active and rest phases revealed that the Nampt/NAD+ system is involved in renal inorganic phosphate excretion. Additionally, for cellular shifts, liver-specific Nampt deletion disturbed the daily oscillation of plasma phosphate during the rest but not the active phase. In systemic Nampt+/- mice, NAD levels were significantly reduced in the liver, kidney, and intestine, and the daily oscillation (active and rest phases) of the plasma phosphate concentration was attenuated. Thus, the Nampt/NAD+ system for Npt2 regulation and cellular shifts to tissues such as the liver play an important role in generating daily oscillation of plasma inorganic phosphate levels.
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Affiliation(s)
- Atsumi Miyagawa
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Sawako Tatsumi
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan.
| | - Wako Takahama
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Osamu Fujii
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Kenta Nagamoto
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Emi Kinoshita
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Kengo Nomura
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Kayo Ikuta
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Toru Fujii
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Ai Hanazaki
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Ichiro Kaneko
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Hiroko Segawa
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan
| | - Ken-Ichi Miyamoto
- Department of Molecular Nutrition, Institution of Biomedical Science, Tokushima University Graduate School, Tokushima, Japan.
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Wagener EDA, Souma N, Hodakowski A, Martinez C, Fox P, Mehta R, O'Brien MJ, Bolon M, Kulik L, Yang GY, Isakova T. A Patient With CKD Develops Cholestatic Liver Injury During a Clinical Trial. Kidney Int Rep 2018; 3:5-10. [PMID: 29340307 PMCID: PMC5762939 DOI: 10.1016/j.ekir.2017.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Emma D A Wagener
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Nao Souma
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Alexander Hodakowski
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Carlos Martinez
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Patrick Fox
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Rupal Mehta
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.,Division of Nephrology and Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Matthew J O'Brien
- Division of General Internal Medicine and Geriatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Maureen Bolon
- Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Laura Kulik
- Division of Gastroenterology and Hepatology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Guang-Yu Yang
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Tamara Isakova
- Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.,Division of Nephrology and Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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Abstract
PURPOSE OF REVIEW Higher serum phosphate concentration is a central driver of the chronic kidney disease (CKD) mineral bone disorder (MBD). Although phosphate binders are commonly used to lower phosphate, they are minimally effective in CKD. Nicotinamide (vitamin B3) decreases intestinal phosphate transport in animals. Its efficacy and safety in CKD is uncertain. RECENT FINDINGS We review data differentiating nicotinamide from nicotinic acid (niacin) and compare the metabolism and side-effect profile of each. Several recent studies have tested the safety and efficacy of nicotinamide in patients with CKD and the general population. Available data on efficacy and safety, gaps in knowledge, and ongoing studies to address them are described. SUMMARY Nicotinamide is a novel potential tool to treat hyperphosphatemia in patients with CKD, but additional data on safety and efficacy are required before widespread clinical use.
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117
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Abstract
Rickets is a bone disease associated with abnormal serum calcium and phosphate levels. The clinical presentation is heterogeneous and depends on the age of onset and pathogenesis but includes bowing deformities of the legs, short stature and widening of joints. The disorder can be caused by nutritional deficiencies or genetic defects. Mutations in genes encoding proteins involved in vitamin D metabolism or action, fibroblast growth factor 23 (FGF23) production or degradation, renal phosphate handling or bone mineralization have been identified. The prevalence of nutritional rickets has substantially declined compared with the prevalence 200 years ago, but the condition has been re-emerging even in some well-resourced countries; prematurely born infants or breastfed infants who have dark skin types are particularly at risk. Diagnosis is usually established by medical history, physical examination, biochemical tests and radiography. Prevention is possible only for nutritional rickets and includes supplementation or food fortification with calcium and vitamin D either alone or in combination with sunlight exposure. Treatment of typical nutritional rickets includes calcium and/or vitamin D supplementation, although instances infrequently occur in which phosphate repletion may be necessary. Management of heritable types of rickets associated with defects in vitamin D metabolism or activation involves the administration of vitamin D metabolites. Oral phosphate supplementation is usually indicated for FGF23-independent phosphopenic rickets, whereas the conventional treatment of FGF23-dependent types of rickets includes a combination of phosphate and activated vitamin D; an anti-FGF23 antibody has shown promising results and is under further study.
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118
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Zhang L, Guo X, Zhang L, Yang F, Qin L, Zhang D, Qin Y. SLC34A2 regulates miR-25-Gsk3β signaling pathway to affect tumor progression in gastric cancer stem cell-like cells. Mol Carcinog 2017; 57:440-450. [PMID: 29178392 DOI: 10.1002/mc.22768] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 11/20/2017] [Indexed: 12/18/2022]
Abstract
A novel paradigm in tumor biology suggests that gastric cancer progression is driven by gastric cancer stem cell-like cells (GCSCs), but molecular mechanisms regulating tumorigenic and self-renewal potential of GCSCs are still unclear. Here, we aim to investigate biological function of SLC34A2 in regulating sphere formation and tumorigenicity (both are the hallmark of CSCs) of GCSCs and its underlying mechanisms. Our findings testified that CD44+ cells which were derived from fresh primary gastric cancer samples and cell lines displayed stem cell-like features. Significantly, SLC34A2 is increased in CD44+ GCSCs compared with those in adherent counterpart from CD44+ GCSCs. On clinic, SLC34A2 is overexpressed in primary tumor tissues compared with adjacent counterparts. We showed that SLC34A2 regulated sphere formation and self-renewal properties of CD44+ GCSCs in vitro and in vivo. Mechanistic investigations revealed that Gsk3β was the most strikingly up-regulated gene in response to SLC34A2 knockdown in GCSCs and Wnt/β-cantenin signaling was required for SLC34A2-mediated sphere formation. Furthermore, SLC34A2 directly binds specific sites in the miR-25 promoter region and that the promoter activity is decreased after the mutation of putative SLC34A2-binding sites, indicating that SLC34A2 is required for the transcriptional induction of miR-25. Meanwhile, luciferase assays showed that miR-25 directly targeted Gsk3β in CD44+ GCSCs. Overall, our findings define a SLC34A2-miR-25-Gsk3β pathway in the regulation of GCSCs features and gastric cancer progression, with potential therapeutic applications in blocking their progression.
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Affiliation(s)
- Lanfang Zhang
- Department of Gastroenterology, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan Province, People's Republic of China
| | - Xiaohe Guo
- Department of Gastroenterology, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan Province, People's Republic of China
| | - Lili Zhang
- Department of Gastroenterology, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan Province, People's Republic of China
| | - Fang Yang
- Department of Gastroenterology, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan Province, People's Republic of China
| | - Lei Qin
- Department of Gastroenterology, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan Province, People's Republic of China
| | - Dezhong Zhang
- Department of Gastroenterological Surgery, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan Province, People's Republic of China
| | - Yongmei Qin
- Department of Gastroenterology, The First Affiliated Hospital of Xinxiang Medical University, Weihui, Henan Province, People's Republic of China
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119
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Development and Characterization of a Human and Mouse Intestinal Epithelial Cell Monolayer Platform. Stem Cell Reports 2017; 9:1976-1990. [PMID: 29153987 PMCID: PMC5785676 DOI: 10.1016/j.stemcr.2017.10.013] [Citation(s) in RCA: 118] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 10/13/2017] [Accepted: 10/15/2017] [Indexed: 12/13/2022] Open
Abstract
We describe the development and characterization of a mouse and human epithelial cell monolayer platform of the small and large intestines, with a broad range of potential applications including the discovery and development of minimally systemic drug candidates. Culture conditions for each intestinal segment were optimized by correlating monolayer global gene expression with the corresponding tissue segment. The monolayers polarized, formed tight junctions, and contained a diversity of intestinal epithelial cell lineages. Ion transport phenotypes of monolayers from the proximal and distal colon and small intestine matched the known and unique physiology of these intestinal segments. The cultures secreted serotonin, GLP-1, and FGF19 and upregulated the epithelial sodium channel in response to known biologically active agents, suggesting intact secretory and absorptive functions. A screen of over 2,000 pharmacologically active compounds for inhibition of potassium ion transport in the mouse distal colon cultures led to the identification of a tool compound. Epithelial cell monolayer growth conditions developed for all intestinal segments Monolayer gene expression is consistent with tissue from each intestinal segment Ion transport, secretory, and absorptive functions match intestinal physiology Compound screen identified inhibitor of mouse distal colon potassium transport
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120
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Ikuta K, Segawa H, Sasaki S, Hanazaki A, Fujii T, Kushi A, Kawabata Y, Kirino R, Sasaki S, Noguchi M, Kaneko I, Tatsumi S, Ueda O, Wada NA, Tateishi H, Kakefuda M, Kawase Y, Ohtomo S, Ichida Y, Maeda A, Jishage KI, Horiba N, Miyamoto KI. Effect of Npt2b deletion on intestinal and renal inorganic phosphate (Pi) handling. Clin Exp Nephrol 2017; 22:517-528. [PMID: 29128884 DOI: 10.1007/s10157-017-1497-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 10/13/2017] [Indexed: 12/16/2022]
Abstract
BACKGROUND Hyperphosphatemia is common in chronic kidney disease and is associated with morbidity and mortality. The intestinal Na+-dependent phosphate transporter Npt2b is thought to be an important molecular target for the prevention of hyperphosphatemia. The role of Npt2b in the net absorption of inorganic phosphate (Pi), however, is controversial. METHODS In the present study, we made tamoxifen-inducible Npt2b conditional knockout (CKO) mice to analyze systemic Pi metabolism, including intestinal Pi absorption. RESULTS Although the Na+-dependent Pi transport in brush-border membrane vesicle uptake levels was significantly decreased in the distal intestine of Npt2b CKO mice compared with control mice, plasma Pi and fecal Pi excretion levels were not significantly different. Data obtained using the intestinal loop technique showed that Pi uptake in Npt2b CKO mice was not affected at a Pi concentration of 4 mM, which is considered the typical luminal Pi concentration after meals in mice. Claudin, which may be involved in paracellular pathways, as well as claudin-2, 12, and 15 protein levels were significantly decreased in the Npt2b CKO mice. Thus, Npt2b deficiency did not affect Pi absorption within the range of Pi concentrations that normally occurs after meals. CONCLUSION These findings indicate that abnormal Pi metabolism may also be involved in tight junction molecules such as Cldns that are affected by Npt2b deficiency.
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Affiliation(s)
- Kayo Ikuta
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Hiroko Segawa
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan.
| | - Shohei Sasaki
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Ai Hanazaki
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Toru Fujii
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Aoi Kushi
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Yuka Kawabata
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Ruri Kirino
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Sumire Sasaki
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Miwa Noguchi
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Ichiro Kaneko
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Sawako Tatsumi
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
| | - Otoya Ueda
- Fuji Gotemba Research Labs., Research Division, Chugai Pharmaceutical Co., Ltd., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Naoko A Wada
- Fuji Gotemba Research Labs., Research Division, Chugai Pharmaceutical Co., Ltd., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Hiromi Tateishi
- Chugai Research Institute for Medical Science, Inc., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Mami Kakefuda
- Chugai Research Institute for Medical Science, Inc., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Yosuke Kawase
- Chugai Research Institute for Medical Science, Inc., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Shuichi Ohtomo
- Fuji Gotemba Research Labs., Research Division, Chugai Pharmaceutical Co., Ltd., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Yasuhiro Ichida
- Fuji Gotemba Research Labs., Research Division, Chugai Pharmaceutical Co., Ltd., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Akira Maeda
- Fuji Gotemba Research Labs., Research Division, Chugai Pharmaceutical Co., Ltd., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Kou-Ichi Jishage
- Fuji Gotemba Research Labs., Research Division, Chugai Pharmaceutical Co., Ltd., 1-135, Komakado, Gotemba, Shizuoka, Japan
- Chugai Research Institute for Medical Science, Inc., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Naoshi Horiba
- Fuji Gotemba Research Labs., Research Division, Chugai Pharmaceutical Co., Ltd., 1-135, Komakado, Gotemba, Shizuoka, Japan
| | - Ken-Ichi Miyamoto
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-Cho, Tokushima, Tokushima, 770-8503, Japan
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121
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Targeted Pth4-expressing cell ablation impairs skeletal mineralization in zebrafish. PLoS One 2017; 12:e0186444. [PMID: 29040309 PMCID: PMC5645135 DOI: 10.1371/journal.pone.0186444] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 10/02/2017] [Indexed: 12/20/2022] Open
Abstract
Skeletal development and mineralization are essential processes driven by the coordinated action of neural signals, circulating molecules and local factors. Our previous studies revealed that the novel neuropeptide Pth4, synthesized by hypothalamic cells, was involved in bone metabolism via phosphate regulation in adult zebrafish. Here, we investigate the role of pth4 during skeletal development using single-cell resolution, two-photon laser ablation of Pth4:eGFP-expressing cells and confocal imaging in vivo. Using a stable transgenic Pth4:eGFP zebrafish line, we identify Pth4:eGFP-expressing cells as post-mitotic neurons. After targeted ablation of eGFP-expressing cells in the hypothalamus, the experimental larvae exhibited impaired mineralization of the craniofacial bones whereas cartilage development was normal. In addition to a decrease in pth4 transcript levels, we noted altered expression of phex and entpd5, genes associated with phosphate homeostasis and mineralization, as well as a delay in the expression of osteoblast differentiation markers such as sp7 and sparc. Taken together, these results suggest that Pth4-expressing hypothalamic neurons participate in the regulation of bone metabolism, possibly through regulating phosphate balance during zebrafish development.
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122
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The intestinal phosphate transporter NaPi-IIb (Slc34a2) is required to protect bone during dietary phosphate restriction. Sci Rep 2017; 7:11018. [PMID: 28887454 PMCID: PMC5591270 DOI: 10.1038/s41598-017-10390-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 08/07/2017] [Indexed: 02/04/2023] Open
Abstract
NaPi-IIb/Slc34a2 is a Na+-dependent phosphate transporter that accounts for the majority of active phosphate transport into intestinal epithelial cells. Its abundance is regulated by dietary phosphate, being high during dietary phosphate restriction. Intestinal ablation of NaPi-IIb in mice leads to increased fecal excretion of phosphate, which is compensated by enhanced renal reabsorption. Here we compared the adaptation to dietary phosphate of wild type (WT) and NaPi-IIb−/− mice. High phosphate diet (HPD) increased fecal and urinary excretion of phosphate in both groups, though NaPi-IIb−/− mice still showed lower urinary excretion than WT. In both genotypes low dietary phosphate (LDP) resulted in reduced fecal excretion and almost undetectable urinary excretion of phosphate. Consistently, the expression of renal cotransporters after prolonged LDP was similar in both groups. Plasma phosphate declined more rapidly in NaPi-IIb−/− mice upon LDP, though both genotypes had comparable levels of 1,25(OH)2vitamin D3, parathyroid hormone and fibroblast growth factor 23. Instead, NaPi-IIb−/− mice fed LDP had exacerbated hypercalciuria, higher urinary excretion of corticosterone and deoxypyridinoline, lower bone mineral density and higher number of osteoclasts. These data suggest that during dietary phosphate restriction NaPi-IIb-mediated intestinal absorption prevents excessive demineralization of bone as an alternative source of phosphate.
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Osmolality of Orally Administered Solutions Influences Luminal Water Volume and Drug Absorption in Intestine. J Pharm Sci 2017; 106:2889-2894. [DOI: 10.1016/j.xphs.2017.04.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/14/2017] [Accepted: 04/17/2017] [Indexed: 12/14/2022]
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124
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Larsson TE, Kameoka C, Nakajo I, Taniuchi Y, Yoshida S, Akizawa T, Smulders RA. NPT-IIb Inhibition Does Not Improve Hyperphosphatemia in CKD. Kidney Int Rep 2017; 3:73-80. [PMID: 29340316 PMCID: PMC5762974 DOI: 10.1016/j.ekir.2017.08.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/04/2017] [Accepted: 08/07/2017] [Indexed: 01/19/2023] Open
Abstract
Introduction Serum phosphate levels are insufficiently controlled in many patients with end-stage renal disease (ESRD), and novel therapeutic strategies are needed. Blocking intestinal phosphate absorption mediated by sodium-dependent phosphate co-transporter type 2b (NPT-IIb) holds promise; thus, we evaluated the efficacy, safety, tolerability, and pharmacokinetics of the novel and specific small molecule NPT-IIb inhibitor ASP3325 for the first time in humans. Methods We conducted a randomized, double-blind, placebo-controlled, phase 1a single (n = 88) and multiple (n = 36) ascending dose study in healthy subjects, and a randomized, open-label, uncontrolled, phase 1b study in hyperphosphatemic ESRD patients on hemodialysis (single oral dose, n = 5; multiple oral doses, n = 17). Primary efficacy measures were urinary phosphate and fecal phosphorous excretion (healthy subjects) and serum phosphate level (ESRD patients). Results No time- or dose-dependent changes in urinary phosphate or fecal phosphorous excretion were observed following single/multiple ASP3325 doses for 7 days in healthy subjects. In ESRD patients, ASP3325 administered 3 times daily for 2 weeks before or after a meal did not reduce serum phosphate levels. ASP3325 was safe and well tolerated in both populations. Conclusion NPT-IIb inhibition with ASP3325 was not effective in reducing serum phosphate levels in ESRD patients. The relevance of NPT-IIb in humans and feasibility of oral NPT-IIb inhibitors for treatment of hyperphosphatemia in ESRD remain uncertain.
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Affiliation(s)
| | | | | | | | | | - Tadao Akizawa
- Department of Nephrology, Showa University School of Medicine, Tokyo, Japan
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125
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Sugihara K, Masuda M, Nakao M, Abuduli M, Imi Y, Oda N, Okahisa T, Yamamoto H, Takeda E, Taketani Y. Dietary phosphate exacerbates intestinal inflammation in experimental colitis. J Clin Biochem Nutr 2017; 61:91-99. [PMID: 28955125 PMCID: PMC5612814 DOI: 10.3164/jcbn.16-117] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 12/26/2016] [Indexed: 12/31/2022] Open
Abstract
The recent widespread consumption of Western diets and food additives worldwide is associated with excessive inorganic phosphate intake. However, researchers have known little about the impact of dietary phosphate intake on the development of inflammatory bowel disease to date. In this study, we investigated the effects of dietary phosphate on intestinal inflammation in experimental colitis. Sprague-Dawley rats were fed different phosphate diets (0.5%, 1.0% and 1.5% phosphate) with or without dextran sulfate sodium. For in vitro study, the effects of phosphate on proinflammatory cytokine induction and reactive oxygen species production in RAW264.7 macrophage were examined. Dietary phosphate exacerbated intestinal inflammation in experimental colitis in a dose-dependent manner, as assessed by the clinical disease activity score, colon length, and histology. Furthermore, the high phosphate diet increased myeloperoxidase activity and proinflammatory cytokine mRNA expression through the activation of nuclear factor κB in the inflamed colon. In addition, high phosphate loading in RAW264.7 cells directly enhanced reactive oxygen species production and proinflammatory cytokine gene expression. Our results demonstrated that the high phosphate diet exacerbated intestinal inflammation in experimental colitis. These findings have important therapeutic implications for inflammatory bowel disease patients.
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Affiliation(s)
- Kohei Sugihara
- Departments of Clinical Nutrition and Food Management, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Masashi Masuda
- Departments of Clinical Nutrition and Food Management, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Mari Nakao
- Departments of Clinical Nutrition and Food Management, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Maerjianghan Abuduli
- Departments of Clinical Nutrition and Food Management, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Yukiko Imi
- Departments of Clinical Nutrition and Food Management, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Naoko Oda
- Departments of Clinical Nutrition and Food Management, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Toshiya Okahisa
- Department of Gastroenterology and Oncology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Hironori Yamamoto
- Department of Health and Nutrition, Faculty of Human Life, Jin-ai University, Fukui 915-8586, Japan
| | - Eiji Takeda
- Departments of Clinical Nutrition and Food Management, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Yutaka Taketani
- Departments of Clinical Nutrition and Food Management, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
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126
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Minisola S, Peacock M, Fukumoto S, Cipriani C, Pepe J, Tella SH, Collins MT. Tumour-induced osteomalacia. Nat Rev Dis Primers 2017; 3:17044. [PMID: 28703220 DOI: 10.1038/nrdp.2017.44] [Citation(s) in RCA: 188] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Tumour-induced osteomalacia (TIO), also known as oncogenic osteomalacia, is a rare paraneoplastic disorder caused by tumours that secrete fibroblast growth factor 23 (FGF23). Owing to the role of FGF23 in renal phosphate handling and vitamin D synthesis, TIO is characterized by decreased renal tubular reabsorption of phosphate, by hypophosphataemia and by low levels of active vitamin D. Chronic hypophosphataemia ultimately results in osteomalacia (that is, inadequate bone mineralization). The diagnosis of TIO is usually suspected when serum phosphate levels are chronically low in the setting of bone pain, fragility fractures and muscle weakness. Locating the offending tumour can be very difficult, as the tumour is often very small and can be anywhere in the body. Surgical removal of the tumour is the only definitive treatment. When the tumour cannot be located or when complete resection is not possible, medical treatment with phosphate salts or active vitamin D is necessary. One of the most promising emerging treatments for unresectable tumours that cause TIO is the anti-FGF23 monoclonal antibody KRN23. The recent identification of a fusion of fibronectin and fibroblast growth factor receptor 1 (FGFR1) as a molecular driver in some tumours not only sheds light on the pathophysiology of TIO but also opens the door to a better understanding of the transcription, translocation, post-translational modification and secretion of FGF23, as well as suggesting approaches to targeted therapy. Further study will reveal if the FGFR1 pathway is also involved in tumours that do not harbour the translocation.
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Affiliation(s)
- Salvatore Minisola
- Department of Internal Medicine and Medical Disciplines, Sapienza University of Rome, Viale del Policlinico 155, 00161 Rome, Italy
| | - Munro Peacock
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Seijii Fukumoto
- Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Cristiana Cipriani
- Department of Internal Medicine and Medical Disciplines, Sapienza University of Rome, Viale del Policlinico 155, 00161 Rome, Italy
| | - Jessica Pepe
- Department of Internal Medicine and Medical Disciplines, Sapienza University of Rome, Viale del Policlinico 155, 00161 Rome, Italy
| | - Sri Harsha Tella
- Section on Skeletal Disorders and Mineral Homeostasis, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA.,Endocrinology and Metabolism, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Michael T Collins
- Section on Skeletal Disorders and Mineral Homeostasis, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA
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Abstract
Although phosphorus is an essential nutrient required for multiple physiological functions, recent research raises concerns that high phosphorus intake could have detrimental effects on health. Phosphorus is abundant in the food supply of developed countries, occurring naturally in protein-rich foods and as an additive in processed foods. High phosphorus intake can cause vascular and renal calcification, renal tubular injury, and premature death in multiple animal models. Small studies in human suggest that high phosphorus intake may result in positive phosphorus balance and correlate with renal calcification and albuminuria. Although serum phosphorus is strongly associated with cardiovascular disease, progression of kidney disease, and death, limited data exist linking high phosphorus intake directly to adverse clinical outcomes. Further prospective studies are needed to determine whether phosphorus intake is a modifiable risk factor for kidney disease.
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Affiliation(s)
- Alex R Chang
- Kidney Health Research Institute, Geisinger Health System, Danville, Pennsylvania 17822; .,Department of Epidemiology and Health Services Research, Geisinger Health System, Geisinger Health System, Danville, Pennsylvania 17822
| | - Cheryl Anderson
- Division of Preventive Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093
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128
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Lv Y, Wang T, Fan J, Zhang Z, Zhang J, Xu C, Li Y, Zhao G, He C, Meng H, Yang H, Wang Z, Liu J, Chen J, Wang L. The effects and mechanisms of SLC34A2 on maintaining stem cell-like phenotypes in CD147 + breast cancer stem cells. Tumour Biol 2017; 39:1010428317695927. [PMID: 28381172 DOI: 10.1177/1010428317695927] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The cancer stem cell (CSC) hypothesis has gained significant recognition in describing tumorigenesis. Identification of the factors critical to development of breast cancer stem cells (BCSCs) may provide insight into the improvement of effective therapies against breast cancer. In this study, we aim to investigate the biological function of SLC34A2 in affecting the stem cell-like phenotypes in BCSCs and its underlying mechanisms. We demonstrated that CD147+ cells from breast cancer tissue samples and cell lines possessed BCSC-like features, including the ability of self-renewal in vitro, differentiation, and tumorigenic potential in vivo. Flow cytometry analysis showed the presence of a variable fraction of CD147+ cells in 9 of 10 tumor samples. Significantly, SLC34A2 expression in CD147+ BCSCs was enhanced compared with that in differentiated adherent progeny of CD147+ BCSCs and adherently cultured cell line cells. In breast cancer patient cohorts, SLC34A2 expression was found increased in 9 of 10 tumor samples. By using lentiviral-based approach, si-SLC34A2-transduced CD147+ BCSCs showed decreased ability of sphere formation, cell viability in vitro, and tumorigenicity in vivo, which suggested the essential role of SLC34A2 in CD147+ BCSCs. Furthermore, PI3K/AKT pathway and SOX2 were found necessary to maintain the stemness of CD147+ BCSCs by using LY294002 or lentiviral-si-SOX2. Finally, we indicated that SLC34A2 could regulate SOX2 to maintain the stem cell-like features in CD147+ BCSCs through PI3K/AKT pathway. Therefore, our report identifies a novel role of SLC34A2 in BCSCs' state regulation and establishes a rationale for targeting the SLC34A2/PI3K/AKT/SOX2 signaling pathway for breast cancer therapy.
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Affiliation(s)
- Yonggang Lv
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Ting Wang
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Jing Fan
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Zhenzhen Zhang
- 2 Biotecan Medical Diagnostics Co. Ltd., Zhangjiang Center for Translational Medicine, Shanghai, People's Republic of China
| | - Juliang Zhang
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Cheng Xu
- 2 Biotecan Medical Diagnostics Co. Ltd., Zhangjiang Center for Translational Medicine, Shanghai, People's Republic of China
| | - Yongping Li
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Ge Zhao
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Chenyang He
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Huimin Meng
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Hua Yang
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Zhen Wang
- 3 Department of Orthopaedic, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Jiayun Liu
- 4 Institute of Clinical Laboratory Medicine, Xijing Hospital, Fourth Military Medical University, Xi' an, People's Republic of China
| | - Jianghao Chen
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
| | - Ling Wang
- 1 Department of Vascular and Endocrine Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, People's Republic of China
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Candeal E, Caldas YA, Guillén N, Levi M, Sorribas V. Intestinal phosphate absorption is mediated by multiple transport systems in rats. Am J Physiol Gastrointest Liver Physiol 2017; 312:G355-G366. [PMID: 28232455 DOI: 10.1152/ajpgi.00244.2016] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 01/30/2017] [Accepted: 02/04/2017] [Indexed: 01/31/2023]
Abstract
Apical inorganic phosphate (Pi) transport in the small intestine seems to be mainly mediated by the sodium/Pi cotransporter NaPi2b. To verify this role, we have studied the combined effects of pH, phosphonoformate, and Pi deprivation on intestinal Pi transport. Rats were fed, ad libitum, three fodders containing 1.2, 0.6, or 0.1% Pi for 1, 5, or 10 days. Pi deprivation (0.1%) increased both sodium-activated and sodium-independent Pi transport in brush-border membrane vesicles from the duodenum and jejunum for all three times. Alkaline pH inhibited Pi transport, despite the increasing concentration of [Formula: see text] (NaPi2b substrate), whereas acidity increased transport when the concentration of the PiT1/PiT2 substrate, [Formula: see text], was at its highest. The effect of Pi deprivation was maximal at acid pH, but both basal and upregulated transport were inhibited (70%) with phosphonoformate, an inhibitor of NaPi2b. PiT2 and NaPi2b protein abundance increased after 24 h of Pi deprivation in the duodenum, jejunum, and ileum, whereas PiT1 required 5-10 days in the duodenum and jejunum. Therefore, whereas transporter expressions are partially correlated with Pi transport adaptation, the pH effect precludes NaPi2b, and phosphonoformic acid precludes PiT1 and PiT2 as the main transporters. Transport and transporter expression were also inconsistent when feeding was limited to 4 h daily, because the 1.2% Pi diet paradoxically increased Pi transport in the duodenum and jejunum, but NaPi2b and PiT1 expressions only increased with the 0.1% diet. These findings suggest the presence of a major transporter that carries [Formula: see text] and is inhibited by phosphonoformate.NEW & NOTEWORTHY The combined effects of dietary inorganic phosphate (Pi) content, pH, and phosphonoformate inhibition suggest that the resulting apical Pi transport in the small intestine cannot be fully explained by the presence of NaPi2b, PiT1, or PiT2. We provide evidence of the presence of a new sodium-coupled Pi transporter that uses [Formula: see text] as the preferred substrate and is inhibited by phosphonoformate, and its expression correlates with Pi transport in all assayed conditions.
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Affiliation(s)
- Eduardo Candeal
- Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and
| | - Yupanqui A Caldas
- Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and.,Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Natalia Guillén
- Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and
| | - Moshe Levi
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Víctor Sorribas
- Department of Toxicology, University of Zaragoza, Zaragoza, Spain; and
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Lee GJ, Mossa-Al Hashimi L, Debnam ES, Unwin RJ, Marks J. Postprandial adjustments in renal phosphate excretion do not involve a gut-derived phosphaturic factor. Exp Physiol 2017; 102:462-474. [PMID: 28130860 DOI: 10.1113/ep086062] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 01/16/2017] [Indexed: 12/20/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does a previously hypothesized signalling mechanism, believed to detect postprandial increases in intestinal phosphate and that can stimulate the kidneys to rapidly excrete phosphate, operate under physiological conditions? What is the main finding and its importance? Contrary to earlier reports, rapid signalling between the small intestine and kidney mediated by a gut-derived phosphaturic factor in response to a physiological intestinal phosphate load is not supported by the present findings; moreover, hyperphosphataemia and increased parathyroid hormone concentrations are likely to be the underlying factors responsible for the phosphaturia following a supraphysiological intestinal phosphate load. To date, the role of the small intestine in the regulation of postprandial phosphate homeostasis has remained unclear and controversial. Previous studies have proposed the presence of a gut-derived phosphaturic factor that acts independently of changes in plasma phosphate concentration or parathyroid hormone (PTH) concentration; however, these early studies used duodenal luminal phosphate concentrations in the molar range, and therefore, the physiological relevance of this is uncertain. In the present study, we used both in vivo and in vitro approaches to investigate the presence of this putative 'intestinal phosphatonin'. Instillation of 1.3 m phosphate into the duodenum rapidly induced phosphaturia, but in contrast to previous reports, this was associated with significant hyperphosphataemia and elevated PTH concentration; however, there was not the expected decrease in abundance of the renal sodium-phosphate cotransporter NaPi-IIa. Instillation of a physiological (10 mm) phosphate load had no effect on plasma phosphate concentration, PTH concentration or phosphate excretion. Moreover, phosphate uptake by opossum kidney cells was unaffected after incubation with serosal fluid collected from intestinal segments perfused with different concentrations of phosphate. Taken together, these findings do not support the concept of a gut-derived phosphaturic factor that can mediate rapid signalling between the gut and kidney, leading to increased urinary phosphate excretion, as part of normal phosphate homeostasis.
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Affiliation(s)
- Grace J Lee
- Centre for Nephrology, University College London, London, NW3 2PF, UK
| | - Lina Mossa-Al Hashimi
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, NW3 2PF, UK
| | - Edward S Debnam
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, NW3 2PF, UK
| | - Robert J Unwin
- Centre for Nephrology, University College London, London, NW3 2PF, UK.,Department of Neuroscience, Physiology and Pharmacology, University College London, London, NW3 2PF, UK
| | - Joanne Marks
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, NW3 2PF, UK
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131
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Sanchez CP, Mohan S. Genetic Knockout and Rescue Studies in Mice Unravel Abnormal Phosphorus Threshold in Hypophosphatemic Rickets. Endocrinology 2017; 158:455-457. [PMID: 28430915 PMCID: PMC5460786 DOI: 10.1210/en.2017-00030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 01/11/2017] [Indexed: 11/19/2022]
Affiliation(s)
| | - Subburaman Mohan
- Medicine, and
- Orthopedics, Loma Linda University, Loma Linda, California 92354; and
- Musculoskeletal Disease Center, VA Loma Linda Healthcare System, Loma Linda, California 92357
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132
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Ren Z, Ebrahimi M, Bütz DE, Sand JM, Zhang K, Cook ME. Antibody to fibroblast growth factor 23-peptide reduces excreta phosphorus of laying hens. Poult Sci 2017; 96:127-134. [DOI: 10.3382/ps/pew189] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 01/23/2016] [Accepted: 04/19/2016] [Indexed: 12/25/2022] Open
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133
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Kuczera P, Adamczak M, Wiecek A. Fibroblast Growth Factor-23-A Potential Uremic Toxin. Toxins (Basel) 2016; 8:toxins8120369. [PMID: 27941640 PMCID: PMC5198563 DOI: 10.3390/toxins8120369] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 11/30/2016] [Accepted: 12/01/2016] [Indexed: 12/25/2022] Open
Abstract
Fibroblast growth factor-23 (FGF23) is a circulating member of the FGF family produced mainly by the osteocytes and osteoblasts that can act as a hormone. The main action of FGF23 is to lower phosphatemia via the reduction of urinary phosphate reabsorption and the decrease of 1,25(OH)2-D generation in the kidney. In the course of chronic kidney disease (CKD), plasma FGF23 concentration rises early, most probably to compensate the inability of the deteriorating kidneys to excrete an adequate amount of phosphate. However, this comes at the cost of FGF23-related target organ toxicity. Results of clinical studies suggest that elevated plasma FGF23 concentration is independently associated with the increased risk of CKD progression, occurrence of cardio-vascular complications, and mortality in different stages of CKD. FGF23 also contributes to cardiomyocyte hypertrophy, vascular calcification, and endothelial dysfunction. The impact of FGF23 on heart muscle is not dependent on Klotho, but rather on the PLCγ–calcineurin–NFAT (nuclear factor of activated T-cells) pathway. Among the factors increasing plasma FGF23 concentration, active vitamin D analogues play a significant role. Additionally, inflammation and iron deficiency can contribute to the increase of plasma FGF23. Among the factors decreasing plasma FGF23, dietary phosphate restriction, some intestinal phosphate binders, cinacalcet (and other calcimimetics), and nicotinamide can be enumerated. Anti-FGF23 antibodies have also recently been developed to inhibit the action of FGF23 in target organs. Still, the best way to normalize plasma FGF23 in maintenance hemodialysis patients is restoring kidney function by successful kidney transplantation.
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Affiliation(s)
- Piotr Kuczera
- Department of Nephrology, Transplantation and Internal Medicine, Medical University of Silesia, Katowice 40-027, Poland.
| | - Marcin Adamczak
- Department of Nephrology, Transplantation and Internal Medicine, Medical University of Silesia, Katowice 40-027, Poland.
| | - Andrzej Wiecek
- Department of Nephrology, Transplantation and Internal Medicine, Medical University of Silesia, Katowice 40-027, Poland.
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134
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Dominguez Rieg JA, de la Mora Chavez S, Rieg T. Novel developments in differentiating the role of renal and intestinal sodium hydrogen exchanger 3. Am J Physiol Regul Integr Comp Physiol 2016; 311:R1186-R1191. [PMID: 27733387 DOI: 10.1152/ajpregu.00372.2016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 09/22/2016] [Accepted: 10/05/2016] [Indexed: 11/22/2022]
Abstract
The Na+/H+ exchanger isoform 3 (NHE3) facilitates Na+ absorption and H+ secretion and is expressed in the intestine, proximal tubule, and thick ascending limb of the kidney. While the function of NHE3 for Na+ and [Formula: see text](re)absorption has been defined using conventional NHE3 knockout mice (NHE3-/-), the recent generation of conditional NHE3 knockout mice started to give critical new insight into the role of this protein by allowing for temporal and spatial control of NHE3 expression. For example, in contrast to NHE3-/- mice, knockout of NHE3 in the S1 and S2 segments of the proximal tubule or along the entire tubule/collecting duct does not cause any lethality. Nonabsorbable NHE3 inhibitors have been developed, and preclinical as well as clinical trials indicate possible pharmacological use in fluid overload, hypertension, chronic kidney disease, hyperphosphatemia, and constipation. Some of the therapeutic considerations seem to be directly related to the pharmacodynamic properties of these drugs; however, little is known about the effects of these nonabsorbable NHE3 inhibitors on intestinal phosphate transport and the mechanisms so far remain elusive. This review focuses on novel findings of NHE3 in the intestine and the kidney as well as novel drug developments targeting NHE3.
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Affiliation(s)
- Jessica A Dominguez Rieg
- Department of Basic Sciences, Bastyr University California, San Diego, California.,Veterans Affairs San Diego Healthcare System, San Diego, California; and
| | | | - Timo Rieg
- Veterans Affairs San Diego Healthcare System, San Diego, California; and .,Division of Nephrology-Hypertension, Department of Medicine, University of California San Diego, La Jolla, California
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135
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Saito A, Nikolaidis NM, Amlal H, Uehara Y, Gardner JC, LaSance K, Pitstick LB, Bridges JP, Wikenheiser-Brokamp KA, McGraw DW, Woods JC, Sabbagh Y, Schiavi SC, Altinişik G, Jakopović M, Inoue Y, McCormack FX. Modeling pulmonary alveolar microlithiasis by epithelial deletion of the Npt2b sodium phosphate cotransporter reveals putative biomarkers and strategies for treatment. Sci Transl Med 2016; 7:313ra181. [PMID: 26560359 DOI: 10.1126/scitranslmed.aac8577] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Pulmonary alveolar microlithiasis (PAM) is a rare, autosomal recessive lung disorder associated with progressive accumulation of calcium phosphate microliths. Inactivating mutations in SLC34A2, which encodes the NPT2b sodium-dependent phosphate cotransporter, has been proposed as a cause of PAM. We show that epithelial deletion of Npt2b in mice results in a progressive pulmonary process characterized by diffuse alveolar microlith accumulation, radiographic opacification, restrictive physiology, inflammation, fibrosis, and an unexpected alveolar phospholipidosis. Cytokine and surfactant protein elevations in the alveolar lavage and serum of PAM mice and confirmed in serum from PAM patients identify serum MCP-1 (monocyte chemotactic protein 1) and SP-D (surfactant protein D) as potential biomarkers. Microliths introduced by adoptive transfer into the lungs of wild-type mice produce marked macrophage-rich inflammation and elevation of serum MCP-1 that peaks at 1 week and resolves at 1 month, concomitant with clearance of stones. Microliths isolated by bronchoalveolar lavage readily dissolve in EDTA, and therapeutic whole-lung EDTA lavage reduces the burden of stones in the lungs. A low-phosphate diet prevents microlith formation in young animals and reduces lung injury on the basis of reduction in serum SP-D. The burden of pulmonary calcium deposits in established PAM is also diminished within 4 weeks by a low-phosphate diet challenge. These data support a causative role for Npt2b in the pathogenesis of PAM and the use of the PAM mouse model as a preclinical platform for the development of biomarkers and therapeutic strategies.
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Affiliation(s)
- Atsushi Saito
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The University of Cincinnati, Cincinnati, OH 45267, USA
| | - Nikolaos M Nikolaidis
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The University of Cincinnati, Cincinnati, OH 45267, USA
| | - Hassane Amlal
- Department of Internal Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Yasuaki Uehara
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The University of Cincinnati, Cincinnati, OH 45267, USA
| | - Jason C Gardner
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The University of Cincinnati, Cincinnati, OH 45267, USA
| | - Kathleen LaSance
- Vontz Core Imaging Laboratory, Vontz Center for Molecular Studies, The University of Cincinnati, Cincinnati, OH 45267, USA
| | - Lori B Pitstick
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The University of Cincinnati, Cincinnati, OH 45267, USA
| | - James P Bridges
- Perinatal Institute, Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | | | - Dennis W McGraw
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The University of Cincinnati, Cincinnati, OH 45267, USA
| | - Jason C Woods
- Pulmonary Imaging Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Yves Sabbagh
- The Sanofi-Genzyme R&D Center, Genzyme, a Sanofi company, Framingham, MA 01701, USA
| | - Susan C Schiavi
- The Sanofi-Genzyme R&D Center, Genzyme, a Sanofi company, Framingham, MA 01701, USA
| | - Göksel Altinişik
- Department of Chest Diseases, Faculty of Medicine, Pamukkale University, Denizli 20160, Turkey
| | - Marko Jakopović
- Department for Respiratory Diseases, University Hospital Centre Zagreb, University of Zagreb School of Medicine, 10000 Zagreb, Croatia
| | - Yoshikazu Inoue
- Department of Diffuse Lung Diseases and Respiratory Failure, Clinical Research Center, National Hospital Organization Kinki-Chuo Chest Medical Center, Osaka 5918555, Japan
| | - Francis X McCormack
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, The University of Cincinnati, Cincinnati, OH 45267, USA.
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136
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Fang RJ, Xiang ZF, Hu LC, Su WQ, Tang XP, Wang XR. Effects of mechanistic target of rapamycin signaling pathway on the estrogen-mediated NaPi-IIb protein expression in pig small intestinal epithelial cells1. J Anim Sci 2016. [DOI: 10.2527/jas.2015-9866] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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137
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Affiliation(s)
- K Sampathkumar
- Department of Nephrology, Meenakshi Mission Hospital and Research Centre, Madurai, Tamil Nadu, India
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138
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Wu‐Wong JR, Chen Y, Wong JT, Wessale JL. Preclinical studies of VS-505: a non-absorbable highly effective phosphate binder. Br J Pharmacol 2016; 173:2278-89. [PMID: 27156057 PMCID: PMC4919576 DOI: 10.1111/bph.13510] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 04/16/2016] [Accepted: 04/22/2016] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND PURPOSE Phosphate imbalance is often present in chronic kidney disease (CKD), and it contributes to a higher cardiovascular mortality rate. A phosphate binder is typically part of a treatment strategy for controlling phosphate imbalance. However, safety concerns and low compliance are two well-recognized disadvantages of on-market phosphate binders. This report describes the preclinical studies of VS-505, a non-absorbable, calcium- and aluminum-free, plant-derived polymer currently being evaluated in haemodialysis patients in Australia. EXPERIMENTAL APPROACH Normal Sprague Dawley (SD) rats or uraemic SD rats induced by 5/6 nephrectomy fed a high-phosphate diet were treated with VS-505 or sevelamer (0.05-10% in food) for 5 and 28 days respectively. KEY RESULTS Urinary and serum phosphate levels were significantly elevated in untreated rats, and were decreased by VS-505 and sevelamer. VS-505 increased faecal phosphate levels in a dose-dependent manner. High-phosphate diet also caused an increase in serum FGF-23 and parathyroid hormone in nephrectomized (NX) rats, effects prevented by VS-505 or sevelamer. Significant aortic calcification was observed in NX rats treated with 5% sevelamer, whereas VS-505 at all doses tested did not show effects. VS-505 had no effects on small intestine histomorphology and intestinal sodium-dependent phosphate cotransporter gene expression. In vitro characterizations showed that VS-505 has a relatively high density and low expansion volume when exposed to simulated gastric fluid. CONCLUSIONS AND IMPLICATIONS VS-505 is a safe and effective phosphate binder and may offer the advantage of having a reduced pill burden and minimal GI side effects for CKD patients.
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Abstract
Pulmonary alveolar microlithiasis (PAM) is a genetic lung disorder that is characterized by the accumulation of calcium phosphate deposits in the alveolar spaces of the lung. Mutations in the type II sodium phosphate cotransporter, NPT2b, have been reported in patients with PAM. PAM progresses gradually, often producing incremental dyspnea on exertion, desaturation in young adulthood, and respiratory insufficiency by late middle age. Treatment remains supportive, including supplemental oxygen therapy. For patients with end-stage disease, lung transplantation is available as a last resort. The recent development of a laboratory animal model has revealed several promising treatment approaches for future trials.
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140
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Komaba H, Fukagawa M. Phosphate-a poison for humans? Kidney Int 2016; 90:753-63. [PMID: 27282935 DOI: 10.1016/j.kint.2016.03.039] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 03/03/2016] [Accepted: 03/24/2016] [Indexed: 02/07/2023]
Abstract
Maintenance of phosphate balance is essential for life, and mammals have developed a sophisticated system to regulate phosphate homeostasis over the course of evolution. However, due to the dependence of phosphate elimination on the kidney, humans with decreased kidney function are likely to be in a positive phosphate balance. Phosphate excess has been well recognized as a critical factor in the pathogenesis of mineral and bone disorders associated with chronic kidney disease, but recent investigations have also uncovered toxic effects of phosphate on the cardiovascular system and the aging process. Compelling evidence also suggests that increased fibroblastic growth factor 23 and parathyroid hormone levels in response to a positive phosphate balance contribute to adverse clinical outcomes. These insights support the current practice of managing serum phosphate in patients with advanced chronic kidney disease, although definitive evidence of these effects is lacking. Given the potential toxicity of excess phosphate, the general population may also be viewed as a target for phosphate management. However, the widespread implementation of dietary phosphate intervention in the general population may not be warranted due to the limited impact of increased phosphate intake on mineral metabolism and clinical outcomes. Nonetheless, the increasing incidence of kidney disease or injury in our aging society emphasizes the potential importance of this issue. Further work is needed to more completely characterize phosphate toxicity and to establish the optimal therapeutic strategy for managing phosphate in patients with chronic kidney disease and in the general population.
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Affiliation(s)
- Hirotaka Komaba
- Division of Nephrology, Endocrinology and Metabolism, Tokai University School of Medicine, Isehara, Japan; Interactive Translational Research Center for Kidney Diseases, Tokai University School of Medicine, Isehara, Japan; The Institute of Medical Sciences, Tokai University, Isehara, Japan
| | - Masafumi Fukagawa
- Division of Nephrology, Endocrinology and Metabolism, Tokai University School of Medicine, Isehara, Japan.
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141
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Abstract
Maintenance of a normal serum phosphate level depends on absorption in the gut, reabsorption and excretion by the kidney, and the flux between the extracellular and skeletal pools. Phosphate homeostasis is a coordinated, complex system of crosstalk between the bone, intestine, kidney, and parathyroid gland. Dysfunction of this system has serious clinical consequences in healthy individuals and those with conditions, such as CKD, in which hyperphosphatemia is associated with increased risks of cardiovascular morbidity and mortality. The last half-century of renal research has helped define the contribution of the parathyroid hormone, calcitriol, fibroblast growth factor 23, and Klotho in the regulation of phosphate. However, despite new discoveries and insights gained during this time, what remains unchanged is the recognition that phosphate retention is the initiating factor for the development of many of the complications observed in CKD, namely secondary hyperparathyroidism and bone and cardiovascular diseases. Controlling phosphate load remains the primary goal in the treatment of CKD. This review discusses the clinical effects of dysregulated phosphate metabolism, particularly in CKD, and its association with cardiovascular disease. The importance of early control of phosphate load in the treatment of CKD is emphasized, and the latest research in the treatment of phosphate retention is discussed.
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Affiliation(s)
- Cynthia S Ritter
- Renal Division, Washington University School of Medicine, St. Louis, Missouri
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142
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Li J, Yuan J, Miao Z, Song Z, Yang Y, Tian W, Guo Y. Effect of Dietary Nutrient Density on Small Intestinal Phosphate Transport and Bone Mineralization of Broilers during the Growing Period. PLoS One 2016; 11:e0153859. [PMID: 27100791 PMCID: PMC4839609 DOI: 10.1371/journal.pone.0153859] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 04/05/2016] [Indexed: 01/19/2023] Open
Abstract
A 2 × 4 factorial experiment was conducted to determine the effects of dietary nutrient density on growth performance, small intestinal epithelial phosphate transporter expression, and bone mineralization of broiler chicks fed with diets with different nutrient densities and nonphytate phosphorus (NPP) levels. The broilers were fed with the same starter diets from 0 to 21 days of age. In the grower phase (day 22 to 42), the broilers were randomly divided into eight groups according to body weight. Relatively high dietary nutrient density (HDND) and low dietary nutrient density (LDND) diets were assigned metabolic energy (ME) values of 3,150 and 2,950 kcal/kg, respectively. Crude protein and essential amino acid levels were maintained in the same proportion as ME to prepare the two diet types. NPP levels were 0.25%, 0.30%, 0.35%, and 0.40% of the diets. Results showed that a HDND diet significantly increased the body weight gain (BWG) of broilers and significantly decreased the feed conversion ratio and NPP consumed per BWG. HDND significantly decreased tibial P content of the broilers. Conversely, mRNA expression of NaPi-IIb and protein expression of calbindin were significantly increased in the intestine of broilers fed a HDND diet. HDND also increased vitamin D receptor (VDR) expression, especially at a relatively low dietary NPP level (0.25%). The mRNA expression of NaPi-IIa in the kidneys was significantly increased at a relatively low dietary NPP level (0.25%) to maintain P balance. Tibial P, calcium, and ash content were significantly decreased, as were calbindin and VDR expression levels in the intestine at a low NPP level. Therefore, HDND improved the growth rate of broilers and increased the expression of phosphate and calcium transporter in the small intestine, but adversely affected bone mineralization.
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Affiliation(s)
- Jianhui Li
- College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Shanxi 030801, China
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Jianmin Yuan
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Zhiqiang Miao
- College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Shanxi 030801, China
| | - Zhigang Song
- Department of Animal Science, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Yu Yang
- College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Shanxi 030801, China
| | - Wenxia Tian
- College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Shanxi 030801, China
| | - Yuming Guo
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
- * E-mail:
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143
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The effects and mechanisms of SLC34A2 on tumorigenicity in human non-small cell lung cancer stem cells. Tumour Biol 2016; 37:10383-92. [PMID: 26846105 DOI: 10.1007/s13277-016-4928-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 01/28/2016] [Indexed: 01/06/2023] Open
Abstract
A novel paradigm in tumor biology suggests that non-small cell lung cancer (NSCLC) growth is driven by lung cancer stem cell-like cells (LCSCs), but molecular mechanisms regulating tumorigenic and self-renewal potential of LCSCs are still unclear. Here, we aim to investigate biological function of SLC34A2 in regulating tumorigenicity of LCSCs and its underlying mechanisms. Our findings testified that CD166(+) cells which were derived from fresh primary NSCLC samples displayed stem cell-like features. Fluorescence-activated cell sorting (FACS) analysis showed the presence of a variable fraction of CD166 cells in 15 out of 15 NSCLC samples. Significantly, CD166(+) LCSCs from primary NSCLC tumors expressed high level of SLC34A2 which was required for CD166(+) LCSCs tumorigenic and self-renewal potential. In NSCLC patient cohort, increased SLC34A2 expression correlated with histology, which suggests a potential role of SLC34A2 in CD166(+) LCSCs. Furthermore, Wnt/β-catenin pathway and Bmi1 were found necessary for tumorigenicity and self-renewal capacity of CD166(+) LCSCs by a series in vitro and in vivo experiments. Then, our study indicated that SLC34A2 regulated Bmi1 to promote tumorigenic and self-renewal potential of CD166(+) LCSCs through Wnt/β-catenin pathway. In this study, the characterization of molecular basis of SLC34A2 in CD166(+) LCSCs not only allows for better understanding of the mechanisms regulating tumorigenicity of this specific population of NSCLC cells but also provides insight into the gradual improvement of more effective cancer therapies against this disease.
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144
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El Borolossy R, El Wakeel LM, El Hakim I, Sabri N. Efficacy and safety of nicotinamide in the management of hyperphosphatemia in pediatric patients on regular hemodialysis. Pediatr Nephrol 2016; 31:289-96. [PMID: 26420678 DOI: 10.1007/s00467-015-3208-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 08/27/2015] [Accepted: 09/01/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Hyperphosphatemia is a common problem in patients with end-stage renal disease (ESRD) who are on maintenance hemodialysis (HD) and contributes to the development of secondary hyperparathyroidism and cardiovascular complications. Nicotinamide (NAM) has been shown in some studies to inhibit intestinal and renal sodium/phosphorus co-transporters and reduce serum phosphorus levels. We have therefore evaluated the efficacy and safety of NAM as adjunctive therapy to calcium-based phosphate binders to control hyperphosphatemia in hemodialysis patients. METHODS Sixty pediatric HD outpatients were randomly divided into two equally sized groups (30 children each). One group received calcium-based phosphate binder (control group), and the other received both the calcium-based phosphate binder + NAM at a dose of 100 mg twice or three times daily (nicotinamide group). Both groups were followed for a 6-month period. RESULTS Over the 6-month treatment period, children in the NAM group showed a significant decline in the levels of serum phosphorus (p = 0.0001), serum calcium-phosphorus (Ca × P; p = 0.0001) product and parathyroid hormone (p = 0.02) versus baseline values and those of the control group. After 6 months of NAM treatment, the mean serum high-density lipoprotein cholesterol levels had increased significantly (p = 0.01), and the median serum triglyceride levels had decreased (p = 0.009). There was no significant change in any of these parameters among the children of the control group. The major adverse events associated with the NAM therapy were diarrhea, flushing and nausea. CONCLUSION The addition of NAM to therapy with phosphate binders is effective in lowering phosphorus levels and has a beneficial effect on the lipid profile with only mild side effects.
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Affiliation(s)
- Radwa El Borolossy
- Department of Clinical Pharmacy, Faculty of Pharmacy, Ain Shams University, 4 Street 292, New Maadi, Cairo, Egypt
| | - Lamia Mohamed El Wakeel
- Department of Clinical Pharmacy, Faculty of Pharmacy, Ain Shams University, 4 Street 292, New Maadi, Cairo, Egypt.
| | - Ihab El Hakim
- Department of Pediatrics, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Nagwa Sabri
- Department of Clinical Pharmacy, Faculty of Pharmacy, Ain Shams University, 4 Street 292, New Maadi, Cairo, Egypt
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145
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Ohata Y, Ozono K, Michigami T. Current concepts in perinatal mineral metabolism. Clin Pediatr Endocrinol 2016; 25:9-17. [PMID: 26865750 PMCID: PMC4738188 DOI: 10.1297/cpe.25.9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/26/2015] [Indexed: 12/03/2022] Open
Abstract
The serum levels of calcium (Ca) and phosphate are maintained higher in the fetus than in
the pregnant mother, especially in late gestation, to meet the demands of fetal bone
development. In order to maintain this fetal stage-specific mineral homeostasis, the
placenta plays a critical role through active transcellular mineral transport. Although
the molecular mechanism of transplacental Ca transport has been well studied, little is
known about the transport mechanism of phosphate and magnesium. Maternal mineral
homeostasis is also altered during pregnancy to supply minerals to the fetus. In the
lactating mother, osteocytic osteolysis is suggested to be involved in the supply of
minerals to the baby. The levels of some calcitropic and phosphotropic (Ca- and
phosphate-regulating, respectively) hormones in the fetus are also different from those in
the adult. The PTH level in the fetus is lower than that in the mother and nonpregnant
adult. It is suggested, however, that low fetal PTH plays an important role in fetal
mineral metabolism. The concentration of PTHrP in the fetus is much higher than that of
PTH and plays a critical role in perinatal Ca homeostasis. Uncovering the molecular
mechanisms for fetal stage-specific mineral metabolism will lead to better management of
perinatal patients with mineral abnormalities.
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Affiliation(s)
- Yasuhisa Ohata
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan; Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Toshimi Michigami
- Department of Bone and Mineral Research, Osaka Medical Center and Research Institute for Maternal and Child Health, Izumi, Japan
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146
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Tatsumi S, Miyagawa A, Kaneko I, Shiozaki Y, Segawa H, Miyamoto KI. Regulation of renal phosphate handling: inter-organ communication in health and disease. J Bone Miner Metab 2016; 34:1-10. [PMID: 26296817 DOI: 10.1007/s00774-015-0705-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 07/16/2015] [Indexed: 01/18/2023]
Abstract
In this review, we focus on the interconnection of inorganic phosphate (Pi) homeostasis in the network of the bone-kidney, parathyroid-kidney, intestine-kidney, and liver-kidney axes. Such a network of organ communication is important for body Pi homeostasis. Normalization of serum Pi levels is a clinical target in patients with chronic kidney disease (CKD). Particularly, disorders of the fibroblast growth factor 23/klotho system are observed in early CKD. Identification of phosphaturic factors from the intestine and liver may enhance our understanding of body Pi homeostasis and Pi metabolism disturbances in CKD patients.
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Affiliation(s)
- Sawako Tatsumi
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Atsumi Miyagawa
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Ichiro Kaneko
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Yuji Shiozaki
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Hiroko Segawa
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan
| | - Ken-Ichi Miyamoto
- Department of Molecular Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503, Japan.
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147
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Pulskens WP, Verkaik M, Sheedfar F, van Loon EP, van de Sluis B, Vervloet MG, Hoenderop JG, Bindels RJ. Deregulated Renal Calcium and Phosphate Transport during Experimental Kidney Failure. PLoS One 2015; 10:e0142510. [PMID: 26566277 PMCID: PMC4643984 DOI: 10.1371/journal.pone.0142510] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 10/22/2015] [Indexed: 12/17/2022] Open
Abstract
Impaired mineral homeostasis and inflammation are hallmarks of chronic kidney disease (CKD), yet the underlying mechanisms of electrolyte regulation during CKD are still unclear. Here, we applied two different murine models, partial nephrectomy and adenine-enriched dietary intervention, to induce kidney failure and to investigate the subsequent impact on systemic and local renal factors involved in Ca(2+) and Pi regulation. Our results demonstrated that both experimental models induce features of CKD, as reflected by uremia, and elevated renal neutrophil gelatinase-associated lipocalin (NGAL) expression. In our model kidney failure was associated with polyuria, hypercalcemia and elevated urinary Ca(2+) excretion. In accordance, CKD augmented systemic PTH and affected the FGF23-αklotho-vitamin-D axis by elevating circulatory FGF23 levels and reducing renal αklotho expression. Interestingly, renal FGF23 expression was also induced by inflammatory stimuli directly. Renal expression of Cyp27b1, but not Cyp24a1, and blood levels of 1,25-dihydroxy vitamin D3 were significantly elevated in both models. Furthermore, kidney failure was characterized by enhanced renal expression of the transient receptor potential cation channel subfamily V member 5 (TRPV5), calbindin-D28k, and sodium-dependent Pi transporter type 2b (NaPi2b), whereas the renal expression of sodium-dependent Pi transporter type 2a (NaPi2a) and type 3 (PIT2) were reduced. Together, our data indicates two different models of experimental kidney failure comparably associate with disturbed FGF23-αklotho-vitamin-D signalling and a deregulated electrolyte homeostasis. Moreover, this study identifies local tubular, possibly inflammation- or PTH- and/or FGF23-associated, adaptive mechanisms, impacting on Ca(2+)/Pi homeostasis, hence enabling new opportunities to target electrolyte disturbances that emerge as a consequence of CKD development.
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Affiliation(s)
- Wilco P. Pulskens
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
- Dept. of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Melissa Verkaik
- Dept. of Nephrology, VU University Medical Center, Amsterdam, The Netherlands
| | - Fareeba Sheedfar
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ellen P. van Loon
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bart van de Sluis
- Dept. of Pediatrics, Molecular Genetics Section, University Medical Center Groningen, Groningen, The Netherlands
| | - Mark G. Vervloet
- Dept. of Nephrology, VU University Medical Center, Amsterdam, The Netherlands
| | - Joost G. Hoenderop
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J. Bindels
- Dept. of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands
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148
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Villa-Bellosta R. Vascular Calcification Revisited: A New Perspective for Phosphate Transport. Curr Cardiol Rev 2015; 11:341-351. [PMID: 26242187 PMCID: PMC4774640 DOI: 10.2174/1573403x11666150805120505] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 03/10/2015] [Accepted: 03/11/2015] [Indexed: 12/30/2022] Open
Abstract
Elevated serum phosphorus has emerged as a key risk factor for pathologic calcification of
cardiovascular structures, or vascular calcification (VC). To prevent the formation of calciumphosphate
deposits (CPD), the body uses adenosine-5’-triphosphate (ATP) to synthesize inhibitors of
calcification, including proteins and inhibitors of low molecular weight. Extracellular pyrophosphate
(PPi) is a potent inhibitor of VC, which is produced during extracellular hydrolysis of ATP. Loss of
function in the enzymes and transporters that are involved in the cycle of extracellular ATP, including
Pi transporters, leads to excessive deposition of calcium-phosphate salts. Treatment of hyperphosphatemia
with Pi-binders and Injection of exogenous PPi are the effective treatments to prevent CPD
in the aortic wall. The role of sodium phosphate cotransporters in ectopic calcification is contradictory and not well defined,
but their important role in the control of intracellular Pi levels and the synthesis of ATP make them an important
target to study.
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149
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Ge G, Zhou C, Ren Y, Tang X, Wang K, Zhang W, Niu L, Zhou Y, Yan Y, He J. Enhanced SLC34A2 in breast cancer stem cell-like cells induces chemotherapeutic resistance to doxorubicin via SLC34A2-Bmi1-ABCC5 signaling. Tumour Biol 2015; 37:5049-62. [PMID: 26546432 DOI: 10.1007/s13277-015-4226-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/12/2015] [Indexed: 12/23/2022] Open
Abstract
Even though early detection methods and treatment options are greatly improved, chemoresistance is still a tremendous challenge for breast cancer therapy. Breast cancer stem cells (BCSCs) represent a subpopulation that is central to chemoresistance. We aim to investigate the relationship between SLC34A2 and chemoresistance in BCSCs and identify the underlying mechanisms by which SLC34A2 regulates chemoresistance in BCSCs. Fluorescence Activated Cell Sorting (FACS) analysis showed the presence of a variable fraction of CD44(+)CD24(-) cells in 25 out of 25 breast cancer samples. We cultured primary breast cancer sample cells and breast cancer cell line cells to induce sphere formation in serum-free medium. Following sorting of CD44(+)CD24(-) cells from spheres, we showed that CD44(+)CD24(-) cells displayed stem cell-like features and were resistant to chemotherapy drug doxorubicin. Significantly, enhanced SLC34A2 expression correlated with chemoresponse and survival of breast cancer patients. We subsequently indicated that increased SLC34A2 expression in BCSCs directly contributed to their chemoresistance by a series of in vitro and in vivo experiments. Furthermore, we demonstrated that SLC34A2 induced chemoresistance in BCSCs via SLC34A2-Bmi1-ABCC5 signaling. Finally, we showed that ABCC5 was a direct transcriptional target of Bmi1 by chromatin immunoprecipitation (ChIP). In conclusion, our work indicated that decreased SLC34A2 expression sensitized BCSCs to doxorubicin via SLC34A2-Bmi1-ABCC5 signaling and shed new light on understanding the mechanism of chemoresistance in BCSCs. This study not only bridges the missing link between stem cell-related transcription factor (Bmi1) and ABC transporter (ABCC5) but also contributes to development of potential therapeutics against breast cancer.
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Affiliation(s)
- Guanqun Ge
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China
| | - Can Zhou
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China
| | - Yu Ren
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China
| | - Xiaojiang Tang
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China
| | - Ke Wang
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China
| | - Wei Zhang
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China
| | - Ligang Niu
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China
| | - Yuhui Zhou
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China
| | - Yu Yan
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China
| | - Jianjun He
- Department of Breast Surgery, the First Affiliated Hospital of Xi'an Jiaotong University, NO. 277, Yantaxi Road, Xi'an, 710061, Shanxi Province, People's Republic of China.
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Hernando N, Myakala K, Simona F, Knöpfel T, Thomas L, Murer H, Wagner CA, Biber J. Intestinal Depletion of NaPi-IIb/Slc34a2 in Mice: Renal and Hormonal Adaptation. J Bone Miner Res 2015; 30:1925-37. [PMID: 25827490 DOI: 10.1002/jbmr.2523] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 03/26/2015] [Accepted: 03/27/2015] [Indexed: 11/10/2022]
Abstract
The Na(+) -dependent phosphate-cotransporter NaPi-IIb (SLC34A2) is widely expressed, with intestine, lung, and testis among the organs with highest levels of mRNA abundance. In mice, the intestinal expression of NaPi-IIb is restricted to the ileum, where the cotransporter localizes specifically at the brush border membrane (BBM) and mediates the active transport of inorganic phosphate (Pi). Constitutive full ablation of NaPi-IIb is embryonically lethal whereas the global but inducible removal of the transporter in young mice leads to intestinal loss of Pi and lung calcifications. Here we report the generation of a constitutive but intestinal-specific NaPi-IIb/Slc34a2-deficient mouse model. Constitutive intestinal ablation of NaPi-IIb results in viable pups with normal growth. Homozygous mice are characterized by fecal wasting of Pi and complete absence of Na/Pi cotransport activity in BBM vesicles (BBMVs) isolated from ileum. In contrast, the urinary excretion of Pi is reduced in these animals. The plasma levels of Pi are similar in wild-type and NaPi-IIb-deficient mice. In females, the reduced phosphaturia associates with higher expression of NaPi-IIa and higher Na/Pi cotransport activity in renal BBMVs, as well as with reduced plasma levels of intact FGF-23. A similar trend is found in males. Thus, NaPi-IIb is the only luminal Na(+) -dependent Pi transporter in the murine ileum and its absence is fully compensated for in adult females by a mechanism involving the bone-kidney axis. The contribution of this mechanism to the adaptive response is less apparent in adult males.
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Affiliation(s)
- Nati Hernando
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP). University of Zurich, Zurich, Switzerland
| | - Komuraiah Myakala
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP). University of Zurich, Zurich, Switzerland
| | - Fabia Simona
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP). University of Zurich, Zurich, Switzerland
| | - Thomas Knöpfel
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP). University of Zurich, Zurich, Switzerland
| | - Linto Thomas
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP). University of Zurich, Zurich, Switzerland
| | - Heini Murer
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP). University of Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP). University of Zurich, Zurich, Switzerland
| | - Jürg Biber
- Institute of Physiology and Zurich Center for Integrative Human Physiology (ZIHP). University of Zurich, Zurich, Switzerland
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