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Towler DA. Parathyroid hormone-PTH1R signaling in cardiovascular disease and homeostasis. Trends Endocrinol Metab 2024; 35:648-660. [PMID: 38429163 PMCID: PMC11233248 DOI: 10.1016/j.tem.2024.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Revised: 02/03/2024] [Accepted: 02/05/2024] [Indexed: 03/03/2024]
Abstract
Primary hyperparathyroidism (pHPT) afflicts our aging population with an incidence approaching 50 per 100 000 patient-years at a female:male ratio of ~3:1. Decisions surrounding surgical management are currently driven by age, hypercalcemia severity, presence of osteoporosis, renal insufficiency, or hypercalciuria with or without nephrolithiasis. Cardiovascular (CV) disease (CVD) is not systematically considered. This is notable since the parathyroid hormone (PTH) 1 receptor (PTH1R) is biologically active in the vasculature, and adjusted CV mortality risk is increased almost threefold in individuals with pHPT who do not meet contemporary recommendations for surgical cure. We provide an overview of epidemiology, pharmacology, and physiology that highlights the need to: (i) identify biomarkers that establish a healthy 'set point' for CV PTH1R signaling tone; (ii) better understand the pharmacokinetic-pharmacodynamic (PK-PD) relationships of PTH1R ligands in CV homeostasis; and (iii) incorporate CVD risk assessment into the management of hyperparathyroidism.
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Affiliation(s)
- Dwight A Towler
- Department of Internal Medicine - Endocrine Division, Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, UT Southwestern Medical Center, Dallas, TX 75390, USA.
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2
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Koike M, Sato T, Shiozaki Y, Komiya A, Miura M, Higashi A, Ishikawa A, Takayanagi K, Uga M, Miyamoto KI, Segawa H. Involvement of α-klotho in growth hormone (GH) signaling. J Clin Biochem Nutr 2024; 74:221-229. [PMID: 38799134 PMCID: PMC11111466 DOI: 10.3164/jcbn.23-127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 01/10/2024] [Indexed: 05/29/2024] Open
Abstract
Growth hormone (GH) exerts multiple effects on different organs directly or via its main mediator, insulin-like growth factor1 (IGF1). In this study, we focused on the novel relationship between GH action and the antiaging hormone α-klotho. Immunofluorescent staining of α-klotho was observed in the renal distal tubules and pituitary glands of somatostatin- and GH-positive cells in wild-type (WT) mice. Treatment of 4-week-old WT mice with GH increased IGF1 mRNA expression in the pituitary gland, liver, heart, kidney, and bone but increased α-klotho mRNA expression only in the pituitary gland, kidney, and bone. Increased α-klotho protein levels were observed in the kidney but not in the pituitary gland. No induction of α-klotho RNA expression by GH was observed in juvenile mice with kidney disease, indicating GH resistance. Furthermore, GH and α-klotho supplementation in HEK293 cells transfected with GHR increased Janus kinase 2 mRNA (a GH downstream signal) expression compared to supplementation with GH alone. In conclusion, we suggest that 1) the kidney is the main source of secreted α-klotho, which is detected in blood by the downstream action of GH, 2) α-klotho induction by GH is resistant in kidney disease, and 3) α-klotho might be an enhanced regulator of GH signaling.
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Affiliation(s)
- Megumi Koike
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Tetsuhiko Sato
- General Medicine, Nagoya Daini Red Cross Hospital, 2-9 Myoken-cho, Showa-ku, Nagoya 466-8650, Japan
| | - Yuji Shiozaki
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Aoi Komiya
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Mizuki Miura
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Ayami Higashi
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Akane Ishikawa
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Kaori Takayanagi
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Minori Uga
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
| | - Ken-ichi Miyamoto
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
- Graduate School of Agriculture, Ryukoku University, 1-5 Yokotani, Seta Oe-cho, Otsu, Shiga 520-2194, Japan
| | - Hiroko Segawa
- Department of Applied Nutrition, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima 770-8503, Japan
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Yoon SH, Meyer MB, Arevalo C, Tekguc M, Zhang C, Wang JS, Castro Andrade CD, Strauss K, Sato T, Benkusky NA, Lee SM, Berdeaux R, Foretz M, Sundberg TB, Xavier RJ, Adelmann CH, Brooks DJ, Anselmo A, Sadreyev RI, Rosales IA, Fisher DE, Gupta N, Morizane R, Greka A, Pike JW, Mannstadt M, Wein MN. A parathyroid hormone/salt-inducible kinase signaling axis controls renal vitamin D activation and organismal calcium homeostasis. J Clin Invest 2023; 133:e163627. [PMID: 36862513 PMCID: PMC10145948 DOI: 10.1172/jci163627] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 02/23/2023] [Indexed: 03/03/2023] Open
Abstract
The renal actions of parathyroid hormone (PTH) promote 1,25-vitamin D generation; however, the signaling mechanisms that control PTH-dependent vitamin D activation remain unknown. Here, we demonstrated that salt-inducible kinases (SIKs) orchestrated renal 1,25-vitamin D production downstream of PTH signaling. PTH inhibited SIK cellular activity by cAMP-dependent PKA phosphorylation. Whole-tissue and single-cell transcriptomics demonstrated that both PTH and pharmacologic SIK inhibitors regulated a vitamin D gene module in the proximal tubule. SIK inhibitors increased 1,25-vitamin D production and renal Cyp27b1 mRNA expression in mice and in human embryonic stem cell-derived kidney organoids. Global- and kidney-specific Sik2/Sik3 mutant mice showed Cyp27b1 upregulation, elevated serum 1,25-vitamin D, and PTH-independent hypercalcemia. The SIK substrate CRTC2 showed PTH and SIK inhibitor-inducible binding to key Cyp27b1 regulatory enhancers in the kidney, which were also required for SIK inhibitors to increase Cyp27b1 in vivo. Finally, in a podocyte injury model of chronic kidney disease-mineral bone disorder (CKD-MBD), SIK inhibitor treatment stimulated renal Cyp27b1 expression and 1,25-vitamin D production. Together, these results demonstrated a PTH/SIK/CRTC signaling axis in the kidney that controls Cyp27b1 expression and 1,25-vitamin D synthesis. These findings indicate that SIK inhibitors might be helpful for stimulation of 1,25-vitamin D production in CKD-MBD.
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Affiliation(s)
- Sung-Hee Yoon
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Mark B. Meyer
- Department of Nutritional Sciences, University of Wisconsin — Madison, Madison, Wisconsin, USA
| | - Carlos Arevalo
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Murat Tekguc
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Chengcheng Zhang
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Jialiang S. Wang
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Katelyn Strauss
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Tadatoshi Sato
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Nancy A. Benkusky
- Department of Nutritional Sciences, University of Wisconsin — Madison, Madison, Wisconsin, USA
| | - Seong Min Lee
- Department of Nutritional Sciences, University of Wisconsin — Madison, Madison, Wisconsin, USA
| | - Rebecca Berdeaux
- Department of Integrative Biology and Pharmacology, McGovern Medical School at The University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Marc Foretz
- Université Paris Cité, Institut Cochin, CNRS, INSERM, Paris, France
| | | | - Ramnik J. Xavier
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
- Center for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | | | - Daniel J. Brooks
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Ruslan I. Sadreyev
- Department of Molecular Biology, and
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Ivy A. Rosales
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - David E. Fisher
- Cutaneous Biology Research Center, Department of Dermatology
| | - Navin Gupta
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Ryuji Morizane
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| | - Anna Greka
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - J. Wesley Pike
- Department of Biochemistry, University of Wisconsin — Madison, Madison, Wisconsin, USA
| | - Michael Mannstadt
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Marc N. Wein
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
- Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
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Takenaka T, Hasan A, Marumo T, Inoue T, Miyazaki T, Suzuki H, Kurosaki Y, Ishii N, Nishiyama A, Hayashi M. Klotho Supplementation Reverses Renal Dysfunction and Interstitial Fibrosis in Remnant Kidney. Kidney Blood Press Res 2023; 48:326-337. [PMID: 37019097 DOI: 10.1159/000530469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 03/10/2023] [Indexed: 04/07/2023] Open
Abstract
INTRODUCTION While recent investigations show that klotho exerts renoprotective actions, it has not been fully addressed whether klotho protein supplementation reverses renal damage. METHODS The impacts of subcutaneous klotho supplementation on rats with subtotal nephrectomy were examined. Animals were divided into 3 groups: group 1 (short remnant [SR]): remnant kidney for 4 weeks, group 2 (long remnant [LR]): remnant kidney for 12 weeks, and group 3 (klotho supplementation [KL]): klotho protein (20 μg/kg/day) supplementation on the remnant kidney. Blood pressure, blood and urine compositions with conventional methods such as enzyme-linked immunosorbent assay and radioimmunoassay, kidney histology, and renal expressions of various genes were analyzed. In vitro studies were also performed to support in vivo findings. RESULTS Klotho protein supplementation decreased albuminuria (-43%), systolic blood pressure (-16%), fibroblast growth factor (FGF) 23 (-51%) and serum phosphate levels (-19%), renal angiotensin II concentration (-43%), fibrosis index (-70%), renal expressions of collagen I (-55%), and transforming growth factor β (-59%) (p < 0.05 for all). Klotho supplementation enhanced fractional excretion of phosphate (+45%), glomerular filtration rate (+76%), renal expressions of klotho (+148%), superoxide dismutase (+124%), and bone morphogenetic protein (BMP) 7 (+174%) (p < 0.05 for all). CONCLUSION Our data indicated that klotho protein supplementation inactivated renal renin-angiotensin system, reducing blood pressure and albuminuria in remnant kidney. Furthermore, exogenous klotho protein supplementation elevated endogenous klotho expression to increase phosphate excretion with resultant reductions in FGF23 and serum phosphate. Finally, klotho supplementation reversed renal dysfunction and fibrosis in association with improved BMP7 in remnant kidney.
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Affiliation(s)
- Tsuneo Takenaka
- Department of Nephrology, International University of Health and Welfare, Tokyo, Japan
| | - Arif Hasan
- Department of Nephrology, International University of Health and Welfare, Tokyo, Japan
| | - Takeshi Marumo
- Department of Nephrology, International University of Health and Welfare, Tokyo, Japan
| | - Tsutomu Inoue
- Department of Nephrology, Saitama Medical University, Iruma, Japan
| | - Takashi Miyazaki
- Department of Nephrology, Saitama Medical University, Iruma, Japan
| | - Hiromichi Suzuki
- Department of Nephrology, Saitama Medical University, Iruma, Japan
| | | | - Naohito Ishii
- Department of Biochemistry, Kitasato University, Sagamihara, Japan
| | - Akira Nishiyama
- Department of Pharmacology, Kagawa University, Takamatsu, Japan
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Young K, Beggs MR, Grimbly C, Alexander RT. Regulation of 1 and 24 hydroxylation of vitamin D metabolites in the proximal tubule. Exp Biol Med (Maywood) 2022; 247:1103-1111. [PMID: 35482362 PMCID: PMC9335508 DOI: 10.1177/15353702221091982] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Calcium and phosphate are critical for numerous physiological processes. Consequently, the plasma concentration of these ions are tightly regulated. Calcitriol, the active form of vitamin D, is a positive modulator of mineralization as well as calcium and phosphate metabolism. The molecular and physiological effects of calcitriol are well documented. Calcitriol increases blood calcium and phosphate levels by increasing absorption from the intestine, and resorption of bone. Calcitriol synthesis is a multistep process. A precursor is first made via skin exposure to UV, it is then 25-hydroxylated in the liver to form 25-hydroxyitamin D. The next hydroxylation step occurs in the renal proximal tubule via the 1-αhydroxylase enzyme (encoded by CYP27B1) thereby generating 1,25-dihydroxyvitamin D, that is, calcitriol. At the same site, the 25-hydroxyvitamin D 24-hydroxlase enzyme encoded by CYP24A1 can hydroxylate 25-hydroxyvitamin D or calcitriol to deactivate the hormone. Plasma calcitriol levels are primarily determined by the regulated expression of CYP27B1 and CYP24A1. This occurs in response to parathyroid hormone (increases CYP27B1), calcitriol itself (decreases CYP27B1 and increases CYP24A1), calcitonin (increases or decreases CYP24A1 and increases CYP27B1), FGF23 (decreases CYP27B1 and increases CYP24A1) and potentially plasma calcium and phosphate levels themselves (mixed effects). Herein, we review the regulation of CYP27B1 and CYP24A1 transcription in response to the action of classic phophocalciotropic hormones and explore the possibility of direct regulation by plasma calcium.
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Affiliation(s)
- Kennedi Young
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada,Women and Children’s Health Institute, Edmonton, AB T6G 1C9, Canada
| | - Megan R Beggs
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada,Women and Children’s Health Institute, Edmonton, AB T6G 1C9, Canada
| | - Chelsey Grimbly
- Department of Paediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada
| | - R Todd Alexander
- Department of Physiology, University of Alberta, Edmonton, AB T6G 2H7, Canada,Women and Children’s Health Institute, Edmonton, AB T6G 1C9, Canada,Department of Paediatrics, University of Alberta, Edmonton, AB T6G 1C9, Canada,R Todd Alexander.
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6
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Bover J, Arana C, Ureña P, Torres A, Martín-Malo A, Fayos L, Coll V, Lloret MJ, Ochoa J, Almadén Y, Guirado L, Rodríguez M. Hyporesponsiveness or resistance to the action of parathyroid hormone in chronic kidney disease. Nefrologia 2021; 41:514-528. [PMID: 36165134 DOI: 10.1016/j.nefroe.2021.11.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 12/20/2020] [Indexed: 06/16/2023] Open
Abstract
Secondary hyperparathyroidism (SHPT) is an integral component of the chronic kidney disease-mineral and bone disorder (CKD-MBD). Many factors have been associated with the development and progression of SHPT but the presence of skeletal or calcemic resistance to the action of PTH in CKD has often gone unnoticed. The term hyporesponsiveness to PTH is currently preferred and, in this chapter, we will not only review the scientific timeline but also some of the molecular mechanisms behind. Moreover, the presence of resistance to the biological action of PTH is not unique in CKD since resistance to other hormones has also been described ("uremia as a receptor disease"). This hyporesponsiveness carries out important clinical implications since it explains, at least partially, not only the progressive nature of the pathogenesis of CKD-related PTH hypersecretion and parathyroid hyperplasia but also the increasing prevalence of adynamic bone disease in the CKD population. Therefore, we underline the importance of PTH control in all CKD stages, but not aiming to completely normalize PTH levels since a certain degree of SHPT may represent an adaptive clinical response. Future studies at the molecular level, i.e. on uremia or the recent description of the calcium-sensing receptor as a phosphate sensor, may become of great value beyond their significance to explain just the hyporesponsiveness to PTH in CKD.
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Affiliation(s)
- Jordi Bover
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, Spain.
| | - Carolt Arana
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, Spain
| | - Pablo Ureña
- AURA Nord Saint Ouen y Departamento de Fisiología Renal, Hospital Necker, Universidad de París Descartes, Paris, France
| | - Armando Torres
- Servicio de Nefrología, Hospital Universitario de Canarias, REDinREN, Universidad de La Laguna, Tenerife, Spain
| | - Alejandro Martín-Malo
- Unidad de Gestión Clinica Nefrología, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofía, Universidad de Córdoba, Córdoba, Spain; Red Nacional de Investigación en Nefrología (REDinREN), Instituto de Salud Carlos III, Madrid, Spain
| | - Leonor Fayos
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, Spain
| | - Verónica Coll
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, Spain
| | - María Jesús Lloret
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, Spain
| | - Jackson Ochoa
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, Spain
| | - Yolanda Almadén
- Unidad de Gestión Clínica Medicina Interna, Lipid and Atherosclerosis Unit, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofía, Universidad de Córdoba, Córdoba, Spain; CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
| | - Lluis Guirado
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, Spain
| | - Mariano Rodríguez
- Unidad de Gestión Clinica Nefrología, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofía, Universidad de Córdoba, Córdoba, Spain; Red Nacional de Investigación en Nefrología (REDinREN), Instituto de Salud Carlos III, Madrid, Spain
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Bover J, Arana C, Ureña P, Torres A, Martín-Malo A, Fayos L, Coll V, Lloret MJ, Ochoa J, Almadén Y, Guirado L, Rodríguez M. Hyporesponsiveness or resistance to the action of parathyroid hormone in chronic kidney disease. Nefrologia 2021. [PMID: 33985858 DOI: 10.1016/j.nefro.2020.12.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Secondary hyperparathyroidism (SHPT) is an integral component of the chronic kidney disease-mineral and bone disorder (CKD-MBD). Many factors have been associated with the development and progression of SHPT but the presence of skeletal or calcemic resistance to the action of PTH in CKD has often gone unnoticed. The term hyporesponsiveness to PTH is currently preferred and, in this chapter, we will not only review the scientific timeline but also some of the molecular mechanisms behind. Moreover, the presence of resistance to the biological action of PTH is not unique in CKD since resistance to other hormones has also been described ("uremia as a receptor disease"). This hyporesponsiveness carries out important clinical implications since it explains, at least partially, not only the progressive nature of the pathogenesis of CKD-related PTH hypersecretion and parathyroid hyperplasia but also the increasing prevalence of adynamic bone disease in the CKD population. Therefore, we underline the importance of PTH control in all CKD stages, but not aiming to completely normalize PTH levels since a certain degree of SHPT may represent an adaptive clinical response. Future studies at the molecular level, i.e. on uremia, or the recent description of the calcium-sensing receptor as a phosphate sensor, may become of great value beyond their significance to explain just the hyporesponsiveness to PTH in CKD.
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Affiliation(s)
- Jordi Bover
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, España.
| | - Carolt Arana
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, España
| | - Pablo Ureña
- AURA Nord Saint Ouen y Departamento de Fisiología Renal, Hospital Necker, Universidad de París Descartes, París, Francia
| | - Armando Torres
- Servicio de Nefrología, Hospital Universitario de Canarias, REDinREN, Universidad de La Laguna, Tenerife, España
| | - Alejandro Martín-Malo
- Unidad de Gestión Clínica Nefrología, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofía, Universidad de Córdoba, Córdoba, España; Red Nacional de Investigación en Nefrología (REDinREN), Instituto de Salud Carlos III, Madrid, España
| | - Leonor Fayos
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, España
| | - Verónica Coll
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, España
| | - María Jesús Lloret
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, España
| | - Jackson Ochoa
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, España
| | - Yolanda Almadén
- Unidad de Gestión Clínica Medicina Interna, Lipid and Atherosclerosis Unit, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofía, Universidad de Córdoba, Córdoba, España; CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, España
| | - Lluis Guirado
- Servicio de Nefrología, Fundació Puigvert, IIB Sant Pau, REDinREN, Barcelona, España
| | - Mariano Rodríguez
- Unidad de Gestión Clínica Nefrología, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Hospital Universitario Reina Sofía, Universidad de Córdoba, Córdoba, España; Red Nacional de Investigación en Nefrología (REDinREN), Instituto de Salud Carlos III, Madrid, España
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Klotho supplementation attenuates blood pressure and albuminuria in murine model of IgA nephropathy. J Hypertens 2021; 39:1567-1576. [PMID: 33758157 DOI: 10.1097/hjh.0000000000002845] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND Klotho interacts with various membrane proteins, such as transforming growth factor-β (TGFβ) and insulin-like growth factor (IGF) receptors. The renal expression of klotho is diminished in chronic kidney disease. METHOD In this study, we assessed the effects of klotho supplementation on a murine model of IgA nephropathy. Twenty-four-week-old hyper serum IgA (HIGA) mice were subcutaneously injected daily with recombinant human klotho protein (20 μg/kg per day) or the vehicle. After 2 months, the mice were killed using an anesthesia overdose and their kidneys were harvested for analysis. RESULTS Supplementation of exogenous klotho protein reduced SBP, albuminuria, 8-epi-prostaglandin F2α excretion, glomerular filtration rate, renal angiotensin II concentration, and angiotensinogen expression in HIGA mice. Additionally, it enhanced renal expression of superoxide dismutase (SOD) and renal klotho itself. The findings using laser-manipulated microdissection demonstrated that klotho supplementation reduced the glomerular expression of TGFβ, fibronectin, and IGF, and increased the glomerular expression of connexin (Cx) 40. CONCLUSION These results indicate that klotho supplementation reduces blood pressure by suppressing the renin--angiotensin system in HIGA mice. Klotho inhibits IGF signaling to preserve glomerular Cx40 levels, ameliorating albuminuria in HIGA mice. Klotho protein supplementation attenuates mesangial expansion by inhibiting TGFβ signaling in HIGA mice.
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Yi HJ, Lee JB, Lee KP, Oh YI, Song KH, Seo KW. Investigation on urinary and serum alpha klotho in dogs with chronic kidney disease. BMC Vet Res 2020; 16:246. [PMID: 32677951 PMCID: PMC7364505 DOI: 10.1186/s12917-020-02458-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/06/2020] [Indexed: 01/16/2023] Open
Abstract
Background As a co-receptor for fibroblast growth factor 23, klotho plays a pivotal role in phosphate metabolism. The kidney is known to be the main source of soluble alpha-klotho and the principal regulator of its concentration. Previous studies in human participants showed that the concentration of soluble alpha-klotho in serum and urine decreased in chronic kidney disease (CKD) patients. However, no previous study has assessed soluble alpha-klotho levels in dogs. This study aimed to measure serum and urinary alpha-klotho levels in CKD dogs and identify their associations with International Renal Interest Society (IRIS) CKD stages and other parameters known to be associated with CKD. Results Serum and urinary alpha klotho concentrations were measured by a commercially available canine-specific sandwich enzyme-linked immunosorbent assay kit and compared between groups by a nonparametric Kruskal–Wallis test. Spearman’s correlation coefficient was used to evaluate the relationships between variables. A stepwise multiple regression analysis was performed to estimate the effects of independent predictors on klotho concentrations. The urine klotho-to-creatinine ratio (UrKl/Cr) was significantly lower in stage 3 dogs than the control group and was significantly lower in dogs with stage 3 and 4 CKD than in those with stage 1 and 2 disease. UrKl/Cr was negatively correlated with serum symmetric dimethylarginine (sSDMA), blood urea nitrogen (BUN), creatinine, and phosphorus concentration. Serum alpha-klotho concentration in dogs with stages 2 and 3 CKD was significantly lower than those in the control group. There was no significant correlation between serum alpha-klotho and BUN, creatinine, and phosphorus concentrations. No statistically significant differences were observed in UrKl/Cr and serum alpha-klotho concentration between groups based on sex, age, urine protein-to-creatinine ratio (UPC), or blood pressure. Conclusions UrKl/Cr decreased in dogs with advanced CKD, and it was negatively correlated with sSDMA, BUN, creatinine, and phosphorus concentrations. Thus, klotho is associated with CKD and its clinical consequences, including CKD-mineral bone disorder, in dogs. Although serum klotho concentration was negatively correlated with sSDMA levels, it was not apparently related to IRIS CKD stage or other parameters known to be associated with CKD.
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Affiliation(s)
- Hong Jae Yi
- VMTH of College of Veterinary Medicine, Chungnam National University, N13-2, #308, 99 Daehak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Jong Bok Lee
- College of Veterinary Medicine, Kangwon National University, Chuncheon, Korea
| | - Kyu Pil Lee
- VMTH of College of Veterinary Medicine, Chungnam National University, N13-2, #308, 99 Daehak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Ye-In Oh
- VMTH of College of Veterinary Medicine, Chungnam National University, N13-2, #308, 99 Daehak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Kun Ho Song
- VMTH of College of Veterinary Medicine, Chungnam National University, N13-2, #308, 99 Daehak-ro, Yuseong-gu, Daejeon, Republic of Korea
| | - Kyoung Won Seo
- VMTH of College of Veterinary Medicine, Chungnam National University, N13-2, #308, 99 Daehak-ro, Yuseong-gu, Daejeon, Republic of Korea.
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10
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Dhayat NA, Pruijm M, Ponte B, Ackermann D, Leichtle AB, Devuyst O, Ehret G, Guessous I, Pechère-Bertschi A, Pastor J, Martin PY, Burnier M, Fiedler GM, Vogt B, Moe OW, Bochud M, Fuster DG. Parathyroid Hormone and Plasma Phosphate Are Predictors of Soluble α-Klotho Levels in Adults of European Descent. J Clin Endocrinol Metab 2020; 105:5644279. [PMID: 31774122 PMCID: PMC7341480 DOI: 10.1210/clinem/dgz232] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 11/26/2019] [Indexed: 01/08/2023]
Abstract
CONTEXT α-klotho is an integral membrane protein that serves as a coreceptor for fibroblast growth factor 23 (FGF23) in conjunction with cognate fibroblast growth factor receptors. Proteolytic cleavage sheds the ectodomain of α-klotho (soluble α-klotho) as an endocrine substance into blood, urine, and cerebrospinal fluid. OBJECTIVE To study the relationship of soluble α-klotho to mineral metabolism in the general population with mainly preserved kidney function. DESIGN Cross-sectional analysis of the associations between soluble α-klotho with laboratory markers of markers of mineral metabolism in a population-based cohort. SETTING Three centers in Switzerland including 1128 participants. MEASURES Soluble full-length α-klotho levels by a specific immunoassay and markers of mineral metabolism. RESULTS The median serum level of soluble α-klotho was 15.0 pmol/L. Multivariable analyses using α-klotho as the outcome variable revealed a sex-by-PTH interaction: In men, PTH was positively associated with α-klotho levels, whereas this association was negative in women. Plasma phosphate associated with soluble α-klotho levels in an age-dependent manner, changing from a positive association in young adults gradually to a negative association in the elderly. The decline of 1,25 (OH)2 vitamin D3 levels in parallel to the gradual impairment of kidney function was greatly attenuated in the setting of high circulating soluble α-klotho levels. CONCLUSIONS Soluble α-klotho level is associated with plasma phosphate in an age-dependent manner and with PTH in a sex-dependent manner. Furthermore, our data reveal soluble α-klotho as a modulator of 1,25 (OH)2 vitamin D3 levels in individuals with preserved renal function.
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Affiliation(s)
- Nasser A Dhayat
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Menno Pruijm
- Nephrology Service, Lausanne University Hospital, Lausanne, Switzerland
| | - Belen Ponte
- Nephrology Service, Department of Specialties of Internal Medicine, Geneva University Hospital, Geneva, Switzerland
| | - Daniel Ackermann
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Alexander Benedikt Leichtle
- Department of Laboratory Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Insel Data Science Center, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Olivier Devuyst
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Georg Ehret
- Cardiology Service, Department of Specialties of Internal Medicine, Geneva University Hospital, Geneva, Switzerland
| | - Idris Guessous
- Division of Primary Care Medicine, Geneva University Hospital, Geneva, Switzerland
| | - Antoinette Pechère-Bertschi
- Endocrinology Service, Department of Specialties of Internal Medicine, Geneva University Hospital, Geneva, Switzerland
| | - Johanne Pastor
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, Department of Physiology and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Pierre-Yves Martin
- Nephrology Service, Department of Specialties of Internal Medicine, Geneva University Hospital, Geneva, Switzerland
| | - Michel Burnier
- Nephrology Service, Lausanne University Hospital, Lausanne, Switzerland
| | - Georg-Martin Fiedler
- Department of Laboratory Medicine, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Bruno Vogt
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Orson W Moe
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, Department of Physiology and Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Murielle Bochud
- Center for Primary Care and Public Health (Unisanté), University of Lausanne, Lausanne, Switzerland
| | - Daniel G Fuster
- Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Correspondence and Reprint Requests: Daniel G. Fuster, Department of Nephrology and Hypertension, Inselspital, Bern University Hospital, University of Bern, Freiburgstrasse 15, 3010 Bern, Switzerland. E-mail:
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11
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Takenaka T, Kobori H, Inoue T, Miyazaki T, Suzuki H, Nishiyama A, Ishii N, Hayashi M. Klotho supplementation ameliorates blood pressure and renal function in DBA/2-pcy mice, a model of polycystic kidney disease. Am J Physiol Renal Physiol 2020; 318:F557-F564. [PMID: 31928223 DOI: 10.1152/ajprenal.00299.2019] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Klotho interacts with various membrane proteins such as receptors for transforming growth factor-β (TGF-β) and insulin-like growth factor (IGF). Renal expression of klotho is diminished in polycystic kidney disease (PKD). In the present study, the effects of klotho supplementation on PKD were assessed. Recombinant human klotho protein (10 μg·kg-1·day-1) or a vehicle was administered daily by subcutaneous injection to 6-wk-old mice with PKD (DBA/2-pcy). Blood pressure was measured using tail-cuff methods. After 2 mo, mice were killed, and the kidneys were harvested for analysis. Exogenous klotho protein supplementation reduced kidney weight, cystic area, systolic blood pressure, renal angiotensin II levels, and 8-epi-PGF2α excretion (P < 0.05). Klotho protein supplementation enhanced glomerular filtration rate, renal expression of superoxide dismutase, and klotho itself (P < 0.05). Klotho supplementation attenuated renal expressions of TGF-β and collagen type I and diminished renal abundance of Twist, phosphorylated Akt, and mammalian target of rapamycin (P < 0.05). Pathological examination revealed that klotho decreased the fibrosis index and nuclear staining of Smad in PKD kidneys (P < 0.05). Our data indicate that klotho protein supplementation ameliorates the renin-angiotensin system, reducing blood pressure in PKD mice. Furthermore, the present results implicate klotho supplementation in the suppression of Akt/mammalian target of rapamycin signaling, slowing cystic expansion. Finally, our findings suggest that klotho protein supplementation attenuated fibrosis at least partly by inhibiting epithelial mesenchymal transition in PKD.
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Affiliation(s)
- Tsuneo Takenaka
- International University of Health and Welfare, Minato, Tokyo
| | - Hiroyuki Kobori
- International University of Health and Welfare, Minato, Tokyo
| | | | | | | | | | - Naohito Ishii
- Kitasato University, Sagamihara, Kanagawa, Tokyo, Japan
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12
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Takenaka T, Inoue T, Miyazaki T, Kobori H, Nishiyama A, Ishii N, Hayashi M, Suzuki H. Klotho Ameliorates Medullary Fibrosis and Pressure Natriuresis in Hypertensive Rat Kidneys. Hypertension 2019; 72:1151-1159. [PMID: 30354813 DOI: 10.1161/hypertensionaha.118.11176] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Renal expression of klotho is reduced in hypertension. Experiments were performed to examine whether exogenous klotho protein supplementation ameliorates pressure natriuresis in early phase of hypertension, using stroke-prone spontaneously hypertensive rats (sp-SHR). The interactions between klotho protein and renal renin-Ang (angiotensin) system were examined with immunoprecipitation and cell culture methods. Uninephrectomy was performed in sp-SHRs to induce nephrosclerosis, and they were treated with exogenous klotho protein or vehicle. Exogenous klotho protein supplementation to sp-SHR decreased blood pressure, renal Ang II levels, AGT (angiotensinogen) expression, HIF (hypoxia-inducible factor)-1α abundance, and medullary fibronectin levels, with increased renal klotho expression and serum and urine klotho levels. Klotho supplementation also reduced kidney weight, renal phosphorylated Akt, and mTOR (mammalian target of rapamycin) abundance. Furthermore, klotho supplementation restored renal autoregulation of glomerular filtration rate and enhanced pressure-induced natriuresis in sp-SHR. Klotho protein bound to AT1R (Ang II type-1 receptor) and decreased the presence of AT1R on HK-2 (human proximal tubular) cells, attenuating inositol triphosphate generation. Klotho protein suppressed Ang II-induced increments of AGT expression in HK-2 cells. Collectively, the present data demonstrate that klotho binds with the AT1R to suppress Ang signal transduction, participating in inactivating renal renin-Ang system. Our results also suggest that exogenous klotho supplementation represses Akt-mTOR signaling to reduce renal hypertrophy and restore the autoregulatory ability of glomerular filtration rate in uninephrectomized sp-SHRs. Finally, the present findings implicate that klotho supplementation inhibits HIF-1α pathway and medullary fibrosis, contributing to enhancements of pressure natriuresis and reduction in blood pressure.
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Affiliation(s)
- Tsuneo Takenaka
- From the Department of Medicine, International University of Health and Welfare, Minato, Tokyo, Japan (T.T., H.K.)
| | - Tsutomu Inoue
- Department of Nephrology, Saitama Medical University, Iruma, Japan (T.I., T.M., H.S.)
| | - Takashi Miyazaki
- Department of Nephrology, Saitama Medical University, Iruma, Japan (T.I., T.M., H.S.)
| | - Hiroyuki Kobori
- From the Department of Medicine, International University of Health and Welfare, Minato, Tokyo, Japan (T.T., H.K.)
| | - Akira Nishiyama
- Department of Pharmacology, Kagawa University, Kita, Japan (A.N.)
| | - Naohito Ishii
- Department of Clinical Chemistry, Kitasato University, Sagamihara, Kanagawa, Japan (N.I.)
| | - Matsuhiko Hayashi
- Blood Purification Center, Keio University, Shinjuku, Tokyo, Japan (M.H.)
| | - Hiromichi Suzuki
- Department of Nephrology, Saitama Medical University, Iruma, Japan (T.I., T.M., H.S.)
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Silva AP, Mendes F, Carias E, Gonçalves RB, Fragoso A, Dias C, Tavares N, Café HM, Santos N, Rato F, Leão Neves P, Almeida E. Plasmatic Klotho and FGF23 Levels as Biomarkers of CKD-Associated Cardiac Disease in Type 2 Diabetic Patients. Int J Mol Sci 2019; 20:E1536. [PMID: 30934737 PMCID: PMC6480092 DOI: 10.3390/ijms20071536] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 03/20/2019] [Accepted: 03/22/2019] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Research over the past decade has focused on the role of Klotho as a cardio protective agent that prevents the effects of aging on the heart and reduces the burden of cardiovascular disease CVD. The role of the interaction between fibroblast growth factor 23-(FGF-23)/Klotho in Klotho-mediated actions is still under debate. The main objective was to ascertain the potential use of plasmatic Klotho and FGF23 as markers for CKD-associated cardiac disease and mortality. METHODS This was a prospective analysis conducted in an outpatient diabetic nephropathy clinic, enrolling 107 diabetic patients with stage 2⁻3 CKD. Patients were divided into three groups according to their left ventricular mass index and relative wall thickness. RESULTS Multinomial regression analysis demonstrated that low Klotho and higher FGF-23 levels were linked to a greater risk of concentric hypertrophy. In the generalized linear model (GLM), Klotho, FGF-23 and cardiac geometry groups were statistically significant as independent variables of cardiovascular hospitalization (p = 0.007). According to the Cox regression model, fatal cardiovascular events were associated with the following cardiac geometric classifications; eccentric hypertrophy (p = 0.050); concentric hypertrophy (p = 0.041), and serum phosphate ≥ 3.6 mg/dL (p = 0.025), FGF-23 ≥ 168 (p = 0.0149), α-klotho < 313 (p = 0.044). CONCLUSIONS In our population, Klotho and FGF23 are associated with cardiovascular risk in the early stages of CKD.
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Affiliation(s)
- Ana Paula Silva
- Nephrology Department, Centro Hospitalar Universitário do Algarve, 800-836 Faro, Portugal.
- Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 8005-139 Faro, Portugal.
| | - Filipa Mendes
- Nephrology Department, Centro Hospitalar Universitário do Algarve, 800-836 Faro, Portugal.
| | - Eduarda Carias
- Nephrology Department, Centro Hospitalar Universitário do Algarve, 800-836 Faro, Portugal.
| | - Rui Baptista Gonçalves
- Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 8005-139 Faro, Portugal.
| | - André Fragoso
- Nephrology Department, Centro Hospitalar Universitário do Algarve, 800-836 Faro, Portugal.
| | - Carolina Dias
- Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 8005-139 Faro, Portugal.
| | - Nelson Tavares
- Cardiology Department, Centro Hospitalar Universitário do Algarve, 8000-386 Faro, Portugal.
| | - Hugo Mendonça Café
- Cardiology Department, Centro Hospitalar Universitário do Algarve, 8000-386 Faro, Portugal.
| | - Nélio Santos
- Clinic Pathology Department, Centro Hospitalar Universitário do Algarve, 8000-836, Faro, Portugal.
| | - Fátima Rato
- Clinic Pathology Department, Centro Hospitalar Universitário do Algarve, 8000-836, Faro, Portugal.
| | - Pedro Leão Neves
- Nephrology Department, Centro Hospitalar Universitário do Algarve, 800-836 Faro, Portugal.
- Departamento de Ciências Biomédicas e Medicina, Universidade do Algarve, 8005-139 Faro, Portugal.
| | - Edgar Almeida
- Faculdadade de Medicina da Universidade de Lisboa, 1600-190 Lisboa, Portugal.
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14
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Takenaka T, Kobori H, Miyazaki T, Suzuki H, Nishiyama A, Ishii N, Yamashita M, Hayashi M. Klotho protein supplementation reduces blood pressure and renal hypertrophy in db/db mice, a model of type 2 diabetes. Acta Physiol (Oxf) 2019; 225:e13190. [PMID: 30251773 DOI: 10.1111/apha.13190] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 09/19/2018] [Accepted: 09/19/2018] [Indexed: 12/18/2022]
Abstract
AIMS Klotho interacts with various membrane proteins, such as receptors for transforming growth factor (TGF)-β and insulin-like growth factor (IGF), to alter their function. Renal expression of klotho is diminished in diabetes. The present study examined whether exogenous klotho protein supplementation ameliorates kidney injury and renin-angiotensin system (RAS) in db/db mice. METHODS We investigated the effects of klotho supplementation on diabetic kidney injury and RAS. Recombinant human klotho protein (10 μg/kg/d) was administered to db/db mice daily. RESULTS Klotho protein supplementation reduced kidney weight, systolic blood pressure (SBP), albuminuria, glomerular filtration rate, and 8-epi-prostaglandin F2α excretion without affecting body weight. Although klotho supplementation did not alter glycated albumin, it reduced renal angiotensin II levels associated with reduced renal expression of angiotensinogen. Klotho supplementation improved renal expression of superoxide dismutase (SOD), and endogenous renal expression of klotho. Klotho supplementation reduced the levels of hypoxia-inducible factor, phosphorylated Akt, and phosphorylated mTOR and decreased the renal expression of TGF-β, tumour necrosis factor (TNF), and fibronectin. CONCLUSIONS These data indicate that klotho supplementation reduces blood pressure and albuminuria along with ameliorating renal RAS activation in db/db mice. Furthermore, these results suggest that klotho inhibits IGF signalling, induces SOD expression to reduce oxidative stress, and suppresses Akt-mTOR signalling to inhibit abnormal kidney growth. Collectively, the results suggest that klotho inhibits TGF-β and TNF signalling, resulting in a decline in renal fibrosis.
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Affiliation(s)
- Tsuneo Takenaka
- International University of Health and Welfare; Minato Japan
| | - Hiroyuki Kobori
- International University of Health and Welfare; Minato Japan
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Abstract
Chronic kidney disease (CKD) is an inherently systemic disease that refers to a long-term loss of kidney function. The progression of CKD has repercussions for other organs, leading to many kinds of extrarenal complications. Intensive studies are now being undertaken to reveal the risk factors and pathophysiological mechanism of this disease. During the past 20 years, increasing evidence from clinical and basic studies has indicated that klotho, which was initially known as an anti-aging gene and is mainly expressed in the kidney, is significantly correlated with the development and progression of CKD and its complications. Here, we discuss in detail the role and pathophysiological implications of klotho in ion disorders, the inflammation response, vascular calcification, mineral bone disorders, and renal fibrosis in CKD. Based on the pathogenic mechanism of klotho deficiency and klotho decline in urine early in CKD stage 2 and even earlier in CKD stage 1, it is not difficult to understand that soluble klotho can serve as an early and sensitive marker of CKD. Moreover, the prevention of klotho decline by several mechanisms can attenuate renal injuries, retard CKD progression, ameliorate extrarenal complications, and improve renal function. In this review, we focus on the functions and pathophysiological implications of klotho in CKD and its extrarenal complications as well as its potential applications as a diagnostic and/or prognostic biomarker for CKD and as a novel treatment strategy to improve and decrease the burden of comorbidity in CKD.
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16
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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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He X, Shen Y, Ma X, Ying L, Peng J, Pan X, Bao Y, Zhou J. The association of serum FGF23 and non-alcoholic fatty liver disease is independent of vitamin D in type 2 diabetes patients. Clin Exp Pharmacol Physiol 2018; 45:668-674. [PMID: 29574933 DOI: 10.1111/1440-1681.12933] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 03/07/2018] [Accepted: 03/08/2018] [Indexed: 02/06/2023]
Abstract
Recent studies have shown that circulating fibroblast growth factor (FGF) 23 and vitamin D levels are closely correlated with insulin resistance. The aim of this study was to investigate the relationship among serum FGF 23 levels, serum 25-hydroxyvitamin D [25(OH)D] levels, and non-alcoholic fatty liver disease (NAFLD) in Chinese patients with type 2 diabetes mellitus (T2DM). This study enrolled 331 hospitalized T2DM patients (209 patients with NAFLD and 122 patients without NAFLD). Serum FGF23 levels were measured using a sandwich enzyme-linked immunosorbent assay. Serum 25(OH)D levels were determined by an electrochemiluminescence immunoassay. NAFLD was diagnosed by hepatic ultrasound, and the fatty liver index (FLI) was calculated to quantify hepatic steatosis. Results showed that T2DM patients with NAFLD had significantly higher serum FGF23 levels (44.17 [37.92-51.30] pg/mL vs 40.21 [34.07-48.33] pg/mL, P = .002), but lower serum 25(OH)D levels (16.43 [12.70-21.37] ng/mL vs 19.59 [13.78-26.26] ng/mL, P = .002) than those without NAFLD. Moreover, the incidence rate of NAFLD increased with increasing serum FGF23 levels and decreased with increasing 25(OH)D levels (both P < .05). Logistic regression analysis showed that both serum FGF23 and 25(OH)D levels were independent factors for NAFLD (both P < .05). Furthermore, a multiple stepwise regression analysis also revealed that both serum FGF23 and 25(OH)D levels were independently correlated with FLI (both P < .01). In conclusion, both high FGF23 and low vitamin D levels showed an independent relationship with NAFLD in Chinese T2DM patients, indicating that FGF23 and vitamin D function via different regulatory pathways in the liver.
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Affiliation(s)
- Xingxing He
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Yun Shen
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Xiaojing Ma
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Lingwen Ying
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Jiahui Peng
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Xiaoping Pan
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Yuqian Bao
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Jian Zhou
- Department of Endocrinology and Metabolism, Shanghai Clinical Center for Diabetes, Shanghai Key Laboratory of Diabetes Mellitus, Shanghai Diabetes Institute, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
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18
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Bajwa NM, Sanchez CP, Lindsey RC, Watt H, Mohan S. Cortical and trabecular bone are equally affected in rats with renal failure and secondary hyperparathyroidism. BMC Nephrol 2018; 19:24. [PMID: 29394885 PMCID: PMC5796449 DOI: 10.1186/s12882-018-0822-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 01/21/2018] [Indexed: 12/31/2022] Open
Abstract
Background Changes in mineral metabolism and bone structure develop early in the course of chronic kidney disease and at end-stage are associated with increased risk of fragility fractures. The disruption of phosphorus homeostasis leads to secondary hyperparathyroidism, a common complication of chronic kidney disease. However, the molecular pathways by which high phosphorus influences bone metabolism in the early stages of the disease are not completely understood. We investigated the effects of a high phosphorus diet on bone and mineral metabolism using a 5/6 nephrectomy model of chronic kidney disease. Methods Four-week old rats were randomly assigned into groups: 1) Control with standard diet, 2) Nephrectomy with standard rodent diet, and 3) Nephrectomy with high phosphorus diet. Rats underwent in vivo imaging at baseline, day 14, and day 28, followed by ex vivo imaging. Results Cortical bone density at the femoral mid-diaphysis was reduced in nephrectomy-control and nephrectomy-high phosphorus compared to control rats. In contrast, trabecular bone mass was reduced at both the lumbar vertebrae and the femoral secondary spongiosa in nephrectomy-high phosphorus but not in nephrectomy-control. Reduced trabecular bone volume adjusted for tissue volume was caused by changes in trabecular number and separation at day 35. Histomorphometry revealed increased bone resorption in tibial secondary spongiosa in nephrectomy-control. High phosphorus diet-induced changes in bone microstructure were accompanied by increased serum parathyroid hormone and fibroblast growth factor 23 levels. Conclusion Our study demonstrates that changes in mineral metabolism and hormonal dysfunction contribute to trabecular and cortical bone changes in this model of early chronic kidney disease.
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Affiliation(s)
- Nikita M Bajwa
- Musculoskeletal Disease Center, VA Loma Linda Healthcare System, 11201 Benton Street, Loma Linda, CA, 92357, USA
| | - Cheryl P Sanchez
- Department of Pediatrics, Loma Linda University, Loma Linda, CA, 92354, USA
| | - Richard C Lindsey
- Musculoskeletal Disease Center, VA Loma Linda Healthcare System, 11201 Benton Street, Loma Linda, CA, 92357, USA
| | - Heather Watt
- Musculoskeletal Disease Center, VA Loma Linda Healthcare System, 11201 Benton Street, Loma Linda, CA, 92357, USA
| | - Subburaman Mohan
- Musculoskeletal Disease Center, VA Loma Linda Healthcare System, 11201 Benton Street, Loma Linda, CA, 92357, USA. .,Department of Medicine, Loma Linda University, Loma Linda, CA, 92354, USA. .,Department of Orthopedic Surgery, Loma Linda University, Loma Linda, CA, 92354, USA.
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19
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Takenaka T, Inoue T, Miyazaki T, Kobori H, Nishiyama A, Ishii N, Hayashi M, Suzuki H. Klotho suppresses the renin-angiotensin system in adriamycin nephropathy. Nephrol Dial Transplant 2018; 32:791-800. [PMID: 27798196 DOI: 10.1093/ndt/gfw340] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/10/2016] [Indexed: 11/13/2022] Open
Abstract
Backgrounds Klotho protein interacts with the transforming growth factor β (TGF-β) receptor and Wnt, which contribute to the progression of renal disease, inhibiting their signals. Renal and circulating klotho levels are diminished in chronic kidney disease. Methods Experiments were performed to assess whether supplementation of klotho protein could have protective effects on the kidney. Rats were injected with adriamycin (5 mg/kg) and divided into three groups: those treated with vehicle, those treated with klotho protein and those treated with klotho plus 4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione (TDZD). Rats without adriamycin treatment were used as a control. Results Adriamycin reduced the serum klotho concentration and renal expression of klotho and E-cadherin. Adriamycin also increased the renal expression of Wnt, TGF-β, and angiotensinogen, as well as the renal abundance of β-catenin and angiotensin II. Klotho supplementation suppressed adriamycin-induced elevations of β-catenin and angiotensin II with sustained Wnt expression. Combined treatment with klotho and TDZD reversed the klotho-induced improvements in the renal abundance of β-catenin and angiotensin II as well as the expression of TGF-β and angiotensinogen without affecting E-cadherin. Conclusions Our data indicate that Wnt is involved in the pathogenesis of adriamycin nephropathy. Furthermore, klotho supplementation inhibited Wnt signaling, ameliorating renal angiotensin II. Finally, klotho protein appears to suppress epithelial-mesenchymal transition by inhibiting TGF-β and Wnt signaling.
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Affiliation(s)
- Tsuneo Takenaka
- Department of Medicine, International University of Health and Welfare, 8-10-16 Akasaka, Minato, Tokyo 107-0052, Japan
| | - Tsutomu Inoue
- Department of Nephrology, Saitama Medical University, Iruma, Saitama, Japan
| | - Takashi Miyazaki
- Department of Nephrology, Saitama Medical University, Iruma, Saitama, Japan
| | - Hiroyuki Kobori
- Department of Medicine, International University of Health and Welfare, 8-10-16 Akasaka, Minato, Tokyo 107-0052, Japan
| | - Akira Nishiyama
- Department of Pharmacology, Kagawa University, Kida, Kagawa, Japan
| | - Naohito Ishii
- Department of Clinical Chemistry, Kitasato University, Sagamihara, Kanagawa, Japan
| | | | - Hiromichi Suzuki
- Department of Nephrology, Saitama Medical University, Iruma, Saitama, Japan
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20
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Olauson H, Mencke R, Hillebrands JL, Larsson TE. Tissue expression and source of circulating αKlotho. Bone 2017; 100:19-35. [PMID: 28323144 DOI: 10.1016/j.bone.2017.03.043] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 03/15/2017] [Accepted: 03/16/2017] [Indexed: 12/16/2022]
Abstract
αKlotho (Klotho), a type I transmembrane protein and a coreceptor for Fibroblast Growth Factor-23, was initially thought to be expressed only in a limited number of tissues, most importantly the kidney, parathyroid gland and choroid plexus. Emerging data may suggest a more ubiquitous Klotho expression pattern which has prompted reevaluation of the restricted Klotho paradigm. Herein we systematically review the evidence for Klotho expression in various tissues and cell types in humans and other mammals, and discuss potential reasons behind existing conflicting data. Based on current literature and tissue expression atlases, we propose a classification of tissues into high, intermediate and low/absent Klotho expression. The functional relevance of Klotho in organs with low expression levels remain uncertain and there is currently limited data on a role for membrane-bound Klotho outside the kidney. Finally, we review the evidence for the tissue source of soluble Klotho, and conclude that the kidney is likely to be the principal source of circulating Klotho in physiology.
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Affiliation(s)
- Hannes Olauson
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.
| | - Rik Mencke
- Division of Pathology, Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Jan-Luuk Hillebrands
- Division of Pathology, Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Tobias E Larsson
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
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21
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Neyra JA, Hu MC. Potential application of klotho in human chronic kidney disease. Bone 2017; 100:41-49. [PMID: 28115282 PMCID: PMC5474175 DOI: 10.1016/j.bone.2017.01.017] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 01/18/2017] [Accepted: 01/18/2017] [Indexed: 01/13/2023]
Abstract
The extracellular domain of transmembrane alpha-Klotho (αKlotho, hereinafter simply called Klotho) is cleaved by secretases and released into the circulation as soluble Klotho. Soluble Klotho in the circulation starts to decline early in chronic kidney disease (CKD) stage 2 and urinary Klotho possibly even earlier in CKD stage 1. Therefore soluble Klotho could serve as an early and sensitive marker of kidney function decline. Moreover, preclinical animal data support Klotho deficiency is not just merely a biomarker, but a pathogenic factor for CKD progression and extrarenal CKD complications including cardiovascular disease and disturbed mineral metabolism. Prevention of Klotho decline, re-activation of endogenous Klotho production or supplementation of exogenous Klotho are all associated with attenuation of renal fibrosis, retardation of CKD progression, improvement of mineral metabolism, amelioration of cardiomyopathy, and alleviation of vascular calcification in CKD. Therefore Klotho is not only a diagnostic and/or prognostic marker for CKD, but the treatment of Klotho deficiency may be a promising strategy to prevent, retard, and decrease the burden of comorbidity in CKD.
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Affiliation(s)
- Javier A Neyra
- Department of Internal Medicine, University of Texas Southwestern Medical Center, USA; Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, USA
| | - Ming Chang Hu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, USA; Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, USA.
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22
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Evenepoel P, Bover J, Ureña Torres P. Parathyroid hormone metabolism and signaling in health and chronic kidney disease. Kidney Int 2016; 90:1184-1190. [PMID: 27653840 DOI: 10.1016/j.kint.2016.06.041] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Revised: 06/24/2016] [Accepted: 06/27/2016] [Indexed: 11/25/2022]
Abstract
Circulating parathyroid hormone (PTH) shows a complex relationship with hard outcomes in subjects with chronic kidney disease (CKD). Moreover, intervention studies directly targeting PTH failed to yield unequivocal results. Disturbed PTH metabolism, posttranslational modifications of PTH, and end-organ hyporesponsiveness to PTH may explain the poor performance of PTH as an outcome biomarker and precise target of therapy in the setting of CKD, at least in the gray middle target zone. PTH fragments accumulate in CKD patients and may exert effects that are distinct from, if not opposite to biointact (1-84)PTH. Posttranslational modification of PTH and especially oxidation may alter the interaction of PTH with its receptor. Its clinical relevance, however, remains a matter of ongoing debate. Less controversial is the issue of end-organ hyporesponsiveness to PTH. This phenomenon, formally referred to as PTH resistance, has long been recognized in CKD, but factors and mechanisms contributing to it remain poorly defined. Subsequent evidence identified downregulation of the PTH receptor and competing downstream signals as underlying pathophysiologic mechanisms. End-organ hyporesponsiveness to PTH in CKD, along with important analytical and biological variability, renders defining the PTH target range in CKD challenging. Although this may still be accomplished at the population level, it may prove to be very difficult at the individual level. This is a disillusioning thought in an era of personalized medicine. Parallel to the search of a functional and readily available assay quantifying PTH signaling tone or sensitivity, additional biomarkers (or a panel of biomarkers) should be formally evaluated.
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Affiliation(s)
- Pieter Evenepoel
- KU Leuven, Department of Immunology and Microbiology, Laboratory of Nephrology and University Hospitals Leuven, Department of Nephrology and Renal Transplantation, B-3000 Leuven, Belgium; Board member of the ERA-EDTA CKD-MBD Working Group.
| | - Jordi Bover
- Fundació Puigvert, Department of Nephrology, IIB Sant Pau, RedinREn, Barcelona, Catalonia, Spain; Board member of the ERA-EDTA CKD-MBD Working Group
| | - Pablo Ureña Torres
- Ramsay-Générale de Santé, Clinique du Landy, Service de Néphrologie-Dialyse, Saint Ouen, France, INSERM U1151-CNRS UMR8253 Université Paris Descartes, and Service des Explorations Fonctionnelles, Hôpital Necker-Enfants Malades, Paris, France; Board member of the ERA-EDTA CKD-MBD Working Group
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23
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Evenepoel P, Naesens M. Mineral metabolism disturbances in kidney donors: smoke, no fire (yet). Kidney Int 2016; 90:734-6. [PMID: 27633867 DOI: 10.1016/j.kint.2016.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 06/15/2016] [Accepted: 06/20/2016] [Indexed: 11/26/2022]
Abstract
Kasiske and colleagues studied mineral and bone metabolism after unilateral donor nephrectomy. Similar as to what is observed early in the course of chronic kidney disease, fibroblast growth factor 23 and parathyroid hormone concentrations were shown to be increased following kidney donation. High fibroblast growth factor 23 and parathyroid hormone concentrations most probably are a compensatory mechanism to maintain normophosphatemia. Bone biomarker profiles in the study suggest increased bone turnover as trade-off. Limitations inherent to the assessed biomarkers, however, warrant a prudent interpretation.
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Affiliation(s)
- Pieter Evenepoel
- KU Leuven, Department of Immunology and Microbiology, Laboratory of Nephrology, B-3000 Leuven, Belgium.
| | - Maarten Naesens
- KU Leuven, Department of Immunology and Microbiology, Laboratory of Nephrology, B-3000 Leuven, Belgium
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24
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Sneddon WB, Ruiz GW, Gallo LI, Xiao K, Zhang Q, Rbaibi Y, Weisz OA, Apodaca GL, Friedman PA. Convergent Signaling Pathways Regulate Parathyroid Hormone and Fibroblast Growth Factor-23 Action on NPT2A-mediated Phosphate Transport. J Biol Chem 2016; 291:18632-42. [PMID: 27432882 PMCID: PMC5009241 DOI: 10.1074/jbc.m116.744052] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Indexed: 12/18/2022] Open
Abstract
Parathyroid hormone (PTH) and FGF23 are the primary hormones regulating acute phosphate homeostasis. Human renal proximal tubule cells (RPTECs) were used to characterize the mechanism and signaling pathways of PTH and FGF23 on phosphate transport and the role of the PDZ protein NHERF1 in mediating PTH and FGF23 effects. RPTECs express the NPT2A phosphate transporter, αKlotho, FGFR1, FGFR3, FGFR4, and the PTH receptor. FGFR1 isoforms are formed from alternate splicing of exon 3 and of exon 8 or 9 in Ir-like loop 3. Exon 3 was absent, but mRNA containing both exons 8 and 9 is present in cytoplasm. Using an FGFR1c-specific antibody together with mass spectrometry analysis, we show that RPTECs express FGFR-β1C. The data are consistent with regulated FGFR1 splicing involving a novel cytoplasmic mechanism. PTH and FGF23 inhibited phosphate transport in a concentration-dependent manner. At maximally effective concentrations, PTH and FGF23 equivalently decreased phosphate uptake and were not additive, suggesting a shared mechanism of action. Protein kinase A or C blockade prevented PTH but not FGF23 actions. Conversely, inhibiting SGK1, blocking FGFR dimerization, or knocking down Klotho expression disrupted FGF23 actions but did not interfere with PTH effects. C-terminal FGF23(180-251) competitively and selectively blocked FGF23 action without disrupting PTH effects. However, both PTH and FGF23-sensitive phosphate transport were abolished by NHERF1 shRNA knockdown. Extended treatment with PTH or FGF23 down-regulated NPT2A without affecting NHERF1. We conclude that FGFR1c and PTHR signaling pathways converge on NHERF1 to inhibit PTH- and FGF23-sensitive phosphate transport and down-regulate NPT2A.
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MESH Headings
- Cell Line, Transformed
- Fibroblast Growth Factor-23
- Fibroblast Growth Factors/genetics
- Fibroblast Growth Factors/metabolism
- Glucuronidase/biosynthesis
- Glucuronidase/genetics
- Humans
- Klotho Proteins
- Parathyroid Hormone/genetics
- Parathyroid Hormone/metabolism
- Phosphates/metabolism
- Phosphoproteins/genetics
- Phosphoproteins/metabolism
- Receptor, Fibroblast Growth Factor, Type 1/genetics
- Receptor, Fibroblast Growth Factor, Type 1/metabolism
- Receptor, Fibroblast Growth Factor, Type 3/biosynthesis
- Receptor, Fibroblast Growth Factor, Type 3/genetics
- Receptor, Fibroblast Growth Factor, Type 4/biosynthesis
- Receptor, Fibroblast Growth Factor, Type 4/genetics
- Receptor, Parathyroid Hormone, Type 1/genetics
- Receptor, Parathyroid Hormone, Type 1/metabolism
- Signal Transduction/physiology
- Sodium-Hydrogen Exchangers/genetics
- Sodium-Hydrogen Exchangers/metabolism
- Sodium-Phosphate Cotransporter Proteins, Type IIa/genetics
- Sodium-Phosphate Cotransporter Proteins, Type IIa/metabolism
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Affiliation(s)
- W Bruce Sneddon
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology and
| | - Giovanni W Ruiz
- Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Luciana I Gallo
- Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Kunhong Xiao
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology and
| | - Qiangmin Zhang
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology and
| | - Youssef Rbaibi
- Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Ora A Weisz
- Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 Cell Biology, and
| | - Gerard L Apodaca
- Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 Cell Biology, and
| | - Peter A Friedman
- From the Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology and the Departments of Structural Biology,
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25
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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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