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Evenepoel P, Jørgensen HS. Skeletal parathyroid hormone hyporesponsiveness: a neglected, but clinically relevant reality in chronic kidney disease. Curr Opin Nephrol Hypertens 2024; 33:383-390. [PMID: 38651491 DOI: 10.1097/mnh.0000000000000992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
PURPOSE OF REVIEW Defining the optimal parathyroid hormone (PTH) target in chronic kidney disease (CKD) is challenging, especially for bone outcomes, due to the substantial variability in the skeleton's response to PTH. Although PTH hyporesponsiveness is as integral a component of CKD-mineral bone disorder as elevated PTH levels, clinical awareness of this condition is limited. In this review, we will discuss factors and mechanisms contributing to PTH hyporesponsiveness in CKD. This knowledge may provide clues towards a personalized approach to treating secondary hyperparathyroidism in CKD. RECENT FINDINGS Indicates a link between disturbed phosphate metabolism and impaired skeletal calcium sensing receptor signaling as an important mediator of PTH hyporesponsiveness in CKD. Further, cohort studies with diverse populations point towards differences in mineral metabolism control, rather than genetic or environmental factors, as drivers of the variability of PTH responsiveness. IN SUMMARY Skeletal PTH hyporesponsiveness in CKD has a multifactorial origin, shows important interindividual variability, and is challenging to estimate in clinical practice. The variability in skeletal responsiveness compromises PTH as a biomarker of bone turnover, especially when considering populations that are heterogeneous in ethnicity, demography, kidney function, primary kidney disease and mineral metabolism control, and in patients treated with bone targeting drugs.
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Affiliation(s)
- Pieter Evenepoel
- Department of Immunology and Transplantation, Nephrology and Renal Transplantation Research Group, KU Leuven, Belgium
- Department of Medicine, Division of Nephrology, Leuven University Hospitals, Leuven, Belgium
| | - Hanne Skou Jørgensen
- Institute of Clinical Medicine, Aarhus University, Aarhus
- Department of Nephrology, Aalborg University Hospital, Aalborg, Denmark
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2
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Yiang GT, Su WL, Zheng CM, Liao MT, Cheng TH, Lu CL, Lu KC. The influence of uremic toxins on low bone turnover disease in chronic kidney disease. Tzu Chi Med J 2024; 36:38-45. [PMID: 38406573 PMCID: PMC10887346 DOI: 10.4103/tcmj.tcmj_212_23] [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: 08/27/2023] [Revised: 09/11/2023] [Accepted: 09/28/2023] [Indexed: 02/27/2024] Open
Abstract
Uremic toxins play a crucial role in the development of low bone turnover disease in chronic kidney disease (CKD) through the induction of oxidative stress. This oxidative stress disrupts the delicate balance between bone formation and resorption, resulting in a decline in both bone quantity and quality. Reactive oxygen species (ROS) activate nuclear factor kappa-B and mitogen-activated protein kinase signaling pathways, promoting osteoclastogenesis. Conversely, ROS hinder osteoblast differentiation by facilitating the binding of Forkhead box O proteins (FoxOs) to β-catenin, triggering apoptosis through FoxOs-activating kinase phosphorylation. This results in increased osteoblastic receptor activator of nuclear factor kappa-B ligand (RANKL) expression and decreased nuclear factor erythroid 2-related factor 2 levels, compromising antioxidant defenses against oxidative damage. As CKD progresses, the accumulation of protein-bound uremic toxins such as indoxyl sulfate (IS) and p-cresyl sulfate (PCS) intensifies oxidative stress, primarily affecting osteoblasts. IS and PCS directly inhibit osteoblast viability, induce apoptosis, decrease alkaline phosphatase activity, and impair collagen 1 and osteonectin, impeding bone formation. They also reduce cyclic adenosine 3',5'-monophosphate (cAMP) production and lower parathyroid hormone (PTH) receptor expression in osteoblasts, resulting in PTH hyporesponsiveness. In summary, excessive production of ROS by uremic toxins not only reduces the number and function of osteoblasts but also induces PTH hyporesponsiveness, contributing to the initiation and progression of low bone turnover disease in CKD.
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Affiliation(s)
- Giou-Teng Yiang
- School of Medicine, Tzu Chi University, Hualien, Taiwan
- Department of Emergency Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei, Taiwan
| | - Wen-Lin Su
- School of Medicine, Tzu Chi University, Hualien, Taiwan
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei, Taiwan
| | - Cai-Mei Zheng
- Division of Nephrology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
- Division of Nephrology, Department of Internal Medicine, Taipei Medical University Shuang Ho Hospital, New Taipei, Taiwan
- Taipei Medical University-Research Center of Urology and Kidney, Taipei Medical University, Taipei, Taiwan
| | - Min-Tser Liao
- Department of Pediatrics, Taoyuan Armed Forces General Hospital, Taoyuan, Taiwan
- Department of Pediatrics, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Tong-Hong Cheng
- Department of Internal Medicine, Taoyuan Armed Forces General Hospital, Taoyuan, Taiwan
| | - Chien-Lin Lu
- School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei, Taiwan
- Division of Nephrology, Department of Medicine, Fu Jen Catholic University Hospital, New Taipei, Taiwan
| | - Kuo-Cheng Lu
- Division of Nephrology, Department of Medicine, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei, Taiwan
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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: 1] [Impact Index Per Article: 0.3] [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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Zhao G, Kim EW, Jiang J, Bhoot C, Charles KR, Baek J, Mohan S, Adams JS, Tetradis S, Lyons KM. CCN1/Cyr61 Is Required in Osteoblasts for Responsiveness to the Anabolic Activity of PTH. J Bone Miner Res 2020; 35:2289-2300. [PMID: 32634285 PMCID: PMC9361511 DOI: 10.1002/jbmr.4128] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/24/2020] [Accepted: 07/02/2020] [Indexed: 12/11/2022]
Abstract
CCN1/Cyr61 is a dynamically expressed matricellular protein that serves regulatory functions in multiple tissues. Previous studies from our laboratory demonstrated that CCN1 regulates bone maintenance. Using an osteoblast and osteocyte conditional knockout mouse model (Ccn1OCN ), we found a significant decrease in trabecular and cortical bone mass in vivo, in part through suppression of Wnt signaling since the expression of the Wnt antagonist sclerostin (SOST) is increased in osteoblasts lacking CCN1. It has been established that parathyroid hormone (PTH) signaling also suppresses SOST expression in bone. We therefore investigated the interaction between CCN1 and PTH-mediated responses in this study. We find that loss of Ccn1 in osteoblasts leads to impaired responsiveness to anabolic intermittent PTH treatment in Ccn1OCN mice in vivo and in osteoblasts from these mice in vitro. Analysis of Ccn1OCN mice demonstrated a significant decrease in parathyroid hormone receptor-1 (PTH1R) expression in osteoblasts in vivo and in vitro. We investigated the regulatory role of a non-canonical integrin-binding domain of CCN1 because several studies indicate that specific integrins are critical to mechanotransduction, a PTH-dependent response, in bone. These data suggest that CCN1 regulates the expression of PTH1R through interaction with the αvβ3 and/or αvβ5 integrin complexes. Osteoblasts that express a mutant form of CCN1 that cannot interact with αvβ3/β5 integrin demonstrate a significant decrease in mRNA and protein expression of both PTH1R and αv integrin. Overall, these data suggest that the αvβ3/β5-binding domain of CCN1 is required to endow PTH signaling with anabolic activity in bone cells. © 2020 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Gexin Zhao
- Department of Orthopaedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Elliot W Kim
- Department of Orthopaedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Jie Jiang
- Orthopaedic Institution for Children Foundation, Hemophilia Treatment Center, University of California, Los Angeles, Los Angeles, CA, USA
| | - Chimay Bhoot
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Kemberly R Charles
- Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Jongseung Baek
- Department of Orthopaedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Subburaman Mohan
- Musculoskeletal Disease Center, VA Loma Linda Healthcare Systems, Loma Linda, CA, USA
| | - John S Adams
- Department of Orthopaedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Sotirios Tetradis
- School of Dentistry, University of California, Los Angeles, Los Angeles, CA, USA
| | - Karen M Lyons
- Department of Orthopaedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.,Department of Molecular Cell and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, USA
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Lu CL, Yeih DF, Hou YC, Jow GM, Li ZY, Liu WC, Zheng CM, Lin YF, Shyu JF, Chen R, Huang CY, Lu KC. The Emerging Role of Nutritional Vitamin D in Secondary Hyperparathyroidism in CKD. Nutrients 2018; 10:nu10121890. [PMID: 30513912 PMCID: PMC6316278 DOI: 10.3390/nu10121890] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 11/22/2018] [Accepted: 11/23/2018] [Indexed: 12/18/2022] Open
Abstract
In chronic kidney disease (CKD), hyperphosphatemia induces fibroblast growth factor-23 (FGF-23) expression that disturbs renal 1,25-dihydroxy vitamin D (1,25D) synthesis; thereby increasing parathyroid hormone (PTH) production. FGF-23 acts on the parathyroid gland (PTG) to increase 1α-hydroxylase activity and results in increase intra-gland 1,25D production that attenuates PTH secretion efficiently if sufficient 25D are available. Interesting, calcimimetics can further increase PTG 1α-hydroxylase activity that emphasizes the demand for nutritional vitamin D (NVD) under high PTH status. In addition, the changes in hydroxylase enzyme activity highlight the greater parathyroid 25-hydroxyvitmain D (25D) requirement in secondary hyperparathyroidism (SHPT); the higher proportion of oxyphil cells as hyperplastic parathyroid progression; lower cytosolic vitamin D binding protein (DBP) content in the oxyphil cell; and calcitriol promote vitamin D degradation are all possible reasons supports nutritional vitamin D (NVD; e.g., Cholecalciferol) supplement is crucial in SHPT. Clinically, NVD can effectively restore serum 25D concentration and prevent the further increase in PTH level. Therefore, NVD might have the benefit of alleviating the development of SHPT in early CKD and further lowering PTH in moderate to severe SHPT in dialysis patients.
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Affiliation(s)
- Chien-Lin Lu
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Dong-Feng Yeih
- Division of Cardiology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Yi-Chou Hou
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Medicine, Cardinal-Tien Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 23155, Taiwan.
| | - Guey-Mei Jow
- Division of Nephrology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Zong-Yu Li
- Division of Nephrology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
| | - Wen-Chih Liu
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Internal Medicine, Tungs' Taichung MetroHarbor Hospital, Taichung City 433, Taiwan.
| | - Cai-Mei Zheng
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Internal Medicine, Shuang Ho Hospital, New Taipei City 235, Taiwan.
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11103, Taiwan.
| | - Yuh-Feng Lin
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Internal Medicine, Shuang Ho Hospital, New Taipei City 235, Taiwan.
- Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11103, Taiwan.
| | - Jia-Fwu Shyu
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Department of Biology and Anatomy, National Defense Medical Center, Taipei 114, Taiwan.
| | - Remy Chen
- Kidney Dialysis Center, Kamifukuoka General Hospital, Saitama 356, Japan.
| | - Chung-Yu Huang
- Department of Medicine, Show-Chwan Memorial Hospital, Changhua 50008, Taiwan.
| | - Kuo-Cheng Lu
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan.
- Division of Nephrology, Department of Medicine, Fu Jen Catholic University Hospital, School of Medicine, Fu Jen Catholic University, New Taipei City 242, Taiwan.
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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: 104] [Impact Index Per Article: 13.0] [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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8
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London GM, Marchais SJ, Guérin AP, de Vernejoul MC. Ankle-brachial index and bone turnover in patients on dialysis. J Am Soc Nephrol 2014; 26:476-83. [PMID: 25231881 DOI: 10.1681/asn.2014020169] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
An association between atherosclerosis and osteoporosis has been reported in several studies. This association could result from local intraosseous atherosclerosis and ischemia, which is shown by limb osteoporosis in patients with peripheral artery disease (PAD), but also could result from bidirectional communication between the skeleton and blood vessels. Systemic bone disorders and PAD are frequent in ESRD. Here, we investigated the possible interaction of these disorders. For 65 prevalent nondiabetic patients on hemodialysis, we measured ankle-brachial pressure index (ABix) and evaluated mineral and bone disorders with bone histomorphometry. In prevalent patients on hemodialysis, PAD (ABix<0.9 or >1.4/incompressible) was associated with low bone turnover and pronounced osteoblast resistance to parathyroid hormone (PTH), which is indicated by decreased double-labeled surface and osteoblast surface (P<0.001). Higher osteoblast resistance to PTH in patients with PAD was characterized by weaker correlation coefficients (slopes) between serum PTH and double-labeled surface (P=0.02) or osteoblast surface (P=0.03). The correlations between osteoclast number or eroded surface and serum mineral parameters, including PTH, did not differ for subjects with normal ABix and PAD. Common vascular risk factors (dyslipidemia, smoking, and sex) were similar for normal, low, and incompressible ABix. Patients with PAD were older and had high C-reactive protein levels and longer hemodialysis vintage. These results indicate that, in prevalent nondiabetic patients with ESRD, PAD associates with low bone turnover and pronounced osteoblast resistance to PTH.
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Affiliation(s)
- Gérard M London
- Department of Nephrology, Manhès Hospital, Fleury Mérogis, France; Department of Pharmacology, Georges Pompidou European Hospital, National Institute of Health and Medical Research U970, Paris, France; and
| | | | - Alain P Guérin
- Department of Pharmacology, Georges Pompidou European Hospital, National Institute of Health and Medical Research U970, Paris, France; and
| | - Marie-Christine de Vernejoul
- Lariboisiere Hospital, Vigot Petersen Centre, National Institute of Health and Medical Research U606, University Paris 7, Paris, France
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Abstract
Chronic kidney disease-mineral and bone disorder (CKD-MBD) is characterized by bone abnormalities, vascular calcification, and an array of laboratory abnormalities. The latter classically include disturbances in the parathyroid hormone/vitamin D axis. More recently, fibroblast growth factor 23 (FGF23) and klotho also have been identified as important regulators of mineral metabolism. Klotho deficiency and high circulating FGF23 levels precede secondary hyperparathyroidism in CKD patients. Levels of FGF23 and parathyroid hormone increase along the progression of CKD to maintain mineral homeostasis and to overcome end-organ resistance. It is hard to define when the increase of both hormones becomes maladaptive. CKD-MBD is associated with adverse outcomes including cardiovascular disease and mortality. This review summarizes the complex pathophysiology of CKD-MBD and outlines which laboratory abnormalities represent biomarkers of disease severity, which laboratory abnormalities are predictors of cardiovascular disease, and which laboratory abnormalities should be considered (direct) uremic toxins exerting organ damage. This information may help to streamline current and future therapeutic efforts.
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11
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Cozzolino M, Mehmeti F, Ciceri P, Volpi E, Stucchi A, Brenna I, Cusi D. The Effect of Paricalcitol on Vascular Calcification and Cardiovascular Disease in Uremia: Beyond PTH Control. Int J Nephrol 2011; 2011:269060. [PMID: 21603158 PMCID: PMC3096998 DOI: 10.4061/2011/269060] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2010] [Accepted: 01/18/2011] [Indexed: 01/08/2023] Open
Abstract
Secondary hyperparathyroidism is a systemic disorder that associates with bone and cardiovascular disease, including arterial calcification. Treatment with calcitriol, the active form of vitamin D, reduces parathyroid hormone levels, but may result in elevations in serum calcium and phosphorus, increasing the risk of vascular calcification in dialysis patients. New vitamin D receptor activators (VDRAs) have been developed and investigated with the rationale to treat high serum PTH levels, with a reduced risk of hypercalcemia and hyperphosphatemia. Paricalcitol is a selective VDRA that suppresses PTH secretion with minimal increases on serum calcium and phosphate. Moreover, paricalcitol prevents vascular calcification in experimental models of renal failure, compared with calcitriol.
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Affiliation(s)
- Mario Cozzolino
- Renal Division, DMCO, San Paolo Hospital, School of Medicine, University of Milan, Via A. di Rudinì 8; 20142, Milan, Italy
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Goto S, Fujii H, Hamada Y, Yoshiya K, Fukagawa M. Association Between Indoxyl Sulfate and Skeletal Resistance in Hemodialysis Patients. Ther Apher Dial 2010; 14:417-23. [DOI: 10.1111/j.1744-9987.2010.00813.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Sebastian EM, Suva LJ, Friedman PA. Differential effects of intermittent PTH(1-34) and PTH(7-34) on bone microarchitecture and aortic calcification in experimental renal failure. Bone 2008; 43:1022-30. [PMID: 18761112 PMCID: PMC2644420 DOI: 10.1016/j.bone.2008.07.250] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 07/18/2008] [Accepted: 07/24/2008] [Indexed: 01/01/2023]
Abstract
PTH(1-84) and PTH(7-84) are elevated in chronic kidney disease (CKD). These peptides, as their shorter analogs PTH(1-34) and PTH(7-34) both promote PTH receptor (PTH1R) internalization but only PTH(1-34) and PTH(1-84) activate the receptor. Here, we examined the effects of intermittent administration of PTH(1-34) and PTH(7-34) on mineral ion metabolism, bone architecture, and vascular calcification in rats with experimental CKD. CKD with or without parathyroidectomy (PTX) was established by 5/6 nephrectomy (NPX) in rats. Animals were divided into 4 groups: Sham PTX+ sham NPX (Sham); PTX+ sham NPX (PTX); Sham PTX+NPX (NPX); PTX+NPX (PTX/NPX). Rats were treated with single daily doses of 40 microg/kg PTH(1-34), PTH(7-34), or vehicle. Creatinine was higher in NPX and Ca lower in PTX and PTX/NPX groups than in Sham or NPX rats. Plasma phosphate was higher in PTX, NPX and PTX/NPX than in Sham rats. PTH(1-34) was more hypercalcemic than PTH(7-34) in PTX rats. Fractional bone volume in rats treated with PTH(1-34) increased significantly in all groups compared to that of vehicle treatment. In addition, trabecular number, thickness and volumetric bone density increased in rats treated with PTH(1-34). In contrast, PTH(1-34) diminished vascular calcification. Bone and renal PTH1R mRNA expression was reduced as much or more in PTX/NPX rats as in NPX alone, whereas PTH(7-34) had no effect on PTH1R expression. Renal but not bone PTH1R mRNA increased in response to PTH(1-34). These findings suggest that PTH(1-34) exerts greater hypercalcemic and anabolic effects in parathyroidectomized and/or nephrectomized rats than does PTH(7-34). There was no evidence for significant bone or vascular actions of PTH(7-34). We conclude that PTH(1-34) protects against vascular calcification and bone demineralization in experimental renal failure.
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Affiliation(s)
- Ely M. Sebastian
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Larry J. Suva
- Department of Orthopaedic Surgery, Center for Orthopaedic Research, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Peter A. Friedman
- Department of Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
- correspondence: Peter A. Friedman, Department of Pharmacology, University of Pittsburgh School of Medicine, W-1340 Biomedical Science Tower, Pittsburgh, PA 15261, USA., Tel: 412-383-7783, FAX: 412-648-1945, e-mail:
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Cozzolino M, Brancaccio D. Emerging role for the vitamin D receptor activator (VDRA), paricalcitol, in the treatment of secondary hyperparathyroidism. Expert Opin Pharmacother 2008; 9:947-54. [DOI: 10.1517/14656566.9.6.947] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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15
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Martin KJ, González EA. Pathophysiology of renal osteodystrophy. Clin Rev Bone Miner Metab 2007. [DOI: 10.1007/bf02736667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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16
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Spasovski G, Gelev S, Masin-Spasovska J, Selim G, Sikole A, Vanholder R. Improvement of bone and mineral parameters related to adynamic bone disease by diminishing dialysate calcium. Bone 2007; 41:698-703. [PMID: 17643363 DOI: 10.1016/j.bone.2007.06.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 05/24/2007] [Accepted: 06/20/2007] [Indexed: 11/26/2022]
Abstract
BACKGROUND The existence of adynamic bone disease (ABD) as most prevalent form of renal osteodystrophy in recent years and its reduced ability to handle an exogenous calcium load has implied a higher risk for vascular and soft-tissue calcifications. The effect of low dialysate calcium (LCD) on parathyroid hormone (PTH) secretion in ABD patients has not yet sufficiently been clarified. This randomized, prospective study aimed to compare the effects of LCD and high calcium dialysate (HCD) on the evolution of bone and mineral parameters related to ABD in dialysis patients. METHODS 52 out of 60 patients with predialysis intact PTH<100 pg/ml completed this study and were equally distributed over LCD (1.25 mmol/l) or HCD (1.75 mmol/l) treatment. The duration of the study was 6 months and the only peroral phosphate binder administered was calcium carbonate. Total and ionised calcium were measured monthly in serum before and after dialysis while serum parameters relevant to bone were measured at the enrollment and at 3-month intervals. RESULTS There were no differences in predialysis mean phosphate or calcium x phosphorus product (Ca x P). The most common side effects of both treatments were comparable. Hypotension occurred in 16% and 17% and cramps in 6% and 8% of the dialysis sessions, in the HCD and LCD group, respectively. The groups did not differ in the mean tCa before dialysis, but this parameter was significantly higher in the HCD group vs. LCD at the end of dialysis (2.59+/-0.18 vs. 2.44+/-0.19 mmol/l; p<0.01). The patients of the HCD group also had a significantly higher mean iCa both before (1.08+/-0.05 vs. 1.04+/-0.06 mmol/l; p=0.02) and at the end of dialysis (1.18+/-0.04 vs. 1.48+/-0.04 mmol/l; p<0.01). There were no differences within the LCD group between baseline and end of dialysis treatment values of tCa and iCa. However, the mean tCa and iCa were markedly increased at the end of dialysis in the HDC group [2.40+/-0.21 vs. 2.59+/-0.18 mmol/l (p<0.01); 1.08+/-0.05 vs. 1.18+/-0.04 mmol/l (p<0.01)]. Mean serum levels of iPTH and total alkaline phosphatase in the LCD group were increased at 3 months and at the end of the study compared with the baseline levels [(38.6+/-22.9 vs. 63.3+/-46.0 vs. 78.6+/-44.7 pg/ml); (59.5+/-18.7 vs. 75.9+/-26.7 vs. 84.0+/-35.4 U/l)], respectively, and bone alkaline phosphatase increased also only after 6 months of treatment (23.4+/-7.3 U/l vs. 35.6+/-22.3). The bone markers in the HCD group did not change. At the end of the study all bone parameters in the LCD group were significantly higher than in the HCD group. CONCLUSION There was an evolution towards parameters reflecting higher bone turnover in patients treated with dialysate calcium of 1.25 mmol/l, probably by prevention of a positive calcium balance and enabling sustained stimulation of PTH secretion. Hence, LCD might be considered a valuable therapeutic option for ABD patients.
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Affiliation(s)
- Goce Spasovski
- Department of Nephrology, Clinical Center Skopje, University of Skopje, Vodnjanska 17, 1000 Skopje, Macedonia.
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Spasovski GB. Bone health and vascular calcification relationships in chronic kidney disease. Int Urol Nephrol 2007; 39:1209-16. [PMID: 17899431 DOI: 10.1007/s11255-007-9276-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 08/13/2007] [Indexed: 10/22/2022]
Abstract
Abnormal bone in chronic kidney disease (CKD) may adversely affect vascular calcification via disordered calcium and phosphate metabolism. In this context, bone health should be viewed as a prerequisite for the successful prevention/treatment of vascular calcification (VC) along with controlled parathyroid hormone (PTH) secretion, the use of calcium-based phosphate binders and vitamin D therapy. In CKD patients, VC occurs more frequently and progresses more rapidly than in the general population, and is associated with increased cardiovascular disease (CVD) morbidity and mortality. A number of therapies aimed at reducing PTH concentration are associated with an increase of calcaemia and Ca x P product, e.g. calcium-containing phosphate binders or active vitamin D. The introduction of calcium-free phosphate binders has reduced calcium load, attenuating VC and improving trabecular bone content. In addition, a major breakthrough has been achieved through the use of calcimimetics, as first agents which lower PTH without increasing the concentrations of serum calcium and phosphate. Nowadays, it is becoming evident that even early stage CKD is recognised as an independent CVD risk factor. Moreover, the excess of CVD among dialysis patients cannot be explained entirely on the basis of abnormal mineral and bone metabolism. Hence, much controversy has surrounded the cost-effectiveness of treatment with the new phosphate-binding drugs as well as new vitamin D analogs and calcimimetics. Thus, it seems prudent and reasonable that maintaining bone health and mineral homeostasis should rely on some modifications of standard phosphate binding and calcitriol therapy. Hypophosphataemia and hypercalcaemia in adynamic bone disease (ABD) might be treated by reducing the number of calcium carbonate/acetate tablets in order to increase serum phosphate and decrease serum calcium, which, in turn, might positively stimulate PTH secretion. The same rationale is assumed for the use of a low calcium dialysate. On the other hand, secondary hyperparathyroidism with hyperphosphataemia and hypocalcaemia should be treated with a substantial number of calcium carbonate/acetate tablets in combination with calcitriol and low calcium dialysate in order to decrease serum phosphate and maintain the Ca x P product within K/DOQI guidelines (<4.4 mmol l(-1)). Finally, it becomes apparent that prevention, with judicious use of calcium-based binders, vitamin D and a low calcium dialysate without adverse effects on Ca x P or oversuppression of PTH, provides the best management of VC and mineral and bone disorder in CKD patients.
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Affiliation(s)
- Goce B Spasovski
- Department of Nephrology, University Clinical Center Skopje, Vodnjanska 17, Skopje, 1000, Macedonia.
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Hruska KA, Saab G, Mathew S, Lund R. PHOSPHORUS METABOLISM AND MANAGEMENT IN CHRONIC KIDNEY DISEASE: Renal Osteodystrophy, Phosphate Homeostasis, and Vascular Calcification. Semin Dial 2007; 20:309-15. [PMID: 17635820 DOI: 10.1111/j.1525-139x.2007.00300.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
New advances in the pathogenesis of renal osteodystrophy (ROD) change the perspective from which many of its features and treatment are viewed. Calcium, phosphate, parathyroid hormone (PTH), and vitamin D have been shown to be important determinants of survival associated with kidney diseases. Now ROD dependent and independent of these factors is linked to survival more than just skeletal frailty. This review focuses on recent discoveries that renal injury impairs skeletal anabolism decreasing the osteoblast compartment of the skeleton and consequent bone formation. This discovery and the discovery that PTH regulates the hematopoietic stem cell niche alters our view of secondary hyperparathyroidism in chronic kidney disease (CKD) from that of a disease to that of a necessary adaptation to renal injury that goes awry. Furthermore, ROD is shown to be an underappreciated factor in the level of the serum phosphorus in CKD. The discovery and the elucidation of the mechanism of hyperphosphatemia as a cardiovascular risk in CKD change the view of ROD. It is now recognized as more than a skeletal disorder, it is an important component of the mortality of CKD that can be treated.
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Affiliation(s)
- Keith A Hruska
- Renal Division, Departments of Pediatrics and Medicine, Washington University, St. Louis, Missouri 63110, USA.
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Neves KR, Graciolli FG, dos Reis LM, Graciolli RG, Neves CL, Magalhães AO, Custódio MR, Batista DG, Jorgetti V, Moysés RMA. Vascular calcification: contribution of parathyroid hormone in renal failure. Kidney Int 2007; 71:1262-70. [PMID: 17410101 DOI: 10.1038/sj.ki.5002241] [Citation(s) in RCA: 129] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Hyperphosphatemia is a driving force in the pathogenesis of vascular calcification (VC) and secondary hyperparathyroidism associated with renal failure. To test for the possible contribution of parathyroid hormone (PTH) to cardiovascular calcification, we removed the parathyroid glands from rats but infused synthetic hormone at a supraphysiologic rate. All rats were pair-fed low, normal, or high phosphorus diets and subjected to a sham or 5/6 nephrectomy (remnant kidney). Control rats were given a normal diet and underwent both sham parathyroidectomy and 5/6 nephrectomy. Heart weight/body weight ratios and serum creatinine levels were higher in remnant kidney rats than in the sham-operated rats. Remnant kidney rats on the high phosphorus diet and PTH replacement developed hyperphosphatemia and hypocalcemia along with low bone trabecular volume. Remnant kidney rats on the low phosphorus diet or intact kidney rats on a normal phosphorus diet, each with hormone replacement, developed hypercalcemia. All rats on PTH replacement developed intense aortic medial calcification, and some animals presented coronary calcification. We suggest that high PTH levels induce high bone turnover and medial calcification resembling Mömckeberg's sclerosis independent of uremia. This model may be useful in defining mechanisms underlying VC.
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Affiliation(s)
- K R Neves
- Department of Internal Medicine, Nephrology Division, University of São Paulo, São Paulo, SP, Brazil
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Kuwahara M, Inoshita S, Nakano Y, Terada Y, Takano Y, Sasaki S. Expression of bone type 1 PTH receptor in rats with chronic renal failure. Clin Exp Nephrol 2007; 11:34-40. [PMID: 17384996 DOI: 10.1007/s10157-006-0455-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2006] [Accepted: 12/19/2006] [Indexed: 10/23/2022]
Abstract
Some researchers have speculated that a decrease in bone type 1 PTH receptor (PTH1R) may be among the causes of "skeletal resistance" in chronic renal failure (CRF). Indeed, the down-regulation of PTH1R mRNA has been identified in uremic bones. However, few studies have identified the patterns of PTH1R protein expression. In this article we compare the bone expression of PTH1R protein and mRNA under control and CRF conditions. Sprague-Dawley rats underwent 5/6 nephrectomies (Nx) or sham operations (control), and were killed 16 weeks later. Blood urea nitrogen (BUN), serum Cr, P, and parathyroid hormone (PTH) were higher in the Nx group than in the controls, while serum Ca and 1,25(OH)(2)D(3) were lower in the Nx group. Immunohistochemical images of lumbar bone samples were analyzed by an image processing system. PTH1R was essentially identified in all osteoblasts. The expression of osteoblast PTH1R protein was quantified based on the gray value of PTH1R staining. The mean gray scale of osteoblasts was 25% lower in Nx rats than in control rats (P < 0.01), whereas osteoblast cell counts and cell sizes were not significantly different between the two groups. Thus, down-regulation of PTH1R protein expression under the CRF condition appeared likely. Total RNA extracted from the bone samples was reverse transcribed for real-time polymerase chain reaction (PCR). PTH1R mRNA expression was 33% lower in the Nx group than in the control group in the quantitative PCR analysis (P < 0.05). Our findings suggested that osteoblast PTH1R expression is down-regulated at both the protein and mRNA levels in the steady state of CRF.
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Affiliation(s)
- Michio Kuwahara
- Division of Nephrology, Shuwa General Hospital, 1200 Yahara-Shinden, Kasukabe, Saitama 344-0035, Japan.
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Nii-Kono T, Iwasaki Y, Uchida M, Fujieda A, Hosokawa A, Motojima M, Yamato H, Kurokawa K, Fukagawa M. Indoxyl sulfate induces skeletal resistance to parathyroid hormone in cultured osteoblastic cells. Kidney Int 2007; 71:738-43. [PMID: 17264878 DOI: 10.1038/sj.ki.5002097] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Skeletal resistance to parathyroid hormone (PTH) is well known to the phenomenon in chronic renal failure patient, but the detailed mechanism has not been elucidated. In the process of analyzing an animal model of renal failure with low bone turnover, we demonstrated decreased expression of PTH receptor (PTHR) accompanying renal dysfunction in this model. In the present study, we focused on the accumulation of uremic toxins (UTx) in blood, and examined whether indoxyl sulfate (IS), a UTx, is associated with PTH resistance. We established primary osteoblast cultures from mouse calvariae and cultured the cells in the presence of IS. The intracellular cyclic adenosine 3',5' monophosphate (cAMP) production, PTHR expression, and free radical production in the primary osteoblast culture were studied. We found that the addition of IS suppressed PTH-stimulated intracellular cAMP production and decreased PTHR expression in this culture system. Free radical production in osteoblasts increased depending on the concentration of IS added. Furthermore, expression of organic anion transporter-3 (OAT-3) that is known to mediate cellular uptake of IS was identified in the primary osteoblast culture. These results suggest that IS taken up by osteoblasts via OAT-3 present in these cells augments oxidative stress to impair osteoblast function and downregulate PTHR expression. These finding strongly suggest that IS accumulated in blood due to renal dysfunction is at least one of the factors that induce skeletal resistance to PTH.
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Affiliation(s)
- T Nii-Kono
- Division of Nephrology and Dialysis Center, Department of Internal Medicine, Kobe University School of Medicine, Kobe, Japan
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Iwasaki Y, Yamato H, Nii-Kono T, Fujieda A, Uchida M, Hosokawa A, Motojima M, Fukagawa M. Administration of oral charcoal adsorbent (AST-120) suppresses low-turnover bone progression in uraemic rats. Nephrol Dial Transplant 2006; 21:2768-74. [PMID: 16820376 DOI: 10.1093/ndt/gfl311] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Using a rat model of renal failure with normal parathyroid hormone levels, we had demonstrated previously that bone formation decreased depending on the degree of renal dysfunction, and hypothesized that uraemic toxins (UTx) are associated with the development of low-turnover bone development, complicating renal failure. In this study, focusing on indoxyl sulphate (IS) as a representative UTx, we analysed the effect of an oral charcoal adsorbent AST-120, which removes uraemic toxins and their precursors from the gastrointestinal tract, on bone turnover. METHODS AST-120 or vehicle was administered orally to model rats with uraemia and low turnover bone. Bone turnover was analysed by histomorphometry. Expression of osteoblast-related genes and oat-3 gene was analysed by reverse transcription polymerase chain reaction. RESULTS In rats treated with vehicle, serum IS level increased with time after renal dysfunction, while bone formation decreased accompanied by down-regulation of the parathyroid/parathyroid-related peptide hormone receptor, alkaline phosphatase and osteocalcin genes. Administration of AST-120 inhibited the accumulation of IS in blood and ameliorated bone formation. Bone formation rate was 2.4 +/- 1.7 microm(3)/m(2)/year in controls given vehicle and was 11.7 +/- 2.4 microm(3)/m(2)/year in rats administered with AST-120 (P < 0.05). AST-120 treatment also reversed the down-regulation of osteoblast-related genes. Gene expression of oat-3 was detected in the tibia of rats. CONCLUSION Administration of the oral charcoal adsorbent AST-120 decreases the osteoblast cytotoxicity of UTx including IS, and suppresses progression of low bone turnover in uraemic rats.
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Affiliation(s)
- Yoshiko Iwasaki
- Department of Health Sciences, Oiya University of Nursing and Health Sciences, Oita 870-1201, Japan
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Iwasaki Y, Yamato H, Nii-Kono T, Fujieda A, Uchida M, Hosokawa A, Motojima M, Fukagawa M. Insufficiency of PTH action on bone in uremia. Kidney Int 2006:S34-6. [PMID: 16810309 DOI: 10.1038/sj.ki.5001600] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Abnormal bone turnover and mineral metabolism is observed in patients on dialysis. Secondary hyperparathyroidism (SHP) develops in response to mineral metabolism changes accompanying renal failure. As a factor of disease progression, the phenomenon of skeletal resistance to parathyroid hormone (PTH) is observed. With recent advances in the treatment of SHP, over-secretion of PTH can now be controlled. However, blood PTH levels 2 to 3 times higher than normal are considered necessary to maintain normal bone turnover in patients with renal failure. Various causes of skeletal resistance to PTH have been reported, including decrease in PTH receptor in osteoblasts, accumulation of 7-84 PTH fragment, and accumulation of osteoprotegerin. This skeletal resistance to PTH is not only a high-turnover bone accompanying SHP, but may also play a crucial role in the onset of low-turnover bone disease. We have produced a rat model of renal failure with normal level of PTH secretion and analyzed the bone of this model. Our results confirmed that bone turnover is lowered accompanying renal function impairment. We also found that this lowered bone turnover is improved by intermittent administration of PTH. In addition, PTH receptor gene expression is also decreased in low-turnover bone, as is observed in high-turnover bone disease. These findings confirm the presence of skeletal resistance to PTH in low-turnover bone accompanying renal failure. Control of calcium, phosphorus, and PTH levels with the target to maintain normal bone turnover is important in maintaining the quality of life of patients on dialysis.
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Affiliation(s)
- Y Iwasaki
- Department of Health Sciences, Oita University of Nursing and Health Sciences, Oita, Japan.
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Abstract
This review considers many new basic and clinical aspects of parathyroid hormone (PTH). We focus especially on the identification of PTH fragments and how they may relate to renal failure, diagnosis, and treatment of secondary hyperparathyroidism and renal osteodystrophy. The biosynthesis and metabolism of PTH, measurement of circulating forms of PTH, the effects of PTH on receptor activation and turnover, the relationship between PTH levels and bone turnover in renal failure in humans, and the involvement of PTH in experimental models of renal failure are discussed. Despite these developments in understanding the etiology of renal failure and the availability of new assays for bioactive PTH, no adequate surrogate for bone biopsy and quantitative bone histomorphometry has been developed.
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Affiliation(s)
- Peter A Friedman
- Univ. of Pittsburgh School of Medicine, Dept. of Pharmacology, E-1347 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
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Iwasaki Y, Yamato H, Nii-Kono T, Fujieda A, Uchida M, Hosokawa A, Motojima M, Fukagawa M. Uremic toxin and bone metabolism. J Bone Miner Metab 2006; 24:172-5. [PMID: 16502128 DOI: 10.1007/s00774-005-0667-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Accepted: 09/02/2005] [Indexed: 11/29/2022]
Abstract
Patients with end-stage renal disease (ESRD) develop various kinds of abnormalities in bone and mineral metabolism, widely known as renal osteodystrophy (ROD). Although the pathogenesis of ESRD may be similar in many patients, the response of the bone varies widely, ranging from high to low turnover. ROD is classified into several types, depending on the status of bone turnover, by histomorphometric analysis using bone biopsy samples [1,2]. In the mild type, bone metabolism is closest to that of persons with normal renal function. In osteitis fibrosa, bone turnover is abnormally activated. This is a condition of high-turnover bone. A portion of the calcified bone loses its lamellar structure and appears as woven bone. In the cortical bone also, bone resorption by osteoclasts is active, and a general picture of bone marrow tissue infiltration and the formation of cancellous bone can be observed. In osteomalacia, the bone surface is covered with uncalcified osteoid. This condition is induced by aluminum accumulation or vitamin D deficiency. The mixed type possesses characteristics of both osteitis fibrosa and osteomalacia. The bone turnover is so markedly accelerated that calcification of the osteoid cannot keep pace. In the adynamic bone type, bone resorption and bone formation are both lowered. While bone turnover is decreased, there is little osteoid. The existence of these various types probably accounts for the diversity in degree of renal impairment, serum parathyroid hormone (PTH) level, and serum vitamin D level in patients with ROD. However, all patients share a common factor, i.e., the presence of a uremic condition.
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Affiliation(s)
- Yoshiko Iwasaki
- Department of Health Sciences, Oita University of Nursing and Health Sciences, 2944-9 Megusuno, Oita, 870-1201, Japan
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Iwasaki-Ishizuka Y, Yamato H, Nii-Kono T, Kurokawa K, Fukagawa M. Downregulation of parathyroid hormone receptor gene expression and osteoblastic dysfunction associated with skeletal resistance to parathyroid hormone in a rat model of renal failure with low turnover bone. Nephrol Dial Transplant 2005; 20:1904-11. [PMID: 15985520 DOI: 10.1093/ndt/gfh876] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Adynamic bone disease (ABD), which is characterized by reduced bone formation and resorption, has become an increasingly common manifestation of bone abnormalities in patients with end-stage renal failure. It has been recognized that skeletal resistance to parathyroid hormone (PTH) underlies the pathogenesis of ABD; however, the mechanisms of such resistance remain unclear. METHODS We established a rat model simulating ABD under chronic renal failure conditions by thyroparathyroidectomy and partial nephrectomy (TPTx-Nx). TPTx-Nx rats were infused subcutaneously with a physiological dose of PTH. We analysed bone histomorphometric parameters and demonstrated gene expression using semi-quantitative reverse transcription-polymerase chain reaction. RESULTS Reduced bone formation was observed in this model, simulating ABD. The reduction was dependent on the degree of renal dysfunction. Bone formation rate was 6.4+/-2.7 microm3/m2/year in TPTx-5/6Nx rats and 22.7+/-7.2 microm3/m2/year in TPTx rats (P<0.05). Osteoblast surface was also significantly depressed (P<0.05) in TPTx-5/6Nx (3.8+/-2.7%) compared with TPTx rats (15.9+/-8.6). The expression of PTH/parathyroid hormone-related peptide (PTHrP) receptor and alkaline phosphatase genes was reduced significantly in TPTx-Nx compared with TPTx rats (P<0.05). Reduced bone formation in TPTx-Nx rats was ameliorated by intermittent injection of pharmacological doses of PTH. CONCLUSIONS Renal dysfunction without secondary hyperparathyroidism induces osteoblast dysfunction and reduces bone formation. Skeletal resistance to PTH develops in renal failure even at low or normal PTH levels, possibly through downregulation of PTH/PTHrP receptor and dysfunction of osteoblasts.
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Affiliation(s)
- Yoshiko Iwasaki-Ishizuka
- Department of Health Sciences, Oita University of Nursing and Health Sciences, Oita, 870-1201, Japan
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