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Wilson R, Mukherjee-Roy N, Gattineni J. The role of fibroblast growth factor 23 in regulation of phosphate balance. Pediatr Nephrol 2024:10.1007/s00467-024-06395-5. [PMID: 38874635 DOI: 10.1007/s00467-024-06395-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 04/22/2024] [Accepted: 04/22/2024] [Indexed: 06/15/2024]
Abstract
Phosphate is essential for numerous biological processes, and serum levels are tightly regulated to accomplish these functions. The regulation of serum phosphate in a narrow physiological range is a well-orchestrated process and involves the gastrointestinal (GI) tract, bone, kidneys, and several hormones, namely, parathyroid hormone, fibroblast growth factor 23 (FGF23), and 1,25-dihydroxyvitamin D (1,25 Vitamin D). Although primarily synthesized in the bone, FGF23, an endocrine FGF, acts on the kidney to regulate phosphate and Vitamin D homeostasis by causing phosphaturia and reduced levels of 1,25 Vitamin D. Recent studies have highlighted the complex regulation of FGF23 including transcriptional and post-translational modification and kidney-bone cross talk. Understanding FGF23 biology has led to the identification of novel therapeutic agents to treat diseases that disrupt phosphate metabolism secondary to FGF23. The focus of this review is to provide an overview of phosphate homeostasis, FGF23 biology, and the role of FGF23 in phosphate balance.
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Affiliation(s)
| | - Neije Mukherjee-Roy
- Division of Pediatric Nephrology, Department of Pediatrics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, USA
| | - Jyothsna Gattineni
- Division of Pediatric Nephrology, Department of Pediatrics, The University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, USA.
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2
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Fukumoto S. Tumor-induced osteomalacia. Panminerva Med 2024; 66:188-197. [PMID: 38127062 DOI: 10.23736/s0031-0808.23.05047-4] [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: 12/23/2023]
Abstract
Tumor-induced osteomalacia is one of paraneoplastic syndromes characterized by hypophosphatemia caused by excessive actions of fibroblast growth factor 23 (FGF23). Since the cloning of FGF23 about 20 years ago, more widespread awareness of this disease has been achieved. However, there still remain several difficulties in the management of patients with this disease. In this review, these clinical problems are discussed together with the physiological and pathophysiological functions of FGF23. Personal proposals in the management of patients with suspected patients with tumor-induced osteomalacia are also presented.
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Affiliation(s)
- Seiji Fukumoto
- Department of Diabetes and Endocrinology, Tamaki-Aozora Hospital, Tokushima, Japan -
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3
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Martínez-Heredia L, Canelo-Moreno JM, García-Fontana B, Muñoz-Torres M. Non-Classical Effects of FGF23: Molecular and Clinical Features. Int J Mol Sci 2024; 25:4875. [PMID: 38732094 PMCID: PMC11084844 DOI: 10.3390/ijms25094875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 04/21/2024] [Accepted: 04/26/2024] [Indexed: 05/13/2024] Open
Abstract
This article reviews the role of fibroblast growth factor 23 (FGF23) protein in phosphate metabolism, highlighting its regulation of vitamin D, parathyroid hormone, and bone metabolism. Although it was traditionally thought that phosphate-calcium homeostasis was controlled exclusively by parathyroid hormone (PTH) and calcitriol, pathophysiological studies revealed the influence of FGF23. This protein, expressed mainly in bone, inhibits the renal reabsorption of phosphate and calcitriol formation, mediated by the α-klotho co-receptor. In addition to its role in phosphate metabolism, FGF23 exhibits pleiotropic effects in non-renal systems such as the cardiovascular, immune, and metabolic systems, including the regulation of gene expression and cardiac fibrosis. Although it has been proposed as a biomarker and therapeutic target, the inhibition of FGF23 poses challenges due to its potential side effects. However, the approval of drugs such as burosumab represents a milestone in the treatment of FGF23-related diseases.
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Affiliation(s)
- Luis Martínez-Heredia
- Instituto de Investigación Biosanitaria de Granada, 18014 Granada, Spain;
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | | | - Beatriz García-Fontana
- Instituto de Investigación Biosanitaria de Granada, 18014 Granada, Spain;
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, 18016 Granada, Spain
- Department of Cell Biology, University of Granada, 18016 Granada, Spain
| | - Manuel Muñoz-Torres
- Instituto de Investigación Biosanitaria de Granada, 18014 Granada, Spain;
- Biomedical Research Network in Fragility and Healthy Aging (CIBERFES), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Endocrinology and Nutrition Unit, University Hospital Clínico San Cecilio, 18016 Granada, Spain
- Department of Medicine, University of Granada, 18016 Granada, Spain
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4
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Fukumoto S. Regulation of FGF23 Production in Osteocytes. Curr Osteoporos Rep 2024; 22:273-279. [PMID: 38334918 DOI: 10.1007/s11914-024-00860-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 02/10/2024]
Abstract
PURPOSE OF REVIEW FGF23 is a bone-derived hormone working to reduce serum phosphate level. This review focuses on recent findings regarding regulatory mechanisms of FGF23 expression in osteocytes, FGF23 levels, and activities. RECENT FINDINGS Circulatory FGF23 levels reflecting FGF23 biological activities can be regulated by both FGF23 expression and posttranslational modification of FGF23 protein. O-linked glycosylation and phosphorylation of FGF23 protein as well as enzymes that can cleave FGF23 protein are involved in the posttranslational modification. However, precise mechanisms of FGF23 protein processing are not clear. Several extracellular factors have been shown to affect FGF23 levels in kidney injuries. Contribution of these factors may be different depending on the causes and stages of kidney injury. FGF23 activities are regulated by complex mechanisms involving transcriptional and posttranslational modulations. There still remain several questions regarding the regulatory mechanisms of FGF23 expression and FGF23 processing.
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Affiliation(s)
- Seiji Fukumoto
- Department of Diabetes and Endocrinology, Tamaki-Aozora Hospital, Kitakashiya 56-1, Hayabuchi, Kokufucho, Tokushima, Tokushima, 779-3125, Japan.
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Ay B, Cyr SM, Klovdahl K, Zhou W, Tognoni CM, Iwasaki Y, Rhee EP, Dedeoglu A, Simic P, Bastepe M. Gα11 deficiency increases fibroblast growth factor 23 levels in a mouse model of familial hypocalciuric hypercalcemia. JCI Insight 2024; 9:e178993. [PMID: 38530370 PMCID: PMC11141917 DOI: 10.1172/jci.insight.178993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 03/14/2024] [Indexed: 03/28/2024] Open
Abstract
Fibroblast growth factor 23 (FGF23) production has recently been shown to increase downstream of Gαq/11-PKC signaling in osteocytes. Inactivating mutations in the gene encoding Gα11 (GNA11) cause familial hypocalciuric hypercalcemia (FHH) due to impaired calcium-sensing receptor signaling. We explored the effect of Gα11 deficiency on FGF23 production in mice with heterozygous (Gna11+/-) or homozygous (Gna11-/-) ablation of Gna11. Both Gna11+/- and Gna11-/- mice demonstrated hypercalcemia and mildly raised parathyroid hormone levels, consistent with FHH. Strikingly, these mice also displayed increased serum levels of total and intact FGF23 and hypophosphatemia. Gna11-/- mice showed augmented Fgf23 mRNA levels in the liver and heart, but not in bone or bone marrow, and also showed evidence of systemic inflammation with elevated serum IL-1β levels. Furin gene expression was significantly increased in the Gna11-/- liver, suggesting enhanced FGF23 cleavage despite the observed rise in circulating intact FGF23 levels. Gna11-/- mice had normal renal function and reduced serum levels of glycerol-3-phosphate, excluding kidney injury as the primary cause of elevated intact FGF23 levels. Thus, Gα11 ablation caused systemic inflammation and excess serum FGF23 in mice, suggesting that patients with FHH - at least those with GNA11 mutations - may be at risk for these complications.
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Affiliation(s)
- Birol Ay
- Endocrine Unit, Department of Medicine, and
| | | | | | - Wen Zhou
- Endocrine Unit, Department of Medicine, and
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Christina M. Tognoni
- Department of Veterans Affairs, VA Boston Healthcare System, Boston, Massachusetts, USA
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, USA
| | | | - Eugene P Rhee
- Endocrine Unit, Department of Medicine, and
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Alpaslan Dedeoglu
- Department of Veterans Affairs, VA Boston Healthcare System, Boston, Massachusetts, USA
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, USA
- Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Massachusetts, USA
| | - Petra Simic
- Endocrine Unit, Department of Medicine, and
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
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6
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Hamid AK, Pastor Arroyo EM, Calvet C, Hewitson TD, Muscalu ML, Schnitzbauer U, Smith ER, Wagner CA, Egli-Spichtig D. Phosphate Restriction Prevents Metabolic Acidosis and Curbs Rise in FGF23 and Mortality in Murine Folic Acid-Induced AKI. J Am Soc Nephrol 2024; 35:261-280. [PMID: 38189228 PMCID: PMC10914210 DOI: 10.1681/asn.0000000000000291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 12/02/2023] [Indexed: 01/09/2024] Open
Abstract
SIGNIFICANCE STATEMENT Patients with AKI suffer a staggering mortality rate of approximately 30%. Fibroblast growth factor 23 (FGF23) and phosphate (P i ) rise rapidly after the onset of AKI and have both been independently associated with ensuing morbidity and mortality. This study demonstrates that dietary P i restriction markedly diminished the early rise in plasma FGF23 and prevented the rise in plasma P i , parathyroid hormone, and calcitriol in mice with folic acid-induced AKI (FA-AKI). Furthermore, the study provides evidence for P i -sensitive osseous Fgf23 mRNA expression and reveals that P i restriction mitigated calciprotein particles (CPPs) formation, inflammation, acidosis, cardiac electrical disturbances, and mortality in mice with FA-AKI. These findings suggest that P i restriction may have a prophylactic potential in patients at risk for AKI. BACKGROUND In AKI, plasma FGF23 and P i rise rapidly and are independently associated with disease severity and outcome. METHODS The effects of normal (NP) and low (LP) dietary P i were investigated in mice with FA-AKI after 3, 24, and 48 hours and 14 days. RESULTS After 24 hours of AKI, the LP diet curbed the rise in plasma FGF23 and prevented that of parathyroid hormone and calcitriol as well as of osseous but not splenic or thymic Fgf23 mRNA expression. The absence of Pth prevented the rise in calcitriol and reduced the elevation of FGF23 in FA-AKI with the NP diet. Furthermore, the LP diet attenuated the rise in renal and plasma IL-6 and mitigated the decline in renal α -Klotho. After 48 hours, the LP diet further dampened renal IL-6 expression and resulted in lower urinary neutrophil gelatinase-associated lipocalin. In addition, the LP diet prevented the increased formation of CPPs. Fourteen days after AKI induction, the LP diet group maintained less elevated plasma FGF23 levels and had greater survival than the NP diet group. This was associated with prevention of metabolic acidosis, hypocalcemia, hyperkalemia, and cardiac electrical disturbances. CONCLUSIONS This study reveals P i -sensitive FGF23 expression in the bone but not in the thymus or spleen in FA-AKI and demonstrates that P i restriction mitigates CPP formation, inflammation, acidosis, and mortality in this model. These results suggest that dietary P i restriction could have prophylactic potential in patients at risk for AKI.
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Affiliation(s)
- Ahmad Kamal Hamid
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| | - Eva Maria Pastor Arroyo
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| | - Charlotte Calvet
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Zurich Integrative Rodent Physiology (ZIRP), University of Zurich, Zurich, Switzerland
| | - Timothy D. Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Australia
- Department of Medicine, University of Melbourne, Melbourne Australia
| | - Maria Lavinia Muscalu
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| | - Udo Schnitzbauer
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Edward R. Smith
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Australia
- Department of Medicine, University of Melbourne, Melbourne Australia
| | - Carsten Alexander Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
| | - Daniela Egli-Spichtig
- Institute of Physiology, University of Zurich, Zurich, Switzerland
- Swiss National Centre of Competence in Research (NCCR) Kidney.CH, Zurich, Switzerland
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Hidaka N, Inoue K, Kato H, Hoshino Y, Koga M, Kinoshita Y, Takashi Y, Makita N, Fukumoto S, Nangaku M, Ito N. FGF-23, Left Ventricular Hypertrophy, and Mortality in Patients With CKD: A Revisit With Mediation Analysis. JACC. ADVANCES 2024; 3:100747. [PMID: 38939808 PMCID: PMC11198284 DOI: 10.1016/j.jacadv.2023.100747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 10/05/2023] [Accepted: 10/30/2023] [Indexed: 06/29/2024]
Abstract
Background In patients with chronic kidney disease (CKD), fibroblast growth factor (FGF)-23 is suspected to cause death or cardiovascular disease by inducing left ventricular hypertrophy (LVH). Objectives This study aims to quantify the mediational effect of LVH in the hypothetical causal pathway from FGF-23 to long-term adverse outcomes. Methods From 3,939 adults with CKD stages 2 to 4 enrolled in the CRIC (Chronic Renal Insufficiency Cohort) study, 2,368 participants with available data of FGF-23, left ventricular mass index at 1 year, and covariates were included. We employed linear and Cox proportional hazards regression models to investigate the association between FGF-23 and LVH, all-cause mortality, atrial fibrillation (AF), or congestive heart failure (CHF). Mediation analysis was used within a counterfactual framework to decompose the effect of FGF-23 into natural direct and indirect effects. Results Among 2,368 participants (mean age: 57.7 years, 1,252 males, median FGF-23 level: 138.8 RU/mL), left ventricular mass index was positively correlated with FGF-23. During a median of 12.0, 11.1, and 11.1 years, FGF-23 was associated with all-cause mortality (HR: 1.62, 95% CI: 1.24-2.12), AF (HR: 1.58, 95% CI: 1.12-2.24), and CHF (HR: 1.32, 95% CI: 0.95-1.84) when the highest quartile was compared to the lowest quartile. LVH mediated 7.4%, 11.2%, and 21.9% of the effect of FGF-23 on all-cause mortality, AF, and CHF, respectively. Conclusions In CKD patients, FGF-23 had a minor effect on the development of long-term adverse outcomes through LVH. Other potential mediators and the validity of negative effect of FGF-23 should be explored.
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Affiliation(s)
- Naoko Hidaka
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
- Osteoporosis Center, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
| | - Kosuke Inoue
- Department of Social Epidemiology, Graduate School of Medicine, Kyoto University, Sakyo, Kyoto, Japan
| | - Hajime Kato
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
- Osteoporosis Center, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
| | - Yoshitomo Hoshino
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
- Osteoporosis Center, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
| | - Minae Koga
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
- Osteoporosis Center, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
| | - Yuka Kinoshita
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
- Osteoporosis Center, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
| | - Yuichi Takashi
- Department of Endocrinology and Diabetes Mellitus, Fukuoka University School of Medicine, Jonan, Fukuoka, Japan
| | - Noriko Makita
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
- Osteoporosis Center, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
| | - Seiji Fukumoto
- Fujii Memorial Institute of Medical Sciences, Institute of Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
| | - Nobuaki Ito
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
- Osteoporosis Center, The University of Tokyo Hospital, Bunkyo, Tokyo, Japan
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8
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Xiao L, Clarke K, Hurley MM. Fibroblast Growth Factor 23 Neutralizing Antibody Ameliorates Abnormal Renal Phosphate Handling in Sickle Cell Disease Mice. Endocrinology 2023; 164:bqad173. [PMID: 37972265 PMCID: PMC11032245 DOI: 10.1210/endocr/bqad173] [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: 09/06/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
We assessed the involvement of fibroblast growth factor 23 (FGF23) in phosphaturia in sickle cell disease (SCD) mice. Control and SCD mice were treated with FGF23 neutralizing antibody (FGF23Ab) for 24 hours. Serum ferritin was significantly increased in SCD mice and was significantly reduced in female but not male SCD mice by FGF23Ab. FGF23Ab significantly reduced increased erythropoietin in SCD kidneys. Serum intact FGF23 was significantly increased in SCD female mice and was markedly increased in SCD male mice; however, FGF23Ab significantly reduced serum intact FGF23 in both genotypes and sexes. Serum carboxy-terminal-fragment FGF23 (cFGF23) was significantly reduced in SCD IgG male mice and was markedly but not significantly reduced in SCD IgG female mice. FGF23Ab significantly increased cFGF23 in both sexes and genotypes. Serum 1,25-dihydroxyvitamin D3 was significantly increased in SCD IgG and was further significantly increased by FGF23Ab in both sexes and genotypes. Significantly increased blood urea nitrogen in SCD was not reduced by FGF23Ab. The urine phosphate (Pi)/creatinine ratio was significantly increased in SCD in both sexes and was significantly reduced by FGF23Ab. Increased SCD kidney damage marker kidney injury molecule 1 was rescued, but sclerotic glomeruli, increased macrophages, and lymphocytes were not rescued by short-term FGF23Ab. FGF23Ab significantly reduced increased phospho-fibroblast growth factor receptor 1, αKlotho, phosphorylated extracellular signal-regulated kinase, phosphorylated serum/glucocorticoid-regulated kinase 1, phosphorylated sodium-hydrogen exchanger regulatory factor-1, phosphorylated janus kinase 3, and phosphorylated transducer and activator of transcription-3 in SCD kidneys. The type II sodium Pi cotransporter (NPT2a) and sodium-dependent Pi transporter PiT-2 proteins were significantly reduced in SCD kidneys and were increased by FGF23Ab. We conclude that increased FGF23/FGF receptor 1/αKlotho signaling promotes Pi wasting in SCD by downregulating NPT2a and PIT2 via modulation of multiple signaling pathways that could be rescued by FGF23Ab.
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Affiliation(s)
- Liping Xiao
- Department of Medicine, Division of Endocrinology and Metabolism, UConn Health School of Medicine, Farmington, CT, 06030, USA
| | - Kai Clarke
- Department of Medicine, Division of Endocrinology and Metabolism, UConn Health School of Medicine, Farmington, CT, 06030, USA
| | - Marja M Hurley
- Department of Medicine, Division of Endocrinology and Metabolism, UConn Health School of Medicine, Farmington, CT, 06030, USA
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Grimbly C, Ludwig K, Wu Z, Caluseriu O, Rosolowsky E, Alexander RT, Ward LM, Rauch F. X-linked hypophosphatemia caused by a deep intronic variant in PHEX identified by PCR-based RNA analysis of urine-derived cells. Bone 2023; 176:116839. [PMID: 37454963 DOI: 10.1016/j.bone.2023.116839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/28/2023] [Accepted: 07/12/2023] [Indexed: 07/18/2023]
Abstract
X-linked hypophosphatemia (XLH) is caused by dominant inactivating mutations in the phosphate regulating endopeptidase homology, X-linked (PHEX), resulting in elevated fibroblast growth factor 23 (FGF23), hypophosphatemia, rickets and osteomalacia. PHEX variants are identified in approximately 85 % of individuals with XLH, which leaves a substantial proportion of patients with negative DNA-based genetic testing. Here we describe a 16-year-old male who had typical features of XLH on clinical and radiological examination. Genomic DNA sequencing of a hypophosphatemia gene panel did not reveal a pathogenic variant. We therefore obtained a urine sample, established cell cultures and obtained PHEX cDNA from urine-derived cells. Sequencing of exon-spanning PCR products demonstrated the presence of an 84 bp pseudoexon in PHEX intron 21 due to a deep intronic variant (c.2147+1197A>G), which created a new splice donor site in intron 21. The corresponding PHEX protein would lack 33 amino acids on the C-terminus and instead include an unrelated sequence of 17 amino acids. The patient and his affected mother both had this variant. This report highlights that individuals with the typical clinical characteristics of XLH and negative genomic DNA sequence analysis can have deep intronic PHEX variants that are detectable by PCR-based RNA diagnostics.
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Affiliation(s)
- Chelsey Grimbly
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada; Women and Children's Health Research Institute, Edmonton, AB, Canada.
| | - Karissa Ludwig
- Shriners Hospital for Children - Canada, Montreal, QC, Canada
| | - Zenghui Wu
- Shriners Hospital for Children - Canada, Montreal, QC, Canada
| | - Oana Caluseriu
- Women and Children's Health Research Institute, Edmonton, AB, Canada; Department of Genetics, University of Alberta, Edmonton, AB, Canada
| | - Elizabeth Rosolowsky
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada; Women and Children's Health Research Institute, Edmonton, AB, Canada
| | - R Todd Alexander
- Department of Pediatrics, University of Alberta, Edmonton, AB, Canada; Women and Children's Health Research Institute, Edmonton, AB, Canada
| | - Leanne M Ward
- Department of Pediatrics, University of Ottawa, Division of Endocrinology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Frank Rauch
- Shriners Hospital for Children - Canada, Montreal, QC, Canada
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10
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Bosman A, Ratsma DMA, van der Eerden BCJ, Zillikens MC. Case Report: Unexplained Mild Hypophosphatemia and Very High Serum FGF23 Concentrations. JBMR Plus 2023; 7:e10790. [PMID: 37808399 PMCID: PMC10556273 DOI: 10.1002/jbm4.10790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 06/07/2023] [Accepted: 06/10/2023] [Indexed: 10/10/2023] Open
Abstract
Fibroblast growth factor (FGF)23 is one of the major regulators of phosphate homeostasis. Hypophosphatemia can lead to muscle weakness, fatigue, and osteomalacia. In the setting of hypophosphatemia, serum FGF23 can be measured to differentiate between FGF23-mediated and non-FGF23-mediated renal phosphate wasting. C-terminal FGF23 (cFGF23) assays detect both cFGF23 and intact FGF23 (iFGF23). Circulating FGF23 is regulated by 1.25-dihydroxy-vitamin D, parathyroid hormone (PTH), serum phosphate, and serum calcium but also by, for example, iron status, inflammation, erythropoietin, and hypoxia-inducible-factor-1-α. We present the case of a 48-year-old woman with unexplained mild hypophosphatemia, very high cFGF23, and normal iFGF23. The patient proved to have an iron deficiency. Iron deficiency alters the iFGF23-to-cFGF23 ratio. After initiation of iron treatment, cFGF23 strongly decreased. This case report illustrates the limitation of cFGF23 assays and urges clinicians to be aware that cFGF23 concentrations do not necessarily reflect iFGF23 concentrations and that alternative causes for its elevation should be considered (eg, iron deficiency). © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Ariadne Bosman
- Department of Internal MedicineErasmus MC, University Medical CenterRotterdamThe Netherlands
| | - Danielle MA Ratsma
- Department of Internal MedicineErasmus MC, University Medical CenterRotterdamThe Netherlands
| | - Bram CJ van der Eerden
- Department of Internal MedicineErasmus MC, University Medical CenterRotterdamThe Netherlands
| | - M Carola Zillikens
- Department of Internal MedicineErasmus MC, University Medical CenterRotterdamThe Netherlands
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11
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Magagnoli L, Cozzolino M, Galassi A. The open system of FGF-23 at the crossroad between additional P-lowering therapy, anemia and inflammation: how to deal with the intact and the C-terminal assays? Clin Kidney J 2023; 16:1543-1549. [PMID: 37779858 PMCID: PMC10539210 DOI: 10.1093/ckj/sfad144] [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: 04/18/2023] [Indexed: 10/03/2023] Open
Abstract
Fibroblast growth factor 23 (FGF-23) has been associated with increased cardiovascular risk and poor survival in dialysis patients. It is well established that FGF-23 synthesis is directly induced by positive phosphate (P) balance. On the other hand, P-lowering treatments such as nutritional P restriction, P binders and dialysis are capable of reducing FGF-23 levels. However, there are many uncertainties regarding the possibility of adopting FGF-23 to guide the clinical decision-making process in the context of chronic kidney disease-mineral bone disorder (CKD-MBD). Furthermore, the best assay to adopt for measurement of FGF-23 levels (namely the intact vs the C-terminal one) remains to be determined, especially in conditions capable of altering the synthesis as well as the cleavage of the intact and biologically active molecule, as occurs in the presence of CKD and its complications. This Editorial discusses the main insights provided by the post hoc analysis of the NOPHOS trial, with particular attention given to evidence-based peculiarities of the intact and the C-terminal assays available for measuring FGF-23 levels, especially in patients receiving additive P-lowering therapy in the presence of inflammation, anemia and iron deficiency.
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Affiliation(s)
- Lorenza Magagnoli
- University of Milan, Department of Health Sciences, Milano, Italy
- ASST Santi Paolo e Carlo, Renal Division, Milano, Italy
| | - Mario Cozzolino
- University of Milan, Department of Health Sciences, Milano, Italy
- ASST Santi Paolo e Carlo, Renal Division, Milano, Italy
| | - Andrea Galassi
- University of Milan, Department of Health Sciences, Milano, Italy
- ASST Santi Paolo e Carlo, Renal Division, Milano, Italy
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Li X, Lozovatsky L, Tommasini SM, Fretz J, Finberg KE. Bone marrow sinusoidal endothelial cells are a site of Fgf23 upregulation in a mouse model of iron deficiency anemia. Blood Adv 2023; 7:5156-5171. [PMID: 37417950 PMCID: PMC10480544 DOI: 10.1182/bloodadvances.2022009524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 06/16/2023] [Accepted: 07/05/2023] [Indexed: 07/08/2023] Open
Abstract
Iron deficiency is a potent stimulator of fibroblast growth factor 23 (FGF23), a hormonal regulator of phosphate and vitamin D metabolism, that is classically thought to be produced by bone-embedded osteocytes. Here, we show that iron-deficient transmembrane serine protease 6 knockout (Tmprss6-/-) mice exhibit elevated circulating FGF23 and Fgf23 messenger RNA (mRNA) upregulation in the bone marrow (BM) but not the cortical bone. To clarify sites of Fgf23 promoter activity in Tmprss6-/- mice, we introduced a heterozygous enhanced green fluorescent protein (eGFP) reporter allele at the endogenous Fgf23 locus. Heterozygous Fgf23 disruption did not alter the severity of systemic iron deficiency or anemia in the Tmprss6-/- mice. Tmprss6-/-Fgf23+/eGFP mice showed green fluorescence in the vascular regions of BM sections and showed a subset of BM endothelial cells that were GFPbright by flow cytometry. Mining of transcriptomic data sets from mice with normal iron balance revealed higher Fgf23 mRNA in BM sinusoidal endothelial cells (BM-SECs) than that in other BM endothelial cell populations. Anti-GFP immunohistochemistry of fixed BM sections from Tmprss6-/-Fgf23+/eGFP mice revealed GFP expression in BM-SECs, which was more intense than in nonanemic controls. In addition, in mice with intact Tmprss6 alleles, Fgf23-eGFP reporter expression increased in BM-SECs following large-volume phlebotomy and also following erythropoietin treatment both ex vivo and in vivo. Collectively, our results identified BM-SECs as a novel site for Fgf23 upregulation in both acute and chronic anemia. Given the elevated serum erythropoietin in both anemic models, our findings raise the possibility that erythropoietin may act directly on BM-SECs to promote FGF23 production during anemia.
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Affiliation(s)
- Xiuqi Li
- Department of Pathology, Yale School of Medicine, New Haven, CT
| | | | - Steven M. Tommasini
- Department of Orthopaedics & Rehabilitation, Yale School of Medicine, New Haven, CT
| | - Jackie Fretz
- Department of Orthopaedics & Rehabilitation, Yale School of Medicine, New Haven, CT
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13
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Grino M, Rigaux M, Lagarde AV, Robert V, Papailhau C, Vincentelli MB. [Hypophosphatemia after injectable iron treatments in adults: Comparison between ferric carboxymaltose and iron sucrose]. ANNALES PHARMACEUTIQUES FRANÇAISES 2023; 81:790-800. [PMID: 36963655 DOI: 10.1016/j.pharma.2023.03.003] [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: 01/23/2023] [Revised: 03/13/2023] [Accepted: 03/20/2023] [Indexed: 03/26/2023]
Abstract
Hypophosphatemia is a recognized side effect of treatment of iron deficiency anemias with injectable iron. We analyzed 35 clinical trials that used ferric carboxymaltose (FCM) or iron sucrose (IS). Hypophosphatemia prevalence ranged from 0 to 91.7%. FCM-induced a significant (P<0.001) greater hypophosphatemia prevalence and phosphatemia decrease than IS (52.0% [95% CI: 42.2-61.8%] vs. 7.7% [95% CI: -2.8 to 18.2%] and -1.12mmol/L [95% CI: -1.36 to -0.89mmol/L] vs. -0.13mmol/L [95% CI: -0.59 to 0.32mmol/L]). FCM-induced hypophosphatemia was dose-dependent. The nadir of hypophosphatemia was reached in almost all studies after 7 and 14days. Hypophosphatemia persisted at the end of the study in 53.8% of the reported studies that used FCM and lasted up to 6months. FCM-induced an increase in intact circulating fibroblast growth factor 23 and in renal phosphorus excretion while serum 1-25 dihydroxyvitamin D was decreased. Risk factors for hypophosphatemia after FCM therapy were low basal circulating phosphate or ferritin, low body weight, high glomerular filtration rate, serum parathyroid hormone or hemoglobin and age, whereas renal insufficiency was associated with a lower risk. In conclusion, hypophosphatemia is common after treatment with injectable iron, FCM being associated with a higher risk than IS and with disorders of phosphocalcium metabolism. Monitoring of blood phosphate and 1-25 dihydroxyvitamin D could be considered during FCM therapy.
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Affiliation(s)
- Michel Grino
- Département de recherche clinique, Centre gérontologique départemental de Marseille, 176, avenue de Montolivet, 13012 Marseille, France.
| | - Marine Rigaux
- Pharmacie à usage intérieur, Centre gérontologique départemental de Marseille, 176, avenue de Montolivet, 13012 Marseille, France
| | - Anne-Violette Lagarde
- Pharmacie à usage intérieur, Centre gérontologique départemental de Marseille, 176, avenue de Montolivet, 13012 Marseille, France
| | - Vincent Robert
- Pharmacie à usage intérieur, Centre gérontologique départemental de Marseille, 176, avenue de Montolivet, 13012 Marseille, France
| | - Charlotte Papailhau
- Pharmacie à usage intérieur, Centre gérontologique départemental de Marseille, 176, avenue de Montolivet, 13012 Marseille, France
| | - Marie-Bénédicte Vincentelli
- Pharmacie à usage intérieur, Centre gérontologique départemental de Marseille, 176, avenue de Montolivet, 13012 Marseille, France
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14
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Courbon G, Thomas JJ, Martinez-Calle M, Wang X, Spindler J, Von Drasek J, Hunt-Tobey B, Mehta R, Isakova T, Chang W, Creemers JWM, Ji P, Martin A, David V. Bone-derived C-terminal FGF23 cleaved peptides increase iron availability in acute inflammation. Blood 2023; 142:106-118. [PMID: 37053547 PMCID: PMC10356820 DOI: 10.1182/blood.2022018475] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 03/24/2023] [Accepted: 04/06/2023] [Indexed: 04/15/2023] Open
Abstract
Inflammation leads to functional iron deficiency by increasing the expression of the hepatic iron regulatory peptide hepcidin. Inflammation also stimulates fibroblast growth factor 23 (FGF23) production by increasing both Fgf23 transcription and FGF23 cleavage, which paradoxically leads to excess in C-terminal FGF23 peptides (Cter-FGF23), rather than intact FGF23 (iFGF23) hormone. We determined that the major source of Cter-FGF23 is osteocytes and investigated whether Cter-FGF23 peptides play a direct role in the regulation of hepcidin and iron metabolism in response to acute inflammation. Mice harboring an osteocyte-specific deletion of Fgf23 showed a ∼90% reduction in Cter-FGF23 levels during acute inflammation. Reduction in Cter-FGF23 led to a further decrease in circulating iron in inflamed mice owing to excessive hepcidin production. We observed similar results in mice showing impaired FGF23 cleavage owing to osteocyte-specific deletion of Furin. We next showed that Cter-FGF23 peptides bind members of the bone morphogenetic protein (BMP) family, BMP2 and BMP9, which are established inducers of hepcidin. Coadministration of Cter-FGF23 and BMP2 or BMP9 prevented the increase in Hamp messenger RNA and circulating hepcidin levels induced by BMP2/9, resulting in normal serum iron levels. Finally, injection of Cter-FGF23 in inflamed Fgf23KO mice and genetic overexpression of Cter-Fgf23 in wild type mice also resulted in lower hepcidin and higher circulating iron levels. In conclusion, during inflammation, bone is the major source of Cter-FGF23 secretion, and independently of iFGF23, Cter-FGF23 reduces BMP-induced hepcidin secretion in the liver.
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Affiliation(s)
- Guillaume Courbon
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Jane Joy Thomas
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Marta Martinez-Calle
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Xueyan Wang
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Jadeah Spindler
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - John Von Drasek
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Bridget Hunt-Tobey
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Rupal Mehta
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Tamara Isakova
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Wenhan Chang
- Endocrine Research Unit, San Francisco Veterans Affairs Medical Center, University of California San Francisco, San Francisco, CA
| | | | - Peng Ji
- Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Aline Martin
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Valentin David
- Division of Nephrology and Hypertension, Department of Medicine, Center for Translational Metabolism and Health, Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL
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15
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Clinkenbeard E. Fibroblast Growth Factor 23 Bone Regulation and Downstream Hormonal Activity. Calcif Tissue Int 2023; 113:4-20. [PMID: 37306735 DOI: 10.1007/s00223-023-01092-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Accepted: 05/01/2023] [Indexed: 06/13/2023]
Abstract
Mineral homeostasis of calcium and phosphate levels is one critical component to the maintenance of bone mineral density (BMD) and strength. Diseases that disrupt calcium and phosphate balanced have highlighted not only the role these minerals play in overall bone homeostasis, but also the factors, hormones and downstream transporters, responsible for mineral metabolism. The key phosphaturic hormone elucidated from studying rare heritable disorders of hypophosphatemia is Fibroblast Growth Factor 23 (FGF23). FGF23 is predominantly secreted from bone cells in an effort to maintain phosphate balance by directly controlling renal reabsorption and indirectly affecting intestinal uptake of this mineral. Multiple factors have been shown to enhance bone mRNA expression; however, FGF23 can also undergo proteolytic cleavage to control secretion of the biologically active form of the hormone. The review focuses specifically on the regulation of FGF23 and its secretion from bone as well as its hormonal actions under physiological and disease conditions.
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Affiliation(s)
- Erica Clinkenbeard
- Department of Medical and Molecular Genetics, School of Medicine, Indiana University, 635 Barnhill Drive MS 5023, Indianapolis, IN, 46202, USA.
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16
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Yang J, Li Q, Feng Y, Zeng Y. Iron Deficiency and Iron Deficiency Anemia: Potential Risk Factors in Bone Loss. Int J Mol Sci 2023; 24:ijms24086891. [PMID: 37108056 PMCID: PMC10138976 DOI: 10.3390/ijms24086891] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/01/2023] [Accepted: 04/03/2023] [Indexed: 04/29/2023] Open
Abstract
Iron is one of the essential mineral elements for the human body and this nutrient deficiency is a worldwide public health problem. Iron is essential in oxygen transport, participates in many enzyme systems in the body, and is an important trace element in maintaining basic cellular life activities. Iron also plays an important role in collagen synthesis and vitamin D metabolism. Therefore, decrease in intracellular iron can lead to disturbance in the activity and function of osteoblasts and osteoclasts, resulting in imbalance in bone homeostasis and ultimately bone loss. Indeed, iron deficiency, with or without anemia, leads to osteopenia or osteoporosis, which has been revealed by numerous clinical observations and animal studies. This review presents current knowledge on iron metabolism under iron deficiency states and the diagnosis and prevention of iron deficiency and iron deficiency anemia (IDA). With emphasis, studies related to iron deficiency and bone loss are discussed, and the potential mechanisms of iron deficiency leading to bone loss are analyzed. Finally, several measures to promote complete recovery and prevention of iron deficiency are listed to improve quality of life, including bone health.
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Affiliation(s)
- Jiancheng Yang
- Department of Osteoporosis, Honghui Hospital, Xi'an Jiaotong University, Xi'an 710054, China
| | - Qingmei Li
- Department of Osteoporosis, Honghui Hospital, Xi'an Jiaotong University, Xi'an 710054, China
| | - Yan Feng
- Department of Osteoporosis, Honghui Hospital, Xi'an Jiaotong University, Xi'an 710054, China
| | - Yuhong Zeng
- Department of Osteoporosis, Honghui Hospital, Xi'an Jiaotong University, Xi'an 710054, China
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17
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Pons-Belda OD, Alonso-Álvarez MA, González-Rodríguez JD, Mantecón-Fernández L, Santos-Rodríguez F. Mineral Metabolism in Children: Interrelation between Vitamin D and FGF23. Int J Mol Sci 2023; 24:ijms24076661. [PMID: 37047636 PMCID: PMC10094813 DOI: 10.3390/ijms24076661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 03/29/2023] [Accepted: 04/01/2023] [Indexed: 04/05/2023] Open
Abstract
Fibroblast growth factor 23 (FGF23) was identified at the turn of the century as the long-sought circulating phosphatonin in human pathology. Since then, several clinical and experimental studies have investigated the metabolism of FGF23 and revealed its relevant pathogenic role in various diseases. Most of these studies have been performed in adult individuals. However, the mineral metabolism of the child is, to a large extent, different from that of the adult because, in addition to bone remodeling, the child undergoes a specific process of endochondral ossification responsible for adequate mineralization of long bones’ metaphysis and growth in height. Vitamin D metabolism is known to be deeply involved in these processes. FGF23 might have an influence on bones’ growth as well as on the high and age-dependent serum phosphate concentrations found in infancy and childhood. However, the interaction between FGF23 and vitamin D in children is largely unknown. Thus, this review focuses on the following aspects of FGF23 metabolism in the pediatric age: circulating concentrations’ reference values, as well as those of other major variables involved in mineral homeostasis, and the relationship with vitamin D metabolism in the neonatal period, in vitamin D deficiency, in chronic kidney disease (CKD) and in hypophosphatemic disorders.
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Affiliation(s)
| | | | | | | | - Fernando Santos-Rodríguez
- Hospital Universitario Central de Asturias, 33011 Oviedo, Spain
- Department of Medicine, Faculty of Medicine, University of Oviedo, 33003 Oviedo, Spain
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18
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Ramos P, Larson B, Ashrafzadeh-Kian S, Ito N, Kato H, Bornhorst JA, Algeciras-Schimnich A. Intact Fibroblast Growth Factor 23 Concentrations in Hypophosphatemic Disorders. Endocr Pract 2023; 29:193-198. [PMID: 36627024 DOI: 10.1016/j.eprac.2023.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 12/23/2022] [Accepted: 01/03/2023] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Evaluation of circulating fibroblast growth factor 23 (FGF23) concentrations plays a key role in the differential diagnosis of patients presenting with hypophosphatemia. FGF23 concentrations obtained by different immunoassays are not comparable and subsequently, differences in the clinical performance of the assays might arise. In this study, we evaluated the clinical performance of the Medfrontier FGF23 Intact immunoassay (MedFrontier, Minaris Medical Co, Ltd, Tokyo, Japan) in clinically relevant hypophosphatemic conditions. METHODS Intact FGF23 (iFGF23) was measured in serum samples from 61 patients with FGF23-dependent hypophosphatemia (42-tumor induced osteomalacia [TIO] and 19-X-linked hypophosphatemia [XLH]); 8 patients with FGF23-independent hypophosphatemia (6-Fanconi Syndrome and 2-Vitamin D dependent rickets); 10 normophosphatemic patients; 15 chronic kidney disease (CKD) stage-2/3 and 20 CKD stage-4/5 patients; and a healthy control population. Disease-specific differences in measured iFGF23 concentrations and FGF23 concentration association with phosphate concentrations were reported. RESULTS iFGF23 concentrations were significantly elevated in 90% and 84% of TIO and XLH hypophosphatemia patients as compared to healthy controls (both TIO and XLH, P = .0001). There was no significant correlation between iFGF23 and phosphate concentrations (P = .74 and P = .86) for TIO and XLH, respectively. Patients with CKD showed a significant increase in serum iFGF23 as the estimated glomerular filtration rate decreased (ρ = -0.79, P ≤ 0.0001). CONCLUSIONS This study evaluated the clinical performance of the MedFrontier iFGF23 assay in a large cohort of XLH and TIO Caucasian and Asian patients. The clinical sensitivity of this iFGF23 assay is appropriate for clinical use.
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Affiliation(s)
- Paola Ramos
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Bethany Larson
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | | | - Nobuaki Ito
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo, Japan; Osteoporosis Center, The University of Tokyo Hospital, Tokyo, Japan
| | - Hajime Kato
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, Tokyo, Japan; Osteoporosis Center, The University of Tokyo Hospital, Tokyo, Japan
| | - Joshua A Bornhorst
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
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19
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Chaturvedi S, Vijayakumar TS, Job V, Mahendri NV, Salusky I, Agarwal I. A Cross-sectional Study on Fibroblast Growth Factor 23 and Other Markers of Mineral Metabolism in Healthy Children in India. SAUDI JOURNAL OF KIDNEY DISEASES AND TRANSPLANTATION 2023; 34:147-153. [PMID: 38146724 DOI: 10.4103/1319-2442.391893] [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: 12/27/2023] Open
Abstract
Fibroblast growth factor 23 (FGF23) plays a significant role in phosphate homeostasis but data on children are limited. We aimed to detect FGF23 levels in 107 healthy children aged 6-16 years and evaluate its correlation with markers of phosphate and calcium metabolism, and the dietary intake of calcium, phosphate, and proteins. Height, weight, and Tanner stages were measured, and dietary intake was calculated. Biochemical analyses of hemoglobin, serum calcium, phosphate, creatinine, Vitamin D, and plasma parathyroid hormone (PTH) and FGF23 levels were performed, alongside their associations with FGF23. Of the children, 65.4% were males. Their mean body mass index was 15.79 ± 2.96 for males and 16.5 ± SD 2.72 for females. The mean Vitamin D and PTH levels were 29.7 ± 1.1 ng/mL and 29.2 ± 1.2 pg/mL, respectively. The mean FGF23 levels were 159 ± 15.2 reference units (RU)/mL. The mean FGF23 levels were significantly higher in females (209.3 ± 31 RU/mL) than in males (132.3 ± 15.1 RU/mL). All biochemical parameters were within the normal range. FGF23 correlated with age, weight, and height, but not Vitamin D, PTH, or dietary calcium and phosphate. FGF23 showed a negative correlation with hemoglobin levels (r = -0.23). Since most children had a nonvegetarian diet, the FGF23 levels were not assessed in vegetarians. These observations were attributed to the rural lifestyle favoring adequate exposure to sunlight and physical activity. The increased FGF23 levels in females, the trends in urban settings, and the levels in strictly vegetarian diets need further study.
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Affiliation(s)
| | | | - Victoria Job
- Department of Clinical Biochemistry, Christian Medical College, Vellore, India
| | - N V Mahendri
- Department of Dietary, Christian Medical College, Vellore, India
| | - Isidro Salusky
- Department of Pediatric Nephrology, David Geffen School of Medicine UCLA, CA, USA
| | - Indira Agarwal
- Department of Pediatrics, Christian Medical College, Vellore, India
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20
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Fibroblastic growth factor 23 linking iron and bone metabolism. Hypothesis on how FGF23 is effected by blood donation. Transfus Apher Sci 2023; 62:103672. [PMID: 36870910 DOI: 10.1016/j.transci.2023.103672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
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21
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FGF23 in Chronic Kidney Disease: Bridging the Heart and Anemia. Cells 2023; 12:cells12040609. [PMID: 36831276 PMCID: PMC9954184 DOI: 10.3390/cells12040609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/09/2023] [Accepted: 02/10/2023] [Indexed: 02/16/2023] Open
Abstract
Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone produced mainly in osteocytes. In chronic kidney disease (CKD) FGF23 levels increase due to higher production, but also as the result of impaired cleavage and reduced excretion from the body. FGF23 has a significant role in disturbed bone and mineral metabolism in CKD, which leads to a higher cardiovascular risk and mortality in these patients. Current research has emphasized the expression of FGF23 in cardiac myocytes, fibroblasts, and endothelial cells, and in addition to the effects on the kidney, its primary role is in cardiac remodeling in CKD patients. Recent discoveries found a significant link between increased FGF23 levels and anemia development in CKD. This review describes the FGF23 role in cardiac hypertrophy and anemia in the setting of CKD and discusses the best therapeutical approach for lowering FGF23 levels.
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22
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Kato H, Miyazaki H, Kimura T, Hoshino Y, Hidaka N, Koga M, Nangaku M, Makita N, Ito N. Clinical performance of a new intact FGF23 immunoassay in healthy individuals and patients with chronic hypophosphatemia. Bone Rep 2023; 18:101659. [PMID: 36817167 PMCID: PMC9932357 DOI: 10.1016/j.bonr.2023.101659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 01/30/2023] [Accepted: 02/01/2023] [Indexed: 02/05/2023] Open
Abstract
While the positive association between automated intact fibroblast growth factor (FGF) 23 measurement kit (Determinar CL FGF23 [CL]) and the former assay (Kainos [KI]), and clinical utility of CL was well established, the clinical performance of Medfrontier FGF23 (MED), which was the manual intact FGF23 measurement kit with same antibody set as CL, has not yet been validated. Therefore, this study aims to compare MED FGF23 levels to KI FGF23 levels. A total of 380 samples were collected from healthy individuals, and 200 samples were collected from 20 patients with chronic hypophosphatemia. The intact FGF23 level of each sample was measured by KI and MED. Among the healthy individuals, the reference range of MED FGF23 levels was 18.6-59.8 pg/mL when calculated as the average ± 2 standard deviations. When compared with KI FGF23 levels, MED FGF23 levels were lower than KI levels both among samples from healthy individuals (KI FGF23, 40.9 [interquartile (IQR), 31.1-50.6]; MED FGF23, 38.0 [IQR, 31.5-45.7]; p value = 0.02) and among samples from patients with chronic hypophosphatemia (KI FGF23, 172.5 [IQR, 115.8-290.7]; MED FGF23, 130.2 [IQR, 93.6-247.0]; p value = 0.003). The linear regression analysis showed that the correlation between KI FGF23 and MED FGF23 was interpreted as a slope of 0.83 with a y-intercept of 0.53, revealing good linearity (R2 = 0.99). This study showed that the discrepancy between KI and MED was very similar to the previously reported data between KI and CL.
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Affiliation(s)
- Hajime Kato
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan,Osteoporosis Center, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Hiromi Miyazaki
- Minaris Medical Co., Ltd., 600-1, Minami-ishiki, Nagaizumi-cho, Sunto-gun, Shizuoka 411-0932, Japan
| | - Takehide Kimura
- Minaris Medical Co., Ltd., 600-1, Minami-ishiki, Nagaizumi-cho, Sunto-gun, Shizuoka 411-0932, Japan
| | - Yoshitomo Hoshino
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan,Osteoporosis Center, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Naoko Hidaka
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan,Osteoporosis Center, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Minae Koga
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan,Osteoporosis Center, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Noriko Makita
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan,Osteoporosis Center, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
| | - Nobuaki Ito
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan,Osteoporosis Center, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan,Corresponding author at: Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
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23
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Noonan ML, Ni P, Solis E, Marambio YG, Agoro R, Chu X, Wang Y, Gao H, Xuei X, Clinkenbeard EL, Jiang G, Liu S, Stegen S, Carmeliet G, Thompson WR, Liu Y, Wan J, White KE. Osteocyte Egln1/Phd2 links oxygen sensing and biomineralization via FGF23. Bone Res 2023; 11:7. [PMID: 36650133 PMCID: PMC9845350 DOI: 10.1038/s41413-022-00241-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 09/29/2022] [Accepted: 11/03/2022] [Indexed: 01/19/2023] Open
Abstract
Osteocytes act within a hypoxic environment to control key steps in bone formation. FGF23, a critical phosphate-regulating hormone, is stimulated by low oxygen/iron in acute and chronic diseases, however the molecular mechanisms directing this process remain unclear. Our goal was to identify the osteocyte factors responsible for FGF23 production driven by changes in oxygen/iron utilization. Hypoxia-inducible factor-prolyl hydroxylase inhibitors (HIF-PHI) which stabilize HIF transcription factors, increased Fgf23 in normal mice, as well as in osteocyte-like cells; in mice with conditional osteocyte Fgf23 deletion, circulating iFGF23 was suppressed. An inducible MSC cell line ('MPC2') underwent FG-4592 treatment and ATACseq/RNAseq, and demonstrated that differentiated osteocytes significantly increased HIF genomic accessibility versus progenitor cells. Integrative genomics also revealed increased prolyl hydroxylase Egln1 (Phd2) chromatin accessibility and expression, which was positively associated with osteocyte differentiation. In mice with chronic kidney disease (CKD), Phd1-3 enzymes were suppressed, consistent with FGF23 upregulation in this model. Conditional loss of Phd2 from osteocytes in vivo resulted in upregulated Fgf23, in line with our findings that the MPC2 cell line lacking Phd2 (CRISPR Phd2-KO cells) constitutively activated Fgf23 that was abolished by HIF1α blockade. In vitro, Phd2-KO cells lost iron-mediated suppression of Fgf23 and this activity was not compensated for by Phd1 or -3. In sum, osteocytes become adapted to oxygen/iron sensing during differentiation and are directly sensitive to bioavailable iron. Further, Phd2 is a critical mediator of osteocyte FGF23 production, thus our collective studies may provide new therapeutic targets for skeletal diseases involving disturbed oxygen/iron sensing.
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Affiliation(s)
- Megan L Noonan
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Pu Ni
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Emmanuel Solis
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Yamil G Marambio
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Rafiou Agoro
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Xiaona Chu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Yue Wang
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Hongyu Gao
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Xiaoling Xuei
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Erica L Clinkenbeard
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Guanglong Jiang
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Sheng Liu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Steve Stegen
- Laboratory of Clinical and Experimental Endocrinology, Department of Chronic Diseases and Metabolism, KU Leuven, 3000, Leuven, Belgium
| | - Geert Carmeliet
- Laboratory of Clinical and Experimental Endocrinology, Department of Chronic Diseases and Metabolism, KU Leuven, 3000, Leuven, Belgium
| | - William R Thompson
- Department of Physical Therapy, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Yunlong Liu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Center for Computational Biology and Bioinformatics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Jun Wan
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Kenneth E White
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Departments of Medicine/Division of Nephrology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
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Michigami T. Paracrine and endocrine functions of osteocytes. Clin Pediatr Endocrinol 2023; 32:1-10. [PMID: 36761497 PMCID: PMC9887291 DOI: 10.1297/cpe.2022-0053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/30/2022] [Indexed: 11/04/2022] Open
Abstract
Osteocytes are dendritic-shaped cells embedded in the bone matrix and are terminally differentiated from osteoblasts. Inaccessibility due to their location has hindered the understanding of the molecular functions of osteocytes. However, scientific advances in the past few decades have revealed that osteocytes play critical roles in bone and mineral metabolism through their paracrine and endocrine functions. Sclerostin produced by osteocytes regulates bone formation and resorption by inhibiting Wnt/β-catenin signaling in osteoblast-lineage cells. Receptor activator of nuclear factor κ B ligand (RANKL) derived from osteocytes is essential for osteoclastogenesis and osteoclast activation during postnatal life. Osteocytes also secrete fibroblast growth factor 23 (FGF23), an endocrine FGF that regulates phosphate metabolism mainly by increasing phosphate excretion and decreasing 1, 25-dihydroxyvitamin D production in the kidneys. The regulation of FGF23 production in osteocytes is complex and multifactorial, involving many local and systemic regulators. Antibodies against sclerostin, RANKL, and FGF23 have emerged as new strategies for the treatment of metabolic bone diseases. Improved undrstanding of the paracrine and endocrine functions of osteocytes will provide insight into future therapeutic options.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute,
Osaka Women’s and Children’s Hospital, Osaka Prefectural Hospital Organization, Osaka,
Japan
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Abstract
Hypophosphatemic rickets typically presents in infancy or early childhood with skeletal deformities and growth plate abnormalities. The most common causes are genetic (such as X-linked hypophosphatemia), and these typically will result in lifelong hypophosphatemia and osteomalacia. Knowledge of phosphate metabolism, including the effects of fibroblast growth factor 23 (FGF23) (an osteocyte produced hormone that downregulates renal phosphate reabsorption and 1,25-dihydroxyvitamin-D (1,25(OH)2D) production), is critical to determining the underlying genetic or acquired causes of hypophosphatemia and to facilitate appropriate treatment. Serum phosphorus should be measured in any child or adult with musculoskeletal complaints suggesting rickets or osteomalacia. Clinical evaluation incudes thorough history, physical examination, laboratory investigations, genetic analysis (especially in the absence of a guiding family history), and imaging to establish etiology and to monitor severity and treatment course. The treatment depends on the underlying cause, but often includes active forms of vitamin D combined with phosphate salts, or anti-FGF23 antibody treatment (burosumab) for X-linked hypophosphatemia. The purpose of this article is to explore the approach to evaluating hypophosphatemic rickets and its treatment options.
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Affiliation(s)
- Sarah A Ackah
- Department of Medicine, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Erik A Imel
- Department of Medicine, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Li H, Hu SM, Li YM, Ciancio G, Tadros NN, Tao Y, Bai YJ, Shi YY. Beneficial effect of roxadustat on early posttransplant anemia and iron utilization in kidney transplant recipients: a retrospective comparative cohort study. ANNALS OF TRANSLATIONAL MEDICINE 2022; 10:1360. [PMID: 36660711 PMCID: PMC9843359 DOI: 10.21037/atm-22-5897] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 12/16/2022] [Indexed: 12/29/2022]
Abstract
Background Although posttransplant anemia (PTA) is a common complication after kidney transplant, it has not been thoroughly evaluated for appropriate treatment. Roxadustat can stimulate erythropoiesis by increasing erythropoietin (EPO) production and improving the utilization of iron. However, there are currently a few case reports describing its effect on PTA in kidney transplant recipients (KTRs). Our purpose was to evaluate the efficacy and safety of roxadustat in KTRs with PTA. Methods In this retrospective study, KTRs with early PTA were divided into a roxadustat group, erythropoiesis-stimulating agent (ESA) group, and untreated group (neither roxadustat nor ESA) according to the treatment prescribed by their physicians. We compared the levels of hemoglobin (Hb), creatinine, lipids, hepcidin, intact fibroblast growth factor 23 (iFGF23) and iron-related indices, at baseline and different time points posttransplant. Outcome was assessed at both month 3 and month 12 posttransplant. Adverse events during the treatment course were also recorded. Results A total of 57 KTRs were included (n=22 roxadustat group, n=13 ESA group, n=22 untreated group). There was no difference in age, sex, body mass index, dialysis method and duration, donor type among three groups at baseline. The mean Hb levels at month 3 posttransplant (128.00±19.62 vs. 118.59±11.60 g/L, P=0.048) and the average change in Hb levels from week 2 to month 3 (48.05±22.53 vs. 31.45±12.96 g/L, P=0.005) in the roxadustat group were significantly higher than those in the untreated group. However, there was no significant difference in the above indices between the roxadustat and ESA groups. At month 3, the total iron binding capacity (TIBC) and levels of transferrin were significantly higher while levels of ferritin, hepcidin and iFGF23 were significantly lower in the roxadustat group than in other groups (P<0.05). No significant difference was found in creatinine or estimated glomerular filtration rate (eGFR) levels among the three groups at month 3. During the follow-up, no adverse events related to roxadustat were reported. Conclusions Administration of roxadustat in KTRs with early PTA could elevate Hb levels effectively and safely by enhancing endogenous EPO production and improving iron utilization. Further randomized studies with larger sample size are necessary to verify our results.
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Affiliation(s)
- Hui Li
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China
| | - Shu-Meng Hu
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China
| | - Ya-Mei Li
- Department of Laboratory Medicine/Research Centre of Clinical Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Gaetano Ciancio
- Department of Surgery and Urology, Miami Transplant Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | | | - Ye Tao
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China
| | - Yang-Juan Bai
- Department of Laboratory Medicine/Research Centre of Clinical Laboratory Medicine, West China Hospital, Sichuan University, Chengdu, China
| | - Yun-Ying Shi
- Department of Nephrology, West China Hospital, Sichuan University, Chengdu, China
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Abstract
Inorganic phosphate (Pi) in the mammalian body is balanced by its influx and efflux through the intestines, kidneys, bones, and soft tissues, at which several sodium/Pi co-transporters mediate its active transport. Pi homeostasis is achieved through the complex counter-regulatory feedback balance between fibroblast growth factor 23 (FGF23), 1,25-dihydroxyvitamin D (1,25(OH)2D), and parathyroid hormone. FGF23, which is mainly produced by osteocytes in bone, plays a central role in Pi homeostasis and exerts its effects by binding to the FGF receptor (FGFR) and αKlotho in distant target organs. In the kidneys, the main target, FGF23 promotes the excretion of Pi and suppresses the production of 1,25(OH)2D. Deficient and excess FGF23 result in hyperphosphatemia and hypophosphatemia, respectively. FGF23-related hypophosphatemic rickets/osteomalacia include tumor-induced osteomalacia and various genetic diseases, such as X-linked hypophosphatemic rickets. Coverage by the national health insurance system in Japan for the measurement of FGF23 and the approval of burosumab, an FGF23-neutralizing antibody, have had a significant impact on the diagnosis and treatment of FGF23-related hypophosphatemic rickets/osteomalacia. Some of the molecules responsible for genetic hypophosphatemic rickets/osteomalacia are highly expressed in osteocytes and function as local regulators of FGF23 production. A number of systemic factors also regulate FGF23 levels. Although the mechanisms responsible for Pi sensing in mammals have not yet been elucidated in detail, recent studies have suggested the involvement of FGFR1. The further clarification of the mechanisms by which osteocytes detect Pi levels and regulate FGF23 production will lead to the development of better strategies to treat hyperphosphatemic and hypophosphatemic conditions.
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Affiliation(s)
- Toshimi Michigami
- Department of Bone and Mineral Research, Research Institute, Osaka Women's and Children's Hospital, Osaka 594-1101, Japan
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Collins MT, Marcucci G, Anders HJ, Beltrami G, Cauley JA, Ebeling PR, Kumar R, Linglart A, Sangiorgi L, Towler DA, Weston R, Whyte MP, Brandi ML, Clarke B, Thakker RV. Skeletal and extraskeletal disorders of biomineralization. Nat Rev Endocrinol 2022; 18:473-489. [PMID: 35578027 DOI: 10.1038/s41574-022-00682-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/13/2022] [Indexed: 12/15/2022]
Abstract
The physiological process of biomineralization is complex and deviation from it leads to a variety of diseases. Progress in the past 10 years has enhanced understanding of the genetic, molecular and cellular pathophysiology underlying these disorders; sometimes, this knowledge has both facilitated restoration of health and clarified the very nature of biomineralization as it occurs in humans. In this Review, we consider the principal regulators of mineralization and crystallization, and how dysregulation of these processes can lead to human disease. The knowledge acquired to date and gaps still to be filled are highlighted. The disorders of mineralization discussed comprise a broad spectrum of conditions that encompass bone disorders associated with alterations of mineral quantity and quality, as well as disorders of extraskeletal mineralization (hyperphosphataemic familial tumoural calcinosis). Included are disorders of alkaline phosphatase (hypophosphatasia) and phosphate homeostasis (X-linked hypophosphataemic rickets, fluorosis, rickets and osteomalacia). Furthermore, crystallopathies are covered as well as arterial and renal calcification. This Review discusses the current knowledge of biomineralization derived from basic and clinical research and points to future studies that will lead to new therapeutic approaches for biomineralization disorders.
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Affiliation(s)
- Michael T Collins
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, NIH, Bethesda, MD, USA.
| | - Gemma Marcucci
- Bone Metabolic Diseases Unit, Department of Biomedical, Experimental and Clinical Sciences, University of Florence, Florence, Italy
| | - Hans-Joachim Anders
- Department of Medicine IV, Hospital of the University of Munich, Ludwig-Maximilians University, Munich, Germany
| | - Giovanni Beltrami
- Department Paediatric Orthopedic Oncology, Careggi and Meyer Children Hospital, Florence, Italy
| | - Jane A Cauley
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Peter R Ebeling
- Department of Medicine, School of Clinical Sciences, Monash University, Melbourne, Australia
| | - Rajiv Kumar
- Departments of Medicine, Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Agnès Linglart
- APHP, Endocrinologie et diabète de l'enfant, Paris, France
| | - Luca Sangiorgi
- Medical Genetics and Skeletal Rare Diseases, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy
| | - Dwight A Towler
- University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ria Weston
- Cardiovascular Research Group, Manchester Metropolitan University, Manchester, UK
| | - Michael P Whyte
- Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children-St Louis, St Louis, MO, USA
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO, USA
| | | | - Bart Clarke
- Mayo Clinic Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Rochester, MN, USA
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
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29
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Pathogenesis of FGF23-Related Hypophosphatemic Diseases Including X-linked Hypophosphatemia. ENDOCRINES 2022. [DOI: 10.3390/endocrines3020025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Since phosphate is indispensable for skeletal mineralization, chronic hypophosphatemia causes rickets and osteomalacia. Fibroblast growth factor 23 (FGF23), which is mainly produced by osteocytes in bone, functions as the central regulator of phosphate metabolism by increasing the renal excretion of phosphate and suppressing the production of 1,25-dihydroxyvitamin D. The excessive action of FGF23 results in hypophosphatemic diseases, which include a number of genetic disorders such as X-linked hypophosphatemic rickets (XLH) and tumor-induced osteomalacia (TIO). Phosphate-regulating gene homologous to endopeptidase on the X chromosome (PHEX), dentin matrix protein 1 (DMP1), ectonucleotide pyrophosphatase phosphodiesterase-1, and family with sequence similarity 20c, the inactivating variants of which are responsible for FGF23-related hereditary rickets/osteomalacia, are highly expressed in osteocytes, similar to FGF23, suggesting that they are local negative regulators of FGF23. Autosomal dominant hypophosphatemic rickets (ADHR) is caused by cleavage-resistant variants of FGF23, and iron deficiency increases serum levels of FGF23 and the manifestation of symptoms in ADHR. Enhanced FGF receptor (FGFR) signaling in osteocytes is suggested to be involved in the overproduction of FGF23 in XLH and autosomal recessive hypophosphatemic rickets type 1, which are caused by the inactivation of PHEX and DMP1, respectively. TIO is caused by the overproduction of FGF23 by phosphaturic tumors, which are often positive for FGFR. FGF23-related hypophosphatemia may also be associated with McCune-Albright syndrome, linear sebaceous nevus syndrome, and the intravenous administration of iron. This review summarizes current knowledge on the pathogenesis of FGF23-related hypophosphatemic diseases.
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Trombetti A, Al-Daghri N, Brandi ML, Cannata-Andía JB, Cavalier E, Chandran M, Chaussain C, Cipullo L, Cooper C, Haffner D, Harvengt P, Harvey NC, Javaid MK, Jiwa F, Kanis JA, Laslop A, Laurent MR, Linglart A, Marques A, Mindler GT, Minisola S, Yerro MCP, Rosa MM, Seefried L, Vlaskovska M, Zanchetta MB, Rizzoli R. Interdisciplinary management of FGF23-related phosphate wasting syndromes: a Consensus Statement on the evaluation, diagnosis and care of patients with X-linked hypophosphataemia. Nat Rev Endocrinol 2022; 18:366-384. [PMID: 35484227 DOI: 10.1038/s41574-022-00662-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/10/2022] [Indexed: 12/17/2022]
Abstract
X-linked hypophosphataemia (XLH) is the most frequent cause of hypophosphataemia-associated rickets of genetic origin and is associated with high levels of the phosphaturic hormone fibroblast growth factor 23 (FGF23). In addition to rickets and osteomalacia, patients with XLH have a heavy disease burden with enthesopathies, osteoarthritis, pseudofractures and dental complications, all of which contribute to reduced quality of life. This Consensus Statement presents the outcomes of a working group of the European Society for Clinical and Economic Aspects of Osteoporosis, Osteoarthritis and Musculoskeletal Diseases, and provides robust clinical evidence on management in XLH, with an emphasis on patients' experiences and needs. During growth, conventional treatment with phosphate supplements and active vitamin D metabolites (such as calcitriol) improves growth, ameliorates leg deformities and dental manifestations, and reduces pain. The continuation of conventional treatment in symptom-free adults is still debated. A novel therapeutic approach is the monoclonal anti-FGF23 antibody burosumab. Although promising, further studies are required to clarify its long-term efficacy, particularly in adults. Given the diversity of symptoms and complications, an interdisciplinary approach to management is of paramount importance. The focus of treatment should be not only on the physical manifestations and challenges associated with XLH and other FGF23-mediated hypophosphataemia syndromes, but also on the major psychological and social impact of the disease.
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Affiliation(s)
- Andrea Trombetti
- Division of Bone Diseases, Department of Medicine, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
- Division of Geriatrics, Department of Rehabilitation and Geriatrics, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland
| | - Nasser Al-Daghri
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University, Riyadh, Kingdom of Saudi Arabia
| | | | - Jorge B Cannata-Andía
- Hospital Universitario Central de Asturias (HUCA), Oviedo, Spain
- Universidad de Oviedo, Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Spain
- Retic REDinREN-RICORS, 2040-ISCIII, Madrid, Spain
| | - Etienne Cavalier
- Department of Clinical Chemistry, University of Liege, CHU de Liège, Liège, Belgium
| | - Manju Chandran
- Complicated Metabolic Bone Disorders Clinic, Osteoporosis and Bone Metabolism Unit, Department of Endocrinology, Singapore General Hospital, Singapore, Singapore
| | - Catherine Chaussain
- Université de Paris, Institut des maladies musculo-squelettiques, URP2496, UFR Odontologie, Montrouge, France
- AP-HP, FHU DDS-Net, Centre de Référence des Maladies Rares du Métabolisme du Calcium et du Phosphore, Service médecine bucco-dentaire, Hôpital Bretonneau, GH Paris Nord Université de Paris, Paris, France
| | - Lucia Cipullo
- Patient representative with XLH, Geneva, Switzerland
| | - Cyrus Cooper
- MRC Lifecourse Epidemiology Centre, University of Southampton, Southampton, UK
- NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK
- NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Dieter Haffner
- Department of Paediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School, Hannover, Germany
| | - Pol Harvengt
- XLH Belgium, Belgian association of patients with XLH (a member of the International XLH Alliance), Waterloo, Belgium
| | - Nicholas C Harvey
- MRC Lifecourse Epidemiology Centre, University of Southampton, Southampton, UK
- NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, UK
| | | | - Famida Jiwa
- Chair of the Committee of Patients Societies at the International Osteoporosis Foundation, Osteoporosis Canada, Toronto, Canada
| | - John A Kanis
- Mary McKillop Institute for Health Research, Australian Catholic University, Melbourne, Australia
- Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Sheffield, UK
| | - Andrea Laslop
- Scientific Office, Federal Office for Safety in Health Care, Vienna, Austria
| | - Michaël R Laurent
- Centre for Metabolic Bone Diseases, University Hospitals Leuven, Leuven, Belgium
| | - Agnès Linglart
- Paris-Saclay University, INSERM U1185, Le Kremlin-Bicêtre, France
- AP-HP, endocrinology and diabetes for children, Reference centre for rare diseases of calcium and phosphate metabolism, OSCAR network, Platform of expertise for rare diseases of Paris Saclay Hospital, Bicêtre Paris Saclay Hospital, Le Kremlin-Bicêtre, France
| | - Andréa Marques
- Rheumatology Department, Centro Hospitalar Universitário de Coimbra, Coimbra, Portugal
- Health Sciences Research Unit: Nursing (UICiSA:E), Nursing School of Coimbra, Coimbra, Portugal
| | - Gabriel T Mindler
- Department of Paediatric Orthopaedics, Orthopaedic Hospital Speising, Vienna, Austria
- Vienna Bone and Growth Center, Vienna, Austria
| | - Salvatore Minisola
- Department of Clinical, Internal, Anaesthesiologic and Cardiovascular Sciences, 'Sapienza', Rome University, Rome, Italy
| | | | - Mario Miguel Rosa
- Departamento de Neurociências, Laboratório de Farmacologia Clínica E Terapêutica Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Lothar Seefried
- Orthopedic Department, University of Würzburg, Würzburg, Germany
| | - Mila Vlaskovska
- Medical Faculty, Department of Pharmacology, Medical University Sofia, Sofia, Bulgaria
| | - María Belén Zanchetta
- Instituto de Investigaciones Metabólicas (IDIM), Universidad del Salvador, Buenos Aires, Argentina
| | - René Rizzoli
- Division of Bone Diseases, Department of Medicine, Geneva University Hospitals and Faculty of Medicine, Geneva, Switzerland.
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Liesen MP, Noonan ML, Ni P, Agoro R, Hum JM, Clinkenbeard EL, Damrath JG, Wallace JM, Swallow EA, Allen MR, White KE. Segregating the effects of ferric citrate-mediated iron utilization and FGF23 in a mouse model of CKD. Physiol Rep 2022; 10:e15307. [PMID: 35656701 PMCID: PMC9163801 DOI: 10.14814/phy2.15307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 05/03/2022] [Indexed: 11/24/2022] Open
Abstract
Ferric citrate (FC) is an approved therapy for chronic kidney disease (CKD) patients as a phosphate (Pi) binder for dialysis-dependent CKD, and for iron deficiency anemia (IDA) in non-dialysis CKD. Elevated Pi and IDA both lead to increased FGF23, however, the roles of iron and FGF23 during CKD remain unclear. To this end, iron and Pi metabolism were tested in a mouse model of CKD (0.2% adenine) ± 0.5% FC for 6 weeks, with and without osteocyte deletion of Fgf23 (flox-Fgf23/Dmp1-Cre). Intact FGF23 (iFGF23) increased in all CKD mice but was lower in Cre+ mice with or without FC, thus the Dmp1-Cre effectively reduced FGF23. Cre+ mice fed AD-only had higher serum Pi than Cre- pre- and post-diet, and the Cre+ mice had higher BUN regardless of FC treatment. Total serum iron was higher in all mice receiving FC, and liver Tfrc, Bmp6, and hepcidin mRNAs were increased regardless of genotype; liver IL-6 showed decreased mRNA in FC-fed mice. The renal 1,25-dihydroxyvitamin D (1,25D) anabolic enzyme Cyp27b1 had higher mRNA and the catabolic Cyp24a1 showed lower mRNA in FC-fed mice. Finally, mice with loss of FGF23 had higher bone cortical porosity, whereas Raman spectroscopy showed no changes in matrix mineral parameters. Thus, FC- and FGF23-dependent and -independent actions were identified in CKD; loss of FGF23 was associated with higher serum Pi and BUN, demonstrating that FGF23 was protective of mineral metabolism. In contrast, FC maintained serum iron and corrected inflammation mediators, potentially providing ancillary benefit.
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Affiliation(s)
- Michael P. Liesen
- Department of Medical & Molecular GeneticsIndiana University School of MedicineIndianapolisIndianaUSA
- Department of PhysiologyMarian UniversityIndianapolisIndianaUSA
| | - Megan L. Noonan
- Department of Medical & Molecular GeneticsIndiana University School of MedicineIndianapolisIndianaUSA
| | - Pu Ni
- Department of Medical & Molecular GeneticsIndiana University School of MedicineIndianapolisIndianaUSA
| | - Rafiou Agoro
- Department of Medical & Molecular GeneticsIndiana University School of MedicineIndianapolisIndianaUSA
| | - Julia M. Hum
- Department of PhysiologyMarian UniversityIndianapolisIndianaUSA
| | - Erica L. Clinkenbeard
- Department of Medical & Molecular GeneticsIndiana University School of MedicineIndianapolisIndianaUSA
| | - John G. Damrath
- Purdue University Weldon School of Biomedical EngineeringWest LafayetteIndianaUSA
| | - Joseph M. Wallace
- Department of Biomedical EngineeringIndiana University‐Purdue University at IndianapolisIndianapolisIndianaUSA
| | - Elizabeth A. Swallow
- Department of Anatomy, Cell Biology, and PhysiologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Matthew R. Allen
- Department of Biomedical EngineeringIndiana University‐Purdue University at IndianapolisIndianapolisIndianaUSA
- Department of Anatomy, Cell Biology, and PhysiologyIndiana University School of MedicineIndianapolisIndianaUSA
- Department of MedicineDivision of NephrologyIndiana University School of MedicineIndianapolisIndianaUSA
| | - Kenneth E. White
- Department of Medical & Molecular GeneticsIndiana University School of MedicineIndianapolisIndianaUSA
- Department of MedicineDivision of NephrologyIndiana University School of MedicineIndianapolisIndianaUSA
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Vilaca T, Velmurugan N, Smith C, Abrahamsen B, Eastell R. Osteomalacia as a Complication of Intravenous Iron Infusion: A Systematic Review of Case Reports. J Bone Miner Res 2022; 37:1188-1199. [PMID: 35426179 PMCID: PMC9322686 DOI: 10.1002/jbmr.4558] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/18/2022] [Accepted: 04/08/2022] [Indexed: 12/05/2022]
Abstract
Randomized control trials (RCTs) have shown that certain intravenous iron preparations can induce high levels of fibroblast growth factor 23 (FGF-23) and persistent hypophosphatemia. Repeated iron infusions may lead to prolonged hypophosphatemia and osteomalacia events not captured by RCTs. Several previous case reports have described skeletal adverse effects after repeated iron infusions. To characterize these effects, we conducted a systematic review of case reports. MEDLINE, Embase, Web of Science, and Cochrane databases were searched in March 2021. We selected case reports of patients ≥16 years old. Study quality was assessed using the tool from Murad and colleagues. We report the results in a narrative summary. We identified 28 case reports, reporting 30 cases. Ages ranged from 28 to 80 years (median 50 years). Most patients (n = 18) received ferric carboxymaltose (FCM), whereas 8 received saccharated ferric oxide (SFO) and 3 received iron polymaltose (IPM). All but 2 cases had more than five infusions (range 2 to 198, median 17). The lowest phosphate levels ranged from 0.16 to 0.77 mmol/L (median 0.36 mmol/L). Intact FGF-23 (iFGF-23) was high when measured. Serum 25OH vitamin D was low in 10 of 21 cases measured and 1,25(OH)2 vitamin D in 12 of 18. Alkaline phosphatase was high in 18 of 22 cases. Bone or muscle pain was reported in 28 of the 30 cases. Twenty patients had pseudofractures, 9 had fractures, and 6 patients had both. All 15 available bone scans showed focal isotope uptake. Case reports tend to report severe cases, so potential reporting bias should be considered. Osteomalacia is a potential complication of repeated iron infusion, especially in patients with gastrointestinal disorders receiving prolonged therapy. Pain and fractures or pseudofractures are common clinical findings, associated with low phosphate, high iFGF-23, high alkaline phosphatase, and abnormal isotope bone scan. Discontinuing or switching the iron formulation was an effective intervention in most cases. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Tatiane Vilaca
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | | | - Christopher Smith
- Open Patient Data Explorative Network, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Bo Abrahamsen
- Department of Medicine, Holbaek Hospital, Holbaek, Denmark.,Open Patient Data Explorative Network, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Denmark and NDORMS, University of Oxford, Oxford, UK
| | - Richard Eastell
- Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
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Vaculik J, Wenchich L, Bobelyak M, Pavelka K, Stepan JJ. A decrease in serum 1,25(OH) 2D after elective hip replacement and during bone healing is associated with changes in serum iron and plasma FGF23. J Endocrinol Invest 2022; 45:1039-1044. [PMID: 35079976 DOI: 10.1007/s40618-022-01746-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/13/2022] [Indexed: 10/19/2022]
Abstract
OBJECTIVE Although calcitriol is essential for bone healing, its serum concentrations are low after hip surgery, and they continue to decline during bone healing. This study aimed to test the hypothesis of an association of changes in calcitriol production with the status of fibroblast growth factor 23 (FGF23) and iron deficiency after elective hip replacement for coxarthrosis. METHODS In this prospective study, we measured the biomarkers of 17 patients undergoing elective hip replacement on admission, on the first day after surgery, and at the regular check-up after 48 ± 8 days. The serum concentrations of 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, transferrin, ferritin, parathyroid hormone, intact plasma FGF23 (iFGF23) and C-terminal FGF23 (cFGF23) were determined. RESULTS In our patients who underwent elective hip replacement, significant correlations existed between the percent change in the conversion rate of 25(OH)D to 1,25(OH)2D, plasma intact to C-terminal FGF23 ratio, and serum iron. CONCLUSIONS The production of calcitriol is compromised after elective hip replacement surgery, leading to reduced levels of active vitamin D in the serum. Significant correlations between the percent change in the conversion rate of 25(OH)D to 1,25(OH)2D, plasma intact to C-terminal FGF23 ratio, and serum iron on the first day as well as 7 weeks after surgery could inspire future studies to determine whether and how calcitriol deficiency should be corrected, especially in fracture cases.
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Affiliation(s)
- J Vaculik
- Orthopedic Department, Bulovka Hospital, Prague, Czech Republic
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
- Orthopedic Department, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - L Wenchich
- Institute of Rheumatology, Prague, Czech Republic
| | - M Bobelyak
- Orthopedic Department, Bulovka Hospital, Prague, Czech Republic
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - K Pavelka
- Institute of Rheumatology, Prague, Czech Republic
- Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - J J Stepan
- Institute of Rheumatology, Prague, Czech Republic.
- Department of Rheumatology, First Faculty of Medicine, Charles University, Prague, Czech Republic.
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Vervloet MG. Shedding Light on the Complex Regulation of FGF23. Metabolites 2022; 12:metabo12050401. [PMID: 35629904 PMCID: PMC9147863 DOI: 10.3390/metabo12050401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/23/2022] [Accepted: 04/26/2022] [Indexed: 12/10/2022] Open
Abstract
Early research has suggested a rather straightforward relation between phosphate exposure, increased serum FGF23 (Fibroblast Growth Factor 23) concentrations and clinical endpoints. Unsurprisingly, however, subsequent studies have revealed a much more complex interplay between autocrine and paracrine factors locally in bone like PHEX and DMP1, concentrations of minerals in particular calcium and phosphate, calciprotein particles, and endocrine systems like parathyroid hormone PTH and the vitamin D system. In addition to these physiological regulators, an expanding list of disease states are shown to influence FGF23 levels, usually increasing it, and as such increase the burden of disease. While some of these physiological or pathological factors, like inflammatory cytokines, may partially confound the association of FGF23 and clinical endpoints, others are in the same causal path, are targetable and hence hold the promise of future treatment options to alleviate FGF23-driven toxicity, for instance in chronic kidney disease, the FGF23-associated disease with the highest prevalence by far. These factors will be reviewed here and their relative importance described, thereby possibly opening potential means for future therapeutic strategies.
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Affiliation(s)
- Marc G. Vervloet
- Amsterdam UMC, Location Vrije Universiteit Amsterdam, Nephrology, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands; ; Tel.: +31-20-4442671
- Amsterdam Cardiovascular Sciences, Diabetes and Metabolism, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
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Al-Daghri NM, Yakout S, Ghaleb A, Hussain SD, Sabico S. Iron and 25-hydroxyvitamin D in postmenopausal women with osteoporosis. Am J Transl Res 2022; 14:1387-1405. [PMID: 35422903 PMCID: PMC8991132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 01/22/2022] [Indexed: 06/14/2023]
Abstract
Iron and vitamin D deficiencies are some of the most common health problems in the world. Iron is essential in oxygen transport and participates in many enzymatic systems in the body, with important roles in vitamin D metabolism. Osteoporosis is one of the most prevalent chronic disease of the elderly in the world as well as in the Saudi population. The relationship between iron, vitamin D deficiency and bone health comes from clinical observations in iron overload patients who suffered bone loss. The opposite scenario, whether iron and vitamin D deficiencies affect bone metabolism, has not been fully addressed. This is of great interest, as this nutrient deficiency is a worldwide public health problem and at the same time osteoporosis and bone alterations are highly prevalent. The relationship between 25(OH)D and iron deficiencies with osteoporosis is unknown up to date. This review presents the current knowledge on nutritional iron and vitamin D deficiencies in bone remodeling, and discuss the link between iron and bone metabolism among postmenopausal women. Finally, it is hypothesized that chronic iron and vitamin D deficiencies induces bone resorption and risk of osteoporosis, thus complete recovery from anemia and its prevention should be promoted in order to improve quality of life including bone health. Several mechanisms are implicated; hence, further investigation on the possible impact of iron and vitamin D deficiencies on the development of osteoporosis is needed.
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Affiliation(s)
- Nasser M Al-Daghri
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University Riyadh 11451, Saudi Arabia
| | - Sobhy Yakout
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University Riyadh 11451, Saudi Arabia
| | - Afnan Ghaleb
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University Riyadh 11451, Saudi Arabia
| | - Syed Danish Hussain
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University Riyadh 11451, Saudi Arabia
| | - Shaun Sabico
- Chair for Biomarkers of Chronic Diseases, Biochemistry Department, College of Science, King Saud University Riyadh 11451, Saudi Arabia
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Kumar P, Liu Y, Shen Y, Maher JJ, Cingolani F, Czaja MJ. Mouse liver injury induces hepatic macrophage FGF23 production. PLoS One 2022; 17:e0264743. [PMID: 35231062 PMCID: PMC8887750 DOI: 10.1371/journal.pone.0264743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 02/15/2022] [Indexed: 01/22/2023] Open
Abstract
Fibroblast growth factor 23 (FGF23) is a bone marrow cell produced hormone that functions in the intestine and kidney to regulate phosphate homeostasis. Increased serum FGF23 is a well-established predictor of mortality in renal disease, but recent findings linking increased levels to hepatic and cardiac diseases have suggested that other organs are sources of FGF23 or targets of its effects. The potential ability of the liver to produce FGF23 in response to hepatocellular injury was therefore examined. Very low levels of Fgf23 mRNA and FGF23 protein were detected in normal mouse liver, but the amounts increased markedly during acute liver injury from the hepatotoxin carbon tetrachloride. Serum levels of intact FGF23 were elevated during liver injury from carbon tetrachloride. Chronic liver injury induced by a high fat diet or elevated bile acids also increased hepatic FGF23 levels. Stimulation of toll-like receptor (TLR) 4-driven inflammation by gut-derived lipopolysaccharide (LPS) underlies many forms of liver injury, and LPS induced Fgf23 in the liver as well as in other organs. The LPS-inducible cytokines IL-1β and TNF increased hepatic Fgf23 expression as did a TLR2 agonist Pam2CSK3. Analysis of Fgf23 expression and FGF23 secretion in different hepatic cell types involved in liver injury identified the resident liver macrophage or Kupffer cell as a source of hepatic FGF23. LPS and cytokines selectively induced the hormone in these cells but not in hepatocytes or hepatic stellate cells. FGF23 failed to exert any autocrine effect on the inflammatory state of Kupffer cells but did trigger proinflammatory activation of hepatocytes. During liver injury inflammatory factors induce Kupffer cell production of FGF23 that may have a paracrine proinflammatory effect on hepatocytes. Liver-produced FGF23 may have systemic hormonal effects as well that influence diseases in in other organs.
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Affiliation(s)
- Pradeep Kumar
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Yunshan Liu
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Yang Shen
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Jacquelyn J. Maher
- Department of Medicine and Liver Center, University of California, San Francisco, San Francisco, California, United States of America
| | - Francesca Cingolani
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Mark J. Czaja
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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Takashi Y, Kawanami D. The Role of Bone-Derived Hormones in Glucose Metabolism, Diabetic Kidney Disease, and Cardiovascular Disorders. Int J Mol Sci 2022; 23:ijms23042376. [PMID: 35216490 PMCID: PMC8879859 DOI: 10.3390/ijms23042376] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/16/2022] [Accepted: 02/19/2022] [Indexed: 12/19/2022] Open
Abstract
Bone contributes to supporting the body, protecting the central nervous system and other organs, hematopoiesis, the regulation of mineral metabolism (mainly calcium and phosphate), and assists in respiration. Bone has many functions in the body. Recently, it was revealed that bone also works as an endocrine organ and secretes several systemic humoral factors, including fibroblast growth factor 23 (FGF23), osteocalcin (OC), sclerostin, and lipocalin 2. Bone can communicate with other organs via these hormones. In particular, it has been reported that these bone-derived hormones are involved in glucose metabolism and diabetic complications. Some functions of these bone-derived hormones can become useful biomarkers that predict the incidence of diabetes and the progression of diabetic complications. Furthermore, other functions are considered to be targets for the prevention or treatment of diabetes and its complications. As is well known, diabetes is now a worldwide health problem, and many efforts have been made to treat diabetes. Thus, further investigations of the endocrine system through bone-derived hormones may provide us with new perspectives on the prediction, prevention, and treatment of diabetes. In this review, we summarize the role of bone-derived hormones in glucose metabolism, diabetic kidney disease, and cardiovascular disorders.
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Kato H, Hidaka N, Koga M, Ogawa N, Takahashi S, Miyazaki H, Nangaku M, Makita N, Ito N. Performance evaluation of the new chemiluminescent intact FGF23 assay relative to the existing assay system. J Bone Miner Metab 2022; 40:101-108. [PMID: 34351500 DOI: 10.1007/s00774-021-01258-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 07/29/2021] [Indexed: 11/25/2022]
Abstract
INTRODUCTION This study assessed the performance of a new fully automated immunoassay for fibroblast growth factor (FGF) 23 (Determinar CL FGF23 CL) among healthy individuals and those with chronic hypophosphatemia compared with the previous assay (Kainos FGF23 KI). MATERIALS AND METHODS A total of 380 serum samples from healthy participants were collected to determine the reference range of FGF23 levels with CL. A total of 200 serum samples from 22 hypophosphatemic patients were collected simultaneously to compare the difference in FGF23 levels between CL and KI. The Mann-Whitney U test and linear regression analysis were adopted to assess the differences and linearity between the two assays. RESULTS The median FGF23 levels among healthy individuals was 31.7 (interquartile: 26.4-37.5) pg/mL. When the reference range was calculated as the mean ± 2 standard deviation (2SD), it was 16.1-49.3 pg/mL. A total of 363 individuals (96%) among normal cases fell in this range. Among 200 samples from patients with chronic hypophosphatemic disorder, the median FGF23 levels analyzed by CL and KI were 123.0 (90.2-237.7) and 172.5 (115.8-290.7) pg/mL. KI yielded significantly higher FGF23 values than CL (p < 0.001). A linear regression model revealed the correlation between KI (x) and CL (y), which had a slope of 0.76 with a y-intercept of -0.32 and high linearity (R2 = 0.99). CONCLUSION The new measurement kit yielded lower FGF23 values when compared with the previous assay. Clinicians should consider this discrepancy when they assay intact FGF23 values with CL.
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Affiliation(s)
- Hajime Kato
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Naoko Hidaka
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Minae Koga
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Noriyuki Ogawa
- Minaris Medical Co., Ltd., 600-1, Minami-ishiki, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-0932, Japan
| | - Shichihiro Takahashi
- Minaris Medical Co., Ltd., 600-1, Minami-ishiki, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-0932, Japan
| | - Hiromi Miyazaki
- Minaris Medical Co., Ltd., 600-1, Minami-ishiki, Nagaizumi-cho, Sunto-gun, Shizuoka, 411-0932, Japan
| | - Masaomi Nangaku
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Noriko Makita
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Nobuaki Ito
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
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Yamazaki M, Michigami T. Osteocytes and the pathogenesis of hypophosphatemic rickets. Front Endocrinol (Lausanne) 2022; 13:1005189. [PMID: 36246908 PMCID: PMC9556901 DOI: 10.3389/fendo.2022.1005189] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 09/15/2022] [Indexed: 11/13/2022] Open
Abstract
Since phosphorus is a component of hydroxyapatite, its prolonged deprivation affects bone mineralization. Fibroblast growth factor 23 (FGF23) is essential for maintaining phosphate homeostasis and is mainly produced by osteocytes. FGF23 increases the excretion of inorganic phosphate (Pi) and decreases the production of 1,25-dihydroxyvitamin D in the kidneys. Osteocytes are cells of osteoblastic lineage that have undergone terminal differentiation and become embedded in mineralized bone matrix. Osteocytes express FGF23 and other multiple genes responsible for hereditary hypophosphatemic rickets, which include phosphate-regulating gene homologous to endopeptidase on X chromosome (PHEX), dentin matrix protein 1 (DMP1), and family with sequence similarity 20, member C (FAM20C). Since inactivating mutations in PHEX, DMP1, and FAM20C boost the production of FGF23, these molecules might be considered as local negative regulators of FGF23. Mouse studies have suggested that enhanced FGF receptor (FGFR) signaling is involved in the overproduction of FGF23 in PHEX-deficient X-linked hypophosphatemic rickets (XLH) and DMP1-deficient autosomal recessive hypophosphatemic rickets type 1. Since FGFR is involved in the transduction of signals evoked by extracellular Pi, Pi sensing in osteocytes may be abnormal in these diseases. Serum levels of sclerostin, an inhibitor Wnt/β-catenin signaling secreted by osteocytes, are increased in XLH patients, and mouse studies have suggested the potential of inhibiting sclerostin as a new therapeutic option for the disease. The elucidation of complex abnormalities in the osteocytes of FGF23-related hypophosphatemic diseases will provide a more detailed understanding of their pathogenesis and more effective treatments.
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Alber J, Freisinger P, Föller M. The synthesis of fibroblast growth factor 23 is upregulated by homocysteine in UMR106 osteoblast-like cells. Nutrition 2021; 96:111573. [PMID: 35091320 DOI: 10.1016/j.nut.2021.111573] [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] [Received: 09/28/2021] [Revised: 12/06/2021] [Accepted: 12/13/2021] [Indexed: 10/19/2022]
Abstract
OBJECTIVES Fibroblast growth factor 23 (FGF23) controls the production and degradation of biologically active vitamin D, 1,25(OH)2D3, and phosphate reabsorption in the kidney as a hormone synthesized by bone cells. Additional paracrine effects in other organs exist as well. As a biomarker, the FGF23 plasma concentration increases in renal and cardiovascular diseases, and is correlated with outcome. The regulation of FGF23 is incompletely understood and dependent on several factors, including oxidative stress. L-homocysteine is an amino acid produced in methionine metabolism, and can be converted into further metabolites depending on the availability of vitamin B. Hyperhomocysteinemia is a potential cardiovascular risk factor. Our study aimed to explore whether homocysteine impacts FGF23 synthesis. METHODS Experiments were performed in UMR106 osteoblast-like cells. Fgf23 gene expression and FGF23 protein concentration were measured by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Oxidative stress was determined by 2',7'-dichlorofluorescein diacetate fluorescence. RESULTS Homocysteine dose-dependently upregulated Fgf23 gene expression and protein synthesis. Moreover, homocysteine imposed oxidative stress on UMR106 cells. The effect of homocysteine on Fgf23 was abrogated by antioxidant ascorbic acid. CONCLUSIONS Homocysteine is a potent stimulator of FGF23 production, an effect at least in part mediated by oxidative stress. The homocysteine-dependent upregulation of FGF23 presumably contributes to its role as a cardiovascular risk factor.
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Affiliation(s)
- Jana Alber
- University of Hohenheim, Department of Physiology, Stuttgart, Germany
| | - Peter Freisinger
- Kreiskliniken Reutlingen, Department of Pediatrics, Reutlingen, Germany
| | - Michael Föller
- University of Hohenheim, Department of Physiology, Stuttgart, Germany.
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Induction of FGF23-related hypophosphatemic osteomalacia by alcohol consumption. Bone Rep 2021; 15:101144. [PMID: 34901334 PMCID: PMC8640868 DOI: 10.1016/j.bonr.2021.101144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/07/2021] [Accepted: 10/12/2021] [Indexed: 02/03/2023] Open
Abstract
Context Fibroblast growth factor (FGF) 23 is a hormone that regulates serum phosphate levels, the excess action of which causes chronic hypophosphatemic rickets/osteomalacia. To date, there are only two identified causes of acquired FGF23-related hypophosphatemic osteomalacia: tumor-induced osteomalacia (TIO) and osteomalacia induced by the intravenous infusion of some forms of iron preparations. In the current study, two cases of FGF23-related hypophosphatemia probably induced by chronic alcohol consumption were first introduced. Case description Case 1 and case 2 had been drinking high amounts of alcohol for more than twenty years until they were admitted to the hospital. Case 1 was a 43-year-old man with progressive worsening multiple pains and muscle weakness who exhibited chronic hypophosphatemia with increased intact FGF23 levels. A week after admission, the serum phosphate level recovered to the reference range, and the intact FGF23 level declined. Case 1 resumed drinking after discharge, and hypophosphatemia concomitant with high intact FGF23 levels recurred. The alleviation of FGF23-related hypophosphatemia was observed each time he temporarily abstained from drinking for a short period. Case 2 was a 60-year-old man with recurrent fractures and exacerbation of pain in multiple joints who also exhibited hypophosphatemia with increased intact FGF23 levels. After admission, the serum phosphate level gradually increased to the lower limit of the normal range. The intact FGF23 level decreased, but it was still higher than 30 pg/ml, and causative FGF23-producing tumors were not identified even with thorough examinations, including somatostatin receptor scintigraphy, fluorine-18-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG-PET/CT) and systemic venous FGF23 sampling. He completely abstained from alcohol after discharge. Along with the serum phosphate level, intact FGF23 was subsequently decreased and had been normalized for 5 months. Both patients had no genetic mutation related to hereditary FGF23-related hypophosphatemic rickets/osteomalacia, including autosomal dominant hypophosphatemic rickets/osteomalacia (ADHR). Conclusion Two cases of FGF23-related hypophosphatemia probably induced by alcohol were first introduced in this study. Identifying this reversible condition among acquired FGF23-related hypophosphatemic osteomalacia is critical to obtain better patient outcomes and save medical resources. This condition is similar to iron infusion-induced FGF23-related hypophosphatemia in terms of the dysregulation of FGF23 due to exogenous factors. Future research to elucidate the precise mechanism of these conditions is warranted. Two adults with acquired FGF23-related hypophosphatemic osteomalacia were studied. Tumor-induced osteomalacia was suspected initially, but no tumor was identified. Cessation of alcohol led to recovery from FGF23-related hypophosphatemia. Alcohol is a well-recognized cause of hypophosphatemia, but osteomalacia is uncommon. Alcohol-induced FGF23-related osteomalacia is a totally new and distinct phenomenon.
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Abstract
PURPOSE OF REVIEW Fibroblast growth factor 23 (FGF23) is a bone- and bone marrow-derived hormone that is critical to maintain phosphate homeostasis. The principal actions of FGF23 are to reduce serum phosphate levels by decreasing kidney phosphate reabsorption and 1,25-dihydroxyvitamin D synthesis. FGF23 deficiency causes hyperphosphatemia and ectopic calcifications, while FGF23 excess causes hypophosphatemia and skeletal defects. Excess FGF23 also correlates with kidney disease, where it is associated with increased morbidity and mortality. Accordingly, FGF23 levels are tightly regulated, but the mechanisms remain incompletely understood. RECENT FINDINGS In addition to bone mineral factors, additional factors including iron, erythropoietin, inflammation, energy, and metabolism regulate FGF23. All these factors affect Fgf23 expression, while some also regulate FGF23 protein cleavage. Conversely, FGF23 may have a functional role in regulating these biologic processes. Understanding the bi-directional relationship between FGF23 and non-bone mineral factors is providing new insights into FGF23 regulation and function.
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Affiliation(s)
- Petra Simic
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
| | - Jodie L Babitt
- Nephrology Division, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
- Program in Membrane Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
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Limm-Chan B, Wesseling-Perry K, Pearl MH, Jung G, Tsai-Chambers E, Weng PL, Hanudel MR. Associations among erythropoietic, iron-related, and FGF23 parameters in pediatric kidney transplant recipients. Pediatr Nephrol 2021; 36:3241-3249. [PMID: 33903951 PMCID: PMC8448905 DOI: 10.1007/s00467-021-05081-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/16/2021] [Accepted: 04/06/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND In pediatric kidney transplant recipients, anemia is common and oftentimes multifactorial. Hemoglobin concentrations may be affected by traditional factors, such as kidney function and iron status, as well as novel parameters, such as fibroblast growth factor 23 (FGF23). METHODS Here, we evaluated associations among erythropoietic, iron-related, and FGF23 parameters in a cohort of pediatric kidney transplant recipients, hypothesizing that multiple factors are associated with hemoglobin concentrations. RESULTS In a cross-sectional analysis of 59 pediatric kidney transplant recipients (median (interquartile range) age 16.3 (13.5, 18.6) years, median estimated glomerular filtration rate (eGFR) 67 (54, 87) ml/min/1.73 m2), the median age-related hemoglobin standard deviation score (SDS) was -2.1 (-3.3, -1.1). Hemoglobin SDS was positively associated with eGFR and calcium, and was inversely associated with erythropoietin (EPO), mycophenolate dose, and total, but not intact, FGF23. In multivariable analysis, total FGF23 remained inversely associated with hemoglobin SDS, independent of eGFR, iron parameters, EPO, and inflammatory markers, suggesting a novel FGF23-hemoglobin association in pediatric kidney transplant patients. In a subset of patients with repeat measurements, only delta hepcidin was inversely associated with delta hemoglobin SDS. Also, delta EPO positively correlated with delta erythroferrone (ERFE), and delta ERFE inversely correlated with delta hepcidin, suggesting a possible physiologic role for the EPO-ERFE-hepcidin axis in the setting of chronic kidney disease (CKD). CONCLUSION Our study provides further insight into factors potentially associated with erythropoiesis in pediatric kidney transplant recipients. A higher resolution version of the Graphical abstract is available as Supplementary information.
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Affiliation(s)
- Blair Limm-Chan
- Department of Pediatrics, Division of Pediatric Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA
| | - Katherine Wesseling-Perry
- Department of Pediatrics, Division of Pediatric Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA
| | - Meghan H Pearl
- Department of Pediatrics, Division of Pediatric Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA
| | - Grace Jung
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095-1752, USA
| | | | - Patricia L Weng
- Department of Pediatrics, Division of Pediatric Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA
| | - Mark R Hanudel
- Department of Pediatrics, Division of Pediatric Nephrology, David Geffen School of Medicine at UCLA, 10833 Le Conte Avenue, MDCC A2-383, Los Angeles, CA, 90095-1752, USA.
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Dahir K, Zanchetta MB, Stanciu I, Robinson C, Lee JY, Dhaliwal R, Charles J, Civitelli R, Roberts MS, Krolczyk S, Weber T. Diagnosis and Management of Tumor-induced Osteomalacia: Perspectives From Clinical Experience. J Endocr Soc 2021; 5:bvab099. [PMID: 34286168 PMCID: PMC8282217 DOI: 10.1210/jendso/bvab099] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Indexed: 01/12/2023] Open
Abstract
Purpose Tumor-induced osteomalacia (TIO) is a rare paraneoplastic syndrome of abnormal phosphate and vitamin D metabolism caused by typically small endocrine tumors that secrete fibroblast growth factor 23 (FGF23). TIO is characterized clinically by progressive musculoskeletal pain, fatigue, proximal muscle weakness, and multiple fractures, leading to long-term disability. Misdiagnosis and delayed diagnosis are common because of the nonspecific symptoms, and several years may elapse before patients receive an accurate diagnosis and appropriate treatment. Thus, it is vital that awareness of the appropriate recognition and management of TIO is increased among healthcare professionals who may encounter patients with suspected TIO. Methods A roundtable meeting was held on 10 January 2020 in Dallas, TX, USA, to gather perspectives on the diagnosis and treatment of TIO. The following topics were considered: clinical presentation, patient history, differential diagnosis, laboratory assessment, imaging, venous sampling, and treatment. Results This report provides a summary of our collective experiences in the management of TIO. Main conclusions Laboratory tests are mandatory to expedite TIO diagnosis and should include measurement of fasting serum phosphorus, renal phosphate reabsorption, serum 1,25-dihydroxyvitamin D, and serum FGF23 levels. Functional and anatomical imaging are essential to locate the FGF23-secreting tumor(s) causing TIO. Surgical resection is often a curative treatment when the tumor can be localized; however, better management of patients who cannot be operated on with targeted therapies is needed. Further efforts to increase awareness of TIO within the medical community, and education on recommended diagnostic and treatment pathways are required to improve the management of this debilitating disease.
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Affiliation(s)
- Kathryn Dahir
- Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | | | - Irinel Stanciu
- Panorama Orthopedics and Spine Center, Golden, CO 80401, USA
| | - Cemre Robinson
- Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Janet Y Lee
- University of California, San Francisco, CA 94143, USA
| | - Ruban Dhaliwal
- State University of New York Upstate Medical University, Syracuse, NY 13210, USA
| | - Julia Charles
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | | | - Stan Krolczyk
- Ultragenyx Pharmaceutical Inc., Novato, CA 94949, USA
| | - Thomas Weber
- Duke University School of Medicine, Durham, NC 27710, USA
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Rickets, elevated fibroblast growth factor-23 and mild anemia: Answers. Pediatr Nephrol 2021; 36:2301-2304. [PMID: 33646398 DOI: 10.1007/s00467-021-05012-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 11/27/2022]
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Ito N, Prideaux M, Wijenayaka AR, Yang D, Ormsby RT, Bonewald LF, Atkins GJ. Sclerostin Directly Stimulates Osteocyte Synthesis of Fibroblast Growth Factor-23. Calcif Tissue Int 2021; 109:66-76. [PMID: 33616712 DOI: 10.1007/s00223-021-00823-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 02/05/2021] [Indexed: 12/16/2022]
Abstract
Osteocyte produced fibroblast growth factor 23 (FGF23) is the key regulator of serum phosphate (Pi) homeostasis. The interplay between parathyroid hormone (PTH), FGF23 and other proteins that regulate FGF23 production and serum Pi levels is complex and incompletely characterised. Evidence suggests that the protein product of the SOST gene, sclerostin (SCL), also a PTH target and also produced by osteocytes, plays a role in FGF23 expression, however the mechanism for this effect is unclear. Part of the problem of understanding the interplay of these mediators is the complex multi-organ system that achieves Pi homeostasis in vivo. In the current study, we sought to address this using a cell line model of the osteocyte, IDG-SW3, known to express FGF23 at both the mRNA and protein levels. In cultures of differentiated IDG-SW3 cells, both PTH1-34 and recombinant human (rh) SCL remarkably induced Fgf23 mRNA expression dose-dependently within 3 h. Both rhPTH1-34 and rhSCL also strongly induced C-terminal FGF23 protein secretion. Secreted intact FGF23 levels remained unchanged, consistent with constitutive post-translational cleavage of FGF23 in this cell model. Both rhPTH1-34 and rhSCL treatments significantly suppressed mRNA levels of Phex, Dmp1 and Enpp1 mRNA, encoding putative negative regulators of FGF23 levels, and induced Galnt3 mRNA expression, encoding N-acetylgalactosaminyl-transferase 3 (GalNAc-T3), which protects FGF23 from furin-like proprotein convertase-mediated cleavage. The effect of both rhPTH1-34 and rhSCL was antagonised by pre-treatment with the NF-κβ signalling inhibitors, BAY11 and TPCK. RhSCL also stimulated FGF23 mRNA expression in ex vivo cultures of human bone. These findings provide evidence for the direct regulation of FGF23 expression by sclerostin. Locally expressed sclerostin via the induction of FGF23 in osteocytes thus has the potential to contribute to the regulation of Pi homeostasis.
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Affiliation(s)
- Nobuaki Ito
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, The University of Adelaide, Adelaide, SA, 5000, Australia
- Division of Nephrology and Endocrinology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | - Matthew Prideaux
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, The University of Adelaide, Adelaide, SA, 5000, Australia
- School of Medicine, Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA
| | - Asiri R Wijenayaka
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, The University of Adelaide, Adelaide, SA, 5000, Australia
| | - Dongqing Yang
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, The University of Adelaide, Adelaide, SA, 5000, Australia
| | - Renee T Ormsby
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, The University of Adelaide, Adelaide, SA, 5000, Australia
- Brigham and Women's Hospital, Boston, MA, USA
| | - Lynda F Bonewald
- School of Medicine, Indiana Center for Musculoskeletal Health, Indiana University, Indianapolis, IN, 46202, USA
| | - Gerald J Atkins
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic & Trauma Research, The University of Adelaide, Adelaide, SA, 5000, Australia.
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Rickets in Children: An Update. Biomedicines 2021; 9:biomedicines9070738. [PMID: 34199067 PMCID: PMC8301330 DOI: 10.3390/biomedicines9070738] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/15/2021] [Accepted: 06/24/2021] [Indexed: 12/16/2022] Open
Abstract
Rickets refers to a deficient mineralization of the growth plate cartilage, predominantly affecting longer bones. Despite the fact that preventive measures are available, it is still a common disease worldwide; nutritional rickets, due to vitamin D deficiency or dietary calcium inadequate intake, remains the most common form. Medical history, physical examination, radiologic features and biochemical tests are essential for diagnosis. Although recent studies suggest hypophosphatemia as the leading alteration, rickets is classically divided into two categories: calcipenic rickets and phosphopenic rickets. Knowledge of this categorization and of respective clinical and laboratory features is essential for rapid diagnosis and correct management. The aim of this review is to analyze the epidemiological, pathogenetic, clinical, and therapeutic aspects of the different forms of rickets, describing the novelties on this “long-lived” disease.
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48
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Cariati I, Bonanni R, Onorato F, Mastrogregori A, Rossi D, Iundusi R, Gasbarra E, Tancredi V, Tarantino U. Role of Physical Activity in Bone-Muscle Crosstalk: Biological Aspects and Clinical Implications. J Funct Morphol Kinesiol 2021; 6:55. [PMID: 34205747 PMCID: PMC8293201 DOI: 10.3390/jfmk6020055] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 02/06/2023] Open
Abstract
Bone and muscle tissues influence each other through the integration of mechanical and biochemical signals, giving rise to bone-muscle crosstalk. They are also known to secrete osteokines, myokines, and cytokines into the circulation, influencing the biological and pathological activities in local and distant organs and cells. In this regard, even osteoporosis and sarcopenia, which were initially thought to be two independent diseases, have recently been defined under the term "osteosarcopenia", to indicate a synergistic condition of low bone mass with muscle atrophy and hypofunction. Undoubtedly, osteosarcopenia is a major public health concern, being associated with high rates of morbidity and mortality. The best current defence against osteosarcopenia is prevention based on a healthy lifestyle and regular exercise. The most appropriate type, intensity, duration, and frequency of exercise to positively influence osteosarcopenia are not yet known. However, combined programmes of progressive resistance exercises, weight-bearing impact exercises, and challenging balance/mobility activities currently appear to be the most effective in optimising musculoskeletal health and function. Based on this evidence, the aim of our review was to summarize the current knowledge about the role of exercise in bone-muscle crosstalk, highlighting how it may represent an effective alternative strategy to prevent and/or counteract the onset of osteosarcopenia.
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Affiliation(s)
- Ida Cariati
- PhD in Medical-Surgical Biotechnologies and Translational Medicine, “Tor Vergata” University of Rome, Via Montpellier 1, 00133 Rome, Italy;
- Department of Clinical Sciences and Translational Medicine, “Tor Vergata” University of Rome, Via Montpellier 1, 00133 Rome, Italy
| | - Roberto Bonanni
- Department of Systems Medicine, “Tor Vergata” University of Rome, Via Montpellier 1, 00133 Rome, Italy; (R.B.); (V.T.)
| | - Federica Onorato
- Department of Orthopaedics and Traumatology, “Policlinico Tor Vergata” Foundation, Viale Oxford 81, 00133 Rome, Italy; (F.O.); (A.M.); (D.R.); (R.I.); (E.G.)
| | - Ambra Mastrogregori
- Department of Orthopaedics and Traumatology, “Policlinico Tor Vergata” Foundation, Viale Oxford 81, 00133 Rome, Italy; (F.O.); (A.M.); (D.R.); (R.I.); (E.G.)
| | - Danilo Rossi
- Department of Orthopaedics and Traumatology, “Policlinico Tor Vergata” Foundation, Viale Oxford 81, 00133 Rome, Italy; (F.O.); (A.M.); (D.R.); (R.I.); (E.G.)
| | - Riccardo Iundusi
- Department of Orthopaedics and Traumatology, “Policlinico Tor Vergata” Foundation, Viale Oxford 81, 00133 Rome, Italy; (F.O.); (A.M.); (D.R.); (R.I.); (E.G.)
| | - Elena Gasbarra
- Department of Orthopaedics and Traumatology, “Policlinico Tor Vergata” Foundation, Viale Oxford 81, 00133 Rome, Italy; (F.O.); (A.M.); (D.R.); (R.I.); (E.G.)
| | - Virginia Tancredi
- Department of Systems Medicine, “Tor Vergata” University of Rome, Via Montpellier 1, 00133 Rome, Italy; (R.B.); (V.T.)
- Centre of Space Bio-Medicine, “Tor Vergata” University of Rome, Via Montpellier 1, 00133 Rome, Italy
| | - Umberto Tarantino
- Department of Clinical Sciences and Translational Medicine, “Tor Vergata” University of Rome, Via Montpellier 1, 00133 Rome, Italy
- Department of Orthopaedics and Traumatology, “Policlinico Tor Vergata” Foundation, Viale Oxford 81, 00133 Rome, Italy; (F.O.); (A.M.); (D.R.); (R.I.); (E.G.)
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Noonan ML, Ni P, Agoro R, Sacks SA, Swallow EA, Wheeler JA, Clinkenbeard EL, Capitano ML, Prideaux M, Atkins GJ, Thompson WR, Allen MR, Broxmeyer HE, White KE. The HIF-PHI BAY 85-3934 (Molidustat) Improves Anemia and Is Associated With Reduced Levels of Circulating FGF23 in a CKD Mouse Model. J Bone Miner Res 2021; 36:1117-1130. [PMID: 33592127 PMCID: PMC8255270 DOI: 10.1002/jbmr.4272] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 02/01/2021] [Accepted: 02/10/2021] [Indexed: 12/15/2022]
Abstract
Fibroblast growth factor-23 (FGF23) is a critical factor in chronic kidney disease (CKD), with elevated levels causing alterations in mineral metabolism and increased odds for mortality. Patients with CKD develop anemia as the kidneys progressively lose the ability to produce erythropoietin (EPO). Anemia is a potent driver of FGF23 secretion; therefore, a hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) currently in clinical trials to elevate endogenous EPO to resolve anemia was tested for effects on iron utilization and FGF23-related parameters in a CKD mouse model. Mice were fed either a casein control diet or an adenine-containing diet to induce CKD. The CKD mice had markedly elevated iFGF23 and blood urea nitrogen (BUN), hyperphosphatemia, and anemia. Cohorts of mice were then treated with a patient-equivalent dose of BAY 85-3934 (BAY; Molidustat), which elevated EPO and completely resolved aberrant complete blood counts (CBCs) in the CKD mice. iFGF23 was elevated in vehicle-treated CKD mice (120-fold), whereas circulating iFGF23 was significantly attenuated (>60%) in the BAY-treated CKD mice. The BAY-treated mice with CKD also had reduced BUN, but there was no effect on renal vitamin D metabolic enzyme expression. Consistent with increased EPO, bone marrow Erfe, Transferrin receptor (Tfrc), and EpoR mRNAs were increased in BAY-treated CKD mice, and in vitro hypoxic marrow cultures increased FGF23 with direct EPO treatment. Liver Bmp-6 and hepcidin expression were downregulated in all BAY-treated groups. Femur trabecular parameters and cortical porosity were not worsened with BAY administration. In vitro, differentiated osteocyte-like cells exposed to an iron chelator to simulate iron depletion/hypoxia increased FGF23; repletion with holo-transferrin completely suppressed FGF23 and normalized Tfrc1. Collectively, these results support that resolving anemia using a HIF-PHI during CKD was associated with lower BUN and reduced FGF23, potentially through direct restoration of iron utilization, thus providing modifiable outcomes beyond improving anemia for this patient population. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Megan L Noonan
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Pu Ni
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Rafiou Agoro
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Spencer A Sacks
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, IN
| | - Elizabeth A Swallow
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, IN
| | - Jonathan A Wheeler
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Erica L Clinkenbeard
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Maegan L Capitano
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN
| | - Matthew Prideaux
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, IN
| | - Gerald J Atkins
- Centre for Orthopaedic and Trauma Research, The University of Adelaide, Adelaide, Australia
| | - William R Thompson
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, IN
| | - Matthew R Allen
- Department of Anatomy, Cell Biology, and Physiology, Indiana University School of Medicine, Indianapolis, IN
- Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, IN
| | - Hal E Broxmeyer
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN
| | - Kenneth E White
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
- Department of Medicine, Division of Nephrology, Indiana University School of Medicine, Indianapolis, IN
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50
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Daude S, Quinaux T, Collet-Fenêtrier B, Silve C, Okamba P, Tubail Z, Savenkoff B. [A complex case of renal phosphate wasting…]. Nephrol Ther 2021; 17:466-472. [PMID: 33994136 DOI: 10.1016/j.nephro.2020.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 04/11/2020] [Accepted: 05/04/2020] [Indexed: 11/16/2022]
Abstract
We describe here the case report of a young man of 34-years old suffering from a haemorrhagic rectocolitis and presenting with marked hypophosphatemia secondary to an infusion of ferric-carboxymaltose. The renal phosphate wasting was asserted by a very low renal maximal reabsorption rate of phosphate associated with a high plasma FGF-23 level. Three months later we explored the patient and his father since we learnt that both of them had suffered from kidney stones for years with marked hypercalciuria. Kidney stones were composed of weddellite and carbapatite. We suspected a familial phosphate renal wasting syndrome but however no mutation of the renal phosphate carriers could be identified.
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Affiliation(s)
- Sébastien Daude
- Service d'hépato-gastro-entérologie, CHRU de Nancy, 1, rue du Morvan, 54500 Vandœuvre-lès-Nancy, France
| | - Thomas Quinaux
- Service de néphrologie, dialyse et aphérèse thérapeutique, hôpital de Mercy CS45001, CHR de Metz-Thionville, 1, allée du Château, 57085 Metz cedex 03, France
| | - Benjamin Collet-Fenêtrier
- Service d'hépato-gastro-entérologie, hôpital de Mercy CS45001, CHR de Metz-Thionville, 1, allée du Château, 57085 Metz cedex 03, France
| | - Caroline Silve
- Laboratoire de biochimie et génétique moléculaire, hôpital Cochin, 27, rue du Faubourg-Saint-Jacques, 75014 Paris, France
| | - Patricia Okamba
- Laboratoire de biochimie et d'immunologie, CHR de Metz Thionville, Hôpital de Mercy CS45001, 1, allée du Château, 57085 Metz cedex 03, France
| | - Zead Tubail
- Service de néphrologie, dialyse et aphérèse thérapeutique, hôpital de Mercy CS45001, CHR de Metz-Thionville, 1, allée du Château, 57085 Metz cedex 03, France
| | - Benjamin Savenkoff
- Service de néphrologie, dialyse et aphérèse thérapeutique, hôpital de Mercy CS45001, CHR de Metz-Thionville, 1, allée du Château, 57085 Metz cedex 03, France.
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