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Salles Rosa Neto N, Pereira RMR, Yuki EFN, Souza FHCD, Takayama L, Carneiro MIDS, Lima LGCAD, Ishy A, Elias AJR. Healing of tumor-induced osteomalacia as assessed by high-resolution peripheral quantitative computed tomography is not similar across the skeleton in the first years following complete tumor excision. Bone Rep 2024; 21:101758. [PMID: 38584681 PMCID: PMC10997823 DOI: 10.1016/j.bonr.2024.101758] [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: 11/23/2023] [Revised: 03/24/2024] [Accepted: 03/27/2024] [Indexed: 04/09/2024] Open
Abstract
Tumor-induced osteomalacia is caused by excessive fibroblast growth factor 23 production mainly from phosphaturic mesenchymal tumors. Surgical excision or tumor ablation are the preferred treatment. Information on bone microarchitecture parameters assessed by high-resolution peripheral quantitative computed tomography is limited. We report a woman with hypophosphatemic osteomalacia with generalized pain, weakness and recurrent fractures, and a large thoracic vertebral mass extending to the posterior mediastinum. Detailed radiologic and histopathologic evaluation revealed a phosphaturic mesenchymal tumor. Two surgeries were necessary for complete removal of the mass. Clinical symptoms improved after attaining normophosphatemia. Four-year post-surgical HR-pQCT parameters, compared to baseline, showed in the left distal radius, stable trabecular and cortical volumetric bone mineral density although below reference range. There was stability of trabecular number and thickness. Both stiffness and failure load decreased. A shift in cortical parameters was noted in year 2. In the left distal tibia, trabecular volumetric bone mineral density decreased whereas cortical volumetric bone mineral density markedly increased, as did cortical area. There was stability in the trabecular number and thickness. Both stiffness and failure load improved. Findings from HR-pQCT measurements in this patient disclosed that the healing of osteomalacia is not similar across the peripheral skeletal sites in the first years following tumor removal. Results contrasted low but stable volumetric bone mineral density in the distal radius with increase in the distal tibia at the expense of cortical bone. Our report helps further delineate the pattern of bone healing after treatment of this rare bone disorder.
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Affiliation(s)
- Nilton Salles Rosa Neto
- Center for Rare and Immune Disorders, Hospital Nove de Julho, São Paulo, Brazil
- Universidade Santo Amaro, São Paulo, Brazil
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Vollmer S, Olsson K. Tumour-induced osteomalacia: the long road to diagnosis and recovery. BMJ Case Rep 2024; 17:e258858. [PMID: 38697682 PMCID: PMC11085914 DOI: 10.1136/bcr-2023-258858] [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] [Indexed: 05/05/2024] Open
Abstract
Tumour-induced osteomalacia is caused by tumorous production of fibroblast growth factor 23 (FGF23) leading to urinary phosphate wasting, hypophosphataemia and decreased vitamin D activation. The resulting osteomalacia presents with muscle weakness and bone pain but progresses to multiple pathological fractures. Patients often remain undiagnosed for years with severe physical, psychological and economic ramifications. A young woman presented with multiple spontaneous fractures including bilateral femoral fractures. Laboratory tests revealed severe hypophosphataemia, elevated bone turnover markers and low to normal calcium and 25-hydroxy-vitamin D levels. Treatment with phosphate, alfalcalcidol, calcium and magnesium was initiated. 68Gallium-DOTATOC positron emission tomography imaging revealed a mass in the right foot and venous sampling of FGF23 from all extremities confirmed this tumour as the culprit. Biopsy and histology were consistent with a phosphaturic mesenchymal tumour, which was surgically resected. Phosphate levels quickly normalised postoperatively but a long convalescence with hungry bone syndrome, fracture healing and physical therapy followed.
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Affiliation(s)
- Shobitha Vollmer
- Department of Endocrinology, Skane University Hospital, Lund, Sweden
| | - Karin Olsson
- Department of Endocrinology, Skane University Hospital, Lund, Sweden
- Department of Clinical Sciences, Lund University, Lund, Sweden
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Sawatsubashi S, Takashi Y, Endo I, Kondo T, Abe M, Matsumoto T, Fukumoto S. Familial cases with adult-onset FGF23-related hypophosphatemic osteomalacia -A PHEX 3'-UTR change as a possible cause. Bone 2024; 182:117057. [PMID: 38412893 DOI: 10.1016/j.bone.2024.117057] [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: 11/27/2023] [Revised: 02/04/2024] [Accepted: 02/21/2024] [Indexed: 02/29/2024]
Abstract
Excessive actions of FGF23 cause several kinds of hypophosphatemic rickets/osteomalacia. It is possible that there still remain unknown causes or mechanisms for FGF23-related hypophosphatemic diseases. We report two male cousins who had been suffering form FGF23-related hypophosphatemic osteomalacia. Sequencing of exons and exon-intron junctions of known causative genes for FGF23-related hypophosphatemic diseases and whole genome sequencing were conducted. Luciferase assay was used to evaluate the effect of a detected nucleotide change on mRNA stability. Two cousins showed hypophosphatemia with impaired proximal tubular phosphate reabsorption and high FGF23. Serum phosphate of their mothers was within the reference range. Exome sequencing of the proband detected no mutations. Whole genome sequencing of the patients and their mothers identified a nucleotide change in the 3'-UTR of phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX) gene (c.*1280_*1287dupGTGTGTGT) which is heterozygous in the mothers and hemizygous in the patients. While sixteen is the most prevalent number of GT repeats, this family had twenty repeats. Luciferase assay indicated that mRNA with 3'-UTR of PHEX with 20 GT repeats was more unstable than that with 16 repeats. Sequencing of exons and exon-intron junctions of known causative genes for FGF23-related hypophosphatemic diseases cannot identify all the genetic causes. Our results strongly suggest that changes of PHEX expression by a nucleotide change in the 3'-UTR is a novel mechanism of FGF23-related hypophosphatemic osteomalacia.
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Affiliation(s)
- Shun Sawatsubashi
- Department of Molecular Endocrinology, Fujii Memorial Institute of Medical Sciences, Tokushima University, Tokushima, Japan; Research and Innovation Liaison Office, Institute for Advanced Medical Sciences, Tokushima University, Tokushima, Japan
| | - Yuichi Takashi
- Department of Molecular Endocrinology, Fujii Memorial Institute of Medical Sciences, Tokushima University, Tokushima, Japan; Department of Endocrinology and Diabetes Mellitus, Fukuoka University School of Medicine, Fukuoka, Japan
| | - Itsuro Endo
- Department of Endocrinology, Metabolism and Hematology, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan
| | - Takeshi Kondo
- Department of Endocrinology, Metabolism and Hematology, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan
| | - Masahiro Abe
- Department of Endocrinology, Metabolism and Hematology, Tokushima University Graduate School of Medical Sciences, Tokushima, Japan
| | - Toshio Matsumoto
- Department of Molecular Endocrinology, Fujii Memorial Institute of Medical Sciences, Tokushima University, Tokushima, Japan
| | - Seiji Fukumoto
- Department of Molecular Endocrinology, Fujii Memorial Institute of Medical Sciences, Tokushima University, Tokushima, Japan; Department of Diabetes and Endocrinology, Tamaki-Aozora Hospital, Tokushima, Japan.
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Plotkin LI, Sanz N, Brun LR. Messages from the Mineral: How Bone Cells Communicate with Other Tissues. Calcif Tissue Int 2023; 113:39-47. [PMID: 37171619 PMCID: PMC10330496 DOI: 10.1007/s00223-023-01091-2] [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: 02/10/2023] [Accepted: 05/01/2023] [Indexed: 05/13/2023]
Abstract
Bone is a highly dynamic tissue, and the constant actions of bone-forming and bone-resorbing cells are responsible for attaining peak bone mass, maintaining bone mass in the adults, and the subsequent bone loss with aging and menopause, as well as skeletal complications of diseases and drug side-effects. It is now accepted that the generation and activity of bone-forming osteoblasts and bone-resorbing osteoclasts is modulated by osteocytes, osteoblast-derived cells embedded in the bone matrix. The interaction among bone cells occurs through direct contact and via secreted molecules. In addition to the regulation of bone cell function, molecules released by these cells are also able to reach the circulation and have effects in other tissues and organs in healthy individuals. Moreover, bone cell products have also been associated with the establishment or progression of diseases, including cancer and muscle weakness. In this review, we will discuss the role of bone as an endocrine organ, and the effect of selected, osteoblast-, osteocyte-, and osteoclast-secreted molecules on other tissues.
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Affiliation(s)
- Lilian I Plotkin
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Roudebush Veterans Administration Medical Center; and Indiana Center for Musculoskeletal Health, Indianapolis, IN, 46202, USA.
| | - Natasha Sanz
- Bone Biology Laboratory. School of Medicine, Rosario National University, Rosario, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rosario Santa Fe, Argentina
| | - Lucas R Brun
- Bone Biology Laboratory. School of Medicine, Rosario National University, Rosario, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rosario Santa Fe, Argentina
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Knowles HJ, Chanalaris A, Koutsikouni A, Cribbs AP, Grover LM, Hulley PA. Mature primary human osteocytes in mini organotypic cultures secrete FGF23 and PTH1-34-regulated sclerostin. Front Endocrinol (Lausanne) 2023; 14:1167734. [PMID: 37223031 PMCID: PMC10200954 DOI: 10.3389/fendo.2023.1167734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 04/03/2023] [Indexed: 05/25/2023] Open
Abstract
Introduction For decades, functional primary human osteocyte cultures have been crucially needed for understanding their role in bone anabolic processes and in endocrine phosphate regulation via the bone-kidney axis. Mature osteocyte proteins (sclerostin, DMP1, Phex and FGF23) play a key role in various systemic diseases and are targeted by successful bone anabolic drugs (anti-sclerostin antibody and teriparatide (PTH1-34)). However, cell lines available to study osteocytes produce very little sclerostin and low levels of mature osteocyte markers. We have developed a primary human 3D organotypic culture system that replicates the formation of mature osteocytes in bone. Methods Primary human osteoblasts were seeded in a fibrinogen / thrombin gel around 3D-printed hanging posts. Following contraction of the gel around the posts, cells were cultured in osteogenic media and conditioned media was collected for analysis of secreted markers of osteocyte formation. Results The organoids were viable for at least 6 months, allowing co-culture with different cell types and testing of bone anabolic drugs. Bulk RNAseq data displayed the developing marker trajectory of ossification and human primary osteocyte formation in vitro over an initial 8- week period. Vitamin D3 supplementation increased mineralization and sclerostin secretion, while hypoxia and PTH1-34 modulated sclerostin. Our culture system also secreted FGF23, enabling the future development of a bone-kidney-parathyroid-vascular multi-organoid or organ-on-a-chip system to study disease processes and drug effects using purely human cells. Discussion This 3D organotypic culture system provides a stable, long-lived, and regulated population of mature human primary osteocytes for a variety of research applications.
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Affiliation(s)
- Helen J. Knowles
- Botnar Institute for Musculoskeletal Sciences, Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
| | - Anastasios Chanalaris
- Botnar Institute for Musculoskeletal Sciences, Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
| | - Argyro Koutsikouni
- School of Biology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Adam P. Cribbs
- Botnar Institute for Musculoskeletal Sciences, Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
- Oxford Centre for Translational Myeloma Research, Botnar Institute for Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
| | - Liam M. Grover
- Healthcare Technologies Institute, School of Chemical Engineering, University of Birmingham, Birmingham, United Kingdom
| | - Philippa A. Hulley
- Botnar Institute for Musculoskeletal Sciences, Nuffield Department of Orthopaedics Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
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Treatment of X-Linked Hypophosphatemia in Children. ENDOCRINES 2022. [DOI: 10.3390/endocrines3030042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The conventional treatment for X-linked hypophosphatemia (XLH), consisting of phosphorus supplementation and a biologically active form of vitamin D (alfacalcidol or calcitriol), is used to treat rickets and leg deformities and promote growth. However, patients’ adult height often remains less than −2 SD. Moreover, adverse events, such as renal calcification and hyperparathyroidism, may occur. The main pathology in XLH is caused by excessive production of fibroblast growth factor 23 (FGF23). Several studies have demonstrated that treatment with burosumab, a blocking neutralizing antibody against FGF23, is better than conventional therapy for severe XLH and has no serious, short-term side effects. Thus, treatment with burosumab may be an option for severe XLH. The present article reviews the conventional and burosumab therapies. In addition to the fact that the long-term efficacy of antibody-based treatment has not been demonstrated, there are other, unresolved issues concerning the burosumab treatment of XLH.
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The regulation of FGF23 under physiological and pathophysiological conditions. Pflugers Arch 2022; 474:281-292. [PMID: 35084563 PMCID: PMC8837506 DOI: 10.1007/s00424-022-02668-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 12/18/2022]
Abstract
Fibroblast growth factor 23 (FGF23) is an important bone hormone that regulates phosphate homeostasis in the kidney along with active vitamin D (1,25(OH)2D3) and parathyroid hormone (PTH). Endocrine effects of FGF23 depend, at least in part, on αKlotho functioning as a co-receptor whereas further paracrine effects in other tissues are αKlotho-independent. Regulation of FGF23 production is complex under both, physiological and pathophysiological conditions. Physiological regulators of FGF23 include, but are not limited to, 1,25(OH)2D3, PTH, dietary phosphorus intake, and further intracellular and extracellular factors, kinases, cytokines, and hormones. Moreover, several acute and chronic diseases including chronic kidney disease (CKD) or further cardiovascular disorders are characterized by early rises in the plasma FGF23 level pointing to further mechanisms effective in the regulation of FGF23 under pathophysiological conditions. Therefore, FGF23 also serves as a prognostic marker in several diseases. Our review aims to comprehensively summarize the regulation of FGF23 in health and disease.
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