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Liu ES, LeBoff MS. Editorial: the role of vitamin D metabolites in the evaluation of bone health: are they physiologically relevant? J Bone Miner Res 2024; 39:1-2. [PMID: 38630885 DOI: 10.1093/jbmr/zjad012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 10/19/2023] [Accepted: 11/01/2023] [Indexed: 04/19/2024]
Affiliation(s)
- Eva S Liu
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Assistant Professor of Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Meryl S LeBoff
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Professor of Medicine, Harvard Medical School, Boston, MA 02115, United States
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Mieszkowski J, Kochanowicz A, Piskorska E, Niespodziński B, Siódmiak J, Buśko K, Stankiewicz B, Olszewska-Słonina D, Antosiewicz J. Serum levels of bone formation and resorption markers in relation to vitamin D status in professional gymnastics and physically active men during upper and lower body high-intensity exercise. J Int Soc Sports Nutr 2021; 18:29. [PMID: 33849553 PMCID: PMC8045337 DOI: 10.1186/s12970-021-00430-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 03/30/2021] [Indexed: 12/27/2022] Open
Abstract
Purpose/introduction To compare serum levels of bone turnover markers in athletes and non-athletes, and to evaluate the relationship between serum levels of vitamin D metabolites and exercise-induced changes in biomarker levels. Methods Sixteen elite male artistic gymnasts (EG; 21.4 ± 0.8 years-old) and 16 physically active men (the control group, PAM; 20.9 ± 1.2 years-old) performed lower and upper body 30-s Wingate anaerobic tests (LBWT and UBWT, respectively). For biomarker analysis, blood samples were collected before, and 5 and 30 min after exercise. Samples for vitamin D levels were collected before exercise. N-terminal propeptide of type I collagen (PINP) was analysed as a marker of bone formation. C-terminal telopeptide of type I collagen (CTX) was analysed as a marker of bone resorption. Results UBWT fitness readings were better in the EG group than in the PAM group, with no difference in LBWT readings between the groups. UBWT mean power was 8.8% higher in subjects with 25(OH)D3 levels over 22.50 ng/ml and in those with 24,25(OH)2D3 levels over 1.27 ng/ml. Serum CTX levels increased after both tests in the PAM group, with no change in the EG group. PINP levels did not change in either group; however, in PAM subjects with 25(OH)D3 levels above the median, they were higher than those in EG subjects. Conclusion Vitamin D metabolites affect the anaerobic performance and bone turnover markers at rest and after exercise. Further, adaptation to physical activity modulates the effect of anaerobic exercise on bone metabolism markers.
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Affiliation(s)
- Jan Mieszkowski
- Department of Gymnastics and Dance, Gdansk University of Physical Education and Sport, Gdansk, Poland.
| | - Andrzej Kochanowicz
- Department of Gymnastics and Dance, Gdansk University of Physical Education and Sport, Gdansk, Poland
| | - Elżbieta Piskorska
- Department of Pathobiochemistry and Clinical Chemistry, Nicolaus Copernicus University Collegium Medicum, Bydgoszcz, Poland
| | - Bartłomiej Niespodziński
- Kazimierz Wielki University, Department of Anatomy and Biomechanics, Institute of Physical Education, Bydgoszcz, Poland
| | - Joanna Siódmiak
- Department of Laboratory Medicine, L. Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Krzysztof Buśko
- Kazimierz Wielki University, Department of Anatomy and Biomechanics, Institute of Physical Education, Bydgoszcz, Poland
| | - Blazej Stankiewicz
- Kazimierz Wielki University, Department of Anatomy and Biomechanics, Institute of Physical Education, Bydgoszcz, Poland
| | - Dorota Olszewska-Słonina
- Department of Pathobiochemistry and Clinical Chemistry, Nicolaus Copernicus University Collegium Medicum, Bydgoszcz, Poland
| | - Jędrzej Antosiewicz
- Department of Bioenergetics and Physiology of Exercise, Medical University of Gdansk, Gdansk, Poland.
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Chapter 4.1: Treatment of CKD-MBD targeted at lowering high serum phosphorus and maintaining serum calcium. Kidney Int 2016; 76113:S50-99. [PMID: 26746397 DOI: 10.1038/ki.2009.192] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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van de Peppel J, van Leeuwen JPTM. Vitamin D and gene networks in human osteoblasts. Front Physiol 2014; 5:137. [PMID: 24782782 PMCID: PMC3988399 DOI: 10.3389/fphys.2014.00137] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 03/20/2014] [Indexed: 12/27/2022] Open
Abstract
Bone formation is indirectly influenced by 1,25-dihydroxyvitamin D3 (1,25D3) through the stimulation of calcium uptake in the intestine and re-absorption in the kidneys. Direct effects on osteoblasts and bone formation have also been established. The vitamin D receptor (VDR) is expressed in osteoblasts and 1,25D3 modifies gene expression of various osteoblast differentiation and mineralization-related genes, such as alkaline phosphatase (ALPL), osteocalcin (BGLAP), and osteopontin (SPP1). 1,25D3 is known to stimulate mineralization of human osteoblasts in vitro, and recently it was shown that 1,25D3 induces mineralization via effects in the period preceding mineralization during the pre-mineralization period. For a full understanding of the action of 1,25D3 in osteoblasts it is important to get an integrated network view of the 1,25D3-regulated genes during osteoblast differentiation and mineralization. The current data will be presented and discussed alluding to future studies to fully delineate the 1,25D3 action in osteoblast. Describing and understanding the vitamin D regulatory networks and identifying the dominant players in these networks may help develop novel (personalized) vitamin D-based treatments. The following topics will be discussed in this overview: (1) Bone metabolism and osteoblasts, (2) Vitamin D, bone metabolism and osteoblast function, (3) Vitamin D induced transcriptional networks in the context of osteoblast differentiation and bone formation.
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Affiliation(s)
- Jeroen van de Peppel
- Department of Internal Medicine, Bone and Calcium Metabolism Erasmus MC, Rotterdam, Netherlands
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Curtis KM, Aenlle KK, Roos BA, Howard GA. 24R,25-dihydroxyvitamin D3 promotes the osteoblastic differentiation of human mesenchymal stem cells. Mol Endocrinol 2014; 28:644-58. [PMID: 24597546 DOI: 10.1210/me.2013-1241] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Although 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3] is considered the most biologically active vitamin D3 metabolite, the vitamin D3 prohormone, 25-hydroxyvitamin D3 [25(OH)D3], is metabolized into other forms, including 24R,25-dihydroxyvitamin D3 [24R,25(OH)2D3]. Herein we show that 24R,25(OH)2D3 is fundamental for osteoblastic differentiation of human mesenchymal stem cells (hMSCs). Our approach involved analyses of cell proliferation, alkaline phosphatase activity, and pro-osteogenic genes (collagen 1A1, osteocalcin, vitamin D receptor [VDR], vitamin D3-hydroxylating enzymes [cytochrome P450 hydroxylases: CYP2R1, CYP27A1, CYP27B1 and CYP24A1]) and assessment of Ca(2+) mineralization of extracellular matrix. 24R,25(OH)2D3 inhibited hMSC proliferation, decreased 1α-hydroxylase (CYP27B) expression, thereby reducing the ability of hMSCs to convert 25(OH)D3 to 1α,25(OH)2D3, and promoted osteoblastic differentiation through increased alkaline phosphatase activity and Ca(2+) mineralization. 24R,25(OH)2D3 decreased expression of the 1α,25(OH)2D3 receptor, VDR. 24R,25(OH)2D3 but not 1α,25(OH)2D3 induced Ca(2+) mineralization dependent on the absence of the glucocorticoid analog, dexamethasone. To elucidate the mechanism(s) for dexamethasone-independent 1α,25(OH)2D3 inhibition/24R,25(OH)2D3 induction of Ca(2+) mineralization, we demonstrated that 1α,25(OH)2D3 increased whereas 24R,25(OH)2D3 decreased reactive oxygen species (ROS) production. 25(OH)D3 also decreased ROS production, potentially by conversion to 24R,25(OH)2D3. Upon inhibition of the vitamin D3-metabolizing enzymes (cytochrome P450s), 25(OH)D3 increased ROS production, potentially due to its known (low) affinity for VDR. We hypothesize that vitamin D3 actions on osteoblastic differentiation involve a regulatory relationship between 24R,25(OH)2D3 and 1α,25(OH)2D3. These results implicate 24R,25(OH)2D3 as a key player during hMSC maturation and bone development and support the concept that 24R,25(OH)2D3 has a bioactive role in the vitamin D3 endocrine system.
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Affiliation(s)
- Kevin M Curtis
- Geriatric Research, Education, and Clinical Center and Research Service (K.M.C., K.K.A., B.A.R., G.A.H.), Bruce W. Carter Veterans Affairs Medical Center, Miami, Florida 33125; and Departments of Biochemistry and Molecular Biology (K.M.C., G.A.H.), Medicine (B.A.R., G.A.H.), and Neurology (B.A.R.), University of Miami Miller School of Medicine, Miami, Florida 33101
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van Driel M, van Leeuwen JPTM. Vitamin D endocrine system and osteoblasts. BONEKEY REPORTS 2014; 3:493. [PMID: 24605210 DOI: 10.1038/bonekey.2013.227] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 12/04/2013] [Indexed: 01/12/2023]
Abstract
The interaction between vitamin D and osteoblasts is complex. In the current review we will give an overview of the current knowledge of the vitamin D endocrine system in osteoblasts. The presence of the vitamin D receptor in osteoblasts enables direct effects of 1α,25dihydroxyvitamin D3 (1α,25D3) on osteoblasts, but the magnitude of the effects is subject to the presence of many other factors. Vitamin D affects osteoblast proliferation, as well as differentiation and mineralization, but these effects vary with the timing of treatment, dosage and origin of the osteoblasts. Vitamin D effects on differentiation and mineralization are mostly stimulatory in human and rat osteoblasts, and inhibitory in murine osteoblasts. Several genes and mechanisms are studied to explain the effects of 1α,25D3 on osteoblast differentiation and bone formation. Besides the classical VDR, osteoblasts also express a membrane-localized receptor, and in vitro studies have shown that osteoblasts are capable of the synthesis of 1α,25D3.
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Edouard T, Husseini A, Glorieux FH, Rauch F. Serum 24,25-dihydroxyvitamin D concentrations in osteogenesis imperfecta: relationship to bone parameters. J Clin Endocrinol Metab 2012; 97:1243-9. [PMID: 22319032 DOI: 10.1210/jc.2011-3015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Several studies suggest that 24,25-dihydroxyvitamin D [24,25(OH)₂D] may have an effect on bone mass and metabolism. OBJECTIVE We evaluated the relationship between serum 24,25(OH)₂D levels and bone density and bone metabolism in children with a primary bone disorder-osteogenesis imperfecta (OI). MATERIALS AND METHODS The study included 132 patients (age, 1.1 to 17.9 yr; 67 girls) with OI types I, III, or IV who had not received bisphosphonate treatment at the time of analysis. RESULTS Serum 24,25(OH)₂D levels were significantly higher in OI type III than in OI type I or IV. Serum 24,25(OH)₂D concentrations were positively correlated with serum 25-hydroxyvitamin D (25OHD) levels and negatively correlated with serum PTH levels, and were not correlated with serum 1α,25-dihydroxyvitamin D [1,25(OH)₂D]. The ratio between serum 24,25(OH)₂D and 25OHD was negatively correlated with age and was independent of serum 25OHD concentrations. Regression analysis revealed that OI severity (P = 0.04), serum 25OHD levels (P < 0.001), and serum PTH concentrations (P = 0.045), but not age, gender, or serum 1,25(OH)₂D, were independent predictors of serum 24,25(OH)₂D levels. No correlation was found between serum 24,25(OH)₂D levels or the ratio between serum 24,25(OH)₂D and 25OHD and lumbar spine bone mineral density z-scores or bone marker levels (serum osteocalcin and urinary collagen type I N-telopeptide) after adjusting for OI type, age, and gender. CONCLUSION Patients with more severe OI type had higher 24,25(OH)₂D serum levels and higher serum 24,25(OH)₂D to 25OHD ratios, suggesting an increased 25OHD-24-hydroxylase activity.
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Affiliation(s)
- Thomas Edouard
- Genetics Unit, Shriners Hospital for Children, 1529 Cedar Avenue, Montréal, Québec, Canada H3G 1A6
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Taskapan H. Is 24,25(OH)D level really high in dialysis patients with high FGF23 levels? Int Urol Nephrol 2012; 44:1135-44. [PMID: 22467088 DOI: 10.1007/s11255-012-0157-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Accepted: 03/05/2012] [Indexed: 12/20/2022]
Abstract
Deficiency of 1,25-dihydroxyvitamin D [1,25(OH)(2)D] and excessive fibroblast growth factor (FGF23) are suggested to be associated with increased mortality in patients with chronic kidney disease (CKD). Generally, 24-hydroxylation has been considered the first step in the degradation pathway of 1,25(OH)(2)D and 25(OH)D. 24,25-dihydroxyvitamin D [24,25(OH)(2)D] was believed to be a degradation product, with no important biological effects. However, some data have accumulated showing that 24,25(OH)(2)D has biological effects on its own. Under conditions of eucalcemia, the synthesis of 24,25(OH)(2)D is increased, and the synthesis of 1,25(OH)(2)D is decreased. In patients with CKD, both high parathyroid hormone levels, which decrease the activity of enzyme CYP24A1 (24-hydroxylase), and high FGF23 levels, which increase the activity of enzyme CYP24A1, were often detected. However, information about 24,25(OH)(2)D levels in these patients is very limited. Whether compensatory changes in levels of FGF23 and 24,25(OH)(2)D in CKD patients are protective or harmful remain unknown issues. Therefore, more studies are needed to identify the nature of the interactions between these molecules and to fully elucidate their clinical significance.
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Affiliation(s)
- Hulya Taskapan
- Nephrology Department, Inonu University Medical Faculty, 4400 Malatya, Turkey.
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Palmer SC, McGregor DO, Craig JC, Elder G, Macaskill P, Strippoli GF. Vitamin D compounds for people with chronic kidney disease not requiring dialysis. Cochrane Database Syst Rev 2009:CD008175. [PMID: 19821446 DOI: 10.1002/14651858.cd008175] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND Vitamin D compounds are used to suppress elevated serum parathyroid hormone (PTH) in people with chronic kidney disease (CKD). OBJECTIVES To assess the efficacy of vitamin D therapy on biochemical, bone, cardiovascular, and mortality outcomes in people with CKD and not requiring dialysis. SEARCH STRATEGY We searched The Cochrane Renal Group's specialised register, Cochrane's Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and reference lists of retrieved articles. SELECTION CRITERIA Randomised controlled trials (RCTs) comparing different forms, schedules, or routes of administration of vitamin D compounds for people with CKD not requiring dialysis were included. Vitamin D compounds were defined as established (calcitriol, alfacalcidol, 24,25(OH)(2)vitamin D(3)) or newer (doxercalciferol, maxacalcitol, paricalcitol, falecalcitriol) vitamin D compounds. DATA COLLECTION AND ANALYSIS Data were extracted by two authors. Statistical analyses were performed using the random effects model. Results were summarized as risk ratio (RR) for dichotomous outcomes or mean differences (MD) for continuous outcomes with 95% confidence intervals (CI). MAIN RESULTS Sixteen studies (894 patients) were included. No formulation, route, or schedule of vitamin D compound was found to alter the mortality risk or need for dialysis. Vitamin D compounds significantly lowered serum PTH (4 studies, 153 patients: MD -49.34 pg/mL, 95% CI -85.70 to -12.97 (-5.6 pmol/L, 95% CI -9.77 to -1.48)) and were more likely to reduce serum PTH > 30% from baseline value (264 patients: RR 7.87, 95% CI 4.87 to 12.73). Vitamin D treatment was associated with increased end of treatment serum phosphorus (3 studies, 140 patients: MD 0.37 mg/dL, 95% CI 0.09, 0.66 (0.12 mmol/L, 95% CI 0.03, 0.21)) and serum calcium (5 studies, 184 patients: MD 0.20 mg/dL, 95% CI 0.17 to 0.23 (0.05 mmol/L, 95% CI 0.04 to 0.06)). Few data were available comparing intermittent with daily vitamin D administration, or other schedules of dosing. AUTHORS' CONCLUSIONS There are not sufficient data to determine the effect of vitamin D compounds on mortality and cardiovascular outcomes in people with CKD not requiring dialysis. While vitamin D compounds reduce serum PTH (49.3 pg/mL (5.6 pmol/L)) compared with placebo, the relative clinical benefits of PTH lowering versus treatment-related increases in serum phosphorus and calcium remain to be understood.
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Affiliation(s)
- Suetonia C Palmer
- Renal Division, Brigham and Women's Hospital, Harvard Medical School, Harvard Institute of Medicine, Room 550, 4 Blackfan Street, Boston, MA, USA, 02115
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Abstract
BACKGROUND Kidney disease, especially chronic kidney disease (CKD), is a worldwide public health problem with serious adverse health consequences for affected individuals. Secondary hyperparathyroidism, a disorder characterized by elevated serum parathyroid hormone levels, and alteration of calcium and phosphorus homeostasis are common metabolic complications of CKD that may impact cardiovascular health. MATERIALS AND METHODS Here, we systematically review published reports from recent observational studies and clinical trials that examine markers of altered mineral metabolism and clinical outcomes in patients with CKD. RESULTS Mineral metabolism disturbances begin early during the course of chronic kidney disease, and are associated with cardiovascular disease and mortality in observational studies. Vascular calcification is one plausible mechanism connecting renal-related mineral metabolism with cardiovascular risk. Individual therapies to correct mineral metabolism disturbances have been associated with clinical benefit in some observational studies; clinical trials directed at more comprehensive control of this problem are warranted. CONCLUSIONS There exists a potential to improve outcomes for patients with CKD through increased awareness of the Bone Metabolism and Disease guidelines set forth by the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative. Future studies may include more aggressive therapy with a combination of agents that address vitamin D deficiency, parathyroid hormone and phosphorus excess, as well as novel agents that modulate circulating promoters and inhibitors of calcification.
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Affiliation(s)
- B Kestenbaum
- University of Washington, Seattle, WA 98104-2499, USA.
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van Driel M, Koedam M, Buurman CJ, Roelse M, Weyts F, Chiba H, Uitterlinden AG, Pols HAP, van Leeuwen JPTM. Evidence that both 1α,25-dihydroxyvitamin D3 and 24-hydroxylated D3 enhance human osteoblast differentiation and mineralization. J Cell Biochem 2006; 99:922-35. [PMID: 16741965 DOI: 10.1002/jcb.20875] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Vitamin D plays a major role in the regulation of mineral homeostasis and affects bone metabolism. So far, detailed knowledge on the vitamin D endocrine system in human bone cells is limited. Here we investigated the direct effects of 1alpha,25-(OH)2D3 on osteoblast differentiation and mineralization. Also, we studied the impact of 24-hydroxylation, generally considered as the first step in the degradation pathway of vitamin D, as well as the role of the nuclear and presumed membrane vitamin D receptor (VDR). For this we used a human osteoblast cell line (SV-HFO) that has the potency to differentiate during culture forming a mineralized extracellular matrix in a 3-week period. Transcriptional analyses demonstrated that both 1alpha,25-(OH)2D3 and the 24-hydroxylated metabolites 24R,25-(OH)2D3 and 1alpha,24R,25-(OH)3D3 induced gene transcription. All metabolites dose-dependently increased alkaline phosphatase (ALP) activity and osteocalcin (OC) production (protein and RNA), and directly enhanced mineralization. 1Alpha,24R,25-(OH)3D3 stimulated ALP activity and OC production most potently, while for mineralization it was equipotent to 1alpha,25-(OH)2D3. The nuclear VDR antagonist ZK159222 almost completely blocked the effects of all metabolites. Interestingly, 1beta,25-(OH)2D3, an inhibitor of membrane effects of 1alpha,25-(OH)2D3 in the intestine, induced gene transcription and increased ALP activity, OC expression and mineralization. In conclusion, not only 1alpha,25-(OH)2D3, but also the presumed 24-hydroxylated "degradation" products stimulate differentiation of human osteoblasts. 1Alpha,25-(OH)2D3 as well as the 24-hydroxylated metabolites directly enhance mineralization, with the nuclear VDR playing a central role. The intestinal antagonist 1beta,25-(OH)2D3 acts in bone as an agonist and directly stimulates mineralization in a nuclear VDR-dependent way.
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Affiliation(s)
- M van Driel
- Department of Internal Medicine, Erasmus MC, 3015 GE Rotterdam, The Netherlands
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Slatopolsky E, Cozzolino M, Lu Y, Finch J, Dusso A, Staniforth M, Wein Y, Webster J. Efficacy of 19-Nor-1,25-(OH)2D2 in the prevention and treatment of hyperparathyroid bone disease in experimental uremia. Kidney Int 2003; 63:2020-7. [PMID: 12753289 DOI: 10.1046/j.1523-1755.2003.00029.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The control of parathyroid hyperplasia and high circulating parathyroid hormone (PTH) levels is crucial in preventing secondary hyperparathyroidism (SH) in renal failure. Parathyroid gland enlargement and elevated levels of PTH are major contributors to increase bone resorption, a feature of renal osteodystrophy. METHODS These studies assessed the efficacy of the 1,25(OH)2D3 analog, 19-Nor-1,25(OH)2D2 (19-Nor), in the prevention (protocol I) and treatment (protocol II) of SH and renal osteodystrophy in uremic rats. In protocol I, normal and uremic rats were fed a high phosphorus diet for 2 months; uremic rats were administered intraperitoneal injections of either vehicle or 19-Nor (200 ng three times a week). In protocol II, normal and uremic rats were fed a high phosphorus diet for 4 months; 2 months after the onset of uremia, rats were administered either intraperitoneal vehicle or 19-Nor (200 ng three times a week). Serum PTH and bone histology were used to assess the degree of SH. RESULTS 19-Nor was effective in preventing (protocol I) and suppressing (protocol II) the significant SH induced by uremia and further enhanced by a high phosphorus diet. In protocol I, bone histology in uremic controls showed a threefold increase in the cancellous bone mass compared to normal rats. This expansion in unmineralized bone was accompanied by 5-, 1.5-, and 7-fold increases in eroded surface, mineralization lag time (MLT), and bone formation rate (BFR/BS), respectively. Moreover, cortical bone porosity in untreated uremic rats increased 267-fold compared to normal animals. 19-Nor ameliorated these changes in cancellous and cortical bone. In protocol II, the reported indices worsened even further. In contrast, 2 months of 19-Nor treatment improved bone histology by reducing cortical bone porosity, woven bone formation, MLT, and BFR/BS. CONCLUSION In an experimental model of chronic renal failure (CRF), 19-Nor prevents SH and ameliorates the histomorphometric changes induced by uremia and high phosphorus diet. In addition, 19-Nor suppresses serum PTH and improves bone histology in uremic rats with established severe SH. Further studies in patients with CRF are necessary to define the clinical applicability of 19-Nor on bone histology in humans.
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Affiliation(s)
- Eduardo Slatopolsky
- Renal Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
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Abstract
The 1alpha-hydroxylated metabolite of 25-hydroxyvitamin D(3), 1,25-dihydroxyvitamin D(3), is the biologically most active metabolite of vitamin D. The 24-hydroxylated metabolites were generally considered as degradation products of a catabolic pathway finally leading to excretion of calcitroic acid. Studies with analogues fluorinated at the C-24 position did not indicate a physiological function for 24R,25(OH)(2)D(3). Nevertheless throughout the years various studies showed biologic effects of other metabolites than 1alpha,25(OH)(2)D(3). In particular the metabolite 24R,25(OH)(2)D(3) has been functionally analyzed, e.g. with respect to a role in normal chicken egg hatchability and effects on chondrocytes in the resting zone of cartilage. Numerous studies have shown the presence of the vitamin D receptor in bone cells and effects of 1alpha,25(OH)(2)D(3) on bone and bone cells. Also for 24R,25(OH)(2)D(3) studies have been performed focusing on effects on bone and bone cells. The purpose of this review is to summarize the data regarding 24R,25(OH)(2)D(3) and bone and to evaluate its role in bone biology.
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Affiliation(s)
- J P van Leeuwen
- Department of Internal Medicine, Erasmus Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands.
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Sanchez CP, Goodman WG, Salusky IB. Prevention of Renal Osteodystrophy in Predialysis Patients. Am J Med Sci 1999. [DOI: 10.1016/s0002-9629(15)40553-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Derkx P, Nigg AL, Bosman FT, Birkenhäger-Frenkel DH, Houtsmuller AB, Pols HA, van Leeuwen JP. Immunolocalization and quantification of noncollagenous bone matrix proteins in methylmethacrylate-embedded adult human bone in combination with histomorphometry. Bone 1998; 22:367-73. [PMID: 9556137 DOI: 10.1016/s8756-3282(97)00299-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The noncollagenous proteins (NCPs) in the bone matrix comprise growth factors with distinct cellular effects and a series of proteins with less clear biological actions. In order to understand the role of these proteins in bone metabolism and in bone diseases, it is crucial to determine their localization and quantity in normal and pathological bone. We have developed an immunohistochemical method to detect osteopontin, osteocalcin, bone sialoprotein, osteonectin, decorin, biglycan, and the growth factors transforming growth factor-beta, insulin-like growth factor-I, and bone morphogenetic protein-2 both in bone matrix and in bone cells of adult human bone embedded in methylmethacrylate. Immunohistochemistry and standard bone histomorphometry in adjacent sections allows the localization of the proteins to metabolically active sites in bone. The protocol works with several fixatives and with bone specimens obtained and embedded to over 20 years ago. Most importantly, we developed a procedure to specifically stain the mineralized matrix green in combination with a red staining of the NCPs. Using digital image analysis it is possible to quantify the relative amounts of NCPs (microm2 NCP area/microm2 mineralized matrix area). Within one biopsy of normal bone cut at four different heights (at a distance of 100 microm), two adjacent sections were stained either for osteopontin or osteonectin. Thirty trabecular and 20 cortical microscopic fields were measured, and the NCP:mineralized matrix ratio was calculated. Stepwise analysis of the standard error of the mean of the NCP:mineralized matrix ratios showed that measuring about 50 microscopic fields is sufficient to obtain representative data with a small confidence interval. In conclusion, the present procedure enables to quantify NCPs and to relate their presence to metabolically active sites in bone. The quantification provides the opportunity to monitor differences in distribution (e.g., cortical vs. trabecular) and differences between normal and pathological conditions and to assess changes in matrix composition during treatment. This can be done by reanalyzing bone biopsies obtained in the past, e.g., during clinical trials. Therefore, the present technique will be a valuable tool for the study of noncollagenous bone matrix proteins in human bone.
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Affiliation(s)
- P Derkx
- Department of Internal Medicine III, Erasmus University Medical School, Rotterdam, The Netherlands
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KAZAMA JJ, WA MFUKAGAWA, YI H, KUMAGAI M, YAMATO H, TANIGUCHI N, GEJYO F, ARAKAWA M, OZAWA H, KUROKAWA K. 24R, 25-Dihydroxyvitamin D3ameliorates the high-turnover bone diseases without suppressing parathyroid function in chronic renal failure in rats. Nephrology (Carlton) 1996. [DOI: 10.1111/j.1440-1797.1996.tb00114.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Derkx P, Birkenhäger-Frenkel DH. A thionin stain for visualizing bone cells, mineralizing fronts and cement lines in undecalcified bone sections. Biotech Histochem 1995; 70:70-4. [PMID: 7578591 DOI: 10.3109/10520299509108320] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A staining method is described using thionin, for undecalcified deacrylated bone sections. RNA is stained purplish violet, allowing still active osteoblasts to be distinguished from lining cells. Staining intensity of mineralized bone is related to the degree of mineralization. Mineralizing fronts and cement lines are visualized clearly. Lamellae show an alternate pattern. Histomorphometric parameters such as osteon thickness and interstitial bone thickness can be measured without using polarized light. The mineralizing front can be assessed and expressed as a percentage of the osteoblast-covered interface between osteoid and mineralized bone. The stain is also useful for qualitative assessment of metabolic bone disease. Thionin stained sections can be kept for at least one year when stored in the dark at 7 C.
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Affiliation(s)
- P Derkx
- Department of Pathology, Erasmus University, Rotterdam, The Netherlands
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