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Kanbay M, Copur S, Tanriover C, Yavuz F, Galassi A, Ciceri P, Cozzolino M. The pathophysiology and management of vascular calcification in chronic kidney disease patients. Expert Rev Cardiovasc Ther 2023; 21:75-85. [PMID: 36716079 DOI: 10.1080/14779072.2023.2174525] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
INTRODUCTION Vascular calcification (VC) which is the pathological mineral deposition in the vascular system, predominantly at the intimal and medial layer of the vessel wall, is an important comorbidity in patients with chronic kidney disease (CKD) leading to significant morbidity and mortality while necessitating appropriate treatment. Our review aims to provide an in-depth analysis of the current understanding of VC. AREAS COVERED In this review, we first discuss the pathophysiology of VC in CKD patients, then we explain the methods to predict and assess VC. Afterwards, we provide the currently available as well as the potential therapeutic approaches of VC. We finally discuss our understanding regarding the current situation surrounding VC in our expert opinion section. EXPERT OPINION Predicting, assessing and treating VC is crucial and the future advances in the field of research surrounding VC will potentially occur in one or more of these three areas of clinical management. There is a current lack of evidence and consensus regarding specific therapeutic options for alleviating VC and this situation may not necessitate VC to be determined, detected, and documented before the available options are implemented. Regardless, the prediction and assessment of VC is still important and requires further improvement together with the developments in therapeutic alternatives. The future has the potential to bring better research which would guide and improve the management of this patient group. A more specialized approach consisting of targeted therapies and more tailored management plans for patients with CKD and VC is on the horizon.
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Affiliation(s)
- Mehmet Kanbay
- Department of Medicine, Division of Nephrology, Koc University School of Medicine, Istanbul, Turkey.,Department of Health Sciences, Renal Division, University of Milan, ASST Santi Paolo e Carlo, 20142 Milan, Italy
| | - Sidar Copur
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Cem Tanriover
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Furkan Yavuz
- Department of Medicine, Koc University School of Medicine, Istanbul, Turkey
| | - Andrea Galassi
- Department of Health Sciences, Renal Division, University of Milan, ASST Santi Paolo e Carlo, 20142 Milan, Italy
| | - Paola Ciceri
- Department of Health Sciences, Renal Division, University of Milan, ASST Santi Paolo e Carlo, 20142 Milan, Italy
| | - Mario Cozzolino
- Department of Health Sciences, Renal Division, University of Milan, ASST Santi Paolo e Carlo, 20142 Milan, Italy
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Dörr K, Hödlmoser S, Kammer M, Reindl-Schwaighofer R, Lorenz M, Reiskopf B, Jagoditsch R, Marculescu R, Oberbauer R. Bone Specific Alkaline Phosphatase and Serum Calcification Propensity Are Not Influenced by Etelcalcetide vs. Alfacalcidol Treatment, and Only Bone Specific Alkaline Phosphatase Is Correlated With Fibroblast Growth Factor 23: Sub-Analysis Results of the ETACAR-HD Study. Front Med (Lausanne) 2022; 9:948177. [PMID: 35872799 PMCID: PMC9299083 DOI: 10.3389/fmed.2022.948177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 06/20/2022] [Indexed: 11/13/2022] Open
Abstract
Secondary hyperparathyroidism in chronic kidney disease poses a major risk factor for vascular calcification and high bone turnover, leading to mineralization defects. The aim was to analyze the effect of active vitamin D and calcimimetic treatment on fibroblast growth factor 23 (FGF23), serum calcification propensity (T50), a surrogate marker of calcification stress and bone specific alkaline phosphatase (BAP) in hemodialysis. This is a subanalysis of a randomized trial comparing etelcalcetide vs. alfacalcidol in 62 hemodialysis patients for 1 year. We compared the change of BAP and serum calcification propensity between the two medications and assessed the influence of FGF23 change over time. We found no significant differences in the change of BAP or serum calcification propensity (T50) levels from baseline to study end between treatment arms (difference in change of marker between treatment with etelcalcetide vs. alfacalcidol: BAP : 2.0 ng/ml [95% CI-1.5,5.4], p = 0.3; T50: –15 min [95% CI –49,19], p = 0.4). Using FGF23 change over time, we could show that BAP levels at study end were associated with FGF23 change (–0.14 [95% CI –0.21, –0.08], p < 0.001). We did not observe the same association between FGF23 change and T50 (effect of FGF23 change on T50: 3.7 [95% CI –5.1, 12], p = 0.4; R2 = 0.07 vs. R2 = 0.06). No significant difference was found in serum calcification propensity (T50) values between treatment arms. FGF23 was not associated with serum calcification propensity (T50), but was negatively correlated with BAP underlying its role in the bone metabolism.Clinical Trial Registration[www.ClinicalTrials.gov], identifier [NCT03182699].
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Affiliation(s)
- Katharina Dörr
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
| | | | - Michael Kammer
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
- Section for Clinical Biometrics, Center for Medical Statistics, Informatics and Intelligent Systems (CeMSIIS), Medical University of Vienna, Vienna, Austria
| | | | | | - Bianca Reiskopf
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
| | - Rahel Jagoditsch
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
| | - Rodrig Marculescu
- Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Rainer Oberbauer
- Department of Nephrology, Medical University of Vienna, Vienna, Austria
- *Correspondence: Rainer Oberbauer,
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Alkaline Phosphatase: An Old Friend as Treatment Target for Cardiovascular and Mineral Bone Disorders in Chronic Kidney Disease. Nutrients 2022; 14:nu14102124. [PMID: 35631265 PMCID: PMC9144546 DOI: 10.3390/nu14102124] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/12/2022] [Accepted: 05/17/2022] [Indexed: 11/17/2022] Open
Abstract
Alkaline phosphatase (ALP) is an evolutionary conserved enzyme and widely used biomarker in clinical practice. Tissue-nonspecific alkaline phosphatase (TNALP) is one of four human isozymes that are expressed as distinct TNALP isoforms after posttranslational modifications, mainly in bone, liver, and kidney tissues. Beyond the well-known effects on bone mineralization, the bone ALP (BALP) isoforms (B/I, B1, B1x, and B2) are also involved in the pathogenesis of ectopic calcification. This narrative review summarizes the recent clinical investigations and mechanisms that link ALP and BALP to inflammation, metabolic syndrome, vascular calcification, endothelial dysfunction, fibrosis, cardiovascular disease, and mortality. The association between ALP, vitamin K, bone metabolism, and fracture risk in patients with chronic kidney disease (CKD) is also discussed. Recent advances in different pharmacological strategies are highlighted, with the potential to modulate the expression of ALP directly and indirectly in CKD–mineral and bone disorder (CKD-MBD), e.g., epigenetic modulation, phosphate binders, calcimimetics, vitamin D, and other anti-fracture treatments. We conclude that the significant evidence for ALP as a pathogenic factor and risk marker in CKD-MBD supports the inclusion of concrete treatment targets for ALP in clinical guidelines. While a target value below 120 U/L is associated with improved survival, further experimental and clinical research should explore interventional strategies with optimal risk–benefit profiles. The future holds great promise for novel drug therapies modulating ALP.
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Wang Q, Lin P, Feng L, Ren Q, Xie X, Zhang B. Ameliorative effect of allicin on vascular calcification via inhibiting endoplasmic reticulum stress. Vascular 2021; 30:999-1007. [PMID: 34301159 DOI: 10.1177/17085381211035291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVES Vascular calcification (VC) is an independent predictor for cardiovascular events and mortality. However, there are currently no effective methods to reverse or prevent it. The present study aimed to determine the ameliorative effect of allicin on VC. METHODS VC model of rats was induced by high-dose vitamin D3, which was valued by Alizarin Red staining, calcium contents, and alkaline phosphatase in the aorta. Systolic blood pressure, pulse pressure, and pulse wave velocity were measured to determine aortic stiffness. Protein levels were detected by Western blot. RESULTS Allicin treatment rescued aortic VC and stiffness. The increased protein levels of RUNX2 and BMP2, two markers of osteoblastic phenotype of vascular smooth muscle cells, in the calcified aorta were attenuated by allicin, whereas the decreased levels of calponin and SM22α induced by calcification were improved. Allicin treatment significantly attenuated the increased protein levels of GRP78, GRP94, and CHOP, which are key markers of endoplasmic reticulum stress, in the calcified aorta. The activation of PERK/eIF2α/ATF4 cascades was also prevented by allicin. CONCLUSIONS Allicin could ameliorate aortic VC and stiffness. The ameliorative effect of allicin on VC might be mediated by inhibiting PERK/eIF2α/ATF4 cascades. Our results might provide a new proof for VC treatment.
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Affiliation(s)
- Qin Wang
- Geriatric Department, The Third Hospital of Hangzhou, Hangzhou, China
| | - Ping Lin
- Geriatric Department, The Third Hospital of Hangzhou, Hangzhou, China
| | - Li Feng
- Geriatric Department, The Third Hospital of Hangzhou, Hangzhou, China
| | - Qian Ren
- Geriatric Department, The Third Hospital of Hangzhou, Hangzhou, China
| | - Xiaofeng Xie
- Geriatric Department, The Third Hospital of Hangzhou, Hangzhou, China
| | - Bin Zhang
- Geriatric Department, The Third Hospital of Hangzhou, Hangzhou, China
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Abstract
In chronic kidney disease (CKD), disturbance of several metabolic regulatory mechanisms cause premature ageing, accelerated cardiovascular disease (CVD), and mortality. Single-target interventions have repeatedly failed to improve the prognosis for CKD patients. Epigenetic interventions have the potential to modulate several pathogenetic processes simultaneously. Alkaline phosphatase (ALP) is a robust predictor of CVD and all-cause mortality and implicated in pathogenic processes associated with CVD in CKD.
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Trakarnvanich T, Satirapoj B, Suraamornkul S, Chirananthavat T, Sanpatchayapong A, Claimon T. Effect of Dipeptidyl Peptidase-4 (DPP-4) Inhibition on Biomarkers of Kidney Injury and Vascular Calcification in Diabetic Kidney Disease: A Randomized Controlled Trial. J Diabetes Res 2021; 2021:7382620. [PMID: 34697593 PMCID: PMC8541867 DOI: 10.1155/2021/7382620] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 07/15/2021] [Accepted: 09/29/2021] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Dipeptidyl peptidase-4 (DPP-4) inhibitors improve glycemic control and have pleiotropic effects on kidney injury, albuminuria, and vascular inflammation, especially in animal models. We evaluated the effects of a potent DPP4 inhibitor (gemigliptin) on these processes among patients with diabetic kidney disease (DKD). METHODS This study employed a multicenter, prospective, randomized, placebo-controlled design. A total of 201 participants were enrolled and randomly assigned to one of two groups, one received treatment with 50 mg gemigliptin daily along with standard care for diabetes mellitus for 6 months. The changes in the coronary calcium score (CAC score), cardio-ankle vascular index (CAVI), estimated glomerular filtration rate (eGFR), vascular calcification level, and tubular renal injury marker expression were evaluated at baseline and 6 months. RESULTS In total, 182 patients completed the study. Significant reductions in hemoglobin A1C levels were observed in both groups. The changes in the CAC score, CAVI, eGFR, and level of proteinuria over the 6 months of the study did not significantly differ between the gemigliptin and control groups. However, biomarkers of vascular calcification, including serum bone alkaline phosphatase and kidney injury, including urine neutrophil gelatinase-associated lipocalin (NGAL)/Cr and urine liver fatty acid-binding protein (L-FABP)/Cr, were improved significantly in the gemigliptin treatment group compared with the control group. No serious adverse events were observed during the study. CONCLUSION Our study showed that gemigliptin significantly improved the expression of renal tubular injury biomarkers and vascular calcification levels among patients with DKD; however, gemigliptin did not affect renal function or coronary calcification compared with those observed in the control. A larger study with a longer follow-up is essential to verify these beneficial effects. Clinical Trials. This trial is registered with ClinicalTrials.Gov Identifier NCT04705506.
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Affiliation(s)
| | - Bancha Satirapoj
- Division of Nephrology, Department of Medicine, Phramongkutklao Hospital and College of Medicine, Bangkok, Thailand
| | - Swangjit Suraamornkul
- Faculty of Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand
| | | | - Anoma Sanpatchayapong
- Faculty of Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand
| | - Torpong Claimon
- Faculty of Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand
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Extracellular Nucleotides Regulate Arterial Calcification by Activating Both Independent and Dependent Purinergic Receptor Signaling Pathways. Int J Mol Sci 2020; 21:ijms21207636. [PMID: 33076470 PMCID: PMC7589647 DOI: 10.3390/ijms21207636] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/09/2020] [Accepted: 10/12/2020] [Indexed: 01/02/2023] Open
Abstract
Arterial calcification, the deposition of calcium-phosphate crystals in the extracellular matrix, resembles physiological bone mineralization. It is well-known that extracellular nucleotides regulate bone homeostasis raising an emerging interest in the role of these molecules on arterial calcification. The purinergic independent pathway involves the enzymes ecto-nucleotide pyrophosphatase/phosphodiesterases (NPPs), ecto-nucleoside triphosphate diphosphohydrolases (NTPDases), 5′-nucleotidase and alkaline phosphatase. These regulate the production and breakdown of the calcification inhibitor—pyrophosphate and the calcification stimulator—inorganic phosphate, from extracellular nucleotides. Maintaining ecto-nucleotidase activities in a well-defined range is indispensable as enzymatic hyper- and hypo-expression has been linked to arterial calcification. The purinergic signaling dependent pathway focusses on the activation of purinergic receptors (P1, P2X and P2Y) by extracellular nucleotides. These receptors influence arterial calcification by interfering with the key molecular mechanisms underlying this pathology, including the osteogenic switch and apoptosis of vascular cells and possibly, by favoring the phenotypic switch of vascular cells towards an adipogenic phenotype, a recent, novel hypothesis explaining the systemic prevention of arterial calcification. Selective compounds influencing the activity of ecto-nucleotidases and purinergic receptors, have recently been developed to treat arterial calcification. However, adverse side-effects on bone mineralization are possible as these compounds reasonably could interfere with physiological bone mineralization.
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Chen J, Feng J, Zhou Q, Zheng W, Meng X, Wang Y, Wang J. Intraoperative 99mTc-MIBI-Guided Parathyroidectomy Improves Curative Effect of Parathyroidectomy, Bone Metabolism, and Bone Mineral Density. Am Surg 2020; 87:463-472. [PMID: 33047971 DOI: 10.1177/0003134820951467] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This study aimed to compare the postoperative effects of total parathyroidectomy plus forearm transplantation and radioguided parathyroidectomy on bone metabolism and bone mineral density (BMD). From June 2013 to October 2017, 67 patients with renal secondary hyperparathyroidism (SHPT) received surgical treatment. The control group included 30 cases of classical total parathyroidectomy plus forearm transplantation for SHPT. In the experimental group, 37 patients underwent 99mTc-MIBI-guided parathyroidectomy. Demographics, parathyroid hormone (PTH) level, blood calcium level, and pathological results were compared between the 2 groups. The curative effect of parathyroidectomy and its effect on BMD were also compared. The BMDs in the L1-L4 segments and femoral neck in both groups were significantly improved after operation (all P < .05). The T scores of the L1-L4 segments and femoral neck in both groups were significantly improved after operation (all P < .05). The improvement in the T score of the L4 in the experimental group was significantly higher than that in the control group (P < .05). No significant differences in the improvement in the L1-L3 segments and femoral neck were found between the 2 groups. Both traditional total parathyroidectomy plus forearm transplantation and 99mTc-MIBI-guided parathyroidectomy can improve PTH level, blood calcium level, phosphorus level, bone metabolism, and BMD to varying degrees in patients with SHPT. Compared with the traditional surgery, 99mTc-MIBI-guided parathyroidectomy can improve blood calcium and phosphorus metabolisms, reduce PTH level, and improve the T scores of L4 to a greater extent.
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Affiliation(s)
- Jun Chen
- 56694 Department of Head and Neck Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jialin Feng
- 56694 Department of Head and Neck Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Qinyi Zhou
- 56694 Department of Head and Neck Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Wenjie Zheng
- 56694 Department of Head and Neck Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiangchao Meng
- 56694 Department of Bone and Joint Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - You Wang
- 56694 Department of Bone and Joint Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jiadong Wang
- 56694 Department of Head and Neck Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Huang S, Yu X, Wang H, Zheng J. Elevated serum sortilin is related to carotid plaque concomitant with calcification. Biomark Med 2020; 14:381-389. [PMID: 32077308 DOI: 10.2217/bmm-2019-0472] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Aim: To explore whether elevated serum sortilin was associated with calcified carotid plaque and ischemic stroke. Methods: A total of 171 patients with cardiovascular risk factors were enrolled. Ultrasonography was performed to evaluate calcified plaques and noncalcified plaques. Serum sortilin concentration was measured by ELISA. Results: Serum sortilin level was higher in patients with calcified carotid plaque and positively related to carotid plaque burden, but not with ischemic stroke during the follow-up. Multivariable logistic regression analysis revealed serum sortilin level was an independent determinant for calcified carotid plaque (p = 0.001). Receiving operating characteristic analysis showed an area under the curve of sortilin for carotid calcification was 0.759. Conclusion: Higher serum sortilin level was associated with carotid calcification and severe carotid plaque score.
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Affiliation(s)
- Shanshan Huang
- Department of Ultrasound, Shenzhen Second People’s Hospital/the First Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen 518035, Guangdong, PR China
| | - Xingxing Yu
- Department of Internal Medicine, Zhejiang Provincial People’s Hospital, People’s Hospital of Hangzhou Medical College, Hangzhou 310014, Zhejiang, PR China
| | - Haiqing Wang
- Department of Cardiology, Zhejiang Provincial People’s Hospital, People’s Hospital of Hangzhou Medical College, Hangzhou 310014, Zhejiang, PR China
| | - Jianlei Zheng
- Department of Cardiology, Zhejiang Provincial People’s Hospital, People’s Hospital of Hangzhou Medical College, Hangzhou 310014, Zhejiang, PR China
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Nizet A, Cavalier E, Stenvinkel P, Haarhaus M, Magnusson P. Bone alkaline phosphatase: An important biomarker in chronic kidney disease - mineral and bone disorder. Clin Chim Acta 2019; 501:198-206. [PMID: 31734146 DOI: 10.1016/j.cca.2019.11.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/07/2019] [Accepted: 11/07/2019] [Indexed: 01/02/2023]
Abstract
Increased cardiovascular morbidity and mortality in chronic kidney disease (CKD) represents an emerging major health problem. Indeed, disturbances in mineral and bone metabolism occur frequently in CKD and are termed chronic kidney disease - mineral and bone disorder (CKD-MBD). These can lead to cardiovascular pathology, resulting in an increased cardiovascular risk. Bone alkaline phosphatase (BALP) is essential for biomineralization. Recent findings demonstrate a crucial role for BALP in the pathogenesis of vascular calcification and identified it as a promising predictor of mortality in CKD. In conjunction with parathyroid hormone (PTH), serum BALP has been suggested as a biomarker of bone turnover in CKD-MBD. In contrast to PTH, serum BALP demonstrates a lower variability and may thus be better suited for the diagnosis and longitudinal follow-up of bone turnover. The linear association with mortality, compared to the U-shaped curve for PTH, is an additional advantage, making BALP more suitable than PTH as a treatment target in CKD. Here we review the main characteristics of alkaline phosphatase isozymes/isoforms and the various assays currently used in clinical routine laboratories. We also discuss the role of BALP in both physiological and pathological mineralization, and the clinical benefit of BALP determination in CKD.
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Affiliation(s)
- Adrien Nizet
- Department of Clinical Chemistry, University Hospital Center of Liège, University of Liège, Liège, Belgium
| | - Etienne Cavalier
- Department of Clinical Chemistry, University Hospital Center of Liège, University of Liège, Liège, Belgium.
| | - Peter Stenvinkel
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Campus Flemingsberg, Stockholm, Sweden
| | - Mathias Haarhaus
- Division of Renal Medicine, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Campus Flemingsberg, Stockholm, Sweden; Department of Clinical Chemistry, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden; Diaverum Sweden, Stockholm, Sweden
| | - Per Magnusson
- Department of Clinical Chemistry, Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
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Whyte MP, McAlister WH, Mumm S, Bierhals AJ. No vascular calcification on cardiac computed tomography spanning asfotase alfa treatment for an elderly woman with hypophosphatasia. Bone 2019; 122:231-236. [PMID: 30825650 DOI: 10.1016/j.bone.2019.02.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Revised: 02/01/2019] [Accepted: 02/27/2019] [Indexed: 12/28/2022]
Abstract
Hypophosphatasia (HPP) is the inborn-error-of-metabolism characterized enzymatically by insufficient activity of the tissue-nonspecific isoenzyme of alkaline phosphatase (TNSALP) and caused by either mono- or bi-allelic loss-of-function mutation(s) of the gene ALPL that encodes this cell surface phosphomonoester phosphohydrolase. In HPP, the natural substrates of TNSALP accumulate extracellularly and include inorganic pyrophosphate (PPi), a potent inhibitor of biomineralization. This PPi excess leads to rickets or osteomalacia in all but the most mild "odonto" form of the disease. Adults with HPP understandably often also manifest calcium PPi dihydrate deposition, whereas enthesopathy and calcific periarthritis from hydroxyapatite (HA) crystal deposition can seem paradoxical in face of the defective skeletal mineralization. In 2015, asfotase alfa (AA), a HA-targeted TNSALP, was approved multinationally as an enzyme replacement therapy for HPP. AA hydrolyzes extracellular PPi (ePPi) and in HPP enables HA crystals to grow and mineralize skeletal matrix. In direct contrast to HPP, deficiency of ePPi characterizes the inborn-errors-of-metabolism generalized arterial calcification of infancy (GACI) and pseudoxanthoma elasticum (PXE). In GACI and PXE, deficiency of ePPi leads to ectopic mineralization including vascular calcification (VC). Therefore, in HPP, ectopic mineralization including VC could hypothetically result from, or be exacerbated by, the persistently high circulating TNSALP activity that occurs during AA treatment. Herein, using a routine computed tomography (CT) method to quantitate coronary artery calcium, we found no ectopic mineralization in the heart of an elderly woman with HPP before or after 8 months of AA treatment. Subsequently, investigational high-resolution peripheral quantitative CT and dual-energy X-ray absorptiometry showed absence of peripheral artery and aortic calcium after further AA treatment. Investigation of additional adults with HPP could reveal if the superabundance of ePPi protects against VC, and whether long-term AA therapy causes or exacerbates any ectopic mineralization.
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Affiliation(s)
- Michael P Whyte
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA; Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - William H McAlister
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
| | - Steven Mumm
- Division of Bone and Mineral Diseases, Department of Internal Medicine, Washington University School of Medicine at Barnes-Jewish Hospital, St. Louis, MO 63110, USA; Center for Metabolic Bone Disease and Molecular Research, Shriners Hospitals for Children - St. Louis, St. Louis, MO 63110, USA.
| | - Andrew J Bierhals
- Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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