1
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Harmsen IM, van den Beukel T, Kok M, Visseren FLJ, de Jong PA, Papapoulos SE, Spiering W. Cyclical Etidronate Reduces the Progression of Arterial Calcifications in Patients with Pseudoxanthoma Elasticum: A 6-Year Prospective Observational Study. J Clin Med 2024; 13:4612. [PMID: 39200754 DOI: 10.3390/jcm13164612] [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: 06/02/2024] [Revised: 07/24/2024] [Accepted: 07/31/2024] [Indexed: 09/02/2024] Open
Abstract
Background: Pseudoxanthoma elasticum (PXE), a rare genetic disorder presenting with slowly progressing calcification of various tissues, including the arteries, is caused by mutations in the ABCC6 gene that lead to the reduction of pyrophosphate, a natural inhibitor of calcification. We showed that, compared to a placebo, the cyclical administration of etidronate, a stable pyrophosphate analog, significantly reduced arterial calcification assessed by low-dose CT scans after one year. The aim of the present prospective, single center, observational cohort study was the assessment of the efficacy and safety of cyclical etidronate in patients treated for periods longer than one year. Methods: Seventy-three patients were followed for a median of 3.6 years without etidronate and 2.8 years with etidronate, and each patient served as their own control. Results: The median absolute yearly progression of total calcification volume during the period with etidronate (388 [83-838] µL) was significantly lower than that without etidronate (761 [362-1415] µL; p < 0.001). The rates of the relative progression of arterial calcification were 11.7% (95% CI: 9.6-13.9) without etidronate compared to 5.3% (95% CI: 3.7-7.0) with etidronate, after adjustment for confounders. Conclusions: The cyclical administration of etidronate for nearly 3 years significantly reduced the progression rate of arterial calcification in patients with PXE with pre-existing calcifications without any serious adverse effects.
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Affiliation(s)
- Iris M Harmsen
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, 3508 GA Utrecht, The Netherlands
| | - Tim van den Beukel
- Department of Radiology, University Medical Center Utrecht, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - Madeleine Kok
- Department of Radiology, University Medical Center Utrecht, Utrecht University, 3584 CX Utrecht, The Netherlands
- Department of Radiology & Nuclear Medicine, Rijnstate, 6815 AD Arnhem, The Netherlands
| | - Frank L J Visseren
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, 3508 GA Utrecht, The Netherlands
| | - Pim A de Jong
- Department of Radiology, University Medical Center Utrecht, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - Socrates E Papapoulos
- Center for Bone Quality, Department of Endocrinology, Leiden University Medical Centre, 2333 ZA Leiden, The Netherlands
| | - Wilko Spiering
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, 3508 GA Utrecht, The Netherlands
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Brampton C, Pomozi V, Le Corre Y, Zoll J, Kauffenstein G, Ma C, Hoffmann PR, Martin L, Le Saux O. Bone Marrow-Derived ABCC6 Is an Essential Regulator of Ectopic Calcification In Pseudoxanthoma Elasticum. J Invest Dermatol 2024; 144:1772-1783.e3. [PMID: 38367909 PMCID: PMC11260544 DOI: 10.1016/j.jid.2024.01.026] [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: 10/30/2023] [Revised: 12/31/2023] [Accepted: 01/26/2024] [Indexed: 02/19/2024]
Abstract
Physiological calcification of soft tissues is a common occurrence in aging and various acquired and inherited disorders. ABCC6 sequence variations cause the calcification phenotype of pseudoxanthoma elasticum (PXE) as well as some cases of generalized arterial calcification of infancy, which is otherwise caused by defective ENPP1. ABCC6 is primarily expressed in the liver, which has given the impression that the liver is central to the pathophysiology of PXE/generalized arterial calcification of infancy. The emergence of inflammation as a contributor to the calcification in PXE suggested that peripheral tissues play a larger role than expected. In this study, we investigated whether bone marrow-derived ABCC6 contributes to the calcification in PXE. In Abcc6‒/‒ mice, we observed prevalent mineralization in several lymph nodes and surrounding connective tissues and an extensive network of lymphatic vessels within vibrissae, a calcified tissue in Abcc6‒/‒ mice. Furthermore, we found evidence of lymphangiogenesis in patients with PXE and mouse skin, suggesting an inflammatory process. Finally, restoring wild-type bone marrow in Abcc6‒/‒ mice produced a significant reduction of calcification, suggesting that the liver alone is not sufficient to fully inhibit mineralization. With evidence that ABCC6 is expressed in lymphocytes, we suggest that the adaptative immune system and inflammation largely contribute to the calcification in PXE/generalized arterial calcification of infancy.
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Affiliation(s)
- Christopher Brampton
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA; Bio-Rad Laboratories, Hercules, California, USA
| | - Viola Pomozi
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA; Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences Centre of Excellence, Budapest, Hungary
| | - Yannick Le Corre
- PXE National Reference Center (MAGEC Nord), University Hospital of Angers, Angers, France
| | - Janna Zoll
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Gilles Kauffenstein
- UMR INSERM 1260, Nano Regenerative Medicine, University of Strasbourg, Strasbourg, France
| | - Chi Ma
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Peter R Hoffmann
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA
| | - Ludovic Martin
- PXE National Reference Center (MAGEC Nord), University Hospital of Angers, Angers, France; CNRS 6015, UMR INSERM U1083, MITOVASC Laboratory, University of Angers, Angers, France
| | - Olivier Le Saux
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii, USA.
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Rubera I, Clotaire L, Laurain A, Destere A, Martin L, Duranton C, Leftheriotis G. A Plasma Pyrophosphate Cutoff Value for Diagnosing Pseudoxanthoma Elasticum. Int J Mol Sci 2024; 25:6502. [PMID: 38928212 PMCID: PMC11203691 DOI: 10.3390/ijms25126502] [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: 05/07/2024] [Revised: 06/03/2024] [Accepted: 06/09/2024] [Indexed: 06/28/2024] Open
Abstract
Pseudoxanthoma elasticum (PXE) is a rare inherited systemic disease responsible for a juvenile peripheral arterial calcification disease. The clinical diagnosis of PXE is only based on a complex multi-organ phenotypic score and/or genetical analysis. Reduced plasma inorganic pyrophosphate concentration [PPi]p has been linked to PXE. In this study, we used a novel and accurate method to measure [PPi]p in one of the largest cohorts of PXE patients, and we reported the valuable contribution of a cutoff value to PXE diagnosis. Plasma samples and clinical records from two French reference centers for PXE (PXE Consultation Center, Angers, and FAVA-MULTI South Competent Center, Nice) were assessed. Plasma PPi were measured in 153 PXE and 46 non-PXE patients. The PPi concentrations in the plasma samples were determined by a new method combining enzymatic and ion chromatography approaches. The best match between the sensitivity and specificity (Youden index) for diagnosing PXE was determined by ROC analysis. [PPi]p were lower in PXE patients (0.92 ± 0.30 µmol/L) than in non-PXE patients (1.61 ± 0.33 µmol/L, p < 0.0001), corresponding to a mean reduction of 43 ± 19% (SD). The PPi cutoff value for diagnosing PXE in all patients was 1.2 µmol/L, with a sensitivity of 83.3% and a specificity of 91.1% (AUC = 0.93), without sex differences. In patients aged <50 years (i.e., the age period for PXE diagnosis), the cutoff PPi was 1.2 µmol/L (sensitivity, specificity, and AUC of 93%, 96%, and 0.97, respectively). The [PPi]p shows high accuracy for diagnosing PXE; thus, quantifying plasma PPi represents the first blood assay for diagnosing PXE.
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Affiliation(s)
- Isabelle Rubera
- University Côte d’Azur, CNRS, LP2M, Labex ICST, 06107 Nice, France; (I.R.); (L.C.); (A.L.); (G.L.)
| | - Laetitia Clotaire
- University Côte d’Azur, CNRS, LP2M, Labex ICST, 06107 Nice, France; (I.R.); (L.C.); (A.L.); (G.L.)
| | - Audrey Laurain
- University Côte d’Azur, CNRS, LP2M, Labex ICST, 06107 Nice, France; (I.R.); (L.C.); (A.L.); (G.L.)
| | - Alexandre Destere
- Pharmacology Department, Nice University Hospital, 06000 Nice, France
- FAVA-MULTI South Competence Center for Rare Arterial Calcifying Disease, Nice University Hospital, 06000 Nice, France
| | - Ludovic Martin
- PXE Reference Center, MAGEC Nord, Angers University Hospital, 49000 Angers, France;
| | - Christophe Duranton
- University Côte d’Azur, CNRS, LP2M, Labex ICST, 06107 Nice, France; (I.R.); (L.C.); (A.L.); (G.L.)
| | - Georges Leftheriotis
- University Côte d’Azur, CNRS, LP2M, Labex ICST, 06107 Nice, France; (I.R.); (L.C.); (A.L.); (G.L.)
- FAVA-MULTI South Competence Center for Rare Arterial Calcifying Disease, Nice University Hospital, 06000 Nice, France
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Harmsen IM, Visseren FL, Kok M, de Jong PA, Spiering W. Plasma lipids in Pseudoxanthoma Elasticum (PXE) patients: A comparative study with population-based reference values and Non-PXE controls. ATHEROSCLEROSIS PLUS 2024; 55:5-11. [PMID: 38221909 PMCID: PMC10784135 DOI: 10.1016/j.athplu.2023.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 11/10/2023] [Accepted: 12/04/2023] [Indexed: 01/16/2024]
Abstract
Background and aims - Pseudoxanthoma elasticum (PXE) is a rare genetic disease caused by pathogenic mutations in the ABCC6 gene, resulting in low values of inorganic pyrophosphate (PPi). While low PPi is thought to contribute to arterial calcification, it remains unclear whether this fully explains premature calcification in PXE. It has been hypothesized that the ABCC6 gene could be related to dyslipidemia, which could contribute to vascular calcification seen in PXE. The aim of this study is to evaluate the relation between PXE and plasma lipid concentrations in a large cohort of PXE patients compared with reference values for the general population and compared with non-PXE controls. Methods - The plasma concentrations of total cholesterol, HDL-cholesterol, tiglycerides, and LDL-cholesterol of 312 PXE patients were compared to age- and sex-matched modeled data of the general Dutch population. Differences in median lipid levels were compared with Mann-Whitney-U test. Secondly, plasma lipid concentrations of 44 PXE patients were compared to 44 not-genetically related relatives (spouses or friends), with linear models adjusted for age, sex and BMI. Results - Total cholesterol in PXE patients was 5.6 [IQR 4.6-6.4] mmol/L versus 5.3 [IQR 4.7-6.0] mmol/L (p < 0.01) in the general population; triglycerides were 1.1 [IQR 0.9-1.7] mmol/L versus 1.0 [0.7-1.4] mmol/L (p < 0.01); HDL-c was 1.4 [IQR 1.2-1.7] mmol/L versus 1.5 [IQR 1.2-1.8] mmol/L (p = 0.03) and LDL-c was 3.3 [IQR 2.7-4.1] mmol/L versus 3.2 [IQR 2.7-3.8] mmol/L (p = 0.01). In the patient control analysis with 44 pairs and age, sex and BMI adjusted, comparison with the non-PXE controls only triglycerides were significantly different (mean difference: 0.38 (0.13-0.63)). Conclusion -The lipid profiles of PXE patients are marginally different from the general population or compared to a matched control group, but the differences are unlikely to be clinically relevant. It is therefore unlikely that plasma lipids contribute to the premature vascular calcifications in PXE patients.
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Affiliation(s)
- Iris M. Harmsen
- Department of Vascular Medicine, University Medical Centre Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Frank L.J. Visseren
- Department of Vascular Medicine, University Medical Centre Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Madeleine Kok
- Department of Radiology, University Medical Centre Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Pim A. de Jong
- Department of Radiology, University Medical Centre Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Wilko Spiering
- Department of Vascular Medicine, University Medical Centre Utrecht, Utrecht University, Utrecht, the Netherlands
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Harmsen IM, Kok M, Bartstra JW, de Jong PA, Spiering W, Foppen W. Do pseudoxanthoma elasticum patients have higher prevalence of kidney stones on computed tomography compared to hospital controls? Clin Exp Nephrol 2024; 28:75-79. [PMID: 37837579 PMCID: PMC10766656 DOI: 10.1007/s10157-023-02405-2] [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: 04/25/2023] [Accepted: 09/07/2023] [Indexed: 10/16/2023]
Abstract
BACKGROUND Pseudoxanthoma elasticum (PXE) is an autosomal recessive disease characterized by diminished inorganic plasma pyrophosphate (PPi), a strong calcification inhibitor. In addition to more typical calcification of skin, retina and arterial wall a diminished plasma PPi could lead to other ectopic calcification, such as formation of kidney stones. OBJECTIVE To compare the prevalence of kidney stones between PXE patients and hospital controls on computed tomography (CT). METHOD Low-dose CT images of PXE patients and controls were assessed by one radiologist, who was blinded for the diagnosis PXE. The number of kidney stones, and the size of the largest stone was recorded. Odds ratios (ORs) for having kidney stone were calculated using multivariable adjusted logistic regression. RESULTS Our study comprised 273 PXE patients and 125 controls. The mean age of PXE patients was 51.5 ± 15.9 years compared to 54.9 ± 14.2 in the control group (p = 0.04) and PXE patients more often were women (63 vs. 50%, p = 0.013). The prevalence of kidney stones on CT was similar: 6.9% in PXE patients, compared to 5.6% in controls (p = 0.6). In the multivariate analysis adjusting for age and sex, there was no significantly higher odds for PXE patients on having stones, compared to controls: OR 1.48 (95% CI 0.62-3.96). CONCLUSION There is no significant difference in the prevalence of incidental kidney stones on CT in PXE patients versus controls.
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Affiliation(s)
- Iris M Harmsen
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 GA, Utrecht, The Netherlands
| | - Madeleine Kok
- Department of Radiology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Jonas W Bartstra
- Department of Radiology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Pim A de Jong
- Department of Radiology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
| | - Wilko Spiering
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 GA, Utrecht, The Netherlands.
| | - Wouter Foppen
- Department of Radiology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands
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6
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Wynsberghe JV, Vanakker OM. Significance of Premature Vertebral Mineralization in Zebrafish Models in Mechanistic and Pharmaceutical Research on Hereditary Multisystem Diseases. Biomolecules 2023; 13:1621. [PMID: 38002303 PMCID: PMC10669475 DOI: 10.3390/biom13111621] [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: 09/21/2023] [Revised: 10/25/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023] Open
Abstract
Zebrafish are increasingly becoming an important model organism for studying the pathophysiological mechanisms of human diseases and investigating how these mechanisms can be effectively targeted using compounds that may open avenues to novel treatments for patients. The zebrafish skeleton has been particularly instrumental in modeling bone diseases as-contrary to other model organisms-the lower load on the skeleton of an aquatic animal enables mutants to survive to early adulthood. In this respect, the axial skeletons of zebrafish have been a good read-out for congenital spinal deformities such as scoliosis and degenerative disorders such as osteoporosis and osteoarthritis, in which aberrant mineralization in humans is reflected in the respective zebrafish models. Interestingly, there have been several reports of hereditary multisystemic diseases that do not affect the vertebral column in human patients, while the corresponding zebrafish models systematically show anomalies in mineralization and morphology of the spine as their leading or, in some cases, only phenotype. In this review, we describe such examples, highlighting the underlying mechanisms, the already-used or potential power of these models to help us understand and amend the mineralization process, and the outstanding questions on how and why this specific axial type of aberrant mineralization occurs in these disease models.
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Affiliation(s)
- Judith Van Wynsberghe
- Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Ectopic Mineralization Research Group, 9000 Ghent, Belgium
| | - Olivier M Vanakker
- Center for Medical Genetics, Ghent University Hospital, 9000 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
- Ectopic Mineralization Research Group, 9000 Ghent, Belgium
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7
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Jacobs IJ, Li Q. Novel Treatments for PXE: Targeting the Systemic and Local Drivers of Ectopic Calcification. Int J Mol Sci 2023; 24:15041. [PMID: 37894722 PMCID: PMC10606721 DOI: 10.3390/ijms242015041] [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: 09/05/2023] [Revised: 10/02/2023] [Accepted: 10/06/2023] [Indexed: 10/29/2023] Open
Abstract
Pseudoxanthoma elasticum (PXE) is a heritable multisystem ectopic calcification disorder. The gene responsible for PXE, ABCC6, encodes ABCC6, a hepatic efflux transporter regulating extracellular inorganic pyrophosphate (PPi), a potent endogenous calcification inhibitor. Recent studies demonstrated that in addition to the deficiency of plasma PPi, the activated DDR/PARP signaling in calcified tissues provides an additional possible mechanism of ectopic calcification in PXE. This study examined the effects of etidronate (ETD), a stable PPi analog, and its combination with minocycline (Mino), a potent inhibitor of DDR/PARP, on ectopic calcification in an Abcc6-/- mouse model of PXE. Abcc6-/- mice, at 4 weeks of age, before the development of ectopic calcification, were treated with ETD, Mino, or both for 18 weeks. Micro-computed tomography, histopathologic examination, and quantification of the calcium content in Abcc6-/- mice treated with both ETD and Mino revealed further reduced calcification than either treatment alone. The effects were associated with reduced serum alkaline phosphatase activity without changes in plasma PPi concentrations. These results suggest that ETD and Mino combination therapy might provide an effective therapeutic approach for PXE, a currently intractable disease.
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Affiliation(s)
- Ida Joely Jacobs
- Biomedical Sciences MS Program, Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA 19107, USA;
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
- PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Qiaoli Li
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
- PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Murcia Casas B, Carrillo Linares JL, Baquero Aranda I, Rioja Villodres J, Merino Bohórquez V, González Jiménez A, Rico Corral MÁ, Bosch R, Sánchez Chaparro MÁ, García Fernández M, Valdivielso P. Lansoprazole Increases Inorganic Pyrophosphate in Patients with Pseudoxanthoma Elasticum: A Double-Blind, Randomized, Placebo-Controlled Crossover Trial. Int J Mol Sci 2023; 24:ijms24054899. [PMID: 36902331 PMCID: PMC10003519 DOI: 10.3390/ijms24054899] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/26/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Pseudoxanthoma elasticum (PXE) is characterized by low levels of inorganic pyrophosphate (PPi) and a high activity of tissue-nonspecific alkaline phosphatase (TNAP). Lansoprazole is a partial inhibitor of TNAP. The aim was to investigate whether lansoprazole increases plasma PPi levels in subjects with PXE. We conducted a 2 × 2 randomized, double-blind, placebo-controlled crossover trial in patients with PXE. Patients were allocated 30 mg/day of lansoprazole or a placebo in two sequences of 8 weeks. The primary outcome was the differences in plasma PPi levels between the placebo and lansoprazole phases. 29 patients were included in the study. There were eight drop-outs due to the pandemic lockdown after the first visit and one due to gastric intolerance, so twenty patients completed the trial. A generalized linear mixed model was used to evaluate the effect of lansoprazole. Overall, lansoprazole increased plasma PPi levels from 0.34 ± 0.10 µM to 0.41 ± 0.16 µM (p = 0.0302), with no statistically significant changes in TNAP activity. There were no important adverse events. 30 mg/day of lansoprazole was able to significantly increase plasma PPi in patients with PXE; despite this, the study should be replicated with a large number of participants in a multicenter trial, with a clinical end point as the primary outcome.
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Affiliation(s)
- Belén Murcia Casas
- Internal Medicine Unit, Hospital Universitario Virgen de la Victoria, 29010 Málaga, Spain
| | - Juan Luis Carrillo Linares
- Internal Medicine Unit, Hospital Universitario Virgen de la Victoria, 29010 Málaga, Spain
- Instituto de Investigación Biomédica de Málaga (IBIMA), 29010 Málaga, Spain
| | - Isabel Baquero Aranda
- Ophtalmology Unit, Hospital Universitario Virgen de la Victoria, 29010 Málaga, Spain
| | - José Rioja Villodres
- Instituto de Investigación Biomédica de Málaga (IBIMA), 29010 Málaga, Spain
- Centro de Investigaciones Médico-Sanitarias (CIMES), Universidad de Málaga, 29071 Málaga, Spain
| | | | | | | | - Ricardo Bosch
- Dermatology Unit, Hospital Universitario Virgen de la Victoria, 29010 Málaga, Spain
| | - Miguel Ángel Sánchez Chaparro
- Internal Medicine Unit, Hospital Universitario Virgen de la Victoria, 29010 Málaga, Spain
- Instituto de Investigación Biomédica de Málaga (IBIMA), 29010 Málaga, Spain
- Department of Medicine and Dermatology, University of Málaga, 29016 Málaga, Spain
| | - María García Fernández
- Instituto de Investigación Biomédica de Málaga (IBIMA), 29010 Málaga, Spain
- Department of Phisiology, Universidad de Málaga, 29016 Málaga, Spain
| | - Pedro Valdivielso
- Internal Medicine Unit, Hospital Universitario Virgen de la Victoria, 29010 Málaga, Spain
- Instituto de Investigación Biomédica de Málaga (IBIMA), 29010 Málaga, Spain
- Centro de Investigaciones Médico-Sanitarias (CIMES), Universidad de Málaga, 29071 Málaga, Spain
- Department of Medicine and Dermatology, University of Málaga, 29016 Málaga, Spain
- Correspondence: ; Tel.: +34-952131615
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9
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Inorganic Pyrophosphate Plasma Levels Are Decreased in Pseudoxanthoma Elasticum Patients and Heterozygous Carriers but Do Not Correlate with the Genotype or Phenotype. J Clin Med 2023; 12:jcm12051893. [PMID: 36902680 PMCID: PMC10003929 DOI: 10.3390/jcm12051893] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 01/29/2023] [Accepted: 02/10/2023] [Indexed: 03/08/2023] Open
Abstract
Pseudoxanthoma elasticum (PXE) is a rare ectopic calcification disorder affecting soft connective tissues that is caused by biallelic ABCC6 mutations. While the underlying pathomechanisms are incompletely understood, reduced circulatory levels of inorganic pyrophosphate (PPi)-a potent mineralization inhibitor-have been reported in PXE patients and were suggested to be useful as a disease biomarker. In this study, we explored the relation between PPi, the ABCC6 genotype and the PXE phenotype. For this, we optimized and validated a PPi measurement protocol with internal calibration that can be used in a clinical setting. An analysis of 78 PXE patients, 69 heterozygous carriers and 14 control samples revealed significant differences in the measured PPi levels between all three cohorts, although there was overlap between all groups. PXE patients had a ±50% reduction in PPi levels compared to controls. Similarly, we found a ±28% reduction in carriers. PPi levels were found to correlate with age in PXE patients and carriers, independent of the ABCC6 genotype. No correlations were found between PPi levels and the Phenodex scores. Our results suggest that other factors besides PPi are at play in ectopic mineralization, which limits the use of PPi as a predictive biomarker for severity and disease progression.
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Ralph D, Levine M, Millán JL, Uitto J, Li Q. Weighing the Evidence for the Roles of Plasma Versus Local Pyrophosphate in Ectopic Calcification Disorders. J Bone Miner Res 2023; 38:457-463. [PMID: 36807615 PMCID: PMC10365072 DOI: 10.1002/jbmr.4791] [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] [Received: 12/16/2022] [Revised: 02/02/2023] [Accepted: 02/16/2023] [Indexed: 02/22/2023]
Abstract
Ectopic calcification is characterized by inappropriate deposition of calcium mineral in nonskeletal connective tissues and can cause significant morbidity and mortality, particularly when it affects the cardiovascular system. Identification of the metabolic and genetic determinants of ectopic calcification could help distinguish individuals at the greatest risk of developing these pathological calcifications and could guide development of medical interventions. Inorganic pyrophosphate (PPi ) has long been recognized as the most potent endogenous inhibitor of biomineralization. It has been intensively studied as both a marker and a potential therapeutic for ectopic calcification. Decreased extracellular concentrations of PPi have been proposed to be a unifying pathophysiological mechanism for disorders of ectopic calcification, both genetic and acquired. However, are reduced plasma concentrations of PPi a reliable predictor of ectopic calcification? This perspective article evaluates the literature in favor and against a pathophysiological role of plasma versus tissue PPi dysregulation as a determinant of, and as a biomarker for, ectopic calcification. © 2023 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Douglas Ralph
- Genetics, Genomics and Cancer Biology Ph.D. Program, Jefferson College of Life Sciences, Thomas Jefferson University, Philadelphia, PA, USA.,Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA, USA.,PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
| | - Michael Levine
- Division of Endocrinology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - José Luis Millán
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Jouni Uitto
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA, USA.,PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
| | - Qiaoli Li
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA, USA.,PXE International Center of Excellence in Research and Clinical Care, Thomas Jefferson University, Philadelphia, PA, USA
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11
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Kozák E, Bartstra JW, de Jong PA, Mali WPTM, Fülöp K, Tőkési N, Pomozi V, Risseeuw S, Norel JOV, van Leeuwen R, Váradi A, Spiering W. Plasma Level of Pyrophosphate Is Low in Pseudoxanthoma Elasticum Owing to Mutations in the ABCC6 Gene, but It Does Not Correlate with ABCC6 Genotype. J Clin Med 2023; 12:jcm12031047. [PMID: 36769695 PMCID: PMC9917606 DOI: 10.3390/jcm12031047] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/04/2023] [Accepted: 01/22/2023] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Pseudoxanthoma elasticum (PXE), a monogenic disorder resulting in calcification affecting the skin, eyes and peripheral arteries, is caused by mutations in the ABCC6 gene, and is associated with low plasma inorganic pyrophosphate (PPi). It is unknown how ABCC6 genotype affects plasma PPi. METHODS We studied the association of ABCC6 genotype (192 patients with biallelic pathogenic ABCC6 mutations) and PPi levels, and its association with the severity of arterial and ophthalmological phenotypes. ABCC6 variants were classified as truncating or non-truncating, and three groups of the 192 patients were formed: those with truncating mutations on both chromosomes (n = 121), those with two non-truncating mutations (n = 10), and a group who had one truncating and one non-truncating ABCC6 mutation (n = 61). The hypothesis formulated before this study was that there was a negative association between PPi level and disease severity. RESULTS Our findings confirm low PPi in PXE compared with healthy controls (0.53 ± 0.15 vs. 1.13 ± 0.29 µM, p < 0.01). The PPi of patients correlated with increasing age (β: 0.05 µM, 95% CI: 0.03-0.06 per 10 years) and was higher in females (0.55 ± 0.17 vs. 0.51 ± 0.13 µM in males, p = 0.03). However, no association between PPi and PXE phenotypes was found. When adjusted for age and sex, no association between PPi and ABCC6 genotype was found. CONCLUSIONS Our data suggest that the relationship between ABCC6 mutations and reduced plasma PPi may not be as direct as previously thought. PPi levels varied widely, even in patients with the same ABCC6 mutations, further suggesting a lack of direct correlation between them, even though the ABCC6 protein-mediated pathway is responsible for ~60% of this metabolite in the circulation. We discuss potential factors that may perturb the expected associations between ABCC6 genotype and PPi and between PPi and disease severity. Our findings support the argument that predictions of pathogenicity made on the basis of mutations (or on the structure of the mutated protein) could be misleading.
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Affiliation(s)
- Eszter Kozák
- Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences Center of Excellence, 1117 Budapest, Hungary
| | - Jonas W. Bartstra
- Department of Radiology, University Medical Center Utrecht, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - Pim A. de Jong
- Department of Radiology, University Medical Center Utrecht, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - Willem P. T. M. Mali
- Department of Radiology, University Medical Center Utrecht, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - Krisztina Fülöp
- Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences Center of Excellence, 1117 Budapest, Hungary
| | - Natália Tőkési
- Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences Center of Excellence, 1117 Budapest, Hungary
| | - Viola Pomozi
- Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences Center of Excellence, 1117 Budapest, Hungary
| | - Sara Risseeuw
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht University, 3584 CX Utrecht, The Netherlands
| | | | - Redmer van Leeuwen
- Department of Ophthalmology, University Medical Center Utrecht, Utrecht University, 3584 CX Utrecht, The Netherlands
| | - András Váradi
- Institute of Enzymology, Research Center for Natural Sciences, Hungarian Academy of Sciences Center of Excellence, 1117 Budapest, Hungary
| | - Wilko Spiering
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, 3584 CX Utrecht, The Netherlands
- Correspondence: ; Tel.: +31-88-7571188
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