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Ferreira CR, Kavanagh D, Oheim R, Zimmerman K, Stürznickel J, Li X, Stabach P, Rettig RL, Calderone L, MacKichan C, Wang A, Hutchinson HA, Nelson T, Tommasini SM, von Kroge S, Fiedler IA, Lester ER, Moeckel GW, Busse B, Schinke T, Carpenter TO, Levine MA, Horowitz MC, Braddock DT. Response of the ENPP1-Deficient Skeletal Phenotype to Oral Phosphate Supplementation and/or Enzyme Replacement Therapy: Comparative Studies in Humans and Mice. J Bone Miner Res 2021; 36:942-955. [PMID: 33465815 PMCID: PMC8739051 DOI: 10.1002/jbmr.4254] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 01/11/2021] [Accepted: 01/15/2021] [Indexed: 12/14/2022]
Abstract
Inactivating mutations in human ecto-nucleotide pyrophosphatase/phosphodiesterase-1 (ENPP1) may result in early-onset osteoporosis (EOOP) in haploinsufficiency and autosomal recessive hypophosphatemic rickets (ARHR2) in homozygous deficiency. ARHR2 patients are frequently treated with phosphate supplementation to ameliorate the rachitic phenotype, but elevating plasma phosphorus concentrations in ARHR2 patients may increase the risk of ectopic calcification without increasing bone mass. To assess the risks and efficacy of conventional ARHR2 therapy, we performed comprehensive evaluations of ARHR2 patients at two academic medical centers and compared their skeletal and renal phenotypes with ENPP1-deficient Enpp1asj/asj mice on an acceleration diet containing high phosphate treated with recombinant murine Enpp1-Fc. ARHR2 patients treated with conventional therapy demonstrated improvements in rickets, but all adults and one adolescent analyzed continued to exhibit low bone mineral density (BMD). In addition, conventional therapy was associated with the development of medullary nephrocalcinosis in half of the treated patients. Similar to Enpp1asj/asj mice on normal chow and to patients with mono- and biallelic ENPP1 mutations, 5-week-old Enpp1asj/asj mice on the high-phosphate diet exhibited lower trabecular bone mass, reduced cortical bone mass, and greater bone fragility. Treating the Enpp1asj/asj mice with recombinant Enpp1-Fc protein between weeks 2 and 5 normalized trabecular bone mass, normalized or improved bone biomechanical properties, and prevented the development of nephrocalcinosis and renal failure. The data suggest that conventional ARHR2 therapy does not address low BMD inherent in ENPP1 deficiency, and that ENPP1 enzyme replacement may be effective for correcting low bone mass in ARHR2 patients without increasing the risk of nephrocalcinosis. © 2021 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Carlos R Ferreira
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Dillon Kavanagh
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Ralf Oheim
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kristin Zimmerman
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Julian Stürznickel
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Xiaofeng Li
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Paul Stabach
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - R Luke Rettig
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Logan Calderone
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Colin MacKichan
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Aaron Wang
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Hunter A Hutchinson
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Tracy Nelson
- Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT, USA
| | - Steven M Tommasini
- Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT, USA
| | - Simon von Kroge
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Imke Ak Fiedler
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Ethan R Lester
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Gilbert W Moeckel
- Department of Pathology, Yale University School of Medicine, New Haven, CT, USA
| | - Björn Busse
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thorsten Schinke
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas O Carpenter
- Department of Pediatrics, Yale University School of Medicine, New Haven, CT, USA
| | - Michael A Levine
- Department of Pediatrics, University of Pennsylvania Perlman School of Medicine, Philadelphia, PA, USA.,Division of Endocrinology and Diabetes and Center for Bone Health, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Mark C Horowitz
- Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven, CT, USA
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