High-serum phosphate and parathyroid hormone distinctly regulate bone loss and vascular calcification in experimental chronic kidney disease

• Published in: Nephrology, dialysis, transplantation Vol. 34; no. 6; pp. 934 - 941
• Main Authors: Carrillo-López, Natalia, Panizo, Sara, Alonso-Montes, Cristina, Martínez-Arias, Laura, Avello, Noelia, Sosa, Patricia, Dusso, Adriana S, Cannata-Andía, Jorge B, Naves-Díaz, Manuel
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.06.2019
• Subjects: Animals; Bone Diseases, Metabolic - blood; Bone Morphogenetic Protein 2 - metabolism; Bone Morphogenetic Proteins - metabolism; Calcitriol - blood; Calcium - blood; Calcium - metabolism; Core Binding Factor Alpha 1 Subunit - metabolism; Fibroblast Growth Factors - metabolism; Genetic Markers; Hyperphosphatemia - metabolism; Kidney - drug effects; Male; Muscle, Smooth, Vascular - metabolism; Myocytes, Smooth Muscle - metabolism; Nephrectomy; Osteogenesis - drug effects; Parathyroid Hormone - blood; Parathyroid Hormone - therapeutic use; Parathyroidectomy; Phosphates - blood; Phosphorylation; Rats; Rats, Wistar; Renal Insufficiency, Chronic - blood; Vascular Calcification - metabolism; Vitamin D3 24-Hydroxylase - metabolism; mineral metabolism; renal osteodystrophy; gene expression; parathyroidectomy; vascular calcification
• ISSN: 0931-0509; 1460-2385
• DOI: 10.1093/ndt/gfy287

Abstract Background In chronic kidney disease (CKD), increases in serum phosphate and parathyroid hormone (PTH) aggravate vascular calcification (VC) and bone loss. This study was designed to discriminate high phosphorus (HP) and PTH contribution to VC and bone loss. Methods Nephrectomized rats fed a HP diet underwent either sham operation or parathyroidectomy and PTH 1-34 supplementation to normalize serum PTH. Results In uraemic rats fed a HP diet, parathyroidectomy with serum PTH 1-34 supplementation resulted in (i) reduced aortic calcium (80%) by attenuating osteogenic differentiation (higher α-actin; reduced Runx2 and BMP2) and increasing the Wnt inhibitor Sclerostin, despite a similar degree of hyperphosphataemia, renal damage and serum Klotho; (ii) prevention of bone loss mostly by attenuating bone resorption and increases in Wnt inhibitors; and (iii) a 70% decrease in serum calcitriol levels despite significantly reduced serum Fgf23, calcium and renal 24-hydroxylase, which questions that Fgf23 is the main regulator of renal calcitriol production. Significantly, when vascular smooth muscle cells (VSMCs) were exposed exclusively to high phosphate and calcium, high PTH enhanced while low PTH attenuated calcium deposition through parathyroid hormone 1 receptor (PTH1R) signalling. Conclusions In hyperphosphataemic CKD, a defective suppression of high PTH exacerbates HP-mediated osteogenic VSMC differentiation and reduces vascular levels of anti-calcifying sclerostin.