Continuous PTH in Male Mice Causes Bone Loss Because It Induces Serum Amyloid A
| Autor: | Alexandra Goetjen, Augustus D. Mazzocca, Carol C. Pilbeam, Joseph A. Lorenzo, Sui-Pok Yee, Shilpa Choudhary, Elizabeth Santone, Douglas J. Adams, Mary Beth McCarthy |
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| Rok vydání: | 2018 |
| Předmět: |
Male
0301 basic medicine endocrine system medicine.medical_specialty Anabolism Osteoporosis Parathyroid hormone Bone resorption Mice 03 medical and health sciences Endocrinology Osteogenesis Internal medicine medicine Animals Bone Resorption Research Articles Mice Knockout Serum Amyloid A Protein biology Chemistry RANK Ligand Mesenchymal Stem Cells Osteoblast medicine.disease Resorption 030104 developmental biology medicine.anatomical_structure Parathyroid Hormone RANKL biology.protein Bone marrow hormones hormone substitutes and hormone antagonists |
| Zdroj: | Endocrinology. 159:2759-2776 |
| ISSN: | 1945-7170 |
| Popis: | Increased bone resorption is considered to explain why intermittent PTH is anabolic for bone but continuous PTH is catabolic. However, when cyclooxygenase-2 (COX2) is absent in mice, continuous PTH becomes anabolic without decreased resorption. In murine bone marrow stromal cells (BMSCs), serum amyloid A (SAA)3, induced in the hematopoietic lineage by the combination of COX2-produced prostaglandin and receptor activator of nuclear factor κB ligand (RANKL), suppresses PTH-stimulated osteoblast differentiation. To determine whether SAA3 inhibits the anabolic effects of PTH in vivo, wild-type (WT) and SAA3 knockout (KO) mice were infused with PTH. In WT mice, continuous PTH induced SAA3 and was catabolic for bone. In KO mice, PTH was anabolic, increasing trabecular bone, serum markers of bone formation, and osteogenic gene expression. In contrast, PTH increased all measurements associated with bone resorption, as well as COX2 gene expression, similarly in KO and WT mice. SAA1 and SAA2 in humans are likely to have analogous functions to SAA3 in mice. RANKL induced both SAA1 and SAA2 in human bone marrow macrophages in a COX2-dependent manner. PTH stimulated osteogenesis in human BMSCs only when COX2 or RANKL was inhibited. Addition of recombinant SAA1 or SAA2 blocked PTH-stimulated osteogenesis. In summary, SAA3 suppresses the bone formation responses but not the bone resorption responses to PTH in mice, and in the absence of SAA3, continuous PTH is anabolic. In vitro studies in human bone marrow suggest that SAA may be a target for enhancing the therapeutic effects of PTH in treating osteoporosis. |
| Databáze: | OpenAIRE |
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