51
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Solomon LB, Kitchen D, Anderson PH, Yang D, Starczak Y, Kogawa M, Perilli E, Smitham PJ, Rickman MS, Thewlis D, Atkins GJ. Time dependent loss of trabecular bone in human tibial plateau fractures. J Orthop Res 2018; 36:2865-2875. [PMID: 29786151 DOI: 10.1002/jor.24057] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Accepted: 05/15/2018] [Indexed: 02/04/2023]
Abstract
We investigated if time between injury and surgery affects cancellous bone properties in patients suffering tibial plateau fractures (TPF), in terms of structural integrity and gene expression controlling bone loss. A cohort of 29 TPF, operated 1-17 days post-injury, had biopsies from the fracture and an equivalent contralateral limb site, at surgery. Samples were assessed using micro-computed tomography and real-time RT-PCR analysis for the expression of genes known to be involved in bone remodeling and fracture healing. Significant decreases in the injured vs control side were observed for bone volume fraction (BV/TV, -13.5 ± 6.0%, p = 0.011), trabecular number (Tb.N, -10.5 ± 5.9%, p = 0.041) and trabecular thickness (Tb.Th, -4.6 ± 2.5%, p = 0.033). Changes in these parameters were more evident in patients operated 5-17 days post-injury, compared to those operated in the first 4 days post-injury. A significant negative association was found between Tb.Th (r = -0.54, p < 0.01) and BV/TV (r = -0.39, p < 0.05) in relation to time post-injury in the injured limb. Both BV/TV and Tb.Th were negatively associated with expression of key molecular markers of bone resorption, CTSK, ACP5, and the ratio of RANKL:OPG mRNA. These structure/gene expression relationships did not exist in the contralateral tibial plateau of these patients. This study demonstrated that there is a significant early time-dependent bone loss in the proximal tibia after TPF. This bone loss was significantly associated with altered expression of genes typically involved in the process of osteoclastic bone resorption but possibly also bone resorption by osteocytes. The mechanism of early bone loss in such fractures should be a subject of further investigation. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2865-2875, 2018.
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Affiliation(s)
- Lucian B Solomon
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA, 5005, Australia.,Orthopaedic and Trauma Service, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia
| | - David Kitchen
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA, 5005, Australia.,Orthopaedic and Trauma Service, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia
| | - Paul H Anderson
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, 5000, Australia
| | - Dongqing Yang
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Yolandi Starczak
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Masakazu Kogawa
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Egon Perilli
- The Medical Device Research Institute, College of Science and Engineering, Flinders University, Adelaide, SA, 5001, Australia
| | - Peter J Smitham
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA, 5005, Australia.,Orthopaedic and Trauma Service, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia
| | - Mark S Rickman
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA, 5005, Australia.,Orthopaedic and Trauma Service, Royal Adelaide Hospital, Adelaide, SA, 5000, Australia
| | - Dominic Thewlis
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA, 5005, Australia
| | - Gerald J Atkins
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA, 5005, Australia
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52
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Dedic C, Hung TS, Shipley AM, Maeda A, Gardella T, Miller AL, Divieti Pajevic P, Kunkel JG, Rubinacci A. Calcium fluxes at the bone/plasma interface: Acute effects of parathyroid hormone (PTH) and targeted deletion of PTH/PTH-related peptide (PTHrP) receptor in the osteocytes. Bone 2018; 116:135-143. [PMID: 30053608 PMCID: PMC6158063 DOI: 10.1016/j.bone.2018.07.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 07/20/2018] [Accepted: 07/24/2018] [Indexed: 01/10/2023]
Abstract
Calcium ion concentration ([Ca2+]) in the systemic extracellular fluid, ECF-[Ca2+], is maintained around a genetically predetermined set-point, which combines the operational level of the kidney and bone/ECF interfaces. The ECF-[Ca2+] is maintained within a narrow oscillation range by the regulatory action of Parathyroid Hormone (PTH), Calcitonin, FGF-23, and 1,25(OH)2D3. This model implies two correction mechanisms, i.e. tubular Ca2+ reabsorption and osteoclast Ca2+ resorption. Although their alterations have an effect on the ECF-[Ca2+] maintenance, they cannot fully account for rapid correction of the continuing perturbations of plasma [Ca2+], which occur daily in life. The existence of Ca2+ fluxes at quiescent bone surfaces fulfills the role of a short-term error correction mechanism in Ca2+ homeostasis. To explore the hypothesis that PTH regulates the cell system responsible for the fast Ca2+ fluxes at the bone/ECF interface, we have performed direct real-time measurements of Ca2+ fluxes at the surface of ex-vivo metatarsal bones maintained in physiological conditions mimicking ECF, and exposed to PTH. To further characterize whether the PTH receptor on osteocytes is a critical component of the minute-to-minute ECF-[Ca2+] regulation, metatarsal bones from mice lacking the PTH receptor in these cells were tested ex vivo for rapid Ca2+ exchange. We performed direct real-time measurements of Ca2+ fluxes and concentration gradients by a scanning ion-selective electrode technique (SIET). To validate ex vivo measurements, we also evaluated acute calcemic response to PTH in vivo in mice lacking PTH receptors in osteocytes vs littermate controls. Our data demonstrated that Ca2+ fluxes at the bone-ECF interface in excised bones as well as acute calcemic response in the short-term were unaffected by PTH exposure and its signaling through its receptor in osteocytes. Rapid minute-to-minute regulation of the ECF-[Ca2+] was found to be independent of PTH actions on osteocytes. Similarly, mice lacking PTH receptor in osteocytes, responded to PTH challenge with similar calcemic increases.
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Affiliation(s)
- Christopher Dedic
- Molecular and Cell Biology, Goldman School of Dental Medicine, Boston University, Boston, MA, USA
| | - Tin Shing Hung
- Division of Life Sciences, State Key Laboratory for Molecular Neuroscience, HKUST, Hong Kong, China
| | | | - Akira Maeda
- Endocrine Unit, Massachusetts General Hospital, Boston, USA; Chugai Pharmaceutical, Japan
| | | | - Andrew L Miller
- Division of Life Sciences, State Key Laboratory for Molecular Neuroscience, HKUST, Hong Kong, China
| | - Paola Divieti Pajevic
- Molecular and Cell Biology, Goldman School of Dental Medicine, Boston University, Boston, MA, USA
| | - Joseph G Kunkel
- Pickus Center for Biomedical Research, University of New England, Biddeford, ME, USA
| | - Alessandro Rubinacci
- Bone Metabolism Unit, Division of Genetics and Cell Biology, San Raffaele Scientific Institute, Milano, Italy.
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53
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Hohman EE, Hodges JK, Wastney ME, Lachcik PJ, Han CY, Dwyer D, Peacock M, Kostenuik PJ, Weaver CM. Serum calcium concentration is maintained when bone resorption is suppressed by osteoprotegerin in young growing male rats. Bone 2018; 116:162-170. [PMID: 30077758 DOI: 10.1016/j.bone.2018.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 07/26/2018] [Accepted: 08/01/2018] [Indexed: 01/22/2023]
Abstract
Serum calcium (Ca) is maintained in a narrow range through regulation of Ca metabolism in the intestine, kidney, and bone. Calcium is incorporated and resorbed from bone during bone remodeling via cellular processes as well as by exchange. Both routes contribute to calcium homeostasis. To assess the magnitude of bone turnover contribution to calcium homeostasis we labeled bone with a Ca tracer and measured Ca release following stimulation or suppression of bone resorption. Young growing male rats (n = 162) were dosed with 45Ca to label skeletal Ca. After a one-month period to allow the label to incorporate into the skeleton, rats were treated with a bone resorption antagonist (OPG), a bone resorption agonist (RANKL), or vehicle control (PBS). Serum and urine 45Ca and total Ca, and serum TRACP5b (a bone resorption biomarker), were monitored for 45 days following treatment. Tracer data were analyzed by a compartmental model using WinSAAM to quantify dynamic changes in Ca metabolism and identify sites of change following treatment. In RANKL treated rats, both serum 45Ca and serum TRACP5b were increased by >70% due to a 25-fold increase in bone resorption. In OPG treated rats, both serum 45Ca and serum TRACP5b were suppressed by >70% due to a 75% decrease in bone resorption, a 3-fold increase in bone formation, and a 50% increase in absorption. Because TRACP5b and 45Ca responded similarly, we conclude that Ca release from bone into serum occurs mostly via osteoclast-mediated bone resorption. However, because serum Ca concentration did not change with altered resorption in response to either RANKL or OPG treatment, we also conclude that serum Ca concentration under normal dietary conditions in young growing male rats is maintained by processes in addition to cellular bone resorption.
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Affiliation(s)
- Emily E Hohman
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | - Joanna K Hodges
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | - Meryl E Wastney
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | - Pamela J Lachcik
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA
| | - Chun-Ya Han
- Metabolic Disorders Research, Amgen, Thousand Oaks, CA, USA
| | - Denise Dwyer
- Metabolic Disorders Research, Amgen, Thousand Oaks, CA, USA
| | - Munro Peacock
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Paul J Kostenuik
- Phylon Pharma Services, Newbury Park, CA, USA; University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Connie M Weaver
- Department of Nutrition Science, Purdue University, West Lafayette, IN, USA.
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54
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Alemi AS, Mazur CM, Fowler TW, Woo JJ, Knott PD, Alliston T. Glucocorticoids cause mandibular bone fragility and suppress osteocyte perilacunar-canalicular remodeling. Bone Rep 2018; 9:145-153. [PMID: 30306100 PMCID: PMC6176786 DOI: 10.1016/j.bonr.2018.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 09/06/2018] [Accepted: 09/27/2018] [Indexed: 02/06/2023] Open
Abstract
Osteocytes support dynamic, cell-intrinsic resorption and deposition of bone matrix through a process called perilacunar/canalicular remodeling (PLR). In long bones, PLR depends on MMP13 and is tightly regulated by PTH, sclerostin, TGFβ, and glucocorticoids. However, PLR is regulated differently in the cochlea, suggesting a mechanism that is anatomically distinct. Unlike long bones, the mandible derives from neural crest and exhibits unique susceptibility to medication and radiation induced osteonecrosis. Therefore, we sought to determine if PLR in the mandible is suppressed by glucocorticoids, as it is in long bone. Hemimandibles were collected from mice subcutaneously implanted with prednisolone or vehicle containing pellets for 7, 21, or 55 days (n = 8/group) for radiographic and histological analyses. Within 21 days, micro-computed tomography revealed a glucocorticoid-dependent reduction in bone volume/total volume and trabecular thickness and a significant decrease in bone mineral density after 55 days. Within 7 days, glucocorticoids strongly and persistently repressed osteocytic expression of the key PLR enzyme MMP13 in both trabecular and cortical bone of the mandible. Cathepsin K expression was significantly reduced only after 55 days of glucocorticoid treatment, at which point histological analysis revealed a glucocorticoid-dependent reduction in the lacunocanalicular surface area. In addition to reducing bone mass and suppressing PLR, glucocorticoids also reduced the stiffness of mandibular bone in flexural tests. Thus, osteocyte PLR in the neural crest-derived mandible is susceptible to glucocorticoids, just as it is in the mesodermally-derived femur, highlighting the need to further study PLR as a target of drugs, and radiation in mandibular osteonecrosis.
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Affiliation(s)
- A Sean Alemi
- Department of Otorhinolaryngology, Head and Neck Surgery, University of California San Francisco, United States of America
| | - Courtney M Mazur
- Department of Orthopaedic Surgery, University of California San Francisco, United States of America.,UC Berkeley-UCSF Graduate Program in Bioengineering, United States of America
| | - Tristan W Fowler
- Department of Orthopaedic Surgery, University of California San Francisco, United States of America
| | - Jonathon J Woo
- Department of Orthopaedic Surgery, University of California San Francisco, United States of America
| | - P Daniel Knott
- Department of Otorhinolaryngology, Head and Neck Surgery, University of California San Francisco, United States of America
| | - Tamara Alliston
- Department of Otorhinolaryngology, Head and Neck Surgery, University of California San Francisco, United States of America.,Department of Orthopaedic Surgery, University of California San Francisco, United States of America.,UC Berkeley-UCSF Graduate Program in Bioengineering, United States of America
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55
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Whitty C, Wardale RJ, Henson FM. The regulation of sclerostin by cathepsin K in periodontal ligament cells. Biochem Biophys Res Commun 2018; 503:550-555. [DOI: 10.1016/j.bbrc.2018.05.160] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 05/23/2018] [Indexed: 12/20/2022]
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56
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Iwasaki Y, Yamato H, Fukagawa M. TGF-Beta Signaling in Bone with Chronic Kidney Disease. Int J Mol Sci 2018; 19:E2352. [PMID: 30103389 PMCID: PMC6121599 DOI: 10.3390/ijms19082352] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 07/30/2018] [Accepted: 08/08/2018] [Indexed: 01/05/2023] Open
Abstract
Transforming growth factor (TGF)-β signaling is not only important in skeletal development, but also essential in bone remodeling in adult bone. The bone remodeling process involves integrated cell activities induced by multiple stimuli to balance bone resorption and bone formation. TGF-β plays a role in bone remodeling by coordinating cell activities to maintain bone homeostasis. However, mineral metabolism disturbance in chronic kidney disease (CKD) results in abnormal bone remodeling, which leads to ectopic calcification in CKD. High circulating levels of humoral factors such as parathyroid hormone, fibroblast growth factor 23, and Wnt inhibitors modulate bone remodeling in CKD. Several reports have revealed that TGF-β is involved in the production and functions of these factors in bone. TGF-β may act as a factor that mediates abnormal bone remodeling in CKD.
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Affiliation(s)
- Yoshiko Iwasaki
- Department of Health Sciences, Oita University of Nursing and Health Sciences, Oita 870-1163, Japan.
| | - Hideyuki Yamato
- Division of Nephrology and Metabolism, Tokai University School of Medicine, Kanagawa 259-119, Japan.
| | - Masafumi Fukagawa
- Division of Nephrology and Metabolism, Tokai University School of Medicine, Kanagawa 259-119, Japan.
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57
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Yajima A, Tsuchiya K, Burr DB, Minner DE, Condon KW, Miller CA, Satoh S, Inaba M, Nakayama T, Tanizawa T, Ito A, Nitta K. Osteocytic perilacunar/canalicular turnover in hemodialysis patients with high and low serum PTH levels. Bone 2018; 113:68-76. [PMID: 29738853 DOI: 10.1016/j.bone.2018.05.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 04/16/2018] [Accepted: 05/02/2018] [Indexed: 01/30/2023]
Abstract
Osteocytic perilacunar/canalicular turnover in hemodialysis patients has not yet been reported. Osteocyte lacunae in lamellar bone and woven bone were classified as eroded surface-, osteoid surface-, and quiescent surface-predominant osteocyte lacunae (ES-Lc, OS-Lc, QS-Lc, respectively) in 55 hemodialysis patients with either high- (n = 45) or low- (n = 10) parathyroid hormone levels, and 19 control subjects without chronic kidney disease. We calculated the area and number of ES-Lc, OS-Lc, and QS-Lc. The mineralized surface on the osteocyte lacunar walls was measured in each group, and compared among the three groups. The shapes of the osteocyte lacunar walls were validated by backscattered electron microscopy. While the number of ES-Lc per bone area (N.ES-Lc/B.Ar) was higher than the number of OS-Lc per bone area (N.OS-Lc/B.Ar) in all groups, N.ES-Lc/B.Ar and N.OS-Lc/B.Ar were greater in high-parathyroid hormone group than in low-parathyroid hormone and control groups. The total volume of ES-Lc per bone area (ES-Lc.Ar/B.Ar) was greater than the total volume of OS-Lc per bone area (OS-Lc.Ar/B.Ar) in both parathyroid hormone groups. However, both lacunar erosion and lacunar formation increased proportionally, suggesting that global coupling between them was maintained. N.ES-Lc/B.Ar was higher in woven bone than in lamellar bone. The rate of OS-Lc stained by tetracycline hydrochloride, the mineralized lacunar surface and the mean area of OS-Lc with Tc obtained from both parathyroid hormone groups were greater than those in the control group. We conclude that osteocytic perilacunar/canalicular turnover is increased in hemodialysis patients with high parathyroid hormone levels. Osteocytic perilacunar/canalicular turnover depends, at least in part, on serum parathyroid hormone level. However, the ideal PTH level for osteocytic perilacunar/canalicular turnover could not be determined but osteocytic osteolysis was predominant in both the high- and low-PTH groups in this study. Thus, attention should be paid to bone loss from the viewpoint of osteocytic perilacunar/canalicular turnover in hemodialysis patients.
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Affiliation(s)
- Aiji Yajima
- Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, USA; Department of Medicine, Kidney Center, Tokyo Women's Medical University, Tokyo, Japan.
| | - Ken Tsuchiya
- Department of Blood Purification, Kidney Center, Tokyo Women's Medical University, Tokyo, Japan
| | - David B Burr
- Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, USA
| | - Daniel E Minner
- Department of Integrated Nanosystems Development Institute, Indiana University, Purdue University, Indianapolis, IN, USA
| | - Keith W Condon
- Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, USA
| | - Caroline A Miller
- Department of Anatomy and Cell Biology, Indiana University, School of Medicine, Indianapolis, IN, USA
| | - Shigeru Satoh
- Center for Kidney Disease and Transplantation, Akita University Hospital, Akita, Japan
| | - Masaaki Inaba
- Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan
| | | | | | - Akemi Ito
- Ito Bone Histomorphometry Institute, Niigata, Japan
| | - Kosaku Nitta
- Department of Medicine, Kidney Center, Tokyo Women's Medical University, Tokyo, Japan
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58
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Osteocyte-Intrinsic TGF-β Signaling Regulates Bone Quality through Perilacunar/Canalicular Remodeling. Cell Rep 2018; 21:2585-2596. [PMID: 29186693 DOI: 10.1016/j.celrep.2017.10.115] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/26/2017] [Accepted: 10/29/2017] [Indexed: 02/08/2023] Open
Abstract
Poor bone quality contributes to bone fragility in diabetes, aging, and osteogenesis imperfecta. However, the mechanisms controlling bone quality are not well understood, contributing to the current lack of strategies to diagnose or treat bone quality deficits. Transforming growth factor beta (TGF-β) signaling is a crucial mechanism known to regulate the material quality of bone, but its cellular target in this regulation is unknown. Studies showing that osteocytes directly remodel their perilacunar/canalicular matrix led us to hypothesize that TGF-β controls bone quality through perilacunar/canalicular remodeling (PLR). Using inhibitors and mice with an osteocyte-intrinsic defect in TGF-β signaling (TβRIIocy-/-), we show that TGF-β regulates PLR in a cell-intrinsic manner to control bone quality. Altogether, this study emphasizes that osteocytes are key in executing the biological control of bone quality through PLR, thereby highlighting the fundamental role of osteocyte-mediated PLR in bone homeostasis and fragility.
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59
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Han Y, You X, Xing W, Zhang Z, Zou W. Paracrine and endocrine actions of bone-the functions of secretory proteins from osteoblasts, osteocytes, and osteoclasts. Bone Res 2018; 6:16. [PMID: 29844945 PMCID: PMC5967329 DOI: 10.1038/s41413-018-0019-6] [Citation(s) in RCA: 323] [Impact Index Per Article: 53.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Revised: 03/21/2018] [Accepted: 04/16/2018] [Indexed: 12/17/2022] Open
Abstract
The skeleton is a dynamic organ that is constantly remodeled. Proteins secreted from bone cells, namely osteoblasts, osteocytes, and osteoclasts exert regulation on osteoblastogenesis, osteclastogenesis, and angiogenesis in a paracrine manner. Osteoblasts secrete a range of different molecules including RANKL/OPG, M-CSF, SEMA3A, WNT5A, and WNT16 that regulate osteoclastogenesis. Osteoblasts also produce VEGFA that stimulates osteoblastogenesis and angiogenesis. Osteocytes produce sclerostin (SOST) that inhibits osteoblast differentiation and promotes osteoclast differentiation. Osteoclasts secrete factors including BMP6, CTHRC1, EFNB2, S1P, WNT10B, SEMA4D, and CT-1 that act on osteoblasts and osteocytes, and thereby influenceaA osteogenesis. Osteoclast precursors produce the angiogenic factor PDGF-BB to promote the formation of Type H vessels, which then stimulate osteoblastogenesis. Besides, the evidences over the past decades show that at least three hormones or "osteokines" from bone cells have endocrine functions. FGF23 is produced by osteoblasts and osteocytes and can regulate phosphate metabolism. Osteocalcin (OCN) secreted by osteoblasts regulates systemic glucose and energy metabolism, reproduction, and cognition. Lipocalin-2 (LCN2) is secreted by osteoblasts and can influence energy metabolism by suppressing appetite in the brain. We review the recent progresses in the paracrine and endocrine functions of the secretory proteins of osteoblasts, osteocytes, and osteoclasts, revealing connections of the skeleton with other tissues and providing added insights into the pathogenesis of degenerative diseases affecting multiple organs and the drug discovery process.
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Affiliation(s)
- Yujiao Han
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031 China
| | - Xiuling You
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031 China
| | - Wenhui Xing
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031 China
| | - Zhong Zhang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031 China
| | - Weiguo Zou
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Sciences, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031 China
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60
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Bertacchini J, Magarò MS, Potì F, Palumbo C. Osteocytes Specific GSK3 Inhibition Affects In Vitro Osteogenic Differentiation. Biomedicines 2018; 6:biomedicines6020061. [PMID: 29883388 PMCID: PMC6027076 DOI: 10.3390/biomedicines6020061] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 04/24/2018] [Accepted: 05/13/2018] [Indexed: 01/01/2023] Open
Abstract
Osteocytes, the most important regulators of bone processes, are producers of molecules (usually proteins) that act as signals in order to communicate with nearby cells. These factors control cell division (proliferation), differentiation, and survival. Substantial evidence showed different signaling pathways activated by osteocytes and involved in osteoblast differentiation, in particular in the last decade, when the Wingless-related integration site (WNT) pathway assumed a critical large importance. WNT activation by inhibiting glycogen synthase kinase 3 (GSK-3) causes bone anabolism, making GSK3 a potential therapeutic target for bone diseases. In our study, we hypothesized an important role of the osteocyte MLO-Y4 conditioned medium in controlling the differentiation process of osteoblast cell line 2T3. We found an effect of diminished differentiation capability of 2T3 upon conditioning with medium from murine long bone osteocyte-Y4 cells (MLO-Y4) pre-treated with GSK3 inhibitor CHIR2201. The novel observations of this study provide knowledge about the inhibition of GSK3 in MLO-Y4 cells. This strategy could be used as a plausible target in osteocytes in order to regulate bone resorption mediated by a loss of osteoblasts activity through a paracrine loop.
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Affiliation(s)
- Jessika Bertacchini
- Department of Biomedical, Metabolic Science and Neuroscience, University of Modena and Reggio Emilia, Via Largo del Pozzo 71, 41124 Modena, Italy.
| | - Maria Sara Magarò
- Department of Biomedical, Metabolic Science and Neuroscience, University of Modena and Reggio Emilia, Via Largo del Pozzo 71, 41124 Modena, Italy.
| | - Francesco Potì
- Unit of Neurosciences, Department of Medicine and Surgery, University of Parma, via Volturno 39/F, 43125 Parma, Italy.
| | - Carla Palumbo
- Department of Biomedical, Metabolic Science and Neuroscience, University of Modena and Reggio Emilia, Via Largo del Pozzo 71, 41124 Modena, Italy.
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61
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Liu R, Lin Y, Lin J, Zhang L, Mao X, Huang B, Xiao Y, Chen Z, Chen Z. Blood Prefabrication Subcutaneous Small Animal Model for the Evaluation of Bone Substitute Materials. ACS Biomater Sci Eng 2018; 4:2516-2527. [PMID: 33435115 DOI: 10.1021/acsbiomaterials.8b00323] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Runheng Liu
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yixiong Lin
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Jinying Lin
- Xiamen Stomatological Hospital, Xiamen 361000, China
| | - Linjun Zhang
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Xueli Mao
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Baoxin Huang
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Yin Xiao
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
- Institute of Health and Biomedical Innovation and the Australia-China Centre for Tissue Engineering and Regenerative Medicine, Queensland University of Technology, Brisbane 4059, Australia
| | - Zhuofan Chen
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
| | - Zetao Chen
- Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat-sen University and Guangdong Provincial Key Laboratory of Stomatology, Guangzhou 510055, China
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62
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Abstract
Periprosthetic joint infection (PJI) is a potentially devastating complication of orthopedic joint replacement surgery. PJI with associated osteomyelitis is particularly problematic and difficult to cure. Whether viable osteocytes, the predominant cell type in mineralized bone tissue, have a role in these infections is not clear, although their involvement might contribute to the difficulty in detecting and clearing PJI. Here, using Staphylococcus aureus, the most common pathogen in PJI, we demonstrate intracellular infection of human-osteocyte-like cells in vitro and S. aureus adaptation by forming quasi-dormant small-colony variants (SCVs). Consistent patterns of host gene expression were observed between in vitro-infected osteocyte-like cultures, an ex vivo human bone infection model, and bone samples obtained from PJI patients. Finally, we confirm S. aureus infection of osteocytes in clinical cases of PJI. Our findings are consistent with osteocyte infection being a feature of human PJI and suggest that this cell type may provide a reservoir for silent or persistent infection. We suggest that elucidating the molecular/cellular mechanism(s) of osteocyte-bacterium interactions will contribute to better understanding of PJI and osteomyelitis, improved pathogen detection, and treatment.IMPORTANCE Periprosthetic joint infections (PJIs) are increasing and are recognized as one of the most common modes of failure of joint replacements. Osteomyelitis arising from PJI is challenging to treat and difficult to cure and increases patient mortality 5-fold. Staphylococcus aureus is the most common pathogen causing PJI. PJI can have subtle symptoms and lie dormant or go undiagnosed for many years, suggesting persistent bacterial infection. Osteocytes, the major bone cell type, reside in bony caves and tunnels, the lacuno-canalicular system. We report here that S. aureus can infect and reside in human osteocytes without causing cell death both experimentally and in bone samples from patients with PJI. We demonstrate that osteocytes respond to infection by the differential regulation of a large number of genes. S. aureus adapts during intracellular infection of osteocytes by adopting the quasi-dormant small-colony variant (SCV) lifestyle, which might contribute to persistent or silent infection. Our findings shed new light on the etiology of PJI and osteomyelitis in general.
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63
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Tokarz D, Martins JS, Petit ET, Lin CP, Demay MB, Liu ES. Hormonal Regulation of Osteocyte Perilacunar and Canalicular Remodeling in the Hyp Mouse Model of X-Linked Hypophosphatemia. J Bone Miner Res 2018; 33:499-509. [PMID: 29083055 PMCID: PMC6005377 DOI: 10.1002/jbmr.3327] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 10/14/2017] [Accepted: 10/27/2017] [Indexed: 01/07/2023]
Abstract
Osteocytes remodel their surrounding perilacunar matrix and canalicular network to maintain skeletal homeostasis. Perilacunar/canalicular remodeling is also thought to play a role in determining bone quality. X-linked hypophosphatemia (XLH) is characterized by elevated serum fibroblast growth factor 23 (FGF23) levels, resulting in hypophosphatemia and decreased production of 1,25 dihydroxyvitamin D (1,25D). In addition to rickets and osteomalacia, long bones from mice with XLH (Hyp) have impaired whole-bone biomechanical integrity accompanied by increased osteocyte apoptosis. To address whether perilacunar/canalicular remodeling is altered in Hyp mice, histomorphometric analyses of tibia and 3D intravital microscopic analyses of calvaria were performed. These studies demonstrate that Hyp mice have larger osteocyte lacunae in both the tibia and calvaria, accompanied by enhanced osteocyte mRNA and protein expression of matrix metalloproteinase 13 (MMP13) and genes classically used by osteoclasts to resorb bone, such as cathepsin K (CTSK). Hyp mice also exhibit impaired canalicular organization, with a decrease in number and branching of canaliculi extending from tibial and calvarial lacunae. To determine whether improving mineral ion and hormone homeostasis attenuates the lacunocanalicular phenotype, Hyp mice were treated with 1,25D or FGF23 blocking antibody (FGF23Ab). Both therapies were shown to decrease osteocyte lacunar size and to improve canalicular organization in tibia and calvaria. 1,25D treatment of Hyp mice normalizes osteocyte expression of MMP13 and classic osteoclast markers, while FGF23Ab decreases expression of MMP13 and selected osteoclast markers. Taken together, these studies point to regulation of perilacunar/canalicular remodeling by physiologic stimuli including hypophosphatemia and 1,25D. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Danielle Tokarz
- Advanced Microscopy Program, Center for Systems Biology and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Janaina S Martins
- Harvard Medical School, Boston, MA, USA
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA
| | | | - Charles P Lin
- Advanced Microscopy Program, Center for Systems Biology and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Boston, MA, USA
| | - Marie B Demay
- Harvard Medical School, Boston, MA, USA
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA
| | - Eva S Liu
- Harvard Medical School, Boston, MA, USA
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA, USA
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64
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The temporospatial pattern of energy metabolism coordinates the interactions between the bones and other organ systems. J Oral Biosci 2018. [DOI: 10.1016/j.job.2017.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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65
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Leder BZ. Optimizing Sequential and Combined Anabolic and Antiresorptive Osteoporosis Therapy. JBMR Plus 2018; 2:62-68. [PMID: 30283892 PMCID: PMC6124202 DOI: 10.1002/jbm4.10041] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 01/31/2018] [Accepted: 02/06/2018] [Indexed: 01/22/2023] Open
Abstract
As osteoporosis therapy options have expanded, and clinical guidelines have begun to embrace the concept of limited treatment courses and “drug holidays,” the choices that physicians must make when initiating, electing to continue, or switching therapies have become more complex. As a result, one of the fundamental issues that must be carefully considered is whether, when, and in what sequence anabolic therapies should be utilized. This review evaluates the current evidence supporting the optimal sequence for the use of anabolic and antiresorptive drugs and assesses the expanding number of clinical trials favoring the initial use of anabolic therapy followed by an antiresorptive agent. This review also explores the evidence suggesting that the effectiveness of anabolic medications are diminished when used in patients that have been previously treated with specific antiresorptive drugs for prolonged periods. Finally, the recent advances in designing combination antiresorptive/anabolic treatment approaches are detailed, with a focus on combined denosumab/teriparatide regimens, which appear to provide the most substantial and clinically relevant skeletal benefits to patients with established osteoporosis. © 2018 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.
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Affiliation(s)
- Benjamin Z Leder
- Harvard Medical School Boston MA USA.,Endocrine Unit Massachusetts General Hospital Boston MA USA
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66
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Bhattacharyya S, Pal S, Chattopadhyay N. Targeted inhibition of sclerostin for post-menopausal osteoporosis therapy: A critical assessment of the mechanism of action. Eur J Pharmacol 2018; 826:39-47. [PMID: 29476877 DOI: 10.1016/j.ejphar.2018.02.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 02/15/2018] [Accepted: 02/19/2018] [Indexed: 01/01/2023]
Abstract
Promising news in the treatment of osteoporosis is that sequestering sclerostin from circulation with antibodies stimulates robust bone formation. Pre-clinical studies on rodents and monkeys have confirmed that treatment with anti-sclerostin monoclonal antibody (Scl-Ab) increases bone mass, improves bone strength and enhances fracture repair. Clinical trials show that bone gain (anabolic effect) is transient and are primarily at central (spine and hips) than peripheral (wrist) sites. Interestingly Scl-Ab also inhibited bone resorption. Thus Scl-Ab is being regarded as the pharmacologic agent with dual properties - stimulating bone formation and decreasing bone resorption. Sclerostin neutralization transiently increases bone formation markers in post-menopausal women and like parathyroid hormone (PTH) activates osteoblasts and lining cells resulting in bone anabolic effect. However, unlike PTH, sclerostin antibody also decreases bone resorption (anti-catabolic). Although, the U.S. Food and Drug Administration have accepted the Biologics License Application for one of the monoclonal antibodies against sclerostin (romosozumab) for review, many questions remain before romosozumab can be introduced as a skeletal anabolic agent to clinical practice. For example, neutralizing sclerostin alters calcium homeostasis and increases PTH. In addition, sclerostin depletion in preclinical studies has been reported to severely compromises B cell depletion in bone marrow. We have reviewed the currently available evidences that support the use of sclerostin antibody in treating osteoporosis and compare its efficacy and mechanism of action with the currently available anabolic drug, human PTH.
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Affiliation(s)
- Sharmistha Bhattacharyya
- Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow 226031, India; Women Scientist, DBT-BIO-Care, Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Subhashis Pal
- Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow 226031, India
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67
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Anagnostis P, Vakalopoulou S, Christoulas D, Paschou SA, Papatheodorou A, Garipidou V, Kokkoris P, Terpos E. The role of sclerostin/dickkopf-1 and receptor activator of nuclear factor kB ligand/osteoprotegerin signalling pathways in the development of osteoporosis in patients with haemophilia A and B: A cross-sectional study. Haemophilia 2017; 24:316-322. [PMID: 29194852 DOI: 10.1111/hae.13384] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2017] [Indexed: 12/19/2022]
Abstract
AIM Haemophilia A and B are associated with reduced bone mineral density (BMD). The aim of this study was to assess circulating sclerostin and dickkopf-1 (Dkk-1), (inhibitors of osteoblastic differentiation), as well as the receptor activator of nuclear factor kB ligand (RANKL)/osteoprotegerin (OPG) system (the major regulator of osteoclastogenesis), in patients with haemophilia (PWH), their possible correlations with clinical risk factors and the effect of ibandronate on these markers. METHODS Eighty-nine male PWH (mean age 45.9 ± 15.3 years) and 30 age-matched healthy male controls participated. BMD was assessed by DXA. Sclerostin, Dkk-1, RANKL and OPG were measured in serum of patients, controls, as well as in ten patients receiving oral ibandronate (150 mg/mo), at baseline and after 12 months. RESULTS Patients with haemophilia had lower circulating sclerostin (median ± IQR: 47.4 ± 26.93 vs 250 ± 250 pmol/L, P < .001), Dkk-1 (21.24 ± 17.18 vs 26.16 ± 15.32pg/mL, P = .04) and higher levels of RANKL (0.23 ± 0.03 vs 0.04 ± 0.03 pmol/L, P = .001), RANKL/OPG ratio (0.063 ± 0.25 vs 0.005 ± 0.11, P = .001) compared with controls. Patients with low BMD had higher OPG concentrations compared to those with normal BMD. Sclerostin and RANKL/OPG correlated positively with BMD. Patients with severe haemophilia had lower sclerostin concentrations compared with those with mild or moderate disease. The degree of arthropathy negatively correlated with sclerostin and Dkk-1 levels. PWH who received ibandronate showed a decrease in serum Dkk-1 without any significant effect on sclerostin and RANKL/OPG. CONCLUSIONS Patients with haemophilia present increased osteoclastic activity coupled with compensatory increased osteoblastic activity. Ibandronate did not affect RANKL/OPG ratio, but it decreased Dkk-1.
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Affiliation(s)
- P Anagnostis
- Haemophilia Centre of Northern Greece, 2nd Propedeutic Department of Internal Medicine, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - S Vakalopoulou
- Haemophilia Centre of Northern Greece, 2nd Propedeutic Department of Internal Medicine, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - D Christoulas
- Department of Haematology, 251 General Air Force Hospital, Athens, Greece
| | - S A Paschou
- Division of Endocrinology and Diabetes, "Aghia Sophia" Hospital, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - A Papatheodorou
- Department of Haematology, 251 General Air Force Hospital, Athens, Greece
| | - V Garipidou
- Haemophilia Centre of Northern Greece, 2nd Propedeutic Department of Internal Medicine, Hippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - P Kokkoris
- Department of Endocrinology, 251 General Air Force Hospital, Athens, Greece
| | - E Terpos
- Department of Clinical Therapeutics, School of Medicine, Alexandra General Hospital, National and Kapodistrian University of Athens, Athens, Greece
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68
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Bonnet N, Biver E, Chevalley T, Rizzoli R, Garnero P, Ferrari SL. Serum Levels of a Cathepsin-K Generated Periostin Fragment Predict Incident Low-Trauma Fractures in Postmenopausal Women Independently of BMD and FRAX. J Bone Miner Res 2017; 32:2232-2238. [PMID: 28766739 DOI: 10.1002/jbmr.3203] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/20/2017] [Accepted: 06/21/2017] [Indexed: 11/09/2022]
Abstract
Periostin is a matricellular protein involved in bone formation and bone matrix organization, but it is also produced by other tissues. Its circulating levels have been weakly associated with bone microstructure and prevalent fractures, possibly because periostin measured by the current commercial assays does not specifically reflect bone metabolism. In this context, we developed a new ELISA for a periostin fragment resulting from cathepsin K digestion (K-Postn). We hypothesized that circulating K-Postn levels could be associated with bone fragility. A total of 695 women (age 65.0 ± 1.5 years), enrolled in the Geneva Retirees Cohort (GERICO), were prospectively evaluated over 4.7 ± 1.9 years for the occurrence of low-trauma fractures. At baseline, we measured serum periostin, K-Postn, and bone turnover markers (BTMs), distal radius and tibia microstructure by HR-pQCT, hip and lumbar spine aBMD by DXA, and estimated fracture probability using the Fracture Risk Assessment Tool (FRAX). Sixty-six women sustained a low-trauma clinical fracture during the follow-up. Total periostin was not associated with fractures (HR [95% CI] per SD: 1.19 [0.89 to 1.59], p = 0.24). In contrast, K-Postn was significantly higher in the fracture versus nonfracture group (57.5 ± 36.6 ng/mL versus 42.5 ± 23.4 ng/mL, p < 0.001) and associated with fracture risk (HR [95%CI] per SD: 2.14 [1.54 to 2.97], p < 0.001). After adjustment for aBMD, FRAX, bone microstructure, or BTMs, K-Postn remained significantly associated with fracture risk. The performance of the fracture prediction models was improved by adding K-Postn to aBMD or FRAX (Harrell C index for fracture: 0.70 for aBMD + K-Post versus 0.58 for aBMD alone, p = 0.001; 0.73 for FRAX + K-Postn versus 0.65 for FRAX alone, p = 0.005). Circulating K-Postn predicts incident fractures independently of BMD, BTMs, and FRAX in postmenopausal women. Hence measurement of a periostin fragment resulting from in vivo cathepsin K digestion may help to identify subjects at high risk of fracture. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Nicolas Bonnet
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva, Switzerland
| | - Emmanuel Biver
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva, Switzerland
| | - Thierry Chevalley
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva, Switzerland
| | - René Rizzoli
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva, Switzerland
| | - Patrick Garnero
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva, Switzerland
| | - Serge L Ferrari
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva, Switzerland
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69
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Synergistic acceleration of experimental tooth movement by supplementary high-frequency vibration applied with a static force in rats. Sci Rep 2017; 7:13969. [PMID: 29070874 PMCID: PMC5656656 DOI: 10.1038/s41598-017-13541-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/25/2017] [Indexed: 01/29/2023] Open
Abstract
Several recent prospective clinical trials have investigated the effect of supplementary vibration applied with fixed appliances in an attempt to accelerate tooth movement and shorten the duration of orthodontic treatment. Among them, some studies reported an increase in the rate of tooth movement, but others did not. This technique is still controversial, and the underlying cellular and molecular mechanisms remain unclear. In the present study, we developed a new vibration device for a tooth movement model in rats, and investigated the efficacy and safety of the device when used with fixed appliances. The most effective level of supplementary vibration to accelerate tooth movement stimulated by a continuous static force was 3 gf at 70 Hz for 3 minutes once a week. Furthermore, at this optimum-magnitude, high-frequency vibration could synergistically enhance osteoclastogenesis and osteoclast function via NF-κB activation, leading to alveolar bone resorption and finally, accelerated tooth movement, but only when a static force was continuously applied to the teeth. These findings contribute to a better understanding of the mechanism by which optimum-magnitude high-frequency vibration accelerates tooth movement, and may lead to novel approaches for the safe and effective treatment of malocclusion.
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70
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Kogawa M, Khalid KA, Wijenayaka AR, Ormsby RT, Evdokiou A, Anderson PH, Findlay DM, Atkins GJ. Recombinant sclerostin antagonizes effects of ex vivo mechanical loading in trabecular bone and increases osteocyte lacunar size. Am J Physiol Cell Physiol 2017; 314:C53-C61. [PMID: 28978523 DOI: 10.1152/ajpcell.00175.2017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sclerostin has emerged as an important regulator of bone mass. We have shown that sclerostin can act by targeting late osteoblasts/osteocytes to inhibit bone mineralization and to upregulate osteocyte expression of catabolic factors, resulting in osteocytic osteolysis. Here we sought to examine the effect of exogenous sclerostin on osteocytes in trabecular bone mechanically loaded ex vivo. Bovine trabecular bone cores, with bone marrow removed, were inserted into individual chambers and subjected to daily episodes of dynamic loading. Cores were perfused with either osteogenic media alone or media containing human recombinant sclerostin (rhSCL) (50 ng/ml). Loaded control bone increased in apparent stiffness over time compared with unloaded bone, and this was abrogated in the presence of rhSCL. Loaded bone showed an increase in calcein uptake as a surrogate of mineral accretion, compared with unloaded bone, in which this was substantially inhibited by rhSCL treatment. Sclerostin treatment induced a significant increase in the ionized calcium concentration in the perfusate and the release of β-CTX at several time points, an increased mean osteocyte lacunar size, indicative of osteocytic osteolysis, and the expression of catabolism-related genes. Human primary osteocyte-like cultures treated with rhSCL also released β-CTX from their matrix. These results suggest that osteocytes contribute directly to bone mineral accretion, and to the mechanical properties of bone. Moreover, it appears that sclerostin, acting on osteocytes, can negate this effect by modulating the dimensions of the lacunocanalicular porosity and the composition of the periosteocyte matrix.
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Affiliation(s)
- M Kogawa
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, University of Adelaide , Adelaide, South Australia , Australia
| | - K A Khalid
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, University of Adelaide , Adelaide, South Australia , Australia
| | - A R Wijenayaka
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, University of Adelaide , Adelaide, South Australia , Australia
| | - R T Ormsby
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, University of Adelaide , Adelaide, South Australia , Australia
| | - A Evdokiou
- Discipline of Surgery, Breast Cancer Research Unit, Basil Hetzel Institute, University of Adelaide, Woodville, South Australia, Australia
| | - P H Anderson
- School of Pharmacy and Medical Sciences, University of South Australia , Adelaide, South Australia , Australia
| | - D M Findlay
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, University of Adelaide , Adelaide, South Australia , Australia
| | - G J Atkins
- Biomedical Orthopaedic Research Group, Centre for Orthopaedic and Trauma Research, University of Adelaide , Adelaide, South Australia , Australia
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71
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Abstract
PURPOSE OF REVIEW This review assembles recent understanding of the profound loss of muscle and bone in spinal cord injury (SCI). It is important to try to understand these changes, and the context in which they occur, because of their impact on the wellbeing of SC-injured individuals, and the urgent need for viable preventative therapies. RECENT FINDINGS Recent research provides new understanding of the effects of age and systemic factors on the response of bone to loading, of relevance to attempts to provide load therapy for bone in SCI. The rapidly growing dataset describing the biochemical crosstalk between bone and muscle, and the cell and molecular biology of myokines signalling to bone and osteokines regulating muscle metabolism and mass, is reviewed. The ways in which this crosstalk may be altered in SCI is summarised. Therapeutic approaches to the catabolic changes in muscle and bone in SCI require a holistic understanding of their unique mechanical and biochemical context.
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Affiliation(s)
- Jillian M Clark
- Discipline of Orthopaedics and Trauma, The University of Adelaide, North Terrace, Adelaide, South Australia, 5000, Australia.
| | - David M Findlay
- Discipline of Orthopaedics and Trauma, The University of Adelaide, North Terrace, Adelaide, South Australia, 5000, Australia
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72
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Shi C, Uda Y, Dedic C, Azab E, Sun N, Hussein AI, Petty CA, Fulzele K, Mitterberger-Vogt MC, Zwerschke W, Pereira R, Wang K, Pajevic PD. Carbonic anhydrase III protects osteocytes from oxidative stress. FASEB J 2017; 32:440-452. [PMID: 28928248 DOI: 10.1096/fj.201700485rr] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 09/05/2017] [Indexed: 12/26/2022]
Abstract
Osteocytes are master orchestrators of bone remodeling; they control osteoblast and osteoclast activities both directly via cell-to-cell communication and indirectly via secreted factors, and they are the main postnatal source of sclerostin and RANKL (receptor activator of NF-kB ligand), two regulators of osteoblast and osteoclast function. Despite progress in understanding osteocyte biology and function, much remains to be elucidated. Recently developed osteocytic cell lines-together with new genome editing tools-has allowed a closer look at the biology and molecular makeup of these cells. By using single-cell cloning, we identified genes that are associated with high Sost/sclerostin expression and analyzed their regulation and function. Unbiased transcriptome analysis of high- vs. low-Sost/sclerostin-expressing cells identified known and novel genes. Dmp1 (dentin matrix protein 1), Dkk1 (Dickkopf WNT signaling pathway inhibitor 1), and Phex were among the most up-regulated known genes, whereas Srpx2, Cd200, and carbonic anhydrase III (CAIII) were identified as novel markers of differentiated osteocytes. Aspn, Enpp2, Robo2, Nov, and Serpina3g were among the transcripts that were most significantly suppressed in high-Sost cells. Considering that CAII was recently identified as being regulated by Sost/sclerostin and capable of controlling mineral homeostasis, we focused our attention on CAIII. Here, we report that CAIII is highly expressed in osteocytes, is regulated by parathyroid hormone both in vitro and in vivo, and protects osteocytes from oxidative stress.-Shi, C., Uda, Y., Dedic, C., Azab, E., Sun, N., Hussein, A. I., Petty, C. A., Fulzele, K., Mitterberger-Vogt, M. C., Zwerschke, W., Pereira, R., Wang, K., Divieti Pajevic, P. Carbonic anhydrase III protects osteocytes from oxidative stress.
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Affiliation(s)
- Chao Shi
- Department of Orthopaedics, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.,Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Yuhei Uda
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Christopher Dedic
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Ehab Azab
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Ningyuan Sun
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Amira I Hussein
- Department of Orthopedics, School of Medicine, Boston University, Boston, Massachusetts, USA
| | - Christopher A Petty
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | - Keertik Fulzele
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA
| | | | - Werner Zwerschke
- Cell Metabolism and Differentiation Research Group, University of Innsbruck, Innsbruck, Austria
| | - Renata Pereira
- David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California, USA
| | - Kunzheng Wang
- Department of Orthopaedics, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China;
| | - Paola Divieti Pajevic
- Molecular and Cell Biology, Henry M. Goldman School of Dental Medicine, Boston University, Boston, Massachusetts, USA;
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73
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Pflanz D, Birkhold AI, Albiol L, Thiele T, Julien C, Seliger A, Thomson E, Kramer I, Kneissel M, Duda GN, Kornak U, Checa S, Willie BM. Sost deficiency led to a greater cortical bone formation response to mechanical loading and altered gene expression. Sci Rep 2017; 7:9435. [PMID: 28842678 PMCID: PMC5572735 DOI: 10.1038/s41598-017-09653-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 07/26/2017] [Indexed: 11/09/2022] Open
Abstract
Bone adaptation optimizes mass and structure, but the mechano-response is already reduced at maturation. Downregulation of sclerostin was believed to be a mandatory step in mechano-adaptation, but in young mice it was shown that load-induced formation can occur independent of sclerostin, a product of the Sost gene. We hypothesized that the bone formation and resorption response to loading is not affected by Sost deficiency, but is age-specific. Our findings indicate that the anabolic response to in vivo tibial loading was reduced at maturation in Sost Knockout (KO) and littermate control (LC) mice. Age affected all anabolic and catabolic parameters and altered Sost and Wnt target gene expression. While load-induced cortical resorption was similar between genotypes, loading-induced gains in mineralizing surface was enhanced in Sost KO compared to LC mice. Loading led to a downregulation in expression of the Wnt inhibitor Dkk1. Expression of Dkk1 was greater in both control and loaded limbs of Sost KO compared to LC mice suggesting a compensatory role in the absence of Sost. These data suggest physical activity could enhance bone mass concurrently with sclerostin-neutralizing antibodies, but treatment strategies should consider the influence of age on ultimate load-induced bone mass gains.
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Affiliation(s)
- David Pflanz
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Annette I Birkhold
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Continuum Biomechanics and Mechanobiology Research Group, Institute of Applied Mechanics, University of Stuttgart, Stuttgart, Germany
| | - Laia Albiol
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Berlin-Brandenburg School for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Tobias Thiele
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Catherine Julien
- Research Centre, Shriners Hospital for Children-Canada, Department of Pediatric Surgery, McGill University, Montreal, Canada
| | - Anne Seliger
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Erin Thomson
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Ina Kramer
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | | | - Georg N Duda
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Berlin-Brandenburg School for Regenerative Therapies, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Uwe Kornak
- Institute for Medical Genetics and Human Genetics, Charité- Universitätsmedizin Berlin, Berlin, Germany.,Berlin-Brandenburg Center for Regenerative Therapies, Charité-Universitätsmedizin Berlin, Berlin, Germany.,Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Sara Checa
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Bettina M Willie
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Berlin, Germany. .,Research Centre, Shriners Hospital for Children-Canada, Department of Pediatric Surgery, McGill University, Montreal, Canada.
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74
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Jähn K, Kelkar S, Zhao H, Xie Y, Tiede-Lewis LM, Dusevich V, Dallas SL, Bonewald LF. Osteocytes Acidify Their Microenvironment in Response to PTHrP In Vitro and in Lactating Mice In Vivo. J Bone Miner Res 2017; 32:1761-1772. [PMID: 28470757 PMCID: PMC5550338 DOI: 10.1002/jbmr.3167] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 04/04/2017] [Accepted: 05/01/2017] [Indexed: 11/10/2022]
Abstract
Osteocytes appear to mobilize calcium within minutes in response to PTH injections; we have previously shown that osteocytes remove their perilacunar matrix during lactation through activation of the PTH type 1 receptor. Mechanisms utilized by osteocytes to mobilize calcium are unknown but we hypothesized that the molecular components may be similar to those used by osteoclasts. Here we show, using IDG-SW3 cells that ATP6V0D2, an essential component of vacuolar ATPase in osteoclasts, and other genes associated with osteoclastic bone resorption, increase with osteoblast to osteocyte differentiation. Furthermore, PTHrP increases ATP6V0D2 expression and induces proton generation by primary osteocytes, which is blocked by bafilomycin, a vacuolar ATPase inhibitor. These in vitro proton measurements raised the question of osteocyte viability in an acidic environment. Interestingly, osteocytes, showed enhanced viability at pH as low as 5 compared to osteoblasts and fibroblasts in vitro. To study in vivo acidification by osteocytes, virgin and lactating CD1 mice on a low calcium diet were injected with the pH indicator dye, acridine orange, and their osteocyte lacuno-canalicular system imaged by confocal microscopy. Lower pH was observed in lactating compared to virgin animals. In addition, a novel transgenic mouse line with a topaz variant of green fluorescent protein (GFPtpz)-tagged collagen α2(I) chain was used. Instead of the expected reduction in GFP-fluorescence only in the perilacunar matrix, reduced fluorescence was observed in the entire bone matrix of lactating mice. Based on our experiments showing quenching of GFP in vitro, we propose that the observed reduction in GFP fluorescence in lactating mice is due to quenching of GFP by the acidic pH generated by osteocytes. Together these findings provide novel mechanistic insight into how osteocytes remove calcium from their perilacunar/pericanalicular matrices through active acidification of their microenvironment and show that osteocytes, like osteoclasts, are resistant to the negative effects of acid on viability. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Katharina Jähn
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Shilpa Kelkar
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Hong Zhao
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Yixia Xie
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - LeAnn M Tiede-Lewis
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Vladimir Dusevich
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Sarah L Dallas
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
| | - Lynda F Bonewald
- Department of Oral and Craniofacial Biology, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA
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75
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Bonnet N, Brun J, Rousseau JC, Duong LT, Ferrari SL. Cathepsin K Controls Cortical Bone Formation by Degrading Periostin. J Bone Miner Res 2017; 32:1432-1441. [PMID: 28322464 DOI: 10.1002/jbmr.3136] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 03/17/2017] [Accepted: 03/17/2017] [Indexed: 11/12/2022]
Abstract
Although inhibitors of bone resorption concomitantly reduce bone formation because of the coupling between osteoclasts and osteoblasts, inhibition or deletion of cathepsin k (CatK) stimulates bone formation despite decreasing resorption. The molecular mechanisms responsible for this increase in bone formation, particularly at periosteal surfaces where osteoclasts are relatively poor, remain unclear. Here we show that CatK pharmacological inhibition or deletion (Ctsk-/- mice) potentiates mechanotransduction signals mediating cortical bone formation. We identify periostin (Postn) as a direct molecular target for degradation by CatK and show that CatK deletion increases Postn and β-catenin expression in vivo, particularly at the periosteum. In turn, Postn deletion selectively abolishes cortical, but not trabecular, bone formation in CatK-deficient mice. Taken together, these data indicate that CatK not only plays a major role in bone remodeling but also modulates modeling-based cortical bone formation by degrading periostin and thereby moderating Wnt-β-catenin signaling. These findings provide novel insights into the role of CatK on bone homeostasis and the mechanisms of increased cortical bone volume with CatK mutations and pharmacological inhibitors. © 2017 American Society for Bone and Mineral Research.
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Affiliation(s)
- Nicolas Bonnet
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva, Switzerland
| | - Julia Brun
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva, Switzerland
| | | | - Le T Duong
- Department of Bone Biology, Merck & Co., Kenilworth, NJ, USA
| | - Serge L Ferrari
- Division of Bone Diseases, Department of Internal Medicine Specialties, Geneva University Hospital & Faculty of Medicine, Geneva, Switzerland
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76
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Halling Linder C, Ek-Rylander B, Krumpel M, Norgård M, Narisawa S, Millán JL, Andersson G, Magnusson P. Bone Alkaline Phosphatase and Tartrate-Resistant Acid Phosphatase: Potential Co-regulators of Bone Mineralization. Calcif Tissue Int 2017; 101:92-101. [PMID: 28303318 PMCID: PMC5486932 DOI: 10.1007/s00223-017-0259-2] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 02/17/2017] [Indexed: 12/18/2022]
Abstract
Phosphorylated osteopontin (OPN) inhibits hydroxyapatite crystal formation and growth, and bone alkaline phosphatase (BALP) promotes extracellular mineralization via the release of inorganic phosphate from the mineralization inhibitor inorganic pyrophosphate (PPi). Tartrate-resistant acid phosphatase (TRAP), produced by osteoclasts, osteoblasts, and osteocytes, exhibits potent phosphatase activity towards OPN; however, its potential capacity as a regulator of mineralization has not previously been addressed. We compared the efficiency of BALP and TRAP towards the endogenous substrates for BALP, i.e., PPi and pyridoxal 5'-phosphate (PLP), and their impact on mineralization in vitro via dephosphorylation of bovine milk OPN. TRAP showed higher phosphatase activity towards phosphorylated OPN and PPi compared to BALP, whereas the activity of TRAP and BALP towards PLP was comparable. Bovine milk OPN could be completely dephosphorylated by TRAP, liberating all its 28 phosphates, whereas BALP dephosphorylated at most 10 phosphates. OPN, dephosphorylated by either BALP or TRAP, showed a partially or completely attenuated phosphorylation-dependent inhibitory capacity, respectively, compared to native OPN on the formation of mineralized nodules. Thus, there are phosphorylations in OPN important for inhibition of mineralization that are removed by TRAP but not by BALP. In conclusion, our data indicate that both BALP and TRAP can alleviate the inhibitory effect of OPN on mineralization, suggesting a potential role for TRAP in skeletal mineralization. Further studies are warranted to explore the possible physiological relevance of TRAP in bone mineralization.
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Affiliation(s)
- Cecilia Halling Linder
- Department of Clinical Chemistry and Department of Clinical and Experimental Medicine, Linköping University, 581 85, Linköping, Sweden
| | - Barbro Ek-Rylander
- Division of Pathology, Department of Laboratory Medicine, Karolinska Institutet, 141 86, Huddinge, Sweden
| | - Michael Krumpel
- Division of Pathology, Department of Laboratory Medicine, Karolinska Institutet, 141 86, Huddinge, Sweden
| | - Maria Norgård
- Division of Pathology, Department of Laboratory Medicine, Karolinska Institutet, 141 86, Huddinge, Sweden
| | - Sonoko Narisawa
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - José Luis Millán
- Sanford Children's Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Göran Andersson
- Division of Pathology, Department of Laboratory Medicine, Karolinska Institutet, 141 86, Huddinge, Sweden
| | - Per Magnusson
- Department of Clinical Chemistry and Department of Clinical and Experimental Medicine, Linköping University, 581 85, Linköping, Sweden.
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77
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Kaya S, Basta-Pljakic J, Seref-Ferlengez Z, Majeska RJ, Cardoso L, Bromage T, Zhang Q, Flach CR, Mendelsohn R, Yakar S, Fritton SP, Schaffler MB. Lactation-Induced Changes in the Volume of Osteocyte Lacunar-Canalicular Space Alter Mechanical Properties in Cortical Bone Tissue. J Bone Miner Res 2017; 32:688-697. [PMID: 27859586 PMCID: PMC5395324 DOI: 10.1002/jbmr.3044] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/27/2016] [Accepted: 11/15/2016] [Indexed: 01/23/2023]
Abstract
Osteocytes can remove and remodel small amounts of their surrounding bone matrix through osteocytic osteolysis, which results in increased volume occupied by lacunar and canalicular space (LCS). It is well established that cortical bone stiffness and strength are strongly and inversely correlated with vascular porosity, but whether changes in LCS volume caused by osteocytic osteolysis are large enough to affect bone mechanical properties is not known. In the current studies we tested the hypotheses that (1) lactation and postlactation recovery in mice alter the elastic modulus of bone tissue, and (2) such local changes in mechanical properties are related predominantly to alterations in lacunar and canalicular volume rather than bone matrix composition. Mechanical testing was performed using microindentation to measure modulus in regions containing solely osteocytes and no vascular porosity. Lactation caused a significant (∼13%) reduction in bone tissue-level elastic modulus (p < 0.001). After 1 week postweaning (recovery), bone modulus levels returned to control levels and did not change further after 4 weeks of recovery. LCS porosity tracked inversely with changes in cortical bone modulus. Lacunar and canalicular void space increased 7% and 15% with lactation, respectively (p < 0.05), then returned to control levels at 1 week after weaning. Neither bone mineralization (assessed by high-resolution backscattered scanning electron microscopy) nor mineral/matrix ratio or crystallinity (assessed by Raman microspectroscopy) changed with lactation. Thus, changes in bone mechanical properties induced by lactation and recovery appear to depend predominantly on changes in osteocyte LCS dimensions. Moreover, this study demonstrates that tissue-level cortical bone mechanical properties are rapidly and reversibly modulated by osteocytes in response to physiological challenge. These data point to a hitherto unappreciated role for osteocytes in modulating and maintaining local bone mechanical properties. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Serra Kaya
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Jelena Basta-Pljakic
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | | | - Robert J Majeska
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Luis Cardoso
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Timothy Bromage
- Department of Biomaterials, New York University College of Dentistry, New York, NY, USA
| | - Qihong Zhang
- Department of Chemistry, Rutgers University, Newark, NJ, USA
| | - Carol R Flach
- Department of Chemistry, Rutgers University, Newark, NJ, USA
| | | | - Shoshana Yakar
- Department of Basic Science, New York University College of Dentistry, New York, NY, USA
| | - Susannah P Fritton
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
| | - Mitchell B Schaffler
- Department of Biomedical Engineering, City College of New York, New York, NY, USA
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78
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Fowler TW, Acevedo C, Mazur CM, Hall-Glenn F, Fields AJ, Bale HA, Ritchie RO, Lotz JC, Vail TP, Alliston T. Glucocorticoid suppression of osteocyte perilacunar remodeling is associated with subchondral bone degeneration in osteonecrosis. Sci Rep 2017; 7:44618. [PMID: 28327602 PMCID: PMC5361115 DOI: 10.1038/srep44618] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 02/10/2017] [Indexed: 11/09/2022] Open
Abstract
Through a process called perilacunar remodeling, bone-embedded osteocytes dynamically resorb and replace the surrounding perilacunar bone matrix to maintain mineral homeostasis. The vital canalicular networks required for osteocyte nourishment and communication, as well as the exquisitely organized bone extracellular matrix, also depend upon perilacunar remodeling. Nonetheless, many questions remain about the regulation of perilacunar remodeling and its role in skeletal disease. Here, we find that suppression of osteocyte-driven perilacunar remodeling, a fundamental cellular mechanism, plays a critical role in the glucocorticoid-induced osteonecrosis. In glucocorticoid-treated mice, we find that glucocorticoids coordinately suppress expression of several proteases required for perilacunar remodeling while causing degeneration of the osteocyte lacunocanalicular network, collagen disorganization, and matrix hypermineralization; all of which are apparent in human osteonecrotic lesions. Thus, osteocyte-mediated perilacunar remodeling maintains bone homeostasis, is dysregulated in skeletal disease, and may represent an attractive therapeutic target for the treatment of osteonecrosis.
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Affiliation(s)
- Tristan W Fowler
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Claire Acevedo
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, CA, USA.,Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Courtney M Mazur
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, CA, USA.,UC Berkeley-UCSF Graduate Program in Bioengineering, University of California Berkeley, Berkeley, CA, USA
| | - Faith Hall-Glenn
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Aaron J Fields
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Hrishikesh A Bale
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Robert O Ritchie
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.,Department of Materials Science and Engineering, University of California Berkeley, Berkeley, CA, USA
| | - Jeffrey C Lotz
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, CA, USA.,UC Berkeley-UCSF Graduate Program in Bioengineering, University of California Berkeley, Berkeley, CA, USA
| | - Thomas P Vail
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, CA, USA
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California San Francisco, San Francisco, CA, USA.,UC Berkeley-UCSF Graduate Program in Bioengineering, University of California Berkeley, Berkeley, CA, USA
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79
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Galea GL, Lanyon LE, Price JS. Sclerostin's role in bone's adaptive response to mechanical loading. Bone 2017; 96:38-44. [PMID: 27742499 PMCID: PMC5340132 DOI: 10.1016/j.bone.2016.10.008] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 09/27/2016] [Accepted: 10/10/2016] [Indexed: 01/08/2023]
Abstract
Mechanical loading is the primary functional determinant of bone mass and architecture, and osteocytes play a key role in translating mechanical signals into (re)modelling responses. Although the precise mechanisms remain unclear, Wnt signalling pathway components, and the anti-osteogenic canonical Wnt inhibitor Sost/sclerostin in particular, play an important role in regulating bone's adaptive response to loading. Increases in loading-engendered strains down-regulate osteocyte sclerostin expression, whereas reduced strains, as in disuse, are associated with increased sclerostin production and bone loss. However, while sclerostin up-regulation appears to be necessary for the loss of bone with disuse, the role of sclerostin in the osteogenic response to loading is more complex. While mice unable to down-regulate sclerostin do not gain bone with loading, Sost knockout mice have an enhanced osteogenic response to loading. The molecular mechanisms by which osteocytes sense and transduce loading-related stimuli into changes in sclerostin expression remain unclear but include several, potentially interlinked, signalling cascades involving periostin/integrin, prostaglandin, estrogen receptor, calcium/NO and Igf signalling. Deciphering the mechanisms by which changes in the mechanical environment regulate sclerostin production may lead to the development of therapeutic strategies that can reverse the skeletal structural deterioration characteristic of disuse and age-related osteoporosis and enhance bones' functional adaptation to loading. By enhancing the osteogenic potential of the context in which individual therapies such as sclerostin antibodies act it may become possible to both prevent and reverse the age-related skeletal structural deterioration characteristic of osteoporosis.
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Affiliation(s)
- Gabriel L Galea
- Newlife Birth Defects Research Centre, Institute of Child Health, University College London, London WC1N 1EH, United Kingdom; School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol BS40 5DU, United Kingdom.
| | - Lance E Lanyon
- School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol BS40 5DU, United Kingdom
| | - Joanna S Price
- School of Veterinary Sciences, University of Bristol, Langford House, Langford, Bristol BS40 5DU, United Kingdom
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80
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Yang D, Anderson PH, Turner AG, Morris HA, Atkins GJ. Comparison of the biological effects of exogenous and endogenous 1,25-dihydroxyvitamin D 3 on the mature osteoblast cell line MLO-A5. J Steroid Biochem Mol Biol 2016; 164:374-378. [PMID: 26949105 DOI: 10.1016/j.jsbmb.2016.03.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 02/29/2016] [Accepted: 03/01/2016] [Indexed: 10/22/2022]
Abstract
Clinical and animal data indicate that serum 25-hydroxyvitamin D3 (25D) exerts an anabolic effect on bone while serum 1α,25-dihydroxyvitamin D3 (1,25D) stimulates bone mineral loss, although the mechanism responsible for these divergent actions is unknown. Biological effects of 25D on bone cells are dependent on the local conversion to 1,25D by the 25-hydroxyvitamin D-1α-hydroxylase enzyme, CYP27B1. Therefore, identification of possible differential activities of locally produced and exogenously supplied 1,25D in bone is likely to be informative for guiding optimal administration of vitamin D supplements for bone health. The mature osteoblastic cell line MLO-A5 expresses both the vitamin D receptor (Vdr) and Cyp27b1, and therefore is a suitable model for comparing the activities of 1,25D arising from these sources. Biologically, exogenous and endogenous sources of 1,25D have similar effects on proliferation, mineralisation and induction of a range of genes by MLO-A5 osteoblasts under osteogenic conditions although endogenous 1,25D levels are markedly lower than exogenous levels. Significant differences of pharmacokinetics and pharmacodynamics of 1,25D are evident between these two sources particularly in terms of modulating gene expression for Cyp24a1 and other genes largely expressed by embedded osteoblasts/osteocytes suggesting that endogenously synthesised 1,25D is more efficiently utilised by the differentiating osteoblast.
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Affiliation(s)
- Dongqing Yang
- Bone Cell Biology Group, Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA 5005, Australia; Discipline of Medicine, University of Adelaide, Adelaide, SA 5005, Australia.
| | - Paul H Anderson
- Discipline of Medicine, University of Adelaide, Adelaide, SA 5005, Australia; Musculoskeletal Biology Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Andrew G Turner
- Discipline of Medicine, University of Adelaide, Adelaide, SA 5005, Australia; Musculoskeletal Biology Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Howard A Morris
- Discipline of Medicine, University of Adelaide, Adelaide, SA 5005, Australia; Endocrine Bone Research, Chemical Pathology, SA Pathology, Adelaide, SA 5000, Australia; Musculoskeletal Biology Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Gerald J Atkins
- Bone Cell Biology Group, Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA 5005, Australia
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81
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Wijenayaka AR, Prideaux M, Yang D, Morris HA, Findlay DM, Anderson PH, Atkins GJ. Early response of the human SOST gene to stimulation by 1α,25-dihydroxyvitamin D 3. J Steroid Biochem Mol Biol 2016; 164:369-373. [PMID: 26690786 DOI: 10.1016/j.jsbmb.2015.12.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 11/24/2015] [Accepted: 12/07/2015] [Indexed: 11/30/2022]
Abstract
The osteocyte expressed gene SOST encodes sclerostin, a potent negative regulator of bone formation and inducer of bone resorption. We have recently demonstrated that the human SOST gene is positively regulated in response to 1α,25-dihydroxyvitamin D3 (1,25D). Responsiveness may be mediated at least in part by a single classical DR3-type vitamin D response element (VDRE). In this study we examined the early responsiveness of the SOST gene to both 1,25D and to parathyroid hormone (PTH), a known repressor of SOST expression, in SaOS2 cells differentiated to an osteocyte-like stage of cell maturation. Both SOST mRNA levels and sclerostin protein levels increased in these cultures as early as 3h post-treatment with 1,25D and declined in response to PTH in the same timeframe. For 1,25D, the level of induced SOST appeared dependent on the extent, to which the degradative enzyme 1,25-dihydroxyvitamin D 24-hydroxylase (CYP24A1) was induced. Together with the observed rapid decrease in SOST/sclerostin levels in response to PTH, endocrine regulation of sclerostin production appears to be an important determinant of sclerostin levels. These findings confirm that the human SOST gene and sclerostin expression can be considered to be directly 1,25D-responsive in osteocytes.
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Affiliation(s)
- Asiri R Wijenayaka
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, SA, Australia.
| | - Matthew Prideaux
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, SA, Australia
| | - Dongqing Yang
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, SA, Australia
| | - Howard A Morris
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - David M Findlay
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, SA, Australia
| | - Paul H Anderson
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Gerald J Atkins
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, SA, Australia
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82
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Bach-Gansmo FL, Brüel A, Jensen MV, Ebbesen EN, Birkedal H, Thomsen JS. Osteocyte lacunar properties and cortical microstructure in human iliac crest as a function of age and sex. Bone 2016; 91:11-9. [PMID: 27397700 DOI: 10.1016/j.bone.2016.07.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 06/27/2016] [Accepted: 07/06/2016] [Indexed: 12/24/2022]
Abstract
Osteocytes are suggested to play a central role in bone remodeling. Evaluation of iliac crest biopsies is a standard procedure for evaluating bone conditions in the clinical setting. Despite the widespread use of such biopsies, little is known about the population of osteocytes in the iliac crest from normal individuals. Contradicting results have been reported on osteocyte lacunar properties in human bone. Hence, a solid understanding of the osteocyte population in healthy bone and the effect of age and sex is needed as good reference data are lacking. Furthermore, the role of cortical bone in bone quality has recently been suggested to be more important than previously realized. Therefore, the present study assesses osteocyte lacunar properties and cortical microstructure of the iliac crest as a function of age and sex. A total of 88 iliac crest bone samples from healthy individuals (46 women, aged 18.5-96.4years and 42 men, aged 22.6-94.6years) with an even age-distribution were examined using synchrotron radiation μCT and in house μCT, with >5×10(6) osteocyte lacunae measured and analyzed. The study revealed that osteocyte lacunar volumes were unaffected by both age and sex. Osteocyte lacunar density did not differ between women and men, and only showed a significant decrease with age when pooling data from both sexes. Cortical porosity and Haversian canal density increased while cortical thickness decreased with age, with cortical thinning dominating the age-related cortical bone loss. None of the cortical microstructural parameters showed any sex dependency. Only weak links between osteocyte lacunar properties and cortical microstructural properties in iliac crest bone were found. Interestingly, the Haversian canal diameters were significantly but weakly negatively correlated with osteocyte lacunar volumes.
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Affiliation(s)
| | - Annemarie Brüel
- Department of Biomedicine, Aarhus University, Aarhus, Denmark.
| | | | | | - Henrik Birkedal
- Department of Chemistry and iNANO, Aarhus University, Aarhus, Denmark.
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83
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Mabilleau G, Perrot R, Flatt PR, Irwin N, Chappard D. High fat-fed diabetic mice present with profound alterations of the osteocyte network. Bone 2016; 90:99-106. [PMID: 27312542 DOI: 10.1016/j.bone.2016.06.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 05/28/2016] [Accepted: 06/11/2016] [Indexed: 12/31/2022]
Abstract
Diabetes mellitus is considered to be an independent risk factor for bone fragility fractures. Reductions in bone mass, observed only with type 1 diabetes mellitus, as well as modifications of bone microarchitectures and tissue material properties are landmarks of diabetes-related bone alterations. An interesting feature observed in type 2 diabetes mellitus (T2DM) is the augmented concentration in circulating sclerostin. This observation prompts us to hypothesize that modifications of osteocyte network and perilacunar mineralization occur in T2DM. As such, the aims of the present study were to ascertain by quantitative backscattered electron imaging, confocal microscopy and image analysis, modifications of perilacunar tissue mineral density, osteocyte morphology and osteocyte network topology in a mouse model of high fat-induced type 2 diabetes. As compared with lean control animals, diabetic mice exhibited a significant 48% decrease in perilacunar mineralization heterogeneity although mean perilacunar mineralization was unchanged. Furthermore, in diabetic animals, osteocyte volume was significantly augmented by 34% with no change in the overall number of dendrite processes. Finally, the network topology was profoundly modified in diabetic mice with increases in the mean node degree, mean node volume and hub numbers whilst the mean link length was reduced. Overall, it appeared that in diabetic animals, the dendritic network exhibited features of a scale-free network as opposed to the single-scale characteristic observed in lean controls. However, it is important to ascertain whether diabetic patients exhibit such modifications of the osteocyte network and whether anti-diabetic drugs could restore normal osteocyte and network parameters, thereby improving bone quality and protecting against fragility fractures.
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Affiliation(s)
- Guillaume Mabilleau
- GEROM-LHEA, Institut de Biologie en Santé, Angers, Université d'Angers, CHU d'Angers, 49933 Angers, France; SCIAM, Institut de Biologie en Santé, Université d'Angers, CHU d'Angers, 49933 Angers, France.
| | - Rodolphe Perrot
- SCIAM, Institut de Biologie en Santé, Université d'Angers, CHU d'Angers, 49933 Angers, France
| | - Peter R Flatt
- SAAD Centre for Pharmacy and Diabetes, Diabetes Research group, Biomedical Sciences Research Institute, University of Ulster, BT52 1SA, Coleraine, United Kingdom
| | - Nigel Irwin
- SAAD Centre for Pharmacy and Diabetes, Diabetes Research group, Biomedical Sciences Research Institute, University of Ulster, BT52 1SA, Coleraine, United Kingdom
| | - Daniel Chappard
- GEROM-LHEA, Institut de Biologie en Santé, Angers, Université d'Angers, CHU d'Angers, 49933 Angers, France; SCIAM, Institut de Biologie en Santé, Université d'Angers, CHU d'Angers, 49933 Angers, France
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84
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Jáuregui EJ, Akil O, Acevedo C, Hall-Glenn F, Tsai BS, Bale HA, Liebenberg E, Humphrey MB, Ritchie RO, Lustig LR, Alliston T. Parallel mechanisms suppress cochlear bone remodeling to protect hearing. Bone 2016; 89:7-15. [PMID: 27085457 PMCID: PMC4916019 DOI: 10.1016/j.bone.2016.04.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 04/02/2016] [Accepted: 04/10/2016] [Indexed: 01/08/2023]
Abstract
Bone remodeling, a combination of bone resorption and formation, requires precise regulation of cellular and molecular signaling to maintain proper bone quality. Whereas osteoblasts deposit and osteoclasts resorb bone matrix, osteocytes both dynamically resorb and replace perilacunar bone matrix. Osteocytes secrete proteases like matrix metalloproteinase-13 (MMP13) to maintain the material quality of bone matrix through perilacunar remodeling (PLR). Deregulated bone remodeling impairs bone quality and can compromise hearing since the auditory transduction mechanism is within bone. Understanding the mechanisms regulating cochlear bone provides unique ways to assess bone quality independent of other aspects that contribute to bone mechanical behavior. Cochlear bone is singular in its regulation of remodeling by expressing high levels of osteoprotegerin. Since cochlear bone expresses a key PLR enzyme, MMP13, we examined whether cochlear bone relies on, or is protected from, osteocyte-mediated PLR to maintain hearing and bone quality using a mouse model lacking MMP13 (MMP13(-/-)). We investigated the canalicular network, collagen organization, lacunar volume via micro-computed tomography, and dynamic histomorphometry. Despite finding defects in these hallmarks of PLR in MMP13(-/-) long bones, cochlear bone revealed no differences in these markers, nor hearing loss as measured by auditory brainstem response (ABR) or distortion product oto-acoustic emissions (DPOAEs), between wild type and MMP13(-/-) mice. Dynamic histomorphometry revealed abundant PLR by tibial osteocytes, but near absence in cochlear bone. Cochlear suppression of PLR corresponds to repression of several key PLR genes in the cochlea relative to long bones. These data suggest that cochlear bone uniquely maintains bone quality and hearing independent of MMP13-mediated osteocytic PLR. Furthermore, the cochlea employs parallel mechanisms to inhibit remodeling by osteoclasts and osteoblasts, and by osteocytes, to protect hearing. Understanding the cellular and molecular mechanisms that confer site-specific control of bone remodeling has the potential to elucidate new pathways that are deregulated in skeletal disease.
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Affiliation(s)
- Emmanuel J Jáuregui
- Department of Orthopaedic Surgery, University of California, San Francisco, United States
| | - Omar Akil
- Department of Otolaryngology-Head & Neck Surgery, University of California, San Francisco, United States
| | - Claire Acevedo
- Department of Orthopaedic Surgery, University of California, San Francisco, United States; Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Faith Hall-Glenn
- Department of Orthopaedic Surgery, University of California, San Francisco, United States
| | - Betty S Tsai
- Department of Otorhinolaryngology, University of Oklahoma Health Sciences Center, United States
| | - Hrishikesh A Bale
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Ellen Liebenberg
- Department of Orthopaedic Surgery, University of California, San Francisco, United States
| | - Mary Beth Humphrey
- Department of Medicine, University of Oklahoma Health Sciences Center, United States
| | - Robert O Ritchie
- Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Lawrence R Lustig
- Department of Otolaryngology-Head & Neck Surgery, University of California, San Francisco, United States
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco, United States; Department of Otolaryngology-Head & Neck Surgery, University of California, San Francisco, United States.
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85
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Prideaux M, Schutz C, Wijenayaka AR, Findlay DM, Campbell DG, Solomon LB, Atkins GJ. Isolation of osteocytes from human trabecular bone. Bone 2016; 88:64-72. [PMID: 27109824 DOI: 10.1016/j.bone.2016.04.017] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 03/29/2016] [Accepted: 04/17/2016] [Indexed: 12/22/2022]
Abstract
Osteocytes are essential regulators of bone homeostasis. However, they are difficult to study due to their location within the bone mineralised matrix. Although several techniques have been published for the isolation of osteocytes from mouse bone, no such technique has been described for human osteocytes. We have therefore developed a protocol for the isolation of osteocytes from human trabecular bone samples acquired during surgery. The cells were digested from the bone matrix by sequential collagenase and ethylenediaminetetraacetic acid (EDTA) digestions and the cells from later digests displayed characteristic dendritic osteocyte morphology when cultured ex vivo. Furthermore, the cells expressed characteristic osteocyte marker genes, such as E11, dentin matrix protein 1 (DMP1), SOST, matrix extracellular phosphoglycoprotein (MEPE) and phosphate regulating endopeptidase homologue, X-linked (PHEX). In addition, genes associated with osteocyte perilacunar remodelling, including matrix metallopeptidase-13 (MMP13), cathepsin K (CTSK) and carbonic anhydrase 2 (CAR2) were expressed. The cells also responded to parathyroid hormone (PTH) by downregulating SOST mRNA expression and to 1α,25-dihydroxyvitamin D3 (1,25D) by upregulating fibroblast growth factor 23 (FGF23) mRNA expression. Therefore, the cells behave in a similar manner to osteocytes in vivo. These cells represent an important tool in enhancing current knowledge in human osteocyte biology.
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Affiliation(s)
- Matthew Prideaux
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA 5005, Australia.
| | - Christine Schutz
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA 5005, Australia; Wakefield Orthopaedic Clinic, Adelaide, SA 5000, Australia
| | - Asiri R Wijenayaka
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA 5005, Australia
| | - David M Findlay
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA 5005, Australia
| | | | - Lucian B Solomon
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA 5005, Australia
| | - Gerald J Atkins
- Centre for Orthopaedic and Trauma Research, Discipline of Orthopaedics and Trauma, University of Adelaide, Adelaide, SA 5005, Australia.
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86
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Schiavone S, Morgese MG, Mhillaj E, Bove M, De Giorgi A, Cantatore FP, Camerino C, Tucci P, Maffulli N, Cuomo V, Trabace L. Chronic Psychosocial Stress Impairs Bone Homeostasis: A Study in the Social Isolation Reared Rat. Front Pharmacol 2016; 7:152. [PMID: 27375486 PMCID: PMC4896906 DOI: 10.3389/fphar.2016.00152] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 05/26/2016] [Indexed: 12/31/2022] Open
Abstract
Chronic psychosocial stress is a key player in the onset and aggravation of mental diseases, including psychosis. Although a strong association between this psychiatric condition and other medical co-morbidities has been recently demonstrated, few data on the link between psychosis and bone homeostasis are actually available. The aim of this study was to investigate whether chronic psychosocial stress induced by 4 or 7 weeks of social isolation in drug-naïve male Wistar rats could alter bone homeostasis in terms of bone thickness, mineral density and content, as well as markers of bone formation and resorption (sclerostin, cathepsin K, and CTX-I). We found that bone mineral density was increased in rats exposed to 7 weeks of social isolation, while no differences were detected in bone mineral content and area. Moreover, 7 weeks of social isolation lead to increase of femur thickness with respect to controls, suggesting the development of a hyperostosis condition. Isolated rats showed no changes in sclerostin levels, a marker of bone formation, compared to grouped animals. Conversely, bone resorption markers were significantly altered after 7 weeks of social isolation in terms of decrease in cathepsin K and increase of CTX-I. No alterations were found after 4 weeks of isolation rearing. Our observations suggest that chronic psychosocial stress might affect bone homeostasis, more likely independently from drug treatment. Thus, the social isolation model might help to identify possible new therapeutic targets to treat the burden of chronic psychosocial stress and to attempt alternative therapy choices.
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Affiliation(s)
- Stefania Schiavone
- Department of Experimental and Clinical Medicine, University of Foggia Foggia, Italy
| | - Maria G Morgese
- Department of Experimental and Clinical Medicine, University of Foggia Foggia, Italy
| | - Emanuela Mhillaj
- Department of Physiology and Pharmacology, "Sapienza" University of Rome Rome, Italy
| | - Maria Bove
- Department of Physiology and Pharmacology, "Sapienza" University of Rome Rome, Italy
| | - Angelo De Giorgi
- Dual Diagnosis Unit, Azienda Sanitaria Locale della Provincia di Foggia Foggia, Italy
| | | | - Claudia Camerino
- Department of Physiology and Pharmacology, "Sapienza" University of RomeRome, Italy; Department of Basic Medical Science, Neuroscience and Sense Organs, University of BariBari, Italy
| | - Paolo Tucci
- Department of Experimental and Clinical Medicine, University of Foggia Foggia, Italy
| | - Nicola Maffulli
- Department of Musculoskeletal Disorders, School of Medicine and Surgery, University of SalernoSalerno, Italy; Centre for Sports and Exercise Medicine, Barts and The London School of Medicine and DentistryLondon, UK
| | - Vincenzo Cuomo
- Department of Physiology and Pharmacology, "Sapienza" University of Rome Rome, Italy
| | - Luigia Trabace
- Department of Experimental and Clinical Medicine, University of Foggia Foggia, Italy
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87
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Prideaux M, Findlay DM, Atkins GJ. Osteocytes: The master cells in bone remodelling. Curr Opin Pharmacol 2016; 28:24-30. [DOI: 10.1016/j.coph.2016.02.003] [Citation(s) in RCA: 127] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 01/14/2016] [Accepted: 02/09/2016] [Indexed: 10/22/2022]
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88
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Hay E, Bouaziz W, Funck-Brentano T, Cohen-Solal M. Sclerostin and Bone Aging: A Mini-Review. Gerontology 2016; 62:618-623. [DOI: 10.1159/000446278] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 04/19/2016] [Indexed: 11/19/2022] Open
Abstract
Sclerostin, mainly produced by osteocytes, is now considered a major regulator of bone formation. Identified from patients with a low bone mass, sclerostin inhibits the Wnt pathway by binding to LRP5/6 and subsequently increases bone formation. Sclerostin may also play a role in the mediation of systemic and local factors such as calcitriol, PTH, glucocorticoids and tumor necrosis factor-alpha. Circulating sclerostin levels increase with age and with the decline of kidney function. However, they are surprisingly higher in patients with a high bone mineral density, suggesting that sclerostin may be a relevant marker of the pool of mature osteocytes. The anti-anabolic properties lead to the development of anti-sclerostin biotherapies that are under current evaluation. The results of these clinical trials will open new promising opportunities for the treatment of osteoporosis and bone fragility fractures.
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89
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Liu ES, Martins JS, Raimann A, Chae BT, Brooks DJ, Jorgetti V, Bouxsein ML, Demay MB. 1,25-Dihydroxyvitamin D Alone Improves Skeletal Growth, Microarchitecture, and Strength in a Murine Model of XLH, Despite Enhanced FGF23 Expression. J Bone Miner Res 2016; 31:929-39. [PMID: 26751835 PMCID: PMC4862933 DOI: 10.1002/jbmr.2783] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 01/05/2016] [Accepted: 01/07/2016] [Indexed: 01/24/2023]
Abstract
X-linked hypophosphatemia (XLH) is characterized by impaired renal tubular reabsorption of phosphate owing to increased circulating FGF23 levels, resulting in rickets in growing children and impaired bone mineralization. Increased FGF23 decreases renal brush border membrane sodium-dependent phosphate transporter IIa (Npt2a) causing renal phosphate wasting, impairs 1-α hydroxylation of 25-hydroxyvitamin D, and induces the vitamin D 24-hydroxylase, leading to inappropriately low circulating levels of 1,25-dihydroxyvitamin D (1,25D). The goal of therapy is prevention of rickets and improvement of growth in children by phosphate and 1,25D supplementation. However, this therapy is often complicated by hypercalcemia and nephrocalcinosis and does not always prevent hyperparathyroidism. To determine if 1,25D or blocking FGF23 action can improve the skeletal phenotype without phosphate supplementation, mice with XLH (Hyp) were treated with daily 1,25D repletion, FGF23 antibodies (FGF23Ab), or biweekly high-dose 1,25D from d2 to d75 without supplemental phosphate. All treatments maintained normocalcemia, increased serum phosphate, and normalized parathyroid hormone levels. They also prevented the loss of Npt2a, α-Klotho, and pERK1/2 immunoreactivity observed in the kidneys of untreated Hyp mice. Daily treatment with 1,25D decreased urine phosphate losses despite a marked increase in bone FGF23 mRNA and in circulating FGF23 levels. Daily 1,25D was more effective than other treatments in normalizing the growth plate and metaphyseal organization. In addition to being the only therapy that normalized lumbar vertebral height and body weight, daily 1,25D therapy normalized bone geometry and was more effective than FGF23Ab in improving trabecular bone structure. Daily 1,25D and FGF23Ab improved cortical microarchitecture and whole-bone biomechanical properties more so than biweekly 1,25D. Thus, monotherapy with 1,25D improves growth, skeletal microarchitecture, and bone strength in the absence of phosphate supplementation despite enhancing FGF23 expression, demonstrating that 1,25D has direct beneficial effects on the skeleton in XLH, independent of its role in phosphate homeostasis. © 2016 American Society for Bone and Mineral Research.
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Affiliation(s)
- Eva S Liu
- Division of Endocrinology, Diabetes, and Hypertension, Brigham and Women's Hospital, Boston, MA, USA.,Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
| | - Janaina S Martins
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA.,Division of Nephrology, Universidade de São Paulo, São Paulo, Brazil
| | - Adalbert Raimann
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA.,Department of Pediatrics and Adolescent Medicine, Medical University Vienna, Vienna, Austria
| | | | - Daniel J Brooks
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Department of Orthopedics, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Vanda Jorgetti
- Division of Nephrology, Universidade de São Paulo, São Paulo, Brazil
| | - Mary L Bouxsein
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA.,Department of Orthopedics, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Marie B Demay
- Endocrine Unit, Massachusetts General Hospital, Boston, MA, USA.,Harvard Medical School, Boston, MA, USA
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90
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Ormsby RT, Cantley M, Kogawa M, Solomon LB, Haynes DR, Findlay DM, Atkins GJ. Evidence that osteocyte perilacunar remodelling contributes to polyethylene wear particle induced osteolysis. Acta Biomater 2016; 33:242-51. [PMID: 26796208 DOI: 10.1016/j.actbio.2016.01.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 01/12/2016] [Accepted: 01/16/2016] [Indexed: 01/04/2023]
Abstract
Periprosthetic osteolysis (PO) leading to aseptic loosening, is the most common cause of failure of total hip replacement (THR) in the mid- to long-term. Polyethylene (PE) particulates from the wear of prosthesis liners are bioactive and are implicated in the initiation and or progression of osteolysis. Evidence exists that cells of the osteoblast/osteocyte lineage are affected by PE particles and contribute to the catabolic response by promoting osteoclastic bone resorption. In this study, we hypothesised that osteocytes contribute directly to PO by removing bone from their perilacunar matrix. Osteocyte responses to ultra-high molecular weight PE (UHMWPE) particles were examined in vitro in human primary osteocyte-like cultures, in vivo in the mouse calvarial osteolysis model, and in the acetabulum of patients undergoing revision total hip replacement (THR) surgery for PO. Osteocytes exposed to UHMWPE particles showed upregulated expression of catabolic markers, MMP-13, carbonic anhydrase 2 (CA2), cathepsin K (CTSK) and tartrate resistant acid phosphatase (TRAP), with no effect on cell viability, as assessed by Caspase 3 activity. Consistent with this catabolic activity causing perilacunar bone loss, histological analysis of calvarial sections from mice exposed to UHMWPE revealed a significant (p<0.001) increase in osteocyte lacunar area (Lac.Ar) compared to sham-operated animals. Furthermore, acetabular biopsies from patients with PO also showed significantly (p<0.001) increased osteocyte lacunar size in trabecular bone adjacent to PE particles, compared with osteocyte lacunar size in bone from primary THR patients. Together, these findings suggest a previously unrecognised action of UHMWPE wear particles on osteocytes, which directly results in a loss of osteocyte perilacunar bone. This action may exacerbate the indirect pro-osteoclastic action of UHMWPE-affected osteocytes, previously shown to contribute to aseptic loosening of orthopaedic implants. STATEMENT OF SIGNIFICANCE This study addresses the clinical problem of periprosthetic osteolysis, bone loss in response to polyethylene wear particles derived from materials used in orthopaedic implants. Periprosthetic osteolysis has been thought to be due largely to wear particles stimulating the activity of bone resorbing osteoclasts. However, in this study we demonstrate for the first time that polyethylene particles stimulate another type of bone loss, mediated by the direct activity of bone mineral embedded osteocytes, termed osteocytic osteolysis or osteocyte perilacunar remodelling. This study provides new mechanistic insight into wear-particle mediated bone loss and represents a new paradigm for the way in which bone cells, namely osteocytes, the key controlling cell type in bone, react to biomaterials.
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91
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Gardinier JD, Al-Omaishi S, Morris MD, Kohn DH. PTH signaling mediates perilacunar remodeling during exercise. Matrix Biol 2016; 52-54:162-175. [PMID: 26924474 DOI: 10.1016/j.matbio.2016.02.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/16/2016] [Accepted: 02/22/2016] [Indexed: 11/30/2022]
Abstract
Mechanical loading and release of endogenous parathyroid hormone (PTH) during exercise facilitate the adaptation of bone. However, it remains unclear how exercise and PTH influence the composition of bone and how exercise and PTH-mediated compositional changes influence the mechanical properties of bone. Thus, the primary purpose of this study was to establish compositional changes within osteocytes' perilacunar region of cortical bone following exercise, and evaluate the influence of endogenous PTH signaling on this perilacunar adaptation. Raman spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) were used to evaluate tissue composition surrounding individual lacuna within the tibia of 19week old male mice exposed to treadmill running for 3weeks. As a result of exercise, tissue within the perilacunar region (within 0-5μm of the lacuna wall) had a lower mineral-to-matrix ratio (MMR) compared to sedentary controls. In addition, exercise also increased the carbonate-to-phosphate ratio (CPR) across both perilacunar and non-perilacunar regions (5-10μm and 10-15μm from the lacuna walls). Tibial post-yield work had a significant negative correlation with perilacunar MMR. Inhibition of PTH activity with PTH(7-34) demonstrated that perilacunar remodeling during exercise was dependent on the cellular response to endogenous PTH. The osteocytes' response to endogenous PTH during exercise was characterized by a significant reduction in SOST expression and significant increase in FGF-23 expression. The potential reduction in phosphate levels due to FGF-23 expression may explain the increase in carbonate substitution. Overall, this is the first study to demonstrate that adaptation in tissue composition is localized around individual osteocytes, may contribute to the changes in whole bone mechanics during exercise, and that PTH signaling during exercise contributes to these adaptations.
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Affiliation(s)
- Joseph D Gardinier
- Bone and Joint Center, Henry Ford Hospital, Detroit, MI 48202, USA; Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI 48109, USA
| | - Salam Al-Omaishi
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Michael D Morris
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - David H Kohn
- Department of Biologic and Materials Sciences, University of Michigan, Ann Arbor, MI 48109, USA; Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA.
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92
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Ross RD, Mashiatulla M, Robling AG, Miller LM, Sumner DR. Bone Matrix Composition Following PTH Treatment is Not Dependent on Sclerostin Status. Calcif Tissue Int 2016; 98:149-57. [PMID: 26514840 PMCID: PMC7391132 DOI: 10.1007/s00223-015-0074-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 10/09/2015] [Indexed: 12/28/2022]
Abstract
Sclerostin and parathyroid hormones are strong negative and positive regulators of bone formation, respectively. The anabolic response induced by intermittent (iPTH) treatment is sclerostin status-dependent. However, the interaction between sclerostin and iPTH at the matrix level is unknown. The goal of the current study was to determine if iPTH treatment affects matrix composition and, if so, whether these effects are dependent on sclerostin status. Humeral trabecular and cortical bone sites from 16 week old male wild-type (WT) and sclerostin knockout (KO) mice, which had been treated with vehicle or iPTH from age 10-16 weeks, were examined by micro-computed tomography (µCT) to measure bone volume, backscatter scanning electron microscopy (bSEM) to assess global mineralization, and Fourier transform infrared microspectroscopy (FTIRM) to examine matrix composition (mineral-to-matrix ratio, crystallinity, collagen cross-link ratio, and carbonate substitution). The FTIRM measurements were restricted to the tissue formed during the 6-week treatment period. iPTH treatment led to increased trabecular bone volume (p < 0.001) and this effect was much greater in KO mice than WT mice (interaction effect, p < 0.001). iPTH treatment led to reduced trabecular crystallinity (p = 0.047), increased cortical bone area (p < 0.001), decreased cortical bone crystallinity (p = 0.002) and increased cortical bone collagen cross-linking (p = 0.028) to similar degrees in both WT and KO mice. Compared to WT mice, sclerostin KO mice had higher trabecular and cortical bone mass (p < 0.001) and lower mineral-to-matrix ratio in the trabecular (p = 0.010) and cortical (p = 0.016) compartments. Thus, iPTH-induced changes in bone mass are dependent upon sclerostin status in the trabecular compartment, but not in the cortical compartment. In contrast, iPTH-induced changes in matrix composition are sclerostin-independent in both trabecular and cortical compartments.
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Affiliation(s)
- Ryan D Ross
- Department of Anatomy and Cell Biology, Rush University Medical Center, 600 South Paulina, Suite 507, Chicago, IL, 60612, USA.
| | - Maleeha Mashiatulla
- Department of Anatomy and Cell Biology, Rush University Medical Center, 600 South Paulina, Suite 507, Chicago, IL, 60612, USA
- Department of Bioengineering, University of Illinois Chicago, Chicago, IL, USA
| | - Alexander G Robling
- Department of Anatomy and Cell Biology, Indiana University, Indianapolis, IN, USA
- Richard L. Roudebush VA Medical Center, Indianapolis, IN, USA
| | - Lisa M Miller
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA
- National Synchrotron Light Source-II, Brookhaven National Laboratory, Upton, NY, USA
| | - D Rick Sumner
- Department of Anatomy and Cell Biology, Rush University Medical Center, 600 South Paulina, Suite 507, Chicago, IL, 60612, USA.
- Department of Bioengineering, University of Illinois Chicago, Chicago, IL, USA.
- Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, IL, USA.
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93
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Wijenayaka AR, Yang D, Prideaux M, Ito N, Kogawa M, Anderson PH, Morris HA, Solomon LB, Loots GG, Findlay DM, Atkins GJ. 1α,25-dihydroxyvitamin D3 stimulates human SOST gene expression and sclerostin secretion. Mol Cell Endocrinol 2015; 413:157-67. [PMID: 26112182 DOI: 10.1016/j.mce.2015.06.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 06/17/2015] [Accepted: 06/18/2015] [Indexed: 01/04/2023]
Abstract
Sclerostin, the SOST gene product, is a negative regulator of bone formation and a positive regulator of bone resorption. In this study, treatment of human primary osteoblasts, including cells differentiated to an osteocyte-like stage, with 1α,25-dihydroxyvitaminD3 (1,25D) resulted in the dose-dependent increased expression of SOST mRNA. A similar effect was observed in human trabecular bone samples cultured ex vivo, and in osteocyte-like cultures of differentiated SAOS2 cells. Treatment of SAOS2 cells with 1,25D resulted in the production and secretion of sclerostin protein. In silico analysis of the human SOST gene revealed a single putative DR3-type vitamin D response element (VDRE) at position -6216 bp upstream of the transcription start site (TSS). This sequence was confirmed to have strong VDRE activity by luciferase reporter assays and electrophoretic mobility shift analysis (EMSA). Sequence substitution in the VDR/RXR half-sites abolished VDRE reporter activity and binding of nuclear proteins. A 6.3 kb fragment of the human proximal SOST promoter demonstrated responsiveness to 1,25D. The addition of the evolutionary conserved region 5 (ECR5), a known bone specific enhancer region, ahead of the 6.3 kb fragment increased basal promoter activity but did not increase 1,25D responsiveness. Site-specific mutagenesis abolished the responsiveness of the 6.3 kb promoter to 1,25D. We conclude that 1,25D is a direct regulator of human SOST gene and sclerostin protein expression, extending the pathways of control of sclerostin expression. At least some of this responsiveness is mediated by the identified classical VDRE however the nature of the transcriptional regulation by 1,25D warrants further investigation.
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Affiliation(s)
- Asiri R Wijenayaka
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Dongqing Yang
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Matthew Prideaux
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Nobuaki Ito
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Masakazu Kogawa
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Paul H Anderson
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5001, Australia
| | - Howard A Morris
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia 5001, Australia
| | - Lucian B Solomon
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Gabriela G Loots
- Lawrence Livermore National Laboratories, Physical and Life Sciences Directorate, Livermore, CA, USA; University of California at Merced, School of Natural Sciences, Merced, CA, USA
| | - David M Findlay
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Gerald J Atkins
- Centre for Orthopaedic and Trauma Research, University of Adelaide, Adelaide, South Australia 5005, Australia.
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Clarke MV, Russell PK, Findlay DM, Sastra S, Anderson PH, Skinner JP, Atkins GJ, Zajac JD, Davey RA. A Role for the Calcitonin Receptor to Limit Bone Loss During Lactation in Female Mice by Inhibiting Osteocytic Osteolysis. Endocrinology 2015; 156:3203-14. [PMID: 26135836 DOI: 10.1210/en.2015-1345] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
During lactation, the large transfer of calcium from the mother to the milk is primarily sourced from the maternal skeleton. To determine whether the calcitonin receptor (CTR) plays a physiological role to protect the skeleton from excessive resorption during lactation, we assessed the maternal skeleton of global CTR knockout (CTRKO) and littermate control mice at the end of lactation (postnatal day 21). Micro-computed tomography analyses showed no effect on trabecular or cortical bone in the distal femur and L1 vertebra of maternal global CTR deletion at the end of lactation in global CTRKO mice compared with that in control mice. Bone resorption, as assessed by osteoclast number and activity at the end of lactation, was unaffected by maternal CTR deletion. Cathepsin K, carbonic anhydrase 2, matrix metalloproteinase 13, and receptor activator of nuclear factor-κB ligand mRNA levels, however, were markedly elevated by 3- to 6.5-fold in whole bone of lactating global CTRKO females. Because these genes have been shown to be up-regulated in osteocytes during lactation when osteocytes resorb their surrounding bone matrix, together with their reported expression of the CTR, we determined the osteocyte lacunar area in cortical bone. After lactation, the top 20% of osteocyte lacunar area in global CTRKO mice was 10% larger than the top 20% in control mice. These data are consistent with an increased osteocytic osteolysis in global CTRKO mice during lactation, which is further supported by the increased serum calcium observed in global CTRKO mice after lactation. These results provide evidence for a physiological role for the CTR to protect the maternal skeleton during lactation by a direct action on osteocytes to inhibit osteolysis.
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Affiliation(s)
- Michele V Clarke
- Department of Medicine (M.V.C., P.K.R., S.S., J.P.S., J.D.Z., R.A.D.), Austin Health, University of Melbourne, Heidelberg, 3084 Victoria, Australia; Centre for Orthopaedic and Trauma Research (D.M.F., G.J.A.), University of Adelaide, 5005 Adelaide, Australia; and School of Pharmacy and Medical Sciences (P.H.A.), University of South Australia, 5005 Adelaide, Australia
| | - Patricia K Russell
- Department of Medicine (M.V.C., P.K.R., S.S., J.P.S., J.D.Z., R.A.D.), Austin Health, University of Melbourne, Heidelberg, 3084 Victoria, Australia; Centre for Orthopaedic and Trauma Research (D.M.F., G.J.A.), University of Adelaide, 5005 Adelaide, Australia; and School of Pharmacy and Medical Sciences (P.H.A.), University of South Australia, 5005 Adelaide, Australia
| | - David M Findlay
- Department of Medicine (M.V.C., P.K.R., S.S., J.P.S., J.D.Z., R.A.D.), Austin Health, University of Melbourne, Heidelberg, 3084 Victoria, Australia; Centre for Orthopaedic and Trauma Research (D.M.F., G.J.A.), University of Adelaide, 5005 Adelaide, Australia; and School of Pharmacy and Medical Sciences (P.H.A.), University of South Australia, 5005 Adelaide, Australia
| | - Stephen Sastra
- Department of Medicine (M.V.C., P.K.R., S.S., J.P.S., J.D.Z., R.A.D.), Austin Health, University of Melbourne, Heidelberg, 3084 Victoria, Australia; Centre for Orthopaedic and Trauma Research (D.M.F., G.J.A.), University of Adelaide, 5005 Adelaide, Australia; and School of Pharmacy and Medical Sciences (P.H.A.), University of South Australia, 5005 Adelaide, Australia
| | - Paul H Anderson
- Department of Medicine (M.V.C., P.K.R., S.S., J.P.S., J.D.Z., R.A.D.), Austin Health, University of Melbourne, Heidelberg, 3084 Victoria, Australia; Centre for Orthopaedic and Trauma Research (D.M.F., G.J.A.), University of Adelaide, 5005 Adelaide, Australia; and School of Pharmacy and Medical Sciences (P.H.A.), University of South Australia, 5005 Adelaide, Australia
| | - Jarrod P Skinner
- Department of Medicine (M.V.C., P.K.R., S.S., J.P.S., J.D.Z., R.A.D.), Austin Health, University of Melbourne, Heidelberg, 3084 Victoria, Australia; Centre for Orthopaedic and Trauma Research (D.M.F., G.J.A.), University of Adelaide, 5005 Adelaide, Australia; and School of Pharmacy and Medical Sciences (P.H.A.), University of South Australia, 5005 Adelaide, Australia
| | - Gerald J Atkins
- Department of Medicine (M.V.C., P.K.R., S.S., J.P.S., J.D.Z., R.A.D.), Austin Health, University of Melbourne, Heidelberg, 3084 Victoria, Australia; Centre for Orthopaedic and Trauma Research (D.M.F., G.J.A.), University of Adelaide, 5005 Adelaide, Australia; and School of Pharmacy and Medical Sciences (P.H.A.), University of South Australia, 5005 Adelaide, Australia
| | - Jeffrey D Zajac
- Department of Medicine (M.V.C., P.K.R., S.S., J.P.S., J.D.Z., R.A.D.), Austin Health, University of Melbourne, Heidelberg, 3084 Victoria, Australia; Centre for Orthopaedic and Trauma Research (D.M.F., G.J.A.), University of Adelaide, 5005 Adelaide, Australia; and School of Pharmacy and Medical Sciences (P.H.A.), University of South Australia, 5005 Adelaide, Australia
| | - Rachel A Davey
- Department of Medicine (M.V.C., P.K.R., S.S., J.P.S., J.D.Z., R.A.D.), Austin Health, University of Melbourne, Heidelberg, 3084 Victoria, Australia; Centre for Orthopaedic and Trauma Research (D.M.F., G.J.A.), University of Adelaide, 5005 Adelaide, Australia; and School of Pharmacy and Medical Sciences (P.H.A.), University of South Australia, 5005 Adelaide, Australia
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95
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Pelletier S, Confavreux CB, Haesebaert J, Guebre-Egziabher F, Bacchetta J, Carlier MC, Chardon L, Laville M, Chapurlat R, London GM, Lafage-Proust MH, Fouque D. Serum sclerostin: the missing link in the bone-vessel cross-talk in hemodialysis patients? Osteoporos Int 2015; 26:2165-74. [PMID: 25910747 DOI: 10.1007/s00198-015-3127-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Accepted: 04/01/2015] [Indexed: 10/23/2022]
Abstract
UNLABELLED We found for the first time that in maintenance hemodialysis patients, higher sclerostin serum level was associated with severe abdominal aortic calcification (AAC). In addition, cortical bone microarchitecture (density and thickness) assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT) at tibia was also independently associated with severe AAC. These results suggest that sclerostin may be involved in the association of mineral and bone disorder with vascular calcification in hemodialysis patients. INTRODUCTION Severe abdominal aortic calcifications are predictive of high cardiovascular mortality in maintenance hemodialysis (MHD) patients. In patients with end-stage renal disease, a high aortic calcification score was associated with lower bone turnover on bone biopsies. Thus, we hypothesized that sclerostin, a Wnt pathway inhibitor mainly secreted by osteocytes and acting on osteoblasts to reduce bone formation, may be associated with vascular calcifications in MHD patients. METHODS Fifty-three MHD patients, aged 53 years [35-63] (median [Q1-Q3]) were included. Serum was sampled before the MHD session to assay sclerostin. Framingham score was computed and the abdominal aortic calcification (AAC) score was assessed according to Kauppila method on lateral spine imaging using DEXA. Tibia bone status was evaluated by high-resolution peripheral quantitative computed tomography (HR-pQCT). Patients were distributed into two groups according to their AAC score: patients with mild or without AAC (score below 6) versus patients with severe AAC (score of 6 and above). RESULTS In multivariate analysis, after adjustment on age, dialysis duration and diabetes, serum sclerostin and cortical thickness were independently associated with severe AAC (odds ratio (OR) = 1.43 for each 0.1 ng/mL increase [95 % confidence interval (CI) 1.10-1.83]; p = 0.006 and 0.16 for 1 SD increase [0.03-0.73]; p = 0.018, respectively). A second cardiovascular model adjusted on Framingham score and the above mentioned confounders showed similar results. CONCLUSIONS Elevated sclerostin serum level and poorer tibia cortical bone structure by HR-pQCT were positively and independently associated with higher odds of severe AAC in MHD patients. Serum sclerostin may become a biomarker of mineral and bone disorder and vascular risk in MHD patients.
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Affiliation(s)
- S Pelletier
- Département de Néphrologie - Bâtiment 3C, Centre Hospitalier Lyon Sud, 69495, Pierre Bénite, France,
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96
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El Khassawna T, Böcker W, Brodsky K, Weisweiler D, Govindarajan P, Kampschulte M, Thormann U, Henss A, Rohnke M, Bauer N, Müller R, Deutsch A, Ignatius A, Dürselen L, Langheinrich A, Lips KS, Schnettler R, Heiss C. Impaired extracellular matrix structure resulting from malnutrition in ovariectomized mature rats. Histochem Cell Biol 2015. [PMID: 26210855 DOI: 10.1007/s00418-015-1356-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Bone loss is a symptom related to disease and age, which reflects on bone cells and ECM. Discrepant regulation affects cell proliferation and ECM localization. Rat model of osteoporosis (OVX) was investigated against control rats (Sham) at young and old ages. Biophysical, histological and molecular techniques were implemented to examine the underlying cellular and extracellular matrix changes and to assess the mechanisms contributing to bone loss in the context of aging and the widely used osteoporotic models in rats. Bone loss exhibited a compromised function of bone cells and infiltration of adipocytes into bone marrow. However, the expression of genes regulating collagen catabolic process and adipogenesis was chronologically shifted in diseased bone in comparison with aged bone. The data showed the involvement of Wnt signaling inhibition in adipogenesis and bone loss due to over-expression of SOST in both diseased and aged bone. Further, in the OVX animals, an integrin-mediated ERK activation indicated the role of MAPK in osteoblastogenesis and adipogenesis. The increased PTH levels due to calcium and estrogen deficiency activated osteoblastogenesis. Thusly, RANKL-mediated osteoclastogenesis was initiated. Interestingly, the data show the role of MEPE regulating osteoclast-mediated resorption at late stages in osteoporotic bone. The interplay between ECM and bone cells change tissue microstructure and properties. The involvement of Wnt and MAPK pathways in activating cell proliferation has intriguing similarities to oncogenesis and myeloma. The study indicates the importance of targeting both pathways simultaneously to remedy metabolic bone diseases and age-related bone loss.
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Affiliation(s)
- Thaqif El Khassawna
- Laboratory of Experimental Trauma Surgery, Justus-Liebig University, Giessen, Germany.
| | - Wolfgang Böcker
- Laboratory of Experimental Trauma Surgery, Justus-Liebig University, Giessen, Germany. .,Department of Trauma Surgery, University Hospital of Giessen-Marburg, Rudolf-Buchheim-Strasse 7, 35385, Giessen, Germany.
| | - Katharina Brodsky
- Laboratory of Experimental Trauma Surgery, Justus-Liebig University, Giessen, Germany.
| | - David Weisweiler
- Department of Trauma Surgery, University Hospital of Giessen-Marburg, Rudolf-Buchheim-Strasse 7, 35385, Giessen, Germany.
| | | | - Marian Kampschulte
- Department of Radiology, University Hospital of Giessen-Marburg, Giessen, Germany.
| | - Ulrich Thormann
- Department of Trauma Surgery, University Hospital of Giessen-Marburg, Rudolf-Buchheim-Strasse 7, 35385, Giessen, Germany.
| | - Anja Henss
- Institute for Physical Chemistry, Justus-Liebig-University of Giessen, Giessen, Germany.
| | - Marcus Rohnke
- Institute for Physical Chemistry, Justus-Liebig-University of Giessen, Giessen, Germany.
| | - Natali Bauer
- Department of Veterinary Clinical Sciences, Clinical Pathology and Clinical Pathophysiology, Justus-Liebig University Giessen, Giessen, Germany.
| | - Robert Müller
- Center for Information Services and High Performance Computing, TU Dresden, Dresden, Germany.
| | - Andreas Deutsch
- Center for Information Services and High Performance Computing, TU Dresden, Dresden, Germany.
| | - Anita Ignatius
- Institute of Orthopedic Research and Biomechanics, Centre of Musculoskeletal Research, University of Ulm, Ulm, Germany.
| | - Lutz Dürselen
- Institute of Orthopedic Research and Biomechanics, Centre of Musculoskeletal Research, University of Ulm, Ulm, Germany.
| | - Alexander Langheinrich
- Department of Diagnostic and Interventional Radiology, BG Trauma Hospital Frankfurt/Main, Frankfurt, Germany.
| | - Katrin S Lips
- Laboratory of Experimental Trauma Surgery, Justus-Liebig University, Giessen, Germany.
| | - Reinhard Schnettler
- Laboratory of Experimental Trauma Surgery, Justus-Liebig University, Giessen, Germany. .,Department of Trauma Surgery, University Hospital of Giessen-Marburg, Rudolf-Buchheim-Strasse 7, 35385, Giessen, Germany.
| | - Christian Heiss
- Laboratory of Experimental Trauma Surgery, Justus-Liebig University, Giessen, Germany. .,Department of Trauma Surgery, University Hospital of Giessen-Marburg, Rudolf-Buchheim-Strasse 7, 35385, Giessen, Germany.
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97
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Adeva-Andany MM, Fernández-Fernández C, Sánchez-Bello R, Donapetry-García C, Martínez-Rodríguez J. The role of carbonic anhydrase in the pathogenesis of vascular calcification in humans. Atherosclerosis 2015; 241:183-91. [PMID: 26005791 DOI: 10.1016/j.atherosclerosis.2015.05.012] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Revised: 05/04/2015] [Accepted: 05/07/2015] [Indexed: 11/19/2022]
Abstract
Carbonic anhydrases are a group of isoenzymes that catalyze the reversible conversion of carbon dioxide into bicarbonate. They participate in a constellation of physiological processes in humans, including respiration, bone metabolism, and the formation of body fluids, including urine, bile, pancreatic juice, gastric secretion, saliva, aqueous humor, cerebrospinal fluid, and sweat. In addition, carbonic anhydrase may provide carbon dioxide/bicarbonate to carboxylation reactions that incorporate carbon dioxide to substrates. Several isoforms of carbonic anhydrase have been identified in humans, but their precise physiological role and the consequences of their dysfunction are mostly unknown. Carbonic anhydrase isoenzymes are involved in calcification processes in a number of biological systems, including the formation of calcareous spicules from sponges, the formation of shell in some animals, and the precipitation of calcium salts induced by several microorganisms, particularly urease-producing bacteria. In human tissues, carbonic anhydrase is implicated in calcification processes either directly by facilitating calcium carbonate deposition which in turn serves to facilitate calcium phosphate mineralization, or indirectly via its action upon γ-glutamyl-carboxylase, a carboxylase that enables the biological activation of proteins involved in calcification, such as matrix Gla protein, bone Gla protein, and Gla-rich protein. Carbonic anhydrase is implicated in calcification of human tissues, including bone and soft-tissue calcification in rheumatological disorders such as ankylosing spondylitis and dermatomyositis. Carbonic anhydrase may be also involved in bile and kidney stone formation and carcinoma-associated microcalcifications. The aim of this review is to evaluate the possible association between carbonic anhydrase isoenzymes and vascular calcification in humans.
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Affiliation(s)
- María M Adeva-Andany
- Nephrology Division, Hospital General Juan Cardona, c/ Pardo Bazán s/n, 15406 Ferrol, Spain.
| | | | - Rocío Sánchez-Bello
- Nephrology Division, Hospital General Juan Cardona, c/ Pardo Bazán s/n, 15406 Ferrol, Spain
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98
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Parathyroid Hormone Induces Bone Cell Motility and Loss of Mature Osteocyte Phenotype through L-Calcium Channel Dependent and Independent Mechanisms. PLoS One 2015; 10:e0125731. [PMID: 25942444 PMCID: PMC4420268 DOI: 10.1371/journal.pone.0125731] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/25/2015] [Indexed: 12/17/2022] Open
Abstract
Parathyroid Hormone (PTH) can exert both anabolic and catabolic effects on the skeleton, potentially through expression of the PTH type1 receptor (PTH1R), which is highly expressed in osteocytes. To determine the cellular and molecular mechanisms responsible, we examined the effects of PTH on osteoblast to osteocyte differentiation using primary osteocytes and the IDG-SW3 murine cell line, which differentiate from osteoblast to osteocyte-like cells in vitro and express GFP under control of the dentin matrix 1 (Dmp1) promoter. PTH treatment resulted in an increase in some osteoblast and early osteocyte markers and a decrease in mature osteocyte marker expression. The gene expression profile of PTH-treated Day 28 IDG-SW3 cells was similar to PTH treated primary osteocytes. PTH treatment induced striking changes in the morphology of the Dmp1-GFP positive cells in IDG-SW3 cultures and primary cells from Dmp1-GFP transgenic mice. The cells changed from a more dendritic to an elongated morphology and showed increased cell motility. E11/gp38 has been shown to be important for cell migration, however, deletion of the E11/gp38/podoplanin gene had no effect on PTH-induced motility. The effects of PTH on motility were reproduced using cAMP, but not with protein kinase A (PKA), exchange proteins activated by cAMP (Epac), protein kinase C (PKC) or phosphatidylinositol-4,5-bisphosphonate 3-kinase (Pi3K) agonists nor were they blocked by their antagonists. However, the effects of PTH were mediated through calcium signaling, specifically through L-type channels normally expressed in osteoblasts but decreased in osteocytes. PTH was shown to increase expression of this channel, but decrease the T-type channel that is normally more highly expressed in osteocytes. Inhibition of L-type calcium channel activity attenuated the effects of PTH on cell morphology and motility but did not prevent the downregulation of mature osteocyte marker expression. Taken together, these results show that PTH induces loss of the mature osteocyte phenotype and promotes the motility of these cells. These two effects are mediated through different mechanisms. The loss of phenotype effect is independent and the cell motility effect is dependent on calcium signaling.
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99
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Sano H, Kikuta J, Furuya M, Kondo N, Endo N, Ishii M. Intravital bone imaging by two-photon excitation microscopy to identify osteocytic osteolysis in vivo. Bone 2015; 74:134-9. [PMID: 25624000 DOI: 10.1016/j.bone.2015.01.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 01/13/2015] [Accepted: 01/21/2015] [Indexed: 10/24/2022]
Abstract
Bone is a highly dynamic organ in which several cell types function cooperatively. Among these, osteocytes have recently emerged as an important regulator of bone homeostasis, although their mechanism of regulation is unclear. Here, intravital bone imaging by two-photon excitation microscopy allowed us to directly visualize 'osteocytic osteolysis', or resorption of bone in the lacuno-canalicular system. Osteocyte lacunae and the canalicular network in the cortex of murine tibiae were imaged by in vivo calcein staining, and local acidification in these structures was monitored using a topically applied pH sensor. We also demonstrated that sciatic neurectomy causes significant acidification around osteocytic lacunae and enlargement of lacuno-canalicular areas. These results provide strong evidence for osteocytic osteolysis, and demonstrate that two-photon intravital microscopy is useful for analysis of this phenomenon.
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Affiliation(s)
- Hiroshige Sano
- Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, Osaka, Japan; Department of Orthopedic Surgery, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Junichi Kikuta
- Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, Osaka, Japan; WPI-Immunology Frontier Research Center, Osaka University, Osaka, Japan; JST, CREST, Tokyo, Japan
| | - Masayuki Furuya
- Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, Osaka, Japan; WPI-Immunology Frontier Research Center, Osaka University, Osaka, Japan
| | - Naoki Kondo
- Department of Orthopedic Surgery, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Naoto Endo
- Department of Orthopedic Surgery, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Masaru Ishii
- Department of Immunology and Cell Biology, Graduate School of Medicine and Frontier Biosciences, Osaka University, Osaka, Japan; WPI-Immunology Frontier Research Center, Osaka University, Osaka, Japan; JST, CREST, Tokyo, Japan.
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100
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Asamiya Y, Yajima A, Shimizu S, Otsubo S, Tsuchiya K, Nitta K. Associations between the levels of sclerostin, phosphate, and fibroblast growth factor-23 and treatment with vitamin D in hemodialysis patients with low intact PTH level. Osteoporos Int 2015; 26:1017-28. [PMID: 25366373 DOI: 10.1007/s00198-014-2934-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 09/15/2014] [Indexed: 12/30/2022]
Abstract
UNLABELLED Serum sclerostin levels could be closely associated with serum phosphate and fibroblast growth factor-23 levels in hemodialysis patients with low intact parathyroid hormone (PTH) levels. Further study is required to indicate whether these close associations are present in patients with spontaneously low PTH levels without any vitamin D treatment. INTRODUCTION Intact parathyroid hormone (iPTH) is involved in the interaction between sclerostin and phosphate/fibroblast growth factor-23 (FGF23) in animal models. However, their relationship in patients on hemodialysis (HD) is unclear. METHODS Data of 102 HD patients were collected regarding clinical and laboratory parameters and mineral bone disorder medications. The patients were divided into subgroups according to the iPTH level (A, <70 pg/mL; B, 70-150 pg/mL; C, 150-300 pg/mL; and D, ≥ 300 pg/mL). RESULTS The sclerostin level was significantly and positively correlated with phosphate and log of FGF23 levels in subgroups A, B, and combined A and B. Multiple linear regression analysis in the combined A and B subgroup revealed that male sex (t = 3.24, P = 0.01; 95% confidence interval [CI] 11.78 to 50.43) and phosphate level (t = 2.13, P = 0.04; 95% CI, 1.08 to 36.91) were independent factors for serum sclerostin level. The log of serum FGF23 level (t = 1.90, P = 0.06, 95% CI -1.85 to 63.50) appeared to be an important factor for serum sclerostin level. The frequency of patients using vitamin D treatment was not significantly different among subgroups A (93.1%), B (88.0%), C (85.2%), and D (90.5%). CONCLUSION Serum sclerostin levels were associated with serum phosphate and FGF23 levels in patients with low iPTH levels. Further study is required to indicate whether these close associations are present in patients with spontaneously low iPTH levels without vitamin D treatment.
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Affiliation(s)
- Y Asamiya
- Department of Medicine, Kidney Center, Tokyo Women's Medical University, 8-1 Kawada-chou, Shinjuku-ku, Tokyo, 162-8666, Japan,
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