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Rubin MR, Dhaliwal R. Role of advanced glycation endproducts in bone fragility in type 1 diabetes. Bone 2024; 178:116928. [PMID: 37802378 DOI: 10.1016/j.bone.2023.116928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 09/28/2023] [Accepted: 10/03/2023] [Indexed: 10/10/2023]
Abstract
The excess fracture risk observed in adults with type 1 diabetes (T1D) is inexplicable in the presence of only modest reductions in areal bone mineral density (BMD). Accumulation of advanced glycation endproducts (AGEs) in bone has been invoked as one explanation for the increased bone fragility in diabetes. The evidence linking AGEs and fractures in individuals with T1D is sparse, although the association has been observed in individuals with type 2 diabetes. Recent data show that in T1D, AGEs as measured by skin intrinsic fluorescence, are a risk factor for lower BMD. Further research in T1D is needed to ascertain whether there is a causal relationship between fractures and AGEs. If confirmed, this would pave the way for finding interventions that can slow AGE accumulation and thus reduce fractures in T1D.
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Affiliation(s)
- Mishaela R Rubin
- Metabolic Bone Disease Unit, Vagelos College of Physicians & Surgeons, Columbia University Irving Medical Center, United States of America
| | - Ruban Dhaliwal
- Division of Endocrinology, Department of Internal Medicine, The University of Texas Southwestern Medical Center, United States of America.
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2
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Bolger MW, Tekkey T, Kohn DH. The Contribution of Perilacunar Composition and Mechanical Properties to Whole-Bone Mechanical Outcomes in Streptozotocin-Induced Diabetes. Calcif Tissue Int 2023; 113:229-245. [PMID: 37261462 PMCID: PMC11144452 DOI: 10.1007/s00223-023-01098-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 05/18/2023] [Indexed: 06/02/2023]
Abstract
Osteocytes are the most abundant cell type in bone and remodel their local perilacunar matrix in response to a variety of stimuli and diseases. How the perilacunar composition and mechanical properties are affected by type 1 diabetes (T1D), and the contribution of these local changes to the decline in whole-bone functional properties that occurs with diabetes remains unclear. 12-14 week old C57/BL6 male mice were administered a series of low-dose streptozotocin injections and sacrificed at baseline (BL), 3 (D3) and 7 weeks (D7) following confirmation of diabetes, along with age-matched controls (C3, C7). Femora were then subjected to a thorough morphological (μCT), mechanical (four-point bending, nanoindentation), and compositional (HPLC for collagen cross-links, Raman spectroscopy) analysis at the whole-bone and local (perilacunar and intracortical) levels. At the whole-bone level, D7 mice exhibited 10.7% lower ultimate load and 26.4% lower post-yield work relative to C7. These mechanical changes coincided with 52.2% higher levels of pentosidine at D7 compared to C7. At the local level, the creep distance increased, while modulus and hardness decreased in the perilacunar region relative to the intracortical for D7 mice, suggesting a spatial uncoupling in skeletal adaptation. D7 mice also exhibited increased matrix maturity in the 1660/1690 cm-1 ratio at both regions relative to C7. The perilacunar matrix maturity was predictive of post-yield work (46%), but perilacunar measures were not predictive of ultimate load, which was better explained by cortical area (26%). These results show that diabetes causes local perilacunar composition perturbations that affect whole-bone level mechanical properties, implicating osteocyte maintenance of its local matrix in the progression of diabetic skeletal fragility.
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Affiliation(s)
- Morgan W Bolger
- Department of Biomedical Engineering, College of Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Tara Tekkey
- Department of Chemistry, College of Literature, Science and the Arts, University of Michigan, Ann Arbor, MI, USA
| | - David H Kohn
- Department of Biomedical Engineering, College of Engineering, University of Michigan, Ann Arbor, MI, USA.
- Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, 1011 N. University Ave., Ann Arbor, MI, 48109, USA.
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3
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Quadros KRS, Roza NAV, França RA, Esteves ABA, Barreto J, Dominguez WV, Furukawa LNS, Caramori JT, Sposito AC, de Oliveira RB. Advanced Glycation End Products and Bone Metabolism in Patients with Chronic Kidney Disease. JBMR Plus 2023; 7:e10727. [PMID: 36936360 PMCID: PMC10020922 DOI: 10.1002/jbm4.10727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 01/13/2023] [Indexed: 01/30/2023] Open
Abstract
Advanced glycation end products (AGEs) accumulation may be involved in the progression of CKD-bone disorders. We sought to determine the relationship between AGEs measured in the blood, skin, and bone with histomorphometry parameters, bone protein, gene expression, and serum biomarkers of bone metabolism in patients with CKD stages 3 to 5D patients. Serum levels of AGEs were estimated by pentosidine, glycated hemoglobin (A1c), and N-carboxymethyl lysine (CML). The accumulation of AGEs in the skin was estimated from skin autofluorescence (SAF). Bone AGEs accumulation and multiligand receptor for AGEs (RAGEs) expression were evaluated by immunohistochemistry; bone samples were used to evaluate protein and gene expression and histomorphometric analysis. Data are from 86 patients (age: 51 ± 13 years; 60 [70%] on dialysis). Median serum levels of pentosidine, CML, A1c, and SAF were 71.6 pmol/mL, 15.2 ng/mL, 5.4%, and 3.05 arbitrary units, respectively. AGEs covered 3.92% of trabecular bone and 5.42% of the cortical bone surface, whereas RAGEs were expressed in 0.7% and 0.83% of trabecular and cortical bone surfaces, respectively. AGEs accumulation in bone was inversely related to serum receptor activator of NF-κB ligand/parathyroid hormone (PTH) ratio (R = -0.25; p = 0.03), and RAGE expression was negatively related to serum tartrate-resistant acid phosphatase-5b/PTH (R = -0.31; p = 0.01). Patients with higher AGEs accumulation presented decreased bone protein expression (sclerostin [1.96 (0.11-40.3) vs. 89.3 (2.88-401) ng/mg; p = 0.004]; Dickkopf-related protein 1 [0.064 (0.03-0.46) vs. 1.36 (0.39-5.87) ng/mg; p = 0.0001]; FGF-23 [1.07 (0.4-32.6) vs. 44.1 (6-162) ng/mg; p = 0.01]; and osteoprotegerin [0.16 (0.08-2.4) vs. 6.5 (1.1-23.7) ng/mg; p = 0.001]), upregulation of the p53 gene, and downregulation of Dickkopf-1 gene expression. Patients with high serum A1c levels presented greater cortical porosity and Mlt and reduced osteoblast surface/bone surface, eroded surface/bone surface, osteoclast surface/bone surface, mineral apposition rate, and adjusted area. Cortical thickness was negatively correlated with serum A1c (R = -0.28; p = 0.02) and pentosidine levels (R = -0.27; p = 0.02). AGEs accumulation in the bone of CKD patients was related to decreased bone protein expression, gene expression changes, and increased skeletal resistance to PTH; A1c and pentosidine levels were related to decreased cortical thickness; and A1c levels were related to increased cortical porosity and Mlt. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Kélcia R. S. Quadros
- Nephrology Division, School of Medical SciencesUniversity of Campinas (Unicamp)CampinasBrazil
- Laboratory for Evaluation of Mineral and Bone Disorders in Nephrology (LEMON), School of Medical SciencesUniversity of Campinas (Unicamp)CampinasBrazil
| | - Noemi A. V. Roza
- Nephrology Division, School of Medical SciencesUniversity of Campinas (Unicamp)CampinasBrazil
- Laboratory for Evaluation of Mineral and Bone Disorders in Nephrology (LEMON), School of Medical SciencesUniversity of Campinas (Unicamp)CampinasBrazil
| | - Renata A. França
- Laboratory for Evaluation of Mineral and Bone Disorders in Nephrology (LEMON), School of Medical SciencesUniversity of Campinas (Unicamp)CampinasBrazil
| | - André B. A. Esteves
- Laboratory for Evaluation of Mineral and Bone Disorders in Nephrology (LEMON), School of Medical SciencesUniversity of Campinas (Unicamp)CampinasBrazil
| | - Joaquim Barreto
- Laboratory for Evaluation of Mineral and Bone Disorders in Nephrology (LEMON), School of Medical SciencesUniversity of Campinas (Unicamp)CampinasBrazil
| | - Wagner V. Dominguez
- Laboratory of Renal Pathophysiology, LIM‐16, Department of Internal Medicine, School of MedicineUniversity of São PauloSão PauloBrazil
| | - Luzia N. S. Furukawa
- Laboratory of Renal Pathophysiology, LIM‐16, Department of Internal Medicine, School of MedicineUniversity of São PauloSão PauloBrazil
| | | | - Andrei C. Sposito
- Laboratory of Atherosclerosis and Vascular Biology, Cardiology DivisionSchool of Medical Sciences, University of Campinas (Unicamp)CampinasBrazil
| | - Rodrigo Bueno de Oliveira
- Nephrology Division, School of Medical SciencesUniversity of Campinas (Unicamp)CampinasBrazil
- Laboratory for Evaluation of Mineral and Bone Disorders in Nephrology (LEMON), School of Medical SciencesUniversity of Campinas (Unicamp)CampinasBrazil
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Marcucci G, Domazetovic V, Nediani C, Ruzzolini J, Favre C, Brandi ML. Oxidative Stress and Natural Antioxidants in Osteoporosis: Novel Preventive and Therapeutic Approaches. Antioxidants (Basel) 2023; 12:antiox12020373. [PMID: 36829932 PMCID: PMC9952369 DOI: 10.3390/antiox12020373] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/27/2023] [Accepted: 01/30/2023] [Indexed: 02/09/2023] Open
Abstract
This review reports in detail the cellular and molecular mechanisms which regulate the bone remodeling process in relation to oxidative stress (OS), inflammatory factors, and estrogen deficiency. OS is considered an important pathogenic factor of osteoporosis, inducing osteocyte apoptosis and varying levels of specific factors, such as receptor activator κB ligand (RANKL), sclerostin, and, according to recent evidence, fibroblast growth factor 23, with consequent impairment of bone remodeling and high bone resorption. Bone loss increases the risk of fragility fractures, and the most commonly used treatments are antiresorptive drugs, followed by anabolic drugs or those with a double effect. In addition, recent data show that natural antioxidants contained in the diet are efficient in preventing and reducing the negative effects of OS on bone remodeling and osteocytes through the involvement of sirtuin type 1 enzyme. Indeed, osteocytes and some of their molecular factors are considered potential biological targets on which antioxidants can act to prevent and reduce bone loss, as well as to promote bone anabolic and regenerative processes by restoring physiological bone remodeling. Several data suggest including antioxidants in novel therapeutic approaches to develop better management strategies for the prevention and treatment of osteoporosis and OS-related bone diseases. In particular, anthocyanins, as well as resveratrol, lycopene, oleuropein, some vitamins, and thiol antioxidants, could have protective and therapeutic anti-osteoporotic effects.
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Affiliation(s)
- Gemma Marcucci
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
| | - Vladana Domazetovic
- Department of Paediatric Haematology-Oncology, Meyer Children’s Hospital IRCCS, 50139 Florence, Italy
| | - Chiara Nediani
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
- Correspondence:
| | - Jessica Ruzzolini
- Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy
| | - Claudio Favre
- Department of Paediatric Haematology-Oncology, Meyer Children’s Hospital IRCCS, 50139 Florence, Italy
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Cheng K, Guo Q, Yang W, Wang Y, Sun Z, Wu H. Mapping Knowledge Landscapes and Emerging Trends of the Links Between Bone Metabolism and Diabetes Mellitus: A Bibliometric Analysis From 2000 to 2021. Front Public Health 2022; 10:918483. [PMID: 35719662 PMCID: PMC9204186 DOI: 10.3389/fpubh.2022.918483] [Citation(s) in RCA: 46] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 05/16/2022] [Indexed: 01/09/2023] Open
Abstract
BackgroundDiabetes mellitus (DM) have become seriously threatens to human health and life quality worldwide. As a systemic metabolic disease, multiple studies have revealed that DM is related to metabolic bone diseases and always induces higher risk of fracture. In view of this, the links between bone metabolism (BM) and DM (BMDM) have gained much attention and numerous related papers have been published. Nevertheless, no prior studies have yet been performed to analyze the field of BMDM research through bibliometric approach. To fill this knowledge gap, we performed a comprehensive bibliometric analysis of the global scientific publications in this field.MethodsArticles and reviews regarding BMDM published between 2000 and 2021 were obtained from the Web of Science after manually screening. VOSviewer 1.6.16, CiteSpace V 5.8.R3, Bibliometrix, and two online analysis platforms were used to conduct the bibliometric and visualization analyses.ResultsA total of 2,525 documents including 2,255 articles and 270 reviews were retrieved. Our analysis demonstrated a steady increasing trend in the number of publications over the past 22 years (R2 = 0.989). The United States has occupied the leading position with the largest outputs and highest H-index. University of California San Francisco contributed the most publications, and Schwartz AV was the most influential author. Collaboration among institutions from different countries was relatively few. The journals that published the most BMDM-related papers were Bone and Osteoporosis International. Osteoporosis and related fractures are the main bone metabolic diseases of greatest concern in this field. According to co-cited references result, “high glucose environment,” “glycation end-product” and “sodium-glucose co-transporter” have been recognized as the current research focus in this domain. The keywords co-occurrence analysis indicated that “diabetic osteoporosis,” “osteoarthritis,” “fracture risk,” “meta-analysis,” “osteogenic differentiation,” “bone regeneration,” “osteogenesis,” and “trabecular bone score” might remain the research hotspots and frontiers in the near future.ConclusionAs a cross-discipline research field, the links between bone metabolism and diabetes mellitus are attracting increased attention. Osteoporosis and related fractures are the main bone metabolic diseases of greatest concern in this field. These insights may be helpful for clinicians to recognize diabetic osteopenia and provide more attention and support to such patients.
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Affiliation(s)
- Kunming Cheng
- Department of Intensive Care Unit, The Second Affiliated Hospital of Zhengzhou University, Zhengzhou, China
- Kunming Cheng
| | - Qiang Guo
- Department of Orthopaedic Surgery, Baodi Clinical College of Tianjin Medical University, Tianjin, China
| | - Weiguang Yang
- Graduate School of Tianjin Medical University, Tianjin, China
- Department of Orthopaedic Surgery, Clinical College of Neurology, Neurosurgery and Neurorehabilitation, Tianjin Medical University, Tianjin, China
| | - Yulin Wang
- Graduate School of Tianjin Medical University, Tianjin, China
- Department of Orthopaedic Surgery, Clinical College of Neurology, Neurosurgery and Neurorehabilitation, Tianjin Medical University, Tianjin, China
| | - Zaijie Sun
- Department of Orthopaedic Surgery, Xiangyang Central Hospital, Affiliated Hospital of Hubei University of Arts and Science, Xiangyang, China
- *Correspondence: Zaijie Sun
| | - Haiyang Wu
- Graduate School of Tianjin Medical University, Tianjin, China
- Department of Orthopaedic Surgery, Clinical College of Neurology, Neurosurgery and Neurorehabilitation, Tianjin Medical University, Tianjin, China
- Haiyang Wu
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Teissier T, Temkin V, Pollak RD, Cox LS. Crosstalk Between Senescent Bone Cells and the Bone Tissue Microenvironment Influences Bone Fragility During Chronological Age and in Diabetes. Front Physiol 2022; 13:812157. [PMID: 35388291 PMCID: PMC8978545 DOI: 10.3389/fphys.2022.812157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/27/2022] [Indexed: 01/10/2023] Open
Abstract
Bone is a complex organ serving roles in skeletal support and movement, and is a source of blood cells including adaptive and innate immune cells. Structural and functional integrity is maintained through a balance between bone synthesis and bone degradation, dependent in part on mechanical loading but also on signaling and influences of the tissue microenvironment. Bone structure and the extracellular bone milieu change with age, predisposing to osteoporosis and increased fracture risk, and this is exacerbated in patients with diabetes. Such changes can include loss of bone mineral density, deterioration in micro-architecture, as well as decreased bone flexibility, through alteration of proteinaceous bone support structures, and accumulation of senescent cells. Senescence is a state of proliferation arrest accompanied by marked morphological and metabolic changes. It is driven by cellular stress and serves an important acute tumor suppressive mechanism when followed by immune-mediated senescent cell clearance. However, aging and pathological conditions including diabetes are associated with accumulation of senescent cells that generate a pro-inflammatory and tissue-destructive secretome (the SASP). The SASP impinges on the tissue microenvironment with detrimental local and systemic consequences; senescent cells are thought to contribute to the multimorbidity associated with advanced chronological age. Here, we assess factors that promote bone fragility, in the context both of chronological aging and accelerated aging in progeroid syndromes and in diabetes, including senescence-dependent alterations in the bone tissue microenvironment, and glycation changes to the tissue microenvironment that stimulate RAGE signaling, a process that is accelerated in diabetic patients. Finally, we discuss therapeutic interventions targeting RAGE signaling and cell senescence that show promise in improving bone health in older people and those living with diabetes.
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Affiliation(s)
- Thibault Teissier
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | - Vladislav Temkin
- Division of Medicine, Department of Endocrinology and Metabolism, The Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Rivka Dresner Pollak
- Division of Medicine, Department of Endocrinology and Metabolism, The Hadassah Medical Center, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Lynne S. Cox
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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Broz K, Walk RE, Tang SY. Complications in the spine associated with type 2 diabetes: The role of advanced glycation end-products. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2021; 11. [PMID: 35992525 PMCID: PMC9390092 DOI: 10.1016/j.medntd.2021.100065] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Type 2 diabetes mellitus (T2D) is an increasingly prevalent disease with numerous comorbidities including many in the spine. T2D is strongly linked with vertebral fractures, intervertebral disc (IVD) degeneration, and severe chronic spinal pain. Yet the causative mechanism for these musculoskeletal impairments remains unclear. The chronic hyperglycemic state in T2D promotes the formation of advanced glycation end-products (AGEs) in tissues, and the accumulation of AGEs may play a role in musculoskeletal complications by modifying the extracellular matrix, impairing cellular homeostasis, and perpetuating an inflammatory cascade via its receptor (RAGE). The AGE and RAGE associated alterations in extracellular matrix composition and morphological features of the vertebral bodies and IVDs are likely contributors to the incidence and severity of spinal pathologies in T2D. This review will broadly examine the effects of AGEs on tissues in the spine in the context of T2D, with an emphasis on the changes in the vertebrae and the IVD. Along with the clinical and epidemiological findings, we will provide an overview of preclinical rodent models of T2D that exhibit deficits in the IVD and vertebral bone. Elucidating the role of AGEs and RAGE will be crucial for understanding the disease mechanisms and translation therapies of musculoskeletal pathologies in T2D.
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Affiliation(s)
- Kaitlyn Broz
- Institute of Material Science and Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Remy E. Walk
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Simon Y. Tang
- Institute of Material Science and Engineering, Washington University in St. Louis, St. Louis, MO, USA
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
- Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO, USA
- Corresponding author. Department of Orthopaedic Surgery, Washington University in St. Louis, School of Medicine, 660 S. Euclid Avenue, Campus Box 8233, St. Louis, MO, 63110, USA. (S.Y. Tang)
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8
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Wang YY, Xia K, Wang ZX, Xie H, Xu R. Osteocyte exosomes accelerate benign prostatic hyperplasia development. Mol Cell Endocrinol 2021; 531:111301. [PMID: 33933560 DOI: 10.1016/j.mce.2021.111301] [Citation(s) in RCA: 2] [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: 12/14/2020] [Revised: 04/05/2021] [Accepted: 04/22/2021] [Indexed: 12/22/2022]
Abstract
Benign prostatic hyperplasia (BPH) is one of the most common diseases in elderly men. BPH patients exhibit an increased risk of vertebral and hip fractures, which are most attributable to pre-existing osteoporosis. However, the relationship between BPH and osteoporosis is still unknown. Here we found that osteocytes, the most abundant bone cells, promoted BPH development by secreting exosomes. In vitro, osteocyte exosomes (OCY-Exo) directly promoted cell proliferation of a prostate epithelial cell line BPH-1 and a macrophage cell line RAW264.7, OCY-Exo also stimulated macrophage-induced proliferation of BPH-1 cells. In vivo, intramedullary injection of OCY-Exo accumulated in prostate. Intravenous administration of OCY-Exo exacerbated testosterone-induced BPH in C57BL/6J mice. Our study uncovers the role of OCY-Exo as a stimulator of BPH, suggesting a novel mechanism in bone-prostate communication.
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Affiliation(s)
- Yi-Yi Wang
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Kun Xia
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhen-Xing Wang
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Hui Xie
- Department of Orthopedics, Movement System Injury and Repair Research Center, Xiangya Hospital, Central South University, Changsha, Hunan, China.
| | - Ran Xu
- Department of Urology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
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9
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Huang X, Xie M, Xie Y, Mei F, Lu X, Li X, Chen L. The roles of osteocytes in alveolar bone destruction in periodontitis. J Transl Med 2020; 18:479. [PMID: 33308247 PMCID: PMC7733264 DOI: 10.1186/s12967-020-02664-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023] Open
Abstract
Periodontitis, a bacterium-induced inflammatory disease that is characterized by alveolar bone loss, is highly prevalent worldwide. Elucidating the underlying mechanisms of alveolar bone loss in periodontitis is crucial for understanding its pathogenesis. Classically, bone cells, such as osteoclasts, osteoblasts and bone marrow stromal cells, are thought to dominate the development of bone destruction in periodontitis. Recently, osteocytes, the cells embedded in the mineral matrix, have gained attention. This review demonstrates the key contributing role of osteocytes in periodontitis, especially in alveolar bone loss. Osteocytes not only initiate physiological bone remodeling but also assist in inflammation-related changes in bone remodeling. The latest evidence suggests that osteocytes are involved in regulating bone anabolism and catabolism in the progression of periodontitis. The altered secretion of receptor activator of NF-κB ligand (RANKL), sclerostin and Dickkopf-related protein 1 (DKK1) by osteocytes affects the balance of bone resorption and formation and promotes bone loss. In addition, the accumulation of prematurely senescent and apoptotic osteocytes observed in alveolar bone may exacerbate local destruction. Based on their communication with the bloodstream, it is noteworthy that osteocytes may participate in the interaction between local periodontitis lesions and systemic diseases. Overall, further investigations of osteocytes may provide vital insights that improve our understanding of the pathophysiology of periodontitis.
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Affiliation(s)
- Xiaofei Huang
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.,Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, 430022, China
| | - Mengru Xie
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.,Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, 430022, China
| | - Yanling Xie
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.,Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, 430022, China
| | - Feng Mei
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.,Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, 430022, China
| | - Xiaofeng Lu
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.,Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, 430022, China
| | - Xiaoshuang Li
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China. .,Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, 430022, China.
| | - Lili Chen
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China. .,Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, 430022, China.
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10
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Piccoli A, Cannata F, Strollo R, Pedone C, Leanza G, Russo F, Greto V, Isgrò C, Quattrocchi CC, Massaroni C, Silvestri S, Vadalà G, Bisogno T, Denaro V, Pozzilli P, Tang SY, Silva MJ, Conte C, Papalia R, Maccarrone M, Napoli N. Sclerostin Regulation, Microarchitecture, and Advanced Glycation End-Products in the Bone of Elderly Women With Type 2 Diabetes. J Bone Miner Res 2020; 35:2415-2422. [PMID: 32777114 PMCID: PMC8143610 DOI: 10.1002/jbmr.4153] [Citation(s) in RCA: 72] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 07/21/2020] [Accepted: 08/02/2020] [Indexed: 12/21/2022]
Abstract
Increased circulating sclerostin and accumulation of advanced glycation end-products (AGEs) are two potential mechanisms underlying low bone turnover and increased fracture risk in type 2 diabetes (T2D). Whether the expression of the sclerostin-encoding SOST gene is altered in T2D, and whether it is associated with AGEs accumulation or regulation of other bone formation-related genes is unknown. We hypothesized that AGEs accumulate and SOST gene expression is upregulated in bones from subjects with T2D, leading to downregulation of bone forming genes (RUNX2 and osteocalcin) and impaired bone microarchitecture and strength. We obtained bone tissue from femoral heads of 19 T2D postmenopausal women (mean glycated hemoglobin [HbA1c] 6.5%) and 73 age- and BMI-comparable nondiabetic women undergoing hip replacement surgery. Despite similar bone mineral density (BMD) and biomechanical properties, we found a significantly higher SOST (p = .006) and a parallel lower RUNX2 (p = .025) expression in T2D compared with non-diabetic subjects. Osteocalcin gene expression did not differ between T2D and non-diabetic subjects, as well as circulating osteocalcin and sclerostin levels. We found a 1.5-fold increase in total bone AGEs content in T2D compared with non-diabetic women (364.8 ± 78.2 versus 209.9 ± 34.4 μg quinine/g collagen, respectively; p < .001). AGEs bone content correlated with worse bone microarchitecture, including lower volumetric BMD (r = -0.633; p = .02), BV/TV (r = -0.59; p = .033) and increased trabecular separation/spacing (r = 0.624; p = .023). In conclusion, our data show that even in patients with good glycemic control, T2D affects the expression of genes controlling bone formation (SOST and RUNX2). We also found that accumulation of AGEs is associated with impaired bone microarchitecture. We provide novel insights that may help understand the mechanisms underlying bone fragility in T2D. © 2020 American Society for Bone and Mineral Research (ASBMR).
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Affiliation(s)
- Alessandra Piccoli
- Unit of Endocrinology and Diabetes, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy.,Unit of Biochemistry and Molecular Biology, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Francesca Cannata
- Unit of Endocrinology and Diabetes, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Rocky Strollo
- Unit of Endocrinology and Diabetes, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Claudio Pedone
- Unit of Geriatrics, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Giulia Leanza
- Unit of Endocrinology and Diabetes, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Fabrizio Russo
- Unit of Orthopedic and Trauma Surgery, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Valentina Greto
- Unit of Endocrinology and Diabetes, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Camilla Isgrò
- Department of Basic Medical Sciences, Neurosciences and Sensory Organs, University of Bari "Aldo Moro", Bari, Italy
| | | | - Carlo Massaroni
- Research Unit of Measurements and Biomedical Instrumentation, Departmental Faculty of Bioengineering, Campus Bio-Medico di Roma University, Rome, Italy
| | - Sergio Silvestri
- Research Unit of Measurements and Biomedical Instrumentation, Departmental Faculty of Bioengineering, Campus Bio-Medico di Roma University, Rome, Italy
| | - Gianluca Vadalà
- Unit of Orthopedic and Trauma Surgery, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Tiziana Bisogno
- Endocannabinoid Research Group, Institute of Translational Pharmacology, National Research Council, (CNR), Rome, Italy
| | - Vincenzo Denaro
- Unit of Orthopedic and Trauma Surgery, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Paolo Pozzilli
- Unit of Endocrinology and Diabetes, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Simon Y Tang
- Unit of Orthopedics, Washington University in St. Louis, St. Louis, MO, USA
| | - Matt J Silva
- Unit of Orthopedics, Washington University in St. Louis, St. Louis, MO, USA
| | - Caterina Conte
- Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy
| | - Rocco Papalia
- Unit of Orthopedic and Trauma Surgery, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy
| | - Mauro Maccarrone
- Unit of Biochemistry and Molecular Biology, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy.,European Center for Brain Research (CERC)/Santa Lucia Foundation, Rome, Italy
| | - Nicola Napoli
- Unit of Endocrinology and Diabetes, Departmental Faculty of Medicine and Surgery, Campus Bio-Medico University of Rome, Rome, Italy.,Division of Bone and Mineral Diseases, Washington University in St. Louis, St. Louis, MO, USA
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11
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Osteocyte apoptosis: the roles and key molecular mechanisms in resorption-related bone diseases. Cell Death Dis 2020; 11:846. [PMID: 33046704 PMCID: PMC7552426 DOI: 10.1038/s41419-020-03059-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 09/23/2020] [Accepted: 09/24/2020] [Indexed: 01/18/2023]
Abstract
Vital osteocytes have been well known to function as an important orchestrator in the preservation of robustness and fidelity of the bone remodeling process. Nevertheless, some key pathological factors, such as sex steroid deficiency and excess glucocorticoids, and so on, are implicated in inducing a bulk of apoptotic osteocytes, subsequently resulting in resorption-related bone loss. As much, osteocyte apoptosis, under homeostatic conditions, is in an optimal state of balance tightly controlled by pro- and anti-apoptotic mechanism pathways. Importantly, there exist many essential signaling proteins in the process of osteocyte apoptosis, which has a crucial role in maintaining a homeostatic environment. While increasing in vitro and in vivo studies have established, in part, key signaling pathways and cross-talk mechanism on osteocyte apoptosis, intrinsic and complex mechanism underlying osteocyte apoptosis occurs in various states of pathologies remains ill-defined. In this review, we discuss not only essential pro- and anti-apoptotic signaling pathways and key biomarkers involved in these key mechanisms under different pathological agents, but also the pivotal role of apoptotic osteocytes in osteoclastogenesis-triggered bone loss, hopefully shedding new light on the attractive and proper actions of pharmacotherapeutics of targeting apoptosis and ensuing resorption-related bone diseases such as osteoporosis and fragility fractures.
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12
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Suzuki A, Yabu A, Nakamura H. Advanced glycation end products in musculoskeletal system and disorders. Methods 2020; 203:179-186. [PMID: 32987130 DOI: 10.1016/j.ymeth.2020.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/18/2020] [Accepted: 09/23/2020] [Indexed: 02/06/2023] Open
Abstract
The human population is ageing globally, and the number of old people is increasing yearly. Diabetes is common in the elderly, and the number of diabetic patients is also increasing. Elderly and diabetic patients often have musculoskeletal disorder, which are associated with advanced glycation end products (AGEs). AGEs are heterogeneous molecules derived from non-enzymatic products of the reaction of glucose or other sugar derivatives with proteins or lipids, and many different types of AGEs have been identified. AGEs are a biomarker for ageing and for evaluating disease conditions. Fluorescence, spectroscopy, mass spectrometry, chromatography, and immunological methods are commonly used to measure AGEs, but there is no standardized evaluation method because of the heterogeneity of AGEs. The formation of AGEs is irreversible, and they accumulate in tissue, eventually causing damage. AGE accumulation has been confirmed in neuromusculoskeletal tissues, including bones, cartilage, muscles, tendons, ligaments, and nerves, where they adversely affect biomechanical properties by causing charge changes and forming cross-linkages. AGEs also bind to receptors, such as the receptor for AGEs (RAGE), and induce inflammation by intracellular signal transduction. These mechanisms cause many varied aging and diabetes-related pathological conditions, such as osteoporosis, osteoarthritis, sarcopenia, tendinopathy, and neuropathy. Understanding of AGEs related pathomechanism may lead to develop novel methods for the prevention and therapy of such disorders which affect patients' quality of life. Herein, we critically review the current methodology used for detecting AGEs, and present potential mechanisms by which AGEs cause or exacerbate musculoskeletal disorders.
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Affiliation(s)
- Akinobu Suzuki
- Department of Orthopedic Surgery, Osaka City University Graduate School of Medicine, Japan.
| | - Akito Yabu
- Department of Orthopedic Surgery, Osaka City University Graduate School of Medicine, Japan
| | - Hiroaki Nakamura
- Department of Orthopedic Surgery, Osaka City University Graduate School of Medicine, Japan
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13
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Zhao D, Liu R, Li G, Chen M, Shang P, Yang H, Jiang JX, Xu H. Connexin 43 Channels in Osteocytes Regulate Bone Responses to Mechanical Unloading. Front Physiol 2020; 11:299. [PMID: 32296345 PMCID: PMC7137730 DOI: 10.3389/fphys.2020.00299] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 03/16/2020] [Indexed: 01/01/2023] Open
Abstract
Connexin (Cx) 43 forms gap junctions and hemichannels that mediate communication between osteocytes and adjacent cells or the extracellular environment in bone, respectively. To investigate the role of each channel type in response to mechanical unloading, two transgenic mouse models overexpressing dominant-negative Cx43 predominantly in osteocytes driven by a 10 kb dentin matrix protein 1 (Dmp1) promoter were generated. The R76W mutation resulted in gap junction inhibition and enhancement of hemichannels, whereas the Δ130-136 mutation inhibited both gap junctions and hemichannels. Both mutations led to cortical bone loss with increased endocortical osteoclast activity during unloading. Increased periosteal osteoclasts with decreased apoptotic osteocytes were observed only in R76W mice. These findings indicated that inhibiting osteocytic Cx43 channels promotes bone loss induced by unloading, mainly in the cortical area; moreover, hemichannels protect osteocytes against apoptosis and promote periosteal bone remodeling, whereas gap junctions modulate endocortical osteoclast activity in response to unloading.
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Affiliation(s)
- Dezhi Zhao
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Ruofei Liu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Guobin Li
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Meng Chen
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
| | - Peng Shang
- Key Laboratory for Space Bioscience and Biotechnology, Research and Development Institute in Shenzhen, Northwestern Polytechnical University, Shenzhen, China
| | - Hui Yang
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
- Research Center of Special Environmental Biomechanics and Medical Engineering, Northwestern Polytechnical University, Xi’an, China
| | - Jean X. Jiang
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center, San Antonio, TX, United States
| | - Huiyun Xu
- Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi’an, China
- Key Laboratory for Space Bioscience and Biotechnology, Research and Development Institute in Shenzhen, Northwestern Polytechnical University, Shenzhen, China
- Research Center of Special Environmental Biomechanics and Medical Engineering, Northwestern Polytechnical University, Xi’an, China
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14
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Zhou S, Zhao D, Liu S, Zeng W, Zhang C. TGF-β1 sustains germ cell cyst reservoir via restraining follicle formation in the chicken. Cell Biol Int 2019; 44:861-872. [PMID: 31825139 DOI: 10.1002/cbin.11283] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Accepted: 12/09/2019] [Indexed: 01/04/2023]
Abstract
The transforming growth factor β (TGF-β) superfamily members are important molecules that regulate many ovarian functions under normal physiological and pathological conditions. TGF-β1 and its receptors are highly expressed in the ovarian cells of many species. However, the effect of TGF-β1 on the capacity of the avian germ cell reservoir remains unknown. In this study, 5-day-old chicks were injected with TGF-β1 (2.5, 12.5, and 62.5 μg/kg body weight) for 3 days to assess the effect of TGF-β1 on early follicle development. Morphological analysis showed that treatment with TGF-β1 (12.5 μg/kg) increased the number of germ cell cysts and reduced the number of primordial and growing follicles. The diameter and area of oocytes and follicles were decreased after TGF-β1 treatment. Immunohistochemical staining of the proliferating cell nuclear antigen revealed that the ratios of the positive somatic and granulosa cells were decreased by 16.2% and 2.48%, respectively. Furthermore, more apoptotic cells were observed in the TGF-β1 group than those of the control by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. In addition, we cultured the 5d chicken ovaries for 3 days in vitro and found that treatment with TGF-β1 (10 ng/mL) manifested similar results as the in vivo experiment. However, the negative effect of TGF-β1 on early ovary development was rescued by treatment with a TGF-βR1 inhibitor SD208, resulting in increased expression of steroidogenic enzymes and cell cycle-regulating proteins. In conclusion, TGF-β1 could maintain the germ cell reservoir by restraining follicle activation involving reduced cell proliferation and steroidogenic enzymes gene expression at the early stage of ovarian development.
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Affiliation(s)
- Shuo Zhou
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Dan Zhao
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, 310058, China.,Sichuan Institute of Veterinary Drug Control, Chengdu, 610041, China
| | - Shuqi Liu
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Weidong Zeng
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, 310058, China
| | - Caiqiao Zhang
- Department of Veterinary Medicine, College of Animal Sciences, Zhejiang University, Hangzhou, 310058, China
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15
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Dai J, Chen H, Chai Y. Advanced Glycation End Products (AGEs) Induce Apoptosis of Fibroblasts by Activation of NLRP3 Inflammasome via Reactive Oxygen Species (ROS) Signaling Pathway. Med Sci Monit 2019; 25:7499-7508. [PMID: 31587010 PMCID: PMC6792499 DOI: 10.12659/msm.915806] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Background Type 2 diabetes impairs the healing process and induces apoptosis of fibroblasts, which are thought to be involved in this process. We investigated the possible mechanisms involved in AGEs-induced apoptosis of human dermal fibroblasts. Material/Methods We examined the expression of apoptosis-related proteins in fibroblasts isolated from human diabetic wounds. Human dermal fibroblasts exposed to AGEs were used to study the links among apoptosis, ROS, and NLRP3 inflammasome activation. Signaling mechanisms were evaluated by preincubating the cells with appropriate inhibitors. Cleaved caspase-8, cleaved caspase-3, BAX, Bcl-2, and NLRP3 inflammasome expression were measured by Western blot analysis. ROS generation, cell viability, and cell apoptosis were assessed. Results We observed a higher level of cleaved caspase-8 and cleaved caspase-3 expression in fibroblasts isolated from human diabetic wounds compared with controls. AGEs decreased the proliferation of cells in a concentration-dependent and time-dependent manner. The exposure of fibroblasts to AGEs significantly increased the number of cells in early and late apoptosis stages. AGES-induced human dermal fibroblasts showed high expressions of cleaved caspase3, cleaved caspase8, and Bax. Treatment with AGEs induced the expression of NLRP3, caspase-1, and ASC. AGES-induced apoptosis was blocked by BAY 11–7082, an inhibitor of the NLRP3 inflammasome. AGEs increased the production of ROS in fibroblasts, and its apoptogenic effect was blocked by NAC. Conclusions AGEs cause apoptosis of fibroblasts by inducing the generation of ROS and activating the NLRP3 inflammasome. In vivo experiments are needed to confirm these results.
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Affiliation(s)
- Jiezhi Dai
- Department of Orthopedic Surgery, Shanghai Sixth People's Hospital, JiaoTong University, Shanghai, China (mainland)
| | - Hua Chen
- Department of Orthopedic Surgery, Shanghai Sixth People's Hospital, JiaoTong University, Shanghai, China (mainland)
| | - Yimin Chai
- Department of Orthopedic Surgery, Shanghai Sixth People's Hospital, JiaoTong University, Shanghai, China (mainland)
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16
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Notsu M, Kanazawa I, Takeno A, Tanaka KI, Sugimoto T. Bazedoxifene Ameliorates Homocysteine-Induced Apoptosis via NADPH Oxidase-Interleukin 1β and 6 Pathway in Osteocyte-like Cells. Calcif Tissue Int 2019; 105:446-457. [PMID: 31250042 DOI: 10.1007/s00223-019-00580-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 06/21/2019] [Indexed: 01/26/2023]
Abstract
Homocysteine (Hcy) increases oxidation and inflammation; however, the mechanism of Hcy-induced bone fragility remains unclear. Because selective estrogen modulators (SERMs) have an anti-oxidative effect, SERMs may rescue the Hcy-induced bone fragility. We aimed to examine whether oxidative stress and pro-inflammatory cytokines such as interleukin (IL)-1β and IL-6 are involved in the Hcy-induced apoptosis of osteocytes and whether bazedoxifene (BZA) inhibits the detrimental effects of Hcy. We used mouse osteocyte-like cell lines MLO-Y4-A2 and Ocy454. Apoptosis was examined by DNA fragmentation ELISA and TUNEL staining, and gene expression was evaluated by real-time PCR. Hcy 5 mM significantly increased expressions of NADPH oxidase (Nox)1, Nox2, IL-1β, and IL-6 as well as apoptosis in MLO-Y4-A2 cells. Nox inhibitors, diphenyleneiodonium chloride and apocynin, significantly suppressed Hcy-induced IL-1β and IL-6 expressions. In contrast, an IL-1β receptor antagonist and an IL-6 receptor monoclonal antibody had no effects on Hcy-induced Nox1 and Nox2 expressions, but significantly rescued Hcy-induced apoptosis. BZA (1 nM-1 μM) and 17β estradiol 100 nM significantly rescued Hcy-induced apoptosis, while an estrogen receptor blocker ICI 182,780 reversed the effects of BZA and 17β estradiol. BZA also rescued Hcy-induced apoptosis of Ocy454 cell, and ICI canceled the effect of BZD. Moreover, BZA significantly ameliorated Hcy-induced expressions of Nox1, Nox2, IL-1β, and IL-6, and ICI canceled the effects of BZA on their expressions. Hcy increases apoptosis through stimulating Nox 1 and Nox 2-IL-1β and IL-6 expressions in osteocyte-like cells. BZA inhibits the detrimental effects of Hcy on osteocytes via estrogen receptor.
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Affiliation(s)
- Masakazu Notsu
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Ippei Kanazawa
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan.
| | - Ayumu Takeno
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Ken-Ichiro Tanaka
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan
| | - Toshitsugu Sugimoto
- Internal Medicine 1, Shimane University Faculty of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan
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17
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Davis HM, Valdez S, Gomez L, Malicky P, White FA, Subler MA, Windle JJ, Bidwell JP, Bruzzaniti A, Plotkin LI. High mobility group box 1 protein regulates osteoclastogenesis through direct actions on osteocytes and osteoclasts in vitro. J Cell Biochem 2019; 120:16741-16749. [PMID: 31106449 DOI: 10.1002/jcb.28932] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/24/2019] [Indexed: 12/30/2022]
Abstract
Old age and Cx43 deletion in osteocytes are associated with increased osteocyte apoptosis and osteoclastogenesis. We previously demonstrated that apoptotic osteocytes release elevated concentrations of the proinflammatory cytokine, high mobility group box 1 protein (HMGB1) and apoptotic osteocyte conditioned media (CM) promotes osteoclast differentiation. Further, prevention of osteocyte apoptosis blocks osteoclast differentiation and attenuates the extracellular release of HMGB1 and RANKL. Moreover, sequestration of HMGB1, in turn, reduces RANKL production/release by MLO-Y4 osteocytic cells silenced for Cx43 (Cx43def ), highlighting the possibility that HMGB1 promotes apoptotic osteocyte-induced osteoclastogenesis. However, the role of HMGB1 signaling in osteocytes has not been well studied. Further, the mechanisms underlying its release and the receptor(s) responsible for its actions is not clear. We now report that a neutralizing HMGB1 antibody reduces osteoclast formation in RANKL/M-CSF treated bone marrow cells. In bone marrow macrophages (BMMs), toll-like receptor 4 (TLR4) inhibition with LPS-RS, but not receptor for advanced glycation end products (RAGE) inhibition with Azeliragon attenuated osteoclast differentiation. Further, inhibition of RAGE but not of TLR4 in osteoclast precursors reduced osteoclast number, suggesting that HGMB1 produced by osteoclasts directly affects differentiation by activating TLR4 in BMMs and RAGE in preosteoclasts. Our findings also suggest that increased osteoclastogenesis induced by apoptotic osteocytes CM is not mediated through HMGB1/RAGE activation and that direct HMGB1 actions in osteocytes stimulate pro-osteoclastogenic signal release from Cx43def osteocytes. Based on these findings, we propose that HMGB1 exerts dual effects on osteoclasts, directly by inducing differentiation through TLR4 and RAGE activation and indirectly by increasing pro-osteoclastogenic cytokine secretion from osteocytes.
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Affiliation(s)
- Hannah M Davis
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana.,Indiana Center for Musculoskeletal Health, Indianapolis, Indiana
| | - Sinai Valdez
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Leland Gomez
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Peter Malicky
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, Indiana
| | - Fletcher A White
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, Indiana.,Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana.,Roudebush Veterans Administration Medical Center, Indianapolis, Indiana
| | - Mark A Subler
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia
| | - Jolene J Windle
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia
| | - Joseph P Bidwell
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana.,Indiana Center for Musculoskeletal Health, Indianapolis, Indiana
| | - Angela Bruzzaniti
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana.,Indiana Center for Musculoskeletal Health, Indianapolis, Indiana.,Department of Biomedical and Applied Sciences, Indiana University School of Dentistry, Indianapolis, Indiana
| | - Lilian I Plotkin
- Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana.,Indiana Center for Musculoskeletal Health, Indianapolis, Indiana.,Roudebush Veterans Administration Medical Center, Indianapolis, Indiana
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18
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Sakamoto E, Kido JI, Takagi R, Inagaki Y, Naruishi K, Nagata T, Yumoto H. Advanced glycation end-product 2 and Porphyromonas gingivalis lipopolysaccharide increase sclerostin expression in mouse osteocyte-like cells. Bone 2019; 122:22-30. [PMID: 30735798 DOI: 10.1016/j.bone.2019.02.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 01/23/2019] [Accepted: 02/04/2019] [Indexed: 02/06/2023]
Abstract
Sclerostin is a secreted glycoprotein that is mainly expressed in osteocytes, exerts negative effects on bone formation, and is present at elevated levels in diabetes mellitus (DM). Periodontitis is an infectious disease caused by periodontopathic bacteria, a complication of DM, and sometimes associated with severe inflammation and alveolar bone resorption. Advanced glycation end-products (AGEs) are a major pathogen in DM complications and adversely influence periodontitis in DM patients. In the present study, the effects of AGE2 and Porphyromonas gingivalis lipopolysaccharide (P-LPS) on the expression of sclerostin in mouse osteocyte-like cells (MLO-Y4-A2 cells) and its function in osteoblast differentiation were investigated. AGE2 and P-LPS up-regulated the expressions of receptor of AGE (RAGE) and Toll-like receptor 2 (TLR2), respectively, and significantly up-regulated that of sclerostin and interleukin 6 (IL-6) in osteocytes. Sclerostin, RAGE and TLR2 levels were synergistically increased by AGE2 and P-LPS. The siRNAs of RAGE and TLR2 significantly inhibited AGE2- and P-LPS-induced sclerostin expression. AGE2 up-regulated sclerostin expression in osteocyte-like cells via the RAGE, ERK and JNK, and NF-κB signal pathways. On the other hand, P-LPS elevated sclerostin levels via the TLR2, JNK and p38, and NF-κB signal pathways. When osteocytes pre-treated with AGE2 and P-LPS and osteoblastic cells (MC3T3-E1) were co-cultured in the medium with a sclerostin-neutralizing antibody, AGE2- and P-LPS-induced decreases in alkaline phosphatase activity and Runx2 expression in osteoblastic cells were significantly inhibited by the sclerostin-neutralizing antibody. These results suggest that AGE2 and P-LPS influence bone metabolism and inflammation through the regulation of sclerostin expression, and may aggravate periodontitis with DM.
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Affiliation(s)
- Eijiro Sakamoto
- Department of Periodontology and Endodontology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Jun-Ichi Kido
- Department of Periodontology and Endodontology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan.
| | - Ryosuke Takagi
- Department of Periodontology and Endodontology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Yuji Inagaki
- Department of Periodontology and Endodontology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Koji Naruishi
- Department of Periodontology and Endodontology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Toshihiko Nagata
- Department of Periodontology and Endodontology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Hiromichi Yumoto
- Department of Periodontology and Endodontology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
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19
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Picke AK, Campbell G, Napoli N, Hofbauer LC, Rauner M. Update on the impact of type 2 diabetes mellitus on bone metabolism and material properties. Endocr Connect 2019; 8:R55-R70. [PMID: 30772871 PMCID: PMC6391903 DOI: 10.1530/ec-18-0456] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 01/24/2019] [Indexed: 11/23/2022]
Abstract
The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide, especially as a result of our aging society, high caloric intake and sedentary lifestyle. Besides the well-known complications of T2DM on the cardiovascular system, the eyes, kidneys and nerves, bone strength is also impaired in diabetic patients. Patients with T2DM have a 40-70% increased risk for fractures, despite having a normal to increased bone mineral density, suggesting that other factors besides bone quantity must account for increased bone fragility. This review summarizes the current knowledge on the complex effects of T2DM on bone including effects on bone cells, bone material properties and other endocrine systems that subsequently affect bone, discusses the effects of T2DM medications on bone and concludes with a model identifying factors that may contribute to poor bone quality and increased bone fragility in T2DM.
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Affiliation(s)
- Ann-Kristin Picke
- Institute of Comparative Molecular Endocrinology, Ulm University, Ulm, Germany
| | - Graeme Campbell
- Institute of Biomechanics, TUHH Hamburg University of Technology, Hamburg, Germany
| | - Nicola Napoli
- Diabetes and Bone Network, Department Endocrinology and Diabetes, University Campus Bio-Medico of Rome, Rome, Italy
- Division of Bone and Mineral Diseases, Washington University in St Louis, St Louis, Missouri, USA
| | - Lorenz C Hofbauer
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
| | - Martina Rauner
- Department of Medicine III & Center for Healthy Aging, Technische Universität Dresden, Dresden, Germany
- Correspondence should be addressed to M Rauner:
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20
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Abstract
PURPOSE OF REVIEW The receptor for advanced glycation end products (RAGE) and several of its ligands have been implicated in the onset and progression of pathologies associated with aging, chronic inflammation, and cellular stress. In particular, the role of RAGE and its ligands in bone tissue during both physiological and pathological conditions has been investigated. However, the extent to which RAGE signaling regulates bone homeostasis and disease onset remains unclear. Further, RAGE effects in the different bone cells and whether these effects are cell-type specific is unknown. The objective of the current review is to describe the literature over RAGE signaling in skeletal biology as well as discuss the clinical potential of RAGE as a diagnostic and/or therapeutic target in bone disease. RECENT FINDINGS The role of RAGE and its ligands during skeletal homeostasis, tissue repair, and disease onset/progression is beginning to be uncovered. For example, detrimental effects of the RAGE ligands, advanced glycation end products (AGEs), have been identified for osteoblast viability/activity, while others have observed that low level AGE exposure stimulates osteoblast autophagy, which subsequently promotes viability and function. Similar findings have been reported with HMGB1, another RAGE ligand, in which high levels of the ligand are associated with osteoblast/osteocyte apoptosis, whereas low level/short-term administration stimulates osteoblast differentiation/bone formation and promotes fracture healing. Additionally, elevated levels of several RAGE ligands (AGEs, HMGB1, S100 proteins) induce osteoblast/osteocyte apoptosis and stimulate cytokine production, which is associated with increased osteoclast differentiation/activity. Conversely, direct RAGE-ligand exposure in osteoclasts may have inhibitory effects. These observations support a conclusion that elevated bone resorption observed in conditions of high circulating ligands and RAGE expression are due to actions on osteoblasts/osteocytes rather than direct actions on osteoclasts, although additional work is required to substantiate the observations. Recent studies have demonstrated that RAGE and its ligands play an important physiological role in the regulation of skeletal development, homeostasis, and repair/regeneration. Conversely, elevated levels of RAGE and its ligands are clearly related with various diseases associated with increased bone loss and fragility. However, despite the recent advancements in the field, many questions regarding RAGE and its ligands in skeletal biology remain unanswered.
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Affiliation(s)
- Lilian I Plotkin
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Dr., MS 5023, Indianapolis, IN, 46202, USA.
- Roudebush Veterans Administration Medical Center, Indianapolis, IN, USA.
- Indiana Center for Musculoskeletal Health, Indianapolis, IN, USA.
| | - Alyson L Essex
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Dr., MS 5023, Indianapolis, IN, 46202, USA
- Indiana Center for Musculoskeletal Health, Indianapolis, IN, USA
| | - Hannah M Davis
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Dr., MS 5023, Indianapolis, IN, 46202, USA
- Indiana Center for Musculoskeletal Health, Indianapolis, IN, USA
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21
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Zhang C, Wei W, Chi M, Wan Y, Li X, Qi M, Zhou Y. FOXO1 Mediates Advanced Glycation End Products Induced Mouse Osteocyte-Like MLO-Y4 Cell Apoptosis and Dysfunctions. J Diabetes Res 2019; 2019:6757428. [PMID: 31886284 PMCID: PMC6899319 DOI: 10.1155/2019/6757428] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 10/01/2019] [Accepted: 10/17/2019] [Indexed: 12/12/2022] Open
Abstract
Osteocyte plays an essential role in bone metabolism by regulating osteoblast and osteoclast activities. Dysfunction or apoptosis of osteocyte will severely endanger the bone homeostasis and result in bone diseases such as osteoporosis. Osteoporosis has been considered as one of the diabetes complications; however, the mechanism is still to be discovered. Advanced glycation end products (AGEs), as the main pathogenic factor of diabetes mellitus, have the capacity to induce osteocyte apoptosis thus sabotaging bone homeostasis. Here, we examined the role of AGE during osteocyte apoptosis and how this effect would affect osteocyte's regulation of osteoblast and osteoclast. Mouse osteocyte-like MLO-Y4 cells were used to study the properties of osteocyte and to examine its biological and pathological function. MTT assay and Annexin V assay showed that AGE significantly induce MLO-Y4 cell apoptosis. qPCR and Western blot results have shown that AGE upregulates proapoptotic gene p53 and its downstream target gene Bax, which leads to enhanced activation of caspase-3, thus inducing apoptosis in MLO-Y4 cells. Increased expression of sclerostin and RANKL in osteocytes has shown that AGE induces osteocyte dysfunction thus severely damaging the bone homeostasis by decreasing osteoblast and increasing osteoclast activities. Furthermore, the role of the transcription factor FOXO1, which is intensely associated with apoptosis, has been determined. Western blot has shown that AGE significantly decreases Akt activities. Immunofluorescence has shown that AGE promotes FOXO1 nuclei localization and enhances FOXO1 expression. Silencing of FOXO1 suppressed AGE-enhanced apoptosis; mRNA and protein expressions of cleaved caspase-3, sclerostin, and RANKL were downregulated as well. Moreover, exogenous FOXO1 increased caspase-3 mRNA levels and caspase-3 transcriptional activity. Lastly, ChIP assay has established the capacity of FOXO1 binding directly on the caspase-3, sclerostin, and RANKL promoter region in AGE environment, providing the mechanism of the AGE-induced osteocyte apoptosis and dysfunction. Our results have shown that FOXO1 plays a crucial role in AGE-induced osteocyte dysfunction and apoptosis through its regulation of caspase-3, sclerostin, and RANKL. This study provides new insight into diabetes-enhanced risk of osteoporosis given the critical role of AGE in the pathogenesis of diabetes and the essential part of osteocyte in bone metabolism.
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Affiliation(s)
- Citong Zhang
- Department of Oral Implantology, School and Hospital of Stomatology, Jilin University, Changchun, China
| | - Wei Wei
- Ministry of Health Key Laboratory of Radiobiology, Jilin University, Changchun, Jilin, China
| | - Minghan Chi
- Department of Oral Implantology, School and Hospital of Stomatology, Jilin University, Changchun, China
| | - Yao Wan
- Department of Oral Implantology, School and Hospital of Stomatology, Jilin University, Changchun, China
| | - Xue Li
- Department of Oral Implantology, School and Hospital of Stomatology, Jilin University, Changchun, China
| | - Manlin Qi
- Department of Oral Implantology, School and Hospital of Stomatology, Jilin University, Changchun, China
| | - Yanmin Zhou
- Department of Oral Implantology, School and Hospital of Stomatology, Jilin University, Changchun, China
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22
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Wang P, Tang C, Wu J, Yang Y, Yan Z, Liu X, Shao X, Zhai M, Gao J, Liang S, Luo E, Jing D. Pulsed electromagnetic fields regulate osteocyte apoptosis, RANKL/OPG expression, and its control of osteoclastogenesis depending on the presence of primary cilia. J Cell Physiol 2018; 234:10588-10601. [DOI: 10.1002/jcp.27734] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 10/18/2018] [Indexed: 12/23/2022]
Affiliation(s)
- Pan Wang
- Department of Biomedical Engineering Fourth Military Medical University Xi’an China
| | - Chi Tang
- Department of Biomedical Engineering Fourth Military Medical University Xi’an China
| | - Junjie Wu
- State Key Laboratory of Military Stomatology, Department of Orthodontics School of Stomatology, Fourth Military Medical University Xi’an China
| | - Yuefan Yang
- Department of Neurosurgery 251 Hospital of Chinese People’s Liberation Army Zhangjiakou China
| | - Zedong Yan
- Department of Biomedical Engineering Fourth Military Medical University Xi’an China
| | - Xiyu Liu
- Department of Biomedical Engineering Fourth Military Medical University Xi’an China
| | - Xi Shao
- Department of Biomedical Engineering Fourth Military Medical University Xi’an China
| | - Mingming Zhai
- Department of Biomedical Engineering Fourth Military Medical University Xi’an China
| | - Jie Gao
- State Key Laboratory of Military Stomatology, Department of Orthodontics School of Stomatology, Fourth Military Medical University Xi’an China
| | - Shengru Liang
- Department of Endocrinology Xijing Hospital, Fourth Military Medical Univerisity Xi’an China
| | - Erping Luo
- Department of Biomedical Engineering Fourth Military Medical University Xi’an China
| | - Da Jing
- Department of Biomedical Engineering Fourth Military Medical University Xi’an China
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23
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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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24
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Dirkes RK, Ortinau LC, Rector RS, Olver TD, Hinton PS. Insulin-Stimulated Bone Blood Flow and Bone Biomechanical Properties Are Compromised in Obese, Type 2 Diabetic OLETF Rats. JBMR Plus 2017; 1:116-126. [PMID: 30283885 PMCID: PMC6124191 DOI: 10.1002/jbm4.10007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 05/08/2017] [Accepted: 05/10/2017] [Indexed: 01/20/2023] Open
Abstract
Type 2 diabetes (T2D) increases skeletal fragility and fracture risk; however, the underlying mechanisms remain to be identified. Impaired bone vascular function, in particular insulin‐stimulated vasodilation and blood flow is a potential, yet unexplored mechanism. The purpose of this study was to determine the effects of T2D on femoral biomechanical properties, trabecular microarchitecture, and insulin‐stimulated bone vasodilation by comparison of hyperphagic Otsuka Long‐Evans Tokushima Fatty (OLETF) rats with normoglycemic control OLETF rats. Four‐week old, male OLETF rats were randomized to two groups: type 2 diabetes (O‐T2D) or normoglycemic control (O‐CON). O‐T2D were allowed ad libitum access to a rodent chow diet and O‐CON underwent moderate caloric restriction (30% restriction relative to intake of O‐T2D) to maintain normal body weight (BW) and glycemia until 40 weeks of age. Hyperphagic O‐T2D rats had significantly greater BW, body fat, and blood glucose than O‐CON. Total cross‐sectional area (Tt.Ar), cortical area (Ct.Ar), Ct.Ar/Tt.Ar, and polar moment of inertia of the mid‐diaphyseal femur adjusted for BW were greater in O‐T2D rats versus O‐CON. Whole‐bone biomechanical properties of the femur assessed by torsional loading to failure did not differ between O‐T2D and O‐CON, but tissue‐level strength and stiffness adjusted for BW were reduced in O‐T2D relative to O‐CON. Micro–computed tomography (μCT) of the distal epiphysis showed that O‐T2D rats had reduced percent bone volume, trabecular number, and connectivity density, and greater trabecular spacing compared with O‐CON. Basal tibial blood flow assessed by microsphere infusion was similar in O‐T2D and O‐CON, but the blood flow response to insulin stimulation in both the proximal epiphysis and diaphyseal marrow was lesser in O‐T2D compared to O‐CON. In summary, impaired insulin‐stimulated bone blood flow is associated with deleterious changes in bone trabecular microarchitecture and cortical biomechanical properties in T2D, suggesting that vascular dysfunction might play a causal role in diabetic bone fragility. © 2017 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.
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Affiliation(s)
- Rebecca K Dirkes
- Department of Nutrition and Exercise Physiology University of Missouri-Columbia Columbia MO USA
| | - Laura C Ortinau
- Department of Nutrition and Exercise Physiology University of Missouri-Columbia Columbia MO USA
| | - R Scott Rector
- Department of Nutrition and Exercise Physiology University of Missouri-Columbia Columbia MO USA.,Division of Gastroenterology and Hepatology Department of Medicine University of Missouri-Columbia Columbia MO USA.,Research Service Harry S Truman Memorial VA Hospital Columbia MO USA
| | - T Dylan Olver
- Department of Biomedical Sciences University of Missouri-Columbia Columbia MO USA
| | - Pamela S Hinton
- Department of Nutrition and Exercise Physiology University of Missouri-Columbia Columbia MO USA
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