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Yee CS, Meliadis C, Kaya S, Chang W, Alliston T. The osteocytic actions of glucocorticoids on bone mass, mechanical properties, or perilacunar remodeling outcomes are not rescued by PTH(1-34). Front Endocrinol (Lausanne) 2024; 15:1342938. [PMID: 39092287 PMCID: PMC11291448 DOI: 10.3389/fendo.2024.1342938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 06/26/2024] [Indexed: 08/04/2024] Open
Abstract
Glucocorticoids (GC) and parathyroid hormone (PTH) are widely used therapeutic endocrine hormones where their effects on bone and joint arise from actions on multiple skeletal cell types. In osteocytes, GC and PTH exert opposing effects on perilacunar canalicular remodeling (PLR). Suppressed PLR can impair bone quality and joint homeostasis, including in GC-induced osteonecrosis. However, combined effects of GC and PTH on PLR are unknown. Given the untapped potential to target osteocytes to improve skeletal health, this study sought to test the feasibility of therapeutically mitigating PLR suppression. Focusing on subchondral bone and joint homeostasis, we hypothesize that PTH(1-34), a PLR agonist, could rescue GC-suppressed PLR. The skeletal effects of GC and PTH(1-34), alone or combined, were examined in male and female mice by micro-computed tomography, mechanical testing, histology, and gene expression analysis. For each outcome, females were more responsive to GC and PTH(1-34) than males. GC and PTH(1-34) exerted regional differences, with GC increasing trabecular bone volume but reducing cortical bone thickness, stiffness, and ultimate force. Despite PTH(1-34)'s anabolic effects on trabecular bone, it did not rescue GC's catabolic effects on cortical bone. Likewise, cartilage integrity and subchondral bone apoptosis, tartrate-resistant acid phosphatase (TRAP) activity, and osteocyte lacunocanalicular networks showed no evidence that PTH(1-34) could offset GC-dependent effects. Rather, GC and PTH(1-34) each increased cortical bone gene expression implicated in bone resorption by osteoclasts and osteocytes, including Acp5, Mmp13, Atp6v0d2, Ctsk, differences maintained when GC and PTH(1-34) were combined. Since PTH(1-34) is insufficient to rescue GC's effects on young female mouse bone, future studies are needed to determine if osteocyte PLR suppression, due to GC, aging, or other factors, can be offset by a PLR agonist.
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Affiliation(s)
- Cristal S. Yee
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Christoforos Meliadis
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Serra Kaya
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, United States
| | - Wenhan Chang
- Endocrine Research Unit, San Francisco Veterans Affairs Medical Center, University of California, San Francisco, CA, United States
| | - Tamara Alliston
- Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA, United States
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2
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Mazur CM, Castro Andrade CD, Tokavanich N, Sato T, Bruce M, Brooks DJ, Bouxsein ML, Wang JS, Wein MN. Partial prevention of glucocorticoid-induced osteocyte deterioration in young male mice with osteocrin gene therapy. iScience 2022; 25:105019. [PMID: 36105586 PMCID: PMC9464962 DOI: 10.1016/j.isci.2022.105019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Revised: 07/05/2022] [Accepted: 08/19/2022] [Indexed: 11/29/2022] Open
Abstract
Glucocorticoid excess suppresses osteocyte remodeling of surrounding bone minerals, causes apoptosis of osteoblasts and osteocytes, and disrupts bone remodeling, eventually, leading to glucocorticoid-induced osteoporosis and bone fragility. Preventing apoptosis and preserving osteocyte morphology could be an effective means of preventing bone loss during glucocorticoid treatment. We hypothesized that osteocrin, which preserves osteocyte viability and morphology in Sp7-deficient mice, could prevent osteocyte death and dysfunction in a glucocorticoid excess model. We used adeno-associated virus (AAV8) to induce osteocrin overexpression in mice one week before implantation with prednisolone or placebo pellets. After 28 days, prednisolone caused the expected reduction in cortical bone thickness and osteocyte canalicular length in control AAV8-treated mice, and these effects were blunted in mice receiving AAV8-osteocrin. Glucocorticoid-induced changes in cortical porosity, trabecular bone mass, and gene expression were not prevented by osteocrin. These findings support a modest therapeutic potential for AAV8-osteocrin in preserving osteocyte morphology during disease.
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Affiliation(s)
- Courtney M. Mazur
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Nicha Tokavanich
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Tadatoshi Sato
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Michael Bruce
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Daniel J. Brooks
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Center for Advanced Orthopedic Studies, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Mary L. Bouxsein
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Center for Advanced Orthopedic Studies, Department of Orthopedic Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Jialiang S. Wang
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Marc N. Wein
- Endocrine Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Harvard Stem Cell Institute, Cambridge, MA, USA
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Jiang M, Liu L, Xiang X, Liang R, Qin X, Zhao J, Wei Q. An MSC bone-homing compound, Rab001, increases bone mass and reduces the incidence of osteonecrosis in a glucocorticoid-induced osteonecrosis mouse model. Clin Exp Pharmacol Physiol 2021; 48:770-781. [PMID: 33319413 DOI: 10.1111/1440-1681.13441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/18/2020] [Indexed: 11/30/2022]
Abstract
Currently, there are no effective medications to either prevent or slow the progression of atraumatic osteonecrosis (ON). The objective of this study is to determine the effects of bone-targeted delivery of mesenchymal stem cells on the prevalence of ON in a glucocorticoid (GC)-induced mouse model. Eight-week-old male BALB/c mice were randomized into groups that received placebo (PL), prednisolone (GC), or concurrent treatments with GC + mesenchymal stromal cells (MSCs), Rab001 or GC + Rab001 + MSCs. Human parathyroid hormone (hPTH) was used as a positive control for bone anabolism. Mice were killed after 30 days, and quantitative measurements of bone mass, bone strength, prevalent ON at the distal femoral epiphysis (DFE) were performed. Angiogenesis was accessed by RNA-Seq, the circulating angiogenic markers, as well as by immunohistochemical staining. We have showed that a novel agent, Rab001 that can noncovalently bind to mesenchymal stem cells (MSC) and direct them to the bone, prevents the incidence of glucocorticoid-induced osteonecrosis in the mouse. In contrast, PTH, a bone anabolic treatment, preserves bone mass but sustains higher ON incidence than Rab001+/- MSC-treated mice. The results of these experiments reveal that glucocorticoids increase the prevalence of ON, and agents that prevent loss of bone vascularity appear to prevent the development of ON. This intervention might be useful in patients with early stages of atraumatic ON.
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Affiliation(s)
- Min Jiang
- Guangxi Laide Kangshun Bio-pharmaceutical Technology Co., Ltd., Nanning, China
- Shanghai Key Laboratory for Bone and Joint Diseases, Shanghai Institute of Traumatology and Orthopaedics, Shanghai Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Lixian Liu
- Yunnan Vocational and Technical College of Agriculture, Kunming, China
| | - Xuexiang Xiang
- Guangxi Laide Kangshun Bio-pharmaceutical Technology Co., Ltd., Nanning, China
| | - Runmin Liang
- Guangxi Laide Kangshun Bio-pharmaceutical Technology Co., Ltd., Nanning, China
| | - Xuelian Qin
- Guangxi Laide Kangshun Bio-pharmaceutical Technology Co., Ltd., Nanning, China
| | - Jinmin Zhao
- Department of Orthopaedics Trauma and Hand Surgery, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, China
- Guangxi Engineering Center in Biomedical Materials for Tissue and Organ Regeneration, Guangxi Medical University, Nanning, China
- Guangxi Key Laboratory of Regenerative Medicine, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, China
| | - Qingjun Wei
- Department of Orthopaedics Trauma and Hand Surgery, The First Affiliated Hospital of Guangxi Medical University, Guangxi Medical University, Nanning, China
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Dubrovsky AM, Nyman JS, Uppuganti S, Chmiel KJ, Kimmel DB, Lane NE. Bone Strength/Bone Mass Discrepancy in Glucocorticoid-Treated Adult Mice. JBMR Plus 2020; 5:e10443. [PMID: 33778319 PMCID: PMC7990143 DOI: 10.1002/jbm4.10443] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 11/16/2020] [Accepted: 11/22/2020] [Indexed: 11/12/2022] Open
Abstract
Glucocorticoids increase bone fragility in patients in a manner that is underestimated by bone mass measurement. This study aimed to determine if the adult mouse could model this bone strength/bone mass discrepancy. Forty‐two 13‐week‐old BALB/cJ mice were randomized into vehicle and glucocorticoid groups, implanted with vehicle or 6‐methylprednisolone pellets, and necropsied after 60 and 120 days. Bone strength and bone mass/microarchitecture were assessed at the right central femur (CF; cortical‐bone–rich) and sixth lumbar vertebral body (LVB6; trabecular‐bone–rich). Bound water (BW) of the whole right femur was analyzed by proton‐nuclear magnetic resonance (1H‐NMR) relaxometry. Data were analyzed by two‐factor ANOVA with time (day 60 and day 120) and treatment (vehicle and glucocorticoid) as main effects for all data. Significant interactions were further analyzed with a Tukey's post hoc test. Most bone strength measures in the CF were lower in the glucocorticoid group, regardless of the duration of treatment, with no time × treatment interaction. However, bone mass measures in the CF showed a significant time × treatment interaction (p = 0.0001). Bone strength measures in LVB6 showed a time × treatment interaction (p < 0.02) such that LVB6 strength was lower after 120 days of glucocorticoids compared with 120 days of vehicle treatment. Whole‐femur–BW was lower with both glucocorticoid treatment (p = 0.0001) and time (p < 0.02), with a significant time × treatment interaction (p = 0.005). Glucocorticoid treatment of male BALB/cJ mice resulted in the lowering of bone strength in both cortical and trabecular bone that either appeared earlier or was greater than the treatment‐related changes in bone mass/microarchitecture. The adult mouse may be a good model for investigating the bone strength/mass discrepancy observed in glucocorticoid‐treated patients. © 2020 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)
- Alanna M Dubrovsky
- Center for Musculoskeletal Health University of California at Davis Medical Center Sacramento CA USA
| | - Jeffrey S Nyman
- Department of Orthopaedic Surgery Vanderbilt University Medical Center Nashville TN USA
| | - Sasidhar Uppuganti
- Department of Orthopaedic Surgery Vanderbilt University Medical Center Nashville TN USA
| | - Kenneth J Chmiel
- Center for Musculoskeletal Health University of California at Davis Medical Center Sacramento CA USA
| | - Donald B Kimmel
- Department of Physiological Sciences University of Florida Gainesville FL USA
| | - Nancy E Lane
- Center for Musculoskeletal Health University of California at Davis Medical Center Sacramento CA USA
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5
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van Elsas M, Kleinovink JW, Moerland M, Feiss G, Beyrend G, Arens R, Mei H, Nibbering PH, Jirka SM, van Hall T, van der Burg SH. Host genetics and tumor environment determine the functional impact of neutrophils in mouse tumor models. J Immunother Cancer 2020; 8:jitc-2020-000877. [PMID: 32998952 PMCID: PMC7528431 DOI: 10.1136/jitc-2020-000877] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/27/2020] [Indexed: 01/06/2023] Open
Abstract
Background Neutrophils have been reported to have protumor, antitumor or neutral effects in cancer progression. The underlying causes for this functional variability are not clear. Methods We studied the role of neutrophils in six different mouse tumor models by intratumoral injection of antimicrobial peptides or vaccination. Changes in systemic and intratumoral immune cells were analyzed by flow-cytometry and mass-cytometry. The role of neutrophils was studied by antibody-mediated neutrophil depletion. Neutrophils from different mouse strains were compared by RNA sequencing. Results The antimicrobial peptide Omiganan reduced the growth of TC-1 tumors in BL/6 mice and CT26 tumors in BALB/c mice. No significant effects were observed in B16F10, MC38 and 4T1 tumors. Growth delay was associated with increased abundance of neutrophils in TC-1 but not CT26 tumors. Systemic neutrophil depletion abrogated Omiganan efficacy in TC-1 but further reduced growth of CT26, indicating that neutrophils were required for the antitumor effect in TC-1 but suppressed tumor control in CT26. Neutrophils were also required for a therapeutic vaccine-induced T-cell mediated control of RMA tumors in BL/6 mice. Clearly, the circulating and intratumoral neutrophils differed in the expression of Ly6G and CD62L, between TC-1 and CT26 and between blood neutrophils of tumor-naïve BL/6 and BALB/c mice. RNA-sequencing revealed that neutrophils from BL/6 mice but not BALB/c mice displayed a robust profile of immune activation, matching their opposing roles in TC-1 and RMA versus CT26. Conclusions Neutrophil functionality differs strongly between mouse strains and tumor types, with consequences for tumor progression and therapy.
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Affiliation(s)
- Marit van Elsas
- Medical Oncology, Oncode institute, Leiden University Medical Center, Leiden, The Netherlands
| | - Jan Willem Kleinovink
- Medical Oncology, Oncode institute, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Gary Feiss
- Cutanea Life Sciences, Wayne, Pennsylvania, USA
| | - Guillaume Beyrend
- Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands
| | - Ramon Arens
- Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands
| | - Hailiang Mei
- Sequencing Analysis Support Core, Leiden University Medical Center, Leiden, The Netherlands
| | - Peter H Nibbering
- Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands
| | | | - Thorbald van Hall
- Medical Oncology, Oncode institute, Leiden University Medical Center, Leiden, The Netherlands
| | - Sjoerd H van der Burg
- Medical Oncology, Oncode institute, Leiden University Medical Center, Leiden, The Netherlands
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6
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Chen K, Liu Y, He J, Pavlos N, Wang C, Kenny J, Yuan J, Zhang Q, Xu J, He W. Steroid-induced osteonecrosis of the femoral head reveals enhanced reactive oxygen species and hyperactive osteoclasts. Int J Biol Sci 2020; 16:1888-1900. [PMID: 32398957 PMCID: PMC7211180 DOI: 10.7150/ijbs.40917] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Accepted: 03/18/2020] [Indexed: 12/16/2022] Open
Abstract
Steroid-induced osteonecrosis of the femoral head (ONFH) is a progressive bone disorder which typically results in femoral head collapse and hip joint dysfunction. It is well-accepted that abnormal osteoclast activity contributes to loss of bone structural integrity and subchondral fracture in ONFH. However, the pathophysiologic mechanisms underlying the recruitment and hyperactivation of osteoclasts in ONFH remain incompletely understood. We assessed the changes of reactive oxygen species (ROS) level and subsequent osteoclast alterations in steroid-induced osteonecrotic femoral heads from both patients and rat ONFH models. When compared with healthy neighboring bone, the necrotic region of human femoral head was characterized by robust up-regulated expression of osteoclast-related proteins [cathepsin K and tartrate-resistant acid phosphatase(TRAP)] but pronounced down-regulation of antioxidant enzymes (catalase, γ-glutamylcysteine synthetase [γ-GCSc], and superoxide dismutase 1 [SOD1]). In addition, the ratio of TNFSF11 (encoding RANKL)/TNFRSF11B (encoding OPG) was increased within the necrotic bone. Consistently, in rat ONFH models induced by methylprednisolone (MPSL) and imiquimod (IMI), significant bone loss in the femoral head was observed, attributable to increased numbers of TRAP positive osteoclasts. Furthermore, the decreased expression of antioxidant enzymes observed by immunoblotting was accompanied by increased ex-vivo ROS fluorescence signals of dihydroethidium (DHE) in rat ONFH models. Therefore, this study lends support to the rationale that antioxidant agents may be a promising therapeutic avenue to prevent or mitigate the progression of steroid-induced ONFH by inhibiting ROS level and hyperactive osteoclasts.
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Affiliation(s)
- Kai Chen
- School of Biomedical Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Yuhao Liu
- School of Biomedical Sciences, The University of Western Australia, Perth, WA 6009, Australia.,Department of Joint Orthopaedics, The First Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, China.,The Lab of Orthopaedics of Chinese Medicine, Lingnan Medical Research Center, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, China
| | - Jianbo He
- School of Biomedical Sciences, The University of Western Australia, Perth, WA 6009, Australia.,The Lab of Orthopaedics of Chinese Medicine, Lingnan Medical Research Center, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, China
| | - Nathan Pavlos
- School of Biomedical Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Chao Wang
- School of Biomedical Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Jacob Kenny
- School of Biomedical Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Jinbo Yuan
- School of Biomedical Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Qingwen Zhang
- Department of Joint Orthopaedics, The First Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, China.,The Lab of Orthopaedics of Chinese Medicine, Lingnan Medical Research Center, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, China
| | - Jiake Xu
- School of Biomedical Sciences, The University of Western Australia, Perth, WA 6009, Australia.,Department of Joint Orthopaedics, The First Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, China
| | - Wei He
- Department of Joint Orthopaedics, The First Affiliated Hospital, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, China.,The Lab of Orthopaedics of Chinese Medicine, Lingnan Medical Research Center, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, China.,Research Institute of Orthopaedics of Chinese Medicine, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510378, China
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7
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Alamu O, Rado M, Ekpo O, Fisher D. Differential Sensitivity of Two Endothelial Cell Lines to Hydrogen Peroxide Toxicity: Relevance for In Vitro Studies of the Blood-Brain Barrier. Cells 2020; 9:cells9020403. [PMID: 32050666 PMCID: PMC7072657 DOI: 10.3390/cells9020403] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 12/20/2019] [Accepted: 01/06/2020] [Indexed: 12/19/2022] Open
Abstract
Oxidative stress (OS) has been linked to blood–brain barrier (BBB) dysfunction which in turn has been implicated in the initiation and propagation of some neurological diseases. In this study, we profiled, for the first time, two endothelioma cell lines of mouse brain origin, commonly used as in vitro models of the blood–brain barrier, for their resistance against oxidative stress using viability measures and glutathione contents as markers. OS was induced by exposing cultured cells to varying concentrations of hydrogen peroxide and fluorescence microscopy/spectrometry was used to detect and estimate cellular glutathione contents. A colorimetric viability assay was used to determine changes in the viability of OS-exposed cells. Both the b.End5 and bEnd.3 cell lines investigated showed demonstrable content of glutathione with a statistically insignificant difference in glutathione quantity per unit cell, but with a statistically significant higher capacity for the b.End5 cell line for de novo glutathione synthesis. Furthermore, the b.End5 cells demonstrated greater oxidant buffering capacity to higher concentrations of hydrogen peroxide than the bEnd.3 cells. We concluded that mouse brain endothelial cells, derived from different types of cell lines, differ enormously in their antioxidant characteristics. We hereby recommend caution in making comparisons across BBB models utilizing distinctly different cell lines and require further prerequisites to ensure that in vitro BBB models involving these cell lines are reliable and reproducible.
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Affiliation(s)
- Olufemi Alamu
- Department of Medical Bioscience, University of the Western Cape, Bellville, Cape Town 7530, South Africa; (O.A.); (M.R.); (O.E.)
- Anatomy Department, Ladoke Akintola University of Technology, Ogbomoso 210241, Nigeria
| | - Mariam Rado
- Department of Medical Bioscience, University of the Western Cape, Bellville, Cape Town 7530, South Africa; (O.A.); (M.R.); (O.E.)
| | - Okobi Ekpo
- Department of Medical Bioscience, University of the Western Cape, Bellville, Cape Town 7530, South Africa; (O.A.); (M.R.); (O.E.)
| | - David Fisher
- Department of Medical Bioscience, University of the Western Cape, Bellville, Cape Town 7530, South Africa; (O.A.); (M.R.); (O.E.)
- Correspondence: ; Tel.: +27-21-959-2185
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8
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Yang J, Li J, Cui X, Li W, Xue Y, Shang P, Zhang H. Blocking glucocorticoid signaling in osteoblasts and osteocytes prevents mechanical unloading-induced cortical bone loss. Bone 2020; 130:115108. [PMID: 31704341 DOI: 10.1016/j.bone.2019.115108] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 09/25/2019] [Accepted: 10/10/2019] [Indexed: 12/13/2022]
Abstract
Bone loss has been supposed to be the greatest damage to the health of astronauts. It is generally believed that the mechanical unloading induced by microgravity is the main cause of bone loss. However, besides mechanical unloading, many evidences from animal models and spaceflight missions indicate that microgravity conditions can cause some stress reactions and elevated endogenous glucocorticoid (GC) levels. High levels of GCs can lead to bone loss. This study aimed to investigate whether elevated GC levels are involved in hindlimb unloading (HLU)-induced bone loss in mice. Col2.3-11β-hydroxysteroid dehydrogenase type 2 (Col2.3-11β-HSD2) transgenic mice which are characterized by specific blocking GC signaling in mature osteoblasts and osteocytes were used. Male 14-week-old Col2.3-11β-HSD2 transgenic mice and wild type littermates were tail-suspended or kept under ambulatory conditions. At the endpoint, the tibias were examined by micro-computed tomography and histomorphometry, and bone turnover was analyzed by serum biochemistry, histochemistry staining, immunohistochemistry, and real-time PCR. Mice exposed to unloading occurred a significant increase in serum GC concentrations. Compared with non-unloaded controls, HLU led to a severe damage in cortical bone microstructure and bone strength of the tibia in wild type mice but not transgenic littermates. Osteoblast activity and bone formation were inhibited, whereas osteoclast activity and bone resorption were promoted in the tibial cortical bone of wild type mice following HLU, features absented in transgenic mice. Furthermore, HLU resulted in a significant increase in the number of sclerostin-producing and receptor activator of nuclear factor-κ B ligand (RANKL)-positive osteocytes, and apoptotic osteoblasts and osteocytes in wild type mice of unloading but not in unloaded transgenic mice. In conclusion, cortical bone loss during HLU is mediated through enhancing GC signaling in osteoblasts and osteocytes and subsequently restraining bone formation and activating bone resorption. It suggests that elevated GC levels play an important role in cortical bone loss in response to mechanical unloading.
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Affiliation(s)
- Jiancheng Yang
- Department of Spinal Surgery, People's Hospital of Longhua Shenzhen, Shenzhen, China; School of Life Sciences, Northwestern Polytechnical University, Xi'an, China; Key Laboratory for Space Bioscience and Biotechnology, Northwestern Polytechnical University, Xi'an, China
| | - Jingbao Li
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China; Key Laboratory for Space Bioscience and Biotechnology, Northwestern Polytechnical University, Xi'an, China
| | - Xiaobin Cui
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China; Key Laboratory for Space Bioscience and Biotechnology, Northwestern Polytechnical University, Xi'an, China
| | - Wenbin Li
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China; Key Laboratory for Space Bioscience and Biotechnology, Northwestern Polytechnical University, Xi'an, China
| | - Yanru Xue
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China; Key Laboratory for Space Bioscience and Biotechnology, Northwestern Polytechnical University, Xi'an, China
| | - Peng Shang
- School of Life Sciences, Northwestern Polytechnical University, Xi'an, China; Research & Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen, China; Key Laboratory for Space Bioscience and Biotechnology, Northwestern Polytechnical University, Xi'an, China.
| | - Hao Zhang
- Department of Spinal Surgery, People's Hospital of Longhua Shenzhen, Shenzhen, China.
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