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Swarnkar G, Semenkovich NP, Arra M, Mims DK, Naqvi SK, Peterson T, Mbalaviele G, Wu CL, Abu-Amer Y. DNA hypomethylation ameliorates erosive inflammatory arthritis by modulating interferon regulatory factor-8. Proc Natl Acad Sci U S A 2024; 121:e2310264121. [PMID: 38319963 PMCID: PMC10873594 DOI: 10.1073/pnas.2310264121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 01/08/2024] [Indexed: 02/08/2024] Open
Abstract
Epigenetic regulation plays a crucial role in the pathogenesis of autoimmune diseases such as inflammatory arthritis. DNA hypomethylating agents, such as decitabine (DAC), have been shown to dampen inflammation and restore immune homeostasis. In the present study, we demonstrate that DAC elicits potent anti-inflammatory effects and attenuates disease symptoms in several animal models of arthritis. Transcriptomic and epigenomic profiling show that DAC-mediated hypomethylation regulates a wide range of cell types in arthritis, altering the differentiation trajectories of anti-inflammatory macrophage populations, regulatory T cells, and tissue-protective synovial fibroblasts (SFs). Mechanistically, DAC-mediated demethylation of intragenic 5'-Cytosine phosphate Guanine-3' (CpG) islands of the transcription factor Irf8 (interferon regulatory factor 8) induced its re-expression and promoted its repressor activity. As a result, DAC restored joint homeostasis by resetting the transcriptomic signature of negative regulators of inflammation in synovial macrophages (MerTK, Trem2, and Cx3cr1), TREGs (Foxp3), and SFs (Pdpn and Fapα). In conclusion, we found that Irf8 is necessary for the inhibitory effect of DAC in murine arthritis and that direct expression of Irf8 is sufficient to significantly mitigate arthritis.
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Affiliation(s)
- Gaurav Swarnkar
- Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, MO63110
| | | | - Manoj Arra
- Department of Emergency Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Dorothy K. Mims
- Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, MO63110
| | - Syeda Kanwal Naqvi
- Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, MO63110
| | - Timothy Peterson
- Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
- HealthSpan Technologies, Inc, St. Louis, MO63110
| | - Gabriel Mbalaviele
- Department of Medicine, Washington University School of Medicine, St. Louis, MO63110
| | - Chia-Lung Wu
- Department of Orthopedics and Physical Performance, University of Rochester, Rochester, NY14642
| | - Yousef Abu-Amer
- Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, MO63110
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO63110
- Shriners Hospital for Children, St. Louis, MO63110
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2
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Lee S, Kim MJ, Ahn SI, Choi SK, Min KY, Choi WS, You JS. Epigenetic landscape analysis reveals the significance of early reduced chromatin accessibility in osteoclastogenesis. Bone 2023; 177:116918. [PMID: 37739296 DOI: 10.1016/j.bone.2023.116918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/24/2023]
Abstract
Recently improved techniques could provide snapshots of chromatin structure generated based on chromatin accessibility. Since chromatin accessibility determines transcriptional potential, it has been attempted in a variety of cell systems. However, there has been no genome-wide analysis of chromatin accessibility for the entire murine osteoclast (OC) differentiation process. We performed an Assay for Transposase-Accessible Chromatin (ATAC)-sequencing (seq) during RANKL-induced OC differentiation and found that global chromatin accessibility decreased, especially early in OC differentiation. The global histone H3K27Ac level, an active histone modification mark, was diminished during OC differentiation by western blot and histone extract experiments. Its genomic enrichment was also reduced based on publicly available H3K27Ac chromatin immunoprecipitation (ChIP)-seq data. ATAC-seq and H3K27Ac ChIP-seq data demonstrated that RANKL induced a less accessible chromatin state during OC differentiation. Restoration of reduced H3K27Ac, presumably representing accessible states upon acetate treatment, suppresses OC differentiation by provoking immune-related gene expression. Subsequential integrative analysis of ATAC-seq, RNA-seq after acetate treatment, and H3K27Ac ChIP-seq reveals that Irf8 and its downstream targets are the most vulnerable to chromatin accessibility changes and acetate supplementation. Taken together, our study generated chromatin accessibility maps during the whole OC differentiation and suggested perturbation of chromatin accessibility might be a potential therapeutic strategy for excessive OC diseases.
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Affiliation(s)
- Sangyong Lee
- School of Medicine, Konkuk University, Chungju 27478, Republic of Korea
| | - Myoung Jun Kim
- School of Medicine, Konkuk University, Chungju 27478, Republic of Korea
| | - Seor I Ahn
- School of Medicine, Konkuk University, Chungju 27478, Republic of Korea
| | - Sung Kyung Choi
- School of Medicine, Konkuk University, Chungju 27478, Republic of Korea
| | - Keun Young Min
- School of Medicine, Konkuk University, Chungju 27478, Republic of Korea
| | - Wahn Soo Choi
- School of Medicine, Konkuk University, Chungju 27478, Republic of Korea; KU Open Innovation Center, Research Institute of Medical Science, Konkuk University, Republic of Korea
| | - Jueng Soo You
- School of Medicine, Konkuk University, Chungju 27478, Republic of Korea; KU Open Innovation Center, Research Institute of Medical Science, Konkuk University, Republic of Korea.
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3
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Swartz AM, Nair SK. The In Vitro Differentiation of Human CD141+CLEC9A+ Dendritic Cells from Mobilized Peripheral Blood CD34+ Hematopoietic Stem Cells. Curr Protoc 2022; 2:e410. [PMID: 35435334 DOI: 10.1002/cpz1.410] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
As shown in various preclinical studies, conventional type-1 dendritic cells, or cDC1s, play a critical role in the immunological rejection of tumors and in the defense against pathogens. This indispensability stems from their potent capacity to activate cytotoxic T cells, especially via the cross-presentation of exogenous antigens. For this reason, cDC1s have become an attractive target for immunotherapy. Here we report a simplified method for generating large numbers of cDC1-like cells in vitro from mobilized human peripheral blood CD34+ hematopoietic stem cells using FMS-like tyrosine kinase 3 ligand (FLT3L) and granulocyte-macrophage colony-stimulating factor (GM-CSF). An important aspect of this Protocol is the growth of cells on a non-tissue culture-treated surface rather than on a tissue culture-treated surface since the latter suppresses cDC1-marker expression. The resulting CD11c+ DCs express high levels of cDC1-specific markers such as CD141, CLEC9A, TLR3, and several DC maturation markers. Compared to alternative differentiation methods, this method generates large numbers of cDC1-like cells without the need for immortalized feeder cells and should prove useful for studying cDC1 immunobiology and clinical applications of this DC subset. © 2022 Wiley Periodicals LLC. Basic Protocol: Generation of human CD141+CLEC9A+ dendritic cells from mobilized peripheral blood CD34+ hematopoietic stem cells Support Protocol: Flow cytometric immunophenotyping of CD141+ dendritic cells.
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Affiliation(s)
- Adam M Swartz
- Department of Surgery, Duke University, Durham, North Carolina
| | - Smita K Nair
- Department of Surgery, Department of Neurosurgery, Department of Pathology, Duke University, Durham, North Carolina
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4
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Zhang P, Schlecht A, Wolf J, Boneva S, Laich Y, Koch J, Ludwig F, Boeck M, Thien A, Härdtner C, Kierdorf K, Agostini H, Schlunck G, Prinz M, Hilgendorf I, Wieghofer P, Lange C. The role of interferon regulatory factor 8 for retinal tissue homeostasis and development of choroidal neovascularisation. J Neuroinflammation 2021; 18:215. [PMID: 34544421 PMCID: PMC8454118 DOI: 10.1186/s12974-021-02230-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 08/04/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Microglia cells represent the resident innate immune cells of the retina and are important for retinal development and tissue homeostasis. However, dysfunctional microglia can have a negative impact on the structural and functional integrity of the retina under native and pathological conditions. METHODS In this study, we examined interferon-regulatory factor 8 (Irf8)-deficient mice to determine the transcriptional profile, morphology, and temporospatial distribution of microglia lacking Irf8 and to explore the effects on retinal development, tissue homeostasis, and formation of choroidal neovascularisation (CNV). RESULTS Our study shows that Irf8-deficient MG exhibit a considerable loss of microglial signature genes accompanied by a severely altered MG morphology. An in-depth characterisation by fundus photography, fluorescein angiography, optical coherence tomography and electroretinography revealed no major retinal abnormalities during steady state. However, in the laser-induced CNV model, Irf8-deficient microglia showed an increased activity of biological processes critical for inflammation and cell adhesion and a reduced MG cell density near the lesions, which was associated with significantly increased CNV lesion size. CONCLUSIONS Our results suggest that loss of Irf8 in microglia has negligible effects on retinal homeostasis in the steady state. However, under pathological conditions, Irf8 is crucial for the transformation of resident microglia into a reactive phenotype and thus for the suppression of retinal inflammation and CNV formation.
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Affiliation(s)
- Peipei Zhang
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Anja Schlecht
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany.,Institute of Anatomy, Wuerzburg University, Wuerzburg, Germany
| | - Julian Wolf
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Stefaniya Boneva
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Yannik Laich
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Jana Koch
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Franziska Ludwig
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Myriam Boeck
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Adrian Thien
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Carmen Härdtner
- Cardiology and Angiology, University Heart Center, University of Freiburg, Freiburg im Breisgau, Germany.,Medical Center and Faculty of Medicine, Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg Bad Krozingen, University of Freiburg, Freiburg, Germany
| | - Katrin Kierdorf
- Medical Faculty, Institute of Neuropathology, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany.,CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany.,Medical Faculty, Center for Basics in NeuroModulation (NeuroModulBasics), University of Freiburg, Freiburg im Breisgau, Germany
| | - Hansjürgen Agostini
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Günther Schlunck
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany
| | - Marco Prinz
- Medical Faculty, Institute of Neuropathology, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany.,Medical Faculty, Center for Basics in NeuroModulation (NeuroModulBasics), University of Freiburg, Freiburg im Breisgau, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg im Breisgau, Germany
| | - Ingo Hilgendorf
- Cardiology and Angiology, University Heart Center, University of Freiburg, Freiburg im Breisgau, Germany.,Medical Center and Faculty of Medicine, Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg Bad Krozingen, University of Freiburg, Freiburg, Germany
| | - Peter Wieghofer
- Medical Faculty, Institute of Neuropathology, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany. .,Institute of Anatomy, Leipzig University, Leipzig, Germany.
| | - Clemens Lange
- Medical Faculty, Eye Center, University Hospital, University of Freiburg, Freiburg im Breisgau, Germany.
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5
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Jassinskaja M, Pimková K, Arh N, Johansson E, Davoudi M, Pereira CF, Sitnicka E, Hansson J. Ontogenic shifts in cellular fate are linked to proteotype changes in lineage-biased hematopoietic progenitor cells. Cell Rep 2021; 34:108894. [PMID: 33761361 DOI: 10.1016/j.celrep.2021.108894] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 12/16/2020] [Accepted: 03/02/2021] [Indexed: 12/16/2022] Open
Abstract
The process of hematopoiesis is subject to substantial ontogenic remodeling that is accompanied by alterations in cellular fate during both development and disease. We combine state-of-the-art mass spectrometry with extensive functional assays to gain insight into ontogeny-specific proteomic mechanisms regulating hematopoiesis. Through deep coverage of the cellular proteome of fetal and adult lympho-myeloid multipotent progenitors (LMPPs), common lymphoid progenitors (CLPs), and granulocyte-monocyte progenitors (GMPs), we establish that features traditionally attributed to adult hematopoiesis are conserved across lymphoid and myeloid lineages, whereas generic fetal features are suppressed in GMPs. We reveal molecular and functional evidence for a diminished granulocyte differentiation capacity in fetal LMPPs and GMPs relative to their adult counterparts. Our data indicate an ontogeny-specific requirement of myosin activity for myelopoiesis in LMPPs. Finally, we uncover an ontogenic shift in the monocytic differentiation capacity of GMPs, partially driven by a differential expression of Irf8 during fetal and adult life.
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Affiliation(s)
- Maria Jassinskaja
- Lund Stem Cell Center, Division of Molecular Hematology, Lund University, 221 84 Lund, Sweden
| | - Kristýna Pimková
- Lund Stem Cell Center, Division of Molecular Hematology, Lund University, 221 84 Lund, Sweden
| | - Nejc Arh
- Lund Stem Cell Center, Division of Molecular Medicine and Gene Therapy, Lund University, 221 84 Lund, Sweden; Wallenberg Centre for Molecular Medicine, Lund University, 221 84 Lund, Sweden
| | - Emil Johansson
- Lund Stem Cell Center, Division of Molecular Hematology, Lund University, 221 84 Lund, Sweden; Department of Laboratory Medicine, Lund University, 221 84 Lund, Sweden
| | - Mina Davoudi
- Lund Stem Cell Center, Division of Molecular Hematology, Lund University, 221 84 Lund, Sweden
| | - Carlos-Filipe Pereira
- Lund Stem Cell Center, Division of Molecular Medicine and Gene Therapy, Lund University, 221 84 Lund, Sweden; Wallenberg Centre for Molecular Medicine, Lund University, 221 84 Lund, Sweden
| | - Ewa Sitnicka
- Lund Stem Cell Center, Division of Molecular Hematology, Lund University, 221 84 Lund, Sweden
| | - Jenny Hansson
- Lund Stem Cell Center, Division of Molecular Hematology, Lund University, 221 84 Lund, Sweden.
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6
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Bosteels C, Scott CL. Transcriptional regulation of DC fate specification. Mol Immunol 2020; 121:38-46. [PMID: 32151907 DOI: 10.1016/j.molimm.2020.02.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 02/26/2020] [Accepted: 02/28/2020] [Indexed: 12/12/2022]
Abstract
Dendritic cells function in the immune system to instruct adaptive immune cells to respond accordingly to different threats. While conventional dendritic cells can be subdivided into two main subtypes, termed cDC1s and cDC2s, it is clear that further heterogeneity exists within these subtypes, particularly for cDC2s. Understanding the signals involved in specifying each of these lineages and subtypes thereof is crucial to (i) enable us to determine their specific functions and (ii) put us in a position to be able to target these cells to promote or prevent a specific function in any given disease setting. Although we still have much to learn regarding the specification of these cells, here we review the most recent advances in our understanding of this and highlight some of the next questions for the future.
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7
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Saito E, Suzuki D, Kurotaki D, Mochizuki A, Manome Y, Suzawa T, Toyoshima Y, Ichikawa T, Funatsu T, Inoue T, Takami M, Tamura T, Inagaki K, Kamijo R. Down-regulation of Irf8 by Lyz2-cre/loxP accelerates osteoclast differentiation in vitro. Cytotechnology 2016; 69:443-450. [PMID: 27502007 PMCID: PMC5461233 DOI: 10.1007/s10616-016-0013-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 07/20/2016] [Indexed: 12/21/2022] Open
Abstract
Interferon regulatory factor 8 (Irf8) is a transcription factor that negatively regulates osteoclast differentiation and Irf8 global knockout (Irf8−/−) mice have been shown to have reduced bone volume resulting from increased osteoclast numbers. However, detailed analysis of the functions of Irf8 in osteoclast precursors with a monocyte/macrophage linage is difficult, because the population and properties of hematopoietic cells in Irf8−/− mice are severely altered. Therefore, to clearly elucidate the functions of Irf8 during osteoclastogenesis, we established myeloid cell-specific Irf8 conditional knockout (Irf8fl/fl;Lyz2cre/+) mice. We found that trabecular bone volume in the Irf8fl/fl;Lyz2cre/+ mice was not significantly affected, while exposure to M-CSF and RANKL significantly increased TRAP activity in vitro in osteoclasts that underwent osteoclastogenesis from bone marrow-derived macrophages (BMMs) induced from bone marrow cells (BMCs) of those mice by addition of M-CSF. Our results also showed that expression of Irf8 mRNA and protein in BMMs obtained from Irf8fl/fl;Lyz2cre/+ mice and cultured with M-CSF was reduced. These findings predicted that Lyz2/Lyz2-cre expression is induced when BMCs differentiate into BMMs in cultures with M-CSF. In osteoclast differentiation cultures, Lyz2 was gradually increased by M-CSF during the first 3 days of culture, then rapidly decreased by the addition of RANKL with M-CSF during the next 3 days. Furthermore, BMCs differentiated into osteoclasts while maintaining a low level of Lyz2 expression when cultured simultaneously with both M-CSF and RANKL from the initiation of culture. These findings suggest that Lyz2-cre expression is induced along with differentiation to BMMs by BMCs obtained from Irf8fl/fl;Lyz2cre/+ mice and cultured with M-CSF. In addition, Irf8 was down-regulated by activation of the cre/loxP recombination system in BMMs and osteoclastogenesis was accelerated. Based on our results, we propose the existence in vivo of a new lineage of osteoclast precursors among BMCs, which differentiate into osteoclasts without up-regulation of Lyz2 expression.
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Affiliation(s)
- Emi Saito
- Departments of Biochemistry, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
- Department of Orthopedic Surgery, School of Medicine, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Dai Suzuki
- Departments of Biochemistry, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan.
| | - Daisuke Kurotaki
- Department of Immunology, Graduate School of Medicine, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa, 236-0004, Japan
| | - Ayako Mochizuki
- Department of Oral Physiology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Yoko Manome
- Departments of Biochemistry, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
- Division of Dentistry for Persons with Disabilities, Department of Special Needs Dentistry, Showa University Dental Hospital, 2-1-1 Kitasenzoku, Ota, Tokyo, 145-8515, Japan
| | - Tetsuo Suzawa
- Departments of Biochemistry, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Yoichi Toyoshima
- Department of Orthopedic Surgery, School of Medicine, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Takahiro Ichikawa
- Departments of Biochemistry, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Takahiro Funatsu
- Division of Dentistry for Persons with Disabilities, Department of Special Needs Dentistry, Showa University Dental Hospital, 2-1-1 Kitasenzoku, Ota, Tokyo, 145-8515, Japan
| | - Tomio Inoue
- Department of Oral Physiology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Masamichi Takami
- Department of Pharmacology, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Tomohiko Tamura
- Department of Immunology, Graduate School of Medicine, Yokohama City University, 3-9 Fukuura, Kanazawa-ku, Yokohama, Kanagawa, 236-0004, Japan
| | - Katsunori Inagaki
- Department of Orthopedic Surgery, School of Medicine, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
| | - Ryutaro Kamijo
- Departments of Biochemistry, School of Dentistry, Showa University, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8555, Japan
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8
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Vermeer JAF, Jansen IDC, Marthi M, Coxon FP, McKenna CE, Sun S, de Vries TJ, Everts V. Jaw bone marrow-derived osteoclast precursors internalize more bisphosphonate than long-bone marrow precursors. Bone 2013; 57:242-51. [PMID: 23962725 DOI: 10.1016/j.bone.2013.08.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Revised: 07/30/2013] [Accepted: 08/02/2013] [Indexed: 11/17/2022]
Abstract
Bisphosphonates (BPs) are widely used in the treatment of several bone diseases, such as osteoporosis and cancers that have metastasized to bone, by virtue of their ability to inhibit osteoclastic bone resorption. Previously, it was shown that osteoclasts present at different bone sites have different characteristics. We hypothesized that BPs could have distinct effects on different populations of osteoclasts and their precursors, for example as a result of a different capacity to endocytose the drugs. To investigate this, bone marrow cells were isolated from jaw and long bone from mice and the cells were primed to differentiate into osteoclasts with the cytokines M-CSF and RANKL. Before fusion occurred, cells were incubated with fluorescein-risedronate (FAM-RIS) for 4 or 24h and uptake was determined by flow cytometry. We found that cultures obtained from the jaw internalized 1.7 to 2.5 times more FAM-RIS than long-bone cultures, both after 4 and 24h, and accordingly jaw osteoclasts were more susceptible to inhibition of prenylation of Rap1a after treatment with BPs for 24h. Surprisingly, differences in BP uptake did not differentially affect osteoclastogenesis. This suggests that jaw osteoclast precursors are less sensitive to bisphosphonates after internalization. This was supported by the finding that gene expression of the anti-apoptotic genes Bcl-2 and Bcl-xL was higher in jaw cells than long bone cells, suggesting that the jaw cells might be more resistant to BP-induced apoptosis. Our findings suggest that bisphosphonates have distinct effects on both populations of osteoclast precursors and support previous findings that osteoclasts and precursors are bone-site specific. This study may help to provide more insights into bone-site-specific responses to bisphosphonates.
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Affiliation(s)
- Jenny A F Vermeer
- Department of Oral Cell Biology and Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, MOVE Research Institute Amsterdam, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands.
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