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Zhao Y, Yang K, Ferreira TA, Kang X, Feng X, Katz J, Michalek SM, Zhang P. Activation of liver X receptors suppresses the abundance and osteoclastogenic potential of osteoclast precursors and periodontal bone loss. Mol Oral Microbiol 2024; 39:125-135. [PMID: 38108557 PMCID: PMC11096071 DOI: 10.1111/omi.12447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 10/25/2023] [Accepted: 12/04/2023] [Indexed: 12/19/2023]
Abstract
Liver-X receptors (LXRs) are essential nuclear hormone receptors involved in cholesterol and lipid metabolism. They are also believed to regulate inflammation and physiological and pathological bone turnover. We have previously shown that infection with the periodontal pathogen Porphyromonas gingivalis (Pg) in mice increases the abundance of CD11b+c-fms+Ly6Chi cells in bone marrow (BM), spleen (SPL), and peripheral blood. These cells also demonstrated enhanced osteoclastogenic activity and a distinctive gene profile following Pg infection. Here, we investigated the role of LXRs in regulating these osteoclast precursors (OCPs) and periodontal bone loss. We found that Pg infection downregulates the gene expression of LXRs, as well as ApoE, a transcription target of LXRs, in CD11b+c-fms+Ly6Chi OCPs. Activation of LXRs by treatment with GW3965, a selective LXR agonist, significantly decreased Pg-induced accumulation of CD11b+c-fms+Ly6Chi population in BM and SPL. GW3965 treatment also significantly suppressed the osteoclastogenic potential of these OCPs induced by Pg infection. Furthermore, the activation of LXRs reduces the abundance of OCPs systemically in BM and locally in the periodontium, as well as mitigates gingival c-fms expression and periodontal bone loss in a ligature-induced periodontitis model. These data implicate a novel role of LXRs in regulating OCP abundance and osteoclastogenic potential in inflammatory bone loss.
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Affiliation(s)
- Yanfang Zhao
- Department of Pediatric Dentistry, School of Dentistry, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kai Yang
- Department of Pediatric Dentistry, School of Dentistry, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Thalyta Amanda Ferreira
- Department of Pediatric Dentistry, School of Dentistry, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Xuejia Kang
- Department of Drug Discovery and Development, Harrison College of Pharmacy, Auburn University, Auburn, Alabama, USA
| | - Xu Feng
- Department of Pathology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jannet Katz
- Department of Pediatric Dentistry, School of Dentistry, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Suzanne M Michalek
- Department of Microbiology, Heersink School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ping Zhang
- Department of Pediatric Dentistry, School of Dentistry, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Shao T, Huang K. Network Pharmacology-Based Analysis on Lonicera japonica for Chronic Osteomyelitis Treatment. JOURNAL OF ONCOLOGY 2022; 2022:1706716. [PMID: 35111224 PMCID: PMC8803426 DOI: 10.1155/2022/1706716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 01/07/2022] [Indexed: 01/18/2023]
Abstract
MATERIALS AND METHODS Active compounds of LJP were examined established on the analysis platform, Traditional Chinese Medicine Systems Pharmacology (TCMSP) database. DrugBank identified drug targets and annotated them on UniPort and GeneCards. Besides, the COM-related genes were identified on GeneCards. The network of the drug, main active compounds, targets, and diseases was built utilizing Cytoscape. STRING was utilized to build the protein-protein interaction network. Moreover, the KEGG and GO pathway enrichment analysis were applied to analyze biological function. RESULTS 23 active compounds of LJP were screened, and 204 drug targets and 686 COM-related genes were identified. Forty-five intersection genes were overlapped from 204 drug targets and 686 COM-related genes. The drug-active compounds-target protein-diseases network was established based on 23 active compounds of LJP and 45 intersection genes. Moreover, the interaction of 45 intersection genes was explored by the PPI network, and the drug-active compounds-target protein-diseases network was formed grounded by 23 active compounds of LJP, 45 intersection genes, and PPI network. The KEGG and GO pathway enrichment analysis specified that 45 intersection genes primarily enriched in immune-related pathways and oxidative stress-related pathways. CONCLUSIONS In the research done, the main active compounds of LJP and drug targets in the treatment of COM were identified. Our findings might provide the ingredient option of LJP and drug targets of LJP in COM treatment.
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Affiliation(s)
- Tingting Shao
- Infectious Disease Department, Tongde Hospital of Zhejiang Province, 234# Gu-cui Road, Hangzhou 310012, China
| | - Kai Huang
- Department of Orthopedics, Tongde Hospital of Zhejiang Province, 234# Gu-cui Road, Hangzhou 310012, China
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Goel D, Vohora D. Liver X receptors and skeleton: Current state-of-knowledge. Bone 2021; 144:115807. [PMID: 33333244 DOI: 10.1016/j.bone.2020.115807] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 11/26/2020] [Accepted: 12/11/2020] [Indexed: 12/25/2022]
Abstract
The liver X receptors (LXR) is a nuclear receptor that acts as a prominent regulator of lipid homeostasis and inflammatory response. Its therapeutic effectiveness against various diseases like Alzheimer's disease and atherosclerosis has been investigated in detail. Emerging pieces of evidence now reveal that LXR is also a crucial modulator of bone remodeling. However, the molecular mechanisms underlying the pharmacological actions of LXR on the skeleton and its role in osteoporosis are poorly understood. Therefore, in the current review, we highlight LXR and its actions through different molecular pathways modulating skeletal homeostasis. The studies described in this review propound that LXR in association with estrogen, PTH, PPARγ, RXR hedgehog, and canonical Wnt signaling regulates osteoclastogenesis and bone resorption. It regulates RANKL-induced expression of c-Fos, NFATc1, and NF-κB involved in osteoclast differentiation. Additionally, several studies suggest suppression of RANKL-induced osteoclast differentiation by synthetic LXR ligands. Given the significance of modulation of LXR in various physiological and pathological settings, our findings indicate that therapeutic targeting of LXR might potentially prevent or treat osteoporosis and improve bone quality.
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Affiliation(s)
- Divya Goel
- Department of Pharmacology, School of Pharmaceutical Education and Research (SPER), Jamia Hamdard, New Delhi 110062, India
| | - Divya Vohora
- Department of Pharmacology, School of Pharmaceutical Education and Research (SPER), Jamia Hamdard, New Delhi 110062, India.
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Moradifard S, Hoseinbeyki M, Emam MM, Parchiniparchin F, Ebrahimi-Rad M. Association of the Sp1 binding site and -1997 promoter variations in COL1A1 with osteoporosis risk: The application of meta-analysis and bioinformatics approaches offers a new perspective for future research. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2020; 786:108339. [PMID: 33339581 DOI: 10.1016/j.mrrev.2020.108339] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 08/11/2020] [Accepted: 10/06/2020] [Indexed: 12/21/2022]
Abstract
As a complex disease, osteoporosis is influenced by several genetic markers. Many studies have examined the link between the Sp1 binding site +1245 G > T (rs1800012) and -1997 G > T (rs1107946) variations in the COL1A1 gene with osteoporosis risk. However, the findings of these studies have been contradictory; therefore, we performed a meta-analysis to aggregate additional information and obtain increased statistical power to more efficiently estimate this correlation. A meta-analysis was conducted with studies published between 1991-2020 that were identified by a systematic electronic search of the Scopus and Clarivate Analytics databases. Studies with bone mineral density (BMD) data and complete genotypes of the single-nucleotide variations (SNVs) for the overall and postmenopausal female population were included in this meta-analysis and analyzed using the R metaphor package. A relationship between rs1800012 and significantly decreased BMD values at the lumbar spine and femoral neck was found in individuals carrying the "ss" versus the "SS" genotype in the overall population according to a random effects model (p < 0.0001). Similar results were also found in the postmenopausal female population (p = 0.003 and 0.0002, respectively). Such findings might be an indication of increased osteoporosis risk in both studied groups in individuals with the "ss" genotype. Although no association was identified between the -1997 G > T and low BMD in the overall population, those individuals with the "GT" genotype showed a higher level of BMD than those with "GG" in the subgroup analysis (p = 0.007). To determine which transcription factor (TF) might bind to the -1997 G > T in COL1A1, 45 TFs were identified based on bioinformatics predictions. According to the GSE35958 microarray dataset, 16 of 45 TFs showed differential expression profiles in osteoporotic human mesenchymal stem cells relative to normal samples from elderly donors. By identifying candidate TFs for the -1997 G > T site, our study offers a new perspective for future research.
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Affiliation(s)
| | | | - Mohammad Mehdi Emam
- Rheumatology Ward, Loghman Hospital, Shahid Beheshti Medical University (SBMU), Tehran, Iran
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Nuclear receptors in osteoclasts. Curr Opin Pharmacol 2020; 53:8-17. [PMID: 32569976 DOI: 10.1016/j.coph.2020.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 03/09/2020] [Accepted: 03/23/2020] [Indexed: 02/08/2023]
Abstract
Osteoclasts are bone-resorbing cells that play an essential role in the remodeling of bone under physiological conditions and numerous pathological conditions, such as osteoporosis, bone metastasis, and inflammatory bone erosion. Nuclear receptors are crucial to various physiological processes, including metabolism, development and inflammation, and function as transcription factors to activate target genes. Synthetic ligands of nuclear receptors are also available for the treatment of metabolic and inflammatory diseases. However, dysregulated bone phenotypes have been documented in patients who take synthetic nuclear receptor ligands as a therapy. Therefore, the effect of nuclear receptors on bone cells has become an important area of exploration; additionally, the molecular mechanisms underlying the action of nuclear receptors in osteoclasts have not been completely understood. Here, we cover the recent progress in our understanding of the roles of nuclear receptors in osteoclasts.
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Long W, Quan J, Liu Y, Li J, Gong Q, Jiang H. 7ND protein exerts inhibitory effects on both osteoclast differentiation in vitro and lipopolysaccharide‑induced bone erosion in vivo. Mol Med Rep 2020; 22:97-104. [PMID: 32377737 PMCID: PMC7248529 DOI: 10.3892/mmr.2020.11119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 02/25/2020] [Indexed: 11/29/2022] Open
Abstract
Excessive numbers of osteoclasts are responsible for inflammation-induced osteolysis. Identification of osteoclast-targeting agents may facilitate the development of a novel therapeutic approach for the treatment of pathological bone loss. Seven-amino acid truncated (7ND) protein, a mutant form of monocyte chemoattractant protein-1 (MCP-1), functions as a competitive inhibitor of MCP-1. However, the effects of 7ND protein on osteoclast differentiation remain unknown. Therefore, in the present study, the effects of 7ND protein on osteoclast differentiation induced by tumour necrosis factor superfamily member 11 were investigated. In the present study, 7ND protein inhibited the osteoclast differentiation of peripheral blood mononuclear cells without influencing cell proliferation. Furthermore, to evaluate the effects of 7ND protein in vivo, a lipopolysaccharide (LPS)-induced calvarial bone erosion animal model was established. The 7ND protein remarkably attenuated LPS-induced bone resorption, as assessed by micro-computed tomography and histological analysis. Taken together, the present results suggested the feasibility of local delivery of 7ND protein to mitigate osteoclast differentiation and LPS-induced osteolysis, which may represent a potential approach to treat inflammatory bone destruction.
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Affiliation(s)
- Weilin Long
- Department of Stomatology, The Third Affiliated Hospital of Sun Yat‑sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Jingjing Quan
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat‑sen University, Guangzhou, Guangdong 510055, P.R. China
| | - Yiwen Liu
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat‑sen University, Guangzhou, Guangdong 510055, P.R. China
| | - Jing Li
- Department of Stomatology, Affiliated Longhua People's Hospital, Southern Medical University, Shenzhen, Guangdong 518000, P.R. China
| | - Qimei Gong
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat‑sen University, Guangzhou, Guangdong 510055, P.R. China
| | - Hongwei Jiang
- Department of Operative Dentistry and Endodontics, Guanghua School of Stomatology, Hospital of Stomatology, Sun Yat‑sen University, Guangzhou, Guangdong 510055, P.R. China
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Tanaka T, Takei Y, Zaima N, Moriyama T, Yamanouchi D. Hyperglycemia Suppresses RANKL-Induced Osteoclast Differentiation through LXRβ Expression in RAW264.7 Cells. J Nutr Sci Vitaminol (Tokyo) 2017; 63:28-34. [PMID: 28367923 DOI: 10.3177/jnsv.63.28] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
There have been reports that hyperglycemia suppresses osteoclast (OCL) differentiation, although the underlying mechanism is poorly understood. Here we demonstrated that high glucose suppresses OCL differentiation through activation of liver X receptor (LXR) β, a recently reported glucose-sensing nuclear receptor. The effect of hyperglycemia on osteoclastogenesis was tested in RAW264.7 cells, a murine macrophage cell line. Cells were treated with receptor activator of NF-κB ligand (RANKL) under normoglycemic (5.5 mM glucose), normoglycemic with high osmotic pressure (5.5 mM glucose + 10.0 mM mannitol), and hyperglycemic (15.5 mM glucose) conditions. RANKL-induced osteoclastogenesis was significantly suppressed by high-glucose treatment. Mannitol treatment also significantly suppressed osteoclastogenesis, but the inhibitory effect was lower than for high-glucose treatment. The suppression of mRNA expression of Lxrβ by RANKL was significantly restored by high glucose, but not mannitol. Additionally, the deactivation of Lxrβ by siRNA attenuated high-glucose-induced suppression of osteoclastogenesis. Although further validation of the underlying pathway is necessary, targeting LXRβ is a potential therapeutic approach to treating osteoporosis.
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Affiliation(s)
- Teruyoshi Tanaka
- Division of Vascular Surgery, Department of Surgery, University of Wisconsin School of Medicine and Public Health
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Abstract
Nuclear receptors are a family of transcription factors that can be activated by lipophilic ligands. They are fundamental regulators of development, reproduction, and energy metabolism. In bone, nuclear receptors enable bone cells, including osteoblasts, osteoclasts, and osteocytes, to sense their dynamic microenvironment and maintain normal bone development and remodeling. Our views of the molecular mechanisms in this process have advanced greatly in the past decade. Drugs targeting nuclear receptors are widely used in the clinic for treating patients with bone disorders such as osteoporosis by modulating bone formation and resorption rates. Deficiency in the natural ligands of certain nuclear receptors can cause bone loss; for example, estrogen loss in postmenopausal women leads to osteoporosis and increases bone fracture risk. In contrast, excessive ligands of other nuclear receptors, such as glucocorticoids, can also be detrimental to bone health. Nonetheless, the ligand-induced osteoprotective effects of many other nuclear receptors, e.g., vitamin D receptor, are still in debate and require further characterizations. This review summarizes previous studies on the roles of nuclear receptors in bone homeostasis and incorporates the most recent findings. The advancement of our understanding in this field will help researchers improve the applications of agonists, antagonists, and selective modulators of nuclear receptors for therapeutic purposes; in particular, determining optimal pharmacological drug doses, preventing side effects, and designing new drugs that are more potent and specific.
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Jin L, Batra S, Jeyaseelan S. Deletion of Nlrp3 Augments Survival during Polymicrobial Sepsis by Decreasing Autophagy and Enhancing Phagocytosis. THE JOURNAL OF IMMUNOLOGY 2016; 198:1253-1262. [PMID: 28031338 DOI: 10.4049/jimmunol.1601745] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 11/25/2016] [Indexed: 01/07/2023]
Abstract
NLRP3 inflammasome is a critical player in innate immunity. Neutrophil recruitment to tissues and effective neutrophil function are critical innate immune mechanisms for bacterial clearance. However, the role of NLRP3 in neutrophil-dependent bacterial clearance in polymicrobial sepsis is unclear. In this study, we evaluated the role of NLRP3 in polymicrobial sepsis induced by cecal ligation and puncture (CLP). Our results showed protection from death in NLRP3-deficient (Nlrp3-/-) and NLRP3 inhibitor-treated wild-type (C57BL/6) mice. Nlrp3-/- and NLRP3 inhibitor-treated mice displayed lower bacterial load but no impairment in neutrophil recruitment to peritoneum. However, neutrophil depletion abrogated protection from death in Nlrp3-/- mice in response to CLP. Intriguingly, following CLP, Nlrp3-/- peritoneal cells (primarily neutrophils) demonstrate decreased autophagy, augmented phagocytosis, and enhanced scavenger receptor (macrophage receptor with collagenous structure) and mannose-binding leptin expression. These findings enhance our understanding of the critical role of NLRP3 in modulating autophagy and phagocytosis in neutrophils and suggest that therapies should be targeted to modulate autophagy and phagocytosis in neutrophils to control bacterial burden in tissues during CLP-induced polymicrobial sepsis.
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Affiliation(s)
- Liliang Jin
- Laboratory of Lung Biology, Department of Pathobiological Sciences and Center for Experimental Infectious Disease Research, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803; and
| | - Sanjay Batra
- Laboratory of Lung Biology, Department of Pathobiological Sciences and Center for Experimental Infectious Disease Research, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803; and
| | - Samithamby Jeyaseelan
- Laboratory of Lung Biology, Department of Pathobiological Sciences and Center for Experimental Infectious Disease Research, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803; and .,Division of Pulmonary and Critical Care, Department of Medicine, LSU Health Sciences Center, New Orleans, LA 70112
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10
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Tanaka T, Takei Y, Yamanouchi D. Hyperglycemia Suppresses Calcium Phosphate-Induced Aneurysm Formation Through Inhibition of Macrophage Activation. J Am Heart Assoc 2016; 5:e003062. [PMID: 27021877 PMCID: PMC4943277 DOI: 10.1161/jaha.115.003062] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Background The aim of this study was to elucidate aspects of diabetes mellitus–induced suppression of aneurysm. We hypothesized that high glucose suppresses aneurysm by inhibiting macrophage activation via activation of Nr1h2 (also known as liver X receptor β), recently characterized as a glucose‐sensing nuclear receptor. Methods and Results Calcium phosphate (CaPO4)–induced aneurysm formation was significantly suppressed in the arterial wall in type 1 and 2 diabetic mice. A murine macrophage cell line, RAW264.7, was treated with tumor necrosis factor α (TNF‐α) plus CaPO4 and showed a significant increase in matrix metalloproteinase 9 (Mmp9) mRNA and secreted protein expression compared with TNF‐α alone. Elevated Mmp9 expression was significantly suppressed by hyperglycemic conditions (15.5 mmol/L glucose) compared with normoglycemic conditions (5.5 mmol/L glucose) or normoglycemic conditions with high osmotic pressure (5.5 mmol/L glucose +10.0 mmol/L mannitol). Nr1h2 mRNA and protein expression were suppressed by treatment with TNF‐α plus CaPO4 but were restored by hyperglycemic conditions. Activation of Nr1h2 by the antagonist GW3965 during stimulation with TNF‐α plus CaPO4 mimicked hyperglycemic conditions and inhibited Mmp9 upregulation, whereas the deactivation of Nr1h2 by small interfering RNA (siRNA) under hyperglycemic conditions canceled the suppressive effect and restored Mmp9 expression induced by TNF‐α plus CaPO4. Moreover, Nr1h2 activation with GW3965 significantly suppressed CaPO4‐induced aneurysm in mice compared with vehicle‐injected control mice. Conclusions Our results show that hyperglycemia suppresses macrophage activation and aneurysmal degeneration through the activation of Nr1h2. Although further validation of the underlying pathway is necessary, targeting Nr1h2 is a potential therapeutic approach to treating aneurysm.
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Affiliation(s)
- Teruyoshi Tanaka
- Division of Vascular Surgery, Department of Surgery, Wisconsin Institute for Medical Research, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Yuichiro Takei
- Division of Vascular Surgery, Department of Surgery, Wisconsin Institute for Medical Research, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - Dai Yamanouchi
- Division of Vascular Surgery, Department of Surgery, Wisconsin Institute for Medical Research, University of Wisconsin School of Medicine and Public Health, Madison, WI
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Huang N, Shaik-Dasthagirisaheb YB, LaValley MP, Gibson FC. Liver X receptors contribute to periodontal pathogen-elicited inflammation and oral bone loss. Mol Oral Microbiol 2015; 30:438-50. [PMID: 25946408 DOI: 10.1111/omi.12103] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/01/2015] [Indexed: 12/29/2022]
Abstract
Periodontal diseases are chronic oral inflammatory diseases that are polymicrobial in nature. The presence of specific bacteria in subgingival plaque such as Porphyromonas gingivalis is associated with microbial dysbiosis and the modulation of host immune response. Bacterially elicited innate immune activation and inflammation are key elements implicated in the destruction of soft and hard tissues supporting the teeth. Liver X receptors (LXRs) are nuclear hormone receptors with important function in lipid homeostasis, inflammation, and host response to infection; however, their contribution to chronic inflammatory diseases such as periodontal disease is not understood. The aim of this study was to define the contribution of LXRs in the development of immune response to P. gingivalis and to assess the roles that LXRs play in infection-elicited oral bone loss. Employing macrophages, we observed that P. gingivalis challenge led to reduced LXRα and LXRβ gene expression compared with that observed with unchallenged wild-type cells. Myeloid differentiation primary response gene 88 (MyD88)-independent, Toll/interleukin-1 receptor-domain-containing adapter-inducing interferon-β (TRIF)-dependent signaling affected P. gingivalis-mediated reduction in LXRα expression, whereas neither pathway influenced the P. gingivalis effect on LXRβ expression. Employing LXR agonist and mice deficient in LXRs, we observed functional effects of LXRs in the development of a P. gingivalis-elicited cytokine response at the level of the macrophage, and participation of LXRs in P. gingivalis-elicited oral bone loss. These findings identify novel importance for LXRs in the pathogenesis of P. gingivalis infection-elicited inflammation and oral bone loss.
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Affiliation(s)
- N Huang
- Section of Infectious Diseases, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Y B Shaik-Dasthagirisaheb
- Section of Infectious Diseases, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - M P LaValley
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - F C Gibson
- Section of Infectious Diseases, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
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Jin Z, Li X, Wan Y. Minireview: nuclear receptor regulation of osteoclast and bone remodeling. Mol Endocrinol 2014; 29:172-86. [PMID: 25549044 DOI: 10.1210/me.2014-1316] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Osteoclasts are bone-resorbing cells essential for skeletal remodeling and regeneration. However, excessive osteoclasts often contribute to prevalent bone degenerative diseases such as osteoporosis, arthritis, and cancer bone metastasis. Osteoclast dysregulation is also associated with rare disorders such as osteopetrosis, pycnodysostosis, Paget's disease, and Gorham-Stout syndrome. The nuclear receptor (NR) family of transcription factors functions as metabolic sensors that control a variety of physiological processes including skeletal homeostasis and serves as attractive therapeutic targets for many diseases. In this review, we highlight recent findings on the new players and the new mechanisms for how NRs regulate osteoclast differentiation and bone resorption. An enhanced understanding of NR functions in osteoclastogenesis will facilitate the development of not only novel osteoprotective medicine but also prudent strategies to minimize the adverse skeletal effects of certain NR-targeting drugs for a better treatment of cancer and metabolic diseases.
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Affiliation(s)
- Zixue Jin
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
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Steffensen KR, Jakobsson T, Gustafsson JÅ. Targeting liver X receptors in inflammation. Expert Opin Ther Targets 2013; 17:977-90. [PMID: 23738533 DOI: 10.1517/14728222.2013.806490] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION The two oxysterol receptors, 'liver X receptors (LXRs)' LXRα and LXRβ, are amongst the emerging newer drug targets within the nuclear receptor family and targeting LXRs represents novel strategies needed for prevention and treatment of diseases where current therapeutics is inadequate. AREAS COVERED This review discusses the current understanding of LXR biology with an emphasis on the molecular aspects of LXR signalling establishing their potential as drug targets. Recent advances of their transcriptional mechanisms in inflammatory pathways and their physiological roles in inflammation and immunity are described. EXPERT OPINION The new discoveries of LXR-regulated inflammatory pathways have ignited new promises for LXRs as drug targets. The broad physiological roles of LXRs involve a high risk of unwanted side effects. Recent insights into LXR biology of the brain indicate a highly important role in neuronal development and a clinical trial testing an LXR agonist reported adverse neurological side effects. This suggests that drug development must focus on limiting the range of LXR signalling - possibly achieved through subtype, tissue specific, promoter specific or pathway specific activation of LXRs where a successful candidate drug must be carefully studied for its effect in the central nervous system.
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Affiliation(s)
- Knut R Steffensen
- Karolinska Institutet, Center for Biosciences, Department of Biosciences and Nutrition, S-14183 Stockholm, Sweden.
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Robertson Remen KM, Gustafsson JÅ, Andersson G. The liver X receptor promotes macrophage differentiation and suppresses osteoclast formation in mouse RAW264.7 promyelocytic leukemia cells exposed to bacterial lipopolysaccharide. Biochem Biophys Res Commun 2012; 430:375-80. [PMID: 23159616 DOI: 10.1016/j.bbrc.2012.11.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 11/04/2012] [Indexed: 11/26/2022]
Abstract
Lipopolysaccharide (LPS), the principal component of Gram-negative bacterial cell walls, is a stimulator of osteoclastogenesis and thus a key factor in inflammatory bone loss. We have recently reported that the important cholesterol and inflammatory regulator, liver X receptor (LXRα/β), can potently inhibit osteoclast formation from bone marrow-derived osteoclast precursors in a bacterial/LPS environment. In this manuscript, we further studied the effect of the LXR agonist GW3965 on osteoclast differentiation in RAW264.7 promyelocytic leukemia cells exposed to LPS. We found that not only did activation of the LXR potently inhibit the formation of TRAP-positive osteoclast-like cells, but promoted a population of TRAP-negative mononuclear cells with high phagocytic activity. We observed reduced expression of the osteoclast markers TRAP/Acp5, Ctsk, Calcr and Oscar after 3-4days of GW3965 treatment, coinciding with an increase in the expression of the anti-osteoclastogenic factor Irf8. Expression of the macrophage/phagocytic marker Cd68 was increased, however the "classical" macrophage markers F4/80 and Cd14 and the "alternatively" activated macrophage markers Tgfβ and Il10 were not altered. Further, activation of LXR increased the expression of the macrophage survival gene AIM/SPα, a known LXR target gene, and osteoclast/macrophage-related markers (Mitf, Pu.1, Usf1/2, Ostm1 and Mfr). Although Akt phosphorylation was reduced, GW3965 seemed to act independently of MAPKs (p38, ERK, JNK) and NFκB, and had no inhibitory effect on cytokine expression (Tnfα, Il6, or Il1β). Our results indicate that activation of the LXR not only inhibits the differentiation of osteoclast-like cells from RAW264.7 cells in a bacterial/LPS environment, but is also involved in the fate determination of myeloid progenitor cells into macrophages with high phagocytic capacity.
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