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  • 1
    In: Journal of Bone and Mineral Research, Wiley, Vol. 35, No. 2 ( 2020-02), p. 382-395
    Abstract: Periodontitis is a bacterially induced chronic inflammatory condition of the oral cavity where tooth‐supporting tissues including alveolar bone are destructed. Previously, we have shown that the adaptor protein SH3‐domain binding protein 2 (SH3BP2) plays a critical role in inflammatory response and osteoclastogenesis of myeloid lineage cells through spleen tyrosine kinase (SYK). In this study, we show that SH3BP2 is a novel regulator for alveolar bone resorption in periodontitis. Micro‐CT analysis of SH3BP2‐deficient ( Sh3bp2 −/− ) mice challenged with ligature‐induced periodontitis revealed that Sh3bp2 −/− mice develop decreased alveolar bone loss (male 14.9% ± 10.2%; female 19.0% ± 6.0%) compared with wild‐type control mice (male 25.3% ± 5.8%; female 30.8% ± 5.8%). Lack of SH3BP2 did not change the inflammatory cytokine expression and osteoclast induction. Conditional knockout of SH3BP2 and SYK in myeloid lineage cells with LysM‐Cre mice recapitulated the reduced bone loss without affecting both inflammatory cytokine expression and osteoclast induction, suggesting that the SH3BP2‐SYK axis plays a key role in regulating alveolar bone loss by mechanisms that regulate the bone‐resorbing function of osteoclasts rather than differentiation. Administration of a new SYK inhibitor GS‐9973 before or after periodontitis induction reduced bone resorption without affecting inflammatory reaction in gingival tissues. In vitro, GS‐9973 treatment of bone marrow–derived M‐CSF‐dependent macrophages suppressed tartrate‐resistant acid phosphatase (TRAP)‐positive osteoclast formation with decreased mineral resorption capacity even when GS‐9973 was added after RANKL stimulation. Thus, the data suggest that SH3BP2‐SYK is a novel signaling axis for regulating alveolar bone loss in periodontitis and that SYK can be a potential therapeutic target to suppress alveolar bone resorption in periodontal diseases. © 2019 American Society for Bone and Mineral Research. © 2019 American Society for Bone and Mineral Research.
    Type of Medium: Online Resource
    ISSN: 0884-0431 , 1523-4681
    URL: Issue
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    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2008867-X
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  • 2
    In: Journal of Bone and Mineral Research, Wiley, Vol. 33, No. 8 ( 2018-08), p. 1513-1519
    Abstract: Cherubism is a craniofacial disorder characterized by maxillary and mandibular bone destruction. Gain‐of‐function mutations in the SH3‐domain binding protein 2 (SH3BP2) are responsible for the excessive bone resorption caused by fibrous inflammatory lesions. A homozygous knock‐in (KI) mouse model for cherubism ( Sh3bp2 KI/KI ) develops autoinflammation resulting in systemic bone destruction. Although administration of the TNF‐α blocker etanercept to neonatal Sh3bp2 KI/KI mice prevented the disease onset, this therapy was not effective for adult Sh3bp2 KI/KI mice or human cherubism patients who already had lesions. Because genetic ablation of spleen tyrosine kinase (SYK) in myeloid cells rescues Sh3bp2 KI/KI mice from inflammation, we examined whether SYK inhibitor administration can improve fully developed cherubism symptoms in adult Sh3bp2 KI/KI mice. Entospletinib (GS‐9973) was intraperitoneally injected into 10‐week‐old Sh3bp2 KI/KI mice every day for 6 weeks. Treatment with GS‐9973 improved facial swelling and histomorphometric analysis of lung and liver tissue showed that GS‐9973 administration significantly reduced inflammatory infiltrates associated with decreased levels of serum TNF‐α. Micro–computed tomography (μCT) analysis showed that GS‐9973 treatment reduced bone erosion in mandibles, calvariae, and ankle and elbow joints of Sh3bp2 KI/KI mice compared to Sh3bp2 KI/KI mice treated with dimethyl sulfoxide (DMSO). Taken together, the results demonstrate that administration of the SYK inhibitor ameliorates an already established cherubism phenotype in mice, suggesting that pharmacological inhibition of SYK may be a treatment option for cherubism patients with active disease progression. © 2018 American Society for Bone and Mineral Research.
    Type of Medium: Online Resource
    ISSN: 0884-0431 , 1523-4681
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 2008867-X
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  • 3
    In: Journal of Bone and Mineral Research, Wiley, Vol. 29, No. 5 ( 2014-05), p. 1170-1182
    Abstract: Cherubism is a genetic disorder of the craniofacial skeleton caused by gain‐of‐function mutations in the signaling adaptor protein, SH3‐domain binding protein 2 (SH3BP2). In a knock‐in mouse model for cherubism, we previously demonstrated that homozygous mutant mice develop T/B cell–independent systemic macrophage inflammation leading to bone erosion and joint destruction. Homozygous mice develop multiostotic bone lesions whereas cherubism lesions in humans are limited to jawbones. We identified a critical role of tumor necrosis factor α (TNF‐α) in the development of autoinflammation by creating homozygous TNF‐α‐deficient cherubism mutants, in which systemic inflammation and bone destruction were rescued. In this study, we examined whether postnatal administration of an anti‐TNF‐α antagonist can prevent or ameliorate the disease progression in cherubism mice. Neonatal homozygous mutants, in which active inflammation has not yet developed, were treated with a high dose of etanercept (25 mg/kg, twice/week) for 7 weeks. Etanercept‐treated neonatal mice showed strong rescue of facial swelling and bone loss in jaws and calvariae. Destruction of joints was fully rescued in the high‐dose group. Moreover, the high‐dose treatment group showed a significant decrease in lung and liver inflammatory lesions. However, inflammation and bone loss, which were successfully treated by etanercept administration, recurred after etanercept discontinuation. No significant effect was observed in low‐dose–treated (0.5 mg/kg, twice/week) and vehicle‐treated groups. In contrast, when 10‐week‐old cherubism mice with fully active inflammation were treated with etanercept for 7 weeks, even the high‐dose administration did not decrease bone loss or lung or liver inflammation. Taken together, the results suggest that anti‐TNF‐α therapy may be effective in young cherubism patients, if treated before the inflammatory phase or bone resorption occurs. Therefore, early genetic diagnosis and early treatment with anti‐TNF‐α antagonists may be able to prevent or ameliorate cherubism, especially in patients with a mutation in SH3BP2 . © 2014 American Society for Bone and Mineral Research.
    Type of Medium: Online Resource
    ISSN: 0884-0431 , 1523-4681
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 2008867-X
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  • 4
    In: Journal of Bone and Mineral Research, Wiley, Vol. 29, No. 12 ( 2014-12), p. 2618-2635
    Abstract: Cherubism (OMIM# 118400) is a genetic disorder with excessive jawbone resorption caused by mutations in SH3 domain binding protein 2 (SH3BP2), a signaling adaptor protein. Studies on the mouse model for cherubism carrying a P416R knock‐in (KI) mutation have revealed that mutant SH3BP2 enhances tumor necrosis factor (TNF)‐α production and receptor activator of nuclear factor‐κB ligand (RANKL)‐induced osteoclast differentiation in myeloid cells. TNF‐α is expressed in human cherubism lesions, which contain a large number of tartrate‐resistant acid phosphatase (TRAP)‐positive multinucleated cells, and TNF‐α plays a critical role in inflammatory bone destruction in homozygous cherubism mice ( Sh3bp2 KI/KI ). The data suggest a pathophysiological relationship between mutant SH3BP2 and TNF‐α–mediated bone loss by osteoclasts. Therefore, we investigated whether P416R mutant SH3BP2 is involved in TNF‐α–mediated osteoclast formation and bone loss. Here, we show that bone marrow–derived M‐CSF–dependent macrophages (BMMs) from the heterozygous cherubism mutant ( Sh3bp2 KI/+ ) mice are highly responsive to TNF‐α and can differentiate into osteoclasts independently of RANKL in vitro by a mechanism that involves spleen tyrosine kinase (SYK) and phospholipase Cγ2 (PLCγ2) phosphorylation, leading to increased nuclear translocation of NFATc1. The heterozygous cherubism mutation exacerbates bone loss with increased osteoclast formation in a mouse calvarial TNF‐α injection model as well as in a human TNF‐α transgenic mouse model (hTNFtg). SH3BP2 knockdown in RAW264.7 cells results in decreased TRAP‐positive multinucleated cell formation. These findings suggest that the SH3BP2 cherubism mutation can cause jawbone destruction by promoting osteoclast formation in response to TNF‐α expressed in cherubism lesions and that SH3BP2 is a key regulator for TNF‐α–induced osteoclastogenesis. Inhibition of SH3BP2 expression in osteoclast progenitors could be a potential strategy for the treatment of bone loss in cherubism as well as in other inflammatory bone disorders. © 2014 American Society for Bone and Mineral Research.
    Type of Medium: Online Resource
    ISSN: 0884-0431 , 1523-4681
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 2008867-X
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  • 5
    In: Bone, Elsevier BV, Vol. 106 ( 2018-01), p. 156-166
    Type of Medium: Online Resource
    ISSN: 8756-3282
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2018
    detail.hit.zdb_id: 1496324-3
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  • 6
    In: Journal of Periodontology, Wiley, Vol. 94, No. 2 ( 2023-02), p. 277-289
    Abstract: Type 1 diabetes mellitus (T1DM) and periodontitis have long been thought to be biologically connected. Indeed, T1DM is a risk factor for periodontal disease. With the population of diabetic individuals growing, it is more important than ever to understand the negative consequences of diabetes on the periodontium and the mechanisms. The aim of this study was to find out the early effects of T1DM on the periodontium without any experimentally induced periodontitis. Methods We established the streptozotocin (STZ)‐induced diabetic mouse model and examined the periodontium 8 weeks later by histology, molecular and cellular assays. Microcomputed tomographic ( 𝜇 CT) imaging and in vivo fluorochrome labeling were also used to quantify bone volume and mineral apposition rates (MAR). Results The histologic appearance of epithelium tissue, connective tissue, and periodontal ligament in the diabetic condition was comparable with that of control mice. However, immune cell infiltration in the gingiva was dramatically elevated in the diabetic mice, which was accompanied by unmineralized connective tissue degeneration. Bone resorption activity was significantly increased in the diabetic mice, and quantitative 𝜇 CT demonstrated the bone volume, the ratio of bone volume over tissue volume, and cemento‐enamel junction to alveolar bone crest (CEJ‐ABC) in the diabetic condition were equivalent to those in the control group. In vivo fluorochrome labeling revealed increased MAR and bone remodeling in the diabetic mice. Further investigation found the diabetic mice had more osteoprogenitors recruited to the periodontium, allowing more bone formation to balance the enhanced bone resorption. Conclusions STZ‐induced T1DM mice, at an early stage, have elevated gingival inflammation and soft tissue degeneration and increased bone resorption; but still the alveolar bone was preserved by recruiting more osteoprogenitor cells and increasing the rate of bone formation. We conclude that inflammation and periodontitis precede alveolar bone deterioration in diabetes.
    Type of Medium: Online Resource
    ISSN: 0022-3492 , 1943-3670
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 2040047-0
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  • 7
    Online Resource
    Online Resource
    Elsevier BV ; 2020
    In:  Bone Reports Vol. 12 ( 2020-06), p. 100258-
    In: Bone Reports, Elsevier BV, Vol. 12 ( 2020-06), p. 100258-
    Type of Medium: Online Resource
    ISSN: 2352-1872
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
    detail.hit.zdb_id: 2821774-3
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  • 8
    In: JBMR Plus, Wiley, Vol. 4, No. 6 ( 2020-06)
    Abstract: Cherubism (OMIM#118400) is a craniofacial disorder characterized by destructive jaw expansion. Gain‐of‐function mutations in SH3‐domain binding protein 2 (SH3BP2) are responsible for this rare disorder. We have previously shown that homozygous knock‐in (KI) mice ( Sh3bp2 KI/KI ) recapitulate human cherubism by developing inflammatory lesions in the jaw. However, it remains unknown why heterozygous KI mice ( Sh3bp2 KI/+ ) do not recapitulate the excessive jawbone destruction in human cherubism, even though all mutations are heterozygous in humans. We hypothesized that Sh3bp2 KI/+ mice need to be challenged for developing exacerbated jawbone destruction and that bacterial stimulation in the oral cavity may be involved in the mechanism. In this study, we applied a ligature‐induced periodontitis model to Sh3bp2 KI/+ mice to induce inflammatory alveolar bone destruction. Ligature placement induced alveolar bone resorption with gingival inflammation. Quantification of alveolar bone volume revealed that Sh3bp2 KI/+ mice developed more severe bone loss (male: 43.0% ± 10.6%, female: 42.6% ± 10.4%) compared with Sh3bp2 +/+ mice (male: 25.8% ± 4.0%, female: 30.9% ± 6.5%). Measurement of bone loss by the cement‐enamel junction–alveolar bone crest distance showed no difference between Sh3bp2 KI/+ and Sh3bp2 +/+ mice. The number of osteoclasts on the alveolar bone surface was higher in male Sh3bp2 KI/+ mice, but not in females, compared with Sh3bp2 +/+ mice. In contrast, inflammatory cytokine levels in gingiva were comparable between Sh3bp2 KI/+ and Sh3bp2 +/+ mice with ligatures. Genetic deletion of the spleen tyrosine kinase in myeloid cells and antibiotic treatment suppressed alveolar bone loss in Sh3bp2 KI/+ mice, suggesting that increased osteoclast differentiation and function mediated by SYK and accumulation of oral bacteria are responsible for the increased alveolar bone loss in Sh3bp2 KI/+ mice with ligature‐induced periodontitis. High amounts of oral bacterial load caused by insufficient oral hygiene could be a trigger for the initiation of jawbone destruction in human cherubism. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
    Type of Medium: Online Resource
    ISSN: 2473-4039 , 2473-4039
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2905710-3
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  • 9
    In: PLoS ONE, Public Library of Science (PLoS), Vol. 9, No. 8 ( 2014-8-21), p. e105518-
    Type of Medium: Online Resource
    ISSN: 1932-6203
    Language: English
    Publisher: Public Library of Science (PLoS)
    Publication Date: 2014
    detail.hit.zdb_id: 2267670-3
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  • 10
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 13, No. 1 ( 2022-11-04)
    Abstract: The impact of bone cell activation on bacterially-induced osteolysis remains elusive. Here, we show that matrix-embedded osteocytes stimulated with bacterial pathogen-associated molecular patterns (PAMPs) directly drive bone resorption through an MYD88-regulated signaling pathway. Mice lacking MYD88, primarily in osteocytes, protect against osteolysis caused by calvarial injections of bacterial PAMPs and resist alveolar bone resorption induced by oral Porphyromonas gingivalis (Pg ) infection. In contrast, mice with targeted MYD88 restoration in osteocytes exhibit osteolysis with inflammatory cell infiltration. In vitro, bacterial PAMPs induce significantly higher expression of the cytokine RANKL in osteocytes than osteoblasts. Mechanistically, activation of the osteocyte MYD88 pathway up-regulates RANKL by increasing binding of the transcription factors CREB and STAT3 to Rankl enhancers and by suppressing K48-ubiquitination of CREB/CREB binding protein and STAT3. Systemic administration of an MYD88 inhibitor prevents jawbone loss in Pg -driven periodontitis. These findings reveal that osteocytes directly regulate inflammatory osteolysis in bone infection, suggesting that MYD88 and downstream RANKL regulators in osteocytes are therapeutic targets for osteolysis in periodontitis and osteomyelitis.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 2553671-0
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