• 대한치과교정학회지
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• 제26권2호
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• pp.163-174
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• 1996

본 실험은 서로 다른 기전으로 골흡수를 억제한다고 추정되는 약제인 bisphosphonate와 indomethacin을 백서에 투여한 후 교정력을 이용한 치아이동시 약제가 골개조에 미치는 영향을 밝히고자 시행되었다. 동일한 조건에서 사육된 체중 260-300g의 웅성백서(Sprague-Dawley계)를 대조군, bisphosphonate 투여군 및 indomethacin 투여군으로 분류하고 각 군은 다시 장치를 장착한 실험측과 장치를 장착하지 않은 대조측으로 분류하였다. Bisphosphonate(6.3mg/kg,$2.52x10^{-2}mol/L$)와 indomethacin(9mg/kg, $2.52x10^{-2}mol/L$)은 교정장치 장착 6시간 전, 1시간 전 및 24시간 후에 복강내 주사하였으며, 교정력이 가해진 시점으로부터 72시간이 경과한 후 파골세포수를 측정하고 조직학적인 성상을 관찰하였다. 또한 혈액을 채취한 후 혈청 acid phosphatase 및 lactate dehydrogenase 양을 측정하여 다음과 같은 성적을 얻었다. 실험측의 파골세포수는 장치장착 1시간 전에 투여한 bisphosphonate군과 indomethacin군에서 가장 적게 나타났으며, 다른 시간의 약물 투여군은 대조군과 차이가 없었다. 대조측의 파골세포수는 실험측보다 현저히 적게 나타났으며, 대조군 및 약물투여군간에 차이가 없었다. 대조군과 6시간 전 및 24시간 후에 투여한 indomethacin군은 심한 골흡수 양상을 보인 반면, 1시간전 indomethacin군 및 모든 bisphosphonate군에서는 골흡수의 정도가 적었다. 파골세포의 주름변연과 투명대는 대조군 및 indomethacin군에서 가장 뚜렷하게 나타났으며, bisphosphonate 투여군에서는 일부 파골세포들이 무딘 세포돌기만을 내거나 골표면에 부착하지 않고 있는 경우가 많았다. Bisphosphonate와 indomethacin 투여군 모두에서 acid phosphatase 및 lactate dehydrogenase 값이 대조군보다 낮았으며, acid phosphatase 값은 bisphosphonate군이 indomethacin군보다 낮았으나 lactate dehydrogenase 값은 차이가 없었다. 이상의 결과로 bisphosphonate는 파골세포의 수 및 대사활동을 감소시키며 indomethacin은 파골세포의 수를 감소시킴을 알 수 있었다. 또한 두 약물을 비교하면 bisphosphonate는 indomethacin에 비해 골흡수 억제효과가 더 크며 투여시간에 따른 제약도 더 적은 것으로 사료된다.

• 대한치과교정학회지
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• 제19권2호
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• pp.37-55
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• 1989

The tissue reactions concerned in alveolar bone remodelling at the pressure zones of rat molar periodontium associated with the application of force (15 gm) to the maxillary first molar teeth of the albino rats were studied by the transmission electron microscopy. Osteoclasts referrable to bone resorption were observed thereafter 3 hour survival period and undermining resorption was generated thenceforth 2 day survival period. Bone resorption, reversal zone and new bone formation were simultaneously observed adjacent to the zone of undermining resorption in the 7 day survival period. Osteoclasts with well developed primary lysosome, ruffled border, clear zone, granules and Golgi apparatus were detected at the zone of the bone resorption, and dark and bright cells adjacent to the osteoclasts as well. Mononuclear cells and perpendicularly arranged collagenous fibers were observed in the reversal zone and, on the other hand, osteoblasts with well developed Golgi apparatus and rough endoplasmic reticulum were detected at the zone of bone formation.

• 대한의생명과학회지
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• 제23권3호
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• pp.194-200
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• 2017

Bone-resorbing osteoclasts play a major role in maintaining bone homeostasis with bone-forming osteoblasts. Although it has been reported that A2B adenosine receptor (A2BAR) regulates osteoclast differentiation, its effects on apoptosis or proliferation of osteoclasts have been less-defined. Here, we demonstrate that A2BAR stimulation regulates macrophage-colony stimulating factor (M-CSF)-mediated osteoclast proliferation. Stimulation with a specific agonist of A2BAR, BAY 60-6583, significantly reduced M-CSF-mediated osteoclast proliferation in a time- and dose-dependent manner. In addition, A2BAR stimulation induced both apoptosis of the cells and cell arrest in the G1 phase with a decrease of cell number in the G2/M phase. Stimulation with BAY 60-6583 inhibited the activation of Akt by M-CSF, whereas M-CSF-induced ERK1/2 activation was not affected. These results suggest that the inhibition of M-CSF-mediated Akt activation by A2BAR stimulation increases apoptotic response of osteoclasts and induces cell cycle arrest in the G1 phase, thus contributing to the down-regulation of osteoclast proliferation.

• BMB Reports
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• 제50권9호
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• pp.454-459
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• 2017

Tumor suppressor candidate 2 (Tusc2, also known as Fus1) regulates calcium signaling, and $Ca^{2+}$-dependent nuclear factor of activated T-cells (NFAT) and nuclear factor kappa B ($NF-{\kappa}B$) pathways, which play roles in osteoclast differentiation. However, the role of Tusc2 in osteoclasts remains unknown. Here, we report that Tusc2 positively regulates the differentiation of osteoclasts. Overexpression of Tusc2 in osteoclast precursor cells enhanced receptor activator of nuclear factor ${\kappa}B$ ligand (RANKL)-induced osteoclast differentiation. In contrast, small interfering RNA-mediated knockdown of Tusc2 strongly inhibited osteoclast differentiation. In addition, Tusc2 induced the activation of RANKL-mediated $NF-{\kappa}B$ and calcium/calmodulin-dependent kinase IV (CaMKIV)/cAMP-response element (CRE)-binding protein CREB signaling cascades. Taken together, these results suggest that Tusc2 acts as a positive regulator of RANKL-mediated osteoclast differentiation.

• Molecules and Cells
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• 제37권9호
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• pp.685-690
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• 2014

Osteoclasts are large polykaryons that have the unique capacity to degrade bone and are generated by the differentiation of myeloid lineage progenitors. To identify the genes involved in osteoclast development, we performed microarray analysis, and we found that carboxypeptidase E (CPE), a prohormone processing enzyme, was highly upregulated in osteoclasts compared with their precursors, bone marrow-derived macrophages (BMMs). Here, we demonstrate a novel role for CPE in receptor activator of NF-${\kappa}B$ ligand (RANKL)-induced osteoclast differentiation. The overexpression of CPE in BMMs increases the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinuclear osteoclasts and the expression of c-Fos and nuclear factor of activated T cells c1 (NFATc1), which are key regulators in osteoclastogenesis. Furthermore, employing CPE knockout mice, we show that CPE deficiency attenuates osteoclast formation. Together, our data suggest that CPE might be an important modulator of RANKL-induced osteoclast differentiation.

• BMB Reports
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• 제52권8호
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• pp.514-519
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• 2019

Osteoclasts are multinucleated giant cells derived from myeloid progenitors. Excessive bone resorption by osteoclasts can result in serious clinical outcomes for which better treatment options are needed. Here, we identified fibronectin leucine-rich transmembrane protein 2 (Flrt2), a ligand of the Unc5 receptor family for neurons, as a novel target associated with the late/maturation stage of osteoclast differentiation. Flrt2 expression is induced by stimulation with receptor activator of nuclear factor-kB ligand (RANKL). Flrt2 deficiency in osteoclasts results in reduced hyper-multinucleation, which could be restored by RNAi-mediated knockdown of Unc5b. Treatment with Netrin1, another ligand of Unc5b which negatively controls osteoclast multinucleation through down regulation of RANKL-induced Rac1 activation, showed no inhibitory effects on Flrt2-deficient cells. In addition, RANKL-induced Rac1 activation was attenuated in Flrt2-deficient cells. Taken together, these results suggest that Flrt2 regulates osteoclast multinucleation by interfering with Netrin 1-Unc5b interaction and may be a suitable therapeutic target for diseases associated with bone remodeling.

• IMMUNE NETWORK
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• 제19권1호
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• pp.2.1-2.13
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• 2019

The enhanced differentiation and activation of osteoclasts (OCs) in the inflammatory arthritis such as rheumatoid arthritis (RA) and gout causes not only local bone erosion, but also systemic osteoporosis, leading to functional disabilities and morbidity. The induction and amplification of NFATc1, a master regulator of OC differentiation, is mainly regulated by receptor activator of NF-κB (RANK) ligand-RANK and calcium signaling which are amplified in the inflammatory milieu, as well as by inflammatory cytokines such as TNFα, IL-1β and IL-6. Moreover, the predominance of CD4⁺ T cell subsets, which varies depending on the condition of inflammatory diseases, can determine the fate of OC differentiation. Anti-citrullinated peptide antibodies which are critical in the pathogenesis of RA can bind to the citrullinated vimentin on the surface of OC precursors, and in turn promote OC differentiation and function via IL-8. In addition to adaptive immunity, the activation of innate immune system including the nucleotide oligomerization domain leucine rich repeat with a pyrin domain 3 inflammasome and TLRs can regulate OC maturation. The emerging perspectives about the diverse and close interactions between the immune cells and OCs in inflammatory milieu can have a significant impact on the future direction of drug development.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제36권5호
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• pp.386-391
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• 2010

Introduction: Bone resorption is a unique function of osteoclasts. Osteoclasts are a specialized macrophage polykaryon whose differentiation is regulated principally by macrophage colony-stimulating factors, receptor activator of nuclear factor ${\kappa}B$ ligand (RANK) ligand, osteoprotegerin (OPG), and interleukins (IL). Reflecting the integrin-mediated signals, osteoclasts develop a specialized cytoskeleton that allows it to establish an isolated micro-environment between itself and the bone, wherein matrix degradation occurs by a process involving proton transport. The levels of IL-1, IL-6, OPG, and prostaglandin $E_2$ ($PGE_2$) expression were evaluated to study the correlations between dental implant teeth and the adjacent teeth. Materials and Methods: The exudate of the gingival crevice acquired from dental implants, adjacent teeth, opposite teeth and contralateral teeth of 24 patients. Results: 1. The levels of IL-1, IL-6, OPG and $PGE_2$ expression in dental implant teeth were higher than those of the contralateral teeth. 2. IL-1 revealed a higher expression level in the adjacent teeth than in dental implant teeth. 3. The dental implant teeth and adjacent teeth did not show a remarkable difference in the level of IL-1 expression. 4. All the other cytokines were strongly expressed in the dental implant compared to the adjacent teeth. Conclusion: These results suggest that there might be close correlation between dental implant teeth and adjacent teeth in terms of the expressions of cytokines that affect the development and regulation of osteoclasts.

• 한국세라믹학회지
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• 제45권10호
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• pp.618-624
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• 2008

Various calcium phosphate bioceramics are distinguished by their excellent biocompatibility and osteoconductivity. Especially, the exceptional biodegradability of $\beta$-TCP makes it a bone graft substitute of choice in many clinical applications. The activation of osteoclasts, differentiated from macrophage precursor cells, trigger a cell-mediated resorption mechanism that renders $\beta$-TCP biodegradable. Based on this evidence, we studied the biodegradation process of granular-type $\beta$-TCP bone graft substitute through in vitro and in vivo studies. Raw 264.7 cells treated with RANKL and M-CSF differentiated into osteoclasts with macrophage-like properties, as observed with TRAP stain. These osteoclasts were cultured with $\beta$-TCP nano powders synthesized by microwave-assisted process. We confirmed the phagocytosis of osteoclasts by observing $\beta$-TCP particles in their phagosomes via electron microscopy. No damage to the osteoclasts during phagocytosis was observed, nor did the $\beta$-TCP powders show any sign of cytotoxicity. We also observed the histological changes in subcutaneous tissues of rats implanted with granule-type $\beta$-TCP synthesized by fibrous monolithic process. The $\beta$-TCP bone graft substitute was well surrounded with fibrous tissue, and 4 months after implantation, 60% of its mass had been biodegraded. Also, histological findings via H&E stain showed a higher level of infiltration of lymphocytes as well as macrophages around the granule-type $\beta$-TCP. From the results, we have concluded that macrophages play an important role in the biodegradation process of $\beta$-TCP bone graft substitutes.

• 대한약학회:학술대회논문집
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• 대한약학회 2005년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.251-251
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• 2005