TRAP-positive Multinucleated Cells Research Articles

Expression of chondro-osteogenic BMPs in clinical samples of patellar tendinopathy

The pathogenesis of patellar tendinopathy remains unclear. Expression of BMP-2/-4/-7 was reported in an ossified failed tendon healing animal model of patellar tendinopathy. This study aimed to investigate the expression of these chondro-osteogenic BMPs in clinical samples of patellar tendinopathy. Patellar tendon samples were collected from 16 consecutive patients with patellar tendinopathy and 16 consecutive controls undergoing anterior cruciate ligament reconstruction with bone-patellar tendon-bone autograft in the authors' hospital after getting their consent. The expression of BMP-2/-4/-7 was examined in all samples using immunohistochemistry. Ossification observed in two tendinopathy samples was characterized by histology, alizarin red S staining, alcian blue staining, TRAP staining and immunohistochemical staining of Sox9, osteopontin (OPN) and osteocalcin (OCN). Regions of hypo- and hyper-cellularity and vascularity, with loss of crimp structure of collagen matrix, were observed in patellar tendinopathy samples. Round cells and in some cases, cells with typical chondrocyte phenotype were observed. For the ossified tendinopathy samples with positive alizarin red S staining, OPN-positive and Sox9-positive chondrocyte-like cells in alcian blue-stained extracellular matrix, OCN-positive osteoblast-like cells and TRAP-positive multi-nucleated cells were observed around the ossified deposits. No expression of BMP-2/-4/-7 was observed in healthy patellar tendons. However, the expression of BMP-2/-4/-7 was observed in all patellar tendinopathy samples with or without ossification. Clinical samples of patellar tendinopathy showed ectopic expression of BMP-2/-4/-7. This was not evident in control samples from healthy patellar tendons. Prognostic studies, Level III.

Osteoblastic γ-Aminobutyric Acid, Type B Receptors Negatively Regulate Osteoblastogenesis toward Disturbance of Osteoclastogenesis Mediated by Receptor Activator of Nuclear Factor κB Ligand in Mouse Bone

The prevailing view is that signaling machineries for the neurotransmitter GABA are also expressed by cells outside the CNS. In cultured murine calvarial osteoblasts, mRNA was constitutively expressed for both subunits 1 and 2 of metabotropic GABA(B) receptor (GABA(B)R), along with inhibition by the GABA(B)R agonist baclofen of cAMP formation, alkaline phosphatase (ALP) activity, and Ca(2+) accumulation. Moreover, baclofen significantly inhibited the transactivation of receptor activator of nuclear factor-κB ligand (RANKL) gene in a manner sensitive to a GABA(B)R antagonist, in addition to decreasing mRNA expression of bone morphogenetic protein-2 (BMP2), osteocalcin, and osterix. In osteoblastic MC3T3-E1 cells stably transfected with GABA(B)R1 subunit, significant reductions were seen in ALP activity and Ca(2+) accumulation, as well as mRNA expression of osteocalcin, osteopontin, and osterix. In cultured calvarial osteoblasts from GABA(B)R1-null mice exhibiting low bone mineral density in tibia and femur, by contrast, both ALP activity and Ca(2+) accumulation were significantly increased together with promoted expression of both mRNA and proteins for BMP2 and osterix. No significant change was seen in the number of multinucleated cells stained for tartrate-resistant acid phosphatase during the culture of osteoclasts prepared from GABA(B)R1-null mice, whereas a significant increase was seen in the number of tartrate-resistant acid phosphatase-positive multinucleated cells in co-culture of osteoclasts with osteoblasts isolated from GABA(B)R1-null mice. These results suggest that GABA(B)R is predominantly expressed by osteoblasts to negatively regulate osteoblastogenesis through down-regulation of BMP2 expression toward disturbance of osteoclastogenesis after down-regulation of RANKL expression in mouse bone.

Effect of amorphous silica nanoparticles on in vitro RANKL-induced osteoclast differentiation in murine macrophages

Amorphous silica nanoparticles (nSP) have been used as a polishing agent and/or as a remineralization promoter for teeth in the oral care field. The present study investigates the effects of nSP on osteoclast differentiation and the relationship between particle size and these effects. Our results revealed that nSP exerted higher cytotoxicity in macrophage cells compared with submicron-sized silica particles. However, tartrate-resistant acid phosphatase (TRAP) activity and the number of osteoclast cells (TRAP-positive multinucleated cells) were not changed by nSP treatment in the presence of receptor activator of nuclear factor κB ligand (RANKL) at doses that did not induce cytotoxicity by silica particles. These results indicated that nSP did not cause differentiation of osteoclasts. Collectively, the results suggested that nanosilica exerts no effect on RANKL-induced osteoclast differentiation of RAW264.7 cells, although a detailed mechanistic examination of the nSP70-mediated cytotoxic effect is needed.

Inhibition of Osteoclast Differentiation and Bone Resorption by N-Methylpyrrolidone

Regulation of RANKL (receptor activator of nuclear factor κB ligand)-induced osteoclast differentiation is of current interest in the development of antiresorptive agents. Osteoclasts are multinucleated cells that play a crucial role in bone resorption. In this study, we investigated the effects of N-methylpyrrolidone (NMP) on the regulation of RANKL-induced osteoclastogenesis. NMP inhibited RANKL-induced tartrate-resistant acid phosphatase activity and the formation of tartrate-resistant acid phosphatase-positive multinucleated cells. The RANKL-induced expression of NFATc1 (nuclear factor of activated T cells, cytoplasmic 1) and c-Fos, which are key transcription factors for osteoclastogenesis, was also reduced by treatment with NMP. Furthermore, NMP induced disruption of the actin rings and decreased the mRNAs of cathepsin K and MMP-9 (matrix metalloproteinase-9), both involved in bone resorption. Taken together, these results suggest that NMP inhibits osteoclast differentiation and attenuates bone resorption. Therefore, NMP could prove useful for the treatment of osteoporosis or other bone diseases associated with excessive bone resorption.

Plectranthus amboinicus Attenuates Inflammatory Bone Erosion in Mice with Collagen-induced Arthritis by Downregulation of RANKL-induced NFATc1 Expression

Plectranthus amboinicus has been known to treat inflammatory diseases or swelling symptoms. We investigated whether P. amboinicus exhibited an inhibitory effect on osteoclastogenesis in vitro and inflammatory bone erosion in collagen-induced arthritis (CIA) mice, an animal model of rheumatoid arthritis. We attempted to identify the active component of P. amboinicus involved in regulation of osteoclastogenesis. We treated M-CSF- and RANKL-stimulated murine bone marrow-derived macrophages (BMM) and RANKL-induced RAW264.7 cells with different concentrations of P. amboinicus or rosmarinic acid, a phytopolyphenol purified from P. amboinicus, to monitor osteoclast formation by TRAP staining. The mechanism of the inhibition was studied by biochemical analysis such as RT-PCR and immunoblotting. CIA mice were administered gavages of P. amboinicus (375 mg/kg) or placebo. Then clinical, histological, and biochemical measures were assessed to determine the effects of P. amboinicus on synovial inflammation and bone erosion by H&E staining of the inflamed joints and ELISA. Rosmarinic acid strongly inhibited RANKL-induced NF-κB activation and nuclear factor of activated T cells c1 (NFATc1) nuclear translocation in BMM, and also inhibited RANKL-induced formation of TRAP-positive multinucleated cells. A pit formation assay and the CIA animal model showed that P. amboinicus significantly inhibited the bone-resorbing activity of mature osteoclasts. We postulated that rosmarinic acid conferred the inhibitory activity on P. amboinicus for inhibition of osteoclastogenesis via downregulation of RANKL-induced NFATc1 expression. Our results indicated the possibility of P. amboinicus as a new remedy against inflammatory bone destruction.

The inhibitory effect of microRNA-146a expression on bone destruction in collagen-induced arthritis

MicroRNA, a class of noncoding RNA, play a role in human diseases. MicroRNA-146a (miR-146a) is a negative regulator of immune and inflammatory responses, and is strongly expressed in rheumatoid arthritis (RA) synovium and peripheral blood mononuclear cells (PBMCs). This study was undertaken to examine whether miR-146a expression inhibits osteoclastogenesis, and whether administration of miR-146a prevents joint destruction in mice with collagen-induced arthritis (CIA). PBMCs from healthy volunteers were isolated and seeded in culture plates. The following day, double-stranded miR-146a was transfected and cultured in the presence of macrophage colony-stimulating factor and either tumor necrosis factor α or RANKL. After 3 weeks, tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells were counted. Three days after miR-146a culture, the expression of c-Jun, nuclear factor of activated T cells c1 (NF-ATc1), PU.1, and TRAP was evaluated by quantitative reverse transcriptase-polymerase chain reaction. After the onset of distinct arthritis in mice with CIA, double-stranded miR-146a or nonspecific double-stranded RNA was administered twice by intravenous injection. Radiographic and histologic examinations were performed at 4 weeks. The number of TRAP-positive multinucleated cells in human PBMCs was significantly reduced by miR-146a in a dose-dependent manner. The expression of c-Jun, NF-ATc1, PU.1, and TRAP in PBMCs was significantly down-regulated by miR-146a. Administration of miR-146a prevented joint destruction in mice with CIA, although it did not completely ameliorate inflammation. Our findings indicate that expression of miR-146a inhibits osteoclastogenesis and that administration of double-stranded miR-146a prevents joint destruction in arthritic mice. Administration of miR-146a has potential as a novel therapeutic target for bone destruction in RA.

Siglec-15, a member of the sialic acid-binding lectin, is a novel regulator for osteoclast differentiation

Osteoclasts are tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells derived from monocyte/macrophage-lineage precursors and are critically responsible for bone resorption. In giant cell tumor of bone (GCT), numerous TRAP-positive multinucleated giant cells emerge and severe osteolytic bone destruction occurs, implying that the emerged giant cells are biologically similar to osteoclasts. To identify novel genes involved in osteoclastogenesis, we searched genes whose expression pattern was significantly different in GCT from normal and other bone tumor tissues. By screening a human gene expression database, we identified sialic acid-binding immunoglobulin-like lectin 15 (Siglec-15) as one of the genes markedly overexpressed in GCT. The mRNA expression level of Siglec-15 increased in association with osteoclast differentiation in cultures of mouse primary unfractionated bone marrow cells (UBMC), RAW264.7 cells of the mouse macrophage cell line and human osteoclast precursors (OCP). Treatment with polyclonal antibody to mouse Siglec-15 markedly inhibited osteoclast differentiation in primary mouse bone marrow monocyte/macrophage (BMM) cells stimulated with receptor activator of nuclear factor κB ligand (RANKL) or tumor necrosis factor (TNF)-α. The antibody also inhibited osteoclast differentiation in cultures of mouse UBMC and RAW264.7 cells stimulated with active vitamin D3 and RANKL, respectively. Finally, treatment with polyclonal antibody to human Siglec-15 inhibited RANKL-induced TRAP-positive multinuclear cell formation in a human OCP culture. These results suggest that Siglec-15 plays an important role in osteoclast differentiation.

적송잎 추출물이 항산화 활성 및 파골세포의 증식에 미치는 영향

아시아 지역 널리 자생하고 있는 소나무는 항암, 조골세포의 콜라겐 합성 등 다양한 연구결과가 보고된 바 있으나, 항산화 활성에 따른 파골세포의 증식 및 분화에 대한 연구는 미비한 실정이다. 따라서 본 연구에서는 적송잎 추출물별 항산화 활성과 RAW 264.7 세포를 이용하여 적송잎 추출물이 파골세포의 증식과 TRAP 활성에 미치는 영향에 대해 검토하였다. 적송잎 추출물의 총 폴리페놀 함량을 측정한 결과, 열수에탄올 추출물이 140.54 mg/g으로 가장 높은 함량을 나타내었으며, 그 다음은 에탄올 추출물, 열수 추출물, 열수헥산 추출물, 헥산 추출물 순으로 나타났다. SOD 유사활성을 검색한 결과, 열수, 에탄올 및 열수에탄올 추출물이 proanthocyanidin의 47.31%보다 높은 SOD 유사활성을 보였다. MTT assay에 의한 파골세포의 생존율을 측정한 결과, 에탄올 추출물 경우 1 μg/mL의 농도에서 54.04%로 가장 낮은 생존율을 나타내었고 적송잎 헥산 추출물 또한 70% 이하의 생존율을 나타내어, 각 추출물 간의 생존 비율에 차이는 있으나 모든 적송잎 추출물에 있어 파골세포의 성장을 억제하는 결과가 나타났다. 적송잎 추출물의 파골세포 분화 억제 효과를 알아보기 위해 TRAP staining 한 결과, 모든 추출물에서 대조군보다 낮은 TRAP 활성이 나타났다. 특히 열수 및 에탄올 추출물의 경우, 1 μg/mL의 낮은 농도에서 각각 67.8 및 66.3%로 파골세포 분화를 감소시켰으나, 헥산추출물은 약 80%의 분화 감소율을 나타내었다. 100 μg/mL의 고농도 첨가군에서는 오히려 에탄올 추출물의 파골세포분화 감소율이 낮게 나타나, 저농도에서의 효과가 우수한 것으로 나타났다. 따라서 항산화 활성을 가지는 적송잎 추출물이 파골세포의 증식과 분화를 억제하여 골흡수 억제에 효과를 준다는 것이 확인되었으며, 구체적인 기작 연구와 in vivo 연구가 병행된다면 노화 및 골다공증 예방과 관련된 기능성 천연소재로 개발이 가능하리라 사료된다.

Abstract 2148: Thalidomide and liposomal doxorubicin inhibit differentiation and function of human osteoclasts

Abstract Background: Thalidomide inhibits angiogenesis and growth of multiple myeloma. Liposomal doxorubicin is mainly absorbed and degraded by monocyte-macrophage lineage in vivo, implicating a possible targeting effect. Given that osteoclasts (OCs) are derived from precursors of monocyte-macrophage lineage, we hypothesized that thalidomide, liposomal doxorubicin and their combination may affect osteoclastogenesis. Materials and Methods: We isolated CD14+ monocytes from peripheral blood mononuclear cells of healthy subjects and generated OCs under stimulation with macrophage-colony forming factor and receptor activator of NK-κB ligand. Cell viability, surface CD51/61 expression, and tartrate-resistant acid phosphatase (TRAP) activity were assessed by using MTT, flow cytometry and immunohistochemical staining, respectively. Bone resorption activity of OCs was examined. Results: The combination of thalidomide (purchased from TTY Biopharm, Taiwan) and liposomal doxorubicin (purchased from TTY Biopharm, Taiwan) profoundly inhibited the amount of harvested viable OCs. The expression of osteoclast-specific surface antigen CD51/61 was markedly inhibited by each drug and their combination. Specifically, the amount of multinucleated TRAP-positive cells characteristics of OCs and bone resorption activity of OCs were suppressed by each drug and, the mostly, their combination. Conclusion: Thalidomide, liposomal doxorubicin and their combination, beyond currently clinical indications, might be effective regimen to inhibit human osteoclastogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2148. doi:10.1158/1538-7445.AM2011-2148

Resveratrol-mediated SIRT-1 Interactions with p300 Modulate Receptor Activator of NF-κB Ligand (RANKL) Activation of NF-κB Signaling and Inhibit Osteoclastogenesis in Bone-derived Cells

Resveratrol is a polyphenolic phytoestrogen that has been shown to exhibit potent anti-oxidant, anti-inflammatory, and anti-catabolic properties. Increased osteoclastic and decreased osteoblastic activities result in bone resorption and loss of bone mass. These changes have been implicated in pathological processes in rheumatoid arthritis and osteoporosis. Receptor activator of NF-κB ligand (RANKL), a member of the TNF superfamily, is a major mediator of bone loss. In this study, we investigated the effects of resveratrol on RANKL during bone morphogenesis in high density bone cultures in vitro. Untreated bone-derived cell cultures produced well organized bone-like structures with a bone-specific matrix. Treatment with RANKL induced formation of tartrate-resistant acid phosphatase-positive multinucleated cells that exhibited morphological features of osteoclasts. RANKL induced NF-κB activation, whereas pretreatment with resveratrol completely inhibited this activation and suppressed the activation of IκBα kinase and IκBα phosphorylation and degradation. RANKL up-regulated p300 (a histone acetyltransferase) expression, which, in turn, promoted acetylation of NF-κB. Resveratrol inhibited RANKL-induced acetylation and nuclear translocation of NF-κB in a time- and concentration-dependent manner. In addition, activation of Sirt-1 (a histone deacetylase) by resveratrol induced Sirt-1-p300 association in bone-derived and preosteoblastic cells, leading to deacetylation of RANKL-induced NF-κB, inhibition of NF-κB transcriptional activation, and osteoclastogenesis. Co-treatment with resveratrol activated the bone transcription factors Cbfa-1 and Sirt-1 and induced the formation of Sirt-1-Cbfa-1 complexes. Overall, these results demonstrate that resveratrol-activated Sirt-1 plays pivotal roles in regulating the balance between the osteoclastic versus osteoblastic activity result in bone formation in vitro thereby highlighting its therapeutic potential for treating osteoporosis and rheumatoid arthritis-related bone loss.

IL-22 promotes osteoclastogenesis in rheumatoid arthritis through induction of RANKL from synovial fibroblasts (117.25)

Abstract This study aims to determine the regulatory role of interleukin(IL)-22 on the expression of receptor activator of NF-kB ligand(RANKL) and the induction of osteoclastogenesis in rheumatoid arthritis(RA). The concentrations of IL-22 and RANKL in sera and synovial fluids(SF)of RA patients were measured by ELISA. After RA synovial fibroblasts were treated with rhIL-22, the expression of RANKL mRNA and protein was determined using real-time PCR,western blot,and immunostaining.Human monocytes were cocultured with IL-22-prestimulated RA synovial fibroblasts and monocyte-colony stimulating factor(M-CSF), and then osteoclastogenesis was determined by counting of TRAP-positive multinucleated cells. Serum and SF IL-22 concentration in RA patients was higher than in osteoarthritis patients and healthy subjects. When RA synovial fibroblasts were treated with rhIL-22, the expression of RANKL mRNA and protein was upregulated in a dose-dependent manner. The IL-22-induced RANKL expression was significantly down-regulated by inhibition of p38 MAPK/NF-kB and JAK-2/STAT3. When human monocytes were cultured with IL-22-prestimulated RA synovial fibroblasts in the absence of RANKL, the monocytes were differentiated into osteoclasts, which was blocked by the inhibition of p38 MAPK/NF-kB and JAK-2/STAT3.Our results suggest that IL-22 up-reugulates RANKL expression in RA synovial fibroblasts and it also promotes osteoclastogenesis, which are mediated by p38 MAPK/NF-kB and JAK-2/STAT3 pathways.

The Role of iNOS and PHOX in Periapical Bone Resorption

Nitric oxide (NO) and reactive oxygen species (ROS) are key molecules in resistance to pathogens. Little is known about their role in pathogenesis of periapical lesions. To address this issue, we induced periapical lesions in mice lacking nitric oxide synthase (iNOS-/-) or phagocyte oxidase (PHOX-/-). iNOS-/- mice expressed higher levels of IL-1β, TNF-α, RANK, RANKL, and MCP-1 than C57BL/6 and PHOX-/-. Apical thickening of the periodontal ligament was also greater in iNOS-/- compared with other groups. Interestingly, ROS production did not interfere in periapical lesion progression, but seemed to be essential for the appearance of multinucleated TRAP-positive cells. Thus, periapical lesion progression in iNOS-/- was associated with an imbalance of pro-inflammatory cytokines (IL-1β and TNF-α), bone-resorptive modulators (RANK and RANKL), and MCP-1. We conclude that NO, but not ROS, controls progression of bone resorption in a murine experimental model of apical periodontitis.

S100A8 enhances osteoclast-mediated bone resorption in experimental antigen-induced arthritis through activation of toll-like receptor 4

ObjectiveRheumatoid arthritis (RA) is characterised by severe bone erosions caused by enhanced osteoclast formation and activity. Significantly elevated S100A8 and S100A9 levels in serum and synovial fluid of RA patients...

Role of the A20-TRAF6 Axis in Lipopolysaccharide-mediated Osteoclastogenesis

Bacterial lipopolysaccharide (LPS) has long been suggested as a potent inducer of bone loss in vivo despite controversial effects on osteoclast precursors. Recently, the role of the deubiquitinating protease A20 in regulating the LPS response in various organs was reported. In the present study, we investigated whether A20 is expressed in osteoclast cultures in response to RANKL or LPS and whether this protein plays a role in osteoclast formation and activation. Human peripheral blood mononuclear cells were cultured in the presence of M-CSF ± RANKL ± LPS. Although LPS induced the formation of multinucleated TRAP-positive cells expressing OSCAR, cathepsin K, and the calcitonin receptor, these cells were not capable of lacunar resorption. Release of TNF-α was noted in LPS-treated cultures, and the addition of a neutralizing anti-TNF-α antibody abrogated osteoclast formation in these cultures. A20 appeared to be a late-expressed gene in LPS-treated cultures and was associated with TRAF6 degradation and NF-κB inhibition. Silencing of A20 restored TRAF6 expression and NF-κB activation and resulted in increased bone resorption in LPS-treated cultures. A20 appeared important in the control of bone resorption and could represent a therapeutic target to treat patients with bone resorption associated with inflammatory diseases.

Acid sphingomyelinase regulates osteoclastogenesis by modulating sphingosine kinases downstream of RANKL signaling

Acid sphingomyelinase (ASM) was identified as a gene induced by NFAT2 activation in osteoclasts. Suppression of ASM expression in bone marrow macrophages by knockdown enhanced c-Fos/NFAT2 expression, increasing the number of TRAP-positive multinucleated cells in vitro. SphK1 was upregulated during the late stage of osteoclastogenesis, while SphK2 expression remained constant. SphK1 was downregulated following ASM knockdown, while SphK2 levels were unchanged. Experiments using shRNA and catalytically-inactive form demonstrated inhibitory and stimulatory activities on osteoclast formation of SphK1 and SphK2, respectively. These results suggest that ASM regulates osteoclastogenesis by modulating the balance between SphK1 and SphK2 downstream of RANKL signaling.

Age-dependent changes in osteoclast formation in a new strain of P2X7 receptor knockout mice

Event Abstract Back to Event Age-dependent changes in osteoclast formation in a new strain of P2X7 receptor knockout mice A Agrawal1*, S Syberg2, NR Jørgensen2 and A Gartland1 1 the University of Sheffield, Department of Human Metabolism, United Kingdom 2 University Hospital of Copenhagen Glostrup, Research Center for Ageing and Osteoporosis and Dept of Clinical Chemistry, Denmark The P2X7 receptor (P2X7R) is an ion-gated channel belonging to the family of purinergic receptors that get activated by extracellular nucleotides. The role of the P2X7R in regulating osteoclastogenesis has been described using knockout mice as well as primary human osteoclast cultures. These studies have contradictory findings as blocking the receptor in vitro prevented fusion of human monocytes to form multinucleated osteoclasts, whilst two different models of knockout mice retained the ability to form multinucleated osteoclasts in vivo and in vitro. The mice used in these studies have a natural mutation in the gene coding for P2X7R leading to reduced receptor function. Therefore, we generated mice with no known mutation in the P2X7R to better determine its role in the process of osteoclastogenesis. Spleens from age-matched WT and KO BALB/c mice were removed and the mononuclear fraction isolated. Equal numbers of cells were seeded onto glass coverslips or dentine discs and cultured in the presence of M-CSF and RANKL. Cells on glass coverslips were cultured for 7 days and TRAP stained to assess the number of multinucleated osteoclasts. Dentine discs were stained after 9 days to assess resorption. KO mice had a significantly higher number of multinucleated, TRAP positive cells and increased resorption compared to WT controls at 3 months of age. Mature, 6 month old, KO mice had a higher number of multinucleated TRAP positive cells, however, the resorption was the same in KO and WT cultures. These data suggest that receptor deletion has a role in enhancing osteoclast formation and subsequently function in young and developing mice. In older mice whilst there was an increase in osteoclast formation and activity in both WT and KO mice compared to 3 months of age, the higher number of osteoclasts observed in KO mice did not lead to a significantly higher amount of resorption compared to WT. We therefore propose the P2X7-/- BALB/c mice as a new model for studying the role of P2X7 receptor and that P2X7R in these mice enhances the differentiation and survival of osteoclasts but reduces their resorptive activity with increasing age. Keywords: Bones, Bone Research Conference: 2011 joint meeting of the Bone Research Society & the British Orthopaedic Research Society, Cambridge, United Kingdom, 27 Jun - 29 Jun, 2011. Presentation Type: Poster Topic: Abstracts Citation: Agrawal A, Syberg S, Jørgensen N and Gartland A (2011). Age-dependent changes in osteoclast formation in a new strain of P2X7 receptor knockout mice. Front. Endocrinol. Conference Abstract: 2011 joint meeting of the Bone Research Society & the British Orthopaedic Research Society. doi: 10.3389/conf.fendo.2011.02.00001 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Sep 2011; Published Online: 30 Sep 2011. * Correspondence: Prof. A Agrawal, the University of Sheffield, Department of Human Metabolism, Sheffield, S10 2RX, United Kingdom, a.gartland@sheffield.ac.uk Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers A Agrawal S Syberg NR Jørgensen A Gartland Google A Agrawal S Syberg NR Jørgensen A Gartland Google Scholar A Agrawal S Syberg NR Jørgensen A Gartland PubMed A Agrawal S Syberg NR Jørgensen A Gartland Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Interleukin-6 and soluble interleukin-6 receptor suppress osteoclastic differentiation by inducing PGE2 production in chondrocytes

This study examined how interleukin-6 (IL-6) and soluble IL-6 receptor (sIL-6r) influence osteoclastic differentiation through the function of chondrocytes. Chondrocytes were cultured with or without IL-6 and/or sIL-6r in the presence or absence of NS398, a specific inhibitor of cyclooxygenase (COX)-2, for up to 28 days. Chondrocytes were also cultured with or without IL-6 and sIL-6r for 28 days, and the conditioned medium from cells cultured without IL-6 and sIL-6r was used to induce differentiation of RAW264.7 cells into osteoclast precursors. Osteoclastic differentiation was assessed by tartrate-resistant acid phosphatase (TRAP) staining. Expression of osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL), COX-2, and prostaglandin E(2) (PGE(2)) increased in cells exposed to IL-6 and sIL-6r, whereas expression of macrophage colony-stimulating factor (M-CSF) and bone resorption-related enzymes decreased. NS398 blocked the stimulatory/suppressive effects of IL-6 and sIL-6r on the expression of OPG, RANKL, and M-CSF. Fewer TRAP-positive multinucleated cells were detected after treatment with conditioned medium from IL-6- and sIL-6r-treated chondrocytes than after treatment with conditioned medium from untreated chondrocytes. These results suggest that IL-6 and sIL-6r interfere with osteoclast function through the involvement of chondrocytes. Specifically, they appear to suppress the differentiation of osteoclast precursors into osteoclasts by inducing chondrocytic PGE(2) production, which, in turn, increases OPG secretion and decreases M-CSF secretion by chondrocytes.

Difference between dogs and rats with regard to osteoclast‐like cells in calcium‐deficient hydroxyapatite‐induced osteoinduction

Material-induced osteoinduction is reported in comparatively large animals such as dogs and pigs; however, it does not often occur in small animals such as rodents. In this study, we implanted porous calcium-deficient hydroxyapatite (CDHA) in the dorsal muscles of dogs and rats and compared the two species, with emphasis on multinucleated cells, by using hematoxylin and eosin (HE) staining, tartrate-resistant acid phosphatase (TRAP) staining, transmission electron microscope (TEM) observation, and reverse transcription-polymerase chain reaction (RT-PCR). In CDHA extracted from dogs, numerous TRAP-positive multinucleated cells were detected after 2 weeks and new bone formation was observed after 4 weeks. In contrast, in rats, only a small number of TRAP-positive cells were detected and no bone formation was observed within 6 weeks. CDHA was more degraded in dogs than in rats. TEM observation of the multinucleated cells in CDHA extracted from dogs after 3 weeks revealed osteoclast-like features such as ruffled borders. However, CDHA extracted from rats did not exhibit osteoclast-like features. RT-PCR evaluation showed that the expression of cathepsin K was higher in dogs than in rats. These results indicate that TRAP-positive cells might be one of the main factors responsible for the cross-species difference in material-induced osteoinduction.

Mechanisms involved in the inhibition of osteoclast generation by the benzothiophene SERM LY117018

Selective estrogen receptor modulators are compounds that act via estrogen receptors in different tissues to mediate either estrogenic or estrogen antagonistic effects in osteoporosis patients. The aim of this study was to assess the effect of the selective estrogen receptor modulator LY117018, a raloxifene analogue, on osteoclastogenesis in vitro. In primary murine bone marrow cultures osteoclasts, defined as TRAP-positive multinucleated cells, were induced by 10(-8) M 1,25-dihydroxyvitamin D(3). LY117018 at concentrations between 10(-12) M and 10(-9) M significantly reduced the number of osteoclasts. At higher concentrations no effect of LY117018 on osteoclast generation was observed. LY117018 enhanced alkaline phosphatase activity of mouse calvaria osteoblasts at a concentration of 10(-14) to 10(-7) M, but had no influence on the proliferation and transcription of RANKL and osteoprotegerin. In order to study the effect of the compound on the production of cytokines that can stimulate bone resorption, spleen cells were incubated with LY117018. Data from four-color flow cytometric analysis indicate a significantly decreased frequency of tumor necrosis factor-α positive CD8(+) cells after treatment with LY117018. These findings suggest that LY117018 can significantly inhibit the generation of osteoclasts and stimulate osteogenic differentiation in vitro. Suppression of tumor necrosis factor-α production by LY117018 may contribute to its anti-osteoclastogenic effect.

Interleukin-17A induces cathepsin K and MMP-9 expression in osteoclasts via celecoxib-blocked prostaglandin E 2 in osteoblasts

Interleukin-17 (IL-17) is a cytokine secreted primarily by T H-17 cells that can stimulate the development of osteoclasts (osteoclastogenesis) in the presence of osteoblasts. IL-17, through osteoblasts, has indirect effects on the expression of bone resorption-related enzymes in osteoclasts, which have not been well clarified. Here, using MC3T3-E1 cells and RAW264.7 cells as osteoblasts and osteoclast precursors, we aimed to clarify these effects of IL-17A. MC3T3-E1 cells were cultured in the presence or absence of IL-17A for 72 h and the conditioned media collected (in the presence of soluble receptor activator of NF-кB ligand) and used to culture RAW264.7 cells. To assess osteoclast differentiation, adherent cells were fixed and stained for tartrate-resistant acid phosphatase (TRAP). Our analyses demonstrated that the number of TRAP-positive multinucleated cells increases after 3 days of culture in conditioned medium from IL-17A-treated cells compared to untreated controls. In addition, we observed that the levels of cathepsin K and MMP-9 increase in the conditioned medium from IL-17A-treated cells, whereas CA II expression levels remain unaffected. PGE 2 production from MC3T3-E1 cells increased in the presence of IL-17A. Celecoxib, a specific inhibitor of cyclooxygenase-2 (COX-2), blocked both the IL-17A-stimulated increase in TRAP-positive multinucleated cells and the expression of cathepsin K and MMP-9. Furthermore, when MC3T3-E1 cells were transformed with small interfering RNA to silence COX-2 expression before IL-17A treatment, the resulting conditioned medium was less effective at inducing cathepsin K and MMP-9 expression in RAW264.7 cells. These results suggest that IL-17A induces the differentiation and function of osteoclasts via celecoxib-blocked prostaglandin, mainly PGE 2, in osteoblasts.