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Role of interleukin-6 on RANKL-RANK/osteoprotegerin system in hypothyroid ovariectomized mice. Folia Histochem Cytobiol 2011; 48:549-54. [PMID: 21478097 DOI: 10.2478/v10042-010-0064-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Postmenopausal women frequently develop hypothyroidism. Estrogen depletion is accompanied by an increase of IL-6, accelerating bone turnover. The influence of hypothyroidism on bone metabolism in postmenopausal women is poorly understood. The aim of the study was an attempt to clarify the role of interleukin-6 on RANKL-RANK/osteoprotegerin system in hypothyroid ovariectomized mice. The study was performed on 56, 12-13 weeks old, female mice: C57BL/6J (wild-type; WT) and C57BL/6JIL6-/-Kopf (IL-6 knock-out; IL6KO). The mice were randomly divided into 8 groups with 7 mice in each one: 1/ WT controls, 2/ IL6KO controls, 3/ WT hypothyroid mice, 4/ IL6KO hypothyroid mice, 5/ WT ovariectomized, 6/ IL6KO ovariectomized, 7/ WT ovariectomized hypothyroid mice and 8/ IL6KO ovariectomized hypothyroid mice. Experimental model of menopause was produced by bilateral ovariectomy carried out in 8-9 weeks old mice. Experimental model of hypothyroidism was induced by propylthiouracyl administration in driking water. The serum levels of TRACP 5b, osteocalcin, OPG and RANKL were determined by ELISA. Serum RANKL concentrations were elevated significantly in all groups of ovariectomized mice as compared to respective controls, but in a minor degree in IL6KO hypothyroid mice as compared to wild-type animals. Moreover sRANKL values were significantly lower in IL6KO as compared to WT controls and IL6KO PTU injected mice. Osteoprotegerin serum levels were decreased in all IL-6 deficient mice and in a highest degree in sham-operated hypothyroid mice. To sum up, the results of the present study suggest that estrogens deficit is a strong stimulus for RANKL-RANK/OPG pathway that breaks an inhibitory influence of hypothyroidism even in IL-6 deficient mice.
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Abstract
SummaryThe essential polyunsaturated fatty acids (PUFAs) are divided into two classes, n-3 (ω-3) and n-6 (ω-6) and their dietary precursors are α-linolenic (ALA) and linoleic acid (LA), respectively. PUFAs are precursors of a wide range of metabolites, for example eicosanoids like prostaglandins and leukotrienes, which play critical roles in the regulation of a variety of biological processes, including bone metabolism.A large body of evidence supports an effect of PUFA on bone metabolism which may be mediated by regulation of osteoblastogenesis and osteoclast activity, change of membrane function, decrease in inflammatory cytokines, such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumour necrosis factor alpha (TNF-α), modulation of peroxisome proliferators-activated receptor γ (PPARγ) and influence in NO secretion and NO synthase.Animal studies have shown that a higher dietary omega-3/omega-6 fatty acids ratio is associated with beneficial effects on bone health. Human studies conducted in elderly subjects suggest that omega-3 instead of omega-6 has a positive effect on bone metabolism. In spite of increasing evidence, studies conducted in humans do not allow us to draw a definitive conclusion on the usefulness of PUFAs in clinical practice.
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Kruger M, Coetzee M, Haag M, Weiler H. Long-chain polyunsaturated fatty acids: Selected mechanisms of action on bone. Prog Lipid Res 2010; 49:438-49. [DOI: 10.1016/j.plipres.2010.06.002] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Indexed: 01/11/2023]
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The balance between soluble receptors regulating IL-6 trans-signaling is predictive for the RANKL/osteoprotegerin ratio in postmenopausal women with rheumatoid arthritis. Rheumatol Int 2010; 32:199-206. [DOI: 10.1007/s00296-010-1606-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 08/23/2010] [Indexed: 10/19/2022]
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Jurado S, Garcia-Giralt N, Díez-Pérez A, Esbrit P, Yoskovitz G, Agueda L, Urreizti R, Pérez-Edo L, Saló G, Mellibovsky L, Balcells S, Grinberg D, Nogués X. Effect of IL-1beta, PGE(2), and TGF-beta1 on the expression of OPG and RANKL in normal and osteoporotic primary human osteoblasts. J Cell Biochem 2010; 110:304-10. [PMID: 20225238 DOI: 10.1002/jcb.22538] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The RANKL/RANK/OPG pathway is essential for bone remodeling regulation. Many hormones and cytokines are involved in regulating gene expression in most of the pathway components. Moreover, any deregulation of this pathway can alter bone metabolism, resulting in loss or gain of bone mass. Whether osteoblasts from osteoporotic and nonosteoporotic patients respond differently to cytokines is unknown. The aim of this study was to compare the effect of interleukin (IL)-1beta, proftaglandin E(2) (PGE(2)), and transforming growth factor-beta1 (TGF-beta1) treatments on OPG and RANKL gene expression in normal (n = 11) and osteoporotic (n = 8) primary osteoblasts. OPG and RANKL mRNA levels of primary human osteoblastic (hOB) cell cultures were assessed by real-time PCR. In all cultures, OPG mRNA increased significantly in response to IL-1beta treatment and decreased in response to TGF-beta1 whereas PGE(2) treatment had no effect. RANKL mRNA levels were significantly increased by all treatments. Differences in OPG and RANKL responses were observed between osteoporotic and nonosteoporotic hOB: in osteoporotic hOB, the OPG response to IL-1beta treatment was up to three times lower (P = 0.009), whereas that of RANKL response to TGF-beta1 was five times higher (P = 0.002) after 8 h of treatment, as compared with those in nonosteoporotic hOBs. In conclusion, osteoporotic hOB cells showed an anomalous response under cytokine stimulation, consistent with an enhanced osteoclastogenesis resulting in high levels of bone resorption.
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Affiliation(s)
- Susana Jurado
- Internal Medicine, URFOA, IMIM, RETICEF, Hospital del Mar, Autonomous University of Barcelona, Barcelona, Spain.
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Jones MD, Tran CW, Li G, Maksymowych WP, Zernicke RF, Doschak MR. In vivo microfocal computed tomography and micro-magnetic resonance imaging evaluation of antiresorptive and antiinflammatory drugs as preventive treatments of osteoarthritis in the rat. ACTA ACUST UNITED AC 2010; 62:2726-35. [DOI: 10.1002/art.27595] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Lau E, Al-Dujaili S, Guenther A, Liu D, Wang L, You L. Effect of low-magnitude, high-frequency vibration on osteocytes in the regulation of osteoclasts. Bone 2010; 46:1508-15. [PMID: 20211285 PMCID: PMC3084034 DOI: 10.1016/j.bone.2010.02.031] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 01/15/2010] [Accepted: 02/26/2010] [Indexed: 12/26/2022]
Abstract
Osteocytes are well evidenced to be the major mechanosensor in bone, responsible for sending signals to the effector cells (osteoblasts and osteoclasts) that carry out bone formation and resorption. Consistent with this hypothesis, it has been shown that osteocytes release various soluble factors (e.g. transforming growth factor-beta, nitric oxide, and prostaglandins) that influence osteoblastic and osteoclastic activities when subjected to a variety of mechanical stimuli, including fluid flow, hydrostatic pressure, and mechanical stretching. Recently, low-magnitude, high-frequency (LMHF) vibration (e.g., acceleration less than <1 x g, where g=9.81m/s(2), at 20-90 Hz) has gained much interest as studies have shown that such mechanical stimulation can positively influence skeletal homeostasis in animals and humans. Although the anabolic and anti-resorptive potential of LMHF vibration is becoming apparent, the signaling pathways that mediate bone adaptation to LMHF vibration are unknown. We hypothesize that osteocytes are the mechanosensor responsible for detecting the vibration stimulation and producing soluble factors that modulate the activity of effector cells. Hence, we applied low-magnitude (0.3 x g) vibrations to osteocyte-like MLO-Y4 cells at various frequencies (30, 60, 90 Hz) for 1h. We found that osteocytes were sensitive to this vibration stimulus at the transcriptional level: COX-2 maximally increased by 344% at 90Hz, while RANKL decreased most significantly (-55%, p<0.01) at 60Hz. Conditioned medium collected from the vibrated MLO-Y4 cells attenuated the formation of large osteoclasts (> or =10 nuclei) by 36% (p<0.05) and the amount of osteoclastic resorption by 20% (p=0.07). The amount of soluble RANKL (sRANKL) in the conditioned medium was found to be 53% lower in the vibrated group (p<0.01), while PGE(2) release was also significantly decreased (-61%, p<0.01). We conclude that osteocytes are able to sense LMHF vibration and respond by producing soluble factors that inhibit osteoclast formation.
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Affiliation(s)
- Esther Lau
- Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Saja Al-Dujaili
- Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Axel Guenther
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
| | - Dawei Liu
- Department of Developmental Sciences/Orthodontics, Marquette University School of Dentistry, Milwaukee, WI, USA
| | - Liyun Wang
- Center for Biomedical Engineering Research, Department of Mechanical Engineering, University of Delaware, Newark, DE, USA
| | - Lidan You
- Institute of Biomaterials & Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, ON, Canada
- Corresponding author: 5 King's College Road, Room 314D, Toronto, Ontario, Canada M5S 3G8, Tel: 416-978-5736 Fax: 416-978-7753,
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Kowalska M, Druzd-Sitek A, Fuksiewicz M, Kotowicz B, Chechlinska M, Syczewska M, Walewski J, Kaminska J. Procollagen I amino-terminal propeptide as a potential marker for multiple myeloma. Clin Biochem 2010; 43:604-8. [DOI: 10.1016/j.clinbiochem.2009.12.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 12/16/2009] [Accepted: 12/17/2009] [Indexed: 10/20/2022]
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Wang Y, Grainger DW. siRNA knock-down of RANK signaling to control osteoclast-mediated bone resorption. Pharm Res 2010; 27:1273-84. [PMID: 20333451 DOI: 10.1007/s11095-010-0099-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 02/19/2010] [Indexed: 12/21/2022]
Abstract
PURPOSE To demonstrate the ability of small interfering (si)RNA targeting the cell receptor, RANK, to control osteoclast function in cultures of both primary and secondary osteoclasts and their precursor cells. METHODS siRNA targeting RANK was transfected into both RAW264.7 and primary bone marrow cell cultures. RANK knock-down by siRNA and functional inhibition were assessed in both mature osteoclast and their precursor cell cultures. RANK mRNA message and protein expression after the transfections were analyzed by PCR and Western blot, respectively. Off-target effects were assessed. The inhibition of osteoclast formation was evaluated using tartrate-resistant acid phosphatase (TRAP) assay, and subsequent bone resorption was determined by resorption pit assay. RESULTS Both osteoclasts and osteoclast precursors can be targeted by siRNA in serum-containing media. Delivery of siRNA targeting RANK to both RAW 264.7 and primary bone marrow cell cultures produces short term repression of RANK expression without off-targeting effects, and significantly inhibits both osteoclast formation and bone resorption. Moreover, data support successful RANK knock-down by siRNA specifically in mature osteoclast cultures. CONCLUSIONS RANK is demonstrated to be an attractive target for siRNA control of osteoclast activity, with utility for development of new therapeutics for low bone mass pathologies or osteoporosis.
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Affiliation(s)
- Yuwei Wang
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah 84112-5820, USA.
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60
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Moreno-Rubio J, Herrero-Beaumont G, Tardı´o L, álvarez-Soria MÁ, Largo R. Nonsteroidal antiinflammatory drugs and prostaglandin E2modulate the synthesis of osteoprotegerin and RANKL in the cartilage of patients with severe knee osteoarthritis. ACTA ACUST UNITED AC 2010; 62:478-88. [DOI: 10.1002/art.27204] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Lee CM, Genetos DC, Wong A, Yellowley CE. Prostaglandin expression profile in hypoxic osteoblastic cells. J Bone Miner Metab 2010; 28:8-16. [PMID: 19471853 DOI: 10.1007/s00774-009-0096-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 04/09/2009] [Indexed: 11/28/2022]
Abstract
Conditions such as fracture and unloading have been shown to be associated with tissue and cellular hypoxia in bone. The effects of hypoxia on bone cell physiology and ultimately its impact on bone tissue repair and remodeling are not well understood. In this study, we investigated the role of hypoxia on prostaglandin release from osteoblastic cells cultured in 2% (hypoxia), 5% (potentially cellular normoxia), and 21% (normoxia for standard cell culture conditions) oxygen for up to 24 h. We quantified the effects of reduced oxygen tension on the release of prostaglandin (PG)E(2), PGF(2alpha), PGD(2), and PGI(2). The mechanism by which hypoxia increases PG production was investigated by examining the various regulatory components of the PG biosynthetic pathway. Our data show that PGE(2) levels alone are significantly elevated under hypoxic conditions. Also, we show that cyclooxygenase (COX)-1 and COX-2 play an important role in hypoxia-induced PGE(2) production, possibly via a mechanism involving changes in their respective activity levels under low oxygen conditions. The effect of hypoxia on PGE(2) levels was mimicked by dimethyloxaloglycine, a known activator of the HIF pathway. In addition, we confirmed that HIF-1alpha was stabilized in osteoblastic cells under hypoxia. Taken together these data suggest a role for the HIF pathway in regulation of PGE(2) levels under hypoxic conditions. Previous studies have detected release of prostaglandins from areas of damaged bone, such as a fracture site, and our data may contribute to an understanding of how this release is regulated.
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Affiliation(s)
- Christina M Lee
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California Davis, 1321 Haring Hall, One Shields Ave, Davis, CA 95616, USA
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Abstract
Periprosthetic osteolysis is the most common cause of aseptic loosening in total joint arthroplasty. The role of inflammatory mediators such as prostaglandin E2 (PGE2) and osteoclast promoting factors including RANKL in the pathogenesis of osteolysis has been well characterized. However, the PGE2 receptor (EP1, EP2, or EP4), and cell type in which it is expressed, which is responsible for PGE2 induction of RANKL during wear debris-induced osteolysis, has yet to be elucidated. To address this, we used mice genetically deficient in these EP receptors to assess PGE2 and wear debris responses in vitro and in vivo. Wear debris-induced osteolysis and RANKL expression were observed at similar levels in WT, EP1(-/-), and EP2(-/-) mice, indicating that these receptors do not mediate PGE2 signals in this process. A conditional knockout approach was used to eliminate EP4 expression in FSP1(+) fibroblasts that are the predominant source of RANKL. In the absence of EP4, fibroblasts do not express RANKL after stimulation with particles or PGE2, nor do they exhibit high levels of osteoclasts and osteolysis. These results show that periprosthetic fibroblasts are important mediators of osteolysis through the expression of RANKL, which is induced after PGE2 signaling through the EP4 receptor.
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63
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Sanchez C, Gabay O, Salvat C, Henrotin YE, Berenbaum F. Mechanical loading highly increases IL-6 production and decreases OPG expression by osteoblasts. Osteoarthritis Cartilage 2009; 17:473-81. [PMID: 18974013 DOI: 10.1016/j.joca.2008.09.007] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Accepted: 09/12/2008] [Indexed: 02/02/2023]
Abstract
OBJECTIVES In osteoarthritis (OA), mechanical factors play a key role, not only in cartilage degradation, but also in subchondral bone sclerosis. The aim of this study was to develop on original compression model for studying the effect of mechanical stress on osteoblasts. MATERIALS AND METHODS We investigate the effects of compression on primary calvaria osteoblasts isolated from newborn mice and cultured for 28 days in monolayer. At the end of this period, osteoblasts were embedded in a newly synthesized extracellular matrix which formed a three-dimensional membrane. This membrane was then submitted to compression in Biopress Flexercell plates (1-1.7 MPa compressions at 1 Hz frequency) during 1-8h. The expression of 20 genes was investigated by real time reverse transcriptase polymerase chain reaction. Interleukin (IL)-6, matrix metalloproteinase (MMP)-3 and prostaglandin (PG)E(2) were assayed in the culture medium by specific immunoassays. RESULTS The compression highly increased IL-6 and cyclooxygenase (COX)-2 mRNA levels in osteoblasts. In parallel, increased amount of IL-6 and PGE(2) was found in the supernatant of loaded osteoblasts. This stimulation reached a maximum after 4h of 10% compression. MMP-2, MMP-3, and MMP-13 mRNA levels were also increased by compressive stress, while 15-hydroxyprostaglandin-dehydrogenase and osteoprotegerin (OPG) start to decrease at hour 4. COX-1, microsomial PG E synthase-1 (mPGES1), mPGES2 and cytosolic PGES and receptor activator of nuclear factor ligand (RANKL) were unmodified. Finally, we observed that alpha 5 beta 1 integrin, intracellular Ca(++), nuclear factor-kappaB and extracellular signal-regulated kinase 1/2 pathways were involved in the compression-induced IL-6 and PGE(2) production. IL-6 neutralizing antibodies and piroxicam inhibited the decrease OPG expression, but did not modify RANKL mRNA level, indicating that IL-6 and PGE(2) induce a decrease of the OPG/RANKL ratio. CONCLUSION This work demonstrates that IL-6 is mechano-sensitive cytokine and probably a key factor in the biomechanical control of bone remodeling in OA.
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Affiliation(s)
- C Sanchez
- Bone and Cartilage Metabolism Research Unit, University of Liège, Belgium
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Capulli M, Rufo A, Teti A, Rucci N. Global transcriptome analysis in mouse calvarial osteoblasts highlights sets of genes regulated by modeled microgravity and identifies a “mechanoresponsive osteoblast gene signature”. J Cell Biochem 2009; 107:240-52. [DOI: 10.1002/jcb.22120] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Downey ME, Holliday LS, Aguirre JI, Wronski TJ. In vitro and in vivo evidence for stimulation of bone resorption by an EP4 receptor agonist and basic fibroblast growth factor: Implications for their efficacy as bone anabolic agents. Bone 2009; 44:266-74. [PMID: 19013265 PMCID: PMC2663525 DOI: 10.1016/j.bone.2008.10.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2008] [Revised: 09/01/2008] [Accepted: 10/08/2008] [Indexed: 11/27/2022]
Abstract
Prostaglandin E2 receptor subtype 4 agonists (EP4A) and basic fibroblast growth factor (FGF2) stimulate bone formation, but their effects on bone resorption are controversial. To provide additional insight into the skeletal effects of EP4A and FGF2, their regulation of expression of genes associated with bone formation and resorption in aged ovariectomized (OVX) rats and in cultured mouse bone marrow cells was determined. RNA was isolated from lumbar vertebrae of OVX rats (16 months of age) treated daily for 3 weeks with FGF2 or EP4A and processed for quantitative real time-PCR analyses. mRNA expression for the receptor activator of NF-kappaB ligand (RANKL) and cathepsin K (CTSK), but not osteoprotegerin (OPG), were upregulated by both FGF2 and EP4A. Addition of FGF2 and EP4A to the medium of cultured mouse bone marrow cells increased the formation of tartrate resistant acid phosphatase (TRAP) positive cells, upregulated the expression of RANKL and CTSK, and downregulated expression for OPG. EP4A also increased the formation of actin rings, an indicator of osteoclast activation, in a dose dependent manner in osteoclasts cultured on bone slices and triggered the formation of pits as revealed by a pitting assay. Gene expression for osterix (OSX) and IGF-2, genes associated with bone formation, was significantly greater in FGF2-treated OVX rats compared with EP4A-treated OVX rats. These findings at the molecular level are consistent with previous tissue-level histomorphometric findings, and at the doses tested, support the contention that FGF2 has a stronger bone anabolic effect than EP4A. The results of these in vivo and in vitro analyses clarify the effects of FGF2 and EP4A on bone formation and resorption, and provide insight into differences in the efficacy of two potential bone anabolic agents for restoration of lost bone mass in the osteopenic, estrogen-deplete skeleton.
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Affiliation(s)
- M E Downey
- Department of Physiological Sciences, University of Florida, PO Box 100144, JHMHC, Gainesville, FL 32610-0144, USA.
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Abstract
The cellular and molecular events responsible for reduced fracture healing with aging are unknown. Cyclooxygenase 2 (COX-2), the inducible regulator of prostaglandin E(2) (PGE(2)) synthesis, is critical for normal bone repair. A femoral fracture repair model was used in mice at either 7-9 or 52-56 wk of age, and healing was evaluated by imaging, histology, and gene expression studies. Aging was associated with a decreased rate of chondrogenesis, decreased bone formation, reduced callus vascularization, delayed remodeling, and altered expression of genes involved in repair and remodeling. COX-2 expression in young mice peaked at 5 days, coinciding with the transition of mesenchymal progenitors to cartilage and the onset of expression of early cartilage markers. In situ hybridization and immunohistochemistry showed that COX-2 is expressed primarily in early cartilage precursors that co-express col-2. COX-2 expression was reduced by 75% and 65% in fractures from aged mice compared with young mice on days 5 and 7, respectively. Local administration of an EP4 agonist to the fracture repair site in aged mice enhanced the rate of chondrogenesis and bone formation to levels observed in young mice, suggesting that the expression of COX-2 during the early inflammatory phase of repair regulates critical subsequent events including chondrogenesis, bone formation, and remodeling. The findings suggest that COX-2/EP4 agonists may compensate for deficient molecular signals that result in the reduced fracture healing associated with aging.
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Highly conserved surface proteins of oral spirochetes as adhesins and potent inducers of proinflammatory and osteoclastogenic factors. Infect Immun 2008; 76:2428-38. [PMID: 18390996 DOI: 10.1128/iai.01128-07] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Oral spirochetes include enormously heterogeneous Treponema species, and some have been implicated in the etiology of periodontitis. In this study, we characterized highly conserved surface proteins in four representative oral spirochetes (Treponema denticola, T. lecithinolyticum, T. maltophilum, and T. socranskii subsp. socranskii) that are homologs of T. pallidum Tp92, with opsonophagocytic potential and protective capacity against syphilis. Tp92 homologs of oral spirochetes had predicted signal peptides (20 to 31 amino acids) and molecular masses of 88 to 92 kDa for mature proteins. They showed amino acid sequence identities of 37.9 to 49.3% and similarities of 54.5 to 66.9% to Tp92. The sequence identities and similarities of Tp92 homologs of oral treponemes to one another were 41.6 to 71.6% and 59.9 to 85.6%, respectively. The tp92 gene homologs were successfully expressed in Escherichia coli, and the recombinant proteins were capable of binding to KB cells, an epithelial cell line, and inhibited the binding of the whole bacteria to the cells. Antiserum (the immunoglobulin G fraction) raised against a recombinant form of the T. denticola Tp92 homolog cross-reacted with homologs from three other species of treponemes. The Tp92 homologs stimulated various factors involved in inflammation and osteoclastogenesis, like interleukin-1beta (IL-1beta), tumor necrosis factor alpha, IL-6, prostaglandin E(2), and matrix metalloproteinase 9, in host cells like monocytes and fibroblasts. Our results demonstrate that Tp92 homologs of oral spirochetes are highly conserved and may play an important role in cell attachment, inflammation, and tissue destruction. The coexistence of various Treponema species in a single periodontal pocket and, therefore, the accumulation of multiple Tp92 homologs may amplify the pathological effect in periodontitis.
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Noguchi M, Kimoto A, Sasamata M, Miyata K. Micro-CT imaging analysis for the effect of celecoxib, a cyclooxygenase-2 inhibitor, on inflammatory bone destruction in adjuvant arthritis rats. J Bone Miner Metab 2008; 26:461-8. [PMID: 18758904 DOI: 10.1007/s00774-008-0855-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2007] [Accepted: 01/17/2008] [Indexed: 10/14/2022]
Abstract
Cyclooxygenase (COX)-2 is known to play an important role in the differentiation and maturation of osteoclasts. However, the role of COX-1 in bone metabolism has not been well explored. In this study, the bone-conserving effects of COX-2-specific (celecoxib), COX-nonselective (loxoprofen), and COX-1-specific agents (SC-58560) were compared using an adjuvant-induced arthritis (AIA) rat model. Arthritis was induced by injecting 50 microl liquid paraffin containing 1 mg Mycobacterium butyricum into the left footpad of Lewis rats. Drugs were given orally twice daily for 10 days beginning 15 days after adjuvant injection. Celecoxib was administered at the rate of 3 mg/kg per day, loxoprofen at 3 mg/kg per day, and SC-58560 at 10 mg/kg per day. The therapeutic effects on 3-D architectural bone changes in the arthritic condition, e.g., the bone volume/total tissue volume ratio and the amount of trabecular bone pattern factor, were determined by analyzing the hindpaw calcaneus of AIA rats using microcomputed tomography (micro-CT). In addition, dual-energy X-ray absorptiometry 2-D bone analysis was performed to compare with micro-CT analysis. AIA rats are prone to substantial bone erosion, which allows for significant changes in the 3-D architectural index. This inflammatory bone destruction was suppressed potently by celecoxib, only moderately by loxoprofen, and not at all by SC-58560. These data suggest that COX-2 plays an important role in the inflammatory bone destruction that occurs with rheumatoid arthritis. The results also suggest that COX-2 is more effective than COX-1 at suppressing the destruction of bone associated with arthritis.
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Affiliation(s)
- Masahiro Noguchi
- Pharmacology Research Laboratories, Drug Discovery Research, Astellas Pharma Inc., 21 Miyukigaoka, Tsukuba, Ibaraki, Japan.
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Poulsen RC, Wolber FM, Moughan PJ, Kruger MC. Long chain polyunsaturated fatty acids alter membrane-bound RANK-L expression and osteoprotegerin secretion by MC3T3-E1 osteoblast-like cells. Prostaglandins Other Lipid Mediat 2007; 85:42-8. [PMID: 18077200 DOI: 10.1016/j.prostaglandins.2007.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Revised: 06/26/2007] [Accepted: 10/25/2007] [Indexed: 12/11/2022]
Abstract
Inflammation triggers an increase in osteoclast (bone resorbing cell) number and activity. Osteoclastogenesis is largely controlled by a triad of proteins consisting of a receptor (RANK), a ligand (RANK-L) and a decoy receptor (osteoprotegerin, OPG). Whilst RANK is expressed by osteoclasts, RANK-L and OPG are expressed by osteoblasts. The long chain polyunsaturated fatty acid (LCPUFA) arachidonic acid (AA, 20:4n-6) and its metabolite prostaglandin E2 (PGE2), are pro-inflammatory and PGE2 is a potent stimulator of RANKL expression. Various LCPUFAs such as eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3) and gamma-linolenic acid (GLA, 18:3n-6) have anti-inflammatory activity. We aimed to determine if AA itself can stimulate RANKL expression and whether EPA, DHA and GLA inhibit RANKL expression in osteoblasts. MC3T3-E1/4 osteoblast-like cells were cultured under standard conditions with each of the LCPUFAs (5microg/ml) for 48h. Membrane-bound RANKL expression was measured by flow cytometry and OPG secretion measured by ELISA. In a second experiment, RANKL expression in MC3T3-E1/4 cells was stimulated by PGE2 treatment and the effect of EPA, DHA and GLA on membrane-bound RANKL expression and OPG secretion determined. The percentage of RANKL-positive cells was higher (p<0.05) than controls following treatment with AA or GLA but not after co-treatment with the cyclooxygenase inhibitor, indomethacin. DHA and EPA had no effect on membrane-bound RANKL expression under standard cell culture conditions. Secretion of OPG was lower (p<0.05) in AA-treated cells but not significantly different from controls in GLA, EPA or DHA treated cells. Treatment with prostaglandin E2 (PGE2) resulted in an increase (p<0.05) in the percentage of RANK-L positive cells and a decrease (p<0.05) in mean OPG secretion. The percentage of RANKL positive cells was significantly lower following co-treatment with PGE2 and either DHA or EPA compared to treatment with PGE2 alone. Mean OPG secretion remained lower than controls in cells treated with PGE2 regardless of co-treatment with EPA or DHA. Results from this study suggest COX products of GLA and AA induce membrane-bound RANKL expression in MC3T3-E1/4 cells. EPA and DHA have no effect on membrane-bound RANKL expression in cells cultured under standard conditions however both EPA and DHA inhibit the PGE2-induced increase in RANKL expression in MC3T3-E1/4 cells.
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Affiliation(s)
- Raewyn C Poulsen
- Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand.
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70
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Namazi H. Practice Pearl: A Novel use of Botulinum toxin for Unicameral Bone Cyst Ablation. Ann Surg Oncol 2007; 15:657-8. [DOI: 10.1245/s10434-007-9644-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2007] [Accepted: 09/11/2007] [Indexed: 11/18/2022]
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71
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Abstract
In order to accommodate individual load, the skeletal system is in a continual state of change. Bone metabolism guarantees optimal bone structure. The osteoblasts are responsible for the synthesis and the osteoclasts for resorption of the bone. A finely adjusted interplay between molecular mechanisms leads, via cytokines, hormones and growth factors, to an homeostasis in bone metabolism. Disturbances of this process lead via increased bone resorption to osteoporosis, and via increased synthesis to osteopetrosis. This contribution describes the known molecular mechanisms in this remodelling process.
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Affiliation(s)
- E Neumann
- Abteilung für Innere Medizin und Rheumatologie, Justus-Liebig-Universität, Giessen
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