致敏淋巴细胞对破骨细胞分化及骨吸收的影响

目的；研究致敏淋巴细胞对破骨细胞分化及骨吸收功能的影响。方法：从被骨水泥单体甲基丙烯酸甲酯（MMA）致敏的新西兰兔外周血中分离淋巴细胞并提取培养介质（LCM），分离培养兔颅骨成骨细胞和兔骨髓细胞，通过抗酒石酸酸性磷酸酶（TrACP)染色和骨磨片扫描电镜观察对破骨细胞进行鉴定。在成骨细胞与骨髓细胞的培养体系中，分别在无LCM，未经MMA刺激的LCM和经MMA刺激的LCM等3种情况下，进行成熟破骨细胞计数和TrACP活性检测。结果：骨髓细胞能够分化成破骨细胞并且能在骨磨片上形成骨吸收陷窝，致敏淋巴细胞培养介质能够明显促进破骨细胞数量的增加和TrACP的分泌，在加入MMA刺激后，这种作用更加显著。结论：致敏淋巴细胞能够促进骨髓破骨细胞的分化和骨吸收能力。     

鸡破骨细胞分离培养方法的建立

为了寻找一种获得大量、纯化、有活力的破骨细胞的方法，我们对已经建立的兔破骨细胞体外分离培养方法的基础上加以改进。利用冲洗的方法，从２８天的鸡的长骨中得到细胞团１破骨细胞后，又对鸡的长骨相继进行胶原酶和胰蛋白酶的消化，得到细胞团２和细胞团３破骨细胞。将这些分离的细胞与盖玻片或骨磨片共同培养，通过相差显微镜观察到：这些分离的多核巨细胞能够运动，并能在骨磨片上形成吸收陷窝。另外，这些细胞对酸性磷酸酶染色呈阳性反应，而酸性磷酸酶是鉴别破骨细胞的标志。表明此分离培养鸡破骨细胞的实验技术是成功的。通过此方法获得的鸡破骨细胞比用以往方法获得的兔破骨细胞量多，且活力强。本方法的建立，为进一步研究骨吸收机理奠定了基础。     

阿司匹林对大鼠破骨细胞分化成熟和骨吸收活性的影响

目的 研究不同浓度阿司匹林对体外培养大鼠破骨细胞(Osteoclast,OC)分化成熟及骨吸收活性的影响.方法 建立由核激活因子受体配体(receptor activator of NF-κB ligand,RANKL)和巨噬细胞集落刺激因子(Macrophage colony stimulating factor,M-CSF)共同作用的大鼠破骨细胞骨髓诱导体系,将雌激素(10-6 mmol/L)和不同浓度的阿司匹林(0.25 mmol/L、0.5 mmol/L、1.0 mmol/L、1.5 mmol/L)分别作用于破骨细胞.诱导培养后分别对破骨细胞进行抗酒石酸酸性磷酸酶(The tartrate-resistant acid phosphatase,TRAP)染色,观察细胞形态,并计数破骨样细胞数量;将各组破骨细胞接种于骨磨片上,建立破骨细胞-骨磨片活性分析模型,于不同时间点对骨磨片进行光镜和扫描电镜观察,分析计算骨吸收陷窝面积.结果 与正常对照组相比,雌激素组破骨细胞数量和骨吸收陷窝面积低于正常对照组,差异有统计学意义(P＜0.05);且随着阿司匹林浓度的增加,阿司匹林组TRAP阳性多核破骨细胞数量、骨吸收陷窝面积逐渐减少直至消失,差异有统计学意义(P＜0.05).与雌激素组相比,低浓度阿司匹林组(0.25mmol/L)没有明显差异;但中、高浓度阿司匹林实验组(0.5mmol/L、1.0mmol/L、1.5mmol/L)破骨细胞数量和骨吸收陷窝面积减少,差异有统计学意义(P＜0.05).结论 阿司匹林对破骨细胞的分化成熟及骨吸收功能有抑制作用,且呈剂量依赖性,从而具有抗骨质疏松的作用.     

β转化生长因子在骨改建中的作用

β转化生长因子(TGF-β)在骨改建中起突出的作用。TGF-β刺激基质蛋白合成,对与骨形成及骨吸收有关的细胞有作用。TGF-β在骨及以骨为条件的介质中很丰富。根据骨细胞表型及其分化的阶段,TGF-β可以有多种作用。根据成骨细胞的类型,TGF-β可以引起分化或增殖。TGF-β抑制破骨细胞前身的形成,抑制骨吸收,高浓度时还抑制分离破骨细胞。TGF-β在骨吸收及骨形成之间起偶合作用。     

骨免疫学研究进展

骨重塑主要通过成骨细胞和破骨细胞之间相互作用而进行,其中RANKL-RANK-OPG系统在骨吸收和骨形成的耦联中起着关键作用.巨噬细胞集落刺激因子与其受体结合对破骨细胞发展是必须的.近年发现,成骨细胞还可与破骨细胞直接通过ephrin-Eph途径双向促进骨形成.免疫细胞和骨细胞共同起源于骨髓,从起始、成熟到活化,存在着相互影响.免疫细胞和骨细胞间通过许多细胞因子及其受体相互作用,调节骨代谢平衡,存在共同的骨代谢转录因子和信号转导途径.脂肪因子作为骨骼、免疫、脂肪系统的共同交叉机制,通过影响免疫细胞、成骨细胞或破骨细胞,进一步影响骨重塑方向.越来越多研究证实,骨免疫参予许多骨科疾病的发生与发展,揭示免疫系统对骨代谢的重要调节作用,有助于有效地预防和治疗骨科相关疾病.     

骨水泥颗粒促进肿瘤坏死因子α诱导的破骨细胞形成及其骨吸收作用

目的:验证骨水泥颗粒对肿瘤坏死因子α(TNFα)诱导的破骨细胞形成及其生物学活性的影响。方法:体外培养外周血单核细胞,对照组加入TNFα和白细胞介素-1α(IL-1α)及巨噬细胞克隆集落刺激因子(M-CSF),实验组并分别加入含有或不含有硫酸钙的骨水泥(PMMA±BaSO4)颗粒。对培养终末细胞作组织化学染色检测破骨细胞标志物抗酒石酸酸性磷酸酶(TRAP)的表达,并以象牙磨片上虫蚀样骨吸收陷窝的形成为指标检测破骨细胞的生物学活性;并比较各实验组中TRAP阳性多核细胞(multinucleatedcells,MNCs)及虫蚀样骨吸收陷窝形成时间的早晚。结果:各组TRAP阳性MNCs的数量无明显差异;PMMA±BaSO4组象牙磨片上骨吸收陷窝的面积均较对照组大,差异具有显著性(P<0.01);并且PMMA±BaSO4组TRAP阳性的MNCs及虫蚀样骨吸收陷窝的形成均较对照组早。结论:PMMA±BaSO4颗粒能够促进TNFα诱导的破骨细胞分化提早发生并促进其骨吸收活性。     

体外破骨细胞分离培养方法的建立

本研究采用出生２４小时内的新生兔，从其四肢长骨中分离出破骨细胞，与盖玻片、骨磨片共同培养。相差显微镜观察到分离的多核细胞能够移动，并在骨片上形成吸收陷窝，扫描电镜观察到这些吸收陷窝内的胶原原纤维。另外，这些细胞用目前公认的鉴定破骨细胞的标志－酸性磷酸酶和降钙素染色，呈阳性反应。这些结果均表明：分离、培养破骨细胞的实验技术是成功的。     

辛伐他汀抑制甲状旁腺素相关肽诱导的破骨细胞生成和功能

目的:探讨辛伐他汀对骨髓来源的破骨细胞形成和功能的影响。方法:取Balb/C雄性小鼠双侧股骨和胫骨的骨髓,以不含血清的α-MEM培养液洗涤并收集骨髓细胞,再将细胞重新悬浮于含100 m l/L胎牛血清的α-MEM培养液中,细胞计数后,配成1.5×109/L的细胞悬液,同时加入甲状旁腺素相关肽(PTHrP)和不同剂量的辛伐他汀(10-7、10-6、10-5mol/L)于24孔培养板进行培养,并设阳性对照(只加PTHrP)和阴性对照(PTHrP和辛伐他汀都不加)组,每组均有1孔放置骨磨片1片,培养6 d后;去除上清,抗酒石酸(TRAP)染色检测培养板底部破骨细胞形成;骨磨片用甲苯胺蓝染色,电镜检测骨磨片的吸收陷窝。结果:小鼠骨髓细胞在PTHrP的诱导下获得大量的TRAP染色阳性的破骨细胞,骨磨片有吸收陷窝形成;用辛伐他汀(10-7、10-6mol/L)和PTHrP共同培养下TRAP染色阳性的破骨细胞形成数量均明显减少(P<0.01),辛伐他汀在10-5mol/L时则无TRAP染色阳性的破骨细胞形成;辛伐他汀在10-7mol/L时骨磨片有吸收陷窝的形成但少于阳性对照组(P<0.01),在10-6、10-5mol/L时骨磨片则无吸收陷窝的形成。结论:辛伐他汀对小鼠骨髓来源的破骨细胞的形成有着明显的抑制作用,并且呈剂量依赖关系。     

应用颅骨-破骨细胞联合培养体系研究先天性成骨不全破骨细胞骨吸收活性

目的 先天性成骨不全(OI)的主要临床表现为骨矿化过程不良,骨量丢失,骨骼畸形和骨折.但是其发病机理,尤其在其骨再建过程中成骨细胞(OB)及破骨细胞(OC)的功能改变尚不清楚.本实验以先天性成骨不全小鼠模型,oim/oim为基础,应用破骨细胞-颅骨联合培养体系研究OB和OC两种细胞在骨再建过程中的功能改变和相互作用.方法 本实验采用小鼠颅骨(CAL)组织培养模型.本模型采用颅骨组织培养,利用颅骨中成骨细胞可以从颅骨片游离出到培养皿及颅骨表面,从而支持培养皿及颅骨表面前体破骨细胞分化成为成熟破骨细胞,并吸收颅骨产生吸收陷窝.本实验中,共2组颅骨-破骨细胞联合培养体系:(1) 对照组(WT)颅骨与对照破骨细胞(WTCAL-WTOC);(2) OI颅骨与OI破骨细胞(OICAL-OIOC).联合培养颅骨及骨髓组织14日后,以TRAP免疫组化染色方法识别破骨细胞,ALP免疫组化染色方法识别成骨细胞,计算OC/OB.破骨细胞骨吸收活性以颅骨表面骨吸收陷窝占颅骨表面百分比并除以培养系统中的破骨细胞数表达.结果 第14日,OICAL-OIOC组的破骨细胞数低于WTCAL-WTOC组(92.50+23.18/mm2 对比 379.00+ 136.53/mm2,P<0.01); OICAL-OIOC组的OC/OB明显低于WTCAL-WTOC组(0.68+0.57对比1.65+0.67,P<0.01);OICAL-OIOC组OI破骨细胞的吸收能力高于WTCAL-WTOC组(27.76+22.81对比7.32+5.09,P<0.001).结论 oim/oim小鼠破骨细胞-颅骨培养体系中破骨细胞的数目明显减少,成骨细胞支持破骨细胞分化能力减低;但其破骨细胞骨吸收活性明显增强,以代偿成骨细胞功能,维持骨再建过程中成骨过程及骨吸收过程的平衡.     

小鼠成骨细胞和破骨细胞共培养模型的建立

目的 建立小鼠成骨细胞和破骨细胞共培养模型,为探讨成骨细胞和破骨细胞之间的相互调控作用奠定基础.方法 利用24 h内新生小鼠颅骨和4～8周龄成年小鼠四肢长骨分别分离、培养成骨细胞和破骨细胞,采用间接接触的培养模式将接种了骨髓单核细胞的玻片或骨片置入提前24 h接种了成骨细胞的培养皿中进行共培养.共培养一定时间后进行破骨细胞抗酒石酸酸性磷酸酶(tartrate-resistant acid phosphatase,TRAP)染色鉴定和骨吸收功能检测,并进一步采用RT-PCR对破骨细胞标志酶基因基质金属蛋白酶.9(MMP-9)、TRAP 和组织蛋白酶K (Cathepsin K ) 的表达进行检测.结果 共培养5天后可见TRAP( )多核细胞形成,13天TRAP( )多核细胞数目达到高峰;骨吸收陷窝在共培养7天后开始出现,随着培养时间的延长,陷窝面积呈增加趋势;破骨细胞标志基因TRAP 在共培养3天时开始表达,而MMP-9和 Cathepsin K则在共培养5天后表达.结论 共培养体系中成骨细胞对破骨细胞调控作用显著,诱导的破骨细胞具有噬骨能力,该共培养模型可用于成骨细胞和破骨细胞之间的相互调控作用研究.     

Titanium particles stimulate bone resorption by inducing differentiation of murine osteoclasts

BACKGROUND: Loosening of orthopaedic implants is mediated by cytokines that elicit bone resorption and are produced in response to phagocytosis of implant-derived wear particles. This accelerated bone resorption could be due to increased osteoclastic activity, survival, or differentiation. Although a number of in vitro studies have shown that wear particles increase osteoclastic activity, the increase was less than twofold in all cases. The objective of the current study was to test the hypothesis that wear particles stimulate bone resorption by inducing osteoclast differentiation. METHODS: Conditioned media were prepared from murine marrow cells or human peripheral blood monocytes incubated in the presence or absence of titanium particles. The effects of conditioned media on osteoclast differentiation were examined with use of a recently developed assay in which osteoclast precursors are co-cultured with mesenchymal support cells. RESULTS: The present study showed that titanium particles induced both murine marrow cells and human peripheral blood monocytes to produce factors that stimulated osteoclast differentiation. The mean increase in osteoclast differentiation was 29.3+/-9.4-fold. The stimulation of osteoclast differentiation led to a parallel increase in bone resorption. The amount of stimulation was regulated in a dose-dependent manner by the concentration of both titanium particles and conditioned media. The stimulation of osteoclast differentiation required interactions between the cells and the particles themselves and, therefore, was not due to metal ions, soluble contaminants released from the particles, or submicrometer particles. In contrast, conditioned media from control cells incubated in the absence of titanium particles had no detectable effect on any of the examined parameters. CONCLUSIONS: The present study showed that titanium particles stimulate in vitro bone resorption primarily by inducing osteoclast differentiation. In contrast, the titanium particles had only small effects on osteoclast activity or survival.     

A novel synthetic triazolotriazepine derivative JTT-606 inhibits bone resorption by down-regulation of action and production of bone resorptive factors.

In the search for a new class of bone-sparing agents, we have conducted random screening of the domestic chemical library using 45Ca release assay from prelabeled cultured neonatal mouse calvariae and identified a novel synthetic triazolotriazepine JTT-606 as a candidate for a potent inhibitor of bone resorption. JTT-606 inhibited 45Ca release dose dependently not only in the control calvarial culture but also in the stimulated cultures by interleukin-1alpha (IL-1alpha), fibroblast growth factor 2 (FGF-2), and parathyroid hormone (PTH). JTT-606 also inhibited both basal and stimulated osteoclast-like (OCL) cell formation in the coculture of mouse osteoblastic cells and bone marrow cells dose dependently, indicating its inhibitory effect on osteoclast differentiation. Ex vivo OCL cell formation by cultured bone marrow cells collected from ovariectomized (OVX) mice also was decreased dose dependently by in vivo application of JTT-606 to a level similar to that from sham-operated mice. Furthermore, JTT-606 inhibited resorbed pit formation by isolated mature osteoclasts as well as by unfractionated bone cells derived from rabbit long bones in the control and FGF-2-stimulated cultures dose dependently, indicating both the direct and the indirect actions of JTT-606 on mature osteoclast function. In addition, JTT-606 reduced production of IL-1alpha, tumor necrosis factor alpha (TNF-alpha), IL-6, and granulocyte-macrophage colony-stimulating factor (GM-CSF) in the human peripheral blood mononuclear cell culture. In vivo analyses of mature OVX rats revealed that the application of JTT-606 for 12 weeks increased the BMD of the lumbar spine and decreased the levels of serum osteocalcin and urine deoxypyridinoline to levels similar to those of 17beta-estradiol-treated OVX rats. We propose that JTT-606 may inhibit both osteoclast differentiation and function by down-regulating both the action and the production of bone resorptive factors. It is speculated that JTT-606 could be a potent agent for the treatment of osteopenic disorders with elevated osteoclastic bone resorption.     

A differentiation-inducing factor produced by the osteoblastic cell line MC3T3-E1 stimulates bone resorption by promoting osteoclast formation

We have reported that the differentiation-inducing factor (DIF) is present in conditioned medium of mouse osteoblast-like cell (MC3T3-E1) cultures. In the present study, the DIF from conditioned medium of MC3T3-E1 cells was partially purified and its biologic activity was examined. The DIF was purified by monitoring the induction of phagocytic activity of mouse myeloblastic leukemia cells (M1). The DIF induced differentiation of not only M1 cells but also mouse myelomonocytic cells (WEHI-3). Furthermore, the DIF increased the in vitro bone-resorbing activity and the osteoclast number in mouse calvaria. The increases were inhibited by the addition of either salmon calcitonin or indomethacin. When mouse bone marrow cells were cultured with the DIF for 8 days, formation of osteoclast-like multinucleated cells was stimulated dose dependently. The DIF from MC3T3-E1 cells appeared to be different from interleukin-1 (IL-1), tumor necrosis factor (TNF), and transforming growth factor beta (TGF-beta). These results suggest that the DIF partially purified from osteoblast-like cell cultures stimulates osteoclastic bone resorption by promoting differentiation and fusion of osteoclast progenitors to form multinucleated osteoclasts.     

Identification of biphenylcarboxylic acid derivatives as a novel class of bone resorption inhibitors.

A novel class of biphenylcarboxylic acid derivatives are described that inhibit osteoclastic bone resorption in vitro by promoting osteoclast apoptosis and that prevent ovariectomy-induced bone loss in vivo. The compounds act by a novel mechanism that seems to be distinct from existing antiresorptive drugs. INTRODUCTION: Many common bone diseases such as osteoporosis, Paget's disease, and cancer-associated bone disease are characterized by excessive bone loss caused by increased osteoclastic activity. Successful treatment of these diseases is based on osteoclast inhibition. The osteoclast inhibitory drugs that are currently available fall into relatively few mechanistic classes, indicating the need to identify novel antiresorptives. Here we describe a series of biphenylcarboxylic acid derivatives that have potent inhibitory effects on osteoclastic bone resorption in vitro and on ovariectomy-induced bone loss in vivo. MATERIALS AND METHODS: Compounds were tested for inhibitory effects on bone resorption in vitro using mouse osteoblast-bone marrow co-cultures, isolated rabbit osteoclasts, and mouse osteoclasts generated from bone marrow. Some experiments were also performed on human osteoclasts generated from peripheral blood mononuclear cells. We also investigated the effects of specific compounds on ovariectomy-induced bone loss in vivo in mice. RESULTS: One of the most potent compounds identified was the butanediol ester of biphenyl carboxylic acid (ABD056), which inhibited osteoclast formation in mouse osteoblast-bone marrow co-cultures by 50% (IC50) at a concentration of 26 microM and in macrophage-colony stimulating factor (M-CSF)- and RANKL-stimulated mouse bone marrow cultures with an IC50 of 8 microM. Mechanistic studies showed that ABD056 caused osteoclast apoptosis and inhibited TNFalpha-induced NF-kappaB activation. No inhibitory effects on osteoblast growth or differentiation were observed at concentrations of up to 100 microM. When administered to mice at doses of 5 and 10 mg/kg/day, ABD056 prevented ovariectomy-induced bone loss. CONCLUSIONS: Butanediol biphenylcarboxylic acid derivatives represent a new class of antiresorptive drug that might be of therapeutic value in the prevention and treatment of diseases characterized by osteoclast activation such as osteoporosis, cancer-associated bone disease, and Paget's disease of bone.     

Direct stimulation of osteoclastic bone resorption by bone morphogenetic protein (BMP)-2 and expression of BMP receptors in mature osteoclasts

Bone morphogenetic proteins (BMPs) play an important role in various kinds of pattern formation and organogenesis during vertebrate development. In the skeleton, BMPs induce the differentiation of cells of chondrocytic and osteoblastic cell lineage and enhance their function. However, the action of BMPs on osteoclastic bone resorption, a process essential for pathophysiological bone development and regeneration, is still controversial. In this study, we examine the direct effect of BMPs on osteoclastic bone-resorbing activity in a culture of highly purified rabbit mature osteoclasts. BMP-2 caused a dose- and time-dependent increase in bone resorption pits excavated by the isolated osteoclasts. BMP-4 also stimulated osteoclastic bone resorption. The increase in osteoclastic bone resorption induced by BMP-2 was abolished by the simultaneous addition of follistatin, a BMP/activin binding protein that negates their biological activity. Just as it increased bone resorption, BMP-2 also elevated the messenger RNA expressions of cathepsin K and carbonic anhydrase II, which are key enzymes for the degradation of organic and inorganic bone matrices, respectively. Type IA and II BMP receptors (BMPRs), and their downstream signal transduction molecules, Smad1 and Smad5, were expressed in isolated osteoclasts as well as in osteoblastic cells, whereas type IB BMPR was undetectable. BMPs directly stimulate mature osteoclast function probably mediated by BMPR-IA and BMPR-II and their downstream molecules expressed in osteoclasts. The results presented here expand our understanding of the multifunctional roles of BMPs in bone development.     

Expression of mouse osteoclast K-Cl Co-transporter-1 and its role during bone resorption.

To assess the role of Cl- transport during osteoclastic bone resorption, we studied the expression and function of K+/Cl- co-transporters (KCCs). KCC1 and chloride channel-7 were found to be expressed in mouse osteoclasts. The KCC inhibitor, R(+)-butylindazone (DIOA), KCC1 antisense oligo-nucleotides, and siRNA suppressed osteoclastic pit formation. DIOA also decreased Cl- extrusion and reduced H+ extrusion activity. These results show that KCC1 provides a Cl- extrusion mechanism accompanying the H+ extrusion during bone resorption. INTRODUCTION: Mice with deficient chloride (Cl-) channels, ClC7, show severe osteopetrosis, resulting from impairment of Cl- extrusion during osteoclastic bone resorption. However, the expression and functional role of Cl- transporters other than ClC7 in mammalian osteoclasts is unknown. The aim of this study was to determine expression of K+/Cl- co-transporters (KCCs) and their functional role for bone resorption in mouse osteoclasts. MATERIALS AND METHODS: Mouse osteoclasts were derived from cultured bone marrow cells with macrophage-colony stimulating factor (M-CSF) and RANKL or from co-culture of bone marrow cells and primary osteoblasts. We examined the expression of Cl- transporters using RT-PCR, immunochemical, and Western blot methods. The effects of Cl- transport inhibitors on H+ and Cl- extrusion were assessed by measuring intracellular H+ ([H+]i) and Cl- ([Cl-]i). The effects of inhibitors, antisense oligo-nucleotides, and siRNA for Cl- transporters on bone resorption activities were evaluated using a pit formation assay. RESULTS AND CONCLUSIONS: Mouse osteoclasts express not only ClC7 but also K+/Cl- co-transporter mRNA. The existence of KCC1 in the cell membrane of mouse osteoclasts was confirmed by immunochemical staining and Western blot analysis. KCC inhibitors and Cl- channels blockers increased [Cl-]i and [H+]i in resorbing osteoclasts, suggesting that the suppression of Cl- extrusion through KCC and Cl- channels leads to reduced H+ extrusion activity. The combination of both inhibitors greatly suppressed these extrusion activities. KCC inhibitors and Cl- channel blockers also decreased osteoclastic bone resorption in our pit area essay. Furthermore, KCC1 antisense oligo-nucleotides and siRNA suppressed osteoclastic pit formation as well as treatment of ClC7 inhibitors. These results indicate that K+/Cl- co-transporter-1 expressed in mouse osteoclasts acts as a Cl- extruder and plays an important role for H+ extrusion during bone resorption.     

Effect of interleukin-17 on nitric oxide production and osteoclastic bone resorption: is there dependency on nuclear factor-kappaB and receptor activator of nuclear factor kappaB (RANK)/RANK ligand signaling?

Interleukin-17 (IL-17) is a proinflammatory cytokine produced exclusively by activated memory T cells and has recently been found to stimulate osteoclastic resorption. Like other proinflammatory cytokines, IL-17 may affect osteoclastic bone resorption indirectly via osteoblasts, possibly by mechanisms previously reported for chondrocytes that respond in very similarly to osteoblasts. As in chondrocytes, but only in combination with tumor necrosis factor-alpha (TNF-alpha), IL-17 induced nitric oxide (NO) production in osteoblastic cells and fetal mouse metatarsals by a nuclear factor-kappaB (NF-kappaB)-dependent mechanism. This effect was associated with elevated mRNA levels of the NF-kappaB isoforms RelA and p50. In fetal mouse metatarsals, IL-17 stimulated osteoclastic bone resorption only in combination with TNF-alpha. The pathway by which the cytokine combination exerts this effect was examined using inhibitors of NO synthesis and NF-kappaB activation. Although both inhibitors used abolished NO production, they did not prevent the stimulatory effect of the cytokine combination on osteoclastic resorption. In contrast, the inhibitors slightly increased osteoclastic resorption, suggesting a suppressive rather than stimulatory effect of NO on cytokine-induced bone resorption. In addition, we showed that IL-17 + TNF-alpha stimulated osteoclastic resorption independent of NF-kappaB signaling. To further examine the pathway by which osteoclastic resorption was stimulated, we used osteoprotegerin, a specific inhibitor of the receptor activator of NF-kappaB (RANK)/receptor activator of the NF-kappaB ligand (RANKL) pathway. Osteoprotegerin partially inhibited IL-17 + TNF-alpha-stimulated osteoclastic resorption only at the high concentration of 1000 ng/mL, whereas it completely blocked parathyroid hormone-related peptide-stimulated resorption at 300 ng/mL. In conclusion, IL-17 stimulated NO production by an NF-kappaB-dependent pathway in osteoblastic cells and fetal mouse metatarsals only in combination with TNF-alpha. Neither NO production nor NF-kappaB signaling, and only partly the RANK/RANKL pathway, were involved in the stimulatory effect of the cytokine combination on osteoblastic bone resorption in these long bones, suggesting the existence of other pathways by which osteoclastic resorption can be stimulated.     

Erythromycin inhibits wear debris-induced osteoclastogenesis by modulation of murine macrophage NF-kappaB activity.

Activation of nuclear factor kappa B (NF-kappaB) signaling in response to cell stimulation by wear debris may be critical in the pathogenesis of aseptic loosening. Erythromycin (EM), a macrolide antibiotic, has been shown to effectively suppress some types of inflammatory reactions. In this study, we examined the effect of EM on wear debris-induced osteoclastic bone resorption in vitro. EM inhibited Ca+ release from neonatal calvaria co-cultured with conditioned medium from mouse RAW264.7 macrophages activated by wear debris. Inhibition of Ca+ release was associated with a decreased number of tartrate-resistant acid phosphatase (TRAP)-positive cells in cultured bones. To investigate the mechanism whereby EM inhibits bone-resorption, RAW cells were incubated with wear debris in the presence EM. Real time RT-CR analysis revealed that EM (5 microg/ml) significantly inhibited mRNA expression of NF-kappaB, cathepsin K (CPK), IL-1beta and TNFalpha, but not RANK in RAW cells stimulated with wear debris. Furthermore, electrophoretic mobility-shift assay showed that EM (0.2 microg-5 microg/ml) could reduce DNA-binding activity of NF-kappaB in RAW cells stimulated with wear debris. The inhibition of inflammatory osteoclastogenesis by EM treatment was further confirmed by an osteoclast (OC) formation assay using primary cultures of mouse bone marrow progenitor cells stimulated with macrophage colony-stimulating factor and RANK ligand (RANKL). EM treatment (5 microg/ml) resulted in more than 70% reduction in multinucleated OC formation and 50% reduction of TRAP+ cells by bone marrow progenitor cells. Our findings support that EM suppresses wear debris-induced osteoclastic bone resorption by, at least, down-regulation of NF-kappaB signaling pathway. It appears that EM represents a potential therapeutic candidate for the treatment and prevention of aseptic loosening.     

辛伐他汀对PTHrP诱导的破骨细胞性骨吸收及小鼠颅盖骨代谢的影响

[目的]探讨辛伐他汀对体外甲状旁腺素相关肽（PTHrP）诱导小鼠的破骨细胞骨吸收功能的作用及其小鼠骨代谢的影响。[方法]采用PTHrP诱导小鼠骨髓细胞培养破骨细胞和小鼠颅盖骨培养体系，检测辛伐他汀作用8d后破骨细胞骨吸收陷窝和培养上清钙的变化；检测小鼠颅盖骨培养上清碱性磷酸酶和钙含量，组织学观察小鼠颅盖骨形态学变化。[结果]辛伐他汀体外可明显抑制PTHrP诱导小鼠的破骨细胞骨吸收陷窝的形成及培养上清钙的释放，辛伐他汀体外可增强小鼠颅盖骨培养上清碱性磷酸酶的活性，组织学观察到辛伐他汀使小鼠颅盖骨矿化增强。[结论]辛伐他汀体外不仅可促进小鼠颅盖骨的成骨活性，并且可明显抑制PTHrP诱导小鼠的破骨细胞骨吸收功能，对骨吸收性疾病有着重要的防治作用。