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。     

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.     

体外培养破骨细胞的功能观察

观察破骨细胞在离体状态下的骨吸收功能。新鲜牛皮质骨经锯式切片机横切成５０μｍ厚０．５×０．５ｃｍ大小骨片。参照已建立的破骨细胞分离培养方法，从新生Ｗｉｓｔａｒ大鼠四肢长骨分离破骨细胞，培养于２．５ｃｍ细胞培养皿内或上述骨片上，相差倒置显微镜或扫描电镜观察，可见培养的细胞具有典型破骨细胞的形态特点，接种子骨片上的破骨细胞分别培养１、３、５、７天，扫描电镜观察，可见破骨细胞能在骨片表面形成吸收陷窝，其形态多样，深浅不一，边界清晰，底面粗糙，而且随培养时间延长，陷窝扩大，数量增多。结论，破骨细胞在体外培养条件下具有良好的骨吸收功能，可进行药物干预的研究。     

阿仑膦酸钠抑制破骨细胞体外吸收的研究

本研究利用体外分离培养的兔破骨细胞,观察第三代双膦酸盐阿仑膦酸钠（ａｌｅｎｄｒｏｎａｔｅ）对骨吸收的抑制作用。将ａｌｅｎｄｒｏｎａｔｅ加入培养液中使其最终浓度为０Ｍ,１μＭ,１０μＭ,１００μＭ。同时观察两组用ａｌｅｎｄｒｏｎａｔｅ盐溶液１００μＭ,５０μＭ浸泡的骨片对破骨细胞吸收功能的影响。用倒置光相差显微镜在不同时间点观察计数骨吸收陷窝并拍照。结果随着培养液内ａｌｅｎｄｒｏｎａｔｅ浓度增高,骨吸收陷窝数减少,面积亦减少。而用ａｌｅｎｄｒｏｎａｔｅ浸泡过的骨片上未见骨吸收陷窝。说明ａｌｅｎｄｒｏｎａｔｅ具有抑制破骨细胞体外骨吸收的作用。     

淫羊藿抑制颌骨骨吸收的体外实验研究

从乳兔长骨分离出培养破骨细胞，并与人下颌骨骨磨片体外共同培养，分别加入不同浓度(0，0．15，1．5和15mg／ml)的淫羊藿注射液，倒置相差显微镜观察破骨细胞形成的骨吸收陷窝，并对陷窝数目和面积进行图像分析，探讨淫羊藿对破骨细胞性颌骨骨吸收的影响。结果显示，与对照组相比，淫羊藿3个实验组(0．15，1．5和15mg／ml)均能有效抑制破骨细胞在下颌骨片上形成的吸收陷窝的数量和面积，并且抑制作用呈剂量依赖性递增。     

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。     

氟对破骨细胞骨吸收陷窝的影响

目的 观察氟对大鼠破骨细胞(Osteoclast,OC)形成的骨吸收陷窝的影响。方法 通过机械分离新生大鼠乳鼠四肢长骨方法体外培养Oc,并于1 d后加入含不同浓度氟的培养基,观察氟对OC形成的骨吸收陷窝数量及面积的影响。结果 随染氟剂量的增加,骨吸收陷窝数及陷窝面积逐渐增加,各剂量组与对照组比差异均有显著性(P<0.05),其中尤以4.0mg/L染氟组最为明显(P<0.01)。结论 在一定的剂量范围内,随染氟剂量的增加,OC的骨吸收作用是增强的。     

依降钙素对破骨细胞的作用观察

目的 观察了国产降钙素-依降钙素对破骨细胞体外骨吸收功能的影响。并与进口降钙素-益钙宁的作用比较，方法 由10日龄幼兔四肢长骨机械分离破骨细胞于199培养液（含10%NCS 5?S），分别接种于象牙薄切片和培养板，置37℃，5%CO2培养箱中培养，细胞骨架观察采用荧光标记法（罗达明标记的鬼笔环肽），骨片吸收陷窝计数采用甲苯胺蓝染色法，益钙宁为阳性对照，等量培养液为阴性对照，结果 依降钙素组破骨细胞F-actin聚集，变短，骨片培养3d，吸收陷窝计数的结果显示，10^-10mol/L以上浓度依降钙素对破骨细胞吸收功能有明显抑制作用，并呈剂量相关性，10^-1mol/L时的抑制作用高达90%；依降钙素和益钙宁的抑制作用呈高度相关（r=0.99）。结论 依降钙素具有明显的抑制体外培养破骨细胞骨吸收活性的作用，与益钙宁的作用相仿。     

17β-雌二醇对体外培养破骨细胞凋亡及其骨吸收调节作用

目的 观察17β-雌二醇对体外培养破骨细胞凋亡率的影响及其与骨吸收功能的关系。方法 在培养液中加入17β-雌二醇，透射电镜（transmission electron microscopy，TEM）观察破骨细胞内超微结构的改变，流式细胞仪（flow cytometry，FCM）观察不同浓度的17β-雌二醇在不同时间段对破骨细胞凋亡率的影响，同时用扫描电镜（scanning electron microscopy，SEM）观察破骨细胞在骨片上形成骨吸收陷窝数目及面积的变化。结果 17β-雌二醇可增加破骨细胞的凋亡率，这种作用具有剂量、时间依赖效应，同时，破骨细胞在骨片上形成的骨吸收陷窝的数目和面积减少。结论 17β-雌二醇可促进破骨细胞凋亡，从而抑制破骨细胞的骨吸收功能。     

密骨胶囊含药血清对骨吸收陷窝面积和深度的影响

目的 :探讨密骨胶囊含药血清对破骨细胞骨吸收陷窝面积和深度的影响。方法 :自 1d龄SD大鼠四肢长骨分离破骨细胞 ,接种于象牙薄片底物上 ,设密骨胶囊组、西药倍美力组和生理盐水对照组 ,同等条件下制备含药血清和对照血清 ,以 30 %的浓度添加于培养体系中 ;第 7天终止培养 ,经甲苯胺蓝染色 ,每组随机拍摄照片各 6张 ,采用计算机图像分析系统测算陷窝与背景面积的比值 ,以及陷窝的平均光密度值。结果 :对照组、倍美力组和密骨胶囊组陷窝面积比值分别为 0 2 75± 0 0 6 2、0 0 96± 0 0 10和 0 0 6 5± 0 0 13,密骨胶囊和倍美力含药血清抑制陷窝面积增大的作用非常显著 (P <0 .0 1) ;对照组、倍美力组和密骨胶囊组陷窝平均光密度值分别为 1 6 4 3± 0 35 6、1 0 88± 0 4 4 9和 0 6 35± 0 345 ,密骨胶囊含药血清可明显抑制陷窝的加深 (P <0 .0 1) ,而倍美力含药血清的作用不明显 (P >0 .0 5 )。结论 :密骨胶囊含药血清能够明显抑制象牙薄片上骨吸收陷窝面积的增大和深度的加深 ,这可能是其提高骨质量的机制之一。     

Emodin Regulates Bone Remodeling by Inhibiting Osteoclastogenesis and Stimulating Osteoblast Formation

Bone remodeling, a physiological process in which new bone is formed by osteoblasts and the preexisting bone matrix is resorbed by osteoclasts, is vital for the maintenance of healthy bone tissue in adult humans. Imbalances in this process can cause various pathological conditions, including osteoporosis. Emodin, a naturally occurring anthraquinone derivative found in Asian herbal medicines, has numerous beneficial pharmacologic effects, including anticancer and antidiabetic activities. However, the effect of emodin on the regulation of osteoblast and osteoclast activity has not yet been investigated. We show here that emodin is a potential target for osteoporosis therapeutics, as treatment with this agent enhances osteoblast differentiation and bone growth and suppresses osteoclast differentiation and bone resorption. In this study, emodin suppressed receptor activator of nuclear factor‐κB (NF‐κB) ligand (RANKL)‐induced osteoclast differentiation of bone marrow macrophages (BMMs) and the bone‐resorbing activity of mature osteoclasts by inhibiting RANKL‐induced NF‐κB, c‐Fos, and NFATc1 expression. Emodin also increased ALP, Alizarin Red‐mineralization activity, and the expression of osteoblastogenic gene markers, such as Runx2, osteocalcin (OCN), and ALP in mouse calvarial primary osteoblasts, as well as activated the p38‐Runx2 pathway, which enhanced osteoblast differentiation. Moreover, mice treated with emodin showed marked attenuation of lipopolysaccharide (LPS)‐induced bone erosion and increased bone‐forming activity in a mouse calvarial bone formation model based on micro‐computed tomography and histologic analysis of femurs. Our findings reveal a novel function for emodin in bone remodeling, and highlight its potential for use as a therapeutic agent in the treatment of osteoporosis that promotes bone anabolic activity and inhibits osteoclast differentiation. © 2014 American Society for Bone and Mineral Research.     

Apoptotic Bodies Convey Activity Capable of Initiating Osteoclastogenesis and Localized Bone Destruction

Introduction: Osteocyte apoptosis co‐localizes with sites of osteoclastic bone resorption in vivo, but to date, no causal molecular or signaling link has been identified between these two processes. Materials and Methods: Osteocyte apoptotic bodies (OABs) derived from the MLO‐Y4 osteocyte‐like cell line and primary murine osteocytes and apoptotic bodies (ABs) derived from primary murine osteoblasts were introduced onto the right parietal bone of murine calvariae, and osteoclastic bone resorption was examined 5 days after treatment. In addition, the ability of primary murine and cell line–derived OABs to support osteoclastogenesis was examined in vitro in co‐culture with murine bone marrow hematopoietic progenitors in the absence of RANKL or macrophage‐colony stimulating factor. Results: For the first time, we show that OABs are capable of initiating de novo osteoclastic bone resorption on quiescent bone surfaces in vivo. Furthermore, the addition of OABs to mononuclear osteoclast precursors (OPs) in vitro resulted in the maintenance of OP cell numbers and an increase in the proportion and activity of TRACP⁺ cells. In contrast, application of ABs from osteoblasts showed no osteoclastogenic activity either in vivo or in vitro. The osteoclastogenic capacity of OABs was shown to be independent of the known osteoclastogenic factor RANKL but dependent on the induction of TNF‐α production by OP. Conclusions: These data point to a mechanism by which dying osteocytes might target bone destruction through the distribution of OAB‐associated signals and give further physiological meaning to the apoptotic process in bone.     

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.     

Suramin interacts with RANK and inhibits RANKL-induced osteoclast differentiation

Suramin is a naphthalene trisulfonic acid derivative that inhibits osteoclast differentiation and bone resorption in vitro and in vivo; however, the mechanisms underlying this activity have not been studied. Receptor activator of NF-kB (RANK) ligand (RANKL) is a key regulator of osteoclast differentiation and function and this study evaluated the ability of suramin, which has been shown to disrupt protein-protein interactions, to interfere with RANKL functional activity and binding to RANK. Suramin inhibited osteoclastic bone resorption in a calvarial model and inhibited osteoclast differentiation in RANKL-stimulated murine spleen cells and RAW264.7 cells. RANKL-induced second messenger signaling (AKT and p38 MAP Kinase phosphorylation) was completely blocked by 100 microM suramin. The ability of RANKL to bind to recombinant human RANK-Fc (rhRANK-Fc) was reduced 50% by suramin in an in vitro binding assay. Surface plasmon resonance technology and nuclear magnetic resonance (NMR) were used to evaluate the ability of suramin to bind to rhRANK-Fc. Suramin was found to selectively interact with immobilized rhRANK-Fc chimera in a concentration-dependent manner by Biacore 3000 analysis. Similar results were obtained using saturation transfer difference NMR spectroscopy to demonstrate that suramin binds to rhRANK-Fc, but not IgG1Fc or sRANKL. In summary, these findings demonstrate that suramin inhibits sRANKL-induced osteoclast differentiation and suggest that these effects are mediated by suramin binding to RANK and blocking the ability of sRANKL to induce second messenger signaling.     

The N-terminal fragment of osteocalcin is released during osteoclastic bone resorption in vitro

As a novel method for measuring bone resorption, an immunoassay system for human N-terminal osteocalcin (N-OC) was developed to determine if osteocalcin molecules are released from bone degraded by osteoclasts in vitro. The assay system employed a monoclonal antibody to the first 20 N-terminal residues of osteocalcin as the solid phase and polyclonal antibodies against these same residues as an enzyme conjugate. This assay system could detect the N-terminal portion of osteocalcin formed during the degradation of the human osteocalcin molecule by trypsin or cathepsin D. Osteoclasts were isolated from human alveolar bone and cultured on human bone slices; the osteocalcin content in the media from these cultures was measured by this N-OC assay method. The N-terminal fragment of osteocalcin was the major form of osteocalcin released during osteoclastic bone resorption along with small amounts of intact osteocalcin. Interleukin-1 (IL-1β) and interleukin-6 (IL-6), stimulators of osteoclastic bone resorption, increased the N-OC level by 1.5 fold compared with the level of N-OC in osteoclast cultures in the absence of stimulators. In contrast, treatment of the cultures with calcitonin or an inhibitor of cathepsin D (E-64), both of which inhibit osteoclastic bone resorption, decreased the amount of N-OC in the culture supernatants. These results suggest that the N-terminal fragment of osteocalcin is released during osteoclastic bone resorption and that its level may serve as an index of bone resorption in vitro. Received: June 2, 1997 / Accepted: Oct. 1, 1997     

Bisphosphonates suppress bone resorption by a direct effect on early osteoclast precursors without affecting the osteoclastogenic capacity of osteogenic cells: the role of protein geranylgeranylation in the action of nitrogen-containing bisphosphonates on osteoclast precursors.

Nitrogen-containing bisphosphonates (NBps) are taken up by osteoclasts and inhibit farnesyl pyrophosphate synthase, an enzyme of the mevalonate pathway. There is evidence, however, that cells other than mature osteoclasts, like osteoclast precursors and osteoblasts, are also involved in the action of Bps on bone resorption in vitro. To examine this issue further, we developed a new in vitro model, which allows the study of the effects of additives on early osteoclast precursors. In this model, osteogenic cells are essential for osteoclastogenesis. The model consists of 15-day-old fetal mouse metatarsals. At time of explantation, these bone rudiments do not yet contain a mineralized matrix or osteoclasts; only early osteoclast precursors are present in the perichondrium. During culture and after the addition of Nabeta-glycerolphosphate, the bones form a mineralized matrix that is consequently resorbed by osteoclasts that develop from their precursors. Short treatment of these explants with Bps, before the formation of a mineralized matrix, resulted in a subsequent dose-dependent inhibition of bone resorption. The relative potencies of eight Bps to suppress resorption were comparable with those observed after the addition of Bps after the formation of a mineralized matrix, the natural target of Bps. In addition, the effects of the NBp olpadronate, but not of clodronate, on osteoclastic resorption, could be partly reversed by geranylgeraniol. Results indicate that Bps can suppress osteoclastic resorption in vitro by a direct action on very early osteoclast precursors at the bone surface, and not by affecting the osteoclastogenic capacity of osteogenic cells. Moreover, the mechanism of action of the NBp olpadronate, but not clodronate, on early tartrate-resistant acid phosphatase-negative osteoclast precursors involves inhibition of protein geranylgeranylation, indicating a molecular mechanism similar to that established for mature osteoclasts.     

The pathogenesis of loosening of total hip arthroplasties. The production of factors by periprosthetic tissues that stimulate in vitro bone resorption

The production of factors capable of stimulating bone resorption in the newly formed periprosthetic capsule and in the bone-cement membrane obtained from patients reoperated due to aseptic loosening of cemented total hip prostheses was studied using organ culture techniques. Addition of culture media conditioned by membranes from six patients and bone-cement membranes from two patients to the mouse calvarial cultures resulted in a significantly increased release of calcium. The effect of capsule-conditioned media on calcium release was dose- and time-dependent and significantly reduced by the osteoclast inhibitor of calcitonin. Histologic analysis of bones at the end of the culture period showed that capsule-conditioned media enhanced the breakdown of mineralized bone and increased the number of osteoclasts. The observations showed that newly formed periprosthetic tissues from patients with loose total hip arthroplasties (THAs) can produce one or several factors that stimulate bone resorption in vitro by an osteoclast-mediated mechanism. Not only mechanical failure but also biologic reactions in the periprosthetic tissues eventually lead to osteoclast activation and may contribute to the loosening of THAs.     

Lipopolysaccharide-induced bone resorption is increased in TNF type 2 receptor-deficient mice in vivo

The release of tumor necrosis factor (TNF)-alpha from macrophages upon stimulation of lipopolysaccharide (LPS) is a major etiological factor of inflammatory bone disease and elicits the effects through TNF receptors type 1 and 2. Given the importance of TNF-alpha action on osteoclastic bone resorption, the role of TNF type 2 receptor (TNFR2) on bone resorption has not been elucidated well so far. The purpose of this study is to investigate the role of TNFR2 on LPS-induced inflammatory bone resorption in vivo. LPS at 10 mg/kg (Re 595) was injected subcutaneously on calvariae of wild-type (WT), TNF type 1 receptor (TNFR1)-deficient (KO), and TNFR2 KO mice, killed on day 5 after the LPS injection. The calvarial bone mineral density (BMD) was significantly decreased by LPS compared to the vehicle-injected control in WT mice, but not in TNFR1 KO mice. Interestingly, the decrease of calvarial BMD and the increase of the osteoclast number by LPS in TNFR2 KO mice seemed to be more than those in WT mice. Furthermore, the significant decrease by LPS on the BMD of tibiae, femurs, and lumber vertebrae were observed only in TNFR2 KO mice. Histomorphometric analysis of tibiae showed the significant increases of osteoclast number and surface in the LPS-injected TNFR2 KO mice, and the levels of urinary deoxypyridinoline reflected these increases of bone resorption parameters. The present data indicate that TNFR1 is critical for bone resorption at the site of LPS injection and that TNFR2 might have a protective role on the LPS-induced inflammatory bone resorption process.     

Smad4促进成骨分化的机制研究

目的 探讨Smad4基因促进成骨分化的作用机制。方法 采用条件性基因敲除技术Cre/loxp,制备骨细胞特异性敲除Smad4小鼠(Smad4otcko),小鼠胚胎骨骼透明染色分析胚胎期小鼠长骨生长状况;待小鼠成长至1月龄,X-ray检测突变小鼠与对照组小鼠的骨密度差异;静态骨组织形态学分析检测突变鼠及对照鼠的骨量变化、成骨细胞数量变化等差异;实时荧光定量PCR检测Smad4突变鼠股骨成骨细胞相关因子Runx2、ALP、OSX及OCN;破骨细胞TRAP染色分析Smad4突变鼠破骨细胞形态及数量变化;qPCR检测突变鼠股骨破骨吸收标志基因RANKL、OPG,并计算RANKL/OPG比率。结果 Smad4基因敲除小鼠在胚胎期未出现长骨生长异常。X线结果显示,1月龄时,与对照组小鼠相比,Smad4突变鼠的骨密度降低（P＜0.05）,静态骨组织形态学分析表明突变鼠松质骨减少,皮质骨变薄,骨小梁数量减少（P＜0.05）;Smad4突变鼠成骨细胞标志基因表达量显著降低,成骨细胞的数量明显减少（P＜0.05）;RANKL作为破骨吸收标志物表达上调、作为其拮抗剂的OPG表达量下调,RANKL/OPG比率增高（P＜0.05）。结论 Smad4基因通过促进成骨分化,降低破骨吸收从而来维持骨稳态。