Osteoclastogenesis inhibitory factor exhibits hypocalcemic effects in normal mice and in hypercalcemic nude mice carrying tumors associated with humoral hypercalcemia of malignancy

Osteoclastogenesis inhibitory factor (OCIF) is a novel secreted protein that inhibits osteoclastogenesis both in vitro and in vivo. In this study, we examined the effects of OCIF on serum calcium (Ca) concentrations in normal mice and in hypercalcemic nude mice carrying tumors associated with humoral hypercalcemia of malignancy. In normal mice, a single intraperitoneal injection of OCIF reduced serum Ca levels in a dose-dependent manner. Significant decrease in serum Ca (by 1.6 ± 0.3 mg/dL, n = 5) was observed 2 h after the injection of OCIF at 20 mg/kg and the hypocalcemic effect continued for up to 12 h. Serum phosphate (Pi) concentrations also decreased in response to OCIF. Urinary excretion of Ca, Pi, and creatinine did not change significantly after injection of OCIF or vehicle. In hypercalcemic, tumor-bearing nude mice, a single intraperitoneal injection of OCIF at 20 mg/kg resulted in a dramatic decrease in serum Ca (maximal decrease 2.8 ± 0.37 mg/dL, n = 11), which continued for up to 24 h. The results suggest that OCIF decreased serum Ca through its inhibitory effect on bone resorption. Furthermore, it is suggested that OCIF has therapeutic potential for the treatment of hypercalcemic conditions such as malignancy-associated hypercalcemia.     

交锁髓内钉与钢板内同定微创治疗胫腓骨多段骨折的病例对照研究

目的 :采用小鼠气囊模型评价柚皮苷对聚甲基丙烯酸甲酯(Polymethylmethacrylate,PMMA)诱发的破骨细胞性骨溶解的作用。方法:选取48只雌性8~10周龄Balb/c小鼠纳入研究,采用背部注入空气法在其中的32只小鼠中建立气囊模型,植入同种系小鼠颅骨(颅骨源自其余的16只小鼠)。实验共分为4组(150 mg/kg柚皮苷治疗组、30 mg/kg柚皮苷治疗组、PBS空白对照组、DMSO载体对照组),每组8只动物。对两个柚皮苷治疗组和DMSO载体对照组的小鼠使用PMMA颗粒刺激,每组8只相应浓度进行处理,颗粒刺激第7天收集囊膜和囊内植入骨进行抗酒石酸酸性磷酸酶(Tartrate resistant acid phosphatase,TRAP)染色、Ca2+释放以及改良Masson染色病理分析进行评价,观察柚皮苷的治疗作用。结果:与DMSO载体组相比,柚皮苷治疗组降低了TRAP阳性细胞浸润的数量,差异有统计学意义(P<0.01);其中150 mg/kg浓度优于30 mg/kg浓度(8.90±1.75 vs 15.23±1.86)。在气囊模型骨吸收冲洗液中,柚皮苷能降低钙的释放,特别是150 mg/kg浓度组更为明显(P<0.05)。改良的Masson染色显示柚皮苷可减少PMMA刺激所致的骨胶原的丢失,但150 mg/kg浓度组作用大于30 mg/kg浓度组。大体及病理切片显示两种浓度的柚皮苷显著降低PMMA刺激所致的炎性反应,表现为气囊厚度的减低和炎性细胞浸润数量的减少。结论 :柚皮苷抑制PMMA诱导的破骨细胞形成,有效缓解PMMA诱发的炎性反应以及随后发生的急性骨吸收。     

RANKL-independent modulation of osteoclastogenesis

Osteoclasts are functional cells required for bone resorption. They are derived from hematopoietic precursors and undergo a series of differentiation and fusion steps in response to various humoral factors. Depending on the importance in osteoclastogenesis, the pathways for the differentiation of hematopoietic precursors to mature osteoclasts can be divided into two categories: canonical and the non-canonical. Receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast formation is considered as an important canonical pathway. Non-canonical pathways of osteoclastogenesis mainly involve several humoral factors that can substitute for RANKL to induce osteoclast formation. Among these factors, tumor necrosis factor (TNF)-α, interleukin (IL)-1, “homologous to lymphotoxins, exhibiting inducible expression, and competing with herpes simplex virus glycoprotein D for herpesvirus entry mediator, a receptor expressed by T lymphocytes” (LIGHT), a proliferation-inducing ligand (APRIL), and B cell-activating factor (BAFF) belong to the TNF superfamily. Other RANKL substitutes are primarily cytokines and growth factors including transforming growth factor β (TGFβ), IL-6, IL-11, nerve growth factor (NGF), insulin-like growth factor (IGF)-I, and IGF-II. In this review, we summarize the involvement of these factors in inducing osteoclastogenesis in vitro. Although these factors weakly induce osteoclast formation, they may play a major role in pathological bone resorption.     

芒柄花素抑制RANKL诱导破骨细胞分化的实验研究

目的:建立RANKL诱导的破骨细胞体外研究模型,阐述活血化瘀中药鸡血藤有效组分芒柄花素(formononetin,FO)调控小鼠骨髓单核-巨噬细胞(BMMs)向破骨细胞分化和功能的影响,探讨其抑制破骨细胞分化的分子机制。方法:取20只4~6周龄清洁级C57/BL6小鼠,雌雄各10只,体重(20±2)g,无菌条件下分离出股骨和胫骨内BMMs,用α-MEM培养基进行体外培养和增殖。BMMs在加入M-CSF和不同浓度的芒柄花素(5~50?滋M)分别培养4 d后进行细胞增殖与毒性的CCK8检测。将生长状态良好的BMMs依次加入M-CSF和RANKL诱导破骨细胞分化,对照组无特殊处理,DMSO对照组加入DMSO溶剂,各观察组分别加入不同浓度芒柄花素(1~20?滋M),分别进行培养6 d后进行抗酒石酸酸性磷酸酶(TRAP)染色,对破骨细胞的进行计数和统计分析。分别在破骨细胞培养的1、2 d收取总蛋白和磷酸化蛋白,Western blot检测破骨细胞分化中关键转录因子NFATc1和c-Fos的表达以及磷酸化蛋白ERK表达;在培养的4 d提取RNA,Real-Time PCR检测破骨细胞相关基因CTSK、TRAP、MMP9和Car2的活性。结果:CCK8检测结果提示芒柄花素能够剂量依赖性地抑制BMMs的活性,在≤20?滋M的安全浓度范围内对BMMs细胞生长无明显毒性效应(P=0.278>0.05)。TRAP染色结果发现芒柄花素在(1~20?滋M)浓度范围内能够剂量依赖性的抑制破骨细胞的生成,尤其是10?滋M能够显著抑制破骨细胞的生成(P=0.000<0.05)。Western blot检测表明芒柄花素(10?滋M)能显著抑制破骨细胞分化关键蛋白NFATc1和c-Fos的表达,而对磷酸化蛋白ERK的表达未见明显的作用。在破骨细胞功能上,Real-Time PCR检测芒柄花素(10?滋M)能著抑制破骨细胞功能相关基因CTSK(P=0.000<0.05)、TRAP(P=0.000<0.05)、MMP9(P=0.000<0.05)和Car2(P=0.000<0.05)的表达。结论:鸡血藤有效组分芒柄花素能够抑制原代骨髓单核-巨噬细胞向破骨细胞增殖和分化,并下调破骨细胞骨吸收功能相关蛋白和基因的表达,可能是其防治股骨头坏死中骨破坏及塌陷的机制之一。     

SC-514, a selective inhibitor of IKKβ attenuates RANKL-induced osteoclastogenesis and NF-κB activation

The RANKL-induced NF-κB signaling pathway is essential for osteoclastogenesis. This study aims to identify specific inhibitors targeting NF-κB signaling pathway, which might serve as useful small molecule inhibitors for the treatment and alleviation of osteoclast-mediated bone lytic diseases. By screening for compounds that selectively inhibit RANKL-induced NF-κB activation in RAW264.7 cells as monitored by luciferase reporter gene assay, we identified SC-514, a specific inhibitor of IKKβ, as a candidate compound targeting osteoclastogenesis. SC-514 dose-dependently inhibits RANKL-induced osteoclastogenesis with an IC50 of <5 μM. At high concentrations, SC-514 (≥12.5 μM) induced apoptosis and caspase 3 activation in RAW264.7 cells. Moreover, SC-514 specifically suppressed NF-κB activity owing to delayed RANKL-induced degradation of IκBα and inhibition of p65 nuclear translocation. Taken together, our results indicate that SC-514 impairs RANKL-induced osteoclastogenesis and NF-κB activation. Thus, targeting IKKβ by SC-514 presents as a potential treatment for osteoclast-related disorders such as osteoporosis and cancer-induced bone loss.     

颅骨锁骨发育不全患者牙囊细胞的体外生物学特征

目的：在成功分离培养正常同龄人牙囊细胞（dental follicle cells,DFCs）与颅骨锁骨发育不全（cleidocranial dysplasia, CCD）患者牙囊细胞（DFCs-CCD）的基础上,研究其一般体外生物学特征,包括增殖、克隆、成骨及破骨能力。方法：采用 BrdU细胞增殖实验与倍增法研究两种来源 DFCs 增殖能力;用结晶紫染液染色培养12 d 的两种 DFCs,分析其克隆形成能力;并用成骨诱导液诱导两种 DFCs 成骨,用 Western blot 和茜素红染色法分析成骨能力,用实时定量 PCR 方法研究其破骨基因表达差异。结果：DFCs-CCD 的 BrdU 阳性率高于 DFCs,同时 DFCs 的群体倍增时间为（1．834±0．093）d,而 DFCs-CCD 的则为（1．394±0．028）d,差异具有统计学意义（P ＜0．05）;DFCs-CCD 的克隆集落多于 DFCs,但 Runt 相关转录因子2（Runt-related transcrip-tion factor 2,Runx2）、成骨细胞特异性转录因子 Osterix、骨钙素（osteocalcin,Ocn）等成骨相关蛋白表达水平低,而其茜素红染色所示钙化结节同样较少;同时,DFCs-CCD 高表达核因子-κB 受体活化因子（receptor activator for nuclear factor-κB,RANK）和骨保护素（osteoprotegerin,OPG）等破骨相关基因（P ＜0．05）,而核因子-κB 受体活化因子配体（receptor activator for nuclear factor-κB ligand,RANKL）水平无统计学差异（P ＞0．05）。结论：相比 DFCs,DFCs-CCD 具有更强的增殖、克隆能力和更弱的成骨能力,而破骨基因表达紊乱。     

Pressure-Loaded MSCs During Early Osteodifferentiation Promote Osteoclastogenesis by Increase of RANKL/OPG Ratio

Mechanical stress plays an important role in bone remodeling. However, it is still unclear whether mechanical stress regulates osteoclastogenesis mediated by mesenchymal stem cells (MSCs) during initial osteodifferentiation. We investigated the effects of static and dynamic pressures on osteoclast-inducing potential of MSCs during early osteodifferentiation. The osteoclastogenesis was examined using TRAP staining. The mRNA levels of receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) genes were analyzed using real-time RT-PCR. It was shown that MSCs exposed to either pressure during initial osteodifferentiation promoted osteoclastogenesis with the up-regulation of RANKL/OPG ratio. MSCs displayed diverse responses to pressures at different points of initial osteodifferentiation. The RANKL/OPG ratio was significantly increased after osteoinduction in the primary MSCs without pressures exposure, which contradicted the previous report. These results suggest novel mechanisms of the initial biological responses of bone remodeling upon mechanical stimuli.     

Inhibitory effects of erythromycin on wear debris-induced VEGF/Flt-1 gene production and osteolysis

Objectives  A highly vascularized and inflammatory periprosthetic tissue augments the progress of aseptic loosening, a major clinical problem after total joint replacement. The purpose of this study is to investigate the effect of erythromycin (EM) on ultra high molecular weight polyethylene (UHMWPE) particle-induced VEGF/VEGF receptor 1 (Flt-1) gene production and inflammatory osteolysis in a mouse model. Methods  UHMWPE particles were introduced into established air pouches on BALB/c mice, followed by implantation of calvaria bone from syngeneic littermates. EM treatment started 2 weeks after bone implantation (5 mg/kg day, i.p. injection). Mice without drug treatment as well as mice injected with saline alone were included. Pouch tissues were harvested 2 weeks after bone implantation. Expression of VEGF, Flt-1, RANKL, IL-1, TNF and CD68 was measured by immunostain and RT-PCR, and implanted bone resorption was analyzed by micro-CT (μCT). Results  Exposure to UHMWPE induced pouch tissue inflammation, increase of VEGF/Flt-1 proteins, and increased bone resorption. EM treatment significantly improved UHMWPE particle-induced tissue inflammation, reduced VEGF/Flt-1 protein expression, and diminished the number of TRAP⁺ cells, as well as the implanted bone resorption. Conclusion  This study demonstrated that EM inhibited VEGF and Flt-1 gene expression. The molecular mechanism of EM action on VEGF/Flt-1 signaling-mediated osteoclastogenesis warrants further investigation.