IFN-gamma-producing human T cells directly induce osteoclastogenesis from human monocytes via the expression of RANKL

The current study explored our hypothesis that IFN-gamma-producing human T cells inhibit human osteoclast formation. Activated T cells derived from human PBMC were divided into IFN-gamma-producing T cells (IFN-gamma(+) T cells) and IFN-gamma-non-producing T cells (IFN-gamma(-) T cells). IFN-gamma(+) T cells were cultured with human monocytes in the presence of macrophage-CSF alone. The concentration of soluble receptor activator of NF-kappaB ligand (RANKL) and IFN-gamma, and the amount of membrane type RANKL expressed on T cells, were measured by ELISA. In the patients with early rheumatoid arthritis (RA) treated with non-steroidal anti-inflammatory drugs alone, CD4+ T cells expressing both IFN-gamma and RANKL were detected by flow cytometry. Surprisingly, IFN-gamma(+) T cells, but not IFN-gamma(-) T cells, induced osteoclastogenesis from monocytes, which was completely inhibited by adding osteoprotegerin and increased by adding anti-IFN-gamma antibodies. The levels of both soluble and membrane type RANKL were elevated in IFN-gamma(+) T cells. The ratio of CD4+ T cells expressing both IFN-gamma and RANKL in total CD4+ T cells from PBMC was elevated in RA patients. Contrary to our hypothesis, IFN-gamma(+) human T cells induced osteoclastogenesis through the expression of RANKL, suggesting that Th1 cells play a direct role in bone resorption in Th1 dominant diseases such as RA.     

破骨细胞骨吸收的分子机制

破骨细胞性骨吸收是在骨的微环境内进行的复杂分子生物学反应过程,涉及到众多蛋白质和调控因子的参与。有关破骨细胞的活化,骨基质的吸收,骨吸收的调控等方面,现有的数据还不够充分。本文综述了金属基质蛋白酶(M atrix m eta lloprote inases,MM P s)在破骨细胞移行和骨基质吸收方面的重要作用,以及破骨细胞分化因子(R eceptor activator of NF-κB-ligand,RANKL)和护骨素(O steoprotegerin,OPG)在骨吸收调控网络中的地位。     

力学载荷对破骨细胞凋亡的影响及其调节机制

破骨细胞是参与骨代谢的基本功能细胞之一.破骨细胞在骨重建过程中主要承担旧骨组织的破坏和吸收,因此,破骨细胞凋亡的微小变化都可能会改变骨重建的进程.调节破骨细胞凋亡的因素有很多,如雌激素、二磷酸盐等生物化学因素,但力学载荷对于破骨细胞生物学活性影响的研究相对较少.综述了力学载荷对破骨细胞生物学活性的影响以及细胞凋亡与破骨细胞凋亡的调节.     

雷公藤甲素通过抑制破骨细胞生成预防骨丢失的研究

目的 探讨雷公藤甲素抗骨质疏松的作用及机制。方法 建立大鼠老年性骨质疏松模型。40只22月龄雄性SD大鼠随机分为雷公藤甲素（每天15μg/kg腹腔注射）治疗组和生理盐水对照组（每天15μg/kg腹腔注射）,连续8周。采用显微CT分析胫骨近端骨松质的骨密度(BMD)和骨显微结构。WB检测成骨相关蛋白表达水平。TRACP-5b染色法测定破骨细胞数,同时检测骨吸收标志物表达水平。结果 显微CT结果显示,雷公藤甲素治疗组大鼠骨密度、骨体积/总体积比值(Bv/Tv)、骨小梁厚度(Tb.Th)、骨小梁数目(Tb.N)、骨小梁间距(Tb.Sp)均显著高于对照组（P<0.05）。两组的成骨相关蛋白表达水平无明显差异,TRACP-5b染色显示雷公藤甲素减少了体内破骨细胞的数量（P<0.05）,同时血液骨吸收标志物水平也明显降低（P<0.05）。结论 雷公藤甲素通过抑制破骨细胞生成进而对老年性骨质疏松有保护作用。雷公藤甲素可能是治疗老年性骨质疏松症的一种可行方案。     

Piezo1介导的机械应力刺激在抗骨质疏松中的作用

背景：机械敏感通道蛋白Piezo1是机械应力刺激的重要靶蛋白,能将物理的机械力转化成生物电信号,从而调控骨形成与骨吸收,在抗骨质疏松中发挥着重要作用。目的：总结机械应力刺激在抗骨质疏松中的作用机制、Piezo1分子生物学研究进程及Piezo1在骨质疏松中的研究进展。方法：使用计算机在中国知网、万方、维普、Pub Med及Web of Science数据库进行文献检索,中文检索词为“骨质疏松、Piezo1、机械应力、骨”,英文检索词为“osteoporosis,Piezo1,mechanical,osteoblast,osteoclast,chondrocyte,bone”,根据纳排标准对文献进行筛选,最终纳入65篇文献进行综述。结果与结论：(1)机械敏感通道蛋白Piezo1的蛋白结构在冷冻电镜技术突破中不断得到新的解析,目前研究表明Piezo1蛋白基于三叶螺旋桨状三维构造主体,在静默和应激状态下可表现出不同的结构变化;(2)Piezo1介导的机械应力刺激能通过调控成骨细胞、软骨细胞、内皮细胞、肠道细胞的功能影响骨形成,同时调控破骨细胞的功能影响骨吸收,进而在抗骨质疏松中发挥重要作用;(...     

Rat Osteoclast Precursors In Vivo Express a Vitronectin Receptor and a Chloride-Bicarbonate Exchanger

In vivo osteoclast precursors, which are mononuclear, were previously found to express TRAP (tartrate-resistant acid phosphatase) and CTR (calcitonin receptor), like multi-nucleated osteoclasts. In vitro, they were found to express, in addition, VNR (vitronectin receptor) and CBE (chloride-bicarbonate exchanger). In order to ascertain that osteoclast precursors in vivo express VNR and CBE like their in vitro counterparts, we used immunohistochemistry to localize these molecules in developing long bones of neonatal rats. Frozen sections of metatarsals and phalanges of 1-2 day-old rats were stained for TRAP and mineralization using histochemistry or were reacted with polyclonal antibodies specific for either the β₃ chain of the VNR or synthetic sequences of the CBE. Both mature, multinucleated osteoclasts within the forming marrow cavity of metatarsals (as shown previously) and mononuclear osteoclast precursors located outside the bony collar of the phalangeal calcified rudiment (as shown here for the first time) expressed both TRAP, VNR and CBE. These findings suggest that mononuclear osteoclast precursors express many of the phenotypical markers of multinucleated osteoclasts prior to their fusion and multinucleation which may allow them to resorb bone, as suggested by in vitro observations of pit formation by preosteoclasts cultured on resorbable substances.     

Placenta Hominis Protects Osteoporosis in Ovariectomized Rats

In China, Japan, and Korea, placenta hominis extracts (PHEs) are used clinically for the treatment of osteoporosis. The anti-osteoporotic effect of PHEs was studied. The trabecular bone area and thickness in OVX rats decreased by 50% from those in sham-operated rats; these decreases were completely inhibited by administration of PHEs for 7 weeks. Osteoclast numbers and the osteoblast surface were enhanced in OVX rats, but PHEs had no effect on these phenomena. Serum phosphorus and alkaline phosphatase in OVX rats increased compared to those in sham-operated rats, but the increases were not affected by the administration of PHEs. Thyroxine (T₄) level was stimulated in OVX rats. The extracts inhibited the T₄ level in the OVX rats. These results strongly suggest that PHEs be effective in preventing the development of bone loss induced by OVX in rats.     

False-Positive β-Galactosidase Staining in Osteoclasts by Endogenous Enzyme: Studies in Neonatal and Month-Old Wild-Type Mice

Escherichia coli β-galactosidase (β-gal), encoded by the lacZ gene, has become an essential tool in studies of gene expression and function in higher eukaryotes. lac-Z is widely used as a marker gene to detect expression of transgenes or Cre recombinase driven by tissue-specific promoters. The timing and location of promoter activity is easily visualized in whole embryos or specific tissues using the cleavable, chromogenic substrate, 5-bromo-4-chloro-3-indolyl-D-galactopyranoside (X-gal). The tissue specificity of promoters in transgenic constructs is routinely tested by using a promoter of choice to drive lacZ. Alternatively, the targeted expression of Cre recombinase to perform in vivo recombination of loxP sites can be visualized by β-gal staining in mice carrying a Cre-activated lacZ transgene, such as the ROSA26 strain. In the course of our investigations, we examined β-gal activity in bone tissue from genetically normal mice using standard detection methodology and found very high endogenous activity in bone-resorbing osteoclasts. This was true in frozen, paraffin, and glycol methacrylate sections. X-gal staining colocalized with the osteoclast marker, tartrate-resistant acid phosphatase (TRAP). β-gal activity was present in osteoclasts in long bones, in the mandible, and in both neonatal and more mature animals. We present this brief article as a caution to those testing genetic models of skeletal gene expression using β-gal as a marker gene.     

钛颗粒负荷对成骨细胞释放细胞因子的影响

假体周围的溶骨性因子是造成无菌性松动的主要原因之一。前期的研究表明,磨损颗粒抑制成骨细胞分化和矿化能力,为探索不同直径的磨损颗粒对成骨细胞释放细胞因子的影响,我们采用双夹心抗体ELISA、RT-PCR法分析3种直径钛颗粒对兔成骨细胞表达IL-6I、L-10和破骨细胞分化因子(ODF)的影响。结果显示:0.9μm钛颗粒刺激成骨细胞产生大量促骨吸收因子(IL-6、ODF)的同时快速而短暂地释放抑骨吸收因子(IL-10);2.7μm和6.9μm钛颗粒,尤其是后者主要是刺激成骨细胞缓慢而强烈地产生促骨吸收因子。提示:磨屑颗粒作用成骨细胞的生物学反应是双相的,且反应程度因颗粒大小和作用时间的不同而又有所不同。可见如何抑制假体周围溶骨性因子的产生以及人工材料的优化选择是提高人工假体寿命的关键。     

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。