骨保护素抑制肿瘤坏死因子诱导的成骨细胞凋亡(英文)

Inhibitory effect of osteoprotegerin on tumor necrosis factor-induced apoptosis in osteoblastic cells

背景:骨质疏松涉及破骨细胞分化成熟和成骨类细胞凋亡两方面,肿瘤坏死因子α能诱导多种细胞凋亡且效率差异很大,骨保护素能抑制破骨细胞成熟,但对成骨类细胞凋亡的作用未见报道。目的:探讨肿瘤坏死因子α能否诱导成骨类细胞凋亡及骨保护素能否抑制其凋亡。设计:以成骨细胞和MG63细胞作为实验对象、以鼠WEHI164细胞系用于阳性对照的观察对比分析。单位:解放军总医院全军口腔医学研究所、美国匹茨堡医学院退伍军人医疗中心。材料:本实验于2001-01/2003-12在Dr.Blair实验室和口腔研究所实验室完成。选择商品化细胞系,RPMI1640培养液和各种相关蛋白用于实验。方法:用人间充质干细胞在分化培养液中培养21d使之成为成骨细胞,与MG63一起用于凋亡实验。AnnexinV和原位末端标记法检测肿瘤坏死因子α诱导成骨类细胞凋亡。主要观察指标:全部细胞数及凋亡细胞数。结果:和FasL诱导细胞凋亡一样,肿瘤坏死因子α能引起MG63骨肉瘤细胞,间充质干细胞和成骨细胞的凋亡,并表现为明显的浓度依赖和时间依赖。低浓度肿瘤坏死因子α(170～500pmol/L)作用于细胞2～4h就显示了较明显的凋亡,而骨保护素在0.45～1.5nmol/L浓度时,几乎完全抑制了500pmol/L肿瘤坏死因子α诱导的凋亡。成骨细胞分泌骨保护素,而破骨细胞及破骨前体细胞产生肿瘤坏死因子α,它们相互作用降低成骨细胞的凋亡。结论:肿瘤坏死因子α能诱导成骨类细胞凋亡,骨保护素能够抑制肿瘤坏死因子α的凋亡诱导作用,从抑制破骨细胞成熟和成骨细胞凋亡两方面表现骨保护素防治骨质疏松的作用机制。

BACKGROUND:Osteoporosis involves two aspects,osteoblast apoptosis and osteoclast differentiation and maturation.The apoptotic effect of tumor necrosis factor α varies in different cell lines and it remains unclear whether osteoprotegerin has inhibitory effects on the apoptosis of osteoblastic cells.OBJECTIVE:To study the interaction between tumor necrosis factor α and osteoprotegerin on the apoptosis of osteoblastic cells.DESIGN:Observational comparative study based osteoblasts and MG63 cells as subjects and murine WEHI 164 cells as positive controls.SETTING:Institute of Oral Medicine,General Hospital of Chinese PLA,and Veterans' Affairs Medical Center,Pittsburgh.MATERIALS:The experiment was conducted in the Dr.Blair's Laboratory and Oral Institute from January 2001 to December 2003.Commercial cell group,RPMI 1 640 culture medium and various related proteins were selected in this study.METHODS:Osteoblasts were differentiated from human mesenchymal stem cells in the culture medium,and were ready for the study on apoptosis with MG63.Annexin V and TUNEL analysis were used to assay osteoblasts' apoptosis induced by tumor necrosis factor α .MAIN OUTCOME MEASURES:The number of total cells and apoptotic cells.RESULTS:As FasL induced apoptosis,tumor necrosis factor α could obviously induce the apoptosis of MG63 osteogenic cells,mesenchymal stem cells and osteoblasts in concentration and time dependent manner.Cells showed obvious apoptosis after 2- 4 hours' effect by tumor necrosis factor α in low concentration(170- 500 pmol/L);osteoprotegerin,on the other hand,at 0.45- 1.5 nmol/L inhibited the apoptosis induced by tumor necrosis factor α of 500 pmol/L.Osteoblasts could secrete osteoprotegerin,whereas osteoclasts and precursor of osteoclasts could produce tumor necrosis factor α and work together to reduce the apoptosis of osteoblasts.CONCLUSION:Tumor necrosis factor α can effectively induce the apoptosis of osteoblastic cells while osteoprotegerin has the ability to inhibit it.The mechanism of osteoprotegerin on osteoporosis involves at least two aspects,by inhibiting the maturation of osteoclasts and the apoptosis of osteoblasts.