Induction of apoptosis in chondrocytes by tumor necrosis factor-alpha
Induction of apoptosis in chondrocytes by tumor necrosis factor-alpha
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DOI：
10.1016/s0736-0266(00)00078-4
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发表时间：
2001-09-01
影响因子：
2.8
通讯作者：
Gerstenfeld, LC
中科院分区：
文献类型：
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作者：
Aizawa, T;Kon, T;Gerstenfeld, LC
肿瘤坏死因子α（TNF-α）诱导许多细胞类型的凋亡，并在骨重建中起重要作用，既刺激成骨细胞的增殖又激活破骨细胞。在软骨内骨化过程中，软骨细胞凋亡与新骨形成和吸收以及矿化软骨被编织骨替代同时发生。在本研究中，检查了TNF-α在促进软骨细胞凋亡中的作用。分别从17天鸡胚胸骨的头部和尾部分离富含肥大细胞或非肥大细胞的软骨细胞群，并在体外用0.1-10 nM重组人TNF-α处理。作为阳性对照，Fas受体抗体结合也诱导凋亡。细胞活/死比率的染料排除测定显示，TNF-α引起肥大和非肥大软骨细胞中死细胞数量的剂量依赖性1.5倍和2.0倍增加。通过测量白细胞介素-1 β转化酶（ICE）活性独立测定细胞凋亡的诱导，并通过半定量测定DNA片段化进行分析。当与未处理的细胞相比时，这些分析还显示在两种软骨细胞群中TNF-α诱导的凋亡的剂量依赖性增加，对于所有剂量的TNF-α，ICE活性水平增加（从近似5倍到近似20倍）。然而，成骨细胞不受TNF-α治疗或Fas抗体/蛋白G诱导的影响。软骨细胞Fas受体和caspase-2蛋白表达的免疫染色显示，用TNF-α处理后，大多数软骨细胞表达这两种凋亡标志物。尽管在更肥大的细胞中细胞杀伤和ICE诱导更高，但TNF-α在肥大和非肥大软骨细胞群体中诱导细胞凋亡。这些结果表明，细胞凋亡可以通过Fas和TNF-α受体介导的信号传导在肥大和非肥大软骨细胞中诱导。并提示软骨细胞比成骨细胞对骨骼谱系中TNF-α的凋亡作用更敏感。(C)2001骨科研究学会。由爱思唯尔科技有限公司出版。保留所有权利。
Tumor necrosis factor alpha (TNF-alpha) induces apoptosis in a number of cell types and plays an essential role in bone remodeling, both stimulating the proliferation of osteoblasts and activating osteoclasts. During endochondral ossification, apoptosis of chondrocytes occurs concurrently with new bone formation and the resorption and replacement of mineralized cartilage with woven bone. In the present study, the role of TNF-alpha in promoting chondrocyte apoptosis was examined. Chondrocyte cell populations, enriched in either hypertrophic or non-hypertrophic cells, were isolated from the cephalic and caudal portions of 17-day chick embryo sterna, respectively, and treated in vitro with 0.1-10 nM recombinant human TNF-alpha. As a positive control, apoptosis was also induced by Fas receptor antibody binding. Dye exclusion assays of the live/dead ratios of cells showed that TNF-alpha caused a dose-dependent 1.5- and 2.0-fold increase in the number of dead cells in both hypertrophic and non-hypertrophic chondrocytes. Induction of apoptosis was independently assayed by measurement of interleukin-1 beta -converting enzyme (ICE) activity, and analyzed by a semi-quantitative determination of DNA fragmentation. When compared to untreated cells, these analyses also showed dose-dependent increases in TNF-alpha induced apoptosis in both chondrocyte populations, with increases in the levels of ICE activity for all doses of TNF-alpha (from similar to5 to similar to 20 fold). Osteoblasts, however, were not affected by treatment with TNF-alpha or by Fas antibody/protein G induction. Immunostaining of chondrocytes for Fas receptor and caspase-2 protein expression showed that most of the chondrocytes expressed these two markers of apoptosis after treatment with TNF-alpha. Although cell killing and ICE induction were higher in the more hypertrophic cells, TNF-alpha induced apoptosis in both hypertrophic and non-hypertrophic chondrocyte populations, These results demonstrate that apoptosis may be induced in both hypertrophic and non-hypertrophic chondrocytes through both Fas and TNF-alpha receptor mediated signaling, and suggest that chondrocytes are more sensitive to apoptotic effects of TNF-alpha within the skeletal lineage than are osteoblasts. (C) 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.