Panagakos F S, Hinojosa L P, Kumar S
Department of Biochemistry and Molecular Biology, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark 07103.
Inflammation. 1994 Jun;18(3):267-84. doi: 10.1007/BF01534268.
Tumor necrosis factor-alpha (TNF-alpha), a 17-kDa cytokine produced by stimulated macrophages/monocytes, modulates the functions of a variety of cells and has been shown to induce bone resorption in vitro. However, the effects that TNF-alpha may have on the process of bone formation are not completely understood. In order to study the effects of TNF-alpha on matrix development and mineralization, we utilized a human osteoblastic cell line, HOS TE85. Our results show that HOS TE85, which has been shown to be responsive to hormones active on normal osteoblasts, forms an extensive extracellular matrix (ECM) that mineralizes during extended culture. Treatment during the development of the matrix with TNF-alpha has little effect on cell number and DNA synthesis, showing thereby that TNF-alpha is not cytotoxic to the cells. However, TNF-alpha inhibits the formation of alkaline phosphatase (AP)-positive foci in a dose-dependent manner at concentrations of 0.1-10 ng/ml. TNF-alpha treatment caused a significant decrease in the incorporation of collagen into the developing matrix. In addition, TNF-alpha treatment resulted in a significant decrease in the synthesis of AP by HOS TE85 cells during the process of ECM formation and resulted in a pronounced lack of mineralization of the ECM. These results indicate that TNF-alpha may be acting as an uncoupler by decreasing the synthesis and incorporation of proteins required for bone formation, and inhibiting matrix formation and mineralization in vitro.
肿瘤坏死因子-α（TNF-α）是一种由受刺激的巨噬细胞/单核细胞产生的17千道尔顿细胞因子，可调节多种细胞的功能，并且已证实在体外可诱导骨吸收。然而，TNF-α对骨形成过程可能产生的影响尚未完全明确。为了研究TNF-α对基质发育和矿化的影响，我们使用了人成骨细胞系HOS TE85。我们的结果表明，已证对作用于正常成骨细胞的激素有反应的HOS TE85，在延长培养过程中形成广泛的细胞外基质（ECM）并发生矿化。在基质发育过程中用TNF-α处理对细胞数量和DNA合成影响很小，从而表明TNF-α对细胞无细胞毒性。然而，TNF-α在0.1 - 10 ng/ml浓度下以剂量依赖性方式抑制碱性磷酸酶（AP）阳性灶的形成。TNF-α处理导致胶原蛋白掺入发育中的基质的量显著减少。此外，TNF-α处理导致在ECM形成过程中HOS TE85细胞合成AP的量显著减少，并导致ECM明显缺乏矿化。这些结果表明，TNF-α可能通过减少骨形成所需蛋白质的合成和掺入，并在体外抑制基质形成和矿化，而起到解偶联剂的作用。
