Abe Y, Kawakami A, Nakashima T, Ejima E, Fujiyama K, Kiriyama T, Ide A, Sera N, Usa T, Tominaga T, Ashizawa K, Yokoyama N, Eguchi K
The First Department of Internal Medicine, Nagasaki University School of Medicine, Japan.
J Lab Clin Med. 2000 Nov;136(5):344-54. doi: 10.1067/mlc.2000.109757.
Humoral factors produced by activated T cells are thought to be important in the development of bone loss in patients with rheumatoid arthritis (RA). We investigated the inhibitory effect of etidronate disodium (EHDP) on apoptosis of human osteoblasts induced by supernatants from in vitro activated T cell cultures. Human osteoblastic cell line MG63 cells and human primary osteoblast-like cells were used in the present study as human osteoblasts. T cells were incubated with interleukin-2 and further activated with 1 2-o-tetradecanoyl-phorbol 13-acetate and ionomycin, either in the presence or absence of EHDP. After we carried out the cultivation, we examined the cytotoxicity of cultured T cell supernatants toward MG63 cells and human primary osteoblast-like cells. Supernatants from activated but not resting T cell cultures efficiently induced apoptosis of MG63 cells and primary osteoblast-like cells. Supernatants from activated T cell cultures, incubated with EHDP, exhibited significantly less cytotoxicity than did supernatants incubated in the absence of EHDP. In contrast, the cytotoxicity of activated T cell culture supernatants was not affected by direct treatment of human osteoblasts with EHDP. The concentration of soluble Fas ligand in activated T cell culture supernatants was actually increased by EHDP. However, EHDP did not influence soluble Fas and tumor necrosis factor-alpha concentrations in the supernatant. Furthermore, treatment of human osteoblasts with EHDP did not alter their expression of Bcl-2/Bcl-xL or their sensitivity to anti-Fas immunoglobulin M-induced apoptosis. Our results suggest that EHDP inhibits the production of soluble factor that induces apoptosis of human osteoblasts and thus exhibits a protective action toward human osteoblast apoptosis induced by activated T cell culture supernatants. Although the exact EHDP-regulated molecule that induces apoptosis of human osteoblasts is unknown at present, our study may explain part of the therapeutic action of bisphosphonates in RA complicated by bone loss.
活化T细胞产生的体液因子被认为在类风湿关节炎（RA）患者骨质流失的发展过程中起重要作用。我们研究了依替膦酸二钠（EHDP）对体外活化T细胞培养上清液诱导的人成骨细胞凋亡的抑制作用。在本研究中，使用人成骨细胞系MG63细胞和人原代成骨样细胞作为人成骨细胞。T细胞与白细胞介素-2一起孵育，然后在有或没有EHDP的情况下，用12-O-十四烷酰佛波醇-13-乙酸酯和离子霉素进一步激活。培养后，我们检测了培养的T细胞上清液对MG63细胞和人原代成骨样细胞的细胞毒性。活化但非静止的T细胞培养上清液能有效诱导MG63细胞和原代成骨样细胞凋亡。与未添加EHDP孵育的上清液相比，添加EHDP孵育的活化T细胞培养上清液的细胞毒性显著降低。相反，EHDP直接处理人成骨细胞对活化T细胞培养上清液的细胞毒性没有影响。EHDP实际上增加了活化T细胞培养上清液中可溶性Fas配体的浓度。然而，EHDP对上清液中可溶性Fas和肿瘤坏死因子-α的浓度没有影响。此外，用EHDP处理人成骨细胞并没有改变其Bcl-2/Bcl-xL的表达或其对抗Fas免疫球蛋白M诱导凋亡的敏感性。我们的结果表明，EHDP抑制了诱导人成骨细胞凋亡的可溶性因子的产生，从而对活化T细胞培养上清液诱导的人成骨细胞凋亡具有保护作用。尽管目前尚不清楚确切的受EHDP调节的诱导人成骨细胞凋亡的分子，但我们的研究可能解释了双膦酸盐在并发骨质流失的RA中的部分治疗作用。
