Autocrine stimulation of osteoblast activity by Wnt5a in response to TNF-α in human mesenchymal stem cells
Autocrine stimulation of osteoblast activity by Wnt5a in response to TNF-α in human mesenchymal stem cells
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DOI：
10.1016/j.bbrc.2012.12.036
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发表时间：
2013-01-18
影响因子：
3.1
通讯作者：
Magne, D.
中科院分区：
文献类型：
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作者：
Briolay, A.;Lencel, P.;Magne, D.
虽然抗肿瘤坏死因子（TNF）-α治疗有效地阻断了强直性脊柱炎（AS）的炎症，但它们对防止过度骨形成无效。在AS中，骨化似乎更倾向于在抗TNF治疗后炎症消退的部位发展，这表明TNF-α间接刺激骨化。在这种情况下，我们的目标是确定和比较参与Wnt蛋白，这是骨形成的有效生长因子，在TNF-α对成骨细胞功能的影响。在人类间充质干细胞（MSC）中，TNF-α显著增加了Wnt 10 b和Wnt 5a的水平。与此相关，TNF-α刺激组织非特异性碱性磷酸酶（TNAP）和矿化。通过用抗Dkk 1抗体、氯化锂（LiCl）或SB 216763激活经典β-连环蛋白途径来模拟这种效应。TNF-α减少，β-连环蛋白的激活对成骨细胞分化的晚期标志物骨钙素的表达几乎没有影响。令人惊讶的是，TNF-α不能稳定β-连环蛋白，Dkk 1也不能抑制TNF-α的作用。事实上，Dkk 1的表达也在对TNF-α的反应中增强，这也许解释了为什么Wnt 10 b的经典信号传导没有被TNF-α激活。然而，我们发现Wnt 5a也刺激成骨条件下培养的MSC中的TNAP，并增加炎症标志物如考克斯-2的水平。有趣的是，用抗Wnt 5a抗体处理降低了内源性TNAP表达和活性。总的来说，这些数据表明，Dkk 1水平的增加可能会减弱Wnt 10 b的自分泌作用，但不会减弱Wnt 5a的自分泌作用，这是通过非经典信号传导起作用的。因此，Wnt 5a可能参与炎症对骨形成的影响。(C)2012 Elsevier Inc. All rights reserved.
Although anti-tumor necrosis factor (TNF)-alpha treatments efficiently block inflammation in ankylosing spondylitis (AS), they are inefficient to prevent excessive bone formation. In AS, ossification seems more prone to develop in sites where inflammation has resolved following anti-TNF therapy, suggesting that TNF-alpha indirectly stimulates ossification. In this context, our objectives were to determine and compare the involvement of Wnt proteins, which are potent growth factors of bone formation, in the effects of TNF-alpha on osteoblast function. In human mesenchymal stem cells (MSCs), TNF-alpha significantly increased the levels of Wnt10b and Wnt5a. Associated with this effect, TNF-alpha stimulated tissue-non specific alkaline phosphatase (TNAP) and mineralization. This effect was mimicked by activation of the canonical beta-catenin pathway with either anti-Dkk1 antibodies, lithium chloride (LiCl) or SB216763. TNF-alpha reduced, and activation of beta-catenin had little effect on expression of osteocalcin, a late marker of osteoblast differentiation. Surprisingly, TNF-alpha failed to stabilize beta-catenin and Dkk1 did not inhibit TNF-alpha effects. In fact, Dkk1 expression was also enhanced in response to TNF-alpha, perhaps explaining why canonical signaling by Wnt10b was not activated by TNF-alpha. However, we found that Wnt5a also stimulated TNAP in MSCs cultured in osteogenic conditions, and increased the levels of inflammatory markers such as COX-2. Interestingly, treatment with anti-Wnt5a antibodies reduced endogenous TNAP expression and activity. Collectively, these data suggest that increased levels of Dkk1 may blunt the autocrine effects of Wnt10b, but not that of Wnt5a, acting through non-canonical signaling. Thus, Wnt5a may be potentially involved in the effects of inflammation on bone formation. (C) 2012 Elsevier Inc. All rights reserved.