Musculoskeletal Research Group and Tumour Biology, Chair of Vegetative Anatomy, Faculty of Medicine, Institute of Anatomy, Ludwig-Maximilian-University Munich, Pettenkoferstrasse 11, 80336, Munich, Germany.
Biomedical Center, Core facility animal models, Ludwig-Maximilian-University Munich, 82152, Martinsried, Germany.
Cell Tissue Res. 2020 Jul;381(1):83-98. doi: 10.1007/s00441-020-03188-8. Epub 2020 Mar 6.
It has been established that inflammation plays an important role in bone formation and bone loss. Although a lot is known about the role of TNF-α in bone health, very little is understood about TNF-β, also called lymphotoxin. In this report, we examine the effect of TNF-β on osteogenic differentiation of mesenchymal stem cells (MSCs) and its modulation by resveratrol. Monolayer and high-density cultures of MSCs were treated with osteogenic induction medium with/without TNF-β, Sirt1 inhibitor nicotinamide (NAM), antisense oligonucleotides against Sirt1 (ASO) and/or Sirt1 stimulator resveratrol. We found that TNF-β inhibits, in a similar way to NAM or Sirt1-ASO, the early stage of osteogenic differentiation of MSCs and this was accompanied with downregulation of bone-specific matrix, β1-integrin, Runx2 and with upregulation of NF-κB phosphorylation and NF-κB-regulated gene products involved in the inflammatory, degradative processes and apoptosis. However, resveratrol reversed TNF-β- and NAM-suppressed MSCs osteogenesis by activation of Sirt1 and Runx2 that led to osteoblast differentiation. Furthermore, downregulation of Sirt1 by mRNA inhibited the effect of resveratrol, highlighting the important impact of this enzyme in the TNF-β signaling pathway. Finally, resveratrol was able to manifest its effect both by suppression of TNF-β-induced NF-κB and through direct activation of the Sirt1 and Runx2 pathway. Thus, through these studies, we present a mechanism by which a T cell-derived cytokine, TNF-β can affect bone formation through modulation of MSCs differentiation that involves NF-κB, Sirt1, Runx2 and resveratrol reversed TNF-β-promoted impairments in MSCs osteogenesis.
已经证实，炎症在骨形成和骨丢失中发挥重要作用。尽管人们对 TNF-α 在骨骼健康中的作用有了很多了解，但对 TNF-β（也称为淋巴毒素）知之甚少。在本报告中，我们研究了 TNF-β 对间充质干细胞（MSCs）成骨分化的影响及其被白藜芦醇调节的情况。用成骨诱导培养基处理单层和高密度培养的 MSCs，有/没有 TNF-β、Sirt1 抑制剂烟酰胺（NAM）、Sirt1 反义寡核苷酸（ASO）和/或 Sirt1 激动剂白藜芦醇。我们发现，TNF-β 以类似于 NAM 或 Sirt1-ASO 的方式抑制 MSCs 成骨分化的早期阶段，这伴随着骨特异性基质、β1-整合素、Runx2 的下调，以及 NF-κB 磷酸化和 NF-κB 调节的参与炎症、降解过程和细胞凋亡的基因产物的上调。然而，白藜芦醇通过激活 Sirt1 和 Runx2 逆转了 TNF-β 和 NAM 抑制的 MSCs 成骨作用，导致成骨细胞分化。此外，通过 mRNA 下调 Sirt1 抑制了白藜芦醇的作用，突出了该酶在 TNF-β 信号通路中的重要影响。最后，白藜芦醇能够通过抑制 TNF-β 诱导的 NF-κB 发挥作用，并且通过直接激活 Sirt1 和 Runx2 途径发挥作用。因此，通过这些研究，我们提出了一种机制，即 T 细胞衍生的细胞因子 TNF-β 可以通过调节 MSCs 分化来影响骨形成，这涉及 NF-κB、Sirt1、Runx2 和白藜芦醇逆转 TNF-β 促进的 MSCs 成骨损伤。
