Competence Center for Periodontal Research, University Clinic of Dentistry, Medical University of Vienna, Sensengasse 2a, 1090 Vienna, Austria.
Division of Orthodontics, University Clinic of Dentistry, Medical University of Vienna, Sensengasse 2a, 1090 Vienna, Austria.
Cells. 2020 Dec 16;9(12):2696. doi: 10.3390/cells9122696.
Transplanted mesenchymal stem/stromal cells (MSCs) are a promising and innovative approach in regenerative medicine. Their regenerative potential is partly based upon their immunomodulatory activities. One of the most investigated immunomediators in MSCs, such as in periodontal ligament-derived MSCs (hPDLSCs), is indoleamine-2,3-dioxygenase-1 (IDO-1) which is upregulated by inflammatory stimuli, like cytokines. However, there are no data concerning continuing IDO-1 expression in hPDLSCs after the removal of inflammatory stimuli, such as cytokines and toll-like receptor (TLR) agonist-2 and TLR-3. Hence, primary hPDLSCs were stimulated with interleukin (IL)-1β, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, TLR-2 agonist Pam3CSK4 or TLR-3 agonist Poly I/C. IDO-1 gene and protein expression and its enzymatic activity were measured up to five days after removing any stimuli. IL-1β- and TNF-α-induced IDO-1 expression and enzymatic activity decreased in a time-dependent manner after cessation of stimulation. IFN-γ caused a long-lasting effect on IDO-1 up to five days after removing IFN-γ. Both, TLR-2 and TLR-3 agonists induced a significant increase in IDO-1 gene expression, but only TLR-3 agonist induced significantly higher IDO-1 protein expression and enzymatic activity in conditioned media (CM). IDO-1 activity of Poly I/C- and Pam3CSK4-treated hPDLSCs was higher at one day after removal of stimuli than immediately after stimulation and declined to basal levels after five days. Among all tested stimuli, only IFN-γ was able to induce long-lasting IDO-1 expression and activity in hPDLSCs. The high plasticity of IDO-1 expression and its enzymatic activity in hPDLSCs due to the variable cytokine and virulence factor milieu and the temporal-dependent responsiveness of hPDLSCs may cause a highly dynamic potential of hPDLSCs to modulate immune responses in periodontal tissues.
移植的间充质干细胞（MSCs）是再生医学中一种有前途和创新的方法。它们的再生潜力部分基于其免疫调节活性。在牙周韧带来源的间充质干细胞（hPDLSCs）等 MSC 中，研究最多的免疫调节剂之一是吲哚胺 2,3-双加氧酶-1（IDO-1），它受炎症刺激物（如细胞因子）上调。然而，在去除炎症刺激物（如细胞因子和 Toll 样受体（TLR）激动剂-2 和 TLR-3）后，hPDLSCs 中 IDO-1 的持续表达数据尚不清楚。因此，原代 hPDLSCs 用白细胞介素（IL）-1β、肿瘤坏死因子（TNF）-α、干扰素（IFN）-γ、TLR-2 激动剂 Pam3CSK4 或 TLR-3 激动剂 Poly I/C 刺激。在去除任何刺激物后，测量 IDO-1 基因和蛋白质表达及其酶活性，直至第 5 天。在停止刺激后，IL-1β 和 TNF-α诱导的 IDO-1 表达和酶活性呈时间依赖性下降。IFN-γ 在去除 IFN-γ 后长达 5 天对 IDO-1 有持久影响。TLR-2 和 TLR-3 激动剂均导致 IDO-1 基因表达显著增加，但只有 TLR-3 激动剂诱导条件培养基（CM）中 IDO-1 蛋白表达和酶活性显著增加。Poly I/C 和 Pam3CSK4 处理的 hPDLSCs 在去除刺激后 1 天的 IDO-1 活性高于刺激后立即的活性，5 天后降至基础水平。在所有测试的刺激物中，只有 IFN-γ 能够诱导 hPDLSCs 中持久的 IDO-1 表达和活性。由于可变的细胞因子和毒力因子环境以及 hPDLSCs 的时间依赖性反应性，hPDLSCs 中 IDO-1 表达和酶活性的高可塑性可能导致 hPDLSCs 在牙周组织中调节免疫反应的高度动态潜力。
