Li Chenghua, Li Bei, Dong Zhiwei, Gao Li, He Xiaoning, Liao Li, Hu Chenghu, Wang Qintao, Jin Yan
Stem Cell Res Ther. 2014 May 27;5(3):67. doi: 10.1186/scrt456.
Periodontitis is initiated and sustained by bacteria. However, the mechanism of bacteria induced periodontitis is still unknown. We hypothesized that bacterial components can affect the functions of stem cells in the periodontium. In this study, we comparatively investigated the influence of Lipopolysaccharide (LPS) on the osteogenesis potential of human periodontal ligament stem cells (PDLSCs) and bone marrow mesenchymal stem cells (BMMSCs).
Human PDLSCs and BMMSCs were harvested and mineralized nodule formation was assessed by alizarin red S staining. Expression level of osteogenic related gene was detected by quantitative RT-PCR (qRT-PCR). The expression of Toll-like receptor 4 (TLR4) and its downstream signaling pathway were examined by western blot. The role of TLR4 and related signaling pathway in LPS impairing the osteogenic potential of human PDLSCs and BMMSCs were also studied by alizarin red S staining and qRT-PCR. Experimental periodontitis was induced in adult Sprague-Dawley rats and the alveolar bone loss was measured by micro computed tomography analysis. The expression of alkaline phosphatase (ALP) was assessed by immunohistochemistry and the number of osteoclasts was shown by Tartrate-resistant acid phosphatase (TRAP) staining.
LPS decreased the osteogenic differentiation of human PDLSCs through TLR4 regulated nuclear factor (NF)-κB pathway, but not for BMMSCs. Blocking TLR4 or NF-κB signaling partially reversed the decreased osteogenic potential of PDLSCs and prevented the alveolar bone loss caused by LPS experimental periodontitis in rats. The ALP expression in the periodontal ligament was elevated after treatment with anti-TLR4 antibody or pyrrolidinedithiocarbamate, whereas there was no statistical significance among groups for the number of osteoclasts.
These data suggest that LPS can activate TLR4 regulated NF-κB pathway of human PDLSCs, thus decreasing their osteogenic potential. Blockage of TLR4 or NF-κB pathway might provide a new approach for periodontitis treatment.
牙周炎由细菌引发并持续存在。然而，细菌诱发牙周炎的机制仍不明确。我们推测细菌成分会影响牙周组织中干细胞的功能。在本研究中，我们比较研究了脂多糖（LPS）对人牙周膜干细胞（PDLSCs）和成人间充质干细胞（BMMSCs）成骨潜能的影响。
获取人PDLSCs和BMMSCs，通过茜素红S染色评估矿化结节形成情况。采用定量逆转录聚合酶链反应（qRT-PCR）检测成骨相关基因的表达水平。通过蛋白质免疫印迹法检测Toll样受体4（TLR4）及其下游信号通路的表达。还通过茜素红S染色和qRT-PCR研究了TLR4及相关信号通路在LPS损害人PDLSCs和BMMSCs成骨潜能中的作用。对成年Sprague-Dawley大鼠诱导实验性牙周炎，通过微型计算机断层扫描分析测量牙槽骨吸收情况。通过免疫组织化学评估碱性磷酸酶（ALP）的表达，用抗酒石酸酸性磷酸酶（TRAP）染色显示破骨细胞数量。
LPS通过TLR4调节的核因子（NF）-κB途径降低人PDLSCs的成骨分化，但对BMMSCs无此作用。阻断TLR4或NF-κB信号通路可部分逆转PDLSCs降低的成骨潜能，并预防LPS实验性牙周炎所致大鼠牙槽骨吸收。用抗TLR4抗体或吡咯烷二硫代氨基甲酸盐处理后，牙周膜中ALP表达升高，而各组间破骨细胞数量无统计学差异。
这些数据表明LPS可激活人PDLSCs的TLR4调节的NF-κB途径，从而降低其成骨潜能。阻断TLR4或NF-κB途径可能为牙周炎治疗提供新方法。
