BACKGROUND Appropriate mechanical stimulation is essential for bone homeostasis in healthy periodontal tissues. While the osteogenesis and osteoclast differentiation of inflammatory periodontal ligament cells under different dynamic loading has not been yet clear. The aim of this study is to clarify the inflammatory, osteogenic and pro-osteoclastic effects of different cyclic stress loading on the inflammatory human periodontal ligament cells (hPDLCs). METHODS hPDLCs were isolated from healthy premolars and cultured in alpha minimum Eagle's medium (α-MEM). Lipopolysaccharides (LPS) were used to induce the inflammation state of hPDLCs in vitro. Determination of LPS concentration for the model of inflammatory periodontium was based on MTT and genes expression analysis. Then the cyclic stress of 0, 0-50, 0-90 and 0-150 kPa was applied to the inflammatory hPDLCs for 5 days respectively. mRNA and protein levels of osteogenic, osteoclastic and inflammation-related markers were examined after the treatment. RESULTS MTT and RT-PCR results showed that 10 μg/ml LPS up-regulated TNF-α, IL-1β, IL-6, IL-8 and MCP-1 mRNA levels (P < 0.05) and did not affect the cell viability (P > 0.05). The excessive loading of stress (150 kPa) with or without LPS strongly increased the expression of inflammatory-related markers TNF-α, IL-1β, IL-6, IL-8, MCP-1 (P < 0.05) and osteoclastic markers RANKL, M-CSF, PTHLH and CTSK compared with other groups (P < 0.05), but had no significant effect on osteogenic genes. While 0-90 kPa cyclic pressure could up-regulate the expression of osteogenic genes ALP, COL-1, RUNX2, OCN, OPN and OSX in the healthy hPDLSCs. CONCLUSIONS Collectively, it could be concluded that 0-150 kPa was an excessive stress loading which accelerated both inflammatory and osteoclastic effects, while 0-90 kPa may be a positive factor for the osteogenic differentiation of hPDLCs in vitro.

中文翻译：

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根据加载力，循环压缩对脂多糖诱导的炎症性人牙周膜细胞的成骨和破骨状态产生双重影响。

背景技术适当的机械刺激对于健康的牙周组织中的骨稳态是必不可少的。虽然在不同的动态负荷下炎性牙周膜细胞的成骨和破骨细胞分化尚不清楚。这项研究的目的是阐明不同循环应力负荷对人类炎性牙周膜细胞（hPDLC）的炎性，成骨性和破骨前作用。方法从健康的前磨牙中分离出hPDLC，并在α最小Eagle培养基（α-MEM）中进行培养。脂多糖（LPS）用于体外诱导hPDLC的炎症状态。基于MTT和基因表达分析确定炎性牙周模型的LPS浓度。然后是0、0-50，将0-90和0-150kPa分别施加于炎性hPDLC 5天。治疗后检查成骨，破骨细胞和炎症相关标志物的mRNA和蛋白水平。结果MTT和RT-PCR结果显示10μg/ ml LPS上调TNF-α，IL-1β，IL-6，IL-8和MCP-1 mRNA水平（P <0.05），并且不影响细胞活力（P＞ 0.05）。有或没有LPS的压力过大（150 kPa）都强烈增加了炎症相关标记TNF-α，IL-1β，IL-6，IL-8，MCP-1和破骨细胞标记RANKL的表达（P <0.05） ，M-CSF，PTHLH和CTSK与其他组相比（P <0.05），但对成骨基因没有显着影响。0-90 kPa循环压力可以上调健康hPDLSCs中成骨基因ALP，COL-1，RUNX2，OCN，OPN和OSX的表达。