白血病抑制因子对牙本质发育的影响

Influence of LIF on Dentin Development in Mice

目的:探究白血病抑制因子(leukemia inhibitory factor, LIF)对牙本质发育的影响。方法:免疫组织化学染色观察LIF在出生后2天(post-natal 2,PN2)小鼠成牙本质细胞中的表达。建立小鼠切牙机械损伤模型,统计切牙生长速率;通过微计算机断层扫描技术(micro computed tomography, Micro-CT)、显微硬度计、电子探针测量Lif-/-小鼠及其对照切牙的牙本质密度、硬度及钙磷比(Ca/P);碱性磷酸酶(ALP)染色和茜素红染色观察LIF对成牙本质细胞矿化的影响;免疫荧光染色观察成牙本质细胞Ⅰ型胶原α1(Col1α1)、牙本质基质蛋白1(DMP1)表达情况。结果:LIF随着成牙本质细胞分化程度增加表达含量升高。Lif-/-小鼠切牙新生速率减慢。Lif-/-小鼠切牙近釉牙本质界侧牙本质密度、硬度及Ca/P均降低。ALP及茜素红染色结果显示Lif敲低的成牙本质细胞ALP水平降低、矿化结节数量减少,而加入LIF外源性刺激后可以逆转这一现象。免疫荧光结果显示Lif-/-小鼠成牙本质细胞Col1α1、DMP1表达含量降低。结论:LIF缺失抑制小鼠牙齿牙本质形成与矿化。

Objective:To investigate the effect of LIF during dentin formation.Methods:Immunohistochemistry(IHC)was employed to detect the expression pattern of LIF during odontoblast differentiation in PN2 incisors.About 2mm from the tip of the erupted part of the left incisor of each mouse was removed to compare different growth speed between Lif-/-group and the control group.The mandibles were scanned by a micro-computed tomography(Micro-CT)instrument.Mimics was used to analyze the mineral density of dentin in both groups.Microhardness measurement was carried out to measure the dentin surface hardness.Electron probe X-ray microanalyser(EPMA)was performed for surface elements analysis of mandibular incisors.Immunofluorescence(IF)was employed to detect the expression of Col1α1 and DMP1 in odontoblasts.Results:LIF was present in polarizing odontoblasts,and gradually increased with the mature of odontoblasts.The growth speed of Lif-/-incisors were slower than that of control group.The mineral density and Vickers hardness of dentin in Lif-/-incisors were lower than that in wildtype mice.The element atomic percent of the Ca/P ratio was reduced in Lif-/-mice.Knockdown of Lif decreased the ALP activity and the formation of mineralized matrix nodules and these could be rescued by adding LIF.The expressions of Col1α1 and DMP1 were decreased in odontoblasts of Lif-/-group.Conclusion:Deficiency of LIF restrains the formation and mineralization of incisor dentin in mice.