目的

探讨人牙髓组织和成牙本质细胞中Toll 样受体4（TLR4）的表达与分布特点，及其在牙髓组织天然免疫防御中的可能作用。

方法

从新鲜拔除的人第三磨牙获取牙髓组织和成牙本质细胞， 扫描电镜观察牙髓摘除后髓腔壁成牙本质细胞形态和附着情况；RT-PCR 检测人牙髓组织以及成牙本质细胞中TLR4mRNA 的表达情况； 采用免疫印迹技术和免疫组织化学方法检测TLR4 蛋白的表达与定位。

结果

扫描电镜观察牙髓摘除后成牙本质细胞大部存留在髓室壁上，细胞形态良好；RT-PCR 结果发现健康牙髓、成牙本质细胞均可表达TLR4mRNA，产物大小为278 bp；免疫印迹法检测正常牙髓、成牙本质细胞在相对分子质量89 000 附近出现蛋白条带；免疫组化显示牙髓组织中的成牙本质细胞、血管内皮细胞TLR4 免疫反应阳性。 正常牙髓中牙髓成纤维细胞不表达TLR4。

结论

成牙本质细胞通过表达TLR4 参与牙髓牙本质复合体的先天免疫反应，TLR4 在牙髓抵御外来病原微生物入侵的宿主免疫防御中起重要作用。

Objective

To investigate the expression and distribution of Toll like receptor 4（TLR4） in human dental pulp tissue and odontoblasts and explore the role of TLR4 in the innate immune response.

Methods

Odontoblasts and pulp tissue were collected from extracted human teeth. Scanning electron microscopy （SEM） was performed on representative teeth to demonstrate the existence of an odontoblast monolayer. TLR4 mRNA levels of human pulp tissue and odontoblasts were assayed by reverse transcriptionpolymerse chain reaction （RT-PCR）.The expression and localization of TLR4 protein were studied with western blot and immunohistochemistry.

Results

SEM revealed the integrity of the odontoblast layer and the well-preserved morphology of the individual cells.RT-PCR demonstrated TLR4 mRNA expression in odontoblasts and healthy pulp tissue with a 278bp transcript. Western blot with TLR4-specific antibody also detected the 89 000 protein in these samples. Immunohistochemical staining detected TLR4 in odontoblasts in the dental pulp. Negative immunostaining was observed in the pulp fibroblasts. Some pulp capillary endothelial cell exhibited intense staining.

Conclusions

Human odontoblasts and pulp tissue express TLR4， which suggests that odontoblasts take part in the innate immune systerm and TLR4 may play an important role in the host defense of human dental pulp.