Lin Zheng-Mei, Song Zhi, Qin Wei, Li Juan, Li Wen-Jie, Zhu Hai-Yan, Zhang Li
Department of Operative and Endodontics, Sun Yat-sen College of Medical Sciences, Sun Yat-sen University, Guangzhou, China.
J Endod. 2009 Jun;35(6):838-42. doi: 10.1016/j.joen.2009.03.047.
The nucleotide-binding oligomerization domain (NOD) proteins belong to a distinct family of proteins that are implicated in the intracellular recognition of bacterial components. NOD2 appears to be a sensor of bacterial peptidoglycans because it recognizes a minimal motif present in all peptidoglycans. The interaction of NOD2 with downstream signaling molecules ultimately results in the activation of NF-kappaB and production of inflammatory mediators in innate immunity. As such, NOD2 may play an important role in the detection of bacterial pathogens and the initiation of inflammation within the dental pulp. This study was designed to evaluate the expression of NOD2 in normal human dental pulp cells (HDPCs) and human pulp tissues.
Human pulp tissue samples were collected from freshly extracted human wisdom teeth, and HDPCs were prepared from the explants of normal human dental pulp tissues. Nested reverse-transcription polymerase chain reaction (Nested RT-PCR) and Western blotting were performed to detect the expression of NOD2 messenger RNA and protein, respectively. Immunohistochemical staining was used to determine the distribution of NOD2 in the pulp tissues.
The NOD2 messenger RNA and protein were present in normal human dental pulp tissues, with most NOD2 protein expression being localized to odontoblasts and some pulp vascular endothelial cells. In contrast, HDPCs only showed a low level of NOD2 protein expression.
Our results suggest that NOD2 protein expressed in HDPCs and pulp tissues may play an important role in dental immune defense.
核苷酸结合寡聚化结构域（NOD）蛋白属于一个独特的蛋白质家族，参与细胞内对细菌成分的识别。NOD2似乎是细菌肽聚糖的感受器，因为它能识别所有肽聚糖中存在的一个最小基序。NOD2与下游信号分子的相互作用最终导致核因子κB的激活以及先天性免疫中炎症介质的产生。因此，NOD2可能在牙髓中细菌病原体的检测和炎症的引发中发挥重要作用。本研究旨在评估NOD2在正常人类牙髓细胞（HDPCs）和人类牙髓组织中的表达。
从新鲜拔除的人类智齿中收集牙髓组织样本，并从正常人类牙髓组织的外植体中制备HDPCs。分别进行巢式逆转录聚合酶链反应（Nested RT-PCR）和蛋白质印迹法检测NOD2信使核糖核酸和蛋白质的表达。免疫组织化学染色用于确定NOD2在牙髓组织中的分布。
NOD2信使核糖核酸和蛋白质存在于正常人类牙髓组织中，大多数NOD2蛋白质表达定位于成牙本质细胞和一些牙髓血管内皮细胞。相比之下，HDPCs仅显示低水平的NOD2蛋白质表达。
我们的结果表明，HDPCs和牙髓组织中表达的NOD2蛋白可能在牙齿免疫防御中发挥重要作用。
