新型机械敏感离子通道Piezo参与牙本质过敏反应及损伤修复的机制研究

Dentin hypersensitivity is a prevalent disorder and one of the most annoying diseases in elderly patients, which have a negative effect on the quality of a person’s life. Recent clinically desensitizing therapies suggested for dentin hypersensitivity are mainly based on the mechanism of action and occluding dentinal tubules to disturb the transmission of nerve impulses. But the treatments are not sufficient and very successful, partly because the dentin sensory transduction mechanisms are still not clear enough. Piezo, a novel mechanically-activated cation channel, is expressed in several tissues and have been identified in odontoblast cells in 2013. Wheather the Piezo ion channel play a pivotal role in the tooth pain transmission and the in-situ formation of dentin-pulp complex is not concerned. The present project will be to check its expression and functional activity in the different periods of tooth development by realtime-PCR, fluorescence labeling and confocal laser microscopy, to test its electrophysiological characteristics and the pain signaling transduction mechaninsm in dentin hypersensitivity by three-dimensional stress loading system in vitro and dentin sensitivity model in vivo. Also, its effect on the mechanical response of the human dental pulp tissue and the reparative dentinogenesis in situ under external mechanical stimulus will be measured. The fulfillment of this project will be helpful to further enrich the key pathogenesis of dentin hypersensitivity, to reveal the dentine nociceptive transduction mechanism and the corresponding damage repair mechanisms of the pulp tissue, and will be of great importance to develop a new concept of gene treatment for dentin hypersensitivity.

牙本质过敏是困扰中老年患者的主要口腔疾患之一, 严重影响患者的生活质量。临床上常以阻塞牙本质小管为目的进行各种试验性治疗，而长期治疗效果难以保证，这源于对牙本质感觉传导的机制仍不够清楚。Piezo离子通道是2013年被证实表达于成牙本质细胞的一类新型机械敏感型离子通道，目前关于Piezo在外界刺激下牙本质敏感痛觉传导及牙髓牙本质复合体原位诱导形成的相关研究鲜有报道。本课题拟通过实时定量PCR、免疫组化、显微镜检等技术检测 Piezo通道在不同牙齿发育阶段的表达定位和功能活性；并通过体外细胞三维应力加载系统和体内牙本质敏感模型深入探讨Piezo在牙本质过敏痛觉信号转导的电生理学特性、作用机制及其对外界损伤刺激下牙髓组织细胞机械反应、修复性牙本质原位诱导形成的作用。本课题的完成将有助于进一步丰富牙本质过敏的关键致病机理，揭示牙本质敏感痛觉传导机制和牙髓相应的损伤修复机制，开拓临床治疗的新思路。

牙本质过敏是临床常见的口腔疾患之一， Piezo 通道作为一种新型的机械敏感型离子通道，可能在牙本质机械刺激感觉传导及牙齿损伤修复过程中起着重要的作用。本课题通过PCR 和免疫组化等方法检测了Piezo 通道在不同牙齿发育阶段的表达定位和功能活性，发现Piezo在牙胚发育早期无明显表达，中晚期才开始表达，且成牙本质细胞比牙髓干细胞中表达量明显高，提示成牙本质细胞是具有神经感受功能的感受器细胞，且发育早期并不具备压力感受性，仅在中晚期发育成熟后才发挥感觉传导功能。本研究还发现在大鼠牙本质暴露模型中，随着炎症的进展，piezo表达呈现一个缓慢上升的趋势，尤其是第21天时表达达到高峰，此时损伤修复因子DSPP表达也显著增加，表明牙本质出现修复，有再生牙本质形成。提示piezo可能同时参与了牙本质炎性及损伤修复过程。体外模拟机械刺激引起的牙本质敏感反应，随着力的增加，炎性相关因子先升高后降低；成牙向相关基因表达也逐渐增加，钙离子浓度也增加，说明适当的力值刺激有助于成牙本质的形成；同时随着加载力的增加，细胞内的piezo表达增高；Piezo1被沉默时，piezo2表达明显增高，这说明尽管Piezo1被干扰，但Piezo2可代偿发挥作用参与再生牙本质形成。动物体内实验表明，沉默Piezo则未见明显的牙髓牙本质样复合物形成，进一步证实piezo在牙本质牙髓复合体损伤修复中发挥着重要的作用。本课题首次提示了Piezo在牙本质机械刺激感觉传导及牙齿损伤修复过程中的作用,有利于丰富牙本质敏感的痛觉发生机制及机械刺激信号转导机理，开拓牙本质敏感治疗的新思路.