Th17/Treg免疫平衡在吸烟相关性牙周炎免疫调节及炎症损伤中作用机制的研究

Tobacco smoking is high correlated with periodontitis, but the mechanismsarenot well understood.Our previous studies demonstrated the functional expression ofneural α7 nAChRinperiodontal (non-neural) tissues. Nicotine acted directly and specifically through α7 nAChR to affect Th17/Tregbalance by stimulating the sceretion of IL1/IL6 and inducing thetransformation of Treg cells to Th17 cells, thus caused the sceretion ofIL17 and the activation of downstream immune response. Those results indicating that the Th17/Tregbalancemay play a key role in smoking retated periodontal immunoregulation and tissue inflammation. This project will adopt periodontal ligament cells and experiment periodontal rats as the model, and use receptor blocking, RNA interfering and immunol transfectionas the methodology, to investigate how the α7 nAChR regulates nicotine's effects on periodontal inflammation and tissue dectruction by destroying the Th17/Tregbalance.The present project may disclose the impotent role of Th17/Treg balance that pertinent to a better understanding of the mechanisms of smoking related periodontitis, and offer new theoretical and experimental basis for the immunological control of smoking related periodontitis.

吸烟与牙周炎密切相关，具体机制尚不明了。课题组首次发现神经元α7 nAChR在牙周（非神经）组织中功能性表达，尼古丁可特异性激活α7 nAChR促使牙周组织分泌IL1、IL6，诱导Treg细胞向Th17细胞转化，并与TGF-β共同诱导Th17细胞分化，进而促进IL17分泌释放而引发下游免疫级联反应。由此强力提示Th17/Treg 免疫平衡可能在吸烟相关性牙周炎免疫调节及炎症损伤过程中发挥重要作用。本项目将以尼古丁作用下牙周膜细胞和实验性牙周炎大鼠为模型，从受体阻断、RNA干扰等层面，采用定量PCR、细胞转染、ELISA和Transwell等分子生物学方法，深入研究尼古丁通过其受体破坏Th17/Treg免疫平衡对牙周组织产生破坏作用、促进牙周炎发生和发展的机制，并从Th17/Treg免疫平衡的新视角阐述吸烟相关性牙周炎发生、发展的相关机制，为吸烟相关性牙周炎的免疫防治提供理论基础和实验依据。

吸烟是慢性牙周炎重要危险因素，其确切作用机制不明。作为烟草中主要毒性成分，尼古丁可通过烟碱型乙酰胆碱受体（α7nAChR）促使牙周组织分泌 IL1、IL6,从而引发免疫级联反应。本研究在建立大鼠实验性牙周炎和人牙周膜成纤维细胞实验模型的基础上，采用定量 PCR、ELISA 和Transwell 等分子生物学方法，深入研究尼古丁—α7nAChR —IL-1、IL-6损伤途径与Th17/Treg 免疫平衡间的相互作用，探明尼古丁对牙周损坏的机制。体内实验证实尼古丁作用下， 实验性牙周炎大鼠的牙周组织中IL-1、IL-6表达升高。实验性牙周炎大鼠的牙周组织中可见少量IL-17阳性细胞,尼古丁作用下IL-17的阳性细胞表达增多， α-BTX可拮抗尼古丁上述作用。推测尼古丁可能刺激T细胞向TH17转化，打破Th17/Treg 免疫平衡，促进牙周炎的发生发展。体外实验证实尼古丁作用下， IL-1、IL-6表达升高，同时Th17/Treg免疫平衡被打破；选用抗体中和了IL-1、IL-6后，Th17/Treg免疫平衡无明显变化。因此，尼古丁对Th17/Treg 免疫平衡的影响可能是通过IL-1和IL-6产生作用的。