Th17细胞在口腔念珠菌病中的作用及机制研究

The Th17 cells and IL-17 receptor signaling are essential for mucosal host defense. It might serve as the cross roads of innate and adaptive immunity against infectious disease of mucosa. Oral candidiasis is the most common opportunistic fungal infection in oral cavity, the rational of limited superficial characterization suggested that there might exist special mechanisms of oral immunity. This study aims to the Th17 cells and IL-23/Il-17 pathway, combined with our previous study on local antimicrobial peptides, including the defensins and histatins, to explore their expression in sera, saliva and tissue if available, as well as the IL-17 mRNA level, and to investigate the possible signaling pathway among patients with oral candidiasis by case control study and in vitro, using the techniques as candida species isolation and identification, primary oral epithelial cell culture, the BioPlex Suspension Array System, RT-PCR and ELispot, and the in vitro cultured oral epithelial cell would be applied for observation the IL-17's role on adherence of candida albicans on the surface of oral epithelial cells. These researches will help us to understand the role of Th17 cells and IL-17 in the oral immunity against candida infection, and to understand whether the IL-17 has the function to regulate the local mucosal immunity, such as defensins, histatins which are important antimicrobial peptide in oral epithelium. The result of this study would benefit the understanding for host-infection mechanism of oral candidiasis, and deliver new hints for future strategy for treatment of oral candiasis.

Th17细胞被认为在粘膜抗感染免疫中起着重要作用，可能是沟通获得性免疫与天然免疫的重要因素。口腔念珠菌病是最常见的口腔真菌机会感染，其局限浅表感染的特点提示口腔粘膜可能具有特别的防御机制。本研究以Th17细胞以及相关IL-23/IL-17轴信号通路为研究切入点，结合本课题组防御素等抗菌肽在口腔局部抗感染免疫研究的主线，通过病例对照研究及体外研究相结合，利用微生物培养分离鉴定技术，结合细胞培养、液相悬浮芯片系统、RT-PCR、ELISPot等方法从蛋白表达水平及mRNA转录水平等对Th17细胞和IL-23/IL-17轴在口腔念珠菌病中的作用及相关调控机制进行研究，同时深入分析其与口腔粘膜局部防御素的关系，并通过体外细胞培养技术探讨IL-17等是否对念珠菌环境下口腔黏膜上皮防御素等抗菌肽的表达有调控作用，是否影响念珠菌对口腔黏膜上皮细胞的粘附，以揭示Th17细胞在口腔黏膜抗真菌感染中的作用。

口腔上皮免疫是口腔抗感染的重要方面。在前期研究基础上，动态监测了HAART治疗中HIV/AIDS患者发现口腔表征出现率呈下降趋势，口腔念珠菌负荷、病毒载量和IL-4 呈下降趋势，同时免疫情况改善。主要包括外周血 CD4+T 淋巴细胞计数升高、 IFN-γ， IL-17(A/F)均呈上升趋势，Th1→Th2漂移现象有所缓解，Tc1/Tc2比值接近1:1，但是IL-23、 HBD2变化未发现明显规律性。研究发现EOLP患者唾液IL-1β、IL-6、hBD-2、hBD-3水平及口腔念珠菌负荷显著高于健康对照组，hBD-2水平与IFN-γ呈正相关、与IL-17呈负相关，hBD-3水平与IL-17和IL-10均呈负相关。异基因造血干细胞移植（allogeneic hematopoietic stem cell transplantation，Allo-HSCT）术后，有口腔cGVHD组相较于无口腔cGVHD组，血清IL-4、IL-6、IL-10、IL-23水平均升高，TGF-β水平下降；IL-6、IL-23与TGF-β水平呈负相关关系，口腔表征计分与IL-6、IL-23水平呈正相关关系，与TGF-β水平呈负相关关系。白血病组内口腔cGVHD患相较于健康对照组，其血清IL-4、IL-6、IL-10水平升高；唾液IL-6、IL-10水平升高。此外，白血病组中cGVHD患者口腔表征计分与唾液IL-6水平呈正相关关系。体外实验中发现， IL-17能明显促进口腔粘膜上皮细胞hBD-2分泌，随着IL-17对细胞刺激时间的延长，hBD-2分泌量增加，此外，IL-17可以减少白色念珠菌对细胞的黏附率，提示IL-17可能通过促进hBD-2的分泌发挥抗感染作用。. 故本研究发现， Th17细胞及其相关细胞因子与防御素密切相关，且在口腔粘膜抗感染免疫中起着重要作用，是沟通获得性免疫与天然免疫的桥梁，为进一步给口腔念珠菌病的免疫治疗提供了理论依据。