口腔扁平苔藓中Treg细胞功能缺失机制及其修复应用基础研究

Oral lichen planus(OLP) is a T cell-mediated immune-related disease. The etiology and pathogenesis of OLP have not been well elucidated. It has been well known that Treg cells are the main regulator to maintain immune tolerance, thus manipulating Treg cells is a promising strategy to treat autoimmune diseases and immune-related diseases. According to the results of our previous studies, we found the frequency of Treg cells was negatively correlated with T cell activation in subepithelial lymphocytic infiltrate of the OLP lesion. However, dysfunction of Treg cells also happened in OLP lesions. This finding suggest manipulating Treg cells might be a new therapeutic strategy to treat and prevent OLP. The following studies are designed to prove the hypothesis: (1) Changes of the activation markers and function markers of Treg cells in the clinical samples of OLP, and then find the molecular mechanisms of Treg cell dysfunction; (2) Based on the molecular mechanisms of Treg cell dysfunction, stimulate or modulate Treg cells to correct the defects of Treg cells, and then check the suppression function; (3) Investigate the inflammation of the oral mucosal in deficient mice models of Treg cell related genes, double check the functions of Treg cells in oral mucosal immune balance, evaluate the possibility of manipulating Treg cells to treat OLP. The result of this research will shed a new light on the mechanism of Treg cell dysfunction in the pathogenesis of OLP, thus facilitate the development of new therapeutic strategies to treat and prevent OLP and other chronic immune-related diseases.

免疫治疗是当前的研究热点（Science 2013）。调节Treg细胞的功能从而治疗自身免疫性疾病，具有诱人前景（Nat Rev Immunol 2015）。基于申请人前期发现的Treg细胞在口腔扁平苔藓（OLP）病损局部功能出现缺陷的结果，本课题假定，修复OLP中Treg细胞的功能，具有治疗OLP的潜力。为验证此假说，本课题拟整合临床队列、基因缺陷小鼠和体外细胞模型研究，采用独创的黏膜超微量淋巴细胞分离等新技术，观察：① OLP 患者Treg 细胞表面活化标记物的表达变化、功能变化及其机制；②刺激、修复OLP患者Treg细胞的抑制功能，评价其作为OLP治疗新靶点的可行性；③基因缺陷小鼠模型验证Treg细胞与口腔炎症病变的关系。本项目成果不仅有助于阐明Treg细胞功能缺失与OLP发生的关系，更重要的是，利用OLP作为观测模型，进一步阐明Treg细胞作为免疫相关疾病防治新靶点的可能与潜力。

口腔扁平苔藓是一种主要由T淋巴细胞介导的慢性特发炎症性口腔粘膜疾病。CD4+CD25+Foxp3+调节性T细胞（Treg细胞）是抑制自身免疫性炎症、维持自身免疫稳态最重要的免疫细胞亚群，其在治疗自身免疫性疾病和慢性炎症性疾病方面具有巨大的应用前景。本课题研究发现：（1）OLP患者病损局部微环境中的Treg 细胞的IL-2-CD25信号通路下调，导致Treg细胞的功能出现耗竭，提示IL-2-CD25信号通路是特异性修复和增强OLP病损局部Treg细胞的抑制功能的潜在靶点；（2）通过加入IL-2等因子在体外培养、刺激、扩增炎性环境来源的Treg 细胞可以恢复其免疫抑制功能，并使Treg细胞大量分裂增殖，使通过增强自身Treg细胞的功能治疗OLP等炎症性疾病成为可能；（3）Il2基因敲除小鼠和Foxp3基因敲除小鼠等Treg细胞相关基因敲除小鼠模型中，基因敲除小鼠的口腔粘膜发生严重的炎细胞浸润，导致口腔粘膜出现了明显的病理性改变，进一步验证了Treg细胞在口腔免疫稳态中的重要作用；（4）使用T细胞过继转移模型，可以构建口腔粘膜慢性炎症病变模型，向此小鼠模型中同时输注Treg细胞，可以抑制口腔粘膜炎症的发展。不仅如此，我们还进一步在其他成熟的自身免疫性疾病小鼠模型中，证明了本课题建立的刺激和扩增Treg细胞的方法在治疗多种炎症性疾病中的潜在应用前景。综上所述，本课题研究证明，通过刺激IL-2-CD25信号通路培养、刺激和增强Treg细胞的功能，是OLP等口腔粘膜炎症性疾病的潜在免疫治疗手段。