群体感应信号分子farnesol通过STING-TBK1-IRF3信号通路调控阴道上皮细胞抗真菌的免疫应答

Recalcitrant recurrence and biofilm infections are one of the clinical problems of vulvovaginal candidiasis (VVC). At present, studies on the immunological mechanism of VVC have shifted the focus on the innate immune response of the vaginal epithelial cells (VEC), while its exact function and regulating mechanisms have not been elucidated. Recently, we have found that quorum sensing molecule farnesol could not only suppress fungal hyphae formation and adhesion, biofilm formation, but also could enhance vaginal innate immune response, upregulating Stimulator of interferon gene (STING). We speculate farnesol may regulate the VEC antifungal immune response via innate immune response related STING-TBK1-IRF3 signaling pathway, indirectly mediating the adaptive immune response. Based on the previous study, we plan to use RNA interference or overexpression technologies, cell culture system and animal models, analyzing the expression of downstream key factors and target effector molecules of STING-type I interferon (IFN-α/β), further revealing the role of farnesol and STING signaling pathway in vaginal local immune responses, providing a new theoretical basis for the application of farnesol and STING-TBK1-IRF3 signal pathway in female microecology.

外阴阴道假丝酵母菌病(VVC)的顽固复发与真菌生物膜感染是临床难题之一。目前国内外对VVC免疫学机制的研究已转移至阴道上皮细胞(VEC)的固有免疫应答，具体机制尚未完全阐明。近期我们研究发现，真菌群体感应信号分子farnesol除了能抑制真菌粘附、菌丝及生物膜的形成外，还能增强阴道固有免疫应答，上调干扰素基因刺激蛋白(STING)的表达，推测farnesol可能通过固有免疫应答STING-TBK1-IRF3信号通路调控VEC抗真菌的免疫应答，间接调控适应性免疫应答。本项目拟在此基础上深入研究，采用RNA干扰或过表达技术等，利用细胞培养系统或模型动物，分析STING上下游因子及靶效应分子I型干扰素(IFN-α/β)表达变化，进一步分析farnesol及STING通路在阴道局部免疫应答中的作用及机制，为farnesol及STING-TBK1-IRF3信号通路在女性微生态领域中的应用提供新思路。

本项目成功建立STING(+)VK2/E6E7过表达细胞模型，证明STING过表达后，其上下游的cGAS、TBK、IRK3、IFN-α及IFN-β均高表达，功能学研究证实STING过表达后，孢子对VK2/E6E7的粘附作用降低，刺激Th1类、Th2类及Th17类细胞因子的分泌，真菌增殖活力降低，死亡真菌数显著增加。成功建立STING(-)VK2/E6E7感染细胞模型后再加入farnesol治疗，证实STING在farnesol抗真菌活性中发挥关键作用，敲低STING后，farnesol的抗真菌及促进免疫应答的活性显著降低，说明farnesol主要通过STING/ TBK/IRK3信号通路来发挥其抗真菌及免疫“佐剂”的作用，farnesol可能作为STING的潜在agonist。大鼠动物模型实验证实farnesol能够降低大鼠阴道内的真菌负荷，增加大鼠阴道壁内STING、ILs、IFN-α及IFN-β的表达，降低线粒体肿胀，从而缓解阴道炎症状。