THBP上调热休克蛋白90介导的树突状细胞交叉递呈和抑制哮喘Th2免疫机制的研究

哮喘是树突状细胞（DC）介导的以Th2优势免疫为特征的气道炎症性疾病。DC经MHC Ⅰ类途径交叉递呈外源性抗原，诱导CD8+细胞毒性T淋巴细胞（CTL）反应。然而，抗原特异性CTL抑制变应性炎症。热休克蛋白90（HSP90）在交叉递呈中起关键作用。申请者从白木香叶制备了一种新型天然化合物2-O-α-L-鼠李糖-4, 6, 4′-三羟基二苯甲酮（THBP），后者可与HSP90 N端特异性结合，并具有激素样抗炎作用、无激素样免疫抑制副作用。内皮穿越模型模是迄今唯一模拟单核细胞迁移分化为DC的体外诱导体系。申请者将进一步剖析THBP与HSP90结合的分子结构模式；在建立体外交叉递呈实验、体内DC清除实验、哮喘血清单核细胞内皮穿越模型基础上，阐明THBP上调HSP90介导的DC交叉递呈、诱导保护性CTL和抑制哮喘Th2免疫的机制，探讨干预Th2优势免疫的新途径，有望为将来免疫治疗哮喘提供新的方法。

Asthma is a airway inflammatory disorder characterized by dendritic cell (DC)-mediated Th2-biased immunity. The presentation of exogenous antigen on MHC class Ⅰ molecules, known as cross-presentation, is essential for the initiation of CD8+ cytotoxic T lymphocyte (CTL) responses. However, antigen-specific CTL has a protective role on allergic airway inflammation. Heat shock protein 90 (HSP90) is essential for cross-presentation of antigen by DC. We have isolated a novel natural compound, 2-O-α-rhacopyranosyl-4, 6, 4′-trihydroxy benzophenone (THBP), from the leaves of Aquilaria sinensis. Also, we identified a specific binding between THBP and N-terminal of HSP90, and a steroid-like anti-inflammatory action without immunosuppressive side effects of steroids. To date, the transendothelial trafficking model exclusively mimics the human monocyte-derived DC (MDDC) differentiation in vivo. Here we sought to: (1) further analyze the molecular structure of THBP in combination with HSP90; and (2) investigate the mechanisms regarding upregulation of HSP90-mediated DC cross-presentation by THBP, induction of protective CTL, and suppression of Th2 immunity in asthma using in vitro cross-presentation assay, DC elimination assay in vivo, and asthmatic serum-stimulated MDDC differentiation in transendothelial trafficking model. Taken together, this project is very meaningful to explore new avenues for harnessing the Th2-predominant immunity, and will provide novel strategies for future immunotherapy of asthma.