1,25-二羟维生素D3靶向VEGF调控哮喘气道上皮屏障的作用及其机制

The airway epithelial barrier plays a crucial role in allergic sensitisation. Disruption of the epithelial barrier may facilitate transport of allergens to allergen-presenting cells and promote pro-in?ammatory cytokines activities of the epithelium. Therefore epithelial barrier function serves as an important target for future therapeutic strategies in asthma. Vitamin D has an important role on the immune system and its regulation of mucosal immunity has been recognized recently.VEGF also plays an important role in enhancing respiratory allergen sensitization and Th2 in?ammation..In our previous study,we have found that house dust mite (HDM) allergens and common occupational asthma sensitizer TDI can both increase airway epithelial permeability and VEGF expression, and vitamin D pretreatment can significantly inhibit the change of permeability and VEGF expression induced by HDM and TDI at the same time. This indicates that vitamin D can protect airway epithelial barrier function,and its mechanism may be related to the regulation of VEGF expression..This study will further confirm the protection function of vitamin D on epithelial barrier under the conditions of HDM/TDI or asthma serum for passive sensitization in vitro. Then we explore the role of PI3K/VEGF and vitamin D receptor(VDR) pathway during this process using siRNA technology and pathway inhibitors. Meanwhile we develop asthma model based on airway VDR knockout mice to deep explore the possible mechanism of PI3K/VEGF and VDR in this process through testing epithelial permeability and inflammation indexes.The project aims to clarify the role and the possible mechanism of vitamin D on airway epithelial barrier,and provide new perspective for prophylaxis and treatment of asthma.

气道上皮屏障功能的损伤在哮喘气道炎症的启动中至关重要。近年维生素 D在粘膜免疫中的调节作用成为关注热点，而VEGF在哮喘过敏原致敏及Th2气道炎症中亦扮演重要角色。本课题组发现：维生素D能够降低被HDM及常见职业性哮喘致敏物TDI刺激引起的气道上皮高通透性，并抑制致敏物诱导气道上皮高表达的VEGF。这提示维生素 D对气道上皮屏障功能具有保护作用，其机制与调控VEGF有关。本研究拟通过体外HDM/TDI及哮喘血清被动致敏分别作用气道上皮细胞，验证维生素D对上皮屏障的保护作用。采用siRNA、通路抑制等技术，观测PI3K/VEGF及VDR在维生素D影响上皮屏障中的作用。同时利用气道VDR基因敲除小鼠，建立小鼠哮喘模型，检测上皮通透性和炎症指标，深入研究PI3K/VEGF和VDR在此过程中的相关机制。本项目旨在探讨维生素D对气道上皮屏障功能的保护及可能机制，为哮喘防治提供新视点。

研究背景及目的.气道粘膜屏障功能损伤在哮喘气道炎症的启动和维持中发挥重要作用，但其确切调控机制尚不清楚。维生素D除了调节钙和骨代谢，还发挥重要的免疫调节作用，VEGF作为Th2炎症关键介质受到研究关注。本课题主要目标探讨Vitamin D对屋尘螨及TDI等诱导的气道上皮损伤的保护作用及进一步探讨如何通过影响VEGF通路发挥屏障保护功能。.重要结果及关键数据：.（1）临床研究：1、维生素D水平与哮喘表型相关性研究；2、哮喘患者低血清维生素D水平与抑郁状态相关。.（2）体外实验.1、首次证明了25羟维生素D3（非活性维生素D）对支气管上皮细胞的影响可能并非通过上调气道上皮ZO-1且并非依赖于VDR的表达及转位；2、首次发现E钙粘蛋白重分布在TDI哮喘发病过程中起重要作用，非活性维生素D可以降低16HBE VEGF的表达，对TDI诱导的16HBE VEGF的表达和释放均具有抑制作用；3、VEGF经PI3K/AKT及JNK通路破坏气道上皮屏障功能；4、维生素D下调HDM诱导的气道上皮细胞TSLP释放；5、1,25-二羟维生素D3经VEGF途径修复屋尘螨所导致的气道上皮屏障破坏；6、1,25-二羟维生素D3经ERK/calpain-1途径对香烟提取物导致的气道上皮屏障功能破坏的保护作用。.（3）动物实验：1、成功建立TDI职业相关哮喘模型；2、1,25(OH)2D3 可抑制TDI哮喘模型支气管上皮屏障蛋白的降解及重分布，保护支气管上皮屏障功能。此作用可能通过抑制ERK通路磷酸化实现。3、VEGF拮抗剂可以显著减少HDM哮喘模型气道炎症，降低屏障破坏。.科学意义 共发表SCI论文10篇，国内核心期刊论著3篇，综述1篇。会议论文7篇。发表后国际期引用8次。