树突状细胞靶向重组乳酸菌抗H1N1亚型流感病毒黏膜免疫分子机制研究

Mucosal immunization is one of the most important immune routines in immunology, especially gut mucosal immunization. Dendritic cells (DC) provide a first line of defense following influenza virus infection; however, the mechanisms of DC in mucosal immunity are not fully elucidated. A strategy will be established utilizing Lactobacillus to deliver the protective antigen (HA) of H1N1 subtype influenza virus via specific dendritic cell-targeting peptides (DCpep) to DC residing in the submucosal layers of intestinal tract, thus directing and regulating acquired immunity. The effect of DC in oral delivery of Lactobacillus was evaluated on the T helper cells, regulatory T cells, and cytokines in mucosal immunity. Collectively, development of this strategy for oral delivery of DC-targeted antigens maybe reveal the mechanisms of DC in priming and regulating mucosal immunity in order to provide a theoretical basis of strengthening and controlling the vaccination via the mucosal route.

黏膜免疫是当前免疫学领域的研究热点，尤其是肠道黏膜免疫越来越受人们重视。树突状细胞是抵御流感病毒感染的第一道防线，然而其参与黏膜免疫的机制尚不完全清楚。本研究以树突状细胞（DC）的靶向配体-DCpep修饰H1N1亚型流感病毒的保护性抗原-HA，构建融合表达HA-DCpep的重组基因工程乳酸菌。借助乳酸菌的黏附特性，将表达的HA靶向提呈给DC，以此介导肠道DC提呈抗原的靶向效应，进而引发有效的抗原特异性免疫应答。通过体内外试验，以DC、辅助性T细胞、调节性T细胞及黏膜免疫相关细胞因子为研究靶点，在细胞水平和分子水平上探讨DC增强黏膜免疫效果的机制。该研究的意义在于揭示重组乳酸菌在激发黏膜免疫反应过程中，黏膜组织DC启动和调控黏膜免疫应答的机制，为加强和控制黏膜途径免疫接种提供理论基础。

黏膜免疫是当前免疫学领域的研究热点，尤其是肠道黏膜免疫越来越受人们重视。树突状细胞（DCs）在引发固有免疫和介导获得性免疫中发挥重要作用，然而其参与黏膜免疫的机制尚不完全清楚。靶向免疫是提高疫苗免疫效率的一种有效策略。本研究以植物乳杆菌作为抗原递呈载体，将DCs靶向肽（DCpep）与流感病毒的HA蛋白进行融合表达，构建了靶向DCs的口服黏膜免疫疫苗Lp-HA-DCpep。通过体内外试验，以DC、Th及黏膜免疫相关细胞因子为研究靶点，在细胞水平和分子水平上探讨DCs增强黏膜免疫效果的机制。结果显示Lp-HA-DCpep通过TLR4—NF-κB路径激活DCs，并借助CCR7-CCL19/CCL21轴促进DCs迁移，而提高了抗原向T和B淋巴细胞的递呈功能，促使Th细胞向Th1、Th2和Treg细胞极化，引发有效的黏膜和获得性免疫应答，由此能够有效地抵御流感病毒的感染。该靶向递呈口服黏膜疫苗的构建为今后抗流感口服疫苗的设计提供了一个新的策略。该研究的意义在于初步揭示了黏膜组织DCs启动和调控黏膜免疫应答的机制，为加强和控制黏膜途径免疫接种提供理论基础。