Hsp70提高罗非鱼腹腔巨噬细胞抗原呈递功能的作用机理

Hitherto, how to induce the efficient mucosal immune responses is one of the most difficult academic points in the development of fish vaccines, and the fish macrophages　 have been shown are one of the most important cells during the antigen phagocytosis and presentation processs in the fish mucosal immunity. We preseumed that tilapia heat shock protein 70 (Hsp70) may play essential roles on the mucosal immunity and the breaks of oral tolerance of tilapia, based on our previous results that tilapia Hsp70 significantly increased the phagocytosis ability against Streptococcus agalactiae antigen and the immune responses of tilapia, and the fact that Hsp70 plays a supporting role on the breaks of oral tolerance during the tumor immunity. To verify this hypothesis, the inner connection between the heterogeneity of tilapia macrophages and the stimulations of Hsp70 and /or S. agalactiae antigens are going to be investigated, followed by the experiments aim to figure out the essential roles of Hsp70 on the processs of phagocytosis and presentation of S. agalactiae antigens in the macrophages of tilapia through researches such as the dynamics of MHC-II in macrophages,expression of surface protein,cellular localization and antigen presentation.Then the transcriptome information of the tilapia macrophages with and without treatment of Hsp70 combined with S. agalactiae antigens are acquired by the Illumine Solexa methods. On the other hand, the expression profiles of antigen presentation-related genes in the peritoneal macrophages are measured during the Hsp70-mediated antigen presentation process by Northern blotting and Western blotting methods after the achievement of genome information, followed by the identification of 2 to 3 signal transmission-related genes by co-immunoprecipitation, RNAi and immunohistochemistry techniques. This project investigates the mechanisms of tilapia Hsp70 mediaed antigen phagocytosis and presentation in different subtypes of peritoneal macrophages of tilapia at both cellular and molecular levels. The success of which may provide the fundamental theory for the development of the oral vaccine against tilapia S. agalactiae.

高效诱导黏膜免疫应答是鱼类疫苗研究的重点。巨噬细胞（MΦ）是鱼类粘膜免疫系统中直接参与抗原呈递和免疫应答的重要细胞。项目组前期发现HspP70可显著提高罗非鱼MΦ链球菌抗原吞噬及免疫应答诱导能力，结合Hsp70可协助抗原有效突破肿瘤免疫耐受这一成果，提出"tHsp70可增强罗非鱼MΦ呈递链球菌抗原能力，进而可能在突破口服免疫耐受作用上发挥重要作用"的科学假说。课题通过形态观察、细胞化学和生物活性等研究分析不同亚型MΦ功能与Hsp70的关系。重点通过对不同亚型MΦ与Hsp70作用的动力学、表面分子表达、细胞定位和抗原呈递功能等的研究阐明Hsp70对MΦ抗原呈递功能的重要作用；在获得Hsp70与MΦ作用前后大量与抗原呈递相关转录组序列信息的基础上，采用免疫共沉淀及RNAi等技术鉴定2-3个关键信号传导分子。本项目探讨Hsp70提高MΦ呈递链球菌抗原的作用机制，为研究链球菌口服疫苗奠定基础。

巨噬细胞是鱼类粘膜免疫系统中直接参与抗原呈递和免疫应答的重要细胞。我们的前期研究结果发现HSP70可显著提高罗非鱼巨噬细胞链球菌抗原吞噬及免疫应答诱导能力，结合HSP70 可协助抗原有效突破肿瘤免疫耐受这一成果，提出“tHSP70 可增强罗非鱼巨噬细胞呈递链球菌抗原能力，进而可能在突破口服免疫耐受作用上发挥重要作用”的科学假说。因此，我们从分离培养罗非鱼腹腔巨噬细胞入手，对该类巨噬细胞的形态、细胞化学和生物活性等进行了研究，获得了永生化巨噬细胞系。在获得高质量低外毒素HSP70蛋白的基础上，对HSP70与链球菌抗原与巨噬细胞相互作用过程mRNA，lncRNA，DNA甲基化及蛋白质谱的变化规律进行了探究，发现差异性mRNA与lncRNA、mRNA与蛋白间存在相互调控关系，且在此过程中有显著差异性DNA甲基化修饰现象。同时发现与代谢、吞噬、抗原呈递和MCH复合体相关的通路被大量富集，表明这些富集的mRNA，lncRNA和蛋白在这些通路中发挥重要作用。利用CHIP-seq及RNAi等技术鉴定了P2X4R 、LNC_000768及其他10个与抗原呈递密切相关的信号传导分子。本课题为罗非鱼腹腔巨噬细胞呈递链球菌抗原的作用机制提供了数据支撑和理论解释，为后续更加深入阐述鱼类相关机制提供了理论依据和新的思路。