水产品原肌球蛋白致敏性评价新型细胞模型的建立

With the internationalization of food trade and the development of modern food industry, food allergy has become an important food safety problem both in china and abroad. The accurately evaluation of the allergenicity of food allergens is the primary task for controlling allergies. Existing studies have shown that food allergens are processed and presented into T lymphocytes by dendritic cells in body, and help B lymphocytes produce IgE antibodies, then produce allergic symptoms. In this study, the tropomyosin of aquatic products, as the research object, with the characteristics of high similarity of amino acid sequence and different sensitization, was used to established animal model and parse the T cell epitope with combination of the bioinformatics methods. The relationship between degradation products and T cell epitopes was passed by analyzing the degradation of dendritic cell endoplasmic reticulum. On this basis, the binding ability of the degradation products to the surface receptors of T cells was investigated, and the differentiation of T cells to Th2 cells under the action of degradation products was further clarified, and the relationship between the sensitization of the tropomyosin of aquatic products was then discussed. Combined with the existing cell model for food allergenic evaluation, a new model would be established based on the T cell changes in food allergenic process to provide technical support for controlling the risk of food allergy.

随着食品贸易的国际化和现代食品工业的发展，食品过敏已经成为国内外重要的食品安全问题，对食品过敏原的致敏性进行准确评价成为控制过敏风险的首要任务。现有研究表明，食品过敏原进入机体后被树突细胞加工后递呈到T淋巴细胞，并辅助B淋巴细胞产生IgE抗体，进而产生过敏症状。本课题拟以水产品原肌球蛋白为研究对象，利用其氨基酸序列相似度高而致敏性差异大的特点，建立针对不同水产品原肌球蛋白的动物模型，结合生物信息学手段解析其T细胞表位；分析不同水产品中原肌球蛋白在树突细胞内质网中的降解规律，解析降解产物与T细胞表位的关系；在此基础上探讨降解产物与T细胞表面受体的结合能力，并进一步明确在降解产物作用下T细胞向Th2细胞分化的规律，揭示水产品原肌球蛋白致敏性与T细胞识别的关系；结合已有的食品过敏原致敏性评价细胞模型，构建基于致敏过程中T细胞变化的过敏原致敏性新型评价模型，为控制食品过敏风险提供技术支撑。

水产品原肌球蛋白（TM）类具有氨基酸序列高度相似而致敏性差异大的特点。本课题以鱼-TM，虾-TM和贝-TM为主要研究对象，分析三种蛋白的结构，IgG/IgE结合能力，建立不同的小鼠过敏模型并与RBL-2H3细胞模型进行对比分析，探究其对T淋巴细胞的分化能力并通过蛋白组学分析其潜在的生物标志物，并结合生物信息学技术解析其B细胞表位和T细胞表位，探讨不同水产品TM在树突状细胞中的降解规律，解析降解产物与T细胞表位之间的关系。结果表明，鱼-TM，虾-TM和贝-TM三种蛋白的结构差异性较小，其中虾-TM和贝-TM的IgG/IgE结合能力和脱颗粒能力相似，而鱼-TM的IgG/IgE结合能力和脱颗粒能力较弱，虾-TM和贝-TM能够促进Th2型细胞因子分泌，抑制Th1型细胞因子分泌，而鱼-TM相反。蛋白组学结果表明，脾脏中固有免疫蛋白（Cochlin）和适应性免疫蛋白（Ig k chain V-III region PC 7175）可以作为Th1/Th2型分化的生物标志物。通过生物信息学软件预测并鉴定了虾-TM的三个B细胞表位（B1: 47–61, QKRMQQLENDLDQVQ; B2: 97–108, EDLERSEERLNT 和B3: 244–257, RSVQKLQKEVDRLE）和一个T细胞表位（VQESLLKANIQLVEK, 60−74）。不同水产品TM在树突状细胞中加工降解产物差别较大，其中虾-TM在敏化的BMDC中加工降解的多肽中含有T细胞表位和B细胞表位。综上所述，本项目系统的分析了不同水产品原肌球蛋白致敏性差异的原因，解释了树突细胞中加工降解的多肽与细胞表位之间的关系，构建了小鼠T淋巴细胞评价模型，为控制食物过敏风险提供了理论基础和技术支持。