基于亲和力的罗非鱼IgM结构多样性的功能解释和调控机制

To date, two classical immunological paradigms have been operated to govern the development and functionality of the antibody response: 1) affinity maturation is primarily dependent upon antigen-driven selection of both the germline and somatically amended high affinity repertoires, and 2) antibody effector function is isotypically determined. Our recent findings, utilizing the teleost IgM model, suggest that these classical paradigms should be broadened to incorporate the ability of the immune system to transducer the strength of antigen recognition (affinity) into isomerism structural modification that, in turn, modulate the half-life of antibody in serum. More importantly, the discovery of teleost unique feature reveals a heretofore unknown level of sophistication by which the immune system can interpret and response to the antigenic universe. Based on this information, we believe that it is important to explore the functional explanation and cellular regulation of the affinity-induced teleost IgM isomerism. To achieve this goal, utilizing Nile tilapia model, three specific aims are defined: 1) we will perform affinity-dependent antibody isolation to elucidate the difference of the immune functions on IgM isomerism; 2) secondly, we will perform N-glycan analysis to determine the degree of glycoylation of IgM H chain C-terminal; 3) finally we will perform in vitro B cell culture to examine the regulation mechanisms of mannosylation on IgM H chain C-terminal. Upon resolving the mechanisms of affinity-induced teleost IgM isomerism, more cogent vaccine designs could be effectively developed and more precise system to evaluate the protective efficiency of vaccines will be established.

至今，经典免疫学理论有两个基本模式阐述抗体免疫反应的发展和功能：1）亲和力成熟是依赖于机体本身的和通过突变形成的高亲和力抗体的抗原驱动选择过程，和2）抗体的生物效应功能是由抗体的类型所决定的。我们最近研究发现硬骨鱼的免疫系统通过调控结合抗原的亲和力大小来改变分泌的IgM抗体同质异构体结构的比例，从而影响其抗体在血清中的半衰期。这种独特性质的发现是对经典免疫学理论的补充和扩展。本项目以尼罗罗非鱼为硬骨鱼模型，采取细胞体外培养和IgM抗体分离纯化相结合的手段，比较高亲和力和低亲和力IgM免疫功能的差异，分析B细胞受体结合抗原亲和力的大小对其分泌的IgM重链C末端上糖基化的影响，并阐明甘露糖代谢控制因子对IgM重链C末端上甘露糖糖基化的调控机制。率先从细胞和蛋白水平上探究亲和力相关联的硬骨鱼IgM同质异构体的功能差异和调控机制，为高效的渔用疫苗开发和疫苗效果精确评价奠定理论基础。

至今，经典免疫学理论有两个基本模式阐述抗体免疫反应的发展和功能：1）亲和力成熟是依赖于机体本身的和通过突变形成的高亲和力抗体的抗原驱动选择过程，和2）抗体的生物效应功能是由抗体的类型所决定的。我们最近研究发现硬骨鱼的免疫系统通过调控结合抗原的亲和力大小来改变分泌的IgM抗体同质异构体结构的比例，从而影响其抗体在血清中的半衰期。这种独特性质的发现是对经典免疫学理论的补充和扩展。本项目我们以尼罗罗非鱼为硬骨鱼模型，制备了抗尼罗罗非鱼IgM的单克隆抗体，采取细胞体外培养和IgM抗体分离纯化相结合的手段，比较高亲和力和低亲和力IgM免疫功能的差异，克隆表达了与IgM相结合的补体C1和MBL分子并探讨这两个分子与IgM的同质异构体之间免疫功能的差异，并分析了抗体亲和力的大小对其IgM重链C末端上糖基化水平的影响。我们率先从细胞和蛋白水平上探究亲和力相关联的罗非鱼IgM同质异构体的免疫功能差异和形成机制，为高效的渔用疫苗开发和疫苗效果精确评价奠定理论基础。