免疫原性HER2突变体蛋白对小鼠T细胞亚群分化的影响

Effects of immunogenic HER2 on the differentiation of T-cell in mouse

为了考察蛋白质中定点引入对硝基苯丙氨酸后对T细胞分化的影响,以人表皮生长因子受体2(HER2)胞外区为模型分子,利用实验室前期构建的工程菌表达了定点引入对硝基苯丙氨酸的HER2突变体。用含对硝基苯丙氨酸的HER2突变体免疫小鼠,分析其对小鼠T细胞亚群分化的影响。研究结果显示,对硝基苯丙氨酸的引入显著增强了HER2的免疫原性,免疫5周后,突变体免疫组的小鼠体内抗HER2抗体滴度明显高于PBS组和原型免疫组的小鼠;流式细胞术检测结果显示,小鼠淋巴结内Tfh细胞比例从4%上升至8%,而Treg细胞比例从5%下降至1%;QT-PCR分析结果显示,Tfh细胞关键转录因子Bcl-6的mRNA水平提高了2倍,而Treg细胞关键转录因子FOXP3的mRNA水平明显降低;ELISA法检测血清中Tfh细胞效应因子IL-21的含量从4 pg/m L上升至28 pg/m L。上述研究结果证实,含有对硝基苯丙氨酸的HER2突变体可以通过激活Tfh细胞分化而引起高效免疫应答。

In order to investigate the effects of p-nitrophenylalanine on the differentiation of T lymphocyte,human epidermal growth factor receptor2(HER2)mutants were constructed by incorporating p-nitrophenylalanine to the extracellular domain of HER2.Mice were immunized with HER2mutant to analyze the effects of p-nitrophenylalanine on the differentiation of T cell subsets.The results showed that the immunogenicity of HER2protein was significantly enhanced by incorporation of immunogenic amino acids.HER2mutants induced production of more anti-WT-HER2antibody and greater titer of antibody than PBS and wild-type HER2in the fifth week.The differentiation frequency of Th1and Th2cells showed no significant difference,but the differentiation frequency of Tfh cell was found to increase from4%to8%,while the differentiation frequency of Treg cell was found to decrease from5%to1%through flowcytometry analysis.The gene expression of Bcl-6and FOXP3were determined by quantitative real-time PCR.The results showed that the expression of Bcl-6mRNA increased about2fold,while the expression of FOXP3mRNA could be decreased to about50%in HER2mutant-immunized group.The secretion level of IL-21in serum was also detected to increase from4to28pg/mL in HER2mutant-immunized group.The above results confirm that HER2mutants containing p-nitrophenylalanine can cause an efficient immune response by activating Tfh cell differentiation.