Dock2通过调节T细胞活性和抗原特异性IgG抗体的产生来控制肠道柠檬酸杆菌感染

Dock2 controls enteric bacterial clearance through regulating T cell activity and antigen-specific IgG production

目的探讨Dock2在宿主对抗柠檬酸杆菌感染的适应性免疫中的功能,研究柠檬酸杆菌感染后期淋巴细胞变化与细菌清除率之间的关系。方法取WT及Dock2-/-小鼠灌胃感染柠檬酸杆菌,观察21 d内感染情况,ELISA检测21 d小鼠血清中IFN-γ、TNF-α、KC、MCP-1、MIP-2、IL-6和IL-17的蛋白表达水平及特异抗体IgM、IgG、IgG1、IgG2b、IgG2c和IgG3的水平;流式细胞术检测淋巴T细胞及胸腺细胞情况。分离WT和Dock2-/-的T淋巴细胞通过尾静脉注射到TCRa-/-小鼠体内,ELISA检测IgG、IgG1、IgG2b、IgG2c、IgG3、IgA和IgM的水平。取感染D0和D21的WT小鼠血清注射到感染柠檬酸杆菌的Dock2-/-小鼠尾静脉中后,记录存活率。结果感染后,Dock2-/-小鼠具有更高水平的促炎细胞因子和更多的髓样细胞浸润。但是,Dock2-/-小鼠激活的T细胞、B细胞数量减少且血清抗原特异性IgG抗体产生降低。T细胞转移和血清转移对柠檬酸杆菌诱导的结肠炎具有抑制作用。结论Dock2对于柠檬酸杆菌感染后期宿主清除致病菌至关重要。

Objective To explore the function of Dock2 in the host’s adaptive immunity against C.rodentium infection,and study the relationship between the changes of lymphocytes and bacterial clearance in the late stage of C.rodentium infection.Methods WT and Dock2-/-mice were intragastrically infected with C.rodentium to observe the infection within 21 days.ELISA was used to detected IFN-γ,TNF-α,KC,MCP-1 and MIP-2 in the sera of mice during 21 days,the protein expression levels of IL-6 and IL-17,and the levels of specific antibodies IgM,IgG,IgG1,IgG2b,IgG2c and IgG3;flow cytometry was used to detect T lymphocytes and thymocytes.The T lymphocytes isolated from WT and Dock2-/-were injected into the TCRa-/-mice by tail veins,and the levels of IgG,IgG1,IgG2b,IgG2c,IgG3,IgA and IgM were detected by ELISA.Sera of WT mice at DO and D21 after infection were injected into the tail veins of Dock2-/-mice followed by infection,and the survival rates were recorded.Results:After C.rodentium infection,Dock2-/-mice had much more production of pro-inflammatory cytokines and macrophage/neutrophil infiltration than WT mice.The mechanism of bacterial clearance disorder caused by Dock2 deletion after C.rodentium infection may be associated with the T-cell and B-cell deficiency,and reduced serum antigen-specific IgG antibody in Dock2-/-mice.Consistently,T cell transfer and serum transfer has inhibitory effects on C.rodentium-induced colitis.Conclusion Dock2 was required for host bacterial clearance after C.rodentium infection.