Qin Da, Li Ying, Chen Xiaoyan, Li Liyang, Wang Guihua, Hou Xilin, Yu Liyun
College of Life Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, China.
College of Animal Science and Technology, Heilongjiang Bayi Agricultural University, Daqing 163319, China.
Life (Basel). 2023 Sep 20;13(9):1936. doi: 10.3390/life13091936.
Although secretory IgA (SIgA) is the dominant antibody in mucosal secretions, the capacity of the SIgA-antigen complex to prime the activation of dendritic cells (DCs) and T cells in the intestinal epithelium is not well understood. To this end, the SIgA-ETEC F5 immune complexes (ICs) were prepared via Ni-NTA pull-down. After injecting the ICs into the intestines of SPF BALB/c mice, most ICs were observed in the Peyer's patch (PP). We established a microfold (M) cell culture model in vitro for transport experiments and the inhibition test. To evaluate the priming effect of mucosal immunity, we employed the DC2.4 stimulation test, T lymphocyte proliferation assays, and cytokine detection assays. We found that the ICs were taken up via clathrin-dependent endocytosis through M cells. The high expression of costimulatory molecules CD86, CD80, and CD40 indicated that the ICs promoted the differentiation and maturation of DC2.4 cells. The stimulation index (SI) in the complex group was significantly higher than in the control group, suggesting that the ICs stimulated the proliferation of primed T cells. The secretion of some cytokines, namely TNF-α, IFN-γ, IL-2, IL-4, IL-5, and IL-6, in spleen cells from the immunized mice was upregulated. These results indicate that ETEC F5 delivery mediated by SIgA in PPs initiates mucosal immune responses.
尽管分泌型免疫球蛋白A（SIgA）是黏膜分泌物中的主要抗体，但SIgA-抗原复合物启动肠道上皮中树突状细胞（DCs）和T细胞活化的能力尚未完全明确。为此，通过镍-氮三乙酸亲和层析法制备了SIgA-肠毒素大肠杆菌F5免疫复合物（ICs）。将ICs注射到无特定病原体（SPF）BALB/c小鼠肠道后，发现大多数ICs存在于派尔集合淋巴结（PP）中。我们建立了体外微褶（M）细胞培养模型用于转运实验和抑制试验。为评估黏膜免疫的启动效应，我们采用了DC2.4刺激试验、T淋巴细胞增殖测定和细胞因子检测试验。我们发现ICs通过网格蛋白依赖的内吞作用被M细胞摄取。共刺激分子CD86、CD80和CD40的高表达表明ICs促进了DC2.4细胞的分化和成熟。复合物组的刺激指数（SI）显著高于对照组，表明ICs刺激了致敏T细胞的增殖。免疫小鼠脾细胞中一些细胞因子，即肿瘤坏死因子-α（TNF-α）、干扰素-γ（IFN-γ）、白细胞介素-2（IL-2）、白细胞介素-4（IL-4）、白细胞介素-5（IL-5）和白细胞介素-6（IL-6）的分泌上调。这些结果表明，PP中由SIgA介导的肠毒素大肠杆菌F5传递引发了黏膜免疫反应。
