【摘要】 目的:转录因子干扰素调节因子(interferon regulatory factor,IRF)家族与Th17的发育密切相关,近年来发现Th17细胞在炎症性肠病的发病中发挥重要作用,本研究探讨IRF8对Th17发育及T细胞转染免疫介导的小鼠实验性肠炎的影响。方法:(1)采用流式细胞术分选野生型(WT)或IRF8全基因敲除(IRF8-/-)小鼠脾脏和淋巴结的naive CD4+T细胞(CD4+CD62L+CD44low),在Th1、Th2或Th17极化的条件下培养,采用流式细胞术检测Th1、Th2和Th17的比例。(2)建立实验性肠炎模型:采用免疫磁珠法分选WT或IRF8-/-小鼠中的脾脏和淋巴结中CD4+CD25+Treg,WT小鼠的CD4+CD45RBhiT细胞单独或者分别联合WT或IRF8-/-小鼠的CD4+CD25+Treg腹腔注射给RAG1-/-小鼠;WT或IRF8-/-小鼠的naive CD4+CD45RBhiT细胞腹腔注射给RAG1-/-小鼠;观察上述小鼠每周体重的变化,第5周时处死小鼠,进行结肠炎病理评分和肠系膜淋巴结T淋巴细胞亚群检测。结果:(1)IRF8-/-较WT的naive CD4+T细胞在极化条件下向Th17细胞分化更明显(P<0.01),而对Th1和Th2细胞的分化无影响(P>0.05)。(2)CD4+CD45RBhiT细胞转染给RAG1-/-小鼠,IRF8-/-较WT供体鼠引起的RAG1-/-小鼠体重显著降低(P<0.05),结肠炎评分显著增高(P<0.05),且肠系膜淋巴结中IL-17+CD4+细胞比例明显增高(P<0.01),而IFN-γ+CD4+和Foxp3+CD4+细胞比例无影响(P>0.05);IRF8-/-小鼠的CD4+CD25+Treg对WT小鼠CD4+CD45RBhiT细胞转染给RAG1-/-小鼠诱发的免疫介导的结肠炎显示出正常的免疫抑制作用。结论:转录因子IRF8基因敲除促进CD4+T细胞向Th17细胞分化,促进转染naive CD4+T细胞诱导的实验性结肠炎的发生,IRF8基因敲除小鼠Treg细胞免疫抑制功能正常。更多还原

【Abstract】 AIM:To explore the impact of interferon regulatory factor 8(IRF8) on Th17 cell differentiation and naive CD4+T cell immune-mediated mouse experimental colitis.METHODS:Naive CD4+T cells(CD4+CD62L+ CD44low) from the spleens and lymph nodes of wild-type(WT) or IRF8 conventional knockout(IRF8- /-) mice were sorted by flow cytometry.The naive CD4+T cells were cultured under the polarized conditions of Th1 and Th2 and Th17,and then the ratios of Th1,Th2 and Th17 in these cells were detected by flow cytometry.The CD4+CD25+Treg cells were sorted by immunomagnetic beads,and CD4+CD45RBhiT cells from the spleens and lymph nodes of WT or IRF8- /-mice were purified by flow cytometry.To establish the experimental colitis model,the CD4+CD45RBhiT cells from WT mice or IRF8- /-mice were intraperitoneally injected into the RAG1- /-mice.The CD4+CD45RBhiT cells from WT mice were intraperitoneally injected alone,or combined with CD4+CD25+Treg cells from WT mice or IRF8- /-mice into the RAG1-/-mice,respectively.The changes of the body weight in the experimental model mice were measured every week,and the mice were sacrificed at the fifth week for evaluating the colitis pathological score and T lymphocyte subtypes.RESULTS:Under polarized conditions,the ratio of Th17 cells in IRF8- /-group was significantly higher than that in WT group,and no difference of the ratios of Th1 or Th2 cells between these 2 groups was observed.The body weight of RAG1- /-mice decreased significantly,and the colon pathological scores of the RAG1- /-mice injected with CD4+CD45RBhiT cells from the IRF8- /-mice were higher than those of the RAG1- /-mice injected with CD4+CD45RBhiT cells from the WT mice(P <0.05).Meanwhile,the ratio of IL-17+CD4+cells in mesenteric lymph nodes in IRF8- /-group was also higher than that in WT group,but no difference of the ratios of IFN-γ+CD4+cells or Foxp3+CD4+cells between the 2 groups was observed.Moreover,CD4+CD25+Treg cells from the WT mice or the IRF8- /-mice showed equivalent immunosuppression in the course of experimental colitis model,in which CD4+CD45RBhiT cells from the WT mice were injected into the RAG1- /-mice.CONCLUSION:Knockout of transcription factor IRF8 gene promotes the naive CD4+T cells to differentiate into Th17 cells,consequently exacerbates immune-mediated experimental colitis.IRF8- /-Treg cells display normal T effector suppressive activity in the process of immune-mediated experimental colitis.更多还原