腹泻型肠易激综合征大鼠肠道树突细胞对Th1/Th2免疫平衡以及内脏高敏感的影响

Effects of Intestinal Dendritic Cells on Th1/Th2 Immune Balance and Visceral Hypersensitivity in Irritable Bowel Syndrome With Diarrhea Rats

背景:肠易激综合征(IBS)的发病原因和机制尚未完全明确,临床上缺乏有效的预防和诊治手段。近年越来越多的研究认为肠道局部黏膜免疫功能异常在IBS发病中起有重要作用。目的:探讨肠道树突细胞(DC)在腹泻型IBS(IBS-D)大鼠结肠黏膜Th1/Th2免疫应答途径失衡中的作用及其对内脏高敏感的影响。方法:将45只成年SD大鼠随机分为空白对照组、NS对照组和模型组,每组各15只。以乙酸灌肠联合束缚应激制备大鼠内脏高敏感模型,以腹壁回撤反射(AWR)实验和大鼠粪便性状评估内脏敏感性。采用流式细胞分选技术分离经相应特异性抗体标记的肠系膜淋巴结DC以及脾脏初始CD4+T细胞并体外进行共培养,以MTT法检测CD4+T细胞的增殖能力,ELISA法检测Th1途径细胞因子IL-12、IFN-γ和Th2途径细胞因子IL-4、IL-9的分泌能力。结果:与NS对照组和空白对照组相比,模型组大鼠内脏敏感性明显增高(P<0.05),肠道淋巴结来源的DC促进脾脏CD4+T细胞增殖的能力增强(P<0.05),IL-4和IL-9分泌量明显升高(P<0.05),IL-12分泌量明显减少(P<0.05)。结论:IBS-D内脏高敏感大鼠肠道DC的抗原呈递能力增强,诱导Th2途径免疫应答能力亢进,进而导致局部肠道黏膜Th1/Th2免疫应答途径失衡。

Background:The etiology and pathogenesis of irritable bowel syndrome(IBS)are not yet clear,and is lack of effective means for its prevention,diagnosis and treatment in clinic.In recent years,more and more studies showed that intestinal local mucosal immune dysfunction plays an important role in the pathogenesis of IBS.Aims:To investigate the role of intestinal dendritic cells(DC)in the imbalance of colonic mucosal Th1/Th2 immune response pathway in IBS with diarrhea(IBS-D)rats and its effect on visceral hypersensitivity.Methods:Forty-five adult SD rats were randomly divided into blank control group,NS control group and model group,and each group consisted of 15 rats.Visceral hypersensitive model was established by acetic acid enema combined with restraint stress.Abdominal withdrawal reflex(AWR)test and fecal characteristics were used to evaluate the visceral sensitivity.Flow cytometry separation technique was used to isolate DC from mesenteric lymph nodes and CD4+T cells from spleen,and the DC were co-cultured with CD4+T cells in vitro.MTT assay was used to detect the proliferation of CD4+T cells.The levels of Th1 pathway cytokines IL-12,IFN-γand Th2 pathway cytokines IL-4,IL-9 were determined by ELISA.Results:Compared with NS control group and blank control group,visceral sensitivity was significantly increased(P<0.05),DC from intestinal lymph nodes significantly enhanced the proliferation of spleen CD4+T cells,and levels of IL-4 and IL-9 were significantly increased(P<0.05),while level of IL-12 was significantly reduced in model group(P<0.05).Conclusions:The antigen presenting ability of DC is enhanced in IBS-D rats,which induces the hyperactivity of immune response of Th2 pathway,leading to Th1/Th2 immune response imbalance of local intestinal mucosa.