实验性结肠炎大鼠树突状细胞表型和功能变化以及益生菌的作用

Modulation of Dendritic Cell Phenotype and its Function by Probiotics in Experimental Colitis in Rats

背景:在炎症性肠病(IBD)发病机制中,肠道菌群紊乱是重要因素之一,益生菌对其有治疗作用,但其免疫调节机制尚不清楚。目的:观察双歧三联活菌对实验性结肠炎大鼠肠道炎症、肠道菌群的调节和树突状细胞(DCs)的活化及其功能的影响。方法:30只雄性Wistar大鼠随机分为正常对照组、模型对照组和双歧三联活菌治疗组,每组10只,行大鼠结肠组织炎症评分和肠道菌群分析;流式细胞仪检测DCs表面主要组织相容性复合物(MHC)-Ⅱ和共刺激分子CD86的表达;混合淋巴细胞反应(MLR)法检测DCs刺激淋巴细胞增殖的能力。结果:正常对照组、模型对照组和双歧三联活菌治疗组结肠组织炎症评分分别为4.35±0.88、10.25±1.36和7.94±0.85,各组间均有显著差异(P<0.05)。模型对照组较正常对照组粪便中乳酸杆菌和双歧杆菌减少(P<0.01),肠杆菌和真菌增加(P<0.01)。双歧三联活菌治疗组肠道菌群紊乱得到部分纠正,乳酸杆菌和双歧杆菌较模型对照组明显增加,接近正常对照组。正常对照组、模型对照组和双歧三联活菌治疗组肠系膜淋巴结DCs中MHC-Ⅱ表达率分别为(26.2±7.2)%、(84.6±9.4)%和(66.5±8.4)%(P<0.05);CD86分别为(20.5±7.7)%、(80.6±8.8)%和(59.8±10.0)%,各组间均有差异(P<0.05)。结论:益生菌治疗能部分改善结肠炎大鼠的肠道菌群紊乱,使肠系膜淋巴结中活化的DCs明显下调,降低其刺激T细胞增殖的能力,从而可能降低肠道炎症反应。

Distortion of intestinal flora is one of the major mechanisms involved in the development of inflammatory bowel disease （IBD）, probiotics have therapeutic effect on IBD, yet its immune response modulating mechanism is not well known. Aims： To assess the effect of probiotics on intestinal tract inflammation, modulation of intestinal microbial flora and activation and function of dendritic cells （DCs）. Methods： Thirty Wistar rats were randomly divided into normal control group, colitis control group and probiotics-treated group. Histological inflammatory score of colonic mucosa was studied and intestinal microbial flora was analyzed. Expressions of major histocompatibility complex （MHC）-Ⅱ and costimulatory molecule CD86 on DCs were analyzed by flow cytometry. The capacity of DCs to stimulate T cell proliferation was determined by mixed lymphocyte reaction （MLR）. Results： The colonic mucosal inflammatory score differed significantly between normal control group, colitis control group and probiotics-treated group （4.35±0.88, 10.25±1.36 and 7.94±0.85, respectively, P〈0.05）. The amount of lactobacillus and Bacillus bifidus in feces was lower in colitis control group than that in normal control group, while the amount of enterobacillus and fungus was higher （P〈0.01）. The microbial flora imbalance in cecum was ameliorated in probiotics-treated group and the amount of lactobacillus and Bacillus bifidus was significantly higher than that of colitis control group and close to that of normal control group. Expressions of MHC-Ⅱ molecule on DCs in normal control group, colitis control group and probiotics-treated group were （26.2±7.2）%, （84.6±9.4）% and （66.5±8.4）%, respectively （P〈0.05）, while that of CD86 were （20.5±7.7）%, （80.6±8.8）% and （59.8±10.0）%, respectively （P〈0.05）. Conclusions： Probiotics may attenuate the distortion of intestinal microbial flora imbalance, significantly down-regulate the activation of DCs in mesenteric lymph nodes, decrease its capacity of stimulating T cell proliferation, thereby decrease the intestinal inflammatory response in rats colitis.