CD11b在小鼠急性结肠炎模型中的表达及鼠李糖乳杆菌的调节作用

The expression of CD11b in acute colitis model of mouse and regulatory effect of Lactobacillus rhamnosus GG

目的研究CD11b在炎症性肠病模型小鼠结肠组织中的表达及定位,探讨鼠李糖乳杆菌(LGG)对CD11b的调节作用。方法将28只SPF级小鼠随机分为3组:Ctrl组8只、DSS组10只、DSS+LGG组10只,给予3%DSS自由饮用建立急性结肠炎模型,DSS+LGG组小鼠提前1周管饲LGG共14 d;模型建立期间观察小鼠一般状态变化、粪便性状改变并记录每日体质量;于DSS饮用第8天处死小鼠留取腹主动脉血液及结肠标本,检测外周血荧光素异硫氰酸酯-葡聚糖(FITC-dextran)浓度以评估肠道通透性,光镜下观察结肠病理变化,并通过免疫组化染色及Western Blot明确CD11b表达情况。结果 DSS组小鼠较Ctrl组体质量下降及便血情况明显,疾病活动指数(DAI)明显升高;DSS+LGG组小鼠症状缓解,与DSS组相比体质量下降不明显(t=3.894,P=0.001 3),DAI评分明显下降(t=2.390,P=0.029 5),外周血FITC-dextran浓度下降(t=2.406,P=0.028 6),光镜下结肠组织病理评分明显下降(t=3.450,P=0.003 3);应用免疫组化染色发现CD11b在正常结肠组织中几乎不表达,DSS模型中表达在黏膜下中性粒细胞聚集处,受损的黏膜表层也有少量表达;DSS+LGG组阳性表达细胞较少;应用Western Blot半定量检测发现LGG干预后CD11b表达减少(t=3.039,P=0.012 5)。结论 CD11b在急性结肠炎小鼠结肠组织中表达明显增加,LGG干预可降低小鼠疾病活动度,改善肠通透性,抑制结肠组织CD11b的表达,说明LGG可能通过抑制中性粒细胞产生趋化因子来发挥炎症抑制作用。

Objective To study the expression and localization of CD11 b in the colon of mice with inflammatory bowel disease, and explore the regulatory effect of Lactobacillus rhamnosus GG(LGG) on CD11 b. Methods A total of 28 mice were randomly divided into three groups: Ctrl group(n=8), DSS group(n=10) and DSS+LGG group(n=10). The model of acute colitis was established by giving free drinking of 3% DSS. The intervention group was fed with LGG 1 week before drinking DSS for 14 days. During the establishment of the model, the general state and stool characteristics of the mice were observed, and the body weight was recorded daily. On the 8 th day, the mice were killed to collect blood and colon samples. The concentration of FITC-dextran in peripheral blood was tested to evaluate intestinal permeability. The pathological changes of colon were observed under light microscope, and the expression of CD11 b was observed with immunohistochemical staining and Western Blot. Results The change of body weight, hematochezia and disease activity index(DAI) of mice in the DSS group were significantly severer than those in the Ctrl group. The symptoms were relieved and the weight loss wasn′t obvious in the DSS+LGG group(t=3.894, P=0.001 3), peripheral blood FITC-dextran concentration decreased(t=2.406, P=0.028 6), DAI decreased significantly(t=2.390, P=0.029 5), and the histological score of colon tissue under light microscope decreased significantly(t=3.450, P=0.003 3). Immunohistochemical staining showed that there was hardly expression of CD11 b in normal colonic tissue, but in submucosal neutrophil aggregation and damaged mucosal surface in DSS model, while there were fewer positive expressing cells in DSS+LGG group. Semi-quantitative analysis with Western Blot showed that the expression of CD11 b decreased after the intervention of LGG(t=3.039, P=0.012 5). Conclusion The expression of CD11 b in colonic tissue of mice with acute colitis significantly increased. The intervention of LGG can reduce the disease activity, improve intestinal permeability and inhibit the expression of CD11 b in colon tissue, indicating that LGG may play an anti-inflammatory role by inhibiting the production of neutrophil chemokine.