大黄酸对DSS诱导溃疡性结肠炎小鼠的治疗作用及机制探讨

Effect and Mechanism of Rhein on DSS-induced Ulcerative Colitis in Mice

目的:探讨大黄酸对葡聚糖硫酸钠(DSS)诱导的小鼠溃疡性结肠炎的治疗作用及其相关的作用机制。方法:C57BL/6雄性小鼠,随机分为6组,分别为正常组,模型组,美沙拉秦组(0.8 g·kg^(-1))与大黄酸低、中、高剂量组(6.25,12.5,25 mg·kg^(-1)),每组10只。除正常组给予蒸馏水外,其余各组均采用3%DSS溶液自由饮用7 d诱导溃疡性结肠炎模型。造模第1天开始灌胃给药,正常组与模型组给予等量的蒸馏水,连续给药14 d。每天观察小鼠体重、粪便性状、隐血便血情况,评分并计算疾病活动指数(DAI);取结肠,测量长度,制作结肠石蜡切片,苏木素-伊红(HE)染色后显微镜下观察其病理变化;取外周血,收集血清,酶联免疫吸附测定(ELISA)试剂盒检测小鼠血清中鞭毛蛋白抗体含量;蛋白质免疫印迹(Western blot)检测小鼠结肠组织Toll样受体5(TLR5),核因子-κB p65(NF-κB p65)蛋白的表达水平。结果:与正常组比较,模型组小鼠DAI分显著升高(P<0.01);结肠明显缩短(P<0.01);黏膜上皮、肠腺等结构消失,黏膜下层大量淋巴细胞浸润,血管扩张。给予美沙拉秦与各剂量的大黄酸后,上述症状均得到缓解(P<0.05,P<0.01)。与正常组比较,模型组血清中鞭毛蛋白抗体含量升高(P<0.01);结肠组织TLR5,NF-κBp65蛋白表达明显增加(P<0.01),美沙拉秦组与各剂量大黄酸组均减少(P<0.05,P<0.01)。结论:大黄酸具有治疗DSS诱导的小鼠溃疡性结肠炎的作用,其机制可能与影响TLR5/NF-κB信号通路有关。

Objective： To investigate the efficacy and its mechanism of rhein on dextran sulphate sodium （DSS）-induced ulcerative colitis in mice. Method： C57BL/6 male mice were randomly divided into 6 groups： normal control group, model group, mesalazine treatment group, low-dose rhein group, middle-dose rhein group and the high-dose rhein group （6.25, 12.5, 25 mg·kg-1） , n = 10 in each group. The mice in normal control group received distilled water, while all the other mice were treated with 3% dextra sulfate sodium for 7 days to induce the ulcerative colitis model. From the first day of modeling, mesalazine and different concentrations of rhein were given by gavage for 14 days continuously, and equal volume of distilled water was given in normal group and model group. The body weight, defecation condition and hematochezia of the mice were observed and recorded everyday; scores of disease activity index （DAI） were calculated and evaluated; colon was taken and its length was measured; colon paraffin slices were prepared and their pathological changes were observed under microscope after HE staining. Peripheral blood was taken and the serum was collected to detect the level of anti-flagellin antibody by using ELISA kit. The expression levels of Toll like receptor 5 （TLRS） and nuclear factor （NF）-KB p65 in colon were measured by Western blot. Result： As compared with the normal control group, DAI scores were significantly increased in model group （P 〈 0.01 ） ; the colon length was significantly shortened （P 〈 0.01 ） ; meanwhile, epithelium and intestinal gland disappeared, with a large number of lymphocyte infiltration and local vascular dilation in submucous layer. Above symptoms were ameliorated after giving mesalazine and different concentrations of rhein （P 〈0.05, P 〈 0.01 ）. The anti-flagellin antibody in serum, the expression levels of TLR5 and NF-κB p65 were significantly increased in model group （P 〈 0.01 ） as compared with the normal group ; while these levels were decreased after treatment by mesalazine and different concentrations of rhein （P 〈 0.05, P 〈 0.01 ）. Conclusion： Rhein could treat DSS-induced ulcerative colitis in mice, and its mechanism may be related to inhibiting the expression of TLRS/NF-κB p65 pathway.