Toll样受体4单克隆抗体干预小鼠实验性溃疡性结肠炎对信号转导通路的影响

Therapeutic effect of Toll like receptor 4 monoclonal antibodies in a mouse model of experimental ulcerative colitis

目的探讨Toll样受体4单克隆抗体（Toll like receptor 4 monoclonal antibodies，TLR4mAb）干预葡聚糖硫酸钠（DSS）诱导溃疡性结肠炎（UC）小鼠肠黏膜中TLR4-P38丝裂原活化蛋白激酶（MAPK）-c—fos／c—jun信号转导通路的影响情况。方法30只BALB／c小鼠分为对照组、模型组以及低、中、高剂量干预组。对照组小鼠饮用蒸馏水7d；其他四组小鼠饮用5％DSS溶液7d建立急性期UC模型。造模同时，干预组小鼠分别以低（2pg）、中（10pg）、高剂量（20pg）TLR4mAb腹腔注射，共4次，7d后处死小鼠，观察疾病活动指数（DAI）、结肠组织病理学评分（HPS）。RT-PCR法检测各组肠黏膜TLR4的mRNA表达，Western印迹法测定各组肠黏膜P38MAPK、磷酸化P38MAPK、c—fos、c—jun的蛋白表达。结果模型组TLR4mRNA表达明显高于对照组（P〈0．01）。与模型组相比，低、中、高剂量干预组DAI指标和HPS指标均有不同程度缓解。P38MAPK及c-jun蛋白表达在低、中、高剂量干预组呈逐步递减，且均较模型组有明显下降（P〈0．01）。与模型组相比，低、中、高剂量干预组小鼠肠黏膜磷酸化P38MAPK蛋白及c-fos蛋白表达差异均无统计学意义（P〉0．05）。结论早期应用TLR4mAb对DSS诱导小鼠急性期UC有干预作用，其作用机制可能与抑制TLR4--P38MAPK—c-jun信息转导通路有关。

Objective To evaluate the therapeutic effects of Toll like receptor 4 monoclonal antihodies（TLR4mAh） in a mouse model oi dextran sulfate sodium（DSS）-induced ulcerative colitis（UC） and the modulation of TLR4--P38MAPK--c-fos/c-jun signaling pathway. Methods Male BALB/C mice were received 5% （w/v） of DSS in drinking water for 7 days to induce acute intestinal inflammation. The mice in control group were given distilled water freely, some of DSS treated mice were also received 2 μg, 10 μg or 20μg of TLR4mAh intraperitonealy at the hegining of DSS treatment. At the end of 7 day period, the mice were sacrificed to harvest tissue. Disease activity index（DAI） and histopathological scor.e（HPs） were evaluated. The mRNA expression of TLR4 was measured by RT-PCR. The protein expressions of P38MAPK, phosphorylated-P38MAPK, c-fos as well as c-jun were examined by Western blot. Results TLR4 mRNA expression was significantly increased in DSS treated mice compared to the controls （P 〈 0.01）. The DAI and HPS in all three interventional groups were reduced in a dose-dependent manner. The level of P38MAPK and c-jun was also decreased tendency in a dose dependant mamner, and had statistical significance compared with untreated mice （P 〈 0.01）. There was no statistical difference in levels of phosphorylated-P38MAPK and c-fos between TLK4mAh treated and untreated mice （P〉0.05）. Conclusions TLR4mAh pretreatment can attenuate or even block the initiation and progression of DSS-induced acute UC. Blocking the TLR4--P38MAPK--c-jun signaling pathway with TLR4mAh might he a novel therapeutic approach of UC treatment.