维生素D_3对急性溃疡性结肠炎大鼠肠黏膜Toll样受体2和髓样分化蛋白2及CD14表达的影响

Effect of vitamin D_3 on the expressions of Toll-like receptor 2,myeloid differentiation protein 2 and CD14 in intestinal mucosa of rats with acute ulcerative colitis

目的探讨维生素D_3对溃疡性结肠炎(ulcerative colitis,UC)大鼠肠黏膜Toll样受体2(Toll-like receptor 2,TLR2)和髓样分化蛋白2(myeloid differentiation protein 2,MD2)及CD14表达的影响,及辅助治疗UC的可能机制。方法 30只SD大鼠随机分为正常对照组、模型组和维生素D_3干预组各10只。模型组和维生素D_3干预组将质量分数5%2,4,6-三硝基苯磺酸与体积分数50%乙醇等体积混合后以0.4mL/100g剂量缓慢注入大鼠肠道制备UC模型,正常对照组以等量生理盐水灌肠。维生素D_3干预组在造模成功后第10天起给予胆维丁乳原液1 875u灌胃,模型组和正常对照组给予等剂量生理盐水灌胃,均1次/d,连续10d;比较3组大鼠一般情况及维生素D_3干预第10天疾病活动指数(disease activity index,DAI)评分;维生素D_3干预第10天处死大鼠,取结肠黏膜进行组织病理学评分(histopathological score,HPS),采用免疫组织化学法检测3组结肠黏膜组织TLR2、MD2和CD14的表达情况。结果维生素D_3干预第10天,模型组与维生素D_3干预组DAI[(8.07±1.87)、(5.15±2.40)分]、HPS评分[(14.33±0.97)、(10.01±2.23)分]高于正常对照组(0、0分)(P<0.05),维生素D_3干预组低于模型组(P<0.05);TLR2、MD2和CD14均在肠黏膜上皮细胞细胞质、细胞核中着色;结肠黏膜组织TLR2、MD2和CD14阳性表达率在模型组(90%、80%、100%),维生素D_3干预组(80%、50%、50%)均高于正常对照组(0、0、0),且模型组高于维生素D_3干预组(P<0.05)。结论结肠黏膜组织中TLR2、MD2和CD14高表达可能与UC发病有关,维生素D_3可通过抑制TLR2、MD2和CD14表达减轻UC大鼠的肠道炎症反应,发挥辅助治疗UC的作用。

Objective To explore the effects of vitamin D_3(VD_3)on the expressions of Toll-like receptor 2(TLR2),myeloid differentiation protein 2(MD2)and CD14 in the intestinal mucosa of rats with acute ulcerative colitis(UC)and its possible mechanism in the adjuvant therapy of UC.Methods Thirty SD rats were randomly divided into normal control group,model group and VD_3 group,with 10 rats in each group.Model group and VD_3 group were injected with the mixture of 2,4,6-trinitro-benzene sulfonic acid and equivalent volume of ethanol into intestinal tract with0.4mL/100 g to establish UC models,and normal control group was injected with equivalent volume of normal saline.VD_3 group received gavage with 1 875 uof VD_3by day 10 after modeling,once a day,totally for 10 d,and model group and normal control group received gavage with the equivalent volume of normal saline.The general data and disease activity index scores by day 10 after gavage were compared among three groups.All rats were sacrificed by day 10 after gavage to obtain intestinal mucosa.The histopathology score was detected,and the expressions of TLR2,MD2 and CD14 were measured by immunohistochemistry in three groups.Results The disease activity index score and histopathology score were significantly higher in model group(8.07±1.87,14.33±0.97)and VD_3 group(5.15±2.40,10.01±2.23)than those in normal control group(0,0)(P<0.05),and were significantly lower in VD_3 group than those in model group(P<0.05).TLR2,MD2 and CD14were pigmented in the cytoplasm and nucleus of intestinal epithelial cell.The positive rates of TLR2,MD2 and CD14 were significantly higher in model group(90%,80%,100%)and VD_3 group(80%,50%,50%)than those in normal control group(0,0,0),and higher in model group than those in VD_3group(P<0.05).Conclusion The high expressions of TLR2,MD2 and CD14are involved in UC.VD_3 could alleviate intestinal inflammation in the adjuvant therapy of UC by inhibiting the expressions of TLR2,MD2 and CD14.