中文摘要：

目的探讨大鼠肠道树突细胞（DC）介导肥大细胞活化对肠易激综合征（IBS）形成的作用机制。方法20只SD大鼠按数字表随机分成对照组及模型组（各10只），模型组以结直肠扩张联合束缚应激建立大鼠内脏高敏感模型，以腹部收缩反射（AWR）实验评估大鼠内脏敏感性，免疫组织化学方法检测回盲部结肠组织表面分子CD103表达，甲苯胺蓝染色法计数回盲部结肠黏膜肥大细胞，酶联免疫吸附试验（ELISA）法检测肠黏膜白细胞介素（IL）4，IL-9表达，蛋白质印迹法检测肠道蛋白酶激活受体2（PAR-2）表达，磁珠分选技术分离肠系膜淋巴结（MLN）DC和脾脏CD4＋／CD8＋T淋巴细胞，并予以体外共培养，检测DC促淋巴细胞分泌细胞因子的能力。组间比较采用t检验或方差分析。结果模型组大鼠回盲部黏膜肥大细胞数量多于对照组（2．73±0．21比1．13±0．10，P=0．000），PAR-2及IL-4、IL-9的表达均高于对照组[2．13±0．81比0．42±0．29、（7．2±1．2）比（3．3±1．0）pg／ml、（7．3±1．3）比（5．2±0．6）pg／ml，P=0．026、0．000、0．001]，回盲部DC也多于对照组（8．91±2．88比6．34±0．94，P=0．045），体外MLNDC与CD4＋T细胞共培养上清中IL4水平高于对照组[（1．22±0．33）比（0．80±0．48）pg／ml，P=0．000]。结论IBS大鼠肠道DC数目增多，其能通过激活T淋巴细胞产生细胞因子IL4，使肥大细胞处于高敏状态甚至脱颗粒，从而导致IBS内脏高敏感的产生。

英文摘要：

Objective To explore the role of altered characteristics of intestinal dendritic cell（DC） in the induction of visceral hyperalgesia through the activation of mast cells in a rat model of irritable bowel syndrome （IBS）. Methods A total of 20 Sprague-Dawley rats were divided into modeling and control groups （n = 10 each）. The IBS rat model was established by combining colorectal distention with restraint stress. Abdominal withdrawal reflex （AWR） was employed to evaluate visceral sensitivity. The surface marker of intestinal DC was analyzed by immunohistochemistry. Toluidine blue staining was used to determine the number of mast cells （MC）. The expressions of interleukin （IL） 4 and IL-9 in colonic mucosa were measured by enzyme-linked immunosorbent assay （ELISA） and the level of proteinase-activated receptor-2 （PAR-2） was measured by Western blot. Mesenteric lymph node （MLN） DC and splenic CD4＋/ CD8 ＋ T cells were isolated and purified by magnetic label-based technique. Cytokine production of MLN DC co-culturing with CD4 ＋ or CD8 ＋ T cells was determined. Results The number of colonic MC in modeling group was more than that in control group （ （2. 73 ±0. 21 ） vs （ 1.13 ±0. 10） , P =0. 000）. The expressions of PAR-2, IL-4 and IL-9 in colonic mucosa were all higher than those in control group （2.13 ±0. 81 vs 0.42 ±0. 29, （7.2 ±1.2） vs（3.3 ±1.0）pg/ml, （7.3 ±1.3） vs （5.2 ±0. 6） pg/ml, P =0. 026, 0. 000, 0. 001 ）. Co-cultured MLN DC with CD4 ＋ T cells showed a predominant IL-4 secretion in the modeling group （ （ 1.22 ±0. 33 ） vs （0. 80 ±0. 48 ） pg/ml, P = 0. 000）. Conclusion Increased colonic DC may stimulate CD4 ＋ T cells to secrete a high level of IL4 to cause the degranulation of mast cells and the generation of visceral hypersensitivity in IBS rats.