感染后肠易激综合征模型小鼠肠道组织中Th1／Th2的漂移

Th1/Th2 shift in gut of mouse model of postinfectious irritable bowel syndrome

目的观察感染后肠易激综合征（PIIBS）模型小鼠肠道组织中Th1细胞因子白细胞介素（IL）－12和Th2细胞因子IL-4表达的变化。方法30只成年雄性NIH小鼠，分为对照组（8只）和模型组（22只）。模型组予以旋毛虫幼虫囊胞感染，每周测量小鼠体重，于感染后8周通过腹壁回撤反应（AWR）评分评估小鼠对结直肠扩张的内脏敏感性。感染后8周处死所有小鼠，取空肠、末端回肠、近端结肠和远端结肠行病理切片，HE染色观察肠道炎症情况。应用RTPCR和Western印迹法检测肠道各部位组织中IL-12和IL-4的mRNA和蛋白表达量。结果模型组感染后2周体重增长率为-1．08％±1．08％，明显低于正常组（3．09％±1．35%，P〈0．05），感染后8周体重变化与对照组差异无统计学意义（P〉0．05）。模型组感染后2周肠道炎症明显，感染后8周肠道无明显炎症表现。在结直肠扩张压力为30、45和60mmHg（1mmHg=0．133kPa）时，模型组AWR评分均高于正常组（P〈0．05）；模型组疼痛阀值低于正常对照组（P〈0．05）。模型组小鼠末端回肠和近端结肠组织中IL-12mRNA及蛋白表达量均高于对照组（P％0．05）；IL-4mRNA及蛋白在各肠段中的表达均低于对照组（P〈0．05）。结论PI—IBS小鼠肠道组织中存在Th1／Th2平衡漂移，为PI—IBS的治疗提供新的思路。

Objective To observe the expressions of Th1 cytokin Einterleukin （IL- 12 ] and Th2 cytokin （IL-4） in gut of the mouse model of postinfeetious irritable bowel syndrome （PI IBS）. Methods Thirty mice were divided into control group （n 8） and model group （n=22,infected with Trichinella spiralis）. The weight of the mouse was measured weekly after infection. Visceral sensitivity of colorectal distention in mouse was accessed by abdominal withdrawal reflex （AWR） at 0 and 8 weeks after infection. All mice were sacrificed at the 8th week, and tissues of jejunum, terminal ileum, proximal colon and distal colon were observed for inflammation with HE staining. The mRNA and protein expressions of IL -12 and IL-4 were examined by RT-PCR and Western blotting, respectively. Results Two weeks after infection, body weight was decreased in model group compared with control group （--1.08%±1.08 % vs 3.09%±1.35%,P〈 0.05）, but there was no significant difference at the 8th week between two groups （P〉0.05）. Severe inflammation was observed in the gut of mouse 2 weeks after infection, however it was recovered at the 8th week. The score of AWR was higher in model group at 30,45 and 60 mmHg in comparison with control group （P〈0. 05）, whereas the perceptual threshold was lower in model group than in the control group （P0.05）. In comp^rison with control group, increased expressions of IL- 12 mRNA and protein in ileocecum and proximal colon as well as decreased expressions of IL-4 mRNA and protein in all parts of gut were found in model group （P〈0. 05）. Conclusion Th1/Th2 shift may involve in gut of PI-IBS mouse. which provides a new idea for treatment of PI-IBS.