衰老对于实验性小鼠结肠炎的影响及机制

目的 研究衰老对于实验性小鼠结肠炎的影响及其可能机制。方法 雄性C57BL/6小鼠青年(6~8周)和老年(56周)各10只,各分为对照组和实验组(共4组,每组5只),实验组予葡聚糖硫酸钠(DSS)饮用水,对照组予自由饮用水7 d,第8天处死。采用实时荧光定量PCR检测小鼠结肠组织肿瘤坏死因子(TNF-α)和白细胞介素-6(IL-6)mRNA相对表达量,电镜观察肠上皮细胞的结构,蛋白电泳和免疫组织化学染色法检测小鼠结肠组织E-cadherin和occludin蛋白表达量。结果 与青年组比较,老年DSS小鼠体质量下降更明显(t=3.679,P=0.006),疾病活动指数更高(t=2.496,P=0.037),病理表现更严重(U=0.000,P=0.008)及IL-6表达增加(U=4.000,P=0.191)。电镜观察老年对照组肠上皮细胞间的紧密连接结构不连续,老年和青年DSS小鼠肠上皮细胞间紧密连接结构模糊,破坏明显。老年实验组小鼠结肠组织E-cadherin(t=0.184,P=0.863)和occludin表达(t=0.399,P=0.710)低于青年实验组。结论 衰老会加重DSS诱发的小鼠结肠炎,其机制可能与衰老相关的肠上皮细胞紧密连接、黏附连接损伤,使肠黏膜屏障功能减退有关。

Effect of Aging on Experimental Colitis in Mice and Its Associated Mechanism

Objective To explore whether aging increases severity of colitis in mice and its mechanism.Methods Young (6-8 weeks)and aged (56 weeks) C57Bl/6 mice were divided into the control and experimental group (n=5,each). Dextran sodium sulfate(DSS) was used to induce acute colitis mouse model in the experimental group.The mRNA expressions of tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6)in colon were measured by RT-PCR. Tight junctions (TJs) of intestinal epithelial cells was examined by transmission electron microscopy (TEM). Protein expressions of E-cadherin and occludin were detected by Western blotting and immunohistochemistry in colon.Results Compared with the young DSS-induced mice,the aged DSS-induced mice had more weight loss(t=3.679,P=0.006),higher disease indexes (t=2.496,P=0.037),higher histologic scores(U=0.000,P=0.008) and higher colonic IL-6 level (U=4.000,P=0.191). The TJs of intestinal epithelial cells were discontinuous in old healthy rats,and the TJs were destroyed significantly in both young and aged DSS-induced mice. Compared with the young DSS-induced mice,the aged DSS-induced mice had decreased protein expressions of E-cadherin (t=0.184,P=0.863)and occludin (t=0.399,P=0.710).Conclusions Aging leads to more severe disease following DSS challenge. Age-related deterioration in the functions of the gastrointestinal barrier and integrity may be one of the possible mechanisms.