IL-17在黏附侵袭性大肠杆菌感染小鼠结肠过程中的作用机制研究

目的:评价IL-17在黏附侵袭性大肠杆菌感染小鼠结肠过程中的作用及其可能机制。方法:选择野生型及IL-17基因敲除的SPF级C57BL/6小鼠并随机分成4组,分别给予不同的处理:(1)野生小鼠+单纯蒸馏水灌胃处理组;(2)野生小鼠+E.coli LF82(1×109/CFU/只)灌胃10天处理组;(3)IL-17敲除小鼠+单纯蒸馏水灌胃处理组;(4)IL-17敲除小鼠+E.coli LF82灌胃10天处理组。从以下5个方面评价各组小鼠的炎症反应和IL-17水平:(1)组织病理评分评估炎症反应严重程度;(2)透射电镜下观察结肠上皮细胞的超微结构;(3)免疫组织化学检测结肠分泌的IL-17;(4)PCR检测小鼠结肠中IL-17m RNA表达;(5)ELISA检测结肠组织中IL-17的含量。结果:定植了E.coli LF82的IL-17敲除小鼠肠道炎症程度和超微结构损伤较野生型小鼠更加严重(P0.05)。与未经E.coli LF82处理组相比,定植了E.coli LF82的野生小鼠肠道中IL-17m RNA和IL-17含量明显升高(P0.05)。结论:IL-17在E.coli LF82在黏附侵袭结肠粘膜过程中的保护作用,IL-17是针对AIEC菌株E.coli LF82免疫的重要效应物,而结肠局部分泌增加的IL-17会改善感染的结果。

The Role and Mechanism of IL-17 in the Colon Infected by Adherent Invasive Escherichia coli LF82

ABSTRACT Objective: To assess the role of IL-17 in the colon of mice infected by adherent-invasive Escherichia coli (AIEC) strain E.coli LF82. Methods: The wild-type (WT) mice and IL-17KO (IL-17 knockout) mice placed in specific pathogen free (SPF) housing were randomly divided into 4 groups: (1) WT mice + distilled water; (2) WT mice + E. coli LF82 by oral gavage for 10 days; (3) IL-17KO mice + distilled water; (4) IL-17KO mice + E.coli LF82 by oral gavage for 10 days. Four aspects of the treatment response were evaluated in each group: (1) histological score; (2) transmission electron microscope (TEM) to explore the ultrastructure; (3) the secretion of IL-17 detected by immune histochemistry; (4) the relative quantitative analysis of IL-17 in the colon detected by RT-PCR; (5) the quantitative analysis of IL-17F in the colon detected by ELISA. Results: Compared with non-treatment group, the expression of IL-17 mRNA and the activity of IL-17 were significantly higher than that in WT mice (P<0.05). After E. coli LF82 treatment, compared with WT mice, the histological score and the ultrastructure in IL-17KO mice improved significantly (P<0.05). Conclusion: IL-17 protects colonic epithelial integrity in the colon infected by adherent invasive Escherichia coli LF82. IL-17 is an important effector of immunity to AIEC strain E.coli LF82, suggestting that an increased local production of IL-17 would improve the outcome of infection.