CD8+T细胞在葡聚糖硫酸钠诱导的小鼠急性结肠炎中的致病性研究

Pathogenesis of CD8^+ T cells in dextran sulfate sodium-induced murine acute colitis

目的·通过葡聚糖硫酸钠(dextran sulfate sodium,DSS)诱导的小鼠急性结肠炎模型,观察CD8+T细胞在小鼠急性结肠炎发病中的作用。方法·给予野生型C57BL/6小鼠和CD8敲除(CD8-/-)小鼠饮用质量浓度为2%的DSS溶液诱导急性结肠炎模型,观察体质量动态变化、结肠长度及病理改变、肠炎疾病活动度变化。诱导10 d后收集小鼠远端结肠,抽提总RNA,采用实时荧光定量PCR检测肠炎小鼠结肠组织中炎症细胞因子Il1b、Il6、Il17a、Ifng、Tnf、Il10和Tgfb1 mRNA表达水平。通过苏木精-伊红(H-E)染色评估结肠组织病理学改变,通过免疫荧光染色观察结肠组织中CD8+T细胞的浸润情况。采用质量浓度为3%和4%的DSS溶液诱导肠炎后观察小鼠存活率。结果·2%DSS诱导急性结肠炎后,CD8-/-小鼠体质量下降速度较慢,在第9日呈现上升趋势,CD8-/-小鼠结肠组织病理改变较轻;与野生型小鼠比较,CD8-/-小鼠结肠中促炎症细胞因子Il1b、Il6、Il17a、Ifng和Tnf mRNA表达水平较低(均P<0.05)。使用2%DSS诱导结肠炎后第10日,免疫荧光染色检测结果显示,野生型小鼠肠道固有层中浸润大量CD8+T细胞,与未造模小鼠的差异具有统计学意义(P=0.001)。经3%和4%DSS诱导急性结肠炎后,WT小鼠存活率为37.5%和0,CD8-/-小鼠存活率为66.7%和100%;与WT小鼠比较,CD8-/-小鼠存活率高(P=0.025,P=0.001)。结论·CD8+T细胞促进DSS诱导的小鼠急性结肠炎的发生。

Objective · To investigate the role of CD8+ T cells in the pathogenesis of acute murine colitis induced by dextran sulfate sodium(DSS). Methods · Wild type and CD8 knock-out(CD8-/-) mice with C57 BL/6 background were given DSS with concentration of 2%(m/V). The body weight, colon length, pathological changes and disease activity of colitis were observed dynamically. The total RNA was extracted from the distal colon of mice after induction for 10 d. The mRNA expression of inflammatory cytokines Il1 b, Il6, Il17 a, Ifng, Tnf, Il10 and Tgfb1 were detected by real-time quantitative PCR. Colon tissue sections were stained with hematoxylin-eosin(H-E) and the changes of intestinal histopathology were evaluated, and the infiltration of CD8+ T cells in colon tissue was observed by immunofluorescence staining. The survival rate of mice was observed with 3% and 4%(m/V) DSS solutioninduced colitis models. Results · After CD8-/-mice being induced by 2% DSS, the body weight decreased slowly and showed an increasing trend on the 9 th day, while the pathological changes of colon tissues of CD8-/-mice were slight. The expression levels of Il1 b, Il6, Il17 a, Ifng and Tnf mRNA were lower than those of wild-type mice(P<0.05). The number of CD8+ T cells in colonic lamina propria of wild-type mice with 2% DSS induction was higher than that of wild-type mice without DSS treatment(P=0.001). The survival rates of wild-type mice induced by 3% and 4% DSS were 37.5% and 0, and the survival rates of CD8-/-mice were 66.7% and 100%, while the survival rates of CD8-/-mice receiving 3% and 4% DSS were higher than those of wildtype mice(P=0.025, P=0.001). Conclusion · CD8+ T cells can promote the development of murine acute DSS-induced colitis.