嗜酸乳杆菌对小鼠溃疡性结肠炎模型的保护机制研究

Protective Mechanism of Lactobacillus acidophilus on DSS-induced Ulcerative Colitis in Mice

目的:探究嗜酸乳杆菌对葡聚糖硫酸钠(dextran sulfate sodium,DSS)诱导小鼠溃疡性结肠炎(ulcerative colitis,UC)模型的保护作用及机制。方法:40只小鼠随机均分为空白组、模型组、阳性药组和菌液组。空白组正常饲喂,其余各组均给予DSS制备模型。模型组灌胃生理盐水,阳性药组灌胃柳氮磺胺吡啶,菌液组灌胃嗜酸乳杆菌菌液。观察小鼠生理变化,进行疾病活动指数(disease activity index,DAI)评分,7天后处死小鼠后进行结肠组织HE染色观察,免疫组化和实时荧光定量PCR(real-time fluorescence quantitative PCR,qRT-PCR)法检测相关基因表达量。结果:与模型组相比较,菌液组和阳性药组体重降低情况显著改善(P<0.05),DAI评分显著降低(P<0.01),结肠黏膜腺体完整度较模型组好,结肠组织白细胞介素6(Interleukin 6,IL-6)、磷酸化细胞信号传导与转录活化因子3(phosphorylated cell signal transduction and transcription activator 3,p-STAT3)蛋白表达减少。菌液组和阳性药组微小RNA-214(microRNA-214,miR-214)、IL-6、肿瘤坏死因子α(tumor necrosis factor α,TNF-α)基因表达量均较模型组降低(P<0.01),人第10号染色体缺失的磷酸酶及张力蛋白同源的基因(phosphatase and tensin homologue deleted on chromosome 10,PTEN)和PDLIM2(PDZ and LIM domain 2)基因则较模型组提高(P<0.01)。结论:嗜酸乳杆菌对DSS诱导小鼠溃疡性结肠炎有较好的缓解作用,其机制是通过下调miR-214表达,进而抑制PDLIM2和PTEN通路,降低IL-6、TNF-α等炎症因子表达,改善炎症反应。

Objective: To investigate the protective effect and mechanism of Lactobacillus acidophilus on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice. Methods: Mice were randomly divided into control group, model group, positive group and bacterial suspension group. Mice in the control group were fed normally. DSS were given in the other groups. Normal saline was given in the model group and sulfasalazine was given in the positive group. Mice in the bacterial suspension group were administered with Lactobacillus acidophilus. The physiological changes of mice were observed and the disease activity index (DAI) scores were scored. After 7 days, the mice were sacrificed, colon tissues were collected for HE staining, immunohistochemistry and real-time quantitative PCR (qRT-PCR) were used to detect the expression of related genes. Results: Compared with those of the model group, mice in the bacterial suspension group and the positive group showed less weight loss (P<0.05), lower DAI scores (P<0.01), better colonic mucosal glands, lower expression of IL-6 and p-STAT3 protein in colon tissues, lower levels of miR-214, IL-6 and TNF-α(P<0.01) and higher levels of the PTEN gene and PDLIM2 gene (P<0.01). Conclusion: Lactobacillus acidophilus has a good alleviation effect on DSS-induced UC in mice. The mechanism is to down-regulate the expression of miR-214, thereby inhibiting PDLIM2 and PTEN pathways, decreasing the expression of IL-6 and TNF-α, and improving the inflammatory response.