益生菌治疗的实验性结肠炎中调节性T细胞的作用

The influence of T regulatory cells on experimental colitis of rate after treatment by probiotics

目的评价不同剂量益生菌对大鼠实验性结肠炎的疗效,研究治疗后全身及肠道局部调节性T细胞(Tr)的变化情况,探讨益生菌作用机制。方法建立三硝基苯磺酸(TNBS)实验性结肠炎大鼠模型。所用益生菌为双歧三联活菌(商品名:培菲康)。设阴性对照组、泼尼松组、柳氮磺胺吡啶 (SASP)组、益生菌小、大剂量组(剂量分别为150和300 mg·kg-1·d-1)、益生菌+泼尼松或SASP(益生菌剂量为150 mg·kg-1·d-1)组。治疗2周后组织学积分评定疗效;流式细胞仪检测各组外周血、脾脏和结肠上皮内CD4+CD25+及CD8+CD28-两种Tr比例变化。采用t检验行统计学分析。结果组织学评分显示大剂量益生菌对实验性结肠炎有效(2．2±0．8比3．5±0．7,P<0．05),而小剂量益生菌单独作用无明显疗效,联合泼尼松或SASP治疗比单独应用疗效更强;大剂量益生菌治疗后CD4+ CD25+Tr比例在外周血(3．4±0．6比11．7±4．7,P<0．05)及脾脏(2．1±1.9比10．3±3．1,P<0．05) 中下降,在结肠内上升(36．6±15．0比7．9±4．7,P<0．05);CD8+CD28-Tr则相反,在外周血及脾脏中上升(91．7±4．5比59．0±4．2,97．3±0．1比88．2±6．9,P<0．05),在结肠内下降(42．2±6．0比68．5 ±8．6,P<0．05)。Tr的这种变化与泼尼松或SASP治疗存在一定差异。结论益生菌单独大剂量或小剂量联合泼尼松或SASP治疗TNBS诱导的结肠炎有效,CD4+CD25+和CD8+CD28-Tr在发挥疗效过程中可能起一定作用。

Objective To evaluate the effects of probiotics on experimental colitis of rats and to explore systemic and local changes of T regulatory cells（Tr） after the treatment. Methods The models of experimental colitis were established by enema with 2,4,6-trinitrobenzenesulphonic acid （TNBS）. Live probiotics of combined bifidobacterium, lactobacillus and enterococcus （Bifico） were used. Four groups of rats were set up as negative group, TNBS alone group, probiotics group （high dosage and low dosage, with dose of 150 and 300 mg ·kg^-1·d^-1 respectively）, and combination group （probiotics plus prednisolone or sulfasalazine）. Histologic scoring was used to evaluate the effect of medications; the proportions of CD^＋CD25^＋ and CD8^＋ CD28^- Tr in peripheral blood, spleen mononuclear cells and intraepithelial lymphocytes of colon were detected by flow cytometry. Results Histopathology showed that high dosage of probiotics was effective in TNBS-induced colitis rats （2. 2±0.8 vs 3. 5±0. 7, P〈0. 05） ; while the effect of low dosage of probiotics alone was not significant, combined therapy had certain effect. Proportion of CD^＋ CD25^＋ Tr decreased in peripheral blood and spleen while increased in colon. In contrast, CD8^＋ CD28^- Tr increased in peripheral blood and spleen while decreased in colon. The above changes of Tr were distinguished from those with prednisolone or sulfasalazine treatment. Conclusions High dosage of probiotics alone or low dosage of probiotics in combination with prednisolone or sulfasalazine is effective in the management of TNBS-induced colitis in rats. CD^＋ CD25^＋ and CD8^＋ CD286- Tr may play a role in the effect of probiotics.