益生菌对结肠炎大鼠黏膜细胞因子表达的影响

Effects of probiotics on the gut flora and mucosal tumor necrosis factorαexpression in rats with experimental colitis

目的探讨益生菌对实验性结肠炎大鼠肠道炎症、菌群及黏膜肿瘤坏死因子（TNF）-α表达的影响。方法建立2，4，6-三硝基苯磺酸（TNBS）实验性结肠炎大鼠模型，30只Wistar大鼠均分为正常对照组（NC组）、模型对照组（UC组）和益生菌治疗组（PC组）。PC组大鼠采用双歧三联活菌悬液（2．2×10^9CFU／只）灌胃治疗，1次／d，共4周，光镜下观察肠黏膜炎症并评分，检测各组大鼠部分肠道菌群、肠黏膜中TNF-α、白细胞介素（IL）-6表达及血浆内毒素水平，分析其变化。结果PC组大鼠结肠炎症评分较UC组明显改善（7．94±0．85比10．25±1．36，P〈0．05），但未恢复至NC组水平（7．94±0．85比4．35±0．88，P〈0．01）。PC组肠道内乳酸杆菌和双歧杆菌较UC组明显增加，大肠杆菌和真菌则减少（P〈0．05）。PC组血浆内毒素、TNF-α水平较UC组降低[内毒素：（93．33±21．22）pg／ml比（121．25±39．07）pg／ml；TNF-α：67．51±14．63比85．99±18．17，P值均〈0．05]，但高于NC组[内毒素：（93．33±21．22）pg／ml比（35．20±15．12）pg／ml；TNF-α：67．51±14．63比43．28±19．98，P值均〈0．01]。与UC组比较，PC组IL-6水平有所降低，但差异无统计学意义（155．22±34．01比184．09±29．11，P〉0．05），且高于NC组（155．22±34．01比108．73±37．35，P〈0．01）。结论双歧三联活菌可调整肠道菌群紊乱，减轻大鼠结肠炎症，改善菌群紊乱、减少内毒素吸收及局部促炎性细胞因子的分泌。

Objective To evaluate the effects of probiotics on inflammation, intestinal flora and mucosal tumor necrosis factor alpha（TNF-α） expression in experimental colitis rats. Methods Thirty Wistar rats were randomly divided into normal control group（NC）, model control group（UC）, and pro biotics treatment group （PC）. The experimental colitis were induced by trinitrobenzene sulfonic acid （TNBS）/ethanol enema. Rats in PC group were fed with Bifico [live probiotics of combined bifidobacterium（Bif）, lactobacillus （Lac） and enterococcus] by 2. 2 × 10^9 colony-forming unit （CFU）/d for 4 weeks. Inflammatory scores and mucosal morphological changes under light microscopy were studied. Plasma endotoxin levels, expressions of TNF-α and interleukin-6 （IL-6） in mucosa were measured. Enteric microorganisms in cecum were fostered with standard methods. Results Inflammatory scores in PC group decreased compared with those in UC group（7.94 ± 0.85 vs 10.25 ± 1.36, P 〈 0.05）, but still higher than those in NC group（7.94 ± 0.85 vs 4.35 ± 0.88, P 〈 0.01）. There was a significant alteration in the enteric microbial flora, Bif and Lac were decreased significantly in UC group, Bifico supplement ameliorated this imbalance. Plasma endotoxin and mucosal TNF-α levels in PC were lower than those in UC group[endotoxin.. （93.33 ± 21.22）pg/ml vs （ 121.25 ± 39.07）pg/ml; TNF-α： 67.51 ± 14.63 vs 85.99 ± 18.17, P 〈 0. 053, but higher than those in NC group[endotoxin： （93.33 ± 21.22）pg/ml vs （35.20±15. 12）pg/ml; TNF-α： 67.51± 14.63 vs 43.28± 19.98, P 〈 0.01]. There was no statistically significant difference in mucosal IL-6 levels between PC group and UC group, though its level in PC group was lower than that in UC group（155.22±34.01 vs 184.09±29.11, P〈 0.05）, but higher than that in NC group（155. 22 ± 34. 01 vs 108. 73 ±37. 35, P〈0. 01）. Conclusions Probiotics can attenuate inflammation of experimental colitis of rats through reinstituting gut flora balance. Improving gut flora imbalance, reducing endotoxin and pro inflammatory cytokines may be the effects of probiotics.