Faecalibacterium prausnitzii治疗大鼠TNBS结肠炎的机制研究

Mechanism of Faecalibacterium prausnitzii in Treating TNBS-induced Colitis in Rats

背景:NLRP3炎症小体在炎症性肠病中的作用受到广泛关注。Faecalibacterium prausnitzii(Fp)是一种具有抗炎作用的共生菌,研究显示其对大鼠结肠炎具有防治作用。目的:探讨Fp治疗大鼠实验性结肠炎的可能机制。方法:50只大鼠随机分为对照组(n=10)和模型组(n=40),模型组以5%TNBS和无水乙醇灌肠诱导结肠炎,造模24 h后随机分为PBS组、介质组、Fp活菌组和Fp上清组,每天予相应成分1 mL灌胃,连续7 d。第8天处死动物,评估结肠炎症程度,以蛋白质印迹法和real-time PCR检测NLRP3炎症小体组分NLRP3、ASC、caspase-1表达;分别以real-time PCR和ELISA法检测结肠和血浆NLRP3炎症小体下游效应分子IL-1β、IL-18水平。结果:模型组大鼠存在不同程度的体质量减轻、结肠缩短和结肠炎症损伤,Fp活菌组和Fp上清组上述表现较PBS组和介质组明显减轻。PBS组和介质组结肠组织NLRP3、ASC、caspase-1蛋白和mRNA表达显著高于对照组(P<0.05),结肠和血浆IL-1β水平增高(P<0.05),IL-18水平降低(P<0.05)。Fp活菌组和Fp上清组IL-18水平较PBS组和介质组进一步降低(P<0.05),其余参数增高趋势均明显改善(P<0.05)。结论:NLRP3炎症小体参与介导TNBS大鼠结肠炎发生,而Fp可通过抑制NLRP3炎症小体及其下游效应分子而减轻结肠炎症。

Background：NLRP3 inflammasome attracts widespread attention in study of inflammatory bowel disease. Faecalibacterium prausnitzii（Fp）is an anti-inflammatory commensal bacterium that has preventive and therapeutic effects on rat colitis. Aims：To explore the underlying mechanism of Fp in treating experimental colitis in rats. Methods：Fifty rats were randomly divided into two groups,10 in control group and 40 in model group. Rats in model group were administered intrarectally with 5% TNBS and dehydrated alcohol to induce experimental colitis. Twenty-four hours afterwards,the model rats were further divided into four groups and administered intragastrically with PBS,culture medium,live Fp and Fp supernatant 1 mL per day,respectively,for 7 days. On day 8,all the rats were sacrificed for evaluation of colonic inflammation. Expressions of the constituents of NLRP3 inflammasome（NLRP3,ASC,and caspase-1）were assessed by Western blotting and real-time PCR;levels of IL-1β and IL-18,the downstream effectors of NLRP3 inflammasome,in colon and plasma were measured by real-time PCR and ELISA,respectively. Results：Weight loss, reduced colon length and colonic inflammatory injury were observed in model rats. These manifestations were ameliorated in live Fp and Fp supernatant groups than those in PBS and culture medium groups. In PBS and culture medium groups, expressions of NLRP3,ASC,and caspase-1 protein and mRNA in colonic tissue were significantly higher than those in control group（P 〈 0. 05）,the colonic and plasma levels of IL-1β were increased（P 〈 0. 05）,and IL-18 levels were＆nbsp;decreased（P 〈 0. 05）. In live Fp and Fp supernatant groups,IL-18 level showed a further reduction as compared with PBS and culture medium groups（ P 〈 0. 05）,but the increasing trend for other parameters was reduced（ P 〈 0. 05）. Conclusions：NLRP3 inflammasome participates in the development of TNBS-induced colitis in rats. Fp might alleviate colonic inflammation by inhibiting NLRP3 inflammasome and its downstream effectors.