TLR4mAb对2,4,6-三硝基苯磺酸诱导的溃疡性结肠炎模型大鼠肠腔及肠黏膜菌群的影响

Effects of TLR4mAb on the luminal and mucosal microbiotas in rat models of ulcerative colitis

目的研究Toll样受体4单克隆抗体(TLR4mAb)在溃疡性结肠炎模型大鼠肠腔及肠黏膜内拟杆菌属、肠球菌属、乳酸杆菌属、双歧杆菌属、消化链球菌属及大肠埃希菌属含量变化中的作用。方法 30只SD大鼠随机分为对照组、UC模型组和TLR4mAb干预组。模型组、干预组采用三硝基苯磺酸(TNBS)造模,干预组造模当天给予TLR4mAb腹腔注射,第8天处死全部大鼠。留取结肠黏膜及粪便,用实时荧光定量PCR法测定所有标本中不同细菌含量。结果 (1)粪便标本:UC组较正常组大肠埃希菌、拟杆菌含量增加(P<0.017),乳酸杆菌、双歧杆菌、肠球菌含量减少(P<0.017),消化链球菌含量差异无统计学意义。TLR4mAb干预组较UC组,消化链球菌含量差异无统计学意义,其余目标菌含量均有所恢复(P<0.017)。TLR4mAb干预组较正常组目标菌含量差异均无统计学意义;(2)结肠黏膜标本:UC组较正常组乳酸杆菌、双歧杆菌含量无明显变化,其余目标菌含量均增加(P<0.017)。TLR4mAb干预组较UC组,乳酸杆菌、双歧杆菌含量无明显变化,其余目标菌含量均减少(P<0.017)。TLR4mAb干预组较正常组拟杆菌含量偏高(P<0.017),其余目标菌含量差异无统计学意义。结论 UC模型大鼠较正常组目标菌含量均存在变化,提示UC的发生与肠道菌群改变密切相关。TLR4mAb能改善UC模型大鼠相关菌群结构,提示Toll样受体4在UC发生及UC肠道菌群变化中可能具有双重调节作用。UC模型大鼠肠道粪便与黏膜标本中目标菌含量变化不同,提示UC的发生中肠道粪便及黏膜相关细菌的变化不一致。

Objective To study the effects of TLR4 mAb on the contents of Bacteroides,Enterococci,Lactobacilli,Bifidobacteria,Peptostreptococci and Escherichia coli in the luminal and mucosal microbiotas of rat models of ulcerative colitis（UC）.Methods 30 SD rats were randomly assigned into the normal control group,model group or TLR4 mAb group respectively.Trinitro benzene sulfonic acid（TNBS）was given to model group and TLR4 mAb group,then TLR4 mAb was given to TLR4 mAb group by injection the same day.All the rats were killed on the 8th day to collect faecal and sigmoid mucosa specimens,and bacterial DNAs were extracted to determine the numbers of bacteria with real-time PCR.Results（1）Luminal microbiotas：the contents of Escherichia coli and Bacteroides in model group were significantly higher than in the control group（P〈0.017）,while those of Lactobacilli,Bifidobacteriaand Enterococci decreased（P〈0.017）.There were no significant differences in the content of Peptostreptococci between model group and normal control group,and between the TLR4 mAb group and model group.The contents of other target bacteria in TLR4 mAb group were recovered（P〈0.017）,and the contents of the six bacteria in TLR4 mAb group were not significantly different from those in normal control group.（2）Mucosal microbiotas：there were no significant difference in the contents of Lactobacilli and Bifidobacteria between model group and control group,while the contents of other target bacteria increased（P〈0.017）.There were no significant differences in the contents of Lactobacilli and Bifidobacteria between TLR4 mAb group and model group,while the contents of other target bacteria decreased（P〈0.017）.The content of Bacteroidesin TLR4 mAb group was higher than in control group,while the contents of other five bacteria had no obvious differences.Conclusion There are significant changes in the luminal and mucosal microbiotas of rat models of UC,suggesting that the occurrence of UC is closely related to the changes of intestinal flora.TLR4 mAb improved the structure of intestinal flora of UC rats,suggesting that TLR4 may play an important role in the occurrence of UC and regulation of the structure of intestinal flora.The contents of the target bacteria in luminal microbiotas are different from those in mucosal microbiotas,which suggests that the changes in the luminal microbiotas may not be consistent with the changes in mucosal microbiotas during the occurrence of UC.