Objective: To investigate the effects of using Bifidobacterium bifidum TMC3115 in early life on intestinal microbiota and immune functions and the long-term impact on inflammatory bowel disease.
Methods: Fourteen pregnant BALB/c mice were purchased and 84 newborn BALB/c mice were subsequently obtained. Then, the newborn mice were randomly assigned to a normal saline (NS) group and a TMC3115 group, given via oral gavage normal saline and TMC3115, respectively, at a daily volume of 0.2 mL for each mouse. About 42 mice were assigned to each group. The gavage was stopped after 3 weeks. At this point, half of the mice in each group were sacrificed, and then the remaining mice in each group were randomly divided into NS-water group, NS-DSS group, TMC3115-water group, and TMC3115-DSS group, with about 10 mice in each group. The mice were given regular feed until the end of week 6 when they were given 3% dextran sulphate sodium (DSS) ad libitum for 4 days to establish the enteritis model, while the non-modeling groups were given pure water ad libitum. The experiment ended after 6 weeks and 4 days. The weekly body mass changes of the mice were documented. The intestinal tissue at the end of the experiment and the fecal samples, spleen and serum of the mice at 3 weeks and at the end of the experiment were collected to determine the pathology scores of colonic inflammation, the composition of fecal gut microbiota, spleen organ index and the mass concentration of serum cytokines.
Results: 1) At the end of the experiment, the inflammatory pathology score was significantly lower in the TMC3115-DSS group compared with that of the Saline-DSS group ( P<0.05), with less disruption of colonic crypt structures and other structures, less inflammatory infiltration, and more intact epithelial structures. 2) At 3 weeks, in comparison with those of the NS group, the relative abundance of Bifidobacteriumwas significantly higher in the feces of the TMC3115 ( P<0.05), the relative abundance of both Enterococcusand Staphylococcuswas lower ( P<0.05), the splenic organ index was significantly higher ( P<0.05), and interleukin (IL)-10 was significantly decreased ( P<0.05), while there was no significant change in IL-6 or TNF-α ( P>0.05). At the end of the experiment, in comparison with those of the NS-DSS group that undergone DSS induction, the TMC3115-DSS group had reduced relative abundance of Staphylococcus, Staphylococcus tumefaciens and Escherichia/ Shigellain the feces ( P<0.05), while the splenic organ index was significantly higher ( P<0.05), and there were no significant changes in IL-6 or TNF-α ( P>0.05).
Conclusion: The use of TMC3115 in early life promotes the construction of gut microbiota in neonatal mice, thereby producing a long-term effect that alleviates colitis in mice, but the mechanisms involved are still not fully understood.
目的: 探究生命早期使用两歧双歧杆菌（Bifidobacterium bifidum）TMC3115对肠道菌群及免疫功能和远期炎症性肠病的影响。
方法: 购入14只待产BALB/c孕鼠，获得新生BALB/c小鼠84只，随机分为生理盐水组和TMC3115组，每组约42只，分别采用生理盐水、TMC3115灌胃（每只灌胃量为0.2 mL/d ），至3周时停止灌胃。3周时，各组分别处死一半小鼠，随后将各组剩余小鼠随机分为生理盐水-water组、生理盐水-DSS组、TMC3115-water组、TMC3115-DSS组，每组约10只 。继续普通饲料喂养至6周时，自由饮用3%葡聚糖硫酸钠（dextran sulphate sodium, DSS）4 d建立肠炎模型，非模型组自由饮用纯水。6周零4天时，实验结束。记录小鼠每周体质量变化，分别采集实验结束时的肠道组织，以及3周和实验结束时小鼠的粪便样本、脾脏和血清，测定结肠炎症性病理评分、粪便肠道菌群构成、脾脏脏器指数和血清因子质量浓度。
结果: ①实验结束时，与生理盐水-DSS组相比，TMC3115-DSS组的结肠炎症性病理评分降低（P<0.05），结肠隐窝结构等破坏较小，炎性浸润程度较低，上皮结构较完整。②3周时，与生理盐水组相比，TMC3115组粪便中的双歧杆菌属相对丰度升高（P<0.05），肠球菌属和葡萄球菌属的相对丰度均降低（P<0.05），脾脏脏器指数升高（P<0.05），白细胞介素（interleukin, IL）-10下降（P<0.05），而IL-6和肿瘤坏死因子-α（tumor necrosis factor, TNF-α）无明显变化（P>0.05）；实验结束时，与生理盐水-DSS组相比，TMC3115-DSS组粪便中的葡萄球菌属、瘤胃球菌属和埃希氏杆菌属/志贺氏菌属相对丰度均降低（P<0.05），脾脏脏器指数升高（P<0.05），但IL-6、IL-10和TNF-α无明显变化（P>0.05）。
结论: 生命早期使用TMC3115可促进新生小鼠肠道菌群的构建，并产生远期影响，从而缓解小鼠结肠炎，但其机制尚不明确。
Keywords: Early life; Gut microbiota; Inflammatory bowel disease; TMC3115.
Copyright© by Editorial Board of Journal of Sichuan University (Medical Sciences).