凝结魏茨曼氏菌BC-G44对大鼠抗生素相关性腹泻结肠菌群结构、屏障功能及炎症反应的影响

Weizmannia coagulans BC-G44 regulates intestinal microbiota structure, barrier function, and inflammatory response in the colon of the rat model of antibiotic-associated diarrhea

摘要:

目的 探究凝结魏茨曼氏菌(Weizmannia coagulans) BC-G44对抗生素相关性腹泻(antibiotic-associated diarrhea, AAD)大鼠模型结肠菌群结构、屏障功能和炎症反应的影响。方法 选取30只5周龄、体重相近的Sprague-Dawley (SD)大鼠，随机分为对照组(Con组)、模型组(Mod组)、低剂量凝结魏茨曼氏菌组(LBC-G44组)、中剂量凝结魏茨曼氏菌组(MBC-G44组)和高剂量凝结魏茨曼氏菌组(HBC-G44组)等5组(n=6)，试验包括建模期(7 d)和恢复期(12 d)。在建模期，Con组大鼠每天灌胃2 mL生理盐水，Mod、LBC-G44、MBC-G44和HBC-G44组大鼠则灌胃含克林霉素、氨苄西林和链霉素的混合溶液(2 mL/d)以诱导AAD。在恢复期，Con和Mod组继续灌胃生理盐水，而LBC-G44、MBC-G44和HBC-G44组分别灌胃10⁷、10⁸和10⁹ CFU/d的W. coagulans BC-G44悬液。在第19天，采集结肠组织进行组织学观察，测定结肠黏膜中细胞因子含量、屏障蛋白和炎症相关基因的表达水平。此外，还分析结肠食糜中的微生物组成和代谢物。结果 在建模期第7天，与Con组相比，Mod、LBC-G44、MBC-G44和HBC-G44组大鼠出现显著腹泻、体重下降和采食量减少的现象(P<0.05)；在第19天，与Mod组对比，MBC-G44和HBC-G44组结肠黏膜厚度和杯状细胞数量显著增加(P<0.05)。HBC-G44组结肠食糜中拟杆菌属(Bacteroides)的相对丰度和乳酸浓度提高(P<0.05)，结肠黏膜中d-乳酸(d-lactic acid, d-LA)和二胺氧化酶(diamine oxidase, DAO)浓度也提高(P<0.05)，结肠黏膜中Claudin-1、Occludin和MUC2的相对mRNA表达量上调(P<0.05)。同时，与Mod组相比，MBC-G44和HBC-G44组结肠黏膜中Toll样受体4 (Toll-like receptor 4, TLR4)和核因子κB (nuclear factor-kappa B, NF-κB)基因的相对mRNA表达量下调(P<0.05)，且结肠黏膜中肿瘤坏死因子-α (tumor necrosis factor-α, TNF-α)和白细胞介素-1β (interleukin-1 beta, IL-1β)含量降低(P<0.05)。结论 W. coagulans BC-G44能够改善抗生素诱导的大鼠结肠损伤，调节结肠微生物群组成和代谢产物，增强肠道屏障功能并减轻肠道炎症反应，从而有效缓解AAD症状。

关键词:凝结魏茨曼氏菌BC-G44;大鼠;抗生素相关性腹泻;菌群结构;屏障功能;炎症反应

Abstract:

Objective To investigate the effects of Weizmannia coagulans BC-G44 on the intestinal microbiota structure, barrier function, and inflammatory response in the colon of the rat model of antibiotic-associated diarrhea (AAD).Methods A total of 30 five-week-old Sprague-Dawley (SD) rats with similar body weights were randomized into five groups (n=6): control (Con), model (Mod), low-dose W. coagulans BC-G44 (LBC-G44), medium-dose W. coagulans BC-G44 (MBC-G44), and high-dose W. coagulans BC-G44 (HBC-G44). The experiment encompassed a modeling period (7 days) and a recovery period (12 days). During the modeling period, rats in the Con group were administrated with normal saline at 2 mL/d by gavage, while those in the Mod, LBC-G44, MBC-G44, and HBC-G44 groups were administrated with a mixture containing clindamycin, ampicillin, and streptomycin (2 mL/d) by gavage to induce AAD. During the recovery period, the Con and Mod groups continued to receive normal saline, while the LBC-G44, MBC-G44, and HBC-G44 groups received W. coagulans BC-G44 suspensions at 10⁷, 10⁸, and 10⁹ CFU/d, respectively. On day 19, colonic tissue samples were collected for histological examination, and the concentrations of cytokines, and the expression levels of barrier proteins and inflammation-related genes in the colonic mucosa were measured. Furthermore, the microbiota composition and metabolites in the colonic chyme were analyzed.Results On day 7 of modeling, rats in the Mod, LBC-G44, MBC-G44, and HBC-G44 groups exhibited diarrhea, weight losses, and reduced food intake compared with those in the Con group (P<0.05). On day 19, compared with the Mod group, the MBC-G44 and HBC-G44 groups showed increases in the colonic mucosa thickness and goblet cell number (P<0.05). The HBC-G44 group showed increased relative abundance of Bacteroides and concentrations of lactate in the colonic chyme (P<0.05), elevated levels of d-lactic acid (d-LA) and diamine oxidase (DAO) in the colonic mucosa, and up-regulated relative mRNA levels of Claudin-1, Occludin, and MUC2 in the colonic mucosa (P<0.05). Meanwhile, compared with the Mod group, the MBC-G44 and HBC-G44 groups showed down-regulated relative mRNA levels of Toll-like receptor 4 gene (TLR4) and nuclear factor-kappa B gene (NF-κB) (P<0.05), and reduced concentrations of tumor necrosis factor (TNF)-α and interleukin (IL)-1β (P<0.05) in the colonic mucosa.Conclusion W. coagulans BC-G44 can ameliorate antibiotic-induced colonic injury, regulate the colonic microbiota composition and metabolites, enhance intestinal barrier function, and reduce intestinal inflammatory responses in rats, thus alleviating the symptoms of AAD.

Key words:Weizmannia coagulans BC-G44;rats;antibiotic-associated diarrhea;microbiota structure;barrier function;inflammatory response