D'Arienzo Rossana, Maurano Francesco, Mazzarella Giuseppe, Luongo Diomira, Stefanile Rosita, Ricca Ezio, Rossi Mauro
Istituto di Scienze dell'Alimentazione, CNR, via Roma 52, 83100 Avellino, Italy.
Res Microbiol. 2006 Nov;157(9):891-7. doi: 10.1016/j.resmic.2006.06.001. Epub 2006 Sep 26.
The present work was aimed at investigating whether Bacillus subtilis spores, widely used in probiotic as well as pharmaceutical preparations for mild gastrointestinal disorders, can suppress enteric infections. To address this issue, we developed a mouse model of infection using the mouse enteropathogen Citrobacter rodentium, a member of a family of human and animal pathogens which includes the clinically significant enteropathogenic (EPEC) and enterohemorrhagic (EHEC) Escherichia coli strains. This group of pathogens causes transmissible colonic hyperplasia by using attaching and effacing (A/E) lesions to colonize the host colon. Because of its similarities to human enteropathogens, C. rodentium is now widely used as an in vivo model for gastrointestinal infections. Swiss NIH mice were orally administered B. subtilis spores one day before infection with C. rodentium. Mice were sacrificed on day 15 after infection, and distal colon, liver and mesenteric lymph nodes were removed for bacteria counts, morphology, immunohistology and IFNgamma mRNA analysis. We observed that spore predosing was effective in significantly decreasing infection and enteropathy in suckling mice infected with a dose of C. rodentium sufficient to cause colon colonization, crypt hyperplasia and high mortality rates. Moreover, in mice predosed with spores, the number of CD4(+) cells and IFNgamma transcript levels remained high. These results thus indicate that our newly established model of C. rodentium infection is a suitable system for analyzing the effects of probiotic bacteria on enteroinfections and that B. subtilis spores are efficient at reducing C. rodentium infection in mice, leaving unaltered the immune response against the pathogen.
本研究旨在调查广泛用于益生菌以及治疗轻度胃肠道疾病的药物制剂中的枯草芽孢杆菌孢子是否能抑制肠道感染。为解决这个问题，我们利用小鼠肠道病原体鼠柠檬酸杆菌建立了一种感染小鼠模型，该菌是人和动物病原体家族的成员，其中包括具有临床意义的肠致病性大肠杆菌（EPEC）和肠出血性大肠杆菌（EHEC）菌株。这组病原体通过使用黏附与抹除（A/E）损伤来定殖于宿主结肠，从而导致传染性结肠增生。由于其与人类肠道病原体相似，鼠柠檬酸杆菌现在被广泛用作胃肠道感染的体内模型。在感染鼠柠檬酸杆菌前一天，给瑞士NIH小鼠口服枯草芽孢杆菌孢子。感染后第15天处死小鼠，取出远端结肠、肝脏和肠系膜淋巴结进行细菌计数、形态学、免疫组织学和IFNγ mRNA分析。我们观察到，预先给予孢子可有效显著降低感染剂量足以导致结肠定殖、隐窝增生和高死亡率的哺乳期小鼠的感染和肠道病变。此外，在预先给予孢子的小鼠中，CD4(+)细胞数量和IFNγ转录水平仍然很高。因此，这些结果表明，我们新建立的鼠柠檬酸杆菌感染模型是分析益生菌对肠道感染影响的合适系统，并且枯草芽孢杆菌孢子在降低小鼠鼠柠檬酸杆菌感染方面是有效的，同时不会改变对病原体的免疫反应。
