Department of Molecular Biomedicine, CINVESTAV-IPN, Mexico City, Mexico.
Department of Cell Biology, CINVESTAV-IPN, Mexico City, Mexico.
Front Cell Infect Microbiol. 2022 May 30;12:885191. doi: 10.3389/fcimb.2022.885191. eCollection 2022.
Typical enteroaggregative (tEAEC) is a diarrheagenic pathotype associated with pediatric and traveler's diarrhea. Even without diarrhea, EAEC infections in children also lead to increased gut inflammation and growth shortfalls. EAEC strain's defining phenotype is the aggregative adherence pattern on epithelial cells attributable to the aggregative adherence fimbriae (AAF). EAEC only causes diarrhea in humans; therefore, not much is known of the exact intestinal region of infection and damage or its interactions with intestinal enterocytes and . This study aimed to develop a new tEAEC mouse model of infection, characterize the microbiota of infected mice, and evaluate the expression of host adherence and surface molecules triggering EAEC infection and the role of the EAEC AAF-II in adherence. Six-week-old C57BL/6 mice, without previous antibiotic treatment, were orally challenged with EAEC 042 strain or EAEC 042 AAF-II mutant (ΔAAF/II) strain, or DAEC-MXR strain (diffusely adherent clinical isolate), and with saline solution (control group). Paraffin sections of the colon and ileum were stained with H&E and periodic acid-Schiff. ZO-1, β-catenin, MUC1, and bacteria were analyzed by immunofluorescence. EAEC-infected mice, in comparison with DAEC-MXR-infected and control mice, significantly lost weight during the first 3 days. After 7 days post-infection, mucus production was increased in the colon and ileum, ZO-1 localization remained unaltered, and morphological alterations were more pronounced in the ileum since increased expression and apical localization of β-catenin in ileal enterocytes were observed. EAEC-infected mice developed dysbiosis 21 days post-infection. At 4 days post-infection, EAEC strain 042 formed a biofilm on ileal villi and increased the expression and apical localization of β-catenin in ileal enterocytes; these effects were not seen in animals infected with the 042 ΔAAF/II strain. At 3 days post-infection, MUC1 expression on ileal enterocytes was mainly detectable among infected mice and colocalized with 042 strains on the enterocyte surface. We developed a novel mouse model of EAEC infection, which mimics human infection, not an illness, revealing that EAEC 042 exerts its pathogenic effects in the mouse ileum and causes dysbiosis. This model is a unique tool to unveil early molecular mechanisms of EAEC infection and .
典型肠聚集性（tEAEC）是一种与儿科和旅行者腹泻相关的致腹泻病原体。即使没有腹泻，EAEC 感染也会导致儿童肠道炎症增加和生长发育迟缓。EAEC 菌株的定义表型是上皮细胞上的聚集粘附模式，归因于聚集粘附菌毛（AAF）。EAEC 仅在人类中引起腹泻；因此，对于确切的感染和损伤部位或其与肠道肠细胞的相互作用知之甚少。本研究旨在开发一种新的 tEAEC 小鼠感染模型，描述感染小鼠的微生物群，并评估宿主粘附和表面分子触发 EAEC 感染的表达以及 EAEC AAF-II 在粘附中的作用。没有先前抗生素治疗的 6 周龄 C57BL/6 小鼠经口用 EAEC 042 株或 EAEC 042 AAF-II 突变体（ΔAAF/II）株或 DAEC-MXR 株（弥漫粘附临床分离株）和盐水溶液（对照组）挑战。用 H&E 和过碘酸-Schiff 染色对结肠和回肠的石蜡切片进行染色。通过免疫荧光分析 ZO-1、β-连环蛋白、MUC1 和细菌。与 DAEC-MXR 感染和对照小鼠相比，感染 EAEC 的小鼠在最初 3 天体重明显减轻。感染后 7 天，结肠和回肠中粘液生成增加，ZO-1 定位保持不变，回肠中形态改变更为明显，因为观察到回肠肠细胞中 β-连环蛋白的表达和顶端定位增加。感染 EAEC 的小鼠在感染后 21 天发生菌群失调。感染后 4 天，EAEC 042 株在回肠绒毛上形成生物膜，并增加回肠肠细胞中 β-连环蛋白的表达和顶端定位；在感染 042ΔAAF/II 株的动物中未观察到这些效应。感染后 3 天，回肠肠细胞中 MUC1 的表达主要在感染小鼠中检测到，并与肠细胞表面的 042 株共定位。我们开发了一种新的 EAEC 感染小鼠模型，模拟人类感染，而不是疾病，表明 EAEC 042 在小鼠回肠中发挥其致病作用并导致菌群失调。该模型是揭示 EAEC 感染早期分子机制的独特工具。
