Department of Pediatrics, University of Virginia, Charlottesville, Virginia, USA
Department of Pediatrics, University of Virginia, Charlottesville, Virginia, USA.
Infect Immun. 2020 Aug 19;88(9). doi: 10.1128/IAI.00176-20.
Symptomatic and asymptomatic infection with the diarrheal pathogen enteroaggregative (EAEC) is associated with growth faltering in children in developing settings. The mechanism of this association is unknown, emphasizing a need for better understanding of the interactions between EAEC and the human gastrointestinal mucosa. In this study, we investigated the role of the aggregative adherence fimbriae II (AAF/II) in EAEC adherence and pathogenesis using human colonoids and duodenal enteroids. We found that a null mutant in , the major subunit of AAF/II, adhered significantly less than wild-type (WT) EAEC strain 042, and adherence was restored in a complemented strain. Immunofluorescence confocal microscopy of differentiated colonoids, which produce an intact mucus layer comprised of the secreted mucin MUC2, revealed bacteria at the epithelial surface and within the MUC2 layer. The WT strain adhered to the epithelial surface, whereas the deletion strain remained within the MUC2 layer, suggesting that the presence or absence of AAF/II determines both the abundance and location of EAEC adherence. In order to determine the consequences of EAEC adherence on epithelial barrier integrity, colonoid monolayers were exposed to EAEC constructs expressing or lacking Colonoids infected with WT EAEC had significantly decreased epithelial resistance, an effect that required AAF/II, suggesting that binding of EAEC to the epithelium is necessary to impair barrier function. In summary, we show that production of AAF/II is critical for adherence and barrier disruption in human colonoids, suggesting a role for this virulence factor in EAEC colonization of the gastrointestinal mucosa.
肠聚集性（EAEC）腹泻病原体的有症状和无症状感染与发展中国家儿童的生长发育迟缓有关。这种关联的机制尚不清楚，这强调了需要更好地了解 EAEC 与人类胃肠道黏膜之间的相互作用。在这项研究中，我们使用人结肠类器官和十二指肠类肠进行了研究，以调查聚集性粘附菌毛 II（AAF/II）在 EAEC 粘附和发病机制中的作用。我们发现，主要亚基缺失的突变体粘附性明显低于野生型（WT）EAEC 菌株 042，并且在互补菌株中恢复了粘附性。对分化的结肠类器官进行免疫荧光共聚焦显微镜检查，这些类器官产生由分泌型粘蛋白 MUC2 组成的完整黏液层，揭示了细菌在上皮表面和 MUC2 层内。WT 菌株附着在上皮表面，而 缺失菌株仍留在 MUC2 层内，这表明 AAF/II 的存在与否决定了 EAEC 粘附的丰度和位置。为了确定 EAEC 粘附对上皮屏障完整性的影响，将结肠类器官单层暴露于表达或缺乏 的 EAEC 构建体中。WT EAEC 感染的类肠细胞的上皮电阻明显降低，这一效应需要 AAF/II，表明 EAEC 与上皮的结合对于破坏屏障功能是必需的。总之，我们表明 AAF/II 的产生对于人结肠类器官的粘附和屏障破坏至关重要，这表明该毒力因子在 EAEC 对胃肠道黏膜的定植中起作用。
