Acid and bile-salt stress of enteropathogenic Escherichia coli enhances adhesion to epithelial cells and alters glycolipid receptor binding specificity
Acid and bile-salt stress of enteropathogenic Escherichia coli enhances adhesion to epithelial cells and alters glycolipid receptor binding specificity
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DOI：
10.1086/462422
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发表时间：
2005-10-15
影响因子：
6.4
通讯作者：
Foster, DEB
中科院分区：
文献类型：
--
作者：
de Jesus, MC;Urban, AA;Foster, DEB
背景资料。肠致病性大肠埃希菌(EPEC)是一种致泻病原菌，在摄食过程中暴露于应激状态，但应激对EPEC-宿主细胞黏附的影响却知之甚少。细菌应激前后用平板计数法检测EPEC与人上皮细胞的粘附性。应激处理包括暴露于低pH(有或无酸适应)和暴露于4种生理浓度的肠道胆盐。免疫印迹和流式细胞仪分析应激后细菌粘附素的表达。用薄层层析法测定细菌与脂质的结合力。短暂的低pH应激(有或无酸适应)和胆盐应激导致EPEC与宿主细胞的黏附显著增加。红霉素处理消除了粘附性增强，提示蛋白质合成是必需的。免疫印迹和流式细胞仪分析表明，在任一应激后，已知的粘附素的表达几乎没有变化。然而，我们发现酸应激后EPEC表面热休克蛋白70(Hsp70)的表达增加，用抗Hsp70抗体预处理可消除酸应激后的粘附性增强。酸休克还与应激后与磺基半乳糖神经酰胺结合增加有关，后者可能是其他病原体的受体。EPEC的酸/胆盐应激显著增强与宿主细胞的黏附，一对新的粘附素-受体对可能在这种黏附中发挥作用。
Background. Enteropathogenic Escherichia coli (EPEC), a diarrheagenic pathogen, is exposed to stress during ingestion, and yet little is known about the impact of stress on EPEC-host cell adhesion.Methods. EPEC adhesion to human epithelial cells was assessed by plate-count assay before and after bacterial stress. Stress treatments included exposure to low pH ( with or without acid adaptation) and exposure to physiological concentrations of 4 intestinal bile salts. Expression of bacterial adhesins after stress was assessed by immunoblot and flow-cytometric analysis. Bacteria-lipid binding was determined by thin-layer chromatography overlay assay.Results. Brief low-pH stress ( with or without acid adaptation) and bile-salt stress resulted in significantly increased EPEC-host cell adhesion. Erythromycin pretreatment eliminated the adhesion enhancement, suggesting that protein synthesis was required. Immunoblot and flow-cytometric analysis indicated little change in expression of known adhesins after either stress. However, we found increased surface expression of a heat-shock protein 70 (Hsp70) on acid-shocked EPEC, and pretreatment with anti-Hsp70 eliminated the adhesion enhancement after acid stress. Acid shock also correlated with increased binding to sulfogalactosylceramide, a putative receptor for other pathogens after stress.Conclusions. Acid/bile-salt stress of EPEC significantly enhances adhesion to host cells, and a novel adhesin-receptor pair may play a role in the adhesion.