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.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1086/462422 | DOI Listing |
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!