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Epithelial Cells Secrete Interleukin‐8 in Response to Adhesion and Invasion of Diffusely Adhering Escherichia coli Lacking Afa/Dr Genes
Author(s) -
Meraz Ismail Mustafa,
Arikawa Kentaro,
Ogasawara Jun,
Hase Atsushi,
Nishikawa Yoshikazu
Publication year - 2006
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/j.1348-0421.2006.tb03781.x
Subject(s) - biology , bacterial adhesin , microbiology and biotechnology , secretion , intracellular , escherichia coli , interleukin 8 , motility , cytokine , enteropathogenic escherichia coli , interleukin , bacteria , gene , immunology , genetics , biochemistry
Escherichia coli that sparsely adhere to human epithelial cells are known as diffusely adherent E. coli (DAEC), and the role of the Afa/Dr family of adhesins is now understood. Strains that do not possess Afa/Dr, however, comprise another group of DAEC, of which the pathogenicity remains unknown. The ability to induce interleukin‐8 (IL‐8) secretion from intestinal epithelial cells might be a feature of enterovirulent bacteria. We previously found that some Afa/Dr DAEC strains induce IL‐8 by stimulating epithelial cells with flagella. The present study examines whether non‐Afa/Dr DAEC can induce IL‐8 in epithelial cells (HEp‐2, INT407, and T84). Among 21 strains, 11 (52%; 11/21) induced as much IL‐8 as high inducer strains of Afa/Dr DAEC. Adhesion did not significantly differ between high and low inducers; therefore diffuse adhesion alone is probably insufficient to induce IL‐8. It was shown that IL‐8 induction and the number of intracellular bacteria directly correlated. Wortmannin, an inhibitor of the phosphatidylinositol‐3‐phosphate kinase, reduced both intracellular bacteria and IL‐8 secretion. Motile strains were significantly more prevalent among high (10/11) than low (4/10) inducers. However, 4 low invasive strains hardly induced IL‐8 despite their motility. In conclusion, some non‐Afa/Dr DAEC invoke the induction of high levels of inflammatory cytokines. Unlike Afa/Dr DAEC, however, non‐Afa/Dr strains may require invasion to cause strong induction. These non‐Afa/Dr high inducers can be enteropathogenic for the cytokine‐inducing properties.