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Increased mucosa-associated diffusely adherent E coli in Crohn's and colon cancer: possible role in pathogenesis [Abstract]

Friswell, M. K., Roberts, C. L., Winstanley, C., Marchesi, Julian Roberto, Rhodes, J. M. and Campbell, B. J. 2010. Increased mucosa-associated diffusely adherent E coli in Crohn's and colon cancer: possible role in pathogenesis [Abstract]. Gut 59 (S1) , A110. 10.1136/gut.2009.208983h

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Introduction: Mucosa-associated adherent invasive Escherichia coli (AIEC) are found in colorectal cancer (CRC) and Crohn's disease (IBD).1 They invade intestinal epithelial cells, replicate in macrophages and interact with epithelial cells in vitro to promote proinflammatory cytokine release and NFkB activation.2 The adherent-invasive phenotype strongly correlates with the ability to agglutinate red blood cells (RBCs). We suspect that mucosa-associated E coli may also play a role in CRC pathogenesis by activation of key cellular pathways. Our aim here was to identify and characterise adherence mechanisms for our colonic AIEC isolates. Methods: A fosmid library was constructed containing 30–60 kb DNA fragments from E coli HM358, a CRC mucosa-associated isolate. Clones were screened for the ability to haemagglutinate RBCs. Agglutinating positive (HA+) clones were further assessed for their ability to adhere to epithelial Hep2 cells, to replicate within macrophages and for their ability to translocate across M-cells. They were then subjected to 454 DNA sequencing. Subsequently, 280 E coli isolates from IBD, CRC and healthy control patients were assessed for the presence of a gene cluster identified from sequence analysis. Results: Of the 964 fosmid clones constructed, 8 displayed a strong HA+ phenotype. Sequence data demonstrated all possessed a diffuse adherence gene cluster (afaA-E). HA+ positive clones were diffusely adherent to Hep2 cells and showed marked ability to replicate within macrophages when compared to HA- clones (p<0.01; ANOVA). In vitro data also suggest that the presence of afa/dr in E coli promotes translocation across M cells, a key portal of mucosal entry. E coli containing afa/dr were more commonly isolated from IBD and CRC patients (57% afa positive) than from healthy controls (28% afa positive, p<0.001 {chi}2 test). Conclusion: Afa/dr E coli are more commonly isolated from IBD and CRC patients than from healthy controls and have properties, including epithelial invasion and replication in macrophages, that overlap with AIEC. Other studies have shown that adherent afa/dr E coli play a key role in the upregulation of angiogenic vascular endothelial growth factor (VEGF) in the intestinal epithelium3 and they may thus have a role in pathogenesis of CRC as well as IBD.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Systems Immunity Research Institute (SIURI)
Additional Information: British Society of Gastroenterology Annual General Meeting 2010
Publisher: BMJ Publishing Group Ltd
ISSN: 0017-5749
Last Modified: 04 Jun 2017 02:05

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