Objective The attaching and effacing (A/E) pathogens enterohaemorrhagic Escherichia coli, enteropathogenic E coli and Citrobacter rodentium colonise intestinal tracts, attach to enterocytes, collapse infected cell microvilli and alter numerous host cell processes during infection. Enterocyte alterations result in numerous small molecules being released from host cells that likely contribute to diarrhoeal phenotypes observed during these infections. One possible route for small molecules to be released from intestinal cells may be through functional gap junction hemichannels. Here we examine the involvement of these hemichannels during the diarrhoeal disease caused by A/E pathogens in vivo.
Design Mice were infected with the diarrhoea-causing murine A/E pathogen C rodentium for 7 days. Connexin43 (Cx43) protein levels and immunolocalisation in the colon were initially used to determine alterations during A/E bacterial infections in vivo. Connexin mimetic peptides and connexin permeable tracer molecules were used to gage the presence and function of unpaired connexin hemichannels. The role of Cx43 in diarrhoea generation was assessed by comparing infections of wild-type mice to Cx43 mutant mice and determining the water abundance in the colonic luminal material.
Results We demonstrate that Cx43 protein levels are increased in colonocytes during in vivo A/E bacterial infections, resulting in functionally open connexon hemichannels in apical membranes of infected cells. Moreover, infected Cx43 +/− mice do not suffer from diarrhoeal disease.
Conclusions This study provides the first evidence that functional connexon hemichannels can occur in the intestine and are a novel molecular mechanism of water release during infectious diarrhoea.
- attaching and effacing pathogens
- gap junction
- bacterial infection
- cell biology
- enteric infections
- infectious diarrhoea
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Supplementary methods and figures are published online only at http://gut.bmj.com/content/Vol59/issue2
JAG and AE-JL contributed equally to this paper.
Funding AEJL is the holder of a CIHR Frederick Banting and Charles Best Canada Graduate Scholarship Doctoral Award. JAG is a CIHR New Investigator. BBF is a Howard Hughes International Research Scholar, a CIHR Distinguished Investigator and the UBC Peter Wall Distinguished Professor. CCN is a Canada Research Chair. This study was funded through operating grants from the Canadian Institutes of Health Research, Natural Sciences and Engineering Research Council. Other funders: Howard Hughes Medical Institute.
Competing interests None.
Ethics approval The animals were maintained according to the Canadian Council on Animal Care guidelines for the care and use of laboratory mice at the University of British Columbia.
Provenance and peer review Not commissioned; externally peer reviewed.