HOME
Return to Table of Contents
082 THE EFFECTS OF ATTACHING AND EFFACING PATHOGENS ON INTERCELLULAR JUNCTIONS JA Guttman1, AE Lin1, P Kazemi1, FN Samji1, ME Wickham1, Y Li1, W Deng1, AW Vogl2, BB Finlay1 Tight junctions and desmosomes are intercellular junctions that are responsible for maintaining the epithelial barrier and conferring strength to epithelia. It has been well established that tight junctions are extensively modified during in vitro A/E bacterial infections, however their effects during in vivo infections have not been described. Additionally, the role of A/E pathogen infections on desmosomes has been ignored. Recently a natural murine A/E pathogen, Citrobacter rodentium, has proven useful in assessing the effects of A/E bacteria in vivo. To examine the role of these junctions during infection we tested two hypotheses: 1) that tight junctions are altered during in vivo A/E infections and 2) that desmosomes also are altered during infection.
1Michael Smith Laboratories; 2Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia
In vivo experiments consisted of infecting C57/BL6 mice with C. rodentium for 7, 14 and 21 days. The human A/E pathogen enteropathogenic Escherichia coli (EPEC) was used on Caco-2 and MDCK cells for in vitro infections. Immunolocalization of tight junction and desmosomal proteins as well as electron microscopic analysis of the junctions was performed. Tight junction functional experiments included using biotin tracers to analyze the barrier function of the epithelium.
Here we demonstrate that tight junction alterations are dependent on the intimate interaction of C. rodentium with colonocytes in vivo. The distribution of the tight junction proteins, claudins-1, -3 and -5, junction morphology and function are extensively altered during active infection and are unaffected when the bacteria are cleared from the animals. Surprisingly, desmosome transmembrane and cytoplasmic proteins as well as desmosome morphology are unaltered during A/E infection in vitro or in vivo.
We conclude that tight junction disruption in vivo appears dependent only on the direct intimate attachment of A/E bacteria to the cells and that desmosomes are not targeted by A/E pathogens.