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Infect. Immun., 04 1997, 1414-1421, Vol 65, No. 4
BA McCormick, A Nusrat, CA Parkos, L D'Andrea, PM Hofman, D Carnes, TW Liang and JL Madara
Idiopathic intestinal disease states characterized by active inflammation
associated with transepithelial migration of neutrophils may,
paradoxically, be associated with an increased risk of infection by enteric
pathogens. Although the specific ligands with which various intestinal
pathogens associate remain largely unknown, it is thought that many reside
on the basolateral membrane. For example, beta1 integrin, a basolateral
membrane protein, mediates the specific interaction between epithelial
cells and the inv gene product (invasin) on the surface of Yersinia
pseudotuberculosis. Our observations indicate that neutrophil migration
across model T84 cell intestinal epithelia produced transient separation of
epithelial cells at sites of neutrophil migration, resulting in
microdiscontinuities that remained unsealed for several hours. We
hypothesized that such sites of microdiscontinuities would yield a
potential route for luminal pathogens to gain access to basolateral ligands
and, thus, provide a window of risk for enteric infection. The surface
biotinylation and fluorescence localization studies reported here revealed
that, as in natural intestinal epithelia, beta1 integrin was strictly
polarized to the basolateral membrane in confluent T84 monolayers. However,
the transient microdiscontinuities resulting from neutrophil migration
permitted access to beta1 integrin from the apical reservoir. Coincident
with such basolateral exposure of beta1 integrin, monolayers became
susceptible to invasion by Y. pseudotuberculosis. Fluorescence localization
indicated that Y. pseudotuberculosis selectively associated with monolayers
at sites where small discontinuities resulting from neutrophil
transmigration were found. An increased risk for Y. pseudotuberculosis
infection was specifically related to exposure of beta1 integrin (normally
concealed by tight junctions) to the apical compartment, as Y.
pseudotuberculosis cells lacking the inv gene were unable to invade
following neutrophil transepithelial migration. Following closure of the
microdiscontinuities associated with neutrophil migration, a small pool of
beta1 integrin remained apically localized, presumably due to incomplete
repolarization. However, this small apical pool of beta1 integrin was
insufficient to support a detectable increased risk of Yersinia infection.
Together, these observations indicate that by transiently perturbing
monolayer continuity, neutrophil transepithelial migration is associated
with a window of risk in which luminal pathogens can access basolateral
ligands such as beta1 integrin.
Copyright © 1997, American Society for Microbiology
Unmasking of intestinal epithelial lateral membrane beta1 integrin consequent to transepithelial neutrophil migration in vitro facilitates inv-mediated invasion by Yersinia pseudotuberculosis
Brigham and Women's Hospital, Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.
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