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CAMPYLOBACTER JEJUNI INFECTION INDUCES A TIME DEPENDENT IMPAIRMENT IN THE INTEGRITY OF POLARIZED EPITHELIAL CELLS

E Wine, PM Sherman
Research Institute, Hospital for Sick Children, University of Toronto, Toronto, Ontario

BACKGROUND: The pathogenesis of chronic inflammatory bowel diseases (IBD) involves the interaction of host genetic susceptibility, luminal bacteria, and an aberrant immune response. Increased intestinal permeability may also contribute to IBD pathogenesis; whether this is genetically determined or the result of environmental factors, however, is not known. Enteric bacterial pathogens, including the most common bacterial cause of enterocolitis in humans - Campylobacter jejuni, are implicated as contributors to IBD.
AIM: The purpose of this study was to define the effects of C. jejuni infection on mucosal permeability in model polarized epithelia.
METHODS: MDCK1 cells were grown in Transwells and infected with 3 prototype C. jejuni strains (TGH 9011, NCTC 11168, ATCC 81-176) at a multiplicity of infection of 100:1 for up to 48 hours at 37°C. Transepithelial electric resistance (TER) was measured at 0, 18, 24, and 48 hours after infection. Dextran, a macromolecular (10-kDa) permeability probe, was apically inserted and sampled 5 hours later from the basolateral compartment. Transmission electron microscopy (TEM) and confocal microscopy were used as complementary methods to assess epithelial monolayer integrity.
RESULTS: In contrast to other enteric bacterial pathogens, such as enterohemorrhagic Escherichia coli O157:H7, only a mild reduction in TER was demonstrated after 18 hours of C. jejuni infection. However, a time dependent reduction in TER was observed at 24 and 48 hours for C. jejuni strain 9011 (66% of control, N=6, p<0.001). Prolonged infection caused a 1.5-, 3.0- and 1.7-fold increase in permeability to dextran, relative to uninfected controls, with strains 9011, 11168 and 81-176 infections, respectively (N=4-5, p>0.05), whereas E. coli O157:H7 infection increased permeability by 78-fold (p<0.0001). TEM demonstrated areas of tight junction separation and loss of polarity in C. jejuni-infected monolayers. The effects of C. jejuni were also demonstrated by an abnormal (punctate and interrupted) distribution of the tight junction protein ZO-1 using laser confocal imaging.
CONCLUSIONS: C. jejuni infections result in epithelial barrier disruption. C. jejuni -induced changes in monolayer integrity were demonstrated by a reduction in TER, destruction of apical junctional complexes, and a redistribution of tight junction protein. These findings provide insight regarding interactions between an enteric bacterial pathogen linked to IBD and the host epithelial cell barrier.

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