Creation of a large deletion mutant of Campylobacter jejuni reveals that the lipooligosaccharide gene cluster is not required for viability.

Deletion of the lipooligosaccharide biosynthesis region (Cj1132c to Cj1152c) from the genome of Campylobacter jejuni NCTC11168 shows that the core is not required for viability. The mutant was attenuated for growth and has increased sensitivity to antibiotics and detergents. Natural transformation and invasion of cultured host cells was abolished.

Campylobacter jejuni-infected human epithelial cell lines vary in their ability to secrete interleukin-8 compared to in vitro-infected primary human intestinal tissue.

Campylobacter jejuni causes symptoms of acute inflammatory diarrhoea in man. C. jejuni interaction with epithelial cells elicits interleukin-8 (IL-8) production, and IL-8 recruits neutrophils to sites of infection. Cell culture models of bacterial interaction with epithelium are useful to define bacteria-host interaction and are used because it is thought they mimic the same bacteria-host cell interaction in the natural disease. This study looks at the ability of C. jejuni strains to elicit IL-8 production from a variety of cell lines previously used for investigating the interaction of C. jejuni with host cells. A spectrum of IL-8 responses was observed, with minimal IL-8 elicited from Caco-2 cells and more marked responses elicited from HeLa and T84 cells. These in vitro-infected cell line responses were compared to IL-8 production from in vitro C. jejuni-infected human colonic and ileal tissue. The in vitro-infected tissue elicited the highest IL-8 responses and the cytokine was manifested earlier compared to the infected cell lines.

Campylobacter jejuni inhibits the absorptive transport functions of Caco-2 cells and disrupts cellular tight junctions.

Caco-2 cells are models of absorptive enterocytes. The net transport of fluid from apical to basolateral surfaces results in 'domes' forming in differentiated monolayers. Here, the effect of Campylobacter jejuni on this process has been examined. C. jejuni caused no changes in short-circuit current upon infection of Caco-2 cell monolayers in Ussing chambers. Thus, no active secretory events could be demonstrated using this model. It was therefore hypothesized that C. jejuni could inhibit the absorptive function of enterocytes and that this may contribute to diarrhoeal disease. C. jejuni infection of fluid-transporting ('doming') Caco-2 cells resulted in a significant reduction in dome number, which correlated with a decrease in tight junction integrity in infected monolayers, when measured as transepithelial electrical resistance. Defined mutants of C. jejuni also reduced dome numbers in infected monolayers. C. jejuni also altered the distribution of the tight junction protein occludin within cell monolayers. The addition to monolayers of extracellular gentamicin prevented these changes, indicating the contribution of extracellular bacteria to this process. Thus, tight junction integrity is required for fluid transport in Caco-2 cell monolayers as leaky tight junctions cannot maintain support of transported fluid at the basolateral surface of infected cell monolayers. Inhibition of absorptive cell function, changes in epithelial resistance and rearrangement of tight junctional proteins such as occludin represent a potential diarrhoeal mechanism of C. jejuni.

Campylobacter jejuni activates mitogen-activated protein kinases in Caco-2 cell monolayers and in vitro infected primary human colonic tissue.

The mitogen-activated protein kinases (MAPKs) play a central role in many host signalling pathways. These signalling proteins are known to be involved in host responses against invasive bacteria including generation of chemotactic and inflammatory cytokines. It was hypothesized that Campylobacter jejuni may activate MAPKs, as intestinal infection may induce a clinical and pathological picture of acute colonic inflammation. Infection of Caco-2 cell monolayers (human colonic epithelial cell line) and human colonic tissue with C. jejuni in vitro demonstrated increased MAPK activity for ERK 1/2 (p44/42 MAPK), JNK and p38 MAPKs. Kinase activity and phosphorylated forms were increased in infected Caco-2 cells and human colonic explants, suggesting that these pathways are important in inflammatory responses induced by C. jejuni in man.