Campylobacter jejuni cytolethal distending toxin mediates release of interleukin-8 from intestinal epithelial cells

Live cells of Campylobacter jejuni and Campylobacter coli can induce release of interleukin-8 (IL-8) from INT407 cells. Additionally, membrane fractions of C. jejuni 81-176, but not membrane fractions of C, coli strains, can also induce release of IL-8, Membrane preparations from 81-176 mutants defective in any of the three membrane-associated protein subunits of cytolethal distending toxin (CDT) were unable to induce IL-8, The presence of the three cdf genes on a shuttle plasmid in trans restored both CDT activity and the ability to release IL-8 to membrane fractions. However, CDT mutations did not affect the ability of 81-176 to induce IL-8 during adherence to or invasion of INT407 cells, When C. jejuni cdt genes were transferred on a shuttle plasmid into a C, coli strain lacking CDT, membrane preparations became positive in both CDT and IL-8 assays. Growth of C,jejuni in physiological levels of sodium deoxycholate released all three CDT proteins, as well as CDT activity and IL-8 activity, from membranes into supernatants. Antibodies against recombinant forms of each of the three CDT subunit proteins neutralized both CDT activity and the activity responsible far IL-8 release, The data suggest that C. jejuni can induce IL-8 release from INT407 cells by two independent mechanisms, one of which requires adherence and/or invasion and the second of which requires CDT.