Figure 3

IL-8 secretion from INT 407 cells is not invasion dependent, but MAPK activation is required for host cells invasion by C. jejuni . (A) A C. jejuni ciaD mutant is deficient in maximal invasion of INT 407 cells. The C. jejuni ciaC mutant was included as an invasion deficient control. (B) IL-8 secretion does not require bacterial invasion. INT 407 cells were inoculated with various C. jejuni isolates, incubated for 24 hr, and IL-8 quantified using an IL-8 ELISA as described in Methods. The C. jejuni flgBC flagellar mutant (Cia secretion negative) and C. jejuni ciaC mutant (CiaC secretion negative and invasion deficient) were included as negative controls. (C) MAP kinase activation is required for C. jejuni invasion. Inhibitors to Erk 1/2 (PD98059) and p38 (SB 202190) were added to INT 407 cells for 30 min prior to the addition of a C. jejuni wild-type strain. (D) MAP kinase activation is required for IL-8 secretion. Inhibitors of Erk 1/2 and p38 were added to INT 407 cells for 30 min prior to inoculation with a C. jejuni wild-type strain. The values obtained from uninfected cells were subtracted from all other values. The asterisks indicate a significant reduction compared to the value obtained for the C. jejuni wild-type strain, according to one-way ANOVA followed by post-hoc Tukey’s analysis (P < 0.05). Error bars represent ± SEM of N = 12 samples from 3 independent experiments.