Fig. 5.

Ileal pro-inflammatory immune responses in recolonized gnotobiotic mice following ileitis induction. Gnotobiotic mice generated by quintuple antibiotic treatment were perorally recolonized with E. coli Nissle 1917 (EcN), E. coli K12 (EcK12) or a commensal E. coli (EcCo) strain as described in Materials and methods. Four days thereafter, E. coli recolonized mice (grey circles) were perorally infected with 100 cysts of Toxoplasma gondii in order to induce acute ileitis. With conventional microbiota recolonized (SPF; black circles) and gnotobiotic (GB; white circles) animals served as positive and negative controls, respectively. The average number of cells positive for (a) CD3 (T Lymphocytes), (b) caspase-3 (Casp3, Apoptotic Cells) per animal were determined microscopically (HPF, 400× magnification) in immunostained ileum sections of mice at day 7 post ileitis induction. Numbers of analyzed animals are given in parentheses. Mean values and significance levels as determined by the Student’s t-test are indicated. Data are pooled from three independent experiments.