<i>C. jejuni</i> induces acute enterocolitis in gnotobiotic IL-10^−/− mice.

<p>Gnotobiotic IL-10^−/− mice were generated by antibiotic treatment and orally infected either with <i>C. jejuni</i> B2 (solid circles; black bar) or a commensal <i>E. coli</i> strain (crossed circles) derived from the commensal gut microbiota of conventional colonized wildtype mice as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040761#s4" target="_blank">Methods</a>. Uninfected gnotobiotic IL-10^−/− mice served as negative controls (open circles). (<b>A</b>) Relative rate of blood-positive stool samples of infected IL-10^−/− and uninfected control mice were determined by haemoccult test at day 7 p.i. (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040761#s4" target="_blank">Methods</a>). Numbers of animals with haemcoocult positive stool samples out of the total number of analyzed animals are given in parentheses (n.d., not detectable). (<b>B</b>) Absolute colon lengths and (<b>C</b>) histopathological changes applying a standardized histopathological score in HE-stained colonic paraffin sections were determined at day 7 p.i., illustrated by (<b>D</b>) representative photomicrographs out of three independent experiments (100x magnification, scale bar 100 µm) derived from naïve (left), <i>E. coli</i>- (middle) and <i>C. jejuni</i> B2- (right) infected animals. Solid arrows indicate mucosal, dotted arrows submucosal infiltrates, black arrow heads ulcerations, white arrow heads loss of goblet cells, and gray arrow heads mucosal bleeding. Numbers of analyzed animals are given in parentheses. Medians (black bars) and significance levels (<i>P</i>-values) determined by Mann-Whitney-U test are indicated. Data shown were pooled from at least three independent experiments.