In contrast to colonic IFN-γ release, caecal IFN-γ was maximal at day 7 (Fig. 1). No significant changes in cytokine production were

noted in small intestinal tissues (data not shown). The results shown are derived from experiments with 129/SvEv mice; however, results indistinguishable from these were also produced with Swiss Webster mice. The imbalance in intestinal learn more cytokine release with a maximal production of proinflammatory cytokines prior to production of anti-inflammatory cytokines was associated subsequently with a transient intestinal histopathological injury at day 7 post-faecal slurry exposure (Fig. 2a). The increase in intestinal injury scores was seen in both colonic and caecal tissues and involved mainly an influx in lamina propria mononuclear cells (Fig. 2b). However, not all mice developed colonic or caecal injury; the injury score among individual mice ranged from 1 to 8 in colon and from 1 to 7 in the caecum. EGFR inhibitor Higher scores were found primarily among the Swiss Webster

mice, whereas 129/SvEv mice scored generally lower. However, even those mice that were found to be microscopic disease-limited (i.e. histopathological injury score of 1 at day 7) demonstrated increased proinflammatory mucosal cytokine production. Colonic and caecal injury had subsided in most mice by day 14 (Fig. 2) and returned to base levels by day 28 (data not shown). Colonic epithelial permeability was not altered significantly in these mice when tested at days 3, 7 and 14 post-faecal slurry exposure. In fact, we observed a slight reduction in mannitol flux in colonic tissue when subjected to Ussing chamber analysis (Fig. 3). Thus, despite the temporary cytokine imbalance and brief inflammatory response in the large bowel, the intestinal epithelial barrier function appeared to be intact. To investigate systemic immune responses to ingestion of faecal slurry in these

axenic mice we assessed cytokine release in unseparated splenocytes stimulated with faecal lysates derived from specific pathogen-free (SPF)-raised mice. Maximal release of IFN-γ, IL-17 and IL-10 was measured at day 7 post-bacterial treatments (Fig. 4a, shaded bars). No increase in either TNF-α or IL-4 production GNA12 was noted in any of these antigen-stimulated spleen cell cultures. As expected, cytokine release following spleen cell stimulation with lysates from axenic mice that are devoid of bacterial components remained at baseline level (Fig. 4a, solid bars). Consistent with these results from stimulation with faecal lysates, we observed a similar increase in production of IFN-γ and IL-10 at day 7 in cultures stimulated with sonicates derived from pure cultures of three endogenous bacterial strains: Bacteroides vulgatus, Enterobacter cloacae and Lactobacillus reuteri (Fig. 4b).