FIG. 5.

Distinct effect of DSS application and E. coli Nissle 1917 treatment on MPO activity in wt, TLR-2 knockout, and TLR-4 knockout mice. In TLR-4 knockout mice, DSS application induced significantly less MPO activity in colonic tissue compared to wt or TLR-2 knockout mice. wt mice, but not TLR-2 knockout or TLR-4 knockout mice, treated rectally with 10⁷ E. coli Nissle 1917 showed a significant decrease in MPO activity compared to mice treated with 0.9% NaCl. Colitis was induced by DSS application in wt, TLR-2 knockout, and TLR-4 knockout mice. Mice were subsequently treated with an oral or rectal application of 10⁷ E. coli Nissle 1917 (100 μl) or 0.9% NaCl (100 μl) for 8 days. After sacrifice, the MPO activity was determined as described in Materials and Methods. Each bar represents mean ± the SEM value of 10 animals. *, P < 0.05 for differences in E. coli Nissle 1917-treated groups versus saline-treated animals.