Figure 3

The effect of DSS and DSS + l-clodronate treatment on the mouse colon. IF stainings show colon sections of mice euthanized at the 4th day of DSS-treatment, where ECM molecule agrin delineate ganglia with intact myenteric plexus barriers. F4/80+ macrophages are already infiltrated the mucosa, but not the muscularis at this timepoint (A,A′). Arrows indicate scattered MMs in early DSS colon (A′). Cell counting shows that a significantly increased number of mucosal macrophages (MucM) are present in DSS- (8th day) compared to 4th day DSS- (p = 0.037) and control conditions (p < 0.001), likewise between control- and 4th day DSS conditions (p = 0.017) (B,B′). Panels (C–C″) show morphology of control (C), DSS-vehicle-treated (C′) and DSS-clodronate-treated (C″) colon stained with IF using antibodies Hu (enteric neurons), agrin and F4/80. Arrowheads indicate MMs, arrows indicate intraganglionic macrophages within the agrin-labeled myenteric plexus barriers. Bar charts show the results of morphometry and cell counting in the same experimental setting (D–E′). There was no significant difference in mucosa thickness in any comparison (D). Colon submucosa was significantly thicker in DSS- (p < 0.001) and DSS-clodronate treated mice (p < 0.001) compared to control littermates. For the same parameter, there was a modest, but significant difference between DSS- and DSS-clodronate treated animals (p = 0.026) (D′). The muscularis was significantly thicker in DSS-vehicle-treated animals compared to DSS-clodronate-treated (p < 0.001) and control mice (p = 0.011). There was no significant difference between the control and DSS-clodronate-treated groups. MucM density was significantly increased in DSS-vehicle-treated animals compared to DSS-clodronate-treated (p = 0.026) and control mice (p < 0.001). There was trend towards increased MucM density in the DSS-clodronate group vs the control group, but it did not reach statistical significance (E). MM density of DSS-vehicle-treated animals was significantly increased compared to both control (p < 0.001) and DSS-clodronate-treated animals (p < 0.001), but showed no significant difference between the control and the DSS-clodronate-treated groups (E′). Metric data are shown as mean and corresponding standard deviation (SD). Statistical significance *p < 0.05; **p < 0.01, ***p < 0.001. ggl enteric ganglion, lm longitudinal layer of muscularis externa, cm circular layer of muscularis externa, muc mucosa, sm submucosa.