Figure 4.

Toll-like receptor 3 (TLR3) signals via resident radio-resistant tissue cells. (A) Lethally irradiated host mice were recovered 6–7 h after radiation with a total of 1.2 x 10⁷ bone marrow (BM) cells. Four chimeric groups were generated (wt x TLR3^-/-BM, TLR3^-/- x wt^BM, TLR3^-/- x TLR3^-/-BM, and wt x wt^BM). Six weeks later, all four groups underwent intestinal manipulation (IM). (B) MPO⁺ leukocyte numbers were identified by Hanker-Yates (HY) reaction in mucosal-free muscularis whole mounts 24 h after surgery (IM24h). TLR3^-/- that received wt bone marrow showed lower leukocyte infiltration compared to wt mice that received TLR3^-/- bone marrow. (C) Gastrointestinal (GI) transit time was determined by distribution of a fluorescent meal along the GI tract within a defined time period. Data were calculated as geometric center of the fluorescence marker distribution. Geometric center (GC) values reciprocally correlate to the motility. St, stomach; C, cecum; Col, colon. Experiments were performed two times reaching an overall size of n = 6 animals per group. Means + SEM were generated from the overall numbers of each group. Samples were analyzed by two-way analysis of variance with Tukey post hoc test and the results are displayed as means ± SEM. *p ≤ 0.05 versus indicated groups.