Figure 7.

Ablation of Lgr5+ stem cells exacerbates IL-10-deficiency colitis but has only modest effects on 2,4,6-trinitrobenzene sulfonic acid (TNBS) colitis. A: experimental interventions performed on Lgr5::DTR-EGFP (Lgr5-DTR) and wild-type (WT) mice. Data shown are representative from three independent experiments, each involving five mixed-sex mice per group. Mice were injected weekly with an antibody against the IL-10 receptor (IL10R) or an isotype control antibody, beginning at 3-wk old. At 7-wk old, mice were injected with diphtheria toxin (DT) to ablate Lgr5+ stem cells, or PBS control. The clinical course was acutely monitored for 4 days. B: hematoxylin-eosin (H&E)-stained photomicrographs show epithelial hyperplasia and mucosal immune infiltration in anti-IL10R-treated animals. C: immuostaining for GFP marking Lgr5+ stem cells validates the persistence of Lgr5+ stem cells in the crypts of anti-IL10R-treated mice. However, injection of diphtheria toxin (DT) ablates the staining signal consistent with the DT-induced loss of Lgr5+ stem cells. D: body weight curve of mice with colitis (anti-IL10R) or in homeostasis (IgG) with or without DT treatment. Specifically, colitic mice with DT treatment (ablated Lgr5+ stem cells) exhibited a rapid loss of body weight. E: ablation of Lgr5+ cells increased the colonic thickness of mice with colitis. This is consistent with exacerbation of injury. Overall histological colitis score (F) was unchanged among the sample groups. No histological damage was found to be associated with Lgr5+ stem cell ablation in homeostasis. However, subcategory scoring (G) revealed a higher proximal-to-distal percentage of the mucosa involved in colitic mice with ablated Lgr5+ stem cells, which could be seen in histological images (H). I: summary schematic of the experimental interventions performed on Lgr5::DTR-EGFP (Lgr5-DTR) mice in the TNBS colitis model. Data shown are representative of two independent experiments, each involving the analysis of four mice per group. No significant differences in body weight (J), colonic thickness (K), or overall histological score (L) were observed to be associated with DT treatment of mice with TNBS colitis. Subcategory histological scoring (M) showed a higher index of crypt inflammation. Displayed is an example image (O) of the qualitatively increased mucosal infiltrate. Scale bars: 50 µm. Statistics: *P < 0.05; **P < 0.01; ***P < 0.001. Two-tailed t test. Error bars: means ± SE.