Figure 10.

Loss of epithelial Smad4 alters the immune microenvironment. (A–C) Sections from colons of Smad4+ controls (Smad4^fl/fl) or Smad4^ΔLrig1 mice were immunolabeled for F4/80 as a marker of macrophages. (A and B) Representative images of F4/80 staining (green) and nuclear counterstain (blue) in (A) control or (B) Smad4^ΔLrig1 colons. (C) Quantification of F4/80+ cells in each condition. (D–F) Sections from colons of Smad4+ controls (Smad4^fl/fl) or Smad4^ΔLrig1 mice were immunolabeled for myeloperoxidase (MPO) as a marker for neutrophils. (D and E) Representative images of MPO staining (brown) and nuclear counterstain (blue) in comparable regions of distal colon from (D) control or (E) Smad4^ΔLrig1 mice. (F) Quantification of MPO+ cells surrounding distal-most 100 crypts in each condition. (G–L) MPO immunolabeling in Smad4+ tumors from AOM/DSS-treated mice and in Smad4- tumors from Smad4^ΔLrig1 DSS-treated mice. Regions shown represent outer edges, central tumor regions, and regions of submucosal invasion, as indicated. Arrows indicate MPO+ cells at the tumor periphery. For each group, n = 5 or 6. *P < .05; ***P < .001 (2-tailed t tests). Scale bars: 100 μm. DAPI, 4′,6-diamidino-2-phenylindole.