Fig. 2.

Gpa33^−/− mice are sensitised to impaired intestinal barrier function. (A) Mice were provided with 2% DSS in the drinking water ad libitum for 16 h following which TRITC-dextran was administered by gavage. Four hours later, the TRITC signal in the serum was quantitated as a measure of intestinal permeability. DSS-treated Gpa33^−/− but not WT mice exhibit an increase in serum TRITC-dextran, which is indicative of impaired intestinal barrier function. (B) Representative images of H&E-stained distal and mid colon sections from mice treated with 2% DSS in the drinking water for 16 h, illustrating morphological integrity of the epithelial layer after DSS treatment. The right-hand column provides higher magnifications of the boxed areas. (C) Representative histological images of mid colon from 10-week-old Gpa33^−/− and WT mice stained with alcian blue and Periodic acid-Schiff for neutral (magenta) and acidic (blue) mucins, respectively, in the presence and absence of DSS treatment. Scale bars: (B) 100 µm and (C) 50 µm. (D) Single-cell suspensions of colon LP were prepared and the numbers of DCs and macrophages were determined by FACS. The gating strategy for activated CD103⁺ DCs derived from viable, single, haematopoietic cells (Epcam⁻ CD45⁺) is shown. (E) Absolute cell numbers for populations within the whole colon LP were calculated using relative cell populations obtained by FACS and viable single-cell counts. Gpa33^−/− mice exhibit an increase in activated DCs within the colonic LP relative to WT controls, indicating elevated immunosurveillance. Populations represent: DCs (Epcam⁻ CD45⁺ CD11c⁺ F4/80⁻ MHC-II⁺), CD86⁺ activated DCs, gut resident CD103⁺ DCs and macrophages (Epcam⁻ CD45⁺ CD11c⁺ F4/80⁺). (F) Geometric mean for CD86 in DCs and CD130⁺ DC populations. Mean±s.e.m., (A) n=7-8, (E,F) n=6, *P<0.05.