Fig. 5.

Mice treated with imipenem-cilastatin in the setting of GVHD result in the loss of the colonic mucus layer, and impaired intestinal barrier function. (A to C) Colon tissues from mouse recipients were fixed by water-free Methanol-Carnoy's fixative on day 21, stained with Periodic acid-Schiff (PAS) stain and visualized by light microscopy. Orange triangles in A indicate the location of the inner mucus layer. Quantification of mucus layer thickness is shown in B. Number of goblet cells are shown in C. Data are representative of two independent experiments. Values represent mean ± SEM (n = 10). **, P < 0.01 by Mann-Whitney U test. (D) Immunostaining for Muc2 (green) of the colon sections with general bacterial 16S rRNA gene FISH probe EUB338 (red) counterstained with Hoechst (blue). Data are representative of two independent experiments (n = 10). Orange arrowheads indicate inner mucus layer; red arrowheads indicate bacteria penetrating beyond the mucus layer and colonic epithelium. The white scale bar indicates 10 μm. (E) Allo-HSCT recipients of bone marrow and T cells treated with aztreonam or imipenen-cilastatin were challenged with oral gavage of FITC-dextran on day 15 post-transplant. The graph shows plasma FITC-dextran concentrations. Data are representative of two independent experiments. Values represent mean ± SEM (n = 6–8). *, P < 0.05 by Mann-Whitney U test.