Fig. 2

Diet rich in microbiota-accessible carbohydrate prevented degradation of colonic mucus barrier, reduced tight junction expression, and endotoxemia in diet-induced obese mice. a Alcian blue-stained colonic sections showing the mucus layer (arrows). Opposing black arrows with shafts delineate the mucus layer that was measured. Scale bar 50 μm. b The quantification of colonic mucus layer was statistically analyzed (per section/2 sections per animal, n = 5). c Immunofluorescence images of colonic sections stained with a-MUC2 (green) and DAPI (blue). Opposing white arrows with shafts delineate the mucus layer. Inset (HF-FD group) shows a higher magnification of bacteria-sized, DAPI-stained particles in closer proximity to host epithelium and even crossing this barrier. Scale bar 50 μm, inset 10 μm. d FISH analysis of sections of the colon using the general bacterial probe EUB338-Alexa Fluor 488 (green) and nuclear staining DAPI (blue). Arrows indicate the distance between bacteria and epithelium. Scale bar 10 μm. e Quantitation of colonic Reg3γ by RT-PCR (n = 6). e Protein expression levels of occludin (f) and ZO-1 (g) in the colon (n = 5). h Fecal albumin concentrations (n = 8). i Serum endotoxin level (n = 10). Values are mean ± SEM. ^*p < 0.05 vs. Control (Con). ^#p < 0.05 vs. high-fat and fiber-deficient (HF-FD)