Figure 7. C. rodentium infection results in increased mucin secretion during infection.

A. Representative PAS/Haematoxylin staining of Carnoy's fixed rectal sections from uninfected (left panel) and C. rodentium-infected mice (right panel). Arrow points to luminal mucus. Original magnification  = 100×. Scale bar  = 100 µm. B. Total counts per minute (CPM) of [³H]-glucosamine labeled glycoproteins found in colorectal secretions 3.5 hrs post-injection from uninfected and infected (6 DPI) WT mice. Results are representative of 2 independent infections containing 5 mice per group. C. Plot of liquid scintillation counts of fractions containing [³H] activity after total secretions were subjected to gel filtration on a Sepharose 4B chromatography column. This graph is representative of 2 independent infections with 5 mice per group. D. Graph of total CPMs of void volumes of S4B-fractionated mucins as described in D. Data represents the mean of the average of 2 independent experiments, each with 5 mice per group. Error bars  =  SEM. E. Combined epifluorescent staining for mucus using the lectin UEA-1 (red), and C. rodentium LPS (green), and cellular DNA (blue) using DAPI as a counterstain in heavily infected (6 DPI) regions of the colorectal mucosa from WT and Muc2^−/− mice, as indicated. Individual C. rodentium (arrowhead, inset “a”) can be seen in mucus overlying a single layer of C. rodentium on the mucosal surface of a WT mouse. A C. rodentium microcolony (white arrow) can be seen in vicinity of a Muc2/mucus-deficient environment as indicated by the absence of mucus in the crypt lumens in Muc2^−/− mice compared to WT mice (yellow arrow). Original magnification  = 200×. Scale bar  = 50 µm.