Page 703 - Veterinary Immunology, 10th Edition

enterocytes consists of firm mucus rich in defensins and lysozyme
VetBooks.ir and contains few bacteria. The looser mucus in the intestinal lumen

is composed primarily of mucins produced by intestinal goblet
cells. Many bacteria are embedded in this mucus, where it prevents

their washout. Its thickness and composition vary, but it tends to be
thickest where the microbiota is abundant. The enterocyte brush
border is also covered by a glycocalyx, a layer of acidic
polysaccharides and glycoproteins that binds to the apical surface

of the cells and serves as a protective barrier while still permitting
the absorption of nutrients.
Goblet cells are the source of intestinal mucus. Both the
inflammasome and autophagy pathways control the production of

this mucus. In the absence of inflammasomes, mucus production is
reduced and mice develop severe colonic inflammation. Autophagy
proteins also regulate mucus production. Upon consideration, this
should not come as a surprise to most people, especially

veterinarians. Mucus secretion increases greatly in response to
mucosal inflammation—it's called a “runny nose”!

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