Barrier epithelial cells lining the mucosal surfaces of the gastrointestinal and respiratory
tracts interface directly with the environment. As such, these tissues are continuously
challenged to maintain a healthy equilibrium between immunity and tolerance against
environmental toxins, food components, and microbes. An extracellular mucus barrier,
produced and secreted by the underlying epithelium plays a central role in this host defense
response. Several dedicated molecules with a unique tissue-specific expression in mucosal …