The human body is constantly being subjected to a barrage of chemical, physical, and biological insults from the gastrointestinal (GI) lumen. The body is protected by the so-called intestinal barrier.1
The epithelial barrier is highly selective and semipermeable. It is a complex, dense mucous layer composed of IgA, antimicrobial peptides, and junctional complexes, including tight junctions (TJs).
Intestinal epithelium safeguards the mucosal barrier immunity.2