Table 1.

Different physical and anatomical layers contributing to the intestinal barrier.

Microbial barrier (gut microbiota). Gut mucus, accumulating at the interface between the intestinal lumen and the brush border of enterocytes. Functional barrier, which is interplay between gastrointestinal motility and gastric acid, and biliary and pancreatic secretions. Epithelial barrier and tight junctions (enterocytes). Immunological barrier which is the combination of the immune-competent cells and their products. Gut–vascular interface. Liver barrier which represents the hepatic filter.

Adapted from Portincasa et al. [5].