Figure 1.

Schematic of the intestinal epithelial barrier. The lining of epithelial cells forms a barrier between the host body and the gut’s lumen with commensal bacteria. The functional barrier cells are held together by many tight junction proteins that hinder the entry of bacteria. The mucosal layer acts as a first-line defense that prevents the contact of gut microbiome with intestinal epithelial cells. The role of immune cells against infection further maintains the hemostasis of the intestinal epithelial barrier.