Figure 3.

Maintaining the ‘fence’. Balancing epithelial barrier health via cross-talk between epithelial cells and the luminal microorganisms, and the cells of the immune system, especially intraepithelial lymphocytes (IELs), themselves maintained via dietary derived aryl hydrocarbon receptor (AhR) ligands such as indole-3-carbinol (I3C). The IELs maintain the epithelial barrier via release of growth factors and support in the activation of antimicrobial peptides. Upon barrier breakthrough, IELs are directly involved in the cytolytic immune response, removing infected cells, and orchestrating subsequent adaptive immunity as well as the barrier repair response.