Epithelial antimicrobial defence of the skin and intestine

Abstract

Mammalian intestine and skin interface with the external environment and are thus in contact with both pathogenic and commensal microorganisms. Antimicrobial proteins produced by epithelial cells are essential for defending against microbial challenges at these tissue sites. Mammalian antimicrobial proteins are members of a diverse array of protein families and kill microorganisms through various mechanisms, including enzymatic attack and membrane disruption. Several antimicrobial proteins also function as potent immune regulators that modulate downstream immune responses to microorganisms. The expression, secretion and activity of antimicrobial proteins are tightly controlled. Regulation is multifaceted, encompassing both transcriptional and post-translational mechanisms. Antimicrobial proteins function in vivo to limit pathogen colonization, to determine microbiota composition and to restrict microbiota access to host tissues. Dysregulation of antimicrobial protein function is associated with diseases of the intestine and skin. These include inflammatory bowel disease and skin disorders such as atopic dermatitis, rosacea and psoriasis.