Regulation of expression of beta-defensins: endogenous enteric peptide antibiotics.

Evidence for the central role that intestinal beta-defensins play in maintaining gut health continues to accumulate within the literature. Two epithelially-derived enteric beta-defensins, hBD1 and hBD2, have been identified thus far and the following chapter reviews our current understanding of how the expression and secretion of these endogenous antimicrobial, chemotactic and adjuvant peptides is regulated within the context of the most microbe-rich of mucosal environments, the gastrointestinal tract. The agonists and microbial moieties identified as being responsible for the direct receptor-mediated induction of enteric epithelial beta-defensins, the signaling and nuclear events that are triggered as a consequence and which drive defensin gene transcription, the potential antimicrobial and immunomodulatory consequences of beta-defensin release within the luminal and mucosal aspects of the alimentary tract thereafter and the validity of animal models for the study of these key immune effector molecules in vivo are discussed. These significant and recent discoveries have provided much in the way of momentum for the pace with which this exciting and dynamic area of mucosal immunology research continues to move forward.