Antimicrobial peptides in the oral environment: expression and function in health and disease

Abstract

The oral cavity is a unique environment in which antimicrobial peptides play a key role in maintaining health and may have future therapeutic applications. Present evidence suggests that alpha-defensins, beta-defensins, LL-37, histatin, and other antimicrobial peptides and proteins have distinct but overlapping roles in maintaining oral health and preventing bacterial, fungal, and viral adherence and infection. The expression of the inducible hBD-2 in normal oral epithelium, in contrast to other epithelia, and the apparent differential signaling in response to commensal and pathogenic organisms, provides new insights into innate immunity in this body site. Commensal bacteria are excellent inducers of hBD-2 in oral epithelial cells, suggesting that the commensal bacterial community acts in a manner to benefit the overall innate immune readiness of oral epithelia. This may have major significance for understanding host defense in the complex oral environment.

Fig. 1

Localized expression of antimicrobial peptides in gingiva. Diagrammatic view of a cross-section of the gingiva illustrating the oral aspect of the tissue, the gingival margin at the crest of the gum tissue, and the junctional epithelium attaching to the tooth surface. The sulcular epithelium is adjacent to the space (sulcus) between the tissue and the tooth. Neutrophils, containing α-defensins and LL-37, migrate through the junctional epithelium into the gingival sulcus. β-Defensins are expressed in the gingival epithelium. The tissue is bathed in saliva containing histatins, LL-37 and α- and β-defensins.