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 α-defensins, β-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.
The oral environmentThe oral cavity is a unique environment. Oral mucosa is a critical protective interface between external and internal environments and must serve as a barrier to the myriad microbial species present in this warm, moist environment. The oral cavity is the only area of the body in which hard tissues break through the epithelial surface. The periodontal epithelium surrounding the tooth is specialized to form an attachment and seal around each tooth. This unique function imparts special challenges to the tissue and leads to certain vulnerabilities associated with periodontal disease, especially in view of the continual exposure to the bacterial biofilm (dental plaque) that forms on the tooth surface at the junction of the soft tissue. Thus, this anatomical region is one where there is a significant risk of bacterially induced infection and inflammation.Antimicrobial peptides are important contributors to maintaining the balance between health and disease in this complex environment. These include several salivary antimicrobial peptides, the β-defensins expressed in the epithelium, the α-defensins expressed in neutrophils, and the cathelicidin, LL-37, expressed in both epithelium and neutrophils. These peptides are part of the host innate immune response in this environment. Epithelia, polymorphonuclear leukocytes (neutrophils), and saliva all contribute to the maintaining the health of the oral cavity in overlapping but independent ways. This review will focus on the human oral cavity and include 1) the expression and function of antimicrobial peptides in the oral cavity in the context of innate immune responses, 2) regulation of β-defensins which has led to advances in our understanding of oral epithelial innate immunity, and 3) functional efficacy against oral microbes when it is known.
Epithelial antimicrobial peptidesHistorically, the oral epithelium has been considered mainly as a passive covering that becomes damaged and ulcerated in disease. This view has changed dramatically and the epithelial compartment is now seen as providing both...