Expression of β-defensins in gingival health and in periodontal disease

BACKGROUND: Human β-defensins (HBDs) are epithelial-derived antimicrobial peptides. The expression of three HBDs (HBD-1, HBD-2, and HBD-3) has been reported in oral mucosa, gingiva, and salivary glands. However, their role in protection against oral infections is not well understood. This study examined the expression of HBD-1, HBD-2, and HBD-3 mRNAs in gingival health and periodontal disease. METHODS: Gingival tissue discarded from periodontal procedures was obtained from 20 periodontally healthy and 29 periodontally diseased sites. Total RNA was isolated, and expression of β-defensins was analyzed by both 35-cycle and semiquantitative (25-cycle) reverse transcription-polymerase chain reaction (RT-PCR). The level of expression was assigned ordinal scores of no expression, low expression, or high expression. mRNA expression was compared between healthy and diseased groups using exact tests of homogeneity and Cochran-Mantel-Haenszel tests; associations among the variables were assessed using exact tests and Kendall's tau-b statistic. RESULTS: All 49 samples demonstrated basal mRNA expression of HBD-1, HBD-2, and HBD-3. Significantly higher levels of HBD-3 (P = 0.012) expression were found in the healthy tissues as compared to the diseased ones. There was also a suggestion of higher expression of HBD-2 in the healthy tissues (P = 0.12). Levels of HBD-1, HBD-2, and HBD-3 mRNA expression were correlated with one another (P < 0.001). CONCLUSIONS: High levels of HBD-3 mRNA expression in healthy tissues suggest a potentially important protective role for defensins in the host immune response to infection by periodontal pathogens.