The guardians of the periodontium - sequential and differential expression of antimicrobial peptides during gingival inflammation. Results from in vivo and in vitro studies

Aim: To evaluate the sequential and differential expression of a variety of antimicrobial peptides (AMPs) during the development of an experimentally induced gingivitis in humans. Material and methods: In twenty healthy volunteers, gingival inflammation was induced by abstention from oral hygiene at 6 teeth. Bleeding on probing (BOP) and plaque index (PI) were assessed, and gingival biopsies and gingival crevicular fluid (GCF) were collected at 8 different time points (t0-t35). Gingival epithelial cells (GECs) were stimulated with various receptor agonists. In biopsies and GECs, mRNA expression of human beta-defensins (hBD-2, hBD-3), CC-chemokine ligand 20 (CCL20), S100A7/psoriasin (S100A7), and calgranulin A/B (S100A8, S100A9) was evaluated using real-time PCR, and protein profiles were measured by ELISA. Statistical analysis was performed using non-parametric tests. Results: The clinical parameters BOP, PI and GCF increased over time (p < 0.0001). Tissue AMP mRNA expression was elevated, but at different and AMP-specific time points (p < 0.05). Protein analysis revealed a similar expression pattern for hBD-2 and CCL20 in GCF (p < 0.05). In GECs, multiple receptor stimulation was required to induce AMP gene expression (p < 0.0001). Conclusions: For the first time, this study showed the sequential and differential expression of AMPs during a developing inflammation in vivo providing further evidence for their role as guardians of a healthy periodontium.