Background/aims: Antimicrobial peptides such as human beta-defensin-2 (hBD-2), psoriasin (PSO), and ribonuclease 7 (RNase 7) play an important role in innate immunity. The aim of the present study was to test the hypothesis that epithelial cells show a differential gene expression pattern of antimicrobial peptides (hBD-2, PSO, RNase 7) and inflammatory mediators such as interleukin-8 (IL-8) and 5-lipoxygenase (5-LO) in response to different stages of naturally formed biofilms.
Methods: Epithelial cells were cultured from biopsies obtained from five healthy individuals. Native bacterial biofilms were taken from the same subjects that donated the gingival biopsies. To obtain different stages of biofilm formation, polymer disks were attached to prostheses and carried intraorally for 1, 3, 5, and 9 days. The expression of genes for hBD-2, PSO, RNase 7, 5-LO, and IL-8 was examined using semi-quantitative reverse transcription-polymerase chain reaction. The bacterial composition of the individual biofilms was defined using a microarray system (Parocheck), which showed the presence of 20 different bacterial species that are associated with plaque formation.
Results: The expression of the messenger RNAs of hBD-2, RNase 7, and 5-LO was upregulated as a result of the exposure to early biofilm stages, whereas the gene expression of IL-8 was increased in response to matured biofilms. Inter-individual differences in the innate immune response were observed.
Conclusion: The results of the present study showed a time-dependent messenger RNA expression of antimicrobial peptides (hBD-2, RNase 7), 5-LO, and IL-8 in oral epithelial cells responding to different stages of biofilm formation.