Antimicrobial responses of primary gingival cells to Porphyromonas gingivalis

Human beta-defensins (hBDs) and the C-C chemokine ligand 20 (CCL20) produced by gingival epithelial cells (GECs) and fibroblasts (HGFs) are antimicrobial peptides (AMPs) that play an important role in innate immunity. The aim of this study was to determine the differential immune response of GECs and HGFs to the oral commensal Streptococcus gordonii (SG) and the pathogen Porphyromonas gingivalis (PG).

In addition to the analysis of gingival biopsies, primary GECs and HGFs were exposed to SG and/or PG, and expression of various AMPs and pro-inflammatory mediators was studied by real-time PCR and ELISA.

Gene expression of AMPs was detected in gingival connective tissue. Both SG and PG induced the mRNA-expression of hBD-2 and hBD-3 in GECs as well as HGFs after 24 h (p < 0.05). In HGFs, the commensal bacterium SG stimulated the mRNAs of hBD-3 and CCL20 after 24 h (p < 0.05), while not in GECs. In GECs, the inductive effect of PG on the mRNA-expression of hBD-2 was amplified when cells were first exposed to commensal SG (for 1 h) prior to stimulation with PG (SG-PG; p < 0.05).

Our data indicate that cell-bacteria interactions and/or bacteria-bacteria cross-talk may have an impact on AMP-regulation in gingiva.