The study looked at how a mouth bacteria (Fusobacterium nucleatum) affects the production of natural antimicrobial proteins (hBD‑2, hBD‑3, and LL‑37) in a lab model of gum tissue. It found that the bacteria quickly boost hBD‑2 and hBD‑3, but only cause a weak and limited increase in LL‑37, mainly after longer exposure with one bacterial strain.

In the present study, the expression and localization of three epithelial peptides (human β-defensin [hBD]-2 and -3, and cathelicidin [LL-37]) are studied in an organotypic dento-epithelial (OD-E) model exposed to Fusobacterium nucleatum (Fn) biofilm. Biofilm of Fn ATCC 25586 or AHN 9508 were produced by culturing each strain on semipermeable membranes. The OD-E model was constructed by seeding keratinocytes on fibroblast-containing collagen gels and by placing dentin pieces on the top. A 3-day-old biofilm was placed on the top of the OD-E and the coculture was incubated for 5 hours or 24 hours. Production of epithelial antimicrobial peptides was determined immunohistochemically. After 5 hours of incubation, the biofilm of each Fn strain stimulated expression of hBD-2 and -3. hBD-2 was localized on superficial layers and hBD-3 on basal cell layers of the epithelium and dento-epithelial junctions, whereas LL-37 was only weakly expressed. After 24 hours, hBD-2 expression was extended toward basal cell layers of the epithelium. In contrast, hBD-3 expression extended toward superficial layers of the epithelium. In the case of Fn AHN 9508 biofilm, LL-37 was localized in the cell layers of the dento-epithelial junction. In our OD-E model, epithelial antimicrobial peptide responses to Fn biofilms have distinct regulation and localization characteristics, resembling those known to occur in the gingival epithelium in vivo.