Effect of biologic mediators on ciprofloxacin accumulation by gingival fibroblasts

Human gingival fibroblasts actively accumulate fluoroquinolone antimicrobials. Because fibroblasts are prevalent in gingiva, they may help sustain therapeutic fluoroquinolone levels at that site. The purpose of this study was to determine whether mediators associated with infection or injury can enhance ciprofloxacin accumulation by gingival fibroblasts.

Quiescent fibroblast monolayers were treated for 1, 6, or 24 hours with several concentrations of tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, platelet-derived growth factor (PDGF)-BB, fibroblast growth factor (FGF)-2, or insulin-like growth factor (IGF)-1. Transport was assayed by measuring cell-associated fluoroquinolone fluorescence.

All mediators significantly enhanced ciprofloxacin transport in a dose dependent manner (P < 0.05; ANOVA). Except for TNF, this enhancement was associated with a decrease in the Km of ciprofloxacin transport. Maximal enhancement was observed with 10 ng/ml PDGF or FGF and 30 ng/ml TNF, TGF, or IGF. Brief (1 hour) treatment with TNF or FGF upregulated ciprofloxacin accumulation by a maximum of 13% to 14%, whereas TGF, PDGF, and IGF enhanced this process by 19% to 24%. All of the mediators enhanced ciprofloxacin accumulation by a maximum of 19% to 24% after 6 hours and 30% to 38% after 24 hours. The accumulation of other fluoroquinolones (e.g., gatifloxacin) was also slightly enhanced.

Gingival fibroblasts treated with cytokines or growth factors accumulate significantly more ciprofloxacin than untreated controls. This provides a mechanism by which ciprofloxacin could be preferentially distributed to gingival wound or inflammatory sites, yielding local therapeutic levels that are more sustained than in serum.