Vitamin D inhibits the growth of and virulence factor gene expression by Porphyromonas gingivalis and blocks activation of the nuclear factor kappa B transcription factor in monocytes

Background and ObjectiveIncreasing evidence suggests that 1,25-dihydroxyvitamin D-3 (1,25(OH)(2)D-3), a fat-soluble secosteroid hormone, has a positive impact on periodontal health through diverse mechanisms. The present study was aimed at investigating the effect of 1,25(OH)(2)D-3 on the growth of and virulence factor gene expression by the periodontopathogenic bacterium Porphyromonas gingivalis. The effect of 1,25(OH)(2)D-3 on P.gingivalis-mediated activation of nuclear factor kappa B (NF-B) transcription factor in monocytes was also assessed. Material and MethodsA broth microdilution assay was used to determine the antibacterial activity of 1,25(OH)(2)D-3. The modulation of virulence factor gene expression in P.gingivalis was assessed by quantitative reverse transcription-polymerase chain reaction. NF-B activation was assessed using a human monocytic cell line stably transfected with a luciferase reporter containing NF-B binding sites. ResultsMinimal inhibitory concentrations of 1,25(OH)(2)D-3 against P.gingivalis ranged from 3.125 to 6.25g/mL. Moreover, a partial synergistic effect was observed when 1,25(OH)(2)D-3 was used in association with metronidazole. 1,25(OH)(2)D-3 attenuated the virulence of P.gingivalis by reducing the expression of genes coding for important virulence factors, including adhesins (fimA, hagA and hagB) and proteinases (rgpA, rgpB and kgp). 1,25(OH)(2)D-3 dose-dependently prevented P.gingivalis-induced NF-B activation in a monocyte model. ConclusionOur study suggested that 1,25(OH)(2)D-3 selectively inhibits the growth of and virulence factor gene expression by P.gingivalis, in addition to attenuating NF-B activation by this periodontopathogen. This dual action on P.gingivalis and the inflammatory response of host cells may be of particular interest with a view to developing a novel and inexpensive preventive/therapeutic strategy.