Cytoprotective effect of proanthocyanidin-rich cranberry fraction against bacterial cell wall-mediated toxicity in macrophages and epithelial cells.

Recent studies brought evidence regarding the potential beneficial effects of cranberry polyphenols for periodontal infections. In this study, we evaluated the capacity of a proanthocyanidin-rich cranberry fraction to protect macrophages and oral epithelial cells against cytotoxicity induced by bacterial components. U937 cells, differentiated into adherent macrophage-like cells, as well as oral epithelial cells were treated with cell wall or lipopolysaccharide preparations from periodontopathogens. Cell viability was monitored using a commercial MTT (3-[4,5-diethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. The cytoprotective effect was evaluated by pre-incubating human cells with a proanthocyanidin-rich cranberry fraction prior to treatment with the bacterial components at toxic concentrations. Among the various bacterial components tested, Peptostreptotoccus micros cell wall was found to be the most toxic for macrophages and epithelial cells and was thus selected for further analyses. Treatment of monocyte-derived macrophages with cell wall of P. micros (20 microg/ml) decreased the cell viability by approximately 50%. Adding the cranberry fraction prior to treating cells with P. micros cell wall dose-dependently protected monocyte-derived macrophages from the toxic effect. A dose-dependent cytoprotective effect of the cranberry fraction was also observed with oral epithelial cells treated with P. micros cell wall. This study suggests that cranberry polyphenols may exert a protective effect for host cells against the toxicity induced by bacterial components.

Effects of a high-molecular-weight cranberry fraction on growth, biofilm formation and adherence of Porphyromonas gingivalis.

BACKGROUND: Porphyromonas gingivalis is a major aetiological agent of periodontitis, a destructive disease affecting the tooth-supporting tissues. Recent reports have indicated that high-molecular-weight molecules from cranberry juice concentrate can prevent the attachment of human pathogens to host tissues. OBJECTIVES: The aim of the present study was to investigate the effect of non-dialysable material (NDM) prepared from cranberry juice concentrate on growth, biofilm formation and adherence properties of P. gingivalis. METHODS: The effect of cranberry NDM on biofilm formation was studied using a polystyrene microplate assay and by scanning electron microscopy. The effect of cranberry NDM on the attachment properties of P. gingivalis was evaluated by a microplate assay in which mammalian proteins were immobilized into wells. RESULTS: Our results indicated that cranberry NDM is a potent inhibitor of biofilm formation by P. gingivalis. However, it has no effect on growth and viability of bacteria. Cranberry NDM also prevented significantly the attachment of P. gingivalis to surfaces coated with type I collagen, fibrinogen or human serum. CONCLUSIONS: Our data suggest that cranberry constituents may have a beneficial effect for the prevention and treatment of periodontitis by reducing the capacity of P. gingivalis to colonize periodontal sites.