Polyphenols from Myrothamnus flabellifolia Welw. inhibit in vitro adhesion of Porphyromonas gingivalis and exert anti-inflammatory cytoprotective effects in KB cells

P>Aim Identification of anti-adhesive plant extracts against cell surface binding of Porphyromonas gingivalis and underlying mechanisms; investigation of potential cytoprotective effects of anti-adhesive extract on KB cells. Materials and Methods Polyphenol-enriched extract, fully characterized concerning flavan-3-ols and oligomeric proanthocyanidins, from Myrothamnus flabellifolia (MF), traditionally used for periodontitis, was tested for inhibition of P. gingivalis-mediated adhesion to KB cells by flow cytometry, for influence on gingipain activity (protease assay), haemagglutination and by microarray analysis for effects on bacterial transcriptome. The influence of MF on P. gingivalis-induced cytokine gene expression was monitored by RT-PCR and IL-6 titres by ELISA. Results MF (100 mu g/ml) reduced P. gingivalis adhesion/invasion about 50% by interacting with bacterial OMPs. As shown by RT-PCR, fimbrillin and Arg-gingipain encoding genes were up-regulated by MF. On the protein level, inhibition (70%) of Arg-gingipain activity was observed, while the corresponding Lys-gingipain was hardly influenced. MF also inhibited haemagglutination. While exposure to P. gingivalis resulted in an increased expression of inflammation-related genes in KB cells, pre-treatment of KB cells with MF evoked cytoprotective effects concerning IL-1 beta, IL-6, IL-8 and TNF-alpha gene expression as well as IL-6 release rates. Compounds from the plant extract belonging to the class of proanthocyanidins were shown to be responsible for the observed effects and were characterized for their respective structural features. Conclusions While being cytoprotective, MF exerts anti-adhesive effects against P. gingivalis. Thus, MF may be useful for the prevention of P. gingivalis-associated periodontal diseases.