Neutralization of Nicotine-induced Cytotoxic Effects by Green Tea Epigallocatechin Gallate

Objectives: Periodontitis is an inflammatory condition induced by specific bacterial species and which results in destruction of the tooth-supporting tissues. During the last decade, tobacco use has been demonstrated to be one of the most important environmental risk factors for periodontitis. In this study, we evaluated the toxic effect of nicotine, alone or in combination with lipopolysaccharide (LPS) of periodontopathogens (Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis), on oral mucosal cells (epithelial cells, fibroblasts) and investigated the ability of the green tea polyphenol epigallocatechin gallate (EGCG) to neutralize the nicotine-induced cytotoxic effects. Methods: Oral epithelial cells and fibroblasts were cultured in 96-well plates and treated with various concentrations of either nicotine or nicotine + A. actinomycetemcomitans or P. gingivalis LPS in the presence or absence of EGCG. The cell viability was evaluated by a 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay. Results: Nicotine caused a dose-dependent loss of cell viability in epithelial cells and fibroblasts. Mixtures of nicotine with LPS demonstrated additive instead of synergistic effects. EGCG efficiently neutralized the nicotine-induced toxic effects in both cell types. Conclusion: These results suggest that plant-derived polyphenols such as EGCG from green tea offer a promising perspective for the development of a novel preventative/therapeutic agent for periodontitis. This study was supported by the Fondation de l'Ordre des dentistes du Québec.