title: Green tea catechins potentiate the effect of antibiotics and modulate adherence and gene expression in Porphyromonas gingivalis.
abstract: OBJECTIVE
  A number of studies have brought evidence that green tea catechins may contribute to periodontal health. The objective of this study was to investigate the ability of a green tea extract and its principal constituent epigallocatechin-3-gallate (EGCG) to potentiate the antibacterial effects of antibiotics (metronidazole, tetracycline) against Porphyromonas gingivalis, and to modulate the adherence to oral epithelial cells and expression of genes coding for virulence factors and the high temperature requirement A (HtrA) stress protein in P. gingivalis.
  
  
  METHODS
  A broth microdilution assay was used to determine the antibacterial activity of the green tea extract and EGCG. The synergistic effects of either compounds in association with metronidazole or tetracycline were evaluated using the checkerboard technique. A fluorescent assay was used to determine bacterial adherence to oral epithelial cells. The modulation of gene expression in P. gingivalis was evaluated by quantitative RT-PCR. The Vibrio harveyi bioassay was used for monitoring quorum sensing inhibitory activity.
  
  
  RESULTS
  The MIC values of the green tea extract on P. gingivalis ranged from 250 to 1000 μg/ml, while those of EGCG ranged from 125 to 500 μg/ml. A marked synergistic effect on P. gingivalis growth was observed for the green tea extract or EGCG in combination with metronidazole. Both the green tea extract and EGCG caused a dose-dependent inhibition of P. gingivalis adherence to oral epithelial cells. On the one hand, green tea extract and EGCG dose-dependently inhibited the expression of several P. gingivalis genes involved in host colonization (fimA, hagA, hagB), tissue destruction (rgpA, kgp), and heme acquisition (hem). On the other hand, both compounds increased the expression of the stress protein htrA gene. The ability of the green tea extract and EGCG to inhibit quorum sensing may contribute to the modulation of gene expression.
  
  
  CONCLUSIONS
  This study explored the preventive and therapeutic potential of green tea catechins against periodontal disease. In addition to inhibit growth and adherence of P. gingivalis, a green tea extract and its main constituent EGCG was found to decrease the expression of genes coding for the major virulence factors.
authors: Oral Ecology Research Group, Faculty of Dentistry, Université Laval, Quebec City, Quebec, Canada.
authors: Jade
authors: J
authors: Fournier-Larente
authors: Oral Ecology Research Group, Faculty of Dentistry, Université Laval, Quebec City, Quebec, Canada.
authors: Marie-Pierre
authors: MP
authors: Morin
authors: Oral Ecology Research Group, Faculty of Dentistry, Université Laval, Quebec City, Quebec, Canada. Electronic address: Daniel.Grenier@greb.ulaval.ca.
authors: Daniel
authors: D
authors: Grenier
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D004357:Drug Synergism; D004847:Epithelial Cells / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D010510:Periodontal Diseases / Q000188:drug therapy / Q000382:microbiology / Q000517:prevention & control; D010936:Plant Extracts / Q000494:pharmacology*; D059808:Polyphenols / Q000494:pharmacology; D016966:Porphyromonas gingivalis / Q000187:drug effects* / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D053038:Quorum Sensing / Q000187:drug effects; D057057:Serine Proteases / Q000096:biosynthesis / Q000235:genetics; D013662:Tea / Q000737:chemistry*; D037521:Virulence Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D059808:Polyphenols; D013662:Tea; D037521:Virulence Factors; D002392:Catechin; C045651:epigallocatechin gallate; D057057:Serine Proteases
keywords: Catechins; Green tea; Periodontal disease; Polyphenols; Porphyromonas gingivalis; Virulence factor