Inhibitory effects of green tea polyphenol (-)-epigallocatechin gallate on the expression of matrix metalloproteinase-9 and on the formation of osteoclasts.
BACKGROUND
Alveolar bone resorption is a characteristic feature of periodontal diseases and involves the removal of both the mineral and organic constituents of the bone matrix, which is caused by either multinucleated osteoclast cells or matrix metalloproteinases (MMPs). The gram-negative bacterium, Porphyromonas gingivalis has been reported to stimulate the activity and expression of several groups of MMPs, whereas (-)-epigallocatechin gallate (EGCG), the main constituent of green tea polyphenols, has been reported to have inhibitory effects on the activity and expression of MMPs.


OBJECTIVE
In the present study, we investigated the effects of the green tea polyphenol, EGCG, on the gene expression of osteoblast-derived MMP-2, -9 and -13, stimulated by P. gingivalis, and on the formation of osteoclasts.


METHODS
The effect of EGCG on the gene expression of MMPs was examined by treating mouse calvarial primary osteoblastic cells with EGCG (20 microM) in the presence of sonicated P. gingivalis extracts. The transcription levels of MMP-2, -9 and -13 were assessed by reverse transcription-polymerase chain reaction (RT-PCR). The effect of EGCG on osteoclast formation was confirmed by tartrate-resistant acid phosphatase (TRAP) staining in a co-culture system of mouse bone marrow cells and calvarial primary osteoblastic cells.


RESULTS
Treatment with the sonicated P. gingivalis extracts stimulated the expression of MMP-9 mRNA and this effect was significantly reduced by EGCG, whereas the transcription levels of MMP-2 and MMP-13 were not affected by either the sonicated P. gingivalis extracts or EGCG. In addition, EGCG significantly inhibited osteoclast formation in the co-culture system at a concentration of 20 microM.


CONCLUSIONS
These findings suggest that EGCG may prevent the alveolar bone resorption that occurs in periodontal diseases by inhibiting the expression of MMP-9 in osteoblasts and the formation of osteoclasts.
Yun
Jeong-Ho
JH
Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul, Korea.
Pang
Eun-Kyoung
EK
Kim
Chang-Sung
CS
Yoo
Yun-Jung
YJ
Cho
Kyoo-Sung
KS
Chai
Jung-Kiu
JK
Kim
Chong-Kwan
CK
Choi
Seong-Ho
SH
D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001854:Bone Marrow Cells / Q000187:drug effects; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D061965:Matrix Metalloproteinase Inhibitors; D051379:Mice; D008813:Mice, Inbred ICR; D010006:Osteoblasts / Q000187:drug effects / Q000201:enzymology*; D010010:Osteoclasts / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology*; D016966:Porphyromonas gingivalis / Q000502:physiology; D011480:Protease Inhibitors / Q000494:pharmacology*; D012333:RNA, Messenger / Q000096:biosynthesis; D018709:Statistics, Nonparametric; D013662:Tea / Q000737:chemistry*
D017077:Culture Media, Conditioned; D061965:Matrix Metalloproteinase Inhibitors; D010936:Plant Extracts; D011480:Protease Inhibitors; D012333:RNA, Messenger; D013662:Tea; D002392:Catechin; C045651:epigallocatechin gallate