title: Correlation of expression and activity of matrix metalloproteinase-9 and -2 in human gingival cells of periodontitis patients.
abstract: OBJECTIVE
  Matrix metalloproteinases (MMPs) are capable of degrading extracellular matrix, and they are inducible enzymes depending on an inflammatory environment such as periodontitis and bacterial infection in periodontal tissue. Gingival inflammation has been postulated to be correlated with the production of MMP-2 and MMP-9. The objective of this study was to quantify the expression and activity of MMP-9 and -2, and to determine the correlation between activity and expression of these MMPs in human gingival tissues with periodontitis.
  
  
  METHODS
  The gingival tissues of 13 patients were homogenized in 500 µL of phosphate buffered saline with a protease inhibitor cocktail. The expression and activity of MMP-2 and -9 were measured by enzyme-linked immunosorbent assay and Western blot analysis, and quantified by a densitometer. For the correlation line, statistical analysis was performed using the Systat software package.
  
  
  RESULTS
  MMP-9 was highly expressed in all gingival tissue samples, whereas MMP-2 was underexpressed compared with MMP-9. MMP-9 activity increased together with the MMP-9 expression level, with a positive correlation (r=0.793, P=0.01). The correlation was not observed in MMP-2.
  
  
  CONCLUSIONS
  The expression of MMP-2 and -9 might contribute to periodontal physiological and pathological processes, and the degree of MMP-9 expression and activity are predictive indicators relevant to the progression of periodontitis.
authors.affiliation: Department of Orthodontics, Kyung Hee University School of Dentistry, Seoul, Korea.
authors.forename: Kyung-A
authors.initials: KA
authors.lastname: Kim
authors.forename: Soo-Bong
authors.initials: SB
authors.lastname: Chung
authors.forename: Eun-Young
authors.initials: EY
authors.lastname: Hawng
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Noh
authors.forename: Kwon-Ho
authors.initials: KH
authors.lastname: Song
authors.forename: Hanna-Hyun
authors.initials: HH
authors.lastname: Kim
authors.forename: Cheorl-Ho
authors.initials: CH
authors.lastname: Kim
authors.forename: Young-Guk
authors.initials: YG
authors.lastname: Park
keywords: Matrix metalloproteinase 2; Matrix metalloproteinase 9; Periodontitis