Matrix Metalloproteinase-2 and -9 Gelatinase Activity in Inflamed Gingiva

Objectives: Matrix metalloproteinases (MMPs) are thought to play a significant role in the degradation of the collagenous structure of inflamed periodontal tissues. We have previously shown a lack of difference in the mRNA expression of various MMPs and TIMP-1 and -2 between healthy and diseased human gingival biopsies. The aim of the present study was to test whether the levels of MMP-2 and -9 gelatinolytic activity would differ among those biopsies.

Methods: 30 gingival samples collected from gingivitis (n=6), advanced chronic periodontitis (n=8), generalized aggressive periodontitis (n=8) and periodontally healthy individuals (n=8, used as controls) were processed for zymographic assay. Equal amounts of protein were loaded onto 8% polyacrylamide gels, co-polymerized with 0.1% gelatin, separated by electrophoresis followed by renaturation and incubation for 20 h at 370C. Gels, after being stained and destained, were scanned and the bands were quantified by optical densitometry (Biorad VersaDoc). Differences among groups were assessed with ANOVA and post hoc Tukey test.

Results: MMP-9 presented a two-fold higher gelatinase activity in the diseased groups compared to control, although a statistical significance was not reached. MMP-2 gelatinase activity was similarly increased, with the exception of the chronic periodontitis group where the MMP-2 bands could barely be visualized. In fact, densitometric analysis for MMP-2 revealed a statistically significant (p<0.01) lower value for the chronic periodontitis compared to the gingivitis group (4,100 ± 5,354 vs. 27,071 ± 6,246).

Conclusion: We conclude that there is a trend for a higher MMP-2 and -9 gelatinolytic activity in the inflamed gingiva. However, the chronically-inflamed periodontal tissue seems to have low MMP-2 gelatinase activity.

Supported in part by: FAPERJ, CNPq and CAPES, Brazil and NIH grant # DE 11004