The purpose of the present study was to determine the effect of tetracycline analogues on the activity of MMP-3. Tetracycline-HCl, doxycycline-HCl, and minocycline-HCl were applied to huamn gingival fibroblasts at various concentrations of 10, 25, 50, 100, 200µg/ml, and 1 hour later IL-1β of 25ng/ml was added. After incubation for 24 hours the cells were reacted by enzyme-linked immunosorbent assay using proMMP-3 ELISA kit. The optical density was measured by microwell plate reader at 450nm. The relative activity of MMP-3 was calculated as the percentage of the optical density of each experimental group to that of the control. The difference of the optical density and the relative activity of MMP-3 between the experimental groups and the control wasstatistically analyzed by one way ANOVA.

The results were as follows:

1. Tetracycline-HCl showed the tendency to inhibit the activity of MMP-3 at the concentration lower than 25 µg/ml, but increased significantly the activity of MMP-3 at the concentration of 200microgram/ml(p<0.05).

2. Doxycycline-HCl inhibited significantly the activity of MMP-3 at the concentration lower than 100µg/ml, but increased significantly the activity of MMP-3 at the concentration of 200µg/ml(p<0.05).

3. Minocycline-HCl inhibited the activity of MMP-3 at the concentration in the range of 10 to 200µg/ml.

Within the limit of the present study, the above results suggested that the low concentration of tetracycline analogues could inhibit the activity of MMP-3 induced by IL-1β in human gingival fibroblasts.