Expression of mRNA for matrix metalloproteinases and tissue inhibitors of metalloproteinases in periodontitis-affected human gingival tissue

It is known that the host responds to an increased concentration of collagenase [or matrix metalloproteinase (MMP)-1] by preferentially expressing mRNA for the tissue inhibitor of metalloproteinase-1 (TIMP-1) in order to overcome tissue destruction due to periodontitis. To further elucidate the relation between MMPs and TIMPs in periodontitis-affected tissues, the expression of mRNA for MMP-1, -3 and -8, and TIMP-1 and -2, in 10 gingival samples from patients and five from healthy individuals was assessed by reverse transcription-polymerase chain reaction. The diseased group showed significantly higher levels of MMP-1, -3, -8 and TIMP-1 mRNA relative to β-actin than the control group (mean ± SE: diseased vs healthy (%): 0.26 ± 0.05 vs 0.018 ± 0.0040 for MMP-1; 0.90 ± 0.16 vs 0.063 ± 0.016 for MMP-3; 0.068 ± 0.017 vs 0.006 ± 0.0010 for MMP-8; 12.66 ± 2.90 vs 2.71 ± 0.54 for TIMP-1; p < 0.01). TIMP-2 did not significantly differ between the two groups (1.79 ± 0.33 vs 1.42 ± 0.53; p > 0.05). The preferential increase in the level of MMP-3 mRNA relative to that of MMP-1 and -8 in inflamed gingiva would be relevant to tissue destruction because MMP-3 is a broad-spectrum MMP and a pivotal activator of latent MMP-1 and -8. Therefore, the overall increase in MMP-1, -3 and -8 mRNA in periodontitis-affected gingiva might account for a concerted action of MMPs during connective tissue destruction in periodontitis.