Matrix metalloproteinases‐1 and ‐8 and TIMP‐1 mRNA levels in normal and diseased human gingivae

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Abstract
Interstitial collagenases, including matrix metalloproteinase‐1 (MMP‐1) and ‐8 (MMP‐8), serve as initiators of extracellular matrix destruction in periodontal disease. Collagenase activities are mainly regulated by tissue inhibitors of metalloproteinases (TIMPs). We tested the effects of inflammation on MMP‐1 and MMP‐8 gene expression in periodontal disease. To determine the relative abundance of these mRNAs in gingiva, we used a reverse transcription‐polymerase chain reaction (RT‐PCR) assay. Gingival biopsies were divided into 2 groups; a control group and an inflamed group with severe gingivitis or periodontitis. The MMP‐1 mRNA levels were significantly elevated in inflamed gingiva, while the levels of the MMP‐8 transcript were not different in the 2 groups and barely detectable by RT‐PCR assay. The expression of the TIMP‐1 gene was not altered, and remained higher than any of these other genes in both control and diseased gingivae. These results suggest that MMP‐1 rather than MMP‐8 may play an important role in the initiation of collagen degradation in periodontal disease. However, the possibility remains that MMP‐8 plays an important role in periodontal tissue destruction, since the mRNA abundance and not the enzyme activity was assessed.