Analysis of in situ protease activity in chronic adult periodontitis patients: Expression of activated MMP-2 and a 40 kDa serine protease

Background: Periodontitis is characterized by extensive destruction of the gingival tissues and associated supporting structures of the teeth. Althoug h the pathogenesis of the various forms of this disease is not completely u nderstood, host-derived proteases are believed to have an important role. I n this study, we analyzed human tissue samples from chronic adult periodont itis patients to assess the levels of specific proteases and determine the effect of pH and tetracyclines on their activity. Methods: Gingival tissue samples were obtained from patients with chronic a dult periodontitis (probing depths ranged from 5 to 9 mm) and periodontally healthy controls. Tissue extracts were prepared and analyzed for protease activity by zymography and Western blotting. Results: Maximal protease activity from clinically normal and diseased tiss ues was observed at pH 8. Latent matrix metalloproteinase (MMP)-9 and MMP-2 were expressed in all samples examined, while active MMP-2 was detected on ly in tissues obtained from patients with clinical disease. The MMP activit ies were differentially inhibited by derivatives of tetracycline. At pH 6, a protease with a mass of approximately 40 kDa was observed in diseased sam ples. The enzymatic activity was inhibited by phenylmethylsulfonyl fluoride , suggesting it is a serine protease. Conclusions: The results of the current study substantiate the proposed rol e of host-derived proteases in the pathogenesis of chronic adult periodonti tis. Specifically, they indicate that activated MMP-2 and a 40 kDa serine p rotease are involved in tissue destruction associated with this form of per iodontal disease and also suggest that tissue pH influences protease activi ty in situ.