Plasminogen activator in human periodontal health and disease

Plasminogen activators, proteases associated with the fibrinolytic system, also play a major part in extravascular processes such as tissue remodelling, cell migration and activation of prohormones, growth factors and other proteases. It is likely that plasminogen activators participate in the pathophysiology of periodontal disease. Plasminogen activator has been identified in human gingival crevicular fluid in a concentration 100-fold greater than in plasma. The local activity of plasminogen activator in gingival tissues was examined and changes detected in its distribution in relation to the extent of disease. Frozen sections from human gingival biopsies were overlaid on fibrin-coated slides; tissue-type plasminogen activator activity was found in all samples. Focal activity was observed in healthy tissue, originating from the most superficial cells of the junctional epithelium. Biopsies of clinically healthy sites obtained 6 weeks after treatment for periodontitis also showed epithelial plasminogen activator activity localized to this area. In contrast, in diseased tissue the entire epithelium lining the periodontal pocket showed activity. This differential pattern of activity in health and disease is consistent with the hypothesis that plasminogen activator is a modulator of periodontal homeostasis.