Relationship between fibrinolytic activity and gingival inflammatory reaction in young individuals

The fibrinolytic system (the plasminogen activating system) is involved in several physiological and pathological processes. Through the transformation of plasminogen to the aggressive broad spectrum protease plasmin, potent enzymatic activity is released. Plasmin acts directly on connective tissue components, and indirectly by activating proforms of the metalloproteinases. The destructive potential of the fibrinolytic system may thus be of importance for the initiation and progression of periodontal diseases. Earlier studies have shown high concentrations of the plasminogen activator t-PA and its inhibitor PAI-2 in gingival crevicular fluid (GCF) as well as enhanced concentrations in areas of gingival inflammation. The aim of this study was to investigate a possible relationship between the gingival inflammatory reactivity and the fibrinolytic activity in gingival crevicular fluid. Thirty-one young individuals took part in the study. Gingival Index scores and Plaque Index scores were assessed and used to formulate a score expressing an individuals' inflammatory response to microbial plaque levels (Relative G/P score). The fibrinolytic activity of GCF was assessed with a fibrin gel lysis assay, and the levels of t-PA and PAI-2 were assayed with ELISAs. All samples showed fibrinolytic activity. A positive correlation between the fibrinolytic activity and Relative G/P score was found. Thus, in individuals with an enhanced reactivity to dental plaque, a higher plasminogen activating activity in GCF was seen. This indicates a higher potential for tissue proteolysis in these individuals, possibly facilitating spread and deeper involvement of the lesions.