Description of the plasminogen activating system in canine gingival crevicular fluid

Abstract Summary Objective : Human gingival crevicular fluid (GCF) contains fibrinolytic activity, which has been suggested to be of significance for the etiology of periodontal diseases. We have previously found plasminogen activators (u-PA and t-PA) as well as PA inhibitors (PAI -1 and PAI-2) in human GCF and gingival tissues. The aim of this study was to evaluate the dog as an experimental animal for studying the fibrinolytic system (the plasminogen activating system) with available reagents and to describe the system in dog cr evicular fluid. Design : Six dogs were used. Samples from untreated gingival areas showing chronic gingivitis were collected with disks of Millipore filter. Fibrinolytic activity was assayed using a preformed fibrin gel in microtiter plates. t-PA as well as PAI-2 were assayed with ELISAs and Western blotting using antibodies against human antigens. Results : All samples showed fibrinolytic activity. The fibrinolytic activity could be completely quenched by antibodies against human t-PA. Antigen concentrations were similar to those found in humans; the median t-PA concentration in GCF from chronic gingivitis was 0.1μg/ml and the median PAI-2 concentration was 1.6μg/ml. Western blotting showed bands in the same kDa positions as for human t-PA and PAI-2. As in humans, both antibodies also revealed high-molecular-weight bands of similar size (130 kDa), which are likely to represent a complex between t-PA and PAI-2. Conclusion : Our results clearly show that the cross-reactivity is genuine and that these antibodies, developed against human antigens, can be used for experimental studies in the dog.