Plasminogen activator system in smokers and non-smokers with and without periodontal disease

Background: The present study assessed levels of plasminogen activator (PA) system proteins in gingival crevicular fluid (GCF) and serum of chronic gingivitis, chronic periodontitis patients and periodontally healthy subjects and evaluated how smoking influenced these levels. Methods: Twenty chronic gingivitis; 20 chronic periodontitis patients and 20 periodontally healthy volunteers were consecutively recruited according to the inclusion criteria so that exactly half of the subjects in each category were smokers. GCF samples from four sites together with serum samples were obtained from each subject. GCF levels of tissue type PA (t-PA), urokinase type PA (u-PA), PA inhibitor-1 (PAI-1) and PA inhibitor-2 (PAI-2) and serum concentrations of cotinine, u-PA and PAI-1 were analysed by enzyme-linked immunosorbent assay. Results: The only statistically significant difference between smokers and nonsmokers was a lower GCF PAI-2 concentrations in healthy smokers compared with healthy non-smokers (p<0.01). Gingivitis and periodontitis patients had higher GCF concentrations of PAI-2 than healthy subjects (p < 0.002 and p < 0.02 respectively). The ratio of u-PA:PAI-1 and t-PA:PAI-1 were significantly higher in GCF of smokers with periodontitis compared with "healthy" smokers, whereas the ratio of t-PA:PAI-2 was significantly lower in smokers with periodontal disease (p < 0.05). Conclusions: GCF levels of the PA system proteins are increased in chronic gingivitis and periodontitis compared with healthy gingiva. Smoking had only subtle effects on the GCF PA system proteins with the exception of PAI-2, and the balance of activators and inhibitors. These findings suggest one mechanism whereby smoking may exert detrimental effects on the periodontal tissues.