SLPI in the GCF of smokers and non-smokers

Objectives: Neutrophil elastase is a powerful protease associated with periodontitis. Smoking is a major risk factor for periodontitis and there have been contrasting reports about elastase activity in gingival crevicular fluid (GCF) and whole mouth saliva (WMS) from smokers and non-smokers. Secretory leukocyte proteinase inhibitor (SLPI) is an inhibitor of elastase in GCF and WMS which is relatively resistant to oxidative damage from cigarette smoking, making it potentially important in the modulation of elastase activity in smokers. This pilot study aimed to compare levels of neutrophil elastase and SLPI in GCF and WMS from smokers and never-smokers with chronic periodontitis.

Methods: GCF and WMS samples were obtained from seven smokers and seven never-smokers with untreated severe chronic periodontitis. The fluid component of GCF and WMS samples was separated from the cell-associated component by centrifugation. Elastase activity was quantified using a substrate assay and SLPI concentrations were determined using an enzyme-linked immunosorbent assay (ELISA). Levels of elastase and SPLI in GCF and WMS, together with the ratio of elastase to SLPI, were compared in smokers and never-smokers.

Results: Active elastase in the cell-associated component of GCF from smokers was significantly lower than never-smokers (unpaired t-test, p=0.02). However, there were no differences in SLPI levels between the two groups in either GCF or WMS. The elastase:SLPI ratio in GCF tended to be higher in never-smokers than smokers and approached significance (Mann Whitney U test, p = 0.1). Power calculations showed 12 subjects would be required in each group to confirm this difference.

Conclusion: In untreated periodontitis, smokers had lower levels of cell-associated elastase in GCF than non-smokers. However, smoking did not reduce SLPI levels in GCF or WMS. A future study would require at least 12 subjects in each group to confirm differences in elastase:SLPI ratios.