Salivary cystatin activity and cystatin C in natural and experimental gingivitis in smokers and non-smokers

Background: Recent studies show that subjects with natural gingivitis or periodontitis have elevated levels of salivary cystatins compared to periodontally healthy individuals. Increased glandular output of cystatins in inflammatory conditions suggests an active, most likely protective, role for these proteins in inflammatory processes. Furthermore, it has been shown that the development of gingival inflammation is suppressed in smokers during experimental gingivitis. Aims: The purpose of the present study was to investigate whether (i) the levels of salivary cystatins in natural gingivitis are related to smoking status, and (ii) to study whether experimentally induced gingivitis is associated with changes in salivary cystatin levels, in both smokers and non-smokers. Material and Methods: Whole saliva samples were taken in relation to natural gingivitis, gingival health and 14-day experimental gingivitis in 25 non-dental students (14 non-smokers and 11 smokers). The salivary flowrate was determined. Samples were analyzed for levels of protein, cystatin and cystatin-C. Results: Salivary flow and protein concentrations in cleared human whole saliva samples of non-smokers and smokers were not different from each other at any timepoint during the trial. With regard to cystatins, the results showed that in the state of natural gingivitis cystatin activity is lower in smokers as compared to non-smokers. In smokers, the resolution of natural gingivitis to the state of gingival health did not result in a change of cystatin activity and levels of cystatin C. At the end of the 14-day experimental gingivitis period, smokers showed a decrease in cystatin activity and cystatin C as well as lower outputs of cystatin activity and cystatin C. Conclusion: Smoking is associated with lower cystatin activity and output of cystatin C during gingival inflammation.