Salivary Total Protease Activity Based on a Broad-Spectrum Fluorescence Resonance Energy Transfer Approach to Monitor Induction and Resolution of Gingival Inflammation

Abstract

Objective: Salivary total protease and chitinase activities were measured by a broad-spectrum fluorescence resonance energy transfer approach as predictors of induction and resolution of gingival inflammation in healthy individuals by applying an experimental human gingivitis model.

Methods: Dental biofilm accumulated (21 days, Induction Phase) by omitting oral hygiene practices followed by a 2-week Resolution Phase to restore gingival health in an experimental gingivitis study. Plaque accumulation, as assessed by the Turesky Modification of the Quigley-Hein Plaque Index (TQHPI), and gingival inflammation, assessed using the Modified Gingival Index (MGI), scores were recorded and unstimulated saliva was collected weekly. Saliva was analysed for total protein, albumin, total protease activity and chitinase activity (n = 18).

Results: The TQHPI and MGI scores, as well as total protease activity, increased until day 21. After re-establishment of oral hygiene, gingival inflammation levels returned to values similar to baseline (day 0). Levels of protease activity decreased significantly, but not to baseline values. Furthermore, 'fast' responders, who responded immediately to plaque, exhibited significantly higher proteolytic activity throughout the experimental course than 'slow' responders, who showed a lagged inflammatory response.

Conclusion: The results indicate that differential inflammatory responses encompass inherent variations in total salivary proteolytic activities, which could be further utilised in contemporary diagnostic, prognostic and treatment modalities for periodontal diseases.

Fig. 1

Flowchart of patient recruitment and participation (see also Dataset II from Nascimento et al. [42]). In total, saliva samples from 18 individuals were available for analysis from the 42 individuals who completed the study

Fig. 2

Results from mixed-effects multilevel models. a Mean TQHPI score as a function of day of experiment and pattern of gingival inflammation response. b Mean MGI score as a function of mean TQHPI, day of experiment and pattern of gingival inflammation response. Estimates given are the standardised regression coefficients (95% confidence interval). MGI modified gingival index, TQHPI Turesky Modification of the Quigley-Hein Plaque Index

Fig. 3

Results from mixed-effects multilevel models. a Salivary protease level and as a function of day of experiment. b Salivary chitinase level as a function of day of experiment. Estimates given are the standardised regression coefficients (95% confidence interval). Both analyses were adjusted for the standardised protein level