Saliva/pathogen biomarker signatures and periodontal disease progression

Abstract

The purpose of this study was to determine the role of saliva-derived biomarkers and periodontal pathogens during periodontal disease progression (PDP). One hundred human participants were recruited into a 12-month investigation. They were seen bi-monthly for saliva and clinical measures and bi-annually for subtraction radiography, serum and plaque biofilm assessments. Saliva and serum were analyzed with protein arrays for 14 pro-inflammatory and bone turnover markers, while qPCR was used for detection of biofilm. A hierarchical clustering algorithm was used to group study participants based on clinical, microbiological, salivary/serum biomarkers, and PDP. Eighty-three individuals completed the six-month monitoring phase, with 39 [corrected] exhibiting PDP, while 44 [corrected] demonstrated stability. Participants assembled into three clusters based on periodontal pathogens, serum and salivary biomarkers. Cluster 1 members displayed high salivary biomarkers and biofilm; 71% [corrected] of these individuals were undergoing PDP. Cluster 2 members displayed low biofilm and biomarker levels; 76% [corrected] of these individuals were stable. Cluster 3 members were not discriminated by PDP status; however, cluster stratification followed groups 1 and 2 based on thresholds of salivary biomarkers and biofilm pathogens. The association of cluster membership to PDP was highly significant (p < 0.0007). [corrected] The use of salivary and biofilm biomarkers offers potential for the identification of PDP or stability (ClinicalTrials.gov number, CT00277745).

Trial registration: ClinicalTrials.gov NCT00277745.

Figure 1.

Study timeline and recruitment/enrollment activities of the study. (A) Study timeline. (B) The study population was stratified into four groups.

Figure 2.

Longitudinal plots of mean (± SD) clinical periodontal measures stratified by initial category of periodontal health. Compared with baseline, individuals in the mild and moderate/severe periodontitis groups showed significant mean PD reductions at 8, 10, and 12 mos; those in the gingivitis group had significant mean PD reductions at 8 and 10 mos (p < 0.05). Compared with baseline CAL, gingivitis and periodontitis groups had significant gains at 8, 10, and 12 mos; individuals in the healthy group had significant gains in CAL at 8 and 10 mos (p < 0.05). Significant radiographic bone gain was achieved in the mild periodontitis group at 12 mos compared with baseline (p < 0.05). Compared with baseline, significant percent reductions in the percent of sites with bleeding upon probing were seen in the gingivitis and periodontitis groups at 8, 10, and 12 mos (p < 0.05). Significant reductions in the percent of sites with plaque were observed in the periodontitis groups at 8, 10, and 12 mos compared with baseline; healthy individuals and those in the gingivitis group had significant reductions at 10 mos compared with baseline (p < 0.05). Significant reductions in the percent of sites with redness were achieved by individuals in the periodontitis groups at 8 and 12 mos compared with baseline; those in the healthy group had significant increases in the percent of redness at 12 mos compared with baseline (p < 0.05).

Figure 3.

Longitudinal plots of mean (± SD) salivary biomarker levels stratified by initial category of periodontal health. Compared with baseline, significant reductions in salivary MMP-8 were seen in the moderate/severe periodontitis group at 8, 10, and 12 mos; those in the healthy group showed significant increases in MMP-8 levels at 12 mos (p < 0.05). Participants in the moderate/severe periodontitis group had significant reductions in MMP-9 at 10 and 12 mos compared with baseline; those in the healthy group had significant increases in MMP-9 at 10 and 12 mos compared with baseline (p < 0.05). Individuals in the periodontitis group had significant reductions in salivary OPG levels at 12 mos compared with baseline (p < 0.05). Compared with baseline levels of calprotectin, participants in the moderate/severe periodontitis group showed significant increases at 8, 10, and 12 mos; those in the mild periodontitis group had increases at 8 and 12 mos; those in the gingivitis group had increases at 8 and 10 mos; and those in the healthy group had increases at 8, 10, and 12 mos (p < 0.05). Significant increases in salivary ICTP were observed in the mild periodontitis and gingivitis groups at 12 mos compared with baseline (p < 0.05). Compared with baseline, significant decreases in IL-1β levels were seen in the periodontitis groups at 8, 10, and 12 mos, in the gingivitis group at 8 and 10 mos, and in the healthy group at 10 mos (p < 0.05).

Figure 4.

Barplots displaying three clusters based on levels of salivary biomarkers, biofilm, serum biomarkers, and clinical measures. Within each cluster, the number of participants undergoing disease progression (≥ 2 sites demonstrating > 2 mm of CAL loss over 6 mos) is indicated. Np = number of participants within each group experiencing disease progression. Ns = number of participants within each group without disease progression.