Patterns of salivary analytes provide diagnostic capacity for distinguishing chronic adult periodontitis from health

Abstract

Salivary biomarker discovery requires identification of analytes with high discriminatory capacity to distinguish disease from health, including day-to-day variations that occur in analyte levels. In this study, seven biomarkers associated with inflammatory and tissue destructive processes of periodontal disease were investigated. In a prospective cohort study design, analyte expression levels were determined in unstimulated whole saliva samples collected on multiple occasions from 30 healthy adults (i.e., orally and systemically) and 50 chronic adult periodontitis patients. Salivary levels of IL-1β, IL-6, MMP-8, and albumin were significantly elevated (5.4 to 12.6X) and levels of IFNα were consistently lower (8.7X) in periodontitis patients compared with the daily variation observed in healthy adults. ROC analyses of IL-1β, IL-6 and MMP-8 yielded areas under the curves of 0.963-0.984 for discriminating periodontitis from health. These results demonstrate that levels of salivary bioanalytes of patients who have periodontitis are uniquely different from normal levels found in healthy subjects, and a panel consisting of IL-1β, MMP-8 and IL-6 shows particular diagnostic potential.

Figure 1

Distribution of (A) salivary IL-1β, MMP-8 and IL-6 and (B)salivary PGE₂, TNFα, IFNα and albumin levels in healthy subjects (control) and periodontitis patients. The open circles (○) denote measures for 6 individual saliva samples from 30 healthy subjects. The 6 samples are plotted in sequence for each subject. The solid circles (●) denote one sample from each of 50 chronic adult periodontitis patients. The horizontal line describes the threshold value determined from the healthy samples, which is also detailed for each analyte.

Figure 1

Distribution of (A) salivary IL-1β, MMP-8 and IL-6 and (B)salivary PGE₂, TNFα, IFNα and albumin levels in healthy subjects (control) and periodontitis patients. The open circles (○) denote measures for 6 individual saliva samples from 30 healthy subjects. The 6 samples are plotted in sequence for each subject. The solid circles (●) denote one sample from each of 50 chronic adult periodontitis patients. The horizontal line describes the threshold value determined from the healthy samples, which is also detailed for each analyte.

Figure 2

Receiver Operator Characteristic (ROC) curves for IL-1β, IL-6 and MMP-8, IFNα and albumin. These determinations were performed using only the initial saliva sample from the healthy subjects.

Figure 3

(A) ROC analysis for three combined analytes with AUC value. (B) 3-dimensional representation of the subject response profiles for the 3 analytes. Each red circle denotes a periodontitis patients and each blue star signifies the baseline sample for a healthy subject. The oval highlights analytes profile levels that identify healthy subjects.

Figure 4

Parallel coordinates plot for each analyte in order of importance determined from Random Forests Analysis.