Older Adults' Salivary Proteomic Is Reshaped by Caries Disease Severity.

Abstract

Introduction: Dental caries is a disease with high prevalence and concern worldwide, especially among the elderly population. Considering the impact of saliva on the disease development process, protein biomarkers may be potentially useful to monitor the clinical course of the disease.

Methods: This study recorded clinical data and conducted a proteomic analysis of the saliva of eighty elderly individuals (60-84 years). Participants were classified into a no active caries (NC) group and low caries activity (LC) and high caries activity (HC) groups. We hypothesized that the protein profile between the groups would be different and could be used to learn about disease progression and identify potential markers for caries severity in the aged population. All participants had their unstimulated total saliva collected for 5 min. Further correlations were tested to find target proteins strongly linked to clinical variables of caries disease, i.e., the visible dental plaque index, root caries experience, salivary flow, buffering capacity and pH, and percentage of sugar intake. To achieve this, groups with different dental caries statuses were compared.

Results: In total, 1,299 proteins were identified, of which 665 could be quantified in all samples. Of these, 16 proteins had statistically different abundances between the groups with and without dental caries activity (p < 0.05; fold-change [FC] 1.23). Furthermore, 31 proteins differentially regulated in saliva, including 22 downregulated and 9 upregulated proteins, were found in the HC group compared with the LC group (p < 0.05; FC 1.23). When correlated with caries disease-related clinical parameters, 87 candidates were identified and 19 maintained significances from the primary data analysis (p < 0.05). In the gene ontology analysis, most of the regulated proteins were related to innate immunity processes, calcium ions activity, action against bacteria, and cell adhesion.

Conclusion: This study identified potential proteins that may help distinguish different caries activity status on people over 60 years of age. Ultimately, future studies could investigate whether the differential abundance of regulated proteins is a result of the caries process itself or the underlying factors that contribute to its development.