Quantitative proteomic analysis of whole saliva and candidate predictive biomarkers for early childhood caries

We aimed to characterize the salivary proteomic profile and the salivary protein expression in children with and without early childhood caries (ECC) in order to identify salivary protein biomarkers for ECC. We recruited 56 children into the ECC (n = 28) and caries-free (n = 28) groups. Stimulated whole saliva was collected on ice, followed by protein analysis using a label-free proteomic technique. Moreover, we performed a multidisciplinary bioinformatic analysis. Proteomic analysis revealed significant between-group differences in the salivary protein expression profiles. Based on the protein-protein interaction network analysis and protein function identification, we identified L-lactate dehydrogenase as a potential biomarker. Accordingly, in a validation study, we performed an enzyme-linked immunosorbent assay to detect the differential expression of salivary L-lactate dehydrogenase between 20 preschool children with ECC and 19 caries-free children. The ECC children had significantly higher levels of L-lactate dehydrogenase than the caries-free children, which suggests its predictive utility for ECC. Taken together, our findings suggest that L-lactate dehydrogenase, as well as peroxiredoxin-5, glucose-6-phosphate-1-dehydrogenase, glutathione reductase, malate dehydrogenase, and talin-1, may be potential biomarkers of ECC.