Longitudinal investigation of salivary proteomic profiles in the development of early childhood caries

Objectives: To investigate differentially expressed salivary peptides in the development of early childhood caries (ECC) in 3-4 year-old children. Materials and methods: Eighty-two caries-free children at baseline were followed-up for 1 year, during which period 15 of them had developed ECC (Group C), whilst another 15 cases out of the 31 individuals who remained healthy were marked as Group H. Stimulated whole saliva samples were collected at 0, 6 and 12 months, and analyzed using weak cation exchange magnetic beads combined with matrix assisted laser desorption/ionization time-of-flight mass spectrometry. Corresponding peptide mass fingerprints were obtained to develop a discriminating model for ECC development. Q-Exactive mass spectrometry was then performed to identify the possible proteins where these peptides might derive from. Results: Nine peptide peaks were found to be significantly different in Group C among the three sampling time points and might correlate with development of caries. Levels of three of them increased over time, whilst that of the other six decreased gradually. We chose three peptides (1346.6, 2603.5 and 3192.8 Da) which exhibited the best capability of classification, to establish a model for children at high risk of caries. One peptide (1346.6 Da) was identified to be salivary histatin-rich peptide. Conclusions: Our results indicate that peptidomic methods can be applied to help identify new candidate biomarkers for the occurrence and development of ECC. Clinical significance: The change of salivary peptides may be an indicator of ECC, facilitating more effective measures to be taken in prevention of this disease.