Methods: Saliva samples from 16 patients (eight orthodontic patients without periodontitis and eight with periodontitis) were analyzed, and peptide mass fingerprints were created by scanning MS signals using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) combined with magnetic beads. Then, The sequences of peptides expressed differentially between the two groups were determined by nano-liquid chromatography-electrospray ionization-tandem mass spectrometry (nano-LC/ESI-MS/MS) using a setup consisting of an Aquity UPLC system (Waters) and an LTQ Obitrap XL mass spectrometer (Thermo Fisher) equipped with a nano-ESI source.
Results: Nine mass peaks showed significant differences, and these differentially-expressed peptides were sequenced. The 3163.4-Da peptide was identified as F2 prothrombin precursor, which is a ‘trypsin-like’ serine protease protein encoded by the F2 gene. Isoform 1 of fibrinogen alpha chain precursor (FGA), which was the predicted identity of the 3154.4- and 2621.9-Da peptides, is encoded by FGA.
Conclusions: The elucidated biomarkers indicated interactions between periodontal condition and orthodontic treatment. Our results provide novel insight into the altered salivary protein profile during periodontal-orthodontic treatment, and may lead to the development of a therapeutic monitoring strategy for periodontics and orthodontics.
(Supported by Peking University School of Stomatology, no: PKUSS20110301)