The Emerging Role of Salivary Small Extracellular Vesicles in Periodontitis

Objectives: This study aims to investigate whether salivary biological nanoparticles - small extracellular vesicles (sEVs) could act as potential biomarkers for periodontal diseases.
Methods: This study was approved by the University of Queensland (HREC No. 2018001225) and Metro North Hospital and Health Service (approval No. 54584). Whole unstimulated saliva was collected from healthy, gingivitis and periodontitis patients. Small extracellular vesicles were isolated by size exclusion chromatography (SEC), and characterised by morphology with Transmission Electron Microscopy (TEM), by sEVs surface markers with Western Blot and by size distribution with a Nanoparticle Tracking Analysis (NTA). The concentration of sEVs, global DNA methylation and miRNAs profile were correlated with periodontal clinical parameters.
Results: The results showed that the SEC isolation method could lead to more pure and concentrated sEVs particles compared to the ultracentrifuge (UC) method. Furthermore, periodontitis-sEVs significantly increased global 5mC and m6A methylation compared to the healthy group; while there was no change regarding sEVs h5mC methylation between all three groups (Figure 1). The results also demonstrated that periodontitis - salivary sEVs contain higher levels of periodontal pathogens. Furthermore, three significantly increased miRNAs (hsa-miR-140-5p, hsa-miR-146a-5p and hsa-miR-628-5p) were only detected in sEVs in periodontitis when compared to that of healthy controls.
Conclusions: The results indicate that salivary sEVs is a more sensitive sampling method compared to the whole saliva for differentiating various periodontal disease states.