Circulating MiRNAs as Biomarkers for Non-invasive Diagnostics of Chronic Periodontitis

Objectives: Despite the high prevalence and adverse systemic health effects of chronic periodontitis (CP), the etiopathological pathways of inflammation in periodontal tissues are still not definite resulting in the lack of accurate diagnostic methods and periodontitis-specific pharmacological therapy options. The discovery of epigenetic regulation has advanced the knowledge of ethiopathological pathways of multiple diseases, including CP, enabling new diagnostic and treatment alternatives. Epigenetic regulation through microRNAs (miRNAs) in periodontal disease has significant impact on periodontal homeostasis by regulating both anabolic and catabolic processes, including osteoblast and osteoclast differentiation, inflammatory cytokine production, etc. By using high-throughput technology, the current study aims to access CP-associated miRNAs and evaluate the utility of miRNA for lowly- and non-invasive diagnostic applications.
Methods: Periodontitis-affected and healthy gingival tissues and liquid biopsy samples (plasma and saliva) were collected from 80 patients at Vilnius University Hospital Zalgiris and Santaros Clinics. Periodontal status was evaluated by researcher periodontist performing full mouth probing in accordance with “Centre for Disease Control-American Academy of Periodontology” guidelines. Genome-wide analysis of 24 gingival samples was performed by using Human miRNA Microarrays (8x60K format). Identified changes were validated in 80 tissues and selected miRNAs were further tested in corresponding fluids by using real time PCR method.
Results: Numerous differently expressed miRNAs were observed in periodontitis-affected inflamed gingiva compared to healthy gingiva (P<0.05, fold change ≥2.0). Patients with periodontal disease had 3-fold higher plasma level of miR-31 (P=0.024) and 2-fold lower level of miR-335 (p=0.011). Level of periodontal patients’ salivary miR-31 was 15 times higher (P<0.001) in compare to plasma level.
Conclusions: Genome-wide miRNA analysis contributes to a deeper understanding of etiopathological pathways of inflammation in CP while levels of circulating miRNAs accurately represent chronic periodontitis clinical status and may be considered as diagnostic markers of the disease.