Porphyromonas gingivalis lipopolysaccharide stimulation in human periodontal ligament stem cells: role of epigenetic modifications to the inflammation

Periodontitis is a chronic oral inflammatory disease produced by bacteria. Gingival retraction and bone and connective tissues resorption are the hallmarks of this disease. Chronic periodontitis may contribute to the risk of onset or progression of neuroinflammatory pathological conditions, such as Alzheimer's disease. The main goal of the present study was to investigate if the role of epigenetic modulations is involved in periodontitis using human periodontal ligament stem cells (hPDLSCs) as an in vitro model system. hPDLSCs were treated with lipopolysaccharide of Porphyromonas gingivalis and the expression of proteins associated with DNA methylation and histone acetylation, such as DNMT1 and p300, respectively, and inflammatory transcription factor NF-kB, were examined. Immunofluorescence, Western blot and next generation sequencing results demonstrated that P. gingivalis lipopolysaccharide significantly reduced DNA methylase DNMT1, while it markedly upregulated the level of histone acetyltransferase p300 and NF-kB in hPDLSCs. Our results showed that P. gingivalis lipopolysaccharide markedly regulate the genes involved in epigenetic mechanism, which may result in inflammation induction. We propose that P. gingivalis lipopolysaccharide-treated hPDLSCs could be a potential in vitro model system to study epigenetics modulations associated with periodontitis, which might be helpful to identify novel biomarkers linked to this oral inflammatory disease.