Periodontal Therapy Influences DNA Methylation of Inflammatory Genes in Chronic Periodontitis=La terapia parodontale influenza la metilazione del DNA di geni infiammatori nella malattia parodontale cronica

Aim: To evaluate the influence of periodontal therapy on epigenetic modifications in chronic periodontitis patients compared to healthy individuals. Methods: Ten patients with healthy periodontium and ten patients with chronic moderate periodontitis were enrolled. Gingival biopsies were collected at baseline for both groups and at 2 & 8 weeks post-periodontal therapy for the disease group (from normal and periodontitis sites). Random-intercept linear regression models were applied to evaluate methylation levels across groups at baseline and to assess changes in the disease group overtime, separately for normal and periodontitis sites. Results: Periodontal therapy restored methylation levels of TNF-α, IFN-γ and COX-2 genes in periodontitis sites after 2 & 8 weeks to levels reported in normal sites. A DNA methylation gradient of COX-2 promoter region was observed at baseline for healthy group and periodontitis group (percentage mean in normal sites = 8.8 ± 5.7, p= 0.47 vs healthy; percentage mean in periodontitis sites = 13.2 ± 7.3, p = 0.03 vs healthy). Maintenance of high LINE-1 methylation on periodontitis sites was observed throughout all data points, suggesting up-regulation of methyltransferase in chronic disease. Conclusions: Periodontal therapy resets the DNA methylation of inflammatory genes to levels observed in normal sites. Maintenance of high levels of DNA methylation was higher in periodontitis sites, reflecting methyl-transferase up-regulation in chronic disease.