Decitabine Inhibits Osteoclastogenesis and Periodontal Bone Loss in Mice

Objectives: Periodontitis is a common chronic inflammatory disease which is initiated by a complex microbial biofilm. We have previously shown that DNA methylation is involved in periodontal inflammation that may contribute to periodontal disease susceptibility. We sought to determine whether DNA methyl transferase inhibitor namely, Decitabine (5-aza-2’-deoxycytidine) can protect experimentally induced bone loss in mice.
Methods: We used a ligature induced periodontitis mouse model to determine the effects of Decitabine in C57BL/6J mice. Decitabine (1 mg/kg) or vehicle was applied for 5 days. Mice were sacrificed and the gingiva was excised for real-time PCR. Bone loss measurement was done by defleshing, bleaching the maxilla and subjecting it to manual measurement as well as microtomography. Images were captured and the distance between the cementoenamel junction (CEJ) - alveolar bone crest (ABC) was measured using a Nikon Digital Sight DS-U3 system. Paraffin sections of maxilla were used for TRAP staining and immunofluorescence. CD14+ monocytes were used to examine the effects of Decitabine for osteoclastogenesis in vitro. Luciferase reporter assays were performed to unravel transcriptional activation.
Results: We observed severe bone loss in the ligature induced periodontitis model and Decitabine significantly inhibited the bone loss. We found that the treatment with Decitabine significantly reduced osteoclasts both in vivo and in vitro and up-regulated the anti-inflammatory cytokines (IL-10 and TGF-β) in vitro. Bioinformatic analysis revealed that Krüppel-like Factor 2 (KLF2) is highly guanine-cytocine rich, and possess a long CpG island spanning the entire gene. As expected, Decitabine increased KLF2 mRNA expression. Luciferase reporter assay showed KLF2 up-regulated the transcriptional activity of CCAAT/enhancer binding protein beta (CEBPB) and the anti-inflammatory cytokines IL-10 and TBF-β.
Conclusions: Decitabine inhibits alveolar bone loss by limiting osteoclastogenesis in mice and shows KLF2 can regulate that. Taken together, Decitabine may have utility in treating chronic inflammatory periodontal disease in humans.