Osteoinductive and anti-inflammatory effect of royal jelly on periodontal ligament cells

Royal jelly (RJ) has been reported to possess several physiological and pharmacological properties such as the ability to prevent osteoporosis in rats and anti-inflammatory effects. We hypothesized that RJ could have beneficial effects on the prevention or treatment of periodontal diseases, which are chronic inflammatory diseases caused by bacterial infection that result in resorption of the tooth-supporting bone. We assessed the effect of RJ on mineralization in mouse periodontal ligament cell clone 22 (MPDL22 cells), which are of an osteogenic and cementogenic lineage. The mRNA expression of osteopontin, osteocalcin and osterix, and mineralized nodule formation were significantly enhanced in RJ-treated MPDL22 cells. In addition, we investigated the effects of RJ on the production of inflammatory cytokines from MPDL22 cells stimulated with lipopolysaccharide (LPS) of Porphyromonas gingivalis, a periodontopathic bacterium. RJ suppressed LPS-induced interleukin-6 and CXC chemokine ligand 10 production from MPDL22 cells. Furthermore, RJ suppressed the expression of CD54 in MPDL22 cells: CD54 is the adhesion molecule involved in the accumulation of leukocytes in periodontal lesions. These findings suggest that the osteoinductive and anti-inflammatory effects of RJ can provide benefits for the treatment and prevention of periodontal diseases.