The production of receptor activator of NF-kB ligand and osteoprotegerin in culture supernatant of human periodontal ligament cells stimulated with E. coli LPS

Objective To examine the production of receptor activator of NF-kB ligand(RANKL) and osteoprotegerin(OPG) in the culture supernatant of human periodontal ligament cells after stimulation with E.coli lipopolysaccharide(LPS),and to elucidate the role of periodontal ligament cells in alveolar bone resorption.Methods Primary human periodontal ligament cells were cultured and identified immunologically.The fourth passage of the cells was stimulated with E coli.LPS for 0h,4h,8h,12h,and 24h,enzyme linked immunosorbent assay(ELISA)was used to examine the concentration of secreted RANKL and OPG in the supernatant.Results After stimulation with LPS,OPG concentration in the supernatant exhibited no significant change,but RANKL concentration in the stimulated groups increased gradually from 4h,and peaked at 24h,statistic analysis revealed significant difference for all the stimulated groups when compared with the control groups(P 0.01);within stimulated groups,8h and 12h also revealed a significant difference(P0.05);Groups without LPS stimulation exhibited a low level of RANKL and OPG,and had no significant changes at any of the time points examined.Conclusion Periodontal ligament cells stimulated with LPS expressed an increased level of RANKL,but OPG expression have no significant change.