The upregulation of receptor activator NF-κB ligand expression by interleukin-1α and Porphyromonas endodontalis in human osteoblastic cells


Dr Yu-Chao Chang DDS. MMS. PhD, Professor, School of Dentistry, Chung Shan Medical University, 110, Sec. 1, Chien-Kuo N. Rd., Taichung, Taiwan (Tel.: 886 4 22015111: fax: 886 4 24759065;


Aim  To investigate the receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL) in osteoblastic cells stimulated with inflammatory mediators.

Methodology  The expression of RANKL in human osteoblastic cell line U2OS stimulated by pro-inflammatory cytokine interleukin (IL)-1α and black-pigmented bacteria Porphyromonas endodontalis was investigated by Western blot and enzyme-linked immunosorbent assay (ELISA). The significance of the results obtained from control and treated groups was statistically analysed by the paired Student’s t-test.

Results  IL-1α was found to upregulate RANKL production in U2OS cells (P < 0.05). Investigations of the time dependence of RANKL expression in IL-1α-treated cells revealed a rapid accumulation of RANKL protein after 1 h of exposure; it remained elevated throughout the 24-h incubation period shown by Western blot and ELISA. In addition, P. endodontalis also increased RANKL expression in U2OS cells after 4-h incubation period demonstrated by Western blot and ELISA (P < 0.05).

Conclusions  IL-1α and P. endodontalis may be involved in developing apical periodontitis through the stimulation of RANKL production.