Effects of HSP70 on the compression force-induced TNF-α and RANKL expression in human periodontal ligament cells

Abstract

The aim of this study was to investigate the effect of heat shock protein 70 (HSP70) on the mRNA expression of tumor necrosis factor-alpha (TNF-α) and receptor activator of nuclear factor-kappa B ligand (RANKL) induced by compressive forces (CF) in human periodontal ligament (hPDL) cells. hPDL cells were subjected to 1.0, 2.0, or 4.0 g/cm(2) of CF for 24 h, and were treated with recombinant human inducible HSP70 for 12 h. The mRNA expression of HSP27, HSP70, HSP90, TNF-α, RANKL and OPG from hPDL cells subjected to CF was determined by real-time PCR. The protein production of HSP70 was determined by Western blot analysis and ELISA. The mRNA expression of HSP70, TNF-α and RANKL were found to be increased in a time- and magnitude-dependent manner, detectable at 12, 9, and 9 h, respectively. TNF-α and RANKL expression gradually decreased at 12 h with increasing HSP70 levels, and further decreased thereafter. Furthermore, exogenous HSP70 partially inhibited the CF-induced TNF-α and RANKL expression in a dose-dependent manner at 6 and 12 h. These results indicate that HSP70 may modulate the mRNA expression of TNF-α and RANKL in hPDL cells in response to CF.