In vitro effects of erythromycin on RANKL and nuclear factor-kappa B by human TNF-α stimulated Jurkat cells

The receptor activator of NF-κB ligand (RANKL) and its signal downstream nuclear factor-κB (NF-κB) are critical regulators for immune responses as well as bone remodeling. The present study aimed to examine the effects of erythromycin (EM) on the activation of RANKL, correlation with NF-κB expression, proliferation and apoptosis of human Jurkat T cells. Jurkat T cells were pretreated with 100 pmol/l tumor necrosis factor-alpha (TNF-α) for 1 h followed by various concentrations of EM for 24 h. The mRNA expressions of RANKL and NF-κB were examined by RT-PCR. The protein expression of NF-κB was analyzed by Western blot. The protein level of RANKL was examined by flow cytometry, immunofluorescence microscopy and Western blot analyses. We also examined proliferation of Jurkat T cells by MTT assay, apoptosis by flow cytometry analysis after staining with PI and morphological observation after AO/EB staining. The results showed that EM inhibited TNF-α-induced expressions of RANKL and NF-κB at both mRNA and protein levels in a concentration-dependent manner. The expression of RANKL was correlated with the expression of NF-κB. Moreover, EM influenced the proliferation and apoptosis of human Jurkat T cells. These data suggest that EM acts as an anti-inflammatory agent not only to interact with the expression of NF-κB and the proliferation of human Jurkat T cells, but also to reduce the level of RANKL.