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

The receptor activator of NF-kappa B ligand (RANKL) and its signal downstream nuclear factor-KB (NF-kappa B) 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-kappa B expression, proliferation and apoptosis of human Jurkat T cells. Jurkat T cells were pretreated with 100 pmol/l tumor necrosis factor-alpha (TNF-alpha) for 1 h followed by various concentrations of EM for 24 h. The mRNA expressions of RANKL and NF-kappa B were examined by RT-PCR. The protein expression of NF-kappa B 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-alpha-induced expressions of RANKL and NF-kappa B at both mRNA and protein levels in a concentration-dependent manner. The expression of RANKL was correlated with the expression of NF-kappa B. Moreover, EM influenced the proliferation and apoplosis 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-kappa B and the proliferation of human Jurkat T cells, but also to reduce the level of RANKL. (C) 2009 Elsevier B.V. All rights reserved.