C-reactive protein (CRP) up-regulates expression of receptor for advanced glycation end products (RAGE) and its inflammatory ligand EN-RAGE in THP-1 cells: Inhibitory effects of atorvastatin

Background: Receptor for advanced glycation end products (RAGE) may play an important role in inflammatory processes and endothelial activation. Extracellular newly identified RAGE binding protein (EN-RAGE), natural pro-inflammatory ligand for RAGE. The role of C-reactive protein (CRP) as a mediator in inflammation and atherosclerosis is the subject of recent investigations worldwide. In the present study, we investigated the effect of CRP on RAGE and EN-RAGE gene expression in THP-1 monocytic cell line. MAP kinases (ERK, p38 and JNK) were exploited as possible signaling pathways involved in the signal transduction by CRP. Further, atorvastatin was used as a therapeutic modality for modulation of these genes in the presence of CRP. Materials and methods: Time and dose-dependent experiments were carried out in the presence of CRP. Specific MAPK pathways inhibitors were used to elucidate the signaling pathways involved. Effect of atorvastatin was also determined in the presence of CRP on the expression of these genes. Results: Time and dose-dependent experiments revealed that, treatment of THP-1 cells with 100 mu g of CRP/ml/10(6) cells for 24 h, augmented the expression of RAGE and EN-RAGE genes by 2.5-3.5 folds and 3.5-4.5 folds respectively. CRP acted via Fc gamma RII and utilized ERK, p38 and JNK pathways to transduce signals. Atorvastatin in a dose of 20 mu M, was able to attenuate up-regulation of CRP-induced genes (p<0.01) and effects were both dose and time-dependent. Conclusion: Our data strongly suggests that blockade of RAGE-EN-RAGE by statins at an early stage may prevent inflammation in atherosclerosis and counteract the harmful effects mediated by CRP. (C) 2009 Elsevier Ireland Ltd. All rights reserved.