Differential effect of glucocorticoids on the activation of monocytes and macrophages

The Glucocorticoid receptor (GR/NR3C1) is expressed in almost all immune cells. Glucocorticoids (GCs) are potent regulators of inflammation with effects mainly immunosuppressive. While, GCs have pleiotropic effects on Macrophages exhibiting complex properties with enhancing as well as suppressive effects on inflammatory processes depending on their stage of differentiation and activation, the mechanisms of GCs actions on Monocytes and Macrophages and their contribution to systemic anti-inflammatory effects remain unclear. Previously we have demonstrated that NLRP3 expression is induced by GCs in macrophages differentiated from monocytes-THP-1 but not in monocytes. These findings raise the possibility that the stage of myeloid differentiation and the cellular environment dictates the actions of GR from a pro- or anti-inflammatory perspective. Moreover, our preliminary results using the same cell line THP-1 show that the differentiation process from monocytes to macrophages also is related with the downregulation of GR induced by dex. Human Monocyte cell line THP-1 was used for differentiation into macrophages with PMA during 3 hours and a time of recovery of 24 hours. Monocytes-THP-1 and macrophages-derived monocyte-THP-1 were maintained during 24 hours with charcoal medium before the Dex treatment for 6 hours. RNA samples from all treatments groups (Mono-THP-1 Vehicle and Dex and Macro-THP-1 vehicle and Dex) were extracted using QIAshredder and RNeasy Mini kit with DNase treatment. The RNA concentration will be determined by Nanodrop and the quality using BioAnalyzer. We expect to found significant differences in RNA expression between cells (Mono vs Macrophages) and treatment (Vehicle vs Dex).