Abstract
BackgroundCompound A (CpdA) is a dissociating non-steroidal glucocorticoid receptor (GR) ligand which has anti-inflammatory properties exerted by down-modulating proinflammatory gene expression. By favouring GR monomer formation, CpdA does not enhance glucocorticoid (GC) response element-driven gene expression, resulting in a reduced side effect profile as compared to GCs. Considering the importance of Th1/Th2 balance in the final outcome of immune and inflammatory responses, we analyzed how selective GR modulation differentially regulates the activity of T-bet and GATA-3, master drivers of Th1 and Th2 differentiation, respectively.ResultsUsing Western analysis and reporter gene assays, we show in murine T cells that, similar to GCs, CpdA inhibits T-bet activity via a transrepressive mechanism. Different from GCs, CpdA induces GATA-3 activity by p38 MAPK-induction of GATA-3 phosphorylation and nuclear translocation. CpdA effects are reversed by the GR antagonist RU38486, proving the involvement of GR in these actions. ELISA assays demonstrate that modulation of T-bet and GATA-3 impacts on cytokine production shown by a decrease in IFN-γ and an increase in IL-5 production, respectively.ConclusionsTaken together, through their effect favoring Th2 over Th1 responses, particular dissociated GR ligands, for which CpdA represents a paradigm, hold potential for the application in Th1-mediated immune disorders.
Highlights
Glucocorticoids (GCs) are the most potent and frequently used anti-inflammatory drugs for a variety of Th1- and Th2-mediated immune disorders
It is widely accepted that the desired anti-inflammatory effects of GCs are caused by the interaction of the monomeric glucocorticoid receptor (GR) with the activity of other transcription factor (TF) that drive proinflammatory gene expression, whereas the direct binding of GR to GC response elements (GREs) resulting in the direct transcription of target genes is mostly associated with well-known endocrine side effects [2]
Transfection of EL4 T cells with T box expressed in T cells (T-bet) response elements cloned upstream of the luciferase gene (T-bet-RE-Luc) together with GR (CMV-hGR) and T-bet expression vectors in the presence of increasing amounts of Compound A (CpdA) led to a dose-dependent inhibition of T-bet’s transcriptional activity (Fig. 1A), similar to the effect we have previously reported for GCs (Fig. 1A, striped bar) [26]
Summary
Glucocorticoids (GCs) are the most potent and frequently used anti-inflammatory drugs for a variety of Th1- and Th2-mediated immune disorders. It is widely accepted that the desired anti-inflammatory effects of GCs are caused by the interaction of the monomeric GR with the activity of other TFs that drive proinflammatory gene expression, whereas the direct binding of GR to GC response elements (GREs) resulting in the direct transcription of target genes is mostly associated with well-known endocrine side effects [2]. This has led to the search for selective GR modulators, such as dissociated GR ligands, that selectively transrepress and which are predicted to reduce the appearance of a wide range of side effects. Considering the importance of Th1/Th2 balance in the final outcome of immune and inflammatory responses, we analyzed how selective GR modulation differentially regulates the activity of T-bet and GATA-3, master drivers of Th1 and Th2 differentiation, respectively
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