Glucocorticoids mobilize macrophages by transcriptionally up-regulating the exopeptidase DPP4

David Diaz-Jimenez,Maria Grazia Petrillo,Jonathan T Busada,Marcela A Hermoso,John A Cidlowski

doi:10.1074/jbc.ra119.010894

Abstract

Glucocorticoids are potent endogenous anti-inflammatory molecules, and their cognate receptor, glucocorticoid receptor (GR), is expressed in nearly all immune cells. Macrophages are heterogeneous immune cells having a central role in both tissue homeostasis and inflammation and also play a role in the pathogenesis of some inflammatory diseases. Paradoxically, glucocorticoids have only a limited efficacy in controlling the resolution of these macrophage-related diseases. Here, we report that the transcriptomes of monocyte-like THP-1 cells and macrophage-like THP-1 cells (THP1-MΦ) have largely conserved gene expression patterns. In contrast, the differentiation to THP1-MΦ significantly altered the sensitivity of gene transcription to glucocorticoids. Among glucocorticoid-regulated genes, we identified the exopeptidase dipeptidyl peptidase-4 (DPP4) as a critical glucocorticoid-responsive gene in THP1-MΦ. We found that GR directly induces DPP4 gene expression by binding to two glucocorticoid-responsive elements (GREs) within the DPP4 promoter. Additionally, we show that glucocorticoid-induced DPP4 expression is blocked by the GR antagonist RU-486 and by GR siRNA transfection and that DPP4 enzyme activity is reduced by DPP4 inhibitors. Of note, glucocorticoids highly stimulated macrophage mobility; unexpectedly, DPP4 mediated the glucocorticoid-induced macrophage migration, and siRNA-mediated knockdowns of GR and DPP4 blocked dexamethasone-induced THP1-MΦ migration. Moreover, glucocorticoid-induced DPP4 activation was also observed in proinflammatory M1-polarized murine macrophages, as well as peritoneal macrophages, and was associated with increased macrophage migration. Our results indicate that glucocorticoids directly up-regulate DPP4 expression and thereby induce migration in macrophages, potentially explaining why glucocorticoid therapy is less effective in controlling macrophage-dominated inflammatory disorders.

Highlights

Glucocorticoids are potent endogenous anti-inflammatory molecules, and their cognate receptor, glucocorticoid receptor (GR), is expressed in most immune cells
We investigated whether the state of cell differentiation among monocytes and macrophages modifies the gene expression, with profiles of monocyte-like THP-1 cells (THP-1) and macrophage-like THP-1 cells (THP1-M⌽) analyzed by genome-wide microarray (Fig. S1)
A volcano plot comparing genes expressed in THP1-M⌽ with monocyte-like THP-1 cells revealed that the gene NR3C1/GR was highly expressed in THP1-M⌽ (Fig. 1B)

Summary

Introduction

Glucocorticoids are potent endogenous anti-inflammatory molecules, and their cognate receptor, glucocorticoid receptor (GR), is expressed in most immune cells. Glucocorticoid signaling in macrophages has been reported to up-regulate the expression of NLRP3 inflammasome component and to enhance the ATP-dependent secretion of cytokines such as TNF␣ and interleukin-6 [9] These findings suggest that glucocorticoids likely play a dual role regulating the innate and adaptive immune response differentially. These effects may depend on the type of inflammatory stimulus [10] and/or the timing of treatment [11], modulating the balance of the cellular state toward a net pro-inflammatory or anti-inflammatory state [7]. Macrophages may contribute to the pathophysiology of several diseases, including inflammatory disorders [20, 21], cancer [22], and states of low-grade inflammation such as obesity [23, 24]

Methods

Results

Conclusion