Activation of a TGF-β-specific multistep gene expression program in mature macrophages requires glucocorticoid-mediated surface expression of TGF-β receptor II

A Gratchev, J Kzhyshkowska… - The Journal of …, 2008 - journals.aai.org
A Gratchev, J Kzhyshkowska, S Kannookadan, M Ochsenreiter, A Popova, X Yu, S Mamidi…
The Journal of Immunology, 2008journals.aai.org
Alternatively activated (M2) macrophages regulate steady state-, cancer-, and inflammation-
related tissue remodeling. They are induced by Th2-cytokines and glucocorticoids (GC). The
responsiveness of mature macrophages to TGF-β, a cytokine involved in inflammation,
cancer, and atherosclerosis, is currently controversial. Recently, we demonstrated that IL-17
receptor B is up-regulated in human monocyte-derived macrophages differentiated in the
presence of Th2 cytokines IL-4 and TGF-β1. In this study, we show that mature human …
Abstract
Alternatively activated (M2) macrophages regulate steady state-, cancer-, and inflammation-related tissue remodeling. They are induced by Th2-cytokines and glucocorticoids (GC). The responsiveness of mature macrophages to TGF-β, a cytokine involved in inflammation, cancer, and atherosclerosis, is currently controversial. Recently, we demonstrated that IL-17 receptor B is up-regulated in human monocyte-derived macrophages differentiated in the presence of Th2 cytokines IL-4 and TGF-β1. In this study, we show that mature human macrophages differentiated in the presence of IL-4, and dexamethasone (M2 IL-4/GC) but not M2 IL-4 responds to TGF-β1 which induced a gene expression program comprising 111 genes including transcriptional/signaling regulators (ID3 and RGS1), immune modulators (ALOX5AP and IL-17 receptor B) and atherosclerosis-related genes (ALOX5AP, ORL1, APOC1, APOC2, and APOE). Analysis of molecular mechanism underlying GC/TGF-β cooperation revealed that surface expression of TGF-βRII was high in M2 GC and M2 IL-4/GC, but absent from M2 IL-4, whereas the expression of TGF-βRI/II mRNA, TGF-βRII total protein, and surface expression of TGF-βRIII were unchanged. GC dexamethasone was essential for increased surface expression of functional TGF-βRII because its effect was observed also in combination with IL-13, M-CSF, and GM-CSF. Prolonged Smad2-mediated signaling observed in TGF-β1-treated M2 IL-4/GC was due to insufficient activity of negative feedback mechanism what can be explained by up-regulation of SIRT1, a negative regulator of Smad7, and the retention of TGF-βRII complex on the cell surface. In summary, mature human M2 macrophages made permissive to TGF-β by GC-induced surface expression of TGF-βRII activate in response to TGF-β1, a multistep gene expression program featuring traits of macrophages found within an atherosclerotic lesion.
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