title: Macrophage migration inhibitory factor promotes innate immune responses by suppressing glucocorticoid-induced expression of mitogen-activated protein kinase phosphatase-1.
abstract: The pro-inflammatory cytokine macrophage migration inhibitory factor (MIF) acts as a physiological counter-regulator of the immuno-suppressive effects of glucocorticoids. However, the mechanisms whereby MIF exerts its counter-balancing effect remain largely unknown. Here we report that MAPK phosphatase 1 (MKP-1), an archetypal member of dual specificity phosphatase that inactivates MAPK activity in response to pro-inflammatory stimuli, is a critical target of MIF-glucocorticoid crosstalk. Recombinant MIF counter-regulated in a dose-dependent fashion dexamethasone inhibition of TNF and IL-8 production by RAW 264.7 macrophages and U-937 promonocytes stimulated with lipopolysaccharides (LPS) or with LPS plus phorbol 12-myristate 13-acetate. Stimulation of RAW 264.7 macrophages with dexamethasone or dexamethasone plus LPS led to a robust up-regulation of MKP-1 mRNA and protein expressions that were counter-regulated by addition of recombinant MIF. Antisense MIF macrophages expressing reduced levels of endogenous MIF produced higher amount of MKP-1 and lower amount of TNF after exposure to dexamethasone and dexamethasone plus LPS, indicating that endogenous MIF acts in an autocrine fashion to override glucocorticoid-induced MKP-1 expression and inhibition of cytokine production. Taken together, these data identify MKP-1 as a molecular target of MIF-glucocorticoid crosstalk and provide a molecular basis for the control of macrophage responses by a pair of physiological regulators of innate immunity.
authors.affiliation: Infectious Diseases Service, Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. Thierry.Calandra@chuv.ch
authors.forename: Thierry
authors.initials: T
authors.lastname: Roger
authors.forename: Anne-Laure
authors.initials: AL
authors.lastname: Chanson
authors.forename: Marlies
authors.initials: M
authors.lastname: Knaup-Reymond
authors.forename: Thierry
authors.initials: T
authors.lastname: Calandra
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics*; D002460:Cell Line; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D054638:Dual Specificity Phosphatase 1; D005938:Glucocorticoids / Q000037:antagonists & inhibitors / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics*; D007113:Immunity, Innate; D008263:Macrophage Migration-Inhibitory Factors / Q000502:physiology*; D051379:Mice; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics*; D054645:Protein Phosphatase 1; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics*; D020298:U937 Cells
chemical_list: D018797:Cell Cycle Proteins; D016207:Cytokines; D005938:Glucocorticoids; D017874:Immediate-Early Proteins; D008263:Macrophage Migration-Inhibitory Factors; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; C517019:DUSP1 protein, human; D054638:Dual Specificity Phosphatase 1; C517020:Dusp1 protein, mouse; D017027:Protein Tyrosine Phosphatases