title: Adenosine 5'-monophosphate-activated protein kinase regulates IL-10-mediated anti-inflammatory signaling pathways in macrophages.
abstract: AMP-activated protein kinase (AMPK) is a conserved serine/threonine kinase with a critical function in the regulation of metabolic pathways in eukaryotic cells. Recently, AMPK has been shown to play an additional role as a regulator of inflammatory activity in leukocytes. Treatment of macrophages with chemical AMPK activators, or forced expression of a constitutively active form of AMPK, results in polarization to an anti-inflammatory phenotype. In addition, we reported previously that stimulation of macrophages with anti-inflammatory cytokines such as IL-10, IL-4, and TGF-β results in rapid activation of AMPK, suggesting that AMPK contributes to the suppressive function of these cytokines. In this study, we investigated the role of AMPK in IL-10-induced gene expression and anti-inflammatory function. IL-10-stimulated wild-type macrophages displayed rapid activation of PI3K and its downstream targets Akt and mammalian target of rapamycin complex (mTORC1), an effect that was not seen in macrophages generated from AMPKα1-deficient mice. AMPK activation was not impacted by treatment with either the PI3K inhibitor LY294002 or the JAK inhibitor CP-690550, suggesting that IL-10-mediated activation of AMPK is independent of PI3K and JAK activity. IL-10 induced phosphorylation of both Tyr(705) and Ser(727) residues of STAT3 in an AMPKα1-dependent manner, and these phosphorylation events were blocked by inhibition of Ca(2+)/calmodulin-dependent protein kinase kinase β, an upstream activator of AMPK, and by the mTORC1 inhibitor rapamycin, respectively. The impaired STAT3 phosphorylation in response to IL-10 observed in AMPKα1-deficient macrophages was accompanied by reduced suppressor of cytokine signaling 3 expression and an inadequacy of IL-10 to suppress LPS-induced proinflammatory cytokine production. Overall, our data demonstrate that AMPKα1 is required for IL-10 activation of the PI3K/Akt/mTORC1 and STAT3-mediated anti-inflammatory pathways regulating macrophage functional polarization.
authors.affiliation: Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40292.
authors.forename: Yanfang Peipei
authors.initials: YP
authors.lastname: Zhu
authors.affiliation: Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40292.
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Brown
authors.affiliation: Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40292.
authors.forename: Duygu
authors.initials: D
authors.lastname: Sag
authors.affiliation: Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40292.
authors.forename: Lihua
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Microbiology and Immunology, University of Louisville School of Medicine, Louisville, KY 40292 jill.suttles@louisville.edu.
authors.forename: Jill
authors.initials: J
authors.lastname: Suttles
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000276:immunology*; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D007249:Inflammation / Q000139:chemically induced / Q000235:genetics / Q000276:immunology / Q000473:pathology; D016753:Interleukin-10 / Q000235:genetics / Q000276:immunology*; D015847:Interleukin-4 / Q000235:genetics / Q000276:immunology; D008070:Lipopolysaccharides / Q000633:toxicity; D008264:Macrophages / Q000276:immunology* / Q000473:pathology; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D018345:Mice, Knockout; D046912:Multiprotein Complexes / Q000235:genetics / Q000276:immunology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000276:immunology; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000276:immunology; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000276:immunology; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000276:immunology
chemical_list: D055372:AMP-Activated Protein Kinases; D016753:Interleukin-10; D015847:Interleukin-4; D008070:Lipopolysaccharides; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D050796:STAT3 Transcription Factor; D058570:TOR Serine-Threonine Kinases; D016212:Transforming Growth Factor beta; C556062:IL10 protein, mouse; C494087:Stat3 protein, mouse; C548179:Prkaa1 protein, mouse