The MAPK-Activated Kinase MK2 Attenuates Dendritic Cell-Mediated Th1 Differentiation and Autoimmune Encephalomyelitis

J Immunol. 2015 Jul 15;195(2):541-52. doi: 10.4049/jimmunol.1401663. Epub 2015 Jun 15.

Abstract

Dendritic cell (DC)-mediated inflammation induced via TLRs is promoted by MAPK-activated protein kinase (MK)-2, a substrate of p38 MAPK. In this study we show an opposing role of MK2, by which it consolidates immune regulatory functions in DCs through modulation of p38, ERK1/2-MAPK, and STAT3 signaling. During primary TLR/p38 signaling, MK2 mediates the inhibition of p38 activation and positively cross-regulates ERK1/2 activity, leading to a reduction of IL-12 and IL-1α/β secretion. Consequently, MK2 impairs secondary autocrine IL-1α signaling in DCs, which further decreases the IL-1α/p38 but increases the anti-inflammatory IL-10/STAT3 signaling route. Therefore, the blockade of MK2 activity enables human and murine DCs to strengthen proinflammatory effector mechanisms by promoting IL-1α-mediated Th1 effector functions in vitro. Furthermore, MK2-deficient DCs trigger Th1 differentiation and Ag-specific cytotoxicity in vivo. Finally, wild-type mice immunized with LPS in the presence of an MK2 inhibitor strongly accumulate Th1 cells in their lymph nodes. These observations correlate with a severe clinical course in DC-specific MK2 knockout mice compared with wild-type littermates upon induction of experimental autoimmune encephalitis. Our data suggest that MK2 exerts a profound anti-inflammatory effect that prevents DCs from prolonging excessive Th1 effector T cell functions and autoimmunity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Differentiation
  • Dendritic Cells / drug effects
  • Dendritic Cells / immunology*
  • Dendritic Cells / pathology
  • Encephalomyelitis, Autoimmune, Experimental / genetics
  • Encephalomyelitis, Autoimmune, Experimental / immunology*
  • Encephalomyelitis, Autoimmune, Experimental / pathology
  • Gene Expression Regulation
  • Humans
  • Immunization
  • Interleukin-10 / genetics
  • Interleukin-10 / immunology
  • Interleukin-12 / genetics
  • Interleukin-12 / immunology
  • Interleukin-1alpha / genetics
  • Interleukin-1alpha / immunology
  • Interleukin-1beta / genetics
  • Interleukin-1beta / immunology
  • Intracellular Signaling Peptides and Proteins / antagonists & inhibitors
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / immunology*
  • Lipopolysaccharides / administration & dosage
  • Lipopolysaccharides / immunology
  • Lymph Nodes / drug effects
  • Lymph Nodes / immunology
  • Lymph Nodes / pathology
  • Male
  • Mice
  • Mice, Knockout
  • Mitogen-Activated Protein Kinase 1 / genetics
  • Mitogen-Activated Protein Kinase 1 / immunology
  • Mitogen-Activated Protein Kinase 3 / genetics
  • Mitogen-Activated Protein Kinase 3 / immunology
  • Protein Kinase Inhibitors / pharmacology
  • Protein Serine-Threonine Kinases / antagonists & inhibitors
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / immunology*
  • STAT3 Transcription Factor / genetics
  • STAT3 Transcription Factor / immunology
  • Signal Transduction
  • Th1 Cells / drug effects
  • Th1 Cells / immunology*
  • Th1 Cells / pathology
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / immunology

Substances

  • IL10 protein, mouse
  • Interleukin-1alpha
  • Interleukin-1beta
  • Intracellular Signaling Peptides and Proteins
  • Lipopolysaccharides
  • Protein Kinase Inhibitors
  • STAT3 Transcription Factor
  • Stat3 protein, mouse
  • Interleukin-10
  • Interleukin-12
  • MAP-kinase-activated kinase 2
  • Protein Serine-Threonine Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • p38 Mitogen-Activated Protein Kinases