Itk-mediated integration of T cell receptor and cytokine signaling regulates the balance between Th17 and regulatory T cells

J Exp Med. 2014 Mar 10;211(3):529-43. doi: 10.1084/jem.20131459. Epub 2014 Feb 17.

Abstract

A proper balance between Th17 and T regulatory cells (Treg cells) is critical for generating protective immune responses while minimizing autoimmunity. We show that the Tec family kinase Itk (IL2-inducible T cell kinase), a component of T cell receptor (TCR) signaling pathways, influences this balance by regulating cross talk between TCR and cytokine signaling. Under both Th17 and Treg cell differentiation conditions, Itk(-/-) CD4(+) T cells develop higher percentages of functional FoxP3(+) cells, associated with increased sensitivity to IL-2. Itk(-/-) CD4(+) T cells also preferentially develop into Treg cells in vivo. We find that Itk-deficient T cells exhibit reduced TCR-induced phosphorylation of mammalian target of rapamycin (mTOR) targets, accompanied by downstream metabolic alterations. Surprisingly, Itk(-/-) cells also exhibit reduced IL-2-induced mTOR activation, despite increased STAT5 phosphorylation. We demonstrate that in wild-type CD4(+) T cells, TCR stimulation leads to a dose-dependent repression of Pten. However, at low TCR stimulation or in the absence of Itk, Pten is not effectively repressed, thereby uncoupling STAT5 phosphorylation and phosphoinositide-3-kinase (PI3K) pathways. Moreover, Itk-deficient CD4(+) T cells show impaired TCR-mediated induction of Myc and miR-19b, known repressors of Pten. Our results demonstrate that Itk helps orchestrate positive feedback loops integrating multiple T cell signaling pathways, suggesting Itk as a potential target for altering the balance between Th17 and Treg cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Cell Differentiation / immunology
  • Cytokines / metabolism*
  • DNA-Binding Proteins / genetics
  • Flow Cytometry
  • Genetic Vectors / genetics
  • Immunity, Cellular / immunology*
  • Immunoblotting
  • Mice
  • Mice, Knockout
  • Mice, Transgenic
  • Oligonucleotides / genetics
  • PTEN Phosphohydrolase / metabolism
  • Protein-Tyrosine Kinases / genetics
  • Protein-Tyrosine Kinases / immunology*
  • Protein-Tyrosine Kinases / metabolism
  • Receptor Cross-Talk / immunology
  • Receptors, Antigen, T-Cell / metabolism*
  • Retroviridae
  • Reverse Transcriptase Polymerase Chain Reaction
  • STAT5 Transcription Factor / metabolism
  • Signal Transduction / immunology*
  • T-Lymphocytes, Regulatory / immunology*
  • Th17 Cells / immunology*

Substances

  • Cytokines
  • DNA-Binding Proteins
  • Oligonucleotides
  • Rag2 protein, mouse
  • Receptors, Antigen, T-Cell
  • STAT5 Transcription Factor
  • Protein-Tyrosine Kinases
  • emt protein-tyrosine kinase
  • PTEN Phosphohydrolase
  • Pten protein, mouse