Ongoing Dll4-Notch signaling is required for T-cell homeostasis in the adult thymus

Eur J Immunol. 2011 Aug;41(8):2207-16. doi: 10.1002/eji.201041343. Epub 2011 Jul 4.

Abstract

The essential role of the Delta-like ligand 4 (Dll4)-Notch signaling pathway in T-lymphocyte development is well established. It has been shown that specific inactivation of Dll4 on thymic stromal cells during early post-natal development leads to a deregulation in T-cell differentiation. However, whether ongoing Dll4-Notch signaling is required for T-cell development in the adult thymus is unknown. The use of anti-Dll4 Abs allowed us to confirm and expand previous studies by examining the kinetics and the reversibility of Dll4-Notch signaling blockade in T-cell development in adult mice. We found that anti-Dll4 treatment reduced thymic cellularity after 7 days, as a consequence of a developmental delay in T-cell maturation at the pro-T-cell double negative 1 (CD4(-) CD8(-) c-kit(+) CD44(+) CD25(-) ) stage, leading to decreased numbers of immature double-positive (CD4(+) CD8(+) ) T cells without affecting the frequency of mature single positive CD4(+) and CD8(+) thymocytes, while promoting alternative thymic B-cell expansion. This cellular phenotype was similarly observed in both young adult and aged mice (>1.5 years), extending our understanding of the ongoing role for Dll4-Notch signaling during T-cell development in the adult thymus. Finally, after cessation of Dll4 Ab treatment, thymic cellularity and thymocyte subset ratios returned to normal levels, indicating reversibility of this phenotype in both adult and aged mice, which has important implications for potential clinical use of Dll4-Notch inhibitors.

MeSH terms

  • Age Factors
  • Animals
  • Antibodies / immunology
  • Antibodies / pharmacology
  • Atrophy / immunology
  • B-Lymphocytes / immunology
  • B-Lymphocytes / metabolism
  • Calcium-Binding Proteins
  • Cell Differentiation / drug effects
  • Cell Differentiation / immunology
  • Flow Cytometry
  • Gene Expression Profiling
  • Homeostasis / immunology
  • Humans
  • Immunohistochemistry
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / immunology*
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / immunology*
  • Membrane Proteins / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Oligonucleotide Array Sequence Analysis
  • Receptors, Notch / genetics
  • Receptors, Notch / immunology*
  • Receptors, Notch / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / drug effects
  • Signal Transduction / immunology*
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism
  • Thymus Gland / immunology*
  • Thymus Gland / metabolism
  • Thymus Gland / pathology
  • Time Factors

Substances

  • Antibodies
  • Calcium-Binding Proteins
  • DLL4 protein, mouse
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • Receptors, Notch