Abstract
Delta-like ligand 4 (Dll4)-Notch signaling is essential for T cell development and alternative thymic lineage decisions. How Dll4-Notch signaling affects pro-T cell fate and thymic dendritic cell (tDC) development is unknown. We found that Dll4 pharmacological blockade induces accumulation of tDCs and CD4(+)CD25(+)FoxP3(+) regulatory T cells (T(reg) cells) in the thymic cortex. Both genetic inactivation models and anti-Dll4 antibody (Ab) treatment promote de novo natural T(reg) cell expansion by a DC-dependent mechanism that requires major histocompatibility complex II expression on DCs. Anti-Dll4 treatment converts CD4(-)CD8(-)c-kit(+)CD44(+)CD25(-) (DN1) T cell progenitors to immature DCs that induce ex vivo differentiation of naive CD4(+) T cells into T(reg) cells. Induction of these tolerogenic DN1-derived tDCs and the ensuing expansion of T(reg) cells are Fms-like tyrosine kinase 3 (Flt3) independent, occur in the context of transcriptional up-regulation of PU.1, Irf-4, Irf-8, and CSF-1, genes critical for DC differentiation, and are abrogated in thymectomized mice. Anti-Dll4 treatment fully prevents type 1 diabetes (T1D) via a T(reg) cell-mediated mechanism and inhibits CD8(+) T cell pancreatic islet infiltration. Furthermore, a single injection of anti-Dll4 Ab reverses established T1D. Disease remission and recurrence are correlated with increased T(reg) cell numbers in the pancreas-draining lymph nodes. These results identify Dll4-Notch as a novel Flt3-alternative pathway important for regulating tDC-mediated T(reg) cell homeostasis and autoimmunity.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing
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Amyloid Precursor Protein Secretases / deficiency
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Amyloid Precursor Protein Secretases / metabolism
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Animals
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Antibodies / pharmacology
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Blotting, Western
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Calcium-Binding Proteins
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Cell Differentiation / immunology*
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DNA Primers / genetics
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Dendritic Cells / immunology
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Dendritic Cells / physiology*
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Diabetes Mellitus, Type 1 / immunology
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Diabetes Mellitus, Type 1 / prevention & control*
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Enzyme-Linked Immunosorbent Assay
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Flow Cytometry
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Fluorescent Antibody Technique
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Genes, MHC Class II / immunology
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Intracellular Signaling Peptides and Proteins / immunology
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Intracellular Signaling Peptides and Proteins / metabolism*
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Membrane Glycoproteins / deficiency
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Membrane Glycoproteins / metabolism
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Membrane Proteins / immunology
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Membrane Proteins / metabolism*
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Mice
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Mice, Inbred C57BL
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Mice, Inbred NOD
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Mice, Transgenic
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Microscopy, Confocal
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Oligonucleotide Array Sequence Analysis
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Pancreas / pathology
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Polymerase Chain Reaction
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Receptors, Notch / metabolism*
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Signal Transduction / immunology
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Signal Transduction / physiology*
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T-Lymphocyte Subsets / immunology
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Thymus Gland / cytology
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Thymus Gland / immunology
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fms-Like Tyrosine Kinase 3 / genetics
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fms-Like Tyrosine Kinase 3 / metabolism
Substances
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Adaptor Proteins, Signal Transducing
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Antibodies
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Calcium-Binding Proteins
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DLL4 protein, mouse
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DNA Primers
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Intracellular Signaling Peptides and Proteins
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Membrane Glycoproteins
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Membrane Proteins
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Receptors, Notch
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nicastrin protein
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Flt3 protein, mouse
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fms-Like Tyrosine Kinase 3
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Amyloid Precursor Protein Secretases