Redefining thymus medulla specialization for central tolerance

J Exp Med. 2017 Nov 6;214(11):3183-3195. doi: 10.1084/jem.20171000. Epub 2017 Aug 22.

Abstract

During αβT cell development, the thymus medulla represents an essential microenvironment for T cell tolerance. This functional specialization is attributed to its typical organized topology consisting of a branching structure that contains medullary thymic epithelial cell (mTEC) networks to support negative selection and Foxp3+ T-regulatory cell (T-reg) development. Here, by performing TEC-specific deletion of the thymus medulla regulator lymphotoxin β receptor (LTβR), we show that thymic tolerance mechanisms operate independently of LTβR-mediated mTEC development and organization. Consistent with this, mTECs continue to express Fezf2 and Aire, regulators of intrathymic self-antigens, and support T-reg development despite loss of LTβR-mediated medulla organogenesis. Moreover, we demonstrate that LTβR controls thymic tolerance by regulating the frequency and makeup of intrathymic dendritic cells (DCs) required for effective thymocyte negative selection. In all, our study demonstrates that thymus medulla specialization for thymic tolerance segregates from medulla organogenesis and instead involves LTβR-mediated regulation of the thymic DC pool.

MeSH terms

  • Animals
  • Autoantigens / immunology
  • Central Tolerance / genetics
  • Central Tolerance / immunology*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / immunology
  • DNA-Binding Proteins / metabolism
  • Dendritic Cells / immunology
  • Dendritic Cells / metabolism
  • Epithelial Cells / immunology*
  • Epithelial Cells / metabolism
  • Forkhead Transcription Factors / immunology
  • Forkhead Transcription Factors / metabolism
  • Lymphotoxin beta Receptor / genetics
  • Lymphotoxin beta Receptor / immunology*
  • Lymphotoxin beta Receptor / metabolism
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Microscopy, Confocal
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / immunology
  • Nerve Tissue Proteins / metabolism
  • Organogenesis / immunology
  • Reverse Transcriptase Polymerase Chain Reaction
  • T-Lymphocytes, Regulatory / immunology
  • T-Lymphocytes, Regulatory / metabolism
  • Thymus Gland / embryology
  • Thymus Gland / immunology*
  • Thymus Gland / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / immunology
  • Transcription Factors / metabolism

Substances

  • APECED protein
  • Autoantigens
  • DNA-Binding Proteins
  • Forkhead Transcription Factors
  • Foxp3 protein, mouse
  • Lymphotoxin beta Receptor
  • Nerve Tissue Proteins
  • Transcription Factors
  • Zfp312 protein, mouse