A key role for IL‐7R in the generation of microenvironments required for thymic dendritic cells

Interleukin‐7 receptor (IL‐7R) signaling is critical for multiple stages of T‐cell development, but a role in the establishment of the mature thymic architecture needed for T‐cell development and thymocyte selection has not been established. Crosstalk signals between developing thymocytes and thymic...

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Bibliographic Details
Published in:Immunology and cell biology 2017-11, Vol.95 (10), p.933-942
Main Authors: Moore, Amanda J, In, Tracy SH, Trotman‐Grant, Ashton, Yoganathan, Kogulan, Montpellier, Bertrand, Guidos, Cynthia J, Zúñiga‐Pflücker, Juan Carlos, Anderson, Michele K
Format: Article
Language:English
Subjects:
Animals
Bone marrow
CC chemokine receptors
CCR7 protein
Cell Differentiation
Cells, Cultured
Cellular Microenvironment
Chemokine CXCL12 - metabolism
Chemokines
Chemokines, CC - metabolism
Chimeras
CXCL12 protein
Dendritic cells
Dendritic Cells - physiology
Epithelial cells
Epithelial Cells - physiology
Interleukin 7
Interleukin 7 receptors
Lymphocytes T
Mice
Mice, Inbred C57BL
Mice, Knockout
Microenvironments
Original
Osteoprogenitor cells
Phenotypes
Receptors, CCR7 - metabolism
Receptors, Interleukin-7 - genetics
Receptors, Interleukin-7 - metabolism
Spleen
T-Lymphocytes - physiology
Thymocytes
Thymus
Thymus Gland - immunology
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Summary:Interleukin‐7 receptor (IL‐7R) signaling is critical for multiple stages of T‐cell development, but a role in the establishment of the mature thymic architecture needed for T‐cell development and thymocyte selection has not been established. Crosstalk signals between developing thymocytes and thymic epithelial cell (TEC) precursors are critical for their differentiation into cortical TECs (cTECs) and medullary TECs (mTECs). In addition, mTEC‐derived factors have been implicated in the recruitment of thymic dendritic cells (DCs) and intrathymic DC development. We therefore examined corticomedullary structure and DC populations in the thymus of Il7r−/− mice. Analysis of TEC phenotype and spatial organization revealed a striking shift in the mTEC to cTEC ratio, accompanied by disorganized corticomedullary structure. Several of the thymic subsets known to have DC potential were nearly absent, accompanied by reductions in DC cell numbers. We also examined chemokine expression in the Il7r−/− thymus, and found a significant decrease in mTEC‐derived CCR7 ligand expression, and high levels of cTEC‐derived chemokines, including CCL25 and CXCL12. Although splenic DCs were similarly affected, bone marrow (BM) precursors capable of giving rise to DCs were unperturbed. Finally, BM chimeras showed that there was no intrinsic need for IL‐7R signaling in the development or recruitment of thymic DCs, but that the provision of wild‐type progenitors enhanced reconstitution of thymic DCs from Il7r−/− progenitors. Our results are therefore supportive of a model in which Il7r‐dependent cells are required to set up the microenvironments that allow accumulation of thymic DCs.
ISSN:0818-9641
1440-1711
DOI:10.1038/icb.2017.74