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Abstract
The microenvironment of the thymus is composed of a group of stromal cells that include endoderm-derived thymic epithelial cells (TECs) and mesenchymal stromal cells such as fibroblasts and serves as a site for the development of T cells. TECs are known to play an essential role in T cell differentiation and selection. Mesenchymal stromal cells have been less studied in terms of their immunological significance compared to TECs. Recently, new technologies have made it possible to identify and characterize mesenchymal stromal cells in the thymus, revealing their unique functions in thymic organogenesis and T cell development. This review outlines the current views on mesenchymal stromal cells in the thymus, particularly highlighting the newly discovered function of thymic fibroblasts in T cell repertoire selection.
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Affiliation(s)
- Takeshi Nitta
- grid.26999.3d0000 0001 2151 536XDepartment of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
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2
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The unilateral involution in the thymus of a 96-year-old male leads to the preservation of structural integrity in one thymic lobe, as assessed by the expression of medullar and cortical antigens and the presence of CD3+ cells. Heliyon 2022; 8:e11734. [PMID: 36411931 PMCID: PMC9674545 DOI: 10.1016/j.heliyon.2022.e11734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/20/2022] [Accepted: 11/11/2022] [Indexed: 11/18/2022] Open
Abstract
The process of thymic involution begins soon after birth and continues through adult life. Although evolutionary conserved in all vertebrates, the thymic involution has no defined kinetics. Little is known about the pace of its regression in humans, except that there is a marked increase of thymic involution after puberty. This report describes the unusual structural findings in the thymus of a 96-year-old male. The morphological parameters of the organ were evaluated using H&E and immunohistochemistry (IHC) techniques. The macroscopic examination showed a typical organ's weight and size, except that the right thymic lobe presented a well-preserved organ and the left lobe was significantly adiposed. The H&E staining of the thymic sections from the left and right lobes confirmed advanced thymic adiposity in the left lobe and preserved thymic epithelial space containing hematoxylin-stained cells in the right lobe. The multiplex immunostaining of the right lobe sections with antibodies specific to cytokeratins -14 and -8, CD3, and CD4 revealed the presence of medullar and cortical epithelium and mix population of CD3+/CD4+ and CD3+/CD4- T cells. The T cells were associated with the medulla but not with the cortex of the thymus. The immunostaining with an antibody to FoxN1 showed that the protein was expressed in the thymic epithelium. Taken together, we provide evidence that the thymus of a 96-year-old man involuted different kinetics in each of the two thymic lobes. Furthermore, the presence of CD3+/CD4+ and CD3+/CD4-cells gives a hand to the hypothesis that a pool of T-cells may associate with this primary lymphatic organ for as long as there is the available thymic epithelium and be a source of lymphocytes aiding adaptive immune responses to old age.
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3
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Nitta T, Ota A, Iguchi T, Muro R, Takayanagi H. The fibroblast: An emerging key player in thymic T cell selection. Immunol Rev 2021; 302:68-85. [PMID: 34096078 PMCID: PMC8362222 DOI: 10.1111/imr.12985] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 05/04/2021] [Accepted: 05/08/2021] [Indexed: 02/06/2023]
Abstract
Fibroblasts have recently attracted attention as a key stromal component that controls the immune responses in lymphoid tissues. The thymus has a unique microenvironment comprised of a variety of stromal cells, including fibroblasts and thymic epithelial cells (TECs), the latter of which is known to be important for T cell development because of their ability to express self‐antigens. Thymic fibroblasts contribute to thymus organogenesis during embryogenesis and form the capsule and medullary reticular network in the adult thymus. However, the immunological significance of thymic fibroblasts has thus far only been poorly elucidated. In this review, we will summarize the current views on the development and functions of thymic fibroblasts as revealed by new technologies such as multicolor flow cytometry and single cell–based transcriptome profiling. Furthermore, the recently discovered role of medullary fibroblasts in the establishment of T cell tolerance by producing a unique set of self‐antigens will be highlighted.
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Affiliation(s)
- Takeshi Nitta
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Ayami Ota
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Takahiro Iguchi
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Ryunosuke Muro
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Hiroshi Takayanagi
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
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James KD, Jenkinson WE, Anderson G. Non-Epithelial Stromal Cells in Thymus Development and Function. Front Immunol 2021; 12:634367. [PMID: 33717173 PMCID: PMC7946857 DOI: 10.3389/fimmu.2021.634367] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 01/19/2021] [Indexed: 12/23/2022] Open
Abstract
The thymus supports T-cell development via specialized microenvironments that ensure a diverse, functional and self-tolerant T-cell population. These microenvironments are classically defined as distinct cortex and medulla regions that each contain specialized subsets of stromal cells. Extensive research on thymic epithelial cells (TEC) within the cortex and medulla has defined their essential roles during T-cell development. Significantly, there are additional non-epithelial stromal cells (NES) that exist alongside TEC within thymic microenvironments, including multiple subsets of mesenchymal and endothelial cells. In contrast to our current understanding of TEC biology, the developmental origins, lineage relationships, and functional properties, of NES remain poorly understood. However, experimental evidence suggests these cells are important for thymus function by either directly influencing T-cell development, or by indirectly regulating TEC development and/or function. Here, we focus attention on the contribution of NES to thymic microenvironments, including their phenotypic identification and functional classification, and explore their impact on thymus function.
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Affiliation(s)
- Kieran D James
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - William E Jenkinson
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
| | - Graham Anderson
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, United Kingdom
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Nitta T, Takayanagi H. Non-Epithelial Thymic Stromal Cells: Unsung Heroes in Thymus Organogenesis and T Cell Development. Front Immunol 2021; 11:620894. [PMID: 33519827 PMCID: PMC7840694 DOI: 10.3389/fimmu.2020.620894] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Accepted: 11/27/2020] [Indexed: 12/16/2022] Open
Abstract
The stromal microenvironment in the thymus is essential for generating a functional T cell repertoire. Thymic epithelial cells (TECs) are numerically and phenotypically one of the most prominent stromal cell types in the thymus, and have been recognized as one of most unusual cell types in the body by virtue of their unique functions in the course of the positive and negative selection of developing T cells. In addition to TECs, there are other stromal cell types of mesenchymal origin, such as fibroblasts and endothelial cells. These mesenchymal stromal cells are not only components of the parenchymal and vascular architecture, but also have a pivotal role in controlling TEC development, although their functions have been less extensively explored than TECs. Here, we review both the historical studies on and recent advances in our understanding of the contribution of such non-TEC stromal cells to thymic organogenesis and T cell development. In particular, we highlight the recently discovered functional effect of thymic fibroblasts on T cell repertoire selection.
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Affiliation(s)
- Takeshi Nitta
- Department of Immunology, Graduate School of Medicine and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
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Hsu HP, Chen YT, Chen YY, Lin CY, Chen PY, Liao SY, Lim CCY, Yamaguchi Y, Hsu CL, Dzhagalov IL. Heparan sulfate is essential for thymus growth. J Biol Chem 2021; 296:100419. [PMID: 33600795 PMCID: PMC7974028 DOI: 10.1016/j.jbc.2021.100419] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 02/03/2021] [Accepted: 02/11/2021] [Indexed: 12/21/2022] Open
Abstract
Thymus organogenesis and T cell development are coordinated by various soluble and cell-bound molecules. Heparan sulfate (HS) proteoglycans can interact with and immobilize many soluble mediators, creating fields or gradients of secreted ligands. While the role of HS in the development of many organs has been studied extensively, little is known about its function in the thymus. Here, we examined the distribution of HS in the thymus and the effect of its absence on thymus organogenesis and T cell development. We found that HS was expressed most abundantly on the thymic fibroblasts and at lower levels on endothelial, epithelial, and hematopoietic cells. To study the function of HS in the thymus, we eliminated most of HS in this organ by genetically disrupting the glycosyltransferase Ext1 that is essential for its synthesis. The absence of HS greatly reduced the size of the thymus in fetal thymic organ cultures and in vivo, in mice, and decreased the production of T cells. However, no specific blocks in T cell development were observed. Wild-type thymic fibroblasts were able to physically bind the homeostatic chemokines CCL19, CCL21, and CXCL12 ex vivo. However, this binding was abolished upon HS degradation, disrupting the CCL19/CCL21 chemokine gradients and causing impaired migration of dendritic cells in thymic slices. Thus, our results show that HS plays an essential role in the development and growth of the thymus and in regulating interstitial cell migration.
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Affiliation(s)
- Hsuan-Po Hsu
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Yun-Tzu Chen
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Yu-Ying Chen
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Chih-Yu Lin
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Po-Yu Chen
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Shio-Yi Liao
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | | | - Yu Yamaguchi
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA
| | - Chia-Lin Hsu
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan
| | - Ivan L Dzhagalov
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei, Taiwan.
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Sheridan JM, Keown A, Policheni A, Roesley SN, Rivlin N, Kadouri N, Ritchie ME, Jain R, Abramson J, Heng TS, Gray DH. Thymospheres Are Formed by Mesenchymal Cells with the Potential to Generate Adipocytes, but Not Epithelial Cells. Cell Rep 2017; 21:934-942. [DOI: 10.1016/j.celrep.2017.09.090] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 06/28/2017] [Accepted: 09/26/2017] [Indexed: 11/28/2022] Open
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Lucas B, McCarthy NI, Baik S, Cosway E, James KD, Parnell SM, White AJ, Jenkinson WE, Anderson G. Control of the thymic medulla and its influence on αβT-cell development. Immunol Rev 2016; 271:23-37. [PMID: 27088905 PMCID: PMC4982089 DOI: 10.1111/imr.12406] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The thymus is a primary lymphoid tissue that supports the generation of αβT cells. In this review, we describe the processes that give rise to the thymus medulla, a site that nurtures self-tolerant T-cell generation following positive selection events that take place in the cortex. To summarize the developmental pathways that generate medullary thymic epithelial cells (mTEC) from their immature progenitors, we describe work on both the initial emergence of the medulla during embryogenesis, and the maintenance of the medulla during postnatal stages. We also investigate the varying roles that receptors belonging to the tumor necrosis factor receptor superfamily have on thymus medulla development and formation, and highlight the impact that T-cell development has on thymus medulla formation. Finally, we examine the evidence that the thymic medulla plays an important role during the intrathymic generation of distinct αβT-cell subtypes. Collectively, these studies provide new insight into the development and functional importance of medullary microenvironments during self-tolerant T-cell production in the thymus.
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Affiliation(s)
- Beth Lucas
- MRC Centre for Immune RegulationInstitute for Immunology and ImmunotherapyMedical SchoolUniversity of BirminghamBirminghamUK
| | - Nicholas I. McCarthy
- MRC Centre for Immune RegulationInstitute for Immunology and ImmunotherapyMedical SchoolUniversity of BirminghamBirminghamUK
| | - Song Baik
- MRC Centre for Immune RegulationInstitute for Immunology and ImmunotherapyMedical SchoolUniversity of BirminghamBirminghamUK
| | - Emilie Cosway
- MRC Centre for Immune RegulationInstitute for Immunology and ImmunotherapyMedical SchoolUniversity of BirminghamBirminghamUK
| | - Kieran D. James
- MRC Centre for Immune RegulationInstitute for Immunology and ImmunotherapyMedical SchoolUniversity of BirminghamBirminghamUK
| | - Sonia M. Parnell
- MRC Centre for Immune RegulationInstitute for Immunology and ImmunotherapyMedical SchoolUniversity of BirminghamBirminghamUK
| | - Andrea J. White
- MRC Centre for Immune RegulationInstitute for Immunology and ImmunotherapyMedical SchoolUniversity of BirminghamBirminghamUK
| | - William E. Jenkinson
- MRC Centre for Immune RegulationInstitute for Immunology and ImmunotherapyMedical SchoolUniversity of BirminghamBirminghamUK
| | - Graham Anderson
- MRC Centre for Immune RegulationInstitute for Immunology and ImmunotherapyMedical SchoolUniversity of BirminghamBirminghamUK
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Joseph C, Nota C, Fletcher JL, Maluenda AC, Green AC, Purton LE. Retinoic Acid Receptor γ Regulates B and T Lymphopoiesis via Nestin-Expressing Cells in the Bone Marrow and Thymic Microenvironments. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 196:2132-44. [PMID: 26843326 DOI: 10.4049/jimmunol.1501246] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 01/03/2016] [Indexed: 12/16/2023]
Abstract
Vitamin A has essential but largely unexplained roles in regulating lymphopoiesis. We have previously shown that retinoic acid receptor (RAR) γ-deficient mice have hematopoietic defects, some phenotypes of which were microenvironment induced. Bone marrow (BM) microenvironment cells identified by either their expression of nestin (Nes) or osterix (Osx) have previously been shown to have roles in regulating lymphopoiesis. We therefore conditionally deleted Rarγ in Nes- or Osx-expressing microenvironment cells. Osx cell-specific deletion of Rarγ had no impact on hematopoiesis. In contrast, deletion of Rarγ in Nes-expressing cells resulted in reductions in peripheral blood B cells and CD4(+) T cells, accompanied by reductions of immature PreB cells in BM. The mice lacking Rarγ in Nes-expressing cells also had smaller thymi, with reductions in double-negative 4 T cell precursors, accompanied by reduced numbers of both TCRβ(low) immature single-positive CD8(+) cells and double-positive T cells. In the thymus, Nes expression was restricted to thymic stromal cells that expressed cerebellar degeneration-related Ag 1 and lacked expression of epithelial cell adhesion molecule. These cells expressed platelet-derived growth factor α and high transcript levels of Rars, Cxcl12, and stem cell factor (Scf). Short-term treatment of mice with all-trans retinoic acid resulted in increased PreB lymphopoiesis in BM and an increase in thymic double-negative 4 T cells, inverse to that observed upon Nes cell-specific deletion of Rarγ. Collectively, these studies show that RARγ is a regulator of B and T lymphopoiesis via Nes-expressing cells in the BM and thymic microenvironments, respectively.
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Affiliation(s)
- Chacko Joseph
- Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia; and Department of Medicine, St. Vincent's Hospital, Fitzroy, Victoria 3065, Australia
| | - Celeste Nota
- Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia; and
| | - Jessica L Fletcher
- Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia; and
| | - Ana C Maluenda
- Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia; and
| | - Alanna C Green
- Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia; and Department of Medicine, St. Vincent's Hospital, Fitzroy, Victoria 3065, Australia
| | - Louise E Purton
- Stem Cell Regulation Unit, St. Vincent's Institute of Medical Research, Fitzroy, Victoria 3065, Australia; and Department of Medicine, St. Vincent's Hospital, Fitzroy, Victoria 3065, Australia
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10
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Abstract
The thymus is one of the cornerstones of an effective immune system. It produces new T-cells for the naïve T-cell pool, thus refreshing the peripheral repertoire. As we age, the thymus atrophies and there is a decrease in the area of active T-cell production. A decline in the output of the thymus eventually leads to changes in the peripheral T-cell pool which includes increases in the number of cells at or near their replicative limit and contraction of the repertoire. Debate about the age-associated changes in the thymus leading to functional decline centres on whether this is due to problems with the environment provided by the thymus or with defects in the progenitor cell compartment. In mice, the evidence points towards problems in the epithelial component of the thymus and the production of IL-7 (interleukin 7). But there are discussions about how appropriate mouse models are for human aging. We have developed a simple system that utilizes both human keratinocyte and fibroblast cell lines arrayed on a synthetic tantalum-coated matrix to provide a permissive environment for the maturation of human CD34+ haemopoietic progenitor cells into mature CD4+ or CD8+ T-lymphocytes. We have characterized the requirements for differentiation within these cultures and used this system to compare the ability of CD34+ cells derived from different sources to produce mature thymocytes. The TREC (T-cell receptor excision circle) assay was used as a means of identifying newly produced thymocytes.
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Gravano DM, McLelland BT, Horiuchi K, Manilay JO. ADAM17 deletion in thymic epithelial cells alters aire expression without affecting T cell developmental progression. PLoS One 2010; 5:e13528. [PMID: 20976004 PMCID: PMC2958126 DOI: 10.1371/journal.pone.0013528] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 09/20/2010] [Indexed: 12/18/2022] Open
Abstract
Background Cellular interactions between thymocytes and thymic stromal cells are critical for normal T cell development. Thymic epithelial cells (TECs) are important stromal niche cells that provide essential growth factors, cytokines, and present self-antigens to developing thymocytes. The identification of genes that mediate cellular crosstalk in the thymus is ongoing. One candidate gene, Adam17, encodes a metalloprotease that functions by cleaving the ectodomain of several transmembrane proteins and regulates various developmental processes. In conventional Adam17 knockout mice, a non-cell autonomous role for ADAM17 in adult T cell development was reported, which strongly suggested that expression of ADAM17 in TECs was required for normal T cell development. However, knockdown of Adam17 results in multisystem developmental defects and perinatal lethality, which has made study of the role of Adam17 in specific cell types difficult. Here, we examined T cell and thymic epithelial cell development using a conditional knockout approach. Methodology/Principal Findings We generated an Adam17 conditional knockout mouse in which floxed Adam17 is deleted specifically in TECs by Cre recombinase under the control of the Foxn1 promoter. Normal T cell lineage choice and development through the canonical αβ T cell stages was observed. Interestingly, Adam17 deficiency in TECs resulted in reduced expression of the transcription factor Aire. However, no alterations in the patterns of TEC phenotypic marker expression and thymus morphology were noted. Conclusions/Significance In contrast to expectation, our data clearly shows that absence of Adam17 in TECs is dispensable for normal T cell development. Differentiation of TECs is also unaffected by loss of Adam17 based on phenotypic markers. Surprisingly, we have uncovered a novel genetic link between Adam17and Aire expression in vivo. The cell type in which ADAM17 mediates its non-cell autonomous impact and the mechanisms by which it regulates intrathymic T cell development remain to be identified.
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Affiliation(s)
- David M. Gravano
- School of Natural Sciences, University of California at Merced, Merced, California, United States of America
| | - Bryce T. McLelland
- School of Natural Sciences, University of California at Merced, Merced, California, United States of America
| | - Keisuke Horiuchi
- Department of Orthopedic Surgery and Department of Anti-aging Orthopedic Research, School of Medicine, Keio University, Tokyo, Japan
| | - Jennifer O. Manilay
- School of Natural Sciences, University of California at Merced, Merced, California, United States of America
- * E-mail:
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Mendes-da-Cruz DA, Lepelletier Y, Brignier AC, Smaniotto S, Renand A, Milpied P, Dardenne M, Hermine O, Savino W. Neuropilins, semaphorins, and their role in thymocyte development. Ann N Y Acad Sci 2009; 1153:20-8. [PMID: 19236324 DOI: 10.1111/j.1749-6632.2008.03980.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Some molecules described in the nervous system are also expressed in cells involved in the control of the immune response, suggesting they have a role as common mechanisms between neuroendocrine and immune systems. In this review, we focus on the expression and role of neuropilins (NPs) and their soluble ligands class 3 semaphorins in thymus physiology, particularly migration of developing thymocytes. We also discuss the concept of multivectorial thymocyte migration, including semaphorins, as a new individual cell migration vector.
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Itoi M, Tsukamoto N, Yoshida H, Amagai T. Mesenchymal cells are required for functional development of thymic epithelial cells. Int Immunol 2007; 19:953-64. [PMID: 17625108 DOI: 10.1093/intimm/dxm060] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Epithelial-mesenchymal interactions have essential roles in thymus organogenesis. Mesenchymal cells are known to be required for epithelial cell proliferation. However, the contribution of mesenchymal cells to thymic epithelial cell differentiation is still unclear. In the present study, we have investigated the roles of mesenchymal cells in functional development of epithelial cells in the thymus anlage in patch (ph) mutant mice, which have a primarily defect in mesenchymal cells caused by the absence of platelet-derived growth factor receptor alpha expression. In the ph/ph thymus anlage, T cell progenitors migrate normally among the epithelial cells, however, they are severely impaired to proliferate and differentiate to CD25-positive cells. Epithelial cells of the ph/ph thymus anlage show severely impaired proliferation and expression of functional molecules, such as SCF, Delta-like 4 and MHC class II, which have crucial roles in T cell development. Moreover, the cultured ph/ph thymus anlage fails to develop into a mature organ supporting full T cell development. Addition of intact thymic mesenchymal cells to organ culture induces development of the ph/ph thymus anlage. In the cultured lobes, added mesenchymal cells contribute to form not only the capsule but also the meshwork structure mingled with epithelial cells. Our present results strongly suggest the roles of mesenchymal cells in functional development of epithelial cells in thymus organogenesis. In addition, our data suggest that mesenchymal cells are required to create the thymic microenvironment and to maintain epithelial architecture and function.
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Affiliation(s)
- Manami Itoi
- Department of Immunology and Microbiology, Meiji University of Oriental Medicine, Hiyoshi-cho, Nantan, Kyoto 629-0392, Japan.
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14
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Graham VA, Marzo AL, Tough DF. A role for CD44 in T cell development and function during direct competition between CD44+ and CD44- cells. Eur J Immunol 2007; 37:925-34. [PMID: 17330818 DOI: 10.1002/eji.200635882] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The role of CD44 in T cell biology remains incompletely understood. Although studies using anti-CD44 antibodies have implicated this cell adhesion molecule in a variety of important T cell processes, few T cell defects have been reported in CD44-deficient mice. We have assessed the requirement for CD44 in T cell development and mature T cell function by analyzing mice in which CD44(-/-) and WT cells were produced simultaneously. In mixed (CD44(-/-) + CD44(+/+)) bone marrow chimeras, production of CD44(-/-) T cells was shown to be reduced compared to WT cells due to inefficient intrathymic development. In addition, mature CD44(-/-) CD8(+) T cells generated a substantially lower response than WT T cells after infection of mice with lymphocytic choriomeningitis virus, with the reduction in response apparent in both lymphoid and non-lymphoid tissues. Overall, these results demonstrate a poor capacity of CD44(-/-) T lineage cells to compete with WT cells at multiple levels, implicating CD44 in normal T cell function.
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Affiliation(s)
- Victoria A Graham
- The Edward Jenner Institute for Vaccine Research, Compton, Newbury, Berkshire, UK
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15
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Gray DHD, Tull D, Ueno T, Seach N, Classon BJ, Chidgey A, McConville MJ, Boyd RL. A unique thymic fibroblast population revealed by the monoclonal antibody MTS-15. THE JOURNAL OF IMMUNOLOGY 2007; 178:4956-65. [PMID: 17404277 DOI: 10.4049/jimmunol.178.8.4956] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
T cell differentiation in the thymus is dependent upon signals from thymic stromal cells. Most studies into the nature of these signals have focused only on the support provided by the thymic epithelium, but there is an emerging view that other stromal cells such as mesenchymal fibroblasts may also be involved. Study of the latter has been hindered by a lack of appropriate markers, particularly those allowing their isolation. In this study, we describe a new surface marker of thymic stroma, MTS-15, and demonstrate its specificity for fibroblasts and a subset of endothelial cells. Coculture experiments showed that the determinant could be transferred between cells. Extensive biochemical analysis demonstrated that the Ag bound by MTS-15 was the glycosphingolipid Forssman determinant, consistent with the distribution observed. Transcriptional analysis of purified MTS-15(+) thymic fibroblasts revealed a unique expression profile for a number of chemokines and growth factors important to thymocyte and epithelial cell development. In a model of cyclophosphamide-induced thymic involution and regeneration, fibroblasts were found to expand extensively and express growth factors important to epithelial proliferation and increased T cell production just before thymic regeneration. Overall, this study identifies a useful marker of thymic fibroblasts and highlights this subpopulation as a key player in thymic function by virtue of their support of both thymocytes and epithelial cells.
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Affiliation(s)
- Daniel H D Gray
- Monash Immunology and Stem Cell Laboratories, Monash University, Clayton, Victoria, Australia
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16
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Abstract
T-cell development occurs principally in the thymus. Here, immature progenitor cells are guided through the differentiation and selection steps required to generate a complex T-cell repertoire that is both self-tolerant and has propensity to bind self major histocompatibility complex. These processes depend on an array of functionally distinct epithelial cell types within the thymic stroma, which have a common developmental origin in the pharyngeal endoderm. Here, we describe the structural and phenotypic attributes of the thymic stroma, and review current cellular and molecular understanding of thymus organogenesis.
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Affiliation(s)
- Craig S Nowell
- Institute for Stem Cell Research, University of Edinburgh, UK
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17
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Pongracz JE, Parnell SM, Jones T, Anderson G, Jenkinson EJ. Overexpression of ICAT highlights a role for catenin-mediated canonical Wnt signalling in early T cell development. Eur J Immunol 2006; 36:2376-83. [PMID: 16897815 DOI: 10.1002/eji.200535721] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Transcription factors of the T cell factor/lymphoid enhancing factor (Tcf/Lef) family are key regulators in the development of T cell precursors to the CD4+8+ stage. These factors are known targets of the canonical Wnt signalling pathway, and regulate transcription of Wnt target genes following interaction with the armadillo repeat-containing protein beta-catenin. However, as recent studies show normal thymocyte maturation in the absence of either beta-catenin or its homologue gamma-catenin, the role of Wnt signalling in Tcf/Lef activation during T cell development is controversial. To directly investigate the importance of catenin-mediated Wnt signalling in early thymocytes, we have compared the expression of beta- and gamma-catenin and analysed distinct stages of T cell precursor maturation following overexpression of inhibitor of beta-catenin and Tcf (ICAT), which inhibits Wnt signalling by preventing binding of armadillo repeat-containing proteins to Tcf/Lef. By direct retroviral gene targeting of CD4-8- and CD4+8+ precursors, we show that ICAT overexpression inhibits the CD4-8--to-CD4+8+ transition, but not the CD4+8+-to-CD4+8- or -CD4-8+ transition. Collectively, our data support a model in which canonical Wnt signalling influences T cell development in the thymus by playing an essential role in the maturation of CD4-8- but not CD4+8+ thymocytes.
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Affiliation(s)
- Judit E Pongracz
- MRC Centre for Immune Regulation, Division of Immunity and Infection, Institute for Biomedical Research, University of Birmingham, Birmingham, UK
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18
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Anderson G, Jenkinson WE, Jones T, Parnell SM, Kinsella FAM, White AJ, Pongrac'z JE, Rossi SW, Jenkinson EJ. Establishment and functioning of intrathymic microenvironments. Immunol Rev 2006; 209:10-27. [PMID: 16448531 DOI: 10.1111/j.0105-2896.2006.00347.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The thymus supports the production of self-tolerant T cells from immature precursors. Studying the mechanisms regulating the establishment and maintenance of stromal microenvironments within the thymus therefore is essential to our understanding of T-cell production and ultimately immune system functioning. Despite our ability to phenotypically define stromal cell compartments of the thymus, the mechanisms regulating their development and the ways by which they influence T-cell precursors are still unclear. Here, we review recent findings and highlight unresolved issues relating to the development and functioning of thymic stromal cells.
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Affiliation(s)
- Graham Anderson
- MRC Center for Immune Regulation, Division of Immunity and Infection, Institute For Biomedical Research, Medical School, University of Birmingham, Edgbaston, Birmingham, UK.
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19
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Gray DHD, Seach N, Ueno T, Milton MK, Liston A, Lew AM, Goodnow CC, Boyd RL. Developmental kinetics, turnover, and stimulatory capacity of thymic epithelial cells. Blood 2006; 108:3777-85. [PMID: 16896157 DOI: 10.1182/blood-2006-02-004531] [Citation(s) in RCA: 323] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Despite the importance of thymic stromal cells to T-cell development, relatively little is known about their biology. Here, we use single-cell analysis of stromal cells to analyze extensive changes in the number and composition of thymic stroma throughout life, revealing a surprisingly dynamic population. Phenotypic progression of thymic epithelial subsets was assessed at high resolution in young mice to provide a developmental framework. The cellular and molecular requirements of adult epithelium were studied, using various mutant mice to demonstrate new cross talk checkpoints dependent on RelB in the cortex and CD40 in the medulla. With the use of Ki67 and BrdU labeling, the turnover of thymic epithelium was found to be rapid, but then diminished on thymic involution. The various defects in stromal turnover and composition that accompanied involution were rapidly reversed following sex steroid ablation. Unexpectedly, mature cortical and medullary epithelium showed a potent capacity to stimulate naive T cells, comparable to that of thymic dendritic cells. Overall, these studies show that the thymic stroma is a surprisingly dynamic population and may have a more direct role in negative selection than previously thought.
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Affiliation(s)
- Daniel H D Gray
- Monash Immunology and Stem Cell Laboratories (MISCL), Level 3, STRIP, Building 75, Monash University, Wellington Road, Clayton, Victoria, 3800, Australia
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20
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Goldschneider I. Cyclical mobilization and gated importation of thymocyte progenitors in the adult mouse: evidence for a thymus-bone marrow feedback loop. Immunol Rev 2006; 209:58-75. [PMID: 16448534 DOI: 10.1111/j.0105-2896.2006.00354.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
It has recently been observed, as in the fetal thymus, that the importation of hematogenous thymocyte progenitors by the adult thymus is a gated phenomenon, whereby saturating numbers of progenitors periodically enter the thymus and occupy a finite number of intrathymic niches. In addition, the mobilization of thymocyte progenitors from the bone marrow appears to be a cyclical process that coincides temporally with the periods of thymic receptivity (open gate). It is proposed that these events are coordinated by a thymus-bone marrow feedback loop in which a wave of developing triple negative (CD3- CD4- CD8-) thymocytes interacts with stromal cells in the stratified regions of the thymus cortex to sequentially induce the release of diffusible cytokines that regulate the production, mobilization, and recruitment of thymocyte progenitors. The likely components of this feedback loop are described here, as are the properties of the intrathymic vascular gates and niches for thymocyte progenitors. The cyclical production and release of thymocyte progenitors from the bone marrow is placed in the context of a general phenomenon of oscillatory feedback regulation involving all lymphohemopoietic cell lineages. Lastly, the question of whether the gated (as opposed to the continuous) entry of thymocyte progenitors is essential for normal thymocytopoiesis in adult life is discussed.
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Affiliation(s)
- Irving Goldschneider
- Department of Immunology, University of Connecticut Health Center, Farmington, CT 06030, USA.
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21
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Brelinska R, Malinska A. Homing of hemopoietic precursor cells to the fetal rat thymus: intercellular contact-controlled cell migration and development of the thymic microenvironment. Cell Tissue Res 2005; 322:393-405. [PMID: 16133143 DOI: 10.1007/s00441-005-1079-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Accepted: 12/22/2004] [Indexed: 10/25/2022]
Abstract
Colonization of rat thymic anlage by the first wave of hemopoietic precursor cells (HPc) was investigated by means of transmission electron microscopy and immunocytochemistry. HPc began migration into the thymic anlage between 13 and 13.5 gestation days (GD), terminated colonization at about GD 16, and migrated sequentially through the two compartments of the thymic anlage under the control of typical populations of stromal cells. First, HPc migrated through the external compartment of the perithymic mesenchyme, tightly interconnected with fibroblasts. The type of junctions between the cells indicated that the fibroblasts played a role in the control of HPc trafficking and in their entrance to the epithelial compartment. The second stage of colonization was initiated by the entrance of HPc to the epithelial compartment and their interaction with thymic epithelial cells (TECs). Based on morphological criteria, two populations of HPc were distinguished that colonized the anlage at various stages of its development. The predominant population with ultrastructural traits common to thymocytes "homed" into the epithelial type primordium. A small number of HPc, identified by protein S-100 expression and by Birbeck's granules as precursors of dendritic cells, colonized lymphoepithelial anlage in which subsets of cortical and medullary TECs could be distinguished. Thymocyte migration and their reciprocal interactions with cortical TECs differed from the trafficking of dendritic cells toward the medulla. The results demonstrated the influence of maturing thymocytes on the development of cortical epithelial cells and the dynamic organization of the medullary microenvironment with direct involvement of dendritic cells.
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Affiliation(s)
- Renata Brelinska
- Department of Histology and Embryology, University of Medical Sciences, 60-781, Poznań, Poland.
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22
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Yamazaki H, Sakata E, Yamane T, Yanagisawa A, Abe K, Yamamura KI, Hayashi SI, Kunisada T. Presence and distribution of neural crest-derived cells in the murine developing thymus and their potential for differentiation. Int Immunol 2005; 17:549-58. [PMID: 15837714 DOI: 10.1093/intimm/dxh237] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Neural crest (NC) cells are multipotent cells that can differentiate into melanocytes, neurons, glias and myofibroblasts. They migrate into the fetal thymus on embryonic day (E) 12 in mice and may participate in thymic organogenesis. Although the abnormality of migration and distribution of NC cells in the thymus results in immunodeficiency, the spatial and temporal presence of their progeny cells has not been defined in detail. In this study, we traced NC-derived cells based on the myelin protein zero gene promoter-Cre-mediated excision. We demonstrated that large numbers of NC-derived cells in the thymus were detected on E11.5 to E16.5 but rarely on E17.5. A colony formation assay of single thymic cells demonstrated that multipotent cells with the potential to differentiate into melanocytes, neurons and/or glias were present in the E14.5 and E15.5 but not in the E17.5 fetal thymus. Furthermore, we confirmed that these multipotent cells were NC-derived cells. Taken together, these findings imply that multipotent NC-derived cells are present in the developing thymus, but rarely in this organ at a later stage, suggesting that NC-derived cells may play roles in thymic organogenesis at an early embryonic stage.
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Affiliation(s)
- Hidetoshi Yamazaki
- Department of Genetic Medicine and Regenerative Therapeutics, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Science, Yonago 683-8503, Japan.
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23
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Savino W, Cotta-de-Almeida V, van Buul-Offers SC, Koster JG, Dardenne M. Abnormal thymic microenvironment in insulin-like growth factor-II transgenic mice. Neuroimmunomodulation 2005; 12:100-12. [PMID: 15785112 DOI: 10.1159/000083582] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Accepted: 06/08/2004] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES Intrathymic T cell differentiation is driven by the thymic microenvironment, a tridimensional network of cells and extracellular matrix (ECM). Previous data showed that lymphoid and microenvironmental compartments are under the control of hormones and growth factors. We then attempted to define if insulin-like growth factor-II (IGF-II) was also involved in such a control. METHODS We used IGF-II transgenic (Tg) mice and studied their thymic microenvironment by immunohistochemistry. Moreover, we evaluated thymocytes in terms of their ability to adhere to thymic epithelial cells and to migrate through epithelial cells and ECM. RESULTS Transgenic IGF-II expression results in abnormalities of the thymic epithelium. Terminal differentiation of thymic epithelial cells (TEC) is modified, with the appearance of large clusters of cells immunoreactive to the monoclonal antibody KL1, which specifically recognizes highly differentiated TEC. Accordingly, treatment of cultured TEC with exogenous IGF-II induces the appearance of KL1+ cells and increases TEC proliferation. IGF-II Tg animals exhibit increased serum levels of the TEC-derived hormone thymulin. These effects were seen even when the IGF-II transgene was inserted in dwarf mice. Moreover, deposition of fibronectin and laminin is also enhanced in IGF-II Tg mouse thymus and in IGF-II-treated TEC cultures. Furthermore, ECM-mediated interactions between thymocytes and TEC are affected by exogenous IGF-II, as exemplified by the enhancement of thymocyte adhesion to TEC monolayers and thymocyte migration in thymic nurse cell complexes. CONCLUSIONS Our data indicate that IGF-II pleiotropically affects the thymic epithelium, both in vivo and in vitro, and that some of these changes may have consequences on thymocyte/TEC interactions.
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Affiliation(s)
- Wilson Savino
- Laboratory on Thymus Research, Department of Immunology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
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24
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Ayres-Martins S, Lannes-Vieira J, Farias-De-Oliveira DA, Brito JM, Villa-Verde DMS, Savino W. Phagocytic cells of the thymic reticulum interact with thymocytes via extracellular matrix ligands and receptors. Cell Immunol 2004; 229:21-30. [PMID: 15331325 DOI: 10.1016/j.cellimm.2004.06.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2004] [Accepted: 06/07/2004] [Indexed: 11/16/2022]
Abstract
We previously showed that, in the context of thymic epithelial cells, thymocyte migration is partially controlled by extracellular matrix (ECM)-mediated interactions. Herein we evaluated whether these interactions could be involved in cell migration related events in the context of non-epithelial cells of the thymic microenvironment, the phagocytic cells of the thymic reticulum (PTR). We first showed, by immunocytochemistry, cytofluorometry, and RT-PCR, that PTR produce ECM components, including fibronectin and laminin, and express the corresponding integrin-type receptors, VLA-4, VLA-5, and VLA-6. Thymocytes adhere onto PTR monolayers, with immature CD4(+)CD8(+) cells being predominant. Importantly, such an adhesion is partially mediated by ECM ligands and receptors, since it was impaired by anti-ECM or anti-ECM receptor antibodies. Conjointly, our data reveal that the ECM-dependence for thymocyte adhesion onto the thymic microenvironment is not restricted to the epithelial cells, being also seen when they encounter non-epithelial phagocytic cells.
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Affiliation(s)
- Silvana Ayres-Martins
- Laboratory on Thymus Research, Department of Immunology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil
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25
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Abstract
Lymphoid organs represent a specialized microenvironment for interaction of stromal and lymphoid cells. In primary lymphoid organs, these interactions are required to establish a self-tolerant repertoire of lymphocytes. While detailed information is available about the genes that control lymphocyte differentiation, little is known about the genes that direct the establishment and differentiation of principal components of such microenvironments. Here, we discuss genetic studies addressing the role of thymic epithelial cells (TECs) during thymopoiesis. We have identified an evolutionarily conserved key regulator of TEC differentiation, Foxn1, that is required for the immigration of prothymocytes into the thymic primordium. Because Foxn1 specifies the prospective endodermal domain that gives rise to thymic epithelial cells, it can be used to identify the evolutionary origins of this specialized cell type. In the course of these studies, we have found that early steps of thymus development in zebrafish are very similar to those in mice. Subsequently, we have used chemical mutagenesis to derive zebrafish lines with aberrant thymus development. Strengths and weaknesses of mouse and zebrafish models are largely complementary such that genetic analysis of mouse and zebrafish mutants may lead to a better understanding of thymus development.
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Affiliation(s)
- Thomas Boehm
- Department of Developmental Immunology, Max-Planck-Institute of Immunobiology, Freiburg, Germany.
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26
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Abstract
The thymus is a complex epithelial organ in which thymocyte development is dependent upon the sequential contribution of morphologically and phenotypically distinct stromal cell compartments. It is these microenvironments that provide the unique combination of cellular interactions, cytokines, and chemokines to induce thymocyte precursors to undergo a differentiation program that leads to the generation of functional T cells. Despite the indispensable role of thymic epithelium in the generation of T cells, the mediators of this process and the differentiation pathway undertaken by the primordial thymic epithelial cells are not well defined. There is a lack of lineage-specific cell-surface-associated markers, which are needed to characterize putative thymic epithelial stem cell populations. This review explores the role of thymic stromal cells in T-cell development and thymic organogenesis, as well as the molecular signals that contribute to the growth and expansion of primordial thymic epithelial cells. It highlights recent advances in these areas, which have allowed for a lineage relationship amongst thymic epithelial cell subsets to be proposed. While many fundamental questions remain to be addressed, collectively these works have broadened our understanding of how the thymic epithelium becomes specialized in the ability to support thymocyte differentiation. They should also facilitate the development of novel, rationally based therapeutic strategies for the regeneration and manipulation of thymic function in the treatment of many clinical conditions in which defective T cells have an important etiological role.
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Affiliation(s)
- Jason Gill
- Department of Pathology and Immunology, Monash University, Faculty of Medicine, Nursing and Health Sciences, Alfred Medical Research and Education Precinct, Prahran, Australia.
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27
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Jenkinson WE, Jenkinson EJ, Anderson G. Differential requirement for mesenchyme in the proliferation and maturation of thymic epithelial progenitors. J Exp Med 2003; 198:325-32. [PMID: 12860931 PMCID: PMC2194072 DOI: 10.1084/jem.20022135] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Formation of a mature thymic epithelial microenvironment is an essential prerequisite for the generation of a functionally competent T cell pool. It is likely that recently identified thymic epithelial precursors undergo phases of proliferation and differentiation to generate mature cortical and medullary thymic microenvironments. The mechanisms regulating development of immature thymic epithelial cells are unknown. Here we provide evidence that expansion of embryonic thymic epithelium is regulated by the continued presence of mesenchyme. In particular, mesenchymal cells are shown to mediate thymic epithelial cell proliferation through their provision of fibroblast growth factors 7 and 10. In contrast, differentiation of immature thymic epithelial cells, including acquisition of markers of mature cortical and medullary epithelium, occurs in the absence of ongoing mesenchymal support. Collectively, our data define a role for mesenchymal cells in thymus development, and indicate distinct mechanisms regulate proliferation and differentiation of immature thymic epithelial cells. In addition, our findings may aid in studies aimed at developing strategies to enhance thymus reconstitution and functioning in clinical certain contexts where thymic epithelial cell function is perturbed.
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Affiliation(s)
- William E Jenkinson
- Department of Anatomy, Division of Immunity and Infection, MRC Centre for Immune Regulation, Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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28
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Erickson M, Morkowski S, Lehar S, Gillard G, Beers C, Dooley J, Rubin JS, Rudensky A, Farr AG. Regulation of thymic epithelium by keratinocyte growth factor. Blood 2002; 100:3269-78. [PMID: 12384427 DOI: 10.1182/blood-2002-04-1036] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Here we demonstrate that keratinocyte growth factor (KGF) and FGFR2IIIb signaling can affect development and function of thymic epithelium (TE) and that alphabeta-lineage thymocytes contribute to intrathymic levels of KGF. Thymocyte expression of KGF is developmentally regulated, being undetectable in CD3-4-8- thymocytes and expressed at highest levels by mature CD4 or CD8 thymocytes. Exposure of thymocyte-depleted fetal thymic lobes to KGF resulted in reduced thymic epithelial expression of class II major histocompatibility complex (MHC), invariant chain (Ii), and cathepsin L (CatL) molecules involved in thymocyte-positive selection and also stimulated expression of the cytokines interleukin 6 (IL-6) and thymic stromal-derived lymphopoietin (TSLP), while having little effect on IL-7 or stem cell factor expression. Within intact fetal thymic organ culture (FTOC), exogenous KGF impairs the generation of CD4 thymocytes. Two lines of evidence point to responsiveness of the medullary TE compartment to KGF and FGFR2IIIb signaling. First, the medullary compartment is expanded in intact FTOC exposed to KGF in vitro. Second, in the RAG-deficient thymus, where the thymocytes do not express detectable levels of KGF message, the hypoplastic medullary TE compartment can be expanded by administration of recombinant KGF in vivo. This expansion is accompanied by restoration of the normal profile of medullary TE-associated chemokine expression in the RAG2(-/-) thymus. Collectively, these findings point to a role for KGF and FGFR signaling in the development and function of thymic epithelium.
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MESH Headings
- Animals
- Antigens, Differentiation, B-Lymphocyte/biosynthesis
- Antigens, Differentiation, B-Lymphocyte/genetics
- CD4-Positive T-Lymphocytes/cytology
- CD4-Positive T-Lymphocytes/metabolism
- Cathepsin L
- Cathepsins/biosynthesis
- Cathepsins/genetics
- Clonal Deletion
- Cysteine Endopeptidases
- Cytokines/biosynthesis
- Cytokines/genetics
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Epithelial Cells/drug effects
- Female
- Fibroblast Growth Factor 1/pharmacology
- Fibroblast Growth Factor 10
- Fibroblast Growth Factor 2/pharmacology
- Fibroblast Growth Factor 7
- Fibroblast Growth Factors/biosynthesis
- Fibroblast Growth Factors/genetics
- Fibroblast Growth Factors/pharmacology
- Fibroblast Growth Factors/physiology
- Histocompatibility Antigens Class II/biosynthesis
- Histocompatibility Antigens Class II/genetics
- Humans
- Interleukin-6/biosynthesis
- Interleukin-6/genetics
- Lysosomes/enzymology
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Nuclear Proteins
- Organ Culture Techniques
- Receptor, Fibroblast Growth Factor, Type 2
- Receptors, Fibroblast Growth Factor/drug effects
- Receptors, Fibroblast Growth Factor/genetics
- Receptors, Fibroblast Growth Factor/physiology
- Recombinant Fusion Proteins/pharmacology
- Signal Transduction
- Stromal Cells/metabolism
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/embryology
- Thymic Stromal Lymphopoietin
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Affiliation(s)
- Matthew Erickson
- Department of Biological Structure, School of Medicine, Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195-7420, USA
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29
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Prockop SE, Palencia S, Ryan CM, Gordon K, Gray D, Petrie HT. Stromal cells provide the matrix for migration of early lymphoid progenitors through the thymic cortex. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:4354-61. [PMID: 12370368 DOI: 10.4049/jimmunol.169.8.4354] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
During steady state lymphopoiesis in the postnatal thymus, migration of precursors outward from the deep cortex toward the capsule is required for normal differentiation. Such migration requires, at a minimum, expression of adhesive receptors on the migrating lymphoid cells, as well as a stable matrix of their ligands persisting throughout the region of migration. In this study, we address the nature of this adhesive matrix. Although some precursor stages bound efficiently to extracellular matrix ligands, a specific requirement for the cell surface ligand VCAM-1 was also found. In situ analysis revealed that early precursors are found in intimate contact with a matrix formed by stromal cells in the cortex, a proportion of which expresses VCAM-1. In vivo administration of an anti-VCAM-1 Ab resulted in decreased thymic size and altered distribution of early precursors within the cortex. These results indicate that precursors migrating outward through the cortex may use a cellular, rather than extracellular, matrix for adhesion, and suggest that the VCAM-1(+) subset of cortical stroma may play a crucial role in supporting the migration of early precursors in the steady state thymus.
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Affiliation(s)
- Susan E Prockop
- Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10021, USA
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30
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Gill J, Malin M, Holländer GA, Boyd R. Generation of a complete thymic microenvironment by MTS24(+) thymic epithelial cells. Nat Immunol 2002; 3:635-42. [PMID: 12068292 DOI: 10.1038/ni812] [Citation(s) in RCA: 212] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The epithelial component of the thymic microenvironment is indispensable for the generation of T lymphocytes. Although the heterogeneity of this epithelium is well documented, little is known about precursor-progeny relationships between distinct thymic epithelial lineages. Here we characterized a thymic epithelial cell subpopulation identified by the cell surface glycoprotein MTS24. These cells contained epithelial progenitor cells that were competent and sufficient to fully reconstitute the complex thymic epithelial microenvironment that supported normal T cell development.
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Affiliation(s)
- Jason Gill
- Department of Pathology and Immunology, Monash University Medical School, Commercial Road, Prahran, Melbourne 3181, Australia.
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31
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Savino W, Mendes-da-Cruz DA, Silva JS, Dardenne M, Cotta-de-Almeida V. Intrathymic T-cell migration: a combinatorial interplay of extracellular matrix and chemokines? Trends Immunol 2002; 23:305-13. [PMID: 12072370 DOI: 10.1016/s1471-4906(02)02224-x] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Cell migration is crucial for intrathymic T-cell differentiation. Chemokines and extracellular matrix proteins per se induce thymocyte migration, and recent data suggest a combinatorial role for these molecules in this event. For example, thymocyte migration induced by fibronectin plus CXCL12/SDF1-alpha (stromal cell-derived factor1-alpha) is higher than that elicited by the chemokine alone. If such interactions are relevant in the thymus, abnormal expression of any of these ligands and/or their corresponding receptors will lead to defects in thymocyte migration. At least in the murine model of Chagas disease, this seems to be the case. Therefore a better knowledge of this complex biological circuitry will provide new clues for understanding thymus physiology and designing therapeutic strategies targeting developing T cells.
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Affiliation(s)
- Wilson Savino
- Laboratory on Thymus Research, Dept of Immunology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Ave Brasil 4365, Manguinhos, 21045-900, Rio de Janeiro, Brazil.
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32
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Hetzer-Egger C, Schorpp M, Haas-Assenbaum A, Balling R, Peters H, Boehm T. Thymopoiesis requires Pax9 function in thymic epithelial cells. Eur J Immunol 2002; 32:1175-81. [PMID: 11932925 DOI: 10.1002/1521-4141(200204)32:4<1175::aid-immu1175>3.0.co;2-u] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The epithelial thymic anlage develops from the third pharyngeal pouch. Pax9 is expressed in the entire pharyngeal endoderm, and its function is required for normal development of organs derived from pharyngeal pouches. Here, we show that in Pax9 null mice, the thymic anlage develops as an ectopic polyp-like structure in the larynx. It expresses Whn/Foxn1, a marker of thymic epithelium, but fails to perform the normal caudo-ventral movement to the upper mediastinum. The thymic rudiment contains mesenchymal cells, blood vessels and is colonized by T cell progenitors. However, from embryonic day 14.5 onwards, the size of the Pax9 mutant thymus is severely reduced. Whereas expression of TCRbeta chain genes is readily detectable in the mutant thymus, no expression of the TCRgamma chain was detectable. Our results identify a new genetically defined control point of thymopoiesis.
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MESH Headings
- Animals
- Antigens, CD/biosynthesis
- Antigens, CD/genetics
- Cell Differentiation
- Cell Lineage
- DNA-Binding Proteins/biosynthesis
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Epithelial Cells/cytology
- Fetal Proteins/biosynthesis
- Fetal Proteins/genetics
- Forkhead Transcription Factors
- Gene Expression Regulation, Developmental
- Gestational Age
- Larynx/embryology
- Mediastinum/embryology
- Mice
- Mice, Knockout
- Morphogenesis
- PAX9 Transcription Factor
- Pharynx/embryology
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, gamma-delta/biosynthesis
- Receptors, Antigen, T-Cell, gamma-delta/genetics
- Specific Pathogen-Free Organisms
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/embryology
- Transcription Factors/biosynthesis
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transcription Factors/physiology
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33
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Foss DL, Donskoy E, Goldschneider I. Functional demonstration of intrathymic binding sites and microvascular gates for prothymocytes in irradiated mice. Int Immunol 2002; 14:331-8. [PMID: 11867569 DOI: 10.1093/intimm/14.3.331] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Quantitative intrathymic (i.t.) and i.v. adoptive transfer assays for prothymocytes show strict log dose saturation kinetics, consistent with a finite number of i.t. binding sites (microenvironmental niches). This inference is supported here by demonstration of competitive antagonism obeying one-on-one receptor occupancy kinetics during the establishment of thymic chimerism in irradiated adult mice. The results of primary and secondary transfer experiments suggested that hematogenous precursors (i) enter specific i.t. niches between 4 and 24 h after injection, (ii) compete reversibly with subsequently introduced precursors, (iii) establish insurmountable competition within 5-7 days, (iv) mature through the initial stages of thymocytopoiesis preceding proliferative expansion, and (v) vacate the niches between 7 and 14 days after entry. The results also suggested that, as in non-irradiated mice, prothymocyte importation in irradiated mice is a gated phenomenon. Gate closure was indicated by the inability of i.v.-, but not i.t.-, injected bone marrow (BM) cells to induce thymic chimerism when administered 7--14 days after a primary injection and gate opening by the ability of i.v.-injected BM cells to induce thymic chimerism in competition with circulating host prothymocytes. Gate closing was log dose-responsive and could be induced in individual thymic lobes by unilateral i.t. injection, whereas gate opening, which occurs bilaterally, was not initiated until most of the niches for prothymocytes had been vacated. We therefore posit the existence of a series of associated microvascular gates and microenvironmental niches that act in concert to regulate prothymocyte importation and early thymocyte differentiation.
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Affiliation(s)
- Deborah L Foss
- Department of Pathology, School of Medicine, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-3105, USA
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34
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Feng JM, Fernandes AO, Campagnoni AT. Golli-myelin basic proteins delineate the nerve distribution of lymphoid organs. J Neuroimmunol 2002; 123:1-8. [PMID: 11880143 DOI: 10.1016/s0165-5728(01)00458-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The golli-myelin basic proteins (MBPs) have been known to mark the nerve fiber extensions in both the peripheral nervous system (PNS) and the central nervous system. In this paper, we show that the nerve fibers revealed by neurofilament (NF) antibody staining in thymus and spleen, colocalized with golli in the capsular, trabecular (tr), and vasculature (v) systems. In the thymus, the density of these fibers was greater in the medulla than in the cortex. In the spleen, the golli immunoreactive fibers were seen within the capsule (ca), trabeculae, and along the artery tree, as well as the fine nerve fiber networks in the periarteriolar lymphoid sheath (PALS). Golli immunoreactivity appeared to colocalize with ER-TR7, a putative marker of connective tissue in lymphoid organs. However, further examination by Western blot analysis and immunohistochemistry performed on golli "knock out" mice showed that the antigens recognized by these two antibodies were different. The reason for the apparent colocalization of golli and ER-TR7 appears to be due to the close physical association of nerve fibers with connective tissue in these organs. These results suggest that golli immunoreactivity can visualize the distribution of nerve fibers in these lymphoid organs.
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Affiliation(s)
- Ji Ming Feng
- Developmental Biology Group, Neuropsychiatric Institute, University of California, Los Angeles, Medical School, Los Angeles, CA 90024, USA
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35
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Abstract
The complexity of the lymphostromal interplay that is essential to alphabetaT-cell development is reflected by the heterogeneity of both lymphocytes and thymic stromal cells. While panels of monoclonal antibodies have described many of the cellular components of these microenvironments, the means to quantify stromal cell subsets using flow cytometry remains poorly defined. This study refines and compares various stromal cell isolation procedures and determines the effects of various digestion enzymes on important surface molecules. Three- and four-color flow cytometry is used to correlate established and novel stromal cell markers to define thymic fibroblasts, epithelium and a unique subset of thymic endothelium that express MHC class II. This work provides a basis for the purification of thymic stromal cells for further phenotypic, functional and genetic analysis.
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Affiliation(s)
- D H D Gray
- Department of Pathology and Immunology, Monash Medical School, Commercial Road, Prahran, 3181, Melbourne, Australia.
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36
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Abstract
The generation of a peripheral T-cell pool is essential for normal immune system function. CD4+ and CD8+ T cells are produced most efficiently in the thymus, which provides a complexity of discrete cellular microenvironments. Specialized stromal cells, that make up such microenvironments, influence each stage in the maturation programme of immature T-cell precursors. Progress has recently been made in elucidating events that regulate the development of intrathymic microenvironments, as well as mechanisms of thymocyte differentiation. It is becoming increasingly clear that the generation and maintenance of thymic environments that are capable of supporting efficient T-cell development, requires complex interplay between lymphoid and stromal compartments of the thymus.
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Affiliation(s)
- G Anderson
- Department of Anatomy, MRC Centre for Immune Regulation, University of Birmingham, Edgbaston, UK.
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37
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Abstract
The earliest T cells homing to the thymus (CD3-CD4loCD8-) express CD117 (c-kit), CD43 (leukosialin), and the integrins CD11a (alphaL), CD11b (alphaM), CD29 (beta1), CD49f (alpha6), and CD44. Using reagents specific for CD44 variant isoforms (CD44v), we demonstrated that CD44v were expressed on virtually all early thymocytes,whereas cells carrying only the standard molecule (CD44s, not containing any variant domains), which is ubiquitously found on mature lymphocytes later, are very sparse. The expression of CD44v was closely correlated with CD43 and CD117 and was restricted to the CD3-CD4loCD8- stage. CD44v were detected on lymphocyte progenitor populations in the fetal blood, liver, thymus and spleen, as well as in the adult bone marrow. Functional studies demonstrated that only cells expressing CD44v from fetal liver and adult bone marrow could efficiently populate fetal thymic stroma and develop into mature T cells. In fetal thymic organ cultures anti-CD44v antibodies specifically blocked thymocyte development. We also present evidence that CD44v were required for the initial interaction of hematopoietic progenitor cells with the thymic stroma. Our data imply that CD44v are not only a useful marker for hematopoietic progenitors, but also play a functional role in the initiation of thymocyte development.
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Affiliation(s)
- C Schwärzler
- Basel Institute for Immunology, Basel, Switzerland
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38
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Owen JJ, McLoughlin DE, Suniara RK, Jenkinson EJ. The role of mesenchyme in thymus development. Curr Top Microbiol Immunol 2001; 251:133-7. [PMID: 11036768 DOI: 10.1007/978-3-642-57276-0_17] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
We have reviewed the evidence that thymic mesenchymal cells and their progeny thymic fibroblasts play an important role in early T-cell development. Although it is possible that mesenchyme plays an inductive role in thymic epithelial morphogenesis, we have presented evidence to suggest that there is a direct effect of mesenchyme and fibroblasts on T-cell development. Moreover the association of these cell types with an ECM raises the possibility that the latter might be important in integrin and/or cytokine presentation especially during the CD4(-)8- phase of T-cell development.
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Affiliation(s)
- J J Owen
- Department of Anatomy, Medical School, University of Birmingham, Edgbaston, UK
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39
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Abstract
The thymus is an endocrine organ. A unified, physiological concept of humoral regulation of the immune response emerged in the last three decades. The thymus is the primary major site of production of immunocompetent T-lymphocytes from their haematopoietic stem cells. The thymus provides a superior humoral microenvironment for the development of immunocompetent T-lymphocytes. Although yolk sac derived pre-T stem cells enter the thymus using a homing receptor, the immigration process requires also secretion of a peptide, called thymotaxin by the cells of the reticulo-epithelial (RE) network. This complex process requires direct cell to cell, receptor based interactions, as well as in situ paracrine information via the numerous cytokines and thymic hormones produced by the RE cells of thymic microenvironment. Thymic hormones induce in situ T-lymphocyte marker differentiation, expression and functions. These polypeptide hormones have also been shown by means of immunocytochemistry to localise in the RE cells of the thymic cellular microenvironment. Based on the complexity of the intrathymic maturation sequence of T-lymphocytes and the increasing numbers of T-lymphocyte subpopulations that are being identified, it would be surprising if a single thymic humoral factor could control all of the molecular steps and cell populations involved. Rather, it would appear that the control of intrathymic T-lymphocyte maturation and functional maturation involves a complex number of thymic-specific factors and other molecules that rigidly control the intermediary steps in the differentiation process. Thymosin fraction 5 (TF5) and its component polypeptides influence a variety of lymphocyte properties including cyclic nucleotide levels, migration inhibitory factor production, T-dependent antibody production and expression of certain surface maturation/differentiation markers. Recently, thymic hormones, mostly thymosins have been employed not only in neoplasms' early detection but also in clinical trials to strengthen the effects of immunomodulators in immunodeficiencies, autoimmune diseases and neoplastic malignancies. Combined chemoimmunotherapeutical antineoplastic treatment seems to be useful. Generally, haematopoietic toxicity of every chemotherapeutical clinical trial can be reduced significantly by the immunotherapy, compared to 50% in patients treated with chemotherapy alone.
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Affiliation(s)
- B Bodey
- Childrens Center for Cancer and Blood Diseases, Childrens Hospital Los Angeles, Los Angeles, CA, USA.
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40
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Anderson G, Harman BC, Hare KJ, Jenkinson EJ. Microenvironmental regulation of T cell development in the thymus. Semin Immunol 2000; 12:457-64. [PMID: 11085178 DOI: 10.1006/smim.2000.0260] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
T cell development in the thymus occurs through a series of events beginning with thymic colonization by migrant precursors and ending with the emigration of functionally competent CD4+ and CD8+ T cells to the periphery. It is well accepted that signals through the pre-T cell receptor (pre-TCR) and alpha-beta TCR (alphabetaTCR) complex play pivotal roles in the maturation of CD4-8- and CD4+8+ thymocytes, respectively. It is clear that stromal cells constituting the thymic microenvironment provide non-TCR-mediated interactions which are essential for several developmental events. Examples of such will be discussed here in relation to early and late events in T cell development.
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Affiliation(s)
- G Anderson
- Department of Anatomy, MRC Centre for Immune Regulation Medical School, University of Birmingham, UK.
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41
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Abstract
In the mature thymus, thymocyte maturation depends on interactions with different thymic epithelial subtypes in a three-dimensional thymic architecture. However, the molecular mechanisms that generate these epithelial subtypes are not well understood. Evidence is accumulating that during fetal thymus development, epithelial cells differentiate by successive interactions with differentiating thymocytes. This review presents fetal thymus development as a process of organogenesis, the main function of which is to promote thymic epithelial cell differentiation and the generation of a functional thymic microenvironment. In this model, endoderm-derived epithelial cells are the driving force in generating the thymic primordium, with hematopoietic cells providing later signals that organize and pattern the developing thymus.
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Affiliation(s)
- N R Manley
- Institute of Molecular Medicine and Genetics and Department of Pediatrics, Medical College of Georgia, Augusta 30912, USA
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42
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Petrie HT, Tourigny M, Burtrum DB, Livak F. Precursor thymocyte proliferation and differentiation are controlled by signals unrelated to the pre-TCR. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:3094-8. [PMID: 10975821 DOI: 10.4049/jimmunol.165.6.3094] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In-frame rearrangement of the TCR-beta locus and expression of the pre-TCR are compulsory for the production of CD4+8+ thymocytes from CD4-8- precursors. Signals delivered via the pre-TCR are thought to induce the differentiation process as well as the extensive proliferation that accompanies this transition. However, it is equally possible that pre-TCR expression is required for the success of this transition, but does not play a direct role in the inductive process. In the present manuscript we examine this possibility using a variety of normal and genetically modified mouse models. Our evidence shows that differentiation and mitogenesis can both occur independently of pre-TCR expression. However, these processes are absolutely dependent on the presence of normal thymic architecture and cellular composition. These findings are consistent with a checkpoint role for the pre-TCR in regulating the divergence of survival and cell death fates at the CD4-8- to CD4+8+ transition. Further, our data suggest that precursor thymocyte differentiation is induced by other, probably ubiquitous, mechanisms that require the presence of normal thymic cellularity, composition, and architecture.
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MESH Headings
- Animals
- Cell Death/genetics
- Cell Death/immunology
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Division/genetics
- Cell Division/immunology
- Cell Survival/genetics
- Cell Survival/immunology
- Gene Expression Regulation/immunology
- Gene Rearrangement, beta-Chain T-Cell Antigen Receptor
- Genes, T-Cell Receptor beta
- Lymphocyte Activation/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mitosis/genetics
- Mitosis/immunology
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/deficiency
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/physiology
- Signal Transduction/genetics
- Signal Transduction/immunology
- Stem Cells/immunology
- Stem Cells/metabolism
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
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Affiliation(s)
- H T Petrie
- Immunology Program, Memorial Sloan-Kettering Cancer Center, and Joan and Sanford Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA.
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43
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Su DM, Manley NR. Hoxa3 and pax1 transcription factors regulate the ability of fetal thymic epithelial cells to promote thymocyte development. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:5753-60. [PMID: 10820253 DOI: 10.4049/jimmunol.164.11.5753] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Thymocyte maturation into T cells depends on interactions between thymocytes and thymic epithelial cells. In this study, we show that mutations in two transcription factors, Hoxa3 and Pax1, act synergistically to cause defective thymic epithelial cell development, resulting in thymic ectopia and hypoplasia. Hoxa3+/-Pax1-/- compound mutant mice exhibited more severe thymus defects than Pax1-/- single mutants. Fetal liver adoptive transfer experiments revealed that the defect resided in radio-resistant stromal cells and not in hematopoietic cells. Compound mutants have fewer MHC class II+ epithelial cells, and the level of MHC expression detected was lower. Thymic epithelial cells in these mutants have reduced ability to promote thymocyte development, causing a specific block in thymocyte maturation at an early stage that resulted in a dramatic reduction in the number of CD4+8+ thymocytes. This phenotype was accompanied by increased apoptosis of CD4+8+ thymocytes and their immediate precursors, CD44-25-(CD3-4-8-) cells. Our results identify a transcriptional regulatory pathway required for thymic epithelial cell development and define multiple roles for epithelial cell regulation of thymocyte maturation at the CD4-8- to CD4+8+ transition.
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MESH Headings
- Adjuvants, Immunologic/genetics
- Adjuvants, Immunologic/physiology
- Animals
- Antigens, CD/biosynthesis
- Antigens, Differentiation, T-Lymphocyte/biosynthesis
- CD4-CD8 Ratio
- Cell Death/genetics
- Cell Death/immunology
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Embryonic and Fetal Development/genetics
- Embryonic and Fetal Development/immunology
- Epithelial Cells/immunology
- Epithelial Cells/metabolism
- Gene Deletion
- Histocompatibility Antigens Class II/biosynthesis
- Homeodomain Proteins/genetics
- Homeodomain Proteins/physiology
- Lectins, C-Type
- Lymphocyte Depletion
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Paired Box Transcription Factors
- Phenotype
- Receptors, Antigen, T-Cell/biosynthesis
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/embryology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Transcription Factors/genetics
- Transcription Factors/physiology
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Affiliation(s)
- D M Su
- Institute of Molecular Medicine and Genetics and Department of Pediatrics, Medical College of Georgia, Augusta, GA 30912, USA.
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44
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Abstract
We show that the mesenchymal cells that surround the 12-d mouse embryo thymus are necessary for T cell differentiation. Thus, epithelial lobes with attached mesenchyme generate all T cell populations in vitro, whereas lobes from which mesenchyme has been removed show poor lymphopoiesis with few cells progressing beyond the CD4(-)CD8(-) stage of development. Interestingly, thymic mesenchyme is derived from neural crest cells, and extirpation of the region of the neural crest involved results in impaired thymic development and craniofacial abnormalities similar to the group of clinical defects found in the DiGeorge syndrome. Previous studies have suggested an inductive effect of mesenchyme on thymic epithelial morphogenesis. However, we have found that mesenchyme-derived fibroblasts are still required for early T cell development in the presence of mature epithelial cells, and hence mesenchyme might have a direct role in lymphopoiesis. We provide an anatomical basis for the role of mesenchyme by showing that mesenchymal cells migrate into the epithelial thymus to establish a network of fibroblasts and associated extracellular matrix. We propose that the latter might be important for T cell development through integrin and/or cytokine interactions with immature thymocytes.
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Affiliation(s)
- R K Suniara
- Department of Anatomy, Division of Immunity and Infection, Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
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45
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Norment AM, Bogatzki LY, Gantner BN, Bevan MJ. Murine CCR9, a chemokine receptor for thymus-expressed chemokine that is up-regulated following pre-TCR signaling. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 164:639-48. [PMID: 10623805 DOI: 10.4049/jimmunol.164.2.639] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Chemokines are likely to play an important role in regulating the trafficking of developing T cells within the thymus. By using anti-CD3varepsilon treatment of recombinase-activating gene 2 (Rag2-/-) mice to mimic pre-TCR signaling and drive thymocyte development to the double positive stage, we have identified murine GPR-9-6 as a chemokine receptor whose expression is strongly induced following pre-TCR signaling. GPR-9-6 mRNA is present at high levels in the thymus, and by RT-PCR analysis its expression is induced as normal thymocytes undergo the double negative to double positive transition. Furthermore we show that TECK (thymus-expressed chemokine), a chemokine produced by thymic medullary dendritic cells, is a functional ligand for GPR-9-6. TECK specifically induces a calcium flux and chemotaxis of GPR-9-6-transfected cells. In addition, TECK stimulates the migration of normal double positive thymocytes, as well as Rag2-/- thymocytes following anti-CD3varepsilon treatment. Hence, GPR-9-6 has been designated as CC chemokine receptor 9 (CCR9). Our results suggest that TECK delivers signals through CCR9 important for the navigation of developing thymocytes.
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MESH Headings
- Animals
- Antibodies, Monoclonal/pharmacology
- Calcium/metabolism
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Line
- Cell Movement/immunology
- Chemokines, CC/metabolism
- Chemokines, CC/physiology
- Chemotaxis, Leukocyte/immunology
- DNA-Binding Proteins/deficiency
- DNA-Binding Proteins/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/physiology
- Receptors, CCR
- Receptors, Chemokine/biosynthesis
- Receptors, Chemokine/genetics
- Signal Transduction/immunology
- Stem Cells/metabolism
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/metabolism
- Transfection
- Up-Regulation/immunology
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Affiliation(s)
- A M Norment
- Department of Immunology, Howard Hughes Medical Institute, University of Washington, Seattle WA 98195, USA.
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46
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Inoue M, Fujii Y, Okumura M, Miyoshi S, Shiono H, Fukuhara K, Kadota Y, Matsuda H. T-cell development in human thymoma. Pathol Res Pract 1999; 195:541-7. [PMID: 10483584 DOI: 10.1016/s0344-0338(99)80003-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Human thymoma is derived from thymic epithelial cells and often associated with a large number of cortical thymocytes. Since thymic epithelial cells play key roles in T-cell development in the normal thymus, we hypothesized that the neoplastic epithelial cells of thymoma may support T-cell differentiation. We attempted to reconstitute the T-cell development in vitro by using neoplastic epithelial cells isolated from thymoma. CD34, a stem cell marker, was expressed on a proportion of CD4-CD8- cells in thymoma. These CD34+CD4-CD8- cells also expressed both IL-7R alpha-chain and common gamma-chain. Purified CD4-CD8- cells from thymomas were cultured with the neoplastic epithelial cells, and their differentiation into CD4+CD8+ cells via CD4 single positive intermediates was observed within 9 days' co-culture in the presence of recombinant IL-7. The CD34+CD4-CD8- cells purified from a normal thymus also differentiated to CD4+CD8+ cells in an allogeneic co-culture with the neoplastic epithelial cells of thymoma. In addition, a pleural dissemination from thymoma contained a large amount of cortical thymocytes. These results suggest that the neoplastic epithelial cells retain the function of thymic epithelium and can support T-cell development in thymomas.
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Affiliation(s)
- M Inoue
- First Department of Surgery, Osaka University Medical School, Japan
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47
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Wiest DL, Berger MA, Carleton M. Control of early thymocyte development by the pre-T cell receptor complex: A receptor without a ligand? Semin Immunol 1999; 11:251-62. [PMID: 10441211 DOI: 10.1006/smim.1999.0181] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Beta-selection refers to a developmental checkpoint linking thymocyte survival to the outcome of antigen receptor gene rearrangement. Immature thymocytes that productively rear-range the gene segments of the TCRbeta locus undergo proliferative expansion and mature to the CD4(+)CD8(+)stage; those failing to do so die by apoptosis. How are these precursor cells alerted that TCRbeta rearrangement has been productive? While it is clear that this process involves signals transduced by a surrogate form of the TCR termed the pre-TCR, it remains unclear how pre-TCR signals are triggered. In this review, we will discuss the implications of recent experimental attempts to address this issue, as well as how pre-TCR activation is linked to the changes in gene expression that underlie thymocyte development.
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Affiliation(s)
- D L Wiest
- Division of Basic Sciences, Immunobiology Working Group, Fox Chase Cancer Center, 7701 Burholme Ave., Philadelphia, PA 19111, USA
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48
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Owen JJ, McLoughlin DE, Suniara RK, Jenkinson EJ. Cellular and matrix interactions during the development of T lymphocytes. Braz J Med Biol Res 1999; 32:551-5. [PMID: 10412566 DOI: 10.1590/s0100-879x1999000500008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The thymus contains an extensive extracellular matrix. Although thymocytes express integrins capable of binding to matrix molecules, the functional significance of the matrix for T cell development is uncertain. We have shown that the matrix is associated with thymic fibroblasts which are required for the CD44+ CD25+ stage of double negative (CD4-8-) thymocyte development. The survival of cells at this stage is dependent on IL-7 and we propose that the role of fibroblasts is to present, via the matrix, IL-7 to developing T cells.
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Affiliation(s)
- J J Owen
- Department of Anatomy, Medical School, University of Birmingham, Edgbaston, UK.
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49
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Wilkinson B, Owen JJT, Jenkinson EJ. Factors Regulating Stem Cell Recruitment to the Fetal Thymus. THE JOURNAL OF IMMUNOLOGY 1999. [DOI: 10.4049/jimmunol.162.7.3873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Colonization of the thymic rudiment during development is initiated before vascularization so that hemopoietic precursors must leave the pharyngeal vessels and migrate through the perithymic mesenchyme to reach the thymus, suggesting that they may be responding to a gradient of chemoattractant factors. We report that diffusible chemoattractants are produced by MHC class II+ epithelial cells of the fetal thymus, and that the response of precursors to these factors is mediated via a G protein-coupled receptor, consistent with factors being members of the chemokine family. Indeed, a number of chemokine receptors are expressed by thymic precursors, and several chemokines are also expressed by thymic epithelial cells. However, these chemokines are also expressed in a tissue that is unable to attract precursors, although the thymus expressed chemokine, TECK, is expressed at higher levels in thymic epithelial cells and we show that it has chemotactic activity for isolated thymic precursors. Neutralizing Ab to TECK, however, did not prevent thymus recolonization by T cell precursors, suggesting that other novel chemokines might be involved in this process. In addition, we provide evidence for the involvement of matrix metalloproteinases in chemoattractant-mediated T cell precursor recruitment to the thymus during embryogenesis.
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Affiliation(s)
- B. Wilkinson
- Department of Anatomy, The Medical School, University of Birmingham, Birmingham, United Kingdom
| | - J. J. T. Owen
- Department of Anatomy, The Medical School, University of Birmingham, Birmingham, United Kingdom
| | - E. J. Jenkinson
- Department of Anatomy, The Medical School, University of Birmingham, Birmingham, United Kingdom
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50
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Upregulated Expression of Fibronectin Receptors Underlines the Adhesive Capability of Thymocytes to Thymic Epithelial Cells During the Early Stages of Differentiation: Lessons From Sublethally Irradiated Mice. Blood 1999. [DOI: 10.1182/blood.v93.3.974.403k19_974_990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A 250-cGy whole-body γ-radiation dose was used to induce thymus regression in mice, and to study the expression and function of extracellular matrix (ECM) receptors in distinct thymocyte subsets emerging during repopulation of the organ. The onset of regeneration was detected from day 2 to 3 postirradiation (P-Ir), when a remarkable increase in the absolute counts of CD3−CD25hiCD44+ and CD3−CD25in/hiCD44−cells occurred. Enhanced expression of L-selectin, 4, and 5 integrin chains (L-selhi 4hi5hi) was also exhibited by these cells. This pattern of expression was maintained until the CD4+CD8+ (DP) young stage was achieved. Afterward, there was a general downregulation of these ECM receptors in DP as well as in CD4+ or CD8+ single positive (SP) thymocytes (L-selin 4in5in). In some recently generated SP cells, 4 expression was downregulated before the 5 chain, and L-selectin was upregulated in half of more mature cells. The expression of the 6 integrin chain was downregulated only in maturing CD4+cells. Importantly, the increased expression of L-selectin and 4 and 5 chains in thymocytes was strongly correlated with their adhesiveness to thymic epithelial cells (TEC) in vitro. Blocking experiments with monoclonal antibody or peptides showed the following: (1) that the LDV rather than the REDV cell attachment motif in the IIIC segment of fibronectin is targeted by the 4 integrin during thymocyte/TEC adhesion; (2) that the RGD motif of the 120-kD fragment of fibronectin, a target for 5 integrin, has a secondary role in this adhesion; and (3) that the YIGSR cell attachment motif of the β1 chain of laminin/merosin recognized by a nonintegrin receptor is not used for thymocyte adherence. In conclusion, our results show that an upregulated set of receptors endows CD25+ precursors and cells up to the young DP stage with a high capability of interacting with thymic ECM components.
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