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Manoharan Valerio M, Arana K, Guan J, Chan SW, Yang X, Kurd N, Lee A, Shastri N, Coscoy L, Robey EA. The promiscuous development of an unconventional Qa1b-restricted T cell population. Front Immunol 2023; 14:1250316. [PMID: 38022509 PMCID: PMC10644506 DOI: 10.3389/fimmu.2023.1250316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 10/06/2023] [Indexed: 12/01/2023] Open
Abstract
MHC-E restricted CD8 T cells show promise in vaccine settings, but their development and specificity remain poorly understood. Here we focus on a CD8 T cell population reactive to a self-peptide (FL9) bound to mouse MHC-E (Qa-1b) that is presented in response to loss of the MHC I processing enzyme ERAAP, termed QFL T cells. We find that mature QFL thymocytes are predominantly CD8αβ+CD4-, show signs of agonist selection, and give rise to both CD8αα and CD8αβ intraepithelial lymphocytes (IEL), as well as memory phenotype CD8αβ T cells. QFL T cells require the MHC I subunit β-2 microglobulin (β2m), but do not require Qa1b or classical MHC I for positive selection. However, QFL thymocytes do require Qa1b for agonist selection and full functionality. Our data highlight the relaxed requirements for positive selection of an MHC-E restricted T cell population and suggest a CD8αβ+CD4- pathway for development of CD8αα IELs.
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Affiliation(s)
- Michael Manoharan Valerio
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, United States
| | - Kathya Arana
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, United States
| | - Jian Guan
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Shiao Wei Chan
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, United States
| | - Xiaokun Yang
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, United States
| | - Nadia Kurd
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, United States
| | - Angus Lee
- Gene Targeting Facility Cancer Research Laboratory, University of California Berkeley, Berkeley, CA, United States
| | - Nilabh Shastri
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Laurent Coscoy
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, United States
| | - Ellen A. Robey
- Division of Immunology and Molecular Medicine, Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, United States
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Joannou K, Baldwin TA. Destined for the intestine: thymic selection of TCRαβ CD8αα intestinal intraepithelial lymphocytes. Clin Exp Immunol 2023; 213:67-75. [PMID: 37137518 PMCID: PMC10324546 DOI: 10.1093/cei/uxad049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 03/22/2023] [Accepted: 04/30/2023] [Indexed: 05/05/2023] Open
Abstract
The immune system is composed of a variety of different T-cell lineages distributed through both secondary lymphoid tissue and non-lymphoid tissue. The intestinal epithelium is a critical barrier surface that contains numerous intraepithelial lymphocytes that aid in maintaining homeostasis at that barrier. This review focuses on T-cell receptor αβ (TCRαβ) CD8αα intraepithelial lymphocytes, and how recent advances in the field clarify how this unique T-cell subset is selected, matures, and functions in the intestines. We consider how the available evidence reveals a story of ontogeny starting from agonist selection of T cells in the thymus and finishing through the specific signaling environment of the intestinal epithelium. We conclude with how this story raises further key questions about the development of different ontogenic waves of TCRαβ CD8αα IEL and their importance for intestinal epithelial homeostasis.
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Affiliation(s)
- Kevin Joannou
- Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Troy A Baldwin
- Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
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3
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Heimli M, Flåm ST, Hjorthaug HS, Trinh D, Frisk M, Dumont KA, Ribarska T, Tekpli X, Saare M, Lie BA. Multimodal human thymic profiling reveals trajectories and cellular milieu for T agonist selection. Front Immunol 2023; 13:1092028. [PMID: 36741401 PMCID: PMC9895842 DOI: 10.3389/fimmu.2022.1092028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 12/22/2022] [Indexed: 01/22/2023] Open
Abstract
To prevent autoimmunity, thymocytes expressing self-reactive T cell receptors (TCRs) are negatively selected, however, divergence into tolerogenic, agonist selected lineages represent an alternative fate. As thymocyte development, selection, and lineage choices are dependent on spatial context and cell-to-cell interactions, we have performed Cellular Indexing of Transcriptomes and Epitopes by sequencing (CITE-seq) and spatial transcriptomics on paediatric human thymus. Thymocytes expressing markers of strong TCR signalling diverged from the conventional developmental trajectory prior to CD4+ or CD8+ lineage commitment, while markers of different agonist selected T cell populations (CD8αα(I), CD8αα(II), T(agonist), Treg(diff), and Treg) exhibited variable timing of induction. Expression profiles of chemokines and co-stimulatory molecules, together with spatial localisation, supported that dendritic cells, B cells, and stromal cells contribute to agonist selection, with different subsets influencing thymocytes at specific developmental stages within distinct spatial niches. Understanding factors influencing agonist T cells is needed to benefit from their immunoregulatory effects in clinical use.
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Affiliation(s)
- Marte Heimli
- Department of Medical Genetics, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Siri Tennebø Flåm
- Department of Medical Genetics, Oslo University Hospital, University of Oslo, Oslo, Norway
| | | | - Don Trinh
- Department of Pathology, Oslo University Hospital, Oslo, Norway
| | - Michael Frisk
- Institute for Experimental Medical Research, Oslo University Hospital, University of Oslo, Oslo, Norway,KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Karl-Andreas Dumont
- Department of Cardiothoracic Surgery, Oslo University Hospital, Oslo, Norway
| | - Teodora Ribarska
- Department of Medical Genetics, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Xavier Tekpli
- Department of Medical Genetics, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Mario Saare
- Department of Medical Genetics, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Benedicte Alexandra Lie
- Department of Medical Genetics, Oslo University Hospital, University of Oslo, Oslo, Norway,*Correspondence: Benedicte Alexandra Lie,
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Antigen-presenting T cells provide critical B7 co-stimulation for thymic iNKT cell development via CD28-dependent trogocytosis. Cell Rep 2022; 41:111731. [PMID: 36450247 PMCID: PMC9805342 DOI: 10.1016/j.celrep.2022.111731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 10/03/2022] [Accepted: 11/04/2022] [Indexed: 12/02/2022] Open
Abstract
Invariant natural killer T (iNKT) cell development in the thymus depends on T cell receptor recognition of CD1d ligand on CD4/CD8 double-positive thymocytes. We previously reported that B7-CD28 co-stimulation is required for thymic iNKT cell development, but the cellular and molecular mechanisms underlying this co-stimulatory requirement are not understood. Here we report that CD28 expression on CD1d-expressing antigen-presenting T cells is required for thymic iNKT cell development. Mechanistically, antigen-presenting T cells provide co-stimulation through an unconventional mechanism, acquiring B7 molecules via CD28-dependent trogocytosis from B7-expressing thymic epithelial cells, dendritic cells, and B cells and providing critical B7 co-stimulation to developing iNKT cells. Thus, the present study demonstrates a mechanism of B7 co-stimulation in thymic T cell development by antigen-presenting T cells.
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