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Protschka M, Di Placido D, Moore PF, Büttner M, Alber G, Eschke M. Canine peripheral non-conventional TCRαβ + CD4 -CD8α - double-negative T cells show T helper 2-like and regulatory properties. Front Immunol 2024; 15:1400550. [PMID: 38835756 PMCID: PMC11148280 DOI: 10.3389/fimmu.2024.1400550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Accepted: 04/29/2024] [Indexed: 06/06/2024] Open
Abstract
The dog is an important companion animal and also serves as model species for human diseases. Given the central role of T cells in immune responses, a basic understanding of canine conventional T cell receptor (TCR)αβ+ T cells, comprising CD4+ single-positive (sp) T helper (Th) and CD8α+ sp cytotoxic T cell subsets, is available. However, characterization of canine non-conventional TCRαβ+ CD4+CD8α+ double-positive (dp) and TCRαβ+ CD4-CD8α- double-negative (dn) T cells is limited. In this study, we performed a comprehensive analysis of canine dp and dn T cells in comparison with their conventional counterparts. TCRαβ+ T cells from peripheral blood of healthy dogs were sorted according to their CD4/CD8α phenotype into four populations (i.e. CD4+ sp, CD8α+ sp, dp, and dn) and selected surface markers, transcription factors and effector molecules were analyzed ex vivo and after in vitro stimulation by RT-qPCR. Novel characteristics of canine dp T cells were identified, expanding the previously characterized Th1-like phenotype to Th17-like and Th2-like properties. Overall, mRNA expression of various Th cell-associated cytokines (i.e. IFNG, IL17A, IL4, IL13) in dp T cells upon stimulation highlights their versatile immunological potential. Furthermore, we demonstrated that the CD4-CD8α- dn phenotype is stable during in vitro stimulation. Strikingly, dn T cells were found to express highest mRNA levels of type 2 effector cytokines (IL4, IL5, and IL13) upon stimulation. Their strong ability to produce IL-4 was confirmed at the protein level. Upon stimulation, the percentage of IL-4-producing cells was even higher in the non-conventional dn than in the conventional CD4+ sp population. Constitutive transcription of IL1RL1 (encoding IL-33Rα) further supports Th2-like properties within the dn T cell population. These data point to a role of dn T cells in type 2 immunity. In addition, the high potential of dn T cells to transcribe the gene encoding the co-inhibitory receptor CTLA-4 and to produce the inhibitory cytokine IL-10 indicates putative immunosuppressive capacity of this population. In summary, this study reveals important novel aspects of canine non-conventional T cells providing the basis for further studies on their effector and/or regulatory functions to elucidate their role in health and disease.
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MESH Headings
- Animals
- Dogs
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Th2 Cells/immunology
- CD8 Antigens/metabolism
- CD8 Antigens/immunology
- Cytokines/metabolism
- CD4 Antigens/metabolism
- CD4 Antigens/immunology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- T-Lymphocytes, Regulatory/immunology
- T-Lymphocytes, Regulatory/metabolism
- Immunophenotyping
- Male
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Affiliation(s)
- Martina Protschka
- Institute of Immunology, Center for Biotechnology and Biomedicine, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Daniela Di Placido
- Institute of Immunology, Center for Biotechnology and Biomedicine, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Peter F Moore
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Mathias Büttner
- Institute of Immunology, Center for Biotechnology and Biomedicine, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Gottfried Alber
- Institute of Immunology, Center for Biotechnology and Biomedicine, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
| | - Maria Eschke
- Institute of Immunology, Center for Biotechnology and Biomedicine, Faculty of Veterinary Medicine, Leipzig University, Leipzig, Germany
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Rabiger FV, Rothe K, von Buttlar H, Bismarck D, Büttner M, Moore PF, Eschke M, Alber G. Distinct Features of Canine Non-conventional CD4 -CD8α - Double-Negative TCRαβ + vs. TCRγδ + T Cells. Front Immunol 2019; 10:2748. [PMID: 31824515 PMCID: PMC6883510 DOI: 10.3389/fimmu.2019.02748] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 11/11/2019] [Indexed: 01/01/2023] Open
Abstract
The role of conventional TCRαβ+CD4+ or TCRαβ+CD8α+ single-positive (sp) T lymphocytes in adaptive immunity is well-recognized. However, non-conventional T cells expressing TCRαβ or TCRγδ but lacking CD4 and CD8α expression [i.e., CD4−CD8α− double-negative (dn) T cells] are thought to play a role at the interface between the innate and adaptive immune system. Dn T cells are frequent in swine, cattle or sheep and predominantly express TCRγδ. In contrast, TCRγδ+ T cells are rare in dogs. In this study, we identified a high proportion of canine dn T cells in the TCRαβ+ T cell population of PBMC, lymphatic and non-lymphatic organs. In PBMC, the frequency of this T cell subpopulation made up one third of the frequency of TCRαβ+CD4+ sp, and almost half of the frequency of TCRαβ+CD8α+ sp T cells (i.e., ~15% of all TCRαβ+ T cells). Among TCRαβ+CD4−CD8α− dn T cells of PBMC and tissues, FoxP3+ cells were identified indicating regulatory potential of this T cell subset. 80% of peripheral blood FoxP3+TCRαβ+CD4−CD8α− dn T cells co-expressed CD25, and, interestingly, also the FoxP3-negative TCRαβ+CD4−CD8α− dn T cells comprised ~34% CD25+ cells. Some of the FoxP3-positive TCRαβ+CD4−CD8α− dn T cells co-expressed GATA-3 suggesting stable function of regulatory T cells. The frequency of GATA-3 expression by FoxP3−TCRαβ+CD4−CD8α− dn T cells was even higher as compared with TCRαβ+CD4+ sp T cells (20.6% vs. 11.9%). Albeit lacking FoxP3 and CD25 expression, TCRγδ+CD4−CD8α− dn T cells also expressed substantial proportions of GATA-3. In addition, TCRαβ+CD4−CD8α− dn T cells produced IFN-γ and IL-17A upon stimulation. T-bet and granzyme B were only weakly expressed by both dn T cell subsets. In conclusion, this study identifies two dn T cell subsets in the dog: (i) a large (~7.5% in Peyer's patches, ~15% in lung) population of TCRαβ+CD4−CD8α− dn T cells with subpopulations thereof showing an activated phenotype, high expression of FoxP3 or GATA-3 as well as production of IFN-γ or IL-17A and (ii) a small TCRγδ+CD4−CD8α− dn T cell subset also expressing GATA-3 without production of IFN-γ or IL-17A. It will be exciting to unravel the function of each subset during immune homeostasis and diseases of dogs.
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Affiliation(s)
- Friederike V Rabiger
- Institute of Immunology/Molecular Pathogenesis, Center for Biotechnology and Biomedicine, College of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - Kathrin Rothe
- Institute of Immunology/Molecular Pathogenesis, Center for Biotechnology and Biomedicine, College of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - Heiner von Buttlar
- Institute of Immunology/Molecular Pathogenesis, Center for Biotechnology and Biomedicine, College of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - Doris Bismarck
- Institute of Immunology/Molecular Pathogenesis, Center for Biotechnology and Biomedicine, College of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - Mathias Büttner
- Institute of Immunology/Molecular Pathogenesis, Center for Biotechnology and Biomedicine, College of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - Peter F Moore
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Maria Eschke
- Institute of Immunology/Molecular Pathogenesis, Center for Biotechnology and Biomedicine, College of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - Gottfried Alber
- Institute of Immunology/Molecular Pathogenesis, Center for Biotechnology and Biomedicine, College of Veterinary Medicine, University of Leipzig, Leipzig, Germany
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