Abstract
T cell Ig and ITIM domain (TIGIT) is a newly identified receptor expressed on T cells that binds to CD155 on the dendritic cell surface, driving them to a more tolerogenic phenotype. Given that TIGIT contains an ITIM motif in its intracellular domain and considering the potential importance of the TIGIT/CD226 pathway in human autoimmune disease, we investigated the specific role of TIGIT in human CD4(+) T cells. Using an agonistic anti-TIGIT mAb, we demonstrate a direct inhibitory effect on T cell proliferation with a decrease in expression of T-bet, GATA3, IFN regulatory factor 4, and retinoic acid-related orphan receptor c with inhibition of cytokine production, predominantly IFN-γ. Knockdown of TIGIT expression by short hairpin RNA resulted in an increase of both T-bet and IFN-γ mRNA and protein expression with concomitant decrease in IL-10 expression. Increases in IFN-γ with TIGIT knockdown could be overcome by blocking CD226 signaling, indicating that TIGIT exerts immunosuppressive effects by competing with CD226 for the same CD155 ligand. These data demonstrate that TIGIT can inhibit T cell functions by competing with CD226 and can also directly inhibit T cells in a T cell-intrinsic manner. Our results provide evidence for a novel role of this alternative costimulatory pathway in regulating human T cell responses associated with autoimmune disease.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Antibodies, Monoclonal / pharmacology
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Antigens, Differentiation, T-Lymphocyte / genetics
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Antigens, Differentiation, T-Lymphocyte / immunology*
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Antigens, Differentiation, T-Lymphocyte / metabolism
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CD4-Positive T-Lymphocytes / cytology
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CD4-Positive T-Lymphocytes / immunology*
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CD4-Positive T-Lymphocytes / metabolism
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Cell Communication
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Cell Proliferation / drug effects
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Cells, Cultured
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Cytokines / biosynthesis
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Cytokines / immunology
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Dendritic Cells / cytology
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Dendritic Cells / immunology*
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Dendritic Cells / metabolism
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GATA3 Transcription Factor / genetics
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GATA3 Transcription Factor / immunology
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Gene Expression Regulation
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Humans
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Immune Tolerance / genetics
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Immune Tolerance / immunology*
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RNA, Small Interfering / genetics
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Receptors, Immunologic / genetics
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Receptors, Immunologic / immunology*
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Receptors, Immunologic / metabolism
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Receptors, Virus / genetics
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Receptors, Virus / immunology*
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Receptors, Virus / metabolism
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Signal Transduction
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T-Box Domain Proteins / genetics
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T-Box Domain Proteins / immunology
Substances
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Antibodies, Monoclonal
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Antigens, Differentiation, T-Lymphocyte
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CD226 antigen
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Cytokines
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GATA3 Transcription Factor
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GATA3 protein, human
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RNA, Small Interfering
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Receptors, Immunologic
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Receptors, Virus
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T-Box Domain Proteins
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T-box transcription factor TBX21
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TIGIT protein, human
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poliovirus receptor