1
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Caruso B, Moran AE. Thymic expression of immune checkpoint molecules and their implication for response to immunotherapies. Trends Cancer 2023:S2405-8033(23)00063-8. [PMID: 37173189 DOI: 10.1016/j.trecan.2023.04.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/07/2023] [Accepted: 04/14/2023] [Indexed: 05/15/2023]
Abstract
The thymus is responsible for generating a diverse T cell repertoire that is tolerant to self, but capable of responding to various immunologic insults, including cancer. Checkpoint blockade has changed the face of cancer treatment by targeting inhibitory molecules, which are known to regulate peripheral T cell responses. However, these inhibitory molecules and their ligands are expressed during T cell development in the thymus. In this review, we describe the underappreciated role of checkpoint molecule expression during the formation of the T cell repertoire and detail the importance of inhibitory molecules in regulating T cell lineage commitment. Understanding how these molecules function in the thymus may inform therapeutic strategies for better patient outcomes.
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Affiliation(s)
- Breanna Caruso
- Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, OR, USA
| | - Amy E Moran
- Cell, Developmental and Cancer Biology, Oregon Health and Science University, Portland, OR, USA; Knight Cancer Institute, Oregon Health and Science University, Portland, OR, USA.
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2
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Wang Y, Wang P, Xu J. Phosphorylation: A Fast Switch For Checkpoint Signaling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1248:347-398. [PMID: 32185718 DOI: 10.1007/978-981-15-3266-5_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Checkpoint signaling involves a variety of upstream and downstream factors that participate in the regulation of checkpoint expression, activation, and degradation. During the process, phosphorylation plays a critical role. Phosphorylation is one of the most well-documented post-translational modifications of proteins. Of note, the importance of phosphorylation has been emphasized in aspects of cell activities, including proliferation, metabolism, and differentiation. Here we summarize how phosphorylation of specific molecules affects the immune activities with preference in tumor immunity. Of course, immune checkpoints are given extra attention in this book. There are many common pathways that are involved in signaling of different checkpoints. Some of them are integrated and presented as common activities in the early part of this chapter, especially those associated with PD-1/PD-L1 and CTLA-4, because investigations concerning them are particularly abundant and variant. Their distinct regulation is supplementarily discussed in their respective section. As for checkpoints that are so far not well explored, their related phosphorylation modulations are listed separately in the later part. We hope to provide a clear and systematic view of the phosphorylation-modulated immune signaling.
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Affiliation(s)
- Yiting Wang
- School of Medicine, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Ping Wang
- Shanghai Tenth People's Hospital of Tongji University, School of Medicine, School of Life Sciences and Technology, Tongji University Cancer Center, Tongji University, Shanghai, 200092, China
| | - Jie Xu
- Institutes of Biomedical Sciences, Zhongshan-Xuhui Hospital, Fudan University, Shanghai, 200032, China.
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3
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Mitsuiki N, Schwab C, Grimbacher B. What did we learn from CTLA-4 insufficiency on the human immune system? Immunol Rev 2019; 287:33-49. [PMID: 30565239 DOI: 10.1111/imr.12721] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Accepted: 09/16/2018] [Indexed: 02/07/2023]
Abstract
Cytotoxic-T-lymphocyte-antigen-4 (CTLA-4) is a negative immune regulator constitutively expressed on regulatory T (Treg) cells and upregulated on activated T cells. CTLA-4 inhibits T cell activation by various suppressive functions including competition with CD28, regulation of the inhibitory function of Treg cells, such as transendocytosis, and the control of adhesion and motility. Intrinsic CTLA-4 signaling has been controversially discussed, but so far no distinct signaling pathway has been identified. The CTLA-4-mediated Treg suppression plays an important role in the maintenance of peripheral tolerance and the prevention of autoimmune diseases. Human CTLA-4 insufficiency is caused by heterozygous germline mutations in CTLA4 and characterized by a complex immune dysregulation syndrome. Clinical studies on CTLA4 mutation carriers showed a reduced penetrance and variable expressivity, suggesting modifying factor(s). One hundred and forty-eight CTLA4 mutation carriers have been reported; patients showed hypogammaglobulinemia, recurrent infectious diseases, various autoimmune diseases, and lymphocytic infiltration into multiple organs. The CTLA-4 expression level in Treg cells was reduced, while the frequency of Treg cells was increased in CTLA-4-insufficient patients. The transendocytosis assay is a specific functional test for the assessment of newly identified CTLA4 gene variants. Immunoglobulin substitution, corticosteroids, immunosuppressive therapy, and targeted therapy such as with CTLA-4 fusion proteins and mechanistic target of rapamycin (mTOR) inhibitors were applied; patients with life-threatening, treatment-resistant symptoms underwent hematopoietic stem cell transplantation. The fact that in humans CTLA-4 insufficiency causes severe disease taught us that the amount of CTLA-4 molecules present in/on T cells matters for immune homeostasis. However, whether the pathology-causing activated T lymphocytes in CTLA-4-insufficient patients are antigen-specific is an unsolved question. CTLA-4, in addition, has a role in autoimmune diseases and cancer. Anti-CTLA-4 drugs are employed as checkpoint inhibitors to target various forms of cancer. Thus, clinical research on human CTLA-4 insufficiency might provide us a deeper understanding of the mechanism(s) of the CTLA-4 molecule and immune dysregulation disorders.
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Affiliation(s)
- Noriko Mitsuiki
- Center for Chronic Immunodeficiency (CCI), Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Charlotte Schwab
- Center for Chronic Immunodeficiency (CCI), Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Bodo Grimbacher
- Center for Chronic Immunodeficiency (CCI), Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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4
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Billard MJ, Gruver AL, Sempowski GD. Acute endotoxin-induced thymic atrophy is characterized by intrathymic inflammatory and wound healing responses. PLoS One 2011; 6:e17940. [PMID: 21437240 PMCID: PMC3060875 DOI: 10.1371/journal.pone.0017940] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 02/18/2011] [Indexed: 11/28/2022] Open
Abstract
Background Productive thymopoiesis is essential for a robust and healthy immune system.
Thymus unfortunately is acutely sensitive to stress resulting in involution
and decreased T cell production. Thymic involution is a complication of many
clinical settings, including infection, malnutrition, starvation, and
irradiation or immunosuppressive therapies. Systemic rises in
glucocorticoids and inflammatory cytokines are known to contribute to thymic
atrophy. Little is known, however, about intrathymic mechanisms that may
actively contribute to thymus atrophy or initiate thymic recovery following
stress events. Methodology/Principal Findings Phenotypic, histologic and transcriptome/pathway analysis of murine thymic
tissue during the early stages of endotoxemia-induced thymic involution was
performed to identify putative mechanisms that drive thymic involution
during stress. Thymus atrophy in this murine model was confirmed by
down-regulation of genes involved in T cell development, cell activation,
and cell cycle progression, correlating with observed phenotypic and
histologic thymus involution. Significant gene changes support the
hypothesis that multiple key intrathymic pathways are differentially
activated during stress-induced thymic involution. These included direct
activation of thymus tissue by LPS through TLR signaling, local expression
of inflammatory cytokines, inhibition of T cell signaling, and induction of
wound healing/tissue remodeling. Conclusions/Significance Taken together, these observations demonstrated that in addition to the
classic systemic response, a direct intrathymic response to endotoxin
challenge concurrently contributes to thymic involution during endotoxemia.
These findings are a substantial advancement over current understanding of
thymus response to stress and may lead to the development of novel
therapeutic approaches to ameliorate immune deficiency associated with
stress events.
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Affiliation(s)
- Matthew J. Billard
- Department of Biostatistics & Bioinformatics, Duke University Medical
Center, Durham, North Carolina, United States of America
| | - Amanda L. Gruver
- Department of Medicine, Department of Pathology, and the Duke University
Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina,
United States of America
| | - Gregory D. Sempowski
- Department of Medicine, Department of Pathology, and the Duke University
Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina,
United States of America
- * E-mail:
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5
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Chuang WY, Ströbel P, Belharazem D, Rieckmann P, Toyka KV, Nix W, Schalke B, Gold R, Kiefer R, Klinker E, Opitz A, Inoue M, Kuo TT, Müller-Hermelink HK, Marx A. The PTPN22gain-of-function+1858T(+) genotypes correlate with low IL-2 expression in thymomas and predispose to myasthenia gravis. Genes Immun 2009; 10:667-72. [PMID: 19693092 DOI: 10.1038/gene.2009.64] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Protein tyrosine phosphatase, non-receptor type 22 (PTPN22) inhibits T-cell activation and interleukin-2 (IL-2) production. The PTPN22(gain-of-function)+1858T(+) genotypes predispose to multiple autoimmune diseases, including early-onset (non-thymomatous) myasthenia gravis (MG). The disease association and the requirement of IL-2/IL-2 receptor signaling for intrathymic, negative T-cell selection have suggested that these genotypes may weaken T-cell receptor (TCR) signaling and impair the deletion of autoreactive T cells. Evidence for this hypothesis is missing. Thymoma-associated MG, which depends on intratumorous generation and export of mature autoreactive CD4(+) T cells, is a model of autoimmunity because of central tolerance failure. Here, we analyzed the PTPN22 +1858C/T single nucleotide polymorphism in 426 German Caucasian individuals, including 125 thymoma patients (79 with MG), and investigated intratumorous IL-2 expression levels. Unlike two previous studies on French and Swedish patients, we found strong association of PTPN22 +1858T(+) genotypes not only with early-onset MG (P=0.00034) but also with thymoma-associated MG (P=0.0028). IL-2 expression in thymomas with PTPN22 +1858T(+) genotypes (P=0.028) was lower, implying weaker TCR signaling. We conclude that the PTPN22(gain-of-function) variant biases towards MG in a subgroup of thymoma patients possibly by impeding central tolerance induction.
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Affiliation(s)
- W-Y Chuang
- Institute of Pathology, University of Würzburg, Würzburg, Germany
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6
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Enhanced selection of FoxP3+ T-regulatory cells protects CTLA-4-deficient mice from CNS autoimmune disease. Proc Natl Acad Sci U S A 2009; 106:3306-11. [PMID: 19218450 DOI: 10.1073/pnas.0803186106] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
It is generally acknowledged that cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4/CD152) plays a pivotal role in the regulation of T-cell activation and the establishment of self-tolerance in the periphery. CTLA-4-deficient (CTLA-4KO) mice develop a lymphoproliferative disorder and die within 4 weeks of birth, suggesting a role for CTLA-4 in T-cell homeostasis or the development and activity of T-regulatory (Treg) cells. To study the role of CTLA-4 in the control of experimental autoimmune encephalomyelitis (EAE), we have generated a CTLA-4KO mouse in which >90% of all CD4(+) T cells bear a Vbeta8.2 transgenic T-cell receptor that is specific for myelin basic protein peptide Ac1-9 (ASQKRPSQR). These mice do not develop spontaneous lymphoproliferative disease or EAE and are resistant to disease induction. This correlates with a higher frequency of functional FoxP3(+) Treg cells in the spleen and thymus of CTLA-4KO mice. The absence of CTLA-4-mediated suppression of CD28 signaling resulted in the early expression of FoxP3 on double-positive cells in the thymic cortex. We conclude that CTLA-4 is not essential for the peripheral function of FoxP3(+) Treg cells but plays a pivotal role in their thymic selection.
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7
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Barreto M, Ferreira RC, Lourenço L, Moraes-Fontes MF, Santos E, Alves M, Carvalho C, Martins B, Andreia R, Viana JF, Vasconcelos C, Mota-Vieira L, Ferreira C, Demengeot J, Vicente AM. Low frequency of CD4+CD25+ Treg in SLE patients: a heritable trait associated with CTLA4 and TGFbeta gene variants. BMC Immunol 2009; 10:5. [PMID: 19173720 PMCID: PMC2656467 DOI: 10.1186/1471-2172-10-5] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Accepted: 01/27/2009] [Indexed: 12/23/2022] Open
Abstract
Background CD4+CD25+ regulatory T cells play an essential role in maintaining immune homeostasis and preventing autoimmunity. Therefore, defects in Treg development, maintenance or function have been associated with several human autoimmune diseases including Systemic Lupus Erythematosus (SLE), a systemic autoimmune disease characterized by loss of tolerance to nuclear components and significantly more frequent in females. Results To investigate the involvement of Treg in SLE pathogenesis, we determined the frequency of CD4+CD25+CD45RO+ T cells, which encompass the majority of Treg activity, in the PBMC of 148 SLE patients (76 patients were part of 54 families), 166 relatives and 117 controls. SLE patients and their relatives were recruited in several Portuguese hospitals and through the Portuguese Lupus Association. Control individuals were blood donors recruited from several regional blood donor centers. Treg frequency was significantly lower in SLE patients than healthy controls (z = -6.161, P < 0.00001) and intermediate in the relatives' group. Remarkably, this T cell subset was also lower in females, most strikingly in the control population (z = 4.121, P < 0.001). We further ascertained that the decreased frequency of Treg in SLE patients resulted from the specific reduction of bona fide FOXP3+CD4+CD25+ Treg. Treg frequency was negatively correlated with SLE activity index (SLEDAI) and titers of serum anti-dsDNA antibodies. Both Treg frequency and disease activity were modulated by IVIg treatment in a documented SLE case. The segregation of Treg frequency within the SLE families was indicative of a genetic trait. Candidate gene analysis revealed that specific variants of CTLA4 and TGFβ were associated with the decreased frequency of Treg in PBMC, while FOXP3 gene variants were associated with affection status, but not with Treg frequency. Conclusion SLE patients have impaired Treg production or maintenance, a trait strongly associated with SLE disease activity and autoantibody titers, and possibly resulting from the inability to convert FOXP3+CD25- into FOXP3+CD25+ T cells. Treg frequency is highly heritable within SLE families, with specific variants of the CTLA4 and TGFβ genes contributing to this trait, while FOXP3 contributes to SLE through mechanisms not involving a modulation of Treg frequency. These findings establish that the genetic components in SLE pathogenesis include genes related to Treg generation or maintenance.
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Affiliation(s)
- Marta Barreto
- Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6 2780-156 Oeiras, Portugal.
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8
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Ahmed A, Mukherjee S, Nandi D. Intracellular concentrations of Ca(2+) modulate the strength of signal and alter the outcomes of cytotoxic T-lymphocyte antigen-4 (CD152)-CD80/CD86 interactions in CD4(+) T lymphocytes. Immunology 2008; 126:363-77. [PMID: 18710402 DOI: 10.1111/j.1365-2567.2008.02902.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The costimulatory receptors CD28 and cytotoxic T-lymphocyte antigen (CTLA)-4 and their ligands, CD80 and CD86, are expressed on T lymphocytes; however, their functional roles during T cell-T cell interactions are not well known. The consequences of blocking CTLA-4-CD80/CD86 interactions on purified mouse CD4(+) T cells were studied in the context of the strength of signal (SOS). CD4(+) T cells were activated with phorbol 12-myristate 13-acetate (PMA) and different concentrations of a Ca(2+) ionophore, Ionomycin (I), or a sarcoplasmic Ca(2+) ATPase inhibitor, Thapsigargin (TG). Increasing concentrations of I or TG increased the amount of interleukin (IL)-2, reflecting the conversion of a low to a high SOS. During activation with PMA and low amounts of I, intracellular concentrations of calcium ([Ca(2+)](i)) were greatly reduced upon CTLA-4-CD80/CD86 blockade. Further experiments demonstrated that CTLA-4-CD80/CD86 interactions reduced cell cycling upon activation with PMA and high amounts of I or TG (high SOS) but the opposite occurred with PMA and low amounts of I or TG (low SOS). These results were confirmed by surface T-cell receptor (TCR)-CD3 signalling using a low SOS, for example soluble anti-CD3, or a high SOS, for example plate-bound anti-CD3. Also, CTLA-4-CD80/CD86 interactions enhanced the generation of reactive oxygen species (ROS). Studies with catalase revealed that H(2)O(2) was required for IL-2 production and cell cycle progression during activation with a low SOS. However, the high amounts of ROS produced during activation with a high SOS reduced cell cycle progression. Taken together, these results indicate that [Ca(2+)](i) and ROS play important roles in the modulation of T-cell responses by CTLA-4-CD80/CD86 interactions.
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Affiliation(s)
- Asma Ahmed
- Department of Biochemistry, Indian Institute of Science, Bangalore, India
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9
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Verhagen J, Sabatos CA, Wraith DC. The role of CTLA-4 in immune regulation. Immunol Lett 2007; 115:73-4. [PMID: 18035425 PMCID: PMC2629540 DOI: 10.1016/j.imlet.2007.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 10/12/2007] [Indexed: 11/30/2022]
Affiliation(s)
- Johan Verhagen
- Corresponding author. Tel.: +44 117 3312008; fax: +44 117 9287896.
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10
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Teft WA, Madrenas J. Molecular determinants of inverse agonist activity of biologicals targeting CTLA-4. THE JOURNAL OF IMMUNOLOGY 2007; 179:3631-7. [PMID: 17785798 DOI: 10.4049/jimmunol.179.6.3631] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Ligation of CD28 or CTLA-4 with some biologicals can activate T cells due to an unexpected superagonist or inverse agonist activity, respectively. The risk of such an outcome limits the therapeutic development of these reagents. Thus, identifying the molecular determinants of superagonist/inverse agonist properties for biologicals targeting costimulatory/inhibitory receptors has not only fundamental value but also important therapeutic implications. In this study, we show that ligation of CTLA-4 with either soluble B7.1 Ig (but not B7.2 Ig) or with a recombinant bispecific in-tandem single chain Fv known as 24:26 induces TCR-independent, T cell activation. Such an inverse agonist activity requires CD28 expression and high CTLA-4 expression and is not seen when CTLA-4 is ligated by membrane-bound B7.1 or B7.2. At the molecular level, the inverse agonist activity of B7.1 Ig or 24:26 correlates with their ability to induce the formation of unique dimer-based, CTLA-4 oligomers on the T cell surface and involves CTLA-4 signaling through its cytoplasmic domain. Our results provide a potential mechanism to explain and to predict inverse agonist activity for CTLA-4 ligands.
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Affiliation(s)
- Wendy A Teft
- FOCIS Centre for Clinical Immunology and Immunotherapeutics, Robarts Research Institute, London, Ontario, Canada
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11
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Fevery S, Billiau AD, Sprangers B, Rutgeerts O, Lenaerts C, Goebels J, Landuyt W, Kasran A, Boon L, Sagaert X, De Wolf-Peeters C, Waer M, Vandenberghe P. CTLA-4 blockade in murine bone marrow chimeras induces a host-derived antileukemic effect without graft-versus-host disease. Leukemia 2007; 21:1451-9. [PMID: 17508005 DOI: 10.1038/sj.leu.2404720] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We studied the effect of CTLA-4 blockade on graft-versus-leukemia and graft-versus-host responses in a mouse model of minor histocompatibility-mismatched bone marrow transplantation. Early CTLA-4 blockade induced acute graft-versus-host disease. Delayed CTLA-4 blockade resulted in a lethal condition with lymphosplenomegaly, but with stable mixed T-cell chimerism, unchanged alloreactive T-cell frequencies and absent anti-host reactivity in vitro. In contrast, multiorgan lymphoproliferative disease with autoimmune hepatitis and circulating anti-DNA auto-antibodies were documented. Splenic lymphocytes exhibited ex vivo spontaneous proliferation and a marked proliferative response against host-type dendritic cells pulsed with syngeneic (host-type) tissue-peptides. Both phenomena were exclusively mediated by host and not donor T cells, supporting an autoimmune pathogenesis. Selectively host-derived T-cell immune reactivity was equally documented against leukemia-peptide-pulsed dendritic cells, and this was paralleled by a strong in vivo antileukemic effect in anti-CTLA-4-treated and subsequently leukemia-challenged chimeras. In conclusion, delayed CTLA-4 blockade induced a host-derived antileukemic effect, occurring in the context of an autoimmune syndrome and strictly separated from graft-versus-host disease. Both antileukemic and autoimmune responses depended on the allogeneic component, as neither effect was seen after syngeneic bone marrow transplantation. Our findings reveal the potential of using CTLA-4 blockade to establish antileukemic effects after allogeneic hematopoietic stem cell transplantation, provided autoimmunity can be controlled.
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Affiliation(s)
- S Fevery
- Laboratory of Experimental Transplantation, University of Leuven, Leuven, Belgium
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12
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Raué HP, Slifka MK. Pivotal advance: CTLA-4+ T cells exhibit normal antiviral functions during acute viral infection. J Leukoc Biol 2007; 81:1165-75. [PMID: 17215523 DOI: 10.1189/jlb.0806535] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Previous studies have shown that T cells, which are genetically deficient in CTLA-4/CD152 expression, will proliferate uncontrollably, resulting in lethal autoimmune disease. This and other evidence indicate that CTLA-4 plays a critical role in the negative regulation of effector T cell function. In contrast to expectations, BrdU incorporation experiments demonstrated that CTLA-4 expression was associated with normal or even enhanced in vivo proliferation of virus-specific CD4+ and CD8+ T cells following acute lymphocytic choriomeningitis virus or vaccinia virus infection. When compared with CTLA-4- T cells directly ex vivo, CTLA-4+ T cells also exhibited normal antiviral effector functions following stimulation with peptide-coated cells, virus-infected cells, plate-bound anti-CD3/anti-CTLA-4, or the cytokines IL-12 and IL-18. Together, this indicates that CTLA-4 does not directly inhibit antiviral T cell expansion or T cell effector functions, at least not under the normal physiological conditions associated with either of these two acute viral infections.
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Affiliation(s)
- Hans-Peter Raué
- Vaccine and Gene Therapy Institute, Oregon Health and Science University, 505 N.W. 185th Avenue, Beaverton, OR 97006, USA
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13
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Zhang J, Gong Y, Shao X, Zhang R, Xu W, Chu Y, Wang Y, Xiong S. Asynchronism of Thymocyte Development In Vivo and In Vitro. DNA Cell Biol 2007; 26:19-27. [PMID: 17263593 DOI: 10.1089/dna.2006.0525] [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] [Indexed: 02/01/2023] Open
Abstract
Although fetal thymus organ culture (FTOC) has become widely used to investigate T-cell development, the differences between thymocyte development in vivo and in vitro (in FTOC) remain largely unknown. In this study, the viability and numbers of thymocytes recovered from embryonic thymus lobes in different gestation days (gd) mice or from 15 day embryonic thymus lobes cultured for different days in FTOC system were evaluated. The expression of CD3, CD4, CD8, CD95 ligand (CD95L), and CD69 on thymocytes were analyzed by FACS. The results showed that thymocytes, either in vivo or in vitro, could differentiate from double negative (DN) cells to double positive (DP) cells and to single positive (SP) cells. But the number of total thymocytes and the percentage of DP cells in vitro were less than that in vivo, and the expression of CD95L and CD69 on thymocytes in vitro was higher than that in vivo. Our results suggested that although thymocyte development in vitro could recapitulate thymic development in vivo, the proliferation of thymocytes in vitro was less intensive than that in vivo; the differentiation of thymocytes in vitro was delayed compared with that in vivo; and the apoptosis and activation of thymocytes in vitro were higher than that in vivo. In conclusion, FTOC is a useful system for the study of T cell differentiation, but it is necessary to interpret the results from in vitro studies carefully since the thymocyte development in vitro is asynchronous from that in vivo.
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Affiliation(s)
- Jinping Zhang
- Institute for Immunobiology, Department of Immunology of Shanghai Medical College of Fudan University, and Immunology Division, E-Institutes of Shanghai Universities, Shanghai, People's Republic of China
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14
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Abstract
Within the paradigm of the two-signal model of lymphocyte activation, the interest in costimulation has witnessed a remarkable emergence in the past few years with the discovery of a large array of molecules that can serve this role, including some with an inhibitory function. Interest has been further enhanced by the realization of these molecules' potential as targets to modulate clinical immune responses. Although the therapeutic translation of mechanistic knowledge in costimulatory molecules has been relatively straightforward, the capacity to target their inhibitory counterparts has remained limited. This limited capacity is particularly apparent in the case of the cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), a major negative regulator of T cell responses. Because there have been several previous comprehensive reviews on the function of this molecule, we focus here on the physiological implications of its structural features. Such an exercise may ultimately help us to design immunotherapeutic agents that target CTLA-4.
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MESH Headings
- Amino Acid Sequence
- Animals
- Antigens, CD
- Antigens, Differentiation/chemistry
- Antigens, Differentiation/genetics
- Antigens, Differentiation/metabolism
- Biological Transport, Active
- CTLA-4 Antigen
- Dimerization
- Evolution, Molecular
- Humans
- Ligands
- Lymphocyte Activation
- Models, Immunological
- Molecular Biology
- Molecular Sequence Data
- Polymorphism, Genetic
- Protein Structure, Quaternary
- Sequence Homology, Amino Acid
- Signal Transduction
- T-Lymphocytes/immunology
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Affiliation(s)
- Wendy A Teft
- The FOCIS Center for Clinical Immunology and Immunotherapeutics, Robarts Research Institute, and Department of Microbiology and Immunology, University of Western Ontario, London, Ontario, Canada, N6A 5K8
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15
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Yoo JK, Kwon H, Khil LY, Zhang L, Jun HS, Yoon JW. IL-18 Induces Monocyte Chemotactic Protein-1 Production in Macrophages through the Phosphatidylinositol 3-Kinase/Akt and MEK/ERK1/2 Pathways. THE JOURNAL OF IMMUNOLOGY 2005; 175:8280-6. [PMID: 16339568 DOI: 10.4049/jimmunol.175.12.8280] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Macrophages are activated during an inflammatory response and produce multiple inflammatory cytokines. IL-18 is one of the most important innate cytokines produced from macrophages in the early stages of the inflammatory immune response. Monocyte chemoattractant protein (MCP-1) is expressed in many inflammatory diseases such as multiple sclerosis and rheumatoid arthritis, and its expression is correlated with the severity of the disease. Both IL-18 and MCP-1 have been shown to be involved in inflammatory immune responses. However, it has been unclear whether IL-18 is involved in the induction of MCP-1. This investigation was initiated to determine whether IL-18 can induce MCP-1 production, and if so, by which signal transduction pathways. We found that IL-18 induced the production of MCP-1 in macrophages, which was IL-12-independent and was not mediated by autocrine cytokines such as IFN-gamma or TNF-alpha. We then examined signal transduction pathways involved in IL-18-induced MCP-1 production. We found that IL-18 did not activate the IkappaB kinase/NF-kappaB pathway, evidenced by no degradation of IkappaBalpha and no translocation of NF-kappaB p65 to the nucleus in IL-18-stimulated macrophages. Instead, IL-18 activated the PI3K/Akt and MEK/ERK1/2 pathways. Inhibition of either of these pathways attenuated MCP-1 production in macrophages, and inhibition of both signaling pathways resulted in the complete inhibition of MCP-1 production. On the basis of these observations, we conclude that IL-18 induces MCP-1 production through the PI3K/Akt and MEK/ERK1/2 pathways in macrophages.
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Affiliation(s)
- Jae Kwang Yoo
- Department of Microbiology and Infectious Diseases, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada
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