Rap1-GTP Promotes the Generation of Regulatory T Cells in Vivo.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 110-110
Author(s):  
Lequn Li ◽  
Rebecca Greenwald ◽  
Esther M. Lafuente ◽  
Dimitrios Tzachanis ◽  
Alla Berezovskaya ◽  
...  
Keyword(s):  
T Cells ◽  
Lymph Node ◽  
T Cell ◽  
Regulatory T Cells ◽  
Immune Responses ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cd4 Cells

Abstract Elucidating the mechanisms that regulate T cell activation and tolerance in vivo will provide insights into the maintenance of physiologic homeostasis and will facilitate development novel strategies for induction of transplantation tolerance. Transient activation of the small GTPase Rap1 is one of the physiologic consequences of TCR ligation and is mandatory for β1 and β2 integrin-mediated adhesion. In contrast, sustained increase of active Rap1 inhibits T cell activation and IL-2 transcription in vitro. In order to understand the role of Rap1 in the immune responses of the intact host we generated transgenic (Tg) mice, which express the active Rap1 mutant Rap1E63 in T cells. Rap1E63-Tg mice had no defects in thymocyte development or maturation. Rap1E63-Tg thymocytes were capable of activating Ras and Erk1/2 and, compared to wild type (WT) thymocytes, displayed enhanced LFA-1:ICAM-1-mediated adhesion and increased proliferation in response to anti-CD3. Surprisingly, although lymph node and splenic CD4+ cells from the Rap1E63-Tg mice also displayed increased LFA-1:ICAM-1-mediated adhesion, they had significantly impaired activation of Erk1/2 and dramatically reduced proliferation and IL-2 production in response to anti-CD3 and WT antigen presenting cells (APC). The defective responses of CD4+ T cells suggest that Rap1E63-Tg mice may have impaired helper function in vivo. To address this issue we immunized Rap1E63-Tg and WT mice with TNP-OVA, a T-cell dependent antigen. Total IgG, IgG1 and IgG2a were dramatically reduced, indicating that Rap1E63-Tg mice had a defect in immunoglobulin class switching, consistent with defective helper T cell-dependent B cell activation. Because these results suggest that Rap1E63-Tg CD4+ cells may have an anergic phenotype, we tested rechallenge responses. We immunized Rap1E63-Tg and WT mice with TNP-OVA in vivo and subsequently we rechallenged T cells in vitro with WT APC pulsed with OVA. Compared with WT, Rap1E63-Tg T cells had dramatically reduced proliferation, IFN- γ and IL-2 production on rechallenge, findings consistent with T cell anergy. Using suppression subtraction hybridization we determined that Rap1E63 induced mRNA expression of CD103, a marker that defines a potent subset of regulatory T cells (Treg). Strikingly, Rap1E63-Tg mice had a 5-fold increase of CD103+CD25+CD4+ Treg compared to WT mice. Rap1E63-Tg CD103+CD25+CD4+ Treg expressed the highest level of Foxp3 among all T cell subsets and had the most potent inhibitory effect on proliferation and IL-2 production when added into cultures of WT CD4+CD25− cells. Importantly, removal of the CD103+ cells significantly restored Erk1/2 activation, proliferation and IL-2 production of Rap1E63-Tg CD4+ T cells. Generation of CD103+ Treg occurs after thymic development and requires encounter of peripheral autoantigen. Consistent with this, differences in CD103+ Treg were detected only between lymph node and splenic cells and not between thymocytes from Rap1E63-Tg and WT mice. Since generation of CD103+ Treg depends on the strength of TCR signal, these results suggest that by enhancing adhesion, active Rap1 regulates the generation of Treg. Moreover, these results provide evidence that active Rap1 is a potent negative regulator of immune responses in vivo and have significant implications for the development of immune-based therapies geared towards tolerance induction.

scholarly journals Antigen-pulsed CD8α+ Dendritic Cells Generate an Immune Response after Subcutaneous Injection without Homing to the Draining Lymph Node

1999 ◽  
Vol 189 (3) ◽  
pp. 593-598 ◽  
Author(s):  
Adrian L. Smith ◽  
Barbara Fazekas de St. Groth
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Lymph Node ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Myeloid Dendritic Cells ◽  
Draining Lymph Node

Two subsets of murine splenic dendritic cells, derived from distinct precursors, can be distinguished by surface expression of CD8α homodimers. The functions of the two subsets remain controversial, although it has been suggested that the lymphoid-derived (CD8α+) subset induces tolerance, whereas the myeloid-derived (CD8α−) subset has been shown to prime naive T cells and to generate memory responses. To study their capacity to prime or tolerize naive CD4+ T cells in vivo, purified CD8α+ or CD8α− dendritic cells were injected subcutaneously into normal mice. In contrast to CD8α− dendritic cells, the CD8α+ fraction failed to traffic to the draining lymph node and did not generate responses to intravenous peptide. However, after in vitro pulsing with peptide, strong in vivo T cell responses to purified CD8α+ dendritic cells could be detected. Such responses may have been initiated via transfer of peptide–major histocompatibility complex complexes to migratory host CD8α− dendritic cells after injection. These data suggest that correlation of T helper cell type 1 (Th1) and Th2 priming with injection of CD8α+ and CD8α− dendritic cells, respectively, may not result from direct T cell activation by lymphoid versus myeloid dendritic cells, but rather from indirect modification of the response to immunogenic CD8α− dendritic cells by CD8α+ dendritic cells.

Lenalidomide Decreases PD-1 Expression, Depletes Regulatory T-Cells and Improves Cellular Response to a Multiple Myeloma/Dendritic Cell Fusion Vaccine In Vitro

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 492-492 ◽  
Author(s):  
Katarina Luptakova ◽  
Brett Glotzbecker ◽  
Heidi Mills ◽  
Dina Stroopinsky ◽  
Baldev Vasir ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
T Cell Activation ◽  
Cell Activation ◽  
Fold Increase ◽  
Cellular Immunotherapy ◽  
Cd4 Cells

Abstract Abstract 492 Introduction: We have developed a cancer vaccine for multiple myeloma in which patient derived tumor cells are fused with dendritic cells (DCs) such that a broad array of tumor antigens are presented in the context of DC mediated costimulation. In clinical studies, we have demonstrated that vaccination results in the induction of anti-tumor immunity and disease response in a subset of patients. A fundamental challenge limiting the efficacy of cellular immunotherapy is the immunosuppressive milieu that characterizes patients with myeloma. We have previously reported that the PD-1/PDL-1 pathway plays an important role in suppressing T cell immunity in patients with myeloma, PD-1 expression is upregulated on T cells isolated from patients with multiple myeloma, and PD-1 blockade is associated with enhancement of T-cell response to the vaccine. Lenalidomide is a potent anti-myeloma agent whose activity may be linked, in part, to its immunomodulatory properties. We hypothesized that lenalidomide would augment the capacity to elicit anti-myeloma immunity. In our current study, we examined the effect of lenalidomide on T-cell activation and polarization, PD-1 signaling, and vaccine-induced responses in vitro. Methods and results: Peripheral blood mononuclear cells were cultured in media containing IL-2 with and without 1μM lenalidomide. The expression of cell surface molecules and intracellular cytokines was assessed using flow cytometry. Exposure of unstimulated T cells to lenalidomide resulted in a decrease in the percentage of CD4+ T cells expressing PD-1 (from 8.0% to 5.6%, p=0.04) and a 2 fold increase in T-cell proliferation as measured by incorporation of tritiated thymidine. We then examined the effect of lenalidomide on T cell activation by ligation of the costimulatory complex using antibodies directed against CD3 and anti CD28. Most notably, the upregulation of PD-1 by CD3/CD28 ligation was markedly decreased in the presence of lenalidomide as measured in CD4+ cells (from 26% to 15%, p<0.0001) and in CD8+ cells (from 16% to 10% p<0.01). Ligation of CD3/CD28 in the presence of lenalidomide resulted in greater degree of Th1 polarization as manifested by a 2 fold increase in the percentage of CD8+ T cells expressing IFNγ (p=0.02) and a decrease in the percentage of regulatory T-cells (CD4+CD25+FoxP3+) from 6.88% to 3.13% (p=0.02). In addition, the percentage of NK cells (CD3-CD56+) expressing IFNγ following CD3/CD28 ligation was 5-fold greater (p=0.03) in the presence of lenalidomide. Lastly, we studied the effect of lenalidomide on T-cells stimulated in vitro by the DC/myeloma fusion vaccine. DC/myeloma fusions were generated as previously described. Fusion mediated stimulation of autologous T cells in the presence of lenalidomide resulted in an increase in the percentage CD4+ and CD8+ T cells expressing IFNγ, (5.35% to 8.79%, p=0.06; and 6.37% to 9.85%, p=0.03, respectively). The proportion of regulatory T-cells decreased from 9.57% to 4.43% in the presence of lenalidomide (p<0.01). As with non-specific stimulation, PD-1 expression on CD4+ cells in the presence of lenalidomide decreased from 24% to 19%. In concert with these findings, exposure to lenalidomide resulted in increased cytotoxic T lymphocyte mediated lysis of autologous tumor targets (from 25% to 36%). Conclusions: In vitro exposure to lenalidomide results in enhanced T-cell activation in response to direct ligation of the co-stimulatory complex and stimulation by the DC/myeloma fusion vaccine. Exposure to lenalidomide suppresses T cell expression of PD-1 and expansion of regulatory T cells, 2 critical pathways responsible for tumor mediated immune suppression. To our knowledge, this is the first demonstration of an interaction between lenalidomide and the PD-1/PDL-1 pathway. These findings support the development of cellular immunotherapy in conjunction with lenalidomide, including its use with the DC/myeloma fusion vaccine. Disclosures: No relevant conflicts of interest to declare.

scholarly journals MARCH1-mediated MHCII ubiquitination promotes dendritic cell selection of natural regulatory T cells

2013 ◽  
Vol 210 (6) ◽  
pp. 1069-1077 ◽  
Author(s):  
Jaehak Oh ◽  
Nan Wu ◽  
Günther Baravalle ◽  
Benjamin Cohn ◽  
Jessica Ma ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
T Cell Activation ◽  
Cell Activation ◽  
Substantial Reduction ◽  
Surface Expression ◽  
Selection Of

Membrane-associated RING-CH1 (MARCH1) is an E3 ubiquitin ligase that mediates ubiquitination of MHCII in dendritic cells (DCs). MARCH1-mediated MHCII ubiquitination in DCs is known to regulate MHCII surface expression, thereby controlling DC-mediated T cell activation in vitro. However, its role at steady state or in vivo is not clearly understood. Here, we show that MARCH1 deficiency resulted in a substantial reduction in the number of thymus-derived regulatory T cells (T reg cells) in mice. A specific ablation of MHCII ubiquitination also significantly reduced the number of thymic T reg cells. Indeed, DCs deficient in MARCH1 or MHCII ubiquitination both failed to generate antigen-specific T reg cells in vivo and in vitro, although both exhibited an increased capacity for antigen presentation in parallel with the increased surface MHCII. Thus, MARCH1-mediated MHCII ubiquitination in DCs is required for proper production of naturally occurring T reg cells, suggesting a role in balancing immunogenic and regulatory T cell development.

scholarly journals TRPM2 Is Not Required for T-Cell Activation and Differentiation

2022 ◽  
Vol 12 ◽  
Author(s):  
Niels C. Lory ◽  
Mikolaj Nawrocki ◽  
Martina Corazza ◽  
Joanna Schmid ◽  
Valéa Schumacher ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Transient Receptor Potential ◽  
Cell Function ◽  
Intestinal Inflammation ◽  
Activation Markers

Antigen recognition by the T-cell receptor induces a cytosolic Ca2+ signal that is crucial for T-cell function. The Ca2+ channel TRPM2 (transient receptor potential cation channel subfamily M member 2) has been shown to facilitate influx of extracellular Ca2+ through the plasma membrane of T cells. Therefore, it was suggested that TRPM2 is involved in T-cell activation and differentiation. However, these results are largely derived from in vitro studies using T-cell lines and non-physiologic means of TRPM2 activation. Thus, the relevance of TRPM2-mediated Ca2+ signaling in T cells remains unclear. Here, we use TRPM2-deficient mice to investigate the function of TRPM2 in T-cell activation and differentiation. In response to TCR stimulation in vitro, Trpm2-/- and WT CD4+ and CD8+ T cells similarly upregulated the early activation markers NUR77, IRF4, and CD69. We also observed regular proliferation of Trpm2-/- CD8+ T cells and unimpaired differentiation of CD4+ T cells into Th1, Th17, and Treg cells under specific polarizing conditions. In vivo, Trpm2-/- and WT CD8+ T cells showed equal specific responses to Listeria monocytogenes after infection of WT and Trpm2-/- mice and after transfer of WT and Trpm2-/- CD8+ T cells into infected recipients. CD4+ T-cell responses were investigated in the model of anti-CD3 mAb-induced intestinal inflammation, which allows analysis of Th1, Th17, Treg, and Tr1-cell differentiation. Here again, we detected similar responses of WT and Trpm2-/- CD4+ T cells. In conclusion, our results argue against a major function of TRPM2 in T-cell activation and differentiation.

scholarly journals Modulating p56Lck in T-Cells by a Chimeric Peptide Comprising Two Functionally Different Motifs of Tip fromHerpesvirus saimiri

2015 ◽  
Vol 2015 ◽  
pp. 1-12
Author(s):  
Jean-Paul Vernot ◽  
Ana María Perdomo-Arciniegas ◽  
Luis Alberto Pérez-Quintero ◽  
Diego Fernando Martínez
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lipid Rafts ◽  
T Cell Activation ◽  
Cell Activation ◽  
Jurkat Cells ◽  
Chimeric Peptide ◽  
Vector Targeting

The Lck interacting protein Tip ofHerpesvirus saimiriis responsible for T-cell transformation bothin vitroandin vivo. Here we designed the chimeric peptide hTip-CSKH, comprising the Lck specific interacting motif CSKH of Tip and its hydrophobic transmembrane sequence (hTip), the latter as a vector targeting lipid rafts. We found that hTip-CSKH can induce a fivefold increase in proliferation of human andAotussp. T-cells. Costimulation with PMA did not enhance this proliferation rate, suggesting that hTip-CSKH is sufficient and independent of further PKC stimulation. We also found that human Lck phosphorylation was increased earlier after stimulation when T-cells were incubated previously with hTip-CSKH, supporting a strong signalling and proliferative effect of the chimeric peptide. Additionally, Lck downstream signalling was evident with hTip-CSKH but not with control peptides. Importantly, hTip-CSKH could be identified in heavy lipid rafts membrane fractions, a compartment where important T-cell signalling molecules (LAT, Ras, and Lck) are present during T-cell activation. Interestingly, hTip-CSKH was inhibitory to Jurkat cells, in total agreement with the different signalling pathways and activation requirements of this leukemic cell line. These results provide the basis for the development of new compounds capable of modulating therapeutic targets present in lipid rafts.

T cell-T cell activation in multiple sclerosis

1997 ◽  
Vol 3 (4) ◽  
pp. 238-242 ◽  
Author(s):  
JW Lindsey ◽  
RH Kerman ◽  
JS Wolinsky
Keyword(s):  
Multiple Sclerosis ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Viral Infections ◽  
Activated T Cells ◽  
In Vitro Proliferation

Activated T cells are able to stimulate proliferation in resting T cells through an antigen non-specific mechanism. The in vivo usefulness of this T cell-T cell activation is unclear, but it may serve to amplify immune responses. T cell-T cell activation could be involved in the well-documented occurrence of multiple sclerosis (MS) exacerbations following viral infections. Excessive activation via this pathway could also be a factor in the etiology of MS. We tested the hypothesis that excessive T cell-T cell activation occurs in MS patients using in vitro proliferation assays comparing T cells from MS patients to T cells from controls. When tested as responder cells, T cells from MS patients proliferated slightly less after stimulation with previously activated cells than T cells from controls. When tested as stimulator cells, activated cells from MS patients stimulated slightly more non-specific proliferation than activated cells from controls. Neither of these differences were statistically significant We conclude that T cell proliferation in response to activated T cells is similar in MS and controls.

scholarly journals Murine regulatory T cells differ from conventional T cells in resisting the CTLA-4 reversal of TCR stop-signal

Blood ◽  
2012 ◽  
Vol 120 (23) ◽  
pp. 4560-4570 ◽  
Author(s):  
Yuning Lu ◽  
Helga Schneider ◽  
Christopher E. Rudd
Keyword(s):  
T Cells ◽  
T Cell ◽  
Regulatory T Cells ◽  
Immune Responses ◽  
T Cell Activation ◽  
Cell Activation ◽  
Mechanistic Explanation ◽  
Stop Signal ◽  
Detectable Effect ◽  
First Time

Abstract CTLA-4 inhibits T-cell activation and protects against the development of autoimmunity. We and others previously showed that the coreceptor can induce T-cell motility and shorten dwell times with dendritic cells (DCs). However, it has been unclear whether this property of CTLA-4 affects both conventional T cells (Tconvs) and regulatory T cells (Tregs). Here, we report that CTLA-4 had significantly more potent effects on the motility and contact times of Tconvs than Tregs. This was shown firstly by anti–CTLA-4 reversal of the anti-CD3 stop-signal on FoxP3-negative cells at concentrations that had no effect on FoxP3-positive Tregs. Secondly, the presence of CTLA-4 reduced the contact times of DO11.10 x CD4+CD25− Tconvs, but not DO11.10 x CD4+CD25+ Tregs, with OVA peptide presenting DCs in lymph nodes. Thirdly, blocking of CTLA-4 with anti–CTLA-4 Fab increased the contact times of Tconvs, but not Tregs with DCs. By contrast, the presence of CD28 in a comparison of Cd28−/− and Cd28+/+ DO11.10 T cells had no detectable effect on the contact times of either Tconvs or Tregs with DCs. Our findings identify for the first time a mechanistic explanation to account for CTLA-4–negative regulation of Tconv cells but not Tregs in immune responses.

scholarly journals Signaling function of PRC2 is essential for TCR-driven T cell responses

2018 ◽  
Vol 215 (4) ◽  
pp. 1101-1113 ◽  
Author(s):  
Marc-Werner Dobenecker ◽  
Joon Seok Park ◽  
Jonas Marcello ◽  
Michael T. McCabe ◽  
Richard Gregory ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Therapeutic Potential ◽  
Cell Types ◽  
Polycomb Repressive Complex 2 ◽  
Histone Lysine Methyltransferases

Differentiation and activation of T cells require the activity of numerous histone lysine methyltransferases (HMT) that control the transcriptional T cell output. One of the most potent regulators of T cell differentiation is the HMT Ezh2. Ezh2 is a key enzymatic component of polycomb repressive complex 2 (PRC2), which silences gene expression by histone H3 di/tri-methylation at lysine 27. Surprisingly, in many cell types, including T cells, Ezh2 is localized in both the nucleus and the cytosol. Here we show the presence of a nuclear-like PRC2 complex in T cell cytosol and demonstrate a role of cytosolic PRC2 in T cell antigen receptor (TCR)–mediated signaling. We show that short-term suppression of PRC2 precludes TCR-driven T cell activation in vitro. We also demonstrate that pharmacological inhibition of PRC2 in vivo greatly attenuates the severe T cell–driven autoimmunity caused by regulatory T cell depletion. Our data reveal cytoplasmic PRC2 is one of the most potent regulators of T cell activation and point toward the therapeutic potential of PRC2 inhibitors for the treatment of T cell–driven autoimmune diseases.

scholarly journals Cd2 Sets Quantitative Thresholds in T Cell Activation

1999 ◽  
Vol 190 (10) ◽  
pp. 1383-1392 ◽  
Author(s):  
Martin F. Bachmann ◽  
Marijke Barner ◽  
Manfred Kopf
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Dose Response ◽  
Response Curve ◽  
Cell Activation ◽  
Dose Response Curve ◽  
Lymphocyte Function

It has been proposed that CD2, which is highly expressed on T cells, serves to enhance T cell–antigen presenting cell (APC) adhesion and costimulate T cell activation. Here we analyzed the role of CD2 using CD2-deficient mice crossed with transgenic mice expressing a T cell receptor specific for lymphocytic choriomeningitis virus (LCMV)-derived peptide p33. We found that absence of CD2 on T cells shifted the p33-specific dose–response curve in vitro by a factor of 3–10. In comparison, stimulation of T cells in the absence of lymphocyte function–associated antigen (LFA)-1–intercellular adhesion molecule (ICAM)-1 interaction shifted the dose–response curve by a factor of 10, whereas absence of both CD2–CD48 and LFA-1–ICAM-1 interactions shifted the response by a factor of ∼100. This indicates that CD2 and LFA-1 facilitate T cell activation additively. T cell activation at low antigen density was blocked at its very first steps, as T cell APC conjugate formation, TCR triggering, and Ca2+ fluxes were affected by the absence of CD2. In vivo, LCMV-specific, CD2-deficient T cells proliferated normally upon infection with live virus but responded in a reduced fashion upon cross-priming. Thus, CD2 sets quantitative thresholds and fine-tunes T cell activation both in vitro and in vivo.

scholarly journals In Vivo Detection of Dendritic Cell Antigen Presentation to CD4+ T Cells

1997 ◽  
Vol 185 (12) ◽  
pp. 2133-2141 ◽  
Author(s):  
Elizabeth Ingulli ◽  
Anna Mondino ◽  
Alexander Khoruts ◽  
Marc K. Jenkins
Keyword(s):  
T Cells ◽  
T Cell ◽  
Lymph Nodes ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Delayed Type Hypersensitivity ◽  
Physical Interaction

Although lymphoid dendritic cells (DC) are thought to play an essential role in T cell activation, the initial physical interaction between antigen-bearing DC and antigen-specific T cells has never been directly observed in vivo under conditions where the specificity of the responding T cells for the relevant antigen could be unambiguously assessed. We used confocal microscopy to track the in vivo location of fluorescent dye-labeled DC and naive TCR transgenic CD4+ T cells specific for an OVA peptide–I-Ad complex after adoptive transfer into syngeneic recipients. DC that were not exposed to the OVA peptide, homed to the paracortical regions of the lymph nodes but did not interact with the OVA peptide-specific T cells. In contrast, the OVA peptide-specific T cells formed large clusters around paracortical DC that were pulsed in vitro with the OVA peptide before injection. Interactions were also observed between paracortical DC of the recipient and OVA peptide-specific T cells after administration of intact OVA. Injection of OVA peptide-pulsed DC caused the specific T cells to produce IL-2 in vivo, proliferate, and differentiate into effector cells capable of causing a delayed-type hypersensitivity reaction. Surprisingly, by 48 h after injection, OVA peptide-pulsed, but not unpulsed DC disappeared from the lymph nodes of mice that contained the transferred TCR transgenic population. These results demonstrate that antigen-bearing DC directly interact with naive antigen-specific T cells within the T cell–rich regions of lymph nodes. This interaction results in T cell activation and disappearance of the DC.

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