scholarly journals Expression of Tim-3 drives naïve Treg to an effector-like state with enhanced suppressive activity

2020 ◽  
Author(s):  
Hridesh Banerjee ◽  
Hector Nieves-Rosado ◽  
Aditi Kulkarni ◽  
Benjamin Murter ◽  
Uma R. Chandran ◽  
...  
Keyword(s):  
T Cell ◽  
Tumor Immunity ◽  
T Cell Activation ◽  
Cell Activation ◽  
Suppressive Activity ◽  
Tcr Signaling ◽  
Self Tolerance ◽  
A Cell ◽  
Cell Type Specific

AbstractRegulatory T cells (Treg) are critical mediators of self-tolerance but can also limit effective anti-tumor immunity. We and others previously reported that 40-60% percent of Treg-infiltrating head and neck cancer (HNC) and other tumors highly express Tim-3, compared with about 5% in lymphoid organs. Tumor-infiltrating Tim-3+ Treg also have enhanced suppressive function and display a more effector-like phenotype. Using a novel mouse model with cell type-specific Tim-3 expression, we show here that expression of Tim-3 by Treg is sufficient to drive Treg to a more effector-like phenotype, resulting in enhanced suppressive activity and increased tumor growth. These findings may help to reconcile previous reports that some Tim-3 antibodies enhance T cell responses in vivo, while expression of Tim-3 has a cell-intrinsic ability to enhance TCR signaling and T cell activation. Thus, we propose that Tim-3 regulates anti-tumor immunity at least in part through enhancement of Treg function. To our knowledge, this is the first example in which expression of a single co-stimulatory molecule is sufficient to drive differentiation of Treg in this manner.

scholarly journals Reciprocal regulation of STING and TCR signaling by mTORC1 for T-cell activation and function

2019 ◽  
Vol 2 (1) ◽  
pp. e201800282 ◽  
Author(s):  
Takayuki Imanishi ◽  
Midori Unno ◽  
Wakana Kobayashi ◽  
Natsumi Yoneda ◽  
Satoshi Matsuda ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Physiological Role ◽  
Type I ◽  
Tcr Signaling ◽  
Reciprocal Regulation ◽  
Cell Functions

Stimulator of interferon genes (STING) plays a key role in detecting cytosolic DNA and induces type I interferon (IFN-I) responses for host defense against pathogens. Although T cells highly express STING, its physiological role remains unknown. Here, we show that costimulation of T cells with the STING ligand cGAMP and TCR leads to IFN-I production and strongly inhibits T-cell growth. TCR-mediated mTORC1 activation and sustained activation of IRF3 are required for cGAMP-induced IFN-I production, and the mTORC1 activity is partially counteracted by cGAMP, thereby blocking proliferation. This mTORC1 inhibition in response to costimulation depends on IRF3 and IRF7. Effector T cells produce much higher IFN-I levels than innate cells in response to cGAMP. Finally, we demonstrated that STING stimulation in T cells is effective in inducing antitumor responses in vivo. Our studies demonstrate that the outputs of STING and TCR signaling pathways are mutually regulated through mTORC1 to modulate T-cell functions.

Naturally arising CD4+CD25+ regulatory T cells suppress the expansion of colitogenic CD4+CD44highCD62L− effector memory T cells

2006 ◽  
Vol 290 (5) ◽  
pp. G1051-G1058 ◽  
Author(s):  
T. Kanai ◽  
K. Tanimoto ◽  
Y. Nemoto ◽  
R. Fujii ◽  
S. Makita ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Effector Memory ◽  
Late Time ◽  
Suppressive Activity ◽  
Time Point

Naturally arising CD4+CD25+ regulatory T (TR) cells have been shown to prevent and cure murine T cell-mediated colitis. However, their exact mechanism of controlling colitogenic memory CD4+ T cells in in vivo systems excluding the initial process of naive T cell activation and differentiation has not been examined to date. Using the colitogenic effector memory (TEM) CD4+ cell-mediated colitis model induced by adoptive transfer of colitogenic CD4+CD44highCD62L− lamina propria (LP) T cells obtained from colitic CD4+CD45RBhigh T cell-transferred mice, we have shown in the present study that CD4+CD25+ TR cells are able not only to suppress the development of colitis, Th1 cytokine production, and the expansion of colitogenic LP CD4+ TEM cells but also to expand these cells by themselves extensively in vivo. An in vitro coculture assay revealed that CD4+CD25+ TR cells proliferated in the presence of IL-2-producing colitogenic LP CD4+ TEM cells at the early time point (48 h after culture), followed by the acquisition of suppressive activity at the late time point (96 h after culture). Collectively, these data suggest the distinct timing of the IL-2-dependent expansion of CD4+CD25+ TR cells and the their suppressive activity on colitogenic LP CD4+ TEM cells.

scholarly journals Topological Requirements and Signaling Properties of T Cell–activating, Anti-CD28 Antibody Superagonists

2003 ◽  
Vol 197 (8) ◽  
pp. 955-966 ◽  
Author(s):  
Fred Lühder ◽  
Yun Huang ◽  
Kevin M. Dennehy ◽  
Christine Guntermann ◽  
Ingrid Müller ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Nuclear Factor Κb ◽  
Tcr Signaling ◽  
D Loop ◽  
Full Activation

Full activation of naive T cells requires both engagement of the T cell antigen receptor (TCR; signal 1) and costimulatory signaling by CD28 (signal 2). We previously identified two types of rat CD28-specific monoclonal antibodies (mAbs): “conventional,” TCR signaling–dependent costimulatory mAbs and “superagonistic” mAbs capable of inducing the full activation of primary resting T cells in the absence of TCR ligation both in vitro and in vivo. Using chimeric rat/mouse CD28 molecules, we show that the superagonists bind exclusively to the laterally exposed C′′D loop of the immunoglobulin-like domain of CD28 whereas conventional, costimulatory mAbs recognize an epitope close to the binding site for the natural CD80/CD86 ligands. Unexpectedly, the C′′D loop reactivity of a panel of new antibodies raised against human CD28 could be predicted solely on the basis of their superagonistic properties. Moreover, mouse CD28 molecules engineered to express the rat or human C′′D loop sequences activated T cell hybridomas without TCR ligation when cross-linked by superagonistic mAbs. Finally, biochemical analysis revealed that superagonistic CD28 signaling activates the nuclear factor κB pathway without inducing phosphorylation of either TCRζ or ZAP70. Our findings indicate that the topologically constrained interactions of anti-CD28 superagonists bypass the requirement for signal 1 in T cell activation. Antibodies with this property may prove useful for the development of T cell stimulatory drugs.

scholarly journals Regulation of T cell-dendritic cell interactions by IL-7 governs T-cell activation and homeostasis

Blood ◽  
2009 ◽  
Vol 113 (23) ◽  
pp. 5793-5800 ◽  
Author(s):  
Manoj Saini ◽  
Claire Pearson ◽  
Benedict Seddon
Keyword(s):  
T Cells ◽  
T Cell ◽  
Dendritic Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
T Cell Responses ◽  
Tcr Signaling ◽  
Cell Responses

Abstract Interleukin-7 (IL-7) plays a central role in the homeostasis of the T-cell compartment by regulating T-cell survival and proliferation. Whether IL-7 can influence T-cell receptor (TCR) signaling in T cells remains controversial. Here, using IL-7–deficient hosts and TCR-transgenic T cells that conditionally express IL-7R, we examined antigen-specific T-cell responses in vitro and in vivo to viral infection and lymphopenia to determine whether IL-7 signaling influences TCR-triggered cell division events. In vitro, we could find no evidence that IL-7 signaling could costimulate T-cell activation over a broad range of conditions, suggesting that IL-7 does not directly tune TCR signaling. In vivo, however, we found an acute requirement for IL-7 signaling for efficiently triggering T-cell responses to influenza A virus challenge. Furthermore, we found that IL-7 was required for the enhanced homeostatic TCR signaling that drives lymphopenia-induced proliferation by a mechanism involving efficient contacts of T cells with dendritic cells. Consistent with this, saturating antigen-presenting capacity in vivo overcame the triggering defect in response to cognate peptide. Thus, we demonstrate a novel role for IL-7 in regulating T cell–dendritic cell interactions that is essential for both T-cell homeostasis and activation in vivo.

scholarly journals Dasatinib, a small-molecule protein tyrosine kinase inhibitor, inhibits T-cell activation and proliferation

Blood ◽  
2008 ◽  
Vol 111 (3) ◽  
pp. 1366-1377 ◽  
Author(s):  
Andrew E. Schade ◽  
Gary L. Schieven ◽  
Robert Townsend ◽  
Anna M. Jankowska ◽  
Vojkan Susulic ◽  
...  
Keyword(s):  
Signal Transduction ◽  
T Cell ◽  
Small Molecule ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cellular Proliferation ◽  
Kinase Inhibitor ◽  
Tcr Signaling ◽  
Targeted Inhibition

Abstract Dasatinib is an oral small molecule inhibitor of Abl and Src family tyrosine kinases (SFK), including p56Lck (Lck). Given the central importance of Lck in transmitting signals from the T-cell receptor (TCR) signaling complex and the potent ability of dasatinib to inhibit Lck activity, we hypothesized this agent could provide a novel route of immunomodulation via targeted inhibition of antigen-induced signaling. Herein, we show that dasatinib inhibits TCR-mediated signal transduction, cellular proliferation, cytokine production, and in vivo T-cell responses. However, dasatinib-mediated inhibition does not induce apoptosis because the effect is reversible or may be overcome by signals bypassing the TCR, such as phorbol ester. Signal transduction and proliferative responses via IL-2 remain essentially unperturbed, suggesting that dasatinib displays specificity for TCR signaling. In addition, dasatinib combined with cyclosporine A or rapamycin led to a much more potent inhibition of T-cell activation, suggesting that targeted inhibition of Lck could be a useful adjunct for enhanced immunomodulation. In combination with currently available immunomodulatory agents, SFK inhibition could potentially increase immunomodulatory efficacy while minimizing toxicity of individual agents.

scholarly journals Cooperative Inhibition of  T-Cell Antigen Receptor Signaling by a Complex between a Kinase and a Phosphatase

1999 ◽  
Vol 189 (1) ◽  
pp. 111-121 ◽  
Author(s):  
Jean-François Cloutier ◽  
André Veillette
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Tyrosine Kinases ◽  
Cell Activation ◽  
Tyrosine Phosphatase ◽  
Antigen Receptor ◽  
Negative Regulator ◽  
Tcr Signaling ◽  
Protein Tyrosine

Antigen receptor–triggered T-cell activation is mediated by the sequential action of the Src and Syk/Zap-70 families of protein tyrosine kinases (PTKs). Previously, we reported that another PTK termed p50csk was a potent negative regulator of T-cell receptor (TCR) signaling because of its ability to inactivate Src-related kinases. This inhibitory effect required the catalytic activity of Csk, as well as its Src homology (SH)3 and SH2 domains. Subsequent studies uncovered that, via its SH3 domain, p50csk was associated with PEP, a proline-enriched protein tyrosine phosphatase (PTP) of unknown function expressed in hemopoietic cells. Herein, we have attempted to identify the role of the Csk-PEP complex in T lymphocytes. The results of our experiments showed that, like Csk, PEP was a strong repressor of TCR signaling. This property was dependent on the phosphatase activity of PEP, as well as on the sequence mediating its binding to p50csk. Through reconstitution experiments in Cos-1 cells, evidence was obtained that Csk and PEP act synergistically to inhibit protein tyrosine phosphorylation by Src-related kinases, and that this effect requires their association. Finally, experiments with a substrate-trapping mutant of PEP suggested that PEP functions by dephosphorylating and inactivating the PTKs responsible for T-cell activation. In addition to giving novel insights into the mechanisms involved in the negative regulation of T-cell activation, these findings indicate that the association of an inhibitory PTK with a PTP constitutes a more efficient means of inhibiting signal transduction by Src family kinases in vivo.

scholarly journals PAX8 lineage-driven T cell engaging antibody for the treatment of high-grade serous ovarian cancer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Emily Lee ◽  
Sarah Szvetecz ◽  
Ryan Polli ◽  
Angelo Grauel ◽  
Jayson Chen ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Standard Of Care ◽  
Tumor Growth Inhibition ◽  
High Grade ◽  
Ovarian Cancers ◽  
Late Stage Diagnosis ◽  
Anti Tumor Activity

AbstractHigh-grade serous ovarian cancers (HGSOC) represent the most common subtype of ovarian malignancies. Due to the frequency of late-stage diagnosis and high rates of recurrence following standard of care treatments, novel therapies are needed to promote durable responses. We investigated the anti-tumor activity of CD3 T cell engaging bispecific antibodies (TCBs) directed against the PAX8 lineage-driven HGSOC tumor antigen LYPD1 and demonstrated that anti-LYPD1 TCBs induce T cell activation and promote in vivo tumor growth inhibition in LYPD1-expressing HGSOC. To selectively target LYPD1-expressing tumor cells with high expression while sparing cells with low expression, we coupled bivalent low-affinity anti-LYPD1 antigen-binding fragments (Fabs) with the anti-CD3 scFv. In contrast to the monovalent anti-LYPD1 high-affinity TCB (VHP354), the bivalent low-affinity anti-LYPD1 TCB (QZC131) demonstrated antigen density-dependent selectivity and showed tolerability in cynomolgus monkeys at the maximum dose tested of 3 mg/kg. Collectively, these data demonstrate that bivalent TCBs directed against LYPD1 have compelling efficacy and safety profiles to support its use as a treatment for high-grade serous ovarian cancers.

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