scholarly journals Beta-1,3 Oligoglucans Specifically Bind to Immune Receptor CD28 and May Enhance T Cell Activation

2021 ◽  
Vol 22 (6) ◽  
pp. 3124
Author(s):  
Jeffrey Comer ◽  
Molly Bassette ◽  
Riley Burghart ◽  
Mayme Loyd ◽  
Susumu Ishiguro ◽  
...  
Keyword(s):  
Free Energy ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Binding Free Energy ◽  
Receptor Activation ◽  
Free Energy Calculations ◽  
Mrna Levels ◽  
Immunostimulatory Activity ◽  
Immune Receptor

Beta glucans are known to have immunomodulatory effects that mediated by a variety of mechanisms. In this article, we describe experiments and simulations suggesting that beta-1,3 glucans may promote activation of T cells by a previously unknown mechanism. First, we find that treatment of a T lymphoblast cell line with beta-1,3 oligoglucan significantly increases mRNA levels of T cell activation-associated cytokines, especially in the presence of the agonistic anti-CD3 antibody. This immunostimulatory activity was observed in the absence of dectin-1, a known receptor for beta-1,3 glucans. To clarify the molecular mechanism underlying this activity, we performed a series of molecular dynamics simulations and free-energy calculations to explore the interaction of beta-1,3 oligoglucans with potential immune receptors. While the simulations reveal little association between beta-1,3 oligoglucan and the immune receptor CD3, we find that beta-1,3 oligoglucans bind to CD28 near the region identified as the binding site for its natural ligands CD80 and CD86. Using a rigorous absolute binding free-energy technique, we calculate a dissociation constant in the low millimolar range for binding of 8-mer beta-1,3 oligoglucan to this site on CD28. The simulations show this binding to be specific, as no such association is computed for alpha-1,4 oligoglucan. This study suggests that beta-1,3 glucans bind to CD28 and may stimulate T cell activation collaboratively with T cell receptor activation, thereby stimulating immune function.

Experimental silicosis: a shift to a preferential IFN-γ-based Th1 response in thoracic lymph nodes

2000 ◽  
Vol 278 (6) ◽  
pp. L1221-L1230 ◽  
Author(s):  
Holger Garn ◽  
Anke Friedetzky ◽  
Andrea Kirchner ◽  
Ruth Jäger ◽  
Diethard Gemsa
Keyword(s):  
T Cell ◽  
Lymph Nodes ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cytotoxic T Cell ◽  
Mrna Levels ◽  
Ifn Γ

In chronic silicosis, mechanisms leading to lymphocyte activation are still poorly understood, although it is well known that not only the lung but also the draining lymph nodes are affected. In the present study, we investigated T-cell activation by analysis of cytokine expression in the enlarged thoracic lymph nodes of rats 2 mo after an 8-day silica aerosol exposure. In the case of helper T cell (Th) type 1 cytokines, we found a significant increase in interferon (IFN)-γ mRNA expression, whereas interleukin (IL)-2 expression remained unchanged. In contrast, gene transcription for the Th2-type cytokines IL-4 and IL-10 was diminished. In addition, with use of an in vitro lymphocyte-macrophage coculture system, an enhanced IFN-γ and a reduced IL-10 release were shown with cells from silicotic animals. With regard to IFN-γ-inducing cytokines, we observed enhanced IL-12 mRNA levels in vivo, whereas IL-18 gene expression was slightly decreased. These data indicate that a persistent shift toward an IFN-γ-dominated type 1 (Th1/cytotoxic T cell type 1) T-cell reaction pattern occurred within the thoracic lymph nodes of silicotic animals. Thus a mutual activation of lymphocytes and macrophages may maintain the chronic inflammatory changes that characterize silicosis.

scholarly journals Human T cell activation. IV. T cell activation and proliferation via the early activation antigen EA 1.

1989 ◽  
Vol 169 (3) ◽  
pp. 677-689 ◽  
Author(s):  
S Nakamura ◽  
S S Sung ◽  
J M Bjorndahl ◽  
S M Fu
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Early Activation ◽  
Human T Cell ◽  
Accessory Cells ◽  
Activation Antigen

A new mAb G38 was generated against purified EA 1, an early activation antigen. In immunoprecipitation, it was reactive with the same complex precipitated by the initial anti-EA 1 mAb P8. mAb G38 augmented PMA-induced proliferation of PBMC. It was shown to be mitogenic for purified T cells in collaboration with PMA in a dose-dependent manner. This effect was independent of monocytes and other accessory cells. mAb G38 augmented PMA-induced IL-2-R expression. In conjunction with PMA, it induced IL-2 synthesis and secretion. Its effects on IL-2-R and IL-2 expression were documented at both protein and mRNA levels. Both anti-EA 1 mAbs did not induce Ca2+ influx by themselves in PMA-treated T cells. However, the addition of second anti-mouse Ig antibodies induced readily detectable increases in [Ca2+]i. Ca2+-mediated pathways may be utilized as the transduction signal mechanisms. mAb Leu-23 was shown to be reactive with EA 1. mAb Leu-23 was also mitogenic for T cells in the presence of PMA. These findings provide evidence for a functional role for EA 1 in T cell activation and proliferation.

scholarly journals Induction of c-ets and c-fos gene expression upon antigenic stimulation of a T cell hybridoma with inducible cytolytic capacity.

1987 ◽  
Vol 166 (3) ◽  
pp. 810-815 ◽  
Author(s):  
Y Kaufmann ◽  
T Silverman ◽  
B Z Levi ◽  
K Ozato
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Specific Antigen ◽  
Functional Differentiation ◽  
Mrna Levels ◽  
Cellular Oncogenes ◽  
Differentiation Of Lymphocytes ◽  
Stimulation Of

Expression of cellular oncogenes was studied in a T cell hybridoma that undergoes cytolytic activation when stimulated by specific antigen or by anti-Thy-1 antibody. The activation occurs without induction of hybridoma proliferation, providing a model to examine oncogene expression during functional differentiation of lymphocytes. We found that c-fos and c-ets-1 mRNAs were transiently induced at high levels in the hybridoma 30 min and 4 h after stimulation, respectively. c-myc and c-ets-2 oncogenes were constitutively expressed in the hybridoma and their mRNA levels were unaffected during 4 h of stimulation, although c-myc expression was reduced in the later stage of stimulation. Inhibitors of T cell activation, cyclosporin A and anti-LFA-1 antibody, blocked the induction of c-fos and c-ets-1 mRNAs without reducing the levels of c-myc and c-ets-2. The results indicate that the functional activation of the CTL hybridoma is associated with induction of c-fos and c-ets-1 genes.

scholarly journals Three-Dimensional Model of Sub-Plasmalemmal Ca2+ Microdomains Evoked by the Interplay Between ORAI1 and InsP3 Receptors

2021 ◽  
Vol 12 ◽  
Author(s):  
Diana Gil ◽  
Andreas H. Guse ◽  
Geneviève Dupont
Keyword(s):  
T Cells ◽  
Cell Adhesion ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Three Dimensional ◽  
Receptor Activation ◽  
Reaction Diffusion Model ◽  
Activated State ◽  
T Cell Adhesion

Ca2+ signaling plays an essential role in T cell activation, which is a key step to start an adaptive immune response. During the transition from a quiescent to a fully activated state, Ca2+ microdomains characterized by reduced spatial and temporal extents are observed in the junctions between the plasma membrane (PM) and the endoplasmic reticulum (ER). Such Ca2+ responses can also occur in response to T cell adhesion to other cells or extracellular matrix proteins in otherwise unstimulated T cells. These non-TCR/CD3-dependent Ca2+ microdomains rely on d-myo-inositol 1,4,5-trisphosphate (IP3) signaling and subsequent store operated Ca2+ entry (SOCE) via the ORAI/STIM system. The detailed molecular mechanism of adhesion-dependent Ca2+ microdomain formation remains to be fully elucidated. We used mathematical modeling to investigate the spatiotemporal characteristics of T cell Ca2+ microdomains and their molecular regulators. We developed a reaction-diffusion model using COMSOL Multiphysics to describe the evolution of cytosolic and ER Ca2+ concentrations in a three-dimensional ER-PM junction. Equations are based on a previously proposed realistic description of the junction, which is extended to take into account IP3 receptors (IP3R) that are located next to the junction. The first model only considered the ORAI channels and the SERCA pumps. Taking into account the existence of preformed clusters of ORAI1 and STIM2, ORAI1 slightly opens in conditions of a full ER. These simulated Ca2+ microdomains are too small as compared to those observed in unstimulated T cells. When considering the opening of the IP3Rs located near the junction, the local depletion of ER Ca2+ allows for larger Ca2+ fluxes through the ORAI1 channels and hence larger local Ca2+ concentrations. Computational results moreover show that Ca2+ diffusion in the ER has a major impact on the Ca2+ changes in the junction, by affecting the local Ca2+ gradients in the sub-PM ER. Besides pointing out the likely involvement of the spontaneous openings of IP3Rs in the activation of SOCE in conditions of T cell adhesion prior to full activation, the model provides a tool to investigate how Ca2+ microdomains extent and interact in response to T cell receptor activation.

scholarly journals 798 CDX-585, A bispecific antibody with dual targeting of ILT4 and PD-1 checkpoint pathways

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A833-A833
Author(s):  
Laura Vitale ◽  
Michael Murphy ◽  
Collin Xia ◽  
Zeyu Peng ◽  
Thomas O'Neill ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Clinical Chemistry ◽  
Primary Cultures ◽  
Resistance Mechanism ◽  
Myeloid Cell ◽  
Receptor Activation ◽  
Pilot Studies ◽  
Enhanced Production

BackgroundActivation of the ITIM-bearing ILT4/LILRB2 receptor by its cognate ligands (HLA-G and HLA Class I) has been postulated as a resistance mechanism for checkpoint blockade of PD-1 and CTLA-4. Dual inhibition of receptors that suppress myeloid and T cell compartments through the generation of bispecific antibodies (bsAbs) is a promising strategy to improve outcomes for patients whose tumors are resistant to checkpoint inhibition.MethodsWe describe the discovery and characterization of CDX-585 a bsAb developed from novel ILT4 and PD-1 antagonist mAbs that revert myeloid cell suppression by antagonizing ILT4 and activating T-cell responses through PD-1 inhibition. The bsAb was engineered as a tetravalent molecule using the PD-1 IgG1 mAb linked to scFv of the ILT4 mAb at the C-terminus of the heavy chain. A series of mutations were introduced in the Fc domain to eliminate Fcy receptor binding and increase affinity to the neonatal Fc receptor. CDX-585 has good biophysical characteristics and retains functional properties similar to, or better, than the parental mAbs.ResultsCDX-585 has sub-nanomolar affinity binding to ILT4 and PD-1 and is a potent competitor of their respective ligands. Primary cultures of human macrophages and dendritic cells treated with CDX-585 enhanced production of inflammatory cytokines/chemokines, which was further potentiated in the presence of toll like receptor activation with lipopolysaccharide (LPS). CDX-585 was particularly effective in promoting T cell activation as measured by mixed lymphocyte reactions, and in polarizing macrophages towards M1 based on their cytokine profile. Pilot studies in mice and cynomolgus macaques confirmed a favorable pharmacokinetic profile without adverse effects of treatment noted in clinical observations or clinical chemistry.ConclusionsCDX-585 effectively combines ILT4 and PD-1 blockade into one molecule with favorable biophysical and functional characteristics supporting the initiation of development activities including manufacturing and IND-enabling studies.

scholarly journals Combining Well-Tempered Metadynamics Simulation and SPR Assays to Characterize the Binding Mechanism of the Universal T-Lymphocyte Tetanus Toxin Epitope TT830-843

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Artur A. M. L. Brandt ◽  
Rodrigo N. Rodrigues-da-Silva ◽  
Josué C. Lima-Junior ◽  
Carlos R. Alves ◽  
Franklin de Souza-Silva
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
T Cell ◽  
T Cell Activation ◽  
Tetanus Toxin ◽  
Cell Activation ◽  
Cell Epitope ◽  
In Vitro Assays ◽  
Stable Complex ◽  
Free Energy Surface

Peptide TT830-843 from the tetanus toxin is a universal T-cell epitope. It helps in vaccination and induces T-cell activation. However, the fine molecular interaction between this antigen and the major histocompatibility complex (MHC) remains unknown. Molecular analysis of its interaction with murine MHC (H-2) was proposed to explore its immune response efficiency. Molecular dynamics simulations are important mechanisms for understanding the basis of protein-ligand interactions, and metadynamics is a useful technique for enhancing sampling in molecular dynamics. SPR (surface plasmon resonance) assays were used to validate whether the metadynamics results are in accordance with the experimental results. The peptide TT830-843 unbinding process was simulated, and the free energy surface reconstruction revealed a detailed conformational landscape. The simulation described the exiting path as a stepwise mechanism between progressive detachment states. We pointed out how the terminus regions act as anchors for binding and how the detachment mechanism includes the opening of α-helices to permit the peptide’s central region dissociation. The results indicated the peptide/H-2 receptor encounter occurs within a distance lesser than 27.5 Å, and the encounter can evolve to form a stable complex. SPR assays confirmed the complex peptide/H-2 as a thermodynamically stable system, exhibiting enough free energy to interact with TCR on the antigen-presenting cell surface. Therefore, combining in silico and in vitro assays provided significant evidence to support the peptide/H-2 complex formation.

scholarly journals Reduced interferon-gamma mRNA levels in human neonates. Evidence for an intrinsic T cell deficiency independent of other genes involved in T cell activation.

1986 ◽  
Vol 163 (4) ◽  
pp. 1018-1023 ◽  
Author(s):  
D B Lewis ◽  
A Larsen ◽  
C B Wilson
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Mononuclear Cells ◽  
Mrna Levels ◽  
Con A ◽  
Ifn Gamma ◽  
Neonatal Blood ◽  
Human Neonates

IFN-gamma mRNA levels in human neonatal blood mononuclear cells or highly purified T cells were markedly lower than those of adult cells after incubation with Con A and PMA. In contrast, IL-2, IL-2-R, and T3 delta chain mRNA levels were kinetically and quantitatively similar in neonatal and adult T cells. The peak amount of IFN-gamma and IL-2 mRNA correlated well with IFN-gamma and IL-2 detected in supernatants of both neonatal and adult T cells. These results suggest that reduced IFN-gamma mRNA levels in neonatal T cells is due to an intrinsic deficiency at the pretranslational level and indicate that the magnitude of IL-2 and IFN-gamma gene expression can be independently modulated pretranslationally.

scholarly journals 879 A promising cancer immunotherapy target: novel fully human agonist antibodies against the human T-cell costimulatory receptor CD27

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A921-A921
Author(s):  
Thierry Guillaudeux ◽  
Yulia Ovechkina ◽  
Shaarwari Sridhar ◽  
David Jurchen ◽  
David Peckham ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cancer Immunotherapy ◽  
T Cell Activation ◽  
Cell Activation ◽  
Receptor Activation ◽  
Cytotoxic T Cell ◽  
T Cell Proliferation ◽  
List Type

BackgroundCD27 is a member of the TNF receptor superfamily and plays a critical role in T-cell activation by providing a costimulatory signal. CD27 signaling enhances T-cell proliferation, activation and differentiation of effector and memory T cells and therefore promotes cytotoxic T cell (CTL)-based anti-tumor immunity.1 Agonistic stimulation of CD27 is a promising cancer immunotherapy approach to boost specific T cell driven anti-tumor responses.MethodsIn this study, we generated a series of 147 fully human monoclonal anti-CD27 antibodies and tested their agonist properties to stimulate T cell activation.ResultsUsing a NF-κB reporter Jurkat cell line, we evaluated in vitro the ability of anti-CD27 antibodies to induce CD27 receptor activation. With this assay, five antibodies have been selected for their agonist properties. When combined with suboptimal T cell receptor (TCR) stimulation, agonist antibodies induced CD27 receptor activation with an EC50 of 1–5 ug/mL. We also used human peripheral blood T cells to characterize the CD27-mediated costimulatory effects of agonist antibodies in combination with TCR stimulation. Our anti-CD27 monoclonal antibodies boosted T cell proliferation and induced IL-2 and TNFalpha secretion only in a presence of TCR engagement. Moreover, CD27 agonists induce strong T cell proliferation in a Mixed Lymphocyte Reaction. CD27 antibodies were shown to bind human and cynomolgus monkey CD27 with a KD value of 5–20 nM as determined by BioLayer Interferometry, but do not bind to mouse CD27. In vivo experiments are currently ongoing to demonstrate the efficient anti-tumor activity of the selected CD27 agonist antibodies in different mice tumor models.ConclusionsIn conclusion, we have developed and successfully selected efficient fully human immuno-stimulatory agonist CD27 mAbs as a promising cancer immunotherapy.ReferenceHendriks J, Xiao Y, Borst J. CD27 promotes survival of activated T cells and complements CD28 in generation and establishment of the effector T cell pool. J Exp Med 2003;Volume 198, Number 9:1369–1380.

scholarly journals Polysaccharide of Atractylodes macrocephala Koidz (PAMK) Alleviates Cyclophosphamide-induced Immunosuppression in Mice by Upregulating CD28/IP3R/PLCγ-1/AP-1/NFAT Signal Pathway

2020 ◽  
Vol 11 ◽  
Author(s):  
Xuelian Xiang ◽  
Nan Cao ◽  
Feiyue Chen ◽  
Long Qian ◽  
Yifei Wang ◽  
...  
Keyword(s):  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Signal Pathway ◽  
Th2 Cells ◽  
Mrna Levels ◽  
Activation Level ◽  
Tnf Α ◽  
Atractylodes Macrocephala ◽  
Spleen Index

The polysaccharide of Atractylodes macrocephala Koidz (PAMK) is recognized as an immune enhancer, with anti-cancer, anti-tumour, lymphocyte-activating and lymphocytes proliferation-inducing effects. For investigating the mechanism that PAMK alleviates the decline in T cell activation induced by CTX, 24 6-week-old BALB/c female mice were randomly divided into four groups (C, PAMK, CTX, PAMK + CTX). The spleen index, splenocytes morphology and death, cytokine concentration, T cell activating factors (CD25, CD69, CD71), mRNA expression levels related to the CD28 signal pathway were detected. Furthermore, the lymphocytes of mice was isolated and cultured, and then the Th1/Th2 ratio, activating factors, mRNA levels related to the CD28 signal pathway were detected. The results showed that PAMK significantly improved the spleen index, alleviated abnormal splenocytes morphology and death, maintained the balance of Th1/Th2 cells, increased the levels of IL-2, IL-6, TNF-α, and IFN-γ, and increased the mRNA levels of CD28, PLCγ-1, IP3R, NFAT, and AP-1. In conclusion, PAMK increased cytokines levels and alleviated the decline in activation level of lymphocytes induced by CTX through CD28/IP3R/PLCγ-1/AP-1/NFAT signal pathway.

WIP-Mediated Mechanisms of Recruitment, Activation and Degradation of WASP in T Cells.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 599-599
Author(s):  
Yoji Sasahara ◽  
Narayanaswamy Ramesh ◽  
Shigeru Tsuchiya ◽  
Raif S. Geha
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Actin Polymerization ◽  
Cell Activation ◽  
Immunological Synapse ◽  
Critical Role ◽  
Mrna Levels ◽  
Missense Mutations ◽  
Deficient Mice

Abstract WASP, the product of the gene mutated in Wiskott-Aldrich syndrome (WAS), plays a critical role in T cell activation and actin reorganization. WIP is a WASP-interacting protein that binds to EVH1 domain of WASP, and negatively regulates WASP functions. WASP-mediated actin polymerization and cytoskeletal remodeling are critical for immunological synapse (IS) formation between T cells and antigen presenting cells. To clarify the functions of WIP in T cells, we investigated WIP-mediated mechanisms of recruitment, activation and degradation of WASP following T cell receptor (TCR) ligation and IS formation. WASP translocates to lipid rafts following TCR ligation and localizes at the IS between T cells and B cells presenting superantigen. WASP recruitment is regulated by several TCR signaling pathways mediated by ZAP70-CrkL-WIP and ZAP70-SLP76-Nck complexes. After the recruitment of WASP, WIP is serine-phosphorylated by PKCtheta localized at the IS, and phosphorylated WIP dissociates from WASP, releasing WASP from WIP inhibition. A fraction of WASP is fragmented by Ca-dependent protease calpain and ubiquitinated by Cbl-b, then degraded by the proteasome following TCR ligation. Inhibition of PKCtheta-mediated dissociation of the WASP-WIP complex inhibits WASP degradation. Inhibition of proteasomal degradation results in the accumulation of WASP fragments and enhanced TCR-induced actin polymerization in normal T cells. We demonstrate that WASP protein, but not mRNA, levels are severely diminished in T cells from WIP-deficient mice, but are restored by calpain and proteasome inhibitors. These inhibitors restore WASP protein levels and correct the defect in actin polymerization in response to TCR ligation in T cells from a WAS patient with a missense mutation that disrupts WIP binding. The similarity of the functional defects in WASP- and WIP-deficient mice and the observation that most missense mutations in WAS patients are in the WIP binding EVH1 domain of WASP suggest that WIP may function as a chaperone that controls WASP levels in T cells. These results suggest that WIP is involved in the recruitment and activation of WASP and that degradation of WASP freed from WIP may down-regulate actin polymerization following TCR ligation. More importantly, WIP regulates WASP protein stability in T cells from WAS patients with WASP missense mutations in WIP-binding site and impaired WASP-WIP interaction.

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