scholarly journals T cell activation requires force generation

2016 ◽  
Vol 213 (5) ◽  
pp. 535-542 ◽  
Author(s):  
Kenneth H. Hu ◽  
Manish J. Butte
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Calcium Flux ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Cantilever ◽  
Antigen Presenting

Triggering of the T cell receptor (TCR) integrates both binding kinetics and mechanical forces. To understand the contribution of the T cell cytoskeleton to these forces, we triggered T cells using a novel application of atomic force microscopy (AFM). We presented antigenic stimulation using the AFM cantilever while simultaneously imaging with optical microscopy and measuring forces on the cantilever. T cells respond forcefully to antigen after calcium flux. All forces and calcium responses were abrogated upon treatment with an F-actin inhibitor. When we emulated the forces of the T cell using the AFM cantilever, even these actin-inhibited T cells became activated. Purely mechanical stimulation was not sufficient; the exogenous forces had to couple through the TCR. These studies suggest a mechanical–chemical feedback loop in which TCR-triggered T cells generate forceful contacts with antigen-presenting cells to improve access to antigen.

scholarly journals Mouse T cell priming is enhanced by maturation-dependent stiffening of the dendritic cell cortex

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Daniel Blumenthal ◽  
Vidhi Chandra ◽  
Lyndsay Avery ◽  
Janis K Burkhardt
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Actin Polymerization ◽  
Cell Activation ◽  
Cytoskeletal Proteins ◽  
Cell Cortex ◽  
Force Microscopy ◽  
Atomic Force ◽  
Antigen Presenting

T cell activation by dendritic cells (DCs) involves forces exerted by the T cell actin cytoskeleton, which are opposed by the cortical cytoskeleton of the interacting antigen-presenting cell. During an immune response, DCs undergo a maturation process that optimizes their ability to efficiently prime naïve T cells. Using atomic force microscopy, we find that during maturation, DC cortical stiffness increases via a process that involves actin polymerization. Using stimulatory hydrogels and DCs expressing mutant cytoskeletal proteins, we find that increasing stiffness lowers the agonist dose needed for T cell activation. CD4+ T cells exhibit much more profound stiffness dependency than CD8+ T cells. Finally, stiffness responses are most robust when T cells are stimulated with pMHC rather than anti-CD3ε, consistent with a mechanosensing mechanism involving receptor deformation. Taken together, our data reveal that maturation-associated cytoskeletal changes alter the biophysical properties of DCs, providing mechanical cues that costimulate T cell activation.

scholarly journals Controlling T cells spreading, mechanics and activation by micropatterning

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anaïs Sadoun ◽  
Martine Biarnes-Pelicot ◽  
Laura Ghesquiere-Dierickx ◽  
Ambroise Wu ◽  
Olivier Théodoly ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Young Modulus ◽  
Careful Examination ◽  
Adhesion Receptor ◽  
Force Microscopy ◽  
Atomic Force ◽  
Micro Patterns

AbstractWe designed a strategy, based on a careful examination of the activation capabilities of proteins and antibodies used as substrates for adhering T cells, coupled to protein microstamping to control at the same time the position, shape, spreading, mechanics and activation state of T cells. Once adhered on patterns, we examined the capacities of T cells to be activated with soluble anti CD3, in comparison to T cells adhered to a continuously decorated substrate with the same density of ligands. We show that, in our hand, adhering onto an anti CD45 antibody decorated surface was not affecting T cell calcium fluxes, even adhered on variable size micro-patterns. Aside, we analyzed the T cell mechanics, when spread on pattern or not, using Atomic Force Microscopy indentation. By expressing MEGF10 as a non immune adhesion receptor in T cells we measured the very same spreading area on PLL substrates and Young modulus than non modified cells, immobilized on anti CD45 antibodies, while retaining similar activation capabilities using soluble anti CD3 antibodies or through model APC contacts. We propose that our system is a way to test activation or anergy of T cells with defined adhesion and mechanical characteristics, and may allow to dissect fine details of these mechanisms since it allows to observe homogenized populations in standardized T cell activation assays.

scholarly journals Early T cell receptor signals globally modulate ligand:receptor affinities during antigen discrimination

2017 ◽  
Vol 114 (46) ◽  
pp. 12190-12195 ◽  
Author(s):  
Rafal M. Pielak ◽  
Geoff P. O’Donoghue ◽  
Jenny J. Lin ◽  
Katherine N. Alfieri ◽  
Nicole C. Fay ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Single Molecule ◽  
Cell Activation ◽  
Cell Receptor ◽  
Physical Constraints ◽  
Molecular Binding ◽  
Antigen Presenting

Antigen discrimination by T cells occurs at the junction between a T cell and an antigen-presenting cell. Juxtacrine binding between numerous adhesion, signaling, and costimulatory molecules defines both the topographical and lateral geometry of this cell–cell interface, within which T cell receptor (TCR) and peptide major histocompatibility complex (pMHC) interact. These physical constraints on receptor and ligand movement have significant potential to modulate their molecular binding properties. Here, we monitor individual ligand:receptor binding and unbinding events in space and time by single-molecule imaging in live primary T cells for a range of different pMHC ligands and surface densities. Direct observations of pMHC:TCR and CD80:CD28 binding events reveal that the in situ affinity of both pMHC and CD80 ligands for their respective receptors is modulated by the steady-state number of agonist pMHC:TCR interactions experienced by the cell. By resolving every single pMHC:TCR interaction it is evident that this cooperativity is accomplished by increasing the kinetic on-rate without altering the off-rate and has a component that is not spatially localized. Furthermore, positive cooperativity is observed under conditions where the T cell activation probability is low. This TCR-mediated feedback is a global effect on the intercellular junction. It is triggered by the first few individual pMHC:TCR binding events and effectively increases the efficiency of TCR scanning for antigen before the T cell is committed to activation.

scholarly journals T cell priming is enhanced by maturation-dependent stiffening of the dendritic cell cortex

2019 ◽  
Author(s):  
Daniel Blumenthal ◽  
Lyndsay Avery ◽  
Vidhi Chandra ◽  
Janis K. Burkhardt
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Actin Polymerization ◽  
Cell Activation ◽  
Cytoskeletal Proteins ◽  
Cell Cortex ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cortical Cytoskeleton

ABSTRACTT cell activation by dendritic cells (DCs) involves forces exerted by the T cell actin cytoskeleton, which are opposed by the cortical cytoskeleton of the interacting APC. During an immune response, DCs undergo a maturation process that optimizes their ability to efficiently prime naïve T cells. Using atomic force microscopy, we find that during maturation, DC cortical stiffness increases via process that involves actin polymerization. Using stimulatory hydrogels and DCs expressing mutant cytoskeletal proteins, we find that increasing stiffness lowers the agonist dose needed for T cell activation. CD4+ T cells exhibit much more profound stiffness-dependency than CD8+ T cells. Finally, stiffness responses are most robust when T cells are stimulated with pMHC rather than anti-CD3ε, consistent with a mechanosensing mechanism involving receptor deformation. Taken together, our data reveal that maturation-associated cytoskeletal changes alter the biophysical properties of DCs, providing mechanical cues that costimulate T cell activation.

scholarly journals T cell activation enhancement by endogenous pMHC acts for both weak and strong agonists but varies with differentiation state

2007 ◽  
Vol 204 (11) ◽  
pp. 2747-2757 ◽  
Author(s):  
Pia P. Yachi ◽  
Carina Lotz ◽  
Jeanette Ampudia ◽  
Nicholas R.J. Gascoigne
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
Cd8 T Cell ◽  
Cell Receptor ◽  
Endogenous Peptides ◽  
Foreign Peptide ◽  
Antigen Presenting

T cells are extremely sensitive in their ability to find minute amounts of antigenic peptide in the midst of many endogenous peptides presented on an antigen-presenting cell. The role of endogenous peptides in the recognition of foreign peptide and hence in T cell activation has remained controversial for CD8+ T cell activation. We showed previously that in a CD8+ T cell hybridoma, nonstimulatory endogenous peptides enhance T cell sensitivity to antigen by increasing the coreceptor function of CD8. However, others were not able to detect such enhancement in naive and activated CD8+ T cells. Here, we show that endogenous peptides substantially enhance the ability of T cells to detect antigen, an effect measurable by up-regulation of activation or maturation markers and by increased effector function. This enhancement is most pronounced in thymocytes, moderate in naive T cells, and mild in effector T cells. The importance of endogenous peptides is inversely proportional to the agonist activity of the stimulatory peptide presented. Unlike for CD4+ T cells, the T cell receptor of CD8+ T cells does not distinguish between endogenous peptides for their ability to enhance antigen recognition.

scholarly journals Requirements for Peptide-induced T Cell Receptor Downregulation on Naive CD8+ T Cells

1997 ◽  
Vol 185 (4) ◽  
pp. 641-652 ◽  
Author(s):  
Zeling Cai ◽  
Hidehiro Kishimoto ◽  
Anders Brunmark ◽  
Michael R. Jackson ◽  
Per A. Peterson ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Receptor ◽  
T Cell Activation ◽  
Cell Activation ◽  
Biological Significance ◽  
Cell Receptor ◽  
Metabolic Inhibitors ◽  
Histocompatibility Complex ◽  
Antigen Presenting

The requirements for inducing downregulation of α/β T cell receptor (TCR) molecules on naive major histocompatibility complex class I–restricted T cells was investigated with 2C TCR transgenic mice and defined peptides as antigen. Confirming previous results, activation of 2C T cells in response to specific peptides required CD8 expression on the responder cells and was heavily dependent upon costimulation provided by either B7-1 or ICAM-1 on antigen-presenting cells (APC). These stringent requirements did not apply to TCR downregulation. Thus, TCR downregulation seemed to depend solely on TCR/peptide/interaction and did not require either CD8 or B7-1 expression; ICAM-1 potentiated TCR downregulation, but only with limiting doses of peptides. TCR downregulation was most prominent with high affinity peptides and appeared to be neither obligatory nor sufficient for T cell activation. In marked contrast to T cell activation, TCR downregulation was resistant to various metabolic inhibitors. The biological significance of TCR downregulation is unclear, but could be a device for protecting T cells against excessive signaling.

scholarly journals T-cell activation is modulated by the 3D mechanical microenvironment

2019 ◽  
Author(s):  
Fatemeh S. Majedi ◽  
Mohammad Mahdi Hasani-Sadrabadi ◽  
Timothy J. Thauland ◽  
Song Li ◽  
Louis-S. Bouchard ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Mechanical Stiffness ◽  
Activation Markers ◽  
Cellular Pathways ◽  
And Migration ◽  
Antigen Presenting

AbstractT cells recognize mechanical forces through a variety of cellular pathways, including mechanical triggering of the T-cell receptor (TCR) and mechanical triggering of the integrin LFA-1. We show here that T cells can recognize forces arising from the rigidity of the microenvironment. We fabricated 3D hydrogels with mechanical stiffness tuned to 4 kPa and 40 kPa and specially engineered be microporous independent of stiffness. We cultured T cells and antigen presenting cells within the matrices and studied activation by flow cytometry and live imaging. We found there was an augmentation of T-cell activation in the context of mechanically stiffer 3D material as compared to the softer material. In contrast, proliferation, activation markers, and migration were all diminished in T cells cultured in the softer material. These results show that T cells can sense their mechanical environment and amplify responses in the context of mechanical stiffness.

scholarly journals DNA-based nanoparticle tension sensors reveal that T-cell receptors transmit defined pN forces to their antigens for enhanced fidelity

2016 ◽  
Vol 113 (20) ◽  
pp. 5610-5615 ◽  
Author(s):  
Yang Liu ◽  
Lori Blanchfield ◽  
Victor Pui-Yan Ma ◽  
Rakieb Andargachew ◽  
Kornelia Galior ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Specific Response ◽  
Lymphocyte Function ◽  
Chemomechanical Coupling ◽  
Coreceptor Binding ◽  
Antigen Presenting

T cells are triggered when the T-cell receptor (TCR) encounters its antigenic ligand, the peptide-major histocompatibility complex (pMHC), on the surface of antigen presenting cells (APCs). Because T cells are highly migratory and antigen recognition occurs at an intermembrane junction where the T cell physically contacts the APC, there are long-standing questions of whether T cells transmit defined forces to their TCR complex and whether chemomechanical coupling influences immune function. Here we develop DNA-based gold nanoparticle tension sensors to provide, to our knowledge, the first pN tension maps of individual TCR-pMHC complexes during T-cell activation. We show that naïve T cells harness cytoskeletal coupling to transmit 12–19 pN of force to their TCRs within seconds of ligand binding and preceding initial calcium signaling. CD8 coreceptor binding and lymphocyte-specific kinase signaling are required for antigen-mediated cell spreading and force generation. Lymphocyte function-associated antigen 1 (LFA-1) mediated adhesion modulates TCR-pMHC tension by intensifying its magnitude to values >19 pN and spatially reorganizes the location of TCR forces to the kinapse, the zone located at the trailing edge of migrating T cells, thus demonstrating chemomechanical crosstalk between TCR and LFA-1 receptor signaling. Finally, T cells display a dampened and poorly specific response to antigen agonists when TCR forces are chemically abolished or physically “filtered” to a level below ∼12 pN using mechanically labile DNA tethers. Therefore, we conclude that T cells tune TCR mechanics with pN resolution to create a checkpoint of agonist quality necessary for specific immune response.

scholarly journals Functionalized bead assay to measure 3-dimensional traction forces during T-cell activation

2020 ◽  
Author(s):  
Morteza Aramesh ◽  
Simon Mergenthal ◽  
Marcel Issler ◽  
Birgit Plochberger ◽  
Florian Weber ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Traction Force ◽  
Antigen Recognition ◽  
Traction Force Microscopy ◽  
Superresolution Microscopy ◽  
Force Microscopy ◽  
Antigen Presenting

AbstractWhen T-cells probe their environment for antigens, the bond between the T-cell receptor (TCR) and the peptide-loaded major histocompatibility complex (MHC) is put under tension, thereby influencing the antigen discrimination process. Yet, the quantification of such forces in the context of T-cell signaling is technically challenging. Common approaches such as traction force microscopy (TFM) employ a global readout of the force fields, e.g. by measuring the displacements of hydrogel-embedded marker beads. Recent data, however, indicated that T-cells exert tensile forces locally via TCR-enriched microvilli while scanning the surface of antigen-presenting cells. Here, we developed a traction force microscopy platform, which allows for quantifying the pulls exerted via T-cell microvilli, in both tangential and normal directions, during T-cell activation. For this, we immobilized specific T-cell activating antibodies directly on the marker beads used to read out the hydrogel deformation. Microvilli targeted the functionalized beads, as confirmed by superresolution microscopy of the local actin organization. Moreover, we found that cellular components, such as actin, TCR and CD45 reorganize upon interaction with the beads, such that actin forms a vortex-like ring structure around the beads and TCR is enriched at the bead surface, whereas, CD45 is excluded from bead-microvilli contacts.Significance statementDuring the antigen recognition process, T-cells explore and probe their environment via microvilli, which exert local pushes and pulls at the surface of the antigen presenting cell. It is currently believed that these forces influence or even enable the antigen recognition process. Here, we describe the development of a platform, which allows us to quantify the magnitude and direction of traction forces exerted locally by T cell microvilli. Simultaneous Ca2+ imaging was used to link the measured forces to the overall T cell activation status. Superresolution microscopy resolved the contact sites of bead-microvilli contact at the nanoscale: cells contacted beads via actin vortex-like structures, which excluded the phosphatase CD45 from the contacts.

scholarly journals A role for CD9 molecules in T cell activation.

1996 ◽  
Vol 184 (2) ◽  
pp. 753-758 ◽  
Author(s):  
X G Tai ◽  
Y Yashiro ◽  
R Abe ◽  
K Toyooka ◽  
C R Wood ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
T Cell Activation ◽  
Cell Activation ◽  
Expression Cloning ◽  
Wild Type ◽  
Almost All ◽  
Antigen Presenting ◽  
Deficient Mice

Costimulation mediated by the CD28 molecule plays an important role in optimal activation of T cells. However, CD28-deficient mice can mount effective T cell-dependent immune responses, suggesting the existence of other costimulatory systems. In a search for other costimulatory molecules on T cells, we have developed a monoclonal antibody (mAb) that can costimulate T cells in the absence of antigen-presenting cells (APC). The molecule recognized by this mAb, 9D3, was found to be expressed on almost all mature T cells and to be a protein of approximately 24 kD molecular mass. By expression cloning, this molecule was identified as CD9, 9D3 (anti-CD9) synergized with suboptimal doses of anti-CD3 mAb in inducing proliferation by virgin T cells. Costimulation was induced by independent ligation of CD3 and CD9, suggesting that colocalization of these two molecules is not required for T cell activation. The costimulation by anti-CD9 was as potent as that by anti-CD28. Moreover, anti-CD9 costimulated in a CD28-independent way because anti-CD9 equally costimulated T cells from the CD28-deficient as well as wild-type mice. Thus, these results indicate that CD9 serves as a molecule on T cells that can deliver a potent CD28-independent costimulatory signal.

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