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 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 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 Dynamic microtubules regulate cellular contractility during T-cell activation

2017 ◽  
Vol 114 (21) ◽  
pp. E4175-E4183 ◽  
Author(s):  
King Lam Hui ◽  
Arpita Upadhyaya
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Actin Polymerization ◽  
Cell Activation ◽  
Adaptive Immune Response ◽  
Cell Receptor ◽  
Force Generation ◽  
Actin Dynamics ◽  
Bipolar Filament

T-cell receptor (TCR) triggering and subsequent T-cell activation are essential for the adaptive immune response. Recently, multiple lines of evidence have shown that force transduction across the TCR complex is involved during TCR triggering, and that the T cell might use its force-generation machinery to probe the mechanical properties of the opposing antigen-presenting cell, giving rise to different signaling and physiological responses. Mechanistically, actin polymerization and turnover have been shown to be essential for force generation by T cells, but how these actin dynamics are regulated spatiotemporally remains poorly understood. Here, we report that traction forces generated by T cells are regulated by dynamic microtubules (MTs) at the interface. These MTs suppress Rho activation, nonmuscle myosin II bipolar filament assembly, and actin retrograde flow at the T-cell–substrate interface. Our results suggest a novel role of the MT cytoskeleton in regulating force generation during T-cell activation.

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.

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 Deficiency of Small Gtpase Rac2 Affects T Cell Activation

2001 ◽  
Vol 194 (7) ◽  
pp. 915-926 ◽  
Author(s):  
Hong Yu ◽  
Dave Leitenberg ◽  
Baiyong Li ◽  
Richard A. Flavell
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Transcriptional Activation ◽  
Actin Polymerization ◽  
Cell Activation ◽  
Morphological Changes ◽  
Specific Antigen ◽  
Small Gtpase ◽  
Mitogen Activated Protein Kinase

Rac2 is a hematopoietic-specific GTPase acting as a molecular switch to mediate both transcriptional activation and cell morphological changes. We have examined the effect of Rac2 deficiency during T cell activation. In Rac2−/− T cells, proliferation was reduced upon stimulation with either plate-bound anti-CD3 or T cell receptor–specific antigen. This defect is accompanied with decreased activation of mitogen activated protein kinase extracellular signal–regulated kinase (ERK)1/2 and p38, and reduced Ca2+ mobilization. TCR stimulation–induced actin polymerization is also reduced. In addition, anti-CD3 cross-linking–induced T cell capping is reduced compared with wild-type T cells. These results indicate that Rac2 is important in mediating both transcriptional and cytoskeletal changes during T cell activation. The phenotypic similarity of Rac2−/− to Vav−/− cells implicates Rac2 as a downstream mediator of Vav signaling.

scholarly journals Probiotic supplementation reduces inflammatory profiles but does not prevent oral immune perturbations during SIV infection

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rhianna Jones ◽  
Kyle Kroll ◽  
Courtney Broedlow ◽  
Luca Schifanella ◽  
Scott Smith ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
Rhesus Macaques ◽  
Oral Microbiome ◽  
Probiotic Supplementation ◽  
Siv Infection ◽  
Anti Inflammatory

AbstractHIV/SIV infections lead to massive loss of mucosal CD4 + T cells and breakdown of the epithelial mucosa resulting in severe microbial dysbiosis and chronic immune activation that ultimately drive disease progression. Moreover, disruption of one of the most understudied mucosal environments, the oral cavity, during HIV-induced immunosuppression results in significant microbial and neoplastic co-morbidities and contributes to and predicts distal disease complications. In this study we evaluated the effects of oral probiotic supplementation (PBX), which can stimulate and augment inflammatory or anti-inflammatory pathways, on early SIV infection of rhesus macaques. Our study revealed that similar to the GI mucosae, oral CD4 + T cells were rapidly depleted, and as one of the first comprehensive analyses of the oral microflora in SIV infection, we also observed significant modulation among two genera, Porphyromonas and Actinobacillus, early after infection. Interestingly, although PBX therapy did not substantially protect against oral dysbiosis or ameliorate cell loss, it did somewhat dampen inflammation and T cell activation. Collectively, these data provide one of the most comprehensive evaluations of SIV-induced changes in oral microbiome and CD4 + T cell populations, and also suggest that oral PBX may have some anti-inflammatory properties in lentivirus infections.

scholarly journals Deep immune profiling of MIS-C demonstrates marked but transient immune activation compared to adult and pediatric COVID-19

2021 ◽  
Vol 6 (57) ◽  
pp. eabf7570
Author(s):  
Laura A. Vella ◽  
Josephine R. Giles ◽  
Amy E. Baxter ◽  
Derek A. Oldridge ◽  
Caroline Diorio ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Immune Activation ◽  
Cell Activation ◽  
Vascular Complications ◽  
Adult Disease ◽  
Vasoactive Medication ◽  
Inflammatory Syndrome

Pediatric COVID-19 following SARS-CoV-2 infection is associated with fewer hospitalizations and often milder disease than in adults. A subset of children, however, present with Multisystem Inflammatory Syndrome in Children (MIS-C) that can lead to vascular complications and shock, but rarely death. The immune features of MIS-C compared to pediatric COVID-19 or adult disease remain poorly understood. We analyzed peripheral blood immune responses in hospitalized SARS-CoV-2 infected pediatric patients (pediatric COVID-19) and patients with MIS-C. MIS-C patients had patterns of T cell-biased lymphopenia and T cell activation similar to severely ill adults, and all patients with MIS-C had SARS-CoV-2 spike-specific antibodies at admission. A distinct feature of MIS-C patients was robust activation of vascular patrolling CX3CR1+ CD8+ T cells that correlated with the use of vasoactive medication. Finally, whereas pediatric COVID-19 patients with acute respiratory distress syndrome (ARDS) had sustained immune activation, MIS-C patients displayed clinical improvement over time, concomitant with decreasing immune activation. Thus, non-MIS-C versus MIS-C SARS-CoV-2 associated illnesses are characterized by divergent immune signatures that are temporally distinct from one another and implicate CD8+ T cells in the clinical presentation and trajectory of MIS-C.

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