Dialogue entre Cellules T et Cellules Dendritiques

Publications de l’équipe

Année de publication : 2017

Anna Sawicka, Avin Babataheri, Stéphanie Dogniaux, Abdul I Barakat, David Gonzalez-Rodriguez, Claire Hivroz, Julien Husson (2017 Sep 22)

Micropipette Force Probe to quantify single-cell force generation: application to T cell activation.

Molecular biology of the cell : DOI : mbc.E17-06-0385 En savoir plus
Résumé

In response to engagement of surface molecules, cells generate active forces that regulate many cellular processes. Developing tools that permit gathering mechanical and morphological information on these forces is of the utmost importance. Here we describe a new technique, the Micropipette Force Probe, that uses a micropipette as a flexible cantilever that can aspirate at its tip a bead that is coated with molecules of interest and is brought in contact with the cell. This technique simultaneously allows tracking the resulting changes in cell morphology and mechanics as well as measuring the forces generated by the cell. To illustrate the power of this technique, we applied it to the study of human primary T lymphocytes (T cells). It allowed the fine monitoring of pushing and pulling forces generated by T cells in response to various activating antibodies and bending stiffness of the micropipette. We further dissected the sequence of mechanical and morphological events occurring during T cell activation to model force generation and to reveal heterogeneity in the cell population studied. We also report the first measurement of the changes in Young’s modulus of T cells during their activation, showing that T cells stiffen within the first minutes of the activation process.

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Michael Saitakis, Stéphanie Dogniaux, Christel Goudot, Nathalie Bufi, Sophie Asnacios, Mathieu Maurin, Clotilde Randriamampita, Atef Asnacios, Claire Hivroz (2017 Jun 9)

Different TCR-induced T lymphocyte responses are potentiated by stiffness with variable sensitivity.

eLife : DOI : 10.7554/eLife.23190 En savoir plus
Résumé

T cells are mechanosensitive but the effect of stiffness on their functions is still debated. We characterize herein how human primary CD4(+) T cell functions are affected by stiffness within the physiological Young’s modulus range of 0.5 kPa to 100 kPa. Stiffness modulates T lymphocyte migration and morphological changes induced by TCR/CD3 triggering. Stiffness also increases TCR-induced immune system, metabolism and cell-cycle-related genes. Yet, upon TCR/CD3 stimulation, while cytokine production increases within a wide range of stiffness, from hundreds of Pa to hundreds of kPa, T cell metabolic properties and cell cycle progression are only increased by the highest stiffness tested (100 kPa). Finally, mechanical properties of adherent antigen-presenting cells modulate cytokine production by T cells. Together, these results reveal that T cells discriminate between the wide range of stiffness values found in the body and adapt their responses accordingly.

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Claire Hivroz, Paola Larghi, Mabel Jouve, Laurence Ardouin (2017 Mar 4)

Purification of LAT-Containing Membranes from Resting and Activated T Lymphocytes.

Methods in molecular biology (Clifton, N.J.) : 355-368 : DOI : 10.1007/978-1-4939-6881-7_21 En savoir plus
Résumé

In T lymphocytes, the immune synapse is an active zone of vesicular traffic. Directional transport of vesicular receptors and signaling molecules from or to the immune synapse has been shown to play an important role in T-cell receptor (TCR) signal transduction. However, how vesicular trafficking is regulating the activation of T cells is still a burning question, and the characterization of these intracellular compartments remains the first step to understand this process. We describe herein a protocol, which combines a separation of membranes on flotation gradient with an affinity purification of Strep-tagged fusion transmembrane proteins with Strep-Tactin(®) resin, allowing the purification of membranes containing the Strep-tagged molecule of interest. By keeping the membranes intact, this protocol leads to the purification of molecules physically associated with the Strep-tagged protein as well as of molecules present in the same membrane compartment: transmembrane proteins, proteins strongly associated with the membranes, and luminal proteins. The example shown herein is the purification of membrane compartment prepared from T lymphocytes expressing LAT fused to a Strep-tag.

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Année de publication : 2016

Asma Beldi-Ferchiou, Marion Lambert, Stéphanie Dogniaux, Frédéric Vély, Eric Vivier, Daniel Olive, Stéphanie Dupuy, Frank Levasseur, David Zucman, Céleste Lebbé, Damien Sène, Claire Hivroz, Sophie Caillat-Zucman (2016 Sep 24)

PD-1 mediates functional exhaustion of activated NK cells in patients with Kaposi sarcoma.

Oncotarget : DOI : 10.18632/oncotarget.12150 En savoir plus
Résumé

Programmed Death-1 (PD-1), an inhibitory receptor expressed by activated lymphocytes, is involved in regulating T- and B-cell responses. PD-1 and its ligands are exploited by a variety of cancers to facilitate tumor escape through PD-1-mediated functional exhaustion of effector T cells. Here, we report that PD-1 is upregulated on Natural Killer (NK) cells from patients with Kaposi sarcoma (KS). PD-1 was expressed in a sub-population of activated, mature CD56dimCD16pos NK cells with otherwise normal expression of NK surface receptors. PD-1pos NK cells from KS patients were hyporesponsive ex vivo following direct triggering of NKp30, NKp46 or CD16 activating receptors, or short stimulation with NK cell targets. PD-1pos NK cells failed to degranulate and release IFNγ, but exogenous IL-2 or IL-15 restored this defect. That PD-1 contributed to NK cell functional impairment and was not simply a marker of dysfunctional NK cells was confirmed in PD-1-transduced NKL cells. In vitro, PD-1 was induced at the surface of healthy control NK cells upon prolonged contact with cells expressing activating ligands, i.e. a condition mimicking persistent stimulation by tumor cells. Thus, PD-1 appears to plays a critical role in mediating NK cell exhaustion. The existence of this negative checkpoint fine-tuning NK activation highlights the possibility that manipulation of the PD-1 pathway may be a strategy for circumventing tumor escape not only from the T cell-, but also the NK-cell mediated immune surveillance.

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