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2.
Int Immunol ; 31(4): 239-250, 2019 03 28.
Artigo em Inglês | MEDLINE | ID: mdl-30778577

RESUMO

The intrinsic immunosuppressive properties of regulatory T (Treg) cells can be harnessed for therapeutic approaches aiming at down-modulating harmful immune reactions. In this context, expanded type 1 Treg cells (Tr1 cells) specific for ovalbumin (ova-Tr1 cells) have been tested for clinical efficacy in the treatment of autoimmune disorders such as refractory Crohn's disease (CD). The clinical use of these therapeutic products warrants exploration of their mechanism of action. Here, we identified a relationship between the CD activity index and the expression of lytic molecules by the ova-Tr1 cells administered in the previously reported First-in-Man study [Crohn's And Treg cells Study 1 (CATS1) study]. Accordingly, ova-Tr1 cells were found to carry granules containing high levels of lytic molecules, including multiple granzymes and granulysin. These cells displayed a T-cell receptor (TCR)-independent cytotoxic activity, which was preferentially directed toward myeloid cell lines and monocyte-derived dendritic cells. Upon contact with myeloid cells, ova-Tr1 cells induced their apoptosis via a perforin-independent and a granulysin/granzyme-dependent mechanism. As compared to CD8+ cytotoxic T cells, ova-Tr1 cells required more time to lyse target cells and displayed a more gradual lytic activity over time. Notably, this activity was sustained over days resulting in the control of myeloid cell populations at a relatively low ratio. Our study reveals that ova-Tr1 cells are endowed with a sustained cytotoxic activity that relies on a unique combination of granulysin and granzymes and that preferentially eliminates myeloid target cells in a TCR-independent manner.

3.
Blood ; 132(22): 2362-2374, 2018 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-30254128

RESUMO

ARPC1B is a key factor for the assembly and maintenance of the ARP2/3 complex that is involved in actin branching from an existing filament. Germline biallelic mutations in ARPC1B have been recently described in 6 patients with clinical features of combined immunodeficiency (CID), whose neutrophils and platelets but not T lymphocytes were studied. We hypothesized that ARPC1B deficiency may also lead to cytoskeleton and functional defects in T cells. We have identified biallelic mutations in ARPC1B in 6 unrelated patients with early onset disease characterized by severe infections, autoimmune manifestations, and thrombocytopenia. Immunological features included T-cell lymphopenia, low numbers of naïve T cells, and hyper-immunoglobulin E. Alteration in ARPC1B protein structure led to absent/low expression by flow cytometry and confocal microscopy. This molecular defect was associated with the inability of patient-derived T cells to extend an actin-rich lamellipodia upon T-cell receptor (TCR) stimulation and to assemble an immunological synapse. ARPC1B-deficient T cells additionally displayed impaired TCR-mediated proliferation and SDF1-α-directed migration. Gene transfer of ARPC1B in patients' T cells using a lentiviral vector restored both ARPC1B expression and T-cell proliferation in vitro. In 2 of the patients, in vivo somatic reversion restored ARPC1B expression in a fraction of lymphocytes and was associated with a skewed TCR repertoire. In 1 revertant patient, memory CD8+ T cells expressing normal levels of ARPC1B displayed improved T-cell migration. Inherited ARPC1B deficiency therefore alters T-cell cytoskeletal dynamics and functions, contributing to the clinical features of CID.

4.
J Allergy Clin Immunol ; 142(5): 1589-1604.e11, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29751004

RESUMO

BACKGROUND: The actin-interacting protein WD repeat-containing protein 1 (WDR1) promotes cofilin-dependent actin filament turnover. Biallelic WDR1 mutations have been identified recently in an immunodeficiency/autoinflammatory syndrome with aberrant morphology and function of myeloid cells. OBJECTIVE: Given the pleiotropic expression of WDR1, here we investigated to what extent it might control the lymphoid arm of the immune system in human subjects. METHODS: Histologic and detailed immunologic analyses were performed to elucidate the role of WDR1 in the development and function of B and T lymphocytes. RESULTS: Here we identified novel homozygous and compound heterozygous WDR1 missense mutations in 6 patients belonging to 3 kindreds who presented with respiratory tract infections, skin ulceration, and stomatitis. In addition to defective adhesion and motility of neutrophils and monocytes, WDR1 deficiency was associated with aberrant T-cell activation and B-cell development. T lymphocytes appeared to develop normally in the patients, except for the follicular helper T-cell subset. However, peripheral T cells from the patients accumulated atypical actin structures at the immunologic synapse and displayed reduced calcium flux and mildly impaired proliferation on T-cell receptor stimulation. WDR1 deficiency was associated with even more severe abnormalities of the B-cell compartment, including peripheral B-cell lymphopenia, paucity of B-cell progenitors in the bone marrow, lack of switched memory B cells, reduced clonal diversity, abnormal B-cell spreading, and increased apoptosis on B-cell receptor/Toll-like receptor stimulation. CONCLUSION: Our study identifies a novel role for WDR1 in adaptive immunity, highlighting WDR1 as a central regulator of actin turnover during formation of the B-cell and T-cell immunologic synapses.

5.
Sci Rep ; 8(1): 5800, 2018 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-29643414

RESUMO

Lymphocytes alternate between phases of individual migration across tissues and phases of clustering during activation and function. The range of lymphocyte motility behaviors and the identity of the factors that govern them remain elusive. To explore this point, we here collected unprecedented statistics pertaining to cell displacements, cell:matrix and cell:cell interactions using a model B cell line as well as primary human B lymphocytes. At low cell density, individual B lymphocytes displayed a high heterogeneity in their speed and diffusivity. Beyond this intrinsic variability, B lymphocytes adapted their motility to the composition of extra-cellular matrix, adopting slow persistent walks over collagen IV and quick Brownian walks over fibronectin. At high cell density, collagen IV favored the self-assembly of B lymphocytes into clusters endowed with collective coordination, while fibronectin stimulated individual motility. We show that this behavioral plasticity is controlled by acto-myosin dependent adhesive and Arp2/3-dependent protrusive actin pools, respectively. Our study reveals the adaptive nature of B lymphocyte motility and group dynamics, which are shaped by an interplay between and cell:matrix and cell:cell interactions.

6.
Cell Rep ; 22(4): 979-991, 2018 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-29386139

RESUMO

T lymphocyte cytotoxicity relies on a synaptic ring of lymphocyte function-associated antigen 1 (LFA-1), which permits polarized delivery of lytic granules. How LFA-1 organization is controlled by underlying actin cytoskeleton dynamics is poorly understood. Here, we explored the contribution of the actin cytoskeleton regulator WASP to the topography of LFA-1 using a combination of microscopy modalities. We uncover that the reduced cytotoxicity of Wiskott-Aldrich syndrome patient-derived CD8+ T lymphocytes lacking WASP is associated with reduced LFA-1 activation, unstable synapse, and delayed lethal hit. At the nanometric scale, WASP constrains high-affinity LFA-1 into dense nanoclusters located in actin meshwork interstices. At the cellular scale, WASP is required for the assembly of a radial belt composed of hundreds of LFA-1 nanoclusters and for lytic granule docking within this belt. Our study unravels the nanoscale topography of LFA-1 at the lytic synapse and identifies WASP as a molecule controlling individual LFA-1 cluster density and LFA-1 nanocluster belt integrity.

7.
J Allergy Clin Immunol ; 142(1): 219-234, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29248492

RESUMO

BACKGROUND: Wiskott-Aldrich syndrome (WAS), X-linked thrombocytopenia (XLT), and X-linked neutropenia, which are caused by WAS mutations affecting Wiskott-Aldrich syndrome protein (WASp) expression or activity, manifest in immunodeficiency, autoimmunity, genomic instability, and lymphoid and other cancers. WASp supports filamentous actin formation in the cytoplasm and gene transcription in the nucleus. Although the genetic basis for XLT/WAS has been clarified, the relationships between mutant forms of WASp and the diverse features of these disorders remain ill-defined. OBJECTIVE: We sought to define how dysfunctional gene transcription is causally linked to the degree of TH cell deficiency and genomic instability in the XLT/WAS clinical spectrum. METHODS: In human TH1- or TH2-skewing cell culture systems, cotranscriptional R-loops (RNA/DNA duplex and displaced single-stranded DNA) and DNA double-strand breaks (DSBs) were monitored in multiple samples from patients with XLT and WAS and in normal T cells depleted of WASp. RESULTS: WASp deficiency provokes increased R-loops and R-loop-mediated DSBs in TH1 cells relative to TH2 cells. Mechanistically, chromatin occupancy of serine 2-unphosphorylated RNA polymerase II is increased, and that of topoisomerase 1, an R-loop preventing factor, is decreased at R-loop-enriched regions of IFNG and TBX21 (TH1 genes) in TH1 cells. These aberrations accompany increased unspliced (intron-retained) and decreased spliced mRNA of IFNG and TBX21 but not IL13 (TH2 gene). Significantly, increased cellular load of R-loops and DSBs, which are normalized on RNaseH1-mediated suppression of ectopic R-loops, inversely correlates with disease severity scores. CONCLUSION: Transcriptional R-loop imbalance is a novel molecular defect causative in TH1 immunodeficiency and genomic instability in patients with WAS. The study proposes that cellular R-loop load could be used as a potential biomarker for monitoring symptom severity and prognostic outcome in the XLT-WAS clinical spectrum and could be targeted therapeutically.

10.
J Cell Sci ; 130(1): 97-103, 2017 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-27034137

RESUMO

Border cell migration during Drosophila oogenesis is a potent model to study collective cell migration, a process involved in development and metastasis. Border cell clusters adopt two main types of behaviour during migration: linear and rotational. However, the molecular mechanism controlling the switch from one to the other is unknown. Here, we demonstrate that non-muscle Myosin II (NMII, also known as Spaghetti squash) activity controls the linear-to-rotational switch. Furthermore, we show that the regulation of NMII takes place downstream of guidance receptor signalling and is critical to ensure efficient collective migration. This study thus provides new insight into the molecular mechanism coordinating the different cell behaviours in a migrating cluster.


Assuntos
Movimento Celular , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citologia , Drosophila melanogaster/metabolismo , Miosina Tipo II/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais , Animais , Receptores ErbB/metabolismo , Rotação , Imagem com Lapso de Tempo
11.
Nat Immunol ; 17(12): 1352-1360, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27776107

RESUMO

RASGRP1 is an important guanine nucleotide exchange factor and activator of the RAS-MAPK pathway following T cell antigen receptor (TCR) signaling. The consequences of RASGRP1 mutations in humans are unknown. In a patient with recurrent bacterial and viral infections, born to healthy consanguineous parents, we used homozygosity mapping and exome sequencing to identify a biallelic stop-gain variant in RASGRP1. This variant segregated perfectly with the disease and has not been reported in genetic databases. RASGRP1 deficiency was associated in T cells and B cells with decreased phosphorylation of the extracellular-signal-regulated serine kinase ERK, which was restored following expression of wild-type RASGRP1. RASGRP1 deficiency also resulted in defective proliferation, activation and motility of T cells and B cells. RASGRP1-deficient natural killer (NK) cells exhibited impaired cytotoxicity with defective granule convergence and actin accumulation. Interaction proteomics identified the dynein light chain DYNLL1 as interacting with RASGRP1, which links RASGRP1 to cytoskeletal dynamics. RASGRP1-deficient cells showed decreased activation of the GTPase RhoA. Treatment with lenalidomide increased RhoA activity and reversed the migration and activation defects of RASGRP1-deficient lymphocytes.


Assuntos
Actinas/metabolismo , Linfócitos B/imunologia , Citoesqueleto/metabolismo , Proteínas de Ligação a DNA/genética , Fatores de Troca do Nucleotídeo Guanina/genética , Síndromes de Imunodeficiência/genética , Células Matadoras Naturais/imunologia , Linfócitos T/imunologia , Adolescente , Inibidores da Angiogênese/farmacologia , Linfócitos B/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Proliferação de Células/genética , Criança , Citotoxicidade Imunológica/genética , Análise Mutacional de DNA , Dineínas/metabolismo , Feminino , Células HEK293 , Humanos , Switching de Imunoglobulina/genética , Síndromes de Imunodeficiência/tratamento farmacológico , Células Jurkat , Células Matadoras Naturais/efeitos dos fármacos , Lenalidomida , Masculino , Mutação/genética , Linhagem , RNA Interferente Pequeno/genética , Linfócitos T/efeitos dos fármacos , Talidomida/análogos & derivados , Talidomida/farmacologia
12.
Front Immunol ; 6: 586, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26635800

RESUMO

The actin cytoskeleton is composed of a dynamic filament meshwork that builds the architecture of the cell to sustain its fundamental properties. This physical structure is characterized by a continuous remodeling, which allows cells to accomplish complex motility steps such as directed migration, crossing of biological barriers, and interaction with other cells. T lymphocytes excel in these motility steps to ensure their immune surveillance duties. In particular, actin cytoskeleton remodeling is a key to facilitate the journey of T lymphocytes through distinct tissue environments and to tune their stop and go behavior during the scanning of antigen-presenting cells. The molecular mechanisms controlling actin cytoskeleton remodeling during T lymphocyte motility have been only partially unraveled, since the function of many actin regulators has not yet been assessed in these cells. Our review aims to integrate the current knowledge into a comprehensive picture of how the actin cytoskeleton drives T lymphocyte migration. We will present the molecular actors that control actin cytoskeleton remodeling, as well as their role in the different T lymphocyte motile steps. We will also highlight which challenges remain to be addressed experimentally and which approaches appear promising to tackle them.

13.
Blood ; 126(16): 1911-20, 2015 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-26272216

RESUMO

Follicular lymphoma (FL) results from the accumulation of malignant germinal center (GC) B cells leading to the development of an indolent and largely incurable disease. FL cells remain highly dependent on B-cell receptor (BCR) signaling and on a specific cell microenvironment, including T cells, macrophages, and stromal cells. Importantly, FL BCR is characterized by a selective pressure to retain surface immunoglobulin M (IgM) BCR despite an active class-switch recombination process, and by the introduction, in BCR variable regions, of N-glycosylation acceptor sites harboring unusual high-mannose oligosaccharides. However, the relevance of these 2 FL BCR features for lymphomagenesis remains unclear. In this study, we demonstrated that IgM(+) FL B cells activated a stronger BCR signaling network than IgG(+) FL B cells and normal GC B cells. BCR expression level and phosphatase activity could both contribute to such heterogeneity. Moreover, we underlined that a subset of IgM(+) FL samples, displaying highly mannosylated BCR, efficiently bound dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), which could in turn trigger delayed but long-lasting BCR aggregation and activation. Interestingly, DC-SIGN was found within the FL cell niche in situ. Finally, M2 macrophages induced a DC-SIGN-dependent adhesion of highly mannosylated IgM(+) FL B cells and triggered BCR-associated kinase activation. Interestingly, pharmacologic BCR inhibitors abolished such crosstalk between macrophages and FL B cells. Altogether, our data support an important role for DC-SIGN-expressing infiltrating cells in the biology of FL and suggest that they could represent interesting therapeutic targets.


Assuntos
Moléculas de Adesão Celular/imunologia , Regulação da Expressão Gênica/imunologia , Imunoglobulina M/imunologia , Lectinas Tipo C/imunologia , Linfoma Folicular/imunologia , Macrófagos/imunologia , Receptores de Antígenos de Linfócitos B/imunologia , Receptores de Superfície Celular/imunologia , Transdução de Sinais/imunologia , Comunicação Celular/imunologia , Técnicas de Cocultura , Feminino , Glicosilação , Humanos , Linfoma Folicular/patologia , Macrófagos/patologia , Masculino , Células Tumorais Cultivadas
14.
Cell Rep ; 11(9): 1474-85, 2015 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-26027932

RESUMO

The killing of antigen-bearing cells by clonal populations of cytotoxic T lymphocytes (CTLs) is thought to be a rapid phenomenon executed uniformly by individual CTLs. We combined bulk and single-CTL killing assays over a prolonged time period to provide the killing statistics of clonal human CTLs against an excess of target cells. Our data reveal efficiency in sustained killing at the population level, which relied on a highly heterogeneous multiple killing performance at the individual level. Although intraclonal functional heterogeneity was a stable trait in clonal populations, it was reset in the progeny of individual CTLs. In-depth mathematical analysis of individual CTL killing data revealed a substantial proportion of high-rate killer CTLs with burst killing activity. Importantly, such activity was delayed and required activation with strong antigenic stimulation. Our study implies that functional heterogeneity allows CTL populations to calibrate prolonged cytotoxic activity to the size of target cell populations.


Assuntos
Citotoxicidade Imunológica/imunologia , Linfócitos T Citotóxicos/imunologia , Citometria de Fluxo , Humanos , Microscopia Confocal , Modelos Teóricos
15.
PLoS One ; 10(3): e0120053, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25815811

RESUMO

The dynamics of the interaction between Cytotoxic T Lymphocytes (CTL) and tumor cells has been addressed in depth, in particular using numerical simulations. However, stochastic mathematical models that take into account the competitive interaction between CTL and tumors undergoing immunoediting, a process of tumor cell escape from immunesurveillance, are presently missing. Here, we introduce a stochastic dynamical particle interaction model based on experimentally measured parameters that allows to describe CTL function during immunoediting. The model describes the competitive interaction between CTL and melanoma cell nodules and allows temporal and two-dimensional spatial progression. The model is designed to provide probabilistic estimates of tumor eradication through numerical simulations in which tunable parameters influencing CTL efficacy against a tumor nodule undergoing immunoediting are tested. Our model shows that the rate of CTL/tumor nodule productive collisions during the initial time of interaction determines the success of CTL in tumor eradication. It allows efficient cytotoxic function before the tumor cells acquire a substantial resistance to CTL attack, due to mutations stochastically occurring during cell division. Interestingly, a bias in CTL motility inducing a progressive attraction towards a few scout CTL, which have detected the nodule enhances early productive collisions and tumor eradication. Taken together, our results are compatible with a biased competition theory of CTL function in which CTL efficacy against a tumor nodule undergoing immunoediting is strongly dependent on guidance of CTL trajectories by scout siblings. They highlight unprecedented aspects of immune cell behavior that might inspire new CTL-based therapeutic strategies against tumors.


Assuntos
Melanoma/imunologia , Melanoma/patologia , Modelos Imunológicos , Linfócitos T Citotóxicos/metabolismo , Humanos , Modelos Biológicos , Monitorização Imunológica , Processos Estocásticos , Células Tumorais Cultivadas , Evasão Tumoral
16.
Front Immunol ; 6: 47, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25709608

RESUMO

Over the last decades, research dedicated to the molecular and cellular mechanisms underlying primary immunodeficiencies (PID) has helped to understand the etiology of many of these diseases and to develop novel therapeutic approaches. Beyond these aspects, PID are also studied because they offer invaluable natural genetic tools to dissect the human immune system. In this review, we highlight the research that has focused over the last 20 years on T lymphocytes from Wiskott-Aldrich syndrome (WAS) patients. WAS T lymphocytes are defective for the WAS protein (WASP), a regulator of actin cytoskeleton remodeling. Therefore, study of WAS T lymphocytes has helped to grasp that many steps of T lymphocyte activation and function depend on the crosstalk between membrane receptors and the actin cytoskeleton. These steps include motility, immunological synapse assembly, and signaling, as well as the implementation of helper, regulatory, or cytotoxic effector functions. The recent concept that WASP also works as a regulator of transcription within the nucleus is an illustration of the complexity of signal integration in T lymphocytes. Finally, this review will discuss how further study of WAS may contribute to solve novel challenges of T lymphocyte biology.

17.
Curr Biol ; 25(2): 242-250, 2015 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-25578904

RESUMO

Collective cell migration is a widespread biological phenomenon, whereby groups of highly coordinated, adherent cells move in a polarized fashion. This migration mode is a hallmark of tissue morphogenesis during development and repair and of solid tumor dissemination. In addition to circulating as solitary cells, lymphoid malignancies can assemble into tissues as multicellular aggregates. Whether malignant lymphocytes are capable of coordinating their motility in the context of chemokine gradients is, however, unknown. Here, we show that, upon exposure to CCL19 or CXCL12 gradients, malignant B and T lymphocytes assemble into clusters that migrate directionally and display a wider chemotactic sensitivity than individual cells. Physical modeling recapitulates cluster motility statistics and shows that intracluster cell cohesion results in noise reduction and enhanced directionality. Quantitative image analysis reveals that cluster migration runs are periodically interrupted by transitory rotation and random phases that favor leader cell turnover. Additionally, internalization of CCR7 in leader cells is accompanied by protrusion retraction, loss of polarity, and the ensuing replacement by new leader cells. These mechanisms ensure sustained forward migration and resistance to chemorepulsion, a behavior of individual cells exposed to steep CCL19 gradients that depends on CCR7 endocytosis. Thus, coordinated cluster dynamics confer distinct chemotactic properties, highlighting unexpected features of lymphoid cell migration.


Assuntos
Linfócitos B/citologia , Movimento Celular , Quimiocina CCL19/farmacologia , Quimiocina CXCL12/farmacologia , Quimiotaxia , Linfócitos T/citologia , Linfócitos B/efeitos dos fármacos , Linhagem Celular , Humanos , Linfócitos T/efeitos dos fármacos
18.
Cancer Res ; 73(11): 3412-24, 2013 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-23644527

RESUMO

Solid tumor dissemination relies on the reprogramming of molecular pathways controlling chemotaxis. Whether the motility of nonsolid tumors such as leukemia depends on the deregulated expression of molecules decoding chemotactic signals remains an open question. We identify here the membrane remodeling F-BAR adapter protein Cdc42-interacting protein 4 (CIP4) as a key regulator of chemotaxis in chronic lymphocytic leukemia (CLL). CIP4 is expressed at abnormally high levels in CLL cells, where it is required for CCL19-induced chemotaxis. Upon CCL19 stimulation of CLL cells, CIP4 associates with GTP-bound Cdc42 and is recruited to the rear of the lamellipodium and along microspikes radiating through the lamellipodium. Consistent with its cellular distribution, CIP4 removal impairs both the assembly of the polarized lamellipodium and directional migration along a diffusible CCL19 gradient. Furthermore, CIP4 depletion results in decreased activation of WASP, but increased activation of PAK1 and p38 mitogen-activated protein kinase (MAPK). Notably, p38 MAPK inhibition results in impaired lamellipodium assembly and loss of directional migration. This suggests that CIP4 modulates both the WASP and p38 MAPK pathways to promote lamellipodium assembly and chemotaxis. Overall, our study reveals a critical role of CIP4 in mediating chemotaxis of CLL cells by controlling the dynamics of microspike-containing protrusions and cell steering.


Assuntos
Quimiocina CCL19/metabolismo , Quimiocina CCL19/farmacologia , Quimiotaxia/efeitos dos fármacos , Leucemia Linfocítica Crônica de Células B/patologia , Proteínas Associadas aos Microtúbulos/metabolismo , Quimiocina CCL19/genética , Quimiotaxia/fisiologia , Técnicas de Silenciamento de Genes , Humanos , Leucemia Linfocítica Crônica de Células B/sangue , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/metabolismo , Microscopia Confocal , Proteínas Associadas aos Microtúbulos/deficiência , Proteínas Associadas aos Microtúbulos/genética , Antígenos de Histocompatibilidade Menor , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Pseudópodes/genética , Pseudópodes/metabolismo , Pseudópodes/patologia , Proteína da Síndrome de Wiskott-Aldrich/metabolismo , Proteína cdc42 de Ligação ao GTP/metabolismo
19.
Proc Natl Acad Sci U S A ; 110(15): 6073-8, 2013 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-23536289

RESUMO

It is presently assumed that lethal hit delivery by cytotoxic T lymphocytes (CTLs) is mechanistically linked to centrosome polarization toward target cells, leading to dedicated release of lytic granules within a confined secretory domain. Here we provide three lines of evidence showing that this mechanism might not apply as a general paradigm for lethal hit delivery. First, in CTLs stimulated with immobilized peptide-MHC complexes, lytic granules and microtubule organizing center localization into synaptic areas are spatio-temporally dissociated, as detected by total internal reflection fluorescence microscopy. Second, in many CTL/target cell conjugates, lytic granule secretion precedes microtubule polarization and can be detected during the first minute after cell-cell contact. Third, inhibition of microtubule organizing center and centrosome polarization impairs neither lytic granule release at the CTL synapse nor killing efficiency. Our results broaden current views of CTL biology by revealing an extremely rapid step of lytic granule secretion and by showing that microtubule organizing center polarization is dispensable for efficient lethal hit delivery.


Assuntos
Centrossomo/ultraestrutura , Sinapses Imunológicas , Microtúbulos/metabolismo , Vesículas Secretórias/metabolismo , Linfócitos T Citotóxicos/citologia , Polaridade Celular , Centrossomo/metabolismo , Grânulos Citoplasmáticos/metabolismo , Citotoxicidade Imunológica , Citometria de Fluxo , Humanos , Microscopia Confocal , Microscopia de Fluorescência , Centro Organizador dos Microtúbulos/ultraestrutura , Proteína Quinase C/metabolismo , Transdução de Sinais , Fatores de Tempo
20.
Eur J Cell Biol ; 91(11-12): 938-49, 2012 Nov-Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22999511

RESUMO

Leukocytes migrate through most tissues in the body, a process which takes place in 3D environments. We have previously shown that macrophages use the amoeboid migration mode in porous matrices such as fibrillar collagen I and the mesenchymal mode involving podosomes and matrix proteolysis in dense matrices such as Matrigel. Whether such a plasticity may apply to other leukocytes and to all subsets of macrophages is unknown. Here, we therefore provide a comparative analysis of the in vitro 3D migration modes adopted by primary human leukocytes. Blood-derived monocytes, neutrophils and T lymphocytes were found to use the amoeboid mode in a porous fibrillar collagen I matrix but were unable to infiltrate dense Matrigel and to form podosomes. M2-polarized macrophages and elicited peritoneal macrophages formed podosome rosettes, degraded the ECM and infiltrated both matrices. In contrast, M1 macrophages were motionless in 2D and 3D environments, whilst resident macrophages, devoid of podosomes, were only able to use the amoeboid mode. Thus, we conclude that whereas all leukocytes use the amoeboid mode to migrate through porous matrices, it is only certain macrophages that can adopt the mesenchymal mode that permits migration through dense matrices. Interestingly, the acquisition of mesenchymal migration capacity by macrophages correlates with the presence of podosomes and with their capacity to organize those as rosettes, which appears to be modulated by their differentiation and polarization states. As a perspective, specific control of the mesenchymal migration would be a potential target for therapeutic approaches aiming at decreasing macrophage tissue infiltration.


Assuntos
Movimento Celular , Extensões da Superfície Celular/fisiologia , Leucócitos/fisiologia , Leucócitos/ultraestrutura , Macrófagos/fisiologia , Macrófagos/ultraestrutura , Extensões da Superfície Celular/ultraestrutura , Colágeno , Colágeno Tipo I/química , Combinação de Medicamentos , Matriz Extracelular/química , Humanos , Laminina , Conformação Molecular , Fenótipo , Proteoglicanas
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