51
|
Abstract
Using an elaborately evolved language of cytokines and chemokines as well as cell-cell interactions, the different components of the immune system communicate with each other and orchestrate a response (or wind one down). Immunological synapses are a key feature of the system in the ways in which they can facilitate and direct these responses. Studies analyzing the structure of an immune synapse as it forms between two cells have provided insight into how the stability and kinetics of this interaction ultimately affect the sensitivity, potency, and magnitude of a given response. Furthermore, we have gained an appreciation of how the immunological synapse provides directionality and contextual cues for downstream signaling and cellular decision-making. In this review, we discuss how using a variety of techniques, developed over the last decade, have allowed us to visualize and quantify key aspects of the dynamic synaptic interface and have furthered our understanding of their function. We describe some of the many characteristics of the immunological synapse that make it a vital part of intercellular communication and some of the questions that remain to be answered.
Collapse
Affiliation(s)
- Jianming Xie
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Cristina M. Tato
- Institute for Immunity, Transplantation and Infection, Stanford University School of Medicine, Stanford, CA, USA
| | - Mark M. Davis
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
- Institute for Immunity, Transplantation and Infection, Stanford University School of Medicine, Stanford, CA, USA
- The Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA, USA
| |
Collapse
|
52
|
Chemin K, Bohineust A, Dogniaux S, Tourret M, Guégan S, Miro F, Hivroz C. Cytokine secretion by CD4+ T cells at the immunological synapse requires Cdc42-dependent local actin remodeling but not microtubule organizing center polarity. THE JOURNAL OF IMMUNOLOGY 2012; 189:2159-68. [PMID: 22821962 DOI: 10.4049/jimmunol.1200156] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Cytokine secretion by T lymphocytes plays a central role in mounting adaptive immune responses. However, little is known about how newly synthesized cytokines, once produced, are routed within T cells and about the mechanisms involved in regulating their secretions. In this study, we investigated the role of cytoskeleton remodeling at the immunological synapse (IS) in cytokine secretion. We show that a key regulator of cytoskeleton remodeling, the Rho GTPase Cdc42, controls IFN-γ secretion by primary human CD4+ T lymphocytes. Surprisingly, microtubule organizing center polarity at the IS, which does not depend on Cdc42, is not required for cytokine secretion by T lymphocytes, whereas microtubule polymerization is required. In contrast, actin remodeling at the IS, which depends on Cdc42, controls the formation of the polymerized actin ring at the IS, the dynamic concentration of IFN-γ-containing vesicles inside this ring, and the secretion of these vesicles. These results reveal a previously unidentified role of Cdc42-dependent actin remodeling in cytokine exocytosis at the IS.
Collapse
Affiliation(s)
- Karine Chemin
- Institut Curie, Centre de Recherche, Paris F-75248, France
| | | | | | | | | | | | | |
Collapse
|
53
|
The differential production of cytokines by human Langerhans cells and dermal CD14(+) DCs controls CTL priming. Blood 2012; 119:5742-9. [PMID: 22535664 DOI: 10.1182/blood-2011-08-371245] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We recently reported that human epidermal Langerhans cells (LCs) are more efficient than dermal CD14(+) DCs at priming naive CD8(+) T cells into potent CTLs. We hypothesized that distinctive dendritic cell (DC) cytokine expression profiles (ie, IL-15 produced by LCs and IL-10 expressed by dermal CD14(+) DCs) might explain the observed functional difference. Blocking IL-15 during CD8(+) T-cell priming reduced T-cell proliferation by ∼ 50%. These IL-15-deprived CD8(+) T cells did not acquire the phenotype of effector memory cells. They secreted less IL-2 and IFN-γ and expressed only low amounts of CD107a, granzymes and perforin, and reduced levels of the antiapoptotic protein Bcl-2. Confocal microscopy analysis showed that IL-15 is localized at the immunologic synapse of LCs and naive CD8(+) T cells. Conversely, blocking IL-10 during cocultures of dermal CD14(+) DCs and naive CD8(+) T cells enhanced the generation of effector CTLs, whereas addition of IL-10 to cultures of LCs and naive CD8(+) T cells inhibited their induction. TGF-β1 that is transcribed by dermal CD14(+) DCs further enhanced the inhibitory effect of IL-10. Thus, the respective production of IL-15 and IL-10 explains the contrasting effects of LCs and dermal CD14(+) DCs on CD8(+) T-cell priming.
Collapse
|
54
|
DOCK8 is a Cdc42 activator critical for interstitial dendritic cell migration during immune responses. Blood 2012; 119:4451-61. [PMID: 22461490 DOI: 10.1182/blood-2012-01-407098] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
To migrate efficiently through the interstitium, dendritic cells (DCs) constantly adapt their shape to the given structure of the extracellular matrix and follow the path of least resistance. It is known that this amoeboid migration of DCs requires Cdc42, yet the upstream regulators critical for localization and activation of Cdc42 remain to be determined. Mutations of DOCK8, a member of the atypical guanine nucleotide exchange factor family, causes combined immunodeficiency in humans. In the present study, we show that DOCK8 is a Cdc42-specific guanine nucleotide exchange factor that is critical for interstitial DC migration. By generating the knockout mice, we found that in the absence of DOCK8, DCs failed to accumulate in the lymph node parenchyma for T-cell priming. Although DOCK8-deficient DCs migrated normally on 2-dimensional surfaces, DOCK8 was required for DCs to crawl within 3-dimensional fibrillar networks and to transmigrate through the subcapsular sinus floor. This function of DOCK8 depended on the DHR-2 domain mediating Cdc42 activation. DOCK8 deficiency did not affect global Cdc42 activity. However, Cdc42 activation at the leading edge membrane was impaired in DOCK8-deficient DCs, resulting in a severe defect in amoeboid polarization and migration. Therefore, DOCK8 regulates interstitial DC migration by controlling Cdc42 activity spatially.
Collapse
|
55
|
Kohlhapp FJ, Zloza A, O'Sullivan JA, Moore TV, Lacek AT, Jagoda MC, McCracken J, Cole DJ, Guevara-Patiño JA. CD8(+) T cells sabotage their own memory potential through IFN-γ-dependent modification of the IL-12/IL-15 receptor α axis on dendritic cells. THE JOURNAL OF IMMUNOLOGY 2012; 188:3639-47. [PMID: 22430740 DOI: 10.4049/jimmunol.1101580] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD8(+) T cell responses have been shown to be regulated by dendritic cells (DCs) and CD4(+) T cells, leading to the tenet that CD8(+) T cells play a passive role in their own differentiation. In contrast, by using a DNA vaccination model, to separate the events of vaccination from those of CD8(+) T cell priming, we demonstrate that CD8(+) T cells, themselves, actively limit their own memory potential through CD8(+) T cell-derived IFN-γ-dependent modification of the IL-12/IL-15Rα axis on DCs. Such CD8(+) T cell-driven cytokine alterations result in increased T-bet and decreased Bcl-2 expression, and thus decreased memory progenitor formation. These results identify an unrecognized role for CD8(+) T cells in the regulation of their own effector differentiation fate and a previously uncharacterized relationship between the balance of inflammation and memory formation.
Collapse
Affiliation(s)
- Frederick J Kohlhapp
- Department of Surgery, Committee on Immunology, University of Chicago, Chicago, IL 60637, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
56
|
Compeer EB, Flinsenberg TWH, van der Grein SG, Boes M. Antigen processing and remodeling of the endosomal pathway: requirements for antigen cross-presentation. Front Immunol 2012; 3:37. [PMID: 22566920 PMCID: PMC3342355 DOI: 10.3389/fimmu.2012.00037] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 02/16/2012] [Indexed: 12/29/2022] Open
Abstract
Cross-presentation of endocytosed antigen as peptide/class I major histocompatibility complex complexes plays a central role in the elicitation of CD8+ T cell clones that mediate anti-viral and anti-tumor immune responses. While it has been clear that there are specific subsets of professional antigen presenting cells capable of antigen cross-presentation, identification of mechanisms involved is still ongoing. Especially amongst dendritic cells (DC), there are specialized subsets that are highly proficient at antigen cross-presentation. We here present a focused survey on the cell biological processes in the endosomal pathway that support antigen cross-presentation. This review highlights DC-intrinsic mechanisms that facilitate the cross-presentation of endocytosed antigen, including receptor-mediated uptake, maturation-induced endosomal sorting of membrane proteins, dynamic remodeling of endosomal structures and cell surface-directed endosomal trafficking. We will conclude with the description of pathogen-induced deviation of endosomal processing, and discuss how immune evasion strategies pertaining endosomal trafficking may preclude antigen cross-presentation.
Collapse
Affiliation(s)
- Ewoud Bernardus Compeer
- Department of Pediatric Immunology, University Medical Center Utrecht/Wilhelmina Children's Hospital Utrecht, Netherlands
| | | | | | | |
Collapse
|
57
|
Rougerie P, Delon J. Rho GTPases: masters of T lymphocyte migration and activation. Immunol Lett 2011; 142:1-13. [PMID: 22207038 DOI: 10.1016/j.imlet.2011.12.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 11/24/2011] [Accepted: 12/07/2011] [Indexed: 12/15/2022]
Abstract
Rho GTPases are key signal transducer elements activated in T cells by both chemokine and antigen receptors. These two signalling pathways control the two main functions of T lymphocytes: motility and activation. Rho GTPases are thus crucial for the development of an adequate immune response. In this review, we mostly focus on the roles of RhoA, Rac1 and Cdc42 in T cells. We show their importance in phenomena such as adhesion, morphological polarization, migration and antigen recognition.
Collapse
Affiliation(s)
- Pablo Rougerie
- Institut Cochin, Université Paris Descartes, Sorbonne Paris Cité, CNRS (UMR 8104), Paris, France; Inserm, U1016, Paris, France
| | | |
Collapse
|
58
|
Abstract
R-Ras is a member of the RAS superfamily of small GTP-binding proteins. The physiologic function of R-Ras has not been fully elucidated. We found that R-Ras is expressed by lymphoid and nonlymphoid tissues and drastically up-regulated when bone marrow progenitors are induced to differentiate into dendritic cells (DCs). To address the role of R-Ras in DC functions, we generated a R-Ras-deficient mouse strain. We found that tumors induced in Rras(-/-) mice formed with shorter latency and attained greater tumor volumes. This finding has prompted the investigation of a role for R-Ras in the immune system. Indeed, Rras(-/-) mice were impaired in their ability to prime allogeneic and antigen-specific T-cell responses. Rras(-/-) DCs expressed lower levels of surface MHC class II and CD86 in response to lipopolysaccharide compared with wild-type DCs. This was correlated with a reduced phosphorylation of p38 and Akt. Consistently, R-Ras-GTP level was increased within 10 minutes of lipopolysaccharide stimulation. Furthermore, Rras(-/-) DCs have attenuated capacity to spread on fibronectin and form stable immunologic synapses with T cells. Altogether, these findings provide the first demonstration of a role for R-Ras in cell-mediated immunity and further expand on the complexity of small G-protein signaling in DCs.
Collapse
|
59
|
Duchez S, Rodrigues M, Bertrand F, Valitutti S. Reciprocal Polarization of T and B Cells at the Immunological Synapse. THE JOURNAL OF IMMUNOLOGY 2011; 187:4571-80. [DOI: 10.4049/jimmunol.1100600] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
|
60
|
Buzz in the dendritic cell synapse. Blood 2011; 118:2381-2. [PMID: 21885607 DOI: 10.1182/blood-2011-07-364331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
|
61
|
Polarized Secretion of Lysosomes at the B Cell Synapse Couples Antigen Extraction to Processing and Presentation. Immunity 2011; 35:361-74. [DOI: 10.1016/j.immuni.2011.07.008] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 04/30/2011] [Accepted: 07/08/2011] [Indexed: 11/17/2022]
|
62
|
Nair P, Amsen D, Blander JM. Co-ordination of incoming and outgoing traffic in antigen-presenting cells by pattern recognition receptors and T cells. Traffic 2011; 12:1669-76. [PMID: 21762455 DOI: 10.1111/j.1600-0854.2011.01251.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dendritic cells are innate sentinels of the immune system and potent activators of naÏve T cells. Mechanisms must exist to enable these cells to achieve maximal activation of T cells specific for microbial antigens, while avoiding activation of T cells specific for self-antigens. Here we discuss how a combination of signals from pattern recognition receptors and T cells co-ordinates subcellular trafficking of antigen with both major histocompatibility complex class I and class II molecules and T-cell costimulatory molecules, resulting in the preferential presentation of microbial peptides within a stimulatory context.
Collapse
Affiliation(s)
- Priyanka Nair
- Department of Medicine, Immunology Institute, Mount Sinai School of Medicine, 1425 Madison Avenue, New York, NY 10029, USA
| | | | | |
Collapse
|
63
|
Cytoskeletal remodeling mediated by WASp in dendritic cells is necessary for normal immune synapse formation and T-cell priming. Blood 2011; 118:2492-501. [PMID: 21690559 DOI: 10.1182/blood-2011-03-340265] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Rearrangement of the cytoskeleton in T cells plays a critical role in the organization of a complex signaling interface referred to as immunologic synapse (IS). Surprisingly, the contribution of antigen presenting cells, in particular dendritic cells (DCs), to the structure and function of the IS has not been investigated in as much detail. We have used a natural model of cytoskeletal dysfunction caused by deficiency of the Wiskott-Aldrich syndrome protein (WASp) to explore the contribution of the DC cytoskeleton to IS formation and to T-cell priming. In an antigen-specific system, T-DC contacts were found to be less stable when DCs alone lacked WASp, and associated with multiple defects of IS structure. As a consequence, DCs were unable to support normal IL-12 secretion, and events downstream of TCR signaling were abrogated, including increased calcium flux, microtubule organizing center (MTOC) polarization, phosphorylation of ZAP-70, and T-cell proliferation. Formation of an effective signaling interface is therefore dependent on active cytoskeletal rearrangements in DCs even when T cells are functionally competent. Deficiency of DC-mediated activities may contribute significantly to the varied immunodysregulation observed in patients with WAS, and also in those with limited myeloid reconstitution after allogeneic hematopoietic stem cell transplantation.
Collapse
|
64
|
Cytokine release from innate immune cells: association with diverse membrane trafficking pathways. Blood 2011; 118:9-18. [PMID: 21562044 DOI: 10.1182/blood-2010-08-265892] [Citation(s) in RCA: 252] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Cytokines released from innate immune cells play key roles in the regulation of the immune response. These intercellular messengers are the source of soluble regulatory signals that initiate and constrain inflammatory responses to pathogens and injury. Although numerous studies describe detailed signaling pathways induced by cytokines and their specific receptors, there is little information on the mechanisms that control the release of cytokines from different cell types. Indeed, the pathways, molecules, and mechanisms of cytokine release remain a "black box" in immunology. Here, we review research findings and new approaches that have begun to generate information on cytokine trafficking and release by innate immune cells in response to inflammatory or infectious stimuli. Surprisingly complex machinery, multiple organelles, and specialized membrane domains exist in these cells to ensure the selective, temporal, and often polarized release of cytokines in innate immunity.
Collapse
|
65
|
Abstract
In this Perspective, we propose that communication theory--a field of mathematics concerned with the problems of signal transmission, reception and processing--provides a new quantitative lens for investigating multicellular biology, ancient and modern. What underpins the cohesive organisation and collective behaviour of multicellular ecosystems such as microbial colonies and communities (microbiomes) and multicellular organisms such as plants and animals, whether built of simple tissue layers (sponges) or of complex differentiated cells arranged in tissues and organs (members of the 35 or so phyla of the subkingdom Metazoa)? How do mammalian tissues and organs develop, maintain their architecture, become subverted in disease, and decline with age? How did single-celled organisms coalesce to produce many-celled forms that evolved and diversified into the varied multicellular organisms in existence today? Some answers can be found in the blueprints or recipes encoded in (epi)genomes, yet others lie in the generic physical properties of biological matter such as the ability of cell aggregates to attain a certain complexity in size, shape, and pattern. We suggest that Lasswell's maxim "Who says what to whom in what channel with what effect" provides a foundation for understanding not only the emergence and evolution of multicellularity, but also the assembly and sculpting of multicellular ecosystems and many-celled structures, whether of natural or human-engineered origin. We explore how the abstraction of communication theory as an organising principle for multicellular biology could be realised. We highlight the inherent ability of communication theory to be blind to molecular and/or genetic mechanisms. We describe selected applications that analyse the physics of communication and use energy efficiency as a central tenet. Whilst communication theory has and could contribute to understanding a myriad of problems in biology, investigations of multicellular biology could, in turn, lead to advances in communication theory, especially in the still immature field of network information theory.
Collapse
Affiliation(s)
- I S Mian
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | | |
Collapse
|
66
|
Abstract
CD4(+) T helper (T(H)) cells play a critical role in orchestrating a pleiotropy of immune activities against a large variety of pathogens. It is generally thought that this is achieved through the acquisition of highly specialized functions after activation followed by the differentiation into various functional subsets. The differentiation process of naive precursor T(H) cells into defined effector subsets is controlled by cells of the innate immune system and their complex array of effector molecules such as secreted cytokines and membrane bound costimulatory molecules. These provide a unique quantitative or qualitative signal initiating T(H) development, which is subsequently reinforced via T cell-mediated feedback signals and selective survival and proliferative cues, ultimately resulting in the predominance of a particular T cell subset. In recent years, the number of defined T(H)cell subsets has expanded and the once rigid division of labor among them has been blurred with reports of plasticity among the subsets. In this chapter, we summarize and speculate on the current knowledge of the differentiation requirements of T(H) cell lineages, with particular focus on the T(H)17 subset.
Collapse
|
67
|
Pulecio J, Petrovic J, Prete F, Chiaruttini G, Lennon-Dumenil AM, Desdouets C, Gasman S, Burrone OR, Benvenuti F. Cdc42-mediated MTOC polarization in dendritic cells controls targeted delivery of cytokines at the immune synapse. J Biophys Biochem Cytol 2010. [DOI: 10.1083/jcb1914oia10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
|