201
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Fallarino F, Orabona C, Vacca C, Bianchi R, Gizzi S, Asselin-Paturel C, Fioretti MC, Trinchieri G, Grohmann U, Puccetti P. Ligand and cytokine dependence of the immunosuppressive pathway of tryptophan catabolism in plasmacytoid dendritic cells. Int Immunol 2005; 17:1429-38. [PMID: 16172135 DOI: 10.1093/intimm/dxh321] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Murine plasmacytoid dendritic cells (pDCs) have been credited with a unique ability to express indoleamine 2,3-dioxygenase (IDO) function and mediate immunosuppression in specific settings; yet, the conditions of spontaneous versus induced activity have remained unclear. We have used maneuvers known to up-regulate IDO in different cell types and have examined the relative efficacy and mechanisms of the induced activity in splenic pDCs, namely, after specific receptor engagement by CTLA-4-Ig, CD200-Ig or CD28-Ig, the latter in combination with silenced expression of the suppressor of cytokine signaling 3 (SOCS3) gene. We found that pDCs (CD11c+ mPDCA-1+ 120G8+) do not express IDO and are not tolerogenic under basal conditions. B7-1 engagement by CTLA-4-Ig, CD200R1 engagement by CD200-Ig and B7-1/B7-2 engagement by CD28-Ig in SOCS3-deficient pDCs were each capable of initiating IDO-dependent tolerance via different mechanisms. IFN-gamma was the major cytokine responsible for CTLA-4-Ig effects, and type I IFNs for those of CD200-Ig. Immunosuppression by CD28-Ig in the absence of SOCS3 required IFN-gamma induction and IFN-like actions of IL-6. Therefore, although pDCs do not mediate IDO-dependent tolerance constitutively, multiple ligands and cytokines will contribute to the expression of a tolerogenic phenotype by pDCs in the mouse.
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Affiliation(s)
- Francesca Fallarino
- Department of Experimental Medicine, Section of Pharmacology, University of Perugia, 06126 Perugia, Italy
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202
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Abstract
The paradigm of tolerogenic/immature versus inflammatory/mature dendritic cells has dominated the recent literature regarding the role of these antigen-presenting cells in mediating immune homeostasis or self-tolerance and response to pathogens, respectively. This issue is further complicated by the identification of distinct subtypes of dendritic cells that exhibit different antigen-presenting cell effector functions. The discovery of pathogen-associated molecular patterns and toll-like receptors provides the mechanistic basis for dendritic cell recognition of specific pathogens and induction of appropriate innate and adaptive immune responses. Only recently has insight been gained into how dendritic cells contribute to establishing and/or maintaining immunological tolerance to self. Soluble and cellular mediators have been reported to effectively regulate the function of dendritic cells by inducing several outcomes ranging from non-inflammatory dendritic cells that lack the ability to induce T lymphocyte activation to dendritic cells that actively suppress T lymphocyte responses. A thorough discussion of these stimuli and their outcomes is essential to understanding the potential for modulating dendritic cell function in the treatment of inflammatory disease conditions.
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Affiliation(s)
- Mark A Wallet
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, CB7290, Chapel Hill, NC 27599, USA
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203
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Wong CK, Lun SWM, Ko FWS, Ip WK, Hui DSC, Lam CWK. Increased expression of plasma and cell surface co-stimulatory molecules CTLA-4, CD28 and CD86 in adult patients with allergic asthma. Clin Exp Immunol 2005; 141:122-9. [PMID: 15958078 PMCID: PMC1809415 DOI: 10.1111/j.1365-2249.2005.02815.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The co-stimulatory interactions of the B7 family molecules CD80 and CD86 on antigen-presenting cells, together with their T cell counter receptors CD28 and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), modulate T lymphocyte-mediated immune responses in a reciprocal manner. To investigate whether there is altered expression and the clinical significance of soluble co-stimulatory molecules in asthmatic patients, plasma concentrations of sCTLA-4, sCD28, sCD80 and sCD86 in 51 adult allergic asthmatic adults with or without steroid treatment, and 35 sex- and age-matched control subjects were measured by enzyme-linked immunosorbent assay (ELISA). Cell surface expression of CTLA-4 and CD28 on peripheral blood mononuclear cells (PBMC) were analysed by flow cytometry. Results showed that the plasma sCTLA-4 concentration was significantly higher in all asthmatic patients while sCD28 and sCD86 concentrations were significantly higher in steroid and non-steroid treated asthmatic patients, respectively, compared with control subjects (all P < 0.01). Significantly increased cell surface expression of CD28 but not CTLA-4 on PBMC was found in asthmatic patients compared with controls (P < 0.05). The plasma concentration and cell surface expression of CTLA-4 were found to exhibit positive and significant correlations with those of CD28 (both P < 0.05). Serum total IgE concentration correlated positively and significantly with sCTLA-4 and sCD28 concentrations in allergic asthmatic patients (both P < 0.05). The increased expression of these soluble co-stimulatory molecules may reflect the dysregulation of T cell activation, thereby contributing to the immunopathogenesis of allergic asthma.
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Affiliation(s)
- C K Wong
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong
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204
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Jansson A, Barnes E, Klenerman P, Harlén M, Sørensen P, Davis SJ, Nilsson P. A Theoretical Framework for Quantitative Analysis of the Molecular Basis of Costimulation. THE JOURNAL OF IMMUNOLOGY 2005; 175:1575-85. [PMID: 16034096 DOI: 10.4049/jimmunol.175.3.1575] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We present a theoretical framework for simulating the synaptic accumulation of the costimulatory molecules CD28, CTLA-4, B7-1, and B7-2, based on a system of mean-field, ordinary differential equations, and rigorous biophysical and expression data. The simulations show that binding affinity, stoichiometric properties, expression levels, and, in particular, competition effects all profoundly influence complex formation at cellular interfaces. B7-2 engages 33-fold more CD28 than CTLA-4 at the synapse in contrast to B7-1, which ligates approximately 7-fold more CTLA-4 than CD28. Although B7-1 completely dominates interactions with CTLA-4, forming linear arrays of 7-18 receptor-ligand pairs, CTLA-4 is fully engaged by B7-2 when B7-1 is absent. Additional simulations reveal the sensitivity of CD28 interactions to modeled transport processes. The results support the concept that B7-2 and B7-1 are the dominant ligands of CD28 and CTLA-4, respectively, and indicate that the inability of B7-2 to recruit CTLA-4 to the synapse cannot be due to the differential binding properties of B7-1 and B7-2 only. We discuss the apparent redundancy of B7-1 in the context of a potentially dynamic synaptic microenvironment, and in light of functions other than the direct enhancement of T cell inhibition by CTLA-4.
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MESH Headings
- Animals
- Antigen Presentation/immunology
- Antigens, CD/biosynthesis
- Antigens, CD/chemistry
- Antigens, CD/metabolism
- Antigens, Differentiation/biosynthesis
- Antigens, Differentiation/chemistry
- Antigens, Differentiation/metabolism
- B7-1 Antigen/biosynthesis
- B7-1 Antigen/chemistry
- B7-1 Antigen/metabolism
- B7-2 Antigen
- Biological Transport, Active/immunology
- CD28 Antigens/biosynthesis
- CD28 Antigens/chemistry
- CD28 Antigens/metabolism
- CTLA-4 Antigen
- Cell Communication/immunology
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Computer Simulation
- Dendritic Cells/chemistry
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Humans
- Ligands
- Lymphocyte Activation/immunology
- Membrane Glycoproteins/biosynthesis
- Membrane Glycoproteins/chemistry
- Membrane Glycoproteins/metabolism
- Models, Immunological
- Protein Binding/immunology
- Protein Interaction Mapping/methods
- Protein Transport/immunology
- T-Lymphocytes, Helper-Inducer/chemistry
- T-Lymphocytes, Helper-Inducer/immunology
- T-Lymphocytes, Helper-Inducer/metabolism
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Affiliation(s)
- Andreas Jansson
- Computational Biology, School of Life Sciences, University of Skövde, Skövde, Sweden
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205
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Abstract
Blockade of antigen nonspecific costimulatory signals is a promising approach for the treatment of autoimmune diseases including systemic lupus erythematosus (SLE). CTLA4Ig, an antagonist of the CD28/B7 costimulatory interaction, effectively prevents SLE onset in several murine models and, when used in combination with cyclophosphamide, can induce remission of active SLE nephritis. In this review we describe the known mechanisms of action of CTLA4Ig both in normal immunity and in autoimmune disease models and address issues about its activity that still need to be resolved. We discuss the preclinical use of CTLA4Ig in murine SLE models and the rationale for a clinical trial in SLE patients.
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Affiliation(s)
- A Davidson
- Department of Medicine, Columbia University, New York, NY, USA.
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206
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Vlad G, Cortesini R, Suciu-Foca N. License to heal: bidirectional interaction of antigen-specific regulatory T cells and tolerogenic APC. THE JOURNAL OF IMMUNOLOGY 2005; 174:5907-14. [PMID: 15879080 DOI: 10.4049/jimmunol.174.10.5907] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Naturally occurring CD4(+)CD25(+) regulatory T (T(R)) cells, a component of the innate immune response, which play a key role in the maintenance of self-tolerance, have become the focus of numerous studies over the last decade. These cells inhibit the immune response in an Ag-nonspecific manner, interacting with other T cells. Much less is known about adaptive T(R) cells, which develop in response to chronic antigenic stimulation, and act directly on professional and nonprofessional APC, rendering them tolerogenic and able to elicit the differentiation of CD8(+) and CD4(+) T cells with suppressive activity. In this review, we will discuss data pertaining to the bidirectional interaction between Ag-specific T(R) with APC and their clinical relevance.
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Affiliation(s)
- George Vlad
- Department of Pathology, Columbia University, New York, NY 10032, USA
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207
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Abstract
The B7 family consists of structurally related, cell-surface protein ligands, which bind to the CD28 family of receptors on lymphocytes and regulate immune responses via 'costimulatory' or 'coinhibitory' signals.
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Affiliation(s)
- Mary Collins
- Wyeth Research, 200 Cambridge Park Drive, Cambridge, MA 02140, USA.
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208
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Orabona C, Belladonna ML, Vacca C, Bianchi R, Fallarino F, Volpi C, Gizzi S, Fioretti MC, Grohmann U, Puccetti P. Cutting Edge: Silencing Suppressor of Cytokine Signaling 3 Expression in Dendritic Cells Turns CD28-Ig from Immune Adjuvant to Suppressant. THE JOURNAL OF IMMUNOLOGY 2005; 174:6582-6. [PMID: 15905495 DOI: 10.4049/jimmunol.174.11.6582] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
CTLA-4-Ig and CD28-Ig are both agonist ligands of B7 coreceptor molecules on mouse dendritic cells (DCs), yet they bias the downstream response in opposite directions, and CTLA-4-Ig promotes tolerance, whereas CD28-Ig favors the onset of immunity. Although B7 engagement by either ligand leads to a mixed cytokine response, a dominant IL-6 production in response to CD28-Ig prevents the IFN-gamma-driven induction of immunosuppressive tryptophan catabolism mediated by IDO. In the present study, we show that silencing the expression of suppressor of cytokine signaling 3 (SOCS3) in DCs by RNA interference renders CD28-Ig capable of activating IDO, likely as a result of unrestrained IFN-gamma signaling and IFN-gamma-like actions of IL-6. Thus, in the absence of SOCS3, CD28-Ig becomes immunosuppressive and mimics the action of CTLA-4-Ig on tryptophan catabolism.
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Affiliation(s)
- Ciriana Orabona
- Department of Experimental Medicine, University of Perugia, Italy
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209
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Tscharke DC, Suhrbier A. From mice to humans – murine intelligence for human CD8+T cell vaccine design. Expert Opin Biol Ther 2005; 5:263-71. [PMID: 15757387 DOI: 10.1517/14712598.5.2.263] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
There has been considerable progress in the design of vaccines capable of safely and effectively inducing CD8(+) T cells for prophylaxis and treatment of chronic infectious diseases and cancer. Much of what is known about CD8(+) T cell-mediated immunity has come from pioneering work in mice; this broad overview discusses recent work in mouse systems where lessons may be drawn for human vaccine development. The areas highlighted include antivector immunity, immunodominance, dendritic cell biology and targeting, the role of Toll-like receptors and their exploitation by novel adjuvants, the role of CD4(+) T cell help, regulatory T cells and, finally, some comments on the different requirements of prophylactic versus therapeutic vaccines.
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Affiliation(s)
- David C Tscharke
- Queensland Institute of Medical Research, EBVBiology, P.O. Royal Brisbane Hospital, Brisbane, QLD 4029, Australia.
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210
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Redmond WL, Sherman LA. Peripheral Tolerance of CD8 T Lymphocytes. Immunity 2005; 22:275-84. [PMID: 15780985 DOI: 10.1016/j.immuni.2005.01.010] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 01/10/2005] [Accepted: 01/13/2005] [Indexed: 01/18/2023]
Abstract
Whereas high-avidity recognition of peptide-MHC complexes by developing T cells in the thymus results in deletion and promotes self-tolerance, such recognition by mature T cells in the periphery results in activation and clonal expansion. This dichotomy represents the basis of a dilemma that has stumped immunologists for many years, how are self-specific T cells tolerized in the periphery? There appear to be two important criteria used to achieve this goal. The first is that in the absence of inflammatory pathogens, tolerance is promoted when T cells recognize antigen presented by quiescent dendritic cells (DCs) expressing low levels of costimulatory molecules. A second critical factor that defines "self" and drives tolerance through deletion, anergy, or suppression is the persistence of antigen.
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Affiliation(s)
- William L Redmond
- Department of Immunology, The Scripps Research Institute, La Jolla, California 92037, USA
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211
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Bozza S, Fallarino F, Pitzurra L, Zelante T, Montagnoli C, Bellocchio S, Mosci P, Vacca C, Puccetti P, Romani L. A Crucial Role for Tryptophan Catabolism at the Host/Candida albicansInterface. THE JOURNAL OF IMMUNOLOGY 2005; 174:2910-8. [PMID: 15728502 DOI: 10.4049/jimmunol.174.5.2910] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
By mediating tryptophan catabolism, the enzyme indoleamine 2,3-dioxygenase (IDO) has a complex role in immunoregulation in infection, pregnancy, autoimmunity, transplantation, and neoplasia. We hypothesized that IDO might affect the outcome of the infection in mice infected with Candida albicans by virtue of its potent regulatory effects on inflammatory and T cell responses. IDO expression was examined in mice challenged with the fungus along with the consequences of its blockade by in vivo treatment with an enzyme inhibitor. We found that IDO activity was induced at sites of infection as well as in dendritic cells and effector neutrophils via IFN-gamma- and CTLA-4-dependent mechanisms. IDO inhibition greatly exacerbated infection and associated inflammatory pathology as a result of deregulated innate and adaptive/regulatory immune responses. However, a role for tryptophan catabolism was also demonstrated in a fungus-autonomous fashion; its blockade in vitro promoted yeast-to-hyphal transition. These results provide novel mechanistic insights into complex events that, occurring at the fungus/pathogen interface, relate to the dynamics of host adaptation to the fungus. The production of IFN-gamma may be squarely placed at this interface, where IDO activation probably exerts a fine control over fungal morphology as well as inflammatory and adaptive antifungal responses.
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Affiliation(s)
- Silvia Bozza
- Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy
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212
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