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Yusuf-Makagiansar H, Yakovleva TV, Tejo BA, Jones K, Hu Y, Verkhivker GM, Audus KL, Siahaan TJ. Sequence recognition of alpha-LFA-1-derived peptides by ICAM-1 cell receptors: inhibitors of T-cell adhesion. Chem Biol Drug Des 2007; 70:237-46. [PMID: 17718718 DOI: 10.1111/j.1747-0285.2007.00549.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Blocking the T-cell adhesion signal from intercellular adhesion molecule-1/leukocyte function-associated antigen-1 interactions (Signal-2) can suppress the progression of autoimmune diseases (i.e. type-1 diabetes, psoriasis) and prevent allograph rejection. In this study, we determined the active region(s) of cLAB.L peptide [cyclo(1,12)Pen-ITDGEATDSGC] by synthesizing and evaluating the biologic activity of hexapeptides in inhibiting T-cell adhesion. A new heterotypic T-cell adhesion assay was also developed to provide a model for the T-cell adhesion process during lung inflammation. Two hexapeptides, ITDGEA and DGEATD, were found to be more active than the other linear hexapeptides. The cyclic derivative of ITDGEA [i.e. cyclo(1,6)ITDGEA] has similar activity than the parent linear peptide and has lower activity than cLAB.L peptide. Computational-binding experiments were carried out to explain the possible mechanism of binding of these peptides to intercellular adhesion molecule-1. Both ITDGEA and DGEATD bind the same site on intercellular adhesion molecule-1 and they interact with the Gln34 and Gln73 residues on D1 of intercellular adhesion molecule-1. In the future, more potent derivatives of cyclo(1,6)ITDGEA will be designed by utilizing structural and binding studies of the peptide to intercellular adhesion molecule-1. The heterotypic T-cell adhesion to Calu-3 will also be used as another assay to evaluate the selectivity of the designed peptides.
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Katzav S. Flesh and blood: The story of Vav1, a gene that signals in hematopoietic cells but can be transforming in human malignancies. Cancer Lett 2007; 255:241-54. [PMID: 17590270 DOI: 10.1016/j.canlet.2007.04.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 04/30/2007] [Accepted: 04/30/2007] [Indexed: 01/08/2023]
Abstract
Cancer results from the interaction of multiple aberrations including activation of dominant oncogenes and upregulation of signal transduction pathways. Identification of the genes involved in malignant transformation is a pre-requisite for understanding cancer and improving its diagnosis and treatment. Quite a few of the genes that have been implicated in cancer are mutant or aberrantly expressed versions of genes that are important mediators of the normal growth that occurs during development. An important example of this is Vav1, a cytoplasmic signal transducer protein initially identified as an oncogene. Physiological expression of Vav1 is restricted to the hematopoietic system, where its best-known function is as a GDP/GTP nucleotide exchange factor for Rho/Rac GTPases, an activity strictly controlled by tyrosine phosphorylation. Vav1 was shown to regulate cytoskeletal rearrangement during activation of hematopoietic cells. Vav1 can also mediate other cellular functions including activation of the JNK, ERK, Ras, NF-kB, and NFAT pathways, in addition to association with numerous adapter proteins such as Shc, NCK, SLP-76, GRB2, and Crk. Although the oncogenic form of Vav1 has not been detected in clinical human tumors, its wild-type form has recently been implicated in mammalian malignancies such as neuroblastoma, melanoma, pancreatic tumors and B-cell chronic lymphocytic leukemia. This review addresses the physiological function of wild-type Vav1, its mode of activation as an oncogene, and its emerging role as a transforming protein in human cancer.
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Affiliation(s)
- Shulamit Katzav
- The Hubert H. Humphrey center for Experimental Medicine & Cancer Research, The Hebrew University-Hadassah Medical School, P.O. Box 12272, Jerusalem 91120, Israel.
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53
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Weber MS, Steinman L, Zamvil SS. Statins--treatment option for central nervous system autoimmune disease? Neurotherapeutics 2007; 4:693-700. [PMID: 17920550 PMCID: PMC7479672 DOI: 10.1016/j.nurt.2007.08.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Statins, inhibitors of the enzyme 3-hydroxy-3-methylglutaryl coenzyme A reductase, are well-established agents to lower cholesterol levels and prevent cardiovascular morbidity. Independent of their lipid-lowering properties, statins have been shown to exert pleiotropic immunomodulatory effects in various animal models of human autoimmune disease. In experimental autoimmune encephalomyelitis, a murine model for multiple sclerosis, statins prevented disease onset and even reversed paralysis when treatment was initiated after experimental autoimmune encephalomyelitis was fully established. Furthermore, well-tolerated oral statins were recently shown to exert synergistic benefit in experimental autoimmune encephalomyelitis in combination with existing agents for multiple sclerosis therapy. Based primarily on these encouraging results, statins are now being tested in clinical trials as a monotherapy for multiple sclerosis, as well as in combination with approved disease-modifying therapies.
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Affiliation(s)
- Martin S. Weber
- Department of Neurology, Program in Immunology, University of California, San Francisco, 513 Parnassus Avenue, S-268, 94143 San Francisco, CA
| | - Lawrence Steinman
- Department of Neurology and Neurological Sciences and Interdepartmental Program in Immunology, Stanford University, 94305 Stanford, California
| | - Scott S. Zamvil
- Department of Neurology, Program in Immunology, University of California, San Francisco, 513 Parnassus Avenue, S-268, 94143 San Francisco, CA
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54
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Grayson MH, Holtzman MJ. Emerging role of dendritic cells in respiratory viral infection. J Mol Med (Berl) 2007; 85:1057-68. [PMID: 17891367 DOI: 10.1007/s00109-007-0212-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 03/30/2007] [Accepted: 04/24/2007] [Indexed: 10/23/2022]
Abstract
Respiratory viral infections are a major health problem, especially in the immunocompromised, young, and elderly. In order for the host to effectively clear viral infections, a productive adaptive immune response must be developed. Crucial to the initiation of the adaptive response is the dendritic cell, which induces the proliferation and activation of T cells early in an antiviral response. This review examines the role of lung dendritic cells in the immune response to respiratory viruses. The phenotypic and functional differences between conventional and plasmacytoid dendritic cells are discussed, as are the mechanisms behind homeostatic recruitment of these cells in the normal lung. Focusing on respiratory syncytial virus and influenza, the role of the two dendritic cell subsets during an antiviral response is explored. Through evolution, viruses have developed several mechanisms to interfere with the normal function of dendritic cells and prevent appropriate induction of an adaptive immune response, which are also discussed. Finally, we identify potential targets for future therapeutic strategies to ameliorate disease caused by respiratory virus infection.
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Affiliation(s)
- Mitchell H Grayson
- Department of Internal Medicine, Washington University School of Medicine, Campus Box 8122, 660 South Euclid Avenue, Saint Louis, MO 63110, USA.
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55
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Abstract
We review recent advances toward a comprehensive mathematical theory of T-cell immunity. A key insight is that the efficacy of the T-cell response is best analyzed in terms of T-cell receptor (TCR) avidity and the distribution of this avidity across the TCR repertoire (the 'avidity spectrum'). Modification of this avidity spectrum by a wide range of tuning and tolerance mechanisms allows the system to adapt cross-reactivity and specificity to the challenge at hand while avoiding inappropriate responses against non-pathogenic cells and tissues. Theoretical models relate molecular kinetic parameters and cellular properties to systemic level statistics such as avidity spectra. Such bridge equations are crucial for rational clinical manipulation of T cells at the molecular level.
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Affiliation(s)
- Hugo A van den Berg
- Warwick Systems Biology Centre, Mathematics Institute, University of Warwick, Coventry, UK.
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56
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Jackman RP, Balamuth F, Bottomly K. CTLA-4 Differentially Regulates the Immunological Synapse in CD4 T Cell Subsets. THE JOURNAL OF IMMUNOLOGY 2007; 178:5543-51. [PMID: 17442936 DOI: 10.4049/jimmunol.178.9.5543] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Primary murine Th1 and Th2 cells differ in the organization of the immunological synapse, with Th1 cells, but not Th2 cells, clustering signaling molecules at the T cell/B cell synapse site. We sought to determine whether differential costimulatory signals could account for the differences observed. We found that Th2 cells express higher levels of CTLA-4 than Th1 cells, and demonstrated that Th2 cells lacking CTLA-4 are now able to cluster the TCR with the same frequency as Th1 cells. Furthermore, reconstitution of CTLA-4 into CTLA-4-deficient Th2 cells, or into Th1 cells, inhibits the clustering of the TCR. We have also shown that Th2 cells, but not Th1 cells, show variations in the organization of the immunological synapse depending on levels of expression of CD80/CD86 on the APC. These studies demonstrate a unique role for CTLA-4 as a critical regulator of Th2 cells and the immunological synapse.
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Affiliation(s)
- Rachael P Jackman
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520, USA.
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57
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Dar WA, Knechtle SJ. CXCR3-mediated T-cell chemotaxis involves ZAP-70 and is regulated by signalling through the T-cell receptor. Immunology 2007; 120:467-85. [PMID: 17250586 PMCID: PMC2265907 DOI: 10.1111/j.1365-2567.2006.02534.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The chemokine receptor CXCR3 is critical for the function of activated T cells. We studied the molecular mechanisms of CXCR3 signalling. The addition of CXCR3 ligands to normal human T cells expressing CXCR3 led to the tyrosine phosphorylation of multiple proteins. Addition of the same ligands to Jurkat T cells engineered to express CXCR3 induced tyrosine phosphorylation of proteins with molecular weights similar to those in normal cells. Immunoblotting with phosphotyrosine-specific antibodies identified Zeta-associated protein of 70,000 molecular weight (ZAP-70), linker for the activation of T cells (LAT), and phospholipase-C-gamma1 (PLCgamma1) to be among the proteins that become phosphorylated upon CXCR3 activation. ZAP-70 was phosphorylated on tyrosine 319, LAT on tyrosines 171 and 191, and PLCgamma1 on tyrosine 783. The ZAP-70 inhibitor piceatannol reduced CXCR3-mediated tyrosine phosphorylation of ZAP-70, LAT, PLCgamma1 and mitogen-activated protein kinase Erk and it reduced CXCL10-mediated chemotaxis of both CXCR3-transfected Jurkat T cells and normal T cells expressing CXCR3. These results are consistent with the involvement of ZAP-70 in CXCR3-mediated protein tyrosine phosphorylation and CXCR3-induced T-cell chemotaxis. Studies with the Lck-deficient Jurkat T-cell line, JCAM1.6, demonstrated that phosphorylation of ZAP-70 after CXCR3 activation is a Lck-dependent process. Finally, stimulating CXCR3-expressing Jurkat T cells and normal T cells expressing CXCR3 through the T-cell receptor attenuated CXCR3-induced tyrosine phosphorylation and CXCR3-mediated T-cell migration, indicating the occurrence of cross-talk between T-cell receptor and CXCR3-signalling pathways. These results shed light on the mechanisms of CXCR3 signalling. Such information could be useful when designing therapeutic strategies to regulate T-cell function.
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Affiliation(s)
- Wasim A Dar
- Department of Surgery, Division of Transplantation, University of Wisconsin-Madison, Madison, WI 53792-7375, USA.
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58
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59
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Tavano R, Contento RL, Baranda SJ, Soligo M, Tuosto L, Manes S, Viola A. CD28 interaction with filamin-A controls lipid raft accumulation at the T-cell immunological synapse. Nat Cell Biol 2006; 8:1270-6. [PMID: 17060905 DOI: 10.1038/ncb1492] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Accepted: 09/22/2006] [Indexed: 12/13/2022]
Abstract
During physiological T-cell stimulation by antigen presenting cells (APCs), a major T-cell membrane rearrangement is known to occur leading to the organization of 'supramolecular activation clusters' at the immunological synapse. A possible role for the synapse is the generation of membrane compartments where signalling may be organized and propagated. Thus, engagement of the costimulatory molecule CD28 at the immunological synapse promotes the organization of a signalling compartment by inducing cytoskeletal changes and lipid raft accumulation. We identified the actin-binding protein Filamin-A (FLNa) as a novel molecular partner of CD28. We found that, after physiological stimulation, CD28 associated with and recruited FLNa into the immunological synapse, where FLNa organized CD28 signalling. FLNa knockdown by short interfering RNA (siRNA) inhibited CD28-mediated raft accumulation at the immunological synapse and T-cell costimulation. Together, our data indicate that CD28 binding to FLNa is required to induce the T-cell cytoskeletal rearrangements leading to recruitment of lipid microdomains and signalling mediators into the immunological synapse.
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Affiliation(s)
- Regina Tavano
- Venetian Institute of Molecular Medicine, Department of Biomedical Science, University of Padua, 35100 Padua, Italy
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60
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Weber MS, Youssef S, Dunn SE, Prod'homme T, Neuhaus O, Stuve O, Greenwood J, Steinman L, Zamvil SS. Statins in the treatment of central nervous system autoimmune disease. J Neuroimmunol 2006; 178:140-8. [PMID: 16860400 DOI: 10.1016/j.jneuroim.2006.06.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2006] [Revised: 05/26/2006] [Accepted: 06/01/2006] [Indexed: 11/30/2022]
Abstract
Statins, inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase, are widely prescribed for their cholesterol-lowering properties to reduce atherogenesis and cardiovascular morbidity. Over recent years, statins have also been shown to exert pleiotropic immunomodulatory effects that might be of therapeutic benefit in autoimmune disorders. The primary mechanism by which statins alter immune function appears to be mediated through the inhibition of post-translational protein prenylation of small GTP-binding proteins and is largely independent of lipid-lowering. In experimental autoimmune encephalomyelitis (EAE), the mouse model for multiple sclerosis (MS), statins prevent or reverse paralysis and were recently shown to exert synergistic benefit when combined with agents approved for MS therapy. Based primarily upon the beneficial effects in EAE, statins are now being tested in patients in MS clinical trials.
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Affiliation(s)
- Martin S Weber
- Department of Neurology and Program in Immunology, University of California, San Francisco, USA
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61
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Anderson ME, Tejo BA, Yakovleva T, Siahaan TJ. Characterization of Binding Properties of ICAM-1 Peptides to LFA-1: Inhibitors of T-cell Adhesion. Chem Biol Drug Des 2006; 68:20-8. [PMID: 16923022 DOI: 10.1111/j.1747-0285.2006.00407.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present study, we characterized the binding site of two intercellular adhesion molecule-1-derived cyclic peptides, cIBC and cIBR, to the LFA-1 on the surface of T cells. These peptides had been able to inhibit LFA-1/intercellular adhesion molecule-1 signal by blocking the signal-2 of immune synapse. Both peptides prefer to bind to the closed form of LFA-1 I-domain, indicating that two peptides act as allosteric inhibitors against intercellular adhesion molecule-1. Binding site mapping using monoclonal antibodies proposes that cIBC binds to around residues 266-272 of LFA-1 I-domain where this site is adjacent to the metal ion-dependent adhesion site. On the other hand, cIBR binds to the pocket called L-site where is distant from metal ion-dependent adhesion site. Cross-inhibition mapping between two peptides show that cIBR could inhibit the binding of cIBC but not vice versa, suggesting that cIBR has some properties that allow this peptide bind to more than one site. Structural comparison between cIBC and cIBR reveals that cIBR is more flexible than cIBC, allowing this peptide bind to exposed region, such as cIBC-binding site as well as cramped pocket like L-site. Our findings are important for understanding the selectivity of cIBC and cIBR peptides; thus, they can be conjugated with drugs and transported specifically to the target.
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Affiliation(s)
- Meagan E Anderson
- Department of Pharmaceutical Chemistry, The University of Kansas, 2095 Constant Ave, Lawrence, KS 66047, USA
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62
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Grayson MH. Lung dendritic cells and the inflammatory response. Ann Allergy Asthma Immunol 2006; 96:643-51; quiz 652-3, 678. [PMID: 16729776 DOI: 10.1016/s1081-1206(10)61061-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE To discuss the role of conventional and plasmacytoid dendritic cells in inducing and modulating immune responses in the lung. DATA SOURCES The primary literature and selected review articles studying the role of dendritic cells in both rodent and human lungs as identified via a PubMed/MEDLINE search using the keywords dendritic cell, antigen-presenting cell, viral airway disease, asthma, allergy, and atopy. STUDY SELECTION The author's knowledge of the field was used to identify studies that were relevant to the stated objective. RESULTS Dendritic cells are well positioned in the respiratory tract and other mucosal surfaces to respond to any foreign protein. These cells are crucial to the initiation of the adaptive immune response through induction of antigen specific T-cell responses. These cells also play an important role in the regulation of developing and ongoing immune responses, an area that is currently under intense investigation. This review discusses the various subsets of human and rodent dendritic cells and the pathways involved in antigen processing and subsequent immune regulation by dendritic cells in the lung using both viral and nonviral allergenic protein exposure as examples. CONCLUSIONS Conventional and plasmacytoid dendritic cells are uniquely situated in the immune cascade to not only initiate but also modulate immune responses. Therapeutic interventions in allergic and asthmatic diseases will likely be developed to take advantage of this exclusive position of the dendritic cell.
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Affiliation(s)
- Mitchell H Grayson
- Division of Allergy and Immunology, Department of Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, USA.
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63
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Yang H, Reinherz EL. CD2BP1 modulates CD2-dependent T cell activation via linkage to protein tyrosine phosphatase (PTP)-PEST. THE JOURNAL OF IMMUNOLOGY 2006; 176:5898-907. [PMID: 16670297 DOI: 10.4049/jimmunol.176.10.5898] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Human CD2 regulates T cell activation and adhesion via mechanisms yet to be fully understood. This study focuses on CD2BP1, a CD2 cytoplasmic tail-binding protein preferentially expressed in hematopoetic cells. Structural and functional analyses suggest that CD2BP1 acts as a scaffold protein, participating in regulation of the actin cytoskeleton. In this study, using a murine Ag-specific primary T cell transduction system to assess CD69, IL-2, and IFN-gamma expression, we provide evidence that CD2BP1 directly and negatively impacts T cell activation via isolated CD2 triggering or TCR stimulation dependent on coordinate CD2 engagement. Disruption of protein tyrosine phosphatase-PEST and/or CD2BP1 association with the CD2 signalsome rescues T cells from the inhibitory effect of CD2 crosslinking. The overexpression of CD2BP1 selectively attenuates phospholipase Cgamma1, ERK1/2, and p38 phosphorylation without abrogating CD2-independent TCR stimulation. This study provides new insight on the regulation of T cell activation and may have implications for autoimmune processes known to be associated with CD2BP1 mutations.
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Affiliation(s)
- Hailin Yang
- Laboratory of Immunobiology, Department of Medical Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA
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Dustin ML, Tseng SY, Varma R, Campi G. T cell-dendritic cell immunological synapses. Curr Opin Immunol 2006; 18:512-6. [PMID: 16777399 DOI: 10.1016/j.coi.2006.05.017] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2006] [Accepted: 05/31/2006] [Indexed: 11/24/2022]
Abstract
Dendritic cells (DCs) are myeloid lineage cells that are imprinted by their environment and that mature in response to microbial products. A crucial role of the DC is to impart this context-specific information to T cells as well as to present self and foreign MHC-peptide complexes through formation of an immunological synapse. The structure of the T cell-DC immunological synapse departs from the canonical structure formed with B cells or with supported planar bilayers in that it has multiple foci of T-cell receptor interactions rather than a central focus. Recent studies on model systems provide insight into the mechanisms and biological consequences of the unique T cell-DC synaptic patterns.
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Affiliation(s)
- Michael L Dustin
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine and Department of Pathology, New York University School of Medicine, NY 10016, USA
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65
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Redecker P, Bockmann J, Böckers TM. Expression of postsynaptic density proteins of the ProSAP/Shank family in the thymus. Histochem Cell Biol 2006; 126:679-85. [PMID: 16758162 DOI: 10.1007/s00418-006-0199-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2006] [Indexed: 10/24/2022]
Abstract
PSD95-DLG-ZO1 domain-containing proteins of the ProSAP/Shank family are major scaffolding proteins of the neuronal postsynaptic density which play a pivotal role in the linkage of membrane receptors to downstream signal effectors and the actin-based cytoskeleton. Recently, ProSAP1/Shank2 has also been localized in various non-neuronal cells where it may fulfill similar functions as in neurons. We now complement these data by the study of ProSAP/Shank expression at the mRNA and protein level in a primary lymphoid organ, i.e., the thymus. Transcripts for ProSAP1/Shank2, the spliceoform Shank2E, and ProSAP2/Shank3 could be clearly detected in the thymus. Western blot and immunocytochemical analyses verified the presence of ProSAP1/Shank2 and ProSAP2/Shank3 proteins in thymic tissue. Immunoreactivity was concentrated in the whole peripheral cytoplasm of thymocytes underneath the plasma membrane. Discrete subplasmalemmal areas of pronounced ProSAP/Shank immunoreactivity could be demonstrated inside several thymocytes by confocal laser scanning microscopy. Our results establish ProSAP/Shank as a constituent of the cell cortex of thymocytes and thus lead to the hypothesis that ProSAP/Shank proteins serve as a platform for the coordination of membrane receptor-dependent signal transduction in immune cells.
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Affiliation(s)
- Peter Redecker
- Department of Cell Biology, Center of Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
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66
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Sato T, Habtezion A, Beilhack A, Schulz S, Butcher E, Thorlacius H. Short-term homing assay reveals a critical role for lymphocyte function-associated antigen-1 in the hepatic recruitment of lymphocytes in graft-versus-host disease. J Hepatol 2006; 44:1132-40. [PMID: 16466827 DOI: 10.1016/j.jhep.2005.11.042] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 10/20/2005] [Accepted: 11/03/2005] [Indexed: 12/04/2022]
Abstract
BACKGROUND/AIMS The liver is a major target organ of graft versus host disease (GvHD) with massive infiltration of alloreactive lymphocytes resulting in hepatitis and hepatocyte injury. Although adhesive mechanisms have been implicated in the biology of GvHD hepatitis, the identity of homing receptors involved in the initial recruitment of cells from the blood is not known. METHODS We have developed a short-term homing assay in a model of murine GvHD. Splenocytes from donors at an active stage of GvHD were injected intravenously into adoptive recipients also undergoing GvHD. The recruitment of cells to the liver was assessed 6h after cell transfer. RESULTS Activated donor CD8 and CD4 lymphocytes expressed lymphocyte function antigen-1 (LFA-1), alpha4-integrins, and P-selectin binding ligands, and localized more efficiently than naïve T cells. Immunoneutralization of LFA-1 reduced the recruitment of CD8 and CD4 lymphocytes to the liver by more than 60%. Anti-LFA-1 antibody also markedly reduced infiltration of lymphocytes in periportal areas and protected against hepatocellular damage. CONCLUSIONS We demonstrate a critical role of LFA-1 in the recruitment of activated lymphocytes to the liver and in immune-cell mediated hepatitis. LFA-1 may be an effective therapeutic target for protecting the liver following bone marrow transplantation.
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Affiliation(s)
- Tohru Sato
- Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, and the Center for Molecular Biology and Medicine, Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, USA.
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Abstract
Functional polarization of leukocytes is a requisite to accomplish immune function. Immune synapse formation or chemotaxis requires asymmetric redistribution of membrane receptors, signaling molecules and the actin cytoskeleton. There is increasing evidence that compartmentalization of the plasma membrane into distinct lipid microdomains is pivotal in establishing and maintaining leukocyte polarity. Specific rafts assemble into large-scale domains to create plasma membrane asymmetries at specific cell locations, thus coordinating temporally and spatially cell signaling in these processes. In this review we discuss the roles of lipid rafts as organizers of T lymphocyte polarity during cell activation and migration.
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Affiliation(s)
- Santos Mañes
- Department of Immunology and Oncology, National Center of Biotechnology/Consejo Superior de Investigaciones Científicas, Madrid, Spain.
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68
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Kim JE, White FM. Quantitative analysis of phosphotyrosine signaling networks triggered by CD3 and CD28 costimulation in Jurkat cells. THE JOURNAL OF IMMUNOLOGY 2006; 176:2833-43. [PMID: 16493040 DOI: 10.4049/jimmunol.176.5.2833] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mechanism by which stimulation of coreceptors such as CD28 contributes to full activation of TCR signaling pathways has been intensively studied, yet quantitative measurement of costimulation effects on functional TCR signaling networks has been lacking. In this study, phosphotyrosine networks triggered by CD3, CD28, or CD3 and CD28 costimulation were analyzed by site-specific quantitative phosphoproteomics, resulting in identification of 101 tyrosine and 3 threonine phosphorylation sites and quantification of 87 sites across four cell states. As expected, CD3 stimulation induced phosphorylation of CD3 chains and upstream components of TCR pathways such as Zap70, while CD28 stimulation induced phosphorylation of CD28, Vav-1, and other adaptor proteins including downstream of tyrosine kinase 1, Grb2-associated protein 2 (Grap2), and Wiskott-Aldrich syndrome protein. CD3 and CD28 costimulation induced a complex response including decreased threonine phosphorylation in the ERK1 and ERK2 activation loops and increased phosphorylation of selected tyrosine sites on ERK1/2, p38, phospholipase C-gamma, Src homology 2 domain-containing transforming protein 1, Grap2, and Vav-1, potentiating T cell activation. Hierarchical clustering and self-organizing maps were used to identify modules of coregulated phosphorylation sites within the network. Quantitative information in our study suggests quantitative and qualitative contribution by costimulation of CD28 on CD3-stimulated TCR signaling networks via enhanced phosphorylation of phospholipase C-gamma/Src homology 2 domain-containing transforming protein 1/Grap2/Vav-1 and their effects on downstream components including MAPKs.
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Affiliation(s)
- Ji-Eun Kim
- Biological Engineering Division, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Pavlick KP, Ostanin DV, Furr KL, Laroux FS, Brown CM, Gray L, Kevil CG, Grisham MB. Role of T-cell-associated lymphocyte function-associated antigen-1 in the pathogenesis of experimental colitis. Int Immunol 2006; 18:389-98. [PMID: 16415103 DOI: 10.1093/intimm/dxh378] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The beta2 integrin lymphocyte function-associated antigen-1 (LFA-1; CD11a/CD18) is important for lymphocyte trafficking and activation as well as recruitment to sites of tissue inflammation. The objective of this study was to assess the role of 'T-cell-associated' LFA-1 in the pathogenesis of chronic colitis in vivo. Transfer of CD4+CD25- T cells isolated from wild-type (wt) mice into immunodeficient recipients [recombinase-activating gene-1-deficient (RAG-1-/-] produced moderate to severe colitis, whereas RAG-1-/- mice injected with CD11a-deficient (CD11a-/-; LFA-1-/-) donor T cells displayed minimal macroscopic and histological evidence of colitis. Surface expression of L-selectin, alpha4, alpha4beta7 and chemokine receptor-7 were similar for wt and CD11a-/- donor T cells. Attenuated disease in the CD11a-/- --> RAG-1-/- animals was associated with decreased numbers of CD4+ T cells in the mesenteric lymph nodes (MLNs), spleen and intestinal lamina propria (LP). In addition, significant reductions in Th1 cytokines were observed following ex vivo stimulation of mononuclear cells obtained from the MLNs and colonic LP. Interestingly, mononuclear cells obtained from the spleens of CD11a-/- --> RAG-1-/- exhibited enhanced pro-inflammatory cytokine production compared with splenocytes obtained from wt --> RAG-1-/- colitic mice. Taken together, our data suggest that T-cell-associated CD11a (LFA-1) expression plays a dual role in the initiation of chronic gut inflammation by facilitating naive T-cell priming/activation and expansion within MLNs and by augmenting pro-inflammatory cytokine production following secondary stimulation by antigen-presenting cells in the colonic interstitium.
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Affiliation(s)
- Kevin P Pavlick
- Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, 1501 Kings Highway, P.O. Box 33932, Shreveport, LA 71130-3932, USA
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70
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Abstract
It is not unusual for antigens and potentially responsive T cells to co-exist in the same organism while these T cells remain silent and do not mount life-threatening immune responses. A rich array of mechanisms has been proposed to explain these observations. T cell silencing is controlled in multiple levels. Initially, dendritic cells and regulatory T cells appear to play critical roles. In addition, T cell immunity is tightly regulated by a molecular network of cytokines and cell receptor interactions by the opposed surfaces of antigen-presenting cells and T cells. Recognition of a specific antigen is therefore shaped and tuned by co-stimulatory and co-inhibitory receptor-ligand pairs. At last, immunologists are beginning to exploit the rules governing these assorted sounds of T cell silence.
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Affiliation(s)
- Ignacio Melero
- Department of Medicine, CIMA and Clinica Universitaria, University of Navarra, Pamplona, Spain.
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71
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Ly LH, Smith R, Switzer KC, Chapkin RS, McMurray DN. Dietary eicosapentaenoic acid modulates CTLA-4 expression in murine CD4+ T-cells. Prostaglandins Leukot Essent Fatty Acids 2006; 74:29-37. [PMID: 16221546 DOI: 10.1016/j.plefa.2005.09.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 09/04/2005] [Indexed: 10/25/2022]
Abstract
We have demonstrated that downregulation of proliferation by CD4(+) T-cells in mice fed n-3 PUFA diets is dependent on the involvement of CD28. Therefore, we hypothesized that the balance of co-stimulatory and downregulatory properties of CD28 and CTLA-4, respectively, would be altered by diet. Mice were fed a control corn oil (CO)-enriched diet devoid of n-3 PUFA, or diets enriched with either docosahexaenoic acid (DHA) or eicosapentaenoic acid (EPA) for 14d. The proliferation of splenic CD4(+) T-cells was suppressed by DHA and EPA following stimulation with anti-CD3 and anti-CD28. Surprisingly, the number of surface CD28 molecules was not reduced in activated CD4(+) T-cells from either group of n-3 PUFA-fed mice. However, in mice fed EPA, CTLA-4 protein levels were enhanced significantly 72 h post-activation (P<0.01). Therefore, we conclude that dietary EPA may suppress CD4(+) T-cell activation by enhancing the downregulatory co-receptor CTLA-4, while not altering the levels of CD28.
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MESH Headings
- Animals
- Antigens, CD
- Antigens, Differentiation/genetics
- Antigens, Differentiation/metabolism
- CD28 Antigens/genetics
- CD28 Antigens/metabolism
- CD4-Positive T-Lymphocytes/drug effects
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CTLA-4 Antigen
- Cell Proliferation/drug effects
- Corn Oil/pharmacology
- Dietary Fats, Unsaturated/administration & dosage
- Dietary Fats, Unsaturated/pharmacology
- Docosahexaenoic Acids/pharmacology
- Eicosapentaenoic Acid/pharmacology
- Fatty Acids/analysis
- Fatty Acids, Omega-3/administration & dosage
- Fatty Acids, Omega-3/pharmacology
- Female
- Gene Expression/drug effects
- Lymphocyte Activation/drug effects
- Mice
- Mice, Inbred C57BL
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Time Factors
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Affiliation(s)
- Lan H Ly
- Department of Nutrition and Food Science, Texas A&M University System Health Science Center, College Station, TX, USA
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72
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Chakraborty AK. Decoding communications between cells in the immune system using principles of chemical engineering. AIChE J 2006. [DOI: 10.1002/aic.690490702] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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73
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Weber MS, Prod'homme T, Steinman L, Zamvil SS. Drug Insight: using statins to treat neuroinflammatory disease. ACTA ACUST UNITED AC 2005; 1:106-12. [PMID: 16932506 DOI: 10.1038/ncpneuro0047] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Accepted: 09/23/2005] [Indexed: 11/10/2022]
Abstract
Statins, a family of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, are used primarily to reduce atherogenesis and cardiovascular morbidity. Surprisingly, they have also been shown to have immunomodulatory properties that might be of benefit for the treatment of autoimmune disorders. Statins can prevent and even reverse ongoing paralysis in experimental autoimmune encephalomyelitis--the mouse model for multiple sclerosis--and on the basis of these findings, statins are now being tested in patients with multiple sclerosis in clinical trials.
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Affiliation(s)
- Martin S Weber
- University of California San Francisco (UCSF), CA 94143, USA
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74
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Yokosuka T, Sakata-Sogawa K, Kobayashi W, Hiroshima M, Hashimoto-Tane A, Tokunaga M, Dustin ML, Saito T. Newly generated T cell receptor microclusters initiate and sustain T cell activation by recruitment of Zap70 and SLP-76. Nat Immunol 2005; 6:1253-62. [PMID: 16273097 DOI: 10.1038/ni1272] [Citation(s) in RCA: 543] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 10/06/2005] [Indexed: 11/09/2022]
Abstract
T cell receptor (TCR) activation and signaling precede immunological synapse formation and are sustained for hours after initiation. However, the precise physical sites of the initial and sustained TCR signaling are not definitively known. We report here that T cell activation was initiated and sustained in TCR-containing microclusters generated at the initial contact sites and the periphery of the mature immunological synapse. Microclusters containing TCRs, the tyrosine kinase Zap70 and the adaptor molecule SLP-76 were continuously generated at the periphery. TCR microclusters migrated toward the central supramolecular cluster, whereas Zap70 and SLP-76 dissociated from these microclusters before the microclusters coalesced with the TCR-rich central supramolecular cluster. Tyrosine phosphorylation and calcium influx were induced as microclusters formed at the initial contact sites. Inhibition of signaling prevented recruitment of Zap70 into the microclusters. These results indicated that TCR-rich microclusters initiate and sustain TCR signaling.
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Affiliation(s)
- Tadashi Yokosuka
- Laboratory for Cell Signaling, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
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75
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Wolf E, Hofmeister R, Kufer P, Schlereth B, Baeuerle PA. BiTEs: bispecific antibody constructs with unique anti-tumor activity. Drug Discov Today 2005; 10:1237-44. [PMID: 16213416 DOI: 10.1016/s1359-6446(05)03554-3] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Bispecific T-cell engager molecules (BiTEs) constitute a class of bispecific single-chain antibodies for the polyclonal activation and redirection of cytotoxic T cells against pathogenic target cells. BiTEs combine a unique set of properties that have not yet been reported for any other kind of bispecific antibody construct, namely extraordinary potency and efficacy against target cells at low T-cell numbers without the need for T-cell co-stimulation. Here we review novel insights into the mechanism of BiTE action, which help to explain the unique features of BiTEs, as well as data from various animal models demonstrating the outstanding therapeutic potential of BiTEs for the treatment of malignant diseases.
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Affiliation(s)
- Evelyn Wolf
- Micromet AG, Staffelseestr. 2, 81477 Munich, Germany
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76
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Haeryfar SMM, Conrad DM, Musgrave B, Hoskin DW. Antibody blockade of Thy-1 (CD90) impairs mouse cytotoxic T lymphocyte induction by anti-CD3 monoclonal antibody. Immunol Cell Biol 2005; 83:352-63. [PMID: 16033530 DOI: 10.1111/j.1440-1711.2005.01342.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thy-1 (CD90) expressed by mouse T cells is known to have signal transducing properties, but the ability of Thy-1 to enhance cytotoxic T lymphocyte (CTL) development is not well understood. Here we show that stimulation of mouse T cells with monoclonal antibodies (mAb) to CD3, CD28 and Thy-1 (clone G7), which were coimmobilized on polystyrene microbeads, resulted in a greater proliferative response than stimulation with only anti-CD3 and anti-CD28 mAb, indicating that Thy-1 cross-linking enhanced T cell receptor/CD28-driven T cell activation. Consistent with this finding, Thy-1 blockade with a soluble nonactivating anti-Thy-1 mAb (clone 30-H12) inhibited anti-CD3-induced proliferation of CD4+ and CD8+ T cells, and the induction of cytotoxic effector cells in a dose-dependent fashion. Interleukin-2 synthesis and CD25 expression were also impaired by Thy-1 blockade. The inhibitory effect involved a defect at or before the level of protein kinase C activation because the addition of phorbol ester ablated the anti-Thy-1-mediated inhibition of anti-CD3-induced T cell activation. The CTL that were induced in the presence of blocking anti-Thy-1 mAb adhered to target cells but showed reduced expression of granzyme B and perforin. In contrast, Fas ligand expression and function was not affected by Thy-1 blockade. We conclude that Thy-1 signalling promotes the in vitro generation of CTL that kill in a granule-dependent fashion.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacology
- Antigens, Differentiation/genetics
- CD3 Complex/immunology
- Cell Proliferation/drug effects
- Endopeptidases/genetics
- Gene Expression Regulation/drug effects
- Granzymes
- Interleukin-2/genetics
- Interleukin-2/pharmacology
- Membrane Proteins/genetics
- Mice
- Mice, Inbred C57BL
- Pore Forming Cytotoxic Proteins
- Protein Kinase C/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Interleukin-2/metabolism
- T-Lymphocytes, Cytotoxic/cytology
- T-Lymphocytes, Cytotoxic/drug effects
- T-Lymphocytes, Cytotoxic/immunology
- T-Lymphocytes, Cytotoxic/metabolism
- Thy-1 Antigens/immunology
- Thy-1 Antigens/metabolism
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Affiliation(s)
- S M Mansour Haeryfar
- Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, Halifax, Canada
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77
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Gilbert C, Bergeron M, Méthot S, Giguère JF, Tremblay MJ. Statins Could Be Used to Control Replication of Some Viruses, Including HIV-1. Viral Immunol 2005; 18:474-89. [PMID: 16212526 DOI: 10.1089/vim.2005.18.474] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Statins are mainly known for their plasma cholesterol-lowering properties and are widely used for the prevention of cardiovascular diseases. They however also exert pleiotropic effects through a variety of mechanisms, among which several immunosuppressive effects that are unrelated to their cholesterol-lowering activity. Interestingly, there has been recent evidence of antiviral effects, including preliminary studies on the efficacy of statins against HIV-1. This paper more particularly focuses on the specific inhibition of the binding of leukocyte function-associated antigen-1 (LFA-1) to intercellular adhesion molecule (ICAM-1) by statins, independently of the inhibition of HMGCoA reductase. Targeting the statin-binding site within LFA-1 or regulating LFA-1 affinity by inhibiting prenylation of the small GTPases could prove useful to treat inflammatory, autoimmune diseases and possibly viral infections, including HIV-1.
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Affiliation(s)
- Caroline Gilbert
- Research Center in Infectious Diseases, CHUL Research Center, Laval University, 2705 Laurier Boulevard, Quebec, Canada G1V 4G2
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78
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Abstract
T cells integrate and transduce the key signals necessary to mount an appropriate immune response. To do this, they rely on both secreted factors as well as physical cell-cell contact. Much attention has focused on the organization of proteins at the contact area between a T cell and an antigen-presenting cell, known as the immunological synapse. It has been shown in vitro that proteins segregate into two distinct regions within this contact area, a central area referred to as the c-SMAC, where the T cell receptor and associated signaling molecules are enriched, and a peripheral region called the p-SMAC containing LFA-1 and the scaffolding protein talin. Whether or not these structures form in vivo and how they function in T cell activation remain issues of great interest. Here, we review recently published work and propose several possible functions for the role of the c-SMAC in T cell activation.
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Affiliation(s)
- Joseph Lin
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA
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79
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Stephen TL, Niemeyer M, Tzianabos AO, Kroenke M, Kasper DL, Kalka-Moll WM. Effect of B7-2 and CD40 signals from activated antigen-presenting cells on the ability of zwitterionic polysaccharides to induce T-Cell stimulation. Infect Immun 2005; 73:2184-9. [PMID: 15784561 PMCID: PMC1087428 DOI: 10.1128/iai.73.4.2184-2189.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Carbohydrates have been thought to stimulate immune responses independently of T cells; however, zwitterionic polysaccharides (ZPSs) from the capsules of some bacteria elicit potent CD4+-T-cell responses in vivo and in vitro. We demonstrated that HLA-DR on professional antigen-presenting cells (APCs) is required for ZPS-induced T-cell proliferation in vitro (15). Recently, it was shown that ZPSs are processed to low-molecular-weight carbohydrates by a nitric oxide-mediated mechanism in endosomes and locate in the major histocompatibility complex class II pathway (5, 15). The effect of the ZPS-mediated expression of HLA-DR and costimulatory molecules on the APC and T-cell engagement and subsequent T-cell activation has not been elucidated. Herein, we report that ZPS-mediated induction of HLA-DR-surface expression and T-cell proliferation are maximally enhanced after incubation of APCs for 8 h with ZPS. Treatment of APCs with bafilomycin A inhibits the up-regulation of ZPS-mediated HLA-DR surface expression and leads to inhibition of T-cell proliferation. Monoclonal antibodies (MAbs) to the costimulatory molecules B7-2 and CD40L specifically block ZPS-mediated T-cell activation, while a MAb to B7-1 does not. Surface expression of B7-2 and B7-1 but not of CD40 is maximally enhanced at 8 to 16 h of treatment of APCs with ZPS. The results demonstrate that the cellular immune response to ZPS depends on the translocation of HLA-DR to the cell surface and requires costimulation via B7-2 and CD40 on activated APCs. The implication is that activation of ZPS-specific T cells requires an orchestrated arrangement of both presenting and costimulatory molecules to form an immunological synapse.
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Affiliation(s)
- Tom Li Stephen
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Medical Center, Goldenfelsstr. 19-21, 50935 Cologne, Germany
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80
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Molon B, Gri G, Bettella M, Gómez-Moutón C, Lanzavecchia A, Martínez-A C, Mañes S, Viola A. T cell costimulation by chemokine receptors. Nat Immunol 2005; 6:465-71. [PMID: 15821738 DOI: 10.1038/ni1191] [Citation(s) in RCA: 261] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2004] [Accepted: 03/10/2005] [Indexed: 12/15/2022]
Abstract
Signals mediated by chemokine receptors may compete with T cell receptor stop signals and determine the duration of T cell-antigen-presenting cell interactions. Here we show that during T cell stimulation by antigen-presenting cells, T cell chemokine receptors coupled to G(q) and/or G(11) protein were recruited to the immunological synapse by a G(i)-independent mechanism. When chemokine receptors were sequestered at the immunological synapse, T cells became insensitive to chemotactic gradients, formed more stable conjugates and finally responded with enhanced proliferation and cytokine production. We suggest that chemokine receptor trapping at the immunological synapse enhances T cell activation by improving T cell-antigen-presenting cell attraction and impeding the 'distraction' of successfully engaged T cells by other chemokine sources.
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Affiliation(s)
- Barbara Molon
- Venetian Institute of Molecular Medicine and Department of Biomedical Science, University of Padua, 35100 Padua, Italy
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81
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Stüve O, Prod'homme T, Slavin A, Youssef S, Dunn S, Steinman L, Zamvil SS. Statins and their potential targets in multiple sclerosis therapy. Expert Opin Ther Targets 2005; 7:613-22. [PMID: 14498824 DOI: 10.1517/14728222.7.5.613] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Multiple sclerosis (MS) is a CNS-demyelinating disease characterised by relapsing and chronic neurological impairment. While traditionally CNS autoantigen-specific CD4(+) T cells have been considered the culprits in the initial phase of the disease, recent observations have altered this concept. It is now recognised that other T lymphocyte subclasses can initiate CNS demyelination. In addition, other cell types and molecules may play an important role in MS pathogenesis. There is overwhelming evidence that MS is a dynamic process, in which recurrent episodes of blood-brain barrier disruption and CNS inflammation play a crucial role in early disease stages, leading eventually to the largely irreversible changes of demyelination, gliosis and axonal degeneration. These observations may have important therapeutic implications. Within the last ten years, several medications have been approved for MS treatment. These agents, all of which are given parenterally, are only partially effective and are often associated with adverse effects and potential toxicities. The number and different types of medications used for MS are likely to increase in the near future, as several novel therapies are currently tested in clinical trials. 3-hydroxy-3-methyglutaryl coenzyme A reductase inhibitors, 'statins', are cholesterol-lowering drugs that are given orally, are safe and have biological effects independent of their cholesterol-reducing properties. Recent reports have shown that statins have anti-inflammatory and neuroprotective properties that may be beneficial in the treatment of MS. This article will outline experimental evidence that suggests potential clinical benefits of statins for MS patients.
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Affiliation(s)
- Olaf Stüve
- Department of Neurology, University of California, San Francisco, 521 Parnassus Avenue, C-440, San Francisco, CA 94143-0114, USA
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82
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van den Berg HA, Rand DA. Foreignness as a matter of degree: the relative immunogenicity of peptide/MHC ligands. J Theor Biol 2005; 231:535-48. [PMID: 15488530 DOI: 10.1016/j.jtbi.2004.07.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2004] [Revised: 07/07/2004] [Accepted: 07/12/2004] [Indexed: 12/31/2022]
Abstract
The ability of T lymphocytes (T cells) to recognize and attack foreign invaders while leaving healthy cells unharmed is often analysed as a discrete self/non-self dichotomy, with each peptide/MHC ligand classified as either self or non-self. We argue that the ligand immunogenicity is more naturally treated as a continuous quantity, and show how to define and quantitate relative ligand immunogenicity. In our theory, self-tolerance is acquired through reduction of the relative immunogenicity of autoantigens, whereas xenoantigens, typically not presented during induction of deletional tolerance, retain a high degree of relative immunogenicity. Autoantigens that are not prominently presented in deletional tolerance likewise retain a high relative immunogenicity and remain essentially foreign. According to our analysis, any given autoantigen can attain a high level of relative immunogenicity, provided it is presented at sufficiently high levels. Our theory provides a quantitative tool to analyse the immunogenicity of tumour-associated neoantigens and the aetiology of autoimmune disease.
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Affiliation(s)
- Hugo A van den Berg
- Interdisciplinary Programme for Cellular Regulation, Mathematics Institute, University of Warwick, Coventry CV4 7AL, UK.
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83
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Cascio M. Connexins and their environment: effects of lipids composition on ion channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1711:142-53. [PMID: 15955299 DOI: 10.1016/j.bbamem.2004.12.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 11/25/2004] [Accepted: 12/02/2004] [Indexed: 11/16/2022]
Abstract
Intercellular communication is mediated through paired connexons that form an aqueous pore between two adjacent cells. These membrane proteins reside in the plasma membrane of their respective cells and their activity is modulated by the composition of the lipid bilayer. The effects of the bilayer on connexon structure and function may be direct or indirect, and may arise from specific binding events or the physicochemical properties of the bilayer. While the effects of the bilayer and its constituent lipids on gap junction activity have been described in the literature, the underlying mechanisms of the interaction of connexin with its lipidic microenvironment are not as well characterized. Given that the information regarding connexons is limited, in this review, the specific roles of lipids and the properties of the bilayer on membrane protein structure and function are described for other ion channels as well as for connexons.
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Affiliation(s)
- Michael Cascio
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, United States.
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84
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Tavano R, Gri G, Molon B, Marinari B, Rudd CE, Tuosto L, Viola A. CD28 and lipid rafts coordinate recruitment of Lck to the immunological synapse of human T lymphocytes. THE JOURNAL OF IMMUNOLOGY 2004; 173:5392-7. [PMID: 15494485 DOI: 10.4049/jimmunol.173.9.5392] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
In T lymphocytes, the Src family kinase Lck associates lipid rafts and accumulates at the immunological synapse (IS) during T cell stimulation by APCs. Using CD4- or CD28-deficient murine T cells, it was suggested that recruitment of Lck to the IS depends on CD4, whereas CD28 sustains Lck activation. However, in human resting T cells, CD28 is responsible for promoting recruitment of lipid rafts to the IS by an unknown mechanism. Thus, we performed a series of experiments to determine 1) whether Lck is recruited to the IS through lipid rafts; and 2) whether Lck recruitment to the IS of human resting T cells depends on CD4 or on CD28 engagement. We found that CD28, but not CD4, stimulation induced recruitment of Lck into detergent-resistant domains as well as its accumulation at the IS. We also found that Lck recruitment to the IS depends on the CD28 COOH-terminal PxxPP motif. Thus, the CD28-3A mutant, generated by substituting the prolines in positions 208, 211, and 212 with alanines, failed to induce Lck and lipid raft accumulation at the synapse. These results indicate that CD28 signaling orchestrates both Lck and lipid raft recruitment to the IS to amplify T cell activation.
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Affiliation(s)
- Regina Tavano
- Venetian Institute of Molecular Medicine and Department of Biomedical Science, University of Padua, Padua, Italy
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85
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Coombs D, Dembo M, Wofsy C, Goldstein B. Equilibrium thermodynamics of cell-cell adhesion mediated by multiple ligand-receptor pairs. Biophys J 2004; 86:1408-23. [PMID: 14990470 PMCID: PMC1303978 DOI: 10.1016/s0006-3495(04)74211-3] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In many situations, cell-cell adhesion is mediated by multiple ligand-receptor pairs. For example, the interaction between T cells and antigen-presenting cells of the immune system is mediated not only by T cell receptors and their ligands (peptide-major histocompatibility complex) but also by binding of intracellular adhesion molecules. Interestingly, these binding pairs have different resting lengths. Fluorescent labeling reveals segregation of the longer adhesion molecules from the shorter T cell receptors in this case. Here, we explore the thermal equilibrium of a general cell-cell interaction mediated by two ligand-receptor pairs to examine competition between the elasticity of the cell wall, nonspecific intercellular repulsion, and bond formation, leading to segregation of bonds of different lengths at equilibrium. We make detailed predictions concerning the relationship between physical properties of the membrane and ligand-receptor pairs and equilibrium pattern formation, and suggest experiments to refine our understanding of the system. We demonstrate our model by application to the T cell/antigen-presenting-cell system and outline applications to natural killer cell adhesion.
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Affiliation(s)
- Daniel Coombs
- Department of Mathematics, University of British Columbia, Vancouver, British Columbia V6T 1Z2, Canada.
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86
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Wang H, McCann FE, Gordan JD, Wu X, Raab M, Malik TH, Davis DM, Rudd CE. ADAP-SLP-76 binding differentially regulates supramolecular activation cluster (SMAC) formation relative to T cell-APC conjugation. ACTA ACUST UNITED AC 2004; 200:1063-74. [PMID: 15477347 PMCID: PMC2211848 DOI: 10.1084/jem.20040780] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
T cell–APC conjugation as mediated by leukocyte function-associated antigen-1 (LFA-1)–intercellular adhesion molecule (ICAM)-1 binding is followed by formation of the supramolecular activation cluster (SMAC) at the immunological synapse. The intracellular processes that regulate SMAC formation and its influence on T cell function are important questions to be addressed. Here, using a mutational approach, we demonstrate that binding of adaptor adhesion and degranulation promoting adaptor protein (ADAP) to SLP-76 differentially regulates peripheral SMAC (pSMAC) formation relative to conjugation. Although mutation of the YDDV sites (termed M12) disrupted SLP-76 SH2 domain binding and prevented the ability of ADAP to increase conjugation and LFA-1 clustering, M12 acted selectively as a dominant negative (DN) inhibitor of pSMAC formation, an effect that was paralleled by a DN effect on interleukin-2 production. ADAP also colocalized with LFA-1 at the immunological synapse. Our findings identify ADAP–SLP-76 binding as a signaling event that differentially regulates SMAC formation, and support a role for SMAC formation in T cell cytokine production.
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Affiliation(s)
- Hongyan Wang
- Molecular Immunology Section, Department of Immunology, Imperial College London, Hammersmith Campus, London W12 ONN, England, UK
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87
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Abstract
The existence of sphingolipid- and cholesterol-rich membrane microdomains called "lipid rafts", as well as their role in lymphocyte biology, has been widely debated during the last few years. Plasma membrane microdomains seem to be primarily involved in initiation and propagation of the signal transduction cascade associated with lymphocyte activation. In this review, we discuss the recent literature suggesting that, during lymphocyte activation and chemotaxis, lipid rafts act as platforms to compartmentalise signalling and facilitate specific protein-protein interactions.
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Affiliation(s)
- Paola Pizzo
- Department of Biomedical Sciences, University of Padova, Viale Giuseppe Colombo 3, I-35121, Italy.
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88
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Abstract
Human CD38 is a protein which catalyzes the synthesis of nicotinic acid adenine dinucleotide (NAADP+) and the conversion of NAD+ to cADPR. Both cADPR and NAADP+ are powerful intracellular Ca2+ ([Ca2+]i) mobilizers in different cell types. Recently, the presence of CD38 autoantibodies has been found in a significant number (9-15%) of patients with Type 2 or long-standing Type 1 diabetes. These autoantibodies are biologically active, the majority of them (-60%) displaying agonistic properties, i.e., [Ca2+]i mobilization in lymphocytic cell lines and in pancreatic islets. In cultured rat pancreatic islets, the human autoantibodies inhibit glucose-induced insulin release, whereas, in human pancreatic islets CD38 autoantibodies stimulate glucose-mediated insulin secretion. The clinical phenotype of anti-CD38-positive Type 2 diabetes differs from the LADA (latent autoimmune diabetes of adults) phenotype. When accurately matched for age and obesity, only LADA patients with anti-GAD antibodies, but not GAD-negative/ CD38-positive patients, have reduced in vivo beta-cell function in comparison to antibody-negative patients. Transgenic mice overexpressing CD38 show enhanced glucose-induced insulin release, whereas, conversely, CD38 knockout mice display a severe impairment in beta-cell function. Few Japanese diabetic patients carry a missense mutation in the CD38 gene; in Caucasian patients mutations in the CD38 gene have not been found. Collectively, these findings suggest that activation of CD38 represents an alternative signaling pathway for glucose-induced insulin secretion in human beta-cells. More information, however, is necessary to gauge the role of CD38 autoimmunity in the context of the natural history of human Type 1 or Type 2 diabetes.
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Affiliation(s)
- A Antonelli
- Metabolism Unit, Department of Internal Medicine and CNR Institute of Clinical Physiology, University of Pisa School of Medicine, Pisa, Italy.
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89
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Stüve O, Prod'homme T, Youssef S, Dunn S, Neuhaus O, Weber M, Hartung HP, Steinman L, Zamvil SS. Statins as potential therapeutic agents in multiple sclerosis. Curr Neurol Neurosci Rep 2004; 4:237-44. [PMID: 15102350 DOI: 10.1007/s11910-004-0044-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
3-Hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (ie, statins) are oral cholesterol-lowering drugs. Statins are well tolerated and have an excellent safety record. These agents competitively inhibit HMG CoA reductase, which is the enzyme that catalyzes the conversion of HMG CoA to L-mevalonate. Although L-mevalonate is a key intermediate in cholesterol synthesis, several of its metabolites are involved in post-translational modification of specific proteins involved in cell proliferation and differentiation. Thus, independent of their cholesterol-reducing properties, statins have important pleiotropic biologic effects. Recent reports indicate that statins have anti-inflammatory and neuroprotective properties. Whether statins will be of clinical benefit for patients with multiple sclerosis and other neurodegenerative diseases of the central nervous system will only be known after they are evaluated in prospective randomized clinical trials.
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Affiliation(s)
- Olaf Stüve
- Department of Neurology, University of California-San Francisco, 521 Parnassus Avenue, C-440, San Francisco, CA 94143-0114, USA
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90
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Perez OD, Mitchell D, Jager GC, Nolan GP. LFA-1 signaling through p44/42 is coupled to perforin degranulation in CD56+CD8+ natural killer cells. Blood 2004; 104:1083-93. [PMID: 15113754 DOI: 10.1182/blood-2003-08-2652] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Leukocyte function antigen 1 (LFA-1) is essential for the formation of immune cell synapses and plays a role in the pathophysiology of various autoimmune diseases. We investigated the molecular details of LFA-1 activation during adhesion between cytotoxic cells and a target model leukemia cell. The cytolytic activity of a CD3-CD8+CD56+ natural killer (NK) subset was enhanced when LFA-1 was activated. In a comparison of LFA-1 ligands, intercellular adhesion molecule 2 (ICAM-2) and ICAM-3 promoted LFA-1-directed perforin release, whereas ICAM-1 had little effect. Ligand-induced LFA-1 clustering facilitated perforin release, demonstrating LFA-1 could regulate degranulation mechanisms. LFA-1 induced the activation of src family kinases, Vav1 and p44/42 mitogen-activated protein kinase (MAPK), in human CD56+ NK cells as evidenced by intracellular phospho-epitope measurements that correlated with effector-target cell binding and perforin-granzyme A-mediated cytolytic activity. These results identify novel, specific functional consequence of LFA-1-mediated cytolytic activity in perforin-containing human NK subsets.
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Affiliation(s)
- Omar D Perez
- Baxter Laboratory for Genetic Pharmacology, Stanford University School of Medicine, Stanford, CA, USA
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91
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Affiliation(s)
- Beverley Wilkinson
- Molecular Immunology Section, Department of Immunology, Division of Investigative Sciences, Faculty of Medicine, Imperial College London, London, UK
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92
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Samstag Y, Nebl G. Interaction of cofilin with the serine phosphatases PP1 and PP2A in normal and neoplastic human T lymphocytes. ADVANCES IN ENZYME REGULATION 2004; 43:197-211. [PMID: 12791392 DOI: 10.1016/s0065-2571(02)00031-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Yvonne Samstag
- Institute for Immunology, Ruprecht-Karls-University, Im Neuenheimer Feld 305, D-69120, Heidelberg, Germany.
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93
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Raychaudhuri S, Chakraborty AK, Kardar M. Effective membrane model of the immunological synapse. PHYSICAL REVIEW LETTERS 2003; 91:208101. [PMID: 14683399 DOI: 10.1103/physrevlett.91.208101] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2003] [Indexed: 05/24/2023]
Abstract
The immunological synapse is a patterned collection of different types of receptors and ligands that forms in the intercellular junction between T cells and antigen presenting cells during recognition. The synapse is implicated in information transfer between cells, and is characterized by different spatial patterns of receptors at different stages in the life cycle of T cells. We obtain a minimalist model that captures this experimentally observed phenomenology. A functional renormalization group analysis provides further insights.
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Affiliation(s)
- Subhadip Raychaudhuri
- Department of Chemical Engineering, University of California Berkeley, Berkeley, California 94720, USA
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94
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Wang Y, Gao D, Lunsford KE, Frankel WL, Bumgardner GL. Targeting LFA-1 synergizes with CD40/CD40L blockade for suppression of both CD4-dependent and CD8-dependent rejection. Am J Transplant 2003; 3:1251-8. [PMID: 14510698 DOI: 10.1046/j.1600-6143.2003.00201.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Allogeneic hepatocytes elicit CD4-dependent and (CD4-independent) CD8+ T-cell-initiated graft rejection. The (CD4-independent) CD8+ T-cell pathway is resistant to immunosuppressive strategies that readily and indefinitely suppress CD4+ T-cell-dependent rejection responses. Consequently, successful immunoregulation of hepatocyte-initiated immune responses requires a strategy which regulates both CD4-dependent and CD8-dependent rejection responses. Interference with CD40/CD40 ligand (CD40L) costimulation only transiently suppresses CD4- and CD8-dependent hepatocyte rejection. Interference with CD28/B7 costimulation transiently suppresses CD4-dependent hepatocyte rejection, but is ineffective for suppression of CD8-dependent hepatocyte rejection. To date, hepatocyte survival > 60 days post-transplant has not been achieved by any immunotherapeutic strategy. In the current study, we evaluated a novel immunosuppressive strategy which targets both LFA-1 and CD40L-mediated signals. Targeting LFA-1 suppressed (CD4-independent) CD8+ T-cell-initiated hepatocyte rejection such that allogeneic hepatocyte survival > 60 days was achieved in 70% of CD4 KO mice. Targeting both LFA-1-mediated signals and CD40/CD40L costimulation resulted in synergistic effects, such that hepatocellular survival > 60 days was achieved in 100% of C57BL/6 mice (which have both CD4- and CD8-dependent T-cell pathways available).
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Affiliation(s)
- Yue Wang
- Department of Surgery, The Ohio State University Medical Center, Columbus, OH, USA
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95
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Abstract
Recent advances have been made in understanding the basis of T-cell signaling with the identification of hematopoeitic-specific adaptor proteins, or molecular scaffolds that facilitate protein complex formation and the integration of signals from the surface of T cells. Their potential relevance as targets in the modulation of transplantation relates to their immune-cell-specific expression and their ability to integrate signals needed for T-cell/APC conjugate formation, cytokine production and the clonal expansion of T cells. While LAT, GADS and SLP-76 are needed for TcR-induced cytokine production, the adaptors ADAP, VAV and SKAP-55 play specialized roles in the regulation of integrin adhesion and conjugation. Given the importance of these functions to the reactivity of T cells to allodeterminants of tissue grafts (GvH), and in the recognition and destruction of leukemic cells (GvL), these adaptors represent a new generation of potential targets in the modulation of transplantation.
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Affiliation(s)
- Christopher E Rudd
- Department of Immunology, Faculty of Medicine, Imperial College London, London, UK.
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96
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van den Berg HA, Rand DA. Antigen presentation on MHC molecules as a diversity filter that enhances immune efficacy. J Theor Biol 2003; 224:249-67. [PMID: 12927531 DOI: 10.1016/s0022-5193(03)00162-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
We consider the way in which antigen is presented to T cells on MHC molecules and ask how MHC peptide presentation could be optimized so as to obtain an effective and safe immune response. By analysing this problem with a mathematical model of T-cell activation, we deduce the need for both MHC restriction and high presentation selectivity. We find that the optimal selectivity is such that about one pathogen-derived peptide is presented per MHC isoform, on the average. We also indicate upper and lower bounds to the number of MHC isoforms per individual based on detectability requirements. Thus we deduce that an important role of MHC presentation is to act as a filter that limits the diversity of antigen presentation.
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97
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Ishida D, Yang H, Masuda K, Uesugi K, Kawamoto H, Hattori M, Minato N. Antigen-driven T cell anergy and defective memory T cell response via deregulated Rap1 activation in SPA-1-deficient mice. Proc Natl Acad Sci U S A 2003; 100:10919-24. [PMID: 12958214 PMCID: PMC196903 DOI: 10.1073/pnas.1834525100] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
SPA-1 is a principal Rap1 GTPase-activating protein in the hematopoietic progenitors and peripheral T cells, and SPA-1-deficient mice develop a spectrum of myeloproliferative stem cell disorders of late onset. In the present study, we show that SPA-1-deficient mice develop age-dependent T cell unresponsiveness preceding the myeloid disorders, whereas the T cell numbers remained unchanged. Progression of the T cell dysfunction was attributed to the age-dependent increase in CD44high T cell population that was unresponsive to T cell receptor stimulation. Younger SPA-1-deficient mice exhibited selectively impaired recall T cell responses against a T-dependent antigen with normal primary antibody response. These results suggested that the unresponsiveness of CD44high T cells was antigen-driven in vivo. T cells from younger SPA-1-/- mice showed much greater and more persisted Rap1 activation by anti-CD3 stimulation than control T cells. Furthermore, freshly isolated T cells from SPA-1-/- mice exhibited progressive accumulation of Rap1GTP as mice aged. T cells from aged SPA-1-/- mice with high amounts of Rap1GTP showed normal or even enhanced Ras activation with little extracellular signal-regulated kinase activation in response to anti-CD3 stimulation, indicating that excess Rap1GTP induced the uncoupling of Ras-mediated extracellular signal-regulated kinase activation. These results suggested that antigenic activation of naïve T cells in SPA-1-/- mice was followed by anergic rather than memory state due to the defective down-regulation of Rap1 activation, resulting in the age-dependent progression of overall T cell immunodeficiency.
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Affiliation(s)
- Daisuke Ishida
- Department of Immunology and Cell Biology, Graduate School of Biostudies, Kyoto University, Japan
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98
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Shanmugalakshmi S, Dheenadhayalan V, Muthuveeralakshmi P, Arivarignan G, Pitchappan RM. Mycobacterium bovis BCG scar status and HLA class II alleles influence purified protein derivative-specific T-cell receptor V beta expression in pulmonary tuberculosis patients from southern India. Infect Immun 2003; 71:4544-53. [PMID: 12874334 PMCID: PMC166027 DOI: 10.1128/iai.71.8.4544-4553.2003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Purified protein derivative (PPD) RT23-recalled T-cell receptor (TCR) V beta expression was studied in the peripheral blood of 42 pulmonary tuberculosis patients and 44 healthy controls from southern India, a region where tuberculosis is endemic. Forty-eight-hour whole-blood cultures in the presence or absence of PPD-RT23 were set up, and at the end of the culture period total RNA was extracted and cDNA was synthesized. Expression of various TCR V beta families was assessed by using family-specific primers. PPD-specific expression (usage) of TCR V beta families 4, 6, 8 to 12, and 14 was found in more controls than patients. Among the responders (individuals who showed PPD-specific expression), endemic controls had significantly higher responses than the patients had for TCR V beta families 2, 3, 7, 13, and 17. The majority of the patients did not show usage of most of the TCR V beta families, and this was attributed to T-cell downregulation. A four-way nested classification analysis revealed that TCR V beta family 1, 5, 9, 12, and 13 usage in the context of HLA class II high-risk alleles (DRB1*1501, DRB1*08, and DQB1*0601) and Mycobacterium bovis BCG scar status were the determining factors in susceptibility and resistance to tuberculosis. The healthier status of controls was attributed to the wider usage of many TCR V beta families readily recalled by PPD, while the disease status of the patients was attributed to TCR V beta downregulation and the resultant T-cell (memory cell?) unresponsiveness. Host genetics (HLA status) and BCG vaccination (scar status) seem to play important roles in skewing the immune response in adult susceptibility to pulmonary tuberculosis through TCR V beta usage.
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Affiliation(s)
- S Shanmugalakshmi
- Department of Immunology, School of Biological Sciences, Madurai Kamaraj University, Madurai 625021, India
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99
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Abstract
Many studies have shown the central importance of the co-receptors CD28, inducible costimulatory molecule (ICOS) and cytotoxic T lymphocyte antigen 4 (CTLA4) in the regulation of many aspects of T-cell function. CD28 and ICOS have both overlapping and distinct functions in the positive regulation of T-cell responses, whereas CTLA4 negatively regulates the response. The signalling pathways that underlie the function of each of the co-receptors indicate their shared and unique properties and provide compelling hints of functions that are as yet uncovered. Here, we outline the shared and distinct signalling events that are associated with each of the co-receptors and provide unifying concepts that are related to signalling functions of these co-receptors.
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Affiliation(s)
- Christopher E Rudd
- Molecular Immunology Section, Department of Immunology, Division of Investigative Science, Faculty of Medicine, Imperial College London, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK.
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100
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Fais S, Malorni W. Leukocyte uropod formation and membrane/cytoskeleton linkage in immune interactions. J Leukoc Biol 2003; 73:556-63. [PMID: 12714569 DOI: 10.1189/jlb.1102568] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The acquisition of a cell polarity is a crucial requirement for migration, activation, and apoptosis of leukocytes. The polarization of leukocytes involves the formation of two distinct poles: the leading edge--the attachment cell site to the substrate allowing directional movements of the cell--and on the opposite side, the uropod--mostly involved in cell-to-cell interaction and in a variety of leukocyte activities including activation and apoptosis. However, the uropod takes shape in neutrophils, monocytes, and natural killer cells, and the formation of this cell protrusion seems to exert an important role in immune interactions. In fact, the polarization sites of leukocytes are involved in a complex cross-talk between cells and extracellular matrix components, and a number of receptors and counter-receptors crowd in the contact sites to allow efficient cell-to-cell or cell-substrate interaction. The membrane/cytoskeleton interaction plays a crucial role in tuning these activities and in "predisposing" leukocytes to their function through the acquisition of a polarized phenotype. This review is focused on the mechanisms underlying the formation of the leukocyte uropod, the role of cytoskeleton in defining its structure and function, and the involvement of the uropod in the complex interplay between immune cells.
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Affiliation(s)
- Stefano Fais
- Laboratory of Immunology, Istituto Superiore di Sanità, Rome, Italy.
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