A stromal cell-derived membrane protein that supports hematopoietic stem cells.
Ueno H, Sakita-Ishikawa M, Morikawa Y, Nakano T, Kitamura T, Saito M.
Virology Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
Hematopoietic stem cells cannot be maintained in vitro without stromal cells, even if they are provided with growth factors, and it is likely that supportive cells in the bone marrow express membrane or secreted proteins that maintain hematopoiesis. Here we show that mKirre, a mammalian homolog of the gene kirre of Drosophila melanogaster, encodes a type Ia membrane protein that is involved in the hematopoietic supportive capacity of OP9 mouse stromal cells. Repressing mKirre expression with a short interfering RNA significantly reduced this supportive capacity. Our data suggest that mKirre is cleaved by metalloproteinases and that the extracellular domain of mKirre is responsible for supporting hematopoietic stem cells. These results contribute to our understanding of the mechanisms by which the hematopoietic microenvironment regulates hematopoiesis.
Nature. 2003 May 22;423(6938):409-14.
A role for Wnt signalling in self-renewal of haematopoietic stem cells.
Reya T, Duncan AW, Ailles L, Domen J, Scherer DC, Willert K, Hintz L, Nusse R, Weissman IL.
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Haematopoietic stem cells (HSCs) have the ability to renew themselves and to give rise to all lineages of the blood; however, the signals that regulate HSC self-renewal remain unclear. Here we show that the Wnt signalling pathway has an important role in this process. Overexpression of activated beta-catenin expands the pool of HSCs in long-term cultures by both phenotype and function. Furthermore, HSCs in their normal microenvironment activate a LEF-1/TCF reporter, which indicates that HCSs respond to Wnt signalling in vivo. To demonstrate the physiological significance of this pathway for HSC proliferation we show that the ectopic expression of axin or a frizzled ligand-binding domain, inhibitors of the Wnt signalling pathway, leads to inhibition of HSC growth in vitro and reduced reconstitution in vivo. Furthermore, activation of Wnt signalling in HSCs induces increased expression of HoxB4 and Notch1, genes previously implicated in self-renewal of HSCs. We conclude that the Wnt signalling pathway is critical for normal HSC homeostasis in vitro and in vivo, and provide insight into a potential molecular hierarchy of regulation of HSC development.
Proc Natl Acad Sci U S A. 2003 Jul 8;100(14):8384-8.
Identification of the beta cell antigen targeted by a prevalent population of pathogenic CD8+ T cells in autoimmune diabetes.
Lieberman SM, Evans AM, Han B, Takaki T, Vinnitskaya Y, Caldwell JA, Serreze DV, Shabanowitz J, Hunt DF, Nathenson SG, Santamaria P, DiLorenzo TP.
Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
Type 1 diabetes is an autoimmune disease in which autoreactive T cells attack and destroy the insulin-producing pancreatic beta cells. CD8+ T cells are essential for this beta cell destruction, yet their specific antigenic targets are largely unknown. Here, we reveal that the autoantigen targeted by a prevalent population of pathogenic CD8+ T cells in nonobese diabetic mice is islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP). Through tetramer technology, IGRP-reactive T cells are readily detected in islets and peripheral blood directly ex vivo. The human IGRP gene maps to a diabetes susceptibility locus, suggesting that IGRP also may be an antigen for pathogenic T cells in human type 1 diabetes and, thus, a new, potential target for diagnostic and therapeutic approaches.
Immunity. 2003 Jul;19(1):47-57.
Distinct dendritic cell populations sequentially present antigen to CD4 T cells and stimulate different
aspects of cell-mediated immunity.
Itano AA, McSorley SJ, Reinhardt RL, Ehst BD, Ingulli E, Rudensky AY, Jenkins MK.
Department of Microbiology, Center for Immunology, University of Minnesota Medical School,
Minneapolis, MN 55455, USA.
Peptide:MHC II complexes derived from a fluorescent antigen were detected in vivo to identify the cells that present subcutaneously injected antigen to CD4 T cells. Skin-derived dendritic cells (DCs) that acquired the antigen while in the draining lymph nodes were the first cells to display peptide:MHC II complexes. Presentation by these cells induced CD69, IL-2 production, and maximal proliferation by the T cells. Later, DCs displaying peptide:MHC II complexes migrated from the injection site via a G protein-dependent mechanism. Presentation by these migrants sustained expression of the IL-2 receptor and promoted delayed type hypersensitivity. Therefore, presentation of peptide:MHC II complexes derived from a subcutaneous antigen occurs in two temporally distinct waves with different functional consequences.
Nature. 2003 Jul 17;424(6946):329-34.
Impairment of dendritic cells and adaptive immunity by anthrax lethal toxin.
Agrawal A, Lingappa J, Leppla SH, Agrawal S, Jabbar A, Quinn C, Pulendran B.
Emory Vaccine Research Center, 954 Gatewood Road, Atlanta, Georgia 30329, USA.
Anthrax poses a clear and present danger as an agent of biological terrorism. Infection with Bacillus anthracis, the causative agent of anthrax, if untreated can result in rampant bacteraemia, multisystem dysfunction and death. Anthrax lethal toxin (LT) is a critical virulence factor of B. anthracis, which occurs as a complex of protective antigen and lethal factor. Here we demonstrate that LT severely impairs the function of dendritic cells--which are pivotal to the establishment of immunity against pathogens--and host immune responses by disrupting the mitogen-activated protein (MAP) kinase intracellular signalling network. Dendritic cells exposed to LT and then stimulated with lipopolysaccharide do not upregulate co-stimulatory molecules, secrete greatly diminished amounts of proinflammatory cytokines, and do not effectively stimulate antigen-specific T cells in vivo. Furthermore, injections of LT induce a profound impairment of antigen-specific T- and B-cell immunity. These data suggest a role for LT in suppressing host immunity during B. anthracis infections, and represent an immune evasion strategy, where a microbe targets MAP kinases in dendritic cells to disarm the immune response.
Nat Med. 2003 Aug;9(8):1039-46.
Apoptosis facilitates antigen presentation to T lymphocytes through MHC-I and CD1 in tuberculosis.
Schaible UE, Winau F, Sieling PA, Fischer K, Collins HL, Hagens K, Modlin RL, Brinkmann V, Kaufmann SH.
Max-Planck Institute for Infection Biology, Department of Immunology, Schumannstrasse 21-22, D-10117 Berlin, Germany.
Protective immunity against Mycobacterium tuberculosis involves major histocompatibility complex class I (MHC-I)- and CD1-restricted CD8 T cells, but the mechanisms underlying antigen delivery to antigen-presenting molecules remain enigmatic. Macrophages, the primary host cells for mycobacteria, are CD1-negative. Here we show that M. tuberculosis phagosomes are secluded from the cytosolic MHC-I processing pathway and that mycobacteria-infected cells lose their antigen-presenting capacity. We also show that mycobacteria induce apoptosis in macrophages, causing the release of apoptotic vesicles that carry mycobacterial antigens to uninfected antigen-presenting cells (APCs). Inhibition of apoptosis reduced transfer of antigens to bystander cells and activation of CD8 T cells. Uninfected dendritic cells, which engulfed extracellular vesicles, were indispensable for subsequent cross-presentation of antigens, through MHC-I and CD1b, to T cells from mycobacteria-sensitized donors. This new 'detour' pathway for presentation of antigens from a phagosome-contained pathogen shows the functional significance of infection-induced apoptosis in the activation of CD8 T cells specific for both protein and glycolipid antigens in tuberculosis.
Immunity. 2003 Jun;18(6):863-73.
B7S1, a novel B7 family member that negatively regulates T cell activation.
Prasad DV, Richards S, Mai XM, Dong C.
Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195, USA.
T cell activation by antigen-presenting cells (APC) is regulated by positive and negative costimulatory molecules in the B7 family. Here we describe a novel addition in this family, designated as B7S1, which is uniquely anchored to the cell membrane via a GPI linkage. B7S1 is expressed on professional APC and widely distributed in nonlymphoid tissues. A soluble B7S1-Ig fusion protein binds to activated but not naive T cells. B7S1-Ig inhibits T cell activation and IL-2 production. A monoclonal antibody that blocks binding of B7S1 to its receptor enhances T cell proliferation in vitro and exacerbates experimental autoimmune encephalomyelitis in vivo. This study identifies a novel negative regulator of T cell activation and further reveals complex costimulatory regulation of immune responses.
Nat Immunol. 2003 Jul;4(7):664-9.
The inhibitory function of B7 costimulators in T cell responses to foreign and self-antigens.
Lohr J, Knoechel B, Jiang S, Sharpe AH, Abbas AK.
Department of Pathology, University of California San Francisco School of Medicine, San Francisco,
California 94143-0511, USA.
When antigen-presenting cells (APCs) encounter inflammatory stimuli, they up-regulate their expression of B7. A small amount of B7 is also constitutively expressed on resting APCs, but its function is unclear. Here we show that initiation of T cell responses requires the expression of B7 on immunizing APCs, but the responses are much greater in the absence of basal B7 expression. Transfer of antigen-specific CD4+CD25+ cells reverses the increased responsiveness, and tolerance to a self-protein is broken by immunization in the absence of basal B7, thereby inducing autoimmunity. Similar loss of self-tolerance is seen on depletion of CD25+ cells. Thus, constitutively expressed B7 costimulators function to suppress T cell activation and maintain self-tolerance, principally by sustaining a population of regulatory T cells.
Immunity. 2003 Aug;19(2):281-94.
CD8 T Cell-Specific Downregulation of Histone Hyperacetylation and Gene Activation of the IL-4 Gene Locus by ROG, Repressor of GATA.
Omori M, Yamashita M, Inami M, Ukai-Tadenuma M, Kimura M, Nigo Y, Hosokawa H, Hasegawa A, Taniguchi M, Nakayama T.
Department of Molecular Immunology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana Chuo-ku, 260-8670, Chiba, Japan
Chromatin remodeling of type 2 cytokine gene loci occurs during differentiation of naive CD4 and CD8 T cells into type 2 helper (Th2) and cytotoxic (Tc2) T cells. IL-4 production and histone hyperacetylation in IL-4-associated nucleosomes in developing Tc2 cells were significantly lower than those of Th2 cells; however, cytokine production and histone hyperacetylation of IL-5 and IL-13 genes were equivalent. Developing Tc2 cells expressed lower GATA3 levels and dramatically increased levels of repressor of GATA (ROG). A ROG response element in the IL-13 gene exon 4 displayed Tc2-specific binding of ROG, HDAC1, and HDAC2 and exhibited repression of IL-4 gene activation. Thus, ROG may confer CD8 T cell-specific repression of histone hyperacetylation and activation of the IL-4 gene locus.
Original antigenic sin and apoptosis in the pathogenesis of dengue hemorrhagic fever.
Mongkolsapaya J, Dejnirattisai W, Xu XN, Vasanawathana S, Tangthawornchaikul N, Chairunsri A, Sawasdivorn S, Duangchinda T, Dong T, Rowland-Jones S, Yenchitsomanus PT, McMichael A, Malasit P, Screaton G.
MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, OX3 9DS, UK.
Dengue virus presents a growing threat to public health in the developing world. Four major serotypes of dengue virus have been characterized, and epidemiological evidence shows that dengue hemorrhagic fever (DHF), the more serious manifestation of the disease, occurs more frequently upon reinfection with a second serotype. We have studied dengue virus-specific T-cell responses in Thai children. During acute infection, few dengue-responsive CD8+ T cells were recovered; most of those present showed an activated phenotype and were undergoing programmed cell death. Many dengue-specific T cells were of low affinity for the infecting virus and showed higher affinity for other, probably previously encountered strains. Profound T-cell activation and death may contribute to the systemic disturbances leading to DHF, and original antigenic sin in the T-cell responses may suppress or delay viral elimination, leading to higher viral loads and increased immunopathology.
Science. 2003 Aug 22;301(5636):1099-102.
Helicobacter pylori vacuolating cytotoxin inhibits T lymphocyte activation.
Gebert B, Fischer W, Weiss E, Hoffmann R, Haas R.
Max von Pettenkofer-Institut fur Hygiene und Medizinische Mikrobiologie, LMU Munchen, Germany.
Helicobacter pylori (Hp) vacuolating cytotoxin VacA induces cellular vacuolation in epithelial cells. We found that VacA could efficiently block proliferation of T cells by inducing a G1/S cell cycle arrest. It interfered with the T cell receptor/interleukin-2 (IL-2) signaling pathway at the level of the Ca2+-calmodulin-dependent phosphatase calcineurin. Nuclear translocation of nuclear factor of activated T cells (NFAT), a transcription factor acting as a global regulator of immune response genes, was abrogated, resulting in down-regulation of IL-2 transcription. VacA partially mimicked the activity of the immunosuppressive drug FK506 by possibly inducing a local immune suppression, explaining the extraordinary chronicity of Hp infections.
Nature. 2003 Jul 10;424(6945):213-9.
Comment in: Nature. 2003 Jul 10;424(6945):136-7.
HIV-1 Nef intersects the macrophage CD40L signalling pathway to promote resting-cell infection.
Swingler S, Brichacek B, Jacque JM, Ulich C, Zhou J, Stevenson M.
Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street,
Worcester, Massachusetts 01605, USA.
All primate lentiviruses (HIV-1, HIV-2, SIV) encode Nef proteins, which are important for viral replication and pathogenicity in vivo. It is not known how Nef regulates these processes. It has been suggested that Nef protects infected cells from apoptosis and recognition by cytotoxic T lymphocytes. Other studies suggest that Nef influences the activation state of the infected cell, thereby enhancing the ability of that cell to support viral replication. Here we show that macrophages that express Nef or are stimulated through the CD40 receptor release a paracrine factor that renders T lymphocytes permissive to HIV-1 infection. This activity requires the upregulation of B-cell receptors involved in the alternative pathway of T-lymphocyte stimulation. T lymphocytes stimulated through this pathway become susceptible to viral infection without progressing through the cell cycle. We identify two proteins, soluble CD23 and soluble ICAM, that are induced from macrophages by Nef and CD40L, and which mediate their effects on lymphocyte permissivity. Our results reveal a mechanism by which Nef expands the cellular reservoir of HIV-1 by permitting the infection of resting T lymphocytes.
Nat Immunol. 2003 Aug;4(8):765-72.
Costimulation through the inducible costimulator ligand is essential for both T helper and B cell functions in T cell-dependent B cell responses.
Mak TW, Shahinian A, Yoshinaga SK, Wakeham A, Boucher LM, Pintilie M, Duncan G, Gajewska BU, Gronski M, Eriksson U, Odermatt B, Ho A, Bouchard D, Whorisky JS, Jordana M, Ohashi PS, Pawson T, Bladt F, Tafuri A.
Advanced Medical Discovery Institute, and Ontario Cancer Institute, Department of Medical Biophysics , University of Toronto, Toronto, Ontario M5G 2C1, Canada.
Costimulation through the inducible costimulator (ICOS) and its ligand (ICOSL) is essential for T cell-dependent B cell responses, but the cellular and temporal dynamics underlying its in vivo effects are poorly defined. Here we have shown that Icosl(-/-) and Icos(-/-) mice had similar phenotypes and that ICOS-ICOSL costimulation modulated the early but not late phases of IgG1 affinity maturation. Exploiting the adoptive transfer of T or B cells from primed Icosl(-/-) mice, we provided genetic evidence that costimulation through ICOSL was essential for primary but not secondary helper T cell responses and for the control of both T and B cell activities, resulting in T cell-dependent IgG1 production.
DNA deamination mediates innate immunity to retroviral infection.
Harris RS, Bishop KN, Sheehy AM, Craig HM, Petersen-Mahrt SK, Watt IN, Neuberger MS, Malim
MH.
Medical Research Council Laboratory of Molecular Biology, Hills Road, CB2 2QH, Cambridge, United
Kingdom.
CEM15/APOBEC3G is a cellular protein required for resistance to infection by virion infectivity factor (Vif)-deficient human immunodeficiency virus (HIV). Here, using a murine leukemia virus (MLV)-based system, we provide evidence that CEM15/APOBEC3G is a DNA deaminase that is incorporated into virions during viral production and subsequently triggers massive deamination of deoxycytidine to deoxyuridine within the retroviral minus (first)-strand cDNA, thus providing a probable trigger for viral destruction. Furthermore, HIV Vif can protect MLV from this CEM15/APOBEC3G-dependent restriction. These findings imply that targeted DNA deamination is a major strategy of innate immunity to retroviruses and likely also contributes to the sequence variation observed in many viruses (including HIV).
Immunity. 2003 Jun;18(6):813-23.
Comment in: Immunity. 2003 Jun;18(6):722-4.
Legionella reveal dendritic cell functions that facilitate selection of antigens for MHC class II presentation.
Neild AL, Roy CR.
Section of Microbial Pathogenesis, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, 06536, New Haven, CT, USA
To understand how adaptive immune responses are generated against bacteria that avoid being delivered to lysosomes, interactions between professional antigen-presenting cells (APCs) and the intracellular pathogen Legionella pneumophila were examined. In contrast to murine bone marrow-derived macrophages (BMMs), we show that dendritic cells (DCs) restrict the growth of intracellular Legionella. Similar to what has been reported in BMMs, phagosomes containing Legionella matured into endoplasmic reticulum (ER)-derived organelles after DC internalization. Biogenesis of an ER-derived vacuole did not effectively sequester Legionella antigens from presentation on MHC class II molecules (MHC II). It was determined that proteins synthesized after Legionella had established residence in an ER-derived vacuole were presented by infected APCs. These data indicate that the ability of DCs to restrict intracellular growth of Legionella could be an important property that facilitates priming of protective T cell-mediated immune responses to vacuolar pathogens.
Immunity. 2003 Jul;19(1):59-70.
TNF/iNOS-producing dendritic cells mediate innate immune defense against bacterial infection.
Serbina NV, Salazar-Mather TP, Biron CA, Kuziel WA, Pamer EG.
Infectious Disease Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, Immunology Program, Sloan-Kettering Institute, 1275 York Avenue, New York, NY 10021, USA.
Dendritic cells (DCs) present microbial antigens to T cells and provide inflammatory signals that modulate T cell differentiation. While the role of DCs in adaptive immunity is well established, their involvement in innate immune defenses is less well defined. We have identified a TNF/iNOS-producing (Tip)-DC subset in spleens of Listeria monocytogenes-infected mice that is absent from CCR2-deficient mice. The absence of Tip-DCs results in profound TNF and iNOS deficiencies and an inability to clear primary bacterial infection. CD8 and CD4 T cell responses to L. monocytogenes antigens are preserved in CCR2-deficient mice, indicating that Tip-DCs are not essential for T cell priming. Tip-DCs, as the predominant source of TNF and iNOS during L. monocytogenes infection, orchestrate and mediate innate immune defense against this intracellular bacterial pathogen.
Nat Immunol. 2003 Jun;4(6):540-5.
Comment in: Nat Immunol. 2003 Jun;4(6):507-9.
SOCS3 negatively regulates IL-6 signaling in vivo.
Croker BA, Krebs DL, Zhang JG, Wormald S, Willson TA, Stanley EG, Robb L, Greenhalgh CJ, Forster I, Clausen BE, Nicola NA, Metcalf D, Hilton DJ, Roberts AW, Alexander WS.
Cancer and Haematology Division, The Walter and Eliza Hall Institute of Medical Research and the Cooperative Research Centre for Cellular Growth Factors, 1G Royal Parade, Parkville, Victoria 3050, Australia.
Members of the suppressor of cytokine signaling (SOCS) family are potentially key physiological negative regulators of interleukin-6 (IL-6) signaling. To examine whether SOCS3 is involved in regulating this signaling, we have used conditional gene targeting to generate mice lacking Socs3 in the liver or in macrophages. We show that Socs3 deficiency results in prolonged activation of signal transducer and activator of transcription 1 (STAT1) and STAT3 after IL-6 stimulation but normal activation of STAT1 after stimulation with interferon-gamma (IFN-gamma). Conversely, IL-6-induced STAT activation is normal in Socs1-deficient cells, whereas STAT1 activation induced by IFN-gamma is prolonged. Microarray analysis shows that the pattern of gene expression induced by IL-6 in Socs3-deficient livers mimics that induced by IFN-gamma. Our data indicate that SOCS3 and SOCS1 have reciprocal functions in IL-6 and IFN-gamma regulation and imply that SOCS3 has a role in preventing IFN-gamma-like responses in cells stimulated by IL-6.
Nature. 2003 Aug 14;424(6950):743-8.
Comment in: Nature. 2003 Aug 14;424(6950):736-7.
Identification of Lps2 as a key transducer of MyD88-independent TIR signalling.
Hoebe K, Du X, Georgel P, Janssen E, Tabeta K, Kim SO, Goode J, Lin P, Mann N, Mudd S, Crozat K, Sovath S, Han J, Beutler B.
Department of Immunology, IMM-31, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
Nat Immunol. 2003 Jun;4(6):557-64.
Comment in: Nat Immunol. 2003 Jun;4(6):509-10.
NKG2D-DAP10 triggers human NK cell-mediated killing via a Syk-independent regulatory pathway.
Billadeau DD, Upshaw JL, Schoon RA, Dick CJ, Leibson PJ.
Division of Oncology Research, Mayo Graduate and Medical Schools, Mayo Clinic, Rochester, Minnesota 55905, USA.
The immune recognition receptor complex NKG2D-DAP10 on natural killer cells is stimulated by specific ligands carried on virus-infected and malignant cells. Because DAP10 does not have an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic tail, its ability to trigger killing has been debated. Here we show that a crucial Tyr-Ile-Asn-Met amino acid motif in the cytoplasmic tail of DAP10 couples receptor stimulation to the downstream activation of phosphatidylinositol 3-kinase, Vav1, Rho family GTPases and phospholipase C. Unlike that of ITAM-containing receptors, the activation of NKG2D-DAP10 proceeds independently of Syk family protein tyrosine kinases. Yet the signals initiated by NKG2D-DAP10 are fully capable of inducing killing. Our findings identify a previously unknown mechanism by which receptor complexes that lack ITAM motifs can trigger lymphocyte activation.
J Immunol. 2003 Sep 1;171(5):2571-80.
CD1d-restricted NKT cells express a chemokine receptor profile indicative of Th1-type inflammatory
homing cells.
Thomas SY, Hou R, Boyson JE, Means TK, Hess C, Olson DP, Strominger JL, Brenner MB, Gumperz JE, Wilson SB, Luster AD.
Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital, Harvard Medical School, 13th Street, Charlestown, MA 02129, USA.
CD1d-restricted T cells (NKT cells) are innate memory cells activated by lipid Ags and play important roles in the initiation and regulation of the immune response. However, little is known about the trafficking patterns of these cells or the tissue compartment in which they exert their regulatory activity. In this study, we determined the chemokine receptor profile expressed by CD1d-restricted T cells found in the peripheral blood of healthy volunteers as well as CD1d-restricted T cell clones. CD1d-restricted T cells were identified by Abs recognizing the invariant Valpha24 TCR rearrangement or by binding to CD1d-Fc fusion tetramers loaded with alpha-GalCer. CD1d-restricted T cells in the peripheral blood and CD1d-restricted T cell clones expressed high levels of CXCR3, CCR5, and CCR6; intermediate levels of CXCR4 and CXCR6; and low levels of CXCR1, CCR1, CCR2, and CX(3)CR1, a receptor pattern often associated with tissue-infiltrating effector Th1 cells and CD8+ T cells. Very few of these cells expressed the lymphoid-homing receptors CCR7 or CXCR5. CCR4 was expressed predominantly on CD4+, but not on double-negative CD1d-restricted T cells, which may indicate differential trafficking patterns for these two functionally distinct subsets. CD1d-restricted T cell clones responded to chemokine ligands for CXCR1/2, CXCR3, CXCR4, CXCR6, CCR4, and CCR5 in calcium flux and/or chemotaxis assays. These data indicate that CD1d-restricted T cells express a chemokine receptor profile most similar to Th1 inflammatory homing cells and suggest that these cells perform their function in peripheral tissue sites rather than in secondary lymphoid organs.
Essential role of NKT cells producing IL-4 and IL-13 in the development of allergen-induced airway hyperreactivity.
Akbari O, Stock P, Meyer E, Kronenberg M, Sidobre S, Nakayama T, Taniguchi M, Grusby MJ, DeKruyff RH, Umetsu DT.
Division of Immunology and Allergy, Department of Pediatrics, Stanford University, Stanford, California,
USA.
Using natural killer T (NKT) cell-deficient mice, we show here that allergen-induced airway hyperreactivity (AHR), a cardinal feature of asthma, does not develop in the absence of V(alpha)14i NKT cells. The failure of NKT cell-deficient mice to develop AHR is not due to an inability of these mice to produce type 2 T-helper (Th2) responses because NKT cell-deficient mice that are immunized subcutaneously at non-mucosal sites produce normal Th2-biased responses. The failure to develop AHR can be reversed by the adoptive transfer of tetramer-purified NKT cells producing interleukin (IL)-4 and IL-13 to Ja281(-/-) mice, which lack the invariant T-cell receptor (TCR) of NKT cells, or by the administration to Cd1d(-/-) mice of recombinant IL-13, which directly affects airway smooth muscle cells. Thus, pulmonary V(alpha)14i NKT cells crucially regulate the development of asthma and Th2-biased respiratory immunity against nominal exogenous antigens. Therapies that target V(alpha)14i NKT cells may be clinically effective in limiting the development of AHR and asthma.
A prion protein epitope selective for the pathologically misfolded conformation.
Paramithiotis E, Pinard M, Lawton T, LaBoissiere S, Leathers VL, Zou WQ, Estey LA, Lamontagne J, Lehto MT, Kondejewski LH, Francoeur GP, Papadopoulos M, Haghighat A, Spatz SJ, Head M, Will R, Ironside J, O'Rourke K, Tonelli Q, Ledebur HC, Chakrabartty A, Cashman NR.
Caprion Pharmaceuticals Inc., 7150 Alexander-Fleming, St-Laurent, Quebec H4S 2C8, Canada.
Conformational conversion of proteins in disease is likely to be accompanied by molecular surface exposure of previously sequestered amino-acid side chains. We found that induction of beta-sheet structures in recombinant prion proteins is associated with increased solvent accessibility of tyrosine. Antibodies directed against the prion protein repeat motif, tyrosine-tyrosine-arginine, recognize the pathological isoform of the prion protein but not the normal cellular isoform, as assessed by immunoprecipitation, plate capture immunoassay and flow cytometry. Antibody binding to the pathological epitope is saturable and specific, and can be created in vitro by partial denaturation of normal brain prion protein. Conformation-selective exposure of Tyr-Tyr-Arg provides a probe for the distribution and structure of pathologically misfolded prion protein, and may lead to new diagnostics and therapeutics for prion diseases.
Immunity. 2003 May;18(5):605-17.
Characterization of dendritic cells that induce tolerance and T regulatory 1 cell differentiation in vivo.
Wakkach A, Fournier N, Brun V, Breittmayer JP, Cottrez F, Groux H.
TxCell, Bat. ARC, Route de Street Antoine de Ginestiere, 06200 Nice, France.
Active suppression is mediated by a subpopulation of CD4(+) T cells that prevents autoimmunity. However, the mechanisms involved in their differentiation in vivo are currently under intensive research. Here we show that in vitro culture of bone marrow cells in the presence of IL-10 induces the differentiation of a distinct subset of dendritic cells with a specific expression of CD45RB. These CD11c(low)CD45RB(high) DCs are present in the spleen and lymph nodes of normal mice and are significantly enriched in the spleen of IL-10 Tg mice. These natural or in vitro-derived DCs display plasmacytoid morphology and an immature-like phenotype, and secrete high levels of IL-10 after activation. OVA peptide-pulsed CD11c(low)CD45RB(high) DCs specifically induce tolerance through the differentiation of Tr1 cells in vitro and in vivo. Our findings identify a natural DC subset that induces the differentiation of Tr1 cells and suggest their therapeutic use.
Nature. 2003 Jul 17;424(6946):324-8.
Viral infection switches non-plasmacytoid dendritic cells into high interferon producers.
Diebold SS, Montoya M, Unger H, Alexopoulou L, Roy P, Haswell LE, Al-Shamkhani A, Flavell R, Borrow P, Reis e Sousa C.
Immunobiology Laboratory, Cancer Research UK, London Research Institute, London WC2A 3PX, UK.
Type I interferons (IFN-I) are important cytokines linking innate and adaptive immunity. Plasmacytoid dendritic cells make high levels of IFN-I in response to viral infection and are thought to be the major source of the cytokines in vivo. Here, we show that conventional non-plasmacytoid dendritic cells taken from mice infected with a dendritic-cell-tropic strain of lymphocytic choriomeningitis virus make similarly high levels of IFN-I on subsequent culture. Similarly, non-plasmacytoid dendritic cells secrete high levels of IFN-I in response to double-stranded RNA (dsRNA), a major viral signature, when the latter is introduced into the cytoplasm to mimic direct viral infection. This response is partially dependent on the cytosolic dsRNA-binding enzyme protein kinase R and does not require signalling through toll-like receptor (TLR) 3, a surface receptor for dsRNA. Furthermore, we show that sequestration of dsRNA by viral NS1 (refs 6, 7) explains the inability of conventional dendritic cells to produce IFN-I on infection with influenza. Our results suggest that multiple dendritic cell types, not just plasmacytoid cells, can act as specialized interferon-producing cells in certain viral infections, and reveal the existence of a TLR-independent pathway for dendritic cell activation that can be the target of viral interference.
J Immunol. 2003 Sep 1;171(5):2524-31.
IFN-gamma-producing gammadelta T cells help control murine West Nile virus infection.
Wang T, Scully E, Yin Z, Kim JH, Wang S, Yan J, Mamula M, Anderson JF, Craft J, Fikrig E.
Department of Internal Medicine, Section of Rheumatology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06520, USA.
West Nile (WN) virus causes fatal meningoencephalitis in laboratory mice, thereby partially mimicking human disease. Using this model, we have demonstrated that mice deficient in gammadelta T cells are more susceptible to WN virus infection. TCRdelta(-/-) mice have elevated viral loads and greater dissemination of the pathogen to the CNS. In wild-type mice, gammadelta T cells expanded significantly during WN virus infection, produced IFN-gamma in ex vivo assays, and enhanced perforin expression by splenic T cells. Adoptive transfer of gammadelta T cells to TCRdelta(-/-) mice reduced the susceptibility of these mice to WN virus, and this effect was primarily due to IFN-gamma-producing gammadelta T cells. These data demonstrate a distinct role for gammadelta T cells in the control of and prevention of mortality from murine WN virus infection.
Nature. 2003 Aug 7;424(6949):681-4.
Comment in: Nature. 2003 Aug 7;424(6949):602.
Accelerated vaccination for Ebola virus haemorrhagic fever in non-human primates.
Sullivan NJ, Geisbert TW, Geisbert JB, Xu L, Yang ZY, Roederer M, Koup RA, Jahrling PB, Nabel GJ.
Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bldg. 40, Room 4502, MSC 3005, 40 Convent Drive, Bethesda, Maryland 20892-3005, USA.
Containment of highly lethal Ebola virus outbreaks poses a serious public health challenge. Although an experimental vaccine has successfully protected non-human primates against disease, more than six months was required to complete the immunizations, making it impractical to limit an acute epidemic. Here, we report the development of accelerated vaccination against Ebola virus in non-human primates. The antibody response to immunization with an adenoviral (ADV) vector encoding the Ebola glycoprotein (GP) was induced more rapidly than with DNA priming and ADV boosting, but it was of lower magnitude. To determine whether this earlier immune response could nonetheless protect against disease, cynomolgus macaques were challenged with Ebola virus after vaccination with ADV-GP and nucleoprotein (NP) vectors. Protection was highly effective and correlated with the generation of Ebola-specific CD8(+) T-cell and antibody responses. Even when animals were immunized once with ADV-GP/NP and challenged 28 days later, they remained resistant to challenge with either low or high doses of virus. This accelerated vaccine provides an intervention that may help to limit the epidemic spread of Ebola, and is applicable to other viruses.
Journal of Virology, September 2003, p. 10078-10087, Vol. 77, No. 18
Enhanced Mucosal Immunoglobulin A Response of Intranasal Adenoviral Vector Human Immunodeficiency Virus Vaccine and Localization in the Central Nervous System
Franck Lemiale,1 Wing-pui Kong,1 Levent M. Akyürek,2, Xu Ling,1 Yue Huang,1 Bimal K. Chakrabarti,1 Michael Eckhaus,3 and Gary J. Nabel1*
Vaccine Research Center, NIAID,1 Vascular Biology Branch, NHLBI, National Institutes of Health,2 Pathology Section, Office of Research Services, Bethesda, Maryland 208923
Replication-defective adenovirus (ADV) vectors represent a promising potential platform for the development of a vaccine for AIDS. Although this vector is typically administered intramuscularly, it would be desirable to induce mucosal immunity by delivery through alternative routes. In this study, the immune response and biodistribution of ADV vectors delivered by different routes were evaluated. ADV vectors expressing human immunodeficiency virus type 1 (HIV-1) Gag, Pol, and Env were delivered intramuscularly or intranasally into mice. Intranasal immunization induced greater HIV-specific immunoglobulin A (IgA) responses in mucosal secretions and sera than in animals with intramuscular injection, which showed stronger systemic cellular and IgG responses. Administration of the vaccine through an intranasal route failed to overcome prior ADV immunity. Animals exposed to ADV prior to vaccination displayed substantially reduced cellular and humoral immune responses to HIV antigens in both groups, though the reduction was greater in animals immunized intranasally. This inhibition was partially overcome by priming with a DNA expression vector expressing HIV-1 Gag, Pol, and Env before boosting with the viral vector. Biodistribution of recombinant adenovirus (rADV) vectors administered intranasally revealed infection of the central nervous system, specifically in the olfactory bulb, possibly via retrograde transport by olfactory neurons in the nasal epithelium, which may limit the utility of this route of delivery of ADV vector-based vaccines.