501
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Baba N, Samson S, Bourdet-Sicard R, Rubio M, Sarfati M. Commensal bacteria trigger a full dendritic cell maturation program that promotes the expansion of non-Tr1 suppressor T cells. J Leukoc Biol 2008; 84:468-76. [PMID: 18511576 DOI: 10.1189/jlb.0108017] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Dendritic cells (DCs) orchestrate the immune response establishing immunity versus tolerance. These two opposite functions may be dictated by DC maturation status with maturity linked to immunogenicity. DCs directly interact with trillions of noninvasive intestinal bacteria in vivo, a process that contributes to gut homeostasis. We here evaluated the maturation program elicited in human DCs by direct exposure to commensal-related bacteria (CB) in the absence of inflammatory signals. We showed that eight gram(+) and gram(-) CB strains up-regulated costimulatory molecule expression in DCs and provoked a chemokine receptor switch similar to that activated by gram(+) pathogens. CB strains may be classified into three groups according to DC cytokine release: high IL-12 and low IL-10; low IL-12 and high IL-10; and low IL-12 and IL-10. All CB-treated DCs produced IL-1beta and IL-6 and almost no TGF-beta. Yet, CB instructed DCs to convert naive CD4+ T cells into hyporesponsive T cells that secreted low or no IFN-gamma, IL-10, and IL-17 and instead, displayed suppressor function. These data demonstrate that phenotypic DC maturation combined to an appropriate cytokine profile is insufficient to warrant Th1, IL-10-secreting T regulatory Type 1 (Tr1), or Th17 polarization. We propose that commensal flora and as such, probiotics manipulate DCs by a yet-unidentified pathway to enforce gut tolerance.
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Affiliation(s)
- Nobuyasu Baba
- Immunoregulation Laboratory, Centre Hospitalier de l'Université de Montréal Research Center, University of Montréal, Québec, Canada
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502
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Tournier JN, Mohamadzadeh M. Microenvironmental impact on lung cell homeostasis and immunity during infection. Expert Rev Vaccines 2008; 7:457-66. [PMID: 18444892 DOI: 10.1586/14760584.7.4.457] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The lung is a vital organ devoted mainly to gas exchange with an external environment that may be contaminated with various life-threatening pathogens and inert particles. Lung immunity must be permanently balanced between costimulatory and coinhibitory signals, thus controlling potential pathogens while avoiding detrimental inflammation. The lung harbors macrophages and dendritic cells (myeloid and plasmacytoid), which orchestrate the primary defense against microbial invaders. During an infection involving host-microbial synapses, microbes either escape by using host cell physiology or are eliminated by a robust immune response. We thus focus on the dynamics of such cellular interactions within the lung and stress the critical role played by airway epithelial cells in modulating immunity.
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Affiliation(s)
- Jean-Nicolas Tournier
- Centre de Recherches du Service de Santédes Armées, Unité Interactions Hôte-Pathogéne, La Tronche, France.
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503
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Abstract
Important developments in the design of recombinant lactic acid bacteria (LAB) as mucosal carriers for a range of health-beneficial compounds, such as antigens, allergens, immune modulators, antimicrobial and trefoil peptides, single-chain antibodies and a few enzymes, have taken place in the past decade. The different approaches, strategies and proof-of-concept studies that have been conducted in animal models are reviewed in this article. The rationale for the use of lactic acid bacteria as mucosal delivery vehicles and key aspects of their interaction with the host mucosal surfaces are discussed. An overview of the progress in the field of LAB-based mucosal vaccines and a discussion of protection studies that have been conducted in rodents, mainly by intranasal and intragastric immunization, are provided. The latest developments in the use of LAB as vechicles for DNA vaccination are described. Studies that deal with successful delivery of cytokines or trefoil peptides to treat experimental colitis in rodents are reviewed. Notably, the first Phase I trial has been conducted with patients that suffer from inflammatory bowel disease using safe biologically contained recombinant lactococci that secrete human interleukin-10. Efforts to induce oral tolerance and develop preventive strategies against type I allergies using LAB are highlighted. Anti-infective strategies that are based on the delivery of microbicidal peptides are discussed, with a special emphasis on the prevention of HIV-1 infection. The concluding section captures the key learning points in the field, identifies major questions that remain to be answered and highlights challenges for the future.
The development of lactic acid bacteria as delivery vehicles for therapeutics, anti-infectives and vaccines at mucosa is discussed in this Review. Engineered LAB could be deployed to treat conditions such as allergy and inflammatory bowel disease, and might also be adopted in the fight against pathogens, including HIV-1 infection. Studies of lactic acid bacteria (LAB) as delivery vehicles have focused mainly on the development of mucosal vaccines, with much effort being devoted to the generation of genetic tools for antigen expression in different bacterial locations. Subsequently, interleukins have been co-expressed with antigens in LAB to enhance the immune response that is raised against the antigen. LAB have also been used as a delivery system for a range of molecules that have different applications, including anti-infectives, therapies for allergic diseases and therapies for gastrointestinal diseases. Now that the first human trial with a Lactococcus strain that expresses recombinant interleukin-10 has been completed, we discuss what we have learnt, what we do not yet understand and what the future holds for therapy and prophylaxis with LAB.
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504
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Fagarasan S. Evolution, development, mechanism and function of IgA in the gut. Curr Opin Immunol 2008; 20:170-7. [PMID: 18456485 DOI: 10.1016/j.coi.2008.04.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 04/03/2008] [Accepted: 04/07/2008] [Indexed: 12/20/2022]
Abstract
Since its discovery as the most abundant Ig produced at mucosal surfaces, IgA has been the subject of continuous studies. The concepts emerged were that the precursors for IgA plasma cells are efficiently generated in follicular organized structures in the gut with the help of CD4 T cells and that secretory IgA provides protection against mucosal pathogens. Novel conceptual advances have been made in the past few years in describing new sites, mechanisms and functions of mucosal IgA synthesis.
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Affiliation(s)
- Sidonia Fagarasan
- Laboratory for Mucosal Immunity, RIKEN Research Center for Allergy and Immunology, 230-0045 Tsurumi, Yokohama, Japan.
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505
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Germain RN, Bajénoff M, Castellino F, Chieppa M, Egen JG, Huang AYC, Ishii M, Koo LY, Qi H. Making friends in out-of-the-way places: how cells of the immune system get together and how they conduct their business as revealed by intravital imaging. Immunol Rev 2008; 221:163-81. [PMID: 18275481 DOI: 10.1111/j.1600-065x.2008.00591.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
A central characteristic of the immune system is the constantly changing location of most of its constituent cells. Lymphoid and myeloid cells circulate in the blood, and subsets of these cells enter, move, and interact within, then leave organized lymphoid tissues. When inflammation is present, various hematopoietic cells also exit the vasculature and migrate within non-lymphoid tissues, where they carry out effector functions that support host defense or result in autoimmune pathology. Effective innate and adaptive immune responses involve not only the action of these individual cells but also productive communication among them, often requiring direct membrane contact between rare antigen-specific or antigen-bearing cells. Here, we describe our ongoing studies using two-photon intravital microscopy to probe the in situ behavior of the cells of the immune system and their interactions with non-hematopoietic stromal elements. We emphasize the importance of non-random cell migration within lymphoid tissues and detail newly established mechanisms of traffic control that operate at multiple organizational scales to facilitate critical cell contacts. We also describe how the methods we have developed for imaging within lymphoid sites are being applied to other tissues and organs, revealing dynamic details of host-pathogen interactions previously inaccessible to direct observation.
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Affiliation(s)
- Ronald N Germain
- Laboratory of Immunology, Lymphocyte Biology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1892, USA.
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506
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Cavanagh LL, Weninger W. Dendritic cell behaviour
in vivo
: lessons learned from intravital two‐photon microscopy. Immunol Cell Biol 2008; 86:428-38. [DOI: 10.1038/icb.2008.25] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Lois L Cavanagh
- Immune Imaging Program, Centenary Institute of Cancer Medicine and Cell BiologyNewtownNew South WalesAustralia
| | - Wolfgang Weninger
- Immune Imaging Program, Centenary Institute of Cancer Medicine and Cell BiologyNewtownNew South WalesAustralia
- Discipline of Dermatology, University of SydneySydneyNew South WalesAustralia
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507
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Hammad H, Lambrecht BN. Dendritic cells and epithelial cells: linking innate and adaptive immunity in asthma. Nat Rev Immunol 2008; 8:193-204. [PMID: 18301423 DOI: 10.1038/nri2275] [Citation(s) in RCA: 445] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Dendritic cells (DCs) are generally held responsible for initiating and maintaining allergic T helper 2 (T(H)2)-cell responses to inhaled allergens in asthma. Although the epithelium was initially considered to function solely as a physical barrier, it is now seen as a central player in the T(H)2-cell sensitization process by influencing the function of DCs. Clinically relevant allergens, as well as known environmental and genetic risk factors for allergy and asthma, often interfere directly or indirectly with the innate immune functions of airway epithelial cells and DCs. A better understanding of these interactions, ascertained from human and animal studies, might lead to better prevention and treatment of asthma.
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Affiliation(s)
- Hamida Hammad
- Department of Respiratory Diseases, Laboratory of Immunoregulation and Mucosal Immunology, University Hospital Ghent, Belgium
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508
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Cario E. Therapeutic impact of toll-like receptors on inflammatory bowel diseases: a multiple-edged sword. Inflamm Bowel Dis 2008; 14:411-21. [PMID: 17941072 DOI: 10.1002/ibd.20294] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Recent studies have begun to define the mechanisms through which Toll-like receptors (TLRs) regulate intestinal homeostasis in health and disease. Current therapies for inflammatory bowel diseases (IBDs) mostly aim at interrupting the inflammatory cascade through agents that regulate TH1 or TH2 cytokine responses. As recognition grows for TLR dysfunction to play a role in IBD pathogenesis, TLRs could provide another valid interventional target for novel therapy development. However, seemingly contradictory results from studying different murine models of colitis have so far confounded whether therapeutically useful modulation of TLRs is best accomplished by activating, inhibiting, or rather a combination of both at different stages of mucosal disease. This review evaluates potential strategies as well as their rationale and future prospects.
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Affiliation(s)
- Elke Cario
- Division of Gastroenterology & Hepatology, University Hospital of Essen, University of Duisburg-Essen, Institutsgruppe I, Virchowstrasse 171, Essen, Germany.
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509
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Damaskos D, Kolios G. Probiotics and prebiotics in inflammatory bowel disease: microflora 'on the scope'. Br J Clin Pharmacol 2008; 65:453-67. [PMID: 18279467 DOI: 10.1111/j.1365-2125.2008.03096.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The intestinal microflora is a large bacterial community that colonizes the gut, with a metabolic activity equal to an organ and various functions that affect the physiology and pathology of the host's mucosal immune system. Intestinal bacteria are useful in promotion of human health, but certain components of microflora, in genetically susceptible individuals, contribute to various pathological disorders, including inflammatory bowel disease. Clinical and experimental observations indicate an imbalance in protective and harmful microflora components in these disorders. Manipulation of gut flora to enhance its protective and beneficial role represents a promising field of new therapeutic strategies of inflammatory bowel disease. In this review, we discuss the implication of gut flora in the intestinal inflammation that justifies the role of probiotics and prebiotics in the prevention and treatment of inflammatory bowel disease and we address the evidence for therapeutic benefits from their use in experimental models of colitis and clinical trials.
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Affiliation(s)
- Dimitrios Damaskos
- Second Department of Surgery, General Hospital of Nikea, Piraeus, Greece [corrected]
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510
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Hapfelmeier S, Müller AJ, Stecher B, Kaiser P, Barthel M, Endt K, Eberhard M, Robbiani R, Jacobi CA, Heikenwalder M, Kirschning C, Jung S, Stallmach T, Kremer M, Hardt WD. Microbe sampling by mucosal dendritic cells is a discrete, MyD88-independent step in DeltainvG S. Typhimurium colitis. ACTA ACUST UNITED AC 2008; 205:437-50. [PMID: 18268033 PMCID: PMC2271026 DOI: 10.1084/jem.20070633] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Intestinal dendritic cells (DCs) are believed to sample and present commensal bacteria to the gut-associated immune system to maintain immune homeostasis. How antigen sampling pathways handle intestinal pathogens remains elusive. We present a murine colitogenic Salmonella infection model that is highly dependent on DCs. Conditional DC depletion experiments revealed that intestinal virulence of S. Typhimurium SL1344 ΔinvG mutant lacking a functional type 3 secretion system-1 (ΔinvG)critically required DCs for invasion across the epithelium. The DC-dependency was limited to the early phase of infection when bacteria colocalized with CD11c+CX3CR1+ mucosal DCs. At later stages, the bacteria became associated with other (CD11c−CX3CR1−) lamina propria cells, DC depletion no longer attenuated the pathology, and a MyD88-dependent mucosal inflammation was initiated. Using bone marrow chimeric mice, we showed that the MyD88 signaling within hematopoietic cells, which are distinct from DCs, was required and sufficient for induction of the colitis. Moreover, MyD88-deficient DCs supported transepithelial uptake of the bacteria and the induction of MyD88-dependent colitis. These results establish that pathogen sampling by DCs is a discrete, and MyD88-independent, step during the initiation of a mucosal innate immune response to bacterial infection in vivo.
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511
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Turer EE, Tavares RM, Mortier E, Hitotsumatsu O, Advincula R, Lee B, Shifrin N, Malynn BA, Ma A. Homeostatic MyD88-dependent signals cause lethal inflamMation in the absence of A20. ACTA ACUST UNITED AC 2008; 205:451-64. [PMID: 18268035 PMCID: PMC2271029 DOI: 10.1084/jem.20071108] [Citation(s) in RCA: 225] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Toll-like receptors (TLRs) on host cells are chronically engaged by microbial ligands during homeostatic conditions. These signals do not cause inflammatory immune responses in unperturbed mice, even though they drive innate and adaptive immune responses when combating microbial infections. A20 is a ubiquitin-modifying enzyme that restricts exogenous TLR-induced signals. We show that MyD88-dependent TLR signals drive the spontaneous T cell and myeloid cell activation, cachexia, and premature lethality seen in A20-deficient mice. We have used broad spectrum antibiotics to demonstrate that these constitutive TLR signals are driven by commensal intestinal flora. A20 restricts TLR signals by restricting ubiquitylation of the E3 ligase tumor necrosis factor receptor–associated factor 6. These results reveal both the severe proinflammatory pathophysiology that can arise from homeostatic TLR signals as well as the critical role of A20 in restricting these signals in vivo. In addition, A20 restricts MyD88-independent TLR signals by inhibiting Toll/interleukin 1 receptor domain–containing adaptor inducing interferon (IFN) β–dependent nuclear factor κB signals but not IFN response factor 3 signaling. These findings provide novel insights into how physiological TLR signals are regulated.
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Affiliation(s)
- Emre E Turer
- Gastrointestinal Division, Department of Medicine, Biomedical Sciences Program, University of California, San Francisco, San Francisco, CA 94143, USA
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512
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Martinoli C, Chiavelli A, Rescigno M. Entry route of Salmonella typhimurium directs the type of induced immune response. Immunity 2008; 27:975-84. [PMID: 18083577 DOI: 10.1016/j.immuni.2007.10.011] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 10/12/2007] [Accepted: 10/30/2007] [Indexed: 12/30/2022]
Abstract
Secretory immunoglobulin A (SIgA) represents a first line of defense against mucosal pathogens by limiting their entrance. By using different strains of Salmonella typhimurium that target the two mechanisms of bacterial entry (microfold cell [M cell]- or dendritic cell-mediated), we demonstrated here that the distribution of bacteria after oral infection directed the type of induced immune response. M cell-penetrating invasive, but not noninvasive, S. typhimurium was found in large numbers in Peyer's patches (PPs), leading to the activation of immune cells and the release of fecal IgA. In contrast, both strains of bacteria were equally capable of reaching the mesenteric lymph node and the spleen and inducing IgG responses. These data suggest that PPs are absolutely required for the initiation of an IgA response to Salmonella, whereas they are dispensable for a systemic response. This compartmentalization could allow the fast generation of both mucosal and systemic acquired immunity to pathogens.
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Affiliation(s)
- Chiara Martinoli
- Department of Experimental Oncology, European Institute of Oncology, I-20124 Milan, Italy
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513
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Dynamic interactions between bacteria and immune cells leading to intestinal IgA synthesis. Semin Immunol 2008; 20:59-66. [DOI: 10.1016/j.smim.2007.12.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Accepted: 12/06/2007] [Indexed: 12/30/2022]
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514
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515
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Abstract
The mammalian immune system discriminates among microbes, inactivating pathogens while tolerating colonization by commensal organisms. Calibrating immune responses to microbes on this basis, however, is complex, as microbial virulence is often context dependent, being influenced by the host's immune status and the microbial milieu. Many microbial pathogens infecting immunocompromised hosts, for example, are innocuous in immune-competent individuals, and other microbes cause disease only when the commensal flora is compromised by antibiotic therapy. Recent studies have begun to reveal how the immune system tips the balance in favor of some microbes, allowing commensals to persist on mucosal surfaces while eliminating disease-causing pathogens.
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Affiliation(s)
- Eric G Pamer
- Infectious Diseases Service, Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
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516
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517
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Bajénoff M, Germain RN. Seeing is believing: a focus on the contribution of microscopic imaging to our understanding of immune system function. Eur J Immunol 2008; 37 Suppl 1:S18-33. [PMID: 17972341 DOI: 10.1002/eji.200737663] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Many cells of the immune system do not occupy fixed tissue locations, but circulate in the blood, traffic through the lymph, and migrate within organized lymphoid organs and periphery tissues. Rare antigen-specific lymphocytes must find one another for productive adaptive immune responses and the different phases of cell-mediated and humoral immune response development take place in distinct sites. This historical feature examines how we have reached our current understanding of these aspects of immune system function. It emphasizes the critical role of ever-improving imaging techniques in determining where immune cells reside and interact and stresses the key past contribution of sequential static immunohistochemical analysis using monoclonal reagents. In combination with genetic studies, these imaging experiments resulted in our current paradigm that views activation-dependent changes in chemokine sensitivity as central to effective cell co-operation. We also highlight the very recent application of two-photon imaging to the direct observation of immune cell dynamics in a natural tissue environment, noting how the application of this technology has reinforced some existing ideas and is changing other long-held views. We conclude with some speculations about the opportunities for further advances using ever more powerful imaging methods.
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Affiliation(s)
- Marc Bajénoff
- Lymphocyte Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1892, USA
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518
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Muixí L, Alvarez I, Jaraquemada D. Peptides presented in vivo by HLA-DR in thyroid autoimmunity. Adv Immunol 2008; 99:165-209. [PMID: 19117535 DOI: 10.1016/s0065-2776(08)00606-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The association of the major histocompatibility complex (MHC) genes with autoimmune diseases together with the ectopic expression of class II molecules by epithelial cells of the target tissue gives to these molecules a central role in the pathogenesis of the disease, in its regulation and in the persistence of the immune response in situ. HLA-DR molecules expressed by thyroid follicular cells in thyroid autoimmune diseases are compact molecules stably associated with peptides. The nature of these peptides is of vital importance in the understanding of the disease, since these MHC-II-peptide complexes are going to be recognized by both effector and regulatory T cells in situ. In this chapter, we review the current state of the analysis of naturally processed peptides presented by MHC class II molecules in the context of autoimmunity and we discuss our data of natural HLA-DR ligands eluted from Graves' disease affected thyroid glands, from where autoantigen-derived peptides have been identified.
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Affiliation(s)
- Laia Muixí
- Immunology Unit, Institut de Biotechnologia i Biomedicina, Universitat Autònoma de Barcelona, Campus de Bellaterra, Barcelona, Spain
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519
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Abstract
INTRODUCTION/BACKGROUND Inflammatory bowel disease (IBD) results from complex interactions between: host genome, immune system, mucosa, bacteria, and environment. SOURCES OF DATA Review of PubMed database using search terms 'bacteria and inflammatory bowel disease' and 'genetics and inflammatory bowel disease'. PubMed 'related reference' feature and references from retrieved articles were examined. AREAS OF AGREEMENT IBD results from interaction between the microbiota of the gut and the immune system. Key gene defects associated with IBD are involved in bacterial recognition and processing. The environment at least modifies and may determine pathogenesis. AREAS OF CONTROVERSY It has been disputed whether the primary defect in IBD is immunological or bacterial, and which bacteria are key. GROWING POINTS/AREAS FOR RESEARCH: 'M cells', the specialized epithelial cells that overlie Peyer's patches, are a major interface between gut bacteria and the immune system. Improved understanding is needed of the bacteria involved in IBD pathogenesis, their genotypes and phenotypes, their portal of entry and their mechanism for escaping attack from the immune system. Bacterial ligands involved in bacteria-epithelial adhesion are emerging, and molecular techniques are rapidly increasing our knowledge of the human intestinal microbiota.
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Affiliation(s)
- Paul Knight
- School of Clinical Sciences, University of Liverpool, Nuffield Building, Crown Street, Liverpool L693BX, UK
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520
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Cholera toxin, E. coli heat-labile toxin, and non-toxic derivatives induce dendritic cell migration into the follicle-associated epithelium of Peyer's patches. Mucosal Immunol 2008; 1:59-67. [PMID: 19079161 PMCID: PMC2614317 DOI: 10.1038/mi.2007.7] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The follicle-associated epithelium (FAE) of Peyer's patches (PPs) transports antigens and microorganisms into mucosal lymphoid tissues where they are captured by subepithelial dendritic cells (DCs). Feeding of cholera toxin (CT) induced migration of subepithelial DCs to interfollicular T-cell areas within 24 h. This study investigated short-term effects of CT, Escherichia coli heat-labile toxin, and non-toxic derivatives on DC migration. CT or CTB injected into ligated intestinal loops induced significant increase in CD11c+ DCs within the FAE within 90 min. In mice fed CT intragastrically, DC numbers in the FAE increased by 1 h, were maximal by 2 h, declined between 8 and 12 h, and were reversed by 24 h. Feeding of native LT, recombinant CTB, dibutyryl cyclic AMP, and to a lesser extent mutated CT(E29H) or mutated LT(R192G) had the same effect. Thus, both A and B subunits of enterotoxins, presumably acting through distinct signaling pathways, may promote capture of incoming antigens and pathogens by PP DCs.
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521
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Rescigno M, Mileti E. Interactions between Epithelial Cells and Dendritic Cells in Bacterial Handling. Biosci Microflora 2008. [DOI: 10.12938/bifidus.27.113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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522
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Lasker Basic Medical Research Award. Dendritic cells: versatile controllers of the immune system. Nat Med 2007; 13:1155-9. [PMID: 17917664 DOI: 10.1038/nm1643] [Citation(s) in RCA: 236] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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523
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Fritz JH, Le Bourhis L, Magalhaes JG, Philpott DJ. Innate immune recognition at the epithelial barrier drives adaptive immunity: APCs take the back seat. Trends Immunol 2007; 29:41-9. [PMID: 18054284 DOI: 10.1016/j.it.2007.10.002] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 10/29/2007] [Accepted: 10/29/2007] [Indexed: 01/07/2023]
Abstract
Innate immune recognition of microbe-associated molecular patterns by multiple families of pattern-recognition molecules such as Toll-like receptors and Nod-like receptors instructs the innate and adaptive immune system to protect the host from pathogens while also acting to establish a beneficial mutualism with commensal organisms. Although this task has been thought to be performed mainly by specialized antigen-presenting cells such as dendritic cells, recent observations point to the idea that innate immune recognition by stromal cells has important implications for the regulation of mucosal homeostasis as well as for the initiation of innate and adaptive immunity.
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Affiliation(s)
- Jörg H Fritz
- University of Toronto, Department of Immunology, Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
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524
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Garrett WS, Lord GM, Punit S, Lugo-Villarino G, Mazmanian S, Ito S, Glickman JN, Glimcher LH. Communicable ulcerative colitis induced by T-bet deficiency in the innate immune system. Cell 2007; 131:33-45. [PMID: 17923086 PMCID: PMC2169385 DOI: 10.1016/j.cell.2007.08.017] [Citation(s) in RCA: 722] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 07/09/2007] [Accepted: 08/13/2007] [Indexed: 12/12/2022]
Abstract
Inflammatory bowel disease (IBD) has been attributed to overexuberant host immunity or the emergence of harmful intestinal flora. The transcription factor T-bet orchestrates inflammatory genetic programs in both adaptive and innate immunity. We describe a profound and unexpected function for T-bet in influencing the behavior of host inflammatory activity and commensal bacteria. T-bet deficiency in the innate immune system results in spontaneous and communicable ulcerative colitis in the absence of adaptive immunity and increased susceptibility to colitis in immunologically intact hosts. T-bet controls the response of the mucosal immune system to commensal bacteria by regulating TNF-alpha production in colonic dendritic cells, critical for colonic epithelial barrier maintenance. Loss of T-bet influences bacterial populations to become colitogenic, and this colitis is communicable to genetically intact hosts. These findings reveal a novel function for T-bet as a peacekeeper of host-commensal relationships and provide new perspectives on the pathophysiology of IBD.
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Affiliation(s)
- Wendy S. Garrett
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA
- Department of Medical Oncology, Dana Farber Cancer Institute, Boston, MA
| | - Graham M. Lord
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA
- Department of Nephrology and Transplantation, King’s College, London, SE1 9RT, UK
- NIHR Biomedical Research Centre at Guy’s & St Thomas’ NHS Foundation Trust and King’s College London, UK
| | - Shivesh Punit
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA
| | | | - Sarkis Mazmanian
- Division of Biology, California Institute of Technology, Pasadena, CA
| | - Susumu Ito
- Department of Medicine, Harvard Medical School, Boston, MA
| | - Jonathan N. Glickman
- Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - Laurie H. Glimcher
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
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525
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Sabatté J, Ceballos A, Raiden S, Vermeulen M, Nahmod K, Maggini J, Salamone G, Salomón H, Amigorena S, Geffner J. Human seminal plasma abrogates the capture and transmission of human immunodeficiency virus type 1 to CD4+ T cells mediated by DC-SIGN. J Virol 2007; 81:13723-34. [PMID: 17913809 PMCID: PMC2168832 DOI: 10.1128/jvi.01079-07] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN) is expressed by dendritic cells (DCs) at mucosal surfaces and appears to play an important role in the dissemination of human immunodeficiency virus type 1 (HIV-1) infection. DC-SIGN binds HIV-1 gp120 and efficiently transmits the virus to T CD4(+) cells, which become the center of viral replication. Semen represents the main vector for HIV-1 dissemination worldwide. In the present study we show that human seminal plasma (SP), even when used at very high dilutions (1:10(4) to 1:10(5)), markedly inhibits the capture and transmission of HIV-1 to T CD4(+) cells mediated by both DCs and B-THP-1-DC-SIGN cells. In contrast, SP does not inhibit the capture of HIV-1 by DC-SIGN-negative target cells, such as the T-cell line SupT-1, monocytes, and activated peripheral blood mononuclear cells. The SP inhibitor has a high molecular mass (>100 kDa) and directly interacts with DC-SIGN-positive target cells but not with HIV-1. Moreover, the inhibitor binds to concanavalin A, suggesting that it contains high-mannose N-linked carbohydrates. Of note, using biotin-labeled SP we found that the binding of SP components to DCs was abrogated by mannan, while their interaction with B-THP-1 cells was almost completely dependent on the expression of DC-SIGN. Since epithelium integrity is often compromised after vaginal or anal intercourse, as well as in the presence of ulcerative-sexually transmitted diseases, our results support the notion that components of the SP might be able to access to the subepithelium, inhibiting the recognition of HIV-1 gp120 by DC-SIGN-positive DCs.
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Affiliation(s)
- Juan Sabatté
- National Reference Center for AIDS, Department of Microbiology, Buenos Aires University School of Medicine, Argentina
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526
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Iliev ID, Matteoli G, Rescigno M. The yin and yang of intestinal epithelial cells in controlling dendritic cell function. ACTA ACUST UNITED AC 2007; 204:2253-7. [PMID: 17893197 PMCID: PMC2118441 DOI: 10.1084/jem.20062535] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Recent work suggests that dendritic cells (DCs) in mucosal tissues are "educated" by intestinal epithelial cells (IECs) to suppress inflammation and promote immunological tolerance. After attack by pathogenic microorganisms, however, "non-educated" DCs are recruited from nearby areas, such as the dome of Peyer's patches (PPs) and the blood, to initiate inflammation and the ensuing immune response to the invader. Differential epithelial cell (EC) responses to commensals and pathogens may control these two tolorogenic and immunogenic functions of DCs.
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Affiliation(s)
- Iliyan D Iliev
- Department of Experimental Oncology, European Institute of Oncology, 20141 Milan, Italy
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527
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Denning TL, Wang YC, Patel SR, Williams IR, Pulendran B. Lamina propria macrophages and dendritic cells differentially induce regulatory and interleukin 17-producing T cell responses. Nat Immunol 2007; 8:1086-94. [PMID: 17873879 DOI: 10.1038/ni1511] [Citation(s) in RCA: 789] [Impact Index Per Article: 46.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Accepted: 08/15/2007] [Indexed: 02/07/2023]
Abstract
The intestinal immune system must elicit robust immunity against harmful pathogens but must also restrain immune responses directed against commensal microbes and dietary antigens. The mechanisms that maintain this dichotomy are poorly understood. Here we describe a population of CD11b+F4/80+CD11c- macrophages in the lamina propria that expressed several anti-inflammatory molecules, including interleukin 10 (IL-10), but little or no proinflammatory cytokines, even after stimulation with Toll-like receptor ligands. These macrophages induced, by a mechanism dependent on IL-10, retinoic acid and exogenous transforming growth factor-beta, the differentiation of Foxp3+ regulatory T cells. In contrast, lamina propria CD11b+ dendritic cells elicited IL-17 production. This IL-17 production was suppressed by lamina propria macrophages, indicating that a dynamic interaction between these subsets may influence the balance between immune activation and tolerance.
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Affiliation(s)
- Timothy L Denning
- Vaccine Research Center and Yerkes Regional Primate Research Center, Emory University, Atlanta, Georgia 30329, USA
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528
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Abstract
Recently, substantial advances in the understanding of the molecular pathogenesis of inflammatory bowel disease (IBD) have been made owing to three related lines of investigation. First, IBD has been found to be the most tractable of complex disorders for discovering susceptibility genes, and these have shown the importance of epithelial barrier function, and innate and adaptive immunity in disease pathogenesis. Second, efforts directed towards the identification of environmental factors implicate commensal bacteria (or their products), rather than conventional pathogens, as drivers of dysregulated immunity and IBD. Third, murine models, which exhibit many of the features of ulcerative colitis and seem to be bacteria-driven, have helped unravel the pathogenesis/mucosal immunopathology of IBD.
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Affiliation(s)
- R J Xavier
- Gastrointestinal Unit and Center for the Study of Inflammatory Bowel Disease, and, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA
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529
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Wick MJ. Monocyte and dendritic cell recruitment and activation during oral Salmonella infection. Immunol Lett 2007; 112:68-74. [PMID: 17720254 DOI: 10.1016/j.imlet.2007.07.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 07/13/2007] [Accepted: 07/15/2007] [Indexed: 12/24/2022]
Abstract
Immunity to bacterial infection involves the joint effort of the innate and adaptive immune systems. The innate immune response is triggered when the body senses bacterial components, such as lipopolysaccharide, that alarm the body of the invader. An array of cell types function in the innate response. These cells are rapidly recruited to the infection site and activated to optimally perform their functions. The adaptive immune response follows the innate response, and one cell type in particular, dendritic cells (DCs), are the critical link between the innate and adaptive responses. This review will summarize recent data concerning the events that occur early during oral infection with the intracellular pathogen Salmonella, with emphasis on the phagocytic cells involved in combating the infection in the gut-associated lymphoid tissues. In particular, recent findings concerning the recruitment and activation of mononuclear phagocyte populations and dendritic cell subsets will be presented after an overview of the Salmonella infection model.
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Affiliation(s)
- Mary Jo Wick
- Department of Microbiology and Immunology, Göteborg University, Box 435, S-405 30 Göteborg, Sweden.
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530
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Phipps S, Lam CE, Foster PS, Matthaei KI. The contribution of toll-like receptors to the pathogenesis of asthma. Immunol Cell Biol 2007; 85:463-70. [PMID: 17680012 DOI: 10.1038/sj.icb.7100104] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Asthma is a major disease in the westernized world and its incidence has significantly increased over the past 40 years. Our understanding of the pathogenesis of asthma remains rudimentary, and for this reason, little has been accomplished by way of targeted intervention, either at a population level (to reduce the overall prevalence) or at an individual level (to treat the cause). Instead, the management strategy currently in use relies on broad-spectrum anti-inflammatory agents, generally glucocorticoids and long-acting beta2 agonists. The recent discovery of toll-like receptors (TLRs), with their role as the initiators of the innate immune response and inflammation, suggests that modulating these receptors may be beneficial in the treatment of allergic disorders. We review here the cellular distribution of TLR in the lung and their potential contribution to the processes that promote T helper 2 (Th2) immunity and infection-induced exacerbations of allergic lung disease.
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Affiliation(s)
- Simon Phipps
- Centre for Asthma and Respiratory Diseases, School of Biomedical Sciences, University of Newcastle, David Maddison Clinical Sciences Building, Newcastle, New South Wales, Australia
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531
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Månsson LE, Melican K, Molitoris BA, Richter-Dahlfors A. Progression of bacterial infections studied in real time--novel perspectives provided by multiphoton microscopy. Cell Microbiol 2007; 9:2334-43. [PMID: 17662072 DOI: 10.1111/j.1462-5822.2007.01019.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The holy grail of infection biology is to study a pathogen within its natural infectious environment, the living host. Advances in in vivo imaging techniques have begun to introduce the possibility to visualize, in real time, infection progression within a living model. In this review we detail the current advancements and knowledge in multiphoton microscopy and how it can be related to the field of microbial infections. This technology is a new and very valuable tool for in vivo imaging, and using this technique it is possible to begin to study various microbes within their natural infectious environment - the living host.
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Affiliation(s)
- Lisa E Månsson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, S-171 77 Stockholm, Sweden
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532
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Zeuthen LH, Fink LN, Frokiaer H. Epithelial cells prime the immune response to an array of gut-derived commensals towards a tolerogenic phenotype through distinct actions of thymic stromal lymphopoietin and transforming growth factor-beta. Immunology 2007; 123:197-208. [PMID: 17655740 PMCID: PMC2433297 DOI: 10.1111/j.1365-2567.2007.02687.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Humans and other mammals coexist with a diverse array of microbes colonizing the intestine, termed the microflora. The relationship is symbiotic, with the microbes benefiting from a stable environment and nutrient supply, and the host gaining competitive exclusion of pathogens and continuously maintenance of the gut immune homeostasis. Here we report novel crosstalk mechanisms between the human enterocyte cell line, Caco2, and underlying human monocyte-derived DC in a transwell model where Gram-positive (G+) commensals prevent Toll-like receptor-4 (TLR4)-dependent Escherichia coli-induced semimaturation in a TLR2-dependent fashion. These findings add to our understanding of the hypo-responsiveness of the gut epithelium towards the microflora. Gut DC posses a more tolerogenic phenotype than conventional DC. Here we show that Caco2 spent medium (SM) induces tolerogenic DC with lower expression of maturation markers, interleukin (IL)-12p70, and tumour necrosis factor-alpha when matured with G+ and Gram-negative (G-) commensals, while IL-10 production is enhanced in DC upon encountering G+ commensals and reduced upon encountering G- bacteria. The Caco2 SM-induced tolerogenic phenotype is also seen in DC priming of naive T cells with elevated levels of transforming growth factor-beta (TGF-beta) and markedly reduced levels of bacteria-induced interferon-gamma production. Caco2 cell production of IL-8, thymic stromal lymphopoietin (TSLP) and TGF-beta increases upon microbial stimulation in a strain dependent manner. TSLP and TGF-beta co-operate in inducing the tolerogenic DC phenotype but other mediators might be involved.
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Affiliation(s)
- Louise Hjerrild Zeuthen
- BioCentrum-DTU, Nutritional Immunology Group, Center for Biological Sequence Analysis, Technical University of Denmark, Lyngby, Denmark.
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533
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Brandl K, Plitas G, Schnabl B, DeMatteo RP, Pamer EG. MyD88-mediated signals induce the bactericidal lectin RegIII gamma and protect mice against intestinal Listeria monocytogenes infection. ACTA ACUST UNITED AC 2007; 204:1891-900. [PMID: 17635956 PMCID: PMC2118673 DOI: 10.1084/jem.20070563] [Citation(s) in RCA: 303] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Listeria monocytogenes is a food-borne bacterial pathogen that causes systemic infection by traversing the intestinal mucosa. Although MyD88-mediated signals are essential for defense against systemic L. monocytogenes infection, the role of Toll-like receptor and MyD88 signaling in intestinal immunity against this pathogen has not been defined. We show that clearance of L. monocytogenes from the lumen of the distal small intestine is impaired in MyD88−/− mice. The distal ileum of wild-type (wt) mice expresses high levels of RegIIIγ, which is a bactericidal lectin that is secreted into the bowel lumen, whereas RegIIIγ expression in MyD88−/− mice is nearly undetectable. In vivo depletion of RegIIIγ from the small intestine of wt mice diminishes killing of luminal L. monocytogenes, whereas reconstitution of MyD88-deficient mice with recombinant RegIIIγ enhances intestinal bacterial clearance. Experiments with bone marrow chimeric mice reveal that MyD88-mediated signals in nonhematopoietic cells induce RegIIIγ expression in the small intestine, thereby enhancing bacterial killing. Our findings support a model of MyD88-mediated epithelial conditioning that protects the intestinal mucosa against bacterial invasion by inducing RegIIIγ.
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Affiliation(s)
- Katharina Brandl
- Infectious Diseases Service, Department of Medicine, Immunology Program, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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534
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Wilson KT, Crabtree JE. Immunology of Helicobacter pylori: insights into the failure of the immune response and perspectives on vaccine studies. Gastroenterology 2007; 133:288-308. [PMID: 17631150 DOI: 10.1053/j.gastro.2007.05.008] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 05/02/2007] [Indexed: 02/08/2023]
Abstract
Helicobacter pylori infects the stomach of half of the human population worldwide and causes chronic active gastritis, which can lead to peptic ulcer disease, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. The host immune response to the infection is ineffective, because the bacterium persists and the inflammation continues for decades. Bacterial activation of epithelial cells, dendritic cells, monocytes, macrophages, and neutrophils leads to a T helper cell 1 type of adaptive response, but this remains inadequate. The host inflammatory response has a key functional role in disrupting acid homeostasis, which impacts directly on the colonization patterns of H pylori and thus the extent of gastritis. Many potential mechanisms for the failure of the host response have been postulated, and these include apoptosis of epithelial cells and macrophages, inadequate effector functions of macrophages and dendritic cells, VacA inhibition of T-cell function, and suppressive effects of regulatory T cells. Because of the extent of the disease burden, many strategies for prophylactic or therapeutic vaccines have been investigated. The goal of enhancing the host's ability to generate protective immunity has met with some success in animal models, but the efficacy of potential vaccines in humans remains to be demonstrated. Aspects of H pylori immunopathogenesis are reviewed and perspectives on the failure of the host immune response are discussed. Understanding the mechanisms of immune evasion could lead to new opportunities for enhancing eradication and prevention of infection and associated disease.
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Affiliation(s)
- Keith T Wilson
- Division of Gastroenterology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0252, USA
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535
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Pabst O, Bernhardt G, Förster R. The impact of cell-bound antigen transport on mucosal tolerance induction. J Leukoc Biol 2007; 82:795-800. [PMID: 17565048 DOI: 10.1189/jlb.0307144] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Mucosal surfaces are exposed continuously to a flood of foreign antigens demanding a tightly controlled balance between immunity and tolerance induction. Tolerance toward food and inhaled antigens, known as oral and respiratory tolerance, respectively, evokes a body-wide nonresponsiveness against the plethora of environmental antigens. Key issues in understanding the induction of mucosal tolerance relate to the site of antigen entrance, the mechanisms of antigen transport, and the exact anatomical location where lymphocytes meet their cognate antigens. In this regard, opposing ideas have been put forward: In one scenario, antigens taken up at mucosal surfaces are considered to spread throughout the body, thus potentially evoking tolerogenic immune responses in all secondary lymphoid organs. Alternatively, tolerance induction might be confined to the draining regional lymph nodes (LN). Recent observations strongly supported the latter scenario, emphasizing the importance of regional LN and their network of afferent lymphatics in this process. In this model, air-borne and intestinal antigens are captured at mucosal sites by dendritic cells, which then migrate exclusively in a CCR7-dependent way to draining regional LN. Tolerance is then induced actively by the activation of antigen-specific T cells, which are subsequently deleted, become anergic, or alternatively, differentiate into regulatory T cells. Thus, the concept of local induction of immune responses seems to hold true for the majority of immune reactions, regardless of whether they are tolerogenic or defensive in their outcome.
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Affiliation(s)
- Oliver Pabst
- Institute of Immunology, Hannover Medical School, Carl-Neuberg Strasse 1, 30625 Hannover, Germany.
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536
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Bueno SM, González PA, Schwebach JR, Kalergis AM. T cell immunity evasion by virulent Salmonella enterica. Immunol Lett 2007; 111:14-20. [PMID: 17583359 DOI: 10.1016/j.imlet.2007.05.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 04/13/2007] [Accepted: 05/11/2007] [Indexed: 12/30/2022]
Abstract
Salmonella enterica are Gram-negative bacteria that cause systemic disease in their specific hosts. One of the recently appreciated features of Salmonella pathogenicity is the capacity of the bacteria to impair host adaptive immunity by interfering with DC function and T cell activation. It is likely that this feature of virulent Salmonella is needed to promote systemic dissemination in the host. Recent studies have suggested explanations for some of the molecular mechanisms developed by virulent Salmonella to impair DC and T cell function. Several of these mechanisms require the expression of virulence genes encoded within Salmonella pathogenicity islands. Targeted deletion of these genes diminishes Salmonella pathogenicity and leads to efficient activation of T cells by Salmonella-infected DCs. In this review, recent data that support the subversion of DC function by Salmonella as a means to evade host adaptive immunity and cause systemic infection are discussed. These new findings suggest a new pathogenesis model with DCs as key targets for Salmonella virulence factors.
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Affiliation(s)
- Susan M Bueno
- Millennium Nucleus on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Chile
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537
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Chieppa M, Rescigno M, Huang AY, Germain RN. Dynamic imaging of dendritic cell extension into the small bowel lumen in response to epithelial cell TLR engagement. J Biophys Biochem Cytol 2006. [DOI: 10.1083/jcb1756oia15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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