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Tobian AAR, Potter NS, Ramachandra L, Pai RK, Convery M, Boom WH, Harding CV. Alternate class I MHC antigen processing is inhibited by Toll-like receptor signaling pathogen-associated molecular patterns: Mycobacterium tuberculosis 19-kDa lipoprotein, CpG DNA, and lipopolysaccharide. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:1413-22. [PMID: 12874233 DOI: 10.4049/jimmunol.171.3.1413] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Pathogen-associated molecular patterns (PAMPs) signal through Toll-like receptors (TLRs) to activate immune responses, but prolonged exposure to PAMPs from Mycobacterium tuberculosis (MTB) and other pathogens inhibits class II MHC (MHC-II) expression and Ag processing, which may allow MTB to evade CD4(+) T cell immunity. Alternate class I MHC (MHC-I) processing allows macrophages to present Ags from MTB and other bacteria to CD8(+) T cells, but the effect of PAMPs on this processing pathway is unknown. In our studies, MTB and TLR-signaling PAMPs, MTB 19-kDa lipoprotein, CpG DNA, and LPS, inhibited alternate MHC-I processing of latex-conjugated Ag by IFN-gamma-activated macrophages. Inhibition was dependent on TLR-2 for MTB 19-kDa lipoprotein (but not whole MTB or the other PAMPs); inhibition was dependent on myeloid differentiation factor 88 for MTB and all of the individual PAMPs. Inhibition of MHC-II and alternate MHC-I processing was delayed, appearing after 16 h of PAMP exposure, as would occur in chronically infected macrophages. Despite inhibition of alternate MHC-I Ag processing, there was no inhibition of MHC-I expression, MHC-I-restricted presentation of exogenous peptide or conventional MHC-I processing of cytosolic Ag. MTB 19-kDa lipoprotein and other PAMPs inhibited phagosome maturation and phagosome Ag degradation in a myeloid differentiation factor 88-dependent manner; this may limit availability of peptides to bind MHC-I. By inhibiting both MHC-II and alternate MHC-I Ag processing, pathogens that establish prolonged infection of macrophages (>16 h), e.g., MTB, may immunologically silence macrophages and evade surveillance by both CD4(+) and CD8(+) T cells, promoting chronic infection.
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Affiliation(s)
- Aaron A R Tobian
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA
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Schaible UE, Winau F, Sieling PA, Fischer K, Collins HL, Hagens K, Modlin RL, Brinkmann V, Kaufmann SHE. Apoptosis facilitates antigen presentation to T lymphocytes through MHC-I and CD1 in tuberculosis. Nat Med 2003; 9:1039-46. [PMID: 12872166 DOI: 10.1038/nm906] [Citation(s) in RCA: 375] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2003] [Accepted: 07/08/2003] [Indexed: 11/10/2022]
Abstract
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.
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Affiliation(s)
- Ulrich E Schaible
- Max-Planck Institute for Infection Biology, Department of Immunology, Schumannstrasse 21-22, D-10117 Berlin, Germany.
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Sherwood ER, Lin CY, Tao W, Hartmann CA, Dujon JE, French AJ, Varma TK. Beta 2 microglobulin knockout mice are resistant to lethal intraabdominal sepsis. Am J Respir Crit Care Med 2003; 167:1641-9. [PMID: 12626348 DOI: 10.1164/rccm.200208-950oc] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
beta 2 microglobulin knockout (beta2M-/-) mice lack CD8+ T and natural killer T cells. We hypothesized that beta 2M-/- mice are resistant to lethal intraabdominal sepsis. To test this hypothesis, mortality, cytokine production, and physiologic function were assessed in beta 2M-/- mice during sepsis caused by cecal ligation and puncture (CLP). beta 2M-/- mice survived significantly longer than wild-type mice after CLP but ultimately exhibited 100% mortality. Treatment of beta 2M-/- mice with anti-asialoGM1 to deplete natural killer cells conferred greater than 70% long-term survival. Compared with wild-type mice, beta 2M-/- mice treated with anti-asialoGM1 produced decreased amounts of proinflammatory cytokines and did not exhibit hypothermia or metabolic acidosis after CLP. Adoptive transfer of CD8+ T and natural killer cells into beta 2M-/- mice treated with anti-asialoGM1 re-established CLP-induced mortality. CD8 knockout mice treated with anti-asialoGM1, which are specifically deficient in CD8+ T and natural killer cells, exhibited 40% long-term survival after CLP. Furthermore, treatment of wild-type mice with antibodies to CD8 and asialoGM1 conferred a significant survival benefit compared with wild-type mice treated with nonspecific IgG. These findings demonstrate that beta 2M-/- mice treated with anti-asialoGM1 are resistant to CLP-induced mortality and that depletion of CD8+ T and natural killer cells largely accounts for the survival benefit observed in these mice.
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Affiliation(s)
- Edward R Sherwood
- Department of Anesthesiology, University of Texas Medical Branch, Shriners Hospital for Children, Galveston, TX 77555-0591, USA.
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Urdahl KB, Liggitt D, Bevan MJ. CD8+ T cells accumulate in the lungs of Mycobacterium tuberculosis-infected Kb-/-Db-/- mice, but provide minimal protection. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:1987-94. [PMID: 12574368 DOI: 10.4049/jimmunol.170.4.1987] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recent studies have shown that MHC class I molecules play an important role in the protective immune response to Mycobacterium tuberculosis infection. Here we showed that mice deficient in MHC class Ia, but possessing MHC class Ib (K(b-/-)D(b-/-) mice), were more susceptible to aerosol infection with M. tuberculosis than control mice, but less susceptible than mice that lack both MHC class Ia and Ib (beta(2)m(-/-) mice). The susceptibility of K(b-/-)D(b-/-) mice cannot be explained by the failure of CD8(+) T cells (presumably MHC class Ib-restricted) to respond to the infection. Although CD8(+) T cells were a relatively small population in uninfected K(b-/-)D(b-/-) mice, most already expressed an activated phenotype. During infection, a large percentage of these cells further changed their cell surface phenotype, accumulated in the lungs at the site of infection, and were capable of rapidly producing IFN-gamma following TCR stimulation. Histopathologic analysis showed widespread inflammation in the lungs of K(b-/-)D(b-/-) mice, with a paucity of lymphocytic aggregates within poorly organized areas of granulomatous inflammation. A similar pattern of granuloma formation has previously been observed in other types of MHC class I-deficient mice, but not CD8alpha(-/-) mice. Thus, neither the presence of MHC class Ib molecules themselves, nor the activity of a population of nonclassical CD8(+) effector cells, fully restored the deficit caused by the absence of MHC class Ia molecules, suggesting a unique role for MHC class Ia molecules in protective immunity against M. tuberculosis.
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Affiliation(s)
- Kevin B Urdahl
- Department of Pediatrics, Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
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Abstract
The requirement for iron as a critical component for cellular processes has long been appreciated. During infection with intracellular bacteria, iron is required by both the host cell and the pathogen that inhabits the host cell. Macrophages require iron as a cofactor for the execution of important antimicrobial effector mechanisms, including the NADPH dependent oxidative burst and the production of nitrogen radicals catalysed by the inducible nitric oxide synthase. On the other side of the equation, intracellular bacteria such as Salmonella typhimurium and Mycobacterium tuberculosis have an obligate requirement for iron to support their growth and survival inside cells. This brief report summarises the background to our work on iron modulation in infections with these two organisms and highlights key observations on how modulation of host iron status disturbs the equilibrium between host and pathogen and can determine the outcome of infection.
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Affiliation(s)
- Helen L Collins
- Division of Life Sciences, Kings College London, 150 Stamford Street, London SE19NN, UK.
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Schaible UE, Collins HL, Priem F, Kaufmann SHE. Correction of the iron overload defect in beta-2-microglobulin knockout mice by lactoferrin abolishes their increased susceptibility to tuberculosis. J Exp Med 2002; 196:1507-13. [PMID: 12461085 PMCID: PMC2194267 DOI: 10.1084/jem.20020897] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
As a resident of early endosomal phagosomes, Mycobacterium tuberculosis is connected to the iron uptake system of the host macrophage. beta-2-microglobulin (beta2m) knockout (KO) mice are more susceptible to tuberculosis than wild-type mice, which is generally taken as a proof for the role of major histocompatibility complex class I (MHC-I)-restricted CD8 T cells in protection against M. tuberculosis. However, beta2m associates with a number of MHC-I-like proteins, including HFE. This protein regulates transferrin receptor mediated iron uptake and mutations in its gene cause hereditary iron overload (hemochromatosis). Accordingly, beta2m-deficient mice suffer from tissue iron overload. Here, we show that modulating the extracellular iron pool in beta2m-KO mice by lactoferrin treatment significantly reduces the burden of M. tuberculosis to numbers comparable to those observed in MHC class I-KO mice. In parallel, the generation of nitric oxide impaired in beta2m-KO mice was rescued. Conversely, iron overload in the immunocompetent host exacerbated disease. Consistent with this, iron deprivation in infected resting macrophages was detrimental for intracellular mycobacteria. Our data establish: (a) defective iron metabolism explains the increased susceptibility of beta2m-KO mice over MHC-I-KO mice, and (b) iron overload represents an exacerbating cofactor for tuberculosis.
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Affiliation(s)
- Ulrich E Schaible
- Max-Planck-Institute for Infection Biology, Schumannstrasse 21-22, D-10117 Berlin, Germany.
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Heinzel AS, Grotzke JE, Lines RA, Lewinsohn DA, McNabb AL, Streblow DN, Braud VM, Grieser HJ, Belisle JT, Lewinsohn DM. HLA-E-dependent presentation of Mtb-derived antigen to human CD8+ T cells. J Exp Med 2002; 196:1473-81. [PMID: 12461082 PMCID: PMC2194265 DOI: 10.1084/jem.20020609] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2002] [Revised: 09/11/2002] [Accepted: 10/11/2002] [Indexed: 11/24/2022] Open
Abstract
Previous studies in mice and humans have suggested an important role for CD8+ T cells in host defense to Mtb. Recently, we have described human, Mtb-specific CD8+ cells that are neither HLA-A, B, or C nor group 1 CD1 restricted, and have found that these cells comprise the dominant CD8+ T cell response in latently infected individuals. In this report, three independent methods are used to demonstrate the ability of these cells to recognize Mtb-derived antigen in the context of the monomorphic HLA-E molecule. This is the first demonstration of the ability of HLA-E to present pathogen-derived antigen. Further definition of the HLA-E specific response may aid development of an effective vaccine against tuberculosis.
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Affiliation(s)
- Amy S Heinzel
- Division of Pulmonary & Critical Care Medicine, Portland VA Medical Center, Oregon Health Sciences University, Portland, OR 97201, USA
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Affiliation(s)
- Vanja Lazarevic
- Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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John B, Rajagopal D, Pashine A, Rath S, George A, Bal V. Role of IL-12-independent and IL-12-dependent pathways in regulating generation of the IFN-gamma component of T cell responses to Salmonella typhimurium. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:2545-52. [PMID: 12193724 DOI: 10.4049/jimmunol.169.5.2545] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Clearance of facultative intracellular pathogens such as Salmonella requires IFN-gamma from CD4 T cells. Mechanisms linking intracellular pathogen recognition with induction of IFN-gamma-producing T cells are still poorly understood. We show in this study that IL-12 is not required for commitment to the IFN-gamma-producing T cell response in infection with Salmonella typhimurium, but is needed for its maintenance. The IL-12-independent signals required for commitment depend on events during the first hour of infection and are related to Ag presentation. Even transient attenuation of Ag presentation early during infection specifically abrogates the IFN-gamma component of the resulting CD4 T cell response. The IL-12 needed for maintenance is also better induced by live rather than dead bacteria in vivo, and this difference is due to specific suppression of IL-12 induction by dead bacteria. Presence of exogenous IL-4 down-modulates IL-12 production by macrophages activated in vitro. Furthermore, macrophages from IL-4-null mice secrete high levels of both IL-12 and IL-18 in response to stimulation in vivo even with dead bacteria, but this does not lead to induction of IFN-gamma-secreting T cells in response to immunization with dead S. typhimurium. Early IL-4 is contributed by triggering of CD4 NK T cells by dead, but not live, bacteria. Thus, Ag presentation-related IL-12-independent events and IL-4-sensitive IL-12-dependent events play crucial complementary roles in the generation of the IFN-gamma-committed CD4 T cell component of the immune response in Salmonella infection.
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MESH Headings
- Animals
- Antigen Presentation/drug effects
- Cells, Cultured
- Chloroquine/administration & dosage
- Histocompatibility Antigens Class I/physiology
- Injections, Intraperitoneal
- Interferon-gamma/biosynthesis
- Interleukin-12/antagonists & inhibitors
- Interleukin-12/biosynthesis
- Interleukin-12/genetics
- Interleukin-12/physiology
- Interleukin-18/biosynthesis
- Interleukin-4/deficiency
- Interleukin-4/genetics
- Interleukin-4/pharmacology
- Killer Cells, Natural/immunology
- Macrophages, Peritoneal/immunology
- Macrophages, Peritoneal/metabolism
- Macrophages, Peritoneal/microbiology
- Mice
- Mice, Knockout
- Recombinant Proteins/pharmacology
- Salmonella Infections, Animal/genetics
- Salmonella Infections, Animal/immunology
- Salmonella Vaccines/administration & dosage
- Salmonella Vaccines/immunology
- Salmonella typhimurium/drug effects
- Salmonella typhimurium/growth & development
- Salmonella typhimurium/immunology
- Signal Transduction/immunology
- T-Lymphocyte Subsets/drug effects
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/microbiology
- Vaccines, Attenuated/administration & dosage
- Vaccines, Attenuated/immunology
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Affiliation(s)
- Beena John
- National Institute of Immunology, New Delhi, India
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Abstract
Tuberculosis poses a significant threat to mankind. Multidrug-resistant strains are on the rise, and Mycobacterium tuberculosis infection is often associated with human immunodeficiency virus infection. Satisfactory control of tuberculosis can only be achieved using a highly efficacious vaccine. Tuberculosis is particularly challenging for the immune system. The intracellular location of the pathogen shields it from antibodies, and a variety of T-cell subpopulations must be activated to challenge the bacterium's resistance to antibacterial defence mechanisms. A clear understanding of the immune responses that control the pathogen will be important for achieving optimal immunity, and information provided by functional genome analysis of M. tuberculosis will be vital in the design of a future vaccine.
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Affiliation(s)
- S H Kaufmann
- Max-Planck-Institute for Infection Biology, Department of Immunology, Berlin, Germany.
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Abstract
The multifaceted dialogue between intracellular bacteria and the mammalian host continues to be an exciting issue from both the scientific and public-health viewpoint. The recent year has witnessed some particularly impressive progress in knowledge about the two major culprits affecting the health of mankind, Mycobacterium tuberculosis and Salmonella typhi - the causative agents of tuberculosis and typhoid fever.
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Affiliation(s)
- B Raupach
- Max-Planck-Institute for Infection Biology, Department of Immunology, Schumannstrasse 21-22, 10117, Berlin, Germany.
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Affiliation(s)
- H L Collins
- Department of Immunology, Max-Planck Institute for Infection Biology, Berlin, Germany.
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