RESUMEN
Treatment of post-transplant patients with immunosuppressive drugs targeting the calcineurin-nuclear factor of activated T cells (NFAT) pathway, including cyclosporine A or tacrolimus, is commonly associated with a higher incidence of opportunistic infections, such as Aspergillus fumigatus, which can lead to severe life-threatening conditions. A component of the A. fumigatus cell wall, ß-glucan, is recognized by dendritic cells (DCs) via the Dectin-1 receptor, triggering downstream signaling that leads to calcineurin-NFAT binding, NFAT translocation, and transcription of NFAT-regulated genes. Here, we address the question of whether calcineurin signaling in CD11c-expressing cells, such as DCs, has a specific role in the innate control of A. fumigatus. Impairment of calcineurin in CD11c-expressing cells (CD11ccrecnb1loxP) significantly increased susceptibility to systemic A. fumigatus infection and to intranasal infection in irradiated mice undergoing bone marrow transplant. Global expression profiling of bone marrow-derived DCs identified calcineurin-regulated processes in the immune response to infection, including expression of pentraxin-3, an important antifungal defense protein. These results suggest that calcineurin inhibition directly impairs important immunoprotective functions of myeloid cells, as shown by the higher susceptibility of CD11ccrecnbloxP mice in models of systemic and invasive pulmonary aspergillosis, including after allogeneic bone marrow transplantation. These findings are relevant to the clinical management of transplant patients with severe Aspergillus infections.
Asunto(s)
Aspergilosis/inmunología , Aspergillus fumigatus/inmunología , Trasplante de Médula Ósea , Proteína C-Reactiva/metabolismo , Calcineurina/metabolismo , Células Dendríticas/inmunología , Inmunosupresores/efectos adversos , Componente Amiloide P Sérico/metabolismo , Animales , Proteína C-Reactiva/genética , Antígeno CD11c/metabolismo , Calcineurina/genética , Inhibidores de la Calcineurina/efectos adversos , Inhibidores de la Calcineurina/uso terapéutico , Células Cultivadas , Susceptibilidad a Enfermedades , Regulación hacia Abajo , Rechazo de Injerto/prevención & control , Humanos , Inmunosupresores/uso terapéutico , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Componente Amiloide P Sérico/genética , Transducción de SeñalRESUMEN
Dendritic cells (DCs) play a critical role in orchestrating the innate and adaptive components of the immune system so that appropriate, coordinated responses are mounted against infectious agents. Tissue-resident DCs interact with microbes through germline-encoded pattern-recognition receptors (PRRs), which recognize molecular patterns expressed by various microorganisms. Antigens use PRR activation to instruct DCs for the appropriate priming of natural killer (NK) cells, followed by specific T-cell responses. Due to the central role of DCs in regulating the activation and progression of immune responses, minor imbalances in the feedback control of Toll-like receptor (TLR)-activated cells have been associated with autoimmunity in genetically prone individuals. We review here recent findings on the role of DCs in the priming of innate and adaptive immune responses and the possible involvement of DCs in inducing and maintaining autoimmune reactions.
Asunto(s)
Células Dendríticas/inmunología , Sistema Inmunológico/fisiología , Receptores de Reconocimiento de Patrones/inmunología , Antígenos/inmunología , Autoinmunidad/inmunología , Células Dendríticas/citología , Humanos , Inmunidad Innata/inmunología , Células Asesinas Naturales/inmunología , Activación de Linfocitos , Linfocitos T/inmunología , Receptores Toll-Like/inmunologíaRESUMEN
The dendritic cell lineage comprises cells at various stages of functional maturation that are able to induce and regulate the immune response against antigens and thus function as initiators of protective immunity. The signals that determine the given dendritic cell functions depend mostly on the local microenvironment and on the interaction between dendritic cells and microorganisms. These interactions are complex and very different from one pathogen to another; nevertheless, both shared and unique responses have been observed using global genomic analyses. In this review, we have focused on the study of host-pathogen interactions using a genome-wide transcriptional approach with a focus on cytokine family members.
Asunto(s)
Citocinas/inmunología , Células Dendríticas/inmunología , Sistema Inmunológico/fisiología , Animales , Linaje de la Célula , Quimiocinas/inmunología , Células Dendríticas/citología , Células Dendríticas/fisiología , Perfilación de la Expresión Génica , Humanos , Inmunidad Celular/fisiología , Inmunidad Innata/fisiología , Interleucina-2/inmunología , Células Asesinas Naturales/inmunología , Transcripción GenéticaRESUMEN
Immature dendritic cells (DCs) sample their environment for antigens and after stimulation present peptide associated with major histocompatibility complex class II (MHC II) to naive T cells. We have studied the intracellular trafficking of MHC II in cultured DCs. In immature cells, the majority of MHC II was stored intracellularly at the internal vesicles of multivesicular bodies (MVBs). In contrast, DM, an accessory molecule required for peptide loading, was located predominantly at the limiting membrane of MVBs. After stimulation, the internal vesicles carrying MHC II were transferred to the limiting membrane of the MVB, bringing MHC II and DM to the same membrane domain. Concomitantly, the MVBs transformed into long tubular organelles that extended into the periphery of the cells. Vesicles that were formed at the tips of these tubules nonselectively incorporated MHC II and DM and presumably mediated transport to the plasma membrane. We propose that in maturing DCs, the reorganization of MVBs is fundamental for the timing of MHC II antigen loading and transport to the plasma membrane.
Asunto(s)
Presentación de Antígeno , Células Dendríticas/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Vesículas Transportadoras/metabolismo , Animales , Células Cultivadas , Células Dendríticas/efectos de los fármacos , Células Dendríticas/metabolismo , Células Dendríticas/ultraestructura , Endocitosis/fisiología , Antígenos de Histocompatibilidad Clase II/metabolismo , Lipopolisacáridos/farmacología , Proteínas de la Membrana/metabolismo , Ratones , Ratones Endogámicos C57BL , Modelos Biológicos , Transporte de Proteínas , Regulación hacia ArribaRESUMEN
Cytomegalovirus (CMV), measles and HIV are the main human pathogens known to induce immunosuppression. Unlike measles and HIV, and despite the availability of a well studied animal model, little is known about the mechanisms that control CMV-induced immunosuppression. We hypothesized that dendritic cells (DCs), which are crucial in generating and maintaining immune responses, represent a target for CMV and that the transient, but profound, immunosuppression that accompanies CMV infection results from viral interference with DC functions. Here we show that DCs were permissive to murine CMV infection. In addition, DC infection prevented delivery of the signals required for T cell activation. Thus, CMV-mediated impairment of DC function may be crucial for virally induced immunosuppression and interleukin 2 is implicated as a key factor.
Asunto(s)
Infecciones por Citomegalovirus/inmunología , Citomegalovirus/patogenicidad , Células Dendríticas/virología , Tolerancia Inmunológica , Síndromes de Inmunodeficiencia/etiología , Animales , Citomegalovirus/fisiología , Infecciones por Citomegalovirus/complicaciones , Infecciones por Citomegalovirus/virología , Células Dendríticas/efectos de los fármacos , Células Dendríticas/inmunología , Endocitosis , Genes Reporteros , Huésped Inmunocomprometido , Síndromes de Inmunodeficiencia/inmunología , Operón Lac , Lipopolisacáridos/farmacología , Activación de Linfocitos , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Organismos Libres de Patógenos Específicos , Subgrupos de Linfocitos T/inmunología , Replicación Viral , beta-Galactosidasa/análisis , beta-Galactosidasa/biosíntesisRESUMEN
Immature and mature dendritic cells (DC) have been well characterized functionally and phenotypically. Microorganisms or bacterial products such as lipopolysaccharide (LPS) and inflammatory molecules, including tumor necrosis factor (TNF-alpha), are both believed to activate the DC maturation program which allows DC to initiate and amplify innate and adaptive immune responses. However, there is increasing evidence that the functional state of DC, induced by different stimuli, may be relevant for the immune response outcome. Thus, we compared the transcriptional program of mature, transitional and immature DC, after either LPS or TNF-alpha stimulation. GeneChip oligonucleotide microarrays, representing approximately 6,500 murine genes and ESTs, were used for this analysis. A very diverse modulation of gene expression was observed with the two stimuli. Only LPS-treated cells showed a pattern of expression of genes compatible with a definitive growth arrest and with a suitable activation and control of the immune response.
Asunto(s)
Células Dendríticas/inmunología , Animales , Presentación de Antígeno , Apoptosis , Ciclo Celular , Diferenciación Celular , Línea Celular , Citocinas/biosíntesis , Células Dendríticas/citología , Células Dendríticas/efectos de los fármacos , Perfilación de la Expresión Génica , Antígenos de Histocompatibilidad/inmunología , Inflamación/genética , Inflamación/inmunología , Lipopolisacáridos/farmacología , Ratones , Análisis de Secuencia por Matrices de Oligonucleótidos , Péptidos/inmunología , ARN Mensajero/biosíntesis , Activación Transcripcional , Factor de Necrosis Tumoral alfa/farmacologíaRESUMEN
Dendritic cells (DCs) are strong activators of primary T cell responses. Their priming ability is acquired upon encounter with maturation stimuli. To identify the genes that are differentially expressed upon maturation induced by exposure to Gram-negative bacteria, a kinetic study of DC gene expression was done with microarrays representing 11,000 genes and ESTs (expressed sequence tags). Approximately 3000 differentially expressed transcripts were identified. We found that functional interleukin 2 (IL-2) mRNA, which gave rise to IL-2 production, was transiently up-regulated at early time-points after bacterial encounter. In contrast, macrophages did not produce IL-2 upon bacterial stimulation. Thus, IL-2 is an additional key cytokine that confers unique T cell stimulatory capacity to DCs.
Asunto(s)
Células Dendríticas/inmunología , Interleucina-2/biosíntesis , Activación de Linfocitos , Animales , Médula Ósea/crecimiento & desarrollo , Células Cultivadas , Perfilación de la Expresión Génica , Bacterias Gramnegativas/inmunología , Interleucina-2/genética , Interleucina-2/fisiología , Cinética , Prueba de Cultivo Mixto de Linfocitos , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/biosíntesis , Linfocitos T/inmunologíaRESUMEN
Dendritic cells constitutively secrete a population of small (50-90 nm diameter) Ag-presenting vesicles called exosomes. When sensitized with tumor antigenic peptides, dendritic cells produce exosomes, which stimulate anti-tumor immune responses and the rejection of established tumors in mice. Using a systematic proteomic approach, we establish the first extensive protein map of a particular exosome population; 21 new exosomal proteins were thus identified. Most proteins present in exosomes are related to endocytic compartments. New exosomal residents include cytosolic proteins most likely involved in exosome biogenesis and function, mainly cytoskeleton-related (cofilin, profilin I, and elongation factor 1alpha) and intracellular membrane transport and signaling factors (such as several annexins, rab 7 and 11, rap1B, and syntenin). Importantly, we also identified a novel category of exosomal proteins related to apoptosis: thioredoxin peroxidase II, Alix, 14-3-3, and galectin-3. These findings led us to analyze possible structural relationships between exosomes and microvesicles released by apoptotic cells. We show that although they both represent secreted populations of membrane vesicles relevant to immune responses, exosomes and apoptotic vesicles are biochemically and morphologically distinct. Therefore, in addition to cytokines, dendritic cells produce a specific population of membrane vesicles, exosomes, with unique molecular composition and strong immunostimulating properties.
Asunto(s)
Apoptosis , Vesículas Citoplasmáticas/metabolismo , Células Dendríticas/metabolismo , Proteoma/metabolismo , Animales , Apoptosis/inmunología , Línea Celular , Membrana Celular/química , Membrana Celular/metabolismo , Membrana Celular/ultraestructura , Vesículas Citoplasmáticas/química , Vesículas Citoplasmáticas/ultraestructura , Citosol/química , Citosol/metabolismo , Citosol/ultraestructura , Células Dendríticas/química , Células Dendríticas/ultraestructura , Endocitosis/inmunología , Ratones , Mapeo Peptídico , Proteoma/análisis , Proteoma/ultraestructura , Fracciones Subcelulares/química , Fracciones Subcelulares/metabolismo , Fracciones Subcelulares/ultraestructura , Células Tumorales CultivadasRESUMEN
Dendritic cell (DC) maturation is essential for the initiation of T-dependent immune responses. Nuclear factor kappa B/Rel (NF kappa B/Rel) transcription factors are ubiquitously expressed signalling molecules, known to regulate the transcription of a large number of genes involved in immune responses, including cytokines such as IL-1, IL-6, TNF-alpha and cell surface molecules (MHC class I and II, B7.2). In this study, we have compared the activation of five members of the NF-kappa B family, p65, c-Rel, p50, RelB and p52, during DC maturation in response to lipopolysaccharide (LPS) and to Salmonella typhimurium. We have shown that although the translocation of NF-kappa B occurred very early, 30 min after treatment with both S. typhimurium and LPS, bacteria-induced NF-kappa B activation was more pronounced. Four out of five members, i.e. p65, c-Rel, p50 and RelB, were similarly activated upon the two stimuli but with different kinetics. Indeed, we have observed that p65, c-Rel and p50 were translocated early, whereas RelB was translocated later in DC activation. This differential regulation suggests that the various members of NF-kappa B family can mediate distinct functions of DC physiology.
Asunto(s)
Células Dendríticas/inmunología , Lipopolisacáridos/inmunología , FN-kappa B/metabolismo , Salmonella typhimurium/inmunología , Transducción de Señal , Animales , Diferenciación Celular , Núcleo Celular/metabolismo , Medios de Cultivo , Células Dendríticas/citología , Células Dendríticas/metabolismo , Regulación de la Expresión Génica , Ratones , Subunidad p50 de NF-kappa B , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Proto-Oncogénicas c-rel/metabolismo , Factor de Transcripción ReIA , Factor de Transcripción ReIB , Factores de Transcripción/metabolismo , Transcripción GenéticaRESUMEN
The adenylate cyclase toxin (CyaA) of Bordetella pertussis is a major virulence factor required for the early phases of lung colonization. It can invade eukaryotic cells where, upon activation by endogenous calmodulin, it catalyzes the formation of unregulated cAMP levels. CyaA intoxication leads to evident toxic effects on macrophages and neutrophils. Here, we demonstrate that CyaA uses the alpha(M)beta(2) integrin (CD11b/CD18) as a cell receptor. Indeed, the saturable binding of CyaA to the surface of various hematopoietic cell lines correlated with the presence of the alpha(M)beta(2) integrin on these cells. Moreover, binding of CyaA to various murine cell lines and human neutrophils was specifically blocked by anti-CD11b monoclonal antibodies. The increase of intracellular cAMP level and cell death triggered by CyaA intoxication was also specifically blocked by anti-CD11b monoclonal antibodies. In addition, CyaA bound efficiently and triggered intracellular cAMP increase and cell death in Chinese hamster ovary cells transfected with alpha(M)beta(2) (CD11b/CD18) but not in cells transfected with the vector alone or with the alpha(X)beta(2) (CD11c/CD18) integrin. Thus, the cellular distribution of CD11b, mostly on neutrophils, macrophages, and dendritic and natural killer cells, supports a role for CyaA in disrupting the early, innate antibacterial immune response.
Asunto(s)
Adenilil Ciclasas/metabolismo , Proteínas Bacterianas/metabolismo , Bordetella pertussis/metabolismo , Antígenos CD18/metabolismo , Antígeno de Macrófago-1/metabolismo , Precursores de Proteínas/metabolismo , Toxina de Adenilato Ciclasa , Animales , Anticuerpos Monoclonales/metabolismo , Antígenos CD18/genética , Células CHO , Calcio , Cationes Bivalentes , Línea Celular , Cricetinae , AMP Cíclico/metabolismo , Humanos , Antígeno de Macrófago-1/genética , Magnesio , Ratones , RatasRESUMEN
Microglia arise from CD45(+) bone marrow precursors that colonize the fetal brain and play a key role in central nervous system inflammatory conditions. We report that parenchymal microglia are uncommitted myeloid progenitors of immature dendritic cells and macrophages by several criteria, including surface expression of "empty" class II MHC protein and their cysteine protease (cathepsin) profile. Microglia express receptors for stem cell factor and can be skewed toward more dendritic cell or macrophage-like profiles in response to the lineage growth factors granulocyte/macrophage colony-stimulating factor or macrophage colony-stimulating factor. Thus, in contrast to other organs, where terminally differentiated populations of resident dendritic cells and/or macrophages outnumber colonizing precursors, the majority of microglia within the brain remain in an undifferentiated state.
Asunto(s)
Microglía/inmunología , Plasticidad Neuronal/inmunología , Animales , Catepsinas/genética , Catepsinas/inmunología , Diferenciación Celular , Células Cultivadas , Sistema Nervioso Central/citología , Sistema Nervioso Central/inmunología , Células Dendríticas/inmunología , Factor Estimulante de Colonias de Granulocitos y Macrófagos/farmacología , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Interferón gamma/inmunología , Interferón gamma/farmacología , Macrófagos/inmunología , Proteínas de la Membrana/biosíntesis , Ratones , Microglía/citología , Microglía/efectos de los fármacos , Factor de Células Madre/biosíntesisRESUMEN
Dendritic cells (DCs) are considered the most potent antigen-presenting cells and probably the only ones able to prime naive T cells. Indeed, DCs are distributed in tissues that interface the external environment, where they act as sentinels for incoming bacteria, viruses, and fungi. We have previously analyzed the capacity of DCs to interact with bacteria, and we have shown that bacteria can act as "Trojan horses," delivering heterologous proteins to DCs in a processed form that allows extremely efficient loading of both MHC class I and class II molecules. In this study, we have optimized the usage of recombinant bacteria as an antigen delivery system for DCs, with the aim to develop a new DC vaccination strategy in antitumor immunity. We have focused on a low immunogenic antigen, the tyrosinase-related protein-2 (Trp-2), a self-antigen expressed in mouse and human melanoma for which induction of antitumor immunity has proven to be very ineffective. We have given mice injections of either Trp-2/recombinant bacteria-loaded DCs or with bacteria alone engineered to express the Trp-2 melanoma antigen. We have shown that only DCs loaded with recombinant bacteria, but not with wild-type bacteria, were able to induce Trp-2-specific CTLs and immunity against the B16 tumor. Immunity was obtained in experiments of tumor vaccination as well as in experiments of tumor therapy. When therapy with bacteria-loaded DCs was performed in B16 tumor-bearing mice, 60% of the treated mice were tumor free 2 months after the initial tumor growth.
Asunto(s)
Antígenos de Neoplasias/metabolismo , Células Dendríticas/metabolismo , Oxidorreductasas Intramoleculares/metabolismo , Animales , Humanos , Melanoma Experimental/metabolismo , Melanoma Experimental/prevención & control , Ratones , Ratones Endogámicos C57BL , Trasplante de Neoplasias , Fenotipo , Salmonella typhimurium/metabolismo , Bazo/citología , Bazo/metabolismo , Linfocitos T Citotóxicos/metabolismo , Factores de TiempoRESUMEN
Penetration of the gut mucosa by pathogens expressing invasion genes is believed to occur mainly through specialized epithelial cells, called M cells, that are located in Peyer's patches. However, Salmonella typhimurium that are deficient in invasion genes encoded by Salmonella pathogenicity island 1 (SPI1) are still able to reach the spleen after oral administration. This suggests the existence of an alternative route for bacterial invasion, one that is independent of M cells. We report here a new mechanism for bacterial uptake in the mucosa tissues that is mediated by dendritic cells (DCs). DCs open the tight junctions between epithelial cells, send dendrites outside the epithelium and directly sample bacteria. In addition, because DCs express tight-junction proteins such as occludin, claudin 1 and zonula occludens 1, the integrity of the epithelial barrier is preserved.
Asunto(s)
Células Dendríticas/inmunología , Células Dendríticas/ultraestructura , Sistema Digestivo/inmunología , Sistema Digestivo/microbiología , Uniones Estrechas/inmunología , Animales , Células CACO-2 , Línea Celular , Técnicas de Cocultivo , Células Dendríticas/metabolismo , Células Epiteliales/inmunología , Células Epiteliales/microbiología , Células Epiteliales/ultraestructura , Humanos , Mucosa Intestinal/inmunología , Mucosa Intestinal/microbiología , Proteínas de la Membrana/metabolismo , Ratones , Microscopía Electrónica , Modelos Biológicos , Salmonella typhimurium/inmunología , Salmonella typhimurium/patogenicidad , Uniones Estrechas/metabolismo , Uniones Estrechas/ultraestructuraRESUMEN
Suppressive activities involving T-B and T-T cell interactions are important to maintain immune system homeostasis. Negative control of IgG2ab+ B cells by anti-IgG2ab T cells derived from Igha mice has been well documented. Nevertheless the real contribution of anti-IgG2ab T cells, endogenously matured in Ighb mice, in controlling IgG2ab+ B cell function has never been investigated. We previously generated anti-IgG2ab TCR-transgenic mice and showed that transgenic T cells were not deleted in the thymus and that they were responsible for a complete and chronic IgG2ab suppression. Here we show that T cells expressing high density of anti-IgG2ab TCR were positively selected in the thymus with a higher efficiency in animals expressing IgG2ab, reached peripheral lymphoid organs and negatively controlled IgG2ab serum levels. Moreover, anti-IgG2ab T cells transgenic for the single TCR chain, thus undergoing normal rearrangements and normal processes of selection, also reached the periphery and suppressed IgG2ab. Interestingly, concentration of IgG2ab in serum inversely correlated with the peripheral frequency of Ig-specific T cells. Finally, T cells able to suppress IgG2ab were obtained from Ighb non-transgenic mice, indicating that anti-2ab T cells are naturally present in the periphery of Ighb animals. We propose that IgG2ab-specific T cells contribute to determine IgG2ab serum levels in Ighb mice.
Asunto(s)
Linfocitos B/fisiología , Comunicación Celular , Inmunoglobulina G/sangre , Isotipos de Inmunoglobulinas/inmunología , Linfocitos T/fisiología , Animales , Inmunoglobulina G/clasificación , Inmunoglobulina G/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Receptores de Antígenos de Linfocitos T/fisiologíaRESUMEN
Dendritic cells (DC) are now recognized as major players in the control of immune responses (1), since they direct both the quality and the extent of the adaptative response. Thus, DC represent a very appropriate means for the manipulation of harmful or protective immunity (2-4).
RESUMEN
Understanding the mechanisms governing the type of induced immune response after microbial invasion, could be of crucial importance for the rational design of a bacteria-based vaccine. Targeting a vaccine directly to dendritic cells (DCs), which are considered the most powerful antigen presenting cells, could be extremely effective. Here we describe that CD11b+CD8alpha- dendritic cells are involved in the direct bacterial uptake across mucosal surfaces. DCs are widely spread in the lamina propria of the gut and are recruited at the site of infection. DCs open the tight junctions between epithelial cells, send dendrites outside of the epithelium and sample bacteria. Moreover, the integrity of the epithelial barrier is preserved because DCs express tight junction proteins, such as occludin, claudin 1 and Junctional Adhesion Molecule (JAM) and can establish tight junctions-like structures with neighbouring epithelial cells.
Asunto(s)
Células Dendríticas/microbiología , Salmonella typhimurium/inmunología , Animales , Células CACO-2 , Moléculas de Adhesión Celular/genética , Línea Celular , Claudina-1 , Células Dendríticas/inmunología , Células Epiteliales/inmunología , Células Epiteliales/microbiología , Humanos , Mucosa Intestinal/inmunología , Mucosa Intestinal/microbiología , Moléculas de Adhesión de Unión , Proteínas de la Membrana/genética , Ratones , OcludinaRESUMEN
Ligation of the Fas (CD95) receptor leads to an apoptotic death signal in T cells, B cells, and macrophages. However, human CD34(+)-derived dendritic cells (DCs) and mouse DCs, regardless of their maturation state, are not susceptible to Fas-induced cell death. This resistance correlates with the constitutive expression of the Fas-associated death domain-like IL-1beta-converting enzyme (FLICE)-inhibitory protein (FLIP) ligand. We demonstrate a new role of Fas in DC physiology. Engagement of Fas on immature DCs by Fas ligand (FasL) or by anti-Fas antibodies induces the phenotypical and functional maturation of primary DCs. Fas-activated DCs upregulate the expression of the major histocompatibility complex class II, B7, and DC-lysosome-associated membrane protein (DC-LAMP) molecules and secrete proinflammatory cytokines, in particular interleukin (IL)-1beta and tumor necrosis factor alpha. Mature DCs, if exposed to FasL, produce even higher amounts of IL-1beta. Importantly, it is possible to reduce the production of IL-1beta and interferon (IFN)-gamma during DC-T cell interaction by blocking the coupling of Fas-FasL with a Fas competitor. Finally, during cognate DC-T cell recognition, IL-12 (p70) could not be detected at early or late time points, indicating that Fas-induced, IFN-gamma secretion is independent of IL-12.
Asunto(s)
Células Dendríticas/inmunología , Inflamación/inmunología , Interferón gamma/biosíntesis , Interleucina-12/inmunología , Interleucina-1/metabolismo , Péptidos y Proteínas de Señalización Intracelular , Glicoproteínas de Membrana/inmunología , Linfocitos T/inmunología , Receptor fas/inmunología , Apoptosis/efectos de los fármacos , Proteína Reguladora de Apoptosis Similar a CASP8 y FADD , Proteínas Portadoras/biosíntesis , Diferenciación Celular , Células Cultivadas , Células Dendríticas/citología , Células Dendríticas/efectos de los fármacos , Proteína Ligando Fas , Humanos , Lipopolisacáridos/farmacología , Mitógenos/farmacología , Fenotipo , Factor de Necrosis Tumoral alfa/farmacología , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Immunization with peptide or recombinant proteins generally fails to elicit CTL, which are thought to play a key role in the control of virus-infected cells and tumor growth. In this study we show that the nontoxic B subunit of Shiga toxin fused to a tumor peptide derived from the mouse mastocytoma P815 can induce specific CTL in mice without the use of adjuvant. The Shiga B subunit acts as a vector rather than as an adjuvant, because coinjection of the tumor peptide and the B subunit as separate entities does not lead to CTL induction. We also demonstrated that in vitro the B subunit mediates the delivery of various exogenous CD8 T cell epitopes into the conventional MHC class I-restricted pathway, as this process is inhibited by brefeldin A and lactacystin and requires a functional TAP system. In contrast to other nonviral methods for transport of exogenous Ags into the endogenous MHC class I pathway that involve macropinocytosis or phagocytosis, the Shiga B subunit targets this pathway in a receptor-dependent manner, namely via binding to the glycolipid Gb3. Because this receptor is highly expressed on various dendritic cells, it should allow preferential targeting of the Shiga B subunit to these professional APCs. Therefore, the Shiga B subunit appears to represent an attractive vector for vaccine development due to its ability to target dendritic cells and to induce specific CTL without the need for adjuvant.
Asunto(s)
Acetilcisteína/análogos & derivados , Presentación de Antígeno/genética , Antígenos de Neoplasias/genética , Toxinas Bacterianas/inmunología , Células Dendríticas/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , Péptidos/inmunología , Proteínas Recombinantes de Fusión/inmunología , Linfocitos T Citotóxicos/inmunología , Transportador de Casetes de Unión a ATP, Subfamilia B, Miembro 2 , Transportadoras de Casetes de Unión a ATP/genética , Transportadoras de Casetes de Unión a ATP/fisiología , Acetilcisteína/farmacología , Animales , Presentación de Antígeno/efectos de los fármacos , Antígenos de Neoplasias/administración & dosificación , Antígenos de Neoplasias/inmunología , Toxinas Bacterianas/administración & dosificación , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Brefeldino A/farmacología , Citotoxicidad Inmunológica/genética , Células Dendríticas/metabolismo , Femenino , Inyecciones Intraperitoneales , Líquido Intracelular/inmunología , Líquido Intracelular/metabolismo , Leucemia L1210 , Activación de Linfocitos/genética , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Ratones Noqueados , Ovalbúmina/administración & dosificación , Ovalbúmina/inmunología , Ovalbúmina/metabolismo , Péptidos/metabolismo , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Procesamiento Proteico-Postraduccional/inmunología , Proteínas Recombinantes de Fusión/administración & dosificación , Proteínas Recombinantes de Fusión/genética , Sarcoma Experimental/genética , Sarcoma Experimental/inmunología , Toxinas Shiga , Transducción de Señal/genética , Transducción de Señal/inmunología , Linfocitos T Citotóxicos/metabolismo , Células Tumorales CultivadasRESUMEN
In order to protect the body from infectious microorganisms, mammals have developed powerful lines of defense, consisting in innate and adaptive immune responses. The innate response is phylogenetically more ancient and, for a long time, it has been considered to be broadly directed to microorganisms. However, the discovery of a new class of receptors, involved in recognition of patterns characteristic of groups of microorganisms (the toll-like receptor family) has re-evaluated the role of the innate immune system as a discriminating system. Indeed, there is increasing evidence that the induction of different types of effector adaptive responses are directed by the innate immune system after recognition of particular groups of pathogens. The central role of Dendritic cells (DC) in the induction of adaptive immune responses towards infectious agents has been extensively described, but, recently, a new role of DC as a link between the non-antigen- and the antigen-specific responses has been proposed. DC have, indeed, the capacity to recruit and activate cells of the innate immune system upon inflammation. Thus. understanding the interaction of bacteria with DC, and the early molecular events resulting from this interaction may shed some light on the mechanisms of initiation of the immune response to infectious agents and on aspects of invasiveness, pathogenicity, and the persistence of certain bacteria.
Asunto(s)
Bacterias/inmunología , Bacterias/patogenicidad , Células Dendríticas/citología , Células Dendríticas/inmunología , Animales , Presentación de Antígeno , Antígenos Bacterianos , Proteínas Bacterianas/inmunología , Diferenciación Celular , Quimiocinas/inmunología , Humanos , Lipopolisacáridos/inmunología , Receptores de Superficie Celular/inmunología , Receptores de Quimiocina/metabolismoRESUMEN
The well defined, immature murine dendritic cell (DC) line D1 was used to study the role of DC maturation in CTL induction in vitro and in vivo. Maturation of D1 cells, characterized by markedly increased expression of MHC and costimulatory molecules, was induced by incubation with lipopolysaccharide, agonistic CD40 antibody, or specific CD4(+) T helper (Th) cells. Activated, but not immature, D1 cells efficiently primed alloreactive T cell responses in vitro. Similarly, priming of CTL immunity in vivo in CD4-depleted mice was only observed if these mice were immunized with activated D1 cells. This study provides formal evidence that activation of DCs, induced by Th-independent as well as Th-dependent stimuli, is essential for efficient induction of CTL responses.