RESUMEN
It is known that conventional antigen presentation involves phagocytosis of antigens followed by its internalization in endocytic compartments and presentation of epitopes through MHC class II molecules for CD4 T cells. However, since 1976 a cross-presentation pathway has been studied, in which CD8 T cells are activated via MHC class I with antigens acquired through phagocytosis or endocytosis by dendritic cells (DCs). Among some important molecules involved in the cross-presentation, the C-type lectin receptor of the Dectin-1 cluster (CLECs), particularly the CLEC9A receptor, not only is expressed in dendritic cells but also presents a pivotal role in this context. In special, CLEC12A has been highlighted as a malaria pigment hemozoin (HZ) receptor. During Plasmodium infection, hemozoin crystals defend the parasite against heme toxicity within erythrocytes, as well as the released native HZ elicits pro-inflammatory responses and can induce cross-presentation. Particularly, this crystal can be synthesized from hematin anhydride and mimics the native form, and the gaps generated between the nanocrystal domains during its synthesis allow for substance coupling followed by its coating. Therefore, this study aimed to assess whether synthetic hemozoin (sHz) or hematin anhydride could be a nanocarrier and promote cross-presentation in dendritic cells. Firstly, it was verified that sHz can carry coated and coupled antigens, the compounds can associate to LAMP1-positive vesicles and decrease overall intracellular pH, which can potentially enhance the cross-presentation of ovalbumin and Leishmania infantum antigens. Thus, this study adds important data in the molecular intricacies of antigen presentation by showing not only the sHz immunomodulatory properties but also its potential applications as an antigen carrier.
Asunto(s)
Presentación de Antígeno , Reactividad Cruzada , Células Dendríticas , Hemoproteínas , Hemoproteínas/inmunología , Reactividad Cruzada/inmunología , Animales , Células Dendríticas/inmunología , Ratones , Nanopartículas/química , Humanos , Malaria/inmunología , Lectinas Tipo C/metabolismo , Lectinas Tipo C/inmunología , Ovalbúmina/inmunologíaRESUMEN
Dendritic cells (DCs) have a specialized endomembrane system capable of presenting exogenous antigens in the context of MHC class I (MHC-I) molecules. This process, named cross-presentation, is crucial to activate CD8+ T lymphocytes and initiate cytotoxic immune responses. In this report, we present an Agent-Based Model in combination with Ordinary Differential Equations with enough complexity to reproduce cross-presentation. The model embraces the secretory and endocytic pathways, in connection with the plasma membrane, the endoplasmic reticulum, and the cytosol. Key molecules required for cross-presentation were included as cargoes. In the simulations, the kinetics of MHC-I uptake and recycling, and cross-presentation accurately reproduced experimental values. The model proved to be a suitable tool to elaborate hypotheses and design experiments. In particular, the model predictions and the experimental results obtained indicate that the rate-limiting step in cross-presentation of soluble ovalbumin is MHC-I loading after proteasomal processing of the antigenic protein.
Asunto(s)
Presentación de Antígeno , Reactividad Cruzada , Cinética , Ovalbúmina , Linfocitos T CD8-positivosRESUMEN
During cross-presentation, exogenous antigens (i.e. intracellular pathogens or tumor cells) are internalized and processed within the endocytic system and also by the proteasome in the cytosol. Then, antigenic peptides are associated with Major Histocompatibility Complex (MHC) class I molecules and these complexes transit to the plasma membrane in order to trigger cytotoxic immune responses through the activation of CD8+ T lymphocytes. Dendritic cells (DCs) are particularly adapted to achieve efficient antigen cross-presentation and their endocytic network displays important roles during this process, including a sophisticated MHC-I transport dependent on recycling compartments. In this study, we show that C. trachomatis, an obligate intracellular pathogen that exhibits multiple strategies to evade the immune system, is able to induce productive infections in the murine DC line JAWS-II. Our results show that when C. trachomatis infects these cells, the bacteria-containing vacuole strongly recruits host cell recycling vesicles, but no other endosomal compartments. Furthermore, we found that chlamydial infection causes significant alterations of MHC-I trafficking in JAWS-II DCs: reduced levels of MHC-I expression at the cell surface, disruption of the perinuclear MHC-I intracellular pool, and impairment of MHC-I endocytic recycling to the plasma membrane. We observed that all these modifications lead to a hampered cross-presentation ability of soluble and particulate antigens by JAWS-II DCs and primary bone marrow-derived DCs. In summary, our findings provide substantial evidence that C. trachomatis hijacks the DC endocytic recycling system, causing detrimental changes on MHC-I intracellular transport, which are relevant for competent antigen cross-presentation.
Asunto(s)
Presentación de Antígeno/inmunología , Chlamydia trachomatis/inmunología , Reactividad Cruzada/inmunología , Células Dendríticas/inmunología , Células Dendríticas/microbiología , Antígenos de Histocompatibilidad Clase I/inmunología , Animales , Células de la Médula Ósea/inmunología , Línea Celular , Chlamydia trachomatis/patogenicidad , Endocitosis , Ratones , Ratones Endogámicos C57BL , Transporte de ProteínasRESUMEN
Tissue-resident memory CD8+ T (Trm) cells mediate potent local innate and adaptive immune responses and play a central role against solid tumors. However, whether Trm cells cross-talk with dendritic cells (DCs) to support anti-tumor immunity remains unclear. Here we show that antigen-specific activation of skin Trm cells leads to maturation and migration to draining lymph nodes of cross-presenting dermal DCs. Tumor rejection mediated by Trm cells triggers the spread of cytotoxic CD8+ T cell responses against tumor-derived neo- and self-antigens via dermal DCs. These responses suppress the growth of intradermal tumors and disseminated melanoma lacking the Trm cell-targeted epitope. Moreover, analysis of RNA sequencing data from human melanoma tumors reveals that enrichment of a Trm cell gene signature associates with DC activation and improved survival. This work unveils the ability of Trm cells to amplify the breath of cytotoxic CD8+ T cell responses through DCs, thereby strengthening anti-tumor immunity.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Células Dendríticas/inmunología , Memoria Inmunológica/inmunología , Melanoma/inmunología , Piel/inmunología , Animales , Antígenos/inmunología , Movimiento Celular/inmunología , Reactividad Cruzada/inmunología , Humanos , Ganglios Linfáticos/inmunología , Melanoma/patología , Ratones Endogámicos C57BL , Ratones Transgénicos , Piel/citología , Linfocitos T Citotóxicos/inmunologíaRESUMEN
Cross-presentation is an important mechanism for the differentiation of effector cytotoxic T lymphocytes (CTL) from naïve CD8+ T-cells, a key response for the clearance of intracellular pathogens and tumors. The liposomal co-encapsulation of the pore-forming protein sticholysin II (StII) with ovalbumin (OVA) (Lp/OVA/StII) induces a powerful OVA-specific CTL activation and an anti-tumor response in vivo. However, the pathway through which the StII contained in this preparation is able to induce antigen cross-presentation and the type of professional antigen presenting cells (APCs) involved have not been elucidated. Here, the ability of mouse bone marrow-derived dendritic cells (BM-DCs) and macrophages (BM-MΦs) stimulated with Lp/OVA/StII to activate SIINFEKL-specific B3Z CD8+ T cells was evaluated in the presence of selected inhibitors. BM-MΦs, but not BM-DCs were able to induce SIINFEKL-specific B3Z CD8+ T cell activation upon stimulation with Lp/OVA/StII. The cross-presentation of OVA was markedly decreased by the lysosome protease inhibitors, leupeptin and cathepsin general inhibitor, while it was unaffected by the proteasome inhibitor epoxomicin. This process was also significantly reduced by phagocytosis and Golgi apparatus function inhibitors, cytochalasin D and brefeldin A, respectively. These results are consistent with the concept that BM-MΦs internalize these liposomes through a phagocytic mechanism resulting in the cross-presentation of the encapsulated OVA by the vacuolar pathway. The contribution of macrophages to the CTL response induced by Lp/OVA/StII in vivo was determined by depleting macrophages with clodronate-containing liposomes. CTL induction was almost completely abrogated in mice depleted of macrophages, demonstrating the relevance of these APCs in the antigen cross-presentation induced by this formulation.
Asunto(s)
Venenos de Cnidarios/metabolismo , Células Dendríticas/fisiología , Macrófagos/fisiología , Linfocitos T Citotóxicos/inmunología , Vacuolas/metabolismo , Animales , Antígenos/inmunología , Antígenos CD8/metabolismo , Células Cultivadas , Venenos de Cnidarios/química , Reactividad Cruzada , Femenino , Leupeptinas/farmacología , Liposomas/química , Activación de Linfocitos , Ratones , Ratones Endogámicos C57BL , Ovalbúmina/inmunologíaRESUMEN
The IRE1α/XBP1s signaling pathway is an arm of the unfolded protein response (UPR) that safeguards the fidelity of the cellular proteome during endoplasmic reticulum (ER) stress, and that has also emerged as a key regulator of dendritic cell (DC) homeostasis. However, in the context of DC activation, the regulation of the IRE1α/XBP1s axis is not fully understood. In this work, we report that cell lysates generated from melanoma cell lines markedly induce XBP1s and certain members of the UPR such as the chaperone BiP in bone marrow derived DCs (BMDCs). Activation of IRE1α endonuclease upon innate recognition of melanoma cell lysates was required for amplification of proinflammatory cytokine production and was necessary for efficient cross-presentation of melanoma-associated antigens without modulating the MHC-II antigen presentation machinery. Altogether, this work provides evidence indicating that ex-vivo activation of the IRE1α/XBP1 pathway in BMDCs enhances CD8+ T cell specific responses against tumor antigens.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Endorribonucleasas/metabolismo , Melanoma/inmunología , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de Señal/inmunología , Animales , Linfocitos T CD8-positivos/metabolismo , Línea Celular Tumoral , Reactividad Cruzada/efectos de los fármacos , Citocinas/inmunología , Citocinas/metabolismo , Células Dendríticas/efectos de los fármacos , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Estrés del Retículo Endoplásmico/inmunología , Endorribonucleasas/antagonistas & inhibidores , Endorribonucleasas/genética , Endorribonucleasas/inmunología , Humanos , Himecromona/análogos & derivados , Himecromona/farmacología , Activación de Linfocitos/efectos de los fármacos , Melanoma/patología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Cultivo Primario de Células , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/inmunología , Transducción de Señal/efectos de los fármacos , Respuesta de Proteína Desplegada/inmunología , Proteína 1 de Unión a la X-Box/inmunología , Proteína 1 de Unión a la X-Box/metabolismoRESUMEN
Despite eliciting a potent CD8+ T cell response, Brucella abortus is able to persist and establish a chronic infection inside its host. We have previously reported that the infection of human monocytes/macrophages with B. abortus inhibits the IFN-γ-induced MHC-I cell surface expression down-modulating cytotoxic CD8+ T cell responses. MHC-I down-modulation depends on bacterial viability and results from the capacity of B. abortus to retain the MHC-I molecules within the Golgi apparatus. Furthermore, we recently demonstrated that epidermal growth factor receptor (EGFR) pathway is involved in this phenomenon and that this is an early event during infection. However, the components and mechanisms whereby B. abortus is able to down-modulate MHC-I remained to be elucidated. In this study we demonstrated that the down-modulation of MHC-I expression is not mediated by well-known Brucella virulence factors but instead by B. abortus RNA, a PAMP associated to viability (vita-PAMP). Surprisingly, completely degraded RNA was also able to inhibit MHC-I expression to the same extent as intact RNA. Accordingly, B. abortus RNA and its degradation products were able to mimic the MHC-I intracellular retention within the Golgi apparatus observed upon infection. We further demonstrated that TLR8, a single-stranded RNA and RNA degradation products sensor, was involved in MHC-I inhibition. On the other hand, neutralization of the EGFR reversed the MHC-I inhibition, suggesting a connection between the TLR8 and EGFR pathways. Finally, B. abortus RNA-treated macrophages display diminished capacity of antigen presentation to CD8+ T cells. Overall, our results indicate that the vita-PAMP RNA as well as its degradation products constitute novel virulence factors whereby B. abortus, by a TLR8-dependent mechanism and through the EGFR pathway, inhibits the IFN-γ-induced MHC-I surface expression on human monocytes/macrophages. Thus, bacteria can hide within infected cells and avoid the immunological surveillance of cytotoxic CD8+ T cells.
Asunto(s)
Brucelosis/inmunología , Receptores ErbB/inmunología , Evasión Inmune/inmunología , Monocitos/inmunología , ARN Bacteriano/inmunología , Receptor Toll-Like 8/inmunología , Animales , Brucella abortus/inmunología , Reactividad Cruzada/inmunología , Regulación hacia Abajo , Ensayo de Inmunoadsorción Enzimática , Citometría de Flujo , Antígenos de Histocompatibilidad Clase I/biosíntesis , Humanos , Ratones , Ratones Endogámicos C57BL , Microscopía Confocal , Monocitos/microbiología , Transducción de Señal/inmunologíaRESUMEN
Cervical cancer is a major public health problem and one of the leading causes of cancer deaths in women. Virtually all cases of cervical cancer, as well as a growing share of anal and head/neck tumors, are associated with human papillomavirus (HPV) infection. Despite the effectiveness, the available prophylactic vaccines do not benefit women with cervical lesions or cancer. Therefore, the search of new immunotherapeutic approaches to treat HPV-induced tumors is still a priority. The present study characterizes a therapeutic antitumor vaccine based on the genetic fusion of the Herpes simplex virus-1 (HSV-1) glycoprotein D (gD) with the E7 oncoprotein from HPV-16 (gDE7). Two subcutaneous doses of gDE7, admixed with poly (I:C), conferred complete and long-lasting therapeutic antitumor protection on mice previously challenged with tumor cells expressing the HPV-16 oncoproteins. The vaccine induced multifunctional E7-specific CD8+ T cells with cytotoxic activity and effector memory phenotype (CD44+ CD62Llow). In addition, gDE7 admixed with poly (I:C) vaccination controlled the expansion of tumor-induced regulatory T cells and myeloid-derived suppressor cells. More importantly, gDE7 activated mouse CD11c+ CD8α+ and human BDCA3+ dendritic cells (DC), specialized in antigen cross-presentation to CD8+ T cells, under in vitro conditions. These results indicated that the activation of a specific DC population, mediated by gD, improved the antigen-specific immune responses and the therapeutic performance induced by antitumor vaccines. These results open perspectives for the clinical testing of gDE7-based vaccines under the concept of active immunization as a tool for the therapeutic control of cancer. Mol Cancer Ther; 16(9); 1922-33. ©2017 AACR.
Asunto(s)
Vacunas contra el Cáncer/inmunología , Células Dendríticas/inmunología , Neoplasias/etiología , Neoplasias/patología , Papillomaviridae/inmunología , Infecciones por Papillomavirus/complicaciones , Infecciones por Papillomavirus/inmunología , Proteínas del Envoltorio Viral/inmunología , Animales , Presentación de Antígeno/inmunología , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Línea Celular Tumoral , Reactividad Cruzada/inmunología , Células Dendríticas/metabolismo , Femenino , Humanos , Inmunización , Memoria Inmunológica , Ratones , Ratones Noqueados , Neoplasias/terapia , Proteínas E7 de Papillomavirus/inmunología , Poli I-C , Especificidad del Receptor de Antígeno de Linfocitos T , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismoRESUMEN
The mechanisms underlying host HIV control hold much promise in the search for a functional HIV cure. We investigated the host genomic signatures in elite controllers or rapid progressors following recent infection and the correlates of immune reconstitution during combination antiretroviral therapy. We characterized the HIV-specific longitudinal host transcriptional response of peripheral blood mononuclear cells from elite controllers, rapid progressors, immune responders and non-responders using a RT-qPCR array in a cohort of recently HIV-infected Brazilian individuals. The elite controllers expressed unique transcripts early in infection that were closely associated with specialized cross-presentation between XCR1+ DCs and antigen-specific CD8+ T cells (XCL1). The natural suppression of HIV was also associated with the highly functional co-expression of cytokines and chemokines (CCL2, TNF and IL-10) concomitant with the maintenance of important anti-inflammatory and anticoagulant properties (Antithrombin III). Immune responders exhibited exclusively upregulated mRNAs possibly related to stem cell mobilization before combination antiretroviral therapy (neutrophil elastase). Our longitudinal approach to gene expression permitted us to discover previously unrecognized determinants that contribute to natural or antiretroviral-mediated HIV-1 immune control.
Asunto(s)
Infecciones por VIH/inmunología , VIH-1/inmunología , Leucocitos Mononucleares/inmunología , Transcriptoma/inmunología , Terapia Antirretroviral Altamente Activa , Antitrombina III/genética , Antitrombina III/inmunología , Antivirales/uso terapéutico , Brasil , Recuento de Linfocito CD4 , Quimiocinas/genética , Quimiocinas/inmunología , Estudios de Cohortes , Reactividad Cruzada/inmunología , Citocinas/genética , Citocinas/inmunología , Perfilación de la Expresión Génica/métodos , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/genética , Sobrevivientes de VIH a Largo Plazo , VIH-1/efectos de los fármacos , Antígenos HLA-B/inmunología , Interacciones Huésped-Patógeno/efectos de los fármacos , Interacciones Huésped-Patógeno/inmunología , Humanos , Leucocitos Mononucleares/efectos de los fármacos , Leucocitos Mononucleares/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transcriptoma/efectos de los fármacosRESUMEN
El objetivo del presente trabajo fue estudiar la presencia de reactividad cruzada de la prueba de tamizaje htTG/DGP para enfermedad celíaca (EC) con otros autoanticuerpos presentes en altos títulos en diferentes enfermedades autoinmunes (EA). Se realizó un estudio de corte transversal donde se seleccionaron 100 pacientes no celíacos, de ambos sexos (15 hombres, 85 mujeres) con edades entre 4 y 86 años que presentaban diversas EA. Para estudiar presencia de EC se realizaron por ELISA los ensayos QUANTALite® (INOVA Diagnostics, EE.UU.): htTG/DGPScreen, htTG IgA e IgG, Gliadina IgAII e IgGII. Los autoanticuerpos de otras EA se determinaron por inmunofluorescencia indirecta y por electroquimioluminiscencia. La reactividad cruzada encontrada con autoanticuerpos no específicos de EC fue de 2,0%. Las dos muestras positivas con la prueba de tamizaje (23,0 U y 24,9 U) presentaron anticuerpos anti-centrómero y anti-nucleares, con títulos 1/1280 y 1/640 respectivamente. Las mismas fueron analizadas para los marcadores de celiaquía y sólo una resultó positiva débil (21,8 U) para anti-Gliadina IgAII. La baja reactividad cruzada hallada con el ensayo de tamizaje htTG/DGP en presencia de otros autoanticuerpos permite concluir que dicha prueba constituye una herramienta de gran utilidad para la pesquisa de EC en pacientes con diferentes enfermedades autoinmunes.
The goal of this study was to show the presence of cross-reactivity screening test htTG/DGP for celiac disease (CD) with other autoantibodies present in high titers in different autoimmune diseases (AD). A cross-sectional study was performed for which 100 patients of both sexes (15 men, 85 women), aged between 4 and 86 years without CD who had different autoimmune pathologies were selected. To study the presence of CD, QUANTALite® (INOVA Diagnostics, USA): htTG/DGP Screen, htTG IgA and IgG, Gliadin IgAII and IgGII tests by ELISA were used. Other autoantibodies from AD were determined by indirect immunofluorescence and by electrochemiluminescence. Cross-reactivity with non-specific autoantibodies found in EC was 2.0%. The two positive samples of screening test (23,0 U and 24,9 U) had anti-centromere antibodies 1/1280 and anti-nuclear antibodies 1/640 respectively. They were analyzed for celiac disease markers and only one was weak positive (21,8 U) for anti-Gliadin IgAII. The low cross reactivity found with screening test htTG/DGP in the presence of other autoantibodies made it possible to conclude that this test is a useful tool for screening of CD in patients with different autoimmune diseases.
O objetivo deste trabalho foi estudar a presença de reatividade cruzada do teste de screening htTG/ DGP para a doença celíaca (DC) com outros autoanticorpos presentes em altos títulos em diferentes doenças autoimunes (DA). Foi realizado um estudo transversal para o qual foram selecionados 100 pacientes não-celíacos, de ambos os sexos (15 homens, 85 mulheres), com idades entre 4 e 86 anos que apresentavam diferentes patologias autoimunes (DA). Para estudar a presença de DC, realizaram-se por ELISA os ensaios QUANTALite® (INOVA Diagnostics, EUA): htTG/DGPScreen, htTG IgA e IgG, Gliadina IgAII e Gliadina IgGII por ELISA. Os autoanticorpos das outras DA foram determinados por imunofluorescência indireta e por eletroquimioluminescência. A reatividade cruzada encontrada com outros autoanticorpos não específicos de DC foi de 2,0%. As duas amostras positivas para o teste de screening (23,0 U e 24,9 U) apresentaram anticorpos anticentrômeros e antinucleares, com títulos 1/1280 e 1/640 respectivamente. Elas foram analisadas para os marcadores de doença celíaca e apenas uma resultou positiva fraca (21,8 U) para anti-Gliadina IgAII. A baixa reatividade cruzada encontrada com o teste de screening htTG/DGP em presença de outros autoanticorpos, permite concluir que este teste constitui um instrumento de grande utilidade para a pesquisa de doença celíaca em pacientes com diferentes doenças autoimunes.
Asunto(s)
Humanos , Masculino , Femenino , Preescolar , Niño , Adolescente , Adulto , Persona de Mediana Edad , Anciano , Anciano de 80 o más Años , Enfermedad Celíaca , Reactividad Cruzada , Autoanticuerpos/análisis , Enfermedades Autoinmunes , Cribado de Líquidos/métodosRESUMEN
The protozoan Leishmania braziliensis causes cutaneous leishmaniasis (CL) in endemic regions. In murine models, neutrophils (PMNs) are recruited to the site of infection soon after parasite inoculation. However, the roles of neutrophils during chronic infection and in human disease remain undefined. We hypothesized that neutrophils help maintain a systemic inflammatory state in subjects with CL. Lesion biopsies from all patients with CL tested contained neutrophils expressing HLA-DR, a molecule thought to be restricted to professional antigen-presenting cells. Although CL is a localized disease, a subset of patients with CL also had circulating neutrophils expressing HLA-DR and the costimulatory molecules CD80, CD86, and CD40. PMNs isolated from a low-density leukocyte blood fraction (LD-PMNs) contained a higher percentage of HLA-DR+ PMNs than did normal-density PMNs. In vitro coculture experiments suggested LD-PMNs do not suppress T cell responses, differentiating them from MDSCs. Flow-sorted HLA-DR+ PMNs morphologically resembled conventional PMNs, and they exhibited functional properties of PMNs. Compared with conventional PMNs, HLA-DR+ PMNs showed increased activation, degranulation, DHR123 oxidation, and phagocytic capacity. A few HLA-DR+ PMNs were observed in healthy subjects, and that proportion could be increased by incubation in either inflammatory cytokines or in plasma from a patient with CL. This was accompanied by an increase in PMN hladrb1 mRNA, suggesting a possible connection between neutrophil "priming" and up-regulation of HLA-DR. These data suggest that PMNs that are primed for activation and that also express surface markers of antigen-presenting cells emerge in the circulation and infected tissue lesions of patients with CL.
Asunto(s)
Antígenos HLA-DR/inmunología , Leishmaniasis Cutánea/inmunología , Leishmaniasis Cutánea/patología , Neutrófilos/inmunología , Neutrófilos/patología , Adulto , Brasil , Degranulación de la Célula , Diferenciación Celular , Proliferación Celular , Forma de la Célula , Reactividad Cruzada/inmunología , Gránulos Citoplasmáticos/metabolismo , Dextranos/metabolismo , Femenino , Humanos , Masculino , Fenotipo , Linfocitos T/inmunologíaRESUMEN
The aging process is accompanied by altered immune system functioning and an increased risk of infection. Dendritic cells (DCs) are antigen-presenting cells that play a key role in both adaptive and innate immunity, but how aging affects DCs and their influence on immunity has not been thoroughly established. Here we examined the function of conventional DCs (cDCs) in old mice after TLR7 stimulation, focusing on their ability to cross-prime CD8+ T cells. Using polyU, a synthetic ssRNA analog, as TLR7 ligand and OVA as an antigen (Ag) model, we found that cDCs from old mice have a poor ability to stimulate a CD8+ T cell-mediated cytotoxic response. cDCs from old mice exhibit alterations in Ag-processing machinery and TLR7 activation. Remarkably, CD8α+ cDCs from old mice have an impaired ability to activate naïve CD8+ T cells and, moreover, a lower capacity to mature and to process exogenous Ag. Taken together, our results suggest that immunosenescence impacts cDC function, affecting the activation of naïve CD8+ T cells and the generation of effector cytotoxic T cells.
Asunto(s)
Envejecimiento/inmunología , Presentación de Antígeno , Linfocitos T CD8-positivos/enzimología , Reactividad Cruzada/inmunología , Células Dendríticas/inmunología , Inmunidad Celular , Glicoproteínas de Membrana/inmunología , Receptor Toll-Like 7/inmunología , Animales , Antígenos/inmunología , Antígenos/farmacología , Reactividad Cruzada/efectos de los fármacos , Femenino , Ratones , Poli U/inmunología , Poli U/farmacologíaRESUMEN
Paracoccidioidomycosis is a systemic infection prevalent in Latin American countries. Disease develops after inhalation of Paracoccidioides brasiliensis conidia followed by an improper immune activation by the host leucocytes. Dendritic cells (DCs) are antigen-presenting cells with the unique ability to direct the adaptive immune response by the time of activation of naive T cells. This study was conducted to test whether extracts of P. brasiliensis would induce maturation of DCs. We found that DCs treated with extracts acquired an inflammatory phenotype and upon adoptive transfer conferred protection to infection. Interestingly, interleukin-10 production by CD8(+) T cells was ablated following DC transfer. Further analyses showed that lymphocytes from infected mice were high producers of interleukin-10, with CD8(+) T cells being the main source. Blockage of cross-presentation to CD8(+) T cells by modulated DCs abolished the protective effect of adoptive transfer. Collectively, our data show that adoptive transfer of P. brasiliensis-modulated DCs is an interesting approach for the control of infection in paracoccidioidomycosis.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Células Dendríticas/inmunología , Interleucina-10/biosíntesis , Paracoccidioides/inmunología , Paracoccidioidomicosis/inmunología , Paracoccidioidomicosis/prevención & control , Traslado Adoptivo , Animales , Antígenos Fúngicos/farmacología , Diferenciación Celular/inmunología , Reactividad Cruzada , Citocinas/biosíntesis , Células Dendríticas/citología , Células Dendríticas/microbiología , Femenino , Vacunas Fúngicas/inmunología , Vacunas Fúngicas/farmacología , Mediadores de Inflamación/metabolismo , Interleucina-10/antagonistas & inhibidores , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones NoqueadosRESUMEN
Salmonella persists for a long time in B cells; however, the mechanism(s) through which infected B cells avoid effector CD8 T cell responses has not been characterized. In this study, we show that Salmonella infects and survives within all B1 and B2 cell subpopulations. B cells are infected with a Salmonella typhimurium strain expressing an ovalbumin (OVA) peptide (SIINFEKL) to evaluate whether B cells process and present Salmonella antigens in the context of MHC-I molecules. Our data showed that OVA peptides are presented by MHC class I K(b)-restricted molecules and the presented antigen is generated through proteasomal degradation and vacuolar processing. In addition, Salmonella-infected B cells express co-stimulatory molecules such as CD40, CD80, and CD86 as well as inhibitory molecules such as PD-L1. Thus, the cross-presentation of Salmonella antigens and the expression of activation molecules suggest that infected B cells are able to prime and activate specific CD8(+) T cells. However, the Salmonella infection-stimulated expression of PD-L1 suggests that the PD-1/PD-L1 pathway may be involved in turning off the cytotoxic effector response during Salmonella persistent infection, thereby allowing B cells to become a reservoir for the bacteria.
Asunto(s)
Linfocitos B/inmunología , Linfocitos B/metabolismo , Antígeno B7-H1/genética , Regulación de la Expresión Génica , Infecciones por Salmonella/inmunología , Infecciones por Salmonella/metabolismo , Salmonella/inmunología , Animales , Presentación de Antígeno/inmunología , Antígenos Bacterianos/inmunología , Antígenos Bacterianos/metabolismo , Subgrupos de Linfocitos B/inmunología , Subgrupos de Linfocitos B/metabolismo , Subgrupos de Linfocitos B/microbiología , Linfocitos B/microbiología , Antígeno B7-H1/metabolismo , Transporte Biológico , Reactividad Cruzada/inmunología , Modelos Animales de Enfermedad , Antígenos de Histocompatibilidad Clase I/inmunología , Antígenos de Histocompatibilidad Clase I/metabolismo , Activación de Linfocitos/inmunología , Ratones , Salmonella typhimurium/inmunología , Vacuolas/inmunología , Vacuolas/metabolismoRESUMEN
Background: A secular trend towards a younger age of puberty onset has been reported in Chilean girls. Aim: To evaluate the age of onset of puberty and prevalence of early puberty in Chilean boys. Material and Methods: A pediatric endocrinologist examined 319 children attending schools in central Santiago. Pubertal development was assessed by testicular volume (TV) and genital inspection (GI) using Tanner graduation. Precocious and early puberty development was diagnosed if TV ≥ 4 ml or GI > stage 2 occurred in boys younger than 9 years and at 9-10 years of age, respectively. Results: Pubertal onset occurred at 10.2 ± 1.5 years according to TV and at 11.1 ± 1.6 years according to GI (p < 0.01). Before the age of nine, 15.2% of children had a VT ≥ 4 ml, 3% had genital changes in GI and only 3% had both changes simultaneously. Early puberty was observed in 23.8% of children according to TV and 9.5% according to GI. However, no child of less than 11 years old had a TV ≥ 4 ml, genital changes and pubic hair simultaneously. Late pubertal stages occurred at the same age according to both criteria used. Body mass index z score was not associated with the age of pubertal onset. Conclusions: Testicular enlargement occurs one year earlier than changes in genitalia according to inspection. Testicular growth, but not late stages of puberty, are occurring one year earlier than previously reported in Chile 10 years ago.
Asunto(s)
Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Presentación de Antígeno , /inmunología , /inmunología , Diferenciación Celular/inmunología , Reactividad Cruzada , Bacterias Gramnegativas/inmunología , Bacterias Grampositivas/inmunología , Inmunidad Adaptativa , /patología , /patología , Inmunidad Innata , Neutrófilos , Receptores de Antígenos de Linfocitos T gamma-delta/inmunologíaRESUMEN
Bidirectional cross-talk between the neuroendocrine and immune systems orchestrates immune responses in both physiologic and pathologic settings. In this study, we provide in vivo evidence of a critical role for the thyroid hormone triiodothyronine (T3) in controlling the maturation and antitumor functions of dendritic cells (DC). We used a thyroid hormone receptor (TR) ß mutant mouse (TRßPV) to establish the relevance of the T3-TRß system in vivo. In this model, TRß signaling endowed DCs with the ability to stimulate antigen-specific cytotoxic T-cell responses during tumor development. T3 binding to TRß increased DC viability and augmented DC migration to lymph nodes. Moreover, T3 stimulated the ability of DCs to cross-present antigens and to stimulate cytotoxic T-cell responses. In a B16-OVA mouse model of melanoma, vaccination with T3-stimulated DCs inhibited tumor growth and prolonged host survival, in part by promoting the generation of IFNγ-producing CD8(+) T cells. Overall, our results establish an adjuvant effect of T3-TRß signaling in DCs, suggesting an immediately translatable method to empower DC vaccination approaches for cancer immunotherapy.
Asunto(s)
Células Dendríticas/inmunología , Melanoma Experimental/inmunología , Receptores beta de Hormona Tiroidea/metabolismo , Triyodotironina/metabolismo , Animales , Linfocitos T CD8-positivos/inmunología , Movimiento Celular , Supervivencia Celular , Reactividad Cruzada , Citotoxicidad Inmunológica , Femenino , Inmunoterapia , Ganglios Linfáticos/inmunología , Melanoma Experimental/terapia , Ratones Endogámicos C57BL , Ratones TransgénicosRESUMEN
OBJECTIVES: To evaluate the possible effects of the introduction of the pneumococcal conjugate 10-valent vaccine schedule in the state of Parana on pneumococcal meningitis cases and to assess the distribution of serotypes among cases. METHOD: Cross-sectional study with retrospective data collection of cases of pneumococcal meningitis in the state of Paraná reported to Sistema de Informação de Agravos de Notificação (SINAN), from 1998 to 2011. A total of 1,339 cases of pneumococcal meningitis were analyzed; 1,205 cases from the pre-vaccine period (1998-2009) were compared to 134 cases from the post-vaccine period (2010-2011). Descriptive and comparative statistical analyses (chi-squared test and prevalence ratio) were performed using JMP 5.1.2 statistical software (JMP Statistical Discovery, North Carolina, USA) and EPI INFO 6 (Centers for Disease Control and Prevention, Georgia, EUA). RESULTS: There was a significant reduction in the mean rates of incidence and mortality in the general population. The analysis of cases in the pre- and post-vaccination periods in the age groups covered by vaccination (younger than 2 years) showed significant reductions in incidence rates (6.01 cases/100,000 to 2.49 cases/100,000 individuals) and mortality (1.85 cases/100,000 population to 0.47 cases/100,000 population), while the mean lethality rate did not change significantly. There was a significant reduction in cases whose serotypes are included in the vaccine (80.7% to 53.3%). CONCLUSION: Even after a short time of use, the 10-valent pneumococcal conjugate vaccine has already had a significant impact in reducing the incidence and mortality of meningitis cases among infants, as well as the reduction of cases whose serotypes are included in the vaccine.
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Meningitis Neumocócica/epidemiología , Vacunas Neumococicas/administración & dosificación , Adolescente , Brasil/epidemiología , Niño , Preescolar , Reactividad Cruzada/inmunología , Estudios Transversales , Humanos , Incidencia , Lactante , Meningitis Neumocócica/prevención & control , Prevalencia , Estudios Retrospectivos , Serotipificación , Vacunas Conjugadas/administración & dosificaciónRESUMEN
Cross-presentation (CP) is important for priming T cell responses to many viral, bacterial, and tumor antigens. Here, we designed two Ii mutants, based on evidence that the invariant chain (Ii, also named CD74) binds newly synthesized MHC class I molecules with the class II-associated invariant chain peptide (CLIP) region of Ii, which occupies the peptide-binding groove. Specifically, we designed (1) Ii-O257, which is a CLIP-substituted Ii chimer, in which OVA257-264 (SIINFEKL) was substituted for CLIP, and (2) Ii-, also named CT257, which is a C-terminal truncated form of Ii-O257 that contains the N-terminal flanking region of Ii. We immunized C57BL/6 mice with these recombinant proteins. Real-time PCR detected that mice immunized with either Ii-O257 or Ii-CT257 recombinant proteins exhibited increased IFN-γ mRNA expression (approximately 11-fold and 13-fold, respectively) and increased IL-2 mRNA expression (approximately 9-fold and 11-fold, respectively), compared to mice immunized with the OVA257-264 peptide. In vivo cytokine analysis showed that recombinant Ii proteins were highly efficient at activating T cells. Confocal microscopy and co-immunoprecipitation showed that the 2 Ii-OVA257-264 chimers are associated intracellularly with H-2K(b) molecules. Thus, Ii-CT257 (amino acids 1-89) binds stably to MHC class I with high affinity, indicating that it is a minimal functional fragment of the Ii immune vector. In conclusion, the N-terminal functional region of the Ii fusion protein containing CTL epitopes might prove to be useful for developing peptide or DNA vaccines that use CP as the main mechanism for CD8(+) T cell stimulation.
Asunto(s)
Antígenos de Diferenciación de Linfocitos B/química , Reactividad Cruzada , Epítopos/inmunología , Antígenos de Histocompatibilidad Clase II/química , Antígenos de Histocompatibilidad Clase I/inmunología , Linfocitos T Citotóxicos/inmunología , Animales , Antígenos de Diferenciación de Linfocitos B/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Interleucina-2/inmunología , Activación de Linfocitos/inmunología , Ratones , Péptidos/genética , Péptidos/inmunología , Proteínas Recombinantes/genética , Proteínas Recombinantes/inmunologíaRESUMEN
La alergia a los mariscos es una de las alergias alimentarias de mayor prevalencia en muchos países, especialmente la inducida por el consumo o contacto con los camarones. A varias especies de camarón se les conoce la capacidad de inducir alergias; sin embargo, el conjunto de alérgenos que producen no se conoce y pocos de ellos se han caracterizado completamente. Este trabajo se llevó a cabo para conocer los avances recientes en la caracterización de los alérgenos del camarón y su relación con alérgenos de otros artrópodos de importancia en las alergias. Se hace énfasis en la especie Litopenaeus vannamei , la de mayor consumo en Colombia. A los alérgenos de los camarones mayormente caracterizados se les nombra según la nomenclatura oficial, aunque se les conoce más por la función biológica asociada. La tropomiosina, el alérgeno principal y más estudiado en diferentes especies de camarón, participa en la reacción cruzada entre el camarón y otros artrópodos, como los ácaros domésticos. Los otros alérgenos caracterizados parecen contribuir poco en este tipo de reacción. El potencial alergénico del camarón L. vannamei no está completamente dilucidado y unos pocos de sus alérgenos se han caracterizado, mientras que otros recientemente identificados, como la hemocianina y las proteínas de unión a ácidos grasos, se empiezan a investigar. Los resultados preliminares sugieren que participan en la reacción cruzada entre el camarón y los ácaros. La caracterización molecular e inmunológica del conjunto de alérgenos presentes en el camarón, ayudaría a conocer mejor su papel alergénico.
Allergy to shellfish is one of the most prevalent food allergies in several countries, especially the one induced by consuming or having contact with shrimp. Several shrimp species are known to induce allergy diseases. However, the whole spectrum of allergens they contain is unknown and few of them have been completely characterized. This study was done in order to know the recent advances in the characterization of shrimp allergens and its relationship with allergens from other arthropods of importance in allergic diseases. We emphasize the species Litopenaeus vannamei , the most consumed shrimp in Colombia. Well characterized shrimp allergens are named following an official classification; nevertheless, they are better known according to the biological function associated with them. Tropomiosin, the main and most studied allergen in different shrimp species, is involved in crossreactivity among shrimp and other arthropods like domestic mites. The other characterized allergens seem to have a minor participation in this cross-reactivity. The allergenic potential of L. vannamei is not well known and few of its allergens have been characterized, whilst others that were recently identified such as the hemocyanin and the fatty acid binding proteins are beginning to be studied. Preliminary results suggest that these allergens are involved in the cross-reactivity between shrimp and domestic mites, which deserves further evaluation. The molecular and immunological characterization of all allergens present in shrimp would help understanding its allergenic role.
Asunto(s)
Alérgenos , Alergia e Inmunología , Inmunoglobulina E , Reactividad CruzadaRESUMEN
Lumazine synthase from Brucella spp. (BLS) is a highly immunogenic decameric protein. It is possible to insert foreign peptides or proteins at its ten-amino acid termini. These chimeras elicit systemic and oral immunity without adjuvants, which are commonly needed in the formulation of subunit-based vaccines. Here, we show that BLS induces the cross presentation of a covalently attached peptide OVA(257-264) and a specific cytotoxic response to this peptide in the absence of adjuvants. Unlike other subunit-based vaccines, this chimera induces rapid activation of CTLs and a specific cytotoxic response, making this polymeric protein an ideal antigen carrier for vaccine development. Adoptive transfer of transgenic OT-I T cells revealed efficient cross presentation of BLS-OVA(257-264)in vivo. BLS-OVA(257-264) immunization induced the proliferation of OVA(257-264)-specific CD8+ lymphocytes and also increased the percentage of OVA(257-264)-specific CD8+ cells expressing the early activation marker CD69; after 5 days, the percentage of OVA(257-264)-specific CD8+ cells expressing high levels of CD44 increased. This cell subpopulation showed decreased expression of IL-7Rα, indicating that BLS-OVA(257-264) induced the generation of CD8+ effector cells. BLS-OVA(257-264) was cross presented in vitro independently of the presence of a functional TLR4 in the DCs. Finally, we show that immunization of wild type mice with the chimera BLS-OVA(257-264) without adjuvants induced a strong OVA(257-264)-specific effector cytotoxic response. This cytotoxicity is dependent on TLR4 as is not induced in mice lacking a functional receptor. These data show that TLR4 signaling is necessary for the induction of a cytotoxic response but not for antigen cross presentation.