RESUMO
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.
Assuntos
Apresentação de Antígeno , Apresentação Cruzada , Células Dendríticas , Hemeproteínas , Hemeproteínas/imunologia , Apresentação Cruzada/imunologia , Animais , Células Dendríticas/imunologia , Camundongos , Nanopartículas/química , Humanos , Malária/imunologia , Lectinas Tipo C/metabolismo , Lectinas Tipo C/imunologia , Ovalbumina/imunologiaRESUMO
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.
Assuntos
Apresentação de Antígeno/imunologia , Chlamydia trachomatis/imunologia , Apresentação Cruzada/imunologia , Células Dendríticas/imunologia , Células Dendríticas/microbiologia , Antígenos de Histocompatibilidade Classe I/imunologia , Animais , Células da Medula Óssea/imunologia , Linhagem Celular , Chlamydia trachomatis/patogenicidade , Endocitose , Camundongos , Camundongos Endogâmicos C57BL , Transporte ProteicoRESUMO
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.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Células Dendríticas/imunologia , Memória Imunológica/imunologia , Melanoma/imunologia , Pele/imunologia , Animais , Antígenos/imunologia , Movimento Celular/imunologia , Apresentação Cruzada/imunologia , Humanos , Linfonodos/imunologia , Melanoma/patologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pele/citologia , Linfócitos T Citotóxicos/imunologiaRESUMO
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.
Assuntos
Brucelose/imunologia , Receptores ErbB/imunologia , Evasão da Resposta Imune/imunologia , Monócitos/imunologia , RNA Bacteriano/imunologia , Receptor 8 Toll-Like/imunologia , Animais , Brucella abortus/imunologia , Apresentação Cruzada/imunologia , Regulação para Baixo , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Antígenos de Histocompatibilidade Classe I/biossíntese , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Monócitos/microbiologia , Transdução de Sinais/imunologiaRESUMO
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.
Assuntos
Vacinas Anticâncer/imunologia , Células Dendríticas/imunologia , Neoplasias/etiologia , Neoplasias/patologia , Papillomaviridae/imunologia , Infecções por Papillomavirus/complicações , Infecções por Papillomavirus/imunologia , Proteínas do Envelope Viral/imunologia , Animais , Apresentação de Antígeno/imunologia , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Linhagem Celular Tumoral , Apresentação Cruzada/imunologia , Células Dendríticas/metabolismo , Feminino , Humanos , Imunização , Memória Imunológica , Camundongos , Camundongos Knockout , Neoplasias/terapia , Proteínas E7 de Papillomavirus/imunologia , Poli I-C , Especificidade do Receptor de Antígeno de Linfócitos T , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismoRESUMO
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.
Assuntos
Infecções por HIV/imunologia , HIV-1/imunologia , Leucócitos Mononucleares/imunologia , Transcriptoma/imunologia , Terapia Antirretroviral de Alta Atividade , Antitrombina III/genética , Antitrombina III/imunologia , Antivirais/uso terapêutico , Brasil , Contagem de Linfócito CD4 , Quimiocinas/genética , Quimiocinas/imunologia , Estudos de Coortes , Apresentação Cruzada/imunologia , Citocinas/genética , Citocinas/imunologia , Perfilação da Expressão Gênica/métodos , Infecções por HIV/tratamento farmacológico , Infecções por HIV/genética , Sobreviventes de Longo Prazo ao HIV , HIV-1/efeitos dos fármacos , Antígenos HLA-B/imunologia , Interações Hospedeiro-Patógeno/efeitos dos fármacos , Interações Hospedeiro-Patógeno/imunologia , Humanos , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcriptoma/efeitos dos fármacosRESUMO
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.
Assuntos
Antígenos HLA-DR/imunologia , Leishmaniose Cutânea/imunologia , Leishmaniose Cutânea/patologia , Neutrófilos/imunologia , Neutrófilos/patologia , Adulto , Brasil , Degranulação Celular , Diferenciação Celular , Proliferação de Células , Forma Celular , Apresentação Cruzada/imunologia , Grânulos Citoplasmáticos/metabolismo , Dextranos/metabolismo , Feminino , Humanos , Masculino , Fenótipo , Linfócitos T/imunologiaRESUMO
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.
Assuntos
Envelhecimento/imunologia , Apresentação de Antígeno , Linfócitos T CD8-Positivos/enzimologia , Apresentação Cruzada/imunologia , Células Dendríticas/imunologia , Imunidade Celular , Glicoproteínas de Membrana/imunologia , Receptor 7 Toll-Like/imunologia , Animais , Antígenos/imunologia , Antígenos/farmacologia , Apresentação Cruzada/efeitos dos fármacos , Feminino , Camundongos , Poli U/imunologia , Poli U/farmacologiaRESUMO
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.
Assuntos
Linfócitos B/imunologia , Linfócitos B/metabolismo , Antígeno B7-H1/genética , Regulação da Expressão Gênica , Infecções por Salmonella/imunologia , Infecções por Salmonella/metabolismo , Salmonella/imunologia , Animais , Apresentação de Antígeno/imunologia , Antígenos de Bactérias/imunologia , Antígenos de Bactérias/metabolismo , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/metabolismo , Subpopulações de Linfócitos B/microbiologia , Linfócitos B/microbiologia , Antígeno B7-H1/metabolismo , Transporte Biológico , Apresentação Cruzada/imunologia , Modelos Animais de Doenças , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Ativação Linfocitária/imunologia , Camundongos , Salmonella typhimurium/imunologia , Vacúolos/imunologia , Vacúolos/metabolismoRESUMO
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.