RESUMO
Humans are exposed every day to innumerable external stimuli, both environmental and microbial. Immunological memory recalls each specific stimulus and mounts a secondary response that is faster and of a larger magnitude than the primary response; this process constitutes the basis for vaccine development. The COVID-19 pandemic offers a unique opportunity to study the development of immune memory against an emergent microorganism. Memory T cells have an important role in the resolution of COVID-19, and they are key pillars of immunological memory. In this review, we summarize the main findings regarding anti-SARS-CoV-2 memory T cells after infection, after vaccination, and after the combination of these two events ("hybrid immunity"), and analyze how these cells can contribute to long-term protection against the infection with SARS-CoV-2 variants.
Los humanos se exponen cada día a innumerables estímulos externos, tanto ambientales como microbianos. La memoria inmunológica registra de manera específica un estímulo y articula una respuesta secundaria más rápida y de mayor magnitud que la respuesta primaria; este proceso constituye la base del desarrollo de vacunas. La pandemia de COVID-19 ofreció la oportunidad de estudiar el desarrollo de la memoria inmunológica contra un microorganismo emergente. Las células T de memoria tienen un papel importante en la resolución de COVID-19 y son pilares importantes de la memoria inmunológica. En esta revisión se resumen los principales hallazgos de la respuesta de las células T de memoria contra la infección por SARS-CoV-2, a la vacunación o a la combinación de ambos procesos ("inmunidad híbrida"), y se discute cómo estas células pueden contribuir a la protección a largo plazo contra distintas variantes del virus.
Assuntos
Vacinas contra COVID-19 , COVID-19 , Memória Imunológica , Células T de Memória , SARS-CoV-2 , Humanos , COVID-19/imunologia , COVID-19/prevenção & controle , Memória Imunológica/imunologia , Células T de Memória/imunologia , Vacinas contra COVID-19/imunologia , SARS-CoV-2/imunologiaRESUMO
Pathogenic bacteria have several mechanisms to evade the host's immune response and achieve an efficient infection. Bacterial extracellular vesicles (EVs) are a relevant cellular communication mechanism, since they can interact with other bacterial cells and with host cells. In this review, we focus on the EVs produced by some World Health Organization (WHO) priority Gram-negative and Gram-positive pathogenic bacteria; by spore-producing bacteria; by Mycobacterium tuberculosis (a bacteria with a complex cell wall); and by Treponema pallidum (a bacteria without lipopolysaccharide). We describe the classification and the general properties of bacterial EVs, their role during bacterial infections and their effects on the host immune response. Bacterial EVs contain pathogen-associated molecular patterns that activate innate immune receptors, which leads to cytokine production and inflammation, but they also contain antigens that induce the activation of B and T cell responses. Understanding the many effects of bacterial EVs on the host's immune response can yield new insights on the pathogenesis of clinically important infections, but it can also lead to the development of EV-based diagnostic and therapeutic strategies. In addition, since EVs are efficient activators of both the innate and the adaptive immune responses, they constitute a promising platform for vaccine development.
Assuntos
Vesículas Extracelulares , Vesículas Extracelulares/imunologia , Vesículas Extracelulares/metabolismo , Humanos , Animais , Imunidade Inata , Interações Hospedeiro-Patógeno/imunologia , Infecções Bacterianas/imunologia , Infecções Bacterianas/microbiologia , Bactérias/imunologiaRESUMO
Background: Upper respiratory tract infections (URIs) are very common in the pediatric population. Most of these infections are mild, but due to their chronicity they affect quality of life (QoL), in addition to high costs for medical care. The use of bacterial extracts (BE) that stimulate general immunity can reduce its frequency and improve the QoL of the patient. Objective: Evaluate the effectiveness of a BE in the prevention of ARVI in children from 1 to 6 years of age. Methods: Children between the ages of 1 and 6 years, with a diagnosis of RAVI, were randomized into 3 different groups, with medical follow-up at 6 and 12 weeks after the start. The EB was administered with different doses to each group. An ANOVA test with a Tukey post hoc is used for multiple comparisons (maximum type I error of 0.05). Results: 33 children (12 girls) with a mean age of 3.11 years were included. The average frequency of RAVI prior to treatment was 2.2 events/month and 0.9 and 0.4 events/month at 6 and 12 weeks, respectively. The IVARS were reduced by 76.9% at 3 months of treatment. (Graph). No adverse effects were reported. Conclusions: BE is safe and effective in reducing the frequency of RAVI in children, in agreement with the literature. There is not enough published scientific evidence, but the BE seems to have an application in the prevention and treatment of RAVI. Sublingual administration is comfortable in this age group.
Antecedentes: Las infecciones de vías aéreas superiores (IVASR) son muy frecuentes en la población pediátrica. La mayoría de estas infecciones son leves, pero por la cronicidad afectan la calidad de vida (CdV), además de elevados costos por la atención médica. El uso de extractos bacterianos (EB) que estimulen la inmunidad general pueden reducir su frecuencia y mejorar la CdV del paciente. Objetivo: Evaluar la efectividad de un EB en la prevención de IVASR en niños de 1 a 6 años. Métodos: Se aleatorizaron niños entre 1 y 6 años, con diagnóstico IVASR en 3 grupos distintos, seguimiento médico a las 6 y 12 semanas tras el inicio. El EB se administró con dosis distintas a cada grupo. Se utiliza una prueba de ANOVA con un post hoc Tukey para comparaciones múltiples (error tipo I máximo de 0.05). Resultados: Se incluyeron 33 niños (12 niñas) con una media de edad de 3.11 años. La frecuencia de IVASR previo al tratamiento en promedio fue de 2.2 eventos/mes y de 0.9 y de 0.4 eventos/mes a las 6 y 12 semanas respectivamente. La IVARS se redujeron un 76.9% a los 3 meses de tratamiento. (Gráfica). No se reportaron efectos adversos. Conclusiones: El EB es seguro y efectivo en disminuir la frecuencia de IVASR en niños en concordancia con la literatura. No hay suficiente evidencia científica publicada pero el EB parece tener aplicación en la prevención y tratamiento de las IVASR. La administración sublingual es cómoda en este grupo etario.
Assuntos
Metenamina , Qualidade de Vida , Feminino , Humanos , Criança , Recém-Nascido , Lactente , Pré-Escolar , Administração Sublingual , Azul de Metileno , Estudos RetrospectivosRESUMO
Tuberculosis remains one of the leading public health problems in the world. The mechanisms that lead to the activation of the immune response against Mycobacterium tuberculosis have been extensively studied, with a focus on the role of cytokines as the main signals for immune cell communication. However, less is known about the role of other signals, such as extracellular vesicles, in the communication between immune cells, particularly during the activation of the adaptive immune response. In this study, we determined that extracellular vesicles released by human neutrophils infected with M. tuberculosis contained several host proteins that are ectosome markers. In addition, we demonstrated that extracellular vesicles released by human neutrophils infected with M. tuberculosis released after only 30 min of infection carried mycobacterial antigens and pathogen-associated molecular patterns, and we identified 15 mycobacterial proteins that were consistently found in high concentrations in extracellular vesicles released by human neutrophils infected with M. tuberculosis; these proteins contain epitopes for CD4 T-cell activation. We found that extracellular vesicles released by human neutrophils infected with M. tuberculosis increased the expression of the costimulatory molecule CD80 and of the coinhibitory molecule PD-L1 on immature monocyte-derived dendritic cells. We also found that immature and mature dendritic cells treated with extracellular vesicles released by human neutrophils infected with M. tuberculosis were able to induce IFN-γ production by autologous M. tuberculosis antigen-specific CD4 T cells, indicating that these extracellular vesicles acted as antigen carriers and transferred mycobacterial proteins to the antigen-presenting cells. Our results provide evidence that extracellular vesicles released by human neutrophils infected with M. tuberculosis participate in the activation of the adaptive immune response against M. tuberculosis.
Assuntos
Vesículas Extracelulares , Mycobacterium tuberculosis , Tuberculose , Humanos , Células Th1 , Neutrófilos , Monócitos , Células DendríticasRESUMO
The clinical presentation of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), ranges between mild respiratory symptoms and a severe disease that shares many of the features of sepsis. Sepsis is a deregulated response to infection that causes life-threatening organ failure. During sepsis, the intestinal epithelial cells are affected, causing an increase in intestinal permeability and allowing microbial translocation from the intestine to the circulation, which exacerbates the inflammatory response. Here we studied patients with moderate, severe and critical COVID-19 by measuring a panel of molecules representative of the innate and adaptive immune responses to SARS-CoV-2, which also reflect the presence of systemic inflammation and the state of the intestinal barrier. We found that non-surviving COVID-19 patients had higher levels of low-affinity anti-RBD IgA antibodies than surviving patients, which may be a response to increased microbial translocation. We identified sFas and granulysin, in addition to IL-6 and IL-10, as possible early biomarkers with high sensitivity (>73 %) and specificity (>51 %) to discriminate between surviving and non-surviving COVID-19 patients. Finally, we found that the microbial metabolite d-lactate and the tight junction regulator zonulin were increased in the serum of patients with severe COVID-19 and in COVID-19 patients with secondary infections, suggesting that increased intestinal permeability may be a source of secondary infections in these patients. COVID-19 patients with secondary infections had higher disease severity and mortality than patients without these infections, indicating that intestinal permeability markers could provide complementary information to the serum cytokines for the early identification of COVID-19 patients with a high risk of a fatal outcome.
Assuntos
COVID-19 , Coinfecção , Sepse , Humanos , COVID-19/diagnóstico , SARS-CoV-2 , Interleucina-6 , Interleucina-10 , Permeabilidade , Biomarcadores , IntestinosRESUMO
Liposomes are artificial models of cellular membranes that are used as delivery systems for genes, drugs and protein antigens. We have previously used them to study the antigenic properties of their phospholipids. Here, we used them to induce the production of IgG anti-non-bilayer phospholipid arrangements (NPAs) antibodies in mice; these antibodies cause cell lysis and trigger a lupus-like disease in mice. We studied the mechanisms that lead to the production of these antibodies, and provide evidence that NK1.1+, CD4+ T cells respond to NPA-bearing liposomes and deliver the help required for specific B cell activation and antibody class-switching to IgG. We found increased numbers of IL-4-producing NK1.1+, CD4+ T cells in the secondary lymphoid organs of mice administered with NPAs, and these cells also expressed CD40L, which is required for B cell activation. Additionally, we isolated and purified NK1.1+, CD4+ T cells from spleens and determined that they over-expressed 40 genes, which are key players in inflammatory processes and B cell stimulation and have TRAF6 and UNC39B1 as key nodes in their network. These results show that liposomes are membrane models that can be used to analyze the immunogenicity of lipids.
RESUMO
Most individuals infected with Mycobacterium tuberculosis (Mtb) have latent tuberculosis (TB), which can be diagnosed with tests (such as the QuantiFERON-TB Gold test [QFT]) that detect the production of IFN-γ by memory T cells in response to the Mtb-specific antigens 6 kDa early secretory antigenic target EsxA (Rv3875) (ESAT-6), 10 kDa culture filtrate antigen EsxB (Rv3874) (CFP-10), and Mtb antigen of 7.7 kDa (Rv2654c) (TB7.7). However, the immunological mechanisms that determine if an individual will develop latent or active TB remain incompletely understood. Here we compared the response of innate and adaptive peripheral blood lymphocytes from healthy individuals without Mtb infection (QFT negative) and from individuals with latent (QFT positive) or active TB infection, to determine the characteristics of these cells that correlate with each condition. In active TB patients, the levels of IFN-γ that were produced in response to Mtb-specific antigens had high positive correlations with IL-1ß, TNF-α, MCP-1, IL-6, IL-12p70, and IL-23, while the proinflammatory cytokines had high positive correlations between themselves and with IL-12p70 and IL-23. These correlations were not observed in QFT-negative or QFT-positive healthy volunteers. Activation with Mtb-soluble extract (a mixture of Mtb antigens and pathogen-associated molecular patterns [PAMPs]) increased the percentage of IFN-γ-/IL-17-producing NK cells and of IL-17-producing innate lymphoid cell 3 (ILC3) in the peripheral blood of active TB patients, but not of QFT-negative or QFT-positive healthy volunteers. Thus, active TB patients have both adaptive and innate lymphocyte subsets that produce characteristic cytokine profiles in response to Mtb-specific antigens or PAMPs. These profiles are not observed in uninfected individuals or in individuals with latent TB, suggesting that they are a response to active TB infection.
Assuntos
Tuberculose Latente , Mycobacterium tuberculosis , Tuberculose , Antígenos de Bactérias , Citocinas , Humanos , Imunidade Inata , Interleucina-17 , Interleucina-23 , Interleucina-6 , Linfócitos , Moléculas com Motivos Associados a Patógenos , Fator de Necrose Tumoral alfaRESUMO
Acute systemic inflammation can lead to life-threatening organ dysfunction. In patients with sepsis, systemic inflammation is triggered in response to infection, but in other patients, a systemic inflammatory response syndrome (SIRS) is triggered by non-infectious events. IL-6 is a major mediator of inflammation, including systemic inflammatory responses. In homeostatic conditions, when IL-6 engages its membrane-bound receptor on myeloid cells, it promotes pro-inflammatory cytokine production, phagocytosis, and cell migration. However, under non-physiologic conditions, such as SIRS and sepsis, leucocyte dysfunction could modify the response of these cells to IL-6. So, our aim was to evaluate the response to IL-6 of monocytes from patients diagnosed with SIRS or sepsis. We observed that monocytes from patients with SIRS, but not from patients with sepsis, produced significantly more TNF-α than monocytes from healthy volunteers, after stimulation with IL-6. Monocytes from SIRS patients had a significantly increased baseline phosphorylation of the p65 subunit of NF-κB, with no differences in STAT3 phosphorylation or SOCS3 levels, compared with monocytes from septic patients, and this increased phosphorylation was maintained during the IL-6 activation. We found no significant differences in the expression levels of the membrane-bound IL-6 receptor, or the serum levels of IL-6, soluble IL-6 receptor, or soluble gp130, between patients with SIRS and patients with sepsis. Our results suggest that, during systemic inflammation in the absence of infection, IL-6 promotes TNF-α production by activating NF-κB, and not the canonical STAT3 pathway.
Assuntos
Interleucina-6 , Sepse , Síndrome de Resposta Inflamatória Sistêmica , Fator de Necrose Tumoral alfa , Humanos , Inflamação , Interleucina-6/farmacologia , Monócitos , NF-kappa B , Receptores de Interleucina-6 , Sepse/metabolismo , Síndrome de Resposta Inflamatória Sistêmica/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Chagas disease is caused by Trypanosoma cruzi and represents a major public health problem, which is endemic in Latin America and emerging in the rest of the world. The two drugs that are currently available for its treatment, Benznidazole and Nifurtimox, are partially effective in the chronic phase of the disease. In this study, we designed and synthesized the benzyl ester of N-isopropyl oxamic acid (B-NIPOx), which is a non-polar molecule that crosses cell membranes. B-NIPOx is cleaved inside the parasite by carboxylesterases, releasing benzyl alcohol (a molecule with antimicrobial activity), and NIPOx, which is an inhibitor of α-hydroxy acid dehydrogenase isozyme II (HADH-II), a key enzyme in T. cruzi metabolism. We evaluated B-NIPOx cytotoxicity, its toxicity in mice, and its inhibitory activity on purified HADH-II and on T. cruzi homogenates. We then evaluated the trypanocidal activity of B-NIPOx in vitro and in vivo and its effect in the intestine of T. cruzi-infected mice. We found that B-NIPOx had higher trypanocidal activity on epimastigotes and trypomastigotes than Benznidazole and Nifurtimox, that it was more effective to reduce blood parasitemia and amastigote nests in infected mice, and that, in contrast to the reference drugs, it prevented the development of Chagasic enteropathy.
Assuntos
Doença de Chagas , Nitroimidazóis , Tripanossomicidas , Trypanosoma cruzi , Camundongos , Animais , Nifurtimox/farmacologia , Nifurtimox/uso terapêutico , Tripanossomicidas/farmacologia , Tripanossomicidas/uso terapêutico , Doença de Chagas/tratamento farmacológico , Doença de Chagas/parasitologia , Nitroimidazóis/farmacologia , Nitroimidazóis/uso terapêutico , IsoenzimasRESUMO
Valproic acid (VPA) is a drug commonly used for epileptic seizure control. Recently, it has been shown that VPA alters the activation of several immune cells, including Natural Killer (NK) cells, which play an important role in the containment of viruses and intracellular bacteria. Although VPA can increase susceptibility to extracellular pathogens, it is unknown whether the suppressor effect of VPA could affect the course of intracellular bacterial infection. This study aimed to evaluate the role of VPA during Listeria monocytogenes (L.m) infection, and whether NK cell activation was affected. We found that VPA significantly augmented mortality in L.m infected mice. This effect was associated with increased bacterial load in the spleen, liver, and blood. Concurrently, decreased levels of IFN-γ in serum and lower splenic indexes were observed. Moreover, in vitro analysis showed that VPA treatment decreased the frequency of IFN-γ-producing NK cells within L.m infected splenocytes. Similarly, VPA inhibited the production of IFN-γ by NK cells stimulated with IL-12 and IL-18, which is a crucial system for early IFN-γ production in listeriosis. Finally, VPA decreased the phosphorylation of STAT4, p65, and p38, without affecting the expression of IL-12 and IL-18 receptors. Altogether, our results indicate that VPA increases the susceptibility to Listeria monocytogenes infection and suggest that NK cell is one of the main targets of VPA, but further work is needed to ascertain this effect.
Assuntos
Interferon gama/metabolismo , Células Matadoras Naturais/imunologia , Listeria monocytogenes/fisiologia , Listeriose/imunologia , Ácido Valproico/metabolismo , Animais , Células Cultivadas , Modelos Animais de Doenças , Suscetibilidade a Doenças , Feminino , Humanos , Imunomodulação , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos BALB C , Fator de Transcrição STAT4/metabolismo , Transdução de Sinais , Ácido Valproico/imunologiaRESUMO
Mast cell activation through the high-affinity IgE receptor (FcεRI) plays a central role in allergic reactions. FcεRI-mediated activation triggers multiple signaling pathways leading to degranulation and synthesis of different inflammatory mediators. IgE-mediated mast cell activation can be modulated by different molecules, including several drugs. Herein, we investigated the immunomodulatory activity of the histone deacetylase inhibitor valproic acid (VPA) on IgE-mediated mast cell activation. To this end, bone marrow-derived mast cells (BMMC) were sensitized with IgE and treated with VPA followed by FcεRI cross-linking. The results indicated that VPA reduced mast cell IgE-dependent degranulation and cytokine release. VPA also induced a significant reduction in the cell surface expression of FcεRI and CD117, but not other mast cell surface molecules. Interestingly, VPA treatment inhibited the phosphorylation of PLCγ2, a key signaling molecule involved in IgE-mediated degranulation and cytokine secretion. However, VPA did not affect the phosphorylation of other key components of the FcεRI signaling pathway, such as Syk, Akt, ERK1/2, or p38. Altogether, our data demonstrate that VPA affects PLCγ2 phosphorylation, which in turn decreases IgE-mediated mast cell activation. These results suggest that VPA might be a key modulator of allergic reactions and might be a promising therapeutic candidate.
Assuntos
Inibidores de Histona Desacetilases/farmacologia , Imunoglobulina E/imunologia , Mastócitos/efeitos dos fármacos , Fosfolipase C gama/antagonistas & inibidores , Receptores de IgE/efeitos dos fármacos , Ácido Valproico/farmacologia , Animais , Degranulação Celular/efeitos dos fármacos , Regulação para Baixo/efeitos dos fármacos , Interleucina-13/metabolismo , Interleucina-6/metabolismo , Mastócitos/citologia , Camundongos , Fosfolipase C gama/fisiologia , Receptores de IgE/biossíntese , Receptores de IgE/genética , Fator de Necrose Tumoral alfa/metabolismoRESUMO
BACKGROUND: Tuberculosis is the leading cause of death by an infectious microorganism worldwide. Conventional treatment lasts at least six months and has adverse effects; therefore, it is important to find therapeutic alternatives that reduce the bacterial load and may reduce the treatment duration. The immune response against tuberculosis can be modulated by several mechanisms, including extracellular vesicles (EVs), which are nano-sized membrane-bound structures that constitute an efficient communication mechanism among immune cells. METHODS: The EVs released by the J774A.1 mouse macrophage cell line, both spontaneously (S-EV) and after infection with Mycobacterium tuberculosis H37Rv (Mtb-EV), were purified by ultra-centrifugation and size-exclusion chromatography. The size distribution and chemical composition of these EVs were evaluated, and their effect on the bacterial load and the production of cytokines was determined in both in vitro and in vivo models of M. tuberculosis infection. RESULTS: Mtb-EV are larger than S-EV, they contain M. tuberculosis-specific antigens (not detected in EVs released from M. fortuitum-infected J774A.1 cells) and are rich in phosphatidylserine, present in their outer membrane layer. S-EV, but not Mtb-EV, reduced the bacterial load and the production of MCP-1 and TNF-α in M. tuberculosis-infected macrophages, and these effects were reversed when phosphatidylserine was blocked with annexin V. Both S-EV and Mtb-EV significantly reduced the lung bacterial load in mice infected with M. tuberculosis after 60 days of treatment, but they had no effect on survival or on the lung pneumonic area of these mice. CONCLUSION: J774A.1 macrophages infected with M. tuberculosis H37Rv released EVs that differed in size and phosphatidylserine content from spontaneously released EVs, and these EVs also had different biological effects: S-EV reduced the mycobacterial load and the cytokine production in vitro (through a phosphatidylserine-dependent mechanism), while both EVs reduced the lung bacterial load in vivo. These results are the basis for further experiments to evaluate whether EVs improve the efficiency of the conventional treatment for tuberculosis.
Assuntos
Vesículas Extracelulares/metabolismo , Macrófagos/metabolismo , Macrófagos/microbiologia , Tuberculose/terapia , Animais , Carga Bacteriana , Linhagem Celular , Citocinas/metabolismo , Modelos Animais de Doenças , Vesículas Extracelulares/química , Vesículas Extracelulares/transplante , Masculino , Camundongos Endogâmicos BALB C , Mycobacterium tuberculosis/patogenicidade , Tuberculose/microbiologiaRESUMO
Tuberculosis is one of the leading causes of mortality worldwide, it is caused by Mycobacterium tuberculosis (Mtb), a bacteria that employs several strategies to evade the host immune response. For instance, Mtb interferes with the overexpression of class II transactivator (CIITA) in macrophages exposed to IFN-γ by inhibiting histone acetylation at its promoter, which can be reverted by the histone deacetylase inhibitor (HDACi) sodium butyrate. In this work, we evaluated whether a different HDACi, valproic acid (VPA), could revert the inhibition of gene expression induced by Mtb. J774 macrophages treated with VPA and IFN-γ unexpectedly induced a higher expression of the inducible nitric oxide synthase and a higher production of nitric oxide when exposed to the 19â¯kDa lipoprotein of Mtb or the whole bacteria. However, VPA was unable to revert the inhibition of CIITA expression induced by the 19â¯kDa lipoprotein of Mtb. Finally, macrophages infected with Mtb and treated with VPA and IFN-γ showed a significant reduction in intracellular bacteria. Our findings suggest a new therapeutic potential of VPA for the treatment of tuberculosis.
Assuntos
Interferon gama/imunologia , Macrófagos/metabolismo , Mycobacterium tuberculosis/efeitos dos fármacos , Óxido Nítrico/biossíntese , Ácido Valproico/farmacologia , Animais , Antituberculosos/farmacologia , Células Cultivadas , Avaliação Pré-Clínica de Medicamentos/métodos , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Macrófagos/microbiologia , Camundongos , Mycobacterium tuberculosis/isolamento & purificação , Mycobacterium tuberculosis/metabolismo , Óxido Nítrico Sintase Tipo II/biossíntese , Óxido Nítrico Sintase Tipo II/genéticaRESUMO
Salmonella enterica infections remain a challenging health issue, causing significant morbidity and mortality worldwide. Current vaccines against typhoid fever display moderate efficacy whilst no licensed vaccines are available for paratyphoid fever or invasive non-typhoidal salmonellosis. Therefore, there is an urgent need to develop high efficacy broad-spectrum vaccines that can protect against typhoidal and non-typhoidal Salmonella. The Salmonella outer membrane porins OmpC and OmpF, have been shown to be highly immunogenic antigens, efficiently eliciting protective antibody, and cellular immunity. Furthermore, enterobacterial porins, particularly the OmpC, have a high degree of homology in terms of sequence and structure, thus making them a suitable vaccine candidate. However, the degree of the amino acid conservation of OmpC among typhoidal and non-typhoidal Salmonella serovars is currently unknown. Here we used a bioinformatical analysis to classify the typhoidal and non-typhoidal Salmonella OmpC amino acid sequences into different clades independently of their serological classification. Further, our analysis determined that the porin OmpC contains various amino acid sequences that are highly conserved among both typhoidal and non-typhoidal Salmonella serovars. Critically, some of these highly conserved sequences were located in the transmembrane ß-sheet within the porin ß-barrel and have immunogenic potential for binding to MHC-II molecules, making them suitable candidates for a broad-spectrum Salmonella vaccine. Collectively, these findings suggest that these highly conserved sequences may be used for the rational design of an effective broad-spectrum vaccine against Salmonella.
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Proteínas de Bactérias/genética , Porinas/genética , Salmonella/genética , Sequência de Aminoácidos , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Sequência Conservada , Humanos , Filogenia , Porinas/química , Porinas/metabolismo , Conformação Proteica em alfa-Hélice , Salmonella/química , Salmonella/classificação , Salmonella/metabolismo , Infecções por Salmonella/microbiologia , Salmonella typhi/química , Salmonella typhi/classificação , Salmonella typhi/genética , Salmonella typhi/metabolismo , Alinhamento de Sequência , Febre Tifoide/microbiologiaRESUMO
Tuberculosis is an infectious disease caused by Mycobacterium tuberculosis (Mtb). In the lungs, macrophages and neutrophils are the first immune cells that have contact with the infecting mycobacteria. Neutrophils are phagocytic cells that kill microorganisms through several mechanisms, which include the lytic enzymes and antimicrobial peptides that are found in their lysosomes, and the production of reactive oxygen species. Neutrophils also release extracellular vesicles (EVs) (100-1,000 nm in diameter) to the extracellular milieu; these EVs consist of a lipid bilayer surrounding a hydrophilic core and participate in intercellular communication. We previously demonstrated that human neutrophils infected in vitro with Mtb H37Rv release EVs (EV-TB), but the effect of these EVs on other cells relevant for the control of Mtb infection, such as macrophages, has not been completely analyzed. In this study, we characterized the EVs produced by non-stimulated human neutrophils (EV-NS), and the EVs produced by neutrophils stimulated with an activator (PMA), a peptide derived from bacterial proteins (fMLF) or Mtb, and observed that the four EVs differed in their size. Ligands for toll-like receptor (TLR) 2/6 were detected in EV-TB, and these EVs favored a modest increase in the expression of the co-stimulatory molecules CD80, a higher expression of CD86, and the production of higher amounts of TNF-α and IL-6, and of lower amounts of TGF-ß, in autologous human macrophages, compared with the other EVs. EV-TB reduced the amount of intracellular Mtb in macrophages, and increased superoxide anion production in these cells. TLR2/6 ligation and superoxide anion production are known inducers of autophagy; accordingly, we found that EV-TB induced higher expression of the autophagy-related marker LC3-II in macrophages, and the co-localization of LC3-II with Mtb inside infected macrophages. The intracellular mycobacterial load increased when autophagy was inhibited with wortmannin in these cells. In conclusion, our results demonstrate that neutrophils produce different EVs in response to diverse activators, and that EV-TB activate macrophages and promote the clearance of intracellular Mtb through early superoxide anion production and autophagy induction, which is a novel role for neutrophil-derived EVs in the immune response to Mtb.
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Vesículas Extracelulares/metabolismo , Macrófagos/fisiologia , Mycobacterium tuberculosis/fisiologia , Neutrófilos/imunologia , Tuberculose/imunologia , Autofagia , Diferenciação Celular , Sobrevivência Celular , Células Cultivadas , Citocinas/metabolismo , Humanos , Espaço Intracelular , Ativação de Macrófagos , Proteínas Associadas aos Microtúbulos/metabolismo , Neutrófilos/microbiologia , Transporte ProteicoRESUMO
Innate lymphoid cells (ILCs) are lymphocytes lacking antigen recognition receptors and become activated in response to cytokines and through microbe-associated molecular pattern (MAMP) receptors. ILCs are found mainly in mucosal tissues and participate in the immune response against infections and in chronic inflammatory conditions. ILCs are divided in ILC-1, ILC-2 and ILC-3, and these cells have analogue functions to those of immune adaptive response lymphocytes Th1, Th2 and Th17. ILC-1 express T-bet, produce IFNγ, protect against infections with intracellular microorganisms and are related to inflammatory bowel disease immunopathology. ILC-2 express GATA3, produce IL-4, IL-5, IL-13 and amphiregulin, protect against parasitic infections and are related to allergy and obesity immunopathology. ILC-3 express ROR(γt), produce IL-17 and IL-22, protect against fungal infections and contribute to tolerance to intestinal microbiota and intestinal repair. They are related to inflammatory bowel disease and psoriasis immunopathology. In general terms, ILCs maintain homeostasis and coadjuvate in the protection against infections.
Las células linfoides innatas (ILC) son linfocitos que carecen de receptores de reconocimiento de antígenos y se activan en respuesta a citocinas y a través de receptores de patrones moleculares asociados a microorganismos (MAMP). Las ILC se localizan preferentemente en las mucosas, y participan en la respuesta inmune contra infecciones y en enfermedades inflamatorias crónicas. Las ILC se dividen en ILC-1, ILC-2 e ILC-3, y estas células tienen funciones análogas a las de los linfocitos Th1, Th2 y Th17 de la respuesta inmune adaptativa. Las ILC-1 expresan T-bet, producen IFNγ, protegen contra infecciones con microorganismos intracelulares y están relacionados con la inmunopatología de la enfermedad inflamatoria intestinal. Las ILC-2 expresan GATA3, producen IL-4, IL-5, IL-13 y anfirregulina, protegen contra infecciones parasitarias y se relacionan con la inmunopatología de la alergia y la obesidad. Las ILC-3 expresan RORγt, producen IL-17 e IL-22, protegen contra infecciones con hongos y participan en la tolerancia a la microbiota intestinal y en la reparación intestinal. Se relacionan con la inmunopatología de la enfermedad inflamatoria intestinal y la psoriasis. En términos generales, las ILC mantienen la homeostasis y coadyuvan en la protección contra las infecciones.
Assuntos
Imunidade Inata/imunologia , Subpopulações de Linfócitos/imunologia , Doenças Cardiovasculares/imunologia , Humanos , Hipersensibilidade Imediata/imunologia , Imunidade nas Mucosas , Infecções/imunologia , Inflamação , Subpopulações de Linfócitos/classificação , Linfocinas/fisiologia , Neoplasias/imunologia , Obesidade/imunologiaRESUMO
Mast cells are crucial elements of the innate immune response. They reside in tissues that are commonly exposed to the external environment, such as the skin and mucosae, where they can rapidly detect the presence of pathogens and mount a potent inflammatory response that recruits other cellular effectors of the immune response. The contribution of mast cells to the immune response to viruses, bacteria, protozoa and multicellular parasites is well established, but there is scarce information about the role of these cells in fungal infections. In this study, we analyzed if mast cells are activated by Candida albicans and if the C-type lectin receptor Dectin-1 is involved in its recognition. We found that both yeasts and hyphae of C. albicans-induced mast cell degranulation and production of TNF-α, IL-6, IL-10, CCL3 and CCL4, while only yeasts were able to induce IL-1ß. Mast cells also produced ROS after stimulation with both dimorphic phases of C. albicans. When mast cells were activated with yeasts and hyphae, they showed decreased expression of IκBα and increased presence of phosphorylated Syk. Blockade of the receptor Dectin-1, but not Toll-like receptor 2, decreased TNF-α production by mast cell in response to C. albicans. These results indicate that mast cells are capable of sensing the two phases of C. albicans, and suggest that mast cells participate as an early inductor of inflammation during the early innate immune response to this fungus.
Assuntos
Candida albicans/imunologia , Degranulação Celular/imunologia , Inflamação/imunologia , Lectinas Tipo C/imunologia , Mastócitos/imunologia , Animais , Células Cultivadas , Quimiocina CCL3/biossíntese , Quimiocina CCL4/biossíntese , Hifas/imunologia , Quinase I-kappa B/metabolismo , Interleucina-10/biossíntese , Interleucina-1beta/biossíntese , Interleucina-6/biossíntese , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Masculino , Fosforilação/imunologia , Proteínas Tirosina Quinases/metabolismo , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo , Quinase Syk , Fator de Necrose Tumoral alfa/biossíntese , Leveduras/imunologiaRESUMO
Lungs are indispensable organs for the respiratory process, and maintaining their homeostasis is essential for human health and survival. However, during the lifetime of an individual, the lungs suffer countless insults that put at risk their delicate organization and function. Many cells of the immune system participate to maintain this equilibrium and to keep functional lungs. Among these cells, mast cells have recently attracted attention because of their ability to rapidly secrete many chemical and biological mediators that modulate different processes like inflammation, angiogenesis, cell proliferation, etc. In this review, we focus on recent advances in the understanding of the role that mast cells play in lung protection during infections, and of the relation of mast cell responses to type I hypersensitivity-associated pathologies. Furthermore, we discuss the potential role of mast cells during wound healing in the lung and its association with lung cancer, and how mast cells could be exploited as therapeutic targets in some diseases.
RESUMO
BACKGROUND: Entamoeba histolytica is a protozoan parasite that infects humans and causes amebiasis affecting developing countries. Phagocytosis of epithelial cells, erythrocytes, leucocytes, and commensal microbiota bacteria is a major pathogenic mechanism used by this parasite. A Toll/IL-1R/Resistance (TIR) domain-containing protein is required in phagocytosis in the social ameba Dictyostelium discoideum, an ameba closely related to Entamoeba histolytica in phylogeny. In insects and vertebrates, TIR domain-containing proteins regulate phagocytic and cell activation. Therefore, we investigated whether E. histolytica expresses TIR domain-containing molecules that may be involved in the phagocytosis of erythrocytes and bacteria. METHODS: Using in silico analysis we explored in Entamoeba histolytica databases for TIR domain containing sequences. After silencing TIR domain containing sequences in trophozoites by siRNA we evaluated phagocytosis of erythrocytes and bacteria. RESULTS: We identified an E. histolytica thioredoxin containing a TIR-like domain. The secondary and tertiary structure of this sequence exhibited structural similarity to TIR domain family. Thioredoxin transcripts silenced in E. histolytica trophozoites decreased erythrocytes and E. coli phagocytosis. CONCLUSION: TIR domain-containing thioredoxin of E. histolytica could be an important element in erythrocytes and bacteria phagocytosis.
Assuntos
Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Entamoeba histolytica/fisiologia , Fagocitose , Tiorredoxinas/metabolismo , Proteínas Adaptadoras de Transporte Vesicular/química , Proteínas Adaptadoras de Transporte Vesicular/genética , Biologia Computacional , Entamoeba histolytica/genética , Eritrócitos , Escherichia coli , Inativação Gênica , Conformação Proteica , Tiorredoxinas/química , Tiorredoxinas/genéticaRESUMO
The sensing of Pathogen Associated Molecular Patterns (PAMPs) by innate immune receptors, such as Toll-like receptors (TLRs), is the first step in the inflammatory response to pathogens. Entamoeba histolytica, the etiological agent of amebiasis, has a surface molecule with the characteristics of a PAMP. This molecule, which was termed lipopeptidophosphoglycan (LPPG), is recognized through TLR2 and TLR4 and leads to the release of cytokines from human monocytes, macrophages, and dendritic cells; LPPG-activated dendritic cells have increased expression of costimulatory molecules. LPPG activates NKT cells in a CD1d-dependent manner, and this interaction limits amebic liver abscess development. LPPG also induces antibody production, and anti-LPPG antibodies prevent disease development in animal models of amebiasis. Because LPPG is recognized by both the innate and the adaptive immune system (it is a "Pamptigen"), it may be a good candidate to develop a vaccine against E. histolytica infection and an effective adjuvant.