RESUMEN
Mammals have evolved sophisticated host cell death signaling pathways as an important immune mechanism to recognize and eliminate cell intruders before they establish their replicative niche. However, intracellular bacterial pathogens that have co-evolved with their host have developed a multitude of tactics to counteract this defense strategy to facilitate their survival and replication. This requires manipulation of pro-death and pro-survival host signaling pathways during infection. Obligate intracellular bacterial pathogens are organisms that absolutely require an eukaryotic host to survive and replicate, and therefore they have developed virulence factors to prevent diverse forms of host cell death and conserve their replicative niche. This review encapsulates our current understanding of these host-pathogen interactions by exploring the most relevant findings of Anaplasma spp., Chlamydia spp., Rickettsia spp. and Coxiella burnetii modulating host cell death pathways. A detailed comprehension of the molecular mechanisms through which these obligate intracellular pathogens manipulate regulated host cell death will not only increase the current understanding of these difficult-to-study pathogens but also provide insights into new tools to study regulated cell death and the development of new therapeutic approaches to control infection.
Asunto(s)
Fenómenos Fisiológicos Bacterianos , Susceptibilidad a Enfermedades , Interacciones Huésped-Patógeno , Animales , Biomarcadores , Muerte Celular/inmunología , Interacciones Huésped-Patógeno/inmunología , Humanos , Espacio Intracelular/inmunología , Espacio Intracelular/metabolismo , Espacio Intracelular/microbiología , Lisosomas/inmunología , Lisosomas/metabolismo , Lisosomas/microbiología , Viabilidad Microbiana/inmunología , Estrés Oxidativo , Fagocitosis , Especificidad de la Especie , Factores de VirulenciaRESUMEN
The Complement System (CS) plays an important role in the immune response against leptospirosis and can be activated by the Alternative and Lectin Pathways (Innate Immunity) and by the Classical Pathway (Acquired Immunity). Here we analyzed a broad range of nonpathogenic and pathogenic Leptospira strains considering their interaction with each CS pathway. We determined bacterial survival rate and CS protein deposition in the presence of purified proteins, specific component depleted sera and NHS treated with the chelating agents EDTA (inhibits all three activation pathways) or EGTA (inhibits the Classical and Lectin Pathways). We suggest that the Lectin and the Alternative Pathways have an important role to eliminate saprophytic leptospires since i) approximately 50% survival of both saprophytic strains was observed in the presence of MBL-deficient serum; ii) approximately 50% survival of Leptospira biflexa Patoc I was observed in the presence of NHS - EGTA and iii) C1q-depleted serum caused significant bacterial lysis. In all serovars investigated the deposition of C5-C9 proteins on saprophytic Leptospira strains was more pronounced when compared to pathogenic species confirming previous studies in the literature. No difference on C3 deposition was observed between nonpathogenic and pathogenic strains. In conclusion, Leptospira strains interact to different degrees with CS proteins, especially those necessary to form MAC, indicating that some strains and specific ligands could favor the binding of certain CS proteins.
Asunto(s)
Activación de Complemento , Leptospira/inmunología , Leptospirosis/inmunología , Proteínas del Sistema Complemento/inmunología , Humanos , Evasión Inmune , Leptospira/patogenicidad , Viabilidad Microbiana/inmunologíaRESUMEN
Introducción: Legionella pneumophila se sitúa entre los principales agentes causales de neumonía adquirida en la comunidad y de origen nosocomial. La inhalación de aerosoles potencialmente contaminados con la bacteria, producto de la colonización de redes y otros sistemas que utilizan agua, representa un peligro para la salud de los individuos expuestos. Objetivo: evaluar la viabilidad de L. pneumophila en muestras de agua almacenadas en diferentes intervalos de tiempo para el diagnóstico por cultivo microbiológico de Legionella spp. Métodos: Se contaminaron artificialmente muestras de agua con dos cepas de L. pneumophila de serogrupos diferentes y la conformación de una mezcla de ellas, para un total de 15 muestras. Los frascos contaminados fueron procesados a las 24 h, 72 h, 7 días, 14 días y 21 días. Se realizó cultivo microbiológico según ISO 11731: 2004 y PNO 03-013: 2015. Resultados: Se demostró viabilidad de la bacteria en muestras almacenadas hasta 21 días. El método de concentración por filtración resultó tener los mayores recobrados del microorganismo. Conclusiones: El tiempo de almacenamiento de las muestras afecta la viabilidad de L. pneumophila. Sienta las bases para estudios posteriores de robustez del diagnóstico de L. pneumophila como parte del servicio que presta el Centro de Investigaciones Científicas de la Defensa Civil en los programas de prevención y control Legionella spp. en instalaciones de interés turístico e industrial(AU)
Introduction: Legionella pneumophila is one of the main causative agents of community- and hospital-acquired pneumonia. Inhalation of sprays potentially contaminated with the bacterium, due to the colonization of networks and other systems using water, is a hazard to the health of exposed individuals. Objective: Evaluate the viability of L. pneumophila in samples of water stored at various time intervals for the microbiological culture diagnosis of Legionella spp. Methods: Water samples were artificially contaminated with two strains of L. pneumophila from different serogroups and a mixture of them, for a total of 15 samples. The contaminated vessels were processed at 24 h, 72 h, 7 d, 14 d and 21 d. Microbiological culture was performed in compliance with ISO 11731: 2004 and PNO 03-013: 2015. Results: The bacterium was found to be viable in samples stored up to 21 days. The filtration concentration method obtained the greatest amount of the microorganism. Conclusions: Storage time of the samples affects the viability of L. pneumophila. The study lays the foundations for further research about the validity of L. pneumophila diagnosis as part of the service offered by the Civil Defense Scientific Research Center in Legionella spp. prevention and control programs for tourist and industrial facilities(AU)
Asunto(s)
Humanos , Enfermedad de los Legionarios/inmunología , Muestras de Agua , Viabilidad Microbiana/inmunología , Neumonía/microbiología , ComunicaciónRESUMEN
Several pathogens including Gram-negative bacteria hijack complement regulators to escape host's innate response. Pathogenic Leptospira species bind Factor H, C4b binding protein and vitronectin from the complement system. We evaluated the ability of low passage (LP) and culture-attenuated (CA) pathogenic strains of Leptospira, to bind Factor H. We used LOCaS46 (Leptospira interrogans sv Canicola), LOVe30 (L. interrogans sv Icterohaemorrhagiae) and MOCA45 (L. santarosai sv Tarassovi), and ten high passage strains of Leptospira [used in the microscopic agglutination test (MAT)]. Afterwards, we assessed their survival in normal human serum (NHS). Interestingly, the ability in binding Factor H was higher for LOCaS46 and LOVe30 LP strains, than for the respective CA strains suggesting that the ability of evading the alternative complement pathway is lost after culture attenuation. Accordingly, the level of mRNA expression of the Factor H binding proteins, LigA, LigB and Lsa23 was higher in these LP strains than in the corresponding CA strains. Unexpectedly, no difference in Factor H binding and surviving was observed between LP and CA MOCA45 strains. The high passage MAT-reference strains showed variation in Factor H binding ability, but, in most cases, the ability for capturing Factor H by Leptospira strains correlated with their survival in NHS.
Asunto(s)
Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Portadoras/metabolismo , Regulación Bacteriana de la Expresión Génica , Leptospira/inmunología , Leptospira/patogenicidad , Proteínas Portadoras/genética , Factor H de Complemento/metabolismo , Humanos , Evasión Inmune/genética , Leptospira/genética , Leptospirosis/microbiología , Viabilidad Microbiana/genética , Viabilidad Microbiana/inmunología , Unión Proteica , ARN Mensajero/genéticaRESUMEN
It is well established that B cells play an important role during infections beyond antibody production. B cells produce cytokines and are APCs for T cells. Recently, it has become clear that several pathogenic bacterial genera, such as Salmonella, Brucella, Mycobacterium, Listeria, Francisella, Moraxella, and Helicobacter, have evolved mechanisms such as micropinocytosis induction, inflammasome down-regulation, inhibitory molecule expression, apoptosis induction, and anti-inflammatory cytokine secretion to manipulate B cell functions influencing immune responses. In this review, we summarize our current understanding of B cells as targets of bacterial infection and the mechanisms by which B cells become a niche for bacterial survival and replication away from extracellular immune responses such as complement and antibodies.
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Linfocitos B/inmunología , Infecciones Bacterianas/microbiología , Bacterias Gramnegativas/inmunología , Bacterias Grampositivas/inmunología , Evasión Inmune , Animales , Anticuerpos Antibacterianos/biosíntesis , Apoptosis/inmunología , Linfocitos B/microbiología , Infecciones Bacterianas/inmunología , Infecciones Bacterianas/patología , Citocinas/biosíntesis , Citocinas/inmunología , Bacterias Gramnegativas/crecimiento & desarrollo , Bacterias Gramnegativas/patogenicidad , Bacterias Grampositivas/crecimiento & desarrollo , Bacterias Grampositivas/patogenicidad , Humanos , Inflamasomas/inmunología , Viabilidad Microbiana/inmunología , Pinocitosis/inmunologíaRESUMEN
Bordetella pertussis, the etiological agent of whooping cough, still causes outbreaks. We recently found evidence that B. pertussis can survive and even replicate inside human macrophages, indicating that this host cell might serve as a niche for persistence. In this work, we examined the interaction of B. pertussis with a human monocyte cell line (THP-1) that differentiates into macrophages in culture in order to investigate the host cell response to the infection and the mechanisms that promote that intracellular survival. To that end, we investigated the expression profile of a selected number of genes involved in cellular bactericidal activity and the inflammatory response during the early and late phases of infection. The bactericidal and inflammatory response of infected macrophages was progressively downregulated, while the number of THP-1 cells heavily loaded with live bacteria increased over time postinfection. Two of the main toxins of B. pertussis, pertussis toxin (Ptx) and adenylate cyclase (CyaA), were found to be involved in manipulating the host cell response. Therefore, failure to express either toxin proved detrimental to the development of intracellular infections by those bacteria. Taken together, these results support the relevance of host defense gene manipulation to the outcome of the interaction between B. pertussis and macrophages.
Asunto(s)
Bordetella pertussis/inmunología , Regulación de la Expresión Génica , Interacciones Huésped-Patógeno/genética , Interacciones Huésped-Patógeno/inmunología , Macrófagos/inmunología , Macrófagos/metabolismo , Tos Ferina/genética , Tos Ferina/inmunología , Bordetella pertussis/genética , Línea Celular , Citocinas/genética , Citocinas/metabolismo , Humanos , Mediadores de Inflamación/metabolismo , Proteína 2 de la Membrana Asociada a los Lisosomas/genética , Proteína 2 de la Membrana Asociada a los Lisosomas/metabolismo , Macrófagos/microbiología , Viabilidad Microbiana/inmunología , Monocitos/inmunología , Monocitos/metabolismo , Monocitos/microbiología , Fagocitosis , Factores de Virulencia/genética , Tos Ferina/microbiologíaRESUMEN
Tuberculosis has great public health impact with high rates of mortality and the only prophylactic measure for it is the Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine. The present study evaluated the release of cytokines [interleukin (IL)-1, tumour necrosis factor and IL-6] and chemokines [macrophage inflammatory protein (MIP)-1α and MIP-1ß] by THP-1 derived macrophages infected with BCG vaccine obtained by growing mycobacteria in Viscondessa de Moraes Institute medium medium (oral) or Sauton medium (intradermic) to compare the effects of live and heat-killed (HK) mycobacteria. Because BCG has been reported to lose viability during the lyophilisation process and during storage, we examined whether exposing BCG to different temperatures also triggers differences in the expression of some important cytokines and chemokines of the immune response. Interestingly, we observed that HK mycobacteria stimulated cytokine and chemokine production in a different pattern from that observed with live mycobacteria.
Asunto(s)
Quimiocinas/metabolismo , Macrófagos/inmunología , Viabilidad Microbiana/inmunología , Mycobacterium bovis/clasificación , Línea Celular , Quimiocina CCL3/metabolismo , Quimiocina CCL4/metabolismo , Citocinas/metabolismo , Humanos , Interleucina-1/metabolismo , Interleucina-6/metabolismo , Macrófagos/clasificación , Macrófagos/efectos de los fármacos , Mycobacterium bovis/inmunología , Factor de Necrosis Tumoral alfa/metabolismo , Vacunas de Productos InactivadosRESUMEN
Tuberculosis has great public health impact with high rates of mortality and the only prophylactic measure for it is the Mycobacterium bovisbacillus Calmette-Guérin (BCG) vaccine. The present study evaluated the release of cytokines [interleukin (IL)-1, tumour necrosis factor and IL-6] and chemokines [macrophage inflammatory protein (MIP)-1α and MIP-1β] by THP-1 derived macrophages infected with BCG vaccine obtained by growing mycobacteria in Viscondessa de Moraes Institute medium medium (oral) or Sauton medium (intradermic) to compare the effects of live and heat-killed (HK) mycobacteria. Because BCG has been reported to lose viability during the lyophilisation process and during storage, we examined whether exposing BCG to different temperatures also triggers differences in the expression of some important cytokines and chemokines of the immune response. Interestingly, we observed that HK mycobacteria stimulated cytokine and chemokine production in a different pattern from that observed with live mycobacteria.
Asunto(s)
Humanos , Quimiocinas , Macrófagos/inmunología , Viabilidad Microbiana/inmunología , Mycobacterium bovis/clasificación , Línea Celular , Citocinas , Interleucina-1 , Macrófagos/clasificación , Macrófagos/efectos de los fármacos , Mycobacterium bovis/inmunología , Factor de Necrosis Tumoral alfa , Vacunas de Productos InactivadosRESUMEN
OBJECTIVE: To compare the immunogenicity of 1 vs 2 doses of meningococcal polysaccharide conjugate vaccine (MCV4) in youth infected with human immunodeficiency virus (HIV). STUDY DESIGN: P1065 was a phase I/II immunogenicity and safety trial of MCV4 in 324 youth infected with HIV performed at 27 sites of the International Maternal Pediatric Adolescent AIDS Clinical Trials Group network in the US. At entry subjects received 1 dose of MCV4. At 24 weeks, those with screening cluster of differentiation 4 (CD4)% ≥ 15 were randomized to receive a second dose or not, and all with screening CD4% <15 received a second dose. Immunogenicity was evaluated as the proportion of subjects with a ≥ 4-fold rise from entry in serum bactericidal antibody against each meningococcal serogroup (SG) at weeks 28 and 72. Logistic regression models adjusting for HIV disease severity were used to evaluate the effect of 1 vs 2 MCV4 doses among those with screening CD4% ≥ 15. RESULTS: Subjects randomized to receive 2 vs 1 MCV4 dose had significantly higher response rates to all SGs at week 28 and to all except Neisseria meningitidis SG Y at week 72, with adjusted ORs of 2.5-5.6. In 31 subjects with screening CD4% <15 who received 2 MCV4 doses, response rates ranged from 22%-55% at week 28 and 6%-28% at week 72. CONCLUSION: In youth infected with HIV with a CD4% ≥ 15, a second dose of MCV4 given 6 months after the initial dose significantly improves response rates at 28 and 72 weeks. Subjects with CD4% <15 at entry had lower response rates despite 2 doses of MCV4.
Asunto(s)
Infecciones por VIH/inmunología , Vacunas Meningococicas/administración & dosificación , Adolescente , Adulto , Anticuerpos Antibacterianos/análisis , Niño , Femenino , Humanos , Masculino , Infecciones Meningocócicas/prevención & control , Vacunas Meningococicas/inmunología , Viabilidad Microbiana/inmunología , Neisseria meningitidis/clasificación , Vacunas Conjugadas/administración & dosificación , Vacunas Conjugadas/inmunología , Adulto JovenRESUMEN
Clostridium perfringens is the causative agent of a variety of histotoxic infections in humans and animals. Studies on the early events of C. perfringens infections have been largely focused on the interactions between their vegetative cells and macrophages. Consequently, in the current study we have examined the interactions between C. perfringens spores and Raw 264.7 macrophages. Raw 264.7 cells were able to interact and phagocytose Clostridium perfringens spores of a food poisoning isolate, strain SM101, and a non-food borne isolate, strain F4969, albeit to different extents. Phagocytosis and to a lesser extent, association, of C. perfringens spores by Raw 2647 macrophages was completely inhibited in presence of cytochalasin D. Complement increased association and phagocytosis of C. perfringens spores by Raw 264.7 macrophages. Survival of C. perfringens spores during macrophage infection seems to depend on the ability of spore germination during infection as: (i) F4969 spores germinated during infection with Raw 264.7 macrophages and subsequently killed by macrophages; and (ii) SM101 spores remained dormant inside Raw 264.7 macrophages and thus survived up to 24 h of infection. The in vitro spore-resistance factors, α/ß-type SASP, SpmA/B proteins and spore's core water content, seems to play no role in mediating SM101 spore-resistance to macrophages. Collectively, these results might well have implications in understanding the initial stages of infections by C. perfringens spores.
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Clostridium perfringens/fisiología , Macrófagos/metabolismo , Macrófagos/microbiología , Actinas/metabolismo , Animales , Línea Celular , Clostridium perfringens/química , Clostridium perfringens/inmunología , Proteínas del Sistema Complemento/metabolismo , Interacciones Huésped-Patógeno , Macrófagos/inmunología , Ratones , Viabilidad Microbiana/inmunología , Fagocitosis , Multimerización de Proteína , Esporas Bacterianas , Agua/químicaRESUMEN
The aim of this work was to evaluate the microencapsulation by spray-drying of inactivated Vibrio cholerae, using methacrylic copolymers Eudragit® L30D-55 and FS30D. The microparticles obtained presented a particle size around 3.0 µm. The preparation temperature affected the morphology and the antigenicity of microparticles, but it did not affect the V. cholerae content. In vitro release studies showed that in acid medium less than 5% of bacteria was released, and in neutral medium, Eudragit® L30D-55 microparticles released 86% after 24 h, whereas FS30D released less than 30%. Rats inoculated with microparticles exhibited vibriocidal antibody titres. Microencapsulation by spray-drying of inactivated V. cholerae could be proposed as a method to obtain an oral vaccine which provides controlled release of the bacteria.
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Vacunas contra el Cólera/administración & dosificación , Vacunas contra el Cólera/inmunología , Cólera/inmunología , Vibrio cholerae/inmunología , Administración Oral , Animales , Cólera/prevención & control , Desecación , Composición de Medicamentos , Viabilidad Microbiana/inmunología , Microesferas , Ácidos Polimetacrílicos , Ratas , Vacunas de Productos Inactivados/inmunologíaAsunto(s)
Proteínas Bacterianas/farmacología , Toxinas Bacterianas/farmacología , Endotoxinas/farmacología , Proteínas Hemolisinas/farmacología , Leucocitos Mononucleares/efectos de los fármacos , Viabilidad Microbiana/inmunología , Amicacina/farmacología , Antibacterianos/farmacología , Toxinas de Bacillus thuringiensis , Células Cultivadas/efectos de los fármacos , Células Cultivadas/inmunología , Concanavalina A/farmacología , Evaluación Preclínica de Medicamentos , Humanos , Leucocitos Mononucleares/inmunología , Viabilidad Microbiana/efectos de los fármacos , Proteus mirabilis/efectos de los fármacos , Proteus mirabilis/crecimiento & desarrollo , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/crecimiento & desarrollo , Proteínas Recombinantes/farmacología , Salmonella/efectos de los fármacos , Salmonella/crecimiento & desarrollo , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/crecimiento & desarrolloAsunto(s)
Humanos , Proteínas Bacterianas/farmacología , Toxinas Bacterianas/farmacología , Endotoxinas/farmacología , Proteínas Hemolisinas/farmacología , Leucocitos Mononucleares/efectos de los fármacos , Viabilidad Microbiana/inmunología , Amicacina/farmacología , Antibacterianos/farmacología , Células Cultivadas/efectos de los fármacos , Células Cultivadas/inmunología , Concanavalina A/farmacología , Evaluación Preclínica de Medicamentos , Leucocitos Mononucleares/inmunología , Viabilidad Microbiana/efectos de los fármacos , Proteus mirabilis/efectos de los fármacos , Proteus mirabilis/crecimiento & desarrollo , Pseudomonas aeruginosa/efectos de los fármacos , Pseudomonas aeruginosa/crecimiento & desarrollo , Proteínas Recombinantes/farmacología , Salmonella/efectos de los fármacos , Salmonella/crecimiento & desarrollo , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/crecimiento & desarrolloRESUMEN
Mycobacterium sp é um microrganismo intracelular facultativo que vive em macrófagos no interior de fagossomas que restringem a fusão com lisossomas da célula hospedeira. Recentemente foi demonstrado que micobactéria patogênica reside em vacúolos não acidificados. Células J774 pré-ativadas ou não com IFN-y foram infectadas com M intracellulare avirulenta ou virulenta na proporção de lO bacilos por célula. A virulência dos bacilos foi determinada pelas características morfológicas das colônias. Neste trabalho nós avaliamos, comparativamente, a produção de NO pelas células e a viabilidade intracelular dos bacilos. Micobactérias avirulentas induziram maior produção de NO, em comparação com as virulentas. A viabilidade intracelular dos bacilos avirulentos diminuiu pelo tratamento das células com IFN-y e foi revertida pela adição de AMG, um inibidor da iNOS. A viabilidade da variante virulenta não foi alterada pelo tratamento com IFN-y ou IFN-y e AMG. Estudos em microscopia eletrônica foram realizados para avaliar a capacidade de fagossomas fusionarem com lisossomas marcados com partículas de Au-BSA. Vinte e quatro horas após a infecção, 77% de fagossomas contendo micobactéria avirulenta fusionaram com lisossomas, em contraste com 50% de fagossomas contendo micobactéria virulenta. A fusão de fagossomas com lisossomas aumentou com o tratamento por IFN-y, enquanto que a adição de AMG provocou a redução da fusão de fagossomas formados por micobactéria avirulenta ou virulenta com lisossomas. Demonstramos que a produção de NO é dependente da virulência das micobactérias e que o NO favorece a fusão de fagossomas com lisossomas e diminui a viabilidade dos bacilos.