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Salmonella enterica serovar Typhi (S. Typhi) porins, OmpC and OmpF, are potent inducers of the immune response against S. Typhi in mice and humans. Vaccination with porins induces the protection against 500 LD50 of S. Typhi, life-lasting bactericidal antibodies and effector T cell responses in mice; however, the nature of the memory T cell compartment and its contribution to protection remains unknown. In this work, we firstly observed that vaccination with porins induces in situ (skin) CD4+ and CD8+ T cell responses. Analysis of the porin-specific functional responses of skin CD4+ and CD8+ T cells showed IFN-gamma- and IL-17-producing cells in both T cell populations. The memory phenotype of porin-specific T cells indicated the presence of resident and effector memory phenotypes in the skin, and a central memory phenotype in the skin-draining lymph node. In addition, we demonstrated that vaccination with porins via skin reduces the bacterial burden following challenge. Finally, evaluating the role of the circulating T cell memory population in protection, we showed that circulating memory CD4+ and CD8+ T cells are crucial in porin-mediated protection against S. Typhi. Overall, this study highlights the importance of inducing circulating memory T cell responses in order to achieve the optimal protection provided by porins, showing a mechanism that could be sought in the rational development of vaccines.
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Introduction. The Salmonella Typhimurium monophasic variant (1,4,[5],12:i:-) is currently the most commonly detected variant in Salmonella surveillance programs worldwide. In Colombia, the Salmonella enterica monophasic variant is the fourth most common clinical isolate recovered through the laboratory surveillance of the Grupo de Microbiología from the Instituto Nacional de Salud; however, it is unknown whether these isolates are closely related to the monophasic Typhimurium variant, which circulates globally, and their genetic and phenotypic characteristics have not been reported. Objective. To characterize monophasic Salmonella enterica isolates identified in Colombia from 2015 to 2018 by the Instituto Nacional de Salud. Materials and methods. Two hundred eighty-six clinical isolates of the monophasic Salmonella enterica variant were analyzed by PCR or whole-genome sequencing to confirm whether they corresponded to the Salmonella Typhimurium monophasic variant while the genetic structure of the operon encoding the second flagellar phase was determined in 54 isolates. Motility, growth, and expression of the outer membrane proteins were evaluated in 23 isolates. Results. During the study period in Colombia, 61% (n=174) of Salmonella monophasic isolates belonged to Salmonella Typhimurium serovar monophasic (1,4,[5],12:i-). Of these, 64.8% (n=35/54) were related to the European/Spanish clone and 13% (n=7/54) to the U.S. clone. Two isolates recovered from urine samples showed differences in motility, growth, and the absence of the OmpD porin in M9 minimal medium. Conclusions. Most of the monophasic Salmonella Typhimurium variants that have circulated in Colombia since 2015 lacked the second phase of operon fljAB, which is related to the European/Spanish clone. The results evidenced phenotypic changes in urine samples suggesting bacterial adaptation in the case of these invasive samples.
Introducción. La variante monofásica (1,4,[5],12:i:-) de Salmonella Typhimurium ocupa los primeros lugares en los programas de vigilancia de Salmonella a nivel mundial. En Colombia, Salmonella enterica variante monofásica alcanza el cuarto lugar en cuanto a los aislamientos clínicos recuperados por medio de la vigilancia por laboratorio del Grupo de Microbiología del Instituto Nacional de Salud, pero se desconoce si dichos aislamientos están relacionados con la variante monofásica de Typhimurium que circula a nivel global, y con sus características genéticas y fenotípicas. Objetivo. Caracterizar los aislamientos de Salmonella monofásica recuperados en Colombia entre el 2015 y el 2018 por el Grupo de Microbiología del Instituto Nacional de Salud. Materiales y métodos. Se analizaron 286 aislamientos clínicos de Salmonella enterica variante monofásica mediante PCR o secuenciación del genoma completo (Whole Genome Sequencing, WGS) para confirmar si correspondían a Salmonella Typhimurium variante monofásica, en tanto que, en 54 aislamientos, se determinó la estructura genética del operón que codifica la segunda fase flagelar y, en 23, se evaluó la motilidad, el crecimiento y la expresión de las proteínas de membrana externa. Resultados. El 61 % (n=174) de los aislamientos de Salmonella monofásica correspondió a Salmonella Typhimurium serovar monofásico. El 64,8 % (n=35/54) se relacionó con el clon europeo-español y, el 13 % (n=7/54), con el estadounidense. En dos aislamientos de orina se encontró una diferencia significativa en la motilidad y el crecimiento, así como ausencia de la porina OmpD en medio mínimo M9. Conclusiones. En el periodo de estudio, circuló en Colombia la variante monofásica de Salmonella Typhimurium relacionada con el clon europeo-español, y se registró ausencia total del operón fljAB. Los resultados evidenciaron cambios fenotípicos en los aislamientos provenientes de muestras de orina que sugieren adaptación en procesos invasivos.
Assuntos
Salmonella typhimurium/genética , Sorogrupo , Fenômenos Fisiológicos Bacterianos , Proteínas de Bactérias/genética , Colômbia , Europa (Continente) , Flagelos/genética , Flagelina/genética , Variação Genética , Humanos , Proteínas Repressoras/genética , Salmonella enterica/classificação , Salmonella enterica/genética , Salmonella typhimurium/isolamento & purificação , Salmonella typhimurium/fisiologia , EspanhaRESUMO
Resumen: Introducción. La variante monofásica (1,4,[5],12:i:-) de Salmonella Typhimurium ocupa los primeros lugares en los programas de vigilancia de Salmonella a nivel mundial. En Colombia, Salmonella enterica variante monofásica alcanza el cuarto lugar en cuanto a los aislamientos clínicos recuperados por medio de la vigilancia por laboratorio del Grupo de Microbiología del Instituto Nacional de Salud, pero se desconoce si dichos aislamientos están relacionados con la variante monofásica de Typhimurium que circula a nivel global, y con sus características genéticas y fenotípicas. Objetivo. Caracterizar los aislamientos de Salmonella monofásica recuperados en Colombia entre el 2015 y el 2018 por el Grupo de Microbiología del Instituto Nacional de Salud. Materiales y métodos. Se analizaron 286 aislamientos clínicos de Salmonella enterica variante monofásica mediante PCR o secuenciación del genoma completo (Whole Genome Sequencing, WGS) para confirmar si correspondían a Salmonella Typhimurium variante monofásica, en tanto que, en 54 aislamientos, se determinó la estructura genética del operón que codifica la segunda fase flagelar y, en 23, se evaluó la motilidad, el crecimiento y la expresión de las proteínas de membrana externa. Resultados. El 61 % (n=174) de los aislamientos de Salmonella monofásica correspondió a Salmonella Typhimurium serovar monofásico. El 64,8 % (n=35/54) se relacionó con el clon europeo-español y, el 13 % (n=7/54), con el estadounidense. En dos aislamientos de orina se encontró una diferencia significativa en la motilidad y el crecimiento, así como ausencia de la porina OmpD en medio mínimo M9. Conclusiones. En el periodo de estudio, circuló en Colombia la variante monofásica de Salmonella Typhimurium relacionada con el clon europeo-español, y se registró ausencia total del operón fljAB. Los resultados evidenciaron cambios fenotípicos en los aislamientos provenientes de muestras de orina que sugieren adaptación en procesos invasivos.
Abstract: Introduction. The Salmonella Typhimurium monophasic variant (1,4,[5],12:i:-) is currently the most commonly detected variant in Salmonella surveillance programs worldwide. In Colombia, the Salmonella enterica monophasic variant is the fourth most common clinical isolate recovered through the laboratory surveillance of the Grupo de Microbiología from the Instituto Nacional de Salud; however, it is unknown whether these isolates are closely related to the monophasic Typhimurium variant, which circulates globally, and their genetic and phenotypic characteristics have not been reported. Objective. To characterize monophasic Salmonella enterica isolates identified in Colombia from 2015 to 2018 by the Instituto Nacional de Salud. Materials and methods. Two hundred eighty-six clinical isolates of the monophasic Salmonella enterica variant were analyzed by PCR or whole-genome sequencing to confirm whether they corresponded to the Salmonella Typhimurium monophasic variant while the genetic structure of the operon encoding the second flagellar phase was determined in 54 isolates. Motility, growth, and expression of the outer membrane proteins were evaluated in 23 isolates. Results. During the study period in Colombia, 61% (n=174) of Salmonella monophasic isolates belonged to Salmonella Typhimurium serovar monophasic (1,4,[5],12:i-). Of these, 64.8% (n=35/54) were related to the European/Spanish clone and 13% (n=7/54) to the U.S. clone. Two isolates recovered from urine samples showed differences in motility, growth, and the absence of the OmpD porin in M9 minimal medium. Conclusions. Most of the monophasic Salmonella Typhimurium variants that have circulated in Colombia since 2015 lacked the second phase of operon fljAB, which is related to the European/Spanish clone. The results evidenced phenotypic changes in urine samples suggesting bacterial adaptation in the case of these invasive samples.
Assuntos
Salmonella typhimurium , Porinas , Colômbia , Vigilância em Desastres , FlagelosRESUMO
In the last decade, the development of novel programmable cell lytic systems based on different inducible genetic constructs like the holin-endolysin and lysozyme appears as a promising alternative to circumvent the use of costly enzymes and mechanical disrupters for downstream processing of intracellular microbial products. Despite the advances, upon activation of these systems the cellular disruption of the biocatalyst occurs in an extended period, thus delaying the recovery of poly(3-hydroxyalkanoate) (PHA). Herein the osmotic state of Pseudomonas putida KT2440 was engineered by inactivating the inner-membrane residing rescue valve MscL, which is responsible mainly for circumventing low-osmolarity challenges. Then the major outer membrane porin OprF and the specific porin OprE were overproduced during PHA producing conditions on decanoate-grown cells. The engineered P. putida strains carrying each porin showed no impairment on growth rate and final biomass and PHA yield after 48 h cultivation. Expression of both porins in tandem in the mutant strain KTΔmscL-oprFE led to a slight reduction of the biomass synthesis (â¼10%) but higher PHA accumulation (%wt) relative to the cell dry mass. Each strain was then challenged to an osmotic upshift for 1 h and subsequently to a rapid passage to a hypotonic condition where the membrane stability of the KTΔmscL-oprFE suffered damage, resulting in a rapid reduction of cell viability. Cell disruption accounted for >95% of the cell population within 3 h as reported by colony forming units (CFU), FACS analyses, and transmission electron microscopy. PHA recovery yielded 94.2% of the biosynthesized biopolymer displaying no significant alterations on the final monomer composition. This study can serve as an efficient genetic platform for the recovery of any microbial intracellular compound allowing less unit operation steps for cellular disruption.
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Carbapenems are considered last-line agents for the treatment of serious infections caused by Klebsiella pneumoniae, and this microorganism may exhibit resistance to -lactam antibiotics due to different mechanisms of resistance. We evaluated 27 isolates of K. pneumoniae resistant to carbapenems recovered from inpatients at the University Hospital of Santa Maria-RS from July 2013 to August 2014. We carried out antimicrobial susceptibility, carbapenemase detection, testing for the presence of efflux pump by broth microdilution and loss of porin by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Genetic similarity was evaluated by ERIC-PCR. High levels of resistance were verified by the minimum inhibitory concentration for the antimicrobials tested. The blaKPC gene was present in 89% of the clinical isolates. Blue-Carba and combined disk with AFB tests showed 100% concordance, while the combined disk test with EDTA showed a high number of false-positives (48%) compared with the gold-standard genotypic test. Four isolates showed a phenotypic resistance profile consistent with the overexpression of the efflux pump, and all clinical isolates had lost one or both porins. The ERIC-PCR dendrogram demonstrated the presence of nine clusters. The main mechanism of resistance to carbapenems found in the assessed isolates was the presence of the blaKPC gene.(AU)
Assuntos
Humanos , Klebsiella pneumoniae , Carbapenêmicos , Porinas , Resistência beta-Lactâmica , Resistência Microbiana a MedicamentosRESUMO
Abstract Carbapenems are considered last-line agents for the treatment of serious infections caused by Klebsiella pneumoniae, and this microorganism may exhibit resistance to β-lactam antibiotics due to different mechanisms of resistance. We evaluated 27 isolates of K. pneumoniae resistant to carbapenems recovered from inpatients at the University Hospital of Santa Maria-RS from July 2013 to August 2014. We carried out antimicrobial susceptibility, carbapenemase detection, testing for the presence of efflux pump by broth microdilution and loss of porin by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Genetic similarity was evaluated by ERIC-PCR. High levels of resistance were verified by the minimum inhibitory concentration for the antimicrobials tested. The blaKPC gene was present in 89% of the clinical isolates. Blue-Carba and combined disk with AFB tests showed 100% concordance, while the combined disk test with EDTA showed a high number of false-positives (48%) compared with the gold-standard genotypic test. Four isolates showed a phenotypic resistance profile consistent with the overexpression of the efflux pump, and all clinical isolates had lost one or both porins. The ERIC-PCR dendrogram demonstrated the presence of nine clusters. The main mechanism of resistance to carbapenems found in the assessed isolates was the presence of the blaKPC gene.
Assuntos
Humanos , Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Farmacorresistência Bacteriana , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Klebsiella pneumoniae/metabolismo , Testes de Sensibilidade MicrobianaRESUMO
Several microbial components, such as bacterial DNA and flagellin, have been used as experimental vaccine adjuvants because of their inherent capacity to efficiently activate innate immune responses. Likewise, our previous work has shown that the major Salmonella Typhi (S. Typhi) outer membrane proteins OmpC and OmpF (porins) are highly immunogenic protective antigens that efficiently stimulate innate and adaptive immune responses in the absence of exogenous adjuvants. Moreover, S. Typhi porins induce the expression of costimulatory molecules on antigen-presenting cells through toll-like receptor canonical signaling pathways. However, the potential of major S. Typhi porins to be used as vaccine adjuvants remains unknown. Here, we evaluated the adjuvant properties of S. Typhi porins against a range of experimental and clinically relevant antigens. Co-immunization of S. Typhi porins with ovalbumin (OVA), an otherwise poorly immunogenic antigen, enhanced anti-OVA IgG titers, antibody class switching, and affinity maturation. This adjuvant effect was dependent on CD4+ T-cell cooperation and was associated with an increase in IFN-γ, IL-17A, and IL-2 production by OVA-specific CD4+ T cells. Furthermore, co-immunization of S. Typhi porins with an inactivated H1N1 2009 pandemic influenza virus experimental vaccine elicited higher hemagglutinating anti-influenza IgG titers, antibody class switching, and affinity maturation. Unexpectedly, co-administration of S. Typhi porins with purified, unconjugated Vi capsular polysaccharide vaccine (Vi CPS)-a T-independent antigen-induced higher IgG antibody titers and class switching. Together, our results suggest that S. Typhi porins OmpC and OmpF are versatile vaccine adjuvants, which could be used to enhance T-cell immune responses toward a Th1/Th17 profile, while improving antibody responses to otherwise poorly immunogenic T-dependent and T-independent antigens.
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Carbapenems are considered last-line agents for the treatment of serious infections caused by Klebsiella pneumoniae, and this microorganism may exhibit resistance to ß-lactam antibiotics due to different mechanisms of resistance. We evaluated 27 isolates of K. pneumoniae resistant to carbapenems recovered from inpatients at the University Hospital of Santa Maria-RS from July 2013 to August 2014. We carried out antimicrobial susceptibility, carbapenemase detection, testing for the presence of efflux pump by broth microdilution and loss of porin by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Genetic similarity was evaluated by ERIC-PCR. High levels of resistance were verified by the minimum inhibitory concentration for the antimicrobials tested. The blaKPC gene was present in 89% of the clinical isolates. Blue-Carba and combined disk with AFB tests showed 100% concordance, while the combined disk test with EDTA showed a high number of false-positives (48%) compared with the gold-standard genotypic test. Four isolates showed a phenotypic resistance profile consistent with the overexpression of the efflux pump, and all clinical isolates had lost one or both porins. The ERIC-PCR dendrogram demonstrated the presence of nine clusters. The main mechanism of resistance to carbapenems found in the assessed isolates was the presence of the blaKPC gene.
Assuntos
Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Farmacorresistência Bacteriana , Humanos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Klebsiella pneumoniae/metabolismo , Testes de Sensibilidade MicrobianaRESUMO
A total of 31 unrelated OXA-23-producing Acinetobacter baumannii strains isolated from 14 hospitals located in distinct Brazilian regions were evaluated in this study. These isolates were grouped into 12 different sequence types (STs), of which 7 had unique allelic sequences (ST188, ST189, ST190, ST191, ST192, ST228, and ST299). Most isolates belonged to the clonal complex CC79 followed by CC15 and CC1. Only polymyxin B and minocycline showed good activity against the OXA-23-producing A. baumannii clones. The ISAba1 upstream blaOXA-23, blaOXA-51-like, or ampC was found in 100%, 54.8%, and 77.4% of the isolates, respectively. High resistance rates to ceftazidime and cefotaxime were observed among those isolates possessing ISAba1 upstream ampC, in contrast to those isolates that did not carry this configuration. Moreover, a ≥2 Log2 decrease in the MICs of meropenem and ceftazidime was observed in the presence of phenyl-arginine-ß-naphthylamide for 80.6% and 54.8% of isolates, respectively. Overexpression of the adeB was observed in 61.3% of isolates, particularly among those isolates belonging to the ST1 (CC1). It was also verified that ompW was down-regulated in all isolates belonging to the ST15 (CC15). On the other hand, carO and omp33-36 genes were overexpressed in 48.4% and 58.1% of the isolates, respectively. In this study, we show that overexpression of AdeABC system could significantly contribute for resistance to meropenem and ceftazidime among OXA-23-producing A. baumannii clones in Brazil, demonstrating the complexity involved in the ß-lactam resistance in such isolates.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/genética , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , Acinetobacter baumannii/classificação , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Brasil , Carbapenêmicos/farmacologia , Eletroforese em Gel de Campo Pulsado , Expressão Gênica , Humanos , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Filogenia , Filogeografia , Reação em Cadeia da Polimerase em Tempo RealRESUMO
An investigation was carried out into the genetic mechanisms responsible for multidrug resistance in nine carbapenem-resistant Pseudomonas aeruginosaisolates from different hospitals in Recife, Brazil. Susceptibility to antimicrobial agents was determined by broth microdilution. Polymerase chain reaction (PCR) was employed to detect the presence of genes encoding β-lactamases, aminoglycoside-modifying enzymes (AMEs), 16S rRNA methylases, integron-related genes and OprD. Expression of genes coding for efflux pumps and AmpC cephalosporinase were assessed by quantitative PCR. The outer membrane proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The blaSPM-1, blaKPC-2 and blaGES-1 genes were detected in P. aeruginosaisolates in addition to different AME genes. The loss of OprD in nine isolates was mainly due to frameshift mutations, premature stop codons and point mutations. An association of loss of OprD with the overexpression of MexAB-OprM and MexXY-OprM was observed in most isolates. Hyper-production of AmpC was also observed in three isolates. Clonal relationship of the isolates was determined by repetitive element palindromic-PCR and multilocus sequence typing. Our results show that the loss of OprD along with overexpression of efflux pumps and β-lactamase production were responsible for the multidrug resistance in the isolates analysed.
Assuntos
Humanos , Carbapenêmicos/metabolismo , Farmacorresistência Bacteriana Múltipla/genética , Mutação , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/genética , Resistência beta-Lactâmica/genética , beta-Lactamases/metabolismo , Aminoglicosídeos/metabolismo , Anfotericina B/análogos & derivados , Anfotericina B/metabolismo , Antifúngicos/metabolismo , Brasil , Cefalosporinase/classificação , Cefalosporinase/metabolismo , Códon sem Sentido/metabolismo , Ativação Enzimática/genética , Mutação da Fase de Leitura/genética , Regulação Bacteriana da Expressão Gênica/genética , Proteínas de Membrana Transportadoras/metabolismo , Metiltransferases/metabolismo , Nucleotidiltransferases/metabolismo , Mutação Puntual/genética , Porinas/metabolismo , Pseudomonas aeruginosa/enzimologia , Pseudomonas aeruginosa/isolamento & purificação , Sequências Repetitivas de Ácido Nucleico , beta-Lactamases/genéticaRESUMO
Salmonella are facultative intracellular pathogens. Salmonella infection occurs mainly by expression of two Salmonella pathogenicity Islands (SPI-1 and SPI-2). SPI-1 encodes transcriptional factors that participate in the expression of virulence factors encoded in the island. However, there are transcriptional factors encoded outside the island that also participate in the expression of SPI-1-encoded genes. Upon infection, bacteria are capable of avoiding the host immune response with several strategies that involve several virulence factors under the control of transcriptional regulators. Interestingly, LeuO a transcriptional global regulator which is encoded outside of any SPI, is proposed to be part of a complex regulatory network that involves expression of several genes that help bacteria to survive stress conditions and, also, induces the expression of porins that have been shown to be immunogens and can thus be considered as antigenic candidates for acellular vaccines. Hence, the understanding of the LeuO regulon implies a role of bacterial genetic regulation in determining the host immune response.
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Salmonella enterica serovar Typhi (S. Typhi) is the causal agent of typhoid fever, a disease that primarily affects developing countries. Various antigens from this bacterium have been reported to be targets of the immune response. Recently, the S. Typhi genome has been shown to encode two porins--OmpS1 and OmpS2--which are expressed at low levels under in vitro culture conditions. In this study, we demonstrate that immunizing mice with either OmpS1 or OmpS2 induced production of specific, long-term antibody titres and conferred protection against S. Typhi challenge; in particular, OmpS1 was more immunogenic and conferred greater protective effects than OmpS2. We also found that OmpS1 is a Toll-like receptor 4 (TLR4) agonist, whereas OmpS2 is a TLR2 and TLR4 agonist. Both porins induced the production of tumour necrosis factor and interleukin-6, and OmpS2 was also able to induce interleukin-10 production. Furthermore, OmpS1 induced the over-expression of MHC II molecules in dendritic cells and OmpS2 induced the over-expression of CD40 molecules in macrophages and dendritic cells. Co-immunization of OmpS1 or OmpS2 with ovalbumin (OVA) increased anti-OVA antibody titres, the duration and isotype diversity of the OVA-specific antibody response, and the proliferation of T lymphocytes. These porins also had adjuvant effects on the antibody response when co-immunized with either the Vi capsular antigen from S. Typhi or inactivated 2009 pandemic influenza A(H1N1) virus [A(H1N1)pdm09]. Taken together, the data indicate that OmpS1 and OmpS2, despite being expressed at low levels under in vitro culture conditions, are potent protective immunogens with intrinsic adjuvant properties.
Assuntos
Adjuvantes Imunológicos , Anticorpos Antibacterianos/sangue , Proteínas da Membrana Bacteriana Externa/imunologia , Porinas/imunologia , Vacinas contra Salmonella/imunologia , Salmonella typhi/imunologia , Febre Tifoide/prevenção & controle , Adjuvantes Imunológicos/administração & dosagem , Adjuvantes Imunológicos/genética , Animais , Proteínas da Membrana Bacteriana Externa/administração & dosagem , Proteínas da Membrana Bacteriana Externa/genética , Células Dendríticas/imunologia , Relação Dose-Resposta a Droga , Feminino , Células HEK293 , Antígenos de Histocompatibilidade Classe II/metabolismo , Humanos , Imunização , Vírus da Influenza A Subtipo H1N1/imunologia , Vacinas contra Influenza/imunologia , Interleucina-10/metabolismo , Interleucina-6/metabolismo , Ativação Linfocitária , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Ovalbumina/imunologia , Polissacarídeos Bacterianos/imunologia , Porinas/administração & dosagem , Porinas/genética , Vacinas contra Salmonella/administração & dosagem , Vacinas contra Salmonella/genética , Salmonella typhi/genética , Linfócitos T/imunologia , Fatores de Tempo , Receptor 2 Toll-Like/agonistas , Receptor 2 Toll-Like/metabolismo , Receptor 4 Toll-Like/agonistas , Receptor 4 Toll-Like/metabolismo , Transfecção , Fator de Necrose Tumoral alfa/metabolismo , Febre Tifoide/sangue , Febre Tifoide/imunologia , Febre Tifoide/microbiologiaRESUMO
Recentemente, o bis-(3',5')-di-guanosina monofosfato cíclico (c-di-GMP) surgiu como uma importante molécula sinalizadora nas bactérias. Essa molécula foi identificada como uma das responsáveis pelo controle do comportamento bacteriano e está relacionada com a patogenicidade e a adaptação de diversas bactérias, coordenando a expressão de genes envolvidos com virulência, motilidade e formação de biofilme. O mecanismo pelo qual c-diGMP atua vem sendo motivo de estudo de vários grupos de pesquisa nos últimos anos. Já foi demonstrado o papel dessa molécula em diferentes etapas do controle da expressão gênica. Acredita-se que a manipulação dos níveis de c-di-GMP pode ser uma nova abordagem terapêutica contra bactérias patogênicas. Pseudomonas aeruginosa é uma proteobactéria do grupo gama, que atua como um patógeno oportunista, causando infecções em pacientes imunocomprometidos, sendo o maior causador de infecções crônicas em pacientes portadores de fibrose cística. O genoma de P. aeruginosa PA14 apresenta vários genes que codificam proteínas envolvidas no metabolismo e/ou ligação de c-di-GMP, o que pode indicar um amplo papel regulatório deste nucleotídeo nessa bactéria. Uma associação infundada entre níveis elevados de c-di-GMP e a resistência aos antibióticos é geralmente assumida, já que altos níveis de c-di-GMP levam à formação de biofilme, que é comprovadamente um modo de crescimento mais resistente. Nesse trabalho, utilizando uma abordagem proteômica, mostramos que Pseudomonas aeruginosa PA14 regula a expressão de cinco porinas em resposta a variações nos níveis de c-di-GMP, independentemente dos níveis de mRNA. Uma dessas porinas, OprD, é responsável pela entrada do antibiótico ß-lactâmico imipenem na célula e é menos abundante em condições de alto c-di-GMP. Também demonstramos que linhagens com altos níveis de c-di-GMP apresentam uma vantagem competitiva de crescimento em relação a linhagens com níveis mais baixo de c-di-GMP quando crescidas em meio contendo imipenem. Em contraste, observamos que células planctônicas com elevados níveis c-di-GMP são mais sensíveis a tobramicina. Em conjunto, estes resultados mostram que c-di-GMP pode regular a resistência a antibióticos em sentidos opostos, e independentemente do crescimento em biofilme
Following the genomic era, a large number of genes coding for enzymes predicted to synthesize and degrade 3'-5'-cyclic diguanylic acid (c-di-GMP) was found in most bacterial genomes and this dinucleotide emerged as an important intracellular signal molecule controlling bacterial behavior. Diverse molecular mechanisms have been described as targets for c-di-GMP, but several questions remain to be addressed. An association between high c-di-GMP levels and antibiotic resistance is largely assumed, since high c-di-GMP upregulates biofilm formation and the biofilm mode of growth leads to enhanced antibiotic resistance; however, a clear understanding of this correlation is missing. Pseudomonas aeruginosa is a versatile gamma-proteobacterium that behaves as an opportunistic pathogen to a broad range of hosts. The ability of P. aeruginosa to form biofilms contributes to its virulence and adaptation to different environments. The P. aeruginosa PA14 genome presents several genes encoding proteins involved in metabolism or binding to c-di-GMP, which may indicate a wide regulatory role of this nucleotide in this bacterium. Here, using a proteomic approach, we show that Pseudomonas aeruginosa PA14 regulates the amount of five porins in response to c-di-GMP levels, irrespective of their mRNA levels. One of these porins is OprD, decreased in high c-di-GMP conditions, which is responsible for the uptake of the ß-lactam antibiotic imipenem. We also demonstrate that this difference leads strains with high c-di-GMP to be more resistant to imipenem even when growing as planktonic cells, giving them a competitive advantage over cells with low c-di-GMP. Contrastingly, we found that planktonic cells with high c-di-GMP levels are more sensitive to aminoglycosides antibiotics. Together, these findings show that c-di-GMP levels can regulate the antibiotic resistance to different drugs in opposite ways and irrespective of a biofilm mode of growth
Assuntos
Animais , Masculino , Feminino , Camundongos , GMP Cíclico/análise , Porinas/análise , Western Blotting/métodos , Resistência Microbiana a Medicamentos , Expressão Gênica/genética , Microscopia de Fluorescência/métodos , Pseudomonas aeruginosa/genética , Reação em Cadeia da Polimerase em Tempo Real/métodosRESUMO
Relatos mundiais têm documentado a problemática da endemicidade de isolados clínicos de Pseudomonas aeruginosa multirresistente (MDR) aliada a elevados índices de morbidade/mortalidade. No Brasil, surtos de infecção ocasionados por P. aeruginosa têm sido relacionados com uma disseminação clonal da espécie. Atualmente, as opções terapêuticas para o tratamento das infecções causadas por esse microrganismo são limitadas, muitas vezes restringindo-se ao uso de carbapenêmicos (p. ex., imipenem [IPM]). Assim, a resistência ao IPM é uma questão de saúde pública, uma vez que esse antibiótico é empregado como último recurso no tratamento de infecções de origem hospitalar, causadas por bactérias Gram-negativas multirresistentes. No Brasil, os principais mecanismos relacionados com fenótipos multirresistentes de P. aeruginosa são produção de metalobetalactamase (MBL) do tipo SPM-1, presença de metilase 16S rRNA RmtD, perda de porina OprD e superexpressão de bombas de efluxo, o que pode explicar os altos índices de resistência a carbapenêmicos e aminoglicosídeos. A emergência de cepas com essas características é preocupante, tendo em vista a escassez de terapias efetivas no tratamento de infecções por esse patógeno. Finalmente, com base em relatos nacionais, publicados por diferentes grupos de pesquisa, podemos deduzir que a convergência de múltiplos mecanismos de resistência em P. aeruginosa tem sido um evento favorável para a seleção de diferentes clones endêmicos multirresistentes disseminados no Brasil.
Global reports have documented the endemicity of multidrug-resistant (MDR) Pseudomonas aeruginosa associated with high levels of morbidity/mortality. In Brazil, outbreaks of MDR P. aeruginosa have been related to clonal dissemination. Currently, therapeutic options for the treatment of these infections are restricted to carbapenemic antibiotics (i.e., imipenem [IPM]). Thus, carbapenem resistance is a public health issue, since carbapenems are considered the last resort to nosocomial infections caused by MDR Gram-negative bacteria. In Brazil, the main mechanisms associated with MDR P. aeruginosa phenotypes are metallo-betalactamase (MBL) production (SPM-1 enzyme), presence of 16S rRNA methylase RmtD, loss of OprD porin, and overexpression of efflux pumps, which may explain the high level of carbapenem and aminoglycoside resistance. Accordingly, the emergence and dissemination of MDR strains is worrisome. Finally, based on national reports published by different groups of investigators, it is deduced that the convergence of multiple mechanisms of P. aeruginosa resistance has played a major role in the selection of endemic MDR clones widespread in Brazil.
Assuntos
Farmacorresistência Bacteriana , Doenças Endêmicas , Porinas , Pseudomonas aeruginosaRESUMO
The recognition of bacterial components on the intestinal epithelial cells occurs through the toll-like receptors and is followed by the induction of an effective innate immune response. We analyzed receptor expression and signaling pathways involved in activation of human colon adenocarcinoma cells after stimulation with porins and LPS of Shigella flexneri. We also analyzed the expression and production of some cytokines, of intercellular adhesion molecule-1, of antimicrobial peptides human ²-defensins, and of the inducible form of nitric oxide synthase. Our data demonstrate that TLR2 is involved in porin recognition, whereas TLR4 with MD2, is required for LPS recognition.
O reconhecimento de componentes bacterianos nas células epiteliais intestinais ocorre através de receptores toll-like e é seguido de indução de uma resposta imune inata efetiva. Neste estudo foram analisadas as vias de expressão do receptor e sinalização envolvidas na ativação de células humanas de adenocarcinoma do colon após a estimulação com porinas e LPS de Shigella flexneri. Foram também analisadas a expressão e produção de algumas citoquinas, da molécula -1 de adesão intercelular, de ²-defensinas humanas a peptídios antimicrobianos e da forma indutível de oxido nítrico sintase. Os resultados demonstraram que TLR-2 está envolvido no reconhecimento de porinas, enquanto TLR4 com MD2 é necessário para o reconhecimento de LPS.
RESUMO
The recognition of bacterial components on the intestinal epithelial cells occurs through the toll-like receptors and is followed by the induction of an effective innate immune response. We analyzed receptor expression and signaling pathways involved in activation of human colon adenocarcinoma cells after stimulation with porins and LPS of Shigella flexneri. We also analyzed the expression and production of some cytokines, of intercellular adhesion molecule-1, of antimicrobial peptides human ß-defensins, and of the inducible form of nitric oxide synthase. Our data demonstrate that TLR2 is involved in porin recognition, whereas TLR4 with MD2, is required for LPS recognition.
RESUMO
The recognition of bacterial components on the intestinal epithelial cells occurs through the toll-like receptors and is followed by the induction of an effective innate immune response. We analyzed receptor expression and signaling pathways involved in activation of human colon adenocarcinoma cells after stimulation with porins and LPS of Shigella flexneri. We also analyzed the expression and production of some cytokines, of intercellular adhesion molecule-1, of antimicrobial peptides human ²-defensins, and of the inducible form of nitric oxide synthase. Our data demonstrate that TLR2 is involved in porin recognition, whereas TLR4 with MD2, is required for LPS recognition.
O reconhecimento de componentes bacterianos nas células epiteliais intestinais ocorre através de receptores toll-like e é seguido de indução de uma resposta imune inata efetiva. Neste estudo foram analisadas as vias de expressão do receptor e sinalização envolvidas na ativação de células humanas de adenocarcinoma do colon após a estimulação com porinas e LPS de Shigella flexneri. Foram também analisadas a expressão e produção de algumas citoquinas, da molécula -1 de adesão intercelular, de ²-defensinas humanas a peptídios antimicrobianos e da forma indutível de oxido nítrico sintase. Os resultados demonstraram que TLR-2 está envolvido no reconhecimento de porinas, enquanto TLR4 com MD2 é necessário para o reconhecimento de LPS.