RESUMEN

The use of monoclonal antibodies for the control of drug resistant nosocomial bacteria may alleviate a reliance on broad spectrum antimicrobials for treatment of infection. We identify monoclonal antibodies that may prevent infection caused by carbapenem resistant Acinetobacter baumannii. We use human immune repertoire mice (Kymouse platform mice) as a surrogate for human B cell interrogation to establish an unbiased strategy to probe the antibody-accessible target landscape of clinically relevant A. baumannii. After immunisation of the Kymouse platform mice with A. baumannii derived outer membrane vesicles (OMV) we identify 297 antibodies and analyse 26 of these for functional potential. These antibodies target lipooligosaccharide (OCL1), the Oxa-23 protein, and the KL49 capsular polysaccharide. We identify a single monoclonal antibody (mAb1416) recognising KL49 capsular polysaccharide to demonstrate prophylactic in vivo protection against a carbapenem resistant A. baumannii lineage associated with neonatal sepsis mortality in Asia. Our end-to-end approach identifies functional monoclonal antibodies with prophylactic potential against major lineages of drug resistant bacteria accounting for phylogenetic diversity and clinical relevance without existing knowledge of a specific target antigen. Such an approach might be scaled for a additional clinically important bacterial pathogens in the post-antimicrobial era.

Asunto(s)

Infecciones por Acinetobacter , Acinetobacter baumannii , Anticuerpos Monoclonales , Ratones Transgénicos , Acinetobacter baumannii/inmunología , Acinetobacter baumannii/genética , Animales , Humanos , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/farmacología , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/prevención & control , Infecciones por Acinetobacter/microbiología , Ratones , Antibacterianos/farmacología , Anticuerpos Antibacterianos/inmunología , Femenino , Carbapenémicos/farmacología , Farmacorresistencia Bacteriana/inmunología , Farmacorresistencia Bacteriana/genética , Lipopolisacáridos/inmunología

RESUMEN

Acinetobacter baumannii is a gram-negative bacillus prevalent in nature, capable of thriving under various environmental conditions. As an opportunistic pathogen, it frequently causes nosocomial infections such as urinary tract infections, bacteremia, and pneumonia, contributing to increased morbidity and mortality in clinical settings. Consequently, developing novel vaccines against Acinetobacter baumannii is of utmost importance. In our study, we identified 10 highly conserved antigenic proteins from the NCBI and UniProt databases for epitope mapping. We subsequently screened and selected 8 CTL, HTL, and LBL epitopes, integrating them into three distinct vaccines constructed with adjuvants. Following comprehensive evaluations of immunological and physicochemical parameters, we conducted molecular docking and molecular dynamics simulations to assess the efficacy and stability of these vaccines. Our findings indicate that all three multi-epitope mRNA vaccines designed against Acinetobacter baumannii are promising; however, further animal studies are required to confirm their reliability and effectiveness.

Asunto(s)

Acinetobacter baumannii , Vacunas Bacterianas , Biología Computacional , Acinetobacter baumannii/inmunología , Acinetobacter baumannii/genética , Vacunas Bacterianas/inmunología , Vacunas Bacterianas/genética , Biología Computacional/métodos , Epítopos/inmunología , Epítopos/química , Simulación del Acoplamiento Molecular , Infecciones por Acinetobacter/prevención & control , Infecciones por Acinetobacter/inmunología , Mapeo Epitopo , Vacunas de ARNm , Simulación de Dinámica Molecular , Humanos , ARN Mensajero/genética , ARN Mensajero/inmunología , Antígenos Bacterianos/inmunología , Antígenos Bacterianos/genética , Proteínas Bacterianas/inmunología , Proteínas Bacterianas/genética , Proteínas Bacterianas/química

RESUMEN

Due to its antimicrobial resistance characteristics, the World Health Organization (WHO) classifies A. baumannii as one of the critical priority pathogens for the development of new therapeutic strategies. Vaccination has been approached as an interesting strategy to overcome the lack of effective antimicrobials and the long time required to develop and approve new drugs. In this study, we aimed to evaluate as a vaccine the hypothetical adhesin protein CAM87009.1 in its recombinant format (rCAM87009.1) associated with aluminum hydroxide (Alhydrogel®) or biogenic silver nanoparticles (bio-AgNP) as adjuvant components against lethal infection by A. baumannii MDR strain. Both vaccine formulations were administered in three doses intramuscularly in BALB/c murine models and the vaccinated animals were tested in a challenge assay with A. baumannii MDR strain (DL100). rCAM87009.1 protein associated with both adjuvants was able to protect 100 % of animals challenged with the lethal strain during the challenge period. After the euthanasia of the animals, no A. baumannii colonies were detected in the lungs of animals vaccinated with the rCAM87009.1 protein in both formulations. Since the first immunization, high IgG antibody titers were observed (1:819,200), with results being statistically similar in both vaccine formulations evaluated. rCAM87009.1 associated with both adjuvants was capable of inducing at least one class of isotypes associated with the processes of neutralization (IgG2b and IgA for bio-AgNP and Alhydrogel®, respectively), opsonization (IgG1 in both vaccines) and complement activation (IgM and IgG3 for bio-AgNP and Alhydrogel®, respectively). Furthermore, reduced tissue damage was observed in animals vaccinated with rCAM87009.1 + bio-AgNP when compared to animals vaccinated with Alhydrogel®. Our results indicate that the rCAM87009.1 protein associated with both bio-AgNP and Alhydrogel® are combinations capable of promoting immunity against infections caused by A. baumannii MDR. Additionally, we demonstrate the potential of silver nanoparticles as alternative adjuvant molecules to the use of aluminum salts.

Asunto(s)

Infecciones por Acinetobacter , Acinetobacter baumannii , Adhesinas Bacterianas , Adyuvantes Inmunológicos , Anticuerpos Antibacterianos , Nanopartículas del Metal , Ratones Endogámicos BALB C , Plata , Animales , Plata/administración & dosificación , Plata/farmacología , Acinetobacter baumannii/inmunología , Acinetobacter baumannii/efectos de los fármacos , Ratones , Infecciones por Acinetobacter/prevención & control , Infecciones por Acinetobacter/inmunología , Adhesinas Bacterianas/inmunología , Adyuvantes Inmunológicos/administración & dosificación , Adyuvantes Inmunológicos/farmacología , Anticuerpos Antibacterianos/sangre , Anticuerpos Antibacterianos/inmunología , Farmacorresistencia Bacteriana Múltiple , Vacunas Bacterianas/inmunología , Vacunas Bacterianas/administración & dosificación , Compuestos de Alumbre/administración & dosificación , Femenino , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Modelos Animales de Enfermedad

RESUMEN

Acinetobacter baumannii is an opportunistic bacterium that causes infection in several sites. Carbapenem-resistant A. baumannii strains (CRAb) lead the World Health Organization's list of 12 pathogens considered a priority for developing new antimicrobials. The pathogenicity of A. baumannii is related to the different virulence factors employed in the colonization of biotic and abiotic surfaces, biofilm formation and multidrug resistance. We analyze the outer membrane protein FilF from A. baumannii in silico and produce it in recombinant form (rFilF). rFilF protein was successfully expressed in Escherichia coli BL21 Star in an insoluble form. Immunization with rFilF induced significant anti-rFilF IgG antibody production in mice, detected by indirect enzyme-linked immunosorbent assay, since the first evaluation until 49th. On the last experimentation day, the predominant immunoglobulin found was IgG1 followed by IgG2a, IgG2b, IgM, IgG3, and IgA. We observe that interleukins 4 and 10 show significant production after the 28th day of experimentation in mice immunized with rFilF. Anti-rFilF pAbs were able to inhibit biofilm formation in nine CRAb strains evaluated, and in the standard strain ATCC® 19606. These results demonstrate the anti-biofilm activity of anti-rFilF antibodies, promising in the development of a non-antibiotic approach based on the control of CRAb strains.

Asunto(s)

Acinetobacter baumannii , Anticuerpos Antibacterianos , Biopelículas , Carbapenémicos , Biopelículas/efectos de los fármacos , Acinetobacter baumannii/inmunología , Acinetobacter baumannii/efectos de los fármacos , Animales , Anticuerpos Antibacterianos/inmunología , Carbapenémicos/farmacología , Ratones , Inmunoglobulina G/inmunología , Antibacterianos/farmacología , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/microbiología , Proteínas Recombinantes/inmunología , Proteínas Recombinantes/farmacología , Proteínas Recombinantes/genética , Ratones Endogámicos BALB C , Femenino , Escherichia coli/genética , Escherichia coli/inmunología , Proteínas de la Membrana Bacteriana Externa/inmunología , Proteínas de la Membrana Bacteriana Externa/genética

RESUMEN

Nosocomial infections caused by Acinetobacter baumannii (A. baumannii) nosocomial infections caused by Acinetobacter baumannii (A. baumannii) are considered as a global serious problem in hospitalized patients because of emerging antibiotic resistance. Immunotherapy approaches are promising to prevent such infections. In our previous study, five antigenic epitopes of outer membrane protein A (OmpA), as the most dangerous virulence molecule in A. baumanii, were predicted in silico. In this study, the investigators evaluated some immunological aspects of the peptides. Five peptides were separately injected into C5BL/6 mice; then the cytokine production (interleukin-4 and interferon-gamma) of splenocytes and opsonophagocytic activity of immunized serum were assessed. To identify the protective function of the peptides, animal models of sepsis and pneumonia infections were actively and passively immunized with selected peptides and pooled sera of immunized mice, respectively. Then, survival rates of them were compared with the non-infected controls. Based on the results, activated spleen cells in P127 peptide-immunized mice exhibited an increase level of IFN-γ compared with the other experimental groups, but not about the IL-4 concentration. The results of opsonophagocytic assay revealed an appropriate killing activity of produced antibodies against A. baumannii in a dose-dependent manner. Further, the survival rates of the mice under passive immunization with the immunized sera or active immunization with P127 peptide were significantly more than those in the control group. Moreover, the survival rate of the P127 peptide immunized group was considerably higher than that among the other peptide-immunized group. In conclusion, findings indicated that peptides derived from outer membrane protein-A can be used as a promising tool for designing the epitope-based vaccines against infections caused by A. baumannii.

Asunto(s)

Infecciones por Acinetobacter/prevención & control , Acinetobacter baumannii/inmunología , Proteínas de la Membrana Bacteriana Externa/inmunología , Vacunas Bacterianas/inmunología , Epítopos/inmunología , Neumonía Bacteriana/prevención & control , Sepsis/prevención & control , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/mortalidad , Animales , Antígenos Bacterianos/inmunología , Vacunas Bacterianas/administración & dosificación , Citocinas/metabolismo , Modelos Animales de Enfermedad , Interacciones Huésped-Patógeno/inmunología , Inmunización , Ratones , Neumonía Bacteriana/inmunología , Neumonía Bacteriana/mortalidad , Pronóstico , Sepsis/inmunología , Sepsis/mortalidad , Resultado del Tratamiento

RESUMEN

The human pathogen Acinetobacter baumannii produces and utilizes acinetobactin for iron assimilation. Although two isomeric structures of acinetobactin, one featuring an oxazoline (Oxa) and the other with an isoxazolidinone (Isox) at the core, have been identified, their differential roles as virulence factors for successful infection have yet to be established. This study provides direct evidence that Oxa supplies iron more efficiently than Isox, primarily owing to its specific recognition by the cognate outer membrane receptor, BauA. The other components in the acinetobactin uptake machinery appear not to discriminate these isomers. Interestingly, Oxa was found to form a stable iron complex that is resistant to release of the chelated iron upon competition by Isox, despite their comparable apparent affinities to Fe(III). In addition, both Oxa and Isox were found to be competent iron chelators successfully scavenging iron from host metal sequestering proteins responsible for nutritional immunity. These observations collectively led us to propose a new model for acinetobactin-based iron assimilation at infection sites. Namely, Oxa is the principal siderophore mediating the core Fe(III) supply chain for A. baumannii, whereas Isox plays a minor role in the iron delivery and, alternatively, functions as an auxiliary iron collector that channels the iron pool toward Oxa. The unique siderophore utilization mechanism proposed here represents an intriguing strategy for pathogen adaptation under the various nutritional stresses encountered at infection sites. IMPORTANCE Acinetobacter baumannii has acquired antibiotic resistance at an alarming rate, and it is becoming a serious threat to society, particularly due to the paucity of effective treatment options. Acinetobactin is a siderophore of Acinetobacter baumannii, responsible for active iron supply, and it serves as a key virulence factor to counter host nutritional immunity during infection. While two acinetobactin isomers were identified, their distinctive roles for successful infection of Acinetobacter baumannii remained unsettled. This study clearly identified the isomer containing an oxazoline core as the principal siderophore based on comparative analysis of the specificity of the acinetobactin uptake machinery, the stability of the corresponding iron complexes, and the iron scavenging activity against the host iron sequestering proteins. Our findings are anticipated to stimulate efforts to discover a potent antivirulence agent against Acinetobacter baumannii that exploits the acinetobactin-based iron assimilation mechanism.

Asunto(s)

Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/metabolismo , Imidazoles/química , Imidazoles/metabolismo , Oxazoles/química , Oxazoles/metabolismo , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/metabolismo , Acinetobacter baumannii/química , Acinetobacter baumannii/genética , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Humanos , Hierro/metabolismo , Isomerismo , Sideróforos/química , Sideróforos/metabolismo

RESUMEN

Vaccination strategies for rapid protection against multidrug-resistant bacterial infection are very important, especially for hospitalized patients who have high risk of exposure to these bacteria. However, few such vaccination strategies exist due to a shortage of knowledge supporting their rapid effect. Here, we demonstrated that a single intranasal immunization of inactivated whole cell of Acinetobacter baumannii elicits rapid protection against broad A. baumannii-infected pneumonia via training of innate immune response in Rag1-/- mice. Immunization-trained alveolar macrophages (AMs) showed enhanced TNF-α production upon restimulation. Adoptive transfer of immunization-trained AMs into naive mice mediated rapid protection against infection. Elevated TLR4 expression on vaccination-trained AMs contributed to rapid protection. Moreover, immunization-induced rapid protection was also seen in Pseudomonas aeruginosa and Klebsiella pneumoniae pneumonia models, but not in Staphylococcus aureus and Streptococcus pneumoniae model. Our data reveal that a single intranasal immunization induces rapid and efficient protection against certain Gram-negative bacterial pneumonia via training AMs response, which highlights the importance and the possibility of harnessing trained immunity of AMs to design rapid-effecting vaccine.

Asunto(s)

Infecciones por Acinetobacter/prevención & control , Acinetobacter baumannii/inmunología , Vacunas Bacterianas/administración & dosificación , Infecciones por Klebsiella/prevención & control , Klebsiella pneumoniae/inmunología , Macrófagos Alveolares/efectos de los fármacos , Neumonía Bacteriana/prevención & control , Infecciones por Pseudomonas/prevención & control , Pseudomonas aeruginosa/inmunología , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/microbiología , Administración Intranasal , Traslado Adoptivo , Animales , Células Cultivadas , Modelos Animales de Enfermedad , Femenino , Proteínas de Homeodominio/genética , Inmunidad Innata/efectos de los fármacos , Infecciones por Klebsiella/inmunología , Infecciones por Klebsiella/microbiología , Macrófagos Alveolares/inmunología , Macrófagos Alveolares/microbiología , Macrófagos Alveolares/trasplante , Ratones Endogámicos C57BL , Ratones Noqueados , Neumonía Bacteriana/inmunología , Neumonía Bacteriana/microbiología , Infecciones por Pseudomonas/inmunología , Infecciones por Pseudomonas/microbiología , Factores de Tiempo , Receptor Toll-Like 4/genética , Receptor Toll-Like 4/metabolismo , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismo , Vacunación , Vacunas de Productos Inactivados/administración & dosificación

RESUMEN

Extremely drug-resistant (XDR) Acinetobacter baumannii is a notorious and frequently encountered pathogen demanding novel therapeutic interventions. An initial monoclonal antibody (MAb), C8, raised against A. baumannii capsule, proved a highly effective treatment against a minority of clinical isolates. To overcome this limitation, we broadened coverage by developing a second antibody for use in a combination regimen. We sought to develop an additional anti-A. baumannii MAb through hybridoma technology by immunizing mice with sublethal inocula of virulent, XDR clinical isolates not bound by MAb C8. We identified a new antibacterial MAb, 65, which bound to strains in a pattern distinct from and complementary to that of MAb C8. MAb 65 enhanced macrophage opsonophagocytosis of targeted strains and markedly improved survival in lethal bacteremic sepsis and aspiration pneumonia murine models of A. baumannii infection. MAb 65 was also synergistic with colistin, substantially enhancing protection compared to monotherapy. Treatment with MAb 65 significantly reduced blood bacterial density, ameliorated cytokine production (interleukin-1ß [IL-1ß], IL-6, IL-10, and tumor necrosis factor), and sepsis biomarkers. We describe a novel MAb targeting A. baumannii that broadens immunotherapeutic strain coverage, is highly potent and effective, and synergistically improves outcomes in combination with antibiotics.

Asunto(s)

Infecciones por Acinetobacter/inmunología , Acinetobacter baumannii/inmunología , Anticuerpos Monoclonales/inmunología , Infecciones por Acinetobacter/sangre , Infecciones por Acinetobacter/microbiología , Animales , Antibacterianos/inmunología , Anticuerpos Antibacterianos/inmunología , Biomarcadores/sangre , Colistina/inmunología , Citocinas/sangre , Citocinas/inmunología , Farmacorresistencia Bacteriana Múltiple/inmunología , Ratones , Pruebas de Sensibilidad Microbiana/métodos , Sepsis/sangre , Sepsis/inmunología , Sepsis/microbiología

RESUMEN

Acinetobacter baumannii (A. baumannii), an opportunistic, gram-negative pathogen, has evoked the interest of the medical community throughout the world because of its ability to cause nosocomial infections, majorly infecting those in intensive care units. It has also drawn the attention of researchers due to its evolving immune evasion strategies and increased drug resistance. The emergence of multi-drug-resistant-strains has urged the need to explore novel therapeutic options as an alternative to antibiotics. Due to the upsurge in antibiotic resistance mechanisms exhibited by A. baumannii, the current therapeutic strategies are rendered less effective. The aim of this study is to explore novel therapeutic alternatives against A. baumannii to control the ailed infection. In this study, a computational framework is employed involving, pan genomics, subtractive proteomics and reverse vaccinology strategies to identify core promiscuous vaccine candidates. Two chimeric vaccine constructs having B-cell derived T-cell epitopes from prioritized vaccine candidates; APN, AdeK and AdeI have been designed and checked for their possible interactions with host BCR, TLRs and HLA Class I and II Superfamily alleles. These vaccine candidates can be experimentally validated and thus contribute to vaccine development against A. baumannii infections.

Asunto(s)

Acinetobacter baumannii/inmunología , Vacunas Bacterianas/inmunología , Infecciones por Acinetobacter/inmunología , Secuencia de Aminoácidos , Antibacterianos/inmunología , Biología Computacional/métodos , Infección Hospitalaria/inmunología , Epítopos/inmunología , Genoma Bacteriano/inmunología , Genómica/métodos , Proteómica/métodos , Vacunología/métodos

RESUMEN

Vaccines and monoclonal antibodies are promising approaches for preventing and treating infections caused by multidrug resistant Acinetobacter baumannii. However, only partial protection has been achieved with many previously tested protein antigens, which suggests that vaccines incorporating multiple antigens may be necessary in order to obtain high levels of protection. Several aspects that use the wealth of omic data available for A. baumannii have not been fully exploited for antigen identification. In this study, the use of fractionated proteomic and computational data from ~4,200 genomes increased the number of proteins potentially accessible to the humoral response to 8,824 non-redundant proteins in the A. baumannii panproteome. Among them, 59% carried predicted B-cell epitopes and T-cell epitopes recognized by two or more alleles of the HLA class II DP supertype. Potential cross-reactivity with human proteins was detected for 8.9% of antigens at the protein level and 2.7% at the B-cell epitope level. Individual antigens were associated with different infection types by genomic, transcriptomic or functional analyses. High intra-clonal genome density permitted the identification of international clone II as a "vaccitype", in which 20% of identified antigens were specific to this clone. Network-based centrality measurements were used to identify multiple immunologic nodes. Data were formatted, unified and stored in a data warehouse database, which was subsequently used to identify synergistic antigen combinations for different vaccination strategies. This study supports the idea that integration of multi-omic data and fundamental knowledge of the pathobiology of drug-resistant bacteria can facilitate the development of effective multi-antigen vaccines against these challenging infections.

Asunto(s)

Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/inmunología , Vacunas Bacterianas/inmunología , Farmacorresistencia Bacteriana/inmunología , Epítopos/inmunología , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/prevención & control , Acinetobacter baumannii/genética , Antígenos Bacterianos/inmunología , Epítopos/química , Epítopos/genética , Genes Bacterianos , Genoma Bacteriano , Genómica/métodos , Humanos

RESUMEN

Monoclonal antibodies (mAbs) are gaining significant momentum as novel therapeutics for infections caused by antibiotic-resistant bacteria. We evaluated the mechanism by which antibacterial mAb therapy protects against Acinetobacter baumannii infections. Anticapsular mAb enhanced macrophage opsonophagocytosis and rescued mice from lethal infections by harnessing complement, macrophages, and neutrophils; however, the degree of bacterial burden did not correlate with survival. Furthermore, mAb therapy reduced proinflammatory (interleukin-1ß [IL-1ß], IL-6, tumor necrosis factor-α [TNF-α]) and anti-inflammatory (IL-10) cytokines, which correlated inversely with survival. Although disrupting IL-10 abrogated the survival advantage conferred by the mAb, IL-10-knockout mice treated with mAb could still survive if TNF-α production was suppressed directly (via anti-TNF-α neutralizing antibody) or indirectly (via macrophage depletion). Thus, even for a mAb that enhances microbial clearance via opsonophagocytosis, clinical efficacy required modulation of pro- and anti-inflammatory cytokines. These findings may inform future mAb development targeting bacteria that trigger the sepsis cascade.

Asunto(s)

Infecciones por Acinetobacter/tratamiento farmacológico , Infecciones por Acinetobacter/inmunología , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/inmunología , Anticuerpos Monoclonales/inmunología , Anticuerpos Monoclonales/uso terapéutico , Inmunomodulación , Infecciones por Acinetobacter/microbiología , Animales , Antibacterianos , Citocinas/sangre , Citocinas/inmunología , Interleucina-10 , Ratones , Opsonización , Inhibidores del Factor de Necrosis Tumoral , Factor de Necrosis Tumoral alfa

RESUMEN

BACKGROUND: The development of vaccines is a promising and cost-effective strategy to prevent emerging multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii) infections. The purpose of this study was to prepare a multiepitope peptide nanovaccine and evaluate its immunogenicity and protective effect in BALB/c mice. METHODS: The B-cell and T-cell epitopes of Omp22 from A. baumannii were predicted using bioinformatics methods and identified by immunological experiments. The optimal epitopes were conjugated in series by 6-aminocaproic acid and chemically synthesized multiepitope polypeptide rOmp22. Then, rOmp22 was encapsulated by chitosan (CS) and poly (lactic-co-glycolic) acid (PLGA) to prepare CS-PLGA-rOmp22 nanoparticles (NPs). The immunogenicity and immunoprotective efficacy of the vaccine were evaluated in BALB/c mice. RESULTS: CS-PLGA-rOmp22 NPs were small (mean size of 272.83 nm) with apparently spherical structures, positively charged (4.39 mV) and nontoxic to A549 cells. A high encapsulation efficiency (54.94%) and a continuous slow release pattern were achieved. Compared with nonencapsulated rOmp22, CS-PLGA-rOmp22 immunized BALB/c mice induced higher levels of rOmp22-specific IgG in serum and IFN-γ in splenocyte supernatant. Additionally, lung injury and bacterial burdens in the lung and blood were suppressed, and potent protection (57.14%-83.3%) against acute lethal intratracheal A. baumannii challenge was observed in BALB/c mice vaccinated with CS-PLGA-rOmp22. CONCLUSION: CS-PLGA-rOmp22 NPs elicited specific IgG antibodies, Th1 cellular immunity and protection against acute lethal intratracheal A. baumannii challenge. Our results indicate that this nanovaccine is a desirable candidate for preventing A. baumannii infection.

Asunto(s)

Infecciones por Acinetobacter/inmunología , Acinetobacter baumannii/inmunología , Vacunas Bacterianas/inmunología , Quitosano/química , Epítopos/inmunología , Nanopartículas/química , Péptidos/inmunología , Copolímero de Ácido Poliláctico-Ácido Poliglicólico/química , Células A549 , Infecciones por Acinetobacter/sangre , Infecciones por Acinetobacter/microbiología , Secuencia de Aminoácidos , Animales , Anticuerpos Antibacterianos/inmunología , Carga Bacteriana , Peso Corporal , Epítopos/química , Femenino , Humanos , Inmunidad Humoral , Inmunización , Inmunoglobulina G/inmunología , Interferón gamma/metabolismo , Interleucina-4/metabolismo , Pulmón/inmunología , Pulmón/microbiología , Pulmón/patología , Ratones , Ratones Endogámicos BALB C , Nanopartículas/ultraestructura , Péptidos/química , Proteínas Recombinantes/aislamiento & purificación , Bazo/patología , Análisis de Supervivencia

RESUMEN

Sepsis is caused by organ dysfunction initiated by an unrestrained host immune response to infection. The emergence of antibiotic-resistant bacteria has rapidly increased in the last decades and has stimulated a firm research platform to combat infections caused by antibiotic-resistant bacteria that cannot be eradicated with conventional antibiotics. Strategies like epigenetic regulators such as lysine demethylase (Kdm) has received attention as a new target. Thus, we sought to investigate the epigenetic mechanisms in sepsis pathophysiology with the aim of discovering new concepts for treatment. A transcriptome analysis of dendritic cells during their inflammatory state identified Kdm as a critical molecule in sepsis regulation. Next, 8-hydroxyquinoline-5-carboxylic acid (IOX1) ability to control endotoxemia induced by Lipopolysaccharide and bacterial sepsis was demonstrated. IOX1 has been shown to regulate endotoxemia and sepsis caused by Escherichia coli and carbapenem-resistant Acinetobacter baumannii and has also contributed to the suppression of multidrug-resistant bacterial growth through the inhibition of DNA Gyrase. These findings show that IOX1 could be a component agent against bacterial sepsis by functioning as a broad-spectrum antibiotic with dual effects.

Asunto(s)

Infecciones por Acinetobacter/tratamiento farmacológico , Antibacterianos/farmacología , Infecciones por Escherichia coli/tratamiento farmacológico , Hidroxiquinolinas/farmacología , Sepsis/tratamiento farmacológico , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/efectos de los fármacos , Animales , Antibacterianos/uso terapéutico , Girasa de ADN/metabolismo , Células Dendríticas/efectos de los fármacos , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Modelos Animales de Enfermedad , Farmacorresistencia Bacteriana Múltiple/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Infecciones por Escherichia coli/inmunología , Infecciones por Escherichia coli/microbiología , Femenino , Histona Demetilasas/antagonistas & inhibidores , Histona Demetilasas/metabolismo , Humanos , Hidroxiquinolinas/uso terapéutico , Ratones , Pruebas de Sensibilidad Microbiana , Simulación del Acoplamiento Molecular , Sepsis/inmunología , Sepsis/microbiología

RESUMEN

Aim: Iron uptake and metabolism pathways are promising targets in vaccine development as an alternative strategy for antibiotics. Methods & methods: HemTR, a putative heme receptor of Acinetobacter baumannii, was expressed and its protectivity against A. baumannii was determined singly or in combination with the siderophore receptor, BauA, in mice. Results: High level of IgG was elicited. There was a delay in mice mortality with reduced bacterial loads in internal organs in the sublethal challenge. Protection was better in the HemTR-BauA group in both lethal and sublethal challenges. Passive transfer of anti-HemTR and anti-BauA partially protected mice against A. baumannii infection. Conclusion: HemTR in combination with other iron receptors could contribute to the development of protective vaccines against A. baumannii.

Asunto(s)

Infecciones por Acinetobacter/prevención & control , Acinetobacter baumannii/inmunología , Proteínas de la Membrana Bacteriana Externa/inmunología , Proteínas Bacterianas/inmunología , Receptores de Superficie Celular/inmunología , Sepsis/prevención & control , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/genética , Animales , Carga Bacteriana , Proteínas de la Membrana Bacteriana Externa/administración & dosificación , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas Bacterianas/administración & dosificación , Proteínas Bacterianas/genética , Vacunas Bacterianas/administración & dosificación , Vacunas Bacterianas/genética , Vacunas Bacterianas/inmunología , Modelos Animales de Enfermedad , Femenino , Hemo/inmunología , Humanos , Ratones , Ratones Endogámicos BALB C , Receptores de Superficie Celular/administración & dosificación , Receptores de Superficie Celular/genética , Sepsis/inmunología , Sepsis/microbiología

RESUMEN

INTRODUCTION: Healthcare-associated infections caused by multidrug-resistant Acinetobacter baumannii are becoming alarming worldwide. However, the pipeline of new antibiotics is very limited. Vaccination is one of the most cost effective and promising strategies to prevent infections and can play an important role in combat multidrug resistance A. baumannii and prevent the development of new drug resistance. AREA COVERED: This review gives an overview of the research and development of A. baumannii vaccines during the past five years (2015-2020), discusses the key progresses and current challenges of the field, and speculates on the future of A. baumannii vaccine development. EXPERT OPINION: Moderate progresses have been made in the research and development of A. baumannii vaccine in the last five years, in particular in the areas of identification of new protein targets, development of multicomponent vaccines, and use of vaccines and antibodies as adjuncts for antibiotics therapies. However, substantial scientific and logistic challenges, such as selection of lead vaccine candidates and formulation, vaccine clinical trials and targeted population, and financial incentives, remain. Thus, innovative strategies will be needed before an A. baumannii vaccine candidate can be brought into late stage of preclinical development in next five years.

Asunto(s)

Infecciones por Acinetobacter/prevención & control , Acinetobacter baumannii , Vacunas Bacterianas , Desarrollo de Vacunas , Infecciones por Acinetobacter/inmunología , Acinetobacter baumannii/inmunología , Animales , Antibacterianos/uso terapéutico , Humanos

RESUMEN

Respiratory infections caused by multidrug-resistant Acinetobacter baumannii are difficult to treat and associated with high mortality among critically ill hospitalized patients. Bacteriophages (phages) eliminate pathogens with high host specificity and efficacy. However, the lack of appropriate preclinical experimental models hampers the progress of clinical development of phages as therapeutic agents. Therefore, we tested the efficacy of a purified lytic phage, vB_AbaM_Acibel004, against multidrug-resistant A. baumannii clinical isolate RUH 2037 infection in immunocompetent mice and a human lung tissue model. Sham- and A. baumannii-infected mice received a single-dose of phage or buffer via intratracheal aerosolization. Group-specific differences in bacterial burden, immune and clinical responses were compared. Phage-treated mice not only recovered faster from infection-associated hypothermia but also had lower pulmonary bacterial burden, lower lung permeability, and cytokine release. Histopathological examination revealed less inflammation with unaffected inflammatory cellular recruitment. No phage-specific adverse events were noted. Additionally, the bactericidal effect of the purified phage on A. baumannii was confirmed after single-dose treatment in an ex vivo human lung infection model. Taken together, our data suggest that the investigated phage has significant potential to treat multidrug-resistant A. baumannii infections and further support the development of appropriate methods for preclinical evaluation of antibacterial efficacy of phages.

Asunto(s)

Infecciones por Acinetobacter/terapia , Acinetobacter baumannii , Myoviridae/fisiología , Terapia de Fagos , Neumonía Bacteriana/terapia , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/patología , Acinetobacter baumannii/efectos de los fármacos , Acinetobacter baumannii/virología , Animales , Antibacterianos/farmacología , Citocinas/metabolismo , Farmacorresistencia Bacteriana Múltiple , Femenino , Humanos , Pulmón/inmunología , Pulmón/microbiología , Pulmón/patología , Ratones , Ratones Endogámicos C57BL , Terapia de Fagos/efectos adversos , Neumonía Bacteriana/inmunología , Neumonía Bacteriana/microbiología , Neumonía Bacteriana/patología

RESUMEN

Acinetobacter baumannii is an important opportunistic pathogen that primarily afflicts elderly people. To clarify the pathogenicity of A. baumannii in the elderly, we investigated immune responses to A. baumannii ATCC 19606 infection in klotho knockout (KO) mice, the mouse model of aging. Following intravenous inoculation, the mice seldom displayed severe symptoms. However, the survival rate was 56% at 7 days post-infection. Bacteria were detected in the lungs of klotho KO mice but not klotho wildtype (WT) mice at 7 days post-infection. Neutrophils, eosinophils, interstitial macrophages, and monocyte/dendritic cell subset in the lungs of klotho KO mice were transiently induced after infection with A. baumannii. The number of alveolar macrophages in klotho KO mice was lower than that in klotho WT mice, except for 1 day post-infection. CD11b expression on neutrophils and alveolar macrophages in the lungs of klotho KO mice was seldom upregulated by the infection. These results suggested that immune functions eliminating bacteria in the lungs of klotho KO mice were insufficient. CD11blow conventional DC cells hardly increased in klotho KO mice infected with A. baumannii. Additionally, the production of interleukin (IL)-10 in the sera of klotho KO mice was significantly higher than that in klotho WT mice, whereas that production of interferon-gamma was not detected in the sera of klotho KO mice. These results suggested that acquired immune responses were hardly induced in klotho KO mice. IL-1ß, CXCL1, CXCL2, and CCL2 expression was significantly higher in the lungs of klotho KO mice infected with A. baumannii than in those of klotho WT mice at 1 day post-infection. These results suggested that pulmonary inflammation was elicited in klotho KO mice during early infection. The expression levels of proinflammatory cytokines significantly correlated with TLR9 expression in the lungs of klotho KO mice. The collective results demonstrate an A. baumannii infection state in aged hosts and suggest that pulmonary inflammation and bacterial burden should be noted in aged hosts even in the absence of severe symptoms of A. baumannii infection.

Asunto(s)

Infecciones por Acinetobacter/inmunología , Acinetobacter baumannii/inmunología , Citocinas/metabolismo , Glucuronidasa/deficiencia , Pulmón/inmunología , Neumonía Bacteriana/inmunología , Infecciones por Acinetobacter/genética , Infecciones por Acinetobacter/metabolismo , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/patogenicidad , Factores de Edad , Animales , Carga Bacteriana , Citocinas/genética , Modelos Animales de Enfermedad , Glucuronidasa/genética , Interacciones Huésped-Parásitos , Proteínas Klotho , Pulmón/metabolismo , Pulmón/microbiología , Masculino , Ratones Noqueados , Neumonía Bacteriana/genética , Neumonía Bacteriana/metabolismo , Neumonía Bacteriana/microbiología , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/metabolismo

RESUMEN

Acinetobacter baumannii (A. baumannii) is an important opportunistic pathogen widely present in medical environment. Given its complex drug resistance, A. baumannii poses a serious threat to the safety of critically ill patients. Given the limited alternative antibiotics, nonantibiotic-based functional anti-A. baumannii infection proteins must be developed. In this study, we firstly used a series of biological software to predict potential epitopes in the MacB protein sequence and verified them by antibody recognition and lymphocyte proliferation tests. We finally screened out B cell epitope 2, CD8+ T cell epitope 7, and CD4+ T cell epitope 11 and connected them to construct a recombinant antigen epitope (RAE). The determination of IgG in the serum of immunised mice and cytokines in the supernatant of lymphocytes showed that the constructed epitope induced an immune response mediated by Th-1 cells. Finally, the challenge experiment of A. baumannii infection in mice confirmed that the epitope developed based on MacB, especially RAE, provided incomplete immune protection for mice.

Asunto(s)

Transportadoras de Casetes de Unión a ATP/inmunología , Infecciones por Acinetobacter/prevención & control , Acinetobacter baumannii/efectos de los fármacos , Antígenos Bacterianos/inmunología , Proteínas Bacterianas/inmunología , Epítopos de Linfocito B/inmunología , Proteínas Recombinantes de Fusión/administración & dosificación , Transportadoras de Casetes de Unión a ATP/química , Transportadoras de Casetes de Unión a ATP/genética , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/inmunología , Animales , Antígenos Bacterianos/química , Antígenos Bacterianos/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Antígenos CD4/genética , Antígenos CD4/inmunología , Epítopos de Linfocito B/química , Epítopos de Linfocito B/genética , Epítopos de Linfocito T/genética , Epítopos de Linfocito T/inmunología , Femenino , Humanos , Inmunidad Celular/efectos de los fármacos , Inmunogenicidad Vacunal , Ratones , Ratones Endogámicos BALB C , Modelos Moleculares , Proteínas Recombinantes de Fusión/biosíntesis , Proteínas Recombinantes de Fusión/genética , Células TH1/efectos de los fármacos , Células TH1/inmunología , Células TH1/microbiología

RESUMEN

Acinetobacter baumannii is considered one of the most persistent pathogens responsible for nosocomial infections. Due to the emergence of multidrug resistant strains, as well as high morbidity and mortality caused by this pathogen, A. baumannii was placed on the World Health Organization (WHO) drug-resistant bacteria and antimicrobial resistance research priority list. This review summarizes current studies on mechanisms that protect A. baumannii against multiple stresses caused by the host immune response, outside host environment, and antibiotic treatment. We particularly focus on the ability of A. baumannii to survive long-term desiccation on abiotic surfaces and the population heterogeneity in A. baumannii biofilms. Insight into these protective mechanisms may provide clues for the development of new strategies to fight multidrug resistant strains of A. baumannii.

Asunto(s)

Infecciones por Acinetobacter/genética , Acinetobacter baumannii/genética , Interacciones Huésped-Patógeno/genética , Inmunidad/genética , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/microbiología , Acinetobacter baumannii/patogenicidad , Antibacterianos/uso terapéutico , Biopelículas/crecimiento & desarrollo , Farmacorresistencia Bacteriana Múltiple/genética , Humanos , Virulencia/genética

RESUMEN

Acinetobacter baumannii (A. baumannii) is becoming a common global concern due to the emergence of multi-drug or pan-drug resistant strains. Confronting the issue of antimicrobial resistance by developing vaccines against the resistant pathogen is becoming a common strategy. In this study, different methods for preparing A. baumannii outer membrane vesicles (AbOMVs) vaccines were developed. sOMV (spontaneously released AbOMV) was extracted from the culture supernatant, while SuOMV (sucrose-extracted AbOMV) and nOMV (native AbOMV) were prepared from the bacterial cells. Three AbOMVs exhibited significant differences in yield, particle size, protein composition, and LPS/DNA content. To compare the protective efficacy of the three AbOMVs, groups of mice were immunized either intramuscularly or intranasally with each AbOMV. Vaccination via both routes conferred significant protection against lethal and sub-lethal A. baumannii challenge. Moreover, intranasal vaccination provided more robust protection, which may be attributed to the induction of significant sIgA response in mucosal sites. Among the three AbOMVs, SuOMV elicited the highest level of protective immunity against A. baumannii infection, whether intramuscular or intranasal immunization, which was characterized by the expression of the most profound specific serum IgG or mucosal sIgA. Taken together, the preparation method had a significant effect on the yield, morphology, and composition of AbOMVs, that further influenced the protective effect against A. baumannii infection.

Asunto(s)

Acinetobacter baumannii/inmunología , Vacunas Bacterianas/aislamiento & purificación , Infecciones por Acinetobacter/inmunología , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/prevención & control , Acinetobacter baumannii/patogenicidad , Acinetobacter baumannii/ultraestructura , Administración Intranasal , Animales , Anticuerpos Antibacterianos/biosíntesis , Anticuerpos Antibacterianos/sangre , Especificidad de Anticuerpos , Membrana Externa Bacteriana/inmunología , Membrana Externa Bacteriana/ultraestructura , Proteínas de la Membrana Bacteriana Externa/inmunología , Proteínas de la Membrana Bacteriana Externa/aislamiento & purificación , Vacunas Bacterianas/administración & dosificación , Vacunas Bacterianas/inmunología , Citocinas/metabolismo , Células Dendríticas/inmunología , Modelos Animales de Enfermedad , Femenino , Humanos , Inmunidad Mucosa , Inmunoglobulina A Secretora/biosíntesis , Inmunoglobulina G/sangre , Inmunoglobulina G/clasificación , Ratones , Ratones Endogámicos C57BL , Microscopía Electrónica de Transmisión