scholarly journals Novel Odoribacter splanchnicus Strain and Its Outer Membrane Vesicles Exert Immunoregulatory Effects in vitro

2020 ◽  
Vol 11 ◽  
Author(s):  
Kaisa Hiippala ◽  
Gonçalo Barreto ◽  
Claudia Burrello ◽  
Angelica Diaz-Basabe ◽  
Maiju Suutarinen ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles

In vitro study of virulence potential of Acinetobacter baumannii outer membrane vesicles

2017 ◽  
Vol 111 ◽  
pp. 218-224 ◽  
Author(s):  
Chandana Jha ◽  
Sujata Ghosh ◽  
Vikas Gautam ◽  
Pankaj Malhotra ◽  
Pallab Ray
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
In Vitro Study ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Vitro Study ◽  
Virulence Potential

scholarly journals Effect of Borrelia burgdorferi Outer Membrane Vesicles on Host Oxidative Stress Response

Antibiotics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 275
Author(s):  
Keith Wawrzeniak ◽  
Gauri Gaur ◽  
Eva Sapi ◽  
Alireza G. Senejani
Keyword(s):  
Oxidative Stress ◽  
Borrelia Burgdorferi ◽  
Outer Membrane ◽  
Neuroblastoma Cells ◽  
Membrane Vesicles ◽  
Antioxidant Response ◽  
Outer Membrane Vesicles ◽  
Vitro Model ◽  
Superoxide Dismutase 2

Outer membrane vesicles (OMVs) are spherical bodies containing proteins and nucleic acids that are released by Gram-negative bacteria, including Borrelia burgdorferi, the causative agent of Lyme disease. The functional relationship between B. burgdorferi OMVs and host neuron homeostasis is not well understood. The objective of this study was to examine how B. burgdorferi OMVs impact the host cell environment. First, an in vitro model was established by co-culturing human BE2C neuroblastoma cells with B. burgdorferi B31. B. burgdorferi was able to invade BE2C cells within 24 h. Despite internalization, BE2C cell viability and levels of apoptosis remained unchanged, but resulted in dramatically increased production of MCP-1 and MCP-2 cytokines. Elevated secretion of MCP-1 has previously been associated with changes in oxidative stress. BE2C cell mitochondrial superoxides were reduced as early as 30 min after exposure to B. burgdorferi and OMVs. To rule out whether BE2C cell antioxidant response is the cause of decline in superoxides, superoxide dismutase 2 (SOD2) gene expression was assessed. SOD2 expression was reduced upon exposure to B. burgdorferi, suggesting that B. burgdorferi might be responsible for superoxide reduction. These results suggest that B. burgdorferi modulates cell antioxidant defense and immune system reaction in response to the bacterial infection. In summary, these results show that B. burgdorferi OMVs serve to directly counter superoxide production in BE2C neurons, thereby ‘priming’ the host environment to support B. burgdorferi colonization.

scholarly journals Decoration of Outer Membrane Vesicles with Multiple Antigens by Using an Autotransporter Approach

2014 ◽  
Vol 80 (18) ◽  
pp. 5854-5865 ◽  
Author(s):  
Maria H. Daleke-Schermerhorn ◽  
Tristan Felix ◽  
Zora Soprova ◽  
Corinne M. ten Hagen-Jongman ◽  
David Vikström ◽  
...  
Keyword(s):  
Immune Responses ◽  
Outer Membrane ◽  
Vaccine Development ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Heterologous Proteins ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Heterologous Antigens

ABSTRACTOuter membrane vesicles (OMVs) are spherical nanoparticles that naturally shed from Gram-negative bacteria. They are rich in immunostimulatory proteins and lipopolysaccharide but do not replicate, which increases their safety profile and renders them attractive vaccine vectors. By packaging foreign polypeptides in OMVs, specific immune responses can be raised toward heterologous antigens in the context of an intrinsic adjuvant. Antigens exposed at the vesicle surface have been suggested to elicit protection superior to that from antigens concealed inside OMVs, but hitherto robust methods for targeting heterologous proteins to the OMV surface have been lacking. We have exploited our previously developed hemoglobin protease (Hbp) autotransporter platform for display of heterologous polypeptides at the OMV surface. One, two, or three of theMycobacterium tuberculosisantigens ESAT6, Ag85B, and Rv2660c were targeted to the surface ofEscherichia coliOMVs upon fusion to Hbp. Furthermore, a hypervesiculating ΔtolRΔtolAderivative of attenuatedSalmonella entericaserovar Typhimurium SL3261 was generated, enabling efficient release and purification of OMVs decorated with multiple heterologous antigens, exemplified by theM. tuberculosisantigens and epitopes fromChlamydia trachomatismajor outer membrane protein (MOMP). Also, we showed that delivery ofSalmonellaOMVs displaying Ag85B to antigen-presenting cellsin vitroresults in processing and presentation of an epitope that is functionally recognized by Ag85B-specific T cell hybridomas. In conclusion, the Hbp platform mediates efficient display of (multiple) heterologous antigens, individually or combined within one molecule, at the surface of OMVs. Detection of antigen-specific immune responses upon vesicle-mediated delivery demonstrated the potential of our system for vaccine development.

scholarly journals Repression of the Inner Membrane Lipoprotein NlpA by Rns in Enterotoxigenic Escherichia coli

2006 ◽  
Vol 189 (5) ◽  
pp. 1627-1632 ◽  
Author(s):  
Maria D. Bodero ◽  
M. Carolina Pilonieta ◽  
George P. Munson
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Enterotoxigenic Escherichia Coli ◽  
Start Codon ◽  
Inner Membrane ◽  
E Coli ◽  
Inner Membrane Protein

ABSTRACT The expression of the inner membrane protein NlpA is repressed by the enterotoxigenic Escherichia coli (ETEC) virulence regulator Rns, a member of the AraC/XylS family. The Rns homologs CfaD from ETEC and AggR from enteroaggregative E. coli also repress expression of nlpA. In vitro DNase I and potassium permanganate footprinting revealed that Rns binds to a site overlapping the start codon of nlpA, preventing RNA polymerase from forming an open complex at nlpAp. A second Rns binding site between positions −152 and −195 relative to the nlpA transcription start site is not required for repression. NlpA is not essential for growth of E. coli under laboratory conditions, but it does contribute to the biogenesis of outer membrane vesicles. As outer membrane vesicles have been shown to contain ETEC heat-labile toxin, the repression of nlpA may be an indirect mechanism through which the virulence regulators Rns and CfaD limit the release of toxin.

scholarly journals Horizontal Transfer of the OXA-24 Carbapenemase Gene via Outer Membrane Vesicles: a New Mechanism of Dissemination of Carbapenem Resistance Genes in Acinetobacter baumannii

2011 ◽  
Vol 55 (7) ◽  
pp. 3084-3090 ◽  
Author(s):  
Carlos Rumbo ◽  
Esteban Fernández-Moreira ◽  
María Merino ◽  
Margarita Poza ◽  
Jose Antonio Mendez ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Resistance Genes ◽  
Carbapenem Resistance ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Content Type ◽  
Class D ◽  
Carbapenemase Gene

ABSTRACTThe resistance ofAcinetobacter baumanniistrains to carbapenems is a worrying problem in hospital settings. The main mechanism of carbapenem resistance is the expression of β-lactamases (metalloenzymes or class D enzymes). The mechanisms of the dissemination of these genes amongA. baumanniistrains are not fully understood. In this study we used two carbapenem-resistant clinical strains ofA. baumannii(AbH12O-A2 and AbH12O-CU3) expressing the plasmid-borneblaOXA-24gene (plasmids pMMA2 and pMMCU3, respectively) to demonstrate thatA. baumanniireleases outer membrane vesicles (OMVs) duringin vitrogrowth. The use of hybridization studies enabled us to show that these OMVs harbored theblaOXA-24gene. The incubation of these OMVs with the carbapenem-susceptibleA. baumanniiATCC 17978 host strain yielded full resistance to carbapenems. The presence of the original plasmids harboring theblaOXA-24gene was detected in strain ATCC 17978 after the transformation of OMVs. New OMVs harboringblaOXA-24were released byA. baumanniiATCC 17978 after it was transformed with the original OMV-mediated plasmids, indicating the universality of the process. We present the first experimental evidence that clinical isolates ofA. baumanniimay release OMVs as a mechanism of horizontal gene transfer whereby carbapenem resistance genes are delivered to surroundingA. baumanniibacterial isolates.

An Investigation into the Effects of Outer Membrane Vesicles and Lipopolysaccharide of Porphyromonas gingivalis on Blood-Brain Barrier Integrity, Permeability, and Disruption of Scaffolding Proteins in a Human in vitro Model

2022 ◽  
pp. 1-22
Author(s):  
Anna Barlach Pritchard ◽  
Zsolt Fabian ◽  
Clare L. Lawrence ◽  
Glyn Morton ◽  
StJohn Crean ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Human Brain ◽  
Outer Membrane ◽  
Porphyromonas Gingivalis ◽  
Virulence Factors ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Microvascular Endothelial Cells ◽  
Brain Microvascular Endothelial Cells

Background: The effects of the key pathogens and virulence factors associated with gum disease such as Porphyromonas gingivalis (P. gingivalis) on the central nervous system is of great interest with respect to development of neuropathologies and hence therapeutics and preventative strategies. Chronic infections and associated inflammation are known to weaken the first line of defense for the brain, the blood-brain barrier (BBB). Objective: The focus of this study is to utilize an established human in vitro BBB model to evaluate the effects of P. gingivalis virulence factors lipopolysaccharide (LPS) and outer membrane vesicles (OMVs) on a primary-derived human model representing the neurovascular unit of the BBB. Methods: Changes to the integrity of the BBB after application of P. gingivalis LPS and OMVs were investigated and correlated with transport of LPS. Additionally, the effect of P. gingivalis LPS and OMVs on human brain microvascular endothelial cells in monolayer was evaluated using immunofluorescence microscopy. Results: The integrity of the BBB model was weakened by application of P. gingivalis LPS and OMVs, as measured by a decrease in electrical resistance and a recovery deficit was seen in comparison to the controls. Application of P. gingivalis OMVs to a monoculture of human brain microvascular endothelial cells showed disruption of the tight junction zona occludens protein (ZO-1) compared to controls. Conclusion: These findings show that the integrity of tight junctions of the human BBB could be weakened by association with P. gingivalis virulence factors LPS and OMVs containing proteolytic enzymes (gingipains).

scholarly journals Outer membrane vesicles catabolize lignin-derived aromatic compounds in Pseudomonas putida KT2440

2020 ◽  
Vol 117 (17) ◽  
pp. 9302-9310 ◽  
Author(s):  
Davinia Salvachúa ◽  
Allison Z. Werner ◽  
Isabel Pardo ◽  
Martyna Michalska ◽  
Brenna A. Black ◽  
...  
Keyword(s):  
Pseudomonas Putida ◽  
Outer Membrane ◽  
Aromatic Compounds ◽  
Value Added ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Pseudomonas Putida Kt2440 ◽  
Rich Media

Lignin is an abundant and recalcitrant component of plant cell walls. While lignin degradation in nature is typically attributed to fungi, growing evidence suggests that bacteria also catabolize this complex biopolymer. However, the spatiotemporal mechanisms for lignin catabolism remain unclear. Improved understanding of this biological process would aid in our collective knowledge of both carbon cycling and microbial strategies to valorize lignin to value-added compounds. Here, we examine lignin modifications and the exoproteome of three aromatic–catabolic bacteria: Pseudomonas putida KT2440, Rhodoccocus jostii RHA1, and Amycolatopsis sp. ATCC 39116. P. putida cultivation in lignin-rich media is characterized by an abundant exoproteome that is dynamically and selectively packaged into outer membrane vesicles (OMVs). Interestingly, many enzymes known to exhibit activity toward lignin-derived aromatic compounds are enriched in OMVs from early to late stationary phase, corresponding to the shift from bioavailable carbon to oligomeric lignin as a carbon source. In vivo and in vitro experiments demonstrate that enzymes contained in the OMVs are active and catabolize aromatic compounds. Taken together, this work supports OMV-mediated catabolism of lignin-derived aromatic compounds as an extracellular strategy for nutrient acquisition by soil bacteria and suggests that OMVs could potentially be useful tools for synthetic biology and biotechnological applications.

scholarly journals Immune responses of meningococcal B outer membrane vesicles in middle-aged mice

2020 ◽  
Vol 78 (5) ◽  
Author(s):  
Gabriela Trzewikoswki de Lima ◽  
Thais Sousa Rodrigues ◽  
Amanda Izeli Portilho ◽  
Victor Araujo Correa ◽  
Emanuelle Baldo Gaspar ◽  
...  
Keyword(s):  
Immune Response ◽  
Outer Membrane ◽  
Membrane Vesicles ◽  
The Elderly ◽  
Outer Membrane Vesicles ◽  
Control Group ◽  
Middle Aged ◽  
Aged Mice ◽  
Robust Immune Response

ABSTRACT The elderly are more likely to die when infected with Neisseria meningitidis. Aging is associated with immune system dysfunctions that impair responses to vaccines and infections. Therefore, immunization of middle-aged individuals could be beneficial. This study aims to evaluate the immunogenicity of N. meningitidis B outer membrane vesicles (OMVs) complexed to two different adjuvants. Middle-aged BALB/c and A/Sn mice were immunized and subsequent immune response was assessed by ELISA, immunoblotting and ELISpot. IgG levels were similar between the animals immunized with OMVs complexed to adjuvants. A total of 235 days after the last immunization only A/Sn mice presented higher IgG levels than those observed in the baseline, especially the group immunized with OMVs and aluminum hydroxide. The predominant IgG subclasses were IgG2a and IgG2b. Immunization with the three-dose regimen generated IgG antibodies that recognized a variety of antigens present in the homologous and heterologous meningococcal OMVs evaluated. There was an increase in the frequency of antigen-specific IFN-γ secreting splenocytes, after in vitro stimulation, in mice immunized with OMVs and adjuvants compared to the control group, almost 1 year after the last immunization. Both adjuvants showed similar performance. Immunization of middle-aged mice has generated a robust immune response and it appears to be advantageous.

scholarly journals Mucosal Immunization with Vibrio cholerae Outer Membrane Vesicles Provides Maternal Protection Mediated by Antilipopolysaccharide Antibodies That Inhibit Bacterial Motility

2010 ◽  
Vol 78 (10) ◽  
pp. 4402-4420 ◽  
Author(s):  
Anne L. Bishop ◽  
Stefan Schild ◽  
Bharathi Patimalla ◽  
Brian Klein ◽  
Andrew Camilli
Keyword(s):  
Outer Membrane ◽  
Vibrio Cholerae ◽  
Diarrheal Disease ◽  
Protective Antigen ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Clean Water ◽  
Mucosal Immunization ◽  
Maternal Protection

ABSTRACTVibrio choleraeis the causative agent of cholera, a severe diarrheal disease that remains endemic in many parts of the world and can cause outbreaks wherever sanitation and clean water systems break down. Prevention of disease could be achieved through improved sanitation and clean water provision supported by vaccination.V. choleraeserogroup O1 is the major cause of cholera; O1 serotypes Inaba and Ogawa have similar disease burdens, while O139 is the only non-O1 serogroup to cause epidemics. We showed previously that immunization of adult female mice with purifiedV. choleraeouter membrane vesicles (OMVs) elicits an antibody response that protect neonates from oralV. choleraechallenge and that suckling from an immunized dam accounts for the majority of protection fromV. choleraecolonization. Here we report that lipopolysaccharide (LPS) is the major OMV protective antigen. Mucosal immunization with OMVs from Inaba or Ogawa provides significant cross-serotype protection fromV. choleraecolonization, although serotype-specific antigens are dominant. OMVs from O1 or O139 do not provide cross-serogroup protection, but by immunization with a mixture of O1 and O139 OMVs, cross-serogroup protection was achieved. Neonatal protection is not associated with significant bacterial death but may involve inhibition of motility, as antibodies from OMV-immunized mice inhibitV. choleraemotilityin vitro, with trends that parallelin vivoprotection. Motility assays also reveal that a higher antibody titer is required to immobilize O139 compared to O1, a phenotype that is O139 capsule dependent.

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