Bacterial outer membrane vesicles: New insights and applications

Anand, Deepak; Chaudhuri, Arunima

doi:10.1080/09687688.2017.1400602

Cited by 50 publications

(46 citation statements)

References 118 publications

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“…The strength of lipopolysaccharide bilayers can evidently be modulated through LPS capping/Oantigen expression, providing a simple method to control the durability of outer membrane vesicles, which are increasingly being used as vaccine adjuvants and are garnering attention for their potential nanomedicinal applications. [54][55][56] Modulating the mechanical strength of comparable glycerophospholipid nanocarriers through the incorporation of amphiphilic block copolymers was shown to not only enhance their shelf stability but also to reduce their toxicity, and increase the loading rates of drugs and drug cellular uptake. [57][58][59] Going forward, the use of alternative simulation methods that can…”

Section: Resultsmentioning

confidence: 99%

Role of O-Antigen in Response to Mechanical Stress of the E. coli Outer Membrane: Insights from Coarse-Grained MD Simulations

2019

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Lipopolysaccharide (LPS) is an important component of the outer membrane of Gram-negative bacteria, contributing to the structural integrity of the bacterial cell wall and conferring resistance to chemical attack. The rough variant of LPS contains a conserved lipid A domain and complete core saccharide section, while the smooth variant additionally contains a terminal O-antigen chain. In the following, smooth LPS lipids are simulated in multicomponent membrane models using coarse-grained molecular dynamics. The simulations reveal that the lipid environment of smooth LPS lipids affects the orientation and clustering of their O-antigen chains. When the outer membrane leaflets contain smooth LPS lipids alone the O-antigen chains are packed tightly, leading to strong cohesive intermolecular interactions. When the outer leaflets incorporate interstitial phospholipids and rough LPS variants, the O-antigen chains are tilted and less tightly bound. The different packing of terminal O-antigen chains affects lipid mobility and the mechanical strength of the Gram-negative membrane models. Gram-negative membranes with outer leaflets of smooth LPS alone can withstand surface tensions (150 mNm-1) that cause the membrane models with rough LPS lipids and comparable phospholipid bilayers to rupture much more readily.

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Section: Resultsmentioning

confidence: 99%

Role of O-Antigen in Response to Mechanical Stress of the E. coli Outer Membrane: Insights from Coarse-Grained MD Simulations

2019

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“…Moreover, LPS and other bacterial antigens may exert profound neurotoxic effects [28] by accessing the brain via different routes, including the blood-brain-barrier, the circumventricular organs and area postrema, or via outer membrane vesicles [28][29][30][31][32][33]. Based on this knowledge, we concluded that schizophrenia patients with lowered natural IgM are more prone to the detrimental effects of LPS and other bacterial neurotoxic antigens, which in turn may drive schizophrenia symptoms including memory impairments [25].…”

Section: Introductionmentioning

confidence: 99%

Upregulation of the Intestinal Paracellular Pathway with Breakdown of Tight and Adherens Junctions in Deficit Schizophrenia

Maes¹,

Sirivichayakul²,

Kanchanatawan³

et al. 2019

Preprint

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In 2001, the first author of this paper reported that schizophrenia is associated with an increased frequency of the haptoglobin (Hp)-2 gene. The precursor of Hp-2 is zonulin, a molecule that affects intercellular tight junction integrity. Recently, we reported increased plasma IgA/IgM responses to Gram-negative bacteria in deficit schizophrenia indicating leaky gut and gut dysbiosis. The current study was performed to examine the integrity of the paracellular (tight and adherens junctions) and transcellular (cytoskeletal proteins) pathways in deficit versus non-deficit schizophrenia. We measured IgM responses to zonulin, occludin, E-cadherin, talin, actin and vinculin in association with IgA responses to Gram-negative bacteria, CCL-11, IgA responses to tryptophan catabolites (TRYCATs), immune activation and IgM to malondialdehyde (MDA) and NO-cysteinyl in 78 schizophrenia patients and 40 controls. We found that the ratio of IgM to zonulin + occudin / talin + actin + viculin (PARA/TRANS) was significantly greater in deficit than in non-deficit schizophrenia and higher in schizophrenia than controls and was significantly associated with increased IgA responses to Gram-negative bacteria. IgM responses to zonulin were positively associated with schizophrenia (versus controls), while IgM to occludin was significantly associated with deficit schizophrenia (versus non-deficit schizophrenia and controls). A large part of the variance (90.8%) in negative and PHEM (psychosis, hostility, excitation and mannerism) symptoms was explained by PARA/TRANS ratio, IgA to Gram-negative bacteria, IgM to E-cadherin and malondialdehyde (MDA) and memory dysfunctions, while 53.3% of the variance in the latter was explained by PARA/TRANS ratio, IgA to Gram-negative bacteria, CCL-11, TRYCATs and immune activation. The results show an upregulated paracellular pathway with breakdown of the tight and ahherens junctions and increased bacterial translocation in deficit schizophrenia. These dysfunctions in the intestinal paracellular route together with lowered natural IgM, immune activation and production of CCL-11 and TRYCATs contribute to the phenomenology of deficit schizophrenia.

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“…It is likely that the observed surface structures on cells of strain LFY10 were membrane vesicles (MVs). The production of MVs is widespread among microorganisms, discovered first in Gram-negative bacteria and since identified in species from all three domains of life (Deatherage and Cookson, 2012; Anand and Chaudhuri, 2016). Pseudomonas fluorescens , a close relative to strain LFY10, produces MVs that are formed when the outer membrane of the cell wall bulges outward, fills with periplasm, and then pinches off to form a spherical vesicle (Guyard-Nicodème et al, 2007; Anand and Chaudhuri, 2016), a process that is consistent with our observations of strain LFY10.…”

Section: Discussionmentioning

confidence: 99%

Chemoorganotrophic Bacteria From Lake Fryxell, Antarctica, Including Pseudomonas Strain LFY10, a Cold-Adapted, Halotolerant Bacterium Useful in Teaching Labs

Baker¹,

Schaaf²,

Cunningham³

et al. 2019

Front. Microbiol.

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Lake Fryxell, situated in the McMurdo Dry Valleys of Antarctica, is an intriguing aquatic ecosystem because of its perennial ice cover, highly stratified water column, and extreme physicochemical conditions, which collectively restrict lake biodiversity to solely microbial forms. To expand our current understanding of the cultivable biodiversity of Lake Fryxell, water samples were collected from depths of 10 and 17 m, and pure cultures of eight diverse strains of aerobic, chemoorganotrophic bacteria were obtained. Despite having high 16S rRNA gene sequence similarity to mesophilic bacteria inhabiting various temperate environments, all Lake Fryxell isolates were psychrotolerant, with growth occurring at 0°C and optimal growth from 18–24°C for all isolates. Phylogenetic analyses showed the isolates to be members of six taxonomic groups, including the genera Brevundimonas, Arthrobacter, Sphingobium, Leifsonia, and Pseudomonas, as well as the family Microbacteriaceae (one strain could not reliably be assigned to a specific genus based on our analysis). Pseudomonas strain LFY10 stood out as a useful tool for teaching laboratory activities because of its substantial cold adaptation (visible growth is evident in 1–2 days at 4°C), beta-hemolytic activity, and halotolerance to 8.5% (w/v) NaCl. These cold-adapted bacteria likely play a role in carbon mineralization and other nutrient cycling in Lake Fryxell, and their characterization broadens our understanding of microbial biodiversity in aquatic polar ecosystems.

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Bacterial outer membrane vesicles: New insights and applications

Cited by 50 publications

References 118 publications

Role of O-Antigen in Response to Mechanical Stress of the E. coli Outer Membrane: Insights from Coarse-Grained MD Simulations

Role of O-Antigen in Response to Mechanical Stress of the E. coli Outer Membrane: Insights from Coarse-Grained MD Simulations

Upregulation of the Intestinal Paracellular Pathway with Breakdown of Tight and Adherens Junctions in Deficit Schizophrenia

Chemoorganotrophic Bacteria From Lake Fryxell, Antarctica, Including Pseudomonas Strain LFY10, a Cold-Adapted, Halotolerant Bacterium Useful in Teaching Labs

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