scholarly journals NOD-Like Receptor Activation by Outer Membrane Vesicles fromVibrio choleraeNon-O1 Non-O139 Strains Is Modulated by the Quorum-Sensing Regulator HapR

2011 ◽  
Vol 79 (4) ◽  
pp. 1418-1427 ◽  
Author(s):  
H. Bielig ◽  
P. K. Rompikuntal ◽  
M. Dongre ◽  
B. Zurek ◽  
B. Lindmark ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Immune Responses ◽  
Outer Membrane ◽  
Inflammatory Responses ◽  
Membrane Vesicles ◽  
Receptor Activation ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Mammalian Host ◽  
Host Immune Responses

ABSTRACTVibrio choleraeis an inhabitant of aquatic systems and one of the causative agents of severe dehydrating diarrhea in humans. It has also emerged as an important cause of different kinds of inflammatory responses, and in particular,V. choleraestrains of the non-O1 non-O139 serogroups (NOVC) have been associated with such infections in human. We analyzed the potential of outer membrane vesicles (OMVs) derived from the NOVC strain V:5/04 to induce inflammatory responses in human host cells. V:5/04 OMVs were taken up by human epithelial cells and induced inflammatory responses. Small interfering RNA (siRNA)-mediated gene knockdown revealed that the inflammatory potential of NOVC OMVs was partially mediated by the nucleotide-binding domain-, leucine-rich repeat-containing family member NOD1. Physiochemical analysis of the content of these OMVs, in conjunction with NOD1 and NOD2 reporter assays in HEK293T cells, confirmed the presence of both NOD1 and NOD2 active peptidoglycan in the OMVs. Furthermore, we show that deletion of the quorum-sensing regulator HapR, which mimics an infective life style, specifically reduced the inflammatory potential of the V:5/04 OMVs and their ability to activate NOD1 and NOD2. In conclusion, our study shows that NOVC OMVs elicit immune responses mediated by NOD1 and NOD2 in mammalian host cells. Moreover, we provide evidence that the quorum-sensing machinery plays an important regulatory role in this process by attenuating the inflammatory potential of OMVs under infective conditions. This work thus identifies a new facet of howVibrioaffects host immune responses and defines a role for the quorum-sensing machinery in this process.

scholarly journals Aggregatibacter actinomycetemcomitans Outer Membrane Vesicles Are Internalized in Human Host Cells and Trigger NOD1- and NOD2-Dependent NF-κB Activation

2014 ◽  
Vol 82 (10) ◽  
pp. 4034-4046 ◽  
Author(s):  
Bernard Thay ◽  
Anna Damm ◽  
Thomas A. Kufer ◽  
Sun Nyunt Wai ◽  
Jan Oscarsson
Keyword(s):  
Outer Membrane ◽  
Hela Cells ◽  
Inflammatory Responses ◽  
Membrane Vesicles ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Outer Membrane Vesicles ◽  
Biologically Active ◽  
Host Cells ◽  
Content Type ◽  
Human Embryonic Kidney Cells

ABSTRACTAggregatibacter actinomycetemcomitansis an oral and systemic pathogen associated with aggressive forms of periodontitis and with endocarditis. We recently demonstrated that outer membrane vesicles (OMVs) disseminated byA. actinomycetemcomitanscould deliver multiple proteins, including biologically active cytolethal distending toxin (CDT), into the cytosol of HeLa cells and human gingival fibroblasts (HGF). In the present work, we have used immunoelectron and confocal microscopy analysis and fluorescently labeled vesicles to further investigate mechanisms forA. actinomycetemcomitansOMV-mediated delivery of bacterial antigens to these host cells. Our results supported that OMVs were internalized into the perinuclear region of HeLa cells and HGF. Colocalization analysis revealed that internalized OMVs colocalized with the endoplasmic reticulum and carried antigens, detected using an antibody specific to wholeA. actinomycetemcomitansserotype a cells. Consistent with OMV internalization mediating intracellular antigen exposure, the vesicles acted as strong inducers of cytoplasmic peptidoglycan sensor NOD1- and NOD2-dependent NF-κB activation in human embryonic kidney cells. Moreover, NOD1 was the main sensor of OMV-delivered peptidoglycan in myeloid THP1 cells, contributing to the overall inflammatory responses induced by the vesicles. This work reveals a role ofA. actinomycetemcomitansOMVs as a trigger of innate immunity via carriage of NOD1- and NOD2-active pathogen-associated molecular patterns (PAMPs).

scholarly journals Helicobacter pylori Outer Membrane Vesicles and Extracellular Vesicles from Helicobacter pylori-Infected Cells in Gastric Disease Development

2021 ◽  
Vol 22 (9) ◽  
pp. 4823
Author(s):  
María Fernanda González ◽  
Paula Díaz ◽  
Alejandra Sandoval-Bórquez ◽  
Daniela Herrera ◽  
Andrew F. G. Quest
Keyword(s):  
Gastric Cancer ◽  
Helicobacter Pylori ◽  
Outer Membrane ◽  
Extracellular Vesicles ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Gastric Epithelium ◽  
Infected Cells ◽  
H Pylori

Extracellular vesicles (EVs) are cell-derived vesicles important in intercellular communication that play an essential role in host-pathogen interactions, spreading pathogen-derived as well as host-derived molecules during infection. Pathogens can induce changes in the composition of EVs derived from the infected cells and use them to manipulate their microenvironment and, for instance, modulate innate and adaptive inflammatory immune responses, both in a stimulatory or suppressive manner. Gastric cancer is one of the leading causes of cancer-related deaths worldwide and infection with Helicobacter pylori (H. pylori) is considered the main risk factor for developing this disease, which is characterized by a strong inflammatory component. EVs released by host cells infected with H. pylori contribute significantly to inflammation, and in doing so promote the development of disease. Additionally, H. pylori liberates vesicles, called outer membrane vesicles (H. pylori-OMVs), which contribute to atrophia and cell transformation in the gastric epithelium. In this review, the participation of both EVs from cells infected with H. pylori and H. pylori-OMVs associated with the development of gastric cancer will be discussed. By deciphering which functions of these external vesicles during H. pylori infection benefit the host or the pathogen, novel treatment strategies may become available to prevent disease.

scholarly journals Aggregatibacter actinomycetemcomitans Leukotoxin Is Delivered to Host Cells in an LFA-1-Indepdendent Manner When Associated with Outer Membrane Vesicles

Toxins ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 414 ◽  
Author(s):  
Justin Nice ◽  
Nataliya Balashova ◽  
Scott Kachlany ◽  
Evan Koufos ◽  
Eric Krueger ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Membrane Vesicles ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Aggressive Periodontitis ◽  
Outer Membrane Vesicles ◽  
Host Cells ◽  
Type I ◽  
Outer Membranes ◽  
Independent Mechanism ◽  
Bacterial Outer Membrane

The Gram-negative bacterium, Aggregatibacter actinomycetemcomitans, has been associated with localized aggressive periodontitis (LAP). In particular, highly leukotoxic strains of A. actinomycetemcomitans have been more closely associated with this disease, suggesting that LtxA is a key virulence factor for A. actinomycetemcomitans. LtxA is secreted across both the inner and outer membranes via the Type I secretion system, but has also been found to be enriched within outer membrane vesicles (OMVs), derived from the bacterial outer membrane. We have characterized the association of LtxA with OMVs produced by the highly leukotoxic strain, JP2, and investigated the interaction of these OMVs with host cells to understand how LtxA is delivered to host cells in this OMV-associated form. Our results demonstrated that a significant fraction of the secreted LtxA exists in an OMV-associated form. Furthermore, we have discovered that in this OMV-associated form, the toxin is trafficked to host cells by a cholesterol- and receptor-independent mechanism in contrast to the mechanism by which free LtxA is delivered. Because OMV-associated toxin is trafficked to host cells in an entirely different manner than free toxin, this study highlights the importance of studying both free and OMV-associated forms of LtxA to understand A. actinomycetemcomitans virulence.

scholarly journals Proteomic Characterization of the Whole Secretome of Legionella pneumophila and Functional Analysis of Outer Membrane Vesicles

2008 ◽  
Vol 76 (5) ◽  
pp. 1825-1836 ◽  
Author(s):  
Frank Galka ◽  
Sun Nyunt Wai ◽  
Harald Kusch ◽  
Susanne Engelmann ◽  
Michael Hecker ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Legionella Pneumophila ◽  
Protein Identification ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Laser Scanning Microscopy ◽  
Host Cells ◽  
Confocal Laser ◽  
Lipolytic Enzyme ◽  
New Findings

ABSTRACT Secretion of effector molecules is one of the major mechanisms by which the intracellular human pathogen Legionella pneumophila interacts with host cells during infection. Specific secretion machineries which are responsible for the subfraction of secreted proteins (soluble supernatant proteins [SSPs]) and the production of bacterial outer membrane vesicles (OMVs) both contribute to the protein composition of the extracellular milieu of this lung pathogen. Here we present comprehensive proteome reference maps for both SSPs and OMVs. Protein identification and assignment analyses revealed a total of 181 supernatant proteins, 107 of which were specific to the SSP fraction and 33 of which were specific to OMVs. A functional classification showed that a large proportion of the identified OMV proteins are involved in the pathogenesis of Legionnaires' disease. Zymography and enzyme assays demonstrated that the SSP and OMV fractions possess proteolytic and lipolytic enzyme activities which may contribute to the destruction of the alveolar lining during infection. Furthermore, it was shown that OMVs do not kill host cells but specifically modulate their cytokine response. Binding of immunofluorescently stained OMVs to alveolar epithelial cells, as visualized by confocal laser scanning microscopy, suggested that there is delivery of a large and complex group of proteins and lipids in the infected tissue in association with OMVs. On the basis of these new findings, we discuss the relevance of protein sorting and compartmentalization of virulence factors, as well as environmental aspects of the vesicle-mediated secretion.

scholarly journals Cholera Toxin Encapsulated within Several Vibrio cholerae O1 Serotype Inaba Outer Membrane Vesicles Lacks a Functional B-Subunit

Toxins ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 207 ◽  
Author(s):  
Elnaz Rasti ◽  
Angela Brown
Keyword(s):  
Outer Membrane ◽  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Biologically Active ◽  
Host Cells ◽  
Free Form ◽  
Type Ii Secretion ◽  
Secondary Mechanism

Cholera toxin (CT), the major virulence factor of Vibrio cholerae, is an AB5 toxin secreted through the type II secretion system (T2SS). Upon secretion, the toxin initiates endocytosis through the interaction of the B pentamer with the GM1 ganglioside receptor on small intestinal cells. In addition to the release of CT in the free form, the bacteria secrete CT in association with outer membrane vesicles (OMVs). Previously, we demonstrated that strain 569B releases OMVs that encapsulate CT and which interact with host cells in a GM1-independent mechanism. Here, we have demonstrated that OMV-encapsulated CT, while biologically active, does not exist in an AB5 form; rather, the OMVs encapsulate two enzymatic A-subunit (CTA) polypeptides. We further investigated the assembly and secretion of the periplasmic CT and found that a major fraction of periplasmic CTA does not participate in the CT assembly process and instead is continuously encapsulated within the OMVs. Additionally, we found that the encapsulation of CTA fragments in OMVs is conserved among several Inaba O1 strains. We further found that under conditions in which the amount of extracellularly secreted CT increases, the concentration of OMV-encapsulated likewise CTA increases. These results point to a secondary mechanism for the secretion of biologically active CT that does not depend on the CTB-GM1 interaction for endocytosis.

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 Staphylococcus aureus secretes immunomodulatory RNA and DNA via membrane vesicles

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Blanca V. Rodriguez ◽  
Meta J. Kuehn
Keyword(s):  
Staphylococcus Aureus ◽  
Nucleic Acids ◽  
Immune Modulation ◽  
Membrane Vesicle ◽  
Membrane Vesicles ◽  
Receptor Activation ◽  
Host Cells ◽  
Downstream Signaling ◽  
Host Immune Responses ◽  
Rna And Dna

Abstract Bacterial-derived RNA and DNA can function as ligands for intracellular receptor activation and induce downstream signaling to modulate the host response to bacterial infection. The mechanisms underlying the secretion of immunomodulatory RNA and DNA by pathogens such as Staphylococcus aureus and their delivery to intracellular host cell receptors are not well understood. Recently, extracellular membrane vesicle (MV) production has been proposed as a general secretion mechanism that could facilitate the delivery of functional bacterial nucleic acids into host cells. S. aureus produce membrane-bound, spherical, nano-sized, MVs packaged with a select array of bioactive macromolecules and they have been shown to play important roles in bacterial virulence and in immune modulation through the transmission of biologic signals to host cells. Here we show that S. aureus secretes RNA and DNA molecules that are mostly protected from degradation by their association with MVs. Importantly, we demonstrate that MVs can be delivered into cultured macrophage cells and subsequently stimulate a potent IFN-β response in recipient cells via activation of endosomal Toll-like receptors. These findings advance our understanding of the mechanisms by which bacterial nucleic acids traffic extracellularly to trigger the modulation of host immune responses.

Sign in / Sign up

Export Citation Format

Share Document