scholarly journals Shigella sonneiinfection of zebrafish reveals that O-antigen mediates neutrophil tolerance and dysentery incidence

2019 ◽  
Author(s):  
Vincenzo Torraca ◽  
Myrsini Kaforou ◽  
Jayne Watson ◽  
Gina M. Duggan ◽  
Hazel Guerrero-Gutierrez ◽  
...  
Keyword(s):  
Developing Countries ◽  
Bacillary Dysentery ◽  
Shigella Flexneri ◽  
Shigella Sonnei ◽  
Innate Immune ◽  
Sublethal Dose ◽  
Human Neutrophils ◽  
Dependent Manner ◽  
O Antigen

AbstractShigella flexneriis historically regarded as the primary agent of bacillary dysentery, yet the closely-relatedShigella sonneiis replacingS. flexneri, especially in developing countries. The underlying reasons for this dramatic shift are mostly unknown. Using a zebrafish (Danio rerio) model ofShigellainfection, we discover thatS. sonneiis more virulent thanS. flexneri in vivo. Whole animal dual-RNAseq and testing of bacterial mutants suggest thatS. sonneivirulence depends on its O-antigen oligosaccharide (which is unique amongShigellaspecies). We showin vivousing zebrafish andex vivousing human neutrophils thatS. sonneiO-antigen can mediate neutrophil tolerance. Consistent with this, we demonstrate that O-antigen enablesS. sonneito resist phagolysosome acidification and promotes neutrophil cell death. Chemical inhibition or promotion of phagolysosome maturation respectively decreases and increases neutrophil control ofS. sonneiand zebrafish survival. Strikingly, larvae primed with a sublethal dose ofS. sonneiare protected against a secondary lethal dose ofS. sonneiin an O-antigen-dependent manner, indicating that exposure to O-antigen can train the innate immune system againstS. sonnei. Collectively, these findings reveal O-antigen as an important therapeutic target against bacillary dysentery, and may explain the rapidly increasingS. sonneiburden in developing countries.Author SummaryShigella sonneiis predominantly responsible for dysentery in developed countries, and is replacingShigella flexneriin areas undergoing economic development and improvements in water quality. UsingShigellainfection of zebrafish (in vivo) and human neutrophils (in vitro), we discover thatS. sonneiis more virulent thanS. flexneribecause of neutrophil tolerance mediated by its O-antigen oligosaccharide acquired from the environmental bacteriaPlesiomonas shigelloides. To inspire new approaches forS. sonneicontrol, we show that increased phagolysosomal acidification or innate immune training can promoteS. sonneiclearance by neutrophilsin vivo. These findings have major implications for our evolutionary understanding ofShigella, and may explain why exposure toP. shigelloidesin low and middle-income countries (LMICs) can protect against dysentery incidence.

scholarly journals Neutrophils: back in the thrombosis spotlight

Blood ◽  
2019 ◽  
Vol 133 (20) ◽  
pp. 2186-2197 ◽  
Author(s):  
Denis F. Noubouossie ◽  
Brandi N. Reeves ◽  
Brian D. Strahl ◽  
Nigel S. Key
Keyword(s):  
Animal Models ◽  
Tissue Factor ◽  
Contact System ◽  
Neutrophil Extracellular Trap ◽  
Human Neutrophils ◽  
Dependent Manner ◽  
Extrinsic Pathway ◽  
Vessel Occlusion ◽  
Activated Neutrophils

Abstract Reactive and clonal neutrophil expansion has been associated with thrombosis, suggesting that neutrophils play a role in this process. However, although there is no doubt that activated monocytes trigger coagulation in a tissue factor-dependent manner, it remains uncertain whether stimulated neutrophils can also directly activate coagulation. After more than a decade of debate, it is now largely accepted that normal human neutrophils do not synthetize tissue factor, the initiator of the extrinsic pathway of coagulation. However, neutrophils may passively acquire tissue factor from monocytes. Recently, the contact system, which initiates coagulation via the intrinsic pathway, has been implicated in the pathogenesis of thrombosis. After the recent description of neutrophil extracellular trap (NET) release by activated neutrophils, some animal models of thrombosis have demonstrated that coagulation may be enhanced by direct NET-dependent activation of the contact system. However, there is currently no consensus on how to assess or quantify NETosis in vivo, and other experimental animal models have failed to demonstrate a role for neutrophils in thrombogenesis. Nevertheless, it is likely that NETs can serve to localize other circulating coagulation components and can also promote vessel occlusion independent of fibrin formation. This article provides a critical appraisal of the possible roles of neutrophils in thrombosis and highlights some existing knowledge gaps regarding the procoagulant activities of neutrophil-derived extracellular chromatin and its molecular components. A better understanding of these mechanisms could guide future approaches to prevent and/or treat thrombosis.

scholarly journals Redundant Catalases Detoxify Phagocyte Reactive Oxygen and Facilitate Histoplasma capsulatum Pathogenesis

2013 ◽  
Vol 81 (7) ◽  
pp. 2334-2346 ◽  
Author(s):  
Eric D. Holbrook ◽  
Katherine A. Smolnycki ◽  
Brian H. Youseff ◽  
Chad A. Rappleye
Keyword(s):  
Immune System ◽  
Innate Immune System ◽  
Histoplasma Capsulatum ◽  
Reactive Oxygen ◽  
Innate Immune ◽  
Respiratory Pathogen ◽  
Human Neutrophils ◽  
Content Type

ABSTRACTHistoplasma capsulatumis a respiratory pathogen that infects phagocytic cells. The mechanisms allowingHistoplasmato overcome toxic reactive oxygen molecules produced by the innate immune system are an integral part ofHistoplasma's ability to survive during infection. To probe the contribution ofHistoplasmacatalases in oxidative stress defense, we created and analyzed the virulence defects of mutants lacking CatB and CatP, which are responsible for extracellular and intracellular catalase activities, respectively. Both CatB and CatP protectedHistoplasmafrom peroxide challengein vitroand from antimicrobial reactive oxygen produced by human neutrophils and activated macrophages. Optimal protection required both catalases, as the survival of a double mutant lacking both CatB and CatP was lower than that of single-catalase-deficient cells. Although CatB contributed to reactive oxygen species defensesin vitro, CatB was dispensable for lung infection and extrapulmonary disseminationin vivo. Loss of CatB from a strain also lacking superoxide dismutase (Sod3) did not further reduce the survival ofHistoplasmayeasts. Nevertheless, some catalase function was required for pathogenesis since simultaneous loss of both CatB and CatP attenuatedHistoplasmavirulencein vivo. These results demonstrate thatHistoplasma's dual catalases comprise a system that enablesHistoplasmato efficiently overcome the reactive oxygen produced by the innate immune system.

scholarly journals Use of Bacteriophage Ba1 To Identify Properties Associated with Bordetella avium Virulence

2002 ◽  
Vol 70 (3) ◽  
pp. 1219-1224 ◽  
Author(s):  
Celia B. Shelton ◽  
Louise M. Temple ◽  
Paul E. Orndorff
Keyword(s):  
Lipid A ◽  
Laboratory Strain ◽  
Tracheal Ring ◽  
Phage Resistance ◽  
Dependent Manner ◽  
O Antigen ◽  
Bordetella Avium ◽  
Resistant Mutants

ABSTRACT Bordetella avium causes bordetellosis, an upper respiratory disease of birds. Commercially raised turkeys are particularly susceptible. We report here on the use of a recently described B. avium bacteriophage, Ba1, as a tool for investigating the effects of lysogeny and phage resistance on virulence. We found that lysogeny had no effect on any of the in vivo or in vitro measurements of virulence we employed. However, two-thirds (six of nine) spontaneous phage-resistant mutants of our virulent laboratory strain, 197N, were attenuated. Phage resistance was associated, in all cases, with an inability of the mutants to bind phage. Further tests of the mutants revealed that all had increased sensitivities to surfactants, and increased amounts of incomplete (O-antigen-deficient) lipopolysaccharide (LPS) compared to 197N. Hot phenol-water-extracted 197N LPS inactivated phage in a specific and dose-dependent manner. Acid hydrolysis and removal of lipid A had little effect upon the ability of isolated LPS to inactivate Ba1, suggesting that the core region and possibly the O antigen were required for phage binding. All of the mutants, with one exception, were significantly more sensitive to naive turkey serum and, without exception, significantly less able to bind to tracheal rings in vitro than 197N. Interestingly, the three phage-resistant mutants that remained virulent appeared to be O antigen deficient and were among the mutants that were the most serum sensitive and least able to bind turkey tracheal rings in vitro. This observation allowed us to conclude that even severe defects in tracheal ring binding and serum resistance manifested in vitro were not necessarily indicative of attenuation and that complete LPS may not be required for virulence.

scholarly journals RIPK1 activates distinct gasdermins in macrophages and neutrophils upon pathogen blockade of innate immune signalling

2021 ◽  
Author(s):  
Kaiwen W. Chen ◽  
Benjamin Demarco ◽  
Rosalie Heilig ◽  
Saray P Ramos ◽  
James P Grayczyk ◽  
...  
Keyword(s):  
Effector Proteins ◽  
Innate Immune ◽  
Target Cells ◽  
Caspase 8 ◽  
Dependent Manner ◽  
Wild Type ◽  
Mapk Signalling ◽  
Common Strategy ◽  
Deficient Mice

AbstractInjection of effector proteins to block host innate immune signalling is a common strategy used by many pathogenic organisms to establish an infection. Pathogenic Yersinia species for example inject the acetyltransferase YopJ into target cells to inhibit NF-κB and MAPK signalling. To counteract this, detection of YopJ activity in myeloid cells promotes the assembly of a RIPK1-caspase-8 death-inducing platform that confers antibacterial defence. While recent studies revealed that caspase-8 cleaves the pore-forming protein, gasdermin D (GSDMD) to trigger pyroptosis in macrophages, whether RIPK1 activates additional substrates downstream of caspase-8 to promote host defence is unclear. Here, we report that the related gasdermin family member gasdermin E (GSDME) is activated upon detection of YopJ activity in a RIPK1 kinase-dependent manner. Specifically, GSDME promotes neutrophil pyroptosis and IL-1β release, which is critical for anti-Yersinia defence. During in vivo infection, IL-1β neutralisation increases bacterial burden in wild type but not Gsdme-deficient mice. Thus, our study establishes GSDME as an important mediator that counteracts pathogen blockade of innate immune signalling.

scholarly journals Shigella entry unveils a calcium/calpain-dependent mechanism for inhibiting sumoylation

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Pierre Lapaquette ◽  
Sabrina Fritah ◽  
Nouara Lhocine ◽  
Alexandra Andrieux ◽  
Giulia Nigro ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Bacillary Dysentery ◽  
Shigella Flexneri ◽  
Negative Regulator ◽  
Cell Infection ◽  
Disease States ◽  
Bacterial Effectors ◽  
Dependent Mechanism

Disruption of the sumoylation/desumoylation equilibrium is associated with several disease states such as cancer and infections, however the mechanisms regulating the global SUMO balance remain poorly defined. Here, we show that infection by Shigella flexneri, the causative agent of human bacillary dysentery, switches off host sumoylation during epithelial cell infection in vitro and in vivo and that this effect is mainly mediated by a calcium/calpain-induced cleavage of the SUMO E1 enzyme SAE2, thus leading to sumoylation inhibition. Furthermore, we describe a mechanism by which Shigella promotes its own invasion by altering the sumoylation state of RhoGDIα, a master negative regulator of RhoGTPase activity and actin polymerization. Together, our data suggest that SUMO modification is essential to restrain pathogenic bacterial entry by limiting cytoskeletal rearrangement induced by bacterial effectors. Moreover, these findings identify calcium-activated calpains as powerful modulators of cellular sumoylation levels with potentially broad implications in several physiological and pathological situations.

scholarly journals Isolation and characterization of a novel temperate Escherichia coli bacteriophage, Kapi1, which modifies the O-antigen and contributes to the competitiveness of its host during colonization of the murine gastrointestinal tract.

2021 ◽  
Author(s):  
Kat Pick ◽  
Tingting Ju ◽  
Benjamin P. Willing ◽  
Tracy Lyn Raivio
Keyword(s):  
Escherichia Coli ◽  
Gastrointestinal Tract ◽  
Molecular Mechanisms ◽  
Shigella Flexneri ◽  
Simulated Intestinal Fluid ◽  
O Antigen ◽  
Isolation And Characterization

In this study, we describe the isolation and characterization of novel bacteriophage vB_EcoP_Kapi1 (Kapi1) isolated from a strain of commensal Escherichia coli inhabiting the gastrointestinal tract of healthy mice. We show that Kapi1 is a temperate phage integrated into tRNA argW of strain MP1 and describe its genome annotation and structure. Kapi1 shows limited homology to other characterized prophages but is most similar to the seroconverting phages of Shigella flexneri, and clusters taxonomically with P22-like phages. The receptor for Kapi1 is the lipopolysaccharide O-antigen, and we further show that Kapi1 alters the structure of its hosts O-antigen in multiple ways.  Kapi1 displays unstable lysogeny, and we find that lysogeny is favored during growth in simulated intestinal fluid. Furthermore, Kapi1 lysogens have a competitive advantage over their non-lysogenic counterparts both in vitro and in vivo, suggesting a role for Kapi1 during colonization. We thus report the use of MP1 and Kapi1 as a model system to explore the molecular mechanisms of mammalian colonization by E. coli to ask what the role(s) of prophages in this context might be.

scholarly journals Histone Deacetylase Inhibitors Dose-Dependently Switch Neutrophil Death from NETosis to Apoptosis

Biomolecules ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 184 ◽  
Author(s):  
Hussein J. Hamam ◽  
Nades Palaniyar
Keyword(s):  
Histone Acetylation ◽  
Histone Deacetylases ◽  
Histone Deacetylase Inhibitors ◽  
Significant Inhibition ◽  
The Body ◽  
Neutrophil Extracellular Trap ◽  
Human Neutrophils ◽  
Dependent Manner ◽  
Post Translational Modification

Acetylation is an important post translational modification of histone that plays a role in regulation of physiological and pathological process in the body. We have recently shown that the inhibition of histone deacetylases (HDAC) by low concentrations of HDAC inhibitors (HDACis), belinostat (up to 0.25 µM) and panobinostat (up to 0.04 µM) promote histone acetylation (e.g., AcH4) and neutrophil extracellular trap formation (NETosis). Clinical use of belinostat and panobinostat often leads to neutropenia and the in vivo concentrations vary with time and tissue locations. However, the effects of different concentrations of these HDACis on neutrophil death are not fully understood. We considered that increasing concentrations of belinostat and panobinostat could alter the type of neutrophil death. To test this hypothesis, we treated human neutrophils with belinostat and panobinostat in the presence or absence of agonists that promote NOX-dependent NETosis (phorbol myristate acetate or lipopolysaccharide from Escherichia coli 0128) and NOX-independent NETosis (calcium ionophores A23187 or ionomycin from Streptomyces conglobatus). Increasing concentrations of HDACis induced histone acetylation in a dose-dependent manner. ROS analyses showed that increasing concentrations of HDACis, increased the degree of NOX-derived ROS production. Higher levels (>1 µM belinostat and >0.2 µM panobinostat) of AcH4 resulted in a significant inhibition of spontaneous as well as the NOX-dependent and -independent NETosis. By contrast, the degree of neutrophil apoptosis significantly increased, particularly in non-activated cells. Collectively, this study establishes that increasing concentrations of belinostat and panobinostat initially increases NETosis but subsequently reduces NETosis or switches the form of cell death to apoptosis. This new information indicates that belinostat and panobinostat can induce different types of neutrophil death and may induce neutropenia and regulate inflammation at different concentrations.

scholarly journals Heparanase induces inflammatory cell recruitment in vivo by promoting adhesion to vascular endothelium

2014 ◽  
Vol 306 (12) ◽  
pp. C1184-C1190 ◽  
Author(s):  
Rebecca Lever ◽  
Mark J. Rose ◽  
Edward A. McKenzie ◽  
Clive P. Page
Keyword(s):  
Inflammatory Cell ◽  
Mononuclear Cells ◽  
Human Neutrophils ◽  
Inflammatory Cell Infiltrate ◽  
Dependent Manner ◽  
Cell Recruitment ◽  
Tumor Cell Migration ◽  
Inflammatory Cell Recruitment

Heparanase (HPSE1) is known to be involved in mechanisms of metastatic tumor cell migration. This enzyme selectively cleaves heparan sulfate proteoglycans (HSPG), which are ubiquitously expressed in mammals and are known to be involved in regulating the activity of an array of inflammatory mediators. In the present study, we have investigated the effects of human recombinant heparanase, the inactive precursor of this enzyme (proheparanase) and enzymatically inactivated heparanase, on inflammatory cell recruitment in the rat and on human leukocyte-endothelial adhesion in vitro. Intraperitoneal injection of heparanase (500 μg) induced a significant inflammatory cell infiltrate in the rat, as assessed by peritoneal lavage 4 h later. Intravital microscopy of the mesenteric microcirculation of anesthetized rats showed an increase in rolling and adherent cells in postcapillary venules that was sensitive to heparin, a nonselective inhibitor of heparanase activity. In vitro, heparanase augmented the adhesion of human neutrophils and mononuclear cells to human umbilical vein endothelial cells in a concentration-dependent manner. Proheparanase had similar effects to the active enzyme both with respect to leukocyte accumulation in the peritoneal cavity and adhesion in vitro. However, heat-inactivated heparanase induced cell adhesion in vitro but was without effect in vivo. Together, these data indicate a role for heparanase in inflammatory cell trafficking in vivo that appears to require enzymatic activity.

scholarly journals Real-Time Observation of Listeria monocytogenes-Phagocyte Interactions in Living Zebrafish Larvae

2009 ◽  
Vol 77 (9) ◽  
pp. 3651-3660 ◽  
Author(s):  
Jean-Pierre Levraud ◽  
Olivier Disson ◽  
Karima Kissa ◽  
Isabelle Bonne ◽  
Pascale Cossart ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Real Time ◽  
Innate Immune ◽  
Dependent Manner ◽  
Zebrafish Model ◽  
Larval Stages ◽  
Zebrafish Larvae ◽  
Key Factor ◽  
Vertebrate Model

ABSTRACT The zebrafish, Danio rerio, has become a popular vertebrate model for the study of infections, mainly because of its excellent optical accessibility at the embryonic and larval stages, when the innate immune system is already effective. We have thus tested the susceptibility of zebrafish larvae to the human pathogen Listeria monocytogenes, a gram-positive, facultative, intracellular bacterium that is known to survive and multiply in professional phagocytes and that causes fatal meningitis and abortions. Intravenous injection of early zebrafish larvae resulted in a progressive and ultimately fatal infection. Blood-borne L. monocytogenes bacteria were quickly trapped and engulfed by macrophages, an event that, for the first time, could be captured in vivo and in real time. Granulocytes also participated in the innate immune response. As in mammals, bacteria could escape the macrophage phagosome in a listeriolysin-dependent manner and accessed the cytosol; this event was critical for bacterial virulence, as listeriolysin-deficient bacteria were completely avirulent. Actin comet tails and protrusions were observed, suggesting cell-to-cell spread; these phenomena also played a role in virulence in zebrafish larvae, as actA-deficient bacteria were attenuated. These results demonstrate the relevance of the genetically tractable and optically accessible zebrafish model for the study of L. monocytogenes pathogenesis and particularly for the dissection of its interactions with phagocytes in vivo, a key factor of L. monocytogenes virulence.

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