scholarly journals Shiga toxin suppresses noncanonical inflammasome responses to cytosolic LPS

2020 ◽  
Vol 5 (53) ◽  
pp. eabc0217
Author(s):  
Morena S. Havira ◽  
Atri Ta ◽  
Puja Kumari ◽  
Chengliang Wang ◽  
Ashley J. Russo ◽  
...  
Keyword(s):  
Host Defense ◽  
Shiga Toxin ◽  
Interleukin 1 ◽  
Immune Surveillance ◽  
Bacterial Toxin ◽  
Human Pathogen ◽  
Lps Challenge ◽  
Phage Protein ◽  
Uremic Syndrome

Inflammatory caspase–dependent cytosolic lipopolysaccharide (LPS) sensing is a critical arm of host defense against bacteria. How pathogens overcome this pathway to establish infections is largely unknown. Enterohemorrhagic Escherichia coli (EHEC) is a clinically important human pathogen causing hemorrhagic colitis and hemolytic uremic syndrome. We found that a bacteriophage-encoded virulence factor of EHEC, Shiga toxin (Stx), suppresses caspase-11–mediated activation of the cytosolic LPS sensing pathway. Stx was essential and sufficient to inhibit pyroptosis and interleukin-1 (IL-1) responses elicited specifically by cytosolic LPS. The catalytic activity of Stx was necessary for suppression of inflammasome responses. Stx impairment of inflammasome responses to cytosolic LPS occurs at the level of gasdermin D activation. Stx also suppresses inflammasome responses in vivo after LPS challenge and bacterial infection. Overall, this study assigns a previously undescribed inflammasome-subversive function to a well-known bacterial toxin, Stx, and reveals a new phage protein-based pathogen blockade of cytosolic immune surveillance.

Passive protection of purified yolk immunoglobulin administered against Shiga toxin 1 in mouse models

2010 ◽  
Vol 56 (12) ◽  
pp. 1003-1010 ◽  
Author(s):  
Qin Wang ◽  
Xiao-jun Hou ◽  
Kun Cai ◽  
Tao Li ◽  
Yue-nan Liu ◽  
...  
Keyword(s):  
Shiga Toxin ◽  
Protective Efficacy ◽  
Wide Spectrum ◽  
Egg Yolk ◽  
Chromatography Method ◽  
In Vivo Experiments ◽  
Enteric Diseases ◽  
Uremic Syndrome

Shiga toxins produced by Escherichia coli O157:H7 cause a wide spectrum of enteric diseases, such as lethal hemorrhagic colitis and hemolytic uremic syndrome. In this study, the B subunit protein of Shiga toxin type 1 (Stx1) was produced in the E. coli system, was further purified by Ni-column Affinity Chromatography method, and was then used as an immunogen to immunize laying hens for yolk immunoglobulin (IgY) production. Titers of IgY increased gradually with boosting vaccination and, finally, reached a level of 105, remaining steady over 1 year. Then the protective efficacy of IgY against Stx1 was evaluated by in vitro and in vivo experiments. It was shown that the anti-Stx1 IgY could effectively block the binding of Stx1 to the Hela cells and could protect BALB/c mice from toxin challenges. The data indicates the facility of using egg yolk IgY as a therapeutic intervention in cases of Shiga toxin intoxication.

scholarly journals Shiga Toxin Subtypes Display Dramatic Differences in Potency

2011 ◽  
Vol 79 (3) ◽  
pp. 1329-1337 ◽  
Author(s):  
Cynthia A. Fuller ◽  
Christine A. Pellino ◽  
Michael J. Flagler ◽  
Jane E. Strasser ◽  
Alison A. Weiss
Keyword(s):  
Shiga Toxin ◽  
Vero Cells ◽  
Epidemiologic Studies ◽  
Systemic Complications ◽  
Animal Models Of Disease ◽  
Uremic Syndrome ◽  
Models Of Disease ◽  
Relative Potencies

ABSTRACTPurified Shiga toxin (Stx) alone is capable of producing systemic complications, including hemolytic-uremic syndrome (HUS), in animal models of disease. Stx includes two major antigenic forms (Stx1 and Stx2), with minor variants of Stx2 (Stx2a to -h). Stx2a is more potent than Stx1. Epidemiologic studies suggest that Stx2 subtypes also differ in potency, but these differences have not been well documented for purified toxin. The relative potencies of five purified Stx2 subtypes, Stx2a, Stx2b, Stx2c, Stx2d, and activated (elastase-cleaved) Stx2d, were studiedin vitroby examining protein synthesis inhibition using Vero monkey kidney cells and inhibition of metabolic activity (reduction of resazurin to fluorescent resorufin) using primary human renal proximal tubule epithelial cells (RPTECs). In both RPTECs and Vero cells, Stx2a, Stx2d, and elastase-cleaved Stx2d were at least 25 times more potent than Stx2b and Stx2c.In vivopotency in mice was also assessed. Stx2b and Stx2c had potencies similar to that of Stx1, while Stx2a, Stx2d, and elastase-cleaved Stx2d were 40 to 400 times more potent than Stx1.

scholarly journals Experimental In Vivo Models of Bacterial Shiga Toxin-Associated Hemolytic Uremic Syndrome

2018 ◽  
Vol 28 (9) ◽  
pp. 1413-1425 ◽  
Author(s):  
Yu-Jin Jeong ◽  
Sung-Kyun Park ◽  
Sung-Jin Yoon ◽  
Young Jun Park ◽  
Moo-Seung Lee
Keyword(s):  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
In Vivo Models ◽  
Uremic Syndrome

scholarly journals Human Serum Amyloid P Component Protects againstEscherichia coliO157:H7 Shiga Toxin 2 In Vivo: Therapeutic Implications for Hemolytic‐Uremic Syndrome

2006 ◽  
Vol 193 (8) ◽  
pp. 1120-1124 ◽  
Author(s):  
Glen D. Armstrong ◽  
George L. Mulvey ◽  
Paola Marcato ◽  
Thomas P. Griener ◽  
Melvyn C. Kahan ◽  
...  
Keyword(s):  
Human Serum ◽  
Shiga Toxin ◽  
Amyloid P Component ◽  
Therapeutic Implications ◽  
Serum Amyloid P ◽  
Serum Amyloid P Component ◽  
Shiga Toxin 2 ◽  
Uremic Syndrome ◽  
Amyloid P

scholarly journals Neutrophils in Streptococcus suis Infection: From Host Defense to Pathology

2021 ◽  
Vol 9 (11) ◽  
pp. 2392
Author(s):  
Marêva Bleuzé ◽  
Marcelo Gottschalk ◽  
Mariela Segura
Keyword(s):  
Host Defense ◽  
Immune Cells ◽  
Immune Surveillance ◽  
Clinical Manifestations ◽  
Streptococcus Suis ◽  
Cellular Level ◽  
Economic Losses ◽  
Cell Type ◽  
Swine Pathogen

Streptococcus suis is a swine pathogen and zoonotic agent responsible for economic losses to the porcine industry. Infected animals may develop meningitis, arthritis, endocarditis, sepsis and/or sudden death. The pathogenesis of the infection implies that bacteria breach mucosal host barriers and reach the bloodstream, where they escape immune-surveillance mechanisms and spread throughout the organism. The clinical manifestations are mainly the consequence of an exacerbated inflammation, defined by an exaggerated production of cytokines and recruitment of immune cells. Among them, neutrophils arrive first in contact with the pathogens to combat the infection. Neutrophils initiate and maintain inflammation, by producing cytokines and deploying their arsenal of antimicrobial mechanisms. Furthermore, neutrophilic leukocytosis characterizes S. suis infection, and lesions of infected subjects contain a large number of neutrophils. Therefore, this cell type may play a role in host defense and/or in the exacerbated inflammation. Nevertheless, a limited number of studies addressed the role or functions of neutrophils in the context of S. suis infection. In this review, we will explore the literature about S. suis and neutrophils, from their interaction at a cellular level, to the roles and behaviors of neutrophils in the infected host in vivo.

scholarly journals The A1 Subunit of Shiga Toxin 2 Has Higher Affinity for Ribosomes and Higher Catalytic Activity than the A1 Subunit of Shiga Toxin 1

2015 ◽  
Vol 84 (1) ◽  
pp. 149-161 ◽  
Author(s):  
Debaleena Basu ◽  
Xiao-Ping Li ◽  
Jennifer N. Kahn ◽  
Kerrie L. May ◽  
Peter C. Kahn ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Shiga Toxin ◽  
The United States ◽  
Stem Loop ◽  
Content Type ◽  
Shiga Toxin 2 ◽  
Life Threatening ◽  
Uremic Syndrome ◽  
Ab5 Toxins

Shiga toxin (Stx)-producingEscherichia coli(STEC) infections can lead to life-threatening complications, including hemorrhagic colitis (HC) and hemolytic-uremic syndrome (HUS), which is the most common cause of acute renal failure in children in the United States. Stx1 and Stx2 are AB5 toxins consisting of an enzymatically active A subunit associated with a pentamer of receptor binding B subunits. Epidemiological evidence suggests that Stx2-producingE. colistrains are more frequently associated with HUS than Stx1-producing strains. Several studies suggest that the B subunit plays a role in mediating toxicity. However, the role of the A subunits in the increased potency of Stx2 has not been fully investigated. Here, using purified A1 subunits, we show that Stx2A1 has a higher affinity for yeast and mammalian ribosomes than Stx1A1. Biacore analysis indicated that Stx2A1 has faster association and dissociation with ribosomes than Stx1A1. Analysis of ribosome depurination kinetics demonstrated that Stx2A1 depurinates yeast and mammalian ribosomes and an RNA stem-loop mimic of the sarcin/ricin loop (SRL) at a higher catalytic rate and is a more efficient enzyme than Stx1A1. Stx2A1 depurinated ribosomes at a higher levelin vivoand was more cytotoxic than Stx1A1 inSaccharomyces cerevisiae. Stx2A1 depurinated ribosomes and inhibited translation at a significantly higher level than Stx1A1 in human cells. These results provide the first direct evidence that the higher affinity for ribosomes in combination with higher catalytic activity toward the SRL allows Stx2A1 to depurinate ribosomes, inhibit translation, and exhibit cytotoxicity at a significantly higher level than Stx1A1.

The role of Tir, EspA, and NleB in the colonization of cattle by Shiga toxin producingEscherichia coliO26:H11

2010 ◽  
Vol 56 (9) ◽  
pp. 739-747 ◽  
Author(s):  
Olga Misyurina ◽  
David J. Asper ◽  
Wanyin Deng ◽  
B. Brett Finlay ◽  
Dragan Rogan ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Shiga Toxin ◽  
Intestinal Tract ◽  
In Vivo Model ◽  
Intestinal Epithelial ◽  
Fecal Shedding ◽  
Human Intestinal Epithelial Cells ◽  
Uremic Syndrome

Shiga toxin producing Escherichia coli (STEC) O26:H11 is an enteric pathogen capable of causing severe hemorrhagic colitis that can lead to hemolytic uremic syndrome. This organism is able to colonize cattle and human intestinal epithelial cells by secreting effectors via a type III secretion system (T3SS). In this investigation, we examined the role of 2 effectors, Tir and NleB, and the structural translocator component EspA in the adherence of STEC to epithelial cells and in the colonization of cattle. Isogenic deletion mutants were constructed and using microscopy and flow cytometry compared to the wild-type strain in their ability to adhere to HEp-2 cells. A competitive assay was also used to measure the capacity of the mutants to colonize the intestinal tract of cattle, where both the mutant and the parental strains were introduced orally at the same time. Genomic DNA was extracted from enriched fecal samples collected at various time points, and quantitative real-time PCR was used to quantify bacteria. A significant reduction in fecal shedding was observed, and adherence to HEp-2 cells was decreased for the tir and espA mutants. Deletion of the nleB gene did not have a significant effect on the adherence of HEp-2 cells; however, in an in vivo model, it strongly reduced the ability of STEC O26:H11 to colonize the bovine intestinal tract.

scholarly journals Promoter Sequence of Shiga Toxin 2 (Stx2) Is Recognized In Vivo, Leading to Production of Biologically Active Stx2

mBio ◽  
2013 ◽  
Vol 4 (5) ◽  
Author(s):  
Leticia V. Bentancor ◽  
Maria P. Mejías ◽  
Alípio Pinto ◽  
Marcos F. Bilen ◽  
Roberto Meiss ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Central Nervous System ◽  
Nervous System ◽  
Hemolytic Uremic Syndrome ◽  
Shiga Toxin ◽  
Biologically Active ◽  
Eukaryotic Cells ◽  
Content Type ◽  
Uremic Syndrome

ABSTRACTShiga toxins (Stx) are the main agent responsible for the development of hemolytic-uremic syndrome (HUS), the most severe and life-threatening systemic complication of infection with enterohemorrhagicEscherichia coli(EHEC) strains. We previously described Stx2 expression by eukaryotic cells after they were transfectedin vitrowith thestx2gene cloned into a prokaryotic plasmid (pStx2). The aim of this study was to evaluate whether mammalian cells were also able to express Stx2in vivoafter pStx2 injection. Mice were inoculated by hydrodynamics-based transfection (HBT) with pStx2. We studied the survival, percentage of polymorphonuclear leukocytes in plasma, plasma urea levels, and histology of the kidneys and the brains of mice. Mice displayed a lethal dose-related response to pStx2. Stx2 mRNA was recovered from the liver, and Stx2 cytotoxic activity was observed in plasma of mice injected with pStx2. Stx2 was detected by immunofluorescence in the brains of mice inoculated with pStx2, and markers of central nervous system (CNS) damage were observed, including increased expression of glial fibrillary acidic protein (GFAP) and fragmentation of NeuN in neurons. Moreover, anti-Stx2B-immunized mice were protected against pStx2 inoculation. Our results show that Stx2 is expressedin vivofrom the wildstx2gene, reproducing pathogenic damage induced by purified Stx2 or secondary to EHEC infection.IMPORTANCEEnterohemorrhagic Shiga toxin (Stx)-producingEscherichia coli(EHEC) infections are a serious public health problem, and Stx is the main pathogenic agent associated with typical hemolytic-uremic syndrome (HUS). In contrast to the detailed information describing the molecular basis for EHEC adherence to epithelial cells, very little is known about how Stx is released from bacteria in the gut, reaching its target tissues, mainly the kidney and central nervous system (CNS). In order to develop an efficient treatment for EHEC infections, it is necessary to understand the mechanisms involved in Stx expression. In this regard, the present study demonstrates that mammals can synthesize biologically active Stx using the natural promoter associated with the Stx-converting bacteriophage genome. These results could impact the comprehension of EHEC HUS, since local eukaryotic cells transduced and/or infected by bacteriophage encoding Stx2 could be an alternative source of Stx production.

Sign in / Sign up

Export Citation Format

Share Document