Toxins

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281 KiB

Open AccessArticle

Staphylococcal Superantigen (TSST-1) Mutant Analysis Reveals that T Cell Activation Is Required for Biological Effects in the Rabbit Including the Cytokine Storm

by Norbert Stich, Martina Waclavicek, Nina Model and Martha M. Eibl

Toxins 2010, 2(9), 2272-2288; https://doi.org/10.3390/toxins2092272 - 9 Sep 2010

Cited by 18 | Viewed by 10387

Abstract

Staphylococcal superantigens (sAgs), such as toxic shock syndrome toxin 1 (TSST-1), induce massive cytokine production, which may result in toxic shock syndrome (TSS) and sepsis. Recently, we reported that in vitro studies in human peripheral blood mononuclear cells (PBMC) do not reflect the [...] Read more.

Staphylococcal superantigens (sAgs), such as toxic shock syndrome toxin 1 (TSST-1), induce massive cytokine production, which may result in toxic shock syndrome (TSS) and sepsis. Recently, we reported that in vitro studies in human peripheral blood mononuclear cells (PBMC) do not reflect the immunological situation of the host, because after exposure to superantigens (sAgs) in vivo, mononuclear cells (MNC) leave the circulation and migrate to organs, e.g., the spleen, liver and lung. Our experimental model of choice is the rabbit because it is comparable to humans in its sensitivity to sAg. T cell activation has been assessed by lymphocyte proliferation and IL-2 gene expression after in vivo challenge with TSST-1 and the mutant antigens; expression of the genes of proinflammatory cytokines were taken as indicators for the inflammatory reaction after the combined treatment with TSST-1 and LPS. The question as to whether the biological activities of TSST-1, e.g., lymphocyte extravasation, toxicity and increased sensitivity to LPS, are mediated by T cell activation or activation by MHC II-only, are unresolved and results are contradictory. We have addressed this question by studying these reactions in vivo, with two TSST-1 mutants: one mutated at the MHC binding site (G31R) with reduced MHC binding with residual activity still present, and the other at the T cell binding site (H135A) with no residual function detectable. Here, we report that the mutant G31R induced all the biological effects of the wild type sAg, while the mutant with non-functional TCR binding did not retain any of the toxic effects, proving the pivotal role of T cells in this system. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessArticle

How Should Staphylococcal Food Poisoning Outbreaks Be Characterized?

by Jacques-Antoine Hennekinne, Annick Ostyn, Florence Guillier, Sabine Herbin, Anne-Laure Prufer and Sylviane Dragacci

Toxins 2010, 2(8), 2106-2116; https://doi.org/10.3390/toxins2082106 - 10 Aug 2010

Cited by 89 | Viewed by 13635

Abstract

Staphylococcal food poisoning is one of the most common food-borne diseases and results from the ingestion of staphylococcal enterotoxins (SEs) preformed in food by enterotoxigenic strains of Staphylococcus aureus. To date, more than 20 SEs have been described: SEA to SElV. All SEs [...] Read more.

Staphylococcal food poisoning is one of the most common food-borne diseases and results from the ingestion of staphylococcal enterotoxins (SEs) preformed in food by enterotoxigenic strains of Staphylococcus aureus. To date, more than 20 SEs have been described: SEA to SElV. All SEs have superantigenic activity whereas only a few have been proved to be emetic, representing a potential hazard for consumers. Characterization of staphylococcal food poisoning outbreaks (SFPOs) has considerably progressed compared to 80 years ago, when staphylococci were simply enumerated and only five enterotoxins were known for qualitative detection. Today, SFPOs can be characterized by a number of approaches, such as the identification of S. aureus biovars, PCR and RT-PCR methods to identify the se genes involved, immunodetection of specific SEs, and absolute quantification by mass spectrometry. An integrated gene-to-protein approach for characterizing staphylococcal food poisoning is advocated. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessArticle

Unexpected Modulation of Recall B and T Cell Responses after Immunization with Rotavirus-like Particles in the Presence of LT-R192G

by Fatou Thiam, Cyrille Di Martino, Fabienne Bon, Annie Charpilienne, Claire Cachia, Didier Poncet, John D. Clements, Christelle Basset and Evelyne Kohli

Toxins 2010, 2(8), 2007-2027; https://doi.org/10.3390/toxins2082007 - 5 Aug 2010

Cited by 4 | Viewed by 9278

Abstract

LT-R192G, a mutant of the thermolabile enterotoxin of E. coli, is a potent adjuvant of immunization. Immune responses are generally analyzed at the end of protocols including at least 2 administrations, but rarely after a prime. To investigate this point, we compared [...] Read more.

LT-R192G, a mutant of the thermolabile enterotoxin of E. coli, is a potent adjuvant of immunization. Immune responses are generally analyzed at the end of protocols including at least 2 administrations, but rarely after a prime. To investigate this point, we compared B and T cell responses in mice after one and two intrarectal immunizations with 2/6 rotavirus-like particles (2/6-VLP) and LT-R192G. After a boost, we found, an unexpected lower B cell expansion measured by flow cytometry, despite a secondary antibody response. We then analyzed CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) and CD4⁺CD25⁺Foxp3⁻ helper T cells after in vitro (re)stimulation of mesenteric lymph node cells with the antigen (2/6-VLP), the adjuvant (LT-R192G) or both. 2/6-VLP did not activate CD4⁺CD25⁺Foxp3⁻ nor Foxp3⁺ T cells from non-immunized and 2/6-VLP immunized mice, whereas they did activate both subsets from mice immunized with 2/6-VLP in the presence of adjuvant. LT-R192G dramatically decreased CD4⁺CD25⁺Foxp3⁺ T cells from non-immunized and 2/6-VLP immunized mice but not from mice immunized with 2/6-VLP and adjuvant. Moreover, in this case, LT-R192G increased Foxp3 expression on CD4⁺CD25⁺Foxp3⁺ cells, suggesting specific Treg activation during the recall. Finally, when both 2/6-VLP and LT-R192G were used for restimulation, LT-R192G clearly suppressed both 2/6-VLP-specific CD4⁺CD25⁺Foxp3⁻ and Foxp3⁺ T cells. All together, these results suggest that LT-R192G exerts different effects on CD4⁺CD25⁺Foxp3⁺ T cells, depending on a first or a second contact. The unexpected immunomodulation observed during the recall should be considered in designing vaccination protocols. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessArticle

Uncoupling of T Cell Receptor Zeta Chain Function during the Induction of Anergy by the Superantigen, Staphylococcal Enterotoxin A

by William D. Cornwell and Thomas J. Rogers

Toxins 2010, 2(7), 1704-1717; https://doi.org/10.3390/toxins2071704 - 30 Jun 2010

Cited by 2 | Viewed by 9165

Abstract

Staphylococcus aureus enterotoxins have immunomodulatory properties. In this study, we show that Staphylococcal enterotoxin A (SEA) induces a strong proliferative response in a murine T cell clone independent of MHC class II bearing cells. SEA stimulation also induces a state of hypo-responsiveness (anergy). [...] Read more.

Staphylococcus aureus enterotoxins have immunomodulatory properties. In this study, we show that Staphylococcal enterotoxin A (SEA) induces a strong proliferative response in a murine T cell clone independent of MHC class II bearing cells. SEA stimulation also induces a state of hypo-responsiveness (anergy). We characterized the components of the T cell receptor (TCR) during induction of anergy by SEA. Most interestingly, TCR zeta chain phosphorylation was absent under SEA anergizing conditions, which suggests an uncoupling of zeta chain function. We characterize here a model system for studying anergy in the absence of confounding costimulatory signals. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessArticle

Shiga Toxin Is Transported into the Nucleoli of Intestinal Epithelial Cells via a Carrier-Dependent Process

by Boris Baibakov, Rakhilya Murtazina, Christian Elowsky, Francis M. Giardiello and Olga Kovbasnjuk

Toxins 2010, 2(6), 1318-1335; https://doi.org/10.3390/toxins2061318 - 7 Jun 2010

Cited by 5 | Viewed by 10180

Abstract

Shiga toxin (Stx) produced by the invasive Shigella dysenteriae serotype 1 (S. dysenteriae1) causes gastrointestinal and kidney complications. It has been assumed that Stx is released intracellularly after enterocyte invasion by S. dysenteriae1. However, there is little information about Stx [...] Read more.

Shiga toxin (Stx) produced by the invasive Shigella dysenteriae serotype 1 (S. dysenteriae1) causes gastrointestinal and kidney complications. It has been assumed that Stx is released intracellularly after enterocyte invasion by S. dysenteriae1. However, there is little information about Stx distribution inside S. dysenteriae1-infected enterocytes. Here, we use intestinal epithelial T84 cells to characterize the trafficking of Stx delivered into the cytosol, in ways that mimic aspects of S. dysenteriae1 infection. We find that cytoplasmic Stx is transported into nucleoli. Stx nucleolar movement is carrier- and energy-dependent. Stx binding to the nucleoli of normal human enterocytes in vitro supports possible roles for nucleolar trafficking in toxin-induced intestinal pathology. Full article

(This article belongs to the Special Issue Enterotoxins)

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Review

Jump to: Research

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Open AccessReview

Cure and Curse: E. coli Heat-Stable Enterotoxin and Its Receptor Guanylyl Cyclase C

by Philipp R. Weiglmeier, Paul Rösch and Hanna Berkner

Toxins 2010, 2(9), 2213-2229; https://doi.org/10.3390/toxins2092213 - 26 Aug 2010

Cited by 45 | Viewed by 18692

Abstract

Enterotoxigenic Escherichia coli (ETEC) associated diarrhea is responsible for roughly half a million deaths per year, the majority taking place in developing countries. The main agent responsible for these diseases is the bacterial heat-stable enterotoxin STa. STa is secreted by ETEC and after [...] Read more.

Enterotoxigenic Escherichia coli (ETEC) associated diarrhea is responsible for roughly half a million deaths per year, the majority taking place in developing countries. The main agent responsible for these diseases is the bacterial heat-stable enterotoxin STa. STa is secreted by ETEC and after secretion binds to the intestinal receptor guanylyl cyclase C (GC-C), thus triggering a signaling cascade that eventually leads to the release of electrolytes and water in the intestine. Additionally, GC-C is a specific marker for colorectal carcinoma and STa is suggested to have an inhibitory effect on intestinal carcinogenesis. To understand the conformational events involved in ligand binding to GC-C and to devise therapeutic strategies to treat both diarrheal diseases and colorectal cancer, it is paramount to obtain structural information on the receptor ligand system. Here we summarize the currently available structural data and report on physiological consequences of STa binding to GC-C in intestinal epithelia and colorectal carcinoma cells. Full article

(This article belongs to the Special Issue Enterotoxins)

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Graphical abstract

577 KiB

Open AccessReview

Staphylococcal Enterotoxins

by Irina V. Pinchuk, Ellen J. Beswick and Victor E. Reyes

Toxins 2010, 2(8), 2177-2197; https://doi.org/10.3390/toxins2082177 - 18 Aug 2010

Cited by 419 | Viewed by 39062

Abstract

Staphylococcus aureus (S. aureus) is a Gram positive bacterium that is carried by about one third of the general population and is responsible for common and serious diseases. These diseases include food poisoning and toxic shock syndrome, which are caused by [...] Read more.

Staphylococcus aureus (S. aureus) is a Gram positive bacterium that is carried by about one third of the general population and is responsible for common and serious diseases. These diseases include food poisoning and toxic shock syndrome, which are caused by exotoxins produced by S. aureus. Of the more than 20 Staphylococcal enterotoxins, SEA and SEB are the best characterized and are also regarded as superantigens because of their ability to bind to class II MHC molecules on antigen presenting cells and stimulate large populations of T cells that share variable regions on the b chain of the T cell receptor. The result of this massive T cell activation is a cytokine bolus leading to an acute toxic shock. These proteins are highly resistant to denaturation, which allows them to remain intact in contaminated food and trigger disease outbreaks. A recognized problem is the emergence of multi-drug resistant strains of S. aureus and these are a concern in the clinical setting as they are a common cause of antibiotic-associated diarrhea in hospitalized patients. In this review, we provide an overview of the current understanding of these proteins. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

Different Types of Cell Death Induced by Enterotoxins

by Chiou-Feng Lin, Chia-Ling Chen, Wei-Ching Huang, Yi-Lin Cheng, Chia-Yuan Hsieh, Chi-Yun Wang and Ming-Yuan Hong

Toxins 2010, 2(8), 2158-2176; https://doi.org/10.3390/toxins2082158 - 11 Aug 2010

Cited by 26 | Viewed by 12309

Abstract

The infection of bacterial organisms generally causes cell death to facilitate microbial invasion and immune escape, both of which are involved in the pathogenesis of infectious diseases. In addition to the intercellular infectious processes, pathogen-produced/secreted enterotoxins (mostly exotoxins) are the major weapons that [...] Read more.

The infection of bacterial organisms generally causes cell death to facilitate microbial invasion and immune escape, both of which are involved in the pathogenesis of infectious diseases. In addition to the intercellular infectious processes, pathogen-produced/secreted enterotoxins (mostly exotoxins) are the major weapons that kill host cells and cause diseases by inducing different types of cell death, particularly apoptosis and necrosis. Blocking these enterotoxins with synthetic drugs and vaccines is important for treating patients with infectious diseases. Studies of enterotoxin-induced apoptotic and necrotic mechanisms have helped us to create efficient strategies to use against these well-characterized cytopathic toxins. In this article, we review the induction of the different types of cell death from various bacterial enterotoxins, such as staphylococcal enterotoxin B, staphylococcal alpha-toxin, Panton-Valentine leukocidin, alpha-hemolysin of Escherichia coli, Shiga toxins, cytotoxic necrotizing factor 1, heat-labile enterotoxins, and the cholera toxin, Vibrio cholerae. In addition, necrosis caused by pore-forming toxins, apoptotic signaling through cross-talk pathways involving mitochondrial damage, endoplasmic reticulum stress, and lysosomal injury is discussed. Full article

(This article belongs to the Special Issue Enterotoxins)

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Graphical abstract

391 KiB

Open AccessReview

Toxin Mediated Diarrhea in the 21^st Century: The Pathophysiology of Intestinal Ion Transport in the Course of ETEC, V. cholerae and Rotavirus Infection

by Sascha Kopic and John P. Geibel

Toxins 2010, 2(8), 2132-2157; https://doi.org/10.3390/toxins2082132 - 10 Aug 2010

Cited by 55 | Viewed by 14048

Abstract

An estimated 4 billion episodes of diarrhea occur each year. As a result, 2–3 million children and 0.5–1 million adults succumb to the consequences of this major healthcare concern. The majority of these deaths can be attributed to toxin mediated diarrhea by infectious [...] Read more.

An estimated 4 billion episodes of diarrhea occur each year. As a result, 2–3 million children and 0.5–1 million adults succumb to the consequences of this major healthcare concern. The majority of these deaths can be attributed to toxin mediated diarrhea by infectious agents, such as E. coli, V. cholerae or Rotavirus. Our understanding of the pathophysiological processes underlying these infectious diseases has notably improved over the last years. This review will focus on the cellular mechanism of action of the most common enterotoxins and the latest specific therapeutic approaches that have been developed to contain their lethal effects. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

Multiple Roles of Staphylococcus aureus Enterotoxins: Pathogenicity, Superantigenic Activity, and Correlation to Antibiotic Resistance

by Elena Ortega, Hikmate Abriouel, Rosario Lucas and Antonio Gálvez

Toxins 2010, 2(8), 2117-2131; https://doi.org/10.3390/toxins2082117 - 10 Aug 2010

Cited by 142 | Viewed by 14618

Abstract

Heat-stable enterotoxins are the most notable virulence factors associated with Staphylococcus aureus, a common pathogen associated with serious community and hospital acquired diseases. Staphylococcal enterotoxins (SEs) cause toxic shock-like syndromes and have been implicated in food poisoning. But SEs also act as [...] Read more.

Heat-stable enterotoxins are the most notable virulence factors associated with Staphylococcus aureus, a common pathogen associated with serious community and hospital acquired diseases. Staphylococcal enterotoxins (SEs) cause toxic shock-like syndromes and have been implicated in food poisoning. But SEs also act as superantigens that stimulate T-cell proliferation, and a high correlation between these activities has been detected. Most of the nosocomial S. aureus infections are caused by methicillin-resistant S. aureus (MRSA) strains, and those resistant to quinolones or multiresistant to other antibiotics are emerging, leaving a limited choice for their control. This review focuses on these diverse roles of SE, their possible correlations and the influence in disease progression and therapy. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

Bacterial Heat-Stable Enterotoxins: Translation of Pathogenic Peptides into Novel Targeted Diagnostics and Therapeutics

by Jieru E. Lin, Michael Valentino, Glen Marszalowicz, Michael S. Magee, Peng Li, Adam E. Snook, Brian A. Stoecker, Chang Chang and Scott A. Waldman

Toxins 2010, 2(8), 2028-2054; https://doi.org/10.3390/toxins2082028 - 5 Aug 2010

Cited by 31 | Viewed by 15044

Abstract

Heat-stable toxins (STs) produced by enterotoxigenic bacteria cause endemic and traveler’s diarrhea by binding to and activating the intestinal receptor guanylyl cyclase C (GC-C). Advances in understanding the biology of GC-C have extended ST from a diarrheagenic peptide to a novel therapeutic agent. [...] Read more.

Heat-stable toxins (STs) produced by enterotoxigenic bacteria cause endemic and traveler’s diarrhea by binding to and activating the intestinal receptor guanylyl cyclase C (GC-C). Advances in understanding the biology of GC-C have extended ST from a diarrheagenic peptide to a novel therapeutic agent. Here, we summarize the physiological and pathophysiological role of GC-C in fluid-electrolyte regulation and intestinal crypt-villus homeostasis, as well as describe translational opportunities offered by STs, reflecting the unique characteristics of GC-C, in treating irritable bowel syndrome and chronic constipation, and in preventing and treating colorectal cancer. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

Therapeutic Down-Modulators of Staphylococcal Superantigen-Induced Inflammation and Toxic Shock

by Teresa Krakauer

Toxins 2010, 2(8), 1963-1983; https://doi.org/10.3390/toxins2081963 - 29 Jul 2010

Cited by 19 | Viewed by 14494

Abstract

Staphylococcal enterotoxin B (SEB) and related superantigenic toxins are potent stimulators of the immune system and cause a variety of diseases in humans, ranging from food poisoning to toxic shock. These toxins bind directly to major histocompatibility complex (MHC) class II molecules on [...] Read more.

Staphylococcal enterotoxin B (SEB) and related superantigenic toxins are potent stimulators of the immune system and cause a variety of diseases in humans, ranging from food poisoning to toxic shock. These toxins bind directly to major histocompatibility complex (MHC) class II molecules on antigen-presenting cells and specific Vb regions of T-cell receptors (TCR), resulting in hyperactivation of both monocytes/macrophages and T lymphocytes. Activated host cells produce massive amounts of proinflammatory cytokines and chemokines, activating inflammation and coagulation, causing clinical symptoms that include fever, hypotension, and shock. This review summarizes the in vitro and in vivo effects of staphylococcal superantigens, the role of pivotal mediators induced by these toxins in the pathogenic mechanisms of tissue injury, and the therapeutic agents to mitigate the toxic effects of superantigens. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

NetB, a Pore-Forming Toxin from Necrotic Enteritis Strains of Clostridium perfringens

by Anthony L. Keyburn, Trudi L. Bannam, Robert J. Moore and Julian I. Rood

Toxins 2010, 2(7), 1913-1927; https://doi.org/10.3390/toxins2071913 - 23 Jul 2010

Cited by 110 | Viewed by 18079

Abstract

The Clostridium perfringens necrotic enteritis B-like toxin (NetB) is a recently discovered member of the β-barrel pore-forming toxin family and is produced by a subset of avian C. perfringens type A strains. NetB is cytotoxic for avian cells and is associated with avian [...] Read more.

The Clostridium perfringens necrotic enteritis B-like toxin (NetB) is a recently discovered member of the β-barrel pore-forming toxin family and is produced by a subset of avian C. perfringens type A strains. NetB is cytotoxic for avian cells and is associated with avian necrotic enteritis. This review examines the current state of knowledge of NetB: its role in pathogenesis, its distribution and expression in C. perfringens and its vaccine potential. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

The Systemic and Pulmonary Immune Response to Staphylococcal Enterotoxins

by Sanjeev Kumar, Antoine Ménoret, Soo-Mun Ngoi and Anthony T. Vella

Toxins 2010, 2(7), 1898-1912; https://doi.org/10.3390/toxins2071898 - 21 Jul 2010

Cited by 11 | Viewed by 8564

Abstract

In response to environmental cues the human pathogen Staphylococcus aureus synthesizes and releases proteinaceous enterotoxins. These enterotoxins are natural etiologic entities of severe food poisoning, toxic shock syndrome, and acute diseases. Staphylococcal enterotoxins are currently listed as Category B Bioterrorism Agents by the [...] Read more.

In response to environmental cues the human pathogen Staphylococcus aureus synthesizes and releases proteinaceous enterotoxins. These enterotoxins are natural etiologic entities of severe food poisoning, toxic shock syndrome, and acute diseases. Staphylococcal enterotoxins are currently listed as Category B Bioterrorism Agents by the Center for Disease Control and Prevention. They are associated with respiratory illnesses, and may contribute to exacerbation of pulmonary disease. This likely stems from the ability of Staphylococcal enterotoxins to elicit powerful episodes of T cell stimulation resulting in release of pro-inflammatory cytokines. Here, we discuss the role of the immune system and potential mechanisms of disease initiation and progression. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

The Enterotoxicity of Clostridium difficile Toxins

by Xingmin Sun, Tor Savidge and Hanping Feng

Toxins 2010, 2(7), 1848-1880; https://doi.org/10.3390/toxins2071848 - 14 Jul 2010

Cited by 82 | Viewed by 14168

Abstract

The major virulence factors of Clostridium difficile infection (CDI) are two large exotoxins A (TcdA) and B (TcdB). However, our understanding of the specific roles of these toxins in CDI is still evolving. It is now accepted that both toxins are enterotoxic and [...] Read more.

The major virulence factors of Clostridium difficile infection (CDI) are two large exotoxins A (TcdA) and B (TcdB). However, our understanding of the specific roles of these toxins in CDI is still evolving. It is now accepted that both toxins are enterotoxic and proinflammatory in the human intestine. Both purified TcdA and TcdB are capable of inducing the pathophysiology of CDI, although most studies have focused on TcdA. C. difficile toxins exert a wide array of biological activities by acting directly on intestinal epithelial cells. Alternatively, the toxins may target immune cells and neurons once the intestinal epithelial barrier is disrupted. The toxins may also act indirectly by stimulating cells to produce chemokines, proinflammatory cytokines, neuropeptides and other neuroimmune signals. This review considers the mechanisms of TcdA- and TcdB-induced enterotoxicity, and recent developments in this field. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

Cholera-Like Enterotoxins and Regulatory T cells

by Christelle Basset, Fatou Thiam, Cyrille Di Martino, John Holton, John D. Clements and Evelyne Kohli

Toxins 2010, 2(7), 1774-1795; https://doi.org/10.3390/toxins2071774 - 6 Jul 2010

Cited by 13 | Viewed by 11557

Abstract

Cholera toxin (CT) and the heat-labile enterotoxin of E. coli (LT), as well as their non toxic mutants, are potent mucosal adjuvants of immunization eliciting mucosal and systemic responses against unrelated co-administered antigens in experimental models and in humans (non toxic mutants). These [...] Read more.

Cholera toxin (CT) and the heat-labile enterotoxin of E. coli (LT), as well as their non toxic mutants, are potent mucosal adjuvants of immunization eliciting mucosal and systemic responses against unrelated co-administered antigens in experimental models and in humans (non toxic mutants). These enterotoxins are composed of two subunits, the A subunit, responsible for an ADP-ribosyl transferase activity and the B subunit, responsible for cell binding. Paradoxically, whereas the whole toxins have adjuvant properties, the B subunits of CT (CTB) and of LT (LTB) have been shown to induce antigen specific tolerance when administered mucosally with antigens in experimental models as well as, recently, in humans, making them an attractive strategy to prevent or treat autoimmune or allergic disorders. Immunomodulation is a complex process involving many cell types notably antigen presenting cells and regulatory T cells (Tregs). In this review, we focus on Treg cells and cholera-like enterotoxins and their non toxic derivates, with regard to subtype, in vivo/in vitro effects and possible role in the modulation of immune responses to coadministered antigens. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

Food Poisoning and Staphylococcus aureus Enterotoxins

by María Ángeles Argudín, María Carmen Mendoza and María Rosario Rodicio

Toxins 2010, 2(7), 1751-1773; https://doi.org/10.3390/toxins2071751 - 5 Jul 2010

Cited by 856 | Viewed by 51408

Abstract

Staphylococcus aureus produces a wide variety of toxins including staphylococcal enterotoxins (SEs; SEA to SEE, SEG to SEI, SER to SET) with demonstrated emetic activity, and staphylococcal-like (SEl) proteins, which are not emetic in a primate model (SElL and [...] Read more.

Staphylococcus aureus produces a wide variety of toxins including staphylococcal enterotoxins (SEs; SEA to SEE, SEG to SEI, SER to SET) with demonstrated emetic activity, and staphylococcal-like (SEl) proteins, which are not emetic in a primate model (SElL and SElQ) or have yet to be tested (SElJ, SElK, SElM to SElP, SElU, SElU2 and SElV). SEs and SEl s have been traditionally subdivided into classical (SEA to SEE) and new (SEG to SElU2) types. All possess superantigenic activity and are encoded by accessory genetic elements, including plasmids, prophages, pathogenicity islands, νSa genomic islands, or by genes located next to the staphylococcal cassette chromosome (SCC) implicated in methicillin resistance. SEs are a major cause of food poisoning, which typically occurs after ingestion of different foods, particularly processed meat and dairy products, contaminated with S. aureus by improper handling and subsequent storage at elevated temperatures. Symptoms are of rapid onset and include nausea and violent vomiting, with or without diarrhea. The illness is usually self-limiting and only occasionally it is severe enough to warrant hospitalization. SEA is the most common cause of staphylococcal food poisoning worldwide, but the involvement of other classical SEs has been also demonstrated. Of the new SE/SEls, only SEH have clearly been associated with food poisoning. However, genes encoding novel SEs as well as SEls with untested emetic activity are widely represented in S. aureus, and their role in pathogenesis may be underestimated. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

Production, Secretion and Biological Activity of Bacillus cereus Enterotoxins

by Sonia Senesi and Emilia Ghelardi

Toxins 2010, 2(7), 1690-1703; https://doi.org/10.3390/toxins2071690 - 29 Jun 2010

Cited by 103 | Viewed by 14594

Abstract

Bacillus cereus behaves as an opportunistic pathogen frequently causing gastrointestinal diseases, and it is increasingly recognized to be responsible for severe local or systemic infections. Pathogenicity of B. cereus mainly relies on the secretion of a wide array of toxins and enzymes and [...] Read more.

Bacillus cereus behaves as an opportunistic pathogen frequently causing gastrointestinal diseases, and it is increasingly recognized to be responsible for severe local or systemic infections. Pathogenicity of B. cereus mainly relies on the secretion of a wide array of toxins and enzymes and also on the ability to undergo swarming differentiation in response to surface-sensing. In this report, the pathogenicity exerted by B. cereus toxins is described with particular attention to the regulatory mechanisms of production and secretion of HBL, Nhe and CytK enterotoxins. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

AB Toxins: A Paradigm Switch from Deadly to Desirable

by Oludare Odumosu, Dequina Nicholas, Hiroshi Yano and William Langridge

Toxins 2010, 2(7), 1612-1645; https://doi.org/10.3390/toxins2071612 - 25 Jun 2010

Cited by 75 | Viewed by 17193

Abstract

To ensure their survival, a number of bacterial and plant species have evolved a common strategy to capture energy from other biological systems. Being imperfect pathogens, organisms synthesizing multi-subunit AB toxins are responsible for the mortality of millions of people and animals annually. [...] Read more.

To ensure their survival, a number of bacterial and plant species have evolved a common strategy to capture energy from other biological systems. Being imperfect pathogens, organisms synthesizing multi-subunit AB toxins are responsible for the mortality of millions of people and animals annually. Vaccination against these organisms and their toxins has proved rather ineffective in providing long-term protection from disease. In response to the debilitating effects of AB toxins on epithelial cells of the digestive mucosa, mechanisms underlying toxin immunomodulation of immune responses have become the focus of increasing experimentation. The results of these studies reveal that AB toxins may have a beneficial application as adjuvants for the enhancement of immune protection against infection and autoimmunity. Here, we examine similarities and differences in the structure and function of bacterial and plant AB toxins that underlie their toxicity and their exceptional properties as immunomodulators for stimulating immune responses against infectious disease and for immune suppression of organ-specific autoimmunity. Full article

(This article belongs to the Special Issue Enterotoxins)

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Open AccessReview

Specificity of Interaction between Clostridium perfringens Enterotoxin and Claudin-Family Tight Junction Proteins

by Leslie A. Mitchell and Michael Koval

Toxins 2010, 2(7), 1595-1611; https://doi.org/10.3390/toxins2071595 - 24 Jun 2010

Cited by 62 | Viewed by 14222

Abstract

Clostridium perfringens enterotoxin (CPE), a major cause of food poisoning, forms physical pores in the plasma membrane of intestinal epithelial cells. The ability of CPE to recognize the epithelium is due to the C-terminal binding domain, which binds to a specific motif [...] Read more.

Clostridium perfringens enterotoxin (CPE), a major cause of food poisoning, forms physical pores in the plasma membrane of intestinal epithelial cells. The ability of CPE to recognize the epithelium is due to the C-terminal binding domain, which binds to a specific motif on the second extracellular loop of tight junction proteins known as claudins. The interaction between claudins and CPE plays a key role in mediating CPE toxicity by facilitating pore formation and by promoting tight junction disassembly. Recently, the ability of CPE to distinguish between specific claudins has been used to develop tools for studying roles for claudins in epithelial barrier function. Moreover, the high affinity of CPE to selected claudins makes CPE a useful platform for targeted drug delivery to tumors expressing these claudins. Full article

(This article belongs to the Special Issue Enterotoxins)

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Heat-Labile Enterotoxin: Beyond G _M1 Binding

by Benjamin Mudrak and Meta J. Kuehn

Toxins 2010, 2(6), 1445-1470; https://doi.org/10.3390/toxins2061445 - 14 Jun 2010

Cited by 66 | Viewed by 24637

Abstract

Enterotoxigenic Escherichia coli (ETEC) is a significant source of morbidity and mortality worldwide. One major virulence factor released by ETEC is the heat-labile enterotoxin LT, which is structurally and functionally similar to cholera toxin. LT consists of five B subunits carrying a single [...] Read more.

Enterotoxigenic Escherichia coli (ETEC) is a significant source of morbidity and mortality worldwide. One major virulence factor released by ETEC is the heat-labile enterotoxin LT, which is structurally and functionally similar to cholera toxin. LT consists of five B subunits carrying a single catalytically active A subunit. LTB binds the monosialoganglioside G_M1, the toxin’s host receptor, but interactions with A-type blood sugars and E. coli lipopolysaccharide have also been identified within the past decade. Here, we review the regulation, assembly, and binding properties of the LT B-subunit pentamer and discuss the possible roles of its numerous molecular interactions. Full article

(This article belongs to the Special Issue Enterotoxins)

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On the Interaction of Clostridium perfringens Enterotoxin with Claudins

by Anna Veshnyakova, Jonas Protze, Jan Rossa, Ingolf E. Blasig, Gerd Krause and Joerg Piontek

Toxins 2010, 2(6), 1336-1356; https://doi.org/10.3390/toxins2061336 - 8 Jun 2010

Cited by 79 | Viewed by 14648

Abstract

Clostridium perfringens causes one of the most common foodborne illnesses, which is largely mediated by the Clostridium perfringens enterotoxin (CPE). The toxin consists of two functional domains. The N-terminal region mediates the cytotoxic effect through pore formation in the plasma membrane of the [...] Read more.

Clostridium perfringens causes one of the most common foodborne illnesses, which is largely mediated by the Clostridium perfringens enterotoxin (CPE). The toxin consists of two functional domains. The N-terminal region mediates the cytotoxic effect through pore formation in the plasma membrane of the mammalian host cell. The C-terminal region (cCPE) binds to the second extracellular loop of a subset of claudins. Claudin-3 and claudin-4 have been shown to be receptors for CPE with very high affinity. The toxin binds with weak affinity to claudin-1 and -2 but contribution of these weak binding claudins to CPE-mediated disease is questionable. cCPE is not cytotoxic, however, it is a potent modulator of tight junctions. This review describes recent progress in the molecular characterization of the cCPE-claudin interaction using mutagenesis, in vitro binding assays and permeation studies. The results promote the development of recombinant cCPE-proteins and CPE-based peptidomimetics to modulate tight junctions for improved drug delivery or to treat tumors overexpressing claudins. Full article

(This article belongs to the Special Issue Enterotoxins)

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Toxin-Specific Antibodies for the Treatment of Clostridium difficile: Current Status and Future Perspectives

by Greg Hussack and Jamshid Tanha

Toxins 2010, 2(5), 998-1018; https://doi.org/10.3390/toxins2050998 - 7 May 2010

Cited by 33 | Viewed by 13244

Abstract

Therapeutic agents targeting bacterial virulence factors are gaining interest as non-antibiotic alternatives for the treatment of infectious diseases. Clostridium difficile is a Gram-positive pathogen that produces two primary virulence factors, enterotoxins A and B (TcdA and TcdB), which are responsible for Clostridium difficile [...] Read more.

Therapeutic agents targeting bacterial virulence factors are gaining interest as non-antibiotic alternatives for the treatment of infectious diseases. Clostridium difficile is a Gram-positive pathogen that produces two primary virulence factors, enterotoxins A and B (TcdA and TcdB), which are responsible for Clostridium difficile-associated disease (CDAD) and are targets for CDAD therapy. Antibodies specific for TcdA and TcdB have been shown to effectively treat CDAD and prevent disease relapse in animal models and in humans. This review summarizes the various toxin-specific antibody formats and strategies under development, and discusses future directions for CDAD immunotherapy, including the use of engineered antibody fragments with robust biophysical properties for systemic and oral delivery. Full article

(This article belongs to the Special Issue Enterotoxins)

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The Role of Lymphostatin/EHEC Factor for Adherence-1 in the Pathogenesis of Gram Negative Infection

by Jan-Michael A. Klapproth

Toxins 2010, 2(5), 954-962; https://doi.org/10.3390/toxins2050954 - 5 May 2010

Cited by 7 | Viewed by 8815

Abstract

Lymphostatin/EHEC factor for adherence-1 is a novel large toxin represented in various Gram negative bacteria, highly associated with the development of infectious diarrhea and hemolytic uremic syndrome. In vitro and in vivo experiments identified lymphostatin/EFA-1 as a toxin with a central role in [...] Read more.

Lymphostatin/EHEC factor for adherence-1 is a novel large toxin represented in various Gram negative bacteria, highly associated with the development of infectious diarrhea and hemolytic uremic syndrome. In vitro and in vivo experiments identified lymphostatin/EFA-1 as a toxin with a central role in the pathogenesis of Gram negative bacteria, responsible for bacterial adhesion, intestinal colonization, immunosuppression, and disruption of gut epithelial barrier function. Full article

(This article belongs to the Special Issue Enterotoxins)

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Cholera Toxin: An Intracellular Journey into the Cytosol by Way of the Endoplasmic Reticulum

by Naomi L. B. Wernick, Daniel J.-F. Chinnapen, Jin Ah Cho and Wayne I. Lencer

Toxins 2010, 2(3), 310-325; https://doi.org/10.3390/toxins2030310 - 5 Mar 2010

Cited by 165 | Viewed by 22450

Abstract

Cholera toxin (CT), an AB₅-subunit toxin, enters host cells by binding the ganglioside GM1 at the plasma membrane (PM) and travels retrograde through the trans-Golgi Network into the endoplasmic reticulum (ER). In the ER, a portion of CT, the enzymatic [...] Read more.

Cholera toxin (CT), an AB₅-subunit toxin, enters host cells by binding the ganglioside GM1 at the plasma membrane (PM) and travels retrograde through the trans-Golgi Network into the endoplasmic reticulum (ER). In the ER, a portion of CT, the enzymatic A1-chain, is unfolded by protein disulfide isomerase and retro-translocated to the cytosol by hijacking components of the ER associated degradation pathway for misfolded proteins. After crossing the ER membrane, the A1-chain refolds in the cytosol and escapes rapid degradation by the proteasome to induce disease by ADP-ribosylating the large G-protein Gs and activating adenylyl cyclase. Here, we review the mechanisms of toxin trafficking by GM1 and retro-translocation of the A1-chain to the cytosol. Full article

(This article belongs to the Special Issue Enterotoxins)

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