Mechanism of<i>Clostridium difficile</i>Toxin A–Induced Apoptosis in T84 Cells

Brito, Gerly A.C.; Fujji, Jun; Carneiro‐Filho, Benedito A.; Lima, Aldo A. M.; Obrig, Tom G.; Guerrant, Richard L.

doi:10.1086/344729

Cited by 113 publications

(145 citation statements)

References 57 publications

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“…Both pathways culminate in the activation of downstream executioner caspase-3. The activation of caspase-3 results in a series of events, such as cleavage of cytoskeleton proteins, activation of nucleases, and subsequent DNA fragmentation [30]. The results of the present study demonstrate that VacA induces cytochrome c release from the mitochondria into the cytoplasm in eosinophils.…”

Section: Discussionsupporting

confidence: 55%

Dual effects of Helicobacter pylori vacuolating cytotoxin on human eosinophil apoptosis in early and late periods of stimulation

Kim

Lee

et al. 2010

Eur J Immunol

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Although Helicobacter pylori infections of the gastric mucosa are characterized by the infiltration of inflammatory cells such as eosinophils, the responses of eosinophils to H. pylori vacuolating cytotoxin (VacA) have not been fully elucidated. This study investigates the role of VacA in the apoptosis of human eosinophils. We treated human eosinophils with purified H. pylori VacA and observed that induction of apoptosis is a relatively late event. Expression of cellular inhibitor of apoptosis protein (c-IAP)-2 was upregulated during the early period of VacA stimulation, and transfection with c-IAP2 siRNA augmented apoptotic cell death. VacA caused the translocation of cytoplasmic Bax to the mitochondria and increased cytochrome c release from mitochondria in eosinophils. Transfection of an EoL-1 eosinophil cell line with Bax siRNA decreased the release of cytochrome c and DNA fragmentation. Furthermore, apoptosis facilitated by Bax and cytochrome c was primarily regulated by p38 MAPK in VacA-treated eosinophils. These results suggest that the exposure of human eosinophils to H. pylori VacA induces the early upregulation of c-IAP2 and a relatively late apoptotic response, with the apoptosis progressing through a sequential pathway that includes p38 MAPK activation, Bax translocation, and cytochrome c release.

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Section: Discussionsupporting

confidence: 55%

Dual effects of Helicobacter pylori vacuolating cytotoxin on human eosinophil apoptosis in early and late periods of stimulation

Kim

Lee

et al. 2010

Eur J Immunol

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“…The GTD has been shown to target and inactivate a number of Rho-family GTPases (19,20). This inactivation has been linked to a cell rounding or cytopathic effect (CPE) (21)(22)(23)(24) and to an apoptotic cytotoxic effect (25)(26)(27)(28)(29)(30)(31)(32)(33). In tissue culture models, the apoptotic effects of TcdA and TcdB occur at toxin concentrations of picomolar or lower and are evident at 24 to 48 h postintoxication (26,28,29,(34)(35)(36).…”

mentioning

confidence: 99%

Clostridium difficile Toxins TcdA and TcdB Cause Colonic Tissue Damage by Distinct Mechanisms

et al. 2016

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e As the major cause of antibiotic-associated diarrhea, Clostridium difficile is a serious problem in health care facilities worldwide. C. difficile produces two large toxins, TcdA and TcdB, which are the primary virulence factors in disease. The respective functions of these toxins have been difficult to discern, in part because the cytotoxicity profiles for these toxins differ with concentration and cell type. The goal of this study was to develop a cell culture model that would allow a side-by-side mechanistic comparison of the toxins. Conditionally immortalized, young adult mouse colonic (YAMC) epithelial cells demonstrate an exquisite sensitivity to both toxins with phenotypes that agree with observations in tissue explants. TcdA intoxication results in an apoptotic cell death that is dependent on the glucosyltransferase activity of the toxin. In contrast, TcdB has a bimodal mechanism; it induces apoptosis in a glucosyltransferase-dependent manner at lower concentrations and glucosyltransferase-independent necrotic death at higher concentrations. The direct comparison of the responses to TcdA and TcdB in cells and colonic explants provides the opportunity to unify a large body of observations made by many independent investigators. C lostridium difficile is the most common cause of antibioticassociated diarrhea in the United States, and C. difficile infection (CDI) has been steadily increasing in prevalence and severity over the last 15 years (1-3). Symptoms of CDI can range from mild diarrhea to pseudomembranous colitis, and hallmarks of the disease include neutrophil infiltration, fluid release, and necrotic lesions in the colonic epithelium (4, 5). The bacteria produce two main virulence factors, large toxins called TcdA and TcdB (6, 7).The respective function and relative importance of each toxin in pathogenesis have been active topics of investigation. Genetic knockout experiments in C. difficile have shown that both toxins are important for disease pathology, although TcdB alone is sufficient to cause death in both the hamster and mouse models (6-8). For many years, TcdA and TcdB have been thought to act synergistically, with TcdA acting as an enterotoxin and TcdB acting as a cytotoxin (9, 10). The general term enterotoxin refers to the capacity of TcdA to induce inflammation, cytokine release, and fluid secretion in animal intoxication models (11-13). While TcdB does not always induce these same phenotypes in models, such as the ileal loop model, it has been shown to disrupt the integrity of the epithelial structure in human explant and xenograft models (14, 15). TcdB is also notably more potent as a cytotoxin in cell culture models (9, 10, 16).The toxins have an N-terminal glucosyltransferase domain (GTD) that is delivered into the host cytosol by the C-terminal portion of the protein (17, 18). The GTD has been shown to target and inactivate a number of Rho-family GTPases (19,20). This inactivation has been linked to a cell rounding or cytopathic effect (CPE) (21-24) and to an apoptotic cytotoxic ef...

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“…The activation of caspase-9, cytochrome C release, and changes in mitochondrial membrane potential indicate TxA stimulates the intrinsic pathway of apoptosis. The implication of the extrinsic pathway was also confirmed by the activation of caspase-8 and BID (Brito et al, 2002). The findings obtained by Brito et al (2002) were subsequently confirmed by Carneiro et al (2006) under both in vitro and in vivo conditions.…”

Section: Clostridium Difficile Toxin Amentioning

confidence: 68%

“…Apoptosis modulated by toxin A (TxA) was investigated in a study by Brito et al (2002) which revealed that TxA is capable of inducing cell death in T-84 cells. The involvement of caspases in the apoptosis mediated by TxA was verified with the use of fluorescent substrates specific to caspases-3, -6, -8, and -9.…”

Section: Clostridium Difficile Toxin Amentioning

confidence: 99%

Escherichia coli STb toxin induces apoptosis in intestinal epithelial cell lines

Syed

Dubreuil

2012

Microbial Pathogenesis

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Mechanism ofClostridium difficileToxin A–Induced Apoptosis in T84 Cells

Cited by 113 publications

References 57 publications

Dual effects of Helicobacter pylori vacuolating cytotoxin on human eosinophil apoptosis in early and late periods of stimulation

Dual effects of Helicobacter pylori vacuolating cytotoxin on human eosinophil apoptosis in early and late periods of stimulation

Clostridium difficile Toxins TcdA and TcdB Cause Colonic Tissue Damage by Distinct Mechanisms

Escherichia coli STb toxin induces apoptosis in intestinal epithelial cell lines

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