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Lugo MR, Merrill AR. Development of Anti-Virulence Therapeutics against Mono-ADP-Ribosyltransferase Toxins. Toxins (Basel) 2020; 13:toxins13010016. [PMID: 33375750 PMCID: PMC7824265 DOI: 10.3390/toxins13010016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/16/2020] [Accepted: 12/23/2020] [Indexed: 12/27/2022] Open
Abstract
Mono-ADP-ribosyltransferase toxins are often key virulence factors produced by pathogenic bacteria as tools to compromise the target host cell. These toxins are enzymes that use host cellular NAD+ as the substrate to modify a critical macromolecule target in the host cell machinery. This post-translational modification of the target macromolecule (usually protein or DNA) acts like a switch to turn the target activity on or off resulting in impairment of a critical process or pathway in the host. One approach to stymie bacterial pathogens is to curtail the toxic action of these factors by designing small molecules that bind tightly to the enzyme active site and prevent catalytic function. The inactivation of these toxins/enzymes is targeted for the site of action within the host cell and small molecule therapeutics can function as anti-virulence agents by disarming the pathogen. This represents an alternative strategy to antibiotic therapy with the potential as a paradigm shift that may circumvent multi-drug resistance in the offending microbe. In this review, work that has been accomplished during the past two decades on this approach to develop anti-virulence compounds against mono-ADP-ribosyltransferase toxins will be discussed.
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Tremblay O, Thow Z, Merrill AR. Several New Putative Bacterial ADP-Ribosyltransferase Toxins Are Revealed from In Silico Data Mining, Including the Novel Toxin Vorin, Encoded by the Fire Blight Pathogen Erwinia amylovora. Toxins (Basel) 2020; 12:E792. [PMID: 33322547 PMCID: PMC7764402 DOI: 10.3390/toxins12120792] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 11/28/2020] [Accepted: 12/10/2020] [Indexed: 12/31/2022] Open
Abstract
Mono-ADP-ribosyltransferase (mART) toxins are secreted by several pathogenic bacteria that disrupt vital host cell processes in deadly diseases like cholera and whooping cough. In the last two decades, the discovery of mART toxins has helped uncover the mechanisms of disease employed by pathogens impacting agriculture, aquaculture, and human health. Due to the current abundance of mARTs in bacterial genomes, and an unprecedented availability of genomic sequence data, mART toxins are amenable to discovery using an in silico strategy involving a series of sequence pattern filters and structural predictions. In this work, a bioinformatics approach was used to discover six bacterial mART sequences, one of which was a functional mART toxin encoded by the plant pathogen, Erwinia amylovora, called Vorin. Using a yeast growth-deficiency assay, we show that wild-type Vorin inhibited yeast cell growth, while catalytic variants reversed the growth-defective phenotype. Quantitative mass spectrometry analysis revealed that Vorin may cause eukaryotic host cell death by suppressing the initiation of autophagic processes. The genomic neighbourhood of Vorin indicated that it is a Type-VI-secreted effector, and co-expression experiments showed that Vorin is neutralized by binding of a cognate immunity protein, VorinI. We demonstrate that Vorin may also act as an antibacterial effector, since bacterial expression of Vorin was not achieved in the absence of VorinI. Vorin is the newest member of the mART family; further characterization of the Vorin/VorinI complex may help refine inhibitor design for mART toxins from other deadly pathogens.
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Affiliation(s)
| | | | - A. Rod Merrill
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada; (O.T.); (Z.T.)
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3
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Abstract
A number of pathogenic bacteria utilize toxins to mediate disease in a susceptible host. The foodborne pathogen Salmonella is one of the most important and well-studied bacterial pathogens. Recently, whole genome sequence characterizations revealed the presence of multiple novel ADP-ribosylating toxins encoded by a variety of Salmonella serovars. In this review, we discuss both the classical (SpvB) and novel (typhoid toxin, ArtAB, and SboC/SeoC) ADP-ribosylating toxins of Salmonella, including the structure and function of these toxins and our current understanding of their contributions to virulence.
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Affiliation(s)
- Rachel A Cheng
- Department of Food Science, Cornell University, Ithaca, NY 14853, USA.
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, NY 14853, USA
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4
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Zou G, de Leeuw E. Neutralization of Pseudomonas auruginosa Exotoxin A by human neutrophil peptide 1. Biochem Biophys Res Commun 2018; 501:454-457. [PMID: 29738776 DOI: 10.1016/j.bbrc.2018.05.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 05/02/2018] [Indexed: 01/01/2023]
Abstract
Pseudomonas aeruginosa produces a large number of virulence factors, including the extracellular protein, Exotoxin A (ETA). Human Neutrophil Peptide 1 (HNP1) neutralizes the Exotoxin A. HNP1 belongs to the family of α-defensins, small effector peptides of the innate immune system that combat against microbial infections. Neutralization of bacterial toxins such as ETA by HNP1 is a novel biological function in addition to direct killing of bacteria. In this study, we report on the interaction between HNP-1 and Exotoxin A at the molecular level to allow for the design and development of potent antibacterial peptides as alternatives to classical antibiotics.
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Affiliation(s)
- Guozhang Zou
- U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, USA
| | - Erik de Leeuw
- Institute of Human Virology of the University of Maryland Baltimore School of Medicine, 725 West Lombard Street, Baltimore, MD 21201, USA.
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Chiu CC, Wang YC, Huang WC, Chen YH, Hung SW, Huang YT, Chuang HL, Chang YC. Differences in Genetic Background Contribute to Pseudomonas Exotoxin A-Induced Hepatotoxicity in Rats. Toxins (Basel) 2017; 9:E224. [PMID: 28714885 PMCID: PMC5535171 DOI: 10.3390/toxins9070224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/13/2017] [Accepted: 07/13/2017] [Indexed: 01/31/2023] Open
Abstract
Pseudomonas aeruginosa exotoxin A (PEA) causes severe hepatotoxicity in experimental animals and is useful in investigations of immune-mediated liver injury. However, strain differences in the sensitivity to PEA-induced hepatotoxicity in rats remains be elucidated. In this study, we determined the severity of PEA-induced hepatotoxicity in six genetically different rat strains. Male LE (Long Evans), Wistar, F344, WKY, BN/SsN and LEW rats were administered a single intravenous injection of PEA (20 μg/kg). Significantly elevated serum ALT and AST levels, massive necrosis and hemorrhage, and numerous TUNEL-positive hepatocytes were observed in BN/SsN rats. In contrast, low levels of ALT and AST as well as mild changes in liver histopathology were observed in Wistar and F344 rats. Moderate levels of hepatic injuries were observed in LE, WKY, and LEW rats. Pro-inflammatory cytokines including TNF-α, IL-2 and IL-6 serum levels were markedly increased in BN/SsN rats compared to Wistar and F344 rats. However, the hepatic levels of low density lipoprotein receptor-related protein (LRP), which functions as the PEA receptor, were not significantly different in each strain. Taken together, we suggest that BN/SsN is the most sensitive rat strain, whereas Wistar and F344 were the most resistant rat strains to PEA-induced liver damage. The different genetic background of rat strains plays an important role in the susceptibility to PEA-induced epatotoxicity that may depend on immune-regulation but not LRP receptor levels.
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Affiliation(s)
- Chien-Chao Chiu
- Animal Technology Laboratories, Agricultural Technology Research Institute, Miaoli 350, Taiwan.
| | - Yu-Chih Wang
- Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan.
| | - Wen-Ching Huang
- Department of Exercise and Health Science, National Taipei University of Nursing and Health Sciences, Taipei 112, Taiwan.
| | - Yi-Hsun Chen
- Graduate Institute of Veterinary Pathobiology, College of Veterinary Medicine, National Chung Hsing University, Taichung 402, Taiwan.
| | - Shao-Wen Hung
- Animal Technology Laboratories, Agricultural Technology Research Institute, Miaoli 350, Taiwan.
| | - Yen-Te Huang
- National Laboratory Animal Center, National Applied Research Laboratories, Taipei 115, Taiwan.
| | - Hsiao-Li Chuang
- National Laboratory Animal Center, National Applied Research Laboratories, Taipei 115, Taiwan.
| | - Yi-Chih Chang
- Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung 404, Taiwan.
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6
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Mayer K, Schröder A, Schnitger J, Stahl S, Brinkmann U. Influence of DPH1 and DPH5 Protein Variants on the Synthesis of Diphthamide, the Target of ADPRibosylating Toxins. Toxins (Basel) 2017; 9:E78. [PMID: 28245596 PMCID: PMC5371833 DOI: 10.3390/toxins9030078] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 02/20/2017] [Indexed: 01/22/2023] Open
Abstract
The diphthamide on eukaryotic translation elongation factor 2 (eEF2) is the target of ADPribosylating toxins and -derivatives that serve as payloads in targeted tumor therapy. Diphthamide is generated by seven DPH proteins; cells deficient in these (DPHko) lack diphthamide and are toxin-resistant. We have established assays to address the functionality of DPH1 (OVCA1) and DPH5 variants listed in dbSNP and cosmic databases: plasmids encoding wildtype and mutant DPHs were transfected into DPHko cells. Supplementation of DPH1 and DPH5 restores diphthamide synthesis and toxin sensitivity in DPH1ko and DPH5ko cells, respectively. Consequently, the determination of the diphthamide status of cells expressing DPH variants differentiates active and compromised proteins. The DPH1 frameshift variant L96fs* (with Nterminal 96 amino acids, truncated thereafter) and two splice isoforms lacking 80 or 140 amino acids at their N-termini failed to restore DPH1ko deficiency. The DPH1 frameshift variant R312fs* retained some residual activity even though it lacks a large C-terminal portion. DPH1 missense variants R27W and S56F retained activity while S221P had reduced activity, indicated by a decreased capability to restore diphthamide synthesis. The DPH5 nonsense or frameshift variants E60*, W136fs* and R207* (containing intact N-termini with truncations after 60, 136 or 207 amino acids, respectively) were inactive: none compensated the deficiency of DPH5ko cells. In contrast, missense variants D57G, G87R, S123C and Q170H as well as the frequently occurring DPH5 isoform delA212 retained activity. Sensitivity to ADP-ribosylating toxins and tumor-targeted immunotoxins depends on diphthamide which, in turn, requires DPH functionality. Because of that, DPH variants (in particular those that are functionally compromised) may serve as a biomarker and correlate with the efficacy of immunotoxin-based therapies.
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Affiliation(s)
- Klaus Mayer
- Roche Pharma Research & Early Development, Large Molecule Research, Roche Innovation Center Munich, Nonnenwald 2, 82377 Penzberg, Germany.
| | - Anna Schröder
- Roche Pharma Research & Early Development, Large Molecule Research, Roche Innovation Center Munich, Nonnenwald 2, 82377 Penzberg, Germany.
| | - Jerome Schnitger
- Roche Pharma Research & Early Development, Large Molecule Research, Roche Innovation Center Munich, Nonnenwald 2, 82377 Penzberg, Germany.
| | - Sebastian Stahl
- Roche Pharma Research & Early Development, Large Molecule Research, Roche Innovation Center Munich, Nonnenwald 2, 82377 Penzberg, Germany.
| | - Ulrich Brinkmann
- Roche Pharma Research & Early Development, Large Molecule Research, Roche Innovation Center Munich, Nonnenwald 2, 82377 Penzberg, Germany.
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Borowiec M, Gorzkiewicz M, Grzesik J, Walczak-Drzewiecka A, Salkowska A, Rodakowska E, Steczkiewicz K, Rychlewski L, Dastych J, Ginalski K. Towards Engineering Novel PE-Based Immunotoxins by Targeting Them to the Nucleus. Toxins (Basel) 2016; 8:E321. [PMID: 27834892 PMCID: PMC5127118 DOI: 10.3390/toxins8110321] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 11/01/2016] [Accepted: 11/02/2016] [Indexed: 12/23/2022] Open
Abstract
Exotoxin A (PE) from Pseudomonas aeruginosa is a bacterial ADP-ribosyltransferase, which can permanently inhibit translation in the attacked cells. Consequently, this toxin is frequently used in immunotoxins for targeted cancer therapies. In this study, we propose a novel modification to PE by incorporating the NLS sequence at its C-terminus, to make it a selective agent against fast-proliferating cancer cells, as a nucleus-accumulated toxin should be separated from its natural substrate (eEF2) in slowly dividing cells. Here, we report the cytotoxic activity and selected biochemical properties of newly designed PE mutein using two cellular models: A549 and HepG2. We also present a newly developed protocol for efficient purification of recombinant PE and its muteins with very high purity and activity. We found that furin cleavage is not critical for the activity of PE in the analyzed cell lines. Surprisingly, we observed increased toxicity of the toxin accumulated in the nucleus. This might be explained by unexpected nuclease activity of PE and its potential ability to cleave chromosomal DNA, which seems to be a putative alternative intoxication mechanism. Further experimental investigations should address this newly detected activity to identify catalytic residues and elucidate the molecular mechanism responsible for this action.
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Affiliation(s)
- Marta Borowiec
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Zwirki i Wigury 93, Warsaw 02-089, Poland.
| | - Michal Gorzkiewicz
- Laboratory of Cellular Immunology, Institute of Medical Biology, Polish Academy of Sciences, Lodowa 106, Lodz 93-232, Poland.
| | - Joanna Grzesik
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Zwirki i Wigury 93, Warsaw 02-089, Poland.
| | - Aurelia Walczak-Drzewiecka
- Laboratory of Cellular Immunology, Institute of Medical Biology, Polish Academy of Sciences, Lodowa 106, Lodz 93-232, Poland.
| | - Anna Salkowska
- Laboratory of Cellular Immunology, Institute of Medical Biology, Polish Academy of Sciences, Lodowa 106, Lodz 93-232, Poland.
| | | | - Kamil Steczkiewicz
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Zwirki i Wigury 93, Warsaw 02-089, Poland.
| | - Leszek Rychlewski
- BioInfoBank Institute, Sw. Marcin 80/82 r.355, Poznan 61-809, Poland.
| | - Jaroslaw Dastych
- Laboratory of Cellular Immunology, Institute of Medical Biology, Polish Academy of Sciences, Lodowa 106, Lodz 93-232, Poland.
| | - Krzysztof Ginalski
- Laboratory of Bioinformatics and Systems Biology, Centre of New Technologies, University of Warsaw, Zwirki i Wigury 93, Warsaw 02-089, Poland.
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8
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Rustandi RR, Wang F, Lancaster C, Kristopeit A, Thiriot DS, Heinrichs JH. Ion-Exchange Chromatography to Analyze Components of a Clostridium difficile Vaccine. Methods Mol Biol 2016; 1476:269-277. [PMID: 27507348 DOI: 10.1007/978-1-4939-6361-4_20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Ion-exchange (IEX) chromatography is one of many separation techniques that can be employed to analyze proteins. The separation mechanism is based on a reversible interaction between charged amino acids of a protein to the charged ligands attached to a column at a given pH. This interaction depends on both the pI and conformation of the protein being analyzed. The proteins are eluted by increasing the salt concentration or pH gradient. Here we describe the use of this technique to characterize the charge variant heterogeneities and to monitor stability of four protein antigen components of a Clostridium difficile vaccine. Furthermore, the IEX technique can be used to monitor reversion to toxicity for formaldehyde-treated Clostridium difficile toxins.
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Affiliation(s)
- Richard R Rustandi
- Vaccine Analytical Department, Merck Research Laboratories, Merck & Co., Inc., 770 Sumneytown Pike, P.O. Box 4, WP42A-30, West Point, PA, 19486, USA.
| | - Feng Wang
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Catherine Lancaster
- Vaccine Analytical Department, Merck Research Laboratories, Merck & Co., Inc., West Point, PA, USA
| | - Adam Kristopeit
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - David S Thiriot
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
| | - Jon H Heinrichs
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ, USA
- Sanofi Pasteur, Swiftwater, PA, USA
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9
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Kuznetsova MV, Karpunina TI. Cell-Mediated Hemolytic Activity of Nosocomial Pseudomonas Aeruginosa Strains. Bull Exp Biol Med 2015; 159:258-61. [PMID: 26085361 DOI: 10.1007/s10517-015-2936-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Indexed: 10/23/2022]
Abstract
Cell-mediated hemolysis and adhesion index of nosocomial P. aeruginosa strains were experimentally studied. The highest hemoglobin release was recorded after centrifugation of erythrocyte and bacterial cell suspension preincubated at 37 C. All cultures were referred to highly adherent variants. The relationship between P. aeruginosa adhesion activity and erythrocyte lysis was found only in "passive" cell-cell contact. No correlation between cell-associated hemolysis and hemolysis caused by secreted factors was detected. It seems that the cytotoxicity of the studied P. aeruginosa strains was determined by ExoU and ExoS third type secretion effectors.
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Affiliation(s)
- M V Kuznetsova
- Institute of Ecology and Genetics of Microorganisms, Ural Division of the Russian Academy of Sciences, Perm, Russia,
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10
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Tafesse FG, Guimaraes CP, Maruyama T, Carette JE, Lory S, Brummelkamp TR, Ploegh HL. GPR107, a G-protein-coupled receptor essential for intoxication by Pseudomonas aeruginosa exotoxin A, localizes to the Golgi and is cleaved by furin. J Biol Chem 2014; 289:24005-18. [PMID: 25031321 PMCID: PMC4148833 DOI: 10.1074/jbc.m114.589275] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 07/08/2014] [Indexed: 12/25/2022] Open
Abstract
A number of toxins, including exotoxin A (PE) of Pseudomonas aeruginosa, kill cells by inhibiting protein synthesis. PE kills by ADP-ribosylation of the translation elongation factor 2, but many of the host factors required for entry, membrane translocation, and intracellular transport remain to be elucidated. A genome-wide genetic screen in human KBM7 cells was performed to uncover host factors used by PE, several of which were confirmed by CRISPR/Cas9-gene editing in a different cell type. Several proteins not previously implicated in the PE intoxication pathway were identified, including GPR107, an orphan G-protein-coupled receptor. GPR107 localizes to the trans-Golgi network and is essential for retrograde transport. It is cleaved by the endoprotease furin, and a disulfide bond connects the two cleaved fragments. Compromising this association affects the function of GPR107. The N-terminal region of GPR107 is critical for its biological function. GPR107 might be one of the long-sought receptors that associates with G-proteins to regulate intracellular vesicular transport.
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Affiliation(s)
- Fikadu G Tafesse
- From the Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts 02142
| | - Carla P Guimaraes
- From the Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts 02142
| | - Takeshi Maruyama
- From the Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts 02142
| | - Jan E Carette
- the Stanford School of Medicine, Stanford, California 94305
| | - Stephen Lory
- the Harvard Medical School, Boston, Massachusetts 02115, and
| | - Thijn R Brummelkamp
- the Netherlands Cancer Institute, Postbus 90203, 1006 BE Amsterdam, The Netherlands
| | - Hidde L Ploegh
- From the Whitehead Institute for Biomedical Research and Massachusetts Institute of Technology, Cambridge, Massachusetts 02142,
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Roeder M, Nestorovich EM, Karginov VA, Schwan C, Aktories K, Barth H. Tailored cyclodextrin pore blocker protects mammalian cells from clostridium difficile binary toxin CDT. Toxins (Basel) 2014; 6:2097-114. [PMID: 25029374 PMCID: PMC4113744 DOI: 10.3390/toxins6072097] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 06/16/2014] [Accepted: 06/27/2014] [Indexed: 12/11/2022] Open
Abstract
Some Clostridium difficile strains produce, in addition to toxins A and B, the binary toxin Clostridium difficile transferase (CDT), which ADP-ribosylates actin and may contribute to the hypervirulence of these strains. The separate binding and translocation component CDTb mediates transport of the enzyme component CDTa into mammalian target cells. CDTb binds to its receptor on the cell surface, CDTa assembles and CDTb/CDTa complexes are internalised. In acidic endosomes, CDTb mediates the delivery of CDTa into the cytosol, most likely by forming a translocation pore in endosomal membranes. We demonstrate that a seven-fold symmetrical positively charged β-cyclodextrin derivative, per-6-S-(3-aminomethyl)benzylthio-β-cyclodextrin, which was developed earlier as a potent inhibitor of the translocation pores of related binary toxins of Bacillus anthracis, Clostridium botulinum and Clostridium perfringens, protects cells from intoxication with CDT. The pore blocker did not interfere with the CDTa-catalyzed ADP-ribosylation of actin or toxin binding to Vero cells but inhibited the pH-dependent membrane translocation of CDTa into the cytosol. In conclusion, the cationic β-cyclodextrin could serve as the lead compound in a development of novel pharmacological strategies against the CDT-producing strains of C. difficile.
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Affiliation(s)
- Maurice Roeder
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
| | | | - Vladimir A Karginov
- Innovative Biologics, Inc., 13455 Sunrise Valley Dr., Suite 200, Herndon, VA 20171, USA.
| | - Carsten Schwan
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany.
| | - Klaus Aktories
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, 79104 Freiburg, Germany.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
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Abstract
Bacterial sepsis is a major cause of fatality worldwide. Sepsis is a multi-step process that involves an uncontrolled inflammatory response by the host cells that may result in multi organ failure and death. Both gram-negative and gram-positive bacteria play a major role in causing sepsis. These bacteria produce a range of virulence factors that enable them to escape the immune defenses and disseminate to remote organs, and toxins that interact with host cells via specific receptors on the cell surface and trigger a dysregulated immune response. Over the past decade, our understanding of toxins has markedly improved, allowing for new therapeutic strategies to be developed. This review summarizes some of these toxins and their role in sepsis.
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Affiliation(s)
- Girish Ramachandran
- Center for Vaccine Development; Department of Medicine; University of Maryland School of Medicine; Baltimore, MD USA
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13
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Chiu CC, Huang YT, Wang YC, Chang YC, Ching YH, Chen HHC, Chuang HL. Pretreatment with lipopolysaccharide ameliorates Pseudomonas exotoxin A-induced hepatotoxicity in rats. Immunopharmacol Immunotoxicol 2013; 35:296-303. [PMID: 23384342 DOI: 10.3109/08923973.2013.764503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
CONTEXT Liver injury can be induced by various hepatotoxicants, including Pseudomonas aeruginosa exotoxin A (PEA). Our previous study indicated that PEA-induced rat hepatotoxicity was T cells and Kupffer cells dependent. Several reports have demonstrated that non-toxic doses of bacterial lipopolysaccharide (LPS) can protect liver against the chemicals-induced toxicity such as acetaminophen and concanavalin-A. OBJECTIVE This study aimed to investigate the protecting mechanisms of LPS on PEA-induced hepatotoxicity. RESULTS Rats pretreated with LPS (40 μg/kg, 12 h before PEA admission) significantly decreased animal mortality, serum enzyme (ALT, AST and T-bil) activities, histopathological changes and hepatocytes apoptosis following challenge with PEA. The concentrations of tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ) and interleukin-2 (IL-2) were reduced, but IL-6 and IL-10 were increased in the serum. In addition, prior treatment of these LPS-pretreated rats with gadolinium chloride (GdCl3), a selective Kupffer cell depletion agent, markedly enhanced liver injury after PEA administration. In contrast, the pretreatment of LPS to T-cell deficient athymic nude rats still display significant attenuation of PEA-induced liver injury. This observation further confirmed our hypothesis that LPS ameliorate PEA-hepatotoxicity was through Kupffer cells but not T cells. Moreover, LPS-induced hepatoprotection ability was neutralized by co-treatment with anti-TNF-α antibodies, but not with anti-IFN-γ antibodies. Finally, replacement of LPS with RS-LPS (Rhodobacter sphaeroides LPS), a Toll like receptor-4 (TLR-4) antagonist, resulted in severe hepatotoxicity. CONCLUSION These results suggested that Kupffer cells, TNF-α and TLR-4 play central mediator roles during the hepatoprotection against PEA-induced hepatotoxicity conferred by LPS.
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14
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Zhu C, Yang Q, Lv F, Liu L, Wang S. Conjugated polymer-coated bacteria for multimodal intracellular and extracellular anticancer activity. Adv Mater 2013; 25:1203-8. [PMID: 23280674 DOI: 10.1002/adma.201204550] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Indexed: 05/27/2023]
Affiliation(s)
- Chunlei Zhu
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
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15
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Abstract
Nucleotide sequences encoding full-length protein of Pseudomonas aeruginosa exotoxin A and its atoxic form were cloned and expressed in Escherichia coli cells. Purified recombinant exotoxin and immune rabbit sera protected mice from exotoxin A.
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Affiliation(s)
- A A Kaloshin
- I. I. Mechnikov Institute of Vaccines and Sera, Russian Academy of Medical Sciences, Moscow, Russia.
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16
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Wigelsworth DJ, Ruthel G, Schnell L, Herrlich P, Blonder J, Veenstra TD, Carman RJ, Wilkins TD, Van Nhieu GT, Pauillac S, Gibert M, Sauvonnet N, Stiles BG, Popoff MR, Barth H. CD44 Promotes intoxication by the clostridial iota-family toxins. PLoS One 2012; 7:e51356. [PMID: 23236484 PMCID: PMC3517468 DOI: 10.1371/journal.pone.0051356] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 10/31/2012] [Indexed: 12/16/2022] Open
Abstract
Various pathogenic clostridia produce binary protein toxins associated with enteric diseases of humans and animals. Separate binding/translocation (B) components bind to a protein receptor on the cell surface, assemble with enzymatic (A) component(s), and mediate endocytosis of the toxin complex. Ultimately there is translocation of A component(s) from acidified endosomes into the cytosol, leading to destruction of the actin cytoskeleton. Our results revealed that CD44, a multifunctional surface protein of mammalian cells, facilitates intoxication by the iota family of clostridial binary toxins. Specific antibody against CD44 inhibited cytotoxicity of the prototypical Clostridium perfringens iota toxin. Versus CD44+ melanoma cells, those lacking CD44 bound less toxin and were dose-dependently resistant to C. perfringens iota, as well as Clostridium difficile and Clostridium spiroforme iota-like, toxins. Purified CD44 specifically interacted in vitro with iota and iota-like, but not related Clostridium botulinum C2, toxins. Furthermore, CD44 knockout mice were resistant to iota toxin lethality. Collective data reveal an important role for CD44 during intoxication by a family of clostridial binary toxins.
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Affiliation(s)
- Darran J. Wigelsworth
- Integrated Toxicology Division, Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Gordon Ruthel
- Core Imaging Facility, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, United States of America
| | - Leonie Schnell
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
| | - Peter Herrlich
- Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany
| | - Josip Blonder
- Laboratory of Proteomics and Analytical Technologies, National Cancer Institute, Frederick, Maryland, United States of America
| | - Timothy D. Veenstra
- Laboratory of Proteomics and Analytical Technologies, National Cancer Institute, Frederick, Maryland, United States of America
| | | | | | - Guy Tran Van Nhieu
- Department of Intracellular Communications and Infectious Microorganisms, College of France, Paris, France
| | - Serge Pauillac
- Institut Pasteur, Unité des Bactéries anaérobies et Toxines, Paris, France
| | - Maryse Gibert
- Institut Pasteur, Unité des Bactéries anaérobies et Toxines, Paris, France
| | - Nathalie Sauvonnet
- Institut Pasteur, Unité de Biologie des Interactions Cellulaires, Paris, France
| | - Bradley G. Stiles
- Biology Department, Wilson College, Chambersburg, Pennsylvania, United States of America
- * E-mail: (BGS); (HB); (MRP)
| | - Michel R. Popoff
- Institut Pasteur, Unité des Bactéries anaérobies et Toxines, Paris, France
- * E-mail: (BGS); (HB); (MRP)
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Ulm, Germany
- * E-mail: (BGS); (HB); (MRP)
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17
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Du X, Youle RJ, FitzGerald DJ, Pastan I. Pseudomonas exotoxin A-mediated apoptosis is Bak dependent and preceded by the degradation of Mcl-1. Mol Cell Biol 2010; 30:3444-52. [PMID: 20457813 PMCID: PMC2897547 DOI: 10.1128/mcb.00813-09] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Revised: 01/25/2010] [Accepted: 04/29/2010] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas exotoxin A (PE) is a bacterial toxin that arrests protein synthesis and induces apoptosis. Here, we utilized mouse embryo fibroblasts (MEFs) deficient in Bak and Bax to determine the roles of these proteins in cell death induced by PE. PE induced a rapid and dose-dependent induction of apoptosis in wild-type (WT) and Bax knockout (Bax(-/-)) MEFs but failed in Bak knockout (Bak(-/-)) and Bax/Bak double-knockout (DKO) MEFs. Also a loss of mitochondrial membrane potential was observed in WT and Bax(-/-) MEFs, but not in Bak(-/-) or in DKO MEFs, indicating an effect of PE on mitochondrial permeability. PE-mediated inhibition of protein synthesis was identical in all 4 cell lines, indicating that differences in killing were due to steps after the ADP-ribosylation of EF2. Mcl-1, but not Bcl-x(L), was rapidly degraded after PE treatment, consistent with a role for Mcl-1 in the PE death pathway. Bak was associated with Mcl-1 and Bcl-x(L) in MEFs and uncoupled from suppressed complexes after PE treatment. Overexpression of Mcl-1 and Bcl-x(L) inhibited PE-induced MEF death. Our data suggest that Bak is the preferential mediator of PE-mediated apoptosis and that the rapid degradation of Mcl-1 unleashes Bak to activate apoptosis.
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Affiliation(s)
- Xing Du
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - Richard J. Youle
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - David J. FitzGerald
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
| | - Ira Pastan
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892
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18
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Carette JE, Guimaraes CP, Varadarajan M, Park AS, Wuethrich I, Godarova A, Kotecki M, Cochran BH, Spooner E, Ploegh HL, Brummelkamp TR. Haploid genetic screens in human cells identify host factors used by pathogens. Science 2009; 326:1231-5. [PMID: 19965467 DOI: 10.1126/science.1178955] [Citation(s) in RCA: 404] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Loss-of-function genetic screens in model organisms have elucidated numerous biological processes, but the diploid genome of mammalian cells has precluded large-scale gene disruption. We used insertional mutagenesis to develop a screening method to generate null alleles in a human cell line haploid for all chromosomes except chromosome 8. Using this approach, we identified host factors essential for infection with influenza and genes encoding important elements of the biosynthetic pathway of diphthamide, which are required for the cytotoxic effects of diphtheria toxin and exotoxin A. We also identified genes needed for the action of cytolethal distending toxin, including a cell-surface protein that interacts with the toxin. This approach has both conceptual and practical parallels with genetic approaches in haploid yeast.
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Affiliation(s)
- Jan E Carette
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
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19
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Morlon-Guyot J, Méré J, Bonhoure A, Beaumelle B. Processing of Pseudomonas aeruginosa exotoxin A is dispensable for cell intoxication. Infect Immun 2009; 77:3090-9. [PMID: 19380469 PMCID: PMC2708563 DOI: 10.1128/iai.01390-08] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 01/07/2009] [Accepted: 04/13/2009] [Indexed: 01/09/2023] Open
Abstract
Exotoxin A is a major virulence factor of Pseudomonas aeruginosa. This toxin binds to a specific receptor on animal cells, allowing endocytosis of the toxin. Once in endosomes, the exotoxin can be processed by furin to generate a C-terminal toxin fragment that lacks the receptor binding domain and is retrogradely transported to the endoplasmic reticulum for retrotranslocation to the cytosol through the Sec61 channel. The toxin then blocks protein synthesis by ADP ribosylation of elongation factor 2, thereby triggering cell death. A shorter intracellular route has also been described for this toxin. It involves direct translocation of the entire toxin from endosomes to the cytosol and therefore does not rely on furin-mediated cleavage. To examine the implications of endosomal translocation in the intoxication process, we investigated whether the toxin required furin-mediated processing in order to kill cells. We used three different approaches. We first fused to the N terminus of the toxin proteins with different unfolding abilities so that they inhibited or did not inhibit endosomal translocation of the chimera. We then assayed the amount of toxin fragments delivered to the cytosol during cell intoxication. Finally we used furin inhibitors and examined the fate and intracellular localization of the toxin and its receptor. The results showed that exotoxin cytotoxicity results largely from endosomal translocation of the entire toxin. We found that the C-terminal fragment was unstable in the cytosol.
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20
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Wolf P, Elsässer-Beile U. Pseudomonas exotoxin A: from virulence factor to anti-cancer agent. Int J Med Microbiol 2009; 299:161-76. [PMID: 18948059 DOI: 10.1016/j.ijmm.2008.08.003] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 07/07/2008] [Accepted: 08/13/2008] [Indexed: 11/24/2022] Open
Abstract
The pathogenic bacterium Pseudomonas aeruginosa has the ability to cause severe acute and chronic infections in humans. Pseudomonas exotoxin A (PE) is the most toxic virulence factor of this bacterium. It has ADP-ribosylation activity and decisively affects the protein synthesis of the host cells. The cytotoxic pathways of PE have been elucidated, and it could be shown that PE uses several molecular strategies developed under evolutionary pressure for effective killing. Interestingly, a medical benefit from this molecule has also been ascertained in recent years and several PE-based immunotoxins have been constructed and tested in preclinical and clinical trials against different cancers. In these molecules, the enzymatic active domain of PE is specifically targeted to tumor-related antigens. This review describes the current knowledge about the cytotoxic pathways of PE. Additionally, it summarizes preclinical and clinical trials of PE-based immunotoxins and furthermore discusses current problems and answers with these agents.
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Affiliation(s)
- Philipp Wolf
- Department of Urology, University of Freiburg, Germany.
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21
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Chuang HL, Huang YT, Chiu CC, Chen HHC, Chu YY, Chen TH. Influence of age on susceptibility to Pseudomonas aeruginosa exotoxin A-induced hepatotoxicity in Long-Evans rats. J Vet Med Sci 2009; 71:163-9. [PMID: 19262026 DOI: 10.1292/jvms.71.163] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Epidemiological investigations suggest that increased age is associated with susceptibility to infection. Pseudomonas aeruginosa (P. aeruginosa) infection and associated exotoxin A (PEA) toxicity have been reported in hospitalized elderly patients and young children with cystic fibrosis. The present study investigated age-related differences in PEA-induced hepatotoxicity in post weaning (PW, 3 weeks), young adult (YA, 12 weeks), and mature adult (MA, 60-64 weeks) rats. PEA (20 microg/kg) was injected intraveneously and mortality, clinical chemistry, hepatic histopathology, TUNEL (Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling) and PCNA (Proliferating cell nuclear antigen) staining, and serum cytokine levels were assessed at specific time points, up to 72 hr post-exposure (HPE). Mortality in MA rats was 100% at less than 48 HPE. Serum ALT levels in MA rats were approximately 5-fold greater than levels in PW and YA rats at 36 HPE. MA rat liver histological sections showed diffuse hepatocellular necrosis. In contrast, hepatocellular apoptosis, demonstrable by the TUNEL method, was noted simply in the periportal and midzonal regions from 36 to 48 HPE. Increased morphological mitoses and PCNA-positive hepatocytes were seen in PW and YA rats at 72 HPE. These parameters were correlated with age-dependent significant increases in TNF-alpha, IL-2, IL-6, and IL-18 levels. These data suggest that inflammatory cytokines play an important role in age-related differences in PEA-induced hepatotoxicity. Moreover, these cytokines might correlate with different patterns histopathologic features at various ages.
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Affiliation(s)
- Hsiao-Li Chuang
- Department of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
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22
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Chuang HL, Chiu CC, Chen TH, Chen HHC, Chu YY, Huang YT. Different bacteria species lipopolysaccharide co-exposure with Pseudomonas exotoxin A on multiple organ injury induction. Immunopharmacol Immunotoxicol 2009; 31:616-24. [PMID: 19874231 DOI: 10.3109/08923970902926402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The present study investigated the effect of different bacterial species lipopolysaccharide plus Pseudomonas exotoxin A (LPS/PEA) on the induction of multiple organ injury (MOI). Rats were injected with various LPS from Salmonella (SAE, SAT), E. coli (EB4, EB5), or P. aeruginosa (PAL) and PEA showed a greater mortality in the SAE/PEA and SAT/PEA groups. Histological alterations, serum enzymes, and cytokines changes were severer in the SAE/PEA group than the EB4/PEA or PAL/PEA group. EB4/PEA and PAL/PEA failed to induce MOI, even at the LPS doses increased up to 2-4- and 4-8-fold, respectively. Rats co-treated with Salmonella lipid A/PEA developed severer MOI than the E. coli lipid A/PEA. The results indicated the critical roles of MOI induction, which were related to LPS derived from appropriate bacterial species.
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Affiliation(s)
- Hsiao-Li Chuang
- Department of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
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23
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Chiu CC, Chen HHC, Chuang HL, Chung TC, Chen SD, Huang YT. Pseudomonas aeruginosa exotoxin A-induced hepatotoxicity: an animal model in rats. J Vet Med Sci 2009; 71:1-8. [PMID: 19194069 DOI: 10.1292/jvms.71.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pseudomonas aeruginosa exotoxin A (PEA) has been generally used to induce liver injury in mice for experimental study. No PEA-induced hepatotoxicity study has ever been conducted in rats, although rats are the most common rodents used in toxicologic bioassay and pharmacological evaluation. The present study was conducted in male Wistar rats that were injected (i.v.) with PEA at doses of 0, 10, 20, 30 or 40 microg/kg body weight and evaluated at 12, 24, 36, 48 and 60 hr post-exposure (HPE). Rats exposed to PEA at 40 microg/kg died before 36 HPE, and the mortality was dose and time dependent. Liver injury was noted as increases in serum enzymes, along with alterations of liver histology in the 40 microg/kg group at 12 HPE. TUNEL-positive staining indicative of hepatocyte apoptosis was observed in the 20 microg/kg group at 12 HPE. Significant levels of DNA fragmentation ladder were observed in the 30 microg/kg group starting at 24 HPE. Serum levels of TNF-alpha was increased in the 30 and 40 microg/kg groups at 48 and 24 HPE, respectively. Other cytokines, such as IL-2, IL-6, and IL-10 were also increased at various doses and times. Furthermore, the elevated serum hepatic index levels decreased significantly by dexamethasone pretreatment. In contrast, these markers were exacerbated by co-administration of a non-toxic dose LPS. In overall evaluation, the PEA-induced liver injury can be used as a model for study of hyperimmune-mediated hepatotoxicity.
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Affiliation(s)
- Chien-Chao Chiu
- Department of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
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24
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Chen H, Gao J, Lu Y, Kou G, Zhang H, Fan L, Sun Z, Guo Y, Zhong Y. Preparation and characterization of PE38KDEL-loaded anti-HER2 nanoparticles for targeted cancer therapy. J Control Release 2008; 128:209-16. [PMID: 18450313 DOI: 10.1016/j.jconrel.2008.03.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2007] [Revised: 02/19/2008] [Accepted: 03/11/2008] [Indexed: 11/23/2022]
Abstract
The clinical use of immunotoxins is severely limited by nonspecific toxicity. To overcome this limitation, PE38KDEL was used as a model protein toxin to prepare PE38KDEL-loaded poly(lactic-co-glycolic acid) (PLGA) antibody modified nanoparticles (NPs), which were covalently conjugated with Fab' fragments of a humanized anti-HER2 monoclonal antibody (rhuMAbHER2) by a two-step carbodiimide method. The characterization of the PE38KDEL-loaded nanoparticles-anti-Fab' bioconjugates (PE-NPs-HER), such as particle size, zeta potential and morphology, were evaluated by dynamic light-scattering detector and transmission electron microscope (TEM). Micro BCA assay was used to determine the drug encapsulation efficiency and the quantity of Fab' conjugated with NPs. The binding affinity and internalization efficiency of PE-NPs-HER were demonstrated by flow cytometry and laser-scanning confocal microscopy. In comparison with PE38KDEL-loaded nanoparticles (PE-NPs) that lack anti-HER2 Fab', PE-NPs-HER had superior in vitro cytotoxicity against HER2-overexpressing breast cancer cell lines. Progressively, PE-NPs-HER has superior protective antitumor activity in HER2-overexpressing tumor-bearing mice than the control immunotoxin PE-HER constructed by chemically coupling PE38KDEL to rhuMAbHER2. Most strikingly, in developed HER2-overexpressing tumor xenograft model, administration of PE-NPs-HER (0.9 mg/kg) showed a much better therapeutic efficacy in inhibiting tumor growth compared with PE-HER and other controls: final mean tumor load was 13+/-6 mm(3) (mean+/-SD; n=8, significantly smaller than all other groups by ANOVA at 95% confidence interval). In addition, PE-NPs-HER were well tolerated in mice with a much higher MTD (maximally tolerated dose) than PE-HER (2.92 mg/kg vs. 0.92 mg/kg), indicating the systemic toxicity of PE38KDEL was dramatically reduced by PLGA encapsulation. Thus, the bioconjugates PE-NPs-HER may represent a potentially useful strategy for cancer therapy.
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Affiliation(s)
- Huaiwen Chen
- Department of Pharmaceutical Science, College of Pharmacy, Second Military Medical University, 325 Guo He Road, Shanghai 200433, People's Republic of China
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25
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Abstract
Bacterial pathogens utilize toxins to modify or kill host cells. The bacterial ADP-ribosyltransferases are a family of protein toxins that covalently transfer the ADP-ribose portion of NAD to host proteins. Each bacterial ADP-ribosyltransferase toxin modifies a specific host protein(s) that yields a unique pathology. These toxins possess the capacity to enter a host cell or to use a bacterial Type III apparatus for delivery into the host cell. Advances in our understanding of bacterial toxin action parallel the development of biophysical and structural biology as well as our understanding of the mammalian cell. Bacterial toxins have been utilized as vaccines, as tools to dissect host cell physiology, and more recently for the development of novel therapies to treat human disease.
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Affiliation(s)
- Qing Deng
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
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26
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Ornatowski W, Poschet JF, Perkett E, Taylor-Cousar JL, Deretic V. Elevated furin levels in human cystic fibrosis cells result in hypersusceptibility to exotoxin A-induced cytotoxicity. J Clin Invest 2007; 117:3489-97. [PMID: 17948127 PMCID: PMC2030457 DOI: 10.1172/jci31499] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Accepted: 08/14/2007] [Indexed: 11/17/2022] Open
Abstract
Progressive pulmonary disease and infections with Pseudomonas aeruginosa remain an intractable problem in cystic fibrosis (CF). At the cellular level, CF is characterized by organellar hyperacidification, which results in altered protein and lipid glycosylation. Altered pH of the trans-Golgi network (TGN) may further disrupt the protein processing and packaging that occurs in this organelle. Here we measured activity of the major TGN endoprotease furin and demonstrated a marked upregulation in human CF cells. Increased furin activity was linked to elevated production in CF of the immunosuppressive and tissue remodeling cytokine TGF-beta and its downstream effects, including macrophage deactivation and augmented collagen secretion by epithelial cells. As furin is responsible for the proteolytic processing of a range of endogenous and exogenous substrates including growth factors and bacterial toxins, we determined that elevated furin-dependent activation of exotoxin A caused increased cell death in CF respiratory epithelial cells compared with genetically matched CF transmembrane conductance regulator-corrected cells. Thus elevated furin levels in CF respiratory epithelial cells contributes to bacterial toxin-induced cell death, fibrosis, and local immunosuppression. These data suggest that the use of furin inhibitors may represent a strategy for pharmacotherapy in CF.
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Affiliation(s)
- Wojciech Ornatowski
- Department of Molecular Genetics and Microbiology,
Department of Cell Biology and Physiology,
Department of Pediatrics, and
Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
| | - Jens F. Poschet
- Department of Molecular Genetics and Microbiology,
Department of Cell Biology and Physiology,
Department of Pediatrics, and
Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
| | - Elizabeth Perkett
- Department of Molecular Genetics and Microbiology,
Department of Cell Biology and Physiology,
Department of Pediatrics, and
Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
| | - Jennifer L. Taylor-Cousar
- Department of Molecular Genetics and Microbiology,
Department of Cell Biology and Physiology,
Department of Pediatrics, and
Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
| | - Vojo Deretic
- Department of Molecular Genetics and Microbiology,
Department of Cell Biology and Physiology,
Department of Pediatrics, and
Department of Internal Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
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27
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Chang JH, Kwon HY. Expression of 14-3-3delta, cdc2 and cyclin B proteins related to exotoxin A-induced apoptosis in HeLa S3 cells. Int Immunopharmacol 2007; 7:1185-91. [PMID: 17630197 DOI: 10.1016/j.intimp.2007.05.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2006] [Revised: 04/20/2007] [Accepted: 05/02/2007] [Indexed: 12/11/2022]
Abstract
After reports on regression of cancer in humans and animals infected with microbial pathogens date back more than 100 years, much effort has been spent over the years in developing wild type or attenuated bacterial and purified bacterial proteins for the treatment of cancer. Pseudomonas aeruginosa exotoxin A (ETA) is known to inhibit cell growth and trigger significant cell death in various cancer cells. Although ETA induces apoptosis of cancer cells, its exact mechanism of action is not yet known. Four different assays were performed in this study: morphological assessment of apoptotic cells, cell cytotoxicity, cell cycle analysis and Western blot analysis. The proliferation and survival in the cells treated with ETA was decreased. In addition, percentages of apoptotic HeLa S(3) cells treated with ETA were increased. ETA-induced apoptosis rates were confirmed to have increased in a dose-dependent manner through annexin V binding assay. Flow cytometric analysis was examined to ascertain whether ETA could regulate cell cycle in HeLa S(3) cells. ETA treatment demonstrated that the expression of 14-3-3delta proteins was increased, while expression of cdc and cyclin B proteins was decreased, suggesting that ETA induces cell cycle arrest and then progresses to apoptosis. Therefore, these results suggest that P. aeruginosa ETA induced apoptosis in HeLa S(3) cells.
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Affiliation(s)
- Jeong-Hyun Chang
- Department of Clinical Laboratory Science, College of Health Sciences, Catholic University of Pusan, Busan 609-757, Korea.
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28
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Baatar D, Olkhanud P, Newton D, Sumitomo K, Biragyn A. CCR4-expressing T cell tumors can be specifically controlled via delivery of toxins to chemokine receptors. J Immunol 2007; 179:1996-2004. [PMID: 17641067 PMCID: PMC2262935 DOI: 10.4049/jimmunol.179.3.1996] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Expression of chemokine receptors by tumors, specifically CCR4 on cutaneous T cell lymphomas, is often associated with a poor disease outcome. To test the hypothesis that chemokine receptor-expressing tumors can be successfully controlled by delivering toxins through their chemokine receptors, we have generated fusion proteins designated chemotoxins: chemokines fused with toxic moieties that are nontoxic unless delivered into the cell cytosol. We demonstrate that chemokines fused with human RNase eosinophil-derived neurotoxin or with a truncated fragment of Pseudomonas exotoxin 38 are able to specifically kill tumors in vitro upon internalization through their respective chemokine receptors. Moreover, treatment with the thymus and activation-regulated chemokine (CCL17)-expressing chemotoxin efficiently eradicated CCR4-expressing cutaneous T cell lymphoma/leukemia established in NOD-SCID mice. Taken together, this work represents a novel concept that may allow control of growth and dissemination of tumors that use chemokine receptors to metastasize and circumvent immunosurveillance.
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MESH Headings
- ADP Ribose Transferases/genetics
- ADP Ribose Transferases/toxicity
- Animals
- Antineoplastic Agents/metabolism
- Antineoplastic Agents/toxicity
- Bacterial Toxins/genetics
- Bacterial Toxins/toxicity
- Cell Death/genetics
- Cell Death/immunology
- Cell Line
- Cell Line, Tumor
- Chemokine CCL17
- Chemokines, CC/administration & dosage
- Chemokines, CC/genetics
- Chemokines, CC/toxicity
- Cytotoxicity, Immunologic/genetics
- Eosinophil-Derived Neurotoxin/genetics
- Eosinophil-Derived Neurotoxin/toxicity
- Exotoxins/genetics
- Exotoxins/toxicity
- Female
- Humans
- Immunotoxins/genetics
- Immunotoxins/toxicity
- Leukemia-Lymphoma, Adult T-Cell/immunology
- Leukemia-Lymphoma, Adult T-Cell/metabolism
- Leukemia-Lymphoma, Adult T-Cell/pathology
- Leukemia-Lymphoma, Adult T-Cell/therapy
- Mice
- Mice, Inbred NOD
- Mice, SCID
- Neoplasm Recurrence, Local
- Receptors, CCR4
- Receptors, Chemokine/biosynthesis
- Receptors, Chemokine/metabolism
- Viral Proteins/genetics
- Viral Proteins/toxicity
- Virulence Factors/genetics
- Virulence Factors/toxicity
- Pseudomonas aeruginosa Exotoxin A
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Affiliation(s)
- Dolgor Baatar
- Laboratory of Immunology, Gerontology Research Center, National Institute on Aging, Baltimore, MD 21224
| | - Purevdorj Olkhanud
- Laboratory of Immunology, Gerontology Research Center, National Institute on Aging, Baltimore, MD 21224
| | - Dianne Newton
- Department of Microbiology, SAIC-Frederick, National Cancer Institute, Frederick, MD 21702
| | - Kenya Sumitomo
- Laboratory of Immunology, Gerontology Research Center, National Institute on Aging, Baltimore, MD 21224
| | - Arya Biragyn
- Laboratory of Immunology, Gerontology Research Center, National Institute on Aging, Baltimore, MD 21224
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29
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Abstract
The group B streptococcus (GBS) is an important human pathogen with the ability to cause invasive disease. To do so, the bacteria must invade host cells. It has been well documented that GBS are able to invade a variety of nonphagocytic host cell types, and this process is thought to involve a number of pathogen-host cell interactions. While some of the molecular aspects of the GBS-host cell invasion process have been characterized, many events still remain unclear. The objective of this investigation was to evaluate the role of the Rho-family GTPases Rac, Rho, and Cdc42 in GBS invasion into epithelial cells. The epithelial cell invasion process was modeled using HeLa 229 cell culture. Treatment of HeLa cells with 10 microM compactin, a pan-GTPase inhibitor, abolished GBS internalization, suggesting that GTPases are involved in the GBS invasion process. The addition of Toxin B or exoenzyme C3 to HeLa cells before GBS infection reduced invasion by 50%, further suggesting that the Rho-family GTPases are involved in GBS entry. Examining invasion of GBS into HeLa cells with altered genetic backgrounds was used to confirm these findings; GBS invasion into HeLa cells transiently transfected with dominant negative Rac1, Cdc42, or RhoA reduced invasion by 75%, 51%, and 42%, respectively. Results of this study suggest that the Rho-family GTPases are required for efficient invasion of HeLa cells by GBS.
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Affiliation(s)
- Carey-Ann D Burnham
- The Department of Laboratory Medicine and Pathology, The University of Alberta, Edmonton, AB, Canada
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30
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Balachandran P, Dragone L, Garrity-Ryan L, Lemus A, Weiss A, Engel J. The ubiquitin ligase Cbl-b limits Pseudomonas aeruginosa exotoxin T-mediated virulence. J Clin Invest 2007; 117:419-27. [PMID: 17235393 PMCID: PMC1765809 DOI: 10.1172/jci28792] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Accepted: 11/21/2006] [Indexed: 11/17/2022] Open
Abstract
Pseudomonas aeruginosa, an important cause of opportunistic infections in humans, delivers bacterial cytotoxins by type III secretion directly into the host cell cytoplasm, resulting in disruption of host cell signaling and host innate immunity. However, little is known about the fate of the toxins themselves following injection into the host cytosol. Here, we show by both in vitro and in vivo studies that the host ubiquitin ligase Cbl-b interacts with the type III-secreted effector exotoxin T (ExoT) and plays a key role in vivo in limiting bacterial dissemination mediated by ExoT. We demonstrate that, following polyubiquitination, ExoT undergoes regulated proteasomal degradation in the host cell cytosol. ExoT interacts with the E3 ubiquitin ligase Cbl-b and Crk, the substrate for the ExoT ADP ribosyltransferase (ADPRT) domain. The efficiency of degradation is dependent upon the activity of the ADPRT domain. In mouse models of acute pneumonia and systemic infection, Cbl-b is specifically required to limit the dissemination of ExoT-producing bacteria whereas c-Cbl plays no detectable role. To the best of our knowledge, this represents the first identification of a mammalian gene product that is specifically required for in vivo resistance to disease mediated by a type III-secreted effector.
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Affiliation(s)
- Priya Balachandran
- Program in Microbial Pathogenesis and Host Defense,
Department of Medicine,
Division of Pediatric Immunology/Rheumatology, Department of Pediatrics,
Biomedical Sciences Graduate Program,
Departments of Microbiology and Immunology,
Howard Hughes Medical Institute,
Division of Rheumatology, Department of Medicine, and
Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, San Francisco, California, USA
| | - Leonard Dragone
- Program in Microbial Pathogenesis and Host Defense,
Department of Medicine,
Division of Pediatric Immunology/Rheumatology, Department of Pediatrics,
Biomedical Sciences Graduate Program,
Departments of Microbiology and Immunology,
Howard Hughes Medical Institute,
Division of Rheumatology, Department of Medicine, and
Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, San Francisco, California, USA
| | - Lynne Garrity-Ryan
- Program in Microbial Pathogenesis and Host Defense,
Department of Medicine,
Division of Pediatric Immunology/Rheumatology, Department of Pediatrics,
Biomedical Sciences Graduate Program,
Departments of Microbiology and Immunology,
Howard Hughes Medical Institute,
Division of Rheumatology, Department of Medicine, and
Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, San Francisco, California, USA
| | - Armando Lemus
- Program in Microbial Pathogenesis and Host Defense,
Department of Medicine,
Division of Pediatric Immunology/Rheumatology, Department of Pediatrics,
Biomedical Sciences Graduate Program,
Departments of Microbiology and Immunology,
Howard Hughes Medical Institute,
Division of Rheumatology, Department of Medicine, and
Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, San Francisco, California, USA
| | - Arthur Weiss
- Program in Microbial Pathogenesis and Host Defense,
Department of Medicine,
Division of Pediatric Immunology/Rheumatology, Department of Pediatrics,
Biomedical Sciences Graduate Program,
Departments of Microbiology and Immunology,
Howard Hughes Medical Institute,
Division of Rheumatology, Department of Medicine, and
Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, San Francisco, California, USA
| | - Joanne Engel
- Program in Microbial Pathogenesis and Host Defense,
Department of Medicine,
Division of Pediatric Immunology/Rheumatology, Department of Pediatrics,
Biomedical Sciences Graduate Program,
Departments of Microbiology and Immunology,
Howard Hughes Medical Institute,
Division of Rheumatology, Department of Medicine, and
Rosalind Russell Medical Research Center for Arthritis, University of California, San Francisco, San Francisco, California, USA
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31
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Abstract
Luteinizing hormone releasing hormone-Pseudomonas aeruginosa exotoxin A (LHRH-PE40) and sequence-modified LHRH-PE40 (mLHRH-PE40) are two anti-tumour drugs developed by fusing either native or modified LHRH with the same PE40. This study was designed to evaluate their toxicity on the male genital tract. Male rats were treated intravenously or intraperitoneally with either LHRH-PE40 or mLHRH-PE40 on alternate days for 12 weeks. Serum and testes were examined to detect anti-LHRH, anti-LHRH-PE40 or anti-mLHRH-PE40 using an ELISA assay, testosterone level was measured by radioimmunoassay, and testicular morphology was evaluated. Rats receiving LHRH-PE40 intraperitoneal injections had higher anti-LHRH antibody titres, lower serum testosterone concentration and remarkable testicular atrophy, whereas those administrated with intravenous injections of either LHRH-PE40 or mLHRH-PE40 demonstrated no such changes. We concluded that the testicular atrophy can be attributed to higher titre of anti-LHRH antibodies, which was affected by both drug delivery and the LHRH motif of the chimeric protein.
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Affiliation(s)
- Jun Li
- Department of Onco-pathology and the Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou, China
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32
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Abstract
LHRH-PE40, a recombinant DNA-derived protein composed of LHRH and Pseudomonas aeruginosa exotoxin A, is being developed for the treatment of malignant tumours. This experiment was designed to assess its preclinical safety. Reproductive toxicity studies, pharmacokinetic studies, single- and repeat-dose intraperitoneal or intravenous toxicity studies in mice, rats and monkeys were conducted to assess the toxicity of LHRH-PE40. In intravenous single-dose studies in mice, the LD50 was 731.26 microg/kg and 676.03 microg/kg in male and female mice respectively. In single-dose studies and repeat-dose range-finding studies in rats, dose-limited severe vascular leakage syndromes occurred. In repeat-dose long-term studies, except drug-related vascular leakage syndromes, other drug-related changes included decreased testis weight and testis atrophy. In single-dose and repeat-dose studies in monkeys, dose-limited acute tubular necrosis of the kidneys was the chief finding. In reproductive studies, drug-related changes were decreased food intakes, decreased testis weight and uterus weight, decreased foetus weight and increased foetus mortality, increased maternal and F1 offspring mortality and decreased maternal and F1 offspring body weight. Pharmacokinetic studies showed a similar half-time of distribution and clearance in mice and monkeys. Tissue distribution showed a high concentration in the kidneys and a low concentration in the brain. LHRH-PE40 induced vascular leak syndromes in rats and acute tubular necrosis in monkeys. It also led to testicle atrophy in rats and overt productive toxicity to parents and F1 generations in mice. Because of these findings, it should be monitored carefully in human clinical trials for things such as respiratory, urinary and reproductive toxicities.
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Affiliation(s)
- Jun Li
- Department of Oncopathology and the Key Immunopathology Laboratory of Guangdong Province, Shantou University Medical College, Shantou, China.
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Kawakami K, Nakajima O, Morishita R, Nagai R. Targeted anticancer immunotoxins and cytotoxic agents with direct killing moieties. ScientificWorldJournal 2006; 6:781-90. [PMID: 16830050 PMCID: PMC5917189 DOI: 10.1100/tsw.2006.162] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2006] [Revised: 05/04/2006] [Accepted: 06/27/2006] [Indexed: 12/02/2022] Open
Abstract
Despite the progress of the bioinformatics approach to characterize cell-surface antigens and receptors on tumor cells, it remains difficult to generate novel cancer vaccines or neutralizing monoclonal antibody therapeutics. Among targeted cancer therapeutics, biologicals with targetable antibodies or ligands conjugated or fused to toxins or chemicals for direct cell-killing ability have been developed over the last 2 decades. These conjugated or fused chimeric proteins are termed immunotoxins or cytotoxic agents. Two agents, DAB389IL-2 (ONTAKTM) targeting the interleukin-2 receptor and CD33-calicheamicin (Mylotarg), have been approved by the FDA for cutaneous T-cell lymphoma (CTCL) and relapsed acute myeloid leukemia (AML), respectively. Such targetable agents, including RFB4(dsFv)-PE38 (BL22), IL13-PE38QQR, and Tf-CRM107, are being tested in clinical trials. Several agents using unique technology such as a cleavable adapter or immunoliposomes with antibodies are also in the preclinical stage. This review summarizes the generation, mechanism, and development of these agents. In addition, possible future directions of this therapeutic approach are discussed.
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Affiliation(s)
- Koji Kawakami
- Department of Pharmacoepidemiology, Graduate School of Medicine and Public Health, Kyoto University, Yoshida Konoecho, Sakyoku, Kyoto 606-8501, Japan.
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34
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Kannan TR, Baseman JB. ADP-ribosylating and vacuolating cytotoxin of Mycoplasma pneumoniae represents unique virulence determinant among bacterial pathogens. Proc Natl Acad Sci U S A 2006; 103:6724-9. [PMID: 16617115 PMCID: PMC1458948 DOI: 10.1073/pnas.0510644103] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Unlike many bacterial pathogens, Mycoplasma pneumoniae is not known to produce classical toxins, and precisely how M. pneumoniae injures the respiratory epithelium has remained a mystery for >50 years. Here, we report the identification of a virulence factor (MPN372) possibly responsible for airway cellular damage and other sequelae associated with M. pneumoniae infections in humans. We show that M. pneumoniae MPN372 encodes a 68-kDa protein that possesses ADP-ribosyltransferase (ART) activity. Within its N terminus, MPN372 contains key amino acids associated with NAD binding and ADP-ribosylating activity, similar to pertussis toxin (PTX) S1 subunit (PTX-S1). Interestingly, MPN372 ADP ribosylates both identical and distinct mammalian proteins when compared with PTX-S1. Remarkably, MPN372 elicits extensive vacuolization and ultimate cell death of mammalian cells, including distinct and progressive patterns of cytopathology in tracheal rings in organ culture that had been previously ascribed to infection with WT virulent M. pneumoniae. We observed dramatic seroconversion to MPN372 in patients diagnosed with M. pneumoniae-associated pneumonia, indicating that this toxin is synthesized in vivo and possesses highly immunogenic epitopes.
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Affiliation(s)
- T. R. Kannan
- Department of Microbiology and Immunology, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229
| | - Joel B. Baseman
- Department of Microbiology and Immunology, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229
- *To whom correspondence should be addressed. E-mail:
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35
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Andersson Y, Le H, Juell S, Fodstad Ø. AMP-activated protein kinase protects against anti-epidermal growth factor receptor-Pseudomonas exotoxin A immunotoxin-induced MA11 breast cancer cell death. Mol Cancer Ther 2006; 5:1050-9. [PMID: 16648577 DOI: 10.1158/1535-7163.mct-05-0318] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have shown previously that our 425.3PE immunotoxin inhibits protein synthesis and induces apoptosis in human breast cancer cells. In attempts to further elucidate the intracellular pathways implicated in its cellular effects, we found that the immunotoxin induced an initial stress response, which rapidly caused an imbalance in the cellular energy status with an increase in reactive oxygen species. The AMP-activated protein kinase (AMPK), a sensor of increased cellular AMP/ATP ratio, was activated by 425.3PE. An immunotoxin-induced activation of c-Jun NH2-terminal kinase (JNK) preceded and overlapped caspase-mediated cleavage of the alpha-subunit of AMPK in a time- and dose-dependent manner. The JNK activation occurred already at a dose level too low to induce any detectable changes in the apoptotic machinery or protein synthesis. In contrast, cycloheximide, even at a concentration causing a 90% inhibition of protein synthesis, did neither affect the ATP level nor activate JNK and AMPK. Pretreatment of the cells with the specific AMPK inhibitor compound C and JNK inhibitor SP600125 blocked activation of AMPK and JNK, respectively, and subsequently sensitized the cells to 425.3PE-induced cell death. Whereas the antioxidant N-acetyl-l-cysteine blocked the generation of reactive oxygen species and activation of JNK and AMPK, it did not block immunotoxin-induced apoptosis. Together, the results show that 425.3PE induces several parallel signaling events, observed initially as an early activation of survival pathways, protecting the cells against the toxic effects of the immunotoxin, followed by subsequent apoptosis induction and protein synthesis inhibition. Conceivably, therapeutic manipulation of the signaling intermediates AMPK and JNK might provide a means to maximize the anticancer effects of the 425.3 immunotoxin.
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Affiliation(s)
- Yvonne Andersson
- Department of Tumor Biology and Institute for Cancer Research, Norwegian Radium Hospital, 0310 Oslo, Norway.
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36
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Abstract
CONCLUSION Our findings suggest that edaravone can protect against cochlear damage caused by Pseudomonas aeruginosa exotoxin A (PaExoA). OBJECTIVE To analyze the protective effect of a free radical scavenger, edaravone, against the ototoxicity resulting from exposure of the middle ear to PaExoA. MATERIAL AND METHODS In nine groups of albino rats the following solutions were instilled either via the tympanic membrane into the round window niche [intratympanically (i.t.)] or intravenously (i.v.): edaravone (i.v.); edaravone (i.t.); PaExoA (i.t.) + edaravone (i.t.; simultaneously); PaExoA (i.t.) + edaravone (i.t.; 1 h after); PaExoA (i.t.) + edaravone (i.t.; 24 h after); PaExoA (i.t.) + edaravone (i.v.; simultaneously); PaExoA (i.t.) + edaravone (i.v.; 1 h after); PaExoA (i.t.) + edaravone (i.v.; 24 h after); PaExoA (i.t.) + saline (i.v.). Frequency-specific (2-20 kHz) auditory brainstem responses were measured to determine hearing thresholds before and 2, 5 and 10 days after instillation. RESULTS PaExoA had penetrated from the middle ear into the cochlea and caused hearing loss. This impairment was blocked by intratympanic injection of edaravone when given simultaneously or 1 h after the first instillation of PaExoA, or by intravenous injection of edaravone when given simultaneously. There were significant differences in protective effect between the intratympanic and intravenous routes.
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Affiliation(s)
- Masaya Takumida
- Department of Otolaryngology, Faculty of Medicine, Hiroshima University, Minamiku, Hiroshima, Japan.
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37
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Saitoh M, Tanaka K, Nishimori K, Makino SI, Kanno T, Ishihara R, Hatama S, Kitano R, Kishima M, Sameshima T, Akiba M, Nakazawa M, Yokomizo Y, Uchida I. The artAB genes encode a putative ADP-ribosyltransferase toxin homologue associated with Salmonella enterica serovar Typhimurium DT104. Microbiology (Reading) 2005; 151:3089-3096. [PMID: 16151219 DOI: 10.1099/mic.0.27933-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Many bacterial pathogens encode ADP-ribosyltransferase toxins. The authors identified an ADP-ribosyltransferase toxin homologue (ArtA, ArtB) in Salmonella enterica serovar Typhimurium (S. typhimurium) DT104. ArtA is most homologous to a putative pertussis-like toxin subunit present in Salmonella typhi (STY1890) and Salmonella paratyphi A (SPA1609), while ArtB shows homology to a hypothetical periplasmic protein of S. typhi (STY1364) and S. paratyphi A (SPA1188), and a putative pertussis-like toxin subunit in S. typhi (STY1891) and S. paratyphi A (SPA1610). The artA gene was detected from the phage particle fraction upon mitomycin C induction, and the flanking region of artAB contains a prophage-like sequence, suggesting that these putative toxin genes reside within a prophage. Southern blotting analysis revealed that artA is conserved in 12 confirmed DT104 strains and in four related strains which are not phage-typed but are classified into the same group as DT104 by both amplified-fragment length polymorphism and pulsed-field gel electrophoresis. Except for one strain, NCTC 73, all 13 S. typhimurium strains which were classified into different groups from that of DT104 lacked the artA locus. The results suggest that phage-mediated recombination has resulted in the acquisition of art genes in S. typhimurium DT104 strains.
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Affiliation(s)
- Mariko Saitoh
- Nemuro Livestock Hygiene Service Center, Betsukaimidorimachi-69, Betsukai, Notsukegun 086-0214, Japan
- Hokkaido Research Station, National Institute of Animal Health, Hitsujigaoka-4, Toyohira, Sapporo 062-0045, Japan
| | - Kiyoshi Tanaka
- Hokkaido Research Station, National Institute of Animal Health, Hitsujigaoka-4, Toyohira, Sapporo 062-0045, Japan
| | - Kei Nishimori
- Hokkaido Research Station, National Institute of Animal Health, Hitsujigaoka-4, Toyohira, Sapporo 062-0045, Japan
| | - Sou-Ichi Makino
- Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro 080-8555, Japan
| | - Toru Kanno
- Hokkaido Research Station, National Institute of Animal Health, Hitsujigaoka-4, Toyohira, Sapporo 062-0045, Japan
| | - Ryoko Ishihara
- Hokkaido Research Station, National Institute of Animal Health, Hitsujigaoka-4, Toyohira, Sapporo 062-0045, Japan
| | - Shinichi Hatama
- Hokkaido Research Station, National Institute of Animal Health, Hitsujigaoka-4, Toyohira, Sapporo 062-0045, Japan
| | - Rie Kitano
- National Institute of Animal Health, Tsukuba, Ibaraki 305-0856, Japan
| | - Masato Kishima
- National Institute of Animal Health, Tsukuba, Ibaraki 305-0856, Japan
| | - Toshiya Sameshima
- National Institute of Animal Health, Tsukuba, Ibaraki 305-0856, Japan
| | - Masato Akiba
- National Institute of Animal Health, Tsukuba, Ibaraki 305-0856, Japan
| | - Muneo Nakazawa
- National Institute of Animal Health, Tsukuba, Ibaraki 305-0856, Japan
| | - Yuichi Yokomizo
- National Institute of Animal Health, Tsukuba, Ibaraki 305-0856, Japan
| | - Ikuo Uchida
- Hokkaido Research Station, National Institute of Animal Health, Hitsujigaoka-4, Toyohira, Sapporo 062-0045, Japan
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38
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Lee VT, Smith RS, Tümmler B, Lory S. Activities of Pseudomonas aeruginosa effectors secreted by the Type III secretion system in vitro and during infection. Infect Immun 2005; 73:1695-705. [PMID: 15731070 PMCID: PMC1064929 DOI: 10.1128/iai.73.3.1695-1705.2005] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa utilizes a number of distinct pathways to secrete proteins that play various roles during infection. These include the type II secretion system, which is responsible for the secretion of the majority of exoproducts into the surrounding environment, including toxins and degradative enzymes. In contrast, the type III secretion system mediates the delivery of protein effectors directly into the cytoplasm of the host cell. Using tissue culture assays and a mouse acute-pneumonia model, we have determined the contribution of each of the type III effectors during infection. In strain PAK, ExoS is the major cytotoxin required for colonization and dissemination during infection. ExoT confers protection of tissue culture cells from type III-dependent lysis, while ExoY seemed to have little effect on cytotoxicity. ExoU is over 100-fold more cytotoxic than ExoS. The cytotoxicity of type II secretion was determined following deletion of the genes for the more toxic type III secretion system. The participation of these secretion systems during lifelong colonization of cystic fibrosis (CF) patients is unclear. By comparing clonal strains from the same patient isolated at the initial onset of P. aeruginosa infection and more than a decade later, after chronic colonization has been established, we show that initial strains are more cytotoxic than chronic strains that have evolved to reduce type III secretion. Constitutive expression of genes for the type III secretion system restored ExoS secretion but did not always reestablish cytotoxicity, suggesting that CF strains accumulate a number of mutations to reduce bacterial toxicity to the host.
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Affiliation(s)
- Vincent T Lee
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115, USA
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39
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Abstract
Pseudomonas aeruginosa uses a type III secretion system to promote development of severe disease, particularly in patients with impaired immune defenses. While the biochemical and enzymatic functions of ExoU, ExoS, and ExoT, three effector proteins secreted by this system, are well defined, the relative roles of each protein in the pathogenesis of acute infections is not clearly understood. Since ExoU and ExoS are usually not secreted by the same strain, it has been difficult to directly compare the effects of these proteins during infection. In the work described here, several isogenic mutants of a bacterial strain that naturally secretes ExoU, ExoS, and ExoT were generated to carefully evaluate the relative contribution of each effector protein to pathogenesis in a mouse model of acute pneumonia. Measurements of mortality, bacterial persistence in the lung, and dissemination indicated that secretion of ExoU had the greatest impact on virulence while secretion of ExoS had an intermediate effect and ExoT had a minor effect. It is of note that these results conclusively show for the first time that ExoS is a virulence factor. Infection with isogenic mutants secreting wild-type ExoS, ExoS defective in GTPase-activating protein (GAP) activity, or ExoS defective in ADP-ribosyltransferase activity demonstrated that the virulence of ExoS was largely dependent on its ADP-ribosyltransferase activity. The GAP activity of this protein had only a minor effect in vivo. The relative virulence associated with each of these type III effector proteins may have important prognostic implications for patients infected with P. aeruginosa.
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Affiliation(s)
- Ciara M Shaver
- Department of Microbiology, Northwestern University Feinberg School of Medicine, 303 East Chicago Ave., Searle 6-495, Chicago, IL 60611, USA
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40
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Pomorski P, Watson JM, Haskill S, Jacobson KA. How adhesion, migration, and cytoplasmic calcium transients influence interleukin-1beta mRNA stabilization in human monocytes. ACTA ACUST UNITED AC 2004; 57:143-57. [PMID: 14743348 DOI: 10.1002/cm.10159] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We investigated the mechanisms by which primary human monocyte migration and the production of important cytokines are co-regulated. Motile monocytes underwent cyclic morphologic and adhesive changes that were associated with intracellular free calcium changes; in such cells, cytokine transcripts were unstable and translationally repressed. Agents that activate monocytes, including lipopolysacharrides (LPS), cytomegalovirus (CMV), and tumor necrosis factor (TNFalpha), have been shown to de-repress translation and these agents stabilize adhesion-induced transcripts for IL-lbeta and IL-8 and markedly diminish cell migration in the presence of autologous serum. LPS suppressed Rho A activity and either this agent or C3 transferase elevated intracellular free calcium, stabilized transcripts, and, in tandem, inhibited cell migration by preventing tail retraction, a prerequisite for cell translocation. These results, therefore, suggest that monocyte activating agents inhibit the RhoA pathway and continuously elevate intracellular calcium leading to a concomitant decrease in monocyte migration and stabilization of cytokine transcripts prior to translation.
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Affiliation(s)
- P Pomorski
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, 27599, USA
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41
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Benedek O, Nagy G, Emody L. Intracellular signalling and cytoskeletal rearrangement involved in Yersinia pestis plasminogen activator (Pla) mediated HeLa cell invasion. Microb Pathog 2004; 37:47-54. [PMID: 15194160 DOI: 10.1016/j.micpath.2004.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2003] [Revised: 03/30/2004] [Accepted: 04/01/2004] [Indexed: 10/26/2022]
Abstract
Yersinia pestis, the etiologic agent of plague is a highly invasive organism being able to invade non-phagocytic epithelial cells. Its plasminogen activator (Pla), encoded by the pPCP1 plasmid plays a pivotal role in internalisation of bacteria by HeLa cells. The aim of this study was to analyse the intracellular signalling processes and cytoskeletal rearrangement events associated with invasion. Wortmannin caused a 50% decrease of invasiveness at 50nM concentration pointing to the involvement of phosphatidyl-inosinol-4 kinase (PtINs4). Pre-treatment with staurosporin, a potent inhibitor of protein kinases (PKs) and with genistein, a specific tyrosine kinase inhibitor decreased the number of internalised bacteria about seven-fold and two-fold, respectively, indicating the involvement of PKs including tyrosine kinases in Pla-mediated internalisation. Cytochalasin D, an actin polymerisation inhibitor, C3 exoenzyme of Clostridium botulinum, a specific inhibitor of small GTPase Rho, and NDGA, a 5-lipoxygenase inhibitor also involved in Rho activation strongly reduced the number of internalised bacteria revealing the role of cytoskeletal events in the invasion process. All the tested inhibitors changed the invasion but not the adhesion pattern of the Pla producing recombinant strain. Actin rearrangement could also be visualised also with rhodamin-phalloidin staining.
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Affiliation(s)
- Orsolya Benedek
- Department of Medical Microbiology and Immunology, Faculty of Medicine, University of Pécs, Szigeti út 12., H-7624 Pécs, Hungary
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42
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Nagahama M, Yamaguchi A, Hagiyama T, Ohkubo N, Kobayashi K, Sakurai J. Binding and internalization of Clostridium perfringens iota-toxin in lipid rafts. Infect Immun 2004; 72:3267-75. [PMID: 15155629 PMCID: PMC415663 DOI: 10.1128/iai.72.6.3267-3275.2004] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium perfringens iota-toxin is a binary toxin composed of an enzymatic component (Ia) and a binding component (Ib). The oligomer of Ib formed in membranes induces endocytosis. We examined the binding and internalization of Ib by using Cy3-labeled Ib. Labeled Ib was retained at the membranes of MDCK cells for 60 min of incubation at 37 degrees C, and later it was detected in cytoplasmic vesicles. To determine whether Ib associates with lipid rafts, we incubated MDCK cells with Ib at 4 or 37 degrees C and fractionated the Triton-insoluble membranes. An Ib complex of 500 kDa was localized at 37 degrees C to the insoluble fractions that fulfilled the criteria of lipid rafts, but it did not form at 4 degrees C. The amount of complex in the raft fraction reached a maximum after 60 min of incubation at 37 degrees C. When the cells that were preincubated with Ib at 4 degrees C were incubated at 37 degrees C, the complex was detected in the raft fraction. The treatment of MDCK cells with methyl-beta-cyclodextrin reduced the localization of the Ib complex to the rafts and the rounding of the cells induced by Ia plus Ib. When 125I-labeled Ia was incubated with the cells in the presence of Ib at 37 degrees C, it was localized in the raft fraction. Surface plasmon resonance analysis revealed that Ia binds to the oligomer of Ib. We conclude that Ib binds to a receptor in membranes and then moves to rafts and that Ia bound to the oligomer of Ib formed in the rafts is internalized.
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Affiliation(s)
- Masahiro Nagahama
- Department of Microbiology, Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro, Tokushima 770-8514, Japan
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Abstract
The heat shock protein Hsp90 is essential for uptake of the binary actin ADP-ribosylating toxins Clostridium perfringens iota-toxin and Clostridium difficile transferase into eukaryotic cells. Inhibition of Hsp90 by its specific inhibitor radicicol delayed intoxication of Vero cells by these toxins. A common Hsp90-dependent mechanism for their translocation is discussed.
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Affiliation(s)
- Gerd Haug
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Albert-Ludwigs-Universität Freiburg, D-79104 Freiburg, Germany
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Hale ML, Marvaud JC, Popoff MR, Stiles BG. Detergent-resistant membrane microdomains facilitate Ib oligomer formation and biological activity of Clostridium perfringens iota-toxin. Infect Immun 2004; 72:2186-93. [PMID: 15039342 PMCID: PMC375178 DOI: 10.1128/iai.72.4.2186-2193.2004] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Clostridium perfringens iota-toxin consists of two separate proteins identified as a cell binding protein, iota b (Ib), which forms high-molecular-weight complexes on cells generating Na(+)/K(+)-permeable pores through which iota a (Ia), an ADP-ribosyltransferase, presumably enters the cytosol. Identity of the cell receptor and membrane domains involved in Ib binding, oligomer formation, and internalization is currently unknown. In this study, Vero (toxin-sensitive) and MRC-5 (toxin-resistant) cells were incubated with Ib, after which detergent-resistant membrane microdomains (DRMs) were extracted with cold Triton X-100. Western blotting revealed that Ib oligomers localized in DRMs extracted from Vero, but not MRC-5, cells while monomeric Ib was detected in the detergent-soluble fractions of both cell types. The Ib protoxin, previously shown to bind Vero cells but not form oligomers or induce cytotoxicity, was detected only in the soluble fractions. Vero cells pretreated with phosphatidylinositol-specific phospholipase C before addition of Ib indicated that glycosylphosphatidyl inositol-anchored proteins were minimally involved in Ib binding or oligomer formation. While pretreatment of Vero cells with filipin (which sequesters cholesterol) had no effect, methyl-beta-cyclodextrin (which extracts cholesterol) reduced Ib binding and oligomer formation and delayed iota-toxin cytotoxicity. These studies showed that iota-toxin exploits DRMs for oligomer formation to intoxicate cells.
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Affiliation(s)
- Martha L Hale
- Toxinology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Maryland 21702-5011, USA.
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Mühlen KA, Schümann J, Wittke F, Stenger S, Van Rooijen N, Van Kaer L, Tiegs G. NK cells, but not NKT cells, are involved in Pseudomonas aeruginosa exotoxin A-induced hepatotoxicity in mice. J Immunol 2004; 172:3034-41. [PMID: 14978108 DOI: 10.4049/jimmunol.172.5.3034] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pseudomonas aeruginosa exotoxin A (PEA) causes T cell- and Kupffer cell (KC)-dependent liver injury in mice. TNF-alpha as well as IL-18 and perforin are important mediators of liver damage following PEA injection. In this study, we focus on the role of NK and NKT cells in PEA-induced liver toxicity. Depletion of both NK and NKT cells by injection of anti-NK1.1 Ab as well as depletion of NK cells alone by anti-asialo GM1 Ab protected mice from PEA-induced hepatotoxicity, whereas mice lacking only NKT cells were susceptible. Additionally, we observed infiltration of NK cells, T cells, and neutrophils into liver parenchyma after injection of PEA. The number of NKT cells, however, remained unchanged. The increase in intrahepatic NK cells depended on KCs and the TNF-alpha-dependent up-regulation of the adhesion molecule VCAM-1 in the liver, but not on NKT cells. PEA also augmented the cytotoxicity of hepatic NK cells against typical NK target cells (YAC-1 cells). This effect depended on KCs, but not on TNF-alpha or NKT cells. Furthermore, only weak expression of MHC class I was detected on hepatocytes, which was further down-regulated in PEA-treated mice. This could explain the susceptibility of hepatocytes to NK cell cytolytic activity in this model. Our results demonstrate that NK cells, activated and recruited independently of NKT cells, contribute to PEA-induced T cell-dependent liver injury in mice.
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Affiliation(s)
- Katrin A Mühlen
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nürnberg, Erlangen, Germany
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Stenqvist M, Anniko M. Additive effects of toxin exposure and destruction of semicircular canal on cochlear function: an auditory brainstem response study in the rat. Acta Otolaryngol 2004; 124:13-8. [PMID: 14977071 DOI: 10.1080/00016480310000764a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVE To ascertain whether the severity of toxin-related hearing loss and the interval between instillation of toxin and surgical trauma affect hearing recovery capacity following semicircular canal (SCC) surgery in the rat. MATERIAL AND METHODS Twelve rats were injected with Pseudomonas aeruginosa exotoxin A (PaExoA). Auditory brainstem responses (ABRs) were measured 72 h and 3 weeks later. Depending on the severity of hearing loss, the rats were divided into two groups: those with moderate (Group A; n = 6) and severe (Group B; n = 6) hearing loss. Three rats from Group A were then operated on 3 weeks after toxin exposure and the other three 3 months after instillation of toxin. All Group B rats were operated on after 3 months. RESULTS In Group A, post-surgical hearing loss recovered to a varying degree but rats in Group B showed little or no hearing recovery capacity. This difference was statistically significant. When the six rats with moderately toxin-affected ears were compared, statistical differences in recovery capacity between those operated on at 3 weeks and at 3 months were also detected. The group with a shorter interval showed significantly less hearing recovery of inner ear function following surgical trauma. CONCLUSION When the toxin causes severe hearing damage there is no capacity for cochlear recovery following additional surgical trauma. When the rat inner ear is moderately affected by PaExoA, the interval between toxin exposure and SCC destruction plays a significant role in the ultimate hearing outcome. Cochlear recovery potential seems to be weakened in close temporal proximity to toxin exposure, but recovers with the passage of time.
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Affiliation(s)
- Monika Stenqvist
- Department of Otolaryngology and Head & Neck Surgery, University Hospital (Akademiska Sjukhuset), Uppsala, Sweden.
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Garrity-Ryan L, Shafikhani S, Balachandran P, Nguyen L, Oza J, Jakobsen T, Sargent J, Fang X, Cordwell S, Matthay MA, Engel JN. The ADP ribosyltransferase domain of Pseudomonas aeruginosa ExoT contributes to its biological activities. Infect Immun 2004; 72:546-58. [PMID: 14688136 PMCID: PMC343945 DOI: 10.1128/iai.72.1.546-558.2004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2003] [Revised: 04/03/2003] [Accepted: 09/22/2003] [Indexed: 11/20/2022] Open
Abstract
ExoT is a type III secreted effector protein found in almost all strains of Pseudomonas aeruginosa and is required for full virulence in an animal model of acute pneumonia. It is comprised of an N-terminal domain with GTPase activating protein (GAP) activity towards Rho family GTPases and a C-terminal ADP ribosyltransferase (ADPRT) domain with minimal activity towards a synthetic substrate in vitro. Consistent with its activity as a Rho family GTPase, ExoT has been shown to inhibit P. aeruginosa internalization into epithelial cells and macrophages, disrupt the actin cytoskeleton through a Rho-dependent pathway, and inhibit wound repair in a scrape model of injured epithelium. We have previously shown that mutation of the invariant arginine of the GAP domain to lysine (R149K) results in complete loss of GAP activity in vitro but only partially inhibits ExoT anti-internalization and cell rounding activity. We have constructed in-frame deletions and point mutations within the ADPRT domain in order to test whether this domain might account for the residual activity observed in ExoT GAP mutants. Deletion of a majority of the ADPRT domain (residues 234 to 438) or point mutations of the ADPRT catalytic site (residues 383 to 385) led to distinct changes in host cell morphology and substantially reduced the ability of ExoT to inhibit in vitro epithelial wound healing over a 24-h period. In contrast, only subtle effects on the efficiency of ExoT-induced bacterial internalization were observed in the ADPRT mutant forms. Expression of each domain individually in Saccharomyces cerevisiae was toxic, whereas expression of each of the catalytically inactive mutant domains was not. Collectively, these data demonstrate that the ADPRT domain of ExoT is active in vivo and contributes to the pathogenesis of P. aeruginosa infections.
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Affiliation(s)
- L Garrity-Ryan
- Departments of Medicine, University of California, San Francisco, San Francisco, California 94143, USA
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48
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Abstract
Pseudomonas aeruginosa exoenzyme S (ExoS) is a type III secretion (TTS) effector, which includes both a GTPase-activating protein (GAP) activity toward the Rho family of low-molecular-weight G (LMWG) proteins and an ADP-ribosyltransferase (ADPRT) activity that targets LMWG proteins in the Ras, Rab, and Rho families. The coordinate function of both activities of ExoS in J774A.1 macrophages was assessed by using P. aeruginosa strains expressing and translocating wild-type ExoS or ExoS defective in GAP and/or ADPRT activity. Distinct and coordinated functions were identified for both domains. The GAP activity was required for the antiphagocytic effect of ExoS and was linked to interference of lamellopodium and membrane ruffle formation. Alternatively, the ADPRT activity of ExoS altered cellular adherence and morphology and was linked to effects on filopodium formation. The cellular mechanism of ExoS GAP activity included an inactivation of Rac1 function, as determined in p21-activated kinase 1-glutathione S-transferase (GST) pull-down assays. The ADPRT activity of ExoS targeted Ras and RalA but not Rab or Rho proteins, and Ral binding protein 1-GST pull-down assays identified an effect of ExoS ADPRT activity on RalA activation. The results from these studies confirm the bifunctional nature of ExoS activity within macrophages when translocated by TTS.
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Affiliation(s)
- Claudia L Rocha
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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49
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Abstract
C3-like ADP-ribosyltransferases represent an expanding family of related exoenzymes, which are produced by Clostridia and various Staphylococcus aureus strains. Here we report on the cloning and biochemical characterization of an ADP-ribosyltransferase from Bacillus cereus strain 2339. The transferase encompasses 219 amino acids; it has a predicted mass of 25.2 kDa and a theoretical isoelectric point of 9.3. To indicate the relationship to the family of C3-like ADP-ribosyltransferases, we termed the enzyme C3cer. The amino acid sequence of C3cer is 30 to 40% identical to other C3-like exoenzymes. By site-directed mutagenesis, Arg(59), Arg(97), Tyr(151), Arg(155), Thr(178), Tyr(180), Gln(183), and Glu(185) of recombinant C3cer were identified as pivotal residues of enzyme activity and/or protein substrate recognition. Precipitation experiments with immobilized RhoA revealed that C3cerTyr(180), which is located in the so-called "ADP-ribosylating toxin turn-turn" (ARTT) motif, plays a major role in the recognition of RhoA. Like other C3-like exoenzymes, C3cer ADP-ribosylates preferentially RhoA and RhoB and to a much lesser extent RhoC. Because the cellular accessibility of recombinant C3cer is low, a fusion toxin (C2IN-C3cer), consisting of the N-terminal 225 amino acid residues of the enzyme component of C2 toxin from Clostridium botulinum and C3cer was used to study the cytotoxic effects of the transferase. This fusion toxin caused rounding up of Vero cells comparable to the effects of Rho-inactivating toxins.
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Affiliation(s)
- Christian Wilde
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie der Universität Freiburg, Otto-Krayer-Haus, Albertstrasse 25, D-79104 Freiburg, Germany
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Maeta M, Anniko M. Protective effect of brain-derived neurotrophic factor against the ototoxicity of Pseudomonas aeruginosa exotoxin A. Acta Otolaryngol 2003; 123:14-9. [PMID: 12625567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
OBJECTIVE The protective effect of brain-derived neurotrophic factor (BDNF) against the ototoxicity resulting from exposure of Pseudomonas aeruginosa exotoxin A (PaExoA) to the middle ear was analyzed. The combined effect of BDNF and N(G)-nitro-L-arginine methyl ester (L-NAME) was also investigated. MATERIAL AND METHODS Six groups of albino rats were instilled through the tympanic membrane into the round window niche with the following solutions: saline; PaExoA; BDNF; L-NAME; PaExoA + BDNF; and PaExoA + BDNF + L-NAME. Frequency-specific (2-31.5 kHz) auditory brainstem responses were used to obtain the hearing thresholds before and 2, 5 and 15 days after instillation. RESULTS PaExoA penetrated from the middle ear into the cochlea, causing initially mixed hearing loss, followed by persistent sensorineural hearing loss. This impairment was blocked by BDNF at 6, 8 and 10 kHz on Day 2 and at 8 kHz on Day 5. L-NAME given in combination with BDNF did not show any additional protective effect. There were no significant differences in the thickness of the round window membrane between control ears and those in each instillation group. CONCLUSION Our results suggest that BDNF may protect against cochlear damage caused by PaExoA in the middle turns of the ear.
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Affiliation(s)
- Manabu Maeta
- Department of Otorhinolaryngology and Head & Neck Surgery, Uppsala University Hospital, Uppsala, Sweden.
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