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Yang NJ, Neel DV, Deng L, Heyang M, Kennedy-Curran A, Tong VS, Park JM, Chiu IM. Nociceptive Sensory Neurons Mediate Inflammation Induced by Bacillus Anthracis Edema Toxin. Front Immunol 2021; 12:642373. [PMID: 34413846 PMCID: PMC8369925 DOI: 10.3389/fimmu.2021.642373] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 12/15/2020] [Accepted: 07/19/2021] [Indexed: 01/03/2023] Open
Abstract
Bacterial products are able to act on nociceptive neurons during pathogenic infection. Neurogenic inflammation is an active part of pain signaling and has recently been shown to impact host-pathogen defense. Bacillus anthracis Edema Toxin (ET) produces striking edema in peripheral tissues, but the cellular mechanisms involved in tissue swelling are not completely understood. Here, we find that nociceptive neurons play a role in ET-induced edema and inflammation in mice. Subcutaneous footpad infection of B. anthracis Sterne caused ET-dependent local mechanical allodynia, paw swelling and body weight gain. Subcutaneous administration of ET induced paw swelling and vascular leakage, the early phases of which were attenuated in the absence of Trpv1+ or Nav1.8+ nociceptive neurons. Nociceptive neurons express the anthrax toxin receptor ANTXR2, but this did not mediate ET-induced edema. ET induced local cytokine expression and neutrophil recruitment, which were dependent in part on Trpv1+ nociceptive neurons. Ablation of Trpv1+ or Nav1.8+ nociceptive neurons also attenuated early increases in paw swelling and body weight gain during live B. anthracis infection. Our findings indicate that nociceptive neurons play an active role in inflammation caused by B. anthracis and Edema Toxin to potentially influence bacterial pathogenesis.
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Affiliation(s)
- Nicole J. Yang
- Department of Immunology, Harvard Medical School, Boston, MA, United States
| | - Dylan V. Neel
- Department of Immunology, Harvard Medical School, Boston, MA, United States
| | - Liwen Deng
- Department of Immunology, Harvard Medical School, Boston, MA, United States
| | - Michelle Heyang
- Department of Immunology, Harvard Medical School, Boston, MA, United States
| | | | - Victoria S. Tong
- Department of Immunology, Harvard Medical School, Boston, MA, United States
| | - Jin Mo Park
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, United States
| | - Isaac M. Chiu
- Department of Immunology, Harvard Medical School, Boston, MA, United States
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2
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Cui X, Wang J, Li Y, Couse ZG, Risoleo TF, Moayeri M, Leppla SH, Malide D, Yu ZX, Eichacker PQ. Bacillus anthracis edema toxin inhibits hypoxic pulmonary vasoconstriction via edema factor and cAMP-mediated mechanisms in isolated perfused rat lungs. Am J Physiol Heart Circ Physiol 2021; 320:H36-H51. [PMID: 33064559 PMCID: PMC7847081 DOI: 10.1152/ajpheart.00362.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 10/15/2020] [Accepted: 10/15/2020] [Indexed: 12/31/2022]
Abstract
Bacillus anthracis edema toxin (ET) inhibited lethal toxin-stimulated pulmonary artery pressure (Ppa) and increased lung cAMP levels in our previous study. We therefore examined whether ET inhibits hypoxic pulmonary vasoconstriction (HPV). Following baseline hypoxic measures in isolated perfused lungs from healthy rats, compared with diluent, ET perfusion reduced maximal Ppa increases (mean ± SE percentage of maximal Ppa increase with baseline hypoxia) during 6-min hypoxic periods (FIO2 = 0%) at 120 min (16 ± 6% vs. 51 ± 6%, P = 0.004) and 180 min (11.4% vs. 55 ± 6%, P = 0.01). Protective antigen-mAb (PA-mAb) and adefovir inhibit host cell edema factor uptake and cAMP production, respectively. In lungs perfused with ET following baseline measures, compared with placebo, PA-mAb treatment increased Ppa during hypoxia at 120 and 180 min (56 ± 6% vs. 10 ± 4% and 72 ± 12% vs. 12 ± 3%, respectively, P ≤ 0.01) as did adefovir (84 ± 10% vs. 16.8% and 123 ± 21% vs. 26 ± 11%, respectively, P ≤ 0.01). Compared with diluent, lung perfusion with ET for 180 min reduced the slope of the relationships between Ppa and increasing concentrations of endothelin-1 (ET-1) (21.12 ± 2.96 vs. 3.00 ± 0.76 × 108 cmH2O/M, P < 0.0001) and U46619, a thromboxane A2 analogue (7.15 ± 1.01 vs. 3.74 ± 0.31 × 107 cmH2O/M, P = 0.05) added to perfusate. In lungs isolated from rats after 15 h of in vivo infusions with either diluent, ET alone, or ET with PA-mAb, compared with diluent, the maximal Ppa during hypoxia and the slope of the relationship between change in Ppa and ET-1 concentration added to the perfusate were reduced in lungs from animals challenged with ET alone (P ≤ 0.004) but not with ET and PA-mAb together (P ≥ 0.73). Inhibition of HPV by ET could aggravate hypoxia during anthrax pulmonary infection.NEW & NOTEWORTHY The most important findings here are edema toxin's potent adenyl cyclase activity can interfere with hypoxic pulmonary vasoconstriction, an action that could worsen hypoxemia during invasive anthrax infection with lung involvement. These findings, coupled with other studies showing that lethal toxin can disrupt pulmonary vascular integrity, indicate that both toxins can contribute to pulmonary pathophysiology during infection. In combination, these investigations provide a further basis for the use of antitoxin therapies in patients with worsening invasive anthrax disease.
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Affiliation(s)
- Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jeffrey Wang
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Zoe G Couse
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Thomas F Risoleo
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
| | - Daniela Malide
- National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Zu-Xi Yu
- National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Peter Q Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
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3
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Greaney AJ, Portley MK, O’Mard D, Crown D, Maier NK, Mendenhall MA, Mayer-Barber KD, Leppla SH, Moayeri M. Frontline Science: Anthrax lethal toxin-induced, NLRP1-mediated IL-1β release is a neutrophil and PAD4-dependent event. J Leukoc Biol 2020; 108:773-786. [PMID: 32421904 PMCID: PMC11062252 DOI: 10.1002/jlb.4hi0320-028r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [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: 01/10/2020] [Revised: 03/17/2020] [Accepted: 03/28/2020] [Indexed: 12/21/2022] Open
Abstract
Anthrax lethal toxin (LT) is a protease that activates the NLRP1b inflammasome sensor in certain rodent strains. Unlike better-studied sensors, relatively little is known about the priming requirements for NLRP1b. In this study, we investigate the rapid and striking priming-independent LT-induced release of IL-1β in mice within hours of toxin challenge. We find IL-1β release to be a NLRP1b- and caspase-1-dependent, NLRP3 and caspase-11-independent event that requires both neutrophils and peptidyl arginine deiminiase-4 (PAD4) activity. The simultaneous LT-induced IL-18 response is neutrophil-independent. Bone marrow reconstitution experiments in mice show toxin-induced IL-1β originates from hematopoietic cells. LT treatment of neutrophils in vitro did not induce IL-1β, neutrophil extracellular traps (NETs), or pyroptosis. Although platelets interact closely with neutrophils and are also a potential source of IL-1β, they were unable to bind or endocytose LT and did not secrete IL-1β in response to the toxin. LT-treated mice had higher levels of cell-free DNA and HMGB1 in circulation than PBS-treated controls, and treatment of mice with recombinant DNase reduced the neutrophil- and NLRP1-dependent IL-1β release. DNA sensor AIM2 deficiency, however, did not impact IL-1β release. These data, in combination with the findings on PAD4, suggest a possible role for in vivo NETs or cell-free DNA in cytokine induction in response to LT challenge. Our findings suggest a complex interaction of events and/or mediators in LT-treated mice with the neutrophil as a central player in induction of a profound and rapid inflammatory response to toxin.
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MESH Headings
- Adaptor Proteins, Signal Transducing/deficiency
- Adaptor Proteins, Signal Transducing/physiology
- Animals
- Anthrax/immunology
- Antigens, Bacterial/pharmacology
- Antigens, Bacterial/toxicity
- Apoptosis Regulatory Proteins/deficiency
- Apoptosis Regulatory Proteins/physiology
- Bacillus anthracis/pathogenicity
- Bacillus anthracis/physiology
- Bacterial Toxins/pharmacology
- Bacterial Toxins/toxicity
- Extracellular Traps/physiology
- Inflammasomes/physiology
- Interleukin-1beta/metabolism
- Mice
- Mice, 129 Strain
- Mice, Congenic
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, SCID
- Monocytes/drug effects
- Monocytes/physiology
- NLR Family, Pyrin Domain-Containing 3 Protein/deficiency
- Neutrophils/drug effects
- Neutrophils/metabolism
- Protein-Arginine Deiminase Type 4/deficiency
- Protein-Arginine Deiminase Type 4/physiology
- Pyroptosis/drug effects
- Radiation Chimera
- Species Specificity
- Spores, Bacterial
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Affiliation(s)
- Allison J. Greaney
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Makayla K. Portley
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Danielle O’Mard
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Devorah Crown
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Nolan K. Maier
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Megan A. Mendenhall
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Katrin D. Mayer-Barber
- Inflammation and Innate Immunity Unit, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen H. Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Patel VI, Booth JL, Dozmorov M, Brown BR, Metcalf JP. Anthrax Edema and Lethal Toxins Differentially Target Human Lung and Blood Phagocytes. Toxins (Basel) 2020; 12:toxins12070464. [PMID: 32698436 PMCID: PMC7405021 DOI: 10.3390/toxins12070464] [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: 06/29/2020] [Revised: 07/14/2020] [Accepted: 07/15/2020] [Indexed: 12/26/2022] Open
Abstract
Bacillus anthracis, the causative agent of inhalation anthrax, is a serious concern as a bioterrorism weapon. The vegetative form produces two exotoxins: Lethal toxin (LT) and edema toxin (ET). We recently characterized and compared six human airway and alveolar-resident phagocyte (AARP) subsets at the transcriptional and functional levels. In this study, we examined the effects of LT and ET on these subsets and human leukocytes. AARPs and leukocytes do not express high levels of the toxin receptors, tumor endothelium marker-8 (TEM8) and capillary morphogenesis protein-2 (CMG2). Less than 20% expressed surface TEM8, while less than 15% expressed CMG2. All cell types bound or internalized protective antigen, the common component of the two toxins, in a dose-dependent manner. Most protective antigen was likely internalized via macropinocytosis. Cells were not sensitive to LT-induced apoptosis or necrosis at concentrations up to 1000 ng/mL. However, toxin exposure inhibited B. anthracis spore internalization. This inhibition was driven primarily by ET in AARPs and LT in leukocytes. These results support a model of inhalation anthrax in which spores germinate and produce toxins. ET inhibits pathogen phagocytosis by AARPs, allowing alveolar escape. In late-stage disease, LT inhibits phagocytosis by leukocytes, allowing bacterial replication in the bloodstream.
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Affiliation(s)
- Vineet I. Patel
- Department of Medicine, Pulmonary, Critical Care & Sleep Medicine, the University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (V.I.P.); (J.L.B.); (B.R.B.)
| | - J. Leland Booth
- Department of Medicine, Pulmonary, Critical Care & Sleep Medicine, the University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (V.I.P.); (J.L.B.); (B.R.B.)
| | - Mikhail Dozmorov
- Department of Biostatistics, Virginia Commonwealth University, Richmond, VA 23298, USA;
| | - Brent R. Brown
- Department of Medicine, Pulmonary, Critical Care & Sleep Medicine, the University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (V.I.P.); (J.L.B.); (B.R.B.)
| | - Jordan P. Metcalf
- Department of Medicine, Pulmonary, Critical Care & Sleep Medicine, the University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA; (V.I.P.); (J.L.B.); (B.R.B.)
- Department of Microbiology and Immunology, the University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- Veterans Affairs Medical Center, Oklahoma City, OK 73104, USA
- Correspondence:
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5
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Wang J, Yang D, Shen X, Wang J, Liu X, Lin J, Zhong J, Zhao Y, Qi Z. BPTES inhibits anthrax lethal toxin-induced inflammatory response. Int Immunopharmacol 2020; 85:106664. [PMID: 32521490 DOI: 10.1016/j.intimp.2020.106664] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/01/2020] [Accepted: 06/02/2020] [Indexed: 11/17/2022]
Abstract
Bacillus anthracis is a lethal agent of anthrax disease and the toxins are required in anthrax pathogenesis. The anthrax lethal toxin can trigger NLRP1b inflammasome activation and pyroptosis. Although the underlying mechanism is well understood, the medications targeting the NLRP1b inflammasome are not available in the clinic. Herein, we describe that BPTES, a known Glutaminase (GLS) inhibitor, is an effective NLRP1b inflammasome inhibitor. BPTES could effectively and specifically suppress NLRP1b inflammasome activation in macrophages but have no effects on NLRP3, NLRC4 and AIM2 inflammasome activation. Mechanistically, BPTES alleviated the UBR2 mediated proteasomal degradation pathway of the NLRP1b N terminus, thus blocking the release of the CARD domain for subsequent caspase-1 processing. Furthermore, BPTES could prevent disease progression in mice challenged with the anthrax lethal toxin. Taken together, our studies indicate that BPTES can be a promising pharmacological inhibitor to treat anthrax lethal toxin-related inflammatory diseases.
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Affiliation(s)
- Jinling Wang
- Department of Emergency, Zhongshan Hospital of Xiamen University, Xiamen 361005, China
| | - Daowei Yang
- Department of Emergency, Zhongshan Hospital of Xiamen University, Xiamen 361005, China.
| | - Xizi Shen
- Faculty of Medicine, The University of Queensland, Brisbane, Australia
| | - Junsheng Wang
- Department of Emergency, Zhongshan Hospital of Xiamen University, Xiamen 361005, China
| | - Xiaomei Liu
- Department of Emergency, Zhongshan Hospital of Xiamen University, Xiamen 361005, China
| | - Jinzhou Lin
- Department of Emergency, Zhongshan Hospital of Xiamen University, Xiamen 361005, China
| | - Jiaying Zhong
- Faculty of Medicine, Xiamen University, Xiamen, China
| | - Yilin Zhao
- Department of Oncology and Vascular Interventional Radiology, Zhongshan Hospital of Xiamen University, Xiamen, China
| | - Zhongquan Qi
- School of Medicine, Guangxi University, Nanning 530004, China.
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6
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Hasan S, Rahman WU, Sebo P, Osicka R. Distinct Spatiotemporal Distribution of Bacterial Toxin-Produced Cellular cAMP Differentially Inhibits Opsonophagocytic Signaling. Toxins (Basel) 2019; 11:toxins11060362. [PMID: 31226835 PMCID: PMC6628411 DOI: 10.3390/toxins11060362] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 06/12/2019] [Accepted: 06/18/2019] [Indexed: 01/09/2023] Open
Abstract
Myeloid phagocytes have evolved to rapidly recognize invading pathogens and clear them through opsonophagocytic killing. The adenylate cyclase toxin (CyaA) of Bordetella pertussis and the edema toxin (ET) of Bacillus anthracis are both calmodulin-activated toxins with adenylyl cyclase activity that invade host cells and massively increase the cellular concentrations of a key second messenger molecule, 3',5'-cyclic adenosine monophosphate (cAMP). However, the two toxins differ in the kinetics and mode of cell entry and generate different cAMP concentration gradients within the cell. While CyaA rapidly penetrates cells directly across their plasma membrane, the cellular entry of ET depends on receptor-mediated endocytosis and translocation of the enzymatic subunit across the endosomal membrane. We show that CyaA-generated membrane-proximal cAMP gradient strongly inhibits the activation and phosphorylation of Syk, Vav, and Pyk2, thus inhibiting opsonophagocytosis. By contrast, at similar overall cellular cAMP levels, the ET-generated perinuclear cAMP gradient poorly inhibits the activation and phosphorylation of these signaling proteins. Hence, differences in spatiotemporal distribution of cAMP produced by the two adenylyl cyclase toxins differentially affect the opsonophagocytic signaling in myeloid phagocytes.
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Affiliation(s)
- Shakir Hasan
- Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20 Prague, Czech Republic.
| | - Waheed Ur Rahman
- Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20 Prague, Czech Republic.
| | - Peter Sebo
- Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20 Prague, Czech Republic.
| | - Radim Osicka
- Institute of Microbiology of the CAS, v. v. i., Videnska 1083, 142 20 Prague, Czech Republic.
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7
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Zhang D, Liu W, Wen Z, Li B, Liu S, Li J, Chen W. Establishment of a New Zealand White Rabbit Model for Lethal Toxin (LT) Challenge and Efficacy of Monoclonal Antibody 5E11 in the LT-Challenged Rabbit Model. Toxins (Basel) 2018; 10:E289. [PMID: 30002351 PMCID: PMC6071005 DOI: 10.3390/toxins10070289] [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: 06/15/2018] [Accepted: 07/09/2018] [Indexed: 12/23/2022] Open
Abstract
Anthrax caused by Bacillus anthracis is a lethal infectious disease, especially when inhaled, and the mortality rate approaches 100% without treatment. The anthrax antitoxin monoclonal antibody (MAb) 5E11 is a humanized antibody that targets the anthrax protective antigen (PA). The efficacy of 5E11 needs proper animal models. However, anthrax spores are extremely dangerous, so experiments must be conducted under Biosafety Level 3 conditions. Considering the critical effects of lethal toxin (LT) on hosts during infection, we report the establishment of a LT-challenged rabbit model, which caused 100% mortality with a dose of 2 mg PA + 1 mg LF, while a 4 mg PA + 2 mg LF challenge could limit death to within three days. Then, we evaluated 5E11 efficacy against LT. A prophylactic study showed that the i.v. administration of 40 mg/kg 5E11 four days before lethal dose LT challenge could lead to 100% survival. In therapeutic studies, the i.v. administration of 40 mg/kg 5E11 10 min after lethal dose LT challenge could provide complete protection. Overall, we developed a new LT-challenged rabbit model, and our results indicate that 5E11 shows potential for the clinical application in anthrax treatment.
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Affiliation(s)
- Duanyang Zhang
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, China.
| | - Weicen Liu
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, China.
| | - Zhonghua Wen
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, China.
| | - Bing Li
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, China.
| | - Shuling Liu
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, China.
| | - Jianmin Li
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, China.
| | - Wei Chen
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, China.
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8
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Suffredini DA, Cui X, Xu W, Li Y, Eichacker PQ. The Potential Pathogenic Contributions of Endothelial Barrier and Arterial Contractile Dysfunction to Shock Due to B. anthracis Lethal and Edema Toxins. Toxins (Basel) 2017; 9:toxins9120394. [PMID: 29210983 PMCID: PMC5744114 DOI: 10.3390/toxins9120394] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [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: 11/01/2017] [Revised: 11/24/2017] [Accepted: 11/29/2017] [Indexed: 01/22/2023] Open
Abstract
Shock with B. anthracis infection is particularly resistant to conventional cardiovascular support and its mortality rate appears higher than with more common bacterial pathogens. As opposed to many bacteria that lack exotoxins directly depressing hemodynamic function, lethal and edema toxin (LT and ET respectively) both cause shock and likely contribute to the high lethality rate with B. anthracis. Selective inhibition of the toxins is protective in infection models, and administration of either toxin alone in animals produces hypotension with accompanying organ injury and lethality. Shock during infection is typically due to one of two mechanisms: (i) intravascular volume depletion related to disruption of endothelial barrier function; and (ii) extravasation of fluid and/or maladaptive dilation of peripheral resistance arteries. Although some data suggests that LT can produce myocardial dysfunction, growing evidence demonstrates that it may also interfere with endothelial integrity thereby contributing to the extravasation of fluid that helps characterize severe B. anthracis infection. Edema toxin, on the other hand, while known to produce localized tissue edema when injected subcutaneously, has potent vascular relaxant effects that could lead to pathologic arterial dilation. This review will examine recent data supporting a role for these two pathophysiologic mechanisms underlying the shock LT and ET produce. Further research and a better understanding of these mechanisms may lead to improved management of B. anthracis in patients.
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Affiliation(s)
- Dante A Suffredini
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | - Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | - Wanying Xu
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | - Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
| | - Peter Q Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C145, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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9
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Shaler CR, Choi J, Rudak PT, Memarnejadian A, Szabo PA, Tun-Abraham ME, Rossjohn J, Corbett AJ, McCluskey J, McCormick JK, Lantz O, Hernandez-Alejandro R, Haeryfar SM. MAIT cells launch a rapid, robust and distinct hyperinflammatory response to bacterial superantigens and quickly acquire an anergic phenotype that impedes their cognate antimicrobial function: Defining a novel mechanism of superantigen-induced immunopathology and immunosuppression. PLoS Biol 2017. [PMID: 28632753 PMCID: PMC5478099 DOI: 10.1371/journal.pbio.2001930] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [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] [Indexed: 12/11/2022] Open
Abstract
Superantigens (SAgs) are potent exotoxins secreted by Staphylococcus aureus and Streptococcus pyogenes. They target a large fraction of T cell pools to set in motion a "cytokine storm" with severe and sometimes life-threatening consequences typically encountered in toxic shock syndrome (TSS). Given the rapidity with which TSS develops, designing timely and truly targeted therapies for this syndrome requires identification of key mediators of the cytokine storm's initial wave. Equally important, early host responses to SAgs can be accompanied or followed by a state of immunosuppression, which in turn jeopardizes the host's ability to combat and clear infections. Unlike in mouse models, the mechanisms underlying SAg-associated immunosuppression in humans are ill-defined. In this work, we have identified a population of innate-like T cells, called mucosa-associated invariant T (MAIT) cells, as the most powerful source of pro-inflammatory cytokines after exposure to SAgs. We have utilized primary human peripheral blood and hepatic mononuclear cells, mouse MAIT hybridoma lines, HLA-DR4-transgenic mice, MAIThighHLA-DR4+ bone marrow chimeras, and humanized NOD-scid IL-2Rγnull mice to demonstrate for the first time that: i) mouse and human MAIT cells are hyperresponsive to SAgs, typified by staphylococcal enterotoxin B (SEB); ii) the human MAIT cell response to SEB is rapid and far greater in magnitude than that launched by unfractionated conventional T, invariant natural killer T (iNKT) or γδ T cells, and is characterized by production of interferon (IFN)-γ, tumor necrosis factor (TNF)-α and interleukin (IL)-2, but not IL-17A; iii) high-affinity MHC class II interaction with SAgs, but not MHC-related protein 1 (MR1) participation, is required for MAIT cell activation; iv) MAIT cell responses to SEB can occur in a T cell receptor (TCR) Vβ-specific manner but are largely contributed by IL-12 and IL-18; v) as MAIT cells are primed by SAgs, they also begin to develop a molecular signature consistent with exhaustion and failure to participate in antimicrobial defense. Accordingly, they upregulate lymphocyte-activation gene 3 (LAG-3), T cell immunoglobulin and mucin-3 (TIM-3), and/or programmed cell death-1 (PD-1), and acquire an anergic phenotype that interferes with their cognate function against Klebsiella pneumoniae and Escherichia coli; vi) MAIT cell hyperactivation and anergy co-utilize a signaling pathway that is governed by p38 and MEK1/2. Collectively, our findings demonstrate a pathogenic, rather than protective, role for MAIT cells during infection. Furthermore, we propose a novel mechanism of SAg-associated immunosuppression in humans. MAIT cells may therefore provide an attractive therapeutic target for the management of both early and late phases of severe SAg-mediated illnesses.
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MESH Headings
- Animals
- Antigens, Bacterial/metabolism
- Antigens, Bacterial/toxicity
- Bone Marrow Cells/cytology
- Bone Marrow Cells/drug effects
- Bone Marrow Cells/immunology
- Bone Marrow Cells/metabolism
- Cell Line
- Cells, Cultured
- Clonal Anergy/drug effects
- Crosses, Genetic
- Enterotoxins/metabolism
- Enterotoxins/toxicity
- Female
- Humans
- Hybridomas
- Immunity, Innate
- Leukocytes, Mononuclear/cytology
- Leukocytes, Mononuclear/drug effects
- Leukocytes, Mononuclear/immunology
- Leukocytes, Mononuclear/metabolism
- Lymphocyte Activation/drug effects
- Mice
- Mice, Inbred NOD
- Mice, Knockout
- Mice, SCID
- Mice, Transgenic
- Models, Immunological
- Mucosal-Associated Invariant T Cells/cytology
- Mucosal-Associated Invariant T Cells/drug effects
- Mucosal-Associated Invariant T Cells/immunology
- Mucosal-Associated Invariant T Cells/metabolism
- Specific Pathogen-Free Organisms
- Staphylococcus aureus/immunology
- Staphylococcus aureus/metabolism
- Streptococcus pyogenes/immunology
- Streptococcus pyogenes/metabolism
- Superantigens/metabolism
- Superantigens/toxicity
- Transplantation Chimera/blood
- Transplantation Chimera/immunology
- Transplantation Chimera/metabolism
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Affiliation(s)
- Christopher R. Shaler
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Joshua Choi
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Patrick T. Rudak
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Arash Memarnejadian
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Peter A. Szabo
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
| | - Mauro E. Tun-Abraham
- Division of General Surgery, Department of Surgery, Western University, London, Ontario, Canada
| | - Jamie Rossjohn
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
- Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia
- Institute of Infection and Immunity, Cardiff University School of Medicine, Cardiff, United Kingdom
| | - Alexandra J. Corbett
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia
| | - James McCluskey
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Parkville, Victoria, Australia
| | - John K. McCormick
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
- Centre for Human Immunology, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
| | - Olivier Lantz
- Laboratoire d'Immunologie and INSERM U932, Institut Curie, Paris, France
| | - Roberto Hernandez-Alejandro
- Division of General Surgery, Department of Surgery, Western University, London, Ontario, Canada
- Division of Transplantation, Department of Surgery, University of Rochester Medical Center, Rochester, New York, United States of America
| | - S.M. Mansour Haeryfar
- Department of Microbiology and Immunology, Western University, London, Ontario, Canada
- Centre for Human Immunology, Western University, London, Ontario, Canada
- Lawson Health Research Institute, London, Ontario, Canada
- Division of Clinical Immunology and Allergy, Department of Medicine, Western University, London, Ontario, Canada
- * E-mail:
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10
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Abstract
Anthrax is a severe, although rather rare, infectious disease that is caused by the Gram-positive, spore-forming bacterium Bacillus anthracis. The infectious form is the spore and the major virulence factors of the bacterium are its poly-γ-D-glutamic acid capsule and the tripartite anthrax toxin. The discovery of the anthrax toxin receptors in the early 2000s has allowed in-depth studies on the mechanisms of anthrax toxin cellular entry and translocation from the endocytic compartment to the cytoplasm. The toxin generally hijacks the endocytic pathway of CMG2 and TEM8, the two anthrax toxin receptors, in order to reach the endosomes. From there, the pore-forming subunit of the toxin inserts into endosomal membranes and enables translocation of the two catalytic subunits. Insertion of the pore-forming unit preferentially occurs in intraluminal vesicles rather than the limiting membrane of the endosome, leading to the translocation of the enzymatic subunits in the lumen of these vesicles. This has important consequences that will be discussed. Ultimately, the toxins reach the cytosol where they act on their respective targets. Target modification has severe consequences on cell behavior, in particular on cells of the immune system, allowing the spread of the bacterium, in severe cases leading to host death. Here we will review the literature on anthrax disease with a focus on the structure of the toxin, how it enters cells and its immunological effects.
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Affiliation(s)
- Sarah Friebe
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
| | - F Gisou van der Goot
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
| | - Jérôme Bürgi
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
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11
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Zhao T, Zhao X, Liu J, Meng Y, Feng Y, Fang T, Zhang J, Yang X, Li J, Xu J, Chen W. Diminished but Not Abolished Effect of Two His351 Mutants of Anthrax Edema Factor in a Murine Model. Toxins (Basel) 2016; 8:35. [PMID: 26848687 PMCID: PMC4773788 DOI: 10.3390/toxins8020035] [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] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 01/08/2016] [Accepted: 01/15/2016] [Indexed: 01/14/2023] Open
Abstract
Edema toxin (ET), which is composed of a potent adenylate cyclase (AC), edema factor (EF), and protective antigen (PA), is one of the major toxicity factors of Bacillus anthracis. In this study, we introduced mutations in full-length EF to generate alanine EF(H351A) and arginine EF(H351R) variants. In vitro activity analysis displayed that the adenylyl cyclase activity of both the mutants was significantly diminished compared with the wild-type EF. When the native and mutant toxins were administered subcutaneously in a mouse footpad edema model, severe acute swelling was evoked by wild-type ET, while the symptoms induced by mutant toxins were very minor. Systemic administration of these EF variants caused non-lethal hepatotoxicity. In addition, EF(H351R) exhibited slightly higher activity in causing more severe edema than EF(H351A). Our findings demonstrate that the toxicity of ET is not abolished by substitution of EF residue His351 by alanine or arginine. These results also indicate the potential of the mouse footpad edema model as a sensitive method for evaluating both ET toxicity and the efficacy of candidate therapeutic agents.
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Affiliation(s)
- Taoran Zhao
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Xinghui Zhao
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Ju Liu
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Yingying Meng
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Yingying Feng
- Department of Colorectal Surgery, the Second Artillery General Hospital, Beijing 100088, China.
| | - Ting Fang
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Jinlong Zhang
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Xiuxu Yang
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Jianmin Li
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Junjie Xu
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Wei Chen
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
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12
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Li L, Guo Q, Liu J, Zhang J, Yin Y, Dong D, Fu L, Xu J, Chen W. Recombinant HSA-CMG2 Is a Promising Anthrax Toxin Inhibitor. Toxins (Basel) 2016; 8:toxins8010028. [PMID: 26805881 PMCID: PMC4728550 DOI: 10.3390/toxins8010028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [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: 10/30/2015] [Revised: 12/25/2015] [Accepted: 01/13/2016] [Indexed: 12/20/2022] Open
Abstract
Anthrax toxin is the major virulence factor produced by Bacillus anthracis. Protective antigen (PA) is the key component of the toxin and has been confirmed as the main target for the development of toxin inhibitors. The inhibition of the binding of PA to its receptor, capillary morphogenesis protein-2 (CMG2), can effectively block anthrax intoxication. The recombinant, soluble von Willebrand factor type A (vWA) domain of CMG2 (sCMG2) has demonstrated potency against anthrax toxin. However, the short half-life of sCMG2 in vivo is a disadvantage for its development as a new anthrax drug. In the present study, we report that HSA-CMG2, a protein combining human serum albumin (HSA) and sCMG2, produced in the Pichia pastoris expression system prolonged the half-life of sCMG2 while maintaining PA binding ability. The IC50 of HSA-CMG2 is similar to those of sCMG2 and CMG2-Fc in in vitro toxin neutralization assays, and HSA-CMG2 completely protects rats from lethal doses of anthrax toxin challenge; these same challenge doses exceed sCMG2 at a sub-equivalent dose ratio and overwhelm CMG2-Fc. Our results suggest that HSA-CMG2 is a promising inhibitor of anthrax toxin and may contribute to the development of novel anthrax drugs.
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Affiliation(s)
- Liangliang Li
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
- Center for Disease Control and Prevention of Navy, Beijing 101113, China.
| | - Qiang Guo
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Ju Liu
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Jun Zhang
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Ying Yin
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Dayong Dong
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Ling Fu
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Junjie Xu
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Wei Chen
- Laboratory of Vaccine and Antibody Engineering, Beijing Institute of Biotechnology, Beijing 100071, China.
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13
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Zhang Z, Zhang Y, Shi M, Ye B, Shen W, Li P, Xing L, Zhang X, Hou L, Xu J, Zhao Z, Chen W. Anthrax Susceptibility: Human Genetic Polymorphisms Modulating ANTXR2 Expression. Toxins (Basel) 2015; 8:toxins8010001. [PMID: 26703731 PMCID: PMC4728523 DOI: 10.3390/toxins8010001] [Citation(s) in RCA: 9] [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: 09/11/2015] [Revised: 11/29/2015] [Accepted: 12/09/2015] [Indexed: 01/03/2023] Open
Abstract
Anthrax toxin causes anthrax pathogenesis and expression levels of ANTXR2 (anthrax toxin receptor 2) are strongly correlated with anthrax toxin susceptibility. Previous studies found that ANTXR2 transcript abundance varies considerably in individuals of different ethnic/geographical groups, but no eQTLs (expression quantitative trait loci) have been identified. By using 3C (chromatin conformation capture), CRISPR-mediated genomic deletion and dual-luciferase reporter assay, gene loci containing cis-regulatory elements of ANTXR2 were localized. Two SNPs (single nucleotide polymorphism) at the conserved CREB-binding motif, rs13140055 and rs80314910 in the promoter region of the gene, modulating ANTXR2 promoter activity were identified. Combining these two regulatory SNPs with a previously reported SNP, rs12647691, for the first time, a statistically significant correlation between human genetic variations and anthrax toxin sensitivity was observed. These findings further our understanding of human variability in ANTXR2 expression and anthrax toxin susceptibility.
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Affiliation(s)
- Zhang Zhang
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Yan Zhang
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Minglei Shi
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Bingyu Ye
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Wenlong Shen
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Ping Li
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Lingyue Xing
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Xiaopeng Zhang
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Lihua Hou
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Junjie Xu
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Zhihu Zhao
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
| | - Wei Chen
- Beijing Institute of Biotechnology, No. 20, Dongdajie str., Fengtai District, Beijing 100071, China.
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14
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Reddy PN, Paul S, Sripathy MH, Batra HV. Evaluation of recombinant SEA-TSST fusion toxoid for protection against superantigen induced toxicity in mouse model. Toxicon 2015; 103:106-13. [PMID: 26091873 DOI: 10.1016/j.toxicon.2015.06.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [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: 01/11/2015] [Revised: 06/04/2015] [Accepted: 06/08/2015] [Indexed: 11/18/2022]
Abstract
Treatment of Staphylococcus aureus infections has become complicated owing to growing antibiotic resistance mechanisms and due to the multitude of virulence factors secreted by this organism. Failures with traditional monovalent vaccines or toxoids have brought a shift towards the use of multivalent formulas and neutralizing antibodies to combat and prevent range of staphylococcal infections. In this study, we evaluated the efficacy of a fusion protein (r-ET) comprising truncated regions of staphylococcal enterotoxin A (SEA) and toxic shock syndrome toxin (TSST-1) in generating neutralizing antibodies against superantigen induced toxicity in murine model. Serum antibodies showed specific reactivity to both SEA and TSST-1 native toxins. Hyperimmune serum from immunized animals protected cultured splenocytes from non-specific superantigen induced proliferation completely. Passive antibody administration prevented tissue damage from acute inflammation associated with superantigen challenge from S. aureus cell free culture supernatants. Approximately 80% and 50% of actively and passively immunized mice respectively were protected from lethal dose against S. aureus toxin challenge. This study revealed that r-ET protein is non-toxic and a strong immunogen which generated neutralizing antibodies and memory immune response against superantigen induced toxic effects in mice model.
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Affiliation(s)
| | - Soumya Paul
- Department of Microbiology, Defence Food Research Laboratory, Mysore 570011, India
| | - Murali H Sripathy
- Department of Microbiology, Defence Food Research Laboratory, Mysore 570011, India
| | - Harsh Vardhan Batra
- Department of Microbiology, Defence Food Research Laboratory, Mysore 570011, India.
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15
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Abstract
Anthrax toxin is formed from three components: protective antigen (PA), lethal (LF) and edema (EF) factors. PA83 is cleaved by cell surface protease furin to produce a 63-kDa fragment (PA63). PA63 and LF/EF molecules are assembled to anthrax toxin complexes: oligomer PA63 x 7 + LF/EF x 3. Assembly is occurred during of binding with cellular receptor or near surface of target-cell. This toxin complex forms pore and induces receptor-mediated endocytosis. Formed endosome consists extracellular liquid with LF/EF and membrane-associated ferments (H+ and K+/Na+-ATPases) and proteins (receptors and others). H+ concentration is increased into endosome as result of K/Na-ATPase-dependent- activity of H+-ATPase. Difference of potentials (between endosome and intracellular liquid) is increased and LF/EF molecules are moved to pore and bound with PA63-oligomer to PA63 x 7 + LF/EF x 7 and full block pore (ion-selective channel). Endosome is increased in volume and induces increasing of PA63-oligomer pore to.size of effector complex: LF/EF x 7 + PAl7 x 7 = 750 kDa. Effector complex is translocated from endosome to cytosol by means high difference of potentials (H+) and dissociates from PA47 x 7 complex after cleavage of FFD315-sait by intracellular chymotrypsin-like proteases in all 7 molecules PA63. PA47 x 7 complex (strongly fixed in membrane with debris of hydrophobic loops) return into endosome and pore is destroyed. Endosome pH is decreased rapidly and PA47 x 7 complex is destroyed by endosomal/lysosomal proteases. Receptor-mediated endocytosis is ended by endosome recycling in cell-membrane.
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16
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Guo CY, Huang YH, Wei SN, Ouyang ZL, Yan Y, Huang XH, Qin QW. Establishment of a new cell line from the heart of giant grouper, Epinephelus lanceolatus (Bloch), and its application in toxicology and virus susceptibility. J Fish Dis 2015; 38:175-186. [PMID: 24372271 DOI: 10.1111/jfd.12221] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/20/2013] [Accepted: 11/21/2013] [Indexed: 06/03/2023]
Abstract
A new marine fish cell line, derived from the heart of giant grouper, Epinephelus lanceolatus (Bloch), was established and characterized. The cell line was designated as ELGH and subcultured with more than 60 passages. The ELGH cells were mainly composed of fibroblast-like cells and multiplied well in Leibovitz's L-15 medium supplemented with 10% foetal bovine serum (FBS) at 28 °C. Chromosome analysis indicated that the modal chromosome number was 48. The fluorescent signals were detected in ELGH when transfected with green fluorescent protein reporter plasmids. The 50% cytotoxic concentration (CC50 ) of the extracellular products (ECPs) from Streptococcus iniae and Vibrio alginolyticus E333 on ELGH cells was 60.02 and 12.49 μg mL(-1), respectively. Moreover, the ELGH cells showed susceptibility to Singapore grouper iridovirus (SGIV), but not to soft-shelled turtle iridovirus (STIV), red-spotted grouper nervous necrosis virus (RGNNV) and spring viremia of carp virus (SVCV), which was demonstrated by the presence of a severe cytopathic effect (CPE) and increased viral titres. In addition, electron microscopy observation showed that abundant virus particles were present in the infected cells. Taken together, our data above provided the potential utility of ELGH cells for transgenic and genetic manipulation, as well as cytotoxicity testing and virus pathogenesis.
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Affiliation(s)
- C Y Guo
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China
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17
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Chang HH, Chiang YW, Lin TK, Lin GL, Lin YY, Kau JH, Huang HH, Hsu HL, Wang JH, Sun DS. Erythrocytic mobilization enhanced by the granulocyte colony-stimulating factor is associated with reduced anthrax-lethal-toxin-induced mortality in mice. PLoS One 2014; 9:e111149. [PMID: 25384016 PMCID: PMC4226491 DOI: 10.1371/journal.pone.0111149] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [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: 02/18/2014] [Accepted: 09/26/2014] [Indexed: 12/27/2022] Open
Abstract
Anthrax lethal toxin (LT), one of the primary virulence factors of Bacillus anthracis, causes anthrax-like symptoms and death in animals. Experiments have indicated that levels of erythrocytopenia and hypoxic stress are associated with disease severity after administering LT. In this study, the granulocyte colony-stimulating factor (G-CSF) was used as a therapeutic agent to ameliorate anthrax-LT- and spore-induced mortality in C57BL/6J mice. We demonstrated that G-CSF promoted the mobilization of mature erythrocytes to peripheral blood, resulting in a significantly faster recovery from erythrocytopenia. In addition, combined treatment using G-CSF and erythropoietin tended to ameliorate B. anthracis-spore-elicited mortality in mice. Although specific treatments against LT-mediated pathogenesis remain elusive, these results may be useful in developing feasible strategies to treat anthrax.
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Affiliation(s)
- Hsin-Hou Chang
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
- Institute of Medical Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Ya-Wen Chiang
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Ting-Kai Lin
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Guan-Ling Lin
- Institute of Medical Sciences, Tzu-Chi University, Hualien, Taiwan
| | - You-Yen Lin
- Institute of Medical Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Jyh-Hwa Kau
- Department of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan
| | - Hsin-Hsien Huang
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Hui-Ling Hsu
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Jen-Hung Wang
- Department of Medical Research, Tzu Chi General Hospital, Hualien, Taiwan
| | - Der-Shan Sun
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
- Institute of Medical Sciences, Tzu-Chi University, Hualien, Taiwan
- * E-mail:
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18
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Qian L, Cai C, Yuan P, Jeong SY, Yang X, Dealmeida V, Ernst J, Costa M, Cohen SN, Wei W. Bidirectional effect of Wnt signaling antagonist DKK1 on the modulation of anthrax toxin uptake. Sci China Life Sci 2014; 57:469-81. [PMID: 24671437 DOI: 10.1007/s11427-014-4646-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Accepted: 03/07/2014] [Indexed: 01/07/2023]
Abstract
LRP6, a co-receptor for the morphogen Wnt, aids endocytosis of anthrax complexes. Here we report that Dickkopf1 (DKK1) protein, a secreted LRP6 ligand and antagonist, is also a modulator of anthrax toxin sensitivity. shRNA-mediated gene silencing or TALEN-mediated gene knockout of DKK1 reduced sensitivity of cells to PA-dependent hybrid toxins. However, unlike the solely inhibitory effect on Wnt signaling, the effects of DKK1 overexpression on anthrax toxicity were bidirectional, depending on its endogenous expression and cell context. Fluorescence microscopy and biochemical analyses showed that DKK1 facilitates internalization of anthrax toxins and their receptors, an event mediated by DKK1-LRP6-Kremen2 complex. Monoclonal antibodies against DKK1 provided dose-dependent protection to macrophages from killing by anthrax lethal toxin (LT). Our discovery that DKK1 forms ternary structure with LRP6 and Kremen2 in promoting PA-mediated toxin internalization provides a paradigm for bacterial exploitation of mechanisms that host cells use to internalize signaling proteins.
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Affiliation(s)
- LiLi Qian
- College of Life Sciences and State Key Laboratory of Protein and Plant Gene Research, Peking University, Beijing, 100871, China
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19
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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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20
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Premkumar L, Heras B, Duprez W, Walden P, Halili M, Kurth F, Fairlie DP, Martin JL. Rv2969c, essential for optimal growth in Mycobacterium tuberculosis, is a DsbA-like enzyme that interacts with VKOR-derived peptides and has atypical features of DsbA-like disulfide oxidases. Acta Crystallogr D Biol Crystallogr 2013; 69:1981-94. [PMID: 24100317 PMCID: PMC3792642 DOI: 10.1107/s0907444913017800] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/28/2013] [Indexed: 12/16/2022]
Abstract
The bacterial disulfide machinery is an attractive molecular target for developing new antibacterials because it is required for the production of multiple virulence factors. The archetypal disulfide oxidase proteins in Escherichia coli (Ec) are DsbA and DsbB, which together form a functional unit: DsbA introduces disulfides into folding proteins and DsbB reoxidizes DsbA to maintain it in the active form. In Mycobacterium tuberculosis (Mtb), no DsbB homologue is encoded but a functionally similar but structurally divergent protein, MtbVKOR, has been identified. Here, the Mtb protein Rv2969c is investigated and it is shown that it is the DsbA-like partner protein of MtbVKOR. It is found that it has the characteristic redox features of a DsbA-like protein: a highly acidic catalytic cysteine, a highly oxidizing potential and a destabilizing active-site disulfide bond. Rv2969c also has peptide-oxidizing activity and recognizes peptide segments derived from the periplasmic loops of MtbVKOR. Unlike the archetypal EcDsbA enzyme, Rv2969c has little or no activity in disulfide-reducing and disulfide-isomerase assays. The crystal structure of Rv2969c reveals a canonical DsbA fold comprising a thioredoxin domain with an embedded helical domain. However, Rv2969c diverges considerably from other DsbAs, including having an additional C-terminal helix (H8) that may restrain the mobility of the catalytic helix H1. The enzyme is also characterized by a very shallow hydrophobic binding surface and a negative electrostatic surface potential surrounding the catalytic cysteine. The structure of Rv2969c was also used to model the structure of a paralogous DsbA-like domain of the Ser/Thr protein kinase PknE. Together, these results show that Rv2969c is a DsbA-like protein with unique properties and a limited substrate-binding specificity.
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Affiliation(s)
- Lakshmanane Premkumar
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, St Lucia, QLD 4067, Australia
| | - Begoña Heras
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, St Lucia, QLD 4067, Australia
| | - Wilko Duprez
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, St Lucia, QLD 4067, Australia
| | - Patricia Walden
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, St Lucia, QLD 4067, Australia
| | - Maria Halili
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, St Lucia, QLD 4067, Australia
| | - Fabian Kurth
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, St Lucia, QLD 4067, Australia
| | - David P. Fairlie
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, St Lucia, QLD 4067, Australia
| | - Jennifer L. Martin
- Institute for Molecular Bioscience, Division of Chemistry and Structural Biology, University of Queensland, St Lucia, QLD 4067, Australia
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21
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Chang HH, Wang TP, Chen PK, Lin YY, Liao CH, Lin TK, Chiang YW, Lin WB, Chiang CY, Kau JH, Huang HH, Hsu HL, Liao CY, Sun DS. Erythropoiesis suppression is associated with anthrax lethal toxin-mediated pathogenic progression. PLoS One 2013; 8:e71718. [PMID: 23977125 PMCID: PMC3747219 DOI: 10.1371/journal.pone.0071718] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [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: 03/14/2013] [Accepted: 07/01/2013] [Indexed: 01/01/2023] Open
Abstract
Anthrax is a disease caused by the bacterium Bacillus anthracis, which results in high mortality in animals and humans. Although some of the mechanisms are already known such as asphyxia, extensive knowledge of molecular pathogenesis of this disease is deficient and remains to be further investigated. Lethal toxin (LT) is a major virulence factor of B. anthracis and a specific inhibitor/protease of mitogen-activated protein kinase kinases (MAPKKs). Anthrax LT causes lethality and induces certain anthrax-like symptoms, such as anemia and hypoxia, in experimental mice. Mitogen-activated protein kinases (MAPKs) are the downstream pathways of MAPKKs, and are important for erythropoiesis. This prompted us to hypothesize that anemia and hypoxia may in part be exacerbated by erythropoietic dysfunction. As revealed by colony-forming cell assays in this study, LT challenges significantly reduced mouse erythroid progenitor cells. In addition, in a proteolytic activity-dependent manner, LT suppressed cell survival and differentiation of cord blood CD34+-derived erythroblasts in vitro. Suppression of cell numbers and the percentage of erythroblasts in the bone marrow were detected in LT-challenged C57BL/6J mice. In contrast, erythropoiesis was provoked through treatments of erythropoietin, significantly ameliorating the anemia and reducing the mortality of LT-treated mice. These data suggested that suppressed erythropoiesis is part of the pathophysiology of LT-mediated intoxication. Because specific treatments to overcome LT-mediated pathogenesis are still lacking, these efforts may help the development of effective treatments against anthrax.
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Affiliation(s)
- Hsin-Hou Chang
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
- Institute of Medical Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Tsung-Pao Wang
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Po-Kong Chen
- Institute of Medical Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Yo-Yin Lin
- Institute of Medical Sciences, Tzu-Chi University, Hualien, Taiwan
| | - Chih-Hsien Liao
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Ting-Kai Lin
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Ya-Wen Chiang
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Wen-Bin Lin
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Chih-Yu Chiang
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Jyh-Hwa Kau
- Department of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan
| | - Hsin-Hsien Huang
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Hui-Ling Hsu
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Chi-Yuan Liao
- Department of Obstetrics and Gynecology, Mennonite Christian HospitalHualien, Taiwan
| | - Der-Shan Sun
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
- Institute of Medical Sciences, Tzu-Chi University, Hualien, Taiwan
- * E-mail:
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22
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Dedieu L, Serveau-Avesque C, Canaan S. Identification of residues involved in substrate specificity and cytotoxicity of two closely related cutinases from Mycobacterium tuberculosis. PLoS One 2013; 8:e66913. [PMID: 23843969 PMCID: PMC3699616 DOI: 10.1371/journal.pone.0066913] [Citation(s) in RCA: 14] [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: 02/27/2013] [Accepted: 05/11/2013] [Indexed: 11/20/2022] Open
Abstract
The enzymes belonging to the cutinase family are serine enzymes active on a large panel of substrates such as cutin, triacylglycerols, and phospholipids. In the M. tuberculosis H37Rv genome, seven genes coding for cutinase-like proteins have been identified with strong immunogenic properties suggesting a potential role as vaccine candidates. Two of these enzymes which are secreted and highly homologous, possess distinct substrates specificities. Cfp21 is a lipase and Cut4 is a phospholipase A2, which has cytotoxic effects on macrophages. Structural overlay of their three-dimensional models allowed us to identify three areas involved in the substrate binding process and to shed light on this substrate specificity. By site-directed mutagenesis, residues present in these Cfp21 areas were replaced by residues occurring in Cut4 at the same location. Three mutants acquired phospholipase A1 and A2 activities and the lipase activities of two mutants were 3 and 15 fold greater than the Cfp21 wild type enzyme. In addition, contrary to mutants with enhanced lipase activity, mutants that acquired phospholipase B activities induced macrophage lysis as efficiently as Cut4 which emphasizes the relationship between apparent phospholipase A2 activity and cytotoxicity. Modification of areas involved in substrate specificity, generate recombinant enzymes with higher activity, which may be more immunogenic than the wild type enzymes and could therefore constitute promising candidates for antituberculous vaccine production.
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Affiliation(s)
- Luc Dedieu
- CNRS - Aix-Marseille Université - Enzymologie Interfaciale et Physiologie de la Lipolyse - UMR 7282, Marseille, France
| | - Carole Serveau-Avesque
- CNRS - Aix-Marseille Université - Enzymologie Interfaciale et Physiologie de la Lipolyse - UMR 7282, Marseille, France
| | - Stéphane Canaan
- CNRS - Aix-Marseille Université - Enzymologie Interfaciale et Physiologie de la Lipolyse - UMR 7282, Marseille, France
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23
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Chen PK, Chang HH, Lin GL, Wang TP, Lai YL, Lin TK, Hsieh MC, Kau JH, Huang HH, Hsu HL, Liao CY, Sun DS. Suppressive effects of anthrax lethal toxin on megakaryopoiesis. PLoS One 2013; 8:e59512. [PMID: 23555687 PMCID: PMC3605335 DOI: 10.1371/journal.pone.0059512] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [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: 09/03/2012] [Accepted: 02/15/2013] [Indexed: 01/14/2023] Open
Abstract
Anthrax lethal toxin (LT) is a major virulence factor of Bacillus anthracis. LT challenge suppresses platelet counts and platelet function in mice, however, the mechanism responsible for thrombocytopenia remains unclear. LT inhibits cellular mitogen-activated protein kinases (MAPKs), which are vital pathways responsible for cell survival, differentiation, and maturation. One of the MAPKs, the MEK1/2-extracellular signal-regulated kinase pathway, is particularly important in megakaryopoiesis. This study evaluates the hypothesis that LT may suppress the progenitor cells of platelets, thereby inducing thrombocytopenic responses. Using cord blood-derived CD34(+) cells and mouse bone marrow mononuclear cells to perform in vitro differentiation, this work shows that LT suppresses megakaryopoiesis by reducing the survival of megakaryocytes. Thrombopoietin treatments can reduce thrombocytopenia, megakaryocytic suppression, and the quick onset of lethality in LT-challenged mice. These results suggest that megakaryocytic suppression is one of the mechanisms by which LT induces thrombocytopenia. These findings may provide new insights for developing feasible approaches against anthrax.
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Affiliation(s)
- Po-Kong Chen
- Institute of Medical Science, Tzu-Chi University, Hualien, Taiwan
| | - Hsin-Hou Chang
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
- Institute of Medical Science, Tzu-Chi University, Hualien, Taiwan
| | - Guan-Ling Lin
- Institute of Medical Science, Tzu-Chi University, Hualien, Taiwan
| | - Tsung-Pao Wang
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Yi-Ling Lai
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Ting-Kai Lin
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Ming-Chun Hsieh
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
| | - Jyh-Hwa Kau
- Department of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan
| | - Hsin-Hsien Huang
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Hui-Ling Hsu
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Chi-Yuan Liao
- Department of Obstetrics and Gynecology, Mennonite Christian Hospital, Hualien, Taiwan
| | - Der-Shan Sun
- Department of Molecular Biology and Human Genetics, Tzu-Chi University, Hualien, Taiwan
- Institute of Medical Science, Tzu-Chi University, Hualien, Taiwan
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24
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Kenney MJ, Mosher LJ, Fels RJ. Bacillus anthracis lethal toxin induces complex changes in sympathetic nerve discharge regulation. Auton Neurosci 2012; 170:66-9. [PMID: 22818628 DOI: 10.1016/j.autneu.2012.06.007] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 06/25/2012] [Accepted: 06/28/2012] [Indexed: 11/16/2022]
Abstract
Bacillus anthracis lethal toxin (LeTx) alters blood pressure and visceral sympathetic nerve discharge (SND) regulation (Garcia et al., 2012). The present results indicate that LeTx infusions produce similar response profiles in peripheral (lumbar) and visceral (renal) SND; an initial widespread activation of sympathetic nerve outflow, followed by a generalized reduction in lumbar and renal SND from peak levels, although the sympathoinhibition tended to be attenuated in lumbar SND. Combined hypoxia+hypercapnia during the hypotensive phase of LeTx infusions increased lumbar and renal SND, indicating that sympathetic neural circuits can be activated during the circulatory shock phase of B. anthracis septicemia.
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Affiliation(s)
- M J Kenney
- Department of Anatomy and Physiology, Kansas State University, Manhattan, USA.
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Göttle M, Dove S, Seifert R. Bacillus anthracis edema factor substrate specificity: evidence for new modes of action. Toxins (Basel) 2012; 4:505-35. [PMID: 22852066 PMCID: PMC3407890 DOI: 10.3390/toxins4070505] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [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: 04/23/2012] [Revised: 06/15/2012] [Accepted: 06/27/2012] [Indexed: 12/20/2022] Open
Abstract
Since the isolation of Bacillus anthracis exotoxins in the 1960s, the detrimental activity of edema factor (EF) was considered as adenylyl cyclase activity only. Yet the catalytic site of EF was recently shown to accomplish cyclization of cytidine 5'-triphosphate, uridine 5'-triphosphate and inosine 5'-triphosphate, in addition to adenosine 5'-triphosphate. This review discusses the broad EF substrate specificity and possible implications of intracellular accumulation of cyclic cytidine 3':5'-monophosphate, cyclic uridine 3':5'-monophosphate and cyclic inosine 3':5'-monophosphate on cellular functions vital for host defense. In particular, cAMP-independent mechanisms of action of EF on host cell signaling via protein kinase A, protein kinase G, phosphodiesterases and CNG channels are discussed.
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Affiliation(s)
- Martin Göttle
- Department of Neurology, Emory University School of Medicine, 6302 Woodruff Memorial Research Building, 101 Woodruff Circle, Atlanta, GA 30322, USA
- Author to whom correspondence should be addressed; ; Tel.: +1-404-727-1678; Fax: +1-404-727-3157
| | - Stefan Dove
- Department of Medicinal/Pharmaceutical Chemistry II, University of Regensburg, D-93040 Regensburg, Germany;
| | - Roland Seifert
- Institute of Pharmacology, Medical School of Hannover, Carl-Neuberg-Str. 1, D-30625 Hannover, Germany;
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26
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Thomas D, Naughton J, Cote C, Welkos S, Manchester M, Young JAT. Delayed toxicity associated with soluble anthrax toxin receptor decoy-Ig fusion protein treatment. PLoS One 2012; 7:e34611. [PMID: 22511955 PMCID: PMC3325282 DOI: 10.1371/journal.pone.0034611] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 03/05/2012] [Indexed: 11/21/2022] Open
Abstract
Soluble receptor decoy inhibitors, including receptor-immunogloubulin (Ig) fusion proteins, have shown promise as candidate anthrax toxin therapeutics. These agents act by binding to the receptor-interaction site on the protective antigen (PA) toxin subunit, thereby blocking toxin binding to cell surface receptors. Here we have made the surprising observation that co-administration of receptor decoy-Ig fusion proteins significantly delayed, but did not protect, rats challenged with anthrax lethal toxin. The delayed toxicity was associated with the in vivo assembly of a long-lived complex comprised of anthrax lethal toxin and the receptor decoy-Ig inhibitor. Intoxication in this system presumably results from the slow dissociation of the toxin complex from the inhibitor following their prolonged circulation. We conclude that while receptor decoy-Ig proteins represent promising candidates for the early treatment of B. anthracis infection, they may not be suitable for therapeutic use at later stages when fatal levels of toxin have already accumulated in the bloodstream.
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Affiliation(s)
- Diane Thomas
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
| | - John Naughton
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, California, United States of America
| | - Christopher Cote
- Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Susan Welkos
- Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, United States of America
| | - Marianne Manchester
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, California, United States of America
- * E-mail: (MM); (JATY)
| | - John A. T. Young
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, California, United States of America
- * E-mail: (MM); (JATY)
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Abstract
PURPOSE OF REVIEW Sarcoidosis, the multiorgan granulomatous disease of unknown cause, remains mysterious. Several important investigations in the past 2 years add to the accumulating evidence for both occupational and environmental causes of granulomatous inflammation. RECENT FINDINGS This review considers the most recent studies that contribute to the hypothesis that sarcoidosis occurs when individuals are exposed to foreign antigens and to inorganic particulates that promote inflammation. Major recent findings, such as those emerging from the study of World Trade Center responders, the study of nanoparticles, and cases of work-associated sarcoidosis, support the probability that occupational, as well as environmental, exposures to inflammatory stimuli trigger sarcoidosis-like illness. Major recent studies of microbially rich indoor environments, including moldy indoor workplaces and mycobacterially contaminated settings, contribute to the evidence that a variety of microbial antigens serve as targets for the hypersensitivity immune response in an inflammatory milieu. SUMMARY There is increasing evidence that sarcoidosis can occur in workplace settings in which there is exposure to both foreign antigens and inorganic triggers of inflammation that promote an exuberant granulomatous immune response. It is likely that sarcoidosis has more than one cause.
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Affiliation(s)
- Kira L Newman
- Emory University School of Medicine, Atlanta, Georgia, USA
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28
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Abstract
Bacillus anthracis, the agent of anthrax, has gained virulence through its exotoxins produced by vegetative bacilli and is composed of three components forming lethal toxin (LT) and edema toxin (ET). So far, little is known about the effects of these toxins on the eukaryotic cytoskeleton. Here, we provide an overview on the general effects of toxin upon the cytoskeleton architecture. Thus, we shall discuss how anthrax toxins interact with their receptors and may disrupt the interface between extracellular matrix and the cytoskeleton. We then analyze what toxin molecular effects on cytoskeleton have been described, before discussing how the cytoskeleton may help the pathogen to corrupt general cell processes such as phagocytosis or vascular integrity.
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Affiliation(s)
- Yannick Trescos
- Unité Interactions Hôte-Agents pathogènes, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, BP 87, 24 avenue des Maquis du Grésivaudan 38702 La Tronche Cedex, France;
- Ecole du Val-de-Grâce, 1 place Alphonse Lavéran, 75005 Paris, France
| | - Jean-Nicolas Tournier
- Unité Interactions Hôte-Agents pathogènes, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, BP 87, 24 avenue des Maquis du Grésivaudan 38702 La Tronche Cedex, France;
- Ecole du Val-de-Grâce, 1 place Alphonse Lavéran, 75005 Paris, France
- Author to whom correspondence should be addressed; ; Tel.: +33-4-76636850; Fax: +33-4-76636917
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29
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Abstract
Anthrax lethal toxin (LT) is a major virulence factor of Bacillus anthracis. The vast majority of the anthrax toxin-related literature describes the assembly of LT as a cell-dependent process. However, some reports have provided evidence for the existence of a fully assembled LT, either in vitro or in the bloodstream of anthrax-infected animals. To follow up on this work, we present studies on fully-assembled LT. We first demonstrate facile and cell-free assembly and purification of LT. We then show that fully assembled LT binds an anthrax toxin receptor with almost 100-fold higher affinity than the protective antigen (PA) alone. Quantitative cell intoxication assays were used to determine the LD(50) (lethal dose 50) for LT. The cell-binding studies revealed that LT binds mammalian cells using a different mode from PA. Even when PA-specific receptors were blocked, fully assembled LT was able to bind the cell surface. Our studies support the existing evidence that LT fully assembles in the blood stream and can bind and intoxicate mammalian cells with very high affinity and efficacy. More importantly, the data presented here invoke the possibility that LT may bind cells in a receptor-independent fashion, or recognize receptors that do not interact with PA. Hence, blood borne LT may emerge as a novel therapeutic target for combating anthrax.
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Affiliation(s)
- Momchilo Vuyisich
- Los Alamos National Lab, MS M888, P.O. Box 1663, Los Alamos, NM 87545, USA.
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30
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Abstract
Helicobacter pylori CagA and VacA are two critical virulence factors that modulate disease severity in the infected host. The following chapter outlines methods employed to study the effects of these virulence factors on several key signaling pathways in epithelial cells.
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Affiliation(s)
- Deepa Raju
- Cell Biology Program, Research Institute, Hospital for Sick Children, Toronto, ON, Canada
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Chauncey KM, Szarowicz SE, Sidhu GS, During RL, Southwick FS. Anthrax lethal and edema toxins fail to directly impair human platelet function. J Infect Dis 2011; 205:453-7. [PMID: 22158563 DOI: 10.1093/infdis/jir763] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [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: 11/14/2022] Open
Abstract
Hemorrhage is a prominent clinical manifestation of systemic anthrax. Therefore, we have examined the effects of anthrax lethal and edema toxins on human platelets. We find that anthrax lethal toxin fails to cleave its target, mitogen-activated protein kinase 1, and anthrax edema toxin fails to increase intracellular cyclic adenosine monophosphate. Surface expression of toxin receptors tumor endothelial marker 8 and capillary morphogenesis gene 2, as well as coreceptor low density lipoprotein receptor-related protein 6 (LRP6), are markedly reduced, preventing toxin binding to platelets. Our studies suggest that the hemorrhagic clinical manifestations of systemic anthrax are unlikely to be caused by the direct binding and entry of anthrax toxins into human platelets.
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Affiliation(s)
- Kassidy M Chauncey
- Department of Medicine, University of Florida, Gainesville, FL 32610-0277, USA
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32
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Warfel JM, D’Agnillo F. Anthrax lethal toxin-mediated disruption of endothelial VE-cadherin is attenuated by inhibition of the Rho-associated kinase pathway. Toxins (Basel) 2011; 3:1278-93. [PMID: 22069696 PMCID: PMC3210462 DOI: 10.3390/toxins3101278] [Citation(s) in RCA: 20] [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: 07/08/2011] [Revised: 10/01/2011] [Accepted: 10/09/2011] [Indexed: 01/01/2023] Open
Abstract
Systemic anthrax disease is characterized by vascular leakage pathologies. We previously reported that anthrax lethal toxin (LT) induces human endothelial barrier dysfunction in a cell death-independent manner with actin stress fiber formation and disruption of adherens junctions (AJs). In the present study, we further characterize the molecular changes in the AJ complex and investigate whether AJ structure and barrier function can be preserved by modulating key cytoskeletal signaling pathways. Here, we show that LT reduces total VE-cadherin protein and gene expression but the expression of the key linker protein beta-catenin remained unchanged. The changes in VE-cadherin expression correlated temporally with the appearance of actin stress fibers and a two-fold increase in phosphorylation of the stress fiber-associated protein myosin light chain (p-MLC) and cleavage of Rho-associated kinase-1 (ROCK-1). Co-treatment with ROCK inhibitors (H-1152 and Y27632), but not an inhibitor of MLC kinase (ML-7), blocked LT-induced p-MLC enhancement and stress fiber formation. This was accompanied by the restoration of VE-cadherin expression and membrane localization, and attenuation of the LT-induced increase in monolayer permeability to albumin. Together, these findings suggest the ROCK pathway may be a relevant target for countering LT-mediated endothelial barrier dysfunction.
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Affiliation(s)
- Jason M. Warfel
- Laboratory of Biochemistry and Vascular Biology, Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, MD 20892, USA;
- Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Felice D’Agnillo
- Laboratory of Biochemistry and Vascular Biology, Division of Hematology, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland, MD 20892, USA;
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Hicks CW, Cui X, Sweeney DA, Li Y, Barochia A, Eichacker PQ. The potential contributions of lethal and edema toxins to the pathogenesis of anthrax associated shock. Toxins (Basel) 2011; 3:1185-202. [PMID: 22069762 PMCID: PMC3202877 DOI: 10.3390/toxins3091185] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [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: 08/24/2011] [Revised: 09/08/2011] [Accepted: 09/09/2011] [Indexed: 12/22/2022] Open
Abstract
Outbreaks of Bacillus anthracis in the US and Europe over the past 10 years have emphasized the health threat this lethal bacteria poses even for developed parts of the world. In contrast to cutaneous anthrax, inhalational disease in the US during the 2001 outbreaks and the newly identified injectional drug use form of disease in the UK and Germany have been associated with relatively high mortality rates. One notable aspect of these cases has been the difficulty in supporting patients once shock has developed. Anthrax bacilli produce several different components which likely contribute to this shock. Growing evidence indicates that both major anthrax toxins may produce substantial cardiovascular dysfunction. Lethal toxin (LT) can alter peripheral vascular function; it also has direct myocardial depressant effects. Edema toxin (ET) may have even more pronounced peripheral vascular effects than LT, including the ability to interfere with the actions of conventional vasopressors. Additionally, ET also appears capable of interfering with renal sodium and water retention. Importantly, the two toxins exert their actions via quite different mechanisms and therefore have the potential to worsen shock and outcome in an additive fashion. Finally, both toxins have the ability to inhibit host defense and microbial clearance, possibly contributing to the very high bacterial loads noted in patients dying with anthrax. This last point is clinically relevant since emerging data has begun to implicate other bacterial components such as anthrax cell wall in the shock and organ injury observed with infection. Taken together, accumulating evidence regarding the potential contribution of LT and ET to anthrax-associated shock supports efforts to develop adjunctive therapies that target both toxins in patients with progressive shock.
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Affiliation(s)
- Caitlin W. Hicks
- Cleveland Clinic Lerner College of Medicine, Cleveland, OH 44195, USA;
- Howard Hughes Medical Institute-National Institutes of Health Research Scholar, National Institutes of Health, Bethesda, MD 20814, USA
| | - Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA; (X.C.); (Y.L.); (A.B.)
| | - Daniel A. Sweeney
- Medical Intensivist Program, Washington Hospital, Fremont, CA 94538, USA;
| | - Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA; (X.C.); (Y.L.); (A.B.)
| | - Amisha Barochia
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA; (X.C.); (Y.L.); (A.B.)
| | - Peter Q. Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA; (X.C.); (Y.L.); (A.B.)
- Author to whom correspondence should be addressed; ; Tel.: +1-301-496-9320; Fax: +1-301-402-1213
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34
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Dumas EK, Cox PM, Fullenwider CO, Nguyen M, Centola M, Frank MB, Dozmorov I, James JA, Farris AD. Anthrax lethal toxin-induced gene expression changes in mouse lung. Toxins (Basel) 2011; 3:1111-30. [PMID: 22039574 PMCID: PMC3202878 DOI: 10.3390/toxins3091111] [Citation(s) in RCA: 6] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 08/24/2011] [Accepted: 09/06/2011] [Indexed: 11/16/2022] Open
Abstract
A major virulence factor of Bacillus anthracis is the anthrax Lethal Toxin (LeTx), a bipartite toxin composed of Protective Antigen and Lethal Factor. Systemic administration of LeTx to laboratory animals leads to death associated with vascular leakage and pulmonary edema. In this study, we investigated whether systemic exposure of mice to LeTx would induce gene expression changes associated with vascular/capillary leakage in lung tissue. We observed enhanced susceptibility of A/J mice to death by systemic LeTx administration compared to the C57BL/6 strain. LeTx-induced groups of both up- and down-regulated genes were observed in mouse lungs 6 h after systemic administration of wild type toxin compared to lungs of mice exposed to an inactive mutant form of the toxin. Lungs of the less susceptible C57BL/6 strain showed 80% fewer differentially expressed genes compared to lungs of the more sensitive A/J strain. Expression of genes known to regulate vascular permeability was modulated by LeTx in the lungs of the more susceptible A/J strain. Unexpectedly, the largest set of genes with altered expression was immune specific, characterized by the up-regulation of lymphoid genes and the down-regulation of myeloid genes. Transcripts encoding neutrophil chemoattractants, modulators of tumor regulation and angiogenesis were also differentially expressed in both mouse strains. These studies provide new directions for the investigation of vascular leakage and pulmonary edema induced by anthrax LeTx.
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Affiliation(s)
- Eric K. Dumas
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, 1100 N. Lindsay, Oklahoma City, OK 73104, USA; (E.K.D.); (M.N.); (J.A.J.)
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation; 825 NE 13 Street, MS 53, Oklahoma City, OK 73104, USA; (P.M.C.); (C.O.F.); (M.C.); (M.B.K.); (I.D.)
| | - Philip M. Cox
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation; 825 NE 13 Street, MS 53, Oklahoma City, OK 73104, USA; (P.M.C.); (C.O.F.); (M.C.); (M.B.K.); (I.D.)
| | - Charles O’Connor Fullenwider
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation; 825 NE 13 Street, MS 53, Oklahoma City, OK 73104, USA; (P.M.C.); (C.O.F.); (M.C.); (M.B.K.); (I.D.)
| | - Melissa Nguyen
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, 1100 N. Lindsay, Oklahoma City, OK 73104, USA; (E.K.D.); (M.N.); (J.A.J.)
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation; 825 NE 13 Street, MS 53, Oklahoma City, OK 73104, USA; (P.M.C.); (C.O.F.); (M.C.); (M.B.K.); (I.D.)
| | - Michael Centola
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation; 825 NE 13 Street, MS 53, Oklahoma City, OK 73104, USA; (P.M.C.); (C.O.F.); (M.C.); (M.B.K.); (I.D.)
- Microarray Research Facility, Oklahoma Medical Research Foundation, 825 NE 13th Street, MS 53, Oklahoma City, OK 73104, USA
| | - Mark Barton Frank
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation; 825 NE 13 Street, MS 53, Oklahoma City, OK 73104, USA; (P.M.C.); (C.O.F.); (M.C.); (M.B.K.); (I.D.)
- Microarray Research Facility, Oklahoma Medical Research Foundation, 825 NE 13th Street, MS 53, Oklahoma City, OK 73104, USA
| | - Igor Dozmorov
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation; 825 NE 13 Street, MS 53, Oklahoma City, OK 73104, USA; (P.M.C.); (C.O.F.); (M.C.); (M.B.K.); (I.D.)
| | - Judith A. James
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, 1100 N. Lindsay, Oklahoma City, OK 73104, USA; (E.K.D.); (M.N.); (J.A.J.)
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation; 825 NE 13 Street, MS 53, Oklahoma City, OK 73104, USA; (P.M.C.); (C.O.F.); (M.C.); (M.B.K.); (I.D.)
| | - A. Darise Farris
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, 1100 N. Lindsay, Oklahoma City, OK 73104, USA; (E.K.D.); (M.N.); (J.A.J.)
- Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation; 825 NE 13 Street, MS 53, Oklahoma City, OK 73104, USA; (P.M.C.); (C.O.F.); (M.C.); (M.B.K.); (I.D.)
- Author to whom correspondence should be addressed; ; Tel.: +1-405-271-7389; Fax: +1-405-271-706
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Lawrence WS, Marshall JR, Zavala DL, Weaver LE, Baze WB, Moen ST, Whorton EB, Gourley RL, Peterson JW. Hemodynamic effects of anthrax toxins in the rabbit model and the cardiac pathology induced by lethal toxin. Toxins (Basel) 2011; 3:721-36. [PMID: 22069736 PMCID: PMC3202836 DOI: 10.3390/toxins3060721] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [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: 04/30/2011] [Revised: 06/11/2011] [Accepted: 06/21/2011] [Indexed: 01/13/2023] Open
Abstract
Anthrax lethal toxin (LeTx) and edema toxin (EdTx) have been shown to alter hemodynamics in the rodent model, while LeTx primarily is reported to induce extensive tissue pathology. However, the rodent model has limitations when used for comparison to higher organisms such as humans. The rabbit model, on the other hand, has gained recognition as a useful model for studying anthrax infection and its pathophysiological effects. In this study, we assessed the hemodynamic effects of lethal toxin (LeTx) and edema toxin (EdTx) in the rabbit model using physiologically relevant amounts of the toxins. Moreover, we further examine the pathological effects of LeTx on cardiac tissue. We intravenously injected Dutch-belted rabbits with either low-dose and high-dose recombinant LeTx or a single dose of EdTx. The animals’ heart rate and mean arterial pressure were continuously monitored via telemetry until either 48 or 72 h post-challenge. Additional animals challenged with LeTx were used for cardiac troponin I (cTnI) quantitation, cardiac histopathology, and echocardiography. LeTx depressed heart rate at the lower dose and mean arterial pressure (MAP) at the higher dose. EdTx, on the other hand, temporarily intensified heart rate while lowering MAP. Both doses of LeTx caused cardiac pathology with the higher dose having a more profound effect. Lastly, left-ventricular dilation due to LeTx was not apparent at the given time-points. Our study demonstrates the hemodynamic effects of anthrax toxins, as well as the pathological effects of LeTx on the heart in the rabbit model, and it provides further evidence for the toxins’ direct impact on the heart.
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Affiliation(s)
- William S Lawrence
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston/TX 77555, USA.
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Abstract
Bacillus anthracis, similar to other bacterial pathogens, has evolved effective immune evasion strategies to prolong its survival in the host, thus ensuring the unchecked spread of the infection. This function is subserved by lethal (LT) and edema (ET) toxins, two exotoxins produced by vegetative anthrax bacilli following germination of the spores. The structure of these toxins and the mechanism of cell intoxication are topics covered by other reviews in this issue. Here we shall discuss how B. anthracis uses LT and ET to suppress the immune defenses of the host, focusing on T lymphocytes, the key players in adaptive immunity. We shall also summarize recent findings showing that, depending on its concentration, ET has the ability not only to suppress T cell activation but also to promote the polarization of CD4(+) T cells to the Th2 and Th17 subsets, highlighting the potential use of this toxin as an immunomodulator.
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Affiliation(s)
- Silvia Rossi Paccani
- Department of Evolutionary Biology, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy;
- Novartis Vaccines, Via Fiorentina 1, 53100 Siena, Italy
- Author to whom correspondence should be addressed; or ; Tel.: +39-0577-234396; Fax: +39-0577-234476
| | - Cosima T. Baldari
- Department of Evolutionary Biology, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy;
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Abstract
The pathological actions of anthrax toxin require the activities of its edema factor (EF) and lethal factor (LF) enzyme components, which gain intracellular access via its receptor-binding component, protective antigen (PA). LF is a metalloproteinase with specificity for selected mitogen-activated protein kinase kinases (MKKs), but its activity is not directly lethal to many types of primary and transformed cells in vitro. Nevertheless, in vivo treatment of several animal species with the combination of LF and PA (termed lethal toxin or LT) leads to morbidity and mortality, suggesting that LT-dependent toxicity is mediated by cellular interactions between host cells. Decades of research have revealed that a central hallmark of this toxicity is the disruption of key cellular barriers required to maintain homeostasis. This review will focus on the current understanding of the effects of LT on barrier function, highlighting recent progress in establishing the molecular mechanisms underlying these effects.
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Affiliation(s)
- Tao Xie
- Laboratory of Cell Biology, Division of Monoclonal Antibodies, Office of Biotechnology Products, Office of Pharmaceutical Science, Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Bethesda, MD 20892, USA.
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Blankier S, McCrindle BW, Ito S, Yeung RSM. The role of atorvastatin in regulating the immune response leading to vascular damage in a model of Kawasaki disease. Clin Exp Immunol 2011; 164:193-201. [PMID: 21361911 PMCID: PMC3087911 DOI: 10.1111/j.1365-2249.2011.04331.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [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] [Accepted: 01/06/2011] [Indexed: 02/06/2023] Open
Abstract
Superantigens have been implicated in a number of diseases including Kawasaki disease (KD), a multi-system vasculitis resulting in coronary artery aneurysms. We have characterized a murine disease model in which coronary arteritis is induced by a novel superantigen found in Lactobacillus casei cell wall extract (LCWE). Using this animal model of KD, we have identified three pathogenic steps leading to coronary artery aneurysm formation. These steps include T cell activation and proliferation, production of the proinflammatory cytokine tumour necrosis factor (TNF)-α and up-regulation of matrix metalloproteinase 9 (MMP-9), an elastolytic protease. In addition to their cholesterol-lowering effects, 3-hydroxy-3-methylglutaryl (HMG) coenzyme A (CoA) reductase inhibitors (statins) have pleotropic immunomodulatory properties. Thus, we examined the effect of atorvastatin in modulating each of these three critical pathogenic processes leading to aneurysm formation in the disease model. Atorvastatin inhibited lymphocyte proliferation in response to superantigen stimulation in a dose-dependent manner. This inhibition was also observed for production of soluble mediators of inflammation including interleukin (IL)-2 and TNF-α. The inhibitory effect on proliferation was rescued completely by mevalonic acid, confirming that the mechanism responsible for this inhibitory activity on immune activation was inhibition of HMG-CoA reductase. Similarly, TNF-α-induced MMP-9 production was reduced in a dose-dependent manner in response to atorvastatin. Inhibition of extracellular-regulated kinase (ERK) phosphorylation appears to be the mechanism responsible for inhibition of MMP-9 production. In conclusion, atorvastatin is able to inhibit critical steps known to be important in the development of coronary aneurysms, suggesting that statins may have therapeutic benefit in patients with KD.
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Affiliation(s)
- S Blankier
- Cell Biology Program, The Hospital for Sick Children Research Institute, Toronto, Canada
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Hicks CW, Li Y, Okugawa S, Solomon SB, Moayeri M, Leppla SH, Mohanty A, Subramanian GM, Mignone TS, Fitz Y, Cui X, Eichacker PQ. Anthrax edema toxin has cAMP-mediated stimulatory effects and high-dose lethal toxin has depressant effects in an isolated perfused rat heart model. Am J Physiol Heart Circ Physiol 2011; 300:H1108-18. [PMID: 21217068 PMCID: PMC3064307 DOI: 10.1152/ajpheart.01128.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 01/04/2011] [Indexed: 12/23/2022]
Abstract
While anthrax edema toxin produces pronounced tachycardia and lethal toxin depresses left ventricular (LV) ejection fraction in in vivo models, whether these changes reflect direct cardiac effects as opposed to indirect ones related to preload or afterload alterations is unclear. In the present study, the effects of edema toxin and lethal toxin were investigated in a constant pressure isolated perfused rat heart model. Compared with control hearts, edema toxin at doses comparable to or less than a dose that produced an 80% lethality rate (LD(80)) in vivo in rats (200, 100, and 50 ng/ml) produced rapid increases in heart rate (HR), coronary flow (CF), LV developed pressure (LVDP), dP/dt(max), and rate-pressure product (RPP) that were most pronounced and persisted with the lowest dose (P ≤ 0.003). Edema toxin (50 ng/ml) increased effluent and myocardial cAMP levels (P ≤ 0.002). Compared with dobutamine, edema toxin produced similar myocardial changes, but these occurred more slowly and persisted longer. Increases in HR, CF, and cAMP with edema toxin were inhibited by a monoclonal antibody blocking toxin uptake and by adefovir, which inhibits the toxin's intracellular adenyl cyclase activity (P ≤ 0.05). Lethal toxin at an LD(80) dose (50 ng/ml) had no significant effect on heart function but a much higher dose (500 ng/ml) reduced all parameters (P ≤ 0.05). In conclusion, edema toxin produced cAMP-mediated myocardial chronotropic, inotropic, and vasodilatory effects. Vasodilation systemically with edema toxin could contribute to shock during anthrax while masking potential inotropic effects. Although lethal toxin produced myocardial depression, this only occurred at high doses, and its relevance to in vivo findings is unclear.
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Affiliation(s)
- Caitlin W Hicks
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland 20892, USA
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Paccani SR, Benagiano M, Savino MT, Finetti F, Tonello F, D'Elios MM, Baldari CT. The adenylate cyclase toxin of Bacillus anthracis is a potent promoter of T(H)17 cell development. J Allergy Clin Immunol 2011; 127:1635-7. [PMID: 21310477 DOI: 10.1016/j.jaci.2010.12.1104] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2010] [Revised: 12/17/2010] [Accepted: 12/28/2010] [Indexed: 01/09/2023]
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Lee KH, Kim JY, Kim WK, Shin DH, Choi KU, Kim DW, Lee WJ, Choi JH, Lee SH, Kim GH, Song GA, Jeon TY, Kim CD, Hong KW, Park DY. Protective effect of rebamipide against Helicobacter pylori-CagA-induced effects on gastric epithelial cells. Dig Dis Sci 2011; 56:441-8. [PMID: 20556513 DOI: 10.1007/s10620-010-1299-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Accepted: 06/03/2010] [Indexed: 12/28/2022]
Abstract
BACKGROUND Helicobacter pylori CagA dysregulates cell signaling pathways and leads to targeted transcriptional up-regulation of genes implicated in gastric cell injury. The aim of this study was to determine the effects of rebamipide on CagA-induced effects on gastric epithelial cells. We investigated the effects of rebamipide treatment (pre- or post-treatment before or after CagA transfection) on CagA-induced gastric cell injury. METHOD We evaluated the morphologic changes (hummingbird phenotype) associated with ZO-1 mislocalization by confocal microscopy, IL-8 production by ELISA, and NF-κB activation by luciferase assay in AGS gastric epithelial cells and MDCK cells. RESULTS Transfection of CagA into gastric epithelial cells induced morphologic changes (hummingbird phenotype), ZO-1 mislocalization, and IL-8 production in gastric epithelial cells. Pre-treatment with rebamipide inhibits CagA-induced effects on gastric epithelial cells, including morphologic changes (hummingbird phenotype) associated with ZO-1 mislocalization, IL-8 production, and NF-κB activity. CONCLUSIONS These results suggest that rebamipide might have a potential role in the protection of H. pylori CagA-induced effects on gastric epithelial cells.
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Affiliation(s)
- Kyung Hwa Lee
- Department of Pathology, Pusan National University School of Medicine and Pusan National University Hospital, Pusan National University, Seo-Gu, Busan, Republic of Korea
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Kandadi MR, Hua Y, Ma H, Li Q, Kuo SR, Frankel AE, Ren J. Anthrax lethal toxin suppresses murine cardiomyocyte contractile function and intracellular Ca2+ handling via a NADPH oxidase-dependent mechanism. PLoS One 2010; 5:e13335. [PMID: 20967205 PMCID: PMC2954163 DOI: 10.1371/journal.pone.0013335] [Citation(s) in RCA: 25] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Accepted: 09/22/2010] [Indexed: 01/10/2023] Open
Abstract
Objectives Anthrax infection is associated with devastating cardiovascular sequelae, suggesting unfavorable cardiovascular effects of toxins originated from Bacillus anthracis namely lethal and edema toxins. This study was designed to examine the direct effect of lethal toxins on cardiomyocyte contractile and intracellular Ca2+ properties. Methods Murine cardiomyocyte contractile function and intracellular Ca2+ handling were evaluated including peak shortening (PS), maximal velocity of shortening/ relengthening (± dL/dt), time-to-PS (TPS), time-to-90% relengthening (TR90), intracellular Ca2+ rise measured as fura-2 fluorescent intensity (ΔFFI), and intracellular Ca2+ decay rate. Stress signaling and Ca2+ regulatory proteins were assessed using Western blot analysis. Results In vitro exposure to a lethal toxin (0.05 – 50 nM) elicited a concentration-dependent depression on cardiomyocyte contractile and intracellular Ca2+ properties (PS, ± dL/dt, ΔFFI), along with prolonged duration of contraction and intracellular Ca2+ decay, the effects of which were nullified by the NADPH oxidase inhibitor apocynin. The lethal toxin significantly enhanced superoxide production and cell death, which were reversed by apocynin. In vivo lethal toxin exposure exerted similar time-dependent cardiomyocyte mechanical and intracellular Ca2+ responses. Stress signaling cascades including MEK1/2, p38, ERK and JNK were unaffected by in vitro lethal toxins whereas they were significantly altered by in vivo lethal toxins. Ca2+ regulatory proteins SERCA2a and phospholamban were also differentially regulated by in vitro and in vivo lethal toxins. Autophagy was drastically triggered although ER stress was minimally affected following lethal toxin exposure. Conclusions Our findings indicate that lethal toxins directly compromised murine cardiomyocyte contractile function and intracellular Ca2+ through a NADPH oxidase-dependent mechanism.
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Affiliation(s)
- Machender R. Kandadi
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, Wyoming, United States of America
| | - Yinan Hua
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, Wyoming, United States of America
| | - Heng Ma
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, Wyoming, United States of America
| | - Qun Li
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, Wyoming, United States of America
| | - Shu-ru Kuo
- Cancer Research Institute of Scott and White Memorial Hospital, Temple, Texas, United States of America
| | - Arthur E. Frankel
- Cancer Research Institute of Scott and White Memorial Hospital, Temple, Texas, United States of America
| | - Jun Ren
- Center for Cardiovascular Research and Alternative Medicine, University of Wyoming College of Health Sciences, Laramie, Wyoming, United States of America
- * E-mail:
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Gnade BT, Moen ST, Chopra AK, Peterson JW, Yeager LA. Emergence of anthrax edema toxin as a master manipulator of macrophage and B cell functions. Toxins (Basel) 2010; 2:1881-97. [PMID: 22069663 PMCID: PMC3153274 DOI: 10.3390/toxins2071881] [Citation(s) in RCA: 11] [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: 06/18/2010] [Revised: 07/06/2010] [Accepted: 07/12/2010] [Indexed: 11/19/2022] Open
Abstract
Anthrax edema toxin (ET), a powerful adenylyl cyclase, is an important virulence factor of Bacillus anthracis. Until recently, only a modest amount of research was performed to understand the role this toxin plays in the organism's immune evasion strategy. A new wave of studies have begun to elucidate the effects this toxin has on a variety of host cells. While efforts have been made to illuminate the effect ET has on cells of the adaptive immune system, such as T cells, the greatest focus has been on cells of the innate immune system, particularly the macrophage. Here we discuss the immunoevasive activities that ET exerts on macrophages, as well as new research on the effects of this toxin on B cells.
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Affiliation(s)
- Bryan T. Gnade
- Department of Microbiology & Immunology, The University of Texas Medical Branch, Galveston, TX 77555, USA; (B.T.G.); (S.T.M.)
| | - Scott T. Moen
- Department of Microbiology & Immunology, The University of Texas Medical Branch, Galveston, TX 77555, USA; (B.T.G.); (S.T.M.)
| | - Ashok K. Chopra
- Department of Microbiology & Immunology, The University of Texas Medical Branch, Galveston, TX 77555, USA; (B.T.G.); (S.T.M.)
- Center for Biodefense and Emerging Infectious Diseases and Sealy Center for Vaccine Development, The University of Texas Medical Branch, Galveston, TX 77555, USA; (A.K.C.); (J.W.P.)
| | - Johnny W. Peterson
- Department of Microbiology & Immunology, The University of Texas Medical Branch, Galveston, TX 77555, USA; (B.T.G.); (S.T.M.)
- Center for Biodefense and Emerging Infectious Diseases and Sealy Center for Vaccine Development, The University of Texas Medical Branch, Galveston, TX 77555, USA; (A.K.C.); (J.W.P.)
| | - Linsey A. Yeager
- Department of Microbiology & Immunology, The University of Texas Medical Branch, Galveston, TX 77555, USA; (B.T.G.); (S.T.M.)
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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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Raymond B, Batsche E, Boutillon F, Wu YZ, Leduc D, Balloy V, Raoust E, Muchardt C, Goossens PL, Touqui L. Anthrax lethal toxin impairs IL-8 expression in epithelial cells through inhibition of histone H3 modification. PLoS Pathog 2009; 5:e1000359. [PMID: 19343203 PMCID: PMC2655721 DOI: 10.1371/journal.ppat.1000359] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [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: 08/20/2008] [Accepted: 03/02/2009] [Indexed: 12/01/2022] Open
Abstract
Lethal toxin (LT) is a critical virulence factor of Bacillus anthracis, the etiological agent of anthrax, whose pulmonary form is fatal in the absence of treatment. Inflammatory response is a key process of host defense against invading pathogens. We report here that intranasal instillation of a B. anthracis strain bearing inactive LT stimulates cytokine production and polymorphonuclear (PMN) neutrophils recruitment in lungs. These responses are repressed by a prior instillation of an LT preparation. In contrast, instillation of a B. anthracis strain expressing active LT represses lung inflammation. The inhibitory effects of LT on cytokine production are also observed in vitro using mouse and human pulmonary epithelial cells. These effects are associated with an alteration of ERK and p38-MAPK phosphorylation, but not JNK phosphorylation. We demonstrate that although NF-κB is essential for IL-8 expression, LT downregulates this expression without interfering with NF-κB activation in epithelial cells. Histone modifications are known to induce chromatin remodelling, thereby enhancing NF-κB binding on promoters of a subset of genes involved in immune response. We show that LT selectively prevents histone H3 phosphorylation at Ser 10 and recruitment of the p65 subunit of NF-κB at the IL-8 and KC promoters. Our results suggest that B. anthracis represses the immune response, in part by altering chromatin accessibility of IL-8 promoter to NF-κB in epithelial cells. This epigenetic reprogramming, in addition to previously reported effects of LT, may represent an efficient strategy used by B. anthracis for invading the host. Bacillus anthracis, the etiological agent of anthrax, can infect mammals either accidentally or as a potential consequence of a terrorism threat. Pulmonary infection is a life-threatening form of the disease, causing a near 100% mortality rate in the absence of appropriate therapy. Thus, it is important to understand the mechanisms of host defense against B. anthracis. We examined the effects of various B. anthracis strains on lung inflammation in a mouse model of pulmonary anthrax and on human lung epithelial cells, the first barrier of lung against invading pathogens. We showed that a B. anthracis strain expressing lethal toxin inhibits inflammation. In contrast, a strain in which this toxin has been inactivated induces lung inflammation. We next examined the mechanisms involved in the inhibitory effect of lethal toxin. We showed that B. anthracis injects lethal toxin into epithelial cells, blocks the molecules associated on the chromosome, and thus represses production of mediators involved in inflammation. As the latter is a key process in host defense, its alteration by lethal toxin predisposes the host to infection by B. anthracis. This effect on the chromosomal machinery may represent an efficient strategy used by B. anthracis for invading the host.
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Affiliation(s)
- Benoit Raymond
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- Unité Inserm, U.874, Paris, France
| | - Eric Batsche
- Institut Pasteur, Unité de Régulation Epigénétique, Paris, France
| | - Florence Boutillon
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- Unité Inserm, U.874, Paris, France
| | - Yong-Zheng Wu
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- Unité Inserm, U.874, Paris, France
| | - Dominique Leduc
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- Unité Inserm, U.874, Paris, France
| | - Viviane Balloy
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- Unité Inserm, U.874, Paris, France
| | - Eloïse Raoust
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- Unité Inserm, U.874, Paris, France
| | | | - Pierre L. Goossens
- Institut Pasteur, Unité des Toxines et Pathogénie Bactérienne, Paris, France
- CNRS, URA-2172, Paris, France
| | - Lhousseine Touqui
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
- Unité Inserm, U.874, Paris, France
- * E-mail:
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Raymond B, Leduc D, Ravaux L, Le Goffic R, Candela T, Raymondjean M, Goossens PL, Touqui L. Edema toxin impairs anthracidal phospholipase A2 expression by alveolar macrophages. PLoS Pathog 2008; 3:e187. [PMID: 18069891 PMCID: PMC2134952 DOI: 10.1371/journal.ppat.0030187] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [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: 03/30/2007] [Accepted: 10/26/2007] [Indexed: 01/14/2023] Open
Abstract
Bacillus anthracis, the etiological agent of anthrax, is a spore-forming Gram-positive bacterium. Infection with this pathogen results in multisystem dysfunction and death. The pathogenicity of B. anthracis is due to the production of virulence factors, including edema toxin (ET). Recently, we established the protective role of type-IIA secreted phospholipase A2 (sPLA2-IIA) against B. anthracis. A component of innate immunity produced by alveolar macrophages (AMs), sPLA2-IIA is found in human and animal bronchoalveolar lavages at sufficient levels to kill B. anthracis. However, pulmonary anthrax is almost always fatal, suggesting the potential impairment of sPLA2-IIA synthesis and/or action by B. anthracis factors. We investigated the effect of purified ET and ET-deficient B. anthracis strains on sPLA2-IIA expression in primary guinea pig AMs. We report that ET inhibits sPLA2-IIA expression in AMs at the transcriptional level via a cAMP/protein kinase A–dependent process. Moreover, we show that live B. anthracis strains expressing functional ET inhibit sPLA2-IIA expression, whereas ET-deficient strains induced this expression. This stimulatory effect, mediated partly by the cell wall peptidoglycan, can be counterbalanced by ET. We conclude that B. anthracis down-regulates sPLA2-IIA expression in AMs through a process involving ET. Our study, therefore, describes a new molecular mechanism implemented by B. anthracis to escape innate host defense. These pioneering data will provide new molecular targets for future intervention against this deathly pathogen. All mammals are susceptible to infection by Bacillus anthracis, the etiological agent of anthrax. Infection can occur either accidentally or as a potential consequence of a terrorism threat. Pulmonary infection is the most life-threatening form of the disease, causing a near 100% mortality. Despite appropriate therapy, all forms of infection may progress to fatal systemic anthrax, characterized by sepsis and respiratory failure. Thus, it is important to understand the mechanisms of host defense against B. anthracis. We have previously shown that alveolar macrophages produce an enzyme involved in innate defense that can kill B. anthracis: the enzyme is known as secreted phospholipase A2-IIA (sPLA2-IIA). The alveolar macrophage is one of the first cell types to come in contact with B. anthracis. In this study, we show that live B. anthracis spores stimulate the synthesis of sPLA2-IIA, this stimulation being counterbalanced by the inhibitory effect of the edema toxin produced by germinated spores and bacilli. Our study suggests that inhibition of sPLA2-IIA synthesis by edema toxin is a mechanism by which B. anthracis can escape innate host defense. These pioneering data provide new molecular targets for future intervention against this deadly pathogen.
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Affiliation(s)
- Benoit Raymond
- Institut Pasteur, Unité de Défense Innée et Inflammation, Paris, France
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Abstract
The role of the cellular protein LRP6 in anthrax toxin entry is controversial. Previous studies showed that LRP6 was important for efficient intoxication of human M2182 prostate carcinoma cells but other studies performed with cells from gene-knockout mice demonstrated no role for either LRP6 or the related LRP5 protein in anthrax toxin entry. One possible explanation for this discrepancy is that LRP6 may be important for anthrax toxin entry into human, but not mouse, cells. To test this idea we have investigated the effect of knocking down LRP6 or LRP5 expression with siRNAs in human HeLa cells. We show here that efficient knockdown of either LRP6, LRP5, or both proteins has no influence on the kinetics of anthrax lethal toxin entry or MEK1 substrate cleavage in these cells. These data argue against a human-specific role for LRP6 in anthrax toxin entry and suggest instead that involvement of this protein may be restricted to certain cell types independently of their species of origin.
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Affiliation(s)
- Patricia L. Ryan
- Infectious Disease Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America
- Division of Biological Sciences, University of California San Diego, La Jolla, California, United States of America
| | - John A. T. Young
- Infectious Disease Laboratory, The Salk Institute for Biological Studies, La Jolla, California, United States of America
- * E-mail:
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Chapelsky S, Batty S, Frost M, Mogridge J. Inhibition of anthrax lethal toxin-induced cytolysis of RAW264.7 cells by celastrol. PLoS One 2008; 3:e1421. [PMID: 18183301 PMCID: PMC2170518 DOI: 10.1371/journal.pone.0001421] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 12/17/2007] [Indexed: 01/23/2023] Open
Abstract
Background Bacillus anthracis is the bacterium responsible for causing anthrax. The ability of B. anthracis to cause disease is dependent on a secreted virulence factor, lethal toxin, that promotes survival of the bacteria in the host by impairing the immune response. A well-studied effect of lethal toxin is the killing of macrophages, although the molecular mechanisms involved have not been fully characterized. Methodology/Principal Findings Here, we demonstrate that celastrol, a quinone methide triterpene derived from a plant extract used in herbal medicine, inhibits lethal toxin-induced death of RAW264.7 murine macrophages. Celastrol did not prevent cleavage of mitogen activated protein kinase kinase 1, a cytosolic target of the toxin, indicating that it did not inhibit the uptake or catalytic activity of lethal toxin. Surprisingly, celastrol conferred almost complete protection when it was added up to 1.5 h after intoxication, indicating that it could rescue cells in the late stages of intoxication. Since the activity of the proteasome has been implicated in intoxication using other pharmacological agents, we tested whether celastrol blocked proteasome activity. We found that celastrol inhibited the proteasome-dependent degradation of proteins in RAW264.7 cells, but only slightly inhibited proteasome-mediated cleavage of fluorogenic substrates in vitro. Furthermore, celastrol blocked stimulation of IL-18 processing, indicating that celastrol acted upstream of inflammasome activation. Conclusions/Significance This work identifies celastrol as an inhibitor of lethal toxin-mediated macrophage lysis and suggests an inhibitory mechanism involving inhibition of the proteasome pathway.
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Affiliation(s)
- Sarah Chapelsky
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Sarah Batty
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Mia Frost
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Jeremy Mogridge
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- * To whom correspondence should be addressed. E-mail:
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Yan M, Roehrl MH, Basar E, Wang JY. Selection and evaluation of the immunogenicity of protective antigen mutants as anthrax vaccine candidates. Vaccine 2007; 26:947-55. [PMID: 18192092 DOI: 10.1016/j.vaccine.2007.11.087] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [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: 07/30/2007] [Revised: 11/28/2007] [Accepted: 11/29/2007] [Indexed: 11/17/2022]
Abstract
Protective antigen (PA) is a central component of anthrax toxin and a major antigen in anthrax vaccines. However, the use of native PA as a vaccine is not optimal. If administered to people who have been freshly exposed to anthrax, PA may actually aid in anthrax toxin formation and thus may pose a serious safety concern for postexposure vaccination applications. A non-functional PA mutant may be a much safer alternative. To identify an improved anthrax vaccine antigen, we examined four non-functional mutants of PA, each being impaired in a critical step of the cellular intoxication pathway of PA. These mutants were Rec(-) (unable to bind PA-receptors), SSSR (resistant to activation by furin), Oligo(-) (unable to form oligomers), and DNI (Dominant Negative Inhibitory, unable to form endosomal transmembrane pores). When tested in mice and after three doses of immunization, all four mutants were highly potent in eliciting PA-specific, toxin-neutralizing antibodies, with immunogenicity increasing in the order of PA<Rec(-)<SSSR<Oligo(-)<DNI. While the differences between Rec(-) or SSSR and PA were small and not statistically significant, DNI and Oligo(-) were significantly more immunogenic than wild-type PA. One year after immunization and compared with PA-immunized mice, DNI-immunized mice maintained significantly higher levels of anti-PA IgG with correspondingly higher titers of toxin-neutralizing activity. In contrast, Oligo(-)-immunized mice had high levels of anti-PA IgG but lower titers of toxin-neutralizing activity, suggesting that Oligo(-) mutation sites may overlap with critical protective epitopes of PA. Our study demonstrates that PA-based vaccines could be improved both in terms of safety and efficacy by strategic mutations that not only render PA non-functional but also simultaneously enhance its immunogenic potency. Recombinant PA mutants, particularly DNI, hold great promise as better and safer antigens than wild-type PA for use in postexposure vaccination.
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Affiliation(s)
- Ming Yan
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, United States
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Cowan GJM, Atkins HS, Johnson LK, Titball RW, Mitchell TJ. Immunisation with anthrolysin O or a genetic toxoid protects against challenge with the toxin but not against Bacillus anthracis. Vaccine 2007; 25:7197-205. [PMID: 17765365 DOI: 10.1016/j.vaccine.2007.07.040] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2007] [Revised: 07/05/2007] [Accepted: 07/15/2007] [Indexed: 11/18/2022]
Abstract
Anthrolysin O (ALO) is a toxin produced by Bacillus anthracis, the causative agent of anthrax. It is a member of the cholesterol-dependent cytolysin (CDC) group of toxins, many of which are potential vaccine candidates that protect against their producing organisms. Pore formation by ALO was studied by transmission electron microscopy and pores were found to be consistent with those formed by other members of this toxin family. We constructed and characterised a novel genetic toxoid of anthrolysin O, Delta6mALO, which was able to bind to cells but was incapable of pore-formation or haemolysis. The capacity of the haemolytic and non-haemolytic forms of ALO to protect against challenge with the toxin or B. anthracis was determined. Immunisation with both active and non-haemolytic forms of ALO elicited protection against lethal i.v. challenge with ALO but neither was protective against B. anthracis in a murine i.p. challenge model. Immunisation with another CDC, pneumolysin, did not confer cross-protection against challenge with ALO. Histopathological investigation following lethal i.v. challenge with ALO revealed acute pathology in the lungs with occlusion of alveolar vessels by fibrin deposits.
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Affiliation(s)
- Graeme J M Cowan
- Division of Infection and Immunity, Glasgow Biomedical Research Centre, University of Glasgow, Glasgow G12 8TA, UK
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