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Kharga K, Kumar L, Patel SKS. Recent Advances in Monoclonal Antibody-Based Approaches in the Management of Bacterial Sepsis. Biomedicines 2023; 11:biomedicines11030765. [PMID: 36979744 PMCID: PMC10045367 DOI: 10.3390/biomedicines11030765] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/21/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
Sepsis is a life-threatening condition characterized by an uncontrolled inflammatory response to an infectious agent and its antigens. Immune cell activation against the antigens causes severe distress that mediates a strong inflammatory response in vital organs. Sepsis is responsible for a high rate of morbidity and mortality in immunosuppressed patients. Monoclonal antibody (mAb)-based therapeutic strategies are now being explored as a viable therapy option for severe sepsis and septic shock. Monoclonal antibodies may provide benefits through two major strategies: (a) monoclonal antibodies targeting the pathogen and its components, and (b) mAbs targeting inflammatory signaling may directly suppress the production of inflammatory mediators. The major focus of mAb therapies has been bacterial endotoxin (lipopolysaccharide), although other surface antigens are also being investigated for mAb therapy. Several promising candidates for mAbs are undergoing clinical trials at present. Despite several failures and the investigation of novel targets, mAb therapy provides a glimmer of hope for the treatment of severe bacterial sepsis and septic shock. In this review, mAb candidates, their efficacy against controlling infection, with special emphasis on potential roadblocks, and prospects are discussed.
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Affiliation(s)
- Kusum Kharga
- School of Biotechnology, Faculty of Applied Sciences and Biotechnology, Shoolini University, Solan 173229, Himachal Pradesh, India
| | - Lokender Kumar
- School of Biotechnology, Faculty of Applied Sciences and Biotechnology, Shoolini University, Solan 173229, Himachal Pradesh, India
- Cancer Biology Laboratory, Raj Khosla Centre for Cancer Research, Shoolini University, Solan 173229, Himachal Pradesh, India
- Correspondence: (L.K.); (S.K.S.P.)
| | - Sanjay Kumar Singh Patel
- Department of Chemical Engineering, Konkuk University, Seoul 05029, Republic of Korea
- Correspondence: (L.K.); (S.K.S.P.)
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Abstract
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The paradigm of antivirulence
therapy dictates that bacterial pathogens
are specifically disarmed but not killed by neutralizing their virulence
factors. Clearance of the invading pathogen by the immune system is
promoted. As compared to antibiotics, the pathogen-selective antivirulence
drugs hold promise to minimize collateral damage to the beneficial
microbiome. Also, selective pressure for resistance is expected to
be lower because bacterial viability is not directly affected. Antivirulence
drugs are being developed for stand-alone prophylactic and therapeutic
treatments but also for combinatorial use with antibiotics. This Review
focuses on drug modalities that target bacterial exotoxins after the
secretion or release-upon-lysis. Exotoxins have a significant and
sometimes the primary role as the disease-causing virulence factor,
and thereby they are attractive targets for drug development. We describe
the key pre-clinical and clinical trial data that have led to the
approval of currently used exotoxin-targeted drugs, namely the monoclonal
antibodies bezlotoxumab (toxin B/TcdB, Clostridioides difficile), raxibacumab (anthrax toxin, Bacillus anthracis), and obiltoxaximab (anthrax toxin, Bacillus anthracis), but also to challenges with some of the promising leads. We also
highlight the recent developments in pre-clinical research sector
to develop exotoxin-targeted drug modalities, i.e., monoclonal antibodies,
antibody fragments, antibody mimetics, receptor analogs, neutralizing
scaffolds, dominant-negative mutants, and small molecules. We describe
how these exotoxin-targeted drug modalities work with high-resolution
structural knowledge and highlight their advantages and disadvantages
as antibiotic alternatives.
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Affiliation(s)
- Moona Sakari
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, Kiinamyllynkatu 10, FI-20520 Turku, Finland
| | - Arttu Laisi
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, Kiinamyllynkatu 10, FI-20520 Turku, Finland
| | - Arto T. Pulliainen
- Institute of Biomedicine, Research Unit for Infection and Immunity, University of Turku, Kiinamyllynkatu 10, FI-20520 Turku, Finland
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Cui X, Xu W, Neupane P, Weiser-Schlesinger A, Weng R, Pockros B, Li Y, Moayeri M, Leppla SH, Fitz Y, Eichacker PQ. Bacillus anthracis lethal toxin, but not edema toxin, increases pulmonary artery pressure and permeability in isolated perfused rat lungs. Am J Physiol Heart Circ Physiol 2019; 316:H1076-H1090. [PMID: 30767685 DOI: 10.1152/ajpheart.00685.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Although lethal toxin (LT) and edema toxin (ET) contribute to lethality during Bacillus anthracis infection, whether they increase vascular permeability and the extravascular fluid accumulation characterizing this infection is unclear. We employed an isolated perfused Sprague-Dawley rat lung model to investigate LT and ET effects on pulmonary vascular permeability. Lungs (n ≥ 6 per experimental group) were isolated, ventilated, suspended from a force transducer, and perfused. Lung weight and pulmonary artery (Ppa) and left atrial pressures were measured over 4 h, after which pulmonary capillary filtration coefficients (Kf.c) and lung wet-to-dry weight ratios (W/D) were determined. When compared with controls, LT increased Ppa over 4 h and Kf.c and W/D at 4 h (P < 0.0001). ET decreased Ppa in a significant trend (P = 0.09) but did not significantly alter Kf.c or W/D (P ≥ 0.29). Edema toxin actually blocked LT increases in Ppa but not LT increases in Kf.c and W/D. When Ppa was maintained at control levels, LT still increased Kf.c and W/D (P ≤ 0.004). Increasing the dose of each toxin five times significantly increased and a toxin-directed monoclonal antibody decreased the effects of each toxin (P ≤ 0.05). Two rho-kinase inhibitors (GSK269962 and Y27632) decreased LT increases in Ppa (P ≤ 0.02) but actually increased Kf.c and W/D in LT and control lungs (P ≤ 0.05). A vascular endothelial growth factor receptor inhibitor (ZM323881) had no significant effect (P ≥ 0.63) with LT. Thus, LT but not ET can increase pulmonary vascular permeability independent of increased Ppa and could contribute to pulmonary fluid accumulation during anthrax infection. However, pulmonary vascular dilation with ET could disrupt protective hypoxic vasoconstriction. NEW & NOTEWORTHY The most important findings from the present study are that Bacillus anthracis lethal toxin increases pulmonary artery pressure and pulmonary permeability independently in the isolated rat lung, whereas edema toxin decreases the former and does not increase permeability. Each effect could be a basis for organ dysfunction in patients with this lethal infection. These findings further support the need for adjunctive therapies that limit the effects of both toxins during infection.
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Affiliation(s)
- Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Wanying Xu
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Pranita Neupane
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Andie Weiser-Schlesinger
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Ray Weng
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Benjamin Pockros
- 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
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, Maryland
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, Maryland
| | - Yvonne Fitz
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Peter Q Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
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Caldwell M, Hathcock T, Brock KV. Passive protection against anthrax in mice with plasma derived from horses hyper-immunized against Bacillus anthracis Sterne strain. PeerJ 2017; 5:e3907. [PMID: 29259839 PMCID: PMC5733894 DOI: 10.7717/peerj.3907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 09/19/2017] [Indexed: 11/20/2022] Open
Abstract
In this study, equine source polyclonal anti-Bacillus anthracis immunoglobulins were generated and utilized to demonstrate passive protection of mice in a lethal challenge assay. Four horses were hyper-immunized with B. anthracis Sterne strain for approximately one year. The geometric mean anti-PA titer in the horses at maximal response following immunization was 1:77,936 (Log2 mean titer 16.25, SEM ± 0.25 95% CI [15.5 -17.0]). The geometric mean neutralizing titer at maximal response was 1:128 (Log2 mean titer 7, SEM ± 0.0, 95% CI 7). Treatment with hyper-immune plasma or purified immunoglobulins was successful in passively protecting A/J mice from a lethal B. anthracis Sterne strain challenge. The treatment of mice with hyper-immune plasma at time 0 h and 24 h post-infection had no effect on survival, but did significantly increase mean time to death (p < 0.0001). Mice treated with purified immunoglobulins at time 0 h and 24 h post-infection in showed significant increase in survival rate (p < 0.001). Bacterial loads in lung, liver and spleen tissue were also assessed and were not significantly different in mice treated with hyper-immune plasma from placebo treated control mice. Mice treated with purified antibodies demonstrated mean colony forming units/gram tissue fourfold less than mice receiving placebo treatment (p < 0.0001). Immunotherapeutics harvested from horses immunized against B. anthracis Sterne strain represent a rapidly induced, inexpensive and effective expansion to the arsenal of treatments against anthrax.
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Affiliation(s)
- Marc Caldwell
- Department of Pathobiology, Auburn University, Auburn, AL, United States of America
| | - Terri Hathcock
- Department of Pathobiology, Auburn University, Auburn, AL, United States of America
| | - Kenny V. Brock
- Edward Via College of Osteopathic Medicine, Auburn University, Auburn, AL, United States of America
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Suffredini DA, Li Y, Xu W, Moayeri M, Leppla S, Fitz Y, Cui X, Eichacker PQ. Shock and lethality with anthrax edema toxin in rats are associated with reduced arterial responsiveness to phenylephrine and are reversed with adefovir. Am J Physiol Heart Circ Physiol 2017; 313:H946-H958. [PMID: 28887331 DOI: 10.1152/ajpheart.00285.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 08/22/2017] [Accepted: 08/24/2017] [Indexed: 12/18/2022]
Abstract
Although edema toxin (ETx) and lethal toxin (LTx) contribute to Bacillus anthracis shock and lethality, the mechanisms underlying their cardiovascular effects are unclear. We have previously shown that ETx but not LTx inhibited phenylephrine-stimulated contraction of aortic rings prepared from healthy rats and that adefovir, a selective inhibitor of ETx cAMP production, blocked this effect. Here, we examined arterial function in rats that received 24-h ETx or LTx infusions. Compared with control rats, ETx reduced mean arterial pressure (MAP) and survival over 48 h (P ≤ 0.0003) and increased plasma cAMP at 4, 24, and 48 h (P < 0.0001) and nitric oxide (NO) at 24 and 48 h (P ≤ 0.01). Compared with control animals, at 24- and 48-h phenylephrine stimulation of aortic rings from ETx animals produced decreased maximal contractile force (MCF; P = 0.05 and 0.006) and in vivo phenylephrine infusion in ETx animals produced decreased proportional increases in MAP (P < 0.0001 and P = 0.05). In ETx-treated animals, compared with placebo-treated animals, adefovir treatment prevented all lethality (P = 0.01), increased MAP (P ≤ 0.0001), decreased plasma and aortic tissue cAMP at 24 and 48 h, respectively (P ≤ 0.03), and plasma NO at both times (P ≤ 0.004), and increased phenylephrine-stimulated increases in MCF in aortic rings and MAP in vivo at 48 h (P = 0.02). LTx decreased MAP and survival also, but it did not alter the response to phenylephrine of MCF in aortic rings prepared from LTx animals or of MAP in vivo. In conclusion, in rats, hypotension and lethality are associated with reduced arterial contractile function with ETx but not LTx and adefovir improves ETx-induced hypotension and lethality.NEW & NOTEWORTHY The most important aspects of the present study are the findings that 1) in vivo challenge with anthrax edema but not lethal toxin depresses arterial contractile function measured both ex vivo and in vivo and 2) adefovir inhibits the effects of edema toxin on arterial hypotension and improves survival with lethal dose of edema toxin challenge.
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Affiliation(s)
- Dante A Suffredini
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland; and
| | - Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland; and
| | - Wanying Xu
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland; and
| | - Mahtab Moayeri
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Stephen Leppla
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Yvonne Fitz
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland; and
| | - Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland; and
| | - Peter Q Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland; and
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Animal Models for the Pathogenesis, Treatment, and Prevention of Infection by Bacillus anthracis. Microbiol Spectr 2016; 3:TBS-0001-2012. [PMID: 26104551 DOI: 10.1128/microbiolspec.tbs-0001-2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
This article reviews the characteristics of the major animal models utilized for studies on Bacillus anthracis and highlights their contributions to understanding the pathogenesis and host responses to anthrax and its treatment and prevention. Advantages and drawbacks associated with each model, to include the major models (murine, guinea pig, rabbit, nonhuman primate, and rat), and other less frequently utilized models, are discussed. Although the three principal forms of anthrax are addressed, the main focus of this review is on models for inhalational anthrax. The selection of an animal model for study is often not straightforward and is dependent on the specific aims of the research or test. No single animal species provides complete equivalence to humans; however, each species, when used appropriately, can contribute to a more complete understanding of anthrax and its etiologic agent.
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Tsai CW, Morris S. Approval of Raxibacumab for the Treatment of Inhalation Anthrax Under the US Food and Drug Administration "Animal Rule". Front Microbiol 2015; 6:1320. [PMID: 26648915 PMCID: PMC4664625 DOI: 10.3389/fmicb.2015.01320] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 11/09/2015] [Indexed: 12/16/2022] Open
Abstract
On December 14, 2012, the FDA approved Raxibacumab, the first monoclonal antibody product developed under Project BioShield to achieve this milestone, and the first biologic product to be approved through the FDA animal efficacy rule (or “Animal Rule”). Raxibacumab is approved for the treatment of adult and pediatric patients with inhalational anthrax due to Bacillus anthracis in combination with appropriate antibiotic drugs and for prophylaxis of inhalational anthrax when alternative therapies are not available or not appropriate. The developmental process required for approval of Raxibacumab illustrates many of the challenges that product developers may encounter when pursuing approval under the Animal Rule and highlights a number of important regulatory and policy issues.
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Affiliation(s)
- Chia-Wei Tsai
- Biomedical Advanced Research and Development Authority, Office of the Assistant Secretary for Preparedness and Response, U.S. Department of Health and Human Services Washington, DC, USA
| | - Stephen Morris
- BioProtection Systems/NewLink Genetics Corp. Devens, MA, USA
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Abstract
Anthrax is a highly contagious and potentially fatal human disease caused by Bacillus anthracis, an aerobic, Gram-positive, spore-forming rod-shaped bacterium with worldwide distribution as a zoonotic infection in herbivore animals. Bioterrorist attacks with inhalational anthrax have prompted the development of more effective treatments. Antibodies against anthrax toxin have been shown to decrease mortality in animal studies. Raxibacumab is a recombinant human monoclonal antibody developed against inhalational anthrax. The drug received approval after human studies showed its safety and animal studies demonstrated its efficacy for treatment as well as prophylaxis against inhalational anthrax. It works by preventing binding of the protective antigen component of the anthrax toxin to its receptors in host cells, thereby blocking the toxin's deleterious effects. Recently updated therapy guidelines for Bacillus anthracis recommend the use of antitoxin treatment. Raxibacumab is the first monoclonal antitoxin antibody made available that can be used with the antibiotics recommended for treatment of the disease. When exposure is suspected, raxibacumab should be given with anthrax vaccination to augment immunity. Raxibacumab provides additional protection against inhalational anthrax via a mechanism different from that of either antibiotics or active immunization. In combination with currently available and recommended therapies, raxibacumab should reduce the morbidity and mortality of inhalational anthrax.
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Affiliation(s)
- Carlos E Kummerfeldt
- Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Medical University of South Carolina, Charleston, SC, USA
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Bouzianas DG. Potential biological targets ofBacillus anthracisin anti-infective approaches against the threat of bioterrorism. Expert Rev Anti Infect Ther 2014; 5:665-84. [PMID: 17678429 DOI: 10.1586/14787210.5.4.665] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The terrorist attacks of 2001 involving anthrax underscore the imperative that safe and effective medical countermeasures should be readily available. Vaccination appears to be the most effective form of mass protection against a biological attack, but the current vaccines have drawbacks that justify the enormous amount of effort currently being put into developing more effective vaccines and other treatment modalities. After providing a comprehensive overview of the organism Bacillus anthracis as a biological weapon and its pathogenicity, this review briefly summarizes the current knowledge vital to the management of anthrax disease. This knowledge has been acquired since 2001 as a result of the progress on anthrax research and focuses on the possible development of improved human anti-infective strategies targeting B. anthracis spore components, as well as strategies based on host-pathogen interactions.
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Affiliation(s)
- Dimitrios G Bouzianas
- Department of Medical Laboratories, Faculty of Health and Care Professions, University-level Technological Educational Institute of Thessaloniki, Greece.
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Panda G, Basak T, Tanwer P, Sengupta S, dos Santos VAPM, Bhatnagar R. Delineating the effect of host environmental signals on a fully virulent strain of Bacillus anthracis using an integrated transcriptomics and proteomics approach. J Proteomics 2014; 105:242-65. [PMID: 24406299 DOI: 10.1016/j.jprot.2013.12.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 12/18/2013] [Accepted: 12/22/2013] [Indexed: 12/30/2022]
Abstract
UNLABELLED Pathogenic bacteria sense the host environment and regulate expression of virulence-related genes. Environmental signals like temperature, bicarbonate/CO2 and glucose induce toxin production in Bacillus anthracis, but the mechanisms by which these signals contribute to virulence and overall physiological adaptation remains elusive. An integrated, systems level investigation using transcriptomics and iTRAQ-based proteomics was done to assess the effect of temperature, bicarbonate/CO2 and glucose on B. anthracis. Significant changes observed in amino acid, carbohydrate, energy and nucleotide metabolism indicates events of metabolic readjustments by environmental factors. Directed induction of genes involved in polyamine biosynthesis and iron metabolism revealed the redirection of cellular metabolite pool towards iron uptake. Protein levels of glycolytic enzymes, ptsH and Ldh along with transcripts involved in immune evasion (mprF, bNOS, Phospholipases and asnA), cell surface remodeling (rfbABCD, antABCD, and cls) and utilization of lactate (lutABC) and inositol showed constant repression under environmental perturbations. Discrepancies observed in mRNA/protein level of genes involved in glycolysis, protein synthesis, stress response and nucleotide metabolism hinted at the existence of additional regulatory layers and illustrated the utility of an integrated approach. The above findings might assist in the identification of novel adaptive strategies of B. anthracis during host associated survival and pathogenesis. BIOLOGICAL SIGNIFICANCE In this study, the changes observed at both transcript and protein level were quantified and integrated to understand the effect of host environmental factors (host temperature, bicarbonate and glucose) in shaping the physiology and adaptive strategies of a fully virulent strain of B. anthracis for efficient survival and virulence in its host. Perturbations affecting toxin production were found to concordantly affect vital metabolic pathways and several known as well as novel virulence factors. These changes act as a valuable asset for generating testable hypotheses that can be further verified by detailed molecular and mutant studies to identify novel adaptive strategies of B. anthracis during infection. Adaptation of an integrated transcriptomics and proteomics approach also led to the identification of discrepancies between mRNA/protein levels among genes across major functional categories. Few of these discrepancies have been previously reported in literature for model organisms. However their existence in B. anthracis and that too as a result of growth perturbations have not been reported till date. These findings demonstrate a substantial role of regulatory processes post mRNA synthesis via post transcriptional, translational or protein degradation mechanisms. This article is part of a Special Issue entitled: Proteomics of non-model organisms.
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Affiliation(s)
- Gurudutta Panda
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Trayambak Basak
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, 110020, India; Academy of Scientific & Innovative Research, Delhi, India
| | - Pooja Tanwer
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Shantanu Sengupta
- Genomics and Molecular Medicine Unit, CSIR-Institute of Genomics and Integrative Biology, New Delhi, 110020, India; Academy of Scientific & Innovative Research, Delhi, India
| | - Vítor A P Martins dos Santos
- Systems and Synthetic Biology, Wageningen University, Dreijenplein 10, 6703 HB Wageningen, The Netherlands; LifeGlimmer GmbH, Markelstrasse 38, Berlin 12163, Germany
| | - Rakesh Bhatnagar
- Molecular Biology and Genetic Engineering Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi, 110067, India.
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Brojatsch J, Casadevall A, Goldman DL. Molecular determinants for a cardiovascular collapse in anthrax. Front Biosci (Elite Ed) 2014; 6:139-47. [PMID: 24389148 DOI: 10.2741/e697] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Bacillus anthracis releases two bipartite proteins, lethal toxin and edema factor, that contribute significantly to the progression of anthrax-associated shock. As blocking the anthrax toxins prevents disease, the toxins are considered the main virulence factors of the bacterium. The anthrax bacterium and the anthrax toxins trigger multi-organ failure associated with enhanced vascular permeability, hemorrhage and cardiac dysfunction in animal challenge models. A recent study using mice that either lacked the anthrax toxin receptor in specific cells and corresponding mice expressing the receptor in specific cell types demonstrated that cardiovascular cells are critical for disease mediated by anthrax lethal toxin. These studies are consistent with involvement of the cardiovascular system, and with an increase of cardiac failure markers observed in human anthrax and in animal models using B. anthracis and anthrax toxins. This review discusses the current state of knowledge regarding the pathophysiology of anthrax and tries to provide a mechanistic model and molecular determinants for the circulatory shock in anthrax.
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Affiliation(s)
- Jurgen Brojatsch
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY
| | - Arturo Casadevall
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY
| | - David L Goldman
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY
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Kau JH, Shih YL, Lien TS, Lee CC, Huang HH, Lin HC, Sun DS, Chang HH. Activated protein C ameliorates Bacillus anthracis lethal toxin-induced lethal pathogenesis in rats. J Biomed Sci 2012; 19:98. [PMID: 23170801 PMCID: PMC3536616 DOI: 10.1186/1423-0127-19-98] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 10/18/2012] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Lethal toxin (LT) is a major virulence factor of Bacillus anthracis. Sprague Dawley rats manifest pronounced lung edema and shock after LT treatments, resulting in high mortality. The heart failure that is induced by LT has been suggested to be a principal mechanism of lung edema and mortality in rodents. Since LT-induced death occurs more rapidly in rats than in mice, suggesting that other mechanisms in addition to the heart dysfunction may be contributed to the fast progression of LT-induced pathogenesis in rats. Coagulopathy may contribute to circulatory failure and lung injury. However, the effect of LT on coagulation-induced lung dysfunction is unclear. METHODS To investigate the involvement of coagulopathy in LT-mediated pathogenesis, the mortality, lung histology and coagulant levels of LT-treated rats were examined. The effects of activated protein C (aPC) on LT-mediated pathogenesis were also evaluated. RESULTS Fibrin depositions were detected in the lungs of LT-treated rats, indicating that coagulation was activated. Increased levels of plasma D-dimer and thrombomodulin, and the ameliorative effect of aPC further suggested that the activation of coagulation-fibrinolysis pathways plays a role in LT-mediated pathogenesis in rats. Reduced mortality was associated with decreased plasma levels of D-dimer and thrombomodulin following aPC treatments in rats with LT-mediated pathogenesis. CONCLUSIONS These findings suggest that the activation of coagulation in lung tissue contributes to mortality in LT-mediated pathogenesis in rats. In addition, anticoagulant aPC may help to develop a feasible therapeutic strategy.
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Affiliation(s)
- Jyh-Hwa Kau
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan, ROC
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13
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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] [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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14
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Artenstein AW, Opal SM. Novel approaches to the treatment of systemic anthrax. Clin Infect Dis 2012; 54:1148-61. [PMID: 22438345 DOI: 10.1093/cid/cis017] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Anthrax continues to generate concern as an agent of bioterrorism and as a natural cause of sporadic disease outbreaks. Despite the use of appropriate antimicrobial agents and advanced supportive care, the mortality associated with the systemic disease remains high. This is primarily due to the pathogenic exotoxins produced by Bacillus anthracis as well as other virulence factors of the organism. For this reason, new therapeutic strategies that target events in the pathogenesis of anthrax and may potentially augment antimicrobials are being investigated. These include anti-toxin approaches, such as passive immune-based therapies; non-antimicrobial drugs with activity against anthrax toxin components; and agents that inhibit binding, processing, or assembly of toxins. Adjunct therapies that target spore germination or downstream events in anthrax intoxication are also under investigation. In combination, these modalities may enhance the management of systemic anthrax.
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Affiliation(s)
- Andrew W Artenstein
- Center for Biodefense and Emerging Pathogens, Department of Medicine, Memorial Hospital of Rhode Island, Pawtucket, and The Warren Alpert Medical School of Brown University, Providence, RI 02860, USA
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Rogers MS, Cryan LM, Habeshian KA, Bazinet L, Caldwell TP, Ackroyd PC, Christensen KA. A FRET-based high throughput screening assay to identify inhibitors of anthrax protective antigen binding to capillary morphogenesis gene 2 protein. PLoS One 2012; 7:e39911. [PMID: 22768167 PMCID: PMC3386954 DOI: 10.1371/journal.pone.0039911] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 06/03/2012] [Indexed: 11/18/2022] Open
Abstract
Anti-angiogenic therapies are effective for the treatment of cancer, a variety of ocular diseases, and have potential benefits in cardiovascular disease, arthritis, and psoriasis. We have previously shown that anthrax protective antigen (PA), a non-pathogenic component of anthrax toxin, is an inhibitor of angiogenesis, apparently as a result of interaction with the cell surface receptors capillary morphogenesis gene 2 (CMG2) protein and tumor endothelial marker 8 (TEM8). Hence, molecules that bind the anthrax toxin receptors may be effective to slow or halt pathological vascular growth. Here we describe development and testing of an effective homogeneous steady-state fluorescence resonance energy transfer (FRET) high throughput screening assay designed to identify molecules that inhibit binding of PA to CMG2. Molecules identified in the screen can serve as potential lead compounds for the development of anti-angiogenic and anti-anthrax therapies. The assay to screen for inhibitors of this protein–protein interaction is sensitive and robust, with observed Z' values as high as 0.92. Preliminary screens conducted with a library of known bioactive compounds identified tannic acid and cisplatin as inhibitors of the PA-CMG2 interaction. We have confirmed that tannic acid both binds CMG2 and has anti-endothelial properties. In contrast, cisplatin appears to inhibit PA-CMG2 interaction by binding both PA and CMG2, and observed cisplatin anti-angiogenic effects are not mediated by interaction with CMG2. This work represents the first reported high throughput screening assay targeting CMG2 to identify possible inhibitors of both angiogenesis and anthrax intoxication.
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Affiliation(s)
- Michael S. Rogers
- Department of Surgery, Vascular Biology Program, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Lorna M. Cryan
- Department of Surgery, Vascular Biology Program, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Kaiane A. Habeshian
- Department of Surgery, Vascular Biology Program, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Lauren Bazinet
- Department of Surgery, Vascular Biology Program, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Thomas P. Caldwell
- Department of Chemistry, Clemson University, Clemson, South Carolina, United States of America
| | - P. Christine Ackroyd
- Department of Chemistry, Clemson University, Clemson, South Carolina, United States of America
| | - Kenneth A. Christensen
- Department of Chemistry, Clemson University, Clemson, South Carolina, United States of America
- * E-mail:
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Hicks CW, Sweeney DA, Cui X, Li Y, Eichacker PQ. An overview of anthrax infection including the recently identified form of disease in injection drug users. Intensive Care Med 2012; 38:1092-104. [PMID: 22527064 DOI: 10.1007/s00134-012-2541-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 02/14/2012] [Indexed: 02/06/2023]
Abstract
PURPOSE Bacillus anthracis infection (anthrax) can be highly lethal. Two recent outbreaks related to contaminated mail in the USA and heroin in the UK and Europe and its potential as a bioterrorist weapon have greatly increased concerns over anthrax in the developed world. METHODS This review summarizes the microbiology, pathogenesis, diagnosis, and management of anthrax. RESULTS AND CONCLUSIONS Anthrax, a gram-positive bacterium, has typically been associated with three forms of infection: cutaneous, gastrointestinal, and inhalational. However, the anthrax outbreak among injection drug users has emphasized the importance of what is now considered a fourth disease form (i.e., injectional anthrax) that is characterized by severe soft tissue infection. While cutaneous anthrax is most common, its early stages are distinct and prompt appropriate treatment commonly produces a good outcome. However, early symptoms with the other three disease forms can be nonspecific and mistaken for less lethal conditions. As a result, patients with gastrointestinal, inhalational, or injectional anthrax may have advanced infection at presentation that can be highly lethal. Once anthrax is suspected, the diagnosis can usually be made with gram stain and culture from blood or tissue followed by confirmatory testing (e.g., PCR). While antibiotics are the mainstay of anthrax treatment, use of adjunctive therapies such as anthrax toxin antagonists are a consideration. Prompt surgical therapy appears to be important for successful management of injectional anthrax.
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Affiliation(s)
- Caitlin W Hicks
- Cleveland Clinic Lerner College of Medicine, Cleveland, OH 44122, USA
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Barochia AV, Cui X, Sun J, Li Y, Solomon SB, Migone TS, Subramanian GM, Bolmer SD, Eichacker PQ. Protective antigen antibody augments hemodynamic support in anthrax lethal toxin shock in canines. J Infect Dis 2012; 205:818-29. [PMID: 22223857 DOI: 10.1093/infdis/jir834] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Anthrax-associated shock is closely linked to lethal toxin (LT) release and is highly lethal despite conventional hemodynamic support. We investigated whether protective antigen-directed monoclonal antibody (PA-mAb) treatment further augments titrated hemodynamic support. METHODS AND RESULTS Forty sedated, mechanically ventilated, instrumented canines challenged with anthrax LT were assigned to no treatment (controls), hemodynamic support alone (protocol-titrated fluids and norepinephrine), PA-mAb alone (administered at start of LT infusion [0 hours] or 9 or 12 hours later), or both, and observed for 96 hours. Although all 8 controls died, 2 of 8 animals receiving hemodynamic support alone survived (median survival times 65 vs 85 hours, respectively; P = .03). PA-mAb alone at 0 hour improved survival (5 of 5 animals survived), but efficacy decreased progressively with delayed treatment (9 hours, 2 of 3 survived; 12 hours, 0 of 4 survived) (P = .004 comparing survival across treatment times). However, combined treatment increased survival irrespective of PA-mAb administration time (0 hours, 4 of 5 animals; 9 hours, 3 of 3 animals; and 12 hours, 4 of 5 animals survived) (P = .95 comparing treatment times). Compared to hemodynamic support alone, when combined over PA-mAb treatment times (0, 9, and 12 hours), combination therapy produced higher survival (P = .008), central venous pressures, and left ventricular ejection fractions, and lower heart rates, norepinephrine requirements and fluid retention (P ≤ .03). CONCLUSIONS PA-mAb may augment conventional hemodynamic support during anthrax LT-associated shock.
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Affiliation(s)
- Amisha V Barochia
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA.
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18
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Garcia AA, Fels RJ, Mosher LJ, Kenney MJ. Bacillus anthracis lethal toxin alters regulation of visceral sympathetic nerve discharge. J Appl Physiol (1985) 2011; 112:1033-40. [PMID: 22114180 DOI: 10.1152/japplphysiol.01105.2011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bacillus anthracis infection is a pathophysiological condition that is complicated by progressive decreases in mean arterial pressure (MAP). Lethal toxin (LeTx) is central to the pathogenesis of B. anthracis infection, and the sympathetic nervous system plays a critical role in physiological regulation of acute stressors. However, the effect of LeTx on sympathetic nerve discharge (SND), a critical link between central sympathetic neural circuits and MAP regulation, remains unknown. We determined visceral (renal, splenic, and adrenal) SND responses to continuous infusion of LeTx [lethal factor (100 μg/kg) + protective antigen (200 μg/kg) infused at 0.5 ml/h for ≤6 h] and vehicle (infused at 0.5 ml/h) in anesthetized, baroreceptor-intact and baroreceptor (sinoaortic)-denervated (SAD) Sprague-Dawley rats. LeTx infusions produced an initial state of cardiovascular and sympathetic nervous system activation in intact and SAD rats. Subsequent to peak LeTx-induced increases in arterial blood pressure, intact rats demonstrated a marked hypotension that was accompanied by significant reductions in SND (renal and splenic) and heart rate (HR) from peak levels. After peak LeTx-induced pressor and sympathoexcitatory responses in SAD rats, MAP, SND (renal, splenic, and adrenal), and HR were progressively and significantly reduced, supporting the hypothesis that LeTx alters the central regulation of sympathetic nerve outflow. These findings demonstrate that the regulation of visceral SND is altered in a complex manner during continuous anthrax LeTx infusions and suggest that sympathetic nervous system dysregulation may contribute to the marked hypotension accompanying B. anthracis infection.
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Affiliation(s)
- A A Garcia
- Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas 66506, USA
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Differential effects of linezolid and ciprofloxacin on toxin production by Bacillus anthracis in an in vitro pharmacodynamic system. Antimicrob Agents Chemother 2011; 56:513-7. [PMID: 22064542 DOI: 10.1128/aac.05724-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus anthracis causes anthrax. Ciprofloxacin is a gold standard for the treatment of anthrax. Previously, using the non-toxin-producing ΔSterne strain of B. anthracis, we demonstrated that linezolid was equivalent to ciprofloxacin for reducing the total (vegetative and spore) bacterial population. With ciprofloxacin therapy, the total population consisted of spores. With linezolid therapy, the population consisted primarily of vegetative bacteria. Linezolid is a protein synthesis inhibitor, while ciprofloxacin is not. Since toxins are produced only by vegetative B. anthracis, the effect of linezolid and ciprofloxacin on toxin production is of interest. The effect of simulated clinical regimens of ciprofloxacin and linezolid on the vegetative and spore populations and on toxin production was examined in an in vitro pharmacodynamic model over 15 days by using the toxin-producing Sterne strain of B. anthracis. Ciprofloxacin and linezolid reduced the total Sterne population at similar rates. With ciprofloxacin therapy, the total Sterne population consisted of spores. With linezolid therapy, >90% of the population was vegetative B. anthracis. With ciprofloxacin therapy, toxin was first detectable at 3 h and remained detectable for at least 5 h. Toxin was never detected with linezolid therapy. Ciprofloxacin and linezolid reduced the total Sterne population at similar rates. However, the B. anthracis population was primarily spores with ciprofloxacin therapy and was primarily vegetative bacteria with linezolid therapy. Toxin production was detected for at least 5 h with ciprofloxacin therapy but was never detected with linezolid treatment. Linezolid may have an advantage over ciprofloxacin for the treatment of B. anthracis infections.
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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] [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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Altaweel L, Chen Z, Moayeri M, Cui X, Li Y, Su J, Fitz Y, Johnson S, Leppla SH, Purcell R, Eichacker PQ. Delayed treatment with W1-mAb, a chimpanzee-derived monoclonal antibody against protective antigen, reduces mortality from challenges with anthrax edema or lethal toxin in rats and with anthrax spores in mice. Crit Care Med 2011; 39:1439-47. [PMID: 21336113 DOI: 10.1097/ccm.0b013e3182120691] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE W1-mAb is a chimpanzee-derived monoclonal antibody to protective antigen that improved survival when administered before anthrax lethal toxin challenge in rats. To better define W1-mAb's efficacy for anthrax, we administered it after initiation of 24-hr infusions of edema toxin and lethal toxin either alone or together in rats or following anthrax spore challenge in mice. INTERVENTIONS W1-mAb or placebo treatment. METHODS AND MAIN RESULTS In toxin-challenged rats treated with placebo, survival rates were lower with edema toxin (500 μg/kg) compared to lethal toxin either alone (175 μg/kg) or with edema toxin (175 μg/kg each) (8%, 33%, and 32%, respectively), but the median time to death was longer (36, 11, and 9 hrs, respectively) (p ≤ .01 for all comparisons). W1-mAb administered up to 12 hrs after edema toxin and 6 hrs after lethal toxin increased survival and reduced hypotension (p ≤ .01). However, only administration of W1-mAb at 0 hrs improved these variables with lethal toxin and edema toxin together (p ≤ .0002). In C57BL/6J mice challenged with anthrax spores subcutaneously, compared to placebo treatment (0 of 15 animals survived), W1-mAb administered beginning 24 hrs after challenge increased survival (13 of 15 survived) (p ≤ .0001). CONCLUSION While rapidity of lethality may influence the effectiveness of delayed W1-mAb treatment, these rat and mouse studies provide a basis for further exploring this agent's usefulness for anthrax.
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Affiliation(s)
- Laith Altaweel
- Critical Care Medicine Department, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
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Cai C, Che J, Xu L, Guo Q, Kong Y, Fu L, Xu J, Cheng Y, Chen W. Tumor endothelium marker-8 based decoys exhibit superiority over capillary morphogenesis protein-2 based decoys as anthrax toxin inhibitors. PLoS One 2011; 6:e20646. [PMID: 21674060 PMCID: PMC3107238 DOI: 10.1371/journal.pone.0020646] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 05/06/2011] [Indexed: 01/06/2023] Open
Abstract
Anthrax toxin is the major virulence factor produced by Bacillus anthracis. The toxin consists of three protein subunits: protective antigen (PA), lethal factor, and edema factor. Inhibition of PA binding to its receptors, tumor endothelium marker-8 (TEM8) and capillary morphogenesis protein-2 (CMG2) can effectively block anthrax intoxication, which is particularly valuable when the toxin has already been overproduced at the late stage of anthrax infection, thus rendering antibiotics ineffectual. Receptor-like agonists, such as the mammalian cell-expressed von Willebrand factor type A (vWA) domain of CMG2 (sCMG2), have demonstrated potency against the anthrax toxin. However, the soluble vWA domain of TEM8 (sTEM8) was ruled out as an anthrax toxin inhibitor candidate due to its inferior affinity to PA. In the present study, we report that L56A, a PA-binding-affinity-elevated mutant of sTEM8, could inhibit anthrax intoxication as effectively as sCMG2 in Fisher 344 rats. Additionally, pharmacokinetics showed that L56A and sTEM8 exhibit advantages over sCMG2 with better lung-targeting and longer plasma retention time, which may contribute to their enhanced protective ability in vivo. Our results suggest that receptor decoys based on TEM8 are promising anthrax toxin inhibitors and, together with the pharmacokinetic studies in this report, may contribute to the development of novel anthrax drugs.
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Affiliation(s)
- Chenguang Cai
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jinjing Che
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Long Xu
- Laboratory of protein engineering, Beijing Institute of Biotechnology, Beijing, China
| | - Qiang Guo
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yirong Kong
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ling Fu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Junjie Xu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (JX) (JX); (YC) (YC); (WC) (WC)
| | - Yuanguo Cheng
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (JX) (JX); (YC) (YC); (WC) (WC)
| | - Wei Chen
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- * E-mail: (JX) (JX); (YC) (YC); (WC) (WC)
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Fighting bacterial infections—Future treatment options. Drug Resist Updat 2011; 14:125-39. [DOI: 10.1016/j.drup.2011.02.001] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 01/31/2011] [Accepted: 01/31/2011] [Indexed: 12/13/2022]
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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] [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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Passive vaccination with a human monoclonal antibody: generation of antibodies and studies for efficacy in Bacillus anthracis infections. Immunobiology 2010; 216:847-53. [PMID: 21397977 DOI: 10.1016/j.imbio.2010.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 12/04/2010] [Indexed: 11/21/2022]
Abstract
A major difficulty in creating human monoclonal antibodies is the lack of a suitable myeloma cell line to be used for fusion experiments. In order to create fully human monoclonal antibodies for passive immunization, the human mouse heteromyeloma cell line CB-F7 was evaluated. Using this cell line, we generated human monoclonal antibodies against Bacillus anthracis toxin components. Antibodies against protective antigen (PA) and against lethal factor (LF) were obtained using peripheral blood lymphocytes (PBLs) from persons vaccinated with the UK anthrax vaccine. PBL were fused with the cell line CB-F7. We obtained several clones producing PA specific Ig and one clone (hLF1-SAN) producing a monoclonal antibody (hLF1) directed against LF. The LF binding antibody was able to neutralize Anthrax toxin activity in an in vitro neutralization assay, and preliminary in vivo studies in mice also indicated a trend towards protection. We mapped the epitope of the antibody binding to LF by dot blot analysis and ELIFA using 80 synthetic LF peptides of 20 amino acid lengths with an overlapping range of 10 amino acids. Our results suggest the binding of the monoclonal antibody to the peptide regions 121-150 or 451-470 of LF. The Fab-fragment of the antibody hLF1 was cloned in Escherichia coli and could be useful as part of a fully human monoclonal antibody for the treatment of Anthrax infections. In general, our studies show the applicability of the CB-F7 line to create fully human monoclonal antibodies for vaccination.
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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] [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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Bouzianas DG. Current and future medical approaches to combat the anthrax threat. J Med Chem 2010; 53:4305-31. [PMID: 20102155 DOI: 10.1021/jm901024b] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Dimitrios G Bouzianas
- Laboratory of Molecular Endocrinology, Division of Endocrinology and Metabolism, AHEPA University Hospital, 1 S. Kyriakidi Street, P.C. 54636, Thessaloniki, Macedonia, Greece.
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Peterson JW, Moen ST, Healy D, Pawlik JE, Taormina J, Hardcastle J, Thomas JM, Lawrence WS, Ponce C, Chatuev BM, Gnade BT, Foltz SM, Agar SL, Sha J, Klimpel GR, Kirtley ML, Eaves-Pyles T, Chopra AK. Protection Afforded by Fluoroquinolones in Animal Models of Respiratory Infections with Bacillus anthracis, Yersinia pestis, and Francisella tularensis. Open Microbiol J 2010; 4:34-46. [PMID: 21127743 PMCID: PMC2995158 DOI: 10.2174/1874285801004010034] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 04/19/2010] [Accepted: 04/23/2010] [Indexed: 11/28/2022] Open
Abstract
Successful treatment of inhalation anthrax, pneumonic plague and tularemia can be achieved with fluoroquinolone antibiotics, such as ciprofloxacin and levofloxacin, and initiation of treatment is most effective when administered as soon as possible following exposure. Bacillus anthracis Ames, Yersinia pestis CO92, and Francisella tularensis SCHU S4 have equivalent susceptibility in vitro to ciprofloxacin and levofloxacin (minimal inhibitory concentration is 0.03 μg/ml); however, limited information is available regarding in vivo susceptibility of these infectious agents to the fluoroquinolone antibiotics in small animal models. Mice, guinea pig, and rabbit models have been developed to evaluate the protective efficacy of antibiotic therapy against these life-threatening infections. Our results indicated that doses of ciprofloxacin and levofloxacin required to protect mice against inhalation anthrax were approximately 18-fold higher than the doses of levofloxacin required to protect against pneumonic plague and tularemia. Further, the critical period following aerosol exposure of mice to either B. anthracis spores or Y. pestis was 24 h, while mice challenged with F. tularensis could be effectively protected when treatment was delayed for as long as 72 h postchallenge. In addition, it was apparent that prolonged antibiotic treatment was important in the effective treatment of inhalation anthrax in mice, but short-term treatment of mice with pneumonic plague or tularemia infections were usually successful. These results provide effective antibiotic dosages in mice, guinea pigs, and rabbits and lay the foundation for the development and evaluation of combinational treatment modalities.
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Affiliation(s)
- Johnny W Peterson
- Department of Microbiology and Immunology, Galveston National Laboratory, University of Texas Medical Branch, 301 University Blvd. Galveston, Texas 77555-0610
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Abstract
Raxibacumab (ABthrax) is a human IgG1 monoclonal antibody against Bacillus anthracis protective antigen. HGS is currently providing stockpiles of the agent to the US government for use in the prevention and treatment of inhalation anthrax. As of May 2009, the candidate was undergoing review by the US Food and Drug Administration. The availability of bioterrorism countermeasures has become more important since the September 2001 anthrax attacks, and development of raxibacumab is a significant advance in this area.
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Affiliation(s)
- Sohini Mazumdar
- Genetics Graduate Program, Department of Anatomy and Cell Biology, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA, USA.
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Cui X, Su J, Li Y, Shiloach J, Solomon S, Kaufman JB, Mani H, Fitz Y, Weng J, Altaweel L, Besch V, Eichacker PQ. Bacillus anthracis cell wall produces injurious inflammation but paradoxically decreases the lethality of anthrax lethal toxin in a rat model. Intensive Care Med 2009; 36:148-56. [PMID: 19756496 DOI: 10.1007/s00134-009-1643-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 08/03/2009] [Accepted: 08/04/2009] [Indexed: 01/09/2023]
Abstract
OBJECTIVES The in vivo inflammatory effects of the Bacillus anthracis cell wall are unknown. We therefore investigated these effects in rats and, for comparison, those of known inflammatory stimulants, Staphylococcus aureus cell wall or lipopolysaccharide (LPS). METHOD AND RESULTS Sprague-Dawley rats (n = 103) were challenged with increasing B. anthracis cell wall doses (10, 20, 40, 80, or 160 mg/kg) or diluent (control) as a bolus or 24-h infusion. The three highest bolus doses were lethal (20-64% lethality rates) as were the two highest infused doses (13% with each). Comparisons among lethal or nonlethal doses on other measured parameters were not significantly different, and these were combined for analysis. Over the 24 h after challenge initiation with lethal bolus or infusion, compared to controls, ten inflammatory cytokines and NO levels were increased and circulating neutrophils and platelets decreased (P <or= 0.05). Changes with lethal doses were greater than changes with nonlethal doses (P <or= 0.01). Lethal bolus or infusion doses produced hypotension or hypoxemia, respectively (P <or= 0.05). The effects with B. anthracis cell wall were similar to those of S. aureus cell wall or LPS. However, paradoxically administration of B. anthracis cell wall or LPS decreased the lethality of concurrently administered B. anthracis lethal toxin (P < 0.0001 and 0.04, respectively). CONCLUSION B. anthracis cell wall has the potential to produce inflammatory injury during anthrax infection clinically. However, understanding why cell wall or LPS paradoxically reduced lethality with lethal toxin may help understand this toxin's pathogenic effects.
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Affiliation(s)
- Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Building 10, Room 2C148, Bethesda, MD 20892, USA
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Capillary morphogenesis protein-2 is the major receptor mediating lethality of anthrax toxin in vivo. Proc Natl Acad Sci U S A 2009; 106:12424-9. [PMID: 19617532 DOI: 10.1073/pnas.0905409106] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Anthrax toxin, a major virulence factor of Bacillus anthracis, gains entry into target cells by binding to either of 2 von Willebrand factor A domain-containing proteins, tumor endothelium marker-8 (TEM8) and capillary morphogenesis protein-2 (CMG2). The wide tissue expression of TEM8 and CMG2 suggest that both receptors could play a role in anthrax pathogenesis. To explore the roles of TEM8 and CMG2 in normal physiology, as well as in anthrax pathogenesis, we generated TEM8- and CMG2-null mice and TEM8/CMG2 double-null mice by deleting TEM8 and CMG2 transmembrane domains. TEM8 and CMG2 were found to be dispensable for mouse development and life, but both are essential in female reproduction in mice. We found that the lethality of anthrax toxin for mice is mostly mediated by CMG2 and that TEM8 plays only a minor role. This is likely because anthrax toxin has approximately 11-fold higher affinity for CMG2 than for TEM8. Finally, the CMG2-null mice are also shown to be highly resistant to B. anthracis spore infection, attesting to the importance of both anthrax toxin and CMG2 in anthrax infections.
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Migone TS, Subramanian GM, Zhong J, Healey LM, Corey A, Devalaraja M, Lo L, Ullrich S, Zimmerman J, Chen A, Lewis M, Meister G, Gillum K, Sanford D, Mott J, Bolmer SD. Raxibacumab for the treatment of inhalational anthrax. N Engl J Med 2009; 361:135-44. [PMID: 19587338 DOI: 10.1056/nejmoa0810603] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Inhalational anthrax caused by Bacillus anthracis is associated with high mortality primarily due to toxin-mediated injury. Raxibacumab is a human IgG1lambda monoclonal antibody directed against protective antigen, a component of the anthrax toxin. METHODS We evaluated the efficacy of raxibacumab as a prophylactic agent and after disease onset in a total of four randomized, placebo-controlled studies conducted in rabbits and monkeys. Animals were exposed to an aerosolized target exposure of B. anthracis spores that was approximately 100 times (in the prophylactic studies) and 200 times (in the therapeutic-intervention studies) the median lethal dose. In the therapeutic-intervention studies, animals were monitored for the onset of symptoms. Animals with detectable protective antigen in serum, a significant increase in temperature, or both received a single intravenous bolus of placebo or raxibacumab at a dose of either 20 mg per kilogram of body weight or 40 mg per kilogram. The primary end point was survival at day 14 (in rabbits) or at day 28 (in monkeys). Safety studies were conducted with intravenous raxibacumab (40 mg per kilogram) in 333 healthy human volunteers. RESULTS In both rabbits and monkeys, the time to detection of protective antigen correlated with the time to bacteremia (r=0.9, P<0.001). In the therapeutic-intervention studies, the survival rate was significantly higher among rabbits that received raxibacumab at a dose of 40 mg per kilogram (44% [8 of 18]) than among rabbits that received placebo (0% [0 of 18]; P=0.003). Raxibacumab treatment also significantly increased survival in monkeys (64% [9 of 14], vs. 0% [0 of 12] with placebo; P<0.001). In human subjects, intravenous raxibacumab at a dose of 40 mg per kilogram had a half-life of 20 to 22 days and provided a maximum concentration of the drug in excess of levels that are protective in animals. Concentrations of raxibacumab provide a surrogate end point that should be predictive of clinical benefit. CONCLUSIONS A single dose of raxibacumab improved survival in rabbits and monkeys with symptomatic inhalational anthrax. (ClinicalTrials.gov number, NCT00639678.)
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Moayeri M, Crown D, Dorward DW, Gardner D, Ward JM, Li Y, Cui X, Eichacker P, Leppla SH. The heart is an early target of anthrax lethal toxin in mice: a protective role for neuronal nitric oxide synthase (nNOS). PLoS Pathog 2009; 5:e1000456. [PMID: 19478875 PMCID: PMC2680977 DOI: 10.1371/journal.ppat.1000456] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 04/29/2009] [Indexed: 01/04/2023] Open
Abstract
Anthrax lethal toxin (LT) induces vascular insufficiency in experimental animals through unknown mechanisms. In this study, we show that neuronal nitric oxide synthase (nNOS) deficiency in mice causes strikingly increased sensitivity to LT, while deficiencies in the two other NOS enzymes (iNOS and eNOS) have no effect on LT-mediated mortality. The increased sensitivity of nNOS-/- mice was independent of macrophage sensitivity to toxin, or cytokine responses, and could be replicated in nNOS-sufficient wild-type (WT) mice through pharmacological inhibition of the enzyme with 7-nitroindazole. Histopathological analyses showed that LT induced architectural changes in heart morphology of nNOS-/- mice, with rapid appearance of novel inter-fiber spaces but no associated apoptosis of cardiomyocytes. LT-treated WT mice had no histopathology observed at the light microscopy level. Electron microscopic analyses of LT-treated mice, however, revealed striking pathological changes in the hearts of both nNOS-/- and WT mice, varying only in severity and timing. Endothelial/capillary necrosis and degeneration, inter-myocyte edema, myofilament and mitochondrial degeneration, and altered sarcoplasmic reticulum cisternae were observed in both LT-treated WT and nNOS-/- mice. Furthermore, multiple biomarkers of cardiac injury (myoglobin, cardiac troponin-I, and heart fatty acid binding protein) were elevated in LT-treated mice very rapidly (by 6 h after LT injection) and reached concentrations rarely reported in mice. Cardiac protective nitrite therapy and allopurinol therapy did not have beneficial effects in LT-treated mice. Surprisingly, the potent nitric oxide scavenger, carboxy-PTIO, showed some protective effect against LT. Echocardiography on LT-treated mice indicated an average reduction in ejection fraction following LT treatment in both nNOS-/- and WT mice, indicative of decreased contractile function in the heart. We report the heart as an early target of LT in mice and discuss a protective role for nNOS against LT-mediated cardiac damage.
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Affiliation(s)
- Mahtab Moayeri
- Bacterial Toxins and Therapeutics Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Devorah Crown
- Bacterial Toxins and Therapeutics Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - David W. Dorward
- Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Don Gardner
- Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Jerrold M. Ward
- Infectious Diseases Pathogenesis Section, Comparative Medicine Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Yan Li
- Critical Care Medicine Department, National Institutes of Health Clinical Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Xizhong Cui
- Critical Care Medicine Department, National Institutes of Health Clinical Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Peter Eichacker
- Critical Care Medicine Department, National Institutes of Health Clinical Center, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Stephen H. Leppla
- Bacterial Toxins and Therapeutics Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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McGowen AL, Hale LP, Shelburne CP, Abraham SN, Staats HF. The mast cell activator compound 48/80 is safe and effective when used as an adjuvant for intradermal immunization with Bacillus anthracis protective antigen. Vaccine 2009; 27:3544-52. [PMID: 19464533 DOI: 10.1016/j.vaccine.2009.03.069] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 03/20/2009] [Accepted: 03/24/2009] [Indexed: 11/18/2022]
Abstract
We evaluated the safety and efficacy of the mast cell activator compound 48/80 (C48/80) when used as an adjuvant delivered intradermally (ID) with recombinant anthrax protective antigen (rPA) in comparison with two well-known adjuvants. Mice were vaccinated in the ear pinnae with rPA or rPA+C48/80, CpG oligodeoxynucleotides (CpG), or cholera toxin (CT). All adjuvants induced similar increases in serum anti-rPA IgG and lethal toxin neutralizing antibodies. C48/80 induced a balanced cytokine production (Th1/Th2/Th17) by antigen-restimulated splenocytes, minimal injection site inflammation, and no antigen-specific IgE. Histological analysis demonstrated that vaccination with C48/80 reduced the number of resident mast cells and induced an injection site neutrophil influx within 24h. Our data demonstrate that C48/80 is a safe and effective adjuvant, when used by the intradermal route, to induce protective antibody and balanced Th1/Th2/Th17 responses.
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Affiliation(s)
- Afton L McGowen
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
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35
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Norepinephrine in anthrax-associated shock: Even worse than figs?*. Crit Care Med 2009; 37:1510-3. [DOI: 10.1097/ccm.0b013e31819d2c2c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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36
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Li Y, Cui X, Su J, Haley M, Macarthur H, Sherer K, Moayeri M, Leppla SH, Fitz Y, Eichacker PQ. Norepinephrine increases blood pressure but not survival with anthrax lethal toxin in rats. Crit Care Med 2009; 37:1348-54. [PMID: 19242337 PMCID: PMC3401929 DOI: 10.1097/ccm.0b013e31819cee38] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
OBJECTIVES The response of anthrax lethal toxin (LeTx) induced shock and lethality to conventional therapies has received little study. Previously, fluids worsened outcome in LeTx-challenged rats in contrast to its benefit with lipopolysaccharide (LPS) or Escherichia coli. The current study investigated norepinephrine treatment. MEASUREMENTS AND MAIN RESULTS Sprague-Dawley rats (n = 232) weighing between 230 and 250 g were challenged with similar lethal (80%) 24-hour infusions of either LPS or LeTx, or with diluent only. Toxin-challenged animals were also randomized to receive 24-hour infusions with one of three doses of norepinephrine (0.03, 0.3, or 3.0 microg/kg/min) or placebo started 1 hour after initiation of challenge. All toxin animals received similar volumes of fluid over the 24 hours (equivalent to 4.0-4.3 mL/kg/hr). Although the intermediate norepinephrine dose (0.3 microg/kg/min for 24 hours) improved survival with LPS (p = 0.04) and increased blood pressure before the onset of lethality with LeTx (p < 0.0001), it did not improve survival with the latter (p = ns). Furthermore, neither increasing nor decreasing norepinephrine doses improved survival with LeTx. CONCLUSION Hypotension with LeTx may not be a primary cause of lethality in this model. Rather, LeTx may cause direct cellular injury insensitive to vasopressors. These findings suggest that during anthrax infection and shock, along with hemodynamic support, toxin-directed treatments may be necessary as well.
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Affiliation(s)
- Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892
| | - Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892
| | - Junwu Su
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892
| | - Michael Haley
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892
- Carolinas Medical Center, Department of Internal Medicine, Charlotte, NC 28232
| | - Heather Macarthur
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, MO 63104
| | - Kevin Sherer
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892
| | - Mahtab Moayeri
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Stephen H. Leppla
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Yvonne Fitz
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892
| | - Peter Q. Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892
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Crystal structure of the engineered neutralizing antibody M18 complexed to domain 4 of the anthrax protective antigen. J Mol Biol 2009; 387:680-93. [PMID: 19361425 DOI: 10.1016/j.jmb.2009.02.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Revised: 02/03/2009] [Accepted: 02/03/2009] [Indexed: 11/24/2022]
Abstract
The virulence of Bacillus anthracis is critically dependent on the cytotoxic components of the anthrax toxin, lethal factor (LF) and edema factor (EF). LF and EF gain entry into host cells through interactions with the protective antigen (PA), which binds to host cellular receptors such as CMG2. Antibodies that neutralize PA have been shown to confer protection in animal models and are undergoing intense clinical development. A murine monoclonal antibody, 14B7, has been reported to interact with domain 4 of PA (PAD4) and block its binding to CMG2. More recently, the 14B7 antibody was used as the platform for the selection of very high affinity, single-chain antibodies that have tremendous potential as a combination anthrax prophylactic and treatment. Here, we report the high-resolution X-ray structures of three high-affinity, single-chain antibodies in the 14B7 family; 14B7 and two high-affinity variants 1H and M18. In addition, we present the first neutralizing antibody-PA structure, M18 in complex with PAD4 at 3.8 A resolution. These structures provide insights into the mechanism of neutralization, and the effect of various mutations on antibody affinity, and enable a comparison between the binding of the M18 antibody and CMG2 with PAD4.
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Frankel AE, Kuo SR, Dostal D, Watson L, Duesbery NS, Cheng CP, Cheng HJ, Leppla SH. Pathophysiology of anthrax. Front Biosci (Landmark Ed) 2009; 14:4516-24. [PMID: 19273366 DOI: 10.2741/3544] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Infection by Bacillus anthracis in animals and humans results from accidental or intentional exposure, by oral, cutaneous or pulmonary routes, to spores, which are normally present in the soil. Treatment includes administration of antibiotics, vaccination or treatment with antibody to the toxin. A better understanding of the molecular basis of the processes involved in the pathogenesis of anthrax namely, spore germination in macrophages and biological effects of the secreted toxins on heart and blood vessels will lead to improved management of infected animals and patients. Controlling germination will be feasible by inhibiting macrophage paralysis and cell death. On the other hand, the control of terminal hypotension might be achieved by inhibition of cardiomyocyte mitogen-activated protein kinase and stimulation of vessel cAMP.
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Chung MC, Jorgensen SC, Popova TG, Bailey CL, Popov SG. Neutrophil elastase and syndecan shedding contribute to antithrombin depletion in murine anthrax. ACTA ACUST UNITED AC 2008; 54:309-18. [DOI: 10.1111/j.1574-695x.2008.00480.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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40
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Chang HH, Lo SJ. RHODOSTOMIN, A SNAKE VENOM DISINTEGRIN, SERVED AS A MOLECULAR TOOL TO DISSECT THE INTEGRIN FUNCTION. TOXIN REV 2008. [DOI: 10.1080/15569540701209823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Hu WG, Yin J, Jager S, Wong C, Fulton C, Rayner GA, Aw C, Fisher GR, Dai X, Nagata LP. A Novel Approach to Development of Monoclonal Antibodies Using Native Antigen for Immunization and Recombinant Antigen for Screening. Hybridoma (Larchmt) 2008; 27:307-11. [DOI: 10.1089/hyb.2008.0011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Wei-Gang Hu
- Defence Research and Development Canada-Suffield, Medicine Hat, Alberta, Canada
| | - Junfei Yin
- Canada West Biosciences Inc., Camrose, Alberta, Canada
| | - Scott Jager
- Defence Research and Development Canada-Suffield, Medicine Hat, Alberta, Canada
| | - Christina Wong
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Courtney Fulton
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - George A. Rayner
- Defence Research and Development Canada-Suffield, Medicine Hat, Alberta, Canada
| | - Connie Aw
- Canada West Biosciences Inc., Camrose, Alberta, Canada
| | - Glen R. Fisher
- Defence Research and Development Canada-Suffield, Medicine Hat, Alberta, Canada
| | - Xiaojiang Dai
- Defence Research and Development Canada-Suffield, Medicine Hat, Alberta, Canada
| | - Les P. Nagata
- Defence Research and Development Canada-Suffield, Medicine Hat, Alberta, Canada
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Cao S, Liu Z, Guo A, Li Y, Zhang C, Gaobing W, Chunfang F, Tan Y, Chen H. Efficient production and characterization of Bacillus anthracis lethal factor and a novel inactive mutant rLFm-Y236F. Protein Expr Purif 2008; 59:25-30. [PMID: 18276157 DOI: 10.1016/j.pep.2007.12.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2007] [Revised: 12/24/2007] [Accepted: 12/31/2007] [Indexed: 11/17/2022]
Abstract
Lethal factor (LF) is a 90kDa zinc metalloprotease that plays an important role in the virulence of anthrax. Recombinant LF (rLF) is an effective tool to study anthrax pathogenesis and treatment. In this study, the LF gene was cloned into the Escherichia coli expression vector pGEX-6P-1 and expressed as a GST fusion protein (GST-rLF) in E. coli BL21-codonPlus (DE3)-RIL cells with 0.2mM IPTG induction at 28 degrees C. The GST-rLF protein was purified and the GST-tag was then cleaved in a single step by combining both GST-affinity column and treatment with 3C protease. This procedure yielded 5mg of rLF protein per liter of culture. The purified rLF was functional as confirmed by cytotoxicity assay in RAW264.7 cells and Western blot assay. Furthermore, the rLF could induce strong immune response in BALB/c mice and the presence of a specific antiserum could neutralize the cytotoxicity of rLF in vitro. In addition, a novel inactive mutant (rLFm-Y236F) was obtained. Compared to the wild-type rLF, an increase by 3700 folds of the purified rLFm-Y236F was needed to achieve a similar level of cytotoxicity of the wild-type rLF. This mutant might be of significance in the study of anthrax pathogenesis and treatment.
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Affiliation(s)
- Sha Cao
- National Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
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Kuo SR, Willingham MC, Bour SH, Andreas EA, Park SK, Jackson C, Duesbery NS, Leppla SH, Tang WJ, Frankel AE. Anthrax toxin-induced shock in rats is associated with pulmonary edema and hemorrhage. Microb Pathog 2007; 44:467-72. [PMID: 18222626 DOI: 10.1016/j.micpath.2007.12.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2007] [Revised: 12/01/2007] [Accepted: 12/07/2007] [Indexed: 12/23/2022]
Abstract
Bacillus anthracis infections are frequently associated with severe and often irreversible hypotensive shock despite appropriate antibiotics and aggressive hemodynamic and pulmonary support. Based on the observations that the anthrax secreted proteins-protective antigen (PA), lethal factor (LF), and edema factor (EF) also produce shock and mortality in animal models, we chose to characterize further the clinical chemistries and microscopic pathology of toxin treated rats. Groups of three male Sprague Dawley rats received bolus intravenous infusions of PA/LF, PA/EF, LF, or EF alone and blood samples and tissues were collected and assayed for chemistries and tissue pathology. In PA/LF and PA/EF treated animals but not other groups, chemistries showed transaminasemia and elevated lactate dehydrogenase. PA/LF treated animals alone showed elevated hemoglobin and hematocrits; PA/EF treated animals alone showed lymphopenia. Pathology was remarkable for pulmonary edema in PA/LF treated rat lungs and pulmonary hemorrhage in PA/EF treated rat lungs. These results are consistent with our and others' previous findings that the morbidity and mortality associated with anthrax are not cytokine-mediated but due to a direct effect of the toxins on the cardiovascular system along with toxin-specific alterations in blood counts. PA/LF pathology matches that seen with acute cardiac failure, and PA/EF pathology coincides with direct vascular endothelial injury. These observations provide a rational basis for drug interventions to reduce the effect of these toxins on the heart and blood vessels.
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Affiliation(s)
- Shu-Ru Kuo
- Cancer Research Institute, Scott & White Memorial Hospital,Temple, TX 76502, USA
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Staats HF, Alam SM, Scearce RM, Kirwan SM, Zhang JX, Gwinn WM, Haynes BF. In vitro and in vivo characterization of anthrax anti-protective antigen and anti-lethal factor monoclonal antibodies after passive transfer in a mouse lethal toxin challenge model to define correlates of immunity. Infect Immun 2007; 75:5443-52. [PMID: 17709410 PMCID: PMC2168269 DOI: 10.1128/iai.00529-07] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Passive transfer of antibody may be useful for preexposure prophylaxis against biological agents used as weapons of terror, such as Bacillus anthracis. Studies were performed to evaluate the ability of anthrax antiprotective antigen (anti-PA) and antilethal factor (anti-LF) neutralizing monoclonal antibodies (mAbs) to protect against an anthrax lethal toxin (LeTx) challenge in a mouse model and to identify correlates of immunity to LeTx challenge. Despite having similar affinities for their respective antigens, anti-PA (3F11) and anti-LF (9A11), passive transfer of up to 1.5 mg of anti-PA 3F11 mAb did not provide significant protection when transferred to mice 24 h before LeTx challenge, while passive transfer of as low as 0.375 mg of anti-LF 9A11 did provide significant protection. Serum collected 24 h after passive transfer had LeTx-neutralizing activity when tested using a standard LeTx neutralization assay, but neutralization titers measured using this assay did not correlate with protection against LeTx challenge. However, measurement of LeTx-neutralizing serum responses with an LeTx neutralization assay in vitro employing the addition of LeTx to J774A.1 cells 15 min before the addition of the serum did result in neutralization titers that correlated with protection against LeTx challenge. Our results demonstrate that only the LeTx neutralization titers measured utilizing the addition of LeTx to J774A.1 cells 15 min before the addition of sample correlated with protection in vivo. Thus, this LeTx neutralization assay may be a more biologically relevant neutralization assay to predict the in vivo protective capacity of LeTx-neutralizing antibodies.
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Affiliation(s)
- Herman F Staats
- Department of Pathology, Box 3712, DUMC, Durham, NC 27710, USA.
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Sherer K, Li Y, Cui X, Li X, Subramanian M, Laird MW, Moayeri M, Leppla SH, Fitz Y, Su J, Eichacker PQ. Fluid support worsens outcome and negates the benefit of protective antigen-directed monoclonal antibody in a lethal toxin-infused rat Bacillus anthracis shock model. Crit Care Med 2007; 35:1560-7. [PMID: 17452924 DOI: 10.1097/01.ccm.0000266535.95770.a2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The aim of this study was to test the effects of normal saline treatment either alone or in combination with protective antigen-directed monoclonal antibody in a lethal toxin-infused rat model of anthrax sepsis. DESIGN Prospective controlled animal study. SETTING Animal research laboratory. SUBJECTS Sprague-Dawley rats (n = 539). INTERVENTIONS We initially tested the efficacy of three normal saline doses (5, 10, or 20 mL/kg/hr intravenously for 24 hrs) or none (controls) started when rats were treated with either lethal toxin (24-hr infusion) or, for comparison, lipopolysaccharide (24-hr infusion) or Escherichia coli (intravenous bolus). We then investigated delaying normal saline for 6 hrs or combining it with protective antigen-directed monoclonal antibody following lethal toxin challenge. MEASUREMENTS AND MAIN RESULTS Dose did not alter the effects of normal saline with any challenge (p not significant for all) or when combined with protective antigen-directed monoclonal antibody, so this variable was averaged in analysis. In initial studies, normal saline decreased mortality (mean hazards ratio of survival +/- SE) significantly with E. coli challenge (-0.66 +/- 0.25, p = .009 averaged over normal saline dose) but not lipopolysaccharide (-0.17 +/- 0.20). In contrast, normal saline increased mortality significantly with lethal toxin (0.69 +/- 0.20, p = .001) in a pattern different from E. coli and lipopolysaccharide (p <or= .002 for each). In subsequent studies, normal saline alone once again increased mortality (0.8 +/- 0.3, p = .006), protective antigen-directed monoclonal antibody alone reduced it (-1.7 +/- 0.8, p = .03), and the combination had intermediate effects that were not significant (0.04 +/- 0.3). CONCLUSIONS These findings raise the possibility that normal saline treatment may actually worsen outcome with anthrax lethal toxin. Furthermore, lethal toxin-directed therapies may not be as beneficial when used in combination with this type of fluid support.
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Affiliation(s)
- Kevin Sherer
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, MD, USA
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Li Y, Sherer K, Cui X, Eichacker PQ. New insights into the pathogenesis and treatment of anthrax toxin-induced shock. Expert Opin Biol Ther 2007; 7:843-54. [PMID: 17555370 DOI: 10.1517/14712598.7.6.843] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Inhalational Bacillus anthracis infection is a leading bioterrorist health threat in the US today. Lethal (LeTx) and edema toxin production are key to the virulent effects of this lethal bacteria. Recent insights into the structure and function of these toxins have increased the understanding of both the pathogenesis and treatment of anthrax. These are binary type toxins comprised of protective antigen necessary for their cellular uptake and either lethal or edema factors, the toxigenic moieties. Primary cellular receptors for protective antigen have been identified and the processing of the completed toxins clarified. Consistent with the ability of lethal factor to cleave mitogen activated protein kinase kinases, the evidence indicates that an excessive inflammatory response does not contribute to shock with LeTx. Rather, the immunosuppressive effects of LeTx could promote infection; however, direct endothelial dysfunction may have an important role in shock due to LeTx. Recent studies show that edema factor, a potent adenyl cyclase, may have a major role in shock during anthrax and that it may also be immunosuppresive. Therapies under development which target several steps in the cellular uptake and function of these two toxins have been effective in both in vitro and in vivo systems. Understanding how best to apply these agents in combination with conventional treatments should be a goal of future research.
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MESH Headings
- Adenylyl Cyclases/immunology
- Adenylyl Cyclases/metabolism
- Animals
- Anthrax/complications
- Anthrax/drug therapy
- Anthrax/metabolism
- Anthrax Vaccines/therapeutic use
- Antibodies, Monoclonal/therapeutic use
- Antigens, Bacterial/immunology
- Antigens, Bacterial/metabolism
- Bacillus anthracis/immunology
- Bacillus anthracis/metabolism
- Bacillus anthracis/pathogenicity
- Bacterial Toxins/immunology
- Bacterial Toxins/metabolism
- Endothelium, Vascular/microbiology
- Endothelium, Vascular/physiopathology
- Humans
- Receptors, Peptide/metabolism
- Shock, Septic/drug therapy
- Shock, Septic/metabolism
- Shock, Septic/microbiology
- Shock, Septic/physiopathology
- Virulence
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Affiliation(s)
- Yan Li
- National Institutes of Health, Critical Care Medicine Department, Clinical Center, Bethesda, MD 20892, USA
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Watson LE, Kuo SR, Katki K, Dang T, Park SK, Dostal DE, Tang WJ, Leppla SH, Frankel AE. Anthrax toxins induce shock in rats by depressed cardiac ventricular function. PLoS One 2007; 2:e466. [PMID: 17520025 PMCID: PMC1867860 DOI: 10.1371/journal.pone.0000466] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Accepted: 05/01/2007] [Indexed: 12/05/2022] Open
Abstract
Anthrax infections are frequently associated with severe and often irreversible hypotensive shock. The isolated toxic proteins of Bacillus anthracis produce a non-cytokine-mediated hypotension in rats by unknown mechanisms. These observations suggest the anthrax toxins have direct cardiovascular effects. Here, we characterize these effects. As a first step, we administered systemically anthrax lethal toxin (LeTx) and edema toxin (EdTx) to cohorts of three to twelve rats at different doses and determined the time of onset, degree of hypotension and mortality. We measured serum concentrations of the protective antigen (PA) toxin component at various time points after infusion. Peak serum levels of PA were in the µg/mL range with half-lives of 10–20 minutes. With doses that produced hypotension with delayed lethality, we then gave bolus intravenous infusions of toxins to groups of four to six instrumented rats and continuously monitored blood pressure by telemetry. Finally, the same doses used in the telemetry experiments were given to additional groups of four rats, and echocardiography was performed pretreatment and one, two, three and twenty-four hours post-treatment. LeTx and EdTx each produced hypotension. We observed a doubling of the velocity of propagation and 20% increases in left ventricular diastolic and systolic areas in LeTx-treated rats, but not in EdTx-treated rats. EdTx-but not LeTx-treated rats showed a significant increase in heart rate. These results indicate that LeTx reduced left ventricular systolic function and EdTx reduced preload. Uptake of toxins occurs readily into tissues with biological effects occurring within minutes to hours of serum toxin concentrations in the µg/mL range. LeTx and EdTx yield an irreversible shock with subsequent death. These findings should provide a basis for the rational design of drug interventions to reduce the dismal prognosis of systemic anthrax infections.
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Affiliation(s)
- Linley E. Watson
- Division of Cardiology, Scott and White Memorial Hospital, Scott, Sherwood and Brindley Foundation, Temple, Texas, United States of America
- Department of Medicine, Texas A&M University System, Health Science Center College of Medicine, Temple, Texas, United States of America
- Division of Molecular Cardiology, Texas A&M University System, Health Science Center College of Medicine, and Central Texas Veterans Health Care System, Temple, Texas, United States of America
| | - Shu-ru Kuo
- Scott and White Cancer Research Institute, Temple, Texas, United States of America
| | - Khurshed Katki
- Department of Medicine, Texas A&M University System, Health Science Center College of Medicine, Temple, Texas, United States of America
| | - Tongyun Dang
- Scott and White Cancer Research Institute, Temple, Texas, United States of America
| | - Seong Kyu Park
- Scott and White Cancer Research Institute, Temple, Texas, United States of America
| | - David E. Dostal
- Department of Medicine, Texas A&M University System, Health Science Center College of Medicine, Temple, Texas, United States of America
- Division of Molecular Cardiology, Texas A&M University System, Health Science Center College of Medicine, and Central Texas Veterans Health Care System, Temple, Texas, United States of America
| | - Wei-Jen Tang
- Ben May Institute for Cancer Research, The University of Chicago, Chicago, Illinois, United States of America
| | - Stephen H. Leppla
- Bacterial Toxins and Therapeutics Section, National Institutes of Allergy and Infectious Diseases, Bethesda, Maryland, United States of America
| | - Arthur E. Frankel
- Department of Medicine, Texas A&M University System, Health Science Center College of Medicine, Temple, Texas, United States of America
- Scott and White Cancer Research Institute, Temple, Texas, United States of America
- * To whom correspondence should be addressed. E-mail:
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Sherer K, Li Y, Cui X, Eichacker PQ. Lethal and edema toxins in the pathogenesis of Bacillus anthracis septic shock: implications for therapy. Am J Respir Crit Care Med 2006; 175:211-21. [PMID: 17095744 PMCID: PMC2176088 DOI: 10.1164/rccm.200608-1239cp] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Recent research regarding the structure and function of Bacillus anthracis lethal (LeTx) and edema (ETx) toxins provides growing insights into the pathophysiology and treatment of shock with this lethal bacteria. These are both binary-type toxins composed of protective antigen necessary for their cellular uptake and either lethal or edema factors, the toxigenic moieties. The primary cellular receptors for protective antigen have been identified and constructed and key steps in the extracellular processing and internalization of the toxins clarified. Consistent with the lethal factor's primary action as an intracellular endopeptidase targeting mitogen-activated protein kinase kinases, growing evidence indicates that shock with this toxin does not result from an excessive inflammatory response. In fact, the potent immunosuppressive effects of LeTx may actually contribute to the establishment and persistence of infection. Instead, shock with LeTx may be related to the direct injurious effects of lethal factor on endothelial cell function. Despite the importance of LeTx, very recent studies show that edema factor, a potent adenyl cyclase, has the ability to make a substantial contribution to shock caused by B. anthracis and works additively with LeTx. Furthermore, ETx may contribute to the immunosuppressive effects of LeTx. Therapies under development that target several different steps in the cellular uptake and function of these two toxins have been effective in in vitro and in vivo systems. Understanding how best to apply these agents clinically and how they interact with conventional treatments should be goals for future research.
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Affiliation(s)
- Kevin Sherer
- Critical Care Medicine Department, National Institutes of Health, Bethesda, MD 20892, USA
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Keitel WA. Recombinant protective antigen 102 (rPA102): profile of a second-generation anthrax vaccine. Expert Rev Vaccines 2006; 5:417-30. [PMID: 16989623 DOI: 10.1586/14760584.5.4.417] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Recent terrorist attacks involving the use of Bacillus anthracis spores have stimulated interest in the development of new vaccines for anthrax prevention. Studies of the pathogenesis of anthrax and of the immune responses following infection and immunization underscore the pivotal role that antibodies to the protective antigen play in protection. The most promising vaccine candidates contain purified recombinant protective antigen. Clinical trials of one of these, recombinant protective antigen (rPA)102, are underway. Initial results suggest that rPA102 is well tolerated and immunogenic. Additional trials are necessary to identify optimal formulations and immunization regimens for pre- and postexposure prophylaxis. Future licensure of these and other candidate vaccines will depend on their safety and immunogenicity profiles in humans, and their ability to confer protection in animal models of inhalational anthrax.
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Affiliation(s)
- Wendy A Keitel
- Baylor College of Medicine, Molecular Virology & Microbiology & Medicine, Room 221 D One Baylor Plaza, Houston, TX 77030, USA.
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50
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Zhang J, Xu J, Li G, Dong D, Song X, Guo Q, Zhao J, Fu L, Chen W. The 2β2–2β3 loop of anthrax protective antigen contains a dominant neutralizing epitope. Biochem Biophys Res Commun 2006; 341:1164-71. [PMID: 16460675 DOI: 10.1016/j.bbrc.2006.01.080] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2006] [Accepted: 01/19/2006] [Indexed: 10/25/2022]
Abstract
Anthrax toxin consists of three proteins, protective antigen (PA), lethal factor, and edema factor. PA is the major component in the current anthrax vaccine, but the antigenic epitopes on it are not well-defined. We generated a pool of toxin-neutralizing anti-PA monoclonal antibodies (MAbs) to analyze the neutralizing epitopes of PA. Nine toxin-neutralizing MAbs obtained were found bound to three different domains of PA respectively, among which three MAbs with the strongest toxin-neutralizing activity recognized the same epitope within domain 2. This epitope was fine mapped to the chymotrypsin-sensitive site, (312)SFFD(315), in the 2beta(2)-2beta(3) loop of PA, using phage-displayed random peptide libraries and mutation analysis. The result demonstrated for the first time that the 2beta(2)-2beta(3) loop, which is involved in the transition of PA oligomers from prepore to pore, contains a dominant neutralizing epitope. This work contributes to the immunological and functional analysis of PA and offers perspective for the development of a new epitope vaccine against anthrax.
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Affiliation(s)
- Jun Zhang
- Department of Applied Molecular Biology, State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, 20 Dongdajie, Fengtai, Beijing 100071, China
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