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Bothra A, Perry ML, Wei E, Moayeri M, Ma Q, Biamonte MA, Siirin M, Leppla SH. S9.6-based hybrid capture immunoassay for pathogen detection. Sci Rep 2023; 13:22562. [PMID: 38110611 PMCID: PMC10728093 DOI: 10.1038/s41598-023-49881-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 12/13/2023] [Indexed: 12/20/2023] Open
Abstract
The detection of pathogens is critical for clinical diagnosis and public health surveillance. Detection is usually done with nucleic acid-based tests (NATs) and rapid antigen tests (e.g., lateral flow assays [LFAs]). Although NATs are more sensitive and specific, their use is often limited in resource-poor settings due to specialized requirements. To address this limitation, we developed a rapid DNA-RNA Hybrid Capture immunoassay (HC) that specifically detects RNA from pathogens. This assay utilizes a unique monoclonal antibody, S9.6, which binds DNA-RNA hybrids. Biotinylated single-stranded DNA probes are hybridized to target RNAs, followed by hybrid capture on streptavidin and detection with S9.6. The HC-ELISA assay can detect as few as 104 RNA molecules that are 2.2 kb in length. We also adapted this assay into a LFA format, where captured Bacillus anthracis rpoB RNA of 3.5 kb length was detectable from a bacterial load equivalent to 107 CFU per 100 mg of mouse tissue using either HC-ELISA or HC-LFA. Importantly, we also demonstrated the versatility of HC by detecting other pathogens, including SARS-CoV-2 and Toxoplasma gondii, showing its potential for broad pathogen detection. Notably, HC does not require amplification of the target nucleic acid and utilizes economical formats like ELISA and LFA, making it suitable for use in sentinel labs for pathogen detection or as a molecular tool in basic research laboratories. Our study highlights the potential of HC as a sensitive and versatile method for RNA-based pathogen detection.
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Affiliation(s)
- Ankur Bothra
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA.
| | - Megan L Perry
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Elena Wei
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Qian Ma
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | | | - Marina Siirin
- Drugs and Diagnostics for Tropical Diseases, San Diego, CA, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
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2
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Abstract
Diagnosis of infectious agents is increasingly done by the detection of unique nucleic acid sequences, typically using methods such as PCR that specifically amplify these sequences. A largely neglected alternative approach is to use antibodies that recognize nucleic acids. The unique monoclonal antibody S9.6 recognizes DNA-RNA hybrids in a largely sequence-independent manner. S9.6 has been used in several cases for the analysis of nucleic acids. Extending our recent determination of the structure of S9.6 Fab bound to a DNA-RNA hybrid, we have developed reagents and methods for the sensitive detection of specific DNA and RNA sequences. To facilitate the use in diagnostics, we conjugated the S9.6 Fab to the highly active and well-characterized reporter enzyme human-secreted embryonic alkaline phosphatase (SEAP). Two approaches were utilized for conjugation. The first used sortase A (SrtA), which generates a covalent peptide bond between short amino acid sequences added to recombinantly produced S9.6 Fab and SEAP. The second approach was to genetically fuse the S9.6 Fab and SEAP so that the two are produced as a single molecule. Using these two antibody-SEAP proteins, we developed a simplified ELISA format for the identification of synthetic DNA-RNA hybrids, which can be optimized for detecting nucleic acids of pathogens, as well as for other applications. We successfully used this immunosorbent assay, HC-S, to identify DNA-RNA hybrids in solution with high specificity and sensitivity.
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Affiliation(s)
- Elena Wei
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda Maryland 20892, United States
| | - Charles Bou-Nader
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, United States
| | - Megan L Perry
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda Maryland 20892, United States
| | - Rasem Fattah
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda Maryland 20892, United States
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, United States
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda Maryland 20892, United States
| | - Ankur Bothra
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda Maryland 20892, United States
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3
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Zuo Z, Liu J, Sun Z, Silverstein R, Zou M, Finkel T, Bugge TH, Leppla SH, Liu S. A potent tumor-selective ERK pathway inactivator with high therapeutic index. PNAS Nexus 2022; 1:pgac104. [PMID: 35899070 PMCID: PMC9308561 DOI: 10.1093/pnasnexus/pgac104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 06/28/2022] [Indexed: 02/05/2023]
Abstract
FDA-approved BRAF and MEK small molecule inhibitors have demonstrated some level of efficacy in patients with metastatic melanomas. However, these "targeted" therapeutics have a very low therapeutic index, since these agents affect normal cells, causing undesirable, even fatal, side effects. To address these significant drawbacks, here, we have reengineered the anthrax toxin-based protein delivery system to develop a potent, tumor-selective MEK inactivator. This toxin-based MEK inactivator exhibits potent activity against a wide range of solid tumors, with the highest activity seen when directed toward tumors containing the BRAFV600E mutation. We demonstrate that this reengineered MEK inactivator also exhibits an extremely high therapeutic index (>15), due to its in vitro and in vivo activity being strictly dependent on the expression of multiple tumor-associated factors including tumor-associated proteases matrix metalloproteinase, urokinase plasminogen activator, and anthrax toxin receptor capillary morphogenesis protein-2. Furthermore, we have improved the specificity of this MEK inactivator, restricting its enzymatic activity to only target the ERK pathway, thereby greatly diminishing off-target toxicity. Together, these data suggest that engineered bacterial toxins can be modified to have significant in vitro and in vivo therapeutic effects with high therapeutic index.
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Affiliation(s)
| | | | - Zhihao Sun
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA
| | - Rachel Silverstein
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA
| | - Meijuan Zou
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA
| | - Toren Finkel
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA,Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Thomas H Bugge
- Proteases and Tissue Remodeling Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shihui Liu
- To whom correspondence should be addressed:
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4
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Bou-Nader C, Bothra A, Garboczi DN, Leppla SH, Zhang J. Structural basis of R-loop recognition by the S9.6 monoclonal antibody. Nat Commun 2022; 13:1641. [PMID: 35347133 PMCID: PMC8960830 DOI: 10.1038/s41467-022-29187-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 03/02/2022] [Indexed: 12/31/2022] Open
Abstract
R-loops are ubiquitous, dynamic nucleic-acid structures that play fundamental roles in DNA replication and repair, chromatin and transcription regulation, as well as telomere maintenance. The DNA-RNA hybrid–specific S9.6 monoclonal antibody is widely used to map R-loops. Here, we report crystal structures of a S9.6 antigen-binding fragment (Fab) free and bound to a 13-bp hybrid duplex. We demonstrate that S9.6 exhibits robust selectivity in binding hybrids over double-stranded (ds) RNA and in categorically rejecting dsDNA. S9.6 asymmetrically recognizes a compact epitope of two consecutive RNA nucleotides via their 2′-hydroxyl groups and six consecutive DNA nucleotides via their backbone phosphate and deoxyribose groups. Recognition is mediated principally by aromatic and basic residues of the S9.6 heavy chain, which closely track the curvature of the hybrid minor groove. These findings reveal the molecular basis for S9.6 recognition of R-loops, detail its binding specificity, identify a new hybrid-recognition strategy, and provide a framework for S9.6 protein engineering. The S9.6 monoclonal antibody is widely used to map R-loops genome wide. Here, Bou-Nader et al., define the nucleic acid-binding specificity of S9.6 and report its crystal structures free and bound to a hybrid, which reveal the asymmetric recognition of the RNA and DNA strands and its A-form conformation.
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Affiliation(s)
- Charles Bou-Nader
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA
| | - Ankur Bothra
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, 20892, USA
| | - David N Garboczi
- Structural Biology Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD, 20892, USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, 20892, USA.
| | - Jinwei Zhang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA.
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5
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Yang NJ, Isensee J, Neel DV, Quadros AU, Zhang HXB, Lauzadis J, Liu SM, Shiers S, Belu A, Palan S, Marlin S, Maignel J, Kennedy-Curran A, Tong VS, Moayeri M, Röderer P, Nitzsche A, Lu M, Pentelute BL, Brüstle O, Tripathi V, Foster KA, Price TJ, Collier RJ, Leppla SH, Puopolo M, Bean BP, Cunha TM, Hucho T, Chiu IM. Anthrax toxins regulate pain signaling and can deliver molecular cargoes into ANTXR2 + DRG sensory neurons. Nat Neurosci 2021; 25:168-179. [PMID: 34931070 DOI: 10.1038/s41593-021-00973-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 11/01/2021] [Indexed: 11/09/2022]
Abstract
Bacterial products can act on neurons to alter signaling and function. In the present study, we found that dorsal root ganglion (DRG) sensory neurons are enriched for ANTXR2, the high-affinity receptor for anthrax toxins. Anthrax toxins are composed of protective antigen (PA), which binds to ANTXR2, and the protein cargoes edema factor (EF) and lethal factor (LF). Intrathecal administration of edema toxin (ET (PA + EF)) targeted DRG neurons and induced analgesia in mice. ET inhibited mechanical and thermal sensation, and pain caused by formalin, carrageenan or nerve injury. Analgesia depended on ANTXR2 expressed by Nav1.8+ or Advillin+ neurons. ET modulated protein kinase A signaling in mouse sensory and human induced pluripotent stem cell-derived sensory neurons, and attenuated spinal cord neurotransmission. We further engineered anthrax toxins to introduce exogenous protein cargoes, including botulinum toxin, into DRG neurons to silence pain. Our study highlights interactions between a bacterial toxin and nociceptors, which may lead to the development of new pain therapeutics.
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Affiliation(s)
- Nicole J Yang
- Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Jörg Isensee
- Translational Pain Research, Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Dylan V Neel
- Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Andreza U Quadros
- Center for Research in Inflammatory Diseases, Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | | | - Justas Lauzadis
- Department of Anesthesiology, Stony Brook Medicine, Stony Brook, NY, USA
| | | | - Stephanie Shiers
- Department of Neuroscience, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, USA
| | - Andreea Belu
- Translational Pain Research, Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | | | | | | | | | - Victoria S Tong
- Department of Immunology, Harvard Medical School, Boston, MA, USA
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Pascal Röderer
- Institute of Reconstructive Neurobiology, University of Bonn Medical Faculty and University Hospital Bonn, Bonn, Germany.,Cellomics Unit, LIFE & BRAIN GmbH, Bonn, Germany
| | - Anja Nitzsche
- Institute of Reconstructive Neurobiology, University of Bonn Medical Faculty and University Hospital Bonn, Bonn, Germany.,Cellomics Unit, LIFE & BRAIN GmbH, Bonn, Germany
| | - Mike Lu
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bradley L Pentelute
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA.,The Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Center for Environmental Health Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Oliver Brüstle
- Institute of Reconstructive Neurobiology, University of Bonn Medical Faculty and University Hospital Bonn, Bonn, Germany
| | | | | | - Theodore J Price
- Department of Neuroscience, Center for Advanced Pain Studies, University of Texas at Dallas, Richardson, TX, USA
| | - R John Collier
- Department of Microbiology, Harvard Medical School, Boston, MA, USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Michelino Puopolo
- Department of Anesthesiology, Stony Brook Medicine, Stony Brook, NY, USA
| | - Bruce P Bean
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Thiago M Cunha
- Center for Research in Inflammatory Diseases, Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Tim Hucho
- Translational Pain Research, Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Isaac M Chiu
- Department of Immunology, Harvard Medical School, Boston, MA, USA.
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6
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Yamini G, Kanchi S, Kalu N, Momben Abolfath S, Leppla SH, Ayappa KG, Maiti PK, Nestorovich EM. Hydrophobic Gating and 1/ f Noise of the Anthrax Toxin Channel. J Phys Chem B 2021; 125:5466-5478. [PMID: 34015215 DOI: 10.1021/acs.jpcb.0c10490] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
"Pink" or 1/f noise is a natural phenomenon omnipresent in physics, economics, astrophysics, biology, and even music and languages. In electrophysiology, the stochastic activity of a number of biological ion channels and artificial nanopores could be characterized by current noise with a 1/f power spectral density. In the anthrax toxin channel (PA63), it appears as fast voltage-independent current interruptions between conducting and nonconducting states. This behavior hampers potential development of PA63 as an ion-channel biosensor. On the bright side, the PA63 flickering represents a mesmerizing phenomenon to investigate. Notably, similar 1/f fluctuations are observed in the channel-forming components of clostridial binary C2 and iota toxins, which share functional and structural similarities with the anthrax toxin channel. Similar to PA63, they are evolved to translocate the enzymatic components of the toxins into the cytosol. Here, using high-resolution single-channel lipid bilayer experiments and all-atom molecular dynamic simulations, we suggest that the 1/f noise in PA63 occurs as a result of "hydrophobic gating" at the ϕ-clamp region, the phenomenon earlier observed in several water-filled channels "fastened" inside by the hydrophobic belts. The ϕ-clamp is a narrow "hydrophobic ring" in the PA63 lumen formed by seven or eight phenylalanine residues at position 427, conserved in the C2 and iota toxin channels, which catalyzes protein translocation. Notably, the 1/f noise remains undetected in the F427A PA63 mutant. This finding can elucidate the functional purpose of 1/f noise and its possible role in the transport of the enzymatic components of binary toxins.
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Affiliation(s)
- Goli Yamini
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, Washington D.C., 20064, United States
| | - Subbarao Kanchi
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru 560012, India.,Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bengaluru 560012, India
| | - Nnanya Kalu
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, Washington D.C., 20064, United States
| | - Sanaz Momben Abolfath
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, Washington D.C., 20064, United States
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - K Ganapathy Ayappa
- Department of Chemical Engineering, Indian Institute of Science, Bengaluru 560012, India
| | - Prabal K Maiti
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bengaluru 560012, India
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Avenue, Washington D.C., 20064, United States
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7
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Worthy HL, Williamson LJ, Auhim HS, Leppla SH, Sastalla I, Jones DD, Rizkallah PJ, Berry C. The Crystal Structure of Bacillus cereus HblL 1. Toxins (Basel) 2021; 13:253. [PMID: 33807365 PMCID: PMC8065917 DOI: 10.3390/toxins13040253] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/26/2021] [Accepted: 03/29/2021] [Indexed: 02/07/2023] Open
Abstract
The Hbl toxin is a three-component haemolytic complex produced by Bacillus cereus sensu lato strains and implicated as a cause of diarrhoea in B. cereus food poisoning. While the structure of the HblB component of this toxin is known, the structures of the other components are unresolved. Here, we describe the expression of the recombinant HblL1 component and the elucidation of its structure to 1.36 Å. Like HblB, it is a member of the alpha-helical pore-forming toxin family. In comparison to other members of this group, it has an extended hydrophobic beta tongue region that may be involved in pore formation. Molecular docking was used to predict possible interactions between HblL1 and HblB, and suggests a head to tail dimer might form, burying the HblL1 beta tongue region.
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Affiliation(s)
- Harley L. Worthy
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
- The Henry Wellcome Building for Biocatalysis, Exeter University, Stocker Road, Exeter EX4 4QD, UK
| | - Lainey J. Williamson
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
| | - Husam Sabah Auhim
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
- Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq
| | - Stephen H. Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA; (S.H.L.); (I.S.)
| | - Inka Sastalla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA; (S.H.L.); (I.S.)
- Scientific Review Program, Division of Extramural Activities, NIAID, NIH, Rockville, MD 20892, USA
| | - D. Dafydd Jones
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
| | | | - Colin Berry
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AX, UK; (H.L.W.); (L.J.W.); (H.S.A.); (D.D.J.)
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8
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Cui X, Wang J, Li Y, Couse ZG, Risoleo TF, Moayeri M, Leppla SH, Malide D, Yu ZX, Eichacker PQ. Bacillus anthracis edema toxin inhibits hypoxic pulmonary vasoconstriction via edema factor and cAMP-mediated mechanisms in isolated perfused rat lungs. Am J Physiol Heart Circ Physiol 2021; 320:H36-H51. [PMID: 33064559 PMCID: PMC7847081 DOI: 10.1152/ajpheart.00362.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 10/15/2020] [Accepted: 10/15/2020] [Indexed: 12/31/2022]
Abstract
Bacillus anthracis edema toxin (ET) inhibited lethal toxin-stimulated pulmonary artery pressure (Ppa) and increased lung cAMP levels in our previous study. We therefore examined whether ET inhibits hypoxic pulmonary vasoconstriction (HPV). Following baseline hypoxic measures in isolated perfused lungs from healthy rats, compared with diluent, ET perfusion reduced maximal Ppa increases (mean ± SE percentage of maximal Ppa increase with baseline hypoxia) during 6-min hypoxic periods (FIO2 = 0%) at 120 min (16 ± 6% vs. 51 ± 6%, P = 0.004) and 180 min (11.4% vs. 55 ± 6%, P = 0.01). Protective antigen-mAb (PA-mAb) and adefovir inhibit host cell edema factor uptake and cAMP production, respectively. In lungs perfused with ET following baseline measures, compared with placebo, PA-mAb treatment increased Ppa during hypoxia at 120 and 180 min (56 ± 6% vs. 10 ± 4% and 72 ± 12% vs. 12 ± 3%, respectively, P ≤ 0.01) as did adefovir (84 ± 10% vs. 16.8% and 123 ± 21% vs. 26 ± 11%, respectively, P ≤ 0.01). Compared with diluent, lung perfusion with ET for 180 min reduced the slope of the relationships between Ppa and increasing concentrations of endothelin-1 (ET-1) (21.12 ± 2.96 vs. 3.00 ± 0.76 × 108 cmH2O/M, P < 0.0001) and U46619, a thromboxane A2 analogue (7.15 ± 1.01 vs. 3.74 ± 0.31 × 107 cmH2O/M, P = 0.05) added to perfusate. In lungs isolated from rats after 15 h of in vivo infusions with either diluent, ET alone, or ET with PA-mAb, compared with diluent, the maximal Ppa during hypoxia and the slope of the relationship between change in Ppa and ET-1 concentration added to the perfusate were reduced in lungs from animals challenged with ET alone (P ≤ 0.004) but not with ET and PA-mAb together (P ≥ 0.73). Inhibition of HPV by ET could aggravate hypoxia during anthrax pulmonary infection.NEW & NOTEWORTHY The most important findings here are edema toxin's potent adenyl cyclase activity can interfere with hypoxic pulmonary vasoconstriction, an action that could worsen hypoxemia during invasive anthrax infection with lung involvement. These findings, coupled with other studies showing that lethal toxin can disrupt pulmonary vascular integrity, indicate that both toxins can contribute to pulmonary pathophysiology during infection. In combination, these investigations provide a further basis for the use of antitoxin therapies in patients with worsening invasive anthrax disease.
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Affiliation(s)
- Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Jeffrey Wang
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Zoe G Couse
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Thomas F Risoleo
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
| | - Daniela Malide
- National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Zu-Xi Yu
- National Heart, Lung, and Blood Institute, Bethesda, Maryland
| | - Peter Q Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland
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9
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Greaney AJ, Portley MK, O’Mard D, Crown D, Maier NK, Mendenhall MA, Mayer-Barber KD, Leppla SH, Moayeri M. Frontline Science: Anthrax lethal toxin-induced, NLRP1-mediated IL-1β release is a neutrophil and PAD4-dependent event. J Leukoc Biol 2020; 108:773-786. [PMID: 32421904 PMCID: PMC11062252 DOI: 10.1002/jlb.4hi0320-028r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/17/2020] [Accepted: 03/28/2020] [Indexed: 12/21/2022] Open
Abstract
Anthrax lethal toxin (LT) is a protease that activates the NLRP1b inflammasome sensor in certain rodent strains. Unlike better-studied sensors, relatively little is known about the priming requirements for NLRP1b. In this study, we investigate the rapid and striking priming-independent LT-induced release of IL-1β in mice within hours of toxin challenge. We find IL-1β release to be a NLRP1b- and caspase-1-dependent, NLRP3 and caspase-11-independent event that requires both neutrophils and peptidyl arginine deiminiase-4 (PAD4) activity. The simultaneous LT-induced IL-18 response is neutrophil-independent. Bone marrow reconstitution experiments in mice show toxin-induced IL-1β originates from hematopoietic cells. LT treatment of neutrophils in vitro did not induce IL-1β, neutrophil extracellular traps (NETs), or pyroptosis. Although platelets interact closely with neutrophils and are also a potential source of IL-1β, they were unable to bind or endocytose LT and did not secrete IL-1β in response to the toxin. LT-treated mice had higher levels of cell-free DNA and HMGB1 in circulation than PBS-treated controls, and treatment of mice with recombinant DNase reduced the neutrophil- and NLRP1-dependent IL-1β release. DNA sensor AIM2 deficiency, however, did not impact IL-1β release. These data, in combination with the findings on PAD4, suggest a possible role for in vivo NETs or cell-free DNA in cytokine induction in response to LT challenge. Our findings suggest a complex interaction of events and/or mediators in LT-treated mice with the neutrophil as a central player in induction of a profound and rapid inflammatory response to toxin.
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MESH Headings
- Adaptor Proteins, Signal Transducing/deficiency
- Adaptor Proteins, Signal Transducing/physiology
- Animals
- Anthrax/immunology
- Antigens, Bacterial/pharmacology
- Antigens, Bacterial/toxicity
- Apoptosis Regulatory Proteins/deficiency
- Apoptosis Regulatory Proteins/physiology
- Bacillus anthracis/pathogenicity
- Bacillus anthracis/physiology
- Bacterial Toxins/pharmacology
- Bacterial Toxins/toxicity
- Extracellular Traps/physiology
- Inflammasomes/physiology
- Interleukin-1beta/metabolism
- Mice
- Mice, 129 Strain
- Mice, Congenic
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, SCID
- Monocytes/drug effects
- Monocytes/physiology
- NLR Family, Pyrin Domain-Containing 3 Protein/deficiency
- Neutrophils/drug effects
- Neutrophils/metabolism
- Protein-Arginine Deiminase Type 4/deficiency
- Protein-Arginine Deiminase Type 4/physiology
- Pyroptosis/drug effects
- Radiation Chimera
- Species Specificity
- Spores, Bacterial
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Affiliation(s)
- Allison J. Greaney
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Makayla K. Portley
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Danielle O’Mard
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Devorah Crown
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Nolan K. Maier
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Megan A. Mendenhall
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Katrin D. Mayer-Barber
- Inflammation and Innate Immunity Unit, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen H. Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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10
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Liu J, Zuo Z, Sastalla I, Liu C, Jang JY, Sekine Y, Li Y, Pirooznia M, Leppla SH, Finkel T, Liu S. Sequential CRISPR-Based Screens Identify LITAF and CDIP1 as the Bacillus cereus Hemolysin BL Toxin Host Receptors. Cell Host Microbe 2020; 28:402-410.e5. [PMID: 32544461 DOI: 10.1016/j.chom.2020.05.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/16/2020] [Accepted: 05/15/2020] [Indexed: 12/18/2022]
Abstract
Bacteria and their toxins are associated with significant human morbidity and mortality. While a few bacterial toxins are well characterized, the mechanism of action for most toxins has not been elucidated, thereby limiting therapeutic advances. One such example is the highly potent pore-forming toxin, hemolysin BL (HBL), produced by the gram-positive pathogen Bacillus cereus. However, how HBL exerts its effects and whether it requires any host factors is unknown. Here, we describe an unbiased genome-wide CRISPR-Cas9 knockout screen that identified LPS-induced TNF-α factor (LITAF) as the HBL receptor. Using LITAF-deficient cells, a second, subsequent whole-genome CRISPR-Cas9 screen identified the LITAF-like protein CDIP1 as a second, alternative receptor. We generated LITAF-deficient mice, which exhibit marked resistance to lethal HBL challenges. This work outlines and validates an approach to use iterative genome-wide CRISPR-Cas9 screens to identify the complement of host factors exploited by bacterial toxins to exert their myriad biological effects.
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Affiliation(s)
- Jie Liu
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA; Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Zehua Zuo
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA
| | - Inka Sastalla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Chengyu Liu
- Transgenic Core Facility, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ji Yong Jang
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA
| | - Yusuke Sekine
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA
| | - Yuesheng Li
- DNA Sequencing and Genomics Core Facility, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mehdi Pirooznia
- Bioinformatics and Computational Biology Core Facility, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Toren Finkel
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA; Division of Cardiology, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Shihui Liu
- Aging Institute of University of Pittsburgh and University of Pittsburgh Medical Center, Pittsburgh, PA 15219, USA; Division of Infectious Diseases, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA.
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11
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Fox D, Mathur A, Xue Y, Liu Y, Tan WH, Feng S, Pandey A, Ngo C, Hayward JA, Atmosukarto II, Price JD, Johnson MD, Jessberger N, Robertson AAB, Burgio G, Tscharke DC, Fox EM, Leyton DL, Kaakoush NO, Märtlbauer E, Leppla SH, Man SM. Bacillus cereus non-haemolytic enterotoxin activates the NLRP3 inflammasome. Nat Commun 2020; 11:760. [PMID: 32029733 PMCID: PMC7005308 DOI: 10.1038/s41467-020-14534-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 01/14/2020] [Indexed: 02/07/2023] Open
Abstract
Inflammasomes are important for host defence against pathogens and homeostasis with commensal microbes. Here, we show non-haemolytic enterotoxin (NHE) from the neglected human foodborne pathogen Bacillus cereus is an activator of the NLRP3 inflammasome and pyroptosis. NHE is a non-redundant toxin to haemolysin BL (HBL) despite having a similar mechanism of action. Via a putative transmembrane region, subunit C of NHE initiates binding to the plasma membrane, leading to the recruitment of subunit B and subunit A, thus forming a tripartite lytic pore that is permissive to efflux of potassium. NHE mediates killing of cells from multiple lineages and hosts, highlighting a versatile functional repertoire in different host species. These data indicate that NHE and HBL operate synergistically to induce inflammation and show that multiple virulence factors from the same pathogen with conserved function and mechanism of action can be exploited for sensing by a single inflammasome.
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Affiliation(s)
- Daniel Fox
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Anukriti Mathur
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Yansong Xue
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Yunqi Liu
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Wei Hong Tan
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Shouya Feng
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Abhimanu Pandey
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Chinh Ngo
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Jenni A Hayward
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Ines I Atmosukarto
- Lipotek Pty Ltd. The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Jason D Price
- Lipotek Pty Ltd. The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Matthew D Johnson
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim, Germany
| | - Avril A B Robertson
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Gaetan Burgio
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - David C Tscharke
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia
| | - Edward M Fox
- Department of Applied Sciences, Northumbria University, Newcastle Upon Tyne, UK
| | - Denisse L Leyton
- Research School of Biology, The Australian National University, Canberra, Australia.,Medical School, The Australian National University, Canberra, Australia
| | - Nadeem O Kaakoush
- School of Medical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim, Germany
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Si Ming Man
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australia.
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12
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McCall RM, Sievers ME, Fattah R, Ghirlando R, Pomerantsev AP, Leppla SH. Bacillus anthracis Virulence Regulator AtxA Binds Specifically to the pagA Promoter Region. J Bacteriol 2019; 201:e00569-19. [PMID: 31570528 PMCID: PMC6832065 DOI: 10.1128/jb.00569-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 01/12/2023] Open
Abstract
Anthrax toxin activator (AtxA) is the master virulence gene regulator of Bacillus anthracis It regulates genes on the chromosome as well as the pXO1 and pXO2 plasmids. It is not clear how AtxA regulates these genes, and direct binding of AtxA to its targets has not been shown. It has been previously suggested that AtxA and other proteins in the Mga/AtxA global transcriptional regulators family bind to the curvature of their DNA targets, although this has never been experimentally proven. Using electrophoretic mobility shift assays, we demonstrate that AtxA binds directly to the promoter region of pagA upstream of the RNA polymerase binding site. We also demonstrate that in vitro, CO2 appears to have no role in AtxA binding. However, phosphomimetic and phosphoablative substitutions in the phosphotransferase system (PTS) regulation domains (PRDs) do appear to influence AtxA binding and pagA regulation. In silico, in vitro, and in vivo analyses demonstrate that one of two hypothesized stem-loops located upstream of the RNA polymerase binding site in the pagA promoter region is important for AtxA binding in vitro and pagA regulation in vivo Our study clarifies the mechanism by which AtxA interacts with one of its targets.IMPORTANCE Anthrax toxin activator (AtxA) regulates the major virulence genes in Bacillus anthracis The bacterium produces the anthrax toxins, and understanding the mechanism of toxin production may facilitate the development of therapeutics for B. anthracis infection. Since the discovery of AtxA 25 years ago, the mechanism by which it regulates its targets has largely remained a mystery. Here, we provide evidence that AtxA binds to the promoter region of the pagA gene encoding the main central protective antigen (PA) component of the anthrax toxin. These data suggest that AtxA binding plays a direct role in gene regulation. Our work also assists in clarifying the role of CO2 in AtxA's gene regulation and provides more evidence for the role of AtxA phosphorylation in virulence gene regulation.
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Affiliation(s)
- Rita M McCall
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Mary E Sievers
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Rasem Fattah
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Andrei P Pomerantsev
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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13
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Abstract
Inflammasomes act as sensors of infection or damage to initiate immune responses.
While extensively studied in rodents, understanding of livestock inflammasomes
is limited. The NLRP1 inflammasome sensor in rodents is activated by
Toxoplasma gondii, Bacillus anthracis
lethal toxin (LT), and potentially other zoonotic pathogens. LT activates NLRP1
by N-terminal proteolysis, inducing macrophage pyroptosis and a pro-inflammatory
cytokine response. In contrast, NLRP1 in macrophages from humans and certain
rodent strains is resistant to LT cleavage, and pyroptosis is not induced.
Evolution of NLRP1 sequences towards those leading to pyroptosis is of interest
in understanding innate immune responses in different hosts. We characterized
NLRP1 in cattle (Bos taurus) and American bison (Bison
bison). Bovine NLRP1 is not cleaved by LT, and cattle and bison
macrophages do not undergo toxin-induced pyroptosis. Additionally, we found a
predicted Nlrp1 splicing isoform in cattle macrophages lacking
the N-terminal domain. Resistance to LT in bovine and human NLRP1 correlates
with evolutionary sequence similarity to rodents. Consistent with LT-resistant
rodents, bovine macrophages undergo a slower non-pyroptotic death in the
presence of LPS and LT. Overall, our findings support the model that NLRP1
activation by LT requires N-terminal cleavage, and provide novel information on
mechanisms underlying immune response diversity.
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Affiliation(s)
- Catherine E Vrentas
- Infectious Bacterial Diseases Unit, National Animal Disease
Center, Agricultural Research Service, US Department of Agriculture, Ames,
USA
- Catherine E Vrentas, Infectious Bacterial
Diseases Unit, National Animal Disease Center, Agricultural Research Service, US
Department of Agriculture, Ames, IA 50010, USA.
| | - Paola M Boggiatto
- Infectious Bacterial Diseases Unit, National Animal Disease
Center, Agricultural Research Service, US Department of Agriculture, Ames,
USA
| | - Steven C Olsen
- Infectious Bacterial Diseases Unit, National Animal Disease
Center, Agricultural Research Service, US Department of Agriculture, Ames,
USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Bethesda, USA
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Bethesda, USA
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14
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Elvina Xavier MA, Liu S, Bugge TH, Torres JB, Mosley M, Hopkins SL, Allen PD, Berridge G, Vendrell I, Fischer R, Kersemans V, Smart S, Leppla SH, Cornelissen B. Tumor Imaging Using Radiolabeled Matrix Metalloproteinase-Activated Anthrax Proteins. J Nucl Med 2019; 60:1474-1482. [PMID: 30954944 PMCID: PMC6785798 DOI: 10.2967/jnumed.119.226423] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 03/13/2019] [Indexed: 11/20/2022] Open
Abstract
Increased activity of matrix metalloproteinases (MMPs) is associated with worse prognosis in different cancer types. The wild-type protective antigen (PA-WT) of the binary anthrax lethal toxin was modified to form a pore in cell membranes only when cleaved by MMPs (to form PA-L1). Anthrax lethal factor (LF) is then able to translocate through these pores. Here, we used a 111In-radiolabeled form of LF with the PA/LF system for noninvasive in vivo imaging of MMP activity in tumor tissue by SPECT. Methods: MMP-mediated activation of PA-L1 was correlated to anthrax receptor expression and MMP activity in a panel of cancer cells (HT1080, MDA-MB-231, B8484, and MCF7). Uptake of 111In-radiolabeled PA-L1, 111In-PA-WTK563C, or 111In-LFE687A (a catalytically inactive LF mutant) in tumor and normal tissues was measured using SPECT/CT imaging in vivo. Results: Activation of PA-L1 in vitro correlated with anthrax receptor expression and MMP activity (HT1080 > MDA-MB-231 > B8484 > MCF7). PA-L1-mediated delivery of 111In-LFE687A was demonstrated and was corroborated using confocal microscopy with fluorescently labeled LFE687A Uptake was blocked by the broad-spectrum MMP inhibitor GM6001. In vivo imaging showed selective accumulation of 111In-PA-L1 in MDA-MB-231 tumor xenografts (5.7 ± 0.9 percentage injected dose [%ID]/g) at 3 h after intravenous administration. 111In-LFE687A was selectively delivered to MMP-positive MDA-MB-231 tumor tissue by MMP-activatable PA-L1 (5.98 ± 0.62 %ID/g) but not by furin-cleavable PA-WT (1.05 ± 0.21 %ID/g) or a noncleavable PA variant control, PA-U7 (2.74 ± 0.24 %ID/g). Conclusion: Taken together, our results indicate that radiolabeled forms of mutated anthrax lethal toxin hold promise for noninvasive imaging of MMP activity in tumor tissue.
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Affiliation(s)
- Mary-Ann Elvina Xavier
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Shihui Liu
- Proteases and Tissue Remodeling Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland; and
| | - Thomas H Bugge
- Proteases and Tissue Remodeling Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland
| | - Julia Baguña Torres
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Michael Mosley
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Samantha L Hopkins
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Phillip D Allen
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Georgina Berridge
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Iolanda Vendrell
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Roman Fischer
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Veerle Kersemans
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Sean Smart
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland; and
| | - Bart Cornelissen
- Department of Oncology, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, United Kingdom
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15
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Xavier MAE, Liu S, Leppla SH, Cornelissen B. Pre-labelling versus direct labelling of anthrax proteins for imaging of matrix metalloproteinases activity using DOTA-GA. Nucl Med Biol 2019; 72-73:49-54. [PMID: 31330412 PMCID: PMC7730038 DOI: 10.1016/j.nucmedbio.2019.07.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/19/2019] [Accepted: 07/17/2019] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Increased activity of matrix metalloproteases (MMPs) is associated with reduced survival in several cancer subtypes. Aiming to produce an MMP tumour cell-selective cytotoxin, we genetically modified both components of the AB-type lethal toxin from Bacillus anthracis. Component A, Protective Antigen (PA-WT), was re-engineered to form an oligomeric pore in cell membranes only when cleaved by MMPs (PA-L1). The pore-translocation domain (LFn - N-terminal, 30 kDa) of the Lethal Factor (LF), component B, was fused to the catalytic domain of Pseudomonas exotoxin-A to increase its cytotoxic effect when delivered to cancerous cells. Here, we develop radiolabelled forms of LFn for MMP activity imaging by SPECT using the LFn/PA-L1 system. METHODS DOTA-GA-maleimide was conjugated to LFn to allow radiolabelling with 111In via two different routes: (1) LFn was conjugated with maleimide-DOTA-GA under mild conditions, and then radiolabelled in acidic conditions at 95°C, or (2) 111In was coordinated to maleimide-DOTA-GA first and then conjugated via maleimide chemistry to LFn. Circular Dichroism Spectroscopy of LFn was performed to evaluate changes in its secondary structure. Cell uptake assays using the differently labelled forms of [111In]In-DOTA-GA-LFn in the presence or not of PA-WT or PA-L1 were performed. RESULTS LFn was successfully radiolabelled by either strategy. Comparison of the secondary structure content of LFn exposed to 37°C or 95°C, showed a loss of alpha helix content at higher temperatures. Cell uptake of both forms of [111In]In-DOTA-GA-LFn, labelled directly or indirectly, was significantly higher in MMP-positive cells, in the presence of PA-L1, compared to controls. Notably, despite being exposed to high temperatures, uptake of directly labelled [111In]In-DOTA-GA-LFndir was higher than indirectly labelled [111In]In-DOTA-GA-LFnindir. CONCLUSIONS 111In-radiolabelling of LFn results in a functional molecule that targets MMP-activity in cells when combined with PA-L1. [111In]In-LFn/PA-L1 is a promising MMP activity imaging agent for SPECT imaging.
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Affiliation(s)
- Mary-Ann Elvina Xavier
- CRUK/MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom
| | - Shihui Liu
- Department of Medicine, Division of Infectious Diseases, University of Pittsburgh, Pittsburgh, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, USA
| | - Bart Cornelissen
- CRUK/MRC Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, United Kingdom.
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16
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Fischer ES, Campbell WA, Liu S, Ghirlando R, Fattah RJ, Bugge TH, Leppla SH. Bismaleimide cross-linked anthrax toxin forms functional octamers with high specificity in tumor targeting. Protein Sci 2019; 28:1059-1070. [PMID: 30942916 DOI: 10.1002/pro.3613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 04/01/2019] [Indexed: 12/12/2022]
Abstract
In recent years, anthrax toxin has been reengineered to act as a highly specific antiangiogenic cancer therapeutic, shown to kill tumors in animal models. This has been achieved by modifying protective antigen (PA) so that its activation and toxicity require the presence of two proteases, matrix metalloproteinase (MMP) and urokinase plasminogen activator (uPA), which are upregulated in tumor microenvironments. These therapeutics consist of intercomplementing PA variants, which are individually nontoxic, but form functional toxins upon complementary oligomerization. Here, we have created a dual-protease requiring PA targeting system which utilizes bismaleimide cross-linked PA (CLPA) rather than the intercomplementing PA variants. Three different CLPA agents were tested and, as expected, found to exclusively form octamers. Two of the CLPA agents have in vitro toxicities equal to those of previous intercomplementing agents, while the third CLPA agent had compromised in vitro cleavage and was significantly less cytotoxic. We hypothesize this difference was due to steric hindrance caused by cross-linking two PA monomers in close proximity to the PA cleavage site. Overall, this work advances the development and use of the PA and LF tumor-targeting system as a practical cancer therapeutic, as it provides a way to reduce the drug components of the anthrax toxin drug delivery system from three to two, which may lower the cost and simplify testing in clinical trials. HIGHLIGHT: Previously, anthrax toxin has been reengineered to act as a highly specific antiangiogenic cancer therapeutic. Here, we present a version, which utilizes bismaleimide cross-linked protective antigen (PA) rather than intercomplementing PA variants. This advances the development of anthrax toxin as a practical cancer therapeutic as it reduces the components of the drug delivery system to two, which may lower the cost and simplify testing in clinical trials.
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Affiliation(s)
- Elyse S Fischer
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
| | - Warren A Campbell
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
| | - Shihui Liu
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, 20892
| | - Rasem J Fattah
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
| | - Thomas H Bugge
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, Bethesda, Maryland
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland
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17
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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18
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Sharma AK, Leppla SH, Pomerantsev AP, Shiloach J. Effect of over expressing protective antigen on global gene transcription in Bacillus anthracis BH500. Sci Rep 2018; 8:16108. [PMID: 30382110 PMCID: PMC6208434 DOI: 10.1038/s41598-018-34196-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 10/08/2018] [Indexed: 01/22/2023] Open
Abstract
Protective antigen (PA) of Bacillus anthracis is being considered as a vaccine candidate against anthrax and its production has been explored in several heterologous host systems. Since the systems tested introduced adverse issues such as inclusion body formation and endotoxin contamination, the production from B. anthracis is considered as a preferred method. The present study examines the effect of PA expression on the metabolism of B. anthracis producing strain, BH500, by comparing it with a control strain carrying an empty plasmid. The strains were grown in a bioreactor and RNA-seq analysis of the producing and non-producing strain was conducted. Among the observed differences, the strain expressing rPA had increased transcription of sigL, the gene encoding RNA polymerase σ54, sigB, the general stress transcription factor gene and its regulators rsbW and rsbV, as well as the global regulatory repressor ctsR. There were also decreased expression of intracellular heat stress related genes such as groL, groES, hslO, dnaJ, and dnaK and increased expression of extracellular chaperons csaA and prsA2. Also, major central metabolism genes belonging to TCA, glycolysis, PPP, and amino acids biosynthesis were up-regulated in the PA-producing strain during the lag phase and down-regulated in the log and late-log phases, which was associated with decreased specific growth rates. The information obtained from this study may guide genetic modification of B. anthracis to improve PA production.
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Affiliation(s)
- Ashish K Sharma
- Biotechnology Core Laboratory, National Institute of Diabetes and Digestives and Kidney Diseases (NIDDK) NIH, Maryland, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, National Institute of Allergy and Infectious diseases (NIAID), NIH, Maryland, USA
| | - Andrei P Pomerantsev
- Microbial Pathogenesis Section, National Institute of Allergy and Infectious diseases (NIAID), NIH, Maryland, USA
| | - Joseph Shiloach
- Biotechnology Core Laboratory, National Institute of Diabetes and Digestives and Kidney Diseases (NIDDK) NIH, Maryland, USA.
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19
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Kalu N, Atsmon-Raz Y, Momben Abolfath S, Lucas L, Kenney C, Leppla SH, Tieleman DP, Nestorovich EM. Effect of late endosomal DOBMP lipid and traditional model lipids of electrophysiology on the anthrax toxin channel activity. Biochim Biophys Acta Biomembr 2018; 1860:2192-2203. [PMID: 30409515 DOI: 10.1016/j.bbamem.2018.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/09/2018] [Accepted: 08/19/2018] [Indexed: 01/26/2023]
Abstract
Anthrax toxin action requires triggering of natural endocytic transport mechanisms whereby the binding component of the toxin forms channels (PA63) within endosomal limiting and intraluminal vesicle membranes to deliver the toxin's enzymatic components into the cytosol. Membrane lipid composition varies at different stages of anthrax toxin internalization, with intraluminal vesicle membranes containing ~70% of anionic bis(monoacylglycero)phosphate lipid. Using model bilayer measurements, we show that membrane lipids can have a strong effect on the anthrax toxin channel properties, including the channel-forming activity, voltage-gating, conductance, selectivity, and enzymatic factor binding. Interestingly, the highest PA63 insertion rate was observed in bis(monoacylglycero)phosphate membranes. The molecular dynamics simulation data show that the conformational properties of the channel are different in bis(monoacylglycero)phosphate compared to PC, PE, and PS lipids. The anthrax toxin protein/lipid bilayer system can be advanced as a novel robust model to directly investigate lipid influence on membrane protein properties and protein/protein interactions.
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Affiliation(s)
- Nnanya Kalu
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA
| | - Yoav Atsmon-Raz
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, 2500 University Drive NW, Calgary T2N 1N4, Alberta, Canada.
| | - Sanaz Momben Abolfath
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA
| | - Laura Lucas
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA
| | - Clare Kenney
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda 20892, MD, USA
| | - D Peter Tieleman
- Department of Biological Sciences, Centre for Molecular Simulation, University of Calgary, 2500 University Drive NW, Calgary T2N 1N4, Alberta, Canada
| | - Ekaterina M Nestorovich
- Department of Biology, The Catholic University of America, 620 Michigan Ave NE, Washington 20064, DC, USA.
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20
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Paliga D, Raudzus F, Leppla SH, Heumann R, Neumann S. Lethal Factor Domain-Mediated Delivery of Nurr1 Transcription Factor Enhances Tyrosine Hydroxylase Activity and Protects from Neurotoxin-Induced Degeneration of Dopaminergic Cells. Mol Neurobiol 2018; 56:3393-3403. [PMID: 30121937 PMCID: PMC6476859 DOI: 10.1007/s12035-018-1311-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 08/08/2018] [Indexed: 12/31/2022]
Abstract
The orphan transcription factor nuclear receptor-related 1 protein (Nurr1, also known as NR4A2) plays a key role in embryonic development and maintenance of mesencephalic dopaminergic neurons in the substantia nigra. Nurr1 deficiency is associated with Parkinson’s disease where dopaminergic neurons degenerate suggesting that counter-regulation of Nurr1 activity may have therapeutic effects. Here, we bacterially expressed and isolated a human Nurr1 fusion protein containing a N-terminal cell delivery domain derived from detoxified anthrax lethal factor followed by wild type ubiquitin with deubiquitinating enzyme recognition site for intracellular cleavage. Addition of the Nurr1 fusion protein to dopaminergic SH-SY5Y cells generated a cleaved, cytosolic Nurr1-containing fragment which was associated with increased levels of tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis. Promoter-activity assays confirmed that exposure of cells to full-length Nurr1 fusion protein activated not only its cognate human tyrosine hydroxylase promoter but also the corresponding mouse sequence, although at a reduced efficiency. Using 6-hydroxydopamine as a dopaminergic cell specific neurotoxin, we demonstrate that full-length Nurr1 fusion protein promotes a concentration-dependent protection from this toxic insult. Altogether, the enhancement of tyrosine hydroxylase in naïve dopaminergic cells and the protective effects in a cellular model of Parkinson’s disease suggest that full-length Nurr1 fusion protein may contribute to the development of a novel concept of protein-based therapy.
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Affiliation(s)
- Dennis Paliga
- Department of Biochemistry II - Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Fabian Raudzus
- Department of Biochemistry II - Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, 44801, Bochum, Germany
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Rolf Heumann
- Department of Biochemistry II - Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, 44801, Bochum, Germany.
| | - Sebastian Neumann
- Department of Biochemistry II - Molecular Neurobiochemistry, Faculty of Chemistry and Biochemistry, Ruhr-Universität Bochum, 44801, Bochum, Germany
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21
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Jiao GS, Kim S, Moayeri M, Thai A, Cregar-Hernandez L, McKasson L, O'Malley S, Leppla SH, Johnson AT. Small molecule inhibitors of anthrax edema factor. Bioorg Med Chem Lett 2017; 28:134-139. [PMID: 29198864 DOI: 10.1016/j.bmcl.2017.11.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 11/23/2017] [Accepted: 11/24/2017] [Indexed: 11/19/2022]
Abstract
Anthrax is a highly lethal disease caused by the Gram-(+) bacteria Bacillus anthracis. Edema toxin (ET) is a major contributor to the pathogenesis of disease in humans exposed to B. anthracis. ET is a bipartite toxin composed of two proteins secreted by the vegetative bacteria, edema factor (EF) and protective antigen (PA). Our work towards identifying a small molecule inhibitor of anthrax edema factor is the subject of this letter. First we demonstrate that the small molecule probe 5'-Fluorosulfonylbenzoyl 5'-adenosine (FSBA) reacts irreversibly with EF and blocks enzymatic activity. We then show that the adenosine portion of FSBA can be replaced to provide more drug-like molecules which are up to 1000-fold more potent against EF relative to FSBA, display low cross reactivity when tested against a panel of kinases, and are nanomolar inhibitors of EF in a cell-based assay of cAMP production.
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Affiliation(s)
- Guan-Sheng Jiao
- Hawaii Biotech, 650 Iwilei Road, Suite 204, Honolulu, HI 96817, USA
| | - Seongjin Kim
- Hawaii Biotech, 650 Iwilei Road, Suite 204, Honolulu, HI 96817, USA
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - April Thai
- Hawaii Biotech, 650 Iwilei Road, Suite 204, Honolulu, HI 96817, USA
| | | | - Linda McKasson
- Hawaii Biotech, 650 Iwilei Road, Suite 204, Honolulu, HI 96817, USA
| | - Sean O'Malley
- Hawaii Biotech, 650 Iwilei Road, Suite 204, Honolulu, HI 96817, USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alan T Johnson
- Hawaii Biotech, 650 Iwilei Road, Suite 204, Honolulu, HI 96817, USA.
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22
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Guichard A, Jain P, Moayeri M, Schwartz R, Chin S, Zhu L, Cruz-Moreno B, Liu JZ, Aguilar B, Hollands A, Leppla SH, Nizet V, Bier E. Anthrax edema toxin disrupts distinct steps in Rab11-dependent junctional transport. PLoS Pathog 2017; 13:e1006603. [PMID: 28945820 PMCID: PMC5612732 DOI: 10.1371/journal.ppat.1006603] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 08/24/2017] [Indexed: 02/06/2023] Open
Abstract
Various bacterial toxins circumvent host defenses through overproduction of cAMP. In a previous study, we showed that edema factor (EF), an adenylate cyclase from Bacillus anthracis, disrupts endocytic recycling mediated by the small GTPase Rab11. As a result, cargo proteins such as cadherins fail to reach inter-cellular junctions. In the present study, we provide further mechanistic dissection of Rab11 inhibition by EF using a combination of Drosophila and mammalian systems. EF blocks Rab11 trafficking after the GTP-loading step, preventing a constitutively active form of Rab11 from delivering cargo vesicles to the plasma membrane. Both of the primary cAMP effector pathways -PKA and Epac/Rap1- contribute to inhibition of Rab11-mediated trafficking, but act at distinct steps of the delivery process. PKA acts early, preventing Rab11 from associating with its effectors Rip11 and Sec15. In contrast, Epac functions subsequently via the small GTPase Rap1 to block fusion of recycling endosomes with the plasma membrane, and appears to be the primary effector of EF toxicity in this process. Similarly, experiments conducted in mammalian systems reveal that Epac, but not PKA, mediates the activity of EF both in cell culture and in vivo. The small GTPase Arf6, which initiates endocytic retrieval of cell adhesion components, also contributes to junctional homeostasis by counteracting Rab11-dependent delivery of cargo proteins at sites of cell-cell contact. These studies have potentially significant practical implications, since chemical inhibition of either Arf6 or Epac blocks the effect of EF in cell culture and in vivo, opening new potential therapeutic avenues for treating symptoms caused by cAMP-inducing toxins or related barrier-disrupting pathologies. Recent anthrax outbreaks in Zambia and northern Russia and biodefense preparedness highlight the need for new therapies to counteract fatal late-stage pathologies in patients infected with Bacillus anthracis. Indeed, two toxins secreted by this pathogen—edema toxin (ET) and lethal toxin (LT)—can cause death in face of effective antibiotic treatment. ET, a potent adenylate cyclase, severely impacts host cells and tissues through an overproduction of the ubiquitous second messenger cAMP. Previously, we identified Rab11 as a key host factor inhibited by ET. Blockade of Rab11-dependent endocytic recycling resulted in the disruption of intercellular junctions, likely contributing to life threatening vascular effusion observed in anthrax patients. Here we present a multi-system analysis of the mechanism by which EF inhibits Rab11 and exocyst-dependent trafficking. Epistasis experiments in Drosophila reveal that over-activation of the cAMP effectors PKA and Epac/Rap1 interferes with Rab11-mediated trafficking at two distinct steps. We further describe conserved roles of Epac and the small GTPase Arf6 in ET-mediated disruption of vesicular trafficking and show how chemical inhibition of either pathway greatly alleviates ET-induced edema. Thus, our study defines Epac and Arf6 as promising drug targets for the treatment of infectious diseases and other pathologies involving cAMP overload or related barrier disruption.
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Affiliation(s)
- Annabel Guichard
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America
| | - Prashant Jain
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, United States of America
| | - Ruth Schwartz
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America
| | - Stephen Chin
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America
| | - Lin Zhu
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America
| | - Beatriz Cruz-Moreno
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America
| | - Janet Z. Liu
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States of America
| | - Bernice Aguilar
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States of America
- Division of Pediatric Infectious Diseases and the Immunobiology Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA 90048, United States of America
| | - Andrew Hollands
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States of America
| | - Stephen H. Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD, United States of America
| | - Victor Nizet
- Department of Pediatrics, University of California, San Diego, La Jolla, CA, United States of America
- Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States of America
| | - Ethan Bier
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, United States of America
- * E-mail:
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23
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Tao P, Mahalingam M, Zhu J, Moayeri M, Kirtley ML, Fitts EC, Andersson JA, Lawrence WS, Leppla SH, Chopra AK, Rao VB. A Bivalent Anthrax-Plague Vaccine That Can Protect against Two Tier-1 Bioterror Pathogens, Bacillus anthracis and Yersinia pestis. Front Immunol 2017; 8:687. [PMID: 28694806 PMCID: PMC5483451 DOI: 10.3389/fimmu.2017.00687] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 05/26/2017] [Indexed: 01/14/2023] Open
Abstract
Bioterrorism remains as one of the biggest challenges to global security and public health. Since the deadly anthrax attacks of 2001 in the United States, Bacillus anthracis and Yersinia pestis, the causative agents of anthrax and plague, respectively, gained notoriety and were listed by the CDC as Tier-1 biothreat agents. Currently, there is no Food and Drug Administration-approved vaccine against either of these threats for mass vaccination to protect general public, let alone a bivalent vaccine. Here, we report the development of a single recombinant vaccine, a triple antigen consisting of all three target antigens, F1 and V from Y. pestis and PA from B. anthracis, in a structurally stable context. Properly folded and soluble, the triple antigen retained the functional and immunogenicity properties of all three antigens. Remarkably, two doses of this immunogen adjuvanted with Alhydrogel® elicited robust antibody responses in mice, rats, and rabbits and conferred complete protection against inhalational anthrax and pneumonic plague. No significant antigenic interference was observed. Furthermore, we report, for the first time, complete protection of animals against simultaneous challenge with Y. pestis and the lethal toxin of B. anthracis, demonstrating that a single biodefense vaccine can protect against a bioterror attack with weaponized B. anthracis and/or Y. pestis. This bivalent anthrax–plague vaccine is, therefore, a strong candidate for stockpiling, after demonstration of its safety and immunogenicity in human clinical trials, as part of national preparedness against two of the deadliest bioterror threats.
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Affiliation(s)
- Pan Tao
- Department of Biology, The Catholic University of America, Washington, DC, United States
| | - Marthandan Mahalingam
- Department of Biology, The Catholic University of America, Washington, DC, United States
| | - Jingen Zhu
- Department of Biology, The Catholic University of America, Washington, DC, United States
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Michelle L Kirtley
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Eric C Fitts
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jourdan A Andersson
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - William S Lawrence
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States.,Galveston National Laboratory, University of Texas Medical Branch, Galveston, TX, United States
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Ashok K Chopra
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States.,Galveston National Laboratory, University of Texas Medical Branch, Galveston, TX, United States.,Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States.,Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX, United States.,Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
| | - Venigalla B Rao
- Department of Biology, The Catholic University of America, Washington, DC, United States
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24
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Liu S, Ma Q, Fattah R, Bugge TH, Leppla SH. Anti-tumor activity of anthrax toxin variants that form a functional translocation pore by intermolecular complementation. Oncotarget 2017; 8:65123-65131. [PMID: 29029417 PMCID: PMC5630317 DOI: 10.18632/oncotarget.17729] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/16/2017] [Indexed: 12/31/2022] Open
Abstract
Anthrax lethal toxin is a typical A-B type protein toxin secreted by Bacillus anthracis. Lethal factor (LF) is the catalytic A-subunit, a metalloprotease having MEKs as targets. LF relies on the cell-binding B-subunit, protective antigen (PA), to gain entry into the cytosol of target cells. PA binds to cell surface toxin receptors and is activated by furin protease to form an LF-binding-competent oligomer-PA pre-pore, which converts to a functional protein-conductive pore in the acidic endocytic vesicles, allowing translocation of LF into the cytosol. During PA pre-pore-to-pore conversion, the intermolecular salt bridge interactions between Lys397 and Asp426 on adjacent PA protomers play a critical role in positioning neighboring luminal Phe427 residues to form the Phe-clamp, an essential element of the PA functional pore. This essential intermolecular interaction affords the opportunity to create pairs of PA variants that depend on intermolecular complementation to form a functional pore. We have previously generated PA variants with furin-cleavage site replaced by substrate sequences of tumor-associated proteases, such as urokinase or MMPs. Here we show that PA-U2-K397Q, a urokinase-activated PA variant with Lys397 residue replaced by glutamine, and PA-L1-D426K, a MMP-activated PA variant with Asp426 changed to lysine, do not form functional pores both in vitro or in vivo unless they are used together. Further, the mixture of PA-U2-K397Q and PA-L1-D426K displayed potent anti-tumor activity in the presence of LF. Thus, PA-U2-K397Q and PA-L1-D426K form a novel intermolecular complementation system with toxin activation relying on the presence of two distinct tumor-associated proteases, i.e., urokinase and MMPs.
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Affiliation(s)
- Shihui Liu
- Proteases and Tissue Remodeling Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.,Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Qian Ma
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rasem Fattah
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Thomas H Bugge
- Proteases and Tissue Remodeling Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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25
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Arolas JL, Goulas T, Pomerantsev AP, Leppla SH, Gomis-Rüth FX. Structural Basis for Latency and Function of Immune Inhibitor A Metallopeptidase, a Modulator of the Bacillus anthracis Secretome. Structure 2016; 24:25-36. [PMID: 26745529 DOI: 10.1016/j.str.2015.10.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Revised: 10/15/2015] [Accepted: 10/15/2015] [Indexed: 01/07/2023]
Abstract
Immune inhibitor A(InhA)-type metallopeptidases are potential virulence factors secreted by members of the Bacillus cereus group. Two paralogs from anthrax-causing Bacillus anthracis (BaInhA1 and BaInhA2) were shown to degrade host tissue proteins with broad substrate specificity. Analysis of their activation mechanism and the crystal structure of a zymogenic BaInhA2 variant revealed a ∼750-residue four-domain structure featuring a pro-peptide, a catalytic domain, a domain reminiscent of viral envelope glycoproteins, and a MAM domain grafted into the latter. This domain, previously found only in eukaryotes, is required for proper protein expression in B. anthracis and evinces certain flexibility. Latency is uniquely modulated by the N-terminal segment of the pro-peptide, which binds the catalytic zinc through its α-amino group and occupies the primed side of the active-site cleft. The present results further our understanding of the modus operandi of an anthrax secretome regulator.
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Affiliation(s)
- Joan L Arolas
- Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac, 15-21, 08028 Barcelona, Spain
| | - Theodoros Goulas
- Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac, 15-21, 08028 Barcelona, Spain
| | - Andrei P Pomerantsev
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - F Xavier Gomis-Rüth
- Proteolysis Lab, Department of Structural Biology ("María de Maeztu" Unit of Excellence), Molecular Biology Institute of Barcelona, Spanish Research Council (CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac, 15-21, 08028 Barcelona, Spain.
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26
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Martin EW, Buzza MS, Driesbaugh KH, Liu S, Fortenberry YM, Leppla SH, Antalis TM. Targeting the membrane-anchored serine protease testisin with a novel engineered anthrax toxin prodrug to kill tumor cells and reduce tumor burden. Oncotarget 2016; 6:33534-53. [PMID: 26392335 PMCID: PMC4741784 DOI: 10.18632/oncotarget.5214] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 09/03/2015] [Indexed: 02/04/2023] Open
Abstract
The membrane-anchored serine proteases are a unique group of trypsin-like serine proteases that are tethered to the cell surface via transmembrane domains or glycosyl-phosphatidylinositol-anchors. Overexpressed in tumors, with pro-tumorigenic properties, they are attractive targets for protease-activated prodrug-like anti-tumor therapies. Here, we sought to engineer anthrax toxin protective antigen (PrAg), which is proteolytically activated on the cell surface by the proprotein convertase furin to instead be activated by tumor cell-expressed membrane-anchored serine proteases to function as a tumoricidal agent. PrAg's native activation sequence was mutated to a sequence derived from protein C inhibitor (PCI) that can be cleaved by membrane-anchored serine proteases, to generate the mutant protein PrAg-PCIS. PrAg-PCIS was resistant to furin cleavage in vitro, yet cytotoxic to multiple human tumor cell lines when combined with FP59, a chimeric anthrax toxin lethal factor-Pseudomonas exotoxin fusion protein. Molecular analyses showed that PrAg-PCIS can be cleaved in vitro by several serine proteases including the membrane-anchored serine protease testisin, and mediates increased killing of testisin-expressing tumor cells. Treatment with PrAg-PCIS also potently attenuated the growth of testisin-expressing xenograft tumors in mice. The data indicates PrAg can be engineered to target tumor cell-expressed membrane-anchored serine proteases to function as a potent tumoricidal agent.
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Affiliation(s)
- Erik W Martin
- Center for Vascular and Inflammatory Diseases and the Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Marguerite S Buzza
- Center for Vascular and Inflammatory Diseases and the Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Kathryn H Driesbaugh
- Center for Vascular and Inflammatory Diseases and the Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Shihui Liu
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yolanda M Fortenberry
- Division of Pediatric Hematology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Stephen H Leppla
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Toni M Antalis
- Center for Vascular and Inflammatory Diseases and the Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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27
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Chen KH, Liu S, Leysath CE, Miller-Randolph S, Zhang Y, Fattah R, Bugge TH, Leppla SH. Anthrax Toxin Protective Antigen Variants That Selectively Utilize either the CMG2 or TEM8 Receptors for Cellular Uptake and Tumor Targeting. J Biol Chem 2016; 291:22021-22029. [PMID: 27555325 DOI: 10.1074/jbc.m116.753301] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Indexed: 11/06/2022] Open
Abstract
The protective antigen (PA) moiety of anthrax toxin binds to cellular receptors and mediates the translocation of the two enzymatic moieties of the toxin to the cytosol. Two PA receptors are known, with capillary morphogenesis protein 2 (CMG2) being the more important for pathogenesis and tumor endothelial marker 8 (TEM8) playing a minor role. The C-terminal PA domain 4 (PAD4) has extensive interactions with the receptors and is required for binding. Our previous study identified PAD4 variants having enhanced TEM8 binding specificity. To obtain PA variants that selectively bind to CMG2, here we performed phage display selections using magnetic beads having bound CMG2. We found that PA residue isoleucine 656 plays a critical role in PA binding to TEM8 but has a much lesser effect on PA binding to CMG2. We further characterized the role of residue 656 in distinguishing PA binding to CMG2 versus TEM8 by substituting it with the other 19 amino acids. Of the resulting variants, PA I656Q and PA I656V had significantly reduced activity on TEM8-expressing CHO cells but maintained their activity on CMG2-expressing CHO cells. The preference of these PA mutants for CMG2 over TEM8 was further demonstrated using mouse embryonic fibroblast cells and mice deficient in the CMG2 and/or the TEM8 receptors. The structural basis of the alterations in the receptor binding activities of these mutants is also discussed.
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Affiliation(s)
- Kuang-Hua Chen
- From the Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892-3202 and
| | - Shihui Liu
- From the Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892-3202 and the Proteases and Tissue Remodeling Section, Oral and Pharyngeal Cancer Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - Clinton E Leysath
- From the Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892-3202 and
| | - Sharmina Miller-Randolph
- From the Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892-3202 and
| | - Yi Zhang
- From the Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892-3202 and
| | - Rasem Fattah
- From the Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892-3202 and
| | - Thomas H Bugge
- the Proteases and Tissue Remodeling Section, Oral and Pharyngeal Cancer Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892
| | - Stephen H Leppla
- From the Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892-3202 and
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28
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Vrentas CE, Moayeri M, Keefer AB, Greaney AJ, Tremblay J, O'Mard D, Leppla SH, Shoemaker CB. A Diverse Set of Single-domain Antibodies (VHHs) against the Anthrax Toxin Lethal and Edema Factors Provides a Basis for Construction of a Bispecific Agent That Protects against Anthrax Infection. J Biol Chem 2016; 291:21596-21606. [PMID: 27539858 DOI: 10.1074/jbc.m116.749184] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/08/2016] [Indexed: 01/08/2023] Open
Abstract
Infection with Bacillus anthracis, the causative agent of anthrax, can lead to persistence of lethal secreted toxins in the bloodstream, even after antibiotic treatment. VHH single-domain antibodies have been demonstrated to neutralize diverse bacterial toxins both in vitro and in vivo, with protein properties such as small size and high stability that make them attractive therapeutic candidates. Recently, we reported on VHHs with in vivo activity against the protective antigen component of the anthrax toxins. Here, we characterized a new set of 15 VHHs against the anthrax toxins that act by binding to the edema factor (EF) and/or lethal factor (LF) components. Six of these VHHs are cross-reactive against both EF and LF and recognize the N-terminal domain (LFN, EFN) of their target(s) with subnanomolar affinity. The cross-reactive VHHs block binding of EF/LF to the protective antigen C-terminal binding interface, preventing toxin entry into the cell. Another VHH appears to recognize the LF C-terminal domain and exhibits a kinetic effect on substrate cleavage by LF. A subset of the VHHs neutralized against EF and/or LF in murine macrophage assays, and the neutralizing VHHs that were tested improved survival of mice in a spore model of anthrax infection. Finally, a bispecific VNA (VHH-based neutralizing agent) consisting of two linked toxin-neutralizing VHHs, JMN-D10 and JMO-G1, was fully protective against lethal anthrax spore infection in mice as a single dose. This set of VHHs should facilitate development of new therapeutic VNAs and/or diagnostic agents for anthrax.
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Affiliation(s)
- Catherine E Vrentas
- From the Department of Biology, Frostburg State University, Frostburg, Maryland 50010.,Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Andrea B Keefer
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Allison J Greaney
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Jacqueline Tremblay
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Maryland 01536
| | - Danielle O'Mard
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892, and
| | - Charles B Shoemaker
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Maryland 01536
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29
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Abstract
Anthrax toxin is a potent tripartite protein toxin from Bacillus anthracis. It is one of the two virulence factors and causes the disease anthrax. The receptor-binding component of the toxin, protective antigen, needs to be cleaved by furin-like proteases to be activated and to deliver the enzymatic moieties lethal factor and edema factor to the cytosol of cells. Alteration of the protease cleavage site allows the activation of the toxin selectively in response to the presence of tumor-associated proteases. This initial idea of re-targeting anthrax toxin to tumor cells was further elaborated in recent years and resulted in the design of many modifications of anthrax toxin, which resulted in successful tumor therapy in animal models. These modifications include the combination of different toxin variants that require activation by two different tumor-associated proteases for increased specificity of toxin activation. The anthrax toxin system has proved to be a versatile system for drug delivery of several enzymatic moieties into cells. This highly efficient delivery system has recently been further modified by introducing ubiquitin as a cytosolic cleavage site into lethal factor fusion proteins. This review article describes the latest developments in this field of tumor targeting and drug delivery.
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Affiliation(s)
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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30
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Al-Dimassi S, Salloum G, Saykali B, Khoury O, Liu S, Leppla SH, Abi-Habib R, El-Sibai M. Targeting the MAP kinase pathway in astrocytoma cells using a recombinant anthrax lethal toxin as a way to inhibit cell motility and invasion. Int J Oncol 2016; 48:1913-20. [PMID: 26984023 DOI: 10.3892/ijo.2016.3431] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 11/05/2015] [Indexed: 01/30/2023] Open
Abstract
Malignant astrocytomas are highly invasive into adjacent and distant regions of the normal brain. Understanding and targeting cancer cell invasion is an important therapeutic approach. Cell invasion is a complex process that replies on many signaling pathways including the mitogen-activated protein (MAP) kinase (MAPK). In many cell lines, the use of MAPK-targeted drugs proved to be a potential method to inhibit cancer cell motility. In the present study, we use a recombinant anthrax lethal toxin (LeTx), which selectively inhibits the MAPK pathway, in order to target invasion. LeTx proved ineffective on cell survival in astrocytoma (as well as normal cells). However, astrocytoma cells that were treated with LeTx showed a significant decrease in cell motility as seen by wound healing as well as random 2D motility in serum. The cells also showed a decrease in invasion across a collagen matrix. The effect of LeTx on cell migration was mediated though the deregulation of Rho GTPases, which play a role in cell motility. Finally, the effect of LeTx on cell migration and Rho GTPases was mimicked by the inhibition of the MAPK pathway. In this study, we describe for the first time the effect of the LeTx on cancer cell motility and invasion not cell survival making it a potentially selective brain tumor invasion inhibitor.
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Affiliation(s)
- Saleh Al-Dimassi
- Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon
| | - Gilbert Salloum
- Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon
| | - Bechara Saykali
- Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon
| | - Oula Khoury
- Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon
| | - Shihui Liu
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ralph Abi-Habib
- Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon
| | - Mirvat El-Sibai
- Department of Natural Sciences, The Lebanese American University, Beirut 1102 2801, Lebanon
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31
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Abstract
The inflammasomes are intracellular protein complexes that play an important role in innate immune sensing. Activation of inflammasomes leads to activation of caspase-1 and maturation and secretion of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18. In certain myeloid cells, this activation can also lead to an inflammatory cell death (pyroptosis). Inflammasome sensor proteins have evolved to detect a range of microbial ligands and bacterial exotoxins either through direct interaction or by detection of host cell changes elicited by these effectors. Bacterial exotoxins activate the inflammasomes through diverse processes, including direct sensor cleavage, modulation of ion fluxes through plasma membrane pore formation, and perturbation of various host cell functions. In this review, we summarize the findings on some of the bacterial exotoxins that activate the inflammasomes.
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Affiliation(s)
- Allison J Greaney
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, MD , USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, MD , USA
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, MD , USA
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32
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Bekdash A, Darwish M, Timsah Z, Kassab E, Ghanem H, Najjar V, Ghosn M, Nasser S, El-Hajj H, Bazerbachi A, Liu S, Leppla SH, Frankel AE, Abi-Habib RJ. Phospho-MEK1/2 and uPAR Expression Determine Sensitivity of AML Blasts to a Urokinase-Activated Anthrax Lethal Toxin (PrAgU2/LF). Transl Oncol 2015; 8:347-357. [PMID: 26500025 PMCID: PMC4630967 DOI: 10.1016/j.tranon.2015.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 07/09/2015] [Accepted: 07/14/2015] [Indexed: 02/04/2023] Open
Abstract
In this study, we attempt to target both the urokinase plasminogen activator and the mitogen-activated protein kinase pathway in acute myeloid leukemia (AML) cell lines and primary AML blasts using PrAgU2/LF, a urokinase-activated anthrax lethal toxin. PrAgU2/LF was cytotoxic to five out of nine AML cell lines. Cytotoxicity of PrAgU2/LF appeared to be nonapoptotic and was associated with MAPK activation and urokinase activity because all the PrAgU2/LF-sensitive cell lines showed both uPAR expression and high levels of MEK1/2 phosphorylation. Inhibition of uPAR or desensitization of cells to MEK1/2 inhibition blocked toxicity of PrAgU2/LF, indicating requirement for both uPAR expression and MAPK activation for activity. PrAgU2/LF was also cytotoxic to primary blasts from AML patients, with blasts from four out of five patients showing a cytotoxic response to PrAgU2/LF. Cytotoxicity of primary AML blasts was also dependent on uPAR expression and phos-MEK1/2 levels. CD34(+) bone marrow blasts and peripheral blood mononuclear cells lacked uPAR expression and were resistant to PrAgU2/LF, demonstrating the lack of toxicity to normal hematological cells and, therefore, the tumor selectivity of this approach. Dose escalation in mice revealed that the maximal tolerated dose of PrAgU2/LF is at least 5.7-fold higher than that of the wild-type anthrax lethal toxin, PrAg/LF, further demonstrating the increased safety of this molecule. We have shown, in this study, that PrAgU2/LF is a novel, dual-specific molecule for the selective targeting of AML.
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Affiliation(s)
- Amira Bekdash
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Beirut 1102 2801, Lebanon
| | - Manal Darwish
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Beirut 1102 2801, Lebanon
| | - Zahra Timsah
- School of Molecular & Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK
| | - Elias Kassab
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Beirut 1102 2801, Lebanon
| | - Hadi Ghanem
- Department of Internal Medicine, School of Medicine, Lebanese American University, Beirut 1102-2801, Lebanon
| | - Vicky Najjar
- Department of Pathology, School of Medicine, Lebanese American University, Beirut 1102-2801, Lebanon
| | - Marwan Ghosn
- Department of Pathology, School of Medicine, Lebanese American University, Beirut 1102-2801, Lebanon
| | - Selim Nasser
- Department of Pathology, School of Medicine, Lebanese American University, Beirut 1102-2801, Lebanon
| | - Hiba El-Hajj
- Department of Internal Medicine and Experimental Pathology, School of Medicine, American University of Beirut, Lebanon; Department of Immunology and Microbiology, School of Medicine, American University of Beirut, Lebanon
| | - Ali Bazerbachi
- Department of Internal Medicine, School of Medicine, American University of Beirut, Lebanon; Department of Anatomy, School of Medicine, American University of Beirut, Lebanon; Department of Cell Biology and Physiological Sciences, School of Medicine, American University of Beirut, Lebanon
| | - Shihui Liu
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Arthur E Frankel
- Simmons Comprehensive Cancer Center, UT Southwestern Medical Center, Dallas, Texas 75390
| | - Ralph J Abi-Habib
- Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Beirut 1102 2801, Lebanon.
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33
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Vrentas C, Ghirlando R, Keefer A, Hu Z, Tomczak A, Gittis AG, Murthi A, Garboczi DN, Gottesman S, Leppla SH. Hfqs in Bacillus anthracis: Role of protein sequence variation in the structure and function of proteins in the Hfq family. Protein Sci 2015; 24:1808-19. [PMID: 26271475 DOI: 10.1002/pro.2773] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 08/13/2015] [Indexed: 11/10/2022]
Abstract
Hfq proteins in Gram-negative bacteria play important roles in bacterial physiology and virulence, mediated by binding of the Hfq hexamer to small RNAs and/or mRNAs to post-transcriptionally regulate gene expression. However, the physiological role of Hfqs in Gram-positive bacteria is less clear. Bacillus anthracis, the causative agent of anthrax, uniquely expresses three distinct Hfq proteins, two from the chromosome (Hfq1, Hfq2) and one from its pXO1 virulence plasmid (Hfq3). The protein sequences of Hfq1 and 3 are evolutionarily distinct from those of Hfq2 and of Hfqs found in other Bacilli. Here, the quaternary structure of each B. anthracis Hfq protein, as produced heterologously in Escherichia coli, was characterized. While Hfq2 adopts the expected hexamer structure, Hfq1 does not form similarly stable hexamers in vitro. The impact on the monomer-hexamer equilibrium of varying Hfq C-terminal tail length and other sequence differences among the Hfqs was examined, and a sequence region of the Hfq proteins that was involved in hexamer formation was identified. It was found that, in addition to the distinct higher-order structures of the Hfq homologs, they give rise to different phenotypes. Hfq1 has a disruptive effect on the function of E. coli Hfq in vivo, while Hfq3 expression at high levels is toxic to E. coli but also partially complements Hfq function in E. coli. These results set the stage for future studies of the roles of these proteins in B. anthracis physiology and for the identification of sequence determinants of phenotypic complementation.
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Affiliation(s)
- Catherine Vrentas
- NIAID, National Institutes of Health (NIH), 33 North Drive, Bethesda, Maryland
| | | | - Andrea Keefer
- NIAID, National Institutes of Health (NIH), 33 North Drive, Bethesda, Maryland
| | - Zonglin Hu
- NIAID, National Institutes of Health (NIH), 33 North Drive, Bethesda, Maryland
| | | | - Apostolos G Gittis
- Structural Biology Section, Research Technologies Branch, NIAID, NIH, Twinbrook II, 12441 Parklawn Drive, Rockville, Maryland
| | - Athulaprabha Murthi
- NIAID, National Institutes of Health (NIH), 33 North Drive, Bethesda, Maryland
| | - David N Garboczi
- Structural Biology Section, Research Technologies Branch, NIAID, NIH, Twinbrook II, 12441 Parklawn Drive, Rockville, Maryland
| | | | - Stephen H Leppla
- NIAID, National Institutes of Health (NIH), 33 North Drive, Bethesda, Maryland
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34
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Greaney AJ, Maier NK, Leppla SH, Moayeri M. Sulforaphane inhibits multiple inflammasomes through an Nrf2-independent mechanism. J Leukoc Biol 2015; 99:189-99. [PMID: 26269198 DOI: 10.1189/jlb.3a0415-155rr] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 07/28/2015] [Indexed: 12/18/2022] Open
Abstract
The inflammasomes are intracellular complexes that have an important role in cytosolic innate immune sensing and pathogen defense. Inflammasome sensors detect a diversity of intracellular microbial ligands and endogenous danger signals and activate caspase-1, thus initiating maturation and release of the proinflammatory cytokines interleukin-1β and interleukin-18. These events, although crucial to the innate immune response, have also been linked to the pathology of several inflammatory and autoimmune disorders. The natural isothiocyanate sulforaphane, present in broccoli sprouts and available as a dietary supplement, has gained attention for its antioxidant, anti-inflammatory, and chemopreventive properties. We discovered that sulforaphane inhibits caspase-1 autoproteolytic activation and interleukin-1β maturation and secretion downstream of the nucleotide-binding oligomerization domain-like receptor leucine-rich repeat proteins NLRP1 and NLRP3, NLR family apoptosis inhibitory protein 5/NLR family caspase-1 recruitment domain-containing protein 4 (NAIP5/NLRC4), and absent in melanoma 2 (AIM2) inflammasome receptors. Sulforaphane does not inhibit the inflammasome by direct modification of active caspase-1 and its mechanism is not dependent on protein degradation by the proteasome or de novo protein synthesis. Furthermore, sulforaphane-mediated inhibition of the inflammasomes is independent of the transcription factor nuclear factor erythroid-derived 2-like factor 2 (Nrf2) and the antioxidant response-element pathway, to which many of the antioxidant and anti-inflammatory effects of sulforaphane have been attributed. Sulforaphane was also found to inhibit cell recruitment to the peritoneum and interleukin-1β secretion in an in vivo peritonitis model of acute gout and to reverse NLRP1-mediated murine resistance to Bacillus anthracis spore infection. These findings demonstrate that sulforaphane inhibits the inflammasomes through a novel mechanism and contributes to our understanding of the beneficial effects of sulforaphane.
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Affiliation(s)
- Allison J Greaney
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA
| | - Nolan K Maier
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA
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35
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Abstract
Anthrax is caused by the spore-forming, gram-positive bacterium Bacillus anthracis. The bacterium's major virulence factors are (a) the anthrax toxins and (b) an antiphagocytic polyglutamic capsule. These are encoded by two large plasmids, the former by pXO1 and the latter by pXO2. The expression of both is controlled by the bicarbonate-responsive transcriptional regulator, AtxA. The anthrax toxins are three polypeptides-protective antigen (PA), lethal factor (LF), and edema factor (EF)-that come together in binary combinations to form lethal toxin and edema toxin. PA binds to cellular receptors to translocate LF (a protease) and EF (an adenylate cyclase) into cells. The toxins alter cell signaling pathways in the host to interfere with innate immune responses in early stages of infection and to induce vascular collapse at late stages. This review focuses on the role of anthrax toxins in pathogenesis. Other virulence determinants, as well as vaccines and therapeutics, are briefly discussed.
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Affiliation(s)
- Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
| | - Catherine Vrentas
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
| | - Andrei P Pomerantsev
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
| | - Shihui Liu
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892; , , , ,
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36
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Remy KE, Cui X, Li Y, Sun J, Solomon SB, Fitz Y, Barochia AV, Al-Hamad M, Moayeri M, Leppla SH, Eichacker PQ. Raxibacumab augments hemodynamic support and improves outcomes during shock with B. anthracis edema toxin alone or together with lethal toxin in canines. Intensive Care Med Exp 2015; 3:9. [PMID: 26097803 PMCID: PMC4473792 DOI: 10.1186/s40635-015-0043-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/04/2015] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Lethal and edema toxin contribute to shock and lethality with Bacillus anthracis. We showed previously in a 96-h sedated canine model that raxibacumab, a monoclonal antibody against protective antigen, augmented hemodynamic support (HS) and improved survival with lethal toxin challenge. Here we study raxibacumab further. Using this model, we have now studied raxibacumab with 24 h edema toxin challenges (Study 1), and lethal and edema toxin challenges together (Study 2). METHODS Using our canine model, we have now studied raxibacumab with 24h edema toxin challenges (Study-1), and lethal and edema toxin challenges together (Study-2). RESULTS In Study 1, compared to no treatment, HS (titrated fluid and norepinephrine) increased mean arterial blood pressure (MAP, p ≤ 0.05) but not survival [0 of 10 (0/10) animals survived in each group] or median survival time [43.8 h (range 16.8 to 80.3) vs. 45.2 h (21.0 to 57.1)]. Compared to HS, HS with raxibacumab treatment at or 6 h after the beginning of edema toxin increased MAP and survival rate (6/7 and 7/8, respectively) and time [96.0 h (39.5 to 96.0) and 96.0 h (89.5 to 96.0), respectively]; (p ≤ 0.05). HS with raxibacumab at 12 h increased MAP (p ≤ 0.05) but not survival [1/5; 55.3 h (12.6 to 96.0)]. In Study-2, survival rate and time increased with HS and raxibacumab at 0 h (4/4) or 6 h after (3/3) beginning lethal and edema toxin compared to HS [0/5; 71.5 h (65 to 93)] (p = 0.01 averaged over raxibacumab groups). CONCLUSIONS Raxibacumab augments HS and improves survival during shock with lethal and edema toxin.
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Affiliation(s)
- Kenneth E Remy
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bldg 10, Rm 2C145, Bethesda, MD, 20892, USA.
| | - Xizhong Cui
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bldg 10, Rm 2C145, Bethesda, MD, 20892, USA.
| | - Yan Li
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bldg 10, Rm 2C145, Bethesda, MD, 20892, USA.
| | - Junfeng Sun
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bldg 10, Rm 2C145, Bethesda, MD, 20892, USA.
| | - Steven B Solomon
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bldg 10, Rm 2C145, Bethesda, MD, 20892, USA.
| | - Yvonne Fitz
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bldg 10, Rm 2C145, Bethesda, MD, 20892, USA.
| | - Amisha V Barochia
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Mariam Al-Hamad
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bldg 10, Rm 2C145, Bethesda, MD, 20892, USA.
| | - Mahtab Moayeri
- National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, USA.
| | - Stephen H Leppla
- National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, USA.
| | - Peter Q Eichacker
- Critical Care Medicine Department, Clinical Center, National Institutes of Health, Bldg 10, Rm 2C145, Bethesda, MD, 20892, USA.
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Abstract
Inflammasomes are cytosolic protein complexes that respond to diverse danger signals by activating caspase-1. The sensor components of the inflammasome, often proteins of the nucleotide-binding oligomerization domain-like receptor (NLR) family, detect stress, danger stimuli, and pathogen-associated molecular patterns. We report that the eicosanoid 15-deoxy-Δ(12,14)-PGJ2 (15d-PGJ2) and related cyclopentenone PGs inhibit caspase-1 activation by the NLR family leucine-rich repeat protein (NLRP)1 and NLRP3 inflammasomes. This inhibition was independent of the well-characterized role of 15d-PGJ2 as a peroxisome proliferator receptor-γ agonist, its activation of NF erythroid 2-related factor 2, or its anti-inflammatory function as an inhibitor of NF-κB. Instead, 15d-PGJ2 prevents the autoproteolytic activation of caspase-1 and the maturation of IL-1β through induction of a cellular state inhibitory to caspase-1 proteolytic function. The eicosanoid does not directly modify or inactivate the caspase-1 enzyme. Rather, inhibition is dependent on de novo protein synthesis. In a mouse peritonitis model of gout, using monosodium urate crystals to activate NLRP3, 15d-PGJ2 caused a significant inhibition of cell recruitment and associated IL-1β release. Furthermore, in a murine anthrax infection model, 15d-PGJ2 reversed anthrax lethal toxin-mediated NLRP1-dependent resistance. The findings reported in this study suggest a novel mechanism for the anti-inflammatory properties of the cyclopentenone PGs through inhibition of caspase-1 and the inflammasome.
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Affiliation(s)
- Nolan K Maier
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
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Moayeri M, Leysath CE, Tremblay JM, Vrentas C, Crown D, Leppla SH, Shoemaker CB. A heterodimer of a VHH (variable domains of camelid heavy chain-only) antibody that inhibits anthrax toxin cell binding linked to a VHH antibody that blocks oligomer formation is highly protective in an anthrax spore challenge model. J Biol Chem 2015; 290:6584-95. [PMID: 25564615 DOI: 10.1074/jbc.m114.627943] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Anthrax disease is caused by a toxin consisting of protective antigen (PA), lethal factor, and edema factor. Antibodies against PA have been shown to be protective against the disease. Variable domains of camelid heavy chain-only antibodies (VHHs) with affinity for PA were obtained from immunized alpacas and screened for anthrax neutralizing activity in macrophage toxicity assays. Two classes of neutralizing VHHs were identified recognizing distinct, non-overlapping epitopes. One class recognizes domain 4 of PA at a well characterized neutralizing site through which PA binds to its cellular receptor. A second neutralizing VHH (JKH-C7) recognizes a novel epitope. This antibody inhibits conversion of the PA oligomer from "pre-pore" to its SDS and heat-resistant "pore" conformation while not preventing cleavage of full-length 83-kDa PA (PA83) by cell surface proteases to its oligomer-competent 63-kDa form (PA63). The antibody prevents endocytosis of the cell surface-generated PA63 subunit but not preformed PA63 oligomers formed in solution. JKH-C7 and the receptor-blocking VHH class (JIK-B8) were expressed as a heterodimeric VHH-based neutralizing agent (VNA2-PA). This VNA displayed improved neutralizing potency in cell assays and protected mice from anthrax toxin challenge with much better efficacy than the separate component VHHs. The VNA protected virtually all mice when separately administered at a 1:1 ratio to toxin and protected mice against Bacillus anthracis spore infection. Thus, our studies show the potential of VNAs as anthrax therapeutics. Due to their simple and stable nature, VNAs should be amenable to genetic delivery or administration via respiratory routes.
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Affiliation(s)
- Mahtab Moayeri
- From the Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University North Grafton, Massachusetts 01536 and
| | - Clinton E Leysath
- From the Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University North Grafton, Massachusetts 01536 and
| | - Jacqueline M Tremblay
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Catherine Vrentas
- From the Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University North Grafton, Massachusetts 01536 and
| | - Devorah Crown
- From the Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University North Grafton, Massachusetts 01536 and
| | - Stephen H Leppla
- From the Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine at Tufts University North Grafton, Massachusetts 01536 and
| | - Charles B Shoemaker
- Laboratory of Parasitic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892
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Mukherjee J, Tremblay J, Sheoran A, Schmidt D, Vance DJ, Mantis NJ, Moayeri M, Leppla SH, Dmitriev I, Curiel DT, Tzipori S, Shoemaker CB. 148. Variable fragment of heavy chain antibody (VHH)–based neutralizing agents (VNAs) as unconventional and versatile therapeutics for toxin-mediated diseases. Toxicon 2015. [DOI: 10.1016/j.toxicon.2014.11.151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Alfano RW, Leppla SH, Liu S, Bugge TH, Duesbery NS, Frankel AE. Potent inhibition of tumor angiogenesis by the matrix metalloproteinase-activated anthrax lethal toxin: Implications for broad anti-tumor efficacy. Cell Cycle 2014; 7:745-9. [DOI: 10.4161/cc.7.6.5627] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Singh LK, Dhasmana N, Sajid A, Kumar P, Bhaduri A, Bharadwaj M, Gandotra S, Kalia VC, Das TK, Goel AK, Pomerantsev AP, Misra R, Gerth U, Leppla SH, Singh Y. clpC operon regulates cell architecture and sporulation in Bacillus anthracis. Environ Microbiol 2014; 17:855-65. [PMID: 24947607 DOI: 10.1111/1462-2920.12548] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 06/12/2014] [Indexed: 12/29/2022]
Abstract
The clpC operon is known to regulate several processes such as genetic competence, protein degradation and stress survival in bacteria. Here, we describe the role of clpC operon in Bacillus anthracis. We generated knockout strains of the clpC operon genes to investigate the impact of CtsR, McsA, McsB and ClpC deletion on essential processes of B. anthracis. We observed that growth, cell division, sporulation and germination were severely affected in mcsB and clpC deleted strains, while none of deletions affected toxin secretion. Growth defect in these strains was pronounced at elevated temperature. The growth pattern gets restored on complementation of mcsB and clpC in respective mutants. Electron microscopic examination revealed that mcsB and clpC deletion also causes defect in septum formation leading to cell elongation. These vegetative cell deformities were accompanied by inability of mutant strains to generate morphologically intact spores. Higher levels of polyhydroxybutyrate granules accumulation were also observed in these deletion strains, indicating a defect in sporulation process. Our results demonstrate, for the first time, the vital role played by McsB and ClpC in physiology of B. anthracis and open up further interest on this operon, which might be of importance to success of B. anthracis as pathogen.
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Affiliation(s)
- Lalit K Singh
- CSIR-Institute of Genomics and Integrative Biology, Delhi, 110007, India
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Hu Z, Leppla SH, Li B, Elkins CA. Antibodies specific for nucleic acids and applications in genomic detection and clinical diagnostics. Expert Rev Mol Diagn 2014; 14:895-916. [PMID: 25014728 DOI: 10.1586/14737159.2014.931810] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Detection of nucleic acids using antibodies is uncommon. This is in part because nucleic acids are poor immunogens and it is difficult to elicit antibodies having high affinity to each type of nucleic acid while lacking cross-reactivity to others. We describe the origins and applications of a variety of anti-nucleic acid antibodies, including ones reacting with modified nucleosides and nucleotides, single-stranded DNA, double-stranded DNA, RNA, DNA:RNA hybrids, locked-nucleic acids or peptide nucleic acid:nucleic acid hybrids. Carefully selected antibodies can be excellent reagents for detecting bacteria, viruses, small RNAs, microRNAs, R-loops, cancer cells, stem cells, apoptotic cells and so on. The detection may be sensitive, simple, rapid, specific, reproducible, quantitative and cost-effective. Current microarray and diagnostic methods that depend on cDNA or cRNA can be replaced by using antibody detection of nucleic acids. Therefore, development should be encouraged to explore new utilities and create a robust arsenal of new anti-nucleic acid antibodies.
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Affiliation(s)
- Zonglin Hu
- Winchester Engineering & Analytical Center, Office of Regulatory Affairs, US Food and Drug Administration, 109 Holton Street, Winchester, MA 01890, USA
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Phillips DD, Garboczi DN, Singh K, Hu Z, Leppla SH, Leysath CE. The sub-nanomolar binding of DNA-RNA hybrids by the single-chain Fv fragment of antibody S9.6. J Mol Recognit 2014; 26:376-81. [PMID: 23784994 DOI: 10.1002/jmr.2284] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/25/2013] [Accepted: 04/26/2013] [Indexed: 11/12/2022]
Abstract
The monoclonal antibody S9.6 binds DNA-RNA hybrids with high affinity, making it useful in research and diagnostic applications, such as in microarrays and in the detection of R-loops. A single-chain variable fragment (scFv) of S9.6 was produced, and its affinities for various synthetic nucleic acid hybrids were measured by surface plasmon resonance (SPR). S9.6 exhibits dissociation constants of approximately 0.6 nM for DNA-RNA and, surprisingly, 2.7 nM for RNA-RNA hybrids that are AU-rich. The affinity of the S9.6 scFv did not appear to be strongly influenced by various buffer conditions or by ionic strength below 500 mM NaCl. The smallest epitope that was strongly bound by the S9.6 scFv contained six base pairs of DNA-RNA hybrid. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Damilola D Phillips
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
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Bachran C, Gupta PK, Bachran S, Leysath CE, Hoover B, Fattah RJ, Leppla SH. Reductive methylation and mutation of an anthrax toxin fusion protein modulates its stability and cytotoxicity. Sci Rep 2014; 4:4754. [PMID: 24755540 PMCID: PMC3996465 DOI: 10.1038/srep04754] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 04/01/2014] [Indexed: 02/02/2023] Open
Abstract
We characterized an anti-cancer fusion protein consisting of anthrax lethal factor (LF) and the catalytic domain of Pseudomonas exotoxin A by (i) mutating the N-terminal amino acids and by (ii) reductive methylation to dimethylate all lysines. Dimethylation of lysines was achieved quantitatively and specifically without affecting binding of the fusion protein to PA or decreasing the enzymatic activity of the catalytic moiety. Ubiquitination in vitro was drastically decreased for both the N-terminally mutated and dimethylated variants, and both appeared to be slightly more stable in the cytosol of treated cells. The dimethylated variant showed greatly reduced neutralization by antibodies to LF. The two described modifications offer unique advantages such as increased cytotoxic activity and diminished antibody recognition, and thus may be applicable to other therapeutic proteins that act in the cytosol of cells.
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Affiliation(s)
- Christopher Bachran
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
- These authors contributed equally to this work
| | - Pradeep K. Gupta
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
- These authors contributed equally to this work
| | - Silke Bachran
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Clinton E. Leysath
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Benjamin Hoover
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Rasem J. Fattah
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Stephen H. Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
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Liu S, Moayeri M, Leppla SH. Anthrax lethal and edema toxins in anthrax pathogenesis. Trends Microbiol 2014; 22:317-25. [PMID: 24684968 DOI: 10.1016/j.tim.2014.02.012] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 02/23/2014] [Accepted: 02/26/2014] [Indexed: 10/25/2022]
Abstract
The pathophysiological effects resulting from many bacterial diseases are caused by exotoxins released by the bacteria. Bacillus anthracis, a spore-forming bacterium, is such a pathogen, causing anthrax through a combination of bacterial infection and toxemia. B. anthracis causes natural infection in humans and animals and has been a top bioterrorism concern since the 2001 anthrax attacks in the USA. The exotoxins secreted by B. anthracis use capillary morphogenesis protein 2 (CMG2) as the major toxin receptor and play essential roles in pathogenesis during the entire course of the disease. This review focuses on the activities of anthrax toxins and their roles in initial and late stages of anthrax infection.
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Affiliation(s)
- Shihui Liu
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
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McKenzie AT, Pomerantsev AP, Sastalla I, Martens C, Ricklefs SM, Virtaneva K, Anzick S, Porcella SF, Leppla SH. Transcriptome analysis identifies Bacillus anthracis genes that respond to CO2 through an AtxA-dependent mechanism. BMC Genomics 2014; 15:229. [PMID: 24661624 PMCID: PMC3987803 DOI: 10.1186/1471-2164-15-229] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 03/12/2014] [Indexed: 11/30/2022] Open
Abstract
Background Upon infection of a mammalian host, Bacillus anthracis responds to host cues, and particularly to elevated temperature (37°C) and bicarbonate/CO2 concentrations, with increased expression of virulence factors that include the anthrax toxins and extracellular capsular layer. This response requires the presence of the pXO1 virulence plasmid-encoded pleiotropic regulator AtxA. To better understand the genetic basis of this response, we utilized a controlled in vitro system and Next Generation sequencing to determine and compare RNA expression profiles of the parental strain and an isogenic AtxA-deficient strain in a 2 × 2 factorial design with growth environments containing or lacking carbon dioxide. Results We found 15 pXO1-encoded genes and 3 chromosomal genes that were strongly regulated by the separate or synergistic actions of AtxA and carbon dioxide. The majority of the regulated genes responded to both AtxA and carbon dioxide rather than to just one of these factors. Interestingly, we identified two previously unrecognized small RNAs that are highly expressed under physiological carbon dioxide concentrations in an AtxA-dependent manner. Expression levels of the two small RNAs were found to be higher than that of any other gene differentially expressed in response to these conditions. Secondary structure and small RNA-mRNA binding predictions for the two small RNAs suggest that they may perform important functions in regulating B. anthracis virulence. Conclusions A majority of genes on the virulence plasmid pXO1 that are regulated by the presence of either CO2 or AtxA separately are also regulated synergistically in the presence of both. These results also elucidate novel pXO1-encoded small RNAs that are associated with virulence conditions.
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Affiliation(s)
| | - Andrei P Pomerantsev
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD 20892, USA.
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Cirelli KM, Gorfu G, Hassan MA, Printz M, Crown D, Leppla SH, Grigg ME, Saeij JPJ, Moayeri M. Inflammasome sensor NLRP1 controls rat macrophage susceptibility to Toxoplasma gondii. PLoS Pathog 2014; 10:e1003927. [PMID: 24626226 PMCID: PMC3953412 DOI: 10.1371/journal.ppat.1003927] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 12/21/2013] [Indexed: 12/22/2022] Open
Abstract
Toxoplasma gondii is an intracellular parasite that infects a wide range of warm-blooded species. Rats vary in their susceptibility to this parasite. The Toxo1 locus conferring Toxoplasma resistance in rats was previously mapped to a region of chromosome 10 containing Nlrp1. This gene encodes an inflammasome sensor controlling macrophage sensitivity to anthrax lethal toxin (LT) induced rapid cell death (pyroptosis). We show here that rat strain differences in Toxoplasma infected macrophage sensitivity to pyroptosis, IL-1β/IL-18 processing, and inhibition of parasite proliferation are perfectly correlated with NLRP1 sequence, while inversely correlated with sensitivity to anthrax LT-induced cell death. Using recombinant inbred rats, SNP analyses and whole transcriptome gene expression studies, we narrowed the candidate genes for control of Toxoplasma-mediated rat macrophage pyroptosis to four genes, one of which was Nlrp1. Knockdown of Nlrp1 in pyroptosis-sensitive macrophages resulted in higher parasite replication and protection from cell death. Reciprocally, overexpression of the NLRP1 variant from Toxoplasma-sensitive macrophages in pyroptosis-resistant cells led to sensitization of these resistant macrophages. Our findings reveal Toxoplasma as a novel activator of the NLRP1 inflammasome in rat macrophages. Inflammasomes are multiprotein complexes that are a major component of the innate immune system. They contain “sensor” proteins that are responsible for detecting various microbial and environmental danger signals and function by activating caspase-1, an enzyme that mediates cleavage and release of the pro-inflammatory cytokines, IL-1β and IL-18. Toxoplasma gondii is a highly successful protozoan parasite capable of infecting a wide range of host species that have variable levels of resistance. Rat strains have been previously shown to vary in their susceptibility to this parasite. We report here that rat macrophages from different inbred strains also vary in sensitivity to Toxoplasma induced lysis. We find that NLRP1, an inflammasome sensor whose only known agonist is anthrax LT, is also activated by Toxoplasma infection. In rats there is a perfect correlation between NLRP1 sequence and macrophage sensitivity to Toxoplasma-induced rapid cell death, inhibition of parasite proliferation, and IL-1β/IL-18 processing. Nlrp1 genes from sensitive rat macrophages can confer sensitivity to this rapid cell death when expressed in Toxoplasma resistant rat macrophages. Our findings suggest Toxoplasma is a new activator of the NLRP1 inflammasome.
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Affiliation(s)
- Kimberly M. Cirelli
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Gezahegn Gorfu
- Molecular Parasitology Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
| | - Musa A. Hassan
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
| | - Morton Printz
- Department of Pharmacology, University of California-San Diego, La Jolla, California, United States of America
| | - Devorah Crown
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
| | - Stephen H. Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
| | - Michael E. Grigg
- Molecular Parasitology Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
- * E-mail: (MEG); (JPJS); (MM)
| | - Jeroen P. J. Saeij
- Massachusetts Institute of Technology, Department of Biology, Cambridge, Massachusetts, United States of America
- * E-mail: (MEG); (JPJS); (MM)
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, NIAID, NIH, Bethesda, Maryland, United States of America
- * E-mail: (MEG); (JPJS); (MM)
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Maier NK, Crown D, Liu J, Leppla SH, Moayeri M. Arsenic trioxide and other arsenical compounds inhibit the NLRP1, NLRP3, and NAIP5/NLRC4 inflammasomes. J Immunol 2013; 192:763-70. [PMID: 24337744 DOI: 10.4049/jimmunol.1301434] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Inflammasomes are large cytoplasmic multiprotein complexes that activate caspase-1 in response to diverse intracellular danger signals. Inflammasome components termed nucleotide-binding oligomerization domain-like receptor (NLR) proteins act as sensors for pathogen-associated molecular patterns, stress, or danger stimuli. We discovered that arsenicals, including arsenic trioxide and sodium arsenite, inhibited activation of the NLRP1, NLRP3, and NAIP5/NLRC4 inflammasomes by their respective activating signals, anthrax lethal toxin, nigericin, and flagellin. These compounds prevented the autoproteolytic activation of caspase-1 and the processing and secretion of IL-1β from macrophages. Inhibition was independent of protein synthesis induction, proteasome-mediated protein breakdown, or kinase signaling pathways. Arsenic trioxide and sodium arsenite did not directly modify or inhibit the activity of preactivated recombinant caspase-1. Rather, they induced a cellular state inhibitory to both the autoproteolytic and substrate cleavage activities of caspase-1, which was reversed by the reactive oxygen species scavenger N-acetylcysteine but not by reducing agents or NO pathway inhibitors. Arsenicals provided protection against NLRP1-dependent anthrax lethal toxin-mediated cell death and prevented NLRP3-dependent neutrophil recruitment in a monosodium urate crystal inflammatory murine peritonitis model. These findings suggest a novel role in inhibition of the innate immune response for arsenical compounds that have been used as therapeutics for a few hundred years.
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Affiliation(s)
- Nolan K Maier
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
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Abrami L, Brandi L, Moayeri M, Brown MJ, Krantz BA, Leppla SH, van der Goot FG. Hijacking multivesicular bodies enables long-term and exosome-mediated long-distance action of anthrax toxin. Cell Rep 2013; 5:986-96. [PMID: 24239351 DOI: 10.1016/j.celrep.2013.10.019] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 10/01/2013] [Accepted: 10/11/2013] [Indexed: 12/21/2022] Open
Abstract
Anthrax lethal toxin is a classical AB toxin comprised of two components: protective antigen (PA) and lethal factor (LF). Here, we show that following assembly and endocytosis, PA forms a channel that translocates LF, not only into the cytosol, but also into the lumen of endosomal intraluminal vesicles (ILVs). These ILVs can fuse and release LF into the cytosol, where LF can proteolyze and disable host targets. We find that LF can persist in ILVs for days, fully sheltered from proteolytic degradation, both in vitro and in vivo. During this time, ILV-localized LF can be transmitted to daughter cells upon cell division. In addition, LF-containing ILVs can be delivered to the extracellular medium as exosomes. These can deliver LF to the cytosol of naive cells in a manner that is independent of the typical anthrax toxin receptor-mediated trafficking pathway, while being sheltered from neutralizing extracellular factors of the immune system.
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Affiliation(s)
- Laurence Abrami
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Station 19, 1015 Lausanne, Switzerland
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Sastalla I, Fattah R, Coppage N, Nandy P, Crown D, Pomerantsev AP, Leppla SH. The Bacillus cereus Hbl and Nhe tripartite enterotoxin components assemble sequentially on the surface of target cells and are not interchangeable. PLoS One 2013; 8:e76955. [PMID: 24204713 PMCID: PMC3799921 DOI: 10.1371/journal.pone.0076955] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 08/28/2013] [Indexed: 02/06/2023] Open
Abstract
Bacillus cereus is a spore-forming, Gram-positive bacterium commonly associated with outbreaks of food poisoning. It is also known as an opportunistic pathogen causing clinical infections such as bacteremia, meningitis, pneumonia, and gas gangrene-like cutaneous infections, mostly in immunocompromised patients. B. cereus secretes a plethora of toxins of which four are associated with the symptoms of food poisoning. Two of these, the non-hemolytic enterotoxin Nhe and the hemolysin BL (Hbl) toxin, are predicted to be structurally similar and are unique in that they require the combined action of three toxin proteins to induce cell lysis. Despite their dominant role in disease, the molecular mechanism of their toxic function is still poorly understood. We report here that B. cereus strain ATCC 10876 harbors not only genes encoding Nhe, but also two copies of the hbl genes. We identified Hbl as the major secreted toxin responsible for inducing rapid cell lysis both in cultured cells and in an intraperitoneal mouse toxicity model. Antibody neutralization and deletion of Hbl-encoding genes resulted in significant reductions of cytotoxic activity. Microscopy studies with Chinese Hamster Ovary cells furthermore showed that pore formation by both Hbl and Nhe occurs through a stepwise, sequential binding of toxin components to the cell surface and to each other. This begins with binding of Hbl-B or NheC to the eukaryotic membrane, and is followed by the recruitment of Hbl-L1 or NheB, respectively, followed by the corresponding third protein. Lastly, toxin component complementation studies indicate that although Hbl and Nhe can be expressed simultaneously and are predicted to be structurally similar, they are incompatible and cannot complement each other.
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Affiliation(s)
- Inka Sastalla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
| | - Rasem Fattah
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nicole Coppage
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Poulomi Nandy
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Devorah Crown
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Andrei P. Pomerantsev
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Stephen H. Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
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