1
|
Zarei-Mehrvarz E, Fahimirad S, Ghaznavi-Rad E, Abbasian SS, Abtahi H. The LL-37 Antimicrobial Peptide as a Treatment for Systematic Infection of Acinetobacter baumannii in a Mouse Model. Protein Pept Lett 2023; 30:44-53. [PMID: 36177621 DOI: 10.2174/0929866529666220929160704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 06/27/2022] [Accepted: 06/27/2022] [Indexed: 11/22/2022]
Abstract
BACKGROUND The antimicrobial peptides (AMPs) played a critical role in the innate immunity of the host and are considered natural sources illustrating a broad-spectrum antimicrobial activity with high specificity and low cytotoxicity. AMPs generally possess a net positive charge and have amphipathic structures. Thus, AMPs can bind and interact with negatively charged bacterial cell membranes, leading to destructive defects in biomembranes and ending in cell death. LL37 is the only human cathelicidin-derived antimicrobial peptide that shows a broad spectrum of antimicrobial activity. MATERIALS AND METHODS To determine the antibacterial efficiency of LL37 in a mouse model of systemic A. baumannii infection, LL37 corresponding gene was expressed in E. coli, purification and refolding situations were optimized. The antimicrobial performance of produced LL-37 against A. baumannii was evaluated in vitro via MIC and Time Kill assays, and its destructive effects on the bacterial cell were confirmed by SEM image. RESULTS The recombinant LL37 showed strong antibacterial function against A. baumannii at 1.5 μg/mL concentration. Time kill assay showed a sharp reduction of cell viability during the first period of exposure, and complete cell death was recorded after 40 min exposure. CONCLUSION Furthermore, in vivo results represented a significant ability of LL37 in the treatment of systematic infected mouse models, and all infected mice receiving LL37 protein survived without no trace of bacteria in their blood samples.
Collapse
Affiliation(s)
- Ehsan Zarei-Mehrvarz
- Molecular and Medicine Research Center, Arak University of Medical Sciences, Arak, Iran
| | - Shohreh Fahimirad
- Molecular and Medicine Research Center, Arak University of Medical Sciences, Arak, Iran
| | - Ehsanollah Ghaznavi-Rad
- Molecular and Medicine Research Center, Arak University of Medical Sciences, Arak, Iran.,Department of Medical Microbiology, Faculty of Medicine, Arak University of Medical Sciences, Arak, Iran
| | | | - Hamid Abtahi
- Molecular and Medicine Research Center, Arak University of Medical Sciences, Arak, Iran
| |
Collapse
|
2
|
O’Brien DK, Ribot WJ, Chabot DJ, Scorpio A, Tobery SA, Jelacic TM, Wu Z, Friedlander AM. The capsule of Bacillus anthracis protects it from the bactericidal activity of human defensins and other cationic antimicrobial peptides. PLoS Pathog 2022; 18:e1010851. [PMID: 36174087 PMCID: PMC9560598 DOI: 10.1371/journal.ppat.1010851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 10/13/2022] [Accepted: 09/04/2022] [Indexed: 12/04/2022] Open
Abstract
During infection, Bacillus anthracis bacilli encounter potent antimicrobial peptides (AMPs) such as defensins. We examined the role that B. anthracis capsule plays in protecting bacilli from defensins and other cationic AMPs by comparing their effects on a fully virulent encapsulated wild type (WT) strain and an isogenic capsule-deficient capA mutant strain. We identified several human defensins and non-human AMPs that were capable of killing B. anthracis. The human alpha defensins 1–6 (HNP-1-4, HD-5-6), the human beta defensins 1–4 (HBD-1-4), and the non-human AMPs, protegrin, gramicidin D, polymyxin B, nisin, and melittin were all capable of killing both encapsulated WT and non-encapsulated capA mutant B. anthracis. However, non-encapsulated capA mutant bacilli were significantly more susceptible than encapsulated WT bacilli to killing by nearly all of the AMPs tested. We demonstrated that purified capsule bound HBD-2, HBD-3, and HNP-1 in an electrophoretic mobility shift assay. Furthermore, we determined that the capsule layer enveloping WT bacilli bound and trapped HBD-3, substantially reducing the amount reaching the cell wall. To assess whether released capsule might also play a protective role, we pre-incubated HBD-2, HBD-3, or HNP-1 with purified capsule before their addition to non-encapsulated capA mutant bacilli. We found that free capsule completely rescued the capA mutant bacilli from killing by HBD-2 and -3 while killing by HNP-1 was reduced to the level observed with WT bacilli. Together, these results suggest an immune evasion mechanism by which the capsule, both that enveloping the bacilli and released fragments, contributes to virulence by binding to and inhibiting the antimicrobial activity of cationic AMPs. Bacillus anthracis causes anthrax after spores infect the skin, respiratory tract, or gastrointestinal tract. Antimicrobial peptides (AMPs), such as defensins, are a first line of host defense that B. anthracis encounters in all of these tissues. B. anthracis bacteria are covered by a capsule that protects them from being engulfed and destroyed by phagocytic immune cells. In this study, we found that the capsule also provides protection from AMPs. An encapsulated B. anthracis strain is resistant to killing by multiple AMPs from humans and other species compared to an otherwise identical strain that is not encapsulated. By binding defensins the capsule surrounding the bacilli reduces the amount that gets to the bacterial cell wall where it can do damage. B. anthracis bacteria release large fragments of capsule in the host during infection and during growth in culture. We found that purified released capsule can bind defensins and reduce killing of non-encapsulated B. anthracis. Thus, both capsule covering the bacteria and capsule shed by the bacteria can contribute to the pathogenicity of B. anthracis by providing protection from AMPs. Our study reveals a new mechanism by which B. anthracis capsule contributes to virulence.
Collapse
Affiliation(s)
- David K. O’Brien
- United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Wilson J. Ribot
- United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Donald J. Chabot
- United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Angelo Scorpio
- United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Steven A. Tobery
- United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Tanya M. Jelacic
- United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
| | - Zhibin Wu
- Institute of Human Virology, University of Maryland Biotechnology Institute, Baltimore, Maryland, United States of America
| | - Arthur M. Friedlander
- United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland, United States of America
- Department of Medicine, Uniformed University of Health Services, Bethesda, Maryland, United States of America
- * E-mail: ,
| |
Collapse
|
3
|
Mercer DK, Torres MDT, Duay SS, Lovie E, Simpson L, von Köckritz-Blickwede M, de la Fuente-Nunez C, O'Neil DA, Angeles-Boza AM. Antimicrobial Susceptibility Testing of Antimicrobial Peptides to Better Predict Efficacy. Front Cell Infect Microbiol 2020; 10:326. [PMID: 32733816 PMCID: PMC7358464 DOI: 10.3389/fcimb.2020.00326] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/29/2020] [Indexed: 12/11/2022] Open
Abstract
During the development of antimicrobial peptides (AMP) as potential therapeutics, antimicrobial susceptibility testing (AST) stands as an essential part of the process in identification and optimisation of candidate AMP. Standard methods for AST, developed almost 60 years ago for testing conventional antibiotics, are not necessarily fit for purpose when it comes to determining the susceptibility of microorganisms to AMP. Without careful consideration of the parameters comprising AST there is a risk of failing to identify novel antimicrobials at a time when antimicrobial resistance (AMR) is leading the planet toward a post-antibiotic era. More physiologically/clinically relevant AST will allow better determination of the preclinical activity of drug candidates and allow the identification of lead compounds. An important consideration is the efficacy of AMP in biological matrices replicating sites of infection, e.g., blood/plasma/serum, lung bronchiolar lavage fluid/sputum, urine, biofilms, etc., as this will likely be more predictive of clinical efficacy. Additionally, specific AST for different target microorganisms may help to better predict efficacy of AMP in specific infections. In this manuscript, we describe what we believe are the key considerations for AST of AMP and hope that this information can better guide the preclinical development of AMP toward becoming a new generation of urgently needed antimicrobials.
Collapse
Affiliation(s)
| | - Marcelo D. T. Torres
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, Penn Institute for Computational Science, and Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States
| | - Searle S. Duay
- Department of Chemistry, Institute of Materials Science, University of Connecticut, Storrs, CT, United States
| | - Emma Lovie
- NovaBiotics Ltd, Aberdeen, United Kingdom
| | | | | | - Cesar de la Fuente-Nunez
- Machine Biology Group, Departments of Psychiatry and Microbiology, Institute for Biomedical Informatics, Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, Penn Institute for Computational Science, and Department of Bioengineering, University of Pennsylvania, Philadelphia, PA, United States
| | | | - Alfredo M. Angeles-Boza
- Department of Chemistry, Institute of Materials Science, University of Connecticut, Storrs, CT, United States
| |
Collapse
|
4
|
Antimicrobial Host Defence Peptides: Immunomodulatory Functions and Translational Prospects. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1117:149-171. [DOI: 10.1007/978-981-13-3588-4_10] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
5
|
Affiliation(s)
- Ryan J Blower
- a School of Systems Biology, George Mason University , Manassas , VA , USA
| | - Serguei G Popov
- a School of Systems Biology, George Mason University , Manassas , VA , USA
| | - Monique L van Hoek
- a School of Systems Biology, George Mason University , Manassas , VA , USA
| |
Collapse
|
6
|
Head BM, Rubinstein E, Meyers AFA. Alternative pre-approved and novel therapies for the treatment of anthrax. BMC Infect Dis 2016; 16:621. [PMID: 27809794 PMCID: PMC5094018 DOI: 10.1186/s12879-016-1951-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 10/22/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Bacillus anthracis, the causative agent of anthrax, is a spore forming and toxin producing rod-shaped bacterium that is classified as a category A bioterror agent. This pathogenic microbe can be transmitted to both animals and humans. Clinical presentation depends on the route of entry (direct contact, ingestion, injection or aerosolization) with symptoms ranging from isolated skin infections to more severe manifestations such as cardiac or pulmonary shock, meningitis, and death. To date, anthrax is treatable if antibiotics are administered promptly and continued for 60 days. However, if treatment is delayed or administered improperly, the patient's chances of survival are decreased drastically. In addition, antibiotics are ineffective against the harmful anthrax toxins and spores. Therefore, alternative therapeutics are essential. In this review article, we explore and discuss advances that have been made in anthrax therapy with a primary focus on alternative pre-approved and novel antibiotics as well as anti-toxin therapies. METHODS A literature search was conducted using the University of Manitoba search engine. Using this search engine allowed access to a greater variety of journals/articles that would have otherwise been restricted for general use. In order to be considered for discussion for this review, all articles must have been published later than 2009. RESULTS The alternative pre-approved antibiotics demonstrated high efficacy against B. anthracis both in vitro and in vivo. In addition, the safety profile and clinical pharmacology of these drugs were already known. Compounds that targeted underexploited bacterial processes (DNA replication, RNA synthesis, and cell division) were also very effective in combatting B. anthracis. In addition, these novel compounds prevented bacterial resistance. Targeting B. anthracis virulence, more specifically the anthrax toxins, increased the length of which treatment could be administered. CONCLUSIONS Several novel and pre-existing antibiotics, as well as toxin inhibitors, have shown increasing promise. A combination treatment that targets both bacterial growth and toxin production would be ideal and probably necessary for effectively combatting this armed bacterium.
Collapse
Affiliation(s)
- Breanne M. Head
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB R3E 0J9 Canada
| | - Ethan Rubinstein
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB R3E 0J9 Canada
| | - Adrienne F. A. Meyers
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, MB R3E 0J9 Canada
- National Laboratory for HIV Immunology, JC Wilt Infectious Disease Research Centre, Public Health Agency of Canada, Winnipeg, Canada
- Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya
| |
Collapse
|
7
|
Popova TG, Teunis A, Espina V, Liotta LA, Popov SG. Chemokine-Releasing Microparticles Improve Bacterial Clearance and Survival of Anthrax Spore-Challenged Mice. PLoS One 2016; 11:e0163163. [PMID: 27632537 PMCID: PMC5025034 DOI: 10.1371/journal.pone.0163163] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 09/02/2016] [Indexed: 11/18/2022] Open
Abstract
In this study the hydrogel microparticles (MPs) were used to enhance migration of neutrophils in order to improve outcome of anthrax infection in a mouse model. Two MP formulations were tested. In the first one the polyacrylamide gel MPs were chemically coupled with Cibacron Blue (CB) affinity bait. In the second one the bait molecules within the MPs were additionally loaded with neutrophil-attracting chemokines (CKs), human CXCL8 and mouse CCL3. A non-covalent interaction of the bait with the CKs provided their gradual release after administration of the MPs to the host. Mice were challenged into footpads with Bacillus anthracis Sterne spores and given a dose of MPs a few hours before and/or after the spores. Pre-treatment with a single dose of CK-releasing MPs without any additional intervention was able to induce influx of neutrophils to the site of spore inoculation and regional lymph nodes correlating with reduced bacterial burden and decreased inflammatory response in footpads. On average, in two independent experiments, up to 53% of mice survived over 13 days. All control spore-challenged but MP-untreated mice died. The CB-coupled particles were also found to improve survival likely due to the capacity to stimulate release of endogenous CKs, but were less potent at decreasing the inflammatory host response than the CK-releasing MPs. The CK post-treatment did not improve survival compared to the untreated mice which died within 4 to 6 days with a strong inflammation of footpads, indicating quick dissemination of spores though the lymphatics after challenge. This is the first report on the enhanced innate host resistance to anthrax in response to CKs delivered and/or endogenously induced by the MPs.
Collapse
Affiliation(s)
- Taissia G. Popova
- Center for Applied Proteomics and Molecular Medicine, Department of Molecular Microbiology, School of Systems Biology, George Mason University, Manassas, VA, 20110, United States of America
| | - Allison Teunis
- National Center for Biodefense and Infectious Diseases, Department of Molecular Microbiology, School of Systems Biology, George Mason University, Manassas, VA, 20110, United States of America
| | - Virginia Espina
- Center for Applied Proteomics and Molecular Medicine, Department of Molecular Microbiology, School of Systems Biology, George Mason University, Manassas, VA, 20110, United States of America
| | - Lance A. Liotta
- Center for Applied Proteomics and Molecular Medicine, Department of Molecular Microbiology, School of Systems Biology, George Mason University, Manassas, VA, 20110, United States of America
| | - Serguei G. Popov
- National Center for Biodefense and Infectious Diseases, Department of Molecular Microbiology, School of Systems Biology, George Mason University, Manassas, VA, 20110, United States of America
- * E-mail:
| |
Collapse
|
8
|
Teyssières E, Corre JP, Antunes S, Rougeot C, Dugave C, Jouvion G, Claudon P, Mikaty G, Douat C, Goossens PL, Guichard G. Proteolytically Stable Foldamer Mimics of Host-Defense Peptides with Protective Activities in a Murine Model of Bacterial Infection. J Med Chem 2016; 59:8221-32. [DOI: 10.1021/acs.jmedchem.6b00144] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Emilie Teyssières
- Pathogénie
des Toxi-Infections Bactériennes, Institut Pasteur, 28
rue du Docteur Roux, 75724 Paris, France
| | - Jean-Philippe Corre
- Pathogénie
des Toxi-Infections Bactériennes, Institut Pasteur, 28
rue du Docteur Roux, 75724 Paris, France
| | - Stephanie Antunes
- Univ. Bordeaux, CBMN, UMR 5248, Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33607 Pessac, France
- CNRS, CBMN, UMR 5248, F-33600 Pessac, France
| | - Catherine Rougeot
- Laboratoire
de Pharmacologie de la Douleur, Institut Pasteur, 28 rue du Docteur
Roux, 75724 Paris, France
| | - Christophe Dugave
- Institut
de Biologie et de Technologie de Saclay (iBiTec-S), Service de Chimie
Bio-organique et de Marquage, CEA-Saclay, bâtiment 547, 91191 Gif-sur-Yvette, France
| | - Grégory Jouvion
- Institut Pasteur, Histopathologie Humaine et Modèles
Animaux, 75724 Paris, France
- Paris Descartes Université, PRES Sorbonne-Paris-Cité, 75006 Paris, France
| | - Paul Claudon
- Univ. Bordeaux, CBMN, UMR 5248, Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33607 Pessac, France
- CNRS, CBMN, UMR 5248, F-33600 Pessac, France
| | - Guillain Mikaty
- Pathogénie
des Toxi-Infections Bactériennes, Institut Pasteur, 28
rue du Docteur Roux, 75724 Paris, France
| | - Céline Douat
- Univ. Bordeaux, CBMN, UMR 5248, Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33607 Pessac, France
- CNRS, CBMN, UMR 5248, F-33600 Pessac, France
| | - Pierre L. Goossens
- Pathogénie
des Toxi-Infections Bactériennes, Institut Pasteur, 28
rue du Docteur Roux, 75724 Paris, France
- Institut Pasteur, Histopathologie Humaine et Modèles
Animaux, 75724 Paris, France
| | - Gilles Guichard
- Univ. Bordeaux, CBMN, UMR 5248, Institut Européen
de Chimie et Biologie, 2 rue Robert Escarpit, 33607 Pessac, France
- CNRS, CBMN, UMR 5248, F-33600 Pessac, France
| |
Collapse
|
9
|
Schneider VAF, van Dijk A, van der Sar AM, Kraaij MD, Veldhuizen EJA, Haagsman HP. Prophylactic administration of chicken cathelicidin-2 boosts zebrafish embryonic innate immunity. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 60:108-114. [PMID: 26920462 DOI: 10.1016/j.dci.2016.02.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 02/21/2016] [Accepted: 02/22/2016] [Indexed: 06/05/2023]
Abstract
Chicken cathelicidin-2 (CATH-2) is a host defense peptide that exhibits immunomodulatory and antibacterial properties. Here we examined effects of CATH-2 in zebrafish embryos in the absence and presence of infection. Yolk-injection of 0.2-1.5 h post-fertilized (hpf) zebrafish embryos with 2.6 ng/kg CATH-2 increased proliferation of phagocytic cells at 48 hpf by 30%. A lethal infection model was developed to test the prophylactic protective effect of CATH-2 peptide. Embryos (0.2-1.5 hpf) were injected with 2.6 ng/kg CATH-2, challenged with a lethal dose of fluorescently labeled Salmonella enteritidis pGMDs3 at 28 hpf and monitored for survival. Prophylactic treatment with CATH-2 was found to delay infection starting at 22 h post-infection (hpi). At 18-20 hpi, significantly lower (2-fold) fluorescence intensity and decreased bacterial loads were detected in peptide-treated embryos. Thus prophylactic administration of low CATH-2 concentrations confer partial protection in zebrafish embryos by boosting the innate immune system.
Collapse
Affiliation(s)
- Viktoria A F Schneider
- Department of Infectious Diseases and Immunology, Division Molecular Host Defence, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Albert van Dijk
- Department of Infectious Diseases and Immunology, Division Molecular Host Defence, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Astrid M van der Sar
- Department of Medical Microbiology and Infection Control, VU University Medical Center, Amsterdam, The Netherlands
| | - Marina D Kraaij
- Department of Infectious Diseases and Immunology, Division Molecular Host Defence, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Edwin J A Veldhuizen
- Department of Infectious Diseases and Immunology, Division Molecular Host Defence, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Henk P Haagsman
- Department of Infectious Diseases and Immunology, Division Molecular Host Defence, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.
| |
Collapse
|
10
|
Findlay F, Proudfoot L, Stevens C, Barlow PG. Cationic host defense peptides; novel antimicrobial therapeutics against Category A pathogens and emerging infections. Pathog Glob Health 2016; 110:137-47. [PMID: 27315342 DOI: 10.1080/20477724.2016.1195036] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cationic Host Defense Peptides (HDP, also known as antimicrobial peptides) are crucial components of the innate immune system and possess broad-spectrum antibacterial, antiviral, and immunomodulatory activities. They can contribute to the rapid clearance of biological agents through direct killing of the organisms, inhibition of pro-inflammatory mediators such as lipopolysaccharide, and by modulating the inflammatory response to infection. Category A biological agents and materials, as classified by the United States National Institutes for Health, the US Centers for Disease Control and Prevention, and the US Department of Homeland Security, carry the most severe threat in terms of human health, transmissibility, and preparedness. As such, there is a pressing need for novel frontline approaches for prevention and treatment of diseases caused by these organisms, and exploiting the broad antimicrobial activity exhibited by cationic host defense peptides represents an exciting priority area for clinical research. This review will summarize what is known about the antimicrobial and antiviral effects of the two main families of cationic host defense peptides, cathelicidins, and defensins in the context of Category A biological agents which include, but are not limited to; anthrax (Bacillus anthracis), plague (Yersinia pestis), smallpox (Variola major), tularemia (Francisella tularensis). In addition, we highlight priority areas, particularly emerging viral infections, where more extensive research is urgently required.
Collapse
Affiliation(s)
- Fern Findlay
- a School of Life, Sport and Social Sciences , Edinburgh Napier University , Sighthill Campus, Edinburgh EH11 4BN , UK
| | - Lorna Proudfoot
- a School of Life, Sport and Social Sciences , Edinburgh Napier University , Sighthill Campus, Edinburgh EH11 4BN , UK
| | - Craig Stevens
- a School of Life, Sport and Social Sciences , Edinburgh Napier University , Sighthill Campus, Edinburgh EH11 4BN , UK
| | - Peter G Barlow
- a School of Life, Sport and Social Sciences , Edinburgh Napier University , Sighthill Campus, Edinburgh EH11 4BN , UK
| |
Collapse
|
11
|
Dörr A, Kress E, Podschun R, Pufe T, Tauber SC, Brandenburg LO. Intrathecal application of the antimicrobial peptide CRAMP reduced mortality and neuroinflammation in an experimental model of pneumococcal meningitis. J Infect 2015; 71:188-99. [PMID: 25896094 DOI: 10.1016/j.jinf.2015.04.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 03/23/2015] [Accepted: 04/10/2015] [Indexed: 12/23/2022]
Abstract
Antimicrobial peptides (AP) are important components of the innate immune system. Our previous work revealed a higher mortality rate and up-regulation of proinflammatory gene expression as well as glial cell activation in cathelicidin-related antimicrobial peptide (CRAMP)-deficient mice after bacterial meningitis. However, the influence of CRAMP application on the progression of inflammation and its impact on mortality after bacterial meningitis remains unknown. To assess the effects of continuous CRAMP exposure in the brain, C57BL/6 wildtype mice were given intracerebroventricular infusion of CRAMP to investigate the effects on mortality, glial cell activation and inflammation in a mouse model of pneumococcal meningitis using immunohistochemistry and realtime RT-PCR. Our results revealed a decrease of mortality after CRAMP infusion. The intrathecal CRAMP infusion after pneumococcal meningitis resulted in a decreased mRNA expression of pro-inflammatory cytokines, whereas the immune responses including the expression of pattern recognition receptors and chemokines were increased in bacterial meningitis. Taken together, the results support the important role of CRAMP as part of the innate immune response against pathogens in bacterial CNS infections. The APs may be a promising approach for the development of an adjuvant therapy for bacterial meningitis.
Collapse
Affiliation(s)
- Arndt Dörr
- Department of Anatomy and Cell Biology, RWTH Aachen University, Germany
| | - Eugenia Kress
- Department of Anatomy and Cell Biology, RWTH Aachen University, Germany
| | - Rainer Podschun
- Institute for Infection Medicine, University Hospital Schleswig-Holstein, Kiel, Germany
| | - Thomas Pufe
- Department of Anatomy and Cell Biology, RWTH Aachen University, Germany
| | - Simone C Tauber
- Department of Neurology, RWTH University Hospital Aachen, Germany
| | | |
Collapse
|
12
|
Baumann A, Démoulins T, Python S, Summerfield A. Porcine Cathelicidins Efficiently Complex and Deliver Nucleic Acids to Plasmacytoid Dendritic Cells and Can Thereby Mediate Bacteria-Induced IFN-α Responses. THE JOURNAL OF IMMUNOLOGY 2014; 193:364-71. [DOI: 10.4049/jimmunol.1303219] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
|
13
|
Bommineni YR, Pham GH, Sunkara LT, Achanta M, Zhang G. Immune regulatory activities of fowlicidin-1, a cathelicidin host defense peptide. Mol Immunol 2014; 59:55-63. [DOI: 10.1016/j.molimm.2014.01.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 01/03/2014] [Accepted: 01/08/2014] [Indexed: 02/05/2023]
|
14
|
Yee SB, Dyer DN, Twenhafel NA, Pitt MLM. Transient lipopolysaccharide-induced resistance to aerosolized Bacillus anthracis in New Zealand white rabbits. Comp Med 2013; 63:252-61. [PMID: 23759528 PMCID: PMC3690431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 08/21/2012] [Accepted: 12/09/2012] [Indexed: 06/02/2023]
Abstract
Previous studies have demonstrated that prior infection by various bacterial pathogens induces nonspecific resistance to subsequent infection by other gram-negative and gram-positive bacterial pathogens. In the present study, we evaluated whether underlying inflammation enhanced host resistance to inhalational Bacillus anthracis infection in New Zealand White rabbits (SPF; Bordetella- and Pasteurella-free). Accordingly, rabbits were pretreated with either the inflammagen bacterial LPS (60,000 EU/kg), a component of the outer membrane of gram-negative bacteria, or saline (vehicle). Administration of LPS resulted in brief pyrexia and a significant increase in the proinflammatory cytokine TNFα, thus confirming LPS-induced inflammation. At 24 h after LPS treatment, rabbits were exposed to aerosolized B. anthracis spores (Ames strain; approximately 300 LD50). Blood samples collected at various times after challenge were cultured. Compared with their saline-pretreated counterparts, LPS-pretreated, B. anthracis challenged rabbits exhibited delays in 2 biomarkers of B. anthracis infection-anthrax-induced pyrexia (25 h versus 66 h after challenge, respectively) and bacteremia (26 h versus 63 h, respectively)-and survived longer (41 h versus 90 h, respectively). Similar to control animals, all LPS-pretreated, B. anthracis-challenged rabbits exhibited pathology consistent with inhalational anthrax. Taken together, these results suggest that prior or underlying stimulation of the innate immune system induces transient host resistance to subsequent B. anthracis infection in SPF New Zealand white rabbits. In particular, our results emphasize the importance of using animals that are free of underlying infections to prevent confounding data in studies for inhalational anthrax characterization and medical countermeasure evaluation.
Collapse
Affiliation(s)
- Steven B Yee
- Center for Aerobiological Sciences, United States Army Medical Institute of Infectious Diseases, Fort Detrick, Maryland, USA.
| | | | | | | |
Collapse
|
15
|
Flick-Smith HC, Fox MA, Hamblin KA, Richards MI, Jenner DC, Laws TR, Phelps AL, Taylor C, Harding SV, Ulaeto DO, Atkins HS. Assessment of antimicrobial peptide LL-37 as a post-exposure therapy to protect against respiratory tularemia in mice. Peptides 2013; 43:96-101. [PMID: 23500517 DOI: 10.1016/j.peptides.2013.02.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 02/28/2013] [Accepted: 02/28/2013] [Indexed: 11/20/2022]
Abstract
Early activation of the innate immune response is important for protection against infection with Francisella tularensis live vaccine strain (LVS) in mice. The human cathelicidin antimicrobial peptide LL-37 is known to have immunomodulatory properties, and therefore exogenously administered LL-37 may be suitable as an early post-exposure therapy to protect against LVS infection. LL-37 has been evaluated for immunostimulatory activity in uninfected mice and for activity against LVS in macrophage assays and protective efficacy when administered post-challenge in a mouse model of respiratory tularemia. Increased levels of pro-inflammatory cytokine IL-6, chemokines monocyte chemoattractant protein 1 (MCP-1) and CXCL1 with increased neutrophil influx into the lungs were observed in uninfected mice after intranasal administration of LL-37. Following LVS challenge, LL-37 administration resulted in increased IL-6, IL-12 p70, IFNγ and MCP-1 production, a slowing of LVS growth in the lung, and a significant extension of mean time to death compared to control mice. However, protection was transient, with the LL-37 treated mice eventually succumbing to infection. As this short course of nasally delivered LL-37 was moderately effective at overcoming the immunosuppressive effects of LVS infection this suggests that a more sustained treatment regimen may be an effective therapy against this pathogen.
Collapse
Affiliation(s)
- Helen C Flick-Smith
- Biomedical Sciences Department, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, United Kingdom.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
A comprehensive summary of LL-37, the factotum human cathelicidin peptide. Cell Immunol 2012; 280:22-35. [PMID: 23246832 DOI: 10.1016/j.cellimm.2012.11.009] [Citation(s) in RCA: 405] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 11/09/2012] [Accepted: 11/15/2012] [Indexed: 01/01/2023]
Abstract
Cathelicidins are a group of antimicrobial peptides. Since their discovery, it has become clear that they are an exceptional class of peptides, with some members having pleiotropic effects. Not only do they possess an antibacterial, antifungal and antiviral function, they also show a chemotactic and immunostimulatory/-modulatory effect. Moreover, they are capable of inducing wound healing, angiogenesis and modulating apoptosis. Recent insights even indicate for a role of these peptides in cancer. This review provides a comprehensive summary of the most recent and relevant insights concerning the human cathelicidin LL-37.
Collapse
|
17
|
Howard A, O'Donoghue M, Feeney A, Sleator RD. Acinetobacter baumannii: an emerging opportunistic pathogen. Virulence 2012; 3:243-50. [PMID: 22546906 PMCID: PMC3442836 DOI: 10.4161/viru.19700] [Citation(s) in RCA: 453] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Acinetobacter baumannii is an opportunistic bacterial pathogen primarily associated with hospital-acquired infections. The recent increase in incidence, largely associated with infected combat troops returning from conflict zones, coupled with a dramatic increase in the incidence of multidrug-resistant (MDR) strains, has significantly raised the profile of this emerging opportunistic pathogen. Herein, we provide an overview of the pathogen, discuss some of the major factors that have led to its clinical prominence and outline some of the novel therapeutic strategies currently in development.
Collapse
Affiliation(s)
- Aoife Howard
- Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland
| | | | | | | |
Collapse
|
18
|
Expression of either lethal toxin or edema toxin by Bacillus anthracis is sufficient for virulence in a rabbit model of inhalational anthrax. Infect Immun 2012; 80:2414-25. [PMID: 22526673 DOI: 10.1128/iai.06340-11] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The development of therapeutics against biothreats requires that we understand the pathogenesis of the disease in relevant animal models. The rabbit model of inhalational anthrax is an important tool in the assessment of potential therapeutics against Bacillus anthracis. We investigated the roles of B. anthracis capsule and toxins in the pathogenesis of inhalational anthrax in rabbits by comparing infection with the Ames strain versus isogenic mutants with deletions of the genes for the capsule operon (capBCADE), lethal factor (lef), edema factor (cya), or protective antigen (pagA). The absence of capsule or protective antigen (PA) resulted in complete avirulence, while the presence of either edema toxin or lethal toxin plus capsule resulted in lethality. The absence of toxin did not influence the ability of B. anthracis to traffic to draining lymph nodes, but systemic dissemination required the presence of at least one of the toxins. Histopathology studies demonstrated minimal differences among lethal wild-type and single toxin mutant strains. When rabbits were coinfected with the Ames strain and the PA- mutant strain, the toxin produced by the Ames strain was not able to promote dissemination of the PA- mutant, suggesting that toxigenic action occurs in close proximity to secreting bacteria. Taken together, these findings suggest that a major role for toxins in the pathogenesis of anthrax is to enable the organism to overcome innate host effector mechanisms locally and that much of the damage during the later stages of infection is due to the interactions of the host with the massive bacterial burden.
Collapse
|
19
|
Pegylation of antimicrobial peptides maintains the active peptide conformation, model membrane interactions, and antimicrobial activity while improving lung tissue biocompatibility following airway delivery. Antimicrob Agents Chemother 2012; 56:3298-308. [PMID: 22430978 DOI: 10.1128/aac.06335-11] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Antimicrobial peptides (AMPs) have therapeutic potential, particularly for localized infections such as those of the lung. Here we show that airway administration of a pegylated AMP minimizes lung tissue toxicity while nevertheless maintaining antimicrobial activity. CaLL, a potent synthetic AMP (KWKLFKKIFKRIVQRIKDFLR) comprising fragments of LL-37 and cecropin A peptides, was N-terminally pegylated (PEG-CaLL). PEG-CaLL derivatives retained significant antimicrobial activity (50% inhibitory concentrations [IC(50)s] 2- to 3-fold higher than those of CaLL) against bacterial lung pathogens even in the presence of lung lining fluid. Circular dichroism and fluorescence spectroscopy confirmed that conformational changes associated with the binding of CaLL to model microbial membranes were not disrupted by pegylation. Pegylation of CaLL reduced AMP-elicited cell toxicity as measured using in vitro lung epithelial primary cell cultures. Further, in a fully intact ex vivo isolated perfused rat lung (IPRL) model, airway-administered PEG-CaLL did not result in disruption of the pulmonary epithelial barrier, whereas CaLL caused an immediate loss of membrane integrity leading to pulmonary edema. All AMPs (CaLL, PEG-CaLL, LL-37, cecropin A) delivered to the lung by airway administration showed limited (<3%) pulmonary absorption in the IPRL with extensive AMP accumulation in lung tissue itself, a characteristic anticipated to be beneficial for the treatment of pulmonary infections. We conclude that pegylation may present a means of improving the lung biocompatibility of AMPs designed for the treatment of pulmonary infections.
Collapse
|
20
|
Kin NW, Chen Y, Stefanov EK, Gallo RL, Kearney JF. Cathelin-related antimicrobial peptide differentially regulates T- and B-cell function. Eur J Immunol 2011; 41:3006-16. [PMID: 21773974 PMCID: PMC3234162 DOI: 10.1002/eji.201141606] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 06/22/2011] [Accepted: 07/07/2011] [Indexed: 01/30/2023]
Abstract
Mammalian antimicrobial peptides (AMPs) play an important role in host defense via direct antimicrobial activity as well as immune regulation. The mouse cathelin-related antimicrobial peptide (mCRAMP), produced from the mouse gene Camp, is the only mouse cathelicidin identified and the ortholog of the human gene encoding the peptide LL-37. This study tested the hypothesis that mouse B and T cells produce and respond to mCRAMP. We show that all mature mouse B-cell subsets, including follicular (FO), marginal zone (MZ), B1a, and B1b cells, as well as CD4(+) and CD8(+) T cells produce Camp mRNA and mCRAMP protein. Camp(-/-) B cells produced equivalent levels of IgM, IgG3, and IgG2c but less IgG1 and IgE, while Camp(-/-) CD4(+) T cells cultured in Th2-inducing conditions produced more IL-4-expressing cells when compared with WT cells, effects that were reversed upon addition of mCRAMP. In vivo, Camp(-/-) mice immunized with TNP-OVA absorbed in alum produced an enhanced TNP-specific IgG1 response when compared with WT mice. ELISpot analysis revealed increased numbers of TNP-specific IgG1-secreting splenic B cells and FACS analysis revealed increased CD4(+) T-cell IL-4 expression. Our results suggest that mCRAMP differentially regulates B- and T-cell function and implicate mCRAMP in the regulation of adaptive immune responses.
Collapse
Affiliation(s)
- Nicholas W. Kin
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Yao Chen
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Emily K. Stefanov
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Richard L. Gallo
- Division of Dermatology, University of California San Diego, La Jolla, CA, USA
- VA Healthcare System, San Diego, CA, USA
| | - John F. Kearney
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| |
Collapse
|
21
|
Wang J, Wong ESW, Whitley JC, Li J, Stringer JM, Short KR, Renfree MB, Belov K, Cocks BG. Ancient antimicrobial peptides kill antibiotic-resistant pathogens: Australian mammals provide new options. PLoS One 2011; 6:e24030. [PMID: 21912615 PMCID: PMC3166071 DOI: 10.1371/journal.pone.0024030] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Accepted: 07/29/2011] [Indexed: 01/08/2023] Open
Abstract
Background To overcome the increasing resistance of pathogens to existing antibiotics the 10×'20 Initiative declared the urgent need for a global commitment to develop 10 new antimicrobial drugs by the year 2020. Naturally occurring animal antibiotics are an obvious place to start. The recently sequenced genomes of mammals that are divergent from human and mouse, including the tammar wallaby and the platypus, provide an opportunity to discover novel antimicrobials. Marsupials and monotremes are ideal potential sources of new antimicrobials because they give birth to underdeveloped immunologically naïve young that develop outside the sterile confines of a uterus in harsh pathogen-laden environments. While their adaptive immune system develops innate immune factors produced either by the mother or by the young must play a key role in protecting the immune-compromised young. In this study we focus on the cathelicidins, a key family of antimicrobial peptide genes. Principal Finding We identified 14 cathelicidin genes in the tammar wallaby genome and 8 in the platypus genome. The tammar genes were expressed in the mammary gland during early lactation before the adaptive immune system of the young develops, as well as in the skin of the pouch young. Both platypus and tammar peptides were effective in killing a broad range of bacterial pathogens. One potent peptide, expressed in the early stages of tammar lactation, effectively killed multidrug-resistant clinical isolates of Pseudomonas aeruginosa, Klebsiella pneumoniae and Acinetobacter baumannii. Conclusions and Significance Marsupial and monotreme young are protected by antimicrobial peptides that are potent, broad spectrum and salt resistant. The genomes of our distant relatives may hold the key for the development of novel drugs to combat multidrug-resistant pathogens.
Collapse
Affiliation(s)
- Jianghui Wang
- Biosciences Research Division, Department of Primary Industries, Bundoora, Australia
| | - Emily S. W. Wong
- Faculty of Veterinary Sciences, University of Sydney, Sydney, Australia
- Australian Research Council Centre of Excellence in Kangaroo Genomics, Parkville, Australia
| | - Jane C. Whitley
- Biosciences Research Division, Department of Primary Industries, Bundoora, Australia
| | - Jian Li
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Australia
| | - Jessica M. Stringer
- Australian Research Council Centre of Excellence in Kangaroo Genomics, Parkville, Australia
- Department of Zoology, The University of Melbourne, Parkville, Australia
| | - Kirsty R. Short
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Australia
| | - Marilyn B. Renfree
- Australian Research Council Centre of Excellence in Kangaroo Genomics, Parkville, Australia
- Department of Zoology, The University of Melbourne, Parkville, Australia
| | - Katherine Belov
- Faculty of Veterinary Sciences, University of Sydney, Sydney, Australia
- Australian Research Council Centre of Excellence in Kangaroo Genomics, Parkville, Australia
- * E-mail:
| | - Benjamin G. Cocks
- Biosciences Research Division, Department of Primary Industries, Bundoora, Australia
- La Trobe University, Bundoora, Australia
| |
Collapse
|
22
|
Potent antimicrobial peptides with selectivity for Bacillus anthracis over human erythrocytes. Int J Antimicrob Agents 2011; 38:237-42. [PMID: 21741801 DOI: 10.1016/j.ijantimicag.2011.05.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 04/14/2011] [Accepted: 05/09/2011] [Indexed: 11/24/2022]
Abstract
In this study, 39 antimicrobial peptides, most with documented low haemolytic activity and potent efficacy against Gram-negative and Gram-positive bacteria, were evaluated for their haemolytic activity against human red blood cells as well as their antimicrobial activity against Escherichia coli, Burkholderia thailandensis, Bacillus globigii and Bacillus anthracis. The majority of the peptides had a minimum inhibitory concentration (MIC) of <10 μM against B. globigii. However, only eight of these (CaLL, Ci-MAM-A24, LLaMA, Ltc2a, OV-5, papillosin, smapspin and smapspin-G) had a MIC<10 μM against B. anthracis. All except one (papillosin) were ineffective at 100 μM against B. thailandensis and none had potent activity against E. coli. Potent activity against B. anthracis was associated with significant haemolytic activity, but the ratio of the concentration of peptide that caused 50% haemolysis to the concentration that inhibited growth of B. anthracis by 50% (the therapeutic index) varied from 0.8 to 34.2. Two peptides (papillosin and Ltc2a) had a therapeutic index >30 and could be considered as candidates for further development for potential medical countermeasures against anthrax. Although B. globigii has often been used as a non-pathogenic simulant for B. anthracis, in this study it was found that the sensitivity of B. globigii to peptides was not a reliable predictor of the sensitivity of B. anthracis to the same peptides.
Collapse
|
23
|
Abdelmassih M, Planchon V, Anceau C, Mahillon J. Development and validation of stable reference materials for food microbiology using Bacillus cereus and Clostridium perfringens spores. J Appl Microbiol 2011; 110:1524-30. [DOI: 10.1111/j.1365-2672.2011.05007.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
24
|
Dawson RM, Liu CQ. Analogues of peptide SMAP-29 with comparable antimicrobial potency and reduced cytotoxicity. Int J Antimicrob Agents 2011; 37:432-7. [PMID: 21377841 DOI: 10.1016/j.ijantimicag.2011.01.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 01/06/2011] [Accepted: 01/07/2011] [Indexed: 11/19/2022]
Abstract
SMAP-29 (sheep myeloid antimicrobial peptide-29) is a peptide with potent antibacterial properties. However, it is also highly cytotoxic both to human red blood cells (hRBCs) and human embryonic kidney (HEK) cells. In this study, some of the amino acids of SMAP-29 were changed in an attempt to reduce haemolytic activity whilst maintaining high antibacterial efficacy. These analogues, plus other analogues described in the literature with potent antimicrobial activity against Gram-positive bacteria coupled with no or low haemolytic activity, were evaluated for their cytotoxicity (hRBCs and HEK cells) as well as antimicrobial efficacy against two Gram-positive (Bacillus anthracis and Bacillus globigii) and two Gram-negative bacteria (Escherichia coli and Burkholderia thailandensis). The analogues previously described in the literature were found to have low antibacterial and haemolytic activity. Two of the designed analogues had comparable antibacterial efficacy with SMAP-29 against B. anthracis but reduced haemolytic activity and therefore had a therapeutic index that was enhanced 2.3-2.6-fold over that of SMAP-29.
Collapse
Affiliation(s)
- Raymond M Dawson
- DSTO Melbourne, 506 Lorimer Street, Fishermans Bend, VIC 3207, Australia.
| | | |
Collapse
|
25
|
Crawford MA, Burdick MD, Glomski IJ, Boyer AE, Barr JR, Mehrad B, Strieter RM, Hughes MA. Interferon-inducible CXC chemokines directly contribute to host defense against inhalational anthrax in a murine model of infection. PLoS Pathog 2010; 6:e1001199. [PMID: 21124994 PMCID: PMC2987825 DOI: 10.1371/journal.ppat.1001199] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 10/18/2010] [Indexed: 12/29/2022] Open
Abstract
Chemokines have been found to exert direct, defensin-like antimicrobial activity in vitro, suggesting that, in addition to orchestrating cellular accumulation and activation, chemokines may contribute directly to the innate host response against infection. No observations have been made, however, demonstrating direct chemokine-mediated promotion of host defense in vivo. Here, we show that the murine interferon-inducible CXC chemokines CXCL9, CXCL10, and CXCL11 each exert direct antimicrobial effects in vitro against Bacillus anthracis Sterne strain spores and bacilli including disruptions in spore germination and marked reductions in spore and bacilli viability as assessed using CFU determination and a fluorometric assay of metabolic activity. Similar chemokine-mediated antimicrobial activity was also observed against fully virulent Ames strain spores and encapsulated bacilli. Moreover, antibody-mediated neutralization of these CXC chemokines in vivo was found to significantly increase host susceptibility to pulmonary B. anthracis infection in a murine model of inhalational anthrax with disease progression characterized by systemic bacterial dissemination, toxemia, and host death. Neutralization of the shared chemokine receptor CXCR3, responsible for mediating cellular recruitment in response to CXCL9, CXCL10, and CXCL11, was not found to increase host susceptibility to inhalational anthrax. Taken together, our data demonstrate a novel, receptor-independent antimicrobial role for the interferon-inducible CXC chemokines in pulmonary innate immunity in vivo. These data also support an immunomodulatory approach for effectively treating and/or preventing pulmonary B. anthracis infection, as well as infections caused by pathogenic and potentially, multi-drug resistant bacteria including other spore-forming organisms. Innate immunity is critical to host defense and plays a central role in protecting the lungs from respiratory pathogens. Among the mediators important in the innate host response to pulmonary infection are chemokines, proteins originally described for their ability to regulate immune cell trafficking during an inflammatory response. More recently, chemokines have been found to exert direct antimicrobial activity against a broad range of bacteria and fungi in vitro. While these observations suggest chemokines may contribute to host defense by killing microorganisms at local sites of infection through activities not associated with cellular chemokine receptors, the biological relevance of direct chemokine-mediated antimicrobial activity in vivo has not been established. Here we show that the murine chemokines CXCL9, CXCL10, and CXCL11 exert direct antimicrobial effects against B. anthracis in vitro and that neutralization of these CXC chemokines, but not their shared receptor CXCR3, increases host susceptibility to pulmonary B. anthracis infection in vivo. These data provide unique insight into the host mediators important in host-pathogen interaction and pathogenesis of disease and support the emerging concept that host chemokines mediate efficient, pleiotropic roles that include receptor-independent promotion of host defense in vivo.
Collapse
Affiliation(s)
- Matthew A. Crawford
- Department of Medicine, Division of Infectious Diseases, University of Virginia, Charlottesville, Virginia, United States of America
| | - Marie D. Burdick
- Department of Medicine, Division of Pulmonary & Critical Care Medicine, University of Virginia, Charlottesville, Virginia, United States of America
| | - Ian J. Glomski
- Department of Microbiology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Anne E. Boyer
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - John R. Barr
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Borna Mehrad
- Department of Medicine, Division of Pulmonary & Critical Care Medicine, University of Virginia, Charlottesville, Virginia, United States of America
| | - Robert M. Strieter
- Department of Medicine, Division of Pulmonary & Critical Care Medicine, University of Virginia, Charlottesville, Virginia, United States of America
| | - Molly A. Hughes
- Department of Medicine, Division of Infectious Diseases, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
| |
Collapse
|
26
|
Dawson RM, McAllister J, Liu CQ. Characterisation and evaluation of synthetic antimicrobial peptides against Bacillus globigii, Bacillus anthracis and Burkholderia thailandensis. Int J Antimicrob Agents 2010; 36:359-63. [DOI: 10.1016/j.ijantimicag.2010.06.038] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2010] [Revised: 06/15/2010] [Accepted: 06/17/2010] [Indexed: 01/01/2023]
|
27
|
Rooijakkers SHM, Rasmussen SL, McGillivray SM, Bartnikas TB, Mason AB, Friedlander AM, Nizet V. Human transferrin confers serum resistance against Bacillus anthracis. J Biol Chem 2010; 285:27609-13. [PMID: 20615872 DOI: 10.1074/jbc.m110.154930] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The innate immune system in humans consists of both cellular and humoral components that collaborate to eradicate invading bacteria from the body. Here, we discover that the gram-positive bacterium Bacillus anthracis, the causative agent of anthrax, does not grow in human serum. Fractionation of serum by gel filtration chromatography led to the identification of human transferrin as the inhibiting factor. Purified transferrin blocks growth of both the fully virulent encapsulated B. anthracis Ames and the non-encapsulated Sterne strain. Growth inhibition was also observed in serum of wild-type mice but not of hypotransferrinemic mice that only have approximately 1% circulating transferrin levels. We were able to definitely assign the bacteriostatic activity of transferrin to its iron-binding function: neither iron-saturated transferrin nor a recombinant transferrin mutant unable to bind iron could inhibit growth of B. anthracis. Additional iron could restore bacterial growth in human serum. The observation that other important gram-positive pathogens are not inhibited by transferrin suggests they have evolved effective mechanisms to circumvent serum iron deprivation. These findings provide a better understanding of human host defense mechanisms against anthrax and provide a mechanistic basis for the antimicrobial activity of human transferrin.
Collapse
Affiliation(s)
- Suzan H M Rooijakkers
- Department of Pediatrics, University of California, San Diego, La Jolla, California 92093, USA.
| | | | | | | | | | | | | |
Collapse
|
28
|
Goossens PL. Animal models of human anthrax: the Quest for the Holy Grail. Mol Aspects Med 2009; 30:467-80. [PMID: 19665473 DOI: 10.1016/j.mam.2009.07.005] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Accepted: 07/30/2009] [Indexed: 01/13/2023]
Abstract
Anthrax is rare among humans, few data can be collected from infected individuals and they provide a fragmentary view of the dynamics of infection and human host-pathogen interactions. Therefore, the development of animal models is necessary. Anthrax has the particularity of being a toxi-infection, a combination of infection and toxemia. The ideal animal model would explore these two different facets and mimic human disease as much as possible. In the past decades, the main effort has been focused on modelling of inhalational anthrax and the perception of specific aspects of the infection has evolved in recent years. In this review, we consider criteria which can lead to the most appropriate choice of a given animal species for modelling human anthrax. We will highlight the positive input and limitations of different models and show that they are not mutually exclusive. On the contrary, their contribution to anthrax research can be more rewarding when taken in synergy. We will also present a reappraisal of inhalational anthrax and propose reflections on key points, such as portal of entry, connections between mediastinal lymph nodes, pleura and lymphatic drainage.
Collapse
Affiliation(s)
- Pierre L Goossens
- Institut Pasteur, Toxines et Pathogénie Bactérienne, CNRS URA 2172, 28 rue du Docteur Roux, 75724 Paris cedex 15, France.
| |
Collapse
|
29
|
McGillivray SM, Ebrahimi CM, Fisher N, Sabet M, Zhang DX, Chen Y, Haste NM, Aroian RV, Gallo RL, Guiney DG, Friedlander AM, Koehler TM, Nizet V. ClpX contributes to innate defense peptide resistance and virulence phenotypes of Bacillus anthracis. J Innate Immun 2009; 1:494-506. [PMID: 20375606 DOI: 10.1159/000225955] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Accepted: 04/07/2009] [Indexed: 11/19/2022] Open
Abstract
Bacillus anthracis is a National Institute of Allergy and Infectious Diseases Category A priority pathogen and the causative agent of the deadly disease anthrax. We applied a transposon mutagenesis system to screen for novel chromosomally encoded B. anthracis virulence factors. This approach identified ClpX, the regulatory ATPase subunit of the ClpXP protease, as essential for both the hemolytic and proteolytic phenotypes surrounding colonies of B. anthracis grown on blood or casein agar media, respectively. Deletion of clpX attenuated lethality of B. anthracis Sterne in murine subcutaneous and inhalation infection models, and markedly reduced in vivo survival of the fully virulent B. anthracis Ames upon intraperitoneal challenge in guinea pigs. The extracellular proteolytic activity dependent upon ClpX function was linked to degradation of cathelicidin antimicrobial peptides, a front-line effector of innate host defense. B. anthracis lacking ClpX were rapidly killed by cathelicidin and alpha-defensin antimicrobial peptides and lysozyme in vitro. In turn, mice lacking cathelicidin proved hyper-susceptible to lethal infection with wild-type B. anthracis Sterne, confirming cathelicidin to be a critical element of innate defense against the pathogen. We conclude that ClpX is an important factor allowing B. anthracis to subvert host immune clearance mechanisms, and thus represents a novel therapeutic target for prevention or therapy of anthrax, a foremost biodefense concern.
Collapse
Affiliation(s)
- Shauna M McGillivray
- Department of Pediatrics, University of California San Diego, La Jolla, CA 92093-0687, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|