1
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Pruitt EL, Zhang R, Ross DH, Ashford NK, Chen X, Alonzo F, Bush MF, Werth BJ, Xu L. Elucidating the impact of bacterial lipases, human serum albumin, and FASII inhibition on the utilization of exogenous fatty acids by Staphylococcus aureus. mSphere 2023; 8:e0036823. [PMID: 38014966 PMCID: PMC10732024 DOI: 10.1128/msphere.00368-23] [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: 07/06/2023] [Accepted: 10/26/2023] [Indexed: 11/29/2023] Open
Abstract
IMPORTANCE Incorporation of host-derived exogenous fatty acids (eFAs), particularly unsaturated fatty acids (UFAs), by Staphylococcus aureus could affect the bacterial membrane fluidity and susceptibility to antimicrobials. In this work, we found that glycerol ester hydrolase (Geh) is the primary lipase hydrolyzing cholesteryl esters and, to a lesser extent, triglycerides and that human serum albumin (HSA) could serve as a buffer of eFAs, where low levels of HSA facilitate the utilization of eFAs but high levels of HSA inhibit it. The fact that the type II fatty acid synthesis (FASII) inhibitor, AFN-1252, leads to an increase in UFA content even in the absence of eFA suggests that membrane property modulation is part of its mechanism of action. Thus, Geh and/or the FASII system look to be promising targets to enhance S. aureus killing in a host environment by restricting eFA utilization or modulating membrane properties, respectively.
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Affiliation(s)
- Emily L. Pruitt
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Rutan Zhang
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | - Dylan H. Ross
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | | | - Xi Chen
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Matthew F. Bush
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Brian J. Werth
- Department of Pharmacy, University of Washington, Seattle, Washington, USA
| | - Libin Xu
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
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2
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Acosta IC, Alonzo F. The Intersection between Bacterial Metabolism and Innate Immunity. J Innate Immun 2023; 15:782-803. [PMID: 37899025 PMCID: PMC10663042 DOI: 10.1159/000534872] [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: 09/14/2023] [Accepted: 10/25/2023] [Indexed: 10/31/2023] Open
Abstract
BACKGROUND The innate immune system is the first line of defense against microbial pathogens and is essential for maintaining good health. If pathogens breach innate barriers, the likelihood of infection is significantly increased. Many bacterial pathogens pose a threat to human health on account of their ability to evade innate immunity and survive in growth-restricted environments. These pathogens have evolved sophisticated strategies to obtain nutrients as well as manipulate innate immune responses, resulting in disease or chronic infection. SUMMARY The relationship between bacterial metabolism and innate immunity is complex. Although aspects of bacterial metabolism can be beneficial to the host, particularly those related to the microbiota and barrier integrity, others can be harmful. Several bacterial pathogens harness metabolism to evade immune responses and persist during infection. The study of these adaptive traits provides insight into the roles of microbial metabolism in pathogenesis that extend beyond energy balance. This review considers recent studies on bacterial metabolic pathways that promote infection by circumventing several facets of the innate immune system. We also discuss relationships between innate immunity and antibiotics and highlight future directions for research in this field. KEY MESSAGES Pathogenic bacteria have a remarkable capacity to harness metabolism to manipulate immune responses and promote pathogenesis. While we are beginning to understand the multifaceted and complex metabolic adaptations that occur during infection, there is still much to uncover with future research.
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Affiliation(s)
- Ivan C Acosta
- Department of Microbiology and Immunology, University of Illinois at Chicago - College of Medicine, Chicago, Illinois, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, University of Illinois at Chicago - College of Medicine, Chicago, Illinois, USA
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3
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Pruitt EL, Zhang R, Ross DH, Ashford NK, Chen X, Alonzo F, Bush MF, Werth BJ, Xu L. Elucidating the Impact of Bacterial Lipases, Human Serum Albumin, and FASII Inhibition on the Utilization of Exogenous Fatty Acids by Staphylococcus aureus. bioRxiv 2023:2023.06.29.547085. [PMID: 37425828 PMCID: PMC10327171 DOI: 10.1101/2023.06.29.547085] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Staphylococcus aureus only synthesizes straight-chain or branched-chain saturated fatty acids (SCFAs or BCFAs) via the type II fatty acid synthesis (FASII) pathway, but as a highly adaptive pathogen, S. aureus can also utilize host-derived exogenous fatty acids (eFAs), including SCFAs and unsaturated fatty acids (UFAs). S. aureus secretes three lipases, Geh, sal1, and SAUSA300_0641, which could perform the function of releasing fatty acids from host lipids. Once released, the FAs are phosphorylated by the fatty acid kinase, FakA, and incorporated into the bacterial lipids. In this study, we determined the substrate specificity of S. aureus secreted lipases, the effect of human serum albumin (HSA) on eFA incorporation, and the effect of FASII inhibitor, AFN-1252, on eFA incorporation using comprehensive lipidomics. When grown with major donors of fatty acids, cholesteryl esters (CEs) and triglycerides (TGs), Geh was found to be the primary lipase responsible for hydrolyzing CEs, but other lipases could compensate for the function of Geh in hydrolyzing TGs. Lipidomics showed that eFAs were incorporated into all major S. aureus lipid classes and that fatty acid-containing HSA can serve as a source of eFAs. Furthermore, S. aureus grown with UFAs displayed decreased membrane fluidity and increased production of reactive oxygen species (ROS). Exposure to AFN-1252 enhanced UFAs in the bacterial membrane, even without a source of eFAs, indicating a FASII pathway modification. Thus, the incorporation of eFAs alters the S. aureus lipidome, membrane fluidity, and ROS formation, which could affect host-pathogen interactions and susceptibility to membrane-targeting antimicrobials.
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Affiliation(s)
- Emily L. Pruitt
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Rutan Zhang
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | - Dylan H. Ross
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
| | | | - Xi Chen
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago-Stritch School of Medicine, Maywood, Illinois, USA
| | - Matthew F. Bush
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Brian J. Werth
- Department of Pharmacy, University of Washington, Seattle, Washington, USA
| | - Libin Xu
- Department of Medicinal Chemistry, University of Washington, Seattle, Washington, USA
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4
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Cahoon LA, Alejandro‐Navarreto X, Gururaja AN, Light SH, Alonzo F, Anderson WF, Freitag NE. Listeria monocytogenes two component system PieRS regulates secretion chaperones PrsA1 and PrsA2 and enhances bacterial translocation across the intestine. Mol Microbiol 2022; 118:278-293. [PMID: 35943959 PMCID: PMC9545042 DOI: 10.1111/mmi.14967] [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] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 11/30/2022]
Abstract
Listeria monocytogenes (Lm) is a widespread environmental Gram-positive bacterium that can transition into a pathogen following ingestion by a susceptible host. To cross host barriers and establish infection, Lm is dependent upon the regulated secretion and activity of many proteins including PrsA2, a peptidyl-prolyl cis-trans isomerase with foldase activity. PrsA2 contributes to the stability and activity of a number of secreted virulence factors that are required for Lm invasion, replication, and cell-to-cell spread within the infected host. In contrast, a second related secretion chaperone, PrsA1, has thus far no identified contributions to Lm pathogenesis. Here we describe the characterization of a two-component signal transduction system PieRS that regulates the expression of a regulon that includes the secretion chaperones PrsA1 and PrsA2. PieRS regulated gene products are required for bacterial resistance to ethanol exposure and are important for bacterial survival during transit through the gastrointestinal tract. PrsA1 was also found to make a unique contribution to Lm survival in the GI tract, revealing for the first time a non-overlapping requirement for both secretion chaperones PrsA1 and PrsA2 during the process of intra-gastric infection.
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Affiliation(s)
- Laty A. Cahoon
- Department of Microbiology and ImmunologyUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | | | - Avinash N. Gururaja
- Department of Microbiology and ImmunologyUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | - Sam H. Light
- Department of MicrobiologyUniversity of ChicagoChicagoIllinoisUSA
| | - Francis Alonzo
- Department of Microbiology and ImmunologyLoyola UniversityChicagoIllinoisUSA
| | - Wayne F. Anderson
- Center for Genomics and Infectious Diseases, Feinberg School of MedicineNorthwestern UniversityChicagoIllinoisUSA
| | - Nancy E. Freitag
- Department of Microbiology and ImmunologyUniversity of Illinois at ChicagoChicagoIllinoisUSA
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5
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Acosta IC, Alonzo F. Antibiotic treatment ignites a fire that lasts. Cell Host Microbe 2022; 30:897-899. [DOI: 10.1016/j.chom.2022.06.001] [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: 11/16/2022]
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6
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Chen X, Teoh WP, Stock MR, Resko ZJ, Alonzo F. Branched chain fatty acid synthesis drives tissue-specific innate immune response and infection dynamics of Staphylococcus aureus. PLoS Pathog 2021; 17:e1009930. [PMID: 34496007 PMCID: PMC8452012 DOI: 10.1371/journal.ppat.1009930] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [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: 06/28/2021] [Revised: 09/20/2021] [Accepted: 08/30/2021] [Indexed: 12/13/2022] Open
Abstract
Fatty acid-derived acyl chains of phospholipids and lipoproteins are central to bacterial membrane fluidity and lipoprotein function. Though it can incorporate exogenous unsaturated fatty acids (UFA), Staphylococcus aureus synthesizes branched chain fatty acids (BCFA), not UFA, to modulate or increase membrane fluidity. However, both endogenous BCFA and exogenous UFA can be attached to bacterial lipoproteins. Furthermore, S. aureus membrane lipid content varies based upon the amount of exogenous lipid in the environment. Thus far, the relevance of acyl chain diversity within the S. aureus cell envelope is limited to the observation that attachment of UFA to lipoproteins enhances cytokine secretion by cell lines in a TLR2-dependent manner. Here, we leveraged a BCFA auxotroph of S. aureus and determined that driving UFA incorporation disrupted infection dynamics and increased cytokine production in the liver during systemic infection of mice. In contrast, infection of TLR2-deficient mice restored inflammatory cytokines and bacterial burden to wildtype levels, linking the shift in acyl chain composition toward UFA to detrimental immune activation in vivo. In in vitro studies, bacterial lipoproteins isolated from UFA-supplemented cultures were resistant to lipase-mediated ester hydrolysis and exhibited heightened TLR2-dependent innate cell activation, whereas lipoproteins with BCFA esters were completely inactivated after lipase treatment. These results suggest that de novo synthesis of BCFA reduces lipoprotein-mediated TLR2 activation and improves lipase-mediated hydrolysis making it an important determinant of innate immunity. Overall, this study highlights the potential relevance of cell envelope acyl chain repertoire in infection dynamics of bacterial pathogens.
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Affiliation(s)
- Xi Chen
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Wei Ping Teoh
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Madison R. Stock
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Zachary J. Resko
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago–Stritch School of Medicine, Maywood, Illinois, United States of America
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7
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Visvabharathy L, Genardi S, Cao L, He Y, Alonzo F, Berdyshev E, Wang CR. Group 1 CD1-restricted T cells contribute to control of systemic Staphylococcus aureus infection. PLoS Pathog 2020; 16:e1008443. [PMID: 32343740 PMCID: PMC7188215 DOI: 10.1371/journal.ppat.1008443] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [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: 09/25/2019] [Accepted: 02/28/2020] [Indexed: 11/19/2022] Open
Abstract
Staphylococcus aureus (SA) is the causative agent of both skin/soft tissue infections as well as invasive bloodstream infections. Though vaccines have been developed to target both humoral and T cell-mediated immune responses against SA, they have largely failed due to lack of protective efficacy. Group 1 CD1-restricted T cells recognize lipid rather than peptide antigens. Previously found to recognize lipids derived from cell wall of Mycobacterium tuberculosis (Mtb), these cells were associated with protection against Mtb infection in humans. Using a transgenic mouse model expressing human group 1 CD1 molecules (hCD1Tg), we demonstrate that group 1 CD1-restricted T cells can recognize SA-derived lipids in both immunization and infection settings. Systemic infection of hCD1Tg mice showed that SA-specific group 1 CD1-restricted T cell response peaked at 10 days post-infection, and hCD1Tg mice displayed significantly decreased kidney pathology at this time point compared with WT control mice. Immunodominant SA lipid antigens recognized by group 1 CD1-restricted T cells were comprised mainly of cardiolipin and phosphatidyl glycerol, with little contribution from lysyl-phosphatidyl glycerol which is a unique bacterial lipid not present in mammals. Group 1 CD1-restricted T cell lines specific for SA lipids also conferred protection against SA infection in the kidney after adoptive transfer. They were further able to effectively control SA replication in vitro through direct antigen presentation by group 1 CD1-expressing BMDCs. Together, our data demonstrate a previously unknown role for group 1 CD1-restricted SA lipid-specific T cells in the control of systemic MRSA infection.
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Affiliation(s)
- Lavanya Visvabharathy
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America
| | - Samantha Genardi
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America
| | - Liang Cao
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America
| | - Ying He
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America
| | - Francis Alonzo
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University, Maywood, United States of America
| | - Evgeny Berdyshev
- Department of Medicine, National Jewish Health, Denver, United States of America
| | - Chyung-Ru Wang
- Department of Microbiology and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, United States of America
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8
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Chan R, Buckley PT, O'Malley A, Sause WE, Alonzo F, Lubkin A, Boguslawski KM, Payne A, Fernandez J, Strohl WR, Whitaker B, Lynch AS, Torres VJ. Identification of biologic agents to neutralize the bicomponent leukocidins of Staphylococcus aureus. Sci Transl Med 2020; 11:11/475/eaat0882. [PMID: 30651319 DOI: 10.1126/scitranslmed.aat0882] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 01/22/2018] [Accepted: 12/17/2018] [Indexed: 12/12/2022]
Abstract
A key aspect underlying the severity of infections caused by Staphylococcus aureus is the abundance of virulence factors that the pathogen uses to thwart critical components of the human immune response. One such mechanism involves the destruction of host immune cells by cytolytic toxins secreted by S. aureus, including five bicomponent leukocidins: PVL, HlgAB, HlgCB, LukED, and LukAB. Purified leukocidins can lyse immune cells ex vivo, and systemic injections of purified LukED or HlgAB can acutely kill mice. Here, we describe the generation and characterization of centyrins that bind S. aureus leukocidins with high affinity and protect primary human immune cells from toxin-mediated cytolysis. Centyrins are small protein scaffolds derived from the fibronectin type III-binding domain of the human protein tenascin-C. Although centyrins are potent in tissue culture assays, their short serum half-lives limit their efficacies in vivo. By extending the serum half-lives of centyrins through their fusion to an albumin-binding consensus domain, we demonstrate the in vivo efficacy of these biologics in a murine intoxication model and in models of both prophylactic and therapeutic treatment of live S. aureus systemic infections. These biologics that target S. aureus virulence factors have potential for treating and preventing serious staphylococcal infections.
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Affiliation(s)
- Rita Chan
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Peter T Buckley
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - Aidan O'Malley
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - William E Sause
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Francis Alonzo
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Ashira Lubkin
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Kristina M Boguslawski
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA
| | - Angela Payne
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - Jeffrey Fernandez
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - William R Strohl
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - Brian Whitaker
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA
| | - Anthony Simon Lynch
- Janssen Research & Development, 1400 McKean Road, Spring House, PA, 19477, USA.
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, Alexandria Center for Life Science, 430 East 29th Street, New York, NY 10016, USA.
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9
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Talley S, Kalinina O, Winek M, Paik W, Cannon AR, Alonzo F, Choudhry MA, Knight KL, Campbell EM. A Caspase-1 Biosensor to Monitor the Progression of Inflammation In Vivo. J I 2019; 203:2497-2507. [DOI: 10.4049/jimmunol.1900619] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 08/21/2019] [Indexed: 12/22/2022]
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10
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Paik W, Alonzo F, Knight KL. Probiotic exopolysaccharide protects mice from acute Staphylococcus aureus bloodstream infection, reducing bacterial burden and limiting inflammation. The Journal of Immunology 2019. [DOI: 10.4049/jimmunol.202.supp.190.47] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
Staphylococcus aureus causes severe systemic infection with high mortality. We previously showed that the probiotic Bacillus subtilis, produces an exopolysaccharide (EPS) that induces anti-inflammatory M2 macrophages. We used a lethal S. aureus bloodstream infection model, and found that mice treated with EPS prior to infection survived, and had reduced bacterial burden in the liver and spleen, as well as reduced levels of inflammatory cytokines. We showed that the EPS-induced M2 macrophages inhibited the growth of S. aureus in vitro, and by using an inhibitor of reactive oxygen species (ROS), we found that the growth inhibition of S. aureus was mediated by ROS, an M1-like property. However, these macrophages retained the M2-like capacity to inhibit proinflammatory activation of T cells by S. aureus superantigen. To test if the reduction in proinflammatory cytokines in EPS-treated mice during infection is due to anti-inflammatory effects of EPS rather than to the reduced bacterial load, we isolated splenocytes from EPS-treated mice and stimulated them with S. aureus ex vivo. We found that levels of IFN-γ, KC, and IL-6 were decreased, whereas the production of IL-10 was increased, indicating that the decrease in inflammation by EPS is not solely due to reduction in bacterial load. We suggest that the EPS-induced M2 macrophages represent “hybrid” macrophages capable of both M1- and M2-like functions and could be used to protect hosts from lethal S. aureus infection by bolstering anti-bacterial immunity, while simultaneously limiting inflammation.
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11
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Lubkin A, Lee WL, Alonzo F, Wang C, Aligo J, Keller M, Girgis NM, Reyes-Robles T, Chan R, O'Malley A, Buckley P, Vozhilla N, Vasquez MT, Su J, Sugiyama M, Yeung ST, Coffre M, Bajwa S, Chen E, Martin P, Kim SY, Loomis C, Worthen GS, Shopsin B, Khanna KM, Weinstock D, Lynch AS, Koralov SB, Loke P, Cadwell K, Torres VJ. Staphylococcus aureus Leukocidins Target Endothelial DARC to Cause Lethality in Mice. Cell Host Microbe 2019; 25:463-470.e9. [PMID: 30799265 DOI: 10.1016/j.chom.2019.01.015] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/24/2018] [Accepted: 01/23/2019] [Indexed: 01/16/2023]
Abstract
The pathogenesis of Staphylococcus aureus is thought to depend on the production of pore-forming leukocidins that kill leukocytes and lyse erythrocytes. Two leukocidins, Leukocidin ED (LukED) and γ-Hemolysin AB (HlgAB), are necessary and sufficient to kill mice upon infection and toxin challenge. We demonstrate that LukED and HlgAB cause vascular congestion and derangements in vascular fluid distribution that rapidly cause death in mice. The Duffy antigen receptor for chemokines (DARC) on endothelial cells, rather than leukocytes or erythrocytes, is the critical target for lethality. Consistent with this, LukED and HlgAB injure primary human endothelial cells in a DARC-dependent manner, and mice with DARC-deficient endothelial cells are resistant to toxin-mediated lethality. During bloodstream infection in mice, DARC targeting by S. aureus causes increased tissue damage, organ dysfunction, and host death. The potential for S. aureus leukocidins to manipulate vascular integrity highlights the importance of these virulence factors.
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Affiliation(s)
- Ashira Lubkin
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Warren L Lee
- Keenan Research Centre, St Michael's Hospital, 30 Bond Street, Toronto, ON M5B 1W8, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
| | - Francis Alonzo
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Changsen Wang
- Keenan Research Centre, St Michael's Hospital, 30 Bond Street, Toronto, ON M5B 1W8, Canada
| | - Jason Aligo
- Janssen Research & Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - Matthew Keller
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA; Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Natasha M Girgis
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Tamara Reyes-Robles
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Rita Chan
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Aidan O'Malley
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Peter Buckley
- Janssen Research & Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - Nikollaq Vozhilla
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Marilyn T Vasquez
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Johnny Su
- Keenan Research Centre, St Michael's Hospital, 30 Bond Street, Toronto, ON M5B 1W8, Canada
| | - Michael Sugiyama
- Keenan Research Centre, St Michael's Hospital, 30 Bond Street, Toronto, ON M5B 1W8, Canada
| | - Stephen T Yeung
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Maryaline Coffre
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Sofia Bajwa
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - Eric Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Patricia Martin
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Sang Y Kim
- Department of Pathology, New York University School of Medicine, New York, NY, USA; Office of Collaborative Sciences, NYU School of Medicine, New York, NY, USA; Department of Pathology, NYU School of Medicine, New York, NY, USA
| | - Cynthia Loomis
- Department of Pathology, New York University School of Medicine, New York, NY, USA; Office of Collaborative Sciences, NYU School of Medicine, New York, NY, USA; Department of Pathology, NYU School of Medicine, New York, NY, USA
| | - G Scott Worthen
- Department of Pediatrics, University of Pennsylvania, Philadelphia, PA, USA; Division of Neonatology, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Bo Shopsin
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA; Division of Infectious Diseases, Department of Medicine, NYU School of Medicine, New York, NY 10016, USA
| | - Kamal M Khanna
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Daniel Weinstock
- Janssen Research & Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - Anthony Simon Lynch
- Janssen Research & Development LLC, 1400 McKean Road, Spring House, PA 19477, USA
| | - Sergei B Koralov
- Department of Pathology, New York University School of Medicine, New York, NY, USA
| | - P'ng Loke
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Ken Cadwell
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA; Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
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12
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Adam-Guillermin C, Hertal-Aas T, Oughton D, Blanchard L, Alonzo F, Armant O, Horemans N. Radiosensitivity and transgenerational effects in non-human species. Ann ICRP 2018; 47:327-341. [PMID: 29745724 DOI: 10.1177/0146645318756844] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [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: 01/08/2023]
Abstract
The ALLIANCE working group on effects of ionising radiation on wildlife brings together European researchers to work on the topics of radiosensitivity and transgenerational effects in non-human biota. Differences in radiation sensitivity across species and phyla are poorly understood, but have important implications for understanding the overall effects of radiation and for radiation protection; for example, sensitive species may require special attention in monitoring and radiation protection, and differences in sensitivity between species also lead to overall effects at higher levels (community, ecosystem), since interactions between species can be altered. Hence, understanding the mechanisms of interspecies radiation sensitivity differences may help to clarify mechanisms underpinning intraspecies variation. Differences in sensitivity may only be revealed when organisms are exposed to ionising radiation over several generations. This issue of potential long-term or hereditary effects for both humans and wildlife exposed to low doses of ionising radiation is a major concern. Animal and plant studies suggest that gamma irradiation can lead to observable effects in the F1 generation that are not attributable to inheritance of a rare stable DNA mutation. Several studies have provided evidence of an increase in genomic instability detected in germ or somatic cells of F1 organisms from exposed F0 organisms. This can lead to induced radiosensitivity, and can result in phenotypic effects or lead to reproductive effects and teratogenesis. In particular, studies have been conducted to understand the possible role of epigenetic modifications, such as DNA methylation, histone modifications, or expression of non-coding RNAs in radiosensitivity, as well as in adaptation effects. As such, research using biological models in which the relative contribution of genetic and epigenetic processes can be elucidated is highly valuable.
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Affiliation(s)
- C Adam-Guillermin
- a Institut de Radioprotection et de Sûreté Nucléaire, PSE-ENV/SRTE/LECO, Cadarache, Saint Paul Lez Durance, France
| | | | - D Oughton
- b Norwegian University of Life Sciences, Norway
| | - L Blanchard
- c Commissariat à l'énergie atomique et aux énergies alternatives, France.,d Centre national de la recherche scientifique, France.,e Aix-Marseille Université, France
| | - F Alonzo
- a Institut de Radioprotection et de Sûreté Nucléaire, PSE-ENV/SRTE/LECO, Cadarache, Saint Paul Lez Durance, France
| | - O Armant
- a Institut de Radioprotection et de Sûreté Nucléaire, PSE-ENV/SRTE/LECO, Cadarache, Saint Paul Lez Durance, France
| | - N Horemans
- f Belgian Nuclear Research Centre, Belgium
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13
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Paik W, Alonzo F, Knight KL. Protection from lethal Staphylococcus aureus infection by probiotic exopolysaccharide. The Journal of Immunology 2018. [DOI: 10.4049/jimmunol.200.supp.117.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Staphylococcus aureus is a bacterium that causes severe systemic infection with high mortality. Antibiotic resistance poses major problems for treatment of S. aureus infections, and novel therapeutics are needed. We previously showed that the probiotic Bacillus subtilis, produces an exopolysaccharide (EPS) that induces anti-inflammatory M2 macrophages. Transfer of EPS-induced M2 macrophages to naïve mice protects them from colitis due to an enteric pathogen. We tested if EPS could also protect from lethal S. aureus bloodstream infection. We treated mice with EPS before infection, and found that they survived and had reduced bacterial burden in the liver, and reduced levels of systemic inflammatory cytokines. We sought to determine the mechanism by which EPS protected the mice, and found that the EPS-induced M2 macrophages not only take-up S. aureus, but also inhibit the growth of S. aureus. We used an inhibitor of reactive oxygen species (ROS), and found that the growth inhibition of S. aureus by M2 macrophages was abrogated. In addition, we found that these M2 macrophages retain the capacity to inhibit activation of T cells by S. aureus supernatants which contain superantigens and numerous pro-inflammatory molecules. We suggest that the EPS-induced M2 macrophages represent “hybrid” macrophages capable of both M1- and M2-like functions, and could be used to protect hosts from lethal S. aureus infection by bolstering anti-bacterial immunity, while simultaneously limiting inflammation.
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14
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Laczkovich I, Teoh WP, Flury S, Grayczyk JP, Zorzoli A, Alonzo F. Increased flexibility in the use of exogenous lipoic acid by Staphylococcus aureus. Mol Microbiol 2018; 109:150-168. [PMID: 29660187 DOI: 10.1111/mmi.13970] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2018] [Indexed: 02/06/2023]
Abstract
Lipoic acid is a cofactor required for intermediary metabolism that is either synthesized de novo or acquired from environmental sources. The bacterial pathogen Staphylococcus aureus encodes enzymes required for de novo biosynthesis, but also encodes two ligases, LplA1 and LplA2, that are sufficient for lipoic acid salvage during infection. S. aureus also encodes two H proteins, GcvH of the glycine cleavage system and the homologous GcvH-L encoded in an operon with LplA2. GcvH is a recognized conduit for lipoyl transfer to α-ketoacid dehydrogenase E2 subunits, while the function of GcvH-L remains unclear. The potential to produce two ligases and two H proteins is an unusual characteristic of S. aureus that is unlike most other Gram positive Firmicutes and might allude to an expanded pathway of lipoic acid acquisition in this microorganism. Here, we demonstrate that LplA1 and LplA2 facilitate lipoic acid salvage by differentially targeting lipoyl domain-containing proteins; LplA1 targets H proteins and LplA2 targets α-ketoacid dehydrogenase E2 subunits. Furthermore, GcvH and GcvH-L both facilitate lipoyl relay to E2 subunits. Altogether, these studies identify an expanded mode of lipoic acid salvage used by S. aureus and more broadly underscore the importance of bacterial adaptations when faced with nutritional limitation.
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Affiliation(s)
- Irina Laczkovich
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - Wei Ping Teoh
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - Sarah Flury
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - James P Grayczyk
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - Azul Zorzoli
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago - Stritch School of Medicine, 2160 S. First Avenue, Maywood, IL, 60153, USA
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15
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Abstract
Regulation of Th17 and Th1 cell responses against intracellular pathogens, including Listeria monocytogenes (L. m), is critical to limit inflammation-induced tissue damage. We recently demonstrated the ability of P. UF1 bacterium derived from the intestinal bacterial commensals of preterm infants fed human breast milk to significantly mitigate pathogen-induced inflammation limiting colonic tissue damage. Here we further elucidated the potential of P. UF1 to also regulate innate and T cells, particularly Th17 and Th1 cells, against systemic L. m infection. Data demonstrate that P. UF1 not only robustly regulated protective Th17 and Th1 cells, but also sustained regulatory T cells (Treg cells) resulting in accelerated L. m clearance. Together, regulation of pathogenic inflammation by a novel probiotic bacterium such as P. UF1 may illuminate a new strategy to specifically control Th17-Th1 cells via IL-10+ Treg cells to limit systemic tissue damage induced by intracellular pathogens, including L. m.
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Affiliation(s)
- Natacha Colliou
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, FL, USA,Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine, University of Florida, Gainesville, FL, USA
| | - Yong Ge
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, FL, USA,Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine, University of Florida, Gainesville, FL, USA
| | - Minghao Gong
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, FL, USA,Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine, University of Florida, Gainesville, FL, USA
| | - Mojgan Zadeh
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, FL, USA,Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine, University of Florida, Gainesville, FL, USA
| | - Jing Li
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, FL, USA,Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine, University of Florida, Gainesville, FL, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, IL, USA
| | - Mansour Mohamadzadeh
- Department of Infectious Diseases & Immunology, University of Florida, Gainesville, FL, USA,Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine, University of Florida, Gainesville, FL, USA,CONTACT Mansour Mohamadzadeh Department of Infectious Diseases & Immunology, University of Florida, 2015 SW16th Ave, Building 1017, Gainesville, FL 32608, USA
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16
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Colliou N, Ge Y, Sahay B, Gong M, Zadeh M, Owen JL, Neu J, Farmerie WG, Alonzo F, Liu K, Jones DP, Li S, Mohamadzadeh M. Commensal Propionibacterium strain UF1 mitigates intestinal inflammation via Th17 cell regulation. J Clin Invest 2017; 127:3970-3986. [PMID: 28945202 PMCID: PMC5663347 DOI: 10.1172/jci95376] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [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: 05/26/2017] [Accepted: 08/02/2017] [Indexed: 12/21/2022] Open
Abstract
Consumption of human breast milk (HBM) attenuates the incidence of necrotizing enterocolitis (NEC), which remains a leading and intractable cause of mortality in preterm infants. Here, we report that this diminution correlates with alterations in the gut microbiota, particularly enrichment of Propionibacterium species. Transfaunation of microbiota from HBM-fed preterm infants or a newly identified and cultured Propionibacterium strain, P. UF1, to germfree mice conferred protection against pathogen infection and correlated with profound increases in intestinal Th17 cells. The induction of Th17 cells was dependent on bacterial dihydrolipoamide acetyltransferase (DlaT), a major protein expressed on the P. UF1 surface layer (S-layer). Binding of P. UF1 to its cognate receptor, SIGNR1, on dendritic cells resulted in the regulation of intestinal phagocytes. Importantly, transfer of P. UF1 profoundly mitigated induced NEC-like injury in neonatal mice. Together, these results mechanistically elucidate the protective effects of HBM and P. UF1-induced immunoregulation, which safeguard against proinflammatory diseases, including NEC.
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Affiliation(s)
- Natacha Colliou
- Department of Infectious Diseases and Immunology
- Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine
| | - Yong Ge
- Department of Infectious Diseases and Immunology
- Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine
| | - Bikash Sahay
- Department of Infectious Diseases and Immunology
| | - Minghao Gong
- Department of Infectious Diseases and Immunology
- Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine
| | - Mojgan Zadeh
- Department of Infectious Diseases and Immunology
- Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine
| | | | - Josef Neu
- Division of Neonatology, Department of Pediatrics, and
| | - William G. Farmerie
- Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, Florida, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois, USA
| | - Ken Liu
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Dean P. Jones
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Shuzhao Li
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Mansour Mohamadzadeh
- Department of Infectious Diseases and Immunology
- Division of Gastroenterology, Hepatology & Nutrition, Department of Medicine
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17
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Grayczyk JP, Harvey CJ, Laczkovich I, Alonzo F. A Lipoylated Metabolic Protein Released by Staphylococcus aureus Suppresses Macrophage Activation. Cell Host Microbe 2017; 22:678-687.e9. [PMID: 29056428 DOI: 10.1016/j.chom.2017.09.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [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: 06/08/2017] [Revised: 07/29/2017] [Accepted: 09/08/2017] [Indexed: 11/30/2022]
Abstract
The virulence factors of pathogenic microbes often have single functions that permit immune suppression. However, a proportion possess multiple activities and are considered moonlighting proteins. By examining secreted virulence factors of Staphylococcus aureus, we determine that the bacterial lipoic acid synthetase LipA suppresses macrophage activation. LipA is known to modify the E2 subunit of the metabolic enzyme complex pyruvate dehydrogenase (E2-PDH) with a fatty acid derivative, lipoic acid, yielding the metabolic protein lipoyl-E2-PDH. We demonstrate that lipoyl-E2-PDH is also released by S. aureus and moonlights as a macrophage immunosuppressant by reducing Toll-like receptor 1/2 (TLR1/2) activation by bacterial lipopeptides. A LipA-deficient strain induces heightened pro-inflammatory cytokine production, which is diminished in the absence of TLR2. During murine systemic infection, LipA suppresses pro-inflammatory macrophage activation, rendering these cells inefficient at controlling infection. These observations suggest that bacterial metabolism and immune evasion are linked by virtue of this moonlighting protein.
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Affiliation(s)
- James P Grayczyk
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
| | - Cameron J Harvey
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
| | - Irina Laczkovich
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA.
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18
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Paik W, Paynich ML, Alonzo F, Knight KL. Protection from Staphylococcus aureus sepsis by bacterial exopolysaccharide. The Journal of Immunology 2017. [DOI: 10.4049/jimmunol.198.supp.131.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Sepsis is the most severe presentation of systemic infection with up to 50% mortality rates. The leading etiological agent of sepsis is a Gram-positive bacterium, Staphylococcus aureus. Antibiotics are the only effective therapy for S. aureus sepsis, and widespread resistance to multiple antibiotics is a major concern. Novel therapeutic agents for sepsis are critically needed. We previously showed that exopolysaccharides (EPS) derived from a probiotic bacterium, Bacillus subtilis, protects hosts from inflammatory disease by the induction of anti-inflammatory M2 macrophages. Using a murine systemic infection model, we tested if EPS also has therapeutic potential for S. aureus sepsis. We treated mice with EPS prior to infection with S. aureus and found that weight loss, serum proinflammatory cytokine levels, and bacterial burden in the liver were mitigated compared to vehicle-treated controls. We also found that compared to cells from vehicle-treated mice, peritoneal cells from EPS-treated mice suppress growth of serum-opsonized S. aureus in vitro. We purified peritoneal F4/80-positive macrophages from EPS-treated mice and found that they were responsible for suppressing S. aureus growth by peritoneal cells. We confirmed this by depletion of macrophages from mice using clodronate-loaded liposomes, which mitigated suppression of S. aureus growth by peritoneal cells from EPS-treated mice. We suggest that B. subtilis-derived EPS may be useful for prevention and/or treatment of S. aureus sepsis.
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19
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Zorzoli A, Grayczyk JP, Alonzo F. Staphylococcus aureus Tissue Infection During Sepsis Is Supported by Differential Use of Bacterial or Host-Derived Lipoic Acid. PLoS Pathog 2016; 12:e1005933. [PMID: 27701474 PMCID: PMC5049849 DOI: 10.1371/journal.ppat.1005933] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [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: 07/06/2016] [Accepted: 09/13/2016] [Indexed: 01/31/2023] Open
Abstract
To thrive in diverse environments, bacteria must shift their metabolic output in response to nutrient bioavailability. In many bacterial species, such changes in metabolic flux depend upon lipoic acid, a cofactor required for the activity of enzyme complexes involved in glycolysis, the citric acid cycle, glycine catabolism, and branched chain fatty acid biosynthesis. The requirement of lipoic acid for metabolic enzyme activity necessitates that bacteria synthesize the cofactor and/or scavenge it from environmental sources. Although use of lipoic acid is a conserved phenomenon, the mechanisms behind its biosynthesis and salvage can differ considerably between bacterial species. Furthermore, low levels of circulating free lipoic acid in mammals underscore the importance of lipoic acid acquisition for pathogenic microbes during infection. In this study, we used a genetic approach to characterize the mechanisms of lipoic acid biosynthesis and salvage in the bacterial pathogen Staphylococcus aureus and evaluated the requirements for both pathways during murine sepsis. We determined that S. aureus lipoic acid biosynthesis and salvage genes exist in an arrangement that directly links redox stress response and acetate biosynthesis genes. In addition, we found that lipoic acid salvage is dictated by two ligases that facilitate growth and lipoylation in distinct environmental conditions in vitro, but that are fully compensatory for survival in vivo. Upon infection of mice, we found that de novo biosynthesis or salvage promotes S. aureus survival in a manner that depends upon the infectious site. In addition, when both lipoic acid biosynthesis and salvage are blocked S. aureus is rendered avirulent, implying an inability to induce lipoic acid-independent metabolic programs to promote survival. Together, our results define the major pathways of lipoic acid biosynthesis and salvage in S. aureus and support the notion that bacterial nutrient acquisition schemes are instrumental in dictating pathogen proclivity for an infectious niche. Staphylococcus aureus is a predominant cause of infectious diseases ranging from superficial skin and soft tissue infections to necrotizing pneumonia and sepsis. A remarkable aspect of S. aureus pathobiology lies in the ability of the microorganism to infect a wide variety of host tissues. This infectious promiscuity implies S. aureus exhibits significant adaptability when faced with disparate environments and nutritional deficiencies. In this work, we examine the mechanisms by which S. aureus acquires lipoic acid, a key cofactor involved in maintaining metabolic flux. Our studies determine that S. aureus engages in both de novo biosynthesis and salvage of lipoic acid in a manner that is reminiscent of pathways used by both B. subtilis and L. monocytogenes combined. Further, our work suggests that the complex mechanisms of lipoic acid acquisition dictate the range of tissues S. aureus infects and identifies a lipoic acid salvage enzyme that is dispensable for growth in vitro, but required for S. aureus pathogenesis in vivo. In sum, our results highlight the adaptability of S. aureus in the face of nutrient paucity; the importance of complex nutrient acquisition/biosynthesis pathways in promoting infection; and identify potential novel therapeutic targets that may be effective against S. aureus.
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Affiliation(s)
- Azul Zorzoli
- Department of Microbiology and Immunology, Loyola University Chicago—Stritch School of Medicine, Maywood, Illinois, United States of America
| | - James P. Grayczyk
- Department of Microbiology and Immunology, Loyola University Chicago—Stritch School of Medicine, Maywood, Illinois, United States of America
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago—Stritch School of Medicine, Maywood, Illinois, United States of America
- * E-mail:
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20
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Reyes-Robles T, Lubkin A, Alonzo F, Lacy DB, Torres VJ. Exploiting dominant-negative toxins to combat Staphylococcus aureus pathogenesis. EMBO Rep 2016; 17:780. [PMID: 27139260 DOI: 10.15252/embr.201670010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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21
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Reyes-Robles T, Lubkin A, Alonzo F, Lacy DB, Torres VJ. Exploiting dominant-negative toxins to combat Staphylococcus aureus pathogenesis. EMBO Rep 2016; 17:428-40. [PMID: 26882549 DOI: 10.15252/embr.201540994] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [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: 07/09/2015] [Accepted: 01/05/2016] [Indexed: 12/12/2022] Open
Abstract
Staphylococcus aureus (S. aureus) is a human pathogen that relies on the subversion of host phagocytes to support its pathogenic lifestyle. S. aureus strains can produce up to five beta-barrel, bi-component, pore-forming leukocidins that target and kill host phagocytes. Thus, preventing immune cell killing by these toxins is likely to boost host immunity. Here, we describe the identification of glycine-rich motifs within the membrane-penetrating stem domains of the leukocidin subunits that are critical for killing primary human neutrophils. Remarkably, leukocidins lacking these glycine-rich motifs exhibit dominant-negative inhibitory effects toward their wild-type toxin counterparts as well as other leukocidins. Biochemical and cellular assays revealed that these dominant-negative toxins work by forming mixed complexes that are impaired in pore formation. The dominant-negative leukocidins inhibited S. aureus cytotoxicity toward primary human neutrophils, protected mice from lethal challenge by wild-type leukocidin, and reduced bacterial burden in a murine model of bloodstream infection. Thus, we describe the first example of staphylococcal bi-component dominant-negative toxins and their potential as novel therapeutics to combat S. aureus infection.
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Affiliation(s)
- Tamara Reyes-Robles
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Ashira Lubkin
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - Francis Alonzo
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - D Borden Lacy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
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22
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De S, Bubnys A, Alonzo F, Hyun J, Lary JW, Cole JL, Torres VJ, Olson R. The Relationship between Glycan Binding and Direct Membrane Interactions in Vibrio cholerae Cytolysin, a Channel-forming Toxin. J Biol Chem 2015; 290:28402-28415. [PMID: 26416894 DOI: 10.1074/jbc.m115.675967] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Indexed: 12/19/2022] Open
Abstract
Bacterial pore-forming toxins (PFTs) are structurally diverse pathogen-secreted proteins that form cell-damaging channels in the membranes of host cells. Most PFTs are released as water-soluble monomers that first oligomerize on the membrane before inserting a transmembrane channel. To modulate specificity and increase potency, many PFTs recognize specific cell surface receptors that increase the local toxin concentration on cell membranes, thereby facilitating channel formation. Vibrio cholerae cytolysin (VCC) is a toxin secreted by the human pathogen responsible for pandemic cholera disease and acts as a defensive agent against the host immune system. Although it has been shown that VCC utilizes specific glycan receptors on the cell surface, additional direct contacts with the membrane must also play a role in toxin binding. To better understand the nature of these interactions, we conducted a systematic investigation of the membrane-binding surface of VCC to identify additional membrane interactions important in cell targeting. Through cell-based assays on several human-derived cell lines, we show that VCC is unlikely to utilize high affinity protein receptors as do structurally similar toxins from Staphylococcus aureus. Next, we identified a number of specific amino acid residues that greatly diminish the VCC potency against cells and investigated the interplay between glycan binding and these direct lipid contacts. Finally, we used model membranes to parse the importance of these key residues in lipid and cholesterol binding. Our study provides a complete functional map of the VCC membrane-binding surface and insights into the integration of sugar, lipid, and cholesterol binding interactions.
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Affiliation(s)
- Swastik De
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut 06459
| | - Adele Bubnys
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut 06459
| | - Francis Alonzo
- Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Jinsol Hyun
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut 06459
| | - Jeffrey W Lary
- Biotechnology-Bioservices Center, University of Connecticut, Storrs, Connecticut 06269
| | - James L Cole
- Biotechnology-Bioservices Center, University of Connecticut, Storrs, Connecticut 06269; Department of Molecular and Cell Biology and Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, New York 10016
| | - Rich Olson
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut 06459.
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23
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Garnier-Laplace J, Alonzo F, Adam-Guillermin C. Establishing relationships between environmental exposures to radionuclides and the consequences for wildlife: inferences and weight of evidence. Ann ICRP 2015; 44:295-303. [PMID: 25816277 DOI: 10.1177/0146645315572311] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Ecological risk assessments for radioactive substances are based on a number of inference rules to compensate for knowledge gaps, and generally require the implementation of a weight-of-evidence approach. Until recently, dose (rate)-response relationships used to derive radioprotection criteria for wildlife have mainly relied on laboratory studies from a limited number of species as representatives of biodiversity. There is no doubt that additional knowledge, combined with advanced conceptual and mathematical approaches, is needed to develop general rules and increase confidence when extrapolating from test species to complex biological/ecological systems. Moreover, field data sets based on robust sampling strategies are still needed to validate benchmark values derived from controlled laboratory tests, and to indicate potential indirect ecological effects, if any. This paper illustrates, through several examples, the need for implementing a combined laboratory-field-model approach to obtain science-based benchmark doses (or dose rates) (e.g. screening benchmarks for ecological risk assessments or derived consideration reference levels), based on robust meta-analysis of dose-effect relationships covering ecologically relevant exposure time scales, species, and endpoints.
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Affiliation(s)
- J Garnier-Laplace
- Institute for Radioprotection and Nuclear Safety, IRSN/PRP-ENV/SERIS, Bld 159, Cadarache, 13115 Saint-Paul-lez-Durance, Cedex, France
| | - F Alonzo
- IRSN/PRP-ENV/SERIS/LECO, Laboratory of Ecotoxicology of Radionuclides, France
| | - C Adam-Guillermin
- IRSN/PRP-ENV/SERIS/LECO, Laboratory of Ecotoxicology of Radionuclides, France
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24
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Xayarath B, Alonzo F, Freitag NE. Identification of a peptide-pheromone that enhances Listeria monocytogenes escape from host cell vacuoles. PLoS Pathog 2015; 11:e1004707. [PMID: 25822753 PMCID: PMC4379056 DOI: 10.1371/journal.ppat.1004707] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [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: 07/30/2014] [Accepted: 01/26/2015] [Indexed: 02/05/2023] Open
Abstract
Listeria monocytogenes is a Gram-positive facultative intracellular bacterial pathogen that invades mammalian cells and escapes from membrane-bound vacuoles to replicate within the host cell cytosol. Gene products required for intracellular bacterial growth and bacterial spread to adjacent cells are regulated by a transcriptional activator known as PrfA. PrfA becomes activated following L. monocytogenes entry into host cells, however the signal that stimulates PrfA activation has not yet been defined. Here we provide evidence for L. monocytogenes secretion of a small peptide pheromone, pPplA, which enhances the escape of L. monocytogenes from host cell vacuoles and may facilitate PrfA activation. The pPplA pheromone is generated via the proteolytic processing of the PplA lipoprotein secretion signal peptide. While the PplA lipoprotein is dispensable for pathogenesis, bacteria lacking the pPplA pheromone are significantly attenuated for virulence in mice and have a reduced efficiency of bacterial escape from the vacuoles of nonprofessional phagocytic cells. Mutational activation of PrfA restores virulence and eliminates the need for pPplA-dependent signaling. Experimental evidence suggests that the pPplA peptide may help signal to L. monocytogenes its presence within the confines of the host cell vacuole, stimulating the expression of gene products that contribute to vacuole escape and facilitating PrfA activation to promote bacterial growth within the cytosol.
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Affiliation(s)
- Bobbi Xayarath
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Francis Alonzo
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Nancy E. Freitag
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail:
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Maurer K, Reyes-Robles T, Alonzo F, Durbin J, Torres VJ, Cadwell K. Autophagy mediates tolerance to Staphylococcus aureus alpha-toxin. Cell Host Microbe 2015; 17:429-40. [PMID: 25816775 DOI: 10.1016/j.chom.2015.03.001] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 01/14/2015] [Accepted: 02/05/2015] [Indexed: 12/15/2022]
Abstract
Resistance and tolerance are two defense strategies employed by the host against microbial threats. Autophagy-mediated degradation of bacteria has been extensively described as a major resistance mechanism. Here we find that the dominant function of autophagy proteins during infections with the epidemic community-associated methicillin-resistant Staphylococcus aureus USA300 is to mediate tolerance rather than resistance. Atg16L1 hypomorphic mice (Atg16L1(HM)), which have reduced autophagy, were highly susceptible to lethality in both sepsis and pneumonia models of USA300 infection. Autophagy confers protection by limiting the damage caused by α-toxin, particularly to endothelial cells. Remarkably, Atg16L1(HM) mice display enhanced survival rather than susceptibility upon infection with α-toxin-deficient S. aureus. These results identify an essential role for autophagy in tolerance to Staphylococcal disease and highlight how a single virulence factor encoded by a pathogen can determine whether a given host factor promotes tolerance or resistance.
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Affiliation(s)
- Katie Maurer
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016, USA; Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY 10016, USA
| | - Tamara Reyes-Robles
- Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY 10016, USA; Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - Francis Alonzo
- Department of Microbiology and Immunology, Loyola University Chicago Stritch School of Medicine, Maywood, IL 60153, USA
| | - Joan Durbin
- Department of Pathology, Rutgers-New Jersey Medical School, Newark, NJ 07103, USA
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
| | - Ken Cadwell
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY 10016, USA; Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA.
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Parker D, Ryan CL, Alonzo F, Torres VJ, Planet PJ, Prince AS. CD4+ T cells promote the pathogenesis of Staphylococcus aureus pneumonia. J Infect Dis 2014; 211:835-45. [PMID: 25240171 DOI: 10.1093/infdis/jiu525] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We postulated that the activation of proinflammatory signaling by methicillin-resistant Staphylococcus aureus (MRSA) strain USA300 is a major factor in the pathogenesis of severe pneumonia and a target for immunomodulation. Local activation of T cells in the lung was a conserved feature of multiple strains of S. aureus, in addition to USA300. The pattern of Vβ chain activation was consistent with known superantigens, but deletion of SelX or SEK and SEQ was not sufficient to prevent T-cell activation, indicating the participation of multiple genes. Using Rag2(-/-), Cd4(-/-), and Cd28(-/-) mice, we observed significantly improved clearance of MRSA from the airways and decreased lung pathology, compared with findings for wild-type controls. The improved outcome correlated with decreased production of proinflammatory cytokines (tumor necrosis factor, KC, interleukin 6, and interleukin 1β). Our data suggest that T-cell-mediated hypercytokinemia induced by infection with MRSA strain USA300 contributes to pathogenesis and may be a therapeutic target for improving outcomes of this common infection in a clinical setting.
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Affiliation(s)
- Dane Parker
- Department of Pediatrics, Columbia University
| | | | - Francis Alonzo
- Department of Microbiology, New York University School of Medicine, New York, New York
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, New York
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Benson MA, Ohneck EA, Ryan C, Alonzo F, Smith H, Narechania A, Kolokotronis SO, Satola SW, Uhlemann AC, Sebra R, Deikus G, Shopsin B, Planet PJ, Torres VJ. Evolution of hypervirulence by a MRSA clone through acquisition of a transposable element. Mol Microbiol 2014; 93:664-81. [PMID: 24962815 DOI: 10.1111/mmi.12682] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2014] [Indexed: 01/17/2023]
Abstract
Staphylococcus aureus has evolved as a pathogen that causes a range of diseases in humans. There are two dominant modes of evolution thought to explain most of the virulence differences between strains. First, virulence genes may be acquired from other organisms. Second, mutations may cause changes in the regulation and expression of genes. Here we describe an evolutionary event in which transposition of an IS element has a direct impact on virulence gene regulation resulting in hypervirulence. Whole-genome analysis of a methicillin-resistant S. aureus (MRSA) strain USA500 revealed acquisition of a transposable element (IS256) that is absent from close relatives of this strain. Of the multiple copies of IS256 found in the USA500 genome, one was inserted in the promoter sequence of repressor of toxins (Rot), a master transcriptional regulator responsible for the expression of virulence factors in S. aureus. We show that insertion into the rot promoter by IS256 results in the derepression of cytotoxin expression and increased virulence. Taken together, this work provides new insight into evolutionary strategies by which S. aureus is able to modify its virulence properties and demonstrates a novel mechanism by which horizontal gene transfer directly impacts virulence through altering toxin regulation.
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Affiliation(s)
- Meredith A Benson
- Department of Microbiology, New York University School of Medicine, New York, NY, USA; Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, USA
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Reyes-Robles T, Alonzo F, Kozhaya L, Lacy DB, Unutmaz D, Torres VJ. Staphylococcus aureus leukotoxin ED targets the chemokine receptors CXCR1 and CXCR2 to kill leukocytes and promote infection. Cell Host Microbe 2014; 14:453-9. [PMID: 24139401 DOI: 10.1016/j.chom.2013.09.005] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/21/2013] [Accepted: 09/12/2013] [Indexed: 12/31/2022]
Abstract
The Staphylococcus aureus leukotoxin ED (LukED) is a pore-forming toxin required for the lethality associated with bacteremia in murine models. LukED targets the chemokine receptor CCR5 to kill T lymphocytes, macrophages, and dendritic cells. LukED also kills CCR5-deficient cells, like neutrophils, suggesting the existence of additional cellular receptors. Here, we identify the chemokine receptors CXCR1 and CXCR2 as the targets of LukED on neutrophils. The LukE subunit binds neutrophils in a specific and saturable manner, and this interaction is inhibited by CXCL8, the high-affinity endogenous ligand of CXCR1 and CXCR2. LukED recognition of CXCR1 and CXCR2 promotes the killing of monocytes and neutrophils in vitro. LukED-mediated targeting of CXCR1 and CXCR2(+) cells contributes to S. aureus pathogenesis and facilitates lethality in systemically infected mice. Thus, LukED is a versatile toxin that endows S. aureus with the ability to simultaneously disarm both innate and adaptive compartments of the host immune response.
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Affiliation(s)
- Tamara Reyes-Robles
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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Alonzo F, Torres VJ. Staphylococcus aureus and CCR5: unveiling commonalities in host-pathogen interactions and potential treatment strategies. Future Microbiol 2013; 8:425-8. [PMID: 23534355 DOI: 10.2217/fmb.13.12] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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31
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Hinton TG, Garnier-Laplace J, Vandenhove H, Dowdall M, Adam-Guillermin C, Alonzo F, Barnett C, Beaugelin-Seiller K, Beresford NA, Bradshaw C, Brown J, Eyrolle F, Fevrier L, Gariel JC, Gilbin R, Hertel-Aas T, Horemans N, Howard BJ, Ikäheimonen T, Mora JC, Oughton D, Real A, Salbu B, Simon-Cornu M, Steiner M, Sweeck L, Vives i Batlle J. An invitation to contribute to a strategic research agenda in radioecology. J Environ Radioact 2013; 115:73-82. [PMID: 22885152 DOI: 10.1016/j.jenvrad.2012.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2012] [Accepted: 07/12/2012] [Indexed: 05/21/2023]
Abstract
With intentions of integrating a portion of their respective research efforts into a trans-national programme that will enhance radioecology, eight European organisations recently formed the European Radioecology ALLIANCE (www.er-alliance.org). The ALLIANCE is an Association open to other organisations throughout the world with similar interests in promoting radioecology. The ALLIANCE members recognised that their shared radioecological research could be enhanced by efficiently pooling resources among its partner organizations and prioritising group efforts along common themes of mutual interest. A major step in this prioritisation process was to develop a Strategic Research Agenda (SRA). An EC-funded Network of Excellence in Radioecology, called STAR (Strategy for Allied Radioecology), was formed, in part, to develop the SRA. This document is the first published draft of the SRA. The SRA outlines a suggested prioritisation of research topics in radioecology, with the goal of improving research efficiency and more rapidly advancing the science. It responds to the question: "What topics, if critically addressed over the next 20 years, would significantly advance radioecology?" The three Scientific Challenges presented within the SRA, with their 15 associated research lines, are a strategic vision of what radioecology can achieve in the future. Meeting these challenges will require a directed effort and collaboration with many organisations the world over. Addressing these challenges is important to the advancement of radioecology and in providing scientific knowledge to decision makers. Although the development of the draft SRA has largely been a European effort, the hope is that it will initiate an open dialogue within the international radioecology community and its stakeholders. This is an abbreviated document with the intention of introducing the SRA and inviting contributions from interested stakeholders. Critique and input for improving the SRA are welcomed via a link on the STAR website (www.star-radioecology.org).
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Affiliation(s)
- T G Hinton
- French Institute of Radiation Protection and Nuclear Safety (IRSN), Bat 159, BP 3, 13115 Saint-Paul-Lez-Durance, France.
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32
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Alonzo F, Kozhaya L, Rawlings SA, Reyes-Robles T, DuMont AL, Myszka DG, Landau NR, Unutmaz D, Torres VJ. CCR5 is a receptor for Staphylococcus aureus leukotoxin ED. Nature 2012; 493:51-5. [PMID: 23235831 PMCID: PMC3536884 DOI: 10.1038/nature11724] [Citation(s) in RCA: 218] [Impact Index Per Article: 18.2] [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: 03/28/2012] [Accepted: 10/26/2012] [Indexed: 12/14/2022]
Abstract
Pore-forming toxins are critical virulence factors for many bacterial pathogens and are central to Staphylococcus aureus-mediated killing of host cells. S. aureus encodes pore-forming bi-component leukotoxins that are toxic towards neutrophils, but also specifically target other immune cells. Despite decades since the first description of staphylococcal leukocidal activity, the host factors responsible for the selectivity of leukotoxins towards different immune cells remain unknown. Here we identify the human immunodeficiency virus (HIV) co-receptor CCR5 as a cellular determinant required for cytotoxic targeting of subsets of myeloid cells and T lymphocytes by the S. aureus leukotoxin ED (LukED). We further demonstrate that LukED-dependent cell killing is blocked by CCR5 receptor antagonists, including the HIV drug maraviroc. Remarkably, CCR5-deficient mice are largely resistant to lethal S. aureus infection, highlighting the importance of CCR5 targeting in S. aureus pathogenesis. Thus, depletion of CCR5(+) leukocytes by LukED suggests a new immune evasion mechanism of S. aureus that can be therapeutically targeted.
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Affiliation(s)
- Francis Alonzo
- Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
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Alonzo F, Benson MA, Chen J, Novick RP, Shopsin B, Torres VJ. Staphylococcus aureus leucocidin ED contributes to systemic infection by targeting neutrophils and promoting bacterial growth in vivo. Mol Microbiol 2011; 83:423-35. [PMID: 22142035 DOI: 10.1111/j.1365-2958.2011.07942.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Bloodstream infection with Staphylococcus aureus is common and can be fatal. However, virulence factors that contribute to lethality in S. aureus bloodstream infection are poorly defined. We discovered that LukED, a commonly overlooked leucotoxin, is critical for S. aureus bloodstream infection in mice. We also determined that LukED promotes S. aureus replication in vivo by directly killing phagocytes recruited to sites of haematogenously seeded tissue. Furthermore, we established that murine neutrophils are the primary target of LukED, as the greater virulence of wild-type S. aureus compared with a lukED mutant was abrogated by depleting neutrophils. The in vivo toxicity of LukED towards murine phagocytes is unique among S. aureus leucotoxins, implying its crucial role in pathogenesis. Moreover, the tropism of LukED for murine phagocytes highlights the utility of murine models to study LukED pathobiology, including development and testing of strategies to inhibit toxin activity and control bacterial infection.
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Affiliation(s)
- Francis Alonzo
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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Alonzo F, Xayarath B, Whisstock JC, Freitag NE. Functional analysis of the Listeria monocytogenes secretion chaperone PrsA2 and its multiple contributions to bacterial virulence. Mol Microbiol 2011; 80:1530-48. [PMID: 21545417 DOI: 10.1111/j.1365-2958.2011.07665.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
As an organism that has evolved to live in environments ranging from soil to the cytosol of mammalian cells, Listeria monocytogenes must regulate the secretion and activity of protein products that promote survival within these habitats. The post-translocation chaperone PrsA2 has been adapted to assist in the folding and activity of L. monocytogenes secreted proteins required for bacterial replication within host cells. Here we present the first structure/function investigation of the contributions of PrsA2 to protein secretion and activity as well as to bacterial virulence. Domain swap experiments with the closely related L. monocytogenes PrsA1 protein combined with targeted mutagenesis indicate distinct functional roles for the PrsA2 peptidyl-prolyl isomerase (PPIase) and the N- and C-terminal domains in pathogenesis. In contrast to other PrsA-like proteins described thus far in the literature, an absolute in vivo requirement for PrsA2 PPIase activity is evident in mouse infection models. This work illustrates the diversity of function associated with L. monocytogenes PrsA2 that serves to promote bacterial life within the infected host.
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Affiliation(s)
- Francis Alonzo
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL, USA
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Abstract
Cardiac infections caused by the foodborne bacterium Listeria monocytogenes represent a significant but poorly studied facet of disease. It is not known whether L. monocytogenes cardiac infections stem solely from host susceptibility, or whether bacterial isolates exist that exhibit a tropism for cardiac tissue. Here we examine the cardio-invasive capacity of a recent L. monocytogenes cardiac case strain (07PF0776) as well as nine additional outbreak and clinical isolates. Mice infected with the cardiac isolate 07PF0776 had 10-fold more bacteria recovered from heart tissue than those infected with L. monocytogenes strain 10403S, a well-characterized clinical isolate originally obtained from a human skin lesion. Additional L. monocytogenes isolates exhibited varied capacities to colonize the hearts of mice; however, those with the highest efficiency of mouse cardiac invasion also demonstrated the highest levels of bacterial invasion in cultured myoblast cells. Our findings strongly suggest that subpopulations of L. monocytogenes strains have acquired an enhanced ability to target and invade the myocardium.
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Affiliation(s)
- Francis Alonzo
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL, USA
| | - Linda D Bobo
- Adult Infectious Diseases, Washington University School of Medicine, St Louis, MO, USA
| | - Daniel J Skiest
- Division of Infectious Diseases, Baystate Medical Center - Tufts University School of Medicine, Springfield, MA, USA
| | - Nancy E Freitag
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL, USA
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Bermond F, Bruyere K, Alonzo F, Stagnara A, Poirot D, David T. Preliminary results of the thoracic and abdominal compliance in children on different ventilatory programs. Comput Methods Biomech Biomed Engin 2009. [DOI: 10.1080/10255840903065167] [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: 10/20/2022]
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Alonzo F, Hertel-Aas T, Gilek M, Gilbin R, Oughton DH, Garnier-Laplace J. Modelling the propagation of effects of chronic exposure to ionising radiation from individuals to populations. J Environ Radioact 2008; 99:1464-1473. [PMID: 18314232 DOI: 10.1016/j.jenvrad.2007.11.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 11/12/2007] [Accepted: 11/29/2007] [Indexed: 05/26/2023]
Abstract
This study evaluated the potential effect of ionising radiation on population growth using simple population models and parameter values derived from chronic exposure experiments in two invertebrate species with contrasting life-history strategies. In the earthworm Eisenia fetida, models predicted increasing delay in population growth with increasing gamma dose rate (up to 0.6 generation times at 11 mGy h(-1)). Population extinction was predicted at 43 mGy h(-1). In the microcrustacean Daphnia magna, models predicted increasing delay in population growth with increasing alpha dose rate (up to 0.8 generation times at 15.0 mGy h(-1)), only after two successive generations were exposed. The study examined population effects of changes in different individual endpoints (including survival, number of offspring produced and time to first reproduction). Models showed that the two species did not respond equally to equivalent levels of change, the fast growing daphnids being more susceptible to reduction in fecundity or delay in reproduction than the slow growing earthworms. This suggested that susceptibility of a population to ionising radiation cannot be considered independent of the species' life history.
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Affiliation(s)
- F Alonzo
- Laboratory of Environmental Modelling, DEI/SECRE/LME, Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache, Building 159, BP3, 13115 St-Paul-lez-Durance Cedex, France.
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Garnier-Laplace J, Copplestone D, Gilbin R, Alonzo F, Ciffroy P, Gilek M, Agüero A, Björk M, Oughton DH, Jaworska A, Larsson CM, Hingston JL. Issues and practices in the use of effects data from FREDERICA in the ERICA Integrated Approach. J Environ Radioact 2008; 99:1474-1483. [PMID: 18550231 DOI: 10.1016/j.jenvrad.2008.04.012] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Revised: 02/18/2008] [Accepted: 04/10/2008] [Indexed: 05/26/2023]
Abstract
The ERICA Integrated Approach requires that a risk assessment screening dose rate is defined for the risk characterisation within Tiers 1 and 2. At Tier 3, no numerical screening dose rate is used, and the risk characterisation is driven by methods that can evaluate the possible effects of ionising radiation on reproduction, mortality and morbidity. Species sensitivity distribution has been used to derive the ERICA risk assessment predicted no-effect dose rate (PNEDR). The method used was based on the mathematical processing of data from FRED (FASSET radiation effects database merged with the EPIC database to form FREDERICA) and resulted in a PNEDR of 10 microGy/h. This rate was assumed to ascribe sufficient protection of all ecosystems from detrimental effects on structure and function under chronic exposure. The value was weighed against a number of points of comparison: (i) PNEDR values obtained by application of the safety factor method, (ii) background levels, (iii) dose rates triggering effects on radioactively contaminated sites and (iv) former guidelines from literature reviews. In Tier 3, the effects analysis must be driven by the problem formulation and is thus highly case specific. Instead of specific recommendations on numeric values, guidance on the sorts of methods that may be applied for refined effect analysis is provided and illustrated.
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Affiliation(s)
- J Garnier-Laplace
- Institute of Radioprotection and Nuclear Safety (IRSN), DEI/SECRE, Laboratory of Radioecology and Ecotoxicology, Cadarache Building 186, BP3, 13115 St-Paul-lez-Durance Cedex, France.
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Alonzo F, Gilbin R, Zeman FA, Garnier-Laplace J. Increased effects of internal alpha irradiation in Daphnia magna after chronic exposure over three successive generations. Aquat Toxicol 2008; 87:146-156. [PMID: 18325610 DOI: 10.1016/j.aquatox.2008.01.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 01/18/2008] [Accepted: 01/21/2008] [Indexed: 05/26/2023]
Abstract
A 70-day experiment was performed with Daphnia magna exposed to waterborne Am-241 on a range of concentrations (from 0.4 to 40 Bq ml(-1)) in order to test chronic effects of internal alpha irradiation on respiration, somatic growth and reproduction over three successive generations. Changes in Am-241 concentrations were followed in the water and in daphnid tissues, eggs and cuticles. Corresponding average dose rates of 0.3, 1.5 and 15 mGy h(-1) were estimated. This study confirmed that oxygen consumption increased significantly in the first generation (F0) after 6 days of exposure to a dose rate >or=1.5 mGy h(-1). Consequences were limited to a reduction in body length (5%) and dry mass of females (16%) and eggs (8%) after 23 days of exposure, while mortality and fecundity remained unaffected. New cohorts were started with neonates of broods 1 and 5, to examine potential consequences of the reduced mass of offspring for subsequent exposed generations. Results strongly contrasted with those observed in F0. At the highest dose rate, an early mortality of 38-90% affected juveniles while survivors showed delayed reproduction and reduced fecundity in F1 and F2. At 0.3 and 1.5 mGy h(-1), mortality ranged from 31 to 38% of daphnids depending on dose rate, but was observed only in generation F1 started with neonates of the brood 1. Reproduction was affected through a reduction in the proportion of breeding females, occurring in the first offspring generation at 1.5 mGy h(-1) (to 62% of total daphnids) and in the second generation at 0.3 mGy h(-1) (to 69% of total daphnids). Oxygen consumption remained significantly higher at dose rates >or=0.3 mGy h(-1) than in the control in almost every generation. Body size and mass continued decreasing in relation to dose rate, with a significant reduction in mass ranging from 15% at 0.3 mGy h(-1) to 27% at 15 mGy h(-1) in the second offspring generation.
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Affiliation(s)
- F Alonzo
- Laboratory of Environmental Modelling, DEI/SECRE/LME, Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache, Building 159, BP3, 13115 St-Paul-lez-Durance Cedex, France.
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40
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Alonzo F, Gilbin R, Bourrachot S, Floriani M, Morello M, Garnier-Laplace J. Effects of chronic internal alpha irradiation on physiology, growth and reproductive success of Daphnia magna. Aquat Toxicol 2006; 80:228-36. [PMID: 17049381 DOI: 10.1016/j.aquatox.2006.09.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Revised: 08/30/2006] [Accepted: 09/01/2006] [Indexed: 05/12/2023]
Abstract
Daphnids were chronically exposed to waterborne Am-241, an alpha-emitting radionuclide, ranging in concentration from 0.4 to 40 Bq ml(-1). Am-241 amounts were monitored in the medium, daphnid tissues and cuticles. Corresponding average dose rates of 0.02, 0.11 and 0.99 mGy h(-1) were calculated for whole organisms with internal alpha-radiation contributing 99% of total dose rates. Effects of internal alpha irradiation on respiration and ingestion rates, adult, egg and neonate individual dry masses, fecundity and larval resistance to starvation were examined in 23-day experiments. Daphnids showed increased respiratory demand after 23 days at the highest dose rate, suggesting increased metabolic cost of maintenance due to coping with alpha radiological stress. Although no effect was detected on ingestion rates between contaminated and control daphnids, exposure to dose rates of 0.11 mGy h(-1) or higher, resulted in a significant 15% reduction in body mass. Fecundity remained unchanged over the 23-day period, but individual masses of eggs and neonates were significantly smaller compared to the control. This suggested that increased metabolic expenditure in chronically alpha-radiated daphnids came at the expense of their energy investment per offspring. As a consequence, neonates showed significantly reduced resistance to starvation at every dose rate compared to the control. Our observations are discussed in comparison with literature results reported for cadmium, a chemical toxicant which affects feeding activity and strongly reduces individual energy uptake.
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Affiliation(s)
- F Alonzo
- Laboratory of Radioecology and Ecotoxicology, DEI/SECRE/LRE, Institute of Radioprotection and Nuclear Safety (IRSN), Cadarache Building 186, BP3, 13115 St-Paul-lez-Durance Cedex, France.
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Bermond F, Bergeau J, Alonzo F, Goubel C, Bruyère K, Joffrin P, Cossalter B, Verriest JP. Enhanced method and tools for child thoracic and abdominal compliance assessment by clinical treatments observation. J Biomech 2006. [DOI: 10.1016/s0021-9290(06)83528-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Alonzo F, Bermond F, Beillas P. Child abdominal injuries in car restraint systems—An intra-abdominal pressure sensor for the Q-dummy family and proposed viscous injury criterion based on detailed accident analysis and their reconstructions. J Biomech 2006. [DOI: 10.1016/s0021-9290(06)83545-1] [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: 10/24/2022]
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Distasi C, Lovisolo D, Alonzo F, Tolosano E, Fasolo A. Role of extracellular matrix molecules in the development of the sodium current in quail mesencephalic neural crest cells. Experientia 1992; 48:859-64. [PMID: 1327860 DOI: 10.1007/bf02118419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- C Distasi
- Università di Torino, Dipartimento di Biologia Animale, Italy
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Lovisolo D, Bonelli G, Baccino FM, Peres A, Alonzo F, Munaron L. Two currents activated by epidermal growth factor in EGFR-T17 fibroblasts. Biochim Biophys Acta 1992; 1104:73-82. [PMID: 1550855 DOI: 10.1016/0005-2736(92)90133-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Application of 10 nM Epidermal Growth Factor (EGF) to single EGFR-T17 fibroblasts induced a marked hyperpolarization that could last for tens of minutes; in many cases the first transient was followed by a series of oscillations of the membrane potential. The outward current responsible for the hyperpolarizing response could be recorded simultaneously to an increase in the intracellular calcium concentration, as measured with the fluorescent indicator fura-2. The conductance was nearly linear in the voltage range from -100 to +50 mV. While the EGF-induced current had many characteristics of a K+ current and was strongly reduced by 50 nM charybdotoxin (ChTx), its reversal potential was apparently more negative than the potassium equilibrium potential (VK). The application of 2 microM ouabain prior to EGF stimulation produced responses that were similar to those obtained without ouabain; however, under these conditions the EGF-induced current showed a reversal potential of -96.6 +/- 3.2 mV, very close to VK. Simultaneous application of both 2 microM ouabain and 50 nM ChTx completely abolished the response. It can be concluded that the response to EGF stimulation in EGFR-T17 cells consists of two components: the first is a current carried through Ca(2+)-activated K+ channels; the second is due to the acceleration of the operation of the Na+/K(+)-ATPase.
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Affiliation(s)
- D Lovisolo
- Dipartimento di Biologia Animale, Università di Torino, Italy
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Alonzo F, Fenoggio M, Cocola M. [Rigid osteosynthesis as an immediate and differed emergency in the geriatric age group]. G Gerontol 1971; 19:902-10. [PMID: 5143554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Alonzo F. [Osteosynthesis as an emergency surgical problem in fractures of the proximal end of the femur]. Minerva Ortop 1971; 22:57-9. [PMID: 5579738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Alonzo F, Magrini G. [Our experience in the treatment of fractures of the tibial plate]. Minerva Ortop 1967; 18:415-7. [PMID: 5607010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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