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Thai VC, Stubbs KA, Sarkar-Tyson M, Kahler CM. Phosphoethanolamine Transferases as Drug Discovery Targets for Therapeutic Treatment of Multi-Drug Resistant Pathogenic Gram-Negative Bacteria. Antibiotics (Basel) 2023; 12:1382. [PMID: 37760679 PMCID: PMC10525099 DOI: 10.3390/antibiotics12091382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 08/25/2023] [Accepted: 08/26/2023] [Indexed: 09/29/2023] Open
Abstract
Antibiotic resistance caused by multidrug-resistant (MDR) bacteria is a major challenge to global public health. Polymyxins are increasingly being used as last-in-line antibiotics to treat MDR Gram-negative bacterial infections, but resistance development renders them ineffective for empirical therapy. The main mechanism that bacteria use to defend against polymyxins is to modify the lipid A headgroups of the outer membrane by adding phosphoethanolamine (PEA) moieties. In addition to lipid A modifying PEA transferases, Gram-negative bacteria possess PEA transferases that decorate proteins and glycans. This review provides a comprehensive overview of the function, structure, and mechanism of action of PEA transferases identified in pathogenic Gram-negative bacteria. It also summarizes the current drug development progress targeting this enzyme family, which could reverse antibiotic resistance to polymyxins to restore their utility in empiric therapy.
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Affiliation(s)
- Van C. Thai
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (V.C.T.); (M.S.-T.)
| | - Keith A. Stubbs
- School of Molecular Sciences, University of Western Australia, Crawley, WA 6009, Australia;
| | - Mitali Sarkar-Tyson
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (V.C.T.); (M.S.-T.)
| | - Charlene M. Kahler
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA 6009, Australia; (V.C.T.); (M.S.-T.)
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2
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Girgis MM, Christodoulides M. Vertebrate and Invertebrate Animal and New In Vitro Models for Studying Neisseria Biology. Pathogens 2023; 12:782. [PMID: 37375472 DOI: 10.3390/pathogens12060782] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/03/2023] [Accepted: 05/18/2023] [Indexed: 06/29/2023] Open
Abstract
The history of Neisseria research has involved the use of a wide variety of vertebrate and invertebrate animal models, from insects to humans. In this review, we itemise these models and describe how they have made significant contributions to understanding the pathophysiology of Neisseria infections and to the development and testing of vaccines and antimicrobials. We also look ahead, briefly, to their potential replacement by complex in vitro cellular models.
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Affiliation(s)
- Michael M Girgis
- Neisseria Research Group, Molecular Microbiology, School of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
- Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt
| | - Myron Christodoulides
- Neisseria Research Group, Molecular Microbiology, School of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO16 6YD, UK
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3
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Mullally C, Stubbs KA, Thai VC, Anandan A, Bartley S, Scanlon MJ, Jarvis GA, John CM, Lim KYL, Sullivan CM, Sarkar-Tyson M, Vrielink A, Kahler CM. Novel small molecules that increase the susceptibility of Neisseria gonorrhoeae to cationic antimicrobial peptides by inhibiting lipid A phosphoethanolamine transferase. J Antimicrob Chemother 2022; 77:2441-2447. [PMID: 35770844 PMCID: PMC9410672 DOI: 10.1093/jac/dkac204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 05/19/2022] [Indexed: 11/14/2022] Open
Abstract
Objectives Neisseria gonorrhoeae is an exclusively human pathogen that commonly infects the urogenital tract resulting in gonorrhoea. Empirical treatment of gonorrhoea with antibiotics has led to multidrug resistance and the need for new therapeutics. Inactivation of lipooligosaccharide phosphoethanolamine transferase A (EptA), which attaches phosphoethanolamine to lipid A, results in attenuation of the pathogen in infection models. Small molecules that inhibit EptA are predicted to enhance natural clearance of gonococci via the human innate immune response. Methods A library of small-fragment compounds was tested for the ability to enhance susceptibility of the reference strain N. gonorrhoeae FA1090 to polymyxin B. The effect of these compounds on lipid A synthesis and viability in models of infection were tested. Results Three compounds, 135, 136 and 137, enhanced susceptibility of strain FA1090 to polymyxin B by 4-fold. Pre-treatment of bacterial cells with all three compounds resulted in enhanced killing by macrophages. Only lipid A from bacterial cells exposed to compound 137 showed a 17% reduction in the level of decoration of lipid A with phosphoethanolamine by MALDI-TOF MS analysis and reduced stimulation of cytokine responses in THP-1 cells. Binding of 137 occurred with higher affinity to purified EptA than the starting material, as determined by 1D saturation transfer difference NMR. Treatment of eight MDR strains with 137 increased susceptibility to polymyxin B in all cases. Conclusions Small molecules have been designed that bind to EptA, inhibit addition of phosphoethanolamine to lipid A and can sensitize N. gonorrhoeae to killing by macrophages.
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Affiliation(s)
- Christopher Mullally
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Science, University of Western Australia, Perth, Australia
| | - Keith A Stubbs
- School of Molecular Sciences, University of Western Australia, Perth, Australia
| | - Van C Thai
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Science, University of Western Australia, Perth, Australia
| | - Anandhi Anandan
- School of Molecular Sciences, University of Western Australia, Perth, Australia
| | - Stephanie Bartley
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Science, University of Western Australia, Perth, Australia
| | - Martin J Scanlon
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Australia
| | - Gary A Jarvis
- Center for Immunochemistry, Veterans Affairs Medical Center, San Francisco, USA.,Department of Laboratory Medicine, University of California, San Francisco, USA
| | - Constance M John
- Center for Immunochemistry, Veterans Affairs Medical Center, San Francisco, USA.,Department of Laboratory Medicine, University of California, San Francisco, USA
| | - Katherine Y L Lim
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Science, University of Western Australia, Perth, Australia
| | - Courtney M Sullivan
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Science, University of Western Australia, Perth, Australia
| | - Mitali Sarkar-Tyson
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Science, University of Western Australia, Perth, Australia
| | - Alice Vrielink
- School of Molecular Sciences, University of Western Australia, Perth, Australia
| | - Charlene M Kahler
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Science, University of Western Australia, Perth, Australia.,Telethon Kids Institute, Perth Children's Hospital, Perth, Australia
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4
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Zhang S, Zhang Y, Gan L, Wei F, Chai B, A Aljaafreh AAH, Liu X, Duan X, Jiang J, Wang X, He M, Huang X, Cai H, Chen T, Chen H. Progesterone Suppresses Neisseria gonorrhoeae-Induced Inflammation Through Inhibition of NLRP3 Inflammasome Pathway in THP-1 Cells and Murine Models. Front Microbiol 2021; 12:570093. [PMID: 33633700 PMCID: PMC7900005 DOI: 10.3389/fmicb.2021.570093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 01/15/2021] [Indexed: 01/01/2023] Open
Abstract
Asymptomatic/subclinical gonococcal infections in females continue to be prevalent within the general population, thus emerging as a global health problem. However, the reasons for these clinical manifestations are unknown. Our group had previously found out that in females, asymptomatic gonococcal infections correlate with higher serum progesterone (P4) levels and lower IL-1β levels in cervical secretions. We used murine infection model and THP-1 cells to determine whether P4 exerts anti-inflammatory effects on gonococcal infections. In the murine infection model, P4 (1 mg/day) inhibited the inflammatory effects induced by gonococcal infections which led to decreased neutrophil infiltration, reduced polymorphonuclear neutrophils (PMNs) numbers, IL-1β, TNF-α, and IL-6 levels in vaginal secretions. In addition, P4 down-regulated the mRNA and protein levels of NLRP3, associated with lower mRNA levels of pro-IL-1β, repressed caspase-1 activity in genital tissues and THP-1 cells. Moreover, P4 suppressed the phosphorylation levels of NF-κB and attenuated Neisseria gonorrhoeae (N. gonorrhoeae, gonococci or GC)-induced ROS generation. This is consistent with the two signals required for activation of the NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) inflammasome. In conclusion, our result shows that P4 suppresses the gonococci induced-inflammation, especially through the NLRP3 inflammasome pathway, and partially explains the pathogenesis of asymptomatic GC infection in women.
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Affiliation(s)
- Song Zhang
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yingmiao Zhang
- Department of Clinical Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, Wuhan, China.,Department of Clinical Laboratory, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Tchnology, Wuhan, China
| | - Lu Gan
- Department of Dermatology, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Fen Wei
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Bao Chai
- Department of Dermatology, The 6th Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen, China.,Department of Dermatology, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, China
| | - Amaneh Abdel Hafez A Aljaafreh
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xinxin Liu
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoru Duan
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jian Jiang
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xin Wang
- Department of Dermatology, Affiliated Hospital of Nantong University, Nantong, China
| | - Mengwen He
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xian Huang
- Department of Dermatology, The 6th Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen, China
| | - Huahua Cai
- Department of Clinical Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, Wuhan, China
| | - Tie Chen
- Department of Clinical Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Sciences and Technology, Wuhan, China
| | - Hongxiang Chen
- Department of Dermatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Department of Dermatology, The 6th Affiliated Hospital of Shenzhen University Health Science Center, Shenzhen, China.,Department of Dermatology, Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, China
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5
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John CM, Phillips NJ, Jarvis GA. Predominant phosphorylation patterns in Neisseria meningitidis lipid A determined by top-down MS/MS. J Lipid Res 2020; 61:1437-1449. [PMID: 32839198 DOI: 10.1194/jlr.ra120001014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Among the virulence factors in Neisseria infections, a major inducer of inflammatory cytokines is the lipooligosaccharide (LOS). The activation of NF-κB via extracellular binding of LOS or lipopolysaccharide (LPS) to the toll-like receptor 4 and its coreceptor, MD-2, results in production of pro-inflammatory cytokines that initiate adaptive immune responses. LOS can also be absorbed by cells and activate intracellular inflammasomes, causing the release of inflammatory cytokines and pyroptosis. Studies of LOS and LPS have shown that their inflammatory potential is highly dependent on lipid A phosphorylation and acylation, but little is known on the location and pattern of these posttranslational modifications. Herein, we report on the localization of phosphoryl groups on phosphorylated meningococcal lipid A, which has two to three phosphate and zero to two phosphoethanolamine substituents. Intact LOS with symmetrical hexa-acylated and asymmetrical penta-acylated lipid A moieties was subjected to high-resolution ion mobility spectrometry MALDI-TOF MS. LOS molecular ions readily underwent in-source decay to give fragments of the oligosaccharide and lipid A formed by cleavage of the ketosidic linkage, which enabled performing MS/MS (pseudo-MS3). The resulting spectra revealed several patterns of phosphoryl substitution on lipid A, with certain species predominating. The extent of phosphoryl substitution, particularly phosphoethanolaminylation, on the 4'-hydroxyl was greater than that on the 1-hydroxyl. The heretofore unrecognized phosphorylation patterns of lipid A of meningococcal LOS that we detected are likely determinants of both pathogenicity and the ability of the bacteria to evade the innate immune system.
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Affiliation(s)
- Constance M John
- Center for Immunochemistry, Veterans Affairs Medical Center, San Francisco, CA, USA.,Department of Laboratory Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Nancy J Phillips
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA, USA
| | - Gary A Jarvis
- Center for Immunochemistry, Veterans Affairs Medical Center, San Francisco, CA, USA .,Department of Laboratory Medicine, University of California, San Francisco, San Francisco, CA, USA
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Samantha A, Vrielink A. Lipid A Phosphoethanolamine Transferase: Regulation, Structure and Immune Response. J Mol Biol 2020; 432:5184-5196. [PMID: 32353363 DOI: 10.1016/j.jmb.2020.04.022] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 04/17/2020] [Accepted: 04/22/2020] [Indexed: 01/23/2023]
Abstract
A wide variety of antibiotics are targeted to the bacterial membrane due to its unique arrangement and composition relative to the host mammalian membranes. By modification of their membranes, some gram-negative pathogens resist the action of antibiotics. Lipid A phosphoethanolamine transferase (EptA) is an intramembrane enzyme that modifies the lipid A portion of lipopolysaccharide/lipooligosaccharide by the addition of phosphoethanolamine. This modification reduces the overall net-negative charge of the outer membrane of some gram-negative bacteria, conferring resistance to polymyxin. This resistance mechanism has resulted in a global public health issue due to the increased use of polymyxin as last-resort antibiotic treatments against multi-drug-resistant pathogens. Studies show that, without EptA, pathogenic bacteria become more sensitive to polymyxin and to clearance by the host immune system, suggesting the importance of this target enzyme for the development of novel therapeutic agents. In this review, EptA will be discussed comprehensively. Specifically, this review will cover the regulation of eptA expression by the two component systems PmrA/PmrB and PhoP/PhoQ, the site of modification on lipid A, the structure and catalytic mechanism of EptA in comparison to MCR-1 and Escherichia coli alkaline phosphatase, and the host immune system's response to lipid A modification by EptA. The overarching aim of this review is to provide a comprehensive overview of polymyxin resistance mediated by EptA.
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Affiliation(s)
- Ariela Samantha
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia
| | - Alice Vrielink
- School of Molecular Sciences, University of Western Australia, 35 Stirling Highway, Perth, WA 6009, Australia.
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7
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Identification of a Neisseria gonorrhoeae Histone Deacetylase: Epigenetic Impact on Host Gene Expression. Pathogens 2020; 9:pathogens9020132. [PMID: 32085531 PMCID: PMC7168274 DOI: 10.3390/pathogens9020132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/11/2020] [Accepted: 02/14/2020] [Indexed: 12/19/2022] Open
Abstract
Epigenetic reprogramming in macrophages is termed trained innate immunity, which regulates immune tolerance and limits tissue damage during infection. Neisseria gonorrhoeae is a strict human pathogen that causes the sexually transmitted infection termed gonorrhea. Here, we report that this pathogen harbors a gene that encodes a histone deacetylase-like enzyme (Gc-HDAC) that shares high 3D-homology to human HDAC1, HDAC2 and HDAC8. A Gc-HDAC null mutant was constructed to determine the biologic significance of this gene. The results showed that WT gonococci reduced the expression of host defense peptides LL-37, HBD-1 and SLPI in macrophages when compared to its Gc-HDAC-deficient isogenic strain. The enrichment of epigenetic marks in histone tails control gene expression and are known to change during bacterial infections. To investigate whether gonococci exert epigenetic modifications on host chromatin, the enrichment of acetylated lysine 9 in histone 3 (H3K9ac) was investigated using the TLR-focused ChIP array system. The data showed that infection with WT gonococci led to higher H3K9ac enrichment at the promoters of pro-inflammatory mediators' genes, many TLRs, adaptor proteins and transcription factors, suggesting gene activation when compared to infection with the Gc-HDAC-deficient mutant. Taken together, the data suggest that gonococci can exert epigenetic modifications on host cells to modulate certain macrophage defense genes, leading to a maladaptive state of trained immunity.
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8
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Vincent LR, Jerse AE. Biological feasibility and importance of a gonorrhea vaccine for global public health. Vaccine 2019; 37:7419-7426. [PMID: 29680200 PMCID: PMC6892272 DOI: 10.1016/j.vaccine.2018.02.081] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 02/05/2018] [Accepted: 02/19/2018] [Indexed: 02/06/2023]
Abstract
There is a growing public health interest in controlling sexually transmitted infections (STIs) through vaccination due to increasing recognition of the global disease burden of STIs and the role of STIs in women's reproductive health, adverse pregnancy outcomes, and the health and well-being of neonates. Neisseria gonorrhoeae has historically challenged vaccine development through the expression of phase and antigenically variable surface molecules and its capacity to cause repeated infections without inducing protective immunity. An estimated 78 million new N. gonorrhoeae infections occur annually and the greatest disease burden is carried by low- and middle-income countries (LMIC). Current control measures are clearly inadequate and threatened by the rapid emergence of antibiotic resistance. The gonococcus now holds the status of "super-bug" as there is currently no single reliable monotherapy for empirical treatment of gonorrhea. The problem of antibiotic resistance has elevated treatment costs and necessitated the establishment of large surveillance programs to track the spread of resistant strains. Here we review the need for a gonorrhea vaccine with respect to global disease burden and related socioeconomic and treatment costs, with an emphasis on the impact of gonorrhea on women and newborns. We also highlight the challenge of estimating the impact of a gonorrhea vaccine due to the need for more data on the burden of gonococcal pelvic inflammatory disease and related sequelae and of gonorrhea-associated adverse pregnancy outcomes and the problem of empirical diagnosis and treatment of STIs in LMIC. There is also a lack of clinical and basic science research in the area of gonococcal/chlamydia coinfection, which occurs in a high percentage of individuals with gonorrhea and should be considered when testing the efficacy of gonorrhea vaccines. Finally, we review recent research that suggests a gonorrhea vaccine is feasible and discuss challenges and research gaps in gonorrhea vaccine development.
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Affiliation(s)
- Leah R Vincent
- National Institute of Allergy and Infectious Diseases, 5601 Fishers Lane, Rockville, MD 20852, United States.
| | - Ann E Jerse
- Department of Microbiology and Immunology F. Edward Herbert School of Medicine, Uniformed Services University, 4301 Jones Bridge Road, Bethesda, MD 20854, United States.
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9
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Komazin G, Maybin M, Woodard RW, Scior T, Schwudke D, Schombel U, Gisch N, Mamat U, Meredith TC. Substrate structure-activity relationship reveals a limited lipopolysaccharide chemotype range for intestinal alkaline phosphatase. J Biol Chem 2019; 294:19405-19423. [PMID: 31704704 DOI: 10.1074/jbc.ra119.010836] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 10/31/2019] [Indexed: 12/21/2022] Open
Abstract
Lipopolysaccharide (LPS) from the Gram-negative bacterial outer membrane potently activates the human innate immune system. LPS is recognized by the Toll-like receptor 4/myeloid differentiation factor-2 (TLR4/MD2) complex, leading to the release of pro-inflammatory cytokines. Alkaline phosphatase (AP) is currently being investigated as an anti-inflammatory agent for detoxifying LPS through dephosphorylating lipid A, thus providing a potential treatment for managing both acute (sepsis) and chronic (metabolic endotoxemia) pathologies wherein aberrant TLR4/MD2 activation has been implicated. Endogenous LPS preparations are chemically heterogeneous, and little is known regarding the LPS chemotype substrate range of AP. Here, we investigated the activity of AP on a panel of structurally defined LPS chemotypes isolated from Escherichia coli and demonstrate that calf intestinal AP (cIAP) has only minimal activity against unmodified enteric LPS chemotypes. Pi was only released from a subset of LPS chemotypes harboring spontaneously labile phosphoethanolamine (PEtN) modifications connected through phosphoanhydride bonds. We demonstrate that the spontaneously hydrolyzed O-phosphorylethanolamine is the actual substrate for AP. We found that the 1- and 4'-lipid A phosphate groups critical in TLR4/MD2 signaling become susceptible to hydrolysis only after de-O-acylation of ester linked primary acyl chains on lipid A. Furthermore, PEtN modifications on lipid A specifically enhanced hTLR4 agonist activity of underacylated LPS preparations. Computational binding models are proposed to explain the limitation of AP substrate specificity imposed by the acylation state of lipid A, and the mechanism of PEtN in enhancing hTLR4/MD2 signaling.
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Affiliation(s)
- Gloria Komazin
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Michael Maybin
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Ronald W Woodard
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Thomas Scior
- Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Puebla 72000, Mexico
| | - Dominik Schwudke
- Bioanalytical Chemistry, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Ursula Schombel
- Bioanalytical Chemistry, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Nicolas Gisch
- Bioanalytical Chemistry, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Uwe Mamat
- Cellular Microbiology, Priority Research Area Infections, Research Center Borstel, Leibniz Lung Center, 23845 Borstel, Germany
| | - Timothy C Meredith
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
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10
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Pharmacokinetic Data Are Predictive of In Vivo Efficacy for Cefixime and Ceftriaxone against Susceptible and Resistant Neisseria gonorrhoeae Strains in the Gonorrhea Mouse Model. Antimicrob Agents Chemother 2019; 63:AAC.01644-18. [PMID: 30642924 DOI: 10.1128/aac.01644-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 12/18/2018] [Indexed: 01/10/2023] Open
Abstract
There is a pressing need for drug development for gonorrhea. Here we describe a pharmacokinetic (PK)/pharmacodynamic (PD) analysis of extended-spectrum cephalosporins (ESC) against drug-susceptible and drug-resistant gonococcal strains in a murine genital tract infection model. The PK determined in uninfected mice displayed a clear dose-response in plasma levels following single doses of ceftriaxone (CRO) (intraperitoneal) or cefixime (CFM) (oral). The observed doses required for efficacy against ESC-susceptible (ESCs) strain FA1090 were 5 mg/kg of body weight (CRO) and 12 mg/kg (CFM); these doses had estimated therapeutic times (the time that the free drug concentration remains above the MIC [fT MIC]) of 24 h and 37 h, respectively. No single dose of CRO or CFM was effective against ESC-resistant (ESCr) strain H041. However, fractionation (three times a day every 8 h [TIDq8h]) of a 120-mg/kg dose of CRO resulted in estimated therapeutic times in the range of 23 h and cleared H041 infection in a majority (90%) of mice, comparable to the findings for gentamicin. In contrast, multiple CFM doses of 120 or 300 mg/kg administered TIDq8h cleared infection in ≤50% of mice, with the therapeutic times estimated from single-dose PK data being 13 and 27 h, respectively. This study reveals a clear relationship between plasma ESC levels and bacterial clearance rates in the gonorrhea mouse model. The PK/PD relationships observed in mice reflected those observed in humans, with in vivo efficacy against an ESCs strain requiring doses that yielded an fT MIC in excess of 20 to 24 h. PK data also accurately predicted the failure of single doses of ESCs against an ESCr strain and were useful in designing effective dosing regimens.
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11
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Schaub RE, Dillard JP. The Pathogenic Neisseria Use a Streamlined Set of Peptidoglycan Degradation Proteins for Peptidoglycan Remodeling, Recycling, and Toxic Fragment Release. Front Microbiol 2019; 10:73. [PMID: 30766523 PMCID: PMC6365954 DOI: 10.3389/fmicb.2019.00073] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 01/15/2019] [Indexed: 12/26/2022] Open
Abstract
Neisseria gonorrhoeae and Neisseria meningitidis release peptidoglycan (PG) fragments from the cell as the bacteria grow. For N. gonorrhoeae these PG fragments are known to cause damage to human Fallopian tube tissue in organ culture that mimics the damage seen in patients with pelvic inflammatory disease. N. meningitidis also releases pro-inflammatory PG fragments, but in smaller amounts than those from N. gonorrhoeae. It is not yet known if PG fragment release contributes to the highly inflammatory conditions of meningitis and meningococcemia caused by N. meningitidis. Examination of the mechanisms of PG degradation and recycling identified proteins required for these processes. In comparison to the model organism E. coli, the pathogenic Neisseria have far fewer PG degradation proteins, and some of these proteins show differences in subcellular localization compared to their E. coli homologs. In particular, some N. gonorrhoeae PG degradation proteins were demonstrated to be in the outer membrane while their homologs in E. coli were found free in the periplasm or in the cytoplasm. The localization of two of these proteins was demonstrated to affect PG fragment release. Another major factor for PG fragment release is the allele of ampG. Gonococcal AmpG was found to be slightly defective compared to related PG fragment permeases, thus leading to increased release of PG. A number of additional PG-related factors affect other virulence functions in Neisseria. Endopeptidases and carboxypeptidases were found to be required for type IV pilus production and resistance to hydrogen peroxide. Also, deacetylation of PG was required for virulence of N. meningitidis as well as normal cell size. Overall, we describe the processes involved in PG degradation and recycling and how certain characteristics of these proteins influence the interactions of these pathogens with their host.
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Affiliation(s)
- Ryan E Schaub
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Joseph P Dillard
- Department of Medical Microbiology and Immunology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
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12
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Neisseria gonorrhoeae PBP3 and PBP4 Facilitate NOD1 Agonist Peptidoglycan Fragment Release and Survival in Stationary Phase. Infect Immun 2019; 87:IAI.00833-18. [PMID: 30510100 DOI: 10.1128/iai.00833-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 11/25/2018] [Indexed: 01/16/2023] Open
Abstract
Neisseria gonorrhoeae releases peptidoglycan fragments during growth, and these molecules induce an inflammatory response in the human host. The proinflammatory molecules include peptidoglycan monomers, peptidoglycan dimers, and free peptides. These molecules can be released by the actions of lytic transglycosylases or an amidase. However, >40% of the gonococcal cell wall is cross-linked, where the peptide stem on one peptidoglycan strand is linked to the peptide stem on a neighboring strand, suggesting that endopeptidases may be required for the release of many peptidoglycan fragments. Therefore, we characterized mutants with individual or combined mutations in genes for the low-molecular-mass penicillin-binding proteins PBP3 and PBP4. Mutations in either dacB, encoding PBP3, or pbpG, encoding PBP4, did not significantly reduce the release of peptidoglycan monomers or free peptides. A mutation in dacB caused the appearance of a larger-sized peptidoglycan monomer, the pentapeptide monomer, and an increased release of peptidoglycan dimers, suggesting the involvement of this enzyme in both the removal of C-terminal d-Ala residues from stem peptides and the cleavage of cross-linked peptidoglycan. Mutation of both dacB and pbpG eliminated the release of tripeptide-containing peptidoglycan fragments concomitantly with the appearance of pentapeptide and dipeptide peptidoglycan fragments and higher-molecular-weight peptidoglycan dimers. In accord with the loss of tripeptide peptidoglycan fragments, the level of human NOD1 activation by the dacB pbpG mutants was significantly lower than that by the wild type. We conclude that PBP3 and PBP4 overlap in function for cross-link cleavage and that these endopeptidases act in the normal release of peptidoglycan fragments during growth.
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El-Rami FE, Zielke RA, Wi T, Sikora AE, Unemo M. Quantitative Proteomics of the 2016 WHO Neisseria gonorrhoeae Reference Strains Surveys Vaccine Candidates and Antimicrobial Resistance Determinants. Mol Cell Proteomics 2019; 18:127-150. [PMID: 30352803 PMCID: PMC6317477 DOI: 10.1074/mcp.ra118.001125] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 10/23/2018] [Indexed: 12/27/2022] Open
Abstract
The sexually transmitted disease gonorrhea (causative agent: Neisseria gonorrhoeae) remains an urgent public health threat globally because of its reproductive health repercussions, high incidence, widespread antimicrobial resistance (AMR), and absence of a vaccine. To mine gonorrhea antigens and enhance our understanding of gonococcal AMR at the proteome level, we performed the first large-scale proteomic profiling of a diverse panel (n = 15) of gonococcal strains, including the 2016 World Health Organization (WHO) reference strains. These strains show all existing AMR profiles - established through phenotypic characterization and reference genome publication - and are intended for quality assurance in laboratory investigations. Herein, these isolates were subjected to subcellular fractionation and labeling with tandem mass tags coupled to mass spectrometry and multi-combinatorial bioinformatics. Our analyses detected 904 and 723 common proteins in cell envelope and cytoplasmic subproteomes, respectively. We identified nine novel gonorrhea vaccine candidates. Expression and conservation of new and previously selected antigens were investigated. In addition, established gonococcal AMR determinants were evaluated for the first time using quantitative proteomics. Six new proteins, WHO_F_00238, WHO_F_00635c, WHO_F_00745, WHO_F_01139, WHO_F_01144c, and WHO_F_01126, were differentially expressed in all strains, suggesting that they represent global proteomic AMR markers, indicate a predisposition toward developing or compensating gonococcal AMR, and/or act as new antimicrobial targets. Finally, phenotypic clustering based on the isolates' defined antibiograms and common differentially expressed proteins yielded seven matching clusters between established and proteome-derived AMR signatures. Together, our investigations provide a reference proteomics data bank for gonococcal vaccine and AMR research endeavors, which enables microbiological, clinical, or epidemiological projects and enhances the utility of the WHO reference strains.
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Affiliation(s)
- Fadi E El-Rami
- From the ‡Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon
| | - Ryszard A Zielke
- From the ‡Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon
| | - Teodora Wi
- §Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland
| | - Aleksandra E Sikora
- From the ‡Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, Oregon;; ¶Vaccine and Gene Therapy Institute, Oregon Health and Science University, Beaverton, Oregon;.
| | - Magnus Unemo
- ‖World Health Organization Collaborating Centre for Gonorrhoea and other Sexually Transmitted Infections, Department of Laboratory Medicine, Clinical Microbiology, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
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Kahler CM, Nawrocki KL, Anandan A, Vrielink A, Shafer WM. Structure-Function Relationships of the Neisserial EptA Enzyme Responsible for Phosphoethanolamine Decoration of Lipid A: Rationale for Drug Targeting. Front Microbiol 2018; 9:1922. [PMID: 30186254 PMCID: PMC6111236 DOI: 10.3389/fmicb.2018.01922] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 07/30/2018] [Indexed: 11/13/2022] Open
Abstract
Bacteria cause disease by two general mechanisms: the action of their toxins on host cells and induction of a pro-inflammatory response that can lead to a deleterious cytokine/chemokine response (e.g., the so-called cytokine storm) often seen in bacteremia/septicemia. These major mechanisms may overlap due to the action of surface structures that can have direct and indirect actions on phagocytic or non-phagocytic cells. In this respect, the lipid A (endotoxin) component of lipopolysaccharide (LPS) possessed by Gram-negative bacteria has been the subject of literally thousands of studies over the past century that clearly identified it as a key virulence factor in endotoxic shock. In addition to its capacity to modulate inflammatory responses, endotoxin can also modulate bacterial susceptibility to host antimicrobials, such as the host defense peptides termed cationic antimicrobial peptides. This review concentrates on the phosphoethanolamine (PEA) decoration of lipid A in the pathogenic species of the genus Neisseria [N. gonorrhoeae and N. meningitidis]. PEA decoration of lipid A is mediated by the enzyme EptA (formerly termed LptA) and promotes resistance to innate defense systems, induces the pro-inflammatory response and can influence the in vivo fitness of bacteria during infection. These important biological properties have driven efforts dealing with the biochemistry and structural biology of EptA that will facilitate the development of potential inhibitors that block PEA addition to lipid A.
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Affiliation(s)
- Charlene M Kahler
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA, Australia.,Perth Children's Hospital, Telethon Kids Institute, Subiaco, WA, Australia
| | - K L Nawrocki
- Department of Microbiology and Immunology, The Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, United States.,Laboratories of Bacterial Pathogenesis, VA Medical Center, Decatur, GA, United States
| | - A Anandan
- School of Molecular Sciences, University of Western Australia, Crawley, WA, Australia
| | - Alice Vrielink
- The Marshall Center for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Crawley, WA, Australia.,School of Molecular Sciences, University of Western Australia, Crawley, WA, Australia
| | - William M Shafer
- Department of Microbiology and Immunology, The Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA, United States.,Laboratories of Bacterial Pathogenesis, VA Medical Center, Decatur, GA, United States
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15
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Palmer A, Criss AK. Gonococcal Defenses against Antimicrobial Activities of Neutrophils. Trends Microbiol 2018; 26:1022-1034. [PMID: 30115561 DOI: 10.1016/j.tim.2018.07.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 07/09/2018] [Accepted: 07/20/2018] [Indexed: 01/05/2023]
Abstract
Neisseria gonorrhoeae initiates a strong local immune response that is characterized by copious recruitment of neutrophils to the site of infection. Neutrophils neutralize microbes by mechanisms that include phagocytosis, extracellular trap formation, production of reactive oxygen species, and the delivery of antimicrobial granular contents. However, neutrophils do not clear infection with N. gonorrhoeae. N. gonorrhoeae not only expresses factors that defend against neutrophil bactericidal components, but it also manipulates neutrophil production and release of these components. In this review, we highlight the numerous approaches used by N. gonorrhoeae to survive exposure to neutrophils both intracellularly and extracellularly. These approaches reflect the exquisite adaptation of N. gonorrhoeae to its obligate human host.
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Affiliation(s)
- Allison Palmer
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908-0734, USA
| | - Alison K Criss
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908-0734, USA.
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16
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Pathogenesis of Neisseria gonorrhoeae in the female reproductive tract: neutrophilic host response, sustained infection, and clinical sequelae. Curr Opin Hematol 2018; 25:13-21. [PMID: 29016383 DOI: 10.1097/moh.0000000000000394] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE OF REVIEW Gonorrhea is a major global health concern, caused by the bacterium Neisseria gonorrhoeae. The main clinical feature of acute gonorrhea is neutrophilic influx that is unable to clear infection. Women of reproductive age are predominantly at risk for serious sequelae of gonorrhea, including pelvic inflammatory disease, ectopic pregnancy, and infertility. This review will highlight how neutrophils are recruited to the female reproductive tract (FRT) in response to N. gonorrhoeae, how N. gonorrhoeae resists killing by neutrophils, and the connection between neutrophilic inflammation and cellular damage. RECENT FINDINGS Epithelial cells and immune cells of the FRT recognize and respond to N. gonorrhoeae lipid A and heptose bisphosphate of lipooligosaccharide, porin, lipoproteins, and peptidoglycan fragments. N. gonorrhoeae skews the resulting immune response toward a neutrophilic, Th17-like response. N. gonorrhoeae has multiple, nonredundant mechanisms to survive inside neutrophils and in neutrophil extracellular traps. Infection that ascends to the upper FRT induces the further release of inflammatory cytokines and matrix metalloproteinases, which cause epithelial damage. SUMMARY N. gonorrhoeae is remarkable in its ability to recruit neutrophils, yet survive in their midst. New models being developed for FRT infection with N. gonorrhoeae will be useful to reveal the mechanisms underlying these observations.
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Rice PA, Shafer WM, Ram S, Jerse AE. Neisseria gonorrhoeae: Drug Resistance, Mouse Models, and Vaccine Development. Annu Rev Microbiol 2018; 71:665-686. [PMID: 28886683 DOI: 10.1146/annurev-micro-090816-093530] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Gonorrhea, an obligate human infection, is on the rise worldwide and gonococcal strains resistant to many antibiotics are emerging. Appropriate antimicrobial treatment and prevention, including effective vaccines, are urgently needed. To guide investigation, an experimental model of genital tract infection has been developed in female mice to study mechanisms by which Neisseria gonorrhoeae evades host-derived antimicrobial factors and to identify protective and immunosuppressive pathways. Refinements of the animal model have also improved its use as a surrogate host of human infection and accelerated the testing of novel therapeutic and prophylactic compounds against gonococcal infection. Reviewed herein are the (a) history of antibiotic usage and resistance against gonorrhea and the consequences of resistance mechanisms that may increase gonococcal fitness and therefore the potential for spread, (b) use of gonococcal infection in the animal model system to study mechanisms of pathogenesis and host defenses, and
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Affiliation(s)
- Peter A Rice
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605-4321; ,
| | - William M Shafer
- Department of Microbiology and Immunology and Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia 30322.,Laboratories of Bacterial Pathogenesis, Veterans Affairs Medical Center, Decatur, Georgia 30033;
| | - Sanjay Ram
- Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605-4321; ,
| | - Ann E Jerse
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University, Bethesda, Maryland 20814-4799;
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18
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Kaszowska M, Wojcik M, Siednienko J, Lugowski C, Lukasiewicz J. Structure-Activity Relationship of Plesiomonas shigelloides Lipid A to the Production of TNF-α, IL-1β, and IL-6 by Human and Murine Macrophages. Front Immunol 2017; 8:1741. [PMID: 29321776 PMCID: PMC5732152 DOI: 10.3389/fimmu.2017.01741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 11/23/2017] [Indexed: 01/27/2023] Open
Abstract
Plesiomonas shigelloides is a Gram-negative bacterium that is associated with diarrheal disease in humans. Lipopolysaccharide (LPS) is the main surface antigen and virulence factor of this bacterium. The lipid A (LA) moiety of LPS is the main region recognized by target cells of immune system. Here, we evaluated the biological activities of P. shigelloides LA for their abilities to induce the productions of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) by human and murine macrophages [THP-1 macrophages and immortalized murine bone marrow-derived macrophages (iBMDM)]. Four native P. shigelloides LA preparations differing in their phosphoethanolamine (PEtn) substitution, length, number, and saturation of fatty acids were compared with Escherichia coli O55 LA. The bisphosphorylated, hexaacylated, and asymmetric forms of the P. shigelloides and E. coli LA molecules had similar activities in human and murine macrophages, indicating that shortening of the acyl chains in P. shigelloides LA had no effect on its in vitro activities. The PEtn decoration also had no impact on the interaction with the toll-like receptor 4/MD-2 receptor complex. The heptaacylated form of P. shigelloides LA decorated with 16:0 exhibited strong effect on proinflammatory activity, significantly decreasing the levels of all tested cytokines in both murine and human macrophages. Our results revealed that despite the presence of shorter acyl chains and an unsaturated acyl residue (16:1), the bisphosphorylated, hexaacylated, and asymmetric forms of P. shigelloides LA represent highly immunostimulatory structures.
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Affiliation(s)
- Marta Kaszowska
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - Marta Wojcik
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - Jakub Siednienko
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - Czeslaw Lugowski
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland.,Department of Biotechnology and Molecular Biology, University of Opole, Opole, Poland
| | - Jolanta Lukasiewicz
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
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19
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Gangaiah D, Raterman EL, Wu H, Fortney KR, Gao H, Liu Y, Jerse AE, Spinola SM. Both MisR (CpxR) and MisS (CpxA) Are Required for Neisseria gonorrhoeae Infection in a Murine Model of Lower Genital Tract Infection. Infect Immun 2017; 85:e00307-17. [PMID: 28652307 PMCID: PMC5563589 DOI: 10.1128/iai.00307-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 06/17/2017] [Indexed: 12/29/2022] Open
Abstract
During infection, Neisseria gonorrhoeae senses and responds to stress; such responses may be modulated by MisRS (NGO0177 and NGO0176), a two-component system that is a homolog of CpxRA. In Escherichia coli, CpxRA senses and responds to envelope stress; CpxA is a sensor kinase/phosphatase for CpxR, a response regulator. When a cpxA mutant is grown in medium containing glucose, CpxR is phosphorylated by acetyl phosphate but cannot be dephosphorylated, resulting in constitutive activation. Kandler and coworkers (J. L. Kandler, C. L. Holley, J. L. Reimche, V. Dhulipala, J. T. Balthazar, A. Muszyński, R. W. Carlson, and W. M. Shafer, Antimicrob Agents Chemother 60:4690-4700, 2016, https://doi.org/10.1128/AAC.00823-16) showed that MisR (CpxR) is required for the maintenance of membrane integrity and resistance to antimicrobial peptides, suggesting a role in gonococcal survival in vivo Here, we evaluated the contributions of MisR and MisS (CpxA) to gonococcal infection in a murine model of cervicovaginal colonization and identified MisR-regulated genes using RNA sequencing (RNA-Seq). The deletion of misR or misS severely reduced the capacity of N. gonorrhoeae to colonize mice or maintain infection over a 7-day period and reduced microbial fitness after exposure to heat shock. Compared to the wild type (WT), the inactivation of misR identified 157 differentially regulated genes, most of which encoded putative envelope proteins. The inactivation of misS identified 17 differentially regulated genes compared to the WT and 139 differentially regulated genes compared to the misR mutant, 111 of which overlapped those differentially expressed in the comparison of the WT versus the misR mutant. These data indicate that an intact MisRS system is required for gonococcal infection of mice. Provided the MisR is constitutively phosphorylated in the misS mutant, the data suggest that controlled but not constitutive activation is required for gonococcal infection in mice.
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Affiliation(s)
- Dharanesh Gangaiah
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Erica L Raterman
- Department of Microbiology and Immunology, F. Edward Herbert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA
| | - Hong Wu
- Department of Microbiology and Immunology, F. Edward Herbert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA
| | - Kate R Fortney
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Hongyu Gao
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Yunlong Liu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ann E Jerse
- Department of Microbiology and Immunology, F. Edward Herbert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA
| | - Stanley M Spinola
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
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20
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Control of gdhR Expression in Neisseria gonorrhoeae via Autoregulation and a Master Repressor (MtrR) of a Drug Efflux Pump Operon. mBio 2017; 8:mBio.00449-17. [PMID: 28400529 PMCID: PMC5388806 DOI: 10.1128/mbio.00449-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The MtrCDE efflux pump of Neisseria gonorrhoeae contributes to gonococcal resistance to a number of antibiotics used previously or currently in treatment of gonorrhea, as well as to host-derived antimicrobials that participate in innate defense. Overexpression of the MtrCDE efflux pump increases gonococcal survival and fitness during experimental lower genital tract infection of female mice. Transcription of mtrCDE can be repressed by the DNA-binding protein MtrR, which also acts as a global regulator of genes involved in important metabolic, physiologic, or regulatory processes. Here, we investigated whether a gene downstream of mtrCDE, previously annotated gdhR in Neisseria meningitidis, is a target for regulation by MtrR. In meningococci, GdhR serves as a regulator of genes involved in glucose catabolism, amino acid transport, and biosynthesis, including gdhA, which encodes an l-glutamate dehydrogenase and is located next to gdhR but is transcriptionally divergent. We report here that in N. gonorrhoeae, expression of gdhR is subject to autoregulation by GdhR and direct repression by MtrR. Importantly, loss of GdhR significantly increased gonococcal fitness compared to a complemented mutant strain during experimental murine infection. Interestingly, loss of GdhR did not influence expression of gdhA, as reported for meningococci. This variance is most likely due to differences in promoter localization and utilization between gonococci and meningococci. We propose that transcriptional control of gonococcal genes through the action of MtrR and GdhR contributes to fitness of N. gonorrhoeae during infection.IMPORTANCE The pathogenic Neisseria species are strict human pathogens that can cause a sexually transmitted infection (N. gonorrhoeae) or meningitis or fulminant septicemia (N. meningitidis). Although they share considerable genetic information, little attention has been directed to comparing transcriptional regulatory systems that modulate expression of their conserved genes. We hypothesized that transcriptional regulatory differences exist between these two pathogens, and we used the gdh locus as a model to test this idea. For this purpose, we studied two conserved genes (gdhR and gdhA) within the locus. Despite general conservation of the gdh locus in gonococci and meningococci, differences exist in noncoding sequences that correspond to promoter elements or potential sites for interacting with DNA-binding proteins, such as GdhR and MtrR. Our results indicate that implications drawn from studying regulation of conserved genes in one pathogen are not necessarily translatable to a genetically related pathogen.
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Bastos P, Trindade F, da Costa J, Ferreira R, Vitorino R. Human Antimicrobial Peptides in Bodily Fluids: Current Knowledge and Therapeutic Perspectives in the Postantibiotic Era. Med Res Rev 2017; 38:101-146. [PMID: 28094448 PMCID: PMC7168463 DOI: 10.1002/med.21435] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 11/04/2016] [Accepted: 11/14/2016] [Indexed: 12/12/2022]
Abstract
Antimicrobial peptides (AMPs) are an integral part of the innate immune defense mechanism of many organisms. Due to the alarming increase of resistance to antimicrobial therapeutics, a growing interest in alternative antimicrobial agents has led to the exploitation of AMPs, both synthetic and isolated from natural sources. Thus, many peptide-based drugs have been the focus of increasing attention by many researchers not only in identifying novel AMPs, but in defining mechanisms of antimicrobial peptide activity as well. Herein, we review the available strategies for the identification of AMPs in human body fluids and their mechanism(s) of action. In addition, an overview of the distribution of AMPs across different human body fluids is provided, as well as its relation with microorganisms and infectious conditions.
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Affiliation(s)
- Paulo Bastos
- Department of Medical Sciences, iBiMED-Institute for Research in Biomedicine, University of Aveiro, Aveiro, Portugal
| | - Fábio Trindade
- Department of Medical Sciences, iBiMED-Institute for Research in Biomedicine, University of Aveiro, Aveiro, Portugal.,Unidade de Investigação Cardiovascular, Departamento de Cirurgia e Fisiologia, Faculdade de Medicina, Universidade do Porto, Porto, Portugal
| | - João da Costa
- Department of Chemistry, CESAM, University of Aveiro, Aveiro, Portugal
| | - Rita Ferreira
- Department of Chemistry, QOPNA, Mass Spectrometry Center, University of Aveiro, Aveiro, Portugal
| | - Rui Vitorino
- Department of Medical Sciences, iBiMED-Institute for Research in Biomedicine, University of Aveiro, Aveiro, Portugal.,Unidade de Investigação Cardiovascular, Departamento de Cirurgia e Fisiologia, Faculdade de Medicina, Universidade do Porto, Porto, Portugal
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22
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The MisR Response Regulator Is Necessary for Intrinsic Cationic Antimicrobial Peptide and Aminoglycoside Resistance in Neisseria gonorrhoeae. Antimicrob Agents Chemother 2016; 60:4690-700. [PMID: 27216061 DOI: 10.1128/aac.00823-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 05/16/2016] [Indexed: 12/24/2022] Open
Abstract
During infection, the sexually transmitted pathogen Neisseria gonorrhoeae (the gonococcus) encounters numerous host-derived antimicrobials, including cationic antimicrobial peptides (CAMPs) produced by epithelial and phagocytic cells. CAMPs have both direct and indirect killing mechanisms and help link the innate and adaptive immune responses during infection. Gonococcal CAMP resistance is likely important for avoidance of host nonoxidative killing systems expressed by polymorphonuclear granulocytes (e.g., neutrophils) and intracellular survival. Previously studied gonococcal CAMP resistance mechanisms include modification of lipid A with phosphoethanolamine by LptA and export of CAMPs by the MtrCDE efflux pump. In the related pathogen Neisseria meningitidis, a two-component regulatory system (2CRS) termed MisR-MisS has been shown to contribute to the capacity of the meningococcus to resist CAMP killing. We report that the gonococcal MisR response regulator but not the MisS sensor kinase is involved in constitutive and inducible CAMP resistance and is also required for intrinsic low-level resistance to aminoglycosides. The 4- to 8-fold increased susceptibility of misR-deficient gonococci to CAMPs and aminoglycosides was independent of phosphoethanolamine decoration of lipid A and the levels of the MtrCDE efflux pump and seemed to correlate with a general increase in membrane permeability. Transcriptional profiling and biochemical studies confirmed that expression of lptA and mtrCDE was not impacted by the loss of MisR. However, several genes encoding proteins involved in membrane integrity and redox control gave evidence of being MisR regulated. We propose that MisR modulates the levels of gonococcal susceptibility to antimicrobials by influencing the expression of genes involved in determining membrane integrity.
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23
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Phosphoethanolamine Modification of Neisseria gonorrhoeae Lipid A Reduces Autophagy Flux in Macrophages. PLoS One 2015; 10:e0144347. [PMID: 26641098 PMCID: PMC4671640 DOI: 10.1371/journal.pone.0144347] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 11/17/2015] [Indexed: 12/14/2022] Open
Abstract
Autophagy, an ancient homeostasis mechanism for macromolecule degradation, performs an important role in host defense by facilitating pathogen elimination. To counteract this host defense strategy, bacterial pathogens have evolved a variety of mechanisms to avoid or otherwise dysregulate autophagy by phagocytic cells so as to enhance their survival during infection. Neisseria gonorrhoeae is a strictly human pathogen that causes the sexually transmitted infection, gonorrhea. Phosphoethanolamine (PEA) addition to the 4' position of the lipid A (PEA-lipid A) moiety of the lipooligosaccharide (LOS) produced by gonococci performs a critical role in this pathogen’s ability to evade innate defenses by conferring decreased susceptibility to cationic antimicrobial (or host-defense) peptides, complement-mediated killing by human serum and intraleukocytic killing by human neutrophils compared to strains lacking this PEA decoration. Heretofore, however, it was not known if gonococci can evade autophagy and if so, whether PEA-lipid A contributes to this ability. Accordingly, by using murine macrophages and human macrophage-like phagocytic cell lines we investigated if PEA decoration of gonococcal lipid A modulates autophagy formation. We report that infection with PEA-lipid A-producing gonococci significantly reduced autophagy flux in murine and human macrophages and enhanced gonococcal survival during their association with macrophages compared to a PEA-deficient lipid A mutant. Our results provide further evidence that PEA-lipid A produced by gonococci is a critical component in the ability of this human pathogen to evade host defenses.
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Hykollari A, Eckmair B, Voglmeir J, Jin C, Yan S, Vanbeselaere J, Razzazi-Fazeli E, Wilson IBH, Paschinger K. More Than Just Oligomannose: An N-glycomic Comparison of Penicillium Species. Mol Cell Proteomics 2015; 15:73-92. [PMID: 26515459 DOI: 10.1074/mcp.m115.055061] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Indexed: 11/06/2022] Open
Abstract
N-glycosylation is an essential set of post-translational modifications of proteins; in the case of filamentous fungi, N-glycans are present on a range of secreted and cell wall proteins. In this study, we have compared the glycans released by peptide/N-glycosidase F from proteolysed cell pellets of three Penicillium species (P. dierckxii, P. nordicum and P. verrucosum that all belong to the Eurotiomycetes). Although the major structures are all within the range Hex(5-11)HexNAc(2) as shown by mass spectrometry, variations in reversed-phase chromatograms and MS/MS fragmentation patterns are indicative of differences in the actual structure. Hydrofluoric acid and mannosidase treatments revealed that the oligomannosidic glycans were not only in part modified with phosphoethanolamine residues and outer chain och1-dependent mannosylation, but that bisecting galactofuranose was present in a species-dependent manner. These data are the first to specifically show the modification of N-glycans in fungi with zwitterionic moieties. Furthermore, our results indicate that mere mass spectrometric screening is insufficient to reveal the subtly complex nature of N-glycosylation even within a single fungal genus.
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Affiliation(s)
- Alba Hykollari
- From the ‡Department für Chemie, Universität für Bodenkultur, Muthgasse 18, 1190 Wien, Austria
| | - Barbara Eckmair
- From the ‡Department für Chemie, Universität für Bodenkultur, Muthgasse 18, 1190 Wien, Austria
| | - Josef Voglmeir
- From the ‡Department für Chemie, Universität für Bodenkultur, Muthgasse 18, 1190 Wien, Austria
| | - Chunsheng Jin
- §Institutionen för Biomedicin, Göteborgs universitet, 405 30 Göteborg, Sweden
| | - Shi Yan
- From the ‡Department für Chemie, Universität für Bodenkultur, Muthgasse 18, 1190 Wien, Austria
| | - Jorick Vanbeselaere
- From the ‡Department für Chemie, Universität für Bodenkultur, Muthgasse 18, 1190 Wien, Austria
| | | | - Iain B H Wilson
- From the ‡Department für Chemie, Universität für Bodenkultur, Muthgasse 18, 1190 Wien, Austria
| | - Katharina Paschinger
- From the ‡Department für Chemie, Universität für Bodenkultur, Muthgasse 18, 1190 Wien, Austria;
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25
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Phosphoethanolamine Transferase LptA in Haemophilus ducreyi Modifies Lipid A and Contributes to Human Defensin Resistance In Vitro. PLoS One 2015; 10:e0124373. [PMID: 25902140 PMCID: PMC4406763 DOI: 10.1371/journal.pone.0124373] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/02/2015] [Indexed: 01/01/2023] Open
Abstract
Haemophilus ducreyi resists the cytotoxic effects of human antimicrobial peptides (APs), including α-defensins, β-defensins, and the cathelicidin LL-37. Resistance to LL-37, mediated by the sensitive to antimicrobial peptide (Sap) transporter, is required for H. ducreyi virulence in humans. Cationic APs are attracted to the negatively charged bacterial cell surface. In other gram-negative bacteria, modification of lipopolysaccharide or lipooligosaccharide (LOS) by the addition of positively charged moieties, such as phosphoethanolamine (PEA), confers AP resistance by means of electrostatic repulsion. H. ducreyi LOS has PEA modifications at two sites, and we identified three genes (lptA, ptdA, and ptdB) in H. ducreyi with homology to a family of bacterial PEA transferases. We generated non-polar, unmarked mutants with deletions in one, two, or all three putative PEA transferase genes. The triple mutant was significantly more susceptible to both α- and β-defensins; complementation of all three genes restored parental levels of AP resistance. Deletion of all three PEA transferase genes also resulted in a significant increase in the negativity of the mutant cell surface. Mass spectrometric analysis revealed that LptA was required for PEA modification of lipid A; PtdA and PtdB did not affect PEA modification of LOS. In human inoculation experiments, the triple mutant was as virulent as its parent strain. While this is the first identified mechanism of resistance to α-defensins in H. ducreyi, our in vivo data suggest that resistance to cathelicidin LL-37 may be more important than defensin resistance to H. ducreyi pathogenesis.
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26
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Wang G, Mishra B, Lau K, Lushnikova T, Golla R, Wang X. Antimicrobial peptides in 2014. Pharmaceuticals (Basel) 2015; 8:123-50. [PMID: 25806720 PMCID: PMC4381204 DOI: 10.3390/ph8010123] [Citation(s) in RCA: 127] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 03/16/2015] [Accepted: 03/17/2015] [Indexed: 12/13/2022] Open
Abstract
This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms.
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Affiliation(s)
- Guangshun Wang
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA.
| | - Biswajit Mishra
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
| | - Kyle Lau
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
| | - Tamara Lushnikova
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
| | - Radha Golla
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
| | - Xiuqing Wang
- Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
- Institute of Clinical Laboratory, Ningxia Medical University, Yinchuan 750004, China
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27
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Bauer ME, Shafer WM. On the in vivo significance of bacterial resistance to antimicrobial peptides. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:3101-11. [PMID: 25701234 DOI: 10.1016/j.bbamem.2015.02.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 02/04/2015] [Accepted: 02/07/2015] [Indexed: 12/17/2022]
Abstract
Antimicrobial peptides (AMPs) are at the front-line of host defense during infection and play critical roles both in reducing the microbial load early during infection and in linking innate to adaptive immunity. However, successful pathogens have developed mechanisms to resist AMPs. Although considerable progress has been made in elucidating AMP-resistance mechanisms of pathogenic bacteria in vitro, less is known regarding the in vivo significance of such resistance. Nevertheless, progress has been made in this area, largely by using murine models and, in two instances, human models of infection. Herein, we review progress on the use of in vivo infection models in AMP research and discuss the AMP resistance mechanisms that have been established by in vivo studies to contribute to microbial infection. We posit that in vivo infection models are essential tools for investigators to understand the significance to pathogenesis of genetic changes that impact levels of bacterial susceptibility to AMPs. This article is part of a Special Issue entitled: Bacterial Resistance to Antimicrobial Peptides.
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Affiliation(s)
- Margaret E Bauer
- Department of Microbiology and Immunology, Indiana University School of Medicine, 635 Barnhill Drive MS-420, Indianapolis, IN 46254, USA.
| | - William M Shafer
- Laboratories of Bacterial Pathogenesis, Veterans Affairs Medical Center, Decatur, GA 30033, USA; Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA.
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28
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Handing JW, Criss AK. The lipooligosaccharide-modifying enzyme LptA enhances gonococcal defence against human neutrophils. Cell Microbiol 2015; 17:910-21. [PMID: 25537831 DOI: 10.1111/cmi.12411] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/20/2014] [Accepted: 12/17/2014] [Indexed: 01/27/2023]
Abstract
Infection with Neisseria gonorrhoeae (Gc) is marked by an influx of neutrophils to the site of infection. Despite a robust immune response, viable Gc can be recovered from neutrophil-rich gonorrhoeal secretions. Gc enzymatically modifies the lipid A portion of lipooligosaccharide by the addition of phosphoethanolamine to the phosphate group at the 4' position. Loss of lipooligosaccharide phosphoethanolamine transferase A (LptA), the enzyme catalysing this reaction, increases bacterial sensitivity to killing by human complement and cationic antimicrobial peptides. Here, we investigated the importance of LptA for interactions between Gc and human neutrophils. We found that lptA mutant Gc was significantly more sensitive to killing by human neutrophils. Three mechanisms underlie the increased sensitivity of lptA mutant Gc to neutrophils. (i) lptA mutant Gc is more likely to reside in mature phagolysosomes than LptA-expressing bacteria. (ii) lptA mutant Gc is more sensitive to killing by components found in neutrophil granules, including CAP37/azurocidin, human neutrophil peptide 1 and the serine protease cathepsin G. (iii) lptA mutant Gc is more susceptible to killing by antimicrobial components that are exocytosed from neutrophils, including those decorating neutrophil extracellular traps. By increasing the resistance of Gc to the bactericidal activity of neutrophils, LptA-catalysed modification of lipooligosaccharide enhances survival of Gc from the human inflammatory response during acute gonorrhoea.
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Affiliation(s)
- Jonathan W Handing
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA
| | - Alison K Criss
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, USA
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29
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30
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Heimlich DR, Harrison A, Mason KM. Host Antimicrobial Peptides in Bacterial Homeostasis and Pathogenesis of Disease. Antibiotics (Basel) 2014; 3:645-76. [PMID: 26029470 PMCID: PMC4448142 DOI: 10.3390/antibiotics3040645] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/05/2014] [Accepted: 11/05/2014] [Indexed: 01/10/2023] Open
Abstract
Innate immune responses function as a first line of host defense against the development of bacterial infection, and in some cases to preserve the sterility of privileged sites in the human host. Bacteria that enter these sites must counter host responses for colonization. From the host's perspective, the innate immune system works expeditiously to minimize the bacterial threat before colonization and subsequent dysbiosis. The multifactorial nature of disease further challenges predictions of how each independent variable influences bacterial pathogenesis. From bacterial colonization to infection and through disease, the microenvironments of the host are in constant flux as bacterial and host factors contribute to changes at the host-pathogen interface, with the host attempting to eradicate bacteria and the bacteria fighting to maintain residency. A key component of this innate host response towards bacterial infection is the production of antimicrobial peptides (AMPs). As an early component of the host response, AMPs modulate bacterial load and prevent establishment of infection. Under quiescent conditions, some AMPs are constitutively expressed by the epithelium. Bacterial infection can subsequently induce production of other AMPs in an effort to maintain sterility, or to restrict colonization. As demonstrated in various studies, the absence of a single AMP can influence pathogenesis, highlighting the importance of AMP concentration in maintaining homeostasis. Yet, AMPs can increase bacterial virulence through the co-opting of the peptides or alteration of bacterial virulence gene expression. Further, bacterial factors used to subvert AMPs can modify host microenvironments and alter colonization of the residential flora that principally maintain homeostasis. Thus, the dynamic interplay between host defense peptides and bacterial factors produced to quell peptide activity play a critical role in the progression and outcome of disease.
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Affiliation(s)
- Derek R. Heimlich
- The Research Institute at Nationwide Children’s Center for Microbial Pathogenesis, Columbus, OH 43205, USA; E-Mails: (D.R.H.); (A.H.)
| | - Alistair Harrison
- The Research Institute at Nationwide Children’s Center for Microbial Pathogenesis, Columbus, OH 43205, USA; E-Mails: (D.R.H.); (A.H.)
| | - Kevin M. Mason
- The Research Institute at Nationwide Children’s Center for Microbial Pathogenesis, Columbus, OH 43205, USA; E-Mails: (D.R.H.); (A.H.)
- The Ohio State University College of Medicine, Department of Pediatrics, Columbus, OH 43205, USA
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31
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Phase-variable expression of lptA modulates the resistance of Neisseria gonorrhoeae to cationic antimicrobial peptides. Antimicrob Agents Chemother 2014; 58:4230-3. [PMID: 24820072 DOI: 10.1128/aac.03108-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphoethanolamine (PEA) decoration of lipid A produced by Neisseria gonorrhoeae has been linked to bacterial resistance to cationic antimicrobial peptides/proteins (CAMPs) and in vivo fitness during experimental infection. We now report that the lptA gene, which encodes the PEA transferase responsible for this decoration, is in an operon and that high-frequency mutation in a polynucleotide repeat within lptA can influence gonococcal resistance to CAMPs.
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32
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Abstract
The acyl chain length, number, and distribution have been considered the major factors contributing to this biological activity of lipid A. The charged head groups on the dihexosamine backbone have also been implicated in contributing to this biology. In Neisseria, it has now been shown that loss of the 4' phosphoethanolamine has an impact on virulence in an animal model and on the organism's susceptibility to cationic antimicrobial peptides. Such studies offer potential insight into targets for novel antimicrobial agents.
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