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Gray DA, Wang B, Sidarta M, Cornejo FA, Wijnheijmer J, Rani R, Gamba P, Turgay K, Wenzel M, Strahl H, Hamoen LW. Membrane depolarization kills dormant Bacillus subtilis cells by generating a lethal dose of ROS. Nat Commun 2024; 15:6877. [PMID: 39128925 PMCID: PMC11317493 DOI: 10.1038/s41467-024-51347-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 08/02/2024] [Indexed: 08/13/2024] Open
Abstract
The bactericidal activity of several antibiotics partially relies on the production of reactive oxygen species (ROS), which is generally linked to enhanced respiration and requires the Fenton reaction. Bacterial persister cells, an important cause of recurring infections, are tolerant to these antibiotics because they are in a dormant state. Here, we use Bacillus subtilis cells in stationary phase, as a model system of dormant cells, to show that pharmacological induction of membrane depolarization enhances the antibiotics' bactericidal activity and also leads to ROS production. However, in contrast to previous studies, this results primarily in production of superoxide radicals and does not require the Fenton reaction. Genetic analyzes indicate that Rieske factor QcrA, the iron-sulfur subunit of respiratory complex III, seems to be a primary source of superoxide radicals. Interestingly, the membrane distribution of QcrA changes upon membrane depolarization, suggesting a dissociation of complex III. Thus, our data reveal an alternative mechanism by which antibiotics can cause lethal ROS levels, and may partially explain why membrane-targeting antibiotics are effective in eliminating persisters.
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Affiliation(s)
- Declan A Gray
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Baddiley-Clark Building, Newcastle upon Tyne, NE2 4AX, UK
- Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, Sweden
- Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden
| | - Biwen Wang
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, C3.108, 1098 XH, Amsterdam, The Netherlands
| | - Margareth Sidarta
- Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, Sweden
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Kemigården 4, 412 96, Gothenburg, Sweden
| | - Fabián A Cornejo
- Max Planck Unit for the Science of Pathogens, Charitéplatz 1, 10117, Berlin, Germany
| | - Jurian Wijnheijmer
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, C3.108, 1098 XH, Amsterdam, The Netherlands
| | - Rupa Rani
- Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, Sweden
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Kemigården 4, 412 96, Gothenburg, Sweden
| | - Pamela Gamba
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Baddiley-Clark Building, Newcastle upon Tyne, NE2 4AX, UK
- Charles River Laboratories, Keele Science Park, Keele, ST5 5SP, UK
| | - Kürşad Turgay
- Max Planck Unit for the Science of Pathogens, Charitéplatz 1, 10117, Berlin, Germany
- Leibniz Universität Hannover, Institut für Mikrobiologie, Herrenhäuser Str. 2, 30419, Hannover, Germany
| | - Michaela Wenzel
- Centre for Antibiotic Resistance Research in Gothenburg (CARe), Gothenburg, Sweden
- Division of Chemical Biology, Department of Life Sciences, Chalmers University of Technology, Kemigården 4, 412 96, Gothenburg, Sweden
| | - Henrik Strahl
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Baddiley-Clark Building, Newcastle upon Tyne, NE2 4AX, UK
| | - Leendert W Hamoen
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Baddiley-Clark Building, Newcastle upon Tyne, NE2 4AX, UK.
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, C3.108, 1098 XH, Amsterdam, The Netherlands.
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2
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Niu H, Gu J, Zhang Y. Bacterial persisters: molecular mechanisms and therapeutic development. Signal Transduct Target Ther 2024; 9:174. [PMID: 39013893 PMCID: PMC11252167 DOI: 10.1038/s41392-024-01866-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2023] [Revised: 05/06/2024] [Accepted: 05/13/2024] [Indexed: 07/18/2024] Open
Abstract
Persisters refer to genetically drug susceptible quiescent (non-growing or slow growing) bacteria that survive in stress environments such as antibiotic exposure, acidic and starvation conditions. These cells can regrow after stress removal and remain susceptible to the same stress. Persisters are underlying the problems of treating chronic and persistent infections and relapse infections after treatment, drug resistance development, and biofilm infections, and pose significant challenges for effective treatments. Understanding the characteristics and the exact mechanisms of persister formation, especially the key molecules that affect the formation and survival of the persisters is critical to more effective treatment of chronic and persistent infections. Currently, genes related to persister formation and survival are being discovered and confirmed, but the mechanisms by which bacteria form persisters are very complex, and there are still many unanswered questions. This article comprehensively summarizes the historical background of bacterial persisters, details their complex characteristics and their relationship with antibiotic tolerant and resistant bacteria, systematically elucidates the interplay between various bacterial biological processes and the formation of persister cells, as well as consolidates the diverse anti-persister compounds and treatments. We hope to provide theoretical background for in-depth research on mechanisms of persisters and suggest new ideas for choosing strategies for more effective treatment of persistent infections.
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Affiliation(s)
- Hongxia Niu
- School of Basic Medical Science and Key Laboratory of Blood-stasis-toxin Syndrome of Zhejiang Province, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, China
| | - Jiaying Gu
- School of Basic Medical Science and Key Laboratory of Blood-stasis-toxin Syndrome of Zhejiang Province, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, China
| | - Ying Zhang
- State Key Laboratory for the Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, 310003, Zhejiang, China.
- Jinan Microecological Biomedicine Shandong Laboratory, Jinan, 250022, Shandong, China.
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3
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Pan X, Liu W, Du Q, Zhang H, Han D. Recent Advances in Bacterial Persistence Mechanisms. Int J Mol Sci 2023; 24:14311. [PMID: 37762613 PMCID: PMC10531727 DOI: 10.3390/ijms241814311] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/13/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023] Open
Abstract
The recurrence of bacterial infectious diseases is closely associated with bacterial persisters. This subpopulation of bacteria can escape antibiotic treatment by entering a metabolic status of low activity through various mechanisms, for example, biofilm, toxin-antitoxin modules, the stringent response, and the SOS response. Correspondingly, multiple new treatments are being developed. However, due to their spontaneous low abundance in populations and the lack of research on in vivo interactions between persisters and the host's immune system, microfluidics, high-throughput sequencing, and microscopy techniques are combined innovatively to explore the mechanisms of persister formation and maintenance at the single-cell level. Here, we outline the main mechanisms of persister formation, and describe the cutting-edge technology for further research. Despite the significant progress regarding study techniques, some challenges remain to be tackled.
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Affiliation(s)
- Xiaozhou Pan
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
| | - Wenxin Liu
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
| | - Qingqing Du
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
| | - Hong Zhang
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
| | - Dingding Han
- Department of Clinical Laboratory, Shanghai Children’s Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
- Institute of Pediatric Infection, Immunity, and Critical Care Medicine, School of Medicine, Shanghai Jiao Tong University, Shanghai 200062, China
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4
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Mishra A, Das A, Banerjee T. Designing New Magic Bullets to Penetrate the Mycobacterial Shield: An Arduous Quest for Promising Therapeutic Candidates. Microb Drug Resist 2023; 29:213-227. [PMID: 37015080 DOI: 10.1089/mdr.2021.0441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/06/2023] Open
Abstract
Mycobacterium spp. intimidated mankind since time immemorial. The triumph over this organism was anticipated with the introduction of potent antimicrobials in the mid-20th century. However, the emergence of drug resistance in mycobacteria, Mycobacterium tuberculosis, in particular, caused great concern for the treatment. With the enemy growing stronger, there is an immediate need to equip the therapeutic arsenal with novel and potent chemotherapeutic agents. The task seems intricating as our understanding of the dynamic nature of the mycobacteria requires intense experimentation and research. Targeting the mycobacterial cell envelope appears promising, but its versatility allows it to escape the lethal effect of the molecules acting on it. The unique ability of hiding (inactivity during latency) also assists the bacterium to survive in a drug-rich environment. The drug delivery systems also require upgradation to allow better bioavailability and tolerance in patients. Although the resistance to the novel drugs is inevitable, our commitment to the research in this area will ensure the discovery of effective weapons against this formidable opponent.
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Affiliation(s)
- Anwita Mishra
- Department of Microbiology, Mahamana Pandit Madan Mohan Malviya Cancer Centre and Homi Bhabha Cancer Hospital, Varanasi, India
| | - Arghya Das
- Department of Microbiology, National Cancer Institute, All India Institute of Medical Sciences, New Delhi, India
| | - Tuhina Banerjee
- Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University (BHU), Varanasi, India
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She P, Li Z, Li Y, Liu S, Li L, Yang Y, Zhou L, Wu Y. Pixantrone Sensitizes Gram-Negative Pathogens to Rifampin. Microbiol Spectr 2022; 10:e0211422. [PMID: 36318018 PMCID: PMC9769682 DOI: 10.1128/spectrum.02114-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/17/2022] [Indexed: 12/24/2022] Open
Abstract
The emergence of bacterial drug resistance poses a severe threat to global public health. In particular, antimicrobial-resistant pathogens lead to a high rate of treatment failure and significantly increase mortality. Repurposing FDA-approved compounds to sensitize superbugs to conventional antibiotics provides a promising strategy to alleviate such crises. Pixantrone (PIX) has been approved for treating aggressive B-cell non-Hodgkin's lymphoma. By high-throughput drug screening, we profiled the synergistic activity between PIX and rifampin (RFP) against Gram-negative extensively drug-resistant isolates by checkerboard assay. Mechanistic studies demonstrated that PIX impacted the flagellum assembly, induced irreversible intracellular reactive oxygen species accumulation and disrupted proton motive force. In addition, the combination of PIX with RFP possesses effective antimicrobial activity against multidrug-resistant strains in vivo without detected toxicity. Collectively, these results reveal the potential of PIX in combination with RFP as a therapy option for refractory infections caused by Gram-negative pathogens. IMPORTANCE Bacterial resistance has become increasingly serious because of the widespread use and abuse of antibiotics. In particular, the emergence of multidrug-resistant bacteria has posed a serious threat to human public health. Drug repurposing, the process of finding new uses for existing drugs, provide a promising pathway to solve antimicrobial resistance. Compared to the development of novel antibiotics, this strategy leverages well-characterized pharmacology and toxicology of known drugs and is more cost-effective.
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Affiliation(s)
- Pengfei She
- Department of Laboratory Medicine, The Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Zehao Li
- Department of Laboratory Medicine, The Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yimin Li
- Department of Laboratory Medicine, The Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Shasha Liu
- Department of Laboratory Medicine, The Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Linhui Li
- Department of Laboratory Medicine, The Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yifan Yang
- Department of Laboratory Medicine, The Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Linying Zhou
- Department of Laboratory Medicine, The First Hospital of Changsha, Changsha, Hunan, China
| | - Yong Wu
- Department of Laboratory Medicine, The First Hospital of Changsha, Changsha, Hunan, China
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6
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Narayanaswamy VP, Townsend SM, Loughran AJ, Wiesmann W, Baker S. Polycationic Glycopolymer Demonstrates Activity Against Persisters and Biofilms of Non-tuberculosis Mycobacteria Cystic Fibrosis Clinical Isolates in vitro. Front Microbiol 2022; 13:821820. [PMID: 35265060 PMCID: PMC8900536 DOI: 10.3389/fmicb.2022.821820] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 01/31/2022] [Indexed: 01/15/2023] Open
Abstract
Non-tuberculosis Mycobacterium (NTM) is a group of opportunistic pathogens associated with pulmonary infections that are difficult to diagnose and treat. Standard treatment typically consists of prolonged combination antibiotic therapy. Antibiotic resistance and the role of biofilms in pathogen communities, such as NTM persister cells, is an important unmet challenge that leads to increased toxicity, frequent relapse, poor clinical management, and an extended treatment period. Infection recurrence and relapse are not uncommon among individuals with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD), where thick mucus supports bacterial biofilm production and impairs mucociliary clearance. The study evaluates a membrane-active cationic glycopolymer [poly (acetyl, arginyl) glucosamine (PAAG)] being developed to support the safe and effective treatment of NTM biofilm infections. PAAG shows antibacterial activity against a wide range of pathogenic bacteria at concentrations non-toxic to human epithelial cells. Time-kill curves demonstrated PAAG's rapid bactericidal potential at concentrations as low as 1X MIC against all NTM strains tested and compared to the standard of care. PAAG treatment prevents persister formation and eradicates antibiotic-induced persister cells in planktonic NTM cultures below the limit of detection (10 colony-forming unit (CFU)/ml). Further, PAAG showed the ability to penetrate and disperse NTM biofilms formed by both rapidly and slowly growing strains, significantly reducing the biofilm biomass (p < 0.0001) compared to the untreated NTM biofilms. Microscopical examination confirmed PAAG's ability to disrupt and disperse mycobacterial biofilms. A single PAAG treatment resulted in up to a 25-fold reduction in live-labeled NTM and a 78% reduction in biofilm thickness. Similar to other polycationic molecules, PAAG's bactericidal and antibiofilm activities employ rapid permeabilization of the outer membrane of the NTM strains, and subsequently, reduce the membrane potential even at concentrations as low as 50 μg/ml (p < 0.001). The outcomes of these in vitro analyses suggest the importance of this polycationic glycopolymer, PAAG, as a potential therapeutic agent for opportunistic NTM infections.
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Affiliation(s)
| | | | | | | | - Shenda Baker
- Synedgen, Inc., Claremont, CA, United States
- Synspira Therapeutics, Inc., Framingham, MA, United States
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7
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Modak B, Girkar S, Narayan R, Kapoor S. Mycobacterial Membranes as Actionable Targets for Lipid-Centric Therapy in Tuberculosis. J Med Chem 2022; 65:3046-3065. [PMID: 35133820 DOI: 10.1021/acs.jmedchem.1c01870] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Infectious diseases remain significant health concerns worldwide, and resistance is particularly common in patients with tuberculosis caused by Mycobacterium tuberculosis. The development of anti-infectives with novel modes of action may help overcome resistance. In this regard, membrane-active agents, which modulate membrane components essential for the survival of pathogens, present attractive antimicrobial agents. Key advantages of membrane-active compounds include their ability to target slow-growing or dormant bacteria and their favorable pharmacokinetics. Here, we comprehensively review recent advances in the development of membrane-active chemotypes that target mycobacterial membranes and discuss clinically relevant membrane-active antibacterial agents that have shown promise in counteracting bacterial infections. We discuss the relationship between the membrane properties and the synthetic requirements within the chemical scaffold, as well as the limitations of current membrane-active chemotypes. This review will lay the chemical groundwork for the development of membrane-active antituberculosis agents and will foster the discovery of more effective antitubercular agents.
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Affiliation(s)
- Biswabrata Modak
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Siddhali Girkar
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Goa 403110, India
| | - Rishikesh Narayan
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Goa 403110, India
| | - Shobhna Kapoor
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India.,Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8528, Japan
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8
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Wang M, Chan EWC, Wan Y, Wong MHY, Chen S. Active maintenance of proton motive force mediates starvation-induced bacterial antibiotic tolerance in Escherichia coli. Commun Biol 2021; 4:1068. [PMID: 34521984 PMCID: PMC8440630 DOI: 10.1038/s42003-021-02612-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 08/26/2021] [Indexed: 12/15/2022] Open
Abstract
Recent evidence suggests that metabolic shutdown alone does not fully explain how bacteria exhibit phenotypic antibiotic tolerance. In an attempt to investigate the range of starvation-induced physiological responses underlying tolerance development, we found that active maintenance of the transmembrane proton motive force (PMF) is essential for prolonged expression of antibiotic tolerance in bacteria. Eradication of tolerant sub-population could be achieved by disruption of PMF using the ionophore CCCP, or through suppression of PMF maintenance mechanisms by simultaneous inhibition of the phage shock protein (Psp) response and electron transport chain (ETC) complex activities. We consider disruption of bacterial PMF a feasible strategy for treatment of chronic and recurrent bacterial infections.
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Affiliation(s)
- Miaomiao Wang
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong
| | - Edward Wai Chi Chan
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Yingkun Wan
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong
| | - Marcus Ho-Yin Wong
- State Key Laboratory of Chemical Biology and Drug Discovery, Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Sheng Chen
- Department of Infectious Diseases and Public Health, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong.
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10
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Lin S, Wade JD, Liu S. De Novo Design of Flavonoid-Based Mimetics of Cationic Antimicrobial Peptides: Discovery, Development, and Applications. Acc Chem Res 2021; 54:104-119. [PMID: 33346639 DOI: 10.1021/acs.accounts.0c00550] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The alarming rate at which pathogens are developing resistance to conventional antibiotics represents one of the major global challenges to public health care. The prevalence of multidrug-resistant microorganisms is a major impetus for the discovery and development of new antimicrobials. Nature has, to date, been the source of most of the antibiotics discovered and used, including cationic antimicrobial peptides (CAMPs). CAMPs are key components of the innate immune system that are widely found in humans, animals, plants, and microorganisms and that serve as a first line of defense for the host. The attractive features of CAMPs have led to their recognition as potential new antimicrobials. However, they possess several inherent flaws that limit their clinical application including low stability, poor oral bioavailability, poor in vivo efficacy, and a high production cost. To address these issues, small molecule-based peptidomimetic antimicrobials have been designed to biomimic the structural features and biological function of CAMPs. Plant-derived flavonoids (e.g., xanthones and flavones) are active components in traditional herbal medicines and have been reported to contain a variety of significant pharmacological actions including antibacterial, antiviral, antioxidant, and anticancer activities. Over the past decade, we have developed a new chemical strategy to design, discover, and develop xanthone- or flavone-based peptidomimetics and have designed, synthesized, and biologically evaluated a library of approximately 450 new xanthone or flavone derivatives. The designed, structurally diverse compounds can be generally classified into two subfamilies, namely, peptidic and nonpeptidic amphiphilic xanthone or flavone derivatives. In this Account, we describe our efforts on the design, synthesis, biological property evaluation, and mechanism of action model studies of synthetic mimics of CAMPs. The flavonoid compounds are an important component of these rationally designed mimics because they function as hydrophobic aromatic moieties conjugated with different length lipid moieties, behave like an unnatural hydrophobic residue, and provide a rigid scaffold, with the reduced conformational flexibility more likely to provide an active conformation. The mimics can effectively disrupt the integrity of the bacterial membranes. Our endeavors encompass design principles, chemical synthesis, in vitro screening, structural optimization, extensive structural-activity relationship analysis, and a mechanism of action study through biophysical technologies including NMR spectroscopy techniques and computer dynamics simulations, drug resistance assays, in vivo pharmaceutical kinetics (PK) analyses, and in vivo efficacy evaluations of selected promising compounds against drug-resistant bacteria and fungi. Our major contributions to the discovery and development of flavonoid-based mimics as antimicrobials include effectively addressing several limitations associated with CAMPs and have led to promising compounds with a notable potential for further development as new therapeutic antimicrobial agents for the treatment of drug-resistant bacteria- or fungi-induced infections.
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Affiliation(s)
- Shuimu Lin
- Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences & The Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
| | - John D. Wade
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria 3010, Australia
- School of Chemistry, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Shouping Liu
- Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences & The Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, Guangdong 511436, P.R. China
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11
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Khan F, Pham DTN, Tabassum N, Oloketuyi SF, Kim YM. Treatment strategies targeting persister cell formation in bacterial pathogens. Crit Rev Microbiol 2020; 46:665-688. [DOI: 10.1080/1040841x.2020.1822278] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Fazlurrahman Khan
- Institute of Food Science, Pukyong National University, Busan, Korea
| | - Dung Thuy Nguyen Pham
- Department of Food Science and Technology, Pukyong National University, Busan, Korea
| | - Nazia Tabassum
- Industrial Convergence Bionix Engineering, Pukyong National University, Busan, Korea
| | | | - Young-Mog Kim
- Institute of Food Science, Pukyong National University, Busan, Korea
- Department of Food Science and Technology, Pukyong National University, Busan, Korea
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12
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Salcedo-Sora JE, Kell DB. A Quantitative Survey of Bacterial Persistence in the Presence of Antibiotics: Towards Antipersister Antimicrobial Discovery. Antibiotics (Basel) 2020; 9:E508. [PMID: 32823501 PMCID: PMC7460088 DOI: 10.3390/antibiotics9080508] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/08/2020] [Accepted: 08/11/2020] [Indexed: 12/17/2022] Open
Abstract
Background: Bacterial persistence to antibiotics relates to the phenotypic ability to survive lethal concentrations of otherwise bactericidal antibiotics. The quantitative nature of the time-kill assay, which is the sector's standard for the study of antibiotic bacterial persistence, is an invaluable asset for global, unbiased, and cross-species analyses. Methods: We compiled the results of antibiotic persistence from antibiotic-sensitive bacteria during planktonic growth. The data were extracted from a sample of 187 publications over the last 50 years. The antibiotics used in this compilation were also compared in terms of structural similarity to fluorescent molecules known to accumulate in Escherichia coli. Results: We reviewed in detail data from 54 antibiotics and 36 bacterial species. Persistence varies widely as a function of the type of antibiotic (membrane-active antibiotics admit the fewest), the nature of the growth phase and medium (persistence is less common in exponential phase and rich media), and the Gram staining of the target organism (persistence is more common in Gram positives). Some antibiotics bear strong structural similarity to fluorophores known to be taken up by E. coli, potentially allowing competitive assays. Some antibiotics also, paradoxically, seem to allow more persisters at higher antibiotic concentrations. Conclusions: We consolidated an actionable knowledge base to support a rational development of antipersister antimicrobials. Persistence is seen as a step on the pathway to antimicrobial resistance, and we found no organisms that failed to exhibit it. Novel antibiotics need to have antipersister activity. Discovery strategies should include persister-specific approaches that could find antibiotics that preferably target the membrane structure and permeability of slow-growing cells.
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Affiliation(s)
- Jesus Enrique Salcedo-Sora
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Biosciences Building, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK;
| | - Douglas B. Kell
- Department of Biochemistry and Systems Biology, Institute of Systems, Molecular and Integrative Biology, Biosciences Building, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK;
- Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Building 220, Kemitorvet, 2800 Kgs. Lyngby, Denmark
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13
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Khara JS, Mojsoska B, Mukherjee D, Langford PR, Robertson BD, Jenssen H, Ee PLR, Newton SM. Ultra-Short Antimicrobial Peptoids Show Propensity for Membrane Activity Against Multi-Drug Resistant Mycobacterium tuberculosis. Front Microbiol 2020; 11:417. [PMID: 32256474 PMCID: PMC7089965 DOI: 10.3389/fmicb.2020.00417] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/27/2020] [Indexed: 11/13/2022] Open
Abstract
Tuberculosis (TB) results in both morbidity and mortality on a global scale. With drug resistance on the increase, there is an urgent need to develop novel anti-mycobacterials. Thus, we assessed the anti-mycobacterial potency of three novel synthetic peptoids against drug-susceptible and multi-drug resistant (MDR) Mycobacterium tuberculosis in vitro using Minimum Inhibitory Concentration, killing efficacy and intracellular growth inhibition assays, and in vivo against mycobacteria infected BALB/c mice. In addition, we verified cell selectivity using mammalian cells to assess peptoid toxicity. The mechanism of action was determined using flow cytometric analysis, and microfluidic live-cell imaging with time-lapse microscopy and uptake of propidium iodide. Peptoid BM 2 demonstrated anti-mycobacterial activity against both drug sensitive and MDR M. tuberculosis together with an acceptable toxicity profile that showed selectivity between bacterial and mammalian membranes. The peptoid was able to efficiently kill mycobacteria both in vitro and intracellularly in murine RAW 264.7 macrophages, and significantly reduced bacterial load in the lungs of infected mice. Flow cytometric and time lapse fluorescence microscopy indicate mycobacterial membrane damage as the likely mechanism of action. These data demonstrate that peptoids are a novel class of antimicrobial which warrant further investigation and development as therapeutics against TB.
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Affiliation(s)
- Jasmeet Singh Khara
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Biljana Mojsoska
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - Devika Mukherjee
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Paul R. Langford
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Brian D. Robertson
- MRC Centre for Molecular Bacteriology and Infection, Department of Infectious Disease, Imperial College London, London, United Kingdom
| | - Håvard Jenssen
- Department of Science and Environment, Roskilde University, Roskilde, Denmark
| | - Pui Lai Rachel Ee
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Sandra M. Newton
- Section of Paediatric Infectious Disease, Department of Infectious Disease, Imperial College London, London, United Kingdom
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14
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Abstract
Aim To demonstrate that myrrh oil preferentially kills nongrowing bacteria and causes no resistance development. Method Growth inhibition was determined on regular plates or plates without nutrients, which were later overlaid with soft agar containing nutrients to continue growth. Killing experiments were done in broth and in buffer without nutrients. Results Bacterial cells were inhibited preferentially in the absence of nutrients or when growth was halted by a bacteriostatic antibiotic. After five passages in myrrh oil, surviving colonies showed no resistance to the antibiotic. Conclusion Myrrh oil has the potential to be a commercially viable antibiotic that kills persister cells and causes no resistance development. This is a rare example of an antibiotic that can preferentially kill nongrowing bacteria.
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15
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Wang H, Song Z, Gu J, Li S, Wu Y, Han H. Nitrogen-Doped Carbon Quantum Dots for Preventing Biofilm Formation and Eradicating Drug-Resistant Bacteria Infection. ACS Biomater Sci Eng 2019; 5:4739-4749. [PMID: 33448817 DOI: 10.1021/acsbiomaterials.9b00583] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The development of novel antimicrobial agents is a top priority in the fight against drug-resistant bacteria. Here, we synthesized a green nanoantibiotic, nitrogen-doped carbon quantum dots (N-CQDs) from bis-quaternary ammonium salt (BQAS) as carbon and nitrogen sources. The as-obtained N-CQDs possess high antibacterial activity (>99%) against both methicillin-resistant Staphylococcus aureus (MRSA) and Ampicillin-resistant Escherichia coli bacteria in vitro than some known clinical antibiotics (vancomycin and gentamicin). The N-CQDs can kill MRSA pathogens without inducing resistance, prevent biofilm formation and eliminate established biofilm and persister cells. The treatment of N-CQDs can significantly reduce the amount of bacteria on the infected tissue and accelerate wound healing. The N-CQDs are positively charged, thus enabling them to interact with bacterial cell membrane through electrostatic interaction, leading to severe damage and an increased permeability of the cell membrane, which further promotes the penetration of N-CQDs into the membrane and induces the degradation of DNA by N-CQDs generated reactive oxygen species. The N-CQDs also play a role in obstructing the intracellular metabolic pathways of MRSA. The overall data demonstrate the green nanoantibiotic as an excellent eradicator of biofilm and persister cells as well as a promising antibacterial candidate for treating infections induced by drug-resistant bacteria.
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16
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Shetty A, Xu Z, Lakshmanan U, Hill J, Choong ML, Chng SS, Yamada Y, Poulsen A, Dick T, Gengenbacher M. Novel Acetamide Indirectly Targets Mycobacterial Transporter MmpL3 by Proton Motive Force Disruption. Front Microbiol 2018; 9:2960. [PMID: 30564212 PMCID: PMC6289072 DOI: 10.3389/fmicb.2018.02960] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 11/16/2018] [Indexed: 02/05/2023] Open
Abstract
To identify novel inhibitors of Mycobacterium tuberculosis cell envelope biosynthesis, we employed a two-step approach. First, we screened the diverse synthetic small molecule 71,544-compound Enamine library for growth inhibitors using the non-pathogenic surrogate Mycobacterium bovis BCG as screening strain and turbidity as readout. Second, 16 confirmed hits were tested for their ability to induce the cell envelope stress responsive promoter piniBAC controlling expression of red fluorescent protein in an M. bovis BCG reporter strain. Using a fluorescence readout, the acetamide E11 was identified. Resistant mutant selection and whole genome sequencing revealed the mycolic acid transporter Mmpl3 as a candidate target of E11. Biochemical analysis using mycobacterial spheroplasts and various membrane assays suggest that E11 indirectly inhibits MmpL3-facilitated translocation of trehalose monomycolates by proton motive force disruption. E11 showed potent bactericidal activity against growing and non-growing M. tuberculosis, low cytotoxic, and hemolytic activity and a dynamic structure activity relationship. In addition to activity against M. tuberculosis, E11 was active against the non-tuberculous mycobacterium M. abscessus, an emerging opportunistic pathogen. In conclusion, we identified a novel bactericidal anti-mycobacterial lead compound targeting MmpL3 providing an attractive starting point for optimization.
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Affiliation(s)
- Annanya Shetty
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Antimicrobial Drug Discovery Laboratory, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Zhujun Xu
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | | | - Jeffrey Hill
- Experimental Therapeutics Center, ASTAR, Singapore, Singapore
| | | | - Shu-Sin Chng
- Department of Chemistry, National University of Singapore, Singapore, Singapore.,Singapore Center for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
| | - Yoshiyuki Yamada
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Anders Poulsen
- Experimental Therapeutics Center, ASTAR, Singapore, Singapore
| | - Thomas Dick
- Antimicrobial Drug Discovery Laboratory, Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Public Health Research Institute, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
| | - Martin Gengenbacher
- Public Health Research Institute, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
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17
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Sulaiman JE, Hao C, Lam H. Specific Enrichment and Proteomics Analysis of Escherichia coli Persisters from Rifampin Pretreatment. J Proteome Res 2018; 17:3984-3996. [PMID: 30336045 DOI: 10.1021/acs.jproteome.8b00625] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Bacterial persisters, a dormant and multidrug tolerant subpopulation that are able to resuscitate after antibiotic treatment, have recently received considerable attention as a major cause of relapse of various infectious diseases in the clinic. However, because of their low abundance and inherent transience, it is extremely difficult to study them by proteomics. Here we developed a magnetic-beads-based separation approach to enrich Escherichia coli persisters and then subjected them to shotgun proteomics. Rifampin pretreatment was employed to increase persister formation, and the resulting cells were exposed to a high concentration of ampicillin (10× MIC) to remove nonpersisters. The survivors were analyzed by spectral counting-based quantitative proteomics. On average, 710 proteins were identified at a false discovery rate of 0.01 for enriched E. coli persisters. By spectral counting-based quantification, 105 proteins (70 down-regulated, 35 up-regulated) were shown to be differentially expressed compared with normal cells. A comparison of the differentially expressed proteins between the magnetic beads-enriched persisters and nonenriched persisters (a mixture of persisters and intact dead cells) shows only around half (∼58%) overlap and different protein-protein interaction networks. This suggest that persister enrichment is important to eliminate the cumulative effect of dead cells that will obscure the proteome of persisters. As expected, proteins involved in carbohydrate metabolism, fatty acid and amino acid biosynthesis, and bacterial chemotaxis were found to be down-regulated in the persisters. Interestingly, membrane proteins including some transport proteins were up-regulated, indicating that they might be important for the drug tolerance of persisters. Knockout of the pal gene expressing peptidoglycan-associated lipoprotein, one of the most up-regulated proteins detected in persisters, led to 10-fold reduced persister formation under ampicillin treatment.
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Affiliation(s)
- Jordy Evan Sulaiman
- Department of Chemical and Biological Engineering , The Hong Kong University of Science & Technology , Clear Water Bay , Kowloon , Hong Kong
| | - Chunlin Hao
- Department of Chemical and Biological Engineering , The Hong Kong University of Science & Technology , Clear Water Bay , Kowloon , Hong Kong
| | - Henry Lam
- Department of Chemical and Biological Engineering , The Hong Kong University of Science & Technology , Clear Water Bay , Kowloon , Hong Kong
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18
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Mandakhalikar KD, Wang R, Rahmat JN, Chiong E, Neoh KG, Tambyah PA. Restriction of in vivo infection by antifouling coating on urinary catheter with controllable and sustained silver release: a proof of concept study. BMC Infect Dis 2018; 18:370. [PMID: 30081836 PMCID: PMC6090839 DOI: 10.1186/s12879-018-3296-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Accepted: 08/01/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Catheter Associated Urinary Tract Infections are among the most common urological infections world-wide. Bacterial biofilms and encrustation cause significant complications in patients with urinary catheters. The objective of the study is to demonstrate the efficacy and safety of an anti-microbial and anti-encrustation silver nanoparticle (AgNP) coating on silicone urinary catheter in two different animal models. METHODS Antifouling coating (P3) was prepared with alternate layers of polydopamine and AgNP and an outermost antifouling layer. Sixteen C57BL/6 female mice and two female PWG Micropigs® were used to perform the experiments. In mice, a 5 mm long silicone catheter with or without P3 was transurethrally placed into the urinary bladder. Micropigs were transurethrally implanted - one with P3 silicone catheter and the other with commercially available silver coated silicone catheter. Both models were challenged with E. coli. Bacteriuria was evaluated routinely and upon end of study (2 weeks for mice, 3 weeks for micropigs), blood, catheters and bladders were harvested and analysed for bacterial colonization and encrustation as well as for toxicity. RESULTS Lower bacterial colonization was seen on P3 catheters as well as in bladders of animals with P3 catheter. Bacteriuria was consistently less in mice with P3 catheter than with uncoated catheters. Encrustation was lower on P3 catheter and in bladder of micropig with P3 catheter. No significant toxicity of P3 was observed in mice or in micropig as compared to controls. The numbers were small in this proof of concept study and technical issues were noted especially with the porcine model. CONCLUSIONS Antifouling P3 coating reduces bacterial colonization on catheter and in animal bladders without causing any considerable toxicity for 2 to 3 weeks. This novel coating could potentially reduce the complications of indwelling urethral catheters.
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Affiliation(s)
- Kedar Diwakar Mandakhalikar
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 1E, Kent Ridge Road, NUHS Tower Block, Level 10, Singapore, 119228, Singapore.
| | - Rong Wang
- ACI Medical Pte Ltd, Singapore, 069534, Singapore
| | - Juwita N Rahmat
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119228, Singapore
| | - Edmund Chiong
- Department of Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 119228, Singapore
| | - Koon Gee Neoh
- Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117585, Singapore
| | - Paul A Tambyah
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 1E, Kent Ridge Road, NUHS Tower Block, Level 10, Singapore, 119228, Singapore
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19
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Chen H, Nyantakyi SA, Li M, Gopal P, Aziz DB, Yang T, Moreira W, Gengenbacher M, Dick T, Go ML. The Mycobacterial Membrane: A Novel Target Space for Anti-tubercular Drugs. Front Microbiol 2018; 9:1627. [PMID: 30072978 PMCID: PMC6060259 DOI: 10.3389/fmicb.2018.01627] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/28/2018] [Indexed: 01/09/2023] Open
Abstract
Tuberculosis (TB) poses an enduring threat to global health. Consistently ranked among the top 10 causes of death worldwide since 2000, TB has now exceeded HIV-AIDS in terms of deaths inflicted by a single infectious agent. In spite of recently declining TB incident rates, these decreases have been incremental and fall short of threshold levels required to end the global TB epidemic. As in other infectious diseases, the emergence of resistant organisms poses a major impediment to effective TB control. Resistance in mycobacteria may evolve from genetic mutations in target genes which are transmitted during cell multiplication from mother cells to their progeny. A more insidious form of resistance involves sub-populations of non-growing (“dormant”) mycobacterial persisters. Quiescent and genetically identical to their susceptible counterparts, persisters exhibit non-inheritable drug tolerance. Their prevalence account for the protracted treatment period that is required for the treatment of TB. In order to improve the efficacy of treatment against mycobacterial persisters and drug-resistant organisms, novel antitubercular agents are urgently required. Selective targeting of bacterial membranes has been proposed as a viable therapeutic strategy against infectious diseases. The underpinning rationale is that a functionally intact cell membrane is vital for both replicating and dormant bacteria. Perturbing the membrane would thus disrupt a multitude of embedded targets with lethal pleiotropic consequences, besides limiting the emergence of resistant strains. There is growing interest in exploring small molecules as selective disruptors of the mycobacterial membrane. In this review, we examined the recent literature on different chemotypes with membrane perturbing properties, the mechanisms by which they induce membrane disruption and their potential as anti-TB agents. Cationic amphiphilicity is a signature motif that is required of membrane targeting agents but adherence to this broad physical requirement does not necessarily translate to conformity in terms of biological outcomes. Nor does it ensure selective targeting of mycobacterial membranes. These are unresolved issues that require further investigation.
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Affiliation(s)
- Huan Chen
- Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Samuel A Nyantakyi
- Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Ming Li
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Pooja Gopal
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Dinah B Aziz
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Tianming Yang
- Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Wilfried Moreira
- Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, Antimicrobial Resistance Singapore, Singapore, Singapore
| | - Martin Gengenbacher
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Thomas Dick
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, United States
| | - Mei L Go
- Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore, Singapore
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20
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Chen BC, Lin CX, Chen NP, Gao CX, Zhao YJ, Qian CD. Phenanthrene Antibiotic Targets Bacterial Membranes and Kills Staphylococcus aureus With a Low Propensity for Resistance Development. Front Microbiol 2018; 9:1593. [PMID: 30065715 PMCID: PMC6056686 DOI: 10.3389/fmicb.2018.01593] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 06/26/2018] [Indexed: 11/13/2022] Open
Abstract
New classes of antibiotics with different mechanisms of action are urgently required for combating antimicrobial resistance. Blestriacin, a dihydro-biphenanthrene with significant antibacterial activity, was recently isolated from the fibrous roots of Bletilla striata. Here, we report the further characterization of the antimicrobial potential and mode of action of blestriacin. The phenanthrene compound inhibited the growth of all tested clinical isolates of Staphylococcus aureus including methicillin-resistant S. aureus (MRSA). The minimum inhibitory concentrations (MICs) of blestriacin against these pathogens ranged from 2 to 8 μg/mL. Minimum bactericidal concentration (MBC) tests were conducted, and the results demonstrated that blestriacin was bactericidal against S. aureus. This effect was confirmed by the time-kill assays. At bactericidal concentrations, blestriacin caused loss of membrane potential in B. subtilis and S. aureus and disrupted the bacterial membrane integrity of the two strains. The spontaneous mutation frequency of S. aureus to blestriacin was determined to be lower than 10-9. The selection and whole genome sequencing of the blestriacin –resistant mutants of S. aureus indicated that the development of blestriacin resistance in S. aureus involves mutations in multi-genes. All these observations can be rationalized by the suggestion that membrane is a biological target of blestriacin.
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Affiliation(s)
- Bo-Chen Chen
- Institute of Molecular Medicine, College of Life Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Chang-Xin Lin
- Institute of Molecular Medicine, College of Life Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Ni-Pi Chen
- Institute of Molecular Medicine, College of Life Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Cheng-Xian Gao
- Institute of Molecular Medicine, College of Life Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Ying-Jie Zhao
- College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou, China
| | - Chao-Dong Qian
- Institute of Molecular Medicine, College of Life Science, Zhejiang Chinese Medical University, Hangzhou, China
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21
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Machado D, Girardini M, Viveiros M, Pieroni M. Challenging the Drug-Likeness Dogma for New Drug Discovery in Tuberculosis. Front Microbiol 2018; 9:1367. [PMID: 30018597 PMCID: PMC6037898 DOI: 10.3389/fmicb.2018.01367] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 06/06/2018] [Indexed: 01/28/2023] Open
Abstract
The emergence of multi- and extensively drug resistant tuberculosis worldwide poses a great threat to human health and highlight the need to discover and develop new, effective and inexpensive antituberculosis agents. High-throughput screening assays against well-validated drug targets and structure based drug design have been employed to discover new lead compounds. However, the great majority fail to demonstrate any antimycobacterial activity when tested against Mycobacterium tuberculosis in whole-cell screening assays. This is mainly due to some of the intrinsic properties of the bacilli, such as the extremely low permeability of its cell wall, slow growth, drug resistance, drug tolerance, and persistence. In this sense, understanding the pathways involved in M. tuberculosis drug tolerance, persistence, and pathogenesis, may reveal new approaches for drug development. Moreover, the need for compounds presenting a novel mode of action is of utmost importance due to the emergence of resistance not only to the currently used antituberculosis agents, but also to those in the pipeline. Cheminformatics studies have shown that drugs endowed with antituberculosis activity have the peculiarity of being more lipophilic than many other antibacterials, likely because this leads to improved cell penetration through the extremely waxy mycobacterial cell wall. Moreover, the interaction of the lipophilic moiety with the membrane alters its stability and functional integrity due to the disruption of the proton motive force, resulting in cell death. When a ligand-based medicinal chemistry campaign is ongoing, it is always difficult to predict whether a chemical modification or a functional group would be suitable for improving the activity. Nevertheless, in the “instruction manual” of medicinal chemists, certain functional groups or certain physicochemical characteristics (i.e., high lipophilicity) are considered red flags to look out for in order to safeguard drug-likeness and avoid attritions in the drug discovery process. In this review, we describe how antituberculosis compounds challenge established rules such as the Lipinski's “rule of five” and how medicinal chemistry for antituberculosis compounds must be thought beyond such dogmatic schemes.
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Affiliation(s)
- Diana Machado
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisbon, Portugal
| | - Miriam Girardini
- P4T Group, Department of Food and Drug, University of Parma, Parma, Italy
| | - Miguel Viveiros
- Global Health and Tropical Medicine, GHTM, Instituto de Higiene e Medicina Tropical, IHMT, Universidade Nova de Lisboa, UNL, Lisbon, Portugal
| | - Marco Pieroni
- P4T Group, Department of Food and Drug, University of Parma, Parma, Italy
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22
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Extraction and quantification of biofilm bacteria: Method optimized for urinary catheters. Sci Rep 2018; 8:8069. [PMID: 29795121 PMCID: PMC5966383 DOI: 10.1038/s41598-018-26342-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 05/08/2018] [Indexed: 12/13/2022] Open
Abstract
Bacterial biofilms are responsible for the failure of many medical devices such as urinary catheters and are associated with many infectious and non-infectious complications. Preclinical and clinical evaluation of novel catheter coatings to prevent these infections needs to accurately quantify the bacterial load in the biofilm in vitro and ex vivo. There is currently no uniform gold standard for biofilm quantification for different surfaces and established biofilms. We have tried to establish a simple, accurate and reproducible method for extraction and measurement of biofilm bacteria on indwelling catheters, using a combination of vortexing and sonication. We demonstrate the usefulness of this method for catheters of different sizes - 3 Fr to 14 Fr - in vitro, in murine and porcine models, and indwelling in human clinical subjects. We also demonstrate consistent results with complex and polymicrobial biofilms. We believe that this standardized reproducible method will assist the assessment of biofilms in general and urological devices in particular in efforts to harness novel technologies to prevent healthcare associated infections.
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23
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Fighting bacterial persistence: Current and emerging anti-persister strategies and therapeutics. Drug Resist Updat 2018; 38:12-26. [DOI: 10.1016/j.drup.2018.03.002] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/07/2018] [Accepted: 03/25/2018] [Indexed: 01/13/2023]
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24
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Wu ML, Aziz DB, Dartois V, Dick T. NTM drug discovery: status, gaps and the way forward. Drug Discov Today 2018; 23:1502-1519. [PMID: 29635026 DOI: 10.1016/j.drudis.2018.04.001] [Citation(s) in RCA: 174] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/09/2018] [Accepted: 04/03/2018] [Indexed: 12/22/2022]
Abstract
Incidence of pulmonary diseases caused by non-tuberculous mycobacteria (NTM), relatives of Mycobacterium tuberculosis, is increasing at an alarming rate, surpassing tuberculosis in many countries. Current chemotherapies require long treatment times and the clinical outcomes are often disappointing. There is an urgent medical need to discover and develop new, more-efficacious anti-NTM drugs. In this review, we summarize the current status of NTM drug development, and highlight knowledge gaps and scientific obstacles in NTM drug discovery. We propose strategies to reduce biological uncertainties and to begin to populate a NTM drug pipeline with attractive leads and drug candidates.
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Affiliation(s)
- Mu-Lu Wu
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive, 117599, Singapore
| | - Dinah B Aziz
- Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 14 Medical Drive, 117599, Singapore
| | - Véronique Dartois
- Public Health Research Institute, New Jersey Medical School, Rutgers, The State University of New Jersey, 225 Warren Street, Newark, NJ 07103, USA
| | - Thomas Dick
- Public Health Research Institute, New Jersey Medical School, Rutgers, The State University of New Jersey, 225 Warren Street, Newark, NJ 07103, USA.
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25
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Whole-Cell Screen of Fragment Library Identifies Gut Microbiota Metabolite Indole Propionic Acid as Antitubercular. Antimicrob Agents Chemother 2018; 62:AAC.01571-17. [PMID: 29229639 PMCID: PMC5826148 DOI: 10.1128/aac.01571-17] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/29/2017] [Indexed: 12/22/2022] Open
Abstract
Several key antituberculosis drugs, including pyrazinamide, with a molecular mass of 123.1 g/mol, are smaller than the usual drug-like molecules. Current drug discovery efforts focus on the screening of larger compounds with molecular masses centered around 400 to 500 g/mol. Fragment (molecular mass < 300 g/mol) libraries have not been systematically explored for antitubercular activity. Here we screened a collection of 1,000 fragments, present in the Maybridge Ro3 library, for whole-cell activity against Mycobacterium tuberculosis. Twenty-nine primary hits showed dose-dependent growth inhibition equal to or better than that of pyrazinamide. The most potent hit, indole propionic acid [IPA; 3-(1H-indol-3-yl)propanoic acid], a metabolite produced by the gut microbiota, was profiled in vivo. The molecule was well tolerated in mice and showed adequate pharmacokinetic properties. In a mouse model of acute M. tuberculosis infection, IPA reduced the bacterial load in the spleen 7-fold. Our results suggest that IPA should be evaluated as an add-on to current regimens and that fragment libraries should be further explored to identify antimycobacterial lead candidates.
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26
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27
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Yang T, Moreira W, Nyantakyi SA, Chen H, Aziz DB, Go ML, Dick T. Amphiphilic Indole Derivatives as Antimycobacterial Agents: Structure–Activity Relationships and Membrane Targeting Properties. J Med Chem 2017; 60:2745-2763. [DOI: 10.1021/acs.jmedchem.6b01530] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Tianming Yang
- Department
of Pharmacy and ‡Department of Microbiology and Immunology, National University of Singapore, Singapore 117543, Singapore
| | - Wilfried Moreira
- Department
of Pharmacy and ‡Department of Microbiology and Immunology, National University of Singapore, Singapore 117543, Singapore
| | - Samuel Agyei Nyantakyi
- Department
of Pharmacy and ‡Department of Microbiology and Immunology, National University of Singapore, Singapore 117543, Singapore
| | - Huan Chen
- Department
of Pharmacy and ‡Department of Microbiology and Immunology, National University of Singapore, Singapore 117543, Singapore
| | - Dinah binte Aziz
- Department
of Pharmacy and ‡Department of Microbiology and Immunology, National University of Singapore, Singapore 117543, Singapore
| | - Mei-Lin Go
- Department
of Pharmacy and ‡Department of Microbiology and Immunology, National University of Singapore, Singapore 117543, Singapore
| | - Thomas Dick
- Department
of Pharmacy and ‡Department of Microbiology and Immunology, National University of Singapore, Singapore 117543, Singapore
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28
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Van den Bergh B, Fauvart M, Michiels J. Formation, physiology, ecology, evolution and clinical importance of bacterial persisters. FEMS Microbiol Rev 2017; 41:219-251. [DOI: 10.1093/femsre/fux001] [Citation(s) in RCA: 217] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 01/12/2017] [Indexed: 12/19/2022] Open
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29
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Gold B, Nathan C. Targeting Phenotypically Tolerant Mycobacterium tuberculosis. Microbiol Spectr 2017; 5:10.1128/microbiolspec.TBTB2-0031-2016. [PMID: 28233509 PMCID: PMC5367488 DOI: 10.1128/microbiolspec.tbtb2-0031-2016] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Indexed: 01/08/2023] Open
Abstract
While the immune system is credited with averting tuberculosis in billions of individuals exposed to Mycobacterium tuberculosis, the immune system is also culpable for tempering the ability of antibiotics to deliver swift and durable cure of disease. In individuals afflicted with tuberculosis, host immunity produces diverse microenvironmental niches that support suboptimal growth, or complete growth arrest, of M. tuberculosis. The physiological state of nonreplication in bacteria is associated with phenotypic drug tolerance. Many of these host microenvironments, when modeled in vitro by carbon starvation, complete nutrient starvation, stationary phase, acidic pH, reactive nitrogen intermediates, hypoxia, biofilms, and withholding streptomycin from the streptomycin-addicted strain SS18b, render M. tuberculosis profoundly tolerant to many of the antibiotics that are given to tuberculosis patients in clinical settings. Targeting nonreplicating persisters is anticipated to reduce the duration of antibiotic treatment and rate of posttreatment relapse. Some promising drugs to treat tuberculosis, such as rifampin and bedaquiline, only kill nonreplicating M. tuberculosisin vitro at concentrations far greater than their minimal inhibitory concentrations against replicating bacilli. There is an urgent demand to identify which of the currently used antibiotics, and which of the molecules in academic and corporate screening collections, have potent bactericidal action on nonreplicating M. tuberculosis. With this goal, we review methods of high-throughput screening to target nonreplicating M. tuberculosis and methods to progress candidate molecules. A classification based on structures and putative targets of molecules that have been reported to kill nonreplicating M. tuberculosis revealed a rich diversity in pharmacophores.
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Affiliation(s)
- Ben Gold
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, 10065
| | - Carl Nathan
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, 10065
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Amphiphilic xanthones as a potent chemical entity of anti-mycobacterial agents with membrane-targeting properties. Eur J Med Chem 2016; 123:684-703. [PMID: 27517813 DOI: 10.1016/j.ejmech.2016.07.068] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 07/26/2016] [Accepted: 07/27/2016] [Indexed: 12/31/2022]
Abstract
Tuberculosis (TB) remains a deadly disease and infects one-third of the world's population. Given the low success rates encountered in clinical development, there is an urgent need to identify structurally novel antimicrobials for tuberculosis. The present report details the anti-mycobacterial activities, structure-activity relationships (SARs) and mechanism of action of amphiphilic xanthone derivatives. The xanthones exhibited potent MIC, rapid time-kill and no cross-resistance with the current anti-TB drugs. Evidence is presented that these compounds disrupted the inner membrane and led to ATP depletion. Amphiphilic xanthone derivatives exhibited superior metabolic stability, low cytotoxicity and low activity against the common cytochrome P450. Compound 5 was selected for an in vivo pharmacokinetic study. Its bioavailability at an oral dose of 2 mg/kg was 15%. The xanthones thuse provide valuable insight for the development of a new class of membrane targeting antimycobacterial agents that may assist in overcoming the limitations of the current TB medications.
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