Novel inhibitors that target bacterial virulence identified via HTS against intra-macrophage survival of Shigella flexneri

Shigella flexneri is a facultative intracellular pathogen that causes shigellosis, a human diarrheal disease characterized by the destruction of the colonic epithelium. Novel antimicrobial compounds to treat infections are urgently needed due to the proliferation of bacterial antibiotic resistance a...

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Main Authors: Marija Miljkovic, Sonia Lozano, Isabel Castellote, Cristina de Cózar, Ana I. Villegas-Moreno, Pablo Gamallo, Dolores Jimenez-Alfaro Martinez, Elena Fernández-Álvaro, Lluis Ballell, George A. Garcia
Format: Article
Language:English
Published: American Society for Microbiology 2023-10-01
Series:mSphere
Subjects:
Online Access:https://journals.asm.org/doi/10.1128/msphere.00154-23
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author Marija Miljkovic
Sonia Lozano
Isabel Castellote
Cristina de Cózar
Ana I. Villegas-Moreno
Pablo Gamallo
Dolores Jimenez-Alfaro Martinez
Elena Fernández-Álvaro
Lluis Ballell
George A. Garcia
author_facet Marija Miljkovic
Sonia Lozano
Isabel Castellote
Cristina de Cózar
Ana I. Villegas-Moreno
Pablo Gamallo
Dolores Jimenez-Alfaro Martinez
Elena Fernández-Álvaro
Lluis Ballell
George A. Garcia
author_sort Marija Miljkovic
collection DOAJ
description Shigella flexneri is a facultative intracellular pathogen that causes shigellosis, a human diarrheal disease characterized by the destruction of the colonic epithelium. Novel antimicrobial compounds to treat infections are urgently needed due to the proliferation of bacterial antibiotic resistance and lack of new effective antimicrobials in the market. Our approach to find compounds that block the Shigella virulence pathway has three potential advantages: (i) resistance development should be minimized due to the lack of growth selection pressure, (ii) no resistance due to environmental antibiotic exposure should be developed since the virulence pathways are not activated outside of host infection, and (iii) the normal intestinal microbiota, which do not have the targeted virulence pathways, should be unharmed. We chose to utilize two phenotypic assays, inhibition of Shigella survival in macrophages and Shigella growth inhibition (minimum inhibitory concentration), to interrogate the 1.7 M compound screening collection subset of the GlaxoSmithKline drug discovery chemical library. A number of secondary assays on the hit compounds resulting from the primary screens were conducted, which, in combination with chemical, structural, and physical property analyses, narrowed the final hit list to 44 promising compounds for further drug discovery efforts. The rapid development of antibiotic resistance is a critical problem that has the potential of returning the world to a “pre-antibiotic” type of environment, where millions of people will die from previously treatable infections. One relatively newer approach to minimize the selection pressures for the development of resistance is to target virulence pathways. This is anticipated to eliminate any resistance selection pressure in environmental exposure to virulence-targeted antibiotics and will have the added benefit of not affecting the non-virulent microbiome. This paper describes the development and application of a simple, reproducible, and sensitive assay to interrogate an extensive chemical library in high-throughput screening format for activity against the survival of Shigella flexneri 2457T-nl in THP-1 macrophages. The ability to screen very large numbers of compounds in a reasonable time frame (~1.7 M compounds in ~8 months) distinguishes this assay as a powerful tool in further exploring new compounds with intracellular effect on S. flexneri or other pathogens with similar pathways of pathogenesis. The assay utilizes a luciferase reporter which is extremely rapid, simple, relatively inexpensive, and sensitive and possesses a broad linear range. The assay also utilized THP-1 cells that resemble primary monocytes and macrophages in morphology and differentiation properties. THP-1 cells have advantages over human primary monocytes or macrophages because they are highly plastic and their homogeneous genetic background minimizes the degree of variability in the cell phenotype (1). The intracellular and virulence-targeted selectivity of our methodology, determined via secondary screening, is an enormous advantage. Our main interest focuses on hits that are targeting virulence, and the most promising compounds with adequate physicochemical and drug metabolism and pharmacokinetic (DMPK) properties will be progressed to a suitable in vivo shigellosis model to evaluate the therapeutic potential of this approach. Additionally, compounds that act via a host-directed mechanism could be a promising source for further research given that it would allow a whole new, specific, and controlled approach to the treatment of diseases caused by some pathogenic bacteria.
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spelling doaj.art-3e669ba0e9914febb2e435207abf3db32023-10-24T16:32:15ZengAmerican Society for MicrobiologymSphere2379-50422023-10-018510.1128/msphere.00154-23Novel inhibitors that target bacterial virulence identified via HTS against intra-macrophage survival of Shigella flexneriMarija Miljkovic0Sonia Lozano1Isabel Castellote2Cristina de Cózar3Ana I. Villegas-Moreno4Pablo Gamallo5Dolores Jimenez-Alfaro Martinez6Elena Fernández-Álvaro7Lluis Ballell8George A. Garcia9Department of Medical Chemistry, College of Pharmacy, University of Michigan , Ann Arbor, Michigan, USAGSK Global Health Unit , Madrid, SpainGSK Global Health Unit , Madrid, SpainGSK Global Health Unit , Madrid, SpainGSK Global Health Unit , Madrid, SpainGSK Global Health Unit , Madrid, SpainGSK Global Health Unit , Madrid, SpainGSK Global Health Unit , Madrid, SpainGSK Global Health Unit , Madrid, SpainDepartment of Medical Chemistry, College of Pharmacy, University of Michigan , Ann Arbor, Michigan, USAShigella flexneri is a facultative intracellular pathogen that causes shigellosis, a human diarrheal disease characterized by the destruction of the colonic epithelium. Novel antimicrobial compounds to treat infections are urgently needed due to the proliferation of bacterial antibiotic resistance and lack of new effective antimicrobials in the market. Our approach to find compounds that block the Shigella virulence pathway has three potential advantages: (i) resistance development should be minimized due to the lack of growth selection pressure, (ii) no resistance due to environmental antibiotic exposure should be developed since the virulence pathways are not activated outside of host infection, and (iii) the normal intestinal microbiota, which do not have the targeted virulence pathways, should be unharmed. We chose to utilize two phenotypic assays, inhibition of Shigella survival in macrophages and Shigella growth inhibition (minimum inhibitory concentration), to interrogate the 1.7 M compound screening collection subset of the GlaxoSmithKline drug discovery chemical library. A number of secondary assays on the hit compounds resulting from the primary screens were conducted, which, in combination with chemical, structural, and physical property analyses, narrowed the final hit list to 44 promising compounds for further drug discovery efforts. The rapid development of antibiotic resistance is a critical problem that has the potential of returning the world to a “pre-antibiotic” type of environment, where millions of people will die from previously treatable infections. One relatively newer approach to minimize the selection pressures for the development of resistance is to target virulence pathways. This is anticipated to eliminate any resistance selection pressure in environmental exposure to virulence-targeted antibiotics and will have the added benefit of not affecting the non-virulent microbiome. This paper describes the development and application of a simple, reproducible, and sensitive assay to interrogate an extensive chemical library in high-throughput screening format for activity against the survival of Shigella flexneri 2457T-nl in THP-1 macrophages. The ability to screen very large numbers of compounds in a reasonable time frame (~1.7 M compounds in ~8 months) distinguishes this assay as a powerful tool in further exploring new compounds with intracellular effect on S. flexneri or other pathogens with similar pathways of pathogenesis. The assay utilizes a luciferase reporter which is extremely rapid, simple, relatively inexpensive, and sensitive and possesses a broad linear range. The assay also utilized THP-1 cells that resemble primary monocytes and macrophages in morphology and differentiation properties. THP-1 cells have advantages over human primary monocytes or macrophages because they are highly plastic and their homogeneous genetic background minimizes the degree of variability in the cell phenotype (1). The intracellular and virulence-targeted selectivity of our methodology, determined via secondary screening, is an enormous advantage. Our main interest focuses on hits that are targeting virulence, and the most promising compounds with adequate physicochemical and drug metabolism and pharmacokinetic (DMPK) properties will be progressed to a suitable in vivo shigellosis model to evaluate the therapeutic potential of this approach. Additionally, compounds that act via a host-directed mechanism could be a promising source for further research given that it would allow a whole new, specific, and controlled approach to the treatment of diseases caused by some pathogenic bacteria.https://journals.asm.org/doi/10.1128/msphere.00154-23Shigella flexneri 2457Tshigellosishigh-throughput screeningTHP-1 macrophagesintracellularvirulence
spellingShingle Marija Miljkovic
Sonia Lozano
Isabel Castellote
Cristina de Cózar
Ana I. Villegas-Moreno
Pablo Gamallo
Dolores Jimenez-Alfaro Martinez
Elena Fernández-Álvaro
Lluis Ballell
George A. Garcia
Novel inhibitors that target bacterial virulence identified via HTS against intra-macrophage survival of Shigella flexneri
mSphere
Shigella flexneri 2457T
shigellosis
high-throughput screening
THP-1 macrophages
intracellular
virulence
title Novel inhibitors that target bacterial virulence identified via HTS against intra-macrophage survival of Shigella flexneri
title_full Novel inhibitors that target bacterial virulence identified via HTS against intra-macrophage survival of Shigella flexneri
title_fullStr Novel inhibitors that target bacterial virulence identified via HTS against intra-macrophage survival of Shigella flexneri
title_full_unstemmed Novel inhibitors that target bacterial virulence identified via HTS against intra-macrophage survival of Shigella flexneri
title_short Novel inhibitors that target bacterial virulence identified via HTS against intra-macrophage survival of Shigella flexneri
title_sort novel inhibitors that target bacterial virulence identified via hts against intra macrophage survival of shigella flexneri
topic Shigella flexneri 2457T
shigellosis
high-throughput screening
THP-1 macrophages
intracellular
virulence
url https://journals.asm.org/doi/10.1128/msphere.00154-23
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