Name: system for efficacy and cytotoxicity screening of inhibitors targeting intracellular mycobacterium tuberculosis
Uploaded: 2017-04-05T14:30:00.000+00:00
Duration: 9 min 57 s
Description: Watch this Scientific Journal Video about System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis at JoVE.com

This work was supported by BC Lung Association and Mitacs.

1. Bakterienstamm und Wachstumsmedium <ol><li> Make-Albumin-Dextrose und Salz-Stammlösung (ADS) durch Solubilisieren von 25 g Rinderserumalbumin, 10,0 g Dextrose und 4,05 g Natriumchlorid in 460 ml deionisiertem Wasser. Filter-Sterilisieren der ADS und lagere bei 4 ° C. </li><li> Make 7H9 Brühe durch Zugabe von 4,7 g 7H9 Pulver und 2 ml Glycerin zu 900 ml gereinigtem Wasser. Autoklaviert die 7H9-Bouillon bei 121 ° C für 10 min und läßt es vor dem Fortfahren auf Raumtemperatur abkühlen gelassen. Machen 7H9ADST durch Zugabe von 100 ml ADS und 0,5 ml Tween 80 bis 900 ml 7H9-Bouillon. Lagerung bei 4 ° C. </li><li> Man wiegt 50 mg Kanamycinsulfat und löst in 1 ml entionisiertem Wasser; die Endkonzentration beträgt 50 mg / mL. Filter-sterilisiert und bei -20 ° C. In 0,5 ml Kanamycin Stammlösung pro 1 l 7H9ADST. HINWEIS: Dieses Medium sollte frisch hergestellt werden, so skaliert die Volumina in geeigneter Weise entsprechend der Kultur Größe. </li><li> Wachsen M. tuberculosis in 7H9ADST mit Kanamycin in Kultur steht. Schütteln Sie die Kultur täglich und verdünnen Sie es, bevor die OD 600 1,0 erreicht Verklumpen zu vermeiden. HINWEIS: Der Stamm M. tuberculosis für die Entwicklung dieses Verfahrens verwendet H37Rv wurde mit Plasmid pJAK2.A 12 umgewandelt. pJAK2.A ist ein integratives Plasmid basiert auf dem Vektor pMV361, die aus dem hsp60 Promotor Expression auf hohem Niveau des Glühwürmchen - Luciferase - Gens ermöglicht , und kann unter Verwendung von Kanamycin selektiert werden. </li></ol> 2. THP-1 Medium und Wartung <ol><li> Fügen Sie 50 ml hitzeinaktiviertem fötales Rinderserum (FBS) und 5 ml 200 mM L-Glutamin und 500 ml RPMI 1640-Medium RPMI unvollständig (ca. 10% FBS und 2 mM Glutamin) zu machen. </li><li> Pflegen einer THP-1 - Zellkultur nach Standardprotokoll 13. THP-1-Zellen in RPMI unvollständigem Medium kurz, wachsen, während eine Zelldichte von 0,2 bis 1 Million pro ml Medium zwischen pas AufrechterhaltenWeisen. </li></ol> 3. Hochdurchsatz - Screening intrazellulärer Mit Luziferase-exprimierenden M. tuberculosis H37Rv <ol><li> Die optische Dichte einer aktiv wachsende Bakteriensuspension in einem Spektralphotometer bei einer Wellenlänge von 600 nm. Berechnen Sie die Bakteriendichte unter Verwendung des Umwandlungsfaktors von 0,1 OD 600 = 3 x 10 7 Bakterien pro ml. </li><li> Pipette aus genügend Bakterien für eine Multiplizität der Infektion (MOI) von 10: 1 in ein neues Zentrifugenröhrchen. Pelletieren bei 3.000 × g für 10 min und aspirieren die Flüssigkeit. In 50 ul Humanserum zu 450 ul RPMI1640. Skalieren Sie die Lautstärke auf die entsprechenden Werte für das Experiment. </li><li> Um die Bakterien zu opsonieren, das Pellet bei einer Dichte von 1 x 10 8 Bakterien pro 500 ul RPMI1640 , das 10% Humanserum. Lassen Sie die Mischung bei 37 ° C für 30 min inkubieren. Bestimmen Sie die THP-1-Zellkulturdichte, indem sie mit einem Hämocytometer gezählt und ein invertiertes microscope. </li><li> Pelletieren Sie die Zellen in sterilen Zentrifugenröhrchen bei 100 x g und 37 ° C für 10 min. Aspirieren den Überstand und die Zellen in RPMI unvollständig in einer Dichte von 1 Million Zellen pro ml. Hinzufügen Phorbol-12-Myristat-13-Acetat (PMA) zu einer 40 ng / ml Endkonzentration. Hinweis: Dies wird als Mix Differenzierung bezeichnet werden. </li><li> Kombinieren opsonisiertes M. tuberculosis mit THP-1 Differenzierungs Mischung bei einer MOI von 10: 1 und aliquotieren die Endmischung bei 100 &amp; mgr; l pro Vertiefung in einer 96-Well - Flachboden - weißen Platte. Regelmäßig rühren Sie die Mischung Einheitlichkeit zu gewährleisten. Ermöglicht die Differenzierung und die Infektion fortschreiten über Nacht bei 37 ° C in einem befeuchteten Inkubator mit 5% CO 2. </li><li> Waschen Sie die Vertiefungen zweimal mit 100 &amp; mgr; l RPMI jeder. Fügen Verbindungen auf die gewünschten Konzentrationen in RPMI verdünnt unvollständig und inkubiere 3 Tage lang. </li><li> Aspirieren das Medium aus den Vertiefungen. Zugeben von 50 &amp; mgr; l Luciferase-Assay-Reagens in jede Vertiefung. Abdichten der Platten mit transparent Klebeplatte Versiegelungen. Sie 5 min Inkubation bei 22 ° C und dann eine Anzeige in einem Luminometer bei 1 s pro Vertiefung erhalten. </li></ol> 4. Die Zytotoxizität Analyse unter Verwendung eines 3- (4,5-Dimethylthiazol-2-yl) -2,5-diphenyltetrazoliumbromid (MTT) Assay 14 <ol><li> Differenzieren THP-1-Zellen in RPMI unvollständig mit 40 ng / ml PMA in klaren 96-Loch-Platten, ergänzt. Achten Sie auf eine Zelldichte von 1 Million pro ml und aliquote 100 &amp; mgr; l pro Vertiefung. Ermöglicht die Differenzierung über Nacht bei 37 ° C in einem befeuchteten Inkubator mit 5% CO 2 fortschreiten. </li><li> Aspirieren das Medium aus den Vertiefungen und waschen Sie sie zweimal mit RPMI 1640. Verbindungen in RPMI zu den Vertiefungen unvollständig verdünnt hinzufügen. Inkubieren für 3 Tage. </li><li> Man löst 0,5 g MTT in 100 ml phosphatgepufferter Salzlösung (PBS), um eine Stammlösung von 5 mg machen / mL. Sterile Filter und Lagerung bei -20 ° C, vor Licht; ist es am besten diese Lösung frisch zu machen. </li><li> 2,5 h vor deme das Ende der Inkubationszeit 3-Tag, fügen Sie in jede Vertiefung 25 ul MTT-Lösung und die Inkubationszeit abzuschließen. </li><li> Bereiten 50% N, N-Dimethylformamid (DMF) durch Mischen von 250 ml DMF mit 250 ml deionisiertem Wasser. </li><li> Bereiten MTT-Extraktionspuffer, wie folgt: Man wiegt 100 g SDS in einer 500-ml-Flasche und 300 ml 50% DMF. Anwenden niedrige Hitze der SDS zu ermöglichen aufzulösen. 10 ml reiner Essigsäure und 12,5 ml 1 M HCl. Füllen bis zur 500 ml-Markierung mit 50% DMF; die endgültige Zusammensetzung des Extraktionspuffers beträgt 50% DMF, 20% SDS, 2,5% Essigsäure und 2,5% 1 M Salzsäure. </li><li> Am Ende der Behandlungszeit wird mit 100 &amp; mgr; l Extraktionspuffer (erwärmt auf 45 ° C keine Kristalle aufzulösen) in jede Vertiefung. Lassen Sie die Mischung über Nacht bei 37 inkubieren ° C in einem befeuchteten Inkubator mit 5% CO 2. Die Absorption bei 570 nm. HINWEIS: Der Zytotoxizitätstest wird am besten parallel durchgeführt mit einem intrazellularenular Bildschirm samt-Charge und das Alter der THP-1-Zellen. </li></ol> 5. In-Brühe Mit Aktivitätsanalyse einer Resazurin - Assay 3 <ol><li> Wächst M. tuberculosis in 7H9ADST zur mittleren log - Phase (~ 0,5 bis 0,8 OD 600). Verdünne die Kultur mit dem 7H9ADST bis 0,01 OD 600. Verdünne die Verbindungen in 7H9ADST die Testkonzentrationen und Aliquot 100 &amp; mgr; l der verdünnten Verbindung in jede Vertiefung auf 2x. </li><li> Übertragung von 100 &amp; mgr; l der verdünnten Bakteriensuspension in jede Vertiefung. Lassen Sie die Platten für 5 Tage bei 37 ° C in einem befeuchteten Inkubator inkubiert. Man löst 10 mg Resazurin in 100 ml deionisiertem Wasser und Sterilfilter. </li><li> In 30 ul Resazurin-Lösung und überwacht die Farbänderung nach 48 h; Bakterienwachstum wird durch eine Farbumwandlung von blau angezeigt rosa. ANMERKUNG: Eine quantitative Analyse kann auch durch das Messen entweder die Fluoreszenz bei 590 nm mit einer Anregung bei 530 durchgeführt werden - 560nm oder das Absorptionsvermögen bei 570 nm und 600 nm 15. </li></ol>

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The authors declare no competing financial interests for this work.

Verwendung eines menschlichen intrazellulären Infektionsmodell für M. tuberculosis Das Ziel dieser Studie war es, ein einfaches und kostengünstiges HTS - Verfahren zu erstellen. Tuberkulose ist ein Mensch durch die Infektion von Alveolarmakrophagen gekennzeichnet Krankheit , die durch M. tuberculosis. Aufgrund Fragen der biologischen Sicherheit, Forschung sowohl biologische Modelle des Bakteriums und die Wirtszellen beteiligt hat in der Vergangenheit verwendet worden. Allerdings hat es sich gezeigt ...

Mycobacterium tuberculosis, der Erreger der Tuberkulose (TB) ist eine führende Ursache von Morbidität und Mortalität weltweit. Arzneimittelempfindlichen TB ist eine behandelbare Krankheit, die für einen Zeitraum von 6 Monaten mehr Antibiotika erfordert. Trotz einer behandelbaren Krankheit zu sein, wurde TB Sterblichkeit schätzungsweise 1 1,5 Millionen im Jahr 2015 sein. In den letzten 10 Jahren wurden dort zunehmende Besorgnis über die Verbreitung von arzneimittelresistenten Tuberkulose M.. Mehrfach arzneimittelresistenter Tuberkulose (MDR-TB) als TB definiert, die mindestens Isoniazid (INH) und Rifampicin (RMP) beständig ist, und die meisten MDR-TB-Stämme sind auch resistent second-line TB Medikamente auszuwählen, wodurch Behandlungsoptionen Zu . Die Auswirkungen von Medikamentenresistenz eine größere Herausforderung für die Behandlung von Patienten schaffen-Koinfektion mit Human Immunodeficiency Virus (HIV); 400.000 Patienten starben weltweit von HIV-assoziierten TB im Jahr 2015 1. Enttäuschend, den Vereinigten Staaten Food and Drug AdministRation hat nur eine neues TB - Medikament gegen MDR-TB, Bedaquilin, in den letzten 40 Jahren 2 genehmigt. Die Fortschritte bei der Suche nach besseren und kürzeren TB-Therapien sind dringend erforderlich, um vorne zu bleiben im Kampf gegen TB und MDR-TB. Traditionell TB Arzneimittel Bildschirme sind unter in vitro - Wachstumsbedingungen in einem Wachstumsmedium durchgeführt, wobei Verbindungen zu einer wachsenden Kultur und ihre Wirksamkeit hinzugefügt werden die Mikroorganismen bei der Beseitigung der durch Zählen koloniebildenden Einheiten (CFU) auf einem festen Medium bestimmt. Als Keimzahlen arbeitsintensiv, zeitraubend und teuer werden verschiedene indirekte Methoden, um dieses Problem zu lindern entwickelt. Solche Verfahren umfassen die Lebensfähigkeit Alamar - Blau - Assay 3, die Bestimmung der Fluoreszenz 4 von grün fluoreszierendem Protein (GFP) oder Lumineszenz 5 von Luciferase-exprimierenden Bakterien, und die Schätzung der Gesamt Adenosintriphosphat (ATP) 6, 7. Typische TB wird durch eine Infektion mit M. tuberculosis der Lunge charakterisiert, in dem sich die Bakterien befinden , und im Inneren der Phagosomen von Alveolarmakrophagen 8 nachzubilden. Die einfache in-Brühe kann phänotypische Bildschirm extrazelluläre Erreger passen; jedoch in der historischen Perspektive getroffen Verbindungen gegen M. tuberculosis diese Methode oft identifiziert verwenden , nicht die Erwartungen bei der nachgeschalteten Validierungsschritten in Infektionsmodellen zu entsprechen . Wir schlagen vor, dass TB Medikament am besten in einem intrazellulären Wirtszelle Infektionsmodell durchgeführt wird. Dennoch besitzen die intrazelluläre Modelle viele technologische und biologische Barrieren für Hochdurchsatz-Screening (HTS) Entwicklung. Eine große Hürde ist die Komplexität des Infektionsprozesses, beispielhaft durch zahlreiche Schritte und die aufwendigen Entfernung von extrazellulären Bakterien, die durch in-zwischen dem Waschen. Eine zweite große Hürde ist die lange Zeit rederungen, als Wachstumserkennung erfolgt normalerweise durch Zählen CFU auf Kulturplatten, ist ein Prozess, vervollständigen über 3 Wochen dauert. Eine Lösung für CFU Zählungen ersetzt wurde durch automatisiertes Fluoreszenz-Mikroskopie in Kombination mit fluoreszierenden Bakterien bereitgestellt. Jedoch erfordert diese Lösung eine Erstausrüstung Investition, die für viele Forschungslabors außer Reichweite ist. Eine einfache, kostengünstige und krankheitsrelevanten HTS Verfahren würde die Drug Discovery-Prozess erheblich verbessern. In dieser Studie berichten wir über ein neues, modulares HTS - System , das auf der Bereitstellung eine schnelle und hochskalierbaren, noch wirtschaftlich, Assay geeignet zur Bestimmung der Aktivität von Verbindungen gegen intrazelluläre M. tuberculosis gerichtet ist. Dieses System besteht aus drei Modulen: (i) intrazelluläre, (ii) die Zytotoxizität und (iii) in-Broth-Assays. Das kombinierte Endergebnis liefert eine umfassende Beschreibung der Verbindung Eigenschaften, mit zusätzlichen Informationen in Bezug auf die mögliche Wirkungsweise. diese screening System in mehreren Projekten mit verschiedenen Substanzbibliotheken verwendet worden ist, die Wirkungsweise zielen, einschließlich der Analyse von Arzneimittel Synergie 9, -secreted die Stimulation von autophagy 10 und die Hemmung von M. tuberculosis Virulenzfaktor (nicht veröffentlicht). Verbindungen unbekannter Wirkungsweise haben auch 11 untersucht worden. Eine modifizierte Version dieses Verfahrens wurde auch durch unsere Industriepartner als primäre Screening - Verfahren zur Identifizierung neuer Verbindungen gegen intrazelluläre M. tuberculosis 11 angenommen.

<table><tbody><tr><td>RPMI 1640</td><td>Sigma-Aldrich</td><td>R5886</td><td></td></tr><tr><td>L-glutamine</td><td>Sigma-Aldrich</td><td>G7513</td><td></td></tr><tr><td>Fetal bovine serum (FBS)</td><td>Thermo Fisher Scientific</td><td>12483020</td><td></td></tr><tr><td>Middlebrook 7H9</td><td>Becton, Dickinson and Company</td><td>271210</td><td></td></tr><tr><td>Tween80</td><td>Fisher Scientific</td><td>T164</td><td></td></tr><tr><td>Albumin, Bovine pH7</td><td>Affymetrix</td><td>10857</td><td></td></tr><tr><td>Dextrose</td><td>Fisher Scientific</td><td>BP350</td><td></td></tr><tr><td>Sodium Chloride</td><td>Fisher Scientific</td><td>BP358</td><td></td></tr><tr><td>kanamycin sulfate</td><td>Fisher Scientific</td><td>BP906</td><td></td></tr><tr><td>PMA</td><td>Sigma-Aldrich</td><td>P8139</td><td></td></tr><tr><td>MTT</td><td>Sigma-Aldrich</td><td>M2128</td><td></td></tr><tr><td>&lt;em&gt;N,N&lt;/em&gt;-Dimethylformamide (DMF)</td><td>Fisher Scientific</td><td>D131</td><td></td></tr><tr><td>1 M Hydrocholoric acid (HCl)</td><td>Fisher Scientific</td><td>351279212</td><td></td></tr><tr><td>Acetic acid</td><td>Fisher Scientific</td><td>351269</td><td></td></tr><tr><td>SDS</td><td>Fisher Scientific</td><td>BP166</td><td></td></tr><tr><td>Resazurin</td><td>Alfa Aesar</td><td>B21187</td><td></td></tr><tr><td>DMSO</td><td>Sigma-Aldrich</td><td>D5879</td><td></td></tr><tr><td>Glycerol</td><td>Fisher Scientific</td><td>BP229</td><td></td></tr><tr><td>THP-1</td><td>American Type Culture Collection</td><td>TIB-202</td><td></td></tr><tr><td>&lt;em&gt;M. tuberculosis&lt;/em&gt; H37Rv</td><td></td><td></td><td></td></tr><tr><td>96-well flat bottom white plate</td><td>Corning</td><td>3917</td><td></td></tr><tr><td>95-well flat bottom clear plate</td><td>Corning</td><td>3595</td><td></td></tr><tr><td>Transparent plate sealer</td><td>Thermo Fisher Scientific</td><td>AB-0580</td><td></td></tr><tr><td>Spectrophotometer</td><td>Thermo Fisher Scientific</td><td>Biomate 3</td><td></td></tr><tr><td>Microplate spectrophotometer</td><td>Biotek</td><td>Epoch</td><td></td></tr><tr><td>luminometer</td><td>Applied Biosystems</td><td>Tropix TR717</td><td></td></tr></tbody></table>

system for efficacy and cytotoxicity screening of inhibitors targeting intracellular mycobacterium tuberculosis

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a leading cause of morbidity and mortality worldwide. With the increased spread of multi drug-resistant TB (MDR-TB), there is a real urgency to develop new therapeutic strategies against M. tuberculosis infections. Traditionally, compounds are evaluated based on their antibacterial activity under in vitro growth conditions in broth; however, results are often misleading for intracellular pathogens like M. tuberculosis since in-broth phenotypic screening conditions are significantly different from the actual disease conditions within the human body. Screening for inhibitors that work inside macrophages has been traditionally difficult due to the complexity, variability in infection, and slow replication rate of M. tuberculosis. In this study, we report a new approach to rapidly assess the effectiveness of compounds on the viability of M. tuberculosis in a macrophage infection model. Using a combination of a cytotoxicity assay and an in-broth M. tuberculosis viability assay, we were able to create a screening system that generates a comprehensive analysis of compounds of interest. This system is capable of producing quantitative data at a low cost that is within reach of most labs and yet is highly scalable to fit large industrial settings.

Hochdurchsatz - Screening unter Verwendung von intrazellulären M. tuberculosis exprimieren das Luciferasegen 2A und Tabelle 1 enthalten die Rohdaten von dem Luminometer gesammelt, in relativen Lumineszenz - Einheiten ausgedrückt (RLU), zeigen die Wirkung einer Erhöhung der Konzentration des Arzneimittels TB Rifampicin auf M. tuberculosis innerhalb THP-1 - Zellen. 2A</...

Watch this Scientific Journal Video about System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis at JoVE.com

System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis

Wir haben für die Entdeckung neuer Verbindungen gegen Mycobacterium tuberculosis ein modulares Hochdurchsatz - Screening - System entwickelt, und die intrazelluläre Targeting-Brühe in Bakterien sowie Zytotoxizität gegen die Säuger - Wirtszelle wächst.

System zur Wirksamkeit und Zytotoxizität Screening von Inhibitoren Targeting intrazellulärer<em&gt; Mycobacterium tuberculosis</em

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a leading cause of morbidity and mortality worldwide. With the increased spread ...

system-for-efficacy-cytotoxicity-screening-inhibitors-targeting

Universidad de Cartagena UDEC

Research

JoVE Journal

Immunology and Infection

System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis

8.5K Aufrufe.  University of British Columbia.  Wir haben für die Entdeckung neuer Verbindungen gegen Mycobacterium tuberculosis ein modulares Hochdurchsatz - Screening - System entwickelt, und die intrazelluläre Targeting-Brühe in Bakterien sowie Zytotoxizität gegen die Säuger - Wirtszelle wächst. 

Serie: System for Efficacy and Cytotoxicity Screening of Inhibitors Targeting Intracellular Mycobacterium tuberculosis

Sample Preparation of Mycobacterium tuberculosis Extracts for Nuclear Magnetic Resonance Metabolomic Studies

Mycobacterium tuberculosis is a major cause of mortality in human beings on a global scale. The emergence of both multi- (MDR) and extensively-(XDR) drug-resistant strains threatens to derail current disease control efforts. Thus, there is an urgent need to develop drugs and vaccines that are more effective than those currently available. The genome of M. tuberculosis has been known for more than 10 years, yet there are important gaps in our knowledge of gene function and essentiality. Many studies have since used gene expression analysis at both the transcriptomic and proteomic levels to determine the effects of drugs, oxidants, and growth conditions on the global patterns of gene expression. Ultimately, the final response of these changes is reflected in the metabolic composition of the bacterium including a few thousand small molecular weight chemicals. Comparing the metabolic profiles of wild type and mutant strains, either untreated or treated with a particular drug, can effectively allow target identification and may lead to the development of novel inhibitors with anti-tubercular activity. Likewise, the effects of two or more conditions on the metabolome can also be assessed. Nuclear magnetic resonance (NMR) is a powerful technology that is used to identify and quantify metabolic intermediates. In this protocol, procedures for the preparation of M. tuberculosis cell extracts for NMR metabolomic analysis are described. Cell cultures are grown under appropriate conditions and required Biosafety Level 3 containment,1 harvested, and subjected to mechanical lysis while maintaining cold temperatures to maximize preservation of metabolites. Cell lysates are recovered, filtered sterilized, and stored at ultra-low temperatures. Aliquots from these cell extracts are plated on Middlebrook 7H9 agar for colony-forming units to verify absence of viable cells. Upon two months of incubation at 37 &deg;C, if no viable colonies are observed, samples are removed from the containment facility for downstream processing. Extracts are lyophilized, resuspended in deuterated buffer and injected in the NMR instrument, capturing spectroscopic data that is then subjected to statistical analysis. The procedures described can be applied for both one-dimensional (1D) 1H NMR and two-dimensional (2D) 1H-13C NMR analyses. This methodology provides more reliable small molecular weight metabolite identification and more reliable and sensitive quantitative analyses of cell extract metabolic compositions than chromatographic methods. Variations of the procedure described following the cell lysis step can also be adapted for parallel proteomic analysis.

Sample Preparation of Mycobacterium tuberculosis Extracts for Nuclear Magnetic Resonance Metabolomic Studies

The metabolomic profile of Mycobacterium tuberculosis is determined after growth in broth cultures. Conditions can be varied to test the effects of nutritional supplements, oxidants, and anti-tuberculosis agents on the metabolic profile of this microorganism. Procedure for extract preparation is applicable for both 1D 1H and 2D 1H-13C NMR analyses.

Probenvorbereitung von<em&gt; Mycobacterium tuberculosis</em&gt; Extrakte für Nuclear Magnetic Resonance Metabolomic Studies

Mycobacterium tuberculosis is a major cause of mortality in human beings on a global scale. The emergence of both multi- (MDR) and extensively-(XDR) ...

Forschung

Immunologie und Infektion

A Microscopic Phenotypic Assay for the Quantification of Intracellular Mycobacteria Adapted for High-throughput/High-content Screening

Despite the availability of therapy and vaccine, tuberculosis (TB) remains one of the most deadly and widespread bacterial infections in the world. Since several decades, the sudden burst of multi- and extensively-drug resistant strains is a serious threat for the control of tuberculosis. Therefore, it is essential to identify new targets and pathways critical for the causative agent of the tuberculosis, Mycobacterium tuberculosis (Mtb) and to search for novel chemicals that could become TB drugs. One approach is to set&#160;up methods suitable for the genetic and chemical screens of large scale libraries enabling the search of a needle in a haystack. To this end, we developed a phenotypic assay relying on the detection of fluorescently labeled Mtb within fluorescently labeled host&#160;cells using automated confocal microscopy. This in vitro assay allows an image based quantification of the colonization process of Mtb&#160;into the host and was optimized for the 384-well microplate format, which is proper for screens of siRNA-, chemical compound- or Mtb mutant-libraries. The images are then processed for multiparametric analysis, which provides read&#160;out inferring on the pathogenesis of Mtb&#160;within host cells.

Here, we describe a phenotypic assay applicable to the High-throughput/High-content screens of small-interfering synthetic RNA (siRNA), chemical compound, and Mycobacterium tuberculosis mutant libraries. This method relies on the detection of fluorescently labeled Mycobacterium tuberculosis within fluorescently labeled host&#160;cell using automated confocal microscopy.

Ein mikroskopischer phänotypischer Assay zur Quantifizierung intrazellulärer Mykobakterien angepasst für High-Throughput/High-Content Screening

Despite the availability of therapy and vaccine, tuberculosis (TB) remains one of the most deadly and widespread bacterial infections in the world. Since ...

Visualization of the Charcoal Agar Resazurin Assay for Semi-quantitative, Medium-throughput Enumeration of Mycobacteria

There is an urgent need to discover and progress anti-infectives that shorten the duration of tuberculosis (TB) treatment. Mycobacterium tuberculosis, the etiological agent of TB, is refractory to rapid and lasting chemotherapy due to the presence of bacilli exhibiting phenotypic drug resistance. The charcoal agar resazurin assay (CARA) was developed as a tool to characterize active molecules discovered by high-throughput screening campaigns against replicating and non-replicating M. tuberculosis. Inclusion of activated charcoal in bacteriologic agar medium helps mitigate the impact of compound carry-over, and eliminates the requirement to pre-dilute cells prior to spotting on CARA microplates. After a 7-10 day incubation period at 37 &#176;C, the reduction of resazurin by mycobacterial microcolonies growing on the surface of CARA microplate wells permits semi-quantitative assessment of bacterial numbers via fluorometry. The CARA detects approximately a 2-3 log10 difference in bacterial numbers and predicts a minimal bactericidal concentration leading to &#8805;99% bacterial kill (MBC&#8805;99). The CARA helps determine whether a molecule is active on bacilli that are replicating, non-replicating, or both. Pilot experiments using the CARA facilitate the identification of which concentration of test agent and time of compound exposure require further evaluation by colony forming unit (CFU) assays. In addition, the CARA can predict if replicating actives are bactericidal or bacteriostatic.

The charcoal agar resazurin assay (CARA) is a semi-quantitative, medium-throughput method to assess activity of test agents against mycobacteria that are replicating, non-replicating, or both. The CARA permits rapid evaluation of time- and concentration-dependent activity and identifies parameters to pursue by colony forming unit (CFU) assays.

Visualisierung des Charcoal Agar Resazurin-Assay für Semi-quantitative, Mitteldurch Auszählung von Mykobakterien

There is an urgent need to discover and progress anti-infectives that shorten the duration of tuberculosis (TB) treatment. Mycobacterium tuberculosis, the ...

High Throughput, Real-time, Dual-readout Testing of Intracellular Antimicrobial Activity and Eukaryotic Cell Cytotoxicity

Traditional measures of intracellular antimicrobial activity and eukaryotic cell cytotoxicity rely on endpoint assays. Such endpoint assays require several additional experimental steps prior to readout, such as cell lysis, colony forming unit determination, or reagent addition. When performing thousands of assays, for example, during high-throughput screening, the downstream effort required for these types of assays is considerable. Therefore, to facilitate high-throughput antimicrobial discovery, we developed a real-time assay to simultaneously identify inhibitors of intracellular bacterial growth and assess eukaryotic cell cytotoxicity. Specifically, real-time intracellular bacterial growth detection was enabled by marking bacterial screening strains with either a bacterial lux operon (1st generation assay) or fluorescent protein reporters (2nd generation, orthogonal assay). A non-toxic, cell membrane-impermeant, nucleic acid-binding dye was also added during initial infection of macrophages. These dyes are excluded from viable cells. However, non-viable host cells lose membrane integrity permitting entry and fluorescent labeling of nuclear DNA (deoxyribonucleic acid). Notably, DNA binding is associated with a large increase in fluorescent quantum yield that provides a solution-based readout of host cell death. We have used this combined assay to perform a high-throughput screen in microplate format, and to assess intracellular growth and cytotoxicity by microscopy. Notably, antimicrobials may demonstrate synergy in which the combined effect of two or more antimicrobials when applied together is greater than when applied separately. Testing for in vitro synergy against intracellular pathogens is normally a prodigious task as combinatorial permutations of antibiotics at different concentrations must be assessed. However, we found that our real-time assay combined with automated, digital dispensing technology permitted facile synergy testing. Using these approaches, we were able to systematically survey action of a large number of antimicrobials alone and in combination against the intracellular pathogen, Legionella pneumophila.

A high throughput, real-time assay was developed to simultaneously identify (1) eukaryotic cell-penetrant antimicrobials targeting an intracellular bacterial pathogen, and (2) assess eukaryotic cell cytotoxicity. A variation on the same technology was thereafter combined with digital dispensing technology to enable facile, high-resolution, dose-response, and two- and three-dimensional synergy studies.

Hoher Durchsatz, Echtzeit, Doppel-Ausleseprüfung intrazellulärer antimikrobieller Aktivität und eukaryotischen Zelle Zytotoxizität

Traditional measures of intracellular antimicrobial activity and eukaryotic cell cytotoxicity rely on endpoint assays. Such endpoint assays require ...

A High-throughput Compatible Assay to Evaluate Drug Efficacy against Macrophage Passaged Mycobacterium tuberculosis

The early drug development process for anti-tuberculosis drugs is hindered by the inefficient translation of compounds with in vitro activity to effectiveness in the clinical setting. This is likely due to a lack of consideration for the physiologically relevant cellular penetration barriers that exist in the infected host. We recently established an alternative infection model that generates large macrophage aggregate structures containing densely packed M. tuberculosis (Mtb) at its core, which was suitable for drug susceptibility testing. This infection model is inexpensive, rapid, and most importantly BSL-2 compatible. Here, we describe the experimental procedures to generate Mtb/macrophage aggregate structures that would produce macrophage-passaged Mtb for drug susceptibility testing. In particular, we demonstrate how this infection system could be directly adapted to the 96-well plate format showing throughput capability for the screening of compound libraries against Mtb. Overall, this assay is a valuable addition to the currently available Mtb drug discovery toolbox due to its simplicity, cost effectiveness, and scalability.

A High-throughput Compatible Assay to Evaluate Drug Efficacy against Macrophage Passaged Mycobacterium tuberculosis

New models and assays that would improve the early drug development process for next-generation anti-tuberculosis drugs are highly desirable. Here, we describe a quick, inexpensive, and BSL-2 compatible assay to evaluate drug efficacy against Mycobacterium tuberculosis that can be easily adapted for high-throughput screening.

Ein Hochdurchsatz-Assay unterstützte Wirksamkeit von Medikamenten gegen Makrophagen agierten zur Bewertung<em&gt; Mycobacterium tuberculosis</em

The early drug development process for anti-tuberculosis drugs is hindered by the inefficient translation of compounds with in vitro activity to ...

An Automated Culture System for Use in Preclinical Testing of Host-Directed Therapies for Tuberculosis

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), was the most significant infectious disease killer globally until the advent of COVID-19. Mtb has evolved to persist in its intracellular environment, evade host defenses, and has developed resistance to many anti-tubercular drugs. One approach to solving resistance is identifying existing&#160;approved drugs that will boost the host immune response to Mtb. These drugs could then be repurposed as adjunctive host-directed therapies (HDT) to shorten treatment time and help overcome antibiotic resistance.
Quantification of intracellular Mtb growth in macrophages is a crucial aspect of assessing potential HDT. The gold standard for measuring Mtb growth is counting colony-forming units (CFU) on agar plates. This is a slow, labor-intensive assay that does not lend itself to rapid screening of drugs. In this protocol, an automated, broth-based culture system, which is more commonly used to detect Mtb in clinical specimens, has been adapted for preclinical screening of host-directed therapies. The capacity of the liquid culture assay system to investigate intracellular Mtb growth in macrophages treated with HDT was evaluated. The HDTs tested for their ability to inhibit Mtb growth were all-trans Retinoic acid (AtRA), both in solution and encapsulated in poly(lactic-co-glycolic acid) (PLGA) microparticles and the combination of interferon-gamma and linezolid. The advantages of this automated liquid culture-based technique over the CFU method include simplicity of setup, less labor-intensive preparation, and faster time to results (5-12 days compared to 21 days or more for agar plates).

Rapid and efficient quantification of intracellular M. tuberculosis growth is crucial for pursuing improved therapies against tuberculosis (TB). This protocol describes a broth-based colorimetric detection assay using an automated liquid culture system to quantify Mtb growth in macrophages treated with candidate host-directed therapies.

Ein automatisiertes Kultursystem zur präklinischen Erprobung wirtsgerichteter Therapien für Tuberkulose

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), was the most significant infectious disease killer globally until the advent ...

<meta charset="utf8"></head><body>Hochdurchsatz-Screening-Assay für Mycobacterium abscessus mit Dual-Reportern

Assay Development for High-Throughput Drug Screening Against Mycobacteria

Mycobacterium abscessus (Mab) infections are challenging to treat due to high intrinsic drug resistance, comparable to multidrug-resistant tuberculosis. Treatments are extremely ineffective and based on a multi-drug regimen, resulting in low patient compliance. Consequently, the scientific community is urged to identify new and effective drugs to treat these infections. One of the strategies employed to this end is drug repurposing - the process of identifying new therapeutic opportunities for existing drugs in the market, circumventing the time required to establish pharmacokinetic and safety profiles of new drugs. With most studies on drug development against Mab relying on traditional and time-consuming methods, an assay for high-throughput drug screening was developed against mycobacteria using an in house developed double-reporter strain of Mab. Using liquid-handling robotics, automated microscopy, and analysis, alongside in house developed double reporter strains, bacterial viability can be rapidly measured using two different readouts, luminescence and fluorescence, without adding reagents or performing any extra steps. This reduces time and variability between assays, a major advantage for high-throughput screenings. The described protocol was validated by screening a library of 1280 compounds. The obtained results were corroborated by the literature, with efficient detection of active compounds. Thus, this work fulfilled the aim of supplying the field with a new tool to help fight this extremely drug-resistant bacteria.

<meta charset="utf8"></head><body>Autor im Rampenlicht: Skalierbares Wirkstoff-Screening-Protokoll für die effiziente Entdeckung von M. abscessus-Behandlungen

This study developed an assay for high-throughput screening against Mycobacterium abscessus with a&#160;recently created double reporter strain, using fluorescence and luminescence to assess bacterial viability quickly. This protocol will be relevant for researchers aiming to screen new drugs against this drug-resistant bacteria.

Assay-Entwicklung für das Hochdurchsatz-Wirkstoffscreening gegen Mykobakterien

Mycobacterium abscessus (Mab) infections are challenging to treat due to high intrinsic drug resistance, comparable to multidrug-resistant tuberculosis. ...

Beschleunigung der Tuberkulosebestimmung mit der Mikro-KBE-Methode

Micro-Colony Forming Unit Assay for Efficacy Evaluation of Vaccines Against Tuberculosis

Tuberculosis (TB), the leading cause of death worldwide by an infectious agent, killed 1.6 million people in 2022, only being surpassed by COVID-19 during the 2019-2021 pandemic. The disease is caused by the bacterium Mycobacterium tuberculosis (M.tb). The Mycobacterium bovis strain Bacillus Calmette-Gu&#233;rin (BCG), the only TB vaccine, is the oldest licensed vaccine in the world, still in use. Currently, there are 12 vaccines in clinical trials and dozens of vaccines under pre-clinical development. The method of choice used to assess the efficacy of TB vaccines in pre-clinical studies is the enumeration of bacterial colonies by the colony-forming units (CFU) assay. This time-consuming assay takes 4 to 6 weeks to conclude, requires substantial laboratory and incubator space, has high reagent costs, and is prone to contamination. Here we describe an optimized method for colony enumeration, the micro-CFU (mCFU), that offers a simple and rapid solution to analyze M.tb vaccine efficacy results. The mCFU assay requires tenfold fewer reagents, reduces the incubation period threefold, taking 1 to 2 weeks to conclude, reduces lab space and reagent cost, and minimizes the health and safety risks associated with working with large numbers of M.tb. Moreover, to evaluate the efficacy of a TB vaccine, samples may be obtained from a variety of sources, including tissues from vaccinated animals infected with Mycobacteria. We also describe an optimized method to produce a unicellular, uniform, and high-quality mycobacterial culture for infection studies. Finally, we propose that these methods should be universally adopted for pre-clinical studies of vaccine efficacy determination, ultimately leading to time reduction in the development of vaccines against TB.

Autor im Rampenlicht: Optimierung der KBE-Bestimmung für eine effiziente Bewertung der Wirksamkeit von TB-Impfstoffen und der Analyse der Antigenpräsentation 

The determination of colony-forming units (CFU) is the gold-standard technique for quantifying bacteria, including Mycobacterium tuberculosis which can take weeks to form visible colonies. Here we describe a micro-CFU for CFU determination with increased time efficiency, reduced lab space and reagent cost, and scalability to medium and high throughput experiments.

Mikrokoloniebildender Unit-Assay zur Wirksamkeitsbewertung von Impfstoffen gegen Tuberkulose

Tuberculosis (TB), the leading cause of death worldwide by an infectious agent, killed 1.6 million people in 2022, only being surpassed by COVID-19 during ...

System zur Wirksamkeit und Zytotoxizität Screening von Inhibitoren Targeting intrazellulärer

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