Deseamos agradecer a Johnson &amp; Johnson, TB Alliance, Astra Zeneca, Rib-X y Trius Therapeutics por proporcionar bedaquiline, PA-824 (pretomanida), AZD5847, radezolid y tedizolid, respectivamente. Brendan Prideaux, Matthew Zimmerman, Stephen Juzwin, Emma Rey-Jurado, Nancy Ruel, Leyan Li y Danielle Weiner apoyaron el análisis MALDI, los métodos bioanalíticos, la preparación del sustituto del caseo, la síntesis química y el aislamiento del caseo de conejo. Este trabajo se llevó a cabo con fondos de la Fundación Bill y Melinda Gates, el premio # OPP1044966 y OPP1024050 a V. Dartois, la Subvención de Instrumentación Compartida NIH S10OD018072, así como el financiamiento conjunto de la Fundación Bill y Melinda Gates y Wellcome Trust for A Centre of Excellence Para la optimización del plomo para las enfermedades del mundo en vías de desarrollo a P. Wyatt.

Todos los estudios con animales se llevaron a cabo de acuerdo con la Guía para el Cuidado y Uso de Animales de Laboratorio de los Institutos Nacionales de Salud, con la aprobación del Comité Institucional Animal Cuidado y Uso del NIAID (NIH), Bethesda, MD. Se realizaron todos los estudios con M. tuberculosis en un laboratorio con nivel de bioseguridad de contención 3 (BSL-3). 1. Conejo Modelo de infección y caseosa Colección <ol><li> Infect Nueva Zelanda conejos blancos con M. tuberculosis usando un sistema de exposición a aerosol sólo para la nariz como se describió anteriormente. 12, 13 permitir que la infección progrese durante 12-16 semanas. Sedate los conejos con 35 mg / kg de ketamina y 5 mg / kg de xilazina por vía intramuscular, la eutanasia a los conejos con 0,22 ml / kg de pentobarbital de sodio de sodio y fenitoína por vía intravenosa y proceder con la necropsias. </li><li> El uso de pinzas y bisturí, retire los pulmones de la ca pechoVidad De cada lóbulo pulmonar, diseccionar cavidades individuales y grandes granulomas necróticos con un bisturí. Raspe con cuidado el caseum de las paredes de la cavidad y del granuloma. Pesar, registrar y almacenar las muestras en tubos tapados con tornillos de 2 mL a -20 ° C hasta que estén listos para su uso. </li><li> Irradiar gamma las muestras de caseo infeccioso a 3 MegaRad en hielo seco para hacerlas no infecciosas y seguras para su uso en un laboratorio BSL-2. </li></ol> 2. Generación in vitro de sustituto de caseo a partir de células THP-1 <ol><li> Cultivo de monocitos THP-1 en medio RPMI 1640 (L-glutamina 2 mM y suero fetal bovino al 10%) en matraces de cultivo celular T175 (80 ml / matraz). Incubar los matraces en una atmósfera de CO2 al 5% a 37 ° C durante 3-4 días. </li><li> Centrifugar el cultivo de un matraz T175 en dos tubos cónicos de 50 ml a 150 xg durante 5 min. Desechar el sobrenadante y suspender el sedimento en 10 ml de medio RPMI 1640. </li><li> Pipetear 5 μL de este cultivo en un tubo de 1,5 ml que contenga 45 μl de tRypan azul Mezcle bien pipeteando. Transferir 10 μL a un hemocitómetro y contar el número de monocitos THP-1 viables (sin tinción) utilizando un microscopio óptico (aumento de 10X). Calcular el número de células viables por ml del cultivo. Diluir con medio RPMI hasta la densidad final de 1,25 x 106 células / ml. </li><li> Cargar 40 mL del cultivo en una placa de cultivo celular grande (50 x 106 células / placa). Añadir 40 μL de 100 μM de PMA (forbol 12-miristato13-acetato preparado en etanol) y permitir que las células se adhieran durante la noche en la incubadora. NOTA: La concentración final de PMA es 100 nM. </li><li> Diluir ácido oleico puro (OA) (0,89 g / ml) en etanol hasta la concentración de 0,1 M ( es decir, 31,7 μl de OA en 968,3 μl de etanol). Diluir esta solución en medio RMPI precalentado fresco a una concentración de 10 mM. Diluir esta suspensión de OA a 0,4 mM (concentración final de trabajo) en medio RPMI precalentado a 37ºC. </li><li> Eliminar los medios existentes y losDe las placas de cultivo celular y añadir suavemente 40 ml de OA 0,4 mM a los macrófagos THP-1 (THP-M). Incubar a 37 ° C en la incubadora durante la noche. </li><li> Utilice un microscopio óptico con una ampliación de 40x para confirmar visualmente la presencia de numerosas inclusiones de cuerpo lipídico en cada THP-M. Eliminar todo el medio RPMI de las placas de cultivo celular y lavar suavemente las células adherentes dos veces con solución salina tamponada con fosfato (PBS) usando una pipeta serológica de 50 ml. NOTA: Los cuerpos lipídicos aparecen como estructuras pequeñas, claras y esféricas en el citoplasma del THP-M. </li><li> Añadir 40 mL de ácido etilendiaminotetraacético 5 mM (EDTA) en PBS a cada placa. Incubar durante 15 minutos a 37 ° C. </li><li> Desmonte los macrófagos espumosos (FM) pipeteando repetidamente hacia arriba y hacia abajo sobre la superficie de la placa entera usando una pipeta serológica de 10 ml. Transferir la suspensión celular a un tubo cónico de 50 ml y centrifugar a 150 xg durante 5 min. </li><li> Resuspender el sedimento celular en 10 ml de PBS (tercer lavado con PBS) aNd a un tubo cónico de 15 mL previamente pesado. Girar de nuevo a 150 xg durante 5 min. Aspirar cuidadosamente el sobrenadante con una pipeta serológica y desecharla. </li><li> Sujeción de los gránulos de FM a 3 ciclos de congelación-descongelación para lisar las células e incubar a 75 ° C durante 20-30 min para desnaturalizar las proteínas en la matriz. Guarde los gránulos a -20 ° C hasta que estén listos para su uso. </li></ol> 3. Ensayo de Diálisis de Equilibrio Rápido (RED) <ol><li> Preparar soluciones madre 10 mM de todos los compuestos de ensayo en dimetilsulfóxido (DMSO). Diluir a 500 μM de soluciones de trabajo en DMSO antes de cada ensayo. </li><li> Pesar el tubo que contiene la pastilla de caseo sustituto. Reste el peso del tubo vacío para obtener el peso del gránulo solo. Añadir 2-3 perlas de metal por tubo y, utilizando un homogeneizador de tejidos a 1200 golpes / minuto durante 1 minuto, romper el caseo o la matriz sustituta en PBS (1: 9 w / v) para conseguir 10x de suspensión diluida de cada matriz. </li><li> Spike 6.5 μL de los 500ΜM del compuesto de ensayo en 643,5 μl del homogeneizado para alcanzar la concentración final de 5 μM (≤1% de DMSO) y vórtice. </li><li> Coloque los insertos ROJOS en la placa base. Añadir 200 μl de la matriz de droga en la cámara del donante (anillo rojo) de cada inserto ROJO y 350 μl de PBS en cada cámara receptora. Prepare 3 insertos para cada compuesto de ensayo (muestras triplicadas). Sellar la placa con un sello de placa adhesiva e incubar a 37 ° C en el termomixer a 200 rpm (1 xg) durante 4 h. </li><li> Después de la incubación, mezcle suavemente el contenido de las cámaras del donante y del receptor pipeteando arriba y abajo 2-3 veces. Pipetear 20 μL de alícuotas de homogeneizado de las cámaras donadoras y añadir 20 μL de PBS limpio en un tubo de 1,5 ml (1: 1). De forma similar, se pipetean alícuotas de 20 μl de muestras de PBS de las cámaras receptoras y se añaden a 20 μl de homogeneizado limpio (combinación de matriz). 8 NOTA: La concordancia de matriz elimina la need para 2 curvas de calibración separadas (en homogeneizado y PBS) que se hizo para el análisis cuantitativo. El contenido de la cámara donante pueden sedimentar con el tiempo. Mezclar suavemente el contenido pipeteando antes de retirar alícuotas. </li></ol> 4. CL-EM Cuantificación y Análisis de Datos <ol><li> Añadir 160! L de 1: 1 de metanol: acetonitrilo que contiene 500 ng / ml de diclofenaco o 10 ng / ml de verapamil (patrón interno) a cada tubo y vórtice para precipitar las proteínas. Centrifugar a 10.000 xg durante 5 min para sedimentar el precipitado sobrenadantes y transferencia en placas de 96 pocillos de pocillos profundos para el análisis de líquido espectrometría de masas-cromatografía (LCMS). 7 </li><li> Construir curvas de calibración de 1-1.000 nM para cada compuesto de ensayo mientras se mantiene la misma composición de la matriz que las muestras anteriormente. Cuantificar la concentración de compuesto de ensayo en las muestras de las cámaras donante y receptora utilizando un método LC-MS. </li><li> Calcular la fracción no unida (f u) oF el fármaco en matriz diluida utilizando la ecuación 1. Calcular el f u en matriz sin diluir usando la ecuación 2 ( D = factor de dilución de 10). 14 <img alt="Ecuación 1" src="/files/ftp_upload/55559/55559eq1.jpg" /> <img alt="Ecuación 2" src="/files/ftp_upload/55559/55559eq2.jpg" /></li><li> Compruebe la recuperación (balance de masa) de cada compuesto usando la ecuación 3 para identificar compuestos con estabilidad / metabolismo / problemas de unión no específicos. NOTA: La recuperación típicamente cae entre 70% y 130%. 15 <img alt="Ecuación 3" src="/files/ftp_upload/55559/55559eq3.jpg" /></li></ol>

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lesiones necróticas pulmonares y cavidades en los pacientes de tuberculosis infectados contienen subpoblaciones de bacterias que son recalcitrantes al tratamiento farmacológico. Los núcleos caseosos de estas estructuras son particularmente responsable de albergar estos persisters en un entorno extracelular. 16 distribución favorable de agentes antibacterianos en estos lugares remotos se cree que es un determinante importante de la eficacia del fármaco tuberculosis. Antes de la validación de...

El tratamiento de la tuberculosis pulmonar requiere una distribución eficaz de fármacos en diferentes tipos de lesiones. Las lesiones necróticas y las cavidades contienen centros caseosos que albergan subpoblaciones de bacterias tolerantes a los fármacos o &quot;persistentes&quot;. 1 , 2 La enfermedad cavitaria se asocia con tasas de curación inferiores y mal pronóstico. 3 , 4 Estudios previos han demostrado, usando técnicas cuantitativas y de imágenes, que la capacidad de penetrar el caseo varía significativamente de una clase de fármaco a otra. 5 , 6 Estos métodos, sin embargo, requieren el uso de modelos de infección animal que son lentos y tediosos. Se diseñó un ensayo in vitro que mide la unión del fármaco al caseo ex vivo . Se encontró que esta unión se correlacionaba inversamente con la penetración del fármaco en granulomas caseosos y, por lo tanto, esUtilizado como herramienta predictiva. 7 La diálisis de equilibrio se considera como el método estándar de oro para los estudios de unión a proteínas plasmáticas. El dispositivo de diálisis de equilibrio rápido (RED) proporciona un sistema rápido, fácil de usar y fiable para realizar tales ensayos. 8 El dispositivo se compone de dos componentes: insertos de un solo uso y desechables compuestos de 2 cámaras separadas por un cilindro vertical de membrana semipermeable; Y placas de base reutilizables que pueden contener hasta 48 insertos a la vez. La membrana de diálisis tiene un corte de peso molecular de 8 kDa (MWCO) que es ideal para estudios de unión de fármacos-macromoléculas. La alta relación superficie / volumen del compartimento de membrana permite una diálisis rápida y equilibrio. Tanto los insertos como la placa de base han sido validados para una unión no específica específica. La combinación del dispositivo RED con técnicas bioanalíticas proporciona estimaciones precisas de las fracciones no unidas de fármacos en pLasma 8 , 9 Aunque originalmente se diseñó para medir la unión a proteínas plasmáticas, el dispositivo RED se ha utilizado en varios estudios de unión de tejidos utilizando homogenados. 10 , 11 En este protocolo, medimos la unión del fármaco al caseo, los residuos necróticos escindidos de las lesiones necróticas y cavidades de los conejos infectados con tuberculosis. La naturaleza acelular y no vascular del material caseoso hace que sea fácil de homogeneizar en una suspensión homogénea que sea compatible con el ensayo. Dado que el caseum es tedioso para producir y difícil de conseguir, el protocolo también ha sido validado para su uso con una matriz sustituta que se prepara a partir de macrófagos espumosos. Los macrófagos derivados de monocitos THP-1 son inducidos con ácido oleico para acumular múltiples cuerpos lipídicos que les dan su aspecto &quot;espumoso&quot;. Estas células cargadas de lípidos se cosechan yprocesada para producir una matriz que usamos como un sustituto para caseosa. Este estudio ha demostrado la unión a esta matriz sustituta se correlaciona bien con la unión a caseosa, imitando eficazmente el proceso in vivo que impide la penetración del fármaco en el núcleo caseosa de granulomas y cavidades que de drogas.

<table><tbody><tr><td>New Zealand White Rabbits</td><td>Covance</td><td>-</td><td></td></tr><tr><td>HN878 Mycobacterium tuberculosis</td><td>BEI Resources</td><td>NR-13647&amp;nbsp;</td><td></td></tr><tr><td>Ketathesia (Ketamine) 100 mg/mL C3N</td><td>Henry Schein Animal Health</td><td>56344</td><td></td></tr><tr><td>Anased (Xylazine) 100 mg/mL</td><td>Henry Schein Animal Health</td><td>33198</td><td></td></tr><tr><td>Euthasol (pentobarbital sodium and phenytoin sodium) Solution&amp;nbsp;</td><td>Virbac</td><td>710101</td><td></td></tr><tr><td>THP-1 monocytic cell line</td><td>ATCC</td><td>ATCC TIB-202</td><td></td></tr><tr><td>175 cm&amp;sup2; TC-Treated Flask (T175)</td><td>Fisher Scientific</td><td>T-3400-175</td><td></td></tr><tr><td>RPMI 1640 media w/o glutamine</td><td>Fisher Scientific</td><td>MT-15-040-CV</td><td></td></tr><tr><td>Hyclone Fetal Bovine Serum, Gamma irradiated&amp;nbsp;</td><td>Fisher Scientific</td><td>SH3091003IR</td><td></td></tr><tr><td>Hyclone L-glutamine, 200 mM</td><td>Fisher Scientific</td><td>SH3003401</td><td></td></tr><tr><td>Cellstar TC dish, 145 mm x 20 mm, vented</td><td>Fisher Scientific</td><td>T-2881-1</td><td></td></tr><tr><td>Phorbol 12-myristate 13-acetate (PMA)</td><td>Fisher Scientific</td><td>BP685-1</td><td></td></tr><tr><td>Ethylenediaminetetraacetic acid</td><td>Sigma</td><td>E6758</td><td></td></tr><tr><td>Oleic acid&amp;nbsp;</td><td>Fisher Scientific</td><td>ICN15178101</td><td></td></tr><tr><td>Pierce RED Device Reusable Base Plate</td><td>Fisher Scientific</td><td>PI-89811</td><td></td></tr><tr><td>Pierce RED Device Inserts, 50/box&amp;nbsp;</td><td>Fisher Scientific</td><td>PI-89809</td><td></td></tr><tr><td>Pierce RED insert removal tool&amp;nbsp;</td><td>Fisher Scientific</td><td>89812</td><td></td></tr><tr><td>Adhesive plate seal</td><td>Fisher Scientific</td><td>08-408-240</td><td></td></tr><tr><td>PBS, pH 7.4, 10x 500 mL (Gibco)&amp;nbsp;</td><td>Life Technologies&amp;nbsp;</td><td>10010-049</td><td></td></tr><tr><td>DMSO</td><td>Sigma</td><td>472301</td><td></td></tr><tr><td>Acetonitrile</td><td>Sigma</td><td>34998</td><td></td></tr><tr><td>Methanol</td><td>Sigma</td><td>34860</td><td></td></tr><tr><td>Verapamil hydrochloride</td><td>Sigma</td><td>V4629</td><td></td></tr><tr><td>Diclofenac sodium salt</td><td>Sigma</td><td>93484</td><td></td></tr><tr><td>Trypan Blue Solution, 0.4%</td><td>Fisher Scientific</td><td>15-250-061</td><td></td></tr><tr><td>Ethanol, 200 proof</td><td>Fisher Scientific</td><td>04-355-451</td><td></td></tr><tr><td>2010 Geno/Grinder</td><td>SPEX SamplePrep</td><td>2010</td><td></td></tr><tr><td>Bead Mill Homogenizer Accessory, Metal Bulk Beads</td><td>Fisher Scientific</td><td>15-340-158</td><td></td></tr><tr><td>484R Cobalt 60 Irradiator</td><td>JL Shepard</td><td>7810-484-1</td><td></td></tr><tr><td>INCYTO&amp;nbsp;C-Chip Disposable Hemacytometers</td><td>Fisher Scientific</td><td>22-600-100</td><td></td></tr><tr><td>Upright Light Microscope</td><td>Leica</td><td>DM1000</td><td></td></tr><tr><td>Binary Liquid Chromatography system</td><td>Agilent</td><td>1260</td><td>Multi-compenent</td></tr><tr><td>Mass spectrometer</td><td>AB Sciex</td><td>4000</td><td></td></tr></tbody></table>

an in vitro caseum binding assay that predicts drug penetration in tuberculosis lesions

La erradicación de la enfermedad de la tuberculosis requiere regímenes farmacológicos que pueden penetrar las múltiples capas de lesiones pulmonares complejas. La distribución de fármacos en los núcleos caseosos de cavidades y lesiones es especialmente crucial porque albergan subpoblaciones de bacterias tolerantes a fármacos también comúnmente denominadas persisters. Los métodos existentes para la medición de la penetración del fármaco en lesiones de tuberculosis implican costosos y largos estudios farmacocinéticos in vivo acoplados a técnicas bioanalíticas o de formación de imágenes. La medida in vitro de la unión de fármacos a macromoléculas de caseo se propuso como una alternativa a tales técnicas ya que esta unión dificulta la difusión pasiva de moléculas de fármaco a través de caseo. La diálisis de equilibrio rápido es un sistema rápido y fiable para realizar estudios de unión a proteínas plasmáticas y tejidos. En este protocolo, se utilizó un dispositivo de diálisis de equilibrio rápido (RED) para medir la unión de fármacos a homogenados de caseo que es excised de las lesiones y de las cavidades de los conejos de tuberculosis infectados. El protocolo también se describe cómo generar una matriz sustituta de lípido cargado macrófagos THP-1 para utilizar en lugar de caseosa. Este / ensayo de unión sustituto caseosa es una herramienta importante en el descubrimiento de fármacos tuberculosis y se puede adaptar para ayudar a estudiar la distribución del fármaco en las lesiones o abscesos causados ​​por otras enfermedades.

Usando este protocolo, hemos probado cientos de compuestos de desarrollo de fármacos para la tuberculosis para su eficacia pronosticada en el caso de penetración. La figura 1 visualiza los conceptos básicos del ensayo RED. La membrana de diálisis de los insertos ROJO permite que pequeñas moléculas no unidas se difundan desde el pozo del donante hasta el pozo receptor, logrando finalmente un equilibrio entre ambos compartimentos. Las moléculas pequeñas que están ...

Watch this Scientific Journal Video about An In Vitro Caseum Binding Assay that Predicts Drug Penetration in Tuberculosis Lesions at JoVE.com

An In Vitro Caseum Binding Assay that Predicts Drug Penetration in Tuberculosis Lesions

En este artículo se describe un método de diálisis de equilibrio rápido (RED) para medir la unión de fármacos a caseum de lesiones y cavidades de tuberculosis pulmonar. El protocolo también se utiliza con una matriz espumosa derivada de macrófagos que es un sustituto efectivo del caseo.

Un<em&gt; In Vitro</em&gt; Caseosa Ensayo de unión que permite predecir la penetración de fármacos en la tuberculosis lesiones

The eradication of tuberculosis disease requires drug regimens that can penetrate the multiple layers of complex pulmonary lesions. Drug distribution in ...

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Pharmacokinetics and Pharmacodynamics

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Unit 1

An In Vitro Caseum Binding Assay that Predicts Drug Penetration in Tuberculosis Lesions

Nonlinear Pharmacokinetics

Introduction to Respiratory System Drugs

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11.7K vistas.  Rutgers.  En este artículo se describe un método de diálisis de equilibrio rápido (RED) para medir la unión de fármacos a caseum de lesiones y cavidades de tuberculosis pulmonar. El protocolo también se utiliza con una matriz espumosa derivada de macrófagos que es un sustituto efectivo del caseo. 

Video: An In Vitro Caseum Binding Assay that Predicts Drug Penetration in Tuberculosis Lesions

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.

Un Ensayo Fenotípico Microscópico Para La Cuantificación De Micobacterias Intracelulares Adaptadas Para La Detección De Alto Rendimiento / Alto Contenido

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

Investigación

Inmunología e Infección

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.

La visualización de la resazurina prueba de carbón en agar para semi-cuantitativa, Enumeración de mediano rendimiento de Micobacterias

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

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.

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

We have developed a modular high-throughput screening system for discovering novel compounds against Mycobacterium tuberculosis, targeting intracellular and in-broth growing bacteria as well as cytotoxicity against the mammalian host cell.

Sistema para la eficacia y la citotoxicidad de detección de inhibidores de focalización intracelular<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 ...

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.

Un ensayo compatible de alto rendimiento para evaluar la eficacia del fármaco contra los macrófagos a pases<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 ...

A Tuberculosis Molecular Bacterial Load Assay (TB-MBLA)

Tuberculosis is caused by Mycobacterium tuberculosis (Mtb), a pathogen classified by the United Nations (UN) as a dangerous category B biological substance. For the sake of the workers&#8217; safety, handling of all samples presumed to carry Mtb must be conducted in a containment level (CL) 3 laboratory. The TB molecular bacterial load assay (TB-MBLA) test is a reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) test that quantifies Mtb bacillary load using primers and dual-labelled probes for 16S rRNA. We describe the use of heat inactivation to render TB samples noninfectious while preserving RNA for the TB-MBLA. A 1 mL aliquot of the sputum sample in tightly closed 15 mL centrifuge tubes is boiled for 20 min at either 80 &#176;C, 85 &#176;C, or 95 &#176;C to inactivate Mtb bacilli. Cultivation of the heat inactivated and control (live) samples for 42 days confirmed the death of TB. The inactivated sample is then spiked with 100 &#181;L of the extraction control and RNA is extracted following the standard RNA isolation procedure. No growth was observed in the cultures of heat treated samples. The isolated RNA is subjected to real-time RT-qPCR, which amplifies a specific target in the Mtb 16S rRNA gene, yielding results in the form of quantification cycles (Cq). A standard curve is used to translate Cq into bacterial load, or estimated colony forming units per mL (eCFU/mL). There is an inverse relationship between Cq and the bacterial load of a sample. The limitation is that heat inactivation lyses some cells, exposing the RNA to RNases that cause a loss of &#60;1 log10eCFU/mL (i.e., &#60;10 CFU/mL). Further studies will determine the proportion of very low burden patients that cause false negative results due to heat inactivation.

A Tuberculosis Molecular Bacterial Load Assay TB-MBLA

We describe a tuberculosis molecular bacterial load assay test performed after heat inactivation of sputum. Heat inactivation renders sputum samples noninfectious and obviates the need for containment level 3 laboratories for tuberculosis molecular tests.

Un ensayo de carga bacteriana molecular de la tuberculosis (TB-MBLA)

Tuberculosis is caused by Mycobacterium tuberculosis (Mtb), a pathogen classified by the United Nations (UN) as a dangerous category B biological ...

Spatial Quantification of Drugs in Pulmonary Tuberculosis Lesions by Laser Capture Microdissection Liquid Chromatography Mass Spectrometry (LCM-LC/MS)

Tuberculosis is still a leading cause of morbidity and mortality worldwide. Improvements to existing drug regimens and the development of novel therapeutics are urgently required. The ability of dosed TB drugs to reach and sterilize bacteria within poorly-vascularized necrotic regions (caseum) of pulmonary granulomas is crucial for successful therapeutic intervention. Effective therapeutic regimens must therefore contain drugs with favorable caseum penetration properties. Current LC/MS methods for quantifying drug levels in biological tissues have limited spatial resolution capabilities, making it difficult to accurately determine absolute drug concentrations within small tissue compartments such as those found within necrotic granulomas. Here we present a protocol combining laser capture microdissection (LCM) of pathologically-distinct tissue regions with LC/MS quantification. This technique provides absolute quantification of drugs within granuloma caseum, surrounding cellular lesion and uninvolved lung tissue and, therefore, accurately determines whether bactericidal concentrations are being achieved. In addition to tuberculosis research, the technique has many potential applications for spatially-resolved quantification of drugs in diseased tissues.

Spatial Quantification of Drugs in Pulmonary Tuberculosis Lesions by Laser Capture Microdissection Liquid Chromatography Mass Spectrometry LCM-LC/MS

Here, we describe a protocol using laser capture microdissection coupled with LC/MS analysis to spatially-quantify drug distributions within pulmonary tuberculosis granulomas. The approach has broad applicability to quantifying drug concentrations within tissues at high spatial detail.

Cuantificación espacial de fármacos en lesiones de Tuberculosis pulmonar por Laser Capture Microdissection líquido cromatografía espectrometría de masas (LCM-LC/MS)

Tuberculosis is still a leading cause of morbidity and mortality worldwide. Improvements to existing drug regimens and the development of novel ...

Medicina

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.

Un sistema de cultivo automatizado para su uso en pruebas preclínicas de terapias dirigidas al huésped para la tuberculosis

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>Ensayo de cribado de alto rendimiento para Mycobacterium abscessus mediante reporteros duales

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 destacado: Protocolo escalable de detección de fármacos para el descubrimiento eficiente de tratamientos para M. abscessus

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.

Desarrollo de ensayos para el cribado de fármacos de alto rendimiento contra micobacterias

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

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