Esta investigación fue financiada en parte por los premios NIH 5T32AI07506, 5R01AI033774, 5R37AI033142, 5R01AI052733.

Todo el trabajo de los animales se realizó de conformidad con los reglamentos y directrices del Instituto de Estudios en animales en el Albert Einstein College of Medicine. 1. Crecimiento Condiciones de C. neoformans H99 (serotipo A) <ol><li> Crecer individuo C. neoformans (CN) colonias sobre placas de agar Sabouraud. </li><li> Un día antes del experimento, seleccione una colonia e inocular 10 ml de caldo de Sabouraud. </li><li> Permitir que la cultura de crecer durante la noche a 37 ° C con agitación a una velocidad de 250 rpm. </li></ol> 2 Aislamiento y preparación de Primaria hueso macrófagos de C57 / Bl6 Ratones <ol><li> La eutanasia a los ratones mediante la colocación de los animales en una cámara de CO 2 hasta que no la respiración por más tiempo. Como segunda medida, cervical dislocar el cuello antes de comenzar la disección. Esterilizar todo el cuerpo con un 70% de alcohol etílico. </li><li> Retire ambos fémures y los huesos de tibia y colocar en DMEM estéril. </li><li> Retire el exceso de tejido y músculo de usolicate limpia hasta que los huesos están completamente limpias. </li><li> Coloque los huesos intactos sólo en una placa de Petri que contiene 70% de alcohol etílico y se incuba durante 3 min para matar los microorganismos asociados. Quitar los huesos y el lugar en el plato de Petri con DMEM estéril. </li><li> Corte cuidadosamente los extremos de los huesos. Mantenga el hueso largo de un tubo cónico de 50 ml vacías colocado en hielo y enjuague cuidadosamente 10 ml de DMEM frío utilizando una aguja de 25 G a través de cada hueso. NOTA: Cada ratón producirá 4 huesos (2 fémures, tibias 2). Por lo tanto un ratón debe producir aproximadamente 40 ml de suspensión celular. </li><li> Centrifugar la suspensión celular a temperatura ambiente durante 10 min a 650 x g. </li><li> Durante esta centrifugación, preparar y esterilizar por filtración macrófagos de médula ósea alimentación de los medios de comunicación que consiste en DMEM suplementado con 20% L929, 10% de suero de ternera fetal, 10% NCTC-109, 1% de Pen-Strep, 1% HEPES, 1% de L-glutamina , 1% de aminoácidos no esenciales, 0,1% de 2-mercaptoetanol. </li><li> Resuspender el sedimento resultante con 10 ml de la alimentación de los medios de comunicación. Pase suspens celularesiones a través de un colador de 70 micras de células para alterar grupos de células y eliminar los residuos de gran tamaño. </li><li> Placa 1 ml de la suspensión celular en 10 ml de medio de alimentación en placas de Petri que se especifican para el uso de cultivo de tejidos (para un total de 10 placas). </li><li> Permitir que las células se adhieran a 37 ° C con 10% de CO 2. Añadir 5 ml de medio de alimentación fresca en el día 3 En el día 7, reemplazar por completo los medios de alimentación y los macrófagos están listos para ser utilizados. </li><li> El día antes del experimento, separar los macrófagos de la placa mediante la eliminación de los medios de alimentación y añadir 5 ml de una célula suave extracción de reactivos a la placa. </li><li> Incubar durante 5-10 minutos a 37 ° C y retirar los macrófagos con pipeteo suave. </li><li> Precipitar las células por centrifugación a 650 xg durante 10 min. </li><li> Resuspender pellet en 1 ml de la alimentación de los medios de comunicación. Uso de una dilución 1:20, calcular la concentración de los macrófagos pipeteando 10 l de suspensión de células en un hemocitómetro. </li><li> El uso de 14 mm con fondo de cristal cajas de Petri, plato unconcentración de 1 x 10 5 macrófagos directamente sobre el pozo interior que tiene una capacidad máxima de 200 l, así que tome precauciones para no exceder este volumen, como se muestra en la Figura 4. </li><li> Permitir que las células se adhieren a la placa de Petri de vidrio mediante la colocación de los platos en un 37 ° C incubadora durante 1 hr. </li><li> Añadir 1-2 ml de la alimentación de medio suplementado con LPS a 1 mg / ml y IFNg en 500 u / ml y permiten a las células se incuban durante la noche. </li></ol> 3. Co-incubación de primaria murino macrófagos y C. neoformans <ol><li> En el día del experimento, eliminar 1 ml de células de cultivo de levadura y pellet inoculados durante la noche por centrifugación durante 5 min a 420 x g. </li><li> Lavar las células 3 veces con PBS estéril para eliminar los medios de comunicación y productos criptocócicas extracelulares como el glucuronoxylomanan polisacárido (GXM) a la velocidad y el tiempo mencionado anteriormente. </li><li> Resuspender sedimento celular en 1 ml de PBS estéril y crea una dilución 1: 100. Pipeta de 10 l de tél dilución en un hemocitómetro y contar las células. Añadir células de levadura a una MOI de 1: 5. Por ejemplo, si hay 1 x 10 5 macrófagos / bien, hacer una suspensión de células de 5 x 10 6 / ml de Cn y añadir 100 ml de esta solución por un importe total de 5 x 10 5 Cn. </li><li> Añadir el volumen calculado de suspensión de células criptocócica a 1 ml de medio de alimentación con el anticuerpo mAb 18B7 a una concentración de 10 mg / ml. Incubar suspensión de células a temperatura ambiente durante 5 min. </li><li> Retire el medio de alimentación de fondo de cristal placa de Petri y se lavan con PBS 1x estéril. Añadir 100 l de opsonizado Cn directamente al bien. </li><li> Permitir que las células se incuban durante 2 horas a 37 ° C con 10% de CO 2. </li><li> Después de co-incubación, comprobar al microscopio que los macrófagos han interiorizado Cn. Para ser considerado interiorizado, células criptocócicas claramente deben ser vistos dentro de los confines de los macrófagos. </li><li> Lave 3x plato de Petri con PBS estéril para eliminar cualquier y toda extracellular Cn. </li><li> Añadir 1-2 ml de la alimentación de los medios de comunicación sin la adición de mAb 18B7, y establecer microscopio. </li></ol> 4. Visualizing no lítico exocitosis en Utilizando microscopía de luz digital en tiempo real NOTA: Para realizar estos experimentos, un microscopio que viene con una cámara de incubación adjunto que incluye CO 2 y la entrega se requiere una unidad de calentamiento. <ol><li> Antes del experimento, pre-calentar la cámara de incubación durante al menos 30 min a 37 ° C. Asegúrese de que la unidad de CO 2 lee 5% al inicio del experimento. </li><li> Lugar con fondo de cristal placa de Petri en la plataforma del microscopio, cubrir con CO 2 tapa y cierre todas las puertas para asegurar que no escapa el calor. </li><li> Usando el objetivo de 10X con el microscopio de contraste de fase en, se centran en un claro campo de macrófagos infectados. Basado en el experimento, determinar el objetivo utilizado por el número de macrófagos que ser estudiados. </li><li> Configure el software de microscopio para take una imagen cada 4 minutos durante un período de 24 horas. </li><li> Después de 24 horas, el experimento habrá llegado a su conclusión y se habrá recogido un total de 361 imágenes. Exportación de estas imágenes como .jpegs a una compresión del 5%. El uso de la imagen J software, ver las imágenes como una pila Visual a los 5 fotogramas por segundo. Si la película tiene que ser vista para su publicación o una presentación, guardarla como tampoco un avi o mov archivo dependiendo del formato funciona mejor para el espectador. </li></ol>

<ol>
	<li>Voelz, K., May, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryptococcal+Interactions+With+the+Host+Immune+System.">Cryptococcal Interactions With the Host Immune System.</a> Eukaryotic cell. 9 (6), 835-846 (2010).</li><li>Johnston, S. A., May, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cryptococcus+interactions+with+macrophages:+evasion+and+manipulation+of+the+phagosome+by+a+fungal+pathogen.">Cryptococcus interactions with macrophages: evasion and manipulation of the phagosome by a fungal pathogen.</a> Cellular microbiology. 15 (3), 403-411 (2012).</li><li>Sabiiti, W., May, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+infection+by+the+human+fungal+pathogen+Cryptococcus+neoformans.">Mechanisms of infection by the human fungal pathogen Cryptococcus neoformans.</a> Future microbiology. 7 (11), 1297-1313 (2012).</li><li>Bliska, J. B., Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+pathogenic+bacteria+and+fungi+&#8212;+a+case+of+convergent+evolution.">Intracellular pathogenic bacteria and fungi &#8212; a case of convergent evolution.</a> Nature Reviews Microbiology. 7, 165-171 (2008).</li><li>Alvarez, M., Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell-to-cell+spread+and+massive+vacuole+formation+after+Cryptococcus+neoformans+infection+of+murine+macrophages.">Cell-to-cell spread and massive vacuole formation after Cryptococcus neoformans infection of murine macrophages.</a> BMC immunology. 8 (1), 16 (2007).</li><li>Ma, H., Croudace, J. E., Lammas, D. A., May, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+cell-to-cell+spread+of+a+pathogenic+yeast.">Direct cell-to-cell spread of a pathogenic yeast.</a> BMC immunology. 8, 15 (2007).</li><li>Alvarez, M., Casadevall, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phagosome+extrusion+and+host-cell+survival+after+Cryptococcus+neoformans+phagocytosis+by+macrophages.">Phagosome extrusion and host-cell survival after Cryptococcus neoformans phagocytosis by macrophages.</a> Curr Biol. 16 (21), 2161-2165 (2006).</li><li>Ma, H., Croudace, J. E., Lammas, D. A., May, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expulsion+of+live+pathogenic+yeast+by+macrophages.">Expulsion of live pathogenic yeast by macrophages.</a> Curr Biol. 16 (21), 2156-2160 (2006).</li><li>Johnston, S. A., May, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+human+fungal+pathogen+Cryptococcus+neoformans+escapes+macrophages+by+a+phagosome+emptying+mechanism+that+is+inhibited+by+Arp2/3+complex-mediated+actin+polymerisation.">The human fungal pathogen Cryptococcus neoformans escapes macrophages by a phagosome emptying mechanism that is inhibited by Arp2/3 complex-mediated actin polymerisation.</a> PLoS pathogens. 6 (8), (2010).</li><li>Carnell, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Actin+polymerization+driven+by+WASH+causes+V-ATPase+retrieval+and+vesicle+neutralization+before+exocytosis.">Actin polymerization driven by WASH causes V-ATPase retrieval and vesicle neutralization before exocytosis.</a> The Journal of cell biology. 193 (5), 831-839 (2011).</li><li>Voelz, K., Lammas, D. A., May, R. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cytokine+signaling+regulates+the+outcome+of+intracellular+macrophage+parasitism+by+Cryptococcus+neoformans.">Cytokine signaling regulates the outcome of intracellular macrophage parasitism by Cryptococcus neoformans.</a> Infection and immunity. 77 (8), 3450-3457 (2009).</li><li>Bain, M. J., Lewis, E. L., Okai, B., Quinn, J., Gow, A. R. N., Erwig, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-lytic+expulsion/exocytosis+of+Candida+albicans+from+macrophages.">Non-lytic expulsion/exocytosis of Candida albicans from macrophages.</a> Fungal genetics and biology. 49 (9), 677-678 (2012).</li></ol>

Los autores declaran que no tenemos que compiten intereses financieros u otros conflictos de intereses.

Aquí hemos descrito un método por el cual las interacciones fúngicas macrófagos pueden ser registradas y analizadas en tiempo real durante un período de 24 h. Nuestro laboratorio ha utilizado este protocolo para estudiar muchos de los aspectos temporales de la exocitosis no lítico y seguirá utilizando microscopía en tiempo real para determinar los componentes morfológicos que rodean este proceso. Para esta técnica para producir resultados ideales, especial atención se debe dar a c...

Las fases de una infección por hongos entre las células criptocócica y macrófagos están bien documentados 1-3. Después de células de levadura son ingeridos por macrófagos, una variedad de interacciones pueden ocurrir: el macrófago puede lisar liberando su carga fúngica en el espacio extracelular, o podría controlar la infección por el mantenimiento de las células de levadura dentro de los confines de su membrana celular 4. Sin embargo, hace varios años un nuevo resultado fue descrita independientemente por dos grupos: exocitosis no lítico, un proceso en el que un macrófago borrado algunas o todas de las células criptocócica en el ambiente circundante o una célula vecina y ambos huésped y patógeno se mantienen viables 5 -8. Varios estudios han tratado de comprender los mecanismos moleculares detrás de esta interacción, pero todavía no tienen una comprensión completa de lo que impulsa a este fenómeno. La capacidad para capturar imágenes en tiempo real y luego analizar posteriormente múltiples Infected macrófagos permite responder a muchas preguntas sobre las propiedades físicas que rodean la exocitosis no lítico en cuanto a tiempo, la capacidad espacial, el cambio en la morfología e incluso el estrés de los macrófagos durante una infección por hongos. Al permitir que las células que se encuentran en un entorno que sea comparable a la de una incubadora, podemos vislumbrar la naturaleza dinámica de las interacciones de células de tipo macrófago por hongos. Los investigadores han utilizado esta técnica para estudiar diversos componentes de este proceso. El papel del fagosoma en este proceso se hizo evidente mediante la tinción de actina fluorescente y agentes de bloqueo 9, mientras que otro grupo utilizó este método para mostrar que la exocitosis no lítico fue bloqueada en las células que han tenido la nucleación WASH dominios de la proteína suprime 10. El efecto de la señalización de citoquinas también ha sido comprobada mediante microscopía en tiempo real 11. Este proceso no se limita a C. neoformans como también se ha observado con Candida albicans, another patógeno fúngico que tiene la capacidad de infectar a los macrófagos 12. Estos hallazgos son ejemplos de cómo este método puede proporcionar una gran cantidad de información a un área que sabemos tan poco.

<table><tbody><tr><td>Sabouraud Dextrose Agar</td><td>BD</td><td>DF0109-17-1</td><td></td></tr><tr><td>Sabouraud Dextrose Broth</td><td>BD</td><td>DF0382-17-9</td><td></td></tr><tr><td>Dubelcco&#039;s Modified Eagle&#039;s Medium (DMEM)</td><td>Corning Cellgro</td><td>10-013-CV</td><td></td></tr><tr><td>Fetal Calf Serum (FCS)</td><td>Atlanta Biologicals</td><td>S12450</td><td></td></tr><tr><td>NCTC 109</td><td>Invitrogen</td><td>21340-039</td><td></td></tr><tr><td>Penicillin-Streptomycin</td><td>Gibco</td><td>15140-122</td><td></td></tr><tr><td>HEPES Buffer</td><td>Corning Cellgro</td><td>25-060-Cl</td><td></td></tr><tr><td>Glutamax</td><td>Invitrogen</td><td>35050-061</td><td></td></tr><tr><td>Non-essential Amino Acids</td><td>Corning Cellgro</td><td>25-025-Cl</td><td></td></tr><tr><td>2-Mercaptoethanol</td><td>Invitrogen</td><td>21985-023</td><td>Toxic</td></tr><tr><td>3003 Tissue Culture Petri Dishes&amp;nbsp;</td><td>Fisher Scientific&amp;nbsp;</td><td>08772E</td><td></td></tr><tr><td>CellStripper</td><td>Corning Cellgro</td><td>25-056-Cl</td><td></td></tr><tr><td>Mat-tek Glass Bottom Culture Dishes</td><td>MatTek</td><td>P35GC-1.5-14-C</td><td></td></tr><tr><td>LPS</td><td>Sigma</td><td>L3137</td><td></td></tr><tr><td>Mouse IFN-g</td><td>Roche</td><td>NC 9222016</td><td></td></tr><tr><td>mAb 18B7</td><td>Non-commerical antibody produced in our lab</td><td></td><td></td></tr><tr><td>Axiovert 200M Microscope with Incubating Chamber</td><td>Zeiss</td><td></td><td></td></tr></tbody></table>

visualizing non-lytic exocytosis of cryptococcus neoformans from macrophages using digital light microscopy

Muchos aspectos de la infección de macrófagos por Cryptococcus neoformans han sido ampliamente estudiados y bien definido. Sin embargo, una interacción particular que no se entiende claramente es la exocitosis no lítico. En este proceso, las células de levadura se liberan en el espacio extracelular mediante un mecanismo mal entendido que deja tanto el macrófago y Cn viable. Aquí se describe cómo seguir un gran número de macrófagos infectados individualmente para un período de infección 24 h por microscopía de tiempo transcurrido. Macrófagos infectados se encuentran en una cámara de calentamiento con una atmósfera de CO 2 unido a un microscopio que ofrece las mismas condiciones que una incubadora de cultivo celular. Microscopía digital de vivo puede proporcionar información acerca de las interacciones dinámicas entre un huésped y patógeno que no está disponible a partir de imágenes estáticas. Ser capaz de visualizar cada célula infectada puede proporcionar pistas sobre cómo los macrófagos manejan las infecciones por hongos, y viceversa. Esta técnica isa poderosa herramienta en el estudio de las dinámicas que están detrás de un fenómeno complejo.

Las imágenes que esta técnica produce pueden ser analizados en una variedad de maneras de recoger información en torno a lo que sucede después de las células han fagocitado C. neoformans. Como se ve en la Figura 1, hay aproximadamente 100 macrófagos que están infectados o no infectados. Cada uno de estos macrófagos da al espectador la oportunidad de estudiar las interacciones huésped-patógeno en un nivel muy microscópico. Como muestran las figuras 2 y 3</stro...

Watch this Scientific Journal Video about Visualizing Non-lytic Exocytosis of Cryptococcus neoformans from Macrophages Using Digital Light Microscopy at JoVE.com

Visualizing Non-lytic Exocytosis of Cryptococcus neoformans from Macrophages Using Digital Light Microscopy

Se describe cómo visualizar macrófagos C. neoformans (Cn) interacciones en tiempo real, con especial énfasis en el proceso de exocitosis no lítico usando microscopía de luz digital. Usando esta técnica de forma individual los macrófagos infectados se puede estudiar para determinar varios aspectos de este fenómeno.

La visualización no lítico exocitosis de<em&gt; Cryptococcus neoformans</em&gt; De macrófagos Usando microscopía de luz digital

Many aspects of the infection of macrophages by Cryptococcus neoformans have been extensively studied and well defined. However, one particular ...

visualizing-non-lytic-exocytosis-cryptococcus-neoformans-from

Research

JoVE Journal

Immunology and Infection

Visualizing Non-lytic Exocytosis of Cryptococcus neoformans from Macrophages Using Digital Light Microscopy

11.8K vistas.  Albert Einstein College of Medicine.  Se describe cómo visualizar macrófagos C. neoformans (Cn) interacciones en tiempo real, con especial énfasis en el proceso de exocitosis no lítico usando microscopía de luz digital. Usando esta técnica de forma individual los macrófagos infectados se puede estudiar para determinar varios aspectos de este fenómeno. 

Video: Visualizing Non-lytic Exocytosis of Cryptococcus neoformans from Macrophages Using Digital Light Microscopy

Live-cell Video Microscopy of Fungal Pathogen Phagocytosis

Phagocytic clearance of fungal pathogens, and microorganisms more generally, may be considered to consist of four distinct stages: (i) migration of phagocytes to the site where pathogens are located; (ii) recognition of pathogen-associated molecular patterns (PAMPs) through pattern recognition receptors (PRRs); (iii) engulfment of microorganisms bound to the phagocyte cell membrane, and (iv) processing of engulfed cells within maturing phagosomes and digestion of the ingested particle. Studies that assess phagocytosis in its entirety are informative1, 2, 3, 4, 5 but are limited in that they do not normally break the process down into migration, engulfment and phagosome maturation, which may be affected differentially. Furthermore, such studies assess uptake as a single event, rather than as a continuous dynamic process. We have recently developed advanced live-cell imaging technologies, and have combined these with genetic functional analysis of both pathogen and host cells to create a cross-disciplinary platform for the analysis of innate immune cell function and fungal pathogenesis. These studies have revealed novel aspects of phagocytosis that could only be observed using systematic temporal analysis of the molecular and cellular interactions between human phagocytes and fungal pathogens and infectious microorganisms more generally. For example, we have begun to define the following: (a) the components of the cell surface required for each stage of the process of recognition, engulfment and killing of fungal cells1, 6, 7, 8; (b) how surface geometry influences the efficiency of macrophage uptake and killing of yeast and hyphal cells7; and (c) how engulfment leads to alteration of the cell cycle and behavior of macrophages 9, 10.
In contrast to single time point snapshots, live-cell video microscopy enables a wide variety of host cells and pathogens to be studied as continuous sequences over lengthy time periods, providing spatial and temporal information on a broad range of dynamic processes, including cell migration, replication and vesicular trafficking. Here we describe in detail how to prepare host and fungal cells, and to conduct the video microscopy experiments. These methods can provide a user-guide for future studies with other phagocytes and microorganisms.

We describe methods for live-cell video microscopy of Candida albicans phagocytosis by macrophages. These methods enable stage-specific analysis of macrophage migration, recognition, engulfment and phagosome maturation and reveal novel aspects of phagocytosis.

Vídeo en vivo de células Microscopía de fagocitosis hongo patógeno

Phagocytic clearance of fungal pathogens, and microorganisms more generally, may be considered to consist of four distinct stages: (i) migration of ...

Investigación

Inmunología e Infección

Use of Image Cytometry for Quantification of Pathogenic Fungi in Association with Host Cells

Studies of the cellular pathogenesis mechanisms of pathogenic yeasts such as Candida albicans, Histoplasma capsulatum, and Cryptococcus neoformans commonly employ infection of mammalian hosts or host cells (i.e. macrophages) followed by yeast quantification using colony forming unit analysis or flow cytometry. While colony forming unit enumeration has been the most commonly used method in the field, this technique has disadvantages and limitations, including slow growth of some fungal species on solid media and low and/or variable plating efficiencies, which is of particular concern when comparing growth of wild-type and mutant strains. Flow cytometry can provide rapid quantitative information regarding yeast viability, however, adoption of flow cytometric detection for pathogenic yeasts has been limited for a number of practical reasons including its high cost and biosafety considerations. Here, we demonstrate an image-based cytometric methodology using the Cellometer Vision (Nexcelom Bioscience, LLC) for the quantification of viable pathogenic yeasts in co-culture with macrophages. Our studies focus on detection of two human fungal pathogens: Histoplasma capsulatum and Candida albicans. H. capsulatum colonizes alveolar macrophages by replicating within the macrophage phagosome, and here, we quantitatively assess the growth of H. capsulatum yeasts in RAW 264.7 macrophages using acridine orange/propidium iodide staining in combination with image cytometry. Our method faithfully recapitulates growth trends as measured by traditional colony forming unit enumeration, but with significantly increased sensitivity. Additionally, we directly assess infection of live macrophages with a GFP-expressing strain of C. albicans. Our methodology offers a rapid, accurate, and economical means for detection and quantification of important human fungal pathogens in association with host cells.

Here, we demonstrate how image cytometry can be used for quantification of pathogenic fungi in association with host cells in culture. This technique can be used as an alternative to CFU enumeration.

El uso de citometría de imagen para la cuantificación de hongos patógenos en asociación con las células huésped

Studies of the cellular pathogenesis mechanisms of pathogenic yeasts such as Candida albicans, Histoplasma capsulatum, and Cryptococcus neoformans ...

Assessing Anti-fungal Activity of Isolated Alveolar Macrophages by Confocal Microscopy

The lung is an interface where host cells are routinely exposed to microbes and microbial products. Alveolar macrophages are the first-line phagocytic cells that encounter inhaled fungi and other microbes. Macrophages and other immune cells recognize Aspergillus motifs by pathogen recognition receptors and initiate downstream inflammatory responses. The phagocyte NADPH oxidase generates reactive oxygen intermediates (ROIs) and is critical for host defense. Although NADPH oxidase is critical for neutrophil-mediated host defense1-3, the importance of NADPH oxidase in macrophages is not well defined. The goal of this study was to delineate the specific role of NADPH oxidase in macrophages in mediating host defense against A. fumigatus. We found that NADPH oxidase in alveolar macrophages controls the growth of phagocytosed A. fumigatus spores4. Here, we describe a method for assessing the ability of mouse alveolar macrophages (AMs) to control the growth of phagocytosed Aspergillus spores (conidia). Alveolar macrophages are stained in vivo and ten days later isolated from mice by bronchoalveolar lavage (BAL). Macrophages are plated onto glass coverslips, then seeded with green fluorescent protein (GFP)-expressing A. fumigatus spores. At specified times, cells are fixed and the number of intact macrophages with phagocytosed spores is assessed by confocal microscopy.

A method to evaluate the ability of isolated mouse alveolar macrophages to control the growth of phagocytosed Aspergillus spores by confocal microscopy.

La evaluación de la actividad anti-fúngica de aislados macrófagos alveolares por microscopía confocal

The lung is an interface where host cells are routinely exposed to microbes and microbial products. Alveolar macrophages are the first-line phagocytic ...

Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans

Cryptococcosis is a life-threatening infection caused by pathogenic fungi of the genus Cryptococcus. Infection occurs upon inhalation of spores, which are able to replicate in the deep lung. Phagocytosis of Cryptococcus by macrophages is one of the ways that the disease is able to spread into the central nervous system to cause lethal meningoencephalitis. Therefore, study of the association between Cryptococcus and macrophages is important to understanding the progression of the infection. The present study describes a step-by-step protocol to study macrophage infectivity by C. neoformansin vitro. Using this protocol, the role of host sterols on host-pathogen interactions is studied. Different concentrations of methyl--cyclodextrin (MCD) were used to deplete cholesterol from murine reticulum sarcoma macrophage-like cell line J774A.1. Cholesterol depletion was confirmed and quantified using both a commercially available cholesterol quantification kit and thin layer chromatography. Cholesterol depleted cells were activated using Lipopolysacharide (LPS) and Interferon gamma (IFN&#947;) and infected with antibody-opsonized Cryptococcus neoformans wild-type H99 cells at an effector-to-target ratio of 1:1. Infected cells were monitored after 2 hr of incubation with C. neoformans and their phagocytic index was calculated. Cholesterol depletion resulted in a significant reduction in the phagocytic index. The presented protocols offer a convenient method to mimic the initiation of the infection process in a laboratory environment and study the role of host lipid composition on infectivity.

Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans

In this article, a protocol for infection of macrophages with Cryptococcus neoformans is described. Also, a method for sterol depletion from the macrophages is explained. These protocols provide a guide to study fungal infections in vitro and examine the role of sterols in such infections.

El colesterol de los macrófagos agotamiento y su efecto sobre la fagocitosis de<em&gt; Cryptococcus neoformans</em

Cryptococcosis is a life-threatening infection caused by pathogenic fungi of the genus Cryptococcus. Infection occurs upon inhalation of spores, which are ...

Time-lapse 3D Imaging of Phagocytosis by Mouse Macrophages

Phagocytosis plays a key role in host defense, as well as in tissue development and maintenance, and involves rapid, receptor-mediated rearrangements of the actin cytoskeleton to capture, envelop and engulf large particles. Although phagocytic receptors, downstream signaling pathways, and effectors, such as Rho GTPases, have been identified, the dynamic cytoskeletal remodeling of specific receptor-mediated phagocytic events remain unclear. Four decades ago, two distinct mechanisms of phagocytosis, exemplified by Fc&#947; receptor (Fc&#947;R)- and complement receptor (CR)-mediated phagocytosis, were identified using scanning electron microscopy. Binding of immunoglobulin G (IgG)-opsonized particles to Fc&#947;Rs triggers the protrusion of thin membrane extensions, which initially form a so-called phagocytic cup around the particle before it becomes completely enclosed and retracted into the cell. In contrast, complement opsonized particles appear to sink into the phagocyte following binding to complement receptors. These two modes of phagocytosis, phagocytic cup formation and sinking in, have become well established in the literature. However, the distinctions between the two modes have become blurred by reports that complement receptor-mediated phagocytosis may induce various membrane protrusions. With the availability of high resolution imaging techniques, phagocytosis assays are required that allow real-time 3D (three dimensional) visualization of how specific phagocytic receptors mediate the uptake of individual particles. More commonly used approaches for the study of phagocytosis, such as end-point assays, miss the opportunity to understand what is happening at the interface of particles and phagocytes. Here we describe phagocytic assays, using time-lapse spinning disk confocal microscopy, that allow 3D imaging of single phagocytic events. In addition, we describe assays to unambiguously image Fc&#947; receptor- or complement receptor-mediated phagocytosis.

Here we describe methods using spinning disk confocal microscopy to image single phagocytic events by mouse resident peritoneal macrophages. The protocols can be extended to other phagocytic cells.

Proyección de imagen 3D Time-lapse de la fagocitosis por macrófagos de ratón

Phagocytosis plays a key role in host defense, as well as in tissue development and maintenance, and involves rapid, receptor-mediated rearrangements of ...

Complementary Use of Microscopic Techniques and Fluorescence Reading in Studying Cryptococcus-Amoeba Interactions

To simulate Cryptococcus infection, amoeba, which is the natural predator of cryptococcal cells in the environment, can be used as a model for macrophages. This predatory organism, similar to macrophages, employs phagocytosis to kill internalized cells. With the aid of a confocal laser-scanning microscope, images depicting interactive moments between cryptococcal cells and amoeba are captured. The resolution power of the electron microscope also helps to reveal the ultrastructural detail of cryptococcal cells when trapped inside the amoeba food vacuole. Since phagocytosis is a continuous process, quantitative data is then integrated in the analysis to explain what happens at the timepoint when an image is captured. To be specific, relative fluorescence units are read in order to quantify the efficiency of amoeba in internalizing cryptococcal cells. For this purpose, cryptococcal cells are stained with a dye that makes them fluoresce once trapped inside the acidic environment of the food vacuole. When used together, information gathered through such techniques can provide critical information to help draw conclusions on the behavior and fate of cells when internalized by amoeba and, possibly, by other phagocytic cells.

Complementary Use of Microscopic Techniques and Fluorescence Reading in Studying Cryptococcus-Amoeba Interactions

This paper details a protocol for preparing a co-culture of cryptococcal cells and amoebae that is studied using still, fluorescent images and high-resolution transmission electron microscope images. Illustrated here is how quantitative data can complement such qualitative information.

Uso complementario de técnicas microscópicas y lectura de fluorescencia en el estudio de las interacciones Cryptococcus-Amoeba

To simulate Cryptococcus infection, amoeba, which is the natural predator of cryptococcal cells in the environment, can be used as a model for ...

Visualization of Macrophage Lytic Cell Death During Mycobacterial Infection in Zebrafish Embryos via Intravital Microscopy

Zebrafish is an excellent model organism for studying innate immune cell behavior due to its transparent nature and reliance solely on its innate immune system during early development. The Zebrafish Mycobacterium marinum (M. marinum) infection model has been well-established in studying host immune response against mycobacterial infection. It has been suggested that different macrophage cell death types will lead to the diverse outcomes of mycobacterial infection. Here we describe a protocol using intravital microscopy to observe macrophage cell death in zebrafish embryos following M. marinum infection. Zebrafish transgenic lines that specifically label macrophages and neutrophils are infected via intramuscular microinjection of fluorescently labeled M. marinum in either the midbrain or the trunk. Infected zebrafish embryos are subsequently mounted on low melting agarose and observed by confocal microscopy in X-Y-Z-T dimensions. Because long-term live imaging requires using low laser power to avoid photobleaching and phototoxicity, a strongly expressing transgenic is highly recommended. This protocol facilitates the visualization of the dynamic processes in vivo, including immune cell migration, host pathogen interaction, and cell death.

This protocol describes a technique for visualizing macrophage behavior and death in embryonic zebrafish during Mycobacterium marinum infection. Steps for the preparation of bacteria, infection of the embryos, and intravital microscopy are included. This technique may be applied to the observation of cellular behavior and death in similar scenarios involving infection or sterile inflammation.

Visualización de la muerte de células líticas de macrófagos durante la infección micobacteriana en embriones de pez cebra a través de la microscopía intravital

Zebrafish is an excellent model organism for studying innate immune cell behavior due to its transparent nature and reliance solely on its innate immune ...

Visualization of Inflammatory Caspases Induced Proximity in Human Monocyte-Derived Macrophages

Inflammatory caspases include caspase-1, -4, -5, -11, and -12 and belong to the subgroup of initiator caspases. Caspase-1 is required to ensure correct regulation of inflammatory signaling and is activated by proximity-induced dimerization following recruitment to inflammasomes. Caspase-1 is abundant in the monocytic cell lineage and induces maturation of the pro-inflammatory cytokines interleukin (IL)-1&#946; and IL-18 to active secreted molecules. The other inflammatory caspases, caspase-4 and -5 (and their murine homolog caspase-11) promote IL-1&#946; release by inducing pyroptosis. Caspase Bimolecular Fluorescence Complementation (BiFC) is a tool used to measure inflammatory caspase induced proximity as a readout of caspase activation. The caspase-1, -4, or -5 prodomain, which contains the region that binds to the inflammasome, is fused to non-fluorescent fragments of the yellow fluorescent protein Venus (Venus-N [VN] or Venus-C [VC]) that associate to reform the fluorescent Venus complex when the caspases undergo induced proximity. This protocol describes how to introduce these reporters into primary human monocyte-derived macrophages (MDM) using nucleofection, treat the cells to induce inflammatory caspase activation, and measure caspase activation using fluorescence and confocal microscopy. The advantage of this approach is that it can be used to identify the components, requirements, and localization of the inflammatory caspase activation complex in living cells. However, careful controls need to be considered to avoid compromising cell viability and behavior. This technique is a powerful tool for the analysis of dynamic caspase interactions at the inflammasome level as well as for the interrogation of the inflammatory signaling cascades in living MDM and monocytes derived from human blood samples.

This protocol describes the workflow to obtain monocytes-derived macrophages (MDM) from human blood samples, a simple method to efficiently introduce inflammatory caspase Bimolecular Fluorescence Complementation (BiFC) reporters into human MDM without compromising cell viability and behavior, and an imaging-based approach to measure inflammatory caspase activation in living cells.

Visualización de la proximidad inducida por caspasas inflamatorias en macrófagos derivados de monocitos humanos

Inflammatory caspases include caspase-1, -4, -5, -11, and -12 and belong to the subgroup of initiator caspases. Caspase-1 is required to ensure correct ...

Visualizing the Early Stages of Phagocytosis

The mammalian body is equipped with various layers of mechanisms that help to defend itself from pathogen invasions. Professional phagocytes of the immune system &#8212; such as neutrophils, dendritic cells, and macrophages &#8212; retain the innate ability to detect and clear such invading pathogens through phagocytosis1. Phagocytosis involves choreographed events of membrane reorganization and actin remodeling at the cell surface2,3. Phagocytes successfully internalize and eradicate foreign molecules only when all stages of phagocytosis are fulfilled. These steps include recognition and binding of the pathogen by pattern recognition receptors (PRRs) residing at the cell surface, formation of phagocytic cup through actin-enriched membranous protrusions (pseudopods) to surround the particulate, and scission of the phagosome followed by phagolysosome maturation that results in the killing of the pathogen3,4.
Imaging and quantification of various stages of phagocytosis is instrumental for elucidating the molecular mechanisms of this cellular process. The present manuscript reports methods to study the different phases of phagocytosis. We describe a microscope-based approach to visualize and quantify the binding, phagocytic cup formation, and the internalization of particulate by phagocytes. As phagocytosis occurs when innate receptors on phagocytic cells encounter ligands on a target particle bigger than 0.5 &#181;m, the assays we present here comprise the use of pathogenic fungi Candida albicans and other particulates such as zymosan and IgG-coated beads.

Here we describe a microscope-based technique to visualize and quantify the early cascades of events during phagocytosis of pathogens such as the fungi Candida albicans and particulates that are larger than 0.5 &#181;m including zymosan and IgG-coated beads.

La visualización de las primeras etapas de la fagocitosis

The mammalian body is equipped with various layers of mechanisms that help to defend itself from pathogen invasions. Professional phagocytes of the immune ...

Biología

Live Fluorescence, Inverse Imaging of Cell Ruffling, and Macropinocytosis

Macropinocytosis is a highly conserved but still incompletely understood process that is essential for the uptake and ingestion of fluid, fluid-phase nutrients and other material in cells. The dramatic extension of cell surface ruffles, their closure to form macropinosomes, and the maturation of internalized macropinosomes are key events in this pathway that can be difficult to capture using conventional confocal imaging based on tracking a bolus of fluorescent cargo. Fluorescent dextrans are commonly used experimentally as fluid phase markers for macropinosomes and for other endocytic pathways. A method the lab has adopted to optimize the imaging of dextran uptake involves using live imaging of cells bathed in high concentrations of fluorescent dextran in the medium, with the unlabeled cells appearing in relief (as black). The cell ruffles are highlighted to visualize ruffle closure, and internalized macropinosomes appear as fluorescent vacuoles in the cell interior. This method is optimal for visualizing macropinosome features and allows for easy segmentation and quantification. This paper describes dual-labeling of pathways with different sized dextrans and the co-expression of lipid probes and fluorescent membrane proteins to demark macropinosomes and other endosomes. The detection of internalized dextran at an ultrastructural level using correlative light and electron microscopy (CLEM) is also demonstrated. These cell processes can be imaged using multiple live imaging modalities, including in 3D. Taken together, these approaches optimize macropinosome imaging for many different settings and experimental systems.

<meta charset="utf8"></head><body>Fluorescencia en vivo, imágenes inversas de agitación celular y macropinocitosis

This protocol demonstrates dextran imaging in live cells using continuous uptake and inverse images to optimize visualization of ruffling, macropinosome maturation, and analysis of dextran and other cell labelings.

Fluorescencia en vivo, imágenes inversas de agitación celular y macropinocitosis

Macropinocytosis is a highly conserved but still incompletely understood process that is essential for the uptake and ingestion of fluid, fluid-phase ...

La visualización no lítico exocitosis de

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