This research was supported in part by NIH awards 5T32AI07506, 5R01AI033774, 5R37AI033142, 5R01AI052733.

All animal work was done in accordance with regulations and guidelines of the Institute for Animal Studies at Albert Einstein College of Medicine.
1. Growth Conditions of C. neoformans H99 (Serotype A)
<ol>
	<li>Grow individual C. neoformans (Cn) colonies on Sabouraud agar plates.</li>
	<li>One day prior to the experiment, select one colony and inoculate 10 ml of Sabouraud broth.</li>
	<li>Allow culture to grow overnight at 37 &#176;C shaking at a speed of 250 rpm.</li>
</o...

<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>

The authors declare that we have no competing financial interests or other conflicts of interest.

Here we have described a method by which fungal-macrophage interactions can be recorded and analyzed in real time over a 24 hr period. Our lab has used this protocol to study many of the temporal aspects of non-lytic exocytosis and will continue to use real-time microscopy to ascertain the morphological components that surround this process.
For this technique to yield ideal results, special attention should be given to certain steps in the protocol. The cell density that is plated the night b...

The stages of a fungal infection between cryptococcal cells and macrophages are well documented 1-3. After yeast cells are ingested by macrophages, a variety of interactions may occur: the macrophage may lyse releasing its fungal load into the extracellular space, or it could control the infection by keeping the yeast cells within the confines of its cellular membrane 4. However, several years ago a new outcome was described independently by two groups: non-lytic exocytosis, a process in which a macrophage expunged some or all of the cryptococcal cells into the surrounding environment or a neighboring cell and both host and pathogen remain viable 5-8. Several studies have attempted to understand the molecular mechanisms behind this interaction but we still do not have a full grasp on what drives this phenomenon.
The capability to capture images in real-time and then subsequently analyze multiple infected macrophages allows one to answer many questions about the physical properties surrounding non-lytic exocytosis in regards to timing, spatial capacity, change in morphology and even stress of macrophages during a fungal infection. By allowing the cells to be housed in an environment that is comparable to that of an incubator, we can glimpse the dynamic nature of macrophage-fungal cell interactions. Researchers have used this technique to study various components of this process. The role of the phagosome in this process was made apparent using fluorescent staining and actin blocking agents 9, while another group used this method to show that non-lytic exocytosis was blocked in cells that have had the WASH nucleating protein domains deleted 10. The effect of cytokine signaling has also been ascertained using real-time microscopy 11. This process is not limited to C. neoformans as it has also been observed with Candida albicans, another fungal pathogen that has the capability to infect macrophages 12. These findings are examples of how this method can provide a wealth of information to an area we know so little about.

<table border="0" cellpadding="0" cellspacing="0" width="976">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:359px;">Sabouraud Dextrose Agar</td>
			<td style="width:183px;">BD</td>
			<td style="width:227px;">DF0109-17-1</td>
			<td style="width:207px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sabouraud Dextrose Broth</td>
			<td>BD</td>
			<td>DF0382-17-9</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dubelcco&#39;s Modified Eagle&#39;s Medium(DMEM)</td>
			<td>Corning Cellgro</td>
			<td>10-013-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal Calf Serum ( FCS)&#160;</td>
			<td>Atlanta Biologicals</td>
			<td>S12450</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NCTC 109</td>
			<td>Invitrogen</td>
			<td>21340-039</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin-Streptomycin</td>
			<td>Gibco</td>
			<td>15140-122</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HEPES Buffer</td>
			<td>Corning Cellgro</td>
			<td>25-060-Cl</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glutamax</td>
			<td>Invitrogen</td>
			<td>35050-061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Non-essential Amino Acids</td>
			<td>Corning Cellgro</td>
			<td>25-025-Cl</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2-Mercaptoethanol</td>
			<td>Invitrogen</td>
			<td>21985-023</td>
			<td>Toxic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3003 Tissue Culture Petri Dishes&#160;</td>
			<td>Fisher Scientific&#160;</td>
			<td>08772E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CellStripper</td>
			<td>Corning Cellgro</td>
			<td>25-056-Cl</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mat-tek Glass Bottom Culture Dishes</td>
			<td>MatTek</td>
			<td>P35GC-1.5-14-C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LPS</td>
			<td>Sigma</td>
			<td>L3137</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse IFN-g</td>
			<td>Roche</td>
			<td>NC 9222016</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">mAb 18B7</td>
			<td colspan="2">&#160;&#160;&#160;&#160;&#160;&#160; Non-commerical antibody produced in our lab</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">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

Many aspects of the infection of macrophages by Cryptococcus neoformans have been extensively studied and well defined. However, one particular interaction that is not clearly understood is non-lytic exocytosis. In this process, yeast cells are released into the extracellular space by a poorly understood mechanism that leaves both the macrophage and Cn viable. Here, we describe how to follow a large number of individually infected macrophages for a 24 hr infection period by time-lapsed microscopy. Infected macrophages are housed in a heating chamber with a CO2 atmosphere attached to a microscope that provides the same conditions as a cell-culture incubator. Live digital microscopy can provide information about the dynamic interactions between a host and pathogen that is not available from static images. Being able to visualize each infected cell can provide clues as to how macrophages handle fungal infections, and vice versa. This technique is a powerful tool in studying the dynamics that are behind a complex phenomenon.

The images that this technique produces can be analyzed in a variety of ways to collect information surrounding what happens after cells have phagocytosed C. neoformans. As seen in Figure 1, there are approximately 100 macrophages that are either infected or uninfected. Each one of these macrophages gives the viewer an opportunity to study host-pathogen interactions on a very microscopic level. As Figures 2 and 3 show, there are different outcomes that can occur...

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

We describe how to visualize macrophage-C. neoformans (Cn) interactions in real time, with specific emphasis on the process of non-lytic exocytosis using digital light microscopy. Using this technique individually infected macrophages can be studied to ascertain various aspects of this phenomenon.

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

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

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Immunology and Infection

11.7K 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. 