Name: macrophage cholesterol depletion and its effect on the phagocytosis of cryptococcus neoformans
Uploaded: 2014-12-19T15:00:00
Description: Watch this Scientific Journal Video about Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans at JoVE.com

This work was supported by NIH grants AI56168, AI71142, AI87541 and AI100631 to MDP. Maurizio Del Poeta is Burroughs Wellcome Investigator in Infectious Diseases.

1. Cholesterol Depletion of J774A.1 Cells with M&#946;CD
<ol>
	<li>In a sterile biosafety cabinet, seed 105 J774A.1 macrophage-like cells per well on a 96-well cell culture plate in 200 &#956;l of Dulbecco&#8217;s Modified Eagle Medium (DMEM) supplemented with 10% fetal bovine serum (FBS) and 1% penicillin/streptomycin (P/S). Incubate at 37 &#176;C and 5% CO2 O/N.</li>
	<li>Remove media from the cell monolayer and wash the cells twice with 1x phosphate buffered saline (PBS) that has been filtered ...

<ol>
	<li>Sarantis, H., Grinstein, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subversion+of+phagocytosis+for+pathogen+survival.">Subversion of phagocytosis for pathogen survival.</a> Cell Host &amp; Microbe. 12 (4), 419-431 (2012).</li><li>Rougerie, P., Miskolci, V., Cox, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+Of+Membrane+Structures+During+Phagocytosis+And+Chemotaxis+Of+Macrophages:+Role+And+Regulation+Of+The+Actin+Cytoskeleton.">Generation Of Membrane Structures During Phagocytosis And Chemotaxis Of Macrophages: Role And Regulation Of The Actin Cytoskeleton.</a> Immunological Reviews. 256 (1), 222-239 (1111).</li><li>Liu, T., Perlin, D. S., Xue, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+Mechanisms+Of+Cryptococcal+Meningitis.">Molecular Mechanisms Of Cryptococcal Meningitis.</a> Virulence. 3, 173 (2012).</li><li>Abadi, J., Pirofski, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Antibodies+Reactive+With+The+Cryptococcal+Capsular+Polysaccharide+Glucuronoxylomannan+Are+Present+In+Sera+From+Children+With+And+Without+Human+Immunodeficiency+Virus+Infection.">A Antibodies Reactive With The Cryptococcal Capsular Polysaccharide Glucuronoxylomannan Are Present In Sera From Children With And Without Human Immunodeficiency Virus Infection.</a> The Journal Of Infectious Diseases. 180 (3), 915-919 (1999).</li><li>Kechichian, T. B., Shea, J., Del Poeta, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Depletion+Of+Alveolar+Macrophages+Decreases+The+Dissemination+Of+A+Glucosylceramide-Deficient+Mutant+Of+Cryptococcus+Neoformans+In+Immunodeficient+Mice.">Depletion Of Alveolar Macrophages Decreases The Dissemination Of A Glucosylceramide-Deficient Mutant Of Cryptococcus Neoformans In Immunodeficient Mice.</a> Infection And Immunity. 75 (10), 4792-4798 (2007).</li><li>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=Cryptococci+At+The+Brain+Gate:+Break+And+Enter+Or+Use+A+Trojan+Horse.">Cryptococci At The Brain Gate: Break And Enter Or Use A Trojan Horse.</a> The Journal Of Clinical Investigation. 120 (5), 1389-1692 (1172).</li><li>Chr&#233;tien, F., 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=Pathogenesis+Of+Cerebral+Cryptococcus+Neoformans+Infection+After+Fungemia.">Pathogenesis Of Cerebral Cryptococcus Neoformans Infection After Fungemia.</a> The Journal Of Infectious Diseases. 186 (4), 522-530 (2002).</li><li>Luberto, C., Martinez-Mari&#241;o, B., 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=Identification+Of+App1+As+A+Regulator+Of+Phagocytosis+And+Virulence+Of+Cryptococcus+Neoformans.">Identification Of App1 As A Regulator Of Phagocytosis And Virulence Of Cryptococcus Neoformans.</a> The Journal Of Clinical Investigation. 112 (7), 1080-1094 (1172).</li><li>Mcquiston, T. J., Williamson, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Paradoxical+Roles+Of+Alveolar+Macrophages+In+The+Host+Response+To+Cryptococcus+Neoformans.">Paradoxical Roles Of Alveolar Macrophages In The Host Response To Cryptococcus Neoformans.</a> Journal Of Infection And Chemotherapy: Official Journal Of The Japan Society Of Chemotherapy. 18 (1), 1-9 (2012).</li><li>Garc&#237;a-Rodas, R., Zaragoza, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catch+Me+If+You+Can:+Phagocytosis+And+Killing+Avoidance+By+Cryptococcus+Neoformans.">Catch Me If You Can: Phagocytosis And Killing Avoidance By Cryptococcus Neoformans.</a> FEMS Immunology And Medical Microbiology. 64 (2), 147-161 (2012).</li><li>Coelho, C., Bocca, A. 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K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+Of+Cholesterol+In+The+Formation+And+Nature+Of+Lipid+Rafts+In+Planar+And+Spherical+Model+Membranes.">Role Of Cholesterol In The Formation And Nature Of Lipid Rafts In Planar And Spherical Model Membranes.</a> Biophysical Journal. 86 (5), 2965-2979 (2004).</li><li>Brown, D. A., London, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functions+Of+Lipid+Rafts+In+Biological+Membranes.">Functions Of Lipid Rafts In Biological Membranes.</a> Annual Review Of Cell And Developmental Biology. 14, 111-136 (1998).</li><li>Simons, K., Toomre, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipid+Rafts+And+Signal+Transduction+Nature+Reviews.">Lipid Rafts And Signal Transduction Nature Reviews.</a> Molecular Cell Biology. 1 (1), 31-39 (2000).</li><li>Ilangumaran, S., Hoessli, D. 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In working with this protocol it is important to obtain accurate cell counts when plating mammalian cells and opsonizing C. neoformans cells. This minimizes variation between trials and ensures an accurate 1:1 target to effector ratio throughout the study. It is also critical to coordinate the timing of the cholesterol depletion and infection to prevent the opsonized yeast cells or treated macrophage cells from resting at RT in between the procedures. Long waiting periods could lead to loss of antibody opsonizat...

Phagocytosis is a process by which extracellular entities are internalized by host cells. It is a key weapon in the immune system&#8217;s arsenal to defend against pathogens, but the process may often be subverted by pathogens to allow for internalization and spreading throughout the body1. Phagocytosis is mediated by several signaling events that result in attachment and engulfment via rearrangements of the host cell&#8217;s cytoskeleton. &#8216;Professional&#8217; phagocytes are able to recognize and bind to opsonins on the surface of the invading pathogen to signal for attachment and the formation of lamellipodia, which engulf the pathogen and form a phagosome2. Among the so-called &#8216;professional&#8217; phagocytes are macrophages. Macrophages are highly specialized cells that carry out protective functions that include seeking out and eliminating disease causing agents, repairing damaged tissues, and mediating inflammation, most of these through the process of phagocytosis1,2.
Cryptococcus neoformans is a species of pathogenic yeast that causes a serious disease known as Cryptococcosis. Cryptococcus spores are inhaled by the host and result in a pulmonary infection that is usually asymptomatic. It is thought that exposure is extremely prevalent; a sample of 61 children from the Pediatric Infectious Diseases Clinic at the Bronx-Lebanon Hospital Center found that all those surveyed had antibodies to&#160;the cryptococcal polysaccharide glucuronoxylomannan and other studies have shown prevalence in both human immunodeficiency virus (HIV) uninfected and infected adults3,4. Alveolar macrophages are the first line of response to the pulmonary infection and in most cases successfully clear the pathogen. However, in immunocompromised individuals (e.g., HIV and AIDS patients) the yeast is able to survive within the macrophages. In these cases, the macrophages can serve as a niche for the replication of the pathogen and may facilitate its dissemination to the central nervous system (CNS) where the disease becomes fatal5&#8211;8. It is thought that macrophages may even deliver the yeast directly into the meninges, helping the yeast to cross the blood brain barrier via the &#8220;Trojan horse&#8221; model3,9&#8211;11. Thus, it is important to understand the process of phagocytosis and the factors that affect it, especially in cryptococcal infections.
Previous work in other pathogen systems point to cholesterol and lipid rafts formed by cholesterol as having an important role to play in phagocytosis12&#8211;15. Cholesterol is the most abundant lipid species in mammalian cells and comprises 25 - 50% of the mammalian cell membrane16. It has been found to play a role in modulating the biophysical properties of membranes by changing their rigidity17. Cholesterol and sphingolipids together form lipid microdomains within the membrane known as lipid rafts. Lipid rafts have been found to be involved in the formation of caveolae, as well as providing an isolated domain for certain types of signaling16&#8211;18. Due to their small size, it is difficult to study lipid rafts in vivo. One useful way to study the role of lipid rafts is to alter their constituents. Methyl-&#946;-cyclodextrin (M&#946;CD) is a compound that has been found to deplete cholesterol from mammalian membranes and is commonly used to study the role of lipid rafts18.
In this protocol, we present a method to deplete cholesterol from host cell membranes and quantify the effect of the depletion on the ability of the host cells to phagocytose C. neoformans in vitro. This procedure makes use of cell culture techniques on an immortalized macrophage like cell line (J774A.1) as a model for infection. Cholesterol depletion was accomplished by exposure to M&#946;CD, which has a hydrophobic core specific to the size of sterols and is able to act as a sink for cholesterol to draw it out of the membrane19. Cholesterol depletion was measured quantitatively using a commercially available kit and qualitatively using a modified Bligh-Dyer lipid extraction followed by thin layer chromatography (TLC)20. Phagocytosis was measured by infecting the cell line with a culture of opsonized yeast mixed with a cocktail of interferon-&#947; and lipopolysaccharide for activating the macrophages. Cryptococcus was opsonized using a glucuronoxylomannan (GXM) antibody21&#8211;23. Staining and microscopy experiments allowed for visualization of the cells and calculation of the phagocytic index to assess the degree of phagocytosis. Taken together, this protocol describes a basic method that integrates the alteration of lipid composition with a physiological process.

<table border="0" cellpadding="0" cellspacing="0" width="622">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Name of Reagent/ Equipment</td>
			<td style="width:120px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments/Description</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Class II type A2 Biosafety Cabinet</td>
			<td style="width:120px;">Labconco</td>
			<td style="width:119px;">3460009</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:216px;">J774A.1 cell line</td>
			<td style="width:120px;">ATCC</td>
			<td style="width:119px;">TIB-67</td>
			<td style="width:167px;">Arrives Frozen. See ATCC instructions for culturing.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dulbecco&#8217;s Modified Eagle Medium</td>
			<td style="width:120px;">Gibco</td>
			<td style="width:119px;">11995-065</td>
			<td style="width:167px;">Store at 4 &#176;C and warm to 37 &#176;C prior to use</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">HI Fetal Bovine Serum Performance Plus</td>
			<td style="width:120px;">Gibco</td>
			<td style="width:119px;">10082-147</td>
			<td style="width:167px;">Keep frozen at -20 &#176;C and thaw before adding to DMEM</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Penicillin-Streptomycin (10,000 U/mL)</td>
			<td style="width:120px;">Gibco</td>
			<td style="width:119px;">15140-122</td>
			<td style="width:167px;">Used to suplement DMEM</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Isotemp Cell culture incubator</td>
			<td style="width:120px;">Fisher Scientific</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Model # 3530</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">96-Well culture dish</td>
			<td style="width:120px;">Corning Inc. Costar</td>
			<td style="width:119px;">3595</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">10x Phosphate Buffered Saline</td>
			<td style="width:120px;">Fisher Scientific BioReagents</td>
			<td style="width:119px;">BP3994</td>
			<td style="width:167px;">Dilute to 1x and filter or autoclave prior to use.</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Methyl-&#946;-Cyclodextrin</td>
			<td style="width:120px;">Sigma Life Science</td>
			<td style="width:119px;">C4555-10G</td>
			<td style="width:167px;">Dissolve in 1x PBS to make solutions of 10mM and 30mM concentrations</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Orbital Shaker</td>
			<td style="width:120px;">Labline</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">Amplex Red Cholesterol Assay Kit</td>
			<td style="width:120px;">Life Technologies Molecular Probes</td>
			<td style="width:119px;">A12216</td>
			<td style="width:167px;">All reagents for Cholesterol Assay are contained within the kit. Follow Manufacturer instructions.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">96-Well Black Assay plate</td>
			<td style="width:120px;">Corning Inc. Costar</td>
			<td style="width:119px;">3603</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">FilterMax microplate reader</td>
			<td style="width:120px;">Molecular Devices</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Model F5</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">TLC Chamber</td>
			<td style="width:120px;">Sigma-Aldrich</td>
			<td style="width:119px;">Z126195-1EA</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Chloroform</td>
			<td style="width:120px;">Sigma-Aldrich</td>
			<td style="width:119px;">650498-4L</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Methanol</td>
			<td style="width:120px;">Sigma-Aldrich</td>
			<td style="width:119px;">34860-2L-R</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">TLC Paper</td>
			<td style="width:120px;">Whatman</td>
			<td style="width:119px;">3030917</td>
			<td style="width:167px;">Cut down to size needed for TLC tank</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Fume Hood</td>
			<td style="width:120px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Any fume hood that complies with AIHA/ANSI Standards&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">6-Well Plate</td>
			<td style="width:120px;">Corning Inc. Costar</td>
			<td style="width:119px;">3506</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Trypsin-EDTA</td>
			<td style="width:120px;">Gibco</td>
			<td style="width:119px;">25300-054</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Cell Scraper</td>
			<td style="width:120px;">Corning Inc. Costar</td>
			<td style="width:119px;">3010</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Hemocytometer&#160;</td>
			<td style="width:120px;">Hausser Scientific</td>
			<td style="width:119px;">1490</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Centrifuge</td>
			<td style="width:120px;">Beckman Coulter</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Model Alegra x-30R</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Votex Mixer</td>
			<td style="width:120px;">Fisher Scientific</td>
			<td style="width:119px;">12-812</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Balance</td>
			<td style="width:120px;">Mettler Toledo</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Model # MS104S Meaures down to .1 mg</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Glass Pasteur Pipette</td>
			<td style="width:120px;">Fisherbrand</td>
			<td style="width:119px;">13-678-20A</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Cholesterol</td>
			<td style="width:120px;">Avanti Polar Lipids</td>
			<td style="width:119px;">700000</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">SpeedVac Concentrator</td>
			<td style="width:120px;">Thermo Scientific</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Model # SPD2010&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Petroleum Ether</td>
			<td style="width:120px;">Fisher Scientific</td>
			<td style="width:119px;">E139-1&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Diethyl Ether</td>
			<td style="width:120px;">Sigma-Aldrich</td>
			<td style="width:119px;">309966&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Acetic Acid</td>
			<td style="width:120px;">Sigma-Aldrich</td>
			<td style="width:119px;">320099</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">TLC Silica Gel 60 with concentrating zone</td>
			<td style="width:120px;">Analytical Chromatograhy Millipore</td>
			<td style="width:119px;">1.11845.0001</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Iodine Chips</td>
			<td style="width:120px;">Sigma-Aldrich</td>
			<td style="width:119px;">376558-50G</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Sulfuric Acid</td>
			<td style="width:120px;">Sigma-Aldrich</td>
			<td style="width:119px;">320501&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Manganese Chloride</td>
			<td style="width:120px;">Sigma-Aldrich</td>
			<td style="width:119px;">244589</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">UVP EC3 Imaging System</td>
			<td style="width:120px;">Ultra-Violet Products Ltd.</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Use the Vision Works LS software for densitometry analysis</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Glass Bottom Confocal Dish</td>
			<td style="width:120px;">MatTek</td>
			<td style="width:119px;">P35G-1.5-10C</td>
			<td>www.glassbottomdishes.com</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Cryptococcus neoformans (H99)</td>
			<td style="width:120px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Obtained from Duke University Medical Center</td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">YNB</td>
			<td style="width:120px;">BD</td>
			<td style="width:119px;">239210</td>
			<td style="width:167px;">See manufacturer for preparation instructions. Use a Glucose concentration of 20 g/L.</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Lipopolysaccharide</td>
			<td style="width:120px;">Sigma</td>
			<td style="width:119px;">L4391-1MG</td>
			<td style="width:167px;">Dissolve in 1x PBS to make 1mg/mL stock. Store at -20 &#176;C.</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Interferon gamma</td>
			<td style="width:120px;">Sigma</td>
			<td style="width:119px;">I4777</td>
			<td style="width:167px;">Dissolve in 1x PBS to make .1 mg/mL stock solution</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Glucuronoxylomannan antibody (anti-GXM)</td>
			<td style="width:120px;"></td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Gift from Arturo Casadevall&#39;s Lab concentration is 1.98 mg/mL</td>
		</tr>
		<tr height="168">
			<td height="168" style="height:168px;width:216px;">Giemsa</td>
			<td style="width:120px;">MP Biomedicals</td>
			<td style="width:119px;">194591</td>
			<td style="width:167px;">Dissolve .8 g of Giemsa in 25 mL of Glycerol and heat to 60 &#176;C for 1 hour. Add 25 mL of methanol to the solution and allow to age at room temperature for at least 1 month.</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Microscope</td>
			<td style="width:120px;">Zeiss</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Observer.D1 microscope with AxioCam MRm for taking images</td>
		</tr>
	</tbody>
</table>

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.

Cholesterol Depletion
Analysis of the supernatant reserved in step 1.3 of the protocol by following the manufacturer&#8217;s instructions in the Amplex Red Cholesterol Assay kit yields an elevated concentration of cholesterol in M&#946;CD treated sample as compared to the 1x PBS control. Depending on cell type and M&#946;CD concentration used cholesterol depletion may vary. For J774 treated with 10 mM M&#946;CD, a depletion of approximately 50% was observed. Depletion can be calculated using valu...

Watch this Scientific Journal Video about Macrophage Cholesterol Depletion and Its Effect on the Phagocytosis of Cryptococcus neoformans at JoVE.com

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.

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 ...

macrophage-cholesterol-depletion-its-effect-on-phagocytosis

Research

JoVE Journal

Immunology and Infection

Depletion of Specific Cell Populations by Complement Depletion

The purification of immune cell populations is often required in order to study their unique functions. In particular, molecular approaches such as real-time PCR and microarray analysis require the isolation of cell populations with high purity. Commonly used purification strategies include fluorescent activated cell sorting (FACS), magnetic bead separation and complement depletion. Of the three strategies, complement depletion offers the advantages of being fast, inexpensive, gentle on the cells and a high cell yield. The complement system is composed of a large number of plasma proteins that when activated initiate a proteolytic cascade culminating in the formation of a membrane-attack complex that forms a pore on a cell surface resulting in cell death1. The classical pathway is activated by IgM and IgG antibodies and was first described as a mechanism for killing bacteria. With the generation of monoclonal antibodies (mAb), the complement cascade can be used to lyse any cell population in an antigen-specific manner. Depletion of cells by the complement cascade is achieved by the addition of complement fixing antigen-specific antibodies and rabbit complement to the starting cell population. The cells are incubated for one hour at 37&deg;C and the lysed cells are subsequently removed by two rounds of washing. MAb with a high efficiency for complement fixation typically deplete 95-100% of the targeted cell population. Depending on the purification strategy for the targeted cell population, complement depletion can be used for cell purification or for the enrichment of cell populations that then can be further purified by a subsequent method.

To effectively study the function of immune cell populations their purification is often required. Complement depletion is a fast and inexpensive technique for the isolation of immune cell populations with high purity.

The purification of immune cell populations is often required in order to study their unique functions.  In particular, molecular approaches such as ...

Depletion and Reconstitution of Macrophages in Mice

Macrophages are critical players in the innate immune response to infectious challenge or injury, initiating the innate immune response and directing the acquired immune response. Macrophage dysfunction can lead to an inability to mount an appropriate immune response and as such, has been implicated in many disease processes, including inflammatory bowel diseases. Macrophages display polarized phenotypes that are broadly divided into two categories. Classically activated macrophages, activated by stimulation with IFN&gamma; or LPS, play an essential role in response to bacterial challenge whereas alternatively activated macrophages, activated by IL-4 or IL-13, participate in debris scavenging and tissue remodeling and have been implicated in the resolution phase of inflammation. During an inflammatory response in vivo, macrophages are found amid a complex mixture of infiltrating immune cells and may participate by exacerbating or resolving inflammation. To define the role of macrophages in situ in a whole animal model, it is necessary to examine the effect of depleting macrophages from the complex environment. To ask questions about the role of macrophage phenotype in situ, phenotypically defined polarized macrophages can be derived ex vivo, from bone marrow aspirates and added back to mice, with or without prior depletion of macrophages. In the protocol presented here clodronate-containing liposomes, versus PBS injected controls, were used to deplete colonic macrophages during dextran sodium sulfate (DSS)-induced colitis in mice. In addition, polarized macrophages were derived ex vivo and transferred to mice by intravenous injection. A caveat to this approach is that clodronate-containing liposomes deplete all professional phagocytes, including both dendritic cells and macrophages so to ensure the effect observed by depletion is macrophage-specific, reconstitution of phenotype by adoptive transfer of macrophages is necessary. Systemic macrophage depletion in mice can also be achieved by backcrossing mice onto a CD11b-DTR background, which is an excellent complementary approach. The advantage of clodronate-containing liposome-mediated depletion is that it does not require the time and expense involved in backcrossing mice and it can be used in mice regardless of the background of the mice (C57BL/6, BALB/c, or mixed background).

Macrophages play a central role in homeostasis and pathology in many tissues. The protocol presented here describes methods for depleting macrophages in vivo, deriving polarized macrophages from bone marrow aspirates, and adoptively transferring macrophages into mice. These techniques allow determination of the role that polarized macrophages play in health and disease.

Macrophages are critical players in the innate  immune response to infectious challenge or injury, initiating the innate immune  response and directing ...

The Synergistic Effect of Visible Light and Gentamycin on Pseudomona aeruginosa Microorganisms

Recently there were several publications on the bactericidal effect of visible light, most of them claiming that blue part of the spectrum (400 nm-500 nm) is responsible for killing various pathogens1-5. The phototoxic effect of blue light was suggested to be a result of light-induced reactive oxygen species (ROS) formation by endogenous bacterial photosensitizers which mostly absorb light in the blue region4,6,7. There are also reports of biocidal effect of red and near infra red8 as well as green light9.
In the present study, we developed a method that allowed us to characterize the effect of high power green (wavelength of 532 nm) continuous (CW) and pulsed Q-switched (Q-S) light on Pseudomonas aeruginosa. Using this method we also studied the effect of green light combined with antibiotic treatment (gentamycin) on the bacteria viability. P. aeruginosa is a common noscomial opportunistic pathogen causing various diseases. The strain is fairly resistant to various antibiotics and contains many predicted AcrB/Mex-type RND multidrug efflux systems10.
The method utilized free-living stationary phase Gram-negative bacteria (P. aeruginosa strain PAO1), grown in Luria Broth (LB) medium exposed to Q-switched and/or CW lasers with and without the addition of the antibiotic gentamycin. Cell viability was determined at different time points. The obtained results showed that laser treatment alone did not reduce cell viability compared to untreated control and that gentamycin treatment alone only resulted in a 0.5 log reduction in the viable count for P. aeruginosa. The combined laser and gentamycin treatment, however, resulted in a synergistic effect and the viability of P. aeruginosa was reduced by 8 log's.
The proposed method can further be implemented via the development of catheter like device capable of injecting an antibiotic solution into the infected organ while simultaneously illuminating the area with light.

The Synergistic Effect of Visible Light and Gentamycin on Pseudomona aeruginosa Microorganisms

We show that a developed biomedical device involving continuous or pulsed visible laser based treatment that is combined with antibiotic treatment (gentamycin), results in a statistically significant synergistic effect leading to a reduction in the viability of P. aeruginosa PAO1, by 8 log's compared to antibiotic treatment alone.

Recently there were several publications on the  bactericidal effect of visible light, most of them claiming that blue part of  the spectrum (400 nm-500 ...

Using Click Chemistry to Measure the Effect of Viral Infection on Host-Cell RNA Synthesis

Many RNA viruses have evolved the ability to inhibit host cell transcription as a means to circumvent cellular defenses. For the study of these viruses, it is therefore important to have a quick and reliable way of measuring transcriptional activity in infected cells. Traditionally, transcription has been measured either by incorporation of radioactive nucleosides such as 3H-uridine followed by detection via autoradiography or scintillation counting, or incorporation of halogenated uridine analogs such as 5-bromouridine (BrU) followed by detection via immunostaining. The use of radioactive isotopes, however, requires specialized equipment and is not feasible in a number of laboratory settings, while the detection of BrU can be cumbersome and may suffer from low sensitivity.
The recently developed click chemistry, which involves a copper-catalyzed triazole formation from an azide and an alkyne, now provides a rapid and highly sensitive alternative to these two methods. Click chemistry is a two step process in which nascent RNA is first labeled by incorporation of the uridine analog 5-ethynyluridine (EU), followed by detection of the label with a fluorescent azide. These azides are available as several different fluorophores, allowing for a wide range of options for visualization.
This protocol describes a method to measure transcriptional suppression in cells infected with the Rift Valley fever virus (RVFV) strain MP-12 using click chemistry. Concurrently, expression of viral proteins in these cells is determined by classical intracellular immunostaining. Steps 1 through 4 detail a method to visualize transcriptional suppression via fluorescence microscopy, while steps 5 through 8 detail a method to quantify transcriptional suppression via flow cytometry. This protocol is easily adaptable for use with other viruses.

This method describes the use of click chemistry to measure changes in host cell transcription after infection with the Rift Valley fever virus (RVFV) strain MP-12. Results can be visualized qualitatively via fluorescence microscopy or obtained quantitatively through flow cytometry. This method is adaptable for use with other viruses.

Many RNA viruses have evolved the ability to inhibit host cell transcription as a means to circumvent cellular defenses. For the study of these viruses, ...

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.

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.

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

High Throughput Fluorometric Technique for Assessment of Macrophage Phagocytosis and Actin Polymerization

The goal of fluorometric analysis is to serve as an efficient, cost effective, high throughput method of analyzing phagocytosis and other cellular processes. This technique can be used on a variety of cell types, both adherent and non-adherent, to examine a variety of cellular properties. When studying phagocytosis, fluorometric technique utilizes phagocytic cell types such as macrophages, and fluorescently labeled opsonized particles whose fluorescence can be extinguished in the presence of trypan blue. Following plating of adherent macrophages in 96-well plates, fluorescent particles (green or red) are administered and cells are allowed to phagocytose for varied amounts of time. Following internalization of fluorescent particles, cells are washed with trypan blue, which facilitates extinction of fluorescent signal from bacteria which are not internalized, or are merely adhering to the cell surface. Following the trypan wash, cells are washed with PBS, fixed, and stained with DAPI (nuclear blue fluorescent label), which serves to label nuclei of cells. By a simple fluorometric quantification through plate reading of nuclear (blue) or particle (red/green) fluorescence we can examine the ratio of relative fluorescence units of green:blue and determine a phagocytic index indicative of amount of fluorescent bacteria internalized per cell. The duration of assay using a 96-well method and multichannel pipettes for washing, from end of phagocytosis to end of data acquisition, is less than 45 min. Flow cytometry could be used in a similar manner but the advantage of fluorometry is its high throughput, rapid method of assessment with minimal manipulation of samples and quick quantification of fluorescent intensity per cell. Similar strategies can be applied to non adherent cells, live labeled bacteria, actin polymerization, and essentially any process utilizing fluorescence. Therefore, fluorometry is a promising method for its low cost, high throughput capabilities in the study of cellular processes.

Here we present a protocol to quantify phagocytosis of fluorescent particles by adherent macrophage cell line using a fluorometric method. This method facilitates a high throughput quantification of particle internalization as well as the resulting actin polymerization.

The goal of fluorometric analysis is to serve as an efficient, cost effective, high throughput method of analyzing phagocytosis and other cellular ...

Biolistic Transformation of a Fluorescent Tagged Gene into the Opportunistic Fungal Pathogen Cryptococcus neoformans

The basidiomycete Cryptococcus neoformans, an invasive opportunistic pathogen of the central nervous system, is the most frequent cause of fungal meningitis worldwide resulting in more than 625,000 deaths per year worldwide.&#160;Although electroporation has been developed for the transformation of plasmids in Cryptococcus, only&#160;biolistic&#160;delivery provides&#160;an effective means to transform&#160;linear&#160;DNA&#160;that can be integrated into the genome by homologous recombination.&#160;
Acetate has been shown to be a major fermentation product during cryptococcal infection, but the significance of this is not yet known.&#160;A bacterial pathway composed of the enzymes xylulose-5-phosphate/fructose-6-phosphate phosphoketolase (Xfp) and acetate kinase (Ack) is one of three potential pathways for acetate production in C. neoformans. Here, we demonstrate the biolistic transformation of a construct, which has the gene encoding Ack fused to the fluorescent tag mCherry, into&#160;C. neoformans. We then confirm integration of the ACK-mCherry fusion into the&#160;ACK&#160;locus.

Biolistic Transformation of a Fluorescent Tagged Gene into the Opportunistic Fungal Pathogen Cryptococcus neoformans

Biolistic transformation is a method used to generate stable integration of DNA into the genome of the opportunistic pathogen Cryptococcus neoformans through homologous recombination. We will demonstrate biolistic transformation of a construct, which has the gene encoding acetate kinase fused to the fluorescent tag mCherry into&#160;C. neoformans.

The basidiomycete Cryptococcus neoformans, an invasive opportunistic pathogen of the central nervous system, is the most frequent cause of fungal ...

RNA Purification from Intracellularly Grown Listeria monocytogenes in Macrophage Cells

Analysis of the transcriptome of bacterial pathogens during mammalian infection is a valuable tool for studying genes and factors that mediate infection. However, isolating bacterial RNA from infected cells or tissues is a challenging task, since mammalian RNA mostly dominates the lysates of infected cells. Here we describe an optimized method for RNA isolation of Listeria monocytogenes bacteria growing within bone marrow derived macrophage cells. Upon infection, cells are mildly lysed and rapidly filtered to discard most of the host proteins and RNA, while retaining intact bacteria. Next, bacterial RNA is isolated using hot phenol-SDS extraction followed by DNase treatment. The extracted RNA is suitable for gene transcription analysis by multiple techniques. This method is successfully employed in our studies of Listeria monocytogenes gene regulation during infection of macrophage cells 1-4. The protocol can be easily modified to study other bacterial pathogens and cell types.

RNA Purification from Intracellularly Grown Listeria monocytogenes in Macrophage Cells

Here we describe a method for bacterial RNA isolation from Listeria monocytogenes bacteria growing inside murine macrophages. This technique can be used with other intracellular pathogens and mammalian host cells.

Analysis of the transcriptome of bacterial pathogens during mammalian infection is a valuable tool for studying genes and factors that mediate infection. ...

Assessment of Antibody-based Drugs Effects on Murine Bone Marrow and Peritoneal Macrophage Activation

Macrophages are phagocytic innate immune cells, which initiate immune responses to pathogens and contribute to healing and tissue restitution. Macrophages are equally important in turning off inflammatory responses. We have shown that macrophages stimulated with intravenous immunoglobulin (IVIg) can produce high amounts of the anti-inflammatory cytokine, interleukin 10 (IL-10), and low levels of pro-inflammatory cytokines in response to bacterial lipopolysaccharides (LPS). IVIg is a polyvalent antibody, primarily immunoglobulin Gs (IgGs), pooled from the plasma of more than 1,000 blood donors. It is used to supplement antibodies in patients with immune deficiencies or to suppress immune responses in patients with autoimmune or inflammatory conditions. Infliximab, a therapeutic anti-tumor necrosis factor alpha (TNF&#945;) antibody, has also been shown to activate macrophages to produce IL-10 in response to inflammatory stimuli. IVIg and other antibody-based biologics can be tested to determine their effects on macrophage activation. This paper describes methods for derivation, stimulation, and assessment of murine bone marrow macrophages activated by antibodies in vitro and murine peritoneal macrophages activated with antibodies in vivo. Finally, we demonstrate the use of western blotting to determine the contribution of specific cell signaling pathways to anti-inflammatory macrophage activity. These protocols can be used with genetically modified mice, to determine the effect of a specific protein(s) on anti-inflammatory macrophage activation. These techniques can also be used to assess whether specific biologics may act by changing macrophages to an IL-10-producing anti-inflammatory activation state that reduces inflammatory responses in vivo. This can provide information on the role of macrophage activation in the efficacy of biologics during disease models in mice, and provide insight into a potential new mechanism of action in people. Conversely, this may caution against the use of specific antibody-based biologics to treat infectious disease, particularly if macrophages play an important role in host defense against that infection.

Antibody-based drugs have revolutionized treatment for inflammatory diseases. In addition to having direct effects on specific targets, antibodies can activate macrophages to become anti-inflammatory. This protocol describes how anti-inflammatory macrophage activation can be assessed in vitro, using mouse bone marrow macrophages, and in vivo, using peritoneal macrophages.

Macrophages are phagocytic innate immune cells, which initiate immune responses to pathogens and contribute to healing and tissue restitution. Macrophages ...

Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans

The polysaccharide capsule of Cryptococcus neoformans is the primary virulence factor and one of the most commonly studied aspects of this pathogenic yeast. Capsule size can vary widely between strains, has the ability to grow rapidly when introduced to stressful or low nutrient conditions, and has been positively correlated with strain virulence. For these reasons, the size of the capsule is of great interest to C. neoformans researchers. The growth of the C. neoformans capsule is induced during phenotypic testing to help understand the effects of different treatments on the yeast or size differences between strains. Here we describe one of the standard methods of capsule induction and compare two accepted methods of staining and measuring capsule diameter: (i) India ink, a negative stain, used in conjunction with conventional light microscopy and (ii) co-staining with fluorescent dyes of both the cell wall and capsule followed by confocal microscopy. Finally, we show how measurement of capsule diameter from India ink-stained samples can be automated using computational image analysis.

Size Matters: Measurement of Capsule Diameter in Cryptococcus neoformans

The polysaccharide capsule is the primary virulence factor in Cryptococcus neoformans, and its size correlates with strain virulence. Capsule diameter measurements are used in phenotypic testing and to gauge therapeutic efficacy. Here a standard method of capsule induction is presented, and two methods of staining and measuring diameter are compared.

The polysaccharide capsule of Cryptococcus neoformans is the primary virulence factor and one of the most commonly studied aspects of this pathogenic ...