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>
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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. 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The authors have nothing to disclose.

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

12.6K Görüntüleme.  Stony Brook University. 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. 