Name: quantification of monocyte transmigration and foam cell formation from individuals with chronic inflammatory conditions
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The authors gratefully acknowledge the work of Prof. William Muller and Dr. Clare Westhorpe for their key role in development of earlier iterations of this model. The authors would also like to thank the AMREP Flow Cytometry core for the sorting of monocyte subsets and the Alfred Hospital Infectious Disease Unit clinical research nurses for the recruitment of HIV+ individuals for some studies. The authors gratefully acknowledge the contribution to this work of the Victoria Operational Infrastructure Support Program received by the Burnet Institute. TAA is supported by an RMIT University Vice-Chancellor&#39;s Postdoctoral Fellowship. This work was supported by NHMRC project grant 1108792 awarded to AJ and AH. TK is supported by NIH grants NIH K08AI08272, NIH/NCATS Grant # UL1TR000124.

NOTE: All experiments using human biological samples were performed with ethics approval from the Alfred Hospital Human Ethics Committee, Melbourne. All experiments were performed in Class II Biosafety cabinets unless specified. &#34;Prewarmed&#34; refers to reagents warmed to 37 &#176;C in a waterbath.
1. Preparation of Type I Fibrous Collagen Gels: Day 1
<ol>
	<li>Prepare polymerized collagen gels by sequentially adding and mixing 35.7 mM NaOH, 0.71 x M199, 4.58 mM acetic acid and 1.71 mg/...

<ol>
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J., Geissmann, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monocytes+in+atherosclerosis:+subsets+and+functions.">Monocytes in atherosclerosis: subsets and functions.</a> Nat Rev Cardiol. 7 (2), 77-86 (2010).</li><li>Xu, L., 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=Foamy+Monocytes+Form+Early+and+Contribute+to+Nascent+Atherosclerosis+in+Mice+With+Hypercholesterolemia.">Foamy Monocytes Form Early and Contribute to Nascent Atherosclerosis in Mice With Hypercholesterolemia.</a> Arterioscler Thromb Vasc Biol. 35 (8), 1787-1797 (2015).</li><li>Jackson, W. D., Weinrich, T. W., Woollard, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Very-low+and+low-density+lipoproteins+induce+neutral+lipid+accumulation+and+impair+migration+in+monocyte+subsets.">Very-low and low-density lipoproteins induce neutral lipid accumulation and impair migration in monocyte subsets.</a> Scientific Reports. 6, 20038 (2016).</li><li>Angelovich, T. A., Hearps, A. C., Jaworowski, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammation-induced+foam+cell+formation+in+chronic+inflammatory+disease.">Inflammation-induced foam cell formation in chronic inflammatory disease.</a> Immunol. Cell. Biol. 93 (8), 683-693 (2015).</li><li>Llodr&#225;, J., 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=Emigration+of+monocyte-derived+cells+from+atherosclerotic+lesions+characterizes+regressive,+but+not+progressive,+plaques.">Emigration of monocyte-derived cells from atherosclerotic lesions characterizes regressive, but not progressive, plaques.</a> Proc. Natl. Acad. Sci. 101 (32), 11779-11784 (2004).</li><li>Getz, G. S., Reardon, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+Models+of+Atherosclerosis.">Animal Models of Atherosclerosis.</a> Arterioscler. Thromb. Vasc. Biol. 32 (5), 1104-1115 (2012).</li><li>Meir, K. S., Leitersdorf, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atherosclerosis+in+the+Apolipoprotein+E-Deficient+Mouse.+A+Decade+of+Progress.">Atherosclerosis in the Apolipoprotein E-Deficient Mouse. A Decade of Progress.</a> Arterioscler. Thromb. Vasc. Biol. 24 (6), 1006-1014 (2004).</li><li>Hilgendorf, I., Swirski, F. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Making+a+difference:+Monocyte+Heterogeneity+in+Cardiovascular+Disease.">Making a difference: Monocyte Heterogeneity in Cardiovascular Disease.</a> Curr. Atheroscler. Rep. 14 (5), 450-459 (2012).</li><li>Rogacev, K. S., 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=Lower+Apo+A-I+and+Lower+HDL-C+Levels+Are+Associated+With+Higher+Intermediate+CD14++CD16++Monocyte+Counts+That+Predict+Cardiovascular+Events+in+Chronic+Kidney+Disease.">Lower Apo A-I and Lower HDL-C Levels Are Associated With Higher Intermediate CD14++CD16+ Monocyte Counts That Predict Cardiovascular Events in Chronic Kidney Disease.</a> Arterioscler. Thromb. Vasc. Biol. 34 (9), 2120-2127 (2014).</li><li>Rogacev, K. S., 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=CD14++CD16++Monocytes+Independently+Predict+Cardiovascular+Events:+A+Cohort+Study+of+951+Patients+Referred+for+Elective+Coronary+Angiography.">CD14++CD16+ Monocytes Independently Predict Cardiovascular Events: A Cohort Study of 951 Patients Referred for Elective Coronary Angiography.</a> J. Am. Coll. Cardiol. 60 (16), 1512-1520 (2012).</li><li>Justus, C. R., Leffler, N., Ruiz-Echevarria, M., Yang, L. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+Cell+Migration+and+Invasion+Assays.">In vitro Cell Migration and Invasion Assays.</a> J. Vis. Exp. (88), e51046 (2014).</li><li>Boyden, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Chemotactic+Effect+Of+Mixtures+Of+Antibody+And+Antigen+On+Polymorphonuclear+Leucocytes.">The Chemotactic Effect Of Mixtures Of Antibody And Antigen On Polymorphonuclear Leucocytes.</a> J. Exp. Med. 115 (3), 453-466 (1962).</li><li>Westhorpe, C. L. V., 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=Endothelial+cell+activation+promotes+foam+cell+formation+by+monocytes+following+transendothelial+migration+in+an+in+vitro+model.">Endothelial cell activation promotes foam cell formation by monocytes following transendothelial migration in an in vitro model.</a> Exp. Mol. Pathol. 93, 220-226 (2012).</li><li>Quinn, M. T., Parthasarathy, S., Fong, L. G., Steinberg, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidatively+modified+low+density+lipoproteins:+a+potential+role+in+recruitment+and+retention+of+monocyte/macrophages+during+atherogenesis.">Oxidatively modified low density lipoproteins: a potential role in recruitment and retention of monocyte/macrophages during atherogenesis.</a> Proc. Natl. Acad. Sci. 84 (9), 2995-2998 (1987).</li><li>Henriksen, T., Mahoney, E. M., Steinberg, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+macrophage+degradation+of+biologically+modified+low+density+lipoprotein.">Enhanced macrophage degradation of biologically modified low density lipoprotein.</a> Arterioscler. Thromb. Vasc. Biol. 3 (2), 149-159 (1983).</li><li>Parthasarathy, S., Raghavamenon, A., Garelnabi, M. O., Santanam, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Oxidized+Low-Density+Lipoprotein.">Oxidized Low-Density Lipoprotein.</a> Methods Mol. Biol. 610, 403-417 (2010).</li><li>Muller, W. A., Weigl, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monocyte-selective+transendothelial+migration:+dissection+of+the+binding+and+transmigration+phases+by+an+in+vitro+assay.">Monocyte-selective transendothelial migration: dissection of the binding and transmigration phases by an in vitro assay.</a> J. Exp. Med. 176 (3), 819-828 (1992).</li><li>Maisa, A., 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=Monocytes+from+HIV-infected+individuals+show+impaired+cholesterol+efflux+and+increased+foam+cell+formation+after+transendothelial+migration.">Monocytes from HIV-infected individuals show impaired cholesterol efflux and increased foam cell formation after transendothelial migration.</a> AIDS. 29 (12), 1445-1457 (2015).</li><li>Angelovich, T. A., 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=Ex+vivo+foam+cell+formation+is+enhanced+in+monocytes+from+older+individuals+by+both+extrinsic+and+intrinsic+mechanisms.">Ex vivo foam cell formation is enhanced in monocytes from older individuals by both extrinsic and intrinsic mechanisms.</a> Exp. Gerontol. 80, 17-26 (2016).</li><li>Westhorpe, C. L. V., 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=Effects+of+HIV-1+infection+in+vitro+on+transendothelial+migration+by+monocytes+and+monocyte-derived+macrophages.">Effects of HIV-1 infection in vitro on transendothelial migration by monocytes and monocyte-derived macrophages.</a> J. Leukoc. Biol. 85 (6), 1027-1035 (2009).</li><li>Furie, M. B., Cramer, E. B., Naprstek, B. L., Silverstein, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cultured+endothelial+cell+monolayers+that+restrict+the+transendothelial+passage+of+macromolecules+and+electrical+current.">Cultured endothelial cell monolayers that restrict the transendothelial passage of macromolecules and electrical current.</a> J. Cell Biol. 98 (3), 1033-1041 (1984).</li><li>M&#252;ller, A. 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=Expression+of+the+Endothelial+Markers+PECAM-1,+vWf,+and+CD34+in+Vivo+and+in+Vitro.">Expression of the Endothelial Markers PECAM-1, vWf, and CD34 in Vivo and in Vitro.</a> Exp. Mol. Pathol. 72 (3), 221-229 (2002).</li><li>Kelesidis, T., 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=Predictors+of+impaired+HDL+function+in+HIV-1+infected+compared+to+uninfected+individuals.">Predictors of impaired HDL function in HIV-1 infected compared to uninfected individuals.</a> J. Acquir. Immune Defic. Syndr. , (2017).</li><li>Rogacev, K. S., 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=Monocyte+heterogeneity+in+obesity+and+subclinical+atherosclerosis.">Monocyte heterogeneity in obesity and subclinical atherosclerosis.</a> European Heart Journal. 31 (3), 369-376 (2010).</li><li>Gacka, 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=Proinflammatory+and+atherogenic+activity+of+monocytes+in+Type+2+diabetes.">Proinflammatory and atherogenic activity of monocytes in Type 2 diabetes.</a> J. Diabetes Complications. 24 (1), 1-8 (2010).</li><li>Rogacev, K. 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The protocol described here offers a versatile and physiologically relevant method for assessing the atherogenicity of monocytes from human clinical cohorts, by combining both monocyte transmigration and foam cell formation. This model offers advantages over alternative methods of foam cell formation as it takes into account the effect of monocyte transmigration on foam cell formation and allows the measurement of reverse transmigration6 in addition to the inherent propensity of monocytes to matur...

Monocyte transmigration is a crucial step in the development of atherosclerotic plaque that may lead to thrombosis, stroke and myocardial infarction. Atherosclerotic plaques develop from fatty streaks, generally present at sites of low oscillatory blood flow in medium to large arteries, where deposited lipid contributes to endothelial activation and localized inflammation1. Monocytes are recruited to endothelial cells in fatty streaks via monocyte chemotactic proteins (such as CCL2) and transmigrate into the intima2. Following transmigration, monocytes may form atherogenic, lipid-laden macrophages called foam cells as a consequence of lipid uptake, lipid synthesis, down-regulation of cholesterol efflux or a combination of the above factors. Monocytes may also accumulate lipids in the circulation and have a &#39;foamy&#39; phenotype, possibly predisposing cells for foam cell formation3,4. Foam cells are the defining feature of fatty streaks and early-stage atherosclerotic plaques and their formation is influenced by both lipid and inflammatory mediators5. Alternatively, monocytes have the ability to reverse transmigrate from the artery into the bloodstream6, thereby removing lipid from the intima and acting to maintain the health of the artery.
Determining the propensity of monocytes to transmigrate across arterial endothelium and form foam cells in the intima, or to reverse transmigrate and carry lipid out of the plaque, is a key requirement for understanding the role of monocyte activation in increasing atherosclerotic risk. Mouse models of CADs such as atherosclerosis are important in elucidating real-time in vivo information on fatty streak/atherosclerotic plaque development. However, these models require a genetic alteration of the natural cholesterol processing abilities of these animals usually coupled with drastic alterations in diet (such as the ApoE-/- Western-type diet model)7,8, thereby, inducing non-physiological accumulation of circulating lipid levels which drive plaque development. These models may have limited relevance to chronic inflammatory human conditions such as HIV infection which are not associated with increased circulating cholesterol or low-density lipoprotein (LDL) levels. Furthermore, differences in monocyte biology between humans and mice make the testing of immunological questions regarding the relevance of subpopulations of monocytes (such as intermediate monocytes (CD14++CD16+))9 difficult. This is important when studying the mechanisms driving cardiovascular disease as intermediate monocyte counts independently predict cardiovascular events10,11. While assays exist to sequentially measure either monocyte transmigration or foam cell formation in isolation, no in vitro assay has been validated for quantifying both aspects of early atherogenesis using the same cells from clinical cohorts. Transwell models utilize a modified Boyden two-chamber system whereby cells are loaded into the top chamber and transmigrate across a porous plastic barrier or cell monolayer into a lower chamber that typically contains media with chemoattractant12,13. Whilst widely used for analyzing leukocyte transmigration, these models do not generally incorporate a layer representing the intima, resulting in transmigrated cells migrating into solution, and do not allow for the measurement of foam cell formation or reverse transmigration of the same cells. Conversely, models of foam cell formation do not account for any transmigratory-induced changes to monocytes or effects of endothelial activation which is known to contribute to foam cell formation14. Furthermore, these systems induce foam cell formation from macrophages adhered to cell culture plates by the addition of saturating concentrations of exogenous oxidized low-density lipoprotein (oxLDL)15,16, a key inducer of foam cell formation. LDL used in these models is often oxidized by non-physiologically-relevant processes such as CuSO4 treatment17, therefore, questioning the physiological importance of studies using these models.
Here we describe an assay that quantifies monocyte transmigration and foam cell formation of the same cells which does not require the addition of exogenous oxLDL, thus better modelling the role of monocytes in foam cell formation. This model was originally developed by Professor William Muller (Northwestern University, Chicago)18, and has been further refined in our laboratory to assess ex vivo the atherogenicity of monocytes isolated under non-activating conditions from individuals with underlying inflammatory conditions accompanying diseases such as HIV infection19 as well as ageing20, that are associated with an increased risk of atherosclerosis. This model also provides a platform for answering basic biological questions regarding the propensity of different monocyte subsets to form foam cells20, the influence of endothelial activation by cytokines such as TNF on foam cell formation14, and the migratory properties of monocytes such as the depth and speed of transmigration in gels19. Furthermore, monocyte transmigration and foam cell formation can be quantified using standard microscopy, live cell imaging, flow cytometry and imaging flow cytometry, therefore, providing a versatile method to evaluate the role of monocytes in atherogenesis.

<table border="0" cellpadding="0" cellspacing="0" width="1187">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Gel preparation reagents</td>
			<td style="width:128px;"></td>
			<td style="width:111px;"></td>
			<td style="width:595px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">NaOH</td>
			<td>Sigma-Aldrich</td>
			<td>221465-500G</td>
			<td>0.1 M NaOH diluted in H20</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">10X M199</td>
			<td>Sigma-Aldrich</td>
			<td style="width:111px;">M0650</td>
			<td style="width:595px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">AcCOOH</td>
			<td>Sigma-Aldrich</td>
			<td>695092-100ML</td>
			<td>20 mM Acetic acid diluted in H20</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cultrex Bovine Collagen I</td>
			<td>R&#38;D Systems</td>
			<td>3442-050-01</td>
			<td>Type I Fibrous Collagen</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Name</td>
			<td style="width:128px;">Company</td>
			<td style="width:111px;">Catalog Number</td>
			<td style="width:595px;">Comments</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cell culture</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">M199</td>
			<td>Life Technologies</td>
			<td>11150-059</td>
			<td style="width:595px;">M199 media containing Earle&#39;s salts, L-glutamine and 2.2 g/L Sodium Bicarbonate. 
			Media supplemented with 100 &#181;g/mL L-glutamine&#160; and 100 U/mL penicillin/streptomycin&#160;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">M20</td>
			<td></td>
			<td></td>
			<td style="width:595px;">Supplemented M199 containing 20% heat-inactivated pooled or donor serum. 
			Individual lipid species such as LDL can be added to M199.</td>
		</tr>
		<tr height="60">
			<td height="60" style="height:60px;">HUVEC</td>
			<td></td>
			<td></td>
			<td style="width:595px;">Primary human umbilical cord endothelial cells (HUVEC) can be isolated from umbilical cords donated with informed consent and ethics approval. Isolated HUVEC may also be purchased commercially.</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Human coronary artery endothelial cells</td>
			<td></td>
			<td></td>
			<td style="width:595px;">Primary human coronary artery endothelial cells can be isolated from arteries donated with informed consent and ethics approval. Isolated cells may also be purchased commercially.</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">EDTA</td>
			<td>BDH Merck</td>
			<td>10093.5V</td>
			<td>Ethylenediaminetetraacetic acid (EDTA) - 0.5 M, pH 8.0</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">EGTA</td>
			<td>Sigma-Aldrich</td>
			<td>E3889-500G</td>
			<td>Ethylene glycol-bis(&#946;-aminoethyl ether)-N,N,N&#39;,N&#39;-tetraacetic acid (EGTA) - 1 mM, pH 8.0</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">0.05% trypsin EDTA</td>
			<td>Gibco</td>
			<td>25300-054</td>
			<td>0.05% trypsin/0.53 EDTA (1X)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">L-glutamine</td>
			<td>Gibco</td>
			<td>25030-081</td>
			<td>L-glutamine (200 mM)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Penicillin/streptomycin&#160;</td>
			<td>Gibco</td>
			<td>15140-122</td>
			<td>Penicillin/streptomycin (10,000 units/mL Penicillin and 10,000 &#181;g/mL Streptomycin)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">New born calf serum</td>
			<td style="width:128px;">Gibco</td>
			<td style="width:111px;">16010-142</td>
			<td style="width:595px;">New born calf serum: New Zealand origin</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Fibronectin</td>
			<td>Sigma-Aldrich</td>
			<td>F1056-1MG</td>
			<td>Fibronectin - 50 &#181;g/mL aliquots prepared and stored</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">PBS (1X)</td>
			<td>Gibco</td>
			<td>14200-075</td>
			<td>Dulbecco&#39;s Phosphate Buffered Saline (10X): Dilute to 1X with sterile H20</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">0.1% TNF</td>
			<td>Gibco</td>
			<td>PHC3015</td>
			<td>Recombinant human TNF - Reconstituted in H20 and stored in 10 &#181;g/mL aliquots</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Low-density lipoprotein</td>
			<td>Merck Millipore</td>
			<td>LP2-2MG</td>
			<td>Low-density lipoprotein (LDL)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Name</td>
			<td style="width:128px;">Company</td>
			<td style="width:111px;">Catalog Number</td>
			<td style="width:595px;">Comments</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Microscopy</td>
			<td style="width:128px;"></td>
			<td style="width:111px;"></td>
			<td style="width:595px;"></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">1 or 2% formaldehyde</td>
			<td>Polysciences</td>
			<td>4018</td>
			<td>1 or 2% formaldehyde diluted with sterile H20</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">50% and 78% methanol</td>
			<td>Ajax Finechem</td>
			<td>318-2.5L GL</td>
			<td>50% or 78% v/v methanol, diluted with H20</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Oil Red O stain</td>
			<td>Sigma-Aldrich</td>
			<td>O0625-25G</td>
			<td>Dilute to 2 mg/mL in 22% 1M NaOH and 78% (v/v) methanol</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microscope slides</td>
			<td>Mikro-Glass</td>
			<td>S41104AMK</td>
			<td style="width:595px;">Twin frosted 45 degree ground edge microscope slides (25 X 76 mm)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cover slips</td>
			<td>Menzel-Gl&#228;ser</td>
			<td>MENCS224015GP</td>
			<td>22 x 40 mm #1.5 size glass cover slips</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Double-sided tape</td>
			<td>3M Scotch</td>
			<td>4011</td>
			<td>Super strength exterior mounting tape (25.4 mm x 1.51 m)</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">Giemsa stain</td>
			<td>Merck Millipore</td>
			<td>1.09204.0500</td>
			<td>Giemsa&#39;s azur eosin methylene blue solution (dilute stock 1:10 in H20)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Hole punch</td>
			<td style="width:128px;"></td>
			<td style="width:111px;"></td>
			<td style="width:595px;">Hand-held single hole punch (6.35 mm punch)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Name</td>
			<td style="width:128px;">Company</td>
			<td style="width:111px;">Catalog Number</td>
			<td style="width:595px;">Comments</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Flow cytometry</td>
			<td style="width:128px;"></td>
			<td style="width:111px;"></td>
			<td style="width:595px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Collagenase D</td>
			<td>Roche Diagnostics</td>
			<td>11088858001</td>
			<td>Collagenase D diluted in M199 media to 1 mg/mL&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">35 &#181;m nylon mesh capped polystyrene FACS tubes</td>
			<td>BD Biosciences</td>
			<td>352235</td>
			<td>35 &#181;m nylon mesh capped polystyrene FACS tubes</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Live/Dead Fixable Yellow Dead Cell stain</td>
			<td>Life Technologies</td>
			<td>L34959</td>
			<td>Live/Dead Fixable Yellow Dead Cell stain</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">FACS wash</td>
			<td></td>
			<td></td>
			<td>Prepare by mixing 1 X PBS-, 2 mM EDTA and 1% New born calf serum</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Name</td>
			<td style="width:128px;">Company</td>
			<td style="width:111px;">Catalog Number</td>
			<td style="width:595px;">Comments</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;width:355px;">Plasticware</td>
			<td style="width:128px;"></td>
			<td style="width:111px;"></td>
			<td style="width:595px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">96 well plate</td>
			<td>Nunclon</td>
			<td>167008</td>
			<td>Delta surface flat-bottomed 96 well plate</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">10 cm Petri Dish</td>
			<td>TPP</td>
			<td>93100</td>
			<td>Sterile 10 cm Petri dish</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1.5 mL Eppendorf tubes</td>
			<td>Eppendorf</td>
			<td>0030 125.150</td>
			<td>Eppendorf tubes</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Transfer pipette</td>
			<td>Samco Scientific</td>
			<td>222-20S</td>
			<td>Sterile transfer pipette (1 mL, large bulb)</td>
		</tr>
	</tbody>
</table>

quantification of monocyte transmigration and foam cell formation from individuals with chronic inflammatory conditions

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Atherosclerosis, a leading cause of CAD, is initiated by the transmigration of innate immune monocytes to inflammatory sites of deposited lipid called fatty streaks, which are present in arterial walls of medium to large arteries. The key pathogenic feature of lesions at this early stage of atherosclerosis is the maturation of monocytes which migrate into arteries to form foam cells or lipid-laden macrophages. Considerable evidence supports the hypothesis that risk of atherosclerosis is increased by chronic inflammatory conditions accompanying diseases such as rheumatoid arthritis and HIV, as well as general ageing, and that this risk is predicted by monocyte activation. While mouse models provide a good platform to investigate the role of monocytes in atherogenesis in vivo, they require genetic alteration of natural cholesterol metabolism and drastic alteration of normal mouse diets, and have limited suitability for the study of atherogenic influences of human comorbid diseases. This motivated us to develop a human in vitro model to measure the atherogenic potential of monocytes isolated from individuals with defined disease states. Currently, human in vitro models are limiting in that they evaluate monocyte transmigration and foam cell formation in isolation. Here we describe a protocol in which monocytes isolated from patient blood transmigrate across human endothelial cells into a type 1 collagen matrix, and their propensity to mature into foam cells in the presence or absence of exogenous lipid is measured. The protocol has been validated for the use of human monocytes purified from individuals with HIV infection and elderly HIV uninfected individuals. This model is versatile and allows monocyte transmigration and foam cell formation to be evaluated using either microscopy or flow cytometry as well as allowing the assessment of atherogenic factors present in serum or plasma.

Quantifying monocyte transmigration
Monocytes are added to the model as described in Figure 1, and six gels are prepared for each condition. Monocytes for 6 gels per donor (i.e., 5.0 x 104 monocytes per gel 6 gels = 3.0 x 105 monocytes per donor) are resuspended to a final volume of 600 &#181;L of M199 media containing the required serum/isolated lipid...

Watch this Scientific Journal Video about Quantification of Monocyte Transmigration and Foam Cell Formation from Individuals with Chronic Inflammatory Conditions at JoVE.com

Quantification of Monocyte Transmigration and Foam Cell Formation from Individuals with Chronic Inflammatory Conditions

We describe a protocol to measure transmigration by monocytes across human endothelial monolayers and their subsequent maturation into foam cells. This provides a versatile method to assess the atherogenic properties of monocytes isolated from people with different disease conditions and to evaluate factors in blood which may enhance this propensity.

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Atherosclerosis, a leading cause of CAD, is initiated by the ...

The overall goal of this assay is to quantify the capacity for monocytes from human clinical samples to undergo transendothelial migration and foam cell formation. This method can be used to answer key questions in the cardiovascular field such the atherogenic potential of cells from individuals who are at risk of acute coronary artery disease. The major advantage of this technique is that clinical samples can be measured both from fresh whole blood or stored patient cohorts.Furthermore, foam cell formation can be quantified by both microscopy and flow cytometry. First, prepare the polymerized collagen gels from a fresh collagen suspension. To a five-milliliter polystyrene tube, add sodium hydroxide, then 10 times M199, then acidic acid, and finally, add fibrous collagen.Mix this well by pipetting. Next, aliquot 50 microliters into the internal wells of a sterile flat-bottomed 96-well tissue culture plate. In the outer edges of wells, load 200 microliters of one times Dulbecco PBS to prevent desiccation.After two hours of incubation at 37 degrees Celsius, the collagen will polymerize. Then, overlay the gels with 150 microliters of one times supplemented M199 and incubate them until needed for use five days later. To expand stored human umbilical vein endothelial cells, prepare a 25-square-centimeter culture flask with one milliliter of fibronectin solution and incubate the dish for 10 minutes at room temperature.Meanwhile, thaw the stored cells in a water bath to resuspend them in M20. Once the cells are thawed, aspirate any residual fibronectin solution from the dish and plate the cells. Then, culture to confluence by replacing the media after two to three days.The HUVECs should be confluent on day five of culturing. Detach them by aspirating the culture's supernatant from the flask, and then wash away the serum-containing media using two to three milliliters of one times PBS. Then, add five milliliters of diluted trypsin and incubate the cells briefly at room temperature shaking the cells gently until they appear detached.Then, quickly collect them with five-milliliters of M20 and transfer the suspension to a 10-milliliter tube and centrifuged cells. Now, resuspend the cells in M20 at 200, 000 cells per milliliter. Then, aspirate the M199 from the prepared collagen plate and add 100 microliters of HUVECs to each gel.Continue the culture for three days. On day eight of culturing the HUVECs, activate the monolayers prior to adding the monocytes. After aspirating the overlaying media, add 100 microliters of human TNF-alpha solution to each well.Then, incubate the plate at 37 degrees Celsius for four hours. After the incubation, remove the media and wash the gels twice using 100 microliters of M199 per wash. Now, add 50, 000 freshly isolated monocytes or purified monocyte subsets in 100 microliters of M20 to the HUVEC monolayers.After adding the monocytes, incubate the plate for an hour to allow for forward transmigration of the cells. After an hour, collect the non-transmigrated cells in wash solution. Start by pooling two EGTA washes using 100 microliters per well.Then, spin down the combined wash solutions at 300 G for five minutes at four degrees Celsius. Discard the supernatant, and resuspend the cells in 30 microliters of PBS and count the cells to determine the percentage of forward transmigrated cells. Now, wash plate wells once with M199 and add 100 microliters of fresh M20 to the plate wells and incubate the plate for two days.After two days, repeat the procedure for collecting the non-transmigrated cells in EGTA wash solution in order to collect reverse transmigrated cells and proceed with phenotypic analysis of the cells. To phenotypically characterize the gel-bound cells by FACS analysis, digest the cells by adding 100 microliters of 37-degrees-Celsius collagenese D and incubating for 20 minutes at 37 degrees Celsius. Following the incubation, macerate the gels using a 200-microliter pipette tip and incubate them for a further 20 minutes to fully digest the gels.Once fully digested, filter and pool the digested replicate gels through a 35-micron nylon mesh into a FACS tube on ice. Now, wash the filtered cells once with cold FACS wash solution. Centrifuge the cells and resuspend them in 100 microliters of cold wash solution.Then, perform FACS staining and analysis according to the text protocol. To analyze the cells by microscopy, first stain the cells as described in the text protocol. To detach the stained cells, rim the wells using a 21-gauge needle with the bevel facing outwards.Next, prepare slides to mount the gels. Punch two small holes into a strip of double-sided tape and then fix the tape to the slide and remove the protective coating. Next, add a drop of water to each hole in the tape.Then, using tweezers, gently transfer two gels onto the two holes and cover the tape. Finally, carefully attach a coverslip to the tape and proceed with visualization of the cells. Following transmigration, non-transmigrated cells were counted as described.A total of 15, 000 non-transmigrated cells were recovered, and the percentage of forward transmigration was determined to be 95%Following 48 hours of further incubation, 36, 000 reverse transmigrated cells were recovered which amounted to 12.6%reverse transmigration. Staining the gels with oil red O revealed foam cells pointed out by white arrows and macrophages pointed out with black arrows. These monocytes were treated with oxidized LDL during transmigration, a substance used to induce foam cell formation in conventional foam cell induction models.Aggregate cell count data from 12 donors confirmed that the incubation of monocytes with oxidized LDL induced more foam cell formation than when monocytes are incubated with native LDL or M199 media alone. The transmigrated cells were also analyzed by flow cytometry. After excluding dead cells, doublets and CD45 negative HUVECs, the major population of migrated cells was selected and the mean fluorescence intensity of the receptors of interest was compared with the fluorescence minus one or isotype control data.After watching this video, you should have a good understanding of how to use this assay to quantify monocyte transendothelial migration and foam cell formation from human clinical samples. Don't forget that working with human clinical samples can be extremely hazardous and good laboratory technique must always be used.

quantification-monocyte-transmigration-foam-cell-formation-from

Research

JoVE Journal

Immunology and Infection

Isolation of Human Umbilical Vein Endothelial Cells and Their Use in the Study of Neutrophil Transmigration Under Flow Conditions

Neutrophils are the most abundant type of white blood cell. They form an essential part of the innate immune system1. During acute inflammation, neutrophils are the first inflammatory cells to migrate to the site of injury. Recruitment of neutrophils to an injury site is a stepwise process that includes first, dilation of blood vessels to increase blood flow; second, microvascular structural changes and escape of plasma proteins from the bloodstream; third, rolling, adhesion and transmigration of the neutrophil across the endothelium; and fourth accumulation of neutrophils at the site of injury2,3. A wide array of in vivo and in vitro methods has evolved to enable the study of these processes4. This method focuses on neutrophil transmigration across human endothelial cells.
One popular method for examining the molecular processes involved in neutrophil transmigration utilizes human neutrophils interacting with primary human umbilical vein endothelial cells (HUVEC)5. Neutrophil isolation has been described visually elsewhere6; thus this article will show the method for isolation of HUVEC. Once isolated and grown to confluence, endothelial cells are activated resulting in the upregulation of adhesion and activation molecules. For example, activation of endothelial cells with cytokines like TNF-&alpha; results in increased E-selectin and IL-8 expression7. E-selectin mediates capture and rolling of neutrophils and IL-8 mediates activation and firm adhesion of neutrophils. After adhesion neutrophils transmigrate. Transmigration can occur paracellularly (through endothelial cell junctions) or transcellularly (through the endothelial cell itself). In most cases, these interactions occur under flow conditions found in the vasculature7,8.
The parallel plate flow chamber is a widely used system that mimics the hydrodynamic shear stresses found in vivo and enables the study of neutrophil recruitment under flow condition in vitro9,10. Several companies produce parallel plate flow chambers and each have advantages and disadvantages. If fluorescent imaging is needed, glass or an optically similar polymer needs to be used. Endothelial cells do not grow well on glass.
Here we present an easy and rapid method for phase-contrast, DIC and fluorescent imaging of neutrophil transmigration using a low volume ibidi channel slide made of a polymer that supports the rapid adhesion and growth of human endothelial cells and has optical qualities that are comparable to glass. In this method, endothelial cells were grown and stimulated in an ibidi &mu;slide. Neutrophils were introduced under flow conditions and transmigration was assessed. Fluorescent imaging of the junctions enabled real-time determination of the extent of paracellular versus transcellular transmigration.

This article first describes a procedure for isolating human endothelial cells from umbilical veins and then shows how to use these cells to examine neutrophil transmigration under flow conditions. By using a low-volume flow chamber made from a polymer with the optical characteristics of glass, live-cell fluorescent imaging of rare cell populations is also possible.

Neutrophils are the most abundant type of white blood cell. They form an essential part of the innate immune system1. During acute inflammation, ...

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae

Nasopharyngeal colonization by Streptococcus pneumoniae is a prerequisite to invasion to the lungs or bloodstream1. This organism is capable of colonizing the mucosal surface of the nasopharynx, where it can reside, multiply and eventually overcome host defences to invade to other tissues of the host. Establishment of an infection in the normally lower respiratory tract results in pneumonia. Alternatively, the bacteria can disseminate into the bloodstream causing bacteraemia, which is associated with high mortality rates2, or else lead directly to the development of pneumococcal meningitis. Understanding the kinetics of, and immune responses to, nasopharyngeal colonization is an important aspect of S. pneumoniae infection models.
Our mouse model of intranasal colonization is adapted from human models3 and has been used by multiple research groups in the study of host-pathogen responses in the nasopharynx4-7. In the first part of the model, we use a clinical isolate of S. pneumoniae to establish a self-limiting bacterial colonization that is similar to carriage events in human adults. The procedure detailed herein involves preparation of a bacterial inoculum, followed by the establishment of a colonization event through delivery of the inoculum via an intranasal route of administration. Resident macrophages are the predominant cell type in the nasopharynx during the steady state. Typically, there are few lymphocytes present in uninfected mice8, however mucosal colonization will lead to low- to high-grade inflammation (depending on the virulence of the bacterial species and strain) that will result in an immune response and the subsequent recruitment of host immune cells. These cells can be isolated by a lavage of the tracheal contents through the nares, and correlated to the density of colonization bacteria to better understand the kinetics of the infection.

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae

Colonization of the murine nasopharynx with Streptococcus pneumoniae and the subsequent extraction of adherent or recruited cells is described. This technique involves flushing the nasopharynx and collection of the fluid through the nares and is adaptable for various readouts, including differential cell quantification and analysis of mRNA expression in situ.

Nasopharyngeal colonization by Streptococcus pneumoniae is a prerequisite to invasion to the lungs or bloodstream1. This organism is capable of colonizing ...

Real-time Imaging of Endothelial Cell-cell Junctions During Neutrophil Transmigration Under Physiological Flow

During inflammation, leukocytes leave the circulation and cross the endothelium to fight invading pathogens in underlying tissues. This process is known as leukocyte transendothelial migration. Two routes for leukocytes to cross the endothelial monolayer have been described: the paracellular route, i.e., through the cell-cell junctions and the transcellular route, i.e., through the endothelial cell body. However, it has been technically difficult to discriminate between the para- and transcellular route. We developed a simple in vitro assay to study the distribution of endogenous VE-cadherin and PECAM-1 during neutrophil transendothelial migration under physiological flow conditions. Prior to neutrophil perfusion, endothelial cells were briefly treated with fluorescently-labeled antibodies against VE-cadherin and PECAM-1. These antibodies did not interfere with the function of both proteins, as was determined by electrical cell-substrate impedance sensing and FRAP measurements. Using this assay, we were able to follow the distribution of endogenous VE-cadherin and PECAM-1 during transendothelial migration under flow conditions and discriminate between the para- and transcellular migration routes of the leukocytes across the endothelium.

Leukocytes cross the endothelial monolayer using the paracellular or the transcellular route. We developed a simple assay to follow the distribution of endogenous junctional VE-cadherin and PECAM-1 during leukocyte transendothelial migration under physiological flow to discriminate between the two transmigration routes.

During inflammation, leukocytes leave the circulation and cross the endothelium to fight invading pathogens in underlying tissues. This process is known ...

Isolation of Exosomes from the Plasma of HIV-1 Positive Individuals

Exosomes are small vesicles ranging in size from 30 nm to 100 nm that are released both constitutively and upon stimulation from a variety of cell types. They are found in a number of biological fluids and are known to carry a variety of proteins, lipids, and nucleic acid molecules. Originally thought to be little more than reservoirs for cellular debris, the roles of exosomes regulating biological processes and in diseases are increasingly appreciated.
Several methods have been described for isolating exosomes from cellular culture media and biological fluids. Due to their small size and low density, differential ultracentrifugation and/or ultrafiltration are the most commonly used techniques for exosome isolation. However, plasma of HIV-1 infected individuals contains both exosomes and HIV viral particles, which are similar in size and density. Thus, efficient separation of exosomes from HIV viral particles in human plasma has been a challenge.
To address this limitation, we developed a procedure modified from Cantin et. al., 2008 for purification of exosomes from HIV particles in human plasma. Iodixanol velocity gradients were used to separate exosomes from HIV-1 particles in the plasma of HIV-1 positive individuals. Virus particles were identified by p24 ELISA. Exosomes were identified on the basis of exosome markers acetylcholinesterase (AChE), and the CD9, CD63, and CD45 antigens. Our gradient procedure yielded exosome preparations free of virus particles. The efficient purification of exosomes from human plasma enabled us to examine the content of plasma-derived exosomes and to investigate their immune modulatory potential and other biological functions.

Techniques describing a gradient procedure to separate exosomes from human immunodeficiency virus (HIV) particles are described. This procedure was used to isolate exosomes away from HIV particles in human plasma from HIV-infected individuals. The isolated exosomes were analyzed for cytokine/chemokine content.

Exosomes are small vesicles ranging in size from 30 nm to 100 nm that are released both constitutively and upon stimulation from a variety of cell types. ...

Induction of an Inflammatory Response in Primary Hepatocyte Cultures from Mice

The liver plays a decisive role in the regulation of systemic inflammation. In chronic kidney disease in particular, the liver reacts in response to the uremic milieu, oxidative stress, endotoxemia and the decreased clearance of circulating proinflammatory cytokines by producing a large number of acute-phase reactants. Experimental tools to study inflammation and the underlying role of hepatocytes are crucial to understand the regulation and contribution of hepatic cytokines to a systemic acute phase response and a prolonged pro-inflammatory scenario, especially in an intricate setting such as chronic kidney disease. Since studying complex mechanisms of inflammation in vivo remains challenging, resource-intensive and usually requires the usage of transgenic animals, primary isolated hepatocytes provide a robust tool to gain mechanistic insights into the hepatic acute-phase response. Since this in vitro technique features moderate costs, high reproducibility and common technical knowledge, primary isolated hepatocytes can also be easily used as a screening approach. Here, we describe an enzymatic-based method to isolate primary murine hepatocytes, and we describe the assessment of an inflammatory response in these cells using ELISA and quantitative real-time PCR.

Here, we show an enzymatic approach to isolate primary hepatocytes from adult mice, and we describe the quantification of an inflammatory response using ELISA and real-time PCR.

The liver plays a decisive role in the regulation of systemic inflammation. In chronic kidney disease in particular, the liver reacts in response to the ...

Quantification of Monocyte Chemotactic Activity In Vivo and Characterization of Blood Monocyte Derived Macrophages

Tissue homeostasis and repair are critically dependent on the recruitment of monocyte-derived macrophages. Both under- and over-recruitment of monocyte-derived macrophages can impair wound healing. We showed that high fat and high sugar diets promote monocyte priming and dysfunction, converting healthy blood monocytes into a hyper chemotactic phenotype poised to differentiate into macrophages with dysregulated activation profiles and impaired phenotypic plasticity. The over-recruitment of monocyte-derived macrophages and recruitment of macrophages with dysregulated activation profiles is believed to be a major contributor to the development of chronic inflammatory diseases associated with metabolic disorders, including atherosclerosis and obesity. The goal of this protocol is to quantify the chemotactic activity of blood monocytes as a biomarker for monocyte priming and dysfunction and to characterize the macrophage phenotype blood monocytes are poised to differentiate into in these mouse models. Using single cell Western blot analysis, we show that after 24 h 33%of cells recruited into MCP-1-loaded basement membrane-derived gel plugs injected into mice are monocytes and macrophages; 58% after day 3. However, on day 5, monocyte and macrophage numbers were significantly decreased. Finally, we show that this assays also allows for the isolation of live macrophages from the surgically retrieved basement membrane-derived gel plugs, which can then be subjected to subsequent characterization by single cell Western blot analysis.

Here we present a protocol to quantify the chemotactic activity of blood monocytes in mouse models, to assess the effects of nutritional, pharmacological and genetic interventions on blood monocyte and to characterize the blood monocytes derived macrophages in mouse models using monocyte-chemoattractant protein-1 (MCP-1)-loaded basement membrane-derived gel plugs.

Tissue homeostasis and repair are critically dependent on the recruitment of monocyte-derived macrophages. Both under- and over-recruitment of ...

Separation of Rat Epidermis and Dermis with Thermolysin to Detect Site-Specific Inflammatory mRNA and Protein

Easy-to-use and inexpensive techniques are needed to determine the site-specific production of inflammatory mediators and neurotrophins during skin injury, inflammation, and/or sensitization. The goal of this study is to describe an epidermal-dermal separation protocol using thermolysin, a proteinase that is active at 4 &deg;C. To illustrate this procedure, Sprague Dawley rats are anesthetized, and right hind paws are injected with carrageenan. Six and twelve hours after injection, rats with inflammation and na&iuml;ve rats are euthanized, and a piece of hind paw, glabrous skin is placed in cold Dulbecco's Modified Eagle Medium. The epidermis is then separated at the basement membrane from the dermis by thermolysin in PBS with calcium chloride. Next, the dermis is secured by microdissection forceps, and the epidermis is gently teased away. Toluidine blue staining of tissue sections show that the epidermis is separated cleanly from the dermis at the basement membrane. All keratinocyte cell layers remain intact, and the epidermal rete ridges along with indentations from dermal papillae are clearly observed. Qualitative and real-time RT-PCR is used to determine nerve growth factor and interleukin-6 expression levels. Western blotting and immunohistochemistry are finally performed to detect amounts of nerve growth factor. This report illustrates that cold thermolysin digestion is an effective method to separate epidermis from dermis for evaluation of mRNA and protein alterations during inflammation.

Presented here is a protocol for the separation of epidermis from dermis to evaluate inflammatory mediator production. Following inflammation, rat hind paw epidermis is separated from the dermis by thermolysin at 4 &#176;C. The epidermis is then used for mRNA analysis by RT-PCR and protein evaluation by western blot and immunohistochemistry.

Easy-to-use and inexpensive techniques are needed to determine the site-specific production of inflammatory mediators and neurotrophins during skin ...

Isolation of Adipogenic and Fibro-Inflammatory Stromal Cell Subpopulations from Murine Intra-Abdominal Adipose Depots

The stromal-vascular fraction (SVF) of white adipose tissue (WAT) is remarkably heterogeneous and consists of numerous cell types that contribute functionally to the expansion and remodeling of WAT in adulthood. A tremendous barrier to studying the implications of this cellular heterogeneity is the inability to readily isolate functionally distinct cell subpopulations from WAT SVF for in vitro and in vivo analyses. Single-cell sequencing technology has recently identified functionally distinct fibro-inflammatory and adipogenic PDGFR&#946;+ perivascular cell subpopulations in intra-abdominal WAT depots of adult mice. Fibro-inflammatory progenitors (termed, &#8220;FIPs&#8221;) are non-adipogenic collagen producing cells that can exert a pro-inflammatory phenotype. PDGFR&#946;+ adipocyte precursor cells (APCs) are highly adipogenic both in vitro and in vivo upon cell transplantation. Here, we describe multiple methods for the isolation of these stromal cell subpopulations from murine intra-abdominal WAT depots. FIPs and APCs can be isolated by fluorescence-activated cell sorting (FACS) or by taking advantage of biotinylated antibody-based immunomagnetic bead technology. Isolated cells can be used for molecular and functional analysis. Studying the functional properties of stromal cell subpopulation in isolation will expand our current knowledge of adipose tissue remodeling under physiological or pathological conditions on the cellular level.

This protocol describes the technical approach to isolate adipogenic and fibro-inflammatory stromal cell subpopulations from murine intra-abdominal white adipose tissue (WAT) depots by fluorescence-activated cell sorting or immunomagnetic bead separation.

The stromal-vascular fraction (SVF) of white adipose tissue (WAT) is remarkably heterogeneous and consists of numerous cell types that contribute ...

Real-Time Quantification of Reactive Oxygen Species in Neutrophils Infected with Meningitic Escherichia Coli

Escherichia coli (E. coli) is the most common Gram-negative bacteria causing neonatal meningitis. The occurrence of bacteremia and bacterial penetration through the blood-brain barrier are indispensable steps for the development of E. coli meningitis. Reactive oxygen species (ROS) represent the major bactericidal mechanisms of neutrophils to destroy the invaded pathogens. In this protocol, the time-dependent intracellular ROS production in neutrophils infected with meningitic E. coli was quantified using fluorescent ROS probes detected by a real-time fluorescence microplate reader. This method may also be applied to the assessment of ROS production in mammalian cells during pathogen-host interactions.

Real-Time Quantification of Reactive Oxygen Species in Neutrophils Infected with Meningitic Escherichia Coli

Escherichia coli is the leading cause of neonatal Gram-negative bacterial meningitis. During the bacterial infection, reactive oxygen species produced by neutrophils play a major bactericidal role. Here we introduce a method to detect the reactive oxygen species in neutrophils in response to meningitis E. coli.

Escherichia coli (E. coli) is the most common Gram-negative bacteria causing neonatal meningitis. The occurrence of bacteremia and bacterial penetration ...

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.

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 ...