We thank Paula Cobos and Dr. Evros Vassiliou for lab assistance and providing the mouse macrophages, respectively. We also thank our lab manager Richard Criasia for guidance and help with materials. Finally, the authors thank Ramanpreet Kaur for help with video production.

1. Tissue Culture
<ol>
 <li>Use Mus musculus macrophages (BALB/c mice) for cholera toxin determinations. Initially culture all of M. musculus cells following vendor's instructions.</li>
 <li>Propagate BALB/c mice cells in Dulbecco's Modified Eagle's Medium with L-glutamine completed with 10% fetal bovine serum, and 1% antibiotic/antimycotic or RPMI 1640 base media completed with 10% fetal bovine serum, 5% L-glutamine, and 1% antibiotic/antimycotic reagent.</li>
 <li>Grow cells in 75 cm2 corning flasks with vented caps at 37 &deg;C, 95% air and 5% CO2.</li>
 <li>Bring up human intestinal epithelial cells within 24 hr of delivery as per manufacturer's instructions for the determination of fatty acid determinations.</li>
 <li>Propagate the human intestinal epithelia cells in 75 cm2 corning flasks with vented caps in HybriCare media completed with 10% FBS and 30 ng/ ml human EGF at 37 &deg;C. Do not use Antibiotic/antimycotic reagents as per manufacturer's instructions.</li>
 <li>Split all cells (1:3) at approximately 70% confluency.</li>
 <li>Freeze and bring up all cells throughout the study using standard freezing protocols.</li>
 <li>Note: For larger scale concentration determination of fatty acids, use the faster growing, easier to maintain, mouse macrophages initially. For fine scale fatty acid concentration determination, use human epithelial cells. Use mouse macrophages for all cholera toxin treatments (see discussion).</li>
</ol>
2. Fatty Acid and Cholera Toxin Treatments
<ol>
 <li>Transfer oleic, linoleic and linolenic acids from company-provided glass ampules to sterilized glass vials.</li>
 <li>Transfer each fatty acid to a separate sterilized Eppendorf tube and dissolve it first in 100% ethanol at a dilution of 1:6, and then in RPMI 1640 incomplete media for a final concentration of 10 &mu;g/&mu;l.</li>
 <li>Vortex each solution and transfer it to glass vials for storage in the freezer (-20 &deg;C).</li>
 <li>Plate cells at 2,500 cells/well in 96 well tissue culture plates.</li>
 <li>Add the appropriate complete media to bring the total well volume to 200 &mu;l for treatment of cells with fatty acids in preparation for MTT assays.</li>
 <li>After a 24 hr proliferation period, remove the media and replace it with fresh media.</li>
 <li>Add the appropriate concentrations of each fatty acid to be tested to the wells (see results). Add complete media to bring the total well volumes to 200 &mu;l.</li>
 <li>Incubate the treated plates for 24 hr before beginning the MTT assay.</li>
 <li>Dissolve the cholera toxin in PBS at a concentration of 1 mg/ml and aliquot the solution in cryovials and store the cryovials at 2-8 &deg;C.</li>
 <li>For cell treatments, dilute the toxin 1:100 in either sterilized PBS (pH 7.4) or incomplete DMEM for a final working concentration of 1 ng/&mu;l.</li>
 <li>To treat cells with cholera toxin in preparation for MTT assays, plate cells as described above.</li>
 <li>After a 24 hr proliferation period, add the appropriate concentrations of cholera toxin (for our concentrations, see results) to be tested to the wells following the procedures used in fatty acid applications (above).</li>
 <li>Incubate the treated plates for 24 hr before beginning the MTT assay.</li>
 <li>As a positive (positive c throughout the paper) and negative control (negative c), for both fatty acid and cholera toxin treatments, incubate cells with complete medium and 70% ethanol, respectively.</li>
 <li>For all samples and treatments use a minimum of three replications (n=3), with more replications for positive controls (n=6 in this study).</li>
</ol>
3. MTT Assay
<ol>
 <li>Make a MTT stock solution to a concentration of 2.5 mg/ml.</li>
 <li>Remove the solution in each well of the 96 well plate to be tested and replace it with 200 &mu;l of fresh complete media solution.</li>
 <li>Add 10 &mu;l of the MTT solution to each well.</li>
 <li>Incubate the plate at 37 &deg;C for 3-4 hr.</li>
 <li>Discard the media solution and add 100 &mu;l of 0.04 M HCl in isopropanol to each well.</li>
 <li>Incubate the plate at room temperature for five minutes.</li>
 <li>Transfer the solution from each well to a new centrifuge tube.</li>
 <li>Centrifuge at 20,000 x g, at room temperature, for 1 min, or until a pellet was formed.</li>
 <li>Transfer between 20-40 &mu;l of each sample to a microplate reader.</li>
 <li>Read absorbance at 570 nm using a spectrophotometer.</li>
</ol>

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M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+debate+about+n-6+polyunsaturated+fatty+acid+recommendations+for+cardiovascular+health.">The debate about n-6 polyunsaturated fatty acid recommendations for cardiovascular health.</a> Journal of the American Diabetic Association. 110 (2), 201-204 (2010).</li><li>Rizzo, W. B., Phillips, M. W., 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=Adrenoleukodystrophy:+dietary+oleic+acid+lowers+hexacosanoate+levels.">Adrenoleukodystrophy: dietary oleic acid lowers hexacosanoate levels.</a> Annals of Neurology. 21 (3), 232-239 (1987).</li><li>Bozan, B., Temelli, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+composition+and+oxidative+stability+of+flax,+safflower+and+poppy+seed+and+seed+oil.">Chemical composition and oxidative stability of flax, safflower and poppy seed and seed oil.</a> Bioresource Tech. 99, 6354-6359 (2005).</li><li>Krein, S., Meldurm, H., Hawkins, S., Foy, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+benefits+of+conjugated+linoleic+acid+to+3-dimensional+wrinkle+morphology.">Clinical benefits of conjugated linoleic acid to 3-dimensional wrinkle morphology.</a> J. American Academy of Dermatology. 60 (3), AB30 (2009).</li><li>Yu, Y., Correll, P. H., Heuvel, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Conjugated+linoleic+acid+decreases+production+of+pro-inflammatory+products+in+macrophages:+Evidence+for+a+PPARy+dependent+mechanism.">Conjugated linoleic acid decreases production of pro-inflammatory products in macrophages: Evidence for a PPARy dependent mechanism.</a> Biochimica et Biophysica Acta. 1581 (3), 89-99 (2002).</li><li>Palombo, J., Ganguly, A., Bistrian, B., Menard, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+anti-proliferative+effects+of+biologically+active+isomers+of+conjugated+linoleic+acid+on+human+colorectal+and+prostatic+cancer+cells.">The anti-proliferative effects of biologically active isomers of conjugated linoleic acid on human colorectal and prostatic cancer cells.</a> Cancer Letters. 177, 163-172 (2002).</li><li>Granda, M., Sinclair, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fatty+acids+and+obesity.">Fatty acids and obesity.</a> Current Pharm. Design. 15 (36), 4117-4125 (2009).</li><li>Rosenstein, E., Kushner, L., Kramer, N., Kazandjian, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pilot+study+of+dietary+fatty+acid+supplementation+in+the+treatment+of+adult+periodontitis.">Pilot study of dietary fatty acid supplementation in the treatment of adult periodontitis.</a> Prostaglandins, Leukotrienes and Essential F.A. 68 (3), 213-218 (2003).</li><li>Ferretti, A., Flanagan, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antithromboxane+activity+of+dietary+alpha-linolenic+acid:+a+pilot+study.">Antithromboxane activity of dietary alpha-linolenic acid: a pilot study.</a> Prostaglandins Leukot. Essent. Fatty Acids. 54 (6), 451-455 (1995).</li><li>Arpita, C., Pradeep, K. D., Chowdhury, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+Fatty+Acids+and+Cholesterol+Present+in+Bile+on+Expression+of+Virulence+Factors+and+Motility+of+Vibrio+cholera.">Effect of Fatty Acids and Cholesterol Present in Bile on Expression of Virulence Factors and Motility of Vibrio cholera.</a> Infection and Immunity. 75 (4), 1946-1953 (2007).</li><li>Yamasaki, S., Asakura, M., Neogi, S. B., Hinenoya, A., Iwaoka, E., Aoki, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+virulence+potential+of+Vibrio+cholerae+by+natural+compounds.">Inhibition of virulence potential of Vibrio cholerae by natural compounds.</a> Indian J. Med. Res. 133 (2), 232-239 (2011).</li><li>Hendriksen, R. S., Price, L. 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=Population+Genetics+of+Vibrio+cholerae+from+Nepal+in+2010:+Evidence+on+the+origin+of+the+Haitian+outbreak.">Population Genetics of Vibrio cholerae from Nepal in 2010: Evidence on the origin of the Haitian outbreak.</a> mBio. 2 (4), 1-6 (2011).</li><li>Schaeffler, A., Gross, P., 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=Fatty+acid-induced+induction+of+Toll-like+receptor-4/nuclear+factor-kappa+B+pathway+in+adipocytes+links+nutritional+signaling+with+innate+immunity.">Fatty acid-induced induction of Toll-like receptor-4/nuclear factor-kappa B pathway in adipocytes links nutritional signaling with innate immunity.</a> Immunology. 126 (2), 233-245 (2009).</li></ol>

The authors of this study have no financial interest from the results of this study. Funding for this study was provided to FT by Kean University; however, FT is currently an employee at Kingsborough Community College.

Suggestion of Concentration of Fatty Acids and Cholera Toxin
While the exact mechanism of how fatty acids enhance mucosal immunity is unknown, several studies have attempted to investigate their beneficial effects. Our study aims to provide methodology to determine the maximum concentration of fatty acids that cells can tolerate as well as the maximum concentration of cholera toxin that cells can tolerate without a significant influence on cell survival.
To determ...

The health benefits of fatty acids, such as oleic, linoleic and linolenic acids have been and continue to be documented. For example, oleic acid helps facilitate penetration of lipophilic drugs in the body1,2, reduces coronary heart disease by 24% when substituted for saturated fatty acids3, and is used to treat metabolic diseases such as Adrenoleukodystrophy4 which is an X-linked genetic disorder of fatty acid metabolism. While a necessary precursor for arachidonic acid in mammals, linoleic acid (unlike oleic acid) is not synthesized by the body and must be obtained through outside sources such as by flax seed consumption.5 Studies show several beneficial health effects of linoleic acid such as: anti-aging properties for the skin;6 anti-inflammatory properties;7 reduced proliferation of colorectal and prostate carcinoma cells;8 and the ability to fight obesity and promotion of cardiovascular health.9 Linolenic acid plays a role in reducing periodontal inflammation,10 and modulating thromboxane and prostacyclin biosynthesis.11
Arpita12 studied the influence of bile fatty acids and cholesterol on V. cholerae's expression of virulence factors and motility. Yamasaki13 indicated that methanol extract from red chili peppers, and other naturally extracted compounds, can potentially decrease cholera toxin production. It is conceivable to consider the use of food products that are rich in the above fatty acids (such as flax seeds) in the prevention and alleviation of infectious disease such as cholera through providing mucosal immunity. We conducted investigations to solubilize fatty acids and to determine, using cell proliferation assays, the maximum concentration of fatty acids that human intestinal epithelial cells can tolerate without detrimental effects on cell viability. We hypothesized that oleic, linoleic and linolenic acids provide a beneficial effect on cell viability at lower concentrations, but that at higher concentrations they will be toxic to the cells. We also solubilized the cholera toxin and determined the maximum concentration of cholera toxin that BALB/C mouse macrophages can tolerate without a significant decrease in cell viability. We hypothesize a toxic effect of cholera toxin on cell viability even at very low level. The method of solubilizing a cholera toxin and using it to determine the maximum amount of the toxin that the cells can tolerate without a significant decrease in survivability provides an advantage for future studies. For example, a combination of the above methodologies can be used to determine whether fatty acids provide cells with mucosal immunity against cholera infections. To the best of our knowledge, this rational and methodology has not been explored.
 We discuss how our preliminary data can be used in later investigations to determine if oleic, linoleic and linolenic acids provide cells with mucosal immunity against cholera infection.

<table border="1">
		<tbody>
		 <tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Cells/Reagent</td>
		 </tr>
		 <tr>
			<td>Mus musculus macrophages</td>
			<td>ATCC</td>
			<td>ATCC RAW 264.7</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Dulbecco's Modified Eagle's Medium</td>
			<td>ATCC</td>
			<td>30-2002</td>
			<td></td>
		 </tr>
		 <tr>
			<td>L-glutamine</td>
			<td>ATCC</td>
			<td>30-2115</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Fetal bovine serum </td>
			<td>Bio-west</td>
			<td>S0250</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Antibiotic/antimycotic </td>
			<td>Hyclone</td>
			<td>SV3007901</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Human intestinal epithelial cells </td>
			<td>ATCC</td>
			<td>ATTC CCL-241</td>
			<td></td>
		 </tr>
		 <tr>
			<td>HybriCare media </td>
			<td>ATCC</td>
			<td>46-X</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Oleic Acid</td>
			<td>Sigma-Aldrich</td>
			<td>O1008</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Linoleic Acid</td>
			<td>Sigma-Aldrich</td>
			<td>L-1376</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Linolenic Acid</td>
			<td>Sigma-Aldrich</td>
			<td>L-2376</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Cholera toxin</td>
			<td>Sigma-Aldrich</td>
			<td>C8052</td>
			<td></td>
		 </tr>
		 <tr>
			<td></td>
			<td></td>
			<td></td>
			<td>Equipment</td>
		 </tr>
		 <tr>
			<td>BD Falcon 96-Well Cell Culture Plates</td>
			<td>BD Biosciences </td>
			<td>351172</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Spectrophotometer with Dynex Revelations 4.22 software</td>
			<td>Dynex</td>
			<td>91000101</td>
			<td></td>
		 </tr>
		</tbody>
 </table>

determination of tolerable fatty acids and cholera toxin concentrations using human intestinal epithelial cells and balb/c mouse macrophages

The positive role of fatty acids in the prevention and alleviation of non-human and human diseases have been and continue to be extensively documented. These roles include influences on infectious and non-infectious diseases including prevention of inflammation as well as mucosal immunity to infectious diseases. Cholera is an acute intestinal illness caused by the bacterium Vibrio cholerae. It occurs in developing nations and if left untreated, can result in death. While vaccines for cholera exist, they are not always effective and other preventative methods are needed. We set out to determine tolerable concentrations of three fatty acids (oleic, linoleic and linolenic acids) and cholera toxin using mouse BALB/C macrophages and human intestinal epithelial cells, respectively. We solubilized the above fatty acids and used cell proliferation assays to determine the concentration ranges and specific concentrations of the fatty acids that are not detrimental to human intestinal epithelial cell viability. We solubilized cholera toxin and used it in an assay to determine the concentration ranges and specific concentrations of cholera toxin that do not statistically decrease cell viability in BALB/C macrophages. 
We found the optimum fatty acid concentrations to be between 1-5 ng/&mu;l, and that for cholera toxin to be &lt; 30 ng per treatment. This data may aid future studies that aim to find a protective mucosal role for fatty acids in prevention or alleviation of cholera infections.

Determination of the Optimum Concentration of Fatty Acids
The optimum concentration for fatty acids is defined as the maximum concentration at which cell growth is comparable to or exceeds that of control cells, with relatively low variability in results. To determine the optimum concentration of oleic, linoleic and linolenic acids cells were initially treated with varying concentrations of each fatty acid in large increments and later with smaller increments. Figure 1 shows the ...

Watch this Scientific Journal Video about Determination of Tolerable Fatty Acids and Cholera Toxin Concentrations Using Human Intestinal Epithelial Cells and BALB/c Mouse Macrophages at JoVE.com

Determination of Tolerable Fatty Acids and Cholera Toxin Concentrations Using Human Intestinal Epithelial Cells and BALB/c Mouse Macrophages

We set out to determine tolerable concentrations of three fatty acids (oleic, linoleic and linolenic acids) and cholera toxin that did not significantly and adversely affect cell survival by solubilizing the fatty acids and the toxin and using them in cell survival assays.

The positive role of fatty acids in the prevention and alleviation of non-human and  human diseases have been and continue to be extensively documented. ...

determination-tolerable-fatty-acids-cholera-toxin-concentrations

Research

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Immunology and Infection

9.9K Views.  Kingsborough Community College. We set out to determine tolerable concentrations of three fatty acids (oleic, linoleic and linolenic acids) and cholera toxin that did not significantly and adversely affect cell survival by solubilizing the fatty acids and the toxin and using them in cell survival assays.

Video: Determination of Tolerable Fatty Acids and Cholera Toxin Concentrations Using Human Intestinal Epithelial Cells and BALB/c Mouse Macrophages

Application of a Mouse Ligated Peyer&#x2019;s Patch Intestinal Loop Assay to Evaluate Bacterial Uptake by M cells

The inside of our gut is inhabited with enormous number of commensal bacteria. The mucosal surface of the gastrointestinal tract is continuously exposed to them and occasionally to pathogens. The gut-associated lymphoid tissue (GALT) play a key role for induction of the mucosal immune response to these microbes1, 2. To initiate the mucosal immune response, the mucosal antigens must be transported from the gut lumen across the epithelial barrier into organized lymphoid follicles such as Peyer's patches. This antigen transcytosis is mediated by specialized epithelial M cells3, 4. M cells are atypical epithelial cells that actively phagocytose macromolecules and microbes. Unlike dendritic cells (DCs) and macrophages, which target antigens to lysosomes for degradation, M cells mainly transcytose the internalized antigens. This vigorous macromolecular transcytosis through M cells delivers antigen to the underlying organized lymphoid follicles and is believed to be essential for initiating antigen-specific mucosal immune responses. However, the molecular mechanisms promoting this antigen uptake by M cells are largely unknown. We have previously reported that glycoprotein 2 (Gp2), specifically expressed on the apical plasma membrane of M cells among enterocytes, serves as a transcytotic receptor for a subset of commensal and pathogenic enterobacteria, including Escherichia coli and Salmonella enterica serovar Typhimurium (S. Typhimurium), by recognizing FimH, a component of type I pili on the bacterial outer membrane 5. Here, we present a method for the application of a mouse Peyer's patch intestinal loop assay to evaluate bacterial uptake by M cells. This method is an improved version of the mouse intestinal loop assay previously described 6, 7. The improved points are as follows: 1. Isoflurane was used as an anesthetic agent. 2. Approximately 1 cm ligated intestinal loop including Peyer's patch was set up. 3. Bacteria taken up by M cells were fluorescently labeled by fluorescence labeling reagent or by overexpressing fluorescent protein such as green fluorescent protein (GFP). 4. M cells in the follicle-associated epithelium covering Peyer's patch were detected by whole-mount immunostainig with anti Gp2 antibody. 5. Fluorescent bacterial transcytosis by M cells were observed by confocal microscopic analysis. The mouse Peyer's patch intestinal loop assay could supply the answer what kind of commensal or pathogenic bacteria transcytosed by M cells, and may lead us to understand the molecular mechanism of how to stimulate mucosal immune system through M cells.

Application of a Mouse Ligated Peyer&amp;#8217;s Patch Intestinal Loop Assay to Evaluate Bacterial Uptake by M cells

M cells in a specialized follicle-associated epithelium covering Peyer&#x2019;s patches play an important role for the mucosal immunosurveillance in gut-associated lymphoid tissue. Here we described the evaluation method for bacterial transcytosis by M cells in vivo. This method provides a method to understand M-cell function in the immune system.

The inside of our gut is inhabited with enormous number of commensal bacteria. The mucosal surface of the gastrointestinal tract is continuously exposed ...

Isolation and Characterization of Dendritic Cells and Macrophages from the Mouse Intestine

Within the intestine reside unique populations of innate and adaptive immune cells that are involved in promoting tolerance towards commensal flora and food antigens while concomitantly remaining poised to mount inflammatory responses toward invasive pathogens1,2. Antigen presenting cells, particularly DCs and macrophages, play critical roles in maintaining intestinal immune homeostasis via their ability to sense and appropriately respond to the microbiota3-14. Efficient isolation of intestinal DCs and macrophages is a critical step in characterizing the phenotype and function of these cells. While many effective methods of isolating intestinal immune cells, including DCs and macrophages, have been described6,10,15-24, many rely upon long digestions times that may negatively influence cell surface antigen expression, cell viability, and/or cell yield. Here, we detail a methodology for the rapid isolation of large numbers of viable, intestinal DCs and macrophages. Phenotypic characterization of intestinal DCs and macrophages is carried out by directly staining isolated intestinal cells with specific fluorescence-labeled monoclonal antibodies for multi-color flow cytometric analysis. Furthermore, highly pure DC and macrophage populations are isolated for functional studies utilizing CD11c and CD11b magnetic-activated cell sorting beads followed by cell sorting.

Here, we detail a methodology for the rapid isolation of mouse intestinal dendritic cells (DCs) and macrophages. Phenotypic characterization of intestinal DCs and macrophages is performed using multi-color flow cytometric analysis while magnetic bead enrichment followed by cell sorting is used to yield highly pure populations for functional studies.

Within the intestine reside unique populations of innate and adaptive immune cells that are involved in promoting tolerance towards commensal flora and ...

Enteric Bacterial Invasion Of Intestinal Epithelial Cells In Vitro Is Dramatically Enhanced Using a Vertical Diffusion Chamber Model

The interactions of bacterial pathogens with host cells have been investigated extensively using in vitro cell culture methods. However as such cell culture assays are performed under aerobic conditions, these in vitro models may not accurately represent the in vivo environment in which the host-pathogen interactions take place. We have developed an in vitro model of infection that permits the coculture of bacteria and host cells under different medium and gas conditions. The Vertical Diffusion Chamber (VDC) model mimics the conditions in the human intestine where bacteria will be under conditions of very low oxygen whilst tissue will be supplied with oxygen from the blood stream. Placing polarized intestinal epithelial cell (IEC) monolayers grown in Snapwell inserts into a VDC creates separate apical and basolateral compartments. The basolateral compartment is filled with cell culture medium, sealed and perfused with oxygen whilst the apical compartment is filled with broth, kept open and incubated under microaerobic conditions. Both Caco-2 and T84 IECs can be maintained in the VDC under these conditions without any apparent detrimental effects on cell survival or monolayer integrity. Coculturing experiments performed with different C. jejuni wild-type strains and different IEC lines in the VDC model with microaerobic conditions in the apical compartment reproducibly result in an increase in the number of interacting (almost 10-fold) and intracellular (almost 100-fold) bacteria compared to aerobic culture conditions1. The environment created in the VDC model more closely mimics the environment encountered by C. jejuni in the human intestine and highlights the importance of performing in vitro infection assays under conditions that more closely mimic the in vivo reality. We propose that use of the VDC model will allow new interpretations of the interactions between bacterial pathogens and host cells.

Enteric Bacterial Invasion Of Intestinal Epithelial Cells In Vitro Is Dramatically Enhanced Using a Vertical Diffusion Chamber Model

Performing cell culture assays for investigating bacterial adhesion and invasion under aerobic conditions is usually unrepresentative of the in vivo environment. A Vertical Diffusion Chamber model allows study of interactions of the human pathogen Campylobacter jejuni with intestinal epithelial cells under more in vivo-like conditions, resulting in enhanced bacterial invasion.

The interactions of bacterial pathogens with host cells have been investigated extensively using in vitro cell culture methods. However as such cell ...

Isolation of Myeloid Dendritic Cells and Epithelial Cells from Human Thymus

In this protocol we provide a method to isolate dendritic cells (DC) and epithelial cells (TEC) from the human thymus. DC and TEC are the major antigen presenting cell (APC) types found in a normal thymus and it is well established that they play distinct roles during thymic selection. These cells are localized in distinct microenvironments in the thymus and each APC type makes up only a minor population of cells. To further understand the biology of these cell types, characterization of these cell populations is highly desirable but due to their low frequency, isolation of any of these cell types requires an efficient and reproducible procedure. This protocol details a method to obtain cells suitable for characterization of diverse cellular properties. Thymic tissue is mechanically disrupted and after different steps of enzymatic digestion, the resulting cell suspension is enriched using a Percoll density centrifugation step. For isolation of myeloid DC (CD11c+), cells from the low-density fraction (LDF) are immunoselected by magnetic cell sorting. Enrichment of TEC populations (mTEC, cTEC) is achieved by depletion of hematopoietic (CD45hi) cells from the low-density Percoll cell fraction allowing their subsequent isolation via fluorescence activated cell sorting (FACS) using specific cell markers. The isolated cells can be used for different downstream applications.

This protocol details a method to isolate antigen presenting cells from human thymus via different steps of enzymatic digestion of the tissue followed by density centrifugation of the single cell suspension and finally magnetic and/or FACS sorting of the cell populations of interest.

In this protocol we provide a method to isolate dendritic cells (DC) and epithelial cells (TEC) from the human thymus. DC and TEC are the major antigen ...

Using RNA-interference to Investigate the Innate Immune Response in Mouse Macrophages

Macrophages are key phagocytic innate immune cells. When macrophages encounter a pathogen, they produce antimicrobial proteins and compounds to kill the pathogen, produce various cytokines and chemokines to recruit and stimulate other immune cells, and present antigens to stimulate the adaptive immune response. Thus, being able to efficiently manipulate macrophages with techniques such as RNA-interference (RNAi) is critical to our ability to investigate this important innate immune cell. However, macrophages can be technically challenging to transfect and can exhibit inefficient RNAi-induced gene knockdown. In this protocol, we describe methods to efficiently transfect two mouse macrophage cell lines (RAW264.7 and J774A.1) with siRNA using the Amaxa Nucleofector 96-well Shuttle System and describe procedures to maximize the effect of siRNA on gene knockdown. Moreover, the described methods are adapted to work in 96-well format, allowing for medium and high-throughput studies. To demonstrate the utility of this approach, we describe experiments that utilize RNAi to inhibit genes that regulate lipopolysaccharide (LPS)-induced cytokine production.

In this protocol, we describe methods to efficiently transfect murine macrophage cell lines with siRNAs using the Amaxa Nucleofector 96-well Shuttle System, stimulate the macrophages with lipopolysaccharide, and monitor the effects on inflammatory cytokine production.

Macrophages are key phagocytic innate immune cells.  When macrophages encounter a pathogen, they produce antimicrobial proteins and compounds to kill the ...

Immunofluorescence Analysis of Stress Granule Formation After Bacterial Challenge of Mammalian Cells

Fluorescent imaging of cellular components is an effective tool to investigate host-pathogen interactions. Pathogens can affect many different features of infected cells, including organelle ultrastructure, cytoskeletal network organization, as well as cellular processes such as Stress Granule (SG) formation. The characterization of how pathogens subvert host processes is an important and integral part of the field of pathogenesis. While variable phenotypes may be readily visible, the precise analysis of the qualitative and quantitative differences in the cellular structures induced by pathogen challenge is essential for defining statistically significant differences between experimental and control samples. SG formation is an evolutionarily conserved stress response that leads to antiviral responses and has long been investigated using viral infections1. SG formation also affects signaling cascades and may have other still unknown consequences2. The characterization of this stress response to pathogens other than viruses, such as bacterial pathogens, is currently an emerging area of research3. For now, quantitative and qualitative analysis of SG formation is not yet routinely used, even in the viral systems. Here we describe a simple method for inducing and characterizing SG formation in uninfected cells and in cells infected with a cytosolic bacterial pathogen, which affects the formation of SGs in response to various exogenous stresses. Analysis of SG formation and composition is achieved by using a number of different SG markers and the spot detector plug-in of ICY, an open source image analysis tool.

We describe a method for the qualitative and quantitative analysis of stress granule formation in mammalian cells after the cells are challenged with bacteria and a number of different stresses. This protocol can be applied to investigate the cellular stress granule response in a wide range of host-bacterial interactions.

Fluorescent imaging of cellular components is an effective tool to investigate host-pathogen interactions. Pathogens can affect many different features of ...

Saturated Fatty Acids Induce Ceramide-associated Macrophage Cell Death

Macrophages highly express epidermal fatty acid-binding protein and adipose fatty acid-binding protein. They actively uptake saturated and unsaturated fatty acids, which might play a critical role in regulating their immune functions. Numerous studies have shown that various fatty acids, saturated or unsaturated, may possess different impacts on cell growth and function. However, the approaches used for fatty acid preparation vary, which may lead to non-physiological results. Serum albumin, a natural carrier for fatty acids in mammalian peripheral blood, is recommended for forming a conjugate complex with the sodium salt of fatty acids to study fatty acid function in mammalian cells, thus minimizing the toxicity of fatty acid soap. Thus, a simple, relatively quick heating and sonicating method is developed and presented here for BSA-fatty acid conjugate formation. We describe a protocol using saturated fatty acids, especially stearic acids to induce severe cell death in mouse bone-marrow derived macrophages. We further demonstrate that saturated fatty acid-induced cell death is positively associated with accumulated cellular ceramide levels. This method can be extended for studies of the impact of fatty acid on other mammalian cells.

We illustrate a straight-forward method to derive murine primary macrophages from bone marrow cells and a simple method to prepare BSA-fatty acid conjugates. Then we demonstrate that saturated fatty acids can induce macrophage cell death, and such cell death is positively associated with cellular accumulation of ceramide levels.

Macrophages highly express epidermal fatty acid-binding protein and adipose fatty acid-binding protein. They actively uptake saturated and unsaturated ...

Mouse- and Human-derived Primary Gastric Epithelial Monolayer Culture for the Study of Regeneration

In vitro studies of gastric wound repair typically involves the use of gastric cancer cell lines in a scratch-wound assay of cellular proliferation and migration. One critical limitation of such assays, however, is their homogenous assortment of cellular types. Repair is a complex process which demands the interaction of several cell types. Therefore, to study a culture devoid of cellular subtypes, is a concern that must be overcome if we are to understand the repair process. The gastric organoid model may alleviate this issue whereby the heterogeneous collection of cell types closely reflects that of the gastric epithelium or other native tissues in vivo. Demonstrated here is a novel, in vitro scratch-wound assay derived from human or mouse 3-dimensional organoids which can then be transferred to a gastric epithelial monolayer as either intact organoids or as a single cell suspension of dissociated organoids. The goal of the protocol is to establish organoid-derived gastric epithelial monolayers that can be used in a novel scratch-wound assay system to study gastric regeneration.

Here we describe a protocol for establishing and culturing human- and mouse-derived 3-dimensional (3D) gastric organoids, and the method for the transfer of 3D organoids to a 2-dimensional monolayer. The use of the gastric epithelial monolayer as a novel scratch-wound assay for regeneration studies is also described.

In vitro studies of gastric wound repair typically involves the use of gastric cancer cell lines in a scratch-wound assay of cellular proliferation and ...

Induction of Drug-Induced, Autoimmune Hepatitis in BALB/c Mice for the Study of Its Pathogenic Mechanisms

Drug-induced autoimmune hepatitis (DIH) is the most common hepatic drug-induced hypersensitization process observed in approximately 9 to 12% of patients with autoimmune hepatitis. The overwhelming majority of patients with DIH are women. The underlying mechanisms of these sex differences in prevalence are unclear because of the paucity of animal models that mimic human disease. Even so, underlying mechanisms are widely believed to be associated with human leukocyte antigen haplotypes and sex hormones. In contrast, using a DIH mouse model, we have uncovered that IL-4 initiated&#160;CD4+ T cells directed against an epitope of cytochrome P450 2E1 induces influx of neutrophils, macrophages and mast cells into the livers of female BALB/c mice. Using this model, we have also shown that IL-33-induced FoxP3+regulatory T cells confer protection against DIH in female and male mice. This DIH model is induced by immunizing mice with an epitope of CYP2E1 that has been covalently altered with a drug metabolite that has been associated with DIH. This epitope is recognized by patients with DIH. Our method induces robust and reproducible hepatitis and autoantibodies that can be utilized to study the pathogenesis of DIH. While in vivo studies can cause undue pain and distress in mice when done improperly, the advantage of an in vivo model is the ability to evaluate the pathogenesis of disease in a large number of mice. Additionally, biological effects of the altered liver proteins can be studied using invasive procedures. The addition of in vitro studies to the experimental design allows rapid repetition and mechanistic analysis at a cellular level. Thus, we will demonstrate our model protocol and how it can be utilized to study in vivo and in vitro mechanisms of DIH.

We describe an in vivo immunization, translational hepatitis model in BALB/c mice that can be utilized to study the pathogenesis of drug-induced autoimmune hepatitis including sex differences seen in this disease. We will describe how this model demonstrates reproducible analyses using in vivo and in vitro experimental techniques.

Drug-induced autoimmune hepatitis (DIH) is the most common hepatic drug-induced hypersensitization process observed in approximately 9 to 12% of patients ...

Using Human Induced Pluripotent Stem Cell-derived Intestinal Organoids to Study and Modify Epithelial Cell Protection Against Salmonella and Other Pathogens

The intestinal &#8216;organoid&#8217; (iHO) system, wherein 3-D structures representative of the epithelial lining of the human gut can be produced from human induced pluripotent stem cells (hiPSCs) and maintained in culture, provides an exciting opportunity to facilitate the modeling of the epithelial response to enteric infections. In vivo, intestinal epithelial cells (IECs) play a key role in regulating intestinal homeostasis and may directly inhibit pathogens, although the mechanisms by which this occurs are not fully elucidated. The cytokine interleukin-22 (IL-22) has been shown to play a role in the maintenance and defense of the gut epithelial barrier, including inducing a release of antimicrobial peptides and chemokines in response to infection.
We describe the differentiation of healthy control hiPSCs into iHOs via the addition of specific cytokine combinations to their culture medium before embedding them into a basement membrane matrix-based prointestinal culture system. Once embedded, the iHOs are grown in media supplemented with Noggin, R-spondin-1, epidermal growth factor (EGF), CHIR99021, prostaglandin E2, and Y-27632 dihydrochloride monohydrate. Weekly passages by manual disruption of the iHO ultrastructure lead to the formation of budded iHOs, with some exhibiting a crypt/villus structure. All iHOs demonstrate a differentiated epithelium consisting of goblet cells, enteroendocrine cells, Paneth cells, and polarized enterocytes, which can be confirmed via immunostaining for specific markers of each cell subset, transmission electron microscopy (TEM), and quantitative PCR (qPCR). To model infection, Salmonella enterica serovar Typhimurium SL1344 are microinjected into the lumen of the iHOs and incubated for 90 min at 37 &#176;C, and a modified gentamicin protection assay is performed to identify the levels of intracellular bacterial invasion. Some iHOs are also pretreated with recombinant human IL-22 (rhIL-22) prior to infection to establish whether this cytokine is protective against Salmonella infection.

Using Human Induced Pluripotent Stem Cell-derived Intestinal Organoids to Study and Modify Epithelial Cell Protection Against Salmonella and Other Pathogens

Human induced pluripotent stem cell (hiPSC)-derived intestinal organoids offer exciting opportunities to model enteric diseases in vitro. We demonstrate the differentiation of hiPSCs into intestinal organoids (iHOs), the stimulation of these iHOs with cytokines, and the microinjection of Salmonella Typhimurium into the iHO lumen, enabling the study of an epithelial invasion by this pathogen.

The intestinal &#8216;organoid&#8217; (iHO) system, wherein 3-D structures representative of the epithelial lining of the human gut can be produced from ...