Name: the wincf model - an inexpensive and tractable microcosm of a mucus plugged bronchiole to study the microbiology of lung infections
Uploaded: 2017-05-08T14:00:00
Description: Watch this Scientific Journal Video about The WinCF Model - An Inexpensive and Tractable Microcosm of a Mucus Plugged Bronchiole to Study the Microbiology of Lung Infections at JoVE.com

The authors would like to acknowledge Vertex Pharmaceuticals and the Cystic Fibrosis Research Innovation Award for funding R. Quinn and the NIH/NIAID for funding grant 1 U01 AI124316-01, a systems biology approach to treatment of multi-drug resistant pathogens. We would also like to thank the Department of Mechanical and Aerospace Engineering at UCSD's undergraduate mechanical engineering senior design course for facilitating the collaboration with the engineering aspects of this work.

1. Preparation of Stocks for the Artificial Sputum Media
<ol>
	<li>Create a 5% mucin solution. Add 1.0 g of dehydrated pig stomach mucin to 20 mL of deionized water. Autoclave the resulting solution. 
	NOTE: The mucin sterilization will destroy its inherent structure; other methods to sterilize the mucin in its dry form include UV sterilization and irradiation. These methods have not been extensively used for the WinCF system however.</li>
	<li>Add 2.2 g of KCl to 50 mL of deionized water and allow for dissolution...

<ol>
	<li>Quinn, R. 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=A+Winogradsky-based+culture+system+shows+an+association+between+microbial+fermentation+and+cystic+fibrosis+exacerbation.">A Winogradsky-based culture system shows an association between microbial fermentation and cystic fibrosis exacerbation.</a> ISME J . 9, 1024-1038 (2015).</li><li>Quinton, P. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cystic+fibrosis:+impaired+bicarbonate+secretion+and+mucoviscidosis.">Cystic fibrosis: impaired bicarbonate secretion and mucoviscidosis.</a> Lancet. 372 (9636), 415-417 (2008).</li><li>Harrison, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microbial+ecology+of+the+cystic+fibrosis+lung.">Microbial ecology of the cystic fibrosis lung.</a> Microbiology. 153 (Pt 4), 917-923 (2007).</li><li>Caverly, L. J., Zhao, J., LiPuma, J. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cystic+fibrosis+lung+microbiome:+Opportunities+to+reconsider+management+of+airway+infection.">Cystic fibrosis lung microbiome: Opportunities to reconsider management of airway infection.</a> Pediatr pulmonol. 50, S31-S38 (2015).</li><li>Blainey, P. C., Milla, C. E., Cornfield, D. N., Quake, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+analysis+of+the+human+airway+microbial+ecology+reveals+a+pervasive+signature+for+cystic+fibrosis.">Quantitative analysis of the human airway microbial ecology reveals a pervasive signature for cystic fibrosis.</a> Sci Transl Med. 4 (153), 153ra130 (2012).</li><li>Willner, D., 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=Spatial+distribution+of+microbial+communities+in+the+cystic+fibrosis+lung.">Spatial distribution of microbial communities in the cystic fibrosis lung.</a> ISME J. 6 (2), 471-474 (2012).</li><li>Delhaes, 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=The+airway+microbiota+in+cystic+fibrosis:+a+complex+fungal+and+bacterial+community--implications+for+therapeutic+management.">The airway microbiota in cystic fibrosis: a complex fungal and bacterial community--implications for therapeutic management.</a> PloS one. 7 (4), e36313 (2012).</li><li>Rogers, G. 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=D.+Bacterial+diversity+in+cases+of+lung+infection+in+cystic+fibrosis+patients:+16S+ribosomal+DNA+(rDNA)+length+heterogeneity+PCR+and+16S+rDNA+terminal+restriction+fragment+length+polymorphism+profiling.">D. Bacterial diversity in cases of lung infection in cystic fibrosis patients: 16S ribosomal DNA (rDNA) length heterogeneity PCR and 16S rDNA terminal restriction fragment length polymorphism profiling.</a> J clin microbiol. 41 (8), 3548-3558 (2003).</li><li>Stenbit, A. E., Flume, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulmonary+exacerbations+in+cystic+fibrosis.">Pulmonary exacerbations in cystic fibrosis.</a> Curr Opin Pulm Med. 17 (6), 442-447 (2011).</li><li>Twomey, K. 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=Microbiota+and+metabolite+profiling+reveal+specific+alterations+in+bacterial+community+structure+and+environment+in+the+cystic+fibrosis+airway+during+exacerbation.">Microbiota and metabolite profiling reveal specific alterations in bacterial community structure and environment in the cystic fibrosis airway during exacerbation.</a> PloS one. 8 (12), e82432 (2013).</li><li>Carmody, L. 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=Changes+in+cystic+fibrosis+airway+microbiota+at+pulmonary+exacerbation.">Changes in cystic fibrosis airway microbiota at pulmonary exacerbation.</a> Ann. Am. Thorac. Soc. 10 (3), 179-187 (2013).</li><li>Worlitzsch, D., 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+reduced+mucus+oxygen+concentration+in+airway+Pseudomonas+infections+of+cystic+fibrosis+patients.">Effects of reduced mucus oxygen concentration in airway Pseudomonas infections of cystic fibrosis patients.</a> J. Clin. Invest. 109 (3), 317-325 (2002).</li><li>Cowley, E. S., Kopf, S. H., LaRiviere, A., Ziebis, W., Newman, D. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pediatric+Cystic+Fibrosis+Sputum+Can+Be+Chemically+Dynamic,+Anoxic,+and+Extremely+Reduced+Due+to+Hydrogen+Sulfide+Formation.">Pediatric Cystic Fibrosis Sputum Can Be Chemically Dynamic, Anoxic, and Extremely Reduced Due to Hydrogen Sulfide Formation.</a> mBio. 6 (4), e00767-e00715 (2015).</li><li>Sriramulu, D. D., L&#252;nsdorf, H., Lam, J. S., R&#246;mling, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microcolony+formation:+a+novel+biofilm+model+of+Pseudomonas+aeruginosa+for+the+cystic+fibrosis+lung.">Microcolony formation: a novel biofilm model of Pseudomonas aeruginosa for the cystic fibrosis lung.</a> J. Med. Microbiol. 54 (Pt 7), 667-676 (2005).</li><li>Quinn, R. 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=Biogeochemical+forces+shape+the+composition+and+physiology+of+polymicrobial+communities+in+the+cystic+fibrosis+lung.">Biogeochemical forces shape the composition and physiology of polymicrobial communities in the cystic fibrosis lung.</a> mBio. 5 (2), (2014).</li></ol>

The microbiological makeup of a lung with CF contains a great variety of organisms, but the conditions within the lung likely have a significant influence on what kinds of microbes can survive and thrive13,15. Specific mechanisms through which these conditions change and the exact effects they have on the lung microbiome are generally unclear at present. In this experimental method, we present an analysis of microbiological changes based upon manipulated chemical...

The method described in this manuscript is called the WinCF system1. The overall goal of WinCF is to provide an experimental setup capable of simulating the environment of a mucus-filled lung bronchiole. This will allow for a tractable system to study microbial pathogens of lung diseases with a mucus hypersecretion phenotype including cystic fibrosis (CF), chronic obstructive pulmonary disease (COPD), asthma and others. The procedure was designed specifically for the study of CF, which is characterized by mutations that cause lung secretions to become thick and hard to clear, eventually filling bronchioles and other small passageways with mucus2. Such blockages in the lung inhibit gas exchange because inhaled air is no longer able to reach many alveoli and also provide a habitat for bacterial colonization3,4. The inability to prevent microbial growth in the excessive lung mucus eventually leads to the development of complex chronic infections of the airway. These communities contain a variety of organisms, including viruses, fungi, and bacteria like Pseudomonas aeruginosa, all interacting with one another5,6,7,8. The activity of the CF lung microbiome is believed to be involved in flares of symptoms called pulmonary exacerbations1,9,10,11. WinCF enables study of the microbial community behavior around these exacerbations and is now being expanded to act as a base experimental system to study lung microbial ecology. Traditionally, exacerbations have been studied through direct analysis of samples taken from the lung. Many confounding factors make direct analysis of microbial behavior in lungs challenging, with the WinCF system, many of these factors are removed and the behavior of the lung microbiome can be studied more directly, allowing for finer analysis of bacterial activity in a mucus-plugged bronchiole.
The WinCF system provides a method to grow and analyze bacteria in a manner that effectively mimics the lung environment. Traditional methods for growing lung bacteria often involved culturing samples on traditional agar plates. These methods leave the samples open to atmospheric oxygen, neglecting to account for the hypoxic and often anoxic conditions found in lung bronchioles plugged with mucus12,13. Culturing on agar under aerobic conditions is nothing like the environment of the CF lung and can mislead clinicians and researchers concerning the behavior of the pathogens that they are trying to treat. Additionally, the nutrients available to bacteria on agar plates are dissimilar to those available in actual sputum, which is accounted for in WinCF by utilizing artificial sputum media (ASM). As shown by the Pseudomonas cultures in Sriramulu et al.14, ASM includes a specific set of components that mimics the resources available to sputum microbes and also replicates the physical consistency of sputum. Because a diseased lung has a specific microbiome, the study of such microorganisms should ideally take place in the specific conditions of the lung as well.
The WinCF system enables rapid analysis and easy manipulation of the experimental conditions to observe microbial changes similar to how they would occur in an actual lung bronchiole. This technique allows for the inoculation of a myriad of related sample types including sputum, saliva, other body secretions and pure or mixed bacterial cultures. The nature of the experimental setup allows for immediate visual interpretation of the microbial community behavior and is designed to enable easy downstream application of a multitude of microbiological and omics procedures. Such studies are important because bacterial community composition changes based upon the physiochemical conditions of their environment. With WinCF the chemical conditions of the media can be manipulated to analyze the effects on bacterial activity. For example, the acidity of the media can be altered prior to inoculation with a sample. After incubation, the bacterial activity in each of these conditions can be directly compared, and conclusions can be drawn about how bacteria in those sputum samples behave in response to varying pH. Here, we outline the procedures for applying the WinCF system and examples of how the media chemistry can be manipulated to study the effects on the lung microbiome.

<table border="0" cellpadding="0" cellspacing="0" width="595">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Color-Coded Capillary Tubes</td>
			<td style="width:93px;">Fisher Scientific</td>
			<td style="width:119px;">22-260943</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Cha-seal Tube Sealing Compound</td>
			<td style="width:93px;">Kimble-Chase</td>
			<td align="right" style="width:119px;">43510</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Mucin from porcine stomach</td>
			<td style="width:93px;">Sigma</td>
			<td style="width:119px;">M1778</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Ferritin, cationized from horse spleen</td>
			<td style="width:93px;">Sigma</td>
			<td style="width:119px;">F7879</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Salmon sperm DNA Sodium salt (sonified)</td>
			<td style="width:93px;">AppliChem Panreac</td>
			<td>A2159</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">MEM Nonessential Amino Acids</td>
			<td style="width:93px;">Corning cellgro</td>
			<td style="width:119px;">25-025-CI</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">MEM Amino Acids</td>
			<td style="width:93px;">Cellgro</td>
			<td style="width:119px;">25-030-CI</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Egg Yolk Emulsion, 50%</td>
			<td style="width:93px;">Dalynn Biologicals</td>
			<td style="width:119px;">VE30-100</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Potassium Chloride</td>
			<td style="width:93px;">Fisher Scientific</td>
			<td style="width:119px;">P2157500</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Sodium Chloride</td>
			<td style="width:93px;">Fisher Scientific</td>
			<td style="width:119px;">S271500</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">15mL centriguge tubes with Printed Graduations and Flat Caps</td>
			<td style="width:93px;">VWR</td>
			<td style="width:119px;">89039-666</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">50mL centrifuge tubes with Printed Graduations and Flat Caps</td>
			<td style="width:93px;">VWR</td>
			<td style="width:119px;">89039-656</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1.5mL microcentrifuge tubes</td>
			<td style="width:93px;">Corning</td>
			<td style="width:119px;">MCT-150-R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">2.0mL microcentrifuge tubes</td>
			<td style="width:93px;">Corning</td>
			<td style="width:119px;">MCT-200-C</td>
			<td></td>
		</tr>
	</tbody>
</table>

the wincf model - an inexpensive and tractable microcosm of a mucus plugged bronchiole to study the microbiology of lung infections

Many chronic airway diseases result in mucus plugging of the airways. Lungs of an individual with cystic fibrosis are an exemplary case where their mucus-plugged bronchioles create a favorable habitat for microbial colonization. Various pathogens thrive in this environment interacting with each other and driving many of the symptoms associated with CF disease. Like any microbial community, the chemical conditions of their habitat have a significant impact on the community structure and dynamics. For example, different microorganisms thrive in differing levels of oxygen or other solute concentrations. This is also true in the CF lung, where oxygen concentrations are believed to drive community physiology and structure. The methods described here are designed to mimic the lung environment and grow pathogens in a manner more similar to that from which they cause disease. Manipulation of the chemical surroundings of these microbes is then used to study how the chemistry of lung infections governs its microbial ecology. The method, called the WinCF system, is based on artificial sputum medium and narrow capillary tubes meant to provide an oxygen gradient similar to that which exists in mucus-plugged bronchioles. Manipulating chemical conditions, such as the media pH of the sputum or antibiotics pressure, allows for visualization of the microbiological differences in those samples using colored indicators, watching for gas or biofilm production, or extracting and sequencing the nucleic acid contents of each sample.

Microbiological growth across the various chemical conditions induced within the samples varied dramatically in some cases and more subtly in others. Many changes in activity were visual in nature, being readily apparent as soon as the incubation period ended. In the example of pH manipulation, the samples across the pH spectrum varied greatly as shown by multiple factors that became apparent after incubation. When no sputum samples were added to the media, the only change exhibited acros...

Watch this Scientific Journal Video about The WinCF Model - An Inexpensive and Tractable Microcosm of a Mucus Plugged Bronchiole to Study the Microbiology of Lung Infections at JoVE.com

The WinCF Model - An Inexpensive and Tractable Microcosm of a Mucus Plugged Bronchiole to Study the Microbiology of Lung Infections

The mucus plugged airways of cystic fibrosis (CF) patients are an ideal environment for microbial pathogens to thrive. The manuscript describes a novel method for studying the CF lung microbiome in an environment that mimics where they cause disease and how alterations of chemical conditions can drive microbial dynamics.

Many chronic airway diseases result in mucus plugging of the airways. Lungs of an individual with cystic fibrosis are an exemplary case where their ...

The overall goal of this procedure is to mimic the lung environment and grow pathogens in a manner more similar to that from which they cause disease. This method can help answer key questions in the airway microbiology field Such as, how diverse bacterial pathogens interact in a cystic fibrosis lung. The main advantage of this technique is that it allows for easy manipulation of experimental conditions.To observe microbial responses similar to how they would occur in an actual lung bronchial. Demonstrating the procedure, will be Will Comstock from our laboratory. To prepare artificial sputum medium, Combine 16 milliliters of previous prepared muceum stock solution, Two milliliters of potassium chloride stock solution, two milliliters of sodium chloride stock solution, 200 microliters of egg yolk emulsion, 5.6 milliliters of DNA stock solution, 120 microliters of ferritin stock solution, 5.78 milliliters of essential amino acid solution, 5.78 milliliters of non-essential amino acid solution, and 2.44 milliliters of sterile water.The careful creation of sterile artificial sputum medium is extremely important. As any contamination can alter bacterial activity in the incubated capillary tubes, further down the line. After gently shaking to mix, pipette five milliliters of the medium into eight sterile 15 milliliter centrifuge tubes.The medium can now be modified to achieve the desired chemical conditions. For instance, the media shown here, have had their PH altered and dyes added to reflect their different acidities. Next, under a sterile bio-hood, add 900 microliters of medium to each of eight sterile 1.5 milliliter microcentrifuge tubes.Homogenize previously acquired sputum samples by using a three milliliter syringe to repeatedly withdraw and eject the sputum until it is of a smooth consistency. Add 100 microliters of the homogenized sputum to each of the eight microcentrifuge tubes. Then vortex the tubes to sufficiently mix.Label eight more sterile 15 milliliter centrifuge tubes according to the microcentrifuge tubes of medium previously prepared. These will be the incubation tubes. Use 70%ethanol solution to sterilize a paper towel and allow it to dry.Tear the towel into pieces about four square inches each. Then crumble one piece in the bottom of each incubation tube. With one clump of paper at the bottom of each incubation tube, use 1 milliliter of sterile water to slightly dampen each clump to create a humid environment inside the tube.For each tube of medium, fill three glass capillary tubes with medium by holding one end of the tube in the medium and horizontal tilting it. Allowing capillary action to guide the medium into the tube. Stop the filling by gently placing a gloved finger over the open end of the tube, and then seal the other end of the tube by pressing it down into a block of capillary putty sealant.Place each set of three capillary tubes into 15 milliliter incubation tubes putty sealed side down. Then cap the tubes and insure they are labeled. These three capillary tubes are for replication of each control condition.When all incubation tubes are filled with their designated capillary tubes. Place the racks at 37 degrees Celsius such that the tubes will be incubated horizontally so that any gas generated does not escape through the open end. Incubate the tubes for 48 hours.Remove the tubes from the incubator making sure to keep them horizontal. Carefully the capillary tubes out of the incubation tubes, keeping each set of three separate from other sets. Arrange the capillary tubes next to each other on a light box all lined up so the contents of the tubes are visible and illuminated from below.Weave a gap every three tubes to separate different chemical conditions Next Focus the camera on the tubes directly above them such that all tubes are visible in the field of view and light from the light box provides sufficient contrast and visualization of the color of the tube dyes. To extract the contents of the tubes for downstream analysis, remove one set of triplicate capillaries from the light box at a time. Insert a 25 gauge 0.5 inch blunt ended needle into the plugged end of the capillary tube to break the seal.Then turn the capillary tube upside down to allow the medium to drip from the top portion of the into a 1.5 milliliter micro centrifuge tube. If the medium does not drip out, use a to 200 microliter pipette to expel the medium out of the tube by pressing down on a pipette plunger when it is inserted into the end of the capillary tube. As shown here, when no sputum samples were added to the medium, the only change exhibited across the pH spectrum after 48 hours of incubation was a slight decrease in medium volume resulting from minor evaporation.Inoculated capillary tubes showed changes in volume, the appearance of gas bubbles, altered coloration, and the appearance of opaque deposits. These results show that bacteria and other microbes contained within the added sputum, are able to grow and change within the artificial medium. Following incubation, other methods like metabolomics and DNA sequencing can be performed to answer additional questions about the behavior of the microbes that grow in the capillary tubes.The winCF system is a novel method to study the activity of the lung microbiome;important for many diseases including CF, COPD, asthma, and others.

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Research

JoVE Journal

Immunology and Infection

Tractable Mammalian Cell Infections with Protozoan-primed Bacteria

Many intracellular bacterial pathogens use freshwater protozoans as a natural reservoir for proliferation in the environment. Legionella pneumophila, the causative agent of Legionnaires' pneumonia, gains a pathogenic advantage over in vitro cultured bacteria when first harvested from protozoan cells prior to infection of mammalian macrophages. This suggests that important virulence factors may not be properly expressed in vitro. We have developed a tractable system for priming L. pneumophila through its natural protozoan host Acanthamoeba castellanii prior to mammalian cell infection. The contribution of any virulence factor can be examined by comparing intracellular growth of a mutant strain to wild-type bacteria after protozoan priming. GFP-expressing wild-type and mutant L. pneumophila strains are used to infect protozoan monolayers in a priming step and allowed to reach late stages of intracellular growth. Fluorescent bacteria are then harvested from these infected cells and normalized by spectrophotometry to generate comparable numbers of bacteria for a subsequent infection into mammalian macrophages. For quantification, live bacteria are monitored after infection using fluorescence microscopy, flow cytometry, and by colony plating. This technique highlights and relies on the contribution of host cell-dependent gene expression by mimicking the environment that would be encountered in a natural acquisition route. This approach can be modified to accommodate any bacterium that uses an intermediary host as a means for gaining a pathogenic advantage.

This technique provides a method to harvest, normalize and quantify intracellular growth of bacterial pathogens that are pre-cultivated in natural protozoan host cells prior to infections of mammalian cells. This method can be modified to accommodate a wide variety of host cells for the priming stage as well as target cell types.

Many intracellular bacterial pathogens use freshwater protozoans as a natural reservoir for proliferation in the environment. Legionella pneumophila, the ...

An In vitro Model to Study Heterogeneity of Human Macrophage Differentiation and Polarization

Monocyte-derived macrophages represent an important cell type of the innate immune system. Mouse models studying macrophage biology suffer from the phenotypic and functional differences between murine and human monocyte-derived macrophages. Therefore, we here describe an in vitro model to generate and study primary human macrophages. Briefly, after density gradient centrifugation of peripheral blood drawn from a forearm vein, monocytes are isolated from peripheral blood mononuclear cells using negative magnetic bead isolation. These monocytes are then cultured for six days under specific conditions to induce different types of macrophage differentiation or polarization. The model is easy to use and circumvents the problems caused by species-specific differences between mouse and man. Furthermore, it is closer to the in vivo conditions than the use of immortalized cell lines. In conclusion, the model described here is suitable to study macrophage biology, identify disease mechanisms and novel therapeutic targets. Even though not fully replacing experiments with animals or human tissues obtained post mortem, the model described here allows identification and validation of disease mechanisms and therapeutic targets that may be highly relevant to various human diseases.

An In vitro Model to Study Heterogeneity of Human Macrophage Differentiation and Polarization

Monocyte-derived macrophages are important cells of the innate immune system. Here, we describe an easy to use in vitro model to generate these cells. Using gradient centrifugation, negative bead isolation and specific cell culture conditions, monocyte-derived macrophages can be generated for phenotypic and functional studies.

Monocyte-derived macrophages represent an important cell type of the innate immune system. Mouse models studying macrophage biology suffer from the ...

An Experimental Model to Study Tuberculosis-Malaria Coinfection upon Natural Transmission of Mycobacterium tuberculosis and Plasmodium berghei

Coinfections naturally occur due to the geographic overlap of distinct types of pathogenic organisms. Concurrent infections most likely modulate the respective immune response to each single pathogen and may thereby affect pathogenesis and disease outcome. Coinfected patients may also respond differentially to anti-infective interventions. Coinfection between tuberculosis as caused by mycobacteria and the malaria parasite Plasmodium, both of which are coendemic in many parts of sub-Saharan Africa, has not been studied in detail. In order to approach the challenging but scientifically and clinically highly relevant question how malaria-tuberculosis coinfection modulate host immunity and the course of each disease, we established an experimental mouse model that allows us to dissect the elicited immune responses to both pathogens in the coinfected host. Of note, in order to most precisely mimic naturally acquired human infections, we perform experimental infections of mice with both pathogens by their natural routes of infection, i.e. aerosol and mosquito bite, respectively.

An Experimental Model to Study Tuberculosis-Malaria Coinfection upon Natural Transmission of Mycobacterium tuberculosis and Plasmodium berghei

Tuberculosis and malaria are two of the most prevalent infections in humans and major causes of morbidity and mortality in impoverished populations in the tropics. We established an experimental model system to study outcome of malaria-tuberculosis coinfection in mice after challenge with both pathogens via their natural route of infection.

Coinfections naturally occur due to the geographic overlap of distinct types of pathogenic organisms. Concurrent infections most likely modulate the ...

Humanized Mouse Model to Study Bacterial Infections Targeting the Microvasculature

Neisseria meningitidis causes a severe, frequently fatal sepsis when it enters the human blood stream. Infection leads to extensive damage of the blood vessels resulting in vascular leak, the development of purpuric rashes and eventual tissue necrosis. Studying the pathogenesis of this infection was previously limited by the human specificity of the bacteria, which makes in vivo models difficult. In this protocol, we describe a humanized model for this infection in which human skin, containing dermal microvessels, is grafted onto immunocompromised mice. These vessels anastomose with the mouse circulation while maintaining their human characteristics. Once introduced into this model, N. meningitidis adhere exclusively to the human vessels, resulting in extensive vascular damage, inflammation and in some cases the development of purpuric rash. This protocol describes the grafting, infection and evaluation steps of this model in the context of N. meningitidis infection. The technique may be applied to numerous human specific pathogens that infect the blood stream.

Neisseria meningitidis is a human specific pathogen that infects blood vessels. In this protocol human microvessels are introduced into a mouse by grafting human skin onto immunocompromised mice. Bacteria adhere extensively to the human vessels, leading to vascular damage and development of the purpuric rash typically observed in human cases.

Neisseria meningitidis causes a severe, frequently fatal sepsis when it enters the human blood stream. Infection leads to extensive damage of the blood ...

Human Placental and Decidual Organ Cultures to Study Infections at the Maternal-fetal Interface

The placenta shows a large degree of interspecies anatomic variability. To best understand biology and pathophysiology of the human placenta, it is imperative to design experiments using human cells and tissues. An advantage of organ culture is maintenance of three-dimensional (3D) structural organization and extracellular matrix. The goal of the method described here is successful establishment of ex vivo human gestational tissue organ cultures and their healthy culture maintenance for 72-96 hr. The protocol details the immediate processing of research-consented, placental and decidual specimens fresh from the operating suite. These are abundant specimens that would otherwise be discarded. Detailed instructions on the sterile collection of these samples, including morphologic details on how to select appropriate tissues to establish 3D organ cultures, is provided. Placental villous and decidual tissues are microdissected into 2-3 mm3 pieces and placed separately on matrix-lined transwell filters and cultured for several days. Villous and decidual organ cultures are well suited for the study of human host-pathogen interaction. As compared to other model organisms, these human cultures are particularly advantageous to examine mechanism of infection for pathogens that demonstrate variable patterns of host specificity. As an example, we demonstrate infection of placental and decidual organ cultures with the clinically relevant, facultative intracellular bacterial pathogen Listeria monocytogenes.

A simple method to establish primary human placental (villous) and decidual organ cultures is described. Villous and decidual organ cultures are invaluable tools for studying pathogenesis at the human maternal-fetal interface. Infection with the facultative intracellular bacterium Listeria monocytogenes is demonstrated.

The placenta shows a large degree of interspecies anatomic variability. To best understand biology and pathophysiology of the human placenta, it is ...

Development of an Antigen-driven Colitis Model to Study Presentation of Antigens by Antigen Presenting Cells to T Cells

Inflammatory bowel disease (IBD) is a chronic inflammation which affects the gastrointestinal tract (GIT). One of the best ways to study the immunological mechanisms involved during the disease is the T cell transfer model of colitis. In this model, immunodeficient mice (RAG-/- recipients) are reconstituted with naive CD4+ T cells from healthy wild type hosts.
This model allows examination of the earliest immunological events leading to disease and chronic inflammation, when the gut inflammation perpetuates but does not depend on a defined antigen. To study the potential role of antigen presenting cells (APCs) in the disease process, it is helpful to have an antigen-driven disease model, in which a defined commensal-derived antigen leads to colitis. An antigen driven-colitis model has hence been developed. In this model OT-II CD4+ T cells, that can recognize only specific epitopes in the OVA protein, are transferred into RAG-/- hosts challenged with CFP-OVA-expressing E. coli. This model allows the examination of interactions between APCs and T cells in the lamina propria.

In this antigen-driven colitis model, OT-II CD4+ T cells expressing a red fluorescent protein were adoptively transferred into RAG-/- mice that express a green fluorescent protein in mononuclear phagocytes (MPs). The hosts were challenged with Escherichia coli (E.coli) expressing the ovalbumin protein (OVA) fused to a cyan fluorescent protein (CFP).

Inflammatory bowel disease (IBD) is a chronic inflammation which affects the gastrointestinal tract (GIT). One of the best ways to study the immunological ...

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus

One important feature of the major opportunistic human pathogen Staphylococcus aureus is its extraordinary ability to rapidly acquire resistance to antibiotics. Genomic studies reveal that S. aureus carries many virulence and resistance genes located in mobile genetic elements, suggesting that horizontal gene transfer (HGT) plays a critical role in S. aureus evolution. However, a full and detailed description of the methodology used to study HGT in S. aureus is still lacking, especially regarding natural transformation, which has been recently reported in this bacterium. This work describes three protocols that are useful for the in vitro investigation of HGT in S. aureus: conjugation, phage transduction, and natural transformation. To this aim, the cfr gene (chloramphenicol/florfenicol resistance), which confers the Phenicols, Lincosamides, Oxazolidinones, Pleuromutilins, and Streptogramin A (PhLOPSA)-resistance phenotype, was used. Understanding the mechanisms through which S. aureus transfers genetic materials to other strains is essential to comprehending the rapid acquisition of resistance and helps to clarify the modes of dissemination reported in surveillance programs or to further predict the spreading mode in the future.

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus

We describe here three different protocols for the in vitro investigation of conjugation, transduction, and natural transformation in Staphylococcus aureus.

One important feature of the major opportunistic human pathogen Staphylococcus aureus is its extraordinary ability to rapidly acquire resistance to ...

Come to the Light Side: In Vivo Monitoring of Pseudomonas aeruginosa Biofilm Infections in Chronic Wounds in a Diabetic Hairless Murine Model

The presence of bacteria as structured biofilms in chronic wounds, especially in diabetic patients, is thought to prevent wound healing and resolution. Chronic mouse wounds models have been used to understand the underlying interactions between the microorganisms and the host. The models developed to date rely on the use of haired animals and terminal collection of wound tissue for determination of viable bacteria. While significant insight has been gained with these models, this experimental procedure requires a large number of animals and sampling is time consuming. We have developed a novel murine model that incorporates several optimal innovations to evaluate biofilm progression in chronic wounds: a) it utilizes hairless mice, eliminating the need for hair removal; b) applies pre-formed biofilms to the wounds allowing for the immediate evaluation of persistence and effect of these communities on host; c) monitors biofilm progression by quantifying light production by a genetically engineered bioluminescent strain of Pseudomonas aeruginosa, allowing real-time monitoring of the infection thus reducing the number of animals required per study. In this model, a single full-depth wound is produced on the back of STZ-induced diabetic hairless mice and inoculated with biofilms of the P. aeruginosa bioluminescent strain Xen 41. Light output from the wounds is recorded daily in an in vivo imaging system, allowing for in vivo and in situ rapid biofilm visualization and localization of biofilm bacteria within the wounds. This novel method is flexible as it can be used to study other microorganisms, including genetically engineered species and multi-species biofilms, and may be of special value in testing anti-biofilm strategies including antimicrobial occlusive dressings.

Come to the Light Side: In Vivo Monitoring of Pseudomonas aeruginosa Biofilm Infections in Chronic Wounds in a Diabetic Hairless Murine Model

Here we describe a novel diabetic murine model utilizing hairless mice for real-time, non-invasive, monitoring of biofilm wound infections of bioluminescent Pseudomonas aeruginosa. This method can be adapted to evaluate infection of other bacterial species and genetically modified microorganisms, including multi-species biofilms, and test the efficacy of antibiofilm strategies.

The presence of bacteria as structured biofilms in chronic wounds, especially in diabetic patients, is thought to prevent wound healing and resolution. ...

Intraperitoneal Glucose Tolerance Test, Measurement of Lung Function, and Fixation of the Lung to Study the Impact of Obesity and Impaired Metabolism on Pulmonary Outcomes

Obesity and respiratory disorders are major health problems. Obesity is becoming an emerging epidemic with an expected number of over 1 billion obese individuals worldwide by 2030, thus representing a growing socioeconomic burden. Simultaneously, obesity-related comorbidities, including diabetes as well as heart and chronic lung diseases, are continuously on the rise. Although obesity has been associated with increased risk for asthma exacerbations, worsening of respiratory symptoms, and poor control, the functional role of obesity and perturbed metabolism in the pathogenesis of chronic lung disease is often underestimated, and underlying molecular mechanisms remain elusive. This article aims to present methods to assess the effect of obesity on metabolism, as well as lung structure and function. Here, we describe three techniques for mice studies: (1) assessment of intraperitoneal glucose tolerance (ipGTT) to analyze the effect of obesity on glucose metabolism; (2) measurement of airway resistance (Res) and respiratory system compliance (Cdyn) to analyze the effect of obesity on lung function; and (3) preparation and fixation of the lung for subsequent quantitative histological assessment. Obesity-related lung diseases are probably multifactorial, stemming from systemic inflammatory and metabolic dysregulation that potentially adversely influence lung function and the response to therapy. Therefore, a standardized methodology to study molecular mechanisms and the effect of novel treatments is essential.

The incidence of obesity is rising and increases the risk of chronic lung diseases. To establish the underlying mechanisms and preventive strategies, well-defined animal models are needed. Here, we provide three methods (glucose-tolerance-test, body plethysmography, and lung fixation) to study the effect of obesity on pulmonary outcomes in mice.

Obesity and respiratory disorders are major health problems. Obesity is becoming an emerging epidemic with an expected number of over 1 billion obese ...

Arbovirus Infections As Screening Tools for the Identification of Viral Immunomodulators and Host Antiviral Factors

RNA interference- and genome editing-based screening platforms have been widely used to identify host cell factors that restrict virus replication. However, these screens are typically conducted in cells that are naturally permissive to the viral pathogen under study. Therefore, the robust replication of viruses in control conditions may limit the dynamic range of these screens. Furthermore, these screens may be unable to easily identify cellular defense pathways that restrict virus replication if the virus is well-adapted to the host and capable of countering antiviral defenses. In this article, we describe a new paradigm for exploring virus-host interactions through the use of screens that center on naturally abortive infections by arboviruses such as vesicular stomatitis virus (VSV). Despite the ability of VSV to replicate in a wide range of dipteran insect and mammalian hosts, VSV undergoes a post-entry, abortive infection in a variety of cell lines derived from lepidopteran insects, such as the gypsy moth (Lymantria dispar). However, these abortive VSV infections can be &#34;rescued&#34; when host cell antiviral defenses are compromised. We describe how VSV strains encoding convenient reporter genes and restrictive L. dispar cell lines can be paired to set-up screens to identify host factors involved in arbovirus restriction. Furthermore, we also show the utility of these screening tools in the identification of virally encoded factors that rescue VSV replication during coinfection or through ectopic expression, including those encoded by mammalian viruses. The natural restriction of VSV replication in L. dispar cells provides a high signal-to-noise ratio when screening for the conditions that promote VSV rescue, thus enabling the use of simplistic luminescence- and fluorescence-based assays to monitor the changes in VSV replication. These methodologies are valuable for understanding the interplay between host antiviral responses and viral immune evasion factors.

Here, we present the protocols to identify 1) virus-encoded immunomodulators that promote arbovirus replication and 2) eukaryotic host factors that restrict arbovirus replication. These fluorescence- and luminescence-based methods allow researchers to rapidly obtain quantitative readouts of arbovirus replication in simplistic assays with low signal-to-noise ratios.

RNA interference- and genome editing-based screening platforms have been widely used to identify host cell factors that restrict virus replication. ...