Name: visualizing the effects of sputum on biofilm development using a chambered coverglass model
Uploaded: 2016-12-14T14:00:00
Description: Watch this Scientific Journal Video about Visualizing the Effects of Sputum on Biofilm Development Using a Chambered Coverglass Model at JoVE.com

TB acknowledges a research fellowship from Cystic Fibrosis Canada.

Note that Research Ethics Board (REB) is required to collect and store sputum samples from human subjects. These studies were approved by the Hospital for Sick Children REB#1000019444.
1. Preparing CF Sputum Samples
<ol>
	<li>Collect sputum sample from patients during routine visits to the cystic fibrosis clinic and keep on ice.</li>
	<li>Transport sputum sample on ice within the first hour of collection, to the research laboratory, to undergo processing.</li>
</ol>
2. ...

<ol>
	<li>Beaudoin, T., Waters, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Infections+with+biofilm+formation:+selection+of+antimicrobials+and+role+of+prolonged+antibiotic+therapy.">Infections with biofilm formation: selection of antimicrobials and role of prolonged antibiotic therapy.</a> Pediatr.Infect.Dis.J. , (2016).</li><li>Donlan, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilms:+microbial+life+on+surfaces.">Biofilms: microbial life on surfaces.</a> Emerg.Infect.Dis. 8 (9), 881-890 (2002).</li><li>Hobley, L., Harkins, C., MacPhee, C. E., Stanley-Wall, N. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Giving+structure+to+the+biofilm+matrix:+an+overview+of+individual+strategies+and+emerging+common+themes.">Giving structure to the biofilm matrix: an overview of individual strategies and emerging common themes.</a> FEMS Microbiol.Rev. 39 (5), 649-669 (2015).</li><li>Katharios-Lanwermeyer, S., Xi, C., Jakubovics, N. S., Rickard, A. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mini-review:+Microbial+coaggregation:+ubiquity+and+implications+for+biofilm+development.">Mini-review: Microbial coaggregation: ubiquity and implications for biofilm development.</a> Biofouling. 30 (10), 1235-1251 (2014).</li><li>Donlan, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilm+formation:+a+clinically+relevant+microbiological+process.">Biofilm formation: a clinically relevant microbiological process.</a> Clin.Infect.Dis. 33 (8), 1387-1392 (2001).</li><li>Bjarnsholt, 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=The+in+vivo+biofilm.">The in vivo biofilm.</a> Trends Microbiol. 21 (9), 466-474 (2013).</li><li>Mah, T. F., Pitts, B., Pellock, B., Walker, G. C., Stewart, P. S., O'Toole, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+genetic+basis+for+Pseudomonas+aeruginosa+biofilm+antibiotic+resistance.">A genetic basis for Pseudomonas aeruginosa biofilm antibiotic resistance.</a> Nature. 426 (6964), 306-310 (2003).</li><li>Mah, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilm-specific+antibiotic+resistance.">Biofilm-specific antibiotic resistance.</a> Future Microbiol. 7 (9), 1061-1072 (2012).</li><li>Beaudoin, T., Zhang, L., Hinz, A. J., Parr, C. J., Mah, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+biofilm-specific+antibiotic+resistance+gene+ndvB+is+important+for+expression+of+ethanol+oxidation+genes+in+Pseudomonas+aeruginosa+biofilms.">The biofilm-specific antibiotic resistance gene ndvB is important for expression of ethanol oxidation genes in Pseudomonas aeruginosa biofilms.</a> J. Bacteriol. 194 (12), 3128-3136 (2012).</li><li>Beaudoin, T., Aaron, S. D., Giesbrecht-Lewis, T., Vandemheen, K., Mah, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+clonal+strains+of+Pseudomonas+aeruginosa+isolated+from+cystic+fibrosis+patients+in+Ontario,+Canada.">Characterization of clonal strains of Pseudomonas aeruginosa isolated from cystic fibrosis patients in Ontario, Canada.</a> Can. J. Microbiol. 56 (7), 548-557 (2010).</li><li>Vidya, 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=Chronic+infection+phenotypes+of+Pseudomonas+aeruginosa+are+associated+with+failure+of+eradication+in+children+with+cystic+fibrosis.">Chronic infection phenotypes of Pseudomonas aeruginosa are associated with failure of eradication in children with cystic fibrosis.</a> Eur.J.Clin.Microbiol.Infect.Dis. , (2015).</li><li>Beaudoin, T., Lafayette, S., Nguyen, D., Rousseau, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mucoid+Pseudomonas+aeruginosa+caused+by+mucA+mutations+result+in+activation+of+TLR2+in+addition+to+TLR5+in+airway+epithelial+cells.">Mucoid Pseudomonas aeruginosa caused by mucA mutations result in activation of TLR2 in addition to TLR5 in airway epithelial cells.</a> Biochem.Biophys.Res.Commun. 428 (1), 150-154 (2012).</li><li>Beaudoin, 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=The+level+of+p38alpha+mitogen-activated+protein+kinase+activation+in+airway+epithelial+cells+determines+the+onset+of+innate+immune+responses+to+planktonic+and+biofilm+Pseudomonas+aeruginosa.">The level of p38alpha mitogen-activated protein kinase activation in airway epithelial cells determines the onset of innate immune responses to planktonic and biofilm Pseudomonas aeruginosa.</a> J.Infect.Dis. 207 (10), 1544-1555 (2013).</li><li>LaFayette, S. 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=Cystic+fibrosis-adapted+quorum+sensing+mutants+cause+hyperinflammatory+responses.">Cystic fibrosis-adapted quorum sensing mutants cause hyperinflammatory responses.</a> Sci.Adv. 1 (6), e1500199 (2015).</li><li>Staudinger, B. 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=Conditions+associated+with+the+cystic+fibrosis+defect+promote+chronic+Pseudomonas+aeruginosa+infection.">Conditions associated with the cystic fibrosis defect promote chronic Pseudomonas aeruginosa infection.</a> Am.J.Respir.Crit.Care Med. 189 (7), 812-824 (2014).</li><li>Kennedy, 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=Activity+of+Tobramycin+against+Cystic+Fibrosis+Isolates+of+Burkholderia+cepacia+Complex+Grown+as+Biofilms.">Activity of Tobramycin against Cystic Fibrosis Isolates of Burkholderia cepacia Complex Grown as Biofilms.</a> Antimicrob.Agents Chemother. 60 (1), 348-355 (2015).</li><li>Tom, S. K., Yau, Y. C., Beaudoin, T., LiPuma, J. J., Waters, V. <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+High-Dose+Antimicrobials+on+Biofilm+Growth+of+Achromobacter+Species+Isolated+from+Cystic+Fibrosis+Patients.">Effect of High-Dose Antimicrobials on Biofilm Growth of Achromobacter Species Isolated from Cystic Fibrosis Patients.</a> Antimicrob.Agents Chemother. 60 (1), 650-652 (2015).</li><li>Heydorn, 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=Quantification+of+biofilm+structures+by+the+novel+computer+program+COMSTAT.">Quantification of biofilm structures by the novel computer program COMSTAT.</a> Microbiology. 146 (Pt 10), 2395-2407 (2000).</li><li>Vorregaard, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Informatics and Mathematical Modelling. , (2008).</li><li>Jurcisek, J. A., Dickson, A. C., Bruggeman, M. E., Bakaletz, L. O. <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+Biofilm+Formation+in+an+8-well+Chamber+Slide.">In vitro Biofilm Formation in an 8-well Chamber Slide.</a> J. Vis. Exp. (47), e2481 (2011).</li></ol>

The methods described herein allow for visualization of bacterial biofilms grown in the presence of exogenous products. Not surprisingly, the production of the exoproducts is of importance when using this type of system. For instance, Dithiothreitol (DTT), is often used on human sputum samples to help liquefy the samples. However, the effect of DTT alone can decrease biofilm development and viability (data not shown). Thus, proper controls for all conditions are necessary. Furthermore, the addition of human sputum produc...

Bacterial biofilms are groups of microorganisms that are attached to one another and encased in a self-secreted matrix.1,2 Classically, they represent bacteria physically attached to an abiotic or biotic surface formed under conditions of flow. Biofilms have also been shown to grow in static conditions (absence of flow) and distal from surfaces, such as at the air-liquid interface of thermal pools or pellicles formed in test tubes. These biofilms have long been recognized in the environment and are a major detriment to industrial processes, as they can form in water reservoirs or in pipes, resulting in biofouling, corrosion and blockages.3,4
Biofilms are also critical in healthcare settings, as they have been shown be involved in catheter related infections, pulmonary infections in cystic fibrosis patients, as well as in numerous other infections.5,6 One of the hallmarks of biofilm infections is the decreased susceptibility of bacteria to antibiotics and impaired clearance by the innate immune system.7-9 The most well studied, clinically relevant scenarios involving biofilm-based infection occurs in patients with cystic fibrosis (CF), who are chronically infected with Pseudomonas aeruginosa biofilms. P. aeruginosa can undergo a number of changes during establishment of chronic infection that make it very difficult to treat.10,11 Biofilms can differentially activate innate immunity and drive inflammation.12-14 As these infections lead to increased morbidity and mortality in CF patients, it is crucial to understand factors that can affect biofilm development in this context.
A recent study suggests that host-factors are critical in the formation of P. aeruginosa biofilm aggregates.15 These biofilms contribute to reduced susceptibility to antibiotics and host defense mechanisms. The presence of host-derived factors, such as neutrophil elastase, as well as secreted products from microorganisms present in the CF lung, have the potential to greatly modulate biofilm formation and development.16 Additionally, biofilms interact with the host to modulate expression of numerous pathways and initiate inflammation. While high throughput methods, such as the standard crystal violet assay, can provide some information with regards to the biofilm process, visualization of the biofilm in response to these factors provide more in-depth information.
In this manuscript we describe a method for using factors from the sputum of patients with CF to study the development of biofilms in vitro. This method allows for rapid visualization of biofilms exposed to sputum containing host factors using a commercial biofilm viability kit. This technique can be used to visually identify changes that occur during biofilm growth in the presence of exogenous products, and represents an improved method to analyze the changes in biofilm development under various conditions.

<table border="0" cellpadding="0" cellspacing="0" width="1270">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Lab-Tek II Chambered coverglass, #1.5 borosilicate, 8-well</td>
			<td style="width:159px;">Thermo Sicher Scientific</td>
			<td style="width:136px;">155409</td>
			<td style="width:729px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Filmtracer Live/Dead Biofilm Viabilty Kit</td>
			<td style="width:159px;">Thermo Fisher Scientific</td>
			<td style="width:136px;">L10316</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Blood agar plates</td>
			<td style="width:159px;">Thermo Fisher Scientific</td>
			<td style="width:136px;">R10215</td>
			<td>Confirming viability via CFU counts or selecting colonies for innoculation</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">COMSTAT</td>
			<td style="width:159px;">Availble software online</td>
			<td style="width:136px;"></td>
			<td>COMSTAT is software to analyze biofilm images. Available www.comstat.dk&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Millers LB Broth</td>
			<td style="width:159px;">Thermo Fisher Scientific</td>
			<td>12780-052</td>
			<td style="width:729px;">Standard media for overnight gowth/biofilm growth</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Millex-GV Syringe Filters</td>
			<td style="width:159px;">Millipore</td>
			<td>SLGV013SL</td>
			<td>Filtering of sputum supernants</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Phosphate Buffered Saline (Dulbecco A)</td>
			<td style="width:159px;">Oxoid</td>
			<td style="width:136px;">BR0014G</td>
			<td>Washing of biofilm chambers after media removal</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Zeiss AxioVert 200M</td>
			<td style="width:159px;">Carl Zeiss</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Hamamatsu C9100-13 EM-CCD</td>
			<td style="width:159px;">QS Technologies Inc.</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Spectral Borealis</td>
			<td style="width:159px;">Qs Technologies Inc.</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Perkin Elmer Volocity</td>
			<td style="width:159px;">QS Technologies Inc.</td>
			<td style="width:136px;"></td>
			<td>Instructions for this software can be found at: http://cellularimaging.perkinelmer.com/pdfs/manuals/VolocityuserGuide.pdf</td>
		</tr>
	</tbody>
</table>

visualizing the effects of sputum on biofilm development using a chambered coverglass model

Biofilms consist of groups of bacteria encased in a self-secreted matrix. They play an important role in industrial contamination as well as in the development and persistence of many health related infections. One of the most well described and studied biofilms in human disease occurs in chronic pulmonary infection of cystic fibrosis patients. When studying biofilms in the context of the host, many factors can impact biofilm formation and development. In order to identify how host factors may affect biofilm formation and development, we used a static chambered coverglass method to grow biofilms in the presence of host-derived factors in the form of sputum supernatants. Bacteria are seeded into chambers and exposed to sputum filtrates. Following 48 hr of growth, biofilms are stained with a commercial biofilm viability kit prior to confocal microscopy and analysis. Following image acquisition, biofilm properties can be assessed using different software platforms. This method allows us to visualize key properties of biofilm growth in presence of different substances including antibiotics.

The overall design of the experiment is represented in Figure 1. The use of this protocol provides a convenient method to visualize the changes in biofilms grown for different periods of time (e.g., 24, 48 or 72 hr). Importantly, exogenous signals, such as sputum filtrates, can be added to visualize the changes in biofilm development. As seen in Figure 2, the presence of 10% sputum filtrates can change the architecture of the biofilm (Fig...

Watch this Scientific Journal Video about Visualizing the Effects of Sputum on Biofilm Development Using a Chambered Coverglass Model at JoVE.com

Visualizing the Effects of Sputum on Biofilm Development Using a Chambered Coverglass Model

This protocol describes the visualization of biofilm development following exposure to host-factors using a slide chamber model. This model allows for direct visualization of biofilm development as well as analysis of biofilm parameters using computer software programs.

Biofilms consist of groups of bacteria encased in a self-secreted matrix. They play an important role in industrial contamination as well as in the ...

The overall goal of this procedure is to visualize and quantify changes to biofilms in response to sputum and antibiotics. This method can be used by researchers to understand key questions, such as how the efficacy of various antibiotics against bacterial biofilms can be impacted by the presence of sputum. The main advantage of this methodology is it allows individuals to see changes occurring in biofilms in response to different factors.To begin the experiment, record the volume of the previously obtained sputum sample. Add phosphate-buffered saline, or PBS, add two times the volume of the sample. Next, use a transfer pipette to thoroughly mix the sample.Vortex the sample on the highest setting for one minute to mix it completely. Aliquot one milliliter of the mixture into 1.5 milliliter microcentrifuge tubes. Then spin down the tubes.Following centrifugation, save the supernatant and discard the pellet. Filter sterilize the supernatant through a 0.22 micron filter and collect it in a clean microcentrifuge tube. Store the sputum supernatant at 80 degrees Celsius for future use.Place 40 microliters of previously prepared culture into four milliliters of fresh Luria broth, or LB media, and grow the bacteria to obtain a culture with an optical density of 0.55 at 600 nanometers. Next, dilute 100 microliters of 0.5 OD culture into 400 microliters of prepared 10%sputum filtrates in LB.Use 200 microliters of the dilution to seed the wells of the slide chambers. Allow the bacteria to attach for four hours at 37 degrees Celsius without shaking.After four hours, remove the media and gently wash the biofilm with 1X fresh LB.Replace the remaining media with 200 microliters of fresh LB.Allow the biofilms to grow at 37 degrees Celsius without shaking. Replace the media every 12 hours without washing until the biofilm is ready for microscopy. It's very important to gently wash the slides so as not to disrupt any attached bacteria.Following growth, remove the media from the chamber wells and gently wash each chamber two times with 300 microliters of sterile PBS. Next, to prepare the biofilm staining mixture, add one microliter of each dye provided in the viability kit to each milliliter of solution needed and mix the solution. The optimal amount of dye and staining time is determined empirically for each organism.Add 200 microliters of the staining mixture to each well of the chambered cover glass. Incubate the cover glass. After incubation, remove the staining mixture from the chambers and wash each well with 300 microliters of sterile PBS.Replace the PBS with fresh media. Finally, proceed with visualization via confocal microscopy. Representative images of Burkholderia cepacia complex, or BCC clinical isolates, following 48 hours of growth in chambered cover glass with media alone or in the presence of 10%sputum filtrates demonstrate that their presence can change the architecture of the biofilm.The images were analyzed with Comstat software to obtain key biofilm parameters, including the average thickness of the biofilm, which was increased when treated with 10%sputum. In order to appreciate the different factors'effects on biofilm growth, clinical isolates were grown in media only or with sputum and either was treated with or without antibiotic. After watching this video, you should have a good understanding of how to form and treat biofilms on chambered cover glass and prepare them for staining and confocal analysis.

visualizing-effects-sputum-on-biofilm-development-using-chambered

Research

JoVE Journal

Immunology and Infection

In vitro Biofilm Formation in an 8-well Chamber Slide

The chronic nature of many diseases is attributed to the formation of bacterial biofilms which are recalcitrant to traditional antibiotic therapy. Biofilms are community-associated bacteria attached to a surface and encased in a matrix. The role of the extracellular matrix is multifaceted, including facilitating nutrient acquisition, and offers significant protection against environmental stresses (e.g. host immune responses). In an effort to acquire a better understanding as to how the bacteria within a biofilm respond to environmental stresses we have used a protocol wherein we visualize bacterial biofilms which have formed in an 8-well chamber slide. The biofilms were stained with the BacLight Live/Dead stain and examined using a confocal microscope to characterize the relative biofilm size, and structure under varying incubation conditions. Z-stack images were collected via confocal microscopy and analyzed by COMSTAT. This protocol can be used to help elucidate the mechanism and kinetics by which biofilms form, as well as identify components that are important to biofilm structure and stability.

In vitro Biofilm Formation in an 8-well Chamber Slide

This article describes the procedure for the formation and visualization of a bacterial biofilm grown within an 8-well chamber slide

The chronic nature of many diseases is attributed to the formation of bacterial biofilms which are recalcitrant to traditional antibiotic therapy. ...

A Microplate Assay to Assess Chemical Effects on RBL-2H3 Mast Cell Degranulation: Effects of Triclosan without Use of an Organic Solvent

Mast cells play important roles in allergic disease and immune defense against parasites. Once activated (e.g. by an allergen), they degranulate, a process that results in the exocytosis of allergic mediators. Modulation of mast cell degranulation by drugs and toxicants may have positive or adverse effects on human health. Mast cell function has been dissected in detail with the use of rat basophilic leukemia mast cells (RBL-2H3), a widely accepted model of human mucosal mast cells3-5. Mast cell granule component and the allergic mediator &#946;-hexosaminidase, which is released linearly in tandem with histamine from mast cells6, can easily and reliably be measured through reaction with a fluorogenic substrate, yielding measurable fluorescence intensity in a microplate assay that is amenable to high-throughput studies1. Originally published by Naal et al.1, we have adapted this degranulation assay for the screening of drugs and toxicants and demonstrate its use here.
Triclosan is a broad-spectrum antibacterial agent that is present in many consumer products and has been found to be a therapeutic aid in human allergic skin disease7-11, although the mechanism for this effect is unknown. Here we demonstrate an assay for the effect of triclosan on mast cell degranulation. We recently showed that triclosan strongly affects mast cell function2. In an effort to avoid use of an organic solvent, triclosan is dissolved directly into aqueous buffer with heat and stirring, and resultant concentration is confirmed using UV-Vis spectrophotometry (using &#949;280 = 4,200 L/M/cm)12. This protocol has the potential to be used with a variety of chemicals to determine their effects on mast cell degranulation, and more broadly, their allergic potential.

Mast cell degranulation, the release of allergic mediators, is important in allergy, asthma, and parasite defense. Here we demonstrate techniques1 for assessing effects of drugs and toxicants on degranulation, methodology recently utilized to exhibit the powerful inhibitory effect of antibacterial agent triclosan2.

Mast cells play important roles in allergic disease and immune defense against parasites. Once activated (e.g. by an allergen), they degranulate, a ...

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

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

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

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

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a prerequisite for pneumococcal infections such as pneumonia and otitis media. In vitro adherence assays can be used to study the attachment of pneumococci to epithelial cell monolayers and to investigate potential interventions, such as the use of probiotics, to inhibit pneumococcal&#160;colonization.&#160;The protocol described here is used to investigate the effects of the probiotic Streptococcus salivarius on the adherence of pneumococci to the human epithelial cell line CCL-23 (sometimes referred to as HEp-2 cells). The assay involves three main steps: 1) preparation of epithelial and bacterial cells, 2) addition of bacteria to epithelial cell monolayers, and 3) detection of adherent pneumococci by viable counts (serial dilution and plating) or quantitative real-time PCR (qPCR). This technique is relatively straightforward and does not require specialized equipment other than a tissue culture setup. The assay can be used to test other probiotic species and/or potential inhibitors of pneumococcal colonization and can be easily modified to address other scientific questions regarding pneumococcal adherence and invasion.

Investigating the Effects of Probiotics on Pneumococcal Colonization Using an In Vitro Adherence Assay

In vitro adherence assays can be used to study the attachment of Streptococcus pneumoniae to epithelial cell monolayers and to investigate potential interventions such as the use of probiotics for inhibiting pneumococcal colonization.

Adherence of Streptococcus pneumoniae (the pneumococcus) to the epithelial lining of the nasopharynx can result in colonization and is considered a ...

Analyzing the Effects of Stromal Cells on the Recruitment of Leukocytes from Flow

Stromal cells regulate the recruitment of circulating leukocytes during inflammation through cross-talk with neighboring endothelial cells. Here we describe two in vitro &#8220;vascular&#8221; models for studying the recruitment of circulating neutrophils from flow by inflamed endothelial cells. A major advantage of these models is the ability to analyze each step in the leukocyte adhesion cascade in order, as would occur in vivo. We also describe how both models can be adapted to study the role of stromal cells, in this case mesenchymal stem cells (MSC), in regulating leukocyte recruitment.
Primary endothelial cells were cultured alone or together with human MSC in direct contact on Ibidi microslides or on opposite sides of a Transwell filter for 24 hr. Cultures were stimulated with tumor necrosis factor alpha (TNF&#945;) for 4 hr and incorporated into a flow-based adhesion assay. A bolus of neutrophils was perfused over the endothelium for 4 min. The capture of flowing neutrophils and their interactions with the endothelium was visualized by phase-contrast microscopy.
In both models, cytokine-stimulation increased endothelial recruitment of flowing neutrophils in a dose-dependent manner. Analysis of the behavior of recruited neutrophils showed a dose-dependent decrease in rolling and a dose-dependent increase in transmigration through the endothelium. In co-culture, MSC suppressed neutrophil adhesion to TNF&#945;-stimulated endothelium.
Our flow based-adhesion models mimic the initial phases of leukocyte recruitment from the circulation. In addition to leukocytes, they can be used to examine the recruitment of other cell types, such as therapeutically administered MSC or circulating tumor cells. Our multi-layered co-culture models have shown that MSC communicate with endothelium to modify their response to pro-inflammatory cytokines, altering the recruitment of neutrophils. Further research using such models is required to fully understand how stromal cells from different tissues and conditions (inflammatory disorders or cancer) influence the recruitment of leukocytes during inflammation.

The ability of inflamed endothelium to recruit leukocytes from flow is regulated by mesenchymal stromal cells. We describe two in vitro models incorporating primary human cells that can be used to assess neutrophil recruitment from flow and examine the role that mesenchymal stromal cells play in regulating this process.

Stromal cells regulate the recruitment of circulating leukocytes during inflammation through cross-talk with neighboring endothelial cells. Here we ...

Flow Cytometric Analysis of Particle-bound Bet v 1 Allergen in PM10

Flow cytometry is a method widely used to quantify suspended solids such as cells or bacteria in a size range from 0.5 to several tens of micrometers in diameter. In addition to a characterization of forward and sideward scatter properties, it enables the use of fluorescent labeled markers like antibodies to detect respective structures. Using indirect antibody staining, flow cytometry is employed here to quantify birch pollen allergen (precisely Bet v 1)-loaded particles of 0.5 to 10 &#181;m in diameter in inhalable particulate matter (PM10, particle size &#8804;10 &#181;m in diameter). PM10 particles may act as carriers of adsorbed allergens possibly transporting them to the lower respiratory tract, where they could trigger allergic reactions.
So far the allergen content of PM10 has been studied by means of enzyme linked immunosorbent assays (ELISAs) and scanning electron microscopy. ELISA measures the dissolved and not the particle-bound allergen. Compared to scanning electron microscopy, which can visualize allergen-loaded particles, flow cytometry may additionally quantify them. As allergen content of ambient air can deviate from birch pollen count, allergic symptoms might perhaps correlate better with allergen exposure than with pollen count. In conjunction with clinical data, the presented method offers the opportunity to test in future experiments whether allergic reactions to birch pollen antigens are associated with the Bet v 1 allergen content of PM10 particles &#62;0.5 &#181;m.

Here, we present a protocol to quantify allergen-loaded particles by flow cytometry. Ambient particulate matter particles may act as carriers of adsorbed allergens. We show here that flow cytometry, a method widely used to characterize suspended solids &#62;0.5 &#181;m in diameter, can be used to measure these allergen-loaded particles.

Flow cytometry is a method widely used to quantify suspended solids such as cells or bacteria in a size range from 0.5 to several tens of micrometers in ...

Real-time Imaging and Quantification of Fungal Biofilm Development Using a Two-Phase Recirculating Flow System

In oropharyngeal candidiasis, members of the genus Candida must adhere to and grow on the oral mucosal surface while under the effects of salivary flow. While models for the growth under flow have been developed, many of these systems are expensive, or do not allow imaging while the cells are under flow. We have developed a novel apparatus that allows us to image the growth and development of Candida albicans cells under flow and in real-time. Here, we detail the protocol for the assembly and use of this flow apparatus, as well as the quantification of data that are generated. We are able to quantify the rates that the cells attach to and detach from the slide, as well as to determine a measure of the biomass on the slide over time. This system is both economical and versatile, working with many types of light microscopes, including inexpensive benchtop microscopes, and is capable of extended imaging times compared to other flow systems. Overall, this is a low-throughput system that can provide highly detailed real-time information on the biofilm growth of fungal species under flow.

We describe the assembly, operation, and cleaning of a flow apparatus designed to image fungal biofilm formation in real time while under flow. We also provide and discuss quantitative algorithms to be used on the acquired images.

In oropharyngeal candidiasis, members of the genus Candida must adhere to and grow on the oral mucosal surface while under the effects of salivary flow. ...

An In Vitro Batch-culture Model to Estimate the Effects of Interventional Regimens on Human Fecal Microbiota

The emerging role of the gut microbiome in several human diseases demands a breakthrough of new tools, techniques and technologies. Such improvements are needed to decipher the utilization of microbiome modulators for human health benefits. However, the large-scale screening and optimization of modulators to validate microbiome modulation and predict related health benefits may be practically difficult due to the need for large number of animals and/or human subjects. To this end, in vitro or ex vivo models can facilitate preliminary screening of microbiome modulators. Herein, it is optimized and demonstrated an ex vivo fecal microbiota culture system that can be used for examining the effects of various interventions of gut microbiome modulators including probiotics, prebiotics and other food ingredients, aside from nutraceuticals and drugs, on the diversity and composition of the human gut microbiota. Inulin, one of the most widely studied prebiotic compounds and microbiome modulators, is used as an example here to examine its effect on the healthy fecal microbiota composition and its metabolic activities, such as fecal pH and the fecal levels of organic acids including lactate and short-chain fatty acids (SCFAs). The protocol may be useful for studies aimed at estimating the effects of different interventions of modulators on fecal microbiota profiles and at predicting their health impacts.

This protocol describes an in vitro batch-culture fermentation system of human fecal microbiota, using inulin (a well-known prebiotic and one of the most widely studied microbiota modulators) to demonstrate the use of this system in estimating effects of specific interventions on fecal microbiota composition and metabolic activities.

The emerging role of the gut microbiome in several human diseases demands a breakthrough of new tools, techniques and technologies. Such improvements are ...

High-throughput Screening of Chemical Compounds to Elucidate Their Effects on Bacterial Persistence

Bacterial persisters are defined as a small subpopulation of phenotypic variants with the capability of tolerating high concentrations of antibiotics. They are an important health concern as they have been associated with recurrent chronic infections. Although stochastic and deterministic dynamics of stress-related mechanisms are known to play a significant role in persistence, mechanisms underlying the phenotypic switch to/from the persistence state are not completely understood. While persistence factors triggered by environmental signals (e.g., depletion of carbon, nitrogen and oxygen sources) have been extensively studied, the impacts of osmolytes on persistence are yet to be determined. Using microarrays (i.e., 96 well plates containing various chemicals), we have designed an approach to elucidate the effects of various osmolytes on Escherichia coli persistence in a high throughput manner. This approach is transformative as it can be readily adapted for other screening arrays, such as drug panels and gene knockout libraries.

In this method paper, we present a high-throughput screening strategy to identify chemical compounds, such as osmolytes, that have a significant impact on bacterial persistence.

Bacterial persisters are defined as a small subpopulation of phenotypic variants with the capability of tolerating high concentrations of antibiotics. ...

Quantifying the Effects of Antimicrobials on In vitro Biofilm Architecture using COMSTAT Software

Biofilms are aggregates of microorganisms that rely on a self-produced matrix of extracellular polymeric substance for protection and structural integrity. The nosocomial pathogen, Pseudomonas aeruginosa, is known to adopt a biofilm mode of growth, causing chronic pulmonary infection in patients with cystic fibrosis (CF). The computer program, COMSTAT, is a useful tool for quantifying antimicrobial-induced changes in P. aeruginosa biofilm architecture by extracting data from three-dimensional confocal images. However, standardized operation of the software is less commonly addressed, which is important for optimal reporting of biofilm behavior and cross-center comparison. Thus, the aim of this protocol is to provide a simple and reproducible framework for quantifying in vitro biofilm structures under varying antimicrobial conditions via COMSTAT. The technique is modeled using a CF P. aeruginosa isolate, grown in the form of biofilm replicates, and exposed to tobramycin and the anti-Psl monoclonal antibody, Psl0096. The step-by-step approach aims to reduce user ambiguity and minimize the chance of overlooking crucial image-processing steps. Specifically, the protocol emphasizes the elimination of subjective variations associated with the manual operation of COMSTAT, including image segmentation and the selection of appropriate quantitative analysis functions. Although this method requires users to spend additional time processing confocal images prior to running COMSTAT, it helps minimize misrepresented biofilm heterogenicity in automated outputs.

Quantifying the Effects of Antimicrobials on In vitro Biofilm Architecture using COMSTAT Software

Antimicrobial-induced changes to Pseudomonas aeruginosa biofilm architecture differ among clinical isolates cultured from patients with cystic fibrosis and chronic pulmonary infection. Following confocal microscopy, COMSTAT software can be utilized to quantify variations in biofilm architecture (e.g., surface area, thickness, biomass) for individual isolates to assess the efficacy of anti-infective agents.