Name: design and development of a model to study the effect of supplemental oxygen on the cystic fibrosis airway microbiome
Uploaded: 2021-08-03T14:00:00
Description: Watch this Scientific Journal Video about Design and Development of a Model to Study the Effect of Supplemental Oxygen on the Cystic Fibrosis Airway Microbiome at JoVE.com

Part of this work was performed at the Marine Biological Lab with support from the Marine Biological Lab, DOE (DE-SC0016127), NSF (MCB1822263), HHMI (grant number 5600373), and a gift from the Simons Foundation.

This study received approval from the Partners Institutional Review Board (Protocol # 2018P002934). Inclusion criterion included adult patients with cystic fibrosis who provided written informed consent for the study. There was no exclusion criterion. According to protocol guidelines, all sputum samples were collected from patients with cystic fibrosis during a scheduled outpatient visit with their clinical provider.
1. Artificial Sputum Medium Preparation
NOTE: Quant...

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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=bioBakery:+a+meta'omic+analysis+environment.">bioBakery: a meta'omic analysis environment.</a> Bioinformatics. 34 (7), 1235-1237 (2018).</li><li>Truong, D. 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=MetaPhlAn2+for+enhanced+metagenomic+taxonomic+profiling.">MetaPhlAn2 for enhanced metagenomic taxonomic profiling.</a> Nature Methods. 12 (10), 902-903 (2015).</li><li>Stammler, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adjusting+microbiome+profiles+for+differences+in+microbial+load+by+spike-in+bacteria.">Adjusting microbiome profiles for differences in microbial load by spike-in bacteria.</a> Microbiome. 4 (1), 28 (2016).</li><li>Henke, M. O., Renner, A., Huber, R. M., Seeds, M. C., Rubin, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MUC5AC+and+MUC5B+mucins+are+decreased+in+cystic+fibrosis+airway+secretions.">MUC5AC and MUC5B mucins are decreased in cystic fibrosis airway secretions.</a> American Journal of Respiratory Cell and Molecular Biology. 31 (1), 86-91 (2004).</li><li>Henderson, A. G., 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+airway+secretions+exhibit+mucin+hyper+concentration+and+increased+osmotic+pressure.">Cystic fibrosis airway secretions exhibit mucin hyper concentration and increased osmotic pressure.</a> Journal of Clinical Investigation. 124 (7), 3047-3060 (2014).</li><li>Matthews, L. W., Spector, S., Lemm, J., Potter, J. 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In this study, an in vitro model was developed to study the effect of hyperoxia on lung microbial communities. This model, based on artificial sputum medium and daily sparging of serum bottles, maintains elevated oxygen concentrations and supports the growth of microbes identified in sputum from pwCF.
There are several critical steps of this approach. First is the choice to use filter-sterilization rather than heat-sterilization of the artificial sputum medium. Filter-sterilization pr...

Cystic fibrosis (CF) is a genetic disease characterized by an inability to clear thick mucus from the lungs, leading to repeated infections and progressive lung function decline that often results in the need for lung transplantation or death. The airway microbiome of people with cystic fibrosis (pwCF) appears to track disease activity1, with a reduction in microbial diversity associated with adverse long-term outcomes2,3. In clinical studies of pwCF, supplemental oxygen therapy has been associated with more advanced disease4,5, though traditionally, the use of oxygen therapy has been viewed as simply a marker for disease severity6. Recent studies from a clinical trial of patients with respiratory failure have shown that higher patient oxygen levels are paradoxically associated with an increase in serious bacterial infections and higher mortality7, suggesting that supplemental oxygen may contribute to disease pathogenesis. The effect of supplemental oxygen on the cystic fibrosis lung microbiome and associated lung and airway microbial communities has not been well studied.
Mechanistic studies often cannot be performed directly on human subjects due to logistical difficulties and potential ethical issues associated with interventions of unknown medical benefit or harm. Translational approaches that integrate human biospecimens into model systems can offer important biological insights in these cases. While the ability to use or tolerate oxygen has traditionally been an important component of microbial classification, little is known about how the therapeutic introduction of supplemental oxygen to the environment might perturb airway microbial communities. To shed light on the unknown effects of supplemental oxygen on the airway microbiomes of pwCF, we needed to address two major challenges; first, the creation of a culture medium that physiologically approximates the composition of CF sputum; second, the creation of a model system that allows the maintenance of elevated oxygen concentrations in culture over extended periods of time.
Artificial sputum media (ASM) are widely used to emulate lung sputum ex vivo8,9,10, but there is no clear consensus on a specific recipe. This protocol describes an artificial sputum medium recipe and preparation strategy carefully designed to physiologically approximate sputum from pwCF. Table 1 outlines the chosen recipe values based on published literature. Basic chemical components and pH were matched to values identified by studies of human CF sputum11,12,13. Low concentration physiological nutrients were added using egg yolk, which was included as 0.25% of the final volume10, as well as vitamin and trace metal mixes14,15. Mucin, the key component of sputum16, was included at 1% w/v14. Although more labor-intensive, filter sterilization was chosen over the more conventional practice of heat sterilization to reduce potential problems from heat-induced denaturation of essential media components10. An additional benefit of filter sterilization is that it generates media that are transparent (heat-sterilization can create turbid media due to precipitation and coagulation of salts and proteins), allowing this artificial sputum media to be used to follow microbial growth based on increases in turbidity.
This model system for the hyperoxic culture is based on anaerobic culturing techniques where oxygen is added rather than removed, creating a model for the effect of supplemental oxygen use for pwCF. Figure 1 and the associated oxygen sparging protocol outlines the components of an oxygen sparging system, which can be obtained at low cost from general laboratory and hospital suppliers. This system enables the mixing of compressed oxygen and air to fixed concentrations ranging from 21%-100% oxygen. The integration of an oxygen sensor allows for the verification of the concentration of the output gas mixture, as well as checking the outflow gas composition of previously sparged serum bottles to verify that the oxygen conditions have been maintained within the desired range.
This protocol outlines procedures to create an artificial sputum medium, the construction and use of an oxygen sparging system, and the application of both to culture CF sputum under differential oxygen conditions.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>BME Vitamins (100x) Solution</td>
			<td>MilliporeSigma</td>
			<td>B6891</td>
			<td>Concentrated solution of supplemental vitamins.</td>
		</tr>
		<tr>
			<td>Crimper, 30 mm</td>
			<td>DWK Life Sciences</td>
			<td>224307</td>
			<td>Crimper for attaching aluminum seals to serum bottles.</td>
		</tr>
		<tr>
			<td>D-(+)-Glucose</td>
			<td>MilliporeSigma</td>
			<td>G7021</td>
			<td>Solid glucose powder (dextrorotatory isomer).</td>
		</tr>
		<tr>
			<td>Diaphragm Pump ME 2 NT</td>
			<td>VACUUBRAND</td>
			<td>20730003</td>
			<td>Vacuum pump for vacuum filtration.</td>
		</tr>
		<tr>
			<td>Egg Yolk Emulsion</td>
			<td>HiMedia</td>
			<td>FD045</td>
			<td>Sterile emulsion of 30% egg yolk in saline.</td>
		</tr>
		<tr>
			<td>Ferritin, Cationized from Horse Spleen</td>
			<td>MilliporeSigma</td>
			<td>F7879</td>
			<td>Ferritin (iron-storage protein) solution.</td>
		</tr>
		<tr>
			<td>FIREBOY plus Safety Bunsen Burner</td>
			<td>Integra Biosciences</td>
			<td>144000</td>
			<td>Bunsen burner with user interface and safety features.</td>
		</tr>
		<tr>
			<td>Hydrion pH Paper (1.0&#8211;14.0)</td>
			<td>Micro Essential Laboratory</td>
			<td>94</td>
			<td>pH testing paper for the range of 1.0&#8211;14.0.</td>
		</tr>
		<tr>
			<td>Hydrion pH Paper (4.0&#8211;9.0)</td>
			<td>Micro Essential Laboratory</td>
			<td>55</td>
			<td>pH testing paper for the range of 4.0&#8211;9.0.</td>
		</tr>
		<tr>
			<td>Hydrion pH Paper (6.0&#8211;8.0)</td>
			<td>Micro Essential Laboratory</td>
			<td>345</td>
			<td>pH testing paper for the range of 6.0&#8211;8.0.</td>
		</tr>
		<tr>
			<td>Hypodermic Needle-Pro EDGE Safety Device, 18 G</td>
			<td>Smiths Medical</td>
			<td>401815</td>
			<td>18 G needles with safety caps.</td>
		</tr>
		<tr>
			<td>In-Line Pressure Gauge</td>
			<td>MilliporeSigma</td>
			<td>20469</td>
			<td>Gas pressure gauge for monitoring bottle pressure.</td>
		</tr>
		<tr>
			<td>Innova 42 Incubated Shaker</td>
			<td>Eppendorf</td>
			<td>2231000756</td>
			<td>Combination incubator/orbital shaker.</td>
		</tr>
		<tr>
			<td>Luer-Lok Syringe with Attached Needle</td>
			<td>Becton Dickinson</td>
			<td>309580</td>
			<td>Combination 3 mL syringe and 18 G needle.</td>
		</tr>
		<tr>
			<td>Luer Valve Assortment</td>
			<td>World Precision Instruments</td>
			<td>14011</td>
			<td>Valves for gas flow tubing.</td>
		</tr>
		<tr>
			<td>LSE Orbital Shaker</td>
			<td>ThermoFisher Scientific</td>
			<td>6780-NP</td>
			<td>Orbital shaker to agitate media during filtration.</td>
		</tr>
		<tr>
			<td>Magnesium Sulfate Heptahydrate</td>
			<td>MilliporeSigma</td>
			<td>M2773</td>
			<td>Solid epsom salt (magnesium sulfate heptahydrate).</td>
		</tr>
		<tr>
			<td>Medical Air Single Stage Regulator with Flowmeter</td>
			<td>Western Enterprises</td>
			<td>M1-346-15FM</td>
			<td>Air flow rate regulator with 15 L/min meter.</td>
		</tr>
		<tr>
			<td>MEM Amino Acids (50x) Solution</td>
			<td>MilliporeSigma</td>
			<td>M5550</td>
			<td>Concentrated solution of essential amino acids.</td>
		</tr>
		<tr>
			<td>MEM Non-Essential Amino Acids (100x) Solution</td>
			<td>MilliporeSigma</td>
			<td>M7145</td>
			<td>Concentrated solution of non-essential amino acids.</td>
		</tr>
		<tr>
			<td>Millex-GP Filter, 0.22 &#181;m</td>
			<td>MilliporeSigma</td>
			<td>SLMP25SS</td>
			<td>0.22 &#181;m polyethersulfone membrane sterile syringe filter.</td>
		</tr>
		<tr>
			<td>Milli-Q Academic</td>
			<td>MilliporeSigma</td>
			<td>ZMQS60E01</td>
			<td>Milli-Q sterile water filtration system.</td>
		</tr>
		<tr>
			<td>MiniOX 3000 Oxygen Monitor</td>
			<td>MSA</td>
			<td>814365</td>
			<td>Gas flow oxygen percentage monitor.</td>
		</tr>
		<tr>
			<td>MOPS Buffer (1 M, pH 9.0)</td>
			<td>Boston BioProducts</td>
			<td>BBM-90</td>
			<td>MOPS buffer for adjusting media pH.</td>
		</tr>
		<tr>
			<td>Mucin from Porcine Stomach</td>
			<td>MilliporeSigma</td>
			<td>M2378</td>
			<td>Mucin (glycosylated gel-forming protein) powder.</td>
		</tr>
		<tr>
			<td>Natural Polypropylene Barbed Fitting Kit</td>
			<td>Harvard Apparatus</td>
			<td>72-1413</td>
			<td>Connectors for gas flow tubing.</td>
		</tr>
		<tr>
			<td>Nextera XT DNA Library Preparation Kit</td>
			<td>Illumina</td>
			<td>FC-131-1096</td>
			<td>Library preparation for identification during sequencing.</td>
		</tr>
		<tr>
			<td>NovaSeq 6000 Sequencing System</td>
			<td>Illumina</td>
			<td>770-2016-025-N</td>
			<td>Shotgun sequencing platform for generating sample reads.</td>
		</tr>
		<tr>
			<td>Oxygen Single Stage Regulator with Flowmeter</td>
			<td>Western Enterprises</td>
			<td>M1-540-15FM</td>
			<td>Oxygen flow rate regulator with 15 L/min meter.</td>
		</tr>
		<tr>
			<td>Oxygen Tubing with 2 Standard Connectors</td>
			<td>SunMed</td>
			<td>2001-01</td>
			<td>Tubing for connecting gas system components.</td>
		</tr>
		<tr>
			<td>Phosphate buffered saline, 10x, pH 7.4</td>
			<td>Molecular Biologicals International</td>
			<td>MRGF-6235</td>
			<td>Concentrated phosphate-buffered saline solution.</td>
		</tr>
		<tr>
			<td>PC 420 Hot Plate/Stirrer</td>
			<td>Marshall Scientific</td>
			<td>CO-PC420</td>
			<td>Combination hot plate/stirrer.</td>
		</tr>
		<tr>
			<td>Potassium Chloride</td>
			<td>MilliporeSigma</td>
			<td>P9541</td>
			<td>Solid potassium chloride salt.</td>
		</tr>
		<tr>
			<td>PTFE Disposable Stir Bars</td>
			<td>ThermoFisher Scientific</td>
			<td>14-513-95</td>
			<td>Disposable magnetic stir bars.</td>
		</tr>
		<tr>
			<td>PTFE Thread Seal Teflon Tape</td>
			<td>VWR</td>
			<td>470042-938</td>
			<td>Teflon tape for reinforcing gas system connections.</td>
		</tr>
		<tr>
			<td>Q-Gard 2 Purification Cartridge</td>
			<td>MilliporeSigma</td>
			<td>QGARD00D2</td>
			<td>Purification cartridge for Milli-Q system.</td>
		</tr>
		<tr>
			<td>Reusable Media Storage Bottles</td>
			<td>ThermoFisher Scientific</td>
			<td>06-423A</td>
			<td>Bottles for mixing and storing culture media.</td>
		</tr>
		<tr>
			<td>Rubber Stopper, 30 mm, Gray Bromobutyl</td>
			<td>DWK Life Sciences</td>
			<td>224100-331</td>
			<td>Rubber stoppers for serum bottles.</td>
		</tr>
		<tr>
			<td>Serum Bottle with Molded Graduations, 500 mL</td>
			<td>DWK Life Sciences</td>
			<td>223952</td>
			<td>Glass serum bottles for sealed culturing.</td>
		</tr>
		<tr>
			<td>Small Bore Extension Set</td>
			<td>Braun Medical</td>
			<td>471960</td>
			<td>Tubing extension with luer lock connectors.</td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td>MilliporeSigma</td>
			<td>S3014</td>
			<td>Solid sodium chloride salt.</td>
		</tr>
		<tr>
			<td>Spike-in Control I (High Microbial Load)</td>
			<td>ZymoBIOMICS</td>
			<td>D6320</td>
			<td>Spike-in microbes (I. halotolerans and A. halotolerans) for absolute microbial load calculations</td>
		</tr>
		<tr>
			<td>Stericup Quick Release Sterile Vacuum Filtration System</td>
			<td>MilliporeSigma</td>
			<td>S2GPU02RE</td>
			<td>250 mL 0.22 &#181;m vacuum filtration chamber.</td>
		</tr>
		<tr>
			<td>Super Sani-Cloth Germicidal Disposable Wipes</td>
			<td>Professional Disposables International</td>
			<td>H04082</td>
			<td>Disposable germicidal wipes for sterilization.</td>
		</tr>
		<tr>
			<td>Trace Metals Mixture, 1000x</td>
			<td>ThermoFisher Scientific</td>
			<td>NC0112668</td>
			<td>Concentrated solution of physiological trace metals.</td>
		</tr>
		<tr>
			<td>Unlined Aluminum Seal, 30 mm</td>
			<td>DWK Life Sciences</td>
			<td>224187-01</td>
			<td>Aluminum seals crimped over top of rubber stoppers.</td>
		</tr>
		<tr>
			<td>USP Medical Grade Air Tank</td>
			<td>Airgas</td>
			<td>AI USP200</td>
			<td>Compressed air tank for input to sparging system.</td>
		</tr>
		<tr>
			<td>USP Medical Grade Oxygen Tank</td>
			<td>Airgas</td>
			<td>OX USP200</td>
			<td>Compressed oxygen tank for input to sparging system.</td>
		</tr>
	</tbody>
</table>

design and development of a model to study the effect of supplemental oxygen on the cystic fibrosis airway microbiome

Airway microbial communities are thought to play an important role in the progression of cystic fibrosis (CF) and other chronic pulmonary diseases. Microbes have traditionally been classified based on their ability to use or tolerate oxygen. Supplemental oxygen is a common medical therapy administered to people with cystic fibrosis (pwCF); however, existing studies on oxygen and the airway microbiome have focused on how hypoxia (low oxygen) rather than hyperoxia (high oxygen) affects the predominantly aerobic and facultative anaerobic lung microbial communities. To address this critical knowledge gap, this protocol was developed using an artificial sputum medium that mimics the composition of sputum from pwCF. The use of filter sterilization, which yields a transparent medium, allows optical methods to follow the growth of single-celled microbes in suspension cultures. To create hyperoxic conditions, this model system takes advantage of established anaerobic culturing techniques to study hyperoxic conditions; instead of removing oxygen, oxygen is added to cultures by daily sparging of serum bottles with a mixture of compressed oxygen and air. Sputum from 50 pwCF underwent daily sparging for a 72-h period to verify the ability of this model to maintain differential oxygen conditions. Shotgun metagenomic sequencing was performed on cultured and uncultured sputum samples from 11 pwCF to verify the ability of this medium to support the growth of commensal and pathogenic microbes commonly found in cystic fibrosis sputum. Growth curves were obtained from 112 isolates obtained from pwCF to verify the ability of this artificial sputum medium to support the growth of common cystic fibrosis pathogens. We find that this model can culture a wide variety of pathogens and commensals in CF sputum, recovers a community highly similar to uncultured sputum under normoxic conditions, and creates different culture phenotypes under varying oxygen conditions. This new approach might lead to a better understanding of unanticipated effects induced by the use of oxygen in pwCF on airway microbial communities and common respiratory pathogens.

These protocols were applied to 50 expectorated sputum samples from pwCF presenting for routine care to an outpatient cystic fibrosis clinic at Massachusetts General Hospital in Boston, Massachusetts. Each patient&#39;s sputum was cultured under 21%, 50%, and 100% oxygen conditions using the artificial sputum medium, with 0.5 mL aliquots taken from each culture at 24 h, 48 h, and 72 h of culture time for testing. Cultures were photographed when extractions were made to track visual changes. In addition, a 0.5 mL aliquot ...

Watch this Scientific Journal Video about Design and Development of a Model to Study the Effect of Supplemental Oxygen on the Cystic Fibrosis Airway Microbiome at JoVE.com

Design and Development of a Model to Study the Effect of Supplemental Oxygen on the Cystic Fibrosis Airway Microbiome

The goal of this protocol is to develop a model system for the effect of hyperoxia on cystic fibrosis airway microbial communities. Artificial sputum medium emulates the composition of sputum, and hyperoxic culture conditions model the effects of supplemental oxygen on lung microbial communities.

Airway microbial communities are thought to play an important role in the progression of cystic fibrosis (CF) and other chronic pulmonary diseases. ...

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