We express our gratitude to the children and families of the COPSAC2010 cohort study for all their support and commitment. We acknowledge and appreciate the unique efforts of the COPSAC research team and the technical help from Technician Lisbeth Buus Rosholm, Technical University of Denmark, for the measurement of cytokines and chemokines.

The studies were conducted in accordance with the guiding principles of the Declaration of Helsinki. Approvals from the Ethics Committee for Copenhagen (KF 01-289/96 for COPSAC2000 and H-B-2008-093 for COPSAC2010) and the Danish Data Protection Agency were obtained, and written informed consent was obtained from both parents of each subject before enrollment.
1. Experimental Setup
<ol>
	<li>Use sheets of filter paper (fibrous hydroxylated-polyester sheets, see the Table of Materials)6,7.
	<ol>
		<li>Cut out strips 3&#160;x 15 mm in size for a 1-month-old child and in an L-shape for older children and adults (5&#160;x 20&#160;x 10 mm (short arm of the L)).</li>
	</ol>
	</li>
	<li>Insert one piece of filter paper into each nostril of an infant using forceps. Place the filter paper at the anterior part of the inferior turbinate (approximately 1 cm inside the nostril for neonates and 1.5 cm for all other ages).
	<ol>
		<li>Place neonates on a bed and give them sugar water for comfort. 
		NOTE: For children of all other ages, the sampling is performed most easily with the subject seated on a chair.</li>
		<li>For older children, insert the long arm of the L-shaped filter paper into each nostril.</li>
	</ol>
	</li>
	<li>Apply a nose clip around the nostrils to minimize discomfort and to avoid the accidental loss of the filter paper.</li>
	<li>Remove the filter papers after 2 min of absorption.</li>
	<li>Place the filter papers in labeled tubes and freeze them immediately at -80 &#176;C.</li>
	<li>Make a note of any symptoms of airway infection shown by the child on the day of sampling.</li>
	<li>Record any sneezing, persistent crying, or epistaxis that occurs during the 2 min of sampling.</li>
</ol>
2. Quantification of Airway Immune-mediators
<ol>
	<li>Take up to 10 random samples from the freezer. Record the identification numbers. Keep the samples on ice during the whole working process.</li>
	<li>After thawing on ice, immerse the filter papers (per subject) from both nostrils in 300 &#181;L of freshly prepared buffer (see the Table of Materials) containing one complete protease inhibitor tablet (see the Table of Materials) per 25 mL of buffer.
	<ol>
		<li>Adjust the volume of buffer as per the size of the filter paper.
		<ol>
			<li>Use 300 &#181;L of buffer for filter papers 3&#160;x 15 mm in size.</li>
			<li>If only one filter paper is available, use half the buffer volume (150 &#181;L).</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Transfer the samples to a plate shaker (400 rpm) for 5 min. Use a timer.</li>
	<li>Transfer the moist filter papers and assay buffer into the cup of a cellulose acetate tube filter (0.22 &#181;m pore size) placed within a microcentrifuge tube (see the Table of Materials).</li>
	<li>Centrifuge at 16,000 x g for 5 min in a cooled centrifuge (at 4 &#176;C) to obtain filtered nasal extract in the tube.</li>
	<li>Remove the cup and keep the tubes on ice while aliquoting the nasal extract into the wells of low-protein binding storage plates (see the Table of Materials).</li>
	<li>Store at -80 &#176;C until analysis.</li>
	<li>Determine the concentrations of cytokines and chemokines in the nasal extracts using a high-sensitivity, electrochemiluminesce-based multiplexed array system (see the Table of Materials). 
	NOTE: A human 10-plex TH1/TH2 cytokine assay, 9-plex chemokine assay, and single-plex IL-17A, TGF-&#946;1, and TSLP were performed here.
	<ol>
		<li>For the assays, incubate the nasal extracts overnight at 4 &#176;C. Conduct the measurements as per the standard manufacturer protocol (see the Table of Materials). 
		NOTE: The immunoassays (see the Table of Materials) typically have a high dynamic range for measurement ranging between 1 &#38; 10,000 pg/mL, but for some assays, it can be 100,000 pg/mL. This means that all samples can be run at the same dilution, thus limiting the influence of dissimilar dilutions in healthy and diseased subjects, as is the case in other similar immunoassays. The lower limit of detection for all cytokines was 1 pg/mL or less, and for chemokines, it ranged between 1 &#38; 50 pg/mL. TSLP was not detectable in 98% of samples at 1 month of age.</li>
	</ol>
	</li>
</ol>
3. Statistics
<ol>
	<li>Log-transform the data prior to analysis to obtain normally distributed residuals of the cytokine and chemokine levels.</li>
	<li>If the samples are analyzed in more than one batch, correct the cytokine and chemokine data for batch-wise centering on the log-transformed data.
	<ol>
		<li>Incorporate the overall mean and anti-log transformation to obtain data in the original measurement units. 
		NOTE: For every set of analyses done, consider adjusting variables that affect the level of cytokines and chemokines. This could be maternal influences (e.g., alcohol consumption and smoking during pregnancy), breastfeeding, adverse events during sampling, siblings, pets in the home, etc.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Bousquet, J., van Cauwenberge, P., Khaltaev, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Allergic+Rhinitis+and+Its+Impact+on+Asthma.">Allergic Rhinitis and Its Impact on Asthma.</a> J Allergy Clin Immunol. 108 (5), 147-334 (2001).</li><li>Howarth, P. H., Persson, C. G. A., Meltzer, E. O., Jacobson, M. R., Durham, S. R., Silkoff, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Objective+monitoring+of+nasal+airway+inflammation+in+rhinitis.">Objective monitoring of nasal airway inflammation in rhinitis.</a> J Allergy Clin Immunol. 115 (3), 414-441 (2005).</li><li>Bensch, G. W., Nelson, H. S., Borish, L. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+cytokines+in+nasal+secretions+after+nasal+antigen+challenge:+lack+of+influence+of+antihistamines.">Evaluation of cytokines in nasal secretions after nasal antigen challenge: lack of influence of antihistamines.</a> Ann Allergy Asthma Immunol. 88 (5), 457-462 (2002).</li><li>Sussman, G. L., Mason, J., Compton, D., Stewart, J., Ricard, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+efficacy+and+safety+of+fexofenadine+HCl+and+pseudoephedrine,+alone+and+in+combination,+in+seasonal+allergic+rhinitis.">The efficacy and safety of fexofenadine HCl and pseudoephedrine, alone and in combination, in seasonal allergic rhinitis.</a> J Allergy Clin Immunol. 104 (1), 100-106 (1999).</li><li>Bisgaard, H., Robinson, C., R&#248;meling, F., Mygind, N., Church, M., Holgate, S. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Leukotriene+C4+and+histamine+in+early+allergic+reaction+in+the+nose.">Leukotriene C4 and histamine in early allergic reaction in the nose.</a> Allergy. 43 (3), 219-227 (1988).</li><li>Chawes, B. L. K., 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+novel+method+for+assessing+unchallenged+levels+of+mediators+in+nasal+epithelial+lining+fluid.">A novel method for assessing unchallenged levels of mediators in nasal epithelial lining fluid.</a> J Allergy Clin Immunol. 125 (6), 1387-1389 (2010).</li><li>F&#0248;lsgaard, N. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathogenic+bacteria+colonizing+the+airways+in+asymptomatic+neonates+stimulates+topical+inflammatory+mediator+release.">Pathogenic bacteria colonizing the airways in asymptomatic neonates stimulates topical inflammatory mediator release.</a> Am J Respir Crit Care Med. 187 (6), 589-595 (2013).</li><li>F&#0248;lsgaard, N. V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neonatal+Cytokine+Profile+in+the+Airway+Mucosal+Lining+Fluid+Is+Skewed+by+Maternal+Atopy.">Neonatal Cytokine Profile in the Airway Mucosal Lining Fluid Is Skewed by Maternal Atopy.</a> Am J Respir Crit Care Med. 185 (3), 275-280 (2012).</li><li>Chawes, B. 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=Effect+of+Vitamin+D3+Supplementation+During+Pregnancy+on+Risk+of+Persistent+Wheeze+in+the+Offspring:+A+Randomized+Clinical+Trial.">Effect of Vitamin D3 Supplementation During Pregnancy on Risk of Persistent Wheeze in the Offspring: A Randomized Clinical Trial.</a> JAMA. 315 (4), 353-361 (2016).</li><li>Bischoff, A. 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=Altered+Response+to+A(H1N1)pnd09+Vaccination+in+Pregnant+Women:+A+Single+Blinded+Randomized+Controlled+Trial.">Altered Response to A(H1N1)pnd09 Vaccination in Pregnant Women: A Single Blinded Randomized Controlled Trial.</a> PloS One. 8 (4), 56700 (2013).</li><li>Wolsk, H. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Picornavirus-Induced+Airway+Mucosa+Immune+Profile+in+Asymptomatic+Neonates.">Picornavirus-Induced Airway Mucosa Immune Profile in Asymptomatic Neonates.</a> J Infect Dis. 213 (8), 1262-1270 (2016).</li><li>Wolsk, H. M., Chawes, B. L., F&#248;lsgaard, N. V., Rasmussen, M. A., Brix, S., Bisgaard, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Siblings+Promote+a+Type+1/Type+17-oriented+immune+response+in+the+airways+of+asymptomatic+neonates.">Siblings Promote a Type 1/Type 17-oriented immune response in the airways of asymptomatic neonates.</a> Allergy. 71 (6), 820-828 (2016).</li><li>Alam, R., Sim, T. C., Hilsmeier, K., Grant, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+new+technique+for+recovery+of+cytokines+from+inflammatory+sites+in+situ.">Development of a new technique for recovery of cytokines from inflammatory sites in situ.</a> J Immunol Methods. 155 (1), 25-29 (1992).</li><li>Ishizaka, 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=New+bronchoscopic+microsample+probe+to+measure+the+biochemical+constituents+in+epithelial+lining+fluid+of+patients+with+acute+respiratory+distress+syndrome.">New bronchoscopic microsample probe to measure the biochemical constituents in epithelial lining fluid of patients with acute respiratory distress syndrome.</a> Crit Care Med. 29 (4), 896-898 (2001).</li><li>Ishizaka, 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=Elevation+of+KL-6,+a+lung+epithelial+cell+marker,+in+plasma+and+epithelial+lining+fluid+in+acute+respiratory+distress+syndrome.">Elevation of KL-6, a lung epithelial cell marker, in plasma and epithelial lining fluid in acute respiratory distress syndrome.</a> Am J Physiol Lung Cell Mol Physiol. 286 (6), 1088-1094 (2004).</li><li>Nakano, Y., 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=Endothelin-1+level+in+epithelial+lining+fluid+of+patients+with+acute+respiratory+distress+syndrome.">Endothelin-1 level in epithelial lining fluid of patients with acute respiratory distress syndrome.</a> Respirology. 12 (5), 740-743 (2007).</li><li>Komaki, Y., 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=Cytokine-mediated+xanthine+oxidase+upregulation+in+chronic+obstructive+pulmonary+disease's+airways.">Cytokine-mediated xanthine oxidase upregulation in chronic obstructive pulmonary disease's airways.</a> Pulm Pharmacol Ther. 18 (4), 297-302 (2005).</li><li>Moeller, A., Franklin, P., Hall, G. L., Horak, F., Wildhaber, J. H., Stick, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+exhaled+breath+condensates+in+infants.">Measuring exhaled breath condensates in infants.</a> Pediatr Pulmonol. 41 (2), 184-187 (2006).</li></ol>

All authors declare no potential, perceived, or real conflict of interest regarding the content of this manuscript. The funding agencies did not have any role in the design and conduct of the study; the collection, management, and interpretation of the data; or the preparation, review, and approval of the manuscript. No pharmaceutical company was involved in the study.

With the technique presented here, we were able to determine the in vivo upper-airway mucosal immune profile in children from as early as 1 month of age, which has not been done previously. We observed that presence of specific airway bacteria and picornaviruses7,11, as well as other pre&#160;and perinatal exposures, were mirrored in the airway immune profile of the neonates. Furthermore, we used these airway immune profile data to study the mechanism of...

The mucosal lining fluid of the nose makes up the liquid part of the upper-airway system. It consists of a complex matrix of mediators derived from the interplay between the epithelium and the immune cells that make up the first line of defense against invading microorganisms. The nasal mucosa is easily accessible, and there is a strong functional and immunological relationship between the nose and the bronchi1. This compartment is of special interest in relation to airway diseases that are common in childhood, such as asthma and allergic rhinitis, but also to a range of other respiratory disorders more prevalent later in life.
Here, we describe the implementation of a method to sample undisturbed mucosal lining fluid from the nasal cavity using a filter paper-based, noninvasive technique, as well as a subsequent extraction procedure, used to elute protein-based analytes from the filter papers prior to their quantification. This technique can, for example, be used to obtain in vivo immune signatures of both healthy individuals and individuals with various respiratory diseases. Furthermore, it is possible to examine exposures of importance for a specific immune signature and to evaluate if it is a predictor or mediator of later disease development.
Mucosal lining fluid has previously been obtained by nasal lavage2, which is often preceded by a nasal challenge test, where an allergen is introduced in high levels to stimulate an inflammatory response3,4. However, the nasal lavage technique is not feasible in young children and introduces an unknown dilution factor, which confounds the outcomes, as the diluted mediator levels can fall below the detection limit of the assay5. Moreover, due to the unknown dilution factor, the measured analyte responses from the nasal challenge tests are not comparable between individuals, thereby limiting the usefulness of the nasal lavage technique in a cohort setting. Finally, allergen challenge is only applicable in sensitized subjects, and other challenges, such as the histamine challenge, are not physiologically relevant, potentially causing a ceiling effect on mediator release. These problems are circumvented in the presented filter paper-based technique for mucosal lining fluid collection, where the individual secretion of fluids and analyte levels are the only factors that influence inter-individual variance.
During the extraction procedure, analytes are eluted from the filter papers after the addition of identical volumes of buffer to all samples. This favors similar ex vivo dilution of all samples. An extraction buffer of albumin-based isotonic salt solution is used for the extraction step; it enables the extraction of protein-based mediators and stabilizes proteins to limit denaturation during the subsequent freezing of eluted proteins prior to quantification. To avoid protein degradation during the extraction phase, a cocktail of protease inhibitors is added to the extraction buffer.
The implementation of techniques that allow for the quantification of undisturbed, in vivo-generated immune mediators at mucosal sites is of the utmost importance. First, the mucosal site makes up the largest immunological organ in the body. Second, the nasal location is the primary site of airborne exposure and is tightly connected to the respiratory immunological compartment of the lungs1. Third, the possibility of surveying this important organ with a noninvasive technique opens the possibility to provide a plethora of information on the important microbe-immune interaction axis in relation to health and disease in the airways. Fourth, there are many other possible applications of this technique, such as studying local immunological alterations in randomized, controlled trials of drugs and micronutrients.
We initially implemented the technique in the Copenhagen Prospective Studies on Asthma in Childhood2000 (COPSAC2000) cohort, where we determined the immune profile of the mucosal lining fluid in 7-year-old children with allergic rhinitis versus healthy controls13. Subsequently, we successfully applied this technique to the longitudinal COPSAC2010 cohort and assessed airway immune profiles at 1 month, 2 years, and 6 years of age and at instances of acute respiratory symptoms. Results from the 1-month-old neonates have demonstrated important associations between the immune signature and early-life environmental exposure7,8,9,10,11,12.

<table><tbody><tr><td>Fibrous hydroxylatedpolyester sheets</td><td>Accuwik Ultra&amp;nbsp;</td><td>SPR0730</td><td>Filter paper</td></tr><tr><td>Milliplex Assay Buffer&amp;nbsp;</td><td>Millipore</td><td>L-AB</td><td>Buffer</td></tr><tr><td>Low-protein binding storage plates&amp;nbsp;</td><td>Thermo Scientific</td><td>CLS8161</td><td>Plates</td></tr><tr><td>Protease Inhibitor</td><td>Roche</td><td>11873580001</td><td>complete EDTA-free Protease Inhibitor Cocktail</td></tr><tr><td>Reader of multi-spot plates</td><td>Mesoscale</td><td>NA</td><td>Sector imager 6000</td></tr><tr><td>Assays&amp;nbsp;</td><td>Mesoscale</td><td></td><td>Human 10-plex TH1/TH2 cytokine assay and 9-plex chemokine assay, and singleplex IL-17A, TGF-&amp;beta;1and TSLP. A description can be found online on www.mesoscale.com</td></tr></tbody></table>

noninvasive sampling of mucosal lining fluid for the quantification of in vivo upper airway immune-mediator levels

This protocol describes noninvasive sampling of undisturbed upper airway mucosal lining fluid. It also details the extraction procedure used prior to the analysis of immune mediators in fluid eluates for the study of the airway topical immune signature, without the need for stimulation procedures (often used by other techniques). The mucosal lining fluid is sampled on a strip of filter paper placed at the anterior part of the inferior turbinate and left for 2 min of absorption. Analytes are eluted from the filter papers, and the extracted protein-based eluates are analyzed by an electrochemiluminescence-based immunoassay, allowing for the high-sensitivity quantification of low- and high-level analytes in the same sample. We measured the in vivo levels of 20 preselected immune mediators related to specific immune signaling pathways in the upper airway mucosa, but the technique is not limited to that specific panel or sampling site. The technique was first implemented in 7-year-old children from the Copenhagen Prospective Studies on Asthma in Childhood2000 (COPSAC2000) cohort with allergic rhinitis. It was thereafter used in the longitudinal COPSAC2010 birth cohort, sampled at 1 month, 2 years, and 6 years of age and at instances of acute respiratory symptoms. We successfully obtained and analyzed samples from 620 (89%) of 700 1-month-old children; a few samples were below the assay detection limit (reported as the median (Inter-Quartile Range (IQR)). The number of samples below the detection limit (i.e.&#160;from 0 to the set point for the lower limit of detection) for each mediator was 29 (7.25 - 119.5). This technique enables the quantification of the in vivo airway mucosal immune profile from birth, can be applied longitudinally, and can be applied to studies on the effect of genetics and early-life environmental exposures, pathophysiology, endotyping, and monitoring of respiratory diseases, and development and evaluation of novel therapeutics.

Baseline Characteristics of the Airway Immune Profiles: 
Complete data on upper airway mucosal immune mediator levels at 1 month of age was obtained in 620 (89%) of the 700 children enrolled in the COPSAC2010 cohort. Ten neonates were enrolled before the technique was established, and 19 did not attend the 1-month visit. Additionally, 47 samples were excluded because they were extracted and measured in another laboratory used in a pilot study, and 4 sample...

Watch this Scientific Journal Video about Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels at JoVE.com

Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels

This protocol describes a noninvasive technique for the sampling of undisturbed mucosal lining fluid from the upper airways. It can be used to perform the quantification of in vivo levels of protein mediators, such as cytokines and chemokines, in subjects of all ages.

Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels

This protocol describes noninvasive sampling of undisturbed upper airway mucosal lining fluid. It also details the extraction procedure used prior to the ...

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Immunology and Infection

Unit 1

Upper Respiratory Tract Infections

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10.3K Views.  University of Copenhagen. Dit protocol beschrijft een noninvasive techniek voor de bemonstering van ongestoord mucosal voering vloeistof uit de bovenste luchtwegen. Het kan worden gebruikt voor het uitvoeren van de kwantificering van in vivo niveaus van proteïne bemiddelaars, zoals cytokines en chemokines, bij patiënten van alle leeftijden.

Video: Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels

Murine Model of Allergen Induced Asthma

Asthma is a major cause of morbidity and mortality, affecting some 300 million people throughout the world.1 More than 8% of the US population has asthma, with the prevalence increasing.2 As with other diseases, animal models of allergic airway disease greatly facilitate understanding of the underlying pathophysiology, help identify potential therapeutic targets, and allow preclinical testing of possible new therapies. Models of allergic airway disease have been developed in several animal species, but murine models are particularly attractive due to the low cost, ready availability, and well-characterized immune systems of these animals.3 Availability of a variety of transgenic strains further increases the attractiveness of these models.4 Here we describe two murine models of allergic airway disease, both employing ovalbumin as the antigen. Following initial sensitization by intraperitoneal injection, one model delivers the antigen challenge by nebulization, the other by intratracheal delivery. These two models offer complementary advantages, with each mimicking the major features of human asthma.5
The major features of acute asthma include an exaggerated airway response to stimuli such as methacholine (airway hyperresponsiveness; AHR) and eosinophil-rich airway inflammation. These are also prominent effects of allergen challenge in our murine models,5,6 and we describe techniques for measuring them and thus evaluating the effects of experimental manipulation. Specifically, we describe both invasive7 and non-invasive8 techniques for measuring airway hyperresponsiveness as well as methods for assessing infiltration of inflammatory cells into the airways and the lung. Airway inflammatory cells are collected by bronchoalveolar lavage while lung histopathology is used to assess markers of inflammation throughout the organ. These techniques provide powerful tools for studying asthma in ways that would not be possible in humans.

Experimental mouse models of allergic asthma offer new possibilities for studying disease pathogenesis and developing new therapeutics. These models are well suited to measuring factors governing the allergic immune response, airway inflammation, and pulmonary pathophysiology.

Asthma is a major cause of morbidity and mortality, affecting some 300 million people throughout the world.1 More than 8% of the US population has asthma, ...

Real-Time, Semi-Automated Fluorescent Measurement of the Airway Surface Liquid pH of Primary Human Airway Epithelial Cells

In recent years, the importance of mucosal surface pH in the airways has been highlighted by its ability to regulate airway surface liquid (ASL) hydration, mucus viscosity and activity of antimicrobial peptides, key parameters involved in innate defense of the lungs. This is of primary relevance in the field of chronic respiratory diseases such as cystic fibrosis (CF) where these parameters are dysregulated. While different groups have studied ASL pH both in vivo and in vitro, their methods report a relatively wide range of ASL pH values and even contradictory findings regarding any pH differences between non-CF and CF cells. Furthermore, their protocols do not always provide enough details in order to ensure reproducibility, most are low throughput and require expensive equipment or specialized knowledge to implement, making them difficult to establish in most labs. Here we describe a semi-automated fluorescent plate reader assay that enables the real-time measurement of ASL pH under thin film conditions that more closely resemble the in vivo situation. This technique allows for stable measurements for many hours from multiple airway cultures simultaneously and, importantly, dynamic changes in ASL pH in response to agonists and inhibitors can be monitored. To achieve this, the ASL of fully differentiated primary human airway epithelial cells (hAECs) are stained overnight with a pH-sensitive dye in order to allow for the reabsorption of the excess fluid to ensure thin film conditions. After fluorescence is monitored in the presence or absence of agonists, pH calibration is performed in situ to correct for volume and dye concentration. The method described provides the required controls to make stable and reproducible ASL pH measurements, which ultimately could be used as a drug discovery platform for personalized medicine, as well as adapted to other epithelial tissues and experimental conditions, such as inflammatory and/or host-pathogen models.

We present a protocol to make dynamic measurements of the airway surface liquid pH under thin film conditions using a plate-reader.

In recent years, the importance of mucosal surface pH in the airways has been highlighted by its ability to regulate airway surface liquid (ASL) ...

Biochemistry

A Reversible, Non-invasive Method for Airway Resistance Measurements and Bronchoalveolar Lavage Fluid Sampling in Mice

Airway hyperreactivity (AHR) measurements and bronchoalveolar lavage (BAL) fluid sampling are essential to experimental asthma models, but repeated procedures to obtain such measurements in the same animal are generally not feasible.  Here, we demonstrate protocols for obtaining from mice repeated measurements of AHR and bronchoalveolar lavage fluid samples.  Mice were challenged intranasally seven times over 14 days with a potent allergen or sham treated.  Prior to the initial challenge, and within 24 hours following each intranasal challenge, the same animals were anesthetized, orally intubated and mechanically ventilated.  AHR, assessed by comparing dose response curves of respiratory system resistance (RRS) induced by increasing intravenous doses of acetylcholine (Ach) chloride between sham and allergen-challenged animals, were determined.  Afterwards, and via the same intubation, the left lung was lavaged so that differential enumeration of airway cells could be performed.  These studies reveal that repeated measurements of AHR and BAL fluid collection are possible from the same animals and that maximal airway hyperresponsiveness and airway eosinophilia are achieved within 7-10 days of initiating allergen challenge.  This novel technique significantly reduces the number of mice required for longitudinal experimentation and is applicable to diverse rodent species, disease models and airway physiology instruments.  

Repeated measurements of rodent respiratory physiology and sampling of airway inflammatory cells are desirable, but generally not feasible. Here we describe a repeatable method for orally intubating mice that permits repeated measurements of airway hyperreactivity and sampling of airway inflammatory cells.

Airway hyperreactivity (AHR) measurements and bronchoalveolar lavage (BAL) fluid sampling are essential to experimental asthma models, but repeated ...

Biology

Human Lung Dendritic Cells: Spatial Distribution and Phenotypic Identification in Endobronchial Biopsies Using Immunohistochemistry and Flow Cytometry

The lungs are constantly exposed to the external environment, which in addition to harmless particles, also contains pathogens, allergens, and toxins. In order to maintain tolerance or to induce an immune response, the immune system must appropriately handle inhaled antigens. Lung dendritic cells (DCs) are essential in maintaining a delicate balance to initiate immunity when required without causing collateral damage to the lungs due to an exaggerated inflammatory response. While there is a detailed understanding of the phenotype and function of immune cells such as DCs in human blood, the knowledge of these cells in less accessible tissues, such as the lungs, is much more limited, since studies of human lung tissue samples, especially from healthy individuals, are scarce. This work presents a strategy to generate detailed spatial and phenotypic characterization of lung tissue resident DCs in healthy humans that undergo a bronchoscopy for the sampling of endobronchial biopsies. Several small biopsies can be collected from each individual and can be subsequently embedded for ultrafine sectioning or enzymatically digested for advanced flow cytometric analysis. The outlined protocols have been optimized to yield maximum information from small tissue samples that, under steady-state conditions, contain only a low frequency of DCs. While the present work focuses on DCs, the methods described can directly be expanded to include other (immune) cells of interest found in mucosal lung tissue. Furthermore, the protocols are also directly applicable to samples obtained from patients suffering from pulmonary diseases where bronchoscopy is part of establishing the diagnosis, such as chronic obstructive pulmonary disease (COPD), sarcoidosis, or lung cancer.

Lung-resident immune cells, including dendritic cells (DCs) in humans, are critical for defense against inhaled pathogens and allergens. However, due to the scarcity of human lung tissue, studies are limited. This work presents protocols to process human mucosal endobronchial biopsies for studying lung DCs using immunohistochemistry and flow cytometry.

The lungs are constantly exposed to the external environment, which in addition to harmless particles, also contains pathogens, allergens, and toxins. In ...

Bronchoalveolar Lavage of Murine Lungs to Analyze Inflammatory Cell Infiltration

Bronchoalveolar Lavage (BAL) is an experimental procedure that is used to examine the cellular and acellular content of the lung lumen ex vivo to gain insight into an ongoing disease state.
Here, a simple and efficient method is described to perform BAL on murine lungs without the need of special tools or equipment. BAL fluid is isolated by inserting a catheter in the trachea of terminally anesthetized mice, through which a saline solution is instilled into the bronchioles. The instilled fluid is gently retracted to maximize BAL fluid retrieval and to minimize shearing forces. This technique allows the viability, function, and structure of cells within the airways and BAL fluid to be preserved.
Numerous techniques may be applied to gain further understanding of the disease state of the lung. Here, a commonly used technique for the identification and enumeration of different types of immune cells is described, where&#160;flow cytometry is combined with a select panel of fluorescently labeled cell surface-specific markers. The BAL procedure presented here can also be used to analyze infectious agents, fluid constituents, or inhaled particles within murine lungs.

The health status of the lung is reflected by the type and number of immune cells that are present in the bronchioles of the lung. We describe a bronchoalveolar lavage technique that allows the isolation and study of nonadherent cells and soluble factors from the lower respiratory tract of mice.

Bronchoalveolar Lavage (BAL) is an experimental procedure that is used to examine the cellular and acellular content of the lung lumen ex vivo to gain ...

Label-free Neutrophil Enrichment from Patient-derived Airway Secretion Using Closed-loop Inertial Microfluidics

Airway secretions contain a large number of immune-related cells, e.g., neutrophils, macrophages, and lymphocytes, which can be used as a major resource to evaluate a variety of pulmonary diseases, both for research and clinical purposes. However, due to the heterogeneous and viscous nature of patient mucus, there is currently no reliable dissociation method that does not damage the host immune cells in the patient airway secretion. In this research, we introduce a sample preparation method that uses inertial microfluidics for the patient&#39;s immune assessment. Regardless of the heterogeneous fluidic properties of the clinical samples, the proposed method recovers more than 95% of neutrophils from airway secretion samples that are diluted 1,000-fold with milliliters of clean saline. By recirculating the concentrated output stream to the initial sample reservoir, a high concentration, recovery, and purity of the immune cells are provided; recirculation is considered a trade-off to the single-run syringe-based operation of inertial microfluidics. The closed-loop operation of spiral microfluidics provides leukocytes without physical or chemical disturbance, as demonstrated by the phorbol 12-myristate 13-acetate (PMA)-induced elastase release of sorted neutrophils.

In this research, we demonstrate a label-free neutrophil separation method from clinical airway secretions using closed-loop operation of spiral inertial microfluidics. The proposed method would expand the clinical in vitro assays for various respiratory diseases.

Airway secretions contain a large number of immune-related cells, e.g., neutrophils, macrophages, and lymphocytes, which can be used as a major resource ...

Absorption of Nasal and Bronchial Fluids: Precision Sampling of the Human Respiratory Mucosa and Laboratory Processing of Samples

The methods of nasal absorption (NA) and bronchial absorption (BA) use synthetic absorptive matrices (SAM) to absorb the mucosal lining fluid (MLF) of the human respiratory tract. NA is a non-invasive technique which absorbs fluid from the inferior turbinate, and causes minimal discomfort. NA has yielded reproducible results with the ability to frequently repeat sampling of the upper airway. 
By comparison, alternative methods of sampling the respiratory mucosa, such as nasopharyngeal aspiration (NPA) and conventional swabbing, are more invasive and may result in greater data variability. Other methods have limitations, for instance, biopsies and bronchial procedures are invasive, sputum contains many dead and dying cells and requires liquefaction, exhaled breath condensate (EBC) contains water and saliva, and lavage samples are dilute and variable.
BA can be performed through the working channel of a bronchoscope in clinic. Sampling is well tolerated and can be conducted at multiple sites in the airway. BA results in MLF samples being less dilute than bronchoalveolar lavage (BAL) samples.
This article demonstrates the techniques of NA and BA, as well as the laboratory processing of the resulting samples, which can be tailored to the desired downstream biomarker being measured. These absorption techniques are useful alternatives to the conventional sampling techniques used in clinical respiratory research.

This manuscript describes the use of nasal and bronchial absorption techniques, specifically using synthetic absorptive matrices (SAM) to sample the mucosal lining fluid (MLF) of the upper and lower airway. These methods provide better standardization and tolerability than existing respiratory sampling techniques.

The methods of nasal absorption (NA) and bronchial absorption (BA) use synthetic absorptive matrices (SAM) to absorb the mucosal lining fluid (MLF) of the ...

Medicine

Methodology for Sputum Induction and Laboratory Processing

The technique of sputum induction and processing is a recognized non-invasive method allowing the collection and analysis of cells from the airways, which is interesting in various respiratory diseases like asthma, chronic obstructive pulmonary disease (COPD), chronic cough, or idiopathic pulmonary fibrosis. This technique is well tolerated, safe and non-invasive, but is currently limited to research services and specialized centers in clinical practice because it is technically demanding, time-consuming, and requires trained staff. The success rate of sputum induction and analysis is about 80%.
Here, we describe the induction and laboratory processing of sputum samples. Sputum is induced by inhalation of hypertonic or isotonic saline with salbutamol. For the processing, we use the whole sputum technique. Dithiothreitol (DTT) is used to allow mucolysis of sputum samples. The primary aim of sputum processing is to obtain a differential cell count to study the cell types present in the airway lumen. Additional analyses may also be performed on sputum supernatant and sputum cells, which may allow further investigation into inflammatory processes and immune mechanisms. Examples include studying mediators in sputum supernatant and performing a large spectrum of analysis on sputum cells such as flow cytometry, genomics, or proteomics.
Finally, representative results of sputum analysis in healthy controls, asthmatics, and COPD patients are presented.

Here we describe the technique of sputum induction. This protocol also explains the sputum processing to perform a differential cell count and to collect sputum supernatant and cells for further analysis.

The technique of sputum induction and processing is a recognized non-invasive method allowing the collection and analysis of cells from the airways, which ...

Assessing Respiratory Immune Responses to Haemophilus Influenzae

Haemophilus influenzae (Hi) is a prevalent bacterium found in a range of respiratory conditions. A variety of different assays/techniques may be used to assess the respiratory immune/inflammatory response to this bacterium. Flow cytometry and confocal microscopy are fluorescence-based technologies that allow detailed characterization of biological responses.&#160;Different forms of Hi antigen can be used, including cell wall components, killed/inactivated preparations, and live bacteria. Hi is a fastidious bacterium that requires enriched media but is generally easy to grow in standard laboratory settings. Tissue samples for stimulation with Hi may be obtained from peripheral blood, bronchoscopy, or resected lung (e.g., in patients undergoing surgery for the treatment of lung cancer). Macrophage and neutrophil function may be comprehensively assessed using flow cytometry with a variety of parameters measured, including phagocytosis, reactive oxygen species, and intracellular cytokine production. Lymphocyte function (e.g., T cell and NK cell function) may be specifically assessed using flow cytometry, principally for intracellular cytokine production. Hi infection is a potent inducer of extracellular trap production, both by neutrophils (NETs) and macrophages (METs). Confocal microscopy is arguably the most optimal way to assess NET and MET expression, which may also be used to assess protease activity. Lung immunity to Haemophilus influenzae can be assessed using flow cytometry and confocal microscopy.

Assessing Respiratory Immune Responses to Haemophilus Influenzae

Haemophilus influenzae induces inflammation in the respiratory tract. This article will focus on the use of flow cytometry and confocal microscopy to define immune responses by phagocytes and lymphocytes in response to this bacterium.

Haemophilus influenzae (Hi) is a prevalent bacterium found in a range of respiratory conditions. A variety of different assays/techniques may be used to ...

Advanced Imaging of Lung Homing Human Lymphocytes in an Experimental In Vivo Model of Allergic Inflammation Based on Light-sheet Microscopy

Overwhelming tissue accumulation of highly activated immune cells represents a hallmark of various chronic inflammatory diseases and emerged as an attractive therapeutic target in the clinical management of affected patients. In order to further optimize strategies aiming at therapeutic regulation of pathologically imbalanced tissue infiltration of pro-inflammatory immune cells, it will be of particular importance to achieve improved insights into disease- and organ-specific homing properties of peripheral lymphocytes. The here described experimental protocol allows to monitor lung accumulation of fluorescently labeled and adoptively transferred human lymphocytes in the context of papain-induced pulmonary inflammation. In contrast to standard in vitro assays frequently used for the analysis of immune cell migration and chemotaxis, the now introduced in vivo setting takes into account lung-specific aspects of tissue organization and the influence of the complex inflammatory scenario taking place in the living murine organism. Moreover, three-dimensional cross-sectional light-sheet fluorescence microscopic imaging does not only provide quantitative data on infiltrating immune cells, but also depicts the pattern of immune cell localization within the inflamed lung. Overall, we are able to introduce an innovative technique of high value for immunological research in the field of chronic inflammatory lung diseases, which can be easily applied by following the provided step-by-step protocol.

The here introduced protocol allows characterization of the lung homing capacity of primary human lymphocytes under in vivo inflammatory conditions. Pulmonary infiltration of adoptively transferred human immune cells in a mouse model of allergic inflammation can be imaged and quantified by light-sheet fluorescence microscopy of chemically cleared lung tissue.

Noninvasive Sampling of Mucosal Lining Fluid for the Quantification of In Vivo Upper Airway Immune-mediator Levels

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