Name: identification and characterization of immunogenic rna species in hdm allergens that modulate eosinophilic lung inflammation
Uploaded: 2020-05-30T15:00:00
Description: Watch this Scientific Journal Video about Identification and Characterization of Immunogenic RNA Species in HDM Allergens that Modulate Eosinophilic Lung Inflammation at JoVE.com

We thank Ms. Karla Gorena for technical assistance in flow cytometry. L.S. is supported by the China Scholarship Council and Hunan Provincial Innovation Foundation for Postgraduate (CX201713068). H.H.A. is supported by the Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Sakaka, Saudi Arabia. X.D.L. is supported by the UT Health San Antonio School of Medicine Startup Fund and the Max and Minnei Voelcker Fund.

Experimental procedures described here were approved by the Institutional Animal Care and Use Committee of University of Texas Health San Antonio.
1. Dot blot to show the presence of dsRNA structures in HDM total RNA
<ol>
	<li>Total RNA isolation from allergens, insects, and non-insect allergens
	<ol>
		<li>Put HDM, insects, or non-insect animals collected alive or obtained commercially into 50 mL tubes, and quickly freeze with liquid-N2. Then store at -70 &#176;C for subsequent t...

<ol>
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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=Innate+Immunity+and+Asthma+Risk+in+Amish+and+Hutterite+Farm+Children.">Innate Immunity and Asthma Risk in Amish and Hutterite Farm Children.</a> New England Journal of Medicine. 375, 411-421 (2016).</li><li>Roers, A., Hiller, B., Hornung, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recognition+of+Endogenous+Nucleic+Acids+by+the+Innate+Immune+System.">Recognition of Endogenous Nucleic Acids by the Innate Immune System.</a> Immunity. 44, 739-754 (2016).</li><li>Schlee, M., Hartmann, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Discriminating+self+from+non-self+in+nucleic+acid+sensing.">Discriminating self from non-self in nucleic acid sensing.</a> Nature Reviews Immunology. 16, 566-580 (2016).</li><li>Wu, J., Chen, Z. 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The current protocol describes how to evaluate the immunostimulatory properties of allergen-associated microbial RNA and their impacts on the development of eosinophilic lung inflammation in a mouse model of allergic asthma. Although long dsRNAs are known as the replication intermediates of many viruses that can potently activate interferon responses in mammalian cells, their presences in HDM allergens have been unknown until our recent work15. The combination of RNA dot blot, RT-qPCR and FACS ana...

Based on the hygiene hypothesis originally proposed by Strachan1, early childhood exposure to environmental microbial factors such as endotoxin can protect against the development of allergic disorders2,3. During microbial infections, e.g., viral infections, the innate immune detection of foreign nucleic acids (RNA/DNA) triggers host defense responses4,5,6. However, the existence and prevalence of immunogenic nucleic acids such as long double-stranded RNA (dsRNA) species in house dust mites (HDM) or other insect allergens remain unknown. This protocol was designed to determine whether HDM or insect and non-insect allergens contain long dsRNA species that can activate a protective immune response to counteract the development of severe eosinophilic lung inflammation in a mouse model of allergic asthma. Here, we provide three simple and fast methods to evaluate the structural determinants in HDM total RNA that are required for regulating allergen-induced eosinophilic lung inflammation.
The mucosal immune system is the largest immune organ in the body and serves as the first line of host defense against both microbial infections and allergic insults7,8. The long dsRNA, the replication intermediate of many viruses, is known to function as a pathogen-associated molecular pattern (PAMP) to potently stimulate innate responses via Toll like receptor 3 (TLR3) to induce the expression of interferon stimulated genes (ISGs)9,10,11,12,13,14. We have recently shown that HDM total RNA contained dsRNA structures, which upregulated the expression of ISGs and reduced severe eosinophilic lung inflammation when administered via the intratracheal instillation in a murine model of allergic asthma induced by HDM extracts15. The severity of lung inflammations is determined by analyzing the immune cell types in bronchoalveolar lavage (BAL) and lung tissue via flow cytometry16,17,18,19,20.
This protocol includes three assays: 1) rapid detection of dsRNA structures with RNA dot blot using a mouse monoclonal antibody J2 which specifically binds to the dsRNA (&#8805;40bp) in a sequence-independent manner; 2) quick evaluation for in vivo effects of immunostimulatory RNA in mouse lungs by measuring the induction of ISGs using RT-qPCR; 3) accurate quantification of eosinophils in BAL and lung in the context of HDM-induced lung inflammation using flow cytometry analysis.
The above assays can be used to study not only allergic lung diseases, but also respiratory bacterial and viral infections. For example, the dsRNA specific J2 antibody can also be used in other applications such as immunoaffinity chromatography, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA) and immunostaining21,22,23. In addition, several applications downstream of BAL fluid collection can be utilized for quantifying soluble contents such as cytokines and chemokines using ELISA, and transcriptional profiling of cells in the airways (e.g., alveolar macrophages). Although there are a variety of protocols available in the literature to evaluate lung conditions, most of these protocols often focus on the target validation. The procedures described here can be applied to identify components in environmental allergens that are important for regulating the development of allergic diseases.

<table>
	<tbody>
		<tr>
			<td>0.40 &#181;m Falcon Cell Strainer</td>
			<td>Thermo Fisher Scientific</td>
			<td>08-771-1</td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL syringes</td>
			<td>Henke Sass Wolf</td>
			<td>5010.200V0</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL Tube</td>
			<td>TH.Geyer</td>
			<td>7696702</td>
			<td></td>
		</tr>
		<tr>
			<td>50 mL Tube</td>
			<td>TH.Geyer</td>
			<td>7696705</td>
			<td></td>
		</tr>
		<tr>
			<td>70% ethanol</td>
			<td>Decon Labs</td>
			<td>2701</td>
			<td></td>
		</tr>
		<tr>
			<td>Absolute Counting Beads</td>
			<td>Life Technologies Europe B.V.</td>
			<td>C36950</td>
			<td></td>
		</tr>
		<tr>
			<td>ACK-RBC lysing buffer</td>
			<td>Lonza</td>
			<td>10-548E</td>
			<td></td>
		</tr>
		<tr>
			<td>Amersham Hybond-N+ Membrane</td>
			<td>GE Healthcare</td>
			<td>RPN203B</td>
			<td></td>
		</tr>
		<tr>
			<td>Ant</td>
			<td>San Antonio</td>
			<td>Note: Locally collected</td>
			<td></td>
		</tr>
		<tr>
			<td>Antibody dilution buffer</td>
			<td></td>
			<td>(see Table 5 for recipe)</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse CD11b V450 Rat (clone M1/70)</td>
			<td>BD Bioscience</td>
			<td>560456</td>
			<td>1 to 200 dilution</td>
		</tr>
		<tr>
			<td>Anti-Mouse CD11c PE-Cy7 (clone N418)</td>
			<td>BioLegend</td>
			<td>117317</td>
			<td>1 to 200 dilution</td>
		</tr>
		<tr>
			<td>Anti-Mouse CD19 Alexa Flour 647 (clone 1D3)</td>
			<td>eBioscience</td>
			<td>15-0193-81</td>
			<td>1 to 200 dilution</td>
		</tr>
		<tr>
			<td>Anti-Mouse CD3e APC (clone 145-2C11)</td>
			<td>Invitrogen</td>
			<td>15-0031-81</td>
			<td>1 to 200 dilution</td>
		</tr>
		<tr>
			<td>Anti-Mouse CD45 APC-Cy7 (clone: 30-F11)</td>
			<td>BioLegend</td>
			<td>103130</td>
			<td>1 to 200 dilution</td>
		</tr>
		<tr>
			<td>Anti-Mouse Fixable Viabillity Dye eFluor 506</td>
			<td>Invitrogen</td>
			<td>65-0866-14</td>
			<td>1 to 200 dilution</td>
		</tr>
		<tr>
			<td>Anti-Mouse IgG (H+L), AP Conjugate</td>
			<td>Promega</td>
			<td>S3721</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-Mouse Ly-6G FITC (clone RB6-8C5)</td>
			<td>Invitrogen</td>
			<td>11-5931-82</td>
			<td>1 to 200 dilution</td>
		</tr>
		<tr>
			<td>Anti-Mouse MHC II APC-eFluor 780 (clone M5/114.15.2)</td>
			<td>eBioscience</td>
			<td>47-5321-80</td>
			<td>1 to 200 dilution</td>
		</tr>
		<tr>
			<td>Anti-Mouse Siglec-F PE (clone E50-2440)</td>
			<td>BD Pharmingen</td>
			<td>552126</td>
			<td>1 to 200 dilution</td>
		</tr>
		<tr>
			<td>BCIP/NBT substrate</td>
			<td>Thermo Fisher Scientific</td>
			<td>PI34042</td>
			<td></td>
		</tr>
		<tr>
			<td>Blocking Buffer</td>
			<td></td>
			<td>(see Table 5 for recipe)</td>
			<td></td>
		</tr>
		<tr>
			<td>Cannual, 20G X 1.5&#8221;</td>
			<td>CADENCE SCIENCE</td>
			<td>9920</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Thermo Fisher Scientific</td>
			<td>75004030</td>
			<td></td>
		</tr>
		<tr>
			<td>CFX384 Touch Real-Time PCR Detection System</td>
			<td>Bio-Rad Laboratories</td>
			<td>1855485</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloroform</td>
			<td>Thermo Fisher Scientific</td>
			<td>C298-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Cockroach</td>
			<td>Greer Laboratories</td>
			<td>B26</td>
			<td></td>
		</tr>
		<tr>
			<td>Counting beads</td>
			<td>Thermo Fisher Scientific</td>
			<td>01-1234-42</td>
			<td></td>
		</tr>
		<tr>
			<td>D. farinae</td>
			<td>Greer Laboratories</td>
			<td>B81</td>
			<td></td>
		</tr>
		<tr>
			<td>D. pteronyssinus</td>
			<td>Greer Laboratories</td>
			<td>B82</td>
			<td></td>
		</tr>
		<tr>
			<td>Denville Cell Culture Plates with lid, 96 well cell culture plate</td>
			<td>Thomas Scientific</td>
			<td>1156F03</td>
			<td></td>
		</tr>
		<tr>
			<td>Digital Dry Bath - Four Blocks</td>
			<td>Universal Medical, Inc.</td>
			<td>BSH1004</td>
			<td></td>
		</tr>
		<tr>
			<td>Earthworm</td>
			<td>San Antonio</td>
			<td>Note: Locally collected</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid (EDTA)</td>
			<td>Sigma-Aldrich</td>
			<td>E6511</td>
			<td></td>
		</tr>
		<tr>
			<td>FACS buffer</td>
			<td></td>
			<td>(see recipe in Table 5)</td>
			<td></td>
		</tr>
		<tr>
			<td>Falcon Round-Bottom Polypropylene Tubes, 5 mL</td>
			<td>STEMCELLTM TECHNOLOGIES</td>
			<td>38056</td>
			<td></td>
		</tr>
		<tr>
			<td>Flow cytometer (BD FACS Celesta)</td>
			<td>BD Biosciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Fly</td>
			<td>Greer Laboratories</td>
			<td>B8</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Roboz Surgical Instrument</td>
			<td>RS-5135</td>
			<td></td>
		</tr>
		<tr>
			<td>Hemocytometer</td>
			<td>Hausser Scientific</td>
			<td>3110</td>
			<td></td>
		</tr>
		<tr>
			<td>HT-DNA</td>
			<td>Sigma</td>
			<td>D6898</td>
			<td></td>
		</tr>
		<tr>
			<td>In Vivo MAb anti-mouse CD16/CD32 (clone: 2.4G2)</td>
			<td>Bio X Cell</td>
			<td>BE0307</td>
			<td></td>
		</tr>
		<tr>
			<td>iScript cDNA Synthesis Kit</td>
			<td>Bio-Rad Laboratories</td>
			<td>1708891</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>Abbott Labs</td>
			<td>sc-363629Rx</td>
			<td></td>
		</tr>
		<tr>
			<td>Isopropanol</td>
			<td>Thermo Fisher Scientific</td>
			<td>BP2618500</td>
			<td></td>
		</tr>
		<tr>
			<td>J2 anti-dsRNA monoclonal antibody</td>
			<td>SCICONS</td>
			<td>10010200</td>
			<td></td>
		</tr>
		<tr>
			<td>Lung digestion solution</td>
			<td></td>
			<td>(see recipe in Table 5)</td>
			<td></td>
		</tr>
		<tr>
			<td>Lysing Matrix D</td>
			<td>MP Biomedicals</td>
			<td>116913050-CF</td>
			<td></td>
		</tr>
		<tr>
			<td>Lysing Matrix D, 2 mL tube</td>
			<td>MP Biomedicals</td>
			<td>SKU:116913100</td>
			<td></td>
		</tr>
		<tr>
			<td>Mice (female, 8-12 weeks old, C57BL/6J)</td>
			<td>Jackson Laboratory</td>
			<td>#000664</td>
			<td></td>
		</tr>
		<tr>
			<td>Microcentrifuge tube 1.5 mL</td>
			<td>Sigma-Aldrich</td>
			<td>30120.094</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Olympus</td>
			<td>CK30</td>
			<td></td>
		</tr>
		<tr>
			<td>Mini-BeadBeater</td>
			<td>Homogenizers</td>
			<td>SKU:BS:607</td>
			<td></td>
		</tr>
		<tr>
			<td>Mini-Beadbeater-16</td>
			<td>Biospec</td>
			<td>607</td>
			<td></td>
		</tr>
		<tr>
			<td>Mosquito</td>
			<td>Greer Laboratories</td>
			<td>B55</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoDrop 2000C</td>
			<td>Thermo Scientific Spectophotometer Medex Supply</td>
			<td>TSCND2000C</td>
			<td></td>
		</tr>
		<tr>
			<td>Needle, 21 G x 1 1/2 in</td>
			<td>BD Biosciences</td>
			<td>305167</td>
			<td></td>
		</tr>
		<tr>
			<td>Non-fat milk</td>
			<td>Bio-Rad Laboratories</td>
			<td>1706404</td>
			<td></td>
		</tr>
		<tr>
			<td>Nylon string</td>
			<td>Dynarex</td>
			<td>3243</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate-buffered Saline (PBS)</td>
			<td>Lonza</td>
			<td>BE17-516F</td>
			<td></td>
		</tr>
		<tr>
			<td>RNase III</td>
			<td>Thermo Fisher Scientific</td>
			<td>AM2290</td>
			<td></td>
		</tr>
		<tr>
			<td>RNase T1</td>
			<td>Thermo Fisher Scientific</td>
			<td>AM2283</td>
			<td></td>
		</tr>
		<tr>
			<td>Scissors</td>
			<td>Roboz Surgical Instrument</td>
			<td>RS-6802</td>
			<td></td>
		</tr>
		<tr>
			<td>Shaker or Small laboratory mixer</td>
			<td>Boekel Scientific</td>
			<td>201100</td>
			<td></td>
		</tr>
		<tr>
			<td>SPHERO AccuCount Fluorescent</td>
			<td>Spherotech</td>
			<td>ACFP-70-5</td>
			<td>1 to 10 dilution</td>
		</tr>
		<tr>
			<td>Spider</td>
			<td>San Antonio</td>
			<td>Note: Locally collected</td>
			<td></td>
		</tr>
		<tr>
			<td>TBS</td>
			<td></td>
			<td>(see recipe in Table 5)</td>
			<td></td>
		</tr>
		<tr>
			<td>TBS-T</td>
			<td></td>
			<td>(see recipe in Table 5)</td>
			<td></td>
		</tr>
		<tr>
			<td>Total cell medium</td>
			<td></td>
			<td>(see recipe in Table 5)</td>
			<td></td>
		</tr>
		<tr>
			<td>TRIzol Reagent</td>
			<td>Thermo Fisher Scientific</td>
			<td>15596018</td>
			<td></td>
		</tr>
		<tr>
			<td>Tween 20</td>
			<td>Sigma-Aldrich</td>
			<td>P9416</td>
			<td></td>
		</tr>
		<tr>
			<td>UV Stratalinker 2400 UV</td>
			<td>LabX</td>
			<td>20447</td>
			<td></td>
		</tr>
		<tr>
			<td>Wasp</td>
			<td>San Antonio</td>
			<td>Note: Locally collected</td>
			<td></td>
		</tr>
	</tbody>
</table>

identification and characterization of immunogenic rna species in hdm allergens that modulate eosinophilic lung inflammation

Environmental allergens such as house dust mites (HDM) are often in complex forms containing both allergic proteins that drive aberrant type 2 responses and microbial substances that induce innate immune responses. These allergen-associated microbial components play an important role in regulating the development of type 2 inflammatory conditions such as allergic asthma. However, the underlying mechanisms remain largely undefined. The protocol presented here determines the structural characteristics and in vivo activity of allergen-associated immunostimulatory RNA. Specifically, common allergens are examined for the presence of double-stranded RNA (dsRNA) species that can stimulate IFN responses in lungs and restrain&#160;the development of severe lung eosinophilia in a mouse model of HDM-induced allergic asthma. Here, we have included the following three assays: Dot blot to show the dsRNA structures in total RNA isolated from allergens including HDM species, RT-qPCR to measure the activities of HDM RNA in interferon stimulating genes (ISGs) expression in mouse lungs and FACS analysis to determine the effects of HDM RNA on the number of eosinophils in BAL and lung, respectively.

The presence of long dsRNA structures in HDM, insects and non-insect small animals was examined by dot blot using a dsRNA-specific mouse monoclonal antibody J2 (&#8805; 40bp). RNase III was used to digest dsRNA into 12&#8211;15 bp dsRNA fragments, which were undetectable by J2 (Figure 1).
The ability of HDM total RNA to stimulate an innate immune response in mouse lungs in a dose-dependent manner&#160;was analyzed by RT-qPCR (Figure 2...

Watch this Scientific Journal Video about Identification and Characterization of Immunogenic RNA Species in HDM Allergens that Modulate Eosinophilic Lung Inflammation at JoVE.com

Identification and Characterization of Immunogenic RNA Species in HDM Allergens that Modulate Eosinophilic Lung Inflammation

Environmental allergens such as house dust mites (HDM) often contain microbial substances that activate innate immune responses to regulate allergic inflammation. The protocol presented here demonstrates the identification of dsRNA species in HDM allergens and characterization of their immunogenic activities in modulating eosinophilic lung inflammation.

Environmental allergens such as house dust mites (HDM) are often in complex forms containing both allergic proteins that drive aberrant type 2 responses ...

This protocol was designed to address a very important and unsolved issue on how microbial substances present and environmental allergens can regulate the development of allergic inflammation. Specifically, the methods presented here can help answer whether double-stranded RNA species in house dust mites are immunogenic in vivo and able to modulate eosinophilic lung inflammation. The main advantages of these techniques are that they're simple, efficient, highly reproducible and can be performed using commonly used tools and equipment.These methods can also be used to evaluate lung diseases caused by respiratory viral infections. Li She, a graduate student in my laboratory, will help demonstrate the procedure. Begin by isolating total RNA from allergens, insects, and non-insect allergens.Transfer a proper amount of specimen into a two-milliliter tube containing 1.4 millimeters of ceramic beads, and freeze the tubes in a liquid nitrogen container for approximately 10 minutes. Add one milliliter of guanidinium thiocyanate-based RNA isolation reagent to each tube. Then break the insect and non-insect small animals with a high-energy cell disrupter at maximum speed for 45 seconds.Chill the sample on ice, and repeat this process twice. Transfer the solution into a new 1.5-milliliter tube. Add 200 microliters of chloroform to each tube, and vortex the sample.Centrifuge the tubes at 14, 000 times g for 14 minutes at four degrees Celsius. Then transfer the upper aqueous phase into a new tube containing 500 microliters of isopropanol. Mix the sample.Then centrifuge it at 14, 000 times g for 14 minutes at four degrees Celsius. Carefully aspirate the supernatant. Then wash the RNA pellet with 500 microliters of 75%ethanol, and centrifuge it at 7, 500 times g for 10 minutes at four degrees Celsius.Carefully remove all liquid. Air-dry the pellet, and dissolve the RNA with 20 to 50 microliters of RNase-free water. To detect the double-stranded RNA structures in the total RNA, spot two microliters of the 200-nanogram-per-microliter RNA sample onto the positively charged nylon membrane.Crosslink the samples to the membrane at 1, 200 microjoules by 100 in a UV crosslinker. Repeat the spotting and crosslinking two more times, which will result in a total of 1.2 micrograms of RNA per blot. Block non-specific binding with 5%milk in TBS-T for one hour while shaking at room temperature.Then remove the blocking solution, and add the anti-double-stranded RNA J2 antibody at a one-to-1, 000 dilution in 1%milk in TBS-T. Incubate the membrane overnight with shaking at four degrees Celsius. On the next day, wash the membrane three times with TBS-T for five minutes per wash.Add the secondary antibody, and incubate the membrane for one hour at room temperature. Then repeat the washes with TBS-T. Add the substrate, and incubate the membrane for five to 15 minutes until a desired signal is visible.Stop the reaction by rinsing the membrane with double-distilled water. To collect the lung samples, place the lungs on tissue papers, and excise one small piece of each lung lobe. Place each piece into a two-milliliter tube containing beads.To collect bronchoalveolar lavage, disinfect a euthanized mouse with 70%ethanol, and use scissors to cut the skin from the upper area of the abdomen to the neck. Gently pull the salivary glands and the sternohyoid muscle apart with forceps to expose the trachea. Then place a nylon string beneath it.Make an incision in the trachea approximately two milliliters under the larynx just enough to insert a cannula, and knot the string around the trachea and cannula. Attach a syringe to the end of the cannula, and load it with fresh PBS-EDTA. Then inject and aspirate one milliliter of the solution into the lung.Detach the syringe from the cannula, and eject the solution into a 15-milliliter tube. Repeat this process to ice with fresh PBS-EDTA, and pool the lavage. Centrifuge the tube at 500 times g for seven minutes at four degrees Celsius.Then record the volume, and transfer the supernatant to two 1.5-milliliter tubes without disturbing the pellet. After resuspending the pellet, transfer 150 microliters into a 96-well plate, and centrifuge the plate for seven minutes at 500 times g and four degrees Celsius. Then quickly invert the plate on tissue paper to remove the supernatant.Stain the cells with antibodies in FACS buffer in the presence of 2.4G2 blocking antibody, and incubate the plate at room temperature for 30 minutes in the dark. After staining, centrifuge the plate to pellet the cells at 500 times g for seven minutes at four degrees Celsius. Remove the staining solution by inverting the plate on tissue paper.Add 100 microliters of FACS buffer to wash the cells, and then repeat the centrifugation. Resuspend the samples in 150 microliters of FACS buffer, and then transfer them to FACS tubes containing an additional 350 microliters of buffer. Add 25 microliters of counting beads to each sample, and proceed with flow cytometry analysis.The presence of long double-stranded RNA structures in house dust mites, insects, and non-insect small animals was examined by dot blot using a double-stranded, RNA-specific mouse monoclonal antibody. RNase III was used to digest the double-stranded RNA into 12 to 15 base pair fragments, which were undetectable by J2.The ability of house dust mite total RNA to stimulate an innate immune response in mouse lungs was demonstrated by RT-qPCR. The RNase III treatment abolished the immunostimulatory activity of house dust mite total RNA, indicating that the double-stranded RNA structures are essential for innate immune activity in the lungs.The inhibitory effect of house dust mite total RNA on the development of a severe type two lung inflammation were evaluated with FACS analysis. The eosinophilic lung inflammation was induced by dust mite extracts, which were treated with or without RNase III. The degradation of long double-stranded RNA species resulted in severe type two lung inflammation, reflected by the increased eosinophil numbers in bronchoalveolar lavage and lungs.Notably, the number of eosinophils in the dust mite total RNA-treated group is comparable to the group treated with the original dust mite extract that endogenously contained the long double-stranded RNA species. When attempting this protocol, be very careful when injecting and recollecting the BAL fluid, as any damage to the lungs at this stage may alter the final results. In addition to this procedure, other methods like ELISA can be performed to analyze non-cellular soluble contents present in the BAL fluid.After its development, this technique paved the way for researchers to explore other microbial substances present in environmental allergens, such as non-double-stranded RNA factors that can regulate the development of allergic lung inflammation.

Research

JoVE Journal

Immunology and Infection

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