Name: separation of rat epidermis and dermis with thermolysin to detect site-specific inflammatory mrna and protein
Uploaded: 2021-09-29T13:00:00
Description: Watch this Scientific Journal Video about Separation of Rat Epidermis and Dermis with Thermolysin to Detect Site-Specific Inflammatory mRNA and Protein at JoVE.com

Funding for this research was provided by National Institutes of Health NIH-AR047410 (KEM)

This protocol follows the animal care guidelines of Oklahoma State University Center for Health Sciences IACUC (#2016-03).
1. Carrageenan-induced inflammation (C-II)
<ol>
	<li>Anesthetize male and/or female Sprague Dawley rats (200&#8211;250 g; 8&#8211;9 weeks old) with isoflurane (or injectable anesthetic).</li>
	<li>Check the depth of anesthesia by touching the cornea and lightly pinching the left hind paw. When the animal is appropriately anesthetized, no corneal or paw response will be o...

<ol>
	<li>Choi, J. E., Di Nardo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Skin+neurogenic+inflammation.">Skin neurogenic inflammation.</a> Seminars in Immunopathology. 40 (3), 249-259 (2018).</li><li>Manti, S., Brown, P., Perez, M. K., Piedimonte, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+neurotrophins+in+inflammation+and+allergy.">The role of neurotrophins in inflammation and allergy.</a> Vitamins and Hormones. 104, 313-341 (2017).</li><li>Sch&#228;kel, K., Sch&#246;n, M. 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I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dermal-epidermal+separation+methods:+research+implications.">Dermal-epidermal separation methods: research implications.</a> Archives of Dermatological Research. 310 (1), 1-9 (2018).</li><li>Baumberger, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methods+for+the+separation+of+epidermis+from+dermis+and+some+physiologic+and+chemical+properties+of+isolated+epidermis.">Methods for the separation of epidermis from dermis and some physiologic and chemical properties of isolated epidermis.</a> Journal of the National Cancer Institute. 2, 413-423 (1942).</li><li>Felsher, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Studies+on+the+adherence+of+the+epidermis+to+the+corium.">Studies on the adherence of the epidermis to the corium.</a> Journal of Investigative Dermatology. 8, 35-47 (1947).</li><li>Einbinder, J. M., Walzer, R. A., Mandl, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidermal-dermal+separation+with+proteolytic+enzymes.">Epidermal-dermal separation with proteolytic enzymes.</a> Journal of Investigative Dermatology. 46, 492-504 (1966).</li><li>Rakhorst, H. 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=Mucosal+keratinocyte+isolation:+a+short+comparative+study+on+thermolysin+and+dispase.">Mucosal keratinocyte isolation: a short comparative study on thermolysin and dispase.</a> International Association of Oral and Maxillofacial Surgeons. 35 (10), 935-940 (2006).</li><li>Tschachler, E., 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=Sheet+preparations+expose+the+dermal+nerve+plexus+of+human+skin+and+render+the+dermal+nerve+end+organ+accessible+to+extensive+analysis.">Sheet preparations expose the dermal nerve plexus of human skin and render the dermal nerve end organ accessible to extensive analysis.</a> Journal of Investigative Dermatology. 122 (1), 177-182 (2004).</li><li>Walzer, C., Benathan, M., Frenk, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thermolysin+treatment-a+new+method+for+dermo-epidermal+separation.">Thermolysin treatment-a new method for dermo-epidermal separation.</a> Journal of Investigative Dermatology. 92, 78-81 (1989).</li><li>Anderson, M. B., Miller, K. E., Schechter, R. <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+rat+epidermis+and+dermis+following+thermolysin+separation:+PGP+9.5+and+Nav+1.8+localization.">Evaluation of rat epidermis and dermis following thermolysin separation: PGP 9.5 and Nav 1.8 localization.</a> Society for Neuroscience Abstract. 584 (9), (2010).</li><li>Ibitokun, B. O., Anderson, M. B., Miller, K. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Separation+of+corneal+epithelium+from+the+stroma+using+thermolysin:+evaluation+of+corneal+afferents.">Separation of corneal epithelium from the stroma using thermolysin: evaluation of corneal afferents.</a> Society for Neuroscience Abstract. , 584 (2010).</li><li>Nawani, P., Anderson, M., Miller, K. 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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=Carrageenan-induced+thermal+hyperalgesia+in+the+mouse:+role+of+nerve+growth+factor+and+the+mitogen-activated+protein+kinase+pathway.">Carrageenan-induced thermal hyperalgesia in the mouse: role of nerve growth factor and the mitogen-activated protein kinase pathway.</a> Brain Research. 876 (1-2), 48-54 (2000).</li><li>Hoffman, E. M., Miller, K. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peripheral+inhibition+of+glutaminase+reduces+carrageenan+induced+Fos+expression+in+the+superficial+dorsal+horn+of+the+rat.">Peripheral inhibition of glutaminase reduces carrageenan induced Fos expression in the superficial dorsal horn of the rat.</a> Neuroscience Letters. 472 (3), 157-160 (2010).</li><li>Crosby, H. A., Ihnat, M., Spencer, D., Miller, K. 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E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fixative+composition+alters+distributions+of+immunoreactivity+for+glutaminase+and+two+markers+of+nociceptive+neurons+Nav1.8+and+TRPV1,+in+the+rat+dorsal+ganglion.">Fixative composition alters distributions of immunoreactivity for glutaminase and two markers of nociceptive neurons Nav1.8 and TRPV1, in the rat dorsal ganglion.</a> Journal of Histochemistry and Cytochemistry. 58 (4), 329-344 (2010).</li><li>Hoffman, E. M., Zhang, Z., Schechter, R., Miller, K. 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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=Multiparameter+flow+cytometric+characterization+of+epidermal+cell+suspensions+prepared+from+normal+and+hyperproliferative+human+skin+using+an+optimized+thermolysin-trypsin+protocol.">Multiparameter flow cytometric characterization of epidermal cell suspensions prepared from normal and hyperproliferative human skin using an optimized thermolysin-trypsin protocol.</a> Archives of Dermatological Research. 288 (4), 203-210 (1996).</li><li>Sato, J. D., Kan, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Media+for+culture+of+mammalian+cells.">Media for culture of mammalian cells.</a> Current Protocols in Cell Biology. , (2001).</li><li>Gragnani, A., Sobral, C. S., Ferreira, L. 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Animal. 35 (6), 318-326 (1999).</li><li>Fassina, 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=Autolysis+of+thermolysin.+Isolation+and+characterization+of+a+folded+three-fragment+complex.">Autolysis of thermolysin. Isolation and characterization of a folded three-fragment complex.</a> European Journal of Biochemistry. 156 (2), 221-228 (1986).</li><li>Petho, G., Reeh, P. 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The study determined that the epidermis of rat hind paw glabrous skin was easily separated from dermis using thermolysin (0.5 mG/mL) in PBS with 1 mM calcium chloride at 4 &deg;C for 2.5 h. Histological evaluation indicated that the epidermis was separated from the dermis at the basement membrane and that the epidermal rete ridges were intact. Thermolysin is an extracellular metalloendopeptidase produced by Gram-positive (Geo)Bacillus thermoproteolyticus24. Its activity is stable...

Evaluation of inflammatory mediators and neurotrophic factors from the skin can be limited due to the heterogeneity of cell types found in the inflamed dermis and epidermis1,2,3. Several enzymes, chemical, thermal, or mechanical techniques involving separation of the two layers or for performing cell dissociation for evaluation have been reviewed recently4. Acid, alkali, neutral salt, and heat can divide the epidermis from dermis quickly, but cellular and extracellular swelling often occurs5,6. Trypsin, pancreatin, elastase, keratinase, collagenase, pronase, dispase, and thermolysin are enzymes that have been used for epidermal-dermal separation4,7. Trypsin and other broad scale proteolytic enzymes are active at 37&ndash;40 &deg;C but must be monitored carefully to prevent dissociation of epidermal layers. Dispase cleaves the epidermis at the lamina densa, but requires 24 h for separation in the cold4,8 or shorter timepoints at 37 &deg;C4,9. A limiting feature of all these techniques is the potential disruption of tissue morphology and loss of integrity of mRNA and protein.
To maintain the integrity of mRNA and protein, a skin separation method should be carried out in the cold for a short period of time. In evaluating skin separation techniques for inflammation studies, thermolysin is an effective enzyme to separate the epidermis from dermis at cold temperatures4. Thermolysin is active at 4 &deg;C, cleaves epidermal hemidesmosomes from the lamina lucida, and separates the epidermis from dermis within 1&ndash;3 h4,8,10. The goal of this report is to optimize the use of thermolysin for separation of inflamed rat epidermis from dermis to detect mRNA and protein levels for inflammatory mediators and neurotrophic factors. Several preliminary reports have been presented11,12,13,14,15. The objective of this manuscript is to describe an optimal skin separation technique using thermolysin and demonstrate the detection of 1) markers of inflammation, 2) interleukin-6 (IL-6) mRNA, and 3) nerve growth factor (NGF) mRNA and protein in the epidermis of rats with carrageenan-induced inflammation (C-II)16,17. A preliminary report using the complete Freund&rsquo;s adjuvant model indicates that NGF mRNA and protein levels increase early during inflammation15. In mice, skin sensitization with the topical application of oxazolone causes an early rise in the IL-6 mRNA using in situ hybridization36. Both IL-6 and NGF have been implicated in C-II18,19, but there have been no reports describing mRNA or protein levels for IL-6 or NGF specifically from the epidermis during the acute stages of C-II.
The thermolysin technique is inexpensive and straightforward to perform. Furthermore, thermolysin separation of the epidermis from dermis allows for mRNA, western blot, and immunohistochemical analysis of inflammatory mediators and neurotrophic factors during the process of inflammation15. Investigators should be able to easily use this technique in both preclinical and clinical studies of skin inflammation.

<table>
	<tbody>
		<tr>
			<td>&#955;-carrageenan</td>
			<td>Millipore Sigma</td>
			<td>22049</td>
			<td>Subcutaneous injection of carrageenan induces inflammation</td>
		</tr>
		<tr>
			<td>7500 Fast Real-Time PCR System</td>
			<td>Thermo Fisher Scientific</td>
			<td>4351107</td>
			<td>For RT-PCR analysis</td>
		</tr>
		<tr>
			<td>Calcium chloride (CaCl2), anhydrous</td>
			<td>Millipore Sigma</td>
			<td>499609</td>
			<td>Prevents autolysis of thermolysin</td>
		</tr>
		<tr>
			<td>Crystal Mount Aqueous Mounting Medium</td>
			<td>Millipore Sigma</td>
			<td>C0612</td>
			<td>Aqueous mounting medium after toluidine blue staining</td>
		</tr>
		<tr>
			<td>Donkey anti-Mouse Alexa Fluor 555</td>
			<td>Thermo Fisher Scientific</td>
			<td>A-31570</td>
			<td>Secondary antibody for immunohistochemistry</td>
		</tr>
		<tr>
			<td>Donkey anti-Rabbit IgG, Alexa Fluor 488</td>
			<td>Thermo Fisher Scientific</td>
			<td>A-21206</td>
			<td>Secondary antibody for immunohistochemistry</td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle Medium</td>
			<td>Thermo Fisher Scientific</td>
			<td>11966-025</td>
			<td>To maintain tissue integrity</td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid</td>
			<td>Millipore Sigma</td>
			<td>E6758</td>
			<td>Stops thermolysin reaction</td>
		</tr>
		<tr>
			<td>Moloney Murine Leukemia Virus (M-MLV) Reverse transcriptase</td>
			<td>Promega</td>
			<td>M1701</td>
			<td>For complementary DNA synthesis</td>
		</tr>
		<tr>
			<td>Mouse anti-NGF Antibody (E-12)</td>
			<td>Santa Cruz Biotechnology</td>
			<td>sc-365944</td>
			<td>For neurotrophin immunohistochemistry</td>
		</tr>
		<tr>
			<td>ProLong Gold Antifade Mountant</td>
			<td>Thermo Fisher Scientific</td>
			<td>P36930</td>
			<td>To retard immunofluorescence quenching</td>
		</tr>
		<tr>
			<td>Rabbit anti-PGP 9.5</td>
			<td>Cedarlane Labs</td>
			<td>CL7756AP</td>
			<td>For intraepidermal nerve staining</td>
		</tr>
		<tr>
			<td>SAS Sprague Dawley Rat</td>
			<td>Charles River</td>
			<td>Strain Code 400</td>
			<td>Animal used for inflammation studies</td>
		</tr>
		<tr>
			<td>Shandon M-1 Embedding Matrix</td>
			<td>Thermo Fisher Scientific</td>
			<td>1310TS</td>
			<td>Tissue embedding matrix for tinctorial- and immuno-histochemistry</td>
		</tr>
		<tr>
			<td>SimpliAmp Thermal Cycler</td>
			<td>Thermo Fisher Scientific</td>
			<td>A24811</td>
			<td>For RT-PCR analysis</td>
		</tr>
		<tr>
			<td>SYBR Select Master Mix</td>
			<td>Thermo Fisher Scientific</td>
			<td>4472908</td>
			<td>For RT-PCR analysis</td>
		</tr>
		<tr>
			<td>Thermolysin</td>
			<td>Millipore Sigma</td>
			<td>T7902</td>
			<td>From Geobacillus stearothermophilus</td>
		</tr>
		<tr>
			<td>Toluidine Blue</td>
			<td>Millipore Sigma</td>
			<td>89640</td>
			<td>For tinctorial staining for brightfield microscopy</td>
		</tr>
		<tr>
			<td>TRIzol Reagent</td>
			<td>Thermo Fisher Scientific</td>
			<td>15596026</td>
			<td>For total RNA extraction for RTPCR</td>
		</tr>
	</tbody>
</table>

separation of rat epidermis and dermis with thermolysin to detect site-specific inflammatory mrna and protein

Easy-to-use and inexpensive techniques are needed to determine the site-specific production of inflammatory mediators and neurotrophins during skin injury, inflammation, and/or sensitization. The goal of this study is to describe an epidermal-dermal separation protocol using thermolysin, a proteinase that is active at 4 &deg;C. To illustrate this procedure, Sprague Dawley rats are anesthetized, and right hind paws are injected with carrageenan. Six and twelve hours after injection, rats with inflammation and na&iuml;ve rats are euthanized, and a piece of hind paw, glabrous skin is placed in cold Dulbecco's Modified Eagle Medium. The epidermis is then separated at the basement membrane from the dermis by thermolysin in PBS with calcium chloride. Next, the dermis is secured by microdissection forceps, and the epidermis is gently teased away. Toluidine blue staining of tissue sections show that the epidermis is separated cleanly from the dermis at the basement membrane. All keratinocyte cell layers remain intact, and the epidermal rete ridges along with indentations from dermal papillae are clearly observed. Qualitative and real-time RT-PCR is used to determine nerve growth factor and interleukin-6 expression levels. Western blotting and immunohistochemistry are finally performed to detect amounts of nerve growth factor. This report illustrates that cold thermolysin digestion is an effective method to separate epidermis from dermis for evaluation of mRNA and protein alterations during inflammation.

Carrageenan injection into the rat hind paw caused classic symptoms of inflammation such as redness and edema16,17. The swelling of the hind paw was measured with mechanical calipers20. A baseline value of the thickness of the paw was obtained for each rat before carrageenan treatment and measured again at 6 h and 12 h. Paw thickness was increased significantly compared to the baseline values (Figure 1).
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Separation of Rat Epidermis and Dermis with Thermolysin to Detect Site-Specific Inflammatory mRNA and Protein

Presented here is a protocol for the separation of epidermis from dermis to evaluate inflammatory mediator production. Following inflammation, rat hind paw epidermis is separated from the dermis by thermolysin at 4 &#176;C. The epidermis is then used for mRNA analysis by RT-PCR and protein evaluation by western blot and immunohistochemistry.

Easy-to-use and inexpensive techniques are needed to determine the site-specific production of inflammatory mediators and neurotrophins during skin ...

Our protocol is an easy-to-use and inexpensive epidermal-dermal separation technique for determining the site-specific production of inflammatory mediators and neurotrophins during skin inflammation. The main advantage of this technique is that enzymatic separation of the epidermis from the dermis is performed at four degrees Celsius, maintaining the integrity of mRNA and protein. This method provides insight into the types of mediators that sensitize primary afferent terminals during acute and chronic inflammation for the development of novel therapeutic interventions.Wound healing, skin disease, chronic wounds, and burns could benefit from this research. And this method could be applied to other epithelial surfaces, such as the GI tract and cornea. The optimal separation time may differ slightly between labs.A preliminary experiment comparing different time points combined with a 2D morphology evaluation is recommended to determine the quality of the separation. After confirming a lack of response to pedal reflex in an anesthetized eight to nine-week-old Sprague Dawley rat, subcutaneously inject the right glabrous hind paw with 100 microliters of 1X Lambda carrageenan diluted in PBS. Use calipers to measure the hind paw metatarsal thickness immediately before and at 6 and 12 hours after injection to determine the volume of edema in response to the stimulus.At the appropriate experimental endpoint, use a sharp scalpel to harvest a one by two millimeter piece of glabrous hind paw skin from the injected paw and use microdissection forceps to transfer the skin into one milliliter of cold DMEM in a microcentrifuge tube on ice for 15 to 60 minutes. While the tissue is incubating, add one milliliter of freshly prepared activated thermolysin to 10 wells of a 24-well cell culture plate on ice. At the end of the incubation, use the microdissection forceps to transfer one skin sample into each well of activated thermolysin, stratum corneum side up without immersing the samples in the solution.It is critical that the skin is not immersed in the thermolysin and that the stratum corneum faces up to achieve an effective separation. After two to three hours, use the microdissection forceps to immerse one skin sample in seven to eight milliliters of four degrees Celsius DMEM in a Petri dish to allow more room for the epidermis to separate from the dermis. Use forceps to gently brush the epidermis around the perimeter of the skin until the near translucent epidermis is observed at the borders of the sample.When the epidermis noticeably separates from the dermis, carefully grasp each layer of skin with a single pair of forceps and slowly pull the epidermis from the dermis, then evaluate the translucence of the isolated epidermis by light microscopy to make sure it is optically consistent. If the layers have been properly separated, place the epidermal and dermal tissues into individual containers of five millimolar EDTA in DMEM at four degrees Celsius for 30 minutes. After thermolysin deactivation, fix a portion of the epidermis in an appropriate fixative for one hour at room temperature with agitation.At the end of the incubation, place the fixed tissue in 10%sucrose in PBS for one hour at room temperature with agitation, before freezing the sample in a suitable tissue embedding matrix for sectioning. Use a cryostat to obtain 14 micrometer thick cross-sections and thaw mount the sections onto gelatin-coated glass microscope slides. After drying on a slide warmer, stain the samples with a working solution of toluidine blue for 90 seconds.Afterward, gently wash toluidine blue from the slides with PBS and oppose coverslips with an aqueous mounting medium, then observe the epidermis with Brightfield microscopy at a 50 to 250X magnification. Carrageenan injection into the rat hind paw causes classic symptoms of inflammation, such as redness and edema at both 6 and 12-hour post-injection. Brightfield microscopy can be used to evaluate the effectiveness of thermolysin separation of the epidermis and dermis of the rat glabrous hind paw skin.Indeed, toluidine blue staining of the epidermal cross-sections shows that the epidermis is separated from the dermis at the baseline membrane, but that the epidermal Rete ridges and the indentations from the dermal papilla remain intact. Further, all of the keratinocyte cell layers are observed. Western blotting of the thermolysin separated epidermis produces consistent results, indicating stable protein levels during the technique at four degrees Celsius.Very little NGF protein is detected in the naive rat epidermis, but NGF protein levels are significantly upregulated after six hours of carrageenan-induced inflammation. 12 hours after the injection, NGF levels are reduced compared to those observed at six hours, but remain elevated relative to controls. As expected from the Western blot analysis, NGF immunoreactivity is not detected at naive control epidermis tissue samples, but at six hours post carrageenan-induced inflammation, NGF immunoreactivity is observed in most of the keratinocytes of the stratum granulosum and stratum lucidum.A few cells in the stratum spinosum are also NGF immunoreactive. When using thermolysin to isolate the intact epidermis, it is important to remember that the optimal separation time must be empirically determined by the end user. Various proteomic and molecular techniques can be used to validate the expression of specific proteins and/or primary gene transcripts to confirm that this procedure does not alter the basal expression.This technique of epidermal-dermal separation will allow researchers to answer additional questions regarding the site-specific expression of neurotrophins and inflammatory mediators in different cutaneous inflammatory models. Picric acid and paraformaldehyde are hazardous. Work with both chemicals in a fume hood, use personal protective clothing and gloves and wash your face and hands after handling.

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Research

JoVE Journal

Immunology and Infection

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae

Nasopharyngeal colonization by Streptococcus pneumoniae is a prerequisite to invasion to the lungs or bloodstream1. This organism is capable of colonizing the mucosal surface of the nasopharynx, where it can reside, multiply and eventually overcome host defences to invade to other tissues of the host. Establishment of an infection in the normally lower respiratory tract results in pneumonia. Alternatively, the bacteria can disseminate into the bloodstream causing bacteraemia, which is associated with high mortality rates2, or else lead directly to the development of pneumococcal meningitis. Understanding the kinetics of, and immune responses to, nasopharyngeal colonization is an important aspect of S. pneumoniae infection models.
Our mouse model of intranasal colonization is adapted from human models3 and has been used by multiple research groups in the study of host-pathogen responses in the nasopharynx4-7. In the first part of the model, we use a clinical isolate of S. pneumoniae to establish a self-limiting bacterial colonization that is similar to carriage events in human adults. The procedure detailed herein involves preparation of a bacterial inoculum, followed by the establishment of a colonization event through delivery of the inoculum via an intranasal route of administration. Resident macrophages are the predominant cell type in the nasopharynx during the steady state. Typically, there are few lymphocytes present in uninfected mice8, however mucosal colonization will lead to low- to high-grade inflammation (depending on the virulence of the bacterial species and strain) that will result in an immune response and the subsequent recruitment of host immune cells. These cells can be isolated by a lavage of the tracheal contents through the nares, and correlated to the density of colonization bacteria to better understand the kinetics of the infection.

Characterization of Inflammatory Responses During Intranasal Colonization with Streptococcus pneumoniae

Colonization of the murine nasopharynx with Streptococcus pneumoniae and the subsequent extraction of adherent or recruited cells is described. This technique involves flushing the nasopharynx and collection of the fluid through the nares and is adaptable for various readouts, including differential cell quantification and analysis of mRNA expression in situ.

Nasopharyngeal colonization by Streptococcus pneumoniae is a prerequisite to invasion to the lungs or bloodstream1. This organism is capable of colonizing ...

Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking

This article describes a method to detect and analyze dynamic interactions between a protein of interest and other factors in vivo. Our method is based on the amber suppression technology that was originally developed by Peter Schultz and colleagues1. An amber mutation is first introduced at a specific codon of the gene encoding the protein of interest. The amber mutant is then expressed in E. coli together with genes encoding an amber suppressor tRNA and an amino acyl-tRNA synthetase derived from Methanococcus jannaschii. Using this system, the photo activatable amino acid analog p-benzoylphenylalanine (Bpa) is incorporated at the amber codon. Cells are then irradiated with ultraviolet light to covalently link the Bpa residue to proteins that are located within 3-8 &#197;. Photocrosslinking is performed in combination with pulse-chase labeling and immunoprecipitation of the protein of interest in order to monitor changes in protein-protein interactions that occur over a time scale of seconds to minutes. We optimized the procedure to study the assembly of a bacterial virulence factor that consists of two independent domains, a domain that is integrated into the outer membrane and a domain that is translocated into the extracellular space, but the method can be used to study many different assembly processes and biological pathways in both prokaryotic and eukaryotic cells. In principle interacting factors and even specific residues of interacting factors that bind to a protein of interest can be identified by mass spectrometry.

This article illustrates the use of pulse-chase radio labeling in combination with site-specific photocrosslinking to monitor interactions between a protein of interest and other factors in E. coli. Unlike traditional chemical cross-linking methods, this approach generates high resolution &#8220;snapshots&#8221; of an ordered assembly pathway in a living cell.

This article describes a method to detect and analyze dynamic interactions between a protein of interest and other factors in vivo. Our method is based on ...

Ex Vivo Infection of Murine Epidermis with Herpes Simplex Virus Type 1

To enter its human host, herpes simplex virus type 1 (HSV-1) must overcome the barrier of mucosal surfaces, skin, or cornea. HSV-1 targets keratinocytes during initial entry and establishes a primary infection in the epithelium, which is followed by latent infection of neurons. After reactivation, viruses can become evident at mucocutaneous sites that appear as skin vesicles or mucosal ulcers. How HSV-1 invades skin or mucosa and reaches its receptors is poorly understood. To investigate the invasion route of HSV-1 into epidermal tissue at the cellular level, we established an ex vivo infection model of murine epidermis, which represents the site of primary and recurrent infection in skin. The assay includes the preparation of murine skin. The epidermis is separated from the dermis by dispase II treatment. After floating the epidermal sheets on virus-containing medium, the tissue is fixed and infection can be visualized at various times postinfection by staining infected cells with an antibody against the HSV-1 immediate early protein ICP0. ICP0-expressing cells can be observed in the basal keratinocyte layer already at 1.5 hr postinfection. With longer infection times, infected cells are detected in suprabasal layers, indicating that infection is not restricted to the basal keratinocytes, but the virus spreads to other layers in the tissue. Using epidermal sheets of various mouse models, the infection protocol allows determining the involvement of cellular components that contribute to HSV-1 invasion into tissue. In addition, the assay is suitable to test inhibitors in tissue that interfere with the initial entry steps, cell-to-cell spread and virus production. Here, we describe the ex vivo infection protocol in detail and present our results using nectin-1- or HVEM-deficient mice.

Ex Vivo Infection of Murine Epidermis with Herpes Simplex Virus Type 1

The skin is one target tissue of the human pathogen herpes simplex virus type 1 (HSV-1). To explore the invasion route of HSV-1 into tissue, we established an ex vivo infection model of murine epidermal sheets which represent the outermost layer of skin.

To enter its human host, herpes simplex virus type 1 (HSV-1) must overcome the barrier of mucosal surfaces, skin, or cornea. HSV-1 targets keratinocytes ...

Imaging CD4 T Cell Interstitial Migration in the Inflamed Dermis

The ability of CD4 T cells to carry out effector functions is dependent upon the rapid and efficient migration of these cells in inflamed peripheral tissues through an as-yet undefined mechanism. The application of multiphoton microscopy to the study of the immune system provides a tool to measure the dynamics of immune responses within intact tissues. Here we present a protocol for non-invasive intravital multiphoton imaging of CD4 T cells in the inflamed mouse ear dermis. Use of a custom imaging platform and a venous catheter allows for the visualization of CD4 T cell dynamics in the dermal interstitium, with the ability to interrogate these cells in real-time via the addition of blocking antibodies to key molecular components involved in motility. This system provides advantages over both in vitro models and surgically invasive imaging procedures. Understanding the pathways used by CD4 T cells for motility may ultimately provide insight into the basic function of CD4 T cells as well as the pathogenesis of both autoimmune diseases and pathology from chronic infections.

The mechanisms that govern the interstitial motility of CD4 effector T cells at sites of inflammation are relatively unknown. We present a non-invasive approach to visualize and manipulate in vitro-primed CD4 T cells in the inflamed ear dermis, allowing for study of the dynamic behavior of these cells in situ.

The ability of CD4 T cells to carry out effector functions is dependent upon the rapid and efficient migration of these cells in inflamed peripheral ...

Bioluminescence Imaging to Detect Late Stage Infection of African Trypanosomiasis

Human African trypanosomiasis (HAT) is a multi-stage disease that manifests in two stages; an early blood stage and a late stage when the parasite invades the central nervous system (CNS). In vivo study of the late stage has been limited as traditional methodologies require the removal of the brain to determine the presence of the parasites.
Bioluminescence imaging is a non-invasive, highly sensitive form of optical imaging that enables the visualization of a luciferase-transfected pathogen in real-time. By using a transfected trypanosome strain that has the ability to produce late stage disease in mice we are able to study the kinetics of a CNS infection in a single animal throughout the course of infection, as well as observe the movement and dissemination of a systemic infection.
Here we describe a robust protocol to study CNS infections using a bioluminescence model of African trypanosomiasis, providing real time non-invasive observations which can be further analyzed with optional downstream approaches.

This manuscript describes the use of a bioluminescent strain of African trypanosomes to enable the tracking of late stage infection and demonstrates how in vivo live imaging can be used to visualize infections within the central nervous system in real-time.

Human African trypanosomiasis (HAT) is a multi-stage disease that manifests in two stages; an early blood stage and a late stage when the parasite invades ...

Analysis of Lymphocyte Extravasation Using an In Vitro Model of the Human Blood-brain Barrier

Lymphocyte extravasation into the central nervous system (CNS) is critical for immune surveillance. Disease-related alterations of lymphocyte extravasation might result in pathophysiological changes in the CNS. Thus, investigation of lymphocyte migration into the CNS is important to understand inflammatory CNS diseases and to develop new therapy approaches. Here we present an in vitro model of the human blood-brain barrier to study lymphocyte extravasation. Human brain microvascular endothelial cells (HBMEC) are confluently grown on a porous polyethylene terephthalate transwell insert to mimic the endothelium of the blood-brain barrier. Barrier function is validated by zonula occludens immunohistochemistry, transendothelial electrical resistance (TEER) measurements as well as analysis of evans blue permeation. This model allows investigation of the diapedesis of rare lymphocyte subsets such as CD56brightCD16dim/- NK cells. Furthermore, the effects of other cells, cytokines and chemokines, disease-related alterations, and distinct treatment regimens on the migratory capacity of lymphocytes can be studied. Finally, the impact of inflammatory stimuli as well as different treatment regimens on the endothelial barrier can be analyzed.

Analysis of Lymphocyte Extravasation Using an In Vitro Model of the Human Blood-brain Barrier

Here, we describe a human blood-brain barrier model enabling to investigate lymphocyte transmigration into the central nervous system in vitro.

Lymphocyte extravasation into the central nervous system (CNS) is critical for immune surveillance. Disease-related alterations of lymphocyte ...

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 ...

Screening Assays to Characterize Novel Endothelial Regulators Involved in the Inflammatory Response

The endothelial layer is essential for maintaining homeostasis in the body by controlling many different functions. Regulation of the inflammatory response by the endothelial layer is crucial to efficiently fight against harmful inputs and aid in the recovery of damaged areas. When the endothelial cells are exposed to an inflammatory environment, such as the outer component of gram-negative bacteria membrane, lipopolysaccharide (LPS), they express soluble pro-inflammatory cytokines, such as Ccl5, Cxcl1 and Cxcl10, and trigger the activation of circulating leukocytes. In addition, the expression of adhesion molecules E-selectin, VCAM-1 and ICAM-1 on the endothelial surface enables the interaction and adhesion of the activated leukocytes to the endothelial layer, and eventually the extravasation towards the inflamed tissue. In this scenario, the endothelial function must be tightly regulated because excessive or defective activation in the leukocyte recruitment could lead to inflammatory-related disorders. Since many of these disorders do not have an effective treatment, novel strategies with a focus on the vascular layer must be investigated. We propose comprehensive assays that are useful to the search of novel endothelial regulators that modify leukocyte function. We analyze endothelial activation by using specific expression targets involved in leukocyte recruitment (such as, cytokines, chemokines, and adhesion molecules) with several techniques, including: real-time quantitative polymerase chain reaction (RT-qPCR), western-blot, flow cytometry and adhesion assays. These approaches determine endothelial function in the inflammatory context and are very useful to perform screening assays to characterize novel endothelial inflammatory regulators that are potentially valuable for designing new therapeutic strategies.

Vascular endothelium tightly controls leukocyte recruitment. Inadequate leukocyte extravasation contributes to human inflammatory diseases. Therefore, searching for novel regulatory elements of endothelial activation is necessary to design improved therapies for inflammatory disorders. Here, we describe a comprehensive methodology to characterize novel endothelial regulators that can modify leukocyte trafficking during inflammation.

The endothelial layer is essential for maintaining homeostasis in the body by controlling many different functions. Regulation of the inflammatory ...

Quantification of Monocyte Transmigration and Foam Cell Formation from Individuals with Chronic Inflammatory Conditions

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Atherosclerosis, a leading cause of CAD, is initiated by the transmigration of innate immune monocytes to inflammatory sites of deposited lipid called fatty streaks, which are present in arterial walls of medium to large arteries. The key pathogenic feature of lesions at this early stage of atherosclerosis is the maturation of monocytes which migrate into arteries to form foam cells or lipid-laden macrophages. Considerable evidence supports the hypothesis that risk of atherosclerosis is increased by chronic inflammatory conditions accompanying diseases such as rheumatoid arthritis and HIV, as well as general ageing, and that this risk is predicted by monocyte activation. While mouse models provide a good platform to investigate the role of monocytes in atherogenesis in vivo, they require genetic alteration of natural cholesterol metabolism and drastic alteration of normal mouse diets, and have limited suitability for the study of atherogenic influences of human comorbid diseases. This motivated us to develop a human in vitro model to measure the atherogenic potential of monocytes isolated from individuals with defined disease states. Currently, human in vitro models are limiting in that they evaluate monocyte transmigration and foam cell formation in isolation. Here we describe a protocol in which monocytes isolated from patient blood transmigrate across human endothelial cells into a type 1 collagen matrix, and their propensity to mature into foam cells in the presence or absence of exogenous lipid is measured. The protocol has been validated for the use of human monocytes purified from individuals with HIV infection and elderly HIV uninfected individuals. This model is versatile and allows monocyte transmigration and foam cell formation to be evaluated using either microscopy or flow cytometry as well as allowing the assessment of atherogenic factors present in serum or plasma.

We describe a protocol to measure transmigration by monocytes across human endothelial monolayers and their subsequent maturation into foam cells. This provides a versatile method to assess the atherogenic properties of monocytes isolated from people with different disease conditions and to evaluate factors in blood which may enhance this propensity.

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Atherosclerosis, a leading cause of CAD, is initiated by the ...

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins

Stromal interaction molecule-1 (STIM1) is a type-I transmembrane protein located on the endoplasmic reticulum (ER) and plasma membranes (PM). ER-resident STIM1 regulates the activity of PM Orai1 channels in a process known as store operated calcium (Ca2+) entry which is the principal Ca2+ signaling process that drives the immune response. STIM1 undergoes post-translational N-glycosylation at two luminal Asn sites within the Ca2+ sensing domain of the molecule. However, the biochemical, biophysical, and structure biological effects of N-glycosylated STIM1 were poorly understood until recently due to an inability to readily obtain high levels of homogeneous N-glycosylated protein. Here, we describe the implementation of an in vitro chemical approach which attaches glucose moieties to specific protein sites applicable to understanding the underlying effects of N-glycosylation on protein structure and mechanism. Using solution nuclear magnetic resonance spectroscopy we assess both efficiency of the modification as well as the structural consequences of the glucose attachment with a single sample. This approach can readily be adapted to study the myriad glycosylated proteins found in nature.

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins

Biochemical and structural analyses of glycosylated proteins require relatively large amounts of homogeneous samples. Here, we present an efficient chemical method for site-specific glycosylation of recombinant proteins purified from bacteria by targeting reactive Cys thiols.

Stromal interaction molecule-1 (STIM1) is a type-I transmembrane protein located on the endoplasmic reticulum (ER) and plasma membranes (PM). ER-resident ...