Authors were funded in part by the intramural program of NIDCR (N.M.M) and supported by a Wellcome Trust Stepping Stones Fellowship (097820/Z/11/B to J.E.K) and by a Manchester Collaborative Centre for Inflammation Research grant (to J.E.K). The authors thank Teresa Wild for critically reviewing the manuscript.

All experimental procedures described in this protocol followed required guidelines and were approved by the Institutional Animal Care and Use Committee, NIDCR/NIH.
1. Prepare in Advance
<ol>
	<li>Prepare Complete media: RPMI supplemented with 2 mM L-glutamine, 100 units/ml penicillin, 100 ug/ml streptomycin and 10% FBS.</li>
	<li>Prepare DNase media: 50 ml of RPMI media supplemented with 7.5 &#181;g DNase (Make fresh, keep on ice at all times).</li>
	<li>Prepare Collagenase-DNase media: 5 ml of DNase media plus 3.2 mg/ml of Collagenase Type IV (Make fresh, keep on ice at all times).</li>
	<li>Pre-cool FACS buffer: 0.5 % FBS diluted in PBS.</li>
	<li>Pre-cool centrifuge to 4 &#176;C.</li>
	<li>Warm shaker incubator to 37 &#176;C.</li>
</ol>
2. Isolation, Dissection, and Cell Isolation from Gingival Blocks
<ol>
	<li>Euthanize mice by exposing them to CO2 in an appropriate chamber, according to ARAC guidelines.</li>
	<li>Open the thoracic and abdominal cavity to expose the heart and internal organs. To perfuse, make an incision in the inferior vena cava and perfuse 3 ml of PBS via the left ventricle using a 3 ml syringe with a 27 G needle.</li>
	<li>Immobilize the body and head of the mouse on a pad with stomach facing up.</li>
	<li>Cut each commissure of the lip towards the neck with scissors, separating the skin that covers mandible and neck region, exposing the underlying tissues and muscles. Dissect the lower lip to uncover the mandible.</li>
	<li>Cut between the lower incisors to separate both sides of the mandible and immobilize each side to access the oral cavity.</li>
	<li>Visualize and dissect the palate away from the nasal cavity.</li>
	<li>Dissect areas using a 10 blade and include maxillary and mandibular molar areas with surrounding gingiva (Figure 1). Make vertical incisions just anterior to the first molar and posterior to the third molar and a horizontal incision at the border of the gingiva (white collar of tissue surrounding teeth).</li>
	<li>Place the maxillary and mandibular blocks in a 50 ml conical tube with 5 ml Collagenase/DNase (keep on ice).</li>
	<li>Incubate in a shaker incubator at 37 &#176;C for 1 hr and during the last 5 min of incubation add 50 &#181;l of 0.5 M EDTA.</li>
	<li>Add 5 ml of cold DNase media to the 50 ml tube with tissues and gently swirl to mix.</li>
	<li>Transfer the 4 blocks of tissue on a petri dish and cover with 500 &#181;l of DNase media. Remove gingiva from each block of tissue, using a scalpel blade and pointing the blade into the gingival and interdental areas.</li>
	<li>Transfer the tissues and the media from the petri dish as well as the previous DNase media used during dissection, to a new 50 ml tube through the cell strainer (70 &#181;m size). Wash with DNase media (3-5 ml) all of the instruments used and filter.</li>
	<li>Using the plunger of a sterile 3 ml syringe, mash the tissue against the strainer, filtering with cold DNase media (30 to 35 ml).</li>
	<li>Wash the cell strainer with cold DNase media.</li>
	<li>Centrifuge at 4 &#176;C, 314 x g for 6 min.</li>
	<li>Discard the supernatant, re-suspend in 1 ml of complete media.</li>
	<li>Count cells (the expected amount should range between 8 x 105 to 1.2 x 106 cells with a viability of &#62;80%) using an automated cell counter.</li>
</ol>
3. Stimulation and FACS Staining of Gingival Cells
<ol>
	<li>Stimulate the single cell suspension with PMA (50 ng/ml) and Ionomycin (2.5 &#181;g/ml) in the presence of 1 &#181;l/ml of Brefeldin A.</li>
	<li>Incubate for 3.5 hr at 37 &#176;C and 5% CO2.</li>
	<li>Spin down and wash with PBS and centrifuge at 4 &#176;C; 314 x g for 6 min.</li>
	<li>Stain the cells using a viability stain following the manufacturer&#39;s instructions.</li>
	<li>Stain for extracellular markers (CD45, TCR&#947;&#948;, TCR&#946;, CD4, CD8, TCR&#947;&#948; or antibodies of choice) following the manufacturer&#39;s instructions.</li>
	<li>Wash the cells with cold FACS buffer and centrifuge at 4 &#176;C, 314 x g for 5 min.</li>
	<li>Gently vortex to disrupt the cell pellet.</li>
	<li>Fix the cells with 2% paraformaldehyde for 20 min at room temperature.</li>
	<li>Wash the cells with cold FACS buffer, centrifuge at 4 &#176;C, 314 x g for 5 min and stain for intracellular cytokines.
	<ol>
		<li>Fill the FACS tubes with a solution of cold 0.5% saponin diluted in FACS buffer and centrifuge at 4 &#176;C, 314 x g for 5 min.</li>
		<li>Add 300 &#181;l of 0.5% saponin solution to the FACS tubes, incubate for 15 min in the dark at 4 &#176;C and then centrifuge at 4 &#176;C, 314 x g for 5 min.</li>
		<li>Stain the cells for intracellular markers (IL-17A and IFN&#947; or cytokines of choice) following the manufacturer&#39;s instructions. Wash the cells with 0.5% saponin solution and centrifuge at 4 &#176;C, 314 x g for 5 min.</li>
		<li>Wash again with FACS buffer and centrifuge at 4 &#176;C, 314 x g for 5 min.</li>
		<li>Re-suspend the cells in 300 &#181;l of FACS buffer.</li>
	</ol>
	</li>
	<li>Analyze results on a flow cytometer.</li>
</ol>
4. Flow Cytometry Analysis
<ol>
	<li>Visualize cells to be analyzed on forward (FSC) and side scatter (SCC) and gate to exclude debris.</li>
	<li>Select single cells with forward scatter area (FSC-A) vs. height (FSC-H) parameters.</li>
	<li>Gate cells that are live (as indicated by viability staining) and positive for the hematopoietic marker CD45+ for further analysis (Figure 2A and 2C).</li>
	<li>Continue analysis of specific markers as shown in Figure 2 and Figure 3.</li>
</ol>

<ol>
	<li>Aas, J. A., Paster, B. J., Stokes, L. N., Olsen, I., Dewhirst, F. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Defining+The+Normal+Bacterial+Flora+Of+The+Oral+Cavity.">Defining The Normal Bacterial Flora Of The Oral Cavity.</a> J Clin Microbiol. 43, 5721-5732 (2005).</li><li>Belkaid, Y., Naik, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Compartmentalized+And+Systemic+Control+Of+Tissue+Immunity+By+Commensals.">Compartmentalized And Systemic Control Of Tissue Immunity By Commensals.</a> Nat Immunol. 14, 646-653 (2013).</li><li>Darveau, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Periodontitis:+A+Polymicrobial+Disruption+Of+Host+Homeostasis.">Periodontitis: A Polymicrobial Disruption Of Host Homeostasis.</a> Nat Rev Microbiol. 8, 481-490 (2010).</li><li>Hajishengallis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunomicrobial+Pathogenesis+Of+Periodontitis:+Keystones,+Pathobionts,+And+Host+Response.">Immunomicrobial Pathogenesis Of Periodontitis: Keystones, Pathobionts, And Host Response.</a> Trends Immunol. 35, 3-11 (2014).</li><li>Eke, P. I., 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=Prevalence+Of+Periodontitis+In+Adults+In+The+United+States:+2009+And+2010.">Prevalence Of Periodontitis In Adults In The United States: 2009 And 2010.</a> J Dent Res. 91, 914-920 (2012).</li><li>Moutsopoulos, N. M., Lionakis, M. S., Hajishengallis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inborn+Errors+In+Immunity:+Unique+Natural+Models+To+Dissect+Oral+Immunity.">Inborn Errors In Immunity: Unique Natural Models To Dissect Oral Immunity.</a> J Dent Res. , (2015).</li><li>Hajishengallis, G., Lamont, R. J., Graves, D. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Enduring+Importance+Of+Animal+Modelsin+Understanding+Periodontal+Disease.">The Enduring Importance Of Animal Modelsin Understanding Periodontal Disease.</a> Virulence. 6, 229-235 (2015).</li><li>Sharrow, S. O., Coligan, J. 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=Analysis+Of+Flow+Cytometry+Data.">Analysis Of Flow Cytometry Data.</a> Current Protocols In Immunology. , (2001).</li><li>Arizon, 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=Langerhans+Cells+Down-Regulate+Inflammation-Driven+Alveolar+Bone+Loss.">Langerhans Cells Down-Regulate Inflammation-Driven Alveolar Bone Loss.</a> Proc Natl Acad Sci U S A. 109, 7043-7048 (2012).</li><li>Moutsopoulos, N. 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=Defective+Neutrophil+Recruitment+In+Leukocyte+Adhesion+Deficiency+Type+I+Disease+Causes+Local+IL-17-Driven+Inflammatory+Bone+Loss.">Defective Neutrophil Recruitment In Leukocyte Adhesion Deficiency Type I Disease Causes Local IL-17-Driven Inflammatory Bone Loss.</a> Sci Transl Med. 6, 229-240 (2014).</li><li>Gaffen, S. L., Jain, R., Garg, A. V., Cua, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+IL-23-IL-17+Immune+Axis:+From+Mechanisms+To+Therapeutic+Testing.">The IL-23-IL-17 Immune Axis: From Mechanisms To Therapeutic Testing.</a> Nat Rev Immunol. 14, 585-600 (2014).</li></ol>

Authors have nothing to disclose

The current technique successfully yields a large number of immune cells (from a single mouse) suitable, not only for phenotypic characterization, but also for functional studies ex vivo. Another group had previously published a protocol to isolate and characterize murine gingival immune cells and introduced the value of using multicolor flow cytometry in the study of periodontitis in animal models 9. Following considerable troubleshooting the key modification in this protocol was to include dissection of whole blocks of tissue in order to include both gingival collar areas and interdental gingiva (Figure 1). With gingival dissection alone, often full thickness flaps are not achieved and part of the gingiva is missed particularly in the interdental areas. Using this approach, numbers of immune cells harvested are significantly increased. This technique also allows for optimal isolation of gingival tissues both from maxilla and mandible.
Critical steps for this protocol include a conservative dissection of gingival areas and an efficient rate of dissection. Specifically, blocks of tissue should be dissected to include only minimal tissue around teeth (gingiva) and not buccal tissues. Blocks should be dissected quickly and tissues and cells should remain on ice to ensure optimal cell viability.
For purposes of troubleshooting it is important to note that low yield of cells can be related to inadequate time of incubation with collagenase, inappropriate concentrations of collagenase and/or inadequate dissection of the gingiva from the tissue blocks. On that note, dissection of gingiva using magnifying loupes (2X-6X) can be helpful. Low viability of cells can be related to tardiness in the procedure and to media, buffers and cells not remaining continuously on ice.
Limitations of this protocol, inherent to the type of tissue dissected is the size of the gingival tissues, compared to other anatomical barrier sites studied (ex. Skin or gastrointestinal tract) in which larger tissues are available.
Nonetheless, the technique presented here has allowed us to characterize the dominant cell populations in the LFA-/- model which spontaneously developed periodontitis. In LFA-/- mice we identified a dominant IL-17 cytokine signature during the development of periodontitis 10. Using multicolor flow cytometric analysis we were able to define the cellular sources of IL-17 11. In this disease setting IL-17 was produced by TCR&#947;&#948; T cells, CD4+ T cells and innate lymphoid cells (ILC) locally within the gingiva 10.
With the substantial number of cells isolated with this methodology and the ability to identify even small subpopulations, it will now be possible to develop a comprehensive understanding of the specialized immune cell network safeguarding gingival barrier integrity. This critical insight will allow us to evaluate immune responses in the gingival environment. By employing this technique we can now proceed to isolate specific constituents of the gingiva immune cell network by flow cytometric cell sorting, allowing additional analyses and characterizations to be undertaken.

Gingival tissues surround the human and murine dentition and are constantly exposed to the complex biofilm of the tooth 1. The immune cell network policing the gingival barrier is vital to maintaining tissue integrity, ensuring homeostasis with the local commensal microbes and, at the same time, providing effective immunity against pathogenic challenge 2. To achieve homeostasis, the immune system is carefully tailored to the gingival environment creating a highly-specialized immune cell network, yet little detail is known of the gingival immune cell populations and their role in maintaining tissue immunity 2.
When immune homeostasis is disrupted at the gingiva, either through increased host susceptibility and/or presence of dysbiotic microbial communities, an inflammatory condition, periodontitis arises 34. Periodontitis is a common inflammatory disease, leading to loss of tooth supporting structures. In its severe forms it is seen in approximately 10% of the general population 5. Dissecting the key factors involved in periodontitis susceptibility and progression has proven difficult 6. However, animal models have been extremely useful in understanding the mechanisms of periodontitis initiation and progression 7. Models can be employed to define the key cell populations and molecular mediators that are vital for maintaining immune homeostasis and drive development of periodontitis. Such insight will transform our understanding of gingiva-specific control of immune homeostasis and further our current understanding of disease pathogenesis.

<table><tbody><tr><td>Fine Scissors</td><td>Fine science tools</td><td>14058-11</td><td></td></tr><tr><td>Scalpel Handle #3</td><td>Fine science tools</td><td>10003-12</td><td></td></tr><tr><td>Scalpel Blades #10</td><td>Fine science tools</td><td>10010-00</td><td>Sterile</td></tr><tr><td>Splinter Forceps</td><td>Integra Miltex</td><td>6-304</td><td></td></tr><tr><td>Needles with regular bevel&amp;nbsp;</td><td>BD Medical</td><td>305109</td><td>27 G, 12.7 mm length</td></tr><tr><td>Monoject syringes</td><td>Covidien</td><td>8881513934</td><td>Luer-lock tip, 3 ml</td></tr><tr><td>PBS, pH 7.4</td><td>Life Technologies</td><td>10010-049</td><td>Without Calcium and Magnesium</td></tr><tr><td>RPMI 1640</td><td>Lonza</td><td>12-167F</td><td>Without L-glutamine</td></tr><tr><td>DNase I from bovine pancreas</td><td>Sigma-Aldrich</td><td>DN25-1G</td><td></td></tr><tr><td>Collagenase type IV</td><td>Gibco (by Life technologies)</td><td>17104-019</td><td></td></tr><tr><td>Fetal Bovine Serum</td><td>Gemini Bio-products</td><td>100-106</td><td></td></tr><tr><td>Gentamicin 50 mg/ml</td><td>Quality biological</td><td>120-098-661EA</td><td></td></tr><tr><td>Pen Strep</td><td>Gibco (by Life technologies)</td><td>15140-122</td><td></td></tr><tr><td>L-Glutamine</td><td>Gibco (by Life technologies)</td><td>25030-081</td><td></td></tr><tr><td>0.5 M EDTA pH 8.0</td><td>Quality biological</td><td>351-027-721EA</td><td></td></tr><tr><td>50 ml tubes</td><td>Corning</td><td>352070</td><td>Polypropylene, sterile</td></tr><tr><td>70 &amp;mu;M Cell Strainers</td><td>Corning</td><td>352350</td><td></td></tr><tr><td>Petri dishes</td><td>Corning</td><td>351029</td><td>Sterile</td></tr><tr><td>5 ml FACS tubes</td><td>Corning</td><td>352052</td><td>Sterile</td></tr><tr><td>BD GolgiPlug</td><td>BD Biosciences</td><td>555029</td><td>Contains brefeldin A solution</td></tr><tr><td>Phorbol 12-Myristate 13-Acetate (PMA)</td><td>Sigma-Aldrich</td><td>P8139</td><td></td></tr><tr><td>Ionomycin Calcium Salt</td><td>Sigma-Aldrich</td><td>13909</td><td></td></tr><tr><td>Saponin from quillaja bark</td><td>Sigma-Aldrich</td><td>S4521</td><td></td></tr><tr><td>LIVE/DEAD Fixable Aqua Dead Cell Stain Kit</td><td>Life Technologies</td><td>L34957</td><td></td></tr><tr><td>Anti-Mouse CD45 Alexa Fluor 700</td><td>eBioscience</td><td>56-0451-82</td><td></td></tr><tr><td>Anti-Mouse CD4 eFluor 450</td><td>eBioscience</td><td>48-0042-82</td><td></td></tr><tr><td>Anti-Mouse TCR beta APC eFluor 780</td><td>eBioscience</td><td>47-5961-82</td><td></td></tr><tr><td>Anti-Mouse gamma delta TCR FITC</td><td>eBioscience</td><td>11-5711-82</td><td></td></tr><tr><td>Anti-Mouse IL-17A APC</td><td>eBioscience</td><td>12-7311-82</td><td></td></tr><tr><td>Anti-Mouse IFN-&amp;gamma; PE</td><td>eBioscience</td><td>11-5931-82</td><td></td></tr><tr><td>Anti-Mouse NK1.1 PE-Cy7</td><td>eBioscience</td><td>25-5941-82</td><td></td></tr><tr><td>Anti-Mouse CD90.2 APC eFluor 780</td><td>eBioscience</td><td>47-0902-82</td><td></td></tr><tr><td>Anti-Mouse CD3e FITC</td><td>eBioscience</td><td>11-0031-82</td><td></td></tr><tr><td>Anti-Mouse CD19 FITC</td><td>eBioscience</td><td>11-0193-82</td><td></td></tr><tr><td>Anti-Mouse CD11b FITC</td><td>eBioscience</td><td>11-0112-82</td><td></td></tr><tr><td>Anti-Mouse CD11c FITC</td><td>eBioscience</td><td>11-0114-82</td><td></td></tr><tr><td>Anti-Mouse TCR beta FITC</td><td>eBioscience</td><td>11-5961-82</td><td></td></tr><tr><td>Anti-Mouse Ly-6G FITC</td><td>eBioscience</td><td>11-5931-82</td><td></td></tr><tr><td>Anti-Mouse Ly-6C FITC</td><td>BD Pharmingen</td><td>553104</td><td></td></tr></tbody></table>

isolation, characterization and functional examination of the gingival immune cell network

Immune cell networks in tissues play a vital role in mediating local immunity and maintaining tissue homeostasis, yet little is known of the resident immune cell populations in the oral mucosa and gingiva. We have established a technique for the isolation and study of immune cells from murine gingival tissues, an area of constant microbial exposure and a vulnerable site to a common inflammatory disease, periodontitis. Our protocol allows for a detailed phenotypic characterization of the immune cell populations resident in the gingiva, even at steady state. Our procedure also yields sufficient cells with high viability for use in functional studies, such as the assessment of cytokine secretion ex vivo. This combination of phenotypic and functional characterization of the gingival immune cell network should aid towards investigating the mechanisms involved in oral immunity and periodontal homeostasis, but will also advance our understanding of the mechanisms involved in local immunopathology.

To illustrate application of the protocol, we show representative results examining the immune cell network in the gingiva of mice with and without periodontitis (WT vs. LFA-/-, Figure 2A-C). Representative FACS plots show live CD45+ hematopoietic cells in the gingiva (Figure 2A, 2C). Isolation and processing of immune cells with this protocol yields sufficient cells to perform ex vivo stimulation and characterization of cytokine secretion patterns. Here we show IL-17 and IFN-&#947; staining in total CD45+ cells in the steady state (WT) and in mice exhibiting periodontitis (due to LFA deficiency) (Figure 2B-D). These data reveal the potential of this technique to capture cytokine profiles during tissue steady state (WT) and in the context of local periodontitis (LFA-/-). In mice susceptible to periodontitis we further characterized the gingival immune cell composition particularly of the T cell and Innate Lymphoid cell (ILC) compartments (Figure 3A-B). We were able to define the production of IL-17 and IFN-&#947; within the TCR&#946;+CD4+ T cell, TCR&#946;+CD8+ T cell, TCR&#947;&#948;+ T cell, NK and ILC compartments (Figure 3C).
<img alt="Figure 1" src="/files/ftp_upload/53736/53736fig1.jpg" /> 
Figure 1: Isolation of murine gingiva.&#160;Illustration demonstrating the boarders of dissection in the maxilla and the isolated gingival segment to be used for gingival tissue dissection. (B) Segment of murine maxilla (molar area) with outline for block dissection and isolated block. Hematoxylin and Eosin stain (H&#38;E) of a maxillary molar segment with gingival tissues outlined is shown in low (C) and higher magnification in (D). Original magnifications indicated. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/53736/53736fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" src="/files/ftp_upload/53736/53736fig2.jpg" /> 
Figure 2: Representative FACS data for cytokine production from gingival cells.&#160;(A-C) FACS plot showing gate for live CD45+ cells in mouse gingival cell preparations following ex vivo re-stimulation with PMA and ionomycin in WT and LFA-/-. (B-D) Representative FACS plots showing IFN-&#947; and IL-17 staining in total CD45+ cells mouse from gingiva of mice with/without periodontitis (due to LFA-deficiency). <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/53736/53736fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/53736/53736fig3.jpg" /> 
Figure 3: Cytokine production by immune populations in inflamed gingiva.&#160;(A) Representative FACS plot showing staining for TCR&#946; versus TCR&#947;&#948; gated on CD45+ cells. Gating on TCR&#946;+ cells, middle plot shows CD4 versus TCR&#946; staining (allows for analysis of TCR&#946;+CD4+ T cells, TCR&#946;+CD8+ T cells and TCR&#947;&#948;+ T cells). Gating on TCR&#946;- TCR&#947;&#948;- cells, right plot shows CD45 versus NK1.1 staining (allows for analysis of NK cells). (B) Representative FACS plot showing staining for CD90.2 gated on CD45+ lineage negative cells (CD3&#8722;CD19&#8722;NK1.1&#8722;CD11c&#8722;CD11b&#8722;Ly6G&#8722;Ly6C&#8722;TCR&#947;&#948;&#8722;TCR&#946;&#8722;) which identifies innate lymphoid cells. (C) Representative FACS plots showing IFN-&#947; and IL-17 staining in cell populations identified. Gingiva preparations are from 20 week old LFA-/- mice that develop periodontitis; data are representative of three independent experiments. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/53736/53736fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Isolation, Characterization and Functional Examination of the Gingival Immune Cell Network at JoVE.com

Isolation, Characterization and Functional Examination of the Gingival Immune Cell Network

We have established a technique for the isolation, phenotypic characterization and functional analysis of immune cells from murine gingiva.

Immune cell networks in tissues play a vital role in mediating local immunity and maintaining tissue homeostasis, yet little is known of the resident ...

isolation-characterization-functional-examination-gingival-immune

Universidad San Sebastian

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Immunology and Infection

10.8K Views.  NIH. We have established a technique for the isolation, phenotypic characterization and functional analysis of immune cells from murine gingiva.

Video: Isolation, Characterization and Functional Examination of the Gingival Immune Cell Network

Isolating And Immunostaining Lymphocytes and Dendritic Cells from Murine Peyer's Patches

Peyer's patches (PPs) are integral components of the gut-associated lymphoid tissues (GALT) and play a central role in intestinal immunosurveillance and homeostasis. Particulate antigens and microbes in the intestinal lumen are continuously sampled by PP M cells in the follicle-associated epithelium (FAE) and transported to an underlying network of dendritic cells (DCs), macrophages, and lymphocytes. In this article, we describe protocols in which murine PPs are (i) dissociated into single cell suspensions and subjected to flow cytometry and (ii) prepared for cryosectioning and immunostaining. For flow cytometry, PPs are mechanically dissociated and then filtered through 70 &mu;m membranes to generate single cell suspensions free of epithelial cells and large debris. Starting with 20-25 PPs (from four mice), this quick and reproducible method yields a population of &gt;2.5 x 106 cells with &gt;90% cell viability. For cryosectioning, freshly isolated PPs are immersed in Optimal Cutting Temperature (OCT) medium, snap-frozen in liquid nitrogen, and then sectioned using a cryomicrotome. Tissue sections (5-12 &mu;m) are air-dried, fixed with acetone or methanol, and then subjected to immunolabeling.

There is an increasing interest in understanding the immunological functions of specific subpopulations of cells in Peyer's patches (PPs), the primary inductive sites of gut-associated lymphoid tissues. Here we outline parallel protocols for preparing PP single cell preparations for flow cytometric analysis and PP cryosections for immunostaining.

Peyer's  patches (PPs) are integral components of the gut-associated lymphoid tissues  (GALT) and play a central role in intestinal immunosurveillance and ...

Isolation, Processing and Analysis of Murine Gingival Cells

We have developed a technique to precisely isolate and process murine gingival tissue for flow cytometry and molecular studies. The gingiva is a unique and important tissue to study immune mechanisms because it is involved in host immune response against oral biofilm that might cause periodontal diseases. Furthermore, the close proximity of the gingiva to alveolar bone tissue enables also studying bone remodeling under inflammatory conditions. Our method yields large amount of immune cells that allows analysis of even rare cell populations such as Langerhans cells and T regulatory cells as we demonstrated previously 1. Employing mice to study local immune responses involved in alveolar bone loss during periodontal diseases is advantageous because of the availability of various immunological and experimental tools. Nevertheless, due to their small size and the relatively inconvenient access to the murine gingiva, many studies avoided examination of this critical tissue. The method described in this work could facilitate gingival analysis, which hopefully will increase our understating on the oral immune system and its role during periodontal diseases.

This study describes an efficient technique to isolate and process gingival tissues from the mouse oral cavity in order to produce a single-cell culture. The resulting cells can be further used for flow cytometry analysis and molecular studies.

We have developed a technique to precisely isolate and process murine gingival tissue for flow cytometry and molecular studies. The gingiva is a unique ...

Three-dimensional Inflammatory Human Tissue Equivalents of Gingiva

Periodontal diseases (such as gingivitis and periodontitis) are the leading causes of tooth loss in adults. Inflammation in gingiva is the fundamental physiopathology of periodontal diseases. Current experimental models of periodontal diseases have been established in various types of animals. However, the physiopathology of animal models is different from that of humans, making it difficult to analyze cellular and molecular mechanisms and evaluate new medicines for periodontal diseases. Here, we present a detailed protocol for reconstructing human inflammatory tissue equivalents of gingiva (iGTE) in vitro. We first build human tissue equivalents of gingiva (GTE) by utilizing two types of human cells, including human gingival fibroblasts (HGF) and human skin epidermal keratinocytes (HaCaT), under three-dimensional conditions. We create a wound model by using a tissue puncher to punch a hole in the GTE. Next, human THP-1 monocytes mixed with collagen gel are injected into the hole in the GTE. By adimistration of 10 ng/mL phorbol 12-myristate 13-acetate (PMA) for 72 h, THP-1 cells differentiated into macrophages to form inflammatory foci in GTE (iGTE) (IGTE also can be stumilated with 2 &#181;g/mL of lipopolysaccharides (LPS) for 48 h to initiate inflammation). IGTE is the first in vitro model of inflammatory gingiva using human cells with a three-dimensional architecture. IGTE reflects major pathological changes (immunocytes activition, intracellular interactions among fibryoblasts, epithelial cells, monocytes and macrophages) in periodontal diseases. GTE, wounded GTE, and iGTE can be used as versatile tools to study wound healing, tissue regeneration, inflammation, cell-cell interaction, and screen potential medicines for periodontal diseases.

The goal of the protocol is to build an inflammatory human gingiva model in vitro. This tissue model co-cultivates three types of human cells, HaCaT keratinocytes, gingival fibroblasts, and THP-1 macrophages, under three-dimensional conditions. This model can be applied to investigating periodontal diseases, such as gingivitis and periodontitis.

Periodontal diseases (such as gingivitis and periodontitis) are the leading causes of tooth loss in adults. Inflammation in gingiva is the fundamental ...

Developmental Biology

A Mouse Model for Pathogen-induced Chronic Inflammation at Local and Systemic Sites

Chronic inflammation is a major driver of pathological tissue damage and a unifying characteristic of many chronic diseases in humans including neoplastic, autoimmune, and chronic inflammatory diseases. Emerging evidence implicates pathogen-induced chronic inflammation in the development and progression of chronic diseases with a wide variety of clinical manifestations. Due to the complex and multifactorial etiology of chronic disease, designing experiments for proof of causality and the establishment of mechanistic links is nearly impossible in humans. An advantage of using animal models is that both genetic and environmental factors that may influence the course of a particular disease can be controlled. Thus, designing relevant animal models of infection represents a key step in identifying host and pathogen specific mechanisms that contribute to chronic inflammation.
Here we describe a mouse model of pathogen-induced chronic inflammation at local and systemic sites following infection with the oral pathogen Porphyromonas gingivalis, a bacterium closely associated with human periodontal disease. Oral infection of specific-pathogen free mice induces a local inflammatory response resulting in destruction of tooth supporting alveolar bone, a hallmark of periodontal disease. In an established mouse model of atherosclerosis, infection with P. gingivalis accelerates inflammatory plaque deposition within the aortic sinus and innominate artery, accompanied by activation of the vascular endothelium, an increased immune cell infiltrate, and elevated expression of inflammatory mediators within lesions. We detail methodologies for the assessment of inflammation at local and systemic sites. The use of transgenic mice and defined bacterial mutants makes this model particularly suitable for identifying both host and microbial factors involved in the initiation, progression, and outcome of disease. Additionally, the model can be used to screen for novel therapeutic strategies, including vaccination and pharmacological intervention.

Animal models have proven to be invaluable tools in defining host and pathogen specific mechanisms that contribute to the development of chronic inflammation. Here we describe a mouse model of oral infection with the human pathogen Porphyromonas gingivalis and detail methodologies to assess the progression of inflammation at local and systemic sites.

Chronic inflammation is a major driver of pathological tissue damage and a unifying characteristic of many chronic diseases in humans including ...

In Situ Detection of Bacteria within Paraffin-embedded Tissues Using a Digoxin-labeled DNA Probe Targeting 16S rRNA

The presence of bacteria within the pocket epithelium and underlying connective tissue in gingival biopsies from patients with periodontitis has been reported using various methods, including electron microscopy, immunohistochemistry or immunofluorescence using bacteria-specific antibodies, and fluorescent in situ hybridization (FISH) using a fluorescence-labeled oligonucleotide probe. Nevertheless, these methods are not widely used due to technical limitation or difficulties. Here a method to localize bacteria within paraffin-embedded tissues using DIG-labeled DNA probes has been introduced. The paraffin-embedded tissues are the most common form of biopsy tissues available from pathology banks. Bacteria can be detected either in a species-specific or universal manner. Bacterial signals are detected as either discrete forms (coccus, rod, fusiform, and hairy form) of bacteria or dispersed forms. The technique allows other histological information to be obtained: the epithelia, connective tissue, inflammatory infiltrates, and blood vessels are well distinguished. This method can be used to study the role of bacteria in various diseases, such as periodontitis, cancers, and inflammatory immune diseases.

In Situ Detection of Bacteria within Paraffin-embedded Tissues Using a Digoxin-labeled DNA Probe Targeting 16S rRNA

Here a method to localize bacteria within paraffin-embedded tissues using DIG-labeled 16S rRNA-targeting DNA probes has been described. This protocol can be applied to study the role of bacteria in various diseases such as periodontitis, cancers, and inflammatory immune diseases.

The presence of bacteria within the pocket epithelium and underlying connective tissue in gingival biopsies from patients with periodontitis has been ...

Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells

Anaerobic bacteria far outnumber aerobes in many human niches such as the gut, mouth, and vagina. Furthermore, anaerobic infections are common and frequently of indigenous origin. The ability of some anaerobic pathogens to invade human cells gives them adaptive measures to escape innate immunity as well as to modulate host cell behavior. However, ensuring that the anaerobic bacteria are live during experimental investigation of the events may pose challenges. Porphyromonas gingivalis, a Gram-negative anaerobe, is capable of invading a variety of eukaryotic non-phagocytic cells. This article outlines how to successfully culture and assess the ability of P. gingivalis to invade human umbilical vein endothelial cells (HUVECs). Two protocols were developed: one to measure bacteria that can successfully invade and survive within the host, and the other to visualize bacteria interacting with host cells. These techniques necessitate the use of an anaerobic chamber to supply P. gingivalis with an anaerobic environment for optimal growth.
The first protocol is based on the antibiotic protection assay, which is largely used to study the invasion of host cells by bacteria. However, the antibiotic protection assay is limited; only intracellular bacteria that are culturable following antibiotic treatment and host cell lysis are measured. To assess all bacteria interacting with host cells, both live and dead, we developed a protocol that uses fluorescent microscopy to examine host-pathogen interaction. Bacteria are fluorescently labeled with 2&#39;,7&#39;-Bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM) and used to infect eukaryotic cells under anaerobic conditions. Following fixing with paraformaldehyde and permeabilization with 0.2% Triton X-100, host cells are labeled with TRITC phalloidin and DAPI to label the cell cytoskeleton and nucleus, respectively. Multiple images taken at different focal points (Z-stack) are obtained for temporal-spatial visualization of bacteria. Methods used in this study can be applied to any cultivable anaerobe and any eukaryotic cell type.

Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells

This article presents two protocols: one to measure anaerobic bacteria that can successfully invade and survive within the host, and the other to visualize anaerobic bacteria interacting with host cells. This study can be applied to any cultivable anaerobe and any eukaryotic cell type.

Anaerobic bacteria far outnumber aerobes in many human niches such as the gut, mouth, and vagina. Furthermore, anaerobic infections are common and ...

Rapid Isolation of Single Cells from Mouse and Human Teeth

Mouse and human teeth represent challenging organs for quick and efficient cell isolation for single-cell transcriptomic or other applications. The dental pulp tissue, rich in the extracellular matrix, requires a long and tedious dissociation process that is typically beyond the reasonable time for single-cell transcriptomics. For avoiding artificial changes in gene expression, the time elapsed from euthanizing an animal until the analysis of single cells needs to be minimized. This work presents a fast protocol enabling to obtain single-cell suspension from mouse and human teeth in an excellent quality suitable for scRNA-seq (single-cell RNA-sequencing). This protocol is based on accelerated tissue isolation steps, enzymatic digestion, and subsequent preparation of final single-cell suspension. This enables fast and gentle processing of tissues and allows using more animal or human samples for obtaining cell suspensions with high viability and minimal transcriptional changes. It is anticipated that this protocol might guide researchers interested in performing the scRNA-seq not only on the mouse or human teeth but also on other extracellular matrix-rich tissues, including cartilage, dense connective tissue, and dermis.

The current protocol presents a fast, efficient, and gentle method for isolating single cells suitable for single-cell RNA-seq analysis from a continuously growing mouse incisor, mouse molar, and human teeth.

Mouse and human teeth represent challenging organs for quick and efficient cell isolation for single-cell transcriptomic or other applications. The dental ...

Isolation and Culture of Primary Human Gingival Epithelial Cells using Y-27632

The gingival tissue is the first structure that protects periodontal tissues and plays meaningful roles in many oral functions. The gingival epithelium is an important structure of gingival tissue, especially in the repair and regeneration of periodontal tissue. Studying the functions of gingival epithelial cells has crucial scientific value, such as repairing oral defects and detecting the compatibility of biomaterials. As human gingival epithelial cells are highly differentiated keratinized cells, their lifespan is short, and they are difficult to passage. So far, there are only two ways to isolate and culture gingival epithelial cells, a direct explant method and an enzymatic method. However, the time required to obtain epithelial cells using the direct explant method is longer, and the cell survival rate of the enzymatic method is lower. Clinically, the acquisition of gingival tissue is limited, so a stable, efficient, and simple in vitro isolation and culture system is needed. We improved the traditional enzymatic method by adding Y-27632, a Rho-associated kinase (ROCK) inhibitor, which can selectively promote the growth of epithelial cells. Our modified enzymatic method simplifies the steps of the traditional enzymatic method and increases the efficiency of culturing epithelial cells, which has significant advantages over the direct explant method and the enzymatic method.

Here we present a modified method for the isolation and culture of human gingival epithelial cells by adding the Rock inhibitor, Y-27632, to the traditional method. This method is easier, less time-consuming, enhances stem cell properties, and produces larger numbers of high-potential epithelial cells both for the laboratory and for clinical applications.

The gingival tissue is the first structure that protects periodontal tissues and plays meaningful roles in many oral functions. The gingival epithelium is ...

Bioengineering

Isolation of Tonsillar Mononuclear Cells to Study Ex Vivo Innate Immune Responses in a Human Mucosal Lymphoid Tissue

Studying isolated cells from mucosa-associated lymphoid tissues (MALT) allows understanding of immune cells response in pathologies involving mucosal immunity, because they can model host-pathogen interactions in the tissue. While isolated cells derived from tissues were the first cell culture model, their use has been neglected because tissue can be hard to obtain. In the present protocol, we explain how to easily process and culture tonsillar mononuclear cells (TMCs) from healthy human tonsils to study innate immune responses upon activation, mimicking viral infection in mucosal tissues. Isolation of TMCs from the tonsils is quick, because the tonsils barely have any epithelium and yield up to billions of all major immune cell types. This method allows detection of cytokine production using several techniques, including immunoassays, qPCR, microscopy, flow cytometry, etc., similar to the use of peripheral mononuclear cells (PBMCs) from blood. Furthermore, TMCs show a higher sensitivity to drug testing than PBMCs, which needs to be considered for future toxicity assays. Thus, ex vivo TMCs cultures are an easy and accessible mucosal model.

In the present protocol, we explain how to easily process and culture tonsillar mononuclear cells from healthy humans undergoing partial surgical tonsillectomy to study innate immune responses upon activation, mimicking viral infection in mucosal tissues.

Studying isolated cells from mucosa-associated lymphoid tissues (MALT) allows understanding of immune cells response in pathologies involving mucosal ...

Organotypic Tissue Model Systems for Investigating Host-Pathogen Interactions In Vitro

Recapitulating the host-pathogen interface at the epithelial or mucosal barrier in vitro remains a challenging prospect for infection biologists. While in-house grown 2D epithelial monolayers lack true representation of the in vivo situation, commercially available tissue models are often overlooked due to their cost and practicality. However, with careful planning, such models provide reproducible platforms for a vast array of different applications. Here, we report the use of epithelial models that can be utilized for a wide variety of experimental purposes to investigate host-pathogen interactions in various ecological niches, such as the oral cavity, skin, and vaginal mucosa. From simple planktonic cells to complex biofilm co-culture, epithelial models are used to assess microbial adherence and invasion, and to evaluate the host response at a transcriptional and/or protein level, with scope for more detailed profiling using different omics approaches. Furthermore, these biological systems can be used as more accurate test beds for evaluating conventional and novel antimicrobial activity in a complex host-pathogen microenvironment in vitro. The protocols described herein document how models are handled upon arrival and prepared in the laboratory for co-culture stimulation with biofilm communities. The methods detail how experimental outputs are achieved from the model systems, including the processing of tissue, the co-culture setup, and data generation. These experiments include host gene expression through single- and multiplex qPCR analyses and inflammatory protein detection using ELISAs. In conclusion, epithelial models provide useful in vitro systems for preclinical investigatory studies into simple or complex host-pathogen interactions.

The present protocol outlines the application of organotypic tissue models for investigating host-pathogen interactions in vitro. Specifically, the model system described uses a multi-layered oral epithelium exposed to microorganisms associated with biofilms (dental plaque) within the context of oral health versus disease.

Recapitulating the host-pathogen interface at the epithelial or mucosal barrier in vitro remains a challenging prospect for infection biologists. While ...

Isolation, Characterization and Functional Examination of the Gingival Immune Cell Network

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Isolating And Immunostaining Lymphocytes and Dendritic Cells from Murine Peyer's Patches

Isolation, Processing and Analysis of Murine Gingival Cells

Three-dimensional Inflammatory Human Tissue Equivalents of Gingiva

A Mouse Model for Pathogen-induced Chronic Inflammation at Local and Systemic Sites

In Situ Detection of Bacteria within Paraffin-embedded Tissues Using a Digoxin-labeled DNA Probe Targeting 16S rRNA

Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells

Rapid Isolation of Single Cells from Mouse and Human Teeth

Isolation and Culture of Primary Human Gingival Epithelial Cells using Y-27632

Isolation of Tonsillar Mononuclear Cells to Study Ex Vivo Innate Immune Responses in a Human Mucosal Lymphoid Tissue

Organotypic Tissue Model Systems for Investigating Host-Pathogen Interactions In Vitro