J. W. C. is supported by the Canadian Institutes of Health Research (CIHR). The authors would like to thank Dr. Chunxiang Sun for her assistance in performing the trypan blue staining.

All murine studies complied with the relevant ethical regulations and were approved by the University of Toronto Animal Care Committee and the Research Ethics Board (Protocol 20011930).
1. Ligature installation
NOTE: This is a non-sterile surgical procedure that can be carried out in a standard operating theater. The use of germ-free animals (not covered here) mandates handling within a biosafety cabinet, use of sterile instruments, and inoculation of the oral cavity with periodontal pathogens to cause the clinical manifestations of periodontitis.
<ol>
	<li>Administer intraperitoneal anesthesia to 8&#8211;12 week-old male C57BL/6 mice, which should be acclimated to their housing facility, using a 0.5&#34; 26 G sterile hypodermic needle and 1 mL syringe according to approved institutional animal care and use committee (IACUC) guidelines. 
	NOTE: A combination of ketamine (100 mg/kg) and xylazine (10 mg/kg) anesthetics rapidly and reliably induces the appropriate level of anesthesia for the duration of the procedure.</li>
	<li>Assess the anesthetic depth prior to and every 15 min during the procedure as evidenced by loss of the pedal reflex.</li>
	<li>Position the mouse on a heated surgical platform (Figure 1A). Stabilize the maxilla and mandible in the open position using elastic bands and prop the neck with a cotton roll to help maintain the maxilla in a more horizontal orientation (Figure 1B). Cover the body and tail of the animal to mitigate heat loss during the procedure.</li>
	<li>Position the surgical microscope at the desired magnification and lighting (if not mounted directly to the microscope) over the oral cavity for visualization of the dentition. While the desired magnification is operator-dependent, optimal visualization of the oral cavity is obtained at 16x.</li>
	<li>Install a sterile 5-0 braided silk suture around the first (M1) and second (M2) maxillary molars within the gingival sulcus using splinter forceps. 
	NOTE: Braided silk sutures of a smaller gauge can be used for this purpose to facilitate faster installation and reduce the possibility of iatrogenic soft tissue damage.
	<ol>
		<li>Position the distal tail of the suture on the palatal side of the dentition and insert the proximal segment between the contact of M2 and M3 (Figure 2A).</li>
		<li>Wrap the suture around the buccal surface of M2 and insert it between the contact of M1 and M2. Ensure that both ends of the suture are pulled tightly to drive the suture into the gingival sulcus and remove all slack (Figure 2B).</li>
		<li>Wrap the proximal suture segment around M1, below its height of contour, and insert it between the contact of M1 and M2. Pull the proximal tail of the suture tightly to drive the suture into the gingival sulcus and remove all slack (Figure 2C). 
		NOTE: If resistance is observed when inserting the suture between M1 and M2 or M2 and M3, the contact may be open slightly using a standard dental explorer.</li>
		<li>Tie the ends of the suture with a surgeon&#39;s knot and trim the tails as short as possible. Place the knot in the gingival embrasure between M1 and M2 on the palatal side of the maxillary dentition (Figure 2D). 
		NOTE: Steps 1.4.1&#8211;1.4.4 can be repeated on the contralateral side, if required.</li>
		<li>Sterilize the surgical instruments in a hot glass bead sterilizer between each animal subject. 
		CAUTION: The tips of the forceps are extremely sharp and can easily cause oral trauma and significant bleeding. Prepare small segments of gauze to remove blood from the oral cavity and apply pressure to actively bleeding wounds.</li>
	</ol>
	</li>
	<li>After the ligature installation, remove the mouse from the surgical apparatus, place into a clean cage under a heat lamp and monitor until fully recovered.</li>
	<li>Individually house each mouse with the appropriate environmental enrichment and allow ad libitum access to filtered water and mashed standard chow in a temperature- and humidity-controlled environment (12-h light/12-h dark cycle) for 7&#8211;11 days. 
	NOTE: Mashed chow decreases the forces required for mastication thereby reducing pain associated with feeding, and aids in preventing premature loss of the installed ligature.</li>
</ol>
2. Sample collection
<ol>
	<li>Euthanize mice according to the approved IACUC guidelines. 
	NOTE: Individual euthanasia using a CO2 chamber followed by cervical dislocation is the preferred method for this protocol. This may be altered depending on experiments that require harvesting of additional tissues.</li>
	<li>Using a pipette, immediately rinse the oral cavity with 100 &#181;L of sterilized 4 &#176;C 1x phosphate-buffered saline (PBS) without calcium and magnesium for 10 s.</li>
	<li>Repeat step 2.2 2x and place each rinse in a single 15 mL conical polypropylene sterile test tube.</li>
	<li>Transfer contents to a 50 mL conical polypropylene sterile test tube by running them through a 40 &#956;m nylon mesh filter.</li>
	<li>Transfer these contents into a new 15 mL conical polypropylene sterile test tube. 
	NOTE: The final transfer of the sample to a smaller tube allows for the improved visualization of the cellular pellet in the upcoming steps.
	<ol>
		<li>If desired, remove the molar ligature(s) and place into 300 &#181;L of sterilized 1x PBS (4 &#176;C, without calcium and magnesium) in a separate 15 mL conical polypropylene sterile test tube. Agitate gently and remove the suture from the tube. This sample is treated identically to the oral rinse sample from this point forward.</li>
	</ol>
	</li>
	<li>Add 33.3 &#181;L of 16% paraformaldehyde (PFA) to facilitate the sample fixation.</li>
	<li>Vortex the samples immediately and incubate on ice for 15 min.</li>
	<li>Fill the tube to 15 mL with 1x PBS to dilute PFA, then centrifuge at 1000 x g and 4 &#176;C for 5 min.</li>
	<li>Aspirate the supernatant and resuspend the pellet in 1 mL of fluorescence-activated cell sorting (FACS) buffer at 4 &#176;C. Count cells on a hemocytometer or automated cell counter.</li>
	<li>Centrifuge the sample again at 1000 RCF and 4 &#176;C for 5 min.</li>
	<li>Aspirate the supernatant and resuspend the pellet in an appropriate volume of FACS buffer for a final concentration of 0.5&#8211;1.0 x 106 cells/50 &#956;L of FACS buffer.</li>
</ol>
3. Antibody staining for flow cytometric analysis
NOTE: Label and chill all required FACS tubes prior to use.
<ol>
	<li>Add 1 &#956;L of rat serum and 2 &#956;L of anti-mouse IgG antibody to 50 &#956;L of the sample, vortex immediately, and block on ice for 20 min.</li>
	<li>Add the appropriate antibodies to each sample, vortex immediately, and incubate on ice for 30 min in the dark. 
	NOTE: Selection and volumes of antibodies depend on prior optimization pilot experiments tailored to this specific technique.</li>
	<li>Wash samples with 1 mL of FACS buffer, vortexing briefly and centrifuging for 5 min at 1000 x g and 4 &#176;C. Repeat this step 2x.</li>
	<li>Resuspend samples in 250 &#956;L of FACS buffer, cover tubes with paraffin film, wrap in aluminum foil, and hold at 4 &#176;C until analysis. 
	NOTE: It is ideal to analyze samples within hours of completing the protocol due to the loss of fluorescent signal during long periods of storage. However, samples may be analyzed 2&#8211;3 days later if absolutely required.</li>
</ol>

The authors have nothing to disclose.

The most critical element associated with use of the murine ligature-induced model of periodontitis is centered around the retention of the ligature until the time of sacrifice or intentional removal. The installed biofilm-retentive ligature is capable of inducing a significant loss of alveolar bone height in as few as 6 days, plateauing between the 11&#8211;16 day period39. The decision to sacrifice animal subjects before the maximal period of bone loss, rendering this a much shorter model of lig...

Periodontal disease (PD) is an osteolytic condition associated with significant host morbidity and economic burden, which is manifested by gingival inflammation and loss of both soft tissue attachment and osseous support for the affected dentition1,2,3,4. This process is governed by interactions between the oral microbiota and innate immune system of the host. It is also associated with exacerbation of other systemic inflammatory diseases including diabetes, cardiovascular disease, and cancer5,6,7,8. Historically, it was hypothesized that PD pathogenesis is dependent on large quantities of specific bacteria such as Porphyromonas gingivalis9. However, recent evidence suggests that the microbial component of PD is mediated by the dental biofilm. The biofilm is an organized, complex community of numerous microorganisms that can exist in healthy symbiotic and destructive dysbiotic states10,11. The oral biofilm normally affords resistance to the host by preventing the establishment of foci of pathogenic bacteria and promotes ideal gingival tissue structure and function through regulation of the host immune response12,13. Perturbations of the equilibrious relationship between commensal organisms within the oral cavity and the host immune system may lead to alterations in tissue homeostasis, resulting in dysbacteriosis and development of the hallmark clinical and radiographic appearances of PD5,10,12,13,14.
Interestingly, the establishment of an oral dysbacteriosis, while required for the initiation of PD, is not sufficient to drive PD in all individuals, eluding toward the ability of the host immune response to subvert the transition of microbiota between symbiotic and dysbiotic states15. This places a particular spotlight on the means through which PD influences one of the leading characters of the innate immune system, namely the polymorphonuclear granulocyte (PMN), or neutrophil, from local and systemic perspectives16,17.
In humans, PMNs are recruited from the circulation at a rate of ~2 x 106 cells/h in healthy periodontal connective tissues, where they are the predominating leukocyte population. Here, they are subsequently expelled from the gingival sulcus into the oral cavity as a component of the gingival crevicular fluid. In the presence of PD, neutrophilia manifests within the circulation and oral cavity, where these effector cells possess a hyperinflammatory phenotype that leads to the aforementioned destruction of the periodontium17,18,19,20,21,22. Therefore, understanding the role of PMNs in PD and other systemic inflammatory conditions is of utmost importance.
Although it is widely accepted that chronic diseases are reciprocally linked to PD, the underlying mechanisms have yet to be elucidated, contributing to difficulties in the management of these morbid and potentially fatal systemic conditions. Multiple experimental animal models, each with unique advantages and disadvantages, have been utilized to study the pathophysiology of PD23,24. Focusing specifically on murine models, there are a variety of protocols through which the study of PD is facilitated; however, they possess several technical and physiologic shortcomings25,26,27,28,29,30,31.
First, the oral gavage mouse model requires numerous oral inoculations of human periodontal pathogens to generate gingival inflammation and bone loss. Additionally, it is generally preceded by a period of antibiotic treatment to subvert the murine commensal oral flora25. This model often requires specialized training to safely perform the oral gavage, uses only a small fraction of periodontal pathogens from the more complex human oral microbiome, and requires several months to establish alveolar bone loss.
In contrast, chemically induced murine models utilize the oral delivery of trinitrobenzene sulfonic acid (TNBS) or dextran sulfate sodium (DSS), agents commonly used in establishing murine models of colitis over a period of several months to induce periodontal bone loss26. Intraoral and extraoral abscess-based models are available, which involve the murine incisors and tissues of the dorsum as well as calvarium, respectively. In the former abscess model, several injections of bacteria are administered, creating multiple gingival abscesses and a dearth of alveolar bone loss, limiting their use in the study of PD. The latter abscess models are significantly more apt to studying bacterial virulence, inflammation, and bone resorption at sites outside of the oral cavity, which eliminates evaluation of the periodontium and oral microbiome27,28,29,30,31.
Using the ligature-induced model of periodontitis, a braided silk suture has commonly been installed circumferentially around the second molar. As an alternative, a single linear segment of suture material can be inserted between the first and second molars32,33. The goal of the ligature placement is to facilitate bacterial accumulation and generate dysbiosis within the gingival sulci, resulting in periodontal tissue inflammation and destruction of the tissues composing the periodontium. Most notably, this model is capable of producing significantly more alveolar bone loss compared to the more commonly used oral gavage model34. Further complicating the use of the oral gavage model is the natural resistance by several strains of mice (i.e., C57BL/6) to developing alveolar bone loss. This is also problematic, as this strain is the most frequently used in murine-based animal research35.
Existing procedures described by Marchesan et al. and Abe and Hajishengallis were devised to simplify the technical act of placing the ligature33,36. Unfortunately, the former protocol requires specialized 3D-printed equipment and possess the potential for premature ligature loss, thereby increasing animal use and the costs associated with additional time spent in the operating room. Furthermore, both protocols generate only small regions of the diseased periodontium available for a study.
The advantages that lie with this technique are grounded in the simultaneous study of oral dysbiosis and immunology that govern the periodontium, utilization of low-cost animals with diverse genetic backgrounds, and simple housing and husbandry practices. As such, goals should be to maximize volumes of diseased tissue and, in attempts to practice the principles of reduction in animal research, reduce animal consumption to a level as low as possible. This requires ensuring that all animals are capable of being included in experimental analyses37. However, it should be noted that no matter which animal model of periodontal disease is utilized, there is no single model that encompasses every element of human PD pathophysiology.
This new protocol employs the placement of a ligature around multiple maxillary molar teeth using instrumentation and materials that are found within most laboratories. It allows a sufficient amount of time to easily and confidently install a ligature that is unlikely to avulse prematurely. Finally, as PMNs coordinate destruction of the periodontium in PD, a novel methodology to recover oral neutrophils in a manner analogous to humans is also presented.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Anti-mouse F4/80 Antibody</td>
			<td>BioLegend</td>
			<td>123131</td>
			<td>BV421, Clone BM8</td>
		</tr>
		<tr>
			<td>Anti-mouse Ly6G Antibody</td>
			<td>BD</td>
			<td>560602</td>
			<td>PerCP-Cy5.5, Clone 1A8</td>
		</tr>
		<tr>
			<td>C57BL/6 Male Mice</td>
			<td>Charles River</td>
			<td></td>
			<td>8 to 12 weeks old</td>
		</tr>
		<tr>
			<td>Conical Centrifuge Tube</td>
			<td>FroggaBio</td>
			<td>TB15-500</td>
			<td>15 mL</td>
		</tr>
		<tr>
			<td>Conical Centrifuge Tube</td>
			<td>FroggaBio</td>
			<td>TB50-500</td>
			<td>50 mL</td>
		</tr>
		<tr>
			<td>FACS Buffer</td>
			<td>Multiple</td>
			<td></td>
			<td>1% BSA (BioShop), 2mM EDTA (Merck), 1x HBSS-/- (Gibco)</td>
		</tr>
		<tr>
			<td>FACSDiva</td>
			<td>BD</td>
			<td></td>
			<td>v8.0.1</td>
		</tr>
		<tr>
			<td>Fibre-Lite</td>
			<td>Dolan-Jenner</td>
			<td></td>
			<td>Model 180</td>
		</tr>
		<tr>
			<td>FlowJo</td>
			<td>Tree Star</td>
			<td></td>
			<td>v10.0.8r1</td>
		</tr>
		<tr>
			<td>Heat Therapy Pump</td>
			<td>Hallowell</td>
			<td></td>
			<td>HTP-1500</td>
		</tr>
		<tr>
			<td>Hot Glass Bead Sterilizer</td>
			<td>Electron Microscopy Sciences</td>
			<td>66118-10</td>
			<td>Germinator 500</td>
		</tr>
		<tr>
			<td>Iris Scissors</td>
			<td>Almedic</td>
			<td>7602-A8-684</td>
			<td>Straight</td>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Vetoquinol</td>
			<td></td>
			<td>100mg/mL</td>
		</tr>
		<tr>
			<td>LSRFortessa</td>
			<td>BD</td>
			<td></td>
			<td>X-20</td>
		</tr>
		<tr>
			<td>Mouse Serum</td>
			<td>Sigma</td>
			<td>M5905-5ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Nylon Mesh Filter</td>
			<td>Fisher Scientific</td>
			<td>22-363-547</td>
			<td>40 &#181;m</td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Fisher Scientific</td>
			<td>28908</td>
			<td>16% (w/v), Methanol Free</td>
		</tr>
		<tr>
			<td>Phosphate-buffered Saline</td>
			<td>Sigma</td>
			<td>D1408-500ML</td>
			<td>Without CaCl2 and MgCl2, 10x</td>
		</tr>
		<tr>
			<td>Plastic Disposable Syringes</td>
			<td>BD</td>
			<td>309659</td>
			<td>1 mL</td>
		</tr>
		<tr>
			<td>Rat Serum</td>
			<td>Sigma</td>
			<td>R9759-5ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Silk Suture</td>
			<td>Covidien</td>
			<td>SS652</td>
			<td>C13 USP 5-0</td>
		</tr>
		<tr>
			<td>Splinter Forceps</td>
			<td>Almedic</td>
			<td>7726-A10-700</td>
			<td>#1</td>
		</tr>
		<tr>
			<td>Splinter Forceps</td>
			<td>Almedic</td>
			<td>7727-A10-704</td>
			<td>#5</td>
		</tr>
		<tr>
			<td>Stereo Dissecting Microscope</td>
			<td>Carl Zeiss</td>
			<td>28865</td>
			<td>Photo-Zusatz</td>
		</tr>
		<tr>
			<td>Sterile Hypodemic Needle</td>
			<td>BD</td>
			<td>305111</td>
			<td>26G X 1/2&#34;</td>
		</tr>
		<tr>
			<td>Syringe</td>
			<td>BD</td>
			<td>309659</td>
			<td>1 mL</td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>Rompun</td>
			<td></td>
			<td>20mg/mL</td>
		</tr>
	</tbody>
</table>

robust ligature-induced model of murine periodontitis for the evaluation of oral neutrophils

The main advantages of studying the pathophysiology of periodontal disease utilizing murine models are the reduced cost of animals, array of genetically modified strains, the vast number of analyses that can be performed on harvested soft and hard tissues. However, many of these systems are subject to procedural criticisms. As an alternative, the ligature-induced model of periodontal disease, driven by the localized development and retention of a dysbiotic oral microbiome, can be employed, which is rapidly induced and relatively reliable. Unfortunately, the variants of ligature-induced murine periodontitis protocol are isolated to focal regions of the periodontium and subject to premature avulsion of the installed ligature. This minimizes the amount of tissue available for subsequent analyses and increases the number of animals required for study. This protocol describes the precise manipulations required to place extended molar ligatures with improved retention and usage of a novel rinse technique to recover oral neutrophils in mice with an alternative approach that mitigates the aforementioned technical challenges.

Representative flow cytometry data from oral rinse samples of a naive (Figure 3A) and inflamed (Figure 3B) murine oral cavity secondary to the ligature-induced periodontitis are provided. Recovery of PMNs from an installed ligature is also demonstrated (Figure 3C). Flow cytometer channel voltages were calibrated manually, and compensation was performed with single-stained compensati...

Watch this Scientific Journal Video about Robust Ligature-Induced Model of Murine Periodontitis for the Evaluation of Oral Neutrophils at JoVE.com

Robust Ligature-Induced Model of Murine Periodontitis for the Evaluation of Oral Neutrophils

This article presents a protocol for establishing a ligature-induced model of murine periodontitis involving multiple maxillary molars, resulting in larger areas of the involved gingival tissue and bone for subsequent analysis as well as reduced animal usage. A technique to assess oral neutrophils in a manner analogous to human subjects is also described.

The main advantages of studying the pathophysiology of periodontal disease utilizing murine models are the reduced cost of animals, array of genetically ...

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11.1K Views.  University Health Network. This article presents a protocol for establishing a ligature-induced model of murine periodontitis involving multiple maxillary molars, resulting in larger areas of the involved gingival tissue and bone for subsequent analysis as well as reduced animal usage. A technique to assess oral neutrophils in a manner analogous to human subjects is also described.

Video: Robust Ligature-Induced Model of Murine Periodontitis for the Evaluation of Oral Neutrophils

Murine Model of CD40-activation of B cells

Research on B cells has shown that CD40 activation improves their antigen presentation capacity. When stimulated with interleukin-4 and CD40 ligand (CD40L), human B cells can be expanded without difficulties from small amounts of peripheral blood within 14 days to very large amounts of highly-pure CD40-B cells (&gt;109 cells per patient) from healthy donors as well as cancer patients1-4. CD40-B cells express important lymph node homing molecules and can attract T cells in vitro5. Furthermore they efficiently take up, process and present antigens to T cells6,7. CD40-B cells were shown to not only prime na&iacute;ve, but also expand memory T cells8,9. Therefore CD40-activated B cells (CD40-B cells) have been studied as an alternative source of immuno-stimulatory antigen-presenting cells (APC) for cell-based immunotherapy1,5,10. In order to further study whether CD40-B cells induce effective T cell responses in vivo and to study the underlying mechanism we established a cell culture system for the generation of murine CD40-activated B cells. Using splenocytes or purified B cells from C57BL/6 mice for CD40-activation, optimal conditions were identified as follows: Starting from splenocytes of C57BL/6 mice (haplotype H-2b) lymphocytes are purified by density gradient centrifugation and co-cultured with HeLa cells expressing recombinant murine CD40 ligand (tmuCD40L HeLa)11. Cells are recultured every 3-4 days and key components such as CD40L, interleukin-4, -Mercaptoethanol and cyclosporin A are replenished. In this protocol we demonstrate how to obtain fully activated murine CD40-B cells (mCD40B) with similar APC-phenotype to human CD40-B cells (Fig 1a,b). CD40-stimulation leads to a rapid outgrowth and expansion of highly pure (&gt;90%) CD19+ B cells within 14 days of cell culture (Fig 1c,d). To avoid contamination with non-transfected cells, expression of the murine CD40 ligand on the transfectants has to be controlled regularly (Fig 2). Murine CD40-activated B cells can be used to study B-cell activation and differentiation as well as to investigate their potential to function as APC in vitro and in vivo. Moreover, they represent a promising tool for establishing therapeutic or preventive vaccination against tumors and will help to answer questions regarding safety and immunogenicity of this approach12.

In this video, we demonstrate the procedure of CD40-activation and expansion of murine B cells from splenocytes of C57BL/6 mice, which can be used as a model antigen-presenting cell (APC) to study induction of immunity.

Research on B cells has shown that CD40 activation improves their antigen presentation capacity. When stimulated with interleukin-4 and CD40 ligand ...

An Analytical Tool-box for Comprehensive Biochemical, Structural and Transcriptome Evaluation of Oral Biofilms Mediated by Mutans Streptococci

Biofilms are highly dynamic, organized and structured communities of microbial cells enmeshed in an extracellular matrix of variable density and composition 1, 2. In general, biofilms develop from initial microbial attachment on a surface followed by formation of cell clusters (or microcolonies) and further development and stabilization of the microcolonies, which occur in a complex extracellular matrix. The majority of biofilm matrices harbor exopolysaccharides (EPS), and dental biofilms are no exception; especially those associated with caries disease, which are mostly mediated by mutans streptococci 3. The EPS are synthesized by microorganisms (S. mutans, a key contributor) by means of extracellular enzymes, such as glucosyltransferases using sucrose primarily as substrate 3.
Studies of biofilms formed on tooth surfaces are particularly challenging owing to their constant exposure to environmental challenges associated with complex diet-host-microbial interactions occurring in the oral cavity. Better understanding of the dynamic changes of the structural organization and composition of the matrix, physiology and transcriptome/proteome profile of biofilm-cells in response to these complex interactions would further advance the current knowledge of how oral biofilms modulate pathogenicity. Therefore, we have developed an analytical tool-box to facilitate biofilm analysis at structural, biochemical and molecular levels by combining commonly available and novel techniques with custom-made software for data analysis. Standard analytical (colorimetric assays, RT-qPCR and microarrays) and novel fluorescence techniques (for simultaneous labeling of bacteria and EPS) were integrated with specific software for data analysis to address the complex nature of oral biofilm research.
The tool-box is comprised of 4 distinct but interconnected steps (Figure 1): 1) Bioassays, 2) Raw Data Input, 3) Data Processing, and 4) Data Analysis. We used our in vitro biofilm model and specific experimental conditions to demonstrate the usefulness and flexibility of the tool-box. The biofilm model is simple, reproducible and multiple replicates of a single experiment can be done simultaneously 4, 5. Moreover, it allows temporal evaluation, inclusion of various microbial species 5 and assessment of the effects of distinct experimental conditions (e.g. treatments 6; comparison of knockout mutants vs. parental strain 5; carbohydrates availability 7). Here, we describe two specific components of the tool-box, including (i) new software for microarray data mining/organization (MDV) and fluorescence imaging analysis (DUOSTAT), and (ii) in situ EPS-labeling. We also provide an experimental case showing how the tool-box can assist with biofilms analysis, data organization, integration and interpretation.

Biofilms formed on tooth surfaces are highly complex and exposed to constant innate and exogenous environmental challenges, which modulate their architecture, physiology and transcriptome. We developed a toolbox to examine the composition, structural organization and gene expression of oral biofilms, which can be adapted to other areas of biofilm research.

Biofilms are highly dynamic, organized and structured communities of microbial cells enmeshed in an extracellular matrix of variable density and ...

High-throughput Quantitative Real-time RT-PCR Assay for Determining Expression Profiles of Types I and III Interferon Subtypes

Described in this report is a qRT-PCR assay for the analysis of seventeen human IFN subtypes in a 384-well plate format that incorporates highly specific locked nucleic acid (LNA) and molecular beacon (MB) probes, transcript standards, automated multichannel pipetting, and plate drying. Determining expression among the type I interferons (IFN), especially the twelve IFN-&#945; subtypes, is limited by their shared sequence identity; likewise, the sequences of the type III IFN, especially IFN-&#955;2 and -&#955;3, are highly similar. This assay provides a reliable, reproducible, and relatively inexpensive means to analyze the expression of the seventeen interferon subtype transcripts.

This protocol describes a high-throughput qRT-PCR assay for the analysis of type I and III IFN expression signatures. The assay discriminates single base pair differences between the highly similar transcripts of these genes. Through batch assembly and robotic pipetting, the assays are consistent and reproducible.

Described in this report is a qRT-PCR assay for the analysis of seventeen human IFN subtypes in a 384-well plate format that incorporates highly specific ...

Oral Intubation of Adult Zebrafish: A Model for Evaluating Intestinal Uptake of Bioactive Compounds

Most pathogens invade organisms through their mucosa. This is particularly true in fish as they are continuously exposed to a microbial-rich water environment. Developing effective methods for oral delivery of immunostimulants or vaccines, which activate the immune system against infectious diseases, is highly desirable. In devising prophylactic tools, good experimental models are needed to test their performance. Here, we show a method for oral intubation of adult zebrafish and a set of procedures to dissect and prepare the intestine for cytometry, confocal microscopy and quantitative polymerase chain reaction (qPCR) analysis. With this protocol, we can precisely administer volumes up to 50 &#181;L to fish weighing approximately 1 g simply and quickly, without harming the animals. This method allows us to explore the direct in vivo uptake of fluorescently labelled compounds by the intestinal mucosa and the immunomodulatory capacity of such biologics at the local site after intubation. By combining downstream methods such as flow cytometry, histology, qPCR and confocal microscopy of the intestinal tissue, we can understand how immunostimulants or vaccines are able to cross the intestinal mucosal barriers, pass through the lamina propria, and reach the muscle, exerting an effect on the intestinal mucosal immune system. The model could be used to test candidate oral prophylactics and delivery systems or the local effect of any orally administered bioactive compound.

The protocol describes intubating adult zebrafish with a biologic; then dissecting and preparing the intestine for cytometry, confocal microscopy and qPCR. This method allows administration of bioactive compounds to monitor intestinal uptake and the local immune stimulus evoked. It&#160;is relevant for testing the intestinal dynamics of oral prophylactics.

Most pathogens invade organisms through their mucosa. This is particularly true in fish as they are continuously exposed to a microbial-rich water ...

Quantitative Polymerase Chain Reaction-based Analyses of Murine Intestinal Microbiota After Oral Antibiotic Treatment

The gut microbiota has a central influence on human health. Microbial dysbiosis is associated with many common immunopathologies such as inflammatory bowel disease, asthma and arthritis. Thus, understanding the mechanisms underlying microbiota-immune system crosstalk is of crucial importance. Antibiotic administration, while aiding pathogen clearance, also induces drastic changes in the size and composition of intestinal bacterial communities which can have an impact on human health. Antibiotic treatment in mice recapitulates the impact and long-term changes in human microbiota from antibiotic treated patients, and enables investigation of the mechanistic links between changes in microbial communities and immune cell function. While several methods for antibiotic treatment of mice have been described, some of them induce severe dehydration and weight-loss complicating the interpretation of the data. Here, we provide two protocols for oral antibiotic administration which can be used for long-term treatment of mice without inducing major weight-loss. These protocols make use of a combination of antibiotics that target both Gram-positive and Gram-negative bacteria and can be provided either ad libitum in the drinking water or by oral gavage. Moreover, we describe a method for the quantification of microbial density in fecal samples by qPCR which can be used to validate the efficacy of the antibiotic treatment. The combination of these approaches provides a reliable methodology for the manipulation of the intestinal microbiota and the study of the effects of antibiotic treatment in mice.

Here we provide detailed protocols for the oral administration of antibiotics to mice, collection of fecal samples, DNA extraction and quantification of fecal bacteria by qPCR.

The gut microbiota has a central influence on human health. Microbial dysbiosis is associated with many common immunopathologies such as inflammatory ...

A Galleria mellonella Oral Administration Model to Study Commensal-Induced Innate Immune Responses

The investigation of the immunogenic potential of commensal bacteria on the host immune system is one essential component when studying intestinal host-microbe interactions. It is well established that different commensals exhibit a different potential to stimulate the host intestinal immune system. Such investigations involve vertebrate animals, especially rodents. Since increasing ethical concerns are linked with experiments involving vertebrates, there is a high demand for invertebrate replacements models. 
Here, we provide a Galleria mellonella oral administration model using commensal non-pathogenic bacteria and the possible assessment of the immunogenic potential of commensals on the G. mellonella immune system. We demonstrate that G. mellonella is a useful alternative invertebrate replacement model that allows the analysis of commensals with different immunogenic potential such as Bacteroides vulgatus and Escherichia coli. Interestingly, the bacteria exhibited no killing effect on the larvae, which is similar to mammals. The immune responses of G. mellonella were comparable with vertebrate innate immune responses and involve recognition of the bacteria and production of antimicrobial molecules. We propose that G. mellonella was able to restore previous microbiota balance, which is well known from healthy mammalian individuals. Although providing comparable innate immune responses in both G. mellonella and vertebrates, G. mellonella does not harbor an adaptive immune system. Since the investigated components of the innate immune system are evolutionary conserved, the model allows a prescreening and first analysis of bacterial immunogenic properties.

A Galleria mellonella Oral Administration Model to Study Commensal-Induced Innate Immune Responses

Here, we provide a detailed protocol for an oral administration model using Galleria mellonella larvae and how to characterize induced innate immune responses. Using this protocol, researchers without practical experience will be able to use the G. mellonella force-feeding method.

The investigation of the immunogenic potential of commensal bacteria on the host immune system is one essential component when studying intestinal ...

A Contemporary Warming/Restraining Device for Efficient Tail Vein Injections in a Murine Fungal Sepsis Model

In rodent models, tail vein injections are important methods for intravenous administration of experimental agents. Tail vein injections typically involve warming of the animal to promote vasodilation, which aids in both the identification of the blood vessels and positioning of the needle into the vessel lumen while securely restraining the animal. Although tail vein injections are common procedures in many protocols and are not considered highly technical if performed correctly, accurate and consistent injections are crucial to obtain reproducible results and minimize variability. Conventional methods for inducing vasodilation prior to tail vein injections generally depend on the use of a heat source such as a heat lamp, electrical/rechargeable heat pads, or pre-heated water at 37 &#176;C. Despite being readily accessible in a standard laboratory setting, these tools evidently suffer from poor/limited thermo-regulatory capacity. Similarly, although various forms of restraining devices are commercially available, they must be used carefully to avoid trauma to the animals. These limitations of the current methods create unnecessary variables in experiments or result in varying outcomes between experiments and/or laboratories.
In this article, we demonstrate an improved protocol using an innovative device that combines an independent, thermally regulated, warming device with an adjustable restraining unit into one system for efficient streamlined tail vein injection. The example we use is an intravenous model of fungal bloodstream infection that results in sepsis. The warming apparatus consists of a heat-reflective acrylic box installed with an adjustable automatic thermostat to maintain the internal temperature at a pre-set threshold. Likewise, the width and height of the cone restraining apparatus can be adjusted to safely accommodate various rodent sizes. With the advanced and versatile features of the device, the technique shown here could become a useful tool across a range of research areas involving rodent models that employ tail vein injections.

Here, we present an effective and efficient method for rodent tail vein injections using a uniquely designed warming/restraining device. By streamlining the initiation of vasodilation and restraining processes, this protocol allows accurate and timely intravenous injections of large groups of animals with minimal distress.

In rodent models, tail vein injections are important methods for intravenous administration of experimental agents. Tail vein injections typically involve ...

Induction of Periodontitis via a Combination of Ligature and Lipopolysaccharide Injection in a Rat Model

Periodontitis (PD) is a highly prevalent, chronic immune-inflammatory disease of the periodontium, that results in a loss of gingival soft tissue, periodontal ligament, cementum, and alveolar bone. In this study, a simple method of PD induction in rats is described. We provide detailed instructions for placement of the ligature model around the first maxillary molars (M1) and a combination of injections of lipopolysaccharide (LPS), derived from Porphyromonas gingivalis at the mesio-palatal side of the M1. The induction of periodontitis was maintained for 14 days, promoting the accumulation of bacteria biofilm and inflammation. To validate the animal model, IL-1&#946;, a key inflammatory mediator, was determined by an immunoassay in the gingival crevicular fluid (GCF), and alveolar bone loss was calculated using cone beam computed tomography (CBCT). This technique was effective in promoting gingiva recession, alveolar bone loss, and an increase in IL-1&#946; levels in the GCF at the end of the experimental procedure after 14 days. This method was effective in inducing PD, thus being able to be used in studies on disease progression mechanisms and future possible treatments.

Induction of Periodontitis via a Combination of Ligature and Lipopolysaccharide Injection in a Rat Model

In this study, a rat model of induction of periodontitis is presented via a combination of retentive ligature and repetitive injections of lipopolysaccharide derived from Porphyromonas gingivalis, over 14 days around the first maxillary molars. The ligation and LPS injection techniques were effective in inducing peridontitis, resulting in alveolar bone loss and inflammation.

Periodontitis (PD) is a highly prevalent, chronic immune-inflammatory disease of the periodontium, that results in a loss of gingival soft tissue, ...

A Mouse Ear Model for Allergic Contact Dermatitis Evaluation

Skin is the human body&#39;s first line of defense and one of the most exposed organs to environmental chemicals. Allergic contact dermatitis (ACD) is a common skin disease that manifests as a local rash, redness, and skin lesions. The occurrence and development of ACD are influenced by both genetic and environmental factors. Although many scholars have constructed a series of models of ACD in recent years, the experimental protocols of these models are all different, which makes it difficult for readers to establish them well. Therefore, a stable and efficient animal model is of great significance to further study the pathogenesis of atopic dermatitis. In this study, we detail a modeling method using 1-fluoro-2,4-dinitrobenzene (DNFB) to induce ACD-like symptoms in the ears of mice and describe several methods for assessing the severity of dermatitis during modeling. This experimental protocol has been successfully applied in some experiments and has a certain promotional role in the field of ACD research.

Here, we describe the methods for inducing allergic contact dermatitis in mouse ears by 1-fluoro-2,4-dinitrobenzene (DNFB) and how to evaluate the severity of allergic contact dermatitis.

Skin is the human body&#39;s first line of defense and one of the most exposed organs to environmental chemicals. Allergic contact dermatitis (ACD) is a ...

Effective aPDT Using Curcuminoids for Oral Candidiasis in Mice

Curcuminoid-Mediated Antimicrobial Photodynamic Therapy on a Murine Model of Oral Candidiasis

Antimicrobial Photodynamic Therapy (aPDT) has been extensively investigated in vitro, and preclinical animal models of infections are suitable for evaluating alternative treatments prior to clinical trials. This study describes the efficacy of aPDT in a murine model of oral candidiasis. Forty mice were immunosuppressed with subcutaneous injections of prednisolone, and their tongues were inoculated using an oral swab previously soaked in a C. albicans cell suspension. Tetracycline was administered via drinking water during the course of the experiment. Five days after fungal inoculation, mice were randomly distributed into eight groups; a ninth group of untreated uninfected mice was included as a negative control (n = 5). Three concentrations (20 &#181;M, 40 &#181;M, and 80 &#181;M) of a mixture of curcuminoids were tested with a blue LED light (89.2 mW/cm2; ~455 nm) and without light (C+L+ and C+L- groups, respectively). Light alone (C-L+), no treatment (C-L-), and animals without infection were evaluated as controls. Data were analyzed using Welch&#39;s ANOVA and Games-Howell tests (&#945; = 0.05). Oral candidiasis was established in all infected animals and visualized macroscopically through the presence of characteristic white patches or pseudomembranes on the dorsum of the tongues. Histopathological sections confirmed a large presence of yeast and filaments limited to the keratinized layer of the epithelium in the C-L- group, and the presence of fungal cells was visually decreased in the images obtained from mice subjected to aPDT with either 40 &#181;M or 80 &#181;M curcuminoids. aPDT mediated by 80 &#181;M curcuminoids promoted a 2.47 log10 reduction in colony counts in comparison to those in the C-L- group (p = 0.008). All other groups showed no statistically significant reduction in the number of colonies, including photosensitizer (C+L-) or light alone (C-L+) groups. Curcuminoid-mediated aPDT reduced the fungal load from the tongues of mice.

Author Spotlight: Exploring Photodynamic Therapy with Curcumin in a Murine Model for Oral Candidiasis

This protocol describes the application of antimicrobial Photodynamic Therapy (aPDT) in a murine model of oral candidiasis. aPDT was performed using a water-soluble mixture of curcuminoids and blue LED light.