The study was supported by the Swedish Research Council, the Swedish Rheumatism Asociation, Karolinska Institute Foundations, Stockholm County Council, The Wallenberg Foundation, and the GV 80 Years' Foundation for research. The authors would also like to thank Hannah Aucott for proofreading the manuscript.

All animal experiments were performed according to the guidelines for the care and use of animals approved by the local Ethics Committee at Karolinska Institutet, Stockholm. The local Ethics Committee follows the European Union directives on animal care.
NOTE: The main changes from the original protocol are the recovery time after surgery (6 hr versus 1 hr) and the level of LPS injected (2 mg/kg versus 15 mg/kg). Otherwise, the different settings related to the surgery itself have not been changed.
1. Preparing Material for Stimulation
<ol>
	<li>Turn on the computer and the data acquisition system linked to the stimulating electrode (Figure 1A).</li>
	<li>Enter the Acknowledge program.</li>
	<li>Prepare a stock solution of LPS at a concentration of 5 mg/ml in 1x PBS, aliquot it, and store it at -20 &#176;C. On the day of the experiment, thaw an aliquot and prepare an adequate sample of LPS (0.5 mg/ml) in order to inject around 100 &#181;l into the animal, according to the weight.</li>
</ol>
2. Preparing the Animal for Anesthesia
<ol>
	<li>Use C57Bl/6 mice. Maintain them under climate-controlled conditions with a 12-hr light/dark cycle, feed them standard rodent chow, and give them water ad libitum.</li>
	<li>Perform surgery on mice that weigh around 25 g on the day of the experiment. 
	NOTE: When inflammatory reactions are induced, it is particularly important to perform regular checkups and observations of the clinical reactions in the animals. Premature euthanasia by CO2 inhalation is needed if the animal condition does not fulfill the ethical criteria.</li>
	<li>Set the anesthetic machine.
	<ol>
		<li>Make sure that the tubing is properly connected and is not damaged in any way. Make sure that the ventilated area is working properly. Connect the key filter to the isoflurane bottle and fill the vaporizer with a sufficient amount of isoflurane.</li>
		<li>Open the gas supply (air and oxygen) and make sure that the bottles contain enough gas for the experiment. A three-way connector is then able to send the isoflurane flow to the induction chamber or the mask.</li>
	</ol>
	</li>
	<li>Turn the three-way connector to the induction chamber. Pick one mouse from the home cage and insert the animal into the chamber. Adjust the flow regulator to 1.0 L/min oxygen and 1.0 L/min air. Adjust the isoflurane concentration to 4 - 5%.</li>
	<li>When the desired level of anesthesia is reached, When the desired level of anesthesia is reached, shave the surgical area and move the animal from the chamber to the mask.&#160;Turn the three-way connector to the mask flow. Adjust the flow regulator to 0.25 L/min oxygen and 0.25 L/min air.
	<ol>
		<li>Adjust the isoflurane concentration to 1.5 - 2.5%. Check the level of anesthesia by reflex control and respiratory rate before starting the surgical procedure.</li>
	</ol>
	</li>
	<li>Fix the legs of the mouse to the work bench using adhesive tape. Make sure that the nose of the animal is still carefully positioned in the mask.</li>
</ol>
3. Surgery and Stimulation of the Vagus Nerve
<ol>
	<li>Disinfect the surgical area with 70% ethanol.</li>
	<li>Using a scalpel, carefully incise the skin at the level of the neck (incision of around 1 to 1.5 cm). 
	Note: In the protocol, the surgery procedure ends here for SHAM-operated animals. Indeed, it has been shown that just touching the nerve with a metal tool already stimulates it to some extent. Therefore, to get a more accurate surgery control animal when using a small amount of LPS, stop the surgery at this step.</li>
	<li>With the help of a microscope (12.5X objective), isolate the left vagus nerve from the carotid artery using dissecting forceps. First locate the sternocleidomastoid muscle by removing skin and fat layers, and then retract it in order to put the forceps behind both the nerve and the artery. 
	Note: The following step is very tricky, as the nerve and artery are closely adhered to each other. Therefore, it is very easy to cut the vessel and kill the animal. However, by placing the forceps very carefully between the nerve and artery, they eventually separate, and it is possible to isolate the nerve.</li>
	<li>Place the electrode (Figure 1B) under the vagus nerve. The needle electrode is quite long, so even if the nerve moves slightly during the stimulation, it will always be in contact with the electrode.</li>
	<li>Perform an intraperitoneal (i.p.) injection of LPS (2 mg/kg) with the help of a syringe (for the read-out on cytokine levels; i.e., to measure the down-regulating effect).</li>
	<li>Wait 5 min before starting the stimulation.</li>
	<li>Stimulate the vagus nerve for 5 min at 5 V and 1 Hz by pushing the start button in the Acknowledge program.</li>
	<li>Remove the electrode and suture the wound of the animal with surgical suture thread.</li>
	<li>Spray a No Sting Barrier Film (NSBF) on the wound in order to improve healing and to protect from infections.</li>
</ol>
4. Recovery of the Animal
<ol>
	<li>After surgery, move the animal back to its home cage for awakening and recovery. Under infra-red light in order to maintain body temperature, make sure to monitor the animal until full consciousness has been regained.</li>
	<li>Let the animal recover in its cage for 6 hr before sacrifice for analysis. 
	Note: The effect of the vagus nerve stimulation is very fast and has also been shown to be long lasting (up to 48 hr), so the recovery time can be set by the experimenter according to the needs of the study.</li>
</ol>
5. Sacrifice for Further Analysis
<ol>
	<li>Place the animal in a cage linked to a CO2 administration device.</li>
	<li>Set the device on a 5-min cycle of CO2 inhalation.</li>
	<li>When the euthanasia is done, collect the organs of interest and directly freeze them on dry ice for further analysis (e.g., the measurement of cytokine levels in spleen extracts using a mouse TH1/TH2 9-Plex assay)3.</li>
</ol>

<ol>
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V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vagus+nerve+stimulation+attenuates+the+systemic+inflammatory+response+to+endotoxin.">Vagus nerve stimulation attenuates the systemic inflammatory response to endotoxin.</a> Nature. 405 (6785), 458-462 (2000).</li><li>Olofsson, P. S., Rosas-Ballina, M., Levine, Y. A., Tracey, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rethinking+inflammation:+neural+circuits+in+the+regulation+of+immunity.">Rethinking inflammation: neural circuits in the regulation of immunity.</a> Immunol. Rev. 248 (1), 188-204 (2012).</li><li>Pavlov, V. A., Tracey, K. 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The authors have nothing to disclose.

Since its discovery in the early 2000s, the mechanisms of the CAP have been thoroughly studied. We now have a good picture of the pathway, and in particular, the target organ, the spleen, where NE, memory T cells, Ach, and macrophages work as a very efficient team to down-regulate inflammatory mediators2. We have also recently published data on the importance of a functional prostaglandin system in mice, in particular, PGE2, which is obviously a mandatory component for ACh release in th...

Innate immunity provides an immediate first line of defense against infections and diseases in a wide range of organisms. It not only initiates the primary immune response to eliminate the threat, but it also plays a pivotal role in activating and educating the adaptive immunity that carries out secondary immune responses in a pathogen-specific manner. Inflammation is orchestrated by a plethora of cytokines and chemokines, which in turn have the ability to attract other immune cells to the site of infection and to induce the cardinal signs of inflammation, such as redness, swelling, pain, loss of function, and fever. The duration and intensity of inflammation depend on several factors, but resolving the inflammation and restoring homeostasis is a critical step to avoid the onset of chronic inflammatory diseases. Recent advances in the field of neuroscience and immunology have unraveled specific neural mechanisms with immense therapeutic potential to control inflammation both in the central nervous system and in the periphery. One of these mechanisms is the cholinergic anti-inflammatory pathway (CAP), also known as the inflammatory reflex, which is driven by the autonomic nervous system4,5.
It is currently thought that inflammatory mediators activate sensory nerves and send signals concerning the state of inflammation to the central nervous system. A reflex response is then activated through the efferent vagus nerve. An extensive study on the anatomical details of the CAP has revealed a parasympathetic-sympathetic model composed of two nerves, the vagus nerve and splenic nerve, respectively6. In the CAP, the activated cholinergic efferent vagus nerve ends in the celiac-mesenteric ganglion, resulting in the activation of the adrenergic splenic nerve by a mechanism yet to be explored. The splenic nerve, thus activated, is known to innervate in close proximity to immune cells in the white pulp, marginal zone, and red pulp of the spleen, the principal and mandatory organ of the CAP7,8. Norepinephrine (NE) from the splenic nerve endings binds to the corresponding &#946;2 adrenergic receptors expressed on splenic T lymphocytes. This induces choline acetyl transferase (ChAT)-mediated acetylcholine (ACh) release, which in turn activates &#945;7 nicotinic acetylcholine receptors (&#945;7nACh) on macrophages, thereby limiting cytokine production and inflammation2. Consequently, it is now clear that the nervous system is able to regulate inflammation in peripheral tissues and to restore local immune homeostasis.
As the name of the pathway suggests, the ACh system is of central importance to the functioning of this neuro-immune regulating pathway. Interestingly, the mechanisms involved in the activation of the CAP seem to be different in the periphery and in the central nervous system. While the importance of nicotinic receptors (&#945;7nAChR) in the spleen has been demonstrated earlier9, muscarinic receptors (mAChR) are mandatory for the central activation of the pathway10,11. More recently, peripheral administration of a centrally-acting M1 muscarinic agonist significantly suppressed serum and spleen tumor necrosis factor &#945; (TNF&#945;) during lethal murine endotoxemia, an action that required intact vagus nerve and splenic nerve signaling12. We have also shown recently that mice lacking prostaglandin E2 (PGE2) were not able to respond to vagus nerve stimulation and did not down-regulate the LPS-induced release of cytokines in the serum and spleen3. Therefore, the CAP might also be regulated by systems other than the main ACh pathway.
The vagus nerve has been named as such because of its wandering course in the body, innervating principal organs including the liver, lung, spleen, kidneys, and gut13. Considering this large innervation and the very potent immunosuppressive effect of the vagus nerve, the therapeutic potential of the CAP could cover a wide range of inflammatory conditions. The vagus nerve can be electrically (or mechanically) activated, with control over the voltage and frequency, and contrary to conventional treatment, with no drugs added to the body. Trials are currently underway in rheumatic patients, for instance, to test the clinical significance of VNS in treating chronic inflammation14. Altogether, the neuro-immune communication and regulation of inflammation are currently under investigation, which will provide a possible alternative treatment to conventional therapy. Therefore, analysis of the vagus nerve stimulation effect in the different innervated organs, but also characterization of the potential therapeutic action in animal models of chronic inflammation, would definitely give insights and hope for new potential therapeutic targets.
The original methodology developed by Tracey and colleagues4 could not be transposed to our field of research due to overstimulation of the inflammatory response (by a lethal dose of LPS) and a too-short time range between CAP activation and the read-out. In the present paper, we will present the changes made to the original protocol, compare the two different methodologies on cytokine levels, and highlight a new and opposite observation on the target organ (the spleen).

<table border="0" cellpadding="0" cellspacing="0" width="665">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">Computer</td>
			<td style="width:91px;">Toshiba</td>
			<td style="width:136px;">-</td>
			<td style="width:191px;">Any computer is actually compatible</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">MP-150 data acquisition system</td>
			<td style="width:91px;">Biopac Systems</td>
			<td rowspan="2" style="width:136px;">MP150WSW</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Acknowledge software</td>
			<td style="width:91px;">Biopac Systems</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Mice C57Bl/6</td>
			<td style="width:91px;">Charles River</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Anesthetic machine</td>
			<td style="width:91px;">Simtec Engineering</td>
			<td style="width:136px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">Medical oxygen bottle</td>
			<td style="width:91px;">AGA</td>
			<td style="width:136px;">107563</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">Medical air bottle&#160;</td>
			<td style="width:91px;">AGA</td>
			<td style="width:136px;">108639</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">Vetflurane (1000mg/g)</td>
			<td style="width:91px;">Virbac</td>
			<td style="width:136px;">137317</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">LPS</td>
			<td style="width:91px;">Sigma-Aldrich</td>
			<td style="width:136px;">L2630</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Saline</td>
			<td style="width:91px;">Merck Millipore</td>
			<td style="width:136px;">1024060080</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">PBS 10X</td>
			<td style="width:91px;">Sigma-Aldrich</td>
			<td style="width:136px;">P5493</td>
			<td>Diluted 10 times for used concentration</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">Syringe (1 ml)</td>
			<td style="width:91px;">BD Plastipak</td>
			<td style="width:136px;">303172</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">Needles 23G</td>
			<td style="width:91px;">KD-FINE</td>
			<td style="width:136px;">900284</td>
			<td>0.6 x 30 mm (blue)</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Microdissecting forceps (curved)</td>
			<td style="width:91px;">Sigma-Aldrich</td>
			<td style="width:136px;">F4142</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Dissecting scissors</td>
			<td style="width:91px;">Sigma-Aldrich</td>
			<td style="width:136px;">Z265969</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:247px;">Surgical suture 4-0</td>
			<td style="width:91px;">Ethicon</td>
			<td style="width:136px;">G667G</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Euthanasia unit</td>
			<td style="width:91px;">Euthanex Smartbox</td>
			<td style="width:136px;">EA-32000</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">Cavilon No Sting Barrier Film</td>
			<td style="width:91px;">3M Health Care</td>
			<td style="width:136px;">3346N</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:247px;">TH1/TH2 9-Plex assay, ultrasensitive kit</td>
			<td style="width:91px;">MesoScale Discovery</td>
			<td style="width:136px;">K15013C-1</td>
			<td></td>
		</tr>
	</tbody>
</table>

increased recovery time and decreased lps administration to study the vagus nerve stimulation mechanisms in limited inflammatory responses

Inflammation is a local response to infection and tissue damage mediated by activated macrophages, monocytes, and other immune cells that release cytokines and other mediators of inflammation. For a long time, humoral and cellular mechanisms have been studied for their role in regulating the immune response, but recent advances in the field of immunology and neuroscience have also unraveled specific neural mechanisms with interesting therapeutic potential. The so-called cholinergic anti-inflammatory pathway (CAP) has been described to control innate immune responses and inflammation in a very potent manner. In the early 2000s, Tracey and collaborators developed a technique that stimulates the vagus nerve and mimics the effect of the pathway. The methodology is based on the electrical stimulation of the vagus nerve at low voltage and frequency, in order to avoid any side effects of overstimulation, such as deregulation of heart rate variability. Electrical devices for stimulation are now available, making it easy to set up the methodology in the laboratory. The goal of this research was to investigate the potential involvement of prostaglandins in the CAP. Unfortunately, based on earlier attempts, we failed to use the original protocol, as the induced inflammatory response either was too high or was not suitable for enzymatic metabolism properties. The different settings of the original surgery protocol remained mostly unchanged, but the conditions regarding inflammatory induction and the time point before sacrifice were improved to fit our purposes (i.e., to investigate the involvement of the CAP in more limited inflammatory responses). 
The modified version of the original protocol, presented here, includes a longer time range between vagus nerve stimulation and analysis, which is associated with a lower induction of inflammatory responses. Additionally, while decreasing the level of lipopolysaccharides (LPS) to inject, we also came across new observations regarding mechanistic properties in the spleen.

Level of TNF&#945; and Interleukin-1&#946; (IL-1&#946;) after Increasing the Time Lapse after Surgery and Decreasing the Dose of LPS
As shown previously, using the original protocol, VNS decreased the levels of TNF&#945; (169.3 &#177; 24.9 pg/mg in SHAM versus 39.7 &#177; 10.8 pg/mg in VNS, p &#60; 0.001) and IL-1&#946; (360.0 &#177; 40.21 pg/mg in SHAM versus 191.7 &#177; 27.2 pg/mg in VNS, p &#60; 0.01) in the spleen after intrap...

Watch this Scientific Journal Video about Increased Recovery Time and Decreased LPS Administration to Study the Vagus Nerve Stimulation Mechanisms in Limited Inflammatory Responses at JoVE.com

Increased Recovery Time and Decreased LPS Administration to Study the Vagus Nerve Stimulation Mechanisms in Limited Inflammatory Responses

Vagus nerve stimulation has proven to have a strong efficacy for decreasing peripheral inflammation. Here, we present a modified vagus nerve stimulation protocol that allows for further examinations of the cholinergic anti-inflammatory mechanisms in limited inflammatory responses.

Inflammation is a local response to infection and tissue damage mediated by activated macrophages, monocytes, and other immune cells that release ...

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Research

JoVE Journal

Immunology and Infection

9.8K Views.  Karolinska University Hospital. Vagus nerve stimulation has proven to have a strong efficacy for decreasing peripheral inflammation. Here, we present a modified vagus nerve stimulation protocol that allows for further examinations of the cholinergic anti-inflammatory mechanisms in limited inflammatory responses.

Video: Increased Recovery Time and Decreased LPS Administration to Study the Vagus Nerve Stimulation Mechanisms in Limited Inflammatory Responses

Differentiating Functional Roles of Gene Expression from Immune and Non-immune Cells in Mouse Colitis by Bone Marrow Transplantation

To understand the role of a gene in the development of colitis, we compared the responses of wild-type mice and gene-of-interest deficient knockout mice to colitis. If the gene-of-interest is expressed in both bone marrow derived cells and non-bone marrow derived cells of the host; however, it is possible to differentiate the role of a gene of interest in bone marrow derived cells and non- bone marrow derived cells by bone marrow transplantation technique. To change the bone marrow derived cell genotype of mice, the original bone marrow of recipient mice were destroyed by irradiation and then replaced by new donor bone marrow of different genotype. When wild-type mice donor bone marrow was transplanted to knockout mice, we could generate knockout mice with wild-type gene expression in bone marrow derived cells. Alternatively, when knockout mice donor bone marrow was transplanted to wild-type recipient mice, wild-type mice without gene-of-interest expressing from bone marrow derived cells were produced. However, bone marrow transplantation may not be 100% complete. Therefore, we utilized cluster of differentiation (CD) molecules (CD45.1 and CD45.2) as markers of donor and recipient cells to track the proportion of donor bone marrow derived cells in recipient mice and success of bone marrow transplantation. Wild-type mice with CD45.1 genotype and knockout mice with CD45.2 genotype were used. After irradiation of recipient mice, the donor bone marrow cells of different genotypes were infused into the recipient mice. When the new bone marrow regenerated to take over its immunity, the mice were challenged by chemical agent (dextran sodium sulfate, DSS 5%) to induce colitis. Here we also showed the method to induce colitis in mice and evaluate the role of the gene of interest expressed from bone-marrow derived cells. If the gene-of-interest from the bone derived cells plays an important role in the development of the disease (such as colitis), the phenotype of the recipient mice with bone marrow transplantation can be significantly altered. At the end of colitis experiments, the bone marrow derived cells in blood and bone marrow were labeled with antibodies against CD45.1 and CD45.2 and their quantitative ratio of existence could be used to evaluate the success of bone marrow transplantation by flow cytometry. Successful bone marrow transplantation should show a vast majority of donor genotype (in term of CD molecule marker) over recipient genotype in both the bone marrow and blood of recipient mice.

Bone marrow transplantation provides a way to change the genotype of the bone marrow derived cells. If the gene of interest is expressed in both bone marrow derived cells and non-bone marrow derived cells, bone marrow transplantation can change the bone marrow derived cells to a different genotype without changing the non-bone marrow derived cell genotype.

To understand the role of a gene in the development of colitis, we compared the responses of wild-type mice and gene-of-interest deficient knockout mice ...

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 ...

Transplantation of Tail Skin to Study Allogeneic CD4 T Cell Responses in Mice

The study of T cell responses and their consequences during allo-antigen recognition requires a model that enables one to distinguish between donor and host T cells, to easily monitor the graft, and to adapt the system in order to answer different immunological questions. Medawar and colleagues established allogeneic tail-skin transplantation in mice in 1955. Since then, the skin transplantation model has been continuously modified and adapted to answer specific questions. The use of tail-skin renders this model easy to score for graft rejection, requires neither extensive preparation nor deep anesthesia, is applicable to animals of all genetic background, discourages ischemic necrosis, and permits chemical and biological intervention. 
In general, both CD4+ and CD8+ allogeneic T cells are responsible for the rejection of allografts since they recognize mismatched major histocompatibility antigens from different mouse strains. Several models have been described for activating allogeneic T cells in skin-transplanted mice. The identification of major histocompatibility complex (MHC) class I and II molecules in different mouse strains including C57BL/6 mice was an important step toward understanding and studying T cell-mediated alloresponses. In the tail-skin transplantation model described here, a three-point mutation (I-Abm12) in the antigen-presenting groove of the MHC-class II (I-Ab) molecule is sufficient to induce strong allogeneic CD4+ T cell activation in C57BL/6 mice. Skin grafts from I-Abm12 mice on C57BL/6 mice are rejected within 12-15 days, while syngeneic grafts are accepted for up to 100 days. The absence of T cells (CD3-/- and Rag2-/- mice) allows skin graft acceptance up to 100 days, which can be overcome by transferring 2 x 104 wild type or transgenic T cells. Adoptively transferred T cells proliferate and produce IFN-&#947; in I-Abm12-transplanted Rag2-/- mice.

Tail-skin transplantation is a powerful model for studying T cell-dependent rejection and tolerance induction during allogeneic immune responses in mice. The advantages of this protocol are minor invasive surgery, and ease of monitoring with no need to sacrifice the recipient mouse.

The study of T cell responses and their consequences during allo-antigen recognition requires a model that enables one to distinguish between donor 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 ...

Intranasal Administration of Recombinant Influenza Vaccines in Chimeric Mouse Models to Study Mucosal Immunity

Vaccines are one of the greatest achievements of mankind, and have saved millions of lives over the last century. Paradoxically, little is known about the physiological mechanisms that mediate immune responses to vaccines perhaps due to the overall success of vaccination, which has reduced interest into the molecular and physiological mechanisms of vaccine immunity. However, several important human pathogens including influenza virus still pose a challenge for vaccination, and may benefit from immune-based strategies. 
Although influenza reverse genetics has been successfully applied to the generation of live-attenuated influenza vaccines (LAIVs), the addition of molecular tools in vaccine preparations such as tracer components to follow up the kinetics of vaccination in vivo, has not been addressed. In addition, the recent generation of mouse models that allow specific depletion of leukocytes during kinetic studies has opened a window of opportunity to understand the basic immune mechanisms underlying vaccine-elicited protection. Here, we describe how the combination of reverse genetics and chimeric mouse models may help to provide new insights into how vaccines work at physiological and molecular levels, using as example a recombinant, cold-adapted, live-attenuated influenza vaccine (LAIV). We utilized laboratory-generated LAIVs harboring cell tracers as well as competitive bone marrow chimeras (BMCs) to determine the early kinetics of vaccine immunity and the main physiological mechanisms responsible for the initiation of vaccine-specific adaptive immunity. In addition, we show how this technique may facilitate gene function studies in single animals during immune responses to vaccines. We propose that this technique can be applied to improve current prophylactic strategies against pathogens for which urgent medical countermeasures are needed, for example influenza, HIV, Plasmodium, and hemorrhagic fever viruses such as Ebola virus.

There is an overall lack of knowledge about how vaccines work. Here we propose the combined use of reverse genetics and bone marrow chimeric mice to gain insight into the early host immune responses to vaccines with a special focus on dendritic cells and T cell immunity.

Vaccines are one of the greatest achievements of mankind, and have saved millions of lives over the last century. Paradoxically, little is known about the ...

Intra-tracheal Administration of Haemophilus influenzae in Mouse Models to Study Airway Inflammation

Here, we describe a detailed procedure to efficiently and directly deliver Haemophilus influenzae into the lower respiratory tracts of mice. We demonstrate the procedure for preparing H. influenzae inoculum, intra-tracheal instillation of H. influenzae into the lung, collection of broncho-alveolar lavage fluid (BALF), analysis of immune cells in the BALF, and RNA isolation for differential gene expression analysis. This procedure can be used to study the lung inflammatory response to any bacteria, virus or fungi. Direct tracheal instillation is mostly preferred over intranasal or aerosol inhalation procedures because it more efficiently delivers the bacterial inoculum into the lower respiratory tract with less ambiguity.

Intra-tracheal Administration of Haemophilus influenzae in Mouse Models to Study Airway Inflammation

We demonstrate the procedure for intra-tracheal inoculation of Haemophilus influenzae into the lower respiratory tracts of mice. This is a very useful tool to study signaling pathways that regulate airway inflammation in mouse models.

Here, we describe a detailed procedure to efficiently and directly deliver Haemophilus influenzae into the lower respiratory tracts of mice. We ...

Retroviral Transduction of Helper T Cells as a Genetic Approach to Study Mechanisms Controlling their Differentiation and Function

Helper T cell development and function must be tightly regulated to induce an appropriate immune response that eliminates specific pathogens yet prevents autoimmunity. Many approaches involving different model organisms have been utilized to understand the mechanisms controlling helper T cell development and function. However, studies using mouse models have proven to be highly informative due to the availability of genetic, cellular, and biochemical systems. One genetic approach in mice used by many labs involves retroviral transduction of primary helper T cells. This is a powerful approach due to its relative ease, making it accessible to almost any laboratory with basic skills in molecular biology and immunology. Therefore, multiple genes in wild type or mutant forms can readily be tested for function in helper T cells to understand their importance and mechanisms of action. We have optimized this approach and describe here the protocols for production of high titer retroviruses, isolation of primary murine helper T cells, and their transduction by retroviruses and differentiation toward the different helper subsets. Finally, the use of this approach is described in uncovering mechanisms utilized by microRNAs (miRNAs) to regulate pathways controlling helper T cell development and function.

Many experimental systems have been utilized to understand the mechanisms regulating T cell development and function in an immune response. Here a genetic approach using retroviral transduction is described, which is economic, time efficient, and most importantly, highly informative in identifying regulatory pathways.

Helper T cell development and function must be tightly regulated to induce an appropriate immune response that eliminates specific pathogens yet prevents ...

An IL-8 Transiently Transgenized Mouse Model for the In Vivo Long-term Monitoring of Inflammatory Responses

Airway inflammation is often associated with bacterial infections and represents a major determinant of lung disease. The in vivo determination of the pro-inflammatory capabilities of various factors is challenging and requires terminal procedures, such as bronchoalveolar lavage and the removal of lungs for in situ analysis, precluding longitudinal visualization in the same mouse. Here, lung inflammation is induced through the intratracheal instillation of Pseudomonas aeruginosa culture supernatant (SN) in transiently transgenized mice expressing the luciferase reporter gene under the control of a heterologous IL-8 bovine promoter. Luciferase expression in the lung is monitored by in vivo bioluminescent image (BLI) analysis over a 2.5- to 48-h timeframe following the instillation. The procedure can be repeated multiple times within 2 - 3 months, thus permitting the evaluation of the inflammatory response in the same mice without the need to terminate the animals. This approach permits the monitoring of pro- and anti-inflammatory factors acting in the lung in real time and appears suitable for functional and pharmacological studies.

An IL-8 Transiently Transgenized Mouse Model for the In Vivo Long-term Monitoring of Inflammatory Responses

The method described here allows for the visualization of IL-8 promoter-dependent inflammation activation in the lungs of mice through non-invasive bioluminescence imaging (BLI). The same animal can be subjected to BLI multiple times for up to two months from the time of delivery of the luciferase reporter construct.

Airway inflammation is often associated with bacterial infections and represents a major determinant of lung disease. The in vivo determination of the ...

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 ...

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

Salmonella typhimurium is a facultative intracellular bacterium that causes gastroenteritis in humans. After invasion of the lamina propria, S. typhimurium bacteria are quickly detected and phagocytized by macrophages, and contained in vesicles known as phagosomes in order to be degraded. Isolation of S. typhimurium-containing phagosomes have been widely used to study how S. typhimurium infection alters the process of phagosome maturation to prevent bacterial degradation. Classically, the isolation of bacteria-containing phagosomes has been performed by sucrose gradient centrifugation. However, this process is time-consuming, and requires specialized equipment and a certain degree of dexterity. Described here is a simple and quick method for the isolation of S. typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin-streptavidin-conjugated magnetic beads. Phagosomes obtained by this method can be suspended in any buffer of choice, allowing the utilization of isolated phagosomes for a broad range of assays, such as protein, metabolite, and lipid analysis. In summary, this method for the isolation of S. typhimurium-containing phagosomes is specific, efficient, rapid, requires minimum equipment, and is more versatile than the classical method of isolation by sucrose gradient-ultracentrifugation.

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

We describe here a simple and quick method for the isolation of Salmonella typhimurium-containing phagosomes from macrophages by coating the bacteria with biotin and streptavidin.