This work is supported by grants from the National Natural Sciences Foundation of China (81671016, 31471008, and 31661143030) and National Institutes of Health (DC010012, DC015819) and by the Siyuan Foundation.

All experiments involving mice were reviewed and approved by the Institutional Animal Care and Use Committees of Zhejiang University. It is advised to wear appropriate personal protective equipment before performing this protocol.
1. Preparation of Mice and DSS
<ol>
	<li>Keep the knockout (&#945;-gustducin-/-) mice and age-, gender-, and body weight-matched wild-type control (&#945;-gustducin+/+) C57BL/6 mice individually in clean cages. 
	NOTE: The knockout mice h...

<ol>
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A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+transient+receptor+potential+channel+expressed+in+taste+receptor+cells.">A transient receptor potential channel expressed in taste receptor cells.</a> Nature Neuroscience. 5 (11), 1169-1176 (2002).</li><li>Shigemura, N., Ninomiya, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+Advances+in+Molecular+Mechanisms+of+Taste+Signaling+and+Modifying.">Recent Advances in Molecular Mechanisms of Taste Signaling and Modifying.</a> International Review of Cell and Molecular Biology. 323, 71-106 (2016).</li><li>Bezen&#231;on, C., 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=Murine+intestinal+cells+expressing+Trpm5+are+mostly+brush+cells+and+express+markers+of+neuronal+and+inflammatory+cells.">Murine intestinal cells expressing Trpm5 are mostly brush cells and express markers of neuronal and inflammatory cells.</a> Journal of Comparative Neurology. 509 (5), 514-525 (2008).</li><li>Lu, P., Zhang, C. -. 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D., Malleshappa, M., Vijay-Kumar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dextran+sulfate+sodium+(DSS)-induced+colitis+in+mice.">Dextran sulfate sodium (DSS)-induced colitis in mice.</a> Current Protocols in Immunology. 104 (25), (2014).</li><li>Feng, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aggravated+gut+inflammation+in+mice+lacking+the+taste+signaling+protein+&#945;-gustducin.">Aggravated gut inflammation in mice lacking the taste signaling protein &#945;-gustducin.</a> Brain, Behavior, and Immunity. 71, 23-27 (2018).</li><li>Feng, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immune+cells+of+the+human+peripheral+taste+system:+Dominant+dendritic+cells+and+CD4+T+cells.">Immune cells of the human peripheral taste system: Dominant dendritic cells and CD4 T cells.</a> Brain, Behavior, and Immunity. 23 (6), 760-766 (2009).</li><li>Livak, K. 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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+Colitis+Modeling+using+Dextran+Sulfate+Sodium+(DSS).">Murine Colitis Modeling using Dextran Sulfate Sodium (DSS).</a> Journal of Visualized Experiments. (35), 1652 (2010).</li><li>Howitt, M. R., 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=Tuft+cells,+taste-chemosensory+cells,+orchestrate+parasite+type+2+immunity+in+the+gut.">Tuft cells, taste-chemosensory cells, orchestrate parasite type 2 immunity in the gut.</a> Science. 351 (6279), 1329-1333 (2016).</li></ol>

The authors declare that they have no competing financial interests.

This method can be employed to quantitively determine the effect of mutations of specific gustatory genes on inflammation in a DSS-induced IBD mouse model. To take full advantage, optimal induction of IBD is a key step. The development of colitis is affected by several factors, including mouse strain, housing environment, intestinal microflora, as well as the genes of interest. It is recommended to perform a pilot experiment with a small number of mice to test different dosages and durations of DSS administration. During...

The two major forms of inflammatory bowel disease (IBD), Crohn&#39;s disease (CD), and ulcerative colitis (UC) are characterized by chronic remittent or progressive inflammatory conditions of the intestine with multifactorial etiology1,2. The development of IBD depends on genetic as well as certain environmental factors such as diet, antibiotic use, and importantly, pathogenic infections. However, the etiology and regulatory molecular mechanisms underlying IBD are still unclear. Hence, numerous chemically induced IBD animal models have been constructed and applied to delineate the pathogenesis and regulatory mechanisms and evaluate the effectiveness of human therapeutics3.
Taste receptors are G protein-coupled receptors (GPCRs) and are classified as two major types: type I (T1Rs), and type II (T2Rs) that detect sweet, umami, and bitter compounds. Taste signaling cascades are initiated by tastant binding to T1Rs or T2Rs, activating the heterotrimeric G proteins consisting of &#945;-gustducin and a G&#946;&#947; dimer and leading to release of the G&#946;&#947; subunits. The G&#946;&#947; moiety in turn stimulates the downstream effector enzyme phospholipase C-&#946;2 (PLC-&#946;2). Activated PLC-&#946;2 then hydrolyzes phosphatidylinositol-4,5-bisphosphate into two intracellular secondary messengers [inositol-1,4,5-trisphosphate (IP3) and diacylglycerol], and IP3 binds to and open its channel-receptor IP3R3, releasing calcium ions from the endoplasmic reticulum. This eventually leads to the opening of transient receptor potential ion channel Trpm5 and release of the neurotransmitter ATP onto the gustatory nerves4,5,6,7. Yet, the signaling pathways of salty and sour tastes are different and independent from sweet, umami, and bitter tastes8. In addition, the components of taste GPCRs and downstream proteins exist in various extra-oral tissues. Recent studies indicated that &#945;-gustducin, the principal component of taste signaling, is found to be expressed in the intestinal mucosa. Further studies are needed to understand the functions of these taste signaling components in extra-oral tissues9,10.
The method described here is used to characterize functions of the gustatory signaling proteins expressed in extra-oral tissues. We combine a transgenic mouse line developed for delineating signaling cascades in taste buds with the chemically induced colitis model. Largely due to its procedural simplicity and pathological similarities to human ulcerative colitis, the dextran sulfate sodium (DSS)-induced IBD model has been most widely used among the various chemically induced colitis models11. In this study, we used &#945;-gustducin-deficient mice as a representative mouse line to reveal novel functions of &#945;-gustducin in gut mucosal immunity and inflammation by 1) analyzing morphological changes in the tissue and 2) assaying differences in the expression of cytokines related to inflammation in the colon. This method can be used to quantitatively and qualitatively determine the contributions of gustatory signaling proteins (and other proteins expressed in the gut) to tissue damage and intestinal inflammation, when genetically modified mouse lines for the genes of interest are available. Advantages of this method are enabling users to obtain integrated data resulting from actions of both the chemical DSS and deficiency of the gene of interest. This method can be further improved to increase its sensitivity and reveal subtle intestinal changes at the cellular and molecular levels.

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	<tbody>
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			<td height="20" style="height:20px;width:269px;">Antibody</td>
			<td style="width:139px;"></td>
			<td style="width:87px;"></td>
			<td style="width:64px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD45</td>
			<td>BD Biosciences</td>
			<td>550539</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD3</td>
			<td>BD Biosciences</td>
			<td>555273</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">B220</td>
			<td>BD Biosciences</td>
			<td>550286</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD11b</td>
			<td>BD Biosciences</td>
			<td>550282</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ly6G</td>
			<td>BD Biosciences</td>
			<td>551459</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Reagent</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dextran Sulfate Sodium Salt (DSS)</td>
			<td>MP Biomedicals</td>
			<td>2160110</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Streptavidin-HRP complex</td>
			<td>BD Pharmingen</td>
			<td>551011</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">H&#38;E Staining Kit</td>
			<td>BBI Life Sciences</td>
			<td>E607318</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate Buffered Saline (PBS)</td>
			<td>Sangon Biotech</td>
			<td>B548117</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FastStart Universal SYBR Green Master(ROX)</td>
			<td>Roche</td>
			<td>4913850001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MMLV Reverse Transcriptase, GPR</td>
			<td>Clontech,TaKaRa</td>
			<td>639574</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TaKaRa MiniBEST Universal RNA Extraction Kit&#160;</td>
			<td>TaKaRa</td>
			<td>9767</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD 10 ml Syringe</td>
			<td>BD Biosciences</td>
			<td>309604</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Instruments and equipment</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">balance</td>
			<td></td>
			<td></td>
			<td></td>
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		<tr height="20">
			<td height="20" style="height:20px;">scissors&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">forceps</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">centrifuge</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">qPCR machine</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">staining jars</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Software</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Imag-Pro Plus&#160;</td>
			<td colspan="2">Media Cybernetics, Inc.&#160;</td>
			<td></td>
		</tr>
	</tbody>
</table>

effects of taste signaling protein abolishment on gut inflammation in an inflammatory bowel disease mouse model

Inflammatory bowel disease (IBD) is one of the immune-related gastrointestinal disorders, including ulcerative colitis and Crohn's disease, that affects the life quality of millions of people worldwide. IBD symptoms include abdominal pain, diarrhea, and rectal bleeding, which may result from the interactions among gut microbiota, food components, intestinal epithelial cells, and immune cells. It is of particular importance to assess how each key gene expressed in intestinal epithelial and immune cells affects inflammation in the colon. G protein-coupled taste receptors, including G protein subunit &#945;-gustducin and other signaling proteins, have been found in the intestines. Here, we use &#945;-gustducin as a representative and describe a dextran sulfate sodium (DSS)-induced IBD model to evaluate the effect of gustatory gene mutations on gut mucosal immunity and inflammation. This method combines gene knockout technology with the chemically induced IBD model, and thus can be applied to assess the outcome of gustatory gene nullification as well as other genes that may exuberate or dampen the DSS-induced immune response in the colon. Mutant mice are administered with DSS for a certain period during which their body weight, stool, and rectal bleeding are monitored and recorded. At different timepoints during administration, some mice are euthanized, then the sizes and weights of their spleens and colons are measured and gut tissues are collected and processed for histological and gene expression analyses. The data show that the &#945;-gustducin knockout results in excessive weight loss, diarrhea, intestinal bleeding, tissue damage, and inflammation vs. wild-type mice. Since the severity of induced inflammation is affected by mouse strains, housing environment, and diet, optimization of DSS concentration and administration duration in a pilot experiment is particularly important. By adjusting these factors, this method can be applied to assess both anti- and pro-inflammatory effects.

A DSS-induced IBD procedure was established by administrating 3% DSS in drinking water to &#945;-gustducin-knockout (KO) and wild-type (WT) mice. Compared to WT mice, the knockout mice exhibited more severe colitis with excessive weight loss, diarrhea, and intestinal bleeding (Figure 1). After a 7 day DSS administration, the differences in tissue integrity were analyzed using H&#38;E staining as the histological method, and more aggravated tissue damage was f...

Watch this Scientific Journal Video about Effects of Taste Signaling Protein Abolishment on Gut Inflammation in an Inflammatory Bowel Disease Mouse Model at JoVE.com

Effects of Taste Signaling Protein Abolishment on Gut Inflammation in an Inflammatory Bowel Disease Mouse Model

Here we present a protocol to investigate the effect of the nullification of gustation-related genes on immune responses in a dextran sulfate sodium (DSS)-induced inflammatory bowel disease (IBD) mouse model.

Inflammatory bowel disease (IBD) is one of the immune-related gastrointestinal disorders, including ulcerative colitis and Crohn's disease, that affects ...

This method can help answer key questions in the inflammatory biodisease field about ulcerative colitis and Crohn's disease. The main advantage of this technique is that it can be used to evaluate first anti and proinfammatory effects of signaling proteins. The implication of this technique extends the survey of gas in new advances and inflammation.Though this method can provide insights into genetic effect on gut inflammation. It can also be applied to other factors such as diets and microbiome. Generally, individuals new to this semester will struggle because processing disease scar tissue is tricky.Visual demonstration of this method is critical as dissection and the tissue preparation steps are difficult to learn because mystalia and the cell tissue structures may be altered. To induce dextran sulfate sodium, or DDS colitis, replace the regular drinking water with 3%DSS solution, add libidium for seven days. Measuring each mouses'body weight, DSS solution consumption, and stool production daily.At the end of the seven day treatment, place the mouse in the supine position and use small scissors to make a three centimeter long midline incision in the abdomen. Harvest the spleen and measure its size. Then use forceps to lift the colon to allow it to be separated from the surrounding mesentery.And extract the whole colon until the cecum and rectum are visible. Transect the tissue at the colonosecal margin. And deep within the pelvis to free the proximal and distal colon, respectively.Measure and record the length of the isolated colon. And use a 10 milliliter syringe equipped with a gavage needle to flush the colon with 10 milliliters of ice cold PBS to remove the feces and blood until the illuate runs clear. For histological identification, divide the tissue samples into equally sized proximal, middle, and distal sections.And fix the tissues in 4%paraformaldehyde overnight at 4 degrees Celsius. For hematoxylin and eosin staining of the isolated colon tissue, the next morning, submerge the tissue pieces in 30%sucrose and PBS overnight in individual 15 milliliter tubes for cryo protection of the samples. The next day, embedd the tissues in optimal cutting temperature or OCT compound.And cool the tissues in minus 20 degrees Celsius until the OCT hardens. Place the OCT blocks in the cryostat and set the thickness dial to 12 micrometers. Then slice and collect 12 micrometer thick frozen sections onto glass microscope slides.When all the tissues have been sectioned, warm the slides at 65 degrees Celsius on a hot plate for 20 minutes. And wash the heated sections briefly in distilled water before staining with hematoxylin staining solution for five minutes. Remove the excess hematoxylin solution and run in tap water for five minutes.And differentiate the sections with 0.5%hydrochloric acid in ethanol for 30 seconds, followed by a one minute rinse under running tap water. Next, wash the samples for one minute in PBS. Followed by another five minute wash under running tap water.At the end of the wash, submerge the tissues in an ascending ethanol series for 10 seconds per immersion. Followed by counterstaining in eosin for two minutes. For dehydration of the samples, submerge the slides in 95%ethanol and two changes of 100%ethanol for five minutes per immersion.Followed by clearing with two, five minute changes in xylene. Then score the tissue damage to the proximal, middle, and distal colons of each experimental group. For immunohistochemical analysis, after warming the sections for 20 minutes on the hot plate, wash the slides three times in PBS for 10 minutes per wash.And eliminate the endogenous peroxidase with a 10 minute 3%hydrogen peroxide incubation. At the end of the incubation, wash the samples three times in PBS as demonstrated and block any nonspecific binding with blocking buffer for at least one hour at room temperature. Then, replace the blocking buffer with the primary antibody cocktail of interest.For an overnight incubation at 4 degrees Celsius. The next morning, aspirate the excess primary antibody solution and wash the slides three times in PBS. After the last wash, incubate the slides with the appropriate biotinylated secondary antibody cocktail.Followed by labeling with streptavidin horseradish peroxidase complex at room temperature. To visualize the immunoreactive cells, label the samples with DAB until a light or dark brown color develops. And counterstain the sections with hematoxylin and 0.3%diluted ammonia.When the slides have dried, use a light microscope to obtain bright field images of the tissue sections under a 10x magnification. And use an image processing program to identify and quantify the population of the marked immune cells in both the epithelium and the lamina propria. For gene expression analysis in DSS treated colons, extract RNA from minus 80 degrees Celsius thawed colonic tissue samples according to standard RNA extraction protocols.And mix one microgram with the total RNA with 2.5 microliters of 20 millimolar oligo deoxythymidine 12 through 18 primers and one microliter of moloney murine leukemia virus reverse transcriptase. After a 60 minute incubation at 42 degrees Celsius, mix one microliter of the cDNA with 0.5%microliters of the appropriate forward and reverse quantitative PCR primers for the cytokines of interest and 2x fluorescent green dye. Then run the quantitative PCR under the appropriate parameters and calculate the relative gene expression according to standard protocols.Compared to wildtype mice, alpha gustducin knockout mice exhibit a more severe colitis with excessive weight loss, diarrhea and intestinal bleeding. After seven days of DSS administration, histological analysis of the colon sections reveal a more aggravated tissue damage within the proximal, middle, and distal colons of the knockout mice, compared to their wildtype counterparts. This excessive immune activation leads to the induction of colitis with a robust infiltration of various inflammatory cells in the knockout animal colon as observed by immunohistochemical analysis.Further, quantitative PCR analysis demonstrates higher levels of TNF alpha and inferon gamma expression but lower expression of IL-5, 10, and 13, in knockout compared to wildtype mouse colons with no difference in TGF beta one expression observed. While attempting this procedure, it's important to remember to optimize textorous southvater sodium dosage and demonstration duration. Forwarding this procedure, other method like obtaining culture can be performed in order to understand additional questions like the effect of inflammation in intestinal tissue origination.After it's development, this technique paves a way for researchers in the field of gut inflammation to explore the contributions of gene mutations to the severity of biodisease erodings and other vertebrates. Don't forget that working with disease gut tissue and its contents can be extremely hazardous and the repercussions such as wearing things that are appropriate, personal protection permanent should always be taken while performing this procedure.

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8.4K Views.  Zhejiang University. This method can help answer key questions in the inflammatory biodisease field about ulcerative colitis and Crohn's disease. The main advantage of this technique is that it can be used to evaluate first anti and proinfammatory effects of signaling proteins. The implication of this technique extends the survey of gas in new advances and inflammation.Though this method can provide insights into genetic effect on gut inflammation. It can also be applied to other factors such as diets and ...