JHN is supported by the Swiss National Foundation (SNSF 310030_146290).

Mice were bred and kept under specific pathogen-free (SPF) conditions in the animal facility of Department of Biomedicine, University of Basel (Basel, Switzerland). All mouse experiments were performed in accordance with the Swiss Federal and Cantonal regulations (animal protocol number 2816 [Canton of Basel-Stadt]).
1. Preparation of LPS Solution
<ol>
	<li>Open the stock of LPS purified from Escherichia coli 0111:B4 under sterile conditions and reconstitute it in water to the conce...

<ol>
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T., 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=Mutations+in+NOD2+are+associated+with+fibrostenosing+disease+in+patients+with+Crohn's+disease.">Mutations in NOD2 are associated with fibrostenosing disease in patients with Crohn's disease.</a> Gastroenterology. 123, 679-688 (2002).</li><li>Liu, Y., 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=Immunocytochemical+evidence+of+Listeria,+Escherichia+coli,+and+Streptococcus+antigens+in+Crohn's+disease.">Immunocytochemical evidence of Listeria, Escherichia coli, and Streptococcus antigens in Crohn's disease.</a> Gastroenterology. 108, 1396-1404 (1995).</li><li>Schaffer, T., 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=Anti-Saccharomyces+cerevisiae+mannan+antibodies+(ASCA)+of+Crohn's+patients+crossreact+with+mannan+from+other+yeast+strains,+and+murine+ASCA+IgM+can+be+experimentally+induced+with+Candida+albicans.">Anti-Saccharomyces cerevisiae mannan antibodies (ASCA) of Crohn's patients crossreact with mannan from other yeast strains, and murine ASCA IgM can be experimentally induced with Candida albicans.</a> Inflamm Bowel Dis. 13, 1339-1346 (2007).</li><li>Sellon, R. K., 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=Resident+enteric+bacteria+are+necessary+for+development+of+spontaneous+colitis+and+immune+system+activation+in+interleukin-10-deficient+mice.">Resident enteric bacteria are necessary for development of spontaneous colitis and immune system activation in interleukin-10-deficient mice.</a> Infect Immun. 66, 5224-5231 (1998).</li><li>Gkouskou, K. K., Deligianni, C., Tsatsanis, C., Eliopoulos, A. 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P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=C-type+lectin+SIGN-R1+has+a+role+in+experimental+colitis+and+responsiveness+to+lipopolysaccharide.">C-type lectin SIGN-R1 has a role in experimental colitis and responsiveness to lipopolysaccharide.</a> J Immunol. 184, 2627-2637 (2010).</li><li>Spadoni, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+gut-vascular+barrier+controls+the+systemic+dissemination+of+bacteria.">A gut-vascular barrier controls the systemic dissemination of bacteria.</a> Science. 350, 830-834 (2015).</li><li>Balmer, M. L., 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=The+liver+may+act+as+a+firewall+mediating+mutualism+between+the+host+and+its+gut+commensal+microbiota.">The liver may act as a firewall mediating mutualism between the host and its gut commensal microbiota.</a> Sci Transl Med. 6, 237ra266 (2014).</li><li>Maier, R. V., Mathison, J. C., Ulevitch, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interactions+of+bacterial+lipopolysaccharides+with+tissue+macrophages+and+plasma+lipoproteins.">Interactions of bacterial lipopolysaccharides with tissue macrophages and plasma lipoproteins.</a> Prog Clin Biol Res. 62, 133-155 (1981).</li><li>Lu, Y. C., Yeh, W. C., Ohashi, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=LPS/TLR4+signal+transduction+pathway.">LPS/TLR4 signal transduction pathway.</a> Cytokine. 42, 145-151 (2008).</li><li>Deng, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lipopolysaccharide+clearance,+bacterial+clearance,+and+systemic+inflammatory+responses+are+regulated+by+cell+type-specific+functions+of+TLR4+during+sepsis.">Lipopolysaccharide clearance, bacterial clearance, and systemic inflammatory responses are regulated by cell type-specific functions of TLR4 during sepsis.</a> J Immunol. 190, 5152-5160 (2013).</li><li>Kagan, J. 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=TRAM+couples+endocytosis+of+Toll-like+receptor+4+to+the+induction+of+interferon-beta.">TRAM couples endocytosis of Toll-like receptor 4 to the induction of interferon-beta.</a> Nat Immunol. 9, 361-368 (2008).</li><li>Akira, S., Uematsu, S., Takeuchi, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathogen+recognition+and+innate+immunity.">Pathogen recognition and innate immunity.</a> Cell. 124, 783-801 (2006).</li><li>Cohen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+immunopathogenesis+of+sepsis.">The immunopathogenesis of sepsis.</a> Nature. 420, 885-891 (2002).</li><li>Suffredini, A. F., 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=Effects+of+recombinant+dimeric+TNF+receptor+on+human+inflammatory+responses+following+intravenous+endotoxin+administration.">Effects of recombinant dimeric TNF receptor on human inflammatory responses following intravenous endotoxin administration.</a> J Immunol. 155, 5038-5045 (1995).</li><li>Fink, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+sepsis.">Animal models of sepsis.</a> Virulence. 5, 143-153 (2014).</li><li>Poltorak, 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=Defective+LPS+signaling+in+C3H/HeJ+and+C57BL/10ScCr+mice:+mutations+in+Tlr4+gene.">Defective LPS signaling in C3H/HeJ and C57BL/10ScCr mice: mutations in Tlr4 gene.</a> Science. 282, 2085-2088 (1998).</li><li>Hoshino, K., 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=Cutting+edge:+Toll-like+receptor+4+(TLR4)-deficient+mice+are+hyporesponsive+to+lipopolysaccharide:+evidence+for+TLR4+as+the+Lps+gene+product.">Cutting edge: Toll-like receptor 4 (TLR4)-deficient mice are hyporesponsive to lipopolysaccharide: evidence for TLR4 as the Lps gene product.</a> J Immunol. 162, 3749-3752 (1999).</li><li>Corral, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+lipopolysaccharide+and+cecal+ligation+and+puncture+on+blood+coagulation+and+inflammation+in+sensitive+and+resistant+mice+models.">Role of lipopolysaccharide and cecal ligation and puncture on blood coagulation and inflammation in sensitive and resistant mice models.</a> Am J Pathol. 166, 1089-1098 (2005).</li><li>Shrum, B., 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+robust+scoring+system+to+evaluate+sepsis+severity+in+an+animal+model.">A robust scoring system to evaluate sepsis severity in an animal model.</a> BMC Res Notes. 7, 233 (2014).</li><li>Brandwein, S. L., 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=Spontaneously+colitic+C3H/HeJBir+mice+demonstrate+selective+antibody+reactivity+to+antigens+of+the+enteric+bacterial+flora.">Spontaneously colitic C3H/HeJBir mice demonstrate selective antibody reactivity to antigens of the enteric bacterial flora.</a> J Immunol. 159, 44-52 (1997).</li><li>Macpherson, A. J., McCoy, K. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardised+animal+models+of+host+microbial+mutualism.">Standardised animal models of host microbial mutualism.</a> Mucosal Immunol. 8, 476-486 (2015).</li><li>Masopust, D., Sivula, C. P., Jameson, S. 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This protocol mimics immunological processes that occur after the invasion by microbial-derived products. Critical steps within the protocol are the selection of the mouse line, the hygiene status of the mice, the dose of LPS, the monitoring of the animals for the occurrence of endotoxemia, and the time point of experiment termination. Most importantly, the genetic background of the mouse strain has to be considered. Different mouse strains have different susceptibility to LPS. For example, the C3H/HeJ and C57BL/10ScCr m...

An erratum was issued for: <a href="https://www.jove.com/video/57610/injections-lipopolysaccharide-into-mice-to-mimic-entrance-microbial">Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach</a>
One of the authors&#39; names was corrected from:
Katarina Raduolovic
to:
Katarina Radulovic

An erratum was issued for: <a href="https://www.jove.com/video/57610/injections-lipopolysaccharide-into-mice-to-mimic-entrance-microbial">Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach</a>.&#160;An author name was updated.

Erratum: Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach

The human intestine is colonized with a large consortium of microorganisms that forms the microbiota, who has developed a mutually beneficial relationship with the host during the evolution. In this relationship, the host provides a secure niche for the microbiota, whereas the microbiota provides vitamins, nutrient digestion and protection from pathogens to the host, where the microbiota resides1. When this beneficial relationship between the host and the microbiota is disturbed, diseases can develop, such as inflammatory bowel disease (IBD). IBD is a multifactorial chronic inflammatory disease of the intestine caused by genetic and environmental factors that occur in two major forms, Crohn&#39;s disease (CD) and ulcerative colitis (UC). Despite similarities between the two IBD forms, they are characterized by certain differences in the location and nature of inflammatory modifications. CD is a relapsing transmural inflammatory disorder that can potentially extend to any part of the gastrointestinal tract, while UC is non-transmural and is restricted to the colon. Furthermore, mutations in Nucleotide-binding oligomerization domain-containing protein 2 (NOD2), a pattern recognition receptor (PRR) that recognizes muramyl dipeptide (MDP), a component of the cell wall of most Gram-positive and - negative bacteria, is associated with CD2. Furthermore, Escherichia coli (E. coli), Listeria and Streptococci and their products were all found within macrophages in CD patients that have entered the host after a barrier breach3. When bacteria or their products enter the host during the development of CD, the immune system develops a response leading to the production of circulating anti-bacterial antibodies4. Maybe, the most convincing evidence for the role of the microbiota in the pathogenesis of IBD stems from mouse models. When animals are treated with antibiotics, or when mice are kept in germ-free (GF) conditions, the severity of the disease is reduced in most colitis models, such as in IL-10-/- mice that do not develop colitis in GF facilities5,6. Furthermore, colitis also disturbs the composition of the microbiota, which is characterized by an imbalanced composition and reduced richness called dysbiosis7. The consequence of IBD can be an increased intestinal permeability that can lead to the entrance of microbes and microbial-derived products into the host.
In animals, the application of Dextran Sodium Sulfate (DSS) induces an intestinal epithelial breach leading to an increased permeability of the epithelial barrier8. Portal LPS concentrations are elevated in animals with DSS colitis9. Interestingly, animals lacking the C type lectin receptor specific intracellular adhesion molecule-3 grabbing nonintegrin homolog-related 1 (SIGN-R1) are protected from DSS colitis and LPS-induced endotoxemia10. To further disseminate into the host, bacteria or bacteria derived products have to pass the vascular barrier11, the peritoneal cavity, in which the small and large intestine is located, the mesenteric lymph nodes and/or the liver12. To reduce the complexity of this system, a defined bacterial-derived compound was used. LPS, which causes endotoxemia after intraperitoneal (i.p.) or intravenous (i.v.) injection13 was injected into mice, to study the expression of the interleukins Il6 and Ilb and the cytokine Tnfa in response to LPS.
LPS is a pathogen-associated molecular pattern (PAMP) expressed as a cell-wall component of Gram-negative bacteria, that consists of lipid A (the main PAMP in the structure of LPS), a core oligosaccharide and an O side chain14. Toll-like receptor 4 (TLR4) expressed by dendritic cells, macrophages, and epithelial cells recognizes LPS15, that requires co-receptors for appropriate binding. The acute phase protein LPS-binding protein (LBP) binds LPS to form a complex that transfers LPS to the cluster of differentiation 14 (CD14), a glycosylphosphatidylinositol-anchored membrane protein. CD14 further shuttles LPS to Lymphocyte antigen 96 or also known as MD-2, which is associated with the extracellular domain of TLR4. The binding of LPS to MD-2 facilitates the dimerization of TLR4/MD-2 to induce conformational changes to recruit intracellular adaptor molecules to activate the downstream signaling pathway14, which includes the myeloid differentiation primary response gene 88 (MyD88)-dependent pathway and the TIR domain-containing adaptor-inducing interferon-&#946; (TRIF)-dependent pathway16. The recognition of LPS by TLR4 then activates the NF-&#954;B pathway and induces the expression of proinflammatory cytokines, such as TNF&#945;, IL-6, and IL-1&#946;17.
In particular, when LPS is injected into animals, the concentration of LPS given to the animals, the genetic background of the animal and the diet has to be considered. High concentrations of LPS leads to a septic shock, characterized by hypotension and multiple organ failures, and finally to death18. Mice are less sensitive to LPS compared to humans, where LPS concentrations between 2-4 ng/kg body weight (BW) are able to induce a cytokine storm19. For mice, the lethal dose (LD50), which induces death in half of the mice ranges from 10-25 mg/kg BW20 depending on the mouse strain used. For the commonly used mouse strains, C57Bl/6 and BALB/c, the lethal dose 50% (LD50) is 10 mg/kg BW. In contrast, the strains C3H/HeJ and C57BL/10ScCr are protected from LPS induced endotoxemia, which is due to mutations in Tlr421. Consequently, Tlr4-deficient mice are hyporesponsive to injections with LPS22. Other genetically modified mouse lines, such as PARP1-/- mice23 are resistant to LPS-induced toxic shock.
The mouse model described here uses a sublethal dose of LPS administered systemically to mimic the consequences of LPS dissemination after a barrier breach of the body`s surfaces. The chosen LPS concentration (2 mg/kg BW) did not induce mortality in C56Bl/6 mice, but the induced release of pro-inflammatory cytokines.

<table border="0" cellpadding="0" cellspacing="0" width="896">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">DreamTaq Green PCR Master Mix (2x)</td>
			<td style="width:303px;">Thermo Fisher Scientific, Waltham, MA, USA</td>
			<td style="width:119px;">K1081</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">High Capacity cDNA Reverse Transcription Kit,</td>
			<td style="width:303px;">Applied Biosystems, Foster City, CA, USA</td>
			<td>4368813</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RNase-Free DNase Set,</td>
			<td>Qiagen, Hilden, Germany</td>
			<td>79254</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LPS Escherichia coli O111:B4</td>
			<td>Invivogen, San Diego, CA, USA.</td>
			<td>tlrl-eblps</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Omnican 50 Single-use insulin syringe</td>
			<td>B. Braun Melsungen, Melsungen, Germany</td>
			<td>9151125</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bioanalyzer 2100</td>
			<td>Agilent Technologie, Santa Clara, USA</td>
			<td style="width:119px;">not applicable</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge 5430</td>
			<td>Eppendorf, Hamburg, Germany</td>
			<td style="width:119px;">not applicable</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge Mikro 220R</td>
			<td>Hettich, Kirchlengern, Germany</td>
			<td style="width:119px;">not applicable</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dissection tools</td>
			<td>Aesculap, Tuttlingen, Germany</td>
			<td style="width:119px;">not applicable</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fast-Prep-24 5G Sample Preparation System</td>
			<td>M.P. Biomedicals, Santa Ana, CA, USA</td>
			<td style="width:119px;">not applicable</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NanoDrop ND-1000</td>
			<td>NanoDrop Products, Wilmington, DE, USA</td>
			<td style="width:119px;">not applicable</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TRI Reagent</td>
			<td>Zymo Research, Irvine, CA, USA</td>
			<td>R2050-1</td>
			<td></td>
		</tr>
	</tbody>
</table>

injections of lipopolysaccharide into mice to mimic entrance of microbial-derived products after intestinal barrier breach

The intestinal epithelial barrier separates the host from the microbiota that is normally tolerated or ignored. The breach of this barrier results in the entrance of bacteria or bacteria-derived products into the host, accessing the host circulation and inner organs leading to the uncontrolled inflammation as observed in patients with inflammatory bowel disease (IBD), that are characterized by an increased intestinal epithelial permeability.
To mimic the entrance of bacterial-derived compounds into the host, an endotoxemia model has been adopted in which lipopolysaccharide (LPS), a component of the outer cell wall of Gram-negative bacteria, were injected into mice. In this study, a sublethal dose of LPS was intraperitoneally injected and the mice were subsequently monitored for 8 h using a disease score. Furthermore, the expression levels of the inflammatory cytokines Il6, Il1b, and Tnfa were analyzed in the spleen, liver and colon by qPCR at different time points post LPS injection. This model could be useful for the studies involving investigation of immune responses after the invasion of microorganisms or bacterial-derived products caused by a barrier breach of body surfaces.

To mimic the consequences for the host after the entrance of bacteria or bacterial-derived products that occurs after intestinal barrier breach, LPS was injected into C57Bl/6 mice in a sublethal dose (2 &#181;g/g body weight). Every single mouse was monitored and scored for the occurrence of endotoxemia with parameters listed in score sheet that includes, the appearance of the mice, the activity of the animals, the condition of eyes, and the respiration rate and quality (Table 1</...

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Injections of Lipopolysaccharide into Mice to Mimic Entrance of Microbial-derived Products After Intestinal Barrier Breach

Here a protocol to mimic the entrance of bacterial-derived compounds after intestinal barrier breach is presented. A low sublethal dose of lipopolysaccharide was injected systemically into mice, which were monitored for 24 h post-injection. The expression of pro-inflammatory cytokines was determined at several time points in spleen, liver, and colon.

The intestinal epithelial barrier separates the host from the microbiota that is normally tolerated or ignored. The breach of this barrier results in the ...

The overall goal of this experiment is to present a model that mimics the entrance of microbial-derived products after an intestinal barrier breach. This model can be used to investigate immune responses after invasion of microorganisms. This method can help answer key questions in the inflammatory bowel disease field, such as uncontrolled inflammation, which is characterized by an increased intestinal epithelial permeability.The main advantage of this technique is that it not only uses a defined pump, but is also an uncomplicated approach that does not require surgery and can be used in every laboratory setting. Demonstrating the procedure will be myself, Rachel Mak'Anyengo, a postdoc, and Berna Kaya, a PhD student. Handle the mouse gently but firmly, and restrain the animal in one hand.Ensure that the mouse is securely held and can breathe normally. Tilt the mouse nose slightly towards the floor to expose the abdomen for injection. Locate the midline of the abdomen and inject the volume of LPS required on the lower-left or right side.It is very important to ensure that the needle enters the peritoneal cavity to avoid misinjections. The needle should also not go too deep into the peritoneal cavity to avoid injury of inner organs. Gently return the animal to the home cage.Monitor the mice for the occurrence and severity of endotoxemia at the time of injection and every two hours thereafter for eight hours. Record observations in the attached score sheet. Prepare the collection tubes by adding one milliliter of single-step RNA isolation reagent to two milliliter tubes pre-filled with 1.4 millimeter ceramic spheres.After euthanizing and ensanguinating the mouse, use a pair of scissors to cut the skin and the muscle layer, exposing the abdominal cavity with the inner organs. Carefully dissect the spleen, liver, and colon. Clean the fat from each organ, then place in PBS on ice.Next, use scissors or a scalpel to cut a 0.5 centimeter long piece from each organ. Briefly dry the tissue on a piece of paper tissue, and place it in the collection tube, making sure it is completely immersed in RNA isolation reagent. Then homogenize the tissue in a high-speed benchtop homogenizer.For soft tissues like spleen, liver and colon, use one cycle of homogenization at high speed for 30 seconds. After homogenization, incubate the samples for five minutes at room temperature. Carefully immerse the tubes in liquid nitrogen to snap freeze the tissue lysate.Store the snap-frozen lysate at minus 80 degrees Celsius until RNA isolation. Begin RNA isolation by thawing the frozen tissue lysate on ice. Once thawed, centrifuge the sample at 1000 times G for five minutes at four degrees Celsius to pellet the remaining tissue particles that might be left.Following centrifugation, transfer the supernatants to a new, nuclease-free 1.5 milliliter tube, and add 200 microliters of ice-cold chloroform per one milliliter of RNA isolation reagent. Immediately shake the gristly for 10 to 15 seconds. After incubating the samples for two to three minutes at room temperature, centrifuge at 12, 000 times G for 15 minutes at four degrees Celsius.The sample will now contain three phases, the lower red phenol chloroform phase, the interphase, and the upper colorless aqueous phase. Collect the RNA-containing upper aqueous phase and transfer into a new, nuclease-free 1.5 milliliter tube. To precipitate the RNA, add 0.5 milliliters of ice-cold isopropanol per one milliliter of RNA isolation reagent, and mix gently by inverting the tube five to six times.After incubating for 10 to 15 minutes at room temperature, centrifuge at 12, 000 times G for 10 minutes at four degrees Celsius. Following centrifugation, completely remove the supernatant containing the isopropanol without disturbing the pellet. Then wash the pellets with one milliliter of ice-cold 75%ethanol per one milliliter of RNA isolation reagent used for the initial lysis, and vortex the sample briefly.After centrifuging the sample at 7500 or 12, 000 times G for five minutes at four degrees Celsius, completely remove the supernatant without disturbing the pellet. Leave the opened tubes under the chemical hood for three to five minutes to air-dry the RNA pellet at room temperature. Next, dissolve the RNA pellet in 20 to 50 microliters of nuclease-free water by pipetting carefully up and down.Then incubate the sample at 55 degrees Celsius for 10 to 15 minutes to further improve the solution of the RNA. Digest contaminating DNA by first adding nuclease-free water to a maximum of 10 micrograms of RNA so that the final volume will be 50 microliters after the addition of buffer and enzyme. Then add five microliters of 10X DNase 1 buffer and one microliter of recombinant DNase 1 per sample and mix gently by pipetting up and down.Incubate at 37 degrees Celsius for 20 to 30 minutes. Following the incubation, vortex the DNase in activation reagent, then add five microliters to the sample and mix well. Incubate for five minutes at room temperature, mixing occasionally by hand.After centrifuging at 10, 000 times G for one and a half minutes, transfer the supernatant containing the DNA-free RNA into a new, nuclease-free tube. Finally, measure the RNA concentration and quality by spectrophotometer. After injection of LPS, the disease score, which includes assessments of the appearance and activity of the animals, opening of their eyes, and their respiration rate and quality, was plotted on the Y axis against time on the X axis.QPCR to quantify cytokine expression revealed that Il6 peaked two hours after LPS injection in spleen and colon, and four hours after injection in the liver. The expression of Il1 beta, Tnf alpha, and Il10 peaked four hours after injection in all tissues. Within eight hours, the expression of Il6, Il1 beta, Tnf alpha and Il10 returned to baseline levels.While attempting the procedure, it's important to remember to consider the dose of LPS, the hygiene status of the mice, the time point of the experiment termination and most importantly, the genetic background of the mouse strain. After watching this video, you should have a good understanding of how to mimic the entrance of bacterial-derived compounds into a host after a barrier breach. The low, sublethal dose of LPS systematically injected into mice induces upregulation of proinflammatory cytokines, which are quantified by RGQ PCR analysis.

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19.1K vistas.  University of Basel. The overall goal of this experiment is to present a model that mimics the entrance of microbial-derived products after an intestinal barrier breach. This model can be used to investigate immune responses after invasion of microorganisms. This method can help answer key questions in the inflammatory bowel disease field, such as uncontrolled inflammation, which is characterized by an increased intestinal epithelial permeability.The main advantage of this technique is that it not only use...