This work was supported by a grant from the Pennsylvania Department of Health. 
Dr. Miguel Garcia Toscano was a postdoctoral Fellow at Temple University, funded by the Alfonso Martin Escudero Foundation during this study. 
We want to thank Iliya Yordanov and Kevin Kotredes for the making of the video.

1. Cecal Ligation and Puncture as a Mouse Model for Human Sepsis
For this procedure C57BL/6 mice (7-9 weeks old) are used.
<ol>
 <li>Anesthetize the mouse by injecting intraperitoneally a solution of 1:1 ketamine (75mg/kg) and xylazine (15mg/kg). As a reference, inject 30 &mu;l of the 1:1 solution into a mouse weighing 20 grams. Alternatively, mice can be anesthetized with inhaled isoflurane using an anesthetic vaporizer. </li>
 <li>Shave the abdomen of the mouse and disinfect area by first applying betadine solution followed by wiping with a 70% alcohol swab (number 1 in the picture sequence below). Chlorhexidine can be used as an alternative antiseptic. Optional: a sterile drape may be used to maintain the area clean.</li>
 <li>Under aseptic conditions, practice a 1 to 2 cm midline laparotomy and expose the cecum with adjoining intestine (2 and 3).</li>
 <li>The cecum is tightly ligated with a 6.0 silk suture (6-0 PROLENE, 8680G; Ethicon) at its base below the ileo-cecal valve, and is perforated once or twice with a 19-gauge needle (4 and 5) on the same side of the cecum. Please note that the length of ligated cecum defined as the distance from the distal end of cecum to ligation point will determine the degree of severity. A distance of &gt;1cm produces high grade sepsis while a distance of &le;1 cm produces mid-to-low grade sepsis. Also note that using the cecal perforation method shown here is different from the standard through and through puncture technique (introducing a needle through the cecum). Both methods reliably produce the same sepsis outcome. However, one disadvantage of the through and through technique is that it does not facilitate controlling the amount of feces extruded when the cecum is squeezed. </li>
 <li>The cecum is then gently squeezed to extrude a small amount of feces from the perforation sites (6). The cecum is returned to the peritoneal cavity and the 
 peritoneum is closed with 6.0 silk sutures. (7). </li>
 <li>The skin is closed with Reflex 7mm clips (RS-9258, Roboz Surgical Instruments) or Michel wound clips (7 mm, RS-9270) (8).</li>
 <li>Resuscitate mice by injecting subcutaneously 1 ml of pre-warmed 0.9% saline solution using a 25G needle. This fluid resuscitation measure will induce the 
 hyperdynamic phase of sepsis. This critical step is described further in the discussion section. </li>
 <li>Optional: Inject subcutaneously buprenorphine (0.05mg/ kg body weight) or tramadol (20mg/kg body weight) for post operative analgesia. Be advised that these opiates can suppress respiration and locomotion and these effects can be misinterpreted as signs of sepsis. </li>
 <li>The animals are placed temporarily on a heating pad or alternatively returned immediately to a cage with exposure to an infrared heating lamp of 150W until they recover from the anesthesia. The recovery time is from 30 min to 1 hour.</li>
 <li>Provide free access to food and water (hydrogel) placed on the bottom of the cage.</li>
 <li>Mice are monitored every 12 hours for survival for one to two weeks or euthanized at different time points for analysis of different parameters.</li>
</ol>
As control for the experimental design, sham animals would follow the laparotomy technique without ligation and puncture. 
 Six to 12 hours after the surgical procedure mice will become lethargic and develop fever, piloerection, diarrhea, huddling, and malaise; all the symptoms of sepsis. Mice with very severe sepsis can barely move prior to death and exhibit a dramatic decrease in body temperature. At this step mice should be euthanized to avoid prolonged pain and suffering.
<img src="/files/ftp_upload/2860/2860fig0.jpg" alt="Figure 0" />
2. Most Common Analyzed Parameters
To evaluate the outcome of the procedure, different parameters can be analyzed in organs, cell extracts or body fluids. Samples can be collected at different time points from 3 hours to one week after the surgical procedure. 
<ol>
 <li>Mice survival.</li>
 <li>Cytokines and chemokines in serum, peritoneal cavity and organ extracts.
 <ol>
 <li>Interleukin-6: Produced and released by monocytes, dendritic cells, macrophages, B cells, T cells, granulocytes, mast cells and many more cell types. It plays an important role in acute phase reaction and inflammation.</li>
 <li>Tumor necrosis factor-&#945;: Pleiotrophic cytokine that plays a central role in inflammation and apoptosis. Produced by monocytes, macrophages, neutrophils, dendritic cells and fibroblasts.</li>
 <li>nterleukin-1&#946;: Produced by monocytes, NK cells, dendritic cells, B cells and T cells. Induces fever and acute phase protein synthesis.</li>
 <li>Interleukin 10: Promotes phagocytic uptake and Th2 responses but suppresses antigen presentation and Th1 proinflammatory responses.</li>
 <li>Interleukin 10: Promotes phagocytic uptake and Th2 responses but suppresses antigen presentation and Th1 proinflammatory responses.</li>
 <li>Monocyte chemotactic protein-1 (also known as CCL2): Recruits monocytes, memory T cells, and dendritic cells to sites of tissue injury and infection.</li>
 <li>KC (CXCL1): Produced by macrophages and endothelial cells. Mouse KC is a potent neutrophil attractant and activator.</li>
 <li>RANTES: A monocyte chemoattractant. It can chemoattract unstimulated CD4+/CD45RO+ memory T cells and stimulated CD4+ and CD8+ T cells with na&#239;ve and memory phenotypes.</li>
 <li>Interferon-&#947;: Secreted by Th1 cells, cytotoxic T cells, dendritic cells and natural killer (NK) cells. Increases antigen presentation and lytic activity in macrophages and suppresses Th2 cell activity. Promotes adhesion and binding required for leukocyte migration and promotes NK cell activity. </li>
 <li>High-mobility group B-1 protein: In monocytes is a nuclear factor kappa B activator by binding to the cellular receptor for advance glycation end products (RAGE), activating the release of proinflammatory mediators in the late phase of sepsis. </li>
 </ol>
 </li>
 <li>Myeloperoxidase determination in organs as a measure of neutrophil infiltration. Myeloperoxidase (MPO) is a peroxidase enzyme most abundantly present in neutrophil granulocytes. It is a lysosomal protein stored in azurophilic granules of the neutrophil. MPO has a heme pigment, which causes its green color in secretions rich in neutrophils, such as pus and some forms of mucus.</li>
 <li>Bacteria load in organs and blood stream, measure as the number of colony forming units per milliliter. </li>
</ol>
3. Representative Results
The CLP procedure was initially performed in the C57BL/6 mouse strain. We tested several parameters to modulate the severity of sepsis by altering the length of the ligation and thickness of the needle as shown in Figures 1 and 2. Among these two factors, the length of the ligation seems to be more effective than the thickness of the needle to alter percent survival. As shown in Figure 1, increasing the length of the ligation by more than 1cm provokes an increase in mortality of 100% compared with mice having a ligation of &le;1cm. Increasing the thickness of the needle also decreased the percent survival from 100% (using a 22G needle) to 55% (using a 19G needle) with two punctures. We also tested the effect of CLP on C57BL/6 and 129SvJ mice to determine whether different mouse strains display similar or distinct susceptibility to CLP-induced sepsis. Figure 3 shows that under the same conditions, 129SvJ mice were more susceptible to infection than C57BL/6, indicated by an increased percent mortality.
<img src="/files/ftp_upload/2860/2860fig1.jpg" alt="Figure 1" /> 
 Figure 1. Effect of ligation length of the cecum in animal survival. CLP was performed in C57BL/6 mice using two different lengths of cecal ligation. This single parameter dramatically affects animal survival since all of the animals in the group with a ligation area longer than 1 cm died in less than 3 days when compared with a group of animals having a ligation area of 1 cm approx. (n=8).
<img src="/files/ftp_upload/2860/2860fig2.jpg" alt="Figure 2" /> 
 Figure 2. Influence of needle thickness on survival. CLP was performed in C57BL/6 mice using two different needle sizes, 19G and 22G. Mice with the cecum perforated using a 19G needle showed a 55-60% survival. In contrast, mice with the cecum perforated using a 22G needle showed 100% survival although they experienced typical symptoms of inflammation during the first 3-4 days; which disappeared after 4 days (n=8). 
<img src="/files/ftp_upload/2860/2860fig3.jpg" alt="Figure 3" /> 
 Figure 3. Comparison of sepsis susceptibility between two different mouse strains. The CLP model was performed in 129SvJ and C57BL/6 under the same conditions. At the end of the evaluation period the percent survival of the 129SvJ strain was 25% less than in the C57BL/6 strain, indicating a higher susceptibility to inflammation induced by polymicrobial infection. (n=6).

<ol>
	<li>Angus, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epidemiology+of+severe+sepsis+in+the+United+States:+analysis+of+incidence,+outcome,+and+associated+costs+of+care.">Epidemiology of severe sepsis in the United States: analysis of incidence, outcome, and associated costs of care.</a> Crit Care Med. 29, 1303-1310 (2001).</li><li>Riedemann, N. C., Guo, R. F., Ward, P. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+enigma+of+sepsis.">The enigma of sepsis.</a> J Clin Invest. 112, 460-467 (2003).</li><li>Eichacker, P. Q., Gerstenberger, E. P., Banks, S. M., Cui, X., Natanson, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Meta-analysis+of+acute+lung+injury+and+acute+respiratory+distress+syndrome+trials+testing+low+tidal+volumes.">Meta-analysis of acute lung injury and acute respiratory distress syndrome trials testing low tidal volumes.</a> Am J Respir Crit Care Med. 166, 1510-1514 (2002).</li><li>Buras, J. A., Holzmann, B., Sitkovsky, M. <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:+setting+the+stage.">Animal models of sepsis: setting the stage.</a> Nat Rev Drug Discov. 4, 854-865 (2005).</li><li>Doi, K., Leelahavanichkul, A., Yuen, P. S., Star, R. A. <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+and+sepsis-induced+kidney+injury.">Animal models of sepsis and sepsis-induced kidney injury.</a> J Clin Invest. 119, 2868-2878 (2009).</li><li>Godshall, C. J., Scott, M. J., Peyton, J. C., Gardner, S. A., Cheadle, W. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+background+determines+susceptibility+during+murine+septic+peritonitis.">Genetic background determines susceptibility during murine septic peritonitis.</a> J Surg Res. 102, 45-49 (2002).</li><li>De Maio, A., Torres, M. B., Reeves, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+determinants+influencing+the+response+to+injury,+inflammation,+and+sepsis.">Genetic determinants influencing the response to injury, inflammation, and sepsis.</a> Shock. 23, 11-17 (2005).</li><li>Diodato, M. D., Knoferl, M. W., Schwacha, M. G., Bland, K. I., Chaudry, I. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gender+differences+in+the+inflammatory+response+and+survival+following+haemorrhage+and+subsequent+sepsis.">Gender differences in the inflammatory response and survival following haemorrhage and subsequent sepsis.</a> Cytokine. 14, 162-169 (2001).</li><li>Turnbull, I. R. <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+age+on+mortality+and+antibiotic+efficacy+in+cecal+ligation+and+puncture.">Effects of age on mortality and antibiotic efficacy in cecal ligation and puncture.</a> Shock. 19, 310-313 (2003).</li><li>Miyaji, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ethyl+pyruvate+decreases+sepsis-induced+acute+renal+failure+and+multiple+organ+damage+in+aged+mice.">Ethyl pyruvate decreases sepsis-induced acute renal failure and multiple organ damage in aged mice.</a> Kidney Int. 64, 1620-1631 (2003).</li><li>Torres, M. B., De Maio, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+exaggerated+inflammatory+response+after+CLP+correlates+with+a+negative+outcome.">An exaggerated inflammatory response after CLP correlates with a negative outcome.</a> J Surg Res. 125, 88-93 (2005).</li><li>Doi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=AP214,+an+analogue+of+alpha-melanocyte-stimulating+hormone,+ameliorates+sepsis-induced+acute+kidney+injury+and+mortality.">AP214, an analogue of alpha-melanocyte-stimulating hormone, ameliorates sepsis-induced acute kidney injury and mortality.</a> Kidney Int. 73, 1266-1274 (2008).</li><li>Wilson, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluid+resuscitation+attenuates+early+cytokine+mRNA+expression+after+peritonitis.">Fluid resuscitation attenuates early cytokine mRNA expression after peritonitis.</a> J Trauma. 41, 622-627 (1996).</li><li>Zanotti-Cavazzoni, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluid+resuscitation+influences+cardiovascular+performance+and+mortality+in+a+murine+model+of+sepsis.">Fluid resuscitation influences cardiovascular performance and mortality in a murine model of sepsis.</a> Intensive Care Med. 35, 748-754 (2009).</li><li>Hugunin, K. M., Fry, C., Shuster, K., Nemzek, J. A. <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+tramadol+and+buprenorphine+on+select+immunologic+factors+in+a+cecal+ligation+and+puncture+model.">Effects of tramadol and buprenorphine on select immunologic factors in a cecal ligation and puncture model.</a> Shock. 34, 250-260 (2010).</li></ol>

Animal experiments were performed in accordance with the National Institute of Health Guide for Care and Use of Laboratory Animals, and approved by the animal care and use committee at Temple University.

Here we show in detail how to perform the CLP model in mice and modulate the grade of severity. 
Compared to other animal models of sepsis, CLP can be performed in any mouse strain of different age and sex. It is a relatively easy and inexpensive surgical procedure. In this model, the grade of severity has a direct impact on the percentage of survival. The length of the ligation, the thickness of the needle and the number of punctures are parameters that can be controlled to modulate the sev...

<table border="1">
	<tbody>
		<tr>
			<th>Name of the reagent</th>
			<th>Company</th>
			<th>Catalogue number</th>
			<th>Comments</th>
		</tr>
		<tr>
			<td>Ketamine</td>
			<td>Ketaset</td>
			<td>0856-2013-01</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Xylazine</td>
			<td>AnaSed</td>
			<td>NADA# 139-236</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Insulin syringe 29G</td>
			<td>Exel</td>
			<td>26028</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Silk suture, 6-0 PROLENE</td>
			<td>Ethicon</td>
			<td>8680G</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>19G and 25G Needle</td>
			<td>BD</td>
			<td>305186</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Shaver</td>
			<td>General supply</td>
			<td>General supply</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Infrared Heating lamp</td>
			<td>General supply</td>
			<td>General supply</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Michel wound clips 7mm</td>
			<td>Roboz Surgical Instr</td>
			<td>RS-9270</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Ear Loop Mask</td>
			<td>Fisher Scientific</td>
			<td>19-130-4181</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Dissection scissors</td>
			<td>Roboz Surgical Instr</td>
			<td>RS-6702</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Betadine solution</td>
			<td>VWR</td>
			<td>63410-992</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Surgical forceps</td>
			<td>Roboz Surgical Instr</td>
			<td>RS-5135</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>70% Isopropyl alcohol pad</td>
			<td>Fisher Scientific</td>
			<td>22-031-350</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Buprenorphine</td>
			<td>Bedford Labs</td>
			<td>55390-100-10</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Tramadol</td>
			<td>Sigma-Aldrich</td>
			<td>42965</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

cecal ligation puncture procedure

Human sepsis is characterized by a set of systemic reactions in response to intensive and massive infection that failed to be locally contained by the host. Currently, sepsis ranks among the top ten causes of mortality in the USA intensive care units 1. During sepsis there are two established haemodynamic phases that may overlap. The initial phase (hyperdynamic) is defined as a massive production of proinflammatory cytokines and reactive oxygen species by macrophages and neutrophils that affects vascular permeability (leading to hypotension), cardiac function and induces metabolic changes culminating in tissue necrosis and organ failure. Consequently, the most common cause of mortality is acute kidney injury. The second phase (hypodynamic) is an anti-inflammatory process involving altered monocyte antigen presentation, decreased lymphocyte proliferation and function and increased apoptosis. This state known as immunosuppression or immune depression sharply increases the risk of nocosomial infections and ultimately, death. The mechanisms of these pathophysiological processes are not well characterized. Because both phases of sepsis may cause irreversible and irreparable damage, it is essential to determine the immunological and physiological status of the patient. This is the main reason why many therapeutic drugs have failed. The same drug given at different stages of sepsis may be therapeutic or otherwise harmful or have no effect 2,3. To understand sepsis at various levels it is crucial to have a suitable and comprehensive animal model that reproduces the clinical course of the disease. It is important to characterize the pathophysiological mechanisms occurring during sepsis and control the model conditions for testing potential therapeutic agents. 
To study the etiology of human sepsis researchers have developed different animal models. The most widely used clinical model is cecal ligation and puncture (CLP). The CLP model consists of the perforation of the cecum allowing the release of fecal material into the peritoneal cavity to generate an exacerbated immune response induced by polymicrobial infection. This model fulfills the human condition that is clinically relevant. As in humans, mice that undergo CLP with fluid resuscitation show the first (early) hyperdynamic phase that in time progresses to the second (late) hypodynamic phase. In addition, the cytokine profile is similar to that seen in human sepsis where there is increased lymphocyte apoptosis (reviewed in 4,5). Due to the multiple and overlapping mechanisms involved in sepsis, researchers need a suitable sepsis model of controlled severity in order to obtain consistent and reproducible results.

Watch this Scientific Journal Video about Cecal Ligation Puncture Procedure at JoVE.com

Cecal Ligation Puncture Procedure

The mouse model of cecal ligation and puncture as a valuable tool for the study of human sepsis.

Human sepsis is characterized by a set of systemic reactions in response to intensive and massive infection that failed to be locally contained by the ...

Research

JoVE Journal

Medicine

54.5K Views.  Temple University. Il modello murino di legatura del cieco e la puntura come un prezioso strumento per lo studio della sepsi umana.

Video: Cecal Ligation Puncture Procedure

The C-seal: A Biofragmentable Drain Protecting the Stapled Colorectal Anastomosis from Leakage

Colorectal anastomotic leakage (AL) is a serious complication in colorectal surgery leading to high morbidity and mortality rates1. The incidence of AL varies between 2.5 and 20% 2-5. Over the years, many strategies aimed at lowering the incidence of anastomotic leakage have been examined6, 7. 
The cause of AL is probably multifactorial. Etiological factors include insufficient arterial blood supply, tension on the anastomosis, hematoma and/or infection at the anastomotic site, and co-morbid factors of the patient as diabetes and atherosclerosis8. Furthermore, some anastomoses may be insufficient from the start due to technical failure.
Currently a new device is developed in our institute aimed at protecting the colorectal anastomosis and lowering the incidence of AL. This so called C-seal is a biofragmentable drain, which is stapled to the anastomosis with the circular stapler. It covers the luminal side of the colorectal anastomosis thereby preventing leakage.
The C-seal is a thin-walled tube-like drain, with an approximate diameter of 4 cm and an approximate length of 25 cm (figure 1). It is a tubular device composed of biodegradable polyurethane. Two flaps with adhesive tape are found at one end of the tube. These flaps are used to attach the C-seal to the anvil of the circular stapler, so that after the anastomosis is made the C-seal can be pulled through the anus. The C-seal remains in situ for at least 10 days. Thereafter it will lose strength and will degrade to be secreted from the body together with the gastrointestinal natural contents.
The C-seal does not prevent the formation of dehiscences. However, it prevents extravasation of faeces into the peritoneal cavity. This means that a gap at the anastomotic site does not lead to leakage.
Currently, a phase II study testing the C-seal in 35 patients undergoing (colo-)rectal resection with stapled anastomosis is recruiting. The C-seal can be used in both open procedures as well as laparoscopic procedures. The C-seal is only applied in stapled anastomoses within 15cm from the anal verge. In the video, application of the C-seal is shown in an open extended sigmoid resection in a patient suffering from diverticular disease with a stenotic colon.

The C-seal is a biofragmentable drain protecting the stapled colorectal anastomosis. In this video, details of the manufacturing, deployment and use are shown.

Colorectal anastomotic leakage (AL) is a serious complication in colorectal surgery leading to high morbidity and mortality rates1. The incidence of AL ...

Cecal Ligation and Puncture-induced Sepsis as a Model To Study Autophagy in Mice

Experimental sepsis can be induced in mice using the cecal ligation and puncture (CLP) method, which causes polymicrobial sepsis. Here, a protocol is provided to induce sepsis of varying severity in mice using the CLP technique. Autophagy is a fundamental tissue response to stress and pathogen invasion. Two current protocols to assess autophagy in vivo in the context of experimental sepsis are also presented here. (I) Transgenic mice expressing green fluorescence protein (GFP)-LC3 fusion protein are subjected to CLP. Localized enhancement of GFP signal (puncta), as assayed either by immunohistochemical or confocal assays, can be used to detect enhanced autophagosome formation and, thus, altered activation of the autophagy pathway. (II) Enhanced autophagic vacuole (autophagosome) formation per unit tissue area (as a marker of autophagy stimulation) can be quantified using electron microscopy. The study of autophagic responses to sepsis is a critical component of understanding the mechanisms by which tissues respond to infection. Research findings in this area may ultimately contribute towards understanding the pathogenesis of sepsis, which represents a major problem in critical care medicine.

Experimental sepsis can be induced in mice using the cecal ligation and puncture (CLP) method. Current protocols to assess autophagy in vivo in the context of CLP-induced sepsis are presented here: A protocol for measuring autophagy using (GFP)-LC3 mice, and a protocol for measuring autophagosome formation by electron microscopy.

Experimental sepsis can be induced in mice using the cecal ligation and puncture (CLP) method, which causes polymicrobial sepsis. Here, a protocol is ...

Immunology and Infection

Catheterization of Intestinal Loops in Ruminants

The intestine is a complex structure that is involved not only in absorption of nutrients, but also acts as a barrier between the individual and the outside world. As such, the intestine plays a pivotal role in immunosurveillance and protection from enteric pathogens. Investigating intestinal physiology and immunology commonly employs 'intestinal loops' as an experimental model. The majority of these loop models are non-recovery surgical procedures that study short-term (&lt;24 hr) changes in the intestine (1-3). We previously created a recovery intestinal loop model to specifically measure long-term (&lt;6 mo) immunological changes in the intestine of sheep following exposure to vaccines, adjuvants, and viruses (4). This procedure localized treatments to a specific 'loop', allowing us to sample this area of the intestine. A significant drawback of this method is the single window of opportunity to administer treatments (i.e. at the time of surgery). Furthermore, samples of both the intestinal mucosa and luminal contents can only be taken at the termination of the project. Other salient limitations of the above model are that the surgical manipulation and requisite post-operative measures (e.g. administration of antibiotics and analgesics) can directly affect the treatment itself and/or alter immune function, thereby confounding results. Therefore, we modified our intestinal loop model by inserting long-term catheters into the loops. Sheep recover fully from the procedure, and are unaffected by the exteriorized catheters. Notably, the establishment of catheters in loops allows us to introduce multiple treatments over an extended interval, following recovery from surgery and clearance of drugs administered during surgery and the post-operative period.

We describe a novel surgical method for catheterizing 'intestinal loops' within the ileum of sheep. Once animals have recovered from surgery and have cleared antibiotics and analgesics, multiple treatments can be deposited directly in loops via the catheters.

The intestine is a complex structure that is involved not only in absorption of nutrients, but also acts as a barrier between the individual and the ...

Biology

Long-Term Catheterization of the Intestinal Lymph Trunk and Collection of Lymph in Neonatal Pigs

Catheterization of the intestinal lymph trunk in neonatal pigs is a technique allowing for the long-term collection of large quantities of intestinal (central) efferent lymph. Importantly, the collection of central lymph from the intestine enables researchers to study both the mechanisms and lipid constitutes associated with lipid metabolism, intestinal inflammation and cancer metastasis, as well as cells involved in immune function and immunosurveillance. A ventral mid-line surgical approach permits excellent surgical exposure to the cranial abdomen and relatively easy access to the intestinal lymph trunk vessel that lies near the pancreas and the right ventral segment of the portal vein underneath the visceral aspect of the right liver lobe. The vessel is meticulously dissected and released from the surrounding fascia and then dilated with sutures allowing for insertion and subsequent securing of the catheter into the vessel. The catheter is exteriorized and approximately 1 L/24 hr of lymph is collected over a 7 day period. While this technique enables the collection of large quantities of central lymph over an extended period of time, the success depends on careful surgical dissection, tissue handling and close attention to proper surgical technique. This is particularly important with surgeries in young animals as the lymph vessels can easily tear, potentially leading to surgical and experimental failure. The video demonstrates an excellent surgical technique for the collection of intestinal lymph.

We present a surgical procedure to catheterize the intestinal lymph trunk in neonatal pigs to collect large quantities of lipid metabolism components from efferent lymph.

Catheterization of the intestinal lymph trunk in neonatal pigs is a technique allowing for the long-term collection of large quantities of intestinal ...

Use of a Central Venous Line for Fluids, Drugs and Nutrient Administration in a Mouse Model of Critical Illness

This protocol describes a centrally catheterized mouse model of prolonged critical illness. We combine the cecal ligation and puncture method to induce sepsis with the use of a central venous line for fluids, drugs and nutrient administration to mimic the human clinical setting. Critically ill patients require intensive medical support in order to survive. While the majority of patients will recover within a few days, about a quarter of the patients need prolonged intensive care and are at high risk of dying from non-resolving multiple organ failure. Furthermore, the prolonged phase of critical illness is hallmarked by profound muscle weakness, and endocrine and metabolic changes, of which the pathogenesis is currently incompletely understood. The most widely used animal model in critical care research is the cecal ligation and puncture model to induce sepsis. This is a very reproducible model, with acute inflammatory and hemodynamic changes similar to human sepsis, which is designed to study the acute phase of critical illness. However, this model is hallmarked by a high lethality, which is different from the clinical human situation, and is not developed to study the prolonged phase of critical illness. Therefore, we adapted the technique by placing a central venous catheter in the jugular vein allowing us to administer clinically relevant supportive care, to better mimic the human clinical situation of critical illness. This mouse model requires an extensive surgical procedure and daily intensive care of the animals, but it results in a relevant model of the acute and prolonged phase of critical illness.

This protocol describes a centrally catheterized mouse model of prolonged critical illness. We combine the cecal ligation and puncture method to induce sepsis with the use of a central venous line for fluids, drugs and nutrient administration to mimic the human clinical setting.

This protocol describes a centrally catheterized mouse model of prolonged critical illness. We combine the cecal ligation and puncture method to induce ...

Design of Cecal Ligation and Puncture and Intranasal Infection Dual Model of Sepsis-Induced Immunosuppression

Sepsis, a severe and complicated life-threatening infection, is characterized by an imbalance between pro- and anti-inflammatory responses in multiple organs. With the development of therapies, most patients survive the hyperinflammatory phase but progress to an immunosuppressive phase, which increases the emergence of secondary infections. Therefore, improved understanding of the pathogenesis underlying secondary hospital-acquired infections in the immunosuppressive phase during sepsis is of tremendous importance. Reported here is a model to test infectious outcomes by creating double-hit infections in mice. A standard surgical procedure is used to induce polymicrobial peritonitis by cecal ligation and puncture (CLP) and followed by intranasal infection of Staphylococcus aureus to simulate pneumonia occurring in immune suppression that is frequently seen in septic patients. This dual model can reflect the immunosuppressive state occurring in patients with protracted sepsis and susceptibility to secondary infection from nosocomial pneumonia. Hence, this model provides a simple experimental approach to investigate the pathophysiology of sepsis-induced secondary bacterial pneumonia, which may be used for discovering novel treatments for sepsis and its complications.

This protocol describes techniques to measure infectious outcomes underlying secondary hospital-acquired infections in the immunosuppressive condition, first by establishing cecal ligation/puncture mice then challenging them with intranasal infection to create a clinically relevant model of immunosuppression sepsis.

Sepsis, a severe and complicated life-threatening infection, is characterized by an imbalance between pro- and anti-inflammatory responses in multiple ...

An In Vivo Method for Evaluating the Gut-Blood Barrier and Liver Metabolism of Microbiota Products

The gut-blood barrier (GBB) controls the passage of nutrients, bacterial metabolites and drugs from intestinal lumen to the bloodstream. The GBB integrity is disturbed in gastrointestinal, cardiovascular and metabolic diseases, which may result in easier access of biologically active compounds, such as gut bacterial metabolites, to the bloodstream. Thus, the permeability of the GBB may be a marker of both intestinal and extraintestinal diseases. Furthermore, the increased penetration of bacterial metabolites may affect the functioning of the entire organism.
Commonly used methods for studying the GBB permeability are performed ex vivo. The accuracy of those methods is limited, because the functioning of the GBB depends on intestinal blood flow. On the other hand, commonly used in vivo methods may be biased by liver and kidney performance, as those methods are based on evaluation of urine or/and peripheral blood concentrations of exogenous markers. Here, we present a direct measurement of GBB permeability in rats using an in vivo method based on portal blood sampling, which preserves intestinal blood flow and is virtually not affected by the liver and kidney function. 
Polyurethane catheters are inserted into the portal vein and inferior vena cava just above the hepatic veins confluence. Blood is sampled at baseline and after administration of a selected marker into a desired part of the gastrointestinal tract. Here, we present several applications of the method including (1) evaluation of the colon permeability to TMA, a gut bacterial metabolite, (2) evaluation of liver clearance of TMA, and (3) evaluation of a gut-portal blood-liver-peripheral blood pathway of gut bacteria-derived short-chain fatty acids. Furthermore, the protocol may also be used for tracking intestinal absorption and liver metabolism of drugs or for measurements of portal blood pressure.

An In Vivo Method for Evaluating the Gut-Blood Barrier and Liver Metabolism of Microbiota Products

The access of nutrients, microbiota metabolites and medicines to the circulation is controlled by the gut-blood barrier (GBB). We describe a direct method for measuring the GBB permeability in vivo, which, in contrast to commonly used indirect methods, is virtually not affected by liver and kidney functions.

The gut-blood barrier (GBB) controls the passage of nutrients, bacterial metabolites and drugs from intestinal lumen to the bloodstream. The GBB integrity ...

Evaluation of a Reliable Biomarker in a Cecal Ligation and Puncture-Induced Mouse Model of Sepsis

Sepsis is a severe life-threatening and rapidly developing disease that causes millions of deaths annually worldwide. Researchers have made tremendous efforts to elucidate the pathophysiology of sepsis using various animal models; the mouse model of sepsis induced by cecal ligation and puncture (CLP) is widely used in laboratories. The three technical aspects that affect the severity and replicability of the CLP model are the percentage of cecum ligated, the size of the needle used for cecal puncture, and the volume of feces squeezed into the abdominal cavity. The rapid and specific diagnosis of sepsis is a crucial factor that affects the outcome. The gold standard for sepsis diagnosis is microbial culture; however, this process is time-consuming and sometimes inaccurate. The detection of sepsis-specific biomarkers is fast, but the existing biomarkers are unsatisfactory due to a short half-life, non-specificity, and insufficient sensitivity. Therefore, there is an urgent need for a reliable biomarker of sepsis in the early stages. Previous publications suggest that excessive neutrophil extracellular traps (NETs) occur in sepsis. Citrullinated histone H3 (CitH3), as a NET component, is elevated both in septic animals and patients, and the presence of CitH3 is a reliable diagnostic biomarker of sepsis. The present study aimed to describe a standardized mouse model of CLP-induced sepsis and establish a reliable blood biomarker of sepsis. Our work may contribute to the early and accurate diagnosis of sepsis in the future.

This protocol presents the operative details of cecal ligation and puncture (CLP) in a mouse model of sepsis. CLP is one of the most widely used techniques to create an animal model of sepsis. Therefore, a standardized CLP protocol is required for the attainment of reliable research results.

Sepsis is a severe life-threatening and rapidly developing disease that causes millions of deaths annually worldwide. Researchers have made tremendous ...

Laparoscopic Non-Mesh Cerclage Pectopexy for Pelvic Organ Prolapse

Pelvic organ prolapse (POP) is widespread among the female population and significantly impairs the patient's quality of life. It is important to restore apical support for treating POP. Sacrocolpopexy and pectopexy are indicated for apical prolapse. Using a synthetic mesh in these techniques increases success by enhancing apical support. However, the implantation of synthetic mesh is associated with mesh-related complications. In addition, the exorbitant cost of synthetic mesh and lack of universal access limit the popularity of these procedures. The current study develops a unique technique known as laparoscopic non-mesh cerclage pectopexy (LNMCP), in which permanent cervical cerclage sutures are embedded in the round ligament until the iliopectineal ligament. The iliopectineal ligament was sutured, resulting in a firm cervical suspension. The procedure was successfully performed in 16 cases in the hospital. The surgical duration was 67.8 min &plusmn; 15.5 min, and the blood loss was 73.1 mL &plusmn; 51.1 mL. No procedural complications were seen. LNMCP is associated with an objective success rate of 100% and a subjective success rate of 93.8%. LNMCP for patients with apical prolapse obviates the need for a mesh, thereby avoiding complications associated with mesh erosion and reducing medical costs. In addition, it is easy to perform even in resource-poor areas without access to synthetic mesh.

The present pilot study describes the development of laparoscopic non-mesh cerclage pectopexy to treat pelvic organ prolapse. The procedure can be used to prevent any complications associated with the use of mesh.

Pelvic organ prolapse (POP) is widespread among the female population and significantly impairs the patient's quality of life. It is important to restore ...

Generation of Mouse Proximal Colon Loop Model: A Surgical Procedure to Generate Proximal Colon Loop and Measure Intestinal Permeability by Detection of Fluorescent Markers in Serum Following Intraluminal Injection

Source: Boerner, K. et al. <a href="https://www.jove.com/v/62093">Functional Assessment of Intestinal Permeability and Neutrophil Transepithelial Migration in Mice using a Standardized Intestinal Loop Model.</a> J. Vis. Exp. (2021).
In this video, we describe a surgical procedure to generate mouse proximal colon loop or pcLoop segment followed by intraluminal injection of fluorescent markers into the segment to study the intestinal epithelial permeability.