Animal Model Of Peritonitis Research Articles

Probiotic Properties of Alcaligenes faecalis Isolated from Argyrosomus regius in Experimental Peritonitis\xa0(Rat Model)

A strain of Alcaligenes faecalis A12C (A. faecalis A12C) isolated from Argyrosomus regius is a probiotic in fish. Previous experiments showed that A. faecalis A12C had inhibitory effects on the growth of multidrug-resistant bacteria. We aimed to confirm whether A. faecalis A12C is safe and has adequate intestinal colonization in experimental rats, and evaluate its efficacy in an animal model of peritonitis. We used 30 male rats, randomly divided into 6 groups (n = 5): three groups (HA7, HA15, HA30) received A. faecalis A12C in drinking water (6 × 108 CFU/mL) for 7 days, and three control groups received drinking water only. All groups were evaluated at 7, 15, and 30 days. Survival after A. faecalis A12C administration was 100% in all groups. Mild eosinophilia (1.5%, p < 0.01) and increased aspartate aminotransferase (86 IU/L, p < 0.05) were observed in HA7, followed by progressive normalization. No histological signs of organ injury were found. We observed significant E. coli decline in faeces, parallel to an increase in A. faecalis A12C at 7 days. E. coli had a tendency to recover initial values, while A. faecalis A12C disappeared from the intestinal microbiota at 30 days. To evaluate its efficacy against peritonitis, we studied two additional groups of animals: IA group pretreated with A. faecalis A12C before E. coli intra-abdominal inoculation, and IC group inoculated with no A. faecalis A12C. We found an increase in C-reactive protein, alanine aminotransferase, urea, and eosinophils in IC animals when compared with IA. Peritonitis was more evident in IC than in IA animals. Our findings suggest that A. faecalis A12C altered clinically relevant parameters in sepsis and was associated with a lesser spread of infection.

PLK4 deubiquitination by Spata2-CYLD suppresses NEK7-mediated NLRP3 inflammasome activation at the centrosome.

The innate immune sensor NLRP3 assembles an inflammasome complex with NEK7 and ASC to activate caspase-1 and drive the maturation of proinflammatory cytokines IL-1β and IL-18. NLRP3 inflammasome activity must be tightly controlled, as its over-activation is involved in the pathogenesis of inflammatory diseases. Here, we show that NLRP3 inflammasome activation is suppressed by a centrosomal protein Spata2. Spata2 deficiency enhances NLRP3 inflammasome activity both in the macrophages and in an animal model of peritonitis. Mechanistically, Spata2 recruits the deubiquitinase CYLD to the centrosome for deubiquitination of polo-like kinase 4 (PLK4), the master regulator of centrosome duplication. Deubiquitination of PLK4 facilitates its binding to and phosphorylation of NEK7 at Ser204. NEK7 phosphorylation in turn attenuates NEK7 and NLRP3 interaction, which is required for NLRP3 inflammasome activation. Pharmacological or shRNA-mediated inhibition of PLK4, or mutation of the NEK7 Ser204 phosphorylation site, augments NEK7 interaction with NLRP3 and causes increased NLRP3 inflammasome activation. Our study unravels a novel centrosomal regulatory pathway of inflammasome activation and may provide new therapeutic targets for the treatment of NLRP3-associated inflammatory diseases.

Hematopoietic Stem/Progenitor Cell Dependent Participation of Innate Lymphoid Cells in Low-Intensity Sterile Inflammation.

Hematopoietic stem/progenitor cells (HSPC) are characterized by their unique capacities of self-renewal and multi-differentiation potential. This second property makes them able to adapt their differentiation profile depending on the local environment they reach. Taking advantage of an animal model of peritonitis, induced by injection of the TLR-2 ligand, zymosan, we sought to study the relationship between bone marrow-derived hematopoietic stem/progenitor cells (BM-HSPCs) and innate lymphoid cells (ILCs) regarding their emergence and differentiation at the site of inflammation. Our results demonstrate that the strength of the inflammatory signals affects the capacity of BM-derived HSPCs to migrate and give rise in situ to ILCs. Both low- and high-dose of zymosan injections trigger the appearance of mature ILCs in the peritoneal cavity where the inflammation occurs. Herein, we show that only in low-dose injected mice, the recovered ILCs are dependent on an in situ differentiation of BM-derived HSPCs and/or ILC2 precursors (ILC2P) wherein high-dose, the stronger inflammatory environment seems to be able to induce the emergence of ILCs independently of BM-derived HSPCs. We suggest that a relationship between HSPCs and ILCs seems to be affected by the strength of the inflammatory stimuli opening new perspectives in the manipulation of these early hematopoietic cells.

Homeostatic regulation of T cell trafficking by a B cell-derived peptide is impaired in autoimmune and chronic inflammatory disease.

During an inflammatory response, lymphocyte recruitment into tissue must be tightly controlled because dysregulated trafficking contributes to the pathogenesis of chronic disease. Here we show that during inflammation and in response to adiponectin, B cells tonically inhibit T cell trafficking by secreting a peptide (PEPITEM) proteolytically derived from 14.3.3.ζδ protein. PEPITEM binds cadherin-15 on endothelial cells, promoting synthesis and release of sphingosine-1 phosphate, which inhibits trafficking of T cells without affecting recruitment of other leukocytes. Expression of adiponectin receptors on B cells and adiponectin induced PEPITEM secretion wanes with age, implying immune senescence of the pathway. Additionally, these changes are evident in individuals with type-1-diabetes or rheumatoid arthritis, and circulating PEPITEM in patient serum is reduced compared to healthy age matched donors. In both diseases, tonic inhibition of T cell trafficking across inflamed endothelium is lost. Importantly, control of patient T cell trafficking is re-established by exogenous PEPITEM. Moreover, in animal models of peritonitis, hepatic I/R injury, Salmonella infection, Uveitis and Sjögren’s Syndrome, PEPITEM could reduce T cell recruitment into inflamed tissues.

Nanotechnology and adeno-associated virus-based decorin gene therapy ameliorates peritoneal fibrosis.

Peritoneal dialysis (PD) is a life-sustaining therapy for end-stage renal disease (ESRD), used by 10-15% of the dialysis population worldwide. Peritoneal fibrosis (PF) is a known complication of long-term PD and frequently follows episodes of peritonitis, rendering the peritoneal membrane inadequate for dialysis. Transforming growth factor (TGF)-β is an inducer of fibrosis in several tissues and organs, and its overexpression has been correlated with PF. Animal models of peritonitis have shown an increase in expression of TGF-β in the peritoneal tissue. Decorin, a proteoglycan and component of the extracellular matrix, inactivates TGF-β, consequently reducing fibrosis in many tissues. Recently, gold nanoparticles (GNP) have been used for drug delivery in a variety of settings. In the present study, we tested the possibility that GNP-delivered decorin gene therapy ameliorates zymosan-mediated PF. We created a PF model using zymosan-induced peritonitis. Rats were treated with no decorin, GNP-decorin, or adeno-associated virus-decorin (AAV-decorin) and compared with controls. Tissue samples were then stained for Masson's trichrome, enface silver, and hematoxylin and eosin, and immunohistochemistry was carried out with antibodies to TGF-β1, α-smooth muscle actin (α-SMA), and VEGF. Animals which were treated with GNP-decorin and AAV-decorin gene therapy had significant reductions in PF compared with untreated animals. Compared with untreated animals, the treated animals had better preserved peritoneal mesothelial cell size, a significant decrease in peritoneal thickness, and decreased α-SMA. Quantitative PCR measurements showed a significant decrease in the peritoneal tissue levels of α-SMA, TGF-β, and VEGF in treated vs. untreated animals. This study shows that both GNP-delivered and AAV-mediated decorin gene therapies significantly decrease PF in vivo in a rodent model. This approach has important clinical translational potential in providing a therapeutic strategy to prevent PF in PD patients.

Lack of effect of dopaminergic antagonists in a rodent model of peritoneal sepsis

Central nervous system dopaminergic mechanisms have been implicated in the cytokine response to stress and sepsis. We here describe the effects of haloperidol or clozapine in the treatment of sepsis induced by cecal ligation and puncture. Male Wistar rats were subjected to the CLP procedure were treated with haloperidol or clozapine and plasma cytokines, myeloperoxidase activity, markers of organ injury and survival was analyzed. The addition of haloperidol or clozapine to basic support did not diminished hepatic, renal, pancreatic or muscular damage observed after sepsis. Neither haloperidol, nor clozapine, modulates pro and antiinflammatory cytokines after sepsis induction. In addition, haloperidol treatment did not diminished myeloperoxidase activity in the kidney, lung or liver, or altered BALF markers of lung damage or inflammatory infiltration. Our data did not support a role of haloperidol or clozapine as an immunomodulator agent in the treatment of sepsis in an animal model of peritonitis.

Influence of laparoscopy and laparotomy on gasometry, leukocytes and cytokines in a rat abdominal sepsis model

Laparoscopic surgery is associated with reduced surgical trauma, and less acute phase response, as compared with open surgery. Cytokines are important regulators of the biological response to surgical and anesthetic stress. The aim of this study was to determine if CO2 pneumoperitoneum would change cytokine expression, gas parameters and leukocyte count in septic rats. Wistar rats were randomly assigned to five groups: control (anesthesia only), laparotomy, CO2 pneumoperitoneum, cecum ligation and puncture by laparotomy, and laparoscopic cecum ligation and puncture. After 30 min of the procedures, arterial blood samples were obtained to determine leukocytes subpopulations by hemocytometer. TNFalpha, IL-1beta, IL-6 were determined in intraperitoneal fluid (by ELISA). Gas parameters were measured on arterial blood, intraperitoneal and subperitoneal exudates. Peritoneal TNFalpha, IL-1beta and IL-6 concentrations were lower in pneumoperitoneum rats than in all other groups (p<0.05). TNFalpha, IL-1beta and IL-6 expression was lower in the laparoscopic than in laparotomic sepsis (p<0.05). Rats from laparoscopic cecum ligation and puncture group developed significant hypercarbic acidosis in blood and subperitoneal fluid when compared to open procedure group. Total white blood cells and lymphocytes were significantly lower in laparoscopic cecum ligation and puncture rats than in the laparotomic (p<0.01). Nevertheless, the laparotomic cecum ligation rats had a significant increase in blood neutrophils and eosinophils when compared with controls (p<0.05). This study demonstrates that the CO2 pneumoperitoneum reduced the inflammatory response in an animal model of peritonitis with respect to intraperitoneal cytokines, white blood cell count and clinical correlates of sepsis. The pneumoperitoneum produced hypercarbic acidosis in septic animals.

Effect of carbon dioxide pneumoperitoneum on bacteraemia and endotoxaemia in an animal model of peritonitis

Effect of carbon dioxide pneumoperitoneum on bacteraemia and endotoxaemia in an animal model of peritonitis

Effect of carbon dioxide pneumoperitoneum on bacteraemia and endotoxaemia in an animal model of peritonitis.

Laparoscopy is increasingly used in conditions complicated by peritonitis. A theoretical concern is that carbon dioxide pneumoperitoneum may increase bacteraemia. This study examines the effect of carbon dioxide pneumoperitoneum on bacteraemia, endotoxaemia and physiological correlates of sepsis in an animal model of peritonitis. New Zealand white rabbits were assigned to three groups of six animals. Group 1 received an intraperitoneal inoculation of 10(9) colony-forming units of Escherichia coli followed by a 10-cm midline laparotomy. Group 2 received an identical bacterial inoculum followed by a 12-mmHg carbon dioxide pneumoperitoneum for 1 h. Group 3 received no bacteria but had a 12-mmHg carbon dioxide pneumoperitoneum for 1 h. Groups 1 and 2 had significantly higher levels of bacteraemia (P < 0.01) and endotoxaemia (P < 0.01) accompanied by significantly lower mean arterial pressures (P < 0.05) and higher heart rates (P < 0.05) compared with group 3. After 6 h groups 1 and 2 were significantly hypocarbic (P < 0.01), leucopenic (P < 0.01) and thrombocytopenic (P < 0.01). There was no difference between group 1 and group 2. A carbon dioxide pneumoperitoneum of 12 mmHg does not increase bacteraemia or endotoxaemia, nor does it adversely affect physiological or laboratory correlates of sepsis compared with laparotomy in this animal model of peritonitis.

Effects of Pneumoperitoneum on Hemodynamic and Systemic Immunologic Responses to Peritonitis in Pigs

Background. Experimental evidence supporting the safety of laparoscopic intervention during sepsis is limited. The purpose of this study was to evaluate the effects of pneumoperitoneum on immunologic and hemodynamic responses to peritoneal sepsis. Materials and methods. A porcine model of peritonitis was created using an intraperitoneal autologous fecal inoculum. Pigs were then subjected to one of four procedures 24 h postinoculation ( n = 6 per group): laparotomy, CO 2 laparoscopy, helium laparoscopy, and anesthesia only (1.5% isoflurane in 100% O 2, mechanical ventilation). Venous blood samples were obtained prior to inoculation, and at 24 (prior to procedure), 30, 48, 72, and 96 h postinoculation to determine white blood count (WBC) with differential, C-reactive protein (CRP), tumor necrosis factor, and bacteremia. Heart rate, end-tidal CO 2 (ETCO 2), mean arterial blood pressure (MAP), and arterial blood gas variables were also measured at baseline and every 30 min throughout the procedure. Results. Postoperative blood cultures confirmed systemic bacteremia in all groups at all time periods postinoculation. Following inoculation, WBC, band cell count, and CRP remained elevated above baseline in all groups throughout the study ( P < 0.01). However, no significant differences in these parameters were observed among groups. In the CO 2 laparoscopy group, MAP, ETCO 2, and arterial pCO 2 were increased above baseline, while pH was decreased throughout the procedure ( P < 0.01). Conclusion. In this animal model of peritonitis, CO 2 pneumoperitoneum induced hypercapnia, acidemia, and systemic hypertension intraoperatively, without a discernable effect on systemic immune function.

Effect of CO(2) insufflation on bacteremia and bacterial translocation in an animal model of peritonitis.

The widespread adoption of the laparoscopic approach has created some concern over the potential for increased risk of bacteremia and sepsis due to increased intraabdominal pressure in patients with intraabdominal infection and peritonitis. This study examines the effect of the CO(2) pneumoperitoneum on bacteremia and bacterial translocation. New Zealand white rabbits were assigned into three groups of 10 animals. In group 1, 100 ml of sterile saline was infused into the peritoneal cavity under 10 mmHg CO(2) insufflation for 1 h. Group 2 received 100 ml of saline containing 10(9) CFU/ml (colony-forming units) E. coli strain 0163 and 10 mmHg CO(2) insufflation for 1 h. Group 3 received an identical bacterial inoculum, followed by a 10-cm midline laparotomy. Blood samples were taken for culture by cardiac puncture at various intervals during the experiment. At 6 h after being subjected to the experimental procedures, the rabbits were killed and their organs were cultured quantitatively for translocating bacteria. In group 1, neither blood nor organ cultures were positive, whereas in group 2 all blood cultures became positive in 1 h, and intraperitoneally infused bacteria translocated to the lung and kidney in all rabbits. In group 3, blood cultures became positive in 1 h, all but two of the rabbits had translocated bacteria in their lungs, and kidney samples from two of the rabbits were culture-positive. Our results indicate that both CO(2) pneumoperitoneum and laparotomy increase the incidence of bacterial translocation from the peritoneal cavity into the bloodstream. Thus, the risk of translocation to extraperitoneal organs such as lung and kidney is increased significantly by laparoscopy. Therefore, laparoscopic surgery should be avoided or used cautiously in the setting of acute peritonitis.

Granulocyte colony-stimulating factor and antibiotics in the prophylaxis of a murine model of polymicrobial peritonitis and sepsis.

Infections that occur after intraabdominal surgery still cause considerable morbidity and mortality despite the administration of prophylactic antibiotics. Increasing the number of neutrophils may also be a prophylactic approach, and granulocyte colony-stimulating factor (G-CSF) has been found to be beneficial in different animal models of peritonitis and sepsis. It is the combination of G-CSF and antibiotics, however, that is clinically relevant. Treatment of mice with G-CSF that was started before cecal ligation and puncture and continued afterward with antibiotics improved survival, decreased splenic bacterial colony-forming units and serum tumor necrosis factor, and increased serum interleukin-10, compared with treatment with antibiotics alone or with saline. Compared with saline, antibiotics alone increased tumor necrosis factor and did not affect interleukin-10. Thus, G-CSF confers onto antibiotics beneficial antiinfectious and antiinflammatory properties. A prophylactic regimen combining G-CSF and antibiotics may help prevent severe infectious complications following intraabdominal surgery.

Increased systemic inflammation after laparotomy vs laparoscopy in an animal model of peritonitis.

To study the influence of laparotomy and laparoscopy on local and systemic inflammation in a rat model of peritonitis. Bacteremia, peripheral leukocyte subpopulations, tumor necrosis factor alpha (TNF-alpha) plasma levels, and ex vivo secretion of peripheral blood mononuclear cells were investigated after laparotomy and laparoscopy in a prospective randomized experimental study. Surgical department of a university hospital. 60 male inbred Wistar rats. Standardized fecal inoculum was injected intraperitoneally and rats underwent laparotomy (n=20), laparoscopy (n=20), or no further manipulation (control group, n=20). Blood samples were obtained during the perioperative course to determine bacteremia, leukocytic subpopulations, TNF-alpha plasma levels, and ex vivo secretion. The number of intraperitoneal abscesses was determined in each animal after 1 week. The hypothesis of the experiment was that laparoscopy with carbon dioxide leads to an increase of local and systemic inflammation in comparison with the laparotomy and control groups. One hour after intervention, bacteremia was significantly higher in the laparotomy and laparoscopy groups compared with the control group (P=.01). Fecal inoculum caused significant monocytopenia and lymphocytopenia in all groups within 1 hour after intervention (P<.05), with complete recovery on day 2 only in the laparoscopy and control groups. Laparotomy caused a significant increase in TNF-alpha plasma levels and decrease of ex vivo production of TNF-alpha compared with the other 2 groups (P<.05). Laparotomy and laparoscopy increased the incidence of bacteremia and systemic inflammation in this peritonitis model. The inflammatory response was significantly higher in the laparotomy group compared with the laparoscopy group.

Does laparoscopy increase bacteremia and endotoxemia in a peritonitis model?

Laparoscopy is increasingly used in patients with intraabdominal bacterial infection although pneumoperitoneum may increase bacteremia by elevated intraabdominal pressure. The influence of laparotomy and laparoscopy on bacteremia, endotoxemia, and postoperative abscess formation was investigated in a rat model. Rats received intraperitoneally a standardized fecal inoculum and underwent laparotomy (n = 20), or laparoscopy (n = 20), or no further manipulation in the control group (n = 20). Bacteremia and endotoxemia were higher after laparotomy and laparoscopy compared to the control group (p = 0.01) 1 h after intervention. One hour after intervention, aerobic and anaerobic bacterial species were detected in the laparotomy group while only anaerobic bacteria were found in the other two groups. Although bacteremia and endotoxemia did not differ among the three groups after 1 week, the mean number of intraperitoneal abscesses was significantly higher (p < 0.05) after laparotomy (n = 10) compared with laparoscopy (n = 6) and control group (n = 5). Laparoscopy does not increase bacteremia and intraperitoneal abscess formation compared to laparotomy in an animal model of peritonitis.

Pentoxifylline improves intracellular electrolytes in sepsis

Sepsis is associated with a generalised membrane dysfunction leading to an increase in intracellular sodium, chlorid, and water. The decrease in extracellular water is thought to act as a nonosmotic stimulus to the secretion of antidiuretic hormone. The resultant hyponatraemia is associated with increased surgical morbidity and mortality. Treatment aimed at improving intracellular electrolytes may improve surgical morbidity and mortality. An animal model of peritonitis was used to evaluate the effect of pentoxifylline. Previously, this dimethyl xanthine derivative was shown to stabilise the cell membrane. Administration of pentoxifylline significantly lowered intracellular sodium and chloride, particularly when given after caecal ligation and puncture. This may have clinical implications in the treatment and prevention of hyponatraemia.

A New Model for Studying Nutrition in Peritonitis

In guinea pigs fed ad libitum, controlled intraperitoneal infusion of bacteria by an implanted 7-day osmotic pump resulted in peritonitis or abscess formation with a 50% survival 14-18 days after pump implantation. Administration of 125 kcal/kg/day of a diet found to be optimal for burned guinea pigs by continuous pump controlled feedings via a previously placed gastrostomy was well-tolerated, with a 62.5% mortality by Day 17. Administration of only 100 kcal/kg/day caused weight loss of approximately 17% after 16 days, but fewer animals died (42.8%, p = NS). Feeding either 150 kcal/kg/day or 175 kcal/kg/day caused death in all 25 animals (p less than 0.001) and their survival time was slightly shortened (p = NS) when compared with animals receiving 100 or 125 kcal/kg/day. This is the first animal model of peritonitis that permits incisive dissection of the relative influences of dietary composition on outcome, because survival can be extended to 2 weeks or more in the presence of continuing sepsis.