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PubMed2004

Splanchnic oxygen transport, hepatic function and gastrointestinal barrier after normothermic cardiopulmonary bypass.

BACKGROUND: The effect of non-pulsatile, normothermic cardiopulmonary-bypass (CPB) on the splanchnic blood-flow and oxygen-transport, the hepatic function and the gastrointestinal barrier were observed in a prospective observational study in 31 adults undergoing cardiac valve replacement surgery. METHODS: The splanchnic (i.e. hepatic) blood-flow (HBF) was measured by the constant infusion of indocyanine-green (ICG) using a hepatic-venous catheter. Liver function was examined by calculation of lactate uptake, ICG extraction and the monoethylglycinexylidide (MEGX) test. A day before and after surgery the gastrioduodenal and intestinal permeability was measured by determination of sucrose and lactulose/mannitol excretion. RESULTS: Splanchnic blood flow and oxygen delivery did not decrease during and after surgery while splanchnic oxygen consumption (P < 0.0125) and arterial lactate concentrations increased. The splanchnic lactate uptake paralleled the lactate concentration. After but not during CPB an increase of systemic oxygen consumption was observed. The MEGX test values decreased on the first day after surgery. The ICG extraction was attenuated during the operation. The gastroduodenal and the intestinal permeability increased significantly postoperatively (P < 0.002, respectively, P < 0.001). There was no correlation between these findings and the duration of CPB. There was a significant correlation of the intestinal permeability but not of the gastroduodenal permeability between the prior and after surgery values (P < 0.001). CONCLUSION: Increased oxygen consumption during CPB may indicate an inflammatory reaction due to the pump beginning in the splanchnic area or a redistribution of the splanchinc blood flow during the CPB. Normothermic CPB does not lead to a significant or prolonged reduction of liver function. Normothermic CPB causes an increase of gastrointestinal permeability. The intestinal barrier function prior to surgery was accountable for the degree of loss of intestinal barrier function following surgery.

Adult↗
PubMed1992

Increased transcellular permeability of rat small intestine after thermal injury.

The pathway which results in a loss of intestinal barrier function and transepithelial transfer of macromolecules after cutaneous thermal injury is unknown. To determine the enhanced absorption pathway, transepithelial transport of horseradish peroxidase (HRP) was examined ultrastructurally after a thermal injury. Within 6 h after the injury, increased HRP uptake was seen in the portal and systemic blood with the maximal increase in uptake measured at 18 h postinjury; permeability returned to normal by 72 h postinjury. Morphologically, the increased uptake was found to be transcellular through ultrastructurally normal intestinal absorptive cells. Occasional focal regions of enhanced HRP uptake were found and this enhanced uptake was attributed to focal intestinal epithelial disruptions. This increase in intestinal permeability represents a transient loss of intestinal barrier function and potentially allows absorption of macromolecules such as endotoxin from the intestinal lumen into the portal circulation early after thermal injury.

Animals↗
PubMed1998

Studies on the risk assessment of Listeria monocytogenes.

Humans are frequently exposed to Listeria monocytogenes, and high numbers may be ingested during consumption of certain types of food. However, epidemiological investigations show that listeriosis is a rare disease. Risk assessment studies using an animal mouse model indicate that almost all L. monocytogenes serovars present in food have clear virulent properties. The intravenous dose causing infection in 50% (IV ID50) of mice not previously exposed to L. monocytogenes (nonprotected mice) was 1.8 log(10) units. For mice previously exposed to L.monocytogenes (immunologically protected mice was >9.0 log10 5.6 log(10) units. The ID(50) of orally exposed nonprotected mice amounted to 6.5 log10 units, and no significant effects of type of food (water/milk) and storage time at 5 degrees C (milk) were observed. The oral ID50 of immunologically protected mice was >9.0 log10 units. Furthermore, there was approximately 1-2 log10 difference between the ID50 and the lethal dose causing death in 50% (LD50). The results show that both the intestinal barrier and the specific immune defense mechanism are highly effective in preventing infection of mice orally exposed to L.monocytogenes. Delaying the immune defense had no effect on the protective activity of the intestinal barrier, indicating that these protective mechanisms independently. The risk assessment results obtained in the mouse model support the epidemiological finding that listeriosis is a rare disease in humans, despite frequent exposure to the organism.

Animals↗
PubMed2002

Recovery of ischaemic injured porcine ileum: evidence for a contributory role of COX-1 and COX-2.

BACKGROUND: We have previously shown that the non-selective cyclooxygenase (COX) inhibitor indomethacin retards recovery of intestinal barrier function in ischaemic injured porcine ileum. However, the relative role of COX-1 and COX-2 elaborated prostaglandins in this process is unclear. AIMS: To assess the role of COX-1 and COX-2 elaborated prostaglandins in the recovery of intestinal barrier function by evaluating the effects of selective COX-1 and COX-2 inhibitors on mucosal recovery and eicosanoid production. METHODS: Porcine ileal mucosa subjected to 45 minutes of ischaemia was mounted in Ussing chambers, and transepithelial electrical resistance was used as an indicator of mucosal recovery. Prostaglandins E1 and E2 (PGE) and 6-keto-PGF1alpha (the stable metabolite of prostaglandin I2 (PGI2)) were measured using ELISA. Thromboxane B2 (TXB2, the stable metabolite of TXA2) was measured as a likely indicator of COX-1 activity. RESULTS: Ischaemic injured tissues recovered to control levels of resistance within three hours whereas tissues treated with indomethacin (5x10(-6) M) failed to fully recover, associated with inhibition of eicosanoid production. Injured tissues treated with the selective COX-1 inhibitor SC-560 (5x10(-6) M) or the COX-2 inhibitor NS-398 (5x10(-6) M) recovered to control levels of resistance within three hours, associated with significant elevations of PGE and 6-keto-PGF1alpha compared with untreated tissues. However, SC-560 significantly inhibited TXB2 production whereas NS-398 had no effect on this eicosanoid, indicating differential actions of these inhibitors related to their COX selectivity. CONCLUSIONS: The results suggest that recovery of resistance is triggered by PGE and PGI2, which may be elaborated by either COX-1 or COX-2.

Animals↗
PubMed2002

Bacterial translocation as a cause for septic complications in obstructive colonic ileus.

Failure of intestinal barrier function and subsequent translocation of microorganisms and their degradation products play a decisive role in development of systemic septic complications for many systemic and intra-abdominal pathologies, for example, following obstructive colonic ileus (OCI). This study was aimed at the evaluation of the intestinal barrier state in OCI. Sixty albino Wistar rats weighting 250 to 300 g (mean 265 g) were divided into four groups (15 animals in each). Acute colonic ileus (ACI) was modeled as follows except a control group (Group 1). Our objective was to examine changes in bacterial flora in the abdomen, mesenteric lymphatic nodes (MLN), liver, spleen, and lungs during the model of OCI after 72 hours following the beginning of experiment. The composition of parietal mucus in normal and in OCI 48 hours following the beginning of experiment examined. Interleukin (IL-VI) levels were determined in both portal and peripheral blood. The right-hand half of colon was ligated at the level of ileocaecal junction in animals of Group 2 (n = 15), whereas in animals of Group 3 (n = 15) it was ligated at the level of sigmoid colon. With the same purpose, a portion of the suspended caecal content was administered into lumen of the jejunum at a concentration of 10(6) colony-forming units (CFU) in animals of Group 4 (n = 15). Experimentally--induced OCI causes significant bacterial translocation (BT) in rats. The process of colonization of the proximal small intestine with colonic flora takes place under the conditions of ileus. The conditions favorable for the development of BT are generated with colonization of 10(6) CFU in volume. As a result, intestinal flora penetrates into the abdominal organs and lungs. Its highest concentrations are noted in the lymph nodes, lungs and liver. The modeling of the small intestine colonization with colonic flora (Group 4) demonstrates critical parameters of microbial semination.

Acute Disease↗
PubMed1997

Effect of terfenadine on TNF alpha release from peripheral blood mononuclear cells during cow's milk allergy.

BACKGROUND: In infants with cow's milk allergy and intestinal symptoms, peripheral blood mononuclear cells stimulated in vitro with cow's milk proteins, secrete large amounts of the proinflammatory cytokine TNF alpha thus altering intestinal barrier capacity. Terfenadine, an antihistaminic drug, inhibits the release of several inflammatory mediators, including histamine, prostaglandins and leukotrienes. OBJECTIVES: To test the potential ability of terfenadine to inhibit TNF alpha secretion by mononuclear cells from infants with cow's milk allergy. METHODS: Mononuclear cells from infants allergic to cow's milk proteins were stimulated in vitro for 6 days by a mixture of milk proteins (beta-lactoglobulin, alpha-lactalbumin and casein) with or without terfenadine (0.1-1 microM) and culture supernatants were assayed for TNF alpha by enzyme immunoassay. The effect of culture supernatants on intestinal barrier capacity was evaluated by measuring the electrical resistance (index of integrity) of filter-grown HT29-19 A intestinal cells in Ussing chambers. RESULTS: During active cow's milk allergy, mononuclear cells stimulated with cow's milk proteins secreted large amounts of TNF alpha which significantly reduced the electrical resistance of HT29-19 A intestinal cells. There was a dose-dependent decrease in TNF alpha secretion in the presence of terfenadine, with a maximal inhibition of 62% of this secretion at 1 microM. Accordingly, terfenadine-treated mononuclear cells supernatants did not alter the electrical resistance of intestinal HT29.19 A cells. CONCLUSION: These results indicate that in infants with intestinal dysfunction due to cow's milk allergy, terfenadine is a potent inhibitor of the TNF alpha secretion induced by sensitizing milk protein antigens. This inhibition prevents the degradation of intestinal function as measured in an intestinal cell line, in vitro.

Animals↗
PubMed2001

Probiotic bacteria enhance murine and human intestinal epithelial barrier function.

BACKGROUND & AIMS: The probiotic compound, VSL#3, is efficacious as maintenance therapy in pouchitis and ulcerative colitis. The aim of this study was to determine the efficacy of VSL#3 as a primary therapy in the treatment of colitis in the interleukin (IL)-10 gene-deficient mouse. Mechanisms of action of VSL#3 were investigated in T(84) monolayers. METHODS: IL-10 gene-deficient and control mice received 2.8 x 10(8) colony-forming units per day of VSL#3 for 4 weeks. Colons were removed and analyzed for cytokine production, epithelial barrier function, and inflammation. VSL#3 or conditioned media was applied directly to T(84) monolayers. RESULTS: Treatment of IL-10 gene-deficient mice with VSL#3 resulted in normalization of colonic physiologic function and barrier integrity in conjunction with a reduction in mucosal secretion of tumor necrosis factor alpha and interferon gamma and an improvement in histologic disease. In vitro studies showed that epithelial barrier function and resistance to Salmonella invasion could be enhanced by exposure to a proteinaceous soluble factor secreted by the bacteria found in the VSL#3 compound. CONCLUSIONS: Oral administration of VSL#3 was effective as primary therapy in IL-10 gene-deficient mice, and had a direct effect on epithelial barrier function.

Animals↗
PubMed2004

Effect of probiotics on gastrointestinal symptoms and small intestinal permeability in children with atopic dermatitis.

OBJECTIVE: To determine whether probiotic lactobacilli may alleviate small intestinal inflammation and strengthen the intestinal barrier function in children with atopic dermatitis. STUDY DESIGN: In a double-blinded, placebo-controlled, cross-over study, probiotic lactobacilli (Lactobacillus rhamnosus 19070-2 and L reuteri DSM 12246) were administered for 6 weeks to 41 children with moderate and severe atopic dermatitis. Gastrointestinal symptoms were registered before and during treatment and small intestinal permeability was measured by the lactulose-mannitol test. RESULTS: During Lactobacillus supplementation, there was a significant decrease in the frequency of gastrointestinal symptoms (39% during the placebo period versus 10% during active treatment, P=.002). There was a positive association between the lactulose to mannitol ratio and the severity of the eczema (r=0.61, P=.02 after placebo and r=0.53, P=.05 after active treatment). After probiotic treatment, the lactulose to mannitol ratio was lower (0.073) than after placebo (0.110, P=.001). CONCLUSIONS: Impairment of the intestinal mucosal barrier appears to be involved in the pathogenesis of atopic dermatitis. The study suggests that probiotic supplementation may stabilize the intestinal barrier function and decrease gastrointestinal symptoms in children with atopic dermatitis.

Adolescent↗
PubMed2006

Antibody-mediated antigen sampling across intestinal epithelial barriers.

The epithelium of the gastrointestinal tract is the interface between luminal contents and the mucosal immune system. It must function as a selective barrier to limit penetration of antigens yet keep the mucosal immune system "informed" for the purpose of generating oral tolerance responses to food antigens or commensal organisms and host defense responses against pathogens. Alterations in epithelial barrier function have been proposed to play a significant role in gastrointestinal disease. In this review, we will discuss mechanisms of regulation of epithelial barrier function, and we will focus on the emerging understanding of how secreted immunoglobulins play a role in antigen-specific antigen sampling across the gastrointestinal epithelium.

Antibodies↗
PubMedDate not supplied

Glutamine stabilizes intestinal permeability and reduces pancreatic infection in acute experimental pancreatitis.

Intestinal barrier failure and subsequent translocation of bacteria from the gut play a decisive role in the development of systemic infections in severe acute pancreatitis. Glutamine (GLN) has been shown to stabilize gut barrier function and to reduce bacterial translocation in various experimental settings. The aim of this study was to evaluate whether GLN reduces gut permeability and bacterial infection in a model of acute necrotizing pancreatitis. Acute necrotizing pancreatitis was induced in 50 rats under sterile conditions by intraductal infusion of glycodeoxycholic acid and intravenous infusion of cerulein. Six hours after the induction of pancreatitis, animals were randomly assigned to one of two groups: standard total parental nutrition (TPN) or TPN combined with GLN (0.5 g/kg(-1)/day(-1)). After 96 hours, the animals were killed. The pancreas was prepared for bacteriologic examination, and the ascending colon was mounted in a Ussing chamber for determination of transmucosal resistance and mannitol flux as indicators of intestinal permeability. Transmucosal resistance was 31% higher in the animals treated with GLN- supplemented TPN compared to the animals given standard TPN. Mannitol flux through the epithelium was decreased by 40%. The prevalence of pancreatic infections was 33% in animals given GLN-enriched TPN as compared to 86% in animals receiving standard TPN (P < 0.05). Adding GLN to standard TPN not only reduces the permeability of the colon but decreases pancreatic infections in acute necrotizing pancreatitis in the rat. This confirms previous reports that GLN decreases bacterial translocation by stabilizing the intestinal mucosal barrier. The present findings provide the first evidence suggesting that stabilizing the intestinal barrier can reduce the prevalence of pancreatic infection in acute pancreatitis and that GLN may be useful in preventing septic complications in clinical pancreatitis.

Acute Disease↗
PubMed2002

Microscopy of bacterial translocation during small bowel obstruction and ischemia in vivo--a new animal model.

BACKGROUND: Existing animal models provide only indirect information about the pathogenesis of infections caused by indigenous gastrointestinal microflora and the kinetics of bacterial translocation. The aim of this study was to develop a novel animal model to assess bacterial translocation and intestinal barrier function in vivo. METHODS: In anaesthetized male Wistar rats, 0.5 ml of a suspension of green fluorescent protein-transfected E. coli was administered by intraluminal injection in a model of small bowel obstruction. Animals were randomly subjected to non-ischemic or ischemic bowel obstruction. Ischemia was induced by selective clamping of the terminal mesenteric vessels feeding the obstructed bowel loop. Time intervals necessary for translocation of E. coli into the submucosal stroma and the muscularis propria was assessed using intravital microscopy. RESULTS: Bacterial translocation into the submucosa and muscularis propria took a mean of 36 +/- 8 min and 80 +/- 10 min, respectively, in small bowel obstruction. Intestinal ischemia significantly accelerated bacterial translocation into the submucosa (11 +/- 5 min, p < 0.0001) and muscularis (66 +/- 7 min; p = 0.004). Green fluorescent protein-transfected E. coli were visible in frozen sections of small bowel, mesentery, liver and spleen taken two hours after E. coli administration. CONCLUSIONS: Intravital microscopy of fluorescent bacteria is a novel approach to study bacterial translocation in vivo. We have applied this technique to define minimal bacterial transit time as a functional parameter of intestinal barrier function.

Animals↗
PubMed2005

Polyamines regulate expression of E-cadherin and play an important role in control of intestinal epithelial barrier function.

Epithelial cells line the gastrointestinal mucosa and form an important barrier that protects the subepithelial tissue against a wide array of noxious substances, allergens, viruses and luminal microbial pathogens. Restoration of mucosal integrity following injury and various environmental stresses requires epithelial cell decisions that regulate signaling networks controlling gene expression, survival, migration and proliferation. Recently, it has been shown that polyamines play an important role in the regulation of cell-cell interactions and are critical for maintenance of intestinal epithelial integrity. Both the function of polyamines in expression of adherens junction proteins and their possible mechanisms, especially in implication of intracellular Ca2+ and c-Myc transcription factor, are the subject of this review article.

Animals↗
PubMed2000

A role for Salmonella fimbriae in intraperitoneal infections.

Enteric bacteria possess multiple fimbriae, many of which play critical roles in attachment to epithelial cell surfaces. SEF14 fimbriae are only found in Salmonella enterica serovar Enteritidis (S. enteritidis) and closely related serovars, suggesting that SEF14 fimbriae may affect serovar-specific virulence traits. Despite evidence that SEF14 fimbriae are expressed by S. enteritidis in vivo, previous studies showed that SEF14 fimbriae do not mediate adhesion to the intestinal epithelium. Therefore, we tested whether SEF14 fimbriae are required for virulence at a stage in infection after the bacteria have passed the intestinal barrier. Polar mutations that disrupt the entire sef operon decreased virulence in mice more than 1,000-fold. Nonpolar mutations that disrupted sefA (encoding the major structural subunit) did not affect virulence, but mutations that disrupted sefD (encoding the putative adhesion subunit) resulted in a severe virulence defect. The results indicate that the putative SEF14 adhesion subunit is specifically required for a stage of the infection subsequent to transit across the intestinal barrier. Therefore, we tested whether SefD is required for uptake or survival in macrophages. The majority of wild-type bacteria were detected inside macrophages soon after i.p. infection, but the sefD mutants were not readily internalized by peritoneal macrophages. These results indicate that the potential SEF14 adhesion subunit is essential for efficient uptake or survival of S. enteritidis in macrophages. This report describes a role of fimbriae in intracellular infection, and indicates that fimbriae may be required for systemic infections at stages beyond the initial colonization of host epithelial surfaces.

Animals↗