Salmonella flagellin-dependent proinflammatory responses are localized to the conserved amino and carboxyl regions of the protein.

Flagellin, the monomeric subunit of flagella, is an inducer of proinflammatory mediators. Bacterial flagellin genes have conserved domains (D1 and D2) at the N terminus and C terminus and a middle hypervariable domain (D3). To identify which domains induced proinflammatory activity, r6-histidine (6HIS)-tagged fusion constructs were generated from the Salmonella dublin (SD) fliC flagellin gene. A full-length r6HIS SD flagellin (6HIS flag) induced IkappaBalpha loss poststimulation and NF-kappaB activation in Caco-2BBe cells and was as potent as native-purified SD flagellin. IFN-gamma-primed DLD-1 cells stimulated with 1 microg/ml of 6HIS flag induced high levels of NO (60 +/- 0.95 microM) comparable to the combination of IL-1beta and IFN-gamma (77 +/- 1.2) or purified native SD flag (66.3 +/- 0.98). Selected rSD flagellin proteins representing the D1, D2, or D3 domains alone or in combination were tested for proinflammatory properties. Fusion proteins representing the D3, amino, or carboxyl regions alone did not induce proinflammatory mediators. The results with a recombinant protein containing the amino D1 and D2 and carboxyl D1 and D2 separated by an Escherichia coli hinge (ND1-2/ECH/CD2) indicated that D1 and D2 were bioactive when coupled to an ECH element to allow protein folding. This chimera, but not the hinge alone, induced IkappaBalpha degradation, NF-kappaB activation, and NO and IL-8 production in two intestinal epithelial cell lines. ND1-2/ECH/CD2-1 also induced high levels of TNF-alpha (900 pg/ml) in human monocytes comparable to native SD flagellin (991.5 pg/ml) and 6HIS flag (987 pg/ml). The potent proinflammatory activity of flagellin, therefore, resides in the highly conserved N and C D1 and D2 regions.

Comparison of translocation of different types of microorganisms from the intestinal tract of burned mice.

The aim of this study was to compare the ability of various microorganisms to translocate from the intestine to the mesenteric lymph nodes (MLNs), liver, and spleen in a burned mouse model. Balb/c mice were gavaged with 1 x 10(9) or 1 x 10(10) of one of 11 different microorganisms. All animals were then given a 20% burn. Survival after 10 days showed no significant difference between any of the groups at the 10(10) dose. At the 10(9) dose, significantly higher survival rates were found in three of the 11 strains. Microbial translocation (gavage of 10(10) 111In-labeled organisms) and host's ability to kill translocated bacteria (viable bacteria in tissues) were measured followed by burn injury and sacrifice four hours later. Translocation and killing of Staphylococcus epidermidis and Escherichia coli was high in the MLNs compared with all other groups but translocation was lower to the liver. Klebsiella, Pseudomonas, and Serratia translocated more evenly to all the tissues. However, these groups showed very high clearance of bacteria in the liver and spleen except for Klebsiella and one strain of Pseudomonas in the spleen. Candida showed poor translocation to all of the tissues and high clearance. It is concluded that various strains of bacteria translocate from the intestine to a similar degree after injury, but the tissues to which they translocate and the rate at which they are killed are somewhat strain dependent.

Flagellin, a novel mediator of Salmonella-induced epithelial activation and systemic inflammation: I kappa B alpha degradation, induction of nitric oxide synthase, induction of proinflammatory mediators, and cardiovascular dysfunction.

Gram-negative sepsis is mediated by the actions of proinflammatory genes induced in response to microbes and their products. We report that flagellin, the monomeric subunit of flagella, is a potent proinflammatory species released by Salmonella. Flagellin (1 microgram/ml) induces IkappaBalpha degradation, NF-kappaB nuclear translocation, and inducible NO synthase expression in cultured intestinal epithelial cells (IEC). Aflagellic Salmonella mutants do not induce NF-kappaB activation or NO production by cultured IEC. Antiserum to flagellin blocks NO production in IEC induced by medium conditioned by a variety of motile Gram-negative enteric pathogens (Escherichia coli, Salmonella muenchen, Serratia marcescens, Proteus mirabilis, and Proteus vulgaris). Flagellin, when injected systemically (approximately 10 microgram/mouse), induces systemic inflammation characterized by the systemic expression of a range of proinflammatory cytokines and chemokines and of inducible NO synthase. At higher doses (approximately 300 microgram/mouse), flagellin induces shock, characterized by hypotension, reduced vascular contractility in mice, and death. The effects of flagellin do not diminish in C3H/HeJ LPS-resistant mice, indicating that the Toll-like receptor-4 receptor is not involved in flagellin's actions. In LPS-resistant mice, i.p. injection of S. dublin flagellin or medium conditioned by wild-type S. dublin induces serum IFN-gamma and TNF-alpha, whereas medium conditioned by aflagellic mutants has no effect. Flagellin can be detected in the blood of rats with septic shock induced by live bacteria at approximately 1 microg/ml. We propose that flagellin released by Gram-negative pathogens may contribute to the inflammatory response by an LPS- and Toll-like receptor-4-independent pathway.

Heat shock inhibits phosphorylation of I-kappaBalpha.

Previous studies demonstrated that induction of the heat shock response is associated with inhibition of the proinflammatory transcription factor NF-kappaB by a mechanism involving inhibition of I-kappaBalpha degradation. To provide further insight regarding the interactions of these fundamental cellular responses, the present experiments were designed to elucidate the mechanism(s) by which heat shock inhibits degradation of I-kappaBalpha. In an in vitro model of inflammatory cell signaling, treatment of RAW 264.7 murine macrophages with LPS (100 ng/mL) caused rapid degradation of I-kappaBalpha. Heat shock, 1 h before treatment with LPS, completely inhibited LPS-mediated degradation of I-kappaBalpha. Immunoprecipitation studies demonstrated that heat shock inhibited LPS-mediated ubiquitination of I-kappaBalpha. Western-blot analyses using a phosphorylated I-kappaBalpha-specific antibody demonstrated that heat shock inhibited LPS-mediated phosphorylation of I-kappaBalpha. In contrast, heat shock induced phosphorylation of c-jun. In murine fibroblasts having genetic ablation of the heat shock factor-1 gene, heat shock inhibited tumor necrosis factor-alpha mediated degradation of I-kappaBalpha. We conclude that the mechanism by which heat shock inhibits LPS-mediated degradation of I-kappaBalpha involves specific inhibition of I-kappaBalpha phosphorylation and subsequent I-kappaBalpha ubiquitination. In addition, this mechanism does not involve activation of heat shock factor-1 or the heat shock proteins regulated by heat shock factor-1.

Sodium arsenite induces the stress response in the gut and decreases bacterial translocation in a burned mouse model with gut-derived sepsis.

Bacteria translocation from the bowel to systemic organs after burn injury may contribute to or be a cause of sepsis and multiple organ failure. The stress response confers protection under stressful conditions that would otherwise lead to cell damage or death. We investigated whether prior induction of the stress response by sodium arsenite could affect bacterial translocation after thermal injury. HSP-70, a highly stress-inducible protein, was used as a marker for induction of the stress response. Balb/c mice were intravenously injected with 4 mg/kg of sodium arsenite and killed at selected times post-treatment. Other treated mice were then gavaged with 10(10) E. coil or 10(10) 111In-labeled E. coil followed by a 20% burn. Survival was observed for 10 days. Mice gavaged with radiolabeled E. coil were killed 4 h post-burn to determine the effect of HSP-70 induction on microbial translocation in mesenteric lymph nodes (MLN), liver, and spleen. Sodium arsenite-injected mice showed HSP-70 induction in the ileum that increased in a time-dependent manner with peak expression 12 h post-injection. Treated mice showed a significantly higher survival rate (93%) than controls (46%; P < 0.05), and detection of 111In-labeled E. coli was significantly less in the liver and spleen (P < 0.05). These data show that sodium arsenite induced HSP-70 expression in the small intestine. The stress response was associated with significantly increased survival and significant decrease in detection of 111In-labeled E. coil in the liver and spleen in a burned mouse model with gut-derived sepsis.

Bacterial invasion is not required for activation of NF-kappaB in enterocytes.

Pathogenic enteric microorganisms induce the NF-kappaB-dependent expression of proinflammatory genes in intestinal epithelial cells. The purpose of the present study was to clarify the contribution of microbial invasion to the degradation of the regulatory protein Ikappa Balpha and the subsequent activation of NF-kappaB in cultured intestinal epithelial cells. Caco-2BBe cells were incubated with Salmonella dublin, Salmonella typhimurium, or a weakly invasive strain of E. coli. S. dublin and S. typhimurium (10(7) organisms/ml) induced equivalent concentration-dependent gel mobility shifts of an NF-kappaB consensus sequence that was preceded by Ikappa Balpha degradation. E. coli (10(7) organisms/ml) did not induce Ikappa Balpha degradation or NF-kappaB translocation. Pretreatment with cytochalasin D blocked invasion of all three strains but had no effect on Ikappa Balpha degradation or NF-kappaB activation. S. dublin and S. typhimurium adhered to Caco-2BBe cells 3- to 10-fold more than E. coli. NF-kappaB activation was prevented by physical separation of S. dublin from Caco-2BBe cells by a 0. 4-micrometers-pore-size filter. Our results imply that bacterial adhesion, rather than invasion or release of a secreted factor, is sufficient to induce IkappaBalpha degradation and NF-kappaB activation in intestinal epithelial cells. Our data suggest that strategies to reduce enteric inflammation should be directed to the reduction of bacterial enterocyte adhesion.

Rapid and prolonged impairment of gut barrier function after thermal injury in mice.

Loss of gut barrier function after burn injury can be important in the pathogenesis of systemic infections and organ dysfunction. The purpose of this study was to determine how rapidly impairment of gut barrier function occurs after burn injury and how long it persists. BALB/c mice were gavaged with 10(10) (111)In-oxine-labeled Escherichia coli 3 h before inflicting a 20% total body surface area burn. They were then killed at 5, 15, 30, 60, 120, or 240 min post-burn. Additional mice were given a 20% or 30% burn injury and were randomized into eight groups, which were killed at either 4 h or 1, 2, 4, 7, 14, or 21 days post-burn. Each mouse was gavaged with 10(10) (111)In-oxine-labeled E. coli 4 h before sacrifice to determine the magnitude of translocation. Gut barrier function was impaired as early as 5 min post-burn and was maximal by 4 h. Rapid improvement was observed by 24 h, followed by slow improvement, but with persistent abnormality through 21 days post-burn. Killing of translocated bacteria was impaired at 4 h and day 7 post-burn, according to the percentage of viable E. coli that remained alive in the tissues. The magnitude of gut dysfunction following burn injury is temporally related.

Bacterial induction of inducible nitric oxide synthase in cultured human intestinal epithelial cells.

BACKGROUND & AIMS: Enterocytes play a major role in the mucosa as a source of proinflammatory cytokines and cytotoxins. We tested the hypothesis that bacteria induce expression of the inducible nitric oxide synthase (iNOS) in cultured human enterocytes. METHODS: DLD-1 and Caco-2BBe cell monolayers exposed to Salmonella dublin were analyzed for iNOS up-regulation and nitric oxide production (NOx) in the presence of various proinflammatory cytokines. RESULTS: S. dublin augmented NOx in interferon gamma (IFN-gamma)-primed cells but had no independent effect on iNOS expression. S. dublin-induced NOx was not mediated by endotoxin and was augmented by an enteroinvasive phenotype. In DLD-1 cells, S. dublin-mediated NOx was blocked by inhibitors of nuclear factor kappa B (NF-kappa B) and tyrosine kinase activation and was steroid resistant. Cis-acting elements in the human iNOS promoter responsive to endotoxin and S. dublin stimulation of IFN-gamma-treated DLD-1 cells were identified between 10.9 and 8.7 kilobases upstream of the transcription initiation site. CONCLUSIONS: S. dublin alters the regulation of iNOS messenger RNA in IFN-gamma-treated intestinal epithelial cells via a steroid-resistant pathway involving NF-kappa B and tyrosine kinase activity. Because bacterial interaction with cytokine-primed epithelial cells induces the synthesis of NO, an endogenous antimicrobial agent, these findings may have implications for the regulation of mucosal immunity.

The effect of blood transfusion on susceptibility to bacterial infection in genetically defined mouse models.

BACKGROUND: Blood transfusions suppress immune function and increase susceptibility to infection, but the effects are not consistent. STUDY DESIGN AND METHODS: Genetically defined mouse strains with the same or different haplotypes were used as blood transfusion recipients and donors. Transfused animals were subjected to cecal ligation and puncture (CLP) and followed for survival or were injected intravenously with Candida albicans to follow clearance of the Candida from the kidneys. RESULTS: BALB/c (H-2d) mice transfused with C3H/HeJ (H-2k) or DBA/2 (H-2d) blood followed by CLP showed significantly lower survival (7 and 10%) than mice transfused with syngeneic blood (61%) or saline controls (56%). Lower survival was also observed in C3H/HeJ (H-2k) mice transfused with BALB/c (H-2d) blood and subjected to CLP (25%) compared with syngeneic transfusion (80%) or saline controls (70%). C57BL/6J (H-2b) mice showed minimal increases in mortality after CLP after transfusion with blood from C3H/HeJ (H-2k) (60% survival), DBA/2 (H-2d) (70% survival), or BALB/c (H-2d) mice (90% survival). When C. albicans was infused intravenously into transfused mice, a similar pattern of altered resistance to infection was found. CONCLUSION: The ability of blood transfusions to increase susceptibility to bacterial infection appears to be dependent on genetic factors unrelated to the major haplotype.

Effect of dietary ribonucleic acid on bacterial translocationand survival following blood transfusion and thermal injury.

Ribonucleic acid (RNA) has been shown to have a key role in the maintenance of normal cellular function and host resistance to infection. The effect of experimental diets containing RNA on microbial translocation, killing of translocated bacteria and the survival rate of the host was studied in a burn animal model which included immunosuppression. Balb/c mice were fed for 10 days with an RNA supplemented diet (AIN/76A). Control groups were fed with two commercial diets: AIN-76A or Purina chow 5001 (chow). After 10 days of feeding, all animals received an allogenic transfusion. On day 15 the animals were gavaged with 10(10)(14)C radiolabeled or unlabeled Escherichia coli, and given a 20% total body surface area (TBSA) burn injury. Animals gavaged with unlabeled bacteria were observed for survival (n = 60) and animals gavaged with labeled bacteria were sacrificed 4 h post-burn (n = 30) and the mesenteric lymph nodes, liver and spleen were harvested. Slightly less translocation was observed in the liver and spleen of animals fed on RNA diet. Bacterial counts were measured and the percentages of translocated organisms that survived in the tissues were calculated and showed no statistical differences between the three groups. Survival was 45% in RNA group versus 55% in the non-supplemented AIN-76A and 50% in the chow group. It is concluded that a diet enriched in RNA slightly affects bacterial translocation but does not affect survival after severe injury.

Dietary fatty acids modulate host bacteriocidal response,microbial translocation and survival following blood transfusion and thermal injury.

The effect of dietary lipids on bacterial translocation, killing of translocated organisms and host survival was studied in a burned animal model. Balb/c mice were fed with one of the three experimental AIN-76A diets (containing 15% of energy from fish oil, safflower oil or a 50:50 mixture), AIN-76A without added lipids or a nonpurified stock diet. All animals were transfused on day 10. On day 15, the animals were gavaged with 10(10) 14C radiolabelled Escherichia coli and given a 20% burn injury. Survival was 84% in the fish oil group versus 36% in the safflower oil and 50:50 diet groups, and 25% and 20% in the two control groups (P < 0.0001). The numbers of viable translocating bacteria were reduced in all tested organs in the fish oil groups compared to the other groups. It is concluded that a diet enriched in fish oil has beneficial effects during gut-derived sepsis.

Granulocyte colony-stimulating factor enhances killing of translocated bacteria but does not affect barrier function in a burn mouse model.

BACKGROUND: Granulocyte colony-stimulating factor drives the proliferation and differentiation of granulocytes and also enhances their bactericidal and phagocytic activity. The present study was undertaken to investigate the effects of murine granulocyte colony-stimulating factor (mG-CSF) on bacterial translocation and gut-derived sepsis after burn injury. METHODS: In experiment I, BALB/c mice were randomized into two treatment groups, which received 1 microgram/mouse of mG-CSF subcutaneously for either 1 (n = 16) or 2 days (n = 15). Controls received saline (n = 16). After treatment, all animals were gavaged with 10(10) 111In Escherichia coli and then given a 20% burn. All groups were observed 10 days for survival. In experiment II, three additional groups (n = 6/group) received the same treatment as above but were killed 4 hours after burn injury. Mesenteric lymph nodes, liver, and spleen were harvested to measure radionuclide counts (disintegrations per minute per gram of tissue) and colony-forming units (CFU/g of tissue) and to calculate the percentage of viable bacteria (% alive). RESULTS: Experiment I: 10-day survival was significantly higher in groups treated with mG-CSF for 1 or 2 days (75% and 73%, respectively), compared with controls (43.7%), p = 0.001. Experiment II: no differences in translocation to the tissues were observed among any of the groups, according to radionuclide counts. However, quantitative colony counts and calculated percentage of viable bacteria showed that killing was enhanced in the mesenteric lymph nodes and liver of animals that received mG-CSF, but this was significant only in the liver for both treatment times (1 day, p = 0.021 and 2 day, p = 0.009). CONCLUSION: These data suggest that treatment with mG-CSF does not improve gut barrier function, but does enhance the host's ability to kill translocated organisms and improve survival in a gut-derived sepsis model.

Steroid therapy can modulate gut barrier function, host defense, and survival in thermally injured mice.

Prednisone may be immunosuppressive and dehydroepiandrosterone may stimulate the immune response, but their effect on gut-origin sepsis caused by bacterial translocation has not been studied. Balb/c mice were treated orally with prednisone (1 or 10 mg/kg/day) or saline for 4 days before receiving gavage with 10 (10) 14 C-labeled Escherichia coli and a 20% thermal injury. Mice were transfused with allogeneic blood and given dehydroepiandrosterone (5 or 25 mg/kg/day) or vehicle subcutaneously for 4 days before bacterial gavage and thermal injury. Some groups in each experiment were observed 10 days for mortality and others were sacrificed 4 hr postburn to measure translocation and survival of translocated bacteria. Survival in prednisone treated animals was 25% (10 mg/kg/day) and 75% (1 mg/kg/day) versus 80% for controls. Following dehydroepiandrosterone administration, survival was 72% (25 mg/kg/day/group) and 30% (5 mg/kg/day/group) versus 16% for controls. High dose prednisone increased bacterial translocation to the intestinal wall and mesenteric lymph nodes and greatly impaired killing of translocated E. coli. In contrast, dehydroepiandrosterone (25 mg/kg) did not affect translocation but significantly improved bacterial killing. Prednisone and dehydroepiandrosterone exert opposite effects during gut-derived sepsis.

High protein diets are associated with increased bacterial translocation in septic guinea pigs.

During sepsis, body protein stores are decreased due to an increase in protein catabolism. The utilization of nutritional support with high-protein diets has been used as a solution to the problem of sepsis-induced protein loss. Work from our laboratory, however, has shown that diets low in protein (5% of total calories) improve survival in septic animals as compared to high protein (20%) diets. The present study investigated the relationship between low-protein diets and improved survival by determining whether septic animals receiving high-protein diets have increased bacterial translocation. Sepsis was induced in guinea pigs by the implantation of an osmotic minipump into the peritoneal cavity containing an equal mixture of Escherichia coli (10(8)) and Staphylococcus aureus (10(8)) or saline. On Day 3 postlaparotomy, the animals were randomized to one of four groups. The groups consisted of septic and nonseptic animals that received a diet with 5 or 20% of total calories as protein. Following 4 days of diet all animals received an instillation of 14C labeled E. coli (10(10)). Four hours later the animals were sacrificed and blood, mesenteric lymph nodes, spleen, lungs, and liver were removed for determination of radionuclide counts. Results indicated that the septic animals that received the high protein diet had more bacterial translocation, as indexed by higher radionuclide counts in the MLN, liver, lung and blood. These findings suggest that a low protein, enterally fed diet may improve survival in septic patients by decreasing the incidence of bacterial translocation.

Effect of different combinations of dietary additives on bacterial translocation and survival in gut-derived sepsis.

BACKGROUND: Dietary arginine, glutamine, and fish oil each have been shown to improve resistance to infection. The purpose of this study was to assess the potential benefit of different combinations and amounts of these components on bacterial translocation and related mortality during gut-derived sepsis. METHODS: Balb/c mice were fed for 10 days with an AIN-76A diet supplemented with different combinations and percentages of arginine, glutamine, glycine, fish oil, and medium-chain triglycerides. Controls were fed a complete AIN-76A diet or chow. After 10 days of feeding, all animals were transfused. On day 15, the animals were gavaged with 10(10) 111In-radiolabeled or unlabeled Escherichia coli and given a 30% burn injury. Animals gavaged with unlabeled bacteria were observed for survival (n = 317). Groups that showed the best survival as well as control groups were gavaged with labeled bacteria and killed 4 hours postburn (n = 60) for harvest of mesenteric lymph nodes, liver and spleen. RESULTS: Mice fed diets enriched with 5% fish oil + 2% arginine, 2% arginine + 2% glutamine, or 5% fish oil + 2% glutamine had higher survival than control groups. The animals fed fish oil+glutamine had significantly reduced translocation to the liver and spleen. Animals fed arginine+glutamine had an enhanced ability to kill translocated organisms in the liver compared with other groups. Fish oil+arginine improved both barrier function and microbial killing. CONCLUSIONS: Feeding with arginine+glutamine, fish oil+arginine, or fish oil+glutamine supplemented diets positively affects the outcome in a gut-derived sepsis model.

Bacterial translocation-related mortality may be associated with neutrophil-mediated organ damage.

Balb/c mice were transfused with .2 mL of C3H/HeJ mouse blood. 5 days later, the mice were gavaged with 10(10) 14C-labeled Escherichia coli, and a 20% full thickness flame burn was inflicted. Additional animals were treated with enisoprost (prostaglandin E1 (PGE1) analog) 200 micrograms/kg/day orally for 3 days before burn. Bacterial translocation was determined by both radionuclide counts (dpm) and viable colony counts 24 h post burn. Neutrophil accumulation was evaluated by the measurement of myeloperoxidase (MPO) in the liver. In addition, splenic macrophages were separated and cultured for 24 h with or without 10 micrograms/mL of LPS. Tumor necrosis factor, interleukin-1 (IL-1), IL-6, and PGE2 were measured in the cell culture supernatants. Consistent with previous work, enisoprost significantly reduced translocation. MPO in the liver was significantly greater in the control group compared to the enisoprost group. There was a significant correlation between MPO content and the degree of bacterial translocation (p < .05). Lipopolysaccharide-stimulated macrophage production of IL-1, IL-6, and PGE2 were significantly greater in the enisoprost group.

Translocation and survival of Bacteroides fragilis after thermal injury.

B. fragilis and E. coli were labeled with tritiated (3H) thymidine, and 10(10) of each were given separately by gavage in Balb/c mice immediately before a 20% burn injury was inflicted. Control groups received gavage with 3H-B. fragilis or 3H-E. coli without burn. Four hours after burn or gavage was administered, the animals were killed, and the radionuclide and colony counts were determined in the mesenteric lymph nodes, liver, and spleen. Additional groups of mice receiving gavage (B. fragilis or E. coli) and burn were observed for 10 days to study survival. The results showed that 3H-B. fragilis translocated to a greater extent than 3H-E. coli but that fewer B. fragilis than E. coli survived in tissues. Survival was 86% for animals challenged with B. fragilis versus 53% for animals challenged with E. coli. It is concluded that in this model B. fragilis translocates extensively after burn injury and that survival is closely related to the destruction of translocated bacteria.

Oral glutamine decreases bacterial translocation and improves survival in experimental gut-origin sepsis.

BACKGROUND: Glutamine has been shown to be an important dietary component for the maintenance of gut metabolism. The purpose of this study was to assess the potential benefit of glutamine-enriched diets on experimental gut-derived sepsis. METHODS: BALB/c mice were fed either 2% glutamine-supplemented or 1% glycine-supplemented (near-isonitrogenous control) AIN-76A diets. Control mice received either nonsupplemented AIN-76A or regular Purina Rodent Laboratory Mouse Chow 5001 diets. After 10 days of feeding, the mice were transfused with allogeneic blood (from C3H/HeJ mice), and the feeding protocols were continued for an additional 5 days. The mice then underwent gavage with 10(10) Escherichia coli labeled with either indium-111 oxine or [14C]glucose followed immediately by a 20% burn injury. Some mice were observed 10 days postburn for survival rates. Others were killed 4 hours after burn, and the mesenteric lymph nodes, liver, and spleen were harvested to determine radionuclide and bacterial colony counts. The percentages of viable translocated E coli were also calculated. RESULTS: Mice fed glutamine-enriched diets had a lower degree of translocation (as measured by both radionuclide and bacterial counts) to the tissues than did the other groups and had an improvement in the ability to kill translocated E coli (as measured by the percentage of viable bacteria). Survival was significantly higher in the group fed 2% glutamine (81%) compared with the groups fed 1% glycine (36%), AIN-76A (35%), and Purina Rodent Laboratory Mouse Chow 5001 (36%) diets (p < .004). CONCLUSIONS: Glutamine-supplemented enteral diets may exert important benefits in preventing gut-origin sepsis after trauma.

Effects of antimurine interleukin-6 on bacterial translocation during gut-derived sepsis.

BACKGROUND: Recent studies have shown that interleukin-6 (IL-6) is involved in the systemic changes that are associated with infection and tissue injury and that there is a correlation between high levels of IL-6 and poor outcome during several pathologic conditions. OBJECTIVE: The effects of antimurine IL-6 antibody on survival and host defense were studied in a clinically relevant model of infection. METHODS: Balb/c mice were treated with 10 micrograms of antimurine interleukin-6, a nonspecific mouse IgG, or placebo 1 hour before they underwent bacterial challenge by gavage of 10(10) Escherichia coli and burn injury. Survival and the extent of translocation of E coli were determined as well as the correlation between the IL-6 levels and survival times. RESULTS: Survival after burn and gavage was 90% in animals treated with antimurine interleukin-6 vs 50% in animals treated with nonspecific IgG and 30% in saline-treated controls. A significant correlation between the levels of IL-6 and survival time was observed. Less translocation and better killing of bacteria were observed in the tissues of animals treated with antimurine interleukin-6. CONCLUSIONS: Interleukin-6 appears to play a major role in both the intensity of translocation of E coli from the intestine following burn injury and the host's ability to kill translocated organisms. Improved outcome was associated with a reduction of IL-6 levels by anti-IL-6 antibody.

Heparan sulfate increases survival during gut-derived sepsis by decreasing bacterial translocation and enhancing host defense.

The effect of heparan sulfate (HS) on survival rate, bacterial translocation, and host defense was studied in a model of gut-derived sepsis that included transfusion-induced immunosuppression. Balb/c mice were treated pre- and postburn injury and bacterial challenge with HS, 5 mg/kg/day, or sterile phosphate-buffered saline. The HS pre- and postburn treated animals showed a significant improvement in survival compared to control animals (80 vs. 30%, p = .004, and 60 vs. 20%, p = .02, respectively). A lower amount of translocation was observed in the spleen (p < or = .001) of the HS group compared to control group. Quantitative colony counts and the calculated percentage of viable bacteria showed that the ability to kill translocated organisms was enhanced in all tissues of the animals receiving HS. These data suggest that treatment with HS positively affects the outcome in gut-derived sepsis. The beneficial effect was related both to an improved gut barrier function and to an enhanced host defense.