Roberto Gennari

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.

Granulocyte macrophage colony-stimulating factor improves survival in two models of gut-derived sepsis by improving gut barrier function and modulating bacterial clearance.

ObjectiveThe effect of recombinant murine granulocyte macrophage colony-stimulating factor (rmGM-CSF) on survival and host defense was studied using two clinically relevant models of infection that included transfusion-induced immunosuppression. Summary Background DataGranulocyte macrophage colony-stimulating factor improves resistance in several models of infection, but its role in transfusion-induced immunosuppression and bacterial translocation (gut-derived sepsis) has not been defined. MethodsBalb/c mice were treated with 100 ng of rmGM-CSF or placebo for 6 days in a model of transfusion, burn, and gavage, or cecal ligation and puncture (CLP). Translocation was studied in the first model. ResultsSurvival after transfusion, burn, and gavage was 90% in rmGM-CSF-treated animals versus 35% in the control group (p < 0.001). After CLP, survival was 75% in the rmGM-CSF group versus 30% in the control group (p = 0.01). Less translocation and better killing of bacteria was observed in the tissues in animals treated with rmGM-CSF. ConclusionThe ability of rmGM-CSF to improve gut barrier function and enhance killing of translocated organisms after burn injury-induced gut origin sepsis was associated with improved outcome. Granulocyte macrophage colony-stimulating factor also improved survival after CLP.

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.

Effects of the angiotensin converting enzyme inhibitor enalapril on bacterial translocation after thermal injury and bacterial challenge.

ABSTRACT Burn injury and sepsis produce acute gastrointestinal derangements that may predispose patients to bacterial translocation. We studied the effects of enalapril, an angiotensin converting enzyme inhibitor (ACEi), on gastrointestinal anatomic alterations, bacterial translocation, and related mortality during gut-derived sepsis in burned mice that had received a prior bacterial challenge. BALB/c mice (n = 111) were treated with enalapril 10 or 1 mg/Kg body weight or sterile saline as control twice daily for 3 days. They were then gavaged with 109 111ln 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). Survival was significantly higher in the group receiving enalapril 10 mg/Kg compared with control (75% vs. 10%). Mice treated with enalapril maintained small intestine weight, measured 4 h postburn, and ileal mucosal height was preserved, whereas burned untreated animals lost intestinal weight and mucosal height. Bacterial translocation was decreased in mice treated with enalapril, but killing was unaffected. This study suggests that treatment with enalapril positively affects the outcome in gut-derived sepsis by ameliorating gastrointestinal structural and functional damage and decreasing bacterial translocation.

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%, ρ = .004, and 60 vs. 20%, ρ = .02, respectively). A lower amount of translocation was observed in the spleen (ρ ≤ .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.

Effect of dietary ribonucleic acid on bacterial translocation and 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.

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.