The gut as a source of inflammatory cytokines after stimulation with endotoxin

OBJECTIVE

To find out if endotoxin (LPS) can mediate the production of inflammatory cytokines by enterocytes.

DESIGN

Laboratory experiment.

SETTING

Teaching hospital and burns unit, USA.

MATERIAL

Caco-2 cells (HTB38, human adenocarcinoma, and colon).

MAIN OUTCOME MEASURES

Concentrations of tumour necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6) and prostaglandin E2 (PGE2) in cell culture supernatants.

RESULTS

LPS significantly increased the production of TNF from 8.9 to 26.4 units/ml in 24 h and this increase persisted at a lower level for 4 days with an increase from 2.3 to 9 units/ml at a cell concentration of 2 x 10(5) cells/ml. There was no increase in TNF production when the cells were cultured at 5 x 10(5) cells ml with LPS. At a concentration of 2 x 10(5) cells/ml, the cells produced small amounts of IL-6 in 24 h or 4 day cultures with or without LPS. At a concentration of 5 x 10(5) cells/ml, LPS significantly increased IL-6 production in 24 h from 142 to 433 units/ml and from 106 to 250 units/ml in 4 days. The amount of IL-6 produced by LPS-stimulated cells was greater at 1 day than at 4 days. There was no significant difference in PGE2 production by the cells under any of the incubation conditions.

CONCLUSION

Enterocytes can produce TNF and IL-6, and endotoxin can increase the production of these cytokines by enterocytes. The gut therefore has the potential to become an important source of inflammatory cytokines.

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.

Impact of first acute rejection episode and severity of rejection on cadaveric renal allograft survival

A total of 504 renal transplants were performed between 1984 and 1993; 408 (81%) were cadaver grafts. This study evaluated the impact of a first acute rejection episode and the severity of the rejection on cadaveric allograft survival. Acute allograft rejection was based on clinical evaluation and confirmed by renal biopsy. Ten patients were excluded from this study due to early patient or graft loss. Patients were divided into Group I (n = 179), who never experienced acute rejection, and Group II (n = 219), who had an acute rejection episode. Group II patients were divided into IIA (n = 140), who had a mild first acute rejection episode treated with methylprednisolone, and IIB (n = 79), who had moderate or severe acute rejection treated with OKT3. The overall 1-, 2-, 3-, and 5-yr actuarial cadaveric renal allograft survival for Group I was 80%, 76%, 74%, and 68%. The corresponding graft survival for Groups IIA and IIB were 75%, 63%, 58%, and 50%; and 79% 71%, 65%, and 53% [p = 0.03 (I vs IIA), p = NS (I vs. IIB and IIA vs IIB)]. A similar pattern of survival was seen in primary kidney allograft recipients. In conclusion, long-term graft survival was superior in patients who never experienced acute rejection compared to those with rejection. Improvements in long-term graft survival can be accomplished in patients with severe rejection with OKT3 treatment resulting in comparable survival to those with mild rejection.

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.

Gastric bypass in morbidly obese kidney transplant recipients

Severe post-transplant obesity has previously been shown to have a negative impact on graft survival following kidney transplantation. It also contributes to late patient mortality and is associated with hypertension, diabetes and hyperlipidemia. We undertook Roux-en-Y gastric bypass (GBP) in three morbidly obese (200-260% ideal body weight) (IBW) patients 6-8 yr following kidney transplantation. Roux-en-Y gastrojejunostomy to a 30 ml stapled gastric pouch was created with the jejunojejunostomy (both loops) 80-120 cm from the ligament of Treitz. By 12 months post-GBP, weight loss plateaued at 100-150% IBW. Both patients that had developed post-transplant diabetes mellitus (PTDM) had complete resolution within 9 months following GBP. On average the patients required 3 less hypertension (HTN) medications after GBP; 2 of the 3 patients are now normotensive off medication. Improvements in hyperlipidemia were also shown. The absolute cyclosporine (CsA) requirement (mg/d) increased by approximately 33% (p = NS), and there was also a significant increase in the weight adjusted CsA requirement from 1.8 to 3.5 mg/kg/d (p = 0.02, ANOVA) following GBP in order to maintain similar TDX trough CsA levels. GBP offers significant reduction in weight, HTN, PTDM and hyperlipidemia in morbidly obese kidney transplant recipients. However, CsA dose requirements may increase after GBP as a consequence of the defunctionalized intestine.

An examination of tissue chimerism in the ACI to Lewis rat cardiac transplant model

While the existence of chimeric cells in host tissue following organ transplantation is well documented, its distribution, temporal evolution and relationship to allograft survival is less clear. To explore this phenomenon, Lewis recipients of ACI cardiac allografts representing a wide range of immunosuppressive protocols and graft survival times were examined for the presence of chimerism using a sensitive polymerase chain reaction assay. Four groups of animals were examined: untransplanted animals receiving donor specific transfusion (DST)/cyclosporine A (CsA); allograft recipients with no treatment; recipients treated with DST/CsA/supplementary immunosuppression with rejection at 21-183 days; and recipients sacrificed with functioning allografts, treated with DST/CsA/supplementary immunosuppression and surviving > 200 days. To elucidate variations in the tissue distribution of chimeric cells, bone marrow, skin, liver, spleen, and thymus were examined in each animal. Untransplanted animals receiving DST/CsA displayed no evidence of chimerism. In animals receiving a cardiac allograft but no treatment, there was extensive evidence of chimerism in four of five animals. Chimerism was also detected in seven of nine animals with intermediate graft survival at the time of rejection. In animals with long-term graft survival, only four of eight displayed chimerism. These results suggest that, without immunosuppression, early chimerism does not lead to prolonged graft survival and that, even when graft survival is moderately prolonged, these cells are not sufficient to prevent rejection. In conclusion, chimerism appears to be a common phenomenon following transplantation, is not a result of DST, and may not be necessary for maintenance of long-term graft survival.

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

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 10(a)111 in 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.

Production of cytokines and prostaglandin E2 by subpopulations of guinea pig enterocytes: effect of endotoxin and thermal injury

BACKGROUND

There is increasing evidence that cells other than immune cells have the potential for producing immunomediators. This study determined whether distinct populations of enterocytes from unburned and burned animals responded differently to endotoxin regarding production of tumor necrosis factor, interleukin-1 and -6 and prostaglandin E2.

METHODS

Three subpopulations of enterocytes, progressing from the villus tip towards the crypt, were obtained from washes of the small intestine. The cells were cultured in the presence of endotoxin, and the supernatants were assayed for the mediators.

RESULTS

Thermal injury primed all three populations of enterocytes to produce larger amounts of tumor necrosis factor and interleukin-6 compared to cells from unburned animals. Enterocytes that were nearer the crypt produced the largest amounts of the cytokines.

CONCLUSION

These observations may be important because, as gut integrity is compromised after thermal injury, enterocytes that may have previously been unexposed or less exposed to endotoxin can become a significant source of inflammatory cytokines.

The significance of timing of additional short-term immunosuppression in the donor-specific transfusion/cyclosporine-treated rat

It is hypothesized that the mechanism, or mechanisms, responsible for donor-specific transfusion (DST)/cyclosporine (CsA) immunosuppression is generated by an active immune response that is most dynamic in the immediate peritransplant period and thus might be at the peak of vulnerability to the influences of added immunosuppression. To better define this concept, four immunosuppressive drugs were combined with a d-1 DST and 14-day course of CsA in the ACl-to-Lewis cardiac transplant model. A 5-day course of antithymocyte globulin (ATG) initiated at d-1 or d+4 with DST/CsA reduced survival vs. DST/CsA alone (27.0 +/- 2.6 days and 24.6 +/- 5.7 days vs. 95.3 +/- 16.3 days, P<.05). Delay of initiation to d+7 improved survival to 39.5 +/- 8.9 days. A 5-day course of methylprednisolone (MP) begun at d-1 with DST/CsA decreased survival vs. DST/CsA alone, 59.2 +/- l0.0 days vs. 95.3 +/- 16.3 days, but delay to d+4 improved survival to 110 +/- l8 days, P<.05 vs d-1. A 3-day course of brequinar (Breq) begun at d-1 with DST/CsA increased survival to 244 +/- 48.6 days, while delay to d+4 reduced survival to 49.0 +/- 6.7 days, P<.05 vs. d-1. Finally, a 5-day course of rapamycin (Rapa), was given with d-1 DST/CsA treatment beginning on d-1, d0, d+l, d+3, d+5, and d+7. In this instance, no significant differences in survival were found between timing groups or DST/CsA control. Together, these data support the hypothesis that DST/CsA treatment generates an active immune response that is inhibited by early initiation of ATG or MP, enhanced by early administration of Breq, and unchanged by early administration of Rapa.

Detection of intestinal bacterial translocation using PCR

Microbial translocation has been suspected to be a major contributing factor in the development of sepsis of unknown origin and multiple organ failure syndrome, but there are currently no tests capable of detecting and quantitating translocation sequentially in humans. The purpose of this study was to develop a sensitive polymerase chain reaction (PCR) test to detect Escherichia coli (E. coli) DNA in the blood of animals after inducing bacterial translocation from the gut. DNA was extracted from blood and primers were used to amplify an 800-bp gene fragment of E. coli by 30-cycle PCR. Detection by southern blotting achieved a sensitivity of 10-100 organisms per 0.3 cc blood. Experimental groups included mice gavaged with 10(10) E. coli followed by 20% body surface area thermal injury, or no injury. Controls included burn only and no treatment groups. Blood was obtained by cardiac puncture 1 hr after burn. Cultures were done on blood samples from all groups. More animals in the burn/gavage group had positive bacterial cultures. All controls were culture negative. E. coli detection by PCR was 100% sensitive in culture positive animals with detection in the gavage/burn group higher than that in all other groups. PCR was negative for all mice without treatment. Several culture negative animals had detectable bacterial DNA by PCR. This highly sensitive and specific method can be used repeatedly to test the blood of patients for the presence of microbial DNA, which could be originating from the gut.

Rescue therapy with tacrolimus after combined kidney/pancreas and isolated pancreas transplantation in patients with severe cyclosporine nephrotoxicity

This study details 11 pancreas transplant recipients (10 combined kidney and pancreas and 1 pancreas after kidney) who were converted to tacrolimus (FK506) due to acute severe cyclosporine nephrotoxicity in 8 cases and persistent rejection with cyclosporine toxicity in three cases. Arteriolopathy was documented by renal histology in all cases. Cyclosporine was discontinued for 24 hr immediately prior to initiation of tacrolimus. Tacrolimus was started orally at 0.1 mg/kg twice daily with dose adjustments to maintain whole blood trough levels of 8-15 ng/mL by IMx. Tacrolimus was initiated a mean of 14.5 months (range 1-81) after pancreas transplantation. The mean serum creatinine level had increased to 2.9 mg/dl from 1.0 mg/dl at the diagnosis of cyclosporine arteriolopathy (P=0.003). The mean serum creatinine and blood glucose levels at the time of initiation of tacrolimus were 2.1 mg/dl and 104 mg/dl, respectively. Serum creatinine was 1.7 mg/dl, 1.9 mg/dl, 1.8 mg/dl, and 1.7 mg/dl after 1, 2, 3, and 6 months of tacrolimus therapy, respectively; ANOVA (P = 0.02). The corresponding blood glucose levels were 117 mg/dl, 112 mg/dl, 109 mg/dl, and 116 mg/dl, respectively (P=NS). Normal C-peptide levels were present before (5.9 ng/ml) and after (6.2 ng/ml), the initiation of tacrolimus therapy (P=NS), and mean HbA1C was 6.1% before and 6.3% after tacrolimus therapy, (P=NS). There were 4 episodes of acute rejection, 3 responded to intravenous methylprednisolone, and 1 required OKT3 during tacrolimus therapy. Reversible tacrolimus nephrotoxicity was noted in three patients without any evidence of progressive vasculopathy. All 11 patients are alive, and 10/11 kidney and pancreas grafts are functioning with a mean follow-up of 7.7 months (range 5-10). In this study, conversion from cyclosporine to tacrolimus in kidney and pancreas recipients resulted in improvement and stabilization of renal function while maintaining stable blood glucose, C peptide, and HbA1C levels.

Outcome of cadaveric renal transplantation by induction treatment in the cyclosporine era

A total of 358 cadaveric renal transplantations performed between 1984 and 1993 received induction therapy with Minnesota antilymphoblast globulin (MALG) 95, muromonab-CD3 (OKT3) 58, antithymocyte globulin--Upjohn (ATGAM) 104, rabbit antithymocyte serum (RATS) 37, or cyclosporine (CyA) 64. There were no differences in age, gender, HLA mismatches and maintenance immunosuppression between these groups of recipients. A significantly higher proportion of OKT3 induction patients were retransplants (50%, p < 0.0001). There were fewer diabetic recipients in the group that received RATS (8%) compared to the other groups (p = 0.0009). There was no significant difference in overall graft survival with the various forms of induction treatment (log rank test, p = 0.48). Similarly, primary cadaveric graft outcome was not different with various forms of induction treatment (p = 0.62). Acute rejection was higher with ATGAM, occurring in 65% of patients, compared to MALG (52%), OKT3 (55%), RATS (43%) and CyA (55%). A significantly lower number of patients were rejection-free with ATGAM (35%) compared to MALG (48%) (p = 0.04). Patients who received ATGAM induction also had a higher rate of rebound rejection. Patients receiving ATGAM induction had a significantly higher serum creatinine level at 1 and 6 months post-transplantation (p < 0.005) compared to other induction treatments. In conclusion, the prevalence of acute rejection was higher with ATGAM, which was also reflected by higher serum creatinine levels. However, the long-term graft function and survival were not different with the various induction treatments.

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.

Expanding the donor pool: use of marginal donors for solid organ transplantation

Organ transplantation has become a viable treatment for an increasing number of patients suffering from irreversible organ failure. In response to the steeply rising demand for transplantation, both the number of transplant centers and the number of patients on waiting lists have grown rapidly. Because organ donation has not kept pace with demand, each year a greater number of patients die while awaiting donor organs. (About 9% of all patients on the list in 1993 but not transplanted died. Death rates were highest, 19% and 16% respectively, for patients awaiting hearts and livers.) Among the factors contributing to the organ shortage are cultural and psychological barriers to donation and missed opportunities to request donation. An accompanying diminution in traumatic deaths of potential young donors has made older and other marginal, or higher-risk, donors the focus of studies on expansion of the donor pool. The studies reviewed herein evaluated donor risk factors such as age, disease (including infection), obesity, cold ischemia time, suboptimal organ function, and nontraumatic causes of death. Overall, broadened criteria for acceptable donor kidneys, hearts, and livers appear to lessen graft survival rates somewhat compared with rates for ideal donor organs. Nonetheless, use of higher-risk organs allows lifesaving transplants that could not otherwise be performed and results in acceptable prognoses for survival. Further research is needed to identify better tests for evaluating donor organs, provide longer-term follow-up of recipients of higher-risk organs, and develop alternative means to fill the donor-organ shortfall.

Organizational development strategies on nursing units

The organizational development process was evaluated on psychiatric units. Using a model of technostructural fit suggested by Alexander and Bauerschmidt, structural interventions were implemented. Insights on the use of organizational development in nursing are presented.

Effects of hyperoxia on bacterial translocation and mortality during gut-derived sepsis

BACKGROUND

While hyperoxia is commonly used for treating carbon monoxide poisoning, chronic nonhealing ulcers, acute traumatic and chronically ischemic wounds, and refractory osteomyelitis, its efficacy is unproven in numerous clinical situations, including treatment during severe sepsis.

OBJECTIVE

To test the effects of hyperoxia on bacterial translocation and mortality during gut-derived sepsis in a clinically relevant model of infection.

METHODS

Balb/c mice were gavaged with 10(9) Escherichia coli and subjected to a 20% burn injury. Then, the animals were randomized to receive hyperoxia for different periods of time. Survival and the extent of translocation were determined, as well as intestinal histologic features.

RESULTS

Hyperoxia treatment preserved gut morphology and improved gut barrier function, decreasing the amount of bacterial translocation. Short-term (4- or 8-hour) hyperoxia (100% oxygen) treatment improved survival only on day 1 after injury but did not affect the final outcome. Short-term (8-hour) hyperoxia (100% oxygen) plus 5-day 40% oxygen environment significantly improved long-term survival.

CONCLUSION

Tissue pO2 may be an important regulator of gut barrier function. Hyperoxia treatment appears to play a major role in preserving gut barrier function.

High doses of dietary arginine during repletion impair weight gain and increase infectious mortality in protein-malnourished mice

There is considerable evidence for the beneficial effects of dietary arginine, a conditionally-essential amino acid that enhances anabolism and T-cell function. However, the safety and efficacy of higher doses of arginine supplementation following infection have not been investigated completely. These issues were explored therefore, in a murine model of malnutrition and infection. Severe protein malnutrition was induced by feeding mice for 6 weeks on an isoenergetic diet containing only 10 g protein/kg. Mice were then allowed to consume diets with normal amounts of protein (200 g/kg) with 50 g/kg provided as amino acid mixtures of glycine and arginine in which the arginine content ranged from 0 to 50 g/kg. During the repletion period a significant weight gain was noted in the groups fed on diets with either 10 or 20 g arginine/kg, but not in the group fed on the diet with 50 g arginine/kg, compared with the diet with 0 g arginine/kg. Mortality rates after infection with Salmonella typhimurium were not decreased by the addition of 10 or 20 g arginine/kg to the diet, and were in fact worsened by supplementation with 50 g arginine/kg. The results of the present study showed that not only are the beneficial effects of arginine supplementation after infection lost when high doses are administered, but also that these high doses become toxic. Mice fed on higher doses showed significant impairment of weight gain and an increase in mortality rates.

Differential expression of intestinal and splenic cytokines after parenteral nutrition

OBJECTIVE

To determine the effect of parenteral nutrition (PN) on the expression of message for inflammatory cytokines in the spleen and different segments of the intestine.

DESIGN

Randomized controlled trial.

PARTICIPANTS

Eleven adult male Sprague-Dawley rats weighing 250 to 300 g.

INTERVENTIONS

All rats underwent central venous cannulation and were randomized to two groups. Group 1 (n = 6) received saline solution infusion and chow ad libitum; group 2 (n = 5) received lipid-free PN with no oral feeding. After 7 days, the animals were killed and the spleens and segments of small and large intestine were removed.

MAIN OUTCOME MEASURES

The expression of message for tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and IL-1 in the spleen and intestine was determined using a semiquantitative reverse transcription polymerase reaction. Splenic macrophages were isolated and cultured for 24 hours with and without lipopolysaccharide. Production of TNF-alpha and IL-6 was determined by bioassay followed by enzyme-linked immunosorbent assay.

RESULTS

After 7 days of infusion, messenger RNA (mRNA) expression for TNF-alpha, IL-1, and IL-6 was increased in the jejunum (P < .05), and TNF-alpha mRNA and IL-6 mRNA expression was decreased in the spleen (P < .01) of PN-fed animals when compared with saline/chow controls. In addition, TNF-alpha mRNA expression was increased in the cecum (P < .05), IL-1 mRNA expression was increased in the ileum (P < .05), and IL-6 mRNA expression was increased in the cecum (P < .05) and Peyer's patches (P < .007) in the PN-fed animals. Production of TNF-alpha and IL-6 by splenic macrophages was decreased following PN infusion in both lipopolysaccharide-treated and untreated cultures (P < .05).

CONCLUSIONS

Infusion of lipid-free PN induces a differential mRNA expression for inflammatory cytokines in the spleen and intestine with an overall up-regulation of the expression of inflammatory cytokines in the intestine and a down-regulation in the spleen. These data provide evidence that the regulatory mechanisms for cytokine production are different in the intestine and the spleen. Further study is needed to elaborate the mechanism of this differential expression following lipid-free PN infusion.

Anti-interleukin-6 antibody treatment improves survival during gut-derived sepsis in a time-dependent manner by enhancing host defense

OBJECTIVE

To determine the in vivo neutralizing activities of anti-interleukin-6 (IL-6) antibody on survival rate and host defense in a clinically relevant model of infection.

DESIGN

Prospective, randomized, experimental animal study.

SETTING

University and Shriners Burns Institute research laboratories.

SUBJECTS

Two hundred seventy-six adult, female Balb/c mice.

INTERVENTIONS

Balb/c mice were treated with 10 micrograms of antimurine IL-6 antibody, nonspecific murine immunoglobulin G (IgG), or placebo at 2, 4, or 8 hrs after they underwent bacterial challenge by gavage of 10(10) Escherichia coli and thermal injury. The survival rate was determined. The number of viable translocated bacteria, the total amount of translocation, and the percentage of bacteria that survived were also studied in different tissues.

MEASUREMENTS AND MAIN RESULTS

Survival rate after burn and gavage was significantly improved in animals treated with antimurine IL-6 antibody at 2 and 4 hrs but not at 8 hrs after injury compared with control animals treated with nonspecific IgG or saline. The IL-6 serum concentration was significantly lower after burn and gavage in the animals treated 2 and 4 hrs after injury compared with nontreated animals. Better killing of translocated bacteria was observed in the tissues of animals treated with antimurine IL-6 antibody 2 hrs after injury.

CONCLUSIONS

Treatment with antimurine IL-6 antibody at 2 and 4 hrs after injury, but not at 8 hrs after injury, positively affects outcome during gut-derived sepsis. Moreover, the beneficial effect of treatment after 2 hrs was related to an enhanced clearance of translocated bacteria.

Nutritional immunomodulation enhances cardiac allograft survival in rats treated with donor-specific transfusion and cyclosporine

The aim of this study was to assess the efficacy of an enteral diet fortified with arginine, RNA, and fish oil (Impact), alone and in combination with cyclosporine (CsA) and donor-specific transfusion (DST) on allograft survival in the ACI:Lewis rat cardiac transplant model. Animals were fed ad libitum with either standard rat chow or Impact diet. Six groups were studied; these consisted of untreated recipients fed either standard diet or Impact diet; recipients treated with CsA 10 mg/kg on the day prior to engraftment (day-1) followed by 2.5 mg/kg/d, day 0-->day+13 and fed with either standard diet or Impact; and animals given a DST (1 ml) on day-1, CsA as described previously and fed either standard diet or Impact. Untreated animals standard diet (group 1, n = 8) rejected their allografts at 7.0 +/- 0.0 days, while those fed Impact (group 2, n = 9) had graft survival of 12.8 +/- 2.1 days, (P = .01 versus group 1). Animals treated with CsA alone and standard diet (group 3, n = 9) rejected at 30.3 +/- 4.8 days, while the combination of CsA and Impact diet (group 4, n = 8) rejected at 33.0 +/- 9.5 days--minimally improved survival compared with group 3. Animals treated with DST/CsA and standard diet (group 5, n = 7) rejected at 72.1 +/- 6.8 days, while the substitution of Impact for standard diet (group 6, n = 8) led to a significant graft prolongation to 275 +/- 53 days, n = 8 (P < .015 vs. groups 1-5). These data suggest that Impact diet alone can have potent immunomodulatory properties but may require the addition of DST/CsA to realize its potential. These findings underscore the potential of dietary immunomodulatory therapy to prevent rejection and promote tolerance to solid organ allografts.

Administration of intragraft interleukin-4 prolongs cardiac allograft survival in rats treated with donor-specific transfusion/cyclosporine

It has been hypothesized that immunoregulating cytokines produced by intragraft Th-2 cells may be important for prolonged allograft survival. ACI hearts transplanted into untreated Lewis rat recipients survived for 6.2 days, but they survived for 72.1 days in recipients treated with a donor-specific transfusion and low dose CsA for 14 days. In donor-specific transfusion/CsA-treated animals, intragraft infusion of IL-10 via a 14-day osmotic minipump had no effect on graft survival (75.6 days), but intragraft infusion of IL-4 prolonged graft survival to 149.2 days (P < 0.01). While the actual mechanism of this effect is unclear, it suggests that IL-4 may be important in the development of long-term graft survival.