Epidermal growth factor regulates intestinal glutamine uptake during total parenteral nutrition

Sprague Dawley rats were randomised into three groups: group I (chow) were fed rat chow and water ad libitum, group II total parenteral nutrition (TPN) received a standard formula of TPN, and group III (TPN--epidermal growth factor (EGF)) received the same TPN as group II and injections of EGF (0.1 microg/gm body weight) subcutaneously twice daily. Glutamine (GLN) concentrations in tissues and blood were measured by reversed phase high performance liquid chromatography. Gut GLN extraction was calculated by dividing the difference in GLN concentrations (Conc) between the carotid artery (ART) and portal vein (PV) by the arterial concentration [(ART Conc - PV Conc)/ART Conc]. TPN induced a marked reduction of GLN concentration in tissues and blood, and also reduction of gut GLN extraction. When EGF was administered along with TPN, gut GLN concentration did not fall and gut GLN extraction was increased by 15% (TPN - EGF 1 week, P < 0.05). Arterial blood concentration of GLN was increased when TPN and EGF were used for 1 week (P < 0.05 vs control). But EGF did not prevent the GLN concentration of other tissues decreasing during TPN. Our results suggest that EGF can regulate intestinal uptake of GLN during TPN.     

A parenteral nutrition regimen with ornithine substituted for arginine alters the amino acid,but not polyamine,content of the ward colon tumor

Substituting ornithine for arginine in total parenteral nutrition (TPN) regimens eliminates the TPN‐enhanced growth of the Ward colon tumor. Plasma arginine was increased when tumor growth was increased, suggesting a role for this amino acid. The erythrocyte polyamine content, however, was elevated in rats receiving both TPN regimens, indicating an increased synthesis and availability for tumors receiving arginine‐ and ornithine‐containing regimens. The objective of this study, therefore, was to evaluate the effect of substituting ornithine for arginine in a TPN regimen on the amino acid and polyamine content of the Ward colon tumor compared with that of rats fed chow ad libitum. Male Fischer 344 rats with a transplantable Ward colon tumor implanted subcutaneously were randomized to three groups and fed for four days. One group received a TPN regimen with arginine (1,300 mg/100 ml, ENA), whereas a second group received a regimen with an isonitrogenous substitution of ornithine (ENO). A control group received chow ad libitum. Serum and tumors were evaluated for arginine, ornithine, lysine, and polyamine content. The arginine concentration in the serum and tumor increased when rats received ENA. In contrast, the serum and tumor arginine content for rats receiving ENO was significantly lower than that for rats receiving chow or ENA. Tumor and serum ornithine content was increased severalfold when ornithine was included in the regimen. Tumor polyamine content was not affected by TPN. The results show that serum and tumor arginine content are significantly altered by substituting ornithine for arginine in a TPN regimen. These and previous results suggest that TPN‐enhanced growth of the Ward colon tumor when arginine is included in the formulation occurs by a mechanism other than increased polyamine synthesis.     

精氨酸对全胃肠外营养大鼠肝脂肪变性的保护作用

目的：探讨精氨酸在全胃肠外营养引起的肝脂肪变性中的作用。方法：１８只正常Ｗｉｓｔａｒ大鼠随机分类三组：Ａ组,自由进食和水;Ｂ组,ＴＰＮ;Ｃ组,ＴＰＮ＋精氨酸。实验７天后测体重、肝功能、门脉胰岛素、胰高血糖素、肝重、肝内脂肪和肝组织学检查。结果：Ｂ组门静脉胰岛素与胰高血糖素比值较Ａ组升高,Ｃ组门静脉Ｉ／Ｇ值较Ｂ组降低。Ｂ组肝内脂肪较Ａ组增加,Ｃ组肝内脂肪较Ｂ组减少。结论：精氨酸可以减少ＴＰＮ引起的肝     

Selective bowel decontamination, nutritional therapy and bacterial translocation after burn injury

We studied the influence of selective bowel decontamination (SBD) with neomycin, on bacterial translocation (BT) in rats treated with early post-burn parenteral nutrition (TPN) or enteral nutrition (TEN). Male Wistar rats were randomly assigned to receive either TPN (groups 1, 2) or an isonitrogenous, isocaloric polymeric diet (TEN, groups 3, 4) or a standard rat chow ad libitum (group 5), for 5 days after burn injury (30% b. s. area). In addition, groups 1 and 3 received a daily oral dose of neomycin (30 mg/kg) during the same period. At the end of the study, animals were killed and the mesenteric lymph nodes (MLN), liver (L) and spleen (S) were removed for microbiological cultures. The overall incidence of BT was MLN: 67%, L: 58% and S: 42% with a mortality rate of 12.2% In MLN and L, group 5 showed significantly less BT than groups 1 and 2 (30% vs 84%, p < 0.02) and groups 3 and 4 (38% vs 76%, p < 0.05), respectively. No differences were found between TPN and TEN groups. SBD (groups 1 and 3) resulted in a significantly lower mortality rate (26% vs 0%, p < 0.05) and BT in the liver (38% vs 100%, p < 0.001) than rats without antibiotic treatment (groups 2 and 4). It is concluded that early post-injury TPN or TEN promote BT to a greater extent than a standard chow. In addition, SBD with neomycin prevents mortality and BT after burn injury.     

精氨酸增强全肠外营养对急性胰腺炎大鼠肠粘膜屏障的影响

目的：探讨精氨酸增强精氨酸增强ＴＰＮ对急性胰腺炎（ＡＰ）大鼠肠粘膜屏障的影响。方法：雄性ＳＤ大鼠６４只，随机分成：①对照组（ｎ＝１６）；②ＡＰ组（ｎ＝１６）；③ＡＰ＋ＴＰＮ组（ＴＰＮｓ组ｎ＝１６）；④ＡＰ＋ＴＰＮ＋精氨酸组（ＴＰＮａ组ｎ＝１６）。分别于建立急性胰腺炎模型后第１及第５天剖杀每组８只大鼠取材，检测肠粘膜一氧化氮（ＮＯ）、丙二醛、蛋白质含量、肠系膜淋巴结及门静脉血细菌移位率。结果：与对照组比较，术后１天及５天时，ＡＰ组肠粘膜丙二醛焦点量及肠系膜淋巴结细菌移位率显著升高；５天时蛋白质含量显著降低，而门静脉血细菌移位率明显升高。与ＴＰＮｓ组比较，ＴＰＮａ组１天时肠粘膜ＮＯ含量即明显升高；肠系膜淋巴结细胞移位率显著降低；５天时肠粘膜ＮＯ与蛋白质含量均显著升高；丙二醛含量显著降低。结论：急性胰腺炎可引起肠粘膜     

表皮生长因子增强TPN减少放射性肠炎细菌易位及其机理的实验研究

腹部受辐射 ( abdominal rdiation,AR)致放射性肠炎常导致肠粘膜屏障损害和细菌易位。接受长期 TPN( total parenteral nutrition,TPN)改善营养的同时 ,可加重细菌易位 ,并导致多器官功能衰竭等致死性并发症。即使给予肠粘膜代谢所需的谷氨酰胺 ( Glutamine,Gln)亦不能完全防治其损伤。EGF( epidermal growth factor)是胃肠道粘膜上皮生长和增殖的介质。本研究在 SD大鼠放射性肠炎模型上观察了 EGF增强 TPN对放射性肠炎细菌易位及对损伤的肠粘膜修复的影响 ,结果发现 ,经 EGF增强的 TPN治疗大鼠放射性肠炎 ,大鼠死亡率、细菌易位率均较不用 TPN及应用不含 EGF的 TPN组明显下降 ,体重、粘膜 /肠段重量比、绒毛高度、面积、小肠 Gln摄取率及 DNA含量均明显升高。机理为 :EGF对小肠粘膜有明显的滋养作用。EGF增强 TPN在提供较完善营养及肠道充分休息 ,促进创伤愈合的同时 ,通过提高肠粘膜对 Gln的摄取能力 ,维持肠粘膜上皮的正常代谢 ,加速修复损伤的肠粘膜屏障 ,降低细菌易位率 ,从而降低死亡率     

Clenbuterol treatment increases muscle mass and protein content of tumor-bearing rats maintained on total parenteral nutrition

Treatment of tumor-bearing (TB) and control rats with the anabolic beta-2 agonist drug clenbuterol (CLE) for 14 days reduced food intake for 4 days initially. Feeding was increased in anorectic TB rats, however, during the last 7 days of drug administration. Since minimal muscle savings were observed in chow-fed TB rats treated with CLE, the anabolic effects of this drug were investigated in a second experiment on TB rats maintained on total parenteral nutrition (TPN). Sixteen days after the subcutaneous transplantation of methylcholanthrene-induced sarcomas rats was begun on a 2-week schedule of TPN. One group of these rats was treated daily for 14 days with CLE, while the remaining rats received injections of saline. Additional groups of TB and nonTB rats were maintained on rat chow for this period and treated with saline. Although TB rats maintained on rat chow or TPN and treated with saline exhibited significantly decreased gastrocnemius muscle weight and protein content, treatment of TB-TPN rats with clenbuterol normalized muscle mass and increased muscle protein content significantly and increased plasma concentrations of branched-chain amino acids. These results indicate that although nutritional support of TB organisms does not result in protein repletion, the addition of an anabolic drug renders the nutritional support highly efficacious.     

Effects of alanyl-glutamine on intestinal adaptation and bacterial translocation in rats after 60% intestinal resection

The effects of alanyl-glutamine dipeptide (Ala-Gln)-enriched parenteral nutrition on intestinal mucosa and gut barrier function were investigated. Wistar rats were studied. After moderate surgical stress was induced by 60% resection of the small intestine, the rats were randomized to three groups: the chow group was given standard rat chow; the PN group received standard parenteral nutrition (PN); and the Ala-Gln group received glutamine dipeptide-enriched parenteral nutrition (3% Ala-Gln). Rats were maintained on their respective diets for 8 days. The chow and Ala-Gln groups maintained serum glutamine concentrations, intestinal mucosal thickness and villus height. Bacterial translocation rates in the chow and Ala-Gln groups were 20%, which was significantly less than that in the PN group (70%, P < 0.05). The results indicated that Ala-Gln-enriched parenteral nutrition maintains intestinal adaptation and gut barrier function after massive intestinal resection and parenteral nutrition.     

Effects of three intravenous lipid emulsions on the survival and mononuclear phagocyte function of septic rats

The immunosuppressive effects of intravenous lipid emulsions are a matter of great concern and debate. In a rat model of gram-negative bacteremia, we assessed whether the use of three intravenous lipid emulsions with different triacylglycerol compositions could influence mortality, bacterial clearance, and prostaglandin E(2) (PGE(2)) levels and compared these groups with groups of orally fed rats and rats that received a small amount of calories in form of glucose without enteral feeding (starvation).RATS WERE ASSIGNED TO ONE OF FIVE GROUPS: group 1 (control, n = 15) received rodent chow ad libitum and saline infusion; group 2 (starvation group, n = 12) had no access to chow and received an infusion of 5% glucose; group 3 (n = 17) received total parenteral nutrition (TPN) with long-chain triacylglycerols; group 4 (n = 12) received TPN with medium- and long-chain triacylglycerols; and group 5 (n = 15) received TPN with its emulsion based on olive oil. Animals received isonitrogenous and isocaloric TPN. After 2 d of TPN, a dose of 10(8) colony-forming units of Escherichia coli was introduced via the venous catheter; 2 d later the animals were killed. Blood, spleen, liver, and lungs were cultured. Circulating levels of PGE(2) were measured.Bacterial growth in the liver and lungs were significantly higher in groups 3 and 4 than in group 1, with no differences among the other groups. Rates of bacteremia were significantly higher in groups 3 and 4 than in group 1, with no differences among the other groups. Plasma levels of PGE(2) did not differ, and mortality was unaffected.Bacterial clearance clearly was preserved in orally fed, control rats when compared with rats on TPN with long-chain triacylglycerols or medium- plus long-chain triacylglycerols. However, the use of a lipid emulsion enriched intravenously with oleic acid was a valid way of reducing this disturbance, although plasma levels of PGE(2) and survival were not modified.     

Translocation of Salmonella typhimurium in rats on total parenteral nutrition correlates with changes in intestinal morphology and mucus gel

OBJECTIVE: We tested whether alterations in intestinal morphology and mucus gel correlate with differences in Salmonella typhimurium translocation between rats treated with total parenteral nutrition (TPN) and rats given a diet of chow. METHODS: Twenty-seven male Wistar rats were assigned to one of two groups: one received TPN for 14 d and the other (control) received standard rat chow and water ad libitum. Salmonella typhimurium (5 x 10(8) cells; GIFU 12142) was injected into a closed ileal loop. Portal venous blood (PVB), inferior vena cava blood (IVCB), and mesenteric lymph nodes (MLNs) were sampled for evaluation of bacterial translocation. Sections of the loop were prepared and stained with hematoxylin and eosin, periodic acid-Schiff (PAS), and fluorescein isothiocyanate-labeled Ulex europaeus agglutinin I (FITC-UEA-I) for image analysis. Perimeter, mucosal thickness, villus area, and positively stained mucus area were measured. A fluorescent antibody study was also done. RESULTS: Organisms were found in cultures of 1 in 13 control rats and 9 in 14 TPN rats. There were more bacteria in MLNs than in PVB or IVCB. There was no increase in the number of bacteria over time in PVB, IVCB, or MLNs. Perimeter and villus area (P < 0.001) and mucosal thickness (P < 0.01) were significantly smaller in the TPN group than in the control group. The positively stained mucus area was significantly smaller in the TPN group than in the control group (P < 0.05 with PAS, P < 0.01 with FITC-UEA-I). Salmonella typhimurium invaded specifically through Peyer's patches. In all culture-negative samples, bacteria were trapped by the mucous layer, with a very small number attached to the epithelial surface. CONCLUSION: Significant villous atrophy and reduction of mucus play an important role in the rapid translocation of S. typhimurium through Peyer's patches in rats after 2 wk of TPN.     

Total parenteral nutrition supplementation with glutamine improves survival after gut ischemia/reperfusion

BACKGROUND: Total parenteral nutrition (TPN) alters gut cytokines and mucosal immunity and increases intercellular adhesion molecule-1 (ICAM-1) expression, gut neutrophil levels, and mortality after gut ischemia. Supplementation of TPN with glutamine partially supports mucosal immunity by preserving respiratory and intestinal IgA levels, maintaining the proper IgA-stimulating cytokine milieu within the intestine, and reducing intestinal ICAM-1 expression and neutrophil accumulation. This work investigates whether glutamine supplementation of TPN affects mortality in mice after gut ischemic insult. METHODS: Thirty-eight mice were randomized to receive chow, TPN, or 2% glutamine-supplemented TPN (GLN-TPN) for 5 days. After feeding their respective diets, gut ischemia/reperfusion (I/R) was induced with superior mesenteric artery occlusion for 30 minutes followed by resuscitation with 1 mL saline. Survival was recorded until 72 hours after reperfusion. RESULTS: Survival time was significantly reduced in the TPN-fed mice compared with both chow-fed and GLN-TPN-fed mice (p < .05). Survival at 72 hours after reperfusion was also significantly lower in the TPN-fed mice than in the chow-fed and GLN-TPN-fed mice (p < .05) CONCLUSIONS: Glutamine supplementation of TPN significantly improves survival after gut I/R, suggesting modulation of the inflammatory response or improved gut tolerance to low-flow states.     

Urogastrone reduces gut atrophy during parenteral alimentation

Urogastrone (UG) exerts trophic effects on the intestine and may play a role in maintaining normal intestinal structure and function. Since administration of nutrients parenterally results in intestinal hypoplasia and hypofunction, the aim of this study was to determine the effects of UG on intestinal structure and function in parenterally fed rats. Central venous catheters were placed into 28 Sprague-Dawley rats. Group I (n = 10) received TPN alone. Group II (n = 8) received TPN and 15 micrograms/day of UG and group III (n = 10) received rat chow ad libitum. The animals that received urogastrone had significantly greater (p less than 0.05) intestinal weight (25.6 +/- 2.5 mg/cm vs 22.6 +/- 3.0 mg/cm), mucosal weight (8.4 +/- 1.4 mg/cm vs 6.2 +/- 0.9 mg/cm), mucosal protein content (6.2 +/- 1.7 mg/cm vs 2.7 +/- 0.6 mg/cm), villous height (427 +/- 27 microns vs 293 +/- 75 microns), crypt cell production rate (14.5 +/- 1.4 metaphases/hr vs 12.3 +/- 0.7 metaphases/hr) and sucrase specific activity (6.5 +/- 2.6 vs 3.7 +/- 2.0) than animals receiving only TPN. However, these parameters remained less than in chow-fed animals. Thus, simultaneous infusion of UG prevents, in part, intestinal hypofunction and hypoplasia which occurs during TPN. This may be due to maintenance of mucosal proliferative activity and brush border enzyme activity.     

Glutamine-enriched total parenteral nutrition maintains intestinal interleukin-4 and mucosal immunoglobulin A levels

BACKGROUND: Total parenteral nutrition (TPN) prevents progressive malnutrition but fails to maintain intestinal gut-associated lymphoid tissue (GALT) or established respiratory antiviral or antibacterial mucosal immunity. Our previous work demonstrated that decreases in intestinal immunoglobulin A (IgA) were associated with decreases in Th2-type IgA-stimulating cytokines, interleukin (IL)-4 and IL-10. Because glutamine supplementation of TPN partially preserves respiratory defenses and normalizes GALT, we investigated the ability of parenteral glutamine to normalize respiratory and intestinal IgA levels and measured Th2 cytokines in intestinal homogenates. METHODS: Animals were cannulated and randomly assigned to receive chow (n = 17), TPN (n = 18), or an isonitrogenous, isocaloric TPN solution formulated by removing the appropriate amount of amino acids and replacing them with 2% glutamine (n = 18) for 5 days. Respiratory tract and intestinal washings were obtained for IgA and the intestine homogenized and analyzed for IL-4 and IL-10. RESULTS: TPN decreased intestinal and respiratory IgA in association with decreases in intestinal IL-4 and IL-10 compared with chow-fed animals. Glutamine significantly improved respiratory and intestinal IgA levels, significantly improved IL-4 compared with TPN animals, and maintained IL-10 levels midway between chow-fed and TPN animals. CONCLUSIONS: Glutamine-enriched TPN preserved both extraintestinal and intestinal IgA levels and had a normalizing effect on Th2-type IgA-stimulating cytokines.     

The effect of immunonutrition on bacterial translocation,and intestinal villus atrophy in experimental obstructive jaundice

BACKGROUND & AIMS: Spontaneous bacterial infection and septicemia due to increased bacterial translocation (BT) in patients with obstructive jaundice result in significant morbidity and mortality. The present study evaluates the effects of enteral nutrition with immune enhancing feeds on BT and intestinal villus histopathology promoted by obstructive jaundice. METHODS: Fifty male Wistar-albino rats weighing 250-300g were assigned into five equal groups of 10. Animals in Groups I, II, and III were fed with standard chow, those in Group IV were given glutamine 1g/kg/day and the remaining 10 animals in Group V were fed with an arginine, omega-3 fatty acids, and RNA-supplemented enteral diet for (1g/kg/day amino acid and 230 kcal/kg) 7 days preoperatively. Group I underwent sham operation and the remaining animals in all other groups underwent common bile duct ligation. After operation, Group I had standard chow, Groups II and IV had glutamine, Groups III and V had an arginine omega-3 fatty acids, and RNA-supplemented enteral diet for 7 days. All animals were sacrificed on the 8th postoperative day and evaluated both biochemically and histopathologically. Samples from blood, liver, mesenteric lymph nodes and spleen were cultured under aerobic conditions. RESULTS: Significantly less BT was observed in groups fed with an arginine, omega-3 fatty acids, and RNA-supplemented enteral diet or glutamine in pre-and postoperative periods as compared to others (P<0.001). Histologic evaluation also showed significant reduction in villus atrophy in these groups. CONCLUSIONS: Enteral immunonutrition using glutamine or arginine, omega-3 fatty acids, and RNA-supplemented enteral diet during both pre-and postoperative periods seems to reduce BT and decrease atrophy of intestinal mucosal villi in rats with obstructive jaundice.     

Partial Enteral Nutrition Preserves Elements of Gut Barrier Function,Including Innate Immunity,Intestinal Alkaline Phosphatase (IAP) Level,and Intestinal Microbiota in Mice

Lack of enteral nutrition (EN) during parenteral nutrition (PN) leads to higher incidence of infection because of gut barrier dysfunction. However, the effects of partial EN on intestina linnate immunity, intestinal alkaline phosphatase (IAP) and microbiota remain unclear. The mice were randomized into six groups to receive either standard chow or isocaloric and isonitrogenous nutritional support with variable partial EN to PN ratios. Five days later, the mice were sacrificed and tissue samples were collected. Bacterial translocation, the levels of lysozyme, mucin 2 (MUC2), and IAP were analyzed. The composition of intestinal microbiota was analyzed by 16S rRNA pyrosequencing. Compared with chow, total parenteral nutrition (TPN) resulted in a dysfunctional mucosal barrier, as evidenced by increased bacterial translocation (p < 0.05), loss of lysozyme, MUC2, and IAP, and changes in the gut microbiota (p < 0.001). Administration of 20% EN supplemented with PN significantly increased the concentrations of lysozyme, MUC2, IAP, and the mRNA levels of lysozyme and MUC2 (p < 0.001). The percentages of Bacteroidetes and Tenericutes were significantly lower in the 20% EN group than in the TPN group (p < 0.001). These changes were accompanied by maintained barrier function in bacterial culture (p < 0.05). Supplementation of PN with 20% EN preserves gut barrier function, by way of maintaining innate immunity, IAP and intestinal microbiota.     

Pretreatment with citrulline improves gut barrier after intestinal obstruction in mice

Background: Citrulline has been shown to be an important marker of gut function, regulator of protein metabolism, and precursor of arginine. The authors assessed the effects of citrulline on gut barrier integrity and bacterial translocation (BT) in mice undergoing intestinal obstruction. Methods: Mice were divided into 3 groups: sham, intestinal obstruction (IO), and citrulline (CIT). The CIT group received a diet containing 0.6% citrulline; the IO and sham groups were fed a standard chow diet. On the eighth day of treatment, all animals received a diethylenetriamine pentaacetic acid (DTPA) solution labeled with ^99mTechnetium (^99mTc‐DTPA) by gavage for the intestinal permeability study. Terminal ileum was ligated except the sham group, which only underwent laparotomy. After 4, 8, and 18 hours, blood was collected to determine radioactivity. Samples of ileum were removed 18 hours after intestinal obstruction for histological analysis. In another set of animals, BT was evaluated. Animals received 10⁸ CFU/mL of ^99mTc–Escherichia coli by gavage; 90 minutes later, they underwent ileum ligation. Intestinal fluid and serum were collected to measure sIgA and cytokines. Results: The CIT group presented decreased intestinal permeability and BT when compared with the IO group (P < .05). Histopathology showed that citrulline preserved the ileum mucosa. The sIgA concentration was higher in the CIT group (P < .05). The IO group presented the highest levels of interferon‐γ (P < .05). Conclusions: Pretreatment with citrulline was able to preserve barrier integrity and also modulated the immune response that might have affected BT decrease.     

Bulk prevents bacterial translocation induced by the oral administration of total parenteral nutrition solution

The effects of a fat and glutamine-free orally administered total parenteral nutrition (TPN) solution on intestinal mucosal mass, morphology, barrier function, and cecal bacterial population levels were measured in CD-1 mice. Ileal mucosal protein content decreased by 63% (p less than 0.01) in the oral TPN-fed mice, although they gained weight on this diet. These TPN-fed mice also exhibited changes in mucosal structure and the normal ecology of their cecal microflora was disrupted leading to overgrowth with Gram-negative enteric bacilli. These changes in intestinal mucosal mass, morphology, and gut bacterial ecology were associated with an increased incidence of bacterial translocation (BT) (TPN group 70% BT vs control group 15% BT: p less than 0.01). The administration of cellulose fiber or kaolin (bulk-forming agents), but not of citrus-pectin (a fully-fermentable, nonresidue fiber) reduced the incidence of BT in the TPN-fed mice to control levels. The beneficial effects of these bulk-forming agents appeared to be due to their ability to prevent TPN-induced disruption of the intestinal microflora and alterations in intestinal morphology, even though they did not prevent ileal mucosal protein levels from decreasing. These results suggest that the administration of bulk forming agents will prevent the loss of intestinal barrier function against luminal bacteria that occurs in mice fed an oral TPN solution.     

Effects of arginine-enriched total parenteral nutrition on inflammatory-related mediator and T-cell population in septic rats

OBJECTIVES: Previous reports have shown that oral arginine (Arg) has immune-enhancing properties in injury. However, the effects of parenterally infused Arg on sepsis are not well understood. We used a septic rat model to study Arg infusion in inflammatory-related cytokines and blood T lymphocyte population in vivo. METHODS: Rats with internal jugular catheters were assigned to one of two groups. Both groups received isonitrogenous total parenteral nutrition (TPN) supplemented with 270 mg of nitrogen per kilogram per day as Arg or glycine (Gly). TPN provided 270 kcal/kg of body weight, and the kilocalorie:nitrogen ratio was 143:1. TPN was maintained for 5 d plus 2, 4, or 6 h or 6 d, according to the scheduled deaths of the rats. On day 5, sepsis was induced by cecal ligation and puncture (CLP). After CLP for 2, 4, 6, and 24 h, rats were killed. RESULTS: The results showed that interleukin-1beta and tumor necrosis factor-alpha concentrations in peritoneal lavage fluid at 6 h and interleukin-6 levels at 24 h after CLP in the Gly group were significantly higher than those in the Arg group. The T-lymphocyte population in blood showed that CD8(+) suppressor T-cell number was significantly higher in the Gly group than in the Arg group at 6 h after CLP. The blood CD4(+):CD8(+) ratio was significantly higher in the Arg group than in the Gly group at 24 h after CLP. A negative nitrogen balance was observed in the Arg and Gly groups after CLP; there was no significant difference in nitrogen balance between the septic groups. No difference in survival rate at 24 h after CLP was observed between the groups. CONCLUSIONS: The results showed that, compared with the Gly group, TPN preinfused with Arg reduces the production of inflammatory mediators at the site of injury and that cellular immunity is enhanced at 24 h after CLP. Parenterally administered Arg had no beneficial effect in preventing nitrogen loss and improving survival in septic rats. Whether Gly has specific effects that reduce the effects of Arg require further investigation.     

Effects of arginine supplementation on mucosal immunity in rats with septic peritonitis

BACKGROUND: Supplemental Arginine (Arg) has been demonstrated to improve the immunologic response and reduce mortality in rodents with sepsis. However, the effects of Arg on gut-associated lymphoid tissue function after infection and sepsis are not clear. The aim of this study was to study the effect of Arg-supplemented diets before and Arg-enriched total parenteral nutrition (TPN) after sepsis or both on the intestinal immunity of rats with septic peritonitis. METHODS: Rats were assigned to four groups. Groups 1 and 2 were fed a semipurified diet, while in the diets of groups 3 and 4, part of the casein was replaced with Arg. After feeding the experimental diets for 10 days, sepsis was induced by cecal ligation and puncture (CLP); at the same time, the internal jugular vein was cannulated. All rats were maintained on TPN for 3 days. Groups 1 and 3 were infused with conventional TPN, while groups 2 and 4 were given a TPN solution supplemented with Arg, which replaced 10% of the total amino acids. All rats were sacrificed 3 days after CLP. Intestinal immunoglobin (Ig) A levels, total lymphocyte yields, and lymphocyte subpopulations in Peyer's patches were analyzed. In vitro cytokine secretion by splenocytes and Peyer's patch lymphocytes were also measured. RESULTS: Total lymphocyte yields in Peyer's patches, and small intestinal immunoglobulin A (IgA) secretion in group 4 were significantly higher than the groups 1 and 2. No differences were observed between groups 3 and 4. There were no differences in the interleukin (IL)-2 and interferon- gamma levels among all groups when splenocytes were stimulated with mitogen. However, in vitro splenocyte IL-10 production in group 4 was significantly higher than those of groups 1 and 2, and had no difference from group 3. There were no differences in the ratios of B and T lymphocyte subpopulations in Peyer's patches among all groups. CONCLUSIONS: Enteral Arg supplementation before sepsis tended to enhance total lymphocyte yields in Peyer's patches and intestinal IgA secretion. Arg administered both before and after CLP had a synergistic effect on improving intestinal immunity, possibly by enhancing systemic IL-10 secretion. However, intravenous Arg administration after CLP had no favorable effects on mucosal immunity in rats with septic peritonitis.     

Enteral feeding preserves gut Th-2 cytokines despite mucosal cellular adhesion molecule-1 blockade

BACKGROUND: Parenteral nutrition (PN) decreases gut-associated lymphoid tissue (GALT), the intestinal IgA stimulating cytokines IL-4 and IL-10 in gut homogenates, intestinal IgA levels and the expression of Peyer patch (PP) mucosal cellular adhesion molecule-1 (MAdCAM-1), an adhesion molecule found on the high endothelial venules of PP and other tissues. IL-4 in PP stimulates MAdCAM expression in vitro. MAdCAM-1 blockade with MECA-367 reduces GALT cell populations to PN levels but maintains intestinal IgA levels if the animals are chow fed. This study compares IL-4 levels in PP of chow and PN fed mice and measures the effects of MAdCAM blockade on IL-4 and IL-10 levels in gut homogenates of chow fed mice. We hypothesized that in vivo IL-4 levels drop in PP of PN fed mice and IL-4 and IL-10 levels are maintained after MAdCAM-1 blockade in chow fed mice. METHODS: Exp 1: 18 mice received chow or PN for 5 days to determine PP IL-4 levels. Exp 2: 44 mice were randomized to chow + control monoclonal antibody (mAb), chow + MECA-367 (anti-MAdCAM-1 mAb) or PN for 4 days before measurement of IL-4 and IL-10 levels in gut homogenates. RESULTS: Exp 1: IL-4 levels in vivo were lower in PP of PN-fed mice than chow fed mice (92.0 +/- 15.1 pg/mL vs 251.1 +/- 14.8, p = .0003). Exp 2: IL-4 levels were significantly higher in chow + control mAb (187.1 +/- 44.1 pg/mL) and chow + MECA-367 (110.9 +/- 19.1 pg/mL) groups than PN mice (21.8 +/- 30.6 pg/mL, p < .02 vs chow + control or chow + MECA-367). IL-10 levels were significantly lower with PN (23.1 +/- 40.9 pg/mL) with chow+control (174.0 +/- 22.2 pg/mL p < .01), or chow + MECA-367 (181.7 +/- 23.1 pg/mL, p < .02 vs PN). CONCLUSIONS: PN-feeding reduces in vivo IL-4 levels in PP (consistent with lowered MAdCAM-1 expression) and IL-4 and IL-10 levels in gut homogenates compared with chow. Despite MAdCAM-1 blockade, enteral feeding preserved gut IL-4 levels and increased IL-10 levels consistent with preserved IgA levels.