Glycyl-glutamine-enriched long-term total parenteral nutrition attenuates bacterial translocation following small bowel transplantation in the pig

Nutritional Risk of Candidates for Simultaneous Pancreatic-Kidney Transplantation-A Narrative Review

INTRODUCTION

Not much is known about the significance of nutritional status and support in transplant surgery, least of all in simultaneous pancreatic and kidney transplantation. Malnutrition in the context of simultaneous pancreatic-kidney transplantation seems to be complex and a still poorly investigated problem. Since SPKTX is highly qualified and also has a small volume procedure, it is difficult to obtain data from large cohorts of patients. The aim of this article is to gather existing evidence and information about the subject, as well as to elicit some questions and goals for the future.

METHODS

We searched through the Pub-Med database using the keywords "pancreas and kidney transplantation" combined with "nutritional risk", "nutritional status", "malnutrition", "nutritional intervention", and "frailty", finding a total of 4103 matching results. We then narrowed it down to articles written in English with the full text available. We also researched through the references of articles most accurately matching our researched terms.

RESULTS

There are numerous tools that have been investigated for the screening of malnutrition, such as the NRI index, PNI index, NLR, SGA scale, and NRS-2002 scale, each of which proved to be of some use in predicting patient outcomes in different surgical settings. Since all of them differed in components and assessed parameters and, in the absence of more sensitive or infallible indicators, the most reasonable approach seems to evaluate them jointly.

CONCLUSION

It is important to underline the necessity of nutritional screening and the subsequent introduction of adequate therapy while awaiting transplantation in an attempt to improve results. Considering the complexity of surgical procedures and the severity of underlying diseases with their intense metabolic components, the patient's nutritional status seems to significantly influence results. Consequently, nutritional risk assessments should be a part of the routine care of patients qualified for transplantation.

Mechanisms of Regulation of Transporters of Amino Acid Absorption in Inflammatory Bowel Diseases

Intestinal absorption of dietary amino acids/peptides is essential for protein homeostasis, which in turn is crucial for maintaining health as well as restoration of health from significant diseases. Dietary amino acids/peptides are absorbed by unique transporter processes present in the brush border membrane of absorptive villus cells, which line the entire length of the intestine. To date, the only nutrient absorptive system described in the secretory crypt cells in the mammalian intestine is the one that absorbs the amino acid glutamine. Majority of the amino acid transporters are sodium dependent and therefore require basolateral membrane Na-K-ATPase to maintain an efficient transcellular Na gradient for their activity. These transport processes are tightly regulated by various cellular and molecular mechanisms that facilitate their optimal activity during normal physiological processes. Malabsorption of amino acids, recently described in pathophysiological states such as in inflammatory bowel disease (IBD), is undoubtedly responsible for the debilitating symptoms of IBD such as malnutrition, weight loss and ultimately a failure to thrive. Also recently, in vivo models of IBD and in vitro studies have demonstrated that specific immune-inflammatory mediators/pathways regulate specific amino acid transporters. This provides possibilities to derive novel nutrition and immune-based treatment options for conditions such as IBD. © 2020 American Physiological Society. Compr Physiol 10:673-686, 2020.

Enhanced oral bioavailability of vancomycin in rats treated with long-term parenteral nutrition

Long-term parenteral nutrition (PN) can induce intestinal atrophy, leading to a loss of epithelial integrity in the small intestines. This change may alter the intestinal permeability of vancomycin (VCM), a non-absorbable antibiotic. The aim of the present study was to investigate the effect of PN on the pharmacokinetics of VCM in rats. VCM was intravenously (5 mg/kg) or intraduodenally (20 mg/kg) administered to control and PN rats, which were prepared by administration of PN for 9 days. After intravenous administration, there were no significant differences in any of the VCM pharmacokinetic parameters between the control and PN rats. However, after intraduodenal administration, the maximum concentration and area under the plasma concentration-time curve of VCM in PN rats was approximately 2.4- and 2.6-fold higher, respectively, than in the control rats; the calculated bioavailability was approximately 0.5 and 1.3 % in control and PN rats, respectively. These results indicated that PN administration did not affect VCM disposition, but enhanced VCM absorption; however, the enhanced oral VCM bioavailability was statistically, not clinically, significant. Therefore, while long-term PN administration may play a role in the enhancement of VCM bioavailability, this effect may be negligible without any complications.

Regulation of sodium-glutamine cotransport in villus and crypt cells by glucocorticoids during chronic enteritis

BACKGROUND

Assimilation of the preferred nutrient of enterocytes is mediated primarily by sodium (Na)-dependent cotransport (NGct) in the intestine. The predominant NGcT in villus cells, B0AT1, is inhibited secondary to a decrease in cotransporter numbers during chronic intestinal inflammation. In contrast, NGcT mediated by SN2 in crypt cells is stimulated secondary to increased affinity of the cotransporter for glutamine during chronic ileitis. Glucocorticoid is a mainstay of treatment for inflammatory bowel disease. However, its effect on NGcT is not known.

METHODS

The inhibition of B0AT1 in villus cells during chronic intestinal inflammation was reversed back to normal by methylprednisolone (MP). This was secondary to the restoration of the cotransporter numbers in the brush border membrane rather than an alteration in the affinity. The stimulation of NGcT in crypt cells during chronic ileitis was also restored back to its normal levels by MP treatment. This reversal was secondary to the restoration of the altered affinity of the cotransporter SN2 for glutamine.

RESULTS

Kinetic studies and western blot analysis were consistent with functional studies for both cotransporters. Thus, glucocorticoids restore two uniquely altered Na-glutamine cotransporters, B0AT1 in villus and SN2 in crypt cells during chronic enteritis.

CONCLUSIONS

These data indicate that glucocorticoids function as an upstream broad spectrum immune modulator in the chronically inflamed intestine.

Rearing environment affects development of the immune system in neonates

Early-life exposure to appropriate microbial flora drives expansion and development of an efficient immune system. Aberrant development results in increased likelihood of allergic disease or increased susceptibility to infection. Thus, factors affecting microbial colonization may also affect the direction of immune responses in later life. There is a need for a manipulable animal model of environmental influences on the development of microbiota and the immune system during early life. We assessed the effects of rearing under low- (farm, sow) and high-hygiene (isolator, milk formula) conditions on intestinal microbiota and immune development in neonatal piglets, because they can be removed from the mother in the first 24 h for rearing under controlled conditions and, due to placental structure, neither antibody nor antigen is transferred in utero. Microbiota in both groups was similar between 2 and 5 days. However, by 12-28 days, piglets reared on the mother had more diverse flora than siblings reared in isolators. Dendritic cells accumulated in the intestinal mucosa in both groups, but more rapidly in isolator piglets. Importantly, the minority of 2-5-day-old farm piglets whose microbiota resembled that of an older (12-28-day-old) pig also accumulated dendritic cells earlier than the other farm-reared piglets. Consistent with dendritic cell control of T cell function, the effects on T cells occurred at later time-points, and mucosal T cells from high-hygiene, isolator pigs made less interleukin (IL)-4 while systemic T cells made more IL-2. Neonatal piglets may be a valuable model for studies of the effects of interaction between microbiota and immune development on allergy.

Surgery and transplantation - Guidelines on Parenteral Nutrition, Chapter 18

In surgery, indications for artificial nutrition comprise prevention and treatment of catabolism and malnutrition. Thus in general, food intake should not be interrupted postoperatively and the re-establishing of oral (e.g. after anastomosis of the colon and rectum, kidney transplantation) or enteral food intake (e.g. after an anastomosis in the upper gastrointestinal tract, liver transplantation) is recommended within 24 h post surgery. To avoid increased mortality an indication for an immediate postoperatively artificial nutrition (enteral or parenteral nutrition (PN)) also exists in patients with no signs of malnutrition, but who will not receive oral food intake for more than 7 days perioperatively or whose oral food intake does not meet their needs (e.g. less than 60–80%) for more than 14 days. In cases of absolute contraindication for enteral nutrition, there is an indication for total PN (TPN) such as in chronic intestinal obstruction with a relevant passage obstruction e.g. a peritoneal carcinoma. If energy and nutrient requirements cannot be met by oral and enteral intake alone, a combination of enteral and parenteral nutrition is indicated. Delaying surgery for a systematic nutrition therapy (enteral and parenteral) is only indicated if severe malnutrition is present. Preoperative nutrition therapy should preferably be conducted prior to hospital admission to lower the risk of nosocomial infections. The recommendations of early postoperative re-establishing oral feeding, generally apply also to paediatric patients. Standardised operative procedures should be established in order to guarantee an effective nutrition therapy.

Tracking of Green Fluorescent Protein Labeled Escherichia coli Confirms Bacterial Translocation in Blind Loop Rat

BACKGROUND

Previous investigators have documented small intestinal mucosal injury in blind loop rats. However, the definitive evidence of intestinal bacterial translocation in blind loop animals has been lacking. The purpose of this study was to confirm bacterial translocation in blind loop rats and to evaluate the preventive effect of glutamine on bacterial translocation caused by blind loops.

MATERIALS AND METHODS

Escherichia coli TG1 labeled with green fluorescent protein was used to track bacterial translocation by gavage to rats. Six groups (n = 10) of rats were studied: unoperated control rats; rats with self-emptying blind loop; rats with self-filling blind loop; unoperated control rats treated with glutamine, 400 mg/d; rats with self-emptying blind loop treated with glutamine, 400 mg/d; rats with self-filling blind loop treated with glutamine, 400 mg/d. Representative tissue specimens of the mesenteric lymph nodes, liver, spleen, and kidney were aseptically harvested for bacteria culture.

RESULTS

Bacteria were detected in extraintestinal organs of rats with self-emptying blind loop, self-filling blind loop, and self-filling blind loop treated with glutamine. By fluorescence microscope and XbaI restriction digestion analysis, we elucidated that the bacteria isolated from extraintestinal organs were the same bacteria we gavaged to the rats.

CONCLUSION

We confirmed bacterial translocation in self-filling blind loop and self-emptying blind loop rats. In addition, we also showed that glutamine prevents bacterial translocation in self-emptying blind loop rats.

Tolerogenic Protocol for Intestinal Transplantation

Transplantation is standard therapy for many patients suffering from kidney, liver, or heart failure. In contrast, transplantation of the intestine remains a high-risk procedure, which is performed in a minority of patients with short bowel syndrome. The difficulty is the strong alloimmune response caused by intestinal grafts and the complications of the profound immunosuppression. We tested a new clinical immunomodulatory protocol using donor-specific blood transfusion, a strategy that was popular before the introduction of cyclosporine and was recently shown to promote development of regulatory cells. Low-dose steroids and low-dose tacrolimus were administered based on previous observations that tolerance requires an intact immune system, that over-immunosuppression is counterproductive, and that high doses of calcineurin inhibitors block development of regulatory cells whereas low doses promote it. Finally, inflammation within the intestinal graft was minimized to reduce the additional stimulants that the innate immunity of the transplanted intestine exert on the adaptive immune response. Under this protocol, freedom from rejection was achieved in four consecutive intestinal transplant recipients using extremely low immunosuppression.

The effect of glutamine-supplemented total parenteral nutrition on nutrition and intestinal absorptive function in a rat model

The aim of the present study was to evaluate the effect of short-term (7 days) glycyl-glutamine-supplemented total parenteral nutrition (TPN) on nutrition and intestinal absorptive function in a rat model. Thirty Wistar rats, weighting 140-180 g, were divided into three groups (n=10) randomly. The animals received isonitrogenous and isocaloric TPN solutions for 7 days. The nitrogen was supplied by glycyl-glutamine dipeptide-supplemented amino acid solution (group G), and two standard amino acid solutions (group V, group N), respectively. Body weight, plasma glutamine level, nitrogen balance, total tissue water and intestinal absorptive function, assessed by (15-N)-glycine absorption, were investigated. Body weight decreased in three groups at the end of TPN; there was no significant difference in relative body-weight changes. There was a significant improvement of cumulative nitrogen balance and nitrogen retention in group G compared to other groups (P<0.05). There was no significant difference in intestinal glycine absorption (P>0.05) among the three groups. Total tissue water of left thigh muscle was significantly higher in group V and group N than that in group G (P<0.05). The results indicated that short-term (7 days) TPN supplemented with glycyl-glutamine improved plasma glutamine level and nitrogen balance, decreased water content of muscle, but had no beneficial effect on absorptive function in a rat model.

Ochratoxin A increases permeability through tight junctions by removal of specific claudin isoforms

On interaction with the intestine, the mycotoxin ochratoxin A is know to cause rapid inflammation, diarrhea, and increased bacterial translocation. All these effects are consistent with a decrease in epithelial barrier function. However, this has not been shown directly. We determined that ochratoxin A is able to reduce the barrier properties of the model intestinal cell line Caco-2. Over 24 h, ochratoxin A reduces the transepithelial electrical resistance of Caco-2 monolayers growing on Transwell filters by ∼40%. At the same time, the permeability of the monolayer is increased with respect to 4- and 10-kDa FITC dextrans, but not to 20- or 40-kDa dextrans. Immunoblotting and immuofluorescence reveal that the decrease in barrier properties is concomitant with disappearance of claudins 3 and 4, but not claudin 1 from Caco-2 cell membranes. These results suggest that ochratoxin A is able to modulate the barrier function of Caco-2 cells by removal of specific claudin isoforms.

Randomized, double-blind, controlled study of glycyl-glutamine-dipeptide in the parenteral nutrition of patients with acute leukemia undergoing intensive chemotherapy

OBJECTIVE

Glutamine has stimulatory effects on lymphocytes and mucosa cells in vitro and, when given with parenteral nutrition, has been shown to improve the clinical course of patients after bone marrow transplantation and in the critically ill. This study investigated the clinical and immunologic effects of parenteral glycyl-glutamine supplementation in patients with acute leukemia receiving intensive conventional chemotherapy without bone marrow transplantation.

METHODS

A randomized, double-blind, controlled study compared a standard glutamine-free parenteral nutrition with a glycyl-glutamine-supplemented parenteral nutrition (Glamin, Baxter, Erlangen, Germany) containing 20 g of glutamine in adult patients with acute myeloid leukemia undergoing myelosuppressive chemotherapy. Clinical end points included the duration of neutropenia and the incidence and duration of neutropenic fever. To analyze the effects of glutamine on immunocompetent cells, CD4+ and CD8+ T cells and HLA-DR expression on monocytes were assessed by flow cytometry throughout the treatment course.

RESULTS

Fifty-four adult patients entered the study and were randomized. In 45 of 127 chemotherapy cycles, parenteral nutrition was given, and 40 cycles (20 with and 20 without glutamine) were evaluated for comparison. The median durations of neutropenia were 18 d (range, 9-29 d) in the glutamine group and 22.5 d (range, 13-48 d) in the control group (P = 0.052), whereas the median durations of neutropenic fever were 5.5 d (range, 0-13 d) and 5 d (range, 0-31 d), respectively (P = 0.74). Using Kaplan-Meier analysis and controlling for the type of chemotherapy, we found a significantly faster neutrophil recovery in patients receiving glutamine than in the control group (P = 0.040) in patients receiving a high-dose cytarabine regimen. There was no significant difference in the recovery of CD4+ or CD8+ lymphocytes or monocyte activation between groups.

CONCLUSION

In patients with acute myeloid leukemia requiring parenteral nutrition, glycyl-glutamine supplementation could hasten neutrophil recovery after intensive myelosuppressive chemotherapy. However, no impact of glutamine on neutropenic fever or other criteria of immunologic recovery was detected.

Glycyl-glutamine-supplemented long-term total parenteral nutrition selectively improves structure and function in heterotopic small-bowel autotransplantation in the pig

Marked atrophy and impaired absorptive and barrier function occur in transplanted small intestinal graft during total parenteral nutrition (TPN), TPN is required by all the patients after small bowel transplantation (SBT). Glutamine (Gln) is a conditional indispensable amino acid that is not included in regimens for parenteral nutrition because of its chemical instability in aqueous solution. Glutamine-containing dipeptide, however, is heat-stable. With this study, we determine whether the glycyl-glutamine-supplemented long-term TPN improves mucosal structure and function in heterotopic transplanted small intestinal graft in the pig. Ten outbred pigs, randomly divided into two groups, underwent heterotopic small bowel autotransplantation. In the STPN group, the animals received standard TPN without glycyl-glutamine (Gly-Gln) and in the GTPN group, the animals received isonitrogenous (0.3g kg day(-1)) and isocalories (nonprotein calories, 30 kcal kg day(-1)) TPN with Gly-Gln (3% Gln) for 28 days. At the end of TPN, there was no significant difference in the body weight loss between two groups ( P>0.05). The mucosal contents of Gln and protein were significantly higher in the GTPN group than in the STPN group ( P<0.05). The mucosal disaccharidase activities in the homogenate of the graft mucosa of the GTPN group were significantly higher than that of the STPN group ( P<0.05). The villous height, surface area, mucosal thickness were significantly higher in the GTPN group than in the STPN group ( P<0.05). There was no significant difference in crypt depth between the two groups ( P>0.05). These results suggest that glycyl-glutamine-supplemented long-term TPN improves graft mucosal structure in heterotopic autotransplanted small bowel grafts in the pig. Long-term (4 weeks) TPN supplemented with Gln could alleviate small intestinal graft atrophy, but could not completely eliminate atrophy.

Glutamine preserves protein synthesis and paracellular permeability in Caco-2 cells submitted to "luminal fasting"

This study used polarized cell line Caco-2 as a model of human enterocytes to determine: 1) whether deprivation of nutrients on the apical (luminal) side of the epithelium (fasting) alters protein synthesis in enterocytes; 2) if so, whether glutamine can attenuate the effects of fasting; and 3) whether the effects of glutamine depend on its route (i.e., apical vs. basolateral) of supply. Caco-2 cells were submitted to nutrient deprivation on the apical side to mimic the effects of fasting, whereas the basolateral side of the epithelium remained exposed to regular medium. Cells were then incubated with [2H3]leucine with or without glutamine, and the fractional synthesis rate (FSR) of total cell protein was determined from [2H3]leucine enrichments in protein-bound and intracellular free leucine measured by gas chromatography/mass spectrometry. A 24-h apical nutrient deprivation (luminal fasting) was associated with a decline in intracellular glutamine, glutamate, and glutathione concentrations (-38, -40, and -40%, respectively), protein FSR (-20%), and a rise in passage of dextran, an index of transepithelial permeability. In fasted cells, basolateral or luminal glutamine supplementation did not alter the glutathione pool, but it restored protein FSR and improved permeability. The effects of glutamine were abolished by 6-diazo-oxo-l-norleucine, an inhibitor of glutaminase, and was mimicked by glutamate. We conclude that in Caco-2 cells, protein synthesis depends on nutrient supply on the apical side, and glutamine regardless of the route of supply corrects some of the deleterious effects of fasting in a model of human enterocytes through its deamidation into glutamate.

Relationship between overexpression of NK-1R, NK-2R and intestinal mucosal damage in acute necrotizing pancreatitis

AIM: To study the expression of neurokinin-1 receptor (NK-1R) and neurokinin-2 receptor (NK-2R) in distal ileum of acute necrotizing pancreatitis (ANP) and to evaluate the relationship between expression of these two receptors and intestinal mucosal damage.

METHODS: A total of 130 adult Sprague-Dawley rats were randomly divided into two groups: the rats in ANP group (n = 80) were induced by the retrograde intraductal infusion of 30 g·L^-1 sodium taurocholate. And the rats in normal control group (n = 50) received laparotomy only. Sacrifices were made 6 h, 12 h, 24 h and 48 h later in ANP and normal control group after induction respectively. Intestinal mucosal permeability was studied by intrajejunal injection of 1.5mCi radioactive isotope ^99mTc-diethlene triamine pentacetic acid (DTPA) and the radioactivity of ^99mTc-DTPA content in urine was measured 6 h, 12 h, 24 h and 48 h after induction. Then the pancreas and intestine were prepared for pathology. Reverse transcription polymerase chain reaction (RT-PCR) was used to determine the mRNA expression of NK-1R and NK-2R, and Western blot was used to investigate the protein level of NK-1R and NK-2R.

RESULTS: In ANP rats, serious histologic damages in intestinal mucosa were observed, and the radioactivity of ^99mTc-DTPA in urine increased significantly in the ANP group. RT-PCR revealed that NK-1R and NK-2R mRNA level was overexpressed in the distal ileum of ANP as compared with the normal control group. Western blot discovered stronger NK-1R (14-fold increase) and NK-2R (9-fold increase) immunoreactivity in the intestinal mucosa of ANP rats. Moreover, the overexpression of NK-1R was associated with mucosal pathological score (r = 0.77, P < 0.01) and intestinal permeability (r = 0.68, P < 0.01) in ANP rats.

CONCLUSION: NK-1R and NK-2R contribute to disrupted neuropeptides loop balance, deteriorate intestinal damage, and are involved in pathophysiological changes in ANP.

Effects of recombinant human growth hormone on rat septic shock with intraabdominal infection by E. coli

AIM: To investigate the therapeutic effects of recombinant human growth hormone (rhGH) on rat septic shock with intraabdominal infection by E. coli and its possible mechanism.

METHODS: 76 SD rats were divided into 3 groups randomly: control group (group C, n = 16) without any special treatment, septic shock group (group S, n = 30) received bolus injection of E.coli (1 × 10¹⁰ cfu·L^-1,15 mL·kg^-1, ip), treated group (group T, n = 30) received bolus injection of E.coli, and then followed by rhGH injection (2.25 U·kg^-1·d^-1, im). Group S and group T were further divided into 1d and 3d subgroups, respectively (n = 15 each). Mean arterial pressure (MAP), levels of plasma TNFα and endotoxin and leukocyte count were determined on 1st day and 3rd day after E.coli injection. Another 39 SD rats were divided into groups C, S and T (n = 13 each) just for observing survival rate within 1 week.

RESULTS: (1) On 1st and 3rd day, MAP in group S decreased markedly, and MAP on 1st day lowered more than that of 3rd day (P < 0.01), while MAP in group T just decreased slightly. The survival rate within 1 week was much higher in group T (84.6%) than in group S (46.2%) (P < 0.01). (2)On 1st day, plasma TNFα and endotoxin elevated significantly in group S and group T (P < 0.05), and endotoxin in group S had more increase (P < 0.01). On 3rd day, TNFα in group S returned to the level of group C (P > 0.05),while TNFα in group T went down below the level of group C(P < 0.01). On 3rd day, endotoxin in group S declined, but was still higher than that of group C (P < 0.01), endotoxin in group T returned to the level of group C (P > 0.05). (3) On 1st day, neutrophil ratio in total leukocyte count in both group S and group T increased significantly (P < 0.05 vs group C).

CONCLUSION: rhGH showed beneficial effects on rat septic shock. The possible mechanisms may involve the attenuation of bacteria/endotoxin translocation and decreased systemic endotoxin level; inhibition of the production and release of TNFα; improved circulatory function; improved systemic host defenses and maintenance of intestinal mucosa barrier.

Effects of intrauterine growth restriction and intraamniotic insulin-like growth factor-I treatment on blood and amniotic fluid concentrations and on fetal gut uptake of amino acids in late-gestation ovine fetuses

OBJECTIVES

To investigate, in the late-gestation ovine fetus: 1) amino acid concentrations in blood and amniotic fluid, 2) the effects of intrauterine growth restriction (IUGR) induced by placental embolization on these concentrations, 3) fetal gut uptake of glutamine in healthy and IUGR fetuses, and 4) the effects of intraamniotic insulin-like growth factor-I (IGF-1) treatment on these parameters.

METHODS

Fetuses were randomly assigned to control (n = 9), IUGR + saline (n = 9), or IUGR + IGF-1 (n = 11) groups. IUGR was induced by uteroplacental embolization from 114 to 119 days (term = 145 days). IUGR fetuses received daily intraamniotic injections of saline or IGF-1 (20 microg/d) from 120 to 130 days.

RESULTS

Baseline amino acid concentration was higher in fetal blood than amniotic fluid for all essential amino acids except lysine and histidine, but was lower for serine, alanine, and methylhistidine. Embolization reduced total amino acid concentration in blood and amniotic fluid by approximately 15%. Concentrations were reduced for serine, glutamine, and methylhistidine in blood and for serine in amniotic fluid, but were increased for glycine, alanine, and asparagine in blood and for alanine in amniotic fluid. Glutamine was taken up by the fetal gut (glutamine:oxygen quotient of 0.65) and citrulline was released by the gut. IGF-1 treatment did not alter amino acid concentration in blood or amniotic fluid, but reduced gut uptake of glutamine from blood and the gut glutamine:oxygen quotient by 15%. Citrulline release was unchanged.

CONCLUSIONS

These data suggest that amniotic fluid amino acids are not simply filtered from fetal blood and may provide an important pool of nutrients for the fetus. They demonstrate for the first time that glutamine is taken up by the fetal gut. IGF-1 treatment may promote gut utilization of amino acids from the amniotic fluid pool.

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 oral supplement of L-glutamine on diverted colon wall

Diverted colorectal segments can present trophic and inflammatory changes. These alterations are of special importance in the patients whose colostomy becomes permanent, as well as in the differential diagnosis with other inflammatory diseases. This study was accomplished to quantify these alterations and to determine if oral supplement of L-glutamine would avoid them. Twenty-six adult male Wistar rats were distributed in three groups: control, colostomized and colostomized+L-glutamine. The colostomized group received a loop colostomy. The colostomized+L-glutamine group received a colostomy similar to the previous group and oral supplement of L-glutamine. Partial volumes of all layers of the colonic wall were measured by image analysis stereology. The diversion caused a decrease of partial volumes of the mucosa and the epithelium as well, and also of the height of the intestinal crypts (p<0.05). There was an increase of partial volumes of the lamina propria, of the submucosa and of the muscularis mucosae vs controls (p<0.05). The partial volume of the muscularis propria didn't show significant alteration. The supplementation of L-glutamine was effective in preventing the atrophy of mucosa and epithelium (p<0.05), also avoiding the increase of partial volumes of the submucosa and lamina propria (p<0.05). This supplement didn't change significantly the muscular layers. In conclusion, colostomy causes the atrophy of the colon wall, mainly due to the atrophy of the epithelium. The supplementation of L-glutamine is able to avoid these changes.

Bacterial translocation in clinical intestinal transplantation

BACKGROUND

Bacterial translocation (BT) has been suggested to be responsible for the high incidence of infections occurring after small bowel transplantation (SBTx). Bacterial overgrowth, alteration of the mucosal barrier function as a consequence of preservation injury or acute rejection (AR), and potent immunosuppression are all associated with BT. The aim of this study was to evaluate and quantify the correlation of BT with these events.

METHODS

Fifty pediatric SBTx recipients on tacrolimus and prednisone immunosuppression were analyzed. Blood, stool, and liver biopsies and peritoneal fluid were cultured (circa 4000 total specimens) when infection was clinically suspected or as part of follow-up. BT episodes were considered when microorganisms were found simultaneously in blood or liver biopsy and stool.

RESULTS

BT (average of 2.0 episodes/patient) was evident in 44% of patients and was most frequently caused by Enterococcus, Staphylococcus, Enterobacter, and Klebsiella. The presence of a colon allograft was associated with a higher rate of BT (75% vs. 33.3%). Furthermore, the transplantation procedure (colon vs. no colon) affected the rate of BT: SBTx=40% vs. 25%, combined liver and SBTx=100% vs. 30%, multivisceral transplantation=25% vs. 50%. AR was associated with 39% of BT episodes. BT followed AR in 9.6% of the cases. In 5.2% of the cases, positive blood cultures without stool confirmation of the bacteria were seen. Prolonged cold ischemia time (CIT) affected BT rate significantly (CIT>9 hr 76% vs. CIT<9 hr 20.8%).

CONCLUSIONS

This study shows that 1) a substantial percentage of, but not all, BT is associated with AR, 2) the presence of a colon allograft increases the risk for BT, and 3) a long CIT is associated with a high incidence of BT after SBTx.

Glutamine and the gastrointestinal tract

The amino acid glutamine has become one of the most intensively studied nutrients in the field of nutrition and metabolic support. A variety of studies in cell culture systems, animal models of gut mucosal atrophy, injury/repair and adaptation and a limited number of clinical trials demonstrate trophic and cytoprotective effects of glutamine in small bowel and colonic mucosal cells. Although the routine clinical use of glutamine-enriched parenteral and enteral nutrient solutions remains controversial, available data demonstrate both the safety and metabolic and clinical efficacy of glutamine treatment in selected patient groups. Basic investigations are elucidating underlying mechanisms of glutamine action in intestinal cells. These will inform preclinical and clinical investigations designed to determine glutamine efficacy in selected gastrointestinal disorders. Emerging clinical trials will further define the utility of adjunctive glutamine supplementation as a component of specialized nutrition support in gastrointestinal disease.

Gastrointestinal transplantation: An update

Gastrointestinal transplantation is a life-saving option for patients who have chronic intestinal failure and cannot tolerate total parenteral nutrition (TPN). Early referral is important because of the scarcity of donors and the increased risk of complications in debilitated recipients. One-year patient survival rates range from 50% to 70%. Despite the use of intense immune suppression, most patients experience at least 1 episode of graft rejection. More than 80% of the survivors are able to stop TPN and resume an unrestricted oral diet. Patients with functioning grafts have a good quality of life.

Total parenteral nutrition and cholestasis

Hepatobiliary dysfunction is recognized as a major adverse effect of total parenteral nutrition (TPN). It is unknown if this is caused by a deficiency or toxicity of the TPN solution or the underlying pathophysiology of disease processes that require TPN therapy. This article presents algorithms for evaluating abnormal liver tests in patients on TPN and discusses treatment options and the current status of intestinal transplantation.