Effect of glutamine-supplemented total parenteral nutrition on the small bowel of septic rats

A Systems Vaccinology Approach Reveals the Mechanisms of Immunogenic Responses to Hantavax Vaccination in Humans

Hantavax is an inactivated vaccine for hemorrhagic fever with renal syndrome (HFRS). The immunogenic responses have not been elucidated yet. Here we conducted a cohort study in which 20 healthy subjects were administered four doses of Hantavax during 13-months period. Pre- and post- vaccinated peripheral blood mononuclear cells (PBMCs) and sera were analysed by transcriptomic and metabolomic profilings, respectively. Based on neutralizing antibody titers, subjects were subsequently classified into three groups; non responders (NRs), low responders (LRs) and high responders (HRs). Post vaccination differentially expressed genes (DEGs) associated with innate immunity and cytokine pathways were highly upregulated. DEG analysis revealed a significant induction of CD69 expression in the HRs. High resolution metabolomics (HRM) analysis showed that correlated to the antibody response, cholesteryl nitrolinoleate, octanoyl-carnitine, tyrosine, ubiquinone-9, and benzoate were significantly elevated in HRs, while chenodeoxycholic acid and methyl palmitate were upregulated in NRs and LRs, compared with HRs. Additionally, gene-metabolite interaction revealed upregulated gene-metabolite couplings in, folate biosynthesis, nicotinate and nicotinamide, arachidonic acid, thiamine and pyrimidine metabolism in a dose dependent manner in HR group. Collectively, our data provide new insight into the underlying mechanisms of the Hantavax-mediated immunogenicity in humans.

REducing Deaths due to OXidative Stress (The REDOXS Study): Rationale and study design for a randomized trial of glutamine and antioxidant supplementation in critically-ill patients

Critically-ill patients experience an extent of hyperinflammation, cellular immune dysfunction, oxidative stress and mitochondrial dysfunction. Supplementation with key nutrients, such as glutamine and antioxidants, is most likely to have a favourable effect on these physiological derangements, leading to an improvement in clinical outcomes. The results of two meta-analyses suggest that glutamine and antioxidants may be associated with improved survival. The purpose of the present paper is to report the background rationale and study protocol for the evaluation of the effect of high-dose glutamine and antioxidant supplementation on mortality in a large-scale randomized trial in 1200 mechanically-ventilated, critically-ill patients. Patients admitted to an intensive care unit (ICU) with clinical evidence of severe organ dysfunction will be randomized to one of four treatments in a 2 x 2 factorial design: (1) glutamine; (2) antioxidant therapy; (3) glutamine and antioxidant therapy; (4) placebo. The primary outcome for this study is 28 d mortality. The secondary outcomes are duration of stay in ICU, adjudicated diagnosis of infection, multiple organ dysfunction, duration of mechanical ventilation, length of stay in hospital and health-related quality of life at 3 and 6 months. A novel design feature is the combined use of parenteral and enteral study nutrients dissociated from the nutrition support. The therapeutic strategies tested in the randomized trial may lead to less morbidity and improved survival in critically-ill patients. The trial will be conducted in approximately twenty tertiary-care ICU in Canada and the first results are expected in 2009.

Glutamine supplementation in serious illness: a systematic review of the evidence

OBJECTIVE

To examine the relationship between glutamine supplementation and hospital length of stay, complication rates, and mortality in patients undergoing surgery and experiencing critical illness.

DATA SOURCES

Computerized search of electronic databases and search of personal files, abstract proceedings, relevant journals, and review of reference lists.

STUDY SELECTION

We reviewed 550 titles, abstracts, and articles. Primary studies were included if they were randomized trials of critically ill or surgical patients that evaluated the effect of glutamine vs. standard care on clinical outcomes. DATA EXTRACTION We abstracted relevant data on the methodology and outcomes of primary studies in duplicate, independently. DATA SYNTHESIS There were 14 randomized trials comparing the use of glutamine supplementation in surgical and critically ill patients. When the results of these trials were aggregated, with respect to mortality, glutamine supplementation was associated with a risk ratio (RR) of 0.78 (95% confidence interval [CI], 0.58-1.04). Glutamine supplementation was also associated with a lower rate of infectious complications (RR, 0.81; 95% CI, 0.64-1.00) and a shorter hospital stay (-2.6 days; 95% CI, -4.5 to -0.7). We examined several -specified subgroups. Although there were no statistically significant subgroup differences detected, there were some important trends. With respect to mortality, the treatment benefit was observed in studies of parenteral glutamine (RR, 0.71; 95% CI, 0.51-0.99) and high-dose glutamine (RR, 0.73; 95% CI, 0.53-1.00) compared with studies of enteral glutamine (RR, 1.08; 95% CI, 0.57-2.01) and low-dose glutamine (RR, 1.02; 95% CI, 0.52-2.00). With respect to hospital length of stay, all of the treatment benefit was observed in surgical patients (-3.5 days; 95% CI, -5.3 to -1.7) compared with critically ill patients (0.9 days; 95% CI, -4.9 to 6.8).

CONCLUSION

In surgical patients, glutamine supplementation may be associated with a reduction in infectious complication rates and shorter hospital stay without any adverse effect on mortality. In critically ill patients, glutamine supplementation may be associated with a reduction in complication and mortality rates. The greatest benefit was observed in patients receiving high-dose, parenteral glutamine.

Glutamine for the gut: mystical properties or an ordinary amino acid?

Glutamine is a nonessential amino acid that can be synthesized from glutamate and glutamic acid by glutamine synthetase. It is the preferred fuel for the small intestine in the rat. Results from animal studies suggest that both glutamine-supplemented parenteral nutrition and enteral diets may prevent bacterial translocation. This effect may be modulated through the preservation and augmentation of small bowel villus morphology, intestinal permeability, and intestinal immune function. The existing data from studies with humans are less compelling. What, if any, intestinal deficits actually occur during provision of exclusive parenteral nutrition remains unclear. Furthermore, the clinical significance of these changes is largely undefined. Nevertheless, glutamine and glutamine supplementation appear to be important for the normal maintenance of intestinal morphology and function, intestinal adaptation following resection, and prevention of clinical infection related to bacterial translocation. The existing data on the use of parenteral and enteral glutamine for preservation of intestinal morphology and function and prevention of bacterial translocation in humans are reviewed in this article. Pertinent animal data are also described.

Glutamine reduces phorbol-12,13-dibutyrate-induced macromolecular hyperpermeability in HT-29Cl.19A intestinal cells

BACKGROUND

Loss of mucosal integrity is associated with intestinal hyperpermeability, which may be inhibited by glutamine. The nature of this effect is unknown. The effect of glutamine on protein kinase C (PKC)-mediated hyperpermeability in HT-29Cl.19A intestinal cells was studied.

METHODS

Confluent monolayers of HT-29C1.19A cells were cultured on permeable filters and mounted in Ussing chambers for permeability studies. Apical to basolateral transepithelial permeability for intact horseradish peroxidase (HRP) was determined. Phorbol-12,13-dibutyrate (PDB) was used to activate PKC-mediated hyperpermeability, and the effect of glutamine (0.6 mmol/L) was studied.

RESULTS

Two hours of PDB stimulation increased the HRP flux, reaching five times control values after 4 hours. Bilateral exposure to glutamine for 4 hours reduced PDB-induced hyperpermeability (37%). Preincubation with glutamine 2 hours before PDB stimulation showed an earlier and greater effect (3 hours, 43%; 4 hours, 50%). This bilateral effect of glutamine was mimicked by separate apical exposure. Basolateral exposure alone had no effect.

CONCLUSIONS

Glutamine rapidly reduced the PKC-mediated hyperpermeability for HRP in HT-29Cl.19A intestinal cells. The dependency on apical exposure suggests that glutamine may be more effective when delivered by the enteral route.

Alanylglutamine-enriched total parenteral nutrition improves protein metabolism more than branched chain amino acid-enriched total parenteral nutrition in protracted peritonitis

Branched chain amino acids (BCAAs) and glutamine are both recommended in catabolic states. The object of this study was to compare the efficacies of alanylglutamine (Ala-Gln)-enriched and BCAA-enriched total parenteral nutrition (TPN) on the protein kinetics in peritonitis. Rats were divided into Ala-Gln and BCAA groups after intraperitoneal implantation of an osmotic pump, delivering a continuous infusion of Escherichia coli. Glutamine composed 30.0% (w/v) of the total amino acids in the Ala-Gln group, and BCAA composed 30.5% (w/v) of the total amino acids in the BCAA group. The two solutions were isocaloric and isonitrogenous. Whole body protein turnover and organ fractional protein synthetic rates (FSR) were measured on days 3 and 5. Serum amino acid levels and mucosal morphology were determined. Ala-Gln group had higher rates of whole body protein turnover, and hepatic FSR on both days. Serum glutamine levels correlated with hepatic and muscle FSR. Ala-Gln TPN group had greater mucosal thickness, numbers of mitoses per crypt, and FSR in distal intestine. Ala-Gln-enriched TPN may be a useful nutritional treatment modality in sepsis.

Alanyl-glutamine-supplemented total parenteral nutrition improves survival and protein metabolism in rat protracted bacterial peritonitis model

BACKGROUND

The effects of glutamine-enriched total parenteral nutrition (TPN) solution on survival, and protein turnover in the whole body and in individual organs were investigated in a rat protracted peritonitis model.

METHODS

Twenty-three rats underwent venous catheter insertion. Osmotic pumps were implanted in the peritoneal cavity to allow continuous delivery of Escherichia coli (4 x 10(8) CFU/d). The conventional TPN group received a conventional amino acid solution. The Ala-Gln TPN group received an alanyl-glutamine-enriched TPN solution. The two TPN solutions were isocaloric and isonitrogenous.

RESULTS

Over the 5 days of TPN treatment, the survival rate of the Ala-Gln group was significantly higher than that of the conventional group. The Ala-Gln group tended to have increased whole-body protein turnover compared with the conventional group. Fractional protein synthetic rates (FSR) in the liver and gastrocnemius muscle of the Ala-Gln group were significantly higher than those of the conventional group. The serum glutamine concentration correlated positively with the FSR of both liver and muscle. The Ala-Gln group showed significantly greater mucosal height and mitoses per crypt, in the small intestine, than did the conventional group.

CONCLUSIONS

Our results suggested that, in comparison with standard glutamine-free TPN, Ala-Gln-supplemented TPN increases protein synthesis in the liver and skeletal muscle, protects the morphology of the intestinal mucosa, and improves survival in protracted bacterial peritonitis. Ala-Gln supplementation may be useful in septic patients.

Glutamine: is it a conditionally required nutrient for the human gastrointestinal system?

Glutamine is a nonessential amino acid which can be synthesized from glutamate and glutamic acid by glutamine synthetase. It is the preferred fuel for the rat small intestine. Animal studies have suggested both glutamine-supplemented parenteral nutrition and enteral diets may prevent bacterial translocation. This effect is thought to be modulated via the preservation and augmentation of small bowel villus morphology, intestinal permeability and intestinal immune function. The existing data are less compelling in humans. It remains unclear what, if any, intestinal deficits actually occur in humans during provision of exclusive parental nutrition. Furthermore, the clinical significance of these changes is largely undefined in humans. The existing data on the use of parenteral and enteral glutamine for the purpose of preserving intestinal morphology and function, and the prevention of bacterial translocation in humans are reviewed. Pertinent animal data are also described.

The role of glutamine, short-chain fatty acids, and nucleotides in intestinal adaptation to gastrointestinal disease

Important first steps have been taken towards establishing how some nutrients interact with genes and affect intestinal adaptation. These mechanisms may be typical of how other nutrients influence cell function and turnover and help to maintain intestinal integrity. The dietary effects of nucleotides on intestinal cell mucosa act at the gene transcription level. The dietary effects of nucleotides on immune suppression also may act through similar mechanisms. The effects of the other trophic agents may interact at this level or at other levels. Scientific interest in how the various tropic factors work to maintain and repair the gastrointestinal tract is manifested by a growing body of research that demonstrates potential mechanisms for nutrient-gene interaction and how much interactions affect intestinal development and turnover. It seems clear that intestinal gene transcription and the activity of transcription factors are at least sometimes directly related to nutrition. The techniques of molecular biology now permit the exploration and explanation of how dietary factors, such as glutamine, SCFAs, and nucleotides, affect normal and pathologic intestinal mucosal development, function, adaptation, and repair.

Glutamine dipeptide-supplemented parenteral nutrition maintains intestinal function in the critically ill

BACKGROUND/AIMS

Long-term total parenteral nutrition is accompanied with mucosal atrophy and subsequent malabsorption syndrome. Current information attests the important role of glutamine in maintaining intestinal structure and function. The aim of this study was to investigate the effect of glutamine dipeptide supplementation on small intestinal absorption capacity during critical illness.

METHODS

Twelve intensive care unit patients were uniformly randomized to receive isonitrogenous (0.26 g nitrogen.kg-1.day-1) and isoenergetic (155 kJ.kg-1.day-1) parenteral nutrition over 9 days. The control group received a conventional amino acid solution (1.5 g amino acids.kg-1.day-1), and the test group received a complete amino acid solution containing the dipeptide L-alanyl-L-glutamine (20 g/L). On days 8 and 9, a modified D-xylose test was performed.

RESULTS

Excretion of D-xylose during the 5-hour test period was 7.4 +/- 1.1 g (test) vs. 3.8 +/- 0.9 g (control) (P < 0.05). The 2-hour serum D-xylose concentration was 38.7 +/- 3.0 (test) vs. 27.8 +/- 2.9 mg/100 mL (control) (P < 0.05). Kinetic evaluation showed higher maximum D-xylose blood concentration and higher values for the area under the curve with the peptide.

CONCLUSIONS

The results strongly suggest that glutamine dipeptide-containing total parenteral nutrition prevents intestinal atrophy and increased permeability associated with glutamine-free parenteral nutrition.

Effect of free glutamine and alanyl-glutamine dipeptide on mucosal proliferation of the human ileum and colon

BACKGROUND/AIMS

Glutamine (Gln) is considered a trophic factor for small intestinal epithelia, which is important during severe illness. Its use in parenteral nutrition is precluded by its instability, a problem that may be overcome by use of the stable dipeptide L-alanyl-L-glutamine (Ala-Gln). The hypothesis was tested that Gln or Ala-Gln may stimulate cell proliferation not only in the ileum but also in the proximal and distal colon and, thus, may contribute to the gut barrier function.

METHODS

Biopsy samples from the normal human ileum, proximal colon, and rectosigmoid were incubated for 4 hours with Gln (2 mmol/L), Ala-Gln (2 mmol/L), and saline (control). Cells in S phase were labeled with bromodeoxyuridine. In longitudinal crypt sections labeled and quiescent cells were counted.

RESULTS

Gln as well as Ala-Gln stimulated crypt cell proliferation in the ileum, proximal colon, and rectosigmoid colon. In ileal specimens, labeling was greater in the entire crypt, whereas in both colonic regions, the trophic effect was confined to the basal crypt compartments.

CONCLUSIONS

Gln and Ala-Gln have trophic effects not only in the ileum, but also in the proximal and distal colon. This could be important during parenteral nutrition when mucosal atrophy may weaken the gut barrier.