Glutamine-supplemented total parenteral nutrition improves immunological status in anorectic patients

Gut microbiome-brain interactions in anorexia nervosa: Potential mechanisms and regulatory strategies

Anorexia nervosa (AN) is a psychiatric disorder characterised by malnutrition, fear of weight gain, and body image disturbances. The aetiology of AN is complex, and may involve environmental factors, genetic factors, and biochemical factors, with the latter meaning that AN may be closely associated with neurons, neurotransmitters, and hormones related to appetite and emotional regulation. In addition, an increasing number of studies have shown there is a link between the intestinal microbiota and psychiatric disorders, such as depression. However, few studies and reviews have focused on AN and gut microbes. Accordingly, in this review, we examine the potential pathogenesis of AN in terms of changes in the gut microbiota and its metabolites, and their effects on AN. The neurobiological function of the nervous system in relation to AN are also been mentioned. Furthermore, we suggest future research directions for this field, and note that probiotics may be developed for use as dietary supplements to help alleviate AN in patients.

Obesity increases hepatic glycine dehydrogenase and aminomethyltransferase expression while dietary glycine supplementation reduces white adipose tissue in Zucker diabetic fatty rats

Obesity is associated with altered glycine metabolism in humans. This study investigated the mechanisms regulating glycine metabolism in obese rats. Eight-week-old Zucker diabetic fatty rats (ZDF; a type-II diabetic animal model) received either 1% glycine or 1.19% L-alanine (isonitrogenous control) in drinking water for 6 weeks. An additional group of lean Zucker rats also received 1.19% L-alanine as a lean control. Glycine concentrations in serum and liver were markedly lower in obese versus lean rats. Enteral glycine supplementation restored both serum and hepatic glycine levels, while reducing mesenteric and internal white fat mass compared with alanine-treated ZDF rats. Blood glucose and non-esterified fatty acid (NEFA) concentrations did not differ between the control and glycine-supplemented ZDF rats (P > 0.10). Both mRNA and protein expression of aminomethyltransferase (AMT) and glycine dehydrogenase, decarboxylating (GLDC) were increased in the livers of obese versus lean rats (P < 0.05). In contrast, glycine cleavage system H (GCSH) hepatic mRNA expression was downregulated in obese versus lean rats, although there was no change in protein expression. These findings indicate that reduced quantities of glycine observed in obese subjects likely results from an upregulation of the hepatic glycine cleavage system and that dietary glycine supplementation potentially reduces obesity in ZDF rats.

Distinct Effects of Growth Hormone and Glutamine on Activation of Intestinal Stem Cells

BACKGROUND

For patients with short bowel syndrome under parenteral nutrition support, growth hormone (GH) and glutamine (GLN) have been found to help the growth of intestinal mucosa. In this research, we studied the effects of GH and GLN on intestinal stem cells (ISCs).

METHODS

The in vitro and in vivo effects of GH and/or GLN on ISCs were evaluated by observing the ability of ISCs to form organoids in a Matrigel culture system. The expression levels of stemness and differentiation markers in ISCs and organoids were assessed using quantitative real-time polymerase chain reaction, immunofluorescence assay, and immunohistochemistry staining.

RESULTS

In vitro administration of GH activated the stemness of ISCs, whereas GLN enhanced the expression of chromogranin A and Muc2, which are differentiation markers in enteroendocrine and goblet cells, respectively. Administration of GH or GLN in mice showed that GH, but not GLN, upregulated the proliferative activity of ISCs with increased formation of crypt organoids. In addition, GH increased the expression of Lgr5 and GLN enhanced expression of Muc2 in the crypt fractions of the intestines in mice.

CONCLUSION

These results suggest that GH mainly enhances proliferative activities, whereas GLN promotes the differentiation potential of ISCs.

Immune disorders in anorexia

Anorexia nervosa is a disease involving eating disorders. It mainly affects young people, especially teenage women. The disease is often latent and occurs in many sub-clinical and partial forms. Approximately from 0.3% to 1% of the population suffers from anorexia. It has been shown that patients with anorexia develop neurotransmitter-related disorders, leading to uncontrolled changes in the immune and endocrine systems. Interactions between cytokines, neuropeptides, and neurotransmitters play an important role in disease development. Significant malnutrition induces disorders and alterations in T-cell populations. The cellular response in patients with anorexia nervosa has been shown to be normal, although opinions on this issue are controversial. Laboratory studies on neutrophils in anorexia patients showed decreased adhesion and reduced bactericidal and cell activities. Despite such unfavourable results, patients with anorexia are resistant to infections, which are very rare in this group. Glutamine improves the performance of the human immune system. The administration of glutamine to anorexia patients, as a supplement to parenteral nutrition, has resulted in significant improvements in immune system parameters. The results of previous studies on the causes and risk factors in the development of anorexia nervosa are still ambiguous. One can hope that the differences and similarities between patients with anorexia nervosa and those with other forms of protein-calorie malnutrition may be helpful in determining the relationship between nutritional status and body defences and susceptibility to infection, and can help to broaden the knowledge about the aetiopathogenesis of anorexia nervosa.

Dietary L-glutamine supplementation modulates microbial community and activates innate immunity in the mouse intestine

This study was conducted to determine effects of dietary supplementation with 1 % L-glutamine for 14 days on the abundance of intestinal bacteria and the activation of intestinal innate immunity in mice. The measured variables included (1) the abundance of Bacteroidetes, Firmicutes, Lactobacillus, Streptococcus and Bifidobacterium in the lumen of the small intestine; (2) the expression of toll-like receptors (TLRs), pro-inflammatory cytokines, and antibacterial substances secreted by Paneth cells and goblet cells in the jejunum, ileum and colon; and (3) the activation of TLR4-nuclear factor kappa B (NF-κB), mitogen-activated protein kinases (MAPK), and phosphoinositide-3-kinases (PI3K)/PI3K-protein kinase B (Akt) signaling pathways in the jejunum and ileum. In the jejunum, glutamine supplementation decreased the abundance of Firmicutes, while increased mRNA levels for antibacterial substances in association with the activation of NF-κB and PI3K-Akt pathways. In the ileum, glutamine supplementation induced a shift in the Firmicutes:Bacteroidetes ratio in favor of Bacteroidetes, and enhanced mRNA levels for Tlr4, pro-inflammatory cytokines, and antibacterial substances participating in NF-κB and JNK signaling pathways. These results indicate that the effects of glutamine on the intestine vary with its segments and compartments. Collectively, dietary glutamine supplementation of mice beneficially alters intestinal bacterial community and activates the innate immunity in the small intestine through NF-κB, MAPK and PI3K-Akt signaling pathways.

The role of total parenteral nutrition in inflammatory bowel disease: current aspects

Total parenteral nutrition (TPN) represents a therapeutic modality that could save the life of a patient with inflammatory bowel disease (IBD) facing severe nutritional problems, by restoring the patient's impaired nutritional status. TPN does not compete with enteral nutrition (EN), the latter being the first choice for all patients having anatomically intact and functionally normal digestive tract. TPN allows bowel rest while supplying adequate calorific intake and essential nutrients, and removes antigenic mucosal stimuli. The value of TPN in malnourished patients with intestinal failure due to CD is beyond doubt. However, it is difficult to suggest TPN as a sole treatment for active CD. An increased rate of remission could not be expected by applying TPN. The utility of TPN is restricted to certain cases involving efforts to close enterocutaneous or other complicated fistulas in patients with fistulizing CD, the treatment of short bowel syndrome following extensive resections for CD, or when EN is impractical for other reasons. There are no advantages of TPN therapy over EN therapy regarding fistula healing. TPN has no influence on the surgical intervention rate and little benefit by bypassing the intestinal passage could be expected. Also TPN shows no advantage if the disease is chronically active. However, an optimal supply of nutrients improves bowel motility, intestinal permeability and nutritional status, and reduces inflammatory reactions. TPN might be associated with an increased risk of adverse events, although TPN undertaken by experienced teams does not cause more complications than does EN.

Oral free and dipeptide forms of glutamine supplementation attenuate oxidative stress and inflammation induced by endotoxemia

OBJECTIVE

The aim of the present study was to determine the effects of oral supplementation with L-glutamine plus L-alanine (GLN+ALA), both in the free form and L-alanyl-L-glutamine dipeptide (DIP) in endotoxemic mice.

METHODS

B6.129 F2/J mice were subjected to endotoxemia (Escherichia coli lipopolysaccharide [LPS], 5 mg/kg, LPS group) and orally supplemented for 48 h with either L-glutamine (1 g/kg) plus L-alanine (0.61 g/kg) (GLN+ALA-LPS group) or 1.49 g/kg DIP (DIP-LPS group). Plasma glutamine, cytokines, and lymphocyte proliferation were measured. Liver and skeletal muscle glutamine, glutathione (GSH), oxidized GSH (GSSG), tissue lipoperoxidation (TBARS), and nuclear factor (NF)-κB-interleukin-1 receptor-associated kinase 1 (IRAK1)-Myeloid differentiation primary response gene 88 pathway also were determined.

RESULTS

Endotoxemia depleted plasma (by 71%), muscle (by 44%), and liver (by 49%) glutamine concentrations (relative to the control group), which were restored in both GLN+ALA-LPS and DIP-LPS groups (P < 0.05). Supplemented groups reestablished GSH content, intracellular redox status (GSSG/GSH ratio), and TBARS concentration in muscle and liver (P < 0.05). T- and B-lymphocyte proliferation increased in supplemented groups compared with controls and LPS group (P < 0.05). Tumor necrosis factor-α, interleukin (IL)-6, IL-1 β, and IL-10 increased in LPS group but were attenuated by the supplements (P < 0.05). Endotoxemic mice exhibited higher muscle gene expression of components of the NF-κB pathway, with the phosphorylation of IκB kinase-α/β. These returned to basal levels (relative to the control group) in both GLN+ALA-LPS and DIP-LPS groups (P < 0.05). Higher mRNA of IRAK1 and MyD88 were observed in muscle of LPS group compared with the control and supplemented groups (P < 0.05).

CONCLUSION

Oral supplementations with GLN+ALA or DIP are effective in attenuating oxidative stress and the proinflammatory responses induced by endotoxemia in mice.

Monitoring immune modulation by nutrition in the general population: identifying and substantiating effects on human health

Optimal functioning of the immune system is crucial to human health, and nutrition is one of the major exogenous factors modulating different aspects of immune function. Currently, no single marker is available to predict the effect of a dietary intervention on different aspects of immune function. To provide further guidance on the assessment and interpretation of the modulation of immune functions due to nutrition in the general population, International Life Sciences Institute Europe commissioned a group of experts from academia, government and the food industry to prepare a guidance document. A draft of this paper was refined at a workshop involving additional experts. First, the expert group defined criteria to evaluate the usefulness of immune function markers. Over seventy-five markers were scored within the context of three distinct immune system functions: defence against pathogens; avoidance or mitigation of allergy; control of low-grade (metabolic) inflammation. The most useful markers were subsequently classified depending on whether they by themselves signify clinical relevance and/or involvement of immune function. Next, five theoretical scenarios were drafted describing potential changes in the values of markers compared with a relevant reference range. Finally, all elements were combined, providing a framework to aid the design and interpretation of studies assessing the effects of nutrition on immune function. This stepwise approach offers a clear rationale for selecting markers for future trials and provides a framework for the interpretation of outcomes. A similar stepwise approach may also be useful to rationalise the selection and interpretation of markers for other physiological processes critical to the maintenance of health and well-being.

Effect of parenteral l-alanyl-l-glutamine administration on phagocytic responses of polymorphonuclear neutrophilic leukocytes in dogs undergoing high-dose methylprednisolone sodium succinate treatment

OBJECTIVE

To determine whether parenteral l-alanyl-l-glutamine (Ala-Gln) administration modulated phagocytic responses of polymorphonuclear neutrophilic leukocytes (PMNs) from dogs undergoing high-dose methylprednisolone sodium succinate (MPSS) treatment.

ANIMALS

15 healthy Beagles.

PROCEDURES

Dogs were randomly assigned to 3 treatment groups (n = 5/group): 38-hour IV infusion of saline (0.9% NaCl) solution (control group), saline solution with 8.5% amino acids (2.3 g/kg/d), or saline solution with 8.5% amino acids (1.8 g/kg/d) and 20% l-alanyl-l-glutamine (Ala-Gln; 0.5 g/kg/d). High-dose MPSS treatment was initiated at the same time that IV infusions began, such that a total dose of 85 mg of MPSS/kg was administered through multiple IV injections over a 26-hour period. The infusions were maintained until 12 hours after the last MPSS injection. Blood samples collected before MPSS injections began and 2, 12, and 24 hours after injections ceased were used to evaluate PMN function.

RESULTS

MPSS injections resulted in an increase in the total number of circulating leukocytes and increases in neutrophil and monocyte counts but did not affect lymphocyte, eosinophil, or basophil counts. Lymphocyte counts in the Ala-Gln group were higher than in the control group 12 hours after MPSS injections finished. Relative to preinfusion values, phagocytic capacity, oxidative burst activity, and filamentous actin polymerization of PMNs were suppressed in all dogs except those that received Ala-Gln.

CONCLUSIONS AND CLINICAL RELEVANCE

Parenteral Ala-Gln administration in dogs resulted in an increase in PMN phagocytic responses that were suppressed by high-dose MPSS treatment.

Glutamate and CO2 production from glutamine in incubated enterocytes of adult and very old rats

Glutamine is the major fuel for enterocytes and promotes the growth of intestinal mucosa. Although oral glutamine exerts a positive effect on intestinal villus height in very old rats, how glutamine is used by enterocytes is unclear. Adult (8 months) and very old (27 months) female rats were exposed to intermittent glutamine supplementation for 50% of their age lifetime. Treated rats received glutamine added to their drinking water, and control rats received water alone. Jejunal epithelial cells (~300×10(6) cells) were incubated in oxygenated Krebs-Henseleit buffer for 30 min containing [1-(13)C] glutamine (~17 M) for analysis of glutamine metabolites by (13)C nuclear magnetic resonance ((13)C NMR). An aliquot fraction was incubated in the presence of [U-(14)C] glutamine to measure produced CO2. Glutamine pretreatment increased glutamate production and decreased CO2 production in very old rats. The ratio CO2/glutamate, which was very high in control very old rats, was similar at both ages after glutamine pretreatment, as if enterocytes from very old rats recovered the metabolic abilities of enterocytes from adult rats. Our results suggest that long-term treatment with glutamine started before advanced age (a) prevented the loss of rat body weight without limiting sarcopenia and (b) had a beneficial effect on enterocytes from very old rats probably by favoring the role of glutamate as a precursor for glutathione, arginine and proline biosynthesis, which was not detected in (13)C NMR spectra in our experimental conditions.

Improvements of immune status, intestinal integrity and gain performance in the early-weaned calves parenterally supplemented with L-alanyl-L-glutamine dipeptide

Glutamine (Gln) is an important substrate for the innate immune cells including lymphocytes and macrophages. In this report, the effects of alanyl-glutamine dipeptide (Ala-Gln) on the naïve immune system, intestinal integrity and gain performance of early-weaned calves were investigated. Early-weaned Chinese Holstein calves were intravenously administered different dosages of Ala-Gln. The effects of Ala-Gln administration were ascertained by evaluating the blood for naïve T lymphocyte subpopulations, the concentrations of serum IgG, serum IgA and intestinal mucosal secretory IgA (s-IgA), the intestinal integrity, as well as the gain performance. Results demonstrated that intravenous administration of Ala-Gln dipeptide (1.01 g/kg×d(-1)) for 7 days had a positive effect on gain performance, intestinal integrity and the immune system. Calves administered doses of Ala-Gln displayed an improvement in gain performance and health status concurrent with increases in blood CD2(+) and CD4(+) lymphocytes, the ratio of CD4(+)/CD8(+), serum IgA and IgG, intestinal mucosal s-IgA while decreasing the occurrence of diarrhea. Moreover, we found that animals given the effective dose (1.01 g/kg×d(-1)) of Ala-Gln resulted in improved immune status and intestinal integrity relative to those given a lower (0.49 g/kg×d(-1)) or higher dose (1.99 g/kg×d(-1)) of Ala-Gln. These findings suggest that maintaining a certain concentration of plasma and/or tissue glutamine in the early stages of weaning is an effective alternative approach for improvement of growth performance in early-wean calves.