Glutamine supplementation enhances mucosal immunity in rats with Gut-Derived sepsis

Usefulness of Perioperative Nutritional Therapy with the Glutamine/Arginine/Calcium β-Hydroxy-β-Methylbutyrate Product in Esophageal Cancer Surgery: A Single-Center Retrospective Study

A useful perioperative nutritional therapy for highly invasive esophageal cancer surgical cases needs to be developed. We clarified the usefulness of amino-acid-enriched nutritional therapy using glutamine (Gln)/arginine (Arg)/calcium β-hydroxy-β-methylbutyrate (HMB) products on the short-term postoperative outcomes of minimally invasive esophagectomy for esophageal cancer. Altogether, 114 patients (Gln/Arg/HMB group) received perioperative nutritional therapy with Gln/Arg/HMB products, and we retrospectively investigated the change in nutritional parameters including skeletal muscle mass, occurrence of postoperative complications, and short-term postoperative outcomes in this group. The results were compared between the Gln/Arg/HMB and control groups (79 patients not receiving the Gln/Arg/HMB products). The incidence of all postoperative complications, sputum expectoration disorder, and pleural effusion of grade ≥ III was significantly lower in the Gln/Arg/HMB group (62.0% vs. 38.6%, p = 0.001; 44.3% vs. 28.1%, p = 0.020; 27.8% vs. 13.2%, p = 0.011, respectively). The psoas muscle area and postoperative body weight were significantly higher at 1 month and 1 year after surgery in the Gln/Arg/HMB group than in the control group (93.5% vs. 99.9%, p < 0.001; 92.0% vs. 95.4%, p = 0.006). Perioperative amino-acid-enriched nutritional therapy may improve the short-term postoperative outcomes, nutritional status, and skeletal muscle mass of esophageal cancer surgical patients.

Restoration of the Mucosal IgA Response by Improving CD4+ T Pyroptosis Fails to Attenuate Gut Bacterial Translocation and Organ Damage After LPS Attack

BACKGROUND

Currently, the mechanisms of impaired gut mucosal immunity in sepsis remain unclear. Gut immunoglobulin A (IgA) is an important defense mechanism against invasive pathogens, and CD4+ T cells regulate the IgA response.

AIM

We aimed to verify the hypothesis indicating that CD4+ T pyroptosis induced by lipopolysaccharide (LPS) leads to an impaired gut IgA response and subsequent bacterial translocation and organ damage.

METHODS

Cultured CD4+ T cells and mice were manipulated with LPS, and pyroptosis was improved by A438079 or adoptive CD4+ T cell transfer. The changes demonstrated in pyroptosis-related molecules, cytotoxicity and CD4+ T cells were examined to determine CD4+ T pyroptosis. The changes demonstrated in IgA+ B cells, AID (key enzyme for immunoglobulins) and IgA production and function were examined to evaluate the IgA response. Serum biomarkers, bacterial colonies and survival analysis were detected for bacterial translocation and organ damage.

RESULTS

LPS attack induced CD4+ T pyroptosis, as evidenced by increased expression of P2X7, Caspase-11 and cleaved GSDMD, which elevated cytotoxicity and decreased CD4+ T cells. Decreased CD4+ T subsets (Foxp3+ T and Tfh cells) influenced the IgA response, as evidenced by lower AID expression, which decreased IgA+ B cells and IgA production and function. A438079 or cell transfer improved the IgA response but failed to reduce the translocation of gut pathogens, damage to the liver and kidney, and mortality of mice.

CONCLUSION

LPS attack results in CD4+ T pyroptosis. Improvement of pyroptosis restores the mucosal IgA response but fails to ameliorate bacterial translocation and organ damage.

Immunological effects of glutamine supplementation in polytrauma patients in intensive care unit

Background

In polytrauma intensive care unit (ICU) patients, glutamine (GLN) becomes a “conditionally essential” amino acid; its role has been extensively studied in numerous clinical trials but their results are inconclusive.

We evaluated the IgA-mediated humoral immunity after GLN supplementation in polytrauma ICU patients.

Methods

All consecutive patients with polytrauma who required mechanical ventilation and enteral nutrition (EN) provided within 24 h since the admission in ICU at the University Hospital of Foggia from September 2016 to February 2017 were included.

Thereafter, two groups were identified: patients treated by conventional EN (25 kcal/kg/die) and patients who have received conventional EN enriched with 50 mg/kg/ideal body weight of alanyl-GLN 20% intravenously.

We analysed the plasmatic concentration of IgA, CD3+/CD4+ T helper lymphocytes, CD3+/CD8+ T suppressor lymphocytes, CD3+/CD19+ B lymphocytes, IL-4 and IL-2 at admission and at 4 and 8 days.

Results

We identified 30 patients, with 15 subjects per group. IgA levels increased significantly in GLN vs the control group at T0, T4 and T8. CD3+/CD4+ T helper lymphocyte and CD3+/CD8+ T suppressor lymphocyte levels significantly increased in GLN vs the control group at T4 and T8. CD3+/CD19+ B lymphocyte levels increased significantly in GLN vs the control group only at T8. IL-2 and IL-4 levels showed no significant differences when comparing GLN with the control group.

Conclusions

Our study showed that there was an improvement in humoral and cell-mediated immunity with GLN supplementation in polytrauma ICU patients using recommended doses.

Dietary Glutamine Inclusion Regulates Immune and Antioxidant System, as Well as Programmed Cell Death in Fish to Protect against Flavobacterium columnare Infection

The susceptibility of animals to pathogenic infection is significantly affected by nutritional status. The present study took yellow catfish (Pelteobagrus fulvidraco) as a model to test the hypothesis that the protective roles of glutamine during bacterial infection are largely related to its regulation on the immune and antioxidant system, apoptosis and autophagy. Dietary glutamine supplementation significantly improved fish growth performance and feed utilization. After a challenge with Flavobacterium columnare, glutamine supplementation promoted il-8 and il-1β expression via NF-κB signaling in the head kidney and spleen, but inhibited the over-inflammation in the gut and gills. Additionally, dietary glutamine inclusion also enhanced the systematic antioxidant capacity. Histological analysis showed the protective role of glutamine in gill structures. Further study indicated that glutamine alleviated apoptosis during bacterial infection, along with the reduced protein levels of caspase-3 and the reduced expression of apoptosis-related genes. Moreover, glutamine also showed an inhibitory role in autophagy which was due to the increased activation of the mTOR signaling pathway. Thus, our study for the first time illustrated the regulatory roles of glutamine in the fish immune and antioxidant system, and reported its inhibitory effects on fish apoptosis and autophagy during bacterial infection.

The Effect of Amino Acids on Wound Healing: A Systematic Review and Meta-Analysis on Arginine and Glutamine

Under stress conditions, the metabolic demand for nutrients increases, which, if not met, may slow down or indeed stop the wound from healing, thus, becoming chronic wounds. This study aims to perform a systematic review and meta-analysis of the effect of arginine and glutamine supplementation on wound healing. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed for the systematic review and ten electronic databases were used. Five and 39 human studies met the inclusion criteria for arginine and glutamine, respectively. The overall meta-analysis demonstrated a significant effect of arginine supplementation on hydroxyproline content (MD: 4.49, 95% CI: 3.54, 4.45, p < 0.00001). Regarding glutamine supplementation, there was significant effect on nitrogen balance levels (MD: 0.39, 95% CI: 0.21, 0.58, p < 0.0001), IL-6 levels (MD: −5.78, 95% CI: −8.71, −2.86, p = 0.0001), TNFα levels (MD: −8.15, 95% CI: −9.34, −6.96, p < 0.00001), lactulose/mannitol (L/M) ratio (MD: −0.01, 95% CI: −0.02, −0.01, p < 0.00001), patient mortality (OR: 0.48, 95% CI: 0.32, 0.72, p = 0.0004), C-reactive protein (CRP) levels (MD: −1.10, 95% CI: −1.26, −0.93, p < 0.00001) and length of hospital stay (LOS) (MD: −2.65, 95% CI: −3.10, −2.21, p < 0.00001). Regarding T-cell lymphocytes, a slight decrease was observed, although it failed to reach significance (MD: −0.16, 95% CI: −0.33, 0.01, p = 0.07). Conclusion: The wound healing might be enhanced in one or at various stages by nutritional supplementation in the right dose.

Glutamine alleviates heat stress-induced impairment of intestinal morphology, intestinal inflammatory response, and barrier integrity in broilers

The aim of this study was to investigate the protective effect of glutamine (Gln) on the intestinal morphology, intestinal inflammatory response, and barrier integrity in broilers exposed to high ambient temperature. Three-hundred-sixty 21-d-old Arbor Acres broilers (half male and half female) were randomly allocated to 4 treatment groups in a completely randomized design, each of which included 6 replicates with 15 birds per replicate, for 21 d. The 4 treatment groups were as follows: the control group, in which birds were kept in a thermoneutral room at 22 ± 1°C (no stress, NS; fed a basal diet); the heat stress group (36 ± 1°C for 10 h/d from 08:00 to 18:00 h and 22 ± 1°C for the remaining time, heat stress (HT); fed a basal diet); and heat stress + Gln group (0.5 and 1.0% Gln, respectively). Compared to the NS group, broilers in the HT group had lower villus height (P < 0.05), higher crypt depth (P < 0.05), higher D-lactic acid and diamine oxidase (DAO) activity (P < 0.05), higher soluble intercellular adhesion molecule-1 (sICAM-1) concentration (P < 0.05), higher tumor necrosis factor (TNF)-α/interleukin (IL)-10 (P < 0.05), and lower tight junction protein expression levels (P < 0.05). Compared with birds in the HT, birds in the HT + Gln group exhibited increased villus height (P < 0.05), decreased D-lactate and DAO activity (P < 0.05), decreased sICAM-1 concentration (P < 0.05), and mediate the secretion of cytokines (P < 0.05), as well as increased zonula occludens-1 (ZO-1), claudin-1, and occludin mRNA expression levels (P < 0.05). In conclusion, these results indicate that supplementation with Gln was effective in partially ameliorating the adverse effects of heat stress on intestinal barrier function in broilers by promoting epithelial cell proliferation and renewal, modifying the function of the intestinal mucosa barrier, and regulating the secretion of cytokines.

l-Glutamine Attenuates DSS-Induced Colitis via Induction of MAPK Phosphatase-1

Inflammatory bowel disease (IBD), encompassing ulcerative colitis and Crohn’s disease, is a multifactorial inflammatory disease of the small intestine and colon. Many investigators have reported that l-glutamine (Gln) therapy improves outcomes of experimental colitis models, although the mechanism is not fully understood. Regarding the anti-inflammatory properties of Gln, we have shown that Gln can effectively deactivate cytosolic phospholipase A₂ (cPLA₂) by rapid induction of MAPK phosphatase (MKP)-1. In this study, we explore the possibility that Gln ameliorates dextran sulfate sodium (DSS)-induced colitis via MKP-1 induction, resulting in inhibition of cPLA₂, which has been reported to play a key role in the pathogenesis of IBD. Oral Gln intake attenuated DSS-induced colitis. Gln inhibited cPLA₂ phosphorylation, as well as colonic levels of TNF-α and leukotriene (LT)B₄. Gln administration resulted in early and enhanced MKP-1 induction. Importantly, MKP-1 small interfering RNA (siRNA), but not control siRNA, significantly abrogated the Gln-mediated (1) induction of MKP-1; (2) attenuation of colitis (colon length, histological abnormality, and inflammation; and (3) inhibition of cPLA₂ phosphorylation and colonic levels of TNF-α and LTB₄. These data indicated that Gln ameliorated DSS-induced colitis via MKP-1 induction.

n-3 Polyunsaturated Fatty Acids Improve Inflammation via Inhibiting Sphingosine Kinase 1 in a Rat Model of Parenteral Nutrition and CLP-Induced Sepsis

The sphingosine kinase 1 (SphK1)/sphingosine-1-phosphate (S1P) pathway plays a key role in inflammation. Parenteral nutrition containing n-3 polyunsaturated fatty acids (n-3 PUFA) may regulate inflammatory reactions. The aim of this study is to determine whether n-3 PUFA may improve inflammatory responses by neutralizing SphK1 signaling. Rat models of parenteral nutrition, cecal ligation and puncture (CLP)-induced sepsis were generated. Male Sprague-Dawley rats were operated for CLP on day 2 after venous catheterization. The rats were randomized to receive normal saline (NS; n = 20), parenteral nutrition (PN; n = 20), or PN + fish oil (FO; n = 20) for 5 days. The daily intake of fish oil (1.25-2.82 g EPA and 1.44-3.09 g DHA per 100 ml) in the FO group was approximately 1.8 g/kg body weight/day. Rats in the control group (n = 10) were subjected to sham operation and received a chow diet. Spleen tissues were collected for SphK1 and S1P receptor expression analysis. Our data showed that n-3 PUFA ameliorated the survival rate. SphK1 expression and its enzymatic activity were significantly upregulated in sepsis rats. Furthermore, mRNA and protein levels of S1PR3, but not S1PR1, were also facilitated after CLP. However, PN + FO dramatically decreased SphK1 mRNA level and its enzymatic activity. S1PR3 expression was also attenuated by FO addition. In conclusion, the anti-inflammatory effect of n-3 PUFA may be linked to the inhibition of the SphK1/S1P pathway in a rat model of parenteral nutrition and CLP-induced sepsis.

Short-term glutamine supplementation decreases lung inflammation and the receptor for advanced glycation end-products expression in direct acute lung injury in mice

Background

Glutamine (GLN) has been reported to improve clinical and experimental sepsis outcomes. However, the mechanisms underlying the actions of GLN remain unclear, and may depend upon the route of GLN administration and the model of acute lung injury (ALI) used. The aim of this study was to investigate whether short-term GLN supplementation had an ameliorative effect on the inflammation induced by direct acid and lipopolysaccharide (LPS) challenge in mice.

Methods

Female BALB/c mice were divided into two groups, a control group and a GLN group (4.17% GLN supplementation). After a 10-day feeding period, ALI was induced by intratracheal administration of hydrochloric acid (pH 1.0; 2 mL/kg of body weight [BW]) and LPS (5 mg/kg BW). Mice were sacrificed 3 h after ALI challenge. In this early phase of ALI, serum, lungs, and bronchoalveolar lavage fluid (BALF) from the mice were collected for further analysis.

Results

The results of this study showed that ALI-challenged mice had a significant increase in myeloperoxidase activity and expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α in the lung compared with unchallenged mice. Compared with the control group, GLN pretreatment in ALI-challenged mice reduced the levels of receptor for advanced glycation end-products (RAGE) and IL-1β production in BALF, with a corresponding decrease in their mRNA expression. The GLN group also had markedly lower in mRNA expression of cyclooxygenase-2 and NADPH oxidase-1.

Conclusions

These results suggest that the benefit of dietary GLN may be partly contributed to an inhibitory effect on RAGE expression and pro-inflammatory cytokines production at an early stage in direct acid and LPS-induced ALI in mice.

The immune modifying effects of amino acids on gut-associated lymphoid tissue

The intestine and the gut-associated lymphoid tissue (GALT) are essential components of whole body immune defense, protecting the body from foreign antigens and pathogens, while allowing tolerance to commensal bacteria and dietary antigens. The requirement for protein to support the immune system is well established. Less is known regarding the immune modifying properties of individual amino acids, particularly on the GALT. Both oral and parenteral feeding studies have established convincing evidence that not only the total protein intake, but the availability of specific dietary amino acids (in particular glutamine, glutamate, and arginine, and perhaps methionine, cysteine and threonine) are essential to optimizing the immune functions of the intestine and the proximal resident immune cells. These amino acids each have unique properties that include, maintaining the integrity, growth and function of the intestine, as well as normalizing inflammatory cytokine secretion and improving T-lymphocyte numbers, specific T cell functions, and the secretion of IgA by lamina propria cells. Our understanding of this area has come from studies that have supplemented single amino acids to a mixed protein diet and measuring the effect on specific immune parameters. Future studies should be designed using amino acid mixtures that target a number of specific functions of GALT in order to optimize immune function in domestic animals and humans during critical periods of development and various disease states.

Intestinal mucosal atrophy and adaptation

Mucosal adaptation is an essential process in gut homeostasis. The intestinal mucosa adapts to a range of pathological conditions including starvation, short-gut syndrome, obesity, and bariatric surgery. Broadly, these adaptive functions can be grouped into proliferation and differentiation. These are influenced by diverse interactions with hormonal, immune, dietary, nervous, and mechanical stimuli. It seems likely that clinical outcomes can be improved by manipulating the physiology of adaptation. This review will summarize current understanding of the basic science surrounding adaptation, delineate the wide range of potential targets for therapeutic intervention, and discuss how these might be incorporated into an overall treatment plan. Deeper insight into the physiologic basis of adaptation will identify further targets for intervention to improve clinical outcomes.

Intravenous free and dipeptide-bound glutamine maintains intestinal microcirculation in experimental endotoxemia

OBJECTIVE

The administration of glutamine (Gln), which is depleted in critical illness, is associated with an improvement of gut metabolism, structure, and function. The aim of the present study was to evaluate the effects of intravenous Gln and its galenic formulation, l-alanyl-l-glutamine dipeptide (AlaGln), on the intestinal microcirculation during experimental endotoxemia using intravital fluorescence microscopy. Gln or AlaGln administration was performed as pretreatment or post-treatment, respectively. To identify further the underlying mechanisms, amino acid levels were studied.

METHODS

Sixty male Lewis rats were randomly divided into six groups (n = 10/group): control, LPS (lipopolysaccharide 5 mg/kg intravenously), Gln/LPS (LPS animals pretreated with Gln 0.75 g/kg Gln intravenously), AlaGln/LPS (LPS animals pretreated with AlaGln intravenously, 0.75 g/kg Gln content), LPS/Gln (LPS animals post-treated with Gln 0.75 g/kg intravenously), and LPS/AlaGln (LPS animals post-treated with AlaGln intravenously, 0.75 g/kg Gln content). Two hours after the endotoxin challenge, the microcirculation of the terminal ileum was studied using intravital fluorescence microscopy. Blood samples were drawn at the beginning, during, and the end of the experiment to determine the amino acid levels.

RESULTS

The Gln and AlaGln pre- and post-treatment, respectively, prevented the LPS-induced decrease in the functional capillary density of the intestinal muscular and mucosal layers (P < 0.05). The number of adherent leukocytes in the submucosal venules was significantly attenuated after the Gln and AlaGln pre- and post-treatment (P < 0.05).

CONCLUSION

The Gln and AlaGln administrations improved the intestinal microcirculation by increasing the functional capillary density of the intestinal wall and decreasing the submucosal leukocyte activation.

Glutamine therapy improves outcome of in vitro and in vivo experimental colitis models

BACKGROUND

Pharmacologic doses of glutamine (GLN) can improve clinical outcome following acute illness and injury. Recent studies indicate enhanced heat shock protein (HSP) expression is a key mechanism underlying GLN's protection. However, such a link has not yet been tested in chronic inflammatory states, such as experimental inflammatory bowel disease (IBD).

METHODS

Experimental colitis was induced in Sprague-Dawley rats via oral 5% dextran sulfate sodium (DSS) for 7 days. GLN (0.75 g/kg/d) or sham was administered to rats by oral gavage during 7-day DSS treatment. In vitro inflammatory injury was studied using YAMC colonic epithelial cells treated with varying concentrations of GLN and cytokines (tumor necrosis factor-α/interferon-γ).

RESULTS

Pharmacologic dose, bolus GLN attenuated DSS-induced colitis in vivo with decreased area under curve for bleeding (8.06 ± 0.87 vs 10.38 ± 0.79, P < .05) and diarrhea (6.97 ± 0.46 vs 8.53 ± 0.39, P < .05). This was associated with enhanced HSP25 and HSP70 in colonic mucosa. In vitro, GLN enhanced cell survival and reduced proapoptotic caspase3 and poly(ADP-ribose) polymerase cleavage postcytokine injury. Cytokine-induced inducible nitric oxide synthase expression and nuclear translocation of nuclear factor-κB p65 subunit were markedly attenuated at GLN concentrations above 0.5 mmol/L. GLN increased cellular HSP25 and HSP70 in a dose-dependent manner.

CONCLUSIONS

These data demonstrate the therapeutic potential of GLN as a "pharmacologically acting nutrient" in the setting of experimental IBD. GLN sufficiency is crucial for the colonic epithelium to mount a cell-protective, antiapoptotic, and anti-inflammatory response against inflammatory injury. The enhanced HSP expression observed following GLN treatment may be responsible for this protective effect.

Effects of early enteral glutamine supplementation on lymphocyte subpopulations in Peyer's patches in scalded rats

AIM: To investigate the changes in the number of total lymphocytes and each lymphocyte subpopulation in Peyer's patches in scalded rats receiving different nutrition support, and examine the effects of glutamine (Gln) supplementation on intestinal immunity.

METHODS: Healthy adult Sprague-Dawley rats were subjected to a 30% TBSA third-degree scald injury to induce scald injury. Scalded rats were randomly divided into standard enteral nutrition group (EN group) and glutamine supplementation group (EN plus Gln group). Rats in the EN group were fed standard enteral nutrition (Nutrison Multi Fibre) while those in the EN plus Gln group were fed standard enteral nutrition plus Gln. The number of total lymphocytes and each lymphocyte subpopulation in Peyer's patches were then determined by flow cytometry on days 1, 4, 7 and 10 after feeding.

RESULTS: The number of total lymphocytes, especially B lymphocytes, in Peyer's patches significantly decreased in response to scald induction. The number of total lymphocytes in Peyer's patches in rats in the EN plus Gln group, but not in the EN group, returned to normal on day 7 after scald induction [(5.29 ± 1.03) × 10⁶vs (6.13 ± 1.14) × 10⁶, P > 0.05]. The total number of B cells in Peyer's patches in rats in the EN plus Gln group on days 7 and 10 showed no significant changes when compared with pre-induction value [(2.87 ± 0.69) × 10⁶ and (3.05 ± 0.72) × 10⁶vs (3.29 ± 0.62) × 10⁶, respectively; both P> 0.05]. In contrast, the total number of B cells in Peyer's patches in rats in the EN group on day 10 was significantly lower than pre-induction value [(2.07 ± 0.63) × 10⁶vs (3.29 ± 0.62) × 10⁶; P < 0.05]. Scald induction had no significant effect on the number of CD4⁺ and CD8⁺ lymphocytes (both P > 0.05).

CONCLUSION: The number of total lymphocytes decreases significantly in response to scald induction. Early enteral glutamine supplementation can promote lymphocyte proliferation, increase the number of total lymphocytes (especially B cells) in Peyer's patches, and enhance intestinal immunity in scalded rats.

Molecular mechanisms of pharmaconutrients

Nutritional supplementation has become the standard of care for management of critically ill patients. Traditionally, nutritional support in this patient population was intended to replete substrate deficiencies secondary to stress-induced catabolism. Recognition of the influence of certain nutrients on the immune and inflammatory response of the critically ill has led to the evolution of more sophisticated nutritional strategies and concepts. Administration of immune-enhancing formulas supplemented with a combination of glutamine, arginine, omega-3 fatty acids (omega-3 FA), and nucleotides have been shown in most studies to reduce infectious outcomes. More recently, the separation of nutritional support from the provision of key nutrients has led to a further appreciation of the immunomodulatory and anti-inflammatory benefits of isolated nutrients, such as glutamine and antioxidants. The purpose of this article is to review the molecular mechanisms that are unique to each class of frequently utilized nutrients. A better understanding of the specific molecular targets of immunonutrients will facilitate application of more refined nutritional therapies in critically ill patients.

Single and combined supplementation of glutamine and n-3 polyunsaturated fatty acids on host tolerance and tumour response to 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxy-camptothecin (CPT-11)/5-fluorouracil chemotherapy in rats bearing Ward colon tumour

Prior reports suggest that during irinotecan (7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxy-camptothecin; CPT-11) chemotherapy in laboratory rats, the anti-tumour efficacy and diarrhoea toxicity could be modulated by n-3 PUFA and glutamine, respectively. We further examined how these two dietary elements, when provided individually and in combination, would affect the efficacy of a cyclical regimen of CPT-11/5-fluorouracil (5-FU), an accepted combination regimen for colorectal cancer. Prior to initiating chemotherapy, diets enriched either with glutamine (2 %, w/w total diet) or n-3 PUFA (0.88 %, w/w total diet) alone, inhibited Ward colon tumour growth (P < 0.05). These diets also completely or partially normalized the changes in peripheral leucocyte counts associated with the tumour-bearing state (e.g. neutrophil proportion/concentration and lymphocyte proportion). During chemotherapy, either glutamine- or n-3 PUFA-enriched diet enhanced tumour chemo-sensitivity, and reduced body weight loss, anorexia and muscle wasting (v. animals fed control diet, P < 0.05). Surprisingly, providing both glutamine and n-3 PUFA together did not confer a greater benefit on tumour inhibition either in the presence or absence of chemotherapy; individual benefits associated with single treatments, particularly in respect to host nutritional status (i.e. body weight, food intake and muscle weight) and immune (peripheral leucocyte counts) features were instead partially or completely lost when these two nutrients were combined. These results draw into question the common assumption that there are additive or synergistic benefits of combinations of nutrients, which are beneficial on an individual basis, and suggest that co-supplementation with glutamine and n-3 PUFA is not indicated during chemotherapy with CPT-11 and 5-FU.

Glutamine reduces TNF-alpha by enhancing glutathione synthesis in lipopolysaccharide-stimulated alveolar epithelial cells of rats

To investigate the role of glutathione (GSH) synthesis in the regulation on nuclear factor (NF)-kappaB activity and tumor necrosis factor-alpha (TNF-alpha) release by glutamine (GLN) in lipopolysaccharide (LPS)-stimulated alveolar type II (AT-II) epithelial cells of rat lungs. Primary cultured AT-II cells were pre-treated with various doses of GLN for 2, 8, 16, 24 h. At the 8 h time point before LPS stimulation, various doses of L: -buthionine-(S,R)-sulfoximine (BSO), an inhibitor of GSH synthesis, were added with 10 mM GLN. Then the cells were stimulated with 1 mug/ml LPS for 24 h. The cells were obtained for GSH measurement. TNF-alpha level in the supernatant was determined by enzyme-linked immunosorbent assay. NF-kappaB activity was assessed by electrophoretic mobility shift assay. Eight hours before LPS exposure was the best time point for GLN's enhancing GSH synthesis. LPS could significantly decrease the GSH level, increase NF-kappaB activation and TNF-alpha release in AT-II cells. Supplementation of GLN could increase the GSH level and attenuate the release of TNF-alpha in LPS-stimulated AT-II cells in a dose-dependant manner. And NF-kappaB activation also could be prevented by GLN. BSO could block the effect of GLN. As a precursor of GSH, glutamine could prevent the NF-kappaB activation and attenuate the release of TNF-alpha in LPS-stimulated AT-II cells and the effect may be mediated via GSH synthesis.

Nutritional modulation of antitumor efficacy and diarrhea toxicity related to irinotecan chemotherapy in rats bearing the ward colon tumor

PURPOSE

To evaluate and compare the influence of dietary elements on cancer progression, chemotherapy efficacy, and toxicity, particularly severe, late-onset diarrhea related to irinotecan (CPT-11) treatment.

EXPERIMENTAL DESIGN

We used laboratory rats fed a standardized basal diet, Ward colon tumor, and CPT-11 therapy for the study of CPT-11-induced diarrhea. Dietary interventions were selected from nutrients already established to modify other forms of colitis and which have been hypothesized to mitigate chemotherapy-induced gastrointestinal injury (glutamine, n-3 fatty acids, prebiotic oligosaccharides). Animals adapted to test diets were treated with CPT-11 at the maximum tolerated dose (125 mg/kg x 3 days) and diarrhea was followed continuously for 1 week.

RESULTS

The inclusion of n-3 fatty acids in the diet (5%, w/w of total fat) suppressed tumor growth and enhanced CPT-11's efficacy; this treatment did not affect the incidence or severity of diarrhea. By contrast, oral glutamine bolus (0.75 g/kg) administered prior to each CPT-11 treatment reduced the incidence of severe diarrhea (34.1 +/- 4.7% versus 53.8 +/- 4.2%, P < 0.005) and decreased the area under the curve of diarrhea score (16.5 +/- 1.0 versus 18.8 +/- 0.5, P < 0.05). Identical results were obtained with i.v. bolus glutamine administration. Glutamine treatment did not alter CPT-11's antitumor efficacy. The addition of prebiotic oligosaccharides to the diet (8%, w/w of diet) did not mitigate the severity of diarrhea, and it raised the activity of beta-glucuronidase in cecal contents, a key bacterial enzyme mediating CPT-11-related intestinal toxicity.

CONCLUSION

Our experiments suggest that glutamine and n-3 fatty acids might be potentially useful adjuncts to CPT-11 treatment.

N-acetyl-L-glutamine, a liquid-stable source of glutamine, partially prevents changes in body weight and on intestinal immunity induced by protein energy malnutrition in pigs

The goal of this study was to evaluate the preventive effect of free glutamine versus N-acetyl-L-glutamine, a liquid-stable source of glutamine, on gut damage induced by protein energy malnutrition in pigs. Healthy pigs (n = 6) were fed a liquid formula for 30 days. Three subgroups of malnourished pigs (n = 6) received daily 20% of the food intake recorded in control group, supplemented with calcium caseinate, glutamine, or N-acetyl-L-glutamine. Body weight was recorded, and small intestinal samples were evaluated for biochemical and immunologic parameters. Suppression in body weight gain was significantly lower in pigs fed with N-acetyl-L-glutamine than in the rest of malnourished pigs. Total number of lymphocytes, CD21+ B cells and CD4+ T cells in ileal Peyer patches were not significantly different in malnourished pigs fed with N-acetyl-L-glutamine and in healthy pigs. In conclusion, N-acetyl-L-glutamine has a moderate protective effect, partially preventing changes induced by protein energy malnutrition.

Effects of ω-3 fatty acids on leukocyte Th1/Th2 cytokine and integrin expression in rats with gut-derived sepsis

OBJECTIVES

This study examined the effect of fish oil (FO)-enriched diets before and/or omega-3 fatty acid-containing total parenteral nutrition (TPN) after sepsis on the distribution of the T-lymphocyte subpopulation, intracellular cytokine, and intestinal immunity in rats with gut-derived sepsis.

METHODS

Rats were assigned to a control or one of four experimental groups. The control group and groups 1 and 2 were fed a semipurified diet, and groups 3 and 4 received FO instead of 20% soybean oil. After feeding the diets for 10 d, sepsis was induced by cecal ligation and puncture (CLP) in the experimental groups, whereas a sham operation was performed in the control group. TPN was maintained for 3 d after the CLP or sham operation. The control group and groups 1 and 3 were infused with conventional TPN, whereas the TPN solution used for groups 2 and 4 were supplemented with FO. All rats were sacrificed 3 d after the operation to examine their immune responses.

RESULTS

Plasma and intestinal immunoglobin A levels were higher in the FO-supplemented groups than in the control group and group 1. Lymphocyte interferon-gamma expression in groups 3 and 4 was significantly lower, whereas interleukin-4 expression was higher than those of the control group and groups 1 and 2. The splenocyte CD4 percentage in groups 3 and 4 and the CD4/CD8 ratio in group 4 were significantly higher than those in group 1.

CONCLUSION

These findings suggest that FO administration before and/or after CLP are not immunosuppressive. FO-enriched diets before or before and after CLP resulted in a T-helper type 2 response and enhanced immunoglobulin A secretion. In addition, the splenocyte CD4 levels and CD4/CD8 ratio were maintained in rats with gut-derived sepsis.

Effects of enteral glutamine supplement on endotoxin translocation and mucosal immune barrier in starved rats

AIM: To investigate the changes in intestinal structure and function as well as the effect of enteral glutamine (GLN) supplement on the endotoxin translocation and immunological function in starved rats.

METHODS: Ninety male Sprague Dawley rats were randomly divided into 3 groups: normal control group (n = 10), starved group (group A, n = 40) and GLN group (group B, n = 40). The rats were sacrificed 3, 5, 7 and 9 d after starvation, respectively. Blood samples were collected from portal vein for the detection of plasma endotoxin and tissue samples removed from ileocecum were observed under light microscope for morphological changes. A contrasting study on the expression of secretary immunoglobulin A (sIgA) and the numbers of CD4⁺, CD8⁺ T lymphocytes were also performed between control group and other groups by immunohistochemical staining method.

RESULTS: The atrophy of intestinal mucosa and villa were observed 3 d after starvation in group A, with the degeneration, necrosis, and shedding of partial mucosal epithelial cells. The changes were gradually deteriorated till the 9^th day after starvation. Those pathological changes were lighter in group B than those in group A on the 3^rd day after starvation and restored to normal on the 5^th day. As the starvation time prolonged, the atrophy, degeneration and necrosis of the mucosal epithelial cells appeared again in group B, but were still lighter than those in group A. The levels of endotoxin were significantly higher 3, 5, 7 and 9 d after starvation in both group A and B than those in the controls, and there were also marked differences between group B and A (322.4 ± 65.1, 389.4 ± 32.6, 464.4 ± 76.6, 413.7 ± 67.2 EU/L vs 527.1 ± 74.9, 546.3 ± 65.7, 623.9 ± 85.9, 587.5 ± 140.8 EU/L, all P < 0.01). The expression of sIgA and the numbers CD4⁺ and CD8⁺ T lymphocytes in intestinal mucosa were reduced significantly in group A and B, in compared with those in the controls (P < 0.05 or P < 0.01), and there were higher levels of sIgA and CD4⁺ and CD8⁺ T lymphocytes in group B than those in group A (P < 0.01).

CONCLUSION: The structure of intestinal mucosa is damaged in the earlier stage of starvation in rats, accompanied by endotoxin translocation and dysfunction of intestinal mucosal immune barrier. Early enteral nourishment of glutamine is helpful for inhibiting endotoxin translocation and improve immune function of intestinal mucosa.

L-alanyl-L-glutamine dipeptide-supplemented total parenteral nutrition reduces infectious complications and glucose intolerance in critically ill patients: the French controlled, randomized, double-blind, multicenter study

OBJECTIVE

Glutamine (Gln)-supplemented total parenteral nutrition (TPN) improves clinical outcome after planned surgery, but the benefits of Gln-TPN for critically ill (intensive care unit; ICU) patients are still debated.

DESIGN

Prospective, double-blind, controlled, randomized trial.

SETTING

ICUs in 16 hospitals in France.

PATIENTS

One-hundred fourteen ICU patients admitted for multiple trauma (38), complicated surgery (65), or pancreatitis (11).

INTERVENTIONS

Patients were randomized to receive isocaloric isonitrogenous TPN via a central venous catheter providing 37.5 kcal and 1.5 g amino acids.kg-1.day-1 supplemented with either L-alanyl-L-glutamine dipeptide (0.5 g.kg-1.day-1; Ala-Gln group, n=58) or L-alanine+L-proline (control group, n=56) over at least 5 days.

MEASUREMENTS AND MAIN RESULTS

Complicated clinical outcome was defined a priori by the occurrence of infectious complications (according to the criteria of the Centers for Disease Control and Prevention), wound complication, or death. The two groups were compared by chi-square test on an intention-to-treat basis. The two groups did not differ at inclusion for type and severity of injury (mean simplified acute physiology score II, 30 vs. 30.5; mean injury severity score, 44.9 vs. 42.3). Similar volumes of TPN were administered in both groups. Ala-Gln-supplemented TPN was associated with a lower incidence of complicated outcome (41% vs. 61%; p<.05), which was mainly due to a reduced infection rate per patient (mean, 0.45 vs. 0.71; p<.05) and incidence of pneumonia (10 vs. 19; p<.05). Early death rate during treatment and 6-month survival were not different. Hyperglycemia was less frequent (20 vs. 30 patients; p<.05) and there were fewer insulin-requiring patients (14 vs. 22; p<.05) in the Ala-Gln group.

CONCLUSIONS

TPN supplemented with Ala-Gln dipeptide in ICU patients is associated with a reduced rate of infectious complications and better metabolic tolerance.

Dietary glutamine supplementation reduces cellular adhesion molecule expression and tissue myeloperoxidase activity in mice with gut-derived sepsis

OBJECTIVES

This study investigated the effects of glutamine (Gln) on plasma intracellular adhesion molecule-1 levels and leukocyte integrin (CD11a/CD18 and CD11b/CD18) expressions in gut-derived sepsis. Myeloperoxidase (MPO) activities in organs were also analyzed to identify the extent of tissue injury resulting from neutrophil infiltration.

METHODS

Mice were randomly assigned to a normal group (NC), a control group, or a Gln group. The NC group was fed standard chow diet; the control group was fed a common semipurified diet; and the Gln group received a diet in which part of the casein was replaced by Gln, which provided 25% of total amino acid nitrogen. After 3 wk, sepsis was induced by cecal ligation and puncture (CLP) in the control and Gln groups. Mice in the experimental groups were killed at 0, 6, 12, and 24 h after CLP. Mice in the NC group were killed when CLP was performed. Blood and organ samples were collected for further analysis.

RESULTS

Plasma intracellular adhesion molecule-1 levels were significantly lower in the Gln group than in the control group at 6, 12, and 24 h after CLP. Expressions of lymphocyte CD11a/CD18 were significantly higher, whereas polymorphonuclear lymphocyte expressions of CD11b/CD18 were lower in the Gln group than in the corresponding control group at 6 and 12 h after CLP. In comparisons of MPO activities in various organs, the Gln group had lower MPO activities at 6 and 12 h in the lung, at 6, 12, and 24 h in the liver, at 12 and 24 h in the kidneys, and at 12 h in the intestine than those in the control group.

CONCLUSIONS

Results of this study demonstrate that a Gln-supplemented enteral diet increased lymphocyte CD11a/CD18 expressions, whereas neutrophil CD11b/CD18 expressions, circulating intracellular adhesion molecule-1 levels, and MPO activities in various organs decreased with gut-derived sepsis. These findings suggest that, under septic conditions, Gln administration may enhance lymphocyte function, attenuate interactions between polymorphonuclear lymphocytes and endothelium, and thus may decrease neutrophil infiltration into tissues.

Effects of glutamine supplementation on splenocyte cytokine mRNA expression in rats with septic peritonitis

AIM: To investigate the effects of glutamine (GLN)-enriched diets before and GLN-containing total parenteral nutrition (TPN) after sepsis or both on the secretion of cytokines and their mRNA expression levels in splenocytes of rats with septic peritonitis.

METHODS: Rats were assigned to a control group and 4 experimental groups. The control group and experimental groups 1 and 2 were fed a semipurified diet, while experimental groups 3 and 4 had part of the casein replaced by GLN which provided 25% of the total nitrogen. After rats were fed with these diets for 10 d, sepsis was induced by cecal ligation and puncture (CLP), whereas the control group underwent a sham operation, at the same time, an internal jugular vein was cannulated. All rats were maintained on TPN for 3 d. The control group and experimental groups 1 and 3 were infused with conventional TPN, while the TPN in experimental groups 2 and 4 was supplemented with GLN, providing 25% of the total nitrogen in the TPN solution. All rats were kiued 3 d after sham operation or CLP to examine their splenocyte subpopulation distribution and cytokine expression levels.

RESULTS: Most cytokines could not be detected in plasma except for IL-10. No difference in plasma IL-10 was observed among the 5 groups. The IL-2, IL-4, IL-10, and TNF-α mRNA expression levels in splenocytes were significantly higher in experimental groups 2 and 4 than in the control group and group 1. The mRNA expression of IFN-γ was significantly higher in the GLN-supplemented groups than in the control group and experimental group 1. The proportion of CD45Ra+ was increased, while those of CD3+ and CD4+ were decreased in experimental group 1 after CLP was performed. There were no differences in spleen CD3+ lymphocyte distributions between the control and GLN-supplemented groups.

CONCLUSION: GLN supplementation can maintain T-lymphocyte populations in the spleen and significantly enhance the mRNA expression levels of Th1 and Th2 cytokines and TNF-α in the spleen of rats with septic peritonitis.