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[This corrects the article DOI: 10.1371/journal.pone.0203552.].[This corrects the article DOI: 10.1371/journal.pone.0203552.].

Glutamine is thought to have beneficial effects on the metabolic and stress response to severe injury. Clinical trials involving patients with burns and other critically ill patients have shown conflicting results regarding the benefits and risks of glutamine supplementation. In a double-blind, randomized, placebo-controlled trial, we assigned patients with deep second- or third-degree burns (affecting ≥10% to ≥20% of total body-surface area, depending on age) within 72 hours after hospital admission to receive 0.5 g per kilogram of body weight per day of enterally delivered glutamine or placebo. Trial agents were given every 4 hours through a feeding tube or three or four times a day by mouth until 7 days after the last skin grafting procedure, discharge from the acute care unit, or 3 months after admission, whichever came first. The primary outcome was the time to discharge alive from the hospital, with data censored at 90 days. We calculated subdistribution hazard ratios for discharge alive, which took into account death as a competing risk. A total of 1209 patients with severe burns (mean burn size, 33% of total body-surface area) underwent randomization, and 1200 were included in the analysis (596 patients in the glutamine group and 604 in the placebo group). The median time to discharge alive from the hospital was 40 days (interquartile range, 24 to 87) in the glutamine group and 38 days (interquartile range, 22 to 75) in the placebo group (subdistribution hazard ratio for discharge alive, 0.91; 95% confidence interval [CI], 0.80 to 1.04; P = 0.17). Mortality at 6 months was 17.2% in the glutamine group and 16.2% in the placebo group (hazard ratio for death, 1.06; 95% CI, 0.80 to 1.41). No substantial between-group differences in serious adverse events were observed. In patients with severe burns, supplemental glutamine did not reduce the time to discharge alive from the hospital. (Funded by the U.S. Department of Defense and the Canadian Institutes of Health Research; RE-ENERGIZE ClinicalTrials.gov number, NCT00985205.).

A year-long, phase 3, randomized trial involving patients with sickle cell disease showed that the median number of pain crises was 25% lower and the median number of hospitalizations was 33% lower with l -glutamine supplementation than with placebo.

This trial involving critically ill adults with multiorgan failure who were receiving mechanical ventilation showed that early provision of glutamine and antioxidants did not improve clinical outcomes. Furthermore, the use of glutamine appeared to increase mortality. Critically ill patients have oxidative stress. The most seriously ill patients in intensive care units (ICUs) have increased mediators of oxidant stress and a higher incidence of multiorgan failure than less seriously ill patients. 1 – 5 Meta-analyses of randomized trials suggest that glutamine and antioxidant supplementation in critically ill patients may be associated with improved survival. 6 , 7 However, recent large studies have not confirmed such an effect. 8 , 9 The objective of the present trial was to evaluate the effect of early glutamine and antioxidant supplementation in critically ill patients. Our a priori hypothesis was that supplementation with these nutrients would reduce . . .

Glutamine is an essential cerebral metabolite. Several critical brain processes are directly linked to glutamine, including ammonia homeostasis, energy metabolism and neurotransmitter recycling. Astrocytes synthesize and release large quantities of glutamine, which is taken up by neurons to replenish the glutamate and GABA neurotransmitter pools. Astrocyte glutamine hereby sustains the glutamate/GABA-glutamine cycle, synaptic transmission and general brain function. Cerebral glutamine homeostasis is linked to the metabolic coupling of neurons and astrocytes, and relies on multiple cellular processes, including TCA cycle function, synaptic transmission and neurotransmitter uptake. Dysregulations of processes related to glutamine homeostasis are associated with several neurological diseases and may mediate excitotoxicity and neurodegeneration. In particular, diminished astrocyte glutamine synthesis is a common neuropathological component, depriving neurons of an essential metabolic substrate and precursor for neurotransmitter synthesis, hereby leading to synaptic dysfunction. While astrocyte glutamine synthesis is quantitatively dominant in the brain, oligodendrocyte-derived glutamine may serve important functions in white matter structures. In this review, the crucial roles of glial glutamine homeostasis in the healthy and diseased brain are discussed. First, we provide an overview of cellular recycling, transport, synthesis and metabolism of glutamine in the brain. These cellular aspects are subsequently discussed in relation to pathological glutamine homeostasis of hepatic encephalopathy, epilepsy, Alzheimer’s disease, Huntington’s disease and amyotrophic lateral sclerosis. Further studies on the multifaceted roles of cerebral glutamine will not only increase our understanding of the metabolic collaboration between brain cells, but may also aid to reveal much needed therapeutic targets of several neurological pathologies.

Rapidly proliferating tumor and immune cells need metabolic programs that support energy and biomass production. The amino acid glutamine is consumed by effector T cells and glutamine-addicted triple-negative breast cancer (TNBC) cells, suggesting that a metabolic competition for glutamine may exist within the tumor microenvironment, potentially serving as a therapeutic intervention strategy. Here, we report that there is an inverse correlation between glutamine metabolic genes and markers of T cell-mediated cytotoxicity in human basal-like breast cancer (BLBC) patient data sets, with increased glutamine metabolism and decreased T cell cytotoxicity associated with poor survival. We found that tumor cell-specific loss of glutaminase (GLS), a key enzyme for glutamine metabolism, improved antitumor T cell activation in both a spontaneous mouse TNBC model and orthotopic grafts. The glutamine transporter inhibitor V-9302 selectively blocked glutamine uptake by TNBC cells but not CD8+ T cells, driving synthesis of glutathione, a major cellular antioxidant, to improve CD8+ T cell effector function. We propose a \"glutamine steal\" scenario, in which cancer cells deprive tumor-infiltrating lymphocytes of needed glutamine, thus impairing antitumor immune responses. Therefore, tumor-selective targeting of glutamine metabolism may be a promising therapeutic strategy in TNBC.

Einleitung: Mittels Protonenspektroskopie konnte gezeigt werden, dass N-Acetylaspartat (NAA), Creatin (Cr) und Glutamat & Glutamin (Glx) mit spezifischen Veranderungen des Transskriptoms bei Glioblastomen (GBM) vergesellschaftet sind (Heiland DH et al. Sci Rep 2016). So war NAA mit einer oligodendrozytaren Differenzierung, Cr mit der proneuralen und Glx mit der klassischen subgruppe des GBM assoziiert. Ziel dieser studie war es, anhand von hochaufgelosten invitro spektren die Zusammenhange zwischen Metaboliten der Protonenspektroskopie und dem Tumorgenom genauer zu beschreiben. Material und Methoden: Navigations-basiert wurden Proben aus dem Kontrastmittel-aufnehmenden Anteil von 33 GBM entnommen und mittels hochaufgeloster 1D NMR spektroskopie analysiert bei 14.1 T (600 MHz, Bruker), Abb. 1A. Eine Genom-weite Expressionsanalyse erfolgte mittels eines Genchips (ST2.0, Affymetrix) und eine Einteilung in die subgruppen nach Verhaak. Eine Netzwerkanalyse (WGC-NA) identifizierte zusammenhangende Gen- und Metaboliten-Module. Ergebnisse: Vier Gentranskriptom-subgruppen konnten identifiziert werden: Oligodendrozytare Differenzierung (schlusselmetabolit creatin) und Zellzyklus (Glycin), beide proneural, sowie Immunantwort (cholin), und Hypoxie (Laktat), beide mesenchymal. Diskussion: Auch in der Literatur sind die o. g. vier transkriptomsubgruppen anhand von genetischen Einzelzell-Analysen eines GBM beschrieben (Patel AP, et al. science 2014). Die Zuordnung von Einzelmetaboliten zu diesen subgruppen ist neu. Der stoffwechselweg (KEGG Pathway Database) zeigt, dass in Anwesenheit von cr ein Weg mit proneural aktivierten Genen uber Guanidinoacetat beschritten wird, wohingegegen uber Glycin der mesenchymale Weg zum Laktat geht, Abb. 1B.

Chemical modifications of histones can mediate diverse DNA-templated processes, including gene transcription 1 – 3 . Here we provide evidence for a class of histone post-translational modification, serotonylation of glutamine, which occurs at position 5 (Q5ser) on histone H3 in organisms that produce serotonin (also known as 5-hydroxytryptamine (5-HT)). We demonstrate that tissue transglutaminase 2 can serotonylate histone H3 tri-methylated lysine 4 (H3K4me3)-marked nucleosomes, resulting in the presence of combinatorial H3K4me3Q5ser in vivo. H3K4me3Q5ser displays a ubiquitous pattern of tissue expression in mammals, with enrichment observed in brain and gut, two organ systems responsible for the bulk of 5-HT production. Genome-wide analyses of human serotonergic neurons, developing mouse brain and cultured serotonergic cells indicate that H3K4me3Q5ser nucleosomes are enriched in euchromatin, are sensitive to cellular differentiation and correlate with permissive gene expression, phenomena that are linked to the potentiation of TFIID 4 – 6 interactions with H3K4me3. Cells that ectopically express a H3 mutant that cannot be serotonylated display significantly altered expression of H3K4me3Q5ser-target loci, which leads to deficits in differentiation. Taken together, these data identify a direct role for 5-HT, independent from its contributions to neurotransmission and cellular signalling, in the mediation of permissive gene expression. In serotonin-rich tissues, tissue transglutaminase 2 is able to attach serotonin to a glutamine residue in histone H3; this modification mediates permissive gene expression in these tissues.

Purpose To examine the dose–response effects of acute glutamine supplementation on markers of gastrointestinal (GI) permeability, damage and, secondary, subjective symptoms of GI discomfort in response to running in the heat. Methods Ten recreationally active males completed a total of four exercise trials; a placebo trial and three glutamine trials at 0.25, 0.5 and 0.9 g kg −1 of fat-free mass (FFM) consumed 2 h before exercise. Each exercise trial consisted of a 60-min treadmill run at 70% of V ˙ O 2max in an environmental chamber set at 30 °C. GI permeability was measured using ratio of lactulose to rhamnose (L:R) in serum. Plasma glutamine and intestinal fatty acid binding protein (I-FABP) concentrations were determined pre and post exercise. Subjective GI symptoms were assessed 45 min and 24 h post-exercise. Results Relative to placebo, L:R was likely lower following 0.25 g kg −1 (mean difference: − 0.023; ± 0.021) and 0.5 g kg −1 (− 0.019; ± 0.019) and very likely following 0.9 g kg − 1 (− 0.034; ± 0.024). GI symptoms were typically low and there was no effect of supplementation. Discussion Acute oral glutamine consumption attenuates GI permeability relative to placebo even at lower doses of 0.25 g kg −1 , although larger doses may be more effective. It remains unclear if this will lead to reductions in GI symptoms. Athletes competing in the heat may, therefore, benefit from acute glutamine supplementation prior to exercise in order to maintain gastrointestinal integrity.