Glutamine reduces cytokine release, organ damage, and mortality in a rat model of endotoxemia

Bay-117082 treats sepsis by inhibiting neutrophil extracellular traps (NETs) formation through down-regulating NLRP3/N-GSDMD

During the inflammatory storm of sepsis, a significant quantity of neutrophil extracellular traps (NETs) are generated, which act as a double-edged sword and not only impede the invasion of foreign microorganisms but also exacerbate organ damage. This study provides evidence that NETs can cause damage to alveolar epithelial cells in vitro. The sepsis model developed in this study showed a significant increase in NETs in the bronchoalveolar lavage fluid (BALF). The development of NETs has been shown to increase the lung inflammatory response and aggravate injury to alveolar epithelial cells. Bay-117082, a well-known NF-κB suppressor, is used to modulate inflammation. This analysis revealed that Bay-117082 efficiently reduced total protein concentration, myeloperoxidase activity, and inflammatory cytokines in BALF. Moreover, Bay-117082 inhibited the formation of NETs, which in turn prevented the activation of the pore-forming protein gasdermin D (GSDMD). In summary, these results indicated that excessive NET production during sepsis exacerbated the onset and progression of acute lung injury (ALI). Therefore, Bay-117082 could serve as a novel therapeutic approach for ameliorating sepsis-associated ALI.

The Role of Glutamine Homeostasis in Emotional and Cognitive Functions

Glutamine (Gln), a non-essential amino acid, is synthesized de novo by glutamine synthetase (GS) in various organs. In the brain, GS is exclusively expressed in astrocytes under normal physiological conditions, producing Gln that takes part in glutamatergic neurotransmission through the glutamate (Glu)-Gln cycle. Because the Glu-Gln cycle and glutamatergic neurotransmission play a pivotal role in normal brain activity, maintaining Gln homeostasis in the brain is crucial. Recent findings indicated that a neuronal Gln deficiency in the medial prefrontal cortex in rodents led to depressive behaviors and mild cognitive impairment along with lower glutamatergic neurotransmission. In addition, exogenous Gln supplementation has been tested for its ability to overcome neuronal Gln deficiency and reverse abnormal behaviors induced by chronic immobilization stress (CIS). Although evidence is accumulating as to how Gln supplementation contributes to normalizing glutamatergic neurotransmission and the Glu-Gln cycle, there are few reviews on this. In this review, we summarize recent evidence demonstrating that Gln supplementation ameliorates CIS-induced deleterious changes, including an imbalance of the Glu-Gln cycle, suggesting that Gln homeostasis is important for emotional and cognitive functions. This is the first review of detailed mechanistic studies on the effects of Gln supplementation on emotional and cognitive functions.

From genes to systems: The role of food supplementation in the regulation of sepsis-induced inflammation

Systemic inflammation includes a widespread immune response to a harmful stimulus that results in extensive systemic damage. One common example of systemic inflammation is sepsis, which is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. Under the pro-inflammatory environment of sepsis, oxidative stress contributes to tissue damage due to dysfunctional microcirculation that progressively causes the failure of multiple organs that ultimately triggers death. To address the underlying inflammatory condition in critically ill patients, progress has been made to assess the beneficial effects of dietary supplements, which include polyphenols, amino acids, fatty acids, vitamins, and minerals that are recognized for their immuno-modulating, anticoagulating, and analgesic properties. Therefore, we aimed to review and discuss the contribution of food-derived supplementation in the regulation of inflammation from gene expression to physiological responses and summarize the precedented potential of current therapeutic approaches during systemic inflammation.

Untargeted metabolomic analysis investigating links between unprocessed red meat intake and markers of inflammation

BACKGROUND

Whether red meat consumption is associated with higher inflammation or confounded by increased adiposity remains unclear. Plasma metabolites capture the effects of diet after food is processed, digested, and absorbed, and correlate with markers of inflammation, so they can help clarify diet-health relationships.

OBJECTIVE

To identify whether any metabolites associated with red meat intake are also associated with inflammation.

METHODS

A cross-sectional analysis of observational data from older adults (52.84% women, mean age 63 ± 0.3 y) participating in the Multi-Ethnic Study of Atherosclerosis (MESA). Dietary intake was assessed by food-frequency questionnaire, alongside C-reactive protein (CRP), interleukin-2, interleukin-6, fibrinogen, homocysteine, and tumor necrosis factor alpha, and untargeted proton nuclear magnetic resonance (1H NMR) metabolomic features. Associations between these variables were examined using linear regression models, adjusted for demographic factors, lifestyle behaviors, and body mass index (BMI).

RESULTS

In analyses that adjust for BMI, neither processed nor unprocessed forms of red meat were associated with any markers of inflammation (all P > 0.01). However, when adjusting for BMI, unprocessed red meat was inversely associated with spectral features representing the metabolite glutamine (sentinel hit: β = -0.09 ± 0.02, P = 2.0 × 10-5), an amino acid which was also inversely associated with CRP level (β = -0.11 ± 0.01, P = 3.3 × 10-10).

CONCLUSIONS

Our analyses were unable to support a relationship between either processed or unprocessed red meat and inflammation, over and above any confounding by BMI. Glutamine, a plasma correlate of lower unprocessed red meat intake, was associated with lower CRP levels. The differences in diet-inflammation associations, compared with diet metabolite-inflammation associations, warrant further investigation to understand the extent that these arise from the following: 1) a reduction in measurement error with metabolite measures; 2) the extent that which factors other than unprocessed red meat intake contribute to glutamine levels; and 3) the ability of plasma metabolites to capture individual differences in how food intake is metabolized.

Alanyl-Glutamine (Ala-Gln) Ameliorates Dextran Sulfate Sodium (DSS)-Induced Acute Colitis by Regulating the Gut Microbiota, PI3K-Akt/NF-κB/STAT3 Signaling, and Associated Pulmonary Injury

The aim of this study was to investigate the protective effect of alanyl-glutamine (Ala-Gln) on acute colitis complicated by pulmonary injury induced by dextran sulfate sodium (DSS) in C57BL/6 mice. The results showed that Ala-Gln intervention alleviated weight loss, the disease activity index (DAI), colon shortening, and pathological injury and regulated the absolute number of CD4⁺T-cell subsets in mesenteric lymph nodes (MLNs). In addition, Ala-Gln intervention significantly ameliorated the composition of the gut microbiota in mice with DSS- induced acute colitis, significantly decreasing the relative abundance of Desulfovibrionaceae and increasing the abundances of Gastranaerophilales, Clostridia-vadinBB60, and Alistipes. Moreover, Ala-Gln treatment significantly inhibited the activation of the PI3K-Akt/NF-κB/STAT3 inflammatory signaling pathways in the colon of mice with DSS-induced acute colitis. Notably, Ala-Gln intervention also alleviated the pulmonary injury as well as the imbalance in levels of CD4⁺T-cell subsets in pulmonary tissue in mice with DSS-induced acute colitis. In conclusion, Ala-Gln alleviates DSS-induced acute colitis by regulating the gut microflora and PI3K-Akt/NF-κB/STAT3 signaling pathways, as well as by alleviating accompanying pulmonary injury.

The Possible Importance of Glutamine Supplementation to Mood and Cognition in Hypoxia from High Altitude

Hypoxia induced by low O₂ pressure is responsible for several physiological and behavioral alterations. Changes in physiological systems are frequent, including inflammation and psychobiological declines such as mood and cognition worsening, resulting in increased reaction time, difficulty solving problems, reduced memory and concentration. The paper discusses the possible relationship between glutamine supplementation and worsening cognition mediated by inflammation induced by high altitude hypoxia. The paper is a narrative literature review conducted to verify the effects of glutamine supplementation on psychobiological aspects. We searched MEDLINE/PubMed and Web of Science databases and gray literature by Google Scholar for English articles. Mechanistic pathways mediated by glutamine suggest potential positive effects of its supplementation on mood and cognition, mainly its potential effect on inflammation. However, clinical studies are scarce, making any conclusions impossible. Although glutamine plays an important role and seems to mitigate inflammation, clinical studies should test this hypothesis, which will contribute to a better mood and cognition state for several people who suffer from problems mediated by hypoxia.

Pharmaconutrition in the Clinical Management of COVID-19: A Lack of Evidence-Based Research But Clues to Personalized Prescription

A scientific interest has emerged to identify pharmaceutical and nutritional strategies in the clinical management of coronavirus disease 2019 (COVID-19). The purpose of this narrative review is to critically assess and discuss pharmaconutrition strategies that, secondary to accepted treatment methods, could be candidates in the current context of COVID-19. Oral medicinal doses of vitamin C (1-3 g/d) and zinc (80 mg/d elemental zinc) could be promising at the first signs and symptoms of COVID-19 as well as for general colds. In critical care situations requiring parenteral nutrition, vitamin C (3-10 g/d) and glutamine (0.3-0.5 g/kg/d) administration could be considered, whereas vitamin D3 administration (100,000 IU administered intramuscularly as a one-time dose) could possess benefits for patients with severe deficiency. Considering the presence of n-3 polyunsaturated fatty acids and arginine in immune-enhancing diets, their co-administration may also occur in clinical conditions where these formulations are recommended. However, despite the use of the aforementioned strategies in prior contexts, there is currently no evidence of the utility of any nutritional strategies in the management of SARS-CoV-2 infection and COVID-19. Nevertheless, ongoing and future clinical research is imperative to determine if any pharmaconutrition strategies can halt the progression of COVID-19.

Antecedent Dietary Glutamine Supplementation Benefits Modulation of Liver Pyroptosis in Mice with Polymicrobial Sepsis

The liver is the main organ responsible for bacterial and endotoxin clearance. Pyroptosis is a form of proinflammatory programmed cell death activated by caspase-1/11 and gasdermin D (GadD). Pyroptosis protects the host against bacterial infection; however, overactive pyroptosis can lead to organ injury. Glutamine (GLN) is a specific amino acid with anti-inflammatory and immunomodulatory properties. This study investigated the effects of GLN pretreatment on liver pyroptosis in a mouse model of polymicrobial sepsis. Mice were assigned to sham, sepsis control (Sepsis-C), and sepsis GLN (Sepsis-G) groups. The sham and Sepsis-C groups were fed the AIN-93G diet. The Sepsis-G group was provided with identical diet components except that part of the casein was replaced by GLN. After feeding the respective diets for 2 weeks, a cecal ligation and puncture (CLP) procedure was performed in the sepsis groups. An antibiotic was administered after CLP. Mice were sacrificed at either 24 or 72 h after CLP. The results showed that sepsis resulted in upregulated liver caspase-1/11 expression. Compared to the Sepsis-C group, the Sepsis-G group had higher liver caspase-11 and NLRP3 gene expressions at 24 h and lower active caspase-1/11 and cleaved GadD protein levels at 72 h after sepsis. Additionally, liver inflammatory cytokine gene expressions had decreased by 72 h post-CLP. The findings suggest that prophylactic administration of GLN initially upregulated liver pyroptosis to eradicate pathogens, yet the process of pyroptosis was suppressed in the late phase of sepsis. This may have beneficially attenuated liver inflammation and injury in an antibiotic-treated septic condition.

Glutamine supports the protection of tissue cells against the damage caused by cholesterol-dependent cytolysins from pathogenic bacteria

Pathogenic bacteria often damage tissues by secreting toxins that form pores in cell membranes, and the most common pore-forming toxins are cholesterol-dependent cytolysins. During bacterial infections, glutamine becomes a conditionally essential amino acid, and glutamine is an important nutrient for immune cells. However, the role of glutamine in protecting tissue cells against pore-forming toxins is unclear. Here we tested the hypothesis that glutamine supports the protection of tissue cells against the damage caused by cholesterol-dependent cytolysins. Stromal and epithelial cells were sensitive to damage by the cholesterol-dependent cytolysins, pyolysin and streptolysin O, as determined by leakage of potassium and lactate dehydrogenase from cells, and reduced cell viability. However, glutamine deprivation increased the leakage of lactate dehydrogenase and reduced the viability of cells challenged with cholesterol-dependent cytolysins. Without glutamine, stromal cells challenged with pyolysin leaked lactate dehydrogenase (control vs. pyolysin, 2.6 ± 0.6 vs. 34.4 ± 4.5 AU, n = 12), which was more than three-fold the leakage from cells supplied with 2 mM glutamine (control vs. pyolysin, 2.2 ± 0.3 vs. 9.4 ± 1.0 AU). Glutamine cytoprotection did not depend on glutaminolysis, replenishing the Krebs cycle via succinate, changes in cellular cholesterol, or regulators of cell metabolism (AMPK and mTOR). In conclusion, although the mechanism remains elusive, we found that glutamine supports the protection of tissue cells against the damage caused by cholesterol-dependent cytolysins from pathogenic bacteria.

Akt activation by insulin treatment attenuates cachexia in Walker-256 tumor-bearing rats

Cancer-bearing often exhibits hypoinsulinemia, insulin (INS) resistance and glutamine depletion associated with cachexia. However, INS and glutamine effects on cachexia metabolic abnormalities, particularly on tumor-affected proteins related to INS resistance, are poorly known. The main purpose of this study was to investigate the effects of INS and glutamine dipeptide (GDP) treatments on phospho-protein kinase B (p-Akt), and phospho-hormone sensitive lipase (p-HSL) in Walker-256 tumor-bearing rats. INS (NPH, 40 UI/kg, subcutaneous), GDP (1.5 g/kg, oral), INS+GDP or vehicle (control rats) were administered for 13 days, once a day, starting at the day of inoculation of tumor cells. The experiments were performed 4 hours after the last treatment to evaluate acute effects of INS and GDP, besides the chronic effects. INS and/or INS+GDP treatments, which markedly increased the insulinemia, increased the p-Akt: total Akt ratio and prevented the increased p-HSL^Ser552 : total HSL ratio in the retroperitoneal fat of tumor-bearing rats, without changing the INS resistance and increased expression of factor tumor necrosis-α (TNF-α) in this tissue. INS and INS+GDP also increased the p-Akt: total Akt ratio, whereas GDP and INS+GDP increased the GLUT4 glucose transporter gene expression, in the gastrocnemius muscle of the tumor-bearing rats. Accordingly, treatments with INS and INS+GDP markedly reduced glycemia, increased retroperitoneal fat and attenuated the body mass loss of tumor-bearing rats. In conclusion, hyperinsulinemia induced by high-dose INS treatments increased Akt phosphorylation and prevented increased p-HSL^Ser552 : total HSL ratio, overlapping INS resistance. These effects are consistent with increased fat mass gain and weight loss (cachexia) attenuation of tumor-bearing rats, evidencing that Akt activation is a potential strategy to prevent loss of fat mass in cancer cachexia.

Anti-Inflammatory Activities of Isogosferol, a Furanocoumarin Isolated from Citrus junos Seed Shells through Bioactivity-Guided Fractionation

Citrus junos Tanaka is a traditional medicine for treating coughs, dyspepsia, diabetes, asthma, neuralgia, and inflammatory disorders, and is distributed in Asia, especially in Korea, Japan, and China. This study aimed to use bioactivity-guided fractionation to find therapeutic phytochemicals from C. junos seeds, which can attenuate inflammatory responses. Nine coumarins (1-9) were isolated from the methanolic extract of C. junos seed shells and the inhibitory effects against inflammatory mediators were investigated using murine macrophages. Among the coumarins, compound 3, isogosferol (ISO), more potently attenuated the production of nitric oxide (NO) in lipopolysaccharide (LPS)-induced RAW 264.7 cells. ISO also inhibited the expression of inducible nitric oxide (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated macrophages. Additionally, the phosphorylation of extracellular-regulated kinases (pERK)1/2 was reduced by ISO. We confirmed that ISO attenuated the release of interleukin-1 beta (IL-1β), which is a central mediator of the inflammatory response. These results demonstrate that ISO from C. junos seed shells may be a potent therapeutic candidate for the treatment of inflammatory diseases.

Glutamine in Burn Injury

Burn injury is the most devastating of survivable injuries and is a worldwide public health crisis. Burn injury is among the most severe metabolic stresses a patient can sustain. A major burn leads to an inflammatory response and catabolism that, when compounded by burn wound nutrient losses, can lead to severe nutrition losses and deficiencies. These losses can impair immune function and wound healing and place burn patients at high risk for organ injury and mortality. Experimental data indicate glutamine (GLN) is well positioned mechanistically, perhaps above and beyond in any other intensive care unit setting, to improve outcome in burn-injured patients. Initial clinical trial data have also shown a consistent signal of reduced mortality and reduced hospital length of stay in burn-injured subjects, without signals of clinical risk. A number of GLN clinical trials demonstrate significant reductions of gram-negative bacteremia in burn injury, perhaps via maintenance of the gut barrier or gut immune function. Current societal recommendations continue to suggest the use of GLN in burn injury. The promising clinical data in burn-injured patients, with no signals of harm, have warranted study of GLN in the definitive RE-ENERGIZE trial, which is now ongoing.

Effects of oral supplementation in the management of oral mucositis in cancer patients: A meta-analysis of randomized clinical trials

PURPOSE

To evaluate the effects of oral supplementation on the management of oral mucositis in patients with cancer undergoing chemo and/or radiation therapy.

METHOD

This is a systematic review and meta-analysis. The search was performed at 6 databases, and in the gray literature. Methodology of included studies was evaluated by the Cochrane Collaboration Risk of Bias Tool, and evidence quality was assessed by GRADE instrument.

RESULTS

Twelve randomized clinical trials were included in this review. The oral supplementation used was an oral elemental diet with amino acids and minerals (elental), glutamine, and zinc. The majority of the studies included in this review showed benefits in delaying the occurrence of OM by using glutamine and zinc, and in reducing the severity of OM with glutamine, zinc, and elental in patients receiving chemoradiotherapy. The meta-analysis showed that the risk of oral mucositis in the zinc group was slightly lower than in the control (RR: 0.71, 95% CI: 0.53-0.96, P = 0.02, n = 982) while the glutamine group presented the same risk as the control (RR: 0.91, 95% CI: 0.78-1.05, P = 0.19, n = 314). The evidence quality suggested low confidence for zinc and glutamine studies in the estimated effect from the outcomes assessed.

CONCLUSIONS

Zinc is a promising strategy in the management of oral mucositis since it delayed the occurrence and reduced its severity. Glutamine and Elental, on the other hand, had no strong evidence in the prevention and/or treatment of oral mucositis in patients with cancer.

Glutamine Ameliorates Mucosal Damage Caused by Immune Responses to Duck Plague Virus

The immune-releasing effects of L-glutamine (Gln) supplementation in duck plague virus (DPV)-infected ducklings were evaluated in 120 seven-day-old ducklings that were divided into 8 groups. The ducklings in control and DPV, 0.5Gln and DPV + 0.5Gln, 1.0Gln and DPV + 1.0Gln, and 2.0Gln and DPV + 2.0Gln received 0, 0.5, 1.0, and 2.0 g of Gln/kg feed/d by gastric perfusion, respectively. Then, the ducklings in control to 2.0Gln were injected with 0.2 mL of phosphate-buffered saline, while those in DPV to DPV + 2.0Gln were injected with DPV at 0.2 mL of 2000 TCID₅₀ (50% tissue culture infection dose) 30 minutes after gavage with Gln, sampled at 12 hours and days 1, 2, 4, and 6. Glutamine supplementation under physiological conditions enhanced immune function and toll-like receptor 4 (TLR4) expressions in a dose-dependent manner. An increase in Gln supplementation under DPV-infected conditions enhanced growth performance, decreased immunoglobulin (Ig) release in plasma and secretory IgA in the duodenum, ameliorated plasma cytokine levels, and suppressed overexpressions of the TLR4 pathway in the duodenum. The positive effects of Gln on the humoral immunity- and intestinal inflammation-related damage should be considered a mechanism by which immunonutrition can assist in the recovery from DPV infection.

Effect of Amino Acid Infusion on Human Postoperative Colon Protein Synthesisin Situ

BACKGROUND

Amino acids are an integral part of parenteral nutrition because of their anabolic action helping to conserve body protein after surgical stress. At the gastrointestinal tract, an adequate supply of amino acids may be particularly important because of the gut's high rate of protein turnover, cell division, and proliferation. However, no information is available about the effects of amino acids on human intestinal protein metabolism after surgery.

METHODS

Studies were performed in postabsorptive patients 8-10 days after major abdominal surgery. Mass spectrometry techniques (capillary gas chromatography/combustion isotope ratio mass spectrometry) were used to directly determine the incorporation rate of 1-[13C]-leucine into colon mucosal protein. All subjects had a colostomy, which allowed easy access to the colon mucosa, and consecutive sampling from the same tissue was performed during continuous isotope infusion (0.16 micromol/kg min). Isotopic enrichments were determined at baseline and after a 4-hour infusion of amino acids or after infusion of saline (control group).

RESULTS

Compared with baseline, infusion of amino acids reduced fractional colon protein synthesis significantly by -29.2 +/- 8.3%. This decrease was also significantly different from the corresponding (insignificant) change during saline infusion (+19.4 +/- 26.9%, p < .05 vs amino acid group).

CONCLUSIONS

After surgery, an amino acid infusion acutely reduces postoperative colon protein synthesis. This effect possibly may be attributed to interactions of specific amino acids (glutamine) with an altered intestinal immune system and enterocyte activity.

Efficacy and Safety of Glutamine-supplemented Parenteral Nutrition in Surgical ICU Patients: An American Multicenter Randomized Controlled Trial

OBJECTIVE

To determine whether glutamine (GLN)-supplemented parenteral nutrition (PN) improves clinical outcomes in surgical intensive care unit (SICU) patients.

SUMMARY BACKGROUND DATA

GLN requirements may increase with critical illness. GLN-supplemented PN may improve clinical outcomes in SICU patients.

METHODS

A parallel-group, multicenter, double-blind, randomized, controlled clinical trial in 150 adults after gastrointestinal, vascular, or cardiac surgery requiring PN and SICU care. Patients were without significant renal or hepatic failure or shock at entry. All received isonitrogenous, isocaloric PN [1.5 g/kg/d amino acids (AAs) and energy at 1.3× estimated basal energy expenditure]. Controls (n = 75) received standard GLN-free PN (STD-PN); the GLN group (n = 75) received PN containing alanyl-GLN dipeptide (0.5 g/kg/d), proportionally replacing AA in PN (GLN-PN). Enteral nutrition (EN) was advanced and PN weaned as indicated. Hospital mortality and infections were primary endpoints.

RESULTS

Baseline characteristics, days on study PN and daily macronutrient intakes via PN and EN, were similar between groups. There were 11 hospital deaths (14.7%) in the GLN-PN group and 13 deaths in the STD-PN group (17.3%; difference, -2.6%; 95% confidence interval, -14.6% to 9.3%; P = 0.66). The 6-month cumulative mortality was 31.4% in the GLN-PN group and 29.7% in the STD-PN group (P = 0.88). Incident bloodstream infection rate was 9.6 and 8.4 per 1000 hospital days in the GLN-PN and STD-PN groups, respectively (P = 0.73). Other clinical outcomes and adverse events were similar.

CONCLUSIONS

PN supplemented with GLN dipeptide was safe, but did not alter clinical outcomes among SICU patients.

Neuromuscular Dysfunction in Experimental Sepsis and Glutamine

BACKGROUND

Electrophysiological studies show that critical illness polyneuromyopathy appears in the early stage of sepsis before the manifestation of clinical findings. The metabolic response observed during sepsis causes glutamine to become a relative essential amino acid.

AIMS

We aimed to assess the changes in neuromuscular transmission in the early stage of sepsis after glutamine supplementation.

STUDY DESIGN

Animal experimentation.

METHODS

Twenty male Sprague-Dawley rats were randomized into two groups. Rats in both groups were given normal feeding for one week. In the study group, 1 g/kg/day glutamine was added to normal feeding by feeding tube for one week. Cecal ligation and perforation (CLP) surgery was performed at the end of one week. Before and 24 hours after CLP, compound muscle action potentials were recorded from the gastrocnemius muscle.

RESULTS

Latency measurements before and 24 hours after CLP were 0.68±0.05 ms and 0.80±0.09 ms in the control group and 0.69±0.07 ms and 0.73±0.07 ms in the study group (p<0.05).

CONCLUSION

Since enteral glutamine prevented compound muscle action potentials (CMAP) latency prolongation in the early phase of sepsis, it was concluded that enteral glutamine replacement might be promising in the prevention of neuromuscular dysfunction in sepsis; however, further studies are required.

CD1d- and MR1-Restricted T Cells in Sepsis

Dysregulated immune responses to infection, such as those encountered in sepsis, can be catastrophic. Sepsis is typically triggered by an overwhelming systemic response to an infectious agent(s) and is associated with high morbidity and mortality even under optimal critical care. Recent studies have implicated unconventional, innate-like T lymphocytes, including CD1d- and MR1-restricted T cells as effectors and/or regulators of inflammatory responses during sepsis. These cell types are typified by invariant natural killer T (iNKT) cells, variant NKT (vNKT) cells, and mucosa-associated invariant T (MAIT) cells. iNKT and vNKT cells are CD1d-restricted, lipid-reactive cells with remarkable immunoregulatory properties. MAIT cells participate in antimicrobial defense, and are restricted by major histocompatibility complex-related protein 1 (MR1), which displays microbe-derived vitamin B metabolites. Importantly, NKT and MAIT cells are rapid and potent producers of immunomodulatory cytokines. Therefore, they may be considered attractive targets during the early hyperinflammatory phase of sepsis when immediate interventions are urgently needed, and also in later phases when adjuvant immunotherapies could potentially reverse the dangerous state of immunosuppression. We will highlight recent findings that point to the significance or the therapeutic potentials of NKT and MAIT cells in sepsis and will also discuss what lies ahead in research in this area.

Effect of dietary glutamine on growth performance, non-specific immunity, expression of cytokine genes, phosphorylation of target of rapamycin (TOR), and anti-oxidative system in spleen and head kidney of Jian carp (Cyprinus carpio var. Jian)

This study was designed to investigate the effects of dietary glutamine on the growth performance, cytokines, target of rapamycin (TOR), and antioxidant-related parameters in the spleen and head kidney of juvenile Jian carp (Cyprinus carpio var. Jian). Fish were fed the basal (control) and glutamine-supplemented (12.0 g glutamine kg(-1) diet) diets for 6 weeks. Results indicated that the dietary glutamine supplementation improved the growth performance, spleen protein content, serum complement 3 content, and lysozyme activity in fish. In the spleen, glutamine down-regulated the expression of the interleukin 1 and interleukin 10 genes, and increased the level of phosphorylation of TOR protein. In the head kidney, glutamine down-regulated the tumor necrosis factor α and interleukin 10 gene expressions, phosphorylated and total TOR protein levels, while up-regulated the transforming growth factor β2 gene expression. Furthermore, the protein carbonyl content was decreased in the spleen of fish fed glutamine-supplemented diet; conversely, the anti-hydroxyl radical capacity and glutathione content in the spleen were increased by glutamine. However, diet supplemented with glutamine did not affect the lipid peroxidation, anti-superoxide anion capacity, and antioxidant enzyme activities in the spleen. Moreover, all of these antioxidant parameters in the head kidney were not affected by glutamine. Results from the present experiment showed the importance of dietary supplementation of glutamine in benefaction of the growth performance and several components of the innate immune system, and the deferential role in cytokine gene expression, TOR kinase activity, and antioxidant status between the spleen and head kidney of juvenile Jian carp.

Mechanism of glutamine inhibition of cytosolic phospholipase a2 (cPLA2 ): Evidence of physical interaction between glutamine-Induced mitogen-activated protein kinase phosphatase-1 and cPLA2

Non-essential amino acid L-glutamine (Gln) possesses anti-inflammatory activity via deactivating cytosolic phospholipase A2 (cPLA2 ). We showed previously that Gln deactivated cPLA2 indirectly via dephosphorylating p38 mitogen-activated protein kinase (MAPK), the major kinase for cPLA2 phosphorylation, through inducing MAPK phosphatase-1 (MKP-1). In this study, we investigated the precise mechanism underlying Gln deactivation of cPLA2 . In lipopolysaccharide (LPS)-treated mice, Gln injection resulted in dephosphorylation of phosphorylated cPLA2 (p-cPLA2 ), which coincided with rapid Gln induction of MKP-1. MKP-1 small interfering RNA (siRNA) abrogated the ability of Gln to induce MKP-1 as well as the dephosphorylation of cPLA2 . Co-immunoprecipitation and in-situ proximity ligation assay revealed a physical interaction between MKP-1 and p-cPLA2 . In a murine model of allergic asthma, we also demonstrated the physical interaction between MKP-1 and p-cPLA2 . Furthermore, Gln suppressed various allergic asthma phenotypes, such as neutrophil and eosinophil recruitments into the airway, airway levels of T helper type 2 (Th2) cytokines [interleukin (IL)-4, IL-5 and IL-13], airway hyperresponsiveness, mucin production and metabolites (leukotriene B4 and platelet-activating factor) through inhibiting cPLA2 in a MKP-1-dependent manner. These data suggest that MKP-1 uses cPLA2 , in addition to p38, as a substrate, which further potentiates the anti-inflammatory action of Gln.

Antioxidants as a treatment for acute pancreatitis: A meta-analysis

OBJECTIVE

To assess the efficacy of antioxidants in acute (AP) pancreatitis.

METHODS

We searched PubMed, Embase and the Cochrane library for all randomized controlled trials (RCT) involving administration of antioxidants in the therapy of AP until February 2012. AP studies were pooled to analyze the effect of antioxidants on hospital stay, mortality, and complications. Subgroup analyses were performed on the use of the antioxidant glutamine.

RESULTS

In total, eleven RCTs were included. Among patients with AP, antioxidant therapy resulted in a borderline significant reduction in hospital stay (mean difference -1.74; 95%CI -3.56 to 0.08), a significant decrease in complications (RR 0.66; 95%CI 0.46-0.95) and a non-significant decrease in mortality rate (RR 0.66; 95%CI 0.30-1.46). Subgroup analyses showed that glutamine significantly reduced complications (RR 0.51; 95%CI 0.34-0.78) and mortality rate (RR 0.33; 95%CI 0.13-0.85).

CONCLUSION

The present meta-analysis shows a possible benefit of glutamine supplementation in patients with acute pancreatitis. However, large randomized trials are needed to confirm these observations.

Glutamine attenuates acute lung injury caused by acid aspiration

Inadequate ventilator settings may cause overwhelming inflammatory responses associated with ventilator-induced lung injury (VILI) in patients with acute respiratory distress syndrome (ARDS). Here, we examined potential benefits of glutamine (GLN) on a two-hit model for VILI after acid aspiration-induced lung injury in rats. Rats were intratracheally challenged with hydrochloric acid as a first hit to induce lung inflammation, then randomly received intravenous GLN or lactated Ringer's solution (vehicle control) thirty min before different ventilator strategies. Rats were then randomized to receive mechanical ventilation as a second hit with a high tidal volume (TV) of 15 mL/kg and zero positive end-expiratory pressure (PEEP) or a low TV of 6 mL/kg with PEEP of 5 cm H2O. We evaluated lung oxygenation, inflammation, mechanics, and histology. After ventilator use for 4 h, high TV resulted in greater lung injury physiologic and biologic indices. Compared with vehicle treated rats, GLN administration attenuated lung injury, with improved oxygenation and static compliance, and decreased respiratory elastance, lung edema, extended lung destruction (lung injury scores and lung histology), neutrophil recruitment in the lung, and cytokine production. Thus, GLN administration improved the physiologic and biologic profiles of this experimental model of VILI based on the two-hit theory.

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.

Anti-inflammatory effects of glutamine on LPS-stimulated human dental pulp cells correlate with activation of MKP-1 and attenuation of the MAPK and NF-κB pathways

AIM

To evaluate the anti-inflammatory effects of glutamine and the underlying signal pathway mechanisms in lipopolysaccharide (LPS)-stimulated human dental pulp cells (HDPCs).

METHODS

Human dental pulp cells were exposed to 10 μg mL(-1) LPS and various concentrations of glutamine for 24 h. The production of PGE2 and nitric oxide was determined by enzyme-linked immunosorbent assay (ELISA) and Griess reagent kit, respectively. Cytokines were examined by ELISA, reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time PCR. iNOS and COX protein expression as well as signal pathways were accessed by Western blot. The data were analysed by anova with Bonferroni's test (α = 0.05).

RESULTS

Glutamine reduced LPS-induced iNOS and COX-2 protein expression as well as production of NO and PGE2 in a dose-dependent fashion. Additionally, glutamine suppressed the production and mRNA expression of inflammatory cytokines including interleukin-1β (IL-1β), TNF-α, and IL-8. Furthermore, glutamine attenuated phosphorylation of extracellular signal-regulated kinase (ERK), p38, c-Jun N-terminal kinase (JNK) and IκB-α, and nuclear translocation of NF-κB p65, but enhanced mitogen-activated protein kinase phosphatase-1 (MKP-1) expression in LPS-treated HDPCs.

CONCLUSION

Glutamine exerted an anti-inflammatory effect via activation of MKP-1 and inhibition of the NF-κB and MAPK pathways in LPS-treated HDPCs.

Heat shock protein 72 expressing stress in sepsis: unbridgeable gap between animal and human studies--a hypothetical "comparative" study

Heat shock protein 72 (Hsp72) exhibits a protective role during times of increased risk of pathogenic challenge and/or tissue damage. The aim of the study was to ascertain Hsp72 protective effect differences between animal and human studies in sepsis using a hypothetical “comparative study” model. Forty-one in vivo (56.1%), in vitro (17.1%), or combined (26.8%) animal and 14 in vivo (2) or in vitro (12) human Hsp72 studies (P < 0.0001) were enrolled in the analysis. Of the 14 human studies, 50% showed a protective Hsp72 effect compared to 95.8% protection shown in septic animal studies (P < 0.0001). Only human studies reported Hsp72-associated mortality (21.4%) or infection (7.1%) or reported results (14.3%) to be nonprotective (P < 0.001). In animal models, any Hsp72 induction method tried increased intracellular Hsp72 (100%), compared to 57.1% of human studies (P < 0.02), reduced proinflammatory cytokines (28/29), and enhanced survival (18/18). Animal studies show a clear Hsp72 protective effect in sepsis. Human studies are inconclusive, showing either protection or a possible relation to mortality and infections. This might be due to the fact that using evermore purified target cell populations in animal models, a lot of clinical information regarding the net response that occurs in sepsis is missing.

Effects of glutamine on proliferation, migration, and differentiation of human dental pulp cells

INTRODUCTION

Although glutamine (Gln) is mitogenic in various cell types, little is known about its role in human dental pulp cells (HDPCs). This study investigated the effects of Gln on proliferation, migration, and odontoblastic differentiation of HDPCs and the underlying signal pathway mechanisms.

METHODS

Growth and migration were assessed by cell counting and colorimetric cell migration kits. Differentiation was measured as alkaline phosphatase activity, calcified nodule formation by alizarin red staining, and marker mRNA expression by reverse transcriptase-polymerase chain reaction (RT-PCR). Chemokine expression was also evaluated by RT-PCR. Signal transduction pathways were examined by RT-PCR and Western blot analysis.

RESULTS

Gln dose-dependently increased proliferation, migration, alkaline phosphatase activity, mineralized nodule formation, and odontoblast-marker mRNA of HDPCs. Gln also up-regulated expression of interleukin-6, interleukin-8, MCP-1, MIP-3α, CCL2, CCL20, and CXCL1. Gln increased BMP-2 and BMP-4 mRNA, phosphorylation of Smad 1/5/8, β-catenin, and key proteins of the Wnt signaling pathway. Furthermore, Gln resulted in up-regulation of extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase. In addition, noggin, DKK1, inhibitors of p38, ERK, and JNK significantly attenuatted Gln-induced growth, migration, and odontoblastic differentiation.

CONCLUSIONS

Collectively, this study demonstrated that Gln promoted growth, migration, and differentiation in HDPCs through the BMP-2, Wnt, and MAPK pathways, leading to improved pulp repair and regeneration.

Potential nutritional strategies for the amelioration or prevention of high rigor temperature in cattle – a review

Environmental conditions influence animal production from an animal performance perspective and at the carcass level post-slaughter. High rigor temperature occurs when the animal is hyperthermic pre-slaughter, and this leads to tougher meat. Hyperthermia can result from increased environmental temperature, exercise, stress or a combination of these factors. Consumer satisfaction with beef meat is influenced by the visual and sensory traits of the product when raw and cooked, with beef consumers commonly selecting tenderness of the product as the most important quality trait. High rigor temperature leads to a reduction in carcass and eating quality. This review examines some possible metabolic causes of hyperthermia, with focus on the importance of adipose tissue metabolism and the roles of insulin and leptin. Potential strategies for the amelioration or prevention of high rigor temperature are offered, including the use of dietary supplements such as betaine and chromium, anti-diabetic agents such as thiazolidinediones, vitamin D, and magnesium (Mg) to provide stress relief.

Dynamic O-GlcNAcylation and its roles in the cellular stress response and homeostasis

O-linked N-acetyl-β-D-glucosamine (O-GlcNAc) is a ubiquitous and dynamic post-translational modification known to modify over 3,000 nuclear, cytoplasmic, and mitochondrial eukaryotic proteins. Addition of O-GlcNAc to proteins is catalyzed by the O-GlcNAc transferase and is removed by a neutral-N-acetyl-β-glucosaminidase (O-GlcNAcase). O-GlcNAc is thought to regulate proteins in a manner analogous to protein phosphorylation, and the cycling of this carbohydrate modification regulates many cellular functions such as the cellular stress response. Diverse forms of cellular stress and tissue injury result in enhanced O-GlcNAc modification, or O-GlcNAcylation, of numerous intracellular proteins. Stress-induced O-GlcNAcylation appears to promote cell/tissue survival by regulating a multitude of biological processes including: the phosphoinositide 3-kinase/Akt pathway, heat shock protein expression, calcium homeostasis, levels of reactive oxygen species, ER stress, protein stability, mitochondrial dynamics, and inflammation. Here, we will discuss the regulation of these processes by O-GlcNAc and the impact of such regulation on survival in models of ischemia reperfusion injury and trauma hemorrhage. We will also discuss the misregulation of O-GlcNAc in diseases commonly associated with the stress response, namely Alzheimer's and Parkinson's diseases. Finally, we will highlight recent advancements in the tools and technologies used to study the O-GlcNAc modification.

Alanyl-glutamine administration suppresses Th17 and reduces inflammatory reaction in dextran sulfate sodium-induced acute colitis

T helper (Th) cells play a major role in the pathogenesis of inflammatory bowel disease (IBD). Glutamine (Gln) is known to have immunomodulatory effects in metabolic stressed conditions. This study investigated the effects of post-treatment of alanyl-glutamine (Ala-Gln) on Th cell-associated cytokine expressions and inflammatory reaction in dextran sulfate sodium (DSS)-induced colitis. C57BL/6 mice received distilled water containing 3% DSS for 5 days to induce colitis, whereas the normal control (NC) group received distilled water. After induction of colitis, one of the colitis groups (DG) was intraperitoneally injected with an Ala-Gln solution (0.5 g Gln/kg/d), and the saline DSS group (DS) received an identical volume of saline. After treatment for 3 days, mice were sacrificed, and the blood and tissue samples were collected for further analysis. DSS colitis resulted in higher percentages of blood interleukin (IL)-17-secreting Th cells and greater expression of Th cell-associated cytokine messenger RNA (mRNA) in the mesenteric lymph nodes (MLN). Also, luminal immunoglobin (Ig) G, keratinocyte-derived chemokine, and macrophage chemoattractant protein-1 levels were higher in the DS group than the NC group, whereas these parameters did not differ between the DG and NC groups. The DG group had lower blood IL-17A, 17F, MLN IL-17 mRNA and macrophage percentage in the peritoneal lavage fluid than those of the DS group. These results suggest that post-treatment with Ala-Gln suppressed Th17-associated cytokine expressions, reduced macrophage infiltration into the peritoneal cavity and decreased pro-inflammatory cytokine production in the colon, thus may have attenuated inflammatory response in DSS-induced colitis.

Glutamine suppresses airway neutrophilia by blocking cytosolic phospholipase A(2) via an induction of MAPK phosphatase-1

Neutrophils are inflammatory cells that may contribute in a crucial way to the pathophysiology of steroid-resistant severe asthma. We previously reported that the nonessential amino acid l-glutamine (Gln) suppressed the recruitment of neutrophils into the airway in a murine model of asthma. In this study, we investigated the mechanisms by which Gln exerts beneficial effects in airway neutrophilia. We used the model we previously developed, which is suitable for examining sequential early asthmatic events, including neutrophil infiltration. Gln suppressed airway neutrophilia in a CXC chemokine-independent way. Airway neutrophilia was associated with cytosolic phospholipase A(2) (cPLA(2)) and 5-lipoxygenase (5-LO) activities. p38 MAPK, the upstream pathway of cPLA(2) and 5-LO, played a key role in inducing airway neutrophilia. Gln inhibited not only the phosphorylation of cPLA(2) and p38 MAPK but also leukotriene B(4) levels in the airways. Gln induced the early induction of MAPK phosphatase-1 (MKP-1) protein, a negative regulator of p38. MKP-1 small interfering RNA abrogated all the effects of Gln. Our results suggest that pathways involving p38/cPLA(2)/5-LO have a major role in airway neutrophilia. Gln suppresses airway neutrophilia via inhibiting p38 MAPK and its downstream pathways in an MKP-1-dependent way, which may provide a novel therapeutic strategy for pulmonary neutrophilic inflammatory diseases.

Glutamine suppresses DNFB-induced contact dermatitis by deactivating p38 mitogen-activated protein kinase via induction of MAPK phosphatase-1

L-glutamine (Gln) is a nonessential amino acid that is the most abundant amino acid in plasma. Gln has been reported to have an anti-inflammatory activity that involves deactivation of mitogen-activated protein kinases (MAPKs) in a MAPK phosphatase (MKP)-1-dependent manner. This study investigated the role of Gln in the inhibition of DNFB-induced allergic contact dermatitis (CD) in the ears of mice, and specifically the involvement of Gln in p38 MAPK inhibition. Topical application of Gln or the p38 inhibitor, SB202190, suppressed DNFB-induced CD. Gln application inhibited DNFB-induced p38 phosphorylation. Western blot analysis revealed that Gln application resulted in early phosphorylation and protein induction of MKP-1. MKP-1 small interfering RNA (siRNA), but not control siRNA, abrogated Gln-mediated early phosphorylation, protein induction of MKP-1, deactivation of p38, and Gln-mediated suppression of CD. The extracellular signal-regulated kinase (ERK) inhibitor, U0126, blocked Gln-induced MKP-1 phosphorylation and protein induction, as well as Gln suppression of CD. These results suggest that Gln suppresses DNFB-induced CD via deactivation of p38 MAPK through the early induction of MKP-1, the negative regulator of p38, in an ERK-dependent manner.

Effects of alanyl-glutamine dipeptide on the expression of colon-inflammatory mediators during the recovery phase of colitis induced by dextran sulfate sodium

PURPOSE

Glutamine (Gln) is a nutrient with immunomodulatory effects in metabolic stressed conditions. This study investigated the effects of Gln on colonic-inflammatory-mediator expression and mucosal repair in mice with dextran sulfate sodium (DSS)-induced colitis.

METHODS

C57BL/6 mice received distilled water containing 3 % DSS for 5 d to induce colitis. One of the DSS-treated groups was intraperitoneally injected with an alanyl (Ala)-Gln solution 3 days before (G-DSS) while the other group was administered Ala-Gln 3 days after colitis (DSS-G) was induced. The Ala-Gln solution provided 0.5 g Gln/kg/d. The saline-DSS group (S-DSS) received an identical amount of saline before and after colitis was induced to serve as a positive control.

RESULTS

The S-DSS group had a shorter colon length, higher plasma haptoglobin level, and more-severe colon inflammation. Also, the toll-like receptor (TLR)4 level, nuclear factor (NF)-κB activation, and inflammatory cytokine gene expression in the colon were higher than those of the normal control group. Gln administration either before or after colitis suppressed TLR4 protein levels, decreased plasma haptoglobin, and reduced colon inflammation. Histological inflammatory scores were also lowered. Compared to the post-colitis Gln group, preventive use of Gln had higher colon length, expressions of mucin 2, trefoil factor 3, and heat shock protein 72 genes were also upregulated in the colon.

CONCLUSIONS

These results suggest that Gln administered either before or after the colitis mitigated inflammation of colitis that was not observed in group without Gln injection. Prophylactic treatment with Gln had more-beneficial effects on reducing inflammatory markers and enhancing the recovery of mucosa in DSS-induced colitis.

Effects of glutamine supplementation on the immune status in weaning piglets with intrauterine growth retardation

Neonates with intrauterine growth retardation (IUGR) often suffer from impaired cellular immunity, and weaning may further aggravate adverse effects of IUGR on development and function of the immune system. In this study, we investigated effects of glutamine supplementation on immune status in the intestines of weaning pigs with IUGR, focusing on molecular mechanisms underlying altered immune response. Piglets with IUGR were weaned at 21 days of age and received orally 1.22 g alanine or 1 g glutamine per kg body weight every 12 h. Weight gain and intestinal weight of weaning piglets were increased by glutamine supplementation. Levels of serum IgG in piglets supplemented with glutamine were increased compared with Control piglets. The production of IL-1 and IL-8 in the serum and jejunum was decreased by glutamine supplementation, whereas the levels of IL-4 in the serum and the concentrations of IL-4 and IL-10 in the jejunum were increased. The expression of heat shock protein 70 (Hsp70) in the jejunum was increased by glutamine supplementation, but the degradation of inhibitor κB and the activity of nuclear factor-κB (NF-κB) were decreased. In conclusion, glutamine supplementation enhanced immune response in weaning piglets with IUGR. The effects of glutamine in IUGR are associated with increased Hsp70 expression and suppression of NF-κB activation.

Polysaccharides from extracts of Antrodia camphorata mycelia and fruiting bodies modulate inflammatory mediator expression in mice with polymicrobial sepsis

OBJECTIVES

Antrodia camphorata (AC) is a traditional Chinese medicine, and the polysaccharides contained within AC (AC-PSs) are reported to possess various biological functions. This study extracted AC-PSs from mycelia and fruiting bodies and evaluated their influences on inflammatory mediator expressions in septic mice.

METHODS

There were one normal control (NC) and three experimental groups. The normal control group underwent a sham operation, whereas the experimental groups underwent cecal ligation and puncture (CLP) to induce sepsis. Mice in the experimental groups were further divided into saline, mycelia, and fruiting body treatment groups. Saline or AC-PSs were injected intraperitoneally twice at 0.5 and 1 h after CLP and the mice were sacrificed at 6 or 16 h after sepsis for further analysis.

RESULTS

Compared with the normal control group, interleukin (IL)-6, tumor necrosis factor-α, IL-10, and monocyte chemotactic protein-1 levels in plasma and/or peritoneal lavage fluid in the septic mice dramatically increased after CLP. The increased levels of these inflammatory mediators in the two AC-PS-treated groups had decreased by 16 h after CLP. Messenger RNA expressions of tumor necrosis factor-α, IL-6, and IL-10 in the splenocytes were lower in the 2 AC-PS-treated groups than in the saline group. Consistent with the results, lung nuclear factor-κB expressions decreased and less severe interstitial inflammation was observed in the histologic finding after CLP in mice that had received AC-PSs. The fruiting body group had higher white blood cell counts and lower IL-6 levels in the peritoneal lavage fluid 6 h after CLP, whereas the interferon-γ level was higher 16 h after CLP than in the saline group. These alterations were not found in mice injected with the mycelia extract.

CONCLUSION

The administration of AC-PSs from mycelia or fruiting bodies decreased the inflammatory mediator expressions at the location of injury and in the circulation, especially in the late stage of sepsis. AC-PSs from fruiting bodies seemed to be more effective in decreasing the inflammatory response than those from mycelia. These findings suggest that AC-PSs from mycelia and fruiting bodies have potential protective effects against polymicrobial sepsis.

Effects of adenosine A₂A receptor activation and alanyl-glutamine in Clostridium difficile toxin-induced ileitis in rabbits and cecitis in mice

Background

Severe Clostridium difficile toxin-induced enteritis is characterized by exuberant intestinal tissue inflammation, epithelial disruption and diarrhea. Adenosine, through its action on the adenosine A_2A receptor, prevents neutrophillic adhesion and oxidative burst and inhibits inflammatory cytokine production. Alanyl-glutamine enhances intestinal mucosal repair and decreases apoptosis of enterocytes. This study investigates the protection from enteritis by combination therapy with ATL 370, an adenosine A_2A receptor agonist, and alanyl-glutamine in a rabbit and murine intestinal loop models of C. difficile toxin A-induced epithelial injury.

Methods

Toxin A with or without alanyl-glutamine was administered intraluminally to rabbit ileal or murine cecal loops. Animals were also given either PBS or ATL 370 parenterally. Ileal tissues were examined for secretion, histopathology, apoptosis, Cxcl1/KC and IL-10.

Results

ATL 370 decreased ileal secretion and histopathologic changes in loops treated with Toxin A. These effects were reversed by the A_2A receptor antagonist, SCH 58261, in a dose-dependent manner. The combination of ATL 370 and alanyl-glutamine significantly further decreased ileal secretion, mucosal injury and apoptosis more than loops treated with either drug alone. ATL 370 and alanyl-glutamine also decreased intestinal tissue KC and IL-10.

Conclusions

Combination therapy with an adenosine A_2A receptor agonist and alanyl-glutamine is effective in reversing C. difficile toxin A-induced epithelial injury, inflammation, secretion and apoptosis in animals and has therapeutic potential for the management of C. difficile infection.

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.

Pretreatment with alanyl-glutamine suppresses T-helper-cell-associated cytokine expression and reduces inflammatory responses in mice with acute DSS-induced colitis

T-helper (Th) cells play a major role in initiating and shaping the pathologic response in inflammatory bowel disease (IBD). Glutamine (GLN) is a nutrient with immune-modulating effects. This study investigated the effect of GLN on cytokine expressions and inflammatory responses of three subsets of Th cells in dextran sulfate sodium (DSS)-induced IBD. There were one normal control (NC) and two DSS groups. Mice in the DSS groups drank distilled water containing 3% DSS for 5 days, whereas the NC group received distilled water. Mice in the G-DSS group were given intraperitoneal injection of 0.5 g GLN/kg/d for 3 days before receiving DSS water. The other DSS group (C-DSS) received an identical amount of amino acid solution without GLN. After induction of IBD, the mice were allowed to recover for 3 days and then were sacrificed. Blood and colon samples were collected for further analysis. The C-DSS group had higher percentages of blood interleukin (IL)-17A, IL-17F, IL-22, IL-4 and interferon-γ than the NC group. The G-DSS group had lower Th1/Th17/Th2 cytokine expressions, which showed no differences from the NC group. Plasma haptoglobin, colon immunoglobin G and chemokine levels and myeloperoxidase activities were higher in the DSS groups than the NC group. These parameters were significantly lower in the G-DSS than the C-DSS group. These results suggest that pretreatment with GLN suppressed Th-associated cytokine expressions and may consequently reduce inflammatory mediator production and leukocyte infiltration into tissues, thus ameliorating the severity of acute DSS-induced colitis.

Antioxidant therapy in acute pancreatitis: experimental and clinical evidence

SIGNIFICANCE

Oxidative stress plays an important role in the pathogenesis of both acute and chronic pancreatitis. Although its impact is well investigated and has been studied clinically in chronic pancreatitis, it is less well defined for acute pancreatitis.

RECENT ADVANCES

Pathophysiological aspects of oxidative stress in acute pancreatitis have shown that reactive oxidative species (ROS) participate in the inflammatory cascade, and mediate inflammatory cell adhesion and consecutive tissue damage. Furthermore, ROS are involved in the generation of pain as another important clinical feature of patients suffering from acute pancreatitis.

CRITICAL ISSUES

Despite sufficient basic and experimental knowledge and evidence, the step from bench to bedside has not been successfully performed. Only a limited number of clinical studies are available that can give convincing evidence for the use of antioxidants in the clinical setting of acute pancreatitis.

FUTURE DIRECTIONS

Future studies are required to evaluate potential benefits of antioxidative substances to attenuate the severity of acute pancreatitis. Special focus should be put on the aspect of pain generation and the progression from mild to severe acute pancreatitis in the clinical setting.

Polyamines mediate glutamine-dependent induction of the intestinal epithelial heat shock response

Heat shock proteins (Hsps) are highly conserved proteins that play a role in cytoprotection and maintaining intestinal homeostasis. Glutamine is essential for the optimal induction of intestinal epithelial Hsp expression, but its mechanisms of action are incompletely understood. Glutamine is a substrate for polyamine synthesis and stimulates the activity of ornithine decarboxylase (ODC), a key enzyme for polyamine synthesis, in intestinal epithelial cells. Thus we investigated whether polyamines (putrescine, spermidine, or spermine) and their precursor ornithine mediate the induction of Hsp expression in IEC-18 rat intestinal epithelial cells. As previously observed, glutamine was required for heat stress induction of Hsp70 and Hsp25, although it had little effect under basal conditions. Under conditions of glutamine depletion, supplementation of ornithine or polyamines restored the heat-induced expression of Hsp70 and Hsp25. When ODC was inhibited by α-difluoromethylornithine (DFMO), an irreversible ODC inhibitor, the heat stress induction of Hsp70 and Hsp25 was decreased significantly, even in the presence of glutamine. Ornithine, polyamines, and DFMO did not modify the nuclear localization of heat shock transcription factor 1 (HSF-1). However, DFMO dramatically reduced glutamine-dependent HSF-1 binding to an oligonucleotide with heat shock elements (HSE), which was increased by glutamine. In addition, exogenous polyamines recovered the DNA-binding activity. These results indicate that polyamines play a critical role in the glutamine-dependent induction of the intestinal epithelial heat shock response through facilitation of HSF-1 binding to HSE.

Pre-treatment with glutamine attenuates lung injury in rats subjected to intestinal ischaemia-reperfusion

BACKGROUND

Glutamine (Gln) is the most abundant amino acid in blood and tissue fluids and is considered to be essential in certain catabolic conditions. A series of studies has shown that glutamine can attenuate cytokine release, reduce organ damage and improve survival in a rat model of endotoxaemia. The hypothesis for this rat model study is that pre-treatment with Gln reduces the expression of ICAM-1 and attenuates lung injury induced by intestinal ischaemia-reperfusion (I/R).

METHODS

Sprague-Dawley rats were randomised into five groups, namely sham group (sham surgery), Gln groups (three different doses) and control group. Lung injury caused by intestinal I/R was evaluated using Evans blue dye concentration and histopathologic examination. The level of myeloperoxidase (MPO) was measured using biochemistry method. The expression of heat shock protein 70 (HSP 70) and ICAM-1 were detected using Western blot and real-time polymerase chain reaction (PCR) methods, respectively.

RESULTS

Compared with the control group, rats pre-treated with Gln before intestinal I/R demonstrated decreased Evans Blue content and MPO activities in lung tissue, reduced the expression of ICAM-1, attenuated lung injury evidenced by pathological change compared with lactated Ringer pre-treated rats. Gln administration increased HSP 70 mRNA and protein expression in lung tissue compared with control group.

CONCLUSION

Ischaemia-reperfusion injury increases the expression of ICAM-1 in the lung. This may contribute to the migration, accumulation and activation of neutrophils. Pre-treatment with Gln attenuates rat lung injury and reduces ICAM-1 expression.