Glutamine improves intestinal barrier function in experimental biliary obstruction

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.

Present and Future Therapeutic Approaches to Barrier Dysfunction

There is converging and increasing evidence, but also uncertainty, for the role of abnormal intestinal epithelial barrier function in the origin and development of a growing number of human gastrointestinal and extraintestinal inflammatory disorders, and their related complaints. Despite a vast literature addressing factors and mechanisms underlying changes in intestinal permeability in humans, and its connection to the appearance and severity of clinical symptoms, the ultimate link remains to be established in many cases. Accordingly, there are no directives or clinical guidelines related to the therapeutic management of intestinal permeability disorders that allow health professionals involved in the management of these patients to carry out a consensus treatment based on clinical evidence. Instead, there are multiple pseudoscientific approaches and commercial propaganda scattered on the internet that confuse those affected and health professionals and that often lack scientific rigor. Therefore, in this review we aim to shed light on the different therapeutic options, which include, among others, dietary management, nutraceuticals and medical devices, microbiota and drugs, and epigenetic and exosomes-manipulation, through an objective evaluation of the scientific publications in this field. Advances in the knowledge and management of intestinal permeability will sure enable better options of dealing with this group of common disorders to enhance quality of life of those affected.

Probiotic and glutamine treatments attenuate alcoholic liver disease in a rat model

The pathogenesis underlying alcoholic liver disease (ALD), which is often a result of alcohol abuse, currently remains unclear. Previous studies have reported that enteric dysbiosis serves an important role in the pathogenesis of ALD. The present study aimed to investigate the effects of glutamine and probiotics on a rat model of alcoholic liver disease (ALD). Sixty male Sprague-Dawley rats were randomly divided into 6 groups including control (C), alcohol (M), alcohol + Golden Bifido (T), alcohol + glutamine (G), alcohol + Medilac-S® (N) and alcohol + Golden Bifido + glutamine (L). Histology, body weight (BW), triglycerides (TG), serum aspartate transaminase (AST), alanine aminotransferase (ALT), tumor necrosis factor (TNF-α), interleukin-6 (IL-6), diamine oxidase (DAO), occludin, endotoxin and D-lactate levels were assessed whilst changes in the gut flora were evaluated and compared. Results determined that all probiotic and glutamine treatments elevated the abnormally decreased BW and occludin levels whilst the abnormal elevated serum AST, ALT, TG, IL-6, TNF-α, DAO, endotoxin and D-lactate levels were significantly reduced following chronic ethanol consumption. Histopathological observation of the liver demonstrated that probiotic and glutamine treatments attenuated liver damage induced by alcohol. Moreover, sequencing determined that there was a reduction in Firmicutes as well as an increase in Actinobacteria, Proteobacteria and Porphyromonadaceae abundance in the ALD group compared with the healthy controls. However, these changes were prevented by glutamine and probiotic therapy. In conclusion, the present results suggested that probiotics and glutamine ameliorated ALD by suppressing inflammation and regulating the gut microbiota. Therefore, probiotic and glutamine treatments can potentially serve as therapies for the prevention and treatment of ALD.

Combined effects of tauroursodeoxycholic Acid and glutamine on bacterial translocation in obstructive jaundiced rats:

BACKGROUND

Bacterial Translocation is believed to be an important factor on mortality and morbidity in Obstructive Jaundiced.

AIMS

We investigated the probable or estimated positive effects of tauroursodeoxycholic acid, which has antibacterial and regulatory effects on intestinal flora, together with glutamine on BT in an experimental obstructive jaundiced rat model.

STUDY DESIGN

Animal experimentation.

METHODS

Forty adult, male, Sprague Dawley rats were used in this study. Animals were randomised and divided into five groups of eight each: sham (Sh); control (common bile duct ligation, CBDL); and supplementation groups administered tauroursodeoxycholic acid (CBDL+T), glutamine (CBDL+G), or tauroursodeoxycholic acid plus glutamine (CBDL+TG). Blood and liver, spleen, MLN, and ileal samples were taken via laparotomy under sterile conditions for investigation of bacterial translocation and intestinal mucosal integrity and hepatic function tests on the tenth postoperative day.

RESULTS

There were statistically significant differences in BT rates in all samples except the spleen of the CBDL+TG group compared with the CBDL group (p=0.041, p=0.026, and p=0.041, respectively).

CONCLUSION

It is essential to protect hepatic functions besides maintaining intestinal mucosal integrity in the active struggle against BT occurring in obstructive jaundice. The positive effect on intestinal mucosal integrity can be increased if glutamine is used with tauroursodeoxycholic acid, which also has hepatoprotective and immunomodulatory features.

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.

Glutamine supplementation decreases intestinal permeability and preserves gut mucosa integrity in an experimental mouse model

BACKGROUND

Glutamine (GLN) is the preferred fuel for enterocytes, and GLN supplementation is critical during stressful conditions. The aim of this study was to evaluate the effect of GLN on intestinal barrier permeability and bacterial translocation in a murine experimental model.

METHODS

Swiss male mice (25-30 g) were randomized into 3 groups: (1) sham group; (2) intestinal obstruction (IO) group; (3) IO and GLN (500 mg/kg/d) group. Two different experiments were carried out to assess intestinal permeability and bacterial translocation. In the first experiment, the animals were divided into the 3 groups described above and received diethylenetriamine pentaacetate radiolabeled with technetium ((99m)Tc) on the eighth day. At different time points after intestinal obstruction, blood was collected to determine radioactivity. The animals were killed, and the small intestine was removed for histological analyses. In the bacterial translocation study, on the eighth day all groups received Escherichia coli labeled with (99m)Tc. After 90 minutes, the animals underwent intestinal obstruction and were killed 18 hours later. Blood, mesenteric lymph nodes, liver, spleen, and lungs were removed to determine radioactivity. Statistical significance was considered when P < or = .05.

RESULTS

The levels of intestinal permeability and bacterial translocation were higher in the IO group than in the sham and GLN groups (P < .05). GLN decreased intestinal permeability and bacterial translocation to physiologic levels in the treated animals and preserved intestinal barrier integrity.

CONCLUSIONS

GLN had a positive impact on the intestinal barrier by reducing permeability and bacterial translocation to physiologic levels and preserving mucosal integrity.

Effects of glutamine and curcumin on bacterial translocation in jaundiced rats

AIM: To investigate the effect of curcumin on bacterial translocation and oxidative damage in an obstructive jaundice model and compare the results to glutamine, an agent known to be effective and clinically used.

METHODS: Twenty-four female Wistar-Albino rats, weighing 200-250 g, were randomly divided into three groups (8 in each group). After ligation of the common bile duct in all animals, Group I received oral normal saline, Group II received oral glutamine and Group III received oral curcumin for seven days. Blood samples via cardiac puncture, tissue samples (terminal ileum, liver and mesenteric lymph node) and peritoneal fluid were obtained from the animals at the time of death to investigate bacterial translocation and oxidative damage.

RESULTS: We observed that both glutamine and curcumin reduced bacterial translocation in blood, hepatocellular damage, plasma cytokine levels, oxidative tissue damage and apoptosis significantly compared to the control group. Additionally, glutamine showed protective effects on ileal epithelium and reduced villus atrophy.

CONCLUSION: On the basis of these findings, both curcumin and glutamine are thought to be effective in preventing or reducing bacterial translocation and oxidative damage in obstructive jaundice.

Possible links between intestinal permeability and food processing: A potential therapeutic niche for glutamine

Increased intestinal permeability is a likely cause of various pathologies, such as allergies and metabolic or even cardiovascular disturbances. Intestinal permeability is found in many severe clinical situations and in common disorders such as irritable bowel syndrome. In these conditions, substances that are normally unable to cross the epithelial barrier gain access to the systemic circulation. To illustrate the potential harmfulness of leaky gut, we present an argument based on examples linked to protein or lipid glycation induced by modern food processing. Increased intestinal permeability should be largely improved by dietary addition of compounds, such as glutamine or curcumin, which both have the mechanistic potential to inhibit the inflammation and oxidative stress linked to tight junction opening. This brief review aims to increase physician awareness of this common, albeit largely unrecognized, pathology, which may be easily prevented or improved by means of simple nutritional changes.

Alcohol, intestinal bacterial growth, intestinal permeability to endotoxin, and medical consequences: summary of a symposium

This report is a summary of the symposium on Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences, organized by National Institute on Alcohol Abuse and Alcoholism, Office of Dietary Supplements, and National Institute of Diabetes and Digestive and Kidney Diseases of National Institutes of Health in Rockville, Maryland, October 11, 2006. Alcohol exposure can promote the growth of Gram-negative bacteria in the intestine, which may result in accumulation of endotoxin. In addition, alcohol metabolism by Gram-negative bacteria and intestinal epithelial cells can result in accumulation of acetaldehyde, which in turn can increase intestinal permeability to endotoxin by increasing tyrosine phosphorylation of tight junction and adherens junction proteins. Alcohol-induced generation of nitric oxide may also contribute to increased permeability to endotoxin by reacting with tubulin, which may cause damage to microtubule cytoskeleton and subsequent disruption of intestinal barrier function. Increased intestinal permeability can lead to increased transfer of endotoxin from the intestine to the liver and general circulation where endotoxin may trigger inflammatory changes in the liver and other organs. Alcohol may also increase intestinal permeability to peptidoglycan, which can initiate inflammatory response in liver and other organs. In addition, acute alcohol exposure may potentiate the effect of burn injury on intestinal bacterial growth and permeability. Decreasing the number of Gram-negative bacteria in the intestine can result in decreased production of endotoxin as well as acetaldehyde which is expected to decrease intestinal permeability to endotoxin. In addition, intestinal permeability may be preserved by administering epidermal growth factor, l-glutamine, oats supplementation, or zinc, thereby preventing the transfer of endotoxin to the general circulation. Thus reducing the number of intestinal Gram-negative bacteria and preserving intestinal permeability to endotoxin may attenuate alcoholic liver and other organ injuries.

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.