Oral glutamine attenuates indomethacin-induced small intestinal damage

Research progress of non-steroidal anti-inflammatory drug-induced small intestinal injury

Non-steroidal anti-inflammatory drugs (NSAIDs) are used widely around the world because of their anti-inflammatory, analgesic, and antiplatelet activity. However, long-term application of NSAIDs can lead to complications. Previously, the clinical attention was dedicated to the NSAID-induced upper gastrointestinal complications. Recently, the detection rate of small intestinal damage related to NSAIDs has increased due to the wide use of endoscopes such as capsule endoscopy and double-balloon colonoscopy. Although the majority of patients have no significant symptoms, there are still a small percentage of patients who develop obvious symptoms or complicated ulcers that require therapeutic intervention. Despite significant advances in our understanding of NSAIDs, the treatment modality and regimen for NSAID-induced small intestinal damage have remained relatively unclear. This article will provide a comprehensive overview of NSAID-induced small intestinal damage with regard to the epidemiology, clinical manifestations, diagnosis, risk factors, pathogenesis, and treatment, in order to provide informative evidence for clinical practice.

Plasma-Free Amino Acid Profiles in Crohn's Disease: Relationship With the Crohn Disease Activity Index

We aimed to clarify the relationship between plasma-free amino acid (PFAA) profiles and the Crohn's disease (CD) activity index (CDAI) in patients with CD.

METHODS

We measured fasting PFAA concentrations in 29 patients with CD and their correlation with disease activity.

RESULTS

In all patients, significant correlations were noted between CDAI and concentrations of valine, methionine, leucine, histidine, tryptophan, alanine, tyrosine, total amino acids (TAAs), nonessential amino acids (NEAAs), essential amino acids (EAAs), and branched-chain amino acids (BCAAs). In patients with the ileo-colonic type of CD, significant correlations were noted between CDAI and valine, histidine, tryptophan, glutamine, TAA, NEAA, EAA, and BCAA. In ileal type, significant correlations were observed between CDAI and threonine, valine, histidine, serine, and glycine. In colonic type, significant correlations were noted between CDAI and valine, histidine, tryptophan, TAA, NEAA, EAA, and BCAA.

CONCLUSIONS

In patients with CD, plasma amino acids appear to be associated with disease activity.

Enteral glutamine differentially regulates Nrf 2 along the villus-crypt axis of the intestine to enhance glutathione levels

BACKGROUND AND AIM

Glutamine is an important energy source for the intestinal epithelium, and its supplementation protects intestinal epithelial cells by induction of glutathione. However, mechanisms of glutathione induction in cells at various stages of differentiation along the crypt to villus axis are not well understood. This study examined induction of glutathione in response to glutamine along the intestinal villus-crypt axis and evaluated regulatory mediators involved in the process.

METHODS

Animals were administered 4% glutamine in feed for 7 days, following which enterocytes at various stages of differentiation were isolated and glutathione levels and signaling mediators involved in its regulation were studied.

RESULTS

In control animals, glutathione levels were higher in the intestinal crypt than in the villus or middle region. This was accompanied by elevated expression of the modifier subunit of glutathione synthetase (GCLM) and the transcription factor Nrf2 when compared with cells from the villus and middle regions. These levels were further enhanced by glutamine throughout the intestine, although the effects were more dramatic in the crypt. In parallel to glutathione induction, glutamine supplementation also altered actin dynamics and proliferation in cells of the crypt.

CONCLUSIONS

These results suggest that the variation of glutathione levels along the villus-crypt axis in the intestine is due to gradients in expression of mediators such as glutamate cysteine ligase modifier subunit and Nrf2. The protective effects of glutamine supplementation seem to be most pronounced in the crypt, where it upregulates proliferation, glutathione levels and alters actin dynamics.

Proanthocyanidin from grape seed extracts protects indomethacin-induced small intestinal mucosal injury

Proanthocyanidin (grape seed proanthocyanidin extracts, GSPEs) is an antioxidant and scavenges free radicals. Excessive oxidative stress and free radical production are major components in the pathogenesis of NSAID-induced small intestinal injury. We investigated the effect of GSPEs on indomethacin-induced intestinal mucosal injury in the rat. Rats were allocated into four groups: the null control group, the indomethacin control group, the low-dose GSPEs group, and the high-dose GSPEs group. GSPEs were administered for 4 days. Then indomethacin and GSPEs were coadministered for the following 2 days by oral route. The dose of indomethacin was 200 mg/Kg. The doses of GSPEs were 100 mg/Kg for low-dose group and 300 mg/Kg for high-dose group. Luminal bleeding was solely observed in one of 5 rats from indomethacin control group. The number of ulcer count was reduced to 0.1 ± 0.3 per rat in GSPEs treated group compared to 1.4 ± 0.5 per rat in indomethacin control group. Submucosal inflammatory cell infiltration was also reduced to 50% in GSPEs treated group. The tissue level of prostaglandin E2 was not affected by GSPEs treatment. GSPEs attenuated the indomethacin-induced small intestinal injury irrespective of the tissue PGE2 depletion and glutathione consumption.

The association of IFI27 expression and fatigue intensification during localized radiation therapy: implication of a para-inflammatory bystander response

The mechanisms behind fatigue intensification during cancer therapy remain elusive. The interferon alpha-inducible protein 27 (IFI27) was the most up-regulated gene based on our previous microarray data in fatigued men with non-metastatic prostate cancer receiving localized external beam radiation therapy (EBRT). The purpose of this study was to confirm the IFI27 up-regulation and determine its association with fatigue intensification during EBRT. Peripheral blood samples and fatigue scores were collected at three time points—prior to EBRT, at midpoint, and at completion of EBRT. Confirmatory quantitative real time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA) were utilized to verify the microarray results. Subjects were a total of 40 Caucasian men with prostate cancer; 20 scheduled for EBRT (65.6 ± 7.5 years old), and 20 on active surveillance as controls (62.8 ± 6.1 years old). Significant IFI27 expression overtime during EBRT was confirmed by qPCR (p < 0.5), which correlated with fatigue scores during EBRT (R = −0.90, p = 0.006). Alterations in mechanisms associated with immune response and mitochondrial function that explain the up-regulation of IFI27 may provide an understanding of the pathways related to the intensification of fatigue during localized radiation therapy.

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.

Apple peel polyphenol extract protects against indomethacin-induced damage in Caco-2 cells by preventing mitochondrial complex I inhibition

The aim of this work was to investigate the role of mitochondrial dysfunction in the development of oxidative stress and cytotoxicity induced by indomethacin and to evaluate the potential of an apple peel polyphenol extract (APPE) in protecting against these events. Indomethacin induced, time-dependently, mitochondrial and oxidative perturbations which led to cell losses. An inhibition of complex I activity, shown for first time here, which resulted in a concomitant drop in cellular ATP and an increment in mitochondrial superoxide production, was observed after 10 min of exposure. These early cytotoxicity-triggering events were followed by an increase in the intracellular production of superoxide (20 min), an elevation in the activity of xanthine oxidase which led to an increased lipid peroxidation (30 min), and a decline in cell viability which manifested after 40 min. These events were selectively prevented using allopurinol, tempol and APPE (a standardized apple peel polyphenol extract). While the oxidative and cell lytic effects of indomethacin were equally prevented by the three agents, only APPE protected against complex I inhibition and its downstream oxidative consequences. Since tempol (a SOD mimetic) prevented the elevation in xanthine oxidase activity, and allopurinol (a xanthine oxidase inhibitor) totally abolished the increment in lipid peroxidation and loss of cell viability, it appears that a superoxide-dependent increase in xanthine oxidase activity is critical to trigger cytotoxicity. Thus, preventing the early increment in superoxide formation that, as a result of inhibiting complex I, takes place within mitochondria would be key toward protecting the cells against the oxidative and cytolytic effects of indomethacin. The ability of APPE in preventing the inhibition of complex I and the subsequent superoxide-dependent increase in XO activity warrants further studies to evaluate the mechanism involves in the protecting effect of APPE against the indomethacin-associated adverse effects in vivo.

Intestinal growth and morphology is associated with the increase in heat shock protein 70 expression in weaning piglets through supplementation with glutamine

The objectives of this study were to determine the effects of oral Gln supplementation on growth performance, intestinal morphology, and expression of heat shock protein (Hsp) 70 in weaning piglets. A total of 65 piglets after weaning at 21 d of age (d 0) were used in this experiment. Five piglets were randomly selected and euthanized initially at d 0 to determine baseline values for the expression of Hsp70 in the small intestine. The remaining piglets were randomly assigned to 1 of 2 treatments and received 0 or 1 g of oral Gln/kg of BW every 12 h. After piglets were humanely killed at d 3, 7, and 14 postweaning, the duodenum, jejunum, and ileum of piglets were sampled to evaluate intestinal morphology and the expression and localization of Hsp70. The results indicated that oral Gln supplementation increased plasma concentrations of Gln compared with those in control piglets (P < 0.05). Average daily gain and ADFI were greater in piglets orally supplemented with Gln than in control piglets during the whole period (P < 0.05). The incidence of diarrhea in piglets orally supplemented with Gln was 24% less than (P = 0.064) that in control piglets at 8 to 14 d after weaning. The weights of the jejunum and ileum were greater in piglets orally supplemented with Gln compared with those of control piglets relative to BW on d 14 postweaning (P < 0.05). The villus height and the villus height:crypt depth ratio in the jejunum and the ileum were greater in piglets receiving oral Gln on d 14 postweaning (P < 0.05) than in control piglets. These results indicate that Gln supplementation can influence the intestinal morphology of weaned piglets. The expression of hsp70 mRNA and Hsp70 proteins in the duodenum and jejunum was greater in piglets supplemented with Gln than in control piglets (P < 0.05). However, Gln supplementation had no effect on the expression of hsp70 mRNA and Hsp70 proteins in the ileum. Moreover, the localization of Hsp70 in the cytoplasm indicated that Hsp70 has a cytoprotective role in epithelial cell function and structure. These results indicate that Gln supplementation may be beneficial for intestinal health and development and may thus mitigate diarrhea and improve growth performance. The protective mechanisms of Gln in the intestine may be associated with the increase in Hsp70 expression.

Apple peel polyphenols protect against gastrointestinal mucosa alterations induced by indomethacin in rats

The stability of an apple peel polyphenol extract (APPE) with powerful antioxidant activity was evaluated under acidic conditions in vitro, and its protective effect against gastrointestinal damage was investigated in rats treated with indomethacin. The antioxidant activity of APPE remained stable at pH 2.0 for 4 h. In rats treated with indomethacin (40 mg/kg ig), the previous administration of APPE protected the gastric, intestinal, and colonic mucosa from oxidative stress by preventing increased malondialdehyde concentrations and decreasing the GSH/GSSG ratio. APPE also displayed anti-inflammatory effects by preventing neutrophil infiltration in the mucosa, as evidenced by the lower myeloperoxidase activity. These protective effects of APPE resulted in the prevention of macro- and microscopic damage and of barrier dysfunction along the gastrointestinal tract of the indomethacin-treated animals. This study supports the concept that apple peel polyphenols may be useful in the prevention and/or treatment of nonsteroidal anti-inflammatory drug-associated side effects.

GC/MS-based profiling of amino acids and TCA cycle-related molecules in ulcerative colitis

OBJECTIVE

The roles that amino acids play in immunity and inflammation are well defined, and the relationship between inflammatory bowel disease (IBD) and certain amino acids has recently attracted attention. In this study, the levels of amino acids and trichloroacetic acid (TCA) cycle-related molecules in the colonic tissues and sera of patients with ulcerative colitis (UC) were profiled by gas chromatography/mass spectrometry (GC/MS), with the aim of evaluating whether the clinical state induced by UC leads to variations in the amino acid profile.

MATERIALS AND METHODS

Colonic biopsy samples from 22 UC patients were used, as well as serum samples from UC patients (n = 13), Crohn's disease (CD) patients (n = 21), and healthy volunteers (n = 17).

RESULTS

In the GC/MS-based profiling of amino acids and TCA cycle-related molecules, lower levels of 16 amino acids and 5 TCA cycle-related molecules were observed in the colonic lesion tissues of the UC patients, and the serum profiles of amino acids and TCA cycle-related molecules of the UC patients were different from those of the CD patients and healthy volunteers.

CONCLUSIONS

Our study raises the possibility that GC/MS-based profiling of amino acids and TCA cycle-related molecules is a useful early diagnostic tool for UC.

GC/MS-based profiling of amino acids and TCA cycle-related molecules in ulcerative colitis

OBJECTIVE

The roles that amino acids play in immunity and inflammation are well defined, and the relationship between inflammatory bowel disease (IBD) and certain amino acids has recently attracted attention. In this study, the levels of amino acids and trichloroacetic acid (TCA) cycle-related molecules in the colonic tissues and sera of patients with ulcerative colitis (UC) were profiled by gas chromatography/mass spectrometry (GC/MS), with the aim of evaluating whether the clinical state induced by UC leads to variations in the amino acid profile.

MATERIALS AND METHODS

Colonic biopsy samples from 22 UC patients were used, as well as serum samples from UC patients (n = 13), Crohn's disease (CD) patients (n = 21), and healthy volunteers (n = 17).

RESULTS

In the GC/MS-based profiling of amino acids and TCA cycle-related molecules, lower levels of 16 amino acids and 5 TCA cycle-related molecules were observed in the colonic lesion tissues of the UC patients, and the serum profiles of amino acids and TCA cycle-related molecules of the UC patients were different from those of the CD patients and healthy volunteers.

CONCLUSIONS

Our study raises the possibility that GC/MS-based profiling of amino acids and TCA cycle-related molecules is a useful early diagnostic tool for UC.

Candida albicans susceptibility to lactoperoxidase-generated hypoiodite

In vivo, lactoperoxidase produces hypothiocyanite (OSCN⁻) from thiocyanate (SCN⁻) in the presence of hydrogen peroxide (H₂O₂); in vitro, iodide (I⁻) can be oxidized into hypoiodite (OI⁻) by this enzyme. The aim of this study was to compare in vitro the anti-Candida effect of iodide versus thiocyanate used as lactoperoxidase substrate to prevent Candida biofilms development. Candida albicans ATCC 10231 susceptibility upon both peroxidase systems was tested in three different experimental designs: (i) in a liquid culture medium, (ii) in an interface model between solid culture medium and gel containing the enzymic systems, (iii) in a biofilm model onto titanium and acrylic resin. Yeast growth in liquid medium was monitored by turbidimetry at 600 nm. Material-adherent yeast biomass was evaluated by the tetrazolium salt MTT method. The iodide-peroxidase system has been shown to inhibit Candida biofilm formation at lower substrate concentrations (~200 fold less H₂O₂ donor) and for longer incubation periods than the thiocyanate-peroxidase system. In conclusion, efficiency of lactoperoxidase-generated OI⁻ to prevent C. albicans biofilm development allows refining iodine antifungal use in ex vivo conditions.

Candida albicans biofilm on titanium: effect of peroxidase precoating

The present study aimed to document Candida albicans biofilm development on titanium and its modulation by a peroxidase-precoated material which can generate antimicrobials, such as hypoiodite or hypothiocyanite, from hydrogen peroxide, iodide, or thiocyanate. For this purpose, titanium (powder or foil) was suspended in Sabouraud liquid medium inoculated with C. albicans ATCC10231. After continuous stirring for 2-21 days at room temperature, the supernatant was monitored by turbidimetry at 600 nm and titanium washed three times in sterile Sabouraud broth. Using the tetrazolium salt MTT-formazan assay, the titanium-adherent fungal biomass was measured as 7.50 ± 0.60 × 10(6) blastoconidia per gram of titanium powder (n = 30) and 0.50 ± 0.04 × 10(6) blastoconidia per cm(2) of titanium foil (n = 12). The presence of yeast on the surface of titanium was confirmed by microscopy both on fresh preparations and after calcofluor white staining. However, in the presence of peroxidase systems (lactoperoxidase with substrates such as hydrogen peroxide donor, iodide, or thiocyanate), Candida growth in both planktonic and attached phases appeared to be inhibited. Moreover, this study demonstrates the possible partition of peroxidase systems between titanium material (peroxidase-precoated) and liquid environment (containing peroxidase substrates) to limit C. albicans biofilm formation.

Potential for amino acids supplementation during inflammatory bowel diseases

The pathophysiology of inflammatory bowel diseases (IBDs) is multifactorial and involves interactions of gut luminal content with mucosal barrier and especially immune cells. Malnutrition is a frequent issue during IBD flares, especially in Crohn's disease (CD) patients, and nutritional support is frequently used to treat malnutrition but also in an attempt to modulate intestinal inflammation. The use of oral or enteral nutrition intervention in IBDs may be effective, alone or in combination with drugs, to achieve and maintain remission. However, standard diets are less effective than new-generation biotherapies and could be improved by supplementation with specific immunomodulatory amino acids. Experimental studies evaluating glutamine, the preferential substrate for enterocytes, are promising. Some clinical studies with oral glutamine in CD are until now disappointing, but new formulations and targeting could enhance glutamine efficacy at the site of mucosal lesions. The role of arginine, involved in nitric oxide and polyamines synthesis, still remains debated. However, the effects of these amino acids in IBD have been poorly documented in humans. Other candidates like glycine, cysteine, histidine, or taurine should also be evaluated in the future.

Assessment and prevention of gastrointestinal toxicity of non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for analgesic, anti-inflammatory and, in the case of aspirin, for anti-thrombotic actions. The serious gastrointestinal side-effects associated with these drugs are of concern and pose a significant obstacle to their use. This review discusses the pathogenic mechanisms by which the conventional acidic NSAIDs induce gastrointestinal toxicity, with particular emphasis on non-prostaglandin effects. Methods of assessment of NSAID-induced enteropathy are reviewed, with particular emphasis on the use of functional measurement of NSAID-induced changes in the gastrointestinal tract. The advances in our knowledge of the pathogenesis of these effects have resulted in the development of a range of novel NSAIDs. Where functional assessment of the effects of NSAIDs has been employed, it appears to be more useful as an indicator of early-stage changes rather than a predictor of the effects of long-term NSAID exposure. Successful pharmaceutical strategies now offer considerable promise for reducing the severity of NSAID damage to the gastrointestinal tract. The utility of intestinal permeability measurements for selection and assessment of these strategies is discussed.

Dietary glutamine affects mucosal functions in rats with mild DSS-induced colitis

The development of inflammatory bowel disease may involve immune dysfunction. Because enteral glutamine is the main source of amino acids for the intestinal mucosa and is metabolized at high rates by both enterocytes and immunocytes, the aim of this study was to ascertain the protective role of glutamine supplementation in a DSS-induced model of mild experimental colitis on metabolic, immune, and intestinal variables. Lewis rats were fed diets supplemented with glutamine (glutamine diet, G group) or an isoenergetic isonitrogenous control diet (C group) from postnatal d 21 (weaning) and continuing to d 35. On d 30, half of the rats from both groups were given 0.5% DSS in drinking water (G-DSS and C-DSS groups). Glutamine supplementation increased the plasma concentrations of Thr, Gln, Cit, His, and Arg and enhanced the ratio of essential to nonessential amino acids irrespective of DSS treatment. DSS administration increased the plasma Gln concentration, indicating a reduced utilization of this amino acid by the intestinal tissue. Regarding the gut-associated lymphoid tissue lymphocyte populations, DSS increased the percentages of CD3(+) T lymphocytes from Peyer's patches, NK and B lymphocytes from mesenteric lymph nodes, and NK CD8(-) cells from intraepithelial lymphocytes. The administration of glutamine did not affect the inductive populations nor did it modify T-cell subtypes or the percentage of intraepithelial lymphocytes of gut-associated lymphoid tissue. However, glutamine supplementation reduced the feces water contents in the DSS-treated but not in the untreated rats. These results indicate that glutamine supplementation can improve barrier function in rats with colitis.

Effects of glutamine supplementation on gut barrier, glutathione content and acute phase response in malnourished rats during inflammatory shock

AIM: To evaluate the effect of glutamine on intestinal mucosa integrity, glutathione stores and acute phase response in protein-depleted rats during an inflammatory shock.

METHODS: Plasma acute phase proteins (APP), jejunal APP mRNA levels, liver and jejunal glutathione concentrations were measured before and one, three and seven days after turpentine injection in 4 groups of control, protein-restricted, protein-restricted rats supplemented with glutamine or protein powder. Bacterial translocation in mesenteric lymph nodes and intestinal morphology were also assessed.

RESULTS: Protein deprivation and turpentine injection significantly reduced jejunal villus height, and crypt depths. Mucosal glutathione concentration significantly decreased in protein-restricted rats. Before turpentine oil, glutamine supplementation restored villus heights and glutathione concentration (3.24 ± 1.05 vs 1.72 ± 0.46 μmol/g tissue, P < 0.05) in the jejunum, whereas in the liver glutathione remained low. Glutamine markedly increased jejunal α1-acid glycoprotein mRNA level after turpentine oil but did not affect its plasma concentration. Bacterial translocation in protein-restricted rats was not prevented by glutamine or protein powder supplementation.

CONCLUSION: Glutamine restored gut glutathione stores and villus heights in malnourished rats but had no preventive effect on bacterial translocation in our model.