Inhibitory effect of L-glutamine on the aspirin-induced gastric lesions in the rat

Effects of Immunonutrition on Chemoradiotherapy Patients: A Systematic Review and Meta-Analysis

OBJECTIVE

We conducted a systematic review to assess the effects of immunonutrition on chemoradiotherapy patients.

METHODS

We searched the Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, CINAHL, and the Web of Science. We assessed the risk of bias using the Cochrane Risk of Bias tool. Our primary outcomes were the incidence of oral mucositis and diarrhea. The secondary outcomes were the incidence of esophagitis, grade ≥3 oral mucositis, grade ≥3 diarrhea, grade ≥3 esophagitis, and body weight loss.

RESULTS

A total of 1478 patients and 27 studies were included. There were no significant differences in the incidence of oral mucositis (relative risk [RR] = 0.91; 95% confidence interval [CI], 0.79-1.05), diarrhea (RR = 0.89; 95% CI, 0.76-1.05), or esophagitis (RR = 0.55; 95% CI, 0.11-2.86) between the immunonutrition group and standard nutrition/placebo group. Nevertheless, immunonutrition significantly reduced the incidence of grade ≥3 oral mucositis (RR = 0.45; 95% CI, 0.22-0.92), grade ≥3 diarrhea (RR = 0.56; 95% CI, 0.35-0.88), grade ≥3 esophagitis (RR = 0.15; 95% CI, 0.04-0.54), and losing >5% body weight (RR = 0.34; 95% CI, 0.18-0.64).

CONCLUSIONS

In this study, immunonutrition failed to reduce the incidence rates of oral mucositis, diarrhea, or esophagitis but was conducive to significantly improving the severity of oral mucositis and diarrhea esophagitis and reducing the rate of body weight loss.

L-glutamine decreases the severity of mucositis induced by chemoradiotherapy in patients with locally advanced head and neck cancer: a double-blind, randomized, placebo-controlled trial

The incidence of severe mucositis in the oral cavity, pharynx and larynx is high among patients with head and neck cancer (HNC) receiving chemoradiotherapy (CRT), resulting in significant pain and impairment of quality of life. The present study investigated whether L-glutamine (glutamine) decreases the severity of mucositis in the oral cavity, pharynx and larynx induced by CRT. This double-blind, randomized, placebo-controlled trial included 40 untreated patients with squamous cell carcinoma of the nasopharynx, oropharynx, hypopharynx or larynx. Patients received 66 or 70 Gy of total radiation at the rate of 2 Gy/fraction daily and 5 fractions/week. Cisplatin (20 mg/m²) and docetaxel (10 mg/m²) were intravenously co-administered once a week for 6 weeks. Patients were randomized to orally receive either glutamine (group G) or placebo (group P) at a dose of 10 g 3 times a day throughout the CRT course. Mucositis was assessed using the National Cancer Institute Common Terminology Criteria for Adverse Events version 3.0. The primary end point was mucositis severity. Mucositis developed in all patients. A maximal mucositis grade of G4 was observed in 0 and 25% group G and P patients, respectively, while that of G2 was observed in 10 and 0% group G and P patients, respectively (p=0.023). Glutamine significantly decreased the maximal mucositis grade (group G, 2.9±0.3; group P, 3.3±0.4; p=0.005) and pain score at weeks 4, 5 and 6. Glutamine significantly decreased mucositis severity in the oral cavity, pharynx and larynx induced by CRT in patients with HNC.

New frontiers in gut nutrient sensor research: prophylactic effect of glutamine against Helicobacter pylori-induced gastric diseases in Mongolian gerbils

Ammonia is one of the important toxins produced by Helicobacter pylori (H. pylori), the major cause of peptic ulcer diseases. We examined whether glutamine or marzulene (a gastroprotective drug containing 1% sodium azulene and 99% glutamine) protects the gastric mucosa against H. pylori in vivo and investigated the mechanism underlying glutamine-induced mucosal protection against ammonia in gastric epithelial cells in vitro. Mongolian gerbils were fed for 3 months with a diet containing glutamine (2%-20%) or marzulene (20%) starting from 2 weeks or 2 years after H. pylori infection. Then, gastric mucosal changes were evaluated both macro- and microscopically. Cultured gastric epithelial cells were incubated in the presence of ammonia, with or without glutamine; and cell viability, ammonia accumulation, and chemokine production were determined. Gerbils exhibited edema, congestion, and erosion after 3-month infection; and after 2-year infection, they showed cancer-like changes in the gastric mucosa. Glutamine and marzulene significantly suppressed these pathological changes caused in the gastric mucosa by H. pylori infection. Ammonia was accumulated in the cells, resulting in an increase in chemokine production and a decrease in cell viability. These pathological responses were prevented by glutamine. In addition, glutamine decreased chemokine production and cell death through inhibition of cellular accumulation of ammonia, resulting in the prevention of H. pylori-induced gastric diseases in vivo. These results suggest that glutamine/marzulene would be useful for prophylactic treatment of H. pylori-induced gastric diseases in patients.

Inflammation and foveolar hyperplasia are reduced by supplemental dietary glutamine during Helicobacter pylori infection in mice

We recently showed that L-Gln protects cultured gastric cells from ammonia-induced cell death and predicted that Gln may also protect during Helicobacter pylori infection in vivo. Thus, the aim of this study was to test whether supplemental dietary Gln protects against H. pylori-associated pathology. For this, C57BL/6 mice were fed a purified diet consisting of 20.3% protein (1.9% Gln), 66% carbohydrate, and 5% fat or 25.3% protein (5% supplemental L-Gln; 6.9% total Gln), 61% carbohydrate, and 5% fat. After a 2-wk prefeeding period, mice were divided into sham-(uninfected) or H. pylori-infected groups. Body weight and food consumption were recorded weekly. Tissue histopathology, H. pylori colonization, serum IgG, and pro- and antiinflammatory cytokine mRNA expression were determined at 6, 12, and 20 wk postinfection (wkPI). Inflammation, antiinflammatory cytokine, and interleukin-1beta mRNA expression were significantly greater at 6 wkPI in H. pylori-infected mice fed supplemental Gln compared with those fed the control diet. At 20 wkPI, however, inflammation and foveolar hyperplasia were significantly lower in H. pylori-infected mice fed supplemental Gln compared with those fed the control diet. Body weight gain, food consumption, H. pylori colonization, and serum IgG did not differ in H. pylori-infected mice fed supplemental Gln compared with the control diet. Our data demonstrate that H. pylori-infected mice fed supplemental dietary Gln have reduced H. pylori-associated pathology in vivo that is accompanied by beneficial changes in the immune response to H. pylori early in infection. Thus, Gln supplementation may be an alternative therapy for reducing H. pylori-associated pathology.

Testing for drugs inhibiting the formation of gastric ulcers

Copper salicylate has been shown to be an inhibitor of gastric lesions in rats induced by aspirin, indomethacin and cold stress whereas cimetidine was only effective against those produced by cold stress. The results are in line with those reported earlier for the anti-ulcer activity of sodium salicylate and metiamide respectively. On this basis, it appears that the animal model of stress-induced gastric lesions in the rat is the most suitable for testing the activity of new-antiulcer drugs.

The role of gastric mucosal hexosamine in aspirin-induced ulcers

In order to elucidate the role of gastric tissue hexosamine, used as an index of mucopolysaccharide content, in the development and healing process of peptic ulcers, the distribution of hexosamine and the changes of gastric hexosamine content in the development and healing of aspirin-induced ulcers in rats were studied. In addition, the effects of proglumide and L-glutamine on gastric hexosamine were also studied. The hexosamine content was found to be the highest in the antrum, followed by the corpus and then the forestomach. The mucosa contained significantly higher hexosamine than the smooth muscle layer in both the antrum and the corpus. Prior treatment with proglumide significantly increased the mucosal hexosamine to the extent of 10.3--18.1% in the glandular stomach. Administration of aspirin decreased the gastric mucosal hexosamine and induced the onset of ulcer, while administration of proglumide suppressed the gastric lesions in proportion to dosage and correspondingly prevented a decrease of the hexosamine. In contrast, L-glutamine showed an anti-ulcerogenic effect without suppressing a decrease of the hexosamine. In the process of curing gastric lesions, proglumide accelerated the healing of the ulcers and simultaneously returned the total hexosamine content to its original level. These results suggest that the gastric mucosal hexosamine is closely related to the onset and healing of aspirin-induced ulcer in rats, and that proglumide contributes to both the prevention and healing of ulcers by increasing gastric mucosal hexosamine.

Inhibitors of gastric lesions in the rat

The production by stress of gastric lesions in rats was inhibited by metiamide and by mepyramine. Lesions induced by indomethacin treatment were inhibited by mepyramine but not by metiamide. Those induced by aspirin treatment in pylorus-ligated rats were not affected by either antihistamine drug. Oral glutamine inhibited lesion production in all three systems whereas aspirin orally markedly potentiated it. Sodium salicylate inhibited both indomethacin-induced lesions and those produced by aspirin in pylorus-ligated rats. On the other hand, copper salicylate inhibited stress-induced lesions and it, like copper aspirinate, also markedly reduced the extent of lesions produced by aspirin. On the basis of these results, stress-induced lesion production offers a suitable animal model for testing anti-ulcer drugs as it is, like most human gastric ulcers, inhibited by H2-receptor inhibitors like metiamide.

Effects of L-glutamine on acetylsalycylic acid induced gastric lesions and acid back diffusion in dogs

Effects of L-glutamine on acetylsalicylic acid (ASA)-induced gastric mucosal lesions were studied in mongrel dogs. It was confirmed that when oral ASA at 1.0 or 2.0 g per dog is given in two divided doses, there is severe and consistent dose-dependent mucosal damage in the glandular portion of the stomach in fasted dogs. However, when L-glutamine 2.0 or 4.0 g per dog in two divided doses is given concomitantly with ASA 2.0 g per dog orally, the gastric irritation is significantly inhibited. Instillation of 20 mM of ASA in 100 mM HCl solution into the Heidenhain pouch of Beagle dogs produced a significant loss of H+ from the pouch and a gain of Na+ in the lumen compared with ASA-free controls. When L-glutamine (100 mM) was given concomitantly with ASA (20 mM) into the pouch, changes of electrolyte fluxes in response to ASA alone were significantly suppressed. However, 50 mM of L-glutamine had no appreciable effect on acid back diffusion caused by ASA 20 mM. The amino acid itself had little effect on the ionic movement in the pouch. Gross bleeding from the pouch treated with ASA was never observed with the concomitant dosing of ASA and L-glutamine 50 or 100 mM.

Effects of L-glutamine of acetylsalicylic acid or taurocholic acid-induced gastric lesions and secretory changes in pylorus-ligated rats under normal or stress conditions

An oral dosing of either acetylsalicylic acid (ASA) or taurocholic acid (TCA) to pylorus-ligated rats subjected to water-immersion stress produced severe damage to the gastric musoca in contrast to the irritation observed in non-stressed ones. The irritative activity of ASA or TCA on gastric mucosa under stress was dose-dependent. Stress itself (23 degrees C, 7 hr) did not induce any appreciable changes in gastric mucosa under stress wasic mucosa of rats. L-glutamine, given together with SAS or TCA, significantly prevented the potentiated development of SAS- or TCA-induced gastric lesions in stressed rats. L-glutamine also prevented in varying degrees the reduction of acid and increment of Na+ ion in gastric juice accumulated in stressed rats in response to ASA or TCA.

Inhibitory effect of L-glutamine on gastric irritation and back diffusion of gastric acid in response to aspirin in the rat

L-Glutamine given orally at 750 mg/kg significantly reduced the formation of gastric mucosal lesions induced by aspirin at 100 mg/kg at 1, 3, and 7 hours in pylorus-ligated rats. L-Glutamine markedly inhibited the loss of H+ and a corresponding increment of Na+ through the aspirin-damaged mucosal barrier, which suggests inhibition of acid back diffusion as the mechanism of action. In vagotomized rats, the diffusion of H+ from the instilled acid solution into the gastric mucosa and outflux of Na+ from the mucosa into the lumen was so strong that aspirin could not show any acceleration of a back diffusion of H+ in contrast to the aspirin-free group. However, L-Glutamine given with or without aspirin inhibited the group. However, L-Glutamine given with or without aspirin inhibited the back diffusion of H+ instilled into the vagotomized rat stomach.