Effect of rebamipide in treatment of Helicobacter pylori-associated duodenal ulcer: attenuation of chemokine expression and nitrosative damage

Anti-inflammatory effects of rebamipide according to Helicobacter pylori status in patients with chronic erosive gastritis: a randomized sucralfate-controlled multicenter trial in China-STARS study

The aim of the study was to investigate the effects of rebamipide on symptom, histology, endogenous prostaglandin, and mucosal oxygen free radicals in chronic erosive gastritis (CEG) patients by using sucralfate as a control. The trial also examined whether Helicobacter pylori infection would affect rebamipide-induced protection. A total of 453 endoscopy-confirmed CEG patients from 11 hospitals in China were enrolled in the study. They randomly received either rebamipide (100 mg t.i.d) or sucralfate (1.0 t.i.d) for 8 weeks with a ratio of 3:1. Per-protocol analysis (n = 415) showed the accumulated symptom score in the rebamipide group dropped from 5.54 +/- 0.97 to 0.80 +/- 0.47 after 8 weeks (P < 0.001 versus control). The endoscopic inflammation score in rebamipide group also decreased from 2.65 +/- 0.09 to 0.60 +/- 0.10, which showed better effects than sucralfate. It was shown a significant improvement (P < 0.01) in prostaglandin E2 (PGE(2)) contents in rebamipide-treated subjects mucosa (225.4 +/- 18.3 pg/g versus 266.7 +/- 14.7 pg/g) compared with that in sucralfate group after 8 weeks of treatment. Malondialdehyde (MDA) contents were significantly depressed both in the trial and control group. When Helicobacter pylori infection was considered, no statistically difference was found in the effect of rebamipide on either symptom or inflammation scores. In conclusion, Rebamipide demonstrated a stronger suppressive effect on the mucosal inflammation in chronic erosive gastritis than sucralfate. The gastroprotection induced by rebamipide is not influenced by H. pylori infection, which indicates its usage in the treatment of H. pylori-associated CEG.

Effect of OPC-12759 on EGF receptor activation, p44/p42 MAPK activity, and secretion in conjunctival goblet cells

The purpose of the study was to determine if OPC-12759 stimulates secretion from conjunctival goblet cells in culture and if it activates the EGF receptor (EGFR) and p44/p42 mitogen-activated protein kinase (MAPK) to cause mucin secretion. Conjunctival goblet cells were cultured from pieces of male rat conjunctiva. OPC-12759 was added at increasing concentrations and for varying times to the cultured cells. The cholinergic agonist carbachol was used as a positive control. In selected experiments an inhibitor of the EGFR, AG1478, or an inhibitor of the kinase that activates MAPK, U0126, were added before OPC-12759. Goblet cell secretion of high molecular weight glycoconjugates was measured by an enzyme-linked lectin assay using the lectin UEA-1. Activation of the EGFR and MAPK were determined with Western blotting analysis using antibodies specific to the phosphorylated and the total amounts of these proteins. We found that OPC-12759 induced goblet cell secretion in a time- and concentration-dependent manner. Inhibition of the EGFR with AG1478 blocked secretion stimulated by OPC-12759. Inhibition of MAPK with U0126 also blocked secretion stimulated by OPC-12759. OPC-12759 increased the phosphorylation of the EGFR and MAPK in a time-dependent manner. We concluded that OPC-12759 stimulates secretion from cultured conjunctival goblet cells by activating the EGFR, which then induces MAPK activity.

Functional promotor polymorphism in RANTES gene does not influence the clinical course of Helicobacter pylori infection

BACKGROUND AND AIMS

Helicobacter pylori was found to increase the transcription of RANTES as a potent chemoattractant cytokine in mucosal inflammation. The aim of this study was to test if a functional promotor polymorphism in the RANTES gene leading to a higher transcriptional activity influences the severity of the mucosal damage in H. pylori infected individuals.

METHODS

A single nucleotide polymorphism, C-471T, was genotyped by TaqMan technology in a sample of 344 consecutive patients with H. pylori infection undergoing upper gastrointestinal endoscopy and 370 blood donors. Association with the development of erosions and stomach or duodenum ulcers as well as atrophic gastritis were tested.

RESULTS

None of the genotypes were associated with the severity of mucosal damage in stomach or duodenum (P > 0.05).

CONCLUSION

Even though H. pylori itself induces expression of RANTES, at the transcriptional level, genetic variations leading to higher transcriptional activity do not modify the degree of inflammation.

Amelioration of oxidative stress with ensuing inflammation contributes to chemoprevention of H. pylori-associated gastric carcinogenesis

The gastric inflammatory response provoked by Helicobacter pylori (H. pylori) consists of infiltrations by neutrophils, lymphocytes, and macrophages, resulting in varying degrees of epithelial cell damage. H. pylori-associated inflammation not only activates various oxidant-producing enzymes such as NADPH oxidase and inducible nitric oxide synthase, but also lowers the antioxidant ascorbic acid in the stomach. Reactive oxygen metabolites and nitrogen metabolites generated by these enzymes react with each other to generate new or more potent reactive species. The specific types of cellular damage resulting from reactive oxygen metabolites include lipid peroxidation, protein oxidation, and oxidative DNA damage. All of these oxidative products can result in biochemical changes leading to cancer. A positive association has been demonstrated between H. pylori infection and gastric adenocarcinoma with increased oxidative stress. Therefore, appropriate treatment to reduce oxidative stress would be expected to prevent subsequent gastric carcinogenesis through lessening of H. pylori-associated inflammation. This review will provide evidence that antiinflammatory regimens can decrease the development of tumors and the amelioration of gastric inflammation might lead to chemoprevention strategies by the attenuation of oxidative stress.

Serum IL-8 as a possible marker for determining the status of Helicobacter pylori infection in patients with untreated and treated peptic ulcer

Failure to eradicate Helicobacter pylori can lead to peptic ulcer recurrence and gastric malignancy. Therefore, the objective of this study was to develop a noninvasive method for determining whether H. pylori infection was eradicated with antibiotic-based triple therapy. A total of 17 patients with duodenal ulcer (DU) and 17 with gastric ulcer (GU) were evaluated both before and after treatment. Outcomes included serum levels of interleukin-8 (IL-8), pepsinogen I, and gastrin, and the Wilcoxon signed rank test was used to test significance. Changes in these parameters were also correlated with disease status. In those patients where both GU and DU healing occurred as a result of treatment, most showed an increase in serum IL-8 and a decrease in serum pepsinogen. Serum gastrin levels were not significantly changed in either group. Posttreatment increases in serum IL-8 were seen in 15 of 17 (88%) recovered DU patients and 14 of 17 (82%) recovered GU patients (P<.05 for each). Posttreatment decreases in pepsinogen I were found in 15 of 17 DU and 15 of 17 GU patients (P<.05 for each). These preliminary findings suggest that an increase in serum IL-8 and possibly a decrease in pepsinogen I may be useful in identifying the successful eradication of H. pylori infection in patients with peptic ulcer treated with antibiotics. A more systematic analysis of these putative diagnostic markers is now warranted.

Gastric Helicobacter infection inhibits development of oral tolerance to food antigens in mice

The increase in the transcellular passage of intact antigens across the digestive epithelium infected with Helicobacter pylori may interfere with the regulation of mucosal immune responses. The aim of this work was to study the capacity of Helicobacter infection to inhibit the development of oral tolerance or to promote allergic sensitization and the capacity of a gastro-protective agent, rebamipide, to interfere with these processes in mice. Oral tolerance to ovalbumin (OVA) was studied in 48 C3H/He 4-week-old mice divided into four groups: (i) OVA-sensitized mice; (ii) OVA-"tolerized" mice (that is, mice that were rendered immunologically tolerant); (iii) H. felis-infected, OVA-tolerized mice; (iv) and H. felis-infected, OVA-tolerized, rebamipide-treated mice. Oral sensitization to hen egg lysozyme (HEL) was studied in 48 mice divided into four groups: (i) controls; (ii) HEL-sensitized mice; (iii) H. felis-infected, HEL-sensitized mice; and (iv) H. felis-infected, HEL-sensitized, rebamipide-treated mice. Specific anti-OVA or anti-HEL immunoglobulin E (IgE) and IgG1/IgG2a serum titers were measured by enzyme-linked immunosorbent assay. Additionally, the capacity of rebamipide to interfere with antigen presentation and T-cell activation in vitro, as well as absorption of rebamipide across the epithelial monolayer, was tested. H. felis infection led to the inhibition of oral tolerance to OVA, but rebamipide prevented this inhibitive effect of H. felis. H. felis infection did not enhance the sensitization to HEL, but rebamipide inhibited the development of this sensitization. Moreover, rebamipide inhibited in a dose-dependent manner antigen presentation and T-cell activation in vitro and was shown to be able to cross the epithelium at a concentration capable of inducing this inhibitory effect. We conclude that H. felis can inhibit the development of oral tolerance to OVA in mice and that this inhibition is prevented by rebamipide.

Comparison of the effects of rebamipide with those of cimetidine on chronic gastritis associated with Helicobacter pylori in Mongolian gerbils

BACKGROUND AND AIMS

The effects of rebamipide on chronic gastritis associated with Helicobacter pylori have not been well-defined. We compared these effects of rebamipide with those of cimetidine in Mongolian gerbils infected with H. pylori.

METHODS

Mongolian gerbils with or without H. pylori were divided into 10 groups 6 weeks after inoculation and fed diets containing a drug (rebamipide or cimetidine) or control diet. All animals were sacrificed 4 weeks after grouping. Their stomachs were examined for histology, colonization by H. pylori, myeloperoxidase activity (myeloperoxidase), production of neutrophil chemokine (CINC/KC) and tumour necrosis factor-alpha (TNF-alpha), and serum gastrin levels.

RESULTS

H. pylori colonized all of the inoculated animals. Neither rebamipide nor cimetidine decreased myeloperoxidase activity, but each reduced wet stomach weight in H. pylori-infected animals. The amount of increase in CINC/KC and TNF-alpha in gastric tissue caused by H. pylori infection was decreased by treatment with rebamipide or cimetidine. H. pylori infection increased serum gastrin levels, and this increase was significantly enhanced by cimetidine but not rebamipide.

CONCLUSIONS

Rebamipide may improve H. pylori-infected chronic gastritis by preventing the production of inflammatory cytokines and chemokines, as does cimetidine, but may be preferable to cimetidine for long-term administration for treatment of H. pylori-infected chronic gastritis due to its effect on serum gastrin levels.

Review article: clinical significance of mucosal-protective agents: acid, inflammation, carcinogenesis and rebamipide

While a great deal of clinical evidence has been found regarding anti-acids for the treatment of gastric disorders including peptic ulcers, not all disorders can be explained only by the hyperfunction of acid secretion. Especially in the Asian region, glandular atrophy is more prominent than in Western countries, therefore low acid output is often observed in these patients. Improvement of mucosal protection is rational therapy for these patients; this is the reason for use of these agents in Asian countries. Rebamipide has many biological activities for gastric mucosa such as increasing the blood flow and biosynthesis prostaglandins and the decrease of oxygen radicals. These suggest the possible efficacy of rebamipide in the prevention of both Helicobacter pylori-related and nonsteroidal anti-inflammatory drug (NSAID)-induced gastric injury, which has been proved by human studies. Rebamipide is the only mucosal-protective drug which can improve the histological gastritis in vivo, whereas anti-acids have a lesser effect in influencing gastritis. Improvement of gastritis is expressed not only in quantity but also in quality of gastritis, which is shown as the reduction of iNOS expression in the gastric mucosa. Clinically, it is suggested that rebamipide has the potential to prevent gastric carcinogenesis by improvement of histological gastritis.

Mechanism of the antiulcerogenic effect of Ganoderma lucidum polysaccharides on indomethacin-induced lesions in the rat

Many cytokines, in particular tumor necrosis factor (TNF)-alpha have been known to play an important role in the pathogenesis of gastric mucosal lesions caused by various factors such as drugs and Helicobacter pylori infection. Our previous studies have shown that the polysaccharide fractions isolated from the fruiting bodies of Ganoderma lucidum (GLPS) prevented indomethacin- and acetic acid-induced gastric mucosal lesions in the rat. However, the mechanisms remain unclear. This study aimed to investigate whether GLPS had a direct mucosal healing effect in the indomethacin-treated rat, and to explore the possible mechanisms by determining the gastric mucosal mRNA and protein levels of TNF-alpha and ornithine decarboxylase (ODC) activity. In addition, the effects of GLPS on the cellular proliferation, ODC and c-Myc protein expression and mucus synthesis in the rat gastric cell culture (RGM-1) were examined. The present study demonstrated that GLPS at 250 and 500 mg/kg by intragastric input caused ulcer-healing effect in the rat; this was accompanied with a significant suppression of TNF-alpha gene expression, but with an increased ODC activity. In RGM-1 cells, GLPS at 0.05, 0.25 and 1.0 mg/ml significantly enhanced [3H]thymidine incorporation and ODC activity in a concentration-dependent manner. However, these effects were abrogated by the addition of the ODC inhibitor, DL-alpha-difluoromethyl-ornithine (DFMO). GLPS at 0.25-1.0 mg/ml also increased mucus synthesis, as indicated by the increased D-[6-3H]glucosamine incorporation in RGM-1 cells. Furthermore, GLPS at 0.05-1.0 mg/ml increased the c-Myc protein expression. These findings indicated that GLPS produced a mucosal healing effect in the rat model, perhaps due partly to the suppression of TNF-alpha and induction of c-myc and ODC gene.