Rebamipide, novel prostaglandin-inducer accelerates healing and reduces relapse of acetic acid-induced rat gastric ulcer. Comparison with cimetidine

Rebamipide and Derivatives are Potent, Selective Inhibitors of Histidine Phosphatase Activity of the Suppressor of T Cell Receptor Signaling Proteins

The suppressor of T cell receptor signaling (Sts) proteins are negative regulators of immune signaling. Genetic inactivation of these proteins leads to significant resistance to infection. From a 590,000 compound high-throughput screen, we identified the 2-(1H)-quinolinone derivative, rebamipide, as a putative inhibitor of Sts phosphatase activity. Rebamipide, and a small library of derivatives, are competitive, selective inhibitors of Sts-1 with IC50 values from low to submicromolar. SAR analysis indicates that the quinolinone, the acid, and the amide moieties are all essential for activity. A crystal structure confirmed the SAR and reveals key interactions between this class of compound and the protein. Although rebamipide has poor cell permeability, we demonstrated that a liposomal preparation can inactivate the phosphatase activity of Sts-1 in cells. These studies demonstrate that Sts-1 enzyme activity can be pharmacologically inactivated and provide foundational tools and insights for the development of immune-enhancing therapies that target the Sts proteins.

The effect of rebamipide on non-steroidal anti-inflammatory drug-induced gastro-enteropathy: a multi-center, randomized pilot study

BACKGROUND/AIMS

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly-used medications, and ailments such as arthritis or heart disease, require long-term use of these drugs, which can induce gastroenteropathy with bleeding and ulcers. This study investigated the associations between efficacy, safety, and gastrointestinal symptoms linked to rebamipide and proton pump inhibitor administration in patients requiring long-term NSAID use.

METHODS

This study was a multi-center, randomized, open-labeled, pilot design.

RESULTS

Thirty-three patients were included. Of these, 15 were included in the study group and 18 were in the control group. NSAID-induced gastric ulcers, which were the primary outcome of this study, did not occur in either the study or control group. Changes in the number of small bowel erosions and ulcers were -0.6 ± 3.06 in the study group and 1.33 ± 4.71 in the control group. The number of subjects with mucosal breaks (defined as multiple erosions and/or ulcers) was three (20%) in the study group and six (40%) in the control group (p = 0.427). No serious adverse events occurred in either group. However, dyspepsia and skin rashes occurred in six patients (31.58%) in the study group and 13 (65%) in the control group (p = 0.036).

CONCLUSION

Although statistically significant differences were not generated, possibly as a result of the small sample size, mucosal breaks observed via capsule endoscopy revealed that rebamipide was likely to be more effective than lansoprazole in preventing small intestine damage caused by NSAIDs. Furthermore, fewer side-effects emerged with rebamipide.

Prevalence and Characteristics of Dry Eye Disease After Cataract Surgery: A Systematic Review and Meta-Analysis

Dry eye disease (DED) after cataract surgery is associated with various risk factors, while causing a wide range of heterogeneous symptoms including decreased quality of vision. This systematic review and meta-analysis aimed to determine the prevalence and characteristics of DED after cataract surgery. We searched PubMed and EMBASE and included studies on patients with DED after cataract surgery, between January 2011 and June 2020. Study-specific estimates (DED prevalence rates after cataract surgery in patients without preexisting DED) were combined using one-group meta-analysis in a random-effects model. We included 36 studies published between 2013 and 2020. We included nine of these in the meta-analysis of DED prevalence after cataract surgery. Overall 37.4% (95% CI 22.6-52.3; 206/775) of patients without preexisting DED developed DED after cataract surgery. The risk factors for DED after cataract surgery included age, female sex, systemic diseases, systemic medications, psychiatric conditions, preexisting DED, meibomian gland dysfunction, preservatives in eye drops, surgery techniques, and lifestyle. DED severity peak occurred 1 day postoperatively and persisted for at least 1-12 months following cataract surgery; therefore, consistent follow-up for DED is warranted for at least 1 month after cataract surgery. Topical administration of preservative-free diquafosol tetrasodium solution and preoperative meibomian gland treatment were effective in preventing and treating DED following cataract surgery. As more than one-third of patients develop DED after cataract surgery, careful DED management and treatment is needed after cataract surgery to improve satisfaction and vision quality.

Preventive effect of rebamipide on NSAID-induced lower gastrointestinal tract injury using FAERS and JADER

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for their antipyretic, analgesic, and anti-inflammatory properties. However, various aspects of NSAID-induced lower gastrointestinal tract injury remain unclear, and effective prophylaxis has not been established. Based on its pharmacological effect and clinical trials, rebamipide may prevent lower gastrointestinal tract injury, although this evidence is limited by the small scale of trials. The present study used the FDA Adverse Event Reporting System (FAERS) and the Japanese Adverse Event Reporting Database (JADER) to assess the efficacy of rebamipide in combination with loxoprofen and diclofenac in preventing NSAID-induced lower gastrointestinal tract injury. The calculated reporting odds ratio and 95% confidence interval (CI) for rebamipide in combination with loxoprofen and diclofenac were 1.15 (95% CI 0.88–1.51) and 1.28 (95% CI 0.82–2.01) for FAERS, and 0.50 (95% CI 0.35–0.71) and 0.43 (95% CI 0.27–0.67) for JADER, respectively. No signal was detected when combining drugs. These results suggest a prophylactic effect of rebamipide on NSAID-induced lower gastrointestinal tract injury.

Engineering a Remedy to Modulate and Optimize Biopharmaceutical Properties of Rebamipide by Synthesizing New Cocrystal: In Silico and Experimental Studies

PURPOSE

Rebamipide (REB) a potent anti-ulcer agent, has not been exploited to its full potential, owing to it extremely poor solubility, leading to highly diminutive bioavailability (<10%). The purpose is to carry out its solid-state modification.

METHOD

Cocrystallisation was done with three GRAS coformers namely citric acid (CA), 3,4-dihydroxybenzoic acid (DHBA) and oxalic acid (OXA) employing the liquid-assisted grinding method. Cocrystal formation was based upon amide-carboxyl and amide-hydroxyl supramolecular synthons. Characterization of novel cocrystals i.e. RCA, RDHBA and ROXA was carried out by DSC, PXRD and additionally by FT-IR spectroscopy. Chemical structures have been determined utilizing the PXRD pattern by Material Studio®. Furthermore, cocrystals were subjected to solubility and intrinsic dissolution rate (IDR) evaluation. Also, pharmacodynamic and pharmacokinetic studies were performed and compared with pure rebamipide.

RESULT

The appearances of a single sharp melting endotherm in DSC, along with novel characteristic peaks in PXRD infer the existence of a new crystalline form. Shifting in characteristic vibrations in FT-IR spectroscopy supports the establishment of distinct hydrogen-bonded networks. Structural determination revealed that RCA crystallizes in 'Bb2b' space groups whereas RDHBA in 'P1' and ROXA crystallize out in the 'P-1' space group. All the cocrystals exhibited superior apparent solubility and almost 7-13 folds increase in IDR. Furthermore, 1.6-2.5 folds enhancement in relative bioavailability and remarkable amplification in anti-ulcer, anti-inflammatory and the antioxidant potential of these cocrystals were observed.

CONCLUSION

The study ascertains the advantages of cocrystallization, with RCA showing greatest potential and suggests a viable alternative approach for improved formulation of rebamipide.

Potential Strategies in the Prevention of Nonsteroidal Anti-inflammatory Drugs-Associated Adverse Effects in the Lower Gastrointestinal Tract

With the increasing use of nonsteroidal anti-inflammatory drugs (NSAIDs), the incidence of lower gastrointestinal (GI) complications is expected to increase. However, unlike upper GI complications, the burden, pathogenesis, prevention and treatment of NSAID-associated lower GI complications remain unclear. To date, no cost-effective and safe protective agent has been developed that can completely prevent or treat NSAID-related lower GI injuries. Selective COX-2 inhibitors, misoprostol, intestinal microbiota modulation, and some mucoprotective agents have been reported to show protective effects on NSAID-induced lower GI injuries. This review aims to provide an overview of the current evidence on the prevention of NSAID-related lower GI injuries.

Rebamipide with Proton Pump Inhibitors (PPIs) versus PPIs Alone for the Treatment of Endoscopic Submucosal Dissection-Induced Ulcers: A Meta-analysis

Objective

To contrast the effect of rebamipide with proton pump inhibitors (PPIs) versus PPIs alone for the treatment of endoscopic submucosal dissection (ESD-) induced ulcers.

Methods

PubMed, Embase, the Cochrane library, the WanFang database, and China National Knowledge Infrastructure (CNKI) were searched to identify studies that met the inclusion criteria.

Results

Nine randomized controlled trials (RCTs) were recognized, including 1170 patients. In general, rebamipide plus PPIs acted better than PPIs alone against ESD-induced ulcers at four weeks (RR = 1.42, 95% CI: 1.13-1.78, P = 0.003) but showed no significant differences at eight weeks (RR = 1.03, 95% CI: 0.97-1.10, P = 0.315). The use of rebamipide plus PPIs was superior to PPIs alone for ESD-induced ulcers greater than 20 mm in size (20-40 mm: RR = 1.98, 95% CI: 1.22-3.23, P = 0.006; >40 mm: RR = 5.14, 95% CI: 1.49-17.74, P = 0.010). In addition, rebamipide plus PPI therapy was discovered to be significantly more effective than PPIs alone for lower ESD-induced ulcers (RR = 1.82, 95% CI: 1.04-3.20, P = 0.037). There were no significant differences between the treatment groups with the ulcer reduction rate.

Conclusion

Evidences now available show rebamipide plus PPIs is practical for protecting against ESD-induced ulcers at four weeks but not at eight weeks, especially large ulcers (>20 mm). However, we still need more high-quality RCTs in the future to supplement our conclusions.

Hepatoprotective effect of rebamipide against methotrexate-induced hepatic intoxication: role of Nrf2/GSK-3β, NF-κβ-p65/JAK1/STAT3, and PUMA/Bax/Bcl-2 signaling pathways

OBJECTIVES

The fact that methotrexate (MTX) is hepatotoxic is an important reason to limit its clinical use. Rebamipide (REB) has antioxidant and anti-inflammatory properties and is useful for the treatment of gastro-duodenal ulcers. This study investigated the impact and protective mechanisms of REB against MTX-induced hepatotoxicity in rats.

MATERIALS AND METHODS

Animals were divided into four groups of six rats each: a control group, REB group (REB 100 mg/kg/day, orally), MTX control group (20 mg/kg, single i.p.), and MTX + REB group.

RESULTS

The administration of MTX induced marked hepatic injury in the form of hepatocyte inflammatory swelling, degeneration, apoptosis, and focal necrosis. In parallel, our biochemical investigations revealed a marked hepatic dysfunction associated with the disturbance of the oxidant/antioxidant balance in the group treated with only MTX. Moreover, MTX led to the down-regulation of the hepatic Nrf2 and Bcl-2 expressions along with a marked elevation in the hepatic NF-κβ-p65, GSK-3β, JAK1, STAT3, PUMA, and Bax expressions. On the other hand, co-treatment with REB significantly ameliorated the aforementioned histopathological, biochemical, and molecular defects caused by MTX treatment.

CONCLUSION

the outcomes of the present study showed REB's ability to protect from hepatic injury induced by MTX, possibly through its antioxidant, anti-inflammatory, and anti-apoptotic properties. These effects could be attributed to REB's ability to modulate, at least in part, the Nrf2/GSK-3β,NF-κβ-p65/JAK1/STAT3, and PUMA/Bax/Bcl-2signaling pathways.

Biopharmaceutical characterization of rebamipide: The role of mucus binding in regional-dependent intestinal permeability

In this study, we aimed to elucidate biopharmaceutical characteristics of the anti-ulcer drug rebamipide, with special emphasis on the influence of gastrointestinal (GI) mucus on rebamipide segmental-dependent permeability and absorption. Experimental studies and physiologically-based pharmacokinetic (GastroPlus^TM) simulations were used to elucidate segmental-dependent absorption and pharmacokinetic (PK) profile, accounting for various drug properties, including solubility/dissolution limitations, regional-dependent drug affinity to mucus and membrane permeability, as well as physiological factors such as regional-pH differences along the intestine, thickness and types of mucus, transit time and surface areas. Low permeability and extensive binding to GI mucus were the key modeling features, and accounting for these resulted in good fitting between the predicted and in-vivo PK profiles, validating the ability of the model to pinpoint the underlying mechanisms of rebamipide limited oral bioavailability. Furthermore, the simulations indicated regional-dependent intestinal permeability of rebamipide, with absorption rank order of jejunum>ileum>duodenum>colon, mainly attributable to segmental mucus differences. Food effect simulations indicated somewhat decreased rebamipide absorption in the fed state, in corroboration with previous reports. Since this anti-ulcer drug is currently examined for additional indications, this work provides important input for future development of rebamipide.

Additive Effects of Rebamipide Plus Proton Pump Inhibitors on the Expression of Tight Junction Proteins in a Rat Model of Gastro-Esophageal Reflux Disease

Background/Aims

The aim of this study was to investigate the effects of rebamipide on tight junction proteins in the esophageal mucosa in a rat model of gastroesophageal reflux disease (GERD).

Methods

GERD was created in rats by tying the proximal stomach. The rats were divided into a control group, a proton pump inhibitor (PPI) group, and a PPI plus rebamipide (PPI+R) group. Pantoprazole (5 mg/kg) was administered intraperitoneally to the PPI and PPI+R groups. An additional dose of rebamipide (100 mg/kg) was administered orally to the PPI+R group. Mucosal erosions, epithelial thickness, and leukocyte infiltration into the esophageal mucosa were measured in isolated esophagi 14 days after the procedure. A Western blot analysis was conducted to measure the expression of claudin-1, -3, and -4.

Results

The mean surface area of mucosal erosions, epithelial thickness, and leukocyte infiltration were lower in the PPI group and the PPI+R group than in the control group. Western blot analysis revealed that the expression of claudin-3 and -4 was significantly higher in the PPI+R group than in the control group.

Conclusions

Rebamipide may exert an additive effect in combination with PPI to modify the tight junction proteins of the esophageal mucosa in a rat model of GERD. This treatment might be associated with the relief of GERD symptoms.

[The Efficacy of Rebamipide or Ecabet Sodium Supplementation for Helicobacter pylori Eradication Therapy Compared with Quadruple (Concomitant) Regimen]

Background/Aims

Although some previous studies reported that a treatment combined with mucoprotective agent could improve the eradication rate in dual or triple therapy, there are other reports that question the efficacy of combining these drugs in concomitant therapy (CoCTx). The aim of this study was to investigate the effects of rebamipide or ecabet on the Helicobacter pylori (H. pylori) eradication combined with CoCTx.

Methods

We retrospectively reviewed the medical records of 277 patients with proven H. pylori infection. They were assigned to one of 3 regimens for 10 days, twice daily: (a) CoCTx (n=118): lansoprazole 30 mg, amoxicillin 1 g, metronidazole 500 mg, and clarithromycin 500 mg; (b) CoCTx+rebamipide (100 mg) (n=85); (c) CoCTx+ecabet (1 g) (n=74).

Results

The baseline characteristics were not significantly different. H. pylori eradication rates were 82.2% (97/118) in CoCTx, 90.6% (77/85) in CoCTx+rebamipide, and 89.2% (66/74) in CoCTx+ecabet (p=0.17), which were statistically insignificant. Overall adverse events were more frequently reported in the CoCTx+rebamipide (50.6%. 43/85) and CoCTx+ecabet (44.6%, 33/74) groups than in the CoCTx (32.2%, 38/118) (p = 0.03) group. Drug compliances were not different between three groups (CoCTx: 95.8%, 113/118; CoCT+rebamipide: 92.9%, 79/85; CoCTx+ecabet 98.6%,73/74) (p=0.209). Multivariate analysis showed that the risk of eradication failure was significantly increased with decreased drug compliance (odds ratio 3.52, 95% confidence interval 1.00-12.32; p=0.05).

Conclusions

Addition of these mucoprotective agent was not superior to CoCTx alone for eradicating H. pylori infection with frequent adverse events. Rather, drug compliance is the most related factor affecting the eradication rate. Our data suggest the importance of drug compliance over the drugs used.

Non-steroidal anti-inflammatory drug-induced enteropathy

Non-steroidal anti-inflammatory drugs (NSAIDs) are well known to be associated with serious upper gastrointestinal complications, such as peptic ulcer, bleeding, perforation, and obstruction. Recently, attention has been mainly focused on the small bowel injuries caused by NSAIDs, and new endoscopic techniques such as capsule endoscopy and double balloon endoscopy can help in detecting such injuries. This article reviewed the epidemiology, pathogenesis, clinical manifestations, diagnosis, and treatment of small bowel injuries caused by NSAIDs. Small bowel injures by NSAIDs might occur with a similar frequency and extent as those observed in the upper gastrointestinal tract. The pathogenesis of NSAID-induced enteropathy is complex and not clearly understood. The various lesions observed in the small bowel, including petechiae, reddened folds, loss of villi, erosions, and ulcers can be detected by capsule endoscopy. A drug that could prevent or treat NSAID-induced enteropathy has not yet been developed. Therefore, further investigations should be performed to elucidate the pathogenesis of such enteropathy and develop suitable preventive and treatment strategies.

Conjunctival Goblet Cell Density Following Cataract Surgery With Diclofenac Versus Diclofenac and Rebamipide: A Randomized Trial

PURPOSE

To determine the effects of topical diclofenac or betamethasone with concomitant application of topical rebamipide on the conjunctival goblet cell density in eyes after cataract surgery.

DESIGN

Randomized clinical trial.

PARTICIPANTS

Eighty patients who were scheduled for cataract surgery.

METHODS

Patients were randomized into 4 groups according to the postoperative topical drugs to be given; Group A, diclofenac alone; Group B, diclofenac and rebamipide; Group C, betamethasone alone; and Group D, betamethasone and rebamipide. Impression cytology was performed before and at 1 month after the surgery, and the mean density of goblet cells was determined.

RESULTS

The mean (± SD) density of goblet cells before the surgery in Group A was 257.0 ± 188.7 cells/mm², and it decreased significantly to 86.5 ± 76.7 cells/mm² at 1 month after the surgery (P = .002). In Group B, the goblet cell density was not statistically different between before (238.5 ± 116.6 cells/mm²) and at 1 month after the surgery (211.3 ± 184.4 cells/mm², P = .55). In Groups C and D, the mean density of goblet cells was decreased at 1 month after the surgery, but the decreases were not significant (P = .11 and P = .52, respectively).

CONCLUSION

After cataract surgery with postoperative topical diclofenac, the conjunctival goblet cell density was significantly reduced, and this reduction was blocked by the concomitant use of topical rebamipide. These results suggest that the concomitant use of topical rebamipide with nonsteroidal anti-inflammatory drugs is beneficial, especially in cases with postoperative dry eyes.

The solid state of rebamipide: preparation, characterization, and dissolution

Rebamipide is marketed as a peptic ulcer agent under the trade name Mucosta(R). The objective of this work was to investigate the existence of polymorphs and pseudopolymorphs of rebamipide. Two crystal forms of rebamipide were isolated by recrystallization and characterized by differential thermal analysis (DTA), thermogravimetric analysis (TG), powder X-ray diffractometry, infrared spectrometry, and nuclear magnetic resonance. The DTA curve of Form 1 showed one endothermic peak at 305.2 °C, and that of Form 2 showed one endothermic peak at 307.3 °C. The TG curve of Form 1 showed a single weight loss at 305.2 °C, which corresponded to melting. The TG curve of Form 2 also showed a single weight loss at 307.3 °C, which corresponded to melting. The melting point of Form 2 was higher than that of Form 1. In the dissolution studies in pH 6.8 buffer at 37 ± 0.5 °C, the two crystal forms showed no significant differences in dissolution. After 3 months of storage at 0, 52, and 95% RH, the two crystal forms were not transformed. After milling with a Specamill for 2 h, the two crystal forms were not transformed.

Peptide therapies for ocular surface disturbances based on fibronectin-integrin interactions

The condition of the corneal epithelium is a critical determinant of corneal transparency and clear vision. The corneal epithelium serves as a barrier to protect the eye from external insults, with its smooth surface being essential for its optical properties. Disorders of the corneal epithelium include superficial punctate keratopathy, corneal erosion, and persistent epithelial defects (PEDs). The prompt resolution of these disorders is important for minimization of further damage to the cornea. Currently available treatment modalities for corneal epithelial disorders are based on protection of the ocular surface in order to allow natural healing to proceed. PEDs remain among the most difficult corneal conditions to treat, however. On the basis of characterization of the pathobiology of PEDs at the cell and molecular biological levels, we have strived to develop new modes of treatment for these defects. These treatments rely on two key concepts: provision of a substrate, such as the adhesive glycoprotein fibronectin, for the attachment and migration of corneal epithelial cells, and activation of these cells by biological agents such as the combination of substance P and insulin-like growth factor-1 (IGF-1). Central to both approaches is the role of the fibronectin-integrin system in corneal epithelial wound healing. Determination of the minimum amino acid sequences required for the promotion of corneal epithelial wound closure by fibronectin (PHSRN) and by substance P (FGLM-amide) plus IGF-1 (SSSR) has led to the development of peptide eyedrops for the treatment of PEDs that are free of adverse effects of the parent molecules.

Preventive effect of rebamipide on N-methyl-N'-nitro-N-nitrosoguanidine-induced gastric carcinogenesis in rats

Chemoprevention strategies against gastric cancer (GC) need to be explored in light of the fact that stomach cancer still occurs in the absence of Helicobacter pylori (HP) infection and following HP eradication. We evaluated the effect of rebamipide on N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced carcinogenesis in SD rats. Thirty-nine male rats were divided into four groups based on whether or not they were treated with rebamipide and/or MNNG: Control, Rebamipide, Control-M, and Rebamipide-M groups. From 8 weeks of age, rats in the Control-M and Rebamipide-M groups received MNNG in drinking water for 30 weeks. The Rebamipide and Rebamipide-M groups were administered 5mg/kg/day of rebamipide. At 50 weeks, cancerous lesions were not observed in either the Control or Rebamipide groups. Nine rats in the Control-M group had developed GC, while four rats in the Rebamipide-M group had developed GC. The incidence of cancer in the Rebamipide-M group was significantly less than in the Control-M group (p<0.05), with a trend toward a lower incidence of invasive carcinoma in the Rebamipide-M group. Carcinomatous invasion into the muscularis propria was not observed in the Rebamipide-M group. In conclusion, the present study demonstrates that rebamipide suppresses. MNNG-induced carcinogenesis and may also inhibit progression of cancer in rats.

Pharmacokinetic interactions between rebamipide and selected nonsteroidal anti-inflammatory drugs in rats

Nonsteroidal anti-inflammatory drugs (NSAIDs) cause gastrointestinal and renal side effects. Rebamipide is a mucoprotective agent that reduces gastrointenstinal side effects when administered concomitantly with NSAIDs. In this study, we investigated the pharmacokinetic drug interactions of rebamipide with two selected NSAIDs, celecoxib or diclofenac. Rats were randomly divided into five groups. Two groups received placebo and three groups were administered rebamipide (30 mg/kg) orally twice daily for two days. On day 3, the animals treated with placebo received celecoxib (40 mg/kg) or diclofenac (10mg/kg) and rats receiving rebamipide were administerd rebamipide followed by a single dose of placebo, celecoxib, or diclofenac. To investigate drug protein interactions, blank rat plasma was spiked with known concentrations of rebamipide, diclofenac plus rebamipide, or celecoxib plus rebamipide then dialyzed through a Rapid Equilibrium Dialysis device. AUC (139.70±24.97 μg h/mL), Cmax (42.99±2.98 μg/mL), and CLoral (0.08±0.02 L/h/kg) values of diclofenac in diclofenac plus rebamipide group altered when compared to those of diclofenac treated groups. Treatment with rebamipide showed no significant change in pharmacokinetic parameters of celecoxib treated rats. Cmax (7.80±1.22 μg/mL), AUC (56.46±7.30 μg h/mL), Vd/F (7.55±1.37 L/kg), and CLoral (0.58±0.09 L/h/kg) of rebamipide were significantly altered when diclofenac was co-administered with rebamipide. Pharmacokinetic parameters of rebamipide plus celecoxib group were not significantly different from those of rebamipide group. Plasma protein binding was not affected by concomitant administration of another drug. These results indicate alteration of pharmacokinetic parameters of both rebamipide and diclofenac when co-administered and cannot be explained by a variation in plasma protein binding.

European League against rheumatism - selected presentation and poster a highlights June 11th to 13th 2013

INTRODUCTION

The heterogeneous pathology of many autoimmune diseases warrants the continual discovery and development of new drugs. Drawing on selected oral presentations and selected poster displays, this article highlights some new developments in the pharmacological validation of molecular targets implicated in inflammatory autoimmune disease and may be of direct importance to scientists working in this field.

AREAS COVERED

This report describes the current state of the pharmacology of selected drugs and targets which may have utility in modulating immune function and autoimmune inflammatory disease.

EXPERT OPINION

Many new molecules are progressing through clinical development for the treatment of rheumatological diseases. The value of the basic nonclinical and clinical research presented is to further pharmacological knowledge of the molecule, better understand the benefit-risk associated with clinical development and to assist in supporting the potential position of a new drug in the current treatment paradigm.

Rebamipide helps defend against nonsteroidal anti-inflammatory drugs induced gastroenteropathy: a systematic review and meta-analysis

BACKGROUND

Gastrointestinal toxicity of nonsteroidal anti-inflammatory drugs (NSAIDs) has been perplexing most clinicians and users of NSAIDs. Rebamipide is increasingly advocated as a candidate option for the prevention of NSAIDs induced gastrointestinal mucosal injury.

AIMS

To assess the efficacy and the safety of rebamipide for the prevention and treatment of NSAID-induced gastroenteropathy.

METHODS

PubMed, Embase, Web of Science, Google Scholar, the Cochrane Library, Japan Science and Technology Information Aggregator, and China Biology Medicine Disc were searched up to December 2011. Randomized controlled trials (RCTs) recruiting subjects with co-prescriptions of NSAIDs and rebamipide were eligible. Efficacy and safety of rebamipide were reevaluated, and dichotomous data were pooled to obtain relative risk (RR) with a 95 % confidence interval. Heterogeneity and publication bias were assessed by the inconsistency index statistic and funnel plot analysis, respectively.

RESULTS

The search identified 338 citations, and 15 RCTs including 965 individuals were eligible. In general, rebamipide acted better than placebo against short-term NSAID-induced gastroduodenal injury. Separate studies showed rebamipide was equal to or not superior to traditional strategies (including PPIs, H2RA and misoprostol treatment). Especially, rebamipide showed a beneficial effect against the small bowel damage (total RR = 2.70, 95 % confidence interval = 1.02-7.16, P = 0.045) when compared with placebo group. The average incidence of adverse events was about 36.1 % (0-70.0 %) but no serious event was recorded.

CONCLUSIONS

Current evidences show rebamipide is effective and safe for defending against NSAID-induced gastroduodenal and lower-gastrointestinal injuries. However, more well-designed trials should be conducted to fully confirm the practical value of rebamipide.

Mechanisms, prevention and clinical implications of nonsteroidal anti-inflammatory drug-enteropathy

This article reviews the latest developments in understanding the pathogenesis, detection and treatment of small intestinal damage and bleeding caused by nonsteroidal anti-inflammatory drugs (NSAIDs). With improvements in the detection of NSAID-induced damage in the small intestine, it is now clear that this injury and the associated bleeding occurs more frequently than that occurring in the stomach and duodenum, and can also be regarded as more dangerous. However, there are no proven-effective therapies for NSAID-enteropathy, and detection remains a challenge, particularly because of the poor correlation between tissue injury and symptoms. Moreover, recent studies suggest that commonly used drugs for protecting the upper gastrointestinal tract (i.e., proton pump inhibitors) can significantly worsen NSAID-induced damage in the small intestine. The pathogenesis of NSAID-enteropathy is complex, but studies in animal models are shedding light on the key factors that contribute to ulceration and bleeding, and are providing clues to the development of effective therapies and prevention strategies. Novel NSAIDs that do not cause small intestinal damage in animal models offer hope for a solution to this serious adverse effect of one of the most widely used classes of drugs.

Quality of ulcer healing in gastrointestinal tract: Its pathophysiology and clinical relevance

In this paper, we review the concept of quality of ulcer healing (QOUH) in the gastrointestinal tract and its role in the ulcer recurrence. In the past, peptic ulcer disease (PUD) has been a chronic disease with a cycle of repeated healing/remission and recurrence. The main etiological factor of PUD is Helicobacter pylori (H. pylori), which is also the cause of ulcer recurrence. However, H. pylori-negative ulcers are present in 12%-20% of patients; they also recur and are on occasion intractable. QOUH focuses on the fact that mucosal and submucosal structures within ulcer scars are incompletely regenerated. Within the scars of healed ulcers, regenerated tissue is immature and with distorted architecture, suggesting poor QOUH. The abnormalities in mucosal regeneration can be the basis for ulcer recurrence. Our studies have shown that persistence of macrophages in the regenerated area plays a key role in ulcer recurrence. Our studies in a rat model of ulcer recurrence have indicated that proinflammatory cytokines trigger activation of macrophages, which in turn produce increased amounts of cytokines and chemokines, which attract neutrophils to the regenerated area. Neutrophils release proteolytic enzymes that destroy the tissue, resulting in ulcer recurrence. Another important factor in poor QOUH can be deficiency of endogenous prostaglandins and a deficiency and/or an imbalance of endogenous growth factors. Topically active mucosal protective and antiulcer drugs promote high QOUH and reduce inflammatory cell infiltration in the ulcer scar. In addition to PUD, the concept of QOUH is likely applicable to inflammatory bowel diseases including Crohn’s disease and ulcerative colitis.

Rebamipide abolishes Helicobacter pylori CagA-induced phospholipase D1 expression via inhibition of NFκB and suppresses invasion of gastric cancer cells

Infection with cagA-positive Helicobacter pylori is a risk factor for the development of severe gastritis and gastric cancer (GC). CagA protein is injected into gastric epithelial cells and deregulates a variety of cellular signaling molecules. Phospholipase D (PLD) is elevated in many different types of human cancers and has been implicated as a critical factor in inflammation and carcinogenesis. In this study, we show that infection with cagA-positive H. pylori in GC cells significantly induces PLD1 expression via CagA-dependent activation of nuclear factor κB (NFκB). Interestingly, the level of PLD1 protein and IκBα phosphorylation is aberrantly upregulated in H. pylori-infected human GC tissues. Infection with cagA-positive H. pylori and expression of CagA enhanced the binding of NFκB to the PLD1 promoter, and two functional NFκB-binding sites were identified within the PLD1 promoter. Rebamipide, a mucosal-protective antiulcer agent, abolished H. pylori cagA-induced PLD1 expression via inhibition of binding of NFκB to the PLD1 promoter, and also inhibited PLD activity. Moreover, rebamipide suppressed H. pylori-induced matrix metalloproteinase-9, interleukin-8 and activation-induced cytidine deaminase expression as well as invasion of GC cells through downregulation of PLD1. Our data suggest that H. pylori cagA targets PLD1 for invasion of GC cells, and rebamipide might contribute to the antitumorigenic effect of GC cells via inhibition of the H. pylori cagA-NFκB-PLD1 signaling pathway.

Aspirin-induced small bowel injuries and the preventive effect of rebamipide

AIM: To evaluate the influence of taking low-dose aspirin for 4 wk on small intestinal complications and to examine the preventive effect of rebamipide.

METHODS: This study was conducted as a single-center, randomized, double-blind, cross-over, placebo-controlled study. Eleven healthy male subjects were enrolled. Each subject underwent video capsule endoscopy after 1 and 4 wk of taking aspirin and omeprazole, along with either rebamipide or placebo therapy. The primary endpoint was to evaluate small bowel damage in healthy subjects before and after taking low-dose aspirin for 4 wk.

RESULTS: The number of subjects with mucosal breaks (defined as multiple erosions and/or ulcers) were 1 at 1 wk and 1 at 4 wk on the jejunum, and 6 at 1 wk (P = 0.0061) and 7 at 4 wk on the ileum (P = 0.0019). Rebamipide significantly prevented mucosal breaks on the ileum compared with the placebo group (P = 0.0173 at 1 wk and P = 0.0266 at 4 wk).

CONCLUSION: Longer-term, low-dose aspirin administration induced damage in the small bowel. Rebamipide prevented this damage, and may be a candidate drug for treating aspirin-induced small bowel complications.

Prevention and management of non-steroidal anti-inflammatory drugs-induced small intestinal injury

Non-steroidal anti-inflammatory drug (NSAID)-induced small bowel injury is a topic that deserves attention since the advent of capsule endoscopy and balloon enteroscopy. NSAID enteropathy is common and is mostly asymptomatic. However, massive bleeding, stricture, or perforation may occur. The pathogenesis of small intestine injury by NSAIDs is complex and different from that of the upper gastrointestinal tract. No drug has yet been developed that can completely prevent or treat NSAID enteropathy. Therefore, a long-term randomized study in chronic NSAID users is needed.

Comparison of Prevention of NSAID-Induced Gastrointestinal Complications by Rebamipide and Misoprostol: A Randomized, Multicenter, Controlled Trial-STORM STUDY

Nonsteroidal anti-inflammatory drugs (NSAIDs) have gastrointestinal side effects such as dyspepsia, peptic ulcer, hemorrhage, and perforation. Misoprostol and PPIs have been used to prevent NSAID-induced gastroduodenal injury. Rebamipide increases gastric mucus and stimulates the production of endogenous prostaglandins. The prophylactic effect of rebamipide on NSAID-induced gastrointestinal complications is unknown. The aim of this study was to compare NSAID-induced gastrointestinal complications in rebamipide- and misoprostol-treated groups. Patients were randomized to two groups and took a conventional NSAID plus rebamipide or misoprostol for 12 weeks. Gastric mucosal damage was evaluated by endoscopy at screening and the end of the study. The prevalences of active gastric ulcer were 7/176 (3.9%) in the rebamipide group and 3/156 (1.9%) in the misoprostol group. The prevalences of peptic ulcer were 8/176 (4.5%) in the rebamipide group and 7/156 (4.4%) in the misoprostol group. The cumulative incidences of peptic ulcer in the high-risk subgroup were 6/151 (4.0%) for rebamipide and 6/154 (3.9%) for misoprostol. In conclusion, rebamipide prevented NSAID-induced peptic ulcer as effectively as misoprostol in patients on long-term NSAID therapy. Rebamipide may be a useful therapeutic option for the prevention of NSAID-induced gastrointestinal ulcer because of its therapeutic effect and safety.

Treating ocular surface disease: new agents in development

This paper reviews recent advances and investigation in the treatment of ocular surface pathology. There is significant investment in this area, paralleling the growing demand for more effective alternatives to current treatments. Clinicians are becoming more aware of surface pathology, yet the ability to treat the most common forms of ocular pathology are still limited to the few medications approved by the US Food and Drug Administration. Medicines and devices currently under investigation are very promising. It is absolutely critical to understand the emerging options and think of their role in the treatment paradigm.

Rebamipide, a mucoprotective drug, inhibits NSAIDs-induced gastric mucosal injury: possible involvement of the downregulation of 15-hydroxyprostaglandin dehydrogenase

Prostaglandin E₂ plays an important role in the maintenance of gastric mucosal integrity. The level of biologically active prostaglandin E₂ in the tissue is regulated by the balanced expression of its synthetic enzymes, such as cyclooxygenase, and its catabolic enzyme, 15-hydroxyprostaglandin dehydrogenase. We examined the effect of rebamipide, a mucoprotective drug, on prostaglandin E₂ production and metabolism in the gastric tissue and its effect on indomethacin-induced gastric mucosal injury in mice. Rebamipide suppressed indomethacin-induced gastric mucosal injury. Suppressive effect of rebamipide on indomethacin-induced gastric mucosal injury was also observed in cyclooxygenase-2-knockout mice. The mice that were treated with rebamipide showed a 2-fold increase in cyclooxygenase-2 mRNA expression in the gastric tissue, whereas 15-hydroxyprostaglandin dehydrogenase mRNA expression markedly decreased as compared to vehicle-treated control mice. Rebamipide did not affect the expression of cyclooxygenase-1 in the gastric tissue. Rebamipide did not increase prostaglandin E₂ production in the gastric tissue; however, it induced a 1.4-fold increase in the concentration of prostaglandin E₂ in the gastric tissue as compared to vehicle-treated control mice. These results suggest that the suppressive effect of rebamipide on non-steroidal anti-inflammatory drugs-induced gastric mucosal injury can be attributed to reduced 15-hydroxyprostaglandin dehydrogenase expression, which increases the prostaglandin E₂ concentration in the gastric tissue.

Evaluation of small bowel blood flow in healthy subjects receiving low-dose aspirin

AIM: To investigate the relationship between low-dose aspirin-induced small bowel mucosal damage and blood flow, and the effect of rebamipide.

METHODS: Ten healthy volunteers were enrolled in this study. The subjects were divided into two groups: a placebo group given low-dose aspirin plus placebo and a rebamipide group given low-dose aspirin plus rebamipide for a period of 14 d. Capsule endoscopy and contrast-enhanced ultrasonography were performed before and after administration of drugs. Areas under the curves and peak value of time-intensity curve were calculated.

RESULTS: Absolute differences in areas under the curves were -1102.5 (95% CI: -1980.3 to -224.7, P = 0.0194) in the placebo group and -152.7 (95% CI: -1604.2 to 641.6, P = 0.8172) in the rebamipide group. Peak values of time intensity curves were -148.0 (95% CI: -269.4 to -26.2, P = 0.0225) in the placebo group and 28.3 (95% CI: -269.0 to 325.6, P = 0.8343) in the rebamipide group. Capsule endoscopy showed mucosal breaks only in the placebo group.

CONCLUSION: Short-term administration of low-dose aspirin is associated with small bowel injuries and blood flow.

Rebamipide has the potential to reduce the intensity of NSAID-induced small intestinal injury: a double-blind, randomized, controlled trial evaluated by capsule endoscopy

BACKGROUND

A study reported that rebamipide was effective at reducing short-term nonsteroidal anti-inflammatory drug (NSAID)-induced enteropathy. The purpose of this study was to re-evaluate the effect of the co-administration of rebamipide on small intestinal injuries induced by short-term NSAID treatment.

METHODS

Eighty healthy male volunteers were randomly assigned to two study groups: a control group (N = 40), which received NSAID (diclofenac sodium, 75 mg/day) and omeprazole (20 mg/day) treatment along with a placebo; and a rebamipide group, which received NSAID, omeprazole and rebamipide (300 mg/day). Small intestinal injuries (mucosal breaks plus denuded areas) were evaluated by capsule endoscopy before and after 14 days of treatment.

RESULTS

A total of 38 control subjects and 34 rebamipide subjects completed the treatment and were evaluated by capsule endoscopy. NSAID therapy increased the mean number of mucosal injuries per subject from a basal level of 0.1 ± 0.3 to 16 ± 71 and 4.2 ± 7.8 in the control and rebamipide groups, respectively, but the difference was not significant. The difference in the percentage of subjects with at least one mucosal injury post-treatment was also not significant (control 63%; rebamipide 47%). Limiting our analysis to subjects with mucosal injuries, rebamipide co-treatment had the tendency to reduce the mean number of mucosal injuries per subject from 25 in the control group to 8.9 in the rebamipide group (multiple comparisons test; p = 0.088, Mann-Whitney U test; p = 0.038).

CONCLUSIONS

Rebamipide co-therapy had the potential to reduce the intensity of small intestinal injury induced by 2-week administration of diclofenac.

Successful treatment for pouchitis with rebamipide refractory to a combination of metronidazole (MNZ) and ciprofloxacin (CFX)

A 35-year-old male who had undergone proctocolectomy and ileo-anal pouch surgery (IPAA) because of ulcerative colitis presented with worsening diarrhea and hematochezia. Pouchitis was diagnosed, and he was prescribed with metronidazole (MNZ) and a betamethasone enema. However, his condition did not remarkably improve despite these strategies. Endoscopy revealed ulceration and inflammation in the ileal pouch together with contact bleeding and mucous discharge. He underwent granulocytapheresis (G-CAP) and was prescribed anal 5-aminosalicylic acid (5-ASA) and oral prednisolone. Oral azathioprine (AZA) and a combination of MNZ and ciprofloxacin (CFX) did not result in any improvement. He was then treated with rebamipide enemas twice daily for 8 weeks without additional drug therapy. Two weeks thereafter, stool frequency started to decrease, fecal hemoglobin became negative, and his symptoms gradually improved. Endoscopic findings after the rebamipide therapy showed that the ulcers in the ileal pouch had mostly healed without obvious inflammation and bleeding. Rebamipide was thus maintained throughout the therapeutic period and for 13 months of follow-up. Rebamipide effectively treated severe pouchitis that was refractory to intensive conventional medication including antibiotics and corticosteroids.

Efficacy of rebamipide for diclofenac-induced small-intestinal mucosal injuries in healthy subjects: a prospective, randomized, double-blinded, placebo-controlled, cross-over study

BACKGROUND

Although obscure gastrointestinal bleeding cannot be detected by colonoscopy or upper endoscopy, wireless video capsule endoscopy (VCE) is capable of imaging it. Few data are available on medical therapy for patients with nonsteroidal anti-inflammatory drug (NSAID)-induced small-intestinal mucosal injuries. The aim of this study was to compare prevention by rebamipide and placebo of NSAID-induced smallintestinal injury in healthy subjects.

METHODS

Ten healthy subjects who provided written informed consent were enrolled. Rebamipide or placebo plus diclofenac was administered with omeprazole for 7 days, and for an additional 7-day period with treatments reversed in the same subjects, with a 4-week washout period between treatments. VCE of the small intestine was performed four times, before and after each of the two study periods.

RESULTS

The number of subjects with small-intestinal mucosal injuries was higher in the placebo group (8/10) than in the rebamipide group (2/10) (P = 0.023). Two cases of ulcer and one of bleeding were observed in the placebo group, while no ulcer or bleeding was observed in the rebamipide group.

CONCLUSIONS

Rebamipide had significantly higher efficacy than placebo in preventing NSAID-induced small-intestinal mucosal injury.

Rebampide enema therapy as a treatment for patients with chronic radiation proctitis: initial treatment or when other methods of conservative management have failed

INTRODUCTION

Radiation proctitis is a common complication following radiation therapy for pelvic malignancies. There have been no formal trials of treatment for radiation proctitis and a variety of methods are currently used. We assessed the efficacy of rebamipide enema to control symptoms and proctoscopic findings from radiation proctitis.

MATERIALS AND METHODS

Fifteen patients with radiation proctitis were enrolled. Enemas containing 150 mg rebamipide per dosing were administered after morning bowel movement, and always prior to bedtime, twice daily for 4 weeks. The efficacy of treatment was assessed from clinical symptoms (Subjective Objective Management Analysis Scale for Rectal Toxicity) and endoscopic findings.

RESULTS

The mean bleeding score improved from 2.67 to 0.53 (P < 0.01). The mean symptom scores improved in those patients who had pain (0.40 to 0.13), tenesmus (0.40 to 0.20), and stool frequency (0.27 to 0.13). The mean improvement in telangiectasia scores (2.13 to 0.80, P < 0.01), bleeding point scores (1.80 to 0.27, P < 0.01), and friable mucosa scores (1.33 to 0.20, P < 0.01) were all statistically significant. No side effects were noted in any patients.

CONCLUSION

Rebamipide enema therapy for radiation proctitis is a safe and effective treatment of radiation proctitis. We suggest the value of rebamipide enema in the treatment of radiation proctitis when other conservative management or first treatment has failed.

Rebamipide inhibits gastric cancer cell growth

Rebamipide is an antiulcer drug used in Japan, Korea, China, Philippines, and other Asian countries for treatment of gastritis and peptic ulcer. Its effect on gastric cancer cell growth and its regulatory mechanisms remain unknown. We examined whether rebamipide affects human gastric cancer cell proliferation and activation of Smad signaling pathway. Gastric cancer (AGS) cells were treated with either (a) medium (control), (b) medium-containing rebamipide (0.5-2 mg/mL), or (c) PD98059+rebamipide. We determined cell proliferation, expression of p21, phosphorylation of ERK2, JNK p38, and Smad2/3, formation of Smad2/3-Smad4 complex, and nuclear translocation of Smad2/3. Rebamipide treatment inhibited AGS cell proliferation and increased p21, Smad2/3 phosphorylation, and Smad2/3-Smad4 complex formation. Rebamipide induced phosphorylation of ERK2 but not JNK or p38. Inactivation of ERK2 by PD98059 partly attenuated rebamipide-induced p21 expression. These data demonstrate that rebamipide activates Smad signaling pathway and suppresses human gastric cancer cell growth. Inactivation of ERK2 partly inhibited rebamipide-induced p21 expression, indicating a crosstalk between ERK and Smad signaling pathways.

Successful treatment of severe pouchitis with rebamipide refractory to antibiotics and corticosteroids: A case report

The antibiotics, metronidazole and ciprofloxacin, are the first-line treatment for pouchitis. Patients who do not respond to antibiotics or conventional medications represent a major challenge to therapy. In this report, we have described a successful treatment of severe refractory pouchitis with a novel agent, rebamipide, known to promote epithelial cell regeneration and angiogenesis. A 27-year-old male with ileo-anal pouch surgery presented with worsening anal pain, diarrhea, and abdominal pain. The patient was diagnosed to have pouchitis and was given metronidazole together with betamethasone enema (3.95 mg/dose). However, despite this intensive therapy, the patient did not improve. On endoscopy, ulceration and inflammation were seen in the ileal pouch together with contact bleeding and mucous discharge. The patient was treated with rebamipide enema (150 mg/dose) twice a day for 8 wk without additional drug therapy. Two weeks after the rebamipide therapy, stool frequency started to decrease and fecal hemoglobin became negative at the 4^th wk. At the end of the therapy, endoscopy revealed that ulcers in the ileal pouch had healed with no obvious inflammation. The effect of rebamipide enema was dramatic and was maintained throughout the 11-mo follow-up. The patient continued to be in remission. No adverse effects were observed during the treatment or the follow-up period. The sustained response seen in this case with severe and refractory pouchitis indicates that agents, which promote epithelial cell growth, angiogenesis and mucosal tissue regeneration, are potential therapeutic agents for the treatment of refractory colorectal lesions.

Efficacy of rebamipide enemas in active distal ulcerative colitis and proctitis: a prospective study report

Rebamipide has a broad spectrum of pharmacological actions that include suppression of neutrophil functions and stimulation of mucosal epithelial cell regeneration by increasing the expression of epithelial growth factor (EGF) and the EGF receptor. Sixteen patients with active ulcerative colitis (UC; mild in 1 patient, moderate in 11, and severe in 4) were recruited. Enemas containing 150 mg rebamipide per dosing were administered during the daytime after passage of stool, twice a day for 4 weeks. UC disease activity index (UC-DAI), endoscopic activity index (EAI), and Floren's grading (FG) of mucosal biopsy specimens were measured at entry and at 4 weeks. Five of 16 patients did not complete the study, and therefore, final efficacy assessment was done on 11 patients who completed the 4 weeks of treatment. Improvements were observed in UC-DAI (P = 0.0049), EAI (P = 0.0043), and FG (P = 0.0084). There was no serious rebamipide-related side effect in any of the 16 patients. In conclusion, rebamipide topical therapy appears to be effective for the treatment of mildly to moderately active distal UC. Further controlled studies are warranted for this promising drug.

An overview of acetic acid ulcer models--the history and state of the art of peptic ulcer research

Four types of experimental chronic ulcer models, named acetic acid ulcer models, have been developed to examine the healing process of peptic ulcers, screen anti-ulcer drugs, and better evaluate the adverse effects of various anti-inflammatory drugs on the gastrointestinal mucosa. The model easily and reliably produces round, deep ulcers in the stomach and duodenum, allowing acetic acid ulcer production in mice, rats, Mongolian gerbils, guinea pigs, cats, dogs, miniature pigs, and monkeys. These ulcer models highly resemble human ulcers in terms of both pathological features and healing process. The models have been established over the past 35 years and are now used throughout the world by basic and clinical scientists. One of the characteristic features of acetic acid ulcers in rats is the spontaneous relapse of healed ulcers >100 d after ulceration, an endoscopically confirmed phenomenon. Indomethacin significantly delays the healing of acetic acid ulcers, probably by reducing endogenous prostaglandins and inhibiting angiogenesis in ulcerated tissue. Helicobacter pylori significantly delays healing of acetic acid ulcers and causes relapse of healed ulcers at a high incidence in Mongolian gerbils. Anti-secretory drugs (e.g. omeprazole), prostaglandin analogs, mucosal defense agents (e.g. sucralfate), and various growth factors all significantly enhance healing of acetic acid ulcers. Gene therapy with epidermal growth factor and vascular endothelial growth factor applied to the base of acetic acid ulcers in rats is effective in enhancing ulcer healing. Since an inhibitor of nitric oxide syntase prevents ulcer healing, nitric oxide might be involved in the mechanism underlying ulcer healing. We conclude that acetic acid ulcer models are quite useful for various studies related to peptic ulcers.

Gastro-protective agent rebamipide induces cyclooxygenease-2 (COX-2) in gastric epithelial cells

Cyclooxyngease-2 (COX-2) is a key enzyme in prostaglandin (PG) synthesis, and COX-2 induction plays an important role in the healing of gastric ulceration. Rebamipide is a gastro-protective agent and attenuates the activity of neutrophils. A number of reports have shown that rebamipide treatment increases PG production in the gastric mucosa {in vivo}. Although its clinical significance in ulcer healing has been demonstrated, {in vitro} evidence remains to be accumulated. Non-transformed rat gastric mucosal cells (RGM1 cells) were stimulated with rebamipide. RT-PCR and Western blot analysis revealed time and dose-dependent transcriptional and translational stimulation of COX-2. PGE(2) was also produced dose-dependently. However, marked COX-2 induction by rebamipide was transient and lasted less than 24 hr. COX-1 expression was unaltered by rebamipide. Reporter assay results confirmed the stimulation of Cox-2 promoter activity by rebamipide. In conclusion, this study provides {in vitro} evidence that rebamipide transcriptionally induces COX-2 and supports the rationale for its clinical use.

Rebamipide reduces recurrence of experimental gastric ulcers: role of free radicals and neutrophils

Mucosal inflammation is a crucial factor for the recurrence of peptic ulcer. In this study, we examined the effect of rebamipide on neutrophils infiltration, lipid peroxidation, and antioxidative enzyme activities in the recurrence of experimental gastric ulcer. Ulcer recurrence was examined at 60, 100, and 140 days after production of acetic acid-induced gastric ulcers in rats. Gastric neutrophil infiltration, lipid peroxidation, and antioxidative enzyme activities were determined by analyses of myeloperoxidase (MPO) activity, thiobarbituric acid reactive substance (TBARS) levels, and glutathione peroxidase (GSHpx) and superoxide dismutase (SOD) activities in the ulcer region, respectively. The effect of rebamipide, an antigastric-ulcer agent, on ulcer recurrence was assessed following oral administration at 60 mg/kg/day from day 20. In the control and rebamipide groups, gastric ulcer indices were reduced on day 100 compared with day 60; however, increases were observed on day 140, indicating ulcer recurrence. In the rebamipide group, the ulcer index was smaller than in the control group at each time point and the effect was significant on day 140. Although marked elevation of MPO activities was observed in the control group during the experiment, no significant elevations were seen in the rebamipide group on days 100 and 140. TBARS levels were significantly elevated in the control group on day 140, but not in the rebamipide group. Rebamipide suppressed the decrease in GSHpx activity on day 60. These results suggest that lipid peroxidation of gastric tissue mediated by free radicals from neutrophils is responsible for the recurrence of acetic acid-induced gastric ulcers in rats, and that the elimination of free radicals by rebamipide may contribute to the reduction of severity in ulcer recurrence.

Rebamipide reduces delay in gastric ulcer healing in cyclooxygenase-2-deficient mice

Rebamipide is an antiulcer drug capable of various actions including the induction of cyclooxygenase-2 (COX-2). In this study, we investigated the effect of rebamipide on gastric ulcer healing in COX-2-deficient mice. Wild-type (N=34) and COX-2-deficient mice (N=28) with gastric ulcers were administered 30 mg/kg of rebamipide or the vehicle. Ulcerous tissues were subjected to measurements of ulcer size, immunohistochemical staining of CD31 (an endothelial cell marker), and mRNA levels. COX-2 deficiency delayed ulcer healing and inhibited angiogenesis and bFGF mRNA expression in the granulation tissue. In wild-type mice, rebamipide accelerated ulcer healing and increased COX-2 mRNA expression. In COX-2-deficient mice, rebamipide prevented delayed ulcer healing and reversed the inhibition in angiogenesis and bFGF mRNA expression. The effect of rebamipide on the enhancement of ulcer healing, angiogenesis, and induction of bFGF expression was more prominent in wild-type mice than in COX-2-deficient mice. In conclusion, rebamipide may accelerate gastric ulcer healing through both COX-2-dependent and COX-2-independent mechanisms.

Rebamipide, a gastro-protective drug, inhibits indomethacin-induced apoptosis in cultured rat gastric mucosal cells: association with the inhibition of growth arrest and DNA damage-induced 45 alpha expression

Rebamipide, a gastromucosal protective drug, suppresses indomethacin-induced gastropathy in humans and rodents. Effects of rebamipide on gene expression in indomethacin-treated gastric mucosal cells (RGM1) were investigated using high-density oligonucleotide arrays. Indomethacin induced apoptosis in RGM1 cells in a dose-dependent manner. Rebamipide pretreatment significantly reduced indomethacin-induced apoptosis. We used gene expression profiling on high-density oligonucleotide probe arrays to characterize the transcriptional response of RGM1 cells to indomethacin treatment for 6 hr. Of the 8,799 probes examined, 717 (8.1%) were induced (400 probes) or repressed (317 probes) at least 1.5-fold. Among the 158 genes that were induced by indomethacin at least 2.0-fold, four genes that were down-regulated by rebamipide at least 2.0-fold are listed: growth arrest and DNA-damage-inducible 45 alpha (GADD 45 alpha), golgi SNAP receptor complex member 1, iodothyronine deiodinases, and transcription factor 8. Real time-PCR confirmed GADD 45 alpha expression and its inhibition by rebamipide. Inhibition of apoptosis-related genes is possibly important for the cytoprotective effect of rebamipide against indomethacin-induced gastric mucosal cell injury.

Rebamipide inhibits gastric cancer growth by targeting survivin and Aurora-B

Rebamipide accelerates healing of gastric ulcers and gastritis but its actions on gastric cancer are not known. Survivin, an anti-apoptosis protein, is overexpressed in stem, progenitor, and cancer cells. In gastric cancer, increased and sustained survivin expression provides survival advantage and facilitates tumor progression and resistance to anti-cancer drugs. Aurora-B kinase is essential for chromosome alignment and mitosis progression but surprisingly its role in gastric cancer has not been explored. We examined in human gastric cancer AGS cells: (1) survivin expression, (2) localization of survivin and Aurora-B, (3) cell proliferation, and (4) effects of specific survivin siRNA and/or rebamipide (free radical scavenging drug) on survivin and Aurora-B expression and cell proliferation. Survivin and Aurora-B are strongly expressed in human AGS gastric cancer cells and co-localize during mitosis. Survivin siRNA significantly reduces AGS cell viability. Rebamipide significantly downregulates in AGS cell survivin expression, its association with Aurora-B and cell proliferation. Rebamipide-induced downregulation of survivin is at the transcription level and does not involve ubiquitin-proteasome pathway.

Review article: rebamipide and the digestive epithelial barrier

Rebamipide exerts a positive effect on the digestive epithelial barrier by reinforcing its integrity in normal and in inflammatory conditions, and by normalizing the macromolecular transport across this barrier, increased by Helicobacter infection. Moreover, in mice, rebamipide is capable of diminishing allergic sensitization and of counteracting the inhibitory effect of Helicobacter pylori on oral tolerance to dietary antigens. These properties of rebamipide could explain its anti-inflammatory activity with respect to the digestive mucosa and could provide protection against allergic sensitization to foreign antigens in susceptible individuals.

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.

The effect of rebamipide on the expression of proinflammatory mediators and apoptosis in human neutrophils by Helicobacter pylori water-soluble surface proteins

BACKGROUND

Helicobacter pylori infection elicits persistent neutrophil infiltration in gastric mucosa. The expression of cyclooxygenase (COX)-2 and inhibition of apoptosis in the neutrophils could contribute to the pathogenesis of H. pylori infection. Rebamipide, a mucosal protective and ulcer-healing drug, has been known to inhibit neutrophil activation.

AIM

To evaluate the effect of rebamipide on the neutrophils activated by H. pylori water-soluble proteins.

METHODS

After neutrophils were stimulated with H. pylori water extract (HPWE) or pre-treated with rebamipide, the expression of COX-2 mRNA and protein was assessed by quantitative RT-PCR and Western blotting, respectively. Prostaglandin (PG) E2 synthesis was determined by radioimmunoassay. Neutrophil apoptosis was evaluated by cytosolic oligonucleosome-bound DNA ELISA and caspase-3 activity was measured by the detection of p-nitroanilide after cleavage from labelled substrate.

RESULTS

Stimulation with HPWE up-regulated COX-2 expression and PGE2 secretion, and inhibited neutrophil apoptosis. Rebamipide suppressed PGE2 secretion from neutrophils dose-dependently. Rebamipide, however, did not affect neutrophil apoptosis and caspase-3 activity.

CONCLUSIONS

Rebamipide effectively suppressed PGE2 secretion from neutrophils activated by H. pylori water-soluble proteins. This is another possible mechanism of gastric mucosal protection by rebamipide.

Expression of cyclooxygenase-2 in human neutrophils activated by Helicobacter pylori water-soluble proteins: possible involvement of NF-kappaB and MAP kinase signaling pathway

Helicobacter pylori infection elicits persistent neutrophil infiltration in gastric mucosa. The expression of cyclooxygenase (COX) -2 by the neutrophils results in prostaglandin (PG) E2 synthesis, which may account for alterations in tissue homeostasis. In this study, we found that COX-2 mRNA was up-regulated in the neutrophils when stimulated with both H. pylori water extract (HPWE) and live H. pylori in a transwell model and determined by quantitative RT-PCR. PGE2 synthesis was also enhanced in the neutrophils activated by both the HPWE and live H. pylori. A specific COX-2 inhibitor (NS-398) blocked PGE2 synthesis, and an anti-ulcer agent (rebamipide) suppressed it dose dependently. An NF-kappaB inhibitor (pyrrolidine dithiocarbamate), a MAP kinase (MEK) inhibitor (PD98059), and a p38 MAP kinase inhibitor (SB203580) significantly suppressed the COX-2 gene transcription and PGE2 synthesis in the neutrophils. In conclusion, H. pylori water-soluble proteins may enhance the COX-2 expression, and this action could be mediated through the NF-kappaB and MAP kinase signaling pathways. The increased section of PGE2 by the neutrophils may play a proinflammatory role in the gastric mucosal response to H. pylori.