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 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.     

Healing of duodenal ulcers is not impaired by indomethacin or rofecoxib,the selective COX-2 inhibitor,in rats

BACKGROUND/AIM: Studies have demonstrated an important role for endogenous PG and NO in the healing of chronic gastric ulcers. We investigated the effects of COX and NOS inhibitors on the healing of duodenal ulcers, in comparison with gastric ulcers, in rats. METHODS: Gastric and duodenal ulcers were induced by serosal application of acetic acid (0.1 ml of 100% acetic acid) for 60 and 20 s, respectively. Indomethacin (a nonselective COX inhibitor) or rofecoxib (a selective COX-2 inhibitor) was given p.o. once daily for 14 days from 3 days after ulcer induction, while N(G)-nitro-L-arginine methyl ester (L-NAME: a nonselective NOS inhibitor) or aminoguanidine (a relatively selective iNOS inhibitor) was given s.c. twice daily during this period. RESULTS: Both gastric and duodenal ulcers induced by acetic acid healed spontaneously within 17 days to a minimal size. Daily administration of indomethacin or rofecoxib significantly delayed the healing of gastric but not duodenal ulcers. In contrast, the healing of both gastric and duodenal ulcers was delayed by repeated administration of either L-NAME or aminoguanidine. Ulceration markedly increased the PGE(2) content of the ulcerated mucosa in both the stomach and duodenum, and the increased PG biosynthetic response was inhibited by either indomethacin or rofecoxib in both tissues. The expression of both COX-2 and iNOS mRNAs was upregulated in the ulcerated mucosa of the stomach and duodenum. CONCLUSION: These results suggest that COX-2/PG is actively involved in the healing of gastric but not duodenal ulcers, although the mRNA for COX-2 is expressed in the duodenal mucosa after ulceration, as potently as in the gastric mucosa. In contrast, NO produced by both cNOS and iNOS plays a role in the healing of both gastric and duodenal ulcers.     

Stimulation of prostaglandin biosynthesis mediates gastroprotective effect of rebamipide in rats

The concept that gastroprotection by agents such as mild irritants, antacids, or sucralfate is prostaglandin (PG)-mediated has been challenged recently. These agents do not reproducibly stimulate prostaglandin formation, and indomethacin does not effectively attenuate their protective potency. Rebamipide is a novel antiulcer compound. This study was designed to clarify whether eicosanoids contribute to the gastroprotective activity of the drug. In the rat stomach, rebamipide (100 and 500 mg/kg, intraperitoneally) slightly increased release of PGE₂, 6-keto-PGF₁ thromboxane B₂, and the metabolite 15-keto-13,14-dihydro-PGE₂ from mucosal fragments incubated ex vivo and significantly enhanced secretion of these products into the lumen, resulting in gastric juice eicosanoid levels exceeding those in controls several-fold. Mucosal formation of leukotriene (LT) C₄ was not affected by rebamipide. Rebamipide caused substantial protection against gastric damage produced by ethanol, which was antagonized by pretreatment with indomethacin (0.1–5 mg/kg, subcutaneously). The dose-response relationship of indomethacin for inhibition of prostaglandin formation and rebamipide-induced protection correlated well and 5 mg/kg indomethacin completely prevented the protective effect of rebamipide. The results indicate that: (1) in contrast to most other protective agents, protection by rebamipide involves the endogenous prostaglandin system; (2) the increase in prostaglandin formation results from stimulation of biosynthesis, and not inhibition of degradation; (3) gastroprotection by rebamipide occurs despite increased thromboxane formation and is not associated with reduced generation of LTC₄; and (4) determinations of gastric juice eicosanoids seem to be particularly useful to evaluate effects of agents increasing formation of cyclooxygenase products in the stomach.     

Selective inhibition of inducible cyclooxygenase 2 in vivo is antiinflammatory and nonulcerogenic.

We have examined the role of cyclooxygenase 2 (COX-2) in a model of inflammation in vivo. Carrageenan administration to the subcutaneous rat air pouch induces a rapid inflammatory response characterized by high levels of prostaglandins (PGs) and leukotrienes in the fluid exudate. The time course of the induction of COX-2 mRNA and protein coincided with the production of PGs in the pouch tissue and cellular infiltrate. Carrageenan-induced COX-2 immunoreactivity was localized to macrophages obtained from the fluid exudate as well as to the inner surface layer of cells within the pouch lining. Dexamethasone inhibited both COX-2 expression and PG synthesis in the fluid exudate but failed to inhibit PG synthesis in the stomach. Furthermore, NS-398, a selective COX-2 inhibitor, and indomethacin, a nonselective COX-1/COX-2 inhibitor, blocked proinflammatory PG synthesis in the air pouch. In contrast, only indomethacin blocked gastric PG and, additionally, produced gastric lesions. These results suggest that inhibitors of COX-2 are potent antiinflammatory agents which do not produce the typical side effects (e.g., gastric ulcers) associated with the nonselective, COX-1-directed antiinflammatory drugs.     

Dynamic physiological and molecular changes in gastric ulcer healing achieved by melatonin and its precursor L-tryptophan in rats

Abstract:  Following induction of gastric ulcer in rats by serosal application of acetic acid, local mucosal necrosis ensues accompanied by a reduction in mucosal microcirculation and by almost immediate expression of inducible nitric oxide (NO) synthase (iNOS) and proinflammatory cytokines. Daily application of melatonin (20 mg/kg) or l -tryptophan (100 mg/kg) accelerates ulcer healing by affecting the cyclooxygenase-2 (COX-2)–prostaglandin (PG) system with excessive production of protective PG, especially in later period of ulcer healing. Furthermore, expression of hypoxia inducible factor, vascular-endothelial growth factor, an activation of cNOS–NO system and the stimulation of sensory nerves with the expression and release of calcitonin gene related peptide (CGRP) appear to aid the restoration of mucosal repair and microcirculation in the ulcer bed. The enhanced expression of the melatonin MT₂ receptors (MT₂-R) combined with overexpression of key enzymes involved in biosynthesis of melatonin such as N -acetyltransferase and hydroxyindole- O -methyltransferase contribute to the acceleration of ulcer healing by this indole. Melatonin-induced acceleration of ulcer healing is also mediated by release of gastrin and ghrelin, the most potent stimulants of gastric mucosal cell proliferation and mucosal repair. These sequential steps in ulcer healing accelerated by melatonin can be interfered with by the blockade of MT₂R, COX-2/PG and cNOS/NO systems, and by reduction in the inflammatory iNOS/NO system. Thus, melatonin and its precursor l -tryptophan, trigger the cascade of molecular events leading to the functional improvement in ulcer healing.     

Upregulated Cyclooxygenase-2 Inhibits Apoptosis of Human Gastric Epithelial Cells Infected with Helicobacter pylori

Helicobacter pylori induces apoptosis and alters the proliferation of gastric mucosal epithelial cells. Cyclooxygenase-2 (COX-2), the inducible form of prostaglandin (PG) synthesis, is known to cause alteration in epithelial cell growth. The goal of this study was to determine whether COX-2 gene expression by H. pylori infection could influence gastric epithelial cell apoptosis. Expression of COX-2 mRNA and proteins was up-regulated in Hs746T gastric epithelial cell lines infected with H. pylori, when assessed by quantitative RT-PCR and western blot. Inhibition of COX-2 expression using NS-398, a specific COX-2 inhibitor, showed a significant increase of gastric epithelial cell apoptosis and caspase-3 activation in Hs746T cells infected with H. pylori. Moreover, the effect of NS-398 on H. pylori-induced apoptosis was reversed by the addition of PGE₂. These results suggest that up-regulated COX-2 expression by H. pylori infection can inhibit apoptosis of gastric epithelial cells.     

Pathogenesis of NSAID-induced gastric damage: importance of cyclooxygenase inhibition and gastric hypermotility

This article reviews the pathogenic mechanism of non-steroidal anti-inflammatory drug (NSAID)-induced gastric damage, focusing on the relation between cyclooxygenase (COX) inhibition and various functional events. NSAIDs, such as indomethacin, at a dose that inhibits prostaglandin (PG) production, enhance gastric motility, resulting in an increase in mucosal permeability, neutrophil infiltration and oxyradical production, and eventually producing gastric lesions. These lesions are prevented by pretreatment with PGE₂ and antisecretory drugs, and also via an atropine-sensitive mechanism, not related to antisecretory action. Although neither rofecoxib (a selective COX-2 inhibitor) nor SC-560 (a selective COX-1 inhibitor) alone damages the stomach, the combined administration of these drugs provokes gastric lesions. SC-560, but not rofecoxib, decreases prostaglandin E₂ (PGE₂) production and causes gastric hypermotility and an increase in mucosal permeability. COX-2 mRNA is expressed in the stomach after administration of indomethacin and SC-560 but not rofecoxib. The up-regulation of indomethacin-induced COX-2 expression is prevented by atropine at a dose that inhibits gastric hypermotility. In addition, selective COX-2 inhibitors have deleterious influences on the stomach when COX-2 is overexpressed under various conditions, including adrenalectomy, arthritis, and Helicobacter pylori-infection. In summary, gastric hypermotility plays a primary role in the pathogenesis of NSAID-induced gastric damage, and the response, causally related with PG deficiency due to COX-1 inhibition, occurs prior to other pathogenic events such as increased mucosal permeability; and the ulcerogenic properties of NSAIDs require the inhibition of both COX-1 and COX-2, the inhibition of COX-1 upregulates COX-2 expression in association with gastric hypermotility, and PGs produced by COX-2 counteract the deleterious effect of COX-1 inhibition.     

COX-1 and COX-2 conversely promote and suppress ischemia-reperfusion gastric injury in mice

OBJECTIVE: Neutrophil activation followed by free radical production is a feature that is common to the various forms of gastric injury. However, the roles of cyclooxygenase (COX)-1 and -2 in neutrophil activation have yet to be clarified in the gastric mucosa. We examined the roles of both COX-1 and COX-2 in neutrophil activation and free radical production in ischemia-reperfusion (IR) injury in the gastric mucosa of mice. MATERIAL AND METHODS: Ischemia was induced by clamping the celiac artery for 30 min, then removing the clamp for 90 min. SC-560, a selective COX-1 inhibitor; NS-398, a selective COX-2 inhibitor; or rebamipide, a mucoprotective agent, was administered to mice 60 min before ischemia. Gastric damage was evaluated histologically and by measuring myeloperoxidase (MPO) activity. Expressions of COX protein and intercellular adhesion molecule (ICAM)-1 were evaluated by Western blot analysis and ELISA, respectively. Effects of these drugs on thiobarbituric acid reactive substances (TBARS) and gastric blood flow were also evaluated. RESULTS: COX-2 expression was induced in gastric mucosa 60 min after reperfusion, whereas COX-1 expression remained unaltered. Localization of COX-1 and ICAM-1 in IR-injured mucosa was observed mainly in endothelial cells, while COX-2 expression was detected in mesenchymal cells such as mononuclear cells, spindle-like cells and endothelial cells. SC-560 significantly decreased gastric blood flow at the reperfusion point and reduced gastric mucosal injury in IR mice. Furthermore, SC-560 pretreatment significantly reduced MPO activity, TBARS levels and ICAM-1 expression. In contrast, NS-398 significantly increased ICAM-1 expression, MPO activity and TBARS levels, and aggravated gastric damage in IR mice. Rebamipide pretreatment reduced both COX-2 expression and IR injury. CONCLUSIONS: In IR mice, COX-2 protects the gastric mucosa by down-regulating ICAM-1 expression, whereas COX-1 is involved in up-regulating reperfusion flow, thereby aggravating the mucosa.     

Rebamipide, a gastro-protective and anti-inflammatory drug, promotes gastric ulcer healing following eradication therapy for Helicobacter pylori in a Japanese population: a randomized, double-blind, placebo-controlled trial

Background One week of Helicobacter pylori eradication therapy is insufficient for healing of gastric ulcers. We examined the efficacy of rebamipide in gastric ulcer healing following 1 week of eradication therapy in a randomized, double-blind, placebo-controlled trial. Methods Patients with H. pylori-positive gastric ulcer were enrolled and received 1 week of eradication therapy, followed by 100 mg of rebamipide or placebo for 7 weeks. The primary end point was the gastric ulcer healing rate. Results Of the 309 patients entered in the trial, 301 completed H. pylori eradication therapy; 154 patients took rebamipide, and 147 took placebo. The healing rate in the rebamipide group was higher than that in the placebo group in the per-protocol analysis—80.0% (104/130) versus 66.1% (82/124) [95% confidence interval (CI), 3.1–24.7; P = 0.013)—and in a full analysis—70.1% (108/154) versus 60.5% (89/147) (95% CI, −1.1 to 20.3; P = 0.080). Conclusions Compared with placebo, rebamipide significantly promoted gastric ulcer healing following 1 week of eradication therapy.     

Rebamipide Activates Genes Encoding Angiogenic Growth Factors and Cox2 and Stimulates Angiogenesis: A Key to Its Ulcer Healing Action?

Clinical and experimental data indicate that rebamipide accelerates ulcer healing, improves scar quality, and prevents ulcer recurrence. However, the mechanisms responsible for these rebamipides' actions are not fully elucidated. We studied, using gene expression microarray analysis, which of the ulcer healing genes are activated by rebamipide treatment. Normal rat gastric epithelial cells (RGM1) were treated with either vehicle or rebamipide. Gene expression was determined using Affymetrix rat genome U34A gene chip arrays and data were analyzed using the GeneSpring program. Activation of some of the genes and protein translation were also examined by RT/PCR and Western blotting. Rebamipide significantly upregulated the proangiogenic genes encoding vascular endothelial growth factor (VEGF), by 7.5-fold, heparin binding epidermal growth-like factor (HB-EGF), by approximately 5-fold, fibroblast growth factor receptor-2 (FGFR2), by 4.4-fold, and cyclooxygenase-2 (Cox2), by 9.3-fold, as well as growth promoting genes, e.g., insulin growth factor-1 (IGF-1), by 5-fold. RT/PCR and Western blotting demonstrated that Cox2 mRNA and protein were upregulated; the latter, approximately 6-fold. Treatment of rat gastric mucosal endothelial cells with rebamipide stimulated in vitro angiogenesis by approximately 240% (vs. controls, P < 0.001). Conclusions are as follows. (1) Rebamipide activates in gastric epithelial RGM-1 cells a genetic program that promotes angiogenesis and signals cell growth and tissue regeneration. (2) In addition, rebamipide treatment directly stimulates angiogenesis in gastric microvascular endothelial cells. Thus rebamipide has two separate and distinct mechanisms of proangiogenic action: one through activation in gastric epithelial cells of proangiogenic growth factor genes and the second a direct angiogenic action on microvascular endothelial cells.     

Impairment of Gastric Ulcer Healing by Alendronate,a Nitrogen-Containing Bisphosphonate,in Rats

Bisphosphonates such as alendronate have been developed as antiresorptive agents capable of treating diseases related to bone remodeling. In the present study, we examined the effect of alendronate on the healing of acetic acid-induced gastric ulcers in rats and investigated the mechanism involved in this action both in vivo and in vitro using the rat gastric epithelial cell line (RGM1). Acetic acid-induced gastric ulcers healed spontaneously, with up-regulation of COX-2/prostaglandin E₂ production as well as expression of vascular endothelium-derived growth factor (VEGF) and basic fibroblast growth factor (bFGF) in ulcerated mucosa. The healing of ulcers was impaired by indomethacin (2 mg/kg, s.c.) or alendronate (60 mg/kg, p.o.) given once daily for 7 days, starting 3 days after acid application. Indomethacin, but not alendronate, inhibited mucosal prostaglandin E₂ production. Alendronate as well as indomethacin decreased the protein expression of both VEGF and bFGF in ulcerated mucosa, resulting in a reduction of angiogenesis in the ulcer base. Supplementation of recombinant bFGF significantly reverted the delay in ulcer healing caused by alendronate. On the other hand, the size of cell-free areas in RGM1 cells in vitro decreased with time after wound induction, and this process was promoted by epidermal growth factor (EGF; 10 ng/ml). Co-incubation with alendronate (1 mM) did not affect the spontaneous healing but significantly suppressed the accelerated wound healing caused by EGF. These results suggest that alendronate impairs the healing of gastric ulcers in rats, and this effect may be related to down-regulation of VEGF and bFGF, the important growth factors for vascularization/granulation, as well as suppression of the stimulatory action of EGF on epithelial proliferation/migration.     

Epidermal growth factor,polyamines, and prostaglandins in healing of stress-induced gastric lesions in rats

Previous studies demonstrated that epidermal growth factor (EGF) and polyamines (PA) are capable of protecting gastric mucosa against topical irritants. This study was designed to examine whether EGF, PA, and PG affect the healing of acute gastric lesions induced by water immersion and restraint stress. It was found that the healing process of stress lesions in sham-operated rats was significant after 6 hr after stress, and after 24 hr the number of stress lesions was reduced by about 75%. In sham-operated rats, the healing of ulcerations observed at 6, 12, and 24 hr after the stress was accompanied by gradual restoration of DNA synthesis, and both these processes were significantly reduced by administration of DFMO (an inhibitor of ornithine decarboxylase activity) or indomethacin (an inhibitor of cyclooxygenase). In salivectomized rats, the healing was significantly delayed and the DNA was lowered at all time intervals after the stress. Administration of EGF, spermine, aminoguanidine (an inhibitor of degradation of PA), or 16,16-dmPGE₂ after stress promoted significantly the healing and DNA synthesis, but pretreatment with DFMO abolished the effect of EGF but not that of spermine. We conclude that EGF, PA, and PG are implicated in healing of stress lesions and that EGF acts, at least in part, by the stimulation of PA formation in the gastric mucosa.     

Effect of local application of growth factors on gastric ulcer healing and mucosal expression of cyclooxygenase-1 and -2

BACKGROUND/AIMS: Ulcer healing involves expression of various growth factors such as epidermal growth factor (EGF), hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF) at the ulcer margin, but the influence of EGF, HGF and bFGF applied locally with or without neutralizing anti-EGF, HGF and bFGF antibodies or cyclooxygenase (COX)-1 and COX-2 inhibitors on ulcer healing and the expression of COX-1 and COX-2 during ulcer healing have only been studied a little. METHODS: Rats with gastric ulcers induced by serosal application of acetic acid (ulcer area 28 mm2 received a submucosal injection of either (1) vehicle (saline), (2) EGF, (3) HGF, and (4) bFGF with or without antibodies against EGF, HGF and bFGF or indomethacin (2 mg/kg/day i.p.), a nonspecific inhibitor of COX, or NS-398 (10 mg/kg/day i.g.) and Vioxx (5 mg/kg/day i.g.), both highly specific COX-2 inhibitors. A separate group of animals with chronic gastric fistulas was also used to assess gastric secretion during ulcer healing with and without growth factors. Each growth factor and specific antibody against EGF, HGF and bFGF (100 ng/100 microl each) were injected just around the ulcer immediately after ulcer induction and this local injection was repeated on day 2 following anesthesia and laparotomy. On days 13 and 21, the ulcer area was determined by planimetry, gastric blood flow (GBF) at the ulcer margin was examined by the H2-gas clearance technique, and mucosal generation of PGE2 and the gene expression of COX-1 and COX-2 in the non-ulcerated and ulcerated gastric mucosa were assessed. Gastric ulcers healed progressively within 21 days after induction and this effect was accompanied by a significant increase in GBF at the ulcer margin and in the expression of COX-2 in the ulcer area. Local treatment with EGF, HGF and bFGF produced a significant decrease in gastric acid secretion and significantly accelerated the rate of ulcer healing and raised GBF at the ulcer margin causing further significant upregulation of COX-2 but not COX-1 expression in the ulcerated mucosa. The acceleration of ulcer healing and hyperemia at the ulcer margin exhibited by locally applied EGF, HGF and bFGF were similar to those obtained with systemic administration of these growth factors. HGF applied submucosally, upregulated COX-2 expression and this was significantly attenuated by concurrent treatment with antibody against this peptide. Anti-EGF and anti-bFGF antibodies completely abolished the acceleration of the ulcer healing and hyperemia at the ulcer margin induced by these growth factors. Indomethacin and both COX-2 inhibitors significantly prolonged ulcer healing, while suppressing the generation of PGE2 in non-ulcerated and ulcerated gastric mucosa and GBF at the ulcer margin. The acceleration of ulcer healing by EGF, HGF and bFGF and the accompanying rise in GBF at the ulcer margin were significantly attenuated by the concurrent treatment with indomethacin or NS-398 and Vioxx. CONCLUSIONS: (1) Growth factors accelerate ulcer healing due to enhancement in the microcirculation around the ulcer and these effects are specific because they can be abolished by neutralization with antibodies; (2) COX-2-derived prostaglandins and suppression of gastric secretion may play an important role in the acceleration of ulcer healing by various growth factors, and (3) the local effects of EGF, HGF and bFGF on ulcer healing can be reproduced by their systemic application indicating the high efficacy of growth factors to accelerate this healing.     

Transforming Growth Factor Alpha and Epidermal Growth Factor in Protection and Healing of Gastric Mucosal Injury

Transforming growth factor alpha (TGF) and epidermal growth factor (EGF) present in the gastric mucosa are polypeptides with similar biologic activity. This study compares the activity of TGF and EGF in the protection against injury by 100% ethanol and stress and in healing of acute gastric ulcerations. TGF and EGF (12.5-100 μg/kg-h) infused subcutaneously 30 min before and during ethanol or stress decreased mucosal lesions dose-dependently. The ID₅₀ for ethanol- and stress-induced lesions after TGF were 40 and 70 μg/kg-h and after EGF 60 and 100 ug/kg-h. TGF and EGF infused subcutaneously into intact rats inhibited gastric acid secretion but did not affect the gastric blood flow or mucosal generation of prostaglandin E₂ (PGE₂). Both TGF and EGF also significantly enhanced the healing of stress-induced lesions and the restoration of DNA synthesis. Ethanol and stress reduced blood flow in the oxyntic mucosa by 68% and 51%, respectively, and this effect was partially reversed by EGF and TGF. Pretreatment with indomethacin (5 mg/kg intraperitoneally), which reduced mucosal generation of PGE₂ by 85%, decreased in part the protection by TGF and EGF against ethanol-induced damage and virtually abolished the protective action of these peptides against stress-induced injury. We conclude therefore that 1) TGF and EGF show similar and comparable gastroprotective activity against ethanol- and stress-induced damage; 2) the protection by TGF and EGF is accompanied by an increase in gastric blood flow which appears to be an essential factor in gastroprotection; 3) mucosal PG is necessary for manifestation of the protective activity of TGF and EGF against acute gastric damage; and 4) TGF and EGF enhance the healing of gastric lesions, possibly via stimulation of DNA synthesis and cell proliferation.     

The effect of PPIs Alone,PPIs plus cytoprotective agent,and H2RA plus cytoprotective agent on ulcer healing after endoscopic submucosal dissection: A prospective randomized controlled trial

Background and Study AimsEndoscopic submucosal dissection (ESD) is the most effective treatment for early gastric cancer or gastric adenoma. However, ESD results in iatrogenic ulcers and postoperative bleeding from ulcers. This study aimed to evaluate the effect of using a proton pump inhibitor (PPI) alone, a PPI + rebamipide combination therapy, and an H2 receptor antagonist (H2RA) + rebamipide combination therapy on ulcer healing after ESD.Patients and MethodsA total of 204 patients who underwent ESD from April 2014 to July 2017 at Dong-A University Hospital were randomly assigned to the following groups: PPI-alone group, PPI + rebamipide combination therapy group, and H2RA + rebamipide combination therapy group. However, only 156 patients were studied since we excluded those who were lost to follow-up or had diseases other than early gastric cancer or gastric adenoma. Twenty-eight days after ESD, we evaluated the ulcer residual ratio, S stage rates, ulcer bleeding ratio, and gastric pH.ResultsThis study included 156 patients (PPI-alone group: 52 patients; PPI + rebamipide group: 52 patients; H2RA + rebamipide group: 52 patients). The ulcer residual ratios were 24.3 ± 14.2%, 17.0 ± 12.1%, and 21.0 ± 13.8% in the PPI alone, PPI + rebamipide, and H2RA + rebamipide groups, respectively (P = 0.048).ConclusionsPPI + rebamipide was more effective in reducing the ulcer residual ratio after ESD. There was no statistical difference in ulcer stage and delayed bleeding after ESD among the groups. These findings showed that PPI + rebamipide had limited benefits after ESD.     

Cyclo-oxygenase-2 inhibitors suppress epithelial cell kinetics and delay gastric wound healing in rats

BACKGROUND AND AIMS: The present study examined the effects of NS-398, a specific cyclo-oxygenase-2 inhibitor, on gastric mucosal cell kinetics and gastric wound healing following acid-induced injury. METHODS: Male Sprague-Dawley rats were fasted for 24 h and then 0.6 mol/L hydrochloric acid (HCl; 1 mL) was administered into the stomach; NS-398 or indomethacin was administered to the animals 10 min after the acid. Levels of constitutive cyclo-oxygenase (COX-1) and mitogen-inducible cyclo-oxygenase (COX-2) in the gastric mucosa were analysed using western blotting and immunohistochemical staining. The grade of the lesion was assessed using planimetry and histological examination, including immunohistochemistry for proliferating cell nuclear antigen (PCNA). RESULTS: Although there was strong expression of COX-1, there was minimal expression of COX-2 in the gastric mucosa. Expression of COX-2 was enhanced mainly in surface epithelial cells and neck cells following HCl administration. Gastric mucosal ulcers and erosions healed within 48 h, during which time the proliferative zone expanded in the control animals. Indomethacin and NS-398 suppressed the expansion of the proliferative zone and delayed the healing of the gastric injury. CONCLUSION: The present study demonstrated that cyclo-oxygenase-2 inhibitors delay gastric wound healing by suppressing expansion of the mucosal proliferative zone. These results provide evidence that cyclo-oxygenase-2 has an important role in gastric mucosal regeneration.