Antacid provides better restoration of glandular structures within the gastric ulcer scar than omeprazole

Effect of Hydrotalcite on Indometacin-Induced Gastric Injury in Rats

Background and Aims

Hydrotalcite plays an important role in the therapy of gastric ulcer induced by nonsteroidal anti-inflammatory drugs (NSAIDs), but little is known about the mechanism. We designed two experiments to study the preventive and curative effects of hydrotalcite on NSAIDs-related gastric injury in rats and to investigate the relationship between the protective and curative mechanism of hydrotalcite and the secretion of epidermal growth factor (EGF)/prostaglandin E2 (PGE2).

Methods

Two experiments were separately designed to evaluate the preventive and curative effects of hydrotalcite. A total of 25 male rats and 25 female rats were randomly divided into five groups (vehicle group, model group, omeprazole group, hydrotalcite group, and ranitidine group) in each experiment. Rats were treated with indomethacin by gavage to build the model of acute gastric mucosal injury. The concentrations of EGF and PGE2 in blood specimens and mucosal injury indexes by gross inspection were measured and an immunohistochemical technique was also employed to test the levels of EGF, cyclooxygenase-1 (COX-1), and cyclooxygenase-2 (COX-2) in gastric mucosa.

Results

Comparing with model group in both preventive and curative experiments, hydrotalcite decreased the gastric injury in the mucosa of stomach significantly (7±4.5 vs. 16±11.25, 1.5±2 vs. 2.5±6; P<0.01, P<0.05). The levels of EGF and PGE2 in blood serum were markedly higher in hydrotalcite group than that in model group and ranitidine group in preventive experiment (574.39±34.28 vs. 486.22±41.73, 488.07±24.44; P<0.01, P<0.01). The expression levels of COX-2 in gastric mucosa were also higher in hydrotalcite group than that in model group in both preventive and therapeutic experiments (12±4 vs. 9±6, 14±7 vs. 9±4; P<0.01, P<0.05).

Conclusions

Hydrotalcite promotes gastric protection and healing via several mechanisms, including increased levels of PGE2 in blood serum, activation of EGF, and antagonising the inhibition of cyclooxygenase (COX) caused by NSAIDs.

Layered double hydroxides as drug carriers and for controlled release of non-steroidal antiinflammatory drugs (NSAIDs): a review

Non-steroidal anti-inflammatory drugs constitute one of the groups most widely currently used, but show several problems for administration due to low solubility and delivery control. For this reason, several matrices have been tested to support them in order to overcome these drawbacks. Among them, layered double hydroxides have been used in recent years. The aim of this review is to update the current knowledge and findings on this hybrid system, namely, layered double hydroxides intercalated with different NSAIDs. The basic nature of the matrix introduces an additional advantage, i.e., to decrease ulceration damages. We have focused our review mostly on the preparation procedures, as these control, define and determine the performance of the systems in vitro and also in living organisms.

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.

Inhibitors of acid secretion can benefit gastric wound repair independent of luminal pH effects on the site of damage

BACKGROUND AND AIMS

The authors' goal was to measure pH at the gastric surface (pH₀) to understand how acid secretion affects the repair of microscopic injury to the gastric epithelium.

METHODS

Microscopic gastric damage was induced by laser light, during confocal/two-photon imaging of pH-sensitive dyes (Cl-NERF, BCECF) that were superfused over the mucosal surface of the exposed gastric corpus of anaesthetised mice. The progression of repair was measured in parallel with pH₀. Experimental conditions included varying pH of luminal superfusates, and using omeprazole (60 mg/kg ip) or famotidine (30 mg/kg ip) to inhibit acid secretion.

RESULTS

Similar rates of epithelial repair and resting pH₀ values (∼pH 4) were reported in the presence of luminal pH 3 or pH 5. Epithelial repair was unreliable at luminal pH 2 and pH₀ was lower (2.5±0.2, P <0.05 vs pH 3). Epithelial repair was slower at luminal pH 7 and pH₀ was higher (6.4±0.1, P<0.001). In all conditions, pH₀ increased adjacent to damage. At luminal pH 3 or pH 7, omeprazole reduced maximal damage size and accelerated epithelial repair, although only at pH 3 did omeprazole further increase surface pH above the level caused by imposed damage. At luminal pH 7, famotidine also reduced maximal damage size and accelerated epithelial repair. Neither famotidine nor omeprazole raised plasma gastrin levels during the time course of the experiments.

CONCLUSIONS

Epithelial repair in vivo is affected by luminal pH variation, but the beneficial effects of acutely blocking acid secretion extend beyond simply raising luminal and/or surface pH.

On-demand treatment of acute heartburn with the antacid hydrotalcite compared with famotidine and placebo: randomized double-blind cross-over study

BACKGROUND

Antacids are widely used in the self-treatment of gastroesophageal reflux-induced complaints, but respective studies are lacking.

GOALS

To compare the efficacy and safety of hydrotalcite with the H2 receptor antagonist famotidine and placebo in the on-demand treatment of acute heartburn under daily practice conditions.

STUDY

Five hundred sixty-two individuals in 4 centers were randomized in a double-blind, double-dummy, 3-fold cross-over study to single-dose treatments of 1000 mg hydrotalcite, 10 mg famotidine, or placebo. Heartburn severity and relief was measured with numerical and visual rating scales.

RESULTS

A significantly better heartburn relief score was achieved 60 minutes after administration of hydrotalcite compared with placebo (primary end point, P<0.0001). Better efficacy was also observed 30 minutes and 3 hours after the intake of hydrotalcite in comparison with famotidine or placebo. A significant decrease in heartburn severity compared with placebo occurred within 10 minutes for hydrotalcite and was faster compared with both controls.

CONCLUSIONS

For subjects self-administering antacids for episodic heartburn, antacid hydrotalcite provides symptom relief significantly faster and, within the first 3 hours postdosing, more effective than famotidine or placebo. These results suggest that on-demand treatment of hydrotalcite is an effective and well-tolerated therapy for heartburn.

Preventive effect of hydrotalcite on gastric mucosal injury in rats induced by taurocholate

AIM: To study the preventive effect of hydrotalcite on gastric mucosal injury in rat induced by taurocholate, and to investigate the relationship between the protective mechanism of hydrotalcite and the expression of trefoil factor family 2 (TFF2) mRNA and c-fos protein.

METHODS: Forty five male Wistar rats were randomly divided into hydrotalcite group, ranitidine group and control group. Gastric mucosal injury was induced by introgastric acidified taurocholate. OD value of TFF2 mRNA expression in gastric mucous cells was determined by hybridization and computer image analysis system. OD value of c-fos protein expression in gastric mucous cells was measured by immunohistochemistry and computer image analysis system.

RESULTS: The gross mucosal injury index in hydrotalcite group was significantly lower than that in ranitidine group and control group (8.60 ± 2.20 vs 16.32 ± 4.27, 29.53 ± 5.39; P < 0.05, P < 0.01). The expression level of TFF2 mRNA in hydrotalcite group was markedly higher than that in ranitidine group and control group (0.56 ± 0.09 vs 0.30 ± 0.05, 0.28 ± 0.03, P < 0.05). The OD value of c-fos protein in hydrotalcite group was higher than that in ranitidine group and control group (0.52 ± 0.07 vs 0.31 ± 0.04, 0.32 ± 0.05, P < 0.05).

CONCLUSION: Hydrotalcite can protect gastric mucosal injury in rats induced by taurocholate, which may be related to the increased expression of TFF2 and c-fos protein.

Relative contribution of mucosal injury and Helicobacter pylori in the development of gastroduodenal lesions in patients taking non-steroidal anti-inflammatory drugs

BACKGROUND AND AIMS

A past history of peptic ulceration increases the risk of an ulcer developing during non-steroidal anti-inflammatory drug (NSAID) use. Whether this is due to Helicobacter pylori infection or to reactivation of the original lesion is unclear.

METHODS

We used multivariate regression analyses of three large similar trials to identify factors that placed patients at high risk of ulcer development or relapse. We compared the efficacy of omeprazole 20 mg daily, misoprostol 200 micro g twice daily, and ranitidine 150 mg twice daily in preventing ulcers and erosions at different sites and in patients who were H pylori positive and negative.

RESULTS

Patients with endoscopic lesions (which healed) initially were significantly more likely than those without to develop further erosions or ulcers during treatment (rate ratio 2.12, 1.07-4.17). Risk mounted further with ulcers versus erosions, particularly those that had been slow to heal. There was a highly significant tendency for the relapse lesion to replicate the site and type of the original lesion (mean odds ratios ranging from 3 to 14). Treatment failure was significantly less likely with omeprazole than with placebo, misoprostol, or ranitidine. This advantage was especially evident in H pylori positive patients receiving acid suppression (5.7% v 16.6% for gastric ulcer with omeprazole).

CONCLUSIONS

Relapse of lesions in patients taking NSAIDs was highly site and type specific and not adversely affected by H pylori status. This strongly implies that local mucosal factors predispose to ulcer development in patients taking NSAIDs. Identification of the responsible mucosal changes would aid understanding and could promote better treatment.

Effects of omeprazole and famotidine on fibroblast growth factor-2 during artificial gastric ulcer healing in humans

BACKGROUND AND AIMS

Endoscopic mucosal resection is a widely accepted technique for the treatment of early gastric cancers, while large ulcers induced by the treatment should be treated promptly. This study aimed to compare the effects of omeprazole and famotidine on ulcer healing and fibroblast growth factor-2 levels in gastric ulcers induced by endoscopic mucosal resection.

METHODS

Sixteen patients indicated for endoscopic mucosal resection were enrolled. They were treated by using either omeprazole (n = 8) or famotidine (n = 8) after endoscopic mucosal resection. Endoscopy was performed on days 4, 7 and 28 during each treatment period. Levels of fibroblast growth factor-2 in biopsy specimens were measured by using an enzyme-linked immunosorbent assay at the time of and after endoscopic mucosal resection. Histological variables were also assessed.

RESULTS

Ulcer healing rates under endoscopy were not different between the two treatment groups. In both groups, levels of fibroblast growth factor-2 slightly increased on day 4, but the values were not different at any time point. There were no differences in histological variables on days 4 and 7, but fibromuscular hyperplasia was significantly greater in the omeprazole group than in the famotidine group on day 28 (P < 0.05).

CONCLUSIONS

Omeprazole and famotidine have an equivalent value for the treatment of ulcers induced by endoscopic mucosal resection. While omeprazole had a more potent effect on fibromuscular hyperplasia than did famotidine, such a difference does not seem to be explained by fibroblast growth factor-2.

Effects of NSAIDs on cryoprobe-induced gastric ulcer healing in rats

BACKGROUND

Failure of ulcer healing may be critically important to the development of serious gastrointestinal complications in patients on long-term NSAIDs.

AIM

To determine the effect of indometacin, celecoxib, a cyclooxygenase-2-specific inhibitor, and nabumetone, a pro-drug, on ulcer healing rates in the rat.

METHODS

Gastric ulcers were induced using a cryoprobe. An NSAID or a vehicle control was administered to groups of eight rats for 3 or 6 days (2 mg/kg indometacin, 9 mg/kg celecoxib or 40 mg/kg nabumetone). The ulcer area was measured and epithelial proliferation at the ulcer margins was measured histochemically. The effect of the drugs on intestinal prostaglandin levels was also assessed.

RESULTS

The mean ulcer sizes in the four groups on day 3 were comparable. On day 6, control animals and those receiving nabumetone showed significant ulcer healing (P < 0.02), while the mean ulcer sizes in the indometacin (P < 0.01) and celecoxib (P < 0.02) groups were significantly larger than those in the control group. Higher doses of nabumetone (160 mg/kg), however, impaired healing. Intestinal prostaglandins were reduced (P < 0.01) only in indometacin-treated animals. The epithelial proliferation index was significantly lower among indometacin- (P=0.02) and celecoxib-treated (P=0.03) animals compared to controls at day 3.

CONCLUSIONS

Celecoxib and indometacin both decreased the epithelial proliferative response and delayed healing of cryoprobe-induced gastric ulcers. In contrast, nabumetone impaired ulcer healing only at very high doses.

Antacid talcid activates in gastric mucosa genes encoding for EGF and its receptor. The molecular basis for its ulcer healing action

In previous studies [Gut 35 (1994) 896-904], we demonstrated that antacid talcid (TAL) accelerates gastric ulcer healing and provides better quality of mucosal restoration within the scar than the omeprazole (OME). However, the mechanisms of TAL-induced ulcer healing are not clear. Since growth factors promote cell proliferation, re-epithelization, angiogenesis and ulcer healing, we studied whether TAL and/or OME affect expression of epidermal growth factor (EGF) and its receptors (EGF-R) in both normal and ulcerated gastric mucosae. Rats with or without acetic acid-induced gastric ulcers (n = 64) received i.g. twice daily 1 mL of either: A) placebo (PLA); B) TAL 100 mg; or C) OME 50 mg x kg(-1) for 14 d. Studies of gastric specimens: 1) ulcer size; 2) quantitative histology; 3) expression of EGF mRNAs was determined by RT/PCR; 4) gastric sections were immunostained with antibodies against EGF and its receptors. In non-ulcerated gastric mucosa of placebo or omeprazole treated group, EGF expression was minimal, while EGF-R was localized to few cells in the mucosal proliferative zone. Gastric ulceration triggered overexpression of EGF and its receptor in epithelial cells of the ulcer margin and scar. In ulcerated gastric mucosa TAL treatment significantly enhanced (versus PLA and omeprazole) expression of EGF and EGF-R. OME treatment reduced expression of EGF in ulcerated mucosa by 55 +/- 2% (P < 0.01). It is concluded that: 1) treatment with TAL activates genes for EGF and its receptor in normal and ulcerated gastric mucosae; 2) since EGF promotes growth of epithelial cells and their proliferation and migration, the above actions of TAL provide the mechanism for its ulcer healing action and improved (versus OME) quality of mucosal restoration.

Mechanisms of ulcer healing and effects of nonsteroidal anti-inflammatory drugs

Ulceration of the gastroduodenal mucosa occurs frequently in humans, particularly in patients with a history of peptic ulcer disease. In order for healing to occur, mucosal damage stimulates secretion of growth factors in the adjacent mucosa and ulcer bed. Peptic ulcer healing is accomplished by the filling of the mucosal defect with cells that migrate from the ulcer margin and by connective tissue, including microvessels originating from granulation tissue. Peptic ulcer healing is accelerated both in humans and experimental models by gastric acid inhibition, which enhances cell migration and maturation of the granulation tissue. In experimental models, peptic ulcer healing can also be accelerated by oral administration of basic fibroblast growth factor, which increases angiogenesis in the ulcer bed, or by nitric oxide-releasing compounds, which improve gastric blood flow. Clinical and experimental data indicate that traditional nonsteroidal anti-inflammatory drugs (NSAIDs) delay the healing of peptic ulcers by interfering with the action of growth factors, decreasing epithelial cell proliferation in the ulcer margin, decreasing angiogenesis in the ulcer bed, and slowing maturation of the granulation tissue. In order to reduce the gastroduodenal side-effects of NSAIDs, selective cyclo-oxygenase (COX)-2 inhibitors have been developed, which inhibit the inducible COX-2 isoform in inflammatory tissue but have only limited effect on the constitutive COX-1 isoform in the stomach. It has been reported that the selective COX-2 inhibitor L-745,337 has a reduced liability for gastrointestinal ulceration. In our chronic experimental gastric ulcer model in rats, however, delay of gastric ulcer healing with L-745,337 was comparable to that with ordinary NSAIDs. It has also been reported that nitric oxide-releasing NSAIDs have a low relative risk of gastrointestinal ulceration but, again, in our chronic gastric ulcer model, nitric oxide did not reverse NSAID-induced deleterious effects on ulcer healing. In contrast, the proton pump inhibitor omeprazole has been shown to reverse NSAID-induced deleterious effects on gastric ulcer healing in our model. Comparable results have also been reported in humans. Histologic analysis has shown that omeprazole reverses the effects of NSAIDs on cell proliferation, angiogenesis, and maturation of the granulation tissue. In conclusion, only highly effective gastric acid inhibition reliably reverses NSAID-induced delay of gastric ulcer healing.

Effects of inhibition of prostaglandin endoperoxide synthase-2 in chronic gastro-intestinal ulcer models in rats

1. In the stomach, prostaglandins protect the gastric mucosa against injuries. One rate-limiting step in prostaglandin synthesis is mediated by prostaglandin endoperoxide synthase (PGHS), the target enzyme of non-steroidal anti-inflammatory drugs (NSAIDs). Two isoforms of PGHS exist: a constitutive (PGHS-1) and an inducible (PGHS-2) enzyme. PGHS-1 is the major source of gastric prostaglandins under physiological conditions. Inhibition of prostaglandin synthesis by traditional NSAIDs such as indomethacin and diclofenac which non-selectively inhibit both PGHS-1 and PGHS-2, causes gastric and intestinal ulceration and delays gastric ulcer healing in chronic models. It has been shown that selective PGHS-2 inhibitors such as L-745,337 (5-methanesulphonamide-6-(2,4-difluorothio-phenyl)-1-inda none) are not ulcerogenic and do not inhibit gastro-intestinal prostaglandin synthesis. However, minimal information is available on the long-term effects of PGHS-2 inhibitors on the healing of previously established gastric injuries. We assessed the cellular localization and expression of PGHS-1 and PGHS-2 during gastric ulcer healing and assessed the effects of L-745,337 on previously established cryoulcers in the rat gastric stomach. 2. PGHS-1 and PGHS-2 were located and quantified by immunohistochemistry during experimental gastric ulcer healing. PGHS-2 immunoreactivity was only negligible in the normal gastric wall, but after gastric ulcerations, it was strongly detected in monocytes, macrophages, fibroblasts and endothelial cells below and between the regenerative glands. PGHS-1 immunoreactivity detected in normal gastric mucosa, disappeared after gastric ulceration in the mucosa adjacent to the ulcer crater. However, it reappeared in the regenerative glands from day 5 onwards. Thus, PGHS-1 and PGHS-2 were located at different sites and their maximal expression followed a different time-sequence. 3. We assessed the effects of L-745,337, indomethacin and diclofenac on gastric ulcer healing and histological healing parameters in rats. L-745,337, indomethacin and diclofenac dose-dependently decreased the healing of gastric ulcers. L-745,337, indomethacin and diclofenac decreased epithelial cell proliferation in the ulcer margin and microvessel density in the ulcer bed on day 8 and increased the thickness of the granulation tissue below the ulcer crater and the gap between both edges of the muscularis mucosae on day 15. Indomethacin and diclofenac, but not L-745,337, decreased synthesis of 6-keto-PGF1alpha and PGE2 in tissue fragments from the stomach and terminal ileum and decreased platelet thromboxane B2 synthesis in clotting whole blood. 4. Dose-response curves for the inhibition of chronic gastric ulcer healing by L-745,337 (administered twice daily intragastrically) showed an ID50 value of 1.7 mg (4.3 micromol) kg(-1). Dose-response curves for the inhibition of PGE2 synthesis in inflammatory exudates in the acute carrageenin sponge rat model, showed ID50 values of 1.1 mg (3.1 micromol) kg(-1) and 1.3 (3.3 micromol) mg kg(-1) for indomethacin and L-745,337, respectively. Thus, inhibition of chronic gastric ulcer healing by L-745,337 occurs within a potentially therapeutic dose-range. 5. In summary, PGHS-2 is markedly accumulated after gastric ulceration in monocytes, macrophages, fibroblasts and endothelial cells in regions of maximal repair activity. Selective inhibition of PGHS-2 by L-745,337 delayed gastric ulcer healing though interference with epithelial cell proliferation, angiogenesis and maturation of granulation tissue in a potentially therapeutic dose range. PGHS-2-derived prostaglandins seem to have an important role in gastric ulcer healing.

Aspirin-like drugs cause gastrointestinal injuries by metallic cation chelation

Aspirin-like (nonsteroidal anti-inflammatory) drugs may cause injuries including ulcers to the gastrointestinal tract by chelation of the divalent and/or multivalent metallic cations in the gastrointestinal mucus and mucosa, as suggested by the chemical properties of these drugs and supported by experimental and clinical data.

Healing with basic fibroblast growth factor is associated with reduced indomethacin induced relapse in a human model of gastric ulceration

BACKGROUND

Acid stable basic fibroblast growth factor (bFGF) promotes angiogenesis and healing of gastric ulcers in rats and reduces subsequent non-steroidal anti-inflammatory drug (NSAID) induced relapse.

AIMS

To test in a double blind, placebo controlled, three way crossover study whether bFGF promotes healing and reduces subsequent relapse in a human model of gastric ulceration.

SUBJECTS

Twelve healthy volunteers.

METHODS

Subjects took aspirin 900 mg twice daily (days 1-3) with bFGF 0.1 mg twice daily or cimetidine 400 mg twice daily or placebo (days 1-14) and then indomethacin 50 mg thrice daily (days 15-21). Endoscopy was performed on days 1, 4, 8, 15, and 22 during each treatment period. Eight antral biopsy specimens were taken on day 1 and the number of unhealed biopsy induced mini-ulcers and NSAID induced erosions counted during subsequent endoscopies.

RESULTS

Basic FGF and cimetidine were protective against aspirin and indomethacin induced duodenal (but not gastric) injury compared with placebo. There was significant relapse of biopsy induced mini-ulcers after indomethacin only in the placebo group (0 (0-0) before v 1 (0-4.5) after; p > 0.05). TGP-580 was detected in serum of one volunteer.

CONCLUSIONS

Healing with bFGF (and cimetidine) was associated with reduced NSAID induced ulcer relapse in this model of gastric ulceration.

Restitution at the cellular level: regulation of the migrating phenotype

Intestinal epithelial cells migrating across a mucosal defect are generally described as dedifferentiated, a term that suggests a loss of regulatory biology. Since cell biology may be more readily studied in established cell lines than in vivo, a model is developed using the human Caco-2 intestinal epithelial cell migrating across matrix proteins. This resembles in vivo models of mucosal healing in its sheet migration and loss of the brush border enzymes, which are conventional markers for intestinal epithelial differentiation. Immunohistochemical studies of migrating Caco-2 cells suggest, however, that the rearrangements of cytoskeletal, cell-cell and cell-matrix proteins during migration are not random but seem adapted to the migratory state. Indeed, Caco-2 migration may be substantially regulated by a variety of physiologic and pharmacologic stimuli and differentiation, measured by the specific activity of the intestinal epithelial brush border enzymes alkaline phosphatase and dipeptidyl dipeptidase, may be independently pharmacologically programmed during the stimulation or inhibition of cell motility.