Adaptation of esophageal mucosa to acid- and pepsin-induced damage: role of nitric oxide and epidermal growth factor

Topical Alginate Protection against Pepsin-Mediated Esophageal Damage: E-Cadherin Proteolysis and Matrix Metalloproteinase Induction

Epithelial barrier dysfunction is a hallmark of gastroesophageal reflux disease (GERD) related to symptom origination, inflammatory remodeling and carcinogenesis. Alginate-based antireflux medications were previously shown to topically protect against peptic barrier disruption, yet the molecular mechanisms of injury and protection were unclear. Herein, Barrett's esophageal (BAR-T) cells were pretreated with buffered saline (HBSS; control), dilute alginate medications (Gaviscon Advance or Gaviscon Double Action, Reckitt Benckiser), a viscosity-matched placebo, or ADAM10 and matrix metalloproteinase (MMP) inhibitors before exposure to HBSS pH7.4 or pH4 ± 1 mg/mL pepsin for 10-60 min. Cell viability was assessed by ATP assay; mediators of epithelial integrity, E-cadherin, ADAM10, and MMPs were examined by Western blot and qPCR. Alginate rescued peptic reduction of cell viability (p < 0.0001). Pepsin-pH4 yielded E-cadherin fragments indicative of regulated intramembrane proteolysis (RIP) which was not rescued by inhibitors of known E-cadherin sheddases. Transcriptional targets of E-cadherin RIP fragments were elevated at 24 h (MMP-1,2,9,14; p < 0.01). Alginate rescued E-cadherin cleavage, ADAM10 maturation, and MMP induction (p < 0.01). Results support RIP as a novel mechanism of peptic injury during GERD. Alginate residue after wash-out to mimic physiologic esophageal clearance conferred lasting protection against pepsin-induced molecular mechanisms that may exacerbate GERD severity and promote carcinogenesis in the context of weakly acidic reflux.

Gaseous mediators nitric oxide and hydrogen sulfide in the mechanism of gastrointestinal integrity, protection and ulcer healing

Nitric oxide (NO) and hydrogen sulfide (H2S) are known as biological messengers; they play an important role in human organism and contribute to many physiological and pathophysiological processes. NO is produced from l-arginine by constitutive NO synthase (NOS) and inducible NOS enzymatic pathways. This gaseous mediator inhibits platelet aggregation, leukocyte adhesion and contributes to the vessel homeostasis. NO is known as a vasodilatory molecule involved in control of the gastric blood flow (GBF) and the maintenance of gastric mucosal barrier integrity in either healthy gastric mucosa or that damaged by strong irritants. Biosynthesis of H2S in mammals depends upon two enzymes cystathionine-β-synthase and cystathionine γ-lyase. This gaseous mediator, similarly to NO and carbon monoxide, is involved in neuromodulation, vascular contractility and anti-inflammatory activities. For decades, H2S has been known to inhibit cytochrome c oxidase and reduce cell energy production. Nowadays it is generally considered to act through vascular smooth muscle ATP-dependent K+ channels, interacting with intracellular transcription factors and promote sulfhydration of protein cysteine moieties within the cell, but the mechanism of potential gastroprotective and ulcer healing properties of H2S has not been fully explained. The aim of this review is to compare current results of the studies concerning the role of H2S and NO in gastric mucosa protection and outline areas that may pose new opportunities for further development of novel therapeutic targets.

From reflux esophagitis to Barrett’s esophagus and esophageal adenocarcinoma

The occurrence of gastroesophageal reflux disease is common in the human population. Almost all cases of esophageal adenocarcinoma are derived from Barrett’s esophagus, which is a complication of esophageal adenocarcinoma precancerous lesions. Chronic exposure of the esophagus to gastroduodenal intestinal fluid is an important determinant factor in the development of Barrett’s esophagus. The replacement of normal squamous epithelium with specific columnar epithelium in the lower esophagus induced by the chronic exposure to gastroduodenal fluid could lead to intestinal metaplasia, which is closely associated with the development of esophageal adenocarcinoma. However, the exact mechanism of injury is not completely understood. Various animal models of the developmental mechanisms of disease, and theoretical and clinical effects of drug treatment have been widely used in research. Recently, animal models employed in studies on gastroesophageal reflux injury have allowed significant progress. The advantage of using animal models lies in the ability to accurately control the experimental conditions for better evaluation of results. In this article, various modeling methods are reviewed, with discussion of the major findings on the developmental mechanism of Barrett’s esophagus, which should help to develop better prevention and treatment strategies for Barrett’s esophagus.

Animal model of acid-reflux esophagitis: pathogenic roles of acid/pepsin, prostaglandins, and amino acids

Esophagitis was induced in rats within 3 h by ligating both the pylorus and transitional region between the forestomach and glandular portion under ether anesthesia. This esophageal injury was prevented by the administration of acid suppressants and antipepsin drug and aggravated by exogenous pepsin. Damage was also aggravated by pretreatment with indomethacin and the selective COX-1 but not COX-2 inhibitor, whereas PGE₂ showed a biphasic effect depending on the dose; a protection at low doses, and an aggravation at high doses, with both being mediated by EP1 receptors. Various amino acids also affected this esophagitis in different ways; L-alanine and L-glutamine had a deleterious effect, while L-arginine and glycine were highly protective, both due to yet unidentified mechanisms. It is assumed that acid/pepsin plays a major pathogenic role in this model of esophagitis; PGs derived from COX-1 are involved in mucosal defense of the esophagus; and some amino acids are protective against esophagitis. These findings also suggest a novel therapeutic approach in the treatment of esophagitis, in addition to acid suppressant therapy. The model introduced may be useful to test the protective effects of drugs on esophagitis and investigate the mucosal defense mechanism in the esophagus.

Orally administered L-arginine and glycine are highly effective against acid reflux esophagitis in rats

Background

Reflux esophagitis is caused mainly by excessive exposure of the mucosa to gastric contents. In the present study, we examined the effect of several amino acids on acid reflux esophagitis in rats.

Material/Methods

After 18 h of fasting, acid reflux esophagitis was induced by ligating both the pylorus and the transitional region between the forestomach and the corpus under ether anesthesia, and the animals were killed 4 h later. The severity of esophagitis was reduced by the oral administration of omeprazole, a proton pump inhibitor, or pepstatin, a specific pepsin inhibitor.

Results

The development of esophageal lesions was dose-dependently prevented by L-arginine and glycine, given intragastrically (i.g.) after the ligation, with complete inhibition obtained at 250 mg/kg and 750 mg/kg, respectively, and these effects were not influenced by the prior s.c. administration of indomethacin or L-NAME. By contrast, both L-alanine and L-glutamine given i.g. after the ligation aggravated these lesions in a dose-dependent manner. These amino acids had no effect on acid secretion but increased the pH of the gastric contents to 1.8~2.3 due to their buffering action.

Conclusions

The results confirmed an essential role for acid and pepsin in the pathogenesis of acid reflux esophagitis in the rat model and further suggested that various amino acids affect the severity of esophagitis in different ways, due to yet unidentified mechanisms; L-alanine and L-glutamine exert a deleterious effect on the esophagitis, while L-arginine and glycine are highly protective, independent of endogenous prostaglandins and nitric oxide.

Melatonin protects against experimental reflux esophagitis

Reflux esophagitis (RE), a major gastrointestinal disorder results from excess exposure of the esophageal mucosa to acidic gastric juice or bile-containing duodenal contents refluxed via an incompetent lower esophageal sphincter. Recent studies implicated oxygen derived free radicals in RE induced esophageal mucosal damage resulting in mucosal inflammation. Thus, control over free radical generation and modulation of inflammatory responses might offer better therapeutic effects to counteract the severity of RE. In this context we investigated the effect of melatonin against experimental RE in rats. Melatonin pretreatment significantly reduced the haemorrhagic lesions and decreased esophageal lipid peroxidation aggravated by RE. Moreover, the depleted levels of superoxide dismutase and glutathione observed in RE were replenished by melatonin signifying its free radical scavenging properties and antioxidant effects resulting in the improvement of esophageal defense mechanism. Further melatonin repressed the upregulated levels of expression of proinflammatory cytokines like, TNF-alpha, IL-1beta and IL-6 in RE. However, increased levels of the anti-inflammatory cytokine IL-10 remained unaltered after melatonin administration signifying its immunomodulatory effect through suppression of Th1-mediated immune responses. The involvement of receptor dependent actions of melatonin against RE were also investigated with MT2 receptor antagonist, luzindole (LUZ). LUZ failed to antagonize melatonin's protective effects against RE indicating that melatonin mediated these beneficial effects in a receptor-independent fashion. Thus, esophageal mucosal protection elicited by melatonin against experimental RE is not only dependent on its free radical scavenging activity but also mediated in part through its effect on the associated inflammatory events in a receptor-independent manner.

ERBBs in the gastrointestinal tract: recent progress and new perspectives

The gastrointestinal epithelium does much more than provide a physical barrier between the intestinal lumen and our internal milieu. It is actively engaged in absorption and secretion of salt and water via ion transporters, exchangers and selective ion channels. It is also a continuously self-renewing epithelium that undergoes ordered growth and differentiation along its vertical axis. From this dual perspective, we will consider the actions of the ERBB family of ligands and receptors in the maintenance of gastrointestinal homeostasis and discuss instances when the actions of this family go awry such as in cancer and Ménétrier's disease.

Protective effects of cholinergic anti-inflammatory pathway against acute esophagitis in rats

AIM: To investigate the effects of cholinergic anti-inflammatory pathway (CAP) on levels of cytokines, choline acetyltransferase (ChAT) and nitric oxide synthetase (NOS) activities and on the degree of acute esophagitis in rats, and to determine whether CAP has protective effects against experimental esophagitis in rats.

METHODS: Acute esophagitis was induced by perfusion of 0.1 mol/L hydrochloric acid with pepsin in the lower part of the esophagus. Forty SD rats were randomly assigned to five groups. Group 1 served as a normal saline-treated control (NS group), while in group 2 the distal esophagus was exposed to acidified pepsin for 2 h (AP group). In the other three groups, animals were subjected to sham surgery (SHAM group) or bilateral cervical vagotomy alone (VTM group) or with electrical stimulation before and after acid perfusion (VNS group). The levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10) and activities of ChAT and NOS in the esophageal tissues were determined. Esophageal injury was assessed by macroscopic and microscopic examination.

RESULTS: The levels of TNF-α, IL-6, IL-10 and activities of ChAT and NOS in the esophageal tissues increased after acid perfusion. Compared to the SHAM group, vagus nerve electrical stimulation inhibited the release of TNF-α (135.6 ± 11.6 vs 200.0 ± 20.5, P < 0.05), IL-6 (166.9 ± 44.3 vs 305.6 ± 16.5, P < 0.05) and the degree of esophagitis, while the anti-inflammatory cytokine IL-10 was not affected. Conversely, vagotomy resulted in an elevated severity of esophagitis, associated with significant increase of TNF-α (283.8 ± 33.6 vs 200.0 ± 20.5, P < 0.05) and IL-6 (515.1 ± 77.1 vs 305.6 ± 16.5, P < 0.01) levels and decrease of NOS activity. The esophagitis score was significantly higher in acid treatment group than that in NS group (P < 0.01). The macroscopic and microscopic scores increased in VTM group compared with that in SHAM group (P < 0.01 and 0.05). The esophagitis score was decreased markedly in VNS group compared with that in VTM group (P < 0.01).

CONCLUSION: The results of this study provide evidence for the involvement of the cholinergic anti-inflammatory pathway in modulating inflammation and injury during experimental esophagitis.

Mechanisms of heartburn

Heartburn is a typical symptom of GERD. The spectrum of diseases associated with GERD includes reflux esophagitis, Barrett's esophagus and nonerosive reflux disease (NERD). Although acid reflux is the classic cause of heartburn in patients with erosive esophagitis, the relationship between acid and heartburn is far from clear, especially in patients with NERD. Strong evidence exists that weakly acidic reflux and/or non-acid-related events have a significant role in the generation of heartburn. In addition to the role of nonacidic refluxate components, activation of mechanoreceptors and chemoreceptors, and a possible role for central and peripheral sensitization, has been described. Although patients with erosive esophagitis respond well to acid-suppressive therapy, the same does not hold true for those with NERD. NERD represents a major clinical problem, and its management remains a challenge. Discussion of NERD focuses on the mechanisms that cause chest pain in this subgroup of patients. Improved understanding of the pathogenesis underlying heartburn in patients with GERD, in particular those with NERD, will shape our understanding of this condition. Such understanding will serve as a platform for further research and allow additional therapies to be developed for this increasingly encountered clinical condition.

Protective effects of Helicobacter pylori against gastroesophageal reflux disease may be due to a neuroimmunological anti-inflammatory mechanism

There is some evidence that Helicobacter pylori infection has a protective effect against gastroesophageal reflux disease (GORD) and its complications such as Barrett's oesophagus and oesophageal adenocarcinoma. In this paper, we propose that a neuroimmunological mechanism is responsible for the protective effect of H. pylori on GORD. H. pylori infection of the gastric mucosa induces a T helper1-like immune response and production of pro-inflammatory cytokines. These cytokines can inhibit local sympathetic tone, whereas they increase systemic sympathetic tone. Increased sympathetic tone can induce an anti-inflammatory milieu, which in turn can inhibit inflammation in the oesophagus and lower oesophageal sphincter (LOS). Furthermore, H. pylori infection may stimulate the cholinergic anti-inflammatory pathway. It has been suggested that reflux-induced oesophageal inflammation plays an important role in the pathogenesis of reflux oesophagitis. Reduction of oesophageal inflammation by increased systemic sympathetic tone and vagal activity may lead to a decrease in reflux-induced oesophageal injury and LOS dysfunction in GORD.

Review article: the role of bile and pepsin in the pathophysiology and treatment of gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease is a multifaceted and multifactorial disorder which results from the reflux of gastric contents into the oesophagus. Animal studies suggest that synergism between acid and pepsin and conjugated bile acids have the greatest damaging potential for oesophageal mucosa, although unconjugated bile acids may be caustic at more neutral pH. Human studies are compatible with a synergistic action between acid and duodenogastric reflux in inducing lesions. During prolonged monitoring studies, typical gastro-oesophageal reflux symptoms are more related to acid reflux events than to non-acid reflux events. However, symptoms that persist during acid suppressive therapy are often related to non-acid reflux events. The therapeutic options for the non-acid component of the refluxate, including acid suppression, prokinetics, baclofen, surgery and mucosal protective agents like alginates, are discussed.

Expression of transforming growth factor alpha and epidermal growth factor receptor in Barrett's esophagus and esophageal adenocarcinoma

AIM: To investigate the expression of transform-ing growth factor alpha (TGF-α) and epidermal growth factor receptor (EGFR) in Barrett's esophagus and esophageal adenocarcinoma.

METHODS: Immunohistochemistry (SABC assay) was used to detect the expression of TGF-α and EGFR protein in patients with reflux esophagitis (n = 13), Barrett's esophagus (n = 17), esophageal adenocarcinoma (n = 11) and normal esophageal mucosa (n = 30).

RESULTS: In the development of reflux esophagitis, Barrett's esophagus and esophageal adenocarcinoma, the expression of TGF-α and EGFR protein increased gradually and closely correlated with each other (r = 0.951, P < 0.01). TGF-α protein was mainly expressed in the cytoplasm. EGFR was expressed in the cellular membrane in the normal esophageal mucosa and reflux esophagitis, but strongly positively expression was also observed in the cytoplasm and nucleus of cells in Barrett's esophagus with dysplasia and esophageal adenocarcinoma.

CONCLUSION: TGF-α and EGFR expression increase and may play synergic roles in the development of Barrett's esophagus and esophageal adenocarcinoma.

Essential role of pepsin in pathogenesis of acid reflux esophagitis in rats

Pepsin, a protease activated by gastric acid, is a component of the refluxate, yet the role of pepsin in the pathogenesis of reflux esophagitis has not been well studied. In the present study, we examined the effect of pepstatin, a specific inhibitor of pepsin, on acid reflux esophagitis. Acid reflux esophagitis was induced in rats by ligating both the pylorus and the forestomach for 3 or 4 hr. Pepstatin, ecabet Na (the anti-ulcer drug), and L-glutamine were administered intragastrically after the ligation. Pepstatin or ecabet Na, given intragastrically, significantly prevented esophageal lesions, even though they did not affect basal acid secretion in pylorus-ligated rats. Pepstatin significantly inhibited pepsin activity in vivo and in vitro, while ecabet Na inhibited this activity in vitro. By contrast, L-glutamine given intragastrically aggravated the lesions in a dose-dependent manner, but even in the presence of L-glutamine the development of esophageal lesions was totally prevented by coadministration of pepstatin or ecabet Na. L-Glutamine increased the pH of gastric contents to approximately 2.0, the optimal pH for the proteolytic activity of pepsin in vitro. In addition, intragastric administration of exogenous pepsin worsened the severity of esophageal damage. These results suggest that pepstatin is highly effective against acid reflux esophagitis, without influencing acid secretion, while L-glutamine aggravated these lesions by increasing the pepsin activity by shifting the intraluminal pH to the optimal pH range for proteolytic action. It is assumed that pepsin plays a major pathogenic role in the development of acid reflux esophagitis.

Minimal changes in reflux esophagitis: red ones and white ones

Minimal change esophagitis is commonly accepted as part of the spectrum of reflux esophagitis in Japan as well as in many reflux esophagitis classification systems. However, the Los Angeles system excludes minimal changes as a sign of reflux esophagitis because of low interobserver agreement. The high prevalence of minimal change esophagitis suggests that many endoscopists can recognize such findings in their patients' esophagi. However, we do not have a clear definition of minimal changes, which requires proven interobserver agreement, histological evidence, and response data to therapeutic intervention. Furthermore, erythematous changes (red ones) and acanthotic changes (white ones) are not distinguished in the definition of minimal change used in Japan. It is time to clarify such issues.

Acid challenge to the human esophageal mucosa: effects on epithelial architecture in health and disease

The histological changes that occur in the squamous epithelium in response to acute acid challenge was examined in healthy controls and proton pump inhibitor-treated gastroesophageal reflux disease (GERD) patients and related to the state of untreated erosive GERD in a saline-controlled, randomized perfusion study. In the basal state a stepwise significant increase in the thickness of the basal cell layer, papillary length, and dilatation of intercellular spaces (DIS) was seen when the three groups were compared. Acid perfusion induced a slight increase in the height of the basal cell layer mainly in healthy volunteers; this layer appears to be reactive to acute acid challenge as well as to acid suppressive therapy. DIS increases promptly in response to acute acid exposure in the healthy epithelium but no changes were seen in the lengths of the papillae or regarding DIS in the GERD patients. A protective effect of luminal nitric oxide on DIS development is suggested.

[Esophageal complications of non steroidal antiinflammatory drugs]

The effect of non steroidal anti-inflammatory drugs (NSAIDs) on esophageal mucosa is not well known. NSAIDs do not provoke gastro-esophageal reflux disease in healthy subjects but can worsen a preexistant non symptomatic reflux. Mechanism of action is not determined; NSAIDs do not modify the motility of lower esophagus sphincter or of esophageal body. A significant increase of symptoms of GERD (hearthburn and acid regurgitation) is observed in patients treated with NSAIDs. Relative risk of GERD symptoms with NSAIDs is about 2. Erosive esophagitis is common in elderly patients taking NSAIDs but it is not proven that an increased risk of esophagitis exists with NSAID therapy. Case-control studies favored an association between NSAIDs consumption and benign esophageal stricture. NSAIDs can provoke a pill-induced esophagitis, specially if the drugs are absorbed without water and in case of preexistant acid reflux.

Acid challenge to the esophageal mucosa: effects on local nitric oxide formation and its relation to epithelial functions

To evaluate the effect of esophageal acid exposure on epithelial function, transmucosal potential, histopathological markers of acute tissue damage, and local nitric oxide production were examined in healthy volunteers treated with proton pump inhibitors (group I), patients with treated reflux disease (group II), and patients with untreated erosive reflux disease (group III). The participants were randomized to esophageal perfusion with either saline or HCl. Denominators of acute acid exposure were balloon cells in superficial layers and superficial densification. The nitric oxide concentrations in groups I to III increased from < 1, 10.0+/-10.0, and 20.6+/-19.9 ppb, respectively, to 300+/-80, 1360+/-1080, and 920+/-700 ppb after HCl infusion (P < 0.001). Inducible nitric oxide synthase was consistently expressed in the epithelium. Blood flow was lower among reflux patients but did not correlate with acid exposure or nitric oxide. Nitric oxide is formed following acid perfusion and predominantly in gastroesophageal reflux disease.

Changing role of in vivo models in columnar-lined lower esophagus

Columnar-lined lower esophagus (CLE) or Barrett's esophagus (BE) is caused by chronic reflux of the gastrointestinal tract and can progress to invasive adenocarcinoma. However, the pathophysiology, cell of origin, and management of this condition is incompletely understood. This review evaluates the role of in vivo models in resolving these debates. A search was performed on the Ovid and Pub Medline for 1964-2001 and Cochrane Collaboration. The keywords used were adenocarcinoma, animal model, Barrett's esophagus, columnar-lined esophagus, esophageal neoplasms, and esophageal carcinogenesis. All relevant papers were scrutinized and an attempt at tabulation was made. In vivo models have been used at several stages of debate on the pathophysiology of BE. They provide conclusive evidence for its acquired nature secondary to duodenogastroesophageal reflux. The cell of origin of experimental BE may arise from adjacent columnar epithelium, basal layer multipotent cells, or esophageal glands. Experimental work on BE is lacking in assessing therapeutic modalities.

Long-term lansoprazole control of gastric acid and pepsin secretion in ZE and non-ZE hypersecretors: a prospective 10-year study

BACKGROUND

The majority of patients with Zollinger-Ellison syndrome require lifelong treatment with proton pump inhibitors.

AIMS

To determine the efficacy of lansoprazole control of acid and pepsin secretion over the long term in Zollinger-Ellison syndrome and non-Zollinger-Ellison syndrome hypersecretors.

METHODS

Sixty-three hypersecretors (basal acid output > 15 mmol/h), 46 Zollinger-Ellison syndrome and 17 non-Zollinger-Ellison syndrome, with a total history of 15.4 and 19.2 years, respectively, were entered into a long-term prospective study using lansoprazole. Sixty-one were studied every 3 months for 1 year and then every 3-6 months up to 10 years during lansoprazole treatment with endoscopy, serum gastrin and gastric analysis, measuring both basal and stimulated pH and acid and pepsin secretion. Doses were individually optimized and adjusted to keep the basal acid output at < 5 mmol/h in intact patients and < 1 mmol/h in antrectomized Zollinger-Ellison syndrome patients.

RESULTS

The dose of lansoprazole could not be predicted a priori from pre-treatment acid or pepsin output, serum gastrin, prior omeprazole dose or diagnosis or prior complications. The median dose was approximately 80 mg/day, with a wide range from 15 mg every other day to 360 mg/day, and generally stabilized by 12 months. However, as doses were adjusted over time for indications, almost half the patients required higher doses. With adjustments, the basal acid output was maintained in the target range in > 90% of intact patients and in 80% of antrectomized patients. Gastric juice pH increased from approximately 1.2 before therapy to > 3.4 during therapy. Serum gastrin in Zollinger-Ellison syndrome patients, after excluding five outliers, did not change over the course of therapy, but doubled in non-Zollinger-Ellison syndrome patients. There were no adverse events due to lansoprazole, and routine laboratory studies remained normal.

CONCLUSIONS

The dose of lansoprazole for hypersecretors cannot be predicted, and thus needs to be optimized empirically on an individual basis. With continued periodic adjustments, almost half the patients required increased doses, while safe dose reduction was possible in only one-quarter. When individually optimized, lansoprazole proved to be safe and effective in the control of secretion for the treatment of both Zollinger-Ellison syndrome and non-Zollinger-Ellison syndrome hypersecretors for up to 10 years.

Effects of caffeic acid phenethyl ester and epidermal growth factor on the development of caustic esophageal stricture in rats

BACKGROUND/PURPOSE

An experimental study was performed to modify the healing response in caustic esophageal burns to prevent stricture development. Two different agents with different modes of actions, caffeic acid phenethyl ester (CAPE) and epidermal growth factor (EGF), were studied. CAPE has antiinflammatory, immunomodulatory, antioxidant, and antimitotic properties. EGF has known properties in supporting wound healing and in protecting esophagus from injuries.

METHODS

The model described by Gehanno and its modification by Liu was used to create standard esophageal burns with 50% NaOH. The study was performed with 76 rats in 4 main groups (sham, CAPE, EGF, and control) and 2 subgroups in each for 5 and 28 days of observation. Efficacy of treatment was assessed in 28-day subgroups by measuring weight gain, contrast esophagograms on day 27, histologic evaluation by measuring stenosis index (wall thickness/lumen diameter), and collagen deposition, and biochemically by determining tissue hydroxy proline (OHP) content.

RESULTS

In the end of the study, increase rates of mean body weights of the animals in the 28-day subgroups were as follows: sham, 30%; CAPE, 23%; EGF, 22%; and control, 14%. Although all the animals in subgroups significantly gained weight, the mean weight gain was significantly low in controls when compared with sham, CAPE, and EGF groups (P <.05). Contrast esophagograms on day 27 showed no stenosis in the sham, mild stenosis in CAPE and EGF, and severe stenosis with proximal dilatation in controls. Stenosis indices of the subgroups were as follows: sham, 0.29; CAPE, 0.41; EGF, 0.41; control, 0.84. Index was significantly higher in controls (P <.05). Collagen accumulation scores in the esophageal wall were as follows: Sham, 0.0; CAPE, 0.87; EGF, 0.30; control, 2.70. Scores also were significantly higher in controls (P <.05). Tissue (OHP) levels were as follows (mg/g dry tissue): Sham, 1.48; CAPE, 1.53; EGF, 1.90; control, 4.01. Production of OHP was significantly higher in controls.

CONCLUSIONS

The results of the parameters in the study indicate that administration of CAPE and EGF has beneficial effects in the prevention of caustic esophageal strictures. Those effects of CAPE may occur through its antiinflammatory, immunomodulatory, and antioxidant properties, and EGF may occur through its induced proliferative properties on the esophagus.

Involvement of oxidative stress in experimentally induced reflux esophagitis and Barrett's esophagus: clue for the chemoprevention of esophageal carcinoma by antioxidants

Oxidative damage has long been related to mucosal damages of gastrointestinal tracts and their ensuing carcinogenesis. In spite of treatment with anti-secretory medications for reflux esophagitis, considerable portions of patient did not achieve the complete mucosal healings or suffered from sustaining symptoms or development of dread complication like Barrett's esophagus, suggesting other damaging factors or impaired mucosal resistance are also involved in their pathogenesis. The present study was designed either to evaluate the oxidative stress as the major pathogenic factor of reflux esophagitis or to find out the usefulness of antioxidant in the treatment of reflux esophagitis and the prevention of development of Barrett's esophagus. Acute or chronic reflux esophagitis was induced through either narrowing the third portion of duodenal lumen or performing myotomy of lower esophageal sphincter in rats, respectively. DA-9601, a new phytopharmaceutical possessing antioxidative properties, significantly attenuated the gross and histopathologic scores of acute reflux esophagitis in a dose-dependent manner compared to those treated with ranitidine alone. Only scattered erosions were observed in antioxidant pre-treated group, but acid suppression by ranitidine was not so effective in decreasing the severity of reflux esophagitis. Significantly increased amounts of malondialdehyde (MDA), increased NF-kappa B activations, and depletions of reduced glutathione (GSH) were observed in experimentally induced reflux esophagitis, but DA-9601 pre-treatment attenuated the decrement of mucosal GSH levels and decreased MDA formations significantly. DA-9601 treatment showed significant reductions in the activation of NF-kappa B transcription factor. DA-9601 significantly decreased the proliferating cell nuclear antigen-labeling index (PCNA-LI) of esophagus (P<0.05) in chronic reflux esophagitis model and prevented the development of Barrett's esophagus. In conclusion, reflux esophagitis provoked considerable levels of oxidative stress in the esophageal mucosa. Antioxidant treatment seems to be the first line therapeutics in the prevention or treatment of reflux esophagitis. Moreover, antioxidant possibly played the chemopreventive role through preventing the development of Barrett's esophagus.

Assessing NSAID prescription use as a predisposing factor for gastroesophageal reflux disease in a Medicaid population

PURPOSE

The purpose of the study was to determine the incidence of GERD associated with prescription NSAID consumption.

METHODS

All Georgia Medicaid patients > 25 years of age and continuously eligible for 1996, 1997, and 1998 were included in the study. Patients were excluded if they received a GERD diagnoses during 1996 and 1997. Patients were observed in 1998 and classified into GERD and control cohorts. Comorbidities, demographics, and NSAID prescription consumption were retained and modeled with logistic regression.

RESULTS

The absolute risk of developing GERD without previous NSAID consumption was 0.38. The absolute risk of developing GERD for those patients who consumed one or more NSAID prescriptions during 1996 and 1997 was 0.80. Thus, the relative risk of GERD for NSAID patients was 2.11. GERD was significantly associated with one or more NSAID prescriptions (OR = 1.82), age (OR = 1.05 for 5 year range), gender (OR = 1.31 for females), asthma (OR = 3.24), obesity (OR = 2.77), hiatal hernia (OR = 4.17), tobacco use (OR = 2.56), and alcohol (OR = 1.83). The initial NSAID prescription was responsible for the greatest marginal increase in GERD.

CONCLUSIONS

Our study suggests that NSAIDs are associated with GERD especially for females, alcohol and tobacco users, and patients with asthma, hiatal hernia, or obesity.

Salivary and gastric epidermal growth factor in patients with Zollinger-Ellison syndrome: its protective potential

OBJECTIVE

Evidence is accumulating that epidermal growth factor (EGF) is a major molecule contributing to the maintenance of the integrity of the upper alimentary tract mucosa before and after injury by acid and pepsin. Patients with Zollinger-Ellison Syndrome (ZES) typically have hypersecretion of acid and pepsin; however, the concentration and rate of secretion of salivary and gastric EGF that could counteract these potentially aggressive factors are unknown. Accordingly, this study was conducted to determine whether EGF affords mucosal protection in ZES patients.

METHODS

The concentration and output of salivary (sEGF) and gastric epidermal growth factor (gEGF) were measured in eight patients with ZES and the results compared to those in 17 patients with nonulcer dyspepsia (NUD), serving as a control group. All patients had normal esophageal and gastric mucosa as determined by endoscopy. Total saliva was collected during 1-h parafilm- and 1-h pentagastrin/parafilm-stimulated conditions, as well as basal and pentagastrin-stimulated gastric juice. The concentration and output of EGF were determined by radioimmunoassay.

RESULTS

The concentration of EGF in saliva collected from ZES patients after parafilm chewing was significantly higher compared to that in NUD patients (4.61 +/- 0.59 vs 2.75 +/- 0.50 ng/ml, p < 0.05). The concentration of EGF in saliva collected after pentagastrin stimulation in ZES patients was also significantly higher than in NUD patients (4.37 +/- 0.73 vs 2.22 +/- 0.37 ng/ml, p < 0.05). Salivary EGF output during parafilm chewing in ZES and NUD were similar (68 +/- 6.4 vs 109 +/- 25.2 ng/h). Salivary EGF output after administration of pentagastrin in ZES and NUD was also similar (66 +/- 6.1 vs 132 +/- 45.4 ng/h). Basal EGF output in the gastric juice of patients with ZES was 3-fold higher than in patients with NUD (801 +/- 73 vs 271 +/- 32 ng/h, p < 0.01). Pentagastrin-stimulated EGF output was similar in both groups (705 +/- 92 vs 675 +/- 168 ng/h).

CONCLUSIONS

Patients with ZES have a significantly higher EGF concentration in saliva and EGF output in basal gastric juice. This elevated content of salivary and gastric EGF in ZES patients may play a protective role in preventing the development of reflux esophagitis and gastric ulcer under the impact of gastric acid and pepsin hypersecretion.

Experimental esophagitis induced by acid and pepsin in rabbits mimicking human reflux esophagitis

BACKGROUND & AIMS

The lack of appropriate animal models might explain the paucity of information on the mechanisms of mucosal damage and defense in reflux esophagitis. The aim of this study was to develop a model of esophagitis in rabbits mimicking human reflux esophagitis.

METHODS

New Zealand white rabbits underwent surgery for placement of a plastic tube into the cervical esophagus. Acidified pepsin (AP) was intermittently perfused for different periods. Esophageal injury was assessed by macroscopic and microscopic examination, including the cell proliferation immunohistochemical parameter mib1.

RESULTS

Rabbit losses (20%) were attributable mostly to postsurgical mortality and tube displacement. Perfusion of AP for 60 min/12 h or 45 min/12 h induced high-grade esophagitis by days 3 and 5, respectively, characterized by diffuse erosion/ulceration, inflammation, bleeding, and reactive epithelial changes. Perfusion of acidified pepsin for 60 min/day, especially at 30 min/12 h, induced low-grade esophagitis characterized by superficial epithelial loss, mild/absent inflammation, and epithelial reactive changes including increased cell proliferation, basal hyperplasia, and papillomatosis, which reached maximal expression by day 7. This perfusion regimen induced mucosal adaptation to damage.

CONCLUSIONS

Different and highly reproducible esophageal mucosal lesions mimicking human reflux esophagitis can be induced in rabbits with repetitive acid and pepsin exposure.

Esophageal motility and intraesophageal pH patterns in patients with esophagitis and chronic nonsteroidal anti-inflammatory drug use

Clinical reports suggest that nonsteroidal anti-inflammatory drugs (NSAIDs) use might induce esophageal symptoms and damage, including esophagitis, but experimental data are conflicting, and some indicate that NSAIDs improve mucosal damage. It is not known whether patients with endoscopically diagnosed esophagitis during NSAID use have different baseline reflux patterns from patients with reflux esophagitis and no NSAID use. Two groups of patients with and without chronic NSAID use and esophagitis were prospectively studied. Twenty-four-hour pH monitoring and esophageal manometry were performed in all patients who were free of NSAID and any other drug use during tests. Esophageal motility and reflux patterns did not differ in patients with esophagitis regardless of the presence or absence of NSAID use. However, the subgroup of patients with grades II and III esophagitis and chronic NSAID use had a significantly greater lower esophageal sphincter (LES) pressure and a less severe intraesophageal pH profile than patients without NSAID use. In agreement with clinical reports, these results suggest that NSAID use may aggravate an otherwise milder acid-related esophageal disease in a subgroup of patients.