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

Strongly acidic gastroesophageal reflux and esophageal lumen pH before and after esophageal lavage with water or two bicarbonate concentrations in anesthetized dogs

OBJECTIVE

To increase acidic esophageal lumen pH in dogs that developed gastroesophageal reflux (GER) during anesthesia. We compared water and 2 different bicarbonate concentrations.

ANIMALS

112 healthy, nonbrachycephalic dogs presented for ovariectomy.

PROCEDURES

Following standard anesthesia and surgery protocols for ovariectomy in all dogs, esophageal lumen impedance and pH were monitored using a dedicated probe. Esophageal impedance indicates the presence of GER whereas pH indicates the acidity level. Dogs with strongly acidic GER and an esophageal lumen pH value < 4.0 were included in the study, and lavage was performed with either tap water, bicarbonate 1%, or bicarbonate 2% until the pH increased to > 4.0. The effect of lavage on esophageal pH was compared using the Kruskal-Wallis and Wilcoxon 2 sample tests. Associations between lavage and pH changes were determined.

RESULTS

Of 48/112 dogs with strongly acidic GER, 33% neutralized their esophageal pH during surgery. For the 32 dogs that maintained an esophageal lumen pH value < 4, esophageal lavage with water increased the lumen pH to > 4 in 78.6% of dogs, whereas both bicarbonate concentrations increased it in 100% of the dogs to a more neutral pH (P < .0001). The dogs in the water group were more likely to regurgitate after anesthesia (36% vs 0% in both bicarbonate groups, P = .028).

CLINICAL RELEVANCE

Bicarbonate 1% and 2% increased esophageal lumen pH to more than 4 after strongly acidic GER. Lavage with water was mildly effective, but required large volumes and predisposed to further regurgitation after anesthesia.

Effect of two different pre-anaesthetic omeprazole protocols on gastroesophageal reflux incidence and pH in dogs

OBJECTIVES

Gastroesophageal reflux can occur during anaesthesia and may lead to esophagitis and occasionally oesophageal stricture formation. The aim of the study is to assess two omeprazole protocols on gastroesophageal reflux incidence and pH in anaesthetised dogs.

MATERIALS AND METHODS

Fifty-five dogs undergoing elective ovariectomy were randomly assigned to: omeprazole single dose 1 mg/kg orally the evening before anaesthesia (20 dogs), omeprazole two doses 1 mg/kg orally the evening and 3 hours before anaesthesia (15 dogs), and control group that did not receive omeprazole (20 dogs). An oesophageal impedance/pH probe was used to measure gastroesophageal reflux incidence and pH during anaesthesia.

RESULTS

Gastroesophageal reflux was observed in 55% (11/20) of control dogs, 55% (11/20) of dogs receiving omeprazole once and 47% (7/15) of dogs receiving omeprazole twice. The incidence was not statistically significant different between groups. Gastroesophageal reflux pH (mean ± sd) was higher in dogs receiving omeprazole twice (6.3 ± 1.5), when compared to either control dogs (3.8 ± 1.1) or dogs receiving omeprazole once (4.1 ± 1.5). Strongly acidic reflux (pH < 4) was observed in 7% (1/15) of dogs receiving omeprazole twice versus 55% (11/20) and 35% (7/20) of control dogs and dogs receiving omeprazole once, respectively.

CLINICAL SIGNIFICANCE

Omeprazole administered the evening and 3 hours before anaesthesia increased gastroesophageal reflux pH and decreased the incidence of strongly acidic reflux in dogs. A single dose of omeprazole given the evening before anaesthesia had no effect on reflux pH.

Protective and regenerative effects of a novel medical device against esophageal mucosal damage using in vitro and ex vivo models

Gastroesophageal reflux disease (GERD) is a common digestive disorder that causes esophagitis and injuries to the esophageal mucosa. GERD symptoms are recurrent during pregnancy and their treatment is focused on lifestyle changes and nonprescription medicines. The aim of this study was to characterize the mechanism of action of a new patented medical device, an oral formulation containing hyaluronic acid, rice extract, and amino acids dispersed in a bioadhesive polymer matrix, by assessing its protective effects in in vitro and ex vivo models of esophageal mucosa damage. Acidic bile salts and pepsin cocktail (BSC) added to CP-A and COLO-680 N esophagus cells were used as an in vitro GERD model to evaluate the binding capacities, anti-inflammatory effects and reparative properties of the investigational product (IP) in comparison to a viscous control. Our results showed that the IP prevents cell permeability and tight junction dysfunction induced by BSC. Furthermore, the IP was also able to down-regulate IL-6 and IL-8 mRNA expression induced by BSC stimulation and to promote tissue repair and wound healing. The results were confirmed by ex vivo experiments in excised rat esophagi through the quantification of Evans Blue permeability assay. These experiments provided evidence that the IP is able to bind to the human esophagus cells, preventing the damage caused by gastroesophageal reflux, showing potential anti-irritative, soothing, and reparative properties.

Prevalence of Gastroesophageal Reflux in Cats During Anesthesia and Effect of Omeprazole on Gastric pH

Background

Gastroesophageal reflux (GER) is poorly characterized in anesthetized cats, but can cause aspiration pneumonia, esophagitis, and esophageal stricture formation.

Objective

To determine whether pre‐anesthetic orally administered omeprazole increases gastric and esophageal pH and increases serum gastrin concentrations in anesthetized cats, and to determine the prevalence of GER using combined multichannel impedance and pH monitoring.

Animals

Twenty‐seven healthy cats undergoing elective dental procedures.

Methods

Prospective, double‐masked, placebo‐controlled, randomized clinical trial. Cats were randomized to receive 2 PO doses of omeprazole (1.45–2.20 mg/kg) or an empty gelatin capsule placebo 18–24 hours and 4 hours before anesthetic induction. Blood for measurement of serum gastrin concentration was collected during anesthetic induction. An esophageal pH/impedance catheter was utilized to continuously measure esophageal pH and detect GER throughout anesthesia.

Results

Mean gastric pH in the cats that received omeprazole was 7.2 ± 0.4 (range, 6.6–7.8) and was significantly higher than the pH in cats that received the placebo 2.8 ± 1.0 (range, 1.3–4.1; P < .001). Omeprazole administration was not associated with a significant increase in serum gastrin concentration (P = .616). Nine of 27 cats (33.3%) had ≥1 episode of GER during anesthesia.

Conclusions and Clinical Relevance

Pre‐anesthetic administration of 2 PO doses of omeprazole at a dosage of 1.45–2.20 mg/kg in cats was associated with a significant increase in gastric and esophageal pH within 24 hours, but was not associated with a significant increase in serum gastrin concentration. Prevalence of reflux events in cats during anesthesia was similar to that of dogs during anesthesia.

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.

Intraluminal acid activates esophageal nodose C fibers after mast cell activation

Acid reflux in the esophagus can induce esophageal painful sensations such as heartburn and noncardiac chest pain. The mechanisms underlying acid-induced esophageal nociception are not clearly understood. In our previous studies, we characterized esophageal vagal nociceptive afferents and defined their responses to noxious mechanical and chemical stimulation. In the present study, we aim to determine their responses to intraluminal acid infusion. Extracellular single-unit recordings were performed in nodose ganglion neurons with intact nerve endings in the esophagus using ex vivo esophageal-vagal preparations. Action potentials evoked by esophageal intraluminal acid perfusion were compared in naive and ovalbumin (OVA)-challenged animals, followed by measurements of transepithelial electrical resistance (TEER) and the expression of tight junction proteins (zona occludens-1 and occludin). In naive guinea pigs, intraluminal infusion with either acid (pH = 2-3) or capsaicin did not evoke an action potential discharge in esophageal nodose C fibers. In OVA-sensitized animals, following esophageal mast cell activation by in vivo OVA inhalation, intraluminal acid infusion for about 20 min started to evoke action potential discharges. This effect is further confirmed by selective mast cell activation using in vitro tissue OVA challenge in esophageal-vagal preparations. OVA inhalation leads to decreased TEER and zona occludens-1 expression, suggesting an impaired esophageal epithelial barrier function after mast cell activation. These data for the first time provide direct evidence of intraluminal acid-induced activation of esophageal nociceptive C fibers and suggest that mast cell activation may make esophageal epithelium more permeable to acid, which subsequently may increase esophageal vagal nociceptive C fiber activation.

Relationship between baseline impedance levels and esophageal mucosal integrity in children with erosive and non-erosive reflux disease

BACKGROUND

Baseline impedance measurement has been reported to be related to esophageal acid exposure and hypothesized to be a marker of microscopic changes of the esophageal mucosa. Aims of the study were to establish whether any relationship existed between the magnitude of intercellular space diameter (ISD) of esophageal mucosa and baseline impedance levels in children with gastro-esophageal reflux disease (GERD), and to compare baseline impedance levels between children with non erosive (NERD) and erosive (ERD) reflux disease.

METHODS

Fifteen children (median age: 11.2 years) with NERD, and 11 with ERD (median age: 9.6 years) were prospectively studied. All patients underwent upper endoscopy. Biopsies were taken 2-3cm above the Z-line, and ISD was measured using transmission electron microscopy. All patients underwent impedance pH-monitoring, and baseline impedance levels were assessed in the most distal impedance channel.

KEY RESULTS

Mean (±SD) ISD did not differ between NERD (1.0±0.3μm) and ERD (1.1 ± 0.3 μm, ns). Considering all patients together, no correlation was found between distal baseline impedance and ISD (r: -0.15; ns). Conversely, negative correlations were found between distal baseline impedance and acid exposure time (r: -0.76; P<0.001), long-lasting reflux episodes (r: -0.78; P<0.001), acid reflux episodes (r: -0.62; P<0.001), and acid clearance time (r: -0.79; P<0.001). Distal baseline impedance was significantly lower in ERD [1455 (947-2338) Ω] than in NERD children [3065 (2253-3771) Ω; P<0.01].

CONCLUSIONS & INFERENCES

  In children with GERD baseline impedance levels are not useful in predicting reflux-induced ultrastructural changes in the esophageal mucosa, despite their ability to discriminate between NERD and ERD.

Barrier effect of Esoxx(®) on esophageal mucosal damage: experimental study on ex-vivo swine model

The aim of the present study was to assess the potential barrier effect of Esoxx^®, a new nonprescription medication under development for the relief of gastroesophageal reflux symptoms. Esoxx is based on a mixture of hyaluronic acid and chondroitin sulfate in a bioadhesive suspension of Lutrol^® F 127 polymer (poloxamer 407) which facilitates the product adhesion on the esophageal mucosa. The mucosal damage was induced by 15 to 90 minutes of perfusion with an acidic solution (HCl, pH 1.47) with or without pepsin (2000 U/mL, acidified to pH 2; Sigma-Aldrich). Mucosal esophageal specimens were histologically evaluated and Evans blue dye solution was used to assess the permeability of the swine mucosa after the chemical injury. The results show that: (1) esophageal mucosal damage is related to the perfusion time and to the presence of pepsin, (2) mucosal damage is associated with an increased permeability, documented by an evident Evans blue staining, (3) perfusion with Esoxx is able to reduce the permeability of the injured mucosa, even after saline washing of the swine esophagus. These preliminary results support further clinical studies of Esoxx in the topical treatment of gastroesophageal reflux symptoms.

The influence of esomeprazole and cisapride on gastroesophageal reflux during anesthesia in dogs

BACKGROUND

Gastroesophageal reflux (GER) is common in anesthetized dogs and can cause esophagitis, esophageal stricture, and aspiration pneumonia.

OBJECTIVE

To determine whether preanesthetic IV administration of esomeprazole alone or esomeprazole and cisapride increases esophageal pH and decreases the frequency of GER in anesthetized dogs using combined multichannel impedance and pH monitoring.

ANIMALS

Sixty-one healthy dogs undergoing elective orthopedic surgery procedures.

METHODS

Prospective, randomized, placebo-controlled study. Dogs were randomized to receive IV saline (0.9% NaCl), esomeprazole (1 mg/kg) alone, or a combination of esomeprazole (1 mg/kg) and cisapride (1 mg/kg) 12-18 hours and 1-1.5 hours before anesthetic induction. An esophageal pH/impedance probe was utilized to measure esophageal pH and detect GER.

RESULTS

Eight of 21 dogs in the placebo group (38.1%), 8 of 22 dogs in the esomeprazole group (36%), and 2 of 18 dogs in the combined esomeprazole and cisapride group (11%) had ≥ 1 episode of GER on impedance testing during anesthesia (P < .05). Esomeprazole was associated with a significant increase in gastric and esophageal pH (P = .001), but the drug did not significantly decrease the frequency of GER (P = .955). Concurrent administration of cisapride was associated with a significant decrease in the number of reflux events (RE) compared to the placebo and esomeprazole groups (P < .05).

CONCLUSIONS AND CLINICAL RELEVANCE

Preanesthetic administration of cisapride and esomeprazole decreases the number of RE in anesthetized dogs, but administration of esomeprazole alone was associated with nonacid and weakly acidic reflux in all but 1 dog.

Effect of Helicobacter pylori infection on Barrett's esophagus and esophageal adenocarcinoma formation in a rat model of chronic gastroesophageal reflux

OBJECTIVES

To investigate the relationship between Helicobacter pylori infection and Barrett's esophagus (BE), a rat model of chronic gastroesophageal reflux with H. pylori infection was established and the degree of inflammation, incidence of BE and esophageal adenocarcinoma (EA) were evaluated.

METHODS

Eight-week-old male specific-pathogen-free SD rats were divided into five groups randomly: pseudo-operation group; esophagojejunum anastomosis (EJA) group; EJA with H. pylori infection group; EJA with H. pylori infection and celecoxib-treated group; EJA with celecoxib-treated group. Rats were kept for 30 weeks after surgery. Esophageal lesion was evaluated grossly and microscopically. The expression of COX-2 and CDX2 was determined by RT-PCR and immunohistochemistry staining. The level of PGE₂ was assessed by enzyme-linked immunosorbent assay.

RESULTS

Esophageal mucosal injury in the group of EJA with H. pylori infection was decreased than that in EJA group (p < .05). The incidence of BE and EA in rats undergoing EJA with H. pylori infection was increased than in rats undergoing EJA with no statistical difference. Celecoxib treatment decreased the incidence of EA in rats undergoing EJA with H. pylori infection (p < .05). The expression of CDX2 mRNA was decreased in rats with H. pylori infection or treated with celecoxib than in the rats of pseudo-operation group (p < .05). When compared with those in rats of pseudo-operation group, the expression of COX-2 mRNA and the level of PGE₂ were upregulated in rats undergoing EJA irrespective of H. pylori infection (p < .05) and downregulated in rats treated with celecoxib (p < .05). When H. pylori colonized in esophagus, the severity of inflammation and the incidence of BE and EA were increased significantly. Higher levels of COX-2 expression and PGE₂ were detected in rats with esophageal H. pylori colonization.

CONCLUSIONS

When H. pylori infect in stomach, it may reduce the severity of inflammation. However, when colonizes in esophagus, H. pylori increases the severity of esophageal inflammation and the incidence of BE and EA. Celecoxib administration attenuates the incidence of EA by inhibiting COX-2 expression.

Viewpoints on Acid-induced inflammatory mediators in esophageal mucosa

We have focused on understanding the onset of gastroesophageal reflux disease by examining the mucosal response to the presence of acid in the esophageal lumen. Upon exposure to HCl, inflammation of the esophagus begins with activation of the transient receptor potential channel vanilloid subfamily member-1 (TRPV1) in the mucosa, and production of IL-8, substance P (SP), calcitonin gene related peptide (CGRP) and platelet activating factor (PAF). Production of SP and CGRP, but not PAF, is abolished by the neural blocker tetrodotoxin suggesting that SP and CGRP are neurally released and that PAF arises from non neural pathways. Epithelial cells contain TRPV1 receptor mRNA and protein and respond to HCl and to the TRPV1 agonist capsaicin with production of PAF. PAF, SP and IL-8 act as chemokines, inducing migration of peripheral blood leukocytes. PAF and SP activate peripheral blood leukocytes inducing the production of H₂O₂. In circular muscle, PAF causes production of IL-6, and IL-6 causes production of additional H₂O₂, through activation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidases. Among these, NADPH oxidase 5 cDNA is significantly up-regulated by exposure to PAF; H₂O₂ content of esophageal and lower esophageal sphincter circular muscle is elevated in human esophagitis, causing dysfunction of esophageal circular muscle contraction and reduction in esophageal sphincter tone. Thus esophageal keratinocytes, that constitute the first barrier to the refluxate, may also serve as the initiating cell type in esophageal inflammation, secreting inflammatory mediators and pro-inflammatory cytokines and affecting leukocyte recruitment and activity.

HCl-induced inflammatory mediators in esophageal mucosa increase migration and production of H2O2 by peripheral blood leukocytes

Exposure of esophageal mucosa to hydrochloric acid (HCl) is a crucial factor in the pathogenesis of reflux disease. We examined supernatant of HCl-exposed rabbit mucosa for inflammatory mediators enhancing migration of leukocytes and production of H(2)O(2) as an indicator of leukocyte activation. A tubular segment of rabbit esophageal mucosa was tied at both ends to form a sac, which was filled with HCl-acidified Krebs buffer at pH 5 (or plain Krebs buffer as control) and kept oxygenated at 37 degrees C. The medium around the sac (supernatant) was collected after 3 h. Rabbit peripheral blood leukocytes (PBL) were isolated, and sac supernatant was used to investigate PBL migration and H(2)O(2) production. HCl-exposed esophageal mucosa released substance P (SP), CGRP, platelet-activating factor (PAF), and IL-8 into the supernatant. PBL migration increased in response to IL-8 or to supernatant of the HCl-filled mucosal sac. Supernatant-induced PBL migration was inhibited by IL-8 antibodies and by antagonists for PAF (CV3988) or neurokinin 1 (i.e., SP), but not by a CGRP antagonist. Supernatant of the HCl-filled mucosal sac increased H(2)O(2) release by PBL that was significantly reduced by CV3988 and by a SP antagonist but was not affected by IL-8 antibodies or by a CGRP antagonist. We conclude that IL-8, PAF, and SP are important inflammatory mediators released by esophageal mucosa in response to acid that promote PBL migration. In addition, PAF and SP induce production of H(2)O(2) by PBL. These findings provide a direct link between acid exposure and recruitment and activation of immune cells in esophageal mucosa.

Simulated reflux decreases vocal fold epithelial barrier resistance

OBJECTIVES/HYPOTHESIS

The vocal fold epithelium provides a barrier to the entry of inhaled and systemic challenges. However, the location of the epithelium makes it vulnerable to damage. Past research suggests, but does not directly demonstrate, that exposure to gastric reflux adversely affects the function of the epithelial barrier. Understanding the nature of reflux-induced epithelial barrier dysfunction is necessary to better recognize the mechanisms for vocal fold susceptibility to this disease. Therefore, we examined the effects of physiologically relevant reflux challenges on vocal fold transepithelial resistance and gross epithelial and subepithelial appearance.

STUDY DESIGN

Ex vivo, mixed design with between-group and repeated-measures analyses.

METHODS

Healthy, native porcine vocal folds (N = 52) were exposed to physiologically relevant acidic pepsin, acid-only, or pepsin-only challenges and examined with electrophysiology and light microscopy. For all challenges, vocal folds exposed to a neutral pH served as control.

RESULTS

Acidic pepsin and acid-only challenges, but not pepsin-only or control challenges significantly reduced transepithelial resistance within 30 minutes. Reductions in transepithelial resistance were irreversible. Challenge exposure produced minimal gross changes in vocal fold epithelial or subepithelial appearance as evidenced by light microscopy.

CONCLUSIONS

These findings demonstrate that acidic environments characteristic of gastric reflux compromise epithelial barrier function without gross structural changes. In healthy, native vocal folds, reductions in transepithelial resistance could reflect reflux-related epithelial disruption. These results might guide the development of pharmacologic and therapeutic recommendations for patients with reflux, such as continued acid-suppression therapy and patient antireflux behavioral education.

Lafutidine, a protective H₂ receptor antagonist, enhances mucosal defense in rat esophagus

BACKGROUND

Luminal acid or CO₂ induces a hyperemic response in the esophagus, via activation of acid sensors on capsaicin-sensitive afferent nerves (CSAN). Since disruption of the hyperemic response to luminal CO₂ acidifies the interstitium of the esophageal mucosa, the hyperemic response may maintain interstitial pH (pH(int)). We hypothesized that acid-related hyperemia maintains pH(int), preventing acid-induced injury in the esophageal mucosa.

METHODS

We examined the effects of capsaicin (Cap) or lafutidine (Laf), a mucosal protective H₂ antagonist, on the regulation of pH(int) and blood flow in rat esophagus using ratiometric microimaging and laser-Doppler measurements of the lower esophageal mucosa of living rats. The esophagus was topically superfused with pH 7.0 buffer, or a pH 1.0 or pH 1.0 + pepsin (1 mg/ml) solution with or without Laf.

RESULTS

Cap (30 or 100 µM) or Laf (0.1 or 1 mM) dose-dependently increased blood flow, accompanied by increased pH(int). The pH 1.0 solution increased blood flow without pH(int) change, whereas Laf (1 mM) increased blood flow and pH(int) during acid exposure. The effects of Laf were abolished by ablation of CSAN. Perfusion of the acidified pepsin solution gradually decreased pH(int), inhibited by Laf perfusion.

CONCLUSIONS

Activation of CSAN by Laf with or without acid, accompanied by hyperemia, increased pH(int), preventing acidified pepsin-induced interstitial acidification. Stimulation of the capsaicin pathway with compounds such as Laf enhances mucosal protection from acid-related injury in the upper gastrointestinal tract.

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.

Epithelial Na+ channel delta subunit is an acid sensor in the human oesophagus

Gastro-oesophageal reflux disease is caused by the reflux of gastric contents into the oesophagus, and thus the oesophageal lumen is damaged by gastric acid. The acid sensor involved in oesophageal epithelial defense is still unclear. Recently, we described that the epithelial Na(+) channel delta subunit (ENaCdelta) is a candidate molecule for a pH sensor in the human brain. Here, using reverse transcription-polymerase chain reaction and in situ hybridization methods, we showed that the proton-sensitive ENaCdelta was strongly expressed in the epithelial layer of the human oesophagus, representative peripheral tissue that can be exposed to an acidic environment. Other ENaC subunits (alpha, beta, and gamma) were also localized there. Based on the expression pattern, human oesophageal ENaC complex was mimicked in the Xenopus oocyte expression system and the response to acidic pH was recorded using a two-electrode voltage-clamp technique. The human oesophageal-mimicking ENaCdeltabetagammaalpha complex generated an amiloride-sensitive inward current at the holding potential of -60 mV. The ENaCdeltabetagammaalpha current was significantly activated by acidic pH (pH 4.0), approximately equal to the luminal value when gastric acid refluxes into the oesophagus. In conclusion, ENaCdelta is a candidate molecule for pH sensing in the gastrointestinal system in humans, providing a novel therapeutic target for gastro-oesophageal reflux 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.

Epithelial Na+ channel delta subunit mediates acid-induced ATP release in the human skin

The amiloride-sensitive epithelial Na(+) channel (ENaC) regulates Na(+) homeostasis in cells and across epithelia. Although we described that ENaCdelta is a candidate molecule for a pH sensor in the human brain, the physiological and pathological roles of ENaCdelta in non-neuronal tissues are still unknown. Here we show a novel physiological function of ENaCdelta in peripheral tissues in humans. Expression analyses at the level of mRNA clearly revealed that ENaCdelta was abundantly expressed in human epidermis and keratinocytes. In addition, ENaCdelta protein was detected in there. In cultured keratinocytes, acidic stress (pH 5.0) evoked ATP release, which was significantly reduced in the presence of 100 microM amiloride or 10 microM benzamil. In conclusion, ENaCdelta may be involved in the mechanism underlying pH sensing followed by the regulation of cell viability in the human skin.

Reactive oxygen species and chemokines: Are they elevated in the esophageal mucosa of children with gastroesophageal reflux disease?

AIM: To determine the role of inflammatory cytokines and reactive oxygen species (ROS) in childhood reflux esophagitis.

METHODS: A total of 59 subjects who had complaints suggesting GERD underwent esophagogastroduodenoscopy. Endoscopic and histopathologic diagnosis of reflux esophagitis was established by Savary-Miller and Vandenplas grading systems, respectively. Esophageal biopsy specimens were taken from the esophagus 20% proximal above the esophagogastric junction for conventional histopathological examination and the measurements of ROS and cytokine levels. ROS were measured by chemiluminescence, whereas IL-8 and MCP-1 levels were determined with quantitative immunometric ELISA on esophageal tissue. Esophageal tissue ROS, IL-8 and MCP-1 levels were compared among groups with and without endoscopic/histo-pathologic esophagitis.

RESULTS: Of 59 patients 28 (47.5%) had normal esophagus whereas 31 (52.5%) had endoscopic esophagitis. In histopathological evaluation, almost 73% of the cases had mild and 6.8% had moderate degree of esophagitis. When ROS and chemokine levels were compared among groups with and without endoscopic esophagitis, statistical difference could not be found between patients with and without esophagitis. Although the levels of ROS, IL-8 and MCP-1 were found to be higher in the group with histopathological reflux esophagitis, this difference was not statistically significant.

CONCLUSION: These results suggest that the grade of esophagitis is usually mild or moderate during childhood and factors apart from ROS, IL-8 and MCP-1 may be involved in the pathogenesis of reflux esophagitis in children.

Expression analysis of the epithelial Na+ channel delta subunit in human melanoma G-361 cells

Malignant melanoma is the most deadly form of skin cancer and its incidence is steadily increasing worldwide. The plasma membrane in melanoma cells possesses a variety of ion channels, so its profile is thought to lead to a novel target for medical treatment for malignant melanoma. Here we showed that human melanoma G-361 cells expressed the epithelial Na(+) channel delta subunit (ENaC delta), which is largely unknown in physiological and pathological functions in non-neuronal tissues. Expression analyses at the level of mRNA clearly revealed that ENaC delta transcript was strongly expressed in human melanoma cells using reverse transcription-polymerase chain reaction and cell-based in situ hybridization techniques. Other ENaC subunits (alpha, beta, and gamma) were also distributed in human melanoma cells. In addition, human melanoma cells possessed an abundant expression of ENaC delta protein by immunocytochemistry. These results provide an attractive target for drug development of malignant melanoma.

Effects of long-term cyclo-oxygenase 2 selective and acid inhibition on Barrett's oesophagus

BACKGROUND

There is an overexpression of cyclo-oxygenase 2 (COX-2) in Barrett's oesophagus (BO).

AIM

To determine the long-term effect of a COX-2 inhibitor on cellular mechanisms involved in BO.

METHODS

A randomized controlled trial was conducted in BO patients allocated to continue the usual proton pump inhibitor (PPI) alone treatment, or PPI combined with rofecoxib (25 mg/day) for 6 months. Cell proliferation index and COX-2 expression in BO glands was determined in biopsy specimens at baseline and after treatment. Cell apoptosis, cyclin D1, p53 and vascular endothelial growth factor (VEGF) expression was also explored in a subset of patients. Student-t test and the U-Mann-Whitney test were used for quantitative and ordinal variables.

RESULTS

Of 62 patients, 58 completed the study. A higher proportion of patients on rofecoxib + PPI exhibited a decrease in COX-2 expression compared to those treated with PPI alone, but cell proliferation index was not affected. Unlike PPI alone, rofecoxib + PPI was associated with an increase in the apoptotic cell index, a decrease in p53 cell staining and VEGF expression in mucosal vessels. No effect on low-grade dysplasia or cyclin D1 was observed.

CONCLUSIONS

The addition of rofecoxib to PPI therapy does not affect cell proliferation index in BO cells after 6 months of therapy, but does reduce COX-2 and VEGF expression and increases cell apoptosis.

Immune and Inflammatory Responses in GERD and Lansoprazole

The exact pathophysiological mechanisms responsible for gastroesophageal reflux disease (GERD) remain unclear. Recent studies have shown that mucosal immune and inflammatory responses, characterized by specific cytokine and chemokine profiles, may underlie the diverse esophageal phenotypes of GERD. Interleukin 8 (IL-8), a representative chemokine, mediates neutrophil trafficking via its receptors, mainly CXCR-1. The IL-8 mRNA and protein levels are increased in the esophageal mucosa, not only in reflux esophagitis (RE), but also in endoscopy-negative GERD (NERD), through activation of nuclear factor-kappaB (NF-kappaB), which is a pivotal transcription factor. Mucosal IL-8 concentrations have been found to parallel the endoscopic severity of RE, implying that this cytokine is a key player in the development of GERD. The mucosal levels of the C-C chemokines, macrophage chemoattractant protein 1 (MCP-1) and regulated on activation normal T-cell-expressed and presumably secreted (RANTES), which primarily attract monocytes and lymphocytes to the site of inflammation, respectively, are also elevated in RE. The secreted levels of IL-8 and IL-1beta, a prototype of proinflammatory cytokine, are maximal at the proximal segment within Barrett esophagus (BE) tissue. The expression of the two pleiotrophic proinflammatory cytokines, IL-6 and tumor necrosis factor alpha, is enhanced in the intestinal epithelium of BE, which places this epithelium at a higher risk for developing malignancy. BE is characterized by a distinct Th-2 predominant cytokine profile (IL-4 and -10), compared to the proinflammatory nature of RE (interferone-gamma). Treatment with a proton pump inhibitor, lansoprazole reduces the mucosal levels of IL-8 mRNA and protein in GERD, including RE and NERD. This may occur in part through an anti-inflammatory action of proton pump inhibitors beyond gastric acid inhibition.

Endoscopic appearance of GERD: putative role of cell proliferation

BACKGROUND

Erosive esophagitis is a frequent endoscopic feature in patients with gastro-oesophageal reflux disease. However, most of patients with heartburn/regurgitation have a non-erosive reflux disease. The reason for this heterogeneous impact of gastro-oesophageal reflux disease on oesophageal mucosa is unknown to date.

AIM

To evaluate the cell proliferation status of oesophageal epithelium in both healthy normal subjects and patients with gastro-oesophageal reflux disease with or without erosions.

MATERIALS AND METHODS

All the subjects underwent endoscopy and biopsies were taken at 5 cm from the squamo-columnar junction. Specimens were analysed both at histology and at transmission electron microscopy. Cell proliferation was evaluated by MIB1 immunostaining. Of the 85 subjects were studied, 10 were healthy controls with normal pH-testing and macroscopical, histological and ultrastructural patterns; 37 were patients with erosive esophagitis, and 38 patients with non-erosive reflux disease.

RESULTS

At histology, of the 37 patients affected by erosive esophagitis, 30 had normal mucosa and 7 showed mild oesophagitis. One patient with non-erosive reflux disease showed signs of oesophagitis at histology. At TEM, all patients with gastro-oesophageal reflux disease had ultrastructural patterns of damage i.e. dilations of intercellular spaces (DIS), and all controls had a normal ultrastructural pattern. The mean (+/-SD) MIB1-LI values of normal subjects and non-erosive reflux disease and erosive oesophagitis patients were 62.2% (+/-9.1), 29.7% (+/-7.2) and 16.2% (+/-5.2), respectively; there were significant differences among the three groups (p<0.001).

CONCLUSIONS

Oesophageal mucosa of patients with reflux symptoms presents a decrease in MIB1 immunostaining of 50% and 25% in non-erosive reflux disease and erosive esophagitis patients with respect to normal subjects.

Gastroesophageal reflux disease-associated esophagitis induces endogenous cytokine production leading to motor abnormalities

BACKGROUND & AIMS

Gastroesophageal reflux disease is a condition frequently associated with esophagitis and motor abnormalities. Recent evidence suggests that proinflammatory cytokines, such as interleukin (IL)-1beta and IL-6, may be implicated because they reduce esophageal muscle contractility, but these results derive from in vitro or animal models of esophagitis. This study used human esophageal cells and tissues to identify the cellular source of cytokines in human esophagitis investigate whether cytokines can be induced by gastric refluxate, and examine whether esophageal tissue- or cell-derived mediators affect muscle contractility.

METHODS

Endoscopic mucosal biopsy specimens were obtained from patients with and without esophagitis, organ-cultured, and undernatants were assessed for cytokine content. The cytokine profile of esophageal epithelial, fibroblast, and muscle cells was analyzed, and esophageal mucosa and cell products were tested in an esophageal circular muscle contraction assay.

RESULTS

The mucosa of esophagitis patients produced significantly greater amounts of IL-1beta and IL-6 compared with those of control patients. Cultured esophageal epithelial cells produced IL-6, as did fibroblasts and muscle cells. Epithelial cells exposed to buffered, but not denatured, gastric juice produced IL-6. Undernatants of mucosal biopsy cultures from esophagitis patients reduced esophageal muscle contraction, as did supernatants from esophageal epithelial cell cultures.

CONCLUSIONS

The human esophagus produces cytokines capable of reducing contractility of esophageal muscle cells. Exposure to gastric juice is sufficient to stimulate esophageal epithelial cells to produce IL-6, a cytokine able to alter esophageal contractility. These results indicate that classic cytokines are important mediators of the motor disturbances associated with human esophageal inflammation.

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.

A novel external esophageal perfusion model for reflux esophageal injury

The current animal models of esophagitis and Barrett's esophagus consist of surgeries that divert the gastroduodenal contents to the esophagus. The limitations of these models are the inability to control the amount and concentration of the refluxate and the causing of significant postoperative stress and morbidity. Eighteen adult rats were cannulated at the upper esophagus and connected to a subcutaneous osmotic micropump to perfuse the esophageal lumen with bile and acid. Animals were sacrificed after 7 days of perfusion. Histological changes were determined. Cell proliferation, apoptosis, lipid peroxidation, and glutathione were measured. Histopathological changes in the bile- or acid-perfused esophagus were consistent with the findings associated with reflux esophagitis. Enhanced proliferation and apoptosis were seen, along with increased oxidative stress. The external esophageal perfusion model enabled precise control of the injurious agent. It induced the histologic and cellular injury of reflux esophagitis after 7 days.

Laryngeal epithelial defenses against laryngopharyngeal reflux: investigations of E-cadherin, carbonic anhydrase isoenzyme III, and pepsin

OBJECTIVES

This is the third annual report of an international research network studying the cellular impact of laryngopharyngeal reflux (LPR) on laryngeal epithelium. The objective of this study was to investigate the presence of E-cadherin (epithelial cadherin; the intercellular junctional complex protein) in relation to the presence of (intracellular) pepsin and carbonic anhydrase isoenzyme III (CAIII).

METHODS

Fifty-four laryngeal biopsy specimens from 18 LPR patients were studied by immunohistochemistry and Western blotting for pepsin, E-cadherin, and CAIII. These data were compared to those from normal control subjects analyzed in another research study.

RESULTS

Intracellular pepsin was detected in LPR patients, but not in controls. E-cadherin expression was reduced in patients with LPR. Carbonic anhydrase III expression was not found in the vocal fold or in the majority of samples taken from the ventricle of LPR patients and was inversely associated with E-cadherin membranous expression.

CONCLUSIONS

The findings of depleted E-cadherin and CAIII and the presence of pepsin appear to correlate with LPR. The reduced protective response indicated by the reduced expression of CAIII may play an important role in the disruption of the intercellular barrier associated with the down-regulation of E-cadherin.

Systemic phosphatidylcholine pretreatment protects canine esophageal mucosa during acute experimental biliary reflux

AIM: To characterize the consequences of short-term exposure to luminal bile on mucosal mast cell reactions in a canine model, and to determine the effects of systemic phosphatidylcholine pretreatment in this condition.

METHODS: Twenty mongrel dogs were used for experiments. Group 1 (n  = 5) served as a saline-treated control, while in group 2 (n = 5) the esophagus was exposed to bile for 3 h. In group 3 (n  = 5) the animals were pretreated with 7-nitroindazole to inhibit the neuronal isoform of nitric oxide synthase. In group 4 (n  = 5) phosphatidylcholine solution (50 mg/kg) was administered iv before the biliary challenge. Mucosal microcirculation was observed by intravital videomicroscopy. Myeloperoxidase and nitric oxide synthase activities, the degrees of mast cell degranulation and mucosal damage were evaluated via tissue biopsies.

RESULTS: Exposure to bile evoked significant mast cell degranulation and leukocyte accumulation. The red blood cell velocity and the diameter of the postcapillary venules increased significantly. The tissue ATP content and constitutive nitric oxide synthase activity decreased, while the inducible nitric oxide synthase activity increased significantly as compared to the control values. 7-nitroindazole treatment significantly exacerbated the mucosal mast cell degranulation and tissue damage. In contrast, phosphatidylcholine pretreatment prevented the bile-induced ATP depletion, the inducible nitric oxide synthase and myeloperoxidase activity and the mast cell degranulation increased.

CONCLUSION: The neuronal nitric oxide synthase - mast cell axis plays an important role in the esophageal mucosal defense system. Systemic phosphatidylcholine pretreatment affords effective protection through ameliorating the bile-induced ATP depletion and secondary inflammatory reaction.

Characterisation of adherens and tight junctional molecules in normal animal larynx; determining a suitable model for studying molecular abnormalities in human laryngopharyngeal reflux

BACKGROUND

The disruption of intercellular junctions in the larynx is a pathological feature of laryngopharyngeal reflux (LPR). Good experimental models are necessary to gain greater insight into the molecular mechanisms and alterations that result from abnormal exposure of the laryngeal epithelium to acid refluxate.

AIMS

To characterise laryngeal tissues from different species to determine the most suitable for use in experimental studies of LPR.

METHODS

Human and non-human laryngeal tissues (mouse, rat, guinea pig, porcine, and rabbit) were studied. Histological characterisation was performed by light microscopy. The expression and subcellular localisation of adherens junctional molecules (E-cadherin and beta catenin) was evaluated by immunohistochemistry, and tight junction molecules (occludin and zonula occludens 1 (ZO-1)) by western blotting. The ultrastructural features of porcine and human tissue were assessed by electron microscopy.

RESULTS

Porcine tissue revealed both respiratory-type and stratified squamous epithelium, as seen in the human larynx. The expression and subcellular localisation of the E-cadherin-catenin complex was detected in all species except mouse and rat. The pattern of ZO-1 and occludin expression was preserved in all species.

CONCLUSION

The expression of intercellular junctional complexes in porcine epithelium is similar to that seen in humans. These results confirm the suitability of these species to study molecular mechanisms of LPR in an experimental system.

Functional oesophageal epithelial defense against acid

Functional oesophageal epithelial defense, including cell proliferation, restitution, buffers and ion transporters, plays a significant role in maintaining mucosal integrity and enabling rapid repair after injury. Growth factors such as epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF) are associated with oesophageal epithelial proliferation or restitution. Na+/H+ exchanger-1, an ion transporter, regulates intracellular pH and cell volume, and may have roles in cell proliferation, migration and survival. Cytokine, adhesion molecules, cyclooxygenase-2 and free radicals are associated with oesophageal inflammation and breach of the functional epithelial defense. Although the oesophagus does not have strong functional epithelial defense against acid, this defensive mechanisms may be involved in the pathogenesis of non-erosive gastro-oesophageal reflux disease. Medical therapy may be developed in future to enhance functional oesophageal epithelial defense.

Altered localization and expression of tight-junction proteins in a rat model with chronic acid reflux esophagitis

BACKGROUND

The esophageal tight junction is responsible for the paracellular sealing of the epithelium. Alteration of the expression of tight-junction proteins plays crucial roles in the pathogenesis of some human diseases. The aim of this study was to investigate the distribution and expression pattern of tight-junction proteins in the esophageal mucosa of control rats and rats with reflux esophagitis.

METHODS

Chronic acid reflux esophagitis was experimentally induced by operation in rats. The animals were killed on days 7 and 14 after the operation. The thickness of the mucosa and the 5-bromo-2-deoxyuridine (BrdU) labeling index were assessed. The expression pattern of the tight-junction proteins claudin 1-4 and occludin in the esophageal mucosa was investigated by immunofluorescence staining and Western blotting in the controls and esophagitis rats.

RESULTS

In the esophagitis model, the thickness and BrdU labeling index increased with time. In control rats, claudin-1, -3, and -4 were localized on the cellular membranes of esophageal epithelial cells, mainly in the spinous and granular layers, while claudin-2 was not detected in any layer. Occludin was seen on the cellular membranes in all esophageal mucosal layers. In the esophagitis rats, the expression of claudin-1 was increased both in the plasma membrane and in the cytoplasm around the erosion in the spinous and granular layers. The expression of claudin-4 and occludin shifted to the cytoplasm from the plasma membrane in the spinous and granular layers. In contrast, the expression of claudin-3 was decreased in the spinous and granular layers.

CONCLUSIONS

The localization and the expression patterns of tight-junction proteins were different in the controls and the rat esophagitis model. The expression of claudin-3 in the esophageal mucosa was decreased, while that of claudin-1 was increased. It is postulated that these alterations in tight-junction proteins most likely increase the permeability of the esophageal the epithelium, thereby impairing the defense mechanism of this epithelium.

Expression of CXC receptor 1 and 2 in esophageal mucosa of patients with reflux esophagitis

AIM: Interleukin 8 (IL-8) mediates neutrophil trafficking via its receptors. Recent studies have shown that IL-8 is likely involved in the development and progression of erosive reflux esophagitis (RE), yet little is known about the two distinct receptors, CXC receptor (CXCR)-1 and -2. The purpose of this study was to determine CXCR-1 and -2 messenger RNA expression levels in RE.

METHODS: We studied 26 patients with RE and 15 asymptomatic controls. Paired biopsy samples were taken from the esophagus 3 cm above the gastroesophageal junction; one biopsy was snap frozen for measurement of CXCR-1 and -2 mRNA levels by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR), and another was formalin-fixed for histopathological evaluation. We also examined the association of the expression levels of CXCR-1 and -2 mRNA with histopathological hallmarks of RE.

RESULTS: The relative CXCR-1 and -2 mRNA expression levels were rather decreased in esophageal mucosa of patients with RE, compared to those in normal esophagus of controls. There were no significant difference in the relative mRNA expression levels of CXCR-1 and -2 among endoscopic grades of RE based on the Los Angeles classification. Each histopathological hallmark of GERD was not associated with the expression levels of CXCR-1 and -2 mRNA.

CONCLUSION: Apart from overexpression of IL-8, the relative expression levels of CXCR-1 and -2 mRNA were rather lower than expected in the affected esophageal mucosa of patients with RE.

Expression and localization of c-Fos and NOS in the central nerve system following esophageal acid stimulation in rats

AIM

To determine the distribution of neurons expressing c-Fos and nitric oxide synthase (NOS) in the central nerve system (CNS) following esophageal acid exposure, and to investigate the relationship between c-Fos and NOS.

METHODS

Twelve Wistar rats were randomly divided into two equal groups. Hydrochloric acid with pepsin was perfused in the lower part of the esophagus for 60 min. As a control, normal saline was used. Thirty minutes after the perfusion, the rats were killed and brains were removed and processed for c-Fos immunohistochemistry and NADPH-d histochemistry. Blood pressure (BP), heart rate (HR), and respiratory rate (RR) during the experimental procedures were recorded every 10 min.

RESULTS

There were no significant differences in BP, HR and RR between the two groups. c-Fos immunoreactivity was significantly increased in rats receiving acid plus pepsin perfusion in amygdala (AM), paraventricular nucleus (PVN), parabrachial nucleus (PBN), nucleus tractus solitarius and dorsal motor nucleus of vagus (NTS/DMV), nucleus ambiguous (NA), reticular nucleus of medulla (RNM) and area postrema (AP). NOS reactivity in this group was significantly increased in PVN, PBN, NTS/DMV, RNM and AP. c-Fos and NOS had significant correlation between PVN, PBN, NTS/DMV, RNM and AP.

CONCLUSION

Acid plus pepsin perfusion of the esophagus results in neural activation in areas of CNS, and NO is likely one of the neurotransmitters in some of these areas.

Enhanced expression of interleukin-8 and activation of nuclear factor kappa-B in endoscopy-negative gastroesophageal reflux disease

OBJECTIVE

Interleukin-8 (IL-8) mediates neutrophil trafficking via its receptors. Recent studies have shown that IL-8 is likely involved in the development and progression of erosive reflux esophagitis (RE), yet little is known about its implication in endoscopy-negative gastroesophageal reflux disease (GERD). The purpose of this study was to determine IL-8 messenger ribonucleic acid (mRNA) expression levels in endoscopy-negative GERD, along with assessment of nuclear factor kappaB (NF-kappaB) activation, which upregulates IL-8 expression.

METHODS

We studied 31 patients with endoscopy-negative GERD, 15 patients with erosive RE, and 15 asymptomatic controls. Paired biopsy samples were taken from the esophagus 3 cm above the gastroesophageal junction; one biopsy was snap-frozen for measurement of IL-8 mRNA levels by real-time quantitative polymerase chain reaction, and another was formalin-fixed for histopathological evaluation. In nine endoscopy-negative GERD patients, the IL-8 mRNA expression levels were measured before and 8 wk after treatment with lansoprazole. We also sampled additional specimens for NF-kappaB-DNA binding assay and immunohistochemical analyses of NF-kappaB p65 and p50 subunits, IL-8 and specific IL-8 receptor, CXCR-1.

RESULTS

The relative IL-8 mRNA expression levels were significantly higher in esophageal mucosa of patients with endoscopy-negative GERD than those of the controls. The presence of basal zone hyperplasia and intraepithelial neutrophils, histopathological hallmarks of GERD, were associated with higher levels of IL-8 mRNA. Lansoprazole treatment significantly reduced the IL-8 mRNA expression levels. The esophageal epithelium of patients with GERD showed intense immunoreactivity for IL-8, and expressed CXCR-1 antigen. We found NF-kappaB activation in esophageal mucosa in GERD patients and the NF-kappaB subunits were localized predominantly in the nuclei of IL-8-expressing cells.

CONCLUSIONS

Our results demonstrate enhanced mucosal expression of IL-8 in incipient GERD even without mucosal breaks. NF-kappaB activation may be implicated in the pathogenesis in GERD.

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.

Elevated levels of chemokines in esophageal mucosa of patients with reflux esophagitis

OBJECTIVE

Chemokines play a key role in the pathogenesis of various inflammatory conditions. However, there is little information on their profile in reflux esophagitis (RE). We sought to study esophageal mucosa levels of chemokines in RE.

METHODS

A total of 32 outpatients with RE and 13 normal controls were studied. Endoscopic severity of RE was classified according to the Los Angeles grading system. Paired biopsy specimens were taken from the esophagus 3 cm above the gastroesophageal junction; one biopsy was snap frozen for measurement of mucosal levels of interleukin 8 (IL-8), monocyte chemoattractant protein 1 (MCP-1), regulated on activation normal T-cell expressed and presumably secreted (RANTES), and IL-1 beta by enzyme linked immunosorbent assays, while the other was formalin-fixed for histopathological evaluation.

RESULTS

IL-8, MCP-1, and RANTES levels were significantly higher in esophageal mucosa of RE patients than those of the controls. IL-8 levels correlated significantly with the endoscopic severity of RE. Basal zone hyperplasia and papillary elongation, histopathological hallmarks of RE, were both associated with higher levels of IL-8 and MCP-1. The presence of intraepithelial neutrophils and eosinophils, which also indicate RE, was associated with high levels of IL-8 and RANTES, respectively. There were no significant differences in IL-1 beta levels between the RE and control groups, but IL-1 beta levels correlated significantly with the IL-8 production. Again, the IL-8 levels were significantly decreased after lansoprazole treatment.

CONCLUSION

Our results indicate that chemokines produced locally in the esophageal mucosa may be involved in the development and progression of RE.

Selective COX-2 inhibition is associated with decreased mucosal damage induced by acid and pepsin in rabbit esophagitis

OBJECTIVE

To evaluate the effects of COX-1 and/or COX-2 inhibition in a model of chronic esophagitis in rabbits.

METHODS

Both high- and low-grade esophagitis were induced in rabbits by the perfusion of acidified pepsin. Rabbits were treated with either a selective COX-2 inhibitor (DFU[3-(3-Fluorophenyl)-4-(4-Methanesulfonyl)-5,5-Dimethyl-5H-Furan-2-One];30 mg/Kg/day), a nonspecific COX inhibitor (indomethacin; 2 mg/Kg/day), or a COX-1 preferential inhibitor (piroxicam; 2 mg/Kg/12 h).

RESULTS

Prostaglandins are derived from COX-1 activity in the normal esophagus. Both low- and high-grade esophagitis are associated with a progressive increase of COX activity, which is partially dependent on the COX-2 isoform. DFU reduced muscosal damage in both models of esophagitis. However, indomethacin did not affect significantly mucosal damage, and piroxicam increased damage in low-grade esophagitis.

CONCLUSIONS

COX-1 activity is constitutive in the rabbit esophageal mucosa, but both COX-2 and COX-1 activity are increased under the impact of acidified pepsin. Treatment with the COX-2 inhibitor DFU is associated with improvement of mucosal damage, which may have therapeutic implications.

Treatment and prevention of aspirin-induced gastroduodenal ulcers and gastrointestinal bleeding

Aspirin use is associated with gastroduodenal mucosal damage and increased risk of upper gastrointestinal (GI) bleeding. Many aspirin users should receive prophylactic treatment since they often have several risk factors for upper GI complications. The best therapeutic approach for reducing GI toxicity in low-dose aspirin users is still ill-defined as only a few studies have focused on this problem. Omeprazole appears to be very effective in reducing both acute gastroduodenal mucosal damage and upper GI bleeding in the high-risk patient taking low-dose aspirin, but data with other anti-ulcer agents are lacking (misoprostol) or inconsistent (ranitidine) at present. The role of Helicobacter pylori is controversial in NSAID users, but there is now wide agreement that H. pylori infection increases mucosal damage and the risk of upper GI bleeding in low-dose aspirin users.

Use of MIB-1 in the assessment of esophageal biopsy specimens from patients with gastroesophageal reflux disease in well- and poorly oriented areas

MIB-1, a proliferation marker may be useful in the assessment of esophageal biopsy specimens for gastroesophageal reflux disease (GERD). Forty-five hematoxylin and eosin-stained esophageal biopsy specimens were histologically assessed for basal zone height, papillary length, and inflammatory cell infiltrate and classified as 10 normal and 35 esophagitis. The percentage of MIB-1-positive area (MIB-1% area) was measured on immunostained sections using image analysis (CAS 200) in the basal half of well-oriented areas and adjacent to five cross-sectioned papillae (c-pap) in poorly oriented areas. The cell layer of the MIB-1-positive cell furthest from the basal layer of the c-pap was also noted. MIB-1% area was significantly greater in both well- and poorly oriented areas of esophagitis biopsy specimens compared with normal biopsy specimens. MIB-1 positivity in the basal half and c-pap were correlated (r = 0.43, p = 0.017). MIB-1 expression correlated with basal zone height and eosinophil infiltrate (r = 0.61, p < 0.001; r = 0.32, p = 0.03, respectively). The cell layer with positive cells furthest from c-pap in normal and esophagitis biopsy specimens was two and six layers, respectively. Using 31% as a threshold to detect abnormal findings, the MIB-1 sensitivity/specificity and positive predictive value in the basal half and c-pap were 86, 70, 91% and 80, 80, 94%, respectively. In summary, MIB-1 staining correlates with basal zone hyperplasia and eosinophil infiltrate seen in GERD. MIB-1 staining can be assessed both in well- and poorly oriented areas as MIB-1% areas. Alternatively simply finding MIB-1 positive cells more than three cell layers from the basal layer is abnormal and consistent with GERD.

Effect of hydrochloric acid, pepsin, or taurocholate on bioelectric properties of gastric squamous mucosa in horses

OBJECTIVE

To determine the effect of pH with or without pepsin or taurocholic acid on the bioelectric properties of gastric squamous mucosa in horses.

SAMPLE POPULATION

Gastric tissues obtained from 16 adult horses that did not have evidence of gastric disease.

PROCEDURE

Bioelectric properties of squamous mucosa were determined, using modified Ussing chambers. Tissues then were exposed to mucosal pepsin (1 mg/ml) or taurocholic acid (2.5 mM) under neutral (pH 74) or acidic (pH 1.7) conditions.

RESULTS

Exposure of mucosal sheets to an acidic pH resulted in an immediate and sustained decrease in transmembrane potential difference and calculated tissue resistance. Pepsin or taurocholic acid did not significantly affect bioelectric variables when added to a mucosal bath solution of pH 7.4. A synergistic effect between pepsin or taurocholic acid and mucosal acidification was not detected.

CONCLUSIONS AND CLINICAL RELEVANCE

Mucosal acidification with or without pepsin or taurocholic acid resulted in reduced tissue resistance. These data support the contention that squamous erosions or ulcers in horses are mediated, in part, by prolonged exposure of gastric squamous mucosa to luminal acid.

Esophageal ulceration activates keratinocyte growth factor and its receptor in rats: implications for ulcer healing

BACKGROUND & AIMS

Cellular and molecular mechanisms of esophageal ulcer healing remain unexplored. We studied the sequential cellular events and the expression of keratinocyte growth factor (KGF) and its receptor (KGF-R) during the healing of experimental esophageal ulcers.

METHODS

Esophageal ulcers were produced in rats by local application of acetic acid. Studies included (1) ulcer size, (2) quantitative histology, and (3) KGF and KGF-R messenger RNA and protein expression by reverse-transcription polymerase chain reaction, Western blotting, and immunostaining. In separate groups, ulcer size and esophageal epithelial proliferation were evaluated after a single injection of recombinant human KGF (1 mg/kg) around the ulcer.

RESULTS

Ulcers were fully developed 3 days after induction, and 58% of ulcers were re-epithelialized by 9 days. At 3 days, in esophageal tissue bordering the ulcers, KGF messenger RNA and protein were increased by 191% and 151%, respectively, and KGF-R messenger RNA and protein were increased by 357% and 237%, respectively. KGF was expressed in stromal cells, whereas KGF-R was expressed in epithelial cells. At 6 days, epithelial proliferation at the ulcer margin was increased by 216%, and treatment with KGF further enhanced cell proliferation and accelerated ulcer healing.

CONCLUSIONS

KGF is a likely mediator of esophageal epithelial proliferation and ulcer healing.

Helicobacter pylori, NSAIDs and gastrointestinal haemorrhage

Helicobacter pylori infection and nonsteroidal anti-inflammatory drugs (NSAIDs) cause the majority of bleeding ulcers. Whether the presence of H. pylori infection would affect the risk of ulcers in patients taking NSAIDs is important for both theoretical and practical reasons. However, the results have been so conflicting that there is no consensus on the management of patients requiring NSAIDs who are infected with H. pylori. The controversy is largely due to the variable study design and marked heterogeneity of the study population. Studying the interaction between H. pylori and NSAIDs without considering these factors often leads to erroneous conclusions. Current evidence suggests that H. pylori contributes to an increased ulcer risk for patients who are about to start NSAID treatment, whereas NSAIDs probably account for the majority of ulcer disease in patients who are already taking long-term NSAIDs. In the light of the reduced gastric toxicity of COX-2 inhibitors, the relative importance of H. pylori in the pathogenesis of ulcers is expected to increase. Furthermore, recent evidence suggests that H. pylori contributes to ulcer bleeding associated with low-dose aspirin. Among H. pylori-positive patients with a history of ulcer bleeding who are taking low-dose aspirin, the eradication of H. pylori has been shown to be comparable to omeprazole in preventing recurrent bleeding.

Reliability, validity, and responsiveness of severity of dyspepsia assessment (SODA) in a randomized clinical trial of a COX-2-specific inhibitor and traditional NSAID therapy

OBJECTIVES

We aimed to assess the Severity of Dyspepsia Assessment (SODA) scales as measures of change in dyspepsia-related health in a blinded, randomized, controlled trial in arthritis patients treated with nonsteroidal anti-inflammatory drugs.

METHODS

Three thousand nine hundred seven arthritis patients completed SODA at baseline and weeks 4, 13, 26, and 52 and/or at early termination. Using baseline and 4-wk data, reliability was evaluated with Cronbach's a and the intraclass correlation coefficient (ICC). Dyspepsia adverse events were defined based on a combined set of World Health Organization Adverse Reaction Terminology terms. The ability of SODA to measure change in dyspepsia-related health was evaluated by comparing SODA change scores by dyspepsia adverse event severity level and withdrawal status. Responsiveness was further evaluated by the area under the curve (AUC) from receiver operating characteristic curves using withdrawal due to dyspepsia as the criterion.

RESULTS

The SODA scales--Pain Intensity (alpha = 0.93), Non Pain Symptoms (alpha = 0.82), and Satisfaction (alpha = 0.89)--demonstrated excellent internal consistency reliability using baseline data. Reproducibility was fair to good: Pain Intensity ICC = 0.49, Non Pain Symptoms ICC = 0.61, and Satisfaction ICC = 0.45. SODA change scores (4-wk score - baseline score) increased, or worsened, with increasing dyspepsia severity and differentiated between adjacent levels of dyspepsia severity for eight of nine adjacent comparisons (p < 0.05). SODA change scores also differentiated between those who did and did not withdraw (p < 0.001). Responsiveness was highest with the Pain Intensity scale (AUC = 0.78), followed by the Non Pain Symptoms (AUC = 0.74) and Satisfaction (AUC = 0.75) scales.

CONCLUSIONS

SODA is a reliable, valid instrument for use as a measure of dyspepsia tolerability in future clinical trials involving cyclo-oxygenase-2-specific and/or traditional nonsteroidal anti-inflammatory drugs.

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.

Nonsteroidal anti-inflammatory drugs, low-dose aspirin, and potential ways of reducing the risk of complications

Use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with an annual incidence of 1-2% of gastrointestinal (GI) complications, which may be fatal in some cases. Low-dose aspirin is also associated with an increased risk of upper GI bleeding, but the increase is about three times lower than that found with common NSAIDs. Misoprostol (600-800 microg/day) reduces the incidence of complications in non-aspirin NSAID users. Co-therapy with antisecretory drugs (proton pump inhibitors, PPIs) also reduces the risk of GI bleeding in high-risk patients taking NSAIDs and/or low-dose aspirin. Another way of reducing the incidence of GI complications is to use the highly selective cyclo-oxygenase 2 (COX-2) inhibitors. The GI safety of nitric oxide NSAIDs (NO-NSAIDs) has been demonstrated extensively in experimental conditions and preliminary clinical studies. Epidemiological studies have also shown that nitric oxide donor drugs reduce the risk of upper GI bleeding, which might be important in patients receiving low-dose aspirin.

Acid, helicobacter and immunity: a new paradigm for oesophagogastric cancer

Epidemiological evidence has clearly shown a highly significant relationship between Helicobacter pylori infection and the development of duodenal ulcer and distal gastric adenocarcinoma. Despite H. pylori being a common aetiological factor for both disorders, the two disease phenotypes are virtually mutually exclusive. This indicates that the host response to infection has a pivotal role in determining outcome; these disease phenotypes relate to the effect of infection on gastric acid secretion, duodenal ulcer being closely related to sustained acid secretion whereas gastric cancer follows gastric atrophy and impaired gastric acid secretion. Cancer at the oesophageal junction and that associated with Barrett's oesophagus is now the most rapidly increasing tumour in the gastrointestinal tract. The challenge for the next millennium, therefore, is to try and develop methods for identifying patients at risk of developing oesophagogastric cancer. A common feature in the pathogenesis of both gastric and oesophageal adenocarcinoma is inflammation presenting clinically as gastritis and oesophagitis. The pathway from gastritis to gastric atrophy, dysplasia and carcinoma is thought to be a multi-step process, probably triggered by free radicals within the gastric epithelium and increased exposure to luminal carcinogens. However, it has been unclear as to which aspect of the host response determines whether an individual will move along the neoplasia pathway. Recent work has shown that qualitative aspects of the immune environment in the stomach may account for a substantial part of the phenotypic divergence following H. pylori infection. Interleukin-1 beta polymorphisms relate closely to the propensity for an individual to develop distal gastric cancer and maybe useful for predicting risk in family members. In Barrett's oesophagus, we have recently shown that the immune environment may also be important in determining whether an individual will develop cancer. Although we did not find that Barrett's oesophagus was a profoundly inflammatory condition (unlike esophagitis in the squamous epithelium), where there was evidence of inflammation it was qualitatively different from that of oesophagitis in that a Th-2 response with increased expression of IL-4 predominated in Barrett's, whereas a Th-1 proinflammatory response characterised oesophagitis in squamous epithelium. It seems likely that the specific immune environment within Barrett's metaplasia may be an important driver towards dysplasia and carcinoma. Thus, the immune environment in the stomach and esophagus may be critical in determining whether an individual is at risk of developing neoplastic complications of H. pylori infection and gastroesophageal reflux. Identification of the genetic factors which underpin these responses may ultimately result in development of methods to identify individuals at high risk.