Mixed reflux of gastric and duodenal juices is more harmful to the esophagus than gastric juice alone. The need for surgical therapy re-emphasized

Cyclooxygenase-2 (COX-2) in carcinogenesis and selective COX-2 inhibitors for chemoprevention in gastrointestinal cancers

INTRODUCTION

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been reported to have a property to inhibit tumor development in some cancers while it shows various side effects such as gastrointestinal bleeding and renal disorder. Selective cyclooxygenase (COX)-2 inhibitors (coxibs) were originally developed as one of anti-inflammatory drugs to avoid side effect of NSAIDs. Fortunately, the coxibs was also proved to have an inhibiting effect on tumorigenesis by many experimental studies using cell lines and animal models like NSAIDs.

DISCUSSION

Since a randomized study for polyp chemoprevention by celecoxib in familial adenomatous polyposis (FAP) patients demonstrated a significant reduction in the number of colorectal polyps, the clinical use of celecoxib was approved for FAP patients. Three large trials using celecoxib (the Adenoma Prevention with Celebrex and the Prevention of Spontaneous Adenomatopus Polyps) or refecoxib (the Adenomatous Polyp Prevention on Vioxx) for the recurrence of colorectal polyps in patients with a history of colorectal adenoma polypectomized confirmed chemopreventive effects on colorectal adenoma but two of three trails alerted us a hazard of cardiovascular (CV) events. Thereafter, some coxibs were withdrawn from the market because they showed to increase risk of serious CV events including heart attacks and strokes. But recent reports concluded that a merit of the reduction in gastrointestinal events by coxibs exceeded a demerit of the increase in serious CV events. In this review, a role of COX-2 in carcinogenesis of gastrointestinal tract and a future of coxibs for chemoprevention are discussed.

Barrett's esophagus: pathogenesis, treatment, and prevention

Esophageal adenocarcinoma is the most common type of esophageal cancer seen in the United States and Western Europe. Barrett's esophagus (BE) is a well-known risk factor for esophageal adenocarcinoma and is believed to be found in 6% to 12% of patients undergoing endoscopy for gastroesophageal reflux disease and in more than 1% of all patients undergoing endoscopy. This article focuses on the pathogenesis, treatment, and prevention of BE.

The effect of oral administration of ursodeoxycholic acid and high-dose proton pump inhibitors on the histology of Barrett's esophagus

Bile acids may play a role in the pathogenesis of Barrett's esophagus (BE). Bile composition can be influenced by oral administration of ursodeoxycholic acid (UDCA). We prospectively investigated the effect of proton pump inhibitors (PPI) supplemented with UDCA in vivo in patients with BE. Patients with no or low-grade dysplasia who were clinically asymptomatic on PPI were eligible for the study. In order to exclude the effects of acid reflux, all patients were initially treated with 40 mg esomeprazole (ESO) twice daily for 6 months and continued on this dose till the end of the study (t = 12 months). During a period of 6 months (t = 6 month - t = 12 month) patients were treated with oral UDCA (600 mg twice daily). Patients underwent endoscopy at t = 0 months, t = 6 months and t = 12 months with multiple biopsies of the distal and proximal BE segment, normal squamous and gastric cardia. In addition, pH was measured at t = 0 months and t = 6 months using a BRAVO wireless pH capsule. Bile was sampled at the beginning of the UDCA treatment and 6 months later (t = 6 month and t = 12 month). All biopsies were reviewed for the extent of metaplasia, dysplasia, and acute and chronic inflammation. In addition, proliferation (Ki67), differentiation (villin, cytokeratins 7 and 20) and inflammation (COX-2) were investigated by immunohistochemistry (IHC). Nine patients (mean age 60 years, median BE length 7 cm) were included, of whom six had no dysplasia and three had low-grade dysplasia. pH measurements revealed a normal acid exposure in most patients at t = 0 and t = 6 months. In addition, bile composition analysis demonstrated the efficacy of UDCA. Combining the results of both phases of the study, no significant changes were seen in any of the histological or IHC parameters. Differentiation and proliferation parameters showed no significant changes. In this study, in BE patients who were clinically asymptomatic on PPI, increasing the PPI dose to the maximum for 6 months followed by the addition of UDCA for 6 months did not result in significant histological or IHC changes in their BE.

Effect of cholecystectomy on gastric and esophageal bile reflux in patients with upper gastrointestinal symptoms

Epidemiologic data have shown that cholecystectomy is associated with a moderately increased risk of esophageal adenocarcinoma. The study objective was to evaluate the role of refluxed bile. A total of 696 patients with upper gastrointestinal symptoms were included in the study, of whom 55 had a history of cholecystectomy (CHE). Bilirubin exposure was measured in percent time above absorbance 0.25 in the stomach and above 0.14 in the esophagus. Total gastric and esophageal bilirubin exposure was similar in both groups. Supine gastric bile reflux was slightly increased after cholecystectomy (30.6 +/- 30.2 vs. CHE: 37.1 +/- 29.5, P < 0.05). In patients with erosive esophagitis or Barrett's esophagus, there were differences in total gastric exposure (24.3 +/- 22.6 vs. CHE: 36.7 +/- 26.8, P < 0.05) but not in esophageal exposure. Cholecystectomy slightly augments bile reflux into the stomach without detectable differences in the esophagus. Therefore, increased esophageal bile reflux following cholecystectomy as a potential cause for the associated cancer risk could not be substantiated.

Carcinogenesis in reflux disease--in search for bile-specific effects

Bile reflux may play a key role for esophageal carcinogenesis in reflux disease. In search for bile-specific effects, the animal model of esophageal cancer was applied in a mutagenesis assay. Big Blue transgenic mice were operated with microsurgical techniques. Seven had total gastrectomy with esophagojejunostomy creating esophageal reflux of bile and five had a sham operation. After 24 weeks, the mutation frequency (MF) was measured through standard Big Blue mutagenesis assay in the esophageal mucosa and the duodenum as control. Esophageal reflux resulted in esophagitis in the distal esophagus. The MF in esophageal mucosa was 1.6 times higher in animals with reflux than in sham-operated animals; it was identical in the duodenum. In conclusion, the mutagenic potential of bile reflux has been confirmed. However, mechanisms of carcinogenesis in the esophageal cancer model other than chronic inflammation could not be identified because of the only moderately increased MF.

Sulindac prevents esophageal adenocarcinomas induced by gastroduodenal reflux in rats

PURPOSE

It is known that cyclooxygenase (COX)-2 expression is increased in Barrett's esophagus and esophageal adenocarcinomas. We studied COX-2 expression and the effect sulindac has on the genesis of Barrett's esophagus and adenocarcinoma in rats undergoing esophagogastroduodenal anastomosis (EGDA).

MATERIALS AND METHODS

Fifty-one rats were divided into a control group (n=27), a 500 ppm sulindac-treated group (n=15) and 1000 ppm sulindac-treated group (n=9). Randomly selected rats were killed by diethyl ether inhalation at 20 and 40 weeks after surgery.

RESULTS

At 40 weeks, rats treated with 1000 ppm sulindac showed narrower esophageal diameter and milder inflammation than the control rats. At 40 weeks, the incidence of Barrett's esophagus was similar between control and sulindac-treated groups, but the incidence of adenocarcinoma was significantly lower in the 1000 ppm sulindac-treated group than either the control or 500 ppm sulindac-treated groups. COX-2 was significantly increased in the lower esophagus of control rats killed at 40 weeks. Cyclin D1 expression was negligible in the sulindac- treated group compared with the control group.

CONCLUSION

We suggest that the chemopreventive effect of sulindac is related to decreased COX-2 and cyclin D1 expression, which may be influenced by reduced inflammation.

Prevalence and topography of intestinal metaplasia in columnar lined esophagus

OBJECTIVES

Barrett's mucosa is considered as a mosaic of three epithelial types but little is known about the topography of intestinal metaplasia in columnar lined esophagus. The aims of the study were to determine the prevalence of intestinal metaplasia within long and short segments of columnar lined esophagus and to analyze the distribution of the intestinal metaplasia within long segments of Barrett's esophagus.

PATIENTS AND METHODS

The study was performed on the initial endoscopy carried out among 112 patients enrolled in an endoscopic surveillance program. Seventy-two patients with columnar mucosa extending more than 3 cm into the esophagus (group I) and 40 patients with a short segment of columnar mucosa (group II) had multiple biopsies according to a standardized protocol. 1163 biopsies were analyzed on the whole: 949 biopsies in group I and 214 biopsies in group II.

RESULTS

Intestinal metaplasia was identified among 650 (68.5%) and 50 (23.4%) biopsies in groups I and II respectively (P<10-7). The proportion of biopsies with foci of intestinal metaplasia increased significantly with the length of the columnar mucosa. The diagnosis of Barrett's esophagus was confirmed in 100% of the patients in group I and in 45% of the patients in group II. In long segments of Barrett's esophagus, intestinal metaplasia was more frequently observed in the 2 upper thirds of the columnar mucosa that in the lower third (P<10-7). Detailed mapping of the distribution of epithelial types within the columnar lined esophagus identified three patterns of distribution of intestinal metaplasia within long segments of Barrett's esophagus: unifocal, multifocal and diffuse, in 5%, 56% and 39% of the patients respectively. Dysplasia was present in 15% of patients with long segments of Barrett's esophagus and 11% of patients with short segments (NS).

CONCLUSION

The distribution of intestinal metaplasia within columnar lined esophagus is heterogeneous and three distinct patterns can be identified: unifocal, multifocal and diffuse. Considering the risk of sampling error, the current recommendations concerning the biopsy protocols are mandatory until the validation of new techniques such as chromoendoscopy or magnifying endoscopy.

Ten-Year Follow up after Laparoscopic Nissen Fundoplication for Gastroesophageal Reflux Disease

Laparoscopic Nissen fundoplication was first undertaken in the early 1990s. Appreciable numbers of patients with 10-year follow up are only now available. This study assesses long-term outcome and durability of outcome after laparoscopic Nissen fundoplication for treatment of gastro-esophageal reflux disease. Since 1991, 829 patients have undergone laparoscopic fundoplications and are prospectively followed. Two hundred thirty-nine patients, 44 per cent male, with a median age of 53 years (± 15 standard deviation) underwent laparoscopic Nissen fundoplications at least 10 years ago; 28 (12%) patients were “redo” fundoplications. Before and after fundoplication, among many symptoms, patients scored the frequency and severity of dysphagia, chest pain, vomiting, regurgitation, choking, and heartburn using a Likert scale (0 = never/not bothersome to 10 = always/very bothersome). Symptom scores before versus after fundoplication were compared using a Wilcoxon matched-pairs test. Data are reported as median, mean ± standard deviation, when appropriate. After fundoplication, length of stay was 2 days, 3 days ± 4.8. Intra-operative inadvertent events were uncommon and without sequela: 1 esophagotomy, 1 gastrotomy, 3 cardiac dysrhythmias, and 3 CO2 pneumothoraces. Complications after fundoplication included: 1 postpneumonic empyema, 3 urinary retentions, 2 superficial wound infections, 1 urinary tract infection, 1 ileus, and 1 intraabdominal abscess. There were two perioperative deaths; 88 per cent of the patients are still alive. After laparoscopic Nissen fundoplication, frequency and severity scores dramatically improved for all symptoms queried (P < 0.001), especially for heartburn frequency (8, 8 ± 3.2 versus 2, 3 ± 2.8, P < 0.001) and severity (10, 8 ± 2.9 versus 1, 2 ± 2.5, P < 0.001). Eighty per cent of patients rate their symptoms as almost completely resolved or greatly improved, and 85 per cent note they would again have the laparoscopic fundoplication as a result of analysis of our initial experience, thereby promoting superior outcomes in the future. Nonetheless, follow up at 10 years and beyond of our initial experience documents that laparoscopic fundoplication durably provides high patient satisfaction resulting from long-term amelioration of the frequency and severity of symptoms of gastroesophageal reflux disease. These results promote further application of laparoscopic Nissen fundoplication.

The effect of antireflux surgery on esophageal carcinogenesis in patients with barrett esophagus: a systematic review

OBJECTIVE

To determine whether patients with Barrett esophagus who undergo antireflux surgery differ from medically treated patients in incidence of esophageal adenocarcinoma and probability of disease regression/progression.

SUMMARY BACKGROUND DATA

Barrett esophagus is a risk factor for the development of esophageal adenocarcinoma. A question exists as to whether antireflux surgery reduces this risk.

METHODS

Query of PubMed (1966 through October 2005) using predetermined search terms revealed 2011 abstracts, of which 100 full-text articles were reviewed. Twenty-five articles met selection criteria. A review of article references and consultation with experts revealed additional articles for inclusion. Studies that enrolled adults with biopsy-proven Barrett esophagus, specified treatment-type rendered, followed up patients with endoscopic biopsies no less than12 months of instituting therapy, and provided adequate extractable data. The incidence of adenocarcinoma and the proportion of patients developing progression or regression of Barrett esophagus and/or dysplasia were extracted.

RESULTS

In surgical and medical groups, 700 and 996 patients were followed for a total of 2939 and 3711 patient-years, respectively. The incidence rate of esophageal adenocarcinoma was 2.8 (95% confidence interval, 1.2-5.3) per 1000 patient-years among surgically treated patients and 6.3 (3.6-10.1) among medically treated patients (P = 0.034). Heterogeneity in incidence rates in surgically treated patients was observed between controlled studies and case series (P = 0.014). Among controlled studies, incidence rates were 4.8 (1.7-11.1) and 6.5 (2.6-13.8) per 1000 patient-years in surgical and medical patients, respectively (P = 0.320). Probability of progression was 2.9% (1.2-5.5) in surgical patients and 6.8% (2.6-12.1) in medical patients (P = 0.054). Probability of regression was 15.4% (6.1-31.4) in surgical patients and 1.9% (0.4-7.3) in medical patients (P = 0.004).

CONCLUSIONS

Antireflux surgery is associated with regression of Barrett esophagus and/or dysplasia. However, evidence suggesting that surgery reduces the incidence of adenocarcinoma is largely driven by uncontrolled studies.

Bile acids in combination with low pH induce oxidative stress and oxidative DNA damage: relevance to the pathogenesis of Barrett's oesophagus

BACKGROUND

Barrett's oesophagus is a premalignant condition associated with an increased risk for the development of oesophageal adenocarcinoma (ADCA). Previous studies indicated that oxidative damage contributes to the development of ADCA.

OBJECTIVE

To test the hypothesis that bile acids and gastric acid, two components of refluxate, can induce oxidative stress and oxidative DNA damage.

METHODS

Oxidative stress was evaluated by staining Barrett's oesophagus tissues with different degrees of dysplasia with 8-hydroxy-deoxyguanosine (8-OH-dG) antibody. The levels of 8-OH-dG were also evaluated ex vivo in Barrett's oesophagus tissues incubated for 10 min with control medium and medium acidified to pH 4 and supplemented with 0.5 mM bile acid cocktail. Furthermore, three oesophageal cell lines (Seg-1 cells, Barrett's oesophagus cells and HET-1A cells) were exposed to control media, media containing 0.1 mM bile acid cocktail, media acidified to pH 4, and media at pH 4 supplemented with 0.1 mM bile acid cocktail, and evaluated for induction of reactive oxygen species (ROS).

RESULTS

Immunohistochemical analysis showed that 8-OH-dG is formed mainly in the epithelial cells in dysplastic Barrett's oesophagus. Importantly, incubation of Barrett's oesophagus tissues with the combination of bile acid cocktail and acid leads to increased formation of 8-OH-dG. An increase in ROS in oesophageal cells was detected after exposure to pH 4 and bile acid cocktail.

CONCLUSIONS

Oxidative stress and oxidative DNA damage can be induced in oesophageal tissues and cells by short exposures to bile acids and low pH. These alterations may underlie the development of Barrett's oesophagus and tumour progression.

Bile acids and total bilirubin detection in saliva of patients submitted to gastric surgery and in particular to subtotal Billroth II resection

OBJECTIVE

The aim of our study was to detect bile acids and total bilirubin in saliva of gastrectomized patients, to confirm objectively presence of biliary laryngopharyngeal reflux and its relationship with laryngeal mucosa damage.

SUMMARY BACKGROUND DATA

Recently, it has been hypothesized that biliary-reflux may reach the upper aerodigestive tract and enhance development of laryngeal malignancies; nevertheless, the presence of duodenogastric contents in this region has never been revealed.

METHODS

We carried out a prospective observational case-control study on 52 patients (cases) previously submitted to gastric surgery, mainly to subtotal Billroth II resection, and on 51 healthy volunteers (controls). Patients were submitted to clinical interview, esophagogastroduodenal endoscopy, endoscopic laryngeal evaluation, and saliva collection. In all saliva samples, bile acids, total bilirubin, and pepsinogen II were assayed.

RESULTS

In cases, group bile acids levels were recorded in 17 of 52 (32.6%) patients, while in 35 of 52 (67.4%) they were undetectable. All controls were negative to bile acids. In positive cases to bile acids, we found a significant (P < 0.05) correlation between bile acids, total bilirubin, and pepsinogen II values and a significant (P < 0.05) higher prevalence of symptoms and findings of laryngeal damage and of previous laryngeal neoplastic lesions.

CONCLUSIONS

We found detectable levels of bile acids and total bilirubin in saliva of patients submitted to previous gastric surgery, prospecting an intriguing diagnostic role of this dosage in the study of biliary laryngopharyngeal reflux. We finally revealed a high incidence of laryngeal disorders in patients with positive bile acids in saliva.

Do acid and bile reflux into the esophagus simultaneously? Temporal relationship between duodenogastro-esophageal reflux and esophageal pH

BACKGROUND

Duodenogastro-esophageal reflux (DGER) is an important factor in the pathogenesis of reflux esophagitis. Animal studies have demonstrated that the injurious effect of duodenal juice components depends on pH. The purpose of the present study was to investigate the temporal relationship between DGER and esophageal pH.

METHODS

Seventy-six children with symptoms of gastro-esophageal reflux disease (27 without, 31 with mild, 18 with severe esophagitis) underwent 24 h simultaneous esophageal pH and bilirubin monitoring with Bilitec 2000. The recordings were analyzed for (i) pH at the beginning of DGER episodes; (ii) relative duration of DGER in eight defined pH intervals of 1 pH unit; and (iii) differences in relative duration of DGER between the three groups of children.

RESULTS

DGER episodes most frequently began at pH between 6 and 7. DGER was present in the esophagus across the spectrum of esophageal pH, with the biggest relative duration between pH 3 and 5. However, in children without esophagitis relative duration of DGER was longest between pH 5 and 6, in children with mild esophagitis between pH 4 and 5, while in those with severe esophagitis it was between pH 2 and 4 (P < 0.001).

CONCLUSIONS

DGER appears across the whole esophageal pH spectrum. The more severe the esophagitis, the lower the pH at which DGER occurs, resulting in simultaneous damaging effects of acid and duodenal juice components.

Duodeno-gastric-esophageal reflux--what is pathologic? Comparison of patients with Barrett's esophagus and age-matched volunteers

INTRODUCTION

The aim of the study was to analyse pH- and bile-monitoring data in patients with Barrett's esophagus and in age- and gender-matched controls.

SUBJECTS AND METHODS

Twenty-four consecutive Barrett's patients (8 females, 16 males, mean age 57 years), 21 patients with esophagitis (10 females, 11 males, mean age 58 years), and 19 healthy controls (8 females, 11 males, mean age 51 years), were included. Only patients underwent endoscopy with biopsy. All groups were investigated with manometry, gastric and esophageal 24-h pH, and simultaneous bile monitoring according to a standardized protocol. A bilirubin absorption>0.25 was determined as noxious bile reflux. The receiver operator characteristic (ROC) method was applied to determine the optimal cutoff value of pathologic bilirubin levels.

RESULTS

Of Barrett's patients, 79% had pathologic acidic gastric reflux (pH<4>5% of total measuring time). However, 32% of healthy controls also had acid reflux (p<0.05) without any symptoms. The median of esophageal bile reflux was 7.8% (lower quartile (LQ)-upper quartile (UQ)=1.6-17.8%) in Barrett's patients, in patients with esophagitis, 3.5% (LQ-UQ=0.1-13.5), and in contrast to 0% (LQ-UQ=0-1.0%) in controls, p=0.001. ROC analysis showed the optimal dividing value for patients at more than 1% bile reflux over 24 h (75% sensitivity, 84% specificity).

CONCLUSION

An optimal threshold to differentiate between normal and pathological bile reflux into the esophagus is 1% (24-h bile monitoring with an absorbance>0.25).

Cytogenetic characterization and gene expression profiling in the rat reflux-induced esophageal tumor model

OBJECTIVES

The reasons for the increasing incidence of esophageal adenocarcinoma are not clear. A causal relation between gastroesophageal reflux disease and esophageal adenocarcinoma has been suggested. Support for this comes from the development of esophageal adenocarcinoma in the rat reflux model. However, to date, no systematic characterization of the tumors derived from this model has been reported.

METHODS

We induced biliary reflux by creating esophagojejunal anastomoses in 12 Sprague-Dawley rats. The experiment was terminated at 9 months, and rat esophagi were harvested for histopathologic documentation of reflux-associated changes and evidence of tumor formation. Three cell lines were established from 2 of the reflux-associated tumors. We tested the ability of these cells to grow in vitro in tissue culture and in vivo as xenografts in an orthotopic location at the gastroesophageal junction. Furthermore, we performed a cytogenetic analysis and determined the array-based gene expression profiles of these 3 rodent carcinoma lines compared with normal esophageal mucosa.

RESULTS

At 9 months, 12 of 12 rodents had histologic features of metaplastic columnar epithelium in the esophagus, with 7 having invasive carcinomas with glandular differentiation (either adenocarcinomas or adenosquamous carcinomas). The 3 cell lines established from 2 reflux-associated tumors were capable of sustained in vitro propagation and grew successfully as xenografts in both subcutaneous and orthotopic locations, confirming the tumorigenic nature of these lines. Despite their establishment from primary tumors with glandular features, the histology of the xenografts was that of well-differentiated squamous carcinomas. Karyotype analyses demonstrated cytogenetic heterogeneity and aneuploidy; furthermore, translocation (7:11) was present in all 3 lines. Array-based gene expression profiling confirmed upregulation of several cancer-related genes important in human esophageal cancer. Quantitative reverse transcription-polymerase chain reaction was used to confirm the differential expression of selected transcripts (vascular endothelial growth factor [VEGF], polo-like kinases [PLK], cyclin dependent kinase 4 [CDK4], hypoxia-inducible factor 1alpha [HIF1alpha], and insulin-like growth factor 1 [IGF-1]) in comparison with nonneoplastic esophageal mucosal scrapings.

CONCLUSIONS

The rodent reflux model is capable of inducing metaplastic epithelial changes simulating Barrett esophagus, as well as subsequent neoplastic transformation, at a high frequency. Cell lines have been established from these tumors that are capable of in vitro and in vivo passaging. The rodent reflux model should be a valuable model for studying therapy and chemoprevention efforts for Barrett esophagus, whereas the established cell lines provide a useful resource for drug discovery and other high-throughput studies.

Molecular biologic staging of esophageal cancer

The molecular biology of esophageal cancer is characterized by a series of genetic mutations that occur throughout the progression from normal squamous epithelium to carcinoma. The most important risk factor for the development of adenocarcinoma, which is increasing in incidence, is the presence of CLE. The pathophysiology of CLE appears to be related to duodenogastroesophageal reflux, also increasing in incidence. The genetic mutations that are responsible for tumorigenesis have been described, although the precise sequence of mutations is variable. Analysis of molecular biologic factors that are important in tumorigenesis may be used in clinical applications: establishing diagnosis, assessing prognosis, and assigning therapy. The development of molecular biologic substaging of patients with CLE may potentially identify patients with elevated malignant potential and expedite therapy. The ability of molecular markers to predict resistance to chemotherapy and radiation therapy represents an important potential advantage, with two possible applications. Predictable resistance to a particular chemotherapeutic agent would allow the selection of a alternative agent, with a greater potential for efficacy. Furthermore, known mechanisms of resistance, which have been analyzed using molecular markers, may be inhibited or reversed. The molecular biology of esophageal cancer requires further study. The molecular events and factors that are involved may be important in the diagnosis, staging, and treatment of esophageal cancer, in addition to the description of tumorigenesis.

Bile acids and Barrett's oesophagus: a sine qua non or coincidence?

BACKGROUND

Barrett's oesophagus (BO), a premalignant condition associated with the development of oesophageal adenocarcinoma (OAC), is thought to be a consequence of chronic duodeno-gastro-oesophageal reflux. Of the refluxates, bile acids, either alone or in combination with acid, are probably the most important.

METHODS

Analysis of the literature on the role played by bile acids in inducing BO and/or progression to OAC.

RESULTS

Combined pH and Bilitec 2000 (as a measure of bile reflux) monitoring and oesophageal aspiration studies in humans suggest a combined role for bile acids, particularly taurine conjugated bile acids, in causing oesophageal mucosal injury. Evidence from animal models has demonstrated that duodenal juice alone is also able to induce BO and/or OAC. Likewise, ex vivo studies with biopsies from BO patients show that increased proliferation and cyclo-oxygenase-2 expression are present after a pulsed exposure to acid or conjugated bile acids, but not if acid and bile acids are combined. Proton-pump inhibitors (PPIs) have been shown to decrease the biliary component of the refluxate. There is some evidence that PPIs are able to reduce neoplastic progression in BO. On the other hand, chronic PPIs can also stimulate bacterial overgrowth, which can result in increased production of secondary bile acids, particularly deoxycholic acid, in the stomach. Deoxycholic acid has been demonstrated to have a tumour-promoting capacity.

CONCLUSIONS

It is unknown what factors of the refluxate (acid and/or bile) induce BO and/or promote carcinogenesis, but there is evidence that secondary bile acids play a role. A better understanding of the molecular steps involved in the induction of BO, and the role of bile acids herein, may identify targets at which preventive therapies can be directed.

Importance of duodenogastric reflux in gastro-oesophageal reflux disease

BACKGROUND

Bile in the oesophagus occurs frequently in patients with gastro-oesophageal reflux disease (GORD) and has been linked to Barrett's metaplasia and cancer. Although duodenogastric reflux is a prerequisite for bile in the oesophagus, little is known about its importance in GORD.

METHODS

Some 341 patients with GORD were assessed by simultaneous 24-h gastric and oesophageal bilirubin monitoring. Definitions of increased bilirubin exposure were based on the 95th percentiles in healthy volunteers. The relationship between gastric and oesophageal bilirubin exposure and the correlation with disease severity were analysed.

RESULTS

Of the 341 patients with GORD, 130 (38.1 per cent) had increased gastric and 173 (50.7 per cent) had increased oesophageal bilirubin exposure. Of the 173 patients with bile in the oesophagus, 89 (51.4 per cent) had normal and 84 (48.6 per cent) had increased gastric bilirubin exposure. Of these 84 patients, 75 (89 per cent) had oesophagitis or Barrett's oesophagus (P = 0.003). These effects were mainly related to differences in supine reflux.

CONCLUSION

Bile in the oesophagus originates from either normal or increased gastric bilirubin exposure. Patients with increased duodenogastric reflux are more likely to have oesophagitis or Barrett's oesophagus. These findings highlight the role of duodenogastric reflux as an additional factor in the pathogenesis of GORD.

Le reflux biliaire duodéno-gastrique et gastro-œsophagien

This study reviews current data regarding duodenogastric and gastroesophageal bile reflux-pathophysiology, clinical presentation, methods of diagnosis (namely, 24-hour intraluminal bile monitoring) and therapeutic management. Duodenogastric reflux (DGR) consists of retrograde passage of alkaline duodenal contents into the stomach; it may occur due to antroduodenal motility disorder (primary DGR) or may arise following surgical alteration of gastoduodenal anatomy or because of biliary pathology (secondary DGR). Pathologic DGR may generate symptoms of epigastric pain, nausea, and bilious vomiting. In patients with concomitant gastroesophageal reflux, the backwash of duodenal content into the lower esophagus can cause mixed (alkaline and acid) reflux esophagitis, and lead, in turn, to esophageal mucosal damage such as Barrett's metaplasia and adenocarcinoma. The treatment of DGR is difficult, non-specific, and relatively ineffective in controlling symptoms. Proton pump inhibitors decrease the upstream effects of DGR on the esophagus by decreasing the volume of secretions; promotility agents diminish gastric exposure to duodenal secretions by improving gastric emptying. In patients with severe reflux resistant to medical therapy, a duodenal diversion operation such as the duodenal switch procedure may be indicated.

Molecular mechanisms involved in interleukin‐8 production by normal human oesophageal epithelial cells

Summary

Background

Increase in interleukin‐8 in the oesophageal mucosa has been associated with the pathogenesis of reflux oesophagitis.

Aim

To assess the effect of bile acids on the interleukin‐8 expression in normal human oesophageal epithelial cells and to determine its molecular mechanisms.

Methods

Human oesophageal epithelial cells were stimulated with unconjugated bile acids, conjugated bile acids and inflammatory cytokines. Protein and mRNA of interleukin‐8 were measured by enzyme‐linked immunosorbent assay and quantitative real‐time polymerase chain reaction, respectively. In addition, we examined protein kinases and transcription factors involved in interleukin‐8 synthetic pathways using protein kinase inhibitors and luciferase expression vectors, respectively.

Results

Unconjugated bile acids induced interleukin‐8 production from human oesophageal epithelial cells stronger than conjugated bile acids. However, conjugated bile acids in acidic media resulted in remarkable increase of interleukin‐8 production compared with those in neutral‐pH media. Mutation of the binding site of NF‐kB, AP‐1 and NF‐IL6 abrogated the induction of luciferase activities by 100%, 70% and 30%, respectively. Inhibitor of protein kinase A, protein kinase C or p38 mitogen‐activated protein kinase attenuated the production of interleukin‐8 by cholic acid.

Conclusions

These results indicate that bile acids induce interleukin‐8 expression from oesophageal epithelial cells mainly via the activation of NF‐kB as well as AP‐1.

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.

Chenodeoxycholic acid stimulates the progression of human esophageal cancer cells: A possible mechanism of angiogenesis in patients with esophageal cancer

Bile acids are known to promote the growth of gastrointestinal cancer. However, the underlying mechanism remains unclear. We examined whether bile acids induce tumor growth via the cyclooxygenase (COX)-2 angiogenic pathway. In vitro, esophageal squamous cell carcinoma (ESCC) cells and esophageal adenocarcinoma cells were studied. Production of prostaglandin E2 (PGE2) and vascular endothelial growth factor (VEGF) in response to treatment with chenodeoxycholic acid (CDCA) was assessed by enzyme-linked immunosorbent assay (ELISA). COX-2 protein and VEGF protein were measured by immunoblot analysis, and COX-2 activity was measured by ELISA. In vivo, CDCA was administered to ESCC cell-bearing mice. Tumor tissues were analyzed immunohistochemically, and microvessel density was evaluated. Clinically, 134 patients with ESCC who underwent esophagectomy were studied. In vitro, CDCA induced the production of PGE2 and VEGF in dose- and time-dependent manners, and these effects were attenuated by a selective COX-2 inhibitor, mitogen-activated protein kinases inhibitor, or epidermal growth factor receptor inhibitor. CDCA-induced COX-2 in the cell lysate increased the secretion of VEGF into the culture medium. In vivo, CDCA markedly enhanced tumor growth and increased vascularization. Clinically, patients whose tumors expressed both COX-2 and VEGF had poor outcomes. Our results suggest that bile acids, important constituents of duodenal fluid, stimulate the development of human esophageal cancer by promoting angiogenesis via the COX-2 pathway.

Cdx-2 expression in squamous and metaplastic columnar epithelia of the esophagus

The molecular pathogenesis of Barrett's esophagus is poorly understood. Evidence suggests that at a phenotypic level, the metaplastic process begins with the transformation of squamous epithelium in the distal esophagus to cardiac mucosa, which subsequently becomes intestinalized. The homeobox gene Cdx-2 has been shown to be an important transcriptional regulator of embryonic differentiation and maintenance of adult intestinal type epithelium. We hypothesized that Cdx-2 gene expression levels increase with the phenotypic transformation of normal squamous mucosa to the intestinalized columnar mucosa of Barrett's esophagus. Endoscopic biopsies were obtained at the gastroesophageal junction in patients with symptoms of gastroesophageal reflux disease and classified according to histology: normal squamous mucosa (n = 62), cardiac mucosa (n = 19), oxynto-cardiac mucosa (n = 14), and intestinal metaplasia (n = 15). Duodenal biopsies (n = 26) served as the columnar control. After laser capture microdissection and RNA isolation, gene expression levels of Cdx-2 were measured in each tissue type by quantitative reverse transcription polymerase chain reaction. Consistent with its known function, Cdx-2 gene expression levels were highest in duodenal mucosa and nearly absent in squamous epithelium. There was a stepwise increase in Cdx-2 gene expression from cardiac to Barrett's epithelium (P < 0.001). Expression levels of Cdx-2 in cardiac and oxynto-cardiac mucosa were 40-70 times higher and Barrett's mucosa 400 times higher than that found in squamous epithelium. Relative expression of the homeobox gene Cdx-2, known to induce differentiation of intestinal type epithelium, increases in a stepwise fashion during the phenotypic transformation of distal esophageal squamous mucosa to cardiac columnar mucosa and to the intestinalized columnar mucosa of Barrett's esophagus. Therefore, Cdx-2 may be a potential biomarker to detect the early transition to Barrett's esophagus.

Molecular mechanisms involved in interleukin‐8 production by normal human oesophageal epithelial cells

Summary

Background

Increase in interleukin‐8 in the oesophageal mucosa has been associated with the pathogenesis of reflux oesophagitis.

Aim

To assess the effect of bile acids on the interleukin‐8 expression in normal human oesophageal epithelial cells and to determine its molecular mechanisms.

Methods

Human oesophageal epithelial cells were stimulated with unconjugated bile acids, conjugated bile acids and inflammatory cytokines. Protein and mRNA of interleukin‐8 were measured by enzyme‐linked immunosorbent assay and quantitative real‐time polymerase chain reaction, respectively. In addition, we examined protein kinases and transcription factors involved in interleukin‐8 synthetic pathways using protein kinase inhibitors and luciferase expression vectors, respectively.

Results

Unconjugated bile acids induced interleukin‐8 production from human oesophageal epithelial cells stronger than conjugated bile acids. However, conjugated bile acids in acidic media resulted in remarkable increase of interleukin‐8 production compared with those in neutral‐pH media. Mutation of the binding site of NF‐kB, AP‐1 and NF‐IL6 abrogated the induction of luciferase activities by 100%, 70% and 30%, respectively. Inhibitor of protein kinase A, protein kinase C or p38 mitogen‐activated protein kinase attenuated the production of interleukin‐8 by cholic acid.

Conclusions

These results indicate that bile acids induce interleukin‐8 expression from oesophageal epithelial cells mainly via the activation of NF‐kB as well as AP‐1.

Effects of curcumin on reflux esophagitis in rats

The preventive effect of curcumin, a compound isolated from the rhizome of Curcuma longa, on experimental reflux esophagitis in rats was investigated in order to validate its potential therapeutic use for gastroesophageal reflux disease. Curcumin (20 mg/kg, i.d.), the antioxidative agent dimethyl sulfoxide (DMSO) (1 ml/kg, i.p.) or the proton pump inhibitor lansoprazole (1 mg/kg, i.d.) inhibited the formation of acute acid reflux esophagitis by 52.5, 61.5 and 70.9% respectively. Curcumin alone was not effective in preventing chronic acid reflux esophagitis, but the combination of curcumin and DMSO reduced the mortality rate and the severity of the esophagitis ulcer index to the same extent (56.5%) as did the lansoprazole (53.9%). Intraduodenal administration of curcumin also markedly prevented the formation of acute mixed reflux esophagitis, together with reducing the incidence or the severity of neutrophil infiltration, when compared to a control group. In contrast, lansoprazole tended to increase the severity of all histopathological changes, when compared to either the control or the curcumin-treated group. Aminoguanidine, a specific inducible nitric oxide synthase inhibitor, had no preventive effect against both types of acute reflux esophagitis models, and increased the mortality in the chronic acid reflux esophagitis model. From these results, it is indicated that curcumin can effectively prevent acute reflux esophagitis formation. Although curcumin is less potent than lansoprazole in inhibiting acid reflux esophagitis, it is superior to lansoprazole in inhibiting mixed reflux esophagitis. The antiulcerogenic mechanisms are considered to be closely associated with its antioxidant nature and antiinflammatory property.

The impact of reflux composition on mucosal injury and esophageal function

The components of refluxed gastric juice are known to cause mucosal injury, but their effect on esophageal function is less appreciated. Our aim was to determine the effect of acid and/or bile on mucosal injury and esophageal function. From 1993-2004, 402 patients with reflux symptoms had 24-hour pH and Bilitec monitoring, manometry, and endoscopy with biopsies. Mucosal injury (esophagitis or Barrett's esophagus) and esophageal function (lower esophageal sphincter [LES] characteristics and body contractility) in patients with acid reflux, bile reflux, or both were compared with patients without reflux. Reflux was present in 273/402 patients; of these, 37 (13.5%) had increased exposure to bile, 82 (30.0%) had increased exposure to acid, and 154 (56.4%) had increased exposure to both. Mucosal injury was most common with increased mixed acid and bile exposure, followed by acid alone, and was uncommon with bile alone (P < 0.0001). Functional deterioration paralleled mucosal injury (P < 0.0001). Mixed acid and bile exposure was present in more than half of patients with reflux and was associated with the most severe mucosal injury and the greatest deterioration of esophageal function. This suggests that composition of gastric juice is the primary determinant of inflammatory mucosal injury and subsequent loss of esophageal function.

Trypsin activity and bile acid concentrations in the esophagus after distal gastrectomy

The pathogenesis of reflux esophagitis is not well understood and remains controversial. Distal gastrectomy serves as a model to assess the role of duodenal reflux with low gastric acidity in the development of reflux esophagitis. We investigated the relationship between the severity of esophagitis and gastroduodenal juice reflux, with particular focus on trypsin and bile acids after distal gastrectomy reconstructed with Billroth I anastomosis. Twenty-eight patients with gastroesophageal reflux disease after distal gastrectomy were enrolled. Esophageal and duodenal contents were aspirated under endoscopical examination, and their trypsin activity and bile acid concentrations were measured. The grade of reflux esophagitis was assessed by endoscopy and the symptoms were scored. Moreover, the grade of infiltration of inflammatory cells and the expression of COX-2 mRNA in the esophageal epithelium were evaluated. Patients with severe esophagitis had a higher amount of trypsin activity and bile acid concentrations in the esophagus, but not in the duodenum, compared to patients with mild esophagitis (P < 0.05). There was a strong positive correlation between the trypsin activity and the bile acid concentrations in the esophagus (r = 0.743, P = 0.0001). Moreover, the COX-2 mRNA expression and the grade of infiltrating inflammatory cells in the esophageal mucosa significantly correlated with the trypsin activity and bile acid concentrations in the esophagus. Thus, duodenogastroesophageal reflux with low gastric acidity is one of the pathogeneses in the development of reflux esophagitis from the present clinical study with patients after distal gastrectomy reconstructed with Billroth I anastomosis.

Colorectal neoplasia in veterans is associated with Barrett's esophagus but not with proton-pump inhibitor or aspirin/NSAID use

BACKGROUND

It has been suggested that Barrett's esophagus (BE) is associated with an increased risk of developing colorectal neoplasia, but this has not been reported consistently.

AIM

To study whether BE is associated with an increased risk of colorectal neoplasia, and if it is, whether it is dependent on use of proton-pump inhibitors (PPIs) or aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs).

DESIGN

Case-control study.

SETTING

Endoscopic database of the Palo Alto Veterans Affairs Health Care System.

POPULATION

268 veterans with BE were matched with 268 controls without BE.

INTERVENTION

Controls had undergone upper GI endoscopy within 14 days of the corresponding case. Colonoscopy was performed within 6 months in cases and controls.

MAIN OUTCOME MEASURE

Development of colorectal neoplasia.

RESULTS

Colorectal neoplasia was present in 162 of 268 (60%) BE patients and in 105 of 268 (40%) controls (p < 0.001). The presence of BE (odds ratio [OR] 2.02: 95% CI [1.35, 3.04]), but also increasing age (OR 1.24 per decade: 95% CI [1.04, 1.48]) and alcohol use (OR 1.70: 95% CI [1.16, 2.50]) were associated with an increased risk of colorectal neoplasia in multivariable logistic regression analysis, whereas PPIs (OR 0.99: 95% CI [0.66, 1.48]) and aspirin/NSAIDs (OR 0.90: 95% CI [0.61, 1.33]) had no meaningful effect.

LIMITATIONS

This was a retrospective study in mostly male veterans.

CONCLUSIONS

Veterans with BE are at an increased risk of developing colorectal neoplasia. This association is independent from the use of PPIs or aspirin/NSAIDs.

The importance of symptom assessment in the surgical treatment of gastroesophageal reflux disease and Barrett's esophagus

The "art" and science of symptom assessment in the evaluation of patients with gastroesophageal reflux disease has been under emphasized. In fact, it is critical to judgements regarding surgical versus non-surgical therapy and is much more difficult than meets the eye. Many symptoms thought to be secondary to gastroesophageal reflux are not, and some, such as asthma cough and chest pain, which are commonly thought secondary to other causes, are indeed symptoms of reflux. Diagnostic studies are helpful but far from perfect, ultimately requiring the clinician's expert judgement as the key factor in determining a successful outcome. The following outlines both an approach to the assessment of symptoms and when possible, clinical studies shedding light on their cause and interpretation.

Role of cyclooxygenase-2 in the carcinogenesis of gastrointestinal tract cancers: A review and report of personal experience

Selective cyclooxygenase (COX)-2 inhibitors (coxibs) were developed as one of the anti-inflammatory drugs to avoid the various side effects of non-steroidal anti-inflammatory drugs (NSAIDs). However, coxibs also have an ability to inhibit tumor development of various kinds the same way that NSAIDs do. Many experimental studies using cell lines and animal models demonstrated an ability to prevent tumor proliferation of COX-2 inhibitors. After performing a randomized study for polyp chemoprevention study in patients with familial adenomatous polyposis (FAP), which showed that the treatment with celecoxib, one of the coxibs, significantly reduced the number of colorectal polyps in 2000, the U.S. Food and Drug Administration (FDA) immediately approved the clinical use of celecoxib for FAP patients. However, some coxibs were recently reported to increase the risk of serious cardiovascular events including heart attack and stroke. In this article we review a role of COX-2 in carcinogenesis of gastrointestinal tract, such as the esophagus, stomach and colorectum, and also analyze the prospect of coxibs for chemoprevention of gastrointestinal tract tumors.

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.

Role of pancreatic trypsin in chronic esophagitis induced by gastroduodenal reflux in rats

BACKGROUND

Reflux of the duodenal contents with gastric acid has been reported to contribute to the development of esophageal mucosal damage and inflammation. Recent studies show that pancreatic trypsin can stimulate the production of inflammatory mediators, including chemokines and prostaglandins from human esophageal epithelial cells in vitro. The aim of the present study was to investigate the role of pancreatic trypsin in the pathogenesis of chronic esophageal inflammation induced by gastroduodenal reflux in rats.

METHODS

Esophagogastroduodenal anastomosis was carried out in male Wistar rats by anastomosing the jejunum to the gastroesophageal junction under diethyl ether inhalation anesthesia. The animals undergoing surgery were treated with the control diet, rabeprazole sodium, nizatidine, ecabet sodium, camostat mesilate (CMM), ONO-1714, a specific inducible nitric oxide synthase (iNOS) inhibitor, or meloxicam, a selective cyclooxygenase-2 (COX-2) inhibitor. Esophageal injury was evaluated by macroscopic and microscopic findings, and mRNA expression for CINC-1, COX-2, and iNOS was determined by real-time polymerase chain reaction (PCR). Trypsin activity within the esophageal lumen was measured 2 weeks after surgery, and the expression of protease-activated receptor (PAR)-1 and -2 was confirmed by reverse transcription (RT)-PCR.

RESULTS

At 8 weeks after surgery, gastroduodenal reflux induced esophageal erosions and ulcer formation as well as marked thickening of the esophageal wall. Histological study showed an increase of thickness of the esophageal mucosa, hyperplasia of the epidermis and basal cells, ulcer formation, and marked infiltration of inflammatory cells. The macroscopic ulcer score and histological ulcer length were significantly reduced by treatment with rabeprazole or CMM but not by nizatidine or ecabet sodium, compared with each control. Rabeprazole, nizatidine, or ecabet sodium did not affect the severity of mucosal hyperplastic scores or histological parameters in esophagitis. In contrast, the CMM group showed a significant decrease in the mucosal hyperplastic and inflammatory scores. The enhanced expression of CINC-1, COX-2, and iNOS mRNA in the control group was also markedly inhibited in the CMM-treated group. ONO-1714 or meloxicam treatment significantly reduced the macroscopic scores of ulcer and hyperplasia. The trypsin activity in the esophageal lumen was significantly increased in the control diet group, and this increase was significantly inhibited in the CMM-treated group. The expression of PAR-1 and -2 mRNA was confirmed in rat esophageal epithelium.

CONCLUSIONS

With this model, we have demonstrated that CMM significantly reduces inflammation and hyperplasia in the esophageal mucosa. These results indicate that trypsin, which is primarily inhibited by CMM, plays an important role in the mucosal damage induced by gastroduodenal reflux and that it can be a therapeutic target in patients with gastroduodenal reflux esophagitis.

Gastroesophageal and pharyngeal reflux detection using impedance and 24-hour pH monitoring in asymptomatic subjects: defining the normal environment

Airway symptoms are often caused by aspiration of refluxed materials into the larynx. In this study we sought to define the frequency, character, and proximal extent of refluxed contents - including nonacid reflux-in normal subjects using intraluminal impedance to improve our understanding of the relationship between reflux and aspiration. Ten subjects, who had no symptoms of gastroesophageal reflux disease or airway disease, underwent impedance/pH monitoring with a catheter that allowed simultaneous esophageal and pharyngeal monitoring. Impedance detected 496 gastroesophageal reflux episodes in the 10 subjects during 240 hours of study. The majority, 399 (81% of the total) were acid reflux episodes (pH < 4). Ninety-seven were nonacid (pH > 4). Most reflux episodes (348 of 496) reached the mid esophagus (9 cm above lower esophageal sphincter). There were 51 reflux episodes that reached the pharynx (PR). Only 13 (25%) of PR were acidic (pH < 4), while 38 were nonacid. Twenty-six PR episodes were liquid and 25 were mixed (liquid and gas). The median number of PR episodes measured with impedance was 5 (0-10). In asymptomatic subjects, most episodes of gastroesophageal reflux are acidic and reach the midesophagus. Reflux into the PR appears to be more common than previously believed, and most of these episodes are not acidic. Thus, traditional 24-hour pH monitoring may underestimate the presence of pharyngeal reflux. The combination of impedance with pH monitoring markedly enhances our ability to accurately detect potential microaspiration.

Esophageal injury with external esophageal perfusion

BACKGROUND

External esophageal perfusion (EEP) with the idea that esophageal perfusion can be controlled with a single ingredient at a constant rate and concentration, might be used to dissect the injurious role of gastro-duodenal secretions for the progression from esophagitis to Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). This study is to evaluate the EEP rat model for esophagitis induced by using a micro-osmotic pump with bile perfusion.

METHODS

Eighteen adult rats underwent the EEP procedure. Bile (0.5% bovine bile, pH 7.4) was used as perfusion agent and three types of perfusions were performed: 1 week perfusion, 2 weeks perfusion, and 4 weeks perfusion compared to saline perfusion and sham operation. Histological changes, cell proliferation, apoptosis, 8-hydroxy-deoxyguanosine (8-OH-dG) and Manganese superoxide dismutase (MnSOD) were observed after perfusion and compared.

RESULTS

The bile perfusion for 1 week, 2 weeks, and 4 weeks induced mucosa infiltration of inflammatory cells, basal cell hyperproliferation, and papillae hypertrophy in all animals. Histopathology and cellular changes consistent with the findings associated with reflux esophagitis. The apoptotic index, the proliferating index, and expression of 8-OH-dG were significantly increased in the esophageal mucosa compared to controls. MnSOD expression was decreased with bile perfusion compared to saline controls.

CONCLUSIONS

The external esophageal perfusion model enabled precise control of the injurious agent. It induced the typical histological injury and cellular changes seen in severe reflux esophagitis. The cellular changes in apoptosis, proliferation and anti-oxidant defense make this model unique for reflux esophagitis studies. Further studies are needed to induce Barrett's esophagus and esophageal adenocarcinoma.

A prospective study of gastric acid analysis and esophageal acid exposure in patients with gastroesophageal reflux refractory to medical therapy

A number of factors have been proposed to account for the lack of response to medical therapy in patients with gastroesophageal reflux; however, no controlled studies are available in the literature. The goal of this study was to determine possible causes of medical refractoriness in patients with gastroesophageal reflux. Gastric acid output and esophageal acid exposure were measured in patients who continue to have reflux symptoms despite aggressive antisecretory therapy. In addition, an upper endoscopy was also performed in each patient. Patients with a drug-controlled acid output < 1 mEq/hr and a supine total esophageal pH < 4 for less than 1.7% of the time measured were considered responsive to therapy; on the other hand, those with a drug-controlled gastric acid output > 1 mEq/hr and a supine esophageal pH < 4 for more than 1.7% of the time measured were considered resistant to therapy. Twenty-four patients met the inclusion criteria (13 male and 11 female; mean age, 52). Drug-controlled gastric acid output was more than 1 mEq/hr in 25% of patients and less than 1 mEq/hr in the remainder. Of those patients with a gastric acid output of less than 1 mEq/hr (18 patients), 8(44%) had a supine esophageal pH < 4 for more than 1.7% of the time, suggesting that factors other than gastroesophageal reflux likely contributed to their reflux-like symptoms. Acid suppression appears adequate in the majority of patients with gastroesophageal reflux refractory to medical therapy. The exact cause of persistent reflux-like symptoms in patients who fail medical treatment is uncertain but may be related to non-acid-related factors such as esophageal hypersensitivity to physiologic reflux, increased intake of air resulting in aerophagia, or other factors such as bile reflux.

Oral trypsin inhibitor can improve reflux esophagitis after distal gastrectomy concomitant with decreased trypsin activity

BACKGROUND

The pathogenesis of reflux esophagitis is not well understood and remains controversial. Distal gastrectomy serves as a model to assess the role of duodenal reflux with low gastric acidity in the development of reflux esophagitis. We investigated the clinical usefulness and antitrypsin activity after treatment with a trypsin inhibitor, camostat mesilate, against the reflux esophagitis after distal gastrectomy reconstructed with Billroth-I anastomosis.

METHODS

Twenty-eight patients with gastroesophageal reflux disease after distal gastrectomy were prescreened according to esophageal pH level and trypsin activity, and consequently 11 patients were enrolled in the present clinical study. Esophageal and duodenal washings were aspirated for the evaluation of the pretreatment trypsin activity. Then 100 mg of camostat mesilate was administered orally. At 30 and 120 minutes after the administration, duodenal washings were aspirated for the evaluation of posttreatment trypsin activity. Thereafter, 300 mg of camostat mesilate was administered orally 3 times daily for a 4-week period. On the 28th day of administration, the grade of reflux esophagitis (Los Angeles classification) was re-evaluated under endoscopy and the esophageal washings were aspirated for the evaluation of trypsin activity.

RESULTS

The trypsin activities in the duodenum both at 30 and 120 minutes after oral ingestion of camostat mesilate were decreased significantly in comparison with those in the pretreatment period in each patient (P<.001). In 6 of 7 patients with detectable trypsin activity in the esophagus, the activities after the 28th day of treatment were lower than those in the pretreatment period, and the symptoms were milder than those before treatment (P<.05). Furthermore, endoscopic evaluation showed that 40% of patients were grade B, C, and D after treatment (28th day), whereas 70% of patients were grade B, C, and D before the treatment.

CONCLUSIONS

Oral administration of trypsin inhibitor can improve reflux esophagitis after distal gastrectomy concomitant with decreased trypsin activity.

Bile reflux in the constellation of gastroesophageal reflux disease

Gastric acid and bile acids are a particularly noxious combination when they interact with the mucosa of the upper intestinal tract. There is a critical pH range, between 3 and 6, in which bile acids exist in their soluble, un-ionized form, can penetrate cell membranes, and accumulate within mucosal cells. At a lower pH, bile acids are precipitated, and at a higher pH, bile acids exist in their noninjurious ionized form. Experimental, clinical, and immunohistochemical studies show that acid and bile reflux are increased in patients who suffer from GERD, are the key factor in the pathogenesis of Barrett's esophagus, and possibly are related to the development of esophageal adenocarcinoma.

Gastroesophageal reflux and cancer

The causal relationship between GERD and esophageal adenocarcinoma, although unclear just a few decades ago, now is established fairly well. The physiologic changes and the biocellular alterations of the damaged esophageal mucosa are documented better. Despite this knowledge, the dramatic increase in the incidence of esophageal cancer cannot be explained. The absolute risk of esophageal adenocarcinoma arising from GERD is low, and, at present, does not justify population-screening programs. Still, with the notion that adenocarcinoma of the esophagus is an aggressive cancer once documented, important questions still are in need of answers for patients suffering from reflux symptoms. Patients who have reflux disease are not necessarily symptomatic. It remains unclear if patients experiencing reflux symptoms should undergo mandatory endoscopy with biopsies at the esophagogastric junction. Furthermore, metaplasia of the lower esophagus often is not readily recognizable at endoscopy, and only biopsies can document abnormal histology. A severe and prolonged history of reflux always should orient to the possibility of a reflux-related columnar-lined esophagus. Once documented, Barrett's esophagus needs to be seen as a premalignant condition not necessarily leading to adenocarcinoma formation; despite their increased risk of tumor formation, most patients who have Barrett's esophagus die of other causes. During regular endoscopic follow-up, multilevel circumferential biopsies should document the evolution of the histologic changes in the lower esophagus and at the gastroesophageal junction of these patients. It is the only method available to document the appearance of dysplasia. It still is unclear if medicine or surgery provides the best quality of life and the best protection against the development of dysplasia and the possible progression toward adenocarcinoma formation when intestinal metaplasia is present in the esophagus.

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

Gastro-oesophageal reflux disease is defined as the presence of symptoms or lesions that can be attributed to the reflux of gastric contents into the oesophagus. Aspiration and prolonged monitoring studies in humans have shown that reflux of gastric contents is comprised of both acid and non-acid components, in healthy as well as diseased people. Methods to monitor the non-acid component of the refluxate are described in detail. Experimental models 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 a 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 disease 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 and surgery, are discussed.

Fundoplication and the risk of esophageal cancer in gastroesophageal reflux disease: a Veterans Affairs cohort study

BACKGROUND AND AIMS

It has been proposed that fundoplication can reduce the risk of esophageal cancer in patients with gastroesophageal reflux disease (GERD). In this cohort study, we assessed the effect of fundoplication on the incidence of esophageal cancer.

METHODS

We identified all Veterans Affairs (VA) patients with GERD who had fundoplication between 1986 and 1990 and matched (1-2) to controls with GERD and no fundoplication and to controls with no GERD. We calculated incidence rates for esophageal cancer through October 2002 and examined the effect of fundoplication on the risk of esophageal cancer using Kaplan-Meier survival analysis and Cox proportional hazard analysis. We calculated and adjusted for the propensity score for receiving fundoplication.

RESULTS

We identified 946 patients who had fundoplication, 1,892 patients who had GERD without fundoplication, and 5,676 patients with no GERD. The mean age was 55 yr and 97.5% were men in all three groups. During a follow-up of 11,156 patient-years (PY), there were eight cases of esophageal cancer (72/100,000) in the fundoplication group. During a follow-up of 20,115 PY, there were eight cases of esophageal cancer (40/100,000) in the GERD without fundoplication group. During a follow-up of 59,439 PY, no patients in the group with no GERD developed esophageal cancer. The Kaplan-Meier analysis showed no significant difference in cumulative esophageal cancer rates between the fundoplication group and the GERD no-fundoplication group. The adjusted hazard ratio of esophageal cancer with fundoplication was 1.88 (95% CI: 0.70-5.03).

CONCLUSIONS

GERD is a risk factor for esophageal cancer, but there is insufficient evidence that fundoplication reduces that risk.

Acid and duodenogastroesophageal reflux after esophagectomy with gastric tube reconstruction

OBJECTIVE

Patients who undergo esophagectomy with gastric tube reconstruction incur increased risk for acid reflux and duodenogastroesophageal reflux. Few postesophagectomy studies of gastroesophageal reflux disease have included simultaneous 24-h pH and bilirubin monitoring. The aim of this study is to evaluate acid reflux and duodenogastroesophageal reflux after esophagectomy with gastric tube reconstruction.

METHODS

Reflux symptom evaluation, endoscopy, and simultaneous 24-h pH and bilirubin monitoring in the cervical esophagus were performed in 25 patients who underwent Ivor Lewis esophagectomy, intrathoracic esophagogastrostomy, and digital dilation of the pyloric ring as treatment for esophageal cancer.

RESULTS

Reflux symptoms were severe, mild, and absent in 2, 7, and 16 patients, respectively. Reflux esophagitis and Barrett's esophagus was observed in 11 and 1 patients, respectively. Elevated acid reflux occurred in 7 patients (28%). Elevated duodenogastroesophageal reflux was recorded in 11 patients (44%). Reflux profile analysis identified three patterns: 4 subjects (16%) with both elevated acid reflux and duodenogastroesophageal reflux; 3 (12%) with only elevated acid reflux; and 7 (28%) with only elevated duodenogastroesophageal reflux. Of 7 patients with only elevated duodenogastroesophageal reflux, 4 developed reflux esophagitis. Although reflux symptoms did not correlate with endoscopic esophagitis, a significant correlation was observed between endoscopic esophagitis and acid reflux and/or duodenogastroesophageal reflux.

CONCLUSIONS

Reflux symptoms represented a poor indication of esophagitis in patients with esophagectomy and gastric tube reconstruction. Simultaneous 24-h pH and bilirubin monitoring can help in identifying patients at high risk for reflux esophagitis, as well as indicating the cause of esophagitis.

Normalization of oesophageal pH does not guarantee control of duodenogastro-oesophageal reflux in Barrett's oesophagus

BACKGROUND

Proton-pump inhibitors are effective at preventing the acid component of gastro-oesophageal refluxate from entering the oesophagus. It is not clear whether proton-pump inhibitors prevent duodenogastro-oesophageal reflux.

AIM

To measure oesophageal exposure to duodenogastro-oesophageal refluxate while on proton-pump inhibitors in patients with Barrett's oesophagus.

METHODS

Twenty-five patients (23 male) with Barrett's oesophagus underwent 24 h oesophageal pH and Bilitec 2000 monitoring while on omeprazole 40 mg/day (n = 19) or omeprazole 60 mg/day (n = 6). All patients were undergoing argon plasma ablation of their Barrett's epithelium as part of a clinical trial and the Bilitec measurements were only carried out after the ablation had been completed.

RESULTS

20 of 25 (80%) patients had a normal oesophageal pH profile. Fifteen of the 25 (60%) had abnormal oesophageal exposure to bile as measured by Bilitec 2000. Of the 20 patients who had a normal 24 h oesophageal pH profile, 11 (55%) had pathological exposure to bile in their oesophagus.

CONCLUSION

Complete acid suppression does not guarantee elimination of duodenogastro-oesophageal reflux.

Mechanisms underlying duodeno-gastric reflux in man

BACKGROUND

Recent studies suggest that duodeno-gastro-oesophageal reflux (DGER) contributes to the occurrence of reflux oesophagitis and Barrett's oesophagus. The mechanisms underlying duodeno-gastric reflux (DGR), a prerequisite for DGER, are poorly understood.

AIMS

To study the occurrence of DGR in relation to interdigestive and postprandial gastroduodenal motility.

SUBJECTS AND METHODS

Ten healthy subjects underwent stationary gastroduodenal manometry with simultaneous duodenal and antral Bilitec recording 4 h before and 5 h after ingestion of a liquid meal. Eight volunteers underwent the same study, with administration of erythromycin postprandially.

RESULTS

During the interdigestive phase II, all volunteers had short DGR episodes. Postprandially, DGR occurred in all subjects, on average 39 +/- 28 min after the start of the meal, and was cleared from the stomach after 242 +/- 23 min. Induction of increased antral motility and of a premature phase III, by administration of erythromycin, was associated with faster gastric DGR clearance. However, there was no direct temporal relationship between erythromycin-induced gastric phase III and erythromycin-induced DGR clearance.

CONCLUSION

In healthy subjects, duodenogastric reflux occurs sporadically in the interdigestive state and is a normal phenomenon in the postprandial period. Erythromycin induces faster clearance of DGR from the stomach, which depends on enhanced antral contractile activity rather than premature phase III.

Effect of "white diet" during bile monitoring with Bilitec 2000 on esophageal pH-metry in patients with gastroesophageal reflux disease

With introduction of the Bilitec 2000 device, intraluminal bile monitoring has become a standard technique for evaluation of patients with gastroesophageal reflux disease and symptoms of bile reflux. A specific "white diet" excluding colored food is necessary to provide correct measurements. The influence of this specific diet on simultaneous esophageal pH monitoring is unknown. Forty patients with reflux symptoms were studied prospectively. Meal times and supine and erect phases of measurement were recorded in a standardized fashion using a patient protocol. Esophageal 24-hour pH monitoring with administration of a "colorless" diet (water, milk, potatoes, fish, chicken) was started on day 1, followed by esophageal 24-hour pH-metry with intake of a normal diet on day 2. Data from the two successive pH measurements were compared. The prevalence of a pathologic esophageal pH-metry was significantly higher during intake of a normal diet compared with a colorless diet (P=0.025). During total and upright phases, administration of a white diet led to significant reduction in the percentage of time with a pH less than 4 (P </= 0.01), the total number of reflux episodes (P </= 0.001), and the DeMeester's score (P=0.01). This difference was exclusively found in patients with a normal pH-metry (group 1, n=13) and pathologic upright reflux (group 2, n=12). No change in reflux pattern was found in patients with isolated supine reflux (group 3, n=7) and combined upright and supine reflux (group 4, n=8). In patients with a pathologic upright reflux pattern, administration of a white diet results in a significant modification of esophageal pH-metry. Data derived from simultaneous esophageal pH and bile monitoring should be interpreted with care.

The mutagenic potential of duodenoesophageal reflux

SUMMARY BACKGROUND DATA

Duodenogastric-esophageal reflux disease is directly linked to Barrett's esophagus and to the development of esophageal adenocarcinoma. Despite this link, little is known about the mutagenic potential of refluxed material on the esophageal mucosa. We hypothesize that the reflux of gastric and duodenal content causes mutations in esophageal mucosa in vivo.

METHODS

Seven Sprague Dawley/Big Blue F1 lacI transgenic rats underwent esophagoduodenostomy (ED) to surgically create duodeno-gastric-esophageal reflux. Fourteen nonoperated rats served as negative (n = 7) and as positive (n = 7/methyl-N-amyl-nitrosamine [MNAN] intraperitoneally) controls. The animals were killed 16 weeks after operation or injection, the entire esophageal mucosa was harvested, and mutation frequency was determined through standard Big Blue Mutagenesis Assay.

RESULTS

Gross esophagitis was evident in all operated animals. The frequency of lacI mutations in esophageal mucosal cells of animals with ED was significantly higher, nearly 1.5-fold, than that of nonoperated animals. Nitrosamine administration resulted in a nearly 20-fold increase of lacI mutation frequency. Thirteen mutations were successfully sequenced, 46% occurred at CpG dinucleotide sites and 61% were either C to T or G to A transitions.

CONCLUSIONS

The data provide preliminary evidence of the mutagenic potential of bile reflux on esophageal epithelium. The specific mutations are markedly higher than would be expected by chance and are similar to that found in p53 mutations of human esophageal adenocarcinoma, providing a link to human esophageal cancer.

Expression of Cdx2 in early GRCL of Barrett's esophagus induced in rats by duodenal reflux

The intestine-specific caudal-related homeobox transcription factor Cdx2 is widely accepted to play a key role in intestinal development and differentiation in mammals. We studied the role of Cdx2 in the development of Barrett's esophagus (BE). In previous studies, we have shown a sequence of morphological changes of squamous epithelium leading to BE, found a peculiar metaplastic change common to other parts of gut, and proposed the concept of a "gut regenerative cell lineage" (GRCL). The GRCL is characterized by pyloric-foveolar metaplasia with goblet cell metaplasia, which occurs in the regenerative process in response to chronic inflammation. BE very likely develops through the GRCL, and we studied the expression of Cdx2 in various lesions of rat esophageal mucosa induced by duodenal reflux, using reverse transciptase-polymerase chain reaction and immunohistochemistry against Cdx2. We found that Cdx2 was expressed not only in specialized columnar epithelium (SCE) of BE, but also in several pyloric gland and foveolar metaplastic cells which developed in the basal layer of the squamous epithelium at an earlier stage of SCE development. These findings indicate that Cdx2 plays a crucial role in directing intestinal-type differentiation of the GRCL.

How to make a Barrett esophagus: pathophysiology of columnar metaplasia of the esophagus

Barrett esophagus is defined as a specialized intestinal replacing the squamous epithelium of the esophageal mucosa in response to gastroesophageal reflux. Barrett metaplasia is a healing process that develops to protect the esophagus from further damage. Although mechanisms by which Barrett metaplasia evolves toward dysplasia and adenocarcinoma have been extensively studied, the process by which squamous epithelium is replaced by specialized intestinal metaplasia is poorly understood. Barrett esophagus develops when defense mechanisms in the esophageal mucosa (luminal secretion of mucus, bicarbonate, growth factors, etc.) are overwhelmed by an ongoing cycle of mucosal injury and repair. Hydrogen ion, pepsin, trypsin, and bile acids are considered harmful agents that synergistically invade the esophageal mucosa. Areas of destroyed squamous epithelium are then progressively reepithelized by a columnar epithelium that may originate from multipotent stem cells located within the basal layer of the normal esophageal mucosa or in the ducts of submucosal glands.

Barrett's esophagus in females: a comparative analysis of risk factors in females and males

OBJECTIVES

Gastroesophageal reflux symptoms occur with similar frequency in males and females, yet Barrett's esophagus is less common in females. The reason for this disparity is unknown. The aim of this study was to determine the factors related to Barrett's in females.

METHODS

The records of 796 patients (462 male, 334 female) evaluated from 1990 to 2000 for symptoms of reflux were retrospectively reviewed. Physiologic abnormalities based on results of endoscopic, motility, pH, and Bilitec testing were identified, and factors related to the presence of Barrett's were determined using univariate and multivariate analysis.

RESULTS

Females with reflux symptoms were significantly less likely to have a positive 24-h pH test, a defective lower esophageal sphincter, or a hiatal hernia than males with reflux symptoms. Further, females with reflux on the basis of an abnormal 24-h pH test had significantly less esophageal acid exposure than males with reflux. In contrast, esophageal exposure to refluxed acid and bilirubin was similar in females (n = 50) and males (n = 136) with Barrett's. On multivariable analysis increased esophageal bilirubin exposure was the only significant factor associated with the presence of Barrett's in male and female patients with reflux disease.

CONCLUSIONS

Females with reflux symptoms have less esophageal acid exposure on average than males. However, females and males with Barrett's have a similar severity of reflux, and the female gender does not protect against the development of Barrett's in the setting of advanced reflux disease. Esophageal bilirubin exposure is the major risk factor for the presence of Barrett's in patients with reflux disease.

Expression of inducible nitric oxide synthase is increased in rat Barrett's esophagus induced by duodenal contents reflux

Barrett's esophagus is a premalignant condition of esophageal adenocarcinoma. Inducible nitric oxide synthase (iNOS) is induced by cytokines and can generate locally high concentrations of nitric oxide (NO), whose metabolites can mediate genotoxicity and influence multistage carcinogenesis by causing DNA damage. Therefore, we evaluated the immunolocalization and expression of iNOS in surgically induced rat Barrett's esophagus. Esophagoduodenal anastomosis was performed in rats for inducing reflux of duodenal contents. Rats were killed at postoperative 10, 20, 30 and 40 weeks. We examined histologic changes and iNOS expression in esophagus by immunohistochemistry and reverse transcription-polymerase chain reaction. Eighty six percent of experimental rats showed Barrett's esophagus above esophagoduodenal junction. iNOS immunoreactivity was clearly observed in the epithelial cells of Barrett's esophagus, predominantly at the apical surface of epithelial cells. Cytoplasmic staining was also seen only in atypical Barrett's esophagus. iNOS mRNA was detected only in the lower esophagus of experimental group. In conclusion, this study suggests that iNOS has some roles on Barrett's esophagus formation.