Role of acid and duodenogastroesophageal reflux in gastroesophageal reflux disease

BACKGROUND & AIMS

Acid and pepsin are known to cause esophagitis. However, the role of duodenogastroesophageal reflux (DGER) in producing esophageal mucosal injury across the spectrum of gastroesophageal reflux disease (GERD) is controversial.

METHODS

Twenty controls (13 men; mean age, 41 years), 30 patients with GERD (15 men; mean age, 41 years), and 20 patients with Barrett's esophagus (17 men; mean age, 58 years) were studied. Twenty-four-hour ambulatory acid and bilirubin measurements were obtained with Bilitec 2000 using a glass pH electrode and fiberoptic sensor.

RESULTS

Percentage times pH was < 4, bilirubin level was > or = 0.14, and fasting gastric bile acid concentrations showed a graded increase across the GERD spectrum. Esophageal exposure to both acid and DGER was the most prevalent reflux pattern (100% in patients with complicated and 89% in patients with uncomplicated Barrett's esophagus, 79% in patients with esophagitis, and 50% in patients without esophagitis). The majority (70%-91%) of DGER episodes occurred in an acidic environment (pH < 4). Linear regression analysis found a significant correlation (r = 0.73; P < 0.01) between percentage time pH was < 4 and percentage time bilirubin absorbance level was > or = 0.14.

CONCLUSIONS

Both acid and DGER show a graded increase in severity across the GERD spectrum. Acid and DGER occur simultaneously in the majority of the reflux episodes.

Duodenogastroesophageal reflux: relationship to pH and importance in Barrett's esophagus

BACKGROUND/AIMS

Several reports suggest that duodenogastroesophageal reflux may produce esophagitis, Barrett's esophagus, and esophageal adenocarcinoma. The purpose of this study was to understand better the relationship of pH (< 4 and > 7), duodenogastroesophageal reflux, and fasting bile acid concentrations in producing esophageal damage.

METHODS

Using a spectrophotometric technique to measure bile reflux, four groups were studied: healthy subjects, reflux patients, patients with Barrett's esophagus, and patients with esophageal symptoms after partial gastrectomy.

RESULTS

Simultaneous 24-hour pH and bile monitoring of distal esophagus found close association between total percent of time pH < 4 and duodenogastroesophageal reflux (r = 0.78; P < 0.001) but a poor relationship (r = -0.06) with total percent of time pH > 7, suggesting that the term alkaline reflux is a misnomer. Duodenogastroesophageal reflux increased significantly with the severity of reflux disease, being greatest in patients with Barrett's esophagus and comparable with that in patients with partial gastrectomy. Fasting bile acid concentrations did not distinguish patients with Barrett's esophagus from those with reflux. Rather, increased quantity of acid reflux was the single factor most characterizing patients with Barrett's esophagus. Omeprazole (20 mg twice daily) normalized acid reflux parameters (13.8% +/- 1.6% to 0.8% +/- 0.6%) and significantly (P < 0.001) decreased duodenogastroesophageal reflux (32.8% +/- 6.9% to 4.7% +/- 1.7%).

CONCLUSIONS

Acid reflux is the primary factor in the development of Barrett's esophagus. Bile reflux parallels acid reflux and, at best, may have a synergistic role. Aggressive acid suppression with omeprazole markedly decreases both.

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

OBJECTIVE

The author's goal was to determine the role of duodenal components in the development of complications of gastroesophageal reflux disease.

SUMMARY AND BACKGROUND DATA

There is a disturbing increase in the prevalence of complications, specifically the development of Barrett's esophagus among patients with gastroesophageal reflux disease. Earlier studies using pH monitoring and aspiration techniques have shown that increased esophageal exposure to fluid with a pH above 7, that is, of potential duodenal origin, may be an important factor in this phenomenon.

METHODS

The presence of duodenal content in the esophagus was studied in 53 patients with gastroesophageal reflux disease confirmed by 24-hour pH monitoring. A portable spectrophotometer (Bilitec 2000, Synectics, Inc.) with a fiberoptic probe was used to measure intraluminal bilirubin as a marker for duodenal juice in the esophagus. Normal values for bilirubin monitoring were established for 25 healthy subjects. In a subgroup of 22 patients, a custom-made program was used to correlate simultaneous pH and bilirubin absorbance readings.

RESULTS

Fifty-eight percent of patients were found to have increased esophageal exposure to gastric and duodenal juices. The degree of mucosal damage increased when duodenal juice was refluxed into the esophagus, in that patients with Barrett's metaplasia (n = 27) had a significantly higher prevalence of abnormal esophageal bilirubin exposure than did those with erosive esophagitis (n = 10) or with no injury (n = 16). They also had a greater esophageal bilirubin exposure compared with patients without Barrett's changes, with or without esophagitis. The correlation of pH and bilirubin monitoring showed that the majority (87%) of esophageal bilirubin exposure occurred when the pH of the esophagus was between 4 and 7.

CONCLUSIONS

Reflux of duodenal juice in gastroesophageal reflux disease is more common than pH studies alone would suggest. The combined reflux of gastric and duodenal juices causes severe esophageal mucosal damage. The vast majority of duodenal reflux occurs at a pH range of 4 to 7, at which bile acids, the major component of duodenal juice, are capable of damaging the esophageal mucosa.

Complications of gastroesophageal reflux disease. Role of the lower esophageal sphincter, esophageal acid and acid/alkaline exposure, and duodenogastric reflux

The factors contributing to the development of esophageal mucosal injury in gastroesophageal reflux disease (GERD) are unclear. The lower esophageal sphincter, esophageal acid and acid/alkaline exposure, and the presence of excessive duodenogastric reflux (DGR) was evaluated in 205 consecutive patients with GERD and various degrees of mucosal injury (no mucosal injury, n = 92; esophagitis, n = 66; stricture, n = 19; Barrett's esophagus, n = 28). Manometry and 24-hour esophageal pH monitoring showed that the prevalence and severity of esophageal mucosal injury was higher in patients with a mechanically defective lower esophageal sphincter (p less than 0.01) or increased esophageal acid/alkaline exposure (p less than 0.01) as compared with those with a normal sphincter or only increased esophageal acid exposure. Complications of GERD were particularly frequent and severe in patients who had a combination of a defective sphincter and increased esophageal acid/alkaline exposure (p less than 0.01). Combined esophageal and gastric pH monitoring showed that esophageal alkaline exposure was increased only in GERD patients with DGR (p less than 0.05) and that DGR was more frequent in GERD patients with a stricture or Barrett's esophagus. A mechanically defective lower esophageal sphincter and reflux of acid gastric juice contaminated with duodenal contents therefore appear to be the most important determinants for the development of mucosal injury in GERD. This explains why some patients fail medical therapy and supports the surgical reconstruction of the defective sphincter as the most effective therapy.

Role of acid and duodenogastric reflux in esophageal mucosal injury: a review of animal and human studies

The role of acid and duodenogastric reflux (DGR) in the development of esophageal mucosal injury has been extensively investigated using both animal and human models. In this report, clinical and experimental data are reviewed. The mechanisms by which gastric and duodenal contents produce esophageal mucosal injury are also discussed. Acid and pepsin are unquestionably important in causing mucosal damage at low pH values in both animal and human models. Animal models suggest synergistic damaging potential for conjugated bile acids and HCI as well as that of unconjugated bile acids and trypsin in more neutral pH values. Human evidence for the involvement of bile and its constituents has been controversial; however, the advent of better technology to detect DGR is beginning to clarify the role of these constituents. The contribution of each methodology in clarifying the extent of involvement of DGR in esophageal mucosal injury is reviewed. Despite some conflicting results, preliminary human studies support the results from the animal data suggesting synergistic damaging effects for both bile and acid in esophageal mucosal injury. The implication of these studies in treating gastroesophageal reflux disease are discussed.

Reflux of duodenal or gastro-duodenal contents induces esophageal carcinoma in rats

Esophageal adenocarcinoma arises from Barrett's esophagus, which is induced by gastro-esophageal reflux. This refluxate often contains duodenal contents, whose backflow triggers gastric carcinoma, suggesting the hypothesis that refluxed duodenal contents cause esophageal carcinoma. This study examines the role of duodenal and gastric reflux in the absence of exogenous carcinogens in esophageal carcinogenesis. Wistar male rats, 120 in all, each weighing approximately 250 g, were used. Three experimental procedures were performed to produce gastro-duodeno-esophageal reflux, duodeno-esophageal reflux and gastro-esophageal reflux, for comparison with 2 control procedures, Roux-en-Y reconstruction and a sham operation. The animals were fed a standard diet and were examined 50 weeks after surgery. While no carcinoma was found among the 16 gastro-esophageal-reflux, 11 Roux-en-Y and 12 sham-operation animals, 10 of the 12 animals with gastro-duodeno-esophageal reflux (83%) and 10 of the 13 with duodeno-esophageal reflux (77%) developed esophageal carcinoma. The difference between groups was significant (p < 0.001). Two animals with gastro-duodeno-esophageal reflux had esophageal double and triple carcinomas respectively. Of the 23 carcinomas, 16 were adenocarcinoma, 4 adenosquamous carcinoma, and 3 squamous-cell carcinoma. Adenocarcinoma developed from the columnar-lined epithelium near the esophago-jejunostoma, while adenosquamous and squamous-cell carcinoma arose from the squamous esophagitis. These observations demonstrate that refluxed duodenal contents per so are responsible for esophageal carcinogenesis.

Gastroduodenal dysfunction and bacterial colonisation of the ventilated lung

The source of ventilator-associated pneumonia (gastric or oropharyngeal flora) remains controversial. We investigated the source of bacterial colonisation of the ventilated lung in 100 consecutive intensive-care patients. Gram-negative bacilli were isolated from the lower respiratory tract in 19 patients. Bacteria isolated from the stomach contents either previously or at the same time were identical to lower respiratory isolates in 11 patients. No gram-negative oropharyngeal isolate was identical to a lower respiratory tract isolate. Gastric bacterial overgrowth with gram-negative bacilli was associated with the presence of bilirubin in the stomach contents. Detectable bilirubin was also associated with subsequent acquisition of gram-negative bacilli in the lower respiratory tract. Only 5 gastric aspirate specimens with pH < 3.5 contained gram-negative bacilli. These results establish a relation between duodenal reflux and subsequent bacterial colonisation of the lower respiratory tract. Restoration of normal gastroduodenal motility might help prevent pneumonia in intensive-care patients.

Implication of duodenogastric reflux in the pathogenesis of Barrett's oesophagus

Fasting and postprandial intragastric bile acid concentrations have been estimated and compared in patients with complications of Barrett's oesophagus, patients with Barrett's oesophagus without complications, patients with oesophagitis and a group of normal subjects who acted as controls. There was no significant difference in fasting intragastric bile acid concentrations between the groups. Postprandial bile acid concentrations were significantly greater in the patients with complications of Barrett's than in the remaining groups at 60, 90 and 120 min. Significant concentrations of bile acids were seen in gastric juice of unaltered pH and may be undetected on intra-oesophageal pH monitoring. Duodenogastric reflux may be implicated in the pathogenesis of complications of Barrett's oesophagus.

Duodenal reflux induces cyclooxygenase-2 in the esophageal mucosa of rats: evidence for involvement of bile acids

BACKGROUND & AIMS

Reflux of duodenal contents including bile acids is believed to contribute to esophageal injury and Barrett's esophagus. Cyclooxygenase (COX)-2, an inducible form of COX, has been implicated in both inflammation and carcinogenesis. In this study, we investigated the effects of bile acids and duodenal reflux on COX-2 expression in cultured esophageal cells and tissue, respectively.

METHODS

Immunoblotting and Northern blotting were used to assess the effects of bile acids on COX-2 expression in esophageal cell lines. Immunoblotting and immunohistochemistry were performed to evaluate the effects of duodenal reflux on COX-2 expression and cell proliferation in esophageal tissue.

RESULTS

Unconjugated bile acids were about fivefold more potent inducers of COX-2 messenger RNA, COX-2 protein, and prostaglandin synthesis than conjugated bile acids. Acidifying the culture medium sensitized esophageal cells to bile acid-mediated induction of COX-2. The induction of COX-2 by bile acids was mediated by phosphatidylinositol-3 kinase and extracellular signal-regulated kinase 1/2 mitogen-activated protein kinases. In experimental animals, duodenoesophageal reflux led to esophagitis, marked thickening of the esophageal mucosa, and enhanced expression of COX-2. Increased immunoreactivity for Ki-67 and cyclin D1 indicated that enhanced cell proliferation contributed to mucosal thickening.

CONCLUSIONS

Reflux of duodenal contents into the esophagus led to increased COX-2 expression and mucosal thickening. Bile acids are likely to contribute to these effects.

Duodenoesophageal reflux induces esophageal adenocarcinoma without exogenous carcinogen

In the rat model, esophageal adenocarcinoma reproducibly develops following surgically induced duodenal reflux into the esophagus and administration of nitrosamine. In addition, decreasing gastric acid via partial or total gastrectomy increases the prevalence of adenocarcinoma in this model. We questioned whether carcinogen was necessary for cancer development in the gastrectomized model and whether esophageal acidification could reverse the effect of gastrectomy. Three groups of 26 rats each were randomized to a surgical procedure to produce one of the following reflux models: gastroduodenal reflux by esophagojejunostomy, duodenal reflux by total gastrectomy and esophagojejunostomy, or no reflux by Roux-en-Y reconstruction. In a second experiment, 42 rats were operated on to induce duodenal reflux. One week following surgery, they were randomized to receive acidified water (pH 1.8) or tap water. The animals were killed at 24 weeks of age, and the esophagus was evaluated histologically. All animals with reflux had severe esophagitis and 87% developed columnar lining of the distal esophagus. Nearly half (48%) developed adenocarcinoma at the anastomotic site 16 weeks postoperatively and without carcinogen administration. Cancer prevalence did not differ between animals with gastroduodenal or duodenal reflux but tended to be lower in animals receiving acidified water. Duodenoesophageal reflux is carcinogenic in the rat model. Exogenous carcinogen is not necessary for cancer development in gastrectomized rats.

The role of acid and alkaline reflux in laryngeal squamous cell carcinoma

HYPOTHESIS

At present, main factors considered responsible for the onset of squamous cell carcinoma are tobacco smoking, alcohol abuse, and exposure to viral and toxic agents. In last years, great interest has been focused on gastroesophageal reflux as independent carcinogenic factor and co-carcinogen in association with smoking and alcohol assumption.

STUDY DESIGN

Initially, the aim of this study was to objectively evaluate the presence of distal and proximal esophageal reflux with multielectrode pH measurement in patients with cancer of the larynx and/or hypopharynx (group A). However, in the course of the study, pharyngolaryngeal cancer was also observed in 4 patients with achlorhydria; therefore, the hypothesis that alkaline reflux might be involved in the onset of laryngeal cancer was tested (group B).

METHODS

Twenty-one consecutive patients with laryngeal or hypopharyngolaryngeal squamous cell carcinoma (group A) entered the study. Twenty-one patients without laryngo-pharyngeal diseases were used as control subjects. A validated questionnaire of the clinical history was completed by all patients who underwent 24-hour pH monitoring. Group B included 40 consecutive gastrectomized patients (28 males and 12 females) in whom biliary or alkaline reflux was directly consequent to Billroth I or Billroth II operation. The control group was composed of 40 non-gastrectomized dyspeptic patients. The clinical history was controlled and obtained; EDGS and ENT examination with videolaryngoscopy was performed in all patients.

RESULTS

In group A, pH measurement showed pathological reflux in 80.9% (17 of 21) of patients with no typical symptoms in 63.7% of them. The difference was significant with respect to the control group. In group B, 6 of 40 (15%) had preneoplastic lesions or a history of laryngeal tumor. The difference was significant with respect to the control group. A total of 7.5% of group B patients had previously undergone CO2 laser cordectomy for laryngeal squamous cell carcinoma and 7.5% had leukoplakia. We found a significantly higher incidence (<.05) of neoplastic and preneoplastic disease of the larynx in patients undergoing Billroth II and total gastrectomy than in those undergoing Billroth I and Roux-en-Y resection. We also found a significant increase (<.01) in ENT lesions in the group of patients who had undergone gastrectomy more than 20 years previously.

CONCLUSIONS

In agreement with literature reports, results obtained in group A confirmed that gastroesophageal reflux is often present in patients with neoplastic lesions of the pharynx and larynx. Furthermore, gastric resection is indicated for the first time as an additional risk factor or cofactor of precancerosis and squamous cell carcinoma of the pharynx or larynx. Further studies are necessary to establish the cause and effect relationship between biliary reflux and pharyngo-laryngeal tumors.

Influence of pancreatic and biliary reflux on the development of esophageal carcinoma

We previously presented an experimental model of Barrett's adenocarcinoma of the esophagus by demonstrating that esophagojejunostomy combined with subcutaneous injection of 2,6-dimethylnitrosomorpholine in Sprague-Dawley rats resulted in development of adenocarcinoma in the distal esophagus. The present study was devised to investigate the influence of pancreatic and biliary duodenal-content reflux on the induction of esophageal carcinoma. Three groups of 8-week-old Sprague-Dawley rats were controls: the first was exposed to pancreatic reflux, the second to biliary reflux, and the third to both. The other three experimental groups were similar except that a 1/100 LD50 dose of 2,6-dimethylnitrosomorpholine was injected subcutaneously weekly, starting on day 15. Carcinoma of the esophagus was induced only in animals receiving the carcinogen after exposure to either pancreatic reflux (3/22, 13%) or pancreatic and biliary reflux (9/27, 33%). Half of the carcinomas were adenocarcinoma and half were squamous cell carcinoma. These findings suggest that under these experimental conditions, in which the carcinogen is used in a low dose, esophageal carcinoma is induced only when pancreatic secretions are present in the duodenal-content reflux. Biliary reflux, however, appears to exert a cocarcinogenic effect when combined with pancreatic secretions. The clinical relevance of these findings needs further evaluation. Conceivably, the elimination of pancreatic and biliary duodenal-content reflux in patients with documented Barrett's mucosa may inhibit the progression from metaplasia to adenocarcinoma.

Effect of gastroduodenal juice and dietary fat on the development of Barrett's esophagus and esophageal neoplasia: an experimental rat model

BACKGROUND

Reflux of duodenal content into the lower esophagus of rats enhances the formation of nitrosamine-induced esophageal cancer and results in the induction of adenocarcinoma. We investigated the extent of the mucosal injury that was produced when the lower esophagus of rats was exposed to the reflux of gastroduodenal juice in the presence or absence of a carcinogen and tested the hypothesis that induction of esophageal cancer in this model would be influenced by the intake of dietary fat.

METHODS

Esophagoduodenostomy with gastric preservation was performed in 165 Sprague-Dawley rats in order to expose the lower esophagus to the reflux of gastroduodenal juice. Postoperatively selected groups of rats were treated with the carcinogen methyl-n-amylnitrosamine (MNAN). Subsequently, rats were fed diets of differing fat and calorie content for 20 weeks until they were put to death.

RESULTS

Refluxed gastroduodenal juice, in the absence of MNAN, induced esophageal inflammatory changes (diffuse papillomatosis and hyperkeratosis) in 38 of 39 rats (97%), specialized columnar metaplasia (Barrett's esophagus) in four of 39 (10%), dysplasia in three of 39 (8%), and squamous cell carcinoma in one of 39 (3%). Diet did not influence the incidence of neoplasia in the absence of MNAN treatment. In rats treated with MNAN, refluxed gastroduodenal juice induced inflammation in 110 of 111 rats (99%), columnar metaplasia in 14 of 111 (13%), and cancer in 63 of 111 (57%). Fifty-eight percent of esophageal tumors were squamous cell carcinoma and 42% were adenocarcinoma. The highest incidence of tumors was observed in rats fed the semipurified high-fat diet (24 of 29; 83%) compared with rats fed the semipurified control diet (13 of 29; 45%), semipurified, calorie-restricted diet (15 of 27; 55%), and chow diet (11 of 26; 42%), p < 0.05.

CONCLUSIONS

Reflux of gastroduodenal content into the lower esophagus of rats can induce both Barrett's metaplasia and neoplasia. Addition of a carcinogen increases the tumor yield and results in a proportion of the lesions being adenocarcinoma. This carcinogenic process is promoted by a diet with a high fat content.

The role of acid and duodenal gastroesophageal reflux in symptomatic GERD

OBJECTIVE

Mixed reflux of acid and duodenal contents frequently occurs in patients with gastroesophageal reflux disease (GERD). The aim of this study was to establish the contribution of acid and duodenal gastroesophageal reflux (DGER) to symptoms in patients with presumed GERD.

METHODS

A total of 72 patients (37 women), mean age 45 yr (+/-2 yr), underwent 24-h ambulatory pH and Bilitec monitoring. Patients pressed a marker button when experiencing typical symptoms. For each symptom episode, minimal pH and maximal bilirubin optical density in a 2- or 4-min interval were calculated. For each patient, the symptom index (SI) and symptom-association probability for acid and for bile reflux were determined.

RESULTS

A total of 544 symptom episodes were identified. Using a 2-min interval, 28% were associated with acid reflux, 9% with DGER, and 12% with mixed reflux. No significant difference was found when a 4-min interval was used. A positive SI for acid reflux was present in 21% of the patients and for DGER in 14%. All patients with a positive SI for DGER had also a positive SI for acid reflux. A positive symptom-association probability for acid reflux was present in 22% of the patients, for DGER in 7% of the patients, and for mixed reflux in 10% of the patients.

CONCLUSIONS

Symptom episodes in patients with presumed GERD are more related to acid reflux than to DGER. DGER does not play a major role in producing typical esophageal symptoms.

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.

Impact of the biliary diversion procedure on carcinogenesis in Barrett's esophagus surgically induced by duodenoesophageal reflux in rats

OBJECTIVE

To determine whether the elimination of bile reflux in the established esophagojejunostomy model of Barrett's esophagus (BE) will reduce or eliminate the risk of developing esophageal adenocarcinoma.

SUMMARY BACKGROUND DATA

Reflux of duodenal juice as well as gastric acid plays an important role in the pathogenesis of BE and adenocarcinoma. Duodenoesophageal reflux (DER) per se induces these diseases without carcinogen. However, it is unclear whether antireflux surgery induces regression of BE and prevents adenocarcinoma.

METHODS

Two hundred F344 male rats underwent one of following 3 operations: (1) total gastrectomy and esophagojejunostomy to induce DER, followed by killing after 20 (n = 13), 30 (n = 12), and 50 weeks (n = 30); (2) biliary diversion procedure, converted to Roux-en-Y method, to avoid bile regurgitation into the esophagus at 20 (n = 29) and 30 weeks (n = 32) after the operation to induce DER, followed by killing 50 weeks after initial operation; or (3) total gastrectomy and Roux-en-Y esophagojejunostomy followed by killing after 50 weeks served as controls (n = 28).

RESULTS

BE developed in more than half of the animals exposed to DER for 20 weeks, in more than 90% of rats with DER for 30 weeks, and in 100% of animals exposed to DER for 50 weeks. In the incidence and the length of BE, there is no difference between the animals that underwent biliary diversion at 20 (62%) and 30 weeks (94%) and those that had DER for 20 (54%) and 30 weeks (92%), respectively. Incidence of adenocarcinoma was significantly lower in the rats that underwent the biliary diversion procedure after 30 (19%) and 20 weeks (3%) than in the rats that had DER for 50 weeks (60%) (P < 0.005). None of the control animals that underwent Roux-en-Y esophagojejunostomy developed BE and carcinoma.

CONCLUSIONS

It is likely that the converting procedure from the esophagojejunostomy to induce DER to biliary diversion does not lead to regression of BE but prevents the development of esophageal adenocarcinoma in the rats.

Thioproline inhibits development of esophageal adenocarcinoma induced by gastroduodenal reflux in rats

Several epidemiological cohort studies have suggested that duodeno-gastroesophageal reflux per se induces Barrett's esophagus leading to increased risk of the development of esophageal adenocarcinoma (EAC). However, the exact causative factors behind EAC remain unclear. Recently, we designed a new duodenal contents reflux model which retained normal stomach function. In this model, duodenal contents flowed back into the esophagus and stomach resulting in repeated re-entry into the esophagus through the site of esophagojejunostomy. To elucidate the factors underlying the development of EAC, thiazolidine-4-carboxylic acid (thioproline, TPRO) was applied to the new reflux models as a nitrite scavenger and as a probe to detect reactive nitrogen species (RNS). Post-operatively, 31 animals were divided into two groups according to diet. Animals belonging to the control group were given normal diet (n = 18), while the TPRO group was given food containing 0.5% TPRO (n = 13). All esophageal sections in both groups were examined using hematoxylin and eosin staining and immunohistochemical analysis of inducible nitric oxide synthase (iNOS). EACs developed in 7 of 18 rats (38.9%) of the control group, whereas no EACs were detected in the TPRO group (Fisher's exact test, P < 0.05). Conversely, esophageal squamous cell carcinoma (ESCC) was detected in 1 of 18 rats (5.6%) of the control group and in 1 of 13 rats (7.7%) of the TPRO group. The incidence of ESCC was not significantly different between the two groups (P = 0.671). iNOS protein was overexpressed in Barrett's esophagus of both groups. The present results suggest that RNS such as nitric oxide and peroxynitrite and nitroso compounds derived from reflux of duodenal contents play an important role in the development of EAC, and that the primary causes of ESCC and EAC may differ.

Duodenogastric reflux and foregut carcinogenesis

Epidemiologic cohort studies have established that after distal gastric resection, there is a higher risk of gastric carcinoma. It is likely that a main factor of this higher risk is the excessive duodenogastric reflux induced by surgery, because the incidence of stump carcinomas is higher in Billroth II than in Billroth I, and most of the stump carcinomas are located near the stoma. In addition, several groups of investigators have suggested that duodenogastric reflux per se induces stump carcinomas in rats. There is another human duodenogastric reflux, the primary duodenogastric reflux, through the pylorus. Experiments in animals have demonstrated that this type of duodenal reflux also induces gastric carcinomas in the antrum of the stomach that has not undergone surgery. Recent clinical attention has focused on the role of duodenogastric reflux in the pathogenesis of Barrett's esophagus and subsequent esophageal adenocarcinomas. Experimentally, reflux of duodenal contents into the esophagus can cause not only Barrett's esophagus and subsequent adenocarcinomas, but also squamous cell carcinomas. These findings suggest that duodenogastric reflux may be implicated in gastric and esophageal, that is, foregut carcinogenesis.

Duodenal reflux through the pylorus induces gastric adenocarcinoma in the rat

We investigated whether duodenal reflux through the pylorus is involved in the development of gastric cancer. Male Wistar rats weighing 230-250 g were subjected to three types of operative procedures: (i) allowing reflux through the pylorus; (ii) allowing reflux through a gastrojejunal stoma; and (iii) gastrotomy. No carcinogens were given, and the animals were killed 50 weeks after surgery. No cancers were detected in any of the 18 animals with gastrotomy. In contrast, seven (41%) of 17 animals with reflux through the pylorus and four (31%) of 13 animals with reflux through the stoma had adenocarcinoma. Differences in the incidence between both reflux groups and the gastrotomy group were significant (P < 0.01 and P < 0.05 respectively). All of the adenocarcinomas developed in the pyloric mucosa near the pylorus in the animals with reflux through the pylorus, and in the oxyntic mucosa near the stoma in those with reflux through the stoma. Adenocarcinomas appeared as a polyploid mass with or without slight central erosion. Most of the adenocarcinomas were of the well-differentiated tubular type, and the others were of the mucinous type. No differences in either the histologic type or depth of invasion of the adenocarcinoma were recognized between the two duodenogastric reflux groups. Precancerous or paracancerous lesions, such as adenoma, adenocystic proliferation, and stomal pseudopyloric metaplasia, were more frequently found in the same region as the adenocarcinomas. These findings suggest that duodenogastric reflux in the rat has potent carcinogenic activities not only in the oxyntic mucosa through the stoma, but also in the pyloric mucosa through the pylorus.

Duodenogastric reflux potentiates the injurious effects of gastroesophageal reflux

Experimental studies have shown that the severity of esophageal mucosal injury in gastroesophageal reflux disease is related to the reflux of both gastric and duodenal juice. The purpose of this study was to determine whether duodenal juice potentiates esophageal injury in patients with reflux disease or, in fact, causes no harm allowing acid and pepsin to do the damage. A total of 148 consecutive patients who had no previous gastric or esophageal surgery underwent endoscopy and biopsy, manometry, and 24-hour esophageal pH and bilirubin monitoring. Esophageal injury was defined by the presence of erosive esophagitis, stricture, or biopsy-proved Barrett's esophagus. Exposure to duodenal juice, identified by the absorbance of bilirubin, was defined as an exposure time exceeding the ninety-fifth percentile measured in 35 volunteers. To separate the effects of gastric and duodenal juice, patients were stratified according to their acid exposure time. One hundred patients had documented acid reflux on pH monitoring, and in 63 of them it was combined with reflux of duodenal juice. Patients with combined reflux (50 of 63) were more likely to have injury than patients without combined reflux (22 of 37; P < 0.05). When the acid exposure time was greater than 10%, patients with injury (n = 40) had a greater exposure to duodenal juice (median exposure time 17.2% vs. 1.1%, P = 0.006) than patients without injury (n = 5), but there was no difference in their acid exposure (16.9% vs. 13.4%). Patients with dysplasia of Barrett's epithelium (n = 9) had a greater exposure to duodenal juice (median exposure time 30.2% vs. 7.2%, P = 0.04) compared to patients without complications (n = 25), whereas acid exposure was the same (16.4% vs. 15%). Duodenal juice adds a noxious component to the refluxed gastric juice and potentiates the injurious effects of gastric juice on the esophageal mucosa.

Contribution of acid and duodenogastro-oesophageal reflux to oesophageal mucosal injury and symptoms in partial gastrectomy patients [see comment]

BACKGROUND

The role of acid and pepsin in causing symptoms and oesophagitis is well established; however, the significance of duodenogastro-oesophageal reflux (DGOR) in this disorder is unclear.

AIMS

To understand the role of acid and DGOR in causing upper gastrointestinal (GI) symptoms and oesophageal mucosal injury in partial gastrectomy (PG) patients.

METHODS

Thirty two PG patients with upper GI symptoms were studied. Twenty four hour ambulatory acid and bilirubin measurements were obtained with Bilitec 2000 using glass electrode and fibreoptic sensor. Upper GI symptoms and oesophagitis were correlated with either acid or DGOR.

RESULTS

The PG patients were a heterogeneous group: 28% (9/32) had mixed reflux (acid+/DGOR+); 50% (16/32) had only DGOR (acid-/DGOR+); and 22% (7/32) had neither (acid-/DGOR-). Upper GI symptoms were associated with both mixed reflux (69%) and DGOR (24%). Six patients (67%) in the acid+/DGOR+ group had oesophagitis; no acid-/DGOR+ or acid-/DGOR- patients had oesophagitis. Mixed reflux showed a significant (p < 0.0001) association with oesophagitis, while DGOR did not (p = 0.3).

CONCLUSIONS

(1) The majority of upper GI symptoms and all cases of oesophagitis in the PG patients occurred in patients who had mixed refluxate (acid and DGOR); (2) DGOR without simultaneous acid reflux may cause symptoms, but was not associated with oesophagitis in this patient group.

Duodenogastric reflux in rat gastric carcinoma

This study investigated the role of long-term reflux of bile and/or pancreaticoduodenal secretions in the genesis of gastric carcinoma in the rat. Adenocarcinoma, dysplasia and adenocystic proliferation were found only in those animals with reflux of pancreaticoduodenal secretions alone or in combination with bile. No such changes were found in control animals with no reflux or animals with bile reflux alone. The differences in incidence of adenocarcinoma were significant. The presence of adenocarcinoma was not related to the pH of the intragastric contents or to the bacterial flora. This suggests that duodenogastric reflux is implicated in gastric carcinogenesis in the rat and that pancreaticoduodenal secretions rather than bile are responsible.

Duodenogastric reflux in patients with Barrett's esophagus

The role of duodenogastric reflux in the pathogenesis of gastroesophageal reflux disease is not clear. Using hepatobiliary scanning techniques, we found evidence of duodenogastric reflux in six of 13 patients with Barrett's esophagus. This compares with only two positive studies in 19 control subjects. This difference is statistically significant (P = 0.038, two-tailed Fisher's exact test). Three of nine patients who had gastroesophageal reflux without Barrett's esophagus had evidence of duodenogastric reflux, a frequency not significantly different from either of the other groups. Gastroesophageal reflux of bile and pancreatic enzymes, in addition to gastric acid may contribute to the greater esophageal damage often seen in Barrett's esophagus. The presence of duodenogastric reflux in these patients may have important pathophysiologic and therapeutic implications.

Expression of cyclooxygenase 2, microsomal prostaglandin E synthase 1, and EP receptors is increased in rat oesophageal squamous cell dysplasia and Barrett's metaplasia induced by duodenal contents reflux

BACKGROUND AND AIM

It is known that bile acids can induce mucosal injury, stimulate cell proliferation, and promote tumorigenesis. A large body of genetic and biochemical evidence indicate that the biosynthetic pathway of prostaglandin E2 (PGE2) may play an important role in human and rodent tumours. Therefore, we examined the expression pattern of cyclooxygenase 1 (COX-1), COX-2, and microsomal prostaglandin E synthase 1 (mPGES-1), as well as EP receptor subtypes in rat oesophageal lesions induced by duodenal contents reflux.

METHODS

Oesophagoduodenal anastomosis was performed in rats to induce duodenal contents reflux. We examined histological changes and expression of COX-1, COX-2, mPGES-1, and EP receptor subtypes in the oesophagus by immunohistochemistry and reverse transcription-polymerase chain reaction.

RESULTS

Normal control oesophageal tissues showed COX-1 expression in subepithelial stromal cells, including endothelial cells and muscular cells, and did not reveal expression of COX-2 or mPGES-1. In the case of squamous cell lesions, immunoreactivity of COX-1 was similar to that of normal lesions, and COX-2 was maximally expressed around the vascular papillae of tissues showing dysplasia and surrounding epithelial layer and basal layer. mPGES-1 was highly expressed in stromal cells with COX-2 expression. In the case of Barrett's oesophagus, COX-2 and mPGES-1 were predominantly in subepithelial stromal cells. mRNA levels of COX-2, mPGES-1, EP2, EP3, and EP4 were higher in the experimental groups than in controls.

CONCLUSIONS

We suggest that the biosynthetic pathway of PGE2 may play an important role in oesophageal squamous cell dysplasia and glandular metaplasia induced by duodenal contents reflux.

Induction of oesophageal and forestomach carcinomas in rats by reflux of duodenal contents

A study was designed to determine whether oesophageal carcinomas can be induced through reflux of duodenal contents. Male Wistar rats weighing 230-250 g were divided into three groups according to the surgical procedure performed: (1) the duodenal contents were directed into the forestomach through a stoma (duodeno-forestomach reflux); (2) the duodenal contents were regurgitated into the forestomach through the glandular stomach (duodeno-glandular-forestomach reflux); and (3) a sham operation was performed as a control. Animals were fed standard CRF-1 solid food and tap water that was not exposed to carcinogens and were sacrificed 50 weeks post-operatively. While no neoplasia was observed in any of the 32 control rats, 4/11 (36%) with duodeno-forestomach reflux and 3/18 (17%) animals with duodeno-glandular-forestomach reflux developed carcinomas in the lower oesophagus and forestomach. The incidence in each group was significantly higher than in the controls (P < 0.01 and P < 0.05 respectively). Six of the seven lesions consisted of squamous cell carcinomas, and one was a mucinous adenocarcinoma. Oesophageal columnar epithelial metaplasia was observed in two (18%) of the animals with duodeno-forestomach reflux. Carcinomas were always surrounded by chronic inflammatory changes, including regenerative thickening, basal cell hyperplasia and dysplasia. Additional well-differentiated adenocarcinomas were observed in the prepyloric antrum of 6/18 (33%) animals with duodeno-glandular-forestomach reflux. These findings indicate that chronic reflux of duodenal contents may cause oesophageal carcinoma.