Gastric secretion of acid and pepsin in patients with esophageal stricture and appropriate controls

Mathematical model of the relationship between pH holding time and erosive esophagitis healing rates

Effective suppression of gastric acid secretion promotes healing of erosive esophagitis. Treatment guidelines recommend proton pump inhibitors (PPIs) and histamine H2-receptor antagonists (H2RAs). Emerging evidence also supports potassium-competitive acid blockers (P-CABs). The aim was to construct a mathematical model to examine the relationship between pH holding time ratios (HTRs) and erosive esophagitis healing rates with H2RAs, PPIs and P-CABs. By literature search, we identified studies of H2RAs, PPIs or P-CABs that reported mean pH >4 HTRs at steady state (days 5-8) and erosive esophagitis healing rates after 4 and/or 8 weeks. We aggregated treatments by drug class and developed a non-linear, mixed-effects model to explore the relationship between pH >4 HTRs and healing rates. The pH dataset included 82 studies (4297 participants; 201 dosage arms); healing rate data came from 103 studies (43,417 patients; 196 treatment arms). P-CABs achieved the longest periods with intragastric pH >4, and the highest healing rates after 4 and 8 weeks. The predicted probabilities of achieving ≥90% healing rates at 8 weeks were 74.1% for P-CABs, 17.3% for PPIs and 0% for H2RAs. P-CABs provide the longest duration with intragastric pH >4 and, accordingly, the highest healing rates of erosive esophagitis.

Reflux esophagitis, functional and non-functional

The pathogenesis of gastroesophageal reflux disease has been explained by acid-peptic model. However, related with the progress of the diagnostic modalities, another phenotypical group of patients were defined and called "functional disorders of the esophagus". These patients are important because diagnosis is particularly difficult, co-morbid disorders especially psychiatric diseases are common, proton pump inhibitor response is low, and surgical results are very poor. Simpler and translational science studies are required in functional groups in order to differentiate from acid-peptic disorders. New and more accurate diagnostic modalities as well as therapeutic approaches are strongly needed in this particularly new and exciting era, especially in the effect of neuromodulators. Current diagnostic modalities should also be evaluated and in fact, normal values should be established. New medications, especially acting at the level of esophageal epithelium and intercellular spaces, might shift the paradigm.

An unusual presentation of zollinger-ellison syndrome

Zollinger-Ellison syndrome is an often progressive, persistent and frequently life-threatening disease, described for the first time as characterized by ulceration of the upper jejunum, hypersecretion of gastric acid and non-beta islet cell tumors of the pancreas; this syndrome is due to the hypersecretion of gastrin. We report a case of Zollinger-Ellison syndrome presenting as severe esophagitis evolving in stenosis, which demonstrates how a delayed diagnosis may induce risk of disease spreading. In this setting new diagnostic approaches, such as somatostatin receptor scanning and positron emission tomography with 68 Ga-labeled octreotide, could be particularly useful, as well as further new therapeutic options, such as molecular targeted treatments and peptide receptor radionuclide therapy, though surgery is currently the only form of curative treatment, and the role of the therapeutic options mentioned needs to be clarified by forthcoming studies.

Bile salts disrupt human esophageal squamous epithelial barrier function by modulating tight junction proteins

Reflux of acid and bile acids contributes to epithelial tissue injury in gastro-esophageal reflux disease. However, the influence of refluxed material on human esophageal stratified epithelial barrier function and tight junction (TJ) proteins has not been fully elucidated. Here, we investigated the influence of acid and bile acids on barrier function and TJ protein distribution using a newly developed air-liquid interface (ALI) in vitro culture model of stratified squamous epithelium based on primary human esophageal epithelial cells (HEECs). Under ALI conditions, HEECs formed distinct epithelial layers on Transwell inserts after 7 days of culture. The epithelial layers formed TJ, and the presence of claudin-1, claudin-4, and occludin were detected by immunofluorescent staining. The NP-40-insoluble fraction of these TJ proteins was significantly higher by day 7 of ALI culture. Exposure of HEECs to pH 2, and taurocholic acid (TCA) and glycocholic acid (GCA) at pH 3, but not pH 4, for 1 h decreased transepithelial electrical resistance (TEER) and increased paracellular permeability. Exposure of cell layers to GCA (pH 3) and TCA (pH 3) for 1 h also markedly reduced the insoluble fractions of claudin-1 and -4. We found that deoxycholic acid (pH 7.4 or 6, 1 h) and pepsin (pH 3, 24 h) significantly decreased TEER and increased permeability. Based on these findings, ALI-cultured HEECs represent a new in vitro model of human esophageal stratified epithelium and are suitable for studying esophageal epithelial barrier functions. Using this model, we demonstrated that acid, bile acids, and pepsin disrupt squamous epithelial barrier function partly by modulating TJ proteins. These results provide new insights into understanding the role of TJ proteins in esophagitis.

The histological and immunohistochemical aspects of bile reflux in patients with gastroesophageal reflux disease

Introduction. The pathogenesis of GERD is strongly related with mixed acid and bile reflux. Benign and malignant esophageal and gastric lesions have been associated with synergetic activity between those parameters. Bile reflux causes reactive gastropathy evaluated with Bile Reflux Index (BRI). The aim was to investigate if the sequence: bile reflux-intestinal metaplasia-GERD-esophagitis, is associated with apoptotic/oncogenetic disturbances. Materials/Methods. Fifteen asymptomatic subjects and 53 GERD patients underwent gastroscopy with biopsies. The specimens examined histologically and immunohistochemically for p53, Ki-67, Bax, and Bcl-2. Results. Elevated BRI score detected in 47% (25/53) of patients with GERD and in 13% (2/15) of controls (P = 0.02). Severe esophageal lesions were significantly more common in BRI (+) patients (14/25) compared to BRI (-) ones (P = 0.0049). Immunohistochemical analysis did not show associations between BRI score and biomarker expression. Conclusions. Bile reflux gastropathy is associated with GERD severity, but not with oncogene expression or apoptotic discrepancies of the upper GI mucosa.

The role of proton pump inhibitors in the treatment of Zollinger-Ellison syndrome

Zollinger-Ellison syndrome is characterised by refractory peptic ulcer disease, diarrhoea and gastric acid hypersecretion associated with a gastrin-secreting tumour. The incidence is unknown, but, in the US, the frequency is 0.1-3.0 million people. Zollinger-Ellison syndrome is associated with multiple endocrine neoplasia type 1 in 25-35% of the cases. The diagnosis of Zollinger-Ellison syndrome is suggested when plasma gastrin is > 1000 pg/ml and the basal acid output is > 15 mEq/h or when associated with a pH < 2. The treatment is focused on controlling gastric acid hypersecretion and localisation of the tumour and its metastases. Proton pump inhibitors are the most effective antisecretory drugs and can be administered at high dosages. This review focuses on the role of the proton pump inhibitors in the management of gastric acid hypersecretion in Zollinger-Ellison syndrome.

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

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

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

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

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

Review article: trials on reflux disease -- the role of acid secretion and inhibition

The importance of gastric acid in the pathophysiology of gastro-oesophageal reflux disease is substantiated by the extraordinary therapeutic success of acid inhibition in the management of the disease. The influence of many risk factors for gastro-oesophageal reflux disease is also mediated through their effect on gastric acid secretion and acid reflux. Helicobacter pylori reduces the risk of gastro-oesophageal reflux disease by causing corpus gastritis and reducing gastric acid output. The geographical and temporal trends of H. pylori infection in human populations and its influence on gastric acid secretion are responsible for much of the apparent epidemiology of gastro-oesophageal reflux disease. On average, intra-oesophageal exposure to acid is higher in patients who respond poorly to antisecretory medication. It also tends to increase with increasing severity of reflux disease. However, gastric acid secretion and intra-oesophageal acid exposure vary markedly in reflux patients. The degrees of gastric or intra-oesophageal acidity do not allow the prediction of the presence or severity of gastro-oesophageal reflux disease in the individual subject. The many clinical trials on gastro-oesophageal reflux disease indicate that the reflux of gastric acid constitutes an essential mechanism in the development of this disease, but that additional and partly unknown risk factors must contribute to its aetiology and promote its occurrence in the individual patient.

Risk factors for esophagitis in extreme acid hypersecretors with and without Zollinger-Ellison syndrome

BACKGROUND & AIMS

Whereas severe duodenal ulcer is the hallmark of acid hypersecretion in Zollinger-Ellison syndrome (ZE) and similar states, the esophagus also is at high risk. We quantified the incidence of esophagitis and various risk factors that might contribute to it.

METHODS

Sixty-eight acid hypersecretors (basal acid output >15 mmol/h), 50 patients with ZE, and 18 patients without ZE with normal gastrin levels were studied by gastric analysis, serum gastrin levels, and endoscopy. In 44 of 68 patients, esophageal manometry was performed after the esophagus had healed.

RESULTS

Erosive esophagitis, grade 2 or worse, was found in 65%; an additional 15% had heartburn only, for a total reflux disease incidence of 80%. ZE accounted for 95% of severe esophagitis. Patients with and without esophagitis had the same high overnight fasting gastric residual volume and acidity, as well as basal and peak acid and pepsin outputs. However, patients with esophagitis had a lower median lower esophageal sphincter pressure (LESP) of 15.5 vs. 23 mm Hg in those without symptoms; the critical discriminator threshold was 16 mm Hg. Multivariate analysis further identified frequent vomiting and obesity as positive predictors of esophagitis, whereas Helicobacter pylori was a strong negative predictor (odds ratio, 0.16), possibly related to an elevated LESP in patients infected with H. pylori.

CONCLUSIONS

Erosive esophagitis is very common in acid hypersecretors. Identified risk factors that could promote abnormal esophageal exposure to the high acid and pepsin levels in our population of hypersecretors were vomiting, LESP < 16 mm Hg, and obesity, whereas H. pylori appeared to protect the esophagus not by reduced acid, but through an elevated LESP.

Meal-stimulated gastric acid secretion and integrated gastric acidity in gastro-oesophageal reflux disease

BACKGROUND

No current methods exist to determine meal-stimulated gastric acid secretion in humans under conditions that approximate those of daily living with the ingestion of breakfast, lunch and dinner.

METHODS

Gastric and oesophageal pH were measured in 26 healthy subjects and in 59 subjects with gastro-oesophageal reflux disease. Meal-stimulated gastric acid secretion was calculated from the buffer capacity of the meals determined in vitro and from the time required for the gastric pH to decrease to pH 2 in vivo following ingestion of the meal.

RESULTS

There was a significant correlation between gastric secretion with each meal and the corresponding post-prandial integrated gastric acidity. There was also a significant correlation between meal-stimulated gastric secretion and integrated gastric acidity from 09.00 to 22.00 h in both subjects with gastro-oesophageal reflux disease and controls. In subjects with gastro-oesophageal reflux disease, gastric secretion and integrated gastric acidity from 09.00 to 22.00 h were significantly higher than those in controls. There was a significant correlation between oesophageal acidity and integrated gastric acidity from 09.00 to 22.00 h in subjects with gastro-oesophageal reflux disease.

CONCLUSIONS

As post-prandial gastric acidity is increased in subjects with gastro-oesophageal reflux disease, it seems likely that increased gastric acidity is an important aetiological factor in this disease.

Cisapride inhibits meal-stimulated gastric acid secretion and post-prandial gastric acidity in subjects with gastro-oesophageal reflux disease

BACKGROUND AND AIMS

KCNQ1 potassium channels in human gastric parietal cells are thought to be involved in gastric acid secretion. As cisapride can inhibit similar channels in other tissues and is an effective treatment for nocturnal heartburn, we examined the effects of cisapride on gastric and oesophageal acidity, gastric emptying and heartburn severity in subjects with gastro-oesophageal reflux disease.

METHODS

Subjects (n = 11) had suffered from heartburn four times or more per week for at least 6 months. Gastric pH and oesophageal pH were measured before, during and after a standard meal ingested over 15 min. Each subject received placebo or 10 mg cisapride orally, 30 min before the beginning of the meal. Meal-stimulated gastric acid secretion was calculated from the amount of HCl required to titrate the homogenized standard meal to pH 2 in vitro and the time required for the pH of the ingested meal to decrease to pH 2 in vivo. Heartburn severity was assessed at 15-min intervals beginning at the end of the meal. Gastric emptying of solids was measured using a [(13)C]-octanoic acid breath test.

RESULTS

Cisapride significantly decreased meal-stimulated gastric acid secretion by 20%, decreased integrated gastric and oesophageal acidity by 50-60% and transiently increased the expiration of (13)CO(2). Cisapride did not significantly alter heartburn severity.

CONCLUSIONS

The cisapride-induced decreases in meal-stimulated gastric acid secretion, gastric acidity and oesophageal acidity in subjects with gastro-oesophageal reflux disease can account for its beneficial clinical effects. These results also raise the possibility that gastric KCNQ1 potassium channels are important in meal-stimulated gastric acid secretion and possibly in the pathophysiology of gastro-oesophageal reflux disease.

Helicobacter pylori infection in children

A number of scientific breakthroughs since H pylori first became recognized as a human pathogen have increased our understanding of the pathogenesis of gastroduodenal disease. In particular, advances in molecular bacteriology and the complete sequencing of the H pylori genome in 1999, and soon thereafter the human genome, provide tools allowing better delineation of the pathogenesis of disease. These molecular tools for both bacteria and host should now be applied to multicenter pediatric studies that evaluate disease outcome. More recent developments indicate that a better understanding of the microbial-host interaction is critical to furthering knowledge with respect to H pylori-induced diseases. Studies are needed to evaluate either DNA-based or more traditional protein-based vaccines, to evaluate more specific antimicrobials that confer minimal resistance, and to evaluate probiotics for the management of H pylori infection. Multicenter multinational studies of H pylori infection in the pediatric population, which include specific, randomized controlled eradication trials, are essential to extend current knowledge and develop better predictors of disease outcome.

Synergy between low-dose ranitidine and antacid in decreasing gastric and oesophageal acidity and relieving meal-induced heartburn

BACKGROUND

The pathophysiology of recurrent postprandial heartburn and the basis for the effectiveness of antacids or low doses of histamine H2-receptor antagonists have not been well studied.

METHODS

The selected subjects (n=26) had heartburn more than four times a week for at least 2 months, which was responsive to antacids. Gastric pH and oesophageal pH were measured for 1 h before, during, and 4.5 h after ingestion of a meal over 0.5 h. Heartburn severity was assessed at 15-min intervals beginning at the end of the meal. Each subject randomly received placebo, 75 mg ranitidine, 420 mg calcium carbonate, and ranitidine plus calcium carbonate. Values for pH were converted to acid concentration (mM) and integrated acidity was calculated from the cumulative, time-weighted means of the acid concentrations for every second of the postprandial recording period.

RESULTS

There was a close temporal relationship between heartburn and oesophageal acidity. Most oesophageal acid exposure occurred over a 90-min period that began approximately 45 min after the end of the meal. During this period the gastric acid concentration was less than 5% of maximal. Ranitidine significantly decreased gastric but not oesophageal acidity, whilst antacid significantly decreased oesophageal but not gastric acidity. Ranitidine plus antacid significantly decreased both gastric and oesophageal acidity. Antacid alone and ranitidine plus antacid significantly decreased heartburn severity.

CONCLUSIONS

Determining integrated gastric and oesophageal acidity provides novel information regarding the pathophysiology of meal-induced heartburn as well as the actions of low-dose ranitidine and antacid. For subjects with meal-induced heartburn, treatment with low-dose ranitidine plus antacid is particularly effective in decreasing gastric and oesophageal acidity as well as heartburn severity.

Integrated acidity and the pathophysiology of gastroesophageal reflux disease

OBJECTIVES

The aim of this study was to demonstrate that integrated esophageal and gastric acidity values, calculated from 24-h pH recordings, can provide more precise quantitative temporal data than the conventional pH parameters historically associated with gastroesophageal reflux disease (GERD) investigations.

METHODS

Esophagogastroduodenoscopy results and pH tracings from 20 GERD subjects with > or =10% esophageal acid contact time were studied. Integrated gastric and esophageal acidity were calculated from time-weighted average hydrogen ion concentrations at each second of the 24-h recording period.

RESULTS

Integrated esophageal acidity correlated with grade of esophagitis. Two quite distinct GERD subtypes were identified, with either a monophasic or biphasic pattern of integrated esophageal acidity. "Biphasic" subjects differed from "monophasic" subjects in terms of magnitude and pattern of integrated esophageal acidity. Although both groups had significant integrated nocturnal gastric acidity, only the biphasic GERD subjects had concomitant increases in nocturnal integrated esophageal acidity. Esophagitis grade was correlated with magnitude rather than pattern of integrated esophageal acidity, and it was possible to calculate a reflux coefficient that seems to provide an estimate of the quantitative motor disturbance present in GERD.

CONCLUSIONS

Integrated esophageal and gastric acidity provide quantitative measures of GERD pathophysiology and, compared to conventional pH parameters, should enhance evaluation of therapeutic interventions.

Peptic strictures of the esophagus

Peptic esophageal strictures occur in the context of inadequately treated gastroesophageal reflux, especially in elderly patients. Studies show more pronounced abnormalities of esophageal function resulting in an increased number of prolonged reflux episodes. The diagnosis is best made by a combination of barium esophagram and endoscopy. Patients usually require esophageal dilation to relieve dysphagia followed by adequate medical therapy. Proton pump inhibitors are effective for preventing the recurrence of strictures after dilation. In young patients and patients with strictures that are difficult to dilate or need frequent dilations, surgery may be required; however, results can be disappointing.

Association of obesity with hiatal hernia and esophagitis

OBJECTIVE

Although weight loss is commonly recommended for symptoms of gastroesophageal reflux, a relationship between excessive body weight and esophageal reflux has not been established. The aim of this study was to determine whether obesity is associated with the presence of a hiatal hernia (HH) and/or an endoscopic diagnosis of esophagitis.

METHODS

Retrospective case control studies were done using 1389 patients who underwent gastric analysis and upper GI endoscopy between 1974 and 1995. After excluding patients with Zollinger-Ellison syndrome, 189 cases of esophagitis with 1024 controls were identified. In a separate analysis of the database, 151 cases of HH with 1053 controls were also identified. Patients were classified by body mass index (BMI) as: thin (BMI <20 kg/m2), normal (BMI 20-25), mildly obese (BMI 25-30), and obese (BMI >30).

RESULTS

Excessive body weight was significantly associated with the presence of HH, the probability of HH increasing with each level of BMI (p < 0.01), as well as with esophagitis (OR 1.8; 95% CI 1.4-2.1). HH was independently associated with esophagitis (OR 4.2 95% CI 2.9-6.1); when controlled for the effect of HH, the association between BMI and esophagitis diminished but remained significant. In the population as a whole, for the presence of esophagitis multiple logistic regression indicates BMI and hiatal hernia were significant factors but gender and race did not appear to be.

CONCLUSIONS

Excessive body weight is a significant independent risk factor for hiatal hernia and is significantly associated with esophagitis, largely through an increased incidence of hiatal hernia. Whites are more likely to have the combination of esophagitis and hiatal hernia than are blacks.