Oesophageal pH has a power-law distribution in control and gastro-oesophageal reflux disease subjects

Metabolomic profiling of extraesophageal reflux disease in children

Although respiratory symptoms in children are often attributed to gastroesophageal reflux disease, establishing a clear diagnosis of extraesophageal reflux disease (EERD) can be challenging, as there are no sensitive or specific EERD biomarkers. The aim of this study was to evaluate the metabolite profile in bronchoalveolar (BAL) fluid from children with suspected EERD and assess the impact of reflux treatment on these metabolites. In this prospective pilot study, we performed nontargeted global metabolomic profiling on BAL fluid from 43 children undergoing testing with bronchoscopy, upper endoscopy, and multichannel intraluminal impedance with pH (pH-MII) for evaluation of chronic respiratory symptoms. Twenty-three (54%) patients had an abnormal pH-MII study. Seventeen (40%) patients were on proton pump inhibitors (PPIs) for testing. Levels of histamine, malate, adenosine 5'-monophosphate, and ascorbate were significantly lower in subjects with abnormal pH-MII studies compared to those normal studies. Furthermore, in children off PPI therapy, those with abnormal pH-MII studies had robust increases in a number of glycerophospholipids within phospholipid metabolic pathways, including derivatives of glycerophosphorylcholine, glycerophosphoglycerol, and glycerophosphoinositol, compared to those with normal pH-MII studies. These findings offer insight into the impact of reflux and PPIs on the lungs and provide a foundation for future studies using targeted metabolomic analysis to identify potential biomarkers of EERD.

Exploring the physiologic role of human gastroesophageal reflux by analyzing time-series data from 24-h gastric and esophageal pH recordings

Our previous finding of a fractal pattern for gastric pH and esophageal pH plus the statistical association of sequential pH values for up to 2 h led to our hypothesis that the fractal pattern encodes information regarding gastric acidity and that depending on the value of gastric acidity, the esophagus can signal the stomach to alter gastric acidity by influencing gastric secretion of acid or bicarbonate. Under our hypothesis values of gastric pH should provide information regarding values of esophageal pH and vice versa. We used vector autoregression, a theory‐free set of inter‐related linear regressions used to measure relationships that can change over time, to analyze data from 24‐h recordings of gastric pH and esophageal pH. We found that in pH records from normal subjects, as well as from subjects with gastroesophageal reflux disease alone and after treatment with a proton pump inhibitor, gastric pH values provided important information regarding subsequent values of esophageal pH and values of esophageal pH provided important information regarding subsequent values of gastric pH. The ability of gastric pH and esophageal pH to provide information regarding subsequent values of each other was reduced in subjects with gastroesophageal reflux disease compared to normal subjects. Our findings are consistent with the hypothesis that depending on the value of gastric acidity, the esophagus can signal the stomach to alter gastric acidity, and that this ability is impaired in subjects with gastroesophageal reflux disease.

We found that in pH records from normal subjects, as well as from subjects with gastroesophageal reflux disease alone and after treatment with a proton pump inhibitor, gastric pH values provided important information regarding subsequent values of esophageal pH and values of esophageal pH provided important information regarding subsequent values of gastric pH. Our findings are consistent with the hypothesis that depending on the value of gastric acidity, the esophagus can signal the stomach to alter gastric acidity, and that this ability is impaired in subjects with gastroesophageal reflux disease.

Reactive nitrogen oxide species induce dilatation of the intercellular space of rat esophagus

OBJECTIVE

Dilatation of the intercellular space (DIS) of the esophageal epithelium is recognized as one of the earliest histological changes in gastroesophageal reflux disease patients. At the human gastroesophageal junction, reactive nitrogen oxide species (RNOS) are generated luminally through the entero-salivary re-circulation of dietary nitrate. In cases with gastroesophageal reflux, the site of luminal RNOS generation may shift to the distal esophagus. The aim of this study was to investigate whether luminal RNOS exposure could be involved in the pathogenesis of DIS.

MATERIAL AND METHODS

Rat esophageal mucosa was studied with an Ussing chamber model. On the luminal side of the chamber, RNOS were generated by the acidification of physiologic concentrations of sodium nitrite (1.0 or 5.0 mM). Esophageal barrier function was assessed by means of electrophysiological transmembrane resistance and membrane permeability by means of (3)H-mannitol flux. The dimensions of the intercellular spaces were assessed by using transmission electron microscopy.

RESULTS

Administration of acid plus sodium nitrite induced DIS of the esophageal epithelium, and this ultrastructural morphological change was accompanied by a concomitant decrease in the transmembrane resistance and an increase in the epithelial permeability. The DIS induced by luminal RNOS was also confirmed in an in vivo exposure model.

CONCLUSIONS

The present animal study indicates that the RNOS generated by the acidification of salivary nitrite in the presence of refluxed gastric acid in the esophagus could be a luminal factor that is responsible for the induction of DIS. Further studies are warranted to investigate the clinical relevance of the present findings to the human situation.

Continuous distal oesophageal acidification decreases postprandial gastric acidity in healthy human subjects

BACKGROUND

Previously, we hypothesized that exposing the distal oesophagus to acid signals the stomach to decrease gastric acidity.

AIM

To test the hypothesis that exposing the distal oesophagus to acid signals the stomach to decrease gastric acidity.

METHODS

Twenty-two healthy humans ingested a standard meal containing [(14)C]octanoic acid and [(13)C]glycine over 30 min on 2 separate occasions. Gastric pH was measured for 90 min before and 240 min after the meal. 10 mm HCl was infused continuously at 1 mL/min into either the distal oesophagus or stomach in a 2-way crossover fashion for 60 min before and 240 min after the meal. Gastric emptying of solid and liquid were determined with breath tests.

RESULTS

Compared to gastric infusion, oesophageal infusion significantly decreased gastric acidity after the meal, but not before the meal and the magnitude of the decrease varied directly with gastric acidity. Gastric emptying of solid or liquid with oesophageal infusion was not significantly different from that with gastric infusion.

CONCLUSIONS

These findings support the hypothesis of the existence of a physiological oesophago-gastric feedback mechanism that might contribute to regulation of postprandial gastric acidity. Oesophageal acidification might decode gastric information and signal the stomach to decrease gastric acidity. Further studies are needed to assess the characteristics of such feedback mechanism in-patients with gastro-oesophageal reflux disease (GERD).