A renewed insight into Barrett's esophagus: comparative histopathological analysis of esophageal columnar metaplasia

Role of ion transporters in the bile acid-induced esophageal injury

Barrett's esophagus (BE) is considered to be the most severe complication of gastro-esophageal reflux disease (GERD), in which the prolonged, repetitive episodes of combined acidic and biliary reflux result in the replacement of the squamous esophageal lining by columnar epithelium. Therefore, the acid-extruding mechanisms of esophageal epithelial cells (EECs) may play an important role in the defense. Our aim was to identify the presence of acid/base transporters on EECs and to investigate the effect of bile acids on their expressions and functions. Human EEC lines (CP-A and CP-D) were acutely exposed to bile acid cocktail (BAC) and the changes in intracellular pH (pHi) and Ca(2+) concentration ([Ca(2+)]i) were measured by microfluorometry. mRNA and protein expression of ion transporters was investigated by RT-PCR, Western blot, and immunohistochemistry. We have identified the presence of a Na(+)/H(+) exchanger (NHE), Na(+)/HCO3 (-) cotransporter (NBC), and a Cl(-)-dependent HCO3 (-) secretory mechanism in CP-A and CP-D cells. Acute administration of BAC stimulated HCO3 (-) secretion in both cell lines and the NHE activity in CP-D cells by an inositol triphosphate-dependent calcium release. Chronic administration of BAC to EECs increased the expression of ion transporters compared with nontreated cells. A similar expression pattern was observed in biopsy samples from BE compared with normal epithelium. We have shown that acute administration of bile acids differently alters ion transport mechanisms of EECs, whereas chronic exposure to bile acids increases the expression of acid/base transporters. We speculate that these adaptive processes of EECs represent an important mucosal defense against the bile acid-induced epithelial injury.

[Comparison of surgical patients with gastroesophageal reflux disease and Barrett's esophagus]

INTRODUCTION

Barrett's esophagus (BE) is the only known precursor of adenocarcinoma occuring in the lower third of the esophagus. According to statistics, severity and elapsed time of gastroesophageal reflux disease (GERD) are major pathogenetic factors in the development of Barrett's esophagus.

PATIENTS AND METHODS

In a retrospective study between 2001 and 2008, we compared the preoperative results (signs and sympthoms, 24 hour pH manometry, esophageal manometry, Bilitec) and treatment efficacy of 176 GERD patients and 78 BE patients, who have undergone laparoscopic Nissen procedure for reflux disease.

RESULTS

The two groups of patients had similar demographic features, and elapsed time of reflux sympthoms were also equal. Both groups were admitted for surgery after a median time of 1.5 years (19.87 vs. 19.20 months) of ineffective medical (proton pump inhibitors) treatment. Preoperative functional tests showed a more severe presence of acid reflux in the BE group (DeMeester score 18.9 versus 41.9, p < 0.001). On the other hand, mano-metry - despite confirming lower esophageal sphincter (LES) damage - did not show difference between the two groups (12.10 vs. 12.57 mmHg, p = 0.892). We did not experience any mortality cases with laparoscopic antireflux procedures, although in two cases we had to convert during the operation (1 due to extensive adhesions, and 1 due to injury to the spleen). 3 months after the procedure - according to Visick score - both groups experienced a significant decrease, or lapse in reflux complaints (group I: 73%, group II: 81% of patients), LES functions improved (17.58 vs.18.70 mmHg), and the frequency and exposition of acid reflux decreased (DeMeester score 7.73 vs. 12.72).

CONCLUSION

The severity of abnormal acid reflux occuring parallel with the incompetent function of the damaged LES triggers not only inflammation in the gastroesophageal junction (GEJ), but also metaplastic process, and the development of Barrett's esophagus. Laparoscopic Nissen procedure for reflux disease can further improve outcome among patients with GERD not responding to conservative therapy.

A pSMAD/CDX2 complex is essential for the intestinalization of epithelial metaplasia

The molecular mechanisms leading to epithelial metaplasias are poorly understood. Barrett's esophagus is a premalignant metaplastic change of the esophageal epithelium into columnar epithelium, occurring in patients suffering from gastroesophageal reflux disease. Mechanisms behind the development of the intestinal subtype, which is associated with the highest cancer risk, are unclear. In humans, it has been suggested that a nonspecialized columnar metaplasia precedes the development of intestinal metaplasia. Here, we propose that a complex made up of at least two factors needs to be activated simultaneously to drive the expression of intestinal type of genes. Using unique animal models and robust in vitro assays, we show that the nonspecialized columnar metaplasia is a precursor of intestinal metaplasia and that pSMAD/CDX2 interaction is essential for the switch toward an intestinal phenotype.

Molecular mechanisms responsible for pathogenesis of Barrett's esophagus

Barrett's esophagus (BE) is defined as the metaplastic conversion of the distal esophageal squamous epithelium to intestinalized columnar epithelium. It is a premalignant condition associated with esophageal adenocarcinoma (EAC) and is the major risk factor for EAC. Recent studies suggest that the molecular mechanisms responsible for the pathogenesis of BE are closely related to transcription factors, signaling proteins and microRNAs (miRNAs). MiRNAs are expected to be used as novel biomarkers for the diagnosis, prognosis assessment and targeted treatment of EAC. This article summarizes recent results involving stem cells, immune factors, transcription factors, DNA methylation, nitric oxide, signaling pathways, microRNAs in the development of BE. Understanding of the molecular mechanisms behind the pathogenesis of BE has important implications for improved management of BE and EAC.

Paucity of synaptophysin-expressing cells in Barrett's mucosa

AIMS

To assess synaptophysin expression in columnar-lined oesophageal mucosa showing either goblet cells, known as intestinal metaplasia, or with accompanying oxyntic glands or pyloric glands.

METHODS AND RESULTS

Of 159 biopsies, 53 were oesophageal (19 had intestinal metaplasia, 13 oxyntic glands, and 21 pyloric glands), 77 gastric (12 had goblet cells and 27 no goblet cells) and 29 duodenal. Synaptophysin-positive goblet cells were found in all biopsies from the normal duodenum, in 53% of the oesophageal biopsies showing intestinal metaplasia, but only in 8% of gastric biopsies showing intestinal metaplasia. Synaptophysin-positive Paneth cells occurred in all duodenal biopsies, and in nine of the gastric biopsies showing intestinal metaplasia, but in only one of the oesophageal biopsies showing intestinal metaplasia. A continuous synaptophysin-positive neck cell zone was found in all biopsies from the normal antrum, but in none of the oesophageal biopsies with pyloric glands or with chronic antritis.

CONCLUSIONS

The paucity or absence of synaptophysin-positive cells in all three phenotypes of Barrett's mucosa might mirror a sequela of chronic inflammation caused by the particular pathogenic bacteria present in the immediate oesophageal microenvironment.

Columnar-lined esophagus in Chinese patients with proximal gastric carcinomas

OBJECTIVE

To investigate the clinicopathological features of columnar-lined esophagus (CLE) in Chinese patients.

METHODS

Among 182 consecutive resections of proximal gastric cancer with residual esophageal tissue, 114 were eligible for the study. The maximal lengths of CLE and superficial esophageal glands (SEG) and the presence or absence of chronic inflammation (CI), lymphoid follicles (LF), Helicobacter pylori (H. pylori) infection, intestinal metaplasia (IM), pancreatic metaplasia (PM) and dysplasia were analyzed and compared with those in the adjacent proximal gastric mucosa.

RESULTS

SEG were present in 110 cases with a mean length of 5.4 mm (range 1-16 mm, 90% equal to or under 10 mm and 10% between 11-16 mm). These glands were associated with CI (95%), LF (85%), H. pylori infection (42%), IM (25%), PM (36%) and dysplasia (10%). CLE was found in 65% of the cases and was associated with SEG (mean length of 4.0 mm, range 1-13 mm, 97% within 10 mm and 3% between 11-13 mm). The frequencies of CI (97%), LF (86%), H. pylori infection (65%) and PM (46%) in CLE were similar to those in the proximal stomach (CI 90%, LF 54%, H. pylori infection 58%, PM 39%). In contrast, the frequencies of IM (37%) and dysplasia (15%) in CLE were significantly lower than those in the proximal stomach (66% and 31%, respectively; P < 0.01).

CONCLUSIONS

CLE in Chinese patients was within 10 mm in length in 97% of cases, and with SEG and H. pylori infection-related changes similar to those in the proximal stomach.