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

The function and immune role of cuproptosis associated hub gene in Barrett's esophagus and esophageal adenocarcinoma

Barrett's esophagus (BE) is a precancerous lesion of esophageal adenocarcinoma (EAC), with approximately 3-5% of patients developing EAC. Cuproptosis is a kind of programmed cell death phenomenon discovered in recent years, which is related to the occurrence and development of many diseases. However, its role in BE and EAC is not fully understood. We used single sample Gene Set Enrichment Analysis (ssGSEA) for differential analysis of BE in the database, followed by enrichment analysis of Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO) and GSEA, Protein-Protein Interaction (PPI), Weighted Gene Co-expression Network Analysis (WGCNA), Receiver Operating Characteristic Curve (ROC) and finally Quantitative Real Time Polymerase Chain Reaction (qRT-PCR) and immunohistochemistry (IHC) of clinical tissues. Two hub genes can be obtained by intersection of the results obtained from the cuproptosis signal analysis based on BE. The ROC curves of these two genes predicted EAC, and the Area Under the Curve (AUC) values could reach 0.950 and 0.946, respectively. The mRNA and protein levels of Centrosome associated protein E (CENPE) and Shc SH2 domain binding protein 1 (SHCBP1) were significantly increased in clinical EAC tissues. When they were grouped by protein expression levels, high expression of CENPE or SHCBP1 had a poor prognosis. The CENPE and SHCBP1 associated with cuproptosis may be a factor promoting the development of BE into EAC which associated with the regulation of NK cells and T cells.

Relationship Between Pepsin Expression and Dysplasia Grade in Patients With Vocal Cord Leukoplakia

OBJECTIVE

To measure pepsin expression in patients with vocal fold leukoplakia and elucidate its clinical significance.

STUDY DESIGN

Retrospective analysis of pathologic archive specimens.

SETTING

Affiliated university hospital.

SUBJECTS AND METHODS

The study included 45 patients with vocal fold leukoplakia and 19 with vocal fold polyps who underwent surgical treatment between December 2013 and July 2016. Masses were detected on both vocal cords in 5 patients with vocal fold leukoplakia and in 1 patient with vocal fold polyps. Immunohistochemistry was used to assess pepsin expression. In addition, the relationship of pepsin expression level with clinical characteristics of vocal fold leukoplakia was assessed.

RESULTS

The rate of pepsin expression was high in the polyp group (75%) and the leukoplakia group (68%); however, the difference between groups was not significant (P > .05). Pepsin expression significantly increased according to grade of dysplasia (mild, 57.1%; moderate, 88.9%; severe, 100.0%; P = .034). Similarly, the percentage of lesions that exhibited strongly positive pepsin expression increased with the grade of dysplasia (mild, 37.1%; moderate, 66.7%; severe, 100.0%; P = .005). The leukoplakia recurrence rate was higher in patients with positive pepsin expression than in patients with negative pepsin expression but without a significant difference (P > .05).

CONCLUSION

Our study suggests that pepsin was associated with the grade of dysplasia of vocal cord leukoplakia. Further investigation with appropriate control groups and controlling for other risk factors, such as smoking or alcohol consumption, is needed.

Salivary Gland Choristoma: A Rare Finding at the Gastroesophageal Junction

A choristoma is a tumor-like outgrowth consisting of heterotopic, histologically mature tissue located at an anatomically unusual part of the body. Salivary gland choristoma at the gastrointestinal junction (GEJ) is an extremely rare entity with only one other case reported in the literature. In this report, we present the case of an 87-year-old female with long-standing gastroesophageal reflux disease (GERD) history who was incidentally found to have salivary gland choristoma at GEJ through an upper endoscopy-guided biopsy. We suggest that the finding of salivary gland choristoma at the GEJ could be metaplasia secondary to the patient’s long-standing history of GERD with esophagitis.

Cryospray ablation using pressurized CO2 for ablation of Barrett's esophagus with early neoplasia: early termination of a prospective series

BACKGROUND

Cryotherapy is a relatively novel ablation modality for the endoscopic ablation of Barrett's esophagus (BE). Data on the use of pressurized carbon dioxide (CO2) gas for cryoablation are scarce.

STUDY AIM

To determine the efficacy and safety of cryospray ablation using pressurized CO2 gas in the treatment of BE with early neoplasia.

METHODS

In this prospective single center case series, we aimed to include 30 patients with BE and early neoplasia. Nodular neoplastic lesions were treated with endoscopic mucosal resection (EMR). Residual BE mucosa was treated with cryospray ablation every 4 weeks until the complete BE segment was eliminated or up to seven treatment sessions. If no reduction of the BE segment was observed after two subsequent treatment sessions, cryoablation was terminated. Patients were contacted at days 1 and 4 post-treatment to evaluate the level of discomfort. Endoscopic and histologic follow-up evaluations were performed up to 24 months post-treatment.

RESULTS

After the inclusion of 10 patients, insufficient effect of cryoablation was observed, resulting in early termination of the study. In total, seven patients with intramucosal carcinoma (IMC) and three with high grade dysplasia (HGD) were included. Prior EMR was performed in nine patients. A median of 2.5 (IQR 2.0 - 4.0) cryoablation sessions were performed. At 6 months of follow-up, complete eradication of intestinal metaplasia was observed in 11 % (1 /9; one patient died, not treatment or disease related) of the patients and complete eradication of dysplasia in 44 % (4 /9). In three patients, HGD or IMC was detected during follow-up, and was endoscopically treated. Apart from a gastric perforation as a result of gastric distension caused by CO2 gas during the first treatment, cryospray treatments were well tolerated.

CONCLUSION

After a short learning curve, cryoablation using CO2 gas was found to be a safe and well tolerated treatment modality. However, in our experience, the efficacy of CO2 cryoablation combined with EMR for nodular lesions is disappointing for the treatment of BE associated neoplasia.

Barrett oesophagus: lessons on its origins from the lesion itself

Barrett oesophagus develops when the lower oesophageal squamous epithelium is replaced with columnar epithelium, which shows both intestinal and gastric differentiation. No consensus has been reached on the origin of Barrett oesophagus. Theories include a direct origin from the oesophageal-stratified squamous epithelium, or by proximal migration of the gastric cardiac epithelium with subsequent intestinalization. Variations of this theory suggest the origin is a distinctive cell at the squamocolumnar junction, the oesophageal gland ducts, or circulating bone-marrow-derived cells. Much of the supporting evidence comes from experimental models and not from studies of Barrett mucosa. In this Perspectives article, we look at the Barrett lesion itself: at its phenotype, its complexity, its clonal architecture and its stem cell organization. We conclude that Barrett glands are unique structures, but share many similarities with gastric glands undergoing the process of intestinal metaplasia. We conclude that current evidence most strongly supports an origin from stem cells in the cardia.

Familial clustering of Barrett's esophagus and esophageal adenocarcinoma in a European cohort

BACKGROUND & AIMS

Up to 7% of cases of Barrett's esophagus (BE) or esophageal adenocarcinoma (EAC) in the United States occur in family clusters. We identified first-degree and second-degree relatives of patients with BE and EAC to determine the extent of familial clustering in a European cohort and studied differences between familial and nonfamilial cases.

METHODS

A questionnaire was sent to all patients diagnosed with BE or EAC from 2000-2011 at 3 hospitals in the Netherlands (n = 838). Diagnoses of affected relatives were confirmed by using the Dutch Pathology Registry. Familial statuses of BE were defined as definitive (≥1 first-degree or second-degree relative with BE or EAC), possible (≥1 reported relative with BE or esophageal cancer without histologic confirmation), unlikely (no family history), or unknown.

RESULTS

A total of 603 patients with BE or EAC (71%) responded and were included in the analysis. Familial BE was definitive for 7% of cases (n = 39, 10% of first-degree relatives affected), possible for 6% (n = 36), unlikely for 49% (n = 297), and unknown for 38% (n = 231). Definitive cases of familial BE were younger at onset of heartburn and EAC diagnosis; their first-degree relatives more frequently had reflux symptoms and a prior upper endoscopy, compared with unlikely cases of familial BE.

CONCLUSIONS

In a database analysis of patients diagnosed with BE or EAC in the Netherlands, 7% of cases of BE and EAC were familial. These cases have a younger average age of onset of reflux symptoms and diagnosis of EAC than unlikely familial cases. These findings may indicate that genetic factors contribute to BE susceptibility, with a possible central role of gastroesophageal reflux.

Toll-like receptor 4 activation in Barrett's esophagus results in a strong increase in COX-2 expression

BACKGROUND

Barrett's esophagus (BE) is known to progress to esophageal adenocarcinoma in a setting of chronic inflammation. Toll-like receptor (TLR) 4 has been linked to inflammation-associated carcinogenesis. We aimed to determine the expression and functional activity of TLR4 in the esophagus and whether TLR4 activation in BE could promote carcinogenesis by inducing COX-2 expression.

METHODS

TLR4 expression in esophageal adenocarcinoma, BE, duodenum, reflux esophagitis and normal squamous esophagus biopsies was assessed using real-time PCR and validated by in situ hybridization and immunohistochemistry. Ex vivo cultures of BE, duodenum and normal squamous esophagus biopsies and a BE cell line (BAR-T) were stimulated with the TLR4 agonist lipopolysaccharide (LPS). To evaluate the effect of TLR4 activation, NF-κB activation, IL8 secretion and expression and COX-2 expression were determined.

RESULTS

TLR4 expression was significantly increased in esophageal adenocarcinoma, BE, duodenum and reflux esophagitis compared to normal squamous esophagus. LPS stimulation resulted in NF-κB activation and a dose-dependent increase of IL8 secretion and mRNA expression. The induction of IL8 was more evident in BE compared to normal squamous esophagus. Upon LPS stimulation, COX-2 expression increased significantly in ex vivo cultured BE biopsies, which was observed in both epithelium and lamina propria cells. However, no effect was found in duodenum and normal squamous esophagus biopsies.

CONCLUSION

TLR4 activation in BE results in a strong increase in COX-2 and may contribute to malignant transformation.

Involvement of luminal nitric oxide in the pathogenesis of the gastroesophageal reflux disease spectrum

Over the last 3 decades, the incidence of esophageal adenocarcinoma has dramatically increased in Western countries; a similar increase may be observed in Asian countries in the near future. Esophageal adenocarcinoma arises from a sequential gastroesophageal reflux disease (GERD) spectrum from reflux erosive esophagitis, to Barrett's esophagus, and finally to esophageal adenocarcinoma. At present, gastric acid and bile are assumed to be primarily involved in the etiology of the GERD spectrum. We reported in 2002 that, at the gastroesophageal junction in humans, abundant amounts of nitric oxide (NO) are generated luminally through the entero-salivary re-circulation of dietary nitrate. Since then, we have carried out a series of experiments to demonstrate that NO diffuses into the adjacent epithelium at cytotoxic levels. This diffusion results in disruption of the epithelial barrier function, exacerbation of inflammation, acceleration of columnar transformation in the esophagus (Barrett's esophagus) via the induction of caudal-type homeobox 2, and the shifting of carcinogenic N-nitroso compound formation from the luminal to epithelial compartment. These results suggest that, in addition to conventionally recognized causative factors, luminal NO could also be involved in the pathogenesis of the GERD spectrum. In addition, we recently showed that there is a prominent gender-related difference in NO-related cytotoxicity in the esophagus and that estrogen attenuated the esophageal tissue damage via the estrogen receptor in female rats. The role of estrogen in attenuating the esophageal tissue damage in NO-related esophageal damage could explain the well-recognized male predominance in the GERD spectrum in humans.

Chronic pepsin exposure promotes anchorage-independent growth and migration of a hypopharyngeal squamous cell line

OUTCOME OBJECTIVES

(1) Investigate the role of reflux, specifically pepsin, in laryngopharyngeal carcinogenesis. (2) Evaluate effects of chronic pepsin exposure on cell migration, apoptosis, and colony-forming ability in hypopharyngeal cells.

STUDY DESIGN

Translation research.

SETTING

Academic research laboratory.

METHODS

Human hypopharyngeal squamous carcinoma FaDu cells were chronically exposed to nonacidic pepsin (exposed for 24 hours, 4 times over 2 weeks at the following concentrations: 0.01 mg/mL, 0.1 mg/mL, or 1 mg/mL). Precise wounds were created in confluent cell plates, and rates of cell migration into wounds were quantified. Separately, cell viability of chronic pepsin-exposed FaDu cells acutely treated with paclitaxel was measured. Finally, a clonogenic assay was performed on these cells to measure effects of chronic pepsin exposure on colony-forming ability.

RESULTS

An increased rate of relative wound density was observed in chronic pepsin-treated (0.01 mg/mL, 0.1 mg/mL) cells compared with control (P < .001), suggesting greater rates of cell migration. Pepsin-treated (0.1 mg/mL) cells demonstrated on average greater cell viability compared with control after exposure to paclitaxel, suggesting possible apoptotic resistance; however, this was not statistically significant. Chronic pepsin exposure (0.1 mg/mL, 1 mg/mL) was associated with a dose-dependent increase in colony-forming ability relative to control (P < .001).

CONCLUSION

Hypopharyngeal squamous cell line chronically exposed to pepsin demonstrated increased cell migration and colony-forming ability relative to control cells. These experiments indicate that chronic pepsin exposure acts as a promoter of tumorigenesis and metastasis of airway epithelium, suggesting a role for pepsin in laryngopharyngeal carcinogenesis attributed to gastric reflux.

Adhesion GPCRs are widely expressed throughout the subsections of the gastrointestinal tract

Background

G protein-coupled receptors (GPCRs) represent one of the largest families of transmembrane receptors and the most common drug target. The Adhesion subfamily is the second largest one of GPCRs and its several members are known to mediate neural development and immune system functioning through cell-cell and cell-matrix interactions. The distribution of these receptors has not been characterized in detail in the gastrointestinal (GI) tract. Here we present the first comprehensive anatomical profiling of mRNA expression of all 30 Adhesion GPCRs in the rat GI tract divided into twelve subsegments.

Methods

Using RT-qPCR, we studied the expression of Adhesion GPCRs in the esophagus, the corpus and antrum of the stomach, the proximal and distal parts of the duodenum, ileum, jejunum and colon, and the cecum.

Results

We found that twenty-one Adhesion GPCRs (70%) had a widespread (expressed in five or more segments) or ubiquitous (expressed in eleven or more segments) distribution, seven (23%) were restricted to a few segments of the GI tract and two were not expressed in any segment. Most notably, almost all Group III members were ubiquitously expressed, while the restricted expression was characteristic for the majority of group VII members, hinting at more specific/localized roles for some of these receptors.

Conclusions

Overall, the distribution of Adhesion GPCRs points to their important role in GI tract functioning and defines them as a potentially crucial target for pharmacological interventions.

An analysis of esophagectomy and other techniques in the management of high-grade dysplasia of Barrett's esophagus

Barrett's esophageal (BE) metaplasia is a premalignant condition of the distal esophagus that develops as a consequence of gastroesophageal reflux disease. The progression to carcinogenesis results from progressive dysplastic changes of the metaplastic epithelium through low-grade and then high-grade dysplasia (HGD) to eventually adenocarcinoma of the esophagus. The management of HGD is controversial with proponents for each of the three major management strategies: endoscopic surveillance, endoscopic ablative therapies, and esophagectomy. The aim of the study was to define and discuss the various management strategies of HGD arising from BE metaplasia. There is a paucity of randomized controlled data from which to draw definitive conclusions. All strategies for the management of HGD are reasonable options and are complimentary. BE with HGD is a malignant lesion. A multidisciplinary approach individualizing therapy should be undertaken when possible. Esophageal resection should be reserved for otherwise healthy patients. Endoscopic techniques are viable alternatives to surgery.

Intercellular space volume is mainly increased in the basal layer of esophageal squamous epithelium in patients with GERD

BACKGROUND/AIMS

At present, the dilation of esophageal intercellular spaces (ICS) is considered an early morphologic marker of acid damage in patients with GERD. Nevertheless, previous electron microscopic (EM) studies had focused only on the suprabasal layer of squamous epithelium or did not nearly specify which layer of squamous epithelium was studied. Therefore, we aimed to assess the volumetric amount of the ICS in all layers of SE in patients with GERD.

METHODS

In this study, 48 patients were prospectively included (NERD = 18, ERD = 17; Barrett's esophagus = 5, controls = 8). All patients with ERD and NERD had typical reflux symptoms, as assessed by a valid GERD questionnaire. ICS volume was assessed by electron microscopy in the superficial, prickle cell, and basal layers of esophageal squamous epithelium using the method of Weibel.

RESULTS

ERD was associated with increased ICS volume in the basal layer (LA-A, p = 0.038; LA-B, p = 0.005) and prickle cell layer (LA-A, p = 0.006; LA-B, p = 0.007) as compared to controls. Comparisons between NERD and ERD patients revealed more dilated ICS in the basal layer (LA-B, p = 0.007), prickle cell layer (LA-A, p = 0.008; LA-B, p = 0.001) and superficial layer (LA-B, p = 0.018) in patients with ERD.

CONCLUSIONS

Not only the diameter but also the volume of the ICS is increased in patients with GERD. Furthermore, the dilation of ICS is present in all three layers of the SE, being more pronounced in the basal layer. These findings support the concept that the impairment of the esophagus begins in the deeper parts of the esophageal epithelium.

Ectopic Cdx2 expression in murine esophagus models an intermediate stage in the emergence of Barrett's esophagus

Barrett's esophagus (BE) is an intestinal metaplasia that occurs in the setting of chronic acid and bile reflux and is associated with a risk for adenocarcinoma. Expression of intestine-specific transcription factors in the esophagus likely contributes to metaplasia development. Our objective was to explore the effects of an intestine-specific transcription factor when expressed in the mouse esophageal epithelium. Transgenic mice were derived in which the transcription factor Cdx2 is expressed in squamous epithelium using the murine Keratin-14 gene promoter. Effects of the transgene upon cell proliferation and differentiation, gene expression, and barrier integrity were explored. K14-Cdx2 mice express the Cdx2 transgene in esophageal squamous tissues. Cdx2 expression was associated with reduced basal epithelial cell proliferation and altered cell morphology. Ultrastructurally two changes were noted. Cdx2 expression was associated with dilated space between the basal cells and diminished cell-cell adhesion caused by reduced Desmocollin-3 mRNA and protein expression. This compromised epithelial barrier function, as the measured trans-epithelial electrical resistance (TEER) of the K14-Cdx2 epithelium was significantly reduced compared to controls (1189 Ohm*cm(2) ±343.5 to 508 Ohm*cm(2)±92.48, p = 0.0532). Secondly, basal cells with features of a transitional cell type, intermediate between keratinocytes and columnar Barrett's epithelial cells, were observed. These cells had reduced keratin bundles and increased endoplasmic reticulum levels, suggesting the adoption of secretory-cell features. Moreover, at the ultrastructural level they resembled "Distinctive" cells associated with multilayered epithelium. Treatment of the K14-Cdx2 mice with 5'-Azacytidine elicited expression of BE-associated genes including Cdx1, Krt18, and Slc26a3/Dra, suggesting the phenotype could be advanced under certain conditions. We conclude that ectopic Cdx2 expression in keratinocytes alters cell proliferation, barrier function, and differentiation. These altered cells represent a transitional cell type between normal squamous and columnar BE cells. The K14-Cdx2 mice represent a useful model to study progression from squamous epithelium to BE.

Biology of Barrett's esophagus and esophageal adenocarcinoma

The past few years have brought new advances in our understanding of the molecular mechanisms underlying the development of Barrett's esophagus and esophageal adenocarcinoma. Although knowledge of the genetic basis for these conditions has not yet translated into clinically useful biomarkers, the current pace of biomedical discovery holds endless possibilities for molecular medicine to improve the diagnosis and management of patients with these conditions. This article provides a useful conceptual basis for understanding the molecular events involved in the making of Barrett metaplasia and in its neoplastic progression, and provides a rationale for evaluating studies on the application of molecular medicine to the diagnosis and management of patients with Barrett's esophagus and esophageal adenocarcinoma.

The pathogenesis of Barrett's metaplasia and the progression to esophageal adenocarcinoma

The most important risk factor for the development of Barrett's esophagus is the reflux of both gastric and duodenal contents into the esophagus. The reason why Barrett's metaplasia develops only in a minority of patients suffering from gastroesophageal reflux disease remains unknown.The exact mechanism behind the transition of normal squamous epithelium into specialized columnar epithelium is also unclear. It is likely that stem cells are involved in this metaplastic change, as they are the only permanent residents of the epithelium. Several tumorigenic steps that lead to the underlying genetic instability, which is indispensable in the progression from columnar metaplasia to esophageal adenocarcinoma have been described. This review outlines the process of pathogenesis of Barrett's metaplasia and its progression to esophageal adenocarcinoma.

Exogenous luminal nitric oxide exposure accelerates columnar transformation of rat esophagus

Exposure of the esophageal mucosa to refluxed gastroduodenal contents is recognized to be an important risk factor for Barrett's esophagus (BE). At the human gastroesophageal junction, nitric oxide is generated luminally through the enterosalivary recirculation of dietary nitrate, and in cases with gastroesophageal reflux, the site of luminal nitric oxide generation could shift to the distal esophagus. The aim of this study is to investigate whether exogenous luminal nitric oxide could promote the development of BE in rats. Sodium nitrite plus ascorbic acid were administered to a rat surgical model of BE, in which the gastroduodenal contents were refluxed into the esophagus to generate exogenous luminal nitric oxide in the esophagus by the acid-catalyzed chemical reaction between the 2 reagents. The emergence of BE was evaluated histologically in the early phase (several weeks) after the surgery with or without exogenous nitric oxide administration. To elucidate the histogenesis of BE, CDX2, MUC2 and MUC6 expressions were investigated immunohistochemically. Coadministration of sodium nitrite plus ascorbic acid significantly accelerated the timing of emergence and increased the area of BE compared with controls. Administration of either reagent alone did not show any promotive effects on BE formation. Immunohistochemically, the columnar epithelium thus induced was similar to the specialized intestinal metaplasia in human BE. The results of this animal model study suggest that exogenous luminal nitric oxide could be involved in the pathogenesis of the columnar transformation of the esophagus. Further studies in human are warranted.

Barrett's esophagus and Cornelia de Lange Syndrome

AIM

To review the records of Cornelia de Lange Syndrome (CDLS) children, affected by Gastro-oesophageal reflux disease (GERD), to detect the presence of Barrett's Esophagus (BE).

METHODS

A total of 62 CDLS patients were investigated for GERD (1 month-35 years). In all of them a pH-metry, an upper endoscopy with multiple biopsies and a complete radiologic digestive evaluation were carried out. BE was diagnosed in case of replacement of oesophageal mucosa by specialized intestinal-type columnar mucosa. Anti-reflux surgery was considered in case of persistence of BE after medical therapy. Follow-up (mean 3.5 years) consisted in endoscopy every 6 months .

RESULTS

Gastro-oesophageal reflux disease was found in 50 CDLS patients (80%) and BE in six of them (12% of the GERD group, 9.6% of the entire population, mean age 17 years, range 6-32 years). A short segment BE was observed in three patients, a long one in two patients and an infiltrating adenocarcinoma of the lower oesophagus in one patient.

CONCLUSIONS

A higher frequency of BE in CDLS patients than in a normal population is found. A delayed diagnosis because of atypical GERD symptoms and an altered intestinal motility as a result of neurological impairment can be recognized as the main cause.

Platelet 12-lipoxygenase and stem cells in Barrett's esophagus

Esophageal adenocarcinoma has shown a significant increase in incidence in recent years. It is thought that the development of gastroesophageal reflux disease (GERD), followed by columnar-lined esophagus and the development of dysplasia, leads to invasive adenocarcinoma. The exact pathogenesis of this process, the diagnosis and differentiation of the metaplastic and dysplastic esophageal lesions have yet to be determined. The purpose of this immunohistochemical study was to investigate the expression of pro-tumorigenic enzyme platelet 12-lipoxygenase (p12LOX) using two new available antibodies in non-dysplastic and dysplastic Barrett's esophagus. The stem cell markers nestin, CD117 and CD44, were then evaluated. The comparative group included GERD carditis, gastric intestinal metaplasia and colorectal adenoma. The overexpression of p12LOX detected by two specific antibodies in the non-dysplastic and dysplastic Barrett's mucosa clearly demonstrated that this enzyme plays an important role in the development of esophageal adenocarcinoma.

Cellular origin of Barrett's metaplasia and oesophageal stem cells

Barrett's oesophagus is a metaplastic pre-malignant disorder and the only established precursor lesion for oesophageal adenocarcinoma. Barrett's oesophagus develops when the normal stratified squamous epithelium of the lower oesophagus is replaced by a columnar lined mucosa with intestinal differentiation, usually in the context of chronic gastro-oesophageal reflux disease. The cellular and molecular mechanisms by which this metaplastic transformation occurs are poorly understood. Abnormal differentiation of multipotent stem cells in the squamous oesophagus, triggered by exposure to refluxate, is one potential mechanism. These stem cells could be located in the basal layer of the squamous oesophageal epithelium and/or in the neck region of the oesophageal submucosal gland ducts; however, their exact location and identification are still matter of discussion. Three-dimensional models combined with state-of-the-art imaging techniques are now applied to characterize the squamous epithelium in human oesophageal samples, and this could unveil essential information to identify these progenitor cells. Locating stem cells in human squamous oesophagus could have important implications for our understanding of Barrett's oesophagus and remarkably improve our future strategies for its prevention.

The role of acid and bile reflux in oesophagitis and Barrett's metaplasia

The precise mechanisms whereby gastro-oesophageal reflux disease causes reflux oesophagitis and Barrett's oesophagus are not clear, even though these diseases have been known to be linked for many years. Recent studies indicate a role for the reflux-induced inflammatory response of oesophageal squamous epithelial cells and the immune cells in the pathogenesis of reflux oesophagitis. Although reflux oesophagitis commonly heals with oesophageal squamous cell regeneration, in some individuals the oesophagus heals through the process of metaplasia, a condition termed Barrett's oesophagus. Recent studies indicate that individual differences in the reflux-mediated response of oesophageal squamous epithelial cells in the type of immune response and/or in signalling pathways that regulate cell proliferation or cell phenotype may determine whether the oesophagus heals with the regeneration of squamous cells or through Barrett's metaplasia.

Modelling Barrett's oesophagus

Barrett's oesophagus is the replacement of normal squamous oesophageal epithelium with an intestinalized columnar epithelium. Although some insight has been gained as to what Barrett's oesophagus is, how this columnar epithelium emerges from within a stratified squamous epithelium remains an unanswered question. We have sought to determine whether oesophageal keratinocytes can be trans-differentiated into Barrett's oesophagus cells. Using an Affymetrix microarray, we found unexpectedly that gene-expression patterns in the Barrett's oesophagus were only slightly more similar to the normal small intestine than they were to the normal oesophagus. Thus gene-expression patterns suggest significant molecular similarities remain between Barrett's oesophagus cells and normal squamous oesophageal epithelium, despite their histological resemblance with intestine. We next determined whether directed expression of intestine-specific transcription factors could induce intestinalization of keratinocytes. Retroviral-mediated Cdx2 (Caudal-type homeobox 2) expression in immortalized human oesophageal keratinocytes engineered with human telomerase reverse transcriptase (EPC2-hTERT cells) could be established transiently, but not maintained, and was associated with a reduction in cell proliferation. Co-expression of cyclin D1 rescued proliferation in the Cdx2-expressing cells, but co-expression of dominant-negative p53 did not. Cdx2 expression in the EPC2-hTERT.D1 cells did not induce intestinalization. However, when combined with treatments that induce chromatin remodelling, there was a significant induction of Barrett's oesophagus-associated genes. Studies are ongoing to determine whether other intestinal transcription factors, either alone or in combination, can provoke greater intestinalization of oesophageal keratinocytes. We conclude that, on the basis of gene-expression patterns, Barrett's oesophagus epithelial cells may represent an intermediate between oesophageal keratinocytes and intestinal epithelial cells. Moreover, our findings suggest that it may be possible to induce Barrett's oesophagus epithelial cells from oesophageal keratinocytes by altering the expression of certain critical genes.

Cdx genes, inflammation, and the pathogenesis of intestinal metaplasia

Intestinal metaplasia (IM) is a biologically interesting and clinically relevant condition in which one differentiated type of epithelium is replaced by another that is morphologically similar to normal intestinal epithelium. Two classic examples of this are gastric IM and Barrett's esophagus (BE). In both, a chronic inflammatory microenvironment, provoked either by Helicobacter pylori infection of the stomach or acid and bile reflux into the esophagus, precedes the metaplasia. The Caudal-related homeodomain transcription factors Cdx1 and Cdx2 are critical regulators of the normal intestinal epithelial cell phenotype. Ectopic expression of Cdx1 and Cdx2 occurs in both gastric IM as well as in BE. This expression precedes the onset of the metaplasia and implies a causal role for these factors in this process. We review the observations regarding the role of chronic inflammation and the Cdx transcription factors in the pathogenesis of gastric IM and BE.

Screening for Barrett's esophagus in asymptomatic women

BACKGROUND

Barrett's esophagus (BE) has been detected in approximately 10% of patients with chronic GERD. Previous studies demonstrated a similar prevalence of BE in asymptomatic adults.

OBJECTIVE

To determine the prevalence of BE in asymptomatic women.

DESIGN

We invited women scheduled for routine screening colonoscopy (for colorectal cancer) and women undergoing endoscopic examination before bariatric surgery to participate. Patients experiencing heartburn symptoms more than once per month were excluded.

SETTING

Outpatients at Stanford University and Palo Alto VA Health Care System.

INTERVENTIONS

Biopsies of the esophagogastric junction in the setting of suspected BE, and completion of symptom and health-related quality of life questionnaires to ensure that subjects were asymptomatic.

MAIN OUTCOME MEASUREMENT

Identification of BE.

RESULTS

We detected BE in 8 (6%) of 126 subjects, including 3 (5%) of 61 of the women in the colorectal cancer screening cohort and 5 (8%) of 65 of the women in the pre-bariatric surgery cohort, all of whom had BE measuring 2 cm or less (P = .30). Patients found to have BE were more likely to be older (mean age 60 years vs 49 years, respectively; P = .04), but there was no difference in mean body mass index, ethnicity, or tobacco or alcohol use between patients with and without BE. BE was only present in pre-bariatric surgery subjects younger than the age of 50 and was most common in the 61- to 70-year age cohort in both groups. Erosive esophagitis, microscopic reflux changes, and Helicobacter pylori infection were not more common in the pre-bariatric surgery group.

LIMITATION

Small number of subjects with BE detected.

CONCLUSIONS

Short-segment BE was detected in 6% of asymptomatic women undergoing screening endoscopic examinations.

Risk factors for the detection of Barrett's esophagus in patients with erosive esophagitis

BACKGROUND

Barrett's esophagus (BE) results from metaplastic healing of injured esophageal mucosa after erosive esophagitis (EE).

OBJECTIVE

Our purpose was to determine whether severity of esophagitis, indication for endoscopy, or proton pump inhibitor treatment affects the subsequent incidence of BE diagnosis in patients found to have EE on EGD performed for any indication.

DESIGN

We identified patients with primary or secondary International Classification of Diseases, 9th revision diagnosis codes of EE from 1996 to 2006 who had at least 2 EGDs on record. Patients with prevalent BE on the first EGD were excluded.

SETTING

Inpatients and outpatients at Stanford University and Palo Alto Veterans Affairs Health Care System.

INTERVENTIONS

Retrospective review of EGD and pathology reports to confirm BE.

MAIN OUTCOME MEASUREMENTS

Detection of BE after diagnosis of EE.

RESULTS

A total of 1095 patients were identified between 1996 and 2000, and 102 (9%) were included. Sixty-two (61%) patients were veterans, 87 (85%) were male, and 83 (81%) were white. The mean (+/-SD) age was 58 +/- 14 years (range 24-83 years). BE was detected in 9 (9%) patients (95% CI, 4.5%-17.6%) over a mean of 13.3 +/- 5.7 months (range 1-53.5 months), and all had prior grade 4 esophagitis. The mean BE length was 4 +/- 1.8 cm (range 1-18 cm). Six patients had upper GI bleeding as the indication for EGD, whereas the other 3 complained of dysphagia. The association of grade 4 esophagitis (P = .01) and GI hemorrhage (P = .01) to the subsequent detection of BE was highly statistically significant.

LIMITATIONS

Retrospective study, small number of patients with BE after EE. All patients were receiving care at tertiary medical centers.

CONCLUSIONS

BE was detected in 9% of patients with prior EE and was detected exclusively on follow-up of patients with severe esophagitis. The majority of the patients found to have BE had upper GI bleeding as the presentation for EGD.

Induction of intestinalization in human esophageal keratinocytes is a multistep process

Barrett's esophagus (BE) is the replacement of normal squamous esophageal mucosa with an intestinalized columnar epithelium. The molecular mechanisms underlying its development are not understood. Cdx2 is an intestine-specific transcription factor that is ectopically expressed in BE, but its role in this process is unclear. Herein, we describe a novel cell culture model for BE. Retroviral-mediated Cdx2 expression in immortalized human esophageal keratinocytes [EPC-human telomerase reverse transcriptase (hTERT)] could transiently be established but not maintained and was associated with a reduction in cell proliferation. Coexpression of cyclin D1, but not a dominant-negative p53, rescued proliferation in the Cdx2-expressing cells. Cdx2 expression in the EPC-hTERT.D1 cells decreased cell proliferation but did not induce intestinalization. We investigated for other treatments to enhance intestinalization and found that acidic culture conditions uniformly killed EPC-hTERT.D1.Cdx2 cells. However, treatment with 5-aza-2-deoxycytidine (5-AzaC) to demethylate epigenetically silenced genes did appear to be tolerated. Multiple Cdx2 target genes, markers of intestinal differentiation and markers of BE, were induced by this 5-AzaC treatment. More interestingly, the expression level of several of these genes was enhanced only in the EPC-hTERT.D1-Cdx2 cells treated with 5-AzaC. Two of these, SLC26a3/DRA (downregulated in adenoma) and Na+/H+ exchanger 2 (NHE2), were not previously known to be elevated in BE; however, we confirmed their elevation in BE tissue samples. 5-AzaC treatment also induced cell senescence, even at low doses. We conclude that ectopic proliferation signals, alterations in epigenetic gene regulation and the inhibition of tumor suppressor mechanisms are required for Cdx2-mediated intestinalization of human esophageal keratinocytes in BE.

Acid, bile, and CDX: the ABCs of making Barrett's metaplasia

Barrett's esophagus, a squamous-to-columnar cell metaplasia that develops as a result of chronic gastroesophageal reflux disease (GERD), is a risk factor for esophageal adenocarcinoma. The molecular events underlying the pathogenesis of Barrett's metaplasia are poorly understood, but recent studies suggest that interactions among developmental signaling pathways, morphogenetic factors, and Caudal homeobox (Cdx) genes play key roles. Strong expression of Cdx genes normally is found in the intestine but not in the esophagus and stomach. When mice are genetically engineered so that their gastric cells express Cdx, the stomach develops a metaplastic, intestinal-type epithelium similar to that of Barrett's esophagus. Exposure to acid and bile has been shown to activate the Cdx promoter in certain esophageal cell lines, and Cdx expression has been found in inflamed esophageal squamous epithelium and in the specialized intestinal metaplasia of Barrett's esophagus. Barrett's metaplasia must be sustained by stem cells, which might be identified by putative, intestinal stem cell markers like leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) and doublecortin and CaM kinase-like-1 (DCAMKL-1). Emerging concepts in tumor biology suggest that Barrett's cancers may develop from growth-promoting mutations in metaplastic stem cells or their progenitor cell progeny. This report reviews the roles of developmental signaling pathways and the Cdx genes in the development of normal gut epithelia and the potential mechanisms whereby GERD may induce the esophageal expression of Cdx genes and other morphogenetic factors that mediate the development of Barrett's metaplasia. The role of stem cells in the development of metaplasia and in carcinogenesis and the potential for therapies directed at those stem cells also is addressed.

Multilayered epithelium in a rat model and human Barrett's esophagus: similar expression patterns of transcription factors and differentiation markers

Background

In rats, esophagogastroduodenal anastomosis (EGDA) without concomitant chemical carcinogen treatment leads to gastroesophageal reflux disease, multilayered epithelium (MLE, a presumed precursor in intestinal metaplasia), columnar-lined esophagus, dysplasia, and esophageal adenocarcinoma. Previously we have shown that columnar-lined esophagus in EGDA rats resembled human Barrett's esophagus (BE) in its morphology, mucin features and expression of differentiation markers (Lab. Invest. 2004;84:753–765). The purpose of this study was to compare the phenotype of rat MLE with human MLE, in order to gain insight into the nature of MLE and its potential role in the development of BE.

Methods

Serial sectioning was performed on tissue samples from 32 EGDA rats and 13 patients with established BE. Tissue sections were immunohistochemically stained for a variety of transcription factors and differentiation markers of esophageal squamous epithelium and intestinal columnar epithelium.

Results

We detected MLE in 56.3% (18/32) of EGDA rats, and in all human samples. As expected, both rat and human squamous epithelium, but not intestinal metaplasia, expressed squamous transcription factors and differentiation markers (p63, Sox2, CK14 and CK4) in all cases. Both rat and human intestinal metaplasia, but not squamous epithelium, expressed intestinal transcription factors and differentiation markers (Cdx2, GATA4, HNF1α, villin and Muc2) in all cases. Rat MLE shared expression patterns of Sox2, CK4, Cdx2, GATA4, villin and Muc2 with human MLE. However, p63 and CK14 were expressed in a higher proportion of rat MLE compared to humans.

Conclusion

These data indicate that rat MLE shares similar properties to human MLE in its expression pattern of these markers, not withstanding small differences, and support the concept that MLE may be a transitional stage in the metaplastic conversion of squamous to columnar epithelium in BE.

Characterization of esophageal submucosal glands in pig tissue and cultures

The submucosal glands (SMGs) of the pig esophagus, like the human, secrete mucin and bicarbonate, which help in luminal acid clearance and epithelial protection. The aim of this study was to characterize histochemically the esophageal SMGs and a primary culture obtained from these glands. Tissues and cultures were stained with hematoxylin and eosin, periodic acid Schiff, Alcian blue, lectins, or cytokeratins. In the perfused esophagus, addition of carbachol increased mucin secretion by approximately 2-fold. The results indicate that [1] a method for culturing SMG cells was developed; [2] conventional staining indicates the presence of sulfated, acidic, and neutral mucopolysaccharides in glands and cultures; [3] lectin binding indicates the presence of N-acetyl glucosamine, N-acetyl neuraminic acid, N-acetyl galactosamine, and alpha-L: -fucose in mucous cells and cultures; [4] cytokeratin and lectin staining indicated similarities with Barrett epithelium (columnar metaplasia of the esophagus); and [5] cholinergic agonists enhance mucin secretion and this could play a significant role in esophageal protection.

Grading of dysplasia in Barrett's oesophagus: substantial interobserver variation between general and gastrointestinal pathologists

AIMS

To determine interobserver variation in grading of dysplasia in Barrett's oesophagus (BO) between non-expert general pathologists and expert gastrointestinal pathologists on the one hand and between expert pathologists on the other hand.

METHODS AND RESULTS

In this prospective multicentre study, non-expert and expert pathologists graded biopsy specimens of 920 patients with endoscopic BO, which were blindly reviewed by one member of a panel of expert pathologists (panel experts) and by a second panel expert in case of disagreement on dysplasia grade. Agreement between two of three pathologists was established as the final diagnosis. Analysis was performed by kappa statistics. Due to absence of intestinal metaplasia, 127/920 (14%) patients were excluded. The interobserver agreement for dysplasia [no dysplasia (ND) versus indefinite for dysplasia/low-grade dysplasia (IND/LGD) versus high-grade dysplasia (HGD)/adenocarcinoma (AC)] between non-experts and first panel experts and between initial experts and first panel experts was fair (kappa = 0.24 and kappa = 0.27, respectively), and substantial for differentiation of HGD/AC from ND/IND/LGD (kappa = 0.62 and kappa = 0.58, respectively).

CONCLUSIONS

There was considerable interobserver variability in the interpretation of ND or IND/LGD in BO between non-experts and experts, but also between expert pathologists. This suggests that less subjective markers are needed to determine the risk of developing AC in BO.

Molecular defense mechanisms of Barrett's metaplasia estimated by an integrative genomics

Barrett's esophagus is characterized by the replacement of squamous epithelium with specialized intestinal metaplastic mucosa. The exact mechanisms of initiation and development of Barrett's metaplasia remain unknown, but a hypothesis of "successful adaptation" against noxious reflux components has been proposed. To search for the repertoire of adaptation mechanisms of Barrett's metaplasia, we employed high-throughput functional genomic and proteomic methods that defined the molecular background of metaplastic mucosa resistance to reflux. Transcriptional profiling was established for 23 pairs of esophageal squamous epithelium and Barrett's metaplasia tissue samples using Affymetrix U133A 2.0 GeneChips and validated by quantitative real-time polymerase chain reaction. Differences in protein composition were assessed by electrophoretic and mass-spectrometry-based methods. Among 2,822 genes differentially expressed between Barrett's metaplasia and squamous epithelium, we observed significantly overexpressed metaplastic mucosa genes that encode cytokines and growth factors, constituents of extracellular matrix, basement membrane and tight junctions, and proteins involved in prostaglandin and phosphoinositol metabolism, nitric oxide production, and bioenergetics. Their expression likely reflects defense and repair responses of metaplastic mucosa, whereas overexpression of genes encoding heat shock proteins and several protein kinases in squamous epithelium may reflect lower resistance of normal esophageal epithelium than Barrett's metaplasia to reflux components. Despite the methodological and interpretative difficulties in data analyses discussed in this paper, our studies confirm that Barrett's metaplasia may be regarded as a specific microevolution allowing for accumulation of mucosal morphological and physiological changes that better protect against reflux injury.

Does CDX2 expression predict Barrett's metaplasia in oesophageal columnar epithelium without goblet cells?

BACKGROUND

Intestinal metaplasia (Barrett's oesophagus), but not cardiac-type mucosa in columnar-lined oesophagus, is regarded as premalignant. As intestinal metaplasia and cardiac-type mucosa are endoscopically indiscernible, it is difficult to take targeted samples from columnar-lined oesophagus with consequently a risk of having undetected intestinal metaplasia.

AIM

To investigate whether the intestinal markers CDX2, MUC2 and villin can predict the presence of undetected intestinal metaplasia in columnar-lined oesophagus. Methods Presence of intestinal metaplasia or cardiac-type mucosa was identified in 122 biopsy sets of columnar-lined oesophagus from 61 patients, collected at two subsequent follow-up upper endoscopies. CDX2, MUC2 and villin expression were determined by immunohistochemistry.

RESULTS

All intestinal metaplasia samples (55) were positive for CDX2 and MUC2 and 32 of 55 for villin. CDX2 expression was detected in 23 of 67 (34%) samples with only cardiac-type mucosa. Detection of CDX2 in cardiac-type mucosa increased the likelihood of finding intestinal metaplasia in another biopsy set of columnar-lined oesophagus (odds ratio 3.5, 95% CI = 1.2-10, P = 0.02). MUC2 was positive in 13 of 23 (57%) of CDX2-positive cardiac-type mucosa samples, whereas villin was detected in seven of 23 (30%).

CONCLUSIONS

CDX2 expression in cardiac-type mucosa might be able to predict the presence of undetected intestinal metaplasia in columnar-lined oesophagus, and thus may be a putative marker for the presence of intestinal metaplasia in the absence of goblet cells.

hERG1 channels in human esophagus: evidence for their aberrant expression in the malignant progression of Barrett's esophagus

Ion channels regulate a broad range of cellular activities. Alteration in ion channel function has been reported in different human pathologies, such as cardiac, neuromuscular, autoimmune diseases, and cancer. We investigated the expression of hERG1 K+ channels in the human upper gastrointestinal tract, focusing our attention on the lower esophagus. In particular, we analyzed by both Reverse transcription and polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC) endoscopic samples obtained from normal subjects, from patients suffering from gastroesophageal reflux, associated or not with esophagitis, and from patients affected by Barrett's esophagus (BE), that is, intestinal metaplasia. None of the normal samples, nor those from patients with gastro-esophageal reflux symptoms and reflux esophagitis expressed the hERG1 protein. On the other hand, 69% of patients with BE expressed hERG1. Since BE is a preneoplastic lesion, dysplasias (Ds) and adenocarcinomas (ADKs) arising on a previously diagnosed BE were also analyzed, and all the samples showed a high expression of the hERG1 protein. The surveillance of patients with BE showed that 89% of those who later developed ADKs displayed hERG1 expression. Data here reported, support the hypothesis that hERG1 expression marks an early step of the progression of normality to cancer in the human esophagus through a metaplastic and dysplastic stage.

Immunohistochemical evaluation of pRb2/p130, VEGF, EZH2, p53, p16, p21waf-1, p27, and PCNA in Barrett's esophagus

Control of the G1/S-phase transition as well as angiogenic switch are two of the most studied mechanisms in cancer. The current study examined the correlation between the immunohistochemical expression of pRb2/p130, VEGF, EZH2, p53, p16, p21waf-1, p27, and PCNA in Barrett's esophagus (BE). Overall, p53 showed a much higher expression in BE patients (up to 50%) than in controls (1-10%) (P < 0.005). Also p21 showed a downregulation in BE when compared to normal esophagus (70% of cells vs. 65%), but the difference did not show any statistical significance (P = 0.45). pRb2/p130 was detected in 80% of cells in normal controls, but showed positive in only 20% of cells in BE biopsies. Additionally, Rb2/p130 expression was inversely correlated to that of VEGF, EZH2, and PCNA (P < 0.0001, P = 0.0032, P < 0.001, respectively). p27 stained more intensely and in a widespread manner (70%) cells in normal esophageal tissues but about only 30% in BE samples (P < 0.001). Lastly, in accordance with other reports, we also found p16 expressed by immunohistochemistry at high levels in normal controls and at low levels in BE (P < 0.001). In conclusion, p16, p21, p27, and p53 staining confirmed previously published data. Interestingly, pRb2/p130 expression was found significantly decreased in metaplastic epithelium compared to normal controls and showed significant inverse correlation with the expression of other markers, such as VEGF, EZH2, and PCNA. These data, taken together, indicate that these molecular events occurring in Barrett's metaplasia (BM) may represent one of the many steps taking place during esophageal malignant progression such as impairment of cell-cycle control, altered differentiation, and unbalanced angiogenesis.

p53 and the malignant progression of Barrett's esophagus

Barrett's esophagus (BE) is a metaplastic disorder in which specialized columnar epithelium replaces healthy squamous epithelium (intestinal metaplasia). Even though its pathophysiology and the steps of its neoplastic progression are not completely understood, BE can be considered as a complication of gastroesophageal reflux disease (GERD). Given that esophageal adenocarcinoma, which is continually increasing in the Western world, still has a poor prognosis and suffers from late diagnosis, and because BE is a precancerous lesion, there is a strong need for good molecular markers of malignant progression in Barrett's metaplasia (BM). The aim of this review is to examine the published data regarding the role that assessment of p53 may play in the management of BE, trying to understand if it may be a useful marker to early diagnose BE malignant transformation.