Intestinal differentiation in metaplastic, nongoblet columnar epithelium in the esophagus. Am J Surg Pathol. 2009;33:1006-1015. [PMID: 19363439 DOI: 10.1097/pas.0b013e31819f57e9]

Pathophysiology of gastro-oesophageal reflux disease: implications for diagnosis and management

Gastro-oesophageal reflux disease (GERD) is a common gastrointestinal disorder in which retrograde flow of gastric content into the oesophagus causes uncomfortable symptoms and/or complications. It has a multifactorial and partially understood pathophysiology. GERD starts in the stomach, where the refluxate material is produced. Following the trajectory of reflux, the failure of the antireflux barrier, primarily the lower oesophageal sphincter and the crural diaphragm, enables the refluxate to reach the oesophageal lumen, triggering oesophageal or extra-oesophageal symptoms. Reflux clearance mechanisms such as primary and secondary peristalsis and the arrival of bicarbonate-rich saliva are critical to prevent mucosal damage. Alterations of the oesophageal mucosal integrity, such as macroscopic oesophagitis or microscopic changes, determine the perception of symptoms. The intensity of the symptoms is affected by peripheral and central neural and psychological mechanisms. In this Review, we describe an updated understanding of the complex and multifactorial pathophysiology of GERD. It is now recognized that different GERD phenotypes have different degrees of reflux, severity of mucosal integrity damage and type, and severity of symptoms. These variations are probably due to the occurrence of a predominant pathophysiological mechanism in each patient. We also describe the main pathophysiological mechanisms of GERD and their implications for personalized diagnosis and management.

3'-sulfated LewisA/C: An oncofetal epitope associated with metaplastic and oncogenic plasticity of the gastrointestinal foregut

Metaplasia, dysplasia, and cancer arise from normal epithelia via a plastic cellular transformation, typically in the setting of chronic inflammation. Such transformations are the focus of numerous studies that strive to identify the changes in RNA/Protein expression that drive such plasticity along with the contributions from the mesenchyme and immune cells. However, despite being widely utilized clinically as biomarkers for such transitions, the role of glycosylation epitopes is understudied in this context. Here, we explore 3'-Sulfo-Lewis A/C, a clinically validated biomarker for high-risk metaplasia and cancer throughout the gastrointestinal foregut: esophagus, stomach, and pancreas. We discuss the clinical correlation of sulfomucin expression with metaplastic and oncogenic transformation, as well as its synthesis, intracellular and extracellular receptors and suggest potential roles for 3'-Sulfo-Lewis A/C in contributing to and maintaining these malignant cellular transformations.

Mechanisms and pathophysiology of Barrett oesophagus

Barrett oesophagus, in which a metaplastic columnar mucosa that can predispose individuals to cancer development lines a portion of the distal oesophagus, is the only known precursor of oesophageal adenocarcinoma, the incidence of which has increased profoundly over the past several decades. Most evidence suggests that Barrett oesophagus develops from progenitor cells at the oesophagogastric junction that proliferate and undergo epithelial-mesenchymal transition as part of a wound-healing process that replaces oesophageal squamous epithelium damaged by gastroesophageal reflux disease (GERD). GERD also seems to induce reprogramming of key transcription factors in the progenitor cells, resulting in the development of the specialized intestinal metaplasia that is characteristic of Barrett oesophagus, probably through an intermediate step of metaplasia to cardiac mucosa. Genome-wide association studies suggest that patients with GERD who develop Barrett oesophagus might have an inherited predisposition to oesophageal metaplasia and that there is a shared genetic susceptibility to Barrett oesophagus and to several of its risk factors (such as GERD, obesity and cigarette smoking). In this Review, we discuss the mechanisms, pathophysiology, genetic predisposition and cells of origin of Barrett oesophagus, and opine on the clinical implications and future research directions.

Kyoto international consensus report on anatomy, pathophysiology and clinical significance of the gastro-oesophageal junction

OBJECTIVE

An international meeting was organised to develop consensus on (1) the landmarks to define the gastro-oesophageal junction (GOJ), (2) the occurrence and pathophysiological significance of the cardiac gland, (3) the definition of the gastro-oesophageal junctional zone (GOJZ) and (4) the causes of inflammation, metaplasia and neoplasia occurring in the GOJZ.

DESIGN

Clinical questions relevant to the afore-mentioned major issues were drafted for which expert panels formulated relevant statements and textural explanations.A Delphi method using an anonymous system was employed to develop the consensus, the level of which was predefined as ≥80% of agreement. Two rounds of voting and amendments were completed before the meeting at which clinical questions and consensus were finalised.

RESULTS

Twenty eight clinical questions and statements were finalised after extensive amendments. Critical consensus was achieved: (1) definition for the GOJ, (2) definition of the GOJZ spanning 1 cm proximal and distal to the GOJ as defined by the end of palisade vessels was accepted based on the anatomical distribution of cardiac type gland, (3) chemical and bacterial (Helicobacter pylori) factors as the primary causes of inflammation, metaplasia and neoplasia occurring in the GOJZ, (4) a new definition of Barrett's oesophagus (BO).

CONCLUSIONS

This international consensus on the new definitions of BO, GOJ and the GOJZ will be instrumental in future studies aiming to resolve many issues on this important anatomic area and hopefully will lead to better classification and management of the diseases surrounding the GOJ.

mAb Das-1 recognizes 3'-Sulfated Lewis A/C, which is aberrantly expressed during metaplastic and oncogenic transformation of several gastrointestinal Epithelia

INTRODUCTION

Multiple previous studies have shown the monoclonal antibody Das-1 (formerly called 7E12H12) is specifically reactive towards metaplastic and carcinomatous lesions in multiple organs of the gastrointestinal system (e.g. Barrett's esophagus, intestinal-type metaplasia of the stomach, gastric adenocarcinoma, high-grade pancreatic intraepithelial neoplasm, and pancreatic ductal adenocarcinoma) as well as in other organs (bladder and lung carcinomas). Beyond being a useful biomarker in tissue, mAb Das-1 has recently proven to be more accurate than current paradigms for identifying cysts harboring advanced neoplasia. Though this antibody has been used extensively for clinical, basic science, and translational applications for decades, its epitope has remained elusive.

METHODS

In this study, we chemically deglycosylated a standard source of antigen, which resulted in near complete loss of the signal as measured by western blot analysis. The epitope recognized by mAb Das-1 was determined by affinity to a comprehensive glycan array and validated by inhibition of a direct ELISA.

RESULTS

The epitope recognized by mAb Das-1 is 3'-Sulfo-Lewis A/C (3'-Sulfo-LeA/C). 3'-Sulfo-LeA/C is broadly reexpressed across numerous GI epithelia and elsewhere during metaplastic and carcinomatous transformation.

DISCUSSION

3'-Sulfo-LeA/C is a clinically important antigen that can be detected both intracellularly in tissue using immunohistochemistry and extracellularly in cyst fluid and serum by ELISA. The results open new avenues for tumorigenic risk stratification of various gastrointestinal lesions.

Barrett's esophagus: The pathomorphological and molecular genetic keystones of neoplastic progression

Barrett's esophagus is a widespread chronically progressing disease of heterogeneous nature. A life threatening complication of this condition is neoplastic transformation, which is often overlooked due to lack of standardized approaches in diagnosis, preventative measures and treatment. In this essay, we aim to stratify existing data to show specific associations between neoplastic transformation and the underlying processes which predate cancerous transition. We discuss pathomorphological, genetic, epigenetic, molecular and immunohistochemical methods related to neoplasia detection on the basis of Barrett's esophagus. Our review sheds light on pathways of such neoplastic progression in the distal esophagus, providing valuable insight into progression assessment, preventative targets and treatment modalities. Our results suggest that molecular, genetic and epigenetic alterations in the esophagus arise earlier than cancerous transformation, meaning the discussed targets can help form preventative strategies in at-risk patient groups.

Vil-Cre specific Schlafen 3 knockout mice exhibit sex-specific differences in intestinal differentiation markers and Schlafen family members expression levels

The intestinal epithelium requires self-renewal and differentiation in order to function and adapt to pathological diseases such as inflammatory bowel disease, short gut syndrome, and ulcers. The rodent Slfn3 protein and the human Slfn12 analog are known to regulate intestinal epithelial differentiation. Previous work utilizing a pan-Slfn3 knockout (KO) mouse model revealed sex-dependent gene expression disturbances in intestinal differentiation markers, metabolic pathways, Slfn family member mRNA expression, adaptive immune cell proliferation/functioning genes, and phenotypically less weight gain and sex-dependent changes in villus length and crypt depth. We have now created a Vil-Cre specific Slfn3KO (VC-Slfn3KO) mouse to further evaluate its role in intestinal differentiation. There were increases in Slfn1, Slfn2, Slfn4, and Slfn8 and decreases in Slfn5 and Slfn9 mRNA expression that were intestinal region and sex-specific. Differentiation markers, sucrase isomaltase (SI), villin 1, and dipeptidyl peptidase 4 and glucose transporters, glucose transporter 1 (Glut1), Glut2, and sodium glucose transporter 1 (SGLT1), were increased in expression in VC-Slfn3KO mice based on intestinal region and were also highly female sex-biased, except for SI in the ileum was also increased for male VC-Slfn3KO mice and SGLT1 was decreased for both sexes. Overall, the variations that we observed in these VC-Slfn3KO mice indicate a complex regulation of intestinal gene expression that is sex-dependent.

miR-24-3p regulates CDX2 during intestinalization of cardiac-type epithelium in a human model of Barrett's esophagus

BACKGROUND

Cardiac-type epithelium has been proposed as the precursor of intestinal metaplasia in the development of Barrett's esophagus. Dysregulation of microRNAs (miRNAs) and their effects on CDX2 expression may contribute to intestinalization of cardiac-type epithelium. The aim of this study was to examine the possible effect of specific miRNAs on the regulation of CDX2 in a human model of Barrett's esophagus.

METHODS

Microdissection of cardiac-type glands was performed in biopsy samples from patients who underwent esophagectomy and developed cardiac-type epithelium in the remnant esophagus. OpenArray™ analysis was used to compare the miRNAs profiling of cardiac-type glands with negative or fully positive CDX2 expression. CDX2 was validated as a miR-24 messenger RNA target by the study of CDX2 expression upon transfection of miRNA mimics and inhibitors in esophageal adenocarcinoma cell lines. The CDX2/miR-24 regulation was finally validated by in situ miRNA/CDX2/MUC2 co-expression analysis in cardiac-type mucosa samples of Barrett's esophagus.

RESULTS

CDX2 positive glands were characterized by a unique miRNA profile with a significant downregulation of miR-24-3p, miR-30a-5p, miR-133a-3p, miR-520e-3p, miR-548a-1, miR-597-5p, miR-625-3p, miR-638, miR-1255b-1, and miR-1260a, as well as upregulation of miR-590-5p. miRNA-24-3p was identified as potential regulator of CDX2 gene expression in three databases and confirmed in esophageal adenocarcinoma cell lines. Furthermore, miR-24-3p expression showed a negative correlation with the expression of CDX2 in cardiac-type mucosa samples with different stages of mucosal intestinalization.

CONCLUSION

These results showed that miRNA-24-3p regulates CDX2 expression, and the downregulation of miRNA-24-3p was associated with the acquisition of the intestinal phenotype in esophageal cardiac-type epithelium.

Barrett's Esophagus and Intestinal Metaplasia

Intestinal metaplasia refers to the replacement of the differentiated and mature normal mucosal epithelium outside the intestinal tract by the intestinal epithelium. This paper briefly describes the etiology and clinical significance of intestinal metaplasia in Barrett’s esophagus. This article summarizes the impact of intestinal metaplasia on the diagnosis, monitoring, and treatment of Barrett’s esophagus according to different guidelines. We also briefly explore the basis for the endoscopic diagnosis of intestinal metaplasia in Barrett’s esophagus. The identification techniques of goblet cells in Barrett’s esophagus are also elucidated by some scholars. Additionally, we further elaborate on the current treatment methods related to Barrett’s esophagus.

Columnar metaplasia and Barrett’s esophagus: morphological heterogeneity and immunohistochemical phenotype

Barrett’s esophagus (BE) is a pathologically confirmed intestinal metaplasia (CM) of the distal esophagus. BE is recognized as a potential complication of gastroesophageal reflux disease (GERD) and a premalignant condition with a high risk of neoplastic progression. The aim of this study was to compare the morphology of biopsied BE segments and CM segments extending < 1 cm and > 1 cm above the gastroesophageal junction (GEJ), as well as to perform the immunohistochemical analysis of biopsies with BE and CM > 1 cm above GEJ with or without dysplasia. The study recruited 92 patients with GERD: 42 patients with BE, 24 patients with CM > 1 cm above GEJ (С0М1.5–С13M14) and 26 patients with CM < 1 cm above GEJ (С0М0.3–0.8). Comparative analysis of tissue morphology revealed an association between the reactive changes in the epithelium and the severity of esophagitis in all groups. Reactive changes were detected significantly more often in BE segments than in CM segments > 1 cm (Mann-Whitney U, p < 0.05). Eight patients with BE (19.05%) were found to have low-grade dysplasia. One patient with CM > 1 cm above GEJ (4.2%) had high-grade dysplasia with cardiac-type metaplasia and immunohistochemical features of submorphological enteralization. Immunohistochemical testing for the intestinal and gastric markers of cell differentiation revealed the signs of submorphological enteralisation in all esophageal specimens with cardiac and fundic type metaplasia and in the specimens with BE in the areas lacking goblet cells.

Challenges to diagnostic standardization of Barrett's esophagus in Asia

Barrett's esophagus (BE), a premalignant condition of the lower esophagus, is increasingly prevalent in Asia. However, endoscopic and histopathological criteria vary widely between studies across Asia, making it challenging to assess comparability between geographical regions. Furthermore, guidelines from various societies worldwide provide differing viewpoints and definitions, leading to diagnostic challenges that affect prognostication of the condition. In this review, the authors discuss the controversies surrounding the diagnosis of BE, particularly in Asia. Differences between guidelines worldwide are summarized with further discussion regarding various classifications of BE used, different definitions of gastroesophageal junction used across geographical regions and the clinical implications of intestinal metaplasia in the setting of BE. Although many guidelines recommend the Seattle protocol as the preferred approach regarding dysplasia surveillance in BE, some limitations exist, leading to poor adherence. Newer technologies, such as acetic acid-enhanced magnification endoscopy, narrow band imaging, Raman spectroscopy, molecular approaches and the use of artificial intelligence appear promising in addressing these problems, but further studies are required before implementation into routine clinical practice. The Asian Barrett's Consortium also outlines its ongoing plans to tackle the challenge of standardizing the diagnosis of BE in Asia.

Pathogenesis and Cells of Origin of Barrett's Esophagus

In patients with Barrett's esophagus (BE), metaplastic columnar mucosa containing epithelial cells with gastric and intestinal features replaces esophageal squamous mucosa damaged by gastroesophageal reflux disease. This condition is estimated to affect 5.6% of adults in the United States, and is a major risk factor for esophageal adenocarcinoma. Despite the prevalence and importance of BE, its pathogenesis is incompletely understood and there are disagreements over the cells of origin. We review mechanisms of BE pathogenesis, including transdifferentiation and transcommitment, and discuss potential cells of origin, including basal cells of the squamous epithelium, cells of esophageal submucosal glands and their ducts, cells of the proximal stomach, and specialized populations of cells at the esophagogastric junction (residual embryonic cells and transitional basal cells). We discuss the concept of metaplasia as a wound-healing response, and how cardiac mucosa might be the precursor of the intestinal metaplasia of BE. Finally, we discuss shortcomings in current diagnostic criteria for BE that have important clinical implications.

Barretts's carcinogenesis

Barrett's esophagus is considered a precancerous lesion of esophageal adenocarcinoma (EAC). Long‐segment Barrett's esophagus, which is generally associated with intestinal metaplasia, has a higher rate of carcinogenesis than short‐segment Barrett's esophagus, which is mainly composed of cardiac‐type mucosa. However, a large number of cases reportedly develop EAC from the cardiac‐type mucosa which has the potential to involve intestinal phenotypes. There is no consensus regarding whether the definition of Barrett's epithelium should include intestinal metaplasia. Basic researches using rodent models have provided information regarding the origins of Barrett's epithelium. Nevertheless, it remains unclear whether differentiated gastric columnar epithelium or stratified esophageal squamous epithelium undergo transdifferentiation into the intestinal‐type columnar epithelium, transcommittment into the columnar epithelium, or whether the other pathways exist. Reflux of duodenal fluid including bile acids into the stomach may occur when an individual lies down after eating, which could cause the digestive juices to collect in the fornix of the stomach. N‐nitroso‐bile acids are produced with nitrites that are secreted from the salivary glands, and bile acids can drive expression of pro‐inflammatory cytokines via EGFR or the NF‐κB pathway. These steps may contribute significantly to carcinogenesis.

Definition of Barrett Esophagus in the United States: Support for Retention of a Requirement for Goblet Cells

Barrett esophagus (BE) predisposes patients to the development of esophageal adenocarcinoma (EAC). However, the global definition of BE is controversial. Pathologists in Europe and the United States require intestinal metaplasia (IM) within columnar-lined mucosa (CLM) in the tubular esophagus to diagnose BE, whereas in the UK and Japan only the presence of CLM is required. To aid in establishing an appropriate definition for BE, we evaluated whether IM accompanies EAC in a US patient cohort. We examined a series of 139 consecutive patients who underwent endoscopic mucosal resections or esophagectomies for EAC performed at a US tertiary care center. The resection specimens were evaluated for the presence (IM+) or absence (IM-) of IM within CLM. Ninety-seven (70%) patients were IM+. Tumors found in IM- patients tended to be advanced at the time of resection (57% pT3 or greater, IM-; 31% pT3 or greater, IM+; P=0.02) such that the tumor may have "overgrown" zones of IM. We hypothesized that changes as a result of neoadjuvant chemotherapy or radiation might mask preexisting IM. When evaluating this hypothesis, we found that 34 of 39 of treatment-naive patients were IM+. Two of the 5 IM- patients had prior IM+ biopsies resulting in 92% of treatment-naive patients who were IM+. In our US hospital population, CLM with IM in the tubular esophagus is found in association with EAC in 70% to 92% of patients. We believe that based on these data the United States definition of BE should continue to require the presence of IM.

Some observations on Barrett esophagus and associated dysplasia

Biopsy samples from esophageal columnar metaplasia and dysplasia are commonly encountered in Western pathology practice and knowing a few pitfalls can save both pathologists and patients a great deal of anxiety. Herein we discuss criteria for Barrett esophagus, evaluation of dysplasia, and some pitfalls in reviewing endoscopic mucosal resections. Also included is a summary of suggested follow-up for patients with Barrett esophagus.

Histology of Barrett's Metaplasia: Do Goblet Cells Matter?

This review has provided a summary of the biology of goblet cell metaplasia in CLE as it pertains to BE. Goblet cells are terminally differentiated nonproliferative cells that have many overlapping histochemical characteristics with mucinous columnar cells and pseudogoblet cells. There is an abundance of evidence that suggests that use of goblet cells as a biomarker of BE, and its progression to malignancy, is problematic. Some of these limitations include the fact that the background non-goblet epithelium in most patients with CLE is biologically intestinalized and contains molecular abnormalities similar to goblet cell CLE, goblet cells fluctuate with time and decrease in number with progression of neoplasia, and pathologists have problems with interpretation, and distinction, of goblet cells from other types of cells in the esophagus. Sampling error results in sensitivity and specificity issues that limit its positive predictive value. Goblet cells are fewest in number in the same population of patients with CLE that are hardest to detect endoscopically (i.e., those with short or ultrashort CLE). Nevertheless, the risk of cancer in patients with short-segment BE, a condition difficult to distinguish from the stomach, is very low regardless of the presence or absence of goblet cells so it is unclear what the role of goblet cells is in these patients as a biomarker. Nevertheless, if the answer to the following question, "Would you as a gastroenterologist recommend surveillance for a patient with clear endoscopic evidence of CLE, particularly if it is ≥ 3 cm in length, but in which goblet cells were not reported to be present by the pathologist," is yes, then the US requirement for goblet cells as part of the criteria for "BE" is superfluous.

Cardiac Metaplasia: Follow, Treat, or Ignore?

Over the past two decades, evidence has accumulated to challenge the traditional view that cardiac mucosa, which is comprised exclusively of mucus glands, is the normal lining of the most proximal portion of the stomach (the gastric cardia). There is now considerable evidence to suggest that cardiac mucosa develops as a GERD-induced, squamous-to-columnar esophageal metaplasia in some, if not all, cases. Although cardiac mucosa lacks the goblet cells commonly required for a histologic diagnosis of intestinal metaplasia, cardiac mucosa has many molecular features of an intestinal-type mucosa, and appears to be the precursor of intestinal metaplasia with goblet cells. In apparently normal individuals, cardiac mucosa is commonly found in a narrow band, less than 3 mm in extent, on the columnar side of the squamo-columnar junction at the end of the esophagus. A greater extent of cardiac mucosa can be found in GERD patients, and the magnitude of that extent appears to be an index of GERD severity. Presently, the risk of adenocarcinoma imposed by cardiac mucosa is not clear, but appears to be far less than that of intestinal metaplasis with goblet cells. The British Society of Gastroenterology accepts an esophagus lined by cardiac mucosa as a "Barrett's esophagus". However, if one defines Barrett's esophagus as a metaplasia that predisposes to cancer, then only intestinal metaplasia clearly fulfills that criterion at this time. Well-designed, prospective studies are needed to establish the malignant potential of cardiac mucosa.

Origins of Metaplasia in the Esophagus: Is This a GE Junction Stem Cell Disease?

The incidence of esophageal adenocarcinoma (EAC) and its precursor lesion Barrett's esophagus (BE) has been increasing steadily in the western world in recent decades. Understanding the cellular origins of BE and the conditions responsible for their malignant transformation would greatly facilitate risk assessment and identification of patients at risk of progression, but this topic remains a source of debate. Here, we review recent findings that have provided support for the gastroesophageal junction (GEJ) as the main source of stem cells that give rise to BE and EAC. These include both gastric cardia cells and transitional basal cells. Furthermore, we discuss the role of chronic injury and inflammation in a tumor microenvironment as a major factor in promoting stem cell expansion and proliferation as well as transformation of the GEJ-derived stem cells and progression to EAC. We conclude that there exists a large amount of empirical support for the GEJ as the likely source of BE stem cells. While BE seems to resemble a successful adaptation to esophageal damage, carcinogenesis appears as a consequence of natural selection at the level of GEJ stem cells, and later glands, that expand into the esophagus wherein the local ecology creates the selective landscape for cancer progression.

The metaplastic mosaic of Barrett's oesophagus

Barrett's oesophagus surveillance biopsies represent a significant share of the daily workload for a busy histopathology department. Given the emphasis on endoscopic detection and dysplasia grading, it is easy to forget that the benefits of these screening programs remain unproven. The majority of patients are at low risk of progression to oesophageal adenocarcinoma, and periodic surveillance of these patients is burdensome and costly. Here, we investigate the parallels in the development of Barrett's oesophagus and other scenarios of wound healing in the intestine. There is now increased recognition of the full range of glandular phenotypes that can be found in patients' surveillance biopsies, and emerging evidence suggests parallel pathways to oesophageal adenocarcinoma. Greater understanding of the conditions that favour progression to cancer in the distal oesophagus will allow us to focus resources on patients at increased risk.

Insights Into the Pathophysiology of Esophageal Adenocarcinoma

Although researchers have identified genetic alterations that contribute to development of esophageal adenocarcinoma, we know little about features of patients or environmental factors that mediate progression of chronic acid biliary reflux to Barrett's esophagus and cancer. Increasing our understanding of the mechanisms by which normal squamous epithelium progresses to early-stage invasive cancer will help formulate rational surveillance guidelines and allow us to divest resources away from patients at low risk of malignancy. We review the cellular and genetic alterations that occur during progression of Barrett's esophagus, based on findings from clinical studies and mouse models of disease. We review the features of the luminal and mucosal microenvironment of Barrett's esophagus that promote, in a small proportion of patients, development of esophageal adenocarcinoma. Markers of clonal evolution can be used to determine patient risk for cancer and set surveillance intervals.

Histologic Features Associated With Columnar-lined Esophagus in Distal Esophageal and Gastroesophageal Junction (GEJ) Biopsies From GERD Patients: A Community-based Population Study

There are inherent problems with the endoscopic and pathologic criteria for columnar-lined esophagus (CLE). Furthermore, the clinical and biological significance of an irregular squamocolumnar junction (SCJ) is unclear. The aim of this study was to evaluate the association between histologic features in SCJ biopsies and CLE and to gain insight into the significance of an irregular SCJ. The study was a cross-sectional analysis of 2176 mucosal biopsies of the SCJ from 544 patients in a large prospective community clinic-based study of gastroesophageal reflux disease in Washington State. Biopsy samples were evaluated blindly for a wide variety of histologic features, such as the presence and type of mucosal glands, submucosal glands and ducts, goblet cells, multilayered epithelium (ME), inflammation, and buried columnar epithelium. Histologic findings were correlated with the endoscopic findings (normal Z-line, irregular Z-line, or CLE) and evaluated by logistic regression and receiver operating characteristic analysis.Five histologic features were associated with CLE: pure mucous glands, ME, presence of goblet cells, ≥50% of crypts with goblet cells, and buried columnar epithelium. Pure oxyntic glands were inversely associated with CLE. The features most strongly related to CLE included biopsies with ≥50% of crypts with goblet cells, ME, and mucosal gland type (area under the curve=0.71; 95% confidence interval=0.66-0.76). Patients with an irregular Z-line were histologically similar to those with CLE. Certain histologic features in biopsies of the SCJ are associated with the presence of CLE. Irregularity of the Z-line is probably indicative of ultrashort segment CLE, instead of being a potential variation of normal.

Lactobacillus rhamnosus GG supernatant enhance neonatal resistance to systemic Escherichia coli K1 infection by accelerating development of intestinal defense

The objective of this study was to determine whether Lactobacillus rhamnosus GG culture supernatant (LCS) has a preventive effect against gut-derived systemic neonatal Escherichia coli (E. coli) K1 infection. The preventive effects were evaluated in human colonic carcinoma cell line Caco-2 and neonatal rat models. Our in vitro results showed that LCS could block adhesion, invasion and translocation of E. coli K1 to Caco-2 monolayer via up-regulating mucin production and maintaining intestinal integrity. In vivo experiments revealed that pre-treatment with LCS significantly decrease susceptibility of neonatal rats to oral E. coli K1 infection as reflected by reduced bacterial intestinal colonization, translocation, dissemination and systemic infections. Further, we found that LCS treated neonatal rats have higher intestinal expressions of Ki67, MUC2, ZO-1, IgA, mucin and lower barrier permeability than those in untreated rats. These results indicated that LCS could enhance neonatal resistance to systemic E. coli K1 infection via promoting maturation of neonatal intestinal defense. In conclusions, our findings suggested that LCS has a prophylactic effect against systemic E. coli K1 infection in neonates. Future studies aimed at identifying the specific active ingredients in LCS will be helpful in developing effective pharmacological strategies for preventing neonatal E. coli K1 infection.

Review: Surveillance of patients with Barrett oesophagus

There has been a rapid increase in the incidence of oesophageal adenocarcinoma in most Western countries over the past thirty years. Barrett's oesophagus (BE) is a common premalignant lesion of oesophageal adenocarcinoma, although the risk of developing cancer in BE remains low. Therefore, screening is not recommended in the general population. Surveillance of BE is recommended to detect high grade dysplasia or carcinoma in an early stage, although there is no clear evidence that surveillance leads to a reduced mortality. This review discusses the several screening and surveillance techniques, including chromoendoscopy, narrow band imaging, autofluorescence imaging and confocal laser endomicroscopy, pointing out the areas that are well established as well as the new techniques that require more research.

Dynamics of SOX2 and CDX2 Expression in Barrett's Mucosa

Barrett's esophagus (BE) is the replacement of the normal esophageal squamous epithelium by a columnar lining epithelium. It is a premalignant condition for the development of adenocarcinoma of the esophagus and esophagogastric junction. BE is associated with gastroesophageal reflux which might change the expression profile of key transcription factors involved in the establishment of tissue differentiation, namely, SOX2 (associated with esophageal and gastric differentiation) and CDX2 (associated with intestinal differentiation). Here, we sought to characterize the expression profile of SOX2 and CDX2 in the sequential alterations of the esophageal mucosa towards adenocarcinoma and compare it with the well-established gastric and intestinal mucin profiles (MUC5AC, MUC6, and MUC2). We observed that SOX2 and CDX2 expression correlates with gastric and intestinal differentiation in BE, defined by morphological parameters and mucin expression. We show the presence of a complete intestinal profile in BE, without gastric mucins and without SOX2, and we observed an evolutionary modulation of the metaplastic phenotype by SOX2 and CDX2. We observed that adenocarcinomas harbor more frequently a mixed gastric and intestinal phenotype. In conclusion, our study establishes a role for transcription factors SOX2 and CDX2 in the progression from gastric to gastrointestinal differentiation in Barrett's metaplasia.

Barrett's Esophagus: A Comprehensive and Contemporary Review for Pathologists

This review provides a summary of our current understanding of, and the controversies surrounding, the diagnosis, pathogenesis, histopathology, and molecular biology of Barrett's esophagus (BE) and associated neoplasia. BE is defined as columnar metaplasia of the esophagus. There is worldwide controversy regarding the diagnostic criteria of BE, mainly with regard to the requirement to histologically identify goblet cells in biopsies. Patients with BE are at increased risk for adenocarcinoma, which develops in a metaplasia-dysplasia-carcinoma sequence. Surveillance of patients with BE relies heavily on the presence and grade of dysplasia. However, there are significant pathologic limitations and diagnostic variability in evaluating dysplasia, particularly with regard to the more recently recognized unconventional variants. Identification of non-morphology-based biomarkers may help risk stratification of BE patients, and this is a subject of ongoing research. Because of recent achievements in endoscopic therapy, there has been a major shift in the treatment of BE patients with dysplasia or intramucosal cancer away from esophagectomy and toward endoscopic mucosal resection and ablation. The pathologic issues related to treatment and its complications are also discussed in this review article.

Rates and predictors of progression to esophageal carcinoma in a large population-based Barrett's esophagus cohort

BACKGROUND AND AIMS

Rates of progression to esophageal adenocarcinoma in subjects with Barrett's esophagus (BE) are lower than previously estimated. Identification of predictors of progression will enable risk stratification of BE subjects, potentially making current surveillance programs more efficient. We aimed to assess the potential of demographic and lifestyle factors, obesity, and medications in predicting progression in BE.

METHODS

BE subjects were identified from the General Practice Research Database using validated diagnostic codes. BE subjects developing esophageal cancer (EC) 12 months after their index BE diagnosis were defined as progressors. Time-to-event analysis was used to assess the overall risk of progression to EC. Cox proportional hazards models and time-varying marginal structural models were used to assess predictors of progression.

RESULTS

Included in the analysis were 9660 BE patients. The mean age (SD) of the study subjects was 63 (13.5) years; 62.6% were men. One hundred three subjects (1.1%) progressed to EC. The mean (SD) follow-up since initial diagnosis was 4.8 (3.3) years. The incidence of EC was 2.23 per 1000 person-years of follow-up. Increasing age, male gender, and being overweight (body mass index, 25-29.9) were found to be independent predictors of progression. When time-varying models were used, proton pump inhibitor (PPI) and statin use were protective against progression.

CONCLUSIONS

In this large population-based cohort of patients with BE, increasing age, male gender, and being overweight predicted progression to EC, whereas PPI and statin use were protective against EC development. These factors may aid in developing a risk score to predict the risk of progression and chemopreventive strategies in patients with BE.

Evolution of oesophageal adenocarcinoma from metaplastic columnar epithelium without goblet cells in Barrett's oesophagus

OBJECTIVE

Barrett's oesophagus commonly presents as a patchwork of columnar metaplasia with and without goblet cells in the distal oesophagus. The presence of metaplastic columnar epithelium with goblet cells on oesophageal biopsy is a marker of cancer progression risk, but it is unclear whether clonal expansion and progression in Barrett's oesophagus is exclusive to columnar epithelium with goblet cells.

DESIGN

We developed a novel method to trace the clonal ancestry of an oesophageal adenocarcinoma across an entire Barrett's segment. Clonal expansions in Barrett's mucosa were identified using cytochrome c oxidase enzyme histochemistry. Somatic mutations were identified through mitochondrial DNA sequencing and single gland whole exome sequencing.

RESULTS

By tracing the clonal origin of an oesophageal adenocarcinoma across an entire Barrett's segment through a combination of histopathological spatial mapping and clonal ordering, we find that this cancer developed from a premalignant clonal expansion in non-dysplastic ('cardia-type') columnar metaplasia without goblet cells.

CONCLUSION

Our data demonstrate the premalignant potential of metaplastic columnar epithelium without goblet cells in the context of Barrett's oesophagus.

Localization of specialized intestinal metaplasia and the molecular alterations in Barrett esophagus in a Japanese population: an analysis of biopsy samples based on the "Seattle" biopsy protocol

It remains unclear why Barrett esophagus (BE)-associated adenocarcinoma (EAC) frequently occurs in the 0 to 3 o'clock area of the BE. The aims of this study were to clarify the localization of specialized intestinal metaplasia (SIM) as a precancerous lesion and of molecular alterations among different locations using 4-quadrant biopsies based on the "Seattle" protocol. We prospectively evaluated microsatellite instability; methylation status at the APC, CDKN2A, hMLH1, RUNX3, and MGMT genes; the immunoreactivity of the monoclonal antibody Das-1 for the colonic phenotype; and Ki-67 staining in 10 early EACs and 128 biopsy samples from 32 BE patients. Among the molecular changes, only APC gene hypermethylation was an independent predictive marker of EAC (odds ratio, 24.4; P = .01). SIM was more frequently identified in the 0 to 3 o'clock quadrant than in the 6 to 9 o'clock quadrant (P = .08). The Ki-67 index was higher in SIM than in the columnar-lined epithelium (CLE) without goblet cells (P < .0001) and in both SIM and CLE with Das-1 reactivity than in those without (P = .04 and P = .06, respectively). Furthermore, the index was relatively higher in the 0 to 3 o'clock quadrant than in the 6 to 9 o'clock quadrant in cases with Das-1 reactivity. RUNX3 methylation was more frequently found in SIM than in CLE (P = .04), whereas the incidence of the other biomarkers did not show a significant difference between the 0 to 3 o'clock and 6 to 9 o'clock areas, nor between SIM and CLE. SIM with Das-1 reactivity, but not molecular alterations, in the 0 to 3 o'clock quadrant may have higher proliferative activity compared to the other areas of the BE.

The Complex, Clonal, and Controversial Nature of Barrett's Esophagus

Barrett's esophagus (BO) is a preneoplastic condition described as the replacement of the stratified squamous epithelium of the distal esophagus with one that histologically presents as a diverse mixture of metaplastic glands resembling gastric or intestinal-type columnar epithelium. The clonal origins of BO are still unclear. More recently, we have begun to investigate the relationship between the various metaplastic gland phenotypes observed in BO, how they evolve, and the cancer risk they bestow. Studies have revealed that glands along the BO segment are clonal units containing a single stem cell clone that can give rise to all the differentiated epithelial cell types in glands. Clonal lineage tracing analysis has revealed that Barrett's glands are capable of bifurcation and this facilitates clonal expansion and competition. In fact, BO in some patients appears to consist of multiple, independently initiated clones that compete with each other for space and possibly resources. This chapter discusses the concepts of clonal competition and expansion in BO and sets out to query what we know about the role of gland diversity and phenotypic evolution within this complex columnar metaplasia.

Transcommitment: Paving the Way to Barrett's Metaplasia

Barrett's esophagus is the condition in which metaplastic columnar epithelium that predisposes to cancer development replaces stratified squamous epithelium in the distal esophagus. Potential sources for the cell or tissue of origin for metaplastic Barrett's epithelium are reviewed including native esophageal differentiated squamous cells, progenitor cells native to the esophagus located within the squamous epithelium or in the submucosal glands or ducts, circulating bone marrow-derived stem cells, and columnar progenitor cells from the squamocolumnar junction or the gastric cardia that proximally shift into the esophagus to fill voids left by damaged squamous epithelium. Wherever its source the original cell must undergo molecular reprogramming (i.e., either transdifferentiation or transcommitment) to give rise to specialized intestinal metaplasia. Transcription factors that specify squamous, columnar, intestinal, and mucus-secreting epithelial differentiation are discussed. An improved understanding of how esophageal columnar metaplasia forms could lead to development of effective treatment or prevention strategies for Barrett's esophagus. It could also more broadly inform upon normal tissue development and differentiation, wound healing, and stem cell biology.

Definition of Barrett's esophagus dysplasia: are we speaking the same language?

The definition of Barrett's esophagus (BE) is still a matter of debate. The diagnostic criteria adopted around the world for both BE and BE-related pre-cancerous lesions are inconsistent, particularly between Eastern and Western pathologists. From a clinical perspective, these different clinico-biological approaches may affect how the literature is interpreted, with detrimental effects on the clinical management of patients. The present review focuses on the major discrepancies in the field, covering both the non-neoplastic and the pre-cancerous lesions associated with Barrett's disease.

Inhibition of Notch signaling enhances transdifferentiation of the esophageal squamous epithelium towards a Barrett's-like metaplasia via KLF4

Barrett's esophagus (BE) is defined as an incomplete intestinal metaplasia characterized generally by the presence of columnar and goblet cells in the formerly stratified squamous epithelium of the esophagus. BE is known as a precursor for esophageal adenocarcinoma. Currently, the cell of origin for human BE has yet to be clearly identified. Therefore, we investigated the role of Notch signaling in the initiation of BE metaplasia. Affymetrix gene expression microarray revealed that BE samples express decreased levels of Notch receptors (NOTCH2 and NOTCH3) and one of the the ligands (JAG1). Furthermore, BE tissue microarray showed decreased expression of NOTCH1 and its downstream target HES1. Therefore, Notch signaling was inhibited in human esophageal epithelial cells by expression of dominant-negative-Mastermind-like (dnMAML), in concert with MYC and CDX1 overexpression. Cell transdifferentiation was then assessed by 3D organotypic culture and evaluation of BE-lineage specific gene expression. Notch inhibition promoted transdifferentiation of esophageal epithelial cells toward columnar-like cells as demonstrated by increased expression of columnar keratins (K8, K18, K19, K20) and glandular mucins (MUC2, MUC3B, MUC5B, MUC17) and decreased expression of squamous keratins (K5, K13, K14). In 3D culture, elongated cells were observed in the basal layer of the epithelium with Notch inhibition. Furthermore, we observed increased expression of KLF4, a potential driver of the changes observed by Notch inhibition. Interestingly, knockdown of KLF4 reversed the effects of Notch inhibition on BE-like metaplasia. Overall, Notch signaling inhibition promotes transdifferentiation of esophageal cells toward BE-like metaplasia in part via upregulation of KLF4. These results support a novel mechanism through which esophageal epithelial transdifferentiation promotes the evolution of BE.

High Goblet Cell Count Is Inversely Associated with Ploidy Abnormalities and Risk of Adenocarcinoma in Barrett's Esophagus

Purpose

Goblet cells may represent a potentially successful adaptive response to acid and bile by producing a thick mucous barrier that protects against cancer development in Barrett's esophagus (BE). The aim of this study was to determine the relationship between goblet cells (GC) and risk of progression to adenocarcinoma, and DNA content flow cytometric abnormalities, in BE patients.

Experimental Design

Baseline mucosal biopsies (N=2988) from 213 patients, 32 of whom developed cancer during the follow up period, enrolled in a prospective dynamic cohort of BE patients were scored in a blinded fashion, for the total number (#) of GC, mean # of GC/crypt (GC density), # of crypts with ≥ 1 GC, and the proportion of crypts with ≥1 GC, in both dysplastic and non-dysplastic epithelium separately. The relationship between these four GC parameters and DNA content flow cytometric abnormalities and adenocarcinoma outcome was compared, after adjustment for age, gender, and BE segment length.

Results

High GC parameters were inversely associated with DNA content flow cytometric abnormalities, such as aneuploidy, ploidy >2.7N, and an elevated 4N fraction > 6%, and with risk of adenocarcinoma. However, a Kaplan-Meier analysis showed that the total # of GC and the total # crypts with ≥1 GC were the only significant GC parameters (p<0.001 and 0.003, respectively).

Conclusions

The results of this study show, for the first time, an inverse relationship between high GC counts and flow cytometric abnormalities and risk of adenocarcinoma in BE. Further studies are needed to determine if GC depleted foci within esophageal columnar mucosa are more prone to neoplastic progression or whether loss of GC occurs secondary to underlying genetic abnormalities.

The changing role of the pathologist in the management of Barrett's oesophagus

Pathological specimens from columnar-lined oesophagus (CLO) comprise a considerable proportion of the workload of gastrointestinal pathologists in Western countries. There remain controversies concerning the diagnostic role of pathology. More recently, in the UK at least, the diagnosis has been regarded as primarily an endoscopic endeavour, with pathology being corroborative and only diagnostic when endoscopic features are equivocal or when there are additional features that make the endoscopic diagnosis unclear. There is also recognition that demonstration of intestinalisation or 'goblet cells' is not paramount, and should not be required for the diagnosis. There have been notable changes in the management of CLO neoplasia: pathologists are centrally involved in its management. Pathological assessment of endoscopic mucosal resection (EMR) specimens provides the most useful means of determining the management of early neoplasia and of determining indications for surgery. This represents an extraordinarily rapid change in management, in that, <10 years ago, laborious Seattle-type biopsy protocols were recommended, and high grade dysplasia was an indication for resectional surgery. Now, individual patient management is paramount: multi-professional meetings determine management after biopsy and EMR assessment. One significant change is that major resections are undertaken less often, in Western countries, for CLO neoplasia.

Expression of SOX9 and CDX2 in nongoblet columnar-lined esophagus predicts the detection of Barrett's esophagus during follow-up

The diagnosis of Barrett's esophagus in the United States requires both endoscopically evident columnar-lined esophagus and the presence of goblet cells by histology. Currently, there is no consensus on how patients with nongoblet columnar-lined esophagus should be followed. In this study, we investigated whether biomarkers can be used to predict the detection of goblet cells in follow-up biopsies. Patients with nongoblet columnar-lined esophagus were identified. In 13 of these cases, goblet cells were detected in subsequent follow-up endoscopic biopsies (Barrett's group). Additionally, 26 cases that remained negative for goblet cells in follow-up biopsies served as controls. Immunohistochemistry for CDX2, SOX9, BMP4, SHH, and MUC2 was performed on the initial biopsies and graded independently by at least two pathologists in a masked manner. CDX2 was positive in the nongoblet columnar epithelium of 7/13 cases in the Barrett's group and in 4/26 controls (sensitivity 54%, specificity of 85%, odds ratio (OR) 6.4). Strong and diffuse immunoreactivity for SOX9 was detected in 10/13 cases in the Barrett's group and in 1/26 controls (sensitivity 77%, specificity 96%, OR 83.3). Combining CDX2 and SOX9 as a panel increased sensitivity to 85%, although the specificity decreased to 85% (OR 30.3). SHH, BMP4, and MUC2 expression showed no significant difference between the Barrett's and control groups. In patients with nongoblet columnar-lined esophagus, SOX9 and CDX2 may be useful in identifying a subset of patients who have a higher risk of being diagnosed for Barrett's esophagus (developing goblet cells) and need closer follow-up.

BOB CAT: A Large-Scale Review and Delphi Consensus for Management of Barrett's Esophagus With No Dysplasia, Indefinite for, or Low-Grade Dysplasia

OBJECTIVES

Barrett's esophagus (BE) is a common premalignant lesion for which surveillance is recommended. This strategy is limited by considerable variations in clinical practice. We conducted an international, multidisciplinary, systematic search and evidence-based review of BE and provided consensus recommendations for clinical use in patients with nondysplastic, indefinite, and low-grade dysplasia (LGD).

METHODS

We defined the scope, proposed statements, and searched electronic databases, yielding 20,558 publications that were screened, selected online, and formed the evidence base. We used a Delphi consensus process, with an 80% agreement threshold, using GRADE (Grading of Recommendations Assessment, Development and Evaluation) to categorize the quality of evidence and strength of recommendations.

RESULTS

In total, 80% of respondents agreed with 55 of 127 statements in the final voting rounds. Population endoscopic screening is not recommended and screening should target only very high-risk cases of males aged over 60 years with chronic uncontrolled reflux. A new international definition of BE was agreed upon. For any degree of dysplasia, at least two specialist gastrointestinal (GI) pathologists are required. Risk factors for cancer include male gender, length of BE, and central obesity. Endoscopic resection should be used for visible, nodular areas. Surveillance is not recommended for <5 years of life expectancy. Management strategies for indefinite dysplasia (IND) and LGD were identified, including a de-escalation strategy for lower-risk patients and escalation to intervention with follow-up for higher-risk patients.

CONCLUSIONS

In this uniquely large consensus process in gastroenterology, we made key clinical recommendations for the escalation/de-escalation of BE in clinical practice. We made strong recommendations for the prioritization of future research.

CDX2 protein expression compared to alcian blue staining in the evaluation of esophageal intestinal metaplasia

AIM: To compare the sensitivity and specificity of CDX2 and alcian blue (AB) pH 2.5 staining in identifying esophageal intestinal metaplasia.

METHODS: One hundred and ninty-nine biopsies from 186 patients were retrospectively reviewed and categorized as Barrett’s esophagus (BE) (n = 108); non-Barrett’s esophagus (NBE) (n = 48); columnar blue cells (CB) and esophageal glands (EG) (n = 43). The biopsies were stained with AB and immunostained for CDX2 using a mouse monoclonal antibody from Biogenex (clone CDX2-88) and the Ventana Discovery X automated immunostainer. The positive and negative predictive value of each group was used to determine the predictive power of CDX2 and AB in diagnosing intestinal metaplasia.

RESULTS: All of the 108 BE biopsies (100%) were positive for AB and 102 of them (94.4%) were positive for CDX2. The six BE patients (5.6%) who failed to stain with CDX2 were found to have lost the focus of intestinal metaplasia upon deeper sectioning for immunostaining. Both AB and CDX2 were negative in 43 out of 48 (89.6%) NBE cases. Five NBE patients (10.4%) were falsely positive for AB due to the presence of EG and CB in these biopsies. These cases were all CDX2 negative. In addition, 5 AB negative NBE were found to be CDX2 positive. Based on these results the CDX2 immunostain had similar sensitivity but higher specificity (100% vs about 91%) than AB in detecting intestinal type metaplasia in these samples. Our data shows that CDX2 has a better PPV in detecting intestinal metaplasia as compared to AB (95.6% vs 71.5%, respectively).

CONCLUSION: CDX2 has a better positive predictive value than AB in detecting intestinal metaplasia. CDX2 may be useful when challenged by gastro-esophageal biopsies containing mimikers of BE.

Barrett's oesophagus diagnostic criteria: endoscopy and histology

This review summarizes the endoscopic and histologic features of Barrett's oesophagus(BO) as well as some of the recent advancements and controversies. BO represents metaplastic conversion of normal squamous epithelium of tubular oesophagus to columnar epithelium. The diagnosis of BO requires a combination of endoscopic and histopathologic findings. There is worldwide controversy regarding the exact definition of BO, particularly with regard to the requirement to histologically identify goblet cells in biopsies. The presence and detectability of goblet cells might vary depending on a variety of factors and is subject to sampling error. Therefore, a systematic biopsy sampling with sufficient number of biopsies is currently recommended to limit the likelihood of a false negative result for detection of goblet cells. There are both endoscopic and pathologic challenges in evaluating gastro-oesophageal junction biopsies in patients with irregular Z lines to determine the exact location of the sample (i.e., oesophagus versus stomach). Recently, several novel endoscopic techniques have been developed to improve BO detection. However, none have been validated yet in clinical practice. The surveillance of patients with BO relies on histologic evaluation of dysplasia. However, there are significant pathologic limitations and diagnostic variability in evaluating the presence and grading of BO dysplasia, particularly with regard to the more recently recognized non-intestinal types of dysplasia. All BO dysplasia samples should be reviewed by an expert gastrointestinal pathologist to confirm the diagnosis. Finally, it is important to emphasize that close interaction between gastroenterologists and pathologists is essential to ensure proper evaluation of endoscopic biopsies in order to optimize the surveillance and clinical management of patients with BO.

Current issues in Barrett's esophagus and Barrett's-related dysplasia

Surgical pathologists frequently encounter biopsies in patients with Barrett's esophagus (BE), defined as replacement of the normal stratified squamous epithelium of the distal esophagus by metaplastic columnar epithelium containing goblet cells. Thus, one of the primary roles of the pathologist is to definitively identify goblet cells, best done on routine stained sections. It has recently been questioned as to whether goblet cells should be absolutely necessary to render a diagnosis of BE, given immunohistochemical and flow cytometric similarities between columnar-lined esophagus with and without goblet cells. Once a diagnosis of BE is rendered, the pathologist must state, using a simple classification, whether the biopsy is negative for dysplasia or shows dysplasia (low-grade dysplasia or high-grade dysplasia). However, there are a number of known pitfalls in distinguishing dysplasia from reactive epithelium, and it can be similarly difficult to distinguish low-grade dysplasia from high-grade dysplasia. In addition, there are some cases in which the distinction of high-grade dysplasia from intramucosal adenocarcinoma can be challenging. All of these issues are summarized in this paper.

The Barrett's Gland in Phenotype Space

Barrett's esophagus is characterized by the erosive replacement of esophageal squamous epithelium by a range of metaplastic glandular phenotypes. These glandular phenotypes likely change over time, and their distribution varies along the Barrett's segment. Although much recent work has addressed Barrett's esophagus from the genomic viewpoint-its genotype space-the fact that the phenotype of Barrett's esophagus is nonstatic points to conversion between phenotypes and suggests that Barrett's esophagus also exists in phenotype space. Here we explore this latter concept, investigating the scope of glandular phenotypes in Barrett's esophagus and how they exist in physical and temporal space as well as their evolution and their life history. We conclude that individual Barrett's glands are clonal units; because of this important fact, we propose that it is the Barrett's gland that is the unit of selection in phenotypic and indeed neoplastic progression. Transition between metaplastic phenotypes may be governed by neutral drift akin to niche turnover in normal and dysplastic niches. In consequence, the phenotype of Barrett's glands assumes considerable importance, and we make a strong plea for the integration of the Barrett's gland in both genotype and phenotype space in future work.

GATA6 expression in Barrett's oesophagus and oesophageal adenocarcinoma

BACKGROUND

Barrett's oesophagus can progress towards oesophageal adenocarcinoma through a metaplasia-dysplasia-carcinoma sequence, but the underlying mechanisms are poorly understood. The transcription factor GATA6 is known to be involved in columnar differentiation and proliferation, and GATA6 gene amplification was recently linked with poor survival in oesophageal adenocarcinoma.

AIM

To study the expression of GATA6 during Barrett's oesophagus development and malignant transformation. To determine the prognostic value of GATA6 in oesophageal adenocarcinoma.

METHODS

Two retrospective cohorts were derived from the pathological archive of the University Medical Center Groningen. The first cohort contained 130 tissue samples of normal squamous epithelium, metaplasia, dysplasia and oesophageal adenocarcinoma. The second cohort consisted of a tissue microarray containing tissue from 92 oesophageal adenocarcinoma patients. Immunohistochemistry was used to examine GATA6 protein expression and to correlate GATA6 expression in oesophageal adenocarcinoma with overall and disease-free survival.

RESULTS

The percentage of GATA6-positive cells was low in squamous epithelium (10%) but increased progressively in Barrett's oesophagus (30%, P < 0.001) and high-grade dysplasia (82%, P = 0.005). GATA6 expression was not associated with overall or disease-free survival in oesophageal adenocarcinoma patients (P = 0.599 and P = 0.700 respectively).

CONCLUSION

GATA6 expression is progressively increased during Barrett's oesophagus development and its malignant transformation. However, no prognostic value of GATA6 expression could be found in oesophageal adenocarcinoma.