Detection by scanning electron microscopy of a distinctive esophageal surface cell at the junction of squamous and Barrett's epithelium

Signaling Pathways in the Pathogenesis of Barrett's Esophagus and Esophageal Adenocarcinoma

Barrett's esophagus (BE) is a premalignant lesion that can develop into esophageal adenocarcinoma (EAC). The development of Barrett's esophagus is caused by biliary reflux, which causes extensive mutagenesis in the stem cells of the epithelium in the distal esophagus and gastro-esophageal junction. Other possible cellular origins of BE include the stem cells of the mucosal esophageal glands and their ducts, the stem cells of the stomach, residual embryonic cells and circulating bone marrow stem cells. The classical concept of healing a caustic lesion has been replaced by the concept of a cytokine storm, which forms an inflammatory microenvironment eliciting a phenotypic shift toward intestinal metaplasia of the distal esophagus. This review describes the roles of the NOTCH, hedgehog, NF-κB and IL6/STAT3 molecular pathways in the pathogenesis of BE and EAC.

P63 Deficiency and CDX2 Overexpression Lead to Barrett's-Like Metaplasia in Mouse Esophageal Epithelium

BACKGROUND

The cellular origin and molecular mechanisms of Barrett's esophagus (BE) are still controversial. Trans-differentiation is a mechanism characterized by activation of the intestinal differentiation program and inactivation of the squamous differentiation program.

AIMS

Renal capsule grafting (RCG) was used to elucidate whether CDX2 overexpression on the basis of P63 deficiency in the esophageal epithelium may generate intestinal metaplasia.

METHODS

P63^-/-;Villin-Cdx2 embryos were generated by crossing P63^+/- mice with Villin-Cdx2 mice. E18.5 esophagus was xenografted in a renal capsule grafting (RCG) model. At 1, 2, or 4 weeks after RCG, the mouse esophagus was immunostained for a proliferation marker (BrdU), squamous transcription factors (SOX2, PAX9), squamous differentiation markers (CK5, CK4, and CK1), intestinal transcription factors (CDX1, HNF1α, HNF4α, GATA4, and GATA6), intestinal columnar epithelial cell markers (A33, CK8), goblet cell marker (MUC2, TFF3), Paneth cell markers (LYZ and SOX9), enteroendocrine cell marker (CHA), and Tuft cell marker (DCAMKL1).

RESULTS

The P63^-/-;Villin-Cdx2 RCG esophagus was lined with proliferating PAS/AB+ cuboidal cells and formed an intestinal crypt-like structure. The goblet cell markers (TFF3 and MUC2) and intestinal transcription factors (CDX1, HNF1α, HNF4α, GATA4, and GATA6) were expressed although no typical morphology of goblet cells was observed. Other intestinal cell markers including enteroendocrine cell marker (CHA), Paneth cell markers (LYZ and Sox9), and intestinal secretory cell marker (UEA/WGA) were also expressed in the P63^-/-;Villin-Cdx2 RCG esophagus. Squamous cell markers (PAX9 and SOX2) were also expressed, suggesting a transitional phenotype.

CONCLUSION

CDX2 overexpression on the basis of P63 deficiency in esophageal epithelial cells induces Barrett's-like metaplasia in vivo. Additional factors may be needed to drive this transitional phenotype into full-blown BE.

Understanding the cellular origin and progression of esophageal cancer using esophageal organoids

Three-dimensional (3D) organoids are a novel tool to model epithelial cell biology and human diseases of the esophagus. 3D organoid culture systems have been utilized to investigate the pathobiology of esophageal cancer, including both squamous cell carcinoma and adenocarcinoma. Additional organoid-based approaches for study of esophageal development and benign esophageal diseases have provided key insights into esophageal keratinocyte differentiation and mucosal regeneration. These investigations have implications for the identification of esophageal cancer stem cells, as well as the potential to halt malignant progression through induction of differentiation pathways. Patient-derived organoids (PDOs) from human tissue samples allow for unique and faithful in vitro modeling of esophageal cancers, and provide an exciting platform for investigation into personalized medicine and targeted treatment approaches, as well as new models for understanding therapy resistance and recurrent disease. Future directions include high-throughput genomic screening using PDOs, and study of tumor-microenvironmental interactions through co-culture with immune and stromal cells and novel extracellular matrix complexes.

The cellular origins of cancer with particular reference to the gastrointestinal tract

Stem cells or their closely related committed progenitor cells are the likely founder cells of most neoplasms. In the continually renewing and hierarchically organized epithelia of the oesophagus, stomach and intestine, homeostatic stem cells are located at the beginning of the cell flux, in the basal layer of the oesophagus, the isthmic region of gastric oxyntic glands and at the bottom of gastric pyloric-antral glands and colonic crypts. The introduction of mutant oncogenes such as KrasG12D or loss of Tp53 or Apc to specific cell types expressing the likes of Lgr5 and Mist1 can be readily accomplished in genetically engineered mouse models to initiate tumorigenesis. Other origins of cancer are discussed including 'reserve' stem cells that may be activated by damage or through disruption of morphogen gradients along the crypt axis. In the liver and pancreas, with little cell turnover and no obvious stem cell markers, the importance of regenerative hyperplasia associated with chronic inflammation to tumour initiation is vividly apparent, though inflammatory conditions in the renewing populations are also permissive for tumour induction. In the liver, hepatocytes, biliary epithelial cells and hepatic progenitor cells are embryologically related, and all can give rise to hepatocellular carcinoma and cholangiocarcinoma. In the exocrine pancreas, both acinar and ductal cells can give rise to pancreatic ductal adenocarcinoma (PDAC), although the preceding preneoplastic states are quite different: acinar-ductal metaplasia gives rise to pancreatic intraepithelial neoplasia culminating in PDAC, while ducts give rise to PDAC via. mucinous cell metaplasia that may have a polyclonal origin.

Recent insights into the biology of Barrett's esophagus

Barrett's esophagus (BE) is the only known precursor to esophageal adenocarcinoma (EAC), an aggressive cancer with a poor prognosis. Our understanding of the pathogenesis and Barrett's metaplasia is incomplete, and this has limited the development of new therapeutic targets and agents, risk stratification ability, and management strategies. This review outlines current insights into the biology of BE and addresses controversies surrounding cell of origin, cellular reprogramming theories, updates on esophageal epithelial barrier function, and the significance of goblet cell metaplasia and its association with malignant change. Further research into the basic biology of BE is vital as it will underpin novel therapies and improve our ability to predict malignant progression and help identify the minority of patients who will develop EAC.

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.

Transforming human papillomavirus infection and the esophageal transformation zone: prime time for total excision/ablative therapy?

High-risk human papillomavirus (hr-HPV) infection is causal for almost all cervical malignancy (both squamous and adenocarcinoma), 90% of anal neoplasia, 70% of penile tumors, and 25% of head and neck cancers. The shared immunogenetics of cervical and esophageal malignancy suggests that HPV infection could well be a common denominator in the etiology of both cancers. In this regard, we have demonstrated that transcriptionally active hr-HPV (genotypes 16 and 18) is strongly associated with Barrett's dysplasia and esophageal adenocarcinoma. Increasing hr-HPV viral load and integration status has been linked with greater disease severity along the Barrett metaplasia-dysplasia-adenocarcinoma sequence as has been demonstrated in cervical intraepithelial neoplasia and cancer. HPV infections in both the cervix and esophagus are both focal, i.e., present in greater quantities at the squamocolumnar junction (SCJ). HPV affinity is to junctional tissue, as basal cells are particularly accessible at the squamocolumnar transformation zone and especially susceptible to this viral infection. We have postulated that progressive acid damage to the esophagus increases the likelihood of mucosal breaks enabling the virus to enter the basal layer of the transformation zone. The SCJ is the transformation zone of the esophagus and is strikingly similar to the transition zone (ectoendocervical SCJ) of the uterine cervix where almost all high-grade cervical lesions and cancers arise including 80% of adenocarcinomas. These transition zone cells exhibit features of squamous epithelium as well as glandular cells, which have been described in both Barrett's esophagus and cervical mucosa. Barrett's esophagus (BE) is derived from a discrete population of embryonic cells residing at the SCJ. There is loss of SCJ immune-phenotype following excision without regeneration at other junctional sites. Prevention of cervical cancer in up to 80-95% of patients with screen-detected CIN is dependent on the excision/ablation of the entire transformation zone. The persistence of hr-HPV 16/18 following eradication of CIN is a significant risk factor for recurrence. Similarly, we have demonstrated that persistent hr-HPV infection 16/18 and p53 overexpression are associated with treatment failure after endoscopic ablation of BD/EAC. Thus, we believe that excision/ablation of the SCJ in patients with BD/intramucosal EAC should be performed to reduce the potential malignant risk. We propose to test this hypothesis by a multicenter randomized controlled trial whereby patients (both HPV positive and those which are virus negative) will be allocated into two arms: complete excision of the SCJ via endoscopic mucosal resection (EMR) in addition to radiofrequency ablation (RFA) ± EMR of BD/intramucosal EAC (experimental arm) versus current standard of care (RFA ± EMR) of said lesions. Treatment efficacy in both groups will be evaluated by comparing disease elimination, regression/progression, and recurrence (if any). All patients would be entered into an intensive endoscopic surveillance protocol (biannually) for at least 2 years with lesional/neosquamous biopsies to compare the recurrence rate of both dysplasia/neoplasia in both arms. Viral (HPV DNA/p16INK4A/E6/E7 mRNA) and host biomarkers (e.g., p53) will be analyzed both at baseline and posttreatment intervals. A positive study would initiate development of tools best suited for SCJ destruction.

Cellular Origins of Barrett's Esophagus: the Search Continues

PURPOSE OF REVIEW

The cellular origins of Barrett's esophagus remain elusive. In this review, we discuss the potential cellular mechanisms behind squamous to columnar metaplasia as well as the limitations of these proposed mechanisms.

RECENT FINDINGS

Several theories have been proposed, including the reprogramming of native squamous cells, repopulation from submucosal glands, contributions from circulating bone marrow-derived cells, and direct extension of gastric cells. Most recent data support an innate progenitor cell unique to the squamocolumnar junction that can expand into metaplastic glands. Active investigation to clarify each of these potential cells of origin is being pursued, but ultimately each could contribute to the pathogenesis of Barrett's esophagus depending on the clinical context. Nonetheless, identifying cells of origin is critical to understand the molecular mechanisms behind Barrett's esophagus and developing strategies to better treat (and possibly prevent) this increasingly significant premalignant disease.

Origins of Metaplasia in Barrett's Esophagus: Is this an Esophageal Stem or Progenitor Cell Disease?

The incidence of esophageal adenocarcinoma has been increasing in Western countries over the past several decades. Though Barrett's esophagus, in which the normal esophageal squamous epithelium is replaced with metaplastic intestinalized columnar cells due to chronic damage from gastroesophageal reflux, is accepted as the requisite precursor lesion for esophageal adenocarcinoma, the Barrett's esophagus cell of origin and the molecular mechanism underlying esophageal epithelial metaplasia remain controversial. Much effort has been dedicated towards identifying the Barrett's esophagus cell of origin since this could lead to more effective prevention and treatment strategies for both Barrett's esophagus and esophageal adenocarcinoma. Previously, it was hypothesized that terminally differentiated esophageal squamous cells might undergo direct conversion into specialized intestinal columnar cells via the process of transdifferentiation. However, there is increasing evidence that stem and/or progenitor cells are molecularly reprogrammed through the process of transcommitment to differentiate into the columnar cell lineages that characterize Barrett's esophagus. Given that Barrett's esophagus originates at the gastroesophageal junction, the boundary between the distal esophagus and gastric cardia, potential sources of these stem and/or progenitor cells include columnar cells from the squamocolumnar junction or neighboring gastric cardia, native esophageal squamous cells, native esophageal cuboidal or columnar cells from submucosal glands or ducts, or circulating bone marrow-derived cells. In this review, we focus on native esophageal specific stem and/or progenitor cells and detail molecular mediators of transcommitment based on recent insights gained from novel mouse models and clinical observations from patients.

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.

Reflux esophagitis and its role in the pathogenesis of Barrett's metaplasia

Reflux esophagitis damages the squamous epithelium that normally lines the esophagus, and promotes replacement of the damaged squamous lining by the intestinal metaplasia of Barrett's esophagus, the precursor of esophageal adenocarcinoma. Therefore, to prevent the development of Barrett's metaplasia and esophageal adenocarcinoma, the pathogenesis of reflux esophagitis must be understood. We have reported that reflux esophagitis, both in a rat model and in humans, develops as a cytokine-mediated inflammatory injury (i.e., cytokine sizzle), not as a caustic chemical injury (i.e., acid burn), as traditionally has been assumed. Moreover, reflux induces activation of hypoxia inducible factor (HIF)-2α, which enhances the transcriptional activity of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) causing increases in pro-inflammatory cytokines and in migration of T lymphocytes, an underlying molecular mechanism for this cytokine-mediated injury. In some individuals, reflux esophagitis heals with Barrett's metaplasia. A number of possibilities exist for the origin of the progenitor cells that give rise to this intestinal metaplasia including those of the esophagus, the proximal stomach, or the bone marrow. However, intestinal cells are not normally found in the esophagus, the stomach, or the bone marrow. Thus, the development of Barrett's intestinal metaplasia must involve some molecular reprogramming of key developmental transcription factors within the progenitor cell, a process termed transcommitment, which may be initiated by the noxious components of the gastric refluxate. This review will highlight recent studies on the pathogenesis of reflux esophagitis and on reflux-related molecular reprogramming of esophageal squamous epithelial cells in the pathogenesis of Barrett's metaplasia.

The Esophageal Squamous Epithelial Cell-Still a Reasonable Candidate for the Barrett's Esophagus Cell of Origin?

Barrett's esophagus is the metaplastic change of the squamous epithelium lining the distal esophagus into an intestinalized columnar epithelium that predisposes to esophageal adenocarcinoma development. The cell that gives rise to Barrett's esophagus has not been identified definitively, although several sources for the Barrett's esophagus cell of origin have been postulated. One possible source is a fully differentiated squamous epithelial cell or a squamous epithelial progenitor or stem cell native to the esophagus that, through molecular reprogramming, either transdifferentiation or transcommitment, could give rise to an intestinalized columnar cell. Multilayered epithelium found in human patients and rodents with Barrett's esophagus and direct phenotypic conversion of mouse embryonic esophageal epithelium provide support for this. Limitations in current experimental approaches may explain why it has been difficult to fully change an esophageal squamous epithelial cell into an intestinalized columnar cell in vitro.

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.

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.

Barrett's esophagus: recent insights into pathogenesis and cellular ontogeny

Esophageal adenocarcinoma (EAC) has increased 6-fold in its incidence in the last 2 decades. Evidence supports the hypothesis of stepwise progression from normal squamous epithelium → reflux esophagitis → metaplasia (Barrett's esophagus, BE) → dysplasia → adenocarcinoma. The precursor, BE, stands as the bridge connecting the widespread but naive reflux disease and the rare but fatal EAC. The step of metaplasia from squamous to intestine-like columnar phenotype is perhaps pivotal in promoting dysplastic vulnerability. It is widely accepted that chronic inflammation because of gastroesophageal reflux disease leads to the development of metaplasia, however the precise molecular mechanism is yet to be discovered. Additionally, how this seemingly adaptive change in the cellular phenotype promotes dysplasia remains a mystery. This conceptual void is deterring further translational research and clouding clinical decision making. This article critically reviews theories on the pathogenesis of Barrett's esophagus and the various controversies surrounding its diagnosis. We further discuss unanswered questions and future directions, which are vital in formulating effective preventive and therapeutic guidelines for Barrett's esophagus.

Personal and family history of cancer and the risk of Barrett's esophagus in men

The association between Barrett's esophagus (BE) and a personal or family history of cancer other than gastroesophageal remains unknown. To evaluate the effect of personal and family history of certain cancers and cancer treatments on the risk of BE, we analyzed data from a Veterans Affairs case-control study that included 264 men with definitive BE (cases) and 1486 men without BE (controls). Patients with history of esophageal or gastric cancer were excluded. Patients underwent elective esophagogastroduodenoscopy or a study esophagogastroduodenoscopy concurrently with screening colonoscopy to determine BE status. Personal and family history of several types of cancer was obtained from self-reported questionnaires, supplemented and verified by electronic medical-record reviews. We estimated the association between personal and family history of cancer or radiation/chemotherapy, and BE. Personal history of oropharyngeal cancer (1.5% vs. 0.4%) or prostate cancer (7.2% vs. 4.4%) was more frequently present in cases than controls. The association between BE and prostate cancer persisted in multivariable analyses (adjusted odds ratio 1.90; 95% confidence interval 1.07-3.38, P = 0.028) while that with oropharyngeal cancer (adjusted odds ratio 3.63; 95% confidence interval 0.92-14.29, P = 0.066) was attenuated after adjusting for retained covariates of age, race, gastroesophageal reflux disease, hiatal hernia, and proton pump inhibitor use. Within the subset of patients with cancer, prior treatment with radiation or chemotherapy was not associated with BE. There were no significant differences between cases and controls in the proportions of subjects with several specific malignancies in first- or second-degree relatives. In conclusion, the risk of BE in men may be elevated with prior personal history of oropharyngeal or prostate cancer. However, prior cancer treatments and family history of cancer were not associated with increased risk of BE. Further studies are needed to elucidate if there is a causative relationship or shared risk factors between prostate cancer and BE.

Mechanisms of Barrett's oesophagus: intestinal differentiation, stem cells, and tissue models

Barrett's oesophagus (BE) is defined as any metaplastic columnar epithelium in the distal oesophagus which replaces normal squamous epithelium and which predisposes to cancer development. It is this second requirement, the predisposition to cancer, which makes this condition both clinically highly relevant and an important area for ongoing research. While BE has been defined pathologically since the 1950's (Allison and Johnstone, Thorax 1955), and identified as a risk factor for esophageal adenocarcinoma since the 1970's (Naef A.P., et al J Thorac Cardiovasc Surg. 1975), our understanding of the molecular events giving rise to this condition remains limited. Herein we will examine what is known about the intestinal features of BE and how well it recapitulates the intestinal epithelium, including stem identity and function. Finally, we will explore laboratory models of this condition presently in use and under development, to identify new insights they may provide into this important clinical condition.

Barrett esophagus: diagnostic challenges

The incidence of esophageal adenocarcinoma and associated mortality has risen dramatically over the past several decades, and, thus, it is increasingly important to understand its pathogenesis and risk factors. Barrett esophagus is the established precursor to esophageal adenocarcinoma that progresses through a metaplasia-dysplasia-carcinoma sequence. Its risk of transforming to carcinoma is not as high as previously reported and there appears to be a biological heterogeneity among patients with this disease. The overall prevalence of Barrett esophagus in the United States ranges from 1% to 25% and is closer to 5% in patients with gastroesophageal reflux disease. Because of the frequency of Barrett esophagus and associated implications, it is important for the practicing pathologist to have a thorough understanding of this disease and its diagnostic pitfalls. In this review, we will discuss issues associated with the diagnosis of Barrett esophagus, including the definition of Barrett esophagus and its distinction from carditis with intestinal metaplasia. We will also discuss challenges in the grading of dysplasia and new variants of dysplasia, including crypt dysplasia and foveolar-type dysplasia. Finally, we will touch upon the evaluation of dysplasia in endoscopic mucosal resection specimens.

Human papillomavirus and the risk of Barrett's esophagus

Human papillomavirus (HPV) is strongly associated with squamous esophageal cancer. The potential role of HPV in Barrett's esophagus (BE) has been examined but remains unclear. The aim of the study was to determine the prevalence of HPV in esophageal and gastric tissues obtained from patients with and without BE. We designed a cross-sectional study was conducted with prospective enrollment of eligible patients scheduled for esophagogastroduodenoscopy (EGD). All participants had biopsies of endoscopic BE, squamous-lined esophagus, and stomach. Immunohistochemistry (IHC) on formalin-fixed and paraffin-embedded tissue was conducted using monoclonal antibodies. Polymerase chain reaction (PCR) for HPV was performed on DNA extracted from esophageal biopsies snapped frozen within 30 minutes after endoscopic capture. The Roche HPV Linear Array Assay with PGMY primers that has high sensitivity for detecting 37 types of HPV was used. A total of 127 subjects were included: 39 with definitive BE had IHC done on samples from non-dysplastic BE, squamous esophagus, gastric cardia, and gastric body; and 88 control patients without BE had IHC done on squamous esophageal samples, gastric cardia, and gastric body. HPV was not detected in any of the samples in either group. For confirmation, HPV DNA PCR was performed on randomly selected samples from 66 patients (both esophagus and BE from 13 patients with BE, and 53 esophagus from patients without BE); no sample had HPV DNA detected via PCR in the presence of adequate quality control. HPV infection does not play a role in the formation of non-dysplastic Barrett's esophagus in men in the United States.

Barrett's esophagus. Practical issues for daily routine diagnosis

Most clinicians and researchers agree that Barrett's esophagus (BE) is a precancerous condition which, however, is not easily defined. Whether goblet cells must be present or not is a matter of debate and definitions vary worldwide. Although the use of the term "columnar metaplasia" tends to circumvent these issues, it can also be subdivided into those with and without goblet cells. There is some evidence that Barrett's esophagus results from a multistep process in which goblet cells are a secondary event. Hence, Barrett's adenocarcinoma has recently been shown to originate from areas lacking goblet cells. The histological diagnosis of neoplasia is often hampered by marked interobserver variation. New endoscopic techniques allow for local resections of neoplasia with curative intent. Pathologists should know which pieces of information gastroenterologists need for management options: surveillance versus therapy such as endoscopic resection with or endoscopic ablation without histological specimen. The most important information for gastroenterologists is whether there is neoplasia or not; if any, they need to know the grade (low grade, high grade, carcinoma) and risk factors (vessel permeation, poor differentiation, resection complete in case of endoscopic resection, depth of infiltration).

Hepatocyte paraffin 1 antigen as a biomarker for early diagnosis of Barrett esophagus

We evaluated hepatocyte paraffin 1 (HepPar1) antigen expression, a sensitive marker of small intestinal differentiation, in combination with morphologic features to demonstrate intestinal differentiation in cases equivocal for Barrett esophagus (BE). Clinicopathologic features and HepPar1 expression were recorded for 54 BE cases, 45 consistent with reflux esophagitis (RE) cases, and 65 "suspicious" for BE (SBE) cases. The SBE category included RE cases with 2 or more morphologic changes associated with BE or metaplastic reaction to injury (eg, multilayered epithelium, squamous islands, goblet cell mimickers, pancreatic metaplasia). HepPar1 was expressed in all 54 BE cases, 4 of 45 RE cases, and 24 of 65 SBE cases. In SBE cases, 2 or more morphologic changes were associated with HepPar1 expression in 37% of cases (24/65), 3 or more features in 59% (13/22), and 4 or more features in 100% (4/4) (P ≤ .004). The combination of certain morphologic changes and HepPar1 expression in clinically suspicious distal esophageal biopsy cases without goblet cells supports the presence of evolving intestinal metaplasia.

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.

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.

The normal anatomy around the oesophagogastric junction: a histopathologic view and its correlation with endoscopy

The incidence of primary oesophageal adenocarcinoma in Caucasian men has recently been increasing rapidly. Therefore, primary oesophageal adenocarcinoma, columnar-lined oesophagus (CLO) or Barrett's oesophagus and the normal condition of the lower segment of the oesophagus are currently receiving worldwide attention in the medical field. Precise definitions of the anatomical features of the oesophagogastric junction (OGJ) are essential before accurate assessment of CLO can be made. This article reviews the normal morphological features in the OGJ zone to give a closer insight into the histopathology and endoscopic appearance of the OGJ and CLO. We review definitions of the OGJ, the pattern of the squamocolumnar junction (SCJ), oesophageal cardiac-type glands beneath the squamous epithelium, the normal squamous epithelium, columnar islands in squamous-lined mucosa, squamous islands in CLO and newly reported metaplastic changes in the OGJ zone. The nature of the OGJ is clarified in detail through comparison between endoscopically evident and histological features.

Morphologic features are useful in distinguishing Barrett esophagus from carditis with intestinal metaplasia

Barrett esophagus (BE) and carditis with intestinal metaplasia (CIM) differ in their risk of malignancy and implications for patient management, but are difficult to distinguish in mucosal biopsies from the gastroesophageal junction region. The present study was performed to evaluate the role of routine morphology in distinguishing BE from CIM in mucosal biopsies and to assess the degree of interobserver variability in recognizing morphologic parameters that are of significance in making this distinction. Several morphologic features, including presence of crypt disarray and atrophy, incomplete and diffuse intestinal metaplasia, multilayered epithelium, squamous epithelium overlying columnar crypts with intestinal metaplasia, hybrid glands, and esophageal glands/ducts, were significantly associated with a diagnosis of BE. The latter 3 features were observed exclusively in BE biopsies. Furthermore, multiple BE-associated morphologic features were often present together in BE but not CIM biopsies. There was substantial agreement (kappa=0.6) among expert gastrointestinal pathologists for distinguishing BE from CIM even in the absence of clinical/endoscopic information. The interobserver agreement in recognition of BE-associated morphologic features ranged from almost perfect for some features like esophageal glands/ducts (kappa=0.83) to slight for multilayered epithelium (kappa=0.17). In conclusion, our findings indicate that several morphologic features are helpful in distinguishing BE from CIM. The combined presence of multiple BE-associated morphologic features can be used in making this distinction with a high degree of accuracy. Larger prospective studies need to be performed to validate these findings and evaluate the reproducibility of this approach in routine clinical practice.

Duodenal-content reflux into the esophagus leads to expression of Cdx2 and Muc2 in areas of squamous epithelium in rats

The molecular events responsible for the transdifferentiation of epithelial cells of the esophagus to a columnar cell type are not well understood. Cdx2 has been detected in Barrett's esophagus, so we sought evidence of Cdx2 expression during the process of transdifferentiation of the esophageal squamous epithelium into a glandular phenotype. Thirty-two rats underwent an esophago-jejunostomy to produce esophagitis of 20, 25, 30, or 35 weeks of duration. The spectrum of esophageal lesions induced by chronic reflux was examined for expression of Cdx2 and Muc2 by immunohistochemistry. Five animals developed glandular metaplasia and adenosquamous carcinoma, two developed only glandular metaplasia, and two had adenosquamous carcinoma alone. Nuclear Cdx2 expression was detected in 57% (four of seven) and 43% (three of seven) of foci of glandular metaplasia and adenosquamous carcinomas, respectively. Cdx2 staining was detectable in some squamous and some mucus secreting cells. Perinuclear and perivacuolar staining of Muc2 was detected focally in 71% (five of seven) and 57% (four of seven) of areas with glandular metaplasia and adenosquamous carcinoma, respectively. We show that duodenal-content reflux into the esophagus switches on the expression of Cdx2 protein in esophageal keratinocytic cells, promoting a mucinous transdifferentiation process with secretion of intestinal mucin Muc2.

Multilayered epithelium may be found in patients with Barrett's epithelium and dysplasia or adenocarcinoma

To determine if multilayered epithelium (MLE) is a useful prognostic indicator for a benign natural history of Barrett's epithelium, we evaluated endoscopic biopsies from patients with Barrett's epithelium without and with dysplasia and/or adenocarcinoma and from non-Barrett's controls for the presence of MLE. MLE was found in 6% of non-Barrett's controls, 30% of Barrett's patients with no dysplasia, and 14% of Barrett's patients with dysplasia and/or adenocarcinoma. MLE was significantly associated with shorter lengths of Barrett's epithelium in both Barrett's groups. Three of 5 photodynamic therapy patients were noted to develop MLE after therapy. MLE may be found in patients with dysplasia and/or adenocarcinoma and after photodynamic therapy; its presence is not useful as a prognostic indicator for a more benign course of Barrett's. This study confirms that MLE is significantly associated with shorter lengths of Barrett's epithelium.

Pathology of the gastroesophageal junction

The gastroesophageal junction (GEJ) is a poorly defined anatomic area that represents the junction etween the distal esophagus and the proximal stomach (cardia). The true anatomic GEJ corresponds to the most proximal aspect of the gastric folds, which represents an endoscopically apparent transition oint in most individuals. Many, if not most, adults, particularly those with either physiologic or logic GERD, have a proximally displaced Z-line indicating that the histologic squamocolumnar nction (SCJ) is located above the anatomic GEJ. The histologic characteristics of short segments of columnar mucosa located above the anatomic GEJ in these individuals are similar to the gastric cardia, ng composed of either pure mucous glands or mixed mucous glands/oxyntic glands. Although controversial, some authors believe that the cardia is normally composed, at birth, of surface mucinous columnar epithelium and underlying oxyntic glands identical to the gastric corpus, whereas others maintain that the true anatomic cardia is normally composed of mucinous columnar epithelium with underlying mucous glands or mixed mucous and oxyntic glands. However, the preponderance of evidence supports the latter theory and that the length of mucosa composed of either mucous, or mixed mucous glands/oxyntic glands, increases with age and is presumed to be related to ongoing GERD. Inflammation of the true gastric cardia (carditis), which is most often due to H. pylori infection, is difficult to distinguish from columnar metaplasia of the distal esophagus secondary to GERD. From a pathologist's perspective, the differential diagnosis of true gastric carditis from esophageal columnar metaplasia of the distal esophagus in GEJ biopsies is difficult, but a variety of clinical, pathologic, and immunohistochemical methods can be used to help separate these two disorders. Nearly one-third of patients who present for upper GI endoscopy without endoscopic evidence of BE reveal foci of intestinal metaplasia in the GEJ. There are some studies to suggest that the risk of dysplasia and cancer is different in patients with intestinal metaplasia in the cardia related to H. pylori infection versus those with metaplastic columnar epithelium in the distal esophagus related to GERD. Chronic inflammation is generally considered the predominant underlying stimulus for the development of columnar metaplasia in the GEJ, regardless of the etiology. Columnar metaplasia and intestinal metaplasia in the distal esophagus represents a squamous to columnar cell transition and there is some evidence that this occurs through an intermediate, or transitional, phase of intestinalization termed multilayered epithelium. In contrast, intestinal metaplasia that develops in the true gastric cardia secondary to H. pylori infection represents a columnar to columnar metaplastic reaction. This review will focus on the clinical, pathologic, and pathogenetic aspects of GERD and H. pylori-induced inflammation of the GEJ region.

Unraveling the mystery of the gastroesophageal junction: a pathologist's perspective

The gastroesophageal junction (GEJ), which is defined as the point where the distal esophagus joins the proximal stomach (cardia), is a short anatomic area that is commonly exposed to the injurious effects of GERD and/or Helicobacter pylori infection. These disorders often lead to inflammation and intestinal metaplasia (IM) of this anatomic region. The true gastric cardia is an extremely short segment (<0.4 mm) of mucosa that is typically composed of pure mucous glands, or mixed mucous/oxyntic glands that are histologically indistinguishable from metaplastic mucinous columnar epithelium of the distal esophagus. In patients with GERD, whether physiologic or pathologic, the length of cardia-type epithelium increases and extends proximally above the level of the anatomic GEJ into the distal esophagus. Columnar metaplasia of the distal esophagus represents a squamous to columnar metaplastic reaction that develops from an esophageal stem cell and may pass through an intermediate phase characterized by the presence of a type of epithelium that possesses a mixture of squamous and columnar features, termed multilayered epithelium. In contrast, IM of the gastric cardia represents a columnar to columnar cell metaplastic reaction that develops from a gastric stem cell located in the deep foveolar compartment of the gastric mucosa. Intestinal metaplasia, particularly the incomplete type, is widely believed to represent the precursor lesion upon which dysplasia and cancer arises. The frequency of IM is probably greater in metaplastic columnar epithelium in the esophagus secondary to GERD, than in cases of true gastric carditis secondary to H. pylori, and may be a reason why there is a higher risk of carcinoma in the former compared to the latter. A variety of clinical, endoscopic, histologic, and histochemical methods can be used to distinguish GERD-induced columnar metaplasia of the distal esophagus from H. pylori-induced inflammation of true gastric cardia, and these are outlined in this review, but further controlled studies are needed to critically evaluate these techniques. Further prospective trials are needed to adequately evaluate the different etiologic and pathogenetic mechanisms and, most importantly, the risk of malignancy in these two conditions.

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

Barrett esophagus is defined as a specialized intestinal replacing the squamous epithelium of the esophageal mucosa in response to gastroesophageal reflux. Barrett metaplasia is a healing process that develops to protect the esophagus from further damage. Although mechanisms by which Barrett metaplasia evolves toward dysplasia and adenocarcinoma have been extensively studied, the process by which squamous epithelium is replaced by specialized intestinal metaplasia is poorly understood. Barrett esophagus develops when defense mechanisms in the esophageal mucosa (luminal secretion of mucus, bicarbonate, growth factors, etc.) are overwhelmed by an ongoing cycle of mucosal injury and repair. Hydrogen ion, pepsin, trypsin, and bile acids are considered harmful agents that synergistically invade the esophageal mucosa. Areas of destroyed squamous epithelium are then progressively reepithelized by a columnar epithelium that may originate from multipotent stem cells located within the basal layer of the normal esophageal mucosa or in the ducts of submucosal glands.

Epidemiology, pathophysiology, and treatment of Barrett's esophagus: reducing mortality from esophageal adenocarcinoma

The definition of BE has evolved over time. BE is the key premalignant lesion for developing EAC. The epidemiology and pathophysiology of BE is outlined, and risk factors for BE and EAC are reviewed. GERD plays a crucial role in the pathophysiology and the clinical identification of BE. Endoscopy with biopsy is the best tool for diagnosing and surveying patients with BE. Detection of early neoplasia is the present approach to reduce EAC mortality. Novel technology should assist in the early detection of dysplasia to enable targeted therapy. Effective chemopreventive strategies may reduce the risk of progression to EAC.

Ciliated Surface in the Esophagogastric Junction Zone

We have previously reported squamous metaplasia-like change at the esophagogastric junction (EGJ). In the present study, we examined these lesions histologically and by immunohistochemistry and electron microscopy. Samples of EGJ mucosa, 3 cm long and comprising 1.5-cm long portions of both columnar and squamous mucosa, were obtained from 43 esophagectomy resection specimens. Squamous metaplasia-like change was observed in 21 (49%) of the 43 cases. The squamous metaplasia-like change was generally positive with immunohistochemical stains for tubulin and cytokeratins (CKs) 4, 7, 8, 13, and 18, and was generally negative with stains for CKs 10, 14, and 20. This pattern of immunoreactivity is very similar to that of bronchial mucosa. Also, many cilia were detected at the apices of the cells by electron microscopy in 5 (31%) of the 16 cases that were able to be examined. Therefore, squamous metaplasia-like change at the EGJ has both a similar appearance and a similar immunohistochemical profile to respiratory bronchial epithelium. These findings may suggest that squamous metaplasia-like change at the EGJ is not a precursor of Barrett's mucosa but rather is a form of pseudostratified metaplasia.

Barrett's esophagus: histopathologic definitions and diagnostic criteria

Adenocarcinoma of the distal esophagus is rising more rapidly in incidence than any other visceral malignancy in the Western world. It is well established that most, if not all, of these tumors develop in Barrett's esophagus via the metaplasia-dysplasia-carcinoma sequence and could theoretically be detected at an early stage, but despite this, the majority of these tumors are still detected late in their course. This highlights the fact that the goal of effective surveillance for patients at risk for developing an adenocarcinoma of the distal esophagus is still far off. In addition, adenocarcinomas of the esophagogastric junction and gastric cardia are also rising in incidence, but their carcinogenesis and their relation to Barrett's esophagus are still being defined, as are the meaning and significance of the relatively new entities "short-segment Barrett's" and "ultra-short-segment Barrett's". This review attempts to clarify the main histopathologic issues concerned with the definition of Barrett's esophagus, its distinction from intestinal metaplasia of the gastric cardia, as well as the criteria for the histologic diagnosis of dysplasia and carcinoma in Barrett's esophagus.

Immunohistochemical study of neuroendocrine cells at the gastric cardia mucosa

BACKGROUND/AIMS

The gastric cardia mucosa is a narrow band of tissue between the oesophagus and the stomach. The physiological role of this tissue is unknown. This study examined the presence and characteristics of neuroendocrine cells at this site.

METHODS

Biopsy samples were obtained from across normal appearing squamocolumnar junctions. The cardiac mucosa was defined as the presence of special type mucosa composed of mucous secreting glands in the immediate vicinity of oesophageal squamous epithelium. Biopsy specimens were stained with haematoxylin and eosin, alcian blue (pH 2.5) periodic acid Schiff, and modified Giemsa. The chromogranin A and Fontana-Masson stains were used to identify neuroendocrine cells, which were also stained immunohistochemically for gastrin, serotonin, glucagon, pancreatic polypeptide, somatostatin, and vasoactive intestinal peptide.

RESULTS

Chromogranin positive cells were seen in 18 cases with adequate biopsy specimens from the gastric cardia mucosa. These cells were all serotonin positive, but stains for other peptide hormones remained negative. Serotonin positive cells were detected only at the base of foveolae at the periphery of mucous secreting cardiac glands, giving a microscopic appearance resembling that of endocrine cells at the gastric antrum. The presence and numbers of serotonin positive cells did not correlate with chronic inflammation or intestinal metaplasia of the cardiac mucosa. These cells were seen both in Helicobacter pylori positive and negative patients.

CONCLUSIONS

Serotonin positive cells appear to be the sole neuroendocrine cell type at the gastric cardia mucosa. These cells may have a role in regulating the physiology of the gastric cardia mucosa and the lower oesophageal sphincter.

Experimental Barrett's esophagus and the origin of intestinal metaplasia

Many questions remain unanswered regarding the pathogenesis and the cell origin of Barrett's esophagus. Recent studies suggest that progenitor cell populations, which are presumed to reside at the basal layer in the squamous epithelium and at the esophageal glands duct epithelium, may differentiate into a glandular phenotype leading to the development of columnar epithelium in the distal esophagus. Other studies also support the hypothesis that cardiac epithelium may precede the occurrence of specialized intestinal metaplasia. It remains unclear whether cardiac-type epithelium in Barrett's esophagus arises from squamous epithelium or from migration of native cardiac epithelium at the EGJ into the distal esophagus. Experimental animal models of chronic reflux esophagitis, although with some shortcomings when researchers extrapolate the study data to the human situation, have provided interesting insights into possible mechanisms associated with the occurrence of Barrett's esophagus. A better understanding of the molecular mechanisms regulating the development of Barrett's esophagus is necessary for developing new strategies directed toward prevention and treatment of this metaplastic condition with a potential risk for malignant transformation.

Columnar-lined esophagus. Definitions

Recognition of a columnar-lined esophagus requires precise criteria by which to delimit the esophagus and the stomach. Endoscopically recognizable landmarks such as the squamocolumnar junction (SCJ or Z-line) can be used to identify structures at the gastroesophageal junction. Once the SCJ is located proximal to the gastroesophageal junction, a columnar-lined segment of esophagus is visible. If biopsy specimens from the columnar-lined segment show specialized intestinal metaplasia, then the patient has Barrett's esophagus (BE), and the extent of the columnar lining determines if it is short- or long-segment BE.

Prospective evaluation of multilayered epithelium in Barrett's esophagus

OBJECTIVE

We recently identified a distinctive type of multilayered epithelium in two patients with Barrett's esophagus, which shows morphological characteristics of both squamous and columnar epithelium. This study was performed to prospectively evaluate the prevalence of multilayered epithelium in patients with Barrett's esophagus.

METHODS

Mucosal biopsies were obtained from the squamocolumnar junction (Z-line) of 58 patients with endoscopic evidence of esophageal columnar epithelium and from the gastroesophageal junction in 21 patients without endoscopic evidence of esophageal columnar epithelium. Specimens were evaluated for the presence of multilayered epithelium and goblet cells.

RESULTS

Twenty-four of 58 (41%) of the patients with endoscopic evidence of esophageal columnar epithelium had multilayered epithelium compared with only one of 21 patients (5%) in the control group (p = 0.005). Of the 58 patients in the study group, 43 had goblet cell metaplasia and 15 did not (p < 0.001). Only patients with goblet cell metaplasia had multilayered epithelium. Shorter lengths of columnar epithelium were noted in the 24 patients with goblet cells and multilayered epithelium compared with the 19 patients with goblet cells and no multilayered epithelium (p < 0.05).

CONCLUSIONS

Multilayered epithelium is strongly associated with goblet cell metaplasia in patients with endoscopic evidence of esophageal columnar epithelium. These data support the hypothesis that multilayered epithelium may represent a transitional stage in the development of Barrett's esophagus.

Expression of p53-related protein p63 in the gastrointestinal tract and in esophageal metaplastic and neoplastic disorders

p63 is a p53-related DNA-binding protein that helps regulate differentiation and proliferation in epithelial progenitor cells. Its expression has never been evaluated in the human gastrointestinal tract. The aim of this study was to evaluate the expression of p63 in the esophagus and related metaplastic and neoplastic disorders to gain insight into the pathogenesis of these processes. Of particular interest was the expression of p63 in Barrett esophagus (BE) and in BE-associated multilayered epithelium. Multilayered epithelium has been postulated to represent an early precursor to the development of BE primarily because it shares morphologic and immunophenotypic features of both squamous and columnar epithelium, and has been shown prospectively to be highly associated with BE. Routinely processed mucosal biopsy or resection specimens that contained normal esophageal squamous epithelium (n = 20), squamous dysplasia (n = 4), squamous cell carcinoma (n = 7), BE (n = 10), BE-associated multilayered epithelium (n = 13), esophageal mucosal gland ducts (n = 10), BE-associated dysplasia (n = 12), and BE-associated adenocarcinoma (n = 7) were immunostained for p63 to determine the extent and location of staining. p63 staining was compared with the staining patterns observed for p53, Ki 67 (proliferation marker), and cytokeratins (CKs) 13 (squamous marker), 14 (basal squamous marker), 8/18 (columnar marker), and 19 (basal/columnar marker). Expression of p63 messenger RNA (mRNA) isoforms was also analyzed by reverse-transcription polymerase chain reaction of freshly isolated tissues. In the normal esophagus, p63 was expressed in the basal and suprabasal layers of the squamous epithelium and in basal cells that line the mucosal gland ducts but was negative in all other epithelia of the gastrointestinal tract, including the stomach, small intestine, and colon. Similarly, p63 was not expressed in BE, but it, was present in the basal layer of multilayered epithelium in 9 of 13 cases (69%). p63-positive cells in multilayered epithelium and in the mucosal gland duct epithelium were positive for CK8/18 (100%) and CK13 (67% and 30%, respectively) and negative for CK14 (0%), in contrast to p63-positive cells in squamous epithelium, which were positive for CK14 and CK13 (100%) but negative for CK8/18. In neoplastic tissues, p63 was diffusely expressed in all cases of esophageal squamous cell dysplasia and carcinoma but was negative in all cases of esophageal and colorectal adenocarcinoma. The DeltaN isoform of p63 mRNA predominated in all benign and neoplastic squamous tissues examined. p63 may represent a marker of 2 distinct epithelial progenitor cells (basal squamous epithelium and gland duct epithelium) in the esophagus. P63 is upregulated in squamous neoplastic conditions and in this manner may play a role in squamous carcinogenesis. These data also indicate that multilayered epithelium is phenotypically similar to, and may share a lineage relationship with, mucosal gland duct epithelium.

Phenotypic characteristics of a distinctive multilayered epithelium suggests that it is a precursor in the development of Barrett's esophagus

A distinctive type of multilayered epithelium (ME) has been described at the neo-squamocolumnar junction and within columnar mucosa in patients with Barrett's esophagus (BE). This epithelium has morphologic and ultrastructural features of both squamous and columnar epithelium. Multilayered epithelium may represent an early or intermediate stage of columnar metaplasia; therefore, we performed this study to determine the morphologic and biologic characteristics of this epithelium and to gain insight into its derivation. Esophageal mucosal biopsies containing ME from 17 patients with BE were evaluated morphologically, stained with a variety of mucin histochemical stains; and also immunostained with antibodies against cytokeratins (CK) 13 (squamous epithelium marker); 14 (basal squamous epithelium marker) 7, 8/18, 19, and 20 (columnar epithelium markers), MIB-1 (proliferation marker); villin (intestinal brush border protein); and TGFalpha, EGFR, pS2, and hSP (enteric proliferation/differentiation regulatory peptides). The results were compared with normal esophageal squamous epithelium, normal gastric cardia epithelium, specialized-type intestinal epithelium (BE), and esophageal mucosal and submucosal gland duct epithelium. Multilayered epithelium expressed a pattern of mucin production (neutral mucin, sialomucin, and sulfomucin in 88%, 100%, and 71% of cases, respectively) and cytokeratin expression (CK 13 and 19 in the basal "squamoid" cells, CK 7, 8/18, 19, and 20 in the superficial "columnar" cells) similar to that of columnar epithelium in BE, and showed a high capacity for cellular proliferation (Ki-67-positive in 88% of cases) and differentiation (TGFalpha, EGFR, pS2 and villin-positive in 100%, 100%, 93%, and 66% of cases, respectively). The mucosal gland duct epithelium showed a similar phenotypic pattern and, in one case, was seen to give rise to ME at the surface of the mucosa. These data provide evidence in support of the hypothesis that ME represents an early or intermediate stage in the development of esophageal columnar metaplasia (BE). The mucosal gland duct epithelium may contain progenitor cells that can give rise to ME.

Pathogenesis of gastroesophageal reflux and Barrett esophagus

Barrett esophagus is a metaplastic condition that affects the lower esophagus and is a complication of gastroesophageal reflux disease (GERD). Under normal circumstances, the reflux of gastric contents into the esophagus is prevented by a complex barrier at the esophagogastric junction. Dysfunction of the lower esophageal sphincter and the presence of a hiatal hernia lead to failure of this barrier. Esophageal mucosal damage results from the chronic exposure of the esophageal mucosa to gastroduodenal contents and the lack of an effective mucosal defense. This article is an overview of the dysfunction of the esophagogastric junction that leads to GERD. The role of the contents of the reflux and that of Helicobacter pylori infection in the pathogenesis of Barrett esophagus are also summarized.

Pathogenesis of gastroesophageal reflux and Barrett esophagus

Barrett esophagus is a metaplastic condition that affects the lower esophagus and is a complication of gastroesophageal reflux disease (GERD). Under normal circumstances, the reflux of gastric contents into the esophagus is prevented by a complex barrier at the esophagogastric junction. Dysfunction of the lower esophageal sphincter and the presence of a hiatal hernia lead to failure of this barrier. Esophageal mucosal damage results from the chronic exposure of the esophageal mucosa to gastroduodenal contents and the lack of an effective mucosal defense. This article is an overview of the dysfunction of the esophagogastric junction that leads to GERD. The role of the contents of the reflux and that of Helicobacter pylori infection in the pathogenesis of Barrett esophagus are also summarized.

Molecular and clinical differences between adenocarcinomas of the esophagus and of the gastric cardia

Adenocarcinoma of the esophagus (ADCE) with Barrett's mucosa and adenocarcinoma of the cardia (ADCC) are often reported as a single pathological entity. In this study we have used strict anatomical-pathological criteria to distinguish between these two lesions and we have investigated their differences in TP53 mutations, MDM2 gene amplification, and cytokeratin expression. DNA was extracted from the tumor areas of formalin-fixed, paraffin-embedded sections in 26 ADCC and 28 ADCE patients. TP53 mutations were detected by temporal temperature gradient electrophoresis and identified by sequencing. MDM2 amplification was assessed by differential polymerase chain reaction. The expression of cytokeratins 4, 7, and 13 was examined by immunohistochemistry. In ADCC, the male to female ratio was 1.8:1, compared to 27:1 in ADCE. Five ADCC patients had a history of other neoplasms, compared to only one ADCE patient. The two types of tumor differed in the prevalence of TP53 mutations (31% in ADCC and 50% in ADCE) and of MDM2 gene amplification (19% in ADCC and 4% in ADCE), and in the pattern of expression of cytokeratin 7 (positive in 100% of ADCE and in 41% of ADCC) and cytokeratin 13 (positive in 81% of ADCE and in 36.5% of ADCC). ADCE and ADCC differ in their clinical characteristics, in the prevalence of TP53 mutations and MDM2 amplifications, and in the patterns of cytokeratin expression. These results support the notion that ADCC and ADCE are distinct pathological entities.

The role of gastric carditis in metaplasia and neoplasia at the gastroesophageal junction

Adenocarcinomas at the gastroesophageal junction appear to arise from foci of intestinal metaplasia that develop either in the distal esophagus or the proximal stomach (the gastric cardia). Metaplasia is usually a consequence of chronic inflammation, and it is logical to assume that intestinal metaplasia at the gastroesophageal junction develops as a result of chronic inflammation in the epithelia that normally line the junction region. Intestinal metaplasia in the esophagus is known to be a sequela of chronic inflammation in squamous epithelium caused by gastroesophageal reflux disease, whereas intestinal metaplasia in the distal stomach is often a consequence of chronic gastritis caused by Helicobacter pylori infection. For the gastric cardia, the contributions of gastroesophageal reflux disease, H. pylori infection, and other factors to inflammation, metaplasia, and neoplasia are not clear. If physicians are to develop meaningful preventive strategies and specific therapies for tumors of the proximal stomach, a clear understanding of pathogenesis is important. Recent studies on pathogenetic factors for inflammation in cardiac epithelium (gastric carditis) have yielded contradictory results, perhaps because of fundamental differences in the techniques used by different investigators for identifying and sampling the gastric cardia. This report explores the roots of the controversy regarding the role of gastric carditis in the development of metaplasia and neoplasia at the gastroesophageal junction and suggests practical guidelines for biopsy protocols to be used in future studies that will be necessary to resolve these disputes.

Barrett's esophagus: the long and the short of it

Specialized intestinal epithelium occurs more frequently at the gastroesophageal junction than previously anticipated. It can occur either within tongues of mucosa (short segment Barrett's) or just beneath a normal z-line (intestinal metaplasia at the gastroesophageal junction). Whether the etiopathogenesis and the natural history of these two conditions are the same is as yet unclear. The role of gastroesophageal reflux disease (GERD), Helicobacter pylori, and inflammation at the gastroesophageal junction in the pathogenesis of short segment Barrett's and intestinal metaplasia at the gastroesophageal junction needs to be carefully documented. Intestinal metaplasia at the gastroesophageal junction, short segment Barrett's, and Barrett's may represent a continuum of the same disease process. Recent evidence suggests, however, that short segment Barrett's shares similar characteristics with Barrett's but may be distinct from intestinal metaplasia at the gastroesophageal junction. It is conceivable that short segment Barrett's may remain steady or even regress if and when the noxious influence wanes but, with continuing stimulation, short segment Barrett's may lengthen further to become what we observe to be Barrett's. If correct, endogenous or exogenous factors that induce progression need to be identified. Acid and bile reflux and H. pylori are possible candidates acting either singly or synergistically. Finally, the true neoplastic potential of short segment Barrett's needs clarification.

Treatment of Barrett's esophagus by endoscopic laser ablation and antireflux surgery

OBJECTIVE

The regeneration of intestinal metaplasia by squamous epithelium in 17 patients with Barrett's esophagus after endoscopic laser ablation in a reflux-free environment after successful antireflux surgery was prospectively examined.

METHODS

All patients had antireflux surgery, and healing of reflux was verified at postoperative endoscopy and 24-hour esophageal pH monitoring. Thereafter, in 11 patients, the whole Barrett's epithelium was ablated using endoscopic Nd-YAG laser energy in 1 to 8 sessions (mean, 4). The needed energy was 965 to 11,173 joules (mean 4709), or about 1000 joules per centimeter of Barrett's esophagus. Six patients had no laser ablation but were treated by antireflux surgery and served as a control group.

RESULTS

In all laser-treated patients, the regenerated epithelium was histologically of squamous type in the tubular esophagus, but two patients still had intestinal metaplasia in the gastric cardia. In controls, the length of Barrett's esophagus and intestinal metaplasia remained unchanged. The length of follow-up was 26 months after the last laser session and 21 months in the control group.

CONCLUSIONS

The regenerated esophageal epithelium arising after laser ablation in reflux-free environment surgery is of squamous type. This treatment may have a role in preventing the development of esophageal adenocarcinoma arising in Barrett's esophagus.