Cdx genes, inflammation, and the pathogenesis of intestinal metaplasia

Revealing the pathogenesis of gastric intestinal metaplasia based on the mucosoid air-liquid interface

BACKGROUND

Gastric intestinal metaplasia (GIM) is an essential precancerous lesion. Although the reversal of GIM is challenging, it potentially brings a state-to-art strategy for gastric cancer therapeutics (GC). The lack of the appropriate in vitro model limits studies of GIM pathogenesis, which is the issue this work aims to address for further studies.

METHOD

The air-liquid interface (ALI) model was adopted for the long-term culture of GIM cells in the present work. This study conducted Immunofluorescence (IF), quantitative real-time polymerase chain reaction (qRT-PCR), transcriptomic sequencing, and mucoproteomic sequencing (MS) techniques to identify the pathways for differential expressed genes (DEGs) enrichment among different groups, furthermore, to verify novel biomarkers of GIM cells.

RESULT

Our study suggests that GIM-ALI model is analog to the innate GIM cells, which thus can be used for mucus collection and drug screening. We found genes MUC17, CDA, TRIM15, TBX3, FLVCR2, ONECUT2, ACY3, NMUR2, and MAL2 were highly expressed in GIM cells, while GLDN, SLC5A5, MAL, and MALAT1 showed down-regulated, which can be used as potential biomarkers for GIM cells. In parallel, these genes that highly expressed in GIM samples were mainly involved in cancer-related pathways, such as the MAPK signal pathway and oxidative phosphorylation signal pathway.

CONCLUSION

The ALI model is validated for the first time for the in vitro study of GIM. GIM-ALI model is a novel in vitro model that can mimic the tissue micro-environment in GIM patients and further provide an avenue for studying the characteristics of GIM mucus. Our study identified new markers of GIM as well as pathways associated with GIM, which provides outstanding insight for exploring GIM pathogenesis and potentially other related conditions.

Diagnostic Challenges during Inflammation and Cancer: Current Biomarkers and Future Perspectives in Navigating through the Minefield of Reactive versus Dysplastic and Cancerous Lesions in the Digestive System

In the setting of pronounced inflammation, changes in the epithelium may overlap with neoplasia, often rendering it impossible to establish a diagnosis with certainty in daily clinical practice. Here, we discuss the underlying molecular mechanisms driving tissue response during persistent inflammatory signaling along with the potential association with cancer in the gastrointestinal tract, pancreas, extrahepatic bile ducts, and liver. We highlight the histopathological challenges encountered in the diagnosis of chronic inflammation in routine practice and pinpoint tissue-based biomarkers that could complement morphology to differentiate reactive from dysplastic or cancerous lesions. We refer to the advantages and limitations of existing biomarkers employing immunohistochemistry and point to promising new markers, including the generation of novel antibodies targeting mutant proteins, miRNAs, and array assays. Advancements in experimental models, including mouse and 3D models, have improved our understanding of tissue response. The integration of digital pathology along with artificial intelligence may also complement routine visual inspections. Navigating through tissue responses in various chronic inflammatory contexts will help us develop novel and reliable biomarkers that will improve diagnostic decisions and ultimately patient treatment.

Modified Chaishao Liujunzi Decoction inhibits bile acid-induced gastric intestinal metaplasia: from network prediction to experimental verification

Modified Chaishao Liujunzi Decoction (MCLD) is a traditional Chinese medicine formula that is used mainly to improve clinical symptoms, alleviate gastric mucosal inflammation, and improve gastric mucosal lesions in patients with gastric intestinal metaplasia (GIM). GIM is considered a precancerous gastric cancer (GC) lesion (PLGC) and exploring effective intervention measures for GIM is of great importance for the prevention of GC. The purpose of this study was to reveal the potential molecular mechanism of MCLD in improving GIM induced by bile acid (BA) using network pharmacology and experimental validation. Through network pharmacology, we speculated that MCLD could act on GIM by driving the epidermal growth factor receptor (EGFR)/PI3K/AKT/mammalian target of rapamycin (mTOR) pathway. After that, we used deoxycholic acid (DCA) to treat GES-1 cells to simulate BA-induced GIM and observed the effects of MCLD treatment. The results indicate that MCLD can significantly inhibit DCA-induced cell proliferation and down-regulate the expression of pro-inflammatory cytokines and intestinal-specific markers. At the same time, MCLD also negatively regulated the expression of genes and proteins of the EGFR/PI3K/AKT/mTOR pathway. Combination with EGFR agonists and inhibitors suggested that MCLD may improve GIM by inhibiting the EGFR/PI3K/AKT/mTOR pathway, which may be related to its inhibition of DCA-induced cell proliferation through this pathway. In conclusion, MCLD may improve BA-induced GIM through the EGFR/PI3K/AKT/mTOR pathway, as predicted by network pharmacology, and is a potential Chinese medicine prescription for the treatment or reversal of GIM.

Revisiting Proton Pump Inhibitors as Chemoprophylaxis Against the Progression of Barrett's Esophagus

PURPOSE OF REVIEW

Barrett's esophagus (BE) is associated with chronic gastroesophageal reflux disease and is a known precursor to esophageal adenocarcinoma. While endoscopic surveillance strategies and the role for endoscopic eradication therapy have been well established, there has been much interest in identifying chemopreventive agents to disrupt or halt the metaplasia-dysplasia-carcinoma sequence in patients with BE.

RECENT FINDINGS

No pharmacological agent has held more hope in reducing the risk of neoplastic progression in BE than proton pump inhibitors (PPIs). However, data supporting PPIs for chemoprevention have largely been from observational cohort and case-control studies with mixed results. In this review, we revisit the literature and highlight the role of PPIs in patients with BE as it pertains to chemoprophylaxis against the progression of BE to dysplasia and esophageal adenocarcinoma.

Bile Acid Sequestrant Use and Gastric Cancer: A National Retrospective Cohort Analysis

INTRODUCTION

Bile acids have been implicated in gastric carcinogenesis. We hypothesized that bile acid sequestrant medication (BAM) use is associated with a lower gastric cancer (GC) incidence.

METHODS

We assembled a cohort of veterans receiving longitudinal care within the Veterans Health Administration between 2000 and 2020 who completed testing for Helicobacterpylori . The index date was the date of completed H. pylori testing. The primary exposure was the number of filled BAM prescription(s) in the 5 years before the index date. The primary outcome was incident GC, stratified by anatomic subsite. Follow-up began at the index date and ended at the earliest of GC, death, after 2 years of follow-up, or the study end (May 31, 2020). We used Kaplan-Meier curves to visualize differences in GC incidence by exposure group and multivariable Cox proportional hazards models to estimate the association between BAM exposure and anatomic site-specific GC.

RESULTS

Among 417,239 individuals (89% male, mean age 54 years, 63% non-Hispanic White), 4,916 (1.2%) filled at least one BAM prescription, 2,623 of whom filled ≥4. Compared with unexposed individuals, those with ≥4 BAM fills before entry had a lower incidence (adjusted hazard ratio 0.71; 95% confidence interval, 0.37-1.36) of GC, but confidence intervals were wide. Results were consistent irrespective of GC anatomic site.

DISCUSSION

BAMs may have a protective effect against both cardia and noncardia GC. Further research and external validation are needed to confirm these findings.

Coding and non-coding co-expression network analysis identifies key modules and driver genes associated with precursor lesions of gastric cancer

BACKGROUND

Helicobacter pylori infection is the most important risk factor for gastric cancer (GC). Human gastric adenocarcinoma develops after long-term H. pylori infection via the Correa cascade. This carcinogenic pathway describes the progression from gastritis to atrophy, intestinal metaplasia (IM), dysplasia and GC. Patients with atrophy and intestinal metaplasia are considered to have precancerous lesions of GC (PLGC). H. pylori eradication and endoscopy surveillance are currently the only interventions for preventing GC. Better knowledge of the biology of human PLGC may help find stratification markers and contribute to better understanding of biological mechanisms. One way to achieve this is by using co-expression network analysis. Weighted gene co-expression network analysis (WGCNA) is often used to identify modules from co-expression networks and relate them to clinical traits. It also allows identification of driver genes that may be critical for PLGC.

AIM

The purpose of this study was to identify co-expression modules and differential gene expression in dyspeptic patients at different stages of the Correa pathway.

METHODS

We studied 96 gastric biopsies from 78 patients that were clinically classified as: non-active (n = 10) and chronic-active gastritis (n = 20), atrophy (n = 12), and IM (n = 36). Gene expression of coding RNAs was determined by microarrays and non-coding RNAs by RNA-seq. The WGCNA package was used for network construction, module detection, module preservation and hub and driver gene selection.

RESULTS

WGCNA identified 20 modules for coding RNAs and 4 for each miRNA and small RNA class. Modules were associated with antrum and corpus gastric locations, chronic gastritis and IM. Notably, coding RNA modules correlated with the Correa cascade. One was associated with the presence of H. pylori. In three modules, the module eigengene (ME) gradually increased in the stages toward IM, while in three others the inverse relationship was found. One miRNA module was negatively correlated to IM and was used for a mRNA-miRNA integration analysis. WGCNA also uncovered driver genes. Driver genes show both high connectivity within a module and are significantly associated with clinical traits. Some of those genes have been previously involved in H. pylori carcinogenesis, but others are new. Lastly, using similar external transcriptomic data, we confirmed that the discovered mRNA modules were highly preserved.

CONCLUSION

Our analysis captured co-expression modules that provide valuable information to understand the pathogenesis of the progression of PLGC.

Expression of Oocyte Vitellogenesis Receptor Was Regulated by C/EBPα in Developing Follicle of Wanxi White Goose

Yolk precursor was synthesized under regulation of hormone secretion, while the mechanism of its incorporation into follicle is still unknown. The reproductive hormones, oocyte vitellogenesis receptor (OVR) expression at pre-, early-, peak- and ceased-laying period, and localization of Wanxi White goose were determined in this study. The results showed that the concentration of LH was lowest in serum at peak laying period compared to the other periods (p < 0.01). Moreover, the concentration of E2 was highest (p < 0.01) in serum at early laying period than that of other periods. Moreover, the gene expression level of OVR was highest at ceased laying period compared to other periods (p = 0.014) and was higher in developing follicles than other follicles (p < 0.01). The OVR was distributed in the granular cell layer and decreased with the maturation of follicles. Five transcription factors were predicted in the promoter of OVR, then were screened and verified by overexpression in granulosa cells. C/EBPα and MF3 significantly stimulated the expression of OVR. The combined overexpression of C/EBPα and OVR significantly stimulated the transportation of lipid from culture medium to cytoplasm. In conclusion, C/EBPα is the key transcription factor promoting OVR expression in goose follicle granulosa cells.

Gastric intestinal metaplasia: when to treat? How to treat?

PURPOSE OF REVIEW

Gastric intestinal metaplasia (GIM) is an attractive target for surveillance and treatment as it can progress to gastric adenocarcinoma (GAC). Yet, GIM remains a challenging area for clinicians as most patients do not progress to cancer, and there are conflicting data regarding the benefits of surveillance and therapy. This review aims to summarize recently published GIM surveillance guidelines, to discuss, which patients with GIM may benefit from treatment, and to review pivotal and recent literature on GIM therapy.

RECENT FINDINGS

Guidelines published by American, British, and European gastroenterology societies do not recommend universal surveillance, but do suggest endoscopic surveillance in patients with risk factors for progression to GAC. Although light examination for at least 7 min and mapping biopsies may increase yield for dysplasia and GAC. In randomized trials, Helicobacter pylori eradication reduced risk of dysplasia and cancer. In GIM with visible dysplasia and early-stage GAC, endoscopic resection improves quality of life without reducing survival compared with surgery. Endoscopic ablation therapies have shown promise for invisible or extensive dysplasia.

SUMMARY

Endoscopic resection is appropriate for visible dysplasia and early-stage GAC without high-risk features that persists despite H. pylori eradication therapy. Prospective studies are needed to assess the utility of endoscopic ablation in GIM.

Esophageal Microenvironment: From Precursor Microenvironment to Premetastatic Niche

Esophageal cancer (EC) is the sixth most deadly cancer, and its incidence is still increasing year by year. Although the researches on the molecular mechanisms of EC have been widely carried out and incremental progress has been made, its overall survival rate is still low. There is cumulative evidence showing that the esophageal microenvironment plays a vital role in the development of EC. In precancerous lesions of the esophagus, high-risk environmental factors can promote the development of precancerous lesions by inducing the production of inflammatory factors and the recruitment of immune cells. In the tumor microenvironment, tumor-promoting cells can inhibit anti-tumor immunity and promote tumor progression through a variety of pathways, such as bone marrow-derived suppressor cells (MDSCs), tumor-associated fibroblasts (CAFs), and regulatory T cells (Tregs). The formation of extracellular hypoxia and acidic microenvironment and the change of extracellular matrix stiffness are also important factors affecting tumor progression and metastasis. Simultaneously, primary tumor-derived cytokines and bone marrow-derived immune cells can also promote the formation of pre-metastasis niche of EC lymph nodes, which are beneficial to EC lymph node metastasis. Further research on the specific mechanism of these processes in the occurrence, development, and metastasis of each EC subtype will support us to grasp the overall pre-cancerous prevention, targeted treatment, and metastatic assessment of EC.

Crosstalk Between DNA Damage and Inflammation in the Multiple Steps of Gastric Carcinogenesis

Over the last years, intensive investigations in molecular biology and cell physiology extended tremendously the knowledge about the association of inflammation and cancer. In frame of this paradigm, the human pathogen Helicobacter pylori triggers gastritis and gastric ulcer disease, and contributes to the development of gastric cancer. Mechanisms, by which the bacteria-induced inflammation in gastric mucosa leads to intestinal metaplasia and carcinoma, are represented in this review. An altered cell-signaling response and increased production of free radicals by epithelial and immune cells account for the accumulation of DNA damage in gastric mucosa, if infection stays untreated. Host genetics and environmental factors, especially diet, can accelerate the process, which offers the opportunity of intervention based on a balanced nutrition. It is supposed that inflammation might influence stem- or progenitor cells in gastric tissue predisposing for metaplasia or tumor relapse. Herein, DNA is strongly mutated and labile, which restricts therapy options. Thus, the understanding of the mechanisms that underlie gastric carcinogenesis will be of preeminent importance for the development of strategies for screening and early detection. As most gastric cancer patients face late-stage disease with a poor overall survival, the development of multi-targeted therapeutic intervention strategies is a major challenge for the future.

The cyclical hit model: how paligenosis might establish the mutational landscape in Barrett's esophagus and esophageal adenocarcinoma

PURPOSE OF REVIEW

In this review, we explore a paligenosis-based model to explain Barrett's esophagus development and progression: 'the cyclical hit model.'

RECENT FINDINGS

Genomic analyses have highlighted the high mutational burden of esophageal adenocarcinoma, Barrett's esophagus, and even normal esophageal epithelium. Somatic mutations in key genes including TP53 occur early in the neoplastic progression sequence of Barrett's esophagus, whereas chromosomal amplification resulting in oncogene activation occurs as a critical late event. Paligenosis is a shared injury response mechanism characterized by activation of autophagy, expression of progenitor markers, and increased mTORC signaling-induced cell-cycle reentry. In the setting of chronic injury/inflammation, cycles of paligenosis may allow accumulation of mutations until eventually the mutational burden, in concert perhaps with mutations in key driver oncogenes, finally alters the cell's ability to redifferentiate, leading to the emergence of a potential neoplastic clone.

SUMMARY

Under conditions of chronic gastroesophageal refluxate exposure, the normal esophageal squamous epithelium might undergo multiple cycles of paligenosis, allowing initially silent mutations to accumulate until key events impart mutant clones with an oncogenic survival advantage.

Intestinal regulation of suppression of tumorigenicity 14 (ST14) and serine peptidase inhibitor, Kunitz type -1 (SPINT1) by transcription factor CDX2

The type II membrane-anchored serine protease, matriptase, encoded by suppression of tumorgenicity-14 (ST14) regulates the integrity of the intestinal epithelial barrier in concert with its inhibitor, HAI-1 encoded by serine peptidase inhibitor, Kunitz type -1 (SPINT1). The balance of the protease/inhibitor gene expression ratio is vital in preventing the oncogenic potential of matriptase. The intestinal cell lineage is regulated by a transcriptional regulatory network where the tumor suppressor, Caudal homeobox 2 (CDX2) is considered to be an intestinal master transcription factor. In this study, we show that CDX2 has a dual function in regulating both ST14 and SPINT1, gene expression in intestinal cells. We find that CDX2 is not required for the basal ST14 and SPINT1 gene expression; however changes in CDX2 expression affects the ST14/SPINT1 mRNA ratio. Exploring CDX2 ChIP-seq data from intestinal cell lines, we identified genomic CDX2-enriched enhancer elements for both ST14 and SPINT1, which regulate their corresponding gene promoter activity. We show that CDX2 displays both repressive and enhancing regulatory abilities in a cell specific manner. Together, these data reveal new insight into transcriptional mechanisms controlling the intestinal matriptase/inhibitor balance.

Are Gastric and Esophageal Metaplasia Relatives? The Case for Barrett's Stemming from SPEM

Chronic injury and inflammation in the esophagus can cause a change in cellular differentiation known as metaplasia. Most commonly, the differentiation changes manifest as Barrett's esophagus (BE), characterized by the normal stratified squamous epithelium converting into a cuboidal-columnar, glandular morphology. BE cells can phenotypically resemble specific normal cell types of the stomach or intestine, or they can have overlapping phenotypes in disorganized admixtures. The stomach can also undergo metaplasia characterized by aberrant gastric or intestinal differentiation patterns. In both organs, it has been argued that metaplasia may represent a recapitulation of the embryonic or juvenile gastrointestinal tract, as cells access a developmental progenitor genetic program that can help repair damaged tissue. Here, we review the normal development of esophagus and stomach, and describe how BE represents an intermixing of cells resembling gastric pseudopyloric (SPEM) and intestinal metaplasia. We discuss a cellular process recently termed "paligenosis" that governs how mature, differentiated cells can revert to a proliferating progenitor state in metaplasia. We discuss the "Cyclical Hit" theory in which paligenosis might be involved in the increased risk of metaplasia for progression to cancer. However, somatic mutations might occur in proliferative phases and then be warehoused upon redifferentiation. Through years of chronic injury and many rounds of paligenosis and dedifferentiation, eventually a cell with a mutation that prevents dedifferentiation may arise and clonally expand fueling stable metaplasia and potentially thereafter acquiring additional mutations and progressing to dysplasia and cancer.

Chemoprevention of Barrett's Esophagus and Esophageal Adenocarcinoma

Barrett's esophagus is common in Western countries, but progression to esophageal adenocarcinoma is uncommon. Chemoprevention therefore needs to consider whether benefits outweigh risks given an otherwise healthy population. This will depend on the particular population at risk and the relative safety of a potential preventive agent. Most evidence regarding the potential benefit of chemoprevention of Barrett's esophagus and prevention of progression to esophageal adenocarcinoma is based on observational studies such as case-control and cohort studies. Given the potential benefits and relatively low risks, patients with BE should receive once-daily PPI therapy, but routine use of twice-daily PPI is not recommended unless necessitated by poor control of reflux symptoms or esophagitis. Recent data suggest that the inverse associations between aspirin/NSAID use and esophageal adenocarcinoma may be the result of reducing neoplastic progression (from metaplasia to dysplasia and carcinoma) rather than initiation of Barrett's esophagus. While substantial associative data suggest a potential benefit of aspirin and nonaspirin NSAIDs in reducing the risk of progression of Barrett's esophagus, the low risk of progression and the potential risks (gastrointestinal bleeding, complicated ulcer disease, hemorrhagic stroke) do not warrant routine use, unless dictated by cardiovascular risk. Chemoprevention after mucosal ablation in those at highest risk of post-ablation recurrence (dysplastic Barrett's) is currently under investigation.

Role of HOX Genes in Stem Cell Differentiation and Cancer

HOX genes encode an evolutionarily conserved set of transcription factors that control how the phenotype of an organism becomes organized during development based on its genetic makeup. For example, in bilaterian-type animals, HOX genes are organized in gene clusters that encode anatomic segment identity, that is, whether the embryo will form with bilateral symmetry with a head (anterior), tail (posterior), back (dorsal), and belly (ventral). Although HOX genes are known to regulate stem cell (SC) differentiation and HOX genes are dysregulated in cancer, the mechanisms by which dysregulation of HOX genes in SCs causes cancer development is not fully understood. Therefore, the purpose of this manuscript was (i) to review the role of HOX genes in SC differentiation, particularly in embryonic, adult tissue-specific, and induced pluripotent SC, and (ii) to investigate how dysregulated HOX genes in SCs are responsible for the development of colorectal cancer (CRC) and acute myeloid leukemia (AML). We analyzed HOX gene expression in CRC and AML using information from The Cancer Genome Atlas study. Finally, we reviewed the literature on HOX genes and related therapeutics that might help us understand ways to develop SC-specific therapies that target aberrant HOX gene expression that contributes to cancer development.

SOX2 Inhibition Promotes Promoter Demethylation of CDX2 to Facilitate Gastric Intestinal Metaplasia

BACKGROUND

Gastric intestinal metaplasia (IM) is regarded as a premalignant lesion, conferring risks for gastric cancer development. An intestinal transcription factor, CDX2, plays a vital role in establishing and maintaining IM. SOX2, an HMG-box transcription factor, is expressed in normal gastric mucosa and downregulated in IM. Therefore, it is important to elucidate the mutual interaction of SOX2 and CDX2 in gastric IM.

AIMS

This study aims to evaluate the negative correlation between SOX2 and CDX2 in mRNA expression and promoter methylation and to illuminate the effect of SOX2 on the promoter methylation of CDX2.

METHODS

Immunohistochemistry, real-time PCR and methylation-specific polymerase chain reaction assays were performed to evaluate the expression and promoter methylation of SOX2 and CDX2 in IM tissues from patients. SOX2 knockdown and CDX2 overexpression were performed in GES-1 cells to further clarify the relationship between SOX2 and CDX2.

RESULTS

A negative correlation between SOX2 and CDX2 was found in 120 gastric IM specimens. Additionally, significant DNA demethylation of CDX2 promoter in clinical IM specimens was observed concomitantly with partial methylation of the SOX2 promoter. Furthermore, SOX2 knockdown in GES-1 cells triggered promoter demethylation of CDX2. Finally, the phenotype shift of gastric intestinal metaplasia in GES-1 cells, marked by MUC2 expression, was effectively induced by the combination of SOX2 RNAi and CDX2 overexpression.

CONCLUSIONS

Aberrant DNA methylation of SOX2 and CDX2 genes contributes to the development of IM. Notably, SOX2 may play a role in establishing and maintaining the methylation status of the CDX2 gene in gastric tissues and cells.

[Pathogenetic aspects in precursor lesions of gastrointestinal tumors]

The pathogenesis of precursor lesions of gastrointestinal tumors is manifested in many ways. In the esophagus an aberrant genetic expression of intestinal transcription factors, such as CDX2 is initiated by local environment factors. During the subsequent dysplasia to carcinoma sequence, chromosomal gain and loss of genes occurs. A 4-color fluorescence in situ hybridization (FISH) assay can be applied in dysplasia as well as in Barrett's adenocarcinoma to define prognostic marker combinations. In the gastric carcinogenesis sequence the gene expression of CDX1 is regulatively dependent on an interplay between inflammation and promotor methylation. In the colon sessile serrated adenomas show a sequence with initial BRAF mutation and late onset of MLH1 promotor hypermethylation with consecutive potential cancer progression. This event is accompanied by an increase of intraepithelial lymphocytes, which is an easy to use tool for routine diagnostics using H&E sections. Next generation sequencing (NGS) investigations of germline mutations in colorectal cancer revealed a spectrum of mutations with low penetration in the field of mismatch repair proteins as well as the APC gene. An individual risk stratification for penetration of these germline mutations is necessary. In conclusion, genetics, phenotypes and terminology of gastrointestinal precursor lesions are unified to a mutually influencing concept within medicine.

Diabetes-induced mechanophysiological changes in the esophagus

Esophageal disorders are common in diabetes mellitus (DM) patients. DM induces mechanostructural remodeling in the esophagus of humans and animal models. The remodeling is related to esophageal sensorimotor abnormalities and to symptoms frequently encountered by DM patients. For example, gastroesophageal reflux disease (GERD) is a common disorder associated with DM. This review addresses diabetic remodeling of esophageal properties and function in light of the Esophagiome, a scientifically based modeling effort to describe the physiological dynamics of the normal, intact esophagus built upon interdisciplinary approaches with applications for esophageal disease. Unraveling the structural, biomechanical, and sensory remodeling of the esophagus in DM must be based on a multidisciplinary approach that can bridge the knowledge from a variety of scientific disciplines. The first focus of this review is DM-induced morphodynamic and biomechanical remodeling in the esophagus. Second, we review the sensorimotor dysfunction in DM and how it relates to esophageal remodeling. Finally, we discuss the clinical consequences of DM-induced esophageal remodeling, especially in relation to GERD. The ultimate aim is to increase the understanding of DM-induced remodeling of esophageal structure and sensorimotor function in order to assist clinicians to better understand the esophageal disorders induced by DM and to develop better treatments for those patients.

Mechanisms of esophageal adenocarcinoma formation and approaches to chemopreventive intervention

The incidence of esophageal adenocarcinoma (EAC), a debilitating and highly lethal malignancy, has risen dramatically over the past 40 years in the United States and other Western countries. To reverse this trend, EAC prevention and early detection efforts by clinicians, academic researchers and endoscope manufacturers have targeted Barrett's esophagus (BE), the widely accepted EAC precursor lesion. Data from surgical, endoscopic and pre-clinical investigations strongly support the malignant potential of BE. For patients with BE, the risk of developing EAC has been estimated at 11- to 125-fold greater than that of the individual at average risk. Nevertheless, screening for BE in symptomatic patients (ie, with symptoms of reflux) and surveillance in patients diagnosed with BE have not had a substantial impact on the incidence, morbidity or mortality of EAC; the overwhelming majority of EAC patients are diagnosed without a pre-operative diagnosis of BE. This article will discuss the current state of the science of esophageal adenocarcinoma prevention, including ideas about carcinogenesis and its underlying genomic and molecular level mechanisms, and suggest strategies for a systems approach to targeted preventive management.

Immature myeloid progenitors promote disease progression in a mouse model of Barrett's-like metaplasia

Cdx2, an intestine specific transcription factor, is expressed in Barrett's esophagus (BE). We sought to determine if esophageal Cdx2 expression would accelerate the onset of metaplasia in the L2-IL-1β transgenic mouse model for Barrett's-like metaplasia. The K14-Cdx2::L2-IL-1β double transgenic mice had half as many metaplastic nodules as control L2-IL-1β mice. This effect was not due to a reduction in esophageal IL-1β mRNA levels nor diminished systemic inflammation. The diminished metaplasia was due to an increase in apoptosis in the K14-Cdx2::L2-IL-1β mice. Fluorescence activated cell sorting of immune cells infiltrating the metaplasia identified a population of CD11b+Gr-1+ cells that are significantly reduced in K14-Cdx2::L2-IL-1β mice. These cells have features of immature granulocytes and have immune-suppressing capacity. We demonstrate that the apoptosis in K14-Cdx2::L2-IL-1β mice is CD8+ T cell dependent, which CD11b+Gr-1+ cells are known to inhibit. Lastly, we show that key regulators of CD11b+Gr-1+ cell development, IL-17 and S100A9, are significantly diminished in the esophagus of K14-Cdx2::L2-IL-1β double transgenic mice. We conclude that metaplasia development in this mouse model for Barrett's-like metaplasia requires suppression of CD8+ cell dependent apoptosis, likely mediated by immune-suppressing CD11b+Gr-1+ immature myeloid cells.

Surgical Models of Gastroesophageal Reflux with Mice

Multiple surgical procedures have been reported to induce gastroesophageal reflux in animals. Herein, we report three surgical models with mice aiming to induce reflux of gastric contents, duodenal contents or mixed contents. Surgical procedures and general principles have been described in detail. A researcher with surgical experience should be able to grasp the technique after a short period of practice. After surgery, most mice can survive and develop reflux esophagitis similar to that in humans. However, it should be noted that histological differences between mouse and human esophagus are the inherent limitations of these surgical models. If used for research on Barrett's esophagus and adenocarcinoma, these procedures may need to be combined with genetic modifications.

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.

Inhibition of Hedgehog signaling in the gastrointestinal tract: targeting the cancer microenvironment

This review summarizes emerging information regarding the Hedgehog (Hh) signaling pathway during neoplastic transformation in the gastrointestinal tract. Although there is a role for the well-established canonical pathway in which Hedgehog ligands interact with their receptor Patched, there is sufficient evidence that downstream components of the Hh pathway, e.g., Gli1, are hijacked by non-Hh signaling pathways to promote the conversion of the epithelium to dysplasia and carcinoma. We review the canonical pathway and involvement of primary cilia, and then focus on current evidence for Hh signaling in luminal bowel cancers as well as accessory organs, i.e., liver, pancreas and biliary ducts. We conclude that targeting the Hh pathway with small molecules, nutriceuticals and other mechanisms will likely require a combination of inhibitors that target Gli transcription factors in addition to canonical modulators such as Smoothened.

Functional promoter variants in sphingosine 1-phosphate receptor 3 associate with susceptibility to sepsis-associated acute respiratory distress syndrome

The genetic mechanisms underlying the susceptibility to acute respiratory distress syndrome (ARDS) are poorly understood. We previously demonstrated that sphingosine 1-phosphate (S1P) and the S1P receptor S1PR3 are intimately involved in lung inflammatory responses and vascular barrier regulation. Furthermore, plasma S1PR3 protein levels were shown to serve as a biomarker of severity in critically ill ARDS patients. This study explores the contribution of single nucleotide polymorphisms (SNPs) of the S1PR3 gene to sepsis-associated ARDS. S1PR3 SNPs were identified by sequencing the entire gene and tagging SNPs selected for case-control association analysis in African- and ED samples from Chicago, with independent replication in a European case-control study of Spanish individuals. Electrophoretic mobility shift assays, luciferase activity assays, and protein immunoassays were utilized to assess the functionality of associated SNPs. A total of 80 variants, including 29 novel SNPs, were identified. Because of limited sample size, conclusive findings could not be drawn in African-descent ARDS subjects; however, significant associations were found for two promoter SNPs (rs7022797 -1899T/G; rs11137480 -1785G/C), across two ED samples supporting the association of alleles -1899G and -1785C with decreased risk for sepsis-associated ARDS. In addition, these alleles significantly reduced transcription factor binding to the S1PR3 promoter; reduced S1PR3 promoter activity, a response particularly striking after TNF-α challenge; and were associated with lower plasma S1PR3 protein levels in ARDS patients. These highly functional studies support S1PR3 as a novel ARDS candidate gene and a potential target for individualized therapy.

How microbiomes influence metazoan development: insights from history and Drosophila modeling of gut-microbe interactions

Since Metchnikoff developed his views on the intestinal microflora, much effort has been devoted to understanding the role of gut microbiomes in metazoan physiology. Despite impressive data sets that have been generated by associating a phenotype-causing commensal community with its corresponding host phenotype, the field continues to suffer from descriptive and often contradictory reports. Hence, we cannot yet draw clear conclusions as to how the modifications of microbiomes cause physiological changes in metazoans. Unbiased, large-scale genetic screens to identify key genes, on both microbial and host sides, will be essential to gain mechanistic insights into gut-microbe interactions. The Drosophila genome-commensal microbiome genetic model has proven to be well suited to dissect the complex reciprocal cross talk between the host and its microbiota. In this review, we present a historical account, current views, and novel perspectives for future research directions based on the insights gleaned from the Drosophila gut-microbe interaction model.

Relationships of CDXs and apical sodium-dependent bile acid transporter in Barrett’s esophagus

Barrett’s esophagus (BE) is characterized by intestinal metaplasia with the differentiated epithelium replaced by another type of epithelium morphologically similar to normal intestinal epithelium. The metaplasia is preceded by bile and acid reflux into the esophagus. BE is a premalignant condition associated with increased risk of esophageal cancer, especially esophageal adenocarcinoma. The Caudal-related homeodomain transcription factors Caudal-related homeodomain transcription factor CDX1 and CDX2 are expressed exclusively in the small and large intestine, playing important roles in proliferation and differentiation of intestinal epithelial cells. Ectopic expression of CDX1 and CDX2 occurs in BE. The apical sodium-dependent bile acid transporter (ASBT) is expressed primarily in terminal ileum where it is a key factor for intestinal reabsorption of bile salts. In addition to upregulation of CDX1 and CDX2, ASBT expression is up-regulated in BE. Furthermore, both CDX1/CDX2 and ASBT expressions are down-regulated in high-grade esophageal dysplasia. The alteration of the above-mentioned factors calls for attention: what is the relationship between CDXs and ASBT aberrant expression in BE? In this commentary, we discuss this issue on basis of the recent study done by Ma et al.

The association of single nucleotide polymorphisms in the calcitonin gene with primary osteoarthritis of the knee in Mexican mestizo population

Primary osteoarthritis (OA) is a multifactorial disorder with several genetics factors involved. Calcitonin (CT) has been suggested to possess chondroprotective effects and could play an important role in the pathogenesis of OA. The aim of this study was to investigate whether genetic variations in or adjacent to the CT gene may be associated with primary OA of the knee in Mexican mestizo population. We conducted a case-control study to investigate the association between six single nucleotide polymorphisms at the CT locus and OA of the knee in 107 cases and 106 controls. Cases were patients >40 years of age, with a body mass index (BMI) ≤ 27 and a radiologic score for OA of the knee ≥ 2. Controls were subjects >40 years of age with a radiologic score <2. Non-conditional logistic regression was developed to evaluate risk magnitude. The G allele and GT genotype frequencies of the G-706T polymorphism and the C allele and CC genotype of the C-778T polymorphism were significantly higher in patients with OA than in control subjects. The GG genotype of the G-706T was associated with lower risk of the development of OA of the knee. According to the results, the G-706T and the C-778T polymorphisms were related to the Cdx1 and Mzf1 transcription factor binding sites, respectively. Therefore, these could be related to regulation sequences in the CT gene promoter. In conclusion, G-706T and C-778T polymorphisms in the CT gene are significantly associated with the development of primary OA of the knee.

Intestinal metaplasia and the risk of gastric cancer in an immigrant asian population

The development of intestinal metaplasia (IM) has been purported to be a critical step in the pathogenesis of gastric cancer. However, the natural history of IM in migrant human populations has not been well elucidated. The purpose of this study was to determine the risk of gastric cancer posed by IM in Asian immigrants undergoing gastric cancer screening. A retrospective review of Asian immigrants found to have IM during screening was conducted over an 18-month period. In total, 222 patients were found to have IM. Altogether, 24% had a history of smoking, 48% had a family history of gastric cancer, and 52% had a history of Helicobacter pylori (H. pylori) infection with a 96% eradication rate. Patients with stable IM (SIM) were then compared with those who developed high risk pathology (HRP), specifically dysplasia and/or adenocarcinoma. Thirty-five patients (16%) were included in the HRP group, 31 with dysplasia (14%) and 4 with adenocarcinoma (2%). Of those with dysplasia, 55% demonstrated regression to IM over the course of follow-up. Patients in the SIM group were more likely to be female (60% vs. 31%, P = 0.002) and more likely to have had a normal biopsy during follow-up (32% vs. 9%, P = 0.005). Odds ratios for IM stability were 3.3 (95% CI 1.5-7.0) and 5.0 (95% CI 1.5-17.1) for female gender and presence of a normal biopsy, respectively. Intestinal metaplasia in immigrant Asian populations is predominantly a stable histologic finding associated with a low rate of persistent dysplasia and adenocarcinoma.

Math1/Atoh1 contributes to intestinalization of esophageal keratinocytes by inducing the expression of Muc2 and Keratin-20

BACKGROUND

Esophageal intestinal metaplasia, also known as Barrett's esophagus, is the replacement of the normal epithelium with one that resembles the intestine morphologically. Generally, this includes intestinal mucin-secreting goblet cells. Barrett's esophagus is an important risk factor for adenocarcinoma development. In-vitro models for Barrett's esophagus have not, to date, focused on the induction of goblet cells in Barrett's epithelium.

AIMS

To explore the contribution of Math1/Atoh1 to induction of Barrett's esophagus and intestinal mucin-secreting goblet cells from normal human esophageal epithelium.

METHODS

We explored the level and pattern of Math1/Atoh1 mRNA and protein expression in human Barrett's esophagus. Then, using retroviral-mediated gene expression, we induced Math1 mRNA and protein expression in a human esophageal keratinocyte cell line. We evaluated the effects of this ectopic Math1 expression on cell proliferation and gene expression patterns in cells cultured under two-dimensional and three-dimensional tissue-engineering conditions.

RESULTS

Math1/Atoh1 mRNA and protein are detected in human Barrett's esophagus specimens, but the mRNA levels vary substantially. In the keratinocyte expression studies, we observed that Math1/Atoh1 ectopic expression significantly reduced cell proliferation and altered cell morphology. Moreover, Math1/Atoh1 expression is associated with a more intestinalized gene expression pattern that is distinct from that reported in after studies using other intestinal transcription factors. Most significantly, we observe the induction of the Barrett's esophagus markers Mucin-2 and Keratin-20 with Math1/Atoh1 expression.

CONCLUSIONS

We conclude that ectopic Math1/Atoh1 expression makes unique contributions to intestinalization of the esophageal epithelium in Barrett's esophagus.

High frequency of Helicobacter pylori in the esophageal mucosa of dyspeptic patients and its possible association with histopathological alterations

BACKGROUND

Helicobacter pylori gastric colonization is known to be high in symptomatic subjects. However, only a few reports on the presence of H. pylori in the esophageal mucosa have been published. The aim of this study was to assess the frequency of H. pylori in the esophagus of dyspeptic patients and its association with histopathology.

METHODS

The presence of H. pylori in the gastroesophageal mucosa was detected by fluorescence in situ hybridization (FISH) and PCR analysis of DNA extracted from gastric and esophageal biopsies of 82 symptomatic patients, using genus- and species-specific PCR primers. Alterations in the gastroesophageal mucosa were assessed by conventional histological techniques.

RESULTS

H. pylori in the stomach was detected by PCR and FISH, respectively, in 61% (n=43) and 90% (n=63) of dyspeptic patients, and in the esophagus in 70% (n=44) and 73% (n=46). The prevalence of cagA-positive strains by PCR varied from 50% (n=35) in the gastric mucosa to 65% (n=41) in the esophageal mucosa. By combining the results of both methods, H. pylori was present in the gastroesophageal mucosa in 86% (n=68) of patients. The association of the presence of bacteria, including H. pylori, in the esophageal mucosa with histopathological alterations was statistically significant between microabscesses and bacteria (r=0.656, p<0.0001) and PCR detection and pseudogoblet cells (r=0.25, p<0.047).

CONCLUSIONS

This is the first report of the occurrence of H. pylori in the esophageal mucosa from dyspeptic Venezuelan patients. These results demonstrate the high prevalence of H. pylori in the esophagus, and its presence was correlated with signs of inflammation.

Cox2 and β-catenin/T-cell factor signaling intestinalize human esophageal keratinocytes when cultured under organotypic conditions

The incidence of esophageal adenocarcinoma (EAC) is rising in the United States. An important risk factor for EAC is the presence of Barrett esophagus (BE). BE is the replacement of normal squamous esophageal epithelium with a specialized columnar epithelium in response to chronic acid and bile reflux. However, the emergence of BE from squamous keratinocytes has not yet been demonstrated. Our research has focused on this. Wnt and cyclooxygenase 2 (Cox2) are two pathways whose activation has been associated with BE and progression to EAC, but their role has not been tested experimentally. To explore their contribution, we engineered a human esophageal keratinocyte cell line to express either a dominant-active Wnt effector CatCLef or a Cox2 complementary DNA. In a two-dimensional culture environment, Cox2 expression increases cell proliferation and migration, but neither transgene induces known BE markers. In contrast, when these cells were placed into three-dimensional organotypic culture conditions, we observed more profound effects. CatCLef-expressing cells were more proliferative, developed a thicker epithelium, and upregulated Notch signaling and several BE markers including NHE2. Cox2 expression also increased cell proliferation and induced a thicker epithelium. More importantly, we observed cysts form within the epithelium, filled with intestinal mucins including Muc5B and Muc17. This suggests that Cox2 expression in a three-dimensional culture environment induces a lineage of mucin-secreting cells and supports an important causal role for Cox2 in BE pathogenesis. We conclude that in vitro modeling of BE pathogenesis can be improved by enhancing Wnt signaling and Cox2 activity and using three-dimensional organotypic culture conditions.

Regulation of the gene encoding the intestinal bile acid transporter ASBT by the caudal-type homeobox proteins CDX1 and CDX2

The apical sodium-dependent bile acid transporter (ASBT) is expressed abundantly in the ileum and mediates bile acid absorption across the apical membranes. Caudal-type homeobox proteins CDX1 and CDX2 are transcription factors that regulate genes involved in intestinal epithelial differentiation and proliferation. Aberrant expression of both ASBT and CDXs in Barrett's esophagus (BE) prompted us to study, whether the expression of the ASBT gene is regulated by CDXs. Short interfering RNA-mediated knockdown of CDXs resulted in reduced ASBT mRNA expression in intestinal cells. CDXs strongly induced the activity of the ASBT promoter in reporter assays in esophageal and intestinal cells. Nine CDX binding sites were predicted in silico within the ASBT promoter, and binding of CDXs to six of them was verified in vitro and within living cells by electrophoretic mobility shift assays and chromatin immunoprecipitation assays, respectively. RNAs were extracted from esophageal biopsies from 20 BE patients and analyzed by real-time PCR. Correlation with ASBT expression was found for CDX1, CDX2, and HNF-1α in BE biopsies. In conclusion, the human ASBT promoter is activated transcriptionally by CDX1 and CDX2. Our finding provides a possible explanation for the reported observation that ASBT is aberrantly expressed in esophageal metaplasia that also expresses CDX transcription factors.

Molecular mechanisms of Barrett's esophagus

Barrett's esophagus (BE) is defined as the metaplastic conversion of esophageal squamous epithelium to intestinalized columnar epithelium. As a premalignant lesion of esophageal adenocarcinoma (EAC), BE develops as a result of chronic gastroesophageal reflux disease (GERD). Many studies have been conducted to understand the molecular mechanisms of this disease. This review summarizes recent results involving squamous and intestinal transcription factors, signaling pathways, stromal factors, microRNAs, and other factors in the development of BE. A conceptual framework is proposed to guide future studies. We expect elucidation of the molecular mechanisms of BE to help in the development of improved management of GERD, BE, and EAC.

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.