Squamous tissue lymphocytes in the esophagus of controls and patients with reflux esophagitis and Barrett's esophagus are characterized by a non-inflammatory phenotype

Mucosal neuroimmune mechanisms in gastro-oesophageal reflux disease (GORD) pathogenesis

Gastro-oesophageal reflux disease (GORD) is a chronic condition characterised by visceral pain in the distal oesophagus. The current first-line treatment for GORD is proton pump inhibitors (PPIs), however, PPIs are ineffective in a large cohort of patients and long-term use may have adverse effects. Emerging evidence suggests that nerve fibre number and location are likely to play interrelated roles in nociception in the oesophagus of GORD patients. Simultaneously, alterations in cells of the oesophageal mucosa, namely epithelial cells, mast cells, dendritic cells, and T lymphocytes, have been a focus of GORD research for several years. The oesophagus of GORD patients exhibits both macro- and micro-inflammation as a response to chronic acidic reflux at the epithelium. In other conditions of the GI tract, such as IBS and IBD, well-characterised bidirectional processes between immune cells and mucosal nerve fibres contribute to pathogenesis and symptom generation. Sensory alterations in these conditions such as nerve fibre outgrowth and hypersensitivity can be driven by inflammatory processes, which promote visceral pain signalling. This review will examine what is currently known of the molecular pathways linking inflammation and sensory perception leading to the development of GORD symptoms and explore potentially relevant mechanisms in other GI regions which may indicate new areas in GORD research.

Promises and Limitations of Current Models for Understanding Barrett's Esophagus and Esophageal Adenocarcinoma

BACKGROUND & AIMS

This review was developed to provide a thorough and effective update on models relevant to esophageal metaplasia, dysplasia, and carcinogenesis, focusing on the advantages and limitations of different models of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC).

METHODS

This expert review was written on the basis of a thorough review of the literature combined with expert interpretation of the state of the field. We emphasized advances over the years 2012-2023 and provided detailed information related to the characterization of established human esophageal cell lines.

RESULTS

New insights have been gained into the pathogenesis of BE and EAC using patient-derived samples and single-cell approaches. Relevant animal models include genetic as well as surgical mouse models and emphasize the development of lesions at the squamocolumnar junction in the mouse stomach. Rat models are generated using surgical approaches that directly connect the small intestine and esophagus. Large animal models have the advantage of including features in human esophagus such as esophageal submucosal glands. Alternatively, cell culture approaches remain important in the field and allow for personalized approaches, and scientific rigor can be ensured by authentication of cell lines.

CONCLUSIONS

Research in BE and EAC remains highly relevant given the morbidity and mortality associated with cancers of the tubular esophagus and gastroesophageal junction. Careful selection of models and inclusion of human samples whenever possible will ensure relevance to human health and disease.

Mechanisms and pathophysiology of Barrett oesophagus

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

Dynamic switch of immunity and antitumor effects of metformin in rat spontaneous esophageal carcinogenesis

Chronic inflammation contributes to tumor development by creating a local microenvironment that facilitates neoplastic transformation and potentiates the progression of cancer. Esophageal cancer (EC) is an inflammation-associated malignancy with a poor prognosis. The nature of the switch between chronic inflammation of the esophagus and EC-related immunological changes remains unclear. Here, we examined the dynamic alterations of immune cells at different stages of chronic esophagitis, Barrett’s esophagus (BE) and EC using an esophageal spontaneous carcinogenesis rat model. We also investigated the anticancer effects of metformin. To stimulate EC carcinogenesis, chronic gastroduodenal reflux esophagitis via esophagojejunostomy was induced in 120 rats in metformin-treated and non-treated (control) groups. After 40 weeks, BE and EC developed in 96.7% and 63.3% of the control group, and in 66.7% and 23.3% of the metformin-treated group, respectively. Flow cytometric analysis demonstrated that the balance of M1/M2-polarized or phospho-Stat3-positive macrophages, regulatory T, cytotoxic T, natural killer (NK), NK T cells, and Th17 T cells was dynamically changed at each stage of the disease and were resolved by metformin treatment. These findings clarify the immunity in esophageal carcinogenesis and suggest that metformin could suppress this disease by improving the immunosuppressive tumor microenvironment and immune evasion.

Esophageal mucosa in HIV infection: A"deeper" look at this little spoken organ

BACKGROUND AND AIM

Although the esophagus is a common site of opportunistic infection in AIDS patients, little is known about the impact of HIV as well as opportunistic infection in the esophageal mucosa. Our aim is to analyze the esophageal immune profile in HIV+ patients with different immunological status with and without the opportunistic Candida infection.

METHODS

Immunohistochemistry to CD4⁺ and CD8⁺ T-cells, γ-interferon, transforming growth factor-β, interleukin (IL)-4, IL-6, IL-13, and IL-17 was performed in esophageal samples of 40 chronically HIV+ patients under highly active antiretroviral therapy (16 with Candida esophagitis, 12 virologically non-supressed with blood CD4 count < 500, and 12 virologically suppressed with blood CD4 count > 500; the latter two groups without esophageal candidiasis). The controls were 12 HIV-negative healthy individuals.

RESULTS

Esophageal CD4⁺ T-cell expression in HIV+ patients did not differ from the control group (P = 0.50). Mucosal CD8⁺ T-cell expression was significantly increased in HIV+ patients (P = 0.0018). Candida esophagitis and virologically non-supressed HIV+ patients with CD4 < 500 showed an increased expression of IL-17 and IL-6 with fewer expressions of γ-interferon, more attenuated in the latter group. Transforming growth factor-β was increased only in virologically suppressed HIV+ patients with CD4 > 500. IL-4 and IL-13 were similar to the control group.

CONCLUSION

In contrast to CD8⁺ T-cell expression, esophageal CD4⁺ T-cell expression does not reflect the HIV+ patient's immunological status. T-helper 17 (Th17) response seems to play a role in the esophageal mucosa of virologically non-supressed HIV+ patients with blood CD4 < 500. Candida esophagitis showed a Th1/Th17 response but seems to be dominantly regulated by the Th17 pathway.

Post-ablation lymphocytic esophagitis in Barrett esophagus with high grade dysplasia or intramucosal carcinoma

In patients who have undergone ablation therapy for treatment of Barrett's esophagus with dysplasia, histologic features of eosinophilic esophagitis, but not lymphocytic esophagitis, have been described. We evaluated for histologic evidence of eosinophilic esophagitis and lymphocytic esophagitis and correlated with endoscopic findings in this population. A single-institution Barrett's esophagus registry was searched for patients who had received radiofrequency ablation, cryotherapy, or both for treatment of Barrett's esophagus with dysplasia. Clinical and endoscopic data were collected and biopsies were reviewed for inflammation and reactive changes at three time points: pre-intervention, first surveillance after ablation therapy, and most recent surveillance. Of the 173 patients initially identified, 102 met the inclusion criteria. Intraepithelial eosinophils were increased at first surveillance (60%, P=0.096) and last surveillance (69%, P=0.048) compared with pre-intervention (50%), although histologic evidence of post-ablation eosinophilic esophagitis was not significant. Prevalence of lymphocytic esophagitis was significantly higher at first surveillance (17%, P=0.02) and at last surveillance (43%, P<0.001), compared with pre-intervention (7%). Smoking, hyperlipidemia, and cryotherapy were identified as independent risk factors for developing histologic lymphocytic esophagitis. This is the first report that histologic evidence of lymphocytic esophagitis increased over time in patients undergoing ablation for Barrett's esophagus with dysplasia. Though the pathophysiology of lymphocytic esophagitis remains unknown, patients in our study with a history of smoking, hyperlipidemia, or cryotherapy were more likely to develop post-ablation lymphocytic esophagitis.

Rebamipide Alters the Esophageal Microbiome and Reduces the Incidence of Barrett's Esophagus in a Rat Model

BACKGROUND

Barrett's esophagus (BE) is characterized by a distinct Th2-predominant cytokine profile. However, antigens that shift the immune response toward the Th2 profile are unknown.

AIM

We examined the effects of rebamipide on the esophageal microbiome and BE development in a rat model.

METHODS

BE was induced by esophagojejunostomy in 8-week-old male Wistar rats. Rats were divided into control and rebamipide-treated group receiving either a normal or a 0.225 % rebamipide-containing diet, respectively, and killed 8, 16, 24, and 32 weeks after the operation. PCR-amplified 16S rDNAs extracted from esophageal samples were examined by terminal-restriction fragment length polymorphism (T-RFLP) analysis to assess microbiome composition. The dynamics of four bacterial genera (Lactobacillus, Clostridium, Streptococcus, and Enterococcus) were analyzed by real-time PCR.

RESULTS

The incidences of BE in the control and rebamipide group at 24 and 32 weeks were 80 and 100, and 20 and 33 %, respectively. T-RFLP analysis of normal esophagus revealed that the proportion of Clostridium was 8.3 %, while that of Lactobacillales was 71.8 %. The proportions of Clostridium increased and that of Lactobacillales decreased at 8 weeks in both groups. Such changes were consistently observed in the control but not in the rebamipide group. Clostridium and Lactobacillus expression was lower and higher, respectively, in the rebamipide group than in the control group.

CONCLUSIONS

Rebamipide reduced BE development and altered the esophageal microbiome composition, which might play a role in BE development.

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.