Structural alterations of the mucosa stroma in the Barrett's esophagus metaplasia-dysplasia-adenocarcinoma sequence

Engineered hydrogel reveals contribution of matrix mechanics to esophageal adenocarcinoma and identifies matrix-activated therapeutic targets

Increased extracellular matrix (ECM) stiffness has been implicated in esophageal adenocarcinoma (EAC) progression, metastasis, and resistance to therapy. However, the underlying protumorigenic pathways are yet to be defined. Additional work is needed to develop physiologically relevant in vitro 3D culture models that better recapitulate the human tumor microenvironment and can be used to dissect the contributions of matrix stiffness to EAC pathogenesis. Here, we describe a modular, tumor ECM-mimetic hydrogel platform with tunable mechanical properties, defined presentation of cell-adhesive ligands, and protease-dependent degradation that supports robust in vitro growth and expansion of patient-derived EAC 3D organoids (EAC PDOs). Hydrogel mechanical properties control EAC PDO formation, growth, proliferation, and activation of tumor-associated pathways that elicit stem-like properties in the cancer cells, as highlighted through in vitro and in vivo environments. We also demonstrate that the engineered hydrogel serves as a platform for identifying potential therapeutic targets to disrupt the contribution of protumorigenic matrix mechanics in EAC. Together, these studies show that an engineered PDO culture platform can be used to elucidate underlying matrix-mediated mechanisms of EAC and inform the development of therapeutics that target ECM stiffness in EAC.

Esophageal extracellular matrix hydrogel mitigates metaplastic change in a dog model of Barrett's esophagus

Chronic inflammatory gastric reflux alters the esophageal microenvironment and induces metaplastic transformation of the epithelium, a precancerous condition termed Barrett's esophagus (BE). The microenvironmental niche, which includes the extracellular matrix (ECM), substantially influences cell phenotype. ECM harvested from normal porcine esophageal mucosa (eECM) was formulated as a mucoadhesive hydrogel, and shown to largely retain basement membrane and matrix-cell adhesion proteins. Dogs with BE were treated orally with eECM hydrogel and omeprazole (n = 6) or omeprazole alone (n = 2) for 30 days. eECM treatment resolved esophagitis, reverted metaplasia to a normal, squamous epithelium in four of six animals, and downregulated the pro-inflammatory tumor necrosis factor-α+ cell infiltrate compared to control animals. The metaplastic tissue in control animals (n = 2) did not regress. The results suggest that in vivo alteration of the microenvironment with a site-appropriate, mucoadhesive ECM hydrogel can mitigate the inflammatory and metaplastic response in a dog model of BE.

Human esophageal myofibroblasts secrete proinflammatory cytokines in response to acid and Toll-like receptor 4 ligands

The pathophysiology of esophageal injury, repair, and inflammation in gastroesophageal reflux-disease (GERD) is complex. Whereas most studies have focused on the epithelial response to GERD injury, we are interested in the stromal response. We hypothesized that subepithelial esophageal myofibroblasts in GERD secrete proinflammatory cytokines in response to injurious agents encountered via epithelial barrier breaches or through dilated epithelial intercellular spaces. We determined the percentage of myofibroblasts [-smooth muscle actin (-SMA)+vimentin+CD31-] in the subepithelial GERD and normal esophageal stroma by immunomorphologic analysis. We performed -SMA coimmunostaining with IL-6 and p65. We established and characterized primary cultures of -SMA+vimentin+CD31-CD45- human esophageal myofibroblasts (HuEso MFs). We modeled GERD by treatment with pH 4.5-acidified media and Toll-like receptor 4 (TLR4) ligands, LPS and high-mobility group box 1 protein (HMGB1), and determined myofibroblast cytokine secretion in response to GERD injury. We demonstrate that spindle-shaped cell myofibroblasts are located near the basement membrane of stratified squamous epithelium in normal esophagus. We identify an increase in subepithelial myofibroblasts and activation of proinflammatory pathways in patients with GERD. Primary cultures of stromal cells obtained from normal esophagus retain myofibroblast morphology and express the acid receptor transient receptor potential channel vanilloid subfamily 1 (TRPV1) and TLR4. HuEso MFs stimulated with acid and TLR4 agonists LPS and HMGB1 increase IL-6 and IL-8 secretion via TRPV1 and NF-B activation. Our work implicates a role for human subepithelial stromal cells in the pathogenesis of GERD-related esophageal injury. Findings of this study can be extended to the investigation of epithelial-stromal interactions in inflammatory esophageal mucosal disorders.

Telocytes in human oesophagus

Telocytes (TCs), a new type of interstitial cells, were identified in many different organs and tissues of mammalians and humans. In this study, we show the presence, in human oesophagus, of cells having the typical features of TCs in lamina propria of the mucosa, as well as in muscular layers. We used transmission electron microscopy (TEM), immunohistochemistry (IHC) and primary cell culture. Human oesophageal TCs present a small cell body with 2–3 very long Telopodes (Tps). Tps consist of an alternation of thin segments (podomers) and thick segments (podoms) and have a labyrinthine spatial arrangement. Tps establish close contacts (‘stromal synapses’) with other neighbouring cells (e.g. lymphocytes, macrophages). The ELISA testing of the supernatant of primary culture of TCs indicated that the concentrations of VEGF and EGF increased progressively. In conclusion, our study shows the existence of typical TCs at the level of oesophagus (mucosa, submucosa and muscular layer) and suggests their possible role in tissue repair.

Investigation of the esophageal Rho-kinase expression in patients with Barrett's esophagus

The mechanisms responsible for the malignant transformation in Barrett's esophagus (BE) are still poorly understood. The authors have evaluated the role of Rho-kinase (ROCK1 and ROCK2) expressions in patients with BE. All patients underwent upper gastrointestinal system endoscopy, which was confirmed histologically. Real-time PCR revealed no marked change in gene expressions of ROCK1 and ROCK2 at mRNA levels in BE when compared to controls. Immunohistochemical and western blot analyses showed no change in ROCK1 and ROCK2 protein expressions in BE. This study demonstrates that Rho-kinase gene and protein expressions are not modified in BE.

Management strategies of Barrett's esophagus

Barrett’s esophagus is a condition resulting from chronic gastro-esophageal reflux disease with a documented risk of esophageal adenocarcinoma. Current strategies for improved survival in patients with Barrett's adenocarcinoma focus on detection of dysplasia. This can be obtained by screening programs in high-risk cohorts of patients and/or endoscopic biopsy surveillance of patients with known Barrett’s esophagus (BE). Several therapies have been developed in attempts to reverse BE and reduce cancer risk. Aggressive medical management of acid reflux, lifestyle modifications, antireflux surgery, and endoscopic treatments have been recommended for many patients with BE. Whether these interventions are cost-effective or reduce mortality from esophageal cancer remains controversial. Current treatment requires combinations of endoscopic mucosal resection techniques to eliminate visible lesions followed by ablation of residual metaplastic tissue. Esophagectomy is currently indicated in multifocal high-grade neoplasia or mucosal Barrett’s carcinoma which cannot be managed by endoscopic approach.