Defining the contribution of Troy-positive progenitor cells to the mouse esophageal epithelium

Progenitor cells adapt their behavior in response to tissue demands. However, the molecular mechanisms controlling esophageal progenitor decisions remain largely unknown. Here, we demonstrate the presence of a Troy (Tnfrsf19)-expressing progenitor subpopulation localized to defined regions along the mouse esophageal axis. Lineage tracing and mathematical modeling demonstrate that Troy-positive progenitor cells are prone to undergoing symmetrical fate choices and contribute to esophageal tissue homeostasis long term. Functionally, TROY inhibits progenitor proliferation and enables commitment to differentiation without affecting fate symmetry. Whereas Troy expression is stable during esophageal homeostasis, progenitor cells downregulate Troy in response to tissue stress, enabling proliferative expansion of basal cells refractory to differentiation and reestablishment of tissue homeostasis. Our results demonstrate functional, spatially restricted progenitor heterogeneity in the esophageal epithelium and identify how dynamic regulation of Troy coordinates tissue generation.

Desmoplakin and periplakin genetically and functionally contribute to eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory disease with a complex underlying genetic etiology. Herein, we conduct whole-exome sequencing of a multigeneration EoE pedigree (discovery set) and 61 additional multiplex families with EoE (replication set). A series of rare, heterozygous, missense variants are identified in the genes encoding the desmosome-associated proteins DSP and PPL in 21% of the multiplex families. Esophageal biopsies from patients with these variants retain dilated intercellular spaces and decrease DSP and PPL expression even during disease remission. These variants affect barrier integrity, cell motility and RhoGTPase activity in esophageal epithelial cells and have increased susceptibility to calpain-14-mediated degradation. An acquired loss of esophageal DSP and PPL is present in non-familial EoE. Taken together, herein, we uncover a pathogenic role for desmosomal dysfunction in EoE, providing a deeper mechanistic understanding of tissue-specific allergic responses.

Isolation of primary immune cells from fibrotic skin, esophageal, and gut tissue

Understanding the interplay between immune and structural cells is important for studying fibrosis and inflammation; however, primary immune cell isolation from organs that are typically enriched in stromal cells, like the lung, esophagus, or gut, proves to be an ongoing challenge. In fibrotic conditions, this challenge becomes even greater as infiltrating cells become trapped in the robust extracellular matrix (ECM). This protocol details a method to isolate cells at high yield from stroma-rich organs that can be used for further analyses via flow cytometry, stimulation, or culturing. Validation of this method is confirmed by flow cytometry data assessing immune cell populations of interest. This protocol can be completed in approximately 5-6 h.

Notch Signaling Mediates Differentiation in Barrett's Esophagus and Promotes Progression to Adenocarcinoma

BACKGROUND & AIMS

Studies are needed to determine the mechanism by which Barrett's esophagus (BE) progresses to esophageal adenocarcinoma (EAC). Notch signaling maintains stem cells in the gastrointestinal tract and is dysregulated during carcinogenesis. We explored the relationship between Notch signaling and goblet cell maturation, a feature of BE, during EAC pathogenesis.

METHODS

We measured goblet cell density and levels of Notch messenger RNAs in BE tissues from 164 patients, with and without dysplasia or EAC, enrolled in a multicenter study. We analyzed the effects of conditional expression of an activated form of NOTCH2 (pL2.Lgr5.N2IC), conditional deletion of NOTCH2 (pL2.Lgr5.N2fl/fl), or loss of nuclear factor κB (NF-κB) (pL2.Lgr5.p65fl/fl), in Lgr5+ (progenitor) cells in L2-IL1B mice (which overexpress interleukin 1 beta in esophagus and squamous forestomach and are used as a model of BE). We collected esophageal and stomach tissues and performed histology, immunohistochemistry, flow cytometry, transcriptome, and real-time polymerase chain reaction analyses. Cardia and forestomach tissues from mice were cultured as organoids and incubated with inhibitors of Notch or NF-kB.

RESULTS

Progression of BE to EAC was associated with a significant reduction in goblet cell density comparing nondysplastic regions of tissues from patients; there was an inverse correlation between goblet cell density and levels of NOTCH3 and JAG2 messenger RNA. In mice, expression of the activated intracellular form of NOTCH2 in Lgr5+ cells reduced goblet-like cell maturation, increased crypt fission, and accelerated the development of tumors in the squamocolumnar junction. Mice with deletion of NOTCH2 from Lgr5+ cells had increased maturation of goblet-like cells, reduced crypt fission, and developed fewer tumors. Esophageal tissues from in pL2.Lgr5.N2IC mice had increased levels of RelA (which encodes the p65 unit of NF-κB) compared to tissues from L2-IL1B mice, and we found evidence of increased NF-κB activity in Lgr5+ cells. Esophageal tissues from pL2.Lgr5.p65fl/fl mice had lower inflammation and metaplasia scores than pL2.Lgr5.N2IC mice. In organoids derived from pL2-IL1B mice, the NF-κB inhibitor JSH-23 reduced cell survival and proliferation.

CONCLUSIONS

Notch signaling contributes to activation of NF-κB and regulates differentiation of gastric cardia progenitor cells in a mouse model of BE. In human esophageal tissues, progression of BE to EAC was associated with reduced goblet cell density and increased levels of Notch expression. Strategies to block this pathway might be developed to prevent EAC in patients with BE.

Deletion of TRPV4 enhances in vitro wound healing of murine esophageal keratinocytes

Transient receptor potential vanilloid 4 (TRPV4) is a non-selective cation channel that is widely expressed in different body tissues and plays several physiological roles. This channel is highly expressed in esophageal keratinocytes where its activation mediates ATP release. However, whether TRPV4 has a role in wound healing of esophageal keratinocytes is unclear. In this study, we demonstrated that both cell migration and proliferation were slower in wild-type esophageal keratinocytes compared to cells having TRPV4 knockout. Our results suggest that TRPV4-mediated release of ATP from esophageal keratinocytes contributes to a decrease in the rate of in vitro wound healing via the ATP degradation product adenosine, which acts on A2B adenosine receptors.

Eosinophilic esophagitis: Current concepts in diagnosis and treatment

Eosinophilic esophagitis is an immune-allergic pathology of multifactorial etiology (genetic and environmental) that affects both pediatric and adult patients. Its symptoms, which include heartburn, regurgitation, and esophageal stenosis (with dysphagia being more frequent in eosinophilic esophagitis in young adults and children), are similar to those of gastroesophageal reflux disease, causing delays in diagnosis and treatment. Although endoscopic findings such as furrows, esophageal mucosa trachealization, and whitish exudates may suggest its presence, this diagnosis should be confirmed histologically based on the presence of more than 15 eosinophils per high-power field and the exclusion of other causes of eosinophilia (parasitic infections, hypereosinophilic syndrome, inflammatory bowel disease, among others) for which treatment could be initiated. Currently, the 3 “D”s (“Drugs, Diet, and Dilation”) are considered the fundamental components of treatment. The first 2 components, which involve the use of proton pump inhibitors, corticosteroids, immunosuppressants and empirical diets or guided food elimination based on allergy tests, are more useful in the initial phases, whereas endoscopic dilation is reserved for esophageal strictures. Herein, the most important aspects of eosinophilic esophagitis pathophysiology will be reviewed, in addition to evidence for the various treatments.

Somatic mutation and clonal expansions in human tissues

Recent sequencing studies on healthy skin and esophagus have found that, as we age, these tissues become colonized by mutant clones of cells carrying driver mutations in traditional cancer genes. This comment summarizes these findings and discusses their possible implications for our understanding of cancer, ageing, and other diseases.

Noncoding RNAs as drivers of the phenotypic plasticity of oesophageal mucosa

The histological commitment of the lower oesophageal mucosa largely depends on a complex molecular landscape. After extended inflammatory insult due to gastroesophageal reflux disease, squamous oesophageal mucosa may differentiate into columnar metaplastic mucosa. In this setting, the presence of intestinal metaplasia is considered the starting point of Barrett’s carcinogenetic cascade. Aside from secondary prevention strategies for Barrett’s mucosa (BM) patients, there are multiple endoscopic ablative therapies available for BM eradication and for the replacement of metaplastic epithelia with a neosquamous mucosa. However, BM frequently recurs in a few years, which supports the notable phenotypic plasticity of the oesophageal mucosa. In recent years, several reports pinpointed a class of small noncoding RNAs, the microRNAs (miRNAs), as principal effectors and regulators of oesophageal mucosa metaplastic (and neoplastic) transformation. Because of miRNAs notable stability in fixed archival diagnostic specimens, expression profiling of miRNAs represent an innovative diagnostic, prognostic and predictive tool in the stratification of phenotypic alterations in the oesophageal mucosa.