Effects of topical steroids on tight junction proteins and spongiosis in esophageal epithelia of patients with eosinophilic esophagitis

Exploring the Impact of Gender on the Characteristics and Complications of Eosinophilic Esophagitis

Background

Eosinophilic esophagitis (EoE) is a chronic inflammatory process of the esophagus often associated with structural and motility problems. Previous studies have shown an increased prevalence in males over females, however there is little data exploring the risk of esophageal complications among genders, which may be indicative of differences in disease severity.

Methods

This is a retrospective cohort study using National Inpatient Sample data including adults hospitalized between 2016 and 2020 presenting with EoE. The primary outcome measured was inpatient complications related to the patient's history of EoE and secondary outcomes include demographics, comorbidities, month of presentation, and age of patients.

Results

Of the 21 755 patients with history of EoE, 112 260 (52%) were male and 10 495 (48%) were female. Males had higher rates of several EoE complications, including esophageal obstruction, food bolus, esophageal rupture, requiring esophageal dilation, requiring esophageal laceration repair with p < 0.05 for all. Higher rates of females with EoE were seen in the Black population (p < 0.05). We also found that males were most likely to have esophageal impaction and esophageal rupture in the month of March (p < 0.05). Esophageal impaction was more common in males ages 25-29 (p < 0.05), whereas females were more likely from age 75-79 (p < 0.05).

Conclusion

Males have an overall high rate of complication from EoE. There was a higher prevalence of females with EoE in the Black population although the rates of complication remained higher in males in this subpopulation. The month of March carries a risk of esophageal impaction and rupture pronounced particularly in men. Age also appears to have an influence on the rate of esophageal impaction.

Eosinophilic Esophagitis: What the Otolaryngologist Needs to Know

Eosinophilic esophagitis is a male-predominant disease with presentations ranging from nonspecific feeding issues to dysphagia and food impaction. The currently proposed pathophysiology is a combination of genetics, allergens, and epithelial barrier impairment. Diagnosis is reliant on history, endoscopic examination, and biopsy. Recent guidelines recognize the role of concurrent gastroesophageal reflux disease. Treatment is based on 3 paradigms: diet, drugs, and dilation. Drug therapy has historically focused on topical corticosteroids; as of 2022, dupilumab was approved for targeted biologic therapy. Dilation is reserved for symptomatic and anatomic management. As this clinical entity is better understood, additional therapies will hopefully be developed.

Lysyl Oxidase Regulates Epithelial Differentiation and Barrier Integrity in Eosinophilic Esophagitis

BACKGROUND & AIMS

Epithelial disruption in eosinophilic esophagitis (EoE) encompasses both impaired differentiation and diminished barrier integrity. We have shown that lysyl oxidase (LOX), a collagen cross-linking enzyme, is up-regulated in the esophageal epithelium in EoE. However, the functional roles of LOX in the esophageal epithelium remains unknown.

METHODS

We investigated roles for LOX in the human esophageal epithelium using 3-dimensional organoid and air-liquid interface cultures stimulated with interleukin (IL)13 to recapitulate the EoE inflammatory milieu, followed by single-cell RNA sequencing, quantitative reverse-transcription polymerase chain reaction, Western blot, histology, and functional analyses of barrier integrity.

RESULTS

Single-cell RNA sequencing analysis on patient-derived organoids revealed that LOX was induced by IL13 in differentiated cells. LOX-overexpressing organoids showed suppressed basal and up-regulated differentiation markers. In addition, LOX overexpression enhanced junctional protein genes and transepithelial electrical resistance. LOX overexpression restored the impaired differentiation and barrier function, including in the setting of IL13 stimulation. Transcriptome analyses on LOX-overexpressing organoids identified an enriched bone morphogenetic protein (BMP) signaling pathway compared with wild-type organoids. In particular, LOX overexpression increased BMP2 and decreased the BMP antagonist follistatin. Finally, we found that BMP2 treatment restored the balance of basal and differentiated cells.

CONCLUSIONS

Our data support a model whereby LOX exhibits noncanonical roles as a signaling molecule important for epithelial homeostasis in the setting of inflammation via activation of the BMP pathway in the esophagus. The LOX/BMP axis may be integral in esophageal epithelial differentiation and a promising target for future therapies.

The Role of Esophageal Physiologic Tests in Eosinophilic Esophagitis

Background

In patients with eosinophilic esophagitis (EoE), the correlation between symptoms of esophageal dysfunction and endoscopic and histologic disease activity is generally poor and probably related to multiple causes such as esophageal remodeling processes that might go undetected using endoscopy and histology as well as esophageal hypervigilance and symptom-specific anxiety. Hence, there is a need for a holistic management of patients that goes beyond the control of eosinophilia and symptoms.

Summary and Key Messages

Physiological esophageal testing using high-resolution manometry, functional lumen imaging probe, pH-impedance, wireless pH monitoring, and mucosal impedance may unveil the effects of chronic transmural fibro-inflammatory changes of the esophageal wall as well as esophageal hypervigilance, thereby assisting to phenotype patients, predict therapeutic response to therapy, and identify motility disorders that may need a specific targeted therapy to ameliorate patients' outcomes. This article discusses the role of functional esophageal examinations in the diagnosis and management of EoE.

Hypoxia-inducible microRNA-155 negatively regulates epithelial barrier in eosinophilic esophagitis by suppressing tight junction claudin-7

MicroRNA (miRNA)-mediated mRNA regulation directs many homeostatic and pathological processes, but how miRNAs coordinate aberrant esophageal inflammation during eosinophilic esophagitis (EoE) is poorly understood. Here, we report a deregulatory axis where microRNA-155 (miR-155) regulates epithelial barrier dysfunction by selectively constraining tight junction CLDN7 (claudin-7). MiR-155 is elevated in the esophageal epithelium of biopsies from patients with active EoE and in cell culture models. MiR-155 localization using in situ hybridization (ISH) in patient biopsies and intra-epithelial compartmentalization of miR-155 show expression predominantly within the basal epithelia. Epithelial miR-155 activity was evident through diminished target gene expression in 3D organotypic cultures, particularly in relatively undifferentiated basal cell states. Mechanistically, generation of a novel cell line with enhanced epithelial miR-155 stable overexpression induced a functionally deficient epithelial barrier in 3D air-liquid interface epithelial cultures measured by transepithelial electrical resistance (TEER). Histological assessment of 3D esophageal organoid cultures overexpressing miR-155 showed notable dilated intra-epithelial spaces. Unbiased RNA-sequencing analysis and immunofluorescence determined a defect in epithelial barrier tight junctions and revealed a selective reduction in the expression of critical esophageal tight junction molecule, claudin-7. Together, our data reveal a previously unappreciated role for miR-155 in mediating epithelial barrier dysfunction in esophageal inflammation.

Barrier Dysfunction in Eosinophilic Esophagitis

PURPOSE OF REVIEW

Compelling evidence over the past decade supports the central role of epithelial barrier dysfunction in the pathophysiology of eosinophilic esophagitis (EoE). The purpose of this review is to summarize the genetic, environmental, and immunologic factors driving epithelial barrier dysfunction, and how this impaired barrier can further promote the inflammatory response in EoE.

RECENT FINDINGS

Common environmental exposures, such as detergents, may have a direct impact on the esophageal epithelial barrier. In addition, the effects of IL-13 on barrier dysfunction may be reduced by 17β-estradiol, Vitamin D, and the short chain fatty acids butyrate and propionate, suggesting novel therapeutic targets. There are many genetic, environmental, and immunologic factors that contribute to epithelial barrier dysfunction in EoE. This leads to further skewing of the immune response to a "Th2" phenotype, alterations in the esophageal microbiome, and penetration of relevant antigens into the esophageal mucosa, which are central to the pathophysiology of EoE.

Mechanistic Insights into Eosinophilic Esophagitis: Therapies Targeting Pathophysiological Mechanisms

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease characterized by eosinophilic infiltration of the esophagus. It arises from a complex interplay of genetic predisposition (susceptibility loci), environmental triggers (allergens and dietary antigens), and a dysregulated immune response, mainly mediated by type 2 T helper cell (Th2)-released cytokines, such as interleukin (IL)-4, IL-5, and IL-13. These cytokines control eosinophil recruitment and activation as well as tissue remodeling, contributing to the characteristic features of EoE. The pathogenesis of EoE includes epithelial barrier dysfunction, mast cell activation, eosinophil degranulation, and fibrosis. Epithelial barrier dysfunction allows allergen penetration and promotes immune cell infiltration, thereby perpetuating the inflammatory response. Mast cells release proinflammatory mediators and promote eosinophil recruitment and the release of cytotoxic proteins and cytokines, causing tissue damage and remodeling. Prolonged inflammation can lead to fibrosis, resulting in long-term complications such as strictures and dysmotility. Current treatment options for EoE are limited and mainly focus on dietary changes, proton-pump inhibitors, and topical corticosteroids. Novel therapies targeting key inflammatory pathways, such as monoclonal antibodies against IL-4, IL-5, and IL-13, are emerging in clinical trials. A deeper understanding of the complex pathogenetic mechanisms behind EoE will contribute to the development of more effective and personalized therapeutic strategies.

Barrett's Esophagus in Eosinophilic Esophagitis in Swiss Eosinophilic Esophagitis Cohort Study (SEECS)

INTRODUCTION

There is a complex interrelationship between gastroesophageal reflux disease (GERD) and eosinophilic esophagitis (EoE) potentially promoting the occurrence and modulating severity of each other reciprocally. Presence of Barrett's esophagus (BE) is a defining factor for the diagnosis of GERD. While several studies investigated the potential impact of concomitant GERD on the presentation and course of EoE, little was known with regards to BE in EoE patients.

METHODS

We analyzed prospectively collected clinical, endoscopic, and histological data from patients enrolled in the Swiss Eosinophilic Esophagitis Cohort Study (SEECS) regarding differences between EoE patients with (EoE/BE+) versus without BE (EoE/BE-) and determined the prevalence of BE in EoE patients.

RESULTS

Among a total of 509 EoE patients included in our analysis, 24 (4.7%) had concomitant BE with a high male preponderance (EoE/BE+ 83.3% vs. EoE/BE- 74.4%). While there were no differences in dysphagia, odynophagia was significantly (12.5 vs. 3.1%, p = 0.047) more common in EoE/BE+ versus EoE/BE-. General well-being at last follow-up was significantly lower in EoE/BE+. Endoscopically, we observed an increased incidence of fixed rings in the proximal esophagus in EoE/BE+ (70.8 vs. 46.3% in EoE/BE-, p = 0.019) and a higher fraction of patients with a severe fibrosis in the proximal histological specimen (8.7 vs. 1.6% in EoE/BE, p = 0.017).

CONCLUSION

Our study reveals that BE is twice as frequent in EoE patients compared to general population. Despite many similarities between EoE patients with and without BE, the finding of a more pronounced remodeling in EoE patients with Barrett is noteworthy.

Lysyl oxidase regulates epithelial differentiation and barrier integrity in eosinophilic esophagitis

Background & Aims

Epithelial disruption in eosinophilic esophagitis (EoE) encompasses both impaired differentiation and diminished barrier integrity. We have shown that lysyl oxidase (LOX), a collagen cross-linking enzyme, is upregulated in the esophageal epithelium in EoE. However, the functional roles of LOX in the esophageal epithelium remains unknown.

Methods

We investigated roles for LOX in the human esophageal epithelium using 3-dimensional organoid and air-liquid interface cultures stimulated with interleukin (IL)-13 to recapitulate the EoE inflammatory milieu, followed by single-cell RNA sequencing, quantitative reverse transcription-polymerase chain reaction, western blot, histology, and functional analyses of barrier integrity.

Results

Single-cell RNA sequencing analysis on patient-derived organoids revealed that LOX was induced by IL-13 in differentiated cells. LOX-overexpressing organoids demonstrated suppressed basal and upregulated differentiation markers. Additionally, LOX overexpression enhanced junctional protein genes and transepithelial electrical resistance. LOX overexpression restored the impaired differentiation and barrier function, including in the setting of IL-13 stimulation. Transcriptome analyses on LOX-overexpressing organoids identified enriched bone morphogenetic protein (BMP) signaling pathway compared to wild type organoids. Particularly, LOX overexpression increased BMP2 and decreased BMP antagonist follistatin. Finally, we found that BMP2 treatment restored the balance of basal and differentiated cells.

Conclusions

Our data support a model whereby LOX exhibits non-canonical roles as a signaling molecule important for epithelial homeostasis in the setting of inflammation via activation of BMP pathway in esophagus. The LOX/BMP axis may be integral in esophageal epithelial differentiation and a promising target for future therapies.

Eosinophilic Esophagitis beyond Eosinophils - an Emerging Phenomenon Overlapping with Eosinophilic Esophagitis: Collegium Internationale Allergologicum (CIA) Update 2023

Having long been considered the mainstay in eosinophilic esophagitis (EoE) diagnosis and pathogenesis, the role of eosinophils has been questioned and might be less important than previously thought. It is well known now that EoE is a Th2-mediated disease with many more disease features than eosinophilic infiltration. With more knowledge on EoE, less pronounced phenotypes or nuances of the disease have become apparent. In fact, EoE might be only the tip of the iceberg (and the most extreme phenotype) with several variant forms, at least three, lying on a disease spectrum. Although a common (food induced) pathogenesis has yet to be confirmed, gastroenterologists and allergologists should be aware of these new phenomena in order to further characterize these patients. In the following review, we discuss the pathogenesis of EoE, particularly those mechanisms beyond eosinophilic infiltration of the esophageal mucosa, non-eosinophilic inflammatory cell populations, the new disease entity EoE-like disease, variant forms of EoE, and the recently coined term mast cell esophagitis.

Mean nocturnal baseline impedance and endoscopic mucosal impedance measurements in patients with eosinophilic esophagitis: a new tool for follow up and management?

Eosinophilic esophagitis (EoE) is the second most common cause of chronic esophageal inflammation after GERD, with increasing incidence and prevalence across all age groups. Since current diagnosis and follow up of EoE require endoscopy with biopsies, there is an increased interest in non or less invasive tests for its diagnosis and follow up. Baseline mucosal impedance measurement allows evaluation of mucosal barrier properties and is widely accepted as an adjunct method in GERD diagnosis. As EoE is associated with increased mucosal permeability, the use of baseline impedance to evaluate mucosal integrity has been investigated in several studies. It was found that baseline mucosal impedance, measured either during 24 h reflux monitoring or during endoscopy, was significantly lower in all parts of the esophagus in EoE patients. Impedance measurement correlated with eosinophil counts on biopsies, offering a tool to monitor treatment response. Additionally, baseline impedance patterns differed between those responding to proton pump inhibitor (PPI) treatment and those resistant to PPI, potentially allowing to tailor future treatment to the individual patient. In summary, baseline impedance measurement offers a potential tool for diagnosis and follow up in EoE. Its exact place in EoE treatment is yet to be determined and requires further future studies.

Eosinophilic esophagitis: Immune mechanisms and therapeutic targets

Eosinophilic esophagitis (EoE) is an emerging chronic inflammatory disease of the oesophagus and is clinically characterized by upper gastrointestinal (GI) symptoms including dysphagia and esophageal food impaction. Histopathologic manifestations, which include intraepithelial eosinophilic inflammation and alterations of the esophageal squamous epithelium, such as basal zone hyperplasia (BZH) and dilated intercellular spaces (DIS), are thought to contribute to esophageal dysfunction and disease symptoms. Corroborative clinical and discovery science-based studies have established that EoE is characterized by an underlying allergic inflammatory response, in part, related to the IL-13/CCL26/eosinophil axis driving dysregulation of several key epithelial barrier and proliferative regulatory genes including kallikrein (KLK) serine proteases, calpain 14 (CAPN14) and anoctamin 1 (ANO1). The contribution of these inflammatory and proliferative processes to the clinical and histological manifestations of disease are not fully elucidated. Herein, we discuss the immune molecules and cells that are thought to underlie the clinical and pathologic manifestations of EoE and the emerging therapeutics targeting these processes for the treatment of EoE.

Trends in gastroesophageal reflux disease research: A bibliometric and visualized study

Background

Gastroesophageal reflux disease (GERD), a disorder resulting from the retrograde flow of gastric contents into the esophagus, affects an estimated 10-30% of the Western population, which is characterized by multifactorial pathogenesis. Over the past few decades, there have been many aspects of uncertainty regarding GERD leading to an ongoing interest in the field as reflected by a large number of publications, whose heterogeneity and variable quality may present a challenge for researchers to measure their scientific impact, identify scientific collaborations, and to grasp actively researched themes in the GERD field. Accordingly, we aim to evaluate the knowledge structure, evolution of research themes, and emerging topics of GERD research between 2012 and 2022 with the help of bibliometric approaches.

Methods

The literature focusing on GERD from 2012 to 2022 was retrieved from the Science Citation Index Expanded of the Web of Science Core Collection. The overall publication performance, the most prolific countries or regions, authors, journals and resources-, knowledge- and intellectual-networking, as well as the co-citation analysis of references and keywords, were analyzed through Microsoft Office Excel 2019, CiteSpace, and VOSviewer.

Results

A total of 8,964 publications were included in the study. The USA published the most articles (3,204, 35.74%). Mayo Clin ranked first in the number of articles published (201, 2.24%). EDOARDO SAVARINO was the most productive author (86, 0.96%). The most productive journal in this field was SURGICAL ENDOSCOPY AND OTHER INTERVENTIONAL TECHNIQUES (304, 3.39%). AMERICAN JOURNAL OF GASTROENTEROLOGY had the most co-citations (4,953, 3.30%). Keywords with the ongoing strong citation bursts were transoral incision less fundoplication, eosinophilic esophagitis, baseline impedance, and functional heartburn.

Conclusion

For the first time, we obtained deep insights into GERD research through bibliometric analysis. Findings in this study will be helpful for scholars seeking to understand essential information in this field and identify research frontiers.

First Therapeutic Approval for Eosinophilic Esophagitis

Eosinophilic esophagitis (EE) is a chronic, immune-mediated or antigen-mediated esophageal disease. Treatment for patients with EE can be challenging with no previously approved medications. Current management strategies follow the four D’s paradigm of drugs, dietary elimination, dilation, and disease anxiety and hypervigilance therapy. On 20 May 2022, dupilumab was approved by FDA for EE. A dose of 300 mg dupilumab weekly significantly improved signs and symptoms of EE compared to placebo in a phase 3 trial. The approval of dupilumab will fulfill an unmet need for the increasing number of patients with EE.

Claudin-1 Mediated Tight Junction Dysfunction as a Contributor to Atopic March

Atopic march refers to the phenomenon wherein the occurrence of asthma and food allergy tends to increase after atopic dermatitis. The mechanism underlying the progression of allergic inflammation from the skin to gastrointestinal (GI) tract and airways has still remained elusive. Impaired skin barrier was proposed as a risk factor for allergic sensitization. Claudin-1 protein forms tight junctions and is highly expressed in the epithelium of the skin, airways, and GI tract, thus, the downregulation of claudin-1 expression level caused by CLDN-1 gene polymorphism can mediate common dysregulation of epithelial barrier function in these organs, potentially leading to allergic sensitization at various sites. Importantly, in patients with atopic dermatitis, asthma, and food allergy, claudin-1 expression level was significantly downregulated in the skin, bronchial and intestinal epithelium, respectively. Knockdown of claudin-1 expression level in mouse models of atopic dermatitis and allergic asthma exacerbated allergic inflammation, proving that downregulation of claudin-1 expression level contributes to the pathogenesis of allergic diseases. Therefore, we hypothesized that the tight junction dysfunction mediated by downregulation of claudin-1 expression level contributes to atopic march. Further validation with clinical data from patients with atopic march or mouse models of atopic march is needed. If this hypothesis can be fully confirmed, impaired claudin-1 expression level may be a risk factor and likely a diagnostic marker for atopic march. Claudin-1 may serve as a valuable target to slowdown or block the progression of atopic march.

IL-20 subfamily cytokines impair the oesophageal epithelial barrier by diminishing filaggrin in eosinophilic oesophagitis

OBJECTIVE

Disruption of the epithelial barrier plays an essential role in developing eosinophilic oesophagitis (EoE), a disease defined by type 2 helper T cell (Th2)-mediated food-associated and aeroallergen-associated chronic inflammation. Although an increased expression of interleukin (IL)-20 subfamily members, IL-19, IL-20 and IL-24, in Th2-mediated diseases has been reported, their function in EoE remains unknown.

DESIGN

Combining transcriptomic, proteomic and functional analyses, we studied the importance of the IL-20 subfamily for EoE using patient-derived oesophageal three-dimensional models and an EoE mouse model.

RESULTS

Patients with active EoE have increased expression of IL-20 subfamily cytokines in the oesophagus and serum. In patient-derived oesophageal organoids stimulated with IL-20 cytokines, RNA sequencing and mass spectrometry revealed a downregulation of genes and proteins forming the cornified envelope, including filaggrins. On the contrary, abrogation of IL-20 subfamily signalling in Il20R2 ^-/- animals resulted in attenuated experimental EoE reflected by reduced eosinophil infiltration, lower Th2 cytokine expression and preserved expression of filaggrins in the oesophagus. Mechanistically, these observations were mediated by the mitogen-activated protein kinase (MAPK); extracellular-signal regulated kinases (ERK)1/2) pathway. Its blockade prevented epithelial barrier impairment in patient-derived air-liquid interface cultures stimulated with IL-20 cytokines and attenuated experimental EoE in mice.

CONCLUSION

Our findings reveal a previously unknown regulatory role of the IL-20 subfamily for oesophageal barrier function in the context of EoE. We propose that aberrant IL-20 subfamily signalling disturbs the oesophageal epithelial barrier integrity and promotes EoE development. Our study suggests that specific targeting of the IL-20 subfamily signalling pathway may present a novel strategy for the treatment of EoE.

Shukri N, Wong KK, Mohd Ashari NS. Zonula occludens-1 expression is reduced in nasal epithelial cells of allergic rhinitis patients

Allergic rhinitis (AR) is a common allergic disease characterized by disruption of nasal epithelial barrier. In this study, we investigated the mRNA expression of zonula occludens-1 (ZO-1), ZO-2 and ZO-3 and histone deacetylase 1 (HDAC1) and HDAC2 in AR patients compared to healthy controls. RNA samples were extracted from nasal epithelial cells of house dust mites (HDMs)-sensitized AR patients and healthy controls (n = 28 in each group). The RNAs were reverse transcribed into cDNAs for measurement of ZO-1, ZO-2, ZO-3, HDAC1 and HDAC2 expression levels by quantitative PCR. The mRNA expression of ZO-1 was significantly decreased in AR patients compared to healthy controls (p = 0.010). No significant difference was observed in the expression levels of ZO-2, ZO-3, HDAC1 and HDAC2 in AR patients compared to healthy controls. We found significant associations of higher HDAC2 levels in AR patients with lower frequency of changing bedsheet (p = 0.043) and with AR patients sensitized to Dermatophagoides farinae (p = 0.041). Higher expression of ZO-2 was observed in AR patients who had pets (p = 0.007). In conclusion, our data indicated that ZO-1 expression was lower in AR patients contributing to decreased integrity of nasal epithelial barrier integrity, and HDAC2 may be involved in the pathogenesis of the disease.

Formulations of Topical Steroids in Eosinophilic Esophagitis-Current Treatment and Emerging Possibilities

Eosinophilic esophagitis (EoE) is a chronic immune-mediated disorder characterised by eosinophilic inflammation and esophageal dysfunction symptoms. The recommended first-line treatment options are proton pump inhibitors and swallowed topical steroids (STS). However, current recommendations regarding STS are based on relatively few studies employing various doses and formulations. Our aim was to review the STS formulations currently used in the treatment of eosinophilic esophagitis, to demonstrate in a practical way the variety of exiting application methods, and to present emerging options for STS delivery to the esophagus. After the literature review, we established that the three most commonly used STS formulations include mist from an inhaler, viscous suspensions compounded with vehicles for oral use, and a recently introduced proprietary medication in the form of orodispersible tablets. Several drug delivery technologies with potential use in EoE are under investigation. To ensure optimal adherence, the choice of formulation should be based on efficacy, patient preferences and experience of the clinician, as well as current recommendations. Further studies are needed to compare the efficacy and acceptability of existing STS types, and to develop new, well-tolerated and effective drug formulations.

Type 2 Inflammation in Eosinophilic Esophagitis: From Pathophysiology to Therapeutic Targets

Eosinophilic esophagitis (EoE) is a chronic immune-mediated disease of the esophagus characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation, whose incidence is rising. It significantly affects patients’ quality of life and, if left untreated, results in fibrotic complications. Although broad consensus has been achieved on first-line therapy, a subset of patients remains non-responder to standard therapy. The pathogenesis of EoE is multifactorial and results from the complex, still mostly undefined, interaction between genetics and intrinsic factors, environment, and antigenic stimuli. A deep understanding of the pathophysiology of this disease is pivotal for the development of new therapies. This review provides a comprehensive description of the pathophysiology of EoE, starting from major pathogenic mechanisms (genetics, type 2 inflammation, epithelial barrier dysfunction, gastroesophageal reflux, allergens, infections and microbiota) and subsequently focusing on the single protagonists of type 2 inflammation (involved cells, cytokines, soluble effectors, surface proteins and transcription factors) that could represent present and future therapeutic targets, while summarizing previous therapeutic approaches in literature.

Barrier Impairment and Type 2 Inflammation in Allergic Diseases: The Pediatric Perspective

Allergic diseases represent a global burden. Although the patho-physiological mechanisms are still poorly understood, epithelial barrier dysfunction and Th2 inflammatory response play a pivotal role. Barrier dysfunction, characterized by a loss of differentiation, reduced junctional integrity, and altered innate defence, underpins the pathogenesis of allergic diseases. Epithelial barrier impairment may be a potential therapeutic target for new treatment strategies Up now, monoclonal antibodies and new molecules targeting specific pathways of the immune response have been developed, and others are under investigation, both for adult and paediatric populations, which are affected by atopic dermatitis (AD), asthma, allergic rhinitis (AR), chronic rhinosinusitis with nasal polyps (CRSwNP), or eosinophilic esophagitis (EoE). In children affected by severe asthma biologics targeting IgE, IL-5 and against IL-4 and IL-13 receptors are already available, and they have also been applied in CRSwNP. In severe AD Dupilumab, a biologic which inhibits both IL-4 and IL-13, the most important cytokines involved in inflammation response, has been approved for treatment of patients over 12 years. While a biological approach has already shown great efficacy on the treatment of severe atopic conditions, early intervention to restore epithelial barrier integrity, and function may prevent the inflammatory response and the development of the atopic march.

Innate lymphoid cells: The missing part of a puzzle in food allergy

Food allergy is an increasingly prevalent disease driven by uncontrolled type 2 immune response. Currently, knowledge about the underlying mechanisms that initiate and promote the immune response to dietary allergens is limited. Patients with food allergy are commonly sensitized through the skin in their early life, later on developing allergy symptoms within the gastrointestinal tract. Food allergy results from a dysregulated type 2 response to food allergens, characterized by enhanced levels of IgE, IL-4, IL-5, and IL-13 with infiltration of mast cells, eosinophils, and basophils. Recent studies raised a possible role for the involvement of innate lymphoid cells (ILCs) in driving food allergy. Unlike lymphocytes, ILCs lack They represent a group of lymphocytes that lack specific antigen receptors. ILCs contribute to immune responses not only by releasing cytokines and other mediators but also by responding to cytokines produced by activated cells in their local microenvironment. Due to their localization at barrier surfaces of the airways, gut, and skin, ILCs form a link between the innate and adaptive immunity. This review summarizes recent evidence on how skin and gastrointestinal mucosal immune system contribute to both homeostasis and the development of food allergy, as well as the involvement of ILCs toward inflammatory processes and regulatory mechanisms.

Water Extract of Rubus coreanus Prevents Inflammatory Skin Diseases In Vitro Models

Atopic dermatitis (AD) is a chronic inflammatory skin disease caused by immune hypersensitivity reaction. The cause of AD is unclear, but its symptoms have a negative effect on quality of life; various treatment methods to alleviate these symptoms are underway. In the present study, we aimed to evaluate in vitro antioxidant and anti-inflammatory effects of Rubus coreanus water extract (RCW) on AD. Total phenolic compounds and flavonoid content of RCW were 4242.40 ± 54.84 mg GAE/g RCE and 1010.99 ± 14.75 mg CE/g RCW, respectively. RCW reduced intracellular reactive oxygen species level and increased the action of antioxidant enzymes, such as catalase, superoxide dismutase, and glutathione peroxidase in tumor necrosis factor-α (TNF-α)/interferon-γ (IFN-γ)-stimulated HaCaT cells. Moreover, mRNA expression of the pro-inflammatory cytokines, including TNF-α, interleukin-1β, and interleukin-6, was downregulated by RCW in the TNF-α/IFN-γ-stimulated cells. The levels of inflammatory chemokines (thymus- and activation-regulated chemokine; eotaxin; macrophage-derived chemokine; regulated on activation, normal T-cell expressed and secreted; and granulocyte-macrophage colony-stimulating factor) and intercellular adhesion molecule-1 were decreased in the TNF-α/IFN-γ-stimulated HaCaT cells after RCW treatment. Additionally, the mRNA expression levels of filaggrin and involucrin, proteins that form the skin, were increased by RCW. Furthermore, RCW inhibited the nuclear factor kappa-light-chain-enhancer of the activated B cells pathway in the TNF-α/IFN-γ-stimulated HaCaT cells. Collectively, the present investigation indicates that RCW is a potent substance that inhibits AD.

Treatment for eosinophilic esophagitis

PURPOSE OF REVIEW

To summarize current dietary and pharmacologic approaches in the treatment of eosinophilic esophagitis (EoE).

RECENT FINDINGS

Studies comparing dietary approaches in EoE treatment support empiric elimination diets as the preferred approach to dietary EoE treatment, with no data to support use of currently available allergy tests to guide specific food elimination diets. Swallowed topical corticosteroid therapy is the current standard of care in pharmacologic EoE treatment, with similar effectiveness of fluticasone and budesonide, but their discontinuation results in return of both EoE symptoms and disease. A number of nonsteroid-based therapies are currently under investigation for the treatment of EoE, which are focused on targeting disease at a cellular level.

SUMMARY

EoE can be treated with diet or medications. Empiric elimination is presently the preferred dietary approach. Swallowed steroids is the standard of care to treat EoE with medication; however, there are several promising drugs currently undergoing clinical trials.

Treatment of eosinophlic esophagitis with swallowed topical corticosteroids

Eosinophilic esophagitis (EoE) is an emerging chronic local immune-mediated disease of the esophagus. Beside proton pump inhibitors and food-restriction-diets swallowed topical corticosteroids (STC) can be offered as a first line therapy according to current guidelines. This review describes the background and practical management of STCs in EoE. So far, mainly asthma inhalers containing either budesonide or fluticasone have been administered to the esophagus by swallowing these medications “off label”. Recently esophagus-targeted formulations of topical steroids have been developed showing clinicopathological response rates up to 85% - an orodispersible tablet of budesonide has been approved as the first “in label” medication for EoE in Europe in June 2018. Whereas it was shown that disease remission induction of EoE by STCs is highly effective, there is still a lack of data regarding long-term and maintenance therapy. However, current studies on STC maintenance therapy add some movement into the game.

Zonula occludens and nasal epithelial barrier integrity in allergic rhinitis

Allergic rhinitis (AR) is a common disease affecting 400 million of the population worldwide. Nasal epithelial cells form a barrier against the invasion of environmental pathogens. These nasal epithelial cells are connected together by tight junction (TJ) proteins including zonula occludens-1 (ZO-1), ZO-2 and ZO-3. Impairment of ZO proteins are observed in AR patients whereby dysfunction of ZOs allows allergens to pass the nasal passage into the subepithelium causing AR development. In this review, we discuss ZO proteins and their impairment leading to AR, regulation of their expression by Th1 cytokines (i.e., IL-2, TNF-α and IFN-γ), Th2 cytokines (i.e., IL-4 and IL-13) and histone deacetylases (i.e., HDAC1 and HDAC2). These findings are pivotal for future development of targeted therapies by restoring ZO protein expression and improving nasal epithelial barrier integrity in AR patients.

A decreased abundance of clostridia characterizes the gut microbiota in eosinophilic esophagitis

Abnormalities in the gut microbiome are associated with suppressed Th2 response (Belizario et al., 2018 Mediators Inflamm. 2018:2037838) and predisposition to atopic disease such as asthma and eczema. We investigated if this applies to eosinophilic esophagitis (EoE). Stool bacterial DNA was extracted and followed by 16S rRNA amplification from 12 patients with eosinophilic esophagitis and 12 controls. Alpha‐ and beta‐diversity were analyzed. Only two patients had asthma or atopy and one patient was on budesonide. No patients were on PPIs. Patients with EoE had lower gut microbiota alpha diversity (species richness, P = 0.09; Shannon index, P = 0.01). The microbial composition was distinct as evidenced by significantly different beta diversity (P = 0.03) when compared to healthy controls. There were also significant differences in relative abundance at multiple taxonomic levels when comparing the two communities; at the phylum level, we observed a marked decrease in Firmicutes and increase in Bacteroidetes and at the order and family level there were significant decreases in Clostridia and Clostridiales in patients with EoE (q ≤ 0.1). We conclude that there are significant differences in microbial community structure, microbial richness, and evenness and a significant decrease in taxa within the Clostridia in patients with EoE. Our data suggest that Clostridia based interventions could be tested as adjuncts to current therapeutic strategies in EoE.

Impedance and Histologic Characteristics of the Sub-Laryngeal Esophagus Distinguish Eosinophilic Esophagitis From Other Esophageal Disorders

BACKGROUND & AIMS

The region of the esophagus 15-17 cm below the incisors, called the sub-upper esophageal sphincter (sub-UES), has not been characterized in adults with eosinophilic esophagitis (EoE) but appears different during endoscopy. We investigated how the sub-UES differs from the remaining esophagus in patients with EoE and aimed to determine whether these differences be used to distinguish patients with EoE from those with lichen planus.

METHODS

We performed a prospective study of 14 patients with EoE, 7 patients with lichen planus (based on presence of Civatte bodies, dysphagia, and/or narrow esophagus with thin esophageal mucosa without signs of EoE), and 20 patients undergoing upper endoscopy for upper gastrointestinal or with dysphagia but without features of EoE (controls) at a single medical center from 2015 through 2018. Biopsies from the distal, middle, and sub-UES regions of the esophagus were analyzed by histology, quantitative PCR, and immunohistochemistry. We measured mucosal impedance (MI) in all subjects at the sub-UES and 2 cm, 5 cm, and 10 cm from the gastro-esophageal junction.

RESULTS

Patients with EoE had significantly fewer eosinophils (median, 2 eosinophils/high-powered field [HPF]; range, 0-8 eosinophils/HPF) in sub-UES tissues compared with distal esophagus (median, 50 eosinophils/HPF; range, 22.5-60.8 eosinophils/HPF; P < .0001) or middle esophagus (median, 32 eosinophils/HPF; range, 19.3-60; P < .0001). Sub-UES tissues from patients with EoE had significantly less basal cell hyperplasia (P < .01), papillary elongation (P < .01), and dilated intercellular spaces (P < .01) than middle or and distal esophagus. MI in the sub-UES did not differ significantly between patients with EoE vs controls (P = .24), but was significantly lower in patients with lichen planus (median, 1344 ohms; range, 1046-1488) than patients with EoE (median, 2880 ohms; range, 2149-4858) (P < .001). mRNA and protein expression patterns did not differ significantly in the sub-UES of patients with EoE vs controls, except for expression of desmoglein-1, which was increased in sub-UES tissues from patients with EoE.

CONCLUSIONS

Sub-UES tissues from patients with EoE differ in numbers of eosinophils, histologic features, and MI compared to controls or patients with lichen planus. These features might help to distinguish these 2 diseases.

Inflammatory bowel disease and biomarkers of gut inflammation and permeability in a community with high exposure to perfluoroalkyl substances through drinking water

Perfluoroalkyl substances (PFAS) can act as surfactants and have been suggested to be capable of affecting gut mucosa integrity, a possible factor in the pathogenesis of inflammatory bowel disease (IBD). So far, only PFOA has been shown to have a positive association with ulcerative colitis. The present study aimed to investigate the association of PFAS and clinically diagnosed IBD in the Ronneby cohort, a population with high PFAS exposure (especially high PFOS and PFHxS) from Aqueous Film-Forming Foam through drinking water, using registry data. Additionally, to explore associations of PFAS with fecal zonulin and calprotectin, subclinical biomarkers of gut inflammation and permeability, in a sub-set of participants from Ronneby and Karlshamn (a nearby control municipality). The registry study included all people that ever resided in Ronneby municipality at least one year between 1980 and 2013. Yearly exposure to contaminated drinking water was assessed based on residential addresses and waterworks supply data, and the population classified by early, mid and late periods in ascending level of contamination. Diagnosed IBD cases were retrieved from the Swedish National Patient register and cause-of-death register. The Cox proportional hazards model was used to derive the hazard ratios (HRs) for diagnosed IBD. The biomarker study included 189 individuals who provided fecal samples. Serum PFAS were measured using LC-MS/MS. Fecal zonulin and calprotectin were measured using ELISA. Linear regression was used to assess the associations between measured PFAS and biomarker levels. In the registry study, no raised HRs for diagnosed IBD were found for cohort subjects with mid (1995-2004) or late period (2005-2013) exposure compared to never exposure. Early period exposure only (1985-1994) showed raised HRs for Crohn's disease (HR = 1.58, p = 0.048) and other non-specified IBD (HR = 1.38, p = 0.037). In the biomarker study, Karlshamn showed higher fecal calprotectin levels (median = 99.6 mg/kg in Karlshamn vs. 66.8 mg/kg in Ronneby, p = 0.04). A trend of decreased calprotectin with increased serum PFAS indicated higher PFAS was associated with lower degree of gut inflammation (p = 0.002). No association between serum PFAS and fecal zonulin was found. In conclusion, the present study found no consistent evidence to support PFAS exposure as a risk factor for IBD.

Eosinophilic Esophagitis in Children: Clinical Findings and Diagnostic Approach

Eosinophilic esophagitis (EoE) is an emerging chronic immune and antigen-mediated clinicopathologic disease. During the last 2 decades, the incidence of this condition in children has increased significantly, thanks to practitioners for creating the awareness and higher use of diagnostic endoscopy. We have analysed paediatric literature on EoE focusing on the epidemiology, pathophysiology, clinical findings and diagnostic approach. EoE is pathogenically related to a Th2 inflammation characterized by a mixed IgE and non-IgEmediated reaction to food and/or environmental agents. This leads to esophageal dysfunction and remodeling accompanied by subepithelial fibrosis. EoE can be presented with several range of gastrointestinal symptoms, including regurgitation, vomiting, feeding difficulties or feeding refusal in infants and toddlers, as well as heartburn, dysphagia and food bolus impaction in older children and adults. The diagnostic suspicion is based on the presence of chronic symptoms of esophgeal dysfunction and esophageal eosinophilia characterised histologically by a significant eosinophilic infiltration of the oesophageal mucosa (>15 eosinophils per high powered field). In this review, we will provide an update on clinical presentation and diagnostic approach to EoE in children. We emphasized on the relevant aspects of the new clinical condition termed "PPI responsive esophageal eosinophilia", as entities distinct from EoE and the role of PPI trial in the diagnostic workup, therefore we proposed a new diagnostic algorithm.

Toll-like receptor 2 stimulation augments esophageal barrier integrity

BACKGROUND

Germline-encoded innate immune pattern recognition receptors (PRR) are expressed at epithelial surfaces and modulate epithelial defenses. Evidence suggests that stimulation of the Toll-like receptor (TLR) family of PRR may regulate epithelial barrier integrity by upregulating tight junction (TJ) complex protein expression, but it is not known whether this mechanism is utilized in esophageal epithelial cells. TJ complex proteins maintain intact barrier function and are dysregulated in atopic disorders including eosinophilic esophagitis.

METHODS

Pattern recognition receptors expression was assessed in EoE and control primary esophageal epithelial cells, demonstrating robust expression of TLR2 and TLR3. The three-dimensional air-liquid interface culture (ALI) model was used to test whether TLR2 or TLR3 stimulation alters epithelial barrier function using an in vitro model of human epithelium. Transepithelial electrical resistance (TEER) and FITC-Dextran permeability were evaluated to assess membrane permeability. ALI cultures were evaluated by histology, immunohistochemistry, Western blotting, and chromatin immunoprecipitation (ChIP).

RESULTS

TLR3 stimulation did not change TEER in the ALI model. TLR2 stimulation increased TEER (1.28- to 1.31-fold) and decreased paracellular permeability to FITC-Dextran, and this effect was abolished by treatment with anti-TLR2 blocking antibody. TJ complex proteins claudin-1 and zonula occludens-1 were upregulated following TLR2 stimulation, and ChIP assay demonstrated altered histone 4 acetyl binding at the TJP1 enhancer and CLDN1 enhancer and promoter following zymosan treatment, implying the occurrence of durable chromatin changes.

CONCLUSIONS

Our findings implicate the TLR2 pathway as a potential regulator of esophageal epithelial barrier function and suggest that downstream chromatin modifications are associated with this effect.

Emerging therapies for eosinophilic esophagitis

Despite advances in the pathologic understanding of eosinophilic esophagitis (EoE), as of yet, no single agent has been approved by the US Food and Drug Administration to treat EoE. Off-label, EoE is currently treated by using the 3 Ds: drugs (particularly swallowed topical corticosteroids), dietary restriction, and endoscopic dilation. In the recent past, considerable progress in terms of EoE treatment has been made: (1) new EoE-specific steroid formulations optimizing mucosal deposition have been developed, which has culminated in recent approval of a budesonide effervescent tablet in Europe; (2) biologics used for other T_H2-mediated diseases, such as allergic asthma and atopic eczema, as well as purpose-developed biologics, have been studied in phase II trials in patients with EoE; and (3) novel dietary restriction strategies have evolved. Finally, further insights into the pathogenesis of EoE have revealed several novel disease mediators that might be targeted in the future. In the following article we will discuss recent advances in EoE treatment with regard to swallowed topical steroids, biological agents, dietary approaches, and novel molecular targets.

Diagnostic and Therapeutic Long-term Management of Eosinophilic Esophagitis- Current Concepts and Perspectives for Steroid Use

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the esophagus, which requires short- and long-term treatment. In addition, patients under long-term treatment for any chronic condition should have a structured follow-up. The mainstays in EoE treatment are drugs (such as swallowed topical corticosteroids [STC] and proton pump inhibitors), dietary exclusions, and endoscopic dilations. STC are the most widely used treatment and have proven efficacy in inducing clinical, endoscopic and histological remission in active EoE. However, data regarding maintaining disease remission and long-term management are limited. Ongoing disease activity and relapses despite STC treatment are frequently observed. This sheds light on the urgent need for adequate maintenance strategies, which have not been well defined. In terms of follow-up concepts, to date neither guidelines nor consensus recommendations have been published. To summarize the current knowledge on long-term diagnostic and therapeutic STC management of EoE, we conducted a literature search using PubMed and Embase applying the following key search items: Eosinophilic esophagitis, eosinophils, esophagus, swallowed topical corticosteroids, fluticasone, budesonide, long-term, treatment, therapy, and follow-up. In addition, we present empirically developed long-term management concepts applied at two large EoE centers, with a special focus on STC treatments. Finally, we highlight areas of future research and perspectives regarding the long-term management of EoE.

Mucosal impedance testing: A new diagnostic testing in gastroesophageal reflux disease

Current diagnostic testing for gastroesophageal reflux disease (GERD) include endoscopy, ambulatory pH and intraluminal impedance monitoring. However, they are suboptimal and do not measure chronicity of reflux. Recently, a mucosal impedance (MI) device has been developed to measure esophageal epithelial conductivity changes, a marker of chronic GERD. The aim of this review is to summarize the use of MI testing (MIT) for the evaluation and management of esophageal disease. MIT is a minimally invasive and simple through-the-scope procedure performed during endoscopy. It allows for a rapid derivation of MI values within seconds without an uncomfortable overnight pH- impedance catheter. The MI values can correlate with histological findings of epithelial barrier dysfunction, normalize with effective treatment, and show promise for differentiating GERD from non-GERD conditions such as eosinophilic esophagitis (EoE). In conclusion, endoscopic MIT measurement can differentiate esophageal disorders instantly during endoscopy. It may not only serve as an important tool in diagnosing of GERD but also help guide therapy in clinically difficult situations as a surrogate to predict the treatment response.

Signals from the various immune cells in promoting food allergy-induced eosinophilic esophagitis like disease

Eosinophilic esophagitis (EoE) is a recently recognized esophageal inflammatory disease with clinical manifestations arising from esophageal dysfunction. The etiology of EoE is currently being clarified and food allergy is evolving as the central cornerstone of EoE disease pathogenesis. Given the large number of eosinophils in the esophagus of people with EoE verified by data from murine models EoE is widely considered as the hallmark T-helper type 2 (Th2) disease of the esophagus. It is also known that some eosinophilic inflammation is controlled by other subsets of T cells such as Th9 or Th17 and control is also exerted by type 2 innate lymphoid cells acting together with basophils. In this paper we review results from molecular studies of mouse models in light of the results from the first clinical trials targeting key cytokines in humans and present in-depth molecular understanding of EoE.

Epithelial HIF-1α/claudin-1 axis regulates barrier dysfunction in eosinophilic esophagitis

Epithelial barrier dysfunction is a significant factor in many allergic diseases, including eosinophilic esophagitis (EoE). Infiltrating leukocytes and tissue adaptations increase metabolic demands and decrease oxygen availability at barrier surfaces. Understanding of how these processes impact barrier is limited, particularly in allergy. Here, we identified a regulatory axis whereby the oxygen-sensing transcription factor HIF-1α orchestrated epithelial barrier integrity, selectively controlling tight junction CLDN1 (claudin-1). Prolonged experimental hypoxia or HIF1A knockdown suppressed HIF-1α-dependent claudin-1 expression and epithelial barrier function, as documented in 3D organotypic epithelial cultures. L2-IL5OXA mice with EoE-relevant allergic inflammation displayed localized eosinophil oxygen metabolism, tissue hypoxia, and impaired claudin-1 barrier via repression of HIF-1α/claudin-1 signaling, which was restored by transgenic expression of esophageal epithelial-targeted stabilized HIF-1α. EoE patient biopsy analysis identified a repressed HIF-1α/claudin-1 axis, which was restored via pharmacologic HIF-1α stabilization ex vivo. Collectively, these studies reveal HIF-1α's critical role in maintaining barrier and highlight the HIF-1α/claudin-1 axis as a potential therapeutic target for EoE.

Development and Validation of a Mucosal Impedance Contour Analysis System to Distinguish Esophageal Disorders

BACKGROUND & AIMS

Diagnostic testing for chronic esophageal disorders relies on histopathology analysis of biopsies or uncomfortable transnasal catheters or wireless pH monitoring, which capture abnormal intraluminal refluxate. We therefore developed a balloon mucosal impedance (MI) catheter system that instantly detects changes in esophageal mucosal integrity during endoscopy over a long segment of the esophagus. We performed a prospective study to evaluate the ability of a balloon-incorporated MI catheter to detect and evaluate esophageal disorders, including gastroesophageal reflux disease (GERD) and eosinophilic esophagitis (EoE).

METHODS

We performed a prospective study of 69 patients undergoing esophagogastroduodenoscopy with or without wireless pH monitoring. Patients were classified as having GERD (erosive esophagitis or abnormal pH; n = 24), EoE (confirmed with pathology analysis of tissues from both distal and proximal esophagus; n = 21), or non-GERD (normal results from esophagogastroduodenoscopy and pH tests; n = 24). Receiver operating characteristic curves and area under the operating characteristic curve (AUC) were used to compare the accuracy of balloon MI in diagnosis. Probabilities of assignment to each group (GERD, non-GERD, or EoE) were estimated using multinomial logistic regression. Association between MI patterns and diagnoses were validated using data from patients seen at 3 separate institutions.

RESULTS

MI pattern along the esophageal axis differed significantly (P < .01) among patients with GERD, EoE, and non-GERD. Patients with non-GERD had higher MI values along all measured segments. The MI pattern for GERD was easily distinguished from that of EoE: in patients with GERD, MI values were low in the distal esophagus and normalized along the proximal esophagus, whereas in patients with EoE, measurements were low in all segments of the esophagus. Intercept and rate of rise of MI value (slope) as distance increased from the squamocolumnar junction identified patients with GERD with an AUC = 0.67, patients with EoE with an AUC = 0.84, and patients with non-GERD with an AUC = 0.83 in the development cohort. One patient had an adverse event (reported mild chest pain after the procedure) and was discharged from the hospital without further events.

CONCLUSIONS

We developed a balloon MI catheter system that instantly detects changes in esophageal mucosal integrity during endoscopy and found it to be safe and able to identify patients with GERD, EoE, or non-GERD. We validated our findings in a separate cohort for patients. ClinicalTrials.gov ID NCT03103789.

Epithelial Claudin Proteins and Their Role in Gastrointestinal Diseases

Our bodies are protected from the external environment by mucosal barriers that are lined by epithelial cells. The epithelium plays a critical role as a highly dynamic, selective semipermeable barrier that separates luminal contents and pathogens from the rest of the body and controlling the absorption of nutrients, fluid and solutes. A series of protein complexes including the adherens junction, desmosomes, and tight junctions function as the principal barrier in paracellular diffusion and regulators of intracellular solute, protein, and lipid transport. Tight junctions are composed of a series of proteins called occludins, junctional adhesion molecules, and claudins that reside primarily as the most apical intercellular junction. Here we will review one of these protein families, claudins, and their relevance to gastrointestinal and liver diseases.

Comparison of mucosal impedance measurements throughout the esophagus and mucosal eosinophil counts in endoscopic biopsy specimens in eosinophilic esophagitis

BACKGROUND AND AIMS

Assessing eosinophilic esophagitis (EoE) activity from limited esophageal mucosal biopsy samples has been questioned. Here our aim was to compare mucosal impedance (MI) throughout the esophagus and eosinophil counts in endoscopic biopsy samples in EoE.

METHODS

We compared 20-site MI using a balloon catheter in the esophagus and eosinophils per high-power field (eos/HPF) in esophageal mucosal biopsy samples. Data are summarized as median (interquartile range) comparing control subjects and EoE using Mann-Whitney rank sum test and between endoscopic reference score and MI (minimal and average) using rank Spearman correlation.

RESULTS

Ten adult control patients (ages 38-70) and 23 EoE patients (ages 21-80, 18 active) were studied. The mean (range) pan-esophageal MI in control subjects was significantly higher (6435 ohms [4546-7301]) compared with EoE patients (2004 ohms [1437-2546], P < .001). In control patients 172 of 180 (95.6%) individual impedance measurements (18 per patient) were normal when compared with 126 of 432 (29.2%) measurements in EoE. No EoE patient had uniformly normal MI. MI varied widely, with 19 of 23 patients having values above and below 2300 ohms (normal) regardless of EoE activity. Correlation of maximim eos/HPF with minimum and average MI per patient was r = -.243, P = .072 and r = -.358, P = .086, respectively. Of 5 patients with inactive EoE, 3 had >50% abnormal MI segments. Correlation coefficients of the endoscopic reference score with minimum and average MI were r = -.154, P = .47 and r = -.27, P = .20, respectively. The procedure was <5 minutes without adverse events.

CONCLUSIONS

MI is lower in the esophagus of EoE patients compared with control subjects with poor correlation between peak esophageal eosinophil counts, EoE activity, and MI. Segmental esophageal MI provides a unique marker of esophageal dysfunction in EoE. (Clinical trial registration number: NCT02995395.).

New Developments in the Diagnosis and Treatment of Eosinophilic Esophagitis

PURPOSE OF REVIEW

Eosinophilic esophagitis (EoE) is a chronic, allergen-driven, immune-mediated disease of the esophagus that progresses to esophageal fibrostenosis if left untreated. The aim of this review is to provide a concise update on recent clinically relevant advances in the development of diagnostic and therapeutic approaches for EoE.

RECENT FINDINGS

Current diagnostic and disease monitoring protocols for EoE rely on repetitive endoscopic evaluations and esophageal tissue acquisition for histopathologic analysis. Recent advancements in EoE diagnosis include endoscopic functional lumen imaging probe (FLIP), transnasal endoscopy (TNE), and the emergence of non-invasive diagnostic tools including cytosponge, esophageal string test, and mucosal impedance probe. Biomarkers for EoE have not yet proven their clinical utility. No Food and Drug Administration (FDA)-approved drugs currently exist for the treatment of EoE. Topical corticosteroid, proton-pump inhibitors (PPI), elimination diet, and dilation are the current treatment modalities for confirmed EoE. Promising results from clinical trials are emerging for biologic agents that target the interleukin (IL)-13 and the IL-4/IL-13 receptor, specifically, RPC4046 and dupilumab, respectively. New diagnostic algorithms, non-invasive diagnostic strategies, and treatment modalities for EoE are emerging. Patients with EoE continue to require a multimodal and multi-disciplinary management approach.

Molecular basis and cellular mechanisms of eosinophilic esophagitis for the clinical practice

Eosinophilic esophagitis (EoE) is a chronic, allergen-driven inflammatory esophageal disease characterized by predominantly eosinophilic inflammation leading to esophageal dysfunction. Recent efforts to understand EoE have increased our knowledge of the disease. Areas covered: Multiple cells, molecules, and genes interplay with early life environmental factors in the pathophysiology of EoE to converge in the esophageal epithelium at the center of disease pathogenesis. Epithelial cells constitute a mayor cytokine source for TSLP and Calpain-14; an impaired epithelial barrier function allowing penetration of food and microbiota-derived antigens is involved in triggering and maintaining inflammation. Eosinophil and mast cell-derived products, including TGFβ, together with IL-1β and TNFα, promote epithelial mesenchymal transition in EoE, contributing to tissue remodeling by synthetizing and depositing extracellular matrix in subepithelial layers. This article aims to provide a state-of-the-art update on the pathophysiology of EoE applied to clinical practice, and latest research and developments with potential interest to improve the diagnosis and treatment of patients with EoE are revised. Expert commentary: Preliminary approaches have provided promising results toward incorporating minimally invasive methods for patient diagnosis and monitoring in clinical practice. Early diagnosis and optimized therapies will allow for personalized medicine in EoE.

Obesity and GERD impair esophageal epithelial permeability through 2 distinct mechanisms

BACKGROUND

The mechanism by which obesity leads to damage independent of reflux is unclear. We aimed to determine the influence of obesity on mean nocturnal baseline impedance (MNBI), a functional measure of the epithelial barrier, in the presence and absence of acid reflux, using ambulatory pH impedance measurements.

METHODS

Twenty-four-hour pH impedance studies performed off medications in Caucasian men with a normal endoscopic examination were assessed for level of acid exposure and MNBI. Four patient groups were studied: Group 1, Not obese and normal acid exposure; Group 2, Obese and normal acid exposure; Group 3, Not obese and increased acid exposure; and Group 4, Obese with increased acid exposure.

RESULTS

One hundred patients were studied (25 in each group). Mean esophageal mucosal impedance (MI) was substantially lower in obese patients without reflux (Group 2) and non-obese patients with reflux (Group 3) compared to normal controls (non-obese, no reflux, Group 1). MI was progressively lower in the distal (vs the proximal) esophagus in GER patients, compared to those without GER. This difference persisted in the presence or absence of obesity. In contrast, in obese patients, the mean MI was significantly lower throughout the esophagus when compared to the non-obese patients and also persisted in the presence and absence of accompanying reflux. Obesity and reflux were both independently negatively correlated with MI.

CONCLUSION

Obesity is associated with abnormal esophageal MNBI. In contrast to gastro-esophageal reflux, this decrease is pan-esophageal. These data may support a systemic mechanism by which obesity alters the esophageal barrier function.

Filaggrin and tight junction proteins are crucial for IL-13-mediated esophageal barrier dysfunction

Eosinophilic esophagitis (EoE) is an allergy-mediated disease that is accompanied by IL-13 overexpression and an impaired esophageal barrier. Filaggrin (FLG) and tight junction (TJ) proteins are considered to contribute to epithelial barrier function. However, their functional involvement in EoE has not been elucidated. Here, we aimed to determine the IL-13-mediated barrier dysfunction and expression of TJ-related proteins in EoE and to characterize interactions among TJ-related proteins involved in the barrier function of the esophageal epithelium. Biopsy specimens from EoE patients were analyzed. Primary human esophageal epithelial cells (HEECs) were cultured using an air-liquid interface (ALI) system. The permeability of TJs was assayed by biotinylation. Transepithelial electrical resistance (TEER) was measured after stimulation with IL-13 and after siRNA silencing of FLG expression. FLG and TJ genes and proteins were assessed by quantitative RT-PCR, Western blot analysis, and immunofluorescent staining. The biotinylation reagent diffused through the paracellular spaces of whole stratified epithelial layers in EoE biopsy samples. The TEER decreased in ALI-cultured HEECs after IL-13 stimulation. Although the protein level of FLG decreased, that of the TJ proteins increased in the mucosa of EoE biopsy samples and in ALI-cultured HEECs after IL-13 stimulation. IL-13 altered the staining patterns of TJ proteins and the epithelial morphology. FLG siRNA transfection significantly decreased TEER. The IL-13-mediated reduced esophageal barrier is associated with the altered expression pattern but not with the levels of TJ-associated proteins. A deficiency of FLG altered the stratified epithelial barrier. NEW & NOTEWORTHY Esophageal permeability to small molecules was increased in patients with eosinophilic esophagitis (EoE) and could be induced by IL-13 in our unique air-liquid interface-cultured primary multilayer human esophageal epithelial cells in vitro. A deficiency of filaggrin disrupted the esophageal stratified epithelial barrier. The decreased esophageal barrier in EoE was associated with the altered staining pattern of tight junction proteins, although the levels of the proteins themselves do not appear to be changed.

Mucosal Impedance: a New Approach to Diagnosing Gastroesophageal Reflux Disease and Eosinophilic Esophagitis

PURPOSE OF REVIEW

In this review, we discuss current diagnostic testing modalities for both gastroesophageal reflux disease (GERD) and eosinophilic esophagitis (EoE) and then introduce mucosal impedance (MI), a novel technology that measures epithelial integrity in real time during endoscopy. We describe the advantages and disadvantages of MI as compared with traditional diagnostic testing.

RECENT FINDINGS

We review studies that demonstrate that GERD and EoE have distinct MI patterns, and that physicians can accurately diagnose and distinguish the two during endoscopy with minimal time added to the procedure. We also review studies showing that MI has the capability to assess treatment response in both GERD and EoE and that it can be used to diagnose GERD in patients with extraesophageal reflux symptoms. Mucosal impedance testing is a major advancement in the diagnosis of GERD and EoE. Future studies are planned to assess whether MI can be used as a treatment endpoint in EoE and whether it can be used to predict response to anti-reflux surgery.

Medical and dietary management of eosinophilic esophagitis

OBJECTIVE

Eosinophilic esophagitis (EoE) is a disease of chronic, allergen-driven, T-helper 2 (Th2) immune-mediated inflammation that progresses to fibrostenosis of the esophagus if left untreated. There are currently no Food and Drug Administration (FDA)-approved drugs for the treatment of EoE. This review focuses on the medical and dietary management of EoE.

DATA SOURCES

Manuscripts on EoE treatments were identified on PubMed.

STUDY SELECTIONS

Original research, randomized control trials, retrospective studies, meta-analyses, case series, and on occasions, case reports of high relevance, were selected and reviewed.

RESULTS

Current treatment strategies available to EoE patients center on monotherapy or combination therapy with dietary modification to exclude antigenic stimulation and topical corticosteroids to control Th2-mediated tissue inflammation and pathologic remodeling. Dilation as a rescue therapy for the narrowed, fibrostenotic, symptomatic esophagus can potentially be avoided with optimal medical and elimination diet therapies. The molecular mechanisms underlying EoE pathogenesis are being unraveled, from which targeted therapies can be developed and evaluated in preclinical and clinical studies. Current clinical research efforts focus on optimization of topical corticosteroid delivery, dosing, frequency, and duration of treatment, either alone or in combination with tailored elimination diet. Preliminary clinical trials with biologics targeting interleukin (IL)-5 and IL-13/IL-4 have been completed.

CONCLUSION

Topical corticosteroid, elimination diet, and dilation are the current treatment modalities for confirmed EoE. The use of proton-pump inhibitors (PPI) is being suggested as a potential regimen to treat EoE, based on evolving understanding of PPI-responsive esophageal eosinophilia (PPI-REE). The complexity of EoE treatment regimens and frequent follow-ups require a multimodal, multi-disciplinary management approach to optimize patient care.

Esophageal Mucosal Impedance Patterns Discriminate Patients With Eosinophilic Esophagitis From Patients With GERD

BACKGROUND & AIMS

It is a challenge to make a diagnosis of eosinophilic esophagitis (EoE) because its symptoms and histologic features overlap with those of gastroesophageal reflux disease (GERD). A minimally invasive device was recently developed to detect mucosal impedance (MI) that measures epithelial integrity during upper endoscopy. We aimed to quantify MI along the esophagus and identify patterns that differentiated patients with and without GERD from those with EoE, and determine whether MI values and patterns are sufficient to identify patients with EoE using histologic findings as a reference.

METHODS

We performed a retrospective analysis of 91 patients with upper gastrointestinal symptoms referred for diagnostic testing for GERD and EoE from 2012 through 2014 (discovery set). During the first endoscopy, MI measurements were obtained at 2, 5, and 10 cm from the squamocolumnar junction. GERD was confirmed by ambulatory pH tests, and histologic analyses of biopsies were used to confirm EoE. We then used statistical modeling to identify MI patterns along the esophagus (at 10 cm, 5 cm, and 2 cm) that associated with GERD vs EoE. We validated our findings in a prospective cohort of 49 patients undergoing elective upper endoscopy for dysphagia, from 2015 through 2016, testing the ability of MI patterns to identify patients with vs. without EoE.

RESULTS

We found patients with EoE to have a unique MI pattern, with low values along the esophageal axis. MI measurements at 5 cm could discern patients with normal vs abnormal mucosa with 83% sensitivity and 79% specificity, and patients with EoE vs GERD with 84% sensitivity and 70% specificity; these measurements differentiated the patient populations with the highest level of accuracy of any of the 6 measurements tested. In the validation study, a rater using the esophageal MI pattern identified patients with EoE with 100% sensitivity and 96% specificity.

CONCLUSION

We identified and validated a pattern of MI along the esophagus that can identify patients with EoE vs normal mucosa or GERD with high levels of sensitivity.

The Esophageal Epithelial Barrier in Health and Disease

Dysfunction in the esophageal epithelial barrier function is a major source for morbidity. To better understand the pathophysiologic pathways of the diseases associated with barrier dysfunction, including gastroesophageal reflux disease, eosinophilic esophagitis, Barrett's esophagus, and obesity, it is important to understand the esophageal epithelial embryologic development, microscopic anatomy with a special focus on the barrier structure and function, extraepithelial defense mechanisms, and how these change in the diseased state. In recent years, significant progress has been made in elucidating the esophageal barrier structure and function both in vitro and in vivo. This has enhanced the understanding of mechanisms of disease, and may also allow identification of therapeutic targets that can help in the management of these diseases. This review provides a detailed discussion regarding the esophageal epithelial barrier structure and function, the current and historical techniques used to study the barrier, and how it is affected by common esophageal diseases.

Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory disease of the esophagus that effects children and adults. Typical symptoms of EoE typically involve failure to thrive and vomiting in small children, and dysphagia and food impaction in adolescents and adults. However, throat clearing, choking, gagging, and hoarseness have also been observed and these issues often bring patients to first seek otolaryngology and pulmonary evaluation. Diagnosis is only made by esophogastroduodenoscopy with biopsy, so clinicians must have a low threshold for considering eosinophilic esophagitis even in the absence of frank gastrointestinal symptoms.

TGF-β1 alters esophageal epithelial barrier function by attenuation of claudin-7 in eosinophilic esophagitis

Barrier dysfunction has been implicated in the pathophysiology of eosinophilic esophagitis (EoE). Transforming growth factor-β1 (TGF-β1), a potent pleiotropic molecule, is increased in EoE; however, no study has evaluated its influence on esophageal epithelial barrier. We hypothesized that TGF-β1 regulates barrier dysfunction in EoE. We aimed to determine the role of TGF-β1 in the epithelial barrier in models of EoE. To examine the impact of TGF-β1 on esophageal barrier, immortalized human esophageal epithelial (EPC2-hTERT) cells were exposed to TGF-β1 during the three-dimensional air-liquid interface (3D-ALI) model in vitro. TGF-β1 exposure diminished EPC2-hTERT barrier function as measured by transepithelial electrical resistance (TEER) and 3 kDa Fluorescein isothiocyanate dextran paracellular flux (FITC Flux), and hematoxylin and eosin (H&E) assessment revealed prominent cellular separation. In analysis of epithelial barrier molecules, TGF-β1 led to the specific reduction in expression of the tight-junction molecule, claudin-7 (CLDN7), and this was prevented by TGF-β-receptor I inhibitor. Short hairpin ribonucleic acid (shRNA)-mediated CLDN7 knockdown diminished epithelial barrier function, whereas CLDN7 overexpression resulted in protection from TGF-β1-mediated barrier dysfunction. In pediatric EoE biopsies CLDN7 expression was decreased and altered localization was observed with immunofluorescence analysis, and the TGF-β1 downstream transcription factor, phosphorylated SMAD2/3 (pSMAD2/3), was increased. Our data suggest that TGF-β1 participates in esophageal epithelial barrier dysfunction through CLDN7 dysregulation.