Development and dysfunction of structural cells in eosinophilic esophagitis.

Eosinophilic esophagitis (EoE) is a disorder characterized by dysfunction and chronic local inflammation of the esophagus. The incidence and prevalence of EoE are increasing worldwide. The mechanisms responsible are poorly understood, and effective treatment options are limited. From the lumen outward, the esophagus comprises stratified squamous epithelium, lamina propria, and muscle. The tissue-specific nature of EoE strongly suggests that structural cells in the esophagus are involved in the EoE diathesis. Epithelial basal cell hyperplasia and dilated intercellular spaces are cardinal features of EoE. Some patients with EoE develop lamina propria fibrosis, strictures, or esophageal muscle dysmotility. Clinical symptoms of EoE are only weakly correlated with peak eosinophil count, implying that other cell types contribute to EoE pathogenesis. Epithelial, endothelial, muscle, and fibroblast cells can each initiate inflammation and repair, regulate tissue resident immune cells, recruit peripheral leukocytes, and tailor adaptive immune cell responses. A better understanding of how structural cells maintain tissue homeostasis, respond to cell-intrinsic and cell-extrinsic stressors, and exacerbate and/or resolve inflammatory responses in the esophagus is needed. This knowledge will facilitate the development of more efficacious treatment strategies for EoE that can restore homeostasis of both hematopoietic and structural elements in the esophagus.

Triggers for eosinophilic esophagitis (EoE): The intersection of food allergy and EoE.

Eosinophilic esophagitis and IgE-mediated food allergy are both food-triggered diseases that are increasing in prevalence. They share many clinical links, including significant comorbidity and similar food triggers, and as atopic diseases, they likely share upstream mechanisms related to barrier function and signals leading to TH2 skewing. In this review, we focus on links between eosinophilic esophagitis and IgE-mediated food allergy with an emphasis on what insights may be derived from overlapping food triggers and immune phenotypes. Through further investigation of these connections, we may be able to better understand not only IgE-mediated food allergy and eosinophilic esophagitis but also general atopic response to food proteins and evolution of allergic response to food.

Causality of Helicobacter pylori infection on eosinophilic esophagitis and potential pathogenesis: a Mendelian randomization study.

Background: Observational studies have indicated a possible connection between Helicobacter pylori (H. pylori) infection and eosinophilic esophagitis (EoE), but their causal relationship has yet to be established. To investigate the causal associations between H. pylori infection and EoE, we performed a Mendelian randomization (MR) analysis. Methods: Firstly, we conducted both univariable and multivariable Mendelian randomization (MR) analyses. Furthermore, a two-step MR was carried out to ascertain the potential underlying pathways of these associations, particularly the involvement of inflammatory cytokines. We employed the inverse-variance weighted (IVW) method as the main analysis in our MR study. To enhance the credibility of the results, we also conducted several sensitivity analyses. Results: Our study demonstrated a noteworthy correlation between genetically predicted anti-H. pylori IgG antibody levels and a reduced risk of EoE (OR=0.325, 95% CI=0.165-0.643, P value=0.004, adj p value=0.009). No significant causal associations were detected between other H. pylori antibodies and EoE in our study. When it comes to multivariable MR analysis controlling for education attainment, household income, and deprivation individually, the independent causal impact of anti-H. pylori IgG on EoE persisted. Surprisingly, the two-step MR analysis indicated that inflammatory factors (IL-4, IL-5, IL-13, IL-17, and IFN-γ) did not appear to mediate the protective effect of H. pylori infection against EoE. Conclusion: Findings suggested that among the range of H. pylori-related antibodies, anti-H. pylori IgG antibody is the sole causal factor associated with protection against EoE. Certain inflammatory factors may not be involved in mediating this association. These findings make a significant contribution to advancing our understanding of the pathogenesis of EoE and its evolving etiology.

Circulating immunome fingerprint in eosinophilic esophagitis is associated with clinical response to proton pump inhibitor treatment.

Objectives: The aim of the study was to characterize the circulating immunome of patients with EoE before and after proton pump inhibitor (PPI) treatment in order to identify potential non-invasive biomarkers of treatment response. Methods: PBMCs from 19 healthy controls and 24 EoE patients were studied using a 39-plex spectral cytometry panel. The plasmacytoid dendritic cell (pDC) population was differentially characterized by spectral cytometry analysis and immunofluorescence assays in esophageal biopsies from 7 healthy controls and 13 EoE patients. Results: Interestingly, EoE patients at baseline had lower levels of circulating pDC compared with controls. Before treatment, patients with EoE who responded to PPI therapy had higher levels of circulating pDC and classical monocytes, compared with non-responders. Moreover, following PPI therapy pDC levels were increased in all EoE patients, while normal levels were only restored in PPI-responding patients. Finally, circulating pDC levels inversely correlated with peak eosinophil count and pDC count in esophageal biopsies. The number of tissue pDCs significantly increased during active EoE, being even higher in non-responder patients when compared to responder patients pre-PPI. pDC levels decreased after PPI intake, being further restored almost to control levels in responder patients post-PPI. Conclusions: We hereby describe a unique immune fingerprint of EoE patients at diagnosis. Moreover, circulating pDC may be also used as a novel non-invasive biomarker to predict subsequent response to PPI treatment.

Diagnosis, management and therapeutic options for eosinophilic esophagitis.

PURPOSE OF REVIEW: Eosinophilic esophagitis is a chronic and commonly evolving condition leading to relevant and potentially irreversible burden in terms of tissue damage and related functional impairment, thus significantly impacting on quality of life. The aim of the present review is to summarize the recent advances in terms of diagnostic work-up and pharmacological and nonpharmacological management of the disease, under the broader perspective of type 2 inflammation. RECENT FINDINGS: Two major novelties have prompted an innovative approach to EoE. In terms of diagnosis, it has been proposed to dissect the disease heterogeneity in three endotypes, independent from tissue eosinophil number: EoEe1, characterized by normal appearing oesophagus; EoEe2, associated with type 2 inflammation and steroid-refractoriness; EoEe3, whose features include adult onset, a more fibro-stenotic aspect and loss of epithelial gene expression. Concerning treatment, two recently licensed drugs for EoE, oro-dispersible budesonide and dupilumab represent the first treatment options specifically developed for EoE and addressing EoE-related peculiar pathobiological features. SUMMARY: In the era of precision medicine, managing EoE according to a phenotype-driven approach might be helpful in defining the best treatment options in the different disease forms or stages. In addition, exploring the coexistence or the previous occurrence of other type 2 conditions may suggest the opportunity to specifically target type 2 inflammation through biologic therapy. The complex EoE pathobiology combining inflammatory and functional features, both at organ and systemic level, requires a multidimensional approach relying on the strict integration of gastroenterologists and allergist-immunologists.

Common and disparate clinical presentations and mechanisms in different eosinophilic gastrointestinal diseases.

Eosinophilic gastrointestinal diseases (EGIDs) are a group of diseases characterized by selective eosinophil infiltration of the gastrointestinal (GI) tract in the absence of other causes of eosinophilia. These diseases are generally driven by type 2 inflammation, often in response to food allergen exposure. Among all EGIDs, the clinical presentation often includes a history of atopic disease with a variety of GI symptoms. EGIDs are traditionally separated into eosinophilic esophagitis (EoE) and non-EoE EGIDs. EoE is relatively better understood and now associated with clinical guidelines and 2 US Food and Drug Administration-approved treatments, whereas non-EoE EGIDs are rarer and less well-understood diseases without US Food and Drug Administration-approved treatments. Non-EoE EGIDs are further subclassified by the area of the GI tract that is involved; they comprise eosinophilic gastritis, eosinophilic enteritis (including eosinophilic duodenitis), and eosinophilic colitis. As with other GI disorders, the disease presentations and mechanisms differ depending on the involved segment of the GI tract; however, the differences between EoE and non-EoE EGIDs extend beyond which GI tract segment is involved. The aim of this article is to summarize the commonalities and differences between the clinical presentations and disease mechanisms for EoE and non-EoE EGIDs.

Minimally Invasive Approaches to Diagnose and Monitor Eosinophilic GI Diseases.

PURPOSE OF REVIEW: This review seeks to understand novel avenues for eosinophilic GI disease management. Biomarkers offer a unique and non-invasive approach to tracking EoE disease progression. While no biomarkers have definitively met the diagnostic criteria for eosinophilic GI diseases, some biomarkers have been shown to be associated with disease activity. Here, we examine the potential of recently studied biomarkers. RECENT FINDINGS: Current research shows advancements in blood, luminal fluid, and breath testing. Particular areas of interest include mRNA analyses, protein fingerprinting, amplicon sequence variants (ASVs), T cells and IgE receptors, eosinophilic cationic proteins, cytokines, and nitric oxide exhalation. Preliminary results showed that mucosal biomarkers, directly captured from the esophagus, may reflect the best representation of biopsy-based results, in contrast to biomarkers obtained from indirect or peripheral (blood, breath) methods. However, this is based on limited clinical studies without sufficient numbers to evaluate true diagnostic accuracy. Large-scale randomized trials are needed to fully ascertain both the optimal sampling technique and the specific biomarkers that reflect diagnostic status of the disease.

Machine learning-based identification and characterization of mast cells in eosinophilic esophagitis.

BACKGROUND: Eosinophilic esophagitis (EoE) is diagnosed and monitored using esophageal eosinophil levels; however, EoE also exhibits a marked, understudied esophageal mastocytosis. OBJECTIVES: Using machine learning, we localized and characterized esophageal mast cells (MCs) to decipher their potential role in disease pathology. METHODS: Esophageal biopsy samples (EoE, control) were stained for MCs by anti-tryptase and imaged using immunofluorescence; high-resolution whole tissue images were digitally assembled. Machine learning software was trained to identify, enumerate, and characterize MCs, designated Mast Cell-Artificial Intelligence (MC-AI). RESULTS: MC-AI enumerated cell counts with high accuracy. During active EoE, epithelial MCs increased and lamina propria (LP) MCs decreased. In controls and EoE remission patients, papillae had the highest MC density and negatively correlated with epithelial MC density. MC density in the epithelium and papillae correlated with the degree of epithelial eosinophilic inflammation, basal zone hyperplasia, and LP fibrosis. MC-AI detected greater MC degranulation in the epithelium, papillae, and LP in patients with EoE compared with control individuals. MCs were localized further from the basement membrane in active EoE than EoE remission and control individuals but were closer than eosinophils to the basement membrane in active EoE. CONCLUSIONS: Using MC-AI, we identified a distinct population of homeostatic esophageal papillae MCs; during active EoE, this population decreases, undergoes degranulation, negatively correlates with epithelial MC levels, and significantly correlates with distinct histologic features. Overall, MC-AI provides a means to understand the potential involvement of MCs in EoE and other disorders.

Epithelial overexpression of IL-33 induces eosinophilic esophagitis dependent on IL-13.

BACKGROUND: Eosinophilic esophagitis (EoE) is an increasingly common inflammatory condition of the esophagus; however, the underlying immunologic mechanisms remain poorly understood. The epithelium-derived cytokine IL-33 is associated with type 2 immune responses and elevated in esophageal biopsy specimens from patients with EoE. OBJECTIVE: We hypothesized that overexpression of IL-33 by the esophageal epithelium would promote the immunopathology of EoE. METHODS: We evaluated the functional consequences of esophageal epithelial overexpression of a secreted and active form of IL-33 in a novel transgenic mouse, EoE33. EoE33 mice were analyzed for clinical and immunologic phenotypes. Esophageal contractility was assessed. Epithelial cytokine responses were analyzed in three-dimensional organoids. EoE33 phenotypes were further characterized in ST2-/-, eosinophil-deficient, and IL-13-/- mice. Finally, EoE33 mice were treated with dexamethasone. RESULTS: EoE33 mice displayed ST2-dependent, EoE-like pathology and failed to thrive. Esophageal tissue remodeling and inflammation included basal zone hyperplasia, eosinophilia, mast cells, and TH2 cells. Marked increases in levels of type 2 cytokines, including IL-13, and molecules associated with immune responses and tissue remodeling were observed. Esophageal organoids suggested reactive epithelial changes. Genetic deletion of IL-13 in EoE33 mice abrogated pathologic changes in vivo. EoE33 mice were responsive to steroids. CONCLUSIONS: IL-33 overexpression by the esophageal epithelium generated immunopathology and clinical phenotypes resembling human EoE. IL-33 may play a pivotal role in the etiology of EoE by activating the IL-13 pathway. EoE33 mice are a robust experimental platform for mechanistic investigation and translational discovery.

Outcomes of Serum Food-Specific Immunoglobulin G 4 to Guide Elimination Diet in Patients With Eosinophilic Esophagitis.

INTRODUCTION: Eosinophilic esophagitis (EoE) is associated with atopy; however, recent studies have identified an association with food-specific immunoglobulin G 4 (FS-IgG 4 ) rather than immunoglobulin E antibodies. This study aimed to evaluate the role of serum FS-IgG 4 in guiding an elimination diet and its outcomes. METHODS: Patients with and without EoE were enrolled in a prospective, controlled, single tertiary center trial. Serum FS-IgG 4 titers, esophageal eosinophil counts, and dysphagia symptom questionnaire scores were assessed, and participants with elevated FS-IgG 4 (ImmunoCAP, cutoff of 10 mgA/L) commenced 6-week targeted elimination diet. Repeat serum FS-IgG 4 and endoscopic and histologic examination were performed at 6-week follow-up. RESULTS: Twenty-two patients with active EoE and 13 controls were recruited. Serum FS-IgG 4 to milk, wheat, soy, eggs, and nuts was significantly higher in EoE ( P = 0.0002, P = 0.002, P = 0.003, P = 0.012, and P < 0.001, respectively). Elevated serum FS-IgG 4 to 1 or more food groups (median 2) was identified in 21/22 (95.4%) patients with EoE; 20/21 underwent 6-week dietary elimination. Median reductions in dysphagia symptom questionnaire score and EoE endoscopic reference score after elimination were 8 ( P = 0.0007) and 1 ( P = 0.002), respectively. Nine (45%) patients had histological remission (<15 eosinophils per high-power field). Fall in median esophageal eosinophil count was not statistically significant (50 vs 23; P = 0.068). Serum FS-IgG 4 did not decline by 6-week follow-up. DISCUSSION: Serum FS-IgG 4 to milk, wheat, soy, egg, and nuts was present at higher levels in EoE, with targeted elimination resulting in 45% histologic remission rate. Serum FS-IgG 4 has potential as a noninvasive biomarker in EoE. When successful, FS-IgG 4 -led elimination diet can negate need for medications and be viewed more favorably by patients because of its smaller endoscopic burden compared with empirical elimination diets.

Animal models of eosinophilic esophagitis, review and perspectives.

Eosinophilic oesophagitis (EoE) is an allergen/immune-mediated chronic esophageal disease characterized by esophageal mucosal eosinophilic infiltration and esophageal dysfunction. Although the disease was originally attributed to a delayed allergic reaction to allergens and a Th2-type immune response, the exact pathogenesis is complex, and the efficacy of existing treatments is unsatisfactory. Therefore, the study of the pathophysiological process of EOE has received increasing attention. Animal models have been used extensively to study the molecular mechanism of EOE pathogenesis and also provide a preclinical platform for human clinical intervention studies of novel therapeutic agents. To maximize the use of existing animal models of EOE, it is important to understand the advantages or limitations of each modeling approach. This paper systematically describes the selection of experimental animals, types of allergens, and methods of sensitization and excitation during the preparation of animal models of EoE. It also discusses the utility and shortcomings of each model with the aim of providing the latest perspectives on EoE models and leading to better choices of animal models.

Changes in mucosal IgG4+- and IL-10+-cell frequencies in adults with eosinophilic esophagitis on a two-food elimination diet.

Eosinophilic esophagitis (EoE) is increasingly diagnosed in patients with dysphagia. Type-2 immunity can induce EoE histopathology via non-IgE-dependent mechanisms, possibly involving IgG4 and IL-10. To elucidate the contribution of this response to EoE pathogenesis, we examined its association with clinical and histologic endpoints in adult EoE patients given a two-food elimination diet. IgG4- and IL-10-expressing cells were counted in esophageal biopsies and serum food-specific IgG4 measured at baseline and follow-up. Variables were correlated with histologic measures of disease activity. Patients exhibited significant reduction in esophageal eosinophilia and overall histology. A significant decrease in IL-10+-cell frequencies correlated with histologic changes. In contrast, a decline in serum and esophageal IgG4, while substantial, did not correlate with IL-10+-cell frequencies or histologic parameters. These results suggest a critical role of IL-10 in EoE pathogenesis. Conversely, IgG4 expression, while reflecting exposure to food antigens, is not obviously related to EoE histopathology or IL-10 expression.

Eosinophilic Esophagitis due to Aeroallergens: A Systematic Review and Update

Eosinophilic esophagitis is a chronic antigen-mediated esophageal disease characterized clinically by symptoms related to esophageal dysfunction and histologically by TH2 inflammation (at least 15 eosinophils/high power field) when other secondary systemic and local causes of esophageal eosinophilia are excluded. Although this disease was initially ascribed to a delayed reaction to food allergens, emerging evidence suggests that aeroallergens may also play a role in pathogenesis and disease course. Some studies support seasonal variations in the diagnosis of eosinophilic esophagitis and disease exacerbations owing to the increase in aeroallergens to which patients are sensitized. It is also known that this disease can be caused by extensive, identifiable exposure to aeroallergens and after treatment with specific immunotherapy based on food or aeroallergens. It was recently postulated that treatment of allergic rhinoconjunctivitis can improve the symptoms of eosinophilic esophagitis, although data are limited to case reports and small series. Currently, biomarkers and biologic therapies are not helpful for diagnosis or inducing clinical and histological remission of the disease. Nevertheless, there are high hopes for dupilumab. This review aims to give visibility to the involvement of aeroallergens in the triggering and exacerbation of eosinophilic esophagitis, since many of them, in addition to being airborne and inhalant, can also be ingested as food. Clearly, we must try to identify the cause of the disease to ensure remission. (AU)

Molecular Mechanisms of Eosinophilic Esophagitis.

Food hypersensitivity is a group of diseases arising from a specific immune response that reproduces on exposure to a given food. The current understanding of molecular mechanisms and immunopathology of non-IgE-mediated/mixed food hypersensitivity, e.g., eosinophilic esophagitis, contains many gaps in knowledge. This review aims to provide a modern classification and identify the primary diseases of non-IgE-mediated/mixed food hypersensitivity reactions, delineate the distinctive molecular features, and discuss recent findings in the immunopathology of eosinophilic esophagitis that may become a basis to develop valid biomarkers and novel therapies for this disease. Eosinophilic esophagitis is a recently recognized allergic-mediated disease with eosinophil-predominant esophagus inflammation. Its pathogenesis is a complicated network of interactions and signaling between epithelial, mesenchymal, and immune cells on molecular and intercellular levels. Alterations produced by overactivation of some cytokine signaling pathways, e.g., IL-13 or thymic stromal lymphopoietin (TSLP), were evolved and observed in this review from the viewpoints of molecular, genetic, epigenetic, and transcriptomic changes. Despite substantial experimental data, the reliable and representative mechanism of eosinophilic esophagitis pathogenesis has yet to show itself. So, the place of esophagitis between mixed and non-IgE-mediated allergic disorders and between eosinophilic gastrointestinal disorders currently seems vague and unclear.

Correlation of clinical symptoms, endoscopic features and density of oesophageal eosinophilia in children with newly-diagnosed eosinophilic esophagitis.

INTRODUCTION AND OBJECTIVE: Eosinophilic esophagitis (EoE) is an inflammatory immune-mediated oesophageal disease of growing prevalence. The aim of this study is to characterise the clinical symptoms, endoscopic features and histological findings, as well as their possible correlations, in newly-diagnosed EoE paediatric patients. MATERIAL AND METHODS: Between 2009-2018, the clinical records of patients diagnosed with EoE at the Paediatric Hospital in Warsaw, Poland, were retrospectively reviewed. Inclusion criteria were upper gastrointestinal tract symptoms in association with oesophageal mucosal biopsy specimens containing not less than 15 intraepithelial eosinophils per hpf. The prevalence and the possible correlations between symptoms, endoscopic features and the density of eosinophilic infiltration were analysed; the medical history of the comorbidities were also assessed. RESULTS: The study included 47 children (median age 9.5 years). The most common clinical symptoms were abdominal pain (53%) and GERD-like symptoms (26%). The most common macroscopic changes were white plaques and exudates in 47% and furrows in 34%. A macroscopically normal oesophagus was observed in 28% of the children. The median number of eosinophils was estimated to be 45 eosinophils/hpf (IQR: 30-60), and no significant differences were found between the density of eosinophil infiltration and clinical symptoms or endoscopic features. Moreover, 70% of the children had a history of an allergy disease, older children (>3 years) tended to have pollen allergy more often than younger children (p<0.05). CONCLUSIONS: The density of oesophageal eosinophilia does not correlate with symptoms or endoscopic findings in children with newl-diagnosed EoE.

Clonally expanded, GPR15-expressing pathogenic effector TH2 cells are associated with eosinophilic esophagitis.

Eosinophilic esophagitis (EoE) is an allergic disorder characterized by the recruitment of eosinophils to the esophagus, resulting in chronic inflammation. We sought to understand the cellular populations present in tissue biopsies of patients with EoE and to determine how these populations are altered between active disease and remission. To this end, we analyzed cells obtained from esophageal biopsies, duodenal biopsies, and peripheral blood of patients with EoE diagnosed with active disease or remission with single-cell RNA and T cell receptor (TCR) sequencing. Pathogenic effector TH2 (peTH2) cells present in the esophageal biopsies of patients with active disease expressed distinct gene signatures associated with the synthesis of eicosanoids. The esophageal tissue-resident peTH2 population also exhibited clonal expansion, suggesting antigen-specific activation. Peripheral CRTH2+CD161- and CRTH2+CD161+ memory CD4+ T cells were enriched for either a conventional TH2 phenotype or a peTH2 phenotype, respectively. These cells also exhibited substantial clonal expansion and convergence of TCR sequences, suggesting that they are expanded in response to a defined set of antigens. The esophagus-homing receptor GPR15 was up-regulated by peripheral peTH2 clonotypes that were also detected in the esophagus. Finally, GPR15+ peTH2 cells were enriched among milk-reactive CD4+ T cells in patients with milk-triggered disease, suggesting that these cells are an expanded, food antigen-specific population with enhanced esophagus homing potential.

Emerging Evidence for Pleiotropism of Eosinophils.

Eosinophils are complex granulocytes with the capacity to react upon diverse stimuli due to their numerous and variable surface receptors, which allows them to respond in very different manners. Traditionally believed to be only part of parasitic and allergic/asthmatic immune responses, as scientific studies arise, the paradigm about these cells is continuously changing, adding layers of complexity to their roles in homeostasis and disease. Developing principally in the bone marrow by the action of IL-5 and granulocyte macrophage colony-stimulating factor GM-CSF, eosinophils migrate from the blood to very different organs, performing multiple functions in tissue homeostasis as in the gastrointestinal tract, thymus, uterus, mammary glands, liver, and skeletal muscle. In organs such as the lungs and gastrointestinal tract, eosinophils are able to act as immune regulatory cells and also to perform direct actions against parasites, and bacteria, where novel mechanisms of immune defense as extracellular DNA traps are key factors. Besides, eosinophils, are of importance in an effective response against viral pathogens by their nuclease enzymatic activity and have been lately described as involved in severe acute respiratory syndrome coronavirus SARS-CoV-2 immunity. The pleiotropic role of eosinophils is sustained because eosinophils can be also detrimental to human physiology, for example, in diseases like allergies, asthma, and eosinophilic esophagitis, where exosomes can be significant pathophysiologic units. These eosinophilic pathologies, require specific treatments by eosinophils control, such as new monoclonal antibodies like mepolizumab, reslizumab, and benralizumab. In this review, we describe the roles of eosinophils as effectors and regulatory cells and their involvement in pathological disorders and treatment.