Eosinophilic esophagitis in adults is associated with IgG4 and not mediated by IgE

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.

A Conceptual Approach to Understanding Treatment Response in Eosinophilic Esophagitis

While the diagnosis and initial treatment of eosinophilic esophagitis are becoming more standardized, there are still major gaps in knowledge related to measuring treatment response. One such question centers on how to measure treatment response and what treatment endpoints should be. This impacts not only patient care and engagement in decision-making, but also the field of drug development. In addition, studies so far have use a myriad of treatment endpoints including over a dozen histologic endpoint criteria. This review will discuss the various stakeholders involved in assessment of treatment endpoints of a complex condition, including patients, practitioners and regulatory agencies, and the care settings in which treatment response is assessed, including routine clinical care, clinical trials, and observational studies. Potential parameters or treatment endpoints such as histology, symptoms, patient-reported outcomes, endoscopy, and biomarkers are discussed along with associated challenges and opportunities. A framework on how to define treatment outcomes is discussed and a conceptual approach treatment response is proposed. This takes into account histology, symptoms, and endoscopic findings and harnesses existing, validated tools. It includes definitions of nonresponse, complete normalization, and a graded response category between these 2 extremes, and also permits flexibility and latitude for modifications as newer knowledge emerges. In addition, ways to position the pediatric population in these endeavors are discussed as are future research directions.

Eosinophilic esophagitis: Current concepts in diagnosis and treatment

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

Eosinophilic esophagitis: early diagnosis is the key

Eosinophilic esophagitis (EoE) is a disorder which affects all ages, from infancy through adulthood. It typically affects atopic individuals (Table 1) and is a chronic allergic disorder, with foods ubiquitous in the diet being the most described trigger of this isolated eosinophilic inflammation of the esophagus in both adults and children. This inflammatory process leads to esophageal symptoms such as dysphagia and feeding intolerance. In this review, we provide a brief overview of the current state of EoE therapy and symptomatology and then try to make the case for early diagnosis and treatment to prevent some of the long-term consequences of esophageal inflammation.

Eosinophilic esophagitis in children: doubts and future perspectives

Background

Eosinophilic esophagitis (EoE) is a chronic immune-mediated inflammatory disorder and represents the leading cause of food impaction. The pathogenesis of EoE is the result of an interplay between genetic, environmental and host immune system factors. New therapeutic approaches for EoE have been proposed. In this manuscript we review the current evidence regarding EoE management in pediatric age, with a particular focus on new findings related to the efficacy and safety of monoclonal antibodies.

Main body

Conventional therapies have failed in treating some patients with EoE, which then requires aggressive procedures such as esophageal dilatation. The most effective available medical therapy for EoE is swallowed topic corticosteroids (fluticasone propionate and budesonide), which have two main drawbacks: they are related to well-known adverse effects (especially in the paediatric population), and there are not enough long-term data to confirm that they are able to reverse the remodelling process of the esophageal mucosa, which is the major cause of EoE symptoms (including dysphagia, abdominal pain, nausea, obstruction, perforation and vomiting). The monoclonal antibodies appear to be an interesting therapeutic approach. However, the studies conducted until now have shown substantial histological improvement not coupled with significant clinical improvements and no significant relationship between a decreasing number of eosinophils and clinical symptoms, highlighting the importance in the pathogenesis of EoE of cells such as T-helper cells, mast cells, B cells, epithelial cells and natural killer cells.

Conclusions

Monoclonal antibodies targeting a signal involved in the pathogenesis of EoE may not break the complex self-propagating inflammatory activation responsible for perpetuation of the inflammatory response and the development of symptoms and complications. We speculate that combined biological therapies targeting more than one molecule or cell may provide better results, with conventional therapies potentially enhancing the effects of antibodies. However, further studies should aim to find the best therapeutic approach to target the cells involved in the remodelling process and to reverse the histological changes in this complex clinical condition.

Allergic Comorbidity in Eosinophilic Esophagitis: Mechanistic Relevance and Clinical Implications

Allergic eosinophilic esophagitis (EoE) is a chronic, allergen-mediated inflammatory disease of the esophagus, and the most common cause of prolonged dysphagia in children and young adults in the developed world. While initially undistinguished from gastroesophageal reflux disease-associated esophageal eosinophilia, EoE is now recognized as a clinically distinct entity that shares fundamental inflammatory features of other allergic conditions and is similarly increasing in incidence and prevalence. The clinical and epidemiologic associations between EoE and other allergic manifestations are well established. In addition to exaggerated rates of atopic dermatitis, IgE-mediated food allergy, asthma, and allergic rhinitis in EoE patients, each of these allergic manifestations imparts individual and cumulative risk for subsequent EoE diagnosis. As such, EoE may be a member of the "allergic march"-the natural history of allergic manifestations during childhood. Several determinants likely contribute to the relationship between these conditions, including shared genetic, environmental, and immunologic factors. Herein, we present a comprehensive review of allergic comorbidity in EoE. We discuss areas of the genome associated with both EoE and other allergic diseases, including the well-studied variants encoding thymic stromal lymphopoietin and calpain 14, among other "atopic" regions. We summarize ways that environmental factors (such as microbiome-altering pressures and aeroallergen exposure) may predispose to multiple allergic conditions including EoE. Finally, we touch on some fundamental features of type 2 inflammation, and the resulting implications for the development of multiple allergic manifestations. We conclude with an analysis of the "type 2" biologics, and how mechanistic similarities between EoE and the other allergic manifestations have important implications for screening and treatment of the allergic patient.

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.

Cow's Milk Allergy: Immunomodulation by Dietary Intervention

Cow’s milk proteins cause allergic symptoms in 2% to 3% of all infants. In these individuals, the physiological mechanism of tolerance is broken with subsequent possible sensitization to antigens, which can lead eventually to allergic responses. The present review aims to provide an overview of different aspects of immune modulation by dietary intervention in cow’s milk allergy (CMA). It focuses on pathogenetic mechanisms of different CMA related disorders, e.g., gastroesophageal reflux and eosinophilic esophagitis, highlighting the role of dietary management on innate and adaptive immune systems. The traditional dietary management of CMA has greatly changed in the last years, moving from a passive approach, consisting of an elimination diet to relieve symptoms, to a “proactive” one, meaning the possibility to actively modulate the immune system. Thus, new insights into the role of hydrolysates and baked milk in immunomodulation are addressed here. Additionally, nutritional components, such as pre- and probiotics, may target the immune system via microbiota, offering a possible road map for new CMA prevention and treatment strategies.

Illuminating Elimination Diets: Controversies Regarding Dietary Treatment of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is an immune-mediated disease triggered by food antigens for which dietary elimination treatment can induce and sustain histologic remission. Our review aims to describe the state of the art regarding dietary treatment of EoE, highlighting a number of areas of controversy related to dietary therapy in EoE, including novel modalities for determining food triggers, making the empiric dietary elimination process more efficient, issues of cross-contamination and "dosing" of how much food to avoid or add back, costs and effects on quality of life, long-term efficacy, and the risk of developing immediate IgE-type reactions after initial dietary elimination. Elemental formulas, empiric elimination diets, and targeted allergy test-directed elimination diets are well-described treatments for EoE. Although elemental diets are most efficacious, their clinical use is limited by cost and the palatability of an exclusively liquid diet. While empiric elimination is less effective than elemental formula-based diets, they are more easily implemented and often sustainable. Since the comparative effectiveness of elimination diets with proton-pump inhibitors and swallowed topical steroids remains unknown, there are multiple areas to address with future research.

Blind Analysis of Food-Related IgG Identifies Five Possible Nutritional Clusters for the Italian Population: Future Implications for Pregnancy and Lactation

Background: The influence of diet in pregnant women on the immune tolerance process is intricate. Food-specific immunoglobulin G (IgG) was associated with exposure to particular food antigens. The IgG antibodies can cross the placental barrier and enter into the colostrum, and maternal IgG is amply present in breast milk. This justifies studying the immunological connection between food-specific IgG antibodies and the mother–fetus relationship. This study was designed to analyze food-specific IgG concentrations and possible food-specific IgG concentration clusters in a large cohort of subjects with a common food culture. Methods: Food-specific IgG antibody concentrations were detected in 18,012 Caucasian or Southern European subjects over 18 years of age. We used an unsupervised hierarchical clustering algorithm to explore varying degrees of similarity among food-specific IgG antibodies. Results: We identified five food groups by the evaluation of food-specific IgG values: one includes foods with a high nickel content, the second cluster is associated with gluten, the third cluster includes dairy products, the fourth one is connected to fermented foods, and the last group is correlated with cooked oils. Discussion: The knowledge derived from studying a large sample allows us to determine food-specific IgG values from a single pregnant woman, compare it to an epidemic standard, and establish modifications required in her lifestyle to modulate her nutritional habits.

Esophageal IgG4: Clinical, Endoscopic, and Histologic Correlations in Eosinophilic Esophagitis

OBJECTIVE

Recent studies show increased serum and esophageal IgG4 in patients with eosinophilic esophagitis (EoE), suggesting a possible IgG4-involved process. The role of IgG4 in pediatric EoE has not been extensively investigated. Our aim was to analyze IgG4 in esophageal tissue in children in parallel to that in adults with EoE.

METHODS

In a retrospective institutional review board-approved study, we performed immunohistochemical staining of IgG4 in esophageal biopsy specimens from 39 subjects: children with EoE (n = 16), adults with EoE (n = 15), children with reflux esophagitis (n = 4), and pediatric controls (n = 4). We assessed the relationships between IgG4 staining and clinical, endoscopic, and histopathologic characteristics.

RESULTS

Patients with EoE were significantly more likely to stain positively for IgG4 than children with reflux esophagitis or controls (P = 0.015). Fifteen of 31 (48%) EoE cases stained positively for IgG4. None of the reflux esophagitis or control cases stained positively. IgG4 staining had 48% sensitivity and 100% specificity for EoE. There was a trend toward IgG4 staining being associated with foreign body/food impaction (P = 0.153). There was a strong association between distal IgG4 staining and basal zone hyperplasia (P = 0.003).

CONCLUSIONS

Our study suggests IgG4 is not a consistent finding of EoE at disease diagnosis. Although IgG4 staining was specific for EoE, it had a poor sensitivity with positive staining in only 48% of EoE patients. Further studies are warranted to fully elucidate the role of IgG4 in EoE.

Correction to: Eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an atopic condition of the esophagus that has become increasingly recognized over the last 15 years. Diagnosis of the disorder is dependent on the patient’s clinical manifestations, and must be confirmed by histologic findings on esophageal mucosal biopsies. Patients with EoE should be referred to an allergist for optimal management, which may include dietary modifications and pharmacologic agents such as proton pump inhibitors (PPI) and corticosteroids, and for the diagnosis and management of comorbid atopic conditions. Mechanical dilation of the esophagus may also be necessary. The epidemiology, pathophysiology, diagnosis, treatment, and prognosis of EoE are discussed in this review.

Mechanisms of gastrointestinal allergic disorders

Gastrointestinal (GI) allergic disease is an umbrella term used to describe a variety of adverse, food antigen-driven, immune-mediated diseases. Although these diseases vary mechanistically, common elements include a breakdown of immunologic tolerance, a biased type 2 immune response, and an impaired mucosal barrier. These pathways are influenced by diverse factors such as diet, infections, exposure to antibiotics and chemicals, GI microbiome composition, and genetic and epigenetic elements. Early childhood has emerged as a critical period when these factors have a dramatic impact on shaping the immune system and therefore triggering or protecting against the onset of GI allergic diseases. In this Review, we will discuss the latest findings on the molecular and cellular mechanisms that govern GI allergic diseases and how these findings have set the stage for emerging preventative and treatment strategies.

IgG4-related disease: what a hematologist needs to know

IgG4-related disease is a fibro-inflammatory condition that can affect nearly any organ system. Common presentations include major salivary and lacrimal gland enlargement, orbital disease, autoimmune pancreatitis, retroperitoneal fibrosis and tubulointerstitial nephritis. This review focuses on the hematologic manifestations of IgG4-related disease, including lymphadenopathy, eosinophilia, and polyclonal hypergammaglobulinemia. The disease can easily be missed by unsuspecting hematologists, as patients may present with clinical problems that mimic disorders such as multicentric Castleman disease, lymphoma, plasma cell neoplasms and hypereosinophilic syndromes. When IgG4-related disease is suspected, serum protein electrophoresis and IgG subclasses are helpful as initial tests but a firm histological diagnosis is essential both to confirm the diagnosis and to rule out mimickers. The central histopathological features are a dense, polyclonal, lymphoplasmacytic infiltrate enriched with IgG4-positive plasma cells (with an IgG4/IgG ratio >40%), storiform fibrosis, and obliterative phlebitis. Importantly for hematologists, the latter two features are seen in all tissues except bone marrow and lymph nodes, making these two sites suboptimal for histological confirmation. Many patients follow an indolent course and respond well to treatment, but a significant proportion may have highly morbid or fatal complications such as periaortitis, severe retroperitoneal fibrosis or pachymeningitis. Corticosteroids are effective but cause new or worsening diabetes in about 40% of patients. Initial response rates to rituximab are high but durable remissions are rare. More intensive lymphoma chemotherapy regimens may be required in rare cases of severe, refractory disease, and targeted therapy against plasmablasts, IgE and other disease biomarkers warrant further exploration.

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.

Assessing the Risk Factors for Refractory Eosinophilic Esophagitis in Children and Adults

Background

Up to one-third of the patients suffering from eosinophilic esophagitis (EoE) present a refractory form, as defined by nonresponsiveness in clinical, endoscopic, or histological assessment after first-line therapy. Several studies recently investigated which factors can influence the development of this disease, but very few analyzed the factors underlying refractory EoE.

Methods

Medical charts of patients affected by EoE were retrospectively evaluated. Phenotyping of patients was conducted according to demographic, clinical, histological, and treatment variables. Then, patients were divided into responder and nonresponder to therapy and distinguished among children and adults.

Results

Forty-five children and 35 adult EoE patients were included. In the pediatric population, female sex (p < 0.05) and a higher score of visual analogue scale (VAS) at the follow-up visit (p = 0.02) were significantly associated to the risk of refractory EoE. Among adults, statistical significance was reached for years of follow-up (p = 0.001), diagnostic delay (p = 0.03), use of antibiotics during infancy (p = 0.01), and food allergy (p = 0.04).

Conclusions

Our study highlighted female sex and a higher VAS score at the time of follow-up visits as risk factors for refractory EoE in children, while the risk factors in adults were identified as fewer years of follow-up, greater diagnostic delay, use of antibiotics during infancy, and food allergy.

Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic disorder characterized by symptoms of esophageal dysfunction and esophageal inflammation with intraepithelial eosinophils. EoE represents an important cause of upper gastrointestinal morbidity. Primary care providers are pivotal for timely and accurate recognition of symptoms of eosinophilic esophagitis, for facilitating diagnoses through specialist referrals, and for understanding management strategies. This process begins with a thorough understanding of the clinical features of EoE, its associated atopic conditions, and its evolving epidemiology.

Pathophysiology of eosinophilic esophagitis: recent advances and their clinical implications

Introduction: Diagnostic and therapeutic strategies in eosinophilic esophagitis (EoE) are evolving. New knowledge regarding the pathophysiology of EoE has been the foundation for updated diagnostic recommendations and new therapeutic trials. Areas covered: We performed structured literature searches in Medline and PubMed, Cochrane meta-analyses, and abstracts of international congresses to review therapeutic approaches for EoE in July 2018. Additional articles were obtained by perusing the references of articles identified in the original PubMed search. Articles were excluded if they did not focus on the mechanism of disease, diagnosis, or treatment of humans with EoE. Expert commentary: Recent advances in the understanding of mechanisms underlying the pathology of EoE have resulted in significant change in the diagnostic algorithm for EoE, and are identifying promising potential targets for personalized medicine. There is a clinical need for improved targeted therapy for EoE, and better understanding the underlying pathophysiology of EoE will help to determine therapeutic targets. In this review, we highlight key mechanisms in the pathophysiology of EoE and how they are being utilized to change therapy in EoE.

A Distinct Esophageal mRNA Pattern Identifies Eosinophilic Esophagitis Patients With Food Impactions

Eosinophilic esophagitis (EoE), a Th2-type allergic immune disorder characterized by an eosinophil-rich esophageal immune infiltrate, is often associated with food impaction (FI) in pediatric patients but the molecular mechanisms underlying the development of this complication are not well understood. We aim to identify molecular pathways involved in the development of FI. Due to large variations in disease presentation, our analysis was further geared to find markers capable of distinguishing EoE patients that are prone to develop food impactions and thus expand an established medical algorithm for EoE by developing a secondary analysis that allows for the identification of patients with food impactions as a distinct patient population. To this end, mRNA patterns from esophageal biopsies of pediatric EoE patients presenting with and without food impactions were compared and machine learning techniques were employed to establish a diagnostic probability score to identify patients with food impactions (EoE+FI). Our analysis showed that EoE patients with food impaction were indistinguishable from other EoE patients based on their tissue eosinophil count, serum IgE levels, or the mRNA transcriptome-based p(EoE). Irrespectively, an additional analysis loop of the medical algorithm was able to separate EoE+FI patients and a composite FI-score was established that identified such patients with a sensitivity of 93% and a specificity of 100%. The esophageal mRNA pattern of EoE+FI patients was typified by lower expression levels of mast cell markers and Th2 associated transcripts, such as FCERIB, CPA3, CCL2, IL4, and IL5. Furthermore, lower expression levels of regulators of esophageal motility (NOS2 and HIF1A) were detected in EoE+FI. The EoE+FI -specific mRNA pattern indicates that impaired motility may be one underlying factor for the development of food impactions in pediatric patients. The availability of improved diagnostic tools such as a medical algorithm for EoE subpopulations will have a direct impact on clinical practice because such strategies can identify molecular inflammatory characteristics of individual EoE patients, which, in turn, will facilitate the development of individualized therapeutic approaches that target the relevant pathways affected in each patient.

Heterogeneity in Clinical, Endoscopic, and Histologic Outcome Measures and Placebo Response Rates in Clinical Trials of Eosinophilic Esophagitis: A Systematic Review

BACKGROUND & AIMS

Agents are being developed for treatment of eosinophilic esophagitis (EoE). However, it is not clear what outcome measures would best determine the efficacy and safety of these agents in clinical trials. We performed a systematic review of outcomes used in randomized placebo-controlled trials of EoE and we estimate the placebo response and rates of remission.

METHODS

We searched MEDLINE, Embase, CENTRAL, ClinicalTrials.gov, and the EU Clinical Trials Register from inception through February 20, 2018 for randomized controlled trials of pharmacologic therapies for EoE. Efficacy outcome definitions, measurement tools, and the proportion of patients responding to placebo were collected and stratified by based on histologic, endoscopic, and patient-reported outcomes.

RESULTS

We analyzed data from 22 placebo-controlled trials, comprising 1112 patients with EoE. Ten additional active registered trials were identified. Most published trials evaluated topical corticosteroid therapy (13/22, 59.1%). Histologic outcomes measuring eosinophil density and patient-reported outcomes were reported in 21/22 published trials (95.5%). No consistently applied definitions of histologic or patient-reported response or remission were identified. Endoscopic outcomes were described in 60% (12/20) of published trials. The EoE Endoscopic Reference Score is the most commonly applied tool for describing changes in endoscopic appearance. The median histologic response to placebo was 3.7% (range, 0%-31.6%) and the median rate of remission in patients given placebo was 0.0% (range, 0%-11.0%). The median patient-reported response to placebo was 14.4% (range, 8.6%-77.8%) and rate of remission in patients given placebo was 26.2% (range, 13.2%-35.7%).

CONCLUSIONS

In a systematic review of the literature, we found that no standardized definitions of histologic, endoscopic, or patient-reported outcomes are used to determine whether pharmacologic agents produce a response or remission in patients with EoE. A core outcome set is needed to reduce heterogeneity in outcome reporting and facilitate trial interpretation and comparison of results from trials.

Eosinophilic esophagitis: pathophysiology and its clinical implications

Classically, eosinophilic esophagitis is an antigen-mediated chronic disease distinct from gastroesophageal reflux disease. Eosinophilic esophagitis is an emerging clinical problem that is growing in recognition. It is characterized clinically by feeding dysfunction, dysphagia, and reflux-like symptoms. Histologically, eosinophilic esophagitis is identifiable by a dense epithelial eosinophilic infiltrate. Experimental modeling and clinical studies over the last decade have greatly improved mechanistic insights and led to improvements in clinical understanding and the assessment of therapeutic options for patients and their clinicians who manage this disease. Here, we review the clinicopathologic diagnostic criteria and our understanding of eosinophilic esophagitis as an allergic disease with genetic and immunological components. We present studies defining the importance of the epithelial barrier and the concept of barrier dysfunction as an initiating or perpetuating factor for this disease. We discuss the relationship between the symptoms of dysphagia and feeding dysfunction, our current knowledge of the underlying pathophysiologic mechanisms, and advances in clinical assessment of esophageal distensibility and narrowing in eosinophilic esophagitis patients. Finally, therapeutic implications relating to the advances that have led to our current understanding of the pathophysiology of eosinophilic esophagitis are explored.

Pediatric Eosinophilic Esophagitis Endotypes: Are We Closer to Predicting Treatment Response?

Eosinophilic esophagitis (EoE) is a chronic, food antigen-driven gastrointestinal disease that is characterized by esophageal eosinophilia. Currently, there are no Food and Drug Administration (FDA)-approved treatments for EoE, but the two most commonly prescribed therapies include topical corticosteroids and food elimination diets. Clinical trials have revealed a significant proportion of cases that are resistant to topical corticosteroids, and although we define EoE as a food antigen-driven disease, not all patients with EoE respond to elimination diets or even elemental diets. The varied response to treatments highlights the heterogeneity of EoE and the need for new treatment strategies. Despite the clinical differences in treatment response, predicting the outcome remains difficult since factors including age, histologic severity at diagnosis, atopic history, and anthropometrics are not predictive of treatment response. In our practice at an academic pediatric referral center, we observe distinct clinical EoE phenotypes, including cases with atopy, connective tissue disorders, or responsiveness to a proton pump inhibitor. Similar to the work in progress with asthma, stratification of patients with EoE by clinical phenotypes and/or molecular endotypes will likely assist with therapy selection and prediction of natural history. Molecular analysis with gene expression panels also shows promise in helping us classify patients based on molecular endotypes. In additional to the clinical and molecular classifications, more accurate histologic diagnostic criteria for EoE may help us tease out small differences between patient cohorts. Despite the leaps in knowledge over the past decade regarding EoE pathogenesis, it remains a challenge to predict the response to treatment. Future studies focused on molecular, genetic, and immunologic analyses of larger patient cohorts are needed to assist in identifying EoE phenotypes and endotypes as we attempt to improve patient outcomes in pediatric EoE.

Does Aeroallergen Sensitization Cause or Contribute to Eosinophilic Esophagitis?

Eosinophilic esophagitis is an atopic disease defined clinically by esophageal symptoms in combination with a dense esophageal eosinophilia. EoE is triggered and maintained by exposure to certain foods and it is known that dietary modification controls symptoms and achieves disease remission. Recently, aeroallergens have been implicated in the pathogenesis of EoE. To examine the role of aeroallergens in EoE, we reviewed the published literature. Sensitization and production of IgE antibodies to foods and aeroallergens in subjects with EoE has been demonstrated. However, the evidence suggests only a minor role for IgE-mediated immune reactions in EoE. There is some evidence to support an association of EoE diagnosis and flares with environmental allergen exposure, and animal studies support the notion that EoE may be induced by exposure to inhalant allergens. Some studies show that newly diagnosed cases of EoE follow a seasonal pollen distribution (summer and spring), but the weight of evidence does not support the seasonal occurrence of diagnosis or worsening of symptoms. Overall, we conclude that the current evidence does not support causality in inhalant allergen exposure and the genesis nor exacerbations of EoE in humans, although there is a possibility that inhalant allergen sensitization could play a modifying role in EoE in the context of cross-reacting food allergens.

Monoclonal Antibodies for Treatment of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the esophagus affecting both children and adults, with debilitating and progressive symptoms. EoE has shown an explosive epidemiological rise in the past few decades. Many patients experience a poor level of disease control despite maximal use of available guideline-based therapies, which seriously hampers their quality of life. Diet restrictions and systemic and topical corticosteroids are the current mainstays of EoE therapy, but are associated with significant efficacy, treatment compliance, and safety issues such as oral or esophageal candidiasis, growth retardation, osteopenia, osteoporosis, glucose intolerance, and cataract formation. As EoE is a chronic inflammatory disease, immune cells and cytokines are responsible for the inflammatory response and symptoms. Monoclonal antibodies specifically targeting these pathophysiologic effectors offer more potent relief of histologic and clinical disease features while keeping off-target adverse effects to a minimum. Herein, we have reviewed the current evidence regarding efficacy and safety of monoclonal antibodies including mepolizumab (anti-IL-5), reslizumab (anti-IL-5), QAX576 (anti-IL-13), omalizumab (anti-immunoglobulin-E), and infliximab (anti-TNF-α) in treatment of EoE. Our review indicates that although the use of monoclonal antibodies for EoE treatment is safe with limited and reversible adverse events, however, it is not yet possible to reach a final verdict on the efficacy of mAbs in EoE. Future well-designed studies are needed to clarify the exact role of mAbs in EoE.

Pathophysiology of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the esophagus associated with an atopic predisposition which appears to be increasing in prevalence over the last few decades. Symptoms stem from fibrosis, swelling, and smooth muscle dysfunction. In the past two decades, the etiology of EoE has been and is continuing to be revealed. This review provides an overview of the effects of genetics, environment, and immune function including discussions that touch on microbiome, the role of diet, food allergy, and aeroallergy. The review further concentrates on the pathophysiology of the disease with particular focus on the important concepts of the molecular etiology of EoE including barrier dysfunction and allergic hypersensitivity.

Eosinophilic Esophagitis: an Important Comorbid Condition of Asthma?

Eosinophilic esophagitis and asthma are frequently found as comorbid conditions in children and adults along with other manifestations of atopic diathesis. These two conditions have similar T helper 2 responses-driven pathophysiology and share common management strategies such as using systemic corticosteroids and targeted anti-cytokine biologic therapies. Review of the literature finds that asthma is often a comorbid condition in eosinophilic esophagitis in both children and adults; however, the EoE-asthma relationship remains poorly characterized mechanistically and clinically. EoE and asthma commonly share several comorbid conditions such as allergic rhinitis and gastroesophageal reflux disease; therefore, addressing these comorbid conditions has the potential to improve and/or maintain control in both diseases. Similar to asthma, patients with EoE frequently demonstrate elevations in serum markers of atopy, including serum IgE levels, peripheral eosinophil counts, and T helper 2-related cytokines. Gastroesophageal reflux disease is thought to affect asthma through microaspirations, airway hyperresponsiveness, and increased vagal tone. The understanding of the relationship between gastroesophageal reflux and EoE is still evolving but seems to be bidirectional and interactive. In terms of treatment, similar classes of medications have been used in both EoE and asthma. In both children and adults, EoE remission can be achieved by food trigger avoidance and use of corticosteroids and biologic therapies. Asthma control is mostly achieved through inhaled corticosteroids, and long but biologic therapies are increasingly used in severe subsets of the disease. Significant clinical and mechanistic work needs to be accomplished to better understand the relationship between asthma, EoE, and their interaction with other allergic diseases. Understanding whether shared mechanisms exist can lead to the development of new diagnostic and therapeutic strategies. The following review examines the existing literature regarding prevalence, common comorbidities, and potential therapeutic approach and identifies gaps in knowledge and future directions.

Medical and dietary treatments in eosinophilic esophagitis

Eosinophilic esophagitis (EoE) refers to a relatively new chronic inflammatory disease of the esophagus, which according to the current understanding underlies an immune-mediated pathogenesis driven by exposure to allergens. While several open questions remain regarding ethiopathogenesis as well as treatment options and their positioning, one thing has increasingly been recognized. The disease is on the rise and will increasingly be of importance in everyday's clinical practice, not only in expert physicians but also gastroenterologists with a broad clinical spectrum, allergologists and even general practitioners. The aim of this review is to provide a current overview on EoE treatment, including the rationale and endpoints of treatment in EoE, medical treatment options - providing the standard of current care, second-line options and outlook to emerging therapies - as well as dietary elimination approaches.

Eosinophilic Esophagitis: Review and Update

Background: Eosinophilic esophagitis (EoE) was first described in the 1990s, showing an increasing incidence and prevalence since then, being the leading cause of food impaction and the major cause of dysphagia. Probably, in a few years, EoE may no longer be considered a rare disease. Methods: This article discusses new aspects of the pathogenesis, symptoms, diagnosis, and treatment of EoE according to the last published guidelines. Results: The epidemiological studies indicate a multifactorial origin for EoE, where environmental and genetic factors take part. EoE affects both children and adults and it is frequently associated with atopic disease and IgE-mediated food allergies. In patients undergoing oral immunotherapy for desensitization from IgE-mediated food allergy the risk of developing EoE is 2.72%. Barrier dysfunction and T-helper 2 inflammation is considered to be pathogenetically important factors. There are different patterns of clinical presentation varying with age and can be masked by adaptation habits. Besides, symptoms do not usually correlate with histologic disease activity. The diagnostic criteria for EoE has evolved but mainly requires symptoms of esophageal dysfunction with histologic evidence of a peak value of at least 15 eosinophils per high-power field. Endoscopies have to be repeated in order to diagnose, monitor, and treat EoE. Treatment of EoE can be started either by drugs (PPIs and topical corticosteroids) or elimination diets. The multistage step-up elimination diet management approach of EoE is promising. Endoscopic dilation is used for patients with severe dysphagia/food impaction with inadequate response to anti-inflammatory treatment. Conclusions: Research in recent years has contributed to a better understanding of EoE's pathogenesis, genetic background, natural history, allergy workup, standardization in assessment of disease activity, evaluation of minimally invasive diagnostic tools, and new therapeutic approaches. However, several unmet needs are to be solved urgently, as finding a non-invasive disease-monitoring methods and biomarkers for routine practice, the development or new therapies, novel food allergy testing to detect triggering foods, drug, and doses required for initial therapy and safety issues with long-term maintenance therapy, amongst others. Besides, multidisciplinary management units of EoE, involving gastroenterologists, pediatricians, allergists, pathologists, dietitians, and ENT specialists are needed.

Gastrointestinal and Extra-Intestinal Manifestations of IgG4-Related Disease

IgG4-related disease (IgG4-RD) is a chronic relapsing multi-organ fibro-inflammatory syndrome of presumed autoimmune etiology. It is characterized by increased serum levels of IgG4 and tissue infiltration by IgG4⁺ cells. Increased titers of autoantibodies against a spectrum of self-antigens and response to steroids have led to its characterization as an autoimmune disease. However, the pathognomonic antigens probably differ among manifestations, and different antigens or autoantibodies produce similar immune reactions in different organs. Little is known about the pathogenic effects, if any, of serum IgG4 or IgG4⁺ plasma cells in tissues. Despite several animal models of the disease, none truly recapitulates human IgG4-RD. Histologic analyses of tissues from patients with IgG4-RD reveal a dense lymphoplasmacytic infiltrate rich in IgG4⁺ plasma cells, storiform fibrosis, and obliterative phlebitis, although these features vary among organs. Typical presentation and imaging findings include mass-forming synchronous or metachronous lesions in almost any organ, but most commonly in the pancreas, bile duct, retroperitoneum, kidneys, lungs, salivary and lacrimal glands, orbit, and lymph nodes. In all organs, inflammation can be reduced by corticosteroids and drugs that deplete B cells, such as rituximab. Patients with IgG4-RD have relapses that respond to primary therapy. Intense fibrosis accompanies the inflammatory response, leading to permanent organ damage and insufficiency. Death from IgG4-RD is rare. IgG4-RD is a multi-organ disease with predominant pancreatico-biliary involvement. Despite its relapsing-remitting course, patients have an excellent prognosis.

Eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an atopic condition of the esophagus that has become increasingly recognized over the last 15 years. Diagnosis of the disorder is dependent on the patient’s clinical manifestations, and must be confirmed by histologic findings on esophageal mucosal biopsies. Patients with EoE should be referred to an allergist for optimal management, which may include dietary modifications and pharmacologic agents such as corticosteroids, and for the diagnosis and management of comorbid atopic conditions. Mechanical dilation of the esophagus may also be necessary. The epidemiology, pathophysiology, diagnosis, treatment, and prognosis of EoE are discussed in this review.

Nonesophageal Eosinophilic Gastrointestinal Disorders: Clinical Care and Future Directions

Eosinophilic gastrointestinal disorders are a set of conditions with a wide range of clinical manifestations and treatment modalities. The disorders are suspected to result from an abnormal inflammatory response to allergen (s), and individuals may develop a relapsing or chronic disease, if the allergen is not eliminated. Mechanisms of disease pathogenesis, including the humoral immune response, need to be fully elucidated. A variety of therapies are used, although there is a lack of well-defined randomized, prospective studies. Other therapeutic options are needed as the current treatments have potential concerns; elimination diets may impair a child's quality of life, and corticosteroids have adverse risks with long-term use. We review what is known about nonesophageal eosinophilic gastrointestinal disorders, and discuss research investigations which need to be conducted to facilitate diagnosis and enhance treatment methods.

Esophageal IgG4 levels correlate with histopathologic and transcriptomic features in eosinophilic esophagitis

BACKGROUND

Recent data associate eosinophilic esophagitis (EoE) with IgG4 rather than IgE, but its significance and function have not been determined. Our aims were to measure esophageal IgG4 levels and to determine functional correlations as assessed by histologic and transcriptome analyses.

METHODS

This case-control study included pediatric subjects with EoE (≥15 eosinophils/HPF) and non-EoE controls. Protein lysates were analyzed for IgA, IgM, and IgG1-IgG4 using the Luminex 100 system; IgE was quantified by ELISA. Esophageal biopsies were scored using the EoE histology scoring system. Transcripts were probed by the EoE diagnostic panel, designed to examine the expression of 96 esophageal transcripts.

RESULTS

Esophageal IgG subclasses, IgA, and IgM, but not IgE, were increased in subjects with EoE relative to controls. The greatest change between groups was seen in IgG4 (4.2 mg/g protein [interquartile range: 1.0-13.1 mg/g protein] vs 0.2 mg/g protein [0.1-0.9]; P < .0001). Tissue IgG4 levels correlated with esophageal eosinophil counts (P = .0006); histologic grade (P = .0011) and stage (P = .0112) scores; and IL4, IL10, IL13, but not TGFB1, expression and had strong associations with a subset of the EoE transcriptome. Esophageal IgG4 transcript expression was increased and correlated with IgG4 protein levels and IL10 expression.

CONCLUSION

These findings extend prior studies on IgG4 in adult EoE to the pediatric population and provide deeper understanding of the potential significance and regulation of IgG4, demonstrating that IgG4 is a relevant feature of the disease; is closely related to esophageal eosinophil levels, type 2 immunity and T regulatory cytokines; and is likely produced locally.

Eosinophilic Esophagitis and the Eosinophilic Gastrointestinal Diseases: Approach to Diagnosis and Management

The eosinophilic gastrointestinal diseases (EGIDs) represent disorders of the gastrointestinal (GI) tract that result from the local infiltration and aberrant activity of eosinophils and other immune cells. Eosinophilic esophagitis (EoE) is the most well-characterized EGID and is defined by the presence of intraepithelial eosinophils in the esophagus (≥15 eosinophils per high-powered field) and clinical symptoms associated with esophageal dysfunction. The other EGIDs are rare and lack strong data regarding pathogenesis and management. The incidence and prevalence of EoE are increasing, and EoE is now a major cause of upper GI morbidity. Management is multidisciplinary, with collaboration between gastroenterologists, allergists, pathologists, and dieticians, and is aimed at amelioration of symptoms and prevention of long-term complications such as esophageal stricture. Treatment options for EoE include proton pump inhibitors, swallowed topical corticosteroids, and elimination diets. Esophageal dilation is used when esophageal strictures or fibrostenotic changes are present. Additional therapies targeting eosinophils and other mediators of Th2 inflammation are under development and are promising. Treatment options for other EGIDs typically involve corticosteroids or dietary elimination.

Pediatric Eosinophilic Esophagitis Is Associated With Increased Lamina Propria Immunoglobulin G4-Positive Plasma Cells

OBJECTIVE

Eosinophilic esophagitis (EoE) is considered a TH2-mediated food allergy disease that leads to submucosal esophageal fibrosis and strictures. Recent studies focused on adults with EoE identified a strong association with elevated esophageal IgG4 immunostaining. Our study aimed to determine the association of IgG4 with EoE in pediatric patients.

METHODS

Using our local EoE research registry, we identified 41 adequate biopsies from EoE patients. We used 10 age- and sex-matched patients with no diagnostic abnormalities at endoscopy or on biopsy. Using a monoclonal antibody to Immunoglobulin G4 (IgG4), we determined the maximum density of IgG4-positive plasma cells (IgG4-PC) per high-power field (hpf). Using a semi-quantitative assessment, we also graded the noncellular staining of the lamina propria and epithelium.

RESULTS

Our EoE cohort consisted predominantly of boys with an average age of 5.9 years and 63% had a documented IgE-based food allergy. Median peak eosinophilia was 40 eosinophils/hpf and the median IgG4-PC density was 39/hpf in the active esophagitis patients, compared with a median of 0 IgG4-PC/hpf in the non-EoE patients (P = 0.0001). EoE patients with a food allergy showed a significantly higher IgG4-PC density (44.5/hpf) than those without a food allergy (8/hpf; P = 0.0385). There was no significant association between IgG4-PC density and peak eosinophilia (r = 0.0011).

CONCLUSIONS

We demonstrate that active esophagitis in pediatric EoE patients is associated with elevated levels of IgG4-positive plasma cells, which was more significant in EoE patients with a documented food allergy. Our study also adds to the growing literature that EoE may involve more than just an exaggerated TH2 immune response.

Minimally invasive biomarker studies in eosinophilic esophagitis: A systematic review

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic, inflammatory disease of the esophagus that currently requires repeated endoscopic biopsies for diagnosis and monitoring because no reliable noninvasive markers have been identified.

OBJECTIVE

To identify promising minimally invasive EoE biomarkers and remaining gaps in biomarker validation.

METHODS

We performed a systematic review of EMBASE, Ovid MEDLINE, PubMed, and Web of Science from inception to June 6, 2017. Studies were included if patients met the 2007 consensus criteria for EoE diagnosis, a minimally invasive biomarker was assessed, and the study included at least 1 control for comparison.

RESULTS

The search identified 2094 studies, with 234 reviewed at full-text level, and 49 included in the analysis (20 adult, 19 pediatric, 7 pediatric and adult, and 3 not stated). Most (26 of 49) were published after 2014. Thirty-five studies included healthy controls, 9 analyzed atopic controls, and 29 compared samples from patients with active and inactive EoE. Minimally invasive biomarkers were obtained from peripheral blood (n = 41 studies), sponge or string samples (n = 3), oral or throat swab secretions (n = 2), breath condensate (n = 2), stool (n = 2), and urine (n = 2). The most commonly reported biomarkers were peripheral blood eosinophils (n = 16), blood and string eosinophil granule proteins (n = 14), and eosinophil surface or intracellular markers (n = 12). EoE biomarkers distinguished active EoE from healthy controls in 23 studies, atopic controls in 2 studies, and inactive EoE controls in 20 studies.

CONCLUSION

Several promising minimally invasive biomarkers for EoE have emerged; however, few are able to differentiate EoE from other atopic diseases.

New developments in patients with eosinophilic gastrointestinal diseases presented at the CEGIR/TIGERS Symposium at the 2018 American Academy of Allergy, Asthma & Immunology Meeting

The Consortium of Eosinophilic Gastrointestinal Diseases and the International Gastrointestinal Eosinophil Researchers organized a day-long symposium at the recent 2018 Annual Meeting of the American Academy of Allergy, Asthma & Immunology, which was coupled for the first time with the World Allergy Organization meeting to create an international platform. The symposium featured experts in many facets of eosinophilic gastrointestinal diseases, including allergy, immunology, gastroenterology, pathology, and nutrition, and was a well-attended event. The basic science, genetics, cellular immunology, and clinical features of the diseases, with a focus on epithelial, eosinophil, and mast cell responses, as well as current and emerging treatment options, were reviewed. Here we briefly review some of the highlights of the material presented at the meeting.

Allergic components of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a disorder of increasing prevalence worldwide, causing clinical symptoms of vomiting, failure to thrive, and dysphagia and complications of esophageal remodeling with strictures and food impactions. Molecular profiling demonstrates EoE to be an eosinophil-predominant disorder with a TH2 cytokine profile reminiscent of other allergic diseases, such as asthma, allergic rhinitis, and atopic dermatitis. Environmental antigens in the form of foods and aeroallergens induce eosinophil, basophil, mast cell, and T-cell infiltration. Pathogenesis depends on local epithelial immune activation with production of thymic stromal lymphopoietin and eotaxin-3. Complications mirror asthmatic airway pathogenesis, with increases in subepithelial collagen deposition, angiogenesis, and smooth muscle hypertrophy. The removal of instigating antigens, especially foods, causes disease resolution in more than 50% of adults and children. The prevalence of concurrent atopic disorders in patients with EoE and the need to control antigen-specific TH2 inflammation underscore the importance of testing for allergens and treating the entire atopic subject to control the potential interplay between organ-specific allergic responses.

Environmental factors and eosinophilic esophagitis

The incidence and prevalence of eosinophilic esophagitis (EoE) have markedly increased over the past 2 decades, outpacing increased detection of the disease. Although genetic susceptibility markers for EoE have begun to be elucidated, the rate at which EoE has increased in incidence suggests environmental factors predominate. Despite many advances in understanding of the pathogenesis of EoE, the cause of EoE is unknown. This article reviews the emerging data related to environmental risk factors for EoE. Many of these environmental factors are rooted in the theoretical framework of the hygiene hypothesis, specifically mediation of disease development through dysbiosis. Other hypotheses are based on associations that have been observed in studies of non-EoE allergic disease. We describe the evidence that early-life exposures, including antibiotic use, acid suppression, and cesarean delivery, can increase the risk of disease. We also describe the evidence that infectious agents, such as Helicobacter pylori, are inversely associated with disease. Current evidence on geographic risk factors, such as population density, climate zone, and seasonality, is reviewed. We also describe behavioral factors that have been evaluated. Limitations of the existing research are discussed, and recommendations for future areas of research, including assessment of gene-environment interaction, are presented.

Biologic Agents for the Treatment of Hypereosinophilic Syndromes

Hypereosinophilic syndromes (HES) are a heterogeneous group of rare disorders defined by the presence of marked peripheral or tissue eosinophilia resulting in end-organ damage. Although conventional therapies, including glucocorticoids, hydroxyurea, and IFN-α, are initially effective in reducing eosinophilia and symptoms in a majority of patients with platelet-derived growth factor mutation-negative HES, the development of resistance and treatment-related toxicity are common. In contrast, targeted therapy with the tyrosine kinase inhibitor, imatinib, is well tolerated but effective only in the subset of patients with HES with a primary myeloid disorder. Eosinophil-targeted biotherapeutics offer the potential of improved efficacy with few, if any, adverse effects. The aims of this review are to provide an overview of current approaches to the use of conventional HES therapies and a discussion of existing biotherapeutics that target eosinophils and their potential use in the treatment of HES. With the continuing expansion of eosinophil-targeted biotherapeutics, the future for patients with eosinophilic disorders is promising.

Unproven Diagnostic Tests for Food Allergy

The gold standard for diagnosis of immunoglobulin E (IgE)-mediated food allergy remains the oral food challenge, with serum IgE testing and skin prick testing serving as acceptable alternatives. However, the increase in prevalence of food allergy (both physician diagnosed and patient suspected) has led patients to pursue a variety of other alternative diagnostic procedures for suspected food allergy, which are reviewed in this article. These procedures (IgG testing, electrodermal testing, cytotoxic testing, provocation/neutralization, and applied kinesiology) have largely been unproven and may lead to unnecessary elimination diets.

Highlights in immune response, microbiome and precision medicine in allergic disease and asthma

Several recent key findings in immunology of allergic diseases that have led to a need of reassessment of our current thinking are reviewed in this issue of the journal. Recently developed strong evidence on the role of hygiene hypothesis in protection from allergic disease and its immune mechanisms is reviewed by Ober et al. The authors pointed out immunologic mechanisms of lower prevalence of asthma and allergic sensitization observed among Amish children living on traditional farms with higher endotoxin levels as compared to Hutterite children living on industrialized farms. Barcik et al. reviewed that biologically active histamine in humans is produced by certain bacteria in the gut in addition to several cells, and has broad immunoregulatory functions. Turcanu et al. reviewed immune mechanisms of a revolutionary change to protect from food allergy. The immunologic window of opportunity in the infants can be used to enable oral tolerance in severe allergy predisposed children. Accordingly, van de Veen et al. reviewed general mechanisms of allergen tolerance highlighting recent findings. Extensive usage of precision medicine due to emerging biologics is knocking the doors of allergic diseases and asthma. Boyd et al. reviewed the existing and future "immune monitoring" approaches in the multiple omics perspective with the hope of identifying better correlates of disease status, predictors of therapeutic outcomes, and potential side-effects of treatment. Paul et al. reviewed newly uncovered innate and adaptive immunologic mechanisms that contribute to the pathogenesis of eosinophilic esophagitis. Further highlighting newly developing disease subgroups and precision medicine, Guttman-Yassky & Kruger reviewed clinical subtypes of atopic dermatitis and psoriasis, which may potentially benefit from newly developing highly efficient biologicals. Complementing this paper, Kabashima & Nomura reviewed similarities and distinctions in mouse models of atopic dermatitis and psoriasis.

Emerging drugs for eosinophilic esophagitis

INTRODUCTION

Eosinophilic esophagitis (EoE) is rare but incidence and prevalence is increasing. EoE is characterized by eosinophilic inflammation of the esophagus causing gastrointestinal symptoms such as abdominal pain, vomiting, reflux, dysphagia, and food impactions. If untreated, remodeling and fibrosis of the esophagus can occur and stricture formation may result. Current treatment options are limited to food-restriction diets or medications including proton pump inhibitors (PPIs) or swallowed corticosteroids. Significant progress has been made in understanding the underlying mechanisms of EoE allowing for development of drugs that target specific points in EoE pathways. Investigation of these drugs is early with few controlled studies, but many show promise as future treatments. Areas covered: This review will provide an up to date discussion of current therapies and investigational drugs for EoE. Articles used in this review were retrieved from PubMed. Ongoing or completed clinical trials were obtained through clinicaltrials.gov and review of the PharmaProjects database. Expert Opinion: Multiple therapeutic targets have been identified and several have shown efficacy. Work is needed to define appropriate trial outcome measures. Collaboration between government agencies, patient advocacy groups, and investigator-led consortia is critical for completing new clinical trials which should pave the way for new therapies in clinical practice.