Early life exposures as risk factors for pediatric eosinophilic esophagitis

Management of Eosinophilic Esophagitis During Pregnancy

There are currently limited data on the management of eosinophilic esophagitis (EoE) during pregnancy. At our center, however, we have followed several pregnant women with EoE and others have asked pertinent questions in pre-pregnancy counseling. The relatively young age of patients with EoE implies that many practitioners will also encounter patients with these questions. In this review, we use four cases to prompt a discussion about concerns focused on the safety of steroids and diet therapy during pregnancy and breast-feeding, potential nutritional risks with dietary elimination, how to optimize therapy, and whether endoscopic evaluation for monitoring of disease activity is safe during pregnancy and breast-feeding. An additional concern is whether the disease could progress during pregnancy and breast-feeding if no therapies are used. Although there are no studies specifically examining pregnant EoE patients, we have reviewed the literature relevant to this population as informed by the treatment of inflammatory bowel disease patients during pregnancy, where these issues have been studied in more depth. Providers who care for EoE patients who could become pregnant should familiarize themselves with these issues.

Eosinophilic Esophagitis, Eosinophilic Gastroenteritis, and Eosinophilic Colitis: Common Mechanisms and Differences between East and West

Background

Eosinophilic esophagitis (EoE), eosinophilic gastroenteritis (EGE), and eosinophilic colitis (EoC) have been diagnosed with an increasing frequency over the last decades. All these diseases share pathogenic similarities with respect to triggering by food antigens in the majority of patients once secondary causes of tissue eosinophilia have been excluded. While diagnostic criteria for EoE have been published, the exact criteria for EGE and EoC still need to be defined. This review highlights similarities and differences between affected patients when comparing the Western with the Eastern world.

Summary

The incidence and prevalence of EoE are on the rise in countries from the Western and Eastern world. Very limited epidemiologic data exist regarding EGE and EoC. Characteristics of patients with eosinophilic gastrointestinal disorders regarding gender distribution, age at diagnosis, and associated comorbidities are similar when comparing Eastern with Western countries. Similar modalities are applied to diagnose EoE, EGE, and EoC when comparing Eastern with Western countries. Additionally, comparable therapeutic measures are applied to treat eosinophilic gastrointestinal diseases in Eastern and Western countries. While EoE treatment recommendations are based on increasingly solid evidence, recommendations for the treatment of EGE and EoC are based on low evidence.

Key Messages

Eosinophilic gastrointestinal diseases are diagnosed and treated using similar approaches in Eastern and Western countries. Further efforts should be undertaken to help clarify the underlying pathogenic mechanisms and to establish evidence-based diagnostic and therapeutic protocols.

Assessing Early Life Factors for Eosinophilic Esophagitis: Lessons From Other Allergic Diseases

OPINION STATEMENT

Few studies have been conducted to investigate possible early life determinants for eosinophilic esophagitis. An improved understanding of the etiologic factors implicated in disease development would further elucidate possible disease pathogenesis, inform therapeutic targets for disease treatment, and identify possible modifiable factors for disease prevention in genetically susceptible individuals. Although eosinophilic esophagitis is increasing in incidence and prevalence, the disease remains relatively rare, posing challenges for studying etiologic factors in disease development. Eosinophilic esophagitis is believed to be antigen-mediated, and most patients with EoE have concomitant atopic disease. In recent years, the evolution of our understanding of possible etiologic mechanisms in allergic disease has been informed by our understanding of how early life perturbations can lead to dysbiosis in the colonization of the microflora in the gastrointestinal tract and subsequent dysregulated immune development. Perturbations include factors such as antibiotic use, including prenatal, intra-antepartum, and infancy use of antibiotics, Cesarean delivery, preterm delivery, and neonatal intensive care admission. This article provides a review of these recent developments, as they relate to atopic disease, to inform future directions in the study of early life etiologic factors in the development of eosinophilic esophagitis.

Mechanisms of Disease of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a recently recognized inflammatory disease of the esophagus with clinical symptoms derived from esophageal dysfunction. The etiology of EoE is now being elucidated, and food hypersensitivity is emerging as the central cornerstone of disease pathogenesis. Herein, we present a thorough picture of the current clinical, pathologic, and molecular understanding of the disease with a focus on disease mechanisms.

Recent research advances in eosinophilic esophagitis

PURPOSE OF REVIEW

Eosinophilic esophagitis (EoE) is a chronic allergic disease triggered by food allergens with an increasing prevalence. This review highlights recent research advances in EoE with a focus on the literature of the past 18 months.

RECENT FINDINGS

The incidence of EoE in the black population is higher than previously suggested. A novel locus spanning CAPN14 is associated with EoE. Diagnostic tests utilizing an analysis of EoE-specific transcriptome have been improved. Standardized EoE symptom score systems have been established. Treatment trials show the promise and limitations of allergen avoidance, antiinflammatory reagents, and anti-interleukin-13 antibodies. Insights into disease mechanisms highlight the role of invariant natural killer T cells and group 2 innate immune cells. Epithelial barrier protein desmoglein 1, bone morphogenetic protein antagonist follistatin, neurotrophic tyrosine kinase receptor type 1, and CAPN14 have been defined as new potential therapeutic targets in EoE as regulators of the inflammatory interleukin-13-axis. The role of IgG4 in the disease mechanisms has been suggested.

SUMMARY

Genetic predisposition influenced by environmental factors increases EoE susceptibility. Research identifying the critical events leading to allergen sensitization and the esophagus-specific responses that drive EoE is evolving, and will lead to a better understanding of EoE and new therapeutic approaches for the disease.

Seasonal distribution of initial diagnosis and clinical recrudescence of eosinophilic esophagitis: a systematic review and meta-analysis

BACKGROUND

The association between seasonality and diagnosis and/or recrudescence of eosinophilic esophagitis (EoE) remains unclear, with some studies demonstrating a higher diagnostic rate in those months with a higher aeroallergen load while others rule out this association.

METHODS

We performed a systematic search of the MEDLINE, EMBASE, and SCOPUS databases for studies on the seasonality of the initial diagnosis or recrudescence (i.e., food bolus impaction) of EoE. Summary estimates, including 95% confidence intervals, were calculated for seasonal variation in diagnosis or incidence of food bolus impaction. A random-effects meta-regression model was made using aggregate-level data to compare seasonality in EoE diagnosis and recrudescence. Publication bias risks were assessed by means of funnel plot analysis.

RESULTS

Of 1078 references found, data were finally collected from 18 studies which included a total of 16,846 EoE patients. Of all new cases of EoE diagnosed per year, 27.1% were diagnosed in spring and 21.5% in winter. No overall statistical differences in the annual seasonal distribution of newly diagnosed EoE cases were observed in the random-effects meta-regression model (P = 0.132). Similarly, a homogenous distribution of episodes of EoE recrudescence throughout the year was noted, with no significant differences between seasons (P = 0.699). No significant publication bias was found.

CONCLUSIONS

This systematic review found no significant variations in the seasonal distribution of either the diagnosis or clinical recrudescence of EoE throughout the year.

Role of Environmental Factors in the Development of Pediatric Eosinophilic Esophagitis

BACKGROUND

Despite accumulating data on the pathogenesis of eosinophilic esophagitis, not much is known about risk factors for the development of the disease. The role of factors such as smoking, breastfeeding, early antibiotic exposure and other factors that have been associated with other allergic diseases has not been well studied in children with eosinophilic esophagitis.

AIM

To explore the role of environmental and medication exposures in the development of pediatric eosinophilic esophagitis.

METHODS

We conducted a cross-sectional case-control study, utilizing a parent and child questionnaire and medical chart review. Urine cotinine levels, measured by high-performance liquid chromatography, were obtained as objective evidence for smoking exposure.

RESULTS

One hundred and two children with eosinophilic esophagitis and 167 controls were recruited. The controls were mainly diagnosed with functional gastrointestinal disorders (33%) and gastroesophageal reflux disease (29%). Food allergy, specifically for peanuts and tree nuts, and allergy to pollen, tree, and grass were significantly higher among eosinophilic esophagitis children. Smoking exposure, both primary and secondary, was not associated with pediatric eosinophilic esophagitis when compared to controls (odds ratio 0.96, 95% confidence interval 0.58-1.59). Furthermore, early smoking exposure in the first year of life was higher among controls. Common accepted risk factors for allergy and atopy, such as breastfeeding practices, antibiotics exposure, animals' exposure, and others, were not found to be associated with eosinophilic esophagitis in our study.

CONCLUSION

Common risk factors in other allergic and atopic conditions were not found to be associated with eosinophilic esophagitis.

Eosinophilic Esophagitis

Once considered a rare condition, eosinophilic esophagitis is now one of the most common conditions diagnosed during the assessment of feeding problems in children and during the evaluation of dysphagia and food impaction in adults. The entity exists worldwide but has been most extensively studied in Western countries, where its prevalence has been estimated to be 0.4% among all children and adults. Whether eosinophilic esophagitis is truly a new disease or simply a recently recognized one is uncertain. In this review, we consider the diagnostic criteria, pathophysiological and clinical features, and treatment of this increasingly prevalent disease.

Insights into the emerging epidemic of eosinophilic oesophagitis

Eosinophilic oesophagitis (EOE) is a relatively recently recognised condition characterised by an increase in oesophageal eosinophils. EOE occurs in children and adults with a strong male preponderance. There has been a sharp increase in EOE in North America, Europe and Australia. The reasons for this increase remain unclear but are likely to be influenced by genetic and environmental factors, as well as early-life exposures. Based on recent population-based data, the estimated EOE prevalence in the USA is 56.7 per 100,000 persons. The peak prevalence was observed in patients between 35 and 39 years of age. Prevalence figures in Asia and the Middle East generally appear to be lower than in Western countries, but population-based studies are not available. A causal association between coeliac disease and EOE appears unlikely. Data on the seasonal variation of EOE remain inconclusive. Further population-based studies are needed to define the epidemiology of EOE.

Disease associations in eosinophilic oesophagitis and oesophageal eosinophilia

Eosinophilic infiltration into oesophageal tissue, typical of eosinophilic oesophagitis (EoE), has been described in several other conditions, including infections, hypersensitivity, and other autoimmune disorders. Since its description, EoE has been associated with an increasing number of diseases also characterized by tissue infiltration, including eosinophilic gastroenteritis and Crohn's disease. While an association between EoE and coeliac disease was previously reported, it is not supported by recent research. In contrast, EoE seems to be common in patients with a history of congenital oesophageal atresia, leading to hypotheses linking both disorders. The prevalence of EoE has also been shown to be eight times higher in patients with connective tissue disorders (CTDs), which has led to the proposal of an EoE-CTD phenotype, although this requires further assessment. This paper reviews the evidence of EoE's associations with several disorders, defining the common bases from an epidemiological, clinical, molecular and genetic perspective whenever possible.

The Role of Environmental Exposures in the Etiology of Eosinophilic Esophagitis: A Systematic Review

Eosinophilic esophagitis (EoE) is an emerging clinicopathologic entity defined by abnormal esophageal eosinophilic infiltration. Management of this disease is hampered by limited understanding of etiologic and controllable risk factors. The aim of this systematic review was to determine the environmental risk factors for EoE. We searched the PubMed, Web of Science, and EMBASE databases from January 1, 1950, through June 30, 2015. To identify additional relevant studies, we hand searched bibliographies of included articles. We limited the review to articles using human subjects and consisting of case reports, case series, cross-sectional and cohort studies, and clinical trials. Nineteen articles discuss the risk of environmental exposures on EoE and indicate that environment plays a large role in the etiology of EoE. Seasonal, geographic, and climate-based differences in disease prevalence have been reported, but the exact mediators of this process, possibly aeroallergens that vary over time and from place to place, remain elusive.

Environmental and infectious factors in eosinophilic esophagitis

Identifying possible environmental or infectious etiologic factors for eosinophilic esophagitis (EoE) may offer insight into opportunities for disease prevention and treatment. We reviewed the current literature to assess environmental and infectious factors evaluated in EoE. Few studies have been conducted, however a consistent inverse association between EoE and H. pylori has been described. Several studies suggest a weak association between season and EoE diagnosis, but the evidence is inconclusive. EoE has also been associated with early life factors, including Cesarean delivery and antibiotic use. Larger studies are needed to evaluate these associations more thoroughly. Several papers have speculated the potential for anti-secretory agents to contribute to EoE. This has not been formerly evaluated. In summary, there is significant opportunity in the future to advance our understanding of possible environmental etiologic factors for EoE.

Allergic mechanisms of Eosinophilic oesophagitis

Eosinophilic oesophagitis (EoE) is characterized by oesophageal dysfunction and oesophageal eosinophilia refractory to proton-pump-inhibitor treatment. EoE is a food allergy, as elimination of food trigger(s) abrogates the disease, while trigger reintroduction causes recurrence. The allergic mechanism of EoE involves both IgE and non-IgE processes. There is a break in oral tolerance, the immune mechanism allowing enteric exposure to food and micro-organisms without causing deleterious immune responses. Changes in life-style, alterations in gut flora and use of antibiotics may be increasing disease prevalence. Mouse models of EoE and human studies revealed the role of regulatory T-cells and iNKT-cells in the pathogenesis. Th2-cytokines like IL-4, IL-5 and IL-13, and other cytokines like TGFβ and TSLP are involved, but perhaps no one cytokine is critically important for driving the disease. Control of EoE may require a pharmaceutical approach that blocks more than one target in the Th2-inflammatory pathway.

Do We Know What Causes Eosinophilic Esophagitis? A Mechanistic Update

The mechanisms underlying eosinophilic esophagitis (EoE) have been intensely investigated, and significant advances have been made in understanding the pathogenesis of EoE. EoE is defined as a chronic immune/antigen-mediated disease, characterized clinically by symptoms of esophageal dysfunction and histologically by an esophageal eosinophilic infiltrate. In this paper, we will review the current knowledge of EoE pathophysiology based on both animal and human data and discuss possible etiologic mechanisms from the genetic and environmental perspectives. EoE is a Th2-predominant inflammatory process triggered by allergens. Proinflammatory cytokines and chemokines recruit eosinophils and other effector cells, such as mast cells, into the esophageal epithelium, where they cause direct damage and promote esophageal remodeling. The genetic expression profile of EoE has been described, and several single nucleotide polymorphisms have been identified and associated with EoE. While this genetic contribution is important, it is difficult to postulate that EoE is primarily a genetic disease. Given the rapid epidemiologic changes in the incidence and prevalence of EoE over the past two decades, environmental factors may be the driving force. While it is not known what causes EoE in an individual patient at a specific time, the current hypothesis is that there is a complex interaction between genetic factors and environmental exposures that remains to be elucidated.

Molecular pathogenesis of eosinophilic esophagitis

PURPOSE OF REVIEW

Eosinophilic esophagitis (EoE) is an esophageal disease characterized by an accumulation of eosinophils in the esophagus, which is normally devoid of eosinophils. The interest of the scientific community in EoE has grown considerably over the past two decades, and understanding of the molecular mechanisms involved in this disease has increased greatly in the last 2 years.

RECENT FINDINGS

Important new insights into the pathogenesis of EoE recently have been achieved. Recent evaluations considering genetic and the environmental risk factors have led to the concept that some still-unknown environmental factors influence the risk of developing EoE more than the genetic predisposition. New molecules (in addition to interleukin-13, eotaxin-3, transforming growth factor-β1, thymic stromal lymphopoietin, filaggrin, or interleukin-5) also have been shown to be involved in the disease pathogenesis.

SUMMARY

The present review describes recent advances in the understanding of the molecular mechanisms underlying EoE, and how these new findings have enhanced understanding of the pathogenesis of this new esophageal disorder.

Molecular, genetic, and cellular bases for treating eosinophilic esophagitis

Eosinophilic esophagitis (EoE) was historically distinguished from gastroesophageal reflux disease on the basis of histology and lack of responsiveness to acid suppressive therapy, but it is now appreciated that esophageal eosinophilia can respond to proton pump inhibitors. Genetic and environmental factors contribute to risk for EoE, particularly early-life events. Disease pathogenesis involves activation of epithelial inflammatory pathways (production of eotaxin-3 [encoded by CCL26]), impaired barrier function (mediated by loss of desmoglein-1), increased production and/or activity of transforming growth factor-β, and induction of allergic inflammation by eosinophils and mast cells. Susceptibility has been associated with variants at 5q22 (TSLP) and 2p23 (CAPN14), indicating roles for allergic sensitization and esophageal specific protease pathways. We propose that EoE is a unique disease characterized by food hypersensitivity; strong hereditability influenced by early-life exposures and esophageal-specific genetic risk variants; and allergic inflammation and that the disease is remitted by disrupting inflammatory and T-helper type 2 cytokine-mediated responses and through dietary elimination therapy.

Translating new developments in eosinophilic esophagitis pathogenesis into clinical practice

OPINION STATEMENT

New developments in eosinophilic esophagitis (EoE) pathogenesis are shaping our current therapeutic and management strategies. EoE is a chronic allergic inflammatory disease with progression to fibrostenotic disease. The disease warrants early diagnosis and long-term maintenance therapy. The diagnosis of EoE should be based on the concept of an allergy-mediated disease with esophageal dysfunction and esophageal eosinophilia. Recent findings suggest that proton pump inhibitor (PPI)-responsive esophageal eosinophilia (PPI-REE) is likely a continuum of EoE or a similar T-helper 2 (Th2)-mediated allergic process. PPIs have therapeutic properties that can benefit both gastroesophageal reflux disease (GERD) and EoE. Therefore, PPIs should be considered not a diagnostic tool but, rather, a therapeutic option for EoE. If patients are PPI nonresponsive, then dietary therapy or steroid therapy should be considered. Dilation can be reserved as adjuvant therapy for severe fibrostenotic lesions.

Recent advances in the pathological understanding of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergen-mediated inflammatory disease of the esophagus. This inflammation leads to feeding difficulties, failure to thrive and vomiting in young children, and causes food impaction and esophageal stricture in adolescents and adults. In the 20 years since EoE was first described, we have gained a great deal of knowledge regarding the genetic predisposition of disease, the inflammatory milieu associated with EoE and the long-term complications of chronic inflammation. Herein, we summarize the important breakthroughs in the field including both in vitro and in vivo analysis. We discuss insights that we have gained from large-scale unbiased genetic analysis, a multitude of genetically and chemically altered mouse models of EoE and most importantly, the results of clinical trials of various pharmacologic agents. Understanding these successes and failures may be the key to developing more effective therapeutic strategies.

Advances in clinical management of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic immune/antigen-mediated clinicopathologic condition that has become an increasingly important cause of upper gastrointestinal morbidity in adults and children over the past 2 decades. It is diagnosed based on symptoms of esophageal dysfunction, the presence of at least 15 eosinophils/high-power field in esophageal biopsy specimens, and exclusion of competing causes of esophageal eosinophilia, including proton pump inhibitor-responsive esophageal eosinophilia. We review what we have recently learned about the clinical aspects of EoE, discussing the clinical, endoscopic, and histological features of EoE in adults and children. We explain the current diagnostic criteria and challenges to diagnosis, including the role of gastroesophageal reflux disease and proton pump inhibitor-responsive esophageal eosinophilia. It is also important to consider the epidemiology of EoE (with a current incidence of 1 new case per 10,000 per year and prevalence of 0.5 to 1 case per 1000 per year) and disease progression. We review the main treatment approaches and new treatment options; EoE can be treated with topical corticosteroids, such as fluticasone and budesonide, or dietary strategies, such as amino acid-based formulas, allergy test-directed elimination diets, and nondirected empiric elimination diets. Endoscopic dilation has also become an important tool for treatment of fibrostenotic complications of EoE. There are a number of unresolved issues in EoE, including phenotypes, optimal treatment end points, the role of maintenance therapy, and treatment of refractory EoE. The care of patients with EoE and the study of the disease span many disciplines; EoE is ideally managed by a multidisciplinary team of gastroenterologists, allergists, pathologists, and dieticians.

Twin and family studies reveal strong environmental and weaker genetic cues explaining heritability of eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic antigen-driven allergic inflammatory disease, likely involving the interplay of genetic and environmental factors, yet their respective contributions to heritability are unknown.

OBJECTIVE

To quantify the risk associated with genes and environment on familial clustering of EoE.

METHODS

Family history was obtained from a hospital-based cohort of 914 EoE probands (n = 2192 first-degree "Nuclear-Family" relatives) and an international registry of monozygotic and dizygotic twins/triplets (n = 63 EoE "Twins" probands). Frequencies, recurrence risk ratios (RRRs), heritability, and twin concordance were estimated. Environmental exposures were preliminarily examined.

RESULTS

Analysis of the Nuclear-Family-based cohort revealed that the rate of EoE, in first-degree relatives of a proband, was 1.8% (unadjusted) and 2.3% (sex-adjusted). RRRs ranged from 10 to 64, depending on the family relationship, and were higher in brothers (64.0; P = .04), fathers (42.9; P = .004), and males (50.7; P < .001) than in sisters, mothers, and females, respectively. The risk of EoE for other siblings was 2.4%. In the Nuclear-Family cohort, combined gene and common environment heritability was 72.0% ± 2.7% (P < .001). In the Twins cohort, genetic heritability was 14.5% ± 4.0% (P < .001), and common family environment contributed 81.0% ± 4% (P < .001) to phenotypic variance. Probandwise concordance in monozygotic co-twins was 57.9% ± 9.5% compared with 36.4% ± 9.3% in dizygotic co-twins (P = .11). Greater birth weight difference between twins (P = .01), breast-feeding (P = .15), and fall birth season (P = .02) were associated with twin discordance in disease status.

CONCLUSIONS

EoE RRRs are increased 10- to 64-fold compared with the general population. EoE in relatives is 1.8% to 2.4%, depending on relationship and sex. Nuclear-Family heritability appeared to be high (72.0%). However, the Twins cohort analysis revealed a powerful role for common environment (81.0%) compared with additive genetic heritability (14.5%).

Antibiotic use and misuse during pregnancy and delivery: benefits and risks

Although pregnancy is considered as a physiological state, most pregnant women in developed countries receive multiple medications to prevent maternal or neonatal complications, with antibiotics among the most frequently prescribed. During pregnancy, antibiotics are often prescribed in the context of preterm labor, intrapartum fever, prevention of neonatal Group B Streptococcus fever, and cesarean section. Outside this period, they are commonly prescribed in the community setting for respiratory, urinary, and ear, nose and throat infection symptoms. Whereas some of the current indications have insightful reasons to justify their use, potential risks related to overuse and misuse may surpass the benefits. Of note, the recent 2014 World Health Assembly expressed serious concern regarding antibiotic resistance due to antibiotic overuse and misuse and urged immediate action to combat antibiotic resistance on a global scale. Most studies in the obstetrics field have focused on the benefits of antibiotics for short-term maternal and neonatal complications, but with very little (if any) interest in long-term consequences.

Cellular and molecular immunological mechanisms in eosinophilic esophagitis: an updated overview of their clinical implications

Eosinophilic esophagitis (EoE) is a pathophysiologically complex disorder driven by distinct, multiple mechanisms involving a large number of cells, molecules, and genes. Associated with food allergy from its initial descriptions, a key role for the Th2-type cytokines IL-5 and IL-13 in recruiting and activating eosinophils has been described. Epithelial cells have been recognized as major effectors in initiating EoE, both through their recruitment of iNKT cells towards the esophageal epithelium, which constitutes a major cytokine source, and through the release of eotaxin-3 and other chemoattractants. Epithelial and mesenchymal-released TSLP is a key regulator for which a connecting role between the adaptive and innate mucosal-associated immune response has been suggested. Finally, activated eosinophil- and mast cell-derived TGF β1 secretion is crucial in EoE-associated tissue remodeling.

Allergic mechanisms in eosinophilic esophagitis

Eosinophilic esophagitis is rapidly increasing in incidence. It is associated with food antigen-triggered, eosinophil-predominant inflammation, and the pathogenic mechanisms have many similarities to other chronic atopic diseases. Studies in animal models and from patients have suggested that allergic sensitization leads to food-specific IgE and T-helper lymphocyte type 2 cells, both of which seem to contribute to the pathogenesis along with basophils, mast cells, and antigen-presenting cells. In this review our current understandings of the allergic mechanisms that drive eosinophilic esophagitis are outlined, drawing from clinical and translational studies in humans as well as experimental animal models.

Epidemiology of eosinophilic esophagitis

In this article, the epidemiology of eosinophilic esophagitis (EoE) is reviewed. Demographic features and natural history are described, the prevalence and incidence of EoE are highlighted, and risk factors for EoE are discussed. EoE can occur at any age, there is a male predominance, it is more common in whites, and there is a strong association with atopic diseases. EoE is chronic, relapses are frequent, and persistent inflammation increases the risk of fibrostenotic complications. The prevalence is currently estimated at 0.5-1 in 1000, and EoE is now the most common cause of food impaction. The incidence of EoE is approximately 1/10,000 new cases per year, and the increase in incidence is outpacing increases in recognition and endoscopy volume, but the reasons for this evolving epidemiology are not yet fully delineated.

Genetic and epigenetic underpinnings of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a complex, polygenic disorder caused by genetic predisposition and environmental exposures. Because of the recent emergence of EoE as a bona fide global health concern, a paucity of available therapeutic and diagnostic options exists. However, rapid progress has been made in an effort to rectify this lack and to improve understanding of the factors that cause EoE. This article highlights key advances in elucidating the genetic (and epigenetic) components involved in EoE.

Involvement of the iNKT cell pathway is associated with early-onset eosinophilic esophagitis and response to allergen avoidance therapy

OBJECTIVES

Recent experimental evidence suggests that environmental microbial factors early in life determine susceptibility to allergic diseases through inappropriate chemotaxis and local activation of CD1d-restricted, invariant chain natural killer T (iNKT) cells. In this study, we analyzed the involvement of these pathways in pediatric patients with eosinophilic esophagitis (EoE) before and after dietary allergen elimination.

METHODS

mRNA expression levels of components of the C-X-C motif chemokine ligand 16 (CXCL16)-iNKT-CD1d axis were compared in esophageal biopsies from EoE patients vs. normal or inflammatory controls and before and after treatment.

RESULTS

CXCL16, iNKT cell-associated cell marker Vα24, and CD1d were significantly upregulated in esophageal biopsies from EoE patients and correlated with the expression of inflammatory mediators associated with allergy. Upregulation of each of these factors was significantly more pronounced in patients aged <6 years at diagnosis, and this early-onset EoE subpopulation was characterized by a more prominent food allergic disease phenotype in a cohort-wide analysis. Successful, but not unsuccessful, treatment of early-onset EoE patients with dietary elimination of instigating allergens led to reduction in infiltrating iNKT cells and complete normalization of mRNA expression levels of CXCL16 and CD1d.

CONCLUSIONS

Our observations place iNKT cells at the center of allergic inflammation associated with EoE, which could have profound implications for our understanding, treatment and prevention of this and other human allergic diseases.

Eosinophilic oesophagitis: clinical presentation and pathogenesis

Eosinophilic oesophagitis (EoE) is an inflammatory disorder of the oesophagus which has become increasingly recognised over recent years, although it remains underdiagnosed in many centres. It is characterised histologically by a significant eosinophilic infiltration of the oesophageal mucosa (>15 eosinophils per high powered field), and clinically with features of oesophageal dysfunction such a dysphagia, food impaction, and proton pump inhibitor (PPI) resistant dyspepsia. Fibrosis and oesophageal remodelling may occur and lead to oesophageal strictures. An allergic predisposition is common in the EoE population, which appears to be primarily food antigen driven in children and aeroallergen driven in adults. Evidence suggests that the pathogenesis of EoE is due to a dysregulated immunological response to an environmental allergen, resulting in a T helper type 2 (Th2) inflammatory disease and remodelling of the oesophagus in genetically susceptible individuals. Allergen elimination and anti-inflammatory therapy with corticosteroids are currently the mainstay of treatment; however, an increasing number of studies are now focused on targeting different stages in the disease pathogenesis. A greater understanding of the underlying mechanisms resulting in EoE will allow us to improve the therapeutic options available.