The oesophageal string test: a novel, minimally invasive method measures mucosal inflammation in eosinophilic oesophagitis

Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a relatively new disease that has reached an incidence similar to that of Crohn disease and ulcerative colitis. With this increased presence, greater recognition is essential. This applies both to children with nonspecific but potentially debilitating symptoms and to adults who have spent years behaviorally compensating for narrow esophageal strictures. The pathogenesis of EoE is rapidly being unraveled and is based on initiation of a type II allergic response to specific food antigens, leading to dense esophageal eosinophilia, chronic inflammation, and esophageal fibrosis. With greater familiarity and understanding of EoE, treatments are evolving, including identification and avoidance of food antigens; broad applications of topical steroids; and, eventually, pathway-specific biologic therapy.

The Charcot-Leyden crystal protein revisited-A lysopalmitoylphospholipase and more

The Charcot-Leyden crystal protein (CLC-P), a constituent of human and not mouse eosinophils, is one of the most abundant proteins within human eosinophils. It has a propensity to form crystalline structures, Charcot-Leyden crystals, which are hallmarks in their distinctive extracellular crystalline forms as markers of eosinophilic inflammation. The functions of CLC-P within eosinophils have been uncertain. Although the action of CLC-P as a lysophospholipase has been questioned, assays of chromatographically purified CLC-P and crystal-derived CLC-P as well as studies of transfected recombinant CLC-P have consistently documented that CLC-P endogenously expresses lysophospholipase activity, releasing free palmitate from substrate lysopalmitoylphosphatidylcholine. Rather than acting solely as a hydrolytic enzyme to release palmitate from a lysolipid substrate, some other lysophospholipases function more dominantly as acyl-protein thioesterases (APTs), enzymes that catalyze the removal of thioester-linked, long chain fatty acids, such as palmitate, from cysteine residues of proteins. As such APTs participate in palmitoylation, a post-translational modification that can affect membrane localization, vesicular transport, and secretion. CLC-P has attributes of an APT. Thus, whereas CLC-P expresses inherent lysophospholipase activity, like some other lysophospholipase enzymes, it likely also functions in regulating the dynamic palmitoylation cycle, including, given its dominant subplasmalemmal location, at the human eosinophil's plasma membrane.

Galectin-10, the protein that forms Charcot-Leyden crystals, is not stored in granules but resides in the peripheral cytoplasm of human eosinophils

A predominant protein of human eosinophils is galectin-10 (Gal-10), also known as Charcot-Leyden crystal protein (CLC-P) because of its remarkable ability to form Charcot-Leyden crystals (CLCs), which are frequently found in tissues from patients with eosinophilic disorders. CLC-P/Gal-10 is highly expressed in human eosinophils and considered a biomarker of eosinophil involvement in inflammation. However, the intracellular sites where large pools of CLC-P/Gal-10 constitutively reside are still unclear, and whether this protein is derived or not from eosinophil granules remains to be established. Here, we applied pre-embedding immunonanogold transmission electron microscopy combined with strategies for optimal antigen and cell preservation and quantitative imaging analysis to investigate, for the first time, the intracellular localization of CLC-P/Gal-10 at high resolution in resting and activated human eosinophils. We demonstrated that CLC-P/Gal-10 is mostly stored in the peripheral cytoplasm of human eosinophils, being accumulated within an area of ∼250 nm wide underneath the plasma membrane and not within specific (secretory) granules, a pattern also observed by immunofluorescence. High-resolution analysis of single cells revealed that CLC-P/Gal-10 interacts with the plasma membrane with immunoreactive microdomains of high CLC-P/Gal-10 density being found in ∼60% of the membrane area. Eosinophil stimulation with CCL11 or TNF-α, which are known inducers of eosinophil secretion, did not change the peripheral localization of CLC-P/Gal-10 as observed by both immunofluorescence and immuno-EM (electron microscopy). Thus, in contrast to other preformed eosinophil proteins, CLC-P/Gal-10 neither is stored within secretory granules nor exported through classical degranulation mechanisms (piecemeal degranulation and compound exocytosis).

Eosinophilic Gastrointestinal Disorders

Eosinophilic gastrointestinal disorders (EGID) are a group of disorders characterized by pathologic eosinophilic infiltration of the esophagus, stomach, small intestine, or colon leading to organ dysfunction and clinical symptoms (J Pediatr Gastroenterol Nutr; Spergel et al., 52: 300-306, 2011). These disorders include eosinophilic esophagitis (EoE), eosinophilic gastritis (EG), eosinophilic gastroenteritis (EGE), eosinophilic enteritis (EE), and eosinophilic colitis (EC). Symptoms are dependent not only on the location (organ) as well as extent (layer invasion of the bowel wall). Common symptoms of EoE include dysphagia and food impaction in adults and heartburn, abdominal pain, and vomiting in children. Common symptoms of the other EGIDs include abdominal pain, nausea, vomiting, early satiety, diarrhea, and weight loss. These disorders are considered immune-mediated chronic inflammatory disorders with strong links to food allergen triggers. Treatment strategies focus on either medical or dietary therapy. These options include not only controlling symptoms and bowel inflammation but also on identifying potential food triggers. This chapter will focus on the clinical presentation, pathophysiology, and treatment of these increasingly recognized disorders.

Eosinophilic Esophagitis-A Primer for Otolaryngologists

Importance

Eosinophilic esophagitis (EoE) is a chronic, inflammatory condition of the esophagus. Prevalence of EoE is on the rise and, owing to its associated extragastrointestinal manifestations and comorbidities, otolaryngologists are increasingly encountering this condition in their practice.

Observations

Symptoms of EoE are vague and vary greatly based on patient's age. The gastrointestinal symptoms include dysphagia, food impaction, feeding difficulties, symptoms mimicking gastroesophageal reflux, abdominal pain, vomiting, and failure to thrive. Several otolaryngologic symptoms are associated with EoE including rhinosinusitis, chronic cough, recurrent croup, hoarseness, and other aerodigestive symptoms refractory to gastroesophageal reflux therapy. Eosinophilic esophagitis is also frequently associated with other atopic conditions, such as asthma, eczema, and food allergies. The diagnosis is made on endoscopy with biopsies that reveal eosinophil-predominant esophageal inflammation. There are 3 major treatment approaches to EoE, commonly referred to as the 3 Ds: diet, drugs, and dilation. Untreated inflammation of esophagus from EoE can result in irreversible structural damage to the esophagus, leading to fibrosis, strictures, and impaired esophageal function.

Conclusions and Relevance

Eosinophilic esophagitis is now a fairly prevalent condition with considerable morbidity. Otolaryngologists should be familiar with the various clinical presentations of this condition in different age groups. Early diagnosis and treatment of this condition is a key for avoiding or postponing its complications.

Contributions of Eosinophils to Human Health and Disease

The human eosinophil has long been thought to favorably influence innate mucosal immunity but at times has also been incriminated in disease pathophysiology. Research into eosinophil biology has uncovered a number of interesting contributions by eosinophils to health and disease. However, it appears that not all eosinophils from all species are created equal. It remains unclear, for example, exactly how having eosinophils benefits the human host when helminth infections in the developed world have become scarce. This review focuses on our current state of knowledge as it relates to human eosinophils. When information is lacking, we discuss lessons learned from mouse studies that may or may not directly apply to human biology and disease. It is an exciting time to be an "eosinophilosopher" because the use of biologic agents that selectively target eosinophils provides an unprecedented opportunity to define the contribution of this cell to eosinophil-associated human diseases.

Charcot-Leyden crystal protein/galectin-10 interacts with cationic ribonucleases and is required for eosinophil granulogenesis

BACKGROUND

The human eosinophil Charcot-Leyden crystal (CLC) protein is a member of the Galectin superfamily and is also known as galectin-10 (Gal-10). CLC/Gal-10 forms the distinctive hexagonal bipyramidal crystals that are considered hallmarks of eosinophil participation in allergic responses and related inflammatory reactions; however, the glycan-containing ligands of CLC/Gal-10, its cellular function(s), and its role(s) in allergic diseases are unknown.

OBJECTIVE

We sought to determine the binding partners of CLC/Gal-10 and elucidate its role in eosinophil biology.

METHODS

Intracellular binding partners were determined by ligand blotting with CLC/Gal-10, followed by coimmunoprecipitation and coaffinity purifications. The role of CLC/Gal-10 in eosinophil function was determined by using enzyme activity assays, confocal microscopy, and short hairpin RNA knockout of CLC/Gal-10 expression in human CD34⁺ cord blood hematopoietic progenitors differentiated to eosinophils.

RESULTS

CLC/Gal-10 interacts with both human eosinophil granule cationic ribonucleases (RNases), namely, eosinophil-derived neurotoxin (RNS2) and eosinophil cationic protein (RNS3), and with murine eosinophil-associated RNases. The interaction is independent of glycosylation and is not inhibitory toward endoRNase activity. Activation of eosinophils with INF-γ induces the rapid colocalization of CLC/Gal-10 with eosinophil-derived neurotoxin/RNS2 and CD63. Short hairpin RNA knockdown of CLC/Gal-10 in human cord blood-derived CD34⁺ progenitor cells impairs eosinophil granulogenesis.

CONCLUSIONS

CLC/Gal-10 functions as a carrier for the sequestration and vesicular transport of the potent eosinophil granule cationic RNases during both differentiation and degranulation, enabling their intracellular packaging and extracellular functions in allergic inflammation.

Diagnosis and treatment of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an eosinophil-rich, TH2 antigen-mediated disease of increasing pediatric and adult worldwide prevalence. Diagnosis requires greater than or equal to 15 eosinophils per high-power field on light microscopy. Symptoms reflect esophageal dysfunction, and typical endoscopic features include linear furrows, white plaques, and concentric rings. Progressive disease leads to pathologic tissue remodeling, with ensuing esophageal rigidity and loss of luminal diameter caused by strictures. Therapies include proton pump inhibitors, elimination diets, and topical corticosteroids. Effective treatment can reverse tissue fibrosis in some patients, as well as decrease the rate of food impactions. Esophageal dilation might be required to increase luminal patency. The chronic nature of EoE necessitates long-term therapy to avoid disease recurrence and complications. This review serves the function of providing the current state-of-the-art diagnostic criteria and disease management for adult and pediatric EoE.

EoE disease monitoring: Where we are and where we are going

OBJECTIVE

To review literature on various methods of monitoring and characterizing eosinophilic esophagitis (EoE) with respect to their validity as well as risk to the patient.

DATA SOURCES

A literature search was performed using PubMed with keyword combinations of EoE and monitoring as well as various techniques used for monitoring, including but not limited to, symptoms, endoscopy, histology, fluoroscopy, FLIP, noninvasive monitoring, and biomarkers.

STUDY SELECTIONS

Case-control studies, observational studies, peer-reviewed reviews and guidelines, and systematic reviews were selected, reviewed, and summarized here.

RESULTS

A wealth of research regarding monitoring of EoE is currently being undertaken and published. Our review highlights those that have been validated and are currently being used, as well as some that show promise for future monitoring and disease characterization.

CONCLUSION

Eosinophilic esophagitis is a chronic condition that at this time requires upper endoscopy as the gold standard of diagnosis and monitoring. There is a great need in the field for less invasive monitoring tools and better ways to characterize disease to allow for personalization of therapies.

Poor Correlation of Oral Swabs with Esophageal Eosinophil Counts

Eosinophilic esophagitis (EoE) is a chronic condition that requires repeated endoscopies/biopsies to track the disease and treatment response. This invasive procedure involves risk to the patient and has significant costs. We studied whether the detection of specific proteins (cytokines and eosinophil degranulation products) from oral swabs could serve as a minimally invasive test for EoE. Swabs of the oral cavity (buccal and oropharyngeal) were obtained prior to endoscopy/biopsies in patients with EoE, possible EoE, and non-EoE patients in addition to obtaining additional esophageal biopsy tissue. ELISAs measuring the levels of cytokines IL-5, IL-8, IL-13, and eosinophil degranulation products including major basic protein (MBP), eosinophil derived neurotoxin (EDN), and eosinophil peroxidase (EPO) were performed on the samples. Comparisons were made to peak esophageal eosinophil counts. Tolerability of the swabs was evaluated. 43 patients, 4-17 years old, participated in the study. Swabs were well tolerated and all showed measurable protein. 26 patients had EoE [14 active (> 15 eosinophils/high power field), 12 non-active], 17 patients did not have EoE. Results obtained from oral swabs showed poor correlation with those from esophageal tissue. Only measurement of eosinophil degranulation products EDN and EPO from esophageal tissues showed strong correlations with eosinophil counts. In this study, the levels of cytokines and eosinophil degranulation products detected from oral swabs did not correlate with esophageal eosinophilia, and their detection would be insufficient to displace endoscopy/biopsies.

Transnasal Endoscopy in Unsedated Children With Eosinophilic Esophagitis Using Virtual Reality Video Goggles

BACKGROUND & AIMS

Evaluation and treatment of children with eosinophilic esophagitis (EoE) requires serial endoscopic, visual, and histologic assessment by sedated esophagogastroduodenoscopy (EGD). Unsedated transnasal endoscopy (TNE) was reported to be successful in a pilot study of children. We evaluated video goggle and virtual reality-based unsedated TNE in children with EoE, collecting data on rates of completion, adverse events, and adequacy of visual and histologic findings.

METHODS

We performed a retrospective study of 190 children and young adults (age, 3-22 y) who underwent video goggle or virtual reality-based unsedated TNE from January 2015 through February 2018. We analyzed data on patient demographics, procedure completion, endoscope type, adverse events, visual and histologic findings, estimated costs, and duration in the facility. Esophageal biopsies from the first 173 subjects who underwent TNE were compared with those from previous EGD evaluations.

RESULTS

During 300 attempts, 294 TNEs were performed (98% rate of success). Fifty-four patients (age, 6-18 y) underwent multiple TNEs for dietary or medical management of EoE. There were no significant adverse events. Visual and histologic findings were adequate for assessment of EoE. TNE reduced costs by 53.4% compared with EGD (TNE $4393.00 vs EGD $9444.33). TNE was used increasingly from 2015 through 2017, comprising 31.8% of endoscopies performed for EoE. The total time spent in the clinic (front desk check-in to check-out) in 2018 was 71 minutes.

CONCLUSIONS

In a retrospective study of 190 children and young adults (age, 3-22 y) who underwent video goggle or virtual reality-based unsedated TNE, TNE was safe and effective and reduced costs of EoE monitoring. Advantages of TNE include reduced risk and cost associated with anesthesia as well as decreased in-office time, which is of particular relevance for patients with EoE, who require serial EGDs.

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

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

Eosinophilic gastrointestinal diseases - Pathogenesis, diagnosis, and treatment

Eosinophilic gastrointestinal diseases (EGIDs) are divided into eosinophilic esophagitis (EoE) and eosinophilic gastroenteritis (EGE), depending on the involved gastrointestinal tract, though both are considered to be chronic Th2-type allergic diseases caused by food or environmental allergens. In development of EoE, refluxed gastric acid may also have an important role. For diagnosis of EGIDs, the presence of symptoms possibly originating from the involved gastrointestinal tract and dense eosinophil infiltration are important factors. Imaging studies, including endoscopy and computed tomography, along with histopathological examinations of biopsy specimens are useful for diagnosis, whereas laboratory testing of blood, urine, and stool samples has limited value. Three useful options for treating EoE patients are acid inhibitors, swallowed topical corticosteroids, and an elimination diet, while systemic administration of glucocorticoids is the standard treatment of EGE, though information is limited. Since the prevalence of EGIDs is increasing in Western countries as well as Japan, development of effective treatments based on sufficient evidence is becoming an urgent need.

One-Hour Esophageal String Test: A Nonendoscopic Minimally Invasive Test That Accurately Detects Disease Activity in Eosinophilic Esophagitis

OBJECTIVES

Eosinophilic esophagitis (EoE), a chronic food allergic disease, lacks sensitive and specific peripheral biomarkers. We hypothesized that levels of EoE-related biomarkers captured using a 1-hour minimally invasive Esophageal String Test (EST) would correlate with mucosal eosinophil counts and tissue concentrations of these same biomarkers. We aimed to determine whether a 1-hour EST accurately distinguishes active from inactive EoE or a normal esophagus.

METHODS

In a prospective, multisite study, children and adults (ages 7-55 years) undergoing a clinically indicated esophagogastroduodenoscopy performed an EST with an esophageal dwell time of 1 hour. Subjects were divided into 3 groups: active EoE, inactive EoE, and normal esophageal mucosa. Eosinophil-associated protein levels were compared between EST effluents and esophageal biopsy extracts. Statistical modeling was performed to select biomarkers that best correlated with and predicted eosinophilic inflammation.

RESULTS

One hundred thirty-four subjects (74 children, 60 adults) with active EoE (n = 62), inactive EoE (n = 37), and patient controls with a normal esophagus (n = 35) completed the study. EST-captured eosinophil-associated biomarkers correlated significantly with peak eosinophils/high-power field, endoscopic visual scoring, and the same proteins extracted from mucosal biopsies. Statistical modeling, using combined eotaxin-3 and major basic protein-1 concentrations, led to the development of EoE scores that distinguished subjects with active EoE from inactive EoE or normal esophagi. Eighty-seven percent of children, 95% of parents, and 92% of adults preferred the EST over endoscopy if it provided similar information.

DISCUSSION

The 1-hour EST accurately distinguishes active from inactive EoE in children and adults and may facilitate monitoring of disease activity in a safe and minimally invasive fashion.

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.

New developments in diagnosis and treatment of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic, allergen-driven, immune mediated disease of the esophagus that progresses to esophageal fibrostenosis if not well treated. The aim of this review is to provide an update on recent clinical advances in the development of diagnostic and therapeutic approaches for EoE. At present, the diagnosis and disease monitoring for EoE rely on repetitive endoscopic evaluations and esophageal tissue acquisition for histopathologic analysis. Recent advancements in EoE diagnosis include transnasal endoscopy, endoscopic functional lumen imaging probe, 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. The current treatment modalities for EoE are topical corticosteroid, proton-pump inhibitors, elimination diet, and dilation. 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. Especially, dupilumab is promising to become the orphan drug of EoE.

Eosinophilic esophagitis in children: current knowledge to open new horizons

Eosinophilic Esophagitis (EoE) is a chronic immune/antigen-mediated condition which is also driven by genetic and environmental factors. It has been deeply investigated over the last years and its incidence is widely increasing in childhood. Although atopic diseases are closely linked with EoE, it does not recognize a classical IgE-mediate immune pathogenesis but it is rather a T helper type 2 inflammatory process. Familial clustering supports genetic predisposition in EoE and recent advances in understanding the genetic basis for EoE may eventually translate into targeted management of the disease. EoE diagnosis is based on clinical symptoms, micro, and macroscopic findings along with exclusion of gastroesophageal reflux disease (GERD) evidence. Management of the disease encompasses both dietary and pharmacological solutions that need to be specifically targeted on patients' history, clinical symptoms, and diagnostic evaluations. New therapies, currently not available in children, may represent the basis for future therapeutic options in the next years.

Charcot-Leyden Crystals in Eosinophilic Inflammation: Active Cytolysis Leads to Crystal Formation

PURPOSE OF REVIEW

Charcot-Leyden crystals (CLCs), slender bipyramidal hexagonal crystals, were first described by Jean-Martin Charcot in 1853, predating Paul Ehrlich's "discovery" of eosinophils by 26 years. To date, CLCs are known as a classical hallmark of eosinophilic inflammation. CLC protein expresses palmitate cleaving lysophospholipase activity and is a member of the family of S-type lectins, galectin-10. We summarize current knowledge regarding the pathological observations of CLCs and their mechanism of generation focusing on eosinophil cell death.

RECENT FINDINGS

The presence of CLCs in vivo has been consistently associated with lytic eosinophils. Recent evidence revealed that cytolysis represents the occurrence of extracellular trap cell death (ETosis), an active non-apoptotic cell death process releasing filamentous chromatin structure. Galectin-10 is a predominant protein present within the cytoplasm of eosinophils but not stored in secretory granules. Activated eosinophils undergo ETosis and loss of galectin-10 cytoplasmic localization results in intracellular CLC formation. Free galectin-10 released following plasma membrane disintegration forms extracellular CLCs. Of interest, galectin-10-containing extracellular vesicles are also released during ETosis. Mice models indicated that CLCs could be a novel therapeutic target for Th2-type airway inflammation. The concept of ETosis, which represents a major fate of activated eosinophils, expands our current understanding by which cytoplasmic galectin-10 is crystalized/externalized. Besides CLCs and free galectin-10, cell-free granules, extracellular chromatin traps, extracellular vesicles, and other alarmins, all released through the process of ETosis, have novel implications in various eosinophilic disorders.

Charcot-Leyden crystal protein/galectin-10 is a surrogate biomarker of eosinophilic airway inflammation in asthma

Aim: Eosinophilic asthma is associated with more exacerbations and differential responses to treatment. The aim of this study was to assess if CLC/Gal-10 and MBP-1 are surrogate biomarkers of eosinophilic inflammation in asthma. Methods & results: Sputum induction was performed in patients with asthma and in healthy controls. Sputum analysis revealed higher (p < 0.001) levels of CLC/Gal-10 and MBP-1 in asthmatics versus healthy controls. CLC/Gal-10 levels were highly correlated (rs = 0.74; p < 0.001) with sputum eosinophils; MBP-1 approached significance (r = 0.44; p = 0.07). Conclusion: Increased CLC/Gal-10 and MBP-1 levels in the sputum were strongly correlated with sputum eosinophils in patients with asthma. CLC/Gal-10 and MBP-1 may be useful biomarkers for differentiation of eosinophilic airway inflammation in asthma.

The Microbiome and Food Allergy

The gut-associated lymphoid tissue (GALT) faces a considerable challenge. It encounters antigens derived from an estimated 1014 commensal microbes and greater than 30 kg of food proteins yearly. It must distinguish these harmless antigens from potential pathogens and mount the appropriate host immune response. Local and systemic hyporesponsiveness to dietary antigens, classically referred to as oral tolerance, comprises a distinct complement of adaptive cellular and humoral immune responses. It is increasingly evident that a functional epithelial barrier engaged in intimate interplay with innate immune cells and the resident microbiota is critical to establishing and maintaining oral tolerance. Moreover, innate immune cells serve as a bridge between the microbiota, epithelium, and the adaptive immune system, parlaying tonic microbial stimulation into signals critical for mucosal homeostasis. Dysregulation of gut homeostasis and the subsequent disruption of tolerance therefore have clinically significant consequences for the development of food allergy.

Cost-effective care in eosinophilic esophagitis

OBJECTIVE

To examine costs related to eosinophilic esophagitis (EoE), understand the source of these costs, discuss a possible approach for cost-effective care in EoE, and identify areas for future research in this topic.

DATA SOURCES/STUDY SELECTIONS

Narrative review of the literature from 1977 (first description of EoE) to March 2019, focusing on costs and cost-effectiveness analyses in EoE.

RESULTS

High costs in EoE can be related to diagnostic delays, requirement for upper endoscopy with biopsy for diagnosis and monitoring of disease activity, expensive medications currently used off-label, increased food costs related to dietary elimination treatment, frequent doctor visits with subspecialists, and complications or disease exacerbations. Provision of cost-effective care in EoE is an understudied area, and a patient-centric approach is key. There are multiple areas in which future research can make an impact. These include determining predictors of treatment response, minimally or noninvasive methods to monitor disease activity, and validation of the use of multidisciplinary care.

CONCLUSION

Eosinophilic esophagitis (EoE) is considered to be a rare disease, but the costs of care and burden of disease attributed to EoE are substantial. However, few studies examine either the costs related to EoE or the approach to cost-effective care for the EoE patient. To provide cost-effective care, a patient-centric approach and shared decision-making model are optimal. In addition, a rational strategy for EoE diagnosis and initial treatment, effective maintenance therapy for disease control and ideally to prevent complications, and appropriate long-term monitoring are all required.

Serum eosinophilic cationic protein is correlated with food impaction and endoscopic severity in eosinophilic esophagitis

BACKGROUND/AIMS

The aim of the present study was to analyze the diagnostic accuracy of serum eosinophilic cationic protein (ECP) for eosinophilic esophagitis (EoE) and the correlation of ECP with clinical, histopathological, laboratory, and endoscopic features of EoE.

MATERIALS AND METHODS

Fifteen patients with EoE and 14 healthy controls were included in the study. Demographic parameters were recorded. EoE Endoscopic Reference Score (EREFS) was calculated according to endoscopic features, and esophageal biopsies were obtained by a single experienced endoscopist in a patient group. Serum ECP levels (μg/mL), absolute eosinophil count (U/mm3), and maximum peak of eosinophils/high-power field in esophageal biopsies were analyzed.

RESULTS

The median age of all participants was 33.0 (min-max: 18-46) years. There were 27 (93.1%) male patients. Serum ECP level was significantly higher in patients with EoE than in healthy volunteers (20.4 vs. 8.8, p<0.0001). According to the receiver operating characteristic (ROC) curve analysis, ECP had 80% sensitivity and 92.8% specificity to diagnose EoE with a cut-off value of 13.9 µg/mL (area under the ROC curve 0.895; p<0.0001; 95% CI: 0.725-0.978). EREFS (p<0.0001) and the presence of food impaction (p=0.04) were significantly correlated with ECP.

CONCLUSION

Serum ECP is an accurate non-invasive biomarker for EoE with high specificity and sensitivity. In addition, ECP is strongly correlated with EREFS and the symptom of food impaction.

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.

Maintenance Treatment Of Eosinophilic Esophagitis With Swallowed Topical Steroids Alters Disease Course Over A 5-Year Follow-up Period In Adult Patients

BACKGROUND & AIMS

Although swallowed topical corticosteroids (STCs) are effective in inducing remission of active eosinophilic esophagitis (EoE), there are few data on maintenance of long-term remission. We evaluated the long-term effectiveness of STC therapy for adults with EoE.

METHODS

We performed a retrospective study using the Swiss EoE database. We analyzed data on 229 patients with EoE treated with STCs (175 male; mean age at diagnosis, 39±15 years; median time until diagnosis, 6 years) from 2000 through 2014. Patients were followed for a median of 5 years (interquartile range [IQR], 3-7 years). We collected data from 819 follow-up visits on clinical, endoscopic and histological disease characteristics. The primary endpoint was proportions of clinical, endoscopic, and histological remission in all patients and groups, based on the status and duration of STC treatment.

RESULTS

Patients were taking STCs at 336 of the follow-up visits (41.0% of visits). The median duration of STC use before a follow-up visit was 347 days (IQR, 90-750 days) corresponding to 677 doses (IQR, 280-1413 doses) of 0.25 mg each. At the visits, higher proportions of patients who were still taking STCs were in clinical remission (31.0%) compared to patients not taking STCs (4.5%) (P <.001), as well as endoscopic remission (48.8% vs 17.8%; P < .001), histologic remission (44.8% vs 10.1%; P < .001), and complete remission (16.1% vs 1.3%; P < .001). Higher cumulative doses of STCs and longer durations of treatment were associated with higher proportions of clinical and complete remission. No dysplasia or mucosal atrophy was detected. Esophageal candidiasis was observed at 2.7% of visits in patients taking STCs.

CONCLUSION

In an analysis of data from the Swiss EoE database, we found maintenance therapy with STCs to achieve complete remission at 16.1% of follow-up visits, which was higher than in patients receiving no treatment (1.3%). Given the good safety profile of low-dose STC, we advocate for a prolonged treatment. Dose-finding trials are needed to achieve higher remission rates.

[Eosinophilic granulocytes-Physiology and pathophysiology]

Eosinophilic granulocytes are a subpopulation of leucocytes and part of the innate immune cell pool. Additionally, they have homeostatic functions in different tissues. Classically, an increased number of eosinophils is associated with allergies and parasitic infections; however, eosinophilia can also be found in vasculitides and malignant tumors. The most important controlling factors of eosinophils are the cytokine interleukin 5 and eotaxins. Eosinophils are able to produce a broad range of signalling factors and toxic proteins, which are stored in cytoplasmic granules and can be quickly and specifically released when needed depending on the stimulus. To combat pathogens, eosinophils can catapult extracellular traps consisting of mitochondrial DNA and toxic proteins into the intercellular space. This review focuses on the basic structure, control and function of eosinophils in health and disease.

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.

Serum Levels of Eosinophil-Derived Neurotoxin: A Biomarker for Asthma Severity in Adult Asthmatics

Purpose

Eosinophilic inflammation is a key component of severe asthma (SA). However, there has been no reliable serum biomarker for the eosinophilic inflammation of SA. We hypothesized that serum eosinophil-derived neurotoxin (EDN) could predict the eosinophilic inflammation of SA in adult asthmatics.

Methods

Severe asthmatics (n = 235), nonsevere asthmatics (n = 898), and healthy controls (n = 125) were enrolled from Ajou University Hospital, South Korea. The serum levels of EDN and periostin were measured by enzyme-linked immunosorbent assay and compared between severe and nonsevere asthmatics. Their associations with total eosinophil count (TEC) and clinical parameters were evaluated; clinical validation of the K-EDN kit for the measurement of serum EDN was evaluated.

Results

Severe asthmatics were older and had longer disease duration with significantly lower levels of forced expiratory volume in 1 second and methacholine PC20 than nonsevere asthmatics. Significant differences were found in TEC or sputum eosinophil count (%) between the groups. The serum levels of EDN and periostin were significantly higher in severe asthmatics than in nonsevere asthmatics and in healthy controls (all P < 0.05). Although significant correlations were found between serum EDN levels measured by the 2 kits (ρ = 0.545, P < 0.0001), higher correlation coefficients between serum EDN levels measured by the K-EDN kit and TEC were higher (ρ = 0.358, P < 0.0001) than those between serum EDN levels measured by the MBL kit and TEC (ρ = 0.319, P < 0.0001) or serum periostin level (ρ = 0.222, P < 0.0001). Multivariate regression analysis demonstrated that serum EDN levels measured by the K-EDN kit predicted the phenotype of SA (P = 0.003), while 2 other biomarkers did not.

Conclusions

The serum EDN level may be a useful biomarker for assessing asthma severity in adult asthmatics.

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.

Clinical Presentation and Approach to Dietary Management of Eosinophilic Esophagitis

Eosinophilic gastrointestinal disorders are a group of disorders that are characterized by chronic eosinophilic inflammation in the gastrointestinal tract, leading to organ dysfunction and clinical symptoms. The disorders are considered immune-mediated and inflammatory, with strong associations to food allergy triggers. The most common eosinophilic gastrointestinal disorder is eosinophilic esophagitis (EoE), which usually presents with dysphagia and food impaction in adults and with heartburn, abdominal pain, and vomiting in children. Treatment strategies consist of medical and dietary therapies. In addition to the clinical presentation of EoE, this article focuses on dietary management, which includes controlling symptoms and bowel inflammation as well as identifying potential food triggers to help tailor a diet for long-term disease management.

Blind esophageal brushing offers a safe and accurate method to monitor inflammation in children and young adults with eosinophilic esophagitis

Patients with eosinophilic esophagitis (EoE) require frequent evaluation of mucosal inflammation via endoscopy. Instead of endoscopy, mucosal evaluation in adults with esophageal cancer and candidiasis is achieved using a cytology brush inserted through a nasogastric tube (NGT). We conducted a prospective cross-sectional study in children and young adults scheduled for routine esophagogastroduodenoscopy (EGD) where in Phase 1, we performed esophageal brushing through the endoscope under direct visualization and in Phase 2, we inserted the brush through a Cortrak® NGT prior to endoscopy. Eosinophil-derived neurotoxin (EDN) measured by ELISA in the samples extracted from brushes was validated as the sensitive biomarker. We collected 209 esophageal brushing samples from 94 patients and we found that EDN in brushing samples collected via EGD or NGT was significantly higher in patients having active EoE (n = 81, mean EDN 381 mcg/mL) compared with patients having gastroesophageal reflux disease (n = 31, mean EDN 1.9 mcg/mL, P = 0.003), EoE in remission (n = 47, mean EDN 3.7 mcg/mL, P = 0.003), or no disease (n = 50, mean EDN 1.1 mcg/mL, P = 0.003). EDN at a concentration of ≥10 mcg/mL of brushing sample was found to accurately detect active EoE. NGT brushing did not cause any significant adverse effects. We concluded that blind esophageal brushing using an NGT is a fast, less invasive, safe, and well-tolerated technique compared with EGD to detect and monitor EoE inflammation using EDN as the sensitive biomarker.

Charcot-Leyden crystal formation is closely associated with eosinophil extracellular trap cell death

Protein crystallization in human tissue rarely occurs. Charcot-Leyden crystals (CLCs) were described in various eosinophilic diseases >150 years ago, but our understanding of CLC formation still remains limited. In this study, we demonstrate that CLCs observed in varied inflamed human tissues are closely associated with eosinophil cell-free granules and nuclear envelope/plasma membrane disintegration with release of filamentous chromatin (extracellular traps), typical morphologies of a regulated pathway of extracellular trap cell death (ETosis). During the process of eosinophil ETosis, eccentrically localized cytoplasmic and perinuclear CLC protein (galectin-10) is homogeneously redistributed in the cytoplasm. Rapid (1-2 minutes) formation of intracytoplasmic CLCs was observed using time-lapse imaging. Plasma membrane rupture enabled the release of both intracellularly formed CLCs and soluble galectin-10 that further contributed to formation of CLCs extracellularly, in parallel with the expulsion of free intact granules and extracellular traps. CLC formation and galectin-10 release were dependent on nicotinamide adenine dinucleotide phosphate oxidase activation. To our knowledge, this is the first demonstration of natural formation of CLCs in association with an active physiological process (ie, ETosis). These results indicate that dynamic changes in intracellular localization and release of galectin-10 contribute to CLC formation in vivo and suggest that CLC/galectin-10 might serve as an indicator of ETosis.

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: 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.

Eosinophilic esophagitis: short and long-term considerations

PURPOSE OF REVIEW

Eosinophilic esophagitis (EoE) is a relatively new disease but its understanding is evolving over a period of time. This review highlights recent advances in the understanding of pathophysiology, diagnostic modalities, short and long-term goals of therapy and novel therapeutic agents.

RECENT FINDINGS

The prevalence of EoE is increasing. Upper endoscopy and biopsy remains the gold standard for diagnosing EoE but less invasive and more cost-effective testing has been under investigation. Scoring systems to assess symptoms, histology and endoscopic findings can distinguish between active and inactive disease. Step up therapy with 2-4-6 food elimination can result in early identification of triggering foods and reduce frequency of endoscopies. The term proton pump inhibitor (PPI) responsive eosinophilia should be avoided and PPI should be considered a therapeutic modality. Oral viscous budesonide has been more effective than fluticasone in achieving remission. Adrenal suppression should be looked for patients on swallowed steroids. IL-13 antagonists can be a promising therapy for EoE and dilation is a safe and effective treatment modality in patients with EoE but as is expected, does not decrease inflammation.

SUMMARY

EoE has been increasingly recognized as a cause of food impactions and dysphagia. Less invasive methods for diagnosis and to monitor treatment response have been studied but need validation in children. Short-term treatment goals include symptomatic and histological improvement, with prevention of fibrostenotic disease the primary long-term goal. Elemental diet and empiric elimination diet appear to be successful in inducing remission. PPI and swallowed steroids cause symptomatic improvement and histological remission but relapse is common after discontinuation of therapy.

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.

Revisiting the NIH Taskforce on the Research needs of Eosinophil-Associated Diseases (RE-TREAD)

Eosinophil-associated diseases (EADs) are rare, heterogeneous disorders characterized by the presence of eosinophils in tissues and/or peripheral blood resulting in immunopathology. The heterogeneity of tissue involvement, lack of sufficient animal models, technical challenges in working with eosinophils, and lack of standardized histopathologic approaches have hampered progress in basic research. Additionally, clinical trials and drug development for rare EADs are limited by the lack of primary and surrogate endpoints, biomarkers, and validated patient-reported outcomes. Researchers with expertise in eosinophil biology and eosinophil-related diseases reviewed the state of current eosinophil research, resources, progress, and unmet needs in the field since the 2012 meeting of the NIH Taskforce on the Research of Eosinophil-Associated Diseases (TREAD). RE-TREAD focused on gaps in basic science, translational, and clinical research on eosinophils and eosinophil-related pathogenesis. Improved recapitulation of human eosinophil biology and pathogenesis in murine models was felt to be of importance. Characterization of eosinophil phenotypes, the role of eosinophil subsets in tissues, identification of biomarkers of eosinophil activation and tissue load, and a better understanding of the role of eosinophils in human disease were prioritized. Finally, an unmet need for tools for use in clinical trials was emphasized. Histopathologic scoring, patient- and clinician-reported outcomes, and appropriate coding were deemed of paramount importance for research collaborations, drug development, and approval by regulatory agencies. Further exploration of the eosinophil genome, epigenome, and proteome was also encouraged. Although progress has been made since 2012, unmet needs in eosinophil research remain a priority.

An Evolving Approach to the Diagnosis of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergic/ immune-mediated esophageal disease. Knowledge related to the clinical presentation, pathogenesis, epidemiology, natural history, treatment, and outcomes of EoE has rapidly evolved over the past 2 decades. This article focuses on the similarly evolving diagnostic framework for EoE. In the initial clinical guidelines, diagnosis of EoE was based on symptoms of esophageal dysfunction; at least 15 eosinophils per high-power field (eos/hpf) on esophageal biopsy; and either a lack of response to high-dose proton pump inhibitor (PPI) therapy, or normal pH monitoring. The first 2 criteria have remained largely unchanged; however, the role of PPIs has been controversial, particularly due to the recognition of PPI-responsive esophageal eosinophilia (PPI-REE), in which patients with suspected EoE experience resolution of symptoms and esophageal eosinophilia with PPI therapy. A quickly expanding evidence base has found that most adult patients with EoE and PPI-REE share similar clinical, endoscopic, histologic, immunologic, and molecular characteristics prior to the use of PPIs. Because of this, the most recent diagnostic guidelines have removed the lack of response to PPIs as a diagnostic criterion; PPIs are now better considered as a treatment for esophageal eosinophilia. EoE should currently be suspected on a clinical basis when there are symptoms of esophageal dysfunction and at least 15 eos/hpf on esophageal biopsies. A history of atopy and endoscopic signs of EoE are strongly supportive of the diagnosis. However, the diagnosis cannot be confirmed until a thorough evaluation of other potential causes of esophageal eosinophilia has been performed.

New Developments in the Diagnosis, Therapy, and Monitoring of Eosinophilic Esophagitis

PURPOSE OF REVIEW

Eosinophilic esophagitis (EoE) has transformed over the past two decades from a little-known entity to a significant cause of morbidity in the adult and pediatric population. We reviewed the most recent advancements in the diagnosis, therapy, and long-term monitoring of EoE.

RECENT FINDINGS

Based on clinical, endoscopic, histologic, immunologic, and genetic similarities, there is growing consensus to move away from distinguishing proton pump inhibitor responsive esophageal eosinophilia as an entity distinct from EoE. An increasing number of studies have identified duration of untreated disease as an important determinant of esophageal stricture formation. New approaches to the empiric elimination diet including one, two, four, and step-up protocols were developed to reduce the need for repeated endoscopies during reintroduction of food triggers. Topical steroids remain the mainstay of medical therapy but newer formulations are under development to optimize esophageal delivery. Novel, disease activity monitoring techniques are being evaluated that assess esophageal inflammatory activity without the need for endoscopy. Understanding of EoE has increased remarkably from the first identification of the disease. The underlying pathogenesis continues to be explored leading to shifts in diagnostic criteria as well as novel therapeutic targets. Innovative methods to monitor disease are under investigation and more research is needed to understand the natural history of EoE.

Clinical Translation of Tethered Confocal Microscopy Capsule for Unsedated Diagnosis of Eosinophilic Esophagitis

Esophagogastroduodenoscopy (EGD) is a widely used procedure, posing significant financial burden on both healthcare systems and patients. Moreover, EGD is time consuming, sometimes difficult to tolerate, and suffers from an imperfect diagnostic yield as the limited number of collected biopsies does not represent the whole organ. In this paper, we report on technological and clinical feasibility of a swallowable tethered endomicroscopy capsule, which is administered without sedation, to image large regions of esophageal and gastric mucosa at the cellular level. To demonstrate imaging capabilities, we conducted a human pilot study (n = 17) on Eosinophilic Esophagitis (EoE) patients and healthy volunteers from which representative cases are presented and discussed. Results indicate that, compared to endoscopic biopsy, unsedated tethered capsule endomicroscopy obtains orders of magnitude more cellular information while successfully resolving characteristic tissue microscopic features such as stratified squamous epithelium, lamina propria papillae, intraepithelial eosinophils, and gastric cardia and body/fundic mucosa epithelia. Based on the major import of whole organ, cellular-level microscopy to obviate sampling error and the clear cost and convenience advantages of unsedated procedure, we believe that this tool has the potential to become a simpler and more effective device for diagnosing and monitoring the therapeutic response of EoE and other esophageal diseases.

The role of maintenance therapy in eosinophilic esophagitis: who, why, and how?

In patients with eosinophilic esophagitis (EoE) who do not respond to proton pump inhibitors, initial anti-inflammatory/anti-eosinophilic treatment is with either topical corticosteroids or dietary elimination. A large body of literature supports the efficacy of these approaches, with histologic response rates in the 50-90% range for steroids and 70% range for the six-food elimination diet. However, these studies are almost all short-term and data evaluating long-term safety and efficacy of either treatment are limited. Nevertheless, because EoE is chronic, symptomatic, endoscopic, and histologic disease activity recurs when successful treatments are stopped. An emerging body of data also suggest that left untreated, persistent eosinophilic esophageal inflammation may progress to fibrostenosis over time. Therefore, maintenance therapy in EoE is intuitively attractive. This paper reviews the rationale for maintenance treatment in EoE, the available long-term pharmacologic and dietary response data for EoE, and discusses who may benefit the most from ongoing treatment. While all patients with EoE can be offered maintenance treatment, this option should be strongly recommended in patients with severe disease phenotypes or complications, including malnutrition or failure to thrive, esophageal fibrostenosis, strictures requiring dilation, recurrent food bolus impaction, history of perforation, and symptoms that recur quickly after treatment discontinuation. In all EoE patients, regular follow-up is also advised.