A critical role for eotaxin in experimental oral antigen-induced eosinophilic gastrointestinal allergy

Balancing immune responses: regulatory cells in eosinophilic gastrointestinal disorders

Eosinophilic gastrointestinal disorders (EGIDs) are a group of conditions characterized by an abnormal accumulation of eosinophils in the gastrointestinal tract, leading to inflammation and tissue damage. Regulatory cells are a subset of immune cells that are crucial in maintaining the balance of the immune system and preventing the occurrence of autoimmune diseases. In EGIDs, regulatory cells are believed to play a key role in controlling the immune response and overseeing the growth and activation of eosinophils in the gastrointestinal tract. There is evidence indicating that regulatory T cells (Tregs) and regulatory eosinophils may play a role in suppressing the inflammatory response in EGIDs. Regulatory eosinophils are a subgroup of eosinophils that possess an anti-inflammatory role. Recent studies have shown that enhancing the number or effectiveness of regulatory eosinophils can reduce the severity of EGIDs. Regulatory eosinophils dampen inflammation through their regulatory mediators, such as galectin-10 and growth factor beta (TGF-β), which promote Treg expansion and inhibit effector T cell function. Further research on regulatory cells in EGIDs may have significant implications for the advancement of novel therapies for these uncommon and intricate disorders. The aim of this review is to provide complete view of the immune responses connected to EGIDs, examine the regulatory cells that control these responses, and evaluate their potential as therapeutic targets for EGID treatment.

Eosinophilic enteritis in a case of cystic fibrosis: an elusive diagnosis with an elementary cure

A late adolescent man diagnosed with cystic fibrosis and presenting with predominantly gastrointestinal symptoms, including chronic constipation, exocrine pancreatic insufficiency and gastro-oesophageal reflux disease, experienced recurrent episodes of nausea, vomiting and abdominal pain. CT of the abdomen unveiled the presence of chronic appendicitis, alongside constipation without evidence of distal intestinal obstruction syndrome. Endoscopic biopsies revealed small bowel eosinophilic infiltrates. Subsequently, the patient underwent an appendectomy, and a tailored regimen was established to address constipation, resulting in an initial alleviation of his symptoms. Three months later, a resurgence of symptoms occurred, coinciding with persistent intestinal eosinophilic infiltrates. A diagnosis of eosinophilic enteritis was rendered, and treatment commenced with an oral dosage of 40 mg of prednisone. Two weeks later, the patient experienced symptom resolution, corroborated by the findings of an endoscopic biopsy conducted 8 weeks later. During a follow-up examination 6 months later, the patient remained asymptomatic.

Hospitalization Trends and Outcomes of Eosinophilic Esophagitis in the United States: A Decade-Long Nationwide Analysis

Background Eosinophilic esophagitis (EoE) is a chronic antigen-mediated esophageal disease characterized by infiltration of the esophageal mucosa by eosinophils. The prevalence of EoE continues to rise worldwide. However, certain aspects of the epidemiology and pathogenesis remain unclear. Methods This study examined the hospitalization trends of EoE using an extensive inpatient database in the United States, the National (Nationwide) Inpatient Sample (NIS), to identify hospitalizations between 2010 and 2019. We assessed patient demographics as well as hospital-specific variables using the NIS. We obtained the prevalence rate of EoE for each year and used joinpoint regression analysis to obtain trends after adjusting the rate for age and gender. We also sought to characterize the outcomes of these hospitalizations by obtaining the mortality rate, length of stay (LOS), and total hospital charges (THC). Results Of 305 million hospitalizations included in the study, 33,878 were for EoE. The prevalence rate per 100,000 hospitalizations of EoE increased from 6.6 in 2010 to 15.5 in 2019. The annual percentage change obtained from the joinpoint regression analysis was 13.3% from 2010 to 2014 and 7.2% from 2014 to 2019. Most of the hospitalizations were among the male gender and young adults. Almost 95% of hospitalizations across the study period were seen in urban hospitals. We did not notice any significant trend in the mortality rates or length of stay over the study period. The THC increased significantly across the study period. Conclusion There has been an upward trend in the average prevalence rate of EoE over the decade from 2010 to 2019 which almost parallels that of inflammatory bowel disease. This represents a significant burden of disease for a condition that was initially recognized in the late 20th century.

CD193 ( CCR3 ) expression by B cells correlates with reduced IgE production in paediatric schistosomiasis

We demonstrate that CD193, the eotaxin receptor, is highly expressed on circulating B cells in paediatric schistosomiasis mansoni. CD193 plays a role in directing granulocytes into sites of allergic-like inflammation in the mucosa, but little is known about its functional significance on human B cells. We sought to characterize CD193 expression and its relationship with S. mansoni infection. We found that CD193+ B cells increased with the intensity of schistosome infection. In addition, a significant negative association was observed between CD193 expression by B cells and IgE production. Decreased IgE levels are generally associated with susceptibility to re-infection. B cell stimulation with eotaxin-1 increased CD193 levels whereas IL-4 led to a reduction. This was supported by plasma levels of eotaxin-1 correlating with CD193 levels on B cells and other cells. In contrast, CD193 expression was induced on naive B cells with a combination of IL-10 and schistosome antigens. Whereas T cells had a modest increase in CD193 expression, only B cell CD193 appeared functionally chemotactic to eotaxin-1. Thus, CD193+ B cells, which co-express CXCR5, may be enroute to sites with allergic-like inflammation, such as gastrointestinal follicles, or even to Th2 granulomas, which develop around parasite eggs. Overall, our results suggest that schistosome infection may promote CD193 expression and suppress IgE via IL-10 and other undefined mechanisms related to B cell trafficking. This study adds to our understanding of why young children may have poor immunity. Nonetheless, praziquantel treatment was shown to reduce percentages of circulating CD193+ B cells lending hope for future vaccine efforts.

Eosinophilic esophagitis: Immune mechanisms and therapeutic targets

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

Eosinophilic Gastrointestinal Diseases Beyond the Esophagus: An Evolving Field and Nomenclature

The eosinophilic gastrointestinal diseases (EGIDs) are a group of chronic, immune-mediated gastrointestinal (GI) diseases characterized by GI symptoms and pathologic eosinophilic infiltration of specific areas within the GI tract in the absence of secondary causes of eosinophilia. The non-eosinophilic esophagitis EGIDs remain understudied and likely underdiagnosed, owing in part to the lack of clarity in the terminology previously used to describe these diseases. The newly established EGID nomenclature framework includes a first-tier description of the specific location of GI tract involvement and a second-tier description with more granular characterizations of disease involvement. EGIDs can involve any segment or layer of the GI tract, so patients can present with a wide array of common, nonspecific GI symptoms. Diagnosing EGIDs requires endoscopic evaluation and biopsies showing increased eosinophilic tissue infiltration in the correct clinical context after ruling out other causes of eosinophilia. Although the pathogenesis is not yet fully understood, EGIDs are likely allergic conditions triggered by food antigen exposure. Most patients are currently treated with corticosteroids, but investigations of other pharmacologic and dietary therapies are ongoing. This article highlights the recently updated EGID nomenclature and summarizes the current understanding of the diagnosis, pathogenesis, and treatment of EGIDs.

Evaluating Eosinophilic Colitis as a Unique Disease Using Colonic Molecular Profiles: A Multi-Site Study

BACKGROUND & AIMS

Colonic eosinophilia, an enigmatic finding often referred to as eosinophilic colitis (EoC), is a poorly understood condition. Whether EoC is a distinct disease or a colonic manifestation of eosinophilic gastrointestinal diseases (EGIDs) or inflammatory bowel disease (IBD) is undetermined.

METHODS

Subjects with EoC (n = 27) and controls (normal [NL, n = 20], Crohn's disease [CD, n = 14]) were enrolled across sites associated with the Consortium of Eosinophilic Gastrointestinal Disease Researchers. EoC was diagnosed as colonic eosinophilia (ascending ≥100, descending ≥85, sigmoid ≥65 eosinophils/high-power field) with related symptoms. Colon biopsies were subjected to RNA sequencing. Associations between gene expression and histologic features were analyzed with Spearman correlation; operational pathways and cellular constituents were computationally derived.

RESULTS

We identified 987 differentially expressed genes (EoC transcriptome) between EoC and NL (>1.5-fold change, P < .05). Colonic eosinophil count correlated with 31% of EoC transcriptome, most notably with CCL11 and CLC (r = 0.78 and 0.77, P < .0001). Among EoC and other EGIDs, there was minimal transcriptomic overlap and minimal evidence of a strong allergic type 2 immune response in EoC compared with other EGIDs. Decreased cell cycle and increased apoptosis in EoC compared with NL were identified by functional enrichment analysis and immunostaining using Ki-67 and cleaved caspase-3. Pericryptal circumferential eosinophil collars were associated with the EoC transcriptome (P < .001). EoC transcriptome-based scores were reversible with disease remission and differentiated EoC from IBD, even after controlling for colonic eosinophil levels (P < .0001).

CONCLUSIONS

We established EoC transcriptomic profiles, identified mechanistic pathways, and integrated findings with parallel IBD and EGID data. These findings establish EoC as a distinct disease compared with other EGIDs and IBD, thereby providing a basis for improving diagnosis and treatment.

Role of IL-18-transformed CD274-expressing eosinophils in promoting airway obstruction in experimental asthma

BACKGROUND

IL-5-dependent residential and IL-18-transformed pathogenic eosinophils have been reported; however, the role of IL-18-transformed CD274-expressing pathogenic eosinophils compared to IL-5-generated eosinophils in promoting airway obstruction in asthma has not yet been examined.

METHODS

Eosinophils are detected by tissue anti-MBP and anti-EPX immunostaining, CD274 expression by flow cytometry, and airway resistance using the Buxco FinePointe RC system.

RESULTS

We show that A. fumigatus-challenged wild-type mice, and different gene-deficient mice including naïve CC10-IL-18-transgenic mice, accumulate mostly peribronchial and perivascular CD274-expressing eosinophils except naïve CD2-IL-5-transgenic mice. Additionally, we show that CD2-IL-5 transgenic mice following rIL-18 treatment accumulate high number of CD274-expressing perivascular and peribronchial eosinophils with induced collagen, goblet cell hyperplasia and airway resistance compared to saline-challenged CD2-IL5 transgenic mice. Furthermore, we also show that even A. fumigatus-challenged IL-5 ^-/- mice and rIL-18 given ΔdblGATA mice accumulate CD274-expressing eosinophil-associated asthma pathogenesis including airway obstruction. Most importantly, we provide evidence that neutralization of CD274 and IL-18 in A. fumigatus-challenged mice ameliorate experimental asthma. Taken together, the data presented are clinically significant in establishing that anti-IL-18 neutralization is a novel immunotherapy to restrict asthma pathogenesis.

CONCLUSIONS

We demonstrate that IL-18 is critical for inducing asthma pathogenesis, and neutralization of CD274 is a potential immunotherapeutic strategy for asthma.

Case Report: Eosinophilic Esophagitis in a Patient With a Novel STAT1 Gain-of-Function Pathogenic Variant

Background

STAT1 gain-of-function (GOF) is a primary immune dysregulatory disorder marked by wide infectious predisposition (most notably chronic mucocutaneous Candidiasis), autoimmunity, vascular disease and malignant predisposition. While atopic features have been described in some STAT1 GOF patients, they are not considered a predominant feature of the disease. Additionally, while eosinophilic gastrointestinal infiltration has been reported in some cases, this has always been described in the context of pre-existing oropharyngeal and/or esophageal Candidiasis.

Clinical cases

Herein, we report 3 members of a multi-generational family diagnosed with STAT1 GOF caused by a novel mutation in the N-terminal domain, c.194A>C (p.D65A). The proband presented initially with a long-standing history of treatment-refractory eosinophilic esophagitis (EoE) without preceding gastrointestinal tract fungal infections, and her mother was diagnosed with esophagitis as well.

Conclusion

EoE has been previously associated with alterations to STAT6 and STAT3 signaling pathways. The current report expands the possible association between JAK/STAT-related disorders and EoE, suggesting that EoE could be a primary disease manifestation of STAT1 GOF, even in the absence of oropharyngeal and/or esophageal Candidiasis.

Pathophysiology of Non-IgE-Mediated Food Allergy

Non-IgE-mediated food allergies are a group of disorders characterized by subacute or chronic inflammatory processes in the gut. Unlike IgE mediated food allergies that may result in multi-organ system anaphylaxis, the non-IgE mediated food allergies primarily affect the gastrointestinal tract. This review outlines the clinical manifestations, epidemiology, pathophysiology, and management of non-IgE-mediated food allergies. An updated literature search of selected non-IgE-mediated food allergies was conducted for this review using PubMed database to the current year (2021). Reviewed disorders include food protein-induced enterocolitis syndrome (FPIES), food-protein enteropathy (FPE), food protein-induced allergic proctocolitis (FPIAP), and eosinophilic gastrointestinal disorders (EGIDs) such as eosinophilic esophagitis (EoE). While extensive gains have been made in understanding FPIES, FPIAP, FPE, and EoE, more information is needed on the pathophysiology of these food allergies. Similarities among them include involvement of innate immunity, T-lymphocyte processes, alteration of the intestinal lumen at the cellular level with the appearance of inflammatory cells and associated histologic changes, and specific cytokine profiles suggesting food-specific, T-cell, and immune-mediated responses. While FPIES and FPIAP typically resolve in early childhood, EGIDs typically do not. Emerging new therapies for EoE offer promise of additional treatment options. Further studies identifying the immunopathogenesis, associated biomarkers, and mechanisms of tolerance are needed to inform prevention, diagnosis and management.

Eosinophilic Esophagitis

Eosinophilic esophagitis is a recently defined condition that has dramatically increased in prevalence in the last several decades. It may occur at any age, but the clinical presentation in young children is often more vague than the classic solid food dysphagia and food impacting that are the major presenting symptoms of eosinophilic esophagitis in adults and adolescents. Successful therapies exist, including medications and dietary modifications, but disease typically recurs when the intervention is discontinued.

Antibiotic-Induced Gut Microbiota Dysbiosis Damages the Intestinal Barrier, Increasing Food Allergy in Adult Mice

(1) Background: The use of antibiotics affects the composition of gut microbiota. Studies have suggested that the colonization of gut microbiota in early life is related to later food allergies. Still, the relationship between altered intestinal microbiota in adulthood and food allergies is unclear. (2) Methods: We established three mouse models to analyze gut microbiota dysbiosis’ impact on the intestinal barrier and determine whether this effect can increase the susceptibility to and severity of food allergy in later life. (3) Results: The antibiotic-induced gut microbiota dysbiosis significantly reduced Lachnospiraceae, Muribaculaceae, and Ruminococcaceae, and increased Enterococcaceae and Clostridiales. At the same time, the metabolic abundance was changed, including decreased short-chain fatty acids and tryptophan, as well as enhanced purine. This change is related to food allergies. After gut microbiota dysbiosis, we sensitized the mice. The content of specific IgE and IgG1 in mice serum was significantly increased, and the inflammatory response was enhanced. The dysbiosis of gut microbiota caused the sensitized mice to have more severe allergic symptoms, ruptured intestinal villi, and a decrease in tight junction proteins (TJs) when re-exposed to the allergen. (4) Conclusions: Antibiotic-induced gut microbiota dysbiosis increases the susceptibility and severity of food allergies. This event may be due to the increased intestinal permeability caused by decreased intestinal tight junction proteins and the increased inflammatory response.

Gene therapy for a murine model of eosinophilic esophagitis

BACKGROUND

Eosinophils are specialized granulocytic effector cells that store and release highly active mediators used in immune defense. Eosinophils are also implicated in the pathogenesis of allergic disorders, including eosinophilic esophagitis (EoE), a chronic disorder characterized by infiltration of eosinophils into the esophagus and release of mediators that damage tissue, resulting in gastrointestinal morbidity, food impaction, and dysphagia. Treatment with elimination diets and/or topical corticosteroid therapy slow disease progression, but are complicated by adverse effects, limited compliance, and loss of response to therapy. We hypothesized that a single administration of an adeno-associated virus (AAV) coding for an anti-eosinophil monoclonal antibody that induces eosinophil clearance (anti-Siglec-F) would treat on a persistent basis a murine model of EoE.

METHODS

A mouse model of peanut-induced EoE that mimics the human disease was established by sensitization and challenge with peanut extract. After challenge, these mice exhibited an EoE phenotype demonstrated by elevated levels of blood eosinophils, infiltration of eosinophils in the esophagus with associated esophageal remodeling and food impaction.

RESULTS

The mice were treated with a single intravenous administration (10¹¹ genome copies) of AAVrh.10mAnti-Eos, a serotype rh.10 AAV vector coding for an anti-Siglec-F monoclonal antibody. Vector administration resulted in persistent, high levels of anti-Siglec-F antibody expression. Administration of AAVrh.10mAnti-Eos to the mouse model of EoE reduced blood (P < 0.02) and esophageal eosinophil numbers (P < 0.002) protected from esophageal tissue remodeling and minimized food impaction.

CONCLUSION

These results suggest that a single treatment with AAVrh.10mAnti-Eos has the potential to provide persistent therapeutic benefit to patients with EoE.

Intestinal eosinophils: multifaceted roles in tissue homeostasis and disease

Intestinal eosinophils are largely considered to be one of the central immune effector cells during helminth infection and disorders such as eosinophilic oesophagitis and food allergies. Given the abundance of these cells present in the gastrointestinal tract at homeostasis, emerging studies now reveal novel roles for eosinophils in the development and regulation of immunity, and during tissue repair. In addition, the identification of distinct eosinophil subsets indicates that we must consider the heterogeneity of these cells and how they differentially participate in mucosal immunity at steady state and during disease. Here, we summarise the literature on intestinal eosinophils, and how they contribute to mucosal homeostasis through immune regulation and interactions with the microbiome. We then explore the divergent roles of eosinophils in the context of eosinophilic gastrointestinal disorders and during helminth infection, whereby we discuss key observations and differences that have emerged from animal models and human studies. Lastly, we consider the possible interactions of eosinophils with the enteric nervous system, and how this represents an exciting area for future research which may inform future therapeutic targets.

A Rare Case of Eosinophilic Gastroenteritis and Ampullitis Leading to Benign Papillary Stenosis

Eosinophilic gastroenteritis is characterized by eosinophilic infiltration of the gastrointestinal wall. There have been limited studies of eosinophilic infiltration involving the ampulla. We present a 70-year-old woman with a history of asthma, eosinophilic esophagitis, and eosinophilic sinusitis, who underwent work up for postprandial abdominal pain and abnormal liver function tests. The patient had various imaging studies done, including computed tomography (CT) scan, magnetic resonance imaging (MRI), and magnetic resonance cholangiopancreatography (MRCP). Dilated extrahepatic bile duct with distal tapering towards the ampulla was noted on MRCP and afterwards on endoscopic ultrasound (EUS). Endoscopic retrograde cholangiopancreatography (ERCP) revealed an inflamed major ampulla with benign papillary stenosis. The patient was treated with sphincterotomy, sphincteroplasty/dilation of distal common bile duct, and placement of an 11.5 Fr × 7 cm plastic stent into the bile duct. Additionally, she was started on prednisone, which was gradually tapered down. The patient demonstrated significant improvement with systemic steroid therapy. Liver function tests (LFTs) completely normalized after ERCP. Ampullitis leading to papillary stenosis secondary to eosinophilic infiltration of the major papilla is a rare manifestation of eosinophilic gastrointestinal disorders (EGIDs). Early diagnosis would lead to appropriate medical and endoscopic management.

Two Cases of Eosinophilic Gastroenteritis With Rare Manifestations Revealed in Medical Checkup Findings

Eosinophilic gastroenteritis (EGE) is characterized by dense infiltration of eosinophils in gastrointestinal tissues, resulting in morphological and functional abnormalities of the gastrointestinal tract. EGE susceptibility is most common among individuals aged 40-50 years old, and hence it is likely that affected patients will be encountered at the time of a medical checkup. In this report, we present two rare cases of EGE that presented interesting manifestations in findings obtained in a fluoroscopic examination performed at an annual medical checkup. Accumulation of case reports is important to provide information to pathologists to enable them to make correct early diagnosis and begin effective treatment at the earliest.

Emerging roles of infiltrating granulocytes and monocytes in homeostasis

The infiltration of naïve tissues by myeloid cells has been long related to their clearance and the physiological cell turnover, however, increasing evidence shows that they can additionally fulfill specific, non-immune functions in different tissues. There is also growing evidence to support that infiltrated granulocytes and monocytes respond to different environments by modulating gene expression and cytokine production, which in turn contribute to the normal function of the host tissue. This review will address the roles of immigrated myeloid cells in different tissues and their crosstalk with the host tissue environments.

Food Allergies

Food allergy is 1 of the 4 manifestations of the "atopic march," along with eczema, allergic rhinitis, and asthma. Depending on the pathophysiologic immune mechanisms behind a food allergy, it can be classified as immunoglobulin E-mediated, non-immunoglobulin E-mediated, or mixed. The prevalence of food allergies has risen worldwide during the past few decades, becoming a significant global health concern. Patients experiencing food allergies and their caregivers are heavily burdened personally, socially, emotionally, and financially. The health-care system is also considerably affected. Pediatricians, as primary health-care providers, are often challenged with these patients, becoming the first-line for the recognition and management of food allergies. The purpose of this review is to provide a comprehensive summary of food allergies, including the most up-to-date information, recent guidelines, and recommendations.

Clinical outcomes of adults with eosinophilic esophagitis with severe stricture

BACKGROUND AND AIMS

Eosinophilic esophagitis (EoE) is an inflammatory disease of the esophagus. Its prevalence has been increasing steadily over the past 3 decades. The prognosis of patients with EoE presenting with severe esophageal strictures is poorly understood. The aim of this study was to describe the clinical outcomes of patients with EoE with severe strictures and identify factors associated with a greater likelihood of improvement in esophageal diameter.

METHODS

This study is a retrospective chart review of patients with EoE with severe stricture, defined as an esophageal diameter of 10 mm or less at one point in their disease course. Each patient's clinical course was followed during standard-of-care follow-up with medical or dietary therapy in conjunction with repeated esophageal dilation. Multivariate regression analysis was performed to determine which variables are associated with endoscopic response, defined by an improvement in esophageal diameter to 13 mm and to 15 mm.

RESULTS

From a cohort of 1091 adults with EoE, severe strictures were identified in 66 patients (7%). Of the 66 patients, 59 (89%) achieved an esophageal diameter of ≥13 mm and 43 (65%) achieved ≥15 mm. Initial diameter (odds ratio, 1.58; 95% confidence interval, 1.06-2.35; P = .025) and histologic remission (odds ratio, 34.97; 95% confidence interval, 6.45-189.49; P < .0001) were significantly associated with achieving a diameter ≥15 mm. Age at diagnosis, gender, and number of months to maximum esophageal diameter were not associated with achieving either diameter.

CONCLUSIONS

Most patients with EoE with severe stricture experienced improvement in esophageal diameter to ≥15 mm with treatment, suggesting that the currently available treatment options are effective for patients with severe strictures. The most significant factors associated with disease reversibility are initial esophageal diameter and histologic remission.

Eosinophilic Esophagitis

Eosinophilic esophagitis is a recently defined condition that has dramatically increased in prevalence in the last several decades. It may occur at any age, but the clinical presentation in young children is often more vague than the classic solid food dysphagia and food impacting that are the major presenting symptoms of eosinophilic esophagitis in adults and adolescents. Successful therapies exist, including medications and dietary modifications, but disease typically recurs when the intervention is discontinued.

Eosinophil depletion suppresses radiation-induced small intestinal fibrosis

Radiation-induced intestinal fibrosis (RIF) is a serious complication after abdominal radiotherapy for pelvic tumor or peritoneal metastasis. Herein, we show that RIF is mediated by eosinophil interactions with α-smooth muscle actin-positive (α-SMA⁺) stromal cells. Abdominal irradiation caused RIF especially in the submucosa (SM) of the small intestine, which was associated with the excessive accumulation of eosinophils in both human and mouse. Eosinophil-deficient mice showed markedly ameliorated RIF, suggesting the importance of eosinophils. After abdominal irradiation, chronic crypt cell death caused elevation of extracellular adenosine triphosphate, which in turn activated expression of C-C motif chemokine 11 (CCL11) by pericryptal α-SMA⁺ cells in the SM to attract eosinophils in mice. Inhibition of C-C chemokine receptor 3 (CCR3) by genetic deficiency or neutralizing antibody (Ab) treatment suppressed eosinophil accumulation in the SM after irradiation in mice, suggesting a critical role of the CCL11/CCR3 axis in the eosinophil recruitment. Activated α-SMA⁺ cells also expressed granulocyte-macrophage colony-stimulating factor (GM-CSF) to activate eosinophils. Transforming growth factor-β1 from GM-CSF-stimulated eosinophils promoted collagen expression by α-SMA⁺ cells. In translational studies, treatment with a newly developed interleukin-5 receptor α-targeting Ab, analogous to the human agent benralizumab, depleted intestinal eosinophils and suppressed RIF in mice. Collectively, we identified eosinophils as a crucial factor in the pathogenesis of RIF and showed potential therapeutic strategies for RIF by targeting eosinophils.

Eosinophilic gastroenteritis: diagnosis and clinical perspectives

Eosinophilic gastroenteritis (EGE) is a digestive disorder in children and adults that is characterized by eosinophilic infiltration in the stomach and intestine. The underlying molecular mechanisms predisposing to this disease are unknown, but it seems that hypersensitivity response plays a major role in its pathogenesis, as many patients have a history of seasonal allergies, food sensitivities, asthma, and eczema. Symptoms and clinical presentations vary, depending on the site and layer of the gastrointestinal wall infiltrated by eosinophils. Laboratory results, radiological findings, and endoscopy can provide important diagnostic evidence for EGE; however, the cornerstone of the diagnosis remains the histological examination of gastric and duodenal specimens for evidence of eosinophilic infiltration (>20 eosinophils per high-power field), and finally clinicians make the diagnosis in correlation with and by exclusion of other disorders associated with eosinophilic infiltration. Although spontaneous remission is reported in around 30%–40% of EGE cases, most patients require ongoing treatment. The management options for this disorder include both dietary and pharmacological approaches, with corticosteroids being the mainstay of therapy and highly effective. The subsequent course is quite variable. Some patients have no recurrences, while a few experience recurrent symptoms during or immediately after corticosteroid interruption. An alternative therapeutic armamentarium includes mast-cell stabilizers, leukotriene antagonists, antihistamines, immunomodulators, and biological agents. In this review, we provide a summary of the different diagnostic tools utilized in practice, as well as the different therapeutic approaches available for EGE management.

Activated Eosinophils Exert Antitumorigenic Activities in Colorectal Cancer

Immunotherapies targeting T lymphocytes are revolutionizing cancer therapy but only benefit a subset of patients, especially in colorectal cancer. Thus, additional insight into the tumor microenvironment (TME) is required. Eosinophils are bone marrow-derived cells that have been largely studied in the context of allergic diseases and parasite infections. Although tumor-associated eosinophilia has been described in various solid tumors including colorectal cancer, knowledge is still missing regarding eosinophil activities and even the basic question of whether the TME promotes eosinophil recruitment without additional manipulation (e.g., immunotherapy) is unclear. Herein, we report that eosinophils are recruited into developing tumors during induction of inflammation-induced colorectal cancer and in mice with the Apc^{min /+} genotype, which develop spontaneous intestinal adenomas. Using adoptive transfer and cytokine neutralization experiments, we demonstrate that the TME supported prolonged eosinophil survival independent of IL5, an eosinophil survival cytokine. Tumor-infiltrating eosinophils consisted of degranulating eosinophils and were essential for tumor rejection independently of CD8⁺ T cells. Transcriptome and proteomic analysis revealed an IFNγ-linked signature for intratumoral eosinophils that was different from that of macrophages. Our data establish antitumorigenic roles for eosinophils in colorectal cancer. These findings may facilitate the development of pharmacologic treatments that could unleash antitumor responses by eosinophils, especially in colorectal cancer patients displaying eosinophilia.

Augmentation of the expression of the eotaxin receptor on duodenal neutrophils by IL-21

Inflammation can occur via different mechanisms, such as via acute and chronic responses, on numerous occasions and function accordingly through various roles. There are more than five subsets of neutrophils; neutrophilic heterogeneity is modulated by the inflammatory condition. To understand the characteristics of inflammation, identification of atypical neutrophils is important. In this study, we found that the expression of eotaxin receptor (CD193) on atypical neutrophils in the duodenum is augmented in IL-21 isoform transgenic (Tg) mice. In a series of studies, we have established a Tg mouse strain to further investigate the functions of IL-21 in vivo. Interestingly, Tg mice immunized with ovalbumin (OVA) were more sensitive to OVA-induced systemic anaphylaxis as compared with wild type mice with duodenal and splenic gross congestion. Further analysis conducted in the duodenum of Tg mice revealed that only the number of neutrophils migrating into the duodenum was significantly increased prior to immunization. Previous studies have shown that the gastrointestinal compartment and the spleen constantly produce eotaxin, which regulates basal levels of tissue eosinophils. Therefore, we analyzed CD193 expression on neutrophils and eosinophils. As expected, its expression by duodenal neutrophils was upregulated in Tg mice. Furthermore, the addition of IL-21 into bone marrow cell culture increased the number of CD193⁺ neutrophils, which easily migrated into the duodenum. These observations suggested that CD193⁺ neutrophils increase in number under inflammatory conditions due to chronic IL-21 production.

Pharmacologic Treatment of Eosinophilic Esophagitis: An Update

Eosinophilic esophagitis (EoE) is defined as a chronic, immune-medicated or antigen-mediated, esophageal disease, characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation. Food allergens are identified in most patients. Treatment strategies include elimination diets, drugs, and esophageal dilation. This article focuses on pharmacologic treatment. Currently, there is no pharmacologic treatment that has been approved by regulatory authorities. Established pharmacologic options to treat EoE include proton pump inhibitors and swallowed topical steroids. Several biologic therapies are currently under evaluation and some of them have shown promising results in improving biologic endpoints and patient-reported outcomes.

Functions of tissue-resident eosinophils

Eosinophils are a prominent cell type in particular host responses such as the response to helminth infection and allergic disease. Their effector functions have been attributed to their capacity to release cationic proteins stored in cytoplasmic granules by degranulation. However, eosinophils are now being recognized for more varied functions in previously underappreciated diverse tissue sites, based on the ability of eosinophils to release cytokines (often preformed) that mediate a broad range of activities into the local environment. In this Review, we consider evolving insights into the tissue distribution of eosinophils and their functional immunobiology, which enable eosinophils to secrete in a selective manner cytokines and other mediators that have diverse, 'non-effector' functions in health and disease.

Prevalence of atopic disease in patients with eosinophilic esophagitis

BACKGROUND

The objective of this work was to evaluate prevalence of eosinophilic esophagitis (EoE) in the United States, and analyze prevalence of atopic disease in patients with EoE. The study design was a retrospective administrative database analysis in U.S.-based outpatient settings.

METHODS

A retrospective claims analysis in the inpatient and outpatient setting (using MarketScan) was conducted to analyze prevalence of atopic disease diagnoses in patients with EoE in 2012, and timing of those diagnoses vs EoE.

RESULTS

From published evidence, prevalence of EoE was estimated at 1 to 5 patients per 10,000 and prevalence of asthma, allergic rhinitis (AR), and atopic dermatitis (AD) concurrent to EoE ranged from 20% to 50%, 50% to 75%, and 2% to 19% cases, respectively. From 2009 and 2013, the estimated prevalence of EoE in MarketScan increased from 2.7 to 5.6 per 10,000 enrollees age 34.5 ± 18.43 years (mean ± standard deviation). Age followed a bimodal distribution with peaks at 12 and 41 years. Women accounted for 35.6% cases. Prevalence of asthma, AR, AD, and food allergies up to 12 months post-EoE diagnosis reached 44.7%, 27.1%, 25.2%, and 16.9%, respectively, with 63.5% of all patients suffering from at least 1 of these 4 diseases and 3.0% suffering from all 4.

CONCLUSION

The diagnosis of EoE is associated with the diagnoses of asthma, AR, AD, and food allergies. The high prevalence of these conditions in EoE patients further strengthens the hypothesis of a common pathogenesis.

Pediatric Tourette Syndrome: A Tic Disorder with a Tricky Presentation

Dysphagia is a condition in which disruption of the swallowing process interferes with a patient's ability to eat. This may result in coughing or choking while swallowing, food sticking in the throat, or globus sensation. Eosinophilic esophagitis (EoE) is a chronic immune-mediated disease with a varied clinical spectrum of symptoms including dysphagia. Tourette syndrome (TS) is an inherited neurological disorder that manifests itself as a series of motor and vocal tics and may include oropharyngeal dysphagia. Dysphagia as a result of TS generally affects female, elderly patients and is not reported in children. While the pathophysiology is relatively unknown, experts believe TS is closely linked to damage or abnormalities in the basal ganglia of the brain. We present this interesting pediatric case of dysphagia due to EoE, which had been previously thought to be related to the patient's TS.

Assessment of eosinophil peroxidase as a potential diagnostic and prognostic marker in dogs with inflammatory bowel disease

OBJECTIVE To evaluate a method for identifying intact and degranulated eosinophils in the small intestine of dogs with inflammatory bowel disease (IBD) by use of a monoclonal antibody (mAb) against eosinophil peroxidase (EPX). ANIMALS 11 untreated dogs with IBD, 5 dogs with IBD treated with prednisolone, and 8 control dogs with no clinical evidence of gastrointestinal tract disease and no immunosuppressive treatment. PROCEDURES 4-μm-thick sections of paraffin-embedded tissues from necropsy specimens were immunostained with EPX mAb. Stained intact and degranulated eosinophils in consecutive microscopic fields (400X magnification) of the upper (villus tips) and lower (between the muscularis mucosae and crypts) regions of the lamina propria of the jejunum were manually counted. RESULTS Compared with control and treated IBD dogs, untreated IBD dogs had a significantly higher number of degranulated eosinophils in the lower region of the lamina propria. However, no significant differences were detected in the number of intact eosinophils in this region among groups. In the upper region of the lamina propria, untreated IBD dogs had a significantly higher number of degranulated and intact eosinophils, compared with control and treated IBD dogs. Number of degranulated and intact eosinophils did not differ significantly between control and treated IBD dogs. CONCLUSIONS AND CLINICAL RELEVANCE Immunohistologic analysis with EPX mAb yielded prominent granule staining that allowed reliable morphological identification of degranulated and intact eosinophils, which may provide a strategy for quantitative and selective evaluation of eosinophils in gastrointestinal biopsy specimens and a potential method to diagnose IBD and evaluate treatment outcome.

Eosinophilic Esophagitis: Impact of Latest Insights Into Pathophysiology on Therapeutic Strategies

Eosinophilic esophagitis (EoE) has been defined as a 'chronic, immune/antigen-mediated, esophageal disease, characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation'. A peak value of ≥15 eosinophils/high power field has been defined as histologic diagnostic cutoff. Other conditions associated with esophageal eosinophilia, such as gastro-esophageal reflux disease, PPI-responsive esophageal eosinophilia or Crohn's disease, need to be ruled out before EoE can be diagnosed. Males are affected more frequently than females and most of the patients have concomitant allergies. Currently, the EoE prevalence is about 1 of 2,000 inhabitants in Westernized countries. The first EoE patients were described only 2 decades ago. Despite this short period, considerable progress has been made regarding the understanding of the pathophysiology, natural history, assessment of disease activity and with respect to evaluating different therapeutic options. Untreated EoE can lead to esophageal remodeling with reduced compliance and stricture formation, which represents the main risk factor for food bolus impactions. The therapeutic options can be summarized with the 3 D's, which stand for drugs, diets and dilation. Of note, as of yet, there is no EoE-specific drug that has been approved by regulatory authorities. This is, among other reasons, related to the lack of validated outcome measurement instruments until recently. Swallowed topical steroids such as budesonide or fluticasone represent the standard of care for treating symptomatic pediatric and adult EoE patients with inflammatory activity. Several trials have already evaluated different biologic therapies, such as anti-interleukin-5 or anti-IgE. Further studies are on the way. As a non-pharmacologic alternative, different dietary regimens exist. Dilation can offer long-lasting symptomatic response in case of stricturing EoE but does not have any impact on the underlying inflammation. This review highlights the latest insights regarding pathophysiology and its impact regarding current and future therapeutic strategies.

Eosinophils may play regionally disparate roles in influencing IgA(+) plasma cell numbers during large and small intestinal inflammation

Background

Eosinophils are innate immune cells present in the intestine during steady state conditions. An intestinal eosinophilia is a hallmark of many infections and an accumulation of eosinophils is also observed in the intestine during inflammatory disorders. Classically the function of eosinophils has been associated with tissue destruction, due to the release of cytotoxic granule contents. However, recent evidence has demonstrated that the eosinophil plays a more diverse role in the immune system than previously acknowledged, including shaping adaptive immune responses and providing plasma cell survival factors during the steady state. Importantly, it is known that there are regional differences in the underlying immunology of the small and large intestine, but whether there are differences in context of the intestinal eosinophil in the steady state or inflammation is not known.

Results

Our data demonstrates that there are fewer IgA⁺ plasma cells in the small intestine of eosinophil-deficient ΔdblGATA-1 mice compared to eosinophil-sufficient wild-type mice, with the difference becoming significant post-infection with Toxoplasma gondii. Remarkably, and in complete contrast, the absence of eosinophils in the inflamed large intestine does not impact on IgA⁺ cell numbers during steady state, and is associated with a significant increase in IgA⁺ cells post-infection with Trichuris muris compared to wild-type mice. Thus, the intestinal eosinophil appears to be less important in sustaining the IgA⁺ cell pool in the large intestine compared to the small intestine, and in fact, our data suggests eosinophils play an inhibitory role. The dichotomy in the influence of the eosinophil over small and large intestinal IgA⁺ cells did not depend on differences in plasma cell growth factors, recruitment potential or proliferation within the different regions of the gastrointestinal tract (GIT).

Conclusions

We demonstrate for the first time that there are regional differences in the requirement of eosinophils for maintaining IgA+ cells between the large and small intestine, which are more pronounced during inflammation. This is an important step towards further delineation of the enigmatic functions of gut-resident eosinophils.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-016-0153-0) contains supplementary material, which is available to authorized users.

Elements Involved In Promoting Eosinophilic Gastrointestinal Disorders

Eosinophilic gastrointestinal disorders (EGID) are food allergen-induced allergic gastrointestinal disorders, characterized by accumulation of highly induced eosinophils in different segments of gastrointestinal tract along with eosinophil microabssess and extracellular eosinophilic granules in the epithelial layer. EGID are both IgE- and cell-mediated group of diseases that include eosinophilic esophagitis (EoE), eosinophilic gastritis (EG), eosinophilic gastroenteritis (EGE) and eosinophilic colitis (EC). Despite the increased incidences and considerable progress made in understanding EGID pathogenesis. The mechanism is still not well understood. It has been shown that IL-4, IL-5, IL-13, IL-15, IL-18, eotaxin-1, eotaxin-2 and eotaxin-3 play a critical role in EGID pathogenesis. Currently, the only criterion for diagnosing EoE, EGE and EC are repetitive endoscopic and histopathological evaluation of biopsies along with other clinical characteristics/manifestations. Antigen elimination and corticosteroid therapies are the most effective therapies currently in practice for the treatment of EGID. The cytokines (anti-IL-5 and anti-IL-13) therapy trials were not very successful in case of EoE. Most recently, a clinical trial using anti-IL-13 reported only 60% reduced esophageal eosinophilia without achieving primary endpoint. This clinical finding is not surprising and is in accordance with our earlier report indicating that IL-13 is not critical in the initiation of EoE. Notably, EGID still has no reliable noninvasive diagnostic biomarkers. Hence, there is a great necessity to identify novel noninvasive diagnostic biomarkers that can easily diagnose EGID and provide an effective therapy. Now, the attention is required to target cell types like iNKT cells that produce eosinophil active cytokines and is found induced in the pathogenesis of both experimental and human EoE. iNKT cell neutralization is shown to protect allergen-induced EoE in experimental model. In this review, we have discussed the key elements that are critical in the disease initiation, progression, pathogenesis and important for future diagnostic and therapeutic interventions for EGID.

An Atypical Case of Eosinophilic Gastroenteritis Presenting as Hypovolemic Shock

Eosinophilic gastroenteritis is an uncommon condition characterized by focal or diffuse infiltration of eosinophils in the gastrointestinal tract in the absence of secondary causes. The pathogenesis of this condition is not well understood and its clinical presentation depends on the segment and layer of the gastrointestinal tract affected. The definition of eosinophilic gastroenteritis may be difficult, as the normal ranges of eosinophil numbers in normal and abnormal gastric and intestinal mucosa are not standardized. We present the case of a 59-year-old male who came to the hospital with hypovolemic shock and lethargy secondary to severe diarrhea. Laboratory analysis was significant for peripheral eosinophilia, and pathology from both the duodenum and colon showed marked eosinophilic infiltration.

Heterogeneity across the murine small and large intestine

The small and large intestine of the gastrointestinal tract (GIT) have evolved to have discrete functions with distinct anatomies and immune cell composition. The importance of these differences is underlined when considering that different pathogens have uniquely adapted to live in each region of the gut. Furthermore, different regions of the GIT are also associated with differences in susceptibility to diseases such as cancer and chronic inflammation. The large and small intestine, given their anatomical and functional differences, should be seen as two separate immunological sites. However, this distinction is often ignored with findings from one area of the GIT being inappropriately extrapolated to the other. Focussing largely on the murine small and large intestine, this review addresses the literature relating to the immunology and biology of the two sites, drawing comparisons between them and clarifying similarities and differences. We also highlight the gaps in our understanding and where further research is needed.

Ultrastructural features of eosinophilic oesophagitis: impact of treatment on desmosomes

AIMS

A growing body of evidence suggests a role for altered epithelial barrier function in the pathophysiology of eosinophilic oesophagitis (EoE), but few have described the epithelial structure during inflammation. The purpose of this study was to define ultrastructural features of active, inactive EoE and control subject's oesophageal epithelia.

METHODS

We prospectively enrolled patients undergoing diagnostic upper endoscopy for evaluation of EoE. Mucosal pinch biopsies were obtained from the distal oesophagus and processed for routine histology and electron microscopic assessment. Clinical features of enrolled subjects were analysed and subjects were divided into four groups: normal, gastroesophageal reflux disease (GERD), inactive EoE and active EoE. Representative photomicrographs of the basal and superficial epithelia were reviewed for abnormalities. Desmosomes were quantified on the surface of epithelia three to four prickle-cell layers above the basal layer.

RESULTS

Twenty-nine paediatric cases (ages 2-18 years) were enrolled in the study. We observed a significant decrease in the number of desmosomes per cell (DPC) of subjects with active EoE compared with inactive EoE, GERD and normal epithelia. With respect to DPC, no significant differences were found between inactive EoE compared with GERD or normal subjects. Additional ultrastructural features observed included epithelial microplicae and evidence of eosinophil transmigration, degranulation, and sombrero formation.

CONCLUSIONS

Consistent with clinical and molecular findings, our ultrastructural data provide support for an altered oesophageal barrier in paediatric cases with active EoE, which may improve following treatment.

Canine eosinophilic gastrointestinal disorders

Eosinophils play a crucial role in the inflammatory response in conjunction with both innate and adaptive immunity. Eosinophils have long been recognized as inflammatory leukocytes that are particularly important in patients with parasitic infestations. However, recent studies in veterinary medicine demonstrate a number of canine eosinophilic gastrointestinal (GI) disorders unrelated to a parasitic infestation. Although the underlying pathophysiology behind eosinophilic infiltration of the canine GI tract remains uncertain, medical intervention aiming to decrease the activation of eosinophils seems effective in reducing symptoms and preventing organ damage. This review focuses on the biology of eosinophils and their products. It describes, the composition of eosinophil granules, mechanisms of eosinophil activation, and eosinophil-related disease processes leading to organ damage. Even though the main clinical signs of canine eosinophilic gastroenteritis, vomiting and diarrhea, are similar to those of other types of gastroenteritis, the clinical response and prognosis are worse for this condition. The clinical signs and diagnostic approach for eosinophilic GI disorders are described and compared between canine and human patients for each region of GI tract, from the esophagus to the colon. Moreover, the current treatments for this syndrome in canine and human patients are summarized and paralleled. The comparative study of canine and human patients with eosinophilic gastroenteritis will advance the understanding of this syndrome in both species and may lead to the development of novel treatment strategies.

Diagnostic and therapeutic strategies for eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a recently recognized allergic disorder, characterized by eosophageal dysfunction, accumulation of ≥15 eosinophils/high-powered field, eosinophil microabssess, basal cell hyperplasia, extracellular eosinophilic granules in the esophageal epithelial mucosal biopsy and a lack of response to a 8-week proton pump inhibitor treatment. Despite the increased incidences and considerable progress made in understanding EoE pathogenesis, there are limited diagnostic and therapeutic options available for EoE. Currently, the only criterion for diagnosing EoE is repetitive esophageal endoscopic biopsies and histopathological evaluation. Antigen elimination or corticosteroid therapies are effective therapies for EoE but are expensive and have limitations, if continued in the long term. Hence, there is a great necessity for novel noninvasive diagnostic biomarkers that can easily diagnose EoE and assess effectiveness of therapy. Herein, we have provided an update on key molecules involved in the disease initiation, and progression and proposed novel noninvasive diagnostic molecules and strategies for EoE therapy.

CMRF35-like molecule 1 (CLM-1) regulates eosinophil homeostasis by suppressing cellular chemotaxis

Eosinophil accumulation in health and disease is a hallmark characteristic of mucosal immunity and type 2 helper T cell (Th2) inflammation. Eotaxin-induced CCR3 (chemokine (C-C motif) receptor 3) signaling has a critical role in eosinophil chemotactic responses. Nevertheless, the expressions of immunoreceptor tyrosine-based inhibitory motif-bearing receptors such as CMRF35-like molecule-1 (CLM-1) and their ability to govern eosinophil migration are largely unknown. We now report that CLM-1 (but not CLM-8) is highly and distinctly expressed by colonic and adipose tissue eosinophils. Furthermore, Clm1⁻/⁻ mice display elevated baseline tissue eosinophilia. CLM-1 negatively regulated eotaxin-induced eosinophil responses including eosinophil chemotaxis, actin polymerization, calcium influx, and extracellular signal-regulated kinase (ERK)-1/2, but not p38 phosphorylation. Addition of CLM-1 ligand (e.g., phosphatidylserine) rendered wild-type eosinophils hypochemotactic in vitro and blockade of CLM-1/ligand interactions rendered wild-type eosinophils hyperchemotactic in vitro and in vivo in a model of allergic airway disease. Interestingly, suppression of cellular recruitment via CLM-1 was specific to eosinophils and eotaxin, as leukotriene B₄ (LTB₄)- and macrophage inflammatory protein-1α (MIP-1α)-induced eosinophil and neutrophil migration were not negatively regulated by CLM-1. Finally, peripheral blood eosinophils obtained from allergic rhinitis patients displayed elevated CLM-1/CD300f levels. These data highlight CLM-1 as a novel regulator of eosinophil homeostasis and demonstrate that eosinophil accumulation is constantly governed by CLM-1, which negatively regulates eotaxin-induced eosinophil responses.

Value of allergy tests for the diagnosis of food allergy

Eosinophilic esophagitis (EoE) is a chronic T helper 2-type inflammatory disorder. Concurrent allergic diseases have been observed in EoE cases at a high prevalence. The observation that EoE responds to dietary treatment suggests that EoE is an antigen-driven process. However, the pathogenesis by which allergens mediate the eosinophilic disease in the esophagus needs further clarification. In immediate-type food allergy, diagnosis is based on a careful case history followed by a search for food-specific IgE either by skin testing [skin prick test (SPT)] or in vitro (e.g. ImmunoCAP). In children with atopic dermatitis and a food allergy to milk, eggs, peanuts, fish or wheat, the SPT and in vitro determination of specific IgE show excellent sensitivity and negative predictive values, whereas the positive predictive values are low. In pollen-related secondary food allergy, sensitivity and negative predictive values of IgE testing is much lower. Consequently, oral food provocation is the gold standard for the diagnosis of food allergy. Similarly, in EoE patients, SPT, atopy patch test and in vitro determination of IgE to foods do not reliably predict food allergy, and the average positive predictive values of these allergy tests are below 50%. In conclusion, the value of allergy tests to identify triggering foods are limited, and triggering foods have to be identified by an elimination diet and consequent reintroduction of single foods under biopsy control. However, due to the high prevalence of concurrent allergic diseases among EoE patients, an allergy work-up is urgently indicated in each patient with EoE.

Eosinophilic esophagitis: an immune-mediated esophageal disease

Eosinophilic esophagitis (EoE) is an emerging disease defined by esophageal dysfunction, by typical endoscopic findings and by abnormal eosinophilic inflammation within the esophagus. Eosinophilic accumulation in the esophagus occurs as a result of esophageal overexpression of pro-inflammatory mediators, including T cells and mast cells, cytokines such as interleukin (IL)-13, IL-5 and IL-15, as well as chemoattractants (eotaxin and transforming growth factor-β1, fibroblast growth factor and the newly characterized gene--thymic stromal lymphopoietin, which is a key regulator of allergic sensitization initiation). The role of allergy, particularly food allergy in EoE is indisputable, as elimination diet is a proven commonly used treatment for the disease. However, unlike classical immediate IgE-mediated reaction to allergen, EoE is associated with an altered immune response, characterized by a combination of IgE-mediated and non-IgE-mediated mechanisms. In this review, we aim to discuss the many typical aspects of EoE as opposed to other entities involving the esophagus, with focusing on the aberrant immune-mediated key players contributing to the pathogenesis of this unique disease.

The effects of montelukast on eosinophilic gastroenteritis in a mouse model

Gastrointestinal eosinophilic (EG) is a rare and heterogeneous condition characterized by patchy or diffuse eosinophilic infiltration of gastrointestinal tissue. Pharmacological study so far has demonstrated that montelukast, an oral leukotriene receptor antagonist, might be considered in patients with this disease. The aim of this study was to evaluate the effect of montelukast on oral ovalbumin (OVA) allergen induced EG inflammation in mice and to suggest some mechanisms underlying this effect. Twenty-four mice were divided into three experimental groups: PBS control, OVA group, and montelukast treated group. The mice were sensitized intraperitoneally and challenged intragastrically with OVA, and were treated with montelukast. Gastrointestinal symptoms were observed after challenged intragastrically with OVA. Eosinophils count in blood, serum OVA specific IgE and gastrointestinal histology were evaluated. Montelukast could significantly reduce the severity of oral allergen-induced eosinophilic inflammation, villous atrophy, and associated symptoms of weight loss associated with diarrhea. Montelukast also could ameliorate OVA-induced gastrointestinal pathological lesions, which was associated with the decrease of IgE and LTD4 levels, and this might be one of the important mechanisms of montelukast that protected gastrointestinal injury from EG. These findings indicated that montelukast therapy may be a novel therapeutic approach for EG and other eosinophil-mediated diseases.

Significance of para-esophageal lymph nodes in food or aeroallergen-induced iNKT cell-mediated experimental eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a recently recognized inflammatory disorder driven by food hypersensitivity; however, the specific foods and mechanisms involved are unclear. In patients with EoE, we have found that hypersensitivities to corn and peanuts are the most common. Accordingly, we sensitized and exposed mice either intranasally or intragastrically with corn or peanut extract or saline. Esophageal eosinophilia, the genes of eosinophil-directed cytokines, and allergen-induced antibodies were examined in mice challenged with corn or peanut extract or saline. A high number of esophageal lamina propria eosinophils as well as eosinophilic microabscesses, intraepithelial eosinophils, extracellular eosinophilic granules, thickened and disrupted epithelial mucosa, and mast cell hyperplasia were observed in the esophagus of peanut or corn allergen-challenged mice. Mechanistic analysis indicated that para-esophageal lymph nodes might be critical in the trafficking of eosinophils to the esophagus and in EoE association to airway eosinophilia. Furthermore, experimentation with gene-targeted mice revealed that peanut allergen-induced EoE was dependent on eotaxin and invariant natural killer T (iNKT) cells, as CD1d and eotaxin-1/2 gene-deficient mice were protected from disease induction. Thus we provide evidence that para-esophageal lymph nodes are involved in food- or aeroallergen-induced eosinophilia and patchy EoE pathogenesis, likely a mechanism dependent on eotaxins and iNKT cells.

Immunobiology of intestinal eosinophils - a dogma in the changing?

Infiltration of eosinophils into the intestinal mucosa is a typical hallmark of antiparasite immune responses and inflammatory disorders of the intestinal tract, and eosinophils are thought to contribute to these processes by release of their cytotoxic granule content. However, utilizing novel tools to study eosinophils, it has been recognized that eosinophils are constitutively present in the gastrointestinal tract. In addition, as the dogmatic antiparasite function of eosinophils has proven difficult to document experimentally, it has become increasingly clear that eosinophils are likely to have a more complex role than previously appreciated. Thus, the prevailing dogma of eosinophils merely as antiparasitic effector cells is changing. Instead, it has been suggested that eosinophils can contribute also to several other processes in the intestinal mucosa, e.g. local tissue homeostasis and adaptive immune responses. This review describes the current knowledge regarding the characteristics and functions of intestinal eosinophils, and the regulation of eosinophil trafficking to the intestinal mucosa during the steady state and inflammation. Finally, potential additional and new roles of intestinal eosinophils in the intestinal mucosal immune system are discussed.

Eosinophilic esophagitis: trials and tribulations

Eosinophilic esophagitis (EE) is a recently recognized form of pan-esophagitis, which is characterized by the presence of at least 15 eosinophils per high power field on esophageal histology. EE is closely associated with atopic disorders and occurs predominantly in male patients. Young children are more likely to be sensitized to food allergens whilst aeroallergen sensitization predominates in older children and adults--a pattern reminiscent of the "atopic march". EE presents with a diverse range of gastrointestinal symptoms, including regurgitation, vomiting, feeding difficulties or refusal in infancy, in addition to dysphagia and food bolus impaction in older children and adults. The diagnosis may also be ascertained incidentally in patients undergoing gastroscopy for other suspected gastrointestinal conditions, such as gastroesophageal reflux disease or celiac disease. Complications mainly relate to subepithelial remodeling and fibrosis which may result in dysmotility, dysphagia and esophageal strictures. The proportion of EE patients at risk of these complications is unknown due to a paucity of data on the natural history of EE. There are only few randomized controlled trials assessing the efficacy of treatment modalities for EE, which currently either involve food allergen elimination or use of swallowed aerosolized corticosteroids. This article aims to discuss the complex issues of the diagnosis and long-term management that confront clinicians who care for children with EE.

Emerging management concepts for eosinophilic esophagitis in children

Eosinophilic esophagitis (EoE) is a newly recognized condition that appears to be increasing in incidence for as yet unknown reasons. It can occur at any age and presents both to gastroenterologists and allergists. Clinical manifestations range from gastrointestinal symptoms (vomiting, feeding difficulties, dysphagia or food bolus impaction) to co-existing atopic conditions (asthma, allergic rhinitis or eczema). The diagnosis requires demonstration of at least 15 eosinophils per high power field on esophageal histology, usually in the context of resistance to proton pump inhibitor treatment or a normal 24-h esophageal pH monitoring study. The differential diagnosis between EoE and gastroesophageal reflux disease (GERD) can be problematic as there is significant clinical overlap between both conditions. Although difficult-to-manage esophageal strictures are well recognized in patients with long-standing EoE, little is known about risk factors for the development of this complication. There is a paucity of data on both the natural history and optimal long-term management of EoE. Current treatment options include food allergen elimination diets, use of topical aerosolized corticosteroids, or a combination of the two. Pediatric case studies have been provided to illustrate the complexity of decision points that often arise in the management of these patients. This paper aims to discuss the various strategies currently available to clinicians in the management of EoE and highlights gaps in the current evidence base that urgently require further research.