Invariant natural killer T cells in children with eosinophilic esophagitis

Potential Aspects of the Use of Cytokines in Atopic Dermatitis

Atopic dermatitis (AD) is an abnormal inflammatory response in the skin to food, environmental IgE, or non-IgE allergens. This disease belongs to a group of inflammatory diseases that affect both children and adults. In highly developed countries, AD is diagnosed twice as often in children than in adults, which may possibly be connected to increased urbanization. The immune system's pathomechanisms of AD involve humoral mechanisms with IgE, cellular T lymphocytes, dendritic cells occurring in the dermis, Langerhans cells occurring in the epidermis, and other cells infiltrating the site of inflammation (eosinophils, macrophages, mast cells, neutrophils, and basophils). Cytokines are small proteins that affect the interaction and communication between cells. This review characterizes cytokines and potential aspects of the treatment of atopic dermatitis, as well as new strategies that are currently being developed, including targeting cytokines and their receptors.

Mononuclear cell composition and activation in blood and mucosal tissue of eosinophilic esophagitis

Introduction

Eosinophilic esophagitis (EoE) is a chronic, inflammatory, antigen-driven disease of the esophagus. Tissue EoE pathology has previously been extensively characterized by novel transcriptomics and proteomic platforms, however the majority of surface marker determination and screening has been performed in blood due to mucosal tissue size limitations. While eosinophils, CD4+ T cells, mast cells and natural killer (NK) T cells were previously investigated in the context of EoE, an accurate picture of the composition of peripheral blood mononuclear cells (PBMC) and their activation is missing.

Methods

In this study, we aimed to comprehensively analyze the composition of peripheral blood mononuclear cells and their activation using surface marker measurements with multicolor flow cytometry simultaneously in both blood and mucosal tissue of patients with active EoE, inactive EoE, patients with gastroesophageal reflux disease (GERD) and controls. Moreover, we set out to validate our data in co-cultures of PBMC with human primary esophageal epithelial cells and in a novel inducible mouse model of eosinophilic esophagitis, characterized by extensive IL-33 secretion in the esophagus.

Results

Our results indicate that specific PBMC populations are enriched, and that they alter their surface expression of activation markers in mucosal tissue of active EoE. In particular, we observed upregulation of the immunomodulatory molecule CD38 on CD4+ T cells and on myeloid cells in biopsies of active EoE. Moreover, we observed significant upregulation of PD-1 on CD4+ and myeloid cells, which was even more prominent after corticosteroid treatment. With co-culture experiments we could demonstrate that direct cell contact is needed for PD-1 upregulation on CD4+ T cells. Finally, we validated our findings of PD-1 and CD38 upregulation in an inducible mouse model of EoE.

Discussion

Herein we show significant alterations in the PBMC activation profile of patients with active EoE in comparison to inactive EoE, GERD and controls, which could have potential implications for treatment. To our knowledge, this study is the first of its kind expanding the multi-color flow cytometry approach in different patient groups using in vitro and in vivo translational models.

Mechanistic Insights into Eosinophilic Esophagitis: Therapies Targeting Pathophysiological Mechanisms

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease characterized by eosinophilic infiltration of the esophagus. It arises from a complex interplay of genetic predisposition (susceptibility loci), environmental triggers (allergens and dietary antigens), and a dysregulated immune response, mainly mediated by type 2 T helper cell (Th2)-released cytokines, such as interleukin (IL)-4, IL-5, and IL-13. These cytokines control eosinophil recruitment and activation as well as tissue remodeling, contributing to the characteristic features of EoE. The pathogenesis of EoE includes epithelial barrier dysfunction, mast cell activation, eosinophil degranulation, and fibrosis. Epithelial barrier dysfunction allows allergen penetration and promotes immune cell infiltration, thereby perpetuating the inflammatory response. Mast cells release proinflammatory mediators and promote eosinophil recruitment and the release of cytotoxic proteins and cytokines, causing tissue damage and remodeling. Prolonged inflammation can lead to fibrosis, resulting in long-term complications such as strictures and dysmotility. Current treatment options for EoE are limited and mainly focus on dietary changes, proton-pump inhibitors, and topical corticosteroids. Novel therapies targeting key inflammatory pathways, such as monoclonal antibodies against IL-4, IL-5, and IL-13, are emerging in clinical trials. A deeper understanding of the complex pathogenetic mechanisms behind EoE will contribute to the development of more effective and personalized therapeutic strategies.

Type 1 invariant natural killer T cells in chronic inflammation and tissue fibrosis

Chronic tissue inflammation often results in fibrosis characterized by the accumulation of extracellular matrix components remodeling normal tissue architecture and function. Recent studies have suggested common immune mechanisms despite the complexity of the interactions between tissue-specific fibroblasts, macrophages, and distinct immune cell populations that mediate fibrosis in various tissues. Natural killer T (NKT) cells recognizing lipid antigens bound to CD1d molecules have been shown to play an important role in chronic inflammation and fibrosis. Here we review recent data in both experimental models and in humans that suggest a key role of type 1 invariant NKT (iNKT) cell activation in the progression of inflammatory cascades leading to recruitment of neutrophils and activation of the inflammasome, macrophages, fibroblasts, and, ultimately, fibrosis. Emerging evidence suggests that iNKT-associated mechanisms contribute to type 1, type 2 and type 3 immune pathways mediating tissue fibrosis, including idiopathic pulmonary fibrosis (IPF). Thus, targeting a pathway upstream of these immune mechanisms, such as the inhibition of iNKT activation, may be important in modulating various fibrotic conditions.

Current Practice in Pediatric Cow's Milk Protein Allergy-Immunological Features and Beyond

Cow's milk protein allergy is one of the most common pediatric food allergies. It poses a significant socioeconomic burden in industrialized countries and has a profound effect on the quality of life of affected individuals and their families. Diverse immunologic pathways can lead to the clinical symptoms of cow's milk protein allergy; some of the pathomechanisms are known in detail, but others need further elucidation. A comprehensive understanding of the development of food allergies and the features of oral tolerance could have the potential to unlock more precise diagnostic tools and novel therapeutic approaches for patients with cow's milk protein allergy.

Where's the Beef? Understanding Allergic Responses to Red Meat in Alpha-Gal Syndrome

Alpha-gal syndrome (AGS) describes a collection of symptoms associated with IgE-mediated hypersensitivity responses to the glycan galactose-alpha-1,3-galactose (alpha-gal). Individuals with AGS develop delayed hypersensitivity reactions, with symptoms occurring >2 h after consuming mammalian ("red") meat and other mammal-derived food products. The mechanisms of pathogenesis driving this paradigm-breaking food allergy are not fully understood. We review the role of tick bites in the development of alpha-gal-specific IgE and highlight innate and adaptive immune cells possibly involved in alpha-gal sensitization. We discuss the impact of alpha-gal glycosylation on digestion and metabolism of alpha-gal glycolipids and glycoproteins, and the implications for basophil and mast cell activation and mediator release that generate allergic symptoms in AGS.

Type 2 Inflammation in Eosinophilic Esophagitis: From Pathophysiology to Therapeutic Targets

Eosinophilic esophagitis (EoE) is a chronic immune-mediated disease of the esophagus characterized clinically by symptoms related to esophageal dysfunction and histologically by eosinophil-predominant inflammation, whose incidence is rising. It significantly affects patients’ quality of life and, if left untreated, results in fibrotic complications. Although broad consensus has been achieved on first-line therapy, a subset of patients remains non-responder to standard therapy. The pathogenesis of EoE is multifactorial and results from the complex, still mostly undefined, interaction between genetics and intrinsic factors, environment, and antigenic stimuli. A deep understanding of the pathophysiology of this disease is pivotal for the development of new therapies. This review provides a comprehensive description of the pathophysiology of EoE, starting from major pathogenic mechanisms (genetics, type 2 inflammation, epithelial barrier dysfunction, gastroesophageal reflux, allergens, infections and microbiota) and subsequently focusing on the single protagonists of type 2 inflammation (involved cells, cytokines, soluble effectors, surface proteins and transcription factors) that could represent present and future therapeutic targets, while summarizing previous therapeutic approaches in literature.

Eosinophilic esophagitis: novel concepts regarding pathogenesis and clinical manifestations

Eosinophilic esophagitis is a chronic disease whose incidence and prevalence are increasing, based on a genetic-driven interaction between environment and immune system. Several gene loci involved in the development of the disease have been identified. A two-step mechanism has been hypothesized: a thymic stromal lymphopoietin-induced allergic sensitization followed by upregulation of CAPN14-related esophageal-specific pathways. Environment seems to have a larger effect than genetic variants. Factors that could play a role are allergens, drugs, colonizing bacteria and possibly Helicobacter Pylori infection. Acting on these modifiable risk factors may be a tool to prevent the disease. EoE is characterized by a typical eosinophilic infiltrate limited to the esophageal epithelium, supported by a Th2-mediated immune response, found in other atopic conditions. The key of the pathogenesis is the disfunction of the epithelial barrier which allow the interaction between allergens and inflammatory cells. Eosinophilic-predominant inflammation leads to the typical wall remodeling, histologically characterized by epithelial and smooth muscle hyperplasia, lamina propria fibrosis and neo-angiogenesis. These alterations find their clinical expression in the pattern of symptoms: dysphagia, food impaction, chest pain, heartburn.

Broad transcriptional response of the human esophageal epithelium to proton pump inhibitors

BACKGROUND

Proton pump inhibitors (PPIs) have been recognized as a primary treatment of eosinophilic esophagitis (EoE), an allergic inflammatory disease of the esophageal mucosa. The mechanisms underlying esophageal epithelial responses to PPIs remain poorly understood.

OBJECTIVE

We hypothesized that PPIs can counteract IL-13-mediated esophageal epithelial responses that are germane for EoE pathogenesis.

METHODS

Transcriptional responses of human esophageal cells to IL-13 and the PPIs omeprazole and esomeprazole were assessed by RT-PCR and RNA sequencing. Cytokine secretion was measured by multiplex analysis and ELISA.

RESULTS

Human esophageal epithelial cells robustly responded to PPI stimulation by inducing a set of 479 core genes common between omeprazole and esomeprazole treatments. The transcriptional response to PPIs was partially mediated through the aryl hydrocarbon receptor signaling pathway, as the aryl hydrocarbon receptor antagonist GNF-351 modified approximately 200 genes, particularly those enriched in metabolic processes and regulation of cell death. PPI treatment reversed approximately 20% of the IL-13 transcriptome. Functional analysis of the PPI-responsive, upregulated genes revealed enrichment in metabolic and oxidation processes, and the unfolded protein response. In contrast, downregulated genes were overrepresented in functional terms related to cell division and cytoskeletal organization, which were also enriched for the genes in the EoE transcriptome reversed by PPIs. Furthermore, PPI treatment decreased the IL-13-induced proliferative response of esophageal epithelial cells.

CONCLUSIONS

These results demonstrate broad effects of PPIs on esophageal epithelium, including their ability to curtail transcriptomic processes involved in cellular proliferation and IL-13-induced responses, and they highlight the importance of AHR signaling in mediating these responses.

Hypersensitivities following allergen antigen recognition by unconventional T cells

Conventional T cells recognise protein-derived antigens in the context of major histocompatibility complex (MHC) class Ia and class II molecules and provide anti-microbial and anti-tumour immunity. Conventional T cells have also been implicated in type IV (also termed delayed-type or T cell-mediated) hypersensitivity reactions in response to protein-derived allergen antigens. In addition to conventional T cells, subsets of unconventional T cells exist, which recognise non-protein antigens in the context of monomorphic MHC class I-like molecules. These include T cells that are restricted to the cluster of differentiation 1 (CD1) family members, known as CD1-restricted T cells, and mucosal-associated invariant T cells (MAIT cells) that are restricted to the MHC-related protein 1 (MR1). Compared with conventional T cells, much less is known about the immune functions of unconventional T cells and their role in hypersensitivities. Here, we review allergen antigen presentation by MHC-I-like molecules, their recognition by unconventional T cells, and the potential role of unconventional T cells in hypersensitivities. We also speculate on possible scenarios of allergen antigen presentation by MHC-I-like molecules to unconventional T cells, the hallmarks of such responses, and the expected frequencies of hypersensitivities within the human population.

Pathogenesis of Eosinophilic Esophagitis: A Comprehensive Review of the Genetic and Molecular Aspects

Eosinophilic esophagitis (EoE) is a relatively new condition described as an allergic-mediated disease of the esophagus. Clinically, it is characterized by dysphagia, food impaction, and reflux-like symptoms. Multiple genome-wide association studies (GWAS) have been conducted to identify genetic loci associated with EoE. The integration of numerous studies investigating the genetic polymorphisms in EoE and the Mendelian diseases associated with EoE are discussed to provide insights into the genetic risk of EoE, notably focusing on CCL26 and CAPN14. We focus on the genetic loci investigated thus far, and their classification according to whether the function near the loci is known. The pathophysiology of EoE is described by separately presenting the known function of each cell and molecule, with the major contributors being eosinophils, Th2 cells, thymic stromal lymphopoietin (TSLP), transforming growth factor (TGF)-β1, and interleukin (IL)-13. This review aims to provide detailed descriptions of the genetics and the comprehensive pathophysiology of EoE.

Recent advances in potential targets for eosinophilic esophagitis treatments

Introduction: Diagnostic and therapeutic strategies in eosinophilic esophagitis (EoE) are constantly evolving. Recently, the improved understanding of EoE pathogenesis has led to identification of a variety of other potential targets that have never been considered before.Areas covered: In September 2019, we performed structured literature searches in Medline and PubMed, Cochrane meta-analyses, and abstracts of international congresses to review new potential therapeutic approaches for EoE.Expert opinion: The advent of omics disciplines has been helping in finding new molecular targets in EoE pathogenesis and may provide future guidance for deep phenotyping of the disease and therefore facilitate the possibility of personalized medicine. Interestingly, these new treatments should be focused on the restoration of epithelial barrier dysfunction, downregulation of specific molecular pathways of eosinophilic inflammation, and finally, prevention of esophageal remodeling. In this review, we highlight the most recent insights in EoE pathogenesis, which open new pathways for developing new therapeutic targets for clinical practice.

The utility of TNF-α, IL-6 and IL-10 in the diagnosis and/or follow-up food allergy

BACKGROUND

Several pro-inflammatory and anti-inflammatory mediators play a role in the immunopathogenesis of food allergy (FA). The aim of this study was to investigate the utility of serum biomarkers like interleukin (IL)-10, TNF-α, and IL-6 in the diagnosis and/or follow-up of FA.

METHODS

Sixty (25 females, 41.6%) newly diagnosed FA patients [IgE mediated (group-1, n=37), non-IgE (group-2, n=23)] with a median age of nine (1-33) months were enrolled. Twenty-four healthy children with a median age of eight (1-36) months constituted the control group (CG). In all the subjects, serum TNF-α, IL-6 and IL-10 levels were evaluated at the time of diagnosis and reassessed four weeks after therapeutic elimination diet (TED).

RESULTS

The mean white blood cell count and median absolute eosinophile count of the CG were significantly lower than group-1 (p values were 0.019 and 0.006, respectively). The mean absolute neutrophile count and the median IL-6 were significantly higher in group-1 when compared with group-2 (p values were 0.005 and 0.032, respectively. Median TNF-α and IL-6 levels were significantly higher in the pre-TED among all patients (p values were 0.005 and 0.018, respectively). In group-1, median TNF-α and IL-6 levels decreased significantly after TED (p values were 0.01 and 0.029, respectively).

CONCLUSIONS

Our findings support the role of inflammation in the pathogenesis of FA. Serum TNF-α and IL-6 levels may be useful markers for follow-up in FA, especially among IgE-mediated FA patients. Evaluation of IL-10 results was not sufficient for an interpretation of clinical tolerance.

Significance of Interleukin (IL)-15 in IgE associated eosinophilic Esophagitis (EoE)

BACKGROUND AND AIM

IgE-mediated immune responses contribute to the pathogenesis of eosinophilic esophagitis (EoE). Interleukin (IL)-4 is a well-established cytokine involved in B cell activation, immunoglobulin (Ig) E production and isotype class switching. Earlier reports indicated that IL-15, B cells and IgE are induced in EoE pathogenesis. Therefore, we hypothesized that induced IL-15 and IgE may have a significant correlation in promoting EoE pathogenesis.

METHODS

Accordingly, we performed ELISA, qPCR, flowcytometric and immunostaining analyses to examine IgE, B cells, eosinophils and mast cells in the esophagus of IL-15 overexpressed mice following EoE induction.

RESULTS

Herein, we show that IL-15 overexpressed mice indeed have induced baseline IL-4, B cells, eosinophils, mast cells and IgE levels in the blood and esophagus. Further, we observed that IL-15 overexpressed mice show induction of IgE, and accumulation of degranulated eosinophils and mast cells in allergen-induced experimental EoE. Notably, despite induced blood IgE, esophageal eosinophilia is not induced in intestinal fatty acid binding protein IL-15 overexpressed gene (Fabpi-IL-15) mice. Fabpi-IL-15 transgenic mice showed IgE in the blood and intestine and intestinal eosinophilia, but no esophageal eosinophilia at baseline and comparable eosinophils in the esophagus of saline and allergen challenged Fabpi-IL-15 mice. Similarly, allergen challenged IL-15 gene-deficient mice show reduced IgE and esophageal eosinophilia in allergen-induced experimental EoE.

CONCLUSIONS

Taken together, we for the first time provide direct evidence that tissue-specific IL-15 induced IgE mediated responses, not systemic IgE is critical in promoting EoE pathogenesis.

Cow's Milk Allergy: Immunomodulation by Dietary Intervention

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

Evaluation of the frequency of invariant natural killer T (iNKT) cells in nasal polyps

Nasal polyps (NP) are associated with inflamed mucosa of unknown etiology. The role of T cells in nasal polyposis is unclear. Invariant natural killer T cells (iNKT) can promote Th2 responses and have been implicated in some types of asthma. As there are shared inflammatory pathways involved in asthma and NPs, we evaluated the frequency of iNKT in 17 patients with NPs, but without asthma. A median of 6% polyp cells were T lymphocytes, of which iNKT were 0 to 2.38% (mean 0.674%). In the matched group (n = 10), iNKT in NPs was significantly higher than PBMCs (1.057% vs 0.155%, P < 0.05). Relative expression of Vα24 to TCR-beta genes in polyps (n = 14) was higher than blood in matched samples (n = 4). The presence of greater proportions of iNKT in NPs than in blood suggests that iNKT may play a role in the pathogenesis of nasal polyposis.

Generation of a Jurkat-based fluorescent reporter cell line to evaluate lipid antigen interaction with the human iNKT cell receptor

Invariant natural killer T (iNKT) cells are a specialized subset of T cells contributing to both, the innate and adaptive immune responses. In contrast to conventional T lymphocytes they recognize lipid antigens. The aim of the project is to establish a novel model system, to study iNKT-TCR - ligand interaction. An iNKT reporter cell line (JE6-1REP-iNKT) was engineered by introducing the human iNKT-TCR into a human leukemic T cell line carrying an NF-κB-driven fluorescent transcriptional reporter construct. Antigen presenting BWSTIM cells expressing human CD1d and CD80 were generated. Reporter induction in JE6-1REP-iNKT cells was assessed by flow cytometry. CRISPR/Cas9 was used for β2M knock out in JE6-1REP-iNKT cells to abrogate CD1d expression and thus excluding antigen self-presentation. Reporter cells were shown to specifically react with iNKT antigens presented via CD1d. Their sensitivity towards α-GalCer was comparable to a murine iNKT hybridoma cell line. In conclusion, we created a novel iNKT reporter platform which, compared to traditional iNKT cell assays, is characterized by a shorter turnaround time and lower costs. It thus facilitates the identification of antigenic structures that drive the activation of iNKT cells in health and disease.

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.

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.

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.

Minimally invasive biomarker studies in eosinophilic esophagitis: A systematic review

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

Food allergen triggers are increased in children with the TSLP risk allele and eosinophilic esophagitis

OBJECTIVES

TSLP has been shown to be associated with eosinophilic esophagitis (EoE). Specifically, children with EoE often have the nucleotides AA or AG instead of GG at the single nucleotide polymorphism position RS3806932. Presently, the phenotypic characteristics in EoE children with the TSLP EoE risk allele are unknown.

METHODS

A retrospective analysis was performed of all children with EoE who had TSLP genotyping at The Children's Hospital of Philadelphia from 2008-2014. EoE food allergen triggers, presence of atopic features, IgE mediated food allergy and skin prick testing results were reviewed. The number and type of EoE food allergen triggers were compared with genotype using chi-square analysis. Primary cell cultures from EoE patients with or without the risk allele were stimulated with ovalbumin and TSLP secretion was measured by ELISA.

RESULTS

Fifty three of 309 patients were found to have no copies of the TSLP risk allele, whereas 256 patients were found to have one or more copies of the risk allele. There was an increase in the number of patients with three or more EoE food allergens among those who were either homozygous or heterozygous for the risk allele compared to those without the risk allele (P < 0.0001). This was independent of their atopic background. Primary cultures from patients homozygous for the risk allele had greater TSLP secretion than those isolated from heterozygous patients.

CONCLUSIONS

The TSLP risk allele is associated with having multiple EoE food allergen triggers. This novel EoE genotypic-phenotypic correlation may guide future treatment for those with the TSLP risk allele.

Pathophysiology of Eosinophilic Esophagitis

Eosinophilic esophagitis is an emerging disease that is distinguished from gastroesophageal reflux disease by the expression of a unique esophageal transcriptome and the interplay of early life environmental factors with distinct genetic susceptibility elements at 5q22 (TSLP) and 2p23 (CAPN14). Rare genetic syndromes have uncovered the contribution of barrier disruption, mediated in part by defective desmosomes and dysregulated transforming growth factor beta production and signaling, to eosinophilic esophagitis pathophysiology. Experimental modeling has defined a cooperative role of activated eosinophils, mast cells, and the cytokines IL-5 and IL-13, mediated by allergic sensitization to multiple foods. Understanding these processes is opening the way to better treatment based on disrupting allergic inflammatory and type 2 cytokine-mediated responses, including anti-cytokine therapeutics and dietary therapy.

Eosinophilic Esophagitis: Pathophysiology and Definition

Eosinophilic esophagitis is an adaptive immune response to patient-specific antigens, mostly foods. Eosinophilic esophagitis is not solely IgE-mediated and is likely characterized by Th2 lymphocytes with an impaired esophageal barrier function. The key cytokines and chemokines are thymic stromal lymphopoeitin, interleukin-13, CCL26/eotaxin-3, and transforming growth factor-β, all involved in eosinophil recruitment and remodeling. Chronic food dysphagia and food impactions, the feared late complications, are related in part to dense subepithelial fibrosis, likely induced by interleukin-13 and transforming growth factor-β.

Elevated expression of activated TH2 cells and milk-specific TH2 cells in milk-induced eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is an allergic inflammatory disease that is triggered by food allergens and characterized by progressive esophageal dysfunction. Esophageal biopsy specimens are characterized by eosinophilia and expression of T_H2 cytokines.

OBJECTIVE

To ascertain whether T_H2 cells can exist in the peripheral blood in patients with milk-induced EoE.

METHODS

Peripheral blood mononuclear cells from 20 children with milk-induced EoE were collected during active EoE (EoE-A) while consuming milk and inactive EoE (EoE-I) while not consuming milk, and 8 healthy patients without EoE were used as controls. The samples were analyzed for T-cell phenotype, including intracellular cytokines before and after incubation with milk antigens and assessed by flow cytometry.

RESULTS

We found a significant increase in CD4⁺ T_H2 cells in the peripheral blood of patients with EoE-A compared with the controls. Furthermore, we observed a significant mean (SD) increase in the activation marker of CD154⁺ T cells (0.17% [0.047^%]) in patients with EoE-A compared with control patients (0.034% [0.007%]) and EoE-I (0.025% [0.008]). These CD4⁺ T cells expressed significantly increase levels of T_H2 cytokines (interleukins 4, 5, and 13) compared with the EoE-I and control groups. CD3⁺CD4⁺CD154⁺IL-5⁺ cells were significantly increased by milk antigens in both milk-induced EoE-A (0.050% [0.008%] to 0.079% [0.017%]) and EoE-I (0.0045% [0.002%] to 0.014% [0.008%]) compared with the controls (0.008% [0.003%] to 0.003% [0.001%]).

CONCLUSION

Our findings indicate that in EoE peripheral T cells have specific activation to milk allergens.

Eosinophilic Esophagitis in Children

PURPOSE OF REVIEW

EoE is a significant cause of gastrointestinal morbidity affecting 1:2000. Patients with EoE typically have multiple atopic comorbidities, and additionally, many patients with EoE can be controlled well with elimination diets. The purpose of this review is to summarize the care of pediatric eosinophilic esophagitis patients.

RECENT FINDINGS

EoE represents a distinct clinical syndrome which is characterized by esophageal dysfunction and eosinophil-predominant inflammation of the esophageal mucosa. Patients with EoE can present with varying symptoms depending on their age; in this review, we review the presenting features of eosinophilic esophagitis in children as well as a diagnostic algorithm for EoE. The mucosal inflammation in EoE is driven by exposure to food antigens in many patients with EoE. Therefore, for the majority of patients, the mainstays of treatment remain food elimination diets or swallowed steroids. This review summarizes the diagnostic approach to eosinophilic esophagitis (EoE) in pediatric patients, focusing on the importance of accurate diagnosis and selection of appropriate therapy.

Mechanisms underlying induction of allergic sensitization by Pru p 3

BACKGROUND

Recently, the nature of the lipid-ligand of Pru p 3, one of the most common plant food allergens in southern Europe, has been identified as a derivative of the alkaloid camptothecin bound to phytosphingosine. However, the origin of its immunological activity is still unknown.

OBJECTIVE

We sought to evaluate the role of the Pru p 3 lipid-ligand in the immunogenic activity of Pru p 3.

METHODS

In vitro cultures of different cell types (monocyte-derived dendritic cells [moDCs], PBMCs [peripheral blood mononuclear cells] and epithelial and iNKT-hybridoma cell lines) have been used to determine the immunological capacity of the ligand, by measuring cell proliferation, maturation markers and cytokine production. To study the capacity of the lipid-ligand to promote sensitization to Pru p 3 in vivo, a mouse model of anaphylaxis to peach has been produced and changes in the humoral and basophil responses have been analysed.

RESULTS

The lipid-ligand of Pru p 3 induced maturation of moDCsc and proliferation of PBMCs. Its immunological activity resided in the phytosphingosine tail of the ligand. The adjuvant activity of the ligand was also confirmed in vivo, where the complex of Pru p 3-ligand induced higher levels of IgE than Pru p 3 alone. The immunological capacity of the Pru p 3 ligand was mediated by CD1d, as maturation of moDCs was inhibited by anti-CD1d antibodies and Pru p 3-ligand co-localized with CD1d on epithelial cells. Finally, Pru p 3-ligand presented by CD1d was able to interact with iNKTs.

CONCLUSIONS AND CLINICAL RELEVANCE

The Pru p 3 lipid-ligand could act as an adjuvant to promote sensitization to Pru p 3, through its recognition by CD1d receptors. This intrinsic adjuvant activity of the accompanying lipid cargo could be a general essential feature of the mechanism underlying the phenomenon of allergenicity.

The Role of Lipids in Development of Allergic Responses

Most allergic diseases are caused by activation of Th2 type immune responses resulting in the production of specific IgE against proteins found in normally harmless substances such as pollen, mites, epithelia or food. Allergenic substances are composed, in addition to proteins, of other compounds such as carbohydrates and lipids. Those lipids are able to promote the development of Th2-type responses associated with allergy. There are lipids found in pollen, milk or insect venom that are specifically recognized by CD1 restricted unconventional T lymphocytes, which can promote allergic reactions. Furthermore, a large number of allergens are proteins containing hydrophobic parts that specifically bind lipids that are capable to favor allergenic immune responses. Also, lipids associated to substances like pollen, dander, epithelia or the bacteria can act on cells of the innate system, including dendritic cells, which in turn lead to the differentiation of Th2-type clones. Finally, lipids may also influence the ability of allergens to be exposed to the immune system within the oral, respiratory or intestinal mucosa where allergic response occurs with great frequency.

Eosinophilic esophagitis phenotypes: Ready for prime time?

Eosinophilic esophagitis (EoE) is one of the most common causes of reflux-like symptoms and feeding problems in children and food impaction and dysphagia in adults with a prevalence of 1:2500. Therapeutic options include diet, use of swallowed corticosteroids, or dilation. In the last several years, recent clinical and translational researches have identified some common and distinctive features, for example, the varying response to diet and medications. As EoE shares some characteristics with both asthma and inflammatory bowel disease, the advances in these fields suggest that various phenotypes may also exist in patients with EoE. Here, we provide a rationale for EoE phenotypes and provide some suggestions for potential phenotypes based on histology, molecular signature, response to therapy or dietary therapy.

Eosinophilic esophagitis: unclear roles of IgE and eosinophils

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the oesophagus. Recognized as a distinct entity only two decades ago, the emergence of the disease along with the availability of new technologies has rapidly opened new research avenues and outlined the main features of the pathogenesis of EoE. Yet, each advance in our understanding of the disease has raised new questions about the previous consensus. Currently, new subsets of the disease challenge our diagnostic criteria. For instance, it was believed that EoE did not respond to proton pump inhibitor (PPI) therapy; however, it has now been shown that a substantial proportion of EoE patients indeed respond to PPIs. In addition, a new subset of patients not even presenting eosinophil infiltrates in the oesophagus has also been described. Moreover, approaches for better understanding the heritability of the disease bring into question the dogma of predominant genetic involvement. Furthermore, the specificity and sensitivity of allergy testing for targeted food avoidance is highly controversial, and the production of specific antibodies in EoE now includes IgG4 in addition to IgE. In conclusion, EoE is perceived as 'a moving target' and the aim of this review was to summarize the current understanding of EoE pathogenesis.

Eosinophilic Esophagitis: A Comprehensive Review

Eosinophilic esophagitis (EoE) is an emerging chronic atopic clinical-pathologic disease with an estimated prevalence of 1/1000 similar to the one of Crohn's diseases. Usually, EoE is firstly suspected due to symptoms that are caused by esophageal dysfunction and/or fibrosis. EoE diagnosis is confirmed if the esophageal biopsy shows at least 15 eosinophils per high power field (eos/hpf) as a peak value in one or more of at least four specimens obtained randomly from the esophagus. Most of the patients affected by EoE have other atopic diseases such as allergic rhinitis, asthma, IgE-mediated food allergies, and/or atopic dermatitis. The local inflammation is a T helper type 2 (Th2) flogosis, which most likely is driven by a mixed IgE and non-IgE-mediated reaction to food and/or environmental allergens. Recently published genetic studies showed also that EoE is associated with single nucleotide polymorphism (SNP) on genes which are important in atopic inflammation such as thymic stromal lymphopoietin (TSLP) located close to the Th2 cytokine cluster (IL-4, IL-5, IL-13) on chromosome 5q22. When the EoE diagnosis is made, it is imperative to control the local eosinophilic inflammation not only to give symptomatic relief to the patient but also to prevent complications such as esophageal stricture and food impaction. EoE is treated like many other atopic diseases with a combination of topical steroids and/or food antigen avoidance.

Eosinophilic disorders of the gastro-intestinal tract: an update

Eosinophilic diseases of the gastrointestinal tract, including eosinophilic esophagitis (EoE) and eosinophilic gastroenteritis (EGE), are rare chronic pathologies of the digestive system, with an immuno-mediated pathogenesis. Recent data suggest that, together with the “classic” IgE-response to allergens, also a delayed hypersensitivity mechanism could be involved in the development of eosinophilic disorders. EoE and EGE were studied only in the latest decades and as a consequence accurate data are not yet available, concerning not only pathogenesis, but also epidemiology, treatment and outcomes. The diagnosis of EoE is centered on endoscopic findings but the certainty is obtained by histological examination from biopsy samples, that has a sensitivity of 100% when based on five samples. The currently available treatments include topical corticosteroids, specific diets and endoscopic treatment. Concerning EGE, three subtypes (mucosal, muscular, and serosal) were identified. The diagnosis is based, as for EoE, on endoscopic and histological assessment, and the treatment includes pharmacological and dietetic approaches. Further studies are warranted in order to better define the etiology and pathogenesis of eosinophilic diseases of the gastrointestinal tract, and thus to develop more appropriate and specific therapies.

Developments in the field of allergy in 2014 through the eyes of Clinical and Experimental Allergy

The pathogenesis of asthma continues to be a major topic of interest to our authors with reviews and original papers on the role of viruses, mechanisms of inflammation, biomarkers, and phenotypes of asthma being major topics. A number of papers described new treatments for asthma focusing on blocking the Th2 response reflecting the fact that two decades of work in this area is finally bearing fruit. The pathogenesis of chronic rhinosinusitis is a growing area of interest, but there has been less on the genetics of airways disease than in previous years possibly reflecting the degree of rigour (and therefore a smaller body of work), with which these sorts of studies are now being undertaken. There continues to be a wide range of papers dealing with mechanisms of allergic disease ranging from clinical-based studies to basic research and the use of in vivo animal models especially mice. As before, mechanisms and new approaches to immunotherapy are common themes. Several were published in the allergens section investigating modification of allergens to increase their effectiveness and reduce the risk of adverse events. Risk factors for allergic disease was a common theme in the epidemiology section and food allergy a common theme in clinical allergy with papers on the development of protocols to induce tolerance and attempts to find biomarkers to distinguish sensitization from allergic disease. This was another exciting year for the editors, and we hope the readers of the journal.

Eosinophilic esophagitis: published evidences for disease subtypes, indications for patient subpopulations, and how to translate patient observations to murine experimental models

Eosinophilic esophagitis (EoE) is a chronic inflammatory disorder of the esophagus and commonly classified as a Th2-type allergy. Major advances in our understanding of the EoE pathophysiology have recently been made, but clinicians struggle with highly unpredictable therapy responses indicative of phenotypic diversity within the patient population. Here, we summarize evidences for the existence of EoE subpopulations based on diverse inflammatory characteristics of the esophageal tissue in EoE. Additionally, clinical characteristics of EoE patients support the concept of disease subtypes. We conclude that clinical and experimental evidences indicate that EoE is an umbrella term for conditions that are unified by esophageal eosinophilia but that several disease subgroups with various inflammatory esophageal patterns and/or different clinical features exist. We further discuss strategies to study the pathophysiologic differences as observed in EoE patients in murine experimental EoE. Going forward, models of EoE that faithfully mimic EoE subentities as defined in humans will be essential because mechanistic studies on triggers which regulate the onset of diverse EoE subpopulations are not feasible in patients. Understanding how and why different EoE phenotypes develop will be a first and fundamental step to establish strategies that integrate individual variations of the EoE pathology into personalized therapy.

Characterizing the inflammatory response in esophageal mucosal biopsies in children with eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an emerging allergic, IgE- and non-IgE (Th2 cell)-mediated disease. There are major gaps in the understanding of the basic mechanisms that drive the persistence of EoE. We investigated whether esophageal biopsies from children with EoE demonstrate an inflammatory response that is distinct from normal controls. We prospectively enrolled 84 patients, of whom 77 were included in our analysis, aged 4-17 years (12.8±3.8 years; 81% males). Five esophageal biopsies were collected from each patient at the time of endoscopy. Intramucosal lymphocytes were isolated, phenotyped and stimulated with phorbol 12-myristate 13-acetate/ionomycin to measure their potential to produce cytokines via flow cytometry. We also performed cytokine arrays on 72-h biopsy culture supernatants. CD8(+) T cells, compared with CD4(+) T cells, synthesized more TNF-α and interferon (IFN)-γ after mitogen stimulation in the EoE-New/Active vs EoE-Remission group (P=0.0098; P=0.02) and controls (P=0.0008; P=0.03). Culture supernatants taken from explant esophageal tissue contained 13 analytes that distinguished EoE-New/Active from EoE-Remission and Controls. Principal component analysis and cluster analysis based on these analytes distinctly separated EoE-New/Active from EoE-Remission and Controls. In summary, we have identified a previously unappreciated role for CD8(+) T lymphocytes with potential to produce TNF-α and IFN-γ in EoE. Our results suggest that CD8(+) T cells have a role in the persistence or progression of EoE. We have also identified a panel of analytes produced by intact esophageal biopsies that differentiates EoE-New/Active from EoE-Remission and controls. Our results suggest that esophageal epithelial cells may have specific immune effector functions in EoE that control the type and amplitude of inflammation.

The Immunologic Mechanisms of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory disease that is triggered by food and/or environmental allergens and is characterized by a clinical and pathologic phenotype of progressive esophageal dysfunction due to tissue inflammation and fibrosis. EoE is suspected in patients with painful swallowing, among other symptoms, and is diagnosed by the presence of 15 or more eosinophils per high-power field in one or more of at least four esophageal biopsy specimens. The prevalence of EoE is increasing and has now reached rates similar to those of other chronic gastrointestinal disorders such as Crohn's disease. In recent years, our understanding of the immunologic mechanisms underlying this condition has grown considerably. Thanks to new genetic, molecular, cellular, animal, and translational studies, we can now postulate a detailed pathway by which exposure to allergens results in a complex and coordinated type 2 inflammatory cascade that, if not intervened upon, can result in pain on swallowing, esophageal strictures, and food impaction. Here, we review the most recent research in this field to synthesize and summarize our current understanding of this complex and important disease.

From genetics to treatment of eosinophilic esophagitis

PURPOSE OF REVIEW

Eosinophilic Esophagitis (EoE) is an emerging chronic atopic disease. Recent advances in understanding its genetic and molecular biology pathogenesis may lead to a better management of the disease

RECENT FINDINGS

EoE is an atopic disease. Most of the patients affected by EoE have other atopic diseases such as allergic rhinitis, asthma, IgE-mediated food allergies and/or atopic dermatitis. The local inflammation is a T helper type 2 (Th2) flogosis, which most likely is driven by a mixed IgE and n-IgE-mediated reaction to food and/or environmental allergens. Epidemiological studies show that EoE is an atopic disease with a strong genetic component. Genetic studies have shown that EoE is associated with single nucleotide polymorphism on genes, which are released by the epithelium and important in atopic inflammation such as thymic stromal lymphopoietin located (TSLP) close to the Th2 cytokine cluster [interleukin (IL)-4, IL-5, IL-13] on chromosome 5q22, Calpain 14, EMSY, and Eotaxin3. When the EoE diagnosis is made, it is imperative to control the local eosinophilic inflammation not only to give symptomatic relief to the patient, but also to prevent complications such as esophageal stricture and food impaction.

SUMMARY

EoE is treated like many other atopic diseases with a combination of topical steroids and/or food antigen avoidance. The new understanding of EoE may lead to more specific and definitive treatments of EoE.

Preferential Secretion of Thymic Stromal Lymphopoietin (TSLP) by Terminally Differentiated Esophageal Epithelial Cells: Relevance to Eosinophilic Esophagitis (EoE)

Eosinophilic esophagitis (EoE) is a chronic Th2 and food antigen-mediated disease characterized by esophageal eosinophilic infiltration. Thymic stromal lymphopoetin (TSLP), an epithelial derived cytokine which bridges innate and Th2-type adaptive immune responses in other allergic conditions, is overexpressed in esophageal biopsies of EoE subjects. However, the triggers of TSLP expression in the esophageal epithelium are unknown. The objective of the current study was to characterize TSLP expression in human esophageal epithelium in EoE in vivo and to determine the role of food antigens upon epithelial TSLP expression in vitro. Using immunohistochemistry (IHC), we localized TSLP in esophageal biopsies of active EoE (≥15 eos/hpf), inactive EoE (<15 eos/hpf) and non-EoE control subjects, and found that TSLP expression was restricted to the differentiated suprabasal layer of the epithelium in actively inflamed EoE biopsies. Consistent with these results in vivo, inducible TSLP protein secretion was higher in CaCl₂ differentiated telomerase-immortalized esophageal epithelial cells (EPC2-hTERT) compared to undifferentiated cells of the basal phenotype, following stimulation with the TLR3 ligand poly(I:C). To determine whether food antigens could directly induce epithelial TSLP secretion, differentiated and undifferentiated primary esophageal epithelial cells from EoE and non-EoE subjects were challenged with food antigens clinically relevant to EoE: Chicken egg ovalbumin (OVA), wheat, and milk proteins beta-lactoglobulin (blg) and beta-casein. Food antigens failed to induce TSLP secretion by undifferentiated cells; in contrast, only OVA induced TSLP secretion in differentiated epithelial cells from both EoE and control cell lines, an effect abolished by budesonide and NF-κb inhibition. Together, our study shows that specific food antigens can trigger innate immune mediated esophageal TSLP secretion, suggesting that esophageal epithelial cells at the barrier surface may play a significant role in the pathogenesis of EoE by regulating TSLP expression.

Mechanisms of Disease of Eosinophilic Esophagitis

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

Wheat allergy: diagnosis and management

Triticum aestivum (bread wheat) is the most widely grown crop worldwide. In genetically predisposed individuals, wheat can cause specific immune responses. A food allergy to wheat is characterized by T helper type 2 activation which can result in immunoglobulin E (IgE) and non-IgE mediated reactions. IgE mediated reactions are immediate, are characterized by the presence of wheat-specific IgE antibodies, and can be life-threatening. Non-IgE mediated reactions are characterized by chronic eosinophilic and lymphocytic infiltration of the gastrointestinal tract. IgE mediated responses to wheat can be related to wheat ingestion (food allergy) or wheat inhalation (respiratory allergy). A food allergy to wheat is more common in children and can be associated with a severe reaction such as anaphylaxis and wheat-dependent, exercise-induced anaphylaxis. An inhalation induced IgE mediated wheat allergy can cause baker’s asthma or rhinitis, which are common occupational diseases in workers who have significant repetitive exposure to wheat flour, such as bakers. Non-IgE mediated food allergy reactions to wheat are mainly eosinophilic esophagitis (EoE) or eosinophilic gastritis (EG), which are both characterized by chronic eosinophilic inflammation. EG is a systemic disease, and is associated with severe inflammation that requires oral steroids to resolve. EoE is a less severe disease, which can lead to complications in feeding intolerance and fibrosis. In both EoE and EG, wheat allergy diagnosis is based on both an elimination diet preceded by a tissue biopsy obtained by esophagogastroduodenoscopy in order to show the effectiveness of the diet. Diagnosis of IgE mediated wheat allergy is based on the medical history, the detection of specific IgE to wheat, and oral food challenges. Currently, the main treatment of a wheat allergy is based on avoidance of wheat altogether. However, in the near future immunotherapy may represent a valid way to treat IgE mediated reactions to wheat.

From the Deep Sea to Everywhere: Environmental Antigens for iNKT Cells

Invariant natural killer T (iNKT) cells are a unique subset of innate T cells that share features with innate NK cells and adaptive memory T cells. The first iNKT cell antigen described was found 1993 in a marine sponge and it took over 10 years for other, bacterial antigens to be described. Given the paucity of known bacterial iNKT cell antigens, it appeared as if iNKT cells play a very specialist role in the protection against few, rare and unusual pathogenic bacteria. However, in the last few years several publications painted a very different picture, suggesting that antigens for iNKT cells are found almost ubiquitous in the environment. These environmental iNKT cell antigens can shape the distribution, phenotype and function of iNKT cells. Here, these recent findings will be reviewed and their implications for the field will be outlined.

Recent research advances in eosinophilic esophagitis

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Eosinophilic esophagitis: From pathophysiology to treatment

Eosinophilic esophagitis (EoE) is a chronic immune disease, characterized by a dense eosinophilic infiltrate in the esophagus, leading to bolus impaction and reflux-like symptoms. Traditionally considered a pediatric disease, the number of adult patients with EoE is continuously increasing, with a relatively higher incidence in western countries. Dysphagia and food impaction represent the main symptoms complained by patients, but gastroesophageal reflux-like symptoms may also be present. Esophageal biopsies are mandatory for the diagnosis of EoE, though clinical manifestations and proton pump inhibitors responsiveness must be taken into consideration. The higher prevalence of EoE in patients suffering from atopic diseases suggests a common background with allergy, however both the etiology and pathophysiology are not completely understood. Elimination diets are considered the first-line therapy in children, but this approach appears less effective in adults patients, who often require steroids; despite medical treatments, EoE is complicated in some cases by esophageal stricture and stenosis, that require additional endoscopic treatments. This review summarizes the evidence on EoE pathophysiology and illustrates the safety and efficacy of the most recent medical and endoscopic treatments.