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

Eosinophilic Esophagitis: A Review for the Primary Care Practitioner

This chapter presents an overview of eosinophilic esophagitis (EoE) for the Primary Care Practitioner (PCP). The focus is on helping PCPs keep it in their differential diagnosis by discussing the spectrum of clinical presentations, how to screen for EoE in at-risk populations and subsequently manage the patient with this condition. The authors review epidemiology, risk factors and associated conditions, pathology, clinical presentation, diagnosis, and management options.

Triggers for eosinophilic esophagitis (EoE): The intersection of food allergy and EoE

Eosinophilic esophagitis and IgE-mediated food allergy are both food-triggered diseases that are increasing in prevalence. They share many clinical links, including significant comorbidity and similar food triggers, and as atopic diseases, they likely share upstream mechanisms related to barrier function and signals leading to TH2 skewing. In this review, we focus on links between eosinophilic esophagitis and IgE-mediated food allergy with an emphasis on what insights may be derived from overlapping food triggers and immune phenotypes. Through further investigation of these connections, we may be able to better understand not only IgE-mediated food allergy and eosinophilic esophagitis but also general atopic response to food proteins and evolution of allergic response to food.

Outcomes of Serum Food-Specific Immunoglobulin G 4 to Guide Elimination Diet in Patients With Eosinophilic Esophagitis

INTRODUCTION

Eosinophilic esophagitis (EoE) is associated with atopy; however, recent studies have identified an association with food-specific immunoglobulin G 4 (FS-IgG 4 ) rather than immunoglobulin E antibodies. This study aimed to evaluate the role of serum FS-IgG 4 in guiding an elimination diet and its outcomes.

METHODS

Patients with and without EoE were enrolled in a prospective, controlled, single tertiary center trial. Serum FS-IgG 4 titers, esophageal eosinophil counts, and dysphagia symptom questionnaire scores were assessed, and participants with elevated FS-IgG 4 (ImmunoCAP, cutoff of 10 mgA/L) commenced 6-week targeted elimination diet. Repeat serum FS-IgG 4 and endoscopic and histologic examination were performed at 6-week follow-up.

RESULTS

Twenty-two patients with active EoE and 13 controls were recruited. Serum FS-IgG 4 to milk, wheat, soy, eggs, and nuts was significantly higher in EoE ( P = 0.0002, P = 0.002, P = 0.003, P = 0.012, and P < 0.001, respectively). Elevated serum FS-IgG 4 to 1 or more food groups (median 2) was identified in 21/22 (95.4%) patients with EoE; 20/21 underwent 6-week dietary elimination. Median reductions in dysphagia symptom questionnaire score and EoE endoscopic reference score after elimination were 8 ( P = 0.0007) and 1 ( P = 0.002), respectively. Nine (45%) patients had histological remission (<15 eosinophils per high-power field). Fall in median esophageal eosinophil count was not statistically significant (50 vs 23; P = 0.068). Serum FS-IgG 4 did not decline by 6-week follow-up.

DISCUSSION

Serum FS-IgG 4 to milk, wheat, soy, egg, and nuts was present at higher levels in EoE, with targeted elimination resulting in 45% histologic remission rate. Serum FS-IgG 4 has potential as a noninvasive biomarker in EoE. When successful, FS-IgG 4 -led elimination diet can negate need for medications and be viewed more favorably by patients because of its smaller endoscopic burden compared with empirical elimination diets.

The 1st EoETALY Consensus on the Diagnosis and Management of Eosinophilic Esophagitis - Definition, Clinical Presentation and Diagnosis

Eosinophilic esophagitis (EoE) is a chronic type 2-mediated inflammatory disease of the esophagus that represents the most common eosinophilic gastrointestinal disease. Experts in the field of EoE across Italy (i.e., EoETALY Consensus Group) including gastroenterologists, endoscopists, allergologists/immunologists, and paediatricians conducted a Delphi process to develop updated consensus statements for the management of patients with EoE and update the previous position paper of the Italian Society of Gastroenterology (SIGE) in light of recent evidence. Grading of the strength and quality of the evidence of the recommendations was performed using accepted GRADE criteria. The guideline is divided in two documents: Part 1 includes three chapters, namely 1) definition, epidemiology, and pathogenesis; 2) clinical presentation and natural history, and 3) diagnosis, while Part 2 includes two chapters: 4) treatment and 5) monitoring and follow-up. This document has received the endorsement of three Italian national societies including the SIGE, the Italian Society of Neurogastroenterology and Motility (SINGEM), and the Italian Society of Allergology, Asthma, and Clinical Immunology (SIAAIC). With regards to patients' involvement, these guidelines involved the contribution of members of ESEO Italia, the Italian Association of Families Against EoE.

Efficacy and Safety of Monoclonal Antibodies for the Treatment of Eosinophilic Esophagitis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND AND AIMS

Monoclonal antibodies (MAbs) have clinical benefits for treating several atopic diseases. However, consensus on its use for eosinophilic esophagitis (EoE) is lacking. The present meta-analysis aimed to compare the efficacy and safety of MAbs versus placebo for treating EoE.

METHODS

We searched PubMed, Embase, and Cochrane Library for randomized controlled trials (RCTs). The primary outcomes were changes in peak esophageal eosinophils count/high power field (HPF) and mean esophageal eosinophils count/HPF. The secondary outcomes were changes in the EoE-Histology Scoring System (EoE-HSS), Endoscopic Reference Score (EREFS), dysphagia score, and adverse events (AEs). We compared binary outcomes using risk ratio (RR) and continuous outcomes using mean difference (MD) or standardized mean difference (SMD), with 95% confidence interval (CI). Considering the diversity of mechanistic properties of MAbs, a pre-specified subgroup analysis by MAb mechanism of action was performed for all outcomes, provided that at least two studies were in each subgroup. Heterogeneity was assessed using Cochran's Q test and I2 statistics.

RESULTS

6 RCTs were included (533 patients). Compared to placebo, MAbs led to a significant reduction in peak esophageal eosinophils count/HPF (MD -0.78; CI 95% -0.87, -0.6801) and mean esophageal eosinophils count/HPF (SMD -0.79; CI 95% -1.5, -0.08). Moreover, MAbs significantly reduced EoE-HSS scores (grade score: SMD -9.31; 95% CI -13.95, -4.6701; stage score: SMD -10.18; 95% CI -15.06, -5.31), EREFS (SMD -5.95; CI 95% -9.19, -2.71) and dysphagia score (SMD -1.79; CI 95% -3.36, -0.23) without increasing AEs compared to placebo. Among those MAbs whose mechanism of action includes the blockage of the receptor for IL-13 (Dupilumab, QAX576, and RPC4046), the scores of EoE-HSS grade, EoE-HSS stage, EREFS, and dysphagia were significantly reduced, and they presented a similar risk of overall and serious AEs compared to placebo.

CONCLUSION

MAbs seem effective and safe in reducing esophageal eosinophil infiltrate, EoE-HSS score, EREFS score, and dysphagia symptoms in patients with EoE. However, further evidence is needed to establish its place in EoE management.

Dietary Management of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic immune-mediated food allergy-driven disease characterized by eosinophilic inflammation of the esophagus leading to symptoms of esophageal dysfunction. Prior studies have supported the key role of food allergen exposure as the main driver behind the etiopathogenesis showing that removal of food antigens can result in disease remission in both children and adults. These landmark studies serve as the basis for the rising interest and evolution of dietary therapy in EoE. This article will focus on the rationale for dietary therapy in EoE and provide helpful tools for the implementation of dietary therapy in practice.

Epithelial overexpression of IL-33 induces eosinophilic esophagitis dependent on IL-13

BACKGROUND

Eosinophilic esophagitis (EoE) is an increasingly common inflammatory condition of the esophagus; however, the underlying immunologic mechanisms remain poorly understood. The epithelium-derived cytokine IL-33 is associated with type 2 immune responses and elevated in esophageal biopsy specimens from patients with EoE.

OBJECTIVE

We hypothesized that overexpression of IL-33 by the esophageal epithelium would promote the immunopathology of EoE.

METHODS

We evaluated the functional consequences of esophageal epithelial overexpression of a secreted and active form of IL-33 in a novel transgenic mouse, EoE33. EoE33 mice were analyzed for clinical and immunologic phenotypes. Esophageal contractility was assessed. Epithelial cytokine responses were analyzed in three-dimensional organoids. EoE33 phenotypes were further characterized in ST2-/-, eosinophil-deficient, and IL-13-/- mice. Finally, EoE33 mice were treated with dexamethasone.

RESULTS

EoE33 mice displayed ST2-dependent, EoE-like pathology and failed to thrive. Esophageal tissue remodeling and inflammation included basal zone hyperplasia, eosinophilia, mast cells, and TH2 cells. Marked increases in levels of type 2 cytokines, including IL-13, and molecules associated with immune responses and tissue remodeling were observed. Esophageal organoids suggested reactive epithelial changes. Genetic deletion of IL-13 in EoE33 mice abrogated pathologic changes in vivo. EoE33 mice were responsive to steroids.

CONCLUSIONS

IL-33 overexpression by the esophageal epithelium generated immunopathology and clinical phenotypes resembling human EoE. IL-33 may play a pivotal role in the etiology of EoE by activating the IL-13 pathway. EoE33 mice are a robust experimental platform for mechanistic investigation and translational discovery.

Pathophysiology of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic, progressive immune-mediated disease associated with antigen-driven type 2 inflammation and symptoms of esophageal dysfunction. Research over the last 2 decades has dramatically furthered our understanding of the complex interplay between genetics, environmental exposures, and cellular and molecular interactions involved in EoE. This review provides an overview of our current understanding of EoE pathogenesis.

An esophagus cell atlas reveals dynamic rewiring during active eosinophilic esophagitis and remission

Coordinated cell interactions within the esophagus maintain homeostasis, and disruption can lead to eosinophilic esophagitis (EoE), a chronic inflammatory disease with poorly understood pathogenesis. We profile 421,312 individual cells from the esophageal mucosa of 7 healthy and 15 EoE participants, revealing 60 cell subsets and functional alterations in cell states, compositions, and interactions that highlight previously unclear features of EoE. Active disease displays enrichment of ALOX15+ macrophages, PRDM16+ dendritic cells expressing the EoE risk gene ATP10A, and cycling mast cells, with concomitant reduction of TH17 cells. Ligand-receptor expression uncovers eosinophil recruitment programs, increased fibroblast interactions in disease, and IL-9+IL-4+IL-13+ TH2 and endothelial cells as potential mast cell interactors. Resolution of inflammation-associated signatures includes mast and CD4+ TRM cell contraction and cell type-specific downregulation of eosinophil chemoattractant, growth, and survival factors. These cellular alterations in EoE and remission advance our understanding of eosinophilic inflammation and opportunities for therapeutic intervention.

Expression of Immunoglobulin G4 in Eosinophilic Esophagitis

Background: Eosinophilic esophagitis (EoE) is a disease that has been subcategorized into two endoscopic phenotypes: inflammatory and fibrostenotic. Moreover, studies have shown a link between EoE and immunoglobulin G4 (IgG4), a subclass of the immunoglobulin G (IgG) antibody. In this study, we aimed to evaluate the relationship between histologic IgG4 expression and endoscopic phenotypes in patients with EoE. Methods: This case-control study included patients diagnosed with EoE (n = 19) and patients with non-obstructive dysphagia without abnormal findings as controls (NOD; n = 12). The EoE group was further divided into three subgroups based on endoscopic phenotype: inflammatory, fibrostenotic, or combined. Retrospective examination of endoscopic findings and pathological slides was performed to analyze IgG4 staining. Results: Histological analysis revealed a significant difference in IgG4 cell count (15.00 vs. 0.58, p = 0.003) and eosinophil cell count (84.67 vs. 0.08, p < 0.001) between the EoE and NOD groups. Symptom manifestation and blood test results were similar across all three endoscopic EoE phenotypes. However, histological analysis revealed a significant difference in IgG4 cell count between the inflammatory, fibrostenotic, and combined phenotypes (4.13 vs. 17.6 vs. 59.7, p = 0.030). Conclusions: IgG4 expression was higher in EoE patients than in those with NOD, the highest being in the combined phenotype subgroup. These findings emphasize the important role of endoscopic and histological examination in diagnosing EoE and the need for further research in this area.

Eosinophilic Esophagitis: Clinical Pearls for Primary Care Providers and Gastroenterologists

Eosinophilic esophagitis (EoE) is a chronic and progressive immune-mediated esophageal disorder. Given its increasing incidence, it is now a leading cause of dysphagia and food impaction in the United States. Eosinophilic esophagitis is most common in adult White men and has a high concurrence rate with other atopic conditions like allergic rhinitis, bronchial asthma, and eczema. The initial presentation includes symptoms of esophageal dysfunction, classically solid-food dysphagia. Without treatment, inflammation can progress to fibrosis with the formation of strictures, leading to complications such as food impaction. It is a clinicopathologic disease requiring compatible clinical symptoms and histologic evidence of eosinophil-predominant inflammation of the esophageal epithelium with more than 15 eosinophils per high-power field. The mainstay of management includes the 3 d's (diet, drugs, dilation): dietary modifications to eliminate trigger food groups; medications including proton pump inhibitors, swallowed topical glucocorticoids, and dupilumab; and esophageal dilation to manage strictures. Various elimination diets have been found to be effective, including 1-food, 2-food, 4-food, and 6-food elimination diets. Dupilumab, a humanized monoclonal antibody that regulates interleukin 4 and 13 signaling pathways, has shown promising results in clinical trials and was approved by the Food and Drug Administration in 2022 for use in EoE. Symptom alleviation, although important, is not the sole end point of treatment in EoE as persistent inflammation, even in the absence of symptoms, can lead to esophageal fibrosis and stricture formation over time. The chronic nature and high recurrence rates of EoE warrant maintenance therapy in patients with EoE after initial remission is achieved.

Evolving strategies: Enhancements in managing eosinophilic esophagitis in pediatric patients

Eosinophilic esophagitis is a newly recognized disease first described about 50 years ago. The definition, diagnosis, and management have evolved with new published consensus guidelines and newly approved treatment available to pediatricians, enabling a better understanding of this disease and more targeted treatment for patients. We describe the definition, presentation, and diagnosis of eosinophilic esophagitis including management, challenges, and future directions in children. The definition, diagnosis, and management of eosinophilic esophagitis have evolved over the last 50 years. Consensus guidelines and newly approved biologic treatment have enabled pediatricians to better understand this disease and allow for more targeted treatment for patients. We describe the definition, presentation, diagnosis, management, and treatment in addition to the challenges and future directions of eosinophilic esophagitis management in children.

IgG4 autoantibodies and autoantigens in the context of IgG4-autoimmune disease and IgG4-related disease

Immunoglobulins are an essential part of the humoral immune response. IgG4 antibodies are the least prevalent subclass and have unique structural and functional properties. In this review, we discuss IgG4 class switch and B cell production. We review the importance of IgG4 antibodies in the context of allergic responses, helminth infections and malignancy. We discuss their anti-inflammatory and tolerogenic effects in allergen-specific immunotherapy, and ability to evade the immune system in parasitic infection and tumour cells. We then focus on the role of IgG4 autoantibodies and autoantigens in IgG4-autoimmune diseases and IgG4-related disease, highlighting important parallels and differences between them. In IgG4-autoimmune diseases, pathogenesis is based on a direct role of IgG4 antibodies binding to self-antigens and disturbing homeostasis. In IgG4-related disease, where affected organs are infiltrated with IgG4-expressing plasma cells, IgG4 antibodies may also directly target a number of self-antigens or be overexpressed as an epiphenomenon of the disease. These antigen-driven processes require critical T and B cell interaction. Lastly, we explore the current gaps in our knowledge and how these may be addressed.

Food-specific IgG4-guided diet elimination improves allergy symptoms in children

Allergic diseases in children are major public health concerns due to their widespread and rising prevalence. Food-specific immunoglobulin G4(FS-IgG4) has been detected in patients with allergic diseases, but its clinical significance is still debated. In the present study, 407 children with allergic diseases were recruited and categorized into three groups according to the different systems involved: the respiratory system group, the skin system group, and a multiple system group, with the collection of clinical symptoms and serum antibodies, including total immunoglobulin E (IgE), house dust mite (HDM) IgE, food-specific IgE (FS-IgE), and FS-IgG4. Part of these patients were followed up with the intervention of FS-IgG4-guided diet elimination with or without add-on probiotics supplement. The analysis at baseline revealed distinct serum levels of different antibodies. The positive rate of FS-IgG4 in all groups was more than 80%, and the proportion of total IgE and FS-IgG4 both positive in the multi-system group was the highest (p=0.039). Egg and milk were the foods with the highest positive rate of FS-IgG4 in all groups. After diet elimination for more than 3 months, serum FS-IgG4 in children significantly decreased (P<0.05) along with the improvement of clinical symptoms, regardless of the add-on of probiotics. However, the intervention did not impact the serum levels of total IgE, FS-IgE, and HDM IgE. There was no further decrease of serum FS-IgG4 level in children followed up for more than 1 year, which may be related to noncompliance with diet elimination. Multivariate regression analysis revealed that the decline of serum FS-IgG4 was an independent predictable factor for the improvement of clinical symptoms (adjusted OR:1.412,95%CI 1.017-1.96, p=0.039). The add-on of probiotics showed less efficiency in reducing the FS-IgG4 level in more patients with relief of clinical symptoms. Our results confirmed the correlation between FS-IgG4 and allergic diseases, and the decreased FS-IgG4 could be a useful predictor for the improvement of allergic symptoms. FS-IgG4-guided diet elimination is an efficient treatment for allergic diseases. Our study adds solid data to the clinical significance of FS-IgG4 in allergic diseases.

Review article: Emerging insights into the epidemiology, pathophysiology, diagnostic and therapeutic aspects of eosinophilic oesophagitis and other eosinophilic gastrointestinal diseases

BACKGROUND

Eosinophilic gastrointestinal diseases (EGIDs) are chronic, immune-mediated disorders characterised clinically by gastrointestinal symptoms and histologically by a pathologic increase in eosinophil-predominant inflammation in the gastrointestinal tract, in the absence of secondary causes of eosinophilia.

AIMS

To highlight emerging insights and research efforts into the epidemiology, pathophysiology, diagnostic and therapeutic aspects of eosinophilic oesophagitis (EoE) and non-EoE EGIDs, and discuss key remaining knowledge gaps.

METHODS

We selected and reviewed original research, retrospective studies, case series, randomised controlled trials, and meta-analyses.

RESULTS

Standardised nomenclature classifies EGIDs as EoE, eosinophilic gastritis (EoG), eosinophilic enteritis (EoN), and eosinophilic colitis (EoC). Incidence and prevalence of EoE are rising, emphasising the need to better understand how environmental risk factors and genetic features interact. Advances in understanding EoE pathophysiology have led to clinical trials of targeted therapy and the approval (in the United States) of dupilumab for EoE. Several therapies that are under investigation hope to satisfy both histologic and clinical targets. For non-EoE EGIDs, efforts are focused on better defining clinical and histopathologic disease determinants and natural history, as well as establishing new therapies.

CONCLUSIONS

Unmet needs for research are dramatically different for EoE and non-EoE EGIDs. In EoE, non-invasive diagnostic tests, clinicopathologic models that determine the risk of disease progression and therapeutic failure, and novel biologic therapies are emerging. In contrast, in non-EoE EGIDs, epidemiologic trends, diagnostic histopathologic thresholds, and natural history models are still developing for these more rare disorders.

Eosinophilic esophagitis is associated with increased risk of later inflammatory bowel disease in a nationwide Swedish population cohort

BACKGROUND

Earlier studies on the possible association between eosinophilic esophagitis (EoE) and inflammatory bowel disease (IBD) have been contradictory.

METHODS

Patients with biopsy-verified EoE diagnosed between 1990 and 2017 in Sweden (n = 1587) were age- and sex-matched with up to five general population reference individuals (n = 7808). EoE was defined using pathology reports from all 28 pathology centers in Sweden (the ESPRESSO study). Multivariate Cox regression then estimated hazard ratios for future IBD. IBD was defined based on the international classification of disease codes and histopathology codes. In secondary analyses, sibling comparators were used to further reduce potential familial confounding. Additionally, we performed logistic regression examining earlier IBD in EoE.

RESULTS

During follow-up until 2020, 16 (0.01%) EoE patients and 21 (0.003%) general population reference individuals diagnosed with IBD, corresponding to a 3.5-fold increased risk of future IBD (aHR = 3.56; 95% CI 1.79-7.11). EoE was linked to Crohn's disease (aHR = 3.39 [95% CI 1.02-9.60]) but not to ulcerative colitis (aHR = 1.37; 95% CI 0.38-4.86). Compared to their siblings, patients with EoE were at a 2.48-fold increased risk of IBD (aHR = 2.48; 95% CI 0.92-6.70). Earlier IBD was 15 times more likely in EoE patients than in matched reference individuals (odds ratio, 15.39; 95% CI 7.68-33.59).

CONCLUSION

In this nationwide cohort study, EoE was associated with a 3.5-fold increased risk of later IBD diagnosis. This risk increase may be due to shared genetic or early environmental risk factors, but also surveillance bias could play a role.

The New Therapeutic Frontiers in the Treatment of Eosinophilic Esophagitis: Biological Drugs

Eosinophilic esophagitis (EoE) is a multifaceted disease characterized by a wide heterogeneity of clinical manifestations, endoscopic and histopathologic patterns, and responsiveness to therapy. From the perspective of an effective approach to the patient, the different inflammatory mechanisms involved in the pathogenesis of EoE and biologics, in particular monoclonal antibodies (mAbs), targeting these pathways are needed. Currently, the most relevant is dupilumab, which interferes with both interleukin (IL)-4 and IL-13 pathways by binding IL-4 receptor α, and is the only mAb approved by the European Medicine Agency and US Food and Drug Administration for the treatment of EoE. Other mAbs investigated include mepolizumab, reslizumab, and benralizumab (interfering with IL-5 axis), cendakimab and dectrekumab (anti-IL-13s), tezepelumab (anti-TSLP), lirentelimab (anti-SIGLEG-8), and many others. Despite the undeniable economic impact of biologic therapies, in the near future, there will be room for further reflection about the opportunity to prescribe biologic agents, not only as a last-line therapy in selected cases such as patients with comorbidities involving common pathways. Although recent findings are very encouraging, the road to permanent success in the treatment of EoE is still long, and further studies are needed to determine the long-term effects of mAbs and to discover new potential targets.

Cow's Milk: A Benefit for Human Health? Omics Tools and Precision Nutrition for Lactose Intolerance Management

Cow's milk (CM) is a healthy food consumed worldwide by individuals of all ages. Unfortunately, "lactase-deficient" individuals cannot digest milk's main carbohydrate, lactose, depriving themselves of highly beneficial milk proteins like casein, lactoalbumin, and lactoglobulin due to lactose intolerance (LI), while other individuals develop allergies specifically against these proteins (CMPA). The management of these conditions differs, and an inappropriate diagnosis or treatment may have significant implications for the patients, especially if they are infants or very young children, resulting in unnecessary dietary restrictions or avoidable adverse reactions. Omics technologies play a pivotal role in elucidating the intricate interactions between nutrients and the human body, spanning from genetic factors to the microbiota profile and metabolites. This comprehensive approach enables the precise delineation and identification of distinct cohorts of individuals with specific dietary requirements, so that tailored nutrition strategies can be developed. This is what is called personalized nutrition or precision nutrition (PN), the area of nutrition that focuses on the effects of nutrients on the genome, proteome, and metabolome, promoting well-being and health, preventing diseases, reducing chronic disease incidence, and increasing life expectancy. Here, we report the opinion of the scientific community proposing to replace the "one size fits all" approach with tailor-made nutrition programs, designed by integrating nutrigenomic data together with clinical parameters and microbiota profiles, taking into account the individual lactose tolerance threshold and needs in terms of specific nutrients intake. This customized approach could help LI patients to improve their quality of life, overcoming depression or anxiety often resulting from the individual perception of this condition as different from a normal state.

Fibrous Remodeling in Eosinophilic Esophagitis: Clinical Facts and Pathophysiological Uncertainties

Eosinophilic esophagitis (EoE) is a chronic, progressive, type 2 inflammatory disease with increasing global prevalence. An eosinophil-predominant inflammation that permeates the epithelium and deeper esophageal layers characterizes the disease. Several cytokines, mainly derived from inflammatory T-helper 2 (Th2) cells and epithelial cells, are involved in perpetuating inflammatory responses by increasing surface permeability and promoting tissue remodeling characterized by epithelial-mesenchymal transition (EMT) and collagen deposition. This leads to esophageal strictures and narrow caliber esophagi, which are proportional a patient's age and untreated disease length. Pathophysiological mechanisms leading to EoE have been described in recent years, and transforming growth factor beta (TGF)-beta have been involved in fibrotic phenomena in EoE. However, evidence on the dependence of these phenomena on TGF-beta is scarce and contradictory. This review provides state-of-the art knowledge on intimate mechanisms of esophageal fibrosis in EoE and its clinical consequences.

Eosinophils-from cradle to grave: An EAACI task force paper on new molecular insights and clinical functions of eosinophils and the clinical effects of targeted eosinophil depletion

Over the past years, eosinophils have become a focus of scientific interest, especially in the context of their recently uncovered functions (e.g. antiviral, anti-inflammatory, regulatory). These versatile cells display both beneficial and detrimental activities under various physiological and pathological conditions. Eosinophils are involved in the pathogenesis of many diseases which can be classified into primary (clonal) and secondary (reactive) disorders and idiopathic (hyper)eosinophilic syndromes. Depending on the biological specimen, the eosinophil count in different body compartments may serve as a biomarker reflecting the underlying pathophysiology and/or activity of distinct diseases and as a therapy-driving (predictive) and monitoring tool. Personalized selection of an appropriate therapeutic strategy directly or indirectly targeting the increased number and/or activity of eosinophils should be based on the understanding of eosinophil homeostasis including their interactions with other immune and non-immune cells within different body compartments. Hence, restoring as well as maintaining homeostasis within an individual's eosinophil pool is a goal of both specific and non-specific eosinophil-targeting therapies. Despite the overall favourable safety profile of the currently available anti-eosinophil biologics, the effect of eosinophil depletion should be monitored from the perspective of possible unwanted consequences.

Immunoglobulin G4 in eosinophilic esophagitis: Immune complex formation and correlation with disease activity

BACKGROUND

Recent studies have shown deposition of immunoglobulin G4 (IgG4) and food proteins in the esophageal mucosa of eosinophilic esophagitis (EoE) patients. Our aims were to assess whether co-localization of IgG4 and major cow's milk proteins (CMPs) was associated with EoE disease activity and to investigate the proteins enriched in proximity to IgG4 deposits.

METHODS

This study included adult subjects with EoE (n = 13) and non-EoE controls (n = 5). Esophageal biopsies were immunofluorescence stained for IgG4 and CMPs. Co-localization in paired samples from active disease and remission was assessed and compared to controls. The proteome surrounding IgG4 deposits was evaluated by the novel technique, AutoSTOMP. IgG4-food protein interactions were confirmed with co-immunoprecipitation and mass spectrometry.

RESULTS

IgG4-CMP co-localization was higher in the active EoE group compared to paired remission samples (Bos d 4, p = .02; Bos d 5, p = .002; Bos d 8, p = .002). Co-localization was also significantly higher in the active EoE group compared to non-EoE controls (Bos d 4, p = .0013; Bos d 5, p = .0007; Bos d 8, p = .0013). AutoSTOMP identified eosinophil-derived proteins (PRG 2 and 3, EPX, RNASE3) and calpain-14 in IgG4-enriched areas. Co-immunoprecipitation and mass spectrometry confirmed IgG4 binding to multiple food allergens.

CONCLUSION

These findings further contribute to the understanding of the interaction of IgG4 with food antigens as it relates to EoE disease activity. These data strongly suggest the immune complex formation of IgG4 and major cow's milk proteins. These immune complexes may have a potential role in the pathophysiology of EoE by contributing to eosinophil activation and disease progression.

Changes in mucosal IgG4+- and IL-10+-cell frequencies in adults with eosinophilic esophagitis on a two-food elimination diet

Eosinophilic esophagitis (EoE) is increasingly diagnosed in patients with dysphagia. Type-2 immunity can induce EoE histopathology via non-IgE-dependent mechanisms, possibly involving IgG4 and IL-10. To elucidate the contribution of this response to EoE pathogenesis, we examined its association with clinical and histologic endpoints in adult EoE patients given a two-food elimination diet. IgG4- and IL-10-expressing cells were counted in esophageal biopsies and serum food-specific IgG4 measured at baseline and follow-up. Variables were correlated with histologic measures of disease activity. Patients exhibited significant reduction in esophageal eosinophilia and overall histology. A significant decrease in IL-10+-cell frequencies correlated with histologic changes. In contrast, a decline in serum and esophageal IgG4, while substantial, did not correlate with IL-10+-cell frequencies or histologic parameters. These results suggest a critical role of IL-10 in EoE pathogenesis. Conversely, IgG4 expression, while reflecting exposure to food antigens, is not obviously related to EoE histopathology or IL-10 expression.

The unique properties of IgG4 and its roles in health and disease

IgG4 is the least abundant subclass of IgG in human serum and has unique functional features. IgG4 is largely unable to activate antibody-dependent immune effector responses and, furthermore, undergoes Fab (fragment antigen binding)-arm exchange, rendering it bispecific for antigen binding and functionally monovalent. These properties of IgG4 have a blocking effect, either on the immune response or on the target protein of IgG4. In this Review, we discuss the unique structural characteristics of IgG4 and how these contribute to its roles in health and disease. We highlight how, depending on the setting, IgG4 responses can be beneficial (for example, in responses to allergens or parasites) or detrimental (for example, in autoimmune diseases, in antitumour responses and in anti-biologic responses). The development of novel models for studying IgG4 (patho)physiology and understanding how IgG4 responses are regulated could offer insights into novel treatment strategies for these IgG4-associated disease settings.

Current and Novel Therapies for Eosinophilic Gastrointestinal Diseases

Eosinophilic gastrointestinal diseases (EGIDs) are an emerging group of pathological entities characterized by an eosinophil-predominant infiltration of different tracts of the gut in the absence of secondary causes of eosinophilia. According to the specific tract of the gut involved, EGIDs can be classified into eosinophilic esophagitis (EoE), eosinophilic gastritis (EoG), eosinophilic enteritis (EoN), and eosinophilic colitis (EoC). The epidemiology of EGIDs is evolving rapidly. EoE, once considered a rare disease, now has an incidence and prevalence of 7.7 new cases per 100,000 inhabitants per years and 34.4 cases per 100,000 inhabitants per year, respectively. Fewer data are available regarding non-EoE EGIDs, whose prevalence are estimated to range between 2.1 and 17.6 in 100,000 individuals, depending on age, sex, and ethnicity. Diagnosis requires the presence of suggestive symptoms, endoscopic biopsies showing abnormal values of eosinophils infiltrating the gut, and exclusion of secondary causes of eosinophilia. EoE typically presents with dysphagia and episodes of food bolus impactions, while EoG, EoN, and EoC may all present with abdominal pain and diarrhea, with or without other non-specific symptoms. In addition, although different EGIDs are currently classified as different entities, there may be overlap between different diseases in the same patient. Despite EGIDs being relatively novel pathological entities, the research on possible treatments is rapidly growing. In this regard, several randomized controlled trials are currently ongoing to investigate novel molecules, including ad-hoc steroid formulations, immunosuppressants, and mostly monoclonal antibodies that target the specific molecular mediators of EGIDs. This narrative review provides an up-to-date overview of available and investigational drugs for different EGIDs.

Mast cells disrupt the function of the esophageal epithelial barrier

Mast cells (MCs) accumulate in the epithelium of patients with eosinophilic esophagitis (EoE), an inflammatory disorder characterized by extensive esophageal eosinophilic infiltration. Esophageal barrier dysfunction plays an important role in the pathophysiology of EoE. We hypothesized that MCs contribute to the observed impaired esophageal epithelial barrier. Herein, we demonstrate that coculture of differentiated esophageal epithelial cells with immunoglobulin E-activated MCs significanly decreased epithelial resistance by 30% and increased permeability by 22% compared with non-activated MCs. These changes were associated with decreased messenger RNA expression of barrier proteins filaggrin, desmoglein-1 and involucrin, and antiprotease serine peptidase inhibitor kazal type 7. Using targeted proteomics, we detected various cytokines in coculture supernatants, most notably granulocyte-macrophage colony-stimulating factor and oncostatin M (OSM). OSM expression was increased by 12-fold in active EoE and associated with MC marker genes. Furthermore, OSM receptor-expressing esophageal epithelial cells were found in the esophageal tissue of patients with EoE, suggesting that the epithelial cells may respond to OSM. Stimulation of esophageal epithelial cells with OSM resulted in a dose-dependent decrease in barrier function and expression of filaggrin and desmoglein-1 and an increase in protease calpain-14. Taken together, these data suggest a role for MCs in decreasing esophageal epithelial barrier function in EoE, which may in part be mediated by OSM.

Food-specific IgA levels in esophageal biopsies are not sufficiently high to predict food triggers in eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is an immune-mediated disease, characterized by Th2-type inflammation linked to specific foods. No currently available allergy tests reliably identify food triggers in EoE, leading to empiric dietary elimination strategies. Recently, milk- and wheat-specific IgA in esophageal brushings were linked to clinical food triggers. In this study, we aimed to determine whether food-specific IgA from esophageal biopsies is associated with known food triggers.

METHODS

A prior cohort of 21 patients (median age 39 years) with confirmed EoE underwent empirical elimination diets and subsequent reintroduction of foods to determine triggers. Archived baseline biopsies were used to quantify levels of peanut-, milk-, soy-, egg-, wheat-specific and total IgA by enzyme-linked immunosorbent assay.

RESULTS

Overall, 13 patients (62%) responded to the dietary elimination as determined by histology (<15 eos/hpf), with milk and egg being the most common triggers. Biopsies had varying amounts of total IgA, while food-specific IgA was only detectable in 48 of 105 (46%) samples. Food-specific IgA was normalized to total IgA for each sample and stratified by whether a food was a known trigger. For all foods tested, there were no significant differences in IgA between positive and negative triggers.

CONCLUSIONS

Food-specific IgA in esophageal biopsies was not associated with previously identified food triggers in this cohort. Future studies comparing food-specific IgA in esophageal brushings, mucous scrapings, and biopsies from patients with known triggers will be critical to determining whether food-specific IgA may serve as a biomarker for identification of EoE triggers.

Recent Advances in the Treatment of Eosinophilic Esophagitis

Eosinophilic esophagitis is an increasingly common inflammatory allergic disease of the esophagus characterized by esophageal eosinophilia and symptoms of esophageal dysfunction. The therapeutic landscape has rapidly evolved for this emerging type 2 inflammatory disorder. We review traditional therapies including updates and expert opinions in addition to promising therapies on the horizon and the history of therapies that failed to meet end points and highlight knowledge gaps for future investigations.

Non-Invasive and Minimally Invasive Biomarkers for the Management of Eosinophilic Esophagitis beyond Peak Eosinophil Counts: Filling the Gap in Clinical Practice

Eosinophilic esophagitis (EoE) is a chronic esophageal disease that needs lifelong management and follow-up. The diagnosis requires an upper endoscopy with at least one esophageal biopsy demonstrating >15 eosinophils/high-power field, and often occurs with a diagnostic delay of up to ten years, partly due to the absence of valid non-invasive screening tools. In addition, serial upper endoscopies with esophageal biopsies are mandatory to assess the efficacy of any ongoing treatment in patients with EoE. These procedures are invasive, costly, and, when performed without sedation, are often poorly tolerated by patients. Therefore, there is the clinical need to identify reliable non-invasive or minimally invasive biomarkers that could be used to assess disease activity in clinical practice as a surrogate of peak eosinophil counts on esophageal biopsies. This review summarizes evidence on investigational non-invasive or minimally invasive biomarkers for the diagnosis and follow-up of EoE to report on the state of the art in the field and support future research. We discussed eosinophil-derived mediators including eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN, also known as eosinophil protein X), eosinophil peroxidase (EPO), and major basic protein (MBP) as well as other promising non-eosinophil-derived biomarkers. Although several studies have shown the utility of most biomarkers collected from the serum, esophageal luminal secretions, and feces of EoE patients, numerous limitations currently hamper the integration of such biomarkers in clinical practice. Future studies should aim at validating the utility of non-invasive and minimally invasive biomarkers using rigorous protocols and updated consensus criteria for EoE.

The evolving landscape of immunotherapy for the treatment of allergic conditions

Allergic conditions, such as asthma, chronic urticaria, atopic dermatitis (AD), and eosinophilic esophagitis, have long been treated with oral and topical steroids which resulted in negative off-target effects. However, newer biologic medications are increasingly being developed and approved for treatment of these conditions. These medications have a variety of mechanisms of action to target pathophysiology specific to these diseases. As biologics become more targeted, fewer off-target effects are seen improving tolerability for patients as well as expanded options for treatment of these conditions. This review discusses monoclonal antibody therapies (omalizumab, mepolizumab, reslizumab, benralizumab, dupilumab, tezepelumab, and tralokinumab) including their safety and use in asthma, chronic urticaria, AD, and eosinophilic esophagitis.

Medical treatment of eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic antigen-mediated eosinophilic inflammatory disease isolated to the esophagus. As a clinicopathologic disorder, a diagnosis of EoE requires a constellation of clinical symptoms of esophageal dysfunction and histologic findings (at least 15 eosinophils/high-powered microscope field (eos/hpf)). Current guidelines no longer require the failure of response to proton pump inhibitor medications to establish a diagnosis of EoE, but continue to suggest the exclusion of other etiologies of esophageal eosinophilia. The treatment goals for EoE are improvement in clinical symptoms, resolution of esophageal eosinophilia and other histologic abnormalities, endoscopic improvement, improved quality of life, improved esophageal function, minimized adverse effects of treatment, and prevention of disease progression and subsequent complications. Currently, there is no cure for EoE, making long-term treatment necessary. Standard treatment modalities include dietary modifications, esophageal dilation, and pharmacologic therapy. Effective pharmacologic therapies include corticosteroids, rapidly emerging biological therapies, and proton pump inhibitor medications.

OBJECTIVES

To evaluate the efficacy and safety of medical interventions for people with eosinophilic esophagitis.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, and WHO ICTRP to 3 March 2023.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing any medical intervention or food elimination diet for the treatment of eosinophilic esophagitis, either alone or in combination, to any other intervention (including placebo).

DATA COLLECTION AND ANALYSIS

Pairs of review authors independently selected studies and conducted data extraction and risk of bias assessment. We expressed outcomes as a risk ratio (RR) and as the mean or standardized mean difference (MD/SMD) with 95% confidence interval (CI). We assessed the certainty of the evidence using GRADE. Our primary outcomes were: clinical, histological, and endoscopic improvement, and withdrawals due to adverse events. Secondary outcomes were: serious and total adverse events, and quality of life.

MAIN RESULTS

We included 41 RCTs with 3253 participants. Eleven studies included pediatric patients while the rest recruited both children and adults. Four studies were in patients with inactive disease while the rest were in patients with active disease. We identified 19 intervention comparisons. In this abstract we present the results of the primary outcomes for the two main comparisons: corticosteroids versus placebo and biologics versus placebo, based on the prespecified outcomes defined of the primary studies. Fourteen studies compared corticosteroids to placebo for induction of remission and the risk of bias for these studies was mostly low. Corticosteroids may lead to slightly better clinical improvement (20% higher), measured dichotomously (risk ratio (RR) 1.74, 95% CI 1.08 to 2.80; 6 studies, 583 participants; number needed to treat for an additional beneficial outcome (NNTB) = 4; low certainty), and may lead to slightly better clinical improvement, measured continuously (standard mean difference (SMD) 0.51, 95% CI 0.17 to 0.85; 5 studies, 475 participants; low certainty). Corticosteroids lead to a large histological improvement (63% higher), measured dichotomously (RR 11.94, 95% CI 6.56 to 21.75; 12 studies, 978 participants; NNTB = 3; high certainty), and may lead to histological improvement, measured continuously (SMD 1.42, 95% CI 1.02 to 1.82; 5 studies, 449 participants; low certainty). Corticosteroids may lead to little to no endoscopic improvement, measured dichotomously (RR 2.60, 95% CI 0.82 to 8.19; 5 studies, 596 participants; low certainty), and may lead to endoscopic improvement, measured continuously (SMD 1.33, 95% CI 0.59 to 2.08; 5 studies, 596 participants; low certainty). Corticosteroids may lead to slightly fewer withdrawals due to adverse events (RR 0.64, 95% CI 0.43 to 0.96; 14 studies, 1032 participants; low certainty). Nine studies compared biologics to placebo for induction of remission. Biologics may result in little to no difference in clinical improvement, measured dichotomously (RR 1.14, 95% CI 0.85 to 1.52; 5 studies, 410 participants; low certainty), and may result in better clinical improvement, measured continuously (SMD 0.50, 95% CI 0.22 to 0.78; 7 studies, 387 participants; moderate certainty). Biologics result in better histological improvement (55% higher), measured dichotomously (RR 6.73, 95% CI 2.58 to 17.52; 8 studies, 925 participants; NNTB = 2; moderate certainty). We could not draw conclusions for this outcome when measured continuously (SMD 1.01, 95% CI 0.36 to 1.66; 6 studies, 370 participants; very low certainty). Biologics may result in little to no difference in endoscopic improvement, measured dichotomously (effect not estimable, low certainty). We cannot draw conclusions for this outcome when measured continuously (SMD 2.79, 95% CI 0.36 to 5.22; 1 study, 11 participants; very low certainty). There may be no difference in withdrawals due to adverse events (RR 1.55, 95% CI 0.88 to 2.74; 8 studies, 792 participants; low certainty).

AUTHORS' CONCLUSIONS

Corticosteroids (as compared to placebo) may lead to clinical symptom improvement when reported both as dichotomous and continuous outcomes, from the primary study definitions. Corticosteroids lead to a large increase in histological improvement (dichotomous outcome) and may increase histological improvement (continuous outcome) when compared to placebo. Corticosteroids may or may not increase endoscopic improvement (depending on whether the outcome is measured dichotomously or continuously). Withdrawals due to adverse events (dichotomous outcome) may occur less frequently when corticosteroids are compared to placebo. Biologics (as compared to placebo) may not lead to clinical symptom improvement when reported as a dichotomous outcome and may lead to an increase in clinical symptom improvement (as a continuous outcome), from the primary study definitions. Biologics lead to a large increase in histological improvement when reported as a dichotomous outcome, but this is uncertain when reported as a continuous outcome, as compared to placebo. Biologics may not increase endoscopic improvement (dichotomous outcome), but this is uncertain when measured as a continuous outcome. Withdrawals due to adverse events as a dichotomous outcome may occur as frequently when biologics are compared to placebo.

Non-esophageal eosinophilic gastrointestinal diseases: a narrative review

Eosinophilic gastrointestinal disorders are a group of rare diseases characterized by the infiltration of eosinophils in the gastrointestinal wall in a greater amount than in homeostatic conditions. 'Non-esophageal eosinophilic gastrointestinal disorders' is the umbrella term for all eosinophilic gastrointestinal disorders outside of the well known eosinophilic esophagitis. This includes eosinophilic gastritis, eosinophilic enteritis and eosinophilic colitis. The clinical presentation is atypical and not very different for the three disorders. The depth of infiltration has a bigger influence on the presenting symptoms than the disease location. Although the frequency of diagnosis and research in this subject is increasing over time, non-esophageal eosinophilic disorders are rare and high quality evidence is limited to date. In this narrative review, we provide an overview of the latest insights in the pathophysiology, diagnostic approach and available treatment options. Transcriptome studies have found the pathogenesis to be T helper type 2 driven. Various laboratory findings can be used to trigger raised suspicion and investigation with endoscopy. As the endoscopic appearance of the mucosa is normal in most cases, multiple biopsies in each segment are needed to quantify the amount of eosinophils in the tissue. Eosinophilic cut-offs for diagnosis are a controversial topic and a consensus is still lacking. A recently developed tissue based diagnostic platform which measures differentially expressed genes might be available in the future to classify patients with intermediate eosinophilic tissue levels under the cut-off. For the treatment, corticosteroids are still the cornerstone of treatment but promising research suggests a role of biologicals, such as Lirentelimab (anti-siglec 8) in particular.

Food allergy: cause or consequence of pediatric eosinophilic esophagitis? Potential implications of ultraprocessed foods in prevention and management

Eosinophilic esophagitis (EoE) is a chronic, immune-mediated disease characterized by eosinophilic infiltration, leading to esophageal dysfunction, inflammation, and fibrotic remodeling. In the last few decades, there has been an increased prevalence of EoE at an alarming rate in the pediatric age. The pathogenesis of EoE is still largely undefined, and this limits the definition of effective strategies for the prevention and management of this condition. EoE is considered a multifactorial disease arising from a negative interaction between environmental factors and genetic background, causing an impaired esophageal epithelial barrier with subsequent abnormal allergen exposure activating type 2 (Th2) inflammation. Food antigens have been suggested as key players in Th2 inflammation in pediatric patients with EoE, but emerging evidence suggests a potential role of other dietary factors, including ultraprocessed foods, as possible triggers for the occurrence of EoE. In this paper, we discuss the potential role of these dietary factors in the development of the disease, and we propose a new approach for the management of pediatric patients with EoE.

Food-Specific IgG4 Is Elevated Throughout the Upper Gastrointestinal Tract in Eosinophilic Esophagitis

BACKGROUND

Food-specific immunoglobulin G4 (FS-IgG4) is associated with eosinophilic esophagitis (EoE); however, it is not clear whether production is limited to the esophagus.

AIMS

To assess FS-IgG4 levels in the upper gastrointestinal tract and plasma and compare these with endoscopic disease severity, tissue eosinophil counts, and patient-reported symptoms.

METHODS

We examined prospectively banked plasma, throat swabs, and upper gastrointestinal biopsies (esophagus, gastric antrum, and duodenum) from control (n = 15), active EoE (n = 24), and inactive EoE (n = 8) subjects undergoing upper endoscopy. Patient-reported symptoms were assessed using the EoE symptom activity index (EEsAI). Endoscopic findings were evaluated using the EoE endoscopic reference score (EREFS). Peak eosinophils per high-power field (eos/hpf) were assessed from esophageal biopsies. Biopsy homogenates and throat swabs were normalized for protein content and assessed for FS-IgG4 to milk, wheat, and egg.

RESULTS

Median FS-IgG4 for milk and wheat was significantly increased in the plasma, throat swabs, esophagus, stomach, and duodenum of active EoE subjects compared to controls. No significant differences for milk- or wheat-IgG4 were observed between active and inactive EoE subjects. Among the gastrointestinal sites sampled, FS-IgG4 levels were highest in the esophagus. Esophageal FS-IgG4 for all foods correlated significantly across all sites sampled (r ≥ 0.59, p < 0.05). Among subjects with EoE, esophageal FS-IgG4 correlated significantly with peak eos/hpf (milk and wheat) and total EREFS (milk). EEsAI scores and esophageal FS-IgG4 levels did not correlate.

CONCLUSIONS

Milk and wheat FS-IgG4 levels are elevated in plasma and throughout the upper gastrointestinal tract in EoE subjects and correlate with endoscopic findings and esophageal eosinophilia.

One-food versus six-food elimination diet therapy for the treatment of eosinophilic oesophagitis: a multicentre, randomised, open-label trial

BACKGROUND

Empirical elimination diets are effective for achieving histological remission in eosinophilic oesophagitis, but randomised trials comparing diet therapies are lacking. We aimed to compare a six-food elimination diet (6FED) with a one-food elimination diet (1FED) for the treatment of adults with eosinophilic oesophagitis.

METHODS

We conducted a multicentre, randomised, open-label trial across ten sites of the Consortium of Eosinophilic Gastrointestinal Disease Researchers in the USA. Adults aged 18-60 years with active, symptomatic eosinophilic oesophagitis were centrally randomly allocated (1:1; block size of four) to 1FED (animal milk) or 6FED (animal milk, wheat, egg, soy, fish and shellfish, and peanut and tree nuts) for 6 weeks. Randomisation was stratified by age, enrolling site, and gender. The primary endpoint was the proportion of patients with histological remission (peak oesophageal count <15 eosinophils per high-power field [eos/hpf]). Key secondary endpoints were the proportions with complete histological remission (peak count ≤1 eos/hpf) and partial remission (peak counts ≤10 and ≤6 eos/hpf) and changes from baseline in peak eosinophil count and scores on the Eosinophilic Esophagitis Histology Scoring System (EoEHSS), Eosinophilic Esophagitis Endoscopic Reference Score (EREFS), Eosinophilic Esophagitis Activity Index (EEsAI), and quality of life (Adult Eosinophilic Esophagitis Quality-of-Life and Patient Reported Outcome Measurement Information System Global Health questionnaires). Individuals without histological response to 1FED could proceed to 6FED, and those without histological response to 6FED could proceed to swallowed topical fluticasone propionate 880 μg twice per day (with unrestricted diet), for 6 weeks. Histological remission after switching therapy was assessed as a secondary endpoint. Efficacy and safety analyses were done in the intention-to-treat (ITT) population. This trial is registered on ClinicalTrials.gov, NCT02778867, and is completed.

FINDINGS

Between May 23, 2016, and March 6, 2019, 129 patients (70 [54%] men and 59 [46%] women; mean age 37·0 years [SD 10·3]) were enrolled, randomly assigned to 1FED (n=67) or 6FED (n=62), and included in the ITT population. At 6 weeks, 25 (40%) of 62 patients in the 6FED group had histological remission compared with 23 (34%) of 67 in the 1FED group (difference 6% [95% CI -11 to 23]; p=0·58). We found no significant difference between the groups at stricter thresholds for partial remission (≤10 eos/hpf, difference 7% [-9 to 24], p=0·46; ≤6 eos/hpf, 14% [-0 to 29], p=0·069); the proportion with complete remission was significantly higher in the 6FED group than in the 1FED group (difference 13% [2 to 25]; p=0·031). Peak eosinophil counts decreased in both groups (geometric mean ratio 0·72 [0·43 to 1·20]; p=0·21). For 6FED versus 1FED, mean changes from baseline in EoEHSS (-0·23 vs -0·15; difference -0·08 [-0·21 to 0·05]; p=0·23), EREFS (-1·0 vs -0·6; difference -0·4 [-1·1 to 0·3]; p=0·28), and EEsAI (-8·2 vs -3·0; difference -5·2 [-11·2 to 0·8]; p=0·091) were not significantly different. Changes in quality-of-life scores were small and similar between the groups. No adverse event was observed in more than 5% of patients in either diet group. For patients without histological response to 1FED who proceeded to 6FED, nine (43%) of 21 reached histological remission; for patients without histological response to 6FED who proceeded to fluticasone propionate, nine (82%) of 11 reached histological remission.

INTERPRETATION

Histological remission rates and improvements in histological and endoscopic features were similar after 1FED and 6FED in adults with eosinophilic oesophagitis. 6FED had efficacy in just less than half of 1FED non-responders and steroids had efficacy in most 6FED non-responders. Our findings indicate that eliminating animal milk alone is an acceptable initial dietary therapy for eosinophilic oesophagitis.

FUNDING

US National Institutes of Health.

Eosinophilic gastroenteritis: Pathogenesis, diagnosis, and treatment

ABSTRACT

Eosinophilic gastroenteritis (EGE) is a gastrointestinal disorder of unclear etiology that is characterized by eosinophilic infiltration of the stomach and small intestine, and consists of mucosal, muscular, and serosal subtypes. Eosinophilic infiltration of the gastrointestinal tract is a fundamental histopathological characteristic of EGE and is driven by several T-helper type 2 (Th2)-dependent cytokines and induced by food allergy. Due to the lack of a diagnostic gold standard, EGE has a high rate of delayed diagnosis or misdiagnosis. However, several new diagnostic strategies have been developed, such as novel genetic biomarkers and imaging tests. Although dietary therapy and corticosteroids remain the common choices for EGE treatment, recent decades have seen the emergence of novel treatment alternatives, such as biologics that target particular molecules involved in the pathogenic process. Preliminary investigations and clinical trials have demonstrated the efficacy of biologics and provided additional insights for the era of refractory or corticosteroid-dependent EGE biologics.

Eosinophilic Esophagitis—What Do We Know So Far?

Eosinophilic esophagitis is a Th-2 antigen-mediated disease in which there is an influx of eosinophils to all layers of the esophagus, triggering an inflammatory response. Chronic inflammatory process causes esophageal remodeling, leading to difficulties in swallowing. Food impaction, heartburn, and chest pain are other characteristic (but not pathognomonic) symptoms in adults. Although the disease has only been described since in the early 1970s, its incidence and prevalence are rapidly growing, especially in Western countries. According to the diagnostic guidelines, there should be at least 15 eosinophils visible per high-power field in biopsies obtained from different sites in the esophagus upon endoscopy with relevant esophageal symptoms. Other diseases that can cause esophageal eosinophilia should be ruled out. Eosinophilic esophagitis treatment may be challenging; however, new methods of management have recently emerged. The currently used proton pump inhibitors, topical corticosteroids, and elimination diet are combined with biological treatment. New methods for disease diagnostics and clinical course assessment are also available. This review presents current knowledge about the disease, supported by the latest research data.

Outcomes reported in randomized controlled trials for mixed and non-IgE-mediated food allergy: Systematic review

BACKGROUND

Mixed and non-IgE-mediated food allergy is a subset of immune-mediated adverse food reactions that can impose a major burden on the quality of life of affected patients and their families. Clinical trials to study these diseases are reliant upon consistent and valid outcome measures that are relevant to both patients and clinicians, but the degree to which such stringent outcome reporting takes place is poorly studied.

OBJECTIVE

As part of the Core Outcome Measures for Food Allergy (COMFA) project, we identified outcomes reported in randomized clinical trials (RCT) of treatments for mixed or non-IgE-mediated food allergy.

DESIGN

In this systematic review, we searched the Ovid, MEDLINE and Embase databases for RCTs in children or adults investigating treatments for food protein-induced enterocolitis syndrome, food protein-induced allergic proctocolitis, food protein-induced enteropathy and eosinophilic gastrointestinal disorders including eosinophilic esophagitis [EoE], eosinophilic gastritis and eosinophilic colitis published until 14 October 2022.

RESULTS

Twenty-six eligible studies were identified, with 23 focused on EoE (88%). Most interventions were corticosteroids or monoclonal antibodies. All EoE studies assessed patient-reported dysphagia, usually using a non-validated questionnaire. Twenty-two of 23 EoE studies used peak tissue eosinophil count as the primary outcome, usually using a non-validated assessment method, and other immunological markers were only exploratory. Thirteen (57%) EoE studies reported endoscopic outcomes of which six used a validated scoring tool recently recommended as a core outcome for EoE trials. Funding source was not obviously associated with likelihood of an RCT reporting mechanistic versus patient-reported outcomes. Only 3 (12%) RCTs concerned forms of food allergy other than EoE, and they reported on fecal immunological markers and patient-reported outcomes.

CONCLUSIONS

Outcomes measured in clinical trials of EoE and non-IgE-mediated food allergy are heterogeneous and largely non-validated. Core outcomes for EoE have been developed and need to be used in future trials. For other forms of mixed or non-IgE-mediated food allergies, core outcome development is needed to support the development of effective treatments.

SYSTEMATIC REVIEW REGISTRATION

OSF public registry DOI:10.17605/OSF.IO/AZX8S.

The role of biologics in pediatric food allergy and eosinophilic gastrointestinal disorders

Continuing insight into the molecular mechanisms of atopic disorders has enabled the development of biologics to precisely target these diseases. Food allergy (FA) and eosinophilic gastrointestinal disorders (EGIDs) are driven by similar inflammatory molecular mechanisms and exist along the same atopic disease spectrum. Therefore, many of the same biologics are being investigated to target key drivers of mechanisms shared across the disease states. The enormous potential of biologics for the treatment of FA and EGIDs is highlighted by the significant increases in the number of ongoing clinical trials (more than 30) evaluating their use in these disease states, as well as by the recent US Food and Drug Administration approval of dupilumab for the treatment of eosinophilic esophagitis. Here we discuss past and current research into the use of biologics in FA and EGIDs and their potential role in improving treatment options in the future, with the need to have biologics widely clinically available.

Food antigen consumption and disease activity affect food-specific IgG4 levels in patients with eosinophilic esophagitis (EoE)

INTRODUCTION

High levels of serum food-specific IgG4 (sIgG4) have been reported in patients with EoE. The objective of this study was to examine whether serum sIgG4 levels to foods and aeroallergens are higher in EoE patients than allergic controls and to investigate the association between sIgG4 and EoE clinical characteristics.

METHODS

This was a case-control study nested in a prospective EoE Cohort. EoE cases were defined per consensus guidelines, and controls were individuals with symptoms who were confirmed to be EoE-negative on upper endoscopy. Demographic and clinical information was prospectively collected. Serum IgE and sIgG4 were measured to foods and aeroallergens by ImmunoCAP. Mean levels of sIgG4 were compared between cases and controls, and logistic regression models were used to examine predictors of elevated milk sIgG4 levels.

RESULTS

The analysis included 123 individuals (EoE n = 93, control n = 30) with a similar distribution of allergic disease between EoE patients and controls (86% vs. 93%; p = .30). EoE patients had significantly higher sIgG4 levels to all allergens evaluated, with the exception of birch (p = .24). Milk sIgG4 levels were independently associated with milk consumption (OR 4.95; p = .01) and the presence of sIgE to milk (OR 4.23; p = .008).

CONCLUSION

Serum sIgG4 levels to food and aeroallergen proteins were higher in patients with EoE than non-EoE controls, and higher levels of milk sIgG4 were independently associated with milk consumption and the presence of sIgE to milk proteins. Whether sIgG4 plays a pathogenic role in EoE or could be used as an EoE biomarker remains unknown and warrants further study.

Eosinophilic Esophagitis

This chapter presents an overview of eosinophilic esophagitis (EoE) for the Primary Care Practitioner (PCP). The focus is on helping PCPs keep it in their differential diagnosis by discussing the spectrum of clinical presentations, how to screen for EoE in at-risk populations and subsequently manage the patient with this condition. The authors review epidemiology, risk factors and associated conditions, pathology, clinical presentation, diagnosis, and management options.

Food elimination diets in eosinophilic esophagitis: Practical tips in current management and future directions

Eosinophilic esophagitis (EoE) is a chronic, antigen-mediated disease of the esophagus characterized by symptoms of esophageal dysfunction and an eosinophil-predominant inflammation. Seminal reports identified the role of food allergens in the pathogenesis of the disease by demonstrating that food avoidance could lead to the resolution of esophageal eosinophilia in EoE patients. Although pharmacological treatments for EoE are increasingly being investigated, the exclusion of trigger foods from the diet still represents a valuable option for patients to achieve and maintain disease remission without drugs. Food elimination diets are variegated, and one size does not fit all. Accordingly, before starting any elimination diet, patients' characteristics should be thoroughly evaluated, and a rigorous management plan should be defined. This review provides practical tips and considerations to succeed in the management of EoE patients undergoing food elimination diets, as well as recent advances and future perspectives on food avoidance strategies.

Mechanisms and clinical management of eosinophilic oesophagitis: an overview

Since the first description of eosinophilic oesophagitis (EoE) less than three decades ago, we have observed a striking increase in the number of patients diagnosed with EoE and the understanding of its clinical and immunopathogenic background. Nonetheless, a plethora of open questions await elucidation. In this Review, we discuss the current state of knowledge regarding the underlying mechanisms, particularly environmental factors and their interaction with genetic susceptibility. Subsequently, we discuss how to translate these factors into the diagnostic and therapeutic management of this chronic, immune-mediated disorder. Finally, we dissect the still long list of unmet needs, such as reasons for and handling refractory EoE and atypical clinical presentations. These open questions can guide us through future research steps and potentially foster reconsideration of the diagnostic guidelines of EoE.

Increase in distal esophageal wall thickness with time in adult patients with eosinophilic esophagitis

Background and Aim

Eosinophilic esophagitis (EoE) is a chronic disease which may progress to a fibro-stenotic phenotype due to esophageal sub-epithelial fibrosis. Esophageal wall thickening in patients with EoE has been demonstrated in a few studies using endoscopic ultrasound (EUS). The aim of this study was to longitudinally assess the endoscopic appearance, wall thickness, histology, and dysphagia score of EoE patients.

Methods

Patients with EoE were recruited and studied between February 2012 and April 2021. Patients were evaluated on two separate occasions at least 12 months apart with endoscopy, EUS, and esophageal mucosal biopsies. The dysphagia score and epidemiology data were also assessed.

Results

A total of 16 EoE patients were included with a mean follow-up duration of 2.2 ± 1.2 years. In 14/16 (88%) patients, the total wall thickness of the distal esophagus significantly increased (P = 0.0012) as a result of thickening of the muscularis propria (P = 0.0218). However, only 1/14 (7%) patient had an increase in the dysphagia score, while 8/14 (57%) and 5/14 (36%) had a stable and reduced dysphagia score, respectively. No differences were found in the total thickness of other esophageal regions, dysphagia score, endoscopic appearance, and eosinophil count over time.

Conclusion

Distal esophageal wall thickness increases with time in EoE patients, independent of the dysphagia score and eosinophil count.

IgG4+ cells are increased in the gastrointestinal tissue of pediatric patients with active eosinophilic gastritis and duodenitis and decrease in remission

BACKGROUND

Recent studies have shown that IgG4 is increased in the esophageal tissue of eosinophilic esophagitis patients, including the presence of IgG4+ plasma cells.

AIMS

Our aim was to determine whether IgG4 is elevated in the gastric or duodenal tissue of pediatric patients with eosinophilic gastritis or duodenitis (EoG or EoD).

METHODS

This was a retrospective single center study. Pediatric patients were characterized as having active EoG, EoD, or as controls based on clinical symptoms and histologic features. Immunohistochemistry for IgG4 was performed in gastric and duodenal tissue, and peak IgG4+ cells were compared between groups and after treatment.

RESULTS

The frequency of IgG4+ cells was significantly higher in patients with EoG and EoD compared to controls in the stomach [EoG 6.5 cells/hpf (3.6-10.9), control 0 cells/hpf (0-0.7), p<0.0001] and duodenum [EoD 7.5 cells/hpf (2.8-37), control 0.5 cells/hpf (0.3-1.3), p<0.001)] respectively, and positively correlated with eosinophil counts (stomach: r 0.74, p<0.0001; duodenum: r 0.57, p<0.0001). The amount of tissue IgG4 was significantly decreased in patients in remission but not in persistently active disease.

CONCLUSIONS

These data suggest local tissue production of IgG4 may be a universal feature of eosinophilic gastrointestinal disease that tracks with disease activity.

Biologics in eosinophilic gastrointestinal diseases

Eosinophilic gastrointestinal diseases are a constellation of conditions categorized by the location of eosinophilic infiltration in the gastrointestinal tract. Symptoms vary based on location of eosinophils and age of the patient. There are no approved medications at the current time with individuals using off-label steroids or dietary therapy. Translational research has identified potential pathways to target in the treatment of eosinophilic esophagitis (EoE), gastritis (EoG), and enteritis (EoN), including type 2 pathways, mast cells, and eosinophils. Preliminary studies found cendakimab (anti-interleukin [IL]-13) and dupilumab (anti-IL-4 receptor alpha) to have an effect on eosinophil count and symptoms with dupilumab recently approved. In addition, mepolizumab (anti-IL-5), reslizumab (anti-IL-5), and lirentelimab (anti-Siglec 8) were found to have reduction in eosinophils without reduction of symptoms. For EoG and EoN, both benralizumab (anti-IL-5 receptor) and lirentelimab were found to have histologic and symptom improvement. There are no agents studied for eosinophilic colitis. Results of ongoing phase 3 trials in EoE and EoG/EoN are also anticipated.

Breaking down the complex pathophysiology of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is a chronic and progressive immune-mediated disease of the esophagus associated with antigen-driven type 2 inflammation and symptoms of esophageal dysfunction. Our understanding of EoE pathophysiology has evolved since its initial recognition more than 20 years ago and has translated into diagnostic and novel therapeutic approaches that are affecting patient care. The mechanisms underlying disease development and progression are influenced by diverse factors, such as genetics, age, allergic comorbidities, and allergen exposures. Central to EoE pathophysiology is a dysregulated feed-forward cycle that develops between the esophageal epithelium and the immune system. Allergen-induced, type 2-biased immune activation by the esophageal epithelium propagates a cycle of impaired mucosal barrier integrity and allergic inflammation, eventually leading to tissue remodeling and progressive organ dysfunction. Herein, we review the current understanding of fundamental pathophysiological mechanisms contributing to EoE pathogenesis.

Scientific journey to the first FDA-approved drug for eosinophilic esophagitis

When eosinophilia was first associated with esophagitis, it was thought to reflect gastroesophageal reflux disease, especially given the efficacy of reflux medications to abate esophageal eosinophilia in many individuals. Subsequent studies demonstrated disease remittance with amino acid-based formulas and conversely induction of esophageal eosinophilia in mice following allergen challenge. These results, along with the finding that proton pump inhibitors alleviated esophageal eosinophilia by an anti-inflammatory mechanism, turned attention away from an acid-induced pathogenesis and established eosinophilic esophagitis (EoE) as a separate disease entity driven by allergic inflammation. The disease underpinnings were elucidated by analysis of esophageal transcriptomic profiling, revealing gene signatures orchestrated by type 2 cytokine signaling, mainly IL-13. Preclinical studies showed that IL-13 overproduction was sufficient to induce EoE-like changes in mice and human ex vivo systems and conversely that inhibiting IL-13 signaling attenuated these processes. An early proof-of-principle study with a humanized anti-IL-13 mAb in patients with EoE revealed correction of the EoE transcriptome and attenuation of esophageal eosinophilia, providing a rationale for advancing anti-type 2 cytokine therapy for EoE. Dupilumab, a precision therapeutic mAb that blocks the shared IL-13 and IL-4 receptor, is the first drug to advance through clinical trials and receive US Food and Drug Administration approval for EoE. The ability of dupilumab to improve clinical, histologic, endoscopic, and molecular features of EoE and garner US Food and Drug Administration approval is a victory for science, rare diseases, patients, and advocacy and provides a framework for developing additional EoE treatments and approved treatments for eosinophilic gastrointestinal disease beyond the esophagus.