Esophageal IgE, IgG4, and mucosal eosinophilia in individuals with dysphagia

Circulating Food Allergen-Specific Antibodies, Beyond IgG4, Are Elevated in Eosinophilic Esophagitis

INTRODUCTION

Eosinophilic esophagitis (EoE) is a chronic inflammatory condition with an incompletely understood immuno-pathogenesis involving a T2 response. EoE is triggered by food allergens although, unlike IgE-mediated allergies, it exhibits high IgG4 levels in oesophageal biopsies and in circulation. We investigated whether other antibody isotypes specific for food allergens are elevated in EoE and vary with disease activity.

METHODS

Plasma samples from patients with active EoE (n = 51), inactive EoE (n = 82) and non-EoE controls (n = 14) were analysed for food-specific IgG and IgA subclasses against casein, whey, wheat, egg and individual cow's milk allergens by ELISA. α-lactalbumin (Bos d 4)- and β-lactoglobulin (Bos d 5)-specific B cells were measured by flow cytometry in a subset of patients.

RESULTS

Food allergen-specific antibodies in the plasma varied across EoE subgroups and non-EoE controls. Elevated IgG4 in EoE patients confirmed a strong antibody response to food allergens, including casein, wheat and egg. αS1-casein (Bos d 9)-specific IgG, IgG2, IgG4, IgA1 and IgA2 differed between EoE and non-EoE controls and between active and inactive EoE. β-casein (Bos d 11, A1 variant) measurements showed higher levels of specific IgG2 and IgG4 in both EoE groups, whereas whey-derived allergens showed opposing responses: Bos d 4 responses favoured IgG4, and Bos d 5 responses were elevated across multiple IgG and IgA subclasses in EoE. Allergen-specific B cells could not be isolated from the circulation.

CONCLUSION

Our findings reveal distinct antibody profiles in EoE plasma, with elevated IgG and IgA subclasses beyond IgG4, highlighting a complex immune response to food allergens. Differential antibody responses support their clinical relevance in dietary management strategies, while the absence of allergen-specific B cells in circulation likely restricts antibody production to the inflamed oesophagus. Future research should explore whether these antibody profiles can guide personalised treatment and novel therapeutic targets in EoE.

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.

Gastrointestinal IgG4 Deposition Is a New Histopathological Feature of Eosinophilic Gastroenteritis

BACKGROUND

The pathogenesis of eosinophilic esophagitis involves immunoglobulin G4 (IgG4) deposition. However, the relationship between IgG4 and eosinophilic gastroenteritis (EGE) is unclear.

AIMS

To investigate gastrointestinal deposition of IgG4 in EGE.

METHODS

Biopsies of the esophagus, stomach, and small intestine were evaluated in patients with and without EGE. Immunohistochemical staining for IgG4 was performed, and the proportions of the stained areas were compared. Sera from patients with EGE were assayed for food-specific IgG4, including egg white, wheat, rice, soy, and cow milk.

RESULTS

Seventeen patients were included in this study (EGE group, n = 10; control group, n = 7). Compared with the control group, the proportion of IgG4-stained area in the EGE group was approximately threefold higher (40.2% [32.3-49.5]) vs. 12.1% [4.0-21.9], p = 0.014) in the esophagus, fivefold higher in the stomach (17.3% [11.1-26.2] vs. 3.7% [1.5-5.2], p = 0.014), and sixfold higher in the small intestine (28.0% [15.0-33.2] vs. 4.5% [2.6-9.8], p = 0.019). There was no significant association between the proportion of IgG4-stained area and the number of infiltrating eosinophils. Serum egg white-specific IgG4 levels were correlated with the proportion of IgG4-stained areas in the small intestine (R = 0.7, p = 0.035).

CONCLUSIONS

IgG4 accumulated within the gastrointestinal mucosa in EGE. The positive correlation between serum egg white-specific IgG4 levels and the proportion of IgG4-stained areas in the small intestine suggests a role for IgG4 in the disease pathophysiology.

British Society of Gastroenterology (BSG) and British Society of Paediatric Gastroenterology, Hepatology and Nutrition (BSPGHAN) joint consensus guidelines on the diagnosis and management of eosinophilic oesophagitis in children and adults

BACKGROUND

Eosinophilic oesophagitis (EoE) is an increasingly common cause of dysphagia in both children and adults, as well as one of the most prevalent oesophageal diseases with a significant impact on physical health and quality of life. We have provided a single comprehensive guideline for both paediatric and adult gastroenterologists on current best practice for the evaluation and management of EoE.

METHODS

The Oesophageal Section of the British Society of Gastroenterology was commissioned by the Clinical Standards Service Committee to develop these guidelines. The Guideline Development Group included adult and paediatric gastroenterologists, surgeons, dietitians, allergists, pathologists and patient representatives. The Population, Intervention, Comparator and Outcomes process was used to generate questions for a systematic review of the evidence. Published evidence was reviewed and updated to June 2021. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system was used to assess the evidence and make recommendations. Two rounds of voting were held to assess the level of agreement and the strength of recommendations, with 80% consensus required for acceptance.

RESULTS

Fifty-seven statements on EoE presentation, diagnosis, investigation, management and complications were produced with further statements created on areas for future research.

CONCLUSIONS

These comprehensive adult and paediatric guidelines of the British Society of Gastroenterology and British Society of Paediatric Gastroenterology, Hepatology and Nutrition are based on evidence and expert consensus from a multidisciplinary group of healthcare professionals, including patient advocates and patient support groups, to help clinicians with the management patients with EoE and its complications.

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.

Immunohistochemical markers for eosinophilic esophagitis

BACKGROUND AND AIMS

Eosinophilic esophagitis (EoE) is a chronic, local immune-mediated esophageal disease with eosinophil-dominated inflammation. The incidence of the disease is rapidly increasing in both children and adults. The pathogenesis of the disease is still not well understood. We present a review of the literature devoted to the EoE immunopathology, in particular the markers of inflammation and epithelial integrity, and their usefulness in disease monitoring and therapy.

METHODS

We performed a systematic search of the MEDLINE/PubMed databases for studies to examine the use of immunohistochemistry as a diagnostic tool for EoE.

RESULTS

The gold standard of EoE diagnosis requires multiple endoscopies with biopsies for histological assessment. The minimum number of eosinophils evaluated in hematoxylin-eosin staining to diagnose EoE is 15 per high-power field in at least one esophageal mucosa biopsy. However, in some cases, the count of eosinophils is not specific and insufficient as the only indicator. Recent works confirm the usefulness of assessment of some biomarkers in establishing the diagnosis and monitoring the treatment effects.

CONCLUSIONS

Immunohistochemistry seems to be a promising option not only in clinical recognition, but also in the selection and monitoring of treatment effects. However, these methods have not yet recommended for routine clinical use.

Food-specific antibodies in oesophageal secretions: association with trigger foods in eosinophilic oesophagitis

BACKGROUND

Food antigens are clearly implicated in the induction and persistence of eosinophilic oesophagitis. Dietary elimination to identify triggers is tedious and expensive. Alternatives that can mitigate cost and improve patient quality of life during this process are needed.

AIMS

To test the hypothesis that antibodies against foods that trigger eosinophilic oesophagitis are secreted into the oesophageal lumen where they can be collected by oesophageal brushings.

METHODS

We evaluated food-specific immune responses within brushings in 68 patients undergoing endoscopy (12 controls, 13 resolved eosinophilic oesophagitis and 43 active eosinophilic oesophagitis). Seventeen participants identified their trigger foods via food elimination diets. Immunoglobulin A and immunoglobulin G4 antibodies against the four most common eosinophilic oesophagitis food triggers were measured using the ImmunoCAP assay in the oesophageal brushings. Food-specific antibody values were compared between active eosinophilic oesophagitis, resolved eosinophilic oesophagitis and controls.

RESULTS

Patients with active eosinophilic oesophagitis (>15 eosinophils/hpf) demonstrated increased immunoglobulin A and immunoglobulin G4 levels to common eosinophilic oesophagitis triggers compared to controls (327 ± 380 vs 150 ± 130 for immunoglobulin A, and 1534 ± 3346 vs 178 ± 123 for immunoglobulin G4, P < 0.003). Specific trigger foods were associated with elevated immunoglobulin A and immunoglobulin G4 responses compared to foods that did not trigger oesophageal eosinophilia (733 ± 469 vs 142 ± 64, P < 0.001 immunoglobulin A and 2620 ± 3228 vs 526 ± 1050, P < 0.001 immunoglobulin G4).

CONCLUSIONS

Food-specific antibodies are easily collected along the oesophageal lumen of eosinophilic oesophagitis patients. Further studies are needed to validate our preliminary findings to determine whether these antibodies can be used to guide elimination diet therapy.