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

Type 2 airway inflammation in COPD

Globally, nearly 400 million persons have COPD, and COPD is one of the leading causes of hospitalisation and mortality across the world. While it has been long-recognised that COPD is an inflammatory lung disease, dissimilar to asthma, type 2 inflammation was thought to play a minor role. However, recent studies suggest that in approximately one third of patients with COPD, type 2 inflammation may be an important driver of disease and a potential therapeutic target. Importantly, the immune cells and molecules involved in COPD-related type 2 immunity may be significantly different from those observed in severe asthma. Here, we identify the important molecules and effector immune cells involved in type 2 airway inflammation in COPD, discuss the recent therapeutic trial results of biologicals that have targeted these pathways and explore the future of therapeutic development of type 2 immune modulators in COPD.

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.

Proton-Pump Inhibitors in Eosinophilic Esophagitis: A Review Focused on the Role of Pharmacogenetics

Proton-pump inhibitors (PPIs) are the most administered first-line treatment for eosinophilic esophagitis (EoE). However, only around half of EoE patients respond histologically to a double dosage of PPI. In addition, 70% of responders maintain EoE in remission after tapering the PPI dose. In order to avoid endoscopy with biopsies-the only accurate method of assessing PPI response-efforts have been made to identify PPI responder patients. The clinical or endoscopic features and biomarkers evaluated so far, however, have not proven to be sufficient in predicting PPI response. Although new approaches based on omics technologies have uncovered promising biomarkers, the specialized and complex procedures required are difficult to implement in clinical settings. Alternatively, PPI pharmacogenetics based on identifying variations in CYP2C19 and STAT6 genes have shown promising results in EoE, and could easily be performed in most laboratories. Other genetic variations have also been associated with PPI response and may explain those cases not related to CYP2C19 or STAT6. Here, we provide an overview of PPI treatment in EoE and evidence of how genetic variations in CYP2C19 and other genes could affect PPI effectiveness, and also discuss studies evaluating the role of pharmacogenetics in predicting PPI response in patients with EoE.

Eosinophilic esophagitis and duodenal food challenge - evaluation through endoscopic confocal laser endomicroscopy

BACKGROUND

Endoscopic confocal laser endomicroscopy (eCLE) is an established technique that allows clinical evaluation of mucosal integrity by fluorescein leaking through the mucosa upon duodenal food challenge (DFC). Analysis of eCLE with DFC in eosinophilic esophagitis (EoE) would be interesting to evaluate epithelial barrier dysfunction also in other regions of the gastrointestinal tract and to characterize potential individual food allergens that trigger the esophageal inflammation.

METHODS

In an observational and proof of concept study we evaluated 9 patients with histologically proven EoE by eCLE and DFC. Severity of symptoms were graduated according to the validated symptom-based EoE activity index. The endoscopic appearance of the esophagus was described according to the Endoscopic Reference Score System (ERERS). Spontaneous and food induced transfer of fluorescein into duodenal lumen were detected 10 minutes following intravenously application of fluorescein and 10 minutes after DFC. Food allergens were yeast, egg, soy, milk, and wheat, respectively. Local application of sodium chloride solution 10 % to the duodenal mucosa before DFC served as a control. Patients responding to DFC received a dietary exclusion therapy according to the results of DFC.

RESULTS

We investigated 9 patients with EoE (8 men, 49.7±13.8, 36-76 years). Symptom-based EoE activity index was 79±27.4, 33-100. In all patients EoE was confirmed by histology with number of esophageal mucosal eosinophilic granulocytes > 15/HPF, (91.4±77.4, 42-263). Mean ERERS score was 4.5±1.3, 3-7. None of the patients was aware of any food intolerance. eCLE revealed one patient with spontaneous transfer of i. v. fluorescein into duodenal lumen before DFC ("leaky gut"). 40 DFC were performed in the remaining 8 patients of whom 5 patients (61 %) responded to DFC. Rank order of fluorescein leakage upon DFC was wheat and milk in 37.5 % each, soy in 25 %, and egg in 12.5 %. The patients were treated by PPI (n=9), esophageal bouginage (n=5) and/or local corticoid therapy (n=3). The 5 patients responding to DFC received an additional food exclusion dietary advice focussed on the results of DFC. All patients reported a reduction of their symptoms. EoE activity indexes of patients with positive DFC were 73.7+28.6, 33-100 before and 22.7+37.9, 0-79 four weeks after food exclusion.

CONCLUSION

The findings of our proof of concept study suggest that eCLE with DFC may be an interesting tool to further evaluate patients with EoE. This technique has the potential to identify patients who may benefit from an additional individual dietary therapy.

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.

Vernal keratoconjunctivitis and eosinophilic esophagitis: A rare combination?

Vernal keratoconjunctivitis (VKC) is a bilateral ocular inflammatory disease with a conjunctival and corneal involvement and typical onset during childhood. Eosinophilic esophagitis (EoE) is a chronic disease characterized by eosinophilic inflammation of the mucosa (≥15 eosinophils/HPF) and symptoms of esophageal dysfunction. EoE and VKC are both immune-mediated diseases sharing a similar pathogenetic mechanism and a high association with other allergic diseases. Nevertheless, no data are currently available about their clinical association. We present 4 cases of concomitant diagnosis of vernal keratoconjunctivitis and eosinophil esophagitis suggesting that these conditions may coexist in the same patient more frequently than expected. Health care providers should be aware of the possibility of co-occurrence in their daily practice.

[Pathomorphological criteria and features of immune response in eosinophilic esophagitis and reflux esophagitis]

BACKGROUND

Eosinophilic esophagitis (EoE) is an immune-mediated disease, manifested by dysphagia and characterized by intraepithelial infiltration: more than 15 eosinophils per field of view at x400 magnification, and requiring differential diagnosis with reflux esophagitis (RE).

OBJECTIVE

To access the implication of EoE histologic scoring system (EoEHSS) for differential diagnosis of EoE and RE and to characterize features of immune response in these diseases.

MATERIAL AND METHODS

38 patients with EoE and 38 patients with RE were enrolled in the study. All the patients had esophagogastroduodenoscopy with biopsy. Biopsy specimens were stained with H&E and combined PAS/Alcian blue staining. Immunohistochemical evaluation was conducted with antibodies to CD3, CD4, CD8, CD20, CD56 and CD68.

RESULTS

Grade score of EoEHSS in EoE was 2.4 times more than in RE (p<0.05). Stage score in EoE was 2.75 more than in RE (p<0.05). Intraepithelial count of CD3+ T-lymphocytes comprised 87 (76-95.5) in high-power view in EoE and 45 (38.5-48.5) in high-power view in RE. Intraepithelial count of CD4+ T-lymphocytes was 35 (28-41.5) in high-power view in EoE and 19 (16.5- 22.5) in high-power view in RE. Intraepithelial count of CD8+ T-lymphocytes comprised 59 (50.5-67.5) in high-power field in EoE and 27 (24-28.5) in high-power field in RE.

CONCLUSION

The use of the EoEHSS histological rating scale for eosinophilic esophagitis is effective in the differential diagnosis of EoE and EC. Predominant cells in intraepithelial infiltrate are CD3+ T-lymphocytes both in EoE and RE, CD8+ cells prevail over CD4+ cells. In EoE intraepithelial count of CD3+ T-lymphocytes is 1.93 times more, count of intraepithelial CD4+ lymphocytes is 1.84 times more and count of CD8+ lymphocytes is 2.19 times more than in RE.

Assessment of the Severity and the Remission Criteria in Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is an immune-mediated disease that manifests with dysphagia and is characterized by the predominantly eosinophilic infiltration of the esophageal mucosa. Several instruments have been developed to assess the symptoms of EoE: the Daily Symptom Questionnaire (DSQ), EoE Activity Index (EEsAI), Pediatric EoE Symptom Severity (PEESSv2), etc. The use of the EREFS is a gold standard for endoscopic diagnosis. The EoE histologic scoring system (EoEHSS) was elaborated for the assessment of histological features in EoE. However, the remission criteria are not clearly defined and vary greatly in different studies. Gastroenterologists establish the severity of EoE mainly based on endoscopic findings. At the same time, EoE requires a multidisciplinary approach. The recently developed Index of Severity of Eosinophilic Esophagitis (I-SEE) that is built on symptoms, endoscopic findings, and histological features is promising.

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.

Eosinophilic esophagitis and esophageal microbiota

Eosinophilic esophagitis (EoE) is an antigen-mediated chronic inflammatory disease of the esophagus, the prevalence of which has steadily increased in recent years. The pathogenesis of EoE is not yet well-defined; however, recent studies have demonstrated that the esophageal microbiota is an essential regulator of physiological and pathological processes of EoE. Currently, research on EoE and microbiota is an emerging field of study that is receiving increasing attention. Here, we review existing EoE-related esophageal microbiota studies to explore the potential mechanisms underlying esophageal microbiota-mediated EoE. The esophageal microbiome is altered in patients with EoE. Although α diversity is usually not significantly different, an increase in Haemophilus and a decrease in Firmicutes were observed in EoE patients. The role of microbiota in initiating and perpetuating inflammation is not fully understood. Current evidence suggests that the penetration of microbiota leads to the activation of epithelial cells as well as innate and adaptive immune cells, with the subsequent release of cytokines, leading to immune responses and inflammation. The involvement of toll-like receptors in EoE also supports the potential role of the microbiota in the progression of this disease. While EoE-induced inflammation can also lead to alterations in the local microbiome. Moreover, dietary modifications, proton pump inhibitors, and corticosteroids can modulate the esophageal microbiota; however, definitive conclusions about the alterations of microbes after treatment cannot be drawn. These findings provide promising avenues for future studies.

Fecal Biomarkers of Neutrophil and Eosinophil Origin Reflect the Response to Biological Therapy and Corticosteroids in Patients With Inflammatory Bowel Disease

INTRODUCTION

Fecal calprotectin (FC) is a noninvasive tool for examining response to biologics in inflammatory bowel disease (IBD), but its performance in relation to other novel fecal markers of various cellular origins is unknown.

METHODS

We performed a prospective multicenter cohort study and included patients with active IBD who provided a fecal sample at initiation of biological therapy. Levels of FC, myeloperoxidase (MPO), human neutrophil lipocalin (HNL), and eosinophil-derived neurotoxin (EDN) were analyzed and related to clinical remission status at 3 months. Changes in levels of markers at 3 months were calculated, and the impact of concomitant use of corticosteroids at baseline was estimated.

RESULTS

In patients achieving clinical remission (n = 27), a decrease in levels of FC ( P = 0.005), MPO ( P < 0.001), HNL ( P < 0.001), and EDN ( P < 0.001) was observed, whereas no significant decrease was seen in patients not achieving remission (n = 39). There was a significant difference in the change in the level of MPO ( P = 0.01) and HNL ( P = 0.02) between patients achieving clinical remission and those who did not, but changes in FC and EDN could not differentiate between these groups. Patients with concomitant systemic corticosteroids at inclusion had lower levels of HNL ( P = 0.01) and EDN ( P < 0.001) at baseline, compared with patients without corticosteroids.

DISCUSSION

Fecal MPO, HNL, and EDN are all promising biomarkers for assessing the treatment outcome of biologics in patients with IBD. Fecal levels of EDN and HNL are significantly affected by corticosteroids indicating a greater sensitivity to the effects of corticosteroids compared with levels of FC and MPO.

Addressing educational gaps through multidisciplinary team education in eosinophilic oesophagitis management

Once considered a rare disease, eosinophilic oesophagitis (EoE) is becoming increasingly prevalent, yet many healthcare professionals (HCPs) remain unfamiliar with the underlying pathophysiology and optimal management approaches. For this study, we developed a faculty-led, online, continuing medical education activity on EoE. The effectiveness of this activity was evaluated according to Moore's framework, with changes in knowledge and competence (Moore's Levels 3 and 4) assessed for a cohort of gastroenterologists, dietitians, allergists and immunologists (N = 300), using questionnaires completed before and after participation. Changes in HCP confidence in treating EoE were also reported and remaining educational gaps were identified. The activity was viewed by a global audience of 5,330 participants within 6 months, and significant improvements in knowledge and competence were reported following participation in the activity across all specialities, regions and experience (mean [standard deviation] score pre- versus post-activity: 4.32 [1.38] versus 5.46 [0.82]; p < 0.001). Confidence in treating EoE also increased from pre- to post-activity, with the proportion of participants reporting that they felt moderately or extremely confident increasing from 53% to 82%. Several educational unmet needs were identified, which can be used to inform the design of future educational activities in EoE.

Novel corticosteroid formulations in the treatment of eosinophilic esophagitis: what is the evidence?

Background and study aims

Eosinophilic esophagitis (EoE) is a food allergen-induced disease of the esophagus. Chronic, eosinophil-predominant inflammation eventually leads to fibrosis, esophageal dysfunction and severe morbidity. Swallowed topical corticosteroids (STCs) are a mainstay of anti-inflammatory therapy in the treatment of active EoE. Data on the efficacy of novel corticosteroid formulations, developed specifically for esophageal delivery, have recently become available.

Methods

A comprehensive review was performed aiming to summarize evidence on the role of STCs in the treatment of EoE. Two biomedical bibliographic databases (PubMED, EMBASE) were searched for articles providing original information on the efficacy and safety of STCs in adult EoE patients.

Results

Budesonide orodispersible tablet (BOT) and budesonide oral suspension (BOS) both surpassed placebo formulations regarding the efficacy of inducing and maintaining histologic, symptomatic and endoscopic remission. Overall, BOT displayed the highest grade of efficacy with clinico-histologic remission rates up to 75% after 1 year. Fluticasone propionate (APT-1011) achieved and maintained histologic and endoscopic responses in the majority of patients, whereas only a positive trend was demonstrated for symptomatic improvement. Mometasone and ciclesonide were studied in a limited number of smaller-scale trials and placebo-controlled data are required to substantiate the promising findings. All STCs displayed a similar side effects profile and were generally considered safe and well-tolerated.

Conclusions

Current evidence supports long-term treatment with novel corticosteroid formulations, challenging the established treatment paradigm of EoE. BOT appears to be the most effective steroid therapy, although head-to-head comparative trials between STCs are needed.

Impact of environmental factors on the epidemiology of eosinophilic esophagitis in southwestern Europe (2007-2020)

Background

Eosinophilic esophagitis (EoE) is a disease characterized by symptoms of esophageal dysfunction and at least 15 eosinophils/hpf in the esophagus. Other systemic and local causes of esophageal eosinophilia should be excluded.

Objectives

The study objectives were to examine the annual epidemiology of EoE for 14 consecutive years, investigate whether there is a relationship between the count of aeroallergens and the incidence of EoE for 12 years, evaluate whether there are family ties between the patients with EoE, and determine whether there are cases of EoE that are triggered or exacerbated by pollens.

Methods

We conducted a prospective, descriptive, and analytic study in patients with EoE for 14 years (2007-2020). The study variables were age, sex, relatives with EoE, time of evolution of the symptoms until diagnosis of the disease, and symptoms. We examined incidence and prevalence, annual counts of aeroallergens for 12 years, and number of diagnoses per year (in 2007-2020). We studied patients with active EoE (in April-July) and EoE in remission (in August-March) for 2 consecutive years. Exacerbations were investigated by measuring symptoms using a visual analog scale of 1 to 10.

Results

Of the 366 patients with EoE (studied from 2007 to 2020), 83.5% were atopic, with respiratory allergy and 28% had a food allergy. Their mean age was 35 years. The time of evolution of the symptoms was more than 6 years. Only 11% of the patients had a degree of kinship. Of the 366 patients, 87% had dysphagia, 27% had had impactions, and 12.5% had other symptoms of esophageal dysfunction. We found a positive correlation between the incidence of EoE and Platanaceae pollens. We did not detect any case of EoE triggered or exacerbated by pollens.

Conclusions

The epidemiology of EoE in southwestern Europe continues to grow. We have corroborated the relevant impact of the environment on genetics. Future studies will clarify the possible relevance of Platanaceae pollens in the increased epidemiology of EoE. The role of grass and Oleaceae pollens in triggering EoE is limited by having a short pollination in time.

Eosinophilic Airway Diseases: From Pathophysiological Mechanisms to Clinical Practice

Eosinophils play a key role in airway inflammation in many diseases, such as allergic and non-allergic asthma, chronic rhinosinusitis with nasal polyps, and chronic obstructive pulmonary disease. In these chronic disabling conditions, eosinophils contribute to tissue damage, repair, remodeling, and disease persistence through the production a variety of mediators. With the introduction of biological drugs for the treatment of these respiratory diseases, the classification of patients based on clinical characteristics (phenotype) and pathobiological mechanisms (endotype) has become mandatory. This need is particularly evident in severe asthma, where, despite the great scientific efforts to understand the immunological pathways underlying clinical phenotypes, the identification of specific biomarkers defining endotypes or predicting pharmacological response remains unsatisfied. In addition, a significant heterogeneity also exists among patients with other airway diseases. In this review, we describe some of the immunological differences in eosinophilic airway inflammation associated with severe asthma and other airway diseases and how these factors might influence the clinical presentation, with the aim of clarifying when eosinophils play a key pathogenic role and, therefore, represent the preferred therapeutic target.

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.

Blood and adipose-resident eosinophils are defined by distinct transcriptional profiles

Eosinophils are granular leukocytes of the innate immune system that play important functions in host defense. Inappropriate activation of eosinophils can occur in pathologies such as asthma and esophagitis. However, eosinophils also reside within adipose tissue, where they play homeostatic roles and are important in the activation of thermogenic beige fat. Here we performed bulk RNA sequencing in mouse adipose tissue-resident eosinophils isolated from both subcutaneous and gonadal depots, for the first time, and compared gene expression to blood eosinophils. We found a predominantly conserved transcriptional landscape in eosinophils between adipose depots that is distinct from blood eosinophils in circulation. Through exploration of differentially expressed transcription factors and transcription factors with binding sites enriched in adipose-resident eosinophil genes, we identified KLF, CEBP, and Fos/Jun family members that may drive functional specialization of eosinophils in adipose tissue. These findings increase our understanding of tissue-specific eosinophil heterogeneity, with implications for targeting eosinophil function to treat metabolic disorders such as obesity.

The Gut Microbiome and Its Implication in the Mucosal Digestive Disorders

The gastrointestinal (GI) tract is one of the most studied compartments of the human body as it hosts the largest microbial community including trillions of germs. The relationship between the human and its associated flora is complex, as the microbiome plays an important role in nutrition, metabolism and immune function. With a dynamic composition, influenced by many intrinsic and extrinsic factors, there is an equilibrium maintained in the composition of GI microbiota, translated as "eubiosis". Any disruption of the microbiota leads to the development of different local and systemic diseases. This article reviews the human GI microbiome's composition and function in healthy individuals as well as its involvement in the pathogenesis of different digestive disorders. It also highlights the possibility to consider flora manipulation a therapeutic option when treating GI diseases.

Therapeutical Targets in Allergic Inflammation

From the discovery of IgE to the in-depth characterization of Th2 cells and ILC2, allergic inflammation has been extensively addressed to find potential therapeutical targets. To date, omalizumab, an anti-IgE monoclonal antibody, and dupilumab, an anti-IL-4 receptor α monoclonal antibody, represent two pillars of biologic therapy of allergic inflammation. Their increasing indications and long-term follow-up studies are shaping the many different faces of allergy. At the same time, their limitations are showing the intricate pathogenesis of allergic diseases.

Eosinophils in the Gastrointestinal Tract: Key Contributors to Neuro-Immune Crosstalk and Potential Implications in Disorders of Brain-Gut Interaction

Eosinophils are innate immune granulocytes actively involved in defensive responses and in local and systemic inflammatory processes. Beyond these effector roles, eosinophils are fundamental to maintaining homeostasis in the tissues they reside. Gastrointestinal eosinophils modulate barrier function and mucosal immunity and promote tissue development through their direct communication with almost every cellular component. This is possible thanks to the variety of receptors they express and the bioactive molecules they store and release, including cytotoxic proteins, cytokines, growth factors, and neuropeptides and neurotrophines. A growing body of evidence points to the eosinophil as a key neuro-immune player in the regulation of gastrointestinal function, with potential implications in pathophysiological processes. Eosinophil–neuron interactions are facilitated by chemotaxis and adhesion molecules, and the mediators released may have excitatory or inhibitory effects on each cell type, with physiological consequences dependent on the type of innervation involved. Of special interest are the disorders of the brain–gut interaction (DBGIs), mainly functional dyspepsia (FD) and irritable bowel syndrome (IBS), in which mucosal eosinophilia and eosinophil activation have been identified. In this review, we summarize the main roles of gastrointestinal eosinophils in supporting gut homeostasis and the evidence available on eosinophil–neuron interactions to bring new insights that support the fundamental role of this neuro-immune crosstalk in maintaining gut health and contributing to the pathophysiology of DBGIs.