Eosinophilic esophagitis and symptoms possibly related to eosinophilic esophagitis in oral immunotherapy

The ethics of food allergy

PURPOSE OF REVIEW

Ethical dilemmas are a common occurrence in the provision of care to individuals with food allergies. Thus, an understanding of medical ethics is essential for allergists/immunologists.

RECENT FINDINGS

Despite the importance of medical ethics in the clinical practice of food allergy, there has been little published on this topic. Some international allergy societies have published ethical guidelines. Further investigation on medical ethics in food allergy is required.

SUMMARY

This review describes key ethical principles in relation to food allergy testing, oral food challenges, and various management strategies, including avoidance, omalizumab and oral immunotherapy. This review demonstrates the necessity for education and research on medical ethics in food allergy.

Oral Immunotherapy Should Play a Key Role in Preschool Food Allergy Management

Food allergies pose significant challenges including the risk for severe allergic reactions. This review article highlights the advantages and disadvantages of the historic standard management approach-avoidance and carrying epinephrine in case of accidental ingestion-and argues, based on accumulating evidence, that oral immunotherapy (OIT) should play a key role in preschool food allergy management. Firstly, our review will highlight pitfalls with the 'wait-and-see' approach to natural resolution of food allergies, with recent data pointing to lower resolution than previously thought. For those who do not outgrow their allergies, waiting until school age to offer OIT means missing the window of opportunity where OIT is safest, and prolongs unnecessary dietary restrictions. For those who do outgrow their allergies, research indicates they may not reintroduce the food due to fear and aversion and can become re-sensitised, putting them at risk of severe reactions. Secondly, the risks associated with allergen avoidance are higher than previously believed. Allergen avoidance is imperfect and carries an increased risk of severe reactions when compared with the risk of severe reactions while on OIT, particularly in preschoolers. Although an allergic reaction can be stressful, it is preferable to have this occur during OIT where caregivers are vigilant following a scheduled dose, rather than having this occur at a potentially unexpected time following an accidental exposure. Lastly, there is a growing body of evidence supporting favourable safety and effectiveness of OIT in preschoolers, and preliminary data suggesting higher likelihood of remission in infants. OIT has the potential to significantly improve quality of life, and future research is needed to answer this important question in preschoolers. In summary, while ongoing research will further clarify cost-effectiveness, long-term adherence and psychosocial impacts of OIT, this review suggests that OIT should play a key role in preschool food allergy management.

Allergen immunotherapy and eosinophilic esophagitis: friends or foes?

PURPOSE OF REVIEW

The connection between eosinophilic esophagitis (EoE) and food and airborne allergens is complex. Exposure to allergens (mainly food) is often the trigger for EoE flares. The development of EoE has been described as a side effect of allergen immunotherapy, especially oral immunotherapy (OIT, with food allergens), while isolated cases of EoE have been reported during sublingual immunotherapy (SLIT, with extracts of aeroallergens).

RECENT FINDINGS

EoE is currently recognized as a common side effect of OIT, while a solid correlation between SLIT and EoE is missing. Animal models have been developed to study the pathophysiological link between sensitization to aeroallergens and the induction of EoE and will probably provide an interpretation of why there are cases of EoE developed during SLIT. Recent findings in animal models suggest a genetic connection to EoE development after sensitization and re-exposure to airborne allergens. Subcutaneous allergen immunotherapy does not have a causative effect on EoE; on the contrary, a beneficial effect on EoE has been reported. Moreover, epicutaneous immunotherapy with a vector containing milk has also been used to treat children with milk-induced EoE.

SUMMARY

Discovering the immune links between allergens and EoE will further guide the proper use of allergen immunotherapy and help define future strategies for the management of EoE.

Outcomes of apple oral immunotherapy in pollen food allergy syndrome

Oral immunotherapy with apple induces tolerance for an entire apple (128 g) in patients with pollen food allergy syndrome who previously tolerated a median amount of 4 g of apple.

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.

Associations of Eosinophilic Gastrointestinal Disorders with Other Gastrointestinal and Allergic Diseases

Eosinophilic gastrointestinal disorders (EGIDs) are becoming more common causing significant suffering and reduced quality of life. These conditions can affect different parts of the digestive system, either individually or in combination. Recognition of their link to allergic disorders or other gastrointestinal (GI) diseases has raised questions about their shared underlying mechanisms, which has had implications for diagnosis and management. The authors critically examine the current understanding of the connection between EGIDs and allergic conditions (ie, atopic dermatitis, allergic rhinitis, asthma, and food allergy) and GI diseases (ie, inflammatory bowel disease, celiac disease, gastroesophageal reflux disease, and motility disorders).

The Relationship Between Eosinophilic Esophagitis and Immunotherapy

Immunotherapy is a treatment approach based on the principle of incremental allergen exposure to achieve desensitization. Recently, oral immunotherapy has been introduced as a treatment of IgE-mediated food allergy. Some patients receiving oral immunotherapy for food allergy may develop eosinophilic esophagitis. Here, we summarize the literature examining this association, its treatment, and outcomes and discuss possible explanations for this clinical phenomenon. We further identify potential associations with aeroallergen sensitivity and other forms of immunotherapy including subcutaneous immunotherapy and sublingual immunotherapy. Finally, we discuss management of immunotherapy-induced eosinophilic esophagitis. Epicutaneous immunotherapy is highlighted as an area of therapeutic investigation.

Clinical Evaluation of the Child with Eosinophilic Esophagitis

The diagnosis of eosinophilic esophagitis (EoE) is based on clinical symptoms of esophageal dysfunction and eosinophil predominant esophageal inflammation. Clinical symptoms in children with EoE vary based on age and may be nonspecific. EoE has a male predominance with the majority having comorbid atopic disorders. At present, treatment options include medications (proton pump inhibition, swallowed topical steroids), dietary therapy or biologic therapy (dupilumab, approved for those ≥12 years of age). Outside of EoE in the context of oral immunotherapy, EoE is typically chronic requiring lifelong therapy. Long-term complications including feeding difficulties, malnutrition, and fibrostenotic disease.

Implementing Food Oral Immunotherapy Into Clinical Practice: Quality and Safety Perspectives From a US Academic Center

Oral immunotherapy (OIT) is an accessible procedure for practicing allergy/immunology providers, yet rigorous safety standards are limited in the clinical setting. By exploring the transition from research to clinical practice OIT, we review relevant safety considerations necessary for the clinical provider. We offer a perspective on clinical benefits and considerations at the individual, collaboration, and policy levels from the vantage of a large academic OIT program, and we propose several practical start-up checklists and clerical considerations for practicing providers. Awareness of the local population and front-end planning is necessary to improve the accessibility of this procedure in clinical practice among racial and socioeconomic minority populations. Sharing and merging OIT protocols, procedural methods, and electronic medical record order sets may increase harmonization among OIT-providing institutions and further our abilities to pool safety and outcomes data, ultimately enhancing the safety and efficacy of clinical OIT.

The Future of Food Allergy Management: Advancements in Therapies

PURPOSE OF REVIEW

To review current and future treatment options for IgE-mediated food allergy.

RECENT FINDINGS

Recent years have seen major developments in both allergen-specific and allergen-non-specific treatment options, with the first FDA-approved peanut oral immunotherapy (OIT) product becoming available in 2020. In addition to OIT, other immunotherapy modalities, biologics, adjunct therapies, and novel therapeutics are under investigation. Food allergy is a potentially life-threatening condition associated with a significant psychosocial impact. Numerous products and protocols are under investigation, with most studies focusing on OIT. A high rate of adverse events, need for frequent office visits, and cost remain challenges with OIT. Further work is needed to unify outcome measures, develop treatment protocols that minimize adverse events, establish demographic and clinical factors that influence candidate selection, and identify patient priorities.

Epidemiology and the Growing Epidemic of Food Allergy in Children and Adults Across the Globe

PURPOSE OF REVIEW

Food allergies are immune-mediated, complex disorders, which are the source of increasing health concern worldwide. The goal of this review is to present an updated summary of the food allergy (FA) burden among children and adults across different populations, focusing on research from the past 5 years.

RECENT FINDINGS

FAs impact a growing number of global residents-particularly those residing in higher-income, industrialized regions. Moreover, growing epidemiologic evidence suggests that the population health burden of non-IgE-mediated FAs, such as food protein-induced enterocolitis syndrome, may also be higher than previously reported. FA is a complex trait that impacts infants, children, as well as adults across the globe. The population health burden of both IgE- and non-IgE-mediated FAs is likely to grow in the absence of rapid advances and widespread implementation of effective FA prevention and treatment interventions. Systematic epidemiological research initiatives are needed, both nationally and globally, to better understand and reduce the burden of these allergic diseases.

Eosinophil-Associated Gastrointestinal Manifestations During OIT

Gastrointestinal adverse events are common during oral immunotherapy (OIT) for food allergy and range from immediate IgE-mediated reactions to non-anaphylactic clinical presentations. This review aims to summarize recent findings on non-anaphylactic eosinophil-associated gastrointestinal adverse events during OIT. Two clinical presentations of non-anaphylactic eosinophil-associated gastrointestinal adverse events during OIT are identified, each with a different paradigm for treatment, and distinguished by their time of onset. In the first clinical entity, characterized by its onset early in the course of treatment, patients present with abdominal pain, nausea, and/or vomiting. The symptoms become evident typically within weeks to months of starting OIT. These symptoms, however, are not temporally related to the time of dose administration, as in the case of immediate IgE-mediated anaphylactic reactions. While esophageal biopsies, when performed, can demonstrate eosinophilic esophagitis (EoE), baseline esophageal eosinophilia has also been observed in food allergic patients prior to OIT. A potential non-invasive biomarker, the peripheral absolute eosinophil count (AEC), often rises during these reactions and subsides after dose reduction and subsequent resolution of symptoms. OIT can usually then be resumed, albeit at a slower pace, without a recurrence of symptoms. Risk factors for development of symptoms early during OIT include a high starting dose and a baseline AEC of greater than 600. The second, and much less frequently encountered, non-anaphylactic gastrointestinal adverse event related to OIT, presents months to years after initiating OIT. In this latter group, patients present with the classical clinical symptoms and endoscopic findings of EoE. In contrast to the acute onset group, peripheral eosinophilia is usually not observed in these cases. This OIT-associated EoE has shown good response to standard EoE treatment approaches of proton pump inhibitors or swallowed steroids. Most patients with eosinophil-associated adverse reactions are able to continue OIT and remain desensitized. Treatment approaches depend on the specific subtype of these reactions and relate to the stages of OIT treatment.

Breakthroughs in understanding and treating eosinophilic gastrointestinal diseases presented at the CEGIR/TIGERs Symposium at the 2022 American Academy of Allergy, Asthma & Immunology Meeting

The Consortium of Eosinophilic Gastrointestinal Diseases and The International Gastrointestinal Eosinophil Researchers organized a day-long symposium at the 2022 Annual Meeting of the American Academy of Allergy, Asthma & Immunology. The symposium featured a review of recent discoveries in the basic biology and pathogenesis of eosinophilic gastrointestinal diseases (EGIDs) in addition to advances in our understanding of the clinical features of EGIDs. Diagnostic and management approaches were reviewed and debated, and clinical trials of emerging therapies were highlighted. Herein, we briefly summarize the breakthrough discoveries in EGIDs.

Ethical Implications of Continuing Oral Immunotherapy After the Development of Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic allergic inflammatory disease requiring maintenance therapy. Traditionally, EoE has been a contraindication to oral immunotherapy (OIT) and a rationale for discontinuing treatment because OIT may induce EoE. Most, but not all patients with OIT-induced EoE experience symptom resolution and histologic remission after discontinuing OIT. Recent studies report OIT continuation even after EoE onset, despite the previously accepted standard of care. This creates clinical as well as ethical challenges for allergists treating these patients. Considering the published literature on EoE and OIT and the primary medical ethics principles of beneficence, nonmaleficence, autonomy, and justice, we discuss the ethical implications of pursuing desensitization despite the potential complications associated with EoE. When ethical principles are in opposition, shared decision-making should be employed to determine whether OIT should be continued after an EoE diagnosis. This article highlights the ethical dilemmas allergists face when determining whether patients with a diagnosis of EoE should continue OIT.

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.

A case of food and aeroallergen sublingual immunotherapy inducing eosinophilic esophagitis

Eosinophilic esophagitis (EoE) has been reported secondary to aeroallergen sublingual immunotherapy (SLIT) and food allergen oral immunotherapy. Gastrointestinal symptoms with food allergen SLIT are uncommon, with no prior reports of cases of food allergen SLIT inducing EoE. Here we report a patient who developed EoE secondary to food and aeroallergen SLIT therapy that resolved with SLIT cessation.

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.

Oral Immunotherapy and Risk of Eosinophilic Esophagitis in Children: 15 Years' Experience

OBJECTIVES

Oral immunotherapy (OIT) is an effective treatment for children with persistent food allergy, and has concerns about its safety, including eosinophilic esophagitis (EoE). The aim of this study was to evaluate the prevalence of EoE in a large cohort of children who underwent OIT in our center, and to determine if there were any clinical, endoscopic, or histologic differences depending on the food employed for the OIT.

METHODS

A retrospective study was performed over a 15-year period (2005-2020). Children who underwent cow's milk (CM), egg, and/or peanut OIT and developed EoE were included.

RESULTS

Six hundred and seven OIT were carried out (277 CM-OIT, 322 egg-OIT, and 8 peanut-OIT). Seventeen patients (2.8%) had a confirmed histologic diagnosis of EoE with a higher prevalence for patients who underwent CM-OIT (3.9%) than egg-OIT (2.2%). Symptoms suggestive of EoE and a confirmed diagnosis occurred at median times of 25 and 36 months, respectively, after the build-up phase of the OIT was completed. Choking, abdominal pain, and dysphagia were the most frequent symptoms and lamina propria fibrosis was observed in 41.2% of patients. No significant differences in clinical symptoms, endoscopic, or histologic findings between patients under CM or egg-OIT were found. One-third of patients reported mild symptoms suggestive of EoE before the OIT.

CONCLUSIONS

EoE appears to be a rare but important adverse event that can occur even years after OIT. Validated questionnaires to screen EoE before the OIT and in the follow-up of these patients may be the main tool for an early diagnosis.

Eosinophilic Gastrointestinal Diseases: The Pathogenesis, Diagnosis, and Treatment

Eosinophilic gastrointestinal diseases are delayed-type chronic allergic disorders that show gastrointestinal eosinophil dense infiltration, with an exaggerated Th2-type immune reaction considered to be an important mechanism. These diseases can be roughly divided into two types: eosinophilic esophagitis, mainly found in young and middle-aged men, and eosinophilic gastroenteritis, which is found in both genders equally. A diagnosis of eosinophilic esophagitis is suspected when characteristic endoscopic findings, including longitudinal furrows and rings, are noted. However, characteristic endoscopic abnormalities are rarely found in cases with eosinophilic gastroenteritis, so multiple biopsy sampling from the apparently normal gastrointestinal mucosal surface is important for making an accurate diagnosis. The administration of systemic glucocorticoid is the standard treatment for eosinophilic gastroenteritis, while acid inhibitors and topical glucocorticoid swallowing therapy are effective for eosinophilic esophagitis. Anti-cytokine therapies for eosinophilic gastrointestinal diseases are currently under development.

How We Manage Gastrointestinal Symptoms During Oral Immunotherapy Through a Shared Decision-Making Process-A Practical Guide for the Community Practitioner

Allergists addressing gastrointestinal (GI) symptoms during oral immunotherapy (OIT) may be biased toward diagnoses related to OIT; however, non-OIT causes may occur. Although there is currently a lack of robust data for evidence-based treatment recommendations, we provide 3 real-world illustrative cases along with a proposed management algorithm for GI symptoms encountered during OIT. This algorithm was developed because of a significant clinical need, given the number of new-to-OIT providers that include practicing allergists, trainees transitioning into practice, and allied health care providers who manage GI symptoms in OIT patients. We developed the algorithm based on the opinions of community and academic allergy clinics across Canada with significant clinical experience offering infant, preschool, and school-aged OIT patients, with gastroenterologist input. Further research is needed to fill the knowledge gaps in the management of GI symptoms during OIT before formal recommendations can be suggested.

Oesophageal secretions reveal local food-specific antibody responses in eosinophilic oesophagitis

BACKGROUND

Eosinophilic oesophagitis (EoE) is associated with elevated IgG4 in oesophageal tissue and serum. Previously, we showed brush-collected oesophageal secretions of EoE patients contained food antigen-specific antibodies IgA and IgG4. It is unknown whether other food-specific antibodies are present along the surface of the oesophagus in EoE.

AIM

To identify whether immunoglobulins other than IgG4 and food-specific antibodies are elevated along the oesophageal mucosal surface in oesophageal secretions in EoE patients METHODS: Concentrations of total IgA, IgG1, IgG2, IgG3, IgG4, IgM and IgE were measured in oesophageal secretions from patients with active (n = 19) and inactive EoE (n = 9), and non-EoE controls (n = 10). Food-specific antibodies were measured using beads coupled to protein components from dairy, wheat and egg. Total immunoglobulin and cytokine and chemokine concentrations were measured in serum, saliva and oesophageal secretions of four patients with active EoE.

RESULTS

Oesophageal secretions have a unique immune profile. Patients with active EoE had elevated IgG2, IgG4 and IgM concentrations in oesophageal secretions compared to those with inactive EoE. Food-specific IgG1, IgG2, IgG4 and IgM were significantly increased in patients with active EoE compared to inactive EoE and non-EoE patients. Furthermore, active patients with a known dairy trigger display higher dairy-specific IgG1, IgG2, IgG4, IgM, IgA and IgE.

CONCLUSIONS

There is a distinct localised profile of immunoglobulins and food-specific antibodies found within oesophageal secretions in EoE. These findings expand our knowledge about the currently identified immune responses in EoE and suggest possible roles for multiple immunoglobulins and food-specific antibodies in the pathophysiology of EoE.

A review of the safety of oral immunotherapy in clinical trial and real-world studies

Safety concerns are a barrier to oral immunotherapy (OIT). This review aims to describe OIT safety events and explore potential risk factors and mitigating factors. Published clinical and real-world OIT studies were reviewed for data on safety outcomes in OIT. Gastrointestinal symptoms are one of the most common adverse reactions associated with OIT, and persistent symptoms can be associated with an eosinophilic response. Allergic reactions are increased in OIT compared with avoidance; however, these symptoms tend not to be severe and to decrease over time. Despite OIT, epinephrine usage persists in studies and life-threatening reactions (though rare) have occurred. High baseline food specific immunoglobulin E levels, aggressive dosing, uncontrolled atopic comorbidities, and poor adherence to protocols may contribute to the severity of adverse events. OIT remains a shared decision that incorporates best medical evidence and appropriate patient selection. It requires individualized care and action plans to ensure safe outcomes.

Considerations for a shared decision-making conversation when initiating food oral immunotherapy

Oral immunotherapy (OIT) is an office-based procedure that offers potential treatment of immunoglobulin E mediated food allergy. OIT has multiple benefits, e.g., the ability to desensitize the individual with food allergy, which shifts the eliciting dose threshold required in that individual to trigger an allergic reaction, and also potentially to decrease the severity of any resulting reactions. However, OIT is not a cure and has distinct risks, including the risk of allergic reactions (including anaphylaxis) from the therapy itself, the potential risk of developing eosinophilic esophagitis (or similar clinical symptoms without a formal biopsy), and logistical issues in coordinating when to give the daily dose, and there are still uncertain intermediate-to-long-term outcomes with regard to OIT. The decision to start OIT is complex and potentially nuanced. Shared decision-making is a process that allows the patient and family and the clinician to undergo a mutual discussion of the risks, benefits, alternatives, and other considerations with regard to a medical decision (such as starting OIT) whereby there is an exchange of information that allows the patient and family to formally clarify and express their values and preferences with regard to facets of the decision in this particular context. The goal is for the patient to be able to make a fully informed decision that is reflective of his or her goals, values, preferences, and desires. This article outlined some of the key considerations to discuss with parents and patients before enrolling in an OIT program with regard to the risks and benefits, to assist in engaging in shared decision-making and obtaining informed consent.

A practical focus on wheat oral immunotherapy

Wheat is a dietary staple in many cultures as well as a common food allergen. Although not as extensively studied as other forms of oral immunotherapy, the current literature suggests that wheat oral immunotherapy (WOIT) can result in successful desensitization. There has only been one multicenter, double-blind, randomized controlled trial of WOIT, along with several open-label nonrandomized trials. The trials were limited by several factors, including small sample sizes; demographic skew; and heterogeneity in dosing, duration, and outcomes. The majority of WOIT regimens results in desensitization, with literature that indicates that a longer duration and higher dosing may lead to more clinical success. WOIT has been associated with adverse events, including allergic reactions, but these events seem to decrease over time. Study on WOIT is underway, but evidence from trials suggests it can be successful and safe. Further studies will need to optimize dosing protocols to improve efficacy and safety.

Guided Gradual Egg-Tolerance Induction in Hen's Egg Allergic Children Tolerating Baked Egg: A Prospective Randomized Trial

Background

Over the last few years, studies have shown that the majority of egg allergic children tolerate baked egg (e.g., cake), and that consuming baked egg accelerates the resolution of egg allergy. However, few prospective studies demonstrate the step-wise reintroduction of egg at home after developing baked egg tolerance. Although this could have a positive impact on the children's quality of life and nutrition. Additionally, research supporting the theoretical concept that heating in the presence or absence of wheat causes reduced allergenicity of egg proteins is limited.

Objective

To investigate the clinically most favorable duration of gradual egg-tolerance induction in baked egg tolerant children at home, with regard to complete raw egg tolerance.

Methods

Baked egg tolerant children above 12 months of age were randomly assigned to a short- or long arm protocol. In the short arm, egg-tolerance induction was studied over 18 months compared to 30 months in the long arm. Children were guided through this protocol involving the step-wise introduction of increasingly allergenic forms of egg starting with baked egg offered as cake, followed by hard-boiled egg, omelet/waffle/pancake, soft-boiled egg, and finally raw egg. We hereby designed this protocol based on the influence of thermal processing in the presence or absence of wheat on egg proteins, as investigated by ELISA, SDS-PAGE, and immunoblotting. At inclusion, children either passed an in-hospital cake challenge or had ovomucoid sIgE ≤1.2 kUA/L, which was considered safe for introduction at home.

Results

Gel electrophoresis revealed that the ovalbumin band became weaker with heating, while the ovomucoid band remained stable. In accordance, the IgE-binding to ovalbumin decreased with extensive heating, as opposed to ovomucoid. However, heating in the presence of wheat led to a decreased IgE reactivity to ovomucoid. Of the 78 children in the intention-to-treat group, 39 were randomized to each arm. Fifty-eight children reached the raw egg tolerance endpoint, of which 80% were in the short arm and 69% in the long arm. Within the short arm, the median time to raw egg tolerance was 24 months (95% CI, 21–27 months) compared to 30 months (95% CI, 28–32 months) in the long arm (p = 0.005). No grade IV reactions or cases of eosinophilic esophagitis were observed. The short arm was considered to be non-inferior to the long arm.

Conclusion

Our gradual short arm protocol appears to be safe and allows clinicians to guide baked egg tolerant children toward raw egg tolerance at home. The allergenicity of the egg proteins was affected by heating temperature and duration, as well as the presence of wheat.

Probiotic peanut oral immunotherapy versus oral immunotherapy and placebo in children with peanut allergy in Australia (PPOIT-003): a multicentre, randomised, phase 2b trial

BACKGROUND

Oral immunotherapy is effective at inducing desensitisation to allergens and induces sustained unresponsiveness (ie, clinical remission) in a subset of patients, but causes frequent reactions. We aimed to investigate whether addition of a probiotic adjuvant improved the efficacy or safety of peanut oral immunotherapy.

METHODS

PPOIT-003, a multicentre, randomised, phase 2b trial, was conducted in three tertiary hospitals in Australia (Adelaide [SA], Melbourne [VIC], and Perth [WA]) in children aged 1-10 years, weighing more than 7 kg, with peanut allergy confirmed by a double-blind placebo-controlled food challenge (cumulative 4950 mg dose of peanut protein) and positive peanut skin prick test (≥3 mm) or peanut-specific IgE (≥0·35 kU/L). Children were randomly assigned (2:2:1) to receive probiotic and peanut oral immunotherapy (PPOIT), placebo probiotic and peanut oral immunotherapy (OIT), or placebo probiotic and placebo OIT (placebo) for 18 months, and were followed up until 12 months after completion of treatment. Oral immunotherapy consisted of increasing doses of peanut protein (commercially available food-grade 12% defatted peanut flour [50% peanut protein]) until a 2000 mg daily maintenance dose was reached. The probiotic adjuvant was a daily dose of 2 × 10¹⁰ colony-forming units of the probiotic Lactobacillus rhamnosus ATCC 53103. Placebo immunotherapy comprised maltodextrin, brown food colouring, and peanut essence, and placebo probiotic was maltodextrin. Dual primary outcomes were 8-week sustained unresponsiveness, defined as no reaction to a cumulative dose of 4950 mg peanut protein at treatment completion and 8 weeks after treatment completion, in the PPOIT versus placebo groups and the PPOIT versus OIT groups, analysed by intention to treat. Safety endpoints were adverse events during the treatment phase, and peanut ingestion and reactions in the 12-month post-treatment period. This study is registered with the Australian New Zealand Clinical Trials Registry, 12616000322437.

FINDINGS

Between July 4, 2016, and Sept 21, 2020, 201 participants were enrolled and included in the intention-to-treat analysis. 36 (46%) of 79 children in the PPOIT group and 42 (51%) of 83 children in the OIT group achieved sustained unresponsiveness compared with two (5%) of 39 children in the placebo group (risk difference 40·44% [95% CI 27·46 to 53·42] for PPOIT vs placebo, p<0·0001), with no difference between PPOIT and OIT (-5·03% [-20·40 to 10·34], p=0·52). Treatment-related adverse events were reported in 72 (91%) of 79 children in the PPOIT group, 73 (88%) of 83 children in the OIT group, and 28 (72%) of 39 children in the placebo group. Exposure-adjusted incidence of adverse events was 10·58 in the PPOIT group, 11·36 in the OIT, and 2·09 in the placebo group (ratio 0·92 [95% CI 0·85 to 0·99] for PPOIT vs OIT, p=0·042; 4·98 [4·11-6·03] for PPOIT vs placebo, p<0·0001; 5·42 [4·48-6·56] for OIT vs placebo, p<0·0001), with differences seen primarily in gastrointestinal symptoms and in children aged 1-5 years. During the 12-month post-treatment period, 60 (85%) of 71 participants in the PPOIT group, 60 (86%) of 70 participants in the OIT group, and six (18%) of 34 participants in the placebo group were eating peanut; rescue epinephrine use was infrequent (two [3%] of 71 in the PPOIT group, four [6%] of 70 in the OIT group, and none in the placebo group).

INTERPRETATION

Both PPOIT and OIT were effective at inducing sustained unresponsiveness. Addition of a probiotic did not improve efficacy of OIT, but might offer a safety benefit compared with OIT alone, particularly in preschool children.

FUNDING

National Health and Medical Research Council Australia and Prota Therapeutics.

Advances, Practical Implementation, and Unmet Needs Regarding Oral Immunotherapy for Food Allergy

Treatment of food allergy is a rapidly changing landscape, with arguably, the most significant advancement in recent years, the transition of oral immunotherapy (OIT) to clinical practice. As an innovation, OIT is a phase of rapidly increasing demand, particularly for some allergens such as peanut, egg, and milk, which have substantial evidence of efficacy. However, significant questions remain about how to best treat multiple food allergies and less common food allergies and how to optimize long-term safety and efficacy. This review summarizes the currently available resources for integrating food allergy OIT into clinical practice and focuses on the multiple remaining unmet needs such as providing an approach for OIT to food allergens for which there is no or limited evidence; practical issues related to food allergy treatment particularly when it is not going well; long-term outcomes and follow-up after OIT; and strategies to help meet the impending increase in demand.

Efficacy and Safety of Baked Milk Oral Immunotherapy in Children with Severe Milk Allergy: A Randomized, Double-blind, Placebo-controlled Phase 2 Trial

BACKGROUND

Cow's milk allergy is the most common food allergy in young children and has no current treatment. Oral immunotherapy studies to date have shown efficacy but high rates of adverse reactions.

OBJECTIVE

We sought to evaluate the safety and efficacy of baked milk oral immunotherapy (BMOIT) in baked milk allergic children.

METHODS

Participants (3-18 years) were randomized to receive BMOIT or placebo for 12 months. Efficacy was assessed by double-blind placebo-controlled food challenge after 12 months of treatment. Safety, quality of life, and mechanistic parameters were also evaluated.

RESULTS

11/15 (73%) of the BMOIT participants reached the primary endpoint, tolerating 4044 mg of baked milk protein after 12 months of OIT, compared to 0/15 (0%) on placebo. The median maximal tolerated dose (MTD) and median change from baseline was significantly higher in the BMOIT group compared to placebo (median MTD 4044mg vs 144mg; p=0.001; median change in MTD of 3900mg vs 0mg, p=0.0001). Dose-related reactions were common but >95% in both groups were mild. There was no significant change in CM- or beta lactoglobulin-IgE from baseline for either group. CM-sIgG4 did significantly increase and casein IgE decreased in the BMOIT group. For proxy-reported food allergy quality of life, there was a significant difference in the emotional impact domain only with more improving while on placebo compared BMOIT. The majority of children and adolescents in the BMOIT group directly reported improvement in at least one domain.

CONCLUSION

BMOIT was well tolerated and induced a substantial level of desensitization after 12 months of treatment.

Esophageal Eosinophilia and Eosinophilic Esophagitis in Celiac Children: A Ten Year Prospective Observational Study

The association between eosinophilic esophagitis and celiac disease is still controversial and its prevalence is highly variable. We aimed to investigate the prevalence of esophageal eosinophilia and eosinophilic esophagitis in a large group of children with celiac disease, prospectively followed over 11 years.

METHODS

Prospective observational study performed between 2008 and 2019. Celiac disease diagnosis was based on ESPGHAN criteria. At least four esophageal biopsies were sampled in patients who underwent endoscopy. The presence of at least 15 eosinophils/HPF on esophageal biopsies was considered suggestive of esophageal eosinophilia; at the same time, eosinophilic esophagitis was diagnosed according to the International Consensus Diagnostic Criteria for Eosinophilic Esophagitis.

RESULTS

A total of 465 children (M 42% mean age 7.1 years (range: 1-16)) were diagnosed with celiac disease. Three hundred and seventy patients underwent endoscopy, and esophageal biopsies were available in 313. The prevalence of esophageal eosinophilia in children with celiac disease was 1.6% (95% CI: 0.54-2.9%). Only one child was diagnosed as eosinophilic esophagitis; we calculated a prevalence of 0.3% (95% CI: 0.2-0.5%). The odds ratio for an association between eosinophilic esophagitis and celiac disease was at least 6.5 times higher (95% CI: 0.89-47.7%; p = 0.06) than in the general population.

CONCLUSION

The finding of an increased number of eosinophils (>15/HPF) in celiac patients does not have a clinical implication or warrant intervention, and therefore we do not recommend routine esophageal biopsies unless clinically indicated.

Oral Immunotherapy for Food-Allergic Children: A Pro-Con Debate

The prevalence of food allergy has increased in recent years, especially in children. Allergen avoidance, and drugs in case of an allergic reaction, remains the standard of care in food allergy. Nevertheless, increasing attention has been given to the possibility to treat food allergy, through immunotherapy, particularly oral immunotherapy (OIT). Several OIT protocols and clinical trials have been published. Most of them focus on children allergic to milk, egg, or peanut, although recent studies developed protocols for other foods, such as wheat and different nuts. OIT efficacy in randomized controlled trials is usually evaluated as the possibility for patients to achieve desensitization through the consumption of an increasing amount of a food allergen, while the issue of a possible long-term sustained unresponsiveness has not been completely addressed. Here, we evaluated current pediatric OIT knowledge, focusing on the results of clinical trials and current guidelines. Specifically, we wanted to highlight what is known in terms of OIT efficacy and effectiveness, safety, and impact on quality of life. For each aspect, we reported the pros and the cons, inferable from published literature. In conclusion, even though many protocols, reviews and meta-analysis have been published on this topic, pediatric OIT remains a controversial therapy and no definitive generalized conclusion may be drawn so far. It should be an option provided by specialized teams, when both patients and their families are prone to adhere to the proposed protocol. Efficacy, long-term effectiveness, possible role of adjuvant therapies, risk of severe reactions including anaphylaxis or eosinophilic esophagitis, and impact on the quality of life of both children and caregivers are all aspects that should be discussed before starting OIT. Future studies are needed to provide firm clinical and scientific evidence, which should also consider patient reported outcomes.

Management of Eosinophilic Esophagitis During Oral Immunotherapy

Food allergies are antigen-driven diseases that can lead to IgE-mediated reactions of immediate hypersensitivity (eg, anaphylaxis triggered by a single food) or non-IgE reactions of delayed hypersensitivity such as eosinophilic esophagitis (eg, inability to eat multiple foods manifesting as abdominal pain, choking, dysphagia, vomiting, reflux, food impaction). Although both types of disease have their own unique set of challenges in diagnosis and management, it is a particularly vexing problem when a patient is afflicted by both conditions. This situation can happen when individuals with IgE-mediated food allergy undergo desensitization using currently available forms of oral immunotherapy. In this Grand Rounds Review, we review diagnostic approaches to oral immunotherapy-associated eosinophilic esophagitis, potential relationships between primary and secondary eosinophilic esophagitis, potential management approaches, areas of uncertainty, and upcoming research. Optimally supporting patients in their journey with food allergy requires shared decision making regarding alternative management strategies and the stimulation of robust research.

Eosinophilic gastrointestinal disorders and allergen immunotherapy: Lights and shadows

Allergic diseases, such as IgE-mediated food allergy, asthma, and allergic rhinitis, are relevant health problems worldwide and show an increasing prevalence. Therapies for food allergies are food avoidance and the prompt administration of intramuscular epinephrine in anaphylaxis occurring after accidental exposure. However, allergen immunotherapy (AIT) is being investigated as a new potential tool for treating severe food allergies. Effective oral immunotherapy (OIT) and epicutaneous immunotherapy (EPIT) induce desensitization and restore immune tolerance to the causal allergen. While immediate side effects are well known, the long-term effects of food AIT are still underestimated. In this regard, eosinophilic gastrointestinal disorders (EGIDs), mainly eosinophilic esophagitis, have been reported as putative complications of OIT for food allergy and sublingual immunotherapy (SLIT) for allergic asthma and rhinitis. Fortunately, these complications are usually reversible and the patient recovers after AIT discontinuation. This review summarizes current knowledge on the possible causative link between eosinophilic gastrointestinal disorders and AIT, highlighting recent evidence and controversies.

The role of eosinophils in immunotherapy

PURPOSE OF REVIEW

The purpose of this review is to provide a brief discussion on the differential diagnosis for peripheral eosinophilia. We will then focus on targeted immunotherapies for atopic disease, their effects on absolute peripheral eosinophil counts, and use of peripheral eosinophils as a predictor of treatment response.

RECENT FINDINGS

In atopic disease, lower absolute peripheral eosinophil counts are typically associated with improved outcomes. Much of the current evidence on eosinophils as a biomarker comes from post-hoc analyses in therapeutic immunotherapy. While changes in eosinophilia were not the primary outcome of interest in many studies, some patterns did emerge. Cytolytic mAbs AK002 and benralizumab completely reduce peripheral and tissue eosinophil numbers. Dupilumab may have paradoxical transient eosinophilia despite observed clinical efficacy.

SUMMARY

Atopic inflammation is complex largely due to the various cytokines which affect eosinophils activation, proliferation, differentiation, and survival. This demonstrates the challenges of using peripheral eosinophilia alone as a biomarker for atopic disease activity. More attention should spotlight how different immunotherapy modalities affect eosinophil-driven responses.

Gastrointestinal Eosinophil Responses in a Longitudinal, Randomized Trial of Peanut Oral Immunotherapy

BACKGROUND & AIMS

Gastrointestinal side effects are common during oral immunotherapy (OIT) and eosinophilic esophagitis (EoE) is a potential complication. We aimed to characterize eosinophilic gastrointestinal responses to peanut OIT, in which peanut protein is given orally, with incremental increases in dose over time.

METHODS

Twenty adults with IgE-mediated peanut allergy were randomly assigned to groups given peanut OIT (n = 15) or placebo (n = 5); 1 additional subject withdrew before randomization. Serial gastrointestinal biopsies were collected at baseline (n = 21, 0 weeks), following dose escalation (n = 10, 52 weeks), and during the maintenance phase (n = 11, 104 weeks). Endoscopic findings were characterized using the EoE endoscopic reference score. Biopsies were assessed for eosinophils per high-power field (eos/hpf) and other pathology features using EoE histologic scoring system scores. We performed immunohistochemical analyses of eosinophil peroxidase deposition, quantified using automated image analysis.

RESULTS

At baseline, no subjects reported current gastrointestinal symptoms. However, 3 of the 21 subjects (14%) had esophageal peak eosinophil counts ≥15 eos/hpf and all subjects had dilated intercellular spaces (DIS). OIT induced or exacerbated esophageal eosinophilia (EE) at 52 weeks in most subjects (peak eosinophil counts >5 eos/hpf in 6 of 7 patients [86%]; peak eosinophil counts ≥15 eos/hpf in 4 of 7 patients [57%]). One subject met clinicopathologic criteria for EoE and withdrew; no significant changes in esophageal peak eosinophil counts were observed in the placebo group. EE in the OIT group corresponded with significant increases in EoE histologic scoring system scores and deposition of eosinophil peroxidase. In 4 of 6 participants (67%), OIT-induced EE and gastrointestinal eosinophilia resolved by the end of the maintenance phase. Gastrointestinal symptoms were not clearly associated with EE or gastrointestinal eosinophilia.

CONCLUSIONS

In this pilot study, we found that peanut OIT-induced EE and gastrointestinal eosinophilia are usually transient and are not always associated with gastrointestinal symptoms. Clinicaltrials.gov no: NCT02103270.

Integrating oral immunotherapy into clinical practice

In 2020, the first food allergy treatment, an oral immunotherapy (OIT) product for peanut allergy, was approved by the Food and Drug Administration, and a peanut epicutaneous immunotherapy patch was under review. As food allergy therapies become available and widespread, allergy offices will need to adjust practices to be able to offer their patients these new treatments. OIT is an intensive therapy that requires commitment from patients and their families, and open communication with the practice is paramount. OIT may not be the right therapy for every patient, and although identifying good candidates is still an area rich for research opportunity, experience from cohorts and clinical trials provides some insight. It is important to understand the scope of practice for each member of the OIT team based on state regulations for a particular location. Staffing and space will likely dictate how many patients at an individual office could be on active OIT at one time. Emergency medications, supplies, and protocols must be in place. Screening, scheduling, visit procedures, monitoring, home dosing, dose modifications, safety precautions, adverse reactions, and maintenance will be addressed in this article. Finally, adjunct therapies under investigation will be reviewed.

Eosinophils in Eosinophilic Esophagitis: The Road to Fibrostenosis is Paved With Good Intentions

Eosinophilic esophagitis (EoE) is an antigen-driven disease associated with epithelial barrier dysfunction and chronic type 2 inflammation. Eosinophils are the defining feature of EoE histopathology but relatively little is known about their role in disease onset and progression. Classically defined as destructive, end-stage effector cells, eosinophils (a resident leukocyte in most of the GI tract) are increasingly understood to play roles in local immunity, tissue homeostasis, remodeling, and repair. Indeed, asymptomatic esophageal eosinophilia is observed in IgE-mediated food allergy. Interestingly, EoE is a potential complication of oral immunotherapy (OIT) for food allergy. However, we recently found that patients with peanut allergy may have asymptomatic esophageal eosinophilia at baseline and that peanut OIT induces transient esophageal eosinophilia in most subjects. This is seemingly at odds with multiple studies which have shown that EoE disease severity correlates with tissue eosinophilia. Herein, we review the potential role of eosinophils in EoE at different stages of disease pathogenesis. Based on current literature we suggest the following: (1) eosinophils are recruited to the esophagus as a homeostatic response to epithelial barrier disruption; (2) eosinophils mediate barrier-protective activities including local antibody production, mucus production and epithelial turnover; and (3) when type 2 inflammation persists, eosinophils promote fibrosis.

Eosinophilic Esophagitis as a Side Effect of Food Oral Immunotherapy

Food allergies (FAs) include a spectrum of immune-mediated serious and potentially life-threatening medical conditions with an overall estimated prevalence ranging from 4% to 8% in the U.S. and Europe. Significant progress in food allergen-specific immunotherapy has been accomplished over the past 10 years. The most studied strategy has been oral immunotherapy (OIT), also known as food desensitization, a treatment in which a child is slowly and deliberately given a small amount of the food to ingest (that previously was a food allergy trigger) with the ultimate goal of the child eating that food without a reaction. OIT is now recommended in the European guidelines for the treatment of milk, egg, and peanut allergies and was the first American Food Drug Administration (FDA) approved product for the prevention of severe reaction to peanuts in 4–17 year olds to be released on the market. The side effects associated with OIT treatment trials are mild to moderate, predominantly oropharyngeal, and easily treated. More severe reactions, such as generalized urticaria/angioedema, wheezing/respiratory distress, laryngeal edema, and repetitive emesis, have been reported. However systemic reactions are very rare. Low-dose immunotherapy is associated with significantly fewer side effects. Currently, its most limiting allergic side effect is that approximately 10–15% of subjects treated with OIT experience gastrointestinal symptoms, preventing the continuation of therapy. Eosinophilic esophagitis (EoE) has also been reported as a cause of persistent abdominal symptoms in OIT.

How to approach adult patients with asymptomatic esophageal eosinophilia

As the awareness among gastroenterologists regarding endoscopic features suggesting eosinophilic esophagitis is increasing, individuals without symptoms of esophageal dysfunction are increasingly being found to have esophageal eosinophilia on biopsies performed during upper gastrointestinal endoscopies. However, the course of disease and the management of these asymptomatic individuals with esophageal eosinophilia remain elusive. In this review, we propose a definition of asymptomatic individuals with esophageal eosinophilia and discuss the prevalence, risk factors, and course of disease of this specific patient group. Furthermore, we have established a diagnostic and therapeutic pathway based on the most recent available data.

Food allergy and eosinophilic gastrointestinal disorders

Eosinophilic esophagitis (EoE) is a non-immunoglobulin E mediated disorder that has been seen with increasing frequency over the past 25 years. Although the presentation varies per age group from vomiting and refusal to eat in infants and toddlers to abdominal pain and dysphagia in school-aged children, and food impaction and indigestion in adolescents and adults. Treatment options include proton-pump inhibitors, dietary avoidance, swallowed steroids, or a combination of these. Newer therapies with biologics show promise in early studies. Cow's milk is the most common food trigger of EoE across all age groups, followed by wheat and eggs. Different dietary avoidance strategies have been used, and help from a knowledgeable nutritionist is often key to success. Patients with EoE commonly have other baseline atopic disease. Clinicians who take care of patients who are atopic, therefore, should have a higher index of suspicion for EoE in patients with dysphagia. The goals of treatment are both a decrease in symptoms and normalization of esophageal histology. Eosinophilic gastrointestinal diseases are less common and less likely to respond to dietary therapies and/or avoidance. Pathogenesis seems to be different and may be more autoimmune mediated. Trialing dietary restrictions is certainly an option in this cohort of patients. For persistent symptoms and abnormalities, systemic medications have been used, although biologics may be used in the future. Additional studies are needed to determine which patients will respond to which therapies.

Eosinophilic esophagitis during sublingual and oral allergen immunotherapy

PURPOSE OF REVIEW

The aim of this review is to discuss the current evidence regarding the development of eosinophilic esophagitis (EoE) in individuals undergoing oral and sublingual immunotherapy (SLIT) for both food and environmental allergens. Cumulative incidence of EoE in patients on allergen immunotherapy for peanut, milk, and egg is estimated.

RECENT FINDINGS

De novo development of EoE in patients undergoing oral and SLIT has been demonstrated on the scale of case reports and prospective randomized trials. However, few individuals with EoE-like symptoms during immunotherapy undergo endoscopy, and the long-term outcomes of immunotherapy-associated EoE are unknown.

SUMMARY

Evidence exists to suggest that allergen immunotherapy could place individuals at risk for the development of EoE, the true incidence of which may vary depending on antigen exposure and methods used to define the condition.

Summary of the Keystone Symposium "Origins of allergic disease: Microbial, epithelial and immune interactions," March 24-27, Tahoe City, California

The aims of the Keystone Symposium conference, "Origins of allergic disease: Microbial, epithelial and immune interactions" were to present and discuss potential microbial-epithelial-immune interactions underlying the early-life origins of allergic disorders, as well as immune mechanisms that might suggest novel disease prevention or intervention strategies. Cross-talk and sharing of ideas among participating experts in basic science and clinical aspects of allergic diseases provided substantial insight into the concept of allergic disorders as a systems disease. The overriding message distilled from the discussions was that damage to epithelial surfaces lies at the origin of the various manifestations of allergic disease. The epithelium of the lungs, gut, and skin, which operates as a critical sensor of environmental stimuli, is besieged by an onslaught of contemporary environmental forces including an altered microbiome, air pollution, food allergens in a changed diet, and chemicals in modern detergents. Collectively, this onslaught leads to alterations of lung, skin, or gut epithelial surfaces, driving a type 2 immune response that underlies most, if not all, of the atopic diseases. Possible remedies for treatment and prevention of allergic diseases were discussed, including a precision medicine approach using biologics, oral desensitization, targeted gut microbiome alterations, and behavior alteration.

The Role of the Environment in Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic, immune-mediated inflammatory disease with incompletely understood pathogenesis. Though disease manifestations were initially ascribed to a delayed reaction to food allergens, emerging evidence suggests that modifiable host factors and environmental allergen exposure may also play critical roles in the pathogenesis and ongoing manifestations of EoE. As with other atopic diseases, lack of early-life exposure to microbial pathogens leads to an immune tolerance defect and reprograms the commensal gut microflora toward a type 2 T helper (Th2) phenotype; the esophageal microbiota, a rich environment consisting of diverse bacterial species, is greatly altered by inflammation. Although multiple early life microbiome-altering factors are associated with EoE development, no causative, direct relationships have been identified. Interestingly, large, cross-sectional analyses of several populations identify an inverse relationship between Helicobacter pylori presence and EoE, likely via virulence factors that downregulate Th2 inflammation, though causality has not been proven. In regard to environmental allergens, some studies support seasonal variation in EoE diagnosis and flares, and EoE can be generated after a large, identifiable aeroallergen exposure. Examples include mouse models of intranasal Aspergillus dosing and following initiation of oral immunotherapy to foods or environmental allergens. Conversely, treatment of allergic rhinoconjunctivitis may improve EoE symptoms, though data is limited to case reports and small series. Unfortunately, biologic therapies for atopic conditions have failed to improve EoE symptoms despite improvement in esophageal eosinophil count, though dupilumab shows promise in ongoing studies. Overall, this chapter shows that EoE pathogenesis is likely multifactorial, and the environment is a key component in our understanding of EoE.

The Role of the Environment in Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic, immune-mediated inflammatory disease with incompletely understood pathogenesis. Though disease manifestations were initially ascribed to a delayed reaction to food allergens, emerging evidence suggests that modifiable host factors and environmental allergen exposure may also play critical roles in the pathogenesis and ongoing manifestations of EoE. As with other atopic diseases, lack of early-life exposure to microbial pathogens leads to an immune tolerance defect and reprograms the commensal gut microflora toward a type 2 T helper (Th2) phenotype; the esophageal microbiota, a rich environment consisting of diverse bacterial species, is greatly altered by inflammation. Although multiple early life microbiome-altering factors are associated with EoE development, no causative, direct relationships have been identified. Interestingly, large, cross-sectional analyses of several populations identify an inverse relationship between Helicobacter pylori presence and EoE, likely via virulence factors that downregulate Th2 inflammation, though causality has not been proven. In regard to environmental allergens, some studies support seasonal variation in EoE diagnosis and flares, and EoE can be generated after a large, identifiable aeroallergen exposure. Examples include mouse models of intranasal Aspergillus dosing and following initiation of oral immunotherapy to foods or environmental allergens. Conversely, treatment of allergic rhinoconjunctivitis may improve EoE symptoms, though data is limited to case reports and small series. Unfortunately, biologic therapies for atopic conditions have failed to improve EoE symptoms despite improvement in esophageal eosinophil count, though dupilumab shows promise in ongoing studies. Overall, this chapter shows that EoE pathogenesis is likely multifactorial, and the environment is a key component in our understanding of EoE.