Eosinophilic disorders

Physiological Response, Haematology and Stress Condition of Scavenging Chickens in Cement Production Areas

This study investigated the physiological and stress indices of scavenging chickens in LAFARGE and Dangote cement factories located at Ewekoro and Ibese, respectively and respective adjourning communities of Ogun State, Nigeria. One hundred adult scavenging chickens comprising of 25 from each location were used. The birds were caught at night on their perch and kept in furnished cages till the next morning. Data were collected on their rectal temperature, pulse rate, and respiratory rate . Also 5 mL blood was collected through the wing vein of each chicken. Highest (p < 0.05) pulse rate (215.64 beat/minute) and respiratory rate (19.90 breath/minute) were recorded among the chickens at LAFARGE area. Highest (p < 0.05) packed cell volume (28.06%), hemoglobin (4.01 g/dL), monocyte (4.28%) and glucose (256.53 g/dL) were recorded among ones at Ibese (Dangote). White blood cell (6488.89 × 103µL) was highest (p < 0.05) in chickens at Ewekoro (LAFARGE). The study concluded that cement factories infringe on health status of scavenging chickens in the domains. Effective environmental mitigation programme should be put in place for enhanced welfare of the birds.

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

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

Proposed refined diagnostic criteria and classification of eosinophil disorders and related syndromes

Eosinophilia and eosinophil activation are recurrent features in various reactive states and certain hematologic malignancies. In patients with hypereosinophilia (HE), HE-induced organ damage is often encountered and may lead to the diagnosis of a hypereosinophilic syndrome (HES). A number of known mechanisms and etiologies contribute to the development of HE and HES. Based on these etiologies and the origin of eosinophils, HE and HES are divided into primary forms where eosinophils are clonal cells, reactive forms where an underlying reactive or neoplastic condition is detected and eosinophils are considered to be "non-clonal" cells, and idiopathic HE and HES in which neither a clonal nor a reactive underlying pathology is detected. Since 2012, this classification and the related criteria have been widely accepted and regarded as standard. However, during the past few years, new developments in the field and an increasing number of markers and targets have created a need to update these criteria and the classification of HE and HES. To address this challenge, a Working Conference on eosinophil disorders was organized in 2021. In this conference, a panel of experts representing the relevant fields, including allergy, dermatology, hematology, immunology, laboratory medicine, and pathology, met and discussed new markers and concepts as well as refinements in definitions, criteria and classifications of HE and HES. The outcomes of this conference are presented in this article and should assist in the diagnosis and management of patients with HE and HES in daily practice and in the preparation and conduct of clinical trials.

Controversies in Allergy: The Potential Role of Biologics as First-Line Therapy in Eosinophilic Disorders

With advances in understanding the role of eosinophils in disease pathogenesis, particularly in the airways, gastrointestinal tract, and skin, targeting eosinophils or the cytokines that lead to their production, activation, and survival has become an increasingly pursued therapeutic approach. Newly developed biologic agents target eosinophils directly, other cells interacting with or activating eosinophils, or cytokines in the type 2 inflammatory pathway with specific antibodies. Current treatment paradigms reserve therapy with biologics for patients refractory to or intolerant of corticosteroids or immunosuppressants. Given accumulating data for safety and efficacy of these biologics, however, there is the question of whether targeted treatments should be used earlier in the treatment algorithm. In this article, we discuss the pros and cons of using biologics as first-line therapy for eosinophilic diseases of the airways, gastrointestinal tract, and skin. We highlight emerging biologic agents and future directions for research, as well as a rationale for the early use of some biologics to prevent tissue damage, disease progression, and organ dysfunction in selected conditions.

Characteristics of Dermatological Patients With Blood Eosinophilia: A Retrospective Analysis of 453 Patients

BACKGROUND

Skin diseases associated with blood or tissue eosinophilia are common. Because these have various clinical manifestations, making the correct diagnosis can be challenging. So far, dermatological patients with concomitant blood eosinophilia have not been characterized.

OBJECTIVE

To investigate patterns of dermatological patients with concomitant blood eosinophilia to obtain information helpful for optimizing disease management.

METHODS

In this retrospective study, demographic and clinical data and diagnostic test results of all patients presenting with dermatoses associated with blood eosinophilia referred to a university center from 2014 to 2018 were extracted from the electronic patient charts and evaluated using descriptive and semantic map analyses.

RESULTS

A total of 453 patients (51.4% females; mean age, 58.4 ± 21.7 years) were included and grouped according to blood absolute eosinophil counts: severe, greater than or equal to 1.5 G/L (n = 87; 19.2%); moderate, 1.0 to 1.49 G/L (n = 73; 16.1%); and mild eosinophilia, 0.5 to 0.99 G/L (n = 293; 64.7%). Most patients presented with chronic (64.6%), generalized skin lesions (75.9%), and pruritus (88.1%). Statistical analyses revealed 3 distinct patterns: (1) mild eosinophilia associated with localized skin disease, age less than 50 years, history of atopy, and diagnosis of eczema or infectious disease; (2) moderate eosinophilia linked to generalized skin lesions, pruritus, age more than 70 years, and autoimmune bullous disease; and (3) severe eosinophilia associated with diagnosis of hypereosinophilic syndromes, drug hypersensitivity, or malignant disease.

CONCLUSIONS

Based on the pattern analysis of patients with dermatoses associated with blood eosinophilia, a diagnostic workup has been developed aiming at setting the correct differential diagnosis in a feasible and effective manner.

Hypereosinophilic syndrome presenting as eosinophilic gastroenteritis disorder and splinter hemorrhages: A case report

BACKGROUND

Eosinophilia and related organ damage are extensively studied hot topics among rare disorders. Any addition to the cohort of available case reports of the same will be adding knowledge for better management of this less known entity.

CASE SUMMARY

In this article, we describe a 27-year-old Indo-Aryan man who presented with abdominal pain, abdominal distension, and loose stools for variable days. He had splinter hemorrhages in the majority of fingernails. He was diagnosed with predominant eosinophilic gastrointestinal involvement with bowel obstruction and ascites, and was managed with intravenous immunoglobulin. He was subsequently treated with oral low dose steroid therapy and responded completely.

CONCLUSION

Our experience is evidence that prompt management of this hypereosinophilic lethal gastrointestinal (all three layers) infiltrative disease provides a cure and avoids complications. Splinter nail hemorrhages may be seen in the same disease.

History of Allergy: Clinical Descriptions, Pathophysiology, and Treatment

Allergy has shown a dramatic increase in prevalence in the last decades. However, allergic diseases are probably not new. Asthma and eczema have been described in ancient societies like Egypt, China and in the Greco-Roman culture. In the middle-ages descriptions of hay fever can be found in Persian-Arabian literature (called "rose fever"). Scientific allergology started in the nineteenth century with descriptions of hay fever and experimental studies showing pollen as elicitors. Milestones in the twentieth century comprise the description of anaphylaxis, the creation of the terms "allergy" and "atopy", the Prausnitz-Küstner test and finally the discovery of IgE and the development of the Radio-Allergo-Sorbent-Test (RAST) for routine detection of specific IgE antibodies. Progress in cellular immunology led to the description of T-cell subsets Th1 and Th2. Mast cell and basophil research progressed since the first description to histamine release studies. Leukotrienes were detected. Pharmacotherapy started in the early twentieth century with adrenaline (epinephrine) followed by antihistamines and cortisone. Allergen-specific immunotherapy was introduced. Epidemiologic studies pointed to a role of environmental pollutants as allergy enhancing factors and protective influences from farm environment. Through the progress in experimental allergology and immunology targeted therapeutics have been developed for various atopic conditions.

Eosinophils in skin diseases

Eosinophil infiltration is a common finding in a broad spectrum of skin diseases, despite the fact that the skin is devoid of eosinophils under physiologic conditions. Although cutaneous eosinophilia is reactive, cytokine-mediated in most cases, diseases with an intrinsic mutation-mediated clonal expansion of eosinophils can also manifest on the skin. As eosinophils are involved in host defense, regulate immune responses, generate pruritus, induce remodeling and fibrosis, and can cause tissue damage, they have the capacity to actively contribute to the pathogenesis of diseases. Recent research provided deeper insights in the mechanisms, e.g., bacterial and viral clearance, blister formation, recruitment of cytotoxic T cells, and generation of pruritus, by which eosinophils might come into action. This review aims at providing an overview on the clinical presentations of eosinophil-associated dermatoses and the current understanding of their pathogenic role in these diseases. Further, we discuss the effects of therapies targeting eosinophils.

Eosinophils and eosinophil-associated disorders: immunological, clinical, and molecular complexity

Eosinophils and their mediators play a crucial role in various reactive states such as bacterial and viral infections, chronic inflammatory disorders, and certain hematologic malignancies. Depending on the underlying pathology, molecular defect(s), and the cytokine- and mediator-cascades involved, peripheral blood and tissue hypereosinophilia (HE) may develop and may lead to organ dysfunction or even organ damage which usually leads to the diagnosis of a HE syndrome (HES). In some of these patients, the etiology and impact of HE remain unclear. These patients are diagnosed with idiopathic HE. In other patients, HES is diagnosed but the etiology remains unknown — these patients are classified as idiopathic HES. For patients with HES, early therapeutic application of agents reducing eosinophil counts is usually effective in avoiding irreversible organ damage. Therefore, it is important to systematically explore various diagnostic markers and to correctly identify the disease elicitors and etiology. Depending on the presence and type of underlying disease, HES are classified into primary (clonal) HES, reactive HES, and idiopathic HES. In most of these patients, effective therapies can be administered. The current article provides an overview of the pathogenesis of eosinophil-associated disorders, with special emphasis on the molecular, immunological, and clinical complexity of HE and HES. In addition, diagnostic criteria and the classification of eosinophil disorders are reviewed in light of new developments in the field.

Regulation of eosinophil functions by autophagy

Eosinophils are granule-containing leukocytes which develop in the bone marrow. For many years, eosinophils have been recognized as cytotoxic effector cells, but recent studies suggest that they perform additional immunomodulatory and homeostatic functions. Autophagy is a conserved intracellular process which preserves cellular homeostasis. Autophagy defects have been linked to the pathogenesis of many human disorders. Evidence for abnormal regulation of autophagy, including decreased or increased expression of autophagy-related (ATG) proteins, has been reported in several eosinophilic inflammatory disorders, such as Crohn's disease, bronchial asthma, eosinophilic esophagitis, and chronic rhinosinusitis. Despite the increasing extent of research using preclinical models of immune cell-specific autophagy deficiency, the physiological relevance of autophagic pathway in eosinophils has remained unknown until recently. Owing to the increasing evidence that eosinophils play a role in keeping organismal homeostasis, the regulation of eosinophil functions is of considerable interest. Here, we discuss the most recent advances on the role of autophagy in eosinophils, placing particular emphasis on insights obtained in mouse models of infections and malignant diseases in which autophagy has genetically dismantled in the eosinophil lineage. These studies pointed to the possibility that autophagy-deficient eosinophils exaggerate inflammation. Therefore, the pharmacological modulation of the autophagic pathway in these cells could be used for therapeutic interventions.

Physiology and pathology of eosinophils: Recent developments: Summary of the Focus Workshop Organized by DGAKI

Over the last century, eosinophils have been regarded ambiguously either as 'friends' or 'foes'. Recent developments have greatly enhanced our understanding of the role and function of eosinophils in health and disease. Pathogenic eosinophilic inflammation can lead to severe diseases in various organs, such as the gastrointestinal tract, airways, heart and skin. In a 2-day focus workshop of the German Society for Allergology and Clinical Immunology (DGAKI), the state of the art was discussed and practical recommendations for diagnosis and treatment of eosinophilic diseases, with a particular focus on new biologics, such as anti-interleukin 5 and anti-interleukin 5R, were derived.

ATG5 promotes eosinopoiesis but inhibits eosinophil effector functions

Eosinophils are white blood cells that contribute to the regulation of immunity and are involved in the pathogenesis of numerous inflammatory diseases. In contrast to other cells of the immune system, no information is available regarding the role of autophagy in eosinophil differentiation and functions. To study the autophagic pathway in eosinophils, we generated conditional knockout mice in which Atg5 is deleted within the eosinophil lineage only (designated Atg5eoΔ mice). Eosinophilia was provoked by crossbreeding Atg5eoΔ mice with Il5 (IL-5) overexpressing transgenic mice (designated Atg5eoΔIl5tg mice). Deletion of Atg5 in eosinophils resulted in a dramatic reduction in the number of mature eosinophils in blood and an increase of immature eosinophils in the bone marrow. Atg5-knockout eosinophil precursors exhibited reduced proliferation under both in vitro and in vivo conditions but no increased cell death. Moreover, reduced differentiation of eosinophils in the absence of Atg5 was also observed in mouse and human models of chronic eosinophilic leukemia. Atg5-knockout blood eosinophils exhibited augmented levels of degranulation and bacterial killing in vitro. Moreover, in an experimental in vivo model, we observed that Atg5eoΔ mice achieve better clearance of the local and systemic bacterial infection with Citrobacter rodentium. Evidence for increased degranulation of ATG5low-expressing human eosinophils was also obtained in both tissues and blood. Taken together, mouse and human eosinophil hematopoiesis and effector functions are regulated by ATG5, which controls the amplitude of overall antibacterial eosinophil immune responses.

Diagnostic Value of Mid-esophageal Biopsies in Pediatric Patients With Eosinophilic Esophagitis

INTRODUCTION

Eosinophilic esophagitis (EoE) is histologically defined as the presence of 15 or more intraepithelial eosinophils per high-power fields. Limited consensus exists on where to sample the esophagus in pediatrics. This study aimed to identify whether endoscopic and histologic examination of the mid esophagus offers diagnostic value compared to proximal/distal esophageal biopsies.

METHODS

A retrospective chart review of pediatric patients with EoE was performed. Endoscopic and histologic parameters were assessed at the initial and follow-up visits, and concordance between proximal/distal biopsy and mid biopsy was determined.

RESULTS

A total of 100 patients with a mean age of 9.6 ± 4.07 years were included. Endoscopic parameters between proximal/distal and mid esophagus were concordant in 84% to 97% of patients (initial assessment) and in 80% to 97% of patients (at follow-up). Mid esophagus showed endoscopic abnormalities, which were absent at the proximal/distal esophagus in 1% to 5% of patients, as well as histologic abnormalities in 2% to 8% of patients overall at initial and follow-up examinations.

CONCLUSIONS

We recommend continued endoscopic and histologic assessment of the proximal/distal biopsy; however, examination of the mid esophagus does offer small diagnostic value in our subset of patients. Future studies need to be conducted before conclusive recommendations supporting the use of mid-esophageal biopsies can be made.

Successful Long-Term Control of the Syndrome of Episodic Angioedema With Eosinophilia (Gleich Syndrome) With Low-Dose Imatinib Mesylate and Prednisone

The syndrome of episodic angioedema with eosinophilia, first reported over 40 years ago, is a hypereosinophilic disorder that, uniquely, is not associated with end-organ pathology. However, patients develop a constellation of symptoms that include angioedema, urticaria, fatigue, and fever. Episodes are accompanied by massive hypereosinophilia and weight gain. Type II serum cytokine levels (IL-5, IL-13, IL-9, and IL-10) show cyclic variations peaking at or just prior to the peak of eosinophilia and an abnormal Th2 cell phenotype has been reported. Attacks may occur with predictable regularity and have been described in both adults and children. Glucocorticoid therapy reliably reverses symptoms with accompanying diuresis, defervesce, and normalization of the eosinophil count. In this report, a patient who had the syndrome of episodic angioedema with eosinophilia exceeding 20 years is reported. He has had no end-organ damage to date. Testing for the CHIC2 deletion, a surrogate for the FIP1L1-PDGFRA fusion, was negative. Use of imatinib mesylate, initially as a steroid-sparing agent, and subsequently as a maintenance medication, plus low-dose prednisone has provided long-term control of hypereosinophilia and all clinical manifestations.

Tumor-associated tissue eosinophilia versus tumor associated blood eosinophilia: A ratio of diagnostic importance in oral squamous cell carcinoma

Introduction

Eosinophils are multifunctional granulocytes, which play a pivotal role in health and disease. Tumor Associated Tissue Eosinophilia (TATE) has long been evaluated in the diagnosis and progression of oral squamous cell carcinomas (OSCCs). However, their association with Tumor Associated Blood Eosinophilia (TABE) in OSCCs is still far fetched. We, therefore, attempted to evaluate their individual roles and to achieve a ratio between TATE and TABE in order to signify its usage in objectifying the diagnosis.

Materials and Methods

TATE was evaluated using H and E stain per 10 high power fields in 33 previously diagnosed cases of OSCC which were retrieved from department archives. TABE values were achieved from complete blood hemogram reports of patients. TATE/TABE ratio was calculated. All the parameters were clinicopathologically correlated and statistically evaluated using SPSS.

Results

TATE represented higher values in well-differentiated squamous cell carcinoma (WDSCC) and poorly differentiated squamous cell carcinoma (PDSCC) and was least in moderately differentiated squamous cell carcinoma (MDSCC), whereas TABE linearly increased from WDSCC to PDSCC. TNM Stage II cases revealed the highest TATE and lowest TABE. TATE/TABE ratio was the highest in WDSCC.

Conclusion

Due to the dual nature of eosinophils in early and late carcinogenesis events, evaluation of only TATE might not be conclusive in determining tumor grade. Hence, in a first of its kind attempt, the TATE/TABE ratio may be suitable to achieve a criterion for the determination of tumor grade and may also help to unfold the underlying biologic events.

Apolipoprotein A-IV acts as an endogenous anti-inflammatory protein and is reduced in treatment-naïve allergic patients and allergen-challenged mice

Background

Recent studies pointed to a crucial role for apolipoproteins in the pathogenesis of inflammatory diseases. However, the role of apolipoprotein‐IV (ApoA‐IV) in allergic inflammation has not been addressed thoroughly thus far.

Objective

Here, we explored the anti‐inflammatory effects and underlying signaling pathways of ApoA‐IV on eosinophil effector function in vitro and in vivo.

Methods

Migratory responsiveness, Ca²⁺‐flux and apoptosis of human peripheral blood eosinophils were assessed in vitro. Allergen‐driven airway inflammation was assessed in a mouse model of acute house dust mite‐induced asthma. ApoA‐IV serum levels were determined by ELISA.

Results

Recombinant ApoA‐IV potently inhibited eosinophil responsiveness in vitro as measured by Ca²⁺‐flux, shape change, integrin (CD11b) expression, and chemotaxis. The underlying molecular mechanism involved the activation of Rev‐ErbA‐α and induced a PI3K/PDK1/PKA‐dependent signaling cascade. Systemic application of ApoA‐IV prevented airway hyperresponsiveness (AHR) and airway eosinophilia in mice following allergen challenge. ApoA‐IV levels were decreased in serum from allergic patients compared to healthy controls.

Conclusion

Our data suggest that ApoA‐IV is an endogenous anti‐inflammatory protein that potently suppresses effector cell functions in eosinophils. Thus, exogenously applied ApoA‐IV may represent a novel pharmacological approach for the treatment of allergic inflammation and other eosinophil‐driven disorders.

Relationship between tissue and serum eosinophilia in children undergoing adenotonsillectomy with allergic rhinitis

Background/aim

Previous reports suggested that allergic/eosinophilic inflammation affects the adenoid and tonsillar tissue. The aim of this study is to evaluate and compare the tissue and serum eosinophilia in children undergoing adenotonsillectomy with allergic rhinitis.

Materials and methods

The clinical registers of 125 children undergoing adenoidectomy/tonsillectomy due to adenoid/tonsil hypertrophy were examined and reviewed retrospectively. Fifty-seven children with positive skin prick test and symptoms of allergic rhinitis were included in the study as the atopic group, whereas 68 children with no allergic symptoms and negative skin prick test were included as the nonatopic group. Consequently, the total immunoglobulin E level and the serum and tissue eosinophilia of the atopic and nonatopic groups were compared.

Results

Serum eosinophilia in the atopic group was found to be significantly higher than in the nonatopic group (P = 0.045). A significantly higher eosinophil count was found in adenoid/tonsil tissue of the atopic group (P < 0.001, P = 0.023, respectively). However, no significant correlation between tissue and serum eosinophilia was found.

Conclusion

The inconsistency between tissue and serum eosinophilia in atopic children would particularly indicate a role of local atopy in adenotonsillar hypertrophy. Further studies are needed to better understand the effect and usefulness of serum and tissue eosinophilia in children with allergic rhinitis.

The Cellular Functions of Eosinophils: Collegium Internationale Allergologicum (CIA) Update 2020

Eosinophils and their secretory mediators play an important role in the pathogenesis of infectious and inflammatory disorders. Although eosinophils are largely evolutionally conserved, their physiologic functions are not well understood. Given the availability of new eosinophil-targeted depletion therapies, there has been a renewed interest in understanding eosinophil biology as these strategies may result in secondary disorders when applied over long periods of time. Recent data suggest that eosinophils are not only involved in immunological effector functions but also carry out tissue protective and immunoregulatory functions that actively contribute to the maintenance of homeostasis. Prolonged eosinophil depletion may therefore result in the development of secondary disorders. Here, we review recent literature pointing to important roles for eosinophils in promoting immune defense, antibody production, activation of adipose tissue, and tissue remodeling and fibrosis. We also reflect on patient data from clinical trials that feature anti-eosinophil therapeutics.

Adenosquamous carcinoma of the uterine cervix displaying tumor-associated tissue eosinophilia

Background:

Tumor-associated tissue eosinophilia is defined as an inflammatory response with the marked infiltration of eosinophils within tumor tissues. Tumor-associated tissue eosinophilia has been reported in various organs; however, no studies have examined the detailed cytopathological findings of tumor-associated tissue eosinophilia.

Case Presentation:

A 49-year-old woman presented with lower abdominal and back pain that had started 1 month earlier. A cervical biopsy revealed a diagnosis of non-keratinizing squamous cell carcinoma. A mildly increased number of eosinophils was observed in both cervical cytology and a biopsy. On pelvic computed tomography, a tumor mass measuring up to 5.5 cm in the largest diameter was seen in the uterine cervix. After 1 month, endometrial cytology was performed, and non-keratinizing squamous cell carcinoma together with normal endometrial glands was obtained in a background of marked eosinophil numbers. Tumor cells in an irregular-shaped solid nest had variable-sized hyperchromatic nuclei and light-green-stained cytoplasm. The number of eosinophils was obviously increased. Considering the possibility of tumor-associated tissue eosinophilia, we evaluated a peripheral blood sample and confirmed an increased number of eosinophils. Radical hysterectomy was performed, and the final pathological diagnosis was adenosquamous carcinoma. Although the number of eosinophils decreased after surgery, it increased again at the time of recurrence 1 year later. Chemo-irradiation was performed, but the patient died 1 year and 8 months after the operation.

Conclusion:

Cytopathologists should consider the presence of tumor-associated tissue eosinophilia by focusing on not only tumor cells but also the markedly eosinophilic background. The eosinophil count might be a useful marker of the disease activity.

Detection of α-defensin in eosinophils in helminth-infected mouse model

α-defensin is a potent antimicrobial peptide secreted from intestinal mucosal epithelial cells, such as Paneth cells, and affects not only bacteria but also parasites and fungi. Recently, human eosinophils have also been shown to produce α-defensin, but no studies have been done on other animals. In this study, we attempted to detect α-defensin protein in mouse eosinophils infiltrating the intestinal mucosa during a helminth infection using Zamboni fixation and immunohistochemistry. Most of the eosinophils infiltrating the intestinal mucosa during helminth infection were positive for α-defensin. The expression level of α-defensin mRNA was 50 fold that in the control. Meanwhile, the number of Paneth cells was doubled, and their α-defensin fluorescence intensity was increased. These results suggested that eosinophils are also important producers of α-defensin, such as Paneth cells in mice, and that α-defensin produced from eosinophils might be involved in defensive mechanisms against helminths. Moreover, the experimental system used in this study is a good model to study the generation of α-defensin by eosinophils.

mTOR complexes differentially orchestrates eosinophil development in allergy

Eosinophil infiltration is considered a hallmark in allergic airway inflammation, and the blockade of eosinophil differentiation may be an effective approach for treating eosinophil-related disorders. Mammalian target of rapamycin (mTOR) is a vital modulator in cell growth control and related diseases, and we have recently demonstrated that rapamycin can suppress eosinophil differentiation in allergic airway inflammation. Considering its critical role in haematopoiesis, we further investigated the role of mTOR in eosinophil differentiation in the context of asthmatic pathogenesis. Intriguingly, the inhibition of mTOR, either by genetic deletion or by another pharmacological inhibitor torin-1, accelerated the eosinophil development in the presence of IL-5. However, this was not observed to have any considerable effect on eosinophil apoptosis. The effect of mTOR in eosinophil differentiation was mediated by Erk signalling. Moreover, myeloid specific knockout of mTOR or Rheb further augmented allergic airway inflammation in mice after allergen exposure. Ablation of mTOR in myeloid cells also resulted in an increased number of eosinophil lineage-committed progenitors (Eops) in allergic mice. Collectively, our data uncovered the differential effects of mTOR in the regulation of eosinophil development, likely due to the distinct functions of mTOR complex 1 or 2, which thus exerts a pivotal implication in eosinophil-associated diseases.

Eosinophils as putative therapeutic targets in bullous pemphigoid

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering skin disease and is characterized by the presence of autoantibodies directed against the hemidesmosomal proteins BP180 and BP230 that can be detected in the skin and serum of BP patients. Histologically, the dermal infiltration of eosinophils is obvious. The objective of this review was to present evidence that eosinophils play a key role in the pathogenesis of BP. Eosinophils, together with cytokines and chemokines regulating their production, recruitment and activation, are abundantly present in lesional skin, in blisters and in peripheral blood of patients with BP. Recently, using a cryosection model, eosinophils were demonstrated to induce dermal-epidermal separation in the presence of BP antibodies. Thus, eosinophils and their products, as well as mediators regulating their function, present promising targets for the treatment of BP.

How I Diagnose Hypereosinophilic Syndromes

Hypereosinophilic syndromes are a group of disorders characterised by significant eosinophilia and organ damage. They have proven challenging to define, diagnose, and study for many years, due in part to their variable clinical presentations, the overlap between neoplastic and reactive eosinophilia, and the lack of a universal marker of eosinophil clonality. Herein, we give an overview of the term and discuss aetiology and our approach to diagnosis.

Eosinophilia secondary to lenalidomide therapy

WHAT IS KNOWN AND OBJECTIVE

Limited data are available on eosinophilia as a drug adverse event. We describe a case of eosinophilia from lenalidomide therapy.

CASE DESCRIPTION

A 50-year-old woman received lenalidomide, dexamethasone and cyclophosphamide as POEMS syndrome treatment. Eosinophil count rose during lenalidomide treatment and decreased in the periods off treatment. Naranjo nomogram suggested a probable association between the use of lenalidomide and eosinophilia.

WHAT IS NEW AND CONCLUSION

Eosinophilia has rarely been described with lenalidomide. This case shows a clear temporal relationship between lenalidomide and eosinophilia.

Evidence for a role of eosinophils in blister formation in bullous pemphigoid

BACKGROUND

Bullous pemphigoid (BP) is an autoimmune bullous disease of the skin characterized by subepidermal blister formation due to tissue-bound and circulating autoantibodies to the hemidesmosomal antigens BP180 and BP230. Although eosinophils and their toxic mediators are found abundantly in BP lesions, their role in blister formation has remained unclear.

OBJECTIVE

To investigate the role of eosinophils in the pathogenesis of BP with a specific focus on blister formation and to define conditions inducing dermal-epidermal separation (DES).

METHODS

In an ex vivo human model of BP, normal human skin cryosections were incubated with purified human peripheral blood eosinophils with or without activation in the presence or absence of BP autoantibodies, brefeldin A, diphenyleneiodonium, DNase or blocking F(ab')₂ fragments to CD16, CD18, CD32 and CD64. Dermal-epidermal separation was assessed by light microscopy studies and quantified using Fiji software.

RESULTS

Following activation with IL-5 and in the presence of BP autoantibodies, eosinophils induced separation along the dermal-epidermal junction of ex vivo skin. Dermal-epidermal separation was significantly reduced by blocking any of the following: Fcγ receptor binding (P = 0.048), eosinophil adhesion (P = 0.046), reactive oxygen species (ROS) production (P = 0.002), degranulation (P < 0.0001) or eosinophil extracellular trap (EET) formation (P = 0.048).

CONCLUSIONS

Our results provide evidence that IL-5-activated eosinophils directly contribute to BP blister formation in the presence of BP autoantibodies. Dermal-epidermal separation by IL-5-activated eosinophils depends on adhesion and Fcγ receptor activation, requires elevated ROS production and degranulation and involves EET formation. Thus, targeting eosinophils may be a promising therapeutic approach for BP.

Regulatory Eosinophils Suppress T Cells Partly through Galectin-10

Eosinophils have the capacity to regulate the function of T cell subsets. Our aim was to test the hypothesis of the existence of a regulatory subset of eosinophils. Human eosinophils were incubated with T cells that were stimulated with allogeneic leukocytes or CD3/CD28 cross-linking. After 2 d of coculture, 11% of the eosinophils gained CD16 expression. A CD16^hi subset of eosinophils, encompassing 1-5% of all eosinophils, was also identified in the blood of healthy subjects. FACS sorting showed that these CD16^hi eosinophils were significantly stronger suppressors of T cell proliferation than were conventional CD16^neg eosinophils. Human eosinophils contain stores of the immunoregulatory protein galectin-10. We found that Ab-mediated neutralization of galectin-10 partially abrogated the suppressive function of the eosinophils. Moreover, recombinant galectin-10 by itself was able to suppress T cell proliferation. Finally, we detected galectin-10-containing immune synapses between eosinophils and lymphocytes. To conclude, we describe a subset of suppressive eosinophils expressing CD16 that may escape detection because CD16-based negative selection is the standard procedure for the isolation of human eosinophils. Moreover, we show that galectin-10 functions as a T cell-suppressive molecule in eosinophils.

Adhesion-induced eosinophil cytolysis requires the receptor-interacting protein kinase 3 (RIPK3)-mixed lineage kinase-like (MLKL) signaling pathway, which is counterregulated by autophagy

BACKGROUND

Eosinophils are a subset of granulocytes that can be involved in the pathogenesis of different diseases, including allergy. Their effector functions are closely linked to their cytotoxic granule proteins. Release takes place through several different mechanisms, one of which is cytolysis, which is associated with release of intact granules, so-called clusters of free eosinophil granules. The mechanism underlying this activation-induced form of cell death in eosinophils has remained unclear.

OBJECTIVE

We aimed to elucidate the molecular mechanism of eosinophil cytolysis.

METHODS

Isolated blood eosinophils were incubated on glass coverslips coated with intravenous immunoglobulin and inactive complement component 3b. A morphologic characterization of the distinct stages of the proposed cascade was addressed by means of time-lapse automated fluorescence microscopy, electron microscopy, and immunohistochemistry. Experiments with pharmacologic inhibitors were performed to elucidate the sequence of events within the cascade. Tissue samples of patients with eosinophilic skin diseases or eosinophilic esophagitis were used for in vivo analyses.

RESULTS

After eosinophil adhesion, we observed reactive oxygen species production, early degranulation, and granule fusion processes, leading to a distinct morphology exhibiting cytoplasmic vacuolization and, finally, cytolysis. Using a pharmacologic approach, we demonstrate the presence of a receptor-interacting protein kinase 3 (RIPK3)-mixed lineage kinase-like (MLKL) signaling pathway in eosinophils, which, after its activation, leads to the production of high levels of reactive oxygen species in a p38 mitogen-activated protein kinase and phosphatidylinositol 3'-kinase-dependent manner. All these steps are required for cytoplasmic vacuolization and subsequent cytolysis to occur. Interestingly, triggering cytolysis is associated with an induction of autophagy in eosinophils, and additional stimulation of autophagy by means of pharmacologic inhibition of the mechanistic target of rapamycin counterregulates cell death. Moreover, MLKL phosphorylation, cytoplasmic vacuolization, and cytolysis were observed in eosinophils under in vivo inflammatory conditions.

CONCLUSION

We report that adhesion-induced eosinophil cytolysis takes place through RIPK3-MLKL-dependent necroptosis, which can be counterregulated by autophagy.

An epigenome-wide association study of total serum IgE in Hispanic children

BACKGROUND

Total IgE is a therapeutic target in patients with allergic diseases. DNA methylation in white blood cells (WBCs) was associated with total IgE levels in an epigenome-wide association study of white subjects. Whether DNA methylation of eosinophils explains these findings is insufficiently understood.

METHODS

We tested for association between genome-wide DNA methylation in WBCs and total IgE levels in 2 studies of Hispanic children: the Puerto Rico Genetics of Asthma and Lifestyle Study (PR-GOAL; n = 306) and the Genes-environments and Admixture in Latino Americans (GALA II) study (n = 573). Whole-genome methylation of DNA from WBCs was measured by using the Illumina Infinium HumanMethylation450 BeadChip. Total IgE levels were measured by using the UniCAP 100 system. In PR-GOAL WBC types (ie, neutrophils, eosinophils, basophils, lymphocytes, and monocytes) in peripheral blood were measured by using Coulter Counter techniques. In the GALA II study WBC types were imputed. Multivariable linear regression was used for the analysis of DNA methylation and total IgE levels, which was first conducted separately for each cohort, and then results from the 2 cohorts were combined in a meta-analysis.

RESULTS

CpG sites in multiple genes, including novel findings and results previously reported in white subjects, were significantly associated with total IgE levels. However, adjustment for WBC types resulted in markedly fewer significant sites. Top findings from this adjusted meta-analysis were in the genes ZFPM1 (P = 1.5 × 10^-12), ACOT7 (P = 2.5 × 10^-11), and MND1 (P = 1.4 × 10^-9).

CONCLUSIONS

In an epigenome-wide association study adjusted for WBC types (including eosinophils), methylation changes in genes enriched in pathways relevant to asthma and immune responses were associated with total IgE levels among Hispanic children.

Evaluation of the eosinophil-to-lymphocyte ratio in pediatric patients with allergic rhinitis

BACKGROUND

Allergic rhinitis is a type 1 hypersensitivity reaction of the nasal mucosa, the primary mediator of which is immunoglobulin E. Allergic rhinitis occurs in children and adolescents.

OBJECTIVE

This study examined the relationship between allergies and the eosinophil-to-lymphocyte ratio in children with allergic rhinitis with a positive skin-prick test.

STUDY DESIGN

This study was planned and performed as a case-control study.

METHODS

There were 695 patients who presented to our clinic who were enrolled in the study. Only group 4 fit the criteria for allergic rhinitis. Group 1 (nonsensitized asymptomatic [control group]), group 2 (nonsensitized symptomatic), group 3 (sensitized asymptomatic), and group 4 (sensitized symptomatic). The patients' allergy symptoms and skin test results were assessed and compared. The eosinophil-to-lymphocyte ratio for each patient was calculated. The eosinophil and lymphocyte counts and the eosinophil-to-lymphocyte ratio were calculated for each group.

RESULTS

The eosinophil-to-lymphocyte ratio and eosinophil counts in groups 3 and 4 were significantly higher (p < 0.001 and p < 0.001, respectively) than those in groups 1 and 2. The lymphocyte counts in groups 3 and 4 were significantly lower (p = 0.046) than those of groups 1 and 2.

CONCLUSIONS

The eosinophil-to-lymphocyte ratio may be used in conjunction with skin-prick testing in pediatric patients with allergic rhinitis. This parameter is inexpensive to measure and easy to use and calculate.

RhoH is a negative regulator of eosinophilopoiesis

Eosinophils are frequently elevated in pathological conditions and can cause tissue damage and disease exacerbation. The number of eosinophils in the blood is largely regulated by factors controlling their production in the bone marrow. While several exogenous factors, such as interleukin-5, have been described to promote eosinophil differentiation, comparatively little is known about eosinophil-intrinsic factors that control their de novo generation. Here, we report that the small atypical GTPase RhoH is induced during human eosinophil differentiation, highly expressed in mature blood eosinophils and further upregulated in patients suffering from a hypereosinophilic syndrome. Overexpression of RhoH increases, in a Rho-associated protein kinase-dependent manner, the expression of GATA-2, a transcription factor involved in regulating eosinophil differentiation. In RhoH^-/- mice, we observed reduced GATA-2 expression as well as accelerated eosinophil differentiation both in vitro and in vivo. Conversely, RhoH overexpression in bone marrow progenitors reduces eosinophil development in mixed bone marrow chimeras. These results highlight a novel negative regulatory role for RhoH in eosinophil differentiation, most likely in consequence of altered GATA-2 levels.

Association of serum eosinophilia and total immunoglobulin E concentration with the risk of allergic symptoms and allergic sensitization, respectively: A 2-year follow-up study

OBJECTIVES

Serum eosinophil percentage (SEP), eosinophil cationic protein (ECP) concentration, and total IgE (TIgE) concentration are known to increase in patients with allergic disease; however, the relevance of these elevated markers in children with negative allergic test results remains unclear. Therefore, this 2-year follow-up study aimed to investigate whether SEP, ECP concentration, and TIgE concentration are associated with an increased risk for allergic sensitization and allergic symptoms.

METHODS

In 2012, SEP, ECP concentration, and TIgE concentration of third- and fourth-grade students from 6 elementary schools were measured. Skin prick test was performed, and the presence of allergic nasal symptoms was investigated using a questionnaire. In 2014, the same examinations were performed in the same set of students, who were then in the fifth and sixth grades, respectively, of the same schools. The cut-off value and usefulness of serologic markers (eosinophil count, ECP concentration, and TIgE concentration) were calculated using the receiver operating characteristic curve.

RESULTS

Serum eosinophil percentage (cut-off value, 3.8%) was associated with the newly developed allergic nasal symptoms (sensitivity, 77.9; specificity, 41.8). A high serum TIgE concentration (cut-off value, 17.7 IU/mL) was also associated with the risk for allergic sensitization (sensitivity, 46.3; specificity, 85.3).

CONCLUSION

SEP and TIgE concentration were associated with the development of allergic symptoms and allergic sensitization, respectively, 2 years after the first examination.

Cannabinoid receptor 2 augments eosinophil responsiveness and aggravates allergen-induced pulmonary inflammation in mice

Background

Accumulation of activated eosinophils in tissue is a hallmark of allergic inflammation. The endocannabinoid 2‐arachidonoylglycerol (2‐AG) has been proposed to elicit eosinophil migration in a CB₂ receptor/G_i/o‐dependent manner. However, it has been claimed recently that this process may also involve other mechanisms such as cytokine priming and the metabolism of 2‐AG into eicosanoids. Here, we explored the direct contribution of specific CB₂ receptor activation to human and mouse eosinophil effector function in vitro and in vivo.

Methods

In vitro studies including CB₂ expression, adhesion and migratory responsiveness, respiratory burst, degranulation, and calcium mobilization were conducted in human peripheral blood eosinophils and mouse bone marrow‐derived eosinophils. Allergic airway inflammation was assessed in mouse models of acute OVA‐induced asthma and directed eosinophil migration.

Results

CB₂ expression was significantly higher in eosinophils from symptomatic allergic donors. The selective CB₂ receptor agonist JWH‐133 induced a moderate migratory response in eosinophils. However, short‐term exposure to JWH‐133 potently enhanced chemoattractant‐induced eosinophil shape change, chemotaxis, CD11b surface expression, and adhesion as well as production of reactive oxygen species. Receptor specificity of the observed effects was confirmed in eosinophils from CB₂ knockout mice and by using the selective CB₂ antagonist SR144528. Of note, systemic application of JWH‐133 clearly primed eosinophil‐directed migration in vivo and aggravated both AHR and eosinophil influx into the airways in a CB₂‐specific manner. This effect was completely absent in eosinophil‐deficient ∆dblGATA mice.

Conclusion

Our data indicate that CB₂ may directly contribute to the pathogenesis of eosinophil‐driven diseases. Moreover, we provide new insights into the molecular mechanisms underlying the CB₂‐mediated priming of eosinophils. Hence, antagonism of CB₂ receptors may represent a novel pharmacological approach for the treatment of allergic inflammation and other eosinophilic disorders.

Eosinophilic gastrointestinal disorders associated with autoimmune connective tissue disease

OBJECTIVES

To determine the clinical and pathological characteristics of eosinophilic gastrointestinal disease (EGID) associated with autoimmune connective tissue disease (CTD).

METHODS

Systematic literature review.

RESULTS

Twenty cases of CTD associated with EGID were identified. Systemic lupus erythematosus was the main EGID-associated CTD (35%), followed by rheumatoid arthritis (20%), systemic sclerosis or inflammatory myopathies (15%, each), and Sjögren's syndrome, scleromyositis or other overlapping connective tissue disease (5%, each). No patient had a history of atopy. In contrast with classical EGID among which eosinophilic esophagitis is the most frequent type, eosinophilic gastritis and/or enteritis represented 95% of cases. Gastrointestinal symptoms were often unspecific. Peripheral eosinophilia was found in 67% of cases. Upper and lower gastrointestinal endoscopy showed abnormal findings in only 40% and 30% of cases, respectively. EGID was confirmed by evidence of digestive eosinophilic infiltration, mainly in mucosal or submucosal layer. In all but one patient, the CTD was diagnosed prior to the occurrence of the EGID. In total, 95% of EGID had a favorable outcome, with corticosteroids being used in almost all cases.

CONCLUSION

Clinicians should consider EGID as a possible diagnosis and perform gastrointestinal tract biopsies in patients with CTD presenting with gastrointestinal symptoms and unexplained eosinophilia. Conversely, more rarely extra-digestive features during follow-up in patients with EGID may lead to a diagnosis of an associated CTD. More research is needed to better understand the underlying pathophysiological processes leading to eosinophilic gastrointestinal infiltration in patients with CTD.

Eosinophilia in Dermatologic Disorders

Eosinophil infiltration can be observed in skin disorders, such as allergic/immunologic, autoimmune, infectious, and neoplastic diseases. Clinical presentations are variable and include eczematous, papular, urticarial, bullous, nodular, and fibrotic lesions; pruritus is a common symptom in all. In this review, we present representative eosinophilic skin diseases according to their clinical pattern, together with histologic findings and diagnostic procedures. We also discuss the potential roles of eosinophils in the pathogenesis of dermatologic disorder. Current pathogenesis-based diagnostic and therapeutic approaches are outlined.

Toxicity of eosinophil MBP is repressed by intracellular crystallization and promoted by extracellular aggregation

Eosinophils are white blood cells that function in innate immunity and participate in the pathogenesis of various inflammatory and neoplastic disorders. Their secretory granules contain four cytotoxic proteins, including the eosinophil major basic protein (MBP-1). How MBP-1 toxicity is controlled within the eosinophil itself and activated upon extracellular release is unknown. Here we show how intragranular MBP-1 nanocrystals restrain toxicity, enabling its safe storage, and characterize them with an X-ray-free electron laser. Following eosinophil activation, MBP-1 toxicity is triggered by granule acidification, followed by extracellular aggregation, which mediates the damage to pathogens and host cells. Larger non-toxic amyloid plaques are also present in tissues of eosinophilic patients in a feedback mechanism that likely limits tissue damage under pathological conditions of MBP-1 oversecretion. Our results suggest that MBP-1 aggregation is important for innate immunity and immunopathology mediated by eosinophils and clarify how its polymorphic self-association pathways regulate toxicity intra- and extracellularly.

Novel targeted therapies for eosinophil-associated diseases and allergy

Eosinophil-associated diseases often present with life-threatening manifestations and/or chronic organ damage. Currently available therapeutic options are limited to a few drugs that often have to be prescribed on a lifelong basis to keep eosinophil counts under control. In the past 10 years, treatment options and outcomes in patients with clonal eosinophilic and other eosinophilic disorders have improved substantially. Several new targeted therapies have emerged, addressing different aspects of eosinophil expansion and inflammation. In this review, we discuss available and currently tested agents as well as new strategies and drug targets relevant to both primary and secondary eosinophilic diseases, including allergic disorders.

Is chronic asthma associated with shorter leukocyte telomere length at midlife?

RATIONALE

Asthma is prospectively associated with age-related chronic diseases and mortality, suggesting the hypothesis that asthma may relate to a general, multisystem phenotype of accelerated aging.

OBJECTIVES

To test whether chronic asthma is associated with a proposed biomarker of accelerated aging, leukocyte telomere length.

METHODS

Asthma was ascertained prospectively in the Dunedin Multidisciplinary Health and Development Study cohort (n = 1,037) at nine in-person assessments spanning ages 9-38 years. Leukocyte telomere length was measured at ages 26 and 38 years. Asthma was classified as life-course-persistent, childhood-onset not meeting criteria for persistence, and adolescent/adult-onset. We tested associations between asthma and leukocyte telomere length using regression models. We tested for confounding of asthma-leukocyte telomere length associations using covariate adjustment. We tested serum C-reactive protein and white blood cell counts as potential mediators of asthma-leukocyte telomere length associations.

MEASUREMENTS AND MAIN RESULTS

Study members with life-course-persistent asthma had shorter leukocyte telomere length as compared with sex- and age-matched peers with no reported asthma. In contrast, leukocyte telomere length in study members with childhood-onset and adolescent/adult-onset asthma was not different from leukocyte telomere length in peers with no reported asthma. Adjustment for life histories of obesity and smoking did not change results. Study members with life-course-persistent asthma had elevated blood eosinophil counts. Blood eosinophil count mediated 29% of the life-course-persistent asthma-leukocyte telomere length association.

CONCLUSIONS

Life-course-persistent asthma is related to a proposed biomarker of accelerated aging, possibly via systemic eosinophilic inflammation. Life histories of asthma can inform studies of aging.

Diagnosis of primary pulmonary T- cell/histiocyte-rich large B cell lymphoma with tissue eosinophilia via clinicopathological observation and molecular assay

Background

Primary pulmonary lymphoma (PPL) is rare and easily misdiagnosed because of the lack of typical clinical features. It most commonly involves elderly patients aged between 60 and 70 years, and pathological diagnosis depends mainly on chest surgery rather than bronchial mucosal biopsy. Via percutaneous needle aspiration biopsy of the lung of a 33-year-old woman, which had distinct tissue eosinophilia, we diagnosed a rare case of rapidly growing large B cell lymphoma.

Methods

Bronchial mucosal biopsy and computed tomography–guided percutaneous needle aspiration biopsy were performed to determine the nature of the lesion, and we identified its immunophenotype using immunohistochemistry. We used BIOMED-2 gene rearrangement PCR to determine lymphocyte clonality; laser microdissection was used to confirm the clonality of suspicious malignant lymphocytes.

Results

Morphologically, the lesion was composed of a large number of eosinophilic cells and a few lymphoid cells. Immunohistochemical staining revealed a few CD1α-positive cells, but they were S-100–negative. The small lymphoid cells predominantly expressed CD3; the large lymphoid cells expressed CD20 and some scattered large lymphoid cells expressed Pax5. However, molecular studies confirmed clonal immunoglobulin heavy chain (IGH)-D gene rearrangement in Pax5–positive large B lymphocytes.

Conclusions

This is the first recorded case of T- cell/histiocyte-rich large B cell lymphoma with tissue eosinophilia of the lung. It highlights the unusual morphological features of PPL that might be mistaken for eosinophilic granuloma or parasitic infection. In addition, IGH and T cell receptor gene rearrangement play important roles in differentiating rare B cell lymphoma from lung space–occupying lesions with abundant eosinophils or T cell infiltration.

Virtual Slides

The virtual slide(s) for this article can be found here: http://med.motic.com/MoticGallery/Slides/AC5C9A6F-46EC-4C71-A448-1312F6900C65?user=2C69F0D6-A478-4A2B-ABF0-BB36763E8025

Immunopathogenesis of eosinophilic esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the esophagus associated with dysphagia in adults and refractory reflux syndromes in children.

METHODS

Immunological and genetic approaches have been used to better understand the pathophysiology of the underlying inflammation.

RESULTS AND CONCLUSIONS

Evidence has accumulated that EoE represents a T-helper (Th) 2-type inflammatory disease, in which allergens play a role in triggering the disease. The majority of the patients suffer from concurrent allergic rhinitis, asthma, and eczema, and have a history of atopy. The chronic inflammatory response in EoE is associated with tissue damage and remodeling, both of which lead to esophageal dysfunction and bolus impaction. The new insights into the pathophysiology have resulted in the development of the first pharmacological therapies of EoE.

CD8(+) T cells producing IL-3 and IL-5 in non-IgE-mediated eosinophilic diseases

The cytokines IL-5, IL-3, and GM-CSF are crucial for eosinophil development, survival, and function. To better understand their role in non-IgE-mediated eosinophilic diseases, we investigated plasma levels of these cytokines as well as cytokine expression in peripheral blood T cells. While we did not find any evidence for an involvement of T-cell-derived GM-CSF, some of these patients did show an increased proportion of IL-5- or IL-3-producing CD4(+) T cells. However, in a significant proportion of patients, IL-5-producing CD8(+) T cells, so-called Tc2 cells, which in healthy donors can only be detected at very low levels, were prominent. Furthermore, increased IL-3 production by CD8(+) T cells was also observed, strongly supporting the notion that CD8(+) T cells, not just CD4(+) T cells, must also be considered as a potential source of the cytokines promoting eosinophilia.