Mechanisms of eosinophilia in the pathogenesis of hypereosinophilic disorders

Insights into the biology of the rat lungworm, Angiostrongylus cantonensis

Angiostrongylus cantonensis is a parasitic nematode with a complex life cycle involving rats as definitive hosts and gastropods as intermediate hosts. The parasite can infect other organisms, including humans, in which it causes neuroangiostrongyliasis, a globally emerging but neglected disease. This primer reviews the biology of A. cantonensis including its life cycle and development in its natural, accidental, and paratenic hosts, as well as its expanding geographic distribution. It then considers recent advances in A. cantonensis research followed by exploring areas that are ripe for further investigation into this fascinating parasite.

Severe conjunctival allergic reaction to polyglactin 910 sutures following strabismus surgery: A case report

INTRODUCTION AND IMPORTANCE

Polyglactin 910 sutures are commonly used in strabismus surgery due to their favorable handling and absorption qualities. However, their potential to cause allergic reactions is poorly documented in medical literature. This case report emphasizes this rare complication, stressing the importance of promptly recognizing and managing such reactions to ensure optimal patient outcomes.

CASE PRESENTATION

An 11-year-old girl with a history of left congenital partial third nerve palsy was treated with 8-0, polyglactin 910 sutures during a strabismus surgery. However, two days postoperatively, she experienced persistent redness, swelling, and pain in her left eye despite antibiotic therapy. After six days, the sutures were removed, resulting in an immediate reduction in symptoms. By the two-month follow-up, the patient fully recovered, with no signs of inflammation or complications.

CLINICAL DISCUSSION

This case highlights a rare but crucial allergic reaction to polyglactin 910 sutures used in strabismus surgery. The patient's persistent inflammation, pain, and resistance to antibiotics indicated a localized allergic reaction, rather than an infection. The prompt resolution of symptoms after suture removal supports the diagnosis of suture-related allergic reaction. This case emphasizes the need to consider suture material as a potential cause of postoperative complications, especially when standard treatment fails.

CONCLUSION

Healthcare providers should be alert to potential allergic reactions to sutures after strabismus surgery. Timely identification and removal are vital for resolving the symptoms and achieving optimal patient outcomes. This case emphasizes the importance of postoperative care protocols that consider allergies to suture material.

Successful treatment of eosinophilia associated with dialysis-related renal cancer with radical nephrectomy

Introduction

Secondary eosinophilia due to solid tumors is a rare case. This is the first study to report secondary eosinophilia due to renal cancer in a patient on dialysis.

Case presentation

A 70-year-old man, on long-term hemodialysis was incidentally detected with right renal cancer, and workup performed revealed eosinophilia. Allergic symptoms caused by hemodialysis were initially considered; however, treatment did not lead to any improvement in eosinophilia. Therefore, nephrectomy for renal cancer was performed. The resolution of symptoms and eosinophilia after surgery suggested renal cancer as the cause of eosinophilia.

Conclusion

As demonstrated in this patient with dialysis-related renal cancer, eosinophilia associated with solid tumors may be addressed by treating the tumor.

An Unusual Case of Immune Complex-Mediated Membranoproliferative Glomerulonephritis as Renal Manifestation of Idiopathic Hypereosinophilic Syndrome: A Case Report and Literature Review

BACKGROUND

Idiopathic hypereosinophilic syndrome (IHES) is a disorder characterized by abnormal and persistent peripheral blood hypereosinophilia (eosinophil count ≥ 1.5 × 109/L and ≥10% eosinophils) with duration ≥ 6 months, associated organ damage, and/or dysfunction attributable to tissue eosinophilic infiltrate of unknown cause. IHES affects different organs such as the heart, lungs, nervous system, and skin, with renal involvement being rare in this condition.

CASE PRESENTATION

We present a case of a young patient with IHES and immune complex-mediated membranoproliferative glomerulonephritis with nephrotic syndrome, as a rare renal manifestation. We discuss the clinical, analytical, and histopathologic renal and hematologic features, comparing them with other reported cases in the literature.

Clinical and Therapeutic Intervention of Hypereosinophilia in the Era of Molecular Diagnosis

Hypereosinophilia (HE) presents with an elevated peripheral eosinophilic count of >1.5 × 109/L and is composed of a broad spectrum of secondary non-hematologic disorders and a minority of primary hematologic processes with heterogenous clinical presentations, ranging from mild symptoms to potentially lethal outcome secondary to end-organ damage. Following the introduction of advanced molecular diagnostics (genomic studies, RNA sequencing, and targeted gene mutation profile, etc.) in the last 1-2 decades, there have been deep insights into the etiology and molecular mechanisms involved in the development of HE. The classification of HE has been updated and refined following to the discovery of clinically novel markers and targets in the 2022 WHO classification and ICOG-EO 2021 Working Conference on Eosinophil Disorder and Syndromes. However, the diagnosis and management of HE is challenging given its heterogeneity and variable clinical outcome. It is critical to have a diagnostic algorithm for accurate subclassification of HE and hypereosinophilic syndrome (HES) (e.g., reactive, familial, idiopathic, myeloid/lymphoid neoplasm, organ restricted, or with unknown significance) and to follow established treatment guidelines for patients based on its clinical findings and risk stratification.

Critical deterioration of chronic eosinophilic pneumonia during pregnancy

Chronic eosinophilic pneumonia (CEP) is a rare, idiopathic interstitial lung disease characterised by the accumulation of eosinophils in the pulmonary interstitia and alveoli. Patients with CEP respond well to systemic corticosteroid therapy and infrequently progress to end-stage lung disease. We report a case of a woman in her 40s with previously stable, steroid-responsive CEP who experienced a critical deterioration of her CEP at 25 weeks of gestation during her third pregnancy. The patient was admitted to the intensive care unit due to respiratory failure requiring intubation and mechanical ventilation. Follow-up investigation revealed advanced fibrotic lung disease requiring long-term oxygen therapy and referral for double lung transplantation. While CEP infrequently advances to permanent parenchymal damage, this case demonstrates the potential for severe exacerbations in the setting of pregnancy and highlights pregnancy as a potential risk factor for disease progression, reinforcing the need for further research to define optimal monitoring and treatment strategies.

An algorithm-based approach to ascertain patients with rare diseases in electronic health records using hypereosinophilic syndrome as an example

PURPOSE

Improved hypereosinophilic syndrome (HES) ascertainment in electronic health record (EHR) databases may improve disease understanding and management. An algorithm to ascertain and characterize this rare condition was therefore developed and validated.

METHODS

Using the UK clinical practice research datalink (CPRD)-Aurum database linked to the hospital episode statistics database (Admitted Patient Care data) from Jan 2012 to June 2019, this cross-sectional study ascertained patients with a specific HES code (index). Patients with HES were matched (age, sex and index date) 1:29 with a non-HES cohort. An algorithm was developed by identifying pre-defined variables differing between cohorts; model-fitting using Firth logistic regression and statistical determination of the top-five performing models; and internal validation using Leave-One-Out Cross Validation. Final model sensitivity and specificity were determined at an 80% probability threshold.

RESULTS

The HES and non-HES cohorts included 88 and 2552 patients, respectively; 270 models with four variables each (treatment used for HES, asthma code, white blood cell condition code, and blood eosinophil count [BEC] code) plus age and sex variables were tested. Of the top five models, the sensitivity model performed best (sensitivity, 69% [95% CI: 59%, 79%]; specificity, >99%). The strongest predictors of HES versus non-HES cases (odds >1000 times greater) were an ICD-10 code for white blood cell disorders and a BEC ≥1500 cells/μL in the 24 months pre-index.

CONCLUSIONS

Using a combination of medical codes, prescribed treatments data and laboratory results, the algorithm can help ascertain patients with HES from EHR databases; this approach may be useful for other rare diseases.

Who Let the Dogs Out? Unmasking the Neglected: A Semi-Systematic Review on the Enduring Impact of Toxocariasis, a Prevalent Zoonotic Infection

Toxocariasis remains an important neglected parasitic infection representing one of the most common zoonotic infections caused by the parasite Toxocara canis or, less frequently, by Toxocara cati. The epidemiology of the disease is complex due to its transmission route by accidental ingestion of embryonated Toxocara eggs or larvae from tissues from domestic or wild paratenic hosts. Even though the World Health Organization and Centers for Disease Control classified toxocariasis amongst the top six parasitic infections of priority to public health, global epidemiological data regarding the relationship between seropositivity and toxocariasis is limited. Although the vast majority of the infected individuals remain asymptomatic or experience a mild disease, the infection is associated with important health and socioeconomic consequences, particularly in underprivileged, tropical, and subtropical areas. Toxocariasis is a disease with multiple clinical presentations, which are classified into five distinct forms: the classical visceral larva migrans, ocular toxocariasis, common toxocariasis, covert toxocariasis, and cerebral toxocariasis or neurotoxocariasis. Anthelmintic agents, for example, albendazole or mebendazole, are the recommended treatment, whereas a combination with topical or systemic corticosteroids for specific forms is suggested. Prevention strategies include educational programs, behavioral and hygienic changes, enhancement of the role of veterinarians, and anthelmintic regimens to control active infections.

GEMA 5.3. Spanish Guideline on the Management of Asthma

The Spanish Guideline on the Management of Asthma, better known by its acronym in Spanish GEMA, has been available for more than 20 years. Twenty-one scientific societies or related groups both from Spain and internationally have participated in the preparation and development of the updated edition of GEMA, which in fact has been currently positioned as the reference guide on asthma in the Spanish language worldwide. Its objective is to prevent and improve the clinical situation of people with asthma by increasing the knowledge of healthcare professionals involved in their care. Its purpose is to convert scientific evidence into simple and easy-to-follow practical recommendations. Therefore, it is not a monograph that brings together all the scientific knowledge about the disease, but rather a brief document with the essentials, designed to be applied quickly in routine clinical practice. The guidelines are necessarily multidisciplinary, developed to be useful and an indispensable tool for physicians of different specialties, as well as nurses and pharmacists. Probably the most outstanding aspects of the guide are the recommendations to: establish the diagnosis of asthma using a sequential algorithm based on objective diagnostic tests; the follow-up of patients, preferably based on the strategy of achieving and maintaining control of the disease; treatment according to the level of severity of asthma, using six steps from least to greatest need of pharmaceutical drugs, and the treatment algorithm for the indication of biologics in patients with severe uncontrolled asthma based on phenotypes. And now, in addition to that, there is a novelty for easy use and follow-up through a computer application based on the chatbot-type conversational artificial intelligence (ia-GEMA).

Gene Therapy for Immunoglobulin E, Complement-Mediated, and Eosinophilic Disorders

Immunoglobulin E, complement, and eosinophils play an important role in host defense, but dysfunction of each of these components can lead to a variety of human disorders. In this review, we summarize how investigators have adapted gene therapy and antisense technology to modulate immunoglobulin E, complement, and/or eosinophil levels to treat these disorders.

Case report: Probable toxocariasis in a Swiss adult patient with hypereosinophilic syndrome and multiorgan involvement

Hypereosinophilic syndromes are a heterogeneous group of rare diseases characterized by eosinophil-related organ damage and peripheral blood hypereosinophilia. Hypereosinophilic syndromes may occur secondary to a variety of clinical entities, for example, drug hypersensitivity reactions, parasitic infections, autoimmune disorders, and malignancies. Toxocariasis is a parasitic infection caused by the larval stage of the Toxocara species. It is usually a childhood disease and invades organs such as the liver but can affect any organ. Hypereosinophilic syndrome and multiorgan involvement are very rare manifestations of Toxocara infection, especially in adults. However, the disease may be underdiagnosed because of different factors, including a lack of laboratory infrastructure in some countries, a lack of uniform case definitions, and limited surveillance infrastructure, with its estimation constituting a challenge. We, therefore, present a probable case of hypereosinophilic syndrome with multiorgan involvement secondary to infection with Toxocara canis in a 79-year-old Swiss female patient with a medical history of ischemic cerebrovascular insult and a curatively resected non-small-cell bronchial carcinoma, successfully treated with albendazole and steroids.

FIP1L1-PDGFRA Clonal Hypereosinophilic Syndrome With Eosinophilic Myocarditis and Intracardiac Thrombus

A 45-year-old man from El Salvador with no past medical history presented with cough and chest pain. Investigations revealed 60% peripheral eosinophilia (absolute count 12.3 K/uL). Cardiac imaging was consistent with myocarditis with intracardiac thrombus formation. Endomyocardial biopsy confirmed eosinophilic infiltration of the myocardium, and bone marrow biopsy showed hypercellular marrow with 28% eosinophils. Cytogenetics/fluorescence in situ hybridization (FISH) confirmed positive FIP1L1-PDGFRA rearrangement. The patient was treated for FIP1L1-PDGFRA clonal hypereosinophilic syndrome with associated eosinophilic myocarditis and intracardiac thrombus. The treatment regimen consisted of a steroid taper, imatinib, and anticoagulation. Treatment was followed by normalization of the eosinophil count. At two-year follow-up, the patient was without recurrence of eosinophilia on maintenance imatinib and indefinite anticoagulation with warfarin.

HES and EGPA: Two Sides of the Same Coin

Elevated eosinophil counts are implicated in multiple diseases, from relatively prevalent organ-specific disorders such as severe eosinophilic asthma, to rare multisystem disorders such as hypereosinophilic syndrome (HES) and eosinophilic granulomatosis with polyangiitis (EGPA). Patients with these multisystem diseases, often associated with markedly elevated eosinophil counts, have a substantial risk of morbidity and mortality due to delayed diagnosis or inadequate treatment. A thorough workup of symptomatic patients presenting with elevated eosinophil counts is essential, although in some cases the differential diagnosis may remain difficult because of overlapping presentations between HES and EGPA. Notably, first- and second-line treatment options and response to therapy may differ for specific HES and EGPA variants. Oral corticosteroids are the first line of treatment for HES and EGPA, except when HES is the result of specific mutations driving clonal eosinophilia that are amenable to targeted treatment with a kinase inhibitor. Cytotoxic or immunomodulatory agents may be required for those with severe disease. Novel eosinophil-depleting therapies, such as those targeting interleukin 5 or its receptor, have shown great promise in reducing blood eosinophil counts, and reducing disease flares and relapses in patients with HES and EGPA. Such therapies could reduce the side effects associated with long-term oral corticosteroids or immunosuppressant use. This review provides a pragmatic guide to approaching the diagnosis and clinical management of patients with systemic hypereosinophilic disorders. We highlight practical considerations for clinicians and present cases from real-world clinical practice to show the complexity and challenges associated with diagnosing and treating patients with HES and EGPA.

The hypereosinophilic syndrome - an unusual cause of myocarditis and cardioembolic strokes

Hypereosinophilic syndrome is a rare disorder characterized by excessive peripheral eosinophilia and eosinophil associated end-organ damage. Clinical presentations are heterogenous and can involve skin, pulmonary, cardiac and neurologic dysfunction. Eosinophilic myocarditis is a life-threatening complication that increases the risk of cardiac microemboli, which can subsequently lead to embolic strokes. Secondary to changes in blood viscosity, impaired clearance of microemboli, impaired cerebral blood flow, and pro-thrombotic conditions in the setting of hypereosinophilia, infarcts often present in vascular border zone regions. Here we present two cases of cardioembolic strokes involving borderzone regions in the setting of hypereosinophilic syndrome.

Clinical Profile and Treatment in Hypereosinophilic Syndrome Variants: A Pragmatic Review

BACKGROUND

Hypereosinophilic syndrome (HES) is a group of rare hematologic disorders leading to eosinophil-driven tissue damage and dysfunction. Better understanding of HES variants may facilitate improved patient management.

OBJECTIVE

To describe disease characteristics, treatment, and outcomes of patients with idiopathic (I-HES), myeloproliferative (M-HES), lymphocytic (L-HES), and chronic eosinophilic leukemia, not otherwise specified (CEL-NOS) among HES case reports and aggregate data where available.

METHODS

Relevant articles published between January 1, 2000, and March 20, 2020, were retrieved via PubMed; those reporting secondary, associated/reactive, overlap/single-organ, or familial HES were excluded.

RESULTS

Of 188 articles included, 171 contained data on 347 separate HES cases (152 I-HES, 121 M-HES, 62 L-HES, 12 CEL-NOS). Based on individual data, mean age at diagnosis was 43 to 48 years for patients with all HES variants. Males accounted for 90% to 91% of M-HES/CEL-NOS and 55% to 65% of I-HES/L-HES cases. Cardiac symptoms were frequently observed for all HES variants (13%-22% of patients). Respiratory symptoms (I-HES), splenomegaly (M-HES and CEL-NOS), and skin conditions (L-HES) were also frequently observed. Bone marrow, heart, lung, spleen, liver, skin, and lymph nodes were commonly involved. Most patients with I-HES, L-HES, and CEL-NOS received corticosteroids (65%-85%), whereas most with M-HES received imatinib (81%); those with CEL-NOS also received interferon alpha (42%).

CONCLUSIONS

Collective analysis of HES case reports supports and extends current understanding of HES variants, highlighting differences in signs and symptoms, organ involvement, and treatment approaches. Improved characterization of HES variants may facilitate the development of novel treatments.

A Unique Case of Cardiac Hypereosinophilia With Recurrent Valve Thrombosis After Mechanical Mitral Valve Replacement in the Setting of a Supratherapeutic International Normalized Ratio

Hypereosinophilia (HES) is a rare, but highly fatal, disease that results in excess eosinophils causing multiorgan damage, mainly manifesting as extensive inflammation contributing to fibrosis. Notably, cardiac involvement occurs in almost half the cases and can often lead to thrombus development. This is a unique case of HES contributing to recurrent cardiac thrombus formation on a mechanical mitral valve in the setting of a patient who had a supratherapeutic international normalized ratio (INR) while on coumadin. The rarity of this case is also displayed in the patient’s negativity for one of the fusion genes that are highly suggestive of cardiac HES, the demographics of her female gender, and her first objective sign being T-wave inversions versus the usual heart failure signs and symptoms. This case raises awareness of the disorder but also the importance of keeping its potential exacerbations on the differential, even in the setting of atypical presentations. With this, it also begs the question of whether coumadin is the proper anticoagulant of choice in these patients and whether other parameters should be considered.

The role of cardiovascular magnetic resonance in the evaluation of acute myocarditis and inflammatory cardiomyopathies in clinical practice - a comprehensive review

Inflammatory cardiomyopathy (I-CMP) is defined as myocarditis in association with cardiac dysfunction and/or ventricular remodelling. It is characterized by inflammatory cell infiltration into the myocardium and has heterogeneous infectious and non-infectious aetiologies. A complex interplay of genetic, autoimmune, and environmental factors contributes to the substantial risk of deteriorating cardiac function, acute heart failure, and arrhythmia as well as chronic dilated cardiomyopathy and its sequelae. Multi-parametric cardiovascular magnetic resonance (CMR) imaging is sensitive to many tissue changes that occur during myocardial inflammation, regardless of its aetiology. In this review, we summarize the various aetiologies of I-CMP and illustrate how CMR contributes to non-invasive diagnosis.

Modulating ILC2 function for treatment of type 2 airway diseases

Type 2 airway diseases including chronic rhinosinusitis, allergic rhinitis, and asthma remain a major health concern. These disorders are largely characterized by an uncontrolled type 2 immune response with elevated cytokines of IL-4, IL-5 and IL-13, eosinophilic inflammation, goblet cell hyperplasia as well as tissue remodeling. In the last few decades, critical potential roles of innate lymphoid cells (ILCs) in type 2 human diseases have emerged. Unlike their lymphocyte counterpart T cells, ILCs lack antigen-specific receptors and are largely tissue resident. Specifically, group 2 innate lymphoid cells (ILC2s) respond to airway epithelium-derived alarmins (TSLP, IL-33) and secrete high levels of type 2 cytokines. ILC2 responses can bypass the activation of T cells as well as develop corticosteroid-resistance. Currently approved biologics targeting the alarmin thymic stromal lymphopoietin (TSLP) or the IL-4/IL-13 receptor may reduce ILC2 activation, though novel treatments of type 2 airway diseases remain needed. In this review, we briefly discuss the pathogenesis of ILC2-mediated airway diseases followed by their current and potential treatments.

Amelioration of Alzheimer's Disease by Gut-Pancreas-Liver-Brain Interaction in an App Knock-In Mouse Model

In this study, we observed disease progression, changes in the gut microbiota, and interactions among the brain, liver, pancreas, and intestine in a mouse model of Alzheimer's disease (AD), in addition to attempting to inhibit disease progression through the dietary supplementation of L-arginine and limonoids. Wild-type mice (WC) and AD mice were fed a normal diet (AC), a diet supplemented with L-arginine and limonoids (ALA), or a diet containing only limonoids (AL) for 12-64 weeks. The normal diet-fed WC and AC mice showed a decrease in the diversity of the gut microbiota, with an increase in the Firmicutes/Bacteroidetes ratio, and bacterial translocation. Considerable bacterial translocation to the pancreas and intense inflammation of the pancreas, liver, brain, and intestinal tissues were observed in the AC mice from alterations in the gut microbiota. The ALA diet or AL diet-fed mice showed increased diversity of the bacterial flora and suppressed oxidative stress and inflammatory responses in hepatocytes and pancreatic cells, bacterial translocation, and neurodegeneration of the brain. These findings suggest that L-arginine and limonoids help in maintaining the homeostasis of the gut microbiota, pancreas, liver, brain, and gut in AD mice.

The increasing incidence and prevalence of hypereosinophilic syndrome in the United Kingdom

Introduction

Data on the burden of hypereosinophilic syndrome (HES) are limited. This study investigated the incidence and prevalence of HES using real‐world data from patients in the United Kingdom.

Methods

Primary care data from the Clinical Practice Research Datalink were analyzed. The patients of interest were identified using medical codes specific for HES. Annual incidence rates and prevalence were estimated for the years 2010–2018 (inclusive) using patients observed for a minimum period of one year.

Results

Between 2010 and 2018, 93 patients were identified with HES. During the study period the incidence of HES ranged from less than 0.04, 95% confidence interval (CI) (0.01–0.07) to 0.17, 95% CI (0.10–0.26) per 100,000 person‐years and the prevalence ranged from 0.15, 95% CI (0.10–0.25) to 0.89, 95% CI (0.74–1.09) cases per 100,000 persons. Sensitivity analyses varying the minimum observation period required to identify HES patients gave similar results.

Conclusion

These results provide estimates of the burden of HES in the United Kingdom and indicate that whilst HES is a very rare disease, there is evidence that is increasingly being recorded in UK primary care.

Eosinophilic pancreatitis: a review of the pathophysiology, diagnosis, and treatment

Eosinophilic pancreatitis (EP) is an extremely rare disease caused by purely eosinophilic infiltration of the pancreas. EP is prone to being misdiagnosed as pancreatic cancer, causing unnecessary economic and physical harm to the patient. We report three cases of EP that were cured by steroids without relapse from 2017 to now. The clinical data of the three patients, including clinical manifestations, serological manifestations, imaging (ultrasound, computed tomography, and MRI), pathological diagnosis and treatment, and telephone follow-up of all patients, were retrospectively analysed. In addition, a literature search was conducted on the Web of Science and PubMed databases using key terms related to EP, considering case reports with no restrictions on the date of publication or language. In conclusion, we analysed 19 cases and determined the diagnostic criteria for EP. The diagnostic algorithm for EP can be used to diagnose EP easily. We hope that our standards and algorithm can reduce the rate of misdiagnosis and contribute to clinical diagnosis and treatment. In addition, we expect to evaluate more EP cases to test our diagnostic criteria and design a systematic diagnostic flow chart.

Regulatory eosinophils induce the resolution of experimental arthritis and appear in remission state of human rheumatoid arthritis

OBJECTIVES

Eosinophils possess pro-inflammatory functions in asthma. However, our recent studies have suggested that innate lymphoid cells type 2 (ILC2s) and eosinophils have proresolving properties in rheumatoid arthritis (RA). Nothing is known yet about the mechanisms determining the double-edged role of eosinophils. Therefore, we investigated whether asthma, a paradigm eosinophilic disease, can elicit resolution of chronic arthritis.

METHODS

Ovalbumin-triggered eosinophilic asthma was combined with K/BxN serum-induced arthritis, where lung and synovial eosinophil subsets were compared by single-cell RNA sequencing (scRNA-seq). To investigate the involvement of the ILC2-interleukin-5 (IL-5) axis, hydrodynamic injection (HDI) of IL-25 and IL-33 plasmids, IL-5 reporter mice and anti-IL-5 antibody treatment were used. In patients with RA, the presence of distinct eosinophil subsets was examined in peripheral blood and synovial tissue. Disease activity of patients with RA with concomitant asthma was monitored before and after mepolizumab (anti-IL-5 antibody) therapy.

RESULTS

The induction of eosinophilic asthma caused resolution of murine arthritis and joint tissue protection. ScRNA-seq revealed a specific subset of regulatory eosinophils (rEos) in the joints, distinct from inflammatory eosinophils in the lungs. Mechanistically, synovial rEos expanded on systemic upregulation of IL-5 released by lung ILC2s. Eosinophil depletion abolished the beneficial effect of asthma on arthritis. rEos were consistently present in the synovium of patients with RA in remission, but not in active stage. Remarkably, in patients with RA with concomitant asthma, mepolizumab treatment induced relapse of arthritis.

CONCLUSION

These findings point to a hitherto undiscovered proresolving signature in an eosinophil subset that stimulates arthritis resolution.

Eosinophilic cystitis mimicking bladder cancer-considerations on the management based upon a case report and a review of the literature

The hypereosinophilic syndrome (HES) is a rare disorder characterized by hypereosinophilia and infiltration of various organs with eosinophils. Eosinophilic cystitis (EC), mimicking bladder cancer clinically but also in ultrasound and in radiographic imaging, is one potential manifestation of the HES occurring in adults as well as in children. This case report describes the course of disease in a 57-year-old male presenting with severe gait disorders and symptoms of a low compliance bladder caused by a large retropubic tumor. After extensive urine and serologic examination and histologic confirmation of EC the patient was subjected to medical treatment with cetirizine and prednisolone for 5 weeks. While gait disorders rapidly resolved, micturition normalized only 10 months after initiation of therapy. Based upon this course the authors recommend patience and reluctance concerning radical surgical intervention in EC. Key Points • Eosinophilic cystitis is a rare condition with app. 200 cases reported, so far. • Etiology of eosinophilic cystitis is obscure, but allergies and parasitic infections may trigger the disease. • Genetic alterations (e.g., BRAF mutations) may predispose for the disease • Corticosteroids and antihistamines are the backbone of therapy and may be complemented by antibiotics and non-steroidal anti-inflammatory drugs in case of concomitant (underlying) infections. • As recovery can occur even after a long time, radical surgery should be restricted to highly selected cases.

Molecular Pathogenesis and Treatment Perspectives for Hypereosinophilia and Hypereosinophilic Syndromes

Hypereosinophilia (HE) is a heterogeneous condition with a persistent elevated eosinophil count of >350/mm³, which is reported in various (inflammatory, allergic, infectious, or neoplastic) diseases with distinct pathophysiological pathways. HE may be associated with tissue or organ damage and, in this case, the disorder is classified as hypereosinophilic syndrome (HES). Different studies have allowed for the discovery of two major pathogenetic variants known as myeloid or lymphocytic HES. With the advent of molecular genetic analyses, such as T-cell receptor gene rearrangement assays and Next Generation Sequencing, it is possible to better characterize these syndromes and establish which patients will benefit from pharmacological targeted therapy. In this review, we highlight the molecular alterations that are involved in the pathogenesis of eosinophil disorders and revise possible therapeutic approaches, either implemented in clinical practice or currently under investigation in clinical trials.

Primary tumors from mucosal barrier organs drive unique eosinophil infiltration patterns and clinical associations

Eosinophils are bone marrow-derived granulocytes that display key effector functions in allergic diseases. Nonetheless, recent data highlight important roles for eosinophils in the tumor microenvironment (TME). Eosinophils have been attributed with pleiotropic and perhaps conflicting functions, which may be attributed at least in part to variations in eosinophil quantitation in the TME. Thus, a reliable, quantitative, and robust method for the assessment of eosinophilic infiltration in the TME is required. This type of methodology could standardize the identification of these cells and promote the subsequent generation of hypothesis-driven mechanistic studies. To this end, we conducted a comprehensive analysis of multiple primary tumors from distinct anatomical sites using a standardized method. Bioinformatics analysis of 10,469 genomically profiled primary tumors revealed that eosinophil abundance within different tumors can be categorized into three groups representing tumors with high, intermediate, and low eosinophil levels. Consequently, eosinophil abundance, as well as spatial distribution, was determined in tissue tumor arrays of six tumors representing all three classifications (colon and esophagus - high; lung - intermediate; cervix, ovary, and breast - low). With the exception of breast cancer, eosinophils were mainly localized in the tumor stroma. Importantly, the tumor anatomical site was identified as the primary predictive factor of eosinophil stromal density highlighting a distinction between mucosal-barrier organs versus non-mucosal barrier organs. These findings enhance our understanding of eosinophil diversity in the TME and provide a compelling rationale for future experiments assessing the activity of these cells.

Pathology of macrophage activation syndrome in humanized NSGS mice

"Humanized" immunodeficient mice generated via the transplantation of CD34+ human hematopoietic stem cells (hHSC) are an important preclinical model system. The triple transgenic NOD.Cg-Prkdc^scidIl2rg^tm1Wjl Tg(CMV-IL3,CSF2,KITLG)1Eav/MloySzJ (NSGS) mouse line is increasingly used as recipient for CD34+ hHSC engraftment. NSGS mice combine the features of the highly immunodeficient NSG mice with transgenic expression of the human myeloid stimulatory cytokines GM-CSF, IL-3, and Kit ligand. While generating humanized NSGS (huNSGS) mice from two independent cohorts, we encountered a fatal macrophage activation syndrome (MAS)-like phenotype resulting from the transplantation of CD34+ hHSC. huNSGS mice exhibiting this phenotype declined clinically starting at approximately 10 weeks following CD34+ hHSC engraftment, with all mice requiring euthanasia by 16 weeks. Gross changes comprised small, irregular liver, splenomegaly, cardiomegaly, and generalized pallor. Hematological abnormalities included severe thrombocytopenia and anemia. Pathologically, huNSGS spontaneously developed a disseminated histiocytosis with infiltrates of activated macrophages and hemophagocytosis predominantly affecting the liver, spleen, bone marrow, and pancreas. The infiltrates were chimeric with a mixture of human and mouse macrophages. Immunohistochemistry suggested activation of the inflammasome in both human and murine macrophages. Active Epstein-Barr virus infection was not a feature. Although the affected mice exhibited robust chimerism of the spleen and bone marrow, the phenotype often developed in the face of low chimerism of the peripheral blood. Given the high penetrance and early lethality associated with the MAS-like phenotype here described, we urge caution when considering the use of huNSGS mice for the development of long-term studies.

Biologics for the Treatment of Allergic Conditions: Eosinophil Disorders

Eosinophil-associated diseases are characterized by a common pathogenetic background, represented by eosinophil-led inflammation and overexpression of interleukin (IL)-5. IL-5 and its receptor are excellent therapeutic targets for eosinophil-associated diseases. Three monoclonal antibodies targeting IL-5 currently are available: mepolizumab and reslizumab block circulating IL-5 preventing the binding to its receptor, whereas benralizumab binds to IL-5 receptor α. They have a steroid-sparing effect in eosinophil disorders, such as eosinophilic granulomatosis with polyangiitis, hypereosinophilic syndrome, allergic bronchopulmonary aspergillosis, eosinophilic esophagitis, and chronic eosinophilic pneumonia. The biotechnological drugs targeting IL-5 are promising therapies; however, further studies are needed.

Association between eosinophilia and renal prognosis in patients with pathologically proven cholesterol crystal embolism

Background

Approximately, 20–70% of patients with cholesterol crystal embolism (CCE) have eosinophilia. However, it remains unknown how eosinophilia influences renal prognosis in patients with CCE. In this study, we investigated the association between eosinophil count (Eo) and renal prognosis in CCE patients on steroid therapy.

Methods

The present study is a single-centered retrospective cohort study in patients with renal dysfunction and CCE from April 2007 to May 2018. This study included the patients who were treated with neither maintenance dialysis nor steroid before CCE diagnosis, and followed-up for kidney function until November 2019. We assessed whether eosinophilia at the time of CCE diagnosis was related to renal death after treating with steroid therapy.

Results

Thirty patients with pathologically diagnosed CCE were enrolled and followed-up for 11.0 (5.2–43.4) months. There were significant differences in the white blood cell count (p = 0.01), hemoglobin (p = 0.009), serum creatinine levels (p = 0.008), phosphate (p = 0.049), and Eo (p = 0.008) between the renal survival and renal death groups. Using the receiver operating characteristic curve analysis with Youden index, Eo of 810/µL showed 100% sensitivity and 69.6% specificity for detecting renal death (area under the curve: 0.839). Comparing the outcomes in patients having Eo ≥ and < 810/µL using the log-rank test, there is a significantly higher renal death rate in CCE patients with Eo ≥ 810/µL (p = 0.0016).

Conclusion

Higher eosinophilia was a prognostic risk factor for renal death in the patients with CCE.

Distinguishment of parasite-infected children from pediatric inpatients with both eosinophilia and effusion

Patients with both serous effusion and eosinophilia are rarely reported and geographically distributed; their early diagnosis is difficult.According to the ultimate diagnosis, patients (≤14 years) in West China Second hospital with serous effusion and eosinophilia were divided into two groups including a parasitic group and a non-parasitic group. Clinical data were collected and analyzed between the two groups. Subsequently, significant measurement indicators were evaluated by receiver operating characteristic (ROC) curve to explore the optimal cut-off points for the most appropriate sensitivity and specificity.A total of 884 patients were diagnosed with serous effusion and 61 of them displayed co-morbidity with eosinophilia during enrolled time. Among 61 patients, 34 patients had parasitic infection and 27 had non-parasitic diseases. There were statistical difference in effusion position, the levels of white blood cell count (WBC), eosinophil (EOS), EOS%, C-reactive protein (CRP) between parasitic group and non-parasitic group. ROC curve demonstrated that the areas under the curve of EOS count and EOS% were >80%, and the corresponding optimal cut-off values were 1.71 × 10/L and 25.6% for distinguishing between parasitic and non-parasitic infections in our patients.This study provided a quantified index for potentially quick and convenient indicators of pediatric patients presenting with both eosinophilia and effusion. Eosinophils were helpful to improve the initial diagnosis with awareness of parasitic diseases. For the cases with EOS > 1.71 × 10/L or EOS% > 25.6%, parasitic infection should be considered and serological tests are recommended in our region.

Sympathetic Nerves Positively Regulate Eosinophil-Driven Allergic Conjunctivitis via α1-Adrenergic Receptor Signaling

Eosinophils are a major cause of tissue injury in allergic conjunctivitis. The biological nature of eosinophils in the conjunctiva and the mechanisms that control eosinophils' responses in allergic conjunctivitis are currently not completely understood. This study reports that conjunctival eosinophils comprise two populations-Siglec-F^int and Siglec-F^hi-in different life stages. Siglec-F^int eosinophils partly expressed CD34 and were in the immature (or steady) state. Siglec-F^hi eosinophils did not express CD34, sharply increased in number after short ragweed (SRW) pollen challenge, and were in the mature (or activated) state. Moreover, chemical sympathectomy by 6-hydroxydopamine reduced the recruitment and activation of eosinophils, whereas the activation of the sympathetic nerve system (SNS) with restraint stress accelerated the recruitment and activation of eosinophils in SRW-induced conjunctivitis. It was also found that two eosinophil populations expressed alpha-1a-adrenergic receptors (α1a-ARs); in SRW-induced conjunctivitis, treatment with an α1a-AR antagonist decreased eosinophil responses, whereas treatment with an α1a-AR agonist aggravated eosinophil responses. Thus, eosinophil responses in conjunctivitis are regulated by the SNS via α1a-AR signaling. SNS inputs or α1a-AR function may be potential targets for the treatment of allergic conjunctivitis.

Gastrointestinal Manifestations of Hypereosinophilic Syndromes and Mast Cell Disorders: a Comprehensive Review

Hypereosinophilic syndrome and mastocytosis are relatively rare proliferative diseases encountered in the general population. However, allergists frequently consider these disorders in the differential of patients presenting with gastrointestinal, pulmonary, cutaneous, and allergic symptoms. Gastrointestinal symptoms are some of the most frequent and/or debilitating aspects of both disease states and in many cases lead to poor quality of life and functional limitation for the patient. They are the third most common clinical manifestation in hypereosinophilic syndrome and have been found to be the most distressful aspect of the disorder in those with systemic mastocytosis. Both eosinophils and mast cells play integral parts in normal gut physiology, but when and how exactly their effector functionality translates into clinically significant disease remains unclear, and the available literature regarding their pathophysiology remains sparse. Eosinophils and mast cells even, in fact, may not necessarily function in isolation from each other but can participate in bidirectional crosstalk. Both are affected by similar mediators and can also influence one another in a paracrine fashion. Their interactions include both production of soluble mediators for specific eosinophil and mast cell receptors (for example, eosinophil recruitment and activation by mast cells releasing histamine and eotaxin) as well as direct physical contact. The mechanistic relationship between clonal forms of hypereosinophilia and systemic mastocytosis has also been explored. The nature of gastrointestinal symptomatology in the setting of both hypereosinophilic syndrome and mast cell disease is frequently manifold, heterogeneous, and the lack of better targeted therapy makes diagnosis and management challenging, especially when faced with a substantial differential. Currently, the management of these gastrointestinal symptoms relies on the treatment of the overall disease process. In hypereosinophilia patients, systemic corticosteroids are mainstay, although steroid-sparing agents such as hydroxyurea, IFN-α, methotrexate, cyclosporine, imatinib, and mepolizumab have been utilized with varying success. In mastocytosis patients, anti-mediator therapy with antihistamines and mast cell stabilization with cromolyn sodium can be considered treatments of choice, followed by other therapies yet to be thoroughly studied, including the role of the low-histamine diet, corticosteroids, and treatment of associated IBS symptoms. Given that both eosinophils and mast cells may have joint pathophysiologic roles, they have the potential to be a combined target for therapeutic intervention in disease states exhibiting eosinophil or mast cell involvement.

A systems biology approach for defining the potential molecular framework of idiopathic hypereosinophilic syndrome with cutaneous involvement

Hypereosinophilic syndrome (HES) is a rare multisystem disease that predominantly includes skin with severe and persistent itching. A lack of understanding about the pathological condition and mechanism of dermatosis caused by HES hinders its treatment. In the present study, we applied a quantitative proteomics approach to characterize the cellular responses of skin tissue to idiopathic HES (IHES) at the proteome level. We identified hundreds of skin tissue proteins that were differentially expressed between IHES patients and healthy individuals. IHES patients display severely damaged microenvironment, including extracellular matrix (ECM) organization and disassembly, immune disorders, decreased metabolic capacity, and susceptibility to microbial infection. Moreover, there was abnormal proliferation of basal epidermal stem cells, which was closely related to high expression of the epigenetic regulator, histone deacetylase 2, providing mechanistic insight into the abnormal epidermal thickening of IHES skin tissues. Overall, our study provides a comprehensive framework for a system-level understanding of IHES-induced dermatosis (IHESiD) tissues at the protein and cell pathway levels. Our findings may facilitate a new approach to diagnosis and treatment to alleviate skin clinical symptoms, monitor the activity of IHES, and determine therapeutic effects.

Acute kidney injury secondary to thrombotic microangiopathy associated with idiopathic hypereosinophilic syndrome: a case report and review of the literature

Background

Renal involvement in idiopathic hypereosinophilic syndrome is uncommon. The mechanism of kidney damage can be explained as occurring via two distinct pathways: (1) thromboembolic ischemic changes secondary to endocardial disruption mediated by eosinophilic cytotoxicity to the myocardium and (2) direct eosinophilic cytotoxic effect to the kidney.

Case presentation

We present a case of a 63-year-old Caucasian man who presented to our hospital with 2 weeks of progressively generalized weakness. He was diagnosed with idiopathic hypereosinophilic syndrome with multiorgan involvement and acute kidney injury with biopsy-proven thrombotic microangiopathy. Full remission was achieved after 8 weeks of corticosteroid therapy.

Conclusion

Further studies are needed to investigate if age and absence of frank thrombocytopenia can serve as a prognostic feature of idiopathic hypereosinophilic syndrome, as seen in this case.

Gallbladder cancer accompanied by uncontrollable eosinophilia: report of a case

A 48-year-old male was referred to our hospital for evaluation of motor speech disorders and difficulty in the movement of both the hands. The clinical diagnosis was Trousseau's syndrome due to advanced gallbladder cancer (cT3aN1M0). The patient received anticoagulation therapy and systemic chemotherapy (gemcitabine and cisplatin). Motor speech disorders and difficulty in movement of both hands were recovered. After 2 courses of chemotherapy, the primary tumor developed a massive hepatic invasion and the peripheral blood eosinophils increased gradually. The patient was admitted to our hospital for abdominal distension, fever, right upper quadrant pain, systemic edema, loss of appetite, and general malaise. The peripheral blood eosinophil count was markedly elevated to 45,900/μl (90.3%). The serum level of GM-CSF was high and there was no evidence of leukemia, allergic status and other diseases. The patient was diagnosed as paraneoplastic eosinophilia with advanced gallbladder cancer, which was suspected to produce GM-CSF. The patient received palliative support and died of disseminated intravascular coagulation 15 days after admission. We herein reported a fatal case of gallbladder cancer suspected of producing GM-CSF.

Eosinophils in the gastrointestinal tract and their role in the pathogenesis of major colorectal disorders

Eosinophils are currently regarded as versatile mobile cells controlling and regulating multiple biological pathways and responses in health and disease. These cells store in their specific granules numerous biologically active substances (cytotoxic cationic proteins, cytokines, growth factors, chemokines, enzymes) ready for rapid release. The human gut is the main destination of eosinophils that are produced and matured in the bone marrow and then transferred to target tissues through the circulation. In health the most important functions of gut-residing eosinophils comprise their participation in the maintenance of the protective mucosal barrier and interactions with other immune cells in providing immunity to microbiota of the gut lumen. Eosinophils are closely involved in the development of inflammatory bowel disease (IBD), when their cytotoxic granule proteins cause damage to host tissues. However, their roles in Crohn’s disease and ulcerative colitis appear to follow different immune response patterns. Eosinophils in IBD are especially important in altering the structure and protective functions of the mucosal barrier and modulating massive neutrophil influx to the lamina propria followed by transepithelial migration to colorectal mucus. IBD-associated inflammatory process involving eosinophils then appears to expand to the mucus overlaying the internal gut surface. The author hypothesises that immune responses within colorectal mucus as well as ETosis exerted by both neutrophils and eosinophils on the both sides of the colonic epithelial barrier act as additional pathogenetic factors in IBD. Literature analysis also shows an association between elevated eosinophil levels and better colorectal cancer (CRC) prognosis, but mechanisms behind this effect remain to be elucidated. In conclusion, the author emphasises the importance of investigating colorectal mucus in IBD and CRC patients as a previously unexplored milieu of disease-related inflammatory responses.

Colonic hypereosinophilia in ulcerative colitis may help to predict the failure of steroid therapy

BACKGROUND

Although glucocorticosteroids (GS) and mesalazine are effective and widely employed to treat moderate-to-severe ulcerative colitis (UC), information regarding the factors responsible for response to such therapy is still scarce. One of these factors is thought to be an increased number of mucosal eosinophils. The aim of our study was to determine whether the presence of hypereosinophilia in colonic mucosa of UC patients might influence the short-term response to l treatment with GS and mesasalazine.

METHODS

Clinical, endoscopic, and pathologic data from patients with a recent diagnosis of moderate UC, who had not undergone treatment, were obtained, and the short-term outcome after 1 month of conventional first-line treatment (mesalazine plus GS) was evaluated.

RESULTS

There were 53 patients with a median age of 37 years (95% CI 30-47).Overall, at the end of treatment period 16 (30%) patients responded, whereas a response was not observed in the other 37 (70%) patients. Interestingly, all patients of this latter group had colonic mucosal hypereosinophilia. No significant differences were found between the two groups concerning sex and age at diagnosis, but hypereosinophilia was inversely correlated with the duration of the disease (p = 0.054), and significantly correlated to the localization of UC (p = 0.0023). In addition, The Mayo score was significantly higher in patients with hypereosinophilia (median 8; 95% CI 8-9;) when compared to patients without hypereosinophilia (median 7; 95% CI 7-7, p < 0.0001) including the Mayo endoscopic subscore (median 3; 95% CI 2-3 vs median 2; 95% CI 2-2, respectively; p = 0.007).

CONCLUSIONS

The presence of colonic mucosal hypereosinophilia may be useful to predict the short-term outcome to conventional first-line therapy in treatment-naïve UC patients. It remains to be seen whether this might be important in modifying the first-line therapy in this subgroup of patients.

Parasitic Hypereosinophilia in Childhood: a Diagnostic Challenge

Severe hypereosinophilia (HE) in children is rare, and its etiological diagnosis is challenging. We describe a case of a 30-month-old boy, living in a rural area, who was admitted to our Clinic with a 7-day history of fever and severe hypereosinophilia. A comprehensive diagnostic workup could not identify the cause of this condition. On day 6, the rapidly increasing eosinophil count (maximum value of 56,000/mm3), the risk of developing hypereosinophilic syndrome, and the patient's history prompted us to undertake an empiric treatment with albendazole. The eosinophil count progressively decreased following treatment. On day 13, clinical condition and hematological data were satisfactory, therefore the treatment was discontinued, and the patient was discharged. Three months later, anti-nematode IgG antibodies were detected in patient serum, thus establishing the etiological diagnosis. In conclusion, an empiric anthelmintic treatment seems to be justified when parasitic hypereosinophilia is strongly suspected, and other causes have been excluded.

Innate immunity as the orchestrator of allergic airway inflammation and resolution in asthma

The respiratory system is constantly in direct contact with the environment and, has therefore, developed strong innate and adaptive immune responses to combat pathogens. Unlike adaptive immunity which is mounted later in the course of the immune response and is naive at the outset, innate immunity provides the first line of defense against microbial agents, while also promoting resolution of inflammation. In the airways, innate immune effector cells mainly consist of eosinophils, neutrophils, mast cells, basophils, macrophages/monocytes, dendritic cells and innate lymphoid cells, which attack pathogens directly or indirectly through the release of inflammatory cytokines and antimicrobial peptides, and coordinate T and B cell-mediated adaptive immunity. Airway epithelial cells are also critically involved in shaping both the innate and adaptive arms of the immune response. Chronic allergic airway inflammation and linked asthmatic disease is often considered a result of aberrant activation of type 2 T helper cells (Th2) towards innocuous environmental allergens; however, innate immune cells are increasingly recognized as key players responsible for the initiation and the perpetuation of allergic responses. Moreover, innate cells participate in immune response regulation through the release of anti-inflammatory mediators, and guide tissue repair and the maintenance of airway homeostasis. The scope of this review is to outline existing knowledge on innate immune responses involved in allergic airway inflammation, highlight current gaps in our understanding of the underlying molecular and cellular mechanisms and discuss the potential use of innate effector cells in new therapeutic avenues.

Thymoquinone inhibits inflammation, neoangiogenesis and vascular remodeling in asthma mice

Asthma is a chronic obstructive disease which is characterized by recurring airway inflammation, reversible airway obstruction, airway hyper responsiveness and vascular remodeling. Thymoquinone (TQ), an active ingredient isolated from Nigella sativa, was reported to exhibit anti-inflammation and anti-proliferation of in various cancer cells as well as epithelial cells. The aim of this study was to evaluate the effect of TQ on the inflammation, neoangiogenesis and vascular remodeling induced by Ovalbumin (OVA) in asthma mice in vivo and the anti-angiogenesis effects of TQ in VEGF-induced human umbilical vein endothelial cells (HUVECs) in vitro. Our results revealed that TQ inhibited the production of inflammatory factors interleukin-4/-5 (IL-4/-5) by enzyme-linked immunesorbent assay (ELISA). Immunohistochemistry analysis showed that the increase of platelet endothelial cell adhesion molecule-1, which is also known as CD31 and α-smooth muscle actinalpha (α-SMA) expression in asthma mice challenged by OVA was suppressed by TQ. Moreover, TQ suppressed the activation of VEGFR2-PI3K-Akt pathway and up-regulated the expression of Slit glycoprotein-2 (Slit-2) both in vivo and in vitro with the inhibition of tube information in HUVEC cells. Meanwhile immunofluorescence analysis showed that Slit-2 and Roundabout-4 (Robo-4) were co-expressing after TQ treatment in OVA-challenged asthma mice. Our study demonstrates that TQ attenuated the inflammatory reaction by antagonizing IL-4/-5 while the anti-neoangiogenesis effect of TQ is mediated by inhibition of vascular endothelial growth factor (VEGF) expression through VEGFR2/PI3K/Akt signaling pathway, which supports a potential role for TQ in ameliorating asthma.

Novel Therapies for Eosinophilic Disorders

Current therapies for eosinophilic disorders are limited. Most treatment approaches remain empirical, are not supported by data from controlled clinical trials, involve the off-label use of agents developed for treatment of other diseases, and tend to rely heavily on the use of glucocorticoids and other agents with significant toxicity. Great progress has been made in the discovery, preclinical development, and clinical testing of a variety of biologics and small molecules that have the potential to directly or indirectly influence eosinophils, eosinophilic inflammation, and the consequences of eosinophil activation.

Eosinophils in mucosal immune responses

Eosinophils, multifunctional cells that contribute to both innate and adaptive immunity, are involved in the initiation, propagation, and resolution of immune responses, including tissue repair. They achieve this multifunctionality by expression of a diverse set of activation receptors, including those that directly recognize pathogens and opsonized targets, and by their ability to store and release preformed cytotoxic mediators that participate in host defense, to produce a variety of de novo pleotropic mediators and cytokines, and to interact directly and indirectly with diverse cell types, including adaptive and innate immunocytes and structural cells. Herein, we review the basic biology of eosinophils and then focus on new emerging concepts about their role in mucosal immune homeostasis, particularly maintenance of intestinal IgA. We review emerging data about their development and regulation and describe new concepts concerning mucosal eosinophilic diseases. We describe recently developed therapeutic strategies to modify eosinophil levels and function and provide collective insight about the beneficial and detrimental functions of these enigmatic cells.

Management of hypereosinophilia in tropical settings

Hypereosinophilia includes a group of commonly encountered clinical situations with symptoms ranging from mild and clinically innocuous to devastating presentations with high morbidity and mortality. The presentations and complications can be easily missed if the clinician is unaware of the diverse entities responsible for hypereosinophilia. The hypereosinophilic syndromes encompass entities that are associated with varying degrees of organ dysfunction either directly due to eosinophilic infiltration or as a result of substances secreted by the eosinophils. These conditions may be neoplastic or reactive in aetiology and a diligent search for secondary causes is essential. Evaluation and management algorithms in the tropical setting and in developing countries may differ from elsewhere. A review of hypereosinophilia and hypereosinophilic syndromes is presented with a diagnostic and therapeutic decision making algorithm modified for use in the tropical setting.