Gene therapy in a murine model of chronic eosinophilic leukemia-not otherwise specified (CEL-NOS).

Chronic eosinophilic leukemia-not otherwise specified (CEL-NOS) is a rare, aggressive, fatal disease characterized by blood eosinophilia and dysfunction of organs infiltrated with eosinophils. Clinically, the disease manifests with weight loss, cough, weakness, diarrhea, and multi-organ dysfunction that is unresponsive to therapy. We developed a one-time gene therapy for CEL-NOS using an adeno-associated virus (AAV) expressing an anti-eosinophil monoclonal antibody (AAVrh.10mAnti-Eos) to provide sustained suppression of eosinophil numbers in blood, thus reducing eosinophil tissue invasion and organ dysfunction. A novel CEL-NOS model was developed in NOD-scid IL2rγnull (NSG) mice by administration of AAV expressing the cytokine IL5 (AAVrh.10mIL5), resulting in marked peripheral and tissue eosinophilia of the heart, lung, liver, and spleen, and eventually death. Mice were administered AAVrh.10mAnti-Eos (1011 genome copies) 4 wk after administration of AAVrh.10mIL5 and evaluated for anti-eosinophil antibody expression, blood eosinophil counts, organ eosinophil invasion, and survival. AAVrh.10mAnti-Eos expressed persistent levels of the anti-eosinophil antibody for >24 wk. Strikingly, CEL-NOS treated mice had markedly lower blood eosinophil levels and reduced mortality when compared with control treated mice. These results suggest that a single treatment with AAVrh.10mAnti-Eos has the potential to provide substantial therapeutic benefit to patients with CEL-NOS, a fatal malignant disorder.

Treatment of lymphocyte-variant hypereosinophilic syndrome (L-HES): what to consider after confirming the elusive diagnosis.

Lymphocyte-variant hypereosinophilic syndrome (L-HES) is a rare disease driven by immunophenotypically aberrant T cells producing eosinophilopoetic cytokines such as interleukin-5 (IL-5). Treatment is challenging because L-HES is relatively steroid resistant and not amenable to tyrosine kinase inhibitors. We searched the literature for clinical trials and observational studies, including case reports, of patients treated for L-HES. In all, 25 studies were selected; two were randomised controlled trials of IL-5 blockade, which included some patients with L-HES, and the rest were observational studies. Corticosteroids are often used as first-line therapy, but patients with L-HES have lower response rates than other types of HES. Treatments that reduce symptoms and steroid dependence in some patients include interferon-alpha (IFN-α), anti-IL-5 monoclonal antibodies, cyclosporine and mycophenolate. These drugs target T-cell activation and proliferation, or IL-5 directly. Although effective, IFN-α and cyclosporine were commonly reported to cause side-effects resulting in discontinuation. Alemtuzumab can induce remissions, but these are generally short lived. The anti-IL-5 monoclonal antibodies mepolizumab and benralizumab are effective and well tolerated, but with a high rate of relapse once withdrawn. Hydroxyurea, methotrexate, imatinib were unsuccessful in most patients studied. More prospective clinical trials are needed for patients with L-HES.

Eosinophilia Associated With CD3-CD4+ T Cells: Characterization and Outcome of a Single-Center Cohort of 26 Patients.

Background: Lymphocytic variant hypereosinophilic syndrome is characterized by marked over-production of eosinophilopoietic factor(s) by dysregulated T cells leading to eosinophil expansion. In most cases, these T cells are clonal and express a CD3-CD4+ phenotype. As this is a rare disorder, presenting manifestations, disease course, treatment responses, and outcome are not well-characterized. Materials and Methods: In this retrospective single-center observational study, we reviewed medical files of all patients with persistent hypereosinophilia seen between 1994 and 2019 in whom CD3-CD4+ T cells were detected. Data collection included clinical and biological findings at presentation, treatment responses, disease course, and serial CD3-CD4+ T cell counts. Results: Our cohort comprises 26 patients, including 2 with hypereosinophilia of undetermined significance. All 24 symptomatic patients had cutaneous lesions and/or angioedema, and fasciitis was present in several cases. The aberrant T cell subset represented 2% or less total lymphocytes in 11 subjects. TCR gene rearrangement patterns on whole blood were polyclonal in these cases, while they all had serum CCL17/TARC levels above 1,500 pg/ml. Disease manifestations were mild and did not require maintenance therapy in roughly one third of the cohort, while two thirds required long-term oral corticosteroids and/or second-line agents. Among these, interferon-alpha was the most effective treatment option with a response observed in 8/8 patients, one of whom was cured of disease. Treatment had to be interrupted in most cases however due to poor tolerance and/or development of secondary resistance. Anti-interleukin-5 antibodies reduced blood eosinophilia in 5/5 patients, but clinical responses were disappointing. A sub-group of 5 patients had severe treatment-refractory disease, and experienced significant disease- and treatment-related morbidity and mortality, including progression to T cell lymphoma in three. Conclusions: This retrospective longitudinal analysis of the largest monocentric cohort of CD3-CD4+ T cell associated lymphocytic variant hypereosinophilic syndrome published so far provides clinicians confronted with this rare disorder with relevant new data on patient presentation and outcome that should help tailor therapy and follow-up to different levels of disease severity. It highlights the need for novel therapeutic options, especially for the subset of patients with severe treatment-refractory disease. Future research efforts should be made toward understanding CD3-CD4+ T cell biology in order to develop new treatments that target primary pathogenic mechanisms.

Two Immunocompromised Patients With Diffuse Alveolar Hemorrhage as a Complication of Severe Coronavirus Disease 2019.

Diffuse alveolar hemorrhage (DAH) is a severe and potentially life-threatening disease manifestation. In addition to autoimmune diseases such as antineutrophil cytoplasmic antibody-associated vasculitis and anti-glomerular basement membrane syndrome, pulmonary viral infections are known to be culprits of DAH. Health-care providers worldwide in the coronavirus disease 2019 pandemic have been confronted with an unprecedented number of viral lung infections, with great variance in symptoms and severity. Hemoptysis, the key symptom of DAH, is a rare complication. We present two cases of immunocompromised patients with rapidly developing hypoxemic respiratory failure and evidence of DAH in the context of severe acute respiratory syndrome coronavirus 2 infection.

Systemic hypereosinophilic syndromes: when autoimmunity is Th2 mediated.

PURPOSE OF REVIEW: Clinical conditions associated with hypereosinophilia represent a field of particular interest, taking into account the epidemiological impact of the different primary and secondary forms. In addition to a classical Th1 response, also Th2 cells can be involved in the pathogenesis of autoimmune diseases, among them eosinophilic forms such as eosinophilic granulomatosis with polyangiitis. RECENT FINDINGS: In patients with severe asthma, recent evidence highlights the role of pathogenic autoantibodies against autologous eosinophil proteins (e.g. eosinophil peroxidase) suggest the role of autoimmune mechanisms, particularly in patients in which asthma is included in eosinophilic vasculitis with antineutrophilic autoantibody positivity. Is now evident that in addition to Th2 cells, also type 2 innate lymphoid cells and Th1/Th17 cells play a central role in the pathogenesis of hypereosinophilic syndrome. SUMMARY: The definition of cellular and molecular mechanisms and the critical role of specific cytokines involved in the pathogenesis of hypereosinophilic syndrome open the way to new therapeutic strategies by using biological agents targeting these specific factors.

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.

Steroid Resistant Hypereosinophilic Syndrome Suspected to Be Caused by Aberrant T-cell Subset.

A 53-year-old male presented with cough, skin rash and lymphadenopathies complicated with hypereosinophilia (HE) in the blood, and patchy shadows in both lungs on chest computed tomography. Reactive causes for HE were excluded, and no clinical or laboratory features of myeloproliferative disorders could be found. HE caused by aberrant T-cell subsets was suspected because of serum hyper-immunoglobulin E level, and organ involvement of skin and lungs, though we could show neither aberrant T-cell surface markers nor T-cell receptor gene rearrangement. In the course of steroid monotherapy, tolerable maintenance dose could not be attained and the steroid-sparing agents of hydroxycarbamide, cyclosporine and interferon-α were introduced. However, the therapeutic response was inadequate, and organ involvement of lungs and intestinal tract developed. HE caused by aberrant T-cell subsets has steroid resistance and a risk of malignant transition, and we considered this progressive steroid refractoriness to be a sign of such a transition. Cytotoxic chemotherapy or bone marrow transplantation will likely be the next treatment modality in this patient.

Rare manifestation of hypereosinophilic syndrome: Diffuse-type hair loss with massive perifollicular eosinophils.

A 46-year-old woman consulted our hospital with diffuse alopecia and blood eosinophilia. Histological examination of the scalp revealed dense eosinophilic infiltration around the hair follicles and in the surrounding subcutis. Oral corticosteroid was effective to reduce hair loss and blood eosinophilia, but these conditions immediately relapsed after ending treatment. In addition to alopecia, she had diarrhea and colitis showing histological findings of dense eosinophilic infiltrations in the submucosa. We diagnosed hypereosinophilic syndrome based on hypereosinophilia of blood and tissue with clinical symptoms of alopecia and diarrhea. We suppose diffuse alopecia showing massive eosinophilic infiltration around the hair follicle is a rare symptom of hypereosinophilic syndrome.

Hypereosinophilic syndromes in the precision medicine era: clinical, molecular aspects and therapeutic approaches (targeted therapies).

Introduction: Hypereosinophilic syndromes are a heterogeneous group of disorders that may be associated with life-threatening organ injury as a result of tissues infiltration by eosinophils. The main goal of therapy is to mitigate eosinophil-mediated organ damage. When possible, therapy should be directed at the underlying etiology. However, even in the absence of any known cause, when organ damage is present, hypereosinophilia must be treated promptly and aggressively to reduce potential morbidity and mortality.Areas covered: Conventional therapies, including corticosteroids, hydroxyurea (hydroxycarbamide) and interferon-alpha, have shown variable efficacy and a non-negligible toxicity emphasizing the need of new therapeutic strategies based on drugs with different mechanisms of action.Expert opinion: Tyrosine kinase inhibitors have a central role among targeted therapies of hypereosinophilic syndromes. Imatinib, initially empirically used based on its activity in chronic myeloid leukemia, achieved preliminary excellent results further confirmed in large series of patients. Third-generation tyrosine kinase inhibitors such as ponatinib, while active in vitro and in vivo in animals, still deserve confirmation in properly designed clinical trials. In addition, clinical investigation on monoclonal antibodies against interleukin-5, interleukin-5Rα, IgE, and CD52 represents a promising area of research.

Mechanisms of glucocorticoid resistance in hypereosinophilic syndromes.

BACKGROUND: Glucocorticoids (GC) are considered first-line therapy for most patients with hypereosinophilic syndrome (HES). Although response rates are generally high, many patients require moderate to high doses for control of eosinophilia and symptoms, and up to 15% of patients do not respond at all. Despite this, little is known about the mechanisms of GC resistance in patients with HES. OBJECTIVE: To explore the aetiology of GC resistance in HES. METHODS: Clinical data and samples from 26 patients with HES enrolled on a prospective study of GC responsiveness and 23 patients with HES enrolled on a natural history study of eosinophilia for whom response to GC was known were analysed retrospectively. Expression of GC receptor isoforms was assessed by quantitative RT-PCR in purified eosinophils. Serum cytokine levels were quantified by suspension array assay in multiplex. RESULTS: Despite an impaired eosinophil response to GC after 7 days of treatment, the expected rise in absolute neutrophil count was seen in 7/7 GC-resistant patients, suggesting that GC resistance in HES is not a global phenomenon. Eosinophil mRNA expression of glucocorticoid receptor (GR) isoforms (α, ß, and P) was similar between GC-sensitive (n = 20) and GC-resistant (n = 9) patients with HES. Whereas geometric mean serum levels were also comparable between GC-r (n = 11) and GC-s (n = 19) for all cytokines tested, serum IL-5 levels were >100 pg/mL only in GC-r patients. CONCLUSIONS AND CLINICAL RELEVANCE: These data suggest that the mechanism of GC resistance in HES is not due to a global phenomenon affecting all lineages, but may be due, at least in some patients, to impairment of eosinophil apoptosis by increased levels of IL-5.

Characterization of a mouse model of hypereosinophilia-associated heart disease.

Hypereosinophilic syndrome is characterized by sustained and marked eosinophilia leading to tissue damage and organ dysfunction. Morbidity and mortality occur primarily due to cardiac and thromboembolic complications. Understanding the cause and mechanism of disease would aid in the development of targeted therapies with greater efficacy and fewer side effects. We discovered a spontaneous mouse mutant in our colony with a hypereosinophilic phenotype. Mice develop peripheral blood eosinophilia; infiltration of lungs, spleen, and heart by eosinophils; and extensive myocardial damage and remodeling. This ultimately leads to heart failure and premature death. Histopathological assessment of the hearts revealed a robust inflammatory infiltrate composed primarily of eosinophils and B-lymphocytes, associated with myocardial damage and replacement fibrosis, consistent with eosinophilic myocarditis. In many cases, hearts showed dilatation and thinning of the right ventricular wall, suggestive of an inflammatory dilated cardiomyopathy. Most mice showed atrial thrombi, which often filled the chamber. Protein expression analysis revealed overexpression of chemokines and cytokines involved in innate and adaptive immunity including IL-4, eotaxin, and RANTES. Disease could be transferred to wild-type mice by adoptive transfer of splenocytes from affected mice, suggesting a role for the immune system. In summary, the pathologies observed in the mutant lines are reminiscent of those seen in patients with hypereosinophilia, where cardiac-related morbidities, like congestive heart failure and thrombi, are the most common causes of death. As such, our model provides an opportunity to test mechanistic hypotheses and develop targeted therapies.NEW & NOTEWORTHY This article describes a new model of heart disease in hypereosinophilia. The model developed as a spontaneous mouse mutant in the colony and is characterized by peripheral blood eosinophilia and infiltration of lungs, spleen, and heart by eosinophils. In the heart, there is extensive myocardial damage, remodeling, fibrosis, and thrombosis, leading to heart failure and death. The immune microenvironment is one of increased innate and adaptive immunity, including Th1 and Th2 cytokines/chemokines. Finally, adoptive transfer of splenocytes transfers disease to recipient mice. In summary, this model provides an opportunity to test mechanistic hypotheses and develop targeted therapies for this rare but devastating disease.

Pemphigus-like hypereosinophilic syndrome with FIP1L1-PDGFRA fusion gene: A challenging and uncommon clinical presentation.

Hypereosinophilic syndrome (HES) is often associated with cutaneous manifestations, mostly pruritic lesions, urticaria and angioedema. Mucosal lesions are rarely seen in HES but, when present, are usually the first manifestation of the disease. The clinical presentation may be heterogeneous, including erosions, aphthae or ulcers, and can be easily confused with other mucocutaneous disorders. Here, we present the case of a 64-year-old man with severe chronic erosive oral mucositis simulating pemphigus in which the finding of persistent eosinophilia and elevation of B12 vitamin serum levels raised the suspicion of HES. The FIP1L1-PDGFRA fusion gene (4q12) was detected by fluorescence in situ hybridization and the patient was treated with imatinib mesylate with complete response of the disease.

[Hypereosinophilic syndromes]. / Syndromes hyperéosinophiliques.

Hypereosinophilic syndromes. Hypereosinophilic syndromes (HES) is a protean condition defined by chronic blood eosinophilia ≥ 1.5 G/L (> 1 month) leading to eosinophilic-related organ damage. HES subtypes includes neoplastic (clonal) disorders (HESN, that comprises FIP1L1-PDGFRA- related chronic eosinophilic leukemia and myeloproliferative and myelodysplastic syndromes associated with eosinophilia) and reactive HES (HESR, that aggregates all conditions e.g. parasitic infections, adverse drug reactions, inflammatory or neoplastic diseases that lead to the production of Th2-related cytokines and thereby to non-clonal hypereosinophilia). HESR also includes the lymphoid variant of HES (HESL), a chronic clonal indolent T-cell lymphoproliferative disorder in which mature peripheral T cells secrete high amounts of IL-5, leading to the polyclonal expansion of eosinophils. Despite an extensive etiological workup, approximately 50% of HES remain of undetermined cause. HES-related clinical manifestations are highly diverse, but dermatological, respiratory and gastro-intestinal symptoms are the most frequent. The long-term prognosis is driven by cardiac involvement and, for patients with HESN and HESL, by the risk of acute transformation into high-grade hematological malignancies. Treatment of HESN relies on tyrosine kinase inhibitors (e.g. imatinib mesylate), while oral glucocorticoids are the usual the fist-line therapy for HESR (including SHEL). In this setting, second-line treatments include hydroxyurea and Peg-interferon alfa-2a. IL-5-targeted therapies are very promising (except for HESN). Yet, to date, their use is restricted to clinical trials and to a compassionate use program dedicated to severe and refractory patients.

Syndromes hyperéosinophiliques. Les syndromes hyperéosinophiliques sont définis par l'association d'une hyperéosinophilie sanguine supérieure ou égale à 1,5 G/L d'évolution chronique (> 1 mois) à des dommages tissulaires (quels qu'ils soient) en rapport avec l'infiltration éosinophilique. Il s'agit d'une entité hétérogène qui comprend notamment les syndromes hyperéosinophiliques néoplasiques « clonaux ¼ (SHEN) [dont la leucémie chronique à éosinophiles liée à la délétion FIP1L1-PDGFRA et les éosinophilies associées aux autres syndromes myéloprolifératifs et myélodysplasiques] et les syndromes hyperéosinophiliques réactionnels (SHER, entité hétérogène regroupant l'ensemble des situations (infections parasitaires, prise médicamenteuse, maladies inflammatoires ou néoplasiques) responsables de la production de cytokines Th2 conduisant à une hyperéosinophilie non clonale. Parmi les SHER, on distingue les SHE lymphoïdes (SHEL), où la production d'interleukine 5 (IL-5) est liée à la présence d'une lymphoprolifération T de bas grade de phénotype aberrant (généralement CD3-CD4+). Malgré un bilan causal exhaustif large, on estime qu'environ 50 % des SHE restent d'origine indéterminée. Les manifestations cliniques sont diverses et les atteintes dermatologiques, respiratoires et digestives sont les plus fréquentes. Le pronostic à long terme est surtout corrélé à l'atteinte cardiaque et, pour les SHEN et les SHEL, au risque d'acutisation en pathologie maligne de haut grade (leucémie aiguë myéloblastique et lymphome T périphérique respectivement). La prise en charge des SHEN repose sur les inhibiteurs de tyrosine kinase, notamment l'imatinib mésylate. Pour les SHER (y compris les SHEL), la corticothérapie est généralement efficace, et les thérapeutiques de deuxième ligne sont l'hydroxyurée et le peginterféron alpha-2a. Les biothérapies ciblant l'IL-5 sont très prometteuses (hors SHEN) mais leur utilisation est pour l'instant limitée aux essais thérapeutiques et à un protocole d'usage compassionnel pour les patients les plus sévères et réfractaires aux thérapeutiques de première ligne.

Hypereosinophilic syndrome: approach to treatment in the era of precision medicine.

Hypereosinophilic syndromes (HESs) are a heterogeneous group of rare disorders characterized by peripheral eosinophilia and eosinophilic end organ complications. Conventional therapies, including glucocorticoids and cytotoxic and immunomodulatory agents, have variable efficacy and significant toxicity. Although the recent development of agents that target eosinophils, including tyrosine kinase inhibitors and monoclonal antibodies, provides the possibility of more effective, less toxic approaches to treatment of HES, there are little available data to guide their use in these conditions. In the following review, the controversies regarding the definition and classification of HES will be discussed, and a pragmatic approach to treatment based on clinically defined HES variants will be presented. An illustrative case will be used to highlight the complexities of treatment selection in HES patients.

An Approach to the Evaluation of Persistent Hypereosinophilia in Pediatric Patients.

Hypereosinophilia (HE) is currently defined by a peripheral blood absolute eosinophil count (AEC) of ≥1,500 cells/microL. Although mild blood eosinophilia (AEC 500-1,500 cells/microL) is observed relatively frequently within the pediatric population, persistent HE is uncommon and should prompt additional clinical evaluation. While the clinical manifestations and underlying etiologies of HE in adults have been well-characterized, there is a paucity of data on HE in children. Limited evidence suggests that many similarities between adult and pediatric HE likely exist, but some important differences remain between these populations. The evaluation of HE in children can be challenging given the broad differential diagnosis, which includes primary hematologic disorders and secondary eosinophilia in which the increased eosinophil levels are propagated by disease states that promote eosinophil production and survival. On the basis of the underlying etiology, clinical manifestations can range from benign, self-resolving elevations in the AEC to life-threatening disorders with the potential for significant end-organ damage. Given the broad differential diagnosis of HE, it remains essential to systematically approach the evaluation of unexplained HE in children. This review will discuss the differential diagnosis for pediatric HE, highlighting etiologies that are more prevalent within the pediatric population. Additionally, a summary of the epidemiology of pediatric HE will be presented, with focus on some of the differences that exist between pediatric and adult HE. Finally, a directed approach to the diagnostic evaluation of children with HE will be discussed.