Novel approaches to therapy of hypereosinophilic syndromes

In-Depth Review of Loeffler Endocarditis: What Have We Learned?

Loeffler endocarditis, eosinophilic endocarditis or eosinophilic endomyocardial disease are conditions associated with hypereosinophilia and they affect the heart function. Loeffler endocarditis is a rare endomyocardial disorder thought to be caused by eosinophilic damage. The disorder is characterized by inflammatory infiltration, formation of thrombus within cardiovascular system, and ultimately fibrosis of the afflicted area. It can lead to multiple severe complications, including thromboembolic disease, thickening of fibrous tissue in the endocardium of ventricles, valve involvement, apical obliteration, and various heart disorders. Although early clinical intervention can lead to remission, the underlying mechanisms of the disorder remain unresolved. In the present article, we summarise the existing literature concerning Loeffler endocarditis based on PubMed, Web of Science, and other medical databases to conduct an in-depth review of the epidemiology, etiology, pathophysiological mechanisms, staging, diagnosis, treatment and prognosis of Loeffler endocarditis. Meanwhile, we provide novel patients data and clinical figures of Loeffler endocarditis to supplement the understanding of this cardiac disorder. The findings presented in this article provide a basis for further studies and can be used to improve management of the disorder.

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.

Loeffler's Endocarditis and Hypereosinophilic Syndrome

Loeffler's endocarditis and hypereosinophilic syndromes are a unique group of infiltrative disorders characterized by hypereosinophilia, inflammatory thrombotic, and ultimately, fibrotic involvement of the heart leading to multiple complications including valve involvement, thromboembolic phenomena, heart failure. Clinical recognition, comprehensive laboratory and multimodality imaging diagnostic workup, and early initiation of treatment have been shown to slow down the progression and promote remission. This review addresses a detailed analysis of Loeffler's endocarditis and hypereosinophilic syndromes.

Inflammatory profile in X-linked adrenoleukodystrophy patients: Understanding disease progression

X-linked adrenoleukodystrophy (X-ALD) is an inherited disease characterized by progressive inflammatory demyelization in the brain, adrenal insufficiency, and an abnormal accumulation of very long chain fatty acids (VLCFA) in tissue and body fluids. Considering that inflammation might be involved in pathophysiology of X-ALD, we aimed to investigate pro- and anti-inflammatory cytokines in plasma from three different male phenotypes (CCER, AMN, and asymptomatic individuals). Our results showed that asymptomatic patients presented increased levels of pro-inflammatory cytokines IL-1β, IL-2, IL-8, and TNF-α and the last one was also higher in AMN phenotype. Besides, asymptomatic patients presented higher levels of anti-inflammatory cytokines IL-4 and IL-10. AMN patients presented higher levels of IL-2, IL-5, and IL-4. We might hypothesize that inflammation in X-ALD is related to plasmatic VLCFA concentration, since there were positive correlations between C26:0 plasmatic levels and pro-inflammatory cytokines in asymptomatic and AMN patients and negative correlation between anti-inflammatory cytokine and C24:0/C22:0 ratio in AMN patients. The present work yields experimental evidence that there is an inflammatory imbalance associated Th1, (IL-2, IL-6, and IFN-γ), Th2 (IL-4 and IL-10), and macrophages response (TNF-α and IL-1β) in the periphery of asymptomatic and AMN patients, and there is correlation between VLCFA plasmatic levels and inflammatory mediators in X-ALD. Furthermore, we might also speculate that the increase of plasmatic cytokines in asymptomatic patients could be considered an early biomarker of brain damage and maybe also a predictor of disease progression.

Clinical overview of cutaneous features in hypereosinophilic syndrome

The hypereosinophilic syndromes (HES) are a heterogeneous group of disorders defined as persistent and marked blood eosinophilia of unknown origin with systemic organ involvement. HES is a potentially severe multisystem disease associated with considerable morbidity. Skin involvement and cutaneous findings frequently can be seen in those patients. Skin symptoms consist of angioedema; unusual urticarial lesions; and eczematous, therapy-resistant, pruriginous papules and nodules. They may be the only obvious clinical symptoms. Cutaneous features can give an important hint to the diagnosis of this rare and often severe illness. Based on advances in molecular and genetic diagnostic techniques and on increasing experience with characteristic clinical features and prognostic markers, therapy has changed radically. Current therapies include corticosteroids, hydroxyurea, interferon-α, the tyrosine kinase inhibitor imatinib mesylate, and (in progress) the monoclonal anti-interleukin-5 antibodies. This article provides an overview of current concepts of disease classification, different skin findings, and therapy for HES.

Pathogenesis and classification of eosinophil disorders: a review of recent developments in the field

Eosinophils and their products play an essential role in the pathogenesis of various reactive and neoplastic disorders. Depending on the underlying disease, molecular defect and involved cytokines, hypereosinophilia may develop and may lead to organ damage. In other patients, persistent eosinophilia is accompanied by typical clinical findings, but the causative role and impact of eosinophilia remain uncertain. For patients with eosinophil-mediated organ pathology, early therapeutic intervention with agents reducing eosinophil counts can be effective in limiting or preventing irreversible organ damage. Therefore, it is important to approach eosinophil disorders and related syndromes early by using established criteria, to perform all appropriate staging investigations, and to search for molecular targets of therapy. In this article, we review current concepts in the pathogenesis and evolution of eosinophilia and eosinophil-related organ damage in neoplastic and non-neoplastic conditions. In addition, we discuss classifications of eosinophil disorders and related syndromes as well as diagnostic algorithms and standard treatment for various eosinophil-related disorders.

Lung involvement in hypereosinophilic syndromes

BACKGROUND

Hypereosinophilic syndromes (HES) are a heterogeneous group of conditions that are characterized by tissue-associated eosinophilic inflammation and peripheral eosinophilia. Although clinical and radiologic features associated with most forms of eosinophilic lung diseases are relatively well-described, there is little known regarding lung involvement in HES. The aims of the present study were to ascertain the frequency of pulmonary involvement in HES and define associated clinical and radiologic features.

METHODS

We included all patients with HES seen over a 5-year period from 2004 to 2008 and examined their medical records and radiologic studies to obtain relevant data.

RESULTS

There were 49 patients (25 males and 24 females) with a median age of 50 years (range, 12-88 years); 18 (37%) had a history of tobacco use. In 12 patients (24%), these pulmonary manifestations were attributable to parenchymal lung involvement with HES. Radiologic manifestations of pulmonary involvement varied but most commonly consisted of patchy ground-glass opacities and consolidation; one patient exhibited numerous pulmonary nodules. Thirteen patients (27%) had asthma including 6 with a new diagnosis of this disorder. Initial treatment usually consisted of corticosteroids but additional therapeutic agents were employed during the clinical course and included hydroxyurea, interferon-α, imatinib, and mepolizumab. Most patients with pulmonary involvement with HES improved and no deaths were observed.

CONCLUSION

One-quarter of HES patients manifested pulmonary involvement with variable radiologic findings. Asthma was more common in HES than previously reported. Most patients with pulmonary involvement in HES improve with currently available therapies.

Current strategies in the management of hypereosinophilic syndrome, including mepolizumab

BACKGROUND

Patients with hypereosinophilic syndrome (HES) vary considerably in their clinical presentation with regard to the severity and pattern of end-organ involvement. Clinical manifestations range from nonspecific symptoms to life-threatening, multisystem damage caused by eosinophil infiltration and local release of proinflammatory mediators and toxic granule products from these invading cells. The primary objective of treatment is to reduce blood and tissue eosinophilia and prevent eosinophil-mediated tissue damage as safely as possible. Systemic corticosteroids, such as prednisone, are first-line therapy for the management of patients with symptomatic HES who lack the Fip1-like 1-platelet-derived growth factor receptor-alpha (FIP1L1-PDGFRA) gene fusion mutation. The tyrosine kinase inhibitor, imatinib, is first-line treatment for FIP1L1-PDGFRA-positive patients). Because of the toxicity and serious side-effects that can occur with oral corticosteroids, alternative therapies may need to be introduced to reduce the cumulative corticosteroid exposure while maintaining disease control.

SCOPE

Among corticosteroid-sparing agents are cytotoxic drugs and interferon-alpha; anti-interleukin-5 (IL-5) monoclonal antibodies are also currently under investigation for the treatment of HES. This manuscript reviews the available treatments for HES and the range of side-effects associated with long-term corticosteroid use, and then focuses on the anti-IL-5 monoclonal antibodies, mepolizumab and reslizumab. Of these, only mepolizumab has been studied in a randomized, placebo-controlled trial. Literature search methodology utilized www.pubmed.gov and www.clinicaltrials.gov with search terms including hypereosinophilic syndrome and corticosteroid side-effects coupled with search terms including eosinophils, mepolizumab and reslizumab through March 2010.

FINDINGS

Three case studies are presented that demonstrate the limitations of corticosteroid therapy in terms of tolerability and quality of life, and the subsequent use of mepolizumab as a corticosteroid-sparing agent in these individuals.

CONCLUSION

Targeted eosinophil-directed therapy with an anti-IL-5 neutralizing monoclonal antibody reduced the need for corticosteroids in these three HES patients without disease exacerbations.

[Synchronous detection of T-cell clonality and FIP1L1-PDGFRA fusion gene in a hypereosinophilic syndrome]

We report a 49-year-old man suffering from chronic hypereosinophilia whose biological tests revealed a gene rearrangement between FIP1L1 and PDGFRA as well as a T-cell clonality. After 1 year of therapy with imatinib mesylate (100 mg daily), the patient was clinically asymptomatic, the fusion transcript was undetectable using RTQ-PCR and no lymphoproliferative disorders occurred. This unique combination raises the question of the physiopathology of such a grey zone hypereosinophilia and their management.

Hypereosinophilic syndrome: a multicenter, retrospective analysis of clinical characteristics and response to therapy

BACKGROUND

Hypereosinophilic syndrome (HES) is a heterogeneous group of rare disorders defined by persistent blood eosinophilia > or =1.5 x 10(9)/L, absence of a secondary cause, and evidence of eosinophil-associated pathology. With the exception of a recent multicenter trial of mepolizumab (anti-IL-5 mAb), published therapeutic experience has been restricted to case reports and small case series.

OBJECTIVE

The purpose of the study was to collect and summarize baseline demographic, clinical, and laboratory characteristics in a large, diverse cohort of patients with HES and to review responses to treatment with conventional and novel therapies.

METHODS

Clinical and laboratory data from 188 patients with HES, seen between January 2001 and December 2006 at 11 institutions in the United States and Europe, were collected retrospectively by chart review.

RESULTS

Eighteen of 161 patients (11%) tested were Fip1-like 1-platelet-derived growth factor receptor alpha (FIP1L1-PDGFRA) mutation-positive, and 29 of 168 patients tested (17%) had a demonstrable aberrant or clonal T-cell population. Corticosteroid monotherapy induced complete or partial responses at 1 month in 85% (120/141) of patients with most remaining on maintenance doses (median, 10 mg prednisone equivalent daily for 2 months to 20 years). Hydroxyurea and IFN-alpha (used in 64 and 46 patients, respectively) were also effective, but their use was limited by toxicity. Imatinib (used in 68 patients) was more effective in patients with the FIP1L1-PDGFRA mutation (88%) than in those without (23%; P < .001).

CONCLUSION

This study, the largest clinical analysis of patients with HES to date, not only provides useful information for clinicians but also should stimulate prospective trials to optimize treatment of HES.

Advances in mechanisms of asthma, allergy, and immunology in 2008

This review summarizes selected articles appearing in 2008 in the Journal. Articles chosen include those improving our understanding of mechanisms of allergic diseases by focusing on human basophil, mast cell, and eosinophil biology; IgE and its high-affinity receptor on various cells; novel properties of omalizumab; airways remodeling; and genetics. Articles from other journals have been included to supplement the topics presented.

Advances in diagnosis and treatment of eosinophilia

PURPOSE OF REVIEW

Hypereosinophilic syndromes (HESs) are disorders characterized by sustained blood or tissue hypereosinophilia or both with subsequent damage to various organs due to eosinophilic infiltration and release of mediators. HES are now recognized to include varied eosinophilic disorders for some of which there are recent insights into their pathogenesis and targeted treatment.

RECENT FINDINGS

Studies have helped delineate two subtypes of HES: the myeloproliferative variants of HES and the lymphocytic variants of HES. Many, but not all, myeloproliferative-HES patients have interstitial deletions on chromosome 4q12 that lead to fusion of the FIP1-like 1 and platelet-derived growth factor receptor alpha genes, with the fusion product encoding a protein that has constitutive tyrosine kinase activity. Lymphocytic-HES is a primary lymphoid disorder characterized by nonmalignant expansion of a T-cell population able to produce eosinophilopoietic cytokines, with the T-cell population being identified by flow cytometry or reverse transcriptase-PCR for T-cell receptor usage or both. Other HES subtypes are of uncertain causes and are included in recent diagnostic algorithms for the spectrum of HES.

SUMMARY

The contemporary definition of the hypereosinophilic syndromes encompasses a range of eosinophilic disorders characterized by chronic blood hypereosinophilia often with eosinophil-mediated damage to various organs.