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

Abstract

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.

Impacts of eosinophil percentage on prognosis acute type A aortic dissection patients

“…Activated platelets, EETs, and MBP contribute to thrombus formation [ 25 , 26 ]. Eosinophils are pro-inflammatory cells and can release a great number of cytokines, growth factors, and chemokines, which enhance inflammatory reactions [ 22 , 27 , 28 ]. Cytokines, including interleukin (IL)-1β, IL-2, IL-6, IL-8, and tumor necrosis factor-α, are upregulated in AD patients [ 28 – 31 ], and may promote AD via apoptosis [ 32 , 33 ].…”

Solving the Conundrum of Eosinophils in Alloimmunity

“…Despite the historical categorization of eosinophils as destructive cells in asthma and parasite infection, eosinophils have nuanced and complex immune regulatory roles in health and disease. 4,28,29 Studies in mice have identified that at physiological homeostasis eosinophils maintain metabolic health 30 and aid in tissue remodeling during development. 31 They have also been shown to maintain a healthy microbiome in the gut 32 and promote vascular hemostasis.…”

Eosinophilic vasculitis as a manifestation of idiopathic hypereosinophilic syndrome

“…Dear Editor, Hypereosinophilic syndrome (HES) is characterized by peripheral eosinophilia (eosinophils, ≥1500/μL), eosinophil-associated end-organ damage, and no underlying causative disorders such as infections, allergic diseases, bullous diseases (e.g., bullous pemphigoid), pulmonary diseases, malignant neoplasms, and collagen diseases including eosinophilic granulomatosis with polyangiitis (EGPA). [1][2][3][4] We present the very rare case of a Japanese patient with eosinophilic vasculitis (EoV) as a cutaneous manifestation of idiopathic HES.…”

“…LETTER TO THE EDITOR Subtypes of HES include idiopathic, primary (or neoplastic), and secondary (or reactive) forms. [1][2][3] EoV as a manifestation of HES can be distinguished from primary systemic vasculitides such as EGPA. EGPA is a systemic eosinophilic, granulomatous ANCA-associated vasculitis affecting small-to medium-sized vessels in individuals with asthma (and/or allergic rhinitis), and peripheral eosinophilia.…”