Eosinophils: Old Players in a New Game

Abstract

Eosinophils are terminal polymorphonuclear cells with a high number of cytoplasmic granules that originate in bone marrow. Some are exosomes, which contain multiple molecules, such as specific eosinophilic proteins, cytokines, chemokines, enzymes, and lipid mediators that contribute to the effector role of these cells. Moreover, exosomes present a large number of receptors that allow them to interact with multiple cell types. Eosinophils play an important role in defense against infestations and are a key element in asthma and allergic diseases. Eosinophils are recruited to the inflamed area in response to stimuli, modulating the immune response through the release to the extracellular medium of their granule-derived content. Various mechanisms of degranulation have been identified. Polymorphonuclear leukocytes contain multivesicular bodies that generate exosomes that are secreted into the extracellular environment. Eosinophilic exosomes participate in multiple processes and mechanisms. Eosinophils participate actively in asthma and are hallmarks of the disease. The cells migrate to the inflammatory focus and contribute to epithelial damage and airway remodeling. Given their relevance in this pathology, new therapeutic tools have been developed that target mainly eosinophils and their receptors. In this manuscript, we provide a global, updated vision of the biology of eosinophils and the role of eosinophils in respiratory diseases, particularly asthma. We also summarize asthma treatments linked to eosinophils and new therapeutic strategies based on biological products in which eosinophils and their receptors are the main targets.

Benralizumab: A New Approach for the Treatment of Severe Eosinophilic Asthma

“…Eosinophils represent approximately 1%-5% of peripheral blood leukocytes. They are produced in bone marrow, and their differentiation, survival, and activation are mainly regulated by IL-5 [39,40]. However, it has been suggested that local differentiation, maturation, and activation of eosinophils in the airways may contribute to persistent sputum eosinophilia in prednisone-dependent patients who may have normal blood eosinophil counts.…”

“…This local event may be driven by IL-5 and IL-13, which are produced locally by relatively corticosteroid-insensitive ILC-2s [41]. Eosinophils leave the bloodstream and migrate to inflamed tissues because of the effect of surface receptors (IL-5Rα, CC-chemokine receptor 3, cysteinyl leukotriene type 1 receptor, and α4ß1 and α4ß7 integrins) and the influence of several cytokines and chemokines such as IL-4, IL-5, and IL-13 and CCL11, CCL24, and CCL26 (also known as eotaxins 1, 2, and 3, respectively) [39,40,42].…”

Eosinophil‐to‐monocyte ratio is an excellent predictor of acute cellular rejection in pancreas transplant alone recipients

“…According to recent studies, eosinophils can interact with various immune cells including T and B cells . Eosinophils act as not only terminal effector cells but also as modulators by amplifying the Th2 cell response in allergic inflammation .…”

“…32 According to recent studies, eosinophils can interact with various immune cells including T and B cells. 33 Eosinophils act as not only…”

Circulating miRNAs as diagnostic tool for discrimination of respiratory disease: Asthma, asthma‐chronic obstructive pulmonary disease (COPD) overlap and COPD

“…Additional supporting information may be found online in the Supporting Information section at the end of the article. DOI: 10.1111/all.13916 Circulating miRNAs as diagnostic tool for discrimination of respiratory disease: Asthma, asthma-chronic obstructive pulmonary disease (COPD) overlap and COPD To the Editor, Asthma is a respiratory condition characterized by reversible airflow obstruction and airway inflammation usually provoked by eosinophils, 1 which is usually associated with atopy and early onset.…”