Survey of Opinion of Spanish Physicians on the Role of Eosinophils in Asthma and Other Diseases

摘要

Eosinophilic asthma is the most common inflammatory phenotype, accounting for over 25% of all patients with severe asthma. It is characterized by abnormal production of cytokines from type 2 helper T lymphocytes and type 2 innate lymphoid cells (ILC-2s), such as IL-4, IL-5, and IL-13, as well as a persistent increase and activation of eosinophils in blood and airways despite treatment with high-dose corticosteroids [1,2]. Blood and sputum eosinophilia are associated with more severe disease, poorer control, and worse prognosis [3]. The most direct way to diagnose severe eosinophilic asthma is through diagnosis of severe asthma, which is characterized by ≥2 exacerbations per year, dependence on oral corticosteroids to achieve asthma control, and a persistent increase in the eosinophil count in blood and the airways [2]. Eosinophils represent approximately 1% of peripheral blood leukocytes, and their differentiation, survival, and activation are regulated mainly by IL-5 [4]. Irrespective of the presence of allergy, severe, uncontrolled eosinophilic asthma is treated with biological drugs that target either eosinophils or the IL-5 pathway. On the one hand, biologic therapies targeting eosinophils include drugs blocking eosinophil recruitment, such as bertilimumab, which prevents accumulation of these cells in tissues [5]. On the other hand, drugs targeting the IL-5 pathway may be used, either directly against IL-5 (mepolizumab and reslizumab) or the IL-5 receptor (IL-5R a ) (benralizumab) [6-9]. By blocking the interaction between IL-5 and its receptor, the eosinophil count in blood and the airway decreases, as does survival of these cells, thus decreasing the symptoms of the disease. Another treatment approach includes inhibition of IL-4R a by blocking the action of IL-4 and IL-13. This strategy prevents the stimulation of type 2 inflammation, which contributes to asthma. Dupilumab is a monoclonal antibody targeting IL-R4 a? [10]. It was recently approved by the United States Food and Drug Administration for the treatment of moderate and severe asthma in patients with the eosinophilic phenotype.