The Role of IL-5 in Type 2 Inflammatory Diseases

Abstract

Type 2 inflammation is involved in severe asthma (SA), chronic rhinosinusitis with nasal polyps (CRSwNP), and eosinophilic granulomatosis with polyangiitis (EGPA). The pathogenesis of these diseases involves various immune system cells and target tissues, along with numerous cytokines, chemokines, and other inflammatory molecules. The role of eosinophils and the cytokine IL-5 and its receptor (IL-5R) is becoming a significant focus in these diseases, with numerous studies, from in vitro experiments to clinical trials, demonstrating correlations between IL-5 levels with eosinophil numbers and activity in SA, CRSwNP, and EGPA. Eosinophils and IL-5 are involved, both directly and indirectly, in disease initiation and exacerbation, as well as in tissue remodelling and disease progression. An advisory board of experts discussed how understanding the actions of IL-5 within Type 2 inflammation in SA, CRSwNP, and EGPA can highlight the importance of its role in managing patients with these diseases and help identify suitable biomarkers for disease onset, exacerbation, and progression. Therapies targeting eosinophil generation, priming, and activation could lead to more effective disease control and help prevent the tissue damage associated with these conditions, which can be difficult to reverse in chronic cases.