Interleukin-5 (IL-5) is central to eosinophil differentiation, survival, and activation. Subsequent studies confirmed IL-5 receptor expression and mapped downstream signaling, showing that IL-5 promotes not only survival but also trafficking and effector functions, including adhesion, degranulation, reactive oxygen species generation, mediator release (cytokines and cysteinyl leukotrienes), and extracellular trap formation.
However, the roles of eosinophils vary across diseases and tissue compartments. Multi-omics analyses of blood and tissue eosinophils across transcriptomic, proteomic, and lipid-metabolic layers reveal disease- and site-specific molecular states.
These data support two opposing classes of modulators that shape IL-5–driven programs: pro-inflammatory signals (IL-4/IL-13, IL-33, NOD2-mediated innate signaling, and IFN-γ) that drive inflammatory eosinophil changes and can cooperate in some settings, and counter-regulatory signals (IFN-α and all-trans retinoic acid [ATRA]) that restrain these changes. Such modulation may influence tissue retention, effector functions, and broader eosinophil activities, including antiviral and homeostatic roles.