Eosinophils (EOS): the Greek dawn goddess of the same name

Eosinophils (EOS), named after the Greek dawn goddess Eos, are multifunctional granulocytes with roles surpassing their well-established involvement in allergic diseases and parasitic infections. Herein, we highlighted the recent advancements in understanding the cellular structure, lineage development, surface receptors, and diverse phenotypes of EOS. In particular, we focused on their emerging roles in the tumor microenvironment and type 1 inflammatory responses. Additionally, we explored the cytokine signaling and transcription factor networks governing the differentiation of EOS, emphasizing the interplay among IL-5, IL-33, and GM-CSF. Notably, EOS exhibit phenotypic plasticity, with the ability to polarize into type 1 (E1) and type 2 (E2) subsets under different inflammatory conditions. This suggests their dual roles in antitumor and protumor activities. Our review underscores the potential of targeting EOS-specific receptors, including IL-5Rα and Siglec-8, for therapeutic interventions in EOS-related diseases. By combining recent findings on the metabolic milieu and interactions of EOS within complex tissue environments, we provide a comprehensive perspective on their physiological and pathological functions, paving the way for novel therapeutic strategies.