Temporal and spatial determinants of eosinophil specialization across tissues

Eosinophils are multifunctional granulocytes involved in immune regulation, metabolism, and tissue repair. However, the extent of their heterogeneity across tissues and the underlying regulatory mechanisms remain poorly understood. Here, we present a comprehensive single-cell transcriptomic and proteomic atlas of murine eosinophils across diverse tissues. By integrating transcriptional profiling, high-dimensional surface proteomics, and in vivo fate mapping, we demonstrate that eosinophil identity is shaped by both tissue-specific cues and the duration of local residency. Long-lived eosinophils in the small intestine exhibit progressive transcriptional and spatial diversification, while short- and intermediate-lived populations in the lung and colon remain relatively uniform. We define a set of surface markers that delineate eosinophil maturation from bone marrow progenitors to long-term tissue-resident subsets. Leveraging this atlas, we identify the GM-CSF receptor α chain (Csf2ra) as a niche-restricted regulator selectively required for eosinophil maintenance in the colon. Together, these findings establish a framework in which time and tissue microenvironment jointly dictate eosinophil maturation, specialization, and function.