Investigating the function of thymic eosinophils
Date
2026
Authors
Gatti, Dominique
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Abstract
Eosinophils reside in the thymus of humans, mice and other vertebrates, yet their function during steady-state development remains poorly defined. However, two, non-mutually exclusive, functional roles have been proposed: that eosinophils contribute to T cell development and/or support thymic tissue maintenance and repair. In this thesis we examined both proposed functions of thymic eosinophils using mouse models.
We began with a broad characterization of thymic eosinophils at different time points throughout life and investigated the factors that affect their accumulation within the thymus. We then sought to understand their population dynamics and interrogated how eosinophils maintain residency in the thymus. Finally, using eosinophil-deficient mice, we investigated two possible roles that eosinophils might contribute to in the thymus. In young mice, we quantified thymocyte subsets to understand the influence of eosinophils on T cell development. In adult mice, we exploited pregnancy-induced thymic involution—a physiological model of acute thymic atrophy—to determine whether eosinophils facilitated thymic repair postpartum.
Collectively, this thesis provides insight into the complexities of thymic T cell development as the cell types and signals governing thymocyte maturation are still not fully understood. Identifying the mechanisms that shape T cell ontogeny has important implications for advancing fundamental principles of developmental immunology and for improving our understanding of immune-mediated disease. Moreover, defining the functional role of eosinophils in the thymus will help clarify the potential immunological consequences of eosinophil-targeted therapies. For example, infants born to birth parents that receive eosinophil-depleting treatments may experience transient eosinophil deficiency during early life—when immune development is highly sensitive to environmental and cellular cues. By investigating both the role of eosinophils in postpartum thymic regeneration in dams and their contribution to T cell ontogeny in pups, this thesis provides a more comprehensive understanding of how eosinophils may influence thymic biology and immune development.
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Keywords
Thymus, Eosinophils, Regulatory T cells, Early Life, Gastrointestinal Tract