Extracellular matrix mediated neuroendocrine control of the thymus

The thymus is the primary lymphoid organ responsible for the generation of a self-tolerant and immunocompetent T-cell repertoire. Its function is not autonomous but is finely tuned by a complex neuroendocrine network, integrating signals from the central nervous system and the endocrine system to modulate thymopoiesis. While the roles of classical hormones and neurotransmitters in regulating thymic epithelial cell (TEC) function and T-cell development are increasingly recognized, the mechanistic pathways by which these signals are integrated within the thymic microenvironment still have much to be understood. A key, yet underexplored, component of the thymic microenvironment is the extracellular matrix (ECM). It is very clear today that ECM is not a passive scaffold but a dynamic structure that presents critical signals for thymocyte migration, proliferation, and selection. This review synthesizes current evidence to propose a novel paradigm: the thymic ECM acts as a key mediator of neuroendocrine control. We explore how specific ECM molecules, such as laminins, collagens, and fibronectin, expressed by TECs and other microenvironmental cells, can be modulated by neuroendocrine ligands. Furthermore, we discuss how these ECM modulations directly impact the presentation of key receptors, such as integrins, thereby influencing the critical crosstalk between a given thymic niche and developing lymphocytes. By delineating the ECM-mediated mechanisms, this review aims to provide a more holistic understanding of how neuroendocrine factors govern thymic physiology, with implications for aging, stress-related immunosenescence, and therapeutic strategies aimed at thymic regeneration.