Study summary · research use only
Neuroendocrine control of thymus physiology
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This review summarizes literature on how hormones and neuropeptides influence thymus physiology; species not specified. The authors describe the thymus as a lymphoid organ where T cell precursors differentiate before migrating to peripheral lymphoid organs, shaped by interactions with epithelial cells, macrophages, dendritic cells, fibroblasts, and extracellular matrix in the thymic microenvironment. According to the review, hormones and neuropeptides modulate expression of major histocompatibility complex products, extracellular matrix-mediated adhesion, cytokine production, and thymic endocrine function including thymulin production, with evidence of a bidirectional relationship between thymic peptides and hormone production. The review also describes hormone and neuropeptide involvement in thymic cell proliferation, programmed cell death, and T cell differentiation, concluding that neuroendocrine control of the thymus involves a complex network of intrathymic hormone and neuropeptide production and receptor expression.
Abstract
The thymus gland is a central lymphoid organ in which bone marrow-derived T cell precursors undergo differentiation, eventually leading to migration of positively selected thymocytes to the peripheral lymphoid organs. This differentiation occurs along with cell migration in the context of the thymic microenvironment, formed of epithelial cells, macrophages, dendritic cells, fibroblasts, and extracellular matrix components. Various interactions occurring between microenvironmental cells and differentiating thymocytes are under neuroendocrine control. In this review, we summarize data showing that thymus physiology is pleiotropically influenced by hormones and neuropeptides. These molecules modulate the expression of major histocompatibility complex gene products by microenvironmental cells and the extracellular matrix-mediated interactions, leading to enhanced thymocyte adhesion to thymic epithelial cells. Cytokine production and thymic endocrine function (herein exemplified by thymulin production) are also hormonally controlled, and, interestingly in this latter case, a bidirectional circuitry seems to exist since thymic-derived peptides also modulate hormonal production. In addition to their role in thymic cell proliferation and apoptosis, hormones and neuropeptides also modulate intrathymic T cell differentiation, influencing the generation of the T cell repertoire. Finally, neuroendocrine control of the thymus appears extremely complex, with possible influence of biological circuitry involving the intrathymic production of a variety of hormones and neuropeptides and the expression of their respective receptors by thymic cells.
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