Savino W, Dardenne M
Department of Immunology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
Endocr Rev. 2000 Aug;21(4):412-43. doi: 10.1210/edrv.21.4.0402.
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.
胸腺是一个中枢淋巴器官，骨髓来源的T细胞前体在此经历分化，最终导致阳性选择的胸腺细胞迁移至外周淋巴器官。这种分化伴随着细胞在胸腺微环境中的迁移而发生，胸腺微环境由上皮细胞、巨噬细胞、树突状细胞、成纤维细胞和细胞外基质成分组成。微环境细胞与正在分化的胸腺细胞之间发生的各种相互作用受神经内分泌控制。在本综述中，我们总结了相关数据，这些数据表明胸腺生理学受到激素和神经肽的多效性影响。这些分子通过微环境细胞和细胞外基质介导的相互作用调节主要组织相容性复合体基因产物的表达，导致胸腺细胞与胸腺上皮细胞的黏附增强。细胞因子的产生和胸腺内分泌功能（此处以胸腺素的产生为例）也受激素控制，有趣的是，在后一种情况下，似乎存在双向回路，因为胸腺衍生的肽也调节激素的产生。除了在胸腺细胞增殖和凋亡中的作用外，激素和神经肽还调节胸腺内T细胞的分化，影响T细胞库的产生。最后，胸腺的神经内分泌控制显得极其复杂，可能涉及胸腺内多种激素和神经肽的产生以及胸腺细胞对其各自受体的表达的生物回路的影响。
