Thymic Endocrinology

Abstract

The thymus involutes relatively early in life; cellular immune deficiencies of aging correspond to decline in function of the hypothalamic-pituitary-endocrine axis. Recent studies point to important roles for the pituitary, the pineal, and the autonomic nervous system as well as the thyroid, gonads and adrenals in the thymus integrity and function. Thymic function at the local level requires complex cellular interactions among thymic stromal cells and developing thymocytes involving paracrine and autocrine mediators including interleukins (ILs) 1, 2, 6, 7, 8, colony-stimulating factors (CSFs), interferon-gamma, thymosin alpha 1, and zinc-thymulin. An important endocrine function of the thymus is to package zinc in zinc-thymulin for delivery to the periphery. Thymic involution has been treated with interleukins, thymic hormones, growth hormone, prolactin, melatonin, zinc, and others. Our work to reverse thymic involution in hydrocortisone-treated, aged mice with interleukins, thymosin alpha 1, and zinc will be reviewed. Recent efforts to treat successfully immune deficiency in aged and cancer-bearing humans will be presented.

Adhesion of Immature and Mature T Cells Induces inHuman Thymic Epithelial Cells (TEC) Activation of IL‐6Gene Trascription Factors (NF‐κB And NF‐IL6) and IL‐6Gene Expression: Role of αtβ1 and α6β4 Integrins

“…The molecular interactions between thymocytes and the subcapsular, cortical or medullary TEC are far from being elucidated because the pathways of human TEC differentiation are still uncertain and the TEC progenitors remain unidentifyed. However, key elements that might be involved ifi all these interactions are the cytokines, growth factors and neuropeptides differentially secreted by the two cell lineages Savino et al, 1998, Hadden J.W., 1998 Lee et al, 1994, Salomon et al, 1997.…”

Radiation-Induced Change in Lymphocyte Proliferation and its Neuroendocrine Regulation: Dose-Response Relationship and Pathophysiological Implications

“…Under physiological conditions, the HPA axis exerts a (tonic) repression on the immune system, preventing its overaction, especially on the growth and function of the thymus (Hadden, 1998;Sheridan et al, 1998). Hyperfunction of the HPA axis would lead to atrophy of the thymus and correspondingly suppression of immune functions.…”

Neurotensin-Containing Endocrine Cells and Neurotensin Receptor mRNA-Expressing Epithelial Cells in the Chicken Thymus.

“…It is well known that the neuroendocrine organs and thymus are involved in a bidirectional interaction: the epithelial cells in the thymus receive hormones released from extrathymic endocrine glands and produce thymic hormones which stimulate the proliferation and differentiation of T cells and the pituitary and hypothalamus (MORLEY et al, 1987;WEIGENT and BLALOCK, 1987;KENDALL, 1991;HADDEN, 1992). Recently, in addition to thymic hormones, the epithelial cells have been shown to produce pituitary hormones and hypothalamic hormones.…”