Pituitary-Thyroid Axis and Immune System: A Reciprocal Neuroendocrine-lmmune Interaction

Abstract

A good body of experimental and clinical results has supported the existence of numerous reciprocal interactions among the nervous, endocrine and immune systems. Increasing evidence has been accumulated in the last years on the interaction between pituitary-thyroid hormones and the immune system on the basis of either the existence of receptors for thyreotropic and thyroid hormones on lymphocytes or the frequent immune alteration in physiological and pathological fluctuations of thyroid hormones. The data were obtained either in animals with experimentally induced hyper- or hypothyroidism or in humans with various hyperthyroid or hypothyroid situations. Conversely, immune-derived products such as lymphokines and monokines have been shown able to influence the pituitary-thyroid axis modulating either the thyroid hormone levels or the hormone/cytokine production by thyrocytes. The present paper aims at summarizing the data available on the existence of thyroid-immune interactions, and at analyzing the possible integration between pituitary-thyroid hormones and immune factors in favoring the development and maintenance of both thymic and peripheral immune efficiency. The relevance of pituitary-thyroid-immune interactions is discussed for its implication in the ageing process.

Integrative study of hypothalamus–pituitary–thyroid–immune system interaction: thyroid hormone-mediated modulation of lymphocyte activity through the protein kinase C signaling pathway

“…In accordance with our results, a decrease in the proliferative responses to either T cell (Con A and PHA) or B cell (pokeweed mitogen (PWM)) mitogens in splenic and peripheral blood lymphocytes from hypothyroid animals (Chatterjee & Chandel 1983, Fabris et al 1995 has been previously reported. Furthermore, T3 administration was found to restore lymphocyte blastogenic responses in thyroidectomized rats (Chatterjee & Chandel 1983).…”

“…Thus, either an enhancing or suppressing effect of primary antibody responses (Fabris et al 1995, Klecha et al 2000 or of T and B lymphocyte proliferation (Chatterjee & Chandel 1983, Klecha et al 2000 was demonstrated in hyperthyroid conditions. Opposing data could be reflecting differences among species or among the hormonal treatment established.…”

“…Thyroid hormones play critical roles in differentiation, growth and metabolism (Yen 2001). Although thyroid hormone participation in primary and secondary lymphopoiesis has been described (for review see Fabris et al (1995), in general their effects on the immune system have received comparatively less attention than those from hormones of the hypothalamus-pituitary-adrenal axis , Wang & Klein 2001. This fact could be related to the dominating role of autoimmunity in the pathogenesis of thyroid disorders .…”

“…Hypothyroidism in humans, or experimentally induced hypothyroidism (propylthiouracil (PTU) treatment) and thyroidectomy in rodents, has been shown to diminish thymic activity, effects that were reversed by treatment with thyroid hormones (Fabris et al 1995). In addition, hypothyroid experimental conditions lead to spleen and lymph node involution, as well as to depressed humoral and cell-mediated immune responses (Chatterjee & Chandel 1983, Ohashi & Itoh 1994, Klecha et al 2000.…”

Preliminary evidence of immune function modulation by thyroid hormones in healthy men and women aged 55–70 years

“…Evidence, predominantly from animal studies, also suggests a direct reciprocal relationship exists between the thyroid gland and the immune system (Fabris et al 1995, Klein 2006. Thyroid hormones are involved in numerous physiological processes, such as development, growth and the metabolism of lipids and carbohydrates.…”