Immunomodulation by Melatonin: Its Significance for Seasonally Occurring Diseases

Abstract

Melatonin is not only synthesized by the pineal gland but also in many other organs and tissues of the body, particularly by lymphoid organs such as the bone marrow, thymus and lymphocytes. Melatonin participates in various functions of the body, among which its immunomodulatory role has assumed considerable significance in recent years. Melatonin has been shown to be involved in the regulation of both cellular and humoral immunity. Melatonin not only stimulates the production of natural killer cells, monocytes and leukocytes, but also alters the balance of T helper (Th)-1 and Th-2 cells mainly towards Th-1 responses and increases the production of relevant cytokines such as interleukin (IL)-2, IL-6, IL-12 and interferon-γ. The regulatory function of melatonin on immune mechanisms is seasonally dependent. This fact may in part account for the cyclic pattern of symptom expression shown by certain infectious diseases, which become more pronounced at particular times of the year. Moreover, melatonin-induced seasonal changes in immune function have also been implicated in the pathogenesis of seasonal affective disorder and rheumatoid arthritis. The clinical significance of the seasonally changing immunomodulatory role of melatonin is discussed in this review.

The Immunoendocrine Thymus as a Pacemaker of Lifespan

“…In the thymic cells, extrapineal melatonin can be found (synthesized) as well as melatonin synthesizing enzymes [57][58][59]. Both the thymic epithelial cells and thymocytes have MT1 and MT2 melatonin receptors [60].…”

Impact of melatonin on immunity: a review

“…Melatonin can modulate the balance between the immunity responses and tissue healing. Spontaneous alteration in melatonin level is probably responsible for seasonally occurring diseases such as rheumatoid arthritis [71]. According to that evidence, application of melatonin would be suitable for relief from those diseases and can be designated as a drug for supportive care [72].…”

Melatonina sintetizada por microglias de cerebelo em cultura regula o processo de fagocitose

“…Esta enzima pertence ao grupo de redutases que participa da proteção contra o estresse oxidativo (Pandi-Perumal et al, 2008).…”

“…No entanto, ao longo das últimas décadas, o papel regulatório da melatonina sobre as funções de defesa tem sido demonstrado por muitos grupos (Nelson e Demas, 1997;Gilad et al, 1998;Maestroni, 1998;Reiter et al, 2000;Carrillo-Vico et al, 2004;Pontes et al, 2006;Srinivasan et al, 2008).…”