Multiple facets of melatonin in immunity: Clinical applications

Abstract

Nowadays, the effector capacity of melatonin in the immune system is indisputable. The almost ubiquitous distribution of melatonin receptors, its immune synthesis, and the effects of several immunological mediators on the melatonin production reinforce the concept of the melatonin/immune bidirectional circuit. Throughout the present chapter, we have highlighted that melatonin acts on the immune response by combined mechanisms which mainly involve the modulation of cytokines and the oxidative stress markers production. Overall, melatonin acts as an immune activator in basal or immunodepressed conditions, whereas it might exert a negative regulation under transient or chronic exacerbated immune response. Due to the variety of the melatonin immunomodulatory actions, it has been tested in extensive models. Thus, the clinical relevance of the several faces of melatonin on immune conditions such as infection, autoimmunity, vaccination, and immunosenescence as well as transplant and cancer is also reviewed.