Vitamins are essential nutrients which have to be taken up from exogenous sources. Vitamins exert multiple effects on the immune system due to their varied molecular actions. Some vitamins and derivatives have anti-oxidant activity and regulate redox-dependent stress responses, while others act as co-factors for enzymes and thereby can act as epigenetic modifiers. In this way vitamins like vitamin C and D thus modulate T-cell differentiation in vitro and in vivo. Deficiency of certain vitamins is associated with clinical symptoms, e.g. scurfy (vitamin C) and multiple sclerosis (vitamin D). Vitamin A derivatives like retinoic acid play a role for intestinal homeostasis and thus are relevant for chronic inflammatory bowel diseases like Morbus Crohn and Colitis ulcerosa. These few examples illustrate the importance to broaden our understanding of the fundamental roles of vitamins for immune regulation under physiologic and pathophysiological conditions.

Knowledge of the molecular mechanisms of vitamins is steadily increasing. As an example, vitamin C has been shown to act as cofactor for enzymes regulating DNA demethylation of e.g FoxP3, thereby increasing Treg activity and stability. Vitamin C also directly kills some colorectal carcinoma cells but not others. Vitamin D on the other hand drives T-cell differentiation towards Th2 pathway and thus IL-10 induction, to name but a few recent discoveries. At the translational level, high dose vitamin C is discussed to enhance cancer immunotherapies, as is vitamin D to ameliorate inflammation in multiple sclerosis. Despite these and other recent achievements, more research is needed to fully understand the molecular mechanisms of action of vitamins and to extrapolate clinical implications and therapeutic perspectives.

We welcome the submission of Original Research, Review, Mini Review, and Perspective articles on themes including, but not limited to:

· Modulation of innate immune responses by vitamins

· Epigenetic regulation by vitamins

· Regulation of T-cell specification and Treg development by vitamins

· Vitamins in intestinal homeostasis and dysregulation in inflammatory bowel diseases

· Microbe metabolism regulated by vitamins

· Translational perspectives for vitamins in inflammation, autoimmunity and cancer

We acknowledge the initiation and support of this Research Topic by the International Union of Immunological Societies (IUIS). We hereby state publicly that the IUIS has had no editorial input in articles included in this Research Topic, thus ensuring that all aspects of this Research Topic are evaluated objectively, and unbiased by any specific policy or opinion of the IUIS.

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Immunomodulation by Vitamins: Mechanistic insights and clinical translation