Role of Vitamin A in Modulating Graft-versus-Host Disease.

Vitamin A is an essential micronutrient that participates in a wide range of biological processes. Retinoic acid (RA) is an active metabolite of vitamin A that functions as an immune regulator. Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (HSCT). It is characterized by extensive inflammation arising from an alloimmune response involving various host and donor immune cells. Since vitamin A affects different immune cell lineages and regulates an array of immune responses, vitamin A, and more specifically retinoic acid, is likely to influence the incidence and/or severity of GVHD. Indeed, recent preclinical and clinical data support this concept. In this review, we briefly summarize recent advances in our understanding of the potential role of vitamin A in modulating GVHD risk after allogeneic HSCT.