In terms of the immune response in humans nutrients have a very important role to play and none more so than vitamin A. a lack of vitamin A results in altered intestinal immune homeostasis. This essential micronutrient supports adaptive immunity through its metabolite, retinoic acid (RA), which is highly enriched in the gastrointestinal tract.
This study shows that nutrient deficiency is not associated with a global immunosuppression, but instead can result in the specific activation of a distinct branch of barrier immunity. Furthermore, it emphasises the role of Intestinal Lymphoid Cells as important mediators of intestinal immune homeostasis.
The abundance of innate and adaptive immune cells that reside together with trillions of beneficial commensal microorganisms in the mammalian gastrointestinal tract requires barrier and regulatory mechanisms that conserve host-microbial interactions and tissue homeostasis. This homeostasis depends on the diverse functions of intestinal epithelial cells (IECs), which include the physical segregation of commensal bacteria and the integration of microbial signals. Hence, IECs are crucial mediators of intestinal homeostasis that enable the establishment of an immunological environment permissive to colonization by commensal bacteria.