The neuroendocrine hormone leptin is known to have many roles, including regulating insulin sensitivity and reproductive function, but is most extensively characterized for its critical function as a satiety hormone. Interestingly, mice with naturally occurring mutations in leptin or membrane-bound leptin receptor suggest a role for leptin in immune function as they exhibit chronic thymic atrophy and suppressed immune responses.

New insights into the role of leptin in immunity are now emerging, and generally define leptin in the immune system as promoting phagocytosis, development of T helper 1 cells and general inflammation. Leptin has also been shown to play a role in autoimmune disorders by enhancing autoimmune dysregulation. Little is known, however, about specific roles for leptin signalling in the thymus on the underlying mechanisms driving thymic involution or thymic recovery after acute stress.

Gruver et al. report in this study carried out at the Duke University Medical Center, NC, USA, that leptin receptor is restricted to the medullary epithelial cells in the thymus. Using a model of endotoxemia-induced acute thymic involution and recovery, they demonstrate a role for supraphysiologic leptin in protection of thymic epithelial cells. Their studies support an intrathymic role for the metabolic hormone leptin in maintaining healthy thymic epithelium and promoting thymopoiesis, which is revealed when thymus homeostasis is perturbed by endotoxemia. Journal of Endocrinology, DOI: 10.1677/JOE-09-0179