The role of heme oxygenase-1 in T cell-mediated immunity: The all encompassing enzyme

Heme oxygenase-1 (HO-1) is the rate-limiting enzyme of ferroheme metabolic pathway, which has the functions of antioxidation, anti-inflammatory, anti-apoptosis and anti-smooth muscle hyperplasia. Furthermore, HO-1 exerts a protective action in the diseases mediated by effector T lymphocytes such as T helper (Th)1, Th2 and Th17. In addition, regulatory T cells (Treg) control the activity of CD4(+)CD25(-) effector cells in a suppressive manner. Numerous studies indicate that the protective action of HO-1 in diseases is through CD4(+)CD25(+) Treg. This paper will review the current research and understanding of HO-1's role in T cells-mediated immunoregulation.