TRAIL (TNF-related apoptosis-inducing ligand) belongs to the tumor necrosis factor (TNF) superfamily and is associated with initiating apoptosis. TRAIL has four major receptors: two death receptors DR4 and DR5, and two decoy receptors DcR1 and DcR2. TRAIL binds to the death receptors, which recruits the Fas-associated death domain (FADD) and activates caspases 8 and 10, which eventually leads to apoptosis (Pitti et al.; Wiley et al.; Zauli and Secchiero). It has been shown that mice lacking the expression of TRAIL have defects in thymocyte apoptosis and negative selection, and these mice had increased susceptibility to autoimmune diseases (Lamhamedi-Cherradi et al.).