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 & 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.).