Cyclooxygenase‐2 can be induced by inflammatory stimuli, such as Ang II.9 In endothelial cells, COX‐2 expression was significantly increased after exposure to Ang II.20, 21 Prostaglandin E2 (PGE2), synthesized by macrophages and SMCs, increases the production of matrix metalloproteinases (MMPs) and leads to the degradation of the vascular wall.22 Prior study has shown that macrophage and SMCs may be the major cells targeted by Tregs in the treatment of AAA.15 Therefore, macrophages and SMCs were treated with Ang II after Tregs in our experiment. Here, AGT is linked to triple-A syndrome.