Enhanced Atherosclerosis in TIPE2-Deficient Mice Is Associated with Increased Macrophage Responses to Oxidized Low-Density Lipoprotein

Atherosclerosis has been widely recognized as an inflammatory disease of the arterial wall in which macrophages play a major role. Yet, how macrophage-mediated pathology is regulated during atherosclerosis is poorly understood. TNF-α-induced protein 8-like 2 (TIPE2, also known as TNFAIP8L2) is highly expressed in resting macrophages and can negatively regulate inflammation through inhibiting immune receptor signaling. We report in this article that TIPE2 plays a crucial atheroprotective role likely by regulating macrophage responses to oxidized low-density lipoprotein (ox-LDL). TIPE2-deficient macrophages treated with ox-LDL produced more oxidative stress and proinflammatory cytokines, and exhibited heightened activation of the JNK, NF-κB, and p38 signaling pathways. As a consequence, TIPE2 deficiency in bone marrow-derived cells exacerbated atherosclerosis development in Ldlr(-/-) mice fed a high-fat diet. Importantly, ox-LDL markedly downregulated TIPE2 mRNA and protein levels in macrophages, suggesting that ox-LDL mediates atherosclerosis by TIPE2 inhibition. These results indicate that TIPE2 is a new inhibitor of atherosclerosis and a potential drug target for treating the disease.