The proatherosclerotic function of BCAT1 in atherosclerosis development of aged-apolipoprotein E-deficient mice

Atherosclerosis (AS) is an inflammatory vascular disease. Branched-chain amino acid transaminase 1 (BCAT1) has been implicated in inflammatory diseases, while its role in AS is unclear yet. In ApoE^-/- mice with a high fat diet (HDF), BCAT1 was highly up-regulated and more pronounced in aged than in young ApoE^-/- mice, which was abundantly expressed in macrophages located in AS lesions. The function of BCAT1 in AS was explored using lentivirus-mediated BCAT1 overexpression. ApoE^-/- mice fed a HFD with BCAT1 overexpression exhibited the worsening lipid deposition and pathological injury of aortic tissues, accompanied by aggravated hyperlipidemia as proved by increased serum triglyceride, total cholesterol, and low-density lipoprotein-cholesterol levels. Immunohistochemical staining of vascular cell adhesion molecule-1 (VCAM-1), monocyte chemoattractant protein-1 (MCP-1), and CD68 in the aortic root plaque suggested that BCAT1 overexpression could induce monocyte-endothelial cell adhesion and macrophages infiltration, thereby contributing inflammatory response by promoting TNF-α, IL-6, and IL-1β expression. Further, in vivo experiments, lipid accumulation, and inflammatory response induced by oxidized-LDL in RAW267.4 cells were also intensified or alleviated by BCAT1 overexpression or knockdown. Finally, BCAT1 overexpression aggravated AS development. These adverse effects of BCAT1 on hyperlipidemia, lipid accumulation, foaming cell formation, and inflammation suggested that the modulation of BCAT1 might be a potential approach to prevent AS disease.