Interleukin 17A Exacerbates Atherosclerosis by Promoting Fatty Acid-binding Protein 4-mediated ER Stress in Macrophages

Rationale: Apoptosis and fatty acid-binding protein-4 (FABP4) induced-endoplasmic reticulum (ER) stress in macrophage is an important pathological process in several vascular occlusive diseases, including atherosclerosis, both of which are accelerated by lipids or inflammatory cytokines.

Objective: To determine whether interleukin 17A (IL-17A) accelerates atherosclerosis through activating FABP4-mediated ER stress in macrophage.

Methods And Results: We show here that IL-17A induced ER stress in both murine and human-derived macrophages in vitro, and in the atherosclerotic lesions of ApoE-/- mice. Treating ApoE-/- mice with a chemical chaperone alleviated IL-17A-mediated ER stress and macrophage apoptosis, which was accompanied by recovered atherogenesis. Mechanistically, IL-17A up-regulated the expression of FABP4 (aP2), a cytosolic lipid chaperone that is able to promote lipid-induced macrophage ER stress, through NF-κB and ERK/p38 mitogen-activated protein kinase (MAPK) pathways in macrophages. The inhibition of aP2 expression with a specific chemical inhibitor significantly blocked IL-17A-accelerated ER stress and apoptosis in plaque, and partially rescued IL17A-induced atherogenesis.

Conclusions: The data collectively establish a previously unrecognized link between IL-17A and ER stress through cytosolic lipid chaperone aP2 in macrophages and provide a new insight for understanding the role of IL-17A in atherosclerosis.