Role of Interleukin 17 in Inflammation, Atherosclerosis, and Vascular Function in Apolipoprotein E–Deficient Mice

Abstract

Objective—: Interleukin 17A (IL17A) is involved in many inflammatory processes, but its role in atherosclerosis remains controversial. We examined the role of IL17A in mouse and human atherosclerosis. Methods and Results—: Atherosclerosis was induced in apolipoprotein E (ApoE) −/− and IL17A/ApoE −/− mice using high-fat feeding, angiotensin II infusion, or partial carotid ligation. In ApoE −/− mice, 3 months of high-fat diet induced interferon-γ production by splenic lymphocytes, and this was abrogated in IL17A/ApoE −/− mice. IL17A/ApoE −/− mice had reduced aortic superoxide production, increased aortic nitric oxide levels, decreased aortic leukocyte and dendritic cell infiltration, and reduced weight gain after a high-fat diet compared with ApoE −/− mice. Despite these favorable effects, IL17A deficiency did not affect aortic plaque burden after a high-fat diet or angiotensin II infusion. In a partial carotid ligation model, IL17A deficiency did not affect percentage of stenosis but reduced outward remodeling. In this model, neutralization of the related isoform, IL17F, in IL17A/ApoE −/− mice did not alter atherosclerosis. Finally, there was no correlation between IL17A levels and carotid intima-media thickness in humans. Conclusion—: IL17 contributes to vascular and systemic inflammation in experimental atherosclerosis but does not alter plaque burden. The changes in plaque composition caused by IL17 might modulate plaque stability.