Abstract 1117: Il-1 Signaling On Vascular Smooth Muscle Cells Accelerates Atherosclerosis After Murine Kawasaki Disease Vasculitis

Abstract

Objective: We have previously shown that Lactobacillus casei cell wall extract (LCWE)-induced Kawasaki disease (KD) vasculitis significantly accelerates atherosclerosis in hypercholesterolemic mice on high fat diet. IL-1 signaling is known to play a key role in both KD vasculitis and in the development of atherosclerosis. Here, we investigated the contribution of IL-1 signaling on vascular smooth muscle cells (VSMCs) in KD vasculitis-induced acceleration of atherosclerosis. Methods: Tamoxifen-inducible VSMC-specific IL-1 receptor ( Il1r1) knockout ( Myh11 Cre -ERT2 Il1r1 Δ/Δ ) mice and Il1r1 fl/fl littermate controls, all on ApoE -/- background, were injected with either PBS or LCWE. Following induction of KD vasculitis for 2 weeks, mice were fed a tamoxifen diet for 2 weeks to induce Il1r1 deletion on VSMCs, before being exposed to 8 weeks of Western diet to promote atherosclerosis. Results: KD vasculitis was associated with a significant acceleration of atherosclerosis, as expected. Myh11 Cre -ERT2 Il1r1 Δ/Δ mice had significantly diminished atherosclerotic plaque size, lipid composition, macrophage infiltration and necrotic core formation in aortic root as well as diminished lipid accumulation in aorta en face measurements compared with Il1r1 fl/fl control mice despite similar cholesterol levels. We also observed that Myh11 Cre -ERT2 Il1r1 Δ/Δ mice had significantly diminished endothelial adhesion molecules VCAM-1 and ICAM-1 expression in the lesion area and serum monocyte chemotaxis protein-1 (MCP-1) level compared with Il1r1 fl/fl control mice, consistent with the reduction of macrophage infiltration that we observed. Conclusions: Our results suggest an important pathophysiologic link between IL-1 signaling, specifically on VSMCs, and subsequent acceleration of atherosclerosis in hypercholesterolemic mice following KD vasculitis. Thus, further studies are warranted on the role of IL-1 signaling not only in acute KD, but also in the subsequent vascular remodeling and complications following acute KD vasculitis including atherosclerosis.