Sicyos angulatus ameliorates atherosclerosis through downregulation of aortic inflammatory responses in apolipoprotein E-deficient mice

Sicyos angulatus (SA), a summer annual vine originating from Northeastern USA, is a widely distributed noxious invasive plant. However, the clinical application of SA has not been investigated previously. The purpose of present study was to determine the effects of SA on atherosclerosis and its underlying mechanism. Atherosclerosis was induced by feeding apolipoprotein E-deficient (apoE-/-) mice with an atherogenic diet for 8 weeks. SA was administered daily by oral gavage during induction of atherosclerosis. ApoE-/- mice treated with SA demonstrated a significant reduction in atherosclerotic plaque area in the whole aorta and aortic sinus compared with vehicle-treated mice. The plasma lipid profiles, including triglyceride, total cholesterol, high-density lipoprotein and low-density lipoprotein, were not affected by SA administration. Of note, gene expression levels of proatherogenic cytokines including tumor necrosis factor α (Tnfα) and interleukin-6 (Il-6) were significantly decreased in the aorta of SA administered apoE-/- mice. In lipopolysaccharide-stimulated RAW 264.7 macrophage cells, SA also inhibited the induction Tnfa, Il-6 and Il-1β in a dose-dependent manner. Furthermore, gene expression levels of endothelial cell adhesion molecules, including vascular cell adhesion protein 1 and intercellular adhesion molecule 1 were reduced in the aorta of apoE-/- mice treated with SA, which was followed by diminished aortic infiltration of monocytes/macrophages. In conclusion, to the best of our knowledge, this is the first study to demonstrate that SA is able to suppress the development of atherosclerosis by inhibiting the aortic expression of proinflammatory factors in atherogenic diet-fed apoE-/- mice. The present study may provide novel insights into the application of the environmentally problematic weed SA as a therapeutically effective natural product for preventing atherosclerosis.