Ghrelin receptor deficiency aggravates atherosclerotic plaque instability

Ghrelin has been found to be associated with anti-inflammatory effects, inhibition of atherosclerotic plaque formation, and plaque stability in the cardiovascular system. We investigated whether ghrelin affected atherosclerotic plaque and inflammation found in atherosclerosis. We crossed ghrelin receptor knock out mice (growth hormone secretagogue receptor (GHSR)-/-) and low-density lipoprotein receptor-null (low-density lipoprotein receptor (LDLR)-/-) mice. In this model, atherosclerotic lesions were promoted by administering a high-fat, high-cholesterol, Western-type diet for 18 weeks. Serum lipid levels, atherosclerotic plaque on the aortic arches, and expression of intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), T cells, macrophages, and smooth muscle cells of atherosclerotic plaque were observed. Although serum lipid levels and atherosclerotic plaque in aortic arches were not significantly different between GHSR+/+/LDLR-/- and GHSR -/-LDLR-/- mice, ICAM-1 and VCAM-1 protein expression in atherosclerotic plaques were increased in GHSR -/-LDLR-/- mice compared with GHSR+/+/LDLR-/- mice. T cells and macrophages were increased, while smooth muscle cells of atherosclerotic plaques were less in GHSR -/-LDLR-/- mice than that in GHSR+/+/LDLR-/- mice. In conclusion, ghrelin receptor deficiency aggravates atherosclerotic plaque instability and vascular inflammation but not the surface area of atherosclerotic plaque. This information will provide novel avenues for the treatment of patients with atherosclerosis.