Ghrelin vaccination decreases plasma MCP-1 level in LDLR(-/-)-mice

Ghrelin is a novel peptide hormone having growth hormone releasing activity and many endocrine and metabolic functions. In rats and pigs, ghrelin immunizations have recently been shown to induce an antibody response against ghrelin simultaneously with a decrease in body weight gain. Our aim was to test the role of ghrelin immunization on atherosclerosis and weight gain in mice. LDLR(-/-)-mice (n=36) were immunized with ghrelin-PADRE, PADRE alone and PBS and then placed on a high fat diet for 22 weeks. Weight gain and food intake were followed throughout the study. Acylated and total ghrelin, cytokines and MCP-1 were analyzed from plasma using commercial kits. Stomach ghrelin was assessed using qRT-PCR and immunohistochemistry. Atherosclerosis was determined from aorta and cross-sections at the end of study. Mice immunized with ghrelin-PADRE developed high plasma IgG titers to ghrelin simultaneously with a significant increase in plasma acylated and total ghrelin levels. Plasma MCP-1 levels decreased in mice immunized with ghrelin-PADRE compared to mice immunized with PADRE and PBS. There were no differences in atherosclerosis determined from aorta and cross-sections as well as in body weights and food intake in LDLR(-/-)-mice between the different immunization groups. Our data indicates that ghrelin-PADRE vaccination induces a strong exclusive IgG response to ghrelin and increases plasma acylated and total ghrelin levels in mice. Ghrelin vaccination decreases plasma MCP-1 levels even though no effects on developing signs of atherosclerosis or weight gain in mice were observed.