Metformin Downregulated Adipose Differentiation Related Protein Expression To Postpone Atherosclerosis Development

As a chronic inflammatory disease, atherosclerosis occurs throughout the development and progression of cardiovascular and cerebrovascular diseases. Foam cell formation and accumulation are critical steps in the development of atherosclerosis. As the characteristics of foam cell, lipid droplets(LD) metabolism influences the formation of foam cell. The metabolism of LD is regulated by a variety of lipid droplet surface proteins. As one of the perilipin members, adipose differentiation related protein(ADRP) plays an critical role in the formation of foam cell and the pathogenesis of atherosclerosis. Besides a excellent hypoglycemic effect, metformin also has a cardiovascular protective effect that can inhibit the occurrence and development of atherosclerosis, heart failure, myocardial infarction. But the specific mechanism is unclear yet, possibly by improving insulin resistance, regulating lipid metabolism, reducing inflammation, protecting endothelial cells.In this study, we researched the function of metformin in atheromatous plaques and foam cells, and the expression of ADRP and histone demethylase JMJD3. Using Apo E knockout mice model of atherosclerosis, THP-1 macrophages derived foam cells, and primary peritoneal macrophages, we were going to determine the specific role of metformin in treatment of atherosclerosis and inhibition the intracellular lipid accumulation in the formation of foam cells, and to clarify the mechanism of regulating ADRP expression. The results of this study could clarify the protective effect and the possible mechanisms of metformin in atherosclerosis, which provided a basis for clinical application of metformin. 1. Metformin inhibited the formation of atheromatous plaque in Apo E knockout miceBy lavaging metformin in Apo E knockout mice, we found that metformin could reduce atheromatous plaque area, downregulate the m RNA and protein expression of ADRP and JMJD3 in plaques. In addition, metformin could decrease the body weight and fasting blood glucose of Apo E knockout mice fed with high fat diet(HFD), but no significant changes were found between triglycerides, total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterolt. Therefore, these results suggested that metformin could inhibit atheromatous plaque formation. 2. Metformin inhibited the formation of macrophage-derived foam cellsTo verify how metformin inhibited atheromatous plaque formation, we observed the morphology of LD, and determined the contents of lipids and protein expression levels in THP-1 and primary peritoneal macrophage derived foam cell model. We found that metformin could reduce the amounts of LD, lower triglyceride levels, and inhibit the accumulation of lipid in foam cells, which indicated that metformin could suppress LPS-induced foam cell formation. At the same time, metformin could downregulate the expression of ADRP and JMJD3 during the development of foam cells. Furthermore, we found that different concentrations of metformin had similar effects on the expression of ADRP and JMJD3. Therefore, We believed that metformin could inhibit the foam cell formation, and regulate the expression of ADRP and JMJD3. 3. Metformin supressed ADRP expression by downregulating JMJD3In order to verify the role of ADRP and JMJD3 in the mechanism of metformin inhibited the formation of atherosclerosis, we investigated the roles of ADRP, JMJD3 and their relationship in the development of foam cells using gene silencing and overexpression technique, as well as the separation of primary JMJD3-deficiency peritoneal macrophages. It was found that either silencing or overexpression of ADRP could weaken the inhibition of metformin on foam cell formation. However, neither overexpression nor silencing of ADRP could affect the expression of JMJD3. Furthermore, JMJD3 deficiency could inhibit the foam cell formation, and downregulate the expression of ADRP. Therefore, we believed that metformin could suppress ADRP expression to inhibit the development of atherosclerosis by downregulating JMJD3.In this study, Apo E knockout mice of atherosclerosis, THP-1 and primary peritoneal macrophage-derived foam cells were used, and the amounts of LD, lipid contents, protein levels during foam cell formation in atheromatous plaque had been analyzed. We concluded that metformin could supress ADRP expression by downrgulating JMJD3, thereby inhibited the lipid accumulation of foam cell formation, and then improved the forming of atheromatous plaque, eventually exhibited anti-atheromatous effects.