Enhanced Aortic Macrophage Lipid Accumulation and Inflammatory Response in LDL Receptor Null Mice Fed an Atherogenic Diet

The effect of an atherogenic diet on inflammatory response and elicited peritoneal macrophage (MI center dot) cholesterol accumulation in relation to aortic lesion formation was assessed in LDL receptor null (LDLr-/-) mice. Mice were fed an atherogenic or control diet for 32 weeks. The atherogenic relative to control diet resulted in significantly higher plasma monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) concentrations, more aortic wall MI center dot deposition, higher serum non HDL-cholesterol concentrations and total cholesterol to HDL-cholesterol ratios, and greater accumulation of both aortic free and esterified cholesterol. Elicited peritoneal MI center dot selectively accumulated longer chain unsaturated fatty acids in their membrane, independent of the dietary fatty acid profile. Elicited peritoneal MI center dot isolated from mice fed the atherogenic relative to control diet had significantly less arachidonic acid levels, accumulated significantly higher esterified cholesterol, had significantly higher mRNA levels and secretion of MCP-1, and mRNA and protein levels of ATP-binding cassette A1. Diet treatment had no significant effect in elicited peritoneal MI center dot on TNF alpha and IL-6 mRNA levels and secretion. These data suggest that the atherogenic relative to control diet resulted in higher plasma inflammatory factor concentrations, less favorable lipoprotein profile, higher elicited peritoneal MI center dot cholesterol accumulation and inflammatory factor secretion, and more aortic wall MI center dot deposition, which in turn were associated with greater aortic cholesterol accumulation.