Minimally Oxidized Low-Density Lipoprotein Increases Expression of Scavenger Receptor A, CD36, and Macrosialin in Resident Mouse Peritoneal Macrophages

Abstract—Fully oxidized LDL (OxLDL) is believed to contribute to atherogenesis in part by virtue of uptake into macrophages via specific scavenger receptors. This phenomenon results in the formation of cholesterol-loaded foam cells, a major component of atherosclerotic lesions. The present study is directed at examining the effects of OxLDL and minimally oxidized LDL (MM-LDL) on scavenger receptor expression and activity in mouse peritoneal resident macrophages. Macrophages were preincubated with MM-LDL or OxLDL at concentrations of 25 or 50 μg/mL for 24 to 48 hours, after which their ability to bind and take up 125I-OxLDL or 125I-acetylated LDL (AcLDL) was determined. MM-LDL pretreatment induced a clear increase of cell association and degradation of 125I-OxLDL and 125I-AcLDL. Pretreatment with OxLDL also enhanced scavenger receptor activity, but to a lesser degree. Neither native LDL nor AcLDL had any effect. Scatchard analysis showed that preincubation with 50 μg/mL MM-LDL for 48 hours increased the Bm...