An olive oil-rich diet reduces scavenger receptor mRNA in murine macrophages

During atherogenesis, a pathological accumulation of lipids occurs within a ortic intimal macrophages through uptake of oxidised LDL via scavenger rece ptors. Here we investigated whether some of the anti-atherosclerotic effect s ascribed to an olive oil rich-diet are mediated through effects on macrop hage scavenger receptors (MSR). Male C57 B16 mice aged 6 weeks were fed for 12 weeks on a low-fat diet (containing 25 g corn oil/kg) or on high-fat di ets containing 200 g coconut oil, olive oil or safflower oil/kg. Thioglycol late-elicited peritoneal macrophages were analysed for fatty acid compositi on by GC and the levels of mRNA coding for three MSR (MSRA type I, MSRA typ e II and CD36) were measured by reverse-transcription polymerase chain reac tion. Feeding mice diets enriched with different fats resulted in significa nt differences in the fatty acid profile of macrophages, which reflected th e fatty acid compositions of the diets. These differences were accompanied by a lower level of mRNA for MSRA type I, MSRA type II and CD36 in macropha ges from mice fed an olive-oil-enriched diet compared with the mice fed on the low-fat diet. These data suggest that part of the protective effect of olive oil against atherosclerosis might be via reducing macrophage uptake o f oxidised LDL. Whether this effect is due to the downregulation of gene tr anscription directly by unsaturated fatty acids or is the result of the eff ect of monounsaturated fatty acids or other components of olive oil on LDL composition and oxidation remains to be ascertained.