Macrophage colony stimulating factor prevents the progression of atherosclerosis in Watanabe heritable hyperlipidemic rabbits

The early atherosclerotic lesion is characterized by the presence of macrophage-derived foam cells. Macrophage colony stimulating factor (M-CSF) specifically stimulates the functions of the monocytemacrophages. To elucidate the effects of M-CSF in the atherogenic process in vivo, we administered human recombinant M-CSF into Watanabe heritable hyperlipidemic (WHHL) rabbits, an animal model for familial hypercholesterolemia. Three hundred micrograms of M-CSF were intravenously injected into WHHL rabbits aged 2.5 months, three times a week for 8.5 months. After the M-CSF treatment, we found very retarded progression of atherosclerosis. The accumulation of cholesterol ester was remarkably decreased in the aortae of M-CSF-treated animals (0.60 ± 0.32 mg/g tissue), as compared to those of controls (4.32 ± 0.61 mg/g tissue). Furthermore, the percentage of the surface area of the aorta with macroscopic plaque in animals treated with M-CSF was 14.3 ± 6.2%, much less than that in controls receiving saline injection (38.8 ± 8.0%). Thus, M-CSF definitely prevented the progression of atherosclerosis in WHHL rabbits by influencing macrophage functions.