Increased atherosclerosis in mice reconstituted with apolipoprotein E null macrophages

Area of Science:

• Cardiovascular Research
• Immunology
• Metabolic Diseases

Background:

• Macrophage-derived foam cells are key components of atherosclerotic lesions.
• Apolipoprotein E (apoE) is abundantly expressed by these foam cells.
• The specific role of macrophage-secreted apoE in atherogenesis requires further investigation.

Purpose of the Study:

• To elucidate the physiological role of apolipoprotein E (apoE) secretion by macrophages in the development of atherosclerosis.
• To determine if macrophage-derived apoE influences foam cell formation and lesion progression.

Main Methods:

• Utilized bone marrow transplantation to reconstitute C57BL/6 mice with either apoE-null or wild-type macrophages.
• Administered an atherogenic diet to the reconstituted mice for 13 weeks.
• Analyzed atherosclerosis development, serum cholesterol levels, and lipoprotein profiles.

Main Results:

• Mice reconstituted with apoE-null macrophages exhibited a 10-fold increase in atherosclerosis compared to controls.
• No significant differences in serum cholesterol or lipoprotein profiles were observed between groups.
• ApoE expression was notably absent in macrophage-derived foam cells of mice with apoE-null marrow.

Conclusions:

• Macrophage-derived apolipoprotein E plays a crucial protective role in early atherogenesis.
• The absence of apoE expression in macrophages promotes foam cell formation, a critical step in lesion development.
• Targeting macrophage apoE could be a potential therapeutic strategy for preventing atherosclerosis.