Circulating adhesion molecules in apoE-deficient mouse strains with different atherosclerosis susceptibility

Recruitment of inflammatory cells in the arterial wall by vascular adhesion molecules plays a key role in development of atherosclerosis. Apolipoprotein E-deficient (apoE−/−) mice have spontaneous hyperlipidemia and develop all phases of atherosclerotic lesions. We sought to examine plasma levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) and sP-selectin in two apoE−/− strains C57BL/6 (B6) and BALB/c with early or advanced lesions. Mice were fed chow or a Western diet containing 42% fat, 0.15% cholesterol, and 19.5% casein. On either diet, BALB/c.apoE−/− mice developed much smaller atherosclerotic lesions and displayed significantly lower levels of sVCAM-1 and sP-selectin than B6.apoE−/− mice. The Western diet significantly elevated sVCAM-1 levels in both strains and sP-selectin levels in B6.apoE−/− mice. BALB/c.apoE−/− mice exhibited 2-fold higher HDL cholesterol levels on the chow diet and 15-fold higher HDL levels on the Western diet than B6.apoE−/− mice, although the two strains had comparable levels of total cholesterol and triglyceride. Thus, increased atherosclerosis is accompanied by increases in circulating VCAM-1 and P-selectin levels in the two apoE−/− mouse strains, and the high HDL level may protect against atherosclerosis by inhibiting the expression of adhesion molecules in BALB/c.apoE−/− mice.