Relative contributions of apolipoprotein(a) and apolipoprotein-B to the development of fatty lesions in the proximal aorta of mice

Transgenic mice expressing transgenes for both human apolipoprotein B-100 (h-apoB) and apolipoprotein(a) [apo(a)] were fed a high-fat, atherogenic diet for 14 weeks to examine the effect of lipoprotein(a) [Lp(a)] on the development of aortic rally lesions. The extent of lesions in the proximal region of the aorta of Lp(a) mice was measured by use of a computer-assisted image analysis of 20 sections per animal and compared with that of nontransgenic mice as well as mice expressing either the apo(a) or h-apoB transgene. The control (n=23) and apo(a) (n=22) transgenic mice had very small mean lesion areas (607 versus 128 μm² per section). The h-apoB- expressing mice (n=20) had significantly higher mean lesion areas (3288 μm² per section) than either the control or apo(a) transgenic animals. Coexpression of apo(a) and h-apoB transgenes resulted in only a modest increase in lesion area (4678 μm² per section, n=19). Thus, the expression of human apo(a) in C57BL/6/SJL hybrid mice fed an atherogenic diet failed to significantly potentiate the development of aortic fatty lesions in the absence or presence of high levels of h-apoB.