Enhancement of Atherosclerosis in Beta-2-Glycoprotein I-Immunized Apolipoprotein E-Deficient Mice

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Abstract
We have previously shown that low density lipoprotein receptor-deficient (LDL-RD) mice immunized with β2-glycoprotein I (β2GPI; a target of autoimmune anticardiolipin antibodies) developed enhanced early atherosclerosis, when fed a normal chow diet. The current study was undertaken to evaluate the effect of immunization with β2GPI and the addition of a high fat diet on the progression of atherosclerosis in the apolipoprotein E (ApoE)-deficient mouse. Six-week-old female ApoE-deficient mice (n = 10) were immunized subcutaneously with either human β2GPI or with ovalbumin, both emulsified in complete Freund’s adjuvant and fed a high fat diet for 6 weeks. The β2GPI-immunized mice were found to develop accelerated atherosclerosis when compared with their ovalbumin-immunized littermates (aortic lesion area of 137,500 ± 13,801 vs. 72,444 ± 14,465 µm2, respectively; p = 0.0067). The β2GPI-immunized mice developed high titers of anti-β2GPI antibodies, 10 days after the procedure, which were sustained until the sacrifice. LDL extracted from both study groups displayed similar susceptibility to ex vivo oxidation. These results confirm our previous study in which we found increased atherosclerosis in β2GPI-immunized LDL-RD mice fed a chow diet. In the current study we show that the proatherogenic effect of β2GPI immunization is maintained despite high cholesterol levels and is not associated with increased susceptibility of LDL to ex vivo oxidation.